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-rw-r--r--compiler/rustc_abi/Cargo.toml6
-rw-r--r--compiler/rustc_abi/src/extern_abi.rs3
-rw-r--r--compiler/rustc_ast/Cargo.toml8
-rw-r--r--compiler/rustc_ast/src/ast.rs4
-rw-r--r--compiler/rustc_ast/src/token.rs22
-rw-r--r--compiler/rustc_ast/src/tokenstream.rs6
-rw-r--r--compiler/rustc_ast_lowering/Cargo.toml4
-rw-r--r--compiler/rustc_ast_lowering/src/block.rs3
-rw-r--r--compiler/rustc_ast_lowering/src/expr.rs17
-rw-r--r--compiler/rustc_ast_lowering/src/item.rs39
-rw-r--r--compiler/rustc_ast_lowering/src/lib.rs10
-rw-r--r--compiler/rustc_ast_lowering/src/pat.rs4
-rw-r--r--compiler/rustc_ast_passes/Cargo.toml5
-rw-r--r--compiler/rustc_ast_passes/messages.ftl17
-rw-r--r--compiler/rustc_ast_passes/src/ast_validation.rs55
-rw-r--r--compiler/rustc_ast_passes/src/errors.rs29
-rw-r--r--compiler/rustc_ast_passes/src/feature_gate.rs2
-rw-r--r--compiler/rustc_ast_pretty/Cargo.toml4
-rw-r--r--compiler/rustc_ast_pretty/src/pprust/state.rs17
-rw-r--r--compiler/rustc_attr_parsing/Cargo.toml4
-rw-r--r--compiler/rustc_attr_parsing/messages.ftl85
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/allow_unstable.rs26
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/body.rs7
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/cfg.rs2
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/codegen_attrs.rs299
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/confusables.rs14
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/crate_level.rs36
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/deprecation.rs46
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/dummy.rs2
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/inline.rs30
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/link_attrs.rs530
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/lint_helpers.rs28
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/loop_match.rs8
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/macro_attrs.rs29
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/mod.rs46
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/must_use.rs30
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/no_implicit_prelude.rs8
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/non_exhaustive.rs12
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/path.rs10
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/prelude.rs20
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/proc_macro_attrs.rs18
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/prototype.rs141
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/repr.rs23
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/rustc_internal.rs12
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/semantics.rs7
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/stability.rs49
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/test_attrs.rs21
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/traits.rs33
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/transparency.rs10
-rw-r--r--compiler/rustc_attr_parsing/src/attributes/util.rs39
-rw-r--r--compiler/rustc_attr_parsing/src/context.rs430
-rw-r--r--compiler/rustc_attr_parsing/src/interface.rs363
-rw-r--r--compiler/rustc_attr_parsing/src/lib.rs24
-rw-r--r--compiler/rustc_attr_parsing/src/lints.rs50
-rw-r--r--compiler/rustc_attr_parsing/src/parser.rs483
-rw-r--r--compiler/rustc_attr_parsing/src/session_diagnostics.rs241
-rw-r--r--compiler/rustc_attr_parsing/src/target_checking.rs269
-rw-r--r--compiler/rustc_attr_parsing/src/validate_attr.rs (renamed from compiler/rustc_parse/src/validate_attr.rs)22
-rw-r--r--compiler/rustc_baked_icu_data/Cargo.toml9
-rw-r--r--compiler/rustc_baked_icu_data/src/data/any.rs2
-rw-r--r--compiler/rustc_baked_icu_data/src/data/list_and_v1.rs.data71
-rw-r--r--compiler/rustc_baked_icu_data/src/data/macros.rs46
-rw-r--r--compiler/rustc_baked_icu_data/src/data/macros/fallback_likelysubtags_v1.data.rs40
-rw-r--r--compiler/rustc_baked_icu_data/src/data/macros/fallback_parents_v1.data.rs28
-rw-r--r--compiler/rustc_baked_icu_data/src/data/macros/fallback_supplement_co_v1.data.rs32
-rw-r--r--compiler/rustc_baked_icu_data/src/data/macros/list_and_v1.data.rs35
-rw-r--r--compiler/rustc_baked_icu_data/src/data/mod.rs57
-rw-r--r--compiler/rustc_baked_icu_data/src/lib.rs39
-rw-r--r--compiler/rustc_borrowck/Cargo.toml4
-rw-r--r--compiler/rustc_borrowck/messages.ftl2
-rw-r--r--compiler/rustc_borrowck/src/dataflow.rs44
-rw-r--r--compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs2
-rw-r--r--compiler/rustc_borrowck/src/diagnostics/mod.rs61
-rw-r--r--compiler/rustc_borrowck/src/diagnostics/move_errors.rs2
-rw-r--r--compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs776
-rw-r--r--compiler/rustc_borrowck/src/diagnostics/opaque_types.rs61
-rw-r--r--compiler/rustc_borrowck/src/diagnostics/region_errors.rs86
-rw-r--r--compiler/rustc_borrowck/src/handle_placeholders.rs220
-rw-r--r--compiler/rustc_borrowck/src/lib.rs33
-rw-r--r--compiler/rustc_borrowck/src/member_constraints.rs226
-rw-r--r--compiler/rustc_borrowck/src/region_infer/graphviz.rs10
-rw-r--r--compiler/rustc_borrowck/src/region_infer/mod.rs518
-rw-r--r--compiler/rustc_borrowck/src/region_infer/opaque_types.rs299
-rw-r--r--compiler/rustc_borrowck/src/region_infer/opaque_types/member_constraints.rs194
-rw-r--r--compiler/rustc_borrowck/src/region_infer/opaque_types/mod.rs697
-rw-r--r--compiler/rustc_borrowck/src/region_infer/opaque_types/region_ctxt.rs114
-rw-r--r--compiler/rustc_borrowck/src/region_infer/reverse_sccs.rs10
-rw-r--r--compiler/rustc_borrowck/src/root_cx.rs15
-rw-r--r--compiler/rustc_borrowck/src/type_check/canonical.rs105
-rw-r--r--compiler/rustc_borrowck/src/type_check/constraint_conversion.rs20
-rw-r--r--compiler/rustc_borrowck/src/type_check/free_region_relations.rs32
-rw-r--r--compiler/rustc_borrowck/src/type_check/liveness/trace.rs2
-rw-r--r--compiler/rustc_borrowck/src/type_check/mod.rs194
-rw-r--r--compiler/rustc_borrowck/src/type_check/opaque_types.rs333
-rw-r--r--compiler/rustc_borrowck/src/type_check/relate_tys.rs9
-rw-r--r--compiler/rustc_builtin_macros/Cargo.toml4
-rw-r--r--compiler/rustc_builtin_macros/messages.ftl11
-rw-r--r--compiler/rustc_builtin_macros/src/assert.rs35
-rw-r--r--compiler/rustc_builtin_macros/src/autodiff.rs435
-rw-r--r--compiler/rustc_builtin_macros/src/cfg_accessible.rs2
-rw-r--r--compiler/rustc_builtin_macros/src/derive.rs2
-rw-r--r--compiler/rustc_builtin_macros/src/deriving/from.rs133
-rw-r--r--compiler/rustc_builtin_macros/src/deriving/generic/ty.rs11
-rw-r--r--compiler/rustc_builtin_macros/src/deriving/mod.rs1
-rw-r--r--compiler/rustc_builtin_macros/src/errors.rs26
-rw-r--r--compiler/rustc_builtin_macros/src/format.rs8
-rw-r--r--compiler/rustc_builtin_macros/src/format_foreign.rs2
-rw-r--r--compiler/rustc_builtin_macros/src/lib.rs2
-rw-r--r--compiler/rustc_builtin_macros/src/proc_macro_harness.rs7
-rw-r--r--compiler/rustc_builtin_macros/src/test_harness.rs2
-rw-r--r--compiler/rustc_builtin_macros/src/util.rs3
-rw-r--r--compiler/rustc_codegen_cranelift/src/constant.rs8
-rw-r--r--compiler/rustc_codegen_cranelift/src/driver/aot.rs5
-rw-r--r--compiler/rustc_codegen_cranelift/src/linkage.rs3
-rw-r--r--compiler/rustc_codegen_gcc/.github/workflows/m68k.yml42
-rw-r--r--compiler/rustc_codegen_gcc/Cargo.lock8
-rw-r--r--compiler/rustc_codegen_gcc/Cargo.toml2
-rw-r--r--compiler/rustc_codegen_gcc/build_system/src/fmt.rs30
-rw-r--r--compiler/rustc_codegen_gcc/build_system/src/test.rs2
-rw-r--r--compiler/rustc_codegen_gcc/libgccjit.version2
-rw-r--r--compiler/rustc_codegen_gcc/rust-toolchain2
-rw-r--r--compiler/rustc_codegen_gcc/src/back/lto.rs33
-rw-r--r--compiler/rustc_codegen_gcc/src/back/write.rs7
-rw-r--r--compiler/rustc_codegen_gcc/src/base.rs2
-rw-r--r--compiler/rustc_codegen_gcc/src/consts.rs2
-rw-r--r--compiler/rustc_codegen_gcc/src/intrinsic/simd.rs1
-rw-r--r--compiler/rustc_codegen_gcc/src/lib.rs18
-rw-r--r--compiler/rustc_codegen_gcc/src/mono_item.rs3
-rw-r--r--compiler/rustc_codegen_gcc/tests/failing-run-make-tests.txt3
-rw-r--r--compiler/rustc_codegen_gcc/tests/failing-ui-tests.txt4
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/int.rs10
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/int_overflow.rs2
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/structs.rs8
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/volatile.rs8
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/volatile2.rs12
-rw-r--r--compiler/rustc_codegen_llvm/Cargo.toml6
-rw-r--r--compiler/rustc_codegen_llvm/src/abi.rs23
-rw-r--r--compiler/rustc_codegen_llvm/src/allocator.rs23
-rw-r--r--compiler/rustc_codegen_llvm/src/asm.rs11
-rw-r--r--compiler/rustc_codegen_llvm/src/attributes.rs28
-rw-r--r--compiler/rustc_codegen_llvm/src/back/archive.rs183
-rw-r--r--compiler/rustc_codegen_llvm/src/back/lto.rs90
-rw-r--r--compiler/rustc_codegen_llvm/src/back/mod.rs5
-rw-r--r--compiler/rustc_codegen_llvm/src/back/owned_target_machine.rs15
-rw-r--r--compiler/rustc_codegen_llvm/src/back/write.rs52
-rw-r--r--compiler/rustc_codegen_llvm/src/base.rs3
-rw-r--r--compiler/rustc_codegen_llvm/src/builder.rs57
-rw-r--r--compiler/rustc_codegen_llvm/src/builder/autodiff.rs426
-rw-r--r--compiler/rustc_codegen_llvm/src/common.rs10
-rw-r--r--compiler/rustc_codegen_llvm/src/consts.rs3
-rw-r--r--compiler/rustc_codegen_llvm/src/context.rs41
-rw-r--r--compiler/rustc_codegen_llvm/src/debuginfo/gdb.rs2
-rw-r--r--compiler/rustc_codegen_llvm/src/debuginfo/metadata/type_map.rs54
-rw-r--r--compiler/rustc_codegen_llvm/src/debuginfo/mod.rs43
-rw-r--r--compiler/rustc_codegen_llvm/src/debuginfo/namespace.rs2
-rw-r--r--compiler/rustc_codegen_llvm/src/intrinsic.rs160
-rw-r--r--compiler/rustc_codegen_llvm/src/lib.rs47
-rw-r--r--compiler/rustc_codegen_llvm/src/llvm/archive_ro.rs94
-rw-r--r--compiler/rustc_codegen_llvm/src/llvm/ffi.rs141
-rw-r--r--compiler/rustc_codegen_llvm/src/llvm/mod.rs73
-rw-r--r--compiler/rustc_codegen_llvm/src/llvm_util.rs5
-rw-r--r--compiler/rustc_codegen_llvm/src/mono_item.rs5
-rw-r--r--compiler/rustc_codegen_llvm/src/type_.rs14
-rw-r--r--compiler/rustc_codegen_ssa/Cargo.toml9
-rw-r--r--compiler/rustc_codegen_ssa/messages.ftl3
-rw-r--r--compiler/rustc_codegen_ssa/src/back/apple.rs2
-rw-r--r--compiler/rustc_codegen_ssa/src/back/link.rs16
-rw-r--r--compiler/rustc_codegen_ssa/src/back/link/raw_dylib.rs15
-rw-r--r--compiler/rustc_codegen_ssa/src/back/metadata.rs12
-rw-r--r--compiler/rustc_codegen_ssa/src/back/symbol_export.rs3
-rw-r--r--compiler/rustc_codegen_ssa/src/back/write.rs127
-rw-r--r--compiler/rustc_codegen_ssa/src/base.rs65
-rw-r--r--compiler/rustc_codegen_ssa/src/codegen_attrs.rs220
-rw-r--r--compiler/rustc_codegen_ssa/src/common.rs3
-rw-r--r--compiler/rustc_codegen_ssa/src/errors.rs8
-rw-r--r--compiler/rustc_codegen_ssa/src/lib.rs5
-rw-r--r--compiler/rustc_codegen_ssa/src/mir/block.rs34
-rw-r--r--compiler/rustc_codegen_ssa/src/mir/naked_asm.rs4
-rw-r--r--compiler/rustc_codegen_ssa/src/mono_item.rs3
-rw-r--r--compiler/rustc_codegen_ssa/src/target_features.rs13
-rw-r--r--compiler/rustc_codegen_ssa/src/traits/declare.rs3
-rw-r--r--compiler/rustc_codegen_ssa/src/traits/write.rs14
-rw-r--r--compiler/rustc_const_eval/Cargo.toml2
-rw-r--r--compiler/rustc_const_eval/messages.ftl11
-rw-r--r--compiler/rustc_const_eval/src/check_consts/check.rs6
-rw-r--r--compiler/rustc_const_eval/src/const_eval/eval_queries.rs7
-rw-r--r--compiler/rustc_const_eval/src/const_eval/machine.rs120
-rw-r--r--compiler/rustc_const_eval/src/errors.rs16
-rw-r--r--compiler/rustc_const_eval/src/interpret/call.rs37
-rw-r--r--compiler/rustc_const_eval/src/interpret/cast.rs34
-rw-r--r--compiler/rustc_const_eval/src/interpret/eval_context.rs5
-rw-r--r--compiler/rustc_const_eval/src/interpret/intern.rs97
-rw-r--r--compiler/rustc_const_eval/src/interpret/memory.rs44
-rw-r--r--compiler/rustc_const_eval/src/interpret/operand.rs10
-rw-r--r--compiler/rustc_const_eval/src/interpret/place.rs21
-rw-r--r--compiler/rustc_const_eval/src/interpret/stack.rs5
-rw-r--r--compiler/rustc_const_eval/src/interpret/step.rs84
-rw-r--r--compiler/rustc_const_eval/src/interpret/validity.rs8
-rw-r--r--compiler/rustc_const_eval/src/util/type_name.rs81
-rw-r--r--compiler/rustc_data_structures/Cargo.toml10
-rw-r--r--compiler/rustc_data_structures/src/lib.rs1
-rw-r--r--compiler/rustc_data_structures/src/union_find.rs (renamed from compiler/rustc_mir_transform/src/coverage/counters/union_find.rs)10
-rw-r--r--compiler/rustc_data_structures/src/union_find/tests.rs (renamed from compiler/rustc_mir_transform/src/coverage/counters/union_find/tests.rs)0
-rw-r--r--compiler/rustc_driver_impl/Cargo.toml2
-rw-r--r--compiler/rustc_error_codes/src/error_codes/E0458.md4
-rw-r--r--compiler/rustc_error_codes/src/error_codes/E0518.md4
-rw-r--r--compiler/rustc_error_codes/src/error_codes/E0578.md4
-rw-r--r--compiler/rustc_error_codes/src/error_codes/E0701.md4
-rw-r--r--compiler/rustc_error_codes/src/error_codes/E0739.md4
-rw-r--r--compiler/rustc_error_codes/src/error_codes/E0755.md4
-rw-r--r--compiler/rustc_error_codes/src/error_codes/E0756.md4
-rw-r--r--compiler/rustc_error_codes/src/error_codes/E0788.md4
-rw-r--r--compiler/rustc_error_codes/src/error_codes/E0793.md34
-rw-r--r--compiler/rustc_error_messages/Cargo.toml9
-rw-r--r--compiler/rustc_error_messages/src/diagnostic_impls.rs205
-rw-r--r--compiler/rustc_error_messages/src/lib.rs78
-rw-r--r--compiler/rustc_errors/Cargo.toml6
-rw-r--r--compiler/rustc_errors/src/codes.rs2
-rw-r--r--compiler/rustc_errors/src/decorate_diag.rs85
-rw-r--r--compiler/rustc_errors/src/diagnostic.rs89
-rw-r--r--compiler/rustc_errors/src/diagnostic_impls.rs303
-rw-r--r--compiler/rustc_errors/src/emitter.rs93
-rw-r--r--compiler/rustc_errors/src/lib.rs26
-rw-r--r--compiler/rustc_expand/Cargo.toml4
-rw-r--r--compiler/rustc_expand/messages.ftl2
-rw-r--r--compiler/rustc_expand/src/base.rs52
-rw-r--r--compiler/rustc_expand/src/config.rs14
-rw-r--r--compiler/rustc_expand/src/errors.rs1
-rw-r--r--compiler/rustc_expand/src/expand.rs93
-rw-r--r--compiler/rustc_expand/src/mbe/diagnostics.rs36
-rw-r--r--compiler/rustc_expand/src/mbe/macro_check.rs18
-rw-r--r--compiler/rustc_expand/src/mbe/macro_rules.rs204
-rw-r--r--compiler/rustc_expand/src/module.rs5
-rw-r--r--compiler/rustc_expand/src/proc_macro_server.rs16
-rw-r--r--compiler/rustc_feature/src/accepted.rs4
-rw-r--r--compiler/rustc_feature/src/builtin_attrs.rs25
-rw-r--r--compiler/rustc_feature/src/removed.rs3
-rw-r--r--compiler/rustc_feature/src/unstable.rs13
-rw-r--r--compiler/rustc_hir/Cargo.toml7
-rw-r--r--compiler/rustc_hir/src/attrs/data_structures.rs198
-rw-r--r--compiler/rustc_hir/src/attrs/encode_cross_crate.rs12
-rw-r--r--compiler/rustc_hir/src/attrs/pretty_printing.rs13
-rw-r--r--compiler/rustc_hir/src/def.rs73
-rw-r--r--compiler/rustc_hir/src/hir.rs41
-rw-r--r--compiler/rustc_hir/src/lang_items.rs4
-rw-r--r--compiler/rustc_hir/src/lib.rs6
-rw-r--r--compiler/rustc_hir/src/lints.rs4
-rw-r--r--compiler/rustc_hir/src/stable_hash_impls.rs21
-rw-r--r--compiler/rustc_hir/src/target.rs154
-rw-r--r--compiler/rustc_hir/src/version.rs8
-rw-r--r--compiler/rustc_hir_analysis/Cargo.toml4
-rw-r--r--compiler/rustc_hir_analysis/messages.ftl4
-rw-r--r--compiler/rustc_hir_analysis/src/check/check.rs26
-rw-r--r--compiler/rustc_hir_analysis/src/check/compare_impl_item.rs6
-rw-r--r--compiler/rustc_hir_analysis/src/check/intrinsic.rs8
-rw-r--r--compiler/rustc_hir_analysis/src/check/mod.rs1
-rw-r--r--compiler/rustc_hir_analysis/src/check/wfcheck.rs3
-rw-r--r--compiler/rustc_hir_analysis/src/collect/type_of/opaque.rs21
-rw-r--r--compiler/rustc_hir_analysis/src/errors.rs11
-rw-r--r--compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs34
-rw-r--r--compiler/rustc_hir_analysis/src/lib.rs2
-rw-r--r--compiler/rustc_hir_id/Cargo.toml13
-rw-r--r--compiler/rustc_hir_id/src/lib.rs (renamed from compiler/rustc_hir/src/hir_id.rs)31
-rw-r--r--compiler/rustc_hir_typeck/Cargo.toml4
-rw-r--r--compiler/rustc_hir_typeck/src/callee.rs7
-rw-r--r--compiler/rustc_hir_typeck/src/expr.rs3
-rw-r--r--compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs8
-rw-r--r--compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs16
-rw-r--r--compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs9
-rw-r--r--compiler/rustc_hir_typeck/src/intrinsicck.rs211
-rw-r--r--compiler/rustc_hir_typeck/src/lib.rs33
-rw-r--r--compiler/rustc_hir_typeck/src/method/probe.rs57
-rw-r--r--compiler/rustc_hir_typeck/src/method/suggest.rs123
-rw-r--r--compiler/rustc_hir_typeck/src/opaque_types.rs215
-rw-r--r--compiler/rustc_hir_typeck/src/upvar.rs2
-rw-r--r--compiler/rustc_hir_typeck/src/writeback.rs77
-rw-r--r--compiler/rustc_incremental/Cargo.toml4
-rw-r--r--compiler/rustc_index/src/bit_set.rs253
-rw-r--r--compiler/rustc_index/src/bit_set/tests.rs56
-rw-r--r--compiler/rustc_infer/Cargo.toml4
-rw-r--r--compiler/rustc_infer/src/infer/context.rs4
-rw-r--r--compiler/rustc_infer/src/infer/mod.rs25
-rw-r--r--compiler/rustc_interface/Cargo.toml2
-rw-r--r--compiler/rustc_interface/src/interface.rs4
-rw-r--r--compiler/rustc_interface/src/passes.rs34
-rw-r--r--compiler/rustc_interface/src/tests.rs5
-rw-r--r--compiler/rustc_interface/src/util.rs15
-rw-r--r--compiler/rustc_lexer/Cargo.toml8
-rw-r--r--compiler/rustc_lexer/src/lib.rs4
-rw-r--r--compiler/rustc_lint/Cargo.toml2
-rw-r--r--compiler/rustc_lint/messages.ftl36
-rw-r--r--compiler/rustc_lint/src/builtin.rs2
-rw-r--r--compiler/rustc_lint/src/context.rs38
-rw-r--r--compiler/rustc_lint/src/drop_forget_useless.rs2
-rw-r--r--compiler/rustc_lint/src/early.rs10
-rw-r--r--compiler/rustc_lint/src/early/diagnostics.rs51
-rw-r--r--compiler/rustc_lint/src/foreign_modules.rs2
-rw-r--r--compiler/rustc_lint/src/internal.rs137
-rw-r--r--compiler/rustc_lint/src/lib.rs5
-rw-r--r--compiler/rustc_lint/src/lifetime_syntax.rs8
-rw-r--r--compiler/rustc_lint/src/lints.rs151
-rw-r--r--compiler/rustc_lint/src/non_local_def.rs4
-rw-r--r--compiler/rustc_lint/src/nonstandard_style.rs52
-rw-r--r--compiler/rustc_lint/src/pass_by_value.rs6
-rw-r--r--compiler/rustc_lint/src/transmute.rs98
-rw-r--r--compiler/rustc_lint/src/types.rs5
-rw-r--r--compiler/rustc_lint_defs/Cargo.toml3
-rw-r--r--compiler/rustc_lint_defs/src/builtin.rs45
-rw-r--r--compiler/rustc_lint_defs/src/lib.rs92
-rw-r--r--compiler/rustc_llvm/build.rs1
-rw-r--r--compiler/rustc_llvm/llvm-wrapper/ArchiveWrapper.cpp208
-rw-r--r--compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp113
-rw-r--r--compiler/rustc_log/Cargo.toml2
-rw-r--r--compiler/rustc_macros/src/diagnostics/utils.rs2
-rw-r--r--compiler/rustc_macros/src/print_attribute.rs60
-rw-r--r--compiler/rustc_metadata/Cargo.toml4
-rw-r--r--compiler/rustc_metadata/messages.ftl95
-rw-r--r--compiler/rustc_metadata/src/creader.rs5
-rw-r--r--compiler/rustc_metadata/src/errors.rs217
-rw-r--r--compiler/rustc_metadata/src/native_libs.rs337
-rw-r--r--compiler/rustc_metadata/src/rmeta/decoder.rs16
-rw-r--r--compiler/rustc_metadata/src/rmeta/encoder.rs2
-rw-r--r--compiler/rustc_metadata/src/rmeta/mod.rs2
-rw-r--r--compiler/rustc_metadata/src/rmeta/table.rs26
-rw-r--r--compiler/rustc_middle/Cargo.toml6
-rw-r--r--compiler/rustc_middle/src/lib.rs1
-rw-r--r--compiler/rustc_middle/src/lint.rs29
-rw-r--r--compiler/rustc_middle/src/middle/codegen_fn_attrs.rs50
-rw-r--r--compiler/rustc_middle/src/middle/privacy.rs6
-rw-r--r--compiler/rustc_middle/src/middle/stability.rs4
-rw-r--r--compiler/rustc_middle/src/mir/consts.rs5
-rw-r--r--compiler/rustc_middle/src/mir/interpret/allocation.rs84
-rw-r--r--compiler/rustc_middle/src/mir/interpret/allocation/provenance_map.rs153
-rw-r--r--compiler/rustc_middle/src/mir/interpret/error.rs3
-rw-r--r--compiler/rustc_middle/src/mir/interpret/pointer.rs12
-rw-r--r--compiler/rustc_middle/src/mir/mod.rs42
-rw-r--r--compiler/rustc_middle/src/mir/mono.rs106
-rw-r--r--compiler/rustc_middle/src/mir/pretty.rs13
-rw-r--r--compiler/rustc_middle/src/mir/query.rs11
-rw-r--r--compiler/rustc_middle/src/mir/statement.rs36
-rw-r--r--compiler/rustc_middle/src/mir/syntax.rs5
-rw-r--r--compiler/rustc_middle/src/mir/visit.rs9
-rw-r--r--compiler/rustc_middle/src/query/erase.rs1
-rw-r--r--compiler/rustc_middle/src/query/mod.rs33
-rw-r--r--compiler/rustc_middle/src/query/on_disk_cache.rs51
-rw-r--r--compiler/rustc_middle/src/thir.rs70
-rw-r--r--compiler/rustc_middle/src/traits/mod.rs23
-rw-r--r--compiler/rustc_middle/src/ty/consts/valtree.rs15
-rw-r--r--compiler/rustc_middle/src/ty/context.rs9
-rw-r--r--compiler/rustc_middle/src/ty/diagnostics.rs4
-rw-r--r--compiler/rustc_middle/src/ty/mod.rs49
-rw-r--r--compiler/rustc_middle/src/ty/print/mod.rs92
-rw-r--r--compiler/rustc_middle/src/ty/print/pretty.rs123
-rw-r--r--compiler/rustc_middle/src/ty/structural_impls.rs13
-rw-r--r--compiler/rustc_middle/src/ty/sty.rs40
-rw-r--r--compiler/rustc_middle/src/ty/trait_def.rs7
-rw-r--r--compiler/rustc_middle/src/ty/typeck_results.rs17
-rw-r--r--compiler/rustc_mir_build/Cargo.toml4
-rw-r--r--compiler/rustc_mir_build/src/builder/coverageinfo.rs15
-rw-r--r--compiler/rustc_mir_build/src/builder/custom/mod.rs65
-rw-r--r--compiler/rustc_mir_build/src/builder/custom/parse/instruction.rs2
-rw-r--r--compiler/rustc_mir_build/src/builder/matches/mod.rs20
-rw-r--r--compiler/rustc_mir_build/src/builder/matches/test.rs68
-rw-r--r--compiler/rustc_mir_build/src/builder/mod.rs31
-rw-r--r--compiler/rustc_mir_build/src/check_tail_calls.rs34
-rw-r--r--compiler/rustc_mir_build/src/check_unsafety.rs9
-rw-r--r--compiler/rustc_mir_build/src/thir/cx/mod.rs10
-rw-r--r--compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs16
-rw-r--r--compiler/rustc_mir_build/src/thir/pattern/mod.rs8
-rw-r--r--compiler/rustc_mir_build/src/thir/print.rs2
-rw-r--r--compiler/rustc_mir_dataflow/Cargo.toml3
-rw-r--r--compiler/rustc_mir_dataflow/src/framework/graphviz.rs2
-rw-r--r--compiler/rustc_mir_dataflow/src/move_paths/abs_domain.rs38
-rw-r--r--compiler/rustc_mir_dataflow/src/move_paths/builder.rs5
-rw-r--r--compiler/rustc_mir_dataflow/src/move_paths/mod.rs17
-rw-r--r--compiler/rustc_mir_dataflow/src/rustc_peek.rs2
-rw-r--r--compiler/rustc_mir_transform/Cargo.toml4
-rw-r--r--compiler/rustc_mir_transform/src/check_call_recursion.rs4
-rw-r--r--compiler/rustc_mir_transform/src/check_enums.rs15
-rw-r--r--compiler/rustc_mir_transform/src/check_packed_ref.rs2
-rw-r--r--compiler/rustc_mir_transform/src/coverage/counters.rs1
-rw-r--r--compiler/rustc_mir_transform/src/coverage/counters/node_flow.rs3
-rw-r--r--compiler/rustc_mir_transform/src/coverage/mappings.rs60
-rw-r--r--compiler/rustc_mir_transform/src/coverage/mod.rs36
-rw-r--r--compiler/rustc_mir_transform/src/coverage/spans.rs12
-rw-r--r--compiler/rustc_mir_transform/src/gvn.rs62
-rw-r--r--compiler/rustc_mir_transform/src/pass_manager.rs45
-rw-r--r--compiler/rustc_mir_transform/src/ref_prop.rs39
-rw-r--r--compiler/rustc_mir_transform/src/shim.rs2
-rw-r--r--compiler/rustc_monomorphize/Cargo.toml4
-rw-r--r--compiler/rustc_monomorphize/src/collector.rs35
-rw-r--r--compiler/rustc_monomorphize/src/collector/autodiff.rs48
-rw-r--r--compiler/rustc_monomorphize/src/partitioning.rs51
-rw-r--r--compiler/rustc_monomorphize/src/partitioning/autodiff.rs143
-rw-r--r--compiler/rustc_next_trait_solver/Cargo.toml2
-rw-r--r--compiler/rustc_next_trait_solver/src/canonicalizer.rs35
-rw-r--r--compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs99
-rw-r--r--compiler/rustc_next_trait_solver/src/solve/assembly/structural_traits.rs24
-rw-r--r--compiler/rustc_next_trait_solver/src/solve/effect_goals.rs18
-rw-r--r--compiler/rustc_next_trait_solver/src/solve/eval_ctxt/canonical.rs2
-rw-r--r--compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs36
-rw-r--r--compiler/rustc_next_trait_solver/src/solve/eval_ctxt/probe.rs18
-rw-r--r--compiler/rustc_next_trait_solver/src/solve/mod.rs26
-rw-r--r--compiler/rustc_next_trait_solver/src/solve/normalizes_to/opaque_types.rs174
-rw-r--r--compiler/rustc_next_trait_solver/src/solve/trait_goals.rs72
-rw-r--r--compiler/rustc_parse/Cargo.toml9
-rw-r--r--compiler/rustc_parse/messages.ftl36
-rw-r--r--compiler/rustc_parse/src/errors.rs160
-rw-r--r--compiler/rustc_parse/src/lexer/mod.rs21
-rw-r--r--compiler/rustc_parse/src/lib.rs33
-rw-r--r--compiler/rustc_parse/src/parser/attr.rs5
-rw-r--r--compiler/rustc_parse/src/parser/cfg_select.rs30
-rw-r--r--compiler/rustc_parse/src/parser/diagnostics.rs41
-rw-r--r--compiler/rustc_parse/src/parser/expr.rs28
-rw-r--r--compiler/rustc_parse/src/parser/generics.rs11
-rw-r--r--compiler/rustc_parse/src/parser/item.rs74
-rw-r--r--compiler/rustc_parse/src/parser/mod.rs98
-rw-r--r--compiler/rustc_parse/src/parser/pat.rs18
-rw-r--r--compiler/rustc_parse/src/parser/path.rs16
-rw-r--r--compiler/rustc_parse/src/parser/stmt.rs6
-rw-r--r--compiler/rustc_parse/src/parser/token_type.rs6
-rw-r--r--compiler/rustc_parse/src/parser/ty.rs191
-rw-r--r--compiler/rustc_parse_format/Cargo.toml2
-rw-r--r--compiler/rustc_passes/Cargo.toml2
-rw-r--r--compiler/rustc_passes/messages.ftl185
-rw-r--r--compiler/rustc_passes/src/check_attr.rs1256
-rw-r--r--compiler/rustc_passes/src/dead.rs31
-rw-r--r--compiler/rustc_passes/src/errors.rs356
-rw-r--r--compiler/rustc_passes/src/lang_items.rs2
-rw-r--r--compiler/rustc_passes/src/reachable.rs1
-rw-r--r--compiler/rustc_pattern_analysis/Cargo.toml2
-rw-r--r--compiler/rustc_pattern_analysis/src/rustc.rs98
-rw-r--r--compiler/rustc_pattern_analysis/src/rustc/print.rs22
-rw-r--r--compiler/rustc_privacy/Cargo.toml2
-rw-r--r--compiler/rustc_proc_macro/Cargo.toml2
-rw-r--r--compiler/rustc_public/Cargo.toml2
-rw-r--r--compiler/rustc_query_impl/Cargo.toml2
-rw-r--r--compiler/rustc_query_system/Cargo.toml2
-rw-r--r--compiler/rustc_resolve/Cargo.toml8
-rw-r--r--compiler/rustc_resolve/messages.ftl8
-rw-r--r--compiler/rustc_resolve/src/build_reduced_graph.rs67
-rw-r--r--compiler/rustc_resolve/src/def_collector.rs6
-rw-r--r--compiler/rustc_resolve/src/diagnostics.rs153
-rw-r--r--compiler/rustc_resolve/src/errors.rs17
-rw-r--r--compiler/rustc_resolve/src/ident.rs221
-rw-r--r--compiler/rustc_resolve/src/imports.rs36
-rw-r--r--compiler/rustc_resolve/src/late.rs103
-rw-r--r--compiler/rustc_resolve/src/late/diagnostics.rs91
-rw-r--r--compiler/rustc_resolve/src/lib.rs177
-rw-r--r--compiler/rustc_resolve/src/macros.rs80
-rw-r--r--compiler/rustc_resolve/src/rustdoc.rs15
-rw-r--r--compiler/rustc_sanitizers/Cargo.toml4
-rw-r--r--compiler/rustc_serialize/Cargo.toml2
-rw-r--r--compiler/rustc_session/Cargo.toml8
-rw-r--r--compiler/rustc_session/messages.ftl6
-rw-r--r--compiler/rustc_session/src/config.rs54
-rw-r--r--compiler/rustc_session/src/config/cfg.rs5
-rw-r--r--compiler/rustc_session/src/config/native_libs.rs3
-rw-r--r--compiler/rustc_session/src/cstore.rs24
-rw-r--r--compiler/rustc_session/src/errors.rs16
-rw-r--r--compiler/rustc_session/src/options.rs4
-rw-r--r--compiler/rustc_session/src/parse.rs14
-rw-r--r--compiler/rustc_session/src/session.rs44
-rw-r--r--compiler/rustc_session/src/utils.rs64
-rw-r--r--compiler/rustc_span/Cargo.toml2
-rw-r--r--compiler/rustc_span/src/caching_source_map_view.rs30
-rw-r--r--compiler/rustc_span/src/source_map.rs24
-rw-r--r--compiler/rustc_span/src/span_encoding.rs5
-rw-r--r--compiler/rustc_span/src/symbol.rs116
-rw-r--r--compiler/rustc_symbol_mangling/Cargo.toml2
-rw-r--r--compiler/rustc_symbol_mangling/src/legacy.rs39
-rw-r--r--compiler/rustc_symbol_mangling/src/lib.rs87
-rw-r--r--compiler/rustc_symbol_mangling/src/v0.rs28
-rw-r--r--compiler/rustc_target/Cargo.toml12
-rw-r--r--compiler/rustc_target/src/callconv/mod.rs9
-rw-r--r--compiler/rustc_target/src/spec/json.rs3
-rw-r--r--compiler/rustc_target/src/spec/mod.rs20
-rw-r--r--compiler/rustc_target/src/spec/targets/aarch64_be_unknown_hermit.rs25
-rw-r--r--compiler/rustc_target/src/spec/targets/aarch64_be_unknown_linux_musl.rs40
-rw-r--r--compiler/rustc_target/src/spec/targets/aarch64_be_unknown_none_softfloat.rs43
-rw-r--r--compiler/rustc_target/src/spec/targets/aarch64_nintendo_switch_freestanding.rs2
-rw-r--r--compiler/rustc_target/src/spec/targets/armv7a_vex_v5_linker_script.ld27
-rw-r--r--compiler/rustc_target/src/spec/targets/avr_none.rs2
-rw-r--r--compiler/rustc_target/src/spec/targets/riscv64a23_unknown_linux_gnu.rs27
-rw-r--r--compiler/rustc_target/src/spec/targets/x86_64_apple_darwin.rs2
-rw-r--r--compiler/rustc_target/src/target_features.rs52
-rw-r--r--compiler/rustc_thread_pool/src/lib.rs15
-rw-r--r--compiler/rustc_trait_selection/Cargo.toml6
-rw-r--r--compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs91
-rw-r--r--compiler/rustc_trait_selection/src/error_reporting/infer/note_and_explain.rs4
-rw-r--r--compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs73
-rw-r--r--compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs2
-rw-r--r--compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs114
-rw-r--r--compiler/rustc_trait_selection/src/opaque_types.rs55
-rw-r--r--compiler/rustc_trait_selection/src/solve/fulfill.rs4
-rw-r--r--compiler/rustc_trait_selection/src/traits/dyn_compatibility.rs27
-rw-r--r--compiler/rustc_trait_selection/src/traits/project.rs2
-rw-r--r--compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs9
-rw-r--r--compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs16
-rw-r--r--compiler/rustc_trait_selection/src/traits/select/mod.rs61
-rw-r--r--compiler/rustc_trait_selection/src/traits/util.rs8
-rw-r--r--compiler/rustc_traits/Cargo.toml3
-rw-r--r--compiler/rustc_traits/src/coroutine_witnesses.rs2
-rw-r--r--compiler/rustc_traits/src/dropck_outlives.rs2
-rw-r--r--compiler/rustc_transmute/Cargo.toml4
-rw-r--r--compiler/rustc_ty_utils/Cargo.toml4
-rw-r--r--compiler/rustc_ty_utils/src/abi.rs1
-rw-r--r--compiler/rustc_type_ir/Cargo.toml8
-rw-r--r--compiler/rustc_type_ir/src/infer_ctxt.rs4
-rw-r--r--compiler/rustc_type_ir/src/inherent.rs6
-rw-r--r--compiler/rustc_type_ir/src/ir_print.rs49
-rw-r--r--compiler/rustc_type_ir/src/region_kind.rs2
-rw-r--r--compiler/rustc_type_ir/src/search_graph/mod.rs401
-rw-r--r--compiler/rustc_type_ir/src/search_graph/stack.rs45
514 files changed, 13525 insertions, 11671 deletions
diff --git a/compiler/rustc_abi/Cargo.toml b/compiler/rustc_abi/Cargo.toml
index 5f9afc46a1a..3de6d186b8a 100644
--- a/compiler/rustc_abi/Cargo.toml
+++ b/compiler/rustc_abi/Cargo.toml
@@ -5,16 +5,17 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-bitflags = "2.4.1"
+bitflags.workspace = true
 rand = { version = "0.9.0", default-features = false, optional = true }
 rand_xoshiro = { version = "0.7.0", optional = true }
 rustc_data_structures = { path = "../rustc_data_structures", optional = true }
+rustc_error_messages = { path = "../rustc_error_messages", optional = true }
 rustc_hashes = { path = "../rustc_hashes" }
 rustc_index = { path = "../rustc_index", default-features = false }
 rustc_macros = { path = "../rustc_macros", optional = true }
 rustc_serialize = { path = "../rustc_serialize", optional = true }
 rustc_span = { path = "../rustc_span", optional = true }
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
 
 [features]
@@ -24,6 +25,7 @@ default = ["nightly", "randomize"]
 # without depending on rustc_data_structures, rustc_macros and rustc_serialize
 nightly = [
     "dep:rustc_data_structures",
+    "dep:rustc_error_messages",
     "dep:rustc_macros",
     "dep:rustc_serialize",
     "dep:rustc_span",
diff --git a/compiler/rustc_abi/src/extern_abi.rs b/compiler/rustc_abi/src/extern_abi.rs
index 29a3678abf3..41d744e1946 100644
--- a/compiler/rustc_abi/src/extern_abi.rs
+++ b/compiler/rustc_abi/src/extern_abi.rs
@@ -223,6 +223,9 @@ impl StableOrd for ExternAbi {
     const THIS_IMPLEMENTATION_HAS_BEEN_TRIPLE_CHECKED: () = ();
 }
 
+#[cfg(feature = "nightly")]
+rustc_error_messages::into_diag_arg_using_display!(ExternAbi);
+
 impl ExternAbi {
     /// An ABI "like Rust"
     ///
diff --git a/compiler/rustc_ast/Cargo.toml b/compiler/rustc_ast/Cargo.toml
index 155e14a3796..0b8ab7c391c 100644
--- a/compiler/rustc_ast/Cargo.toml
+++ b/compiler/rustc_ast/Cargo.toml
@@ -5,9 +5,9 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-bitflags = "2.4.1"
-memchr = "2.7.4"
-rustc-literal-escaper = "0.0.5"
+bitflags.workspace = true
+memchr.workspace = true
+rustc-literal-escaper.workspace = true
 rustc_ast_ir = { path = "../rustc_ast_ir" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_index = { path = "../rustc_index" }
@@ -15,6 +15,6 @@ rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_span = { path = "../rustc_span" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec = "0.2.12"
+thin-vec.workspace = true
 tracing = "0.1"
 # tidy-alphabetical-end
diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs
index 87c9c797ea5..de3e0e0c87f 100644
--- a/compiler/rustc_ast/src/ast.rs
+++ b/compiler/rustc_ast/src/ast.rs
@@ -3137,7 +3137,7 @@ impl FnRetTy {
 #[derive(Clone, Copy, PartialEq, Encodable, Decodable, Debug, Walkable)]
 pub enum Inline {
     Yes,
-    No,
+    No { had_parse_error: Result<(), ErrorGuaranteed> },
 }
 
 /// Module item kind.
@@ -3147,7 +3147,7 @@ pub enum ModKind {
     /// or with definition outlined to a separate file `mod foo;` and already loaded from it.
     /// The inner span is from the first token past `{` to the last token until `}`,
     /// or from the first to the last token in the loaded file.
-    Loaded(ThinVec<Box<Item>>, Inline, ModSpans, Result<(), ErrorGuaranteed>),
+    Loaded(ThinVec<Box<Item>>, Inline, ModSpans),
     /// Module with definition outlined to a separate file `mod foo;` but not yet loaded from it.
     Unloaded,
 }
diff --git a/compiler/rustc_ast/src/token.rs b/compiler/rustc_ast/src/token.rs
index fc816f2cb79..ea98bebd305 100644
--- a/compiler/rustc_ast/src/token.rs
+++ b/compiler/rustc_ast/src/token.rs
@@ -7,6 +7,7 @@ pub use NtPatKind::*;
 pub use TokenKind::*;
 use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use rustc_span::edition::Edition;
+use rustc_span::symbol::IdentPrintMode;
 use rustc_span::{DUMMY_SP, ErrorGuaranteed, Span, kw, sym};
 #[allow(clippy::useless_attribute)] // FIXME: following use of `hidden_glob_reexports` incorrectly triggers `useless_attribute` lint.
 #[allow(hidden_glob_reexports)]
@@ -344,15 +345,24 @@ pub enum IdentIsRaw {
     Yes,
 }
 
-impl From<bool> for IdentIsRaw {
-    fn from(b: bool) -> Self {
-        if b { Self::Yes } else { Self::No }
+impl IdentIsRaw {
+    pub fn to_print_mode_ident(self) -> IdentPrintMode {
+        match self {
+            IdentIsRaw::No => IdentPrintMode::Normal,
+            IdentIsRaw::Yes => IdentPrintMode::RawIdent,
+        }
+    }
+    pub fn to_print_mode_lifetime(self) -> IdentPrintMode {
+        match self {
+            IdentIsRaw::No => IdentPrintMode::Normal,
+            IdentIsRaw::Yes => IdentPrintMode::RawLifetime,
+        }
     }
 }
 
-impl From<IdentIsRaw> for bool {
-    fn from(is_raw: IdentIsRaw) -> bool {
-        matches!(is_raw, IdentIsRaw::Yes)
+impl From<bool> for IdentIsRaw {
+    fn from(b: bool) -> Self {
+        if b { Self::Yes } else { Self::No }
     }
 }
 
diff --git a/compiler/rustc_ast/src/tokenstream.rs b/compiler/rustc_ast/src/tokenstream.rs
index e55399adfb8..f4f35a4d2ee 100644
--- a/compiler/rustc_ast/src/tokenstream.rs
+++ b/compiler/rustc_ast/src/tokenstream.rs
@@ -907,6 +907,12 @@ impl TokenTreeCursor {
     pub fn bump(&mut self) {
         self.index += 1;
     }
+
+    // For skipping ahead in rare circumstances.
+    #[inline]
+    pub fn bump_to_end(&mut self) {
+        self.index = self.stream.len();
+    }
 }
 
 /// A `TokenStream` cursor that produces `Token`s. It's a bit odd that
diff --git a/compiler/rustc_ast_lowering/Cargo.toml b/compiler/rustc_ast_lowering/Cargo.toml
index 6ac258155fe..317742a3bb8 100644
--- a/compiler/rustc_ast_lowering/Cargo.toml
+++ b/compiler/rustc_ast_lowering/Cargo.toml
@@ -24,6 +24,6 @@ rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec = "0.2.12"
-tracing = "0.1"
+thin-vec.workspace = true
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_ast_lowering/src/block.rs b/compiler/rustc_ast_lowering/src/block.rs
index 2cc07694afb..f1e810a8b9e 100644
--- a/compiler/rustc_ast_lowering/src/block.rs
+++ b/compiler/rustc_ast_lowering/src/block.rs
@@ -1,5 +1,6 @@
 use rustc_ast::{Block, BlockCheckMode, Local, LocalKind, Stmt, StmtKind};
 use rustc_hir as hir;
+use rustc_hir::Target;
 use rustc_span::sym;
 use smallvec::SmallVec;
 
@@ -109,7 +110,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         };
         let span = self.lower_span(l.span);
         let source = hir::LocalSource::Normal;
-        self.lower_attrs(hir_id, &l.attrs, l.span);
+        self.lower_attrs(hir_id, &l.attrs, l.span, Target::Statement);
         self.arena.alloc(hir::LetStmt { hir_id, super_, ty, pat, init, els, span, source })
     }
 
diff --git a/compiler/rustc_ast_lowering/src/expr.rs b/compiler/rustc_ast_lowering/src/expr.rs
index 2ddbf083a09..cbd17d66b75 100644
--- a/compiler/rustc_ast_lowering/src/expr.rs
+++ b/compiler/rustc_ast_lowering/src/expr.rs
@@ -7,7 +7,7 @@ use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_hir as hir;
 use rustc_hir::attrs::AttributeKind;
 use rustc_hir::def::{DefKind, Res};
-use rustc_hir::{HirId, find_attr};
+use rustc_hir::{HirId, Target, find_attr};
 use rustc_middle::span_bug;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::errors::report_lit_error;
@@ -74,7 +74,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     if !e.attrs.is_empty() {
                         let old_attrs = self.attrs.get(&ex.hir_id.local_id).copied().unwrap_or(&[]);
                         let new_attrs = self
-                            .lower_attrs_vec(&e.attrs, e.span, ex.hir_id)
+                            .lower_attrs_vec(&e.attrs, e.span, ex.hir_id, Target::from_expr(e))
                             .into_iter()
                             .chain(old_attrs.iter().cloned());
                         let new_attrs = &*self.arena.alloc_from_iter(new_attrs);
@@ -97,7 +97,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             }
 
             let expr_hir_id = self.lower_node_id(e.id);
-            let attrs = self.lower_attrs(expr_hir_id, &e.attrs, e.span);
+            let attrs = self.lower_attrs(expr_hir_id, &e.attrs, e.span, Target::from_expr(e));
 
             let kind = match &e.kind {
                 ExprKind::Array(exprs) => hir::ExprKind::Array(self.lower_exprs(exprs)),
@@ -639,7 +639,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         let guard = arm.guard.as_ref().map(|cond| self.lower_expr(cond));
         let hir_id = self.next_id();
         let span = self.lower_span(arm.span);
-        self.lower_attrs(hir_id, &arm.attrs, arm.span);
+        self.lower_attrs(hir_id, &arm.attrs, arm.span, Target::Arm);
         let is_never_pattern = pat.is_never_pattern();
         // We need to lower the body even if it's unneeded for never pattern in match,
         // ensure that we can get HirId for DefId if need (issue #137708).
@@ -820,6 +820,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     span: unstable_span,
                 }],
                 span,
+                Target::Fn,
             );
         }
     }
@@ -1654,7 +1655,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
 
     fn lower_expr_field(&mut self, f: &ExprField) -> hir::ExprField<'hir> {
         let hir_id = self.lower_node_id(f.id);
-        self.lower_attrs(hir_id, &f.attrs, f.span);
+        self.lower_attrs(hir_id, &f.attrs, f.span, Target::ExprField);
         hir::ExprField {
             hir_id,
             ident: self.lower_ident(f.ident),
@@ -1910,7 +1911,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         //
         // Also, add the attributes to the outer returned expr node.
         let expr = self.expr_drop_temps_mut(for_span, match_expr);
-        self.lower_attrs(expr.hir_id, &e.attrs, e.span);
+        self.lower_attrs(expr.hir_id, &e.attrs, e.span, Target::from_expr(e));
         expr
     }
 
@@ -1967,7 +1968,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             let val_ident = Ident::with_dummy_span(sym::val);
             let (val_pat, val_pat_nid) = self.pat_ident(span, val_ident);
             let val_expr = self.expr_ident(span, val_ident, val_pat_nid);
-            self.lower_attrs(val_expr.hir_id, &attrs, span);
+            self.lower_attrs(val_expr.hir_id, &attrs, span, Target::Expression);
             let continue_pat = self.pat_cf_continue(unstable_span, val_pat);
             self.arm(continue_pat, val_expr)
         };
@@ -1998,7 +1999,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 let ret_expr = self.checked_return(Some(from_residual_expr));
                 self.arena.alloc(self.expr(try_span, ret_expr))
             };
-            self.lower_attrs(ret_expr.hir_id, &attrs, span);
+            self.lower_attrs(ret_expr.hir_id, &attrs, span, Target::Expression);
 
             let break_pat = self.pat_cf_break(try_span, residual_local);
             self.arm(break_pat, ret_expr)
diff --git a/compiler/rustc_ast_lowering/src/item.rs b/compiler/rustc_ast_lowering/src/item.rs
index 235573c96e4..bb559bd8921 100644
--- a/compiler/rustc_ast_lowering/src/item.rs
+++ b/compiler/rustc_ast_lowering/src/item.rs
@@ -5,7 +5,7 @@ use rustc_errors::{E0570, ErrorGuaranteed, struct_span_code_err};
 use rustc_hir::attrs::AttributeKind;
 use rustc_hir::def::{DefKind, PerNS, Res};
 use rustc_hir::def_id::{CRATE_DEF_ID, LocalDefId};
-use rustc_hir::{self as hir, HirId, LifetimeSource, PredicateOrigin, find_attr};
+use rustc_hir::{self as hir, HirId, LifetimeSource, PredicateOrigin, Target, find_attr};
 use rustc_index::{IndexSlice, IndexVec};
 use rustc_middle::span_bug;
 use rustc_middle::ty::{ResolverAstLowering, TyCtxt};
@@ -80,7 +80,7 @@ impl<'a, 'hir> ItemLowerer<'a, 'hir> {
                     self.with_lctx(CRATE_NODE_ID, |lctx| {
                         let module = lctx.lower_mod(&c.items, &c.spans);
                         // FIXME(jdonszelman): is dummy span ever a problem here?
-                        lctx.lower_attrs(hir::CRATE_HIR_ID, &c.attrs, DUMMY_SP);
+                        lctx.lower_attrs(hir::CRATE_HIR_ID, &c.attrs, DUMMY_SP, Target::Crate);
                         hir::OwnerNode::Crate(module)
                     })
                 }
@@ -136,7 +136,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
     fn lower_item(&mut self, i: &Item) -> &'hir hir::Item<'hir> {
         let vis_span = self.lower_span(i.vis.span);
         let hir_id = hir::HirId::make_owner(self.current_hir_id_owner.def_id);
-        let attrs = self.lower_attrs(hir_id, &i.attrs, i.span);
+        let attrs = self.lower_attrs(hir_id, &i.attrs, i.span, Target::from_ast_item(i));
         let kind = self.lower_item_kind(i.span, i.id, hir_id, attrs, vis_span, &i.kind);
         let item = hir::Item {
             owner_id: hir_id.expect_owner(),
@@ -251,7 +251,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             ItemKind::Mod(_, ident, mod_kind) => {
                 let ident = self.lower_ident(*ident);
                 match mod_kind {
-                    ModKind::Loaded(items, _, spans, _) => {
+                    ModKind::Loaded(items, _, spans) => {
                         hir::ItemKind::Mod(ident, self.lower_mod(items, spans))
                     }
                     ModKind::Unloaded => panic!("`mod` items should have been loaded by now"),
@@ -436,14 +436,14 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 let body = Box::new(self.lower_delim_args(body));
                 let def_id = self.local_def_id(id);
                 let def_kind = self.tcx.def_kind(def_id);
-                let DefKind::Macro(macro_kind) = def_kind else {
+                let DefKind::Macro(macro_kinds) = def_kind else {
                     unreachable!(
                         "expected DefKind::Macro for macro item, found {}",
                         def_kind.descr(def_id.to_def_id())
                     );
                 };
                 let macro_def = self.arena.alloc(ast::MacroDef { body, macro_rules: *macro_rules });
-                hir::ItemKind::Macro(ident, macro_def, macro_kind)
+                hir::ItemKind::Macro(ident, macro_def, macro_kinds)
             }
             ItemKind::Delegation(box delegation) => {
                 let delegation_results = self.lower_delegation(delegation, id, false);
@@ -621,7 +621,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
     fn lower_foreign_item(&mut self, i: &ForeignItem) -> &'hir hir::ForeignItem<'hir> {
         let hir_id = hir::HirId::make_owner(self.current_hir_id_owner.def_id);
         let owner_id = hir_id.expect_owner();
-        let attrs = self.lower_attrs(hir_id, &i.attrs, i.span);
+        let attrs =
+            self.lower_attrs(hir_id, &i.attrs, i.span, Target::from_foreign_item_kind(&i.kind));
         let (ident, kind) = match &i.kind {
             ForeignItemKind::Fn(box Fn { sig, ident, generics, define_opaque, .. }) => {
                 let fdec = &sig.decl;
@@ -690,7 +691,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
 
     fn lower_variant(&mut self, item_kind: &ItemKind, v: &Variant) -> hir::Variant<'hir> {
         let hir_id = self.lower_node_id(v.id);
-        self.lower_attrs(hir_id, &v.attrs, v.span);
+        self.lower_attrs(hir_id, &v.attrs, v.span, Target::Variant);
         hir::Variant {
             hir_id,
             def_id: self.local_def_id(v.id),
@@ -773,7 +774,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
     ) -> hir::FieldDef<'hir> {
         let ty = self.lower_ty(&f.ty, ImplTraitContext::Disallowed(ImplTraitPosition::FieldTy));
         let hir_id = self.lower_node_id(f.id);
-        self.lower_attrs(hir_id, &f.attrs, f.span);
+        self.lower_attrs(hir_id, &f.attrs, f.span, Target::Field);
         hir::FieldDef {
             span: self.lower_span(f.span),
             hir_id,
@@ -792,7 +793,12 @@ impl<'hir> LoweringContext<'_, 'hir> {
 
     fn lower_trait_item(&mut self, i: &AssocItem) -> &'hir hir::TraitItem<'hir> {
         let hir_id = hir::HirId::make_owner(self.current_hir_id_owner.def_id);
-        let attrs = self.lower_attrs(hir_id, &i.attrs, i.span);
+        let attrs = self.lower_attrs(
+            hir_id,
+            &i.attrs,
+            i.span,
+            Target::from_assoc_item_kind(&i.kind, AssocCtxt::Trait),
+        );
         let trait_item_def_id = hir_id.expect_owner();
 
         let (ident, generics, kind, has_default) = match &i.kind {
@@ -1001,7 +1007,12 @@ impl<'hir> LoweringContext<'_, 'hir> {
         let has_value = true;
         let (defaultness, _) = self.lower_defaultness(i.kind.defaultness(), has_value);
         let hir_id = hir::HirId::make_owner(self.current_hir_id_owner.def_id);
-        let attrs = self.lower_attrs(hir_id, &i.attrs, i.span);
+        let attrs = self.lower_attrs(
+            hir_id,
+            &i.attrs,
+            i.span,
+            Target::from_assoc_item_kind(&i.kind, AssocCtxt::Impl { of_trait: is_in_trait_impl }),
+        );
 
         let (ident, (generics, kind)) = match &i.kind {
             AssocItemKind::Const(box ConstItem {
@@ -1171,7 +1182,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
 
     fn lower_param(&mut self, param: &Param) -> hir::Param<'hir> {
         let hir_id = self.lower_node_id(param.id);
-        self.lower_attrs(hir_id, &param.attrs, param.span);
+        self.lower_attrs(hir_id, &param.attrs, param.span, Target::Param);
         hir::Param {
             hir_id,
             pat: self.lower_pat(&param.pat),
@@ -1585,7 +1596,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         let safety = self.lower_safety(h.safety, default_safety);
 
         // Treat safe `#[target_feature]` functions as unsafe, but also remember that we did so.
-        let safety = if find_attr!(attrs, AttributeKind::TargetFeature { .. })
+        let safety = if find_attr!(attrs, AttributeKind::TargetFeature { was_forced: false, .. })
             && safety.is_safe()
             && !self.tcx.sess.target.is_like_wasm
         {
@@ -1851,7 +1862,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
     ) -> hir::WherePredicate<'hir> {
         let hir_id = self.lower_node_id(pred.id);
         let span = self.lower_span(pred.span);
-        self.lower_attrs(hir_id, &pred.attrs, span);
+        self.lower_attrs(hir_id, &pred.attrs, span, Target::WherePredicate);
         let kind = self.arena.alloc(match &pred.kind {
             WherePredicateKind::BoundPredicate(WhereBoundPredicate {
                 bound_generic_params,
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index 465d9dc82bc..70595391b85 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -54,7 +54,7 @@ use rustc_hir::def_id::{CRATE_DEF_ID, LOCAL_CRATE, LocalDefId};
 use rustc_hir::lints::DelayedLint;
 use rustc_hir::{
     self as hir, AngleBrackets, ConstArg, GenericArg, HirId, ItemLocalMap, LifetimeSource,
-    LifetimeSyntax, ParamName, TraitCandidate,
+    LifetimeSyntax, ParamName, Target, TraitCandidate,
 };
 use rustc_index::{Idx, IndexSlice, IndexVec};
 use rustc_macros::extension;
@@ -943,11 +943,13 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         id: HirId,
         attrs: &[Attribute],
         target_span: Span,
+        target: Target,
     ) -> &'hir [hir::Attribute] {
         if attrs.is_empty() {
             &[]
         } else {
-            let lowered_attrs = self.lower_attrs_vec(attrs, self.lower_span(target_span), id);
+            let lowered_attrs =
+                self.lower_attrs_vec(attrs, self.lower_span(target_span), id, target);
 
             assert_eq!(id.owner, self.current_hir_id_owner);
             let ret = self.arena.alloc_from_iter(lowered_attrs);
@@ -972,12 +974,14 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         attrs: &[Attribute],
         target_span: Span,
         target_hir_id: HirId,
+        target: Target,
     ) -> Vec<hir::Attribute> {
         let l = self.span_lowerer();
         self.attribute_parser.parse_attribute_list(
             attrs,
             target_span,
             target_hir_id,
+            target,
             OmitDoc::Lower,
             |s| l.lower(s),
             |l| {
@@ -1942,7 +1946,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         let (name, kind) = self.lower_generic_param_kind(param, source);
 
         let hir_id = self.lower_node_id(param.id);
-        self.lower_attrs(hir_id, &param.attrs, param.span());
+        self.lower_attrs(hir_id, &param.attrs, param.span(), Target::Param);
         hir::GenericParam {
             hir_id,
             def_id: self.local_def_id(param.id),
diff --git a/compiler/rustc_ast_lowering/src/pat.rs b/compiler/rustc_ast_lowering/src/pat.rs
index b6533060a76..b8f86247875 100644
--- a/compiler/rustc_ast_lowering/src/pat.rs
+++ b/compiler/rustc_ast_lowering/src/pat.rs
@@ -3,7 +3,7 @@ use std::sync::Arc;
 use rustc_ast::*;
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_hir::def::{DefKind, Res};
-use rustc_hir::{self as hir, LangItem};
+use rustc_hir::{self as hir, LangItem, Target};
 use rustc_middle::span_bug;
 use rustc_span::source_map::{Spanned, respan};
 use rustc_span::{DesugaringKind, Ident, Span};
@@ -93,7 +93,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
 
                         let fs = self.arena.alloc_from_iter(fields.iter().map(|f| {
                             let hir_id = self.lower_node_id(f.id);
-                            self.lower_attrs(hir_id, &f.attrs, f.span);
+                            self.lower_attrs(hir_id, &f.attrs, f.span, Target::PatField);
 
                             hir::PatField {
                                 hir_id,
diff --git a/compiler/rustc_ast_passes/Cargo.toml b/compiler/rustc_ast_passes/Cargo.toml
index 1940628b44a..6d2bcbed22b 100644
--- a/compiler/rustc_ast_passes/Cargo.toml
+++ b/compiler/rustc_ast_passes/Cargo.toml
@@ -5,7 +5,7 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-itertools = "0.12"
+itertools.workspace = true
 rustc_abi = { path = "../rustc_abi" }
 rustc_ast = { path = "../rustc_ast" }
 rustc_ast_pretty = { path = "../rustc_ast_pretty" }
@@ -15,9 +15,8 @@ rustc_errors = { path = "../rustc_errors" }
 rustc_feature = { path = "../rustc_feature" }
 rustc_fluent_macro = { path = "../rustc_fluent_macro" }
 rustc_macros = { path = "../rustc_macros" }
-rustc_parse = { path = "../rustc_parse" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
-thin-vec = "0.2.12"
+thin-vec.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_ast_passes/messages.ftl b/compiler/rustc_ast_passes/messages.ftl
index 340a1a239c5..a95f1443968 100644
--- a/compiler/rustc_ast_passes/messages.ftl
+++ b/compiler/rustc_ast_passes/messages.ftl
@@ -17,9 +17,13 @@ ast_passes_abi_must_not_have_parameters_or_return_type=
 
 ast_passes_abi_must_not_have_return_type=
     invalid signature for `extern {$abi}` function
-    .note = functions with the "custom" ABI cannot have a return type
+    .note = functions with the {$abi} ABI cannot have a return type
     .help = remove the return type
 
+ast_passes_abi_x86_interrupt =
+    invalid signature for `extern "x86-interrupt"` function
+    .note = functions with the "x86-interrupt" ABI must be have either 1 or 2 parameters (but found {$param_count})
+
 ast_passes_assoc_const_without_body =
     associated constant in `impl` without body
     .suggestion = provide a definition for the constant
@@ -32,6 +36,13 @@ ast_passes_assoc_type_without_body =
     associated type in `impl` without body
     .suggestion = provide a definition for the type
 
+ast_passes_async_fn_in_const_trait_or_trait_impl =
+    async functions are not allowed in `const` {$in_impl ->
+        [true] trait impls
+        *[false] traits
+    }
+    .label = associated functions of `const` cannot be declared `async`
+
 ast_passes_at_least_one_trait = at least one trait must be specified
 
 ast_passes_auto_generic = auto traits cannot have generic parameters
@@ -102,6 +113,10 @@ ast_passes_extern_without_abi = `extern` declarations without an explicit ABI ar
     .suggestion = specify an ABI
     .help = prior to Rust 2024, a default ABI was inferred
 
+ast_passes_extern_without_abi_sugg = `extern` declarations without an explicit ABI are deprecated
+    .label = ABI should be specified here
+    .suggestion = explicitly specify the {$default_abi} ABI
+
 ast_passes_feature_on_non_nightly = `#![feature]` may not be used on the {$channel} release channel
     .suggestion = remove the attribute
     .stable_since = the feature `{$name}` has been stable since `{$since}` and no longer requires an attribute to enable
diff --git a/compiler/rustc_ast_passes/src/ast_validation.rs b/compiler/rustc_ast_passes/src/ast_validation.rs
index dc2eb17589c..6133cc3548b 100644
--- a/compiler/rustc_ast_passes/src/ast_validation.rs
+++ b/compiler/rustc_ast_passes/src/ast_validation.rs
@@ -25,16 +25,16 @@ use rustc_abi::{CanonAbi, ExternAbi, InterruptKind};
 use rustc_ast::visit::{AssocCtxt, BoundKind, FnCtxt, FnKind, Visitor, walk_list};
 use rustc_ast::*;
 use rustc_ast_pretty::pprust::{self, State};
+use rustc_attr_parsing::validate_attr;
 use rustc_data_structures::fx::FxIndexMap;
-use rustc_errors::DiagCtxtHandle;
+use rustc_errors::{DiagCtxtHandle, LintBuffer};
 use rustc_feature::Features;
-use rustc_parse::validate_attr;
 use rustc_session::Session;
+use rustc_session::lint::BuiltinLintDiag;
 use rustc_session::lint::builtin::{
     DEPRECATED_WHERE_CLAUSE_LOCATION, MISSING_ABI, MISSING_UNSAFE_ON_EXTERN,
     PATTERNS_IN_FNS_WITHOUT_BODY,
 };
-use rustc_session::lint::{BuiltinLintDiag, LintBuffer};
 use rustc_span::{Ident, Span, kw, sym};
 use rustc_target::spec::{AbiMap, AbiMapping};
 use thin_vec::thin_vec;
@@ -293,6 +293,21 @@ impl<'a> AstValidator<'a> {
         });
     }
 
+    fn check_async_fn_in_const_trait_or_impl(&self, sig: &FnSig, parent: &TraitOrTraitImpl) {
+        let Some(const_keyword) = parent.constness() else { return };
+
+        let Some(CoroutineKind::Async { span: async_keyword, .. }) = sig.header.coroutine_kind
+        else {
+            return;
+        };
+
+        self.dcx().emit_err(errors::AsyncFnInConstTraitOrTraitImpl {
+            async_keyword,
+            in_impl: matches!(parent, TraitOrTraitImpl::TraitImpl { .. }),
+            const_keyword,
+        });
+    }
+
     fn check_fn_decl(&self, fn_decl: &FnDecl, self_semantic: SelfSemantic) {
         self.check_decl_num_args(fn_decl);
         self.check_decl_cvariadic_pos(fn_decl);
@@ -390,7 +405,24 @@ impl<'a> AstValidator<'a> {
                         if let InterruptKind::X86 = interrupt_kind {
                             // "x86-interrupt" is special because it does have arguments.
                             // FIXME(workingjubilee): properly lint on acceptable input types.
-                            if let FnRetTy::Ty(ref ret_ty) = sig.decl.output {
+                            let inputs = &sig.decl.inputs;
+                            let param_count = inputs.len();
+                            if !matches!(param_count, 1 | 2) {
+                                let mut spans: Vec<Span> =
+                                    inputs.iter().map(|arg| arg.span).collect();
+                                if spans.is_empty() {
+                                    spans = vec![sig.span];
+                                }
+                                self.dcx().emit_err(errors::AbiX86Interrupt { spans, param_count });
+                            }
+
+                            if let FnRetTy::Ty(ref ret_ty) = sig.decl.output
+                                && match &ret_ty.kind {
+                                    TyKind::Never => false,
+                                    TyKind::Tup(tup) if tup.is_empty() => false,
+                                    _ => true,
+                                }
+                            {
                                 self.dcx().emit_err(errors::AbiMustNotHaveReturnType {
                                     span: ret_ty.span,
                                     abi,
@@ -449,7 +481,13 @@ impl<'a> AstValidator<'a> {
 
     fn reject_params_or_return(&self, abi: ExternAbi, ident: &Ident, sig: &FnSig) {
         let mut spans: Vec<_> = sig.decl.inputs.iter().map(|p| p.span).collect();
-        if let FnRetTy::Ty(ref ret_ty) = sig.decl.output {
+        if let FnRetTy::Ty(ref ret_ty) = sig.decl.output
+            && match &ret_ty.kind {
+                TyKind::Never => false,
+                TyKind::Tup(tup) if tup.is_empty() => false,
+                _ => true,
+            }
+        {
             spans.push(ret_ty.span);
         }
 
@@ -838,7 +876,7 @@ impl<'a> AstValidator<'a> {
                 MISSING_ABI,
                 id,
                 span,
-                BuiltinLintDiag::MissingAbi(span, ExternAbi::FALLBACK),
+                errors::MissingAbiSugg { span, default_abi: ExternAbi::FALLBACK },
             )
         }
     }
@@ -1142,7 +1180,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                     self.dcx().emit_err(errors::UnsafeItem { span, kind: "module" });
                 }
                 // Ensure that `path` attributes on modules are recorded as used (cf. issue #35584).
-                if !matches!(mod_kind, ModKind::Loaded(_, Inline::Yes, _, _))
+                if !matches!(mod_kind, ModKind::Loaded(_, Inline::Yes, _))
                     && !attr::contains_name(&item.attrs, sym::path)
                 {
                     self.check_mod_file_item_asciionly(*ident);
@@ -1566,6 +1604,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
             self.visibility_not_permitted(&item.vis, errors::VisibilityNotPermittedNote::TraitImpl);
             if let AssocItemKind::Fn(box Fn { sig, .. }) = &item.kind {
                 self.check_trait_fn_not_const(sig.header.constness, parent);
+                self.check_async_fn_in_const_trait_or_impl(sig, parent);
             }
         }
 
@@ -1741,7 +1780,7 @@ fn deny_equality_constraints(
                         .map(|segment| segment.ident.name)
                         .zip(poly.trait_ref.path.segments.iter().map(|segment| segment.ident.name))
                         .all(|(a, b)| a == b)
-                        && let Some(potential_assoc) = full_path.segments.iter().last()
+                        && let Some(potential_assoc) = full_path.segments.last()
                     {
                         suggest(poly, potential_assoc, predicate);
                     }
diff --git a/compiler/rustc_ast_passes/src/errors.rs b/compiler/rustc_ast_passes/src/errors.rs
index 1cb2493afe8..ae8f056cb4e 100644
--- a/compiler/rustc_ast_passes/src/errors.rs
+++ b/compiler/rustc_ast_passes/src/errors.rs
@@ -4,7 +4,7 @@ use rustc_abi::ExternAbi;
 use rustc_ast::ParamKindOrd;
 use rustc_errors::codes::*;
 use rustc_errors::{Applicability, Diag, EmissionGuarantee, Subdiagnostic};
-use rustc_macros::{Diagnostic, Subdiagnostic};
+use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
 use rustc_span::{Ident, Span, Symbol};
 
 use crate::fluent_generated as fluent;
@@ -63,6 +63,16 @@ pub(crate) struct TraitFnConst {
 }
 
 #[derive(Diagnostic)]
+#[diag(ast_passes_async_fn_in_const_trait_or_trait_impl)]
+pub(crate) struct AsyncFnInConstTraitOrTraitImpl {
+    #[primary_span]
+    pub async_keyword: Span,
+    pub in_impl: bool,
+    #[label]
+    pub const_keyword: Span,
+}
+
+#[derive(Diagnostic)]
 #[diag(ast_passes_forbidden_bound)]
 pub(crate) struct ForbiddenBound {
     #[primary_span]
@@ -805,6 +815,14 @@ pub(crate) struct MissingAbi {
     pub span: Span,
 }
 
+#[derive(LintDiagnostic)]
+#[diag(ast_passes_extern_without_abi_sugg)]
+pub(crate) struct MissingAbiSugg {
+    #[suggestion(code = "extern {default_abi}", applicability = "machine-applicable")]
+    pub span: Span,
+    pub default_abi: ExternAbi,
+}
+
 #[derive(Diagnostic)]
 #[diag(ast_passes_abi_custom_safe_foreign_function)]
 pub(crate) struct AbiCustomSafeForeignFunction {
@@ -881,3 +899,12 @@ pub(crate) struct AbiMustNotHaveReturnType {
     pub span: Span,
     pub abi: ExternAbi,
 }
+
+#[derive(Diagnostic)]
+#[diag(ast_passes_abi_x86_interrupt)]
+#[note]
+pub(crate) struct AbiX86Interrupt {
+    #[primary_span]
+    pub spans: Vec<Span>,
+    pub param_count: usize,
+}
diff --git a/compiler/rustc_ast_passes/src/feature_gate.rs b/compiler/rustc_ast_passes/src/feature_gate.rs
index c9344a76a7b..9ab5b0b3547 100644
--- a/compiler/rustc_ast_passes/src/feature_gate.rs
+++ b/compiler/rustc_ast_passes/src/feature_gate.rs
@@ -188,6 +188,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                         notable_trait => doc_notable_trait
                     }
                     "meant for internal use only" {
+                        attribute => rustdoc_internals
                         keyword => rustdoc_internals
                         fake_variadic => rustdoc_internals
                         search_unbox => rustdoc_internals
@@ -524,6 +525,7 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session, features: &Features) {
     gate_all!(where_clause_attrs, "attributes in `where` clause are unstable");
     gate_all!(super_let, "`super let` is experimental");
     gate_all!(frontmatter, "frontmatters are experimental");
+    gate_all!(coroutines, "coroutine syntax is experimental");
 
     if !visitor.features.never_patterns() {
         if let Some(spans) = spans.get(&sym::never_patterns) {
diff --git a/compiler/rustc_ast_pretty/Cargo.toml b/compiler/rustc_ast_pretty/Cargo.toml
index b704040be96..0c7e55305b4 100644
--- a/compiler/rustc_ast_pretty/Cargo.toml
+++ b/compiler/rustc_ast_pretty/Cargo.toml
@@ -5,7 +5,7 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-itertools = "0.12"
+itertools.workspace = true
 rustc_ast = { path = "../rustc_ast" }
 rustc_lexer = { path = "../rustc_lexer" }
 rustc_span = { path = "../rustc_span" }
@@ -13,5 +13,5 @@ rustc_span = { path = "../rustc_span" }
 
 [dev-dependencies]
 # tidy-alphabetical-start
-thin-vec = "0.2.12"
+thin-vec.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_ast_pretty/src/pprust/state.rs b/compiler/rustc_ast_pretty/src/pprust/state.rs
index 85f76036df7..a056ce3e29d 100644
--- a/compiler/rustc_ast_pretty/src/pprust/state.rs
+++ b/compiler/rustc_ast_pretty/src/pprust/state.rs
@@ -10,7 +10,7 @@ use std::borrow::Cow;
 use std::sync::Arc;
 
 use rustc_ast::attr::AttrIdGenerator;
-use rustc_ast::token::{self, CommentKind, Delimiter, IdentIsRaw, Token, TokenKind};
+use rustc_ast::token::{self, CommentKind, Delimiter, Token, TokenKind};
 use rustc_ast::tokenstream::{Spacing, TokenStream, TokenTree};
 use rustc_ast::util::classify;
 use rustc_ast::util::comments::{Comment, CommentStyle};
@@ -441,7 +441,7 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
     fn print_generic_args(&mut self, args: &ast::GenericArgs, colons_before_params: bool);
 
     fn print_ident(&mut self, ident: Ident) {
-        self.word(IdentPrinter::for_ast_ident(ident, ident.is_raw_guess()).to_string());
+        self.word(IdentPrinter::for_ast_ident(ident, ident.guess_print_mode()).to_string());
         self.ann_post(ident)
     }
 
@@ -1015,17 +1015,16 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
 
             /* Name components */
             token::Ident(name, is_raw) => {
-                IdentPrinter::new(name, is_raw.into(), convert_dollar_crate).to_string().into()
+                IdentPrinter::new(name, is_raw.to_print_mode_ident(), convert_dollar_crate)
+                    .to_string()
+                    .into()
             }
             token::NtIdent(ident, is_raw) => {
-                IdentPrinter::for_ast_ident(ident, is_raw.into()).to_string().into()
+                IdentPrinter::for_ast_ident(ident, is_raw.to_print_mode_ident()).to_string().into()
             }
 
-            token::Lifetime(name, IdentIsRaw::No)
-            | token::NtLifetime(Ident { name, .. }, IdentIsRaw::No) => name.to_string().into(),
-            token::Lifetime(name, IdentIsRaw::Yes)
-            | token::NtLifetime(Ident { name, .. }, IdentIsRaw::Yes) => {
-                format!("'r#{}", &name.as_str()[1..]).into()
+            token::Lifetime(name, is_raw) | token::NtLifetime(Ident { name, .. }, is_raw) => {
+                IdentPrinter::new(name, is_raw.to_print_mode_lifetime(), None).to_string().into()
             }
 
             /* Other */
diff --git a/compiler/rustc_attr_parsing/Cargo.toml b/compiler/rustc_attr_parsing/Cargo.toml
index cec9d62e656..8bfde43fd33 100644
--- a/compiler/rustc_attr_parsing/Cargo.toml
+++ b/compiler/rustc_attr_parsing/Cargo.toml
@@ -14,7 +14,9 @@ rustc_fluent_macro = { path = "../rustc_fluent_macro" }
 rustc_hir = { path = "../rustc_hir" }
 rustc_lexer = { path = "../rustc_lexer" }
 rustc_macros = { path = "../rustc_macros" }
+rustc_parse = { path = "../rustc_parse" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
-thin-vec = "0.2.12"
+rustc_target = { path = "../rustc_target" }
+thin-vec.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_attr_parsing/messages.ftl b/compiler/rustc_attr_parsing/messages.ftl
index de22ea322c7..b8a748563d5 100644
--- a/compiler/rustc_attr_parsing/messages.ftl
+++ b/compiler/rustc_attr_parsing/messages.ftl
@@ -10,6 +10,14 @@ attr_parsing_empty_attribute =
     unused attribute
     .suggestion = remove this attribute
 
+attr_parsing_invalid_target = `#[{$name}]` attribute cannot be used on {$target}
+    .help = `#[{$name}]` can {$only}be applied to {$applied}
+    .suggestion = remove the attribute
+attr_parsing_invalid_target_lint = `#[{$name}]` attribute cannot be used on {$target}
+    .warn = {-attr_parsing_previously_accepted}
+    .help = `#[{$name}]` can {$only}be applied to {$applied}
+    .suggestion = remove the attribute
+
 attr_parsing_empty_confusables =
     expected at least one confusable name
 attr_parsing_expected_one_cfg_pattern =
@@ -78,6 +86,12 @@ attr_parsing_invalid_repr_hint_no_value =
 attr_parsing_invalid_since =
     'since' must be a Rust version number, such as "1.31.0"
 
+attr_parsing_invalid_style = {$is_used_as_inner ->
+        [false] crate-level attribute should be an inner attribute: add an exclamation mark: `#![{$name}]`
+        *[other] the `#![{$name}]` attribute can only be used at the crate root
+    }
+    .note = This attribute does not have an `!`, which means it is applied to this {$target}
+
 attr_parsing_link_ordinal_out_of_range = ordinal value in `link_ordinal` is too large: `{$ordinal}`
     .note = the value may not exceed `u16::MAX`
 
@@ -162,3 +176,74 @@ attr_parsing_unused_multiple =
 
 -attr_parsing_previously_accepted =
     this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+
+attr_parsing_meta_bad_delim = wrong meta list delimiters
+attr_parsing_meta_bad_delim_suggestion = the delimiters should be `(` and `)`
+
+attr_parsing_unsafe_attr_outside_unsafe = unsafe attribute used without unsafe
+    .label = usage of unsafe attribute
+attr_parsing_unsafe_attr_outside_unsafe_suggestion = wrap the attribute in `unsafe(...)`
+
+attr_parsing_invalid_attr_unsafe = `{$name}` is not an unsafe attribute
+    .label = this is not an unsafe attribute
+    .suggestion = remove the `unsafe(...)`
+    .note = extraneous unsafe is not allowed in attributes
+
+attr_parsing_invalid_meta_item = expected a literal (`1u8`, `1.0f32`, `"string"`, etc.) here, found {$descr}
+    .remove_neg_sugg = negative numbers are not literals, try removing the `-` sign
+    .quote_ident_sugg = surround the identifier with quotation marks to make it into a string literal
+
+attr_parsing_suffixed_literal_in_attribute = suffixed literals are not allowed in attributes
+    .help = instead of using a suffixed literal (`1u8`, `1.0f32`, etc.), use an unsuffixed version (`1`, `1.0`, etc.)
+
+attr_parsing_as_needed_compatibility =
+    linking modifier `as-needed` is only compatible with `dylib` and `framework` linking kinds
+
+attr_parsing_bundle_needs_static =
+    linking modifier `bundle` is only compatible with `static` linking kind
+
+attr_parsing_empty_link_name =
+    link name must not be empty
+    .label = empty link name
+
+attr_parsing_import_name_type_raw =
+    import name type can only be used with link kind `raw-dylib`
+
+attr_parsing_import_name_type_x86 =
+    import name type is only supported on x86
+
+attr_parsing_incompatible_wasm_link =
+    `wasm_import_module` is incompatible with other arguments in `#[link]` attributes
+
+attr_parsing_invalid_link_modifier =
+    invalid linking modifier syntax, expected '+' or '-' prefix before one of: bundle, verbatim, whole-archive, as-needed
+
+attr_parsing_link_arg_unstable =
+    link kind `link-arg` is unstable
+
+attr_parsing_link_cfg_unstable =
+    link cfg is unstable
+
+attr_parsing_link_framework_apple =
+    link kind `framework` is only supported on Apple targets
+
+attr_parsing_link_requires_name =
+    `#[link]` attribute requires a `name = "string"` argument
+    .label = missing `name` argument
+
+attr_parsing_multiple_modifiers =
+    multiple `{$modifier}` modifiers in a single `modifiers` argument
+
+attr_parsing_multiple_renamings =
+    multiple renamings were specified for library `{$lib_name}`
+attr_parsing_raw_dylib_no_nul =
+    link name must not contain NUL characters if link kind is `raw-dylib`
+
+attr_parsing_raw_dylib_elf_unstable =
+    link kind `raw-dylib` is unstable on ELF platforms
+
+attr_parsing_raw_dylib_only_windows =
+    link kind `raw-dylib` is only supported on Windows targets
+
+attr_parsing_whole_archive_needs_static =
+    linking modifier `whole-archive` is only compatible with `static` linking kind
diff --git a/compiler/rustc_attr_parsing/src/attributes/allow_unstable.rs b/compiler/rustc_attr_parsing/src/attributes/allow_unstable.rs
index b3393e93de8..088fa73d742 100644
--- a/compiler/rustc_attr_parsing/src/attributes/allow_unstable.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/allow_unstable.rs
@@ -1,12 +1,6 @@
 use std::iter;
 
-use rustc_feature::{AttributeTemplate, template};
-use rustc_hir::attrs::AttributeKind;
-use rustc_span::{Span, Symbol, sym};
-
-use super::{CombineAttributeParser, ConvertFn};
-use crate::context::{AcceptContext, Stage};
-use crate::parser::ArgParser;
+use super::prelude::*;
 use crate::session_diagnostics;
 
 pub(crate) struct AllowInternalUnstableParser;
@@ -15,6 +9,12 @@ impl<S: Stage> CombineAttributeParser<S> for AllowInternalUnstableParser {
     type Item = (Symbol, Span);
     const CONVERT: ConvertFn<Self::Item> =
         |items, span| AttributeKind::AllowInternalUnstable(items, span);
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::MacroDef),
+        Allow(Target::Fn),
+        Warn(Target::Field),
+        Warn(Target::Arm),
+    ]);
     const TEMPLATE: AttributeTemplate = template!(Word, List: &["feat1, feat2, ..."]);
 
     fn extend<'c>(
@@ -32,6 +32,11 @@ impl<S: Stage> CombineAttributeParser<S> for UnstableFeatureBoundParser {
     const PATH: &'static [rustc_span::Symbol] = &[sym::unstable_feature_bound];
     type Item = (Symbol, Span);
     const CONVERT: ConvertFn<Self::Item> = |items, _| AttributeKind::UnstableFeatureBound(items);
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Fn),
+        Allow(Target::Impl { of_trait: true }),
+        Allow(Target::Trait),
+    ]);
     const TEMPLATE: AttributeTemplate = template!(Word, List: &["feat1, feat2, ..."]);
 
     fn extend<'c>(
@@ -53,6 +58,13 @@ impl<S: Stage> CombineAttributeParser<S> for AllowConstFnUnstableParser {
     type Item = Symbol;
     const CONVERT: ConvertFn<Self::Item> =
         |items, first_span| AttributeKind::AllowConstFnUnstable(items, first_span);
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Fn),
+        Allow(Target::Method(MethodKind::Inherent)),
+        Allow(Target::Method(MethodKind::Trait { body: false })),
+        Allow(Target::Method(MethodKind::Trait { body: true })),
+        Allow(Target::Method(MethodKind::TraitImpl)),
+    ]);
     const TEMPLATE: AttributeTemplate = template!(Word, List: &["feat1, feat2, ..."]);
 
     fn extend<'c>(
diff --git a/compiler/rustc_attr_parsing/src/attributes/body.rs b/compiler/rustc_attr_parsing/src/attributes/body.rs
index ab9330216f6..a1492d76194 100644
--- a/compiler/rustc_attr_parsing/src/attributes/body.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/body.rs
@@ -1,15 +1,12 @@
 //! Attributes that can be found in function body.
 
-use rustc_hir::attrs::AttributeKind;
-use rustc_span::{Symbol, sym};
-
-use super::{NoArgsAttributeParser, OnDuplicate};
-use crate::context::Stage;
+use super::prelude::*;
 
 pub(crate) struct CoroutineParser;
 
 impl<S: Stage> NoArgsAttributeParser<S> for CoroutineParser {
     const PATH: &[Symbol] = &[sym::coroutine];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Closure)]);
     const CREATE: fn(rustc_span::Span) -> AttributeKind = |span| AttributeKind::Coroutine(span);
 }
diff --git a/compiler/rustc_attr_parsing/src/attributes/cfg.rs b/compiler/rustc_attr_parsing/src/attributes/cfg.rs
index 695ee666476..70855611079 100644
--- a/compiler/rustc_attr_parsing/src/attributes/cfg.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/cfg.rs
@@ -36,7 +36,7 @@ pub fn parse_cfg_attr<'c, S: Stage>(
     parse_cfg_entry(cx, single)
 }
 
-fn parse_cfg_entry<S: Stage>(
+pub(crate) fn parse_cfg_entry<S: Stage>(
     cx: &mut AcceptContext<'_, '_, S>,
     item: &MetaItemOrLitParser<'_>,
 ) -> Option<CfgEntry> {
diff --git a/compiler/rustc_attr_parsing/src/attributes/codegen_attrs.rs b/compiler/rustc_attr_parsing/src/attributes/codegen_attrs.rs
index a9f77195d1b..ffdacff7152 100644
--- a/compiler/rustc_attr_parsing/src/attributes/codegen_attrs.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/codegen_attrs.rs
@@ -1,14 +1,7 @@
-use rustc_feature::{AttributeTemplate, template};
-use rustc_hir::attrs::{AttributeKind, CoverageAttrKind, OptimizeAttr, UsedBy};
+use rustc_hir::attrs::{CoverageAttrKind, OptimizeAttr, SanitizerSet, UsedBy};
 use rustc_session::parse::feature_err;
-use rustc_span::{Span, Symbol, sym};
-
-use super::{
-    AcceptMapping, AttributeOrder, AttributeParser, CombineAttributeParser, ConvertFn,
-    NoArgsAttributeParser, OnDuplicate, SingleAttributeParser,
-};
-use crate::context::{AcceptContext, FinalizeContext, Stage};
-use crate::parser::ArgParser;
+
+use super::prelude::*;
 use crate::session_diagnostics::{NakedFunctionIncompatibleAttribute, NullOnExport};
 
 pub(crate) struct OptimizeParser;
@@ -17,6 +10,13 @@ impl<S: Stage> SingleAttributeParser<S> for OptimizeParser {
     const PATH: &[Symbol] = &[sym::optimize];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Fn),
+        Allow(Target::Closure),
+        Allow(Target::Method(MethodKind::Trait { body: true })),
+        Allow(Target::Method(MethodKind::TraitImpl)),
+        Allow(Target::Method(MethodKind::Inherent)),
+    ]);
     const TEMPLATE: AttributeTemplate = template!(List: &["size", "speed", "none"]);
 
     fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
@@ -35,7 +35,7 @@ impl<S: Stage> SingleAttributeParser<S> for OptimizeParser {
             Some(sym::speed) => OptimizeAttr::Speed,
             Some(sym::none) => OptimizeAttr::DoNotOptimize,
             _ => {
-                cx.expected_specific_argument(single.span(), vec!["size", "speed", "none"]);
+                cx.expected_specific_argument(single.span(), &[sym::size, sym::speed, sym::none]);
                 OptimizeAttr::Default
             }
         };
@@ -49,6 +49,15 @@ pub(crate) struct ColdParser;
 impl<S: Stage> NoArgsAttributeParser<S> for ColdParser {
     const PATH: &[Symbol] = &[sym::cold];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowListWarnRest(&[
+        Allow(Target::Fn),
+        Allow(Target::Method(MethodKind::Trait { body: true })),
+        Allow(Target::Method(MethodKind::TraitImpl)),
+        Allow(Target::Method(MethodKind::Trait { body: false })),
+        Allow(Target::Method(MethodKind::Inherent)),
+        Allow(Target::ForeignFn),
+        Allow(Target::Closure),
+    ]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::Cold;
 }
 
@@ -58,11 +67,22 @@ impl<S: Stage> SingleAttributeParser<S> for CoverageParser {
     const PATH: &[Symbol] = &[sym::coverage];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Fn),
+        Allow(Target::Closure),
+        Allow(Target::Method(MethodKind::Trait { body: true })),
+        Allow(Target::Method(MethodKind::TraitImpl)),
+        Allow(Target::Method(MethodKind::Inherent)),
+        Allow(Target::Impl { of_trait: true }),
+        Allow(Target::Impl { of_trait: false }),
+        Allow(Target::Mod),
+        Allow(Target::Crate),
+    ]);
     const TEMPLATE: AttributeTemplate = template!(OneOf: &[sym::off, sym::on]);
 
     fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
         let Some(args) = args.list() else {
-            cx.expected_specific_argument_and_list(cx.attr_span, vec!["on", "off"]);
+            cx.expected_specific_argument_and_list(cx.attr_span, &[sym::on, sym::off]);
             return None;
         };
 
@@ -71,7 +91,8 @@ impl<S: Stage> SingleAttributeParser<S> for CoverageParser {
             return None;
         };
 
-        let fail_incorrect_argument = |span| cx.expected_specific_argument(span, vec!["on", "off"]);
+        let fail_incorrect_argument =
+            |span| cx.expected_specific_argument(span, &[sym::on, sym::off]);
 
         let Some(arg) = arg.meta_item() else {
             fail_incorrect_argument(args.span);
@@ -97,6 +118,17 @@ impl<S: Stage> SingleAttributeParser<S> for ExportNameParser {
     const PATH: &[rustc_span::Symbol] = &[sym::export_name];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepInnermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Static),
+        Allow(Target::Fn),
+        Allow(Target::Method(MethodKind::Inherent)),
+        Allow(Target::Method(MethodKind::Trait { body: true })),
+        Allow(Target::Method(MethodKind::TraitImpl)),
+        Warn(Target::Field),
+        Warn(Target::Arm),
+        Warn(Target::MacroDef),
+        Warn(Target::MacroCall),
+    ]);
     const TEMPLATE: AttributeTemplate = template!(NameValueStr: "name");
 
     fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
@@ -138,6 +170,13 @@ impl<S: Stage> AttributeParser<S> for NakedParser {
                 this.span = Some(cx.attr_span);
             }
         })];
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Fn),
+        Allow(Target::Method(MethodKind::Inherent)),
+        Allow(Target::Method(MethodKind::Trait { body: true })),
+        Allow(Target::Method(MethodKind::TraitImpl)),
+        Warn(Target::MacroCall),
+    ]);
 
     fn finalize(self, cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
         // FIXME(jdonszelmann): upgrade this list to *parsed* attributes
@@ -230,6 +269,19 @@ pub(crate) struct TrackCallerParser;
 impl<S: Stage> NoArgsAttributeParser<S> for TrackCallerParser {
     const PATH: &[Symbol] = &[sym::track_caller];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Fn),
+        Allow(Target::Method(MethodKind::Inherent)),
+        Allow(Target::Method(MethodKind::Trait { body: true })),
+        Allow(Target::Method(MethodKind::TraitImpl)),
+        Allow(Target::Method(MethodKind::Trait { body: false })),
+        Allow(Target::ForeignFn),
+        Allow(Target::Closure),
+        Warn(Target::MacroDef),
+        Warn(Target::Arm),
+        Warn(Target::Field),
+        Warn(Target::MacroCall),
+    ]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::TrackCaller;
 }
 
@@ -237,6 +289,12 @@ pub(crate) struct NoMangleParser;
 impl<S: Stage> NoArgsAttributeParser<S> for NoMangleParser {
     const PATH: &[Symbol] = &[sym::no_mangle];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowListWarnRest(&[
+        Allow(Target::Fn),
+        Allow(Target::Static),
+        Allow(Target::Method(MethodKind::Inherent)),
+        Allow(Target::Method(MethodKind::TraitImpl)),
+    ]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::NoMangle;
 }
 
@@ -289,7 +347,7 @@ impl<S: Stage> AttributeParser<S> for UsedParser {
                             UsedBy::Linker
                         }
                         _ => {
-                            cx.expected_specific_argument(l.span(), vec!["compiler", "linker"]);
+                            cx.expected_specific_argument(l.span(), &[sym::compiler, sym::linker]);
                             return;
                         }
                     }
@@ -310,6 +368,8 @@ impl<S: Stage> AttributeParser<S> for UsedParser {
             }
         },
     )];
+    const ALLOWED_TARGETS: AllowedTargets =
+        AllowedTargets::AllowList(&[Allow(Target::Static), Warn(Target::MacroCall)]);
 
     fn finalize(self, _cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
         // Ratcheting behaviour, if both `linker` and `compiler` are specified, use `linker`
@@ -321,56 +381,207 @@ impl<S: Stage> AttributeParser<S> for UsedParser {
     }
 }
 
+fn parse_tf_attribute<'c, S: Stage>(
+    cx: &'c mut AcceptContext<'_, '_, S>,
+    args: &'c ArgParser<'_>,
+) -> impl IntoIterator<Item = (Symbol, Span)> + 'c {
+    let mut features = Vec::new();
+    let ArgParser::List(list) = args else {
+        cx.expected_list(cx.attr_span);
+        return features;
+    };
+    if list.is_empty() {
+        cx.warn_empty_attribute(cx.attr_span);
+        return features;
+    }
+    for item in list.mixed() {
+        let Some(name_value) = item.meta_item() else {
+            cx.expected_name_value(item.span(), Some(sym::enable));
+            return features;
+        };
+
+        // Validate name
+        let Some(name) = name_value.path().word_sym() else {
+            cx.expected_name_value(name_value.path().span(), Some(sym::enable));
+            return features;
+        };
+        if name != sym::enable {
+            cx.expected_name_value(name_value.path().span(), Some(sym::enable));
+            return features;
+        }
+
+        // Use value
+        let Some(name_value) = name_value.args().name_value() else {
+            cx.expected_name_value(item.span(), Some(sym::enable));
+            return features;
+        };
+        let Some(value_str) = name_value.value_as_str() else {
+            cx.expected_string_literal(name_value.value_span, Some(name_value.value_as_lit()));
+            return features;
+        };
+        for feature in value_str.as_str().split(",") {
+            features.push((Symbol::intern(feature), item.span()));
+        }
+    }
+    features
+}
+
 pub(crate) struct TargetFeatureParser;
 
 impl<S: Stage> CombineAttributeParser<S> for TargetFeatureParser {
     type Item = (Symbol, Span);
     const PATH: &[Symbol] = &[sym::target_feature];
-    const CONVERT: ConvertFn<Self::Item> = |items, span| AttributeKind::TargetFeature(items, span);
+    const CONVERT: ConvertFn<Self::Item> = |items, span| AttributeKind::TargetFeature {
+        features: items,
+        attr_span: span,
+        was_forced: false,
+    };
+    const TEMPLATE: AttributeTemplate = template!(List: &["enable = \"feat1, feat2\""]);
+
+    fn extend<'c>(
+        cx: &'c mut AcceptContext<'_, '_, S>,
+        args: &'c ArgParser<'_>,
+    ) -> impl IntoIterator<Item = Self::Item> + 'c {
+        parse_tf_attribute(cx, args)
+    }
+
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Fn),
+        Allow(Target::Method(MethodKind::Inherent)),
+        Allow(Target::Method(MethodKind::Trait { body: true })),
+        Allow(Target::Method(MethodKind::TraitImpl)),
+        Warn(Target::Statement),
+        Warn(Target::Field),
+        Warn(Target::Arm),
+        Warn(Target::MacroDef),
+        Warn(Target::MacroCall),
+    ]);
+}
+
+pub(crate) struct ForceTargetFeatureParser;
+
+impl<S: Stage> CombineAttributeParser<S> for ForceTargetFeatureParser {
+    type Item = (Symbol, Span);
+    const PATH: &[Symbol] = &[sym::force_target_feature];
+    const CONVERT: ConvertFn<Self::Item> = |items, span| AttributeKind::TargetFeature {
+        features: items,
+        attr_span: span,
+        was_forced: true,
+    };
     const TEMPLATE: AttributeTemplate = template!(List: &["enable = \"feat1, feat2\""]);
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Fn),
+        Allow(Target::Method(MethodKind::Inherent)),
+        Allow(Target::Method(MethodKind::Trait { body: true })),
+        Allow(Target::Method(MethodKind::TraitImpl)),
+    ]);
 
     fn extend<'c>(
         cx: &'c mut AcceptContext<'_, '_, S>,
         args: &'c ArgParser<'_>,
     ) -> impl IntoIterator<Item = Self::Item> + 'c {
-        let mut features = Vec::new();
-        let ArgParser::List(list) = args else {
+        parse_tf_attribute(cx, args)
+    }
+}
+
+pub(crate) struct SanitizeParser;
+
+impl<S: Stage> SingleAttributeParser<S> for SanitizeParser {
+    const PATH: &[Symbol] = &[sym::sanitize];
+
+    // FIXME: still checked in check_attrs.rs
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(ALL_TARGETS);
+
+    const TEMPLATE: AttributeTemplate = template!(List: &[
+        r#"address = "on|off""#,
+        r#"kernel_address = "on|off""#,
+        r#"cfi = "on|off""#,
+        r#"hwaddress = "on|off""#,
+        r#"kcfi = "on|off""#,
+        r#"memory = "on|off""#,
+        r#"memtag = "on|off""#,
+        r#"shadow_call_stack = "on|off""#,
+        r#"thread = "on|off""#
+    ]);
+
+    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
+        let Some(list) = args.list() else {
             cx.expected_list(cx.attr_span);
-            return features;
+            return None;
         };
-        if list.is_empty() {
-            cx.warn_empty_attribute(cx.attr_span);
-            return features;
-        }
+
+        let mut on_set = SanitizerSet::empty();
+        let mut off_set = SanitizerSet::empty();
+
         for item in list.mixed() {
-            let Some(name_value) = item.meta_item() else {
-                cx.expected_name_value(item.span(), Some(sym::enable));
-                return features;
+            let Some(item) = item.meta_item() else {
+                cx.expected_name_value(item.span(), None);
+                continue;
             };
 
-            // Validate name
-            let Some(name) = name_value.path().word_sym() else {
-                cx.expected_name_value(name_value.path().span(), Some(sym::enable));
-                return features;
+            let path = item.path().word_sym();
+            let Some(value) = item.args().name_value() else {
+                cx.expected_name_value(item.span(), path);
+                continue;
             };
-            if name != sym::enable {
-                cx.expected_name_value(name_value.path().span(), Some(sym::enable));
-                return features;
-            }
 
-            // Use value
-            let Some(name_value) = name_value.args().name_value() else {
-                cx.expected_name_value(item.span(), Some(sym::enable));
-                return features;
-            };
-            let Some(value_str) = name_value.value_as_str() else {
-                cx.expected_string_literal(name_value.value_span, Some(name_value.value_as_lit()));
-                return features;
+            let mut apply = |s: SanitizerSet| {
+                let is_on = match value.value_as_str() {
+                    Some(sym::on) => true,
+                    Some(sym::off) => false,
+                    Some(_) => {
+                        cx.expected_specific_argument_strings(
+                            value.value_span,
+                            &[sym::on, sym::off],
+                        );
+                        return;
+                    }
+                    None => {
+                        cx.expected_string_literal(value.value_span, Some(value.value_as_lit()));
+                        return;
+                    }
+                };
+
+                if is_on {
+                    on_set |= s;
+                } else {
+                    off_set |= s;
+                }
             };
-            for feature in value_str.as_str().split(",") {
-                features.push((Symbol::intern(feature), item.span()));
+
+            match path {
+                Some(sym::address) | Some(sym::kernel_address) => {
+                    apply(SanitizerSet::ADDRESS | SanitizerSet::KERNELADDRESS)
+                }
+                Some(sym::cfi) => apply(SanitizerSet::CFI),
+                Some(sym::kcfi) => apply(SanitizerSet::KCFI),
+                Some(sym::memory) => apply(SanitizerSet::MEMORY),
+                Some(sym::memtag) => apply(SanitizerSet::MEMTAG),
+                Some(sym::shadow_call_stack) => apply(SanitizerSet::SHADOWCALLSTACK),
+                Some(sym::thread) => apply(SanitizerSet::THREAD),
+                Some(sym::hwaddress) => apply(SanitizerSet::HWADDRESS),
+                _ => {
+                    cx.expected_specific_argument_strings(
+                        item.path().span(),
+                        &[
+                            sym::address,
+                            sym::cfi,
+                            sym::kcfi,
+                            sym::memory,
+                            sym::memtag,
+                            sym::shadow_call_stack,
+                            sym::thread,
+                            sym::hwaddress,
+                        ],
+                    );
+                    continue;
+                }
             }
         }
-        features
+
+        Some(AttributeKind::Sanitize { on_set, off_set, span: cx.attr_span })
     }
 }
diff --git a/compiler/rustc_attr_parsing/src/attributes/confusables.rs b/compiler/rustc_attr_parsing/src/attributes/confusables.rs
index edd22172ca2..97e78dfb136 100644
--- a/compiler/rustc_attr_parsing/src/attributes/confusables.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/confusables.rs
@@ -1,11 +1,5 @@
-use rustc_feature::template;
-use rustc_hir::attrs::AttributeKind;
-use rustc_span::{Span, Symbol, sym};
-use thin_vec::ThinVec;
-
-use super::{AcceptMapping, AttributeParser};
-use crate::context::{FinalizeContext, Stage};
-use crate::session_diagnostics;
+use super::prelude::*;
+use crate::session_diagnostics::EmptyConfusables;
 
 #[derive(Default)]
 pub(crate) struct ConfusablesParser {
@@ -24,7 +18,7 @@ impl<S: Stage> AttributeParser<S> for ConfusablesParser {
             };
 
             if list.is_empty() {
-                cx.emit_err(session_diagnostics::EmptyConfusables { span: cx.attr_span });
+                cx.emit_err(EmptyConfusables { span: cx.attr_span });
             }
 
             for param in list.mixed() {
@@ -41,6 +35,8 @@ impl<S: Stage> AttributeParser<S> for ConfusablesParser {
             this.first_span.get_or_insert(cx.attr_span);
         },
     )];
+    const ALLOWED_TARGETS: AllowedTargets =
+        AllowedTargets::AllowList(&[Allow(Target::Method(MethodKind::Inherent))]);
 
     fn finalize(self, _cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
         if self.confusables.is_empty() {
diff --git a/compiler/rustc_attr_parsing/src/attributes/crate_level.rs b/compiler/rustc_attr_parsing/src/attributes/crate_level.rs
new file mode 100644
index 00000000000..2fed09b85e8
--- /dev/null
+++ b/compiler/rustc_attr_parsing/src/attributes/crate_level.rs
@@ -0,0 +1,36 @@
+use rustc_feature::AttributeType;
+
+use super::prelude::*;
+
+pub(crate) struct CrateNameParser;
+
+impl<S: Stage> SingleAttributeParser<S> for CrateNameParser {
+    const PATH: &[Symbol] = &[sym::crate_name];
+    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
+    const TEMPLATE: AttributeTemplate = template!(NameValueStr: "name");
+    const TYPE: AttributeType = AttributeType::CrateLevel;
+
+    // FIXME: crate name is allowed on all targets and ignored,
+    //        even though it should only be valid on crates of course
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(ALL_TARGETS);
+
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
+        let ArgParser::NameValue(n) = args else {
+            cx.expected_name_value(cx.attr_span, None);
+            return None;
+        };
+
+        let Some(name) = n.value_as_str() else {
+            cx.expected_string_literal(n.value_span, Some(n.value_as_lit()));
+            return None;
+        };
+
+        Some(AttributeKind::CrateName {
+            name,
+            name_span: n.value_span,
+            attr_span: cx.attr_span,
+            style: cx.attr_style,
+        })
+    }
+}
diff --git a/compiler/rustc_attr_parsing/src/attributes/deprecation.rs b/compiler/rustc_attr_parsing/src/attributes/deprecation.rs
index e57ea8bbb5c..31c698228ef 100644
--- a/compiler/rustc_attr_parsing/src/attributes/deprecation.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/deprecation.rs
@@ -1,12 +1,10 @@
-use rustc_feature::{AttributeTemplate, template};
-use rustc_hir::attrs::{AttributeKind, DeprecatedSince, Deprecation};
-use rustc_span::{Span, Symbol, sym};
+use rustc_hir::attrs::{DeprecatedSince, Deprecation};
 
+use super::prelude::*;
 use super::util::parse_version;
-use super::{AttributeOrder, OnDuplicate, SingleAttributeParser};
-use crate::context::{AcceptContext, Stage};
-use crate::parser::ArgParser;
-use crate::session_diagnostics;
+use crate::session_diagnostics::{
+    DeprecatedItemSuggestion, InvalidSince, MissingNote, MissingSince,
+};
 
 pub(crate) struct DeprecationParser;
 
@@ -38,6 +36,32 @@ impl<S: Stage> SingleAttributeParser<S> for DeprecationParser {
     const PATH: &[Symbol] = &[sym::deprecated];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepInnermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowListWarnRest(&[
+        Allow(Target::Fn),
+        Allow(Target::Mod),
+        Allow(Target::Struct),
+        Allow(Target::Enum),
+        Allow(Target::Union),
+        Allow(Target::Const),
+        Allow(Target::Static),
+        Allow(Target::MacroDef),
+        Allow(Target::Method(MethodKind::Inherent)),
+        Allow(Target::Method(MethodKind::Trait { body: false })),
+        Allow(Target::Method(MethodKind::Trait { body: true })),
+        Allow(Target::TyAlias),
+        Allow(Target::Use),
+        Allow(Target::ForeignFn),
+        Allow(Target::ForeignStatic),
+        Allow(Target::ForeignTy),
+        Allow(Target::Field),
+        Allow(Target::Trait),
+        Allow(Target::AssocTy),
+        Allow(Target::AssocConst),
+        Allow(Target::Variant),
+        Allow(Target::Impl { of_trait: false }), //FIXME This does not make sense
+        Allow(Target::Crate),
+        Error(Target::WherePredicate),
+    ]);
     const TEMPLATE: AttributeTemplate = template!(
         Word,
         List: &[r#"since = "version""#, r#"note = "reason""#, r#"since = "version", note = "reason""#],
@@ -75,7 +99,7 @@ impl<S: Stage> SingleAttributeParser<S> for DeprecationParser {
                         }
                         Some(name @ sym::suggestion) => {
                             if !features.deprecated_suggestion() {
-                                cx.emit_err(session_diagnostics::DeprecatedItemSuggestion {
+                                cx.emit_err(DeprecatedItemSuggestion {
                                     span: param.span(),
                                     is_nightly: cx.sess().is_nightly_build(),
                                     details: (),
@@ -117,18 +141,18 @@ impl<S: Stage> SingleAttributeParser<S> for DeprecationParser {
             } else if let Some(version) = parse_version(since) {
                 DeprecatedSince::RustcVersion(version)
             } else {
-                cx.emit_err(session_diagnostics::InvalidSince { span: cx.attr_span });
+                cx.emit_err(InvalidSince { span: cx.attr_span });
                 DeprecatedSince::Err
             }
         } else if is_rustc {
-            cx.emit_err(session_diagnostics::MissingSince { span: cx.attr_span });
+            cx.emit_err(MissingSince { span: cx.attr_span });
             DeprecatedSince::Err
         } else {
             DeprecatedSince::Unspecified
         };
 
         if is_rustc && note.is_none() {
-            cx.emit_err(session_diagnostics::MissingNote { span: cx.attr_span });
+            cx.emit_err(MissingNote { span: cx.attr_span });
             return None;
         }
 
diff --git a/compiler/rustc_attr_parsing/src/attributes/dummy.rs b/compiler/rustc_attr_parsing/src/attributes/dummy.rs
index bbcd9ab530c..7293cee842c 100644
--- a/compiler/rustc_attr_parsing/src/attributes/dummy.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/dummy.rs
@@ -5,12 +5,14 @@ use rustc_span::{Symbol, sym};
 use crate::attributes::{AttributeOrder, OnDuplicate, SingleAttributeParser};
 use crate::context::{AcceptContext, Stage};
 use crate::parser::ArgParser;
+use crate::target_checking::{ALL_TARGETS, AllowedTargets};
 
 pub(crate) struct DummyParser;
 impl<S: Stage> SingleAttributeParser<S> for DummyParser {
     const PATH: &[Symbol] = &[sym::rustc_dummy];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepInnermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Ignore;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(ALL_TARGETS);
     const TEMPLATE: AttributeTemplate = template!(Word); // Anything, really
 
     fn convert(_: &mut AcceptContext<'_, '_, S>, _: &ArgParser<'_>) -> Option<AttributeKind> {
diff --git a/compiler/rustc_attr_parsing/src/attributes/inline.rs b/compiler/rustc_attr_parsing/src/attributes/inline.rs
index e9a45f20bff..a73430c9d00 100644
--- a/compiler/rustc_attr_parsing/src/attributes/inline.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/inline.rs
@@ -2,15 +2,9 @@
 //                      note: need to model better how duplicate attr errors work when not using
 //                      SingleAttributeParser which is what we have two of here.
 
-use rustc_feature::{AttributeTemplate, template};
 use rustc_hir::attrs::{AttributeKind, InlineAttr};
-use rustc_hir::lints::AttributeLintKind;
-use rustc_span::{Symbol, sym};
 
-use super::{AcceptContext, AttributeOrder, OnDuplicate};
-use crate::attributes::SingleAttributeParser;
-use crate::context::Stage;
-use crate::parser::ArgParser;
+use super::prelude::*;
 
 pub(crate) struct InlineParser;
 
@@ -18,6 +12,21 @@ impl<S: Stage> SingleAttributeParser<S> for InlineParser {
     const PATH: &'static [Symbol] = &[sym::inline];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Fn),
+        Allow(Target::Method(MethodKind::Inherent)),
+        Allow(Target::Method(MethodKind::Trait { body: true })),
+        Allow(Target::Method(MethodKind::TraitImpl)),
+        Allow(Target::Closure),
+        Allow(Target::Delegation { mac: false }),
+        Warn(Target::Method(MethodKind::Trait { body: false })),
+        Warn(Target::ForeignFn),
+        Warn(Target::Field),
+        Warn(Target::MacroDef),
+        Warn(Target::Arm),
+        Warn(Target::AssocConst),
+        Warn(Target::MacroCall),
+    ]);
     const TEMPLATE: AttributeTemplate = template!(
         Word,
         List: &["always", "never"],
@@ -41,14 +50,14 @@ impl<S: Stage> SingleAttributeParser<S> for InlineParser {
                         Some(AttributeKind::Inline(InlineAttr::Never, cx.attr_span))
                     }
                     _ => {
-                        cx.expected_specific_argument(l.span(), vec!["always", "never"]);
+                        cx.expected_specific_argument(l.span(), &[sym::always, sym::never]);
                         return None;
                     }
                 }
             }
             ArgParser::NameValue(_) => {
-                let suggestions =
-                    <Self as SingleAttributeParser<S>>::TEMPLATE.suggestions(false, "inline");
+                let suggestions = <Self as SingleAttributeParser<S>>::TEMPLATE
+                    .suggestions(cx.attr_style, "inline");
                 let span = cx.attr_span;
                 cx.emit_lint(AttributeLintKind::IllFormedAttributeInput { suggestions }, span);
                 return None;
@@ -63,6 +72,7 @@ impl<S: Stage> SingleAttributeParser<S> for RustcForceInlineParser {
     const PATH: &'static [Symbol] = &[sym::rustc_force_inline];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Fn)]);
     const TEMPLATE: AttributeTemplate = template!(Word, List: &["reason"], NameValueStr: "reason");
 
     fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
diff --git a/compiler/rustc_attr_parsing/src/attributes/link_attrs.rs b/compiler/rustc_attr_parsing/src/attributes/link_attrs.rs
index d406c30b83e..d4942e56f42 100644
--- a/compiler/rustc_attr_parsing/src/attributes/link_attrs.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/link_attrs.rs
@@ -1,14 +1,21 @@
-use rustc_feature::{AttributeTemplate, template};
-use rustc_hir::attrs::AttributeKind;
+use rustc_feature::Features;
 use rustc_hir::attrs::AttributeKind::{LinkName, LinkOrdinal, LinkSection};
-use rustc_span::{Span, Symbol, sym};
+use rustc_hir::attrs::*;
+use rustc_session::Session;
+use rustc_session::parse::feature_err;
+use rustc_span::kw;
+use rustc_target::spec::BinaryFormat;
 
-use crate::attributes::{
-    AttributeOrder, NoArgsAttributeParser, OnDuplicate, SingleAttributeParser,
+use super::prelude::*;
+use super::util::parse_single_integer;
+use crate::attributes::cfg::parse_cfg_entry;
+use crate::fluent_generated;
+use crate::session_diagnostics::{
+    AsNeededCompatibility, BundleNeedsStatic, EmptyLinkName, ImportNameTypeRaw, ImportNameTypeX86,
+    IncompatibleWasmLink, InvalidLinkModifier, LinkFrameworkApple, LinkOrdinalOutOfRange,
+    LinkRequiresName, MultipleModifiers, NullOnLinkSection, RawDylibNoNul, RawDylibOnlyWindows,
+    WholeArchiveNeedsStatic,
 };
-use crate::context::{AcceptContext, Stage, parse_single_integer};
-use crate::parser::ArgParser;
-use crate::session_diagnostics::{LinkOrdinalOutOfRange, NullOnLinkSection};
 
 pub(crate) struct LinkNameParser;
 
@@ -16,6 +23,10 @@ impl<S: Stage> SingleAttributeParser<S> for LinkNameParser {
     const PATH: &[Symbol] = &[sym::link_name];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepInnermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowListWarnRest(&[
+        Allow(Target::ForeignFn),
+        Allow(Target::ForeignStatic),
+    ]);
     const TEMPLATE: AttributeTemplate = template!(
         NameValueStr: "name",
         "https://doc.rust-lang.org/reference/items/external-blocks.html#the-link_name-attribute"
@@ -35,12 +46,417 @@ impl<S: Stage> SingleAttributeParser<S> for LinkNameParser {
     }
 }
 
+pub(crate) struct LinkParser;
+
+impl<S: Stage> CombineAttributeParser<S> for LinkParser {
+    type Item = LinkEntry;
+    const PATH: &[Symbol] = &[sym::link];
+    const CONVERT: ConvertFn<Self::Item> = AttributeKind::Link;
+    const TEMPLATE: AttributeTemplate = template!(List: &[
+            r#"name = "...""#,
+            r#"name = "...", kind = "dylib|static|...""#,
+            r#"name = "...", wasm_import_module = "...""#,
+            r#"name = "...", import_name_type = "decorated|noprefix|undecorated""#,
+            r#"name = "...", kind = "dylib|static|...", wasm_import_module = "...", import_name_type = "decorated|noprefix|undecorated""#,
+        ], "https://doc.rust-lang.org/reference/items/external-blocks.html#the-link-attribute");
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(ALL_TARGETS); //FIXME Still checked fully in `check_attr.rs`
+
+    fn extend<'c>(
+        cx: &'c mut AcceptContext<'_, '_, S>,
+        args: &'c ArgParser<'_>,
+    ) -> impl IntoIterator<Item = Self::Item> + 'c {
+        let mut result = None;
+        let Some(items) = args.list() else {
+            cx.expected_list(cx.attr_span);
+            return result;
+        };
+
+        let sess = cx.sess();
+        let features = cx.features();
+
+        let mut name = None;
+        let mut kind = None;
+        let mut modifiers = None;
+        let mut cfg = None;
+        let mut wasm_import_module = None;
+        let mut import_name_type = None;
+        for item in items.mixed() {
+            let Some(item) = item.meta_item() else {
+                cx.unexpected_literal(item.span());
+                continue;
+            };
+
+            let cont = match item.path().word().map(|ident| ident.name) {
+                Some(sym::name) => Self::parse_link_name(item, &mut name, cx),
+                Some(sym::kind) => Self::parse_link_kind(item, &mut kind, cx, sess, features),
+                Some(sym::modifiers) => Self::parse_link_modifiers(item, &mut modifiers, cx),
+                Some(sym::cfg) => Self::parse_link_cfg(item, &mut cfg, cx, sess, features),
+                Some(sym::wasm_import_module) => {
+                    Self::parse_link_wasm_import_module(item, &mut wasm_import_module, cx)
+                }
+                Some(sym::import_name_type) => {
+                    Self::parse_link_import_name_type(item, &mut import_name_type, cx)
+                }
+                _ => {
+                    cx.expected_specific_argument_strings(
+                        item.span(),
+                        &[
+                            sym::name,
+                            sym::kind,
+                            sym::modifiers,
+                            sym::cfg,
+                            sym::wasm_import_module,
+                            sym::import_name_type,
+                        ],
+                    );
+                    true
+                }
+            };
+            if !cont {
+                return result;
+            }
+        }
+
+        // Do this outside the above loop so we don't depend on modifiers coming after kinds
+        let mut verbatim = None;
+        if let Some((modifiers, span)) = modifiers {
+            for modifier in modifiers.as_str().split(',') {
+                let (modifier, value): (Symbol, bool) = match modifier.strip_prefix(&['+', '-']) {
+                    Some(m) => (Symbol::intern(m), modifier.starts_with('+')),
+                    None => {
+                        cx.emit_err(InvalidLinkModifier { span });
+                        continue;
+                    }
+                };
+
+                macro report_unstable_modifier($feature: ident) {
+                    if !features.$feature() {
+                        // FIXME: make this translatable
+                        #[expect(rustc::untranslatable_diagnostic)]
+                        feature_err(
+                            sess,
+                            sym::$feature,
+                            span,
+                            format!("linking modifier `{modifier}` is unstable"),
+                        )
+                        .emit();
+                    }
+                }
+                let assign_modifier = |dst: &mut Option<bool>| {
+                    if dst.is_some() {
+                        cx.emit_err(MultipleModifiers { span, modifier });
+                    } else {
+                        *dst = Some(value);
+                    }
+                };
+                match (modifier, &mut kind) {
+                    (sym::bundle, Some(NativeLibKind::Static { bundle, .. })) => {
+                        assign_modifier(bundle)
+                    }
+                    (sym::bundle, _) => {
+                        cx.emit_err(BundleNeedsStatic { span });
+                    }
+
+                    (sym::verbatim, _) => assign_modifier(&mut verbatim),
+
+                    (
+                        sym::whole_dash_archive,
+                        Some(NativeLibKind::Static { whole_archive, .. }),
+                    ) => assign_modifier(whole_archive),
+                    (sym::whole_dash_archive, _) => {
+                        cx.emit_err(WholeArchiveNeedsStatic { span });
+                    }
+
+                    (sym::as_dash_needed, Some(NativeLibKind::Dylib { as_needed }))
+                    | (sym::as_dash_needed, Some(NativeLibKind::Framework { as_needed })) => {
+                        report_unstable_modifier!(native_link_modifiers_as_needed);
+                        assign_modifier(as_needed)
+                    }
+                    (sym::as_dash_needed, _) => {
+                        cx.emit_err(AsNeededCompatibility { span });
+                    }
+
+                    _ => {
+                        cx.expected_specific_argument_strings(
+                            span,
+                            &[
+                                sym::bundle,
+                                sym::verbatim,
+                                sym::whole_dash_archive,
+                                sym::as_dash_needed,
+                            ],
+                        );
+                    }
+                }
+            }
+        }
+
+        if let Some((_, span)) = wasm_import_module {
+            if name.is_some() || kind.is_some() || modifiers.is_some() || cfg.is_some() {
+                cx.emit_err(IncompatibleWasmLink { span });
+            }
+        }
+
+        if wasm_import_module.is_some() {
+            (name, kind) = (wasm_import_module, Some(NativeLibKind::WasmImportModule));
+        }
+        let Some((name, name_span)) = name else {
+            cx.emit_err(LinkRequiresName { span: cx.attr_span });
+            return result;
+        };
+
+        // Do this outside of the loop so that `import_name_type` can be specified before `kind`.
+        if let Some((_, span)) = import_name_type {
+            if kind != Some(NativeLibKind::RawDylib) {
+                cx.emit_err(ImportNameTypeRaw { span });
+            }
+        }
+
+        if let Some(NativeLibKind::RawDylib) = kind
+            && name.as_str().contains('\0')
+        {
+            cx.emit_err(RawDylibNoNul { span: name_span });
+        }
+
+        result = Some(LinkEntry {
+            span: cx.attr_span,
+            kind: kind.unwrap_or(NativeLibKind::Unspecified),
+            name,
+            cfg,
+            verbatim,
+            import_name_type,
+        });
+        result
+    }
+}
+
+impl LinkParser {
+    fn parse_link_name<S: Stage>(
+        item: &MetaItemParser<'_>,
+        name: &mut Option<(Symbol, Span)>,
+        cx: &mut AcceptContext<'_, '_, S>,
+    ) -> bool {
+        if name.is_some() {
+            cx.duplicate_key(item.span(), sym::name);
+            return true;
+        }
+        let Some(nv) = item.args().name_value() else {
+            cx.expected_name_value(item.span(), Some(sym::name));
+            return false;
+        };
+        let Some(link_name) = nv.value_as_str() else {
+            cx.expected_name_value(item.span(), Some(sym::name));
+            return false;
+        };
+
+        if link_name.is_empty() {
+            cx.emit_err(EmptyLinkName { span: nv.value_span });
+        }
+        *name = Some((link_name, nv.value_span));
+        true
+    }
+
+    fn parse_link_kind<S: Stage>(
+        item: &MetaItemParser<'_>,
+        kind: &mut Option<NativeLibKind>,
+        cx: &mut AcceptContext<'_, '_, S>,
+        sess: &Session,
+        features: &Features,
+    ) -> bool {
+        if kind.is_some() {
+            cx.duplicate_key(item.span(), sym::kind);
+            return true;
+        }
+        let Some(nv) = item.args().name_value() else {
+            cx.expected_name_value(item.span(), Some(sym::kind));
+            return true;
+        };
+        let Some(link_kind) = nv.value_as_str() else {
+            cx.expected_name_value(item.span(), Some(sym::kind));
+            return true;
+        };
+
+        let link_kind = match link_kind {
+            kw::Static => NativeLibKind::Static { bundle: None, whole_archive: None },
+            sym::dylib => NativeLibKind::Dylib { as_needed: None },
+            sym::framework => {
+                if !sess.target.is_like_darwin {
+                    cx.emit_err(LinkFrameworkApple { span: nv.value_span });
+                }
+                NativeLibKind::Framework { as_needed: None }
+            }
+            sym::raw_dash_dylib => {
+                if sess.target.is_like_windows {
+                    // raw-dylib is stable and working on Windows
+                } else if sess.target.binary_format == BinaryFormat::Elf && features.raw_dylib_elf()
+                {
+                    // raw-dylib is unstable on ELF, but the user opted in
+                } else if sess.target.binary_format == BinaryFormat::Elf && sess.is_nightly_build()
+                {
+                    feature_err(
+                        sess,
+                        sym::raw_dylib_elf,
+                        nv.value_span,
+                        fluent_generated::attr_parsing_raw_dylib_elf_unstable,
+                    )
+                    .emit();
+                } else {
+                    cx.emit_err(RawDylibOnlyWindows { span: nv.value_span });
+                }
+
+                NativeLibKind::RawDylib
+            }
+            sym::link_dash_arg => {
+                if !features.link_arg_attribute() {
+                    feature_err(
+                        sess,
+                        sym::link_arg_attribute,
+                        nv.value_span,
+                        fluent_generated::attr_parsing_link_arg_unstable,
+                    )
+                    .emit();
+                }
+                NativeLibKind::LinkArg
+            }
+            _kind => {
+                cx.expected_specific_argument_strings(
+                    nv.value_span,
+                    &[
+                        kw::Static,
+                        sym::dylib,
+                        sym::framework,
+                        sym::raw_dash_dylib,
+                        sym::link_dash_arg,
+                    ],
+                );
+                return true;
+            }
+        };
+        *kind = Some(link_kind);
+        true
+    }
+
+    fn parse_link_modifiers<S: Stage>(
+        item: &MetaItemParser<'_>,
+        modifiers: &mut Option<(Symbol, Span)>,
+        cx: &mut AcceptContext<'_, '_, S>,
+    ) -> bool {
+        if modifiers.is_some() {
+            cx.duplicate_key(item.span(), sym::modifiers);
+            return true;
+        }
+        let Some(nv) = item.args().name_value() else {
+            cx.expected_name_value(item.span(), Some(sym::modifiers));
+            return true;
+        };
+        let Some(link_modifiers) = nv.value_as_str() else {
+            cx.expected_name_value(item.span(), Some(sym::modifiers));
+            return true;
+        };
+        *modifiers = Some((link_modifiers, nv.value_span));
+        true
+    }
+
+    fn parse_link_cfg<S: Stage>(
+        item: &MetaItemParser<'_>,
+        cfg: &mut Option<CfgEntry>,
+        cx: &mut AcceptContext<'_, '_, S>,
+        sess: &Session,
+        features: &Features,
+    ) -> bool {
+        if cfg.is_some() {
+            cx.duplicate_key(item.span(), sym::cfg);
+            return true;
+        }
+        let Some(link_cfg) = item.args().list() else {
+            cx.expected_list(item.span());
+            return true;
+        };
+        let Some(link_cfg) = link_cfg.single() else {
+            cx.expected_single_argument(item.span());
+            return true;
+        };
+        if !features.link_cfg() {
+            feature_err(
+                sess,
+                sym::link_cfg,
+                item.span(),
+                fluent_generated::attr_parsing_link_cfg_unstable,
+            )
+            .emit();
+        }
+        *cfg = parse_cfg_entry(cx, link_cfg);
+        true
+    }
+
+    fn parse_link_wasm_import_module<S: Stage>(
+        item: &MetaItemParser<'_>,
+        wasm_import_module: &mut Option<(Symbol, Span)>,
+        cx: &mut AcceptContext<'_, '_, S>,
+    ) -> bool {
+        if wasm_import_module.is_some() {
+            cx.duplicate_key(item.span(), sym::wasm_import_module);
+            return true;
+        }
+        let Some(nv) = item.args().name_value() else {
+            cx.expected_name_value(item.span(), Some(sym::wasm_import_module));
+            return true;
+        };
+        let Some(link_wasm_import_module) = nv.value_as_str() else {
+            cx.expected_name_value(item.span(), Some(sym::wasm_import_module));
+            return true;
+        };
+        *wasm_import_module = Some((link_wasm_import_module, item.span()));
+        true
+    }
+
+    fn parse_link_import_name_type<S: Stage>(
+        item: &MetaItemParser<'_>,
+        import_name_type: &mut Option<(PeImportNameType, Span)>,
+        cx: &mut AcceptContext<'_, '_, S>,
+    ) -> bool {
+        if import_name_type.is_some() {
+            cx.duplicate_key(item.span(), sym::import_name_type);
+            return true;
+        }
+        let Some(nv) = item.args().name_value() else {
+            cx.expected_name_value(item.span(), Some(sym::import_name_type));
+            return true;
+        };
+        let Some(link_import_name_type) = nv.value_as_str() else {
+            cx.expected_name_value(item.span(), Some(sym::import_name_type));
+            return true;
+        };
+        if cx.sess().target.arch != "x86" {
+            cx.emit_err(ImportNameTypeX86 { span: item.span() });
+            return true;
+        }
+
+        let link_import_name_type = match link_import_name_type {
+            sym::decorated => PeImportNameType::Decorated,
+            sym::noprefix => PeImportNameType::NoPrefix,
+            sym::undecorated => PeImportNameType::Undecorated,
+            _ => {
+                cx.expected_specific_argument_strings(
+                    item.span(),
+                    &[sym::decorated, sym::noprefix, sym::undecorated],
+                );
+                return true;
+            }
+        };
+        *import_name_type = Some((link_import_name_type, item.span()));
+        true
+    }
+}
+
 pub(crate) struct LinkSectionParser;
 
 impl<S: Stage> SingleAttributeParser<S> for LinkSectionParser {
     const PATH: &[Symbol] = &[sym::link_section];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepInnermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
+    const ALLOWED_TARGETS: AllowedTargets =
+        AllowedTargets::AllowListWarnRest(&[Allow(Target::Static), Allow(Target::Fn)]);
     const TEMPLATE: AttributeTemplate = template!(
         NameValueStr: "name",
         "https://doc.rust-lang.org/reference/abi.html#the-link_section-attribute"
@@ -70,6 +486,7 @@ pub(crate) struct ExportStableParser;
 impl<S: Stage> NoArgsAttributeParser<S> for ExportStableParser {
     const PATH: &[Symbol] = &[sym::export_stable];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(ALL_TARGETS); //FIXME Still checked fully in `check_attr.rs`
     const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::ExportStable;
 }
 
@@ -77,6 +494,7 @@ pub(crate) struct FfiConstParser;
 impl<S: Stage> NoArgsAttributeParser<S> for FfiConstParser {
     const PATH: &[Symbol] = &[sym::ffi_const];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::ForeignFn)]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::FfiConst;
 }
 
@@ -84,6 +502,7 @@ pub(crate) struct FfiPureParser;
 impl<S: Stage> NoArgsAttributeParser<S> for FfiPureParser {
     const PATH: &[Symbol] = &[sym::ffi_pure];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::ForeignFn)]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::FfiPure;
 }
 
@@ -91,6 +510,12 @@ pub(crate) struct StdInternalSymbolParser;
 impl<S: Stage> NoArgsAttributeParser<S> for StdInternalSymbolParser {
     const PATH: &[Symbol] = &[sym::rustc_std_internal_symbol];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Fn),
+        Allow(Target::ForeignFn),
+        Allow(Target::Static),
+        Allow(Target::ForeignStatic),
+    ]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::StdInternalSymbol;
 }
 
@@ -100,6 +525,11 @@ impl<S: Stage> SingleAttributeParser<S> for LinkOrdinalParser {
     const PATH: &[Symbol] = &[sym::link_ordinal];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::ForeignFn),
+        Allow(Target::ForeignStatic),
+        Warn(Target::MacroCall),
+    ]);
     const TEMPLATE: AttributeTemplate = template!(
         List: &["ordinal"],
         "https://doc.rust-lang.org/reference/items/external-blocks.html#the-link_ordinal-attribute"
@@ -129,3 +559,87 @@ impl<S: Stage> SingleAttributeParser<S> for LinkOrdinalParser {
         Some(LinkOrdinal { ordinal, span: cx.attr_span })
     }
 }
+
+pub(crate) struct LinkageParser;
+
+impl<S: Stage> SingleAttributeParser<S> for LinkageParser {
+    const PATH: &[Symbol] = &[sym::linkage];
+
+    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
+
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Fn),
+        Allow(Target::Method(MethodKind::Inherent)),
+        Allow(Target::Method(MethodKind::Trait { body: false })),
+        Allow(Target::Method(MethodKind::Trait { body: true })),
+        Allow(Target::Method(MethodKind::TraitImpl)),
+        Allow(Target::Static),
+        Allow(Target::ForeignStatic),
+        Allow(Target::ForeignFn),
+    ]);
+
+    const TEMPLATE: AttributeTemplate = template!(NameValueStr: [
+        "available_externally",
+        "common",
+        "extern_weak",
+        "external",
+        "internal",
+        "linkonce",
+        "linkonce_odr",
+        "weak",
+        "weak_odr",
+    ]);
+
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
+        let Some(name_value) = args.name_value() else {
+            cx.expected_name_value(cx.attr_span, Some(sym::linkage));
+            return None;
+        };
+
+        let Some(value) = name_value.value_as_str() else {
+            cx.expected_string_literal(name_value.value_span, Some(name_value.value_as_lit()));
+            return None;
+        };
+
+        // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
+        // applicable to variable declarations and may not really make sense for
+        // Rust code in the first place but allow them anyway and trust that the
+        // user knows what they're doing. Who knows, unanticipated use cases may pop
+        // up in the future.
+        //
+        // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
+        // and don't have to be, LLVM treats them as no-ops.
+        let linkage = match value {
+            sym::available_externally => Linkage::AvailableExternally,
+            sym::common => Linkage::Common,
+            sym::extern_weak => Linkage::ExternalWeak,
+            sym::external => Linkage::External,
+            sym::internal => Linkage::Internal,
+            sym::linkonce => Linkage::LinkOnceAny,
+            sym::linkonce_odr => Linkage::LinkOnceODR,
+            sym::weak => Linkage::WeakAny,
+            sym::weak_odr => Linkage::WeakODR,
+
+            _ => {
+                cx.expected_specific_argument(
+                    name_value.value_span,
+                    &[
+                        sym::available_externally,
+                        sym::common,
+                        sym::extern_weak,
+                        sym::external,
+                        sym::internal,
+                        sym::linkonce,
+                        sym::linkonce_odr,
+                        sym::weak,
+                        sym::weak_odr,
+                    ],
+                );
+                return None;
+            }
+        };
+
+        Some(AttributeKind::Linkage(linkage, cx.attr_span))
+    }
+}
diff --git a/compiler/rustc_attr_parsing/src/attributes/lint_helpers.rs b/compiler/rustc_attr_parsing/src/attributes/lint_helpers.rs
index 9530fec07d6..63b0809d0d8 100644
--- a/compiler/rustc_attr_parsing/src/attributes/lint_helpers.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/lint_helpers.rs
@@ -1,13 +1,16 @@
-use rustc_hir::attrs::AttributeKind;
-use rustc_span::{Span, Symbol, sym};
-
-use crate::attributes::{NoArgsAttributeParser, OnDuplicate};
-use crate::context::Stage;
+use super::prelude::*;
 
 pub(crate) struct AsPtrParser;
 impl<S: Stage> NoArgsAttributeParser<S> for AsPtrParser {
     const PATH: &[Symbol] = &[sym::rustc_as_ptr];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Fn),
+        Allow(Target::Method(MethodKind::Inherent)),
+        Allow(Target::Method(MethodKind::Trait { body: false })),
+        Allow(Target::Method(MethodKind::Trait { body: true })),
+        Allow(Target::Method(MethodKind::TraitImpl)),
+    ]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::AsPtr;
 }
 
@@ -15,6 +18,11 @@ pub(crate) struct PubTransparentParser;
 impl<S: Stage> NoArgsAttributeParser<S> for PubTransparentParser {
     const PATH: &[Symbol] = &[sym::rustc_pub_transparent];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Struct),
+        Allow(Target::Enum),
+        Allow(Target::Union),
+    ]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::PubTransparent;
 }
 
@@ -22,6 +30,11 @@ pub(crate) struct PassByValueParser;
 impl<S: Stage> NoArgsAttributeParser<S> for PassByValueParser {
     const PATH: &[Symbol] = &[sym::rustc_pass_by_value];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Struct),
+        Allow(Target::Enum),
+        Allow(Target::TyAlias),
+    ]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::PassByValue;
 }
 
@@ -29,5 +42,10 @@ pub(crate) struct AutomaticallyDerivedParser;
 impl<S: Stage> NoArgsAttributeParser<S> for AutomaticallyDerivedParser {
     const PATH: &[Symbol] = &[sym::automatically_derived];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowListWarnRest(&[
+        Allow(Target::Impl { of_trait: true }),
+        Error(Target::Crate),
+        Error(Target::WherePredicate),
+    ]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::AutomaticallyDerived;
 }
diff --git a/compiler/rustc_attr_parsing/src/attributes/loop_match.rs b/compiler/rustc_attr_parsing/src/attributes/loop_match.rs
index 868c113a6d1..528090b8673 100644
--- a/compiler/rustc_attr_parsing/src/attributes/loop_match.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/loop_match.rs
@@ -1,13 +1,10 @@
-use rustc_hir::attrs::AttributeKind;
-use rustc_span::{Span, Symbol, sym};
-
-use crate::attributes::{NoArgsAttributeParser, OnDuplicate};
-use crate::context::Stage;
+use super::prelude::*;
 
 pub(crate) struct LoopMatchParser;
 impl<S: Stage> NoArgsAttributeParser<S> for LoopMatchParser {
     const PATH: &[Symbol] = &[sym::loop_match];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Expression)]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::LoopMatch;
 }
 
@@ -15,5 +12,6 @@ pub(crate) struct ConstContinueParser;
 impl<S: Stage> NoArgsAttributeParser<S> for ConstContinueParser {
     const PATH: &[Symbol] = &[sym::const_continue];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Expression)]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::ConstContinue;
 }
diff --git a/compiler/rustc_attr_parsing/src/attributes/macro_attrs.rs b/compiler/rustc_attr_parsing/src/attributes/macro_attrs.rs
index a1166bf9ac5..180130c7be4 100644
--- a/compiler/rustc_attr_parsing/src/attributes/macro_attrs.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/macro_attrs.rs
@@ -1,18 +1,14 @@
 use rustc_errors::DiagArgValue;
-use rustc_feature::{AttributeTemplate, template};
-use rustc_hir::attrs::{AttributeKind, MacroUseArgs};
-use rustc_span::{Span, Symbol, sym};
-use thin_vec::ThinVec;
+use rustc_hir::attrs::MacroUseArgs;
 
-use crate::attributes::{AcceptMapping, AttributeParser, NoArgsAttributeParser, OnDuplicate};
-use crate::context::{AcceptContext, FinalizeContext, Stage};
-use crate::parser::ArgParser;
-use crate::session_diagnostics;
+use super::prelude::*;
+use crate::session_diagnostics::IllFormedAttributeInputLint;
 
 pub(crate) struct MacroEscapeParser;
 impl<S: Stage> NoArgsAttributeParser<S> for MacroEscapeParser {
     const PATH: &[Symbol] = &[sym::macro_escape];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const ALLOWED_TARGETS: AllowedTargets = MACRO_USE_ALLOWED_TARGETS;
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::MacroEscape;
 }
 
@@ -35,6 +31,12 @@ const MACRO_USE_TEMPLATE: AttributeTemplate = template!(
     Word, List: &["name1, name2, ..."],
     "https://doc.rust-lang.org/reference/macros-by-example.html#the-macro_use-attribute"
 );
+const MACRO_USE_ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowListWarnRest(&[
+    Allow(Target::Mod),
+    Allow(Target::ExternCrate),
+    Allow(Target::Crate),
+    Error(Target::WherePredicate),
+]);
 
 impl<S: Stage> AttributeParser<S> for MacroUseParser {
     const ATTRIBUTES: AcceptMapping<Self, S> = &[(
@@ -99,8 +101,8 @@ impl<S: Stage> AttributeParser<S> for MacroUseParser {
                     }
                 }
                 ArgParser::NameValue(_) => {
-                    let suggestions = MACRO_USE_TEMPLATE.suggestions(false, sym::macro_use);
-                    cx.emit_err(session_diagnostics::IllFormedAttributeInputLint {
+                    let suggestions = MACRO_USE_TEMPLATE.suggestions(cx.attr_style, sym::macro_use);
+                    cx.emit_err(IllFormedAttributeInputLint {
                         num_suggestions: suggestions.len(),
                         suggestions: DiagArgValue::StrListSepByAnd(
                             suggestions.into_iter().map(|s| format!("`{s}`").into()).collect(),
@@ -111,6 +113,7 @@ impl<S: Stage> AttributeParser<S> for MacroUseParser {
             }
         },
     )];
+    const ALLOWED_TARGETS: AllowedTargets = MACRO_USE_ALLOWED_TARGETS;
 
     fn finalize(self, _cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
         Some(AttributeKind::MacroUse { span: self.first_span?, arguments: self.state })
@@ -122,5 +125,11 @@ pub(crate) struct AllowInternalUnsafeParser;
 impl<S: Stage> NoArgsAttributeParser<S> for AllowInternalUnsafeParser {
     const PATH: &[Symbol] = &[sym::allow_internal_unsafe];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Ignore;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Fn),
+        Allow(Target::MacroDef),
+        Warn(Target::Field),
+        Warn(Target::Arm),
+    ]);
     const CREATE: fn(Span) -> AttributeKind = |span| AttributeKind::AllowInternalUnsafe(span);
 }
diff --git a/compiler/rustc_attr_parsing/src/attributes/mod.rs b/compiler/rustc_attr_parsing/src/attributes/mod.rs
index f7946ade6d2..043bc925eac 100644
--- a/compiler/rustc_attr_parsing/src/attributes/mod.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/mod.rs
@@ -7,16 +7,20 @@
 //! Specifically, you might not care about managing the state of your [`AttributeParser`]
 //! state machine yourself. In this case you can choose to implement:
 //!
-//! - [`SingleAttributeParser`]: makes it easy to implement an attribute which should error if it
+//! - [`SingleAttributeParser`](crate::attributes::SingleAttributeParser): makes it easy to implement an attribute which should error if it
 //! appears more than once in a list of attributes
-//! - [`CombineAttributeParser`]: makes it easy to implement an attribute which should combine the
+//! - [`CombineAttributeParser`](crate::attributes::CombineAttributeParser): makes it easy to implement an attribute which should combine the
 //! contents of attributes, if an attribute appear multiple times in a list
 //!
+//! By default, attributes are allowed anywhere. When adding an attribute that should only be used
+//! at the crate root, consider setting the `TYPE` in the parser trait to
+//! [`AttributeType::CrateLevel`](rustc_feature::AttributeType::CrateLevel).
+//!
 //! Attributes should be added to `crate::context::ATTRIBUTE_PARSERS` to be parsed.
 
 use std::marker::PhantomData;
 
-use rustc_feature::{AttributeTemplate, template};
+use rustc_feature::{AttributeTemplate, AttributeType, template};
 use rustc_hir::attrs::AttributeKind;
 use rustc_span::{Span, Symbol};
 use thin_vec::ThinVec;
@@ -24,6 +28,10 @@ use thin_vec::ThinVec;
 use crate::context::{AcceptContext, FinalizeContext, Stage};
 use crate::parser::ArgParser;
 use crate::session_diagnostics::UnusedMultiple;
+use crate::target_checking::AllowedTargets;
+
+/// All the parsers require roughly the same imports, so this prelude has most of the often-needed ones.
+mod prelude;
 
 pub(crate) mod allow_unstable;
 pub(crate) mod body;
@@ -31,6 +39,7 @@ pub(crate) mod cfg;
 pub(crate) mod cfg_old;
 pub(crate) mod codegen_attrs;
 pub(crate) mod confusables;
+pub(crate) mod crate_level;
 pub(crate) mod deprecation;
 pub(crate) mod dummy;
 pub(crate) mod inline;
@@ -43,6 +52,7 @@ pub(crate) mod no_implicit_prelude;
 pub(crate) mod non_exhaustive;
 pub(crate) mod path;
 pub(crate) mod proc_macro_attrs;
+pub(crate) mod prototype;
 pub(crate) mod repr;
 pub(crate) mod rustc_internal;
 pub(crate) mod semantics;
@@ -80,6 +90,10 @@ pub(crate) trait AttributeParser<S: Stage>: Default + 'static {
     /// If an attribute has this symbol, the `accept` function will be called on it.
     const ATTRIBUTES: AcceptMapping<Self, S>;
 
+    const ALLOWED_TARGETS: AllowedTargets;
+
+    const TYPE: AttributeType = AttributeType::Normal;
+
     /// The parser has gotten a chance to accept the attributes on an item,
     /// here it can produce an attribute.
     ///
@@ -116,9 +130,13 @@ pub(crate) trait SingleAttributeParser<S: Stage>: 'static {
     /// and this specified whether to, for example, warn or error on the other one.
     const ON_DUPLICATE: OnDuplicate<S>;
 
+    const ALLOWED_TARGETS: AllowedTargets;
+
     /// The template this attribute parser should implement. Used for diagnostics.
     const TEMPLATE: AttributeTemplate;
 
+    const TYPE: AttributeType = AttributeType::Normal;
+
     /// Converts a single syntactical attribute to a single semantic attribute, or [`AttributeKind`]
     fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind>;
 }
@@ -163,6 +181,9 @@ impl<T: SingleAttributeParser<S>, S: Stage> AttributeParser<S> for Single<T, S>
             }
         },
     )];
+    const ALLOWED_TARGETS: AllowedTargets = T::ALLOWED_TARGETS;
+
+    const TYPE: AttributeType = T::TYPE;
 
     fn finalize(self, _cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
         Some(self.1?.0)
@@ -247,6 +268,8 @@ pub(crate) enum AttributeOrder {
 pub(crate) trait NoArgsAttributeParser<S: Stage>: 'static {
     const PATH: &[Symbol];
     const ON_DUPLICATE: OnDuplicate<S>;
+    const ALLOWED_TARGETS: AllowedTargets;
+    const TYPE: AttributeType = AttributeType::Normal;
 
     /// Create the [`AttributeKind`] given attribute's [`Span`].
     const CREATE: fn(Span) -> AttributeKind;
@@ -264,7 +287,9 @@ impl<T: NoArgsAttributeParser<S>, S: Stage> SingleAttributeParser<S> for Without
     const PATH: &[Symbol] = T::PATH;
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
     const ON_DUPLICATE: OnDuplicate<S> = T::ON_DUPLICATE;
+    const ALLOWED_TARGETS: AllowedTargets = T::ALLOWED_TARGETS;
     const TEMPLATE: AttributeTemplate = template!(Word);
+    const TYPE: AttributeType = T::TYPE;
 
     fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
         if let Err(span) = args.no_args() {
@@ -293,9 +318,13 @@ pub(crate) trait CombineAttributeParser<S: Stage>: 'static {
     ///  where `x` is a vec of these individual reprs.
     const CONVERT: ConvertFn<Self::Item>;
 
+    const ALLOWED_TARGETS: AllowedTargets;
+
     /// The template this attribute parser should implement. Used for diagnostics.
     const TEMPLATE: AttributeTemplate;
 
+    const TYPE: AttributeType = AttributeType::Normal;
+
     /// Converts a single syntactical attribute to a number of elements of the semantic attribute, or [`AttributeKind`]
     fn extend<'c>(
         cx: &'c mut AcceptContext<'_, '_, S>,
@@ -324,15 +353,14 @@ impl<T: CombineAttributeParser<S>, S: Stage> Default for Combine<T, S> {
 }
 
 impl<T: CombineAttributeParser<S>, S: Stage> AttributeParser<S> for Combine<T, S> {
-    const ATTRIBUTES: AcceptMapping<Self, S> = &[(
-        T::PATH,
-        <T as CombineAttributeParser<S>>::TEMPLATE,
-        |group: &mut Combine<T, S>, cx, args| {
+    const ATTRIBUTES: AcceptMapping<Self, S> =
+        &[(T::PATH, T::TEMPLATE, |group: &mut Combine<T, S>, cx, args| {
             // Keep track of the span of the first attribute, for diagnostics
             group.first_span.get_or_insert(cx.attr_span);
             group.items.extend(T::extend(cx, args))
-        },
-    )];
+        })];
+    const ALLOWED_TARGETS: AllowedTargets = T::ALLOWED_TARGETS;
+    const TYPE: AttributeType = T::TYPE;
 
     fn finalize(self, _cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
         if let Some(first_span) = self.first_span {
diff --git a/compiler/rustc_attr_parsing/src/attributes/must_use.rs b/compiler/rustc_attr_parsing/src/attributes/must_use.rs
index c88bb5a69e5..e6a5141d783 100644
--- a/compiler/rustc_attr_parsing/src/attributes/must_use.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/must_use.rs
@@ -1,12 +1,7 @@
 use rustc_errors::DiagArgValue;
-use rustc_feature::{AttributeTemplate, template};
-use rustc_hir::attrs::AttributeKind;
-use rustc_span::{Symbol, sym};
 
-use crate::attributes::{AttributeOrder, OnDuplicate, SingleAttributeParser};
-use crate::context::{AcceptContext, Stage};
-use crate::parser::ArgParser;
-use crate::session_diagnostics;
+use super::prelude::*;
+use crate::session_diagnostics::IllFormedAttributeInputLint;
 
 pub(crate) struct MustUseParser;
 
@@ -14,6 +9,21 @@ impl<S: Stage> SingleAttributeParser<S> for MustUseParser {
     const PATH: &[Symbol] = &[sym::must_use];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowListWarnRest(&[
+        Allow(Target::Fn),
+        Allow(Target::Enum),
+        Allow(Target::Struct),
+        Allow(Target::Union),
+        Allow(Target::Method(MethodKind::Trait { body: false })),
+        Allow(Target::Method(MethodKind::Trait { body: true })),
+        Allow(Target::Method(MethodKind::Inherent)),
+        Allow(Target::ForeignFn),
+        // `impl Trait` in return position can trip
+        // `unused_must_use` if `Trait` is marked as
+        // `#[must_use]`
+        Allow(Target::Trait),
+        Error(Target::WherePredicate),
+    ]);
     const TEMPLATE: AttributeTemplate = template!(
         Word, NameValueStr: "reason",
         "https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-must_use-attribute"
@@ -35,9 +45,9 @@ impl<S: Stage> SingleAttributeParser<S> for MustUseParser {
                     Some(value_str)
                 }
                 ArgParser::List(_) => {
-                    let suggestions =
-                        <Self as SingleAttributeParser<S>>::TEMPLATE.suggestions(false, "must_use");
-                    cx.emit_err(session_diagnostics::IllFormedAttributeInputLint {
+                    let suggestions = <Self as SingleAttributeParser<S>>::TEMPLATE
+                        .suggestions(cx.attr_style, "must_use");
+                    cx.emit_err(IllFormedAttributeInputLint {
                         num_suggestions: suggestions.len(),
                         suggestions: DiagArgValue::StrListSepByAnd(
                             suggestions.into_iter().map(|s| format!("`{s}`").into()).collect(),
diff --git a/compiler/rustc_attr_parsing/src/attributes/no_implicit_prelude.rs b/compiler/rustc_attr_parsing/src/attributes/no_implicit_prelude.rs
index 40f8d00685e..40073ea0f46 100644
--- a/compiler/rustc_attr_parsing/src/attributes/no_implicit_prelude.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/no_implicit_prelude.rs
@@ -1,13 +1,11 @@
-use rustc_hir::attrs::AttributeKind;
-use rustc_span::{Span, sym};
-
-use crate::attributes::{NoArgsAttributeParser, OnDuplicate};
-use crate::context::Stage;
+use super::prelude::*;
 
 pub(crate) struct NoImplicitPreludeParser;
 
 impl<S: Stage> NoArgsAttributeParser<S> for NoImplicitPreludeParser {
     const PATH: &[rustc_span::Symbol] = &[sym::no_implicit_prelude];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const ALLOWED_TARGETS: AllowedTargets =
+        AllowedTargets::AllowListWarnRest(&[Allow(Target::Mod), Allow(Target::Crate)]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::NoImplicitPrelude;
 }
diff --git a/compiler/rustc_attr_parsing/src/attributes/non_exhaustive.rs b/compiler/rustc_attr_parsing/src/attributes/non_exhaustive.rs
index 361ac8e959d..fc41c073fd2 100644
--- a/compiler/rustc_attr_parsing/src/attributes/non_exhaustive.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/non_exhaustive.rs
@@ -1,13 +1,25 @@
+use rustc_hir::Target;
 use rustc_hir::attrs::AttributeKind;
 use rustc_span::{Span, Symbol, sym};
 
 use crate::attributes::{NoArgsAttributeParser, OnDuplicate};
 use crate::context::Stage;
+use crate::target_checking::AllowedTargets;
+use crate::target_checking::Policy::{Allow, Warn};
 
 pub(crate) struct NonExhaustiveParser;
 
 impl<S: Stage> NoArgsAttributeParser<S> for NonExhaustiveParser {
     const PATH: &[Symbol] = &[sym::non_exhaustive];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Enum),
+        Allow(Target::Struct),
+        Allow(Target::Variant),
+        Warn(Target::Field),
+        Warn(Target::Arm),
+        Warn(Target::MacroDef),
+        Warn(Target::MacroCall),
+    ]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::NonExhaustive;
 }
diff --git a/compiler/rustc_attr_parsing/src/attributes/path.rs b/compiler/rustc_attr_parsing/src/attributes/path.rs
index c1c3de8cbfc..e4cb806bb42 100644
--- a/compiler/rustc_attr_parsing/src/attributes/path.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/path.rs
@@ -1,10 +1,4 @@
-use rustc_feature::{AttributeTemplate, template};
-use rustc_hir::attrs::AttributeKind;
-use rustc_span::{Symbol, sym};
-
-use crate::attributes::{AttributeOrder, OnDuplicate, SingleAttributeParser};
-use crate::context::{AcceptContext, Stage};
-use crate::parser::ArgParser;
+use super::prelude::*;
 
 pub(crate) struct PathParser;
 
@@ -12,6 +6,8 @@ impl<S: Stage> SingleAttributeParser<S> for PathParser {
     const PATH: &[Symbol] = &[sym::path];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
+    const ALLOWED_TARGETS: AllowedTargets =
+        AllowedTargets::AllowListWarnRest(&[Allow(Target::Mod), Error(Target::Crate)]);
     const TEMPLATE: AttributeTemplate = template!(
         NameValueStr: "file",
         "https://doc.rust-lang.org/reference/items/modules.html#the-path-attribute"
diff --git a/compiler/rustc_attr_parsing/src/attributes/prelude.rs b/compiler/rustc_attr_parsing/src/attributes/prelude.rs
new file mode 100644
index 00000000000..2bcdee55c75
--- /dev/null
+++ b/compiler/rustc_attr_parsing/src/attributes/prelude.rs
@@ -0,0 +1,20 @@
+// parsing
+// templates
+pub(super) use rustc_feature::{AttributeTemplate, template};
+// data structures
+pub(super) use rustc_hir::attrs::AttributeKind;
+pub(super) use rustc_hir::lints::AttributeLintKind;
+pub(super) use rustc_hir::{MethodKind, Target};
+pub(super) use rustc_span::{DUMMY_SP, Ident, Span, Symbol, sym};
+pub(super) use thin_vec::ThinVec;
+
+pub(super) use crate::attributes::{
+    AcceptMapping, AttributeOrder, AttributeParser, CombineAttributeParser, ConvertFn,
+    NoArgsAttributeParser, OnDuplicate, SingleAttributeParser,
+};
+// contexts
+pub(super) use crate::context::{AcceptContext, FinalizeContext, Stage};
+pub(super) use crate::parser::*;
+// target checking
+pub(super) use crate::target_checking::Policy::{Allow, Error, Warn};
+pub(super) use crate::target_checking::{ALL_TARGETS, AllowedTargets};
diff --git a/compiler/rustc_attr_parsing/src/attributes/proc_macro_attrs.rs b/compiler/rustc_attr_parsing/src/attributes/proc_macro_attrs.rs
index b267980914c..b9929d6f1f8 100644
--- a/compiler/rustc_attr_parsing/src/attributes/proc_macro_attrs.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/proc_macro_attrs.rs
@@ -1,18 +1,13 @@
-use rustc_feature::{AttributeTemplate, template};
-use rustc_hir::attrs::AttributeKind;
-use rustc_span::{Span, Symbol, sym};
-use thin_vec::ThinVec;
+use super::prelude::*;
 
-use crate::attributes::{
-    AttributeOrder, NoArgsAttributeParser, OnDuplicate, SingleAttributeParser,
-};
-use crate::context::{AcceptContext, Stage};
-use crate::parser::ArgParser;
+const PROC_MACRO_ALLOWED_TARGETS: AllowedTargets =
+    AllowedTargets::AllowList(&[Allow(Target::Fn), Warn(Target::Crate), Warn(Target::MacroCall)]);
 
 pub(crate) struct ProcMacroParser;
 impl<S: Stage> NoArgsAttributeParser<S> for ProcMacroParser {
     const PATH: &[Symbol] = &[sym::proc_macro];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = PROC_MACRO_ALLOWED_TARGETS;
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::ProcMacro;
 }
 
@@ -20,6 +15,7 @@ pub(crate) struct ProcMacroAttributeParser;
 impl<S: Stage> NoArgsAttributeParser<S> for ProcMacroAttributeParser {
     const PATH: &[Symbol] = &[sym::proc_macro_attribute];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = PROC_MACRO_ALLOWED_TARGETS;
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::ProcMacroAttribute;
 }
 
@@ -28,6 +24,7 @@ impl<S: Stage> SingleAttributeParser<S> for ProcMacroDeriveParser {
     const PATH: &[Symbol] = &[sym::proc_macro_derive];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = PROC_MACRO_ALLOWED_TARGETS;
     const TEMPLATE: AttributeTemplate = template!(
         List: &["TraitName", "TraitName, attributes(name1, name2, ...)"],
         "https://doc.rust-lang.org/reference/procedural-macros.html#derive-macros"
@@ -48,6 +45,7 @@ impl<S: Stage> SingleAttributeParser<S> for RustcBuiltinMacroParser {
     const PATH: &[Symbol] = &[sym::rustc_builtin_macro];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::MacroDef)]);
     const TEMPLATE: AttributeTemplate =
         template!(List: &["TraitName", "TraitName, attributes(name1, name2, ...)"]);
 
@@ -102,7 +100,7 @@ fn parse_derive_like<S: Stage>(
             return None;
         };
         if !attr_list.path().word_is(sym::attributes) {
-            cx.expected_specific_argument(attrs.span(), vec!["attributes"]);
+            cx.expected_specific_argument(attrs.span(), &[sym::attributes]);
             return None;
         }
         let Some(attr_list) = attr_list.args().list() else {
diff --git a/compiler/rustc_attr_parsing/src/attributes/prototype.rs b/compiler/rustc_attr_parsing/src/attributes/prototype.rs
new file mode 100644
index 00000000000..80fe82bf542
--- /dev/null
+++ b/compiler/rustc_attr_parsing/src/attributes/prototype.rs
@@ -0,0 +1,141 @@
+//! Attributes that are only used on function prototypes.
+
+use rustc_feature::{AttributeTemplate, template};
+use rustc_hir::Target;
+use rustc_hir::attrs::{AttributeKind, MirDialect, MirPhase};
+use rustc_span::{Span, Symbol, sym};
+
+use super::{AttributeOrder, OnDuplicate};
+use crate::attributes::SingleAttributeParser;
+use crate::context::{AcceptContext, Stage};
+use crate::parser::ArgParser;
+use crate::target_checking::AllowedTargets;
+use crate::target_checking::Policy::Allow;
+
+pub(crate) struct CustomMirParser;
+
+impl<S: Stage> SingleAttributeParser<S> for CustomMirParser {
+    const PATH: &[rustc_span::Symbol] = &[sym::custom_mir];
+
+    const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
+
+    const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Fn)]);
+
+    const TEMPLATE: AttributeTemplate = template!(List: &[r#"dialect = "...", phase = "...""#]);
+
+    fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
+        let Some(list) = args.list() else {
+            cx.expected_list(cx.attr_span);
+            return None;
+        };
+
+        let mut dialect = None;
+        let mut phase = None;
+        let mut failed = false;
+
+        for item in list.mixed() {
+            let Some(meta_item) = item.meta_item() else {
+                cx.expected_name_value(item.span(), None);
+                failed = true;
+                break;
+            };
+
+            if let Some(arg) = meta_item.word_is(sym::dialect) {
+                extract_value(cx, sym::dialect, arg, meta_item.span(), &mut dialect, &mut failed);
+            } else if let Some(arg) = meta_item.word_is(sym::phase) {
+                extract_value(cx, sym::phase, arg, meta_item.span(), &mut phase, &mut failed);
+            } else if let Some(word) = meta_item.path().word() {
+                let word = word.to_string();
+                cx.unknown_key(meta_item.span(), word, &["dialect", "phase"]);
+                failed = true;
+            } else {
+                cx.expected_name_value(meta_item.span(), None);
+                failed = true;
+            };
+        }
+
+        let dialect = parse_dialect(cx, dialect, &mut failed);
+        let phase = parse_phase(cx, phase, &mut failed);
+
+        if failed {
+            return None;
+        }
+
+        Some(AttributeKind::CustomMir(dialect, phase, cx.attr_span))
+    }
+}
+
+fn extract_value<S: Stage>(
+    cx: &mut AcceptContext<'_, '_, S>,
+    key: Symbol,
+    arg: &ArgParser<'_>,
+    span: Span,
+    out_val: &mut Option<(Symbol, Span)>,
+    failed: &mut bool,
+) {
+    if out_val.is_some() {
+        cx.duplicate_key(span, key);
+        *failed = true;
+        return;
+    }
+
+    let Some(val) = arg.name_value() else {
+        cx.expected_single_argument(arg.span().unwrap_or(span));
+        *failed = true;
+        return;
+    };
+
+    let Some(value_sym) = val.value_as_str() else {
+        cx.expected_string_literal(val.value_span, Some(val.value_as_lit()));
+        *failed = true;
+        return;
+    };
+
+    *out_val = Some((value_sym, val.value_span));
+}
+
+fn parse_dialect<S: Stage>(
+    cx: &mut AcceptContext<'_, '_, S>,
+    dialect: Option<(Symbol, Span)>,
+    failed: &mut bool,
+) -> Option<(MirDialect, Span)> {
+    let (dialect, span) = dialect?;
+
+    let dialect = match dialect {
+        sym::analysis => MirDialect::Analysis,
+        sym::built => MirDialect::Built,
+        sym::runtime => MirDialect::Runtime,
+
+        _ => {
+            cx.expected_specific_argument(span, &[sym::analysis, sym::built, sym::runtime]);
+            *failed = true;
+            return None;
+        }
+    };
+
+    Some((dialect, span))
+}
+
+fn parse_phase<S: Stage>(
+    cx: &mut AcceptContext<'_, '_, S>,
+    phase: Option<(Symbol, Span)>,
+    failed: &mut bool,
+) -> Option<(MirPhase, Span)> {
+    let (phase, span) = phase?;
+
+    let phase = match phase {
+        sym::initial => MirPhase::Initial,
+        sym::post_cleanup => MirPhase::PostCleanup,
+        sym::optimized => MirPhase::Optimized,
+
+        _ => {
+            cx.expected_specific_argument(span, &[sym::initial, sym::post_cleanup, sym::optimized]);
+            *failed = true;
+            return None;
+        }
+    };
+
+    Some((phase, span))
+}
diff --git a/compiler/rustc_attr_parsing/src/attributes/repr.rs b/compiler/rustc_attr_parsing/src/attributes/repr.rs
index 996d2af5f37..23aabd15597 100644
--- a/compiler/rustc_attr_parsing/src/attributes/repr.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/repr.rs
@@ -1,14 +1,9 @@
 use rustc_abi::Align;
 use rustc_ast::{IntTy, LitIntType, LitKind, UintTy};
-use rustc_feature::{AttributeTemplate, template};
-use rustc_hir::attrs::{AttributeKind, IntType, ReprAttr};
-use rustc_span::{DUMMY_SP, Span, Symbol, sym};
+use rustc_hir::attrs::{IntType, ReprAttr};
 
-use super::{AcceptMapping, AttributeParser, CombineAttributeParser, ConvertFn, FinalizeContext};
-use crate::context::{AcceptContext, Stage};
-use crate::parser::{ArgParser, MetaItemListParser, MetaItemParser};
-use crate::session_diagnostics;
-use crate::session_diagnostics::IncorrectReprFormatGenericCause;
+use super::prelude::*;
+use crate::session_diagnostics::{self, IncorrectReprFormatGenericCause};
 
 /// Parse #[repr(...)] forms.
 ///
@@ -60,6 +55,10 @@ impl<S: Stage> CombineAttributeParser<S> for ReprParser {
 
         reprs
     }
+
+    //FIXME Still checked fully in `check_attr.rs`
+    //This one is slightly more complicated because the allowed targets depend on the arguments
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(ALL_TARGETS);
 }
 
 macro_rules! int_pat {
@@ -318,6 +317,14 @@ impl AlignParser {
 
 impl<S: Stage> AttributeParser<S> for AlignParser {
     const ATTRIBUTES: AcceptMapping<Self, S> = &[(Self::PATH, Self::TEMPLATE, Self::parse)];
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Fn),
+        Allow(Target::Method(MethodKind::Inherent)),
+        Allow(Target::Method(MethodKind::Trait { body: true })),
+        Allow(Target::Method(MethodKind::TraitImpl)),
+        Allow(Target::Method(MethodKind::Trait { body: false })),
+        Allow(Target::ForeignFn),
+    ]);
 
     fn finalize(self, _cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
         let (align, span) = self.0?;
diff --git a/compiler/rustc_attr_parsing/src/attributes/rustc_internal.rs b/compiler/rustc_attr_parsing/src/attributes/rustc_internal.rs
index 1a668b4416f..a995549fc7c 100644
--- a/compiler/rustc_attr_parsing/src/attributes/rustc_internal.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/rustc_internal.rs
@@ -1,10 +1,5 @@
-use rustc_feature::{AttributeTemplate, template};
-use rustc_hir::attrs::AttributeKind;
-use rustc_span::{Symbol, sym};
-
-use crate::attributes::{AttributeOrder, OnDuplicate, SingleAttributeParser};
-use crate::context::{AcceptContext, Stage, parse_single_integer};
-use crate::parser::ArgParser;
+use super::prelude::*;
+use super::util::parse_single_integer;
 
 pub(crate) struct RustcLayoutScalarValidRangeStart;
 
@@ -12,6 +7,7 @@ impl<S: Stage> SingleAttributeParser<S> for RustcLayoutScalarValidRangeStart {
     const PATH: &'static [Symbol] = &[sym::rustc_layout_scalar_valid_range_start];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepInnermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Struct)]);
     const TEMPLATE: AttributeTemplate = template!(List: &["start"]);
 
     fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
@@ -26,6 +22,7 @@ impl<S: Stage> SingleAttributeParser<S> for RustcLayoutScalarValidRangeEnd {
     const PATH: &'static [Symbol] = &[sym::rustc_layout_scalar_valid_range_end];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepInnermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Struct)]);
     const TEMPLATE: AttributeTemplate = template!(List: &["end"]);
 
     fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
@@ -40,6 +37,7 @@ impl<S: Stage> SingleAttributeParser<S> for RustcObjectLifetimeDefaultParser {
     const PATH: &[rustc_span::Symbol] = &[sym::rustc_object_lifetime_default];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepInnermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Struct)]);
     const TEMPLATE: AttributeTemplate = template!(Word);
 
     fn convert(cx: &mut AcceptContext<'_, '_, S>, args: &ArgParser<'_>) -> Option<AttributeKind> {
diff --git a/compiler/rustc_attr_parsing/src/attributes/semantics.rs b/compiler/rustc_attr_parsing/src/attributes/semantics.rs
index 70a8a002099..d7f62483297 100644
--- a/compiler/rustc_attr_parsing/src/attributes/semantics.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/semantics.rs
@@ -1,12 +1,9 @@
-use rustc_hir::attrs::AttributeKind;
-use rustc_span::{Span, Symbol, sym};
-
-use crate::attributes::{NoArgsAttributeParser, OnDuplicate};
-use crate::context::Stage;
+use super::prelude::*;
 
 pub(crate) struct MayDangleParser;
 impl<S: Stage> NoArgsAttributeParser<S> for MayDangleParser {
     const PATH: &[Symbol] = &[sym::may_dangle];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(ALL_TARGETS); //FIXME Still checked fully in `check_attr.rs`
     const CREATE: fn(span: Span) -> AttributeKind = AttributeKind::MayDangle;
 }
diff --git a/compiler/rustc_attr_parsing/src/attributes/stability.rs b/compiler/rustc_attr_parsing/src/attributes/stability.rs
index c6707f5048b..b94e23477ff 100644
--- a/compiler/rustc_attr_parsing/src/attributes/stability.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/stability.rs
@@ -1,19 +1,13 @@
 use std::num::NonZero;
 
 use rustc_errors::ErrorGuaranteed;
-use rustc_feature::template;
-use rustc_hir::attrs::AttributeKind;
 use rustc_hir::{
-    DefaultBodyStability, PartialConstStability, Stability, StabilityLevel, StableSince,
-    UnstableReason, VERSION_PLACEHOLDER,
+    DefaultBodyStability, MethodKind, PartialConstStability, Stability, StabilityLevel,
+    StableSince, Target, UnstableReason, VERSION_PLACEHOLDER,
 };
-use rustc_span::{Ident, Span, Symbol, sym};
 
+use super::prelude::*;
 use super::util::parse_version;
-use super::{AcceptMapping, AttributeParser, OnDuplicate};
-use crate::attributes::NoArgsAttributeParser;
-use crate::context::{AcceptContext, FinalizeContext, Stage};
-use crate::parser::{ArgParser, MetaItemParser};
 use crate::session_diagnostics::{self, UnsupportedLiteralReason};
 
 macro_rules! reject_outside_std {
@@ -26,6 +20,36 @@ macro_rules! reject_outside_std {
     };
 }
 
+const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+    Allow(Target::Fn),
+    Allow(Target::Struct),
+    Allow(Target::Enum),
+    Allow(Target::Union),
+    Allow(Target::Method(MethodKind::Inherent)),
+    Allow(Target::Method(MethodKind::Trait { body: false })),
+    Allow(Target::Method(MethodKind::Trait { body: true })),
+    Allow(Target::Method(MethodKind::TraitImpl)),
+    Allow(Target::Impl { of_trait: false }),
+    Allow(Target::Impl { of_trait: true }),
+    Allow(Target::MacroDef),
+    Allow(Target::Crate),
+    Allow(Target::Mod),
+    Allow(Target::Use), // FIXME I don't think this does anything?
+    Allow(Target::Const),
+    Allow(Target::AssocConst),
+    Allow(Target::AssocTy),
+    Allow(Target::Trait),
+    Allow(Target::TraitAlias),
+    Allow(Target::TyAlias),
+    Allow(Target::Variant),
+    Allow(Target::Field),
+    Allow(Target::Param),
+    Allow(Target::Static),
+    Allow(Target::ForeignFn),
+    Allow(Target::ForeignStatic),
+    Allow(Target::ExternCrate),
+]);
+
 #[derive(Default)]
 pub(crate) struct StabilityParser {
     allowed_through_unstable_modules: Option<Symbol>,
@@ -87,6 +111,7 @@ impl<S: Stage> AttributeParser<S> for StabilityParser {
             },
         ),
     ];
+    const ALLOWED_TARGETS: AllowedTargets = ALLOWED_TARGETS;
 
     fn finalize(mut self, cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
         if let Some(atum) = self.allowed_through_unstable_modules {
@@ -142,6 +167,7 @@ impl<S: Stage> AttributeParser<S> for BodyStabilityParser {
             }
         },
     )];
+    const ALLOWED_TARGETS: AllowedTargets = ALLOWED_TARGETS;
 
     fn finalize(self, _cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
         let (stability, span) = self.stability?;
@@ -154,6 +180,10 @@ pub(crate) struct ConstStabilityIndirectParser;
 impl<S: Stage> NoArgsAttributeParser<S> for ConstStabilityIndirectParser {
     const PATH: &[Symbol] = &[sym::rustc_const_stable_indirect];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Ignore;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Fn),
+        Allow(Target::Method(MethodKind::Inherent)),
+    ]);
     const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::ConstStabilityIndirect;
 }
 
@@ -213,6 +243,7 @@ impl<S: Stage> AttributeParser<S> for ConstStabilityParser {
             this.promotable = true;
         }),
     ];
+    const ALLOWED_TARGETS: AllowedTargets = ALLOWED_TARGETS;
 
     fn finalize(mut self, cx: &FinalizeContext<'_, '_, S>) -> Option<AttributeKind> {
         if self.promotable {
diff --git a/compiler/rustc_attr_parsing/src/attributes/test_attrs.rs b/compiler/rustc_attr_parsing/src/attributes/test_attrs.rs
index 3267855fb0d..510ff1ded49 100644
--- a/compiler/rustc_attr_parsing/src/attributes/test_attrs.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/test_attrs.rs
@@ -1,11 +1,4 @@
-use rustc_feature::{AttributeTemplate, template};
-use rustc_hir::attrs::AttributeKind;
-use rustc_hir::lints::AttributeLintKind;
-use rustc_span::{Symbol, sym};
-
-use crate::attributes::{AttributeOrder, OnDuplicate, SingleAttributeParser};
-use crate::context::{AcceptContext, Stage};
-use crate::parser::ArgParser;
+use super::prelude::*;
 
 pub(crate) struct IgnoreParser;
 
@@ -13,6 +6,8 @@ impl<S: Stage> SingleAttributeParser<S> for IgnoreParser {
     const PATH: &[Symbol] = &[sym::ignore];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const ALLOWED_TARGETS: AllowedTargets =
+        AllowedTargets::AllowListWarnRest(&[Allow(Target::Fn), Error(Target::WherePredicate)]);
     const TEMPLATE: AttributeTemplate = template!(
         Word, NameValueStr: "reason",
         "https://doc.rust-lang.org/reference/attributes/testing.html#the-ignore-attribute"
@@ -26,7 +21,7 @@ impl<S: Stage> SingleAttributeParser<S> for IgnoreParser {
                 ArgParser::NameValue(name_value) => {
                     let Some(str_value) = name_value.value_as_str() else {
                         let suggestions = <Self as SingleAttributeParser<S>>::TEMPLATE
-                            .suggestions(false, "ignore");
+                            .suggestions(cx.attr_style, "ignore");
                         let span = cx.attr_span;
                         cx.emit_lint(
                             AttributeLintKind::IllFormedAttributeInput { suggestions },
@@ -37,8 +32,8 @@ impl<S: Stage> SingleAttributeParser<S> for IgnoreParser {
                     Some(str_value)
                 }
                 ArgParser::List(_) => {
-                    let suggestions =
-                        <Self as SingleAttributeParser<S>>::TEMPLATE.suggestions(false, "ignore");
+                    let suggestions = <Self as SingleAttributeParser<S>>::TEMPLATE
+                        .suggestions(cx.attr_style, "ignore");
                     let span = cx.attr_span;
                     cx.emit_lint(AttributeLintKind::IllFormedAttributeInput { suggestions }, span);
                     return None;
@@ -54,6 +49,8 @@ impl<S: Stage> SingleAttributeParser<S> for ShouldPanicParser {
     const PATH: &[Symbol] = &[sym::should_panic];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepOutermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::WarnButFutureError;
+    const ALLOWED_TARGETS: AllowedTargets =
+        AllowedTargets::AllowListWarnRest(&[Allow(Target::Fn), Error(Target::WherePredicate)]);
     const TEMPLATE: AttributeTemplate = template!(
         Word, List: &[r#"expected = "reason""#], NameValueStr: "reason",
         "https://doc.rust-lang.org/reference/attributes/testing.html#the-should_panic-attribute"
@@ -84,7 +81,7 @@ impl<S: Stage> SingleAttributeParser<S> for ShouldPanicParser {
                         return None;
                     };
                     if !single.path().word_is(sym::expected) {
-                        cx.expected_specific_argument_strings(list.span, vec!["expected"]);
+                        cx.expected_specific_argument_strings(list.span, &[sym::expected]);
                         return None;
                     }
                     let Some(nv) = single.args().name_value() else {
diff --git a/compiler/rustc_attr_parsing/src/attributes/traits.rs b/compiler/rustc_attr_parsing/src/attributes/traits.rs
index 8514d799aa4..fbd9a480fbb 100644
--- a/compiler/rustc_attr_parsing/src/attributes/traits.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/traits.rs
@@ -1,20 +1,22 @@
-use core::mem;
+use std::mem;
 
-use rustc_feature::{AttributeTemplate, template};
-use rustc_hir::attrs::AttributeKind;
-use rustc_span::{Span, Symbol, sym};
+use rustc_feature::AttributeType;
 
+use super::prelude::*;
 use crate::attributes::{
     AttributeOrder, NoArgsAttributeParser, OnDuplicate, SingleAttributeParser,
 };
 use crate::context::{AcceptContext, Stage};
 use crate::parser::ArgParser;
+use crate::target_checking::Policy::{Allow, Warn};
+use crate::target_checking::{ALL_TARGETS, AllowedTargets};
 
 pub(crate) struct SkipDuringMethodDispatchParser;
 impl<S: Stage> SingleAttributeParser<S> for SkipDuringMethodDispatchParser {
     const PATH: &[Symbol] = &[sym::rustc_skip_during_method_dispatch];
     const ATTRIBUTE_ORDER: AttributeOrder = AttributeOrder::KeepInnermost;
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Trait)]);
 
     const TEMPLATE: AttributeTemplate = template!(List: &["array, boxed_slice"]);
 
@@ -42,7 +44,7 @@ impl<S: Stage> SingleAttributeParser<S> for SkipDuringMethodDispatchParser {
                 Some(key @ sym::array) => (key, &mut array),
                 Some(key @ sym::boxed_slice) => (key, &mut boxed_slice),
                 _ => {
-                    cx.expected_specific_argument(path.span(), vec!["array", "boxed_slice"]);
+                    cx.expected_specific_argument(path.span(), &[sym::array, sym::boxed_slice]);
                     continue;
                 }
             };
@@ -58,6 +60,7 @@ pub(crate) struct ParenSugarParser;
 impl<S: Stage> NoArgsAttributeParser<S> for ParenSugarParser {
     const PATH: &[Symbol] = &[sym::rustc_paren_sugar];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Trait)]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::ParenSugar;
 }
 
@@ -65,6 +68,7 @@ pub(crate) struct TypeConstParser;
 impl<S: Stage> NoArgsAttributeParser<S> for TypeConstParser {
     const PATH: &[Symbol] = &[sym::type_const];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::AssocConst)]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::TypeConst;
 }
 
@@ -74,6 +78,12 @@ pub(crate) struct MarkerParser;
 impl<S: Stage> NoArgsAttributeParser<S> for MarkerParser {
     const PATH: &[Symbol] = &[sym::marker];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[
+        Allow(Target::Trait),
+        Warn(Target::Field),
+        Warn(Target::Arm),
+        Warn(Target::MacroDef),
+    ]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::Marker;
 }
 
@@ -81,6 +91,7 @@ pub(crate) struct DenyExplicitImplParser;
 impl<S: Stage> NoArgsAttributeParser<S> for DenyExplicitImplParser {
     const PATH: &[Symbol] = &[sym::rustc_deny_explicit_impl];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Trait)]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::DenyExplicitImpl;
 }
 
@@ -88,6 +99,7 @@ pub(crate) struct DoNotImplementViaObjectParser;
 impl<S: Stage> NoArgsAttributeParser<S> for DoNotImplementViaObjectParser {
     const PATH: &[Symbol] = &[sym::rustc_do_not_implement_via_object];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Trait)]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::DoNotImplementViaObject;
 }
 
@@ -98,6 +110,7 @@ pub(crate) struct ConstTraitParser;
 impl<S: Stage> NoArgsAttributeParser<S> for ConstTraitParser {
     const PATH: &[Symbol] = &[sym::const_trait];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Warn;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Trait)]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::ConstTrait;
 }
 
@@ -107,6 +120,7 @@ pub(crate) struct SpecializationTraitParser;
 impl<S: Stage> NoArgsAttributeParser<S> for SpecializationTraitParser {
     const PATH: &[Symbol] = &[sym::rustc_specialization_trait];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Trait)]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::SpecializationTrait;
 }
 
@@ -114,6 +128,7 @@ pub(crate) struct UnsafeSpecializationMarkerParser;
 impl<S: Stage> NoArgsAttributeParser<S> for UnsafeSpecializationMarkerParser {
     const PATH: &[Symbol] = &[sym::rustc_unsafe_specialization_marker];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Trait)]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::UnsafeSpecializationMarker;
 }
 
@@ -123,6 +138,7 @@ pub(crate) struct CoinductiveParser;
 impl<S: Stage> NoArgsAttributeParser<S> for CoinductiveParser {
     const PATH: &[Symbol] = &[sym::rustc_coinductive];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Trait)]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::Coinductive;
 }
 
@@ -130,6 +146,8 @@ pub(crate) struct AllowIncoherentImplParser;
 impl<S: Stage> NoArgsAttributeParser<S> for AllowIncoherentImplParser {
     const PATH: &[Symbol] = &[sym::rustc_allow_incoherent_impl];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets =
+        AllowedTargets::AllowList(&[Allow(Target::Method(MethodKind::Inherent))]);
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::AllowIncoherentImpl;
 }
 
@@ -137,6 +155,8 @@ pub(crate) struct CoherenceIsCoreParser;
 impl<S: Stage> NoArgsAttributeParser<S> for CoherenceIsCoreParser {
     const PATH: &[Symbol] = &[sym::rustc_coherence_is_core];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::Crate)]);
+    const TYPE: AttributeType = AttributeType::CrateLevel;
     const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::CoherenceIsCore;
 }
 
@@ -144,6 +164,8 @@ pub(crate) struct FundamentalParser;
 impl<S: Stage> NoArgsAttributeParser<S> for FundamentalParser {
     const PATH: &[Symbol] = &[sym::fundamental];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets =
+        AllowedTargets::AllowList(&[Allow(Target::Struct), Allow(Target::Trait)]);
     const CREATE: fn(Span) -> AttributeKind = |_| AttributeKind::Fundamental;
 }
 
@@ -151,5 +173,6 @@ pub(crate) struct PointeeParser;
 impl<S: Stage> NoArgsAttributeParser<S> for PointeeParser {
     const PATH: &[Symbol] = &[sym::pointee];
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Error;
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(ALL_TARGETS); //FIXME Still checked fully in `check_attr.rs`
     const CREATE: fn(Span) -> AttributeKind = AttributeKind::Pointee;
 }
diff --git a/compiler/rustc_attr_parsing/src/attributes/transparency.rs b/compiler/rustc_attr_parsing/src/attributes/transparency.rs
index d4d68eb8b27..ea1f5549c4e 100644
--- a/compiler/rustc_attr_parsing/src/attributes/transparency.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/transparency.rs
@@ -1,11 +1,6 @@
-use rustc_feature::{AttributeTemplate, template};
-use rustc_hir::attrs::AttributeKind;
 use rustc_span::hygiene::Transparency;
-use rustc_span::{Symbol, sym};
 
-use super::{AttributeOrder, OnDuplicate, SingleAttributeParser};
-use crate::context::{AcceptContext, Stage};
-use crate::parser::ArgParser;
+use super::prelude::*;
 
 pub(crate) struct TransparencyParser;
 
@@ -18,6 +13,7 @@ impl<S: Stage> SingleAttributeParser<S> for TransparencyParser {
     const ON_DUPLICATE: OnDuplicate<S> = OnDuplicate::Custom(|cx, used, unused| {
         cx.dcx().span_err(vec![used, unused], "multiple macro transparency attributes");
     });
+    const ALLOWED_TARGETS: AllowedTargets = AllowedTargets::AllowList(&[Allow(Target::MacroDef)]);
     const TEMPLATE: AttributeTemplate =
         template!(NameValueStr: ["transparent", "semitransparent", "opaque"]);
 
@@ -33,7 +29,7 @@ impl<S: Stage> SingleAttributeParser<S> for TransparencyParser {
             Some(_) => {
                 cx.expected_specific_argument_strings(
                     nv.value_span,
-                    vec!["transparent", "semitransparent", "opaque"],
+                    &[sym::transparent, sym::semitransparent, sym::opaque],
                 );
                 None
             }
diff --git a/compiler/rustc_attr_parsing/src/attributes/util.rs b/compiler/rustc_attr_parsing/src/attributes/util.rs
index 10134915b27..77e8c32e59d 100644
--- a/compiler/rustc_attr_parsing/src/attributes/util.rs
+++ b/compiler/rustc_attr_parsing/src/attributes/util.rs
@@ -1,8 +1,12 @@
-use rustc_ast::attr::{AttributeExt, first_attr_value_str_by_name};
+use rustc_ast::LitKind;
+use rustc_ast::attr::AttributeExt;
 use rustc_feature::is_builtin_attr_name;
 use rustc_hir::RustcVersion;
 use rustc_span::{Symbol, sym};
 
+use crate::context::{AcceptContext, Stage};
+use crate::parser::ArgParser;
+
 /// Parse a rustc version number written inside string literal in an attribute,
 /// like appears in `since = "1.0.0"`. Suffixes like "-dev" and "-nightly" are
 /// not accepted in this position, unlike when parsing CFG_RELEASE.
@@ -23,10 +27,6 @@ pub fn is_builtin_attr(attr: &impl AttributeExt) -> bool {
     attr.is_doc_comment() || attr.ident().is_some_and(|ident| is_builtin_attr_name(ident.name))
 }
 
-pub fn find_crate_name(attrs: &[impl AttributeExt]) -> Option<Symbol> {
-    first_attr_value_str_by_name(attrs, sym::crate_name)
-}
-
 pub fn is_doc_alias_attrs_contain_symbol<'tcx, T: AttributeExt + 'tcx>(
     attrs: impl Iterator<Item = &'tcx T>,
     symbol: Symbol,
@@ -56,3 +56,32 @@ pub fn is_doc_alias_attrs_contain_symbol<'tcx, T: AttributeExt + 'tcx>(
     }
     false
 }
+
+/// Parse a single integer.
+///
+/// Used by attributes that take a single integer as argument, such as
+/// `#[link_ordinal]` and `#[rustc_layout_scalar_valid_range_start]`.
+/// `cx` is the context given to the attribute.
+/// `args` is the parser for the attribute arguments.
+pub(crate) fn parse_single_integer<S: Stage>(
+    cx: &mut AcceptContext<'_, '_, S>,
+    args: &ArgParser<'_>,
+) -> Option<u128> {
+    let Some(list) = args.list() else {
+        cx.expected_list(cx.attr_span);
+        return None;
+    };
+    let Some(single) = list.single() else {
+        cx.expected_single_argument(list.span);
+        return None;
+    };
+    let Some(lit) = single.lit() else {
+        cx.expected_integer_literal(single.span());
+        return None;
+    };
+    let LitKind::Int(num, _ty) = lit.kind else {
+        cx.expected_integer_literal(single.span());
+        return None;
+    };
+    Some(num.0)
+}
diff --git a/compiler/rustc_attr_parsing/src/context.rs b/compiler/rustc_attr_parsing/src/context.rs
index 1420753a44e..7f5b810f244 100644
--- a/compiler/rustc_attr_parsing/src/context.rs
+++ b/compiler/rustc_attr_parsing/src/context.rs
@@ -4,30 +4,33 @@ use std::ops::{Deref, DerefMut};
 use std::sync::LazyLock;
 
 use private::Sealed;
-use rustc_ast::{self as ast, LitKind, MetaItemLit, NodeId};
-use rustc_errors::{DiagCtxtHandle, Diagnostic};
-use rustc_feature::{AttributeTemplate, Features};
+use rustc_ast::{AttrStyle, CRATE_NODE_ID, MetaItemLit, NodeId};
+use rustc_errors::{Diag, Diagnostic, Level};
+use rustc_feature::{AttributeTemplate, AttributeType};
 use rustc_hir::attrs::AttributeKind;
 use rustc_hir::lints::{AttributeLint, AttributeLintKind};
-use rustc_hir::{AttrArgs, AttrItem, AttrPath, Attribute, HashIgnoredAttrId, HirId};
+use rustc_hir::{AttrPath, CRATE_HIR_ID, HirId};
 use rustc_session::Session;
-use rustc_span::{DUMMY_SP, ErrorGuaranteed, Span, Symbol, sym};
+use rustc_span::{ErrorGuaranteed, Span, Symbol};
 
+use crate::AttributeParser;
 use crate::attributes::allow_unstable::{
     AllowConstFnUnstableParser, AllowInternalUnstableParser, UnstableFeatureBoundParser,
 };
 use crate::attributes::body::CoroutineParser;
 use crate::attributes::codegen_attrs::{
-    ColdParser, CoverageParser, ExportNameParser, NakedParser, NoMangleParser, OptimizeParser,
-    TargetFeatureParser, TrackCallerParser, UsedParser,
+    ColdParser, CoverageParser, ExportNameParser, ForceTargetFeatureParser, NakedParser,
+    NoMangleParser, OptimizeParser, SanitizeParser, TargetFeatureParser, TrackCallerParser,
+    UsedParser,
 };
 use crate::attributes::confusables::ConfusablesParser;
+use crate::attributes::crate_level::CrateNameParser;
 use crate::attributes::deprecation::DeprecationParser;
 use crate::attributes::dummy::DummyParser;
 use crate::attributes::inline::{InlineParser, RustcForceInlineParser};
 use crate::attributes::link_attrs::{
     ExportStableParser, FfiConstParser, FfiPureParser, LinkNameParser, LinkOrdinalParser,
-    LinkSectionParser, StdInternalSymbolParser,
+    LinkParser, LinkSectionParser, LinkageParser, StdInternalSymbolParser,
 };
 use crate::attributes::lint_helpers::{
     AsPtrParser, AutomaticallyDerivedParser, PassByValueParser, PubTransparentParser,
@@ -43,6 +46,7 @@ use crate::attributes::path::PathParser as PathAttributeParser;
 use crate::attributes::proc_macro_attrs::{
     ProcMacroAttributeParser, ProcMacroDeriveParser, ProcMacroParser, RustcBuiltinMacroParser,
 };
+use crate::attributes::prototype::CustomMirParser;
 use crate::attributes::repr::{AlignParser, ReprParser};
 use crate::attributes::rustc_internal::{
     RustcLayoutScalarValidRangeEnd, RustcLayoutScalarValidRangeStart,
@@ -61,19 +65,22 @@ use crate::attributes::traits::{
 };
 use crate::attributes::transparency::TransparencyParser;
 use crate::attributes::{AttributeParser as _, Combine, Single, WithoutArgs};
-use crate::parser::{ArgParser, MetaItemParser, PathParser};
+use crate::parser::{ArgParser, PathParser};
 use crate::session_diagnostics::{AttributeParseError, AttributeParseErrorReason, UnknownMetaItem};
+use crate::target_checking::AllowedTargets;
 
 type GroupType<S> = LazyLock<GroupTypeInner<S>>;
 
-struct GroupTypeInner<S: Stage> {
-    accepters: BTreeMap<&'static [Symbol], Vec<GroupTypeInnerAccept<S>>>,
-    finalizers: Vec<FinalizeFn<S>>,
+pub(super) struct GroupTypeInner<S: Stage> {
+    pub(super) accepters: BTreeMap<&'static [Symbol], Vec<GroupTypeInnerAccept<S>>>,
+    pub(super) finalizers: Vec<FinalizeFn<S>>,
 }
 
-struct GroupTypeInnerAccept<S: Stage> {
-    template: AttributeTemplate,
-    accept_fn: AcceptFn<S>,
+pub(super) struct GroupTypeInnerAccept<S: Stage> {
+    pub(super) template: AttributeTemplate,
+    pub(super) accept_fn: AcceptFn<S>,
+    pub(super) allowed_targets: AllowedTargets,
+    pub(super) attribute_type: AttributeType,
 }
 
 type AcceptFn<S> =
@@ -121,7 +128,9 @@ macro_rules! attribute_parsers {
                                 STATE_OBJECT.with_borrow_mut(|s| {
                                     accept_fn(s, cx, args)
                                 })
-                            })
+                            }),
+                            allowed_targets: <$names as crate::attributes::AttributeParser<$stage>>::ALLOWED_TARGETS,
+                            attribute_type: <$names as crate::attributes::AttributeParser<$stage>>::TYPE,
                         });
                     }
 
@@ -152,6 +161,8 @@ attribute_parsers!(
         // tidy-alphabetical-start
         Combine<AllowConstFnUnstableParser>,
         Combine<AllowInternalUnstableParser>,
+        Combine<ForceTargetFeatureParser>,
+        Combine<LinkParser>,
         Combine<ReprParser>,
         Combine<TargetFeatureParser>,
         Combine<UnstableFeatureBoundParser>,
@@ -159,6 +170,8 @@ attribute_parsers!(
 
         // tidy-alphabetical-start
         Single<CoverageParser>,
+        Single<CrateNameParser>,
+        Single<CustomMirParser>,
         Single<DeprecationParser>,
         Single<DummyParser>,
         Single<ExportNameParser>,
@@ -167,6 +180,7 @@ attribute_parsers!(
         Single<LinkNameParser>,
         Single<LinkOrdinalParser>,
         Single<LinkSectionParser>,
+        Single<LinkageParser>,
         Single<MustUseParser>,
         Single<OptimizeParser>,
         Single<PathAttributeParser>,
@@ -176,6 +190,7 @@ attribute_parsers!(
         Single<RustcLayoutScalarValidRangeEnd>,
         Single<RustcLayoutScalarValidRangeStart>,
         Single<RustcObjectLifetimeDefaultParser>,
+        Single<SanitizeParser>,
         Single<ShouldPanicParser>,
         Single<SkipDuringMethodDispatchParser>,
         Single<TransparencyParser>,
@@ -238,6 +253,8 @@ pub trait Stage: Sized + 'static + Sealed {
     ) -> ErrorGuaranteed;
 
     fn should_emit(&self) -> ShouldEmit;
+
+    fn id_is_crate_root(id: Self::Id) -> bool;
 }
 
 // allow because it's a sealed trait
@@ -253,16 +270,16 @@ impl Stage for Early {
         sess: &'sess Session,
         diag: impl for<'x> Diagnostic<'x>,
     ) -> ErrorGuaranteed {
-        if self.emit_errors.should_emit() {
-            sess.dcx().emit_err(diag)
-        } else {
-            sess.dcx().create_err(diag).delay_as_bug()
-        }
+        self.should_emit().emit_err(sess.dcx().create_err(diag))
     }
 
     fn should_emit(&self) -> ShouldEmit {
         self.emit_errors
     }
+
+    fn id_is_crate_root(id: Self::Id) -> bool {
+        id == CRATE_NODE_ID
+    }
 }
 
 // allow because it's a sealed trait
@@ -284,6 +301,10 @@ impl Stage for Late {
     fn should_emit(&self) -> ShouldEmit {
         ShouldEmit::ErrorsAndLints
     }
+
+    fn id_is_crate_root(id: Self::Id) -> bool {
+        id == CRATE_HIR_ID
+    }
 }
 
 /// used when parsing attributes for miscellaneous things *before* ast lowering
@@ -304,6 +325,9 @@ pub struct AcceptContext<'f, 'sess, S: Stage> {
     /// The span of the attribute currently being parsed
     pub(crate) attr_span: Span,
 
+    /// Whether it is an inner or outer attribute
+    pub(crate) attr_style: AttrStyle,
+
     /// The expected structure of the attribute.
     ///
     /// Used in reporting errors to give a hint to users what the attribute *should* look like.
@@ -322,7 +346,7 @@ impl<'f, 'sess: 'f, S: Stage> SharedContext<'f, 'sess, S> {
     /// must be delayed until after HIR is built. This method will take care of the details of
     /// that.
     pub(crate) fn emit_lint(&mut self, lint: AttributeLintKind, span: Span) {
-        if !self.stage.should_emit().should_emit() {
+        if matches!(self.stage.should_emit(), ShouldEmit::Nothing) {
             return;
         }
         let id = self.target_id;
@@ -385,6 +409,7 @@ impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
                     i.kind.is_bytestr().then(|| self.sess().source_map().start_point(i.span))
                 }),
             },
+            attr_style: self.attr_style,
         })
     }
 
@@ -395,6 +420,7 @@ impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
             template: self.template.clone(),
             attribute: self.attr_path.clone(),
             reason: AttributeParseErrorReason::ExpectedIntegerLiteral,
+            attr_style: self.attr_style,
         })
     }
 
@@ -405,6 +431,7 @@ impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
             template: self.template.clone(),
             attribute: self.attr_path.clone(),
             reason: AttributeParseErrorReason::ExpectedList,
+            attr_style: self.attr_style,
         })
     }
 
@@ -415,6 +442,7 @@ impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
             template: self.template.clone(),
             attribute: self.attr_path.clone(),
             reason: AttributeParseErrorReason::ExpectedNoArgs,
+            attr_style: self.attr_style,
         })
     }
 
@@ -426,6 +454,7 @@ impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
             template: self.template.clone(),
             attribute: self.attr_path.clone(),
             reason: AttributeParseErrorReason::ExpectedIdentifier,
+            attr_style: self.attr_style,
         })
     }
 
@@ -438,6 +467,7 @@ impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
             template: self.template.clone(),
             attribute: self.attr_path.clone(),
             reason: AttributeParseErrorReason::ExpectedNameValue(name),
+            attr_style: self.attr_style,
         })
     }
 
@@ -449,6 +479,7 @@ impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
             template: self.template.clone(),
             attribute: self.attr_path.clone(),
             reason: AttributeParseErrorReason::DuplicateKey(key),
+            attr_style: self.attr_style,
         })
     }
 
@@ -461,6 +492,7 @@ impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
             template: self.template.clone(),
             attribute: self.attr_path.clone(),
             reason: AttributeParseErrorReason::UnexpectedLiteral,
+            attr_style: self.attr_style,
         })
     }
 
@@ -471,6 +503,7 @@ impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
             template: self.template.clone(),
             attribute: self.attr_path.clone(),
             reason: AttributeParseErrorReason::ExpectedSingleArgument,
+            attr_style: self.attr_style,
         })
     }
 
@@ -481,13 +514,15 @@ impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
             template: self.template.clone(),
             attribute: self.attr_path.clone(),
             reason: AttributeParseErrorReason::ExpectedAtLeastOneArgument,
+            attr_style: self.attr_style,
         })
     }
 
+    /// produces an error along the lines of `expected one of [foo, meow]`
     pub(crate) fn expected_specific_argument(
         &self,
         span: Span,
-        possibilities: Vec<&'static str>,
+        possibilities: &[Symbol],
     ) -> ErrorGuaranteed {
         self.emit_err(AttributeParseError {
             span,
@@ -499,13 +534,16 @@ impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
                 strings: false,
                 list: false,
             },
+            attr_style: self.attr_style,
         })
     }
 
+    /// produces an error along the lines of `expected one of [foo, meow] as an argument`.
+    /// i.e. slightly different wording to [`expected_specific_argument`](Self::expected_specific_argument).
     pub(crate) fn expected_specific_argument_and_list(
         &self,
         span: Span,
-        possibilities: Vec<&'static str>,
+        possibilities: &[Symbol],
     ) -> ErrorGuaranteed {
         self.emit_err(AttributeParseError {
             span,
@@ -517,13 +555,15 @@ impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
                 strings: false,
                 list: true,
             },
+            attr_style: self.attr_style,
         })
     }
 
+    /// produces an error along the lines of `expected one of ["foo", "meow"]`
     pub(crate) fn expected_specific_argument_strings(
         &self,
         span: Span,
-        possibilities: Vec<&'static str>,
+        possibilities: &[Symbol],
     ) -> ErrorGuaranteed {
         self.emit_err(AttributeParseError {
             span,
@@ -535,6 +575,7 @@ impl<'f, 'sess: 'f, S: Stage> AcceptContext<'f, 'sess, S> {
                 strings: true,
                 list: false,
             },
+            attr_style: self.attr_style,
         })
     }
 
@@ -570,7 +611,7 @@ pub struct SharedContext<'p, 'sess, S: Stage> {
     /// The id ([`NodeId`] if `S` is `Early`, [`HirId`] if `S` is `Late`) of the syntactical component this attribute was applied to
     pub(crate) target_id: S::Id,
 
-    emit_lint: &'p mut dyn FnMut(AttributeLint<S::Id>),
+    pub(crate) emit_lint: &'p mut dyn FnMut(AttributeLint<S::Id>),
 }
 
 /// Context given to every attribute parser during finalization.
@@ -623,8 +664,13 @@ pub enum OmitDoc {
     Skip,
 }
 
-#[derive(Copy, Clone)]
+#[derive(Copy, Clone, Debug)]
 pub enum ShouldEmit {
+    /// The operations will emit errors, and lints, and errors are fatal.
+    ///
+    /// Only relevant when early parsing, in late parsing equivalent to `ErrorsAndLints`.
+    /// Late parsing is never fatal, and instead tries to emit as many diagnostics as possible.
+    EarlyFatal,
     /// The operation will emit errors and lints.
     /// This is usually what you need.
     ErrorsAndLints,
@@ -634,332 +680,12 @@ pub enum ShouldEmit {
 }
 
 impl ShouldEmit {
-    pub fn should_emit(&self) -> bool {
+    pub(crate) fn emit_err(&self, diag: Diag<'_>) -> ErrorGuaranteed {
         match self {
-            ShouldEmit::ErrorsAndLints => true,
-            ShouldEmit::Nothing => false,
-        }
-    }
-}
-
-/// Context created once, for example as part of the ast lowering
-/// context, through which all attributes can be lowered.
-pub struct AttributeParser<'sess, S: Stage = Late> {
-    pub(crate) tools: Vec<Symbol>,
-    features: Option<&'sess Features>,
-    sess: &'sess Session,
-    stage: S,
-
-    /// *Only* parse attributes with this symbol.
-    ///
-    /// Used in cases where we want the lowering infrastructure for parse just a single attribute.
-    parse_only: Option<Symbol>,
-}
-
-impl<'sess> AttributeParser<'sess, Early> {
-    /// This method allows you to parse attributes *before* you have access to features or tools.
-    /// One example where this is necessary, is to parse `feature` attributes themselves for
-    /// example.
-    ///
-    /// Try to use this as little as possible. Attributes *should* be lowered during
-    /// `rustc_ast_lowering`. Some attributes require access to features to parse, which would
-    /// crash if you tried to do so through [`parse_limited`](Self::parse_limited).
-    ///
-    /// To make sure use is limited, supply a `Symbol` you'd like to parse. Only attributes with
-    /// that symbol are picked out of the list of instructions and parsed. Those are returned.
-    ///
-    /// No diagnostics will be emitted when parsing limited. Lints are not emitted at all, while
-    /// errors will be emitted as a delayed bugs. in other words, we *expect* attributes parsed
-    /// with `parse_limited` to be reparsed later during ast lowering where we *do* emit the errors
-    pub fn parse_limited(
-        sess: &'sess Session,
-        attrs: &[ast::Attribute],
-        sym: Symbol,
-        target_span: Span,
-        target_node_id: NodeId,
-        features: Option<&'sess Features>,
-    ) -> Option<Attribute> {
-        let mut p = Self {
-            features,
-            tools: Vec::new(),
-            parse_only: Some(sym),
-            sess,
-            stage: Early { emit_errors: ShouldEmit::Nothing },
-        };
-        let mut parsed = p.parse_attribute_list(
-            attrs,
-            target_span,
-            target_node_id,
-            OmitDoc::Skip,
-            std::convert::identity,
-            |_lint| {
-                panic!("can't emit lints here for now (nothing uses this atm)");
-            },
-        );
-        assert!(parsed.len() <= 1);
-
-        parsed.pop()
-    }
-
-    pub fn parse_single<T>(
-        sess: &'sess Session,
-        attr: &ast::Attribute,
-        target_span: Span,
-        target_node_id: NodeId,
-        features: Option<&'sess Features>,
-        emit_errors: ShouldEmit,
-        parse_fn: fn(cx: &mut AcceptContext<'_, '_, Early>, item: &ArgParser<'_>) -> T,
-        template: &AttributeTemplate,
-    ) -> T {
-        let mut parser = Self {
-            features,
-            tools: Vec::new(),
-            parse_only: None,
-            sess,
-            stage: Early { emit_errors },
-        };
-        let ast::AttrKind::Normal(normal_attr) = &attr.kind else {
-            panic!("parse_single called on a doc attr")
-        };
-        let meta_parser = MetaItemParser::from_attr(normal_attr, parser.dcx());
-        let path = meta_parser.path();
-        let args = meta_parser.args();
-        let mut cx: AcceptContext<'_, 'sess, Early> = AcceptContext {
-            shared: SharedContext {
-                cx: &mut parser,
-                target_span,
-                target_id: target_node_id,
-                emit_lint: &mut |_lint| {
-                    panic!("can't emit lints here for now (nothing uses this atm)");
-                },
-            },
-            attr_span: attr.span,
-            template,
-            attr_path: path.get_attribute_path(),
-        };
-        parse_fn(&mut cx, args)
-    }
-}
-
-impl<'sess, S: Stage> AttributeParser<'sess, S> {
-    pub fn new(
-        sess: &'sess Session,
-        features: &'sess Features,
-        tools: Vec<Symbol>,
-        stage: S,
-    ) -> Self {
-        Self { features: Some(features), tools, parse_only: None, sess, stage }
-    }
-
-    pub(crate) fn sess(&self) -> &'sess Session {
-        &self.sess
-    }
-
-    pub(crate) fn features(&self) -> &'sess Features {
-        self.features.expect("features not available at this point in the compiler")
-    }
-
-    pub(crate) fn features_option(&self) -> Option<&'sess Features> {
-        self.features
-    }
-
-    pub(crate) fn dcx(&self) -> DiagCtxtHandle<'sess> {
-        self.sess().dcx()
-    }
-
-    /// Parse a list of attributes.
-    ///
-    /// `target_span` is the span of the thing this list of attributes is applied to,
-    /// and when `omit_doc` is set, doc attributes are filtered out.
-    pub fn parse_attribute_list(
-        &mut self,
-        attrs: &[ast::Attribute],
-        target_span: Span,
-        target_id: S::Id,
-        omit_doc: OmitDoc,
-
-        lower_span: impl Copy + Fn(Span) -> Span,
-        mut emit_lint: impl FnMut(AttributeLint<S::Id>),
-    ) -> Vec<Attribute> {
-        let mut attributes = Vec::new();
-        let mut attr_paths = Vec::new();
-
-        for attr in attrs {
-            // If we're only looking for a single attribute, skip all the ones we don't care about.
-            if let Some(expected) = self.parse_only {
-                if !attr.has_name(expected) {
-                    continue;
-                }
-            }
-
-            // Sometimes, for example for `#![doc = include_str!("readme.md")]`,
-            // doc still contains a non-literal. You might say, when we're lowering attributes
-            // that's expanded right? But no, sometimes, when parsing attributes on macros,
-            // we already use the lowering logic and these are still there. So, when `omit_doc`
-            // is set we *also* want to ignore these.
-            if omit_doc == OmitDoc::Skip && attr.has_name(sym::doc) {
-                continue;
-            }
-
-            match &attr.kind {
-                ast::AttrKind::DocComment(comment_kind, symbol) => {
-                    if omit_doc == OmitDoc::Skip {
-                        continue;
-                    }
-
-                    attributes.push(Attribute::Parsed(AttributeKind::DocComment {
-                        style: attr.style,
-                        kind: *comment_kind,
-                        span: lower_span(attr.span),
-                        comment: *symbol,
-                    }))
-                }
-                // // FIXME: make doc attributes go through a proper attribute parser
-                // ast::AttrKind::Normal(n) if n.has_name(sym::doc) => {
-                //     let p = GenericMetaItemParser::from_attr(&n, self.dcx());
-                //
-                //     attributes.push(Attribute::Parsed(AttributeKind::DocComment {
-                //         style: attr.style,
-                //         kind: CommentKind::Line,
-                //         span: attr.span,
-                //         comment: p.args().name_value(),
-                //     }))
-                // }
-                ast::AttrKind::Normal(n) => {
-                    attr_paths.push(PathParser::Ast(&n.item.path));
-
-                    let parser = MetaItemParser::from_attr(n, self.dcx());
-                    let path = parser.path();
-                    let args = parser.args();
-                    let parts = path.segments().map(|i| i.name).collect::<Vec<_>>();
-
-                    if let Some(accepts) = S::parsers().accepters.get(parts.as_slice()) {
-                        for accept in accepts {
-                            let mut cx: AcceptContext<'_, 'sess, S> = AcceptContext {
-                                shared: SharedContext {
-                                    cx: self,
-                                    target_span,
-                                    target_id,
-                                    emit_lint: &mut emit_lint,
-                                },
-                                attr_span: lower_span(attr.span),
-                                template: &accept.template,
-                                attr_path: path.get_attribute_path(),
-                            };
-
-                            (accept.accept_fn)(&mut cx, args)
-                        }
-                    } else {
-                        // If we're here, we must be compiling a tool attribute... Or someone
-                        // forgot to parse their fancy new attribute. Let's warn them in any case.
-                        // If you are that person, and you really think your attribute should
-                        // remain unparsed, carefully read the documentation in this module and if
-                        // you still think so you can add an exception to this assertion.
-
-                        // FIXME(jdonszelmann): convert other attributes, and check with this that
-                        // we caught em all
-                        // const FIXME_TEMPORARY_ATTR_ALLOWLIST: &[Symbol] = &[sym::cfg];
-                        // assert!(
-                        //     self.tools.contains(&parts[0]) || true,
-                        //     // || FIXME_TEMPORARY_ATTR_ALLOWLIST.contains(&parts[0]),
-                        //     "attribute {path} wasn't parsed and isn't a know tool attribute",
-                        // );
-
-                        attributes.push(Attribute::Unparsed(Box::new(AttrItem {
-                            path: AttrPath::from_ast(&n.item.path),
-                            args: self.lower_attr_args(&n.item.args, lower_span),
-                            id: HashIgnoredAttrId { attr_id: attr.id },
-                            style: attr.style,
-                            span: lower_span(attr.span),
-                        })));
-                    }
-                }
-            }
-        }
-
-        let mut parsed_attributes = Vec::new();
-        for f in &S::parsers().finalizers {
-            if let Some(attr) = f(&mut FinalizeContext {
-                shared: SharedContext {
-                    cx: self,
-                    target_span,
-                    target_id,
-                    emit_lint: &mut emit_lint,
-                },
-                all_attrs: &attr_paths,
-            }) {
-                parsed_attributes.push(Attribute::Parsed(attr));
-            }
-        }
-
-        attributes.extend(parsed_attributes);
-
-        attributes
-    }
-
-    /// Returns whether there is a parser for an attribute with this name
-    pub fn is_parsed_attribute(path: &[Symbol]) -> bool {
-        Late::parsers().accepters.contains_key(path)
-    }
-
-    fn lower_attr_args(&self, args: &ast::AttrArgs, lower_span: impl Fn(Span) -> Span) -> AttrArgs {
-        match args {
-            ast::AttrArgs::Empty => AttrArgs::Empty,
-            ast::AttrArgs::Delimited(args) => AttrArgs::Delimited(args.clone()),
-            // This is an inert key-value attribute - it will never be visible to macros
-            // after it gets lowered to HIR. Therefore, we can extract literals to handle
-            // nonterminals in `#[doc]` (e.g. `#[doc = $e]`).
-            ast::AttrArgs::Eq { eq_span, expr } => {
-                // In valid code the value always ends up as a single literal. Otherwise, a dummy
-                // literal suffices because the error is handled elsewhere.
-                let lit = if let ast::ExprKind::Lit(token_lit) = expr.kind
-                    && let Ok(lit) =
-                        ast::MetaItemLit::from_token_lit(token_lit, lower_span(expr.span))
-                {
-                    lit
-                } else {
-                    let guar = self.dcx().span_delayed_bug(
-                        args.span().unwrap_or(DUMMY_SP),
-                        "expr in place where literal is expected (builtin attr parsing)",
-                    );
-                    ast::MetaItemLit {
-                        symbol: sym::dummy,
-                        suffix: None,
-                        kind: ast::LitKind::Err(guar),
-                        span: DUMMY_SP,
-                    }
-                };
-                AttrArgs::Eq { eq_span: lower_span(*eq_span), expr: lit }
-            }
+            ShouldEmit::EarlyFatal if diag.level() == Level::DelayedBug => diag.emit(),
+            ShouldEmit::EarlyFatal => diag.upgrade_to_fatal().emit(),
+            ShouldEmit::ErrorsAndLints => diag.emit(),
+            ShouldEmit::Nothing => diag.delay_as_bug(),
         }
     }
 }
-
-/// Parse a single integer.
-///
-/// Used by attributes that take a single integer as argument, such as
-/// `#[link_ordinal]` and `#[rustc_layout_scalar_valid_range_start]`.
-/// `cx` is the context given to the attribute.
-/// `args` is the parser for the attribute arguments.
-pub(crate) fn parse_single_integer<S: Stage>(
-    cx: &mut AcceptContext<'_, '_, S>,
-    args: &ArgParser<'_>,
-) -> Option<u128> {
-    let Some(list) = args.list() else {
-        cx.expected_list(cx.attr_span);
-        return None;
-    };
-    let Some(single) = list.single() else {
-        cx.expected_single_argument(list.span);
-        return None;
-    };
-    let Some(lit) = single.lit() else {
-        cx.expected_integer_literal(single.span());
-        return None;
-    };
-    let LitKind::Int(num, _ty) = lit.kind else {
-        cx.expected_integer_literal(single.span());
-        return None;
-    };
-    Some(num.0)
-}
diff --git a/compiler/rustc_attr_parsing/src/interface.rs b/compiler/rustc_attr_parsing/src/interface.rs
new file mode 100644
index 00000000000..0fe3c209421
--- /dev/null
+++ b/compiler/rustc_attr_parsing/src/interface.rs
@@ -0,0 +1,363 @@
+use std::borrow::Cow;
+
+use rustc_ast as ast;
+use rustc_ast::NodeId;
+use rustc_errors::DiagCtxtHandle;
+use rustc_feature::{AttributeTemplate, Features};
+use rustc_hir::attrs::AttributeKind;
+use rustc_hir::lints::AttributeLint;
+use rustc_hir::{AttrArgs, AttrItem, AttrPath, Attribute, HashIgnoredAttrId, Target};
+use rustc_session::Session;
+use rustc_span::{DUMMY_SP, Span, Symbol, sym};
+
+use crate::context::{AcceptContext, FinalizeContext, SharedContext, Stage};
+use crate::parser::{ArgParser, MetaItemParser, PathParser};
+use crate::{Early, Late, OmitDoc, ShouldEmit};
+
+/// Context created once, for example as part of the ast lowering
+/// context, through which all attributes can be lowered.
+pub struct AttributeParser<'sess, S: Stage = Late> {
+    pub(crate) tools: Vec<Symbol>,
+    pub(crate) features: Option<&'sess Features>,
+    pub(crate) sess: &'sess Session,
+    pub(crate) stage: S,
+
+    /// *Only* parse attributes with this symbol.
+    ///
+    /// Used in cases where we want the lowering infrastructure for parse just a single attribute.
+    parse_only: Option<Symbol>,
+}
+
+impl<'sess> AttributeParser<'sess, Early> {
+    /// This method allows you to parse attributes *before* you have access to features or tools.
+    /// One example where this is necessary, is to parse `feature` attributes themselves for
+    /// example.
+    ///
+    /// Try to use this as little as possible. Attributes *should* be lowered during
+    /// `rustc_ast_lowering`. Some attributes require access to features to parse, which would
+    /// crash if you tried to do so through [`parse_limited`](Self::parse_limited).
+    ///
+    /// To make sure use is limited, supply a `Symbol` you'd like to parse. Only attributes with
+    /// that symbol are picked out of the list of instructions and parsed. Those are returned.
+    ///
+    /// No diagnostics will be emitted when parsing limited. Lints are not emitted at all, while
+    /// errors will be emitted as a delayed bugs. in other words, we *expect* attributes parsed
+    /// with `parse_limited` to be reparsed later during ast lowering where we *do* emit the errors
+    pub fn parse_limited(
+        sess: &'sess Session,
+        attrs: &[ast::Attribute],
+        sym: Symbol,
+        target_span: Span,
+        target_node_id: NodeId,
+        features: Option<&'sess Features>,
+    ) -> Option<Attribute> {
+        Self::parse_limited_should_emit(
+            sess,
+            attrs,
+            sym,
+            target_span,
+            target_node_id,
+            features,
+            ShouldEmit::Nothing,
+        )
+    }
+
+    /// Usually you want `parse_limited`, which defaults to no errors.
+    pub fn parse_limited_should_emit(
+        sess: &'sess Session,
+        attrs: &[ast::Attribute],
+        sym: Symbol,
+        target_span: Span,
+        target_node_id: NodeId,
+        features: Option<&'sess Features>,
+        should_emit: ShouldEmit,
+    ) -> Option<Attribute> {
+        let mut parsed = Self::parse_limited_all(
+            sess,
+            attrs,
+            Some(sym),
+            Target::Crate, // Does not matter, we're not going to emit errors anyways
+            target_span,
+            target_node_id,
+            features,
+            should_emit,
+        );
+        assert!(parsed.len() <= 1);
+        parsed.pop()
+    }
+
+    pub fn parse_limited_all(
+        sess: &'sess Session,
+        attrs: &[ast::Attribute],
+        parse_only: Option<Symbol>,
+        target: Target,
+        target_span: Span,
+        target_node_id: NodeId,
+        features: Option<&'sess Features>,
+        emit_errors: ShouldEmit,
+    ) -> Vec<Attribute> {
+        let mut p =
+            Self { features, tools: Vec::new(), parse_only, sess, stage: Early { emit_errors } };
+        p.parse_attribute_list(
+            attrs,
+            target_span,
+            target_node_id,
+            target,
+            OmitDoc::Skip,
+            std::convert::identity,
+            |lint| {
+                crate::lints::emit_attribute_lint(&lint, sess);
+            },
+        )
+    }
+
+    pub fn parse_single<T>(
+        sess: &'sess Session,
+        attr: &ast::Attribute,
+        target_span: Span,
+        target_node_id: NodeId,
+        features: Option<&'sess Features>,
+        emit_errors: ShouldEmit,
+        parse_fn: fn(cx: &mut AcceptContext<'_, '_, Early>, item: &ArgParser<'_>) -> Option<T>,
+        template: &AttributeTemplate,
+    ) -> Option<T> {
+        let mut parser = Self {
+            features,
+            tools: Vec::new(),
+            parse_only: None,
+            sess,
+            stage: Early { emit_errors },
+        };
+        let ast::AttrKind::Normal(normal_attr) = &attr.kind else {
+            panic!("parse_single called on a doc attr")
+        };
+        let parts =
+            normal_attr.item.path.segments.iter().map(|seg| seg.ident.name).collect::<Vec<_>>();
+        let meta_parser = MetaItemParser::from_attr(normal_attr, &parts, &sess.psess, emit_errors)?;
+        let path = meta_parser.path();
+        let args = meta_parser.args();
+        let mut cx: AcceptContext<'_, 'sess, Early> = AcceptContext {
+            shared: SharedContext {
+                cx: &mut parser,
+                target_span,
+                target_id: target_node_id,
+                emit_lint: &mut |lint| {
+                    crate::lints::emit_attribute_lint(&lint, sess);
+                },
+            },
+            attr_span: attr.span,
+            attr_style: attr.style,
+            template,
+            attr_path: path.get_attribute_path(),
+        };
+        parse_fn(&mut cx, args)
+    }
+}
+
+impl<'sess, S: Stage> AttributeParser<'sess, S> {
+    pub fn new(
+        sess: &'sess Session,
+        features: &'sess Features,
+        tools: Vec<Symbol>,
+        stage: S,
+    ) -> Self {
+        Self { features: Some(features), tools, parse_only: None, sess, stage }
+    }
+
+    pub(crate) fn sess(&self) -> &'sess Session {
+        &self.sess
+    }
+
+    pub(crate) fn features(&self) -> &'sess Features {
+        self.features.expect("features not available at this point in the compiler")
+    }
+
+    pub(crate) fn features_option(&self) -> Option<&'sess Features> {
+        self.features
+    }
+
+    pub(crate) fn dcx(&self) -> DiagCtxtHandle<'sess> {
+        self.sess().dcx()
+    }
+
+    /// Parse a list of attributes.
+    ///
+    /// `target_span` is the span of the thing this list of attributes is applied to,
+    /// and when `omit_doc` is set, doc attributes are filtered out.
+    pub fn parse_attribute_list(
+        &mut self,
+        attrs: &[ast::Attribute],
+        target_span: Span,
+        target_id: S::Id,
+        target: Target,
+        omit_doc: OmitDoc,
+
+        lower_span: impl Copy + Fn(Span) -> Span,
+        mut emit_lint: impl FnMut(AttributeLint<S::Id>),
+    ) -> Vec<Attribute> {
+        let mut attributes = Vec::new();
+        let mut attr_paths = Vec::new();
+
+        for attr in attrs {
+            // If we're only looking for a single attribute, skip all the ones we don't care about.
+            if let Some(expected) = self.parse_only {
+                if !attr.has_name(expected) {
+                    continue;
+                }
+            }
+
+            // Sometimes, for example for `#![doc = include_str!("readme.md")]`,
+            // doc still contains a non-literal. You might say, when we're lowering attributes
+            // that's expanded right? But no, sometimes, when parsing attributes on macros,
+            // we already use the lowering logic and these are still there. So, when `omit_doc`
+            // is set we *also* want to ignore these.
+            if omit_doc == OmitDoc::Skip && attr.has_name(sym::doc) {
+                continue;
+            }
+
+            match &attr.kind {
+                ast::AttrKind::DocComment(comment_kind, symbol) => {
+                    if omit_doc == OmitDoc::Skip {
+                        continue;
+                    }
+
+                    attributes.push(Attribute::Parsed(AttributeKind::DocComment {
+                        style: attr.style,
+                        kind: *comment_kind,
+                        span: lower_span(attr.span),
+                        comment: *symbol,
+                    }))
+                }
+                // // FIXME: make doc attributes go through a proper attribute parser
+                // ast::AttrKind::Normal(n) if n.has_name(sym::doc) => {
+                //     let p = GenericMetaItemParser::from_attr(&n, self.dcx());
+                //
+                //     attributes.push(Attribute::Parsed(AttributeKind::DocComment {
+                //         style: attr.style,
+                //         kind: CommentKind::Line,
+                //         span: attr.span,
+                //         comment: p.args().name_value(),
+                //     }))
+                // }
+                ast::AttrKind::Normal(n) => {
+                    attr_paths.push(PathParser(Cow::Borrowed(&n.item.path)));
+
+                    let parts =
+                        n.item.path.segments.iter().map(|seg| seg.ident.name).collect::<Vec<_>>();
+
+                    if let Some(accepts) = S::parsers().accepters.get(parts.as_slice()) {
+                        let Some(parser) = MetaItemParser::from_attr(
+                            n,
+                            &parts,
+                            &self.sess.psess,
+                            self.stage.should_emit(),
+                        ) else {
+                            continue;
+                        };
+                        let path = parser.path();
+                        let args = parser.args();
+                        for accept in accepts {
+                            let mut cx: AcceptContext<'_, 'sess, S> = AcceptContext {
+                                shared: SharedContext {
+                                    cx: self,
+                                    target_span,
+                                    target_id,
+                                    emit_lint: &mut emit_lint,
+                                },
+                                attr_span: lower_span(attr.span),
+                                attr_style: attr.style,
+                                template: &accept.template,
+                                attr_path: path.get_attribute_path(),
+                            };
+
+                            (accept.accept_fn)(&mut cx, args);
+                            if !matches!(cx.stage.should_emit(), ShouldEmit::Nothing) {
+                                Self::check_type(accept.attribute_type, target, &mut cx);
+                                Self::check_target(&accept.allowed_targets, target, &mut cx);
+                            }
+                        }
+                    } else {
+                        // If we're here, we must be compiling a tool attribute... Or someone
+                        // forgot to parse their fancy new attribute. Let's warn them in any case.
+                        // If you are that person, and you really think your attribute should
+                        // remain unparsed, carefully read the documentation in this module and if
+                        // you still think so you can add an exception to this assertion.
+
+                        // FIXME(jdonszelmann): convert other attributes, and check with this that
+                        // we caught em all
+                        // const FIXME_TEMPORARY_ATTR_ALLOWLIST: &[Symbol] = &[sym::cfg];
+                        // assert!(
+                        //     self.tools.contains(&parts[0]) || true,
+                        //     // || FIXME_TEMPORARY_ATTR_ALLOWLIST.contains(&parts[0]),
+                        //     "attribute {path} wasn't parsed and isn't a know tool attribute",
+                        // );
+
+                        attributes.push(Attribute::Unparsed(Box::new(AttrItem {
+                            path: AttrPath::from_ast(&n.item.path),
+                            args: self.lower_attr_args(&n.item.args, lower_span),
+                            id: HashIgnoredAttrId { attr_id: attr.id },
+                            style: attr.style,
+                            span: lower_span(attr.span),
+                        })));
+                    }
+                }
+            }
+        }
+
+        let mut parsed_attributes = Vec::new();
+        for f in &S::parsers().finalizers {
+            if let Some(attr) = f(&mut FinalizeContext {
+                shared: SharedContext {
+                    cx: self,
+                    target_span,
+                    target_id,
+                    emit_lint: &mut emit_lint,
+                },
+                all_attrs: &attr_paths,
+            }) {
+                parsed_attributes.push(Attribute::Parsed(attr));
+            }
+        }
+
+        attributes.extend(parsed_attributes);
+
+        attributes
+    }
+
+    /// Returns whether there is a parser for an attribute with this name
+    pub fn is_parsed_attribute(path: &[Symbol]) -> bool {
+        Late::parsers().accepters.contains_key(path)
+    }
+
+    fn lower_attr_args(&self, args: &ast::AttrArgs, lower_span: impl Fn(Span) -> Span) -> AttrArgs {
+        match args {
+            ast::AttrArgs::Empty => AttrArgs::Empty,
+            ast::AttrArgs::Delimited(args) => AttrArgs::Delimited(args.clone()),
+            // This is an inert key-value attribute - it will never be visible to macros
+            // after it gets lowered to HIR. Therefore, we can extract literals to handle
+            // nonterminals in `#[doc]` (e.g. `#[doc = $e]`).
+            ast::AttrArgs::Eq { eq_span, expr } => {
+                // In valid code the value always ends up as a single literal. Otherwise, a dummy
+                // literal suffices because the error is handled elsewhere.
+                let lit = if let ast::ExprKind::Lit(token_lit) = expr.kind
+                    && let Ok(lit) =
+                        ast::MetaItemLit::from_token_lit(token_lit, lower_span(expr.span))
+                {
+                    lit
+                } else {
+                    let guar = self.dcx().span_delayed_bug(
+                        args.span().unwrap_or(DUMMY_SP),
+                        "expr in place where literal is expected (builtin attr parsing)",
+                    );
+                    ast::MetaItemLit {
+                        symbol: sym::dummy,
+                        suffix: None,
+                        kind: ast::LitKind::Err(guar),
+                        span: DUMMY_SP,
+                    }
+                };
+                AttrArgs::Eq { eq_span: lower_span(*eq_span), expr: lit }
+            }
+        }
+    }
+}
diff --git a/compiler/rustc_attr_parsing/src/lib.rs b/compiler/rustc_attr_parsing/src/lib.rs
index fc1377e5314..f51cc8c4e8b 100644
--- a/compiler/rustc_attr_parsing/src/lib.rs
+++ b/compiler/rustc_attr_parsing/src/lib.rs
@@ -79,23 +79,37 @@
 // tidy-alphabetical-start
 #![allow(internal_features)]
 #![doc(rust_logo)]
+#![feature(decl_macro)]
 #![feature(rustdoc_internals)]
 #![recursion_limit = "256"]
 // tidy-alphabetical-end
 
 #[macro_use]
+/// All the individual attribute parsers for each of rustc's built-in attributes.
 mod attributes;
+
+/// All the important types given to attribute parsers when parsing
 pub(crate) mod context;
-mod lints;
+
+/// Code that other crates interact with, to actually parse a list (or sometimes single)
+/// attribute.
+mod interface;
+
+/// Despite this entire module called attribute parsing and the term being a little overloaded,
+/// in this module the code lives that actually breaks up tokenstreams into semantic pieces of attributes,
+/// like lists or name-value pairs.
 pub mod parser;
+
+mod lints;
 mod session_diagnostics;
+mod target_checking;
+pub mod validate_attr;
 
 pub use attributes::cfg::{CFG_TEMPLATE, EvalConfigResult, eval_config_entry, parse_cfg_attr};
 pub use attributes::cfg_old::*;
-pub use attributes::util::{
-    find_crate_name, is_builtin_attr, is_doc_alias_attrs_contain_symbol, parse_version,
-};
-pub use context::{AttributeParser, Early, Late, OmitDoc, ShouldEmit};
+pub use attributes::util::{is_builtin_attr, is_doc_alias_attrs_contain_symbol, parse_version};
+pub use context::{Early, Late, OmitDoc, ShouldEmit};
+pub use interface::AttributeParser;
 pub use lints::emit_attribute_lint;
 
 rustc_fluent_macro::fluent_messages! { "../messages.ftl" }
diff --git a/compiler/rustc_attr_parsing/src/lints.rs b/compiler/rustc_attr_parsing/src/lints.rs
index 22f5531bc80..b1a971eec32 100644
--- a/compiler/rustc_attr_parsing/src/lints.rs
+++ b/compiler/rustc_attr_parsing/src/lints.rs
@@ -1,10 +1,13 @@
+use std::borrow::Cow;
+
 use rustc_errors::{DiagArgValue, LintEmitter};
-use rustc_hir::HirId;
+use rustc_hir::Target;
 use rustc_hir::lints::{AttributeLint, AttributeLintKind};
+use rustc_span::sym;
 
 use crate::session_diagnostics;
 
-pub fn emit_attribute_lint<L: LintEmitter>(lint: &AttributeLint<HirId>, lint_emitter: L) {
+pub fn emit_attribute_lint<L: LintEmitter>(lint: &AttributeLint<L::Id>, lint_emitter: L) {
     let AttributeLint { id, span, kind } = lint;
 
     match kind {
@@ -34,5 +37,48 @@ pub fn emit_attribute_lint<L: LintEmitter>(lint: &AttributeLint<HirId>, lint_emi
             *first_span,
             session_diagnostics::EmptyAttributeList { attr_span: *first_span },
         ),
+        AttributeLintKind::InvalidTarget { name, target, applied, only } => lint_emitter
+            .emit_node_span_lint(
+                // This check is here because `deprecated` had its own lint group and removing this would be a breaking change
+                if name.segments[0].name == sym::deprecated
+                    && ![
+                        Target::Closure,
+                        Target::Expression,
+                        Target::Statement,
+                        Target::Arm,
+                        Target::MacroCall,
+                    ]
+                    .contains(target)
+                {
+                    rustc_session::lint::builtin::USELESS_DEPRECATED
+                } else {
+                    rustc_session::lint::builtin::UNUSED_ATTRIBUTES
+                },
+                *id,
+                *span,
+                session_diagnostics::InvalidTargetLint {
+                    name: name.clone(),
+                    target: target.plural_name(),
+                    applied: DiagArgValue::StrListSepByAnd(
+                        applied.into_iter().map(|i| Cow::Owned(i.to_string())).collect(),
+                    ),
+                    only,
+                    attr_span: *span,
+                },
+            ),
+
+        &AttributeLintKind::InvalidStyle { ref name, is_used_as_inner, target, target_span } => {
+            lint_emitter.emit_node_span_lint(
+                rustc_session::lint::builtin::UNUSED_ATTRIBUTES,
+                *id,
+                *span,
+                session_diagnostics::InvalidAttrStyle {
+                    name: name.clone(),
+                    is_used_as_inner,
+                    target_span: (!is_used_as_inner).then_some(target_span),
+                    target,
+                },
+            )
+        }
     }
 }
diff --git a/compiler/rustc_attr_parsing/src/parser.rs b/compiler/rustc_attr_parsing/src/parser.rs
index aecaae947c9..6d3cf684296 100644
--- a/compiler/rustc_attr_parsing/src/parser.rs
+++ b/compiler/rustc_attr_parsing/src/parser.rs
@@ -3,45 +3,30 @@
 //!
 //! FIXME(jdonszelmann): delete `rustc_ast/attr/mod.rs`
 
+use std::borrow::Cow;
 use std::fmt::{Debug, Display};
-use std::iter::Peekable;
 
-use rustc_ast::token::{self, Delimiter, Token};
-use rustc_ast::tokenstream::{TokenStreamIter, TokenTree};
+use rustc_ast::token::{self, Delimiter, MetaVarKind};
+use rustc_ast::tokenstream::TokenStream;
 use rustc_ast::{AttrArgs, DelimArgs, Expr, ExprKind, LitKind, MetaItemLit, NormalAttr, Path};
 use rustc_ast_pretty::pprust;
-use rustc_errors::DiagCtxtHandle;
+use rustc_errors::PResult;
 use rustc_hir::{self as hir, AttrPath};
-use rustc_span::{ErrorGuaranteed, Ident, Span, Symbol, kw, sym};
-
-pub struct SegmentIterator<'a> {
-    offset: usize,
-    path: &'a PathParser<'a>,
-}
-
-impl<'a> Iterator for SegmentIterator<'a> {
-    type Item = &'a Ident;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        if self.offset >= self.path.len() {
-            return None;
-        }
-
-        let res = match self.path {
-            PathParser::Ast(ast_path) => &ast_path.segments[self.offset].ident,
-            PathParser::Attr(attr_path) => &attr_path.segments[self.offset],
-        };
-
-        self.offset += 1;
-        Some(res)
-    }
-}
+use rustc_parse::exp;
+use rustc_parse::parser::{Parser, PathStyle, token_descr};
+use rustc_session::errors::report_lit_error;
+use rustc_session::parse::ParseSess;
+use rustc_span::{ErrorGuaranteed, Ident, Span, Symbol, sym};
+use thin_vec::ThinVec;
+
+use crate::ShouldEmit;
+use crate::session_diagnostics::{
+    InvalidMetaItem, InvalidMetaItemQuoteIdentSugg, InvalidMetaItemRemoveNegSugg, MetaBadDelim,
+    MetaBadDelimSugg, SuffixedLiteralInAttribute,
+};
 
 #[derive(Clone, Debug)]
-pub enum PathParser<'a> {
-    Ast(&'a Path),
-    Attr(AttrPath),
-}
+pub struct PathParser<'a>(pub Cow<'a, Path>);
 
 impl<'a> PathParser<'a> {
     pub fn get_attribute_path(&self) -> hir::AttrPath {
@@ -52,21 +37,15 @@ impl<'a> PathParser<'a> {
     }
 
     pub fn segments(&'a self) -> impl Iterator<Item = &'a Ident> {
-        SegmentIterator { offset: 0, path: self }
+        self.0.segments.iter().map(|seg| &seg.ident)
     }
 
     pub fn span(&self) -> Span {
-        match self {
-            PathParser::Ast(path) => path.span,
-            PathParser::Attr(attr_path) => attr_path.span,
-        }
+        self.0.span
     }
 
     pub fn len(&self) -> usize {
-        match self {
-            PathParser::Ast(path) => path.segments.len(),
-            PathParser::Attr(attr_path) => attr_path.segments.len(),
-        }
+        self.0.segments.len()
     }
 
     pub fn segments_is(&self, segments: &[Symbol]) -> bool {
@@ -99,10 +78,7 @@ impl<'a> PathParser<'a> {
 
 impl Display for PathParser<'_> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match self {
-            PathParser::Ast(path) => write!(f, "{}", pprust::path_to_string(path)),
-            PathParser::Attr(attr_path) => write!(f, "{attr_path}"),
-        }
+        write!(f, "{}", pprust::path_to_string(&self.0))
     }
 }
 
@@ -123,21 +99,39 @@ impl<'a> ArgParser<'a> {
         }
     }
 
-    pub fn from_attr_args<'sess>(value: &'a AttrArgs, dcx: DiagCtxtHandle<'sess>) -> Self {
-        match value {
+    pub fn from_attr_args<'sess>(
+        value: &'a AttrArgs,
+        parts: &[Symbol],
+        psess: &'sess ParseSess,
+        should_emit: ShouldEmit,
+    ) -> Option<Self> {
+        Some(match value {
             AttrArgs::Empty => Self::NoArgs,
-            AttrArgs::Delimited(args) if args.delim == Delimiter::Parenthesis => {
-                Self::List(MetaItemListParser::new(args, dcx))
-            }
             AttrArgs::Delimited(args) => {
-                Self::List(MetaItemListParser { sub_parsers: vec![], span: args.dspan.entire() })
+                // The arguments of rustc_dummy are not validated if the arguments are delimited
+                if parts == &[sym::rustc_dummy] {
+                    return Some(ArgParser::List(MetaItemListParser {
+                        sub_parsers: ThinVec::new(),
+                        span: args.dspan.entire(),
+                    }));
+                }
+
+                if args.delim != Delimiter::Parenthesis {
+                    psess.dcx().emit_err(MetaBadDelim {
+                        span: args.dspan.entire(),
+                        sugg: MetaBadDelimSugg { open: args.dspan.open, close: args.dspan.close },
+                    });
+                    return None;
+                }
+
+                Self::List(MetaItemListParser::new(args, psess, should_emit)?)
             }
             AttrArgs::Eq { eq_span, expr } => Self::NameValue(NameValueParser {
                 eq_span: *eq_span,
-                value: expr_to_lit(dcx, &expr, *eq_span),
+                value: expr_to_lit(psess, &expr, expr.span, should_emit)?,
                 value_span: expr.span,
             }),
-        }
+        })
     }
 
     /// Asserts that this MetaItem is a list
@@ -249,11 +243,16 @@ impl<'a> Debug for MetaItemParser<'a> {
 impl<'a> MetaItemParser<'a> {
     /// Create a new parser from a [`NormalAttr`], which is stored inside of any
     /// [`ast::Attribute`](rustc_ast::Attribute)
-    pub fn from_attr<'sess>(attr: &'a NormalAttr, dcx: DiagCtxtHandle<'sess>) -> Self {
-        Self {
-            path: PathParser::Ast(&attr.item.path),
-            args: ArgParser::from_attr_args(&attr.item.args, dcx),
-        }
+    pub fn from_attr<'sess>(
+        attr: &'a NormalAttr,
+        parts: &[Symbol],
+        psess: &'sess ParseSess,
+        should_emit: ShouldEmit,
+    ) -> Option<Self> {
+        Some(Self {
+            path: PathParser(Cow::Borrowed(&attr.item.path)),
+            args: ArgParser::from_attr_args(&attr.item.args, parts, psess, should_emit)?,
+        })
     }
 }
 
@@ -318,215 +317,235 @@ impl NameValueParser {
     }
 }
 
-fn expr_to_lit(dcx: DiagCtxtHandle<'_>, expr: &Expr, span: Span) -> MetaItemLit {
-    // In valid code the value always ends up as a single literal. Otherwise, a dummy
-    // literal suffices because the error is handled elsewhere.
-    if let ExprKind::Lit(token_lit) = expr.kind
-        && let Ok(lit) = MetaItemLit::from_token_lit(token_lit, expr.span)
-    {
-        lit
+fn expr_to_lit(
+    psess: &ParseSess,
+    expr: &Expr,
+    span: Span,
+    should_emit: ShouldEmit,
+) -> Option<MetaItemLit> {
+    if let ExprKind::Lit(token_lit) = expr.kind {
+        let res = MetaItemLit::from_token_lit(token_lit, expr.span);
+        match res {
+            Ok(lit) => {
+                if token_lit.suffix.is_some() {
+                    should_emit.emit_err(
+                        psess.dcx().create_err(SuffixedLiteralInAttribute { span: lit.span }),
+                    );
+                    None
+                } else {
+                    if !lit.kind.is_unsuffixed() {
+                        // Emit error and continue, we can still parse the attribute as if the suffix isn't there
+                        should_emit.emit_err(
+                            psess.dcx().create_err(SuffixedLiteralInAttribute { span: lit.span }),
+                        );
+                    }
+
+                    Some(lit)
+                }
+            }
+            Err(err) => {
+                let guar = report_lit_error(psess, err, token_lit, expr.span);
+                let lit = MetaItemLit {
+                    symbol: token_lit.symbol,
+                    suffix: token_lit.suffix,
+                    kind: LitKind::Err(guar),
+                    span: expr.span,
+                };
+                Some(lit)
+            }
+        }
     } else {
-        let guar = dcx.span_delayed_bug(
-            span,
-            "expr in place where literal is expected (builtin attr parsing)",
-        );
-        MetaItemLit { symbol: sym::dummy, suffix: None, kind: LitKind::Err(guar), span }
+        if matches!(should_emit, ShouldEmit::Nothing) {
+            return None;
+        }
+
+        // Example cases:
+        // - `#[foo = 1+1]`: results in `ast::ExprKind::BinOp`.
+        // - `#[foo = include_str!("nonexistent-file.rs")]`:
+        //   results in `ast::ExprKind::Err`. In that case we delay
+        //   the error because an earlier error will have already
+        //   been reported.
+        let msg = "attribute value must be a literal";
+        let err = psess.dcx().struct_span_err(span, msg);
+        should_emit.emit_err(err);
+        None
     }
 }
 
 struct MetaItemListParserContext<'a, 'sess> {
-    // the tokens inside the delimiters, so `#[some::attr(a b c)]` would have `a b c` inside
-    inside_delimiters: Peekable<TokenStreamIter<'a>>,
-    dcx: DiagCtxtHandle<'sess>,
+    parser: &'a mut Parser<'sess>,
+    should_emit: ShouldEmit,
 }
 
 impl<'a, 'sess> MetaItemListParserContext<'a, 'sess> {
-    fn done(&mut self) -> bool {
-        self.inside_delimiters.peek().is_none()
-    }
-
-    fn next_path(&mut self) -> Option<AttrPath> {
-        // FIXME: Share code with `parse_path`.
-        let tt = self.inside_delimiters.next().map(|tt| TokenTree::uninterpolate(tt));
-
-        match tt.as_deref()? {
-            &TokenTree::Token(
-                Token { kind: ref kind @ (token::Ident(..) | token::PathSep), span },
-                _,
-            ) => {
-                // here we have either an ident or pathsep `::`.
-
-                let mut segments = if let &token::Ident(name, _) = kind {
-                    // when we lookahead another pathsep, more path's coming
-                    if let Some(TokenTree::Token(Token { kind: token::PathSep, .. }, _)) =
-                        self.inside_delimiters.peek()
-                    {
-                        self.inside_delimiters.next();
-                        vec![Ident::new(name, span)]
-                    } else {
-                        // else we have a single identifier path, that's all
-                        return Some(AttrPath {
-                            segments: vec![Ident::new(name, span)].into_boxed_slice(),
-                            span,
-                        });
-                    }
-                } else {
-                    // if `::` is all we get, we just got a path root
-                    vec![Ident::new(kw::PathRoot, span)]
-                };
+    fn parse_unsuffixed_meta_item_lit(&mut self) -> PResult<'sess, MetaItemLit> {
+        let uninterpolated_span = self.parser.token_uninterpolated_span();
+        let Some(token_lit) = self.parser.eat_token_lit() else {
+            return self.parser.handle_missing_lit(Parser::mk_meta_item_lit_char);
+        };
 
-                // one segment accepted. accept n more
-                loop {
-                    // another ident?
-                    if let Some(&TokenTree::Token(Token { kind: token::Ident(name, _), span }, _)) =
-                        self.inside_delimiters
-                            .next()
-                            .map(|tt| TokenTree::uninterpolate(tt))
-                            .as_deref()
-                    {
-                        segments.push(Ident::new(name, span));
-                    } else {
-                        return None;
-                    }
-                    // stop unless we see another `::`
-                    if let Some(TokenTree::Token(Token { kind: token::PathSep, .. }, _)) =
-                        self.inside_delimiters.peek()
-                    {
-                        self.inside_delimiters.next();
-                    } else {
-                        break;
-                    }
-                }
-                let span = span.with_hi(segments.last().unwrap().span.hi());
-                Some(AttrPath { segments: segments.into_boxed_slice(), span })
-            }
-            TokenTree::Token(Token { kind, .. }, _) if kind.is_delim() => None,
-            _ => {
-                // malformed attributes can get here. We can't crash, but somewhere else should've
-                // already warned for this.
-                None
+        let lit = match MetaItemLit::from_token_lit(token_lit, self.parser.prev_token.span) {
+            Ok(lit) => lit,
+            Err(err) => {
+                let guar =
+                    report_lit_error(&self.parser.psess, err, token_lit, uninterpolated_span);
+                // Pack possible quotes and prefixes from the original literal into
+                // the error literal's symbol so they can be pretty-printed faithfully.
+                let suffixless_lit = token::Lit::new(token_lit.kind, token_lit.symbol, None);
+                let symbol = Symbol::intern(&suffixless_lit.to_string());
+                let token_lit = token::Lit::new(token::Err(guar), symbol, token_lit.suffix);
+                MetaItemLit::from_token_lit(token_lit, uninterpolated_span).unwrap()
             }
+        };
+
+        if !lit.kind.is_unsuffixed() {
+            // Emit error and continue, we can still parse the attribute as if the suffix isn't there
+            self.should_emit.emit_err(
+                self.parser.dcx().create_err(SuffixedLiteralInAttribute { span: lit.span }),
+            );
         }
-    }
 
-    fn value(&mut self) -> Option<MetaItemLit> {
-        match self.inside_delimiters.next() {
-            Some(TokenTree::Delimited(.., Delimiter::Invisible(_), inner_tokens)) => {
-                MetaItemListParserContext {
-                    inside_delimiters: inner_tokens.iter().peekable(),
-                    dcx: self.dcx,
-                }
-                .value()
-            }
-            Some(TokenTree::Token(token, _)) => MetaItemLit::from_token(token),
-            _ => None,
+        Ok(lit)
+    }
+
+    fn parse_attr_item(&mut self) -> PResult<'sess, MetaItemParser<'static>> {
+        if let Some(MetaVarKind::Meta { has_meta_form }) = self.parser.token.is_metavar_seq() {
+            return if has_meta_form {
+                let attr_item = self
+                    .parser
+                    .eat_metavar_seq(MetaVarKind::Meta { has_meta_form: true }, |this| {
+                        MetaItemListParserContext { parser: this, should_emit: self.should_emit }
+                            .parse_attr_item()
+                    })
+                    .unwrap();
+                Ok(attr_item)
+            } else {
+                self.parser.unexpected_any()
+            };
         }
+
+        let path = self.parser.parse_path(PathStyle::Mod)?;
+
+        // Check style of arguments that this meta item has
+        let args = if self.parser.check(exp!(OpenParen)) {
+            let start = self.parser.token.span;
+            let (sub_parsers, _) = self.parser.parse_paren_comma_seq(|parser| {
+                MetaItemListParserContext { parser, should_emit: self.should_emit }
+                    .parse_meta_item_inner()
+            })?;
+            let end = self.parser.prev_token.span;
+            ArgParser::List(MetaItemListParser { sub_parsers, span: start.with_hi(end.hi()) })
+        } else if self.parser.eat(exp!(Eq)) {
+            let eq_span = self.parser.prev_token.span;
+            let value = self.parse_unsuffixed_meta_item_lit()?;
+
+            ArgParser::NameValue(NameValueParser { eq_span, value, value_span: value.span })
+        } else {
+            ArgParser::NoArgs
+        };
+
+        Ok(MetaItemParser { path: PathParser(Cow::Owned(path)), args })
     }
 
-    /// parses one element on the inside of a list attribute like `#[my_attr( <insides> )]`
-    ///
-    /// parses a path followed be either:
-    /// 1. nothing (a word attr)
-    /// 2. a parenthesized list
-    /// 3. an equals sign and a literal (name-value)
-    ///
-    /// Can also parse *just* a literal. This is for cases like as `#[my_attr("literal")]`
-    /// where no path is given before the literal
-    ///
-    /// Some exceptions too for interpolated attributes which are already pre-processed
-    fn next(&mut self) -> Option<MetaItemOrLitParser<'a>> {
-        // a list element is either a literal
-        if let Some(TokenTree::Token(token, _)) = self.inside_delimiters.peek()
-            && let Some(lit) = MetaItemLit::from_token(token)
-        {
-            self.inside_delimiters.next();
-            return Some(MetaItemOrLitParser::Lit(lit));
-        } else if let Some(TokenTree::Delimited(.., Delimiter::Invisible(_), inner_tokens)) =
-            self.inside_delimiters.peek()
+    fn parse_meta_item_inner(&mut self) -> PResult<'sess, MetaItemOrLitParser<'static>> {
+        match self.parse_unsuffixed_meta_item_lit() {
+            Ok(lit) => return Ok(MetaItemOrLitParser::Lit(lit)),
+            Err(err) => err.cancel(), // we provide a better error below
+        }
+
+        match self.parse_attr_item() {
+            Ok(mi) => return Ok(MetaItemOrLitParser::MetaItemParser(mi)),
+            Err(err) => err.cancel(), // we provide a better error below
+        }
+
+        let mut err = InvalidMetaItem {
+            span: self.parser.token.span,
+            descr: token_descr(&self.parser.token),
+            quote_ident_sugg: None,
+            remove_neg_sugg: None,
+        };
+
+        // Suggest quoting idents, e.g. in `#[cfg(key = value)]`. We don't use `Token::ident` and
+        // don't `uninterpolate` the token to avoid suggesting anything butchered or questionable
+        // when macro metavariables are involved.
+        if self.parser.prev_token == token::Eq
+            && let token::Ident(..) = self.parser.token.kind
         {
-            self.inside_delimiters.next();
-            return MetaItemListParserContext {
-                inside_delimiters: inner_tokens.iter().peekable(),
-                dcx: self.dcx,
+            let before = self.parser.token.span.shrink_to_lo();
+            while let token::Ident(..) = self.parser.token.kind {
+                self.parser.bump();
             }
-            .next();
+            err.quote_ident_sugg = Some(InvalidMetaItemQuoteIdentSugg {
+                before,
+                after: self.parser.prev_token.span.shrink_to_hi(),
+            });
         }
 
-        // or a path.
-        let path = self.next_path()?;
-
-        // Paths can be followed by:
-        // - `(more meta items)` (another list)
-        // - `= lit` (a name-value)
-        // - nothing
-        Some(MetaItemOrLitParser::MetaItemParser(match self.inside_delimiters.peek() {
-            Some(TokenTree::Delimited(dspan, _, Delimiter::Parenthesis, inner_tokens)) => {
-                self.inside_delimiters.next();
-
-                MetaItemParser {
-                    path: PathParser::Attr(path),
-                    args: ArgParser::List(MetaItemListParser::new_tts(
-                        inner_tokens.iter(),
-                        dspan.entire(),
-                        self.dcx,
-                    )),
-                }
-            }
-            Some(TokenTree::Delimited(_, ..)) => {
-                self.inside_delimiters.next();
-                // self.dcx.span_delayed_bug(span.entire(), "wrong delimiters");
-                return None;
-            }
-            Some(TokenTree::Token(Token { kind: token::Eq, span }, _)) => {
-                self.inside_delimiters.next();
-                let value = self.value()?;
-                MetaItemParser {
-                    path: PathParser::Attr(path),
-                    args: ArgParser::NameValue(NameValueParser {
-                        eq_span: *span,
-                        value_span: value.span,
-                        value,
-                    }),
-                }
-            }
-            _ => MetaItemParser { path: PathParser::Attr(path), args: ArgParser::NoArgs },
-        }))
+        if self.parser.token == token::Minus
+            && self
+                .parser
+                .look_ahead(1, |t| matches!(t.kind, rustc_ast::token::TokenKind::Literal { .. }))
+        {
+            err.remove_neg_sugg =
+                Some(InvalidMetaItemRemoveNegSugg { negative_sign: self.parser.token.span });
+            self.parser.bump();
+            self.parser.bump();
+        }
+
+        Err(self.parser.dcx().create_err(err))
     }
 
-    fn parse(mut self, span: Span) -> MetaItemListParser<'a> {
-        let mut sub_parsers = Vec::new();
+    fn parse(
+        tokens: TokenStream,
+        psess: &'sess ParseSess,
+        span: Span,
+        should_emit: ShouldEmit,
+    ) -> PResult<'sess, MetaItemListParser<'static>> {
+        let mut parser = Parser::new(psess, tokens, None);
+        let mut this = MetaItemListParserContext { parser: &mut parser, should_emit };
 
-        while !self.done() {
-            let Some(n) = self.next() else {
-                continue;
-            };
-            sub_parsers.push(n);
+        // Presumably, the majority of the time there will only be one attr.
+        let mut sub_parsers = ThinVec::with_capacity(1);
+        while this.parser.token != token::Eof {
+            sub_parsers.push(this.parse_meta_item_inner()?);
 
-            match self.inside_delimiters.peek() {
-                None | Some(TokenTree::Token(Token { kind: token::Comma, .. }, _)) => {
-                    self.inside_delimiters.next();
-                }
-                Some(_) => {}
+            if !this.parser.eat(exp!(Comma)) {
+                break;
             }
         }
 
-        MetaItemListParser { sub_parsers, span }
+        if parser.token != token::Eof {
+            parser.unexpected()?;
+        }
+
+        Ok(MetaItemListParser { sub_parsers, span })
     }
 }
 
 #[derive(Debug, Clone)]
 pub struct MetaItemListParser<'a> {
-    sub_parsers: Vec<MetaItemOrLitParser<'a>>,
+    sub_parsers: ThinVec<MetaItemOrLitParser<'a>>,
     pub span: Span,
 }
 
 impl<'a> MetaItemListParser<'a> {
-    fn new<'sess>(delim: &'a DelimArgs, dcx: DiagCtxtHandle<'sess>) -> Self {
-        MetaItemListParser::new_tts(delim.tokens.iter(), delim.dspan.entire(), dcx)
-    }
-
-    fn new_tts<'sess>(tts: TokenStreamIter<'a>, span: Span, dcx: DiagCtxtHandle<'sess>) -> Self {
-        MetaItemListParserContext { inside_delimiters: tts.peekable(), dcx }.parse(span)
+    fn new<'sess>(
+        delim: &'a DelimArgs,
+        psess: &'sess ParseSess,
+        should_emit: ShouldEmit,
+    ) -> Option<Self> {
+        match MetaItemListParserContext::parse(
+            delim.tokens.clone(),
+            psess,
+            delim.dspan.entire(),
+            should_emit,
+        ) {
+            Ok(s) => Some(s),
+            Err(e) => {
+                should_emit.emit_err(e);
+                None
+            }
+        }
     }
 
     /// Lets you pick and choose as what you want to parse each element in the list
diff --git a/compiler/rustc_attr_parsing/src/session_diagnostics.rs b/compiler/rustc_attr_parsing/src/session_diagnostics.rs
index 41179844152..a9dee23bf6a 100644
--- a/compiler/rustc_attr_parsing/src/session_diagnostics.rs
+++ b/compiler/rustc_attr_parsing/src/session_diagnostics.rs
@@ -1,12 +1,12 @@
 use std::num::IntErrorKind;
 
-use rustc_ast as ast;
+use rustc_ast::{self as ast, AttrStyle, Path};
 use rustc_errors::codes::*;
 use rustc_errors::{
     Applicability, Diag, DiagArgValue, DiagCtxtHandle, Diagnostic, EmissionGuarantee, Level,
 };
 use rustc_feature::AttributeTemplate;
-use rustc_hir::AttrPath;
+use rustc_hir::{AttrPath, Target};
 use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
 use rustc_span::{Span, Symbol};
 
@@ -480,6 +480,32 @@ pub(crate) struct EmptyAttributeList {
     pub attr_span: Span,
 }
 
+#[derive(LintDiagnostic)]
+#[diag(attr_parsing_invalid_target_lint)]
+#[warning]
+#[help]
+pub(crate) struct InvalidTargetLint {
+    pub name: AttrPath,
+    pub target: &'static str,
+    pub applied: DiagArgValue,
+    pub only: &'static str,
+    #[suggestion(code = "", applicability = "machine-applicable", style = "tool-only")]
+    pub attr_span: Span,
+}
+
+#[derive(Diagnostic)]
+#[help]
+#[diag(attr_parsing_invalid_target)]
+pub(crate) struct InvalidTarget {
+    #[primary_span]
+    #[suggestion(code = "", applicability = "machine-applicable", style = "tool-only")]
+    pub span: Span,
+    pub name: AttrPath,
+    pub target: &'static str,
+    pub applied: DiagArgValue,
+    pub only: &'static str,
+}
+
 #[derive(Diagnostic)]
 #[diag(attr_parsing_invalid_alignment_value, code = E0589)]
 pub(crate) struct InvalidAlignmentValue {
@@ -532,7 +558,7 @@ pub(crate) struct LinkOrdinalOutOfRange {
     pub ordinal: u128,
 }
 
-pub(crate) enum AttributeParseErrorReason {
+pub(crate) enum AttributeParseErrorReason<'a> {
     ExpectedNoArgs,
     ExpectedStringLiteral {
         byte_string: Option<Span>,
@@ -545,7 +571,7 @@ pub(crate) enum AttributeParseErrorReason {
     ExpectedNameValue(Option<Symbol>),
     DuplicateKey(Symbol),
     ExpectedSpecificArgument {
-        possibilities: Vec<&'static str>,
+        possibilities: &'a [Symbol],
         strings: bool,
         /// Should we tell the user to write a list when they didn't?
         list: bool,
@@ -553,15 +579,16 @@ pub(crate) enum AttributeParseErrorReason {
     ExpectedIdentifier,
 }
 
-pub(crate) struct AttributeParseError {
+pub(crate) struct AttributeParseError<'a> {
     pub(crate) span: Span,
     pub(crate) attr_span: Span,
+    pub(crate) attr_style: AttrStyle,
     pub(crate) template: AttributeTemplate,
     pub(crate) attribute: AttrPath,
-    pub(crate) reason: AttributeParseErrorReason,
+    pub(crate) reason: AttributeParseErrorReason<'a>,
 }
 
-impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for AttributeParseError {
+impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for AttributeParseError<'_> {
     fn into_diag(self, dcx: DiagCtxtHandle<'a>, level: Level) -> Diag<'a, G> {
         let name = self.attribute.to_string();
 
@@ -630,7 +657,7 @@ impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for AttributeParseError {
                 list: false,
             } => {
                 let quote = if strings { '"' } else { '`' };
-                match possibilities.as_slice() {
+                match possibilities {
                     &[] => {}
                     &[x] => {
                         diag.span_label(
@@ -660,7 +687,7 @@ impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for AttributeParseError {
                 list: true,
             } => {
                 let quote = if strings { '"' } else { '`' };
-                match possibilities.as_slice() {
+                match possibilities {
                     &[] => {}
                     &[x] => {
                         diag.span_label(
@@ -694,7 +721,8 @@ impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for AttributeParseError {
         if let Some(link) = self.template.docs {
             diag.note(format!("for more information, visit <{link}>"));
         }
-        let suggestions = self.template.suggestions(false, &name);
+        let suggestions = self.template.suggestions(self.attr_style, &name);
+
         diag.span_suggestions(
             self.attr_span,
             if suggestions.len() == 1 {
@@ -709,3 +737,196 @@ impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for AttributeParseError {
         diag
     }
 }
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_invalid_attr_unsafe)]
+#[note]
+pub(crate) struct InvalidAttrUnsafe {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    pub name: Path,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_unsafe_attr_outside_unsafe)]
+pub(crate) struct UnsafeAttrOutsideUnsafe {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+    #[subdiagnostic]
+    pub suggestion: UnsafeAttrOutsideUnsafeSuggestion,
+}
+
+#[derive(Subdiagnostic)]
+#[multipart_suggestion(
+    attr_parsing_unsafe_attr_outside_unsafe_suggestion,
+    applicability = "machine-applicable"
+)]
+pub(crate) struct UnsafeAttrOutsideUnsafeSuggestion {
+    #[suggestion_part(code = "unsafe(")]
+    pub left: Span,
+    #[suggestion_part(code = ")")]
+    pub right: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_meta_bad_delim)]
+pub(crate) struct MetaBadDelim {
+    #[primary_span]
+    pub span: Span,
+    #[subdiagnostic]
+    pub sugg: MetaBadDelimSugg,
+}
+
+#[derive(Subdiagnostic)]
+#[multipart_suggestion(
+    attr_parsing_meta_bad_delim_suggestion,
+    applicability = "machine-applicable"
+)]
+pub(crate) struct MetaBadDelimSugg {
+    #[suggestion_part(code = "(")]
+    pub open: Span,
+    #[suggestion_part(code = ")")]
+    pub close: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_invalid_meta_item)]
+pub(crate) struct InvalidMetaItem {
+    #[primary_span]
+    pub span: Span,
+    pub descr: String,
+    #[subdiagnostic]
+    pub quote_ident_sugg: Option<InvalidMetaItemQuoteIdentSugg>,
+    #[subdiagnostic]
+    pub remove_neg_sugg: Option<InvalidMetaItemRemoveNegSugg>,
+}
+
+#[derive(Subdiagnostic)]
+#[multipart_suggestion(attr_parsing_quote_ident_sugg, applicability = "machine-applicable")]
+pub(crate) struct InvalidMetaItemQuoteIdentSugg {
+    #[suggestion_part(code = "\"")]
+    pub before: Span,
+    #[suggestion_part(code = "\"")]
+    pub after: Span,
+}
+
+#[derive(Subdiagnostic)]
+#[multipart_suggestion(attr_parsing_remove_neg_sugg, applicability = "machine-applicable")]
+pub(crate) struct InvalidMetaItemRemoveNegSugg {
+    #[suggestion_part(code = "")]
+    pub negative_sign: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_suffixed_literal_in_attribute)]
+#[help]
+pub(crate) struct SuffixedLiteralInAttribute {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(LintDiagnostic)]
+#[diag(attr_parsing_invalid_style)]
+pub(crate) struct InvalidAttrStyle {
+    pub name: AttrPath,
+    pub is_used_as_inner: bool,
+    #[note]
+    pub target_span: Option<Span>,
+    pub target: Target,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_empty_link_name, code = E0454)]
+pub(crate) struct EmptyLinkName {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_link_framework_apple, code = E0455)]
+pub(crate) struct LinkFrameworkApple {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_incompatible_wasm_link)]
+pub(crate) struct IncompatibleWasmLink {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_link_requires_name, code = E0459)]
+pub(crate) struct LinkRequiresName {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_raw_dylib_no_nul)]
+pub(crate) struct RawDylibNoNul {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_raw_dylib_only_windows, code = E0455)]
+pub(crate) struct RawDylibOnlyWindows {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_invalid_link_modifier)]
+pub(crate) struct InvalidLinkModifier {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_multiple_modifiers)]
+pub(crate) struct MultipleModifiers {
+    #[primary_span]
+    pub span: Span,
+    pub modifier: Symbol,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_import_name_type_x86)]
+pub(crate) struct ImportNameTypeX86 {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_bundle_needs_static)]
+pub(crate) struct BundleNeedsStatic {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_whole_archive_needs_static)]
+pub(crate) struct WholeArchiveNeedsStatic {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_as_needed_compatibility)]
+pub(crate) struct AsNeededCompatibility {
+    #[primary_span]
+    pub span: Span,
+}
+
+#[derive(Diagnostic)]
+#[diag(attr_parsing_import_name_type_raw)]
+pub(crate) struct ImportNameTypeRaw {
+    #[primary_span]
+    pub span: Span,
+}
diff --git a/compiler/rustc_attr_parsing/src/target_checking.rs b/compiler/rustc_attr_parsing/src/target_checking.rs
new file mode 100644
index 00000000000..edc496b460c
--- /dev/null
+++ b/compiler/rustc_attr_parsing/src/target_checking.rs
@@ -0,0 +1,269 @@
+use std::borrow::Cow;
+
+use rustc_ast::AttrStyle;
+use rustc_errors::DiagArgValue;
+use rustc_feature::{AttributeType, Features};
+use rustc_hir::lints::AttributeLintKind;
+use rustc_hir::{MethodKind, Target};
+
+use crate::AttributeParser;
+use crate::context::{AcceptContext, Stage};
+use crate::session_diagnostics::InvalidTarget;
+
+#[derive(Debug)]
+pub(crate) enum AllowedTargets {
+    AllowList(&'static [Policy]),
+    AllowListWarnRest(&'static [Policy]),
+}
+
+pub(crate) enum AllowedResult {
+    Allowed,
+    Warn,
+    Error,
+}
+
+impl AllowedTargets {
+    pub(crate) fn is_allowed(&self, target: Target) -> AllowedResult {
+        match self {
+            AllowedTargets::AllowList(list) => {
+                if list.contains(&Policy::Allow(target)) {
+                    AllowedResult::Allowed
+                } else if list.contains(&Policy::Warn(target)) {
+                    AllowedResult::Warn
+                } else {
+                    AllowedResult::Error
+                }
+            }
+            AllowedTargets::AllowListWarnRest(list) => {
+                if list.contains(&Policy::Allow(target)) {
+                    AllowedResult::Allowed
+                } else if list.contains(&Policy::Error(target)) {
+                    AllowedResult::Error
+                } else {
+                    AllowedResult::Warn
+                }
+            }
+        }
+    }
+
+    pub(crate) fn allowed_targets(&self) -> Vec<Target> {
+        match self {
+            AllowedTargets::AllowList(list) => list,
+            AllowedTargets::AllowListWarnRest(list) => list,
+        }
+        .iter()
+        .filter_map(|target| match target {
+            Policy::Allow(target) => Some(*target),
+            Policy::Warn(_) => None,
+            Policy::Error(_) => None,
+        })
+        .collect()
+    }
+}
+
+#[derive(Debug, Eq, PartialEq)]
+pub(crate) enum Policy {
+    Allow(Target),
+    Warn(Target),
+    Error(Target),
+}
+
+impl<'sess, S: Stage> AttributeParser<'sess, S> {
+    pub(crate) fn check_target(
+        allowed_targets: &AllowedTargets,
+        target: Target,
+        cx: &mut AcceptContext<'_, 'sess, S>,
+    ) {
+        match allowed_targets.is_allowed(target) {
+            AllowedResult::Allowed => {}
+            AllowedResult::Warn => {
+                let allowed_targets = allowed_targets.allowed_targets();
+                let (applied, only) = allowed_targets_applied(allowed_targets, target, cx.features);
+                let name = cx.attr_path.clone();
+                let attr_span = cx.attr_span;
+                cx.emit_lint(
+                    AttributeLintKind::InvalidTarget {
+                        name,
+                        target,
+                        only: if only { "only " } else { "" },
+                        applied,
+                    },
+                    attr_span,
+                );
+            }
+            AllowedResult::Error => {
+                let allowed_targets = allowed_targets.allowed_targets();
+                let (applied, only) = allowed_targets_applied(allowed_targets, target, cx.features);
+                let name = cx.attr_path.clone();
+                cx.dcx().emit_err(InvalidTarget {
+                    span: cx.attr_span.clone(),
+                    name,
+                    target: target.plural_name(),
+                    only: if only { "only " } else { "" },
+                    applied: DiagArgValue::StrListSepByAnd(
+                        applied.into_iter().map(Cow::Owned).collect(),
+                    ),
+                });
+            }
+        }
+    }
+
+    pub(crate) fn check_type(
+        attribute_type: AttributeType,
+        target: Target,
+        cx: &mut AcceptContext<'_, 'sess, S>,
+    ) {
+        let is_crate_root = S::id_is_crate_root(cx.target_id);
+
+        if is_crate_root {
+            return;
+        }
+
+        if attribute_type != AttributeType::CrateLevel {
+            return;
+        }
+
+        let lint = AttributeLintKind::InvalidStyle {
+            name: cx.attr_path.clone(),
+            is_used_as_inner: cx.attr_style == AttrStyle::Inner,
+            target,
+            target_span: cx.target_span,
+        };
+        let attr_span = cx.attr_span;
+
+        cx.emit_lint(lint, attr_span);
+    }
+}
+
+/// Takes a list of `allowed_targets` for an attribute, and the `target` the attribute was applied to.
+/// Does some heuristic-based filtering to remove uninteresting targets, and formats the targets into a string
+pub(crate) fn allowed_targets_applied(
+    mut allowed_targets: Vec<Target>,
+    target: Target,
+    features: Option<&Features>,
+) -> (Vec<String>, bool) {
+    // Remove unstable targets from `allowed_targets` if their features are not enabled
+    if let Some(features) = features {
+        if !features.fn_delegation() {
+            allowed_targets.retain(|t| !matches!(t, Target::Delegation { .. }));
+        }
+        if !features.stmt_expr_attributes() {
+            allowed_targets.retain(|t| !matches!(t, Target::Expression | Target::Statement));
+        }
+        if !features.extern_types() {
+            allowed_targets.retain(|t| !matches!(t, Target::ForeignTy));
+        }
+    }
+
+    // We define groups of "similar" targets.
+    // If at least two of the targets are allowed, and the `target` is not in the group,
+    // we collapse the entire group to a single entry to simplify the target list
+    const FUNCTION_LIKE: &[Target] = &[
+        Target::Fn,
+        Target::Closure,
+        Target::ForeignFn,
+        Target::Method(MethodKind::Inherent),
+        Target::Method(MethodKind::Trait { body: false }),
+        Target::Method(MethodKind::Trait { body: true }),
+        Target::Method(MethodKind::TraitImpl),
+    ];
+    const METHOD_LIKE: &[Target] = &[
+        Target::Method(MethodKind::Inherent),
+        Target::Method(MethodKind::Trait { body: false }),
+        Target::Method(MethodKind::Trait { body: true }),
+        Target::Method(MethodKind::TraitImpl),
+    ];
+    const IMPL_LIKE: &[Target] =
+        &[Target::Impl { of_trait: false }, Target::Impl { of_trait: true }];
+    const ADT_LIKE: &[Target] = &[Target::Struct, Target::Enum];
+
+    let mut added_fake_targets = Vec::new();
+    filter_targets(
+        &mut allowed_targets,
+        FUNCTION_LIKE,
+        "functions",
+        target,
+        &mut added_fake_targets,
+    );
+    filter_targets(&mut allowed_targets, METHOD_LIKE, "methods", target, &mut added_fake_targets);
+    filter_targets(&mut allowed_targets, IMPL_LIKE, "impl blocks", target, &mut added_fake_targets);
+    filter_targets(&mut allowed_targets, ADT_LIKE, "data types", target, &mut added_fake_targets);
+
+    // If there is now only 1 target left, show that as the only possible target
+    (
+        added_fake_targets
+            .iter()
+            .copied()
+            .chain(allowed_targets.iter().map(|t| t.plural_name()))
+            .map(|i| i.to_string())
+            .collect(),
+        allowed_targets.len() + added_fake_targets.len() == 1,
+    )
+}
+
+fn filter_targets(
+    allowed_targets: &mut Vec<Target>,
+    target_group: &'static [Target],
+    target_group_name: &'static str,
+    target: Target,
+    added_fake_targets: &mut Vec<&'static str>,
+) {
+    if target_group.contains(&target) {
+        return;
+    }
+    if allowed_targets.iter().filter(|at| target_group.contains(at)).count() < 2 {
+        return;
+    }
+    allowed_targets.retain(|t| !target_group.contains(t));
+    added_fake_targets.push(target_group_name);
+}
+
+/// This is the list of all targets to which a attribute can be applied
+/// This is used for:
+/// - `rustc_dummy`, which can be applied to all targets
+/// - Attributes that are not parted to the new target system yet can use this list as a placeholder
+pub(crate) const ALL_TARGETS: &'static [Policy] = {
+    use Policy::Allow;
+    &[
+        Allow(Target::ExternCrate),
+        Allow(Target::Use),
+        Allow(Target::Static),
+        Allow(Target::Const),
+        Allow(Target::Fn),
+        Allow(Target::Closure),
+        Allow(Target::Mod),
+        Allow(Target::ForeignMod),
+        Allow(Target::GlobalAsm),
+        Allow(Target::TyAlias),
+        Allow(Target::Enum),
+        Allow(Target::Variant),
+        Allow(Target::Struct),
+        Allow(Target::Field),
+        Allow(Target::Union),
+        Allow(Target::Trait),
+        Allow(Target::TraitAlias),
+        Allow(Target::Impl { of_trait: false }),
+        Allow(Target::Impl { of_trait: true }),
+        Allow(Target::Expression),
+        Allow(Target::Statement),
+        Allow(Target::Arm),
+        Allow(Target::AssocConst),
+        Allow(Target::Method(MethodKind::Inherent)),
+        Allow(Target::Method(MethodKind::Trait { body: false })),
+        Allow(Target::Method(MethodKind::Trait { body: true })),
+        Allow(Target::Method(MethodKind::TraitImpl)),
+        Allow(Target::AssocTy),
+        Allow(Target::ForeignFn),
+        Allow(Target::ForeignStatic),
+        Allow(Target::ForeignTy),
+        Allow(Target::MacroDef),
+        Allow(Target::Param),
+        Allow(Target::PatField),
+        Allow(Target::ExprField),
+        Allow(Target::WherePredicate),
+        Allow(Target::MacroCall),
+        Allow(Target::Crate),
+        Allow(Target::Delegation { mac: false }),
+        Allow(Target::Delegation { mac: true }),
+    ]
+};
diff --git a/compiler/rustc_parse/src/validate_attr.rs b/compiler/rustc_attr_parsing/src/validate_attr.rs
index 68ef6d6f32c..7a7624893bd 100644
--- a/compiler/rustc_parse/src/validate_attr.rs
+++ b/compiler/rustc_attr_parsing/src/validate_attr.rs
@@ -8,16 +8,16 @@ use rustc_ast::{
     self as ast, AttrArgs, Attribute, DelimArgs, MetaItem, MetaItemInner, MetaItemKind, NodeId,
     Path, Safety,
 };
-use rustc_attr_parsing::{AttributeParser, Late};
 use rustc_errors::{Applicability, DiagCtxtHandle, FatalError, PResult};
 use rustc_feature::{AttributeSafety, AttributeTemplate, BUILTIN_ATTRIBUTE_MAP, BuiltinAttribute};
+use rustc_parse::parse_in;
 use rustc_session::errors::report_lit_error;
 use rustc_session::lint::BuiltinLintDiag;
 use rustc_session::lint::builtin::{ILL_FORMED_ATTRIBUTE_INPUT, UNSAFE_ATTR_OUTSIDE_UNSAFE};
 use rustc_session::parse::ParseSess;
 use rustc_span::{Span, Symbol, sym};
 
-use crate::{errors, parse_in};
+use crate::{AttributeParser, Late, session_diagnostics as errors};
 
 pub fn check_attr(psess: &ParseSess, attr: &Attribute, id: NodeId) {
     if attr.is_doc_comment() || attr.has_name(sym::cfg_trace) || attr.has_name(sym::cfg_attr_trace)
@@ -33,7 +33,10 @@ pub fn check_attr(psess: &ParseSess, attr: &Attribute, id: NodeId) {
     // Check input tokens for built-in and key-value attributes.
     match builtin_attr_info {
         // `rustc_dummy` doesn't have any restrictions specific to built-in attributes.
-        Some(BuiltinAttribute { name, template, .. }) if *name != sym::rustc_dummy => {
+        Some(BuiltinAttribute { name, template, .. }) => {
+            if AttributeParser::<Late>::is_parsed_attribute(slice::from_ref(&name)) {
+                return;
+            }
             match parse_meta(psess, attr) {
                 // Don't check safety again, we just did that
                 Ok(meta) => {
@@ -133,16 +136,6 @@ fn check_meta_bad_delim(psess: &ParseSess, span: DelimSpan, delim: Delimiter) {
     });
 }
 
-pub(super) fn check_cfg_attr_bad_delim(psess: &ParseSess, span: DelimSpan, delim: Delimiter) {
-    if let Delimiter::Parenthesis = delim {
-        return;
-    }
-    psess.dcx().emit_err(errors::CfgAttrBadDelim {
-        span: span.entire(),
-        sugg: errors::MetaBadDelimSugg { open: span.open, close: span.close },
-    });
-}
-
 /// Checks that the given meta-item is compatible with this `AttributeTemplate`.
 fn is_attr_template_compatible(template: &AttributeTemplate, meta: &ast::MetaItemKind) -> bool {
     let is_one_allowed_subword = |items: &[MetaItemInner]| match items {
@@ -269,9 +262,6 @@ pub fn check_builtin_meta_item(
 ) {
     if !is_attr_template_compatible(&template, &meta.kind) {
         // attrs with new parsers are locally validated so excluded here
-        if AttributeParser::<Late>::is_parsed_attribute(slice::from_ref(&name)) {
-            return;
-        }
         emit_malformed_attribute(psess, style, meta.span, name, template);
     }
 
diff --git a/compiler/rustc_baked_icu_data/Cargo.toml b/compiler/rustc_baked_icu_data/Cargo.toml
index cb0e145386b..2f1ab7df379 100644
--- a/compiler/rustc_baked_icu_data/Cargo.toml
+++ b/compiler/rustc_baked_icu_data/Cargo.toml
@@ -5,9 +5,8 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-icu_list = "1.2"
-icu_locid = "1.2"
-icu_locid_transform = "1.3.2"
-icu_provider = { version = "1.2", features = ["sync"] }
-zerovec = "0.10.0"
+icu_list = { version = "2.0", default-features = false }
+icu_locale = { version = "2.0", default-features = false, features = ["compiled_data"] }
+icu_provider = { version = "2.0", features = ["baked", "sync"] }
+zerovec = "0.11.0"
 # tidy-alphabetical-end
diff --git a/compiler/rustc_baked_icu_data/src/data/any.rs b/compiler/rustc_baked_icu_data/src/data/any.rs
deleted file mode 100644
index 23028876676..00000000000
--- a/compiler/rustc_baked_icu_data/src/data/any.rs
+++ /dev/null
@@ -1,2 +0,0 @@
-// @generated
-impl_any_provider!(BakedDataProvider);
diff --git a/compiler/rustc_baked_icu_data/src/data/list_and_v1.rs.data b/compiler/rustc_baked_icu_data/src/data/list_and_v1.rs.data
new file mode 100644
index 00000000000..1d60e0085fc
--- /dev/null
+++ b/compiler/rustc_baked_icu_data/src/data/list_and_v1.rs.data
@@ -0,0 +1,71 @@
+// @generated
+/// Implement `DataProvider<ListAndV1>` on the given struct using the data
+/// hardcoded in this file. This allows the struct to be used with
+/// `icu`'s `_unstable` constructors.
+///
+/// Using this implementation will embed the following data in the binary's data segment:
+/// * 179B for the lookup data structure (33 data identifiers)
+/// * 4183B[^1] for the actual data (11 unique structs)
+///
+/// [^1]: these numbers can be smaller in practice due to linker deduplication
+///
+/// This macro requires the following crates:
+/// * `icu_list`
+/// * `icu_locale/compiled_data`
+/// * `icu_provider`
+/// * `icu_provider/baked`
+/// * `zerovec`
+#[doc(hidden)]
+#[macro_export]
+macro_rules! __impl_list_and_v1 {
+    ($ provider : ty) => {
+        #[clippy::msrv = "1.82"]
+        const _: () = <$provider>::MUST_USE_MAKE_PROVIDER_MACRO;
+        #[clippy::msrv = "1.82"]
+        impl $provider {
+            const DATA_LIST_AND_V1: icu_provider::baked::zerotrie::Data<icu_list::provider::ListAndV1> = {
+                const TRIE: icu_provider::baked::zerotrie::ZeroTrieSimpleAscii<&'static [u8]> = icu_provider::baked::zerotrie::ZeroTrieSimpleAscii { store: b"\xC8efijprtz\x18#.9DOZ\xC2ns\n\x1E\xC3NSW\x01\x02\x80\x85\x8A\x1E\xC3NSW\x01\x02\x81\x81\x81r\x1E\xC3NSW\x01\x02\x80\x86\x86t\x1E\xC3NSW\x01\x02\x82\x82\x82a\x1E\xC3NSW\x01\x02\x83\x83\x83t\x1E\xC3NSW\x01\x02\x80\x82\x82u\x1E\xC3NSW\x01\x02\x80\x87\x87r\x1E\xC3NSW\x01\x02\x80\x88\x88h\xC2\x1E-\t\xC3NSW\x01\x02\x83\x89\x89Han\xC2st\n\x1E\xC3NSW\x01\x02\x83\x89\x89\x1E\xC3NSW\x01\x02\x84\x89\x89" };
+                const VALUES: &'static [<icu_list::provider::ListAndV1 as icu_provider::baked::zerotrie::DynamicDataMarker>::DataStruct] = &[icu_list::provider::ListFormatterPatterns { start: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b", ") }, 2u8), middle: unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b", ") }, end: icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b", ") }, 2u8), special_case: None }, pair: None }, icu_list::provider::ListFormatterPatterns { start: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b", ") }, 2u8), middle: unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b", ") }, end: icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b" y ") }, 3u8), special_case: Some(icu_list::provider::SpecialCasePattern { condition: unsafe { icu_list::provider::SerdeDFA::from_dfa_bytes_unchecked(if cfg!(target_endian = "little") { 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} else { 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}) }, pattern: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b" e ") }, 3u8) }) }, pair: None }, icu_list::provider::ListFormatterPatterns { start: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b", ") }, 2u8), middle: unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b", ") }, end: icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b" e ") }, 3u8), special_case: None }, pair: None }, icu_list::provider::ListFormatterPatterns { start: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b"\xE3\x80\x81") }, 3u8), middle: unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b"\xE3\x80\x81") }, end: icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b"\xE3\x80\x81") }, 3u8), special_case: None }, pair: None }, icu_list::provider::ListFormatterPatterns { start: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b"\xE3\x80\x81") }, 3u8), middle: unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b"\xE3\x80\x81") }, end: icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b"\xE5\x92\x8C") }, 3u8), special_case: None }, pair: Some(icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b"\xE3\x80\x81") }, 3u8), special_case: None }) }, icu_list::provider::ListFormatterPatterns { start: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b", ") }, 2u8), middle: unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b", ") }, end: icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b", & ") }, 4u8), special_case: None }, pair: Some(icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b" & ") }, 3u8), special_case: None }) }, icu_list::provider::ListFormatterPatterns { start: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b", ") }, 2u8), middle: unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b", ") }, end: icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b" et ") }, 4u8), special_case: None }, pair: None }, icu_list::provider::ListFormatterPatterns { start: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b", ") }, 2u8), middle: unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b", ") }, end: icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b" \xD0\xB8 ") }, 4u8), special_case: None }, pair: None }, icu_list::provider::ListFormatterPatterns { start: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b", ") }, 2u8), middle: unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b", ") }, end: icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b" ve ") }, 4u8), special_case: None }, pair: None }, icu_list::provider::ListFormatterPatterns { start: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b"\xE3\x80\x81") }, 3u8), middle: unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b"\xE3\x80\x81") }, end: icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b"\xE5\x92\x8C") }, 3u8), special_case: None }, pair: None }, icu_list::provider::ListFormatterPatterns { start: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b", ") }, 2u8), middle: unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b", ") }, end: icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b", and ") }, 6u8), special_case: None }, pair: Some(icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(unsafe { zerovec::VarZeroCow::from_bytes_unchecked(b" and ") }, 5u8), special_case: None }) }];
+                unsafe { icu_provider::baked::zerotrie::Data::from_trie_and_values_unchecked(TRIE, VALUES) }
+            };
+        }
+        #[clippy::msrv = "1.82"]
+        impl icu_provider::DataProvider<icu_list::provider::ListAndV1> for $provider {
+            fn load(&self, req: icu_provider::DataRequest) -> Result<icu_provider::DataResponse<icu_list::provider::ListAndV1>, icu_provider::DataError> {
+                let mut metadata = icu_provider::DataResponseMetadata::default();
+                let payload = if let Some(payload) = icu_provider::baked::DataStore::get(&Self::DATA_LIST_AND_V1, req.id, req.metadata.attributes_prefix_match) {
+                    payload
+                } else {
+                    const FALLBACKER: icu_locale::fallback::LocaleFallbackerWithConfig<'static> = icu_locale::fallback::LocaleFallbacker::new().for_config(<icu_list::provider::ListAndV1 as icu_provider::DataMarker>::INFO.fallback_config);
+                    let mut fallback_iterator = FALLBACKER.fallback_for(req.id.locale.clone());
+                    loop {
+                        if let Some(payload) = icu_provider::baked::DataStore::get(&Self::DATA_LIST_AND_V1, icu_provider::DataIdentifierBorrowed::for_marker_attributes_and_locale(req.id.marker_attributes, fallback_iterator.get()), req.metadata.attributes_prefix_match) {
+                            metadata.locale = Some(fallback_iterator.take());
+                            break payload;
+                        }
+                        if fallback_iterator.get().is_unknown() {
+                            return Err(icu_provider::DataErrorKind::IdentifierNotFound.with_req(<icu_list::provider::ListAndV1 as icu_provider::DataMarker>::INFO, req));
+                        }
+                        fallback_iterator.step();
+                    }
+                };
+                Ok(icu_provider::DataResponse { payload, metadata })
+            }
+        }
+    };
+    ($ provider : ty , ITER) => {
+        __impl_list_and_v1!($provider);
+        #[clippy::msrv = "1.82"]
+        impl icu_provider::IterableDataProvider<icu_list::provider::ListAndV1> for $provider {
+            fn iter_ids(&self) -> Result<std::collections::BTreeSet<icu_provider::DataIdentifierCow<'static>>, icu_provider::DataError> {
+                Ok(icu_provider::baked::DataStore::iter(&Self::DATA_LIST_AND_V1).collect())
+            }
+        }
+    };
+    ($ provider : ty , DRY) => {};
+    ($ provider : ty , DRY , ITER) => {
+        __impl_list_and_v1!($provider, ITER);
+    };
+}
+#[doc(inline)]
+pub use __impl_list_and_v1 as impl_list_and_v1;
diff --git a/compiler/rustc_baked_icu_data/src/data/macros.rs b/compiler/rustc_baked_icu_data/src/data/macros.rs
deleted file mode 100644
index bee309f9b81..00000000000
--- a/compiler/rustc_baked_icu_data/src/data/macros.rs
+++ /dev/null
@@ -1,46 +0,0 @@
-// @generated
-/// Marks a type as a data provider. You can then use macros like
-/// `impl_core_helloworld_v1` to add implementations.
-///
-/// ```ignore
-/// struct MyProvider;
-/// const _: () = {
-///     include!("path/to/generated/macros.rs");
-///     make_provider!(MyProvider);
-///     impl_core_helloworld_v1!(MyProvider);
-/// }
-/// ```
-#[doc(hidden)]
-#[macro_export]
-macro_rules! __make_provider {
-    ($ name : ty) => {
-        #[clippy::msrv = "1.66"]
-        impl $name {
-            #[doc(hidden)]
-            #[allow(dead_code)]
-            pub const MUST_USE_MAKE_PROVIDER_MACRO: () = ();
-        }
-    };
-}
-#[doc(inline)]
-pub use __make_provider as make_provider;
-#[macro_use]
-#[path = "macros/fallback_likelysubtags_v1.data.rs"]
-mod fallback_likelysubtags_v1;
-#[doc(inline)]
-pub use __impl_fallback_likelysubtags_v1 as impl_fallback_likelysubtags_v1;
-#[macro_use]
-#[path = "macros/fallback_parents_v1.data.rs"]
-mod fallback_parents_v1;
-#[doc(inline)]
-pub use __impl_fallback_parents_v1 as impl_fallback_parents_v1;
-#[macro_use]
-#[path = "macros/fallback_supplement_co_v1.data.rs"]
-mod fallback_supplement_co_v1;
-#[doc(inline)]
-pub use __impl_fallback_supplement_co_v1 as impl_fallback_supplement_co_v1;
-#[macro_use]
-#[path = "macros/list_and_v1.data.rs"]
-mod list_and_v1;
-#[doc(inline)]
-pub use __impl_list_and_v1 as impl_list_and_v1;
diff --git a/compiler/rustc_baked_icu_data/src/data/macros/fallback_likelysubtags_v1.data.rs b/compiler/rustc_baked_icu_data/src/data/macros/fallback_likelysubtags_v1.data.rs
deleted file mode 100644
index 1adb58743f7..00000000000
--- a/compiler/rustc_baked_icu_data/src/data/macros/fallback_likelysubtags_v1.data.rs
+++ /dev/null
@@ -1,40 +0,0 @@
-// @generated
-/// Implement `DataProvider<LocaleFallbackLikelySubtagsV1Marker>` on the given struct using the data
-/// hardcoded in this file. This allows the struct to be used with
-/// `icu`'s `_unstable` constructors.
-#[doc(hidden)]
-#[macro_export]
-macro_rules! __impl_fallback_likelysubtags_v1 {
-    ($ provider : ty) => {
-        #[clippy::msrv = "1.66"]
-        const _: () = <$provider>::MUST_USE_MAKE_PROVIDER_MACRO;
-        #[clippy::msrv = "1.66"]
-        impl $provider {
-            #[doc(hidden)]
-            pub const SINGLETON_FALLBACK_LIKELYSUBTAGS_V1: &'static <icu_locid_transform::provider::LocaleFallbackLikelySubtagsV1Marker as icu_provider::DataMarker>::Yokeable = &icu_locid_transform::provider::LocaleFallbackLikelySubtagsV1 {
-                l2s: unsafe {
-                    #[allow(unused_unsafe)]
-                    zerovec::ZeroMap::from_parts_unchecked(unsafe { zerovec::ZeroVec::from_bytes_unchecked(b"am\0ar\0as\0be\0bg\0bgcbhobn\0brxchrcv\0doiel\0fa\0gu\0he\0hi\0hy\0ja\0ka\0kk\0km\0kn\0ko\0kokks\0ky\0lo\0maimk\0ml\0mn\0mnimr\0my\0ne\0or\0pa\0ps\0rajru\0sa\0satsd\0si\0sr\0ta\0te\0tg\0th\0ti\0tt\0uk\0ur\0yuezh\0") }, unsafe { zerovec::ZeroVec::from_bytes_unchecked(b"EthiArabBengCyrlCyrlDevaDevaBengDevaCherCyrlDevaGrekArabGujrHebrDevaArmnJpanGeorCyrlKhmrKndaKoreDevaArabCyrlLaooDevaCyrlMlymCyrlBengDevaMymrDevaOryaGuruArabDevaCyrlDevaOlckArabSinhCyrlTamlTeluCyrlThaiEthiCyrlCyrlArabHantHans") })
-                },
-                lr2s: unsafe {
-                    #[allow(unused_unsafe)]
-                    zerovec::ZeroMap2d::from_parts_unchecked(unsafe { zerovec::ZeroVec::from_bytes_unchecked(b"az\0ha\0kk\0ky\0mn\0ms\0pa\0sd\0sr\0tg\0uz\0yuezh\0") }, unsafe { zerovec::ZeroVec::from_bytes_unchecked(b"\x03\0\0\0\x05\0\0\0\t\0\0\0\x0B\0\0\0\x0C\0\0\0\r\0\0\0\x0E\0\0\0\x0F\0\0\0\x13\0\0\0\x14\0\0\0\x16\0\0\0\x17\0\0\0&\0\0\0") }, unsafe { zerovec::ZeroVec::from_bytes_unchecked(b"IQ\0IR\0RU\0CM\0SD\0AF\0CN\0IR\0MN\0CN\0TR\0CN\0CC\0PK\0IN\0ME\0RO\0RU\0TR\0PK\0AF\0CN\0CN\0AU\0BN\0GB\0GF\0HK\0ID\0MO\0PA\0PF\0PH\0SR\0TH\0TW\0US\0VN\0") }, unsafe { zerovec::ZeroVec::from_bytes_unchecked(b"ArabArabCyrlArabArabArabArabArabArabArabLatnMongArabArabDevaLatnLatnLatnLatnArabArabCyrlHansHantHantHantHantHantHantHantHantHantHantHantHantHantHantHant") })
-                },
-                l2r: unsafe {
-                    #[allow(unused_unsafe)]
-                    zerovec::ZeroMap::from_parts_unchecked(unsafe { zerovec::ZeroVec::from_bytes_unchecked(b"af\0am\0ar\0as\0astaz\0be\0bg\0bgcbhobn\0br\0brxbs\0ca\0cebchrcs\0cv\0cy\0da\0de\0doidsbel\0en\0es\0et\0eu\0fa\0ff\0fi\0filfo\0fr\0ga\0gd\0gl\0gu\0ha\0he\0hi\0hr\0hsbhu\0hy\0ia\0id\0ig\0is\0it\0ja\0jv\0ka\0keakgpkk\0km\0kn\0ko\0kokks\0ky\0lo\0lt\0lv\0maimi\0mk\0ml\0mn\0mnimr\0ms\0my\0ne\0nl\0nn\0no\0or\0pa\0pcmpl\0ps\0pt\0qu\0rajrm\0ro\0ru\0sa\0satsc\0sd\0si\0sk\0sl\0so\0sq\0sr\0su\0sv\0sw\0ta\0te\0tg\0th\0ti\0tk\0to\0tr\0tt\0uk\0ur\0uz\0vi\0wo\0xh\0yo\0yrlyuezh\0zu\0") }, unsafe { zerovec::ZeroVec::from_bytes_unchecked(b"ZA\0ET\0EG\0IN\0ES\0AZ\0BY\0BG\0IN\0IN\0BD\0FR\0IN\0BA\0ES\0PH\0US\0CZ\0RU\0GB\0DK\0DE\0IN\0DE\0GR\0US\0ES\0EE\0ES\0IR\0SN\0FI\0PH\0FO\0FR\0IE\0GB\0ES\0IN\0NG\0IL\0IN\0HR\0DE\0HU\0AM\x00001ID\0NG\0IS\0IT\0JP\0ID\0GE\0CV\0BR\0KZ\0KH\0IN\0KR\0IN\0IN\0KG\0LA\0LT\0LV\0IN\0NZ\0MK\0IN\0MN\0IN\0IN\0MY\0MM\0NP\0NL\0NO\0NO\0IN\0IN\0NG\0PL\0AF\0BR\0PE\0IN\0CH\0RO\0RU\0IN\0IN\0IT\0PK\0LK\0SK\0SI\0SO\0AL\0RS\0ID\0SE\0TZ\0IN\0IN\0TJ\0TH\0ET\0TM\0TO\0TR\0RU\0UA\0PK\0UZ\0VN\0SN\0ZA\0NG\0BR\0HK\0CN\0ZA\0") })
-                },
-                ls2r: unsafe {
-                    #[allow(unused_unsafe)]
-                    zerovec::ZeroMap2d::from_parts_unchecked(unsafe { zerovec::ZeroVec::from_bytes_unchecked(b"az\0en\0ff\0kk\0ky\0mn\0pa\0sd\0tg\0uz\0yuezh\0") }, unsafe { zerovec::ZeroVec::from_bytes_unchecked(b"\x01\0\0\0\x02\0\0\0\x03\0\0\0\x04\0\0\0\x06\0\0\0\x07\0\0\0\x08\0\0\0\x0B\0\0\0\x0C\0\0\0\r\0\0\0\x0E\0\0\0\x11\0\0\0") }, unsafe { zerovec::ZeroVec::from_bytes_unchecked(b"ArabShawAdlmArabArabLatnMongArabDevaKhojSindArabArabHansBopoHanbHant") }, unsafe { zerovec::ZeroVec::from_bytes_unchecked(b"IR\0GB\0GN\0CN\0CN\0TR\0CN\0PK\0IN\0IN\0IN\0PK\0AF\0CN\0TW\0TW\0TW\0") })
-                },
-            };
-        }
-        #[clippy::msrv = "1.66"]
-        impl icu_provider::DataProvider<icu_locid_transform::provider::LocaleFallbackLikelySubtagsV1Marker> for $provider {
-            fn load(&self, req: icu_provider::DataRequest) -> Result<icu_provider::DataResponse<icu_locid_transform::provider::LocaleFallbackLikelySubtagsV1Marker>, icu_provider::DataError> {
-                if req.locale.is_empty() { Ok(icu_provider::DataResponse { payload: Some(icu_provider::DataPayload::from_static_ref(Self::SINGLETON_FALLBACK_LIKELYSUBTAGS_V1)), metadata: Default::default() }) } else { Err(icu_provider::DataErrorKind::ExtraneousLocale.with_req(<icu_locid_transform::provider::LocaleFallbackLikelySubtagsV1Marker as icu_provider::KeyedDataMarker>::KEY, req)) }
-            }
-        }
-    };
-}
diff --git a/compiler/rustc_baked_icu_data/src/data/macros/fallback_parents_v1.data.rs b/compiler/rustc_baked_icu_data/src/data/macros/fallback_parents_v1.data.rs
deleted file mode 100644
index 6f8d6590b08..00000000000
--- a/compiler/rustc_baked_icu_data/src/data/macros/fallback_parents_v1.data.rs
+++ /dev/null
@@ -1,28 +0,0 @@
-// @generated
-/// Implement `DataProvider<LocaleFallbackParentsV1Marker>` on the given struct using the data
-/// hardcoded in this file. This allows the struct to be used with
-/// `icu`'s `_unstable` constructors.
-#[doc(hidden)]
-#[macro_export]
-macro_rules! __impl_fallback_parents_v1 {
-    ($ provider : ty) => {
-        #[clippy::msrv = "1.66"]
-        const _: () = <$provider>::MUST_USE_MAKE_PROVIDER_MACRO;
-        #[clippy::msrv = "1.66"]
-        impl $provider {
-            #[doc(hidden)]
-            pub const SINGLETON_FALLBACK_PARENTS_V1: &'static <icu_locid_transform::provider::LocaleFallbackParentsV1Marker as icu_provider::DataMarker>::Yokeable = &icu_locid_transform::provider::LocaleFallbackParentsV1 {
-                parents: unsafe {
-                    #[allow(unused_unsafe)]
-                    zerovec::ZeroMap::from_parts_unchecked(unsafe { zerovec::VarZeroVec::from_bytes_unchecked(b"\x84\0\0\0\0\0\x06\0\x0B\0\x10\0\x15\0\x1A\0\x1F\0$\0)\0.\x003\08\0=\0B\0G\0L\0Q\0V\0[\0`\0e\0j\0o\0t\0y\0~\0\x83\0\x88\0\x8D\0\x92\0\x97\0\x9C\0\xA1\0\xA6\0\xAB\0\xB0\0\xB5\0\xBA\0\xBF\0\xC4\0\xC9\0\xCE\0\xD3\0\xD8\0\xDD\0\xE2\0\xE7\0\xEC\0\xF1\0\xF6\0\xFB\0\0\x01\x05\x01\n\x01\x0F\x01\x14\x01\x19\x01\x1E\x01#\x01(\x01-\x012\x017\x01<\x01A\x01F\x01K\x01P\x01U\x01Z\x01_\x01d\x01i\x01n\x01s\x01x\x01}\x01\x82\x01\x87\x01\x8C\x01\x91\x01\x96\x01\x9B\x01\xA0\x01\xA5\x01\xAA\x01\xAF\x01\xB4\x01\xB9\x01\xBE\x01\xC3\x01\xC8\x01\xCD\x01\xD2\x01\xD7\x01\xDC\x01\xE1\x01\xE6\x01\xEB\x01\xF0\x01\xF5\x01\xFA\x01\xFF\x01\x04\x02\t\x02\x0E\x02\x13\x02\x18\x02\x1D\x02\"\x02'\x02,\x021\x026\x02;\x02@\x02G\x02I\x02K\x02M\x02R\x02W\x02\\\x02a\x02f\x02k\x02p\x02u\x02z\x02\x7F\x02\x84\x02\x89\x02en-150en-AGen-AIen-ATen-AUen-BBen-BEen-BMen-BSen-BWen-BZen-CCen-CHen-CKen-CMen-CXen-CYen-DEen-DGen-DKen-DMen-ERen-FIen-FJen-FKen-FMen-GBen-GDen-GGen-GHen-GIen-GMen-GYen-HKen-IEen-ILen-IMen-INen-IOen-JEen-JMen-KEen-KIen-KNen-KYen-LCen-LRen-LSen-MGen-MOen-MSen-MTen-MUen-MVen-MWen-MYen-NAen-NFen-NGen-NLen-NRen-NUen-NZen-PGen-PKen-PNen-PWen-RWen-SBen-SCen-SDen-SEen-SGen-SHen-SIen-SLen-SSen-SXen-SZen-TCen-TKen-TOen-TTen-TVen-TZen-UGen-VCen-VGen-VUen-WSen-ZAen-ZMen-ZWes-ARes-BOes-BRes-BZes-CLes-COes-CRes-CUes-DOes-ECes-GTes-HNes-MXes-NIes-PAes-PEes-PRes-PYes-SVes-USes-UYes-VEhi-Latnhtnbnnno-NOpt-AOpt-CHpt-CVpt-FRpt-GQpt-GWpt-LUpt-MOpt-MZpt-STpt-TLzh-Hant-MO") }, unsafe { zerovec::ZeroVec::from_bytes_unchecked(b"en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01150en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01150en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01150en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01150en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01150en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01150en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01150en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01150en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01150en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001en\0\0\0\0\0\0\x01001es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419es\0\0\0\0\0\0\x01419en\0\0\0\0\0\0\x01IN\0fr\0\0\0\0\0\0\x01HT\0no\0\0\0\0\0\0\0\0\0\0no\0\0\0\0\0\0\0\0\0\0no\0\0\0\0\0\0\0\0\0\0pt\0\0\0\0\0\0\x01PT\0pt\0\0\0\0\0\0\x01PT\0pt\0\0\0\0\0\0\x01PT\0pt\0\0\0\0\0\0\x01PT\0pt\0\0\0\0\0\0\x01PT\0pt\0\0\0\0\0\0\x01PT\0pt\0\0\0\0\0\0\x01PT\0pt\0\0\0\0\0\0\x01PT\0pt\0\0\0\0\0\0\x01PT\0pt\0\0\0\0\0\0\x01PT\0pt\0\0\0\0\0\0\x01PT\0zh\0\x01Hant\x01HK\0") })
-                },
-            };
-        }
-        #[clippy::msrv = "1.66"]
-        impl icu_provider::DataProvider<icu_locid_transform::provider::LocaleFallbackParentsV1Marker> for $provider {
-            fn load(&self, req: icu_provider::DataRequest) -> Result<icu_provider::DataResponse<icu_locid_transform::provider::LocaleFallbackParentsV1Marker>, icu_provider::DataError> {
-                if req.locale.is_empty() { Ok(icu_provider::DataResponse { payload: Some(icu_provider::DataPayload::from_static_ref(Self::SINGLETON_FALLBACK_PARENTS_V1)), metadata: Default::default() }) } else { Err(icu_provider::DataErrorKind::ExtraneousLocale.with_req(<icu_locid_transform::provider::LocaleFallbackParentsV1Marker as icu_provider::KeyedDataMarker>::KEY, req)) }
-            }
-        }
-    };
-}
diff --git a/compiler/rustc_baked_icu_data/src/data/macros/fallback_supplement_co_v1.data.rs b/compiler/rustc_baked_icu_data/src/data/macros/fallback_supplement_co_v1.data.rs
deleted file mode 100644
index 02eec37ee09..00000000000
--- a/compiler/rustc_baked_icu_data/src/data/macros/fallback_supplement_co_v1.data.rs
+++ /dev/null
@@ -1,32 +0,0 @@
-// @generated
-/// Implement `DataProvider<CollationFallbackSupplementV1Marker>` on the given struct using the data
-/// hardcoded in this file. This allows the struct to be used with
-/// `icu`'s `_unstable` constructors.
-#[doc(hidden)]
-#[macro_export]
-macro_rules! __impl_fallback_supplement_co_v1 {
-    ($ provider : ty) => {
-        #[clippy::msrv = "1.66"]
-        const _: () = <$provider>::MUST_USE_MAKE_PROVIDER_MACRO;
-        #[clippy::msrv = "1.66"]
-        impl $provider {
-            #[doc(hidden)]
-            pub const SINGLETON_FALLBACK_SUPPLEMENT_CO_V1: &'static <icu_locid_transform::provider::CollationFallbackSupplementV1Marker as icu_provider::DataMarker>::Yokeable = &icu_locid_transform::provider::LocaleFallbackSupplementV1 {
-                parents: unsafe {
-                    #[allow(unused_unsafe)]
-                    zerovec::ZeroMap::from_parts_unchecked(unsafe { zerovec::VarZeroVec::from_bytes_unchecked(b"\x01\0\0\0\0\0yue") }, unsafe { zerovec::ZeroVec::from_bytes_unchecked(b"zh\0\x01Hant\0\0\0\0") })
-                },
-                unicode_extension_defaults: unsafe {
-                    #[allow(unused_unsafe)]
-                    zerovec::ZeroMap2d::from_parts_unchecked(unsafe { zerovec::ZeroVec::from_bytes_unchecked(b"co") }, unsafe { zerovec::ZeroVec::from_bytes_unchecked(b"\x02\0\0\0") }, unsafe { zerovec::VarZeroVec::from_bytes_unchecked(b"\x02\0\0\0\0\0\x02\0zhzh-Hant") }, unsafe { zerovec::VarZeroVec::from_bytes_unchecked(b"\x02\0\0\0\0\0\x06\0pinyinstroke") })
-                },
-            };
-        }
-        #[clippy::msrv = "1.66"]
-        impl icu_provider::DataProvider<icu_locid_transform::provider::CollationFallbackSupplementV1Marker> for $provider {
-            fn load(&self, req: icu_provider::DataRequest) -> Result<icu_provider::DataResponse<icu_locid_transform::provider::CollationFallbackSupplementV1Marker>, icu_provider::DataError> {
-                if req.locale.is_empty() { Ok(icu_provider::DataResponse { payload: Some(icu_provider::DataPayload::from_static_ref(Self::SINGLETON_FALLBACK_SUPPLEMENT_CO_V1)), metadata: Default::default() }) } else { Err(icu_provider::DataErrorKind::ExtraneousLocale.with_req(<icu_locid_transform::provider::CollationFallbackSupplementV1Marker as icu_provider::KeyedDataMarker>::KEY, req)) }
-            }
-        }
-    };
-}
diff --git a/compiler/rustc_baked_icu_data/src/data/macros/list_and_v1.data.rs b/compiler/rustc_baked_icu_data/src/data/macros/list_and_v1.data.rs
deleted file mode 100644
index 186f706cdb2..00000000000
--- a/compiler/rustc_baked_icu_data/src/data/macros/list_and_v1.data.rs
+++ /dev/null
@@ -1,35 +0,0 @@
-// @generated
-/// Implement `DataProvider<AndListV1Marker>` on the given struct using the data
-/// hardcoded in this file. This allows the struct to be used with
-/// `icu`'s `_unstable` constructors.
-#[doc(hidden)]
-#[macro_export]
-macro_rules! __impl_list_and_v1 {
-    ($ provider : ty) => {
-        #[clippy::msrv = "1.66"]
-        const _: () = <$provider>::MUST_USE_MAKE_PROVIDER_MACRO;
-        #[clippy::msrv = "1.66"]
-        impl icu_provider::DataProvider<icu_list::provider::AndListV1Marker> for $provider {
-            fn load(&self, req: icu_provider::DataRequest) -> Result<icu_provider::DataResponse<icu_list::provider::AndListV1Marker>, icu_provider::DataError> {
-                static EN_001: <icu_list::provider::AndListV1Marker as icu_provider::DataMarker>::Yokeable = icu_list::provider::ListFormatterPatternsV1([icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" and ", 5u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" and ", 5u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" and ", 5u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" and ", 5u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }]);
-                static EN_IN: <icu_list::provider::AndListV1Marker as icu_provider::DataMarker>::Yokeable = icu_list::provider::ListFormatterPatternsV1([icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" and ", 5u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" and ", 5u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" and ", 5u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" and ", 5u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", and ", 6u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }]);
-                static IT: <icu_list::provider::AndListV1Marker as icu_provider::DataMarker>::Yokeable = icu_list::provider::ListFormatterPatternsV1([icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" e ", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" e ", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" e ", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" e ", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" e ", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" e ", 3u8), special_case: None }]);
-                static PT: <icu_list::provider::AndListV1Marker as icu_provider::DataMarker>::Yokeable = icu_list::provider::ListFormatterPatternsV1([icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" e ", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" e ", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" e ", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" e ", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }]);
-                static FR: <icu_list::provider::AndListV1Marker as icu_provider::DataMarker>::Yokeable = icu_list::provider::ListFormatterPatternsV1([icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" et ", 4u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" et ", 4u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" et ", 4u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" et ", 4u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }]);
-                static TR: <icu_list::provider::AndListV1Marker as icu_provider::DataMarker>::Yokeable = icu_list::provider::ListFormatterPatternsV1([icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" ve ", 4u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" ve ", 4u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" ve ", 4u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" ve ", 4u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }]);
-                static ES: <icu_list::provider::AndListV1Marker as icu_provider::DataMarker>::Yokeable = icu_list::provider::ListFormatterPatternsV1([icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" y ", 3u8), special_case: Some(icu_list::provider::SpecialCasePattern { condition: unsafe { icu_list::provider::SerdeDFA::from_dfa_bytes_unchecked(if cfg!(target_endian = "little") { b"rust-regex-automata-dfa-sparse\0\0\xFF\xFE\0\0\x02\0\0\0\0\0\0\0\x0E\0\0\0\x01\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\x01\x02\x02\x02\x03\x04\x04\x05\x06\x07\x07\x07\x07\x07\x07\x07\x07\x07\x07\x07\x07\x07\x07\x07\x07\x07\x07\x07\x07\x07\x07\x07\x08\t\t\t\n\x0B\x0B\x0C\r\x0E\x0E\x0E\x0E\x0E\x0E\x0E\x0E\x0E\x0E\x0E\x0E\x0E\x0E\x0E\x0E\x0E\x0E\x0E\x0E\x0E\x0E\x0F\x0F\x0F\x0F\x0F\x0F\x0F\x0F\x0F\x0F\x0F\x0F\x0F\x0F\x0F\x0F\x10\x10\x10\x10\x10\x10\x10\x10\x10\x10\x10\x10\x10\x10\x10\x10\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x12\x12\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x13\x14\x15\x15\x15\x15\x15\x15\x15\x15\x15\x15\x15\x15\x16\x17\x17\x18\x19\x19\x19\x1A\x1B\x1B\x1B\x1B\x1B\x1B\x1B\x1B\x1B\x1B\x1B(\x01\0\0\x01\0\0\0\0\0\0\0\0\x01\0\0\0\0\0\0\0\0\x01\x80\0\0\0\0\0\0\x01\0\0\0\0\0\0\0\0\x05\0\x05\x05\x06\x06\x0C\x0C\r\r\0\0S\0\0\0D\0\0\0S\0\0\0D\0\0\0\0\0\0\0\0\x02\0\0\x1B\0\0\x12\0\0\0\x12\0\0\0\0\x03\0\x06\x06\r\r\0\0h\0\0\0h\0\0\0\0\0\0\0\0\x0E\0\0\0\x02\x02\x04\x07\t\t\x0B\x0E\x13\x13\x14\x14\x15\x15\x16\x16\x17\x17\x18\x18\x19\x19\x1A\x1A\0\0D\0\0\0D\0\0\0D\0\0\0D\0\0\0D\0\0\0\xBF\0\0\0\xCE\0\0\0\xDD\0\0\0\xEC\0\0\0\xDD\0\0\0\xFB\0\0\0\n\x01\0\0\x19\x01\0\0\x12\0\0\0\0\x02\0\x0F\x11\0\0D\0\0\0\0\0\0\0\0\x02\0\x11\x11\0\0\xBF\0\0\0\0\0\0\0\0\x02\0\x0F\x11\0\0\xBF\0\0\0\0\0\0\0\0\x02\0\x0F\x10\0\0\xBF\0\0\0\0\0\0\0\0\x02\0\x10\x11\0\0\xDD\0\0\0\0\0\0\0\0\x02\0\x0F\x11\0\0\xDD\0\0\0\0\0\0\0\0\x02\0\x0F\x0F\0\0\xDD\0\0\0\0\0\0\0\0\x04\0\0\0\0\0\0\0#\0\0\0#\0\0\0#\0\0\0#\0\0\0#\0\0\0\t\0\0\0\x12\0\0\0\x12\0\0\0\0\0\0\0\0\0\0\0#\0\0\0#\0\0\0" } else { 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}) }, pattern: icu_list::provider::ListJoinerPattern::from_parts(" e ", 3u8) }) }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" y ", 3u8), special_case: Some(icu_list::provider::SpecialCasePattern { condition: unsafe { icu_list::provider::SerdeDFA::from_dfa_bytes_unchecked(if cfg!(target_endian = "little") { 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} else { 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}) }, pattern: icu_list::provider::ListJoinerPattern::from_parts(" e ", 3u8) }) }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" y ", 3u8), special_case: Some(icu_list::provider::SpecialCasePattern { condition: unsafe { icu_list::provider::SerdeDFA::from_dfa_bytes_unchecked(if cfg!(target_endian = "little") { 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} else { 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}) }, pattern: icu_list::provider::ListJoinerPattern::from_parts(" e ", 3u8) }) }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" y ", 3u8), special_case: Some(icu_list::provider::SpecialCasePattern { condition: unsafe { icu_list::provider::SerdeDFA::from_dfa_bytes_unchecked(if cfg!(target_endian = "little") { 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} else { 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}) }, pattern: icu_list::provider::ListJoinerPattern::from_parts(" e ", 3u8) }) }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" y ", 3u8), special_case: Some(icu_list::provider::SpecialCasePattern { condition: unsafe { icu_list::provider::SerdeDFA::from_dfa_bytes_unchecked(if cfg!(target_endian = "little") { 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} else { 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}) }, pattern: icu_list::provider::ListJoinerPattern::from_parts(" e ", 3u8) }) }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" y ", 3u8), special_case: Some(icu_list::provider::SpecialCasePattern { condition: unsafe { icu_list::provider::SerdeDFA::from_dfa_bytes_unchecked(if cfg!(target_endian = "little") { 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} else { 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}) }, pattern: icu_list::provider::ListJoinerPattern::from_parts(" e ", 3u8) }) }]);
-                static RU: <icu_list::provider::AndListV1Marker as icu_provider::DataMarker>::Yokeable = icu_list::provider::ListFormatterPatternsV1([icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" и ", 4u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" и ", 4u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" и ", 4u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" и ", 4u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }]);
-                static UND: <icu_list::provider::AndListV1Marker as icu_provider::DataMarker>::Yokeable = icu_list::provider::ListFormatterPatternsV1([icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }]);
-                static EN: <icu_list::provider::AndListV1Marker as icu_provider::DataMarker>::Yokeable = icu_list::provider::ListFormatterPatternsV1([icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", and ", 6u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" and ", 5u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", & ", 4u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" & ", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }]);
-                static HI_LATN: <icu_list::provider::AndListV1Marker as icu_provider::DataMarker>::Yokeable = icu_list::provider::ListFormatterPatternsV1([icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", aur ", 6u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" aur ", 5u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", aur ", 6u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" aur ", 5u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(", ", 2u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts(" aur ", 5u8), special_case: None }]);
-                static JA: <icu_list::provider::AndListV1Marker as icu_provider::DataMarker>::Yokeable = icu_list::provider::ListFormatterPatternsV1([icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }]);
-                static ZH_HK: <icu_list::provider::AndListV1Marker as icu_provider::DataMarker>::Yokeable = icu_list::provider::ListFormatterPatternsV1([icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("及", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("及", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("及", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("及", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("及", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("及", 3u8), special_case: None }]);
-                static ZH: <icu_list::provider::AndListV1Marker as icu_provider::DataMarker>::Yokeable = icu_list::provider::ListFormatterPatternsV1([icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("和", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("和", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("和", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("和", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }]);
-                static ZH_HANT: <icu_list::provider::AndListV1Marker as icu_provider::DataMarker>::Yokeable = icu_list::provider::ListFormatterPatternsV1([icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("和", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("和", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("和", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("和", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("、", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("和", 3u8), special_case: None }, icu_list::provider::ConditionalListJoinerPattern { default: icu_list::provider::ListJoinerPattern::from_parts("和", 3u8), special_case: None }]);
-                static VALUES: [&<icu_list::provider::AndListV1Marker as icu_provider::DataMarker>::Yokeable; 215usize] = [&EN, &EN_001, &EN_001, &EN, &EN_001, &EN_001, &EN, &EN_001, &EN_001, &EN_001, &EN_001, &EN, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_IN, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN, &EN_001, &EN, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN, &EN_001, &EN_001, &EN, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &EN, &EN_001, &EN_001, &EN, &EN_001, &EN_001, &EN_001, &EN_001, &EN_001, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &ES, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &FR, &HI_LATN, &IT, &IT, &IT, &IT, &JA, &PT, &PT, &PT, &PT, &PT, &PT, &PT, &PT, &PT, &PT, &PT, &PT, &RU, &RU, &RU, &RU, &RU, &RU, &TR, &TR, &UND, &ZH, &ZH_HK, &ZH, &ZH, &ZH, &ZH_HANT, &ZH_HK, &ZH];
-                static KEYS: [&str; 215usize] = ["en", "en-001", "en-150", "en-AE", "en-AG", "en-AI", "en-AS", "en-AT", "en-AU", "en-BB", "en-BE", "en-BI", "en-BM", "en-BS", "en-BW", "en-BZ", "en-CA", "en-CC", "en-CH", "en-CK", "en-CM", "en-CX", "en-CY", "en-DE", "en-DG", "en-DK", "en-DM", "en-ER", "en-FI", "en-FJ", "en-FK", "en-FM", "en-GB", "en-GD", "en-GG", "en-GH", "en-GI", "en-GM", "en-GU", "en-GY", "en-HK", "en-IE", "en-IL", "en-IM", "en-IN", "en-IO", "en-JE", "en-JM", "en-KE", "en-KI", "en-KN", "en-KY", "en-LC", "en-LR", "en-LS", "en-MG", "en-MH", "en-MO", "en-MP", "en-MS", "en-MT", "en-MU", "en-MV", "en-MW", "en-MY", "en-NA", "en-NF", "en-NG", "en-NL", "en-NR", "en-NU", "en-NZ", "en-PG", "en-PH", "en-PK", "en-PN", "en-PR", "en-PW", "en-RW", "en-SB", "en-SC", "en-SD", "en-SE", "en-SG", "en-SH", "en-SI", "en-SL", "en-SS", "en-SX", "en-SZ", "en-TC", "en-TK", "en-TO", "en-TT", "en-TV", "en-TZ", "en-UG", "en-UM", "en-VC", "en-VG", "en-VI", "en-VU", "en-WS", "en-ZA", "en-ZM", "en-ZW", "es", "es-419", "es-AR", "es-BO", "es-BR", "es-BZ", "es-CL", "es-CO", "es-CR", "es-CU", "es-DO", "es-EA", "es-EC", "es-GQ", "es-GT", "es-HN", "es-IC", "es-MX", "es-NI", "es-PA", "es-PE", "es-PH", "es-PR", "es-PY", "es-SV", "es-US", "es-UY", "es-VE", "fr", "fr-BE", "fr-BF", "fr-BI", "fr-BJ", "fr-BL", "fr-CA", "fr-CD", "fr-CF", "fr-CG", "fr-CH", "fr-CI", "fr-CM", "fr-DJ", "fr-DZ", "fr-GA", "fr-GF", "fr-GN", "fr-GP", "fr-GQ", "fr-HT", "fr-KM", "fr-LU", "fr-MA", "fr-MC", "fr-MF", "fr-MG", "fr-ML", "fr-MQ", "fr-MR", "fr-MU", "fr-NC", "fr-NE", "fr-PF", "fr-PM", "fr-RE", "fr-RW", "fr-SC", "fr-SN", "fr-SY", "fr-TD", "fr-TG", "fr-TN", "fr-VU", "fr-WF", "fr-YT", "hi-Latn", "it", "it-CH", "it-SM", "it-VA", "ja", "pt", "pt-AO", "pt-CH", "pt-CV", "pt-GQ", "pt-GW", "pt-LU", "pt-MO", "pt-MZ", "pt-PT", "pt-ST", "pt-TL", "ru", "ru-BY", "ru-KG", "ru-KZ", "ru-MD", "ru-UA", "tr", "tr-CY", "und", "zh", "zh-HK", "zh-Hans", "zh-Hans-HK", "zh-Hans-MO", "zh-Hant", "zh-MO", "zh-SG"];
-                if let Ok(payload) = KEYS.binary_search_by(|k| req.locale.strict_cmp(k.as_bytes()).reverse()).map(|i| *unsafe { VALUES.get_unchecked(i) }) { Ok(icu_provider::DataResponse { payload: Some(icu_provider::DataPayload::from_static_ref(payload)), metadata: Default::default() }) } else { Err(icu_provider::DataErrorKind::MissingLocale.with_req(<icu_list::provider::AndListV1Marker as icu_provider::KeyedDataMarker>::KEY, req)) }
-            }
-        }
-    };
-}
diff --git a/compiler/rustc_baked_icu_data/src/data/mod.rs b/compiler/rustc_baked_icu_data/src/data/mod.rs
index 465689f0cb8..3146188a8e7 100644
--- a/compiler/rustc_baked_icu_data/src/data/mod.rs
+++ b/compiler/rustc_baked_icu_data/src/data/mod.rs
@@ -1,31 +1,40 @@
 // @generated
-include!("macros.rs");
-macro_rules! impl_data_provider {
-    ($ provider : ty) => {
-        make_provider!($provider);
-        impl_fallback_likelysubtags_v1!($provider);
-        impl_fallback_parents_v1!($provider);
-        impl_fallback_supplement_co_v1!($provider);
-        impl_list_and_v1!($provider);
+include!("list_and_v1.rs.data");
+/// Marks a type as a data provider. You can then use macros like
+/// `impl_core_helloworld_v1` to add implementations.
+///
+/// ```ignore
+/// struct MyProvider;
+/// const _: () = {
+///     include!("path/to/generated/macros.rs");
+///     make_provider!(MyProvider);
+///     impl_core_helloworld_v1!(MyProvider);
+/// }
+/// ```
+#[doc(hidden)]
+#[macro_export]
+macro_rules! __make_provider {
+    ($ name : ty) => {
+        #[clippy::msrv = "1.82"]
+        impl $name {
+            #[allow(dead_code)]
+            pub(crate) const MUST_USE_MAKE_PROVIDER_MACRO: () = ();
+        }
+        icu_provider::marker::impl_data_provider_never_marker!($name);
     };
 }
+#[doc(inline)]
+pub use __make_provider as make_provider;
+/// This macro requires the following crates:
+/// * `icu_list`
+/// * `icu_locale/compiled_data`
+/// * `icu_provider`
+/// * `icu_provider/baked`
+/// * `zerovec`
 #[allow(unused_macros)]
-macro_rules! impl_any_provider {
+macro_rules! impl_data_provider {
     ($ provider : ty) => {
-        #[clippy::msrv = "1.66"]
-        impl icu_provider::AnyProvider for $provider {
-            fn load_any(&self, key: icu_provider::DataKey, req: icu_provider::DataRequest) -> Result<icu_provider::AnyResponse, icu_provider::DataError> {
-                match key.hashed() {
-                    h if h == <icu_locid_transform::provider::LocaleFallbackLikelySubtagsV1Marker as icu_provider::KeyedDataMarker>::KEY.hashed() => icu_provider::DataProvider::<icu_locid_transform::provider::LocaleFallbackLikelySubtagsV1Marker>::load(self, req).map(icu_provider::DataResponse::wrap_into_any_response),
-                    h if h == <icu_locid_transform::provider::LocaleFallbackParentsV1Marker as icu_provider::KeyedDataMarker>::KEY.hashed() => icu_provider::DataProvider::<icu_locid_transform::provider::LocaleFallbackParentsV1Marker>::load(self, req).map(icu_provider::DataResponse::wrap_into_any_response),
-                    h if h == <icu_locid_transform::provider::CollationFallbackSupplementV1Marker as icu_provider::KeyedDataMarker>::KEY.hashed() => icu_provider::DataProvider::<icu_locid_transform::provider::CollationFallbackSupplementV1Marker>::load(self, req).map(icu_provider::DataResponse::wrap_into_any_response),
-                    h if h == <icu_list::provider::AndListV1Marker as icu_provider::KeyedDataMarker>::KEY.hashed() => icu_provider::DataProvider::<icu_list::provider::AndListV1Marker>::load(self, req).map(icu_provider::DataResponse::wrap_into_any_response),
-                    _ => Err(icu_provider::DataErrorKind::MissingDataKey.with_req(key, req)),
-                }
-            }
-        }
+        make_provider!($provider);
+        impl_list_and_v1!($provider);
     };
 }
-#[clippy::msrv = "1.66"]
-pub struct BakedDataProvider;
-impl_data_provider!(BakedDataProvider);
diff --git a/compiler/rustc_baked_icu_data/src/lib.rs b/compiler/rustc_baked_icu_data/src/lib.rs
index f3f6522f575..ea4c8242c62 100644
--- a/compiler/rustc_baked_icu_data/src/lib.rs
+++ b/compiler/rustc_baked_icu_data/src/lib.rs
@@ -14,10 +14,9 @@
 //! To regenerate the data, run this command:
 //!
 //! ```text
-//! icu4x-datagen -W --pretty --fingerprint --use-separate-crates \
-//! --format mod -l en es fr it ja pt ru tr zh zh-Hans zh-Hant \
-//! -k list/and@1 fallback/likelysubtags@1 fallback/parents@1 fallback/supplement/co@1 \
-//! --cldr-tag latest --icuexport-tag latest -o src/data
+//! icu4x-datagen -W --pretty --use-separate-crates \
+//! --format baked --locales @en @es @fr @it @ja @pt @ru @tr @zh @zh-Hans @zh-Hant \
+//! -m ListAndV1 -o src/data
 //! ```
 
 // tidy-alphabetical-start
@@ -29,26 +28,26 @@
 // #![warn(unreachable_pub)] // don't use because this crate is mostly generated code
 // tidy-alphabetical-end
 
-mod data {
-    include!("data/mod.rs");
-    include!("data/any.rs");
-}
+pub struct BakedDataProvider;
 
-pub use data::BakedDataProvider;
+include!("data/mod.rs");
+const _: () = {
+    impl_data_provider!(BakedDataProvider);
+};
 
 pub const fn baked_data_provider() -> BakedDataProvider {
-    data::BakedDataProvider
+    BakedDataProvider
 }
 
 pub mod supported_locales {
-    pub const EN: icu_locid::Locale = icu_locid::locale!("en");
-    pub const ES: icu_locid::Locale = icu_locid::locale!("es");
-    pub const FR: icu_locid::Locale = icu_locid::locale!("fr");
-    pub const IT: icu_locid::Locale = icu_locid::locale!("it");
-    pub const JA: icu_locid::Locale = icu_locid::locale!("ja");
-    pub const PT: icu_locid::Locale = icu_locid::locale!("pt");
-    pub const RU: icu_locid::Locale = icu_locid::locale!("ru");
-    pub const TR: icu_locid::Locale = icu_locid::locale!("tr");
-    pub const ZH_HANS: icu_locid::Locale = icu_locid::locale!("zh-Hans");
-    pub const ZH_HANT: icu_locid::Locale = icu_locid::locale!("zh-Hant");
+    pub const EN: icu_locale::Locale = icu_locale::locale!("en");
+    pub const ES: icu_locale::Locale = icu_locale::locale!("es");
+    pub const FR: icu_locale::Locale = icu_locale::locale!("fr");
+    pub const IT: icu_locale::Locale = icu_locale::locale!("it");
+    pub const JA: icu_locale::Locale = icu_locale::locale!("ja");
+    pub const PT: icu_locale::Locale = icu_locale::locale!("pt");
+    pub const RU: icu_locale::Locale = icu_locale::locale!("ru");
+    pub const TR: icu_locale::Locale = icu_locale::locale!("tr");
+    pub const ZH_HANS: icu_locale::Locale = icu_locale::locale!("zh-Hans");
+    pub const ZH_HANT: icu_locale::Locale = icu_locale::locale!("zh-Hant");
 }
diff --git a/compiler/rustc_borrowck/Cargo.toml b/compiler/rustc_borrowck/Cargo.toml
index 9e7d55180a2..3162e9da1ba 100644
--- a/compiler/rustc_borrowck/Cargo.toml
+++ b/compiler/rustc_borrowck/Cargo.toml
@@ -6,7 +6,7 @@ edition = "2024"
 [dependencies]
 # tidy-alphabetical-start
 either = "1.5.0"
-itertools = "0.12"
+itertools.workspace = true
 polonius-engine = "0.13.0"
 rustc_abi = { path = "../rustc_abi" }
 rustc_data_structures = { path = "../rustc_data_structures" }
@@ -25,5 +25,5 @@ rustc_span = { path = "../rustc_span" }
 rustc_trait_selection = { path = "../rustc_trait_selection" }
 rustc_traits = { path = "../rustc_traits" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_borrowck/messages.ftl b/compiler/rustc_borrowck/messages.ftl
index 33b80c4b03d..f59e106c7ac 100644
--- a/compiler/rustc_borrowck/messages.ftl
+++ b/compiler/rustc_borrowck/messages.ftl
@@ -90,7 +90,7 @@ borrowck_lifetime_constraints_error =
     lifetime may not live long enough
 
 borrowck_limitations_implies_static =
-    due to current limitations in the borrow checker, this implies a `'static` lifetime
+    due to a current limitation of the type system, this implies a `'static` lifetime
 
 borrowck_move_closure_suggestion =
     consider adding 'move' keyword before the nested closure
diff --git a/compiler/rustc_borrowck/src/dataflow.rs b/compiler/rustc_borrowck/src/dataflow.rs
index 57db2e9fb57..d3f6c01ab8c 100644
--- a/compiler/rustc_borrowck/src/dataflow.rs
+++ b/compiler/rustc_borrowck/src/dataflow.rs
@@ -1,7 +1,6 @@
 use std::fmt;
 
 use rustc_data_structures::fx::FxIndexMap;
-use rustc_data_structures::graph;
 use rustc_index::bit_set::{DenseBitSet, MixedBitSet};
 use rustc_middle::mir::{
     self, BasicBlock, Body, CallReturnPlaces, Location, Place, TerminatorEdges,
@@ -317,9 +316,8 @@ impl<'tcx> PoloniusOutOfScopePrecomputer<'_, 'tcx> {
             loans_out_of_scope_at_location: FxIndexMap::default(),
         };
         for (loan_idx, loan_data) in borrow_set.iter_enumerated() {
-            let issuing_region = loan_data.region;
             let loan_issued_at = loan_data.reserve_location;
-            prec.precompute_loans_out_of_scope(loan_idx, issuing_region, loan_issued_at);
+            prec.precompute_loans_out_of_scope(loan_idx, loan_issued_at);
         }
 
         prec.loans_out_of_scope_at_location
@@ -328,45 +326,7 @@ impl<'tcx> PoloniusOutOfScopePrecomputer<'_, 'tcx> {
     /// Loans are in scope while they are live: whether they are contained within any live region.
     /// In the location-insensitive analysis, a loan will be contained in a region if the issuing
     /// region can reach it in the subset graph. So this is a reachability problem.
-    fn precompute_loans_out_of_scope(
-        &mut self,
-        loan_idx: BorrowIndex,
-        issuing_region: RegionVid,
-        loan_issued_at: Location,
-    ) {
-        let sccs = self.regioncx.constraint_sccs();
-        let universal_regions = self.regioncx.universal_regions();
-
-        // The loop below was useful for the location-insensitive analysis but shouldn't be
-        // impactful in the location-sensitive case. It seems that it does, however, as without it a
-        // handful of tests fail. That likely means some liveness or outlives data related to choice
-        // regions is missing
-        // FIXME: investigate the impact of loans traversing applied member constraints and why some
-        // tests fail otherwise.
-        //
-        // We first handle the cases where the loan doesn't go out of scope, depending on the
-        // issuing region's successors.
-        for successor in graph::depth_first_search(&self.regioncx.region_graph(), issuing_region) {
-            // Via applied member constraints
-            //
-            // The issuing region can flow into the choice regions, and they are either:
-            // - placeholders or free regions themselves,
-            // - or also transitively outlive a free region.
-            //
-            // That is to say, if there are applied member constraints here, the loan escapes the
-            // function and cannot go out of scope. We could early return here.
-            //
-            // For additional insurance via fuzzing and crater, we verify that the constraint's min
-            // choice indeed escapes the function. In the future, we could e.g. turn this check into
-            // a debug assert and early return as an optimization.
-            let scc = sccs.scc(successor);
-            for constraint in self.regioncx.applied_member_constraints(scc) {
-                if universal_regions.is_universal_region(constraint.min_choice) {
-                    return;
-                }
-            }
-        }
-
+    fn precompute_loans_out_of_scope(&mut self, loan_idx: BorrowIndex, loan_issued_at: Location) {
         let first_block = loan_issued_at.block;
         let first_bb_data = &self.body.basic_blocks[first_block];
 
diff --git a/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs b/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
index fdca6b56540..fda96dde826 100644
--- a/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
@@ -565,7 +565,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, 'tcx> {
         let (blame_constraint, path) = self.regioncx.best_blame_constraint(
             borrow_region,
             NllRegionVariableOrigin::FreeRegion,
-            |r| self.regioncx.provides_universal_region(r, borrow_region, outlived_region),
+            outlived_region,
         );
         let BlameConstraint { category, from_closure, cause, .. } = blame_constraint;
 
diff --git a/compiler/rustc_borrowck/src/diagnostics/mod.rs b/compiler/rustc_borrowck/src/diagnostics/mod.rs
index b67dba3af96..5642cdf87fd 100644
--- a/compiler/rustc_borrowck/src/diagnostics/mod.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/mod.rs
@@ -6,7 +6,9 @@ use rustc_abi::{FieldIdx, VariantIdx};
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_errors::{Applicability, Diag, EmissionGuarantee, MultiSpan, listify};
 use rustc_hir::def::{CtorKind, Namespace};
-use rustc_hir::{self as hir, CoroutineKind, LangItem};
+use rustc_hir::{
+    self as hir, CoroutineKind, GenericBound, LangItem, WhereBoundPredicate, WherePredicateKind,
+};
 use rustc_index::{IndexSlice, IndexVec};
 use rustc_infer::infer::{BoundRegionConversionTime, NllRegionVariableOrigin};
 use rustc_infer::traits::SelectionError;
@@ -658,25 +660,66 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
 
     /// Add a note to region errors and borrow explanations when higher-ranked regions in predicates
     /// implicitly introduce an "outlives `'static`" constraint.
+    ///
+    /// This is very similar to `fn suggest_static_lifetime_for_gat_from_hrtb` which handles this
+    /// note for failed type tests instead of outlives errors.
     fn add_placeholder_from_predicate_note<G: EmissionGuarantee>(
         &self,
-        err: &mut Diag<'_, G>,
+        diag: &mut Diag<'_, G>,
         path: &[OutlivesConstraint<'tcx>],
     ) {
-        let predicate_span = path.iter().find_map(|constraint| {
+        let tcx = self.infcx.tcx;
+        let Some((gat_hir_id, generics)) = path.iter().find_map(|constraint| {
             let outlived = constraint.sub;
             if let Some(origin) = self.regioncx.definitions.get(outlived)
-                && let NllRegionVariableOrigin::Placeholder(_) = origin.origin
-                && let ConstraintCategory::Predicate(span) = constraint.category
+                && let NllRegionVariableOrigin::Placeholder(placeholder) = origin.origin
+                && let Some(id) = placeholder.bound.kind.get_id()
+                && let Some(placeholder_id) = id.as_local()
+                && let gat_hir_id = tcx.local_def_id_to_hir_id(placeholder_id)
+                && let Some(generics_impl) =
+                    tcx.parent_hir_node(tcx.parent_hir_id(gat_hir_id)).generics()
             {
-                Some(span)
+                Some((gat_hir_id, generics_impl))
             } else {
                 None
             }
-        });
+        }) else {
+            return;
+        };
 
-        if let Some(span) = predicate_span {
-            err.span_note(span, "due to current limitations in the borrow checker, this implies a `'static` lifetime");
+        // Look for the where-bound which introduces the placeholder.
+        // As we're using the HIR, we need to handle both `for<'a> T: Trait<'a>`
+        // and `T: for<'a> Trait`<'a>.
+        for pred in generics.predicates {
+            let WherePredicateKind::BoundPredicate(WhereBoundPredicate {
+                bound_generic_params,
+                bounds,
+                ..
+            }) = pred.kind
+            else {
+                continue;
+            };
+            if bound_generic_params
+                .iter()
+                .rfind(|bgp| tcx.local_def_id_to_hir_id(bgp.def_id) == gat_hir_id)
+                .is_some()
+            {
+                diag.span_note(pred.span, fluent::borrowck_limitations_implies_static);
+                return;
+            }
+            for bound in bounds.iter() {
+                if let GenericBound::Trait(bound) = bound {
+                    if bound
+                        .bound_generic_params
+                        .iter()
+                        .rfind(|bgp| tcx.local_def_id_to_hir_id(bgp.def_id) == gat_hir_id)
+                        .is_some()
+                    {
+                        diag.span_note(bound.span, fluent::borrowck_limitations_implies_static);
+                        return;
+                    }
+                }
+            }
         }
     }
 
diff --git a/compiler/rustc_borrowck/src/diagnostics/move_errors.rs b/compiler/rustc_borrowck/src/diagnostics/move_errors.rs
index af71db69483..0b3151fd8b8 100644
--- a/compiler/rustc_borrowck/src/diagnostics/move_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/move_errors.rs
@@ -518,7 +518,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                     .with_span_help(
                         self.get_closure_bound_clause_span(*def_id),
                         "`Fn` and `FnMut` closures require captured values to be able to be \
-                         consumed multiple times, but an `FnOnce` consume them only once",
+                         consumed multiple times, but `FnOnce` closures may consume them only once",
                     )
             }
             _ => {
diff --git a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
index 5d9416b59fc..ea264c8064a 100644
--- a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
@@ -3,6 +3,7 @@
 
 use core::ops::ControlFlow;
 
+use either::Either;
 use hir::{ExprKind, Param};
 use rustc_abi::FieldIdx;
 use rustc_errors::{Applicability, Diag};
@@ -12,15 +13,16 @@ use rustc_middle::bug;
 use rustc_middle::hir::place::PlaceBase;
 use rustc_middle::mir::visit::PlaceContext;
 use rustc_middle::mir::{
-    self, BindingForm, Local, LocalDecl, LocalInfo, LocalKind, Location, Mutability, Place,
-    PlaceRef, ProjectionElem,
+    self, BindingForm, Body, BorrowKind, Local, LocalDecl, LocalInfo, LocalKind, Location,
+    Mutability, Operand, Place, PlaceRef, ProjectionElem, RawPtrKind, Rvalue, Statement,
+    StatementKind, TerminatorKind,
 };
 use rustc_middle::ty::{self, InstanceKind, Ty, TyCtxt, Upcast};
 use rustc_span::{BytePos, DesugaringKind, Span, Symbol, kw, sym};
 use rustc_trait_selection::error_reporting::InferCtxtErrorExt;
 use rustc_trait_selection::infer::InferCtxtExt;
 use rustc_trait_selection::traits;
-use tracing::debug;
+use tracing::{debug, trace};
 
 use crate::diagnostics::BorrowedContentSource;
 use crate::{MirBorrowckCtxt, session_diagnostics};
@@ -31,6 +33,33 @@ pub(crate) enum AccessKind {
     Mutate,
 }
 
+/// Finds all statements that assign directly to local (i.e., X = ...) and returns their
+/// locations.
+fn find_assignments(body: &Body<'_>, local: Local) -> Vec<Location> {
+    use rustc_middle::mir::visit::Visitor;
+
+    struct FindLocalAssignmentVisitor {
+        needle: Local,
+        locations: Vec<Location>,
+    }
+
+    impl<'tcx> Visitor<'tcx> for FindLocalAssignmentVisitor {
+        fn visit_local(&mut self, local: Local, place_context: PlaceContext, location: Location) {
+            if self.needle != local {
+                return;
+            }
+
+            if place_context.is_place_assignment() {
+                self.locations.push(location);
+            }
+        }
+    }
+
+    let mut visitor = FindLocalAssignmentVisitor { needle: local, locations: vec![] };
+    visitor.visit_body(body);
+    visitor.locations
+}
+
 impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
     pub(crate) fn report_mutability_error(
         &mut self,
@@ -384,7 +413,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 }
             }
 
-            // Also suggest adding mut for upvars
+            // Also suggest adding mut for upvars.
             PlaceRef {
                 local,
                 projection: [proj_base @ .., ProjectionElem::Field(upvar_index, _)],
@@ -438,9 +467,8 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 }
             }
 
-            // complete hack to approximate old AST-borrowck
-            // diagnostic: if the span starts with a mutable borrow of
-            // a local variable, then just suggest the user remove it.
+            // Complete hack to approximate old AST-borrowck diagnostic: if the span starts
+            // with a mutable borrow of a local variable, then just suggest the user remove it.
             PlaceRef { local: _, projection: [] }
                 if self
                     .infcx
@@ -677,12 +705,13 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
     ///  - is the trait from the local crate? If not, we can't suggest changing signatures
     ///  - `Span` of the argument in the trait definition
     fn is_error_in_trait(&self, local: Local) -> (bool, bool, Option<Span>) {
+        let tcx = self.infcx.tcx;
         if self.body.local_kind(local) != LocalKind::Arg {
             return (false, false, None);
         }
         let my_def = self.body.source.def_id();
         let Some(td) =
-            self.infcx.tcx.impl_of_assoc(my_def).and_then(|x| self.infcx.tcx.trait_id_of_impl(x))
+            tcx.trait_impl_of_assoc(my_def).and_then(|id| self.infcx.tcx.trait_id_of_impl(id))
         else {
             return (false, false, None);
         };
@@ -768,7 +797,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         );
     }
 
-    // point to span of upvar making closure call require mutable borrow
+    // Point to span of upvar making closure call that requires a mutable borrow
     fn show_mutating_upvar(
         &self,
         tcx: TyCtxt<'_>,
@@ -824,7 +853,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
             } else {
                 bug!("not an upvar")
             };
-            // sometimes we deliberately don't store the name of a place when coming from a macro in
+            // Sometimes we deliberately don't store the name of a place when coming from a macro in
             // another crate. We generally want to limit those diagnostics a little, to hide
             // implementation details (such as those from pin!() or format!()). In that case show a
             // slightly different error message, or none at all if something else happened. In other
@@ -935,8 +964,8 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         let def_id = tcx.hir_enclosing_body_owner(fn_call_id);
         let mut look_at_return = true;
 
-        // If the HIR node is a function or method call gets the def ID
-        // of the called function or method and the span and args of the call expr
+        // If the HIR node is a function or method call, get the DefId
+        // of the callee function or method, the span, and args of the call expr
         let get_call_details = || {
             let hir::Node::Expr(hir::Expr { hir_id, kind, .. }) = node else {
                 return None;
@@ -1050,7 +1079,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
             let mut cur_expr = expr;
             while let ExprKind::MethodCall(path_segment, recv, _, _) = cur_expr.kind {
                 if path_segment.ident.name == sym::iter {
-                    // check `_ty` has `iter_mut` method
+                    // Check that the type has an `iter_mut` method.
                     let res = self
                         .infcx
                         .tcx
@@ -1080,38 +1109,6 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         }
     }
 
-    /// Finds all statements that assign directly to local (i.e., X = ...) and returns their
-    /// locations.
-    fn find_assignments(&self, local: Local) -> Vec<Location> {
-        use rustc_middle::mir::visit::Visitor;
-
-        struct FindLocalAssignmentVisitor {
-            needle: Local,
-            locations: Vec<Location>,
-        }
-
-        impl<'tcx> Visitor<'tcx> for FindLocalAssignmentVisitor {
-            fn visit_local(
-                &mut self,
-                local: Local,
-                place_context: PlaceContext,
-                location: Location,
-            ) {
-                if self.needle != local {
-                    return;
-                }
-
-                if place_context.is_place_assignment() {
-                    self.locations.push(location);
-                }
-            }
-        }
-
-        let mut visitor = FindLocalAssignmentVisitor { needle: local, locations: vec![] };
-        visitor.visit_body(self.body);
-        visitor.locations
-    }
-
     fn suggest_make_local_mut(&self, err: &mut Diag<'_>, local: Local, name: Symbol) {
         let local_decl = &self.body.local_decls[local];
 
@@ -1121,7 +1118,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         let (is_trait_sig, is_local, local_trait) = self.is_error_in_trait(local);
 
         if is_trait_sig && !is_local {
-            // Do not suggest to change the signature when the trait comes from another crate.
+            // Do not suggest changing the signature when the trait comes from another crate.
             err.span_label(
                 local_decl.source_info.span,
                 format!("this is an immutable {pointer_desc}"),
@@ -1130,11 +1127,11 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         }
         let decl_span = local_decl.source_info.span;
 
-        let amp_mut_sugg = match *local_decl.local_info() {
+        let (amp_mut_sugg, local_var_ty_info) = match *local_decl.local_info() {
             LocalInfo::User(mir::BindingForm::ImplicitSelf(_)) => {
                 let (span, suggestion) = suggest_ampmut_self(self.infcx.tcx, decl_span);
                 let additional = local_trait.map(|span| suggest_ampmut_self(self.infcx.tcx, span));
-                Some(AmpMutSugg { has_sugg: true, span, suggestion, additional })
+                (AmpMutSugg::Type { span, suggestion, additional }, None)
             }
 
             LocalInfo::User(mir::BindingForm::Var(mir::VarBindingForm {
@@ -1142,79 +1139,54 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 opt_ty_info,
                 ..
             })) => {
-                // check if the RHS is from desugaring
+                // Check if the RHS is from desugaring.
+                let first_assignment = find_assignments(&self.body, local).first().copied();
+                let first_assignment_stmt = first_assignment
+                    .and_then(|loc| self.body[loc.block].statements.get(loc.statement_index));
+                trace!(?first_assignment_stmt);
                 let opt_assignment_rhs_span =
-                    self.find_assignments(local).first().map(|&location| {
-                        if let Some(mir::Statement {
-                            source_info: _,
-                            kind:
-                                mir::StatementKind::Assign(box (
-                                    _,
-                                    mir::Rvalue::Use(mir::Operand::Copy(place)),
-                                )),
-                            ..
-                        }) = self.body[location.block].statements.get(location.statement_index)
-                        {
-                            self.body.local_decls[place.local].source_info.span
-                        } else {
-                            self.body.source_info(location).span
-                        }
-                    });
-                match opt_assignment_rhs_span.and_then(|s| s.desugaring_kind()) {
-                    // on for loops, RHS points to the iterator part
-                    Some(DesugaringKind::ForLoop) => {
-                        let span = opt_assignment_rhs_span.unwrap();
-                        self.suggest_similar_mut_method_for_for_loop(err, span);
+                    first_assignment.map(|loc| self.body.source_info(loc).span);
+                let mut source_span = opt_assignment_rhs_span;
+                if let Some(mir::Statement {
+                    source_info: _,
+                    kind:
+                        mir::StatementKind::Assign(box (_, mir::Rvalue::Use(mir::Operand::Copy(place)))),
+                    ..
+                }) = first_assignment_stmt
+                {
+                    let local_span = self.body.local_decls[place.local].source_info.span;
+                    // `&self` in async functions have a `desugaring_kind`, but the local we assign
+                    // it with does not, so use the local_span for our checks later.
+                    source_span = Some(local_span);
+                    if let Some(DesugaringKind::ForLoop) = local_span.desugaring_kind() {
+                        // On for loops, RHS points to the iterator part.
+                        self.suggest_similar_mut_method_for_for_loop(err, local_span);
                         err.span_label(
-                            span,
+                            local_span,
                             format!("this iterator yields `{pointer_sigil}` {pointer_desc}s",),
                         );
-                        None
-                    }
-                    // don't create labels for compiler-generated spans
-                    Some(_) => None,
-                    // don't create labels for the span not from user's code
-                    None if opt_assignment_rhs_span
-                        .is_some_and(|span| self.infcx.tcx.sess.source_map().is_imported(span)) =>
-                    {
-                        None
-                    }
-                    None => {
-                        if name != kw::SelfLower {
-                            suggest_ampmut(
-                                self.infcx.tcx,
-                                local_decl.ty,
-                                decl_span,
-                                opt_assignment_rhs_span,
-                                opt_ty_info,
-                            )
-                        } else {
-                            match local_decl.local_info() {
-                                LocalInfo::User(mir::BindingForm::Var(mir::VarBindingForm {
-                                    opt_ty_info: None,
-                                    ..
-                                })) => {
-                                    let (span, sugg) =
-                                        suggest_ampmut_self(self.infcx.tcx, decl_span);
-                                    Some(AmpMutSugg {
-                                        has_sugg: true,
-                                        span,
-                                        suggestion: sugg,
-                                        additional: None,
-                                    })
-                                }
-                                // explicit self (eg `self: &'a Self`)
-                                _ => suggest_ampmut(
-                                    self.infcx.tcx,
-                                    local_decl.ty,
-                                    decl_span,
-                                    opt_assignment_rhs_span,
-                                    opt_ty_info,
-                                ),
-                            }
-                        }
+                        return;
                     }
                 }
+
+                // Don't create labels for compiler-generated spans or spans not from users' code.
+                if source_span.is_some_and(|s| {
+                    s.desugaring_kind().is_some() || self.infcx.tcx.sess.source_map().is_imported(s)
+                }) {
+                    return;
+                }
+
+                // This could be because we're in an `async fn`.
+                if name == kw::SelfLower && opt_ty_info.is_none() {
+                    let (span, suggestion) = suggest_ampmut_self(self.infcx.tcx, decl_span);
+                    (AmpMutSugg::Type { span, suggestion, additional: None }, None)
+                } else if let Some(sugg) =
+                    suggest_ampmut(self.infcx, self.body(), first_assignment_stmt)
+                {
+                    (sugg, opt_ty_info)
+                } else {
+                    return;
+                }
             }
 
             LocalInfo::User(mir::BindingForm::Var(mir::VarBindingForm {
@@ -1222,181 +1194,238 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 ..
             })) => {
                 let pattern_span: Span = local_decl.source_info.span;
-                suggest_ref_mut(self.infcx.tcx, pattern_span).map(|span| AmpMutSugg {
-                    has_sugg: true,
-                    span,
-                    suggestion: "mut ".to_owned(),
-                    additional: None,
-                })
+                let Some(span) = suggest_ref_mut(self.infcx.tcx, pattern_span) else {
+                    return;
+                };
+                (AmpMutSugg::Type { span, suggestion: "mut ".to_owned(), additional: None }, None)
             }
 
             _ => unreachable!(),
         };
 
-        match amp_mut_sugg {
-            Some(AmpMutSugg {
-                has_sugg: true,
-                span: err_help_span,
-                suggestion: suggested_code,
-                additional,
-            }) => {
-                let mut sugg = vec![(err_help_span, suggested_code)];
-                if let Some(s) = additional {
-                    sugg.push(s);
-                }
+        let mut suggest = |suggs: Vec<_>, applicability, extra| {
+            if suggs.iter().any(|(span, _)| self.infcx.tcx.sess.source_map().is_imported(*span)) {
+                return;
+            }
 
-                if sugg.iter().all(|(span, _)| !self.infcx.tcx.sess.source_map().is_imported(*span))
-                {
-                    err.multipart_suggestion_verbose(
-                        format!(
-                            "consider changing this to be a mutable {pointer_desc}{}",
-                            if is_trait_sig {
-                                " in the `impl` method and the `trait` definition"
-                            } else {
-                                ""
-                            }
-                        ),
-                        sugg,
-                        Applicability::MachineApplicable,
-                    );
+            err.multipart_suggestion_verbose(
+                format!(
+                    "consider changing this to be a mutable {pointer_desc}{}{extra}",
+                    if is_trait_sig {
+                        " in the `impl` method and the `trait` definition"
+                    } else {
+                        ""
+                    }
+                ),
+                suggs,
+                applicability,
+            );
+        };
+
+        let (mut sugg, add_type_annotation_if_not_exists) = match amp_mut_sugg {
+            AmpMutSugg::Type { span, suggestion, additional } => {
+                let mut sugg = vec![(span, suggestion)];
+                sugg.extend(additional);
+                suggest(sugg, Applicability::MachineApplicable, "");
+                return;
+            }
+            AmpMutSugg::MapGetMut { span, suggestion } => {
+                if self.infcx.tcx.sess.source_map().is_imported(span) {
+                    return;
                 }
+                err.multipart_suggestion_verbose(
+                    "consider using `get_mut`",
+                    vec![(span, suggestion)],
+                    Applicability::MaybeIncorrect,
+                );
+                return;
             }
-            Some(AmpMutSugg {
-                has_sugg: false, span: err_label_span, suggestion: message, ..
-            }) => {
-                let def_id = self.body.source.def_id();
-                let hir_id = if let Some(local_def_id) = def_id.as_local()
-                    && let Some(body) = self.infcx.tcx.hir_maybe_body_owned_by(local_def_id)
-                {
-                    BindingFinder { span: err_label_span }.visit_body(&body).break_value()
-                } else {
-                    None
-                };
+            AmpMutSugg::Expr { span, suggestion } => {
+                // `Expr` suggestions should change type annotations if they already exist (probably immut),
+                // but do not add new type annotations.
+                (vec![(span, suggestion)], false)
+            }
+            AmpMutSugg::ChangeBinding => (vec![], true),
+        };
 
-                if let Some(hir_id) = hir_id
-                    && let hir::Node::LetStmt(local) = self.infcx.tcx.hir_node(hir_id)
-                {
-                    let tables = self.infcx.tcx.typeck(def_id.as_local().unwrap());
-                    if let Some(clone_trait) = self.infcx.tcx.lang_items().clone_trait()
-                        && let Some(expr) = local.init
-                        && let ty = tables.node_type_opt(expr.hir_id)
-                        && let Some(ty) = ty
-                        && let ty::Ref(..) = ty.kind()
+        // Find a binding's type to make mutable.
+        let (binding_exists, span) = match local_var_ty_info {
+            // If this is a variable binding with an explicit type,
+            // then we will suggest changing it to be mutable.
+            // This is `Applicability::MachineApplicable`.
+            Some(ty_span) => (true, ty_span),
+
+            // Otherwise, we'll suggest *adding* an annotated type, we'll suggest
+            // the RHS's type for that.
+            // This is `Applicability::HasPlaceholders`.
+            None => (false, decl_span),
+        };
+
+        if !binding_exists && !add_type_annotation_if_not_exists {
+            suggest(sugg, Applicability::MachineApplicable, "");
+            return;
+        }
+
+        // If the binding already exists and is a reference with an explicit
+        // lifetime, then we can suggest adding ` mut`. This is special-cased from
+        // the path without an explicit lifetime.
+        let (sugg_span, sugg_str, suggest_now) = if let Ok(src) = self.infcx.tcx.sess.source_map().span_to_snippet(span)
+            && src.starts_with("&'")
+            // Note that `&' a T` is invalid so this is correct.
+            && let Some(ws_pos) = src.find(char::is_whitespace)
+        {
+            let span = span.with_lo(span.lo() + BytePos(ws_pos as u32)).shrink_to_lo();
+            (span, " mut".to_owned(), true)
+        // If there is already a binding, we modify it to be `mut`.
+        } else if binding_exists {
+            // Shrink the span to just after the `&` in `&variable`.
+            let span = span.with_lo(span.lo() + BytePos(1)).shrink_to_lo();
+            (span, "mut ".to_owned(), true)
+        } else {
+            // Otherwise, suggest that the user annotates the binding; We provide the
+            // type of the local.
+            let ty = local_decl.ty.builtin_deref(true).unwrap();
+
+            (span, format!("{}mut {}", if local_decl.ty.is_ref() { "&" } else { "*" }, ty), false)
+        };
+
+        if suggest_now {
+            // Suggest changing `&x` to `&mut x` and changing `&T` to `&mut T` at the same time.
+            let has_change = !sugg.is_empty();
+            sugg.push((sugg_span, sugg_str));
+            suggest(
+                sugg,
+                Applicability::MachineApplicable,
+                // FIXME(fee1-dead) this somehow doesn't fire
+                if has_change { " and changing the binding's type" } else { "" },
+            );
+            return;
+        } else if !sugg.is_empty() {
+            suggest(sugg, Applicability::MachineApplicable, "");
+            return;
+        }
+
+        let def_id = self.body.source.def_id();
+        let hir_id = if let Some(local_def_id) = def_id.as_local()
+            && let Some(body) = self.infcx.tcx.hir_maybe_body_owned_by(local_def_id)
+        {
+            BindingFinder { span: sugg_span }.visit_body(&body).break_value()
+        } else {
+            None
+        };
+        let node = hir_id.map(|hir_id| self.infcx.tcx.hir_node(hir_id));
+
+        let Some(hir::Node::LetStmt(local)) = node else {
+            err.span_label(
+                sugg_span,
+                format!("consider changing this binding's type to be: `{sugg_str}`"),
+            );
+            return;
+        };
+
+        let tables = self.infcx.tcx.typeck(def_id.as_local().unwrap());
+        if let Some(clone_trait) = self.infcx.tcx.lang_items().clone_trait()
+            && let Some(expr) = local.init
+            && let ty = tables.node_type_opt(expr.hir_id)
+            && let Some(ty) = ty
+            && let ty::Ref(..) = ty.kind()
+        {
+            match self
+                .infcx
+                .type_implements_trait_shallow(clone_trait, ty.peel_refs(), self.infcx.param_env)
+                .as_deref()
+            {
+                Some([]) => {
+                    // FIXME: This error message isn't useful, since we're just
+                    // vaguely suggesting to clone a value that already
+                    // implements `Clone`.
+                    //
+                    // A correct suggestion here would take into account the fact
+                    // that inference may be affected by missing types on bindings,
+                    // etc., to improve "tests/ui/borrowck/issue-91206.stderr", for
+                    // example.
+                }
+                None => {
+                    if let hir::ExprKind::MethodCall(segment, _rcvr, [], span) = expr.kind
+                        && segment.ident.name == sym::clone
                     {
-                        match self
-                            .infcx
-                            .type_implements_trait_shallow(
-                                clone_trait,
-                                ty.peel_refs(),
-                                self.infcx.param_env,
-                            )
-                            .as_deref()
-                        {
-                            Some([]) => {
-                                // FIXME: This error message isn't useful, since we're just
-                                // vaguely suggesting to clone a value that already
-                                // implements `Clone`.
-                                //
-                                // A correct suggestion here would take into account the fact
-                                // that inference may be affected by missing types on bindings,
-                                // etc., to improve "tests/ui/borrowck/issue-91206.stderr", for
-                                // example.
-                            }
-                            None => {
-                                if let hir::ExprKind::MethodCall(segment, _rcvr, [], span) =
-                                    expr.kind
-                                    && segment.ident.name == sym::clone
-                                {
-                                    err.span_help(
-                                        span,
-                                        format!(
-                                            "`{}` doesn't implement `Clone`, so this call clones \
+                        err.span_help(
+                            span,
+                            format!(
+                                "`{}` doesn't implement `Clone`, so this call clones \
                                              the reference `{ty}`",
-                                            ty.peel_refs(),
-                                        ),
-                                    );
-                                }
-                                // The type doesn't implement Clone.
-                                let trait_ref = ty::Binder::dummy(ty::TraitRef::new(
-                                    self.infcx.tcx,
-                                    clone_trait,
-                                    [ty.peel_refs()],
-                                ));
-                                let obligation = traits::Obligation::new(
-                                    self.infcx.tcx,
-                                    traits::ObligationCause::dummy(),
-                                    self.infcx.param_env,
-                                    trait_ref,
-                                );
-                                self.infcx.err_ctxt().suggest_derive(
-                                    &obligation,
-                                    err,
-                                    trait_ref.upcast(self.infcx.tcx),
-                                );
-                            }
-                            Some(errors) => {
-                                if let hir::ExprKind::MethodCall(segment, _rcvr, [], span) =
-                                    expr.kind
-                                    && segment.ident.name == sym::clone
-                                {
-                                    err.span_help(
-                                        span,
-                                        format!(
-                                            "`{}` doesn't implement `Clone` because its \
+                                ty.peel_refs(),
+                            ),
+                        );
+                    }
+                    // The type doesn't implement Clone.
+                    let trait_ref = ty::Binder::dummy(ty::TraitRef::new(
+                        self.infcx.tcx,
+                        clone_trait,
+                        [ty.peel_refs()],
+                    ));
+                    let obligation = traits::Obligation::new(
+                        self.infcx.tcx,
+                        traits::ObligationCause::dummy(),
+                        self.infcx.param_env,
+                        trait_ref,
+                    );
+                    self.infcx.err_ctxt().suggest_derive(
+                        &obligation,
+                        err,
+                        trait_ref.upcast(self.infcx.tcx),
+                    );
+                }
+                Some(errors) => {
+                    if let hir::ExprKind::MethodCall(segment, _rcvr, [], span) = expr.kind
+                        && segment.ident.name == sym::clone
+                    {
+                        err.span_help(
+                            span,
+                            format!(
+                                "`{}` doesn't implement `Clone` because its \
                                              implementations trait bounds could not be met, so \
                                              this call clones the reference `{ty}`",
-                                            ty.peel_refs(),
-                                        ),
-                                    );
-                                    err.note(format!(
-                                        "the following trait bounds weren't met: {}",
-                                        errors
-                                            .iter()
-                                            .map(|e| e.obligation.predicate.to_string())
-                                            .collect::<Vec<_>>()
-                                            .join("\n"),
-                                    ));
-                                }
-                                // The type doesn't implement Clone because of unmet obligations.
-                                for error in errors {
-                                    if let traits::FulfillmentErrorCode::Select(
-                                        traits::SelectionError::Unimplemented,
-                                    ) = error.code
-                                        && let ty::PredicateKind::Clause(ty::ClauseKind::Trait(
-                                            pred,
-                                        )) = error.obligation.predicate.kind().skip_binder()
-                                    {
-                                        self.infcx.err_ctxt().suggest_derive(
-                                            &error.obligation,
-                                            err,
-                                            error.obligation.predicate.kind().rebind(pred),
-                                        );
-                                    }
-                                }
-                            }
-                        }
+                                ty.peel_refs(),
+                            ),
+                        );
+                        err.note(format!(
+                            "the following trait bounds weren't met: {}",
+                            errors
+                                .iter()
+                                .map(|e| e.obligation.predicate.to_string())
+                                .collect::<Vec<_>>()
+                                .join("\n"),
+                        ));
                     }
-                    let (changing, span, sugg) = match local.ty {
-                        Some(ty) => ("changing", ty.span, message),
-                        None => {
-                            ("specifying", local.pat.span.shrink_to_hi(), format!(": {message}"))
+                    // The type doesn't implement Clone because of unmet obligations.
+                    for error in errors {
+                        if let traits::FulfillmentErrorCode::Select(
+                            traits::SelectionError::Unimplemented,
+                        ) = error.code
+                            && let ty::PredicateKind::Clause(ty::ClauseKind::Trait(pred)) =
+                                error.obligation.predicate.kind().skip_binder()
+                        {
+                            self.infcx.err_ctxt().suggest_derive(
+                                &error.obligation,
+                                err,
+                                error.obligation.predicate.kind().rebind(pred),
+                            );
                         }
-                    };
-                    err.span_suggestion_verbose(
-                        span,
-                        format!("consider {changing} this binding's type"),
-                        sugg,
-                        Applicability::HasPlaceholders,
-                    );
-                } else {
-                    err.span_label(
-                        err_label_span,
-                        format!("consider changing this binding's type to be: `{message}`"),
-                    );
+                    }
                 }
             }
-            None => {}
         }
+        let (changing, span, sugg) = match local.ty {
+            Some(ty) => ("changing", ty.span, sugg_str),
+            None => ("specifying", local.pat.span.shrink_to_hi(), format!(": {sugg_str}")),
+        };
+        err.span_suggestion_verbose(
+            span,
+            format!("consider {changing} this binding's type"),
+            sugg,
+            Applicability::HasPlaceholders,
+        );
     }
 }
 
@@ -1463,11 +1492,25 @@ fn suggest_ampmut_self(tcx: TyCtxt<'_>, span: Span) -> (Span, String) {
     }
 }
 
-struct AmpMutSugg {
-    has_sugg: bool,
-    span: Span,
-    suggestion: String,
-    additional: Option<(Span, String)>,
+enum AmpMutSugg {
+    /// Type suggestion. Changes `&self` to `&mut self`, `x: &T` to `x: &mut T`,
+    /// `ref x` to `ref mut x`, etc.
+    Type {
+        span: Span,
+        suggestion: String,
+        additional: Option<(Span, String)>,
+    },
+    /// Suggestion for expressions, `&x` to `&mut x`, `&x[i]` to `&mut x[i]`, etc.
+    Expr {
+        span: Span,
+        suggestion: String,
+    },
+    /// Suggests `.get_mut` in the case of `&map[&key]` for Hash/BTreeMap.
+    MapGetMut {
+        span: Span,
+        suggestion: String,
+    },
+    ChangeBinding,
 }
 
 // When we want to suggest a user change a local variable to be a `&mut`, there
@@ -1486,110 +1529,111 @@ struct AmpMutSugg {
 // This implementation attempts to emulate AST-borrowck prioritization
 // by trying (3.), then (2.) and finally falling back on (1.).
 fn suggest_ampmut<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    decl_ty: Ty<'tcx>,
-    decl_span: Span,
-    opt_assignment_rhs_span: Option<Span>,
-    opt_ty_info: Option<Span>,
+    infcx: &crate::BorrowckInferCtxt<'tcx>,
+    body: &Body<'tcx>,
+    opt_assignment_rhs_stmt: Option<&Statement<'tcx>>,
 ) -> Option<AmpMutSugg> {
-    // if there is a RHS and it starts with a `&` from it, then check if it is
+    let tcx = infcx.tcx;
+    // If there is a RHS and it starts with a `&` from it, then check if it is
     // mutable, and if not, put suggest putting `mut ` to make it mutable.
-    // we don't have to worry about lifetime annotations here because they are
+    // We don't have to worry about lifetime annotations here because they are
     // not valid when taking a reference. For example, the following is not valid Rust:
     //
     // let x: &i32 = &'a 5;
     //                ^^ lifetime annotation not allowed
     //
-    if let Some(rhs_span) = opt_assignment_rhs_span
-        && let Ok(rhs_str) = tcx.sess.source_map().span_to_snippet(rhs_span)
-        && let Some(rhs_str_no_amp) = rhs_str.strip_prefix('&')
+    if let Some(rhs_stmt) = opt_assignment_rhs_stmt
+        && let StatementKind::Assign(box (lhs, rvalue)) = &rhs_stmt.kind
+        && let mut rhs_span = rhs_stmt.source_info.span
+        && let Ok(mut rhs_str) = tcx.sess.source_map().span_to_snippet(rhs_span)
     {
-        // Suggest changing `&raw const` to `&raw mut` if applicable.
-        if rhs_str_no_amp.trim_start().strip_prefix("raw const").is_some() {
-            let const_idx = rhs_str.find("const").unwrap() as u32;
-            let const_span = rhs_span
-                .with_lo(rhs_span.lo() + BytePos(const_idx))
-                .with_hi(rhs_span.lo() + BytePos(const_idx + "const".len() as u32));
-
-            return Some(AmpMutSugg {
-                has_sugg: true,
-                span: const_span,
-                suggestion: "mut".to_owned(),
-                additional: None,
-            });
+        let mut rvalue = rvalue;
+
+        // Take some special care when handling `let _x = &*_y`:
+        // We want to know if this is part of an overloaded index, so `let x = &a[0]`,
+        // or whether this is a usertype ascription (`let _x: &T = y`).
+        if let Rvalue::Ref(_, BorrowKind::Shared, place) = rvalue
+            && place.projection.len() == 1
+            && place.projection[0] == ProjectionElem::Deref
+            && let Some(assign) = find_assignments(&body, place.local).first()
+        {
+            // If this is a usertype ascription (`let _x: &T = _y`) then pierce through it as either we want
+            // to suggest `&mut` on the expression (handled here) or we return `None` and let the caller
+            // suggest `&mut` on the type if the expression seems fine (e.g. `let _x: &T = &mut _y`).
+            if let Some(user_ty_projs) = body.local_decls[lhs.local].user_ty.as_ref()
+                && let [user_ty_proj] = user_ty_projs.contents.as_slice()
+                && user_ty_proj.projs.is_empty()
+                && let Either::Left(rhs_stmt_new) = body.stmt_at(*assign)
+                && let StatementKind::Assign(box (_, rvalue_new)) = &rhs_stmt_new.kind
+                && let rhs_span_new = rhs_stmt_new.source_info.span
+                && let Ok(rhs_str_new) = tcx.sess.source_map().span_to_snippet(rhs_span)
+            {
+                (rvalue, rhs_span, rhs_str) = (rvalue_new, rhs_span_new, rhs_str_new);
+            }
+
+            if let Either::Right(call) = body.stmt_at(*assign)
+                && let TerminatorKind::Call {
+                    func: Operand::Constant(box const_operand), args, ..
+                } = &call.kind
+                && let ty::FnDef(method_def_id, method_args) = *const_operand.ty().kind()
+                && let Some(trait_) = tcx.trait_of_assoc(method_def_id)
+                && tcx.is_lang_item(trait_, hir::LangItem::Index)
+            {
+                let trait_ref = ty::TraitRef::from_assoc(
+                    tcx,
+                    tcx.require_lang_item(hir::LangItem::IndexMut, rhs_span),
+                    method_args,
+                );
+                // The type only implements `Index` but not `IndexMut`, we must not suggest `&mut`.
+                if !infcx
+                    .type_implements_trait(trait_ref.def_id, trait_ref.args, infcx.param_env)
+                    .must_apply_considering_regions()
+                {
+                    // Suggest `get_mut` if type is a `BTreeMap` or `HashMap`.
+                    if let ty::Adt(def, _) = trait_ref.self_ty().kind()
+                        && [sym::BTreeMap, sym::HashMap]
+                            .into_iter()
+                            .any(|s| tcx.is_diagnostic_item(s, def.did()))
+                        && let [map, key] = &**args
+                        && let Ok(map) = tcx.sess.source_map().span_to_snippet(map.span)
+                        && let Ok(key) = tcx.sess.source_map().span_to_snippet(key.span)
+                    {
+                        let span = rhs_span;
+                        let suggestion = format!("{map}.get_mut({key}).unwrap()");
+                        return Some(AmpMutSugg::MapGetMut { span, suggestion });
+                    }
+                    return None;
+                }
+            }
         }
 
-        // Figure out if rhs already is `&mut`.
-        let is_mut = if let Some(rest) = rhs_str_no_amp.trim_start().strip_prefix("mut") {
-            match rest.chars().next() {
-                // e.g. `&mut x`
-                Some(c) if c.is_whitespace() => true,
-                // e.g. `&mut(x)`
-                Some('(') => true,
-                // e.g. `&mut{x}`
-                Some('{') => true,
-                // e.g. `&mutablevar`
-                _ => false,
+        let sugg = match rvalue {
+            Rvalue::Ref(_, BorrowKind::Shared, _) if let Some(ref_idx) = rhs_str.find('&') => {
+                // Shrink the span to just after the `&` in `&variable`.
+                Some((
+                    rhs_span.with_lo(rhs_span.lo() + BytePos(ref_idx as u32 + 1)).shrink_to_lo(),
+                    "mut ".to_owned(),
+                ))
             }
-        } else {
-            false
+            Rvalue::RawPtr(RawPtrKind::Const, _) if let Some(const_idx) = rhs_str.find("const") => {
+                // Suggest changing `&raw const` to `&raw mut` if applicable.
+                let const_idx = const_idx as u32;
+                Some((
+                    rhs_span
+                        .with_lo(rhs_span.lo() + BytePos(const_idx))
+                        .with_hi(rhs_span.lo() + BytePos(const_idx + "const".len() as u32)),
+                    "mut".to_owned(),
+                ))
+            }
+            _ => None,
         };
-        // if the reference is already mutable then there is nothing we can do
-        // here.
-        if !is_mut {
-            // shrink the span to just after the `&` in `&variable`
-            let span = rhs_span.with_lo(rhs_span.lo() + BytePos(1)).shrink_to_lo();
-
-            // FIXME(Ezrashaw): returning is bad because we still might want to
-            // update the annotated type, see #106857.
-            return Some(AmpMutSugg {
-                has_sugg: true,
-                span,
-                suggestion: "mut ".to_owned(),
-                additional: None,
-            });
+
+        if let Some((span, suggestion)) = sugg {
+            return Some(AmpMutSugg::Expr { span, suggestion });
         }
     }
 
-    let (binding_exists, span) = match opt_ty_info {
-        // if this is a variable binding with an explicit type,
-        // then we will suggest changing it to be mutable.
-        // this is `Applicability::MachineApplicable`.
-        Some(ty_span) => (true, ty_span),
-
-        // otherwise, we'll suggest *adding* an annotated type, we'll suggest
-        // the RHS's type for that.
-        // this is `Applicability::HasPlaceholders`.
-        None => (false, decl_span),
-    };
-
-    // if the binding already exists and is a reference with an explicit
-    // lifetime, then we can suggest adding ` mut`. this is special-cased from
-    // the path without an explicit lifetime.
-    if let Ok(src) = tcx.sess.source_map().span_to_snippet(span)
-        && src.starts_with("&'")
-        // note that `&     'a T` is invalid so this is correct.
-        && let Some(ws_pos) = src.find(char::is_whitespace)
-    {
-        let span = span.with_lo(span.lo() + BytePos(ws_pos as u32)).shrink_to_lo();
-        Some(AmpMutSugg { has_sugg: true, span, suggestion: " mut".to_owned(), additional: None })
-    // if there is already a binding, we modify it to be `mut`
-    } else if binding_exists {
-        // shrink the span to just after the `&` in `&variable`
-        let span = span.with_lo(span.lo() + BytePos(1)).shrink_to_lo();
-        Some(AmpMutSugg { has_sugg: true, span, suggestion: "mut ".to_owned(), additional: None })
-    } else {
-        // otherwise, suggest that the user annotates the binding; we provide the
-        // type of the local.
-        let ty = decl_ty.builtin_deref(true).unwrap();
-
-        Some(AmpMutSugg {
-            has_sugg: false,
-            span,
-            suggestion: format!("{}mut {}", if decl_ty.is_ref() { "&" } else { "*" }, ty),
-            additional: None,
-        })
-    }
+    Some(AmpMutSugg::ChangeBinding)
 }
 
 /// If the type is a `Coroutine`, `Closure`, or `CoroutineClosure`
diff --git a/compiler/rustc_borrowck/src/diagnostics/opaque_types.rs b/compiler/rustc_borrowck/src/diagnostics/opaque_types.rs
index 83fe4a9f98f..99913626418 100644
--- a/compiler/rustc_borrowck/src/diagnostics/opaque_types.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/opaque_types.rs
@@ -13,6 +13,8 @@ use rustc_middle::mir::{self, ConstraintCategory, Location};
 use rustc_middle::ty::{
     self, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor,
 };
+use rustc_span::Span;
+use rustc_trait_selection::error_reporting::infer::region::unexpected_hidden_region_diagnostic;
 use rustc_trait_selection::errors::impl_trait_overcapture_suggestion;
 
 use crate::MirBorrowckCtxt;
@@ -26,13 +28,61 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         if errors.is_empty() {
             return;
         }
+
+        let infcx = self.infcx;
         let mut guar = None;
+        let mut last_unexpected_hidden_region: Option<(Span, Ty<'_>, ty::OpaqueTypeKey<'tcx>)> =
+            None;
         for error in errors {
             guar = Some(match error {
-                DeferredOpaqueTypeError::InvalidOpaqueTypeArgs(err) => err.report(self.infcx),
+                DeferredOpaqueTypeError::InvalidOpaqueTypeArgs(err) => err.report(infcx),
                 DeferredOpaqueTypeError::LifetimeMismatchOpaqueParam(err) => {
-                    self.infcx.dcx().emit_err(err)
+                    infcx.dcx().emit_err(err)
+                }
+                DeferredOpaqueTypeError::UnexpectedHiddenRegion {
+                    opaque_type_key,
+                    hidden_type,
+                    member_region,
+                } => {
+                    let named_ty =
+                        self.regioncx.name_regions_for_member_constraint(infcx.tcx, hidden_type.ty);
+                    let named_key = self
+                        .regioncx
+                        .name_regions_for_member_constraint(infcx.tcx, opaque_type_key);
+                    let named_region =
+                        self.regioncx.name_regions_for_member_constraint(infcx.tcx, member_region);
+                    let diag = unexpected_hidden_region_diagnostic(
+                        infcx,
+                        self.mir_def_id(),
+                        hidden_type.span,
+                        named_ty,
+                        named_region,
+                        named_key,
+                    );
+                    if last_unexpected_hidden_region
+                        != Some((hidden_type.span, named_ty, named_key))
+                    {
+                        last_unexpected_hidden_region =
+                            Some((hidden_type.span, named_ty, named_key));
+                        diag.emit()
+                    } else {
+                        diag.delay_as_bug()
+                    }
                 }
+                DeferredOpaqueTypeError::NonDefiningUseInDefiningScope {
+                    span,
+                    opaque_type_key,
+                } => infcx.dcx().span_err(
+                    span,
+                    format!(
+                        "non-defining use of `{}` in the defining scope",
+                        Ty::new_opaque(
+                            infcx.tcx,
+                            opaque_type_key.def_id.to_def_id(),
+                            opaque_type_key.args
+                        )
+                    ),
+                ),
             });
         }
         let guar = guar.unwrap();
@@ -193,10 +243,9 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for FindOpaqueRegion<'_, 'tcx> {
                 let opaque_region_vid = self.regioncx.to_region_vid(opaque_region);
 
                 // Find a path between the borrow region and our opaque capture.
-                if let Some((path, _)) =
-                    self.regioncx.find_constraint_paths_between_regions(self.borrow_region, |r| {
-                        r == opaque_region_vid
-                    })
+                if let Some(path) = self
+                    .regioncx
+                    .constraint_path_between_regions(self.borrow_region, opaque_region_vid)
                 {
                     for constraint in path {
                         // If we find a call in this path, then check if it defines the opaque.
diff --git a/compiler/rustc_borrowck/src/diagnostics/region_errors.rs b/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
index 2b74f1a48f7..bec4c934502 100644
--- a/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/region_errors.rs
@@ -23,7 +23,6 @@ use rustc_trait_selection::error_reporting::infer::nice_region_error::{
     self, HirTraitObjectVisitor, NiceRegionError, TraitObjectVisitor, find_anon_type,
     find_param_with_region, suggest_adding_lifetime_params,
 };
-use rustc_trait_selection::error_reporting::infer::region::unexpected_hidden_region_diagnostic;
 use rustc_trait_selection::infer::InferCtxtExt;
 use rustc_trait_selection::traits::{Obligation, ObligationCtxt};
 use tracing::{debug, instrument, trace};
@@ -62,7 +61,7 @@ impl<'tcx> ConstraintDescription for ConstraintCategory<'tcx> {
             | ConstraintCategory::Boring
             | ConstraintCategory::BoringNoLocation
             | ConstraintCategory::Internal
-            | ConstraintCategory::IllegalUniverse => "",
+            | ConstraintCategory::OutlivesUnnameablePlaceholder(..) => "",
         }
     }
 }
@@ -105,18 +104,6 @@ pub(crate) enum RegionErrorKind<'tcx> {
     /// A generic bound failure for a type test (`T: 'a`).
     TypeTestError { type_test: TypeTest<'tcx> },
 
-    /// An unexpected hidden region for an opaque type.
-    UnexpectedHiddenRegion {
-        /// The span for the member constraint.
-        span: Span,
-        /// The hidden type.
-        hidden_ty: Ty<'tcx>,
-        /// The opaque type.
-        key: ty::OpaqueTypeKey<'tcx>,
-        /// The unexpected region.
-        member_region: ty::Region<'tcx>,
-    },
-
     /// Higher-ranked subtyping error.
     BoundUniversalRegionError {
         /// The placeholder free region.
@@ -215,7 +202,6 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         diag: &mut Diag<'_>,
         lower_bound: RegionVid,
     ) {
-        let mut suggestions = vec![];
         let tcx = self.infcx.tcx;
 
         // find generic associated types in the given region 'lower_bound'
@@ -237,9 +223,11 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
             .collect::<Vec<_>>();
         debug!(?gat_id_and_generics);
 
-        // find higher-ranked trait bounds bounded to the generic associated types
+        // Look for the where-bound which introduces the placeholder.
+        // As we're using the HIR, we need to handle both `for<'a> T: Trait<'a>`
+        // and `T: for<'a> Trait`<'a>.
         let mut hrtb_bounds = vec![];
-        gat_id_and_generics.iter().flatten().for_each(|(gat_hir_id, generics)| {
+        gat_id_and_generics.iter().flatten().for_each(|&(gat_hir_id, generics)| {
             for pred in generics.predicates {
                 let BoundPredicate(WhereBoundPredicate { bound_generic_params, bounds, .. }) =
                     pred.kind
@@ -248,17 +236,32 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 };
                 if bound_generic_params
                     .iter()
-                    .rfind(|bgp| tcx.local_def_id_to_hir_id(bgp.def_id) == *gat_hir_id)
+                    .rfind(|bgp| tcx.local_def_id_to_hir_id(bgp.def_id) == gat_hir_id)
                     .is_some()
                 {
                     for bound in *bounds {
                         hrtb_bounds.push(bound);
                     }
+                } else {
+                    for bound in *bounds {
+                        if let Trait(trait_bound) = bound {
+                            if trait_bound
+                                .bound_generic_params
+                                .iter()
+                                .rfind(|bgp| tcx.local_def_id_to_hir_id(bgp.def_id) == gat_hir_id)
+                                .is_some()
+                            {
+                                hrtb_bounds.push(bound);
+                                return;
+                            }
+                        }
+                    }
                 }
             }
         });
         debug!(?hrtb_bounds);
 
+        let mut suggestions = vec![];
         hrtb_bounds.iter().for_each(|bound| {
             let Trait(PolyTraitRef { trait_ref, span: trait_span, .. }) = bound else {
                 return;
@@ -307,11 +310,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
     pub(crate) fn report_region_errors(&mut self, nll_errors: RegionErrors<'tcx>) {
         // Iterate through all the errors, producing a diagnostic for each one. The diagnostics are
         // buffered in the `MirBorrowckCtxt`.
-
         let mut outlives_suggestion = OutlivesSuggestionBuilder::default();
-        let mut last_unexpected_hidden_region: Option<(Span, Ty<'_>, ty::OpaqueTypeKey<'tcx>)> =
-            None;
-
         for (nll_error, _) in nll_errors.into_iter() {
             match nll_error {
                 RegionErrorKind::TypeTestError { type_test } => {
@@ -362,30 +361,6 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                     }
                 }
 
-                RegionErrorKind::UnexpectedHiddenRegion { span, hidden_ty, key, member_region } => {
-                    let named_ty =
-                        self.regioncx.name_regions_for_member_constraint(self.infcx.tcx, hidden_ty);
-                    let named_key =
-                        self.regioncx.name_regions_for_member_constraint(self.infcx.tcx, key);
-                    let named_region = self
-                        .regioncx
-                        .name_regions_for_member_constraint(self.infcx.tcx, member_region);
-                    let diag = unexpected_hidden_region_diagnostic(
-                        self.infcx,
-                        self.mir_def_id(),
-                        span,
-                        named_ty,
-                        named_region,
-                        named_key,
-                    );
-                    if last_unexpected_hidden_region != Some((span, named_ty, named_key)) {
-                        self.buffer_error(diag);
-                        last_unexpected_hidden_region = Some((span, named_ty, named_key));
-                    } else {
-                        diag.delay_as_bug();
-                    }
-                }
-
                 RegionErrorKind::BoundUniversalRegionError {
                     longer_fr,
                     placeholder,
@@ -394,11 +369,15 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                     let error_vid = self.regioncx.region_from_element(longer_fr, &error_element);
 
                     // Find the code to blame for the fact that `longer_fr` outlives `error_fr`.
-                    let (_, cause) = self.regioncx.find_outlives_blame_span(
-                        longer_fr,
-                        NllRegionVariableOrigin::Placeholder(placeholder),
-                        error_vid,
-                    );
+                    let cause = self
+                        .regioncx
+                        .best_blame_constraint(
+                            longer_fr,
+                            NllRegionVariableOrigin::Placeholder(placeholder),
+                            error_vid,
+                        )
+                        .0
+                        .cause;
 
                     let universe = placeholder.universe;
                     let universe_info = self.regioncx.universe_info(universe);
@@ -454,9 +433,8 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
     ) {
         debug!("report_region_error(fr={:?}, outlived_fr={:?})", fr, outlived_fr);
 
-        let (blame_constraint, path) = self.regioncx.best_blame_constraint(fr, fr_origin, |r| {
-            self.regioncx.provides_universal_region(r, fr, outlived_fr)
-        });
+        let (blame_constraint, path) =
+            self.regioncx.best_blame_constraint(fr, fr_origin, outlived_fr);
         let BlameConstraint { category, cause, variance_info, .. } = blame_constraint;
 
         debug!("report_region_error: category={:?} {:?} {:?}", category, cause, variance_info);
diff --git a/compiler/rustc_borrowck/src/handle_placeholders.rs b/compiler/rustc_borrowck/src/handle_placeholders.rs
index 34599ac55b8..94379cdebf7 100644
--- a/compiler/rustc_borrowck/src/handle_placeholders.rs
+++ b/compiler/rustc_borrowck/src/handle_placeholders.rs
@@ -1,7 +1,6 @@
 //! Logic for lowering higher-kinded outlives constraints
 //! (with placeholders and universes) and turn them into regular
 //! outlives constraints.
-
 use rustc_data_structures::frozen::Frozen;
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::graph::scc;
@@ -10,12 +9,11 @@ use rustc_index::IndexVec;
 use rustc_infer::infer::RegionVariableOrigin;
 use rustc_middle::mir::ConstraintCategory;
 use rustc_middle::ty::{RegionVid, UniverseIndex};
-use tracing::debug;
+use tracing::{debug, trace};
 
 use crate::constraints::{ConstraintSccIndex, OutlivesConstraintSet};
 use crate::consumers::OutlivesConstraint;
 use crate::diagnostics::UniverseInfo;
-use crate::member_constraints::MemberConstraintSet;
 use crate::region_infer::values::{LivenessValues, PlaceholderIndices};
 use crate::region_infer::{ConstraintSccs, RegionDefinition, Representative, TypeTest};
 use crate::ty::VarianceDiagInfo;
@@ -30,7 +28,6 @@ pub(crate) struct LoweredConstraints<'tcx> {
     pub(crate) constraint_sccs: Sccs<RegionVid, ConstraintSccIndex>,
     pub(crate) definitions: Frozen<IndexVec<RegionVid, RegionDefinition<'tcx>>>,
     pub(crate) scc_annotations: IndexVec<ConstraintSccIndex, RegionTracker>,
-    pub(crate) member_constraints: MemberConstraintSet<'tcx, RegionVid>,
     pub(crate) outlives_constraints: Frozen<OutlivesConstraintSet<'tcx>>,
     pub(crate) type_tests: Vec<TypeTest<'tcx>>,
     pub(crate) liveness_constraints: LivenessValues,
@@ -64,18 +61,71 @@ impl scc::Annotations<RegionVid> for SccAnnotations<'_, '_, RegionTracker> {
     type SccIdx = ConstraintSccIndex;
 }
 
+#[derive(Copy, Debug, Clone, PartialEq, Eq)]
+enum PlaceholderReachability {
+    /// This SCC reaches no placeholders.
+    NoPlaceholders,
+    /// This SCC reaches at least one placeholder.
+    Placeholders {
+        /// The largest-universed placeholder we can reach
+        max_universe: (UniverseIndex, RegionVid),
+
+        /// The placeholder with the smallest ID
+        min_placeholder: RegionVid,
+
+        /// The placeholder with the largest ID
+        max_placeholder: RegionVid,
+    },
+}
+
+impl PlaceholderReachability {
+    /// Merge the reachable placeholders of two graph components.
+    fn merge(self, other: PlaceholderReachability) -> PlaceholderReachability {
+        use PlaceholderReachability::*;
+        match (self, other) {
+            (NoPlaceholders, NoPlaceholders) => NoPlaceholders,
+            (NoPlaceholders, p @ Placeholders { .. })
+            | (p @ Placeholders { .. }, NoPlaceholders) => p,
+            (
+                Placeholders {
+                    min_placeholder: min_pl,
+                    max_placeholder: max_pl,
+                    max_universe: max_u,
+                },
+                Placeholders { min_placeholder, max_placeholder, max_universe },
+            ) => Placeholders {
+                min_placeholder: min_pl.min(min_placeholder),
+                max_placeholder: max_pl.max(max_placeholder),
+                max_universe: max_u.max(max_universe),
+            },
+        }
+    }
+
+    fn max_universe(&self) -> Option<(UniverseIndex, RegionVid)> {
+        match self {
+            Self::NoPlaceholders => None,
+            Self::Placeholders { max_universe, .. } => Some(*max_universe),
+        }
+    }
+
+    /// If we have reached placeholders, determine if they can
+    /// be named from this universe.
+    fn can_be_named_by(&self, from: UniverseIndex) -> bool {
+        self.max_universe()
+            .is_none_or(|(max_placeholder_universe, _)| from.can_name(max_placeholder_universe))
+    }
+}
+
 /// An annotation for region graph SCCs that tracks
 /// the values of its elements. This annotates a single SCC.
 #[derive(Copy, Debug, Clone)]
 pub(crate) struct RegionTracker {
-    /// The largest universe of a placeholder reached from this SCC.
-    /// This includes placeholders within this SCC.
-    max_placeholder_universe_reached: UniverseIndex,
+    reachable_placeholders: PlaceholderReachability,
 
     /// The largest universe nameable from this SCC.
     /// It is the smallest nameable universes of all
-    /// existential regions reachable from it.
-    max_nameable_universe: UniverseIndex,
+    /// existential regions reachable from it. Small Rvids are preferred.
+    max_nameable_universe: (UniverseIndex, RegionVid),
 
     /// The representative Region Variable Id for this SCC.
     pub(crate) representative: Representative,
@@ -83,69 +133,82 @@ pub(crate) struct RegionTracker {
 
 impl RegionTracker {
     pub(crate) fn new(rvid: RegionVid, definition: &RegionDefinition<'_>) -> Self {
-        let placeholder_universe =
+        let reachable_placeholders =
             if matches!(definition.origin, NllRegionVariableOrigin::Placeholder(_)) {
-                definition.universe
+                PlaceholderReachability::Placeholders {
+                    max_universe: (definition.universe, rvid),
+                    min_placeholder: rvid,
+                    max_placeholder: rvid,
+                }
             } else {
-                UniverseIndex::ROOT
+                PlaceholderReachability::NoPlaceholders
             };
 
         Self {
-            max_placeholder_universe_reached: placeholder_universe,
-            max_nameable_universe: definition.universe,
+            reachable_placeholders,
+            max_nameable_universe: (definition.universe, rvid),
             representative: Representative::new(rvid, definition),
         }
     }
 
     /// The largest universe this SCC can name. It's the smallest
-    /// largest nameable uninverse of any reachable region.
+    /// largest nameable universe of any reachable region, or
+    /// `max_nameable(r) = min (max_nameable(r') for r' reachable from r)`
     pub(crate) fn max_nameable_universe(self) -> UniverseIndex {
-        self.max_nameable_universe
+        self.max_nameable_universe.0
     }
 
-    fn merge_min_max_seen(&mut self, other: &Self) {
-        self.max_placeholder_universe_reached = std::cmp::max(
-            self.max_placeholder_universe_reached,
-            other.max_placeholder_universe_reached,
-        );
-
-        self.max_nameable_universe =
-            std::cmp::min(self.max_nameable_universe, other.max_nameable_universe);
-    }
-
-    /// Returns `true` if during the annotated SCC reaches a placeholder
-    /// with a universe larger than the smallest nameable universe of any
-    /// reachable existential region.
-    pub(crate) fn has_incompatible_universes(&self) -> bool {
-        self.max_nameable_universe().cannot_name(self.max_placeholder_universe_reached)
+    pub(crate) fn max_placeholder_universe_reached(self) -> UniverseIndex {
+        if let Some((universe, _)) = self.reachable_placeholders.max_universe() {
+            universe
+        } else {
+            UniverseIndex::ROOT
+        }
     }
 
     /// Determine if the tracked universes of the two SCCs are compatible.
     pub(crate) fn universe_compatible_with(&self, other: Self) -> bool {
+        // HACK: We first check whether we can name the highest existential universe
+        // of `other`. This only exists to avoid errors in case that scc already
+        // depends on a placeholder it cannot name itself.
         self.max_nameable_universe().can_name(other.max_nameable_universe())
-            || self.max_nameable_universe().can_name(other.max_placeholder_universe_reached)
+            || other.reachable_placeholders.can_be_named_by(self.max_nameable_universe())
+    }
+
+    /// If this SCC reaches a placeholder it can't name, return it.
+    fn unnameable_placeholder(&self) -> Option<(UniverseIndex, RegionVid)> {
+        self.reachable_placeholders.max_universe().filter(|&(placeholder_universe, _)| {
+            !self.max_nameable_universe().can_name(placeholder_universe)
+        })
     }
 }
 
 impl scc::Annotation for RegionTracker {
-    fn merge_scc(mut self, other: Self) -> Self {
-        self.representative = self.representative.merge_scc(other.representative);
-        self.merge_min_max_seen(&other);
-        self
+    fn merge_scc(self, other: Self) -> Self {
+        trace!("{:?} << {:?}", self.representative, other.representative);
+
+        Self {
+            representative: self.representative.min(other.representative),
+            max_nameable_universe: self.max_nameable_universe.min(other.max_nameable_universe),
+            reachable_placeholders: self.reachable_placeholders.merge(other.reachable_placeholders),
+        }
     }
 
-    fn merge_reached(mut self, other: Self) -> Self {
-        // No update to in-component values, only add seen values.
-        self.merge_min_max_seen(&other);
-        self
+    fn merge_reached(self, other: Self) -> Self {
+        Self {
+            max_nameable_universe: self.max_nameable_universe.min(other.max_nameable_universe),
+            reachable_placeholders: self.reachable_placeholders.merge(other.reachable_placeholders),
+            representative: self.representative,
+        }
     }
 }
 
 /// Determines if the region variable definitions contain
 /// placeholders, and compute them for later use.
-fn region_definitions<'tcx>(
-    universal_regions: &UniversalRegions<'tcx>,
+// FIXME: This is also used by opaque type handling. Move it to a separate file.
+pub(super) fn region_definitions<'tcx>(
     infcx: &BorrowckInferCtxt<'tcx>,
+    universal_regions: &UniversalRegions<'tcx>,
 ) -> (Frozen<IndexVec<RegionVid, RegionDefinition<'tcx>>>, bool) {
     let var_infos = infcx.get_region_var_infos();
     // Create a RegionDefinition for each inference variable. This happens here because
@@ -209,14 +272,13 @@ pub(crate) fn compute_sccs_applying_placeholder_outlives_constraints<'tcx>(
     infcx: &BorrowckInferCtxt<'tcx>,
 ) -> LoweredConstraints<'tcx> {
     let universal_regions = &universal_region_relations.universal_regions;
-    let (definitions, has_placeholders) = region_definitions(universal_regions, infcx);
+    let (definitions, has_placeholders) = region_definitions(infcx, universal_regions);
 
     let MirTypeckRegionConstraints {
         placeholder_indices,
         placeholder_index_to_region: _,
         liveness_constraints,
         mut outlives_constraints,
-        member_constraints,
         universe_causes,
         type_tests,
     } = constraints;
@@ -242,7 +304,6 @@ pub(crate) fn compute_sccs_applying_placeholder_outlives_constraints<'tcx>(
 
         return LoweredConstraints {
             type_tests,
-            member_constraints,
             constraint_sccs,
             scc_annotations: scc_annotations.scc_to_annotation,
             definitions,
@@ -279,7 +340,6 @@ pub(crate) fn compute_sccs_applying_placeholder_outlives_constraints<'tcx>(
         constraint_sccs,
         definitions,
         scc_annotations,
-        member_constraints,
         outlives_constraints: Frozen::freeze(outlives_constraints),
         type_tests,
         liveness_constraints,
@@ -310,28 +370,52 @@ fn rewrite_placeholder_outlives<'tcx>(
 
         let annotation = annotations[scc];
 
-        // If this SCC participates in a universe violation,
-        // e.g. if it reaches a region with a universe smaller than
-        // the largest region reached, add a requirement that it must
-        // outlive `'static`.
-        if annotation.has_incompatible_universes() {
-            // Optimisation opportunity: this will add more constraints than
-            // needed for correctness, since an SCC upstream of another with
-            // a universe violation will "infect" its downstream SCCs to also
-            // outlive static.
-            let scc_representative_outlives_static = OutlivesConstraint {
-                sup: annotation.representative.rvid(),
-                sub: fr_static,
-                category: ConstraintCategory::IllegalUniverse,
-                locations: Locations::All(rustc_span::DUMMY_SP),
-                span: rustc_span::DUMMY_SP,
-                variance_info: VarianceDiagInfo::None,
-                from_closure: false,
-            };
-            outlives_constraints.push(scc_representative_outlives_static);
-            added_constraints = true;
-            debug!("Added {:?}: 'static!", annotation.representative.rvid());
-        }
+        let Some((max_u, max_u_rvid)) = annotation.unnameable_placeholder() else {
+            continue;
+        };
+
+        debug!(
+            "Placeholder universe {max_u:?} is too large for its SCC, represented by {:?}",
+            annotation.representative
+        );
+
+        // We only add one `r: 'static` constraint per SCC, where `r` is the SCC representative.
+        // That constraint is annotated with some placeholder `unnameable` where
+        // `unnameable` is unnameable from `r` and there is a path in the constraint graph
+        // between them.
+        //
+        // There is one exception; if some other region in this SCC can't name `'r`, then
+        // we pick the region with the smallest universe in the SCC, so that a path can
+        // always start in `'r` to find a motivation that isn't cyclic.
+        let blame_to = if annotation.representative.rvid() == max_u_rvid {
+            // Assertion: the region that lowered our universe is an existential one and we are a placeholder!
+
+            // The SCC's representative is not nameable from some region
+            // that ends up in the SCC.
+            let small_universed_rvid = annotation.max_nameable_universe.1;
+            debug!(
+                "{small_universed_rvid:?} lowered our universe to {:?}",
+                annotation.max_nameable_universe()
+            );
+            small_universed_rvid
+        } else {
+            // `max_u_rvid` is not nameable by the SCC's representative.
+            max_u_rvid
+        };
+
+        // FIXME: if we can extract a useful blame span here, future error
+        // reporting and constraint search can be simplified.
+
+        added_constraints = true;
+        outlives_constraints.push(OutlivesConstraint {
+            sup: annotation.representative.rvid(),
+            sub: fr_static,
+            category: ConstraintCategory::OutlivesUnnameablePlaceholder(blame_to),
+            locations: Locations::All(rustc_span::DUMMY_SP),
+            span: rustc_span::DUMMY_SP,
+            variance_info: VarianceDiagInfo::None,
+            from_closure: false,
+        });
     }
     added_constraints
 }
diff --git a/compiler/rustc_borrowck/src/lib.rs b/compiler/rustc_borrowck/src/lib.rs
index d76d6a04e6e..ce78ae203a4 100644
--- a/compiler/rustc_borrowck/src/lib.rs
+++ b/compiler/rustc_borrowck/src/lib.rs
@@ -78,7 +78,6 @@ mod dataflow;
 mod def_use;
 mod diagnostics;
 mod handle_placeholders;
-mod member_constraints;
 mod nll;
 mod path_utils;
 mod place_ext;
@@ -301,7 +300,7 @@ fn do_mir_borrowck<'tcx>(
     def: LocalDefId,
 ) -> PropagatedBorrowCheckResults<'tcx> {
     let tcx = root_cx.tcx;
-    let infcx = BorrowckInferCtxt::new(tcx, def);
+    let infcx = BorrowckInferCtxt::new(tcx, def, root_cx.root_def_id());
     let (input_body, promoted) = tcx.mir_promoted(def);
     let input_body: &Body<'_> = &input_body.borrow();
     let input_promoted: &IndexSlice<_, _> = &promoted.borrow();
@@ -335,9 +334,10 @@ fn do_mir_borrowck<'tcx>(
 
     // Run the MIR type-checker.
     let MirTypeckResults {
-        constraints,
+        mut constraints,
         universal_region_relations,
-        opaque_type_values,
+        region_bound_pairs,
+        known_type_outlives_obligations,
         polonius_context,
     } = type_check::type_check(
         root_cx,
@@ -352,6 +352,17 @@ fn do_mir_borrowck<'tcx>(
         Rc::clone(&location_map),
     );
 
+    let opaque_type_errors = region_infer::opaque_types::handle_opaque_type_uses(
+        root_cx,
+        &infcx,
+        &body,
+        &universal_region_relations,
+        &region_bound_pairs,
+        &known_type_outlives_obligations,
+        &location_map,
+        &mut constraints,
+    );
+
     // Compute non-lexical lifetimes using the constraints computed
     // by typechecking the MIR body.
     let nll::NllOutput {
@@ -375,8 +386,6 @@ fn do_mir_borrowck<'tcx>(
         polonius_context,
     );
 
-    let opaque_type_errors = regioncx.infer_opaque_types(root_cx, &infcx, opaque_type_values);
-
     // Dump MIR results into a file, if that is enabled. This lets us
     // write unit-tests, as well as helping with debugging.
     nll::dump_nll_mir(&infcx, body, &regioncx, &opt_closure_req, &borrow_set);
@@ -581,12 +590,13 @@ fn get_flow_results<'a, 'tcx>(
 
 pub(crate) struct BorrowckInferCtxt<'tcx> {
     pub(crate) infcx: InferCtxt<'tcx>,
-    pub(crate) reg_var_to_origin: RefCell<FxIndexMap<ty::RegionVid, RegionCtxt>>,
+    pub(crate) root_def_id: LocalDefId,
     pub(crate) param_env: ParamEnv<'tcx>,
+    pub(crate) reg_var_to_origin: RefCell<FxIndexMap<ty::RegionVid, RegionCtxt>>,
 }
 
 impl<'tcx> BorrowckInferCtxt<'tcx> {
-    pub(crate) fn new(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Self {
+    pub(crate) fn new(tcx: TyCtxt<'tcx>, def_id: LocalDefId, root_def_id: LocalDefId) -> Self {
         let typing_mode = if tcx.use_typing_mode_borrowck() {
             TypingMode::borrowck(tcx, def_id)
         } else {
@@ -594,7 +604,12 @@ impl<'tcx> BorrowckInferCtxt<'tcx> {
         };
         let infcx = tcx.infer_ctxt().build(typing_mode);
         let param_env = tcx.param_env(def_id);
-        BorrowckInferCtxt { infcx, reg_var_to_origin: RefCell::new(Default::default()), param_env }
+        BorrowckInferCtxt {
+            infcx,
+            root_def_id,
+            reg_var_to_origin: RefCell::new(Default::default()),
+            param_env,
+        }
     }
 
     pub(crate) fn next_region_var<F>(
diff --git a/compiler/rustc_borrowck/src/member_constraints.rs b/compiler/rustc_borrowck/src/member_constraints.rs
deleted file mode 100644
index bdd0f6fe11e..00000000000
--- a/compiler/rustc_borrowck/src/member_constraints.rs
+++ /dev/null
@@ -1,226 +0,0 @@
-use std::hash::Hash;
-use std::ops::Index;
-
-use rustc_data_structures::fx::FxIndexMap;
-use rustc_index::{IndexSlice, IndexVec};
-use rustc_middle::ty::{self, Ty};
-use rustc_span::Span;
-use tracing::instrument;
-
-/// Compactly stores a set of `R0 member of [R1...Rn]` constraints,
-/// indexed by the region `R0`.
-#[derive(Debug)]
-pub(crate) struct MemberConstraintSet<'tcx, R>
-where
-    R: Copy + Eq,
-{
-    /// Stores the first "member" constraint for a given `R0`. This is an
-    /// index into the `constraints` vector below.
-    first_constraints: FxIndexMap<R, NllMemberConstraintIndex>,
-
-    /// Stores the data about each `R0 member of [R1..Rn]` constraint.
-    /// These are organized into a linked list, so each constraint
-    /// contains the index of the next constraint with the same `R0`.
-    constraints: IndexVec<NllMemberConstraintIndex, MemberConstraint<'tcx>>,
-
-    /// Stores the `R1..Rn` regions for *all* sets. For any given
-    /// constraint, we keep two indices so that we can pull out a
-    /// slice.
-    choice_regions: Vec<ty::RegionVid>,
-}
-
-/// Represents a `R0 member of [R1..Rn]` constraint
-#[derive(Debug)]
-pub(crate) struct MemberConstraint<'tcx> {
-    next_constraint: Option<NllMemberConstraintIndex>,
-
-    /// The span where the hidden type was instantiated.
-    pub(crate) definition_span: Span,
-
-    /// The hidden type in which `R0` appears. (Used in error reporting.)
-    pub(crate) hidden_ty: Ty<'tcx>,
-
-    pub(crate) key: ty::OpaqueTypeKey<'tcx>,
-
-    /// The region `R0`.
-    pub(crate) member_region_vid: ty::RegionVid,
-
-    /// Index of `R1` in `choice_regions` vector from `MemberConstraintSet`.
-    start_index: usize,
-
-    /// Index of `Rn` in `choice_regions` vector from `MemberConstraintSet`.
-    end_index: usize,
-}
-
-rustc_index::newtype_index! {
-    #[debug_format = "MemberConstraintIndex({})"]
-    pub(crate) struct NllMemberConstraintIndex {}
-}
-
-impl Default for MemberConstraintSet<'_, ty::RegionVid> {
-    fn default() -> Self {
-        Self {
-            first_constraints: Default::default(),
-            constraints: Default::default(),
-            choice_regions: Default::default(),
-        }
-    }
-}
-
-impl<'tcx> MemberConstraintSet<'tcx, ty::RegionVid> {
-    pub(crate) fn is_empty(&self) -> bool {
-        self.constraints.is_empty()
-    }
-
-    /// Pushes a member constraint into the set.
-    #[instrument(level = "debug", skip(self))]
-    pub(crate) fn add_member_constraint(
-        &mut self,
-        key: ty::OpaqueTypeKey<'tcx>,
-        hidden_ty: Ty<'tcx>,
-        definition_span: Span,
-        member_region_vid: ty::RegionVid,
-        choice_regions: &[ty::RegionVid],
-    ) {
-        let next_constraint = self.first_constraints.get(&member_region_vid).cloned();
-        let start_index = self.choice_regions.len();
-        self.choice_regions.extend(choice_regions);
-        let end_index = self.choice_regions.len();
-        let constraint_index = self.constraints.push(MemberConstraint {
-            next_constraint,
-            member_region_vid,
-            definition_span,
-            hidden_ty,
-            key,
-            start_index,
-            end_index,
-        });
-        self.first_constraints.insert(member_region_vid, constraint_index);
-    }
-}
-
-impl<'tcx, R1> MemberConstraintSet<'tcx, R1>
-where
-    R1: Copy + Hash + Eq,
-{
-    /// Remap the "member region" key using `map_fn`, producing a new
-    /// member constraint set. This is used in the NLL code to map from
-    /// the original `RegionVid` to an scc index. In some cases, we
-    /// may have multiple `R1` values mapping to the same `R2` key -- that
-    /// is ok, the two sets will be merged.
-    pub(crate) fn into_mapped<R2>(
-        self,
-        mut map_fn: impl FnMut(R1) -> R2,
-    ) -> MemberConstraintSet<'tcx, R2>
-    where
-        R2: Copy + Hash + Eq,
-    {
-        // We can re-use most of the original data, just tweaking the
-        // linked list links a bit.
-        //
-        // For example if we had two keys `Ra` and `Rb` that both now
-        // wind up mapped to the same key `S`, we would append the
-        // linked list for `Ra` onto the end of the linked list for
-        // `Rb` (or vice versa) -- this basically just requires
-        // rewriting the final link from one list to point at the other
-        // other (see `append_list`).
-
-        let MemberConstraintSet { first_constraints, mut constraints, choice_regions } = self;
-
-        let mut first_constraints2 = FxIndexMap::default();
-        first_constraints2.reserve(first_constraints.len());
-
-        for (r1, start1) in first_constraints {
-            let r2 = map_fn(r1);
-            if let Some(&start2) = first_constraints2.get(&r2) {
-                append_list(&mut constraints, start1, start2);
-            }
-            first_constraints2.insert(r2, start1);
-        }
-
-        MemberConstraintSet { first_constraints: first_constraints2, constraints, choice_regions }
-    }
-}
-
-impl<'tcx, R> MemberConstraintSet<'tcx, R>
-where
-    R: Copy + Hash + Eq,
-{
-    pub(crate) fn all_indices(&self) -> impl Iterator<Item = NllMemberConstraintIndex> {
-        self.constraints.indices()
-    }
-
-    /// Iterate down the constraint indices associated with a given
-    /// peek-region. You can then use `choice_regions` and other
-    /// methods to access data.
-    pub(crate) fn indices(
-        &self,
-        member_region_vid: R,
-    ) -> impl Iterator<Item = NllMemberConstraintIndex> {
-        let mut next = self.first_constraints.get(&member_region_vid).cloned();
-        std::iter::from_fn(move || -> Option<NllMemberConstraintIndex> {
-            if let Some(current) = next {
-                next = self.constraints[current].next_constraint;
-                Some(current)
-            } else {
-                None
-            }
-        })
-    }
-
-    /// Returns the "choice regions" for a given member
-    /// constraint. This is the `R1..Rn` from a constraint like:
-    ///
-    /// ```text
-    /// R0 member of [R1..Rn]
-    /// ```
-    pub(crate) fn choice_regions(&self, pci: NllMemberConstraintIndex) -> &[ty::RegionVid] {
-        let MemberConstraint { start_index, end_index, .. } = &self.constraints[pci];
-        &self.choice_regions[*start_index..*end_index]
-    }
-}
-
-impl<'tcx, R> Index<NllMemberConstraintIndex> for MemberConstraintSet<'tcx, R>
-where
-    R: Copy + Eq,
-{
-    type Output = MemberConstraint<'tcx>;
-
-    fn index(&self, i: NllMemberConstraintIndex) -> &MemberConstraint<'tcx> {
-        &self.constraints[i]
-    }
-}
-
-/// Given a linked list starting at `source_list` and another linked
-/// list starting at `target_list`, modify `target_list` so that it is
-/// followed by `source_list`.
-///
-/// Before:
-///
-/// ```text
-/// target_list: A -> B -> C -> (None)
-/// source_list: D -> E -> F -> (None)
-/// ```
-///
-/// After:
-///
-/// ```text
-/// target_list: A -> B -> C -> D -> E -> F -> (None)
-/// ```
-fn append_list(
-    constraints: &mut IndexSlice<NllMemberConstraintIndex, MemberConstraint<'_>>,
-    target_list: NllMemberConstraintIndex,
-    source_list: NllMemberConstraintIndex,
-) {
-    let mut p = target_list;
-    loop {
-        let r = &mut constraints[p];
-        match r.next_constraint {
-            Some(q) => p = q,
-            None => {
-                r.next_constraint = Some(source_list);
-                return;
-            }
-        }
-    }
-}
diff --git a/compiler/rustc_borrowck/src/region_infer/graphviz.rs b/compiler/rustc_borrowck/src/region_infer/graphviz.rs
index b2f67c43125..526e1850c2e 100644
--- a/compiler/rustc_borrowck/src/region_infer/graphviz.rs
+++ b/compiler/rustc_borrowck/src/region_infer/graphviz.rs
@@ -12,9 +12,13 @@ use rustc_middle::ty::UniverseIndex;
 use super::*;
 
 fn render_outlives_constraint(constraint: &OutlivesConstraint<'_>) -> String {
-    match constraint.locations {
-        Locations::All(_) => "All(...)".to_string(),
-        Locations::Single(loc) => format!("{loc:?}"),
+    if let ConstraintCategory::OutlivesUnnameablePlaceholder(unnameable) = constraint.category {
+        format!("{unnameable:?} unnameable")
+    } else {
+        match constraint.locations {
+            Locations::All(_) => "All(...)".to_string(),
+            Locations::Single(loc) => format!("{loc:?}"),
+        }
     }
 }
 
diff --git a/compiler/rustc_borrowck/src/region_infer/mod.rs b/compiler/rustc_borrowck/src/region_infer/mod.rs
index b0c31ac9601..9990f4cb3f2 100644
--- a/compiler/rustc_borrowck/src/region_infer/mod.rs
+++ b/compiler/rustc_borrowck/src/region_infer/mod.rs
@@ -1,11 +1,9 @@
-use std::cell::OnceCell;
 use std::collections::VecDeque;
 use std::rc::Rc;
 
-use rustc_data_structures::binary_search_util;
 use rustc_data_structures::frozen::Frozen;
 use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
-use rustc_data_structures::graph::scc::{self, Sccs};
+use rustc_data_structures::graph::scc::Sccs;
 use rustc_errors::Diag;
 use rustc_hir::def_id::CRATE_DEF_ID;
 use rustc_index::IndexVec;
@@ -24,15 +22,13 @@ use rustc_span::hygiene::DesugaringKind;
 use rustc_span::{DUMMY_SP, Span};
 use tracing::{Level, debug, enabled, instrument, trace};
 
-use crate::constraints::graph::{self, NormalConstraintGraph, RegionGraph};
+use crate::constraints::graph::NormalConstraintGraph;
 use crate::constraints::{ConstraintSccIndex, OutlivesConstraint, OutlivesConstraintSet};
 use crate::dataflow::BorrowIndex;
 use crate::diagnostics::{RegionErrorKind, RegionErrors, UniverseInfo};
 use crate::handle_placeholders::{LoweredConstraints, RegionTracker};
-use crate::member_constraints::{MemberConstraintSet, NllMemberConstraintIndex};
 use crate::polonius::LiveLoans;
 use crate::polonius::legacy::PoloniusOutput;
-use crate::region_infer::reverse_sccs::ReverseSccGraph;
 use crate::region_infer::values::{LivenessValues, RegionElement, RegionValues, ToElementIndex};
 use crate::type_check::Locations;
 use crate::type_check::free_region_relations::UniversalRegionRelations;
@@ -78,18 +74,6 @@ impl Representative {
     }
 }
 
-impl scc::Annotation for Representative {
-    fn merge_scc(self, other: Self) -> Self {
-        // Just pick the smallest one. Note that we order by tag first!
-        std::cmp::min(self, other)
-    }
-
-    // For reachability, we do nothing since the representative doesn't change.
-    fn merge_reached(self, _other: Self) -> Self {
-        self
-    }
-}
-
 pub(crate) type ConstraintSccs = Sccs<RegionVid, ConstraintSccIndex>;
 
 pub struct RegionInferenceContext<'tcx> {
@@ -120,20 +104,6 @@ pub struct RegionInferenceContext<'tcx> {
 
     scc_annotations: IndexVec<ConstraintSccIndex, RegionTracker>,
 
-    /// Reverse of the SCC constraint graph --  i.e., an edge `A -> B` exists if
-    /// `B: A`. This is used to compute the universal regions that are required
-    /// to outlive a given SCC.
-    rev_scc_graph: OnceCell<ReverseSccGraph>,
-
-    /// The "R0 member of [R1..Rn]" constraints, indexed by SCC.
-    member_constraints: Rc<MemberConstraintSet<'tcx, ConstraintSccIndex>>,
-
-    /// Records the member constraints that we applied to each scc.
-    /// This is useful for error reporting. Once constraint
-    /// propagation is done, this vector is sorted according to
-    /// `member_region_scc`.
-    member_constraints_applied: Vec<AppliedMemberConstraint>,
-
     /// Map universe indexes to information on why we created it.
     universe_causes: FxIndexMap<ty::UniverseIndex, UniverseInfo<'tcx>>,
 
@@ -150,32 +120,6 @@ pub struct RegionInferenceContext<'tcx> {
     universal_region_relations: Frozen<UniversalRegionRelations<'tcx>>,
 }
 
-/// Each time that `apply_member_constraint` is successful, it appends
-/// one of these structs to the `member_constraints_applied` field.
-/// This is used in error reporting to trace out what happened.
-///
-/// The way that `apply_member_constraint` works is that it effectively
-/// adds a new lower bound to the SCC it is analyzing: so you wind up
-/// with `'R: 'O` where `'R` is the pick-region and `'O` is the
-/// minimal viable option.
-#[derive(Debug)]
-pub(crate) struct AppliedMemberConstraint {
-    /// The SCC that was affected. (The "member region".)
-    ///
-    /// The vector if `AppliedMemberConstraint` elements is kept sorted
-    /// by this field.
-    pub(crate) member_region_scc: ConstraintSccIndex,
-
-    /// The "best option" that `apply_member_constraint` found -- this was
-    /// added as an "ad-hoc" lower-bound to `member_region_scc`.
-    pub(crate) min_choice: ty::RegionVid,
-
-    /// The "member constraint index" -- we can find out details about
-    /// the constraint from
-    /// `set.member_constraints[member_constraint_index]`.
-    pub(crate) member_constraint_index: NllMemberConstraintIndex,
-}
-
 #[derive(Debug)]
 pub(crate) struct RegionDefinition<'tcx> {
     /// What kind of variable is this -- a free region? existential
@@ -268,7 +212,6 @@ enum Trace<'a, 'tcx> {
     StartRegion,
     FromGraph(&'a OutlivesConstraint<'tcx>),
     FromStatic(RegionVid),
-    FromMember(RegionVid, RegionVid, Span),
     NotVisited,
 }
 
@@ -363,7 +306,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             liveness_constraints,
             universe_causes,
             placeholder_indices,
-            member_constraints,
         } = lowered_constraints;
 
         debug!("universal_regions: {:#?}", universal_region_relations.universal_regions);
@@ -385,9 +327,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             scc_values.merge_liveness(scc, region, &liveness_constraints);
         }
 
-        let member_constraints =
-            Rc::new(member_constraints.into_mapped(|r| constraint_sccs.scc(r)));
-
         let mut result = Self {
             definitions,
             liveness_constraints,
@@ -395,9 +334,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             constraint_graph,
             constraint_sccs,
             scc_annotations,
-            rev_scc_graph: OnceCell::new(),
-            member_constraints,
-            member_constraints_applied: Vec::new(),
             universe_causes,
             scc_values,
             type_tests,
@@ -550,19 +486,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         self.scc_values.placeholders_contained_in(scc)
     }
 
-    /// Once region solving has completed, this function will return the member constraints that
-    /// were applied to the value of a given SCC `scc`. See `AppliedMemberConstraint`.
-    pub(crate) fn applied_member_constraints(
-        &self,
-        scc: ConstraintSccIndex,
-    ) -> &[AppliedMemberConstraint] {
-        binary_search_util::binary_search_slice(
-            &self.member_constraints_applied,
-            |applied| applied.member_region_scc,
-            &scc,
-        )
-    }
-
     /// Performs region inference and report errors if we see any
     /// unsatisfiable constraints. If this is a closure, returns the
     /// region requirements to propagate to our creator, if any.
@@ -607,12 +530,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
 
         debug!(?errors_buffer);
 
-        if errors_buffer.is_empty() {
-            self.check_member_constraints(infcx, &mut errors_buffer);
-        }
-
-        debug!(?errors_buffer);
-
         let outlives_requirements = outlives_requirements.unwrap_or_default();
 
         if outlives_requirements.is_empty() {
@@ -642,146 +559,15 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         });
 
         // To propagate constraints, we walk the DAG induced by the
-        // SCC. For each SCC, we visit its successors and compute
+        // SCC. For each SCC `A`, we visit its successors and compute
         // their values, then we union all those values to get our
         // own.
-        for scc in self.constraint_sccs.all_sccs() {
-            self.compute_value_for_scc(scc);
-        }
-
-        // Sort the applied member constraints so we can binary search
-        // through them later.
-        self.member_constraints_applied.sort_by_key(|applied| applied.member_region_scc);
-    }
-
-    /// Computes the value of the SCC `scc_a`, which has not yet been
-    /// computed, by unioning the values of its successors.
-    /// Assumes that all successors have been computed already
-    /// (which is assured by iterating over SCCs in dependency order).
-    #[instrument(skip(self), level = "debug")]
-    fn compute_value_for_scc(&mut self, scc_a: ConstraintSccIndex) {
-        // Walk each SCC `B` such that `A: B`...
-        for &scc_b in self.constraint_sccs.successors(scc_a) {
-            debug!(?scc_b);
-            self.scc_values.add_region(scc_a, scc_b);
-        }
-
-        // Now take member constraints into account.
-        let member_constraints = Rc::clone(&self.member_constraints);
-        for m_c_i in member_constraints.indices(scc_a) {
-            self.apply_member_constraint(scc_a, m_c_i, member_constraints.choice_regions(m_c_i));
-        }
-
-        debug!(value = ?self.scc_values.region_value_str(scc_a));
-    }
-
-    /// Invoked for each `R0 member of [R1..Rn]` constraint.
-    ///
-    /// `scc` is the SCC containing R0, and `choice_regions` are the
-    /// `R1..Rn` regions -- they are always known to be universal
-    /// regions (and if that's not true, we just don't attempt to
-    /// enforce the constraint).
-    ///
-    /// The current value of `scc` at the time the method is invoked
-    /// is considered a *lower bound*. If possible, we will modify
-    /// the constraint to set it equal to one of the option regions.
-    /// If we make any changes, returns true, else false.
-    ///
-    /// This function only adds the member constraints to the region graph,
-    /// it does not check them. They are later checked in
-    /// `check_member_constraints` after the region graph has been computed.
-    #[instrument(skip(self, member_constraint_index), level = "debug")]
-    fn apply_member_constraint(
-        &mut self,
-        scc: ConstraintSccIndex,
-        member_constraint_index: NllMemberConstraintIndex,
-        choice_regions: &[ty::RegionVid],
-    ) {
-        // Create a mutable vector of the options. We'll try to winnow
-        // them down.
-        let mut choice_regions: Vec<ty::RegionVid> = choice_regions.to_vec();
-
-        // Convert to the SCC representative: sometimes we have inference
-        // variables in the member constraint that wind up equated with
-        // universal regions. The scc representative is the minimal numbered
-        // one from the corresponding scc so it will be the universal region
-        // if one exists.
-        for c_r in &mut choice_regions {
-            let scc = self.constraint_sccs.scc(*c_r);
-            *c_r = self.scc_representative(scc);
-        }
-
-        // If the member region lives in a higher universe, we currently choose
-        // the most conservative option by leaving it unchanged.
-        if !self.max_nameable_universe(scc).is_root() {
-            return;
-        }
-
-        // The existing value for `scc` is a lower-bound. This will
-        // consist of some set `{P} + {LB}` of points `{P}` and
-        // lower-bound free regions `{LB}`. As each choice region `O`
-        // is a free region, it will outlive the points. But we can
-        // only consider the option `O` if `O: LB`.
-        choice_regions.retain(|&o_r| {
-            self.scc_values
-                .universal_regions_outlived_by(scc)
-                .all(|lb| self.universal_region_relations.outlives(o_r, lb))
-        });
-        debug!(?choice_regions, "after lb");
-
-        // Now find all the *upper bounds* -- that is, each UB is a
-        // free region that must outlive the member region `R0` (`UB:
-        // R0`). Therefore, we need only keep an option `O` if `UB: O`
-        // for all UB.
-        let universal_region_relations = &self.universal_region_relations;
-        for ub in self.reverse_scc_graph().upper_bounds(scc) {
-            debug!(?ub);
-            choice_regions.retain(|&o_r| universal_region_relations.outlives(ub, o_r));
-        }
-        debug!(?choice_regions, "after ub");
-
-        // At this point we can pick any member of `choice_regions` and would like to choose
-        // it to be a small as possible. To avoid potential non-determinism we will pick the
-        // smallest such choice.
-        //
-        // Because universal regions are only partially ordered (i.e, not every two regions are
-        // comparable), we will ignore any region that doesn't compare to all others when picking
-        // the minimum choice.
-        //
-        // For example, consider `choice_regions = ['static, 'a, 'b, 'c, 'd, 'e]`, where
-        // `'static: 'a, 'static: 'b, 'a: 'c, 'b: 'c, 'c: 'd, 'c: 'e`.
-        // `['d, 'e]` are ignored because they do not compare - the same goes for `['a, 'b]`.
-        let totally_ordered_subset = choice_regions.iter().copied().filter(|&r1| {
-            choice_regions.iter().all(|&r2| {
-                self.universal_region_relations.outlives(r1, r2)
-                    || self.universal_region_relations.outlives(r2, r1)
-            })
-        });
-        // Now we're left with `['static, 'c]`. Pick `'c` as the minimum!
-        let Some(min_choice) = totally_ordered_subset.reduce(|r1, r2| {
-            let r1_outlives_r2 = self.universal_region_relations.outlives(r1, r2);
-            let r2_outlives_r1 = self.universal_region_relations.outlives(r2, r1);
-            match (r1_outlives_r2, r2_outlives_r1) {
-                (true, true) => r1.min(r2),
-                (true, false) => r2,
-                (false, true) => r1,
-                (false, false) => bug!("incomparable regions in total order"),
+        for scc_a in self.constraint_sccs.all_sccs() {
+            // Walk each SCC `B` such that `A: B`...
+            for &scc_b in self.constraint_sccs.successors(scc_a) {
+                debug!(?scc_b);
+                self.scc_values.add_region(scc_a, scc_b);
             }
-        }) else {
-            debug!("no unique minimum choice");
-            return;
-        };
-
-        // As we require `'scc: 'min_choice`, we have definitely already computed
-        // its `scc_values` at this point.
-        let min_choice_scc = self.constraint_sccs.scc(min_choice);
-        debug!(?min_choice, ?min_choice_scc);
-        if self.scc_values.add_region(scc, min_choice_scc) {
-            self.member_constraints_applied.push(AppliedMemberConstraint {
-                member_region_scc: scc,
-                min_choice,
-                member_constraint_index,
-            });
         }
     }
 
@@ -1487,11 +1273,9 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         {
             debug!("try_propagate_universal_region_error: fr_minus={:?}", fr_minus);
 
-            let blame_span_category = self.find_outlives_blame_span(
-                longer_fr,
-                NllRegionVariableOrigin::FreeRegion,
-                shorter_fr,
-            );
+            let blame_constraint = self
+                .best_blame_constraint(longer_fr, NllRegionVariableOrigin::FreeRegion, shorter_fr)
+                .0;
 
             // Grow `shorter_fr` until we find some non-local regions. (We
             // always will.)  We'll call them `shorter_fr+` -- they're ever
@@ -1504,8 +1288,8 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                 propagated_outlives_requirements.push(ClosureOutlivesRequirement {
                     subject: ClosureOutlivesSubject::Region(fr_minus),
                     outlived_free_region: fr,
-                    blame_span: blame_span_category.1.span,
-                    category: blame_span_category.0,
+                    blame_span: blame_constraint.cause.span,
+                    category: blame_constraint.category,
                 });
             }
             return RegionRelationCheckResult::Propagated;
@@ -1544,118 +1328,67 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         }
     }
 
-    #[instrument(level = "debug", skip(self, infcx, errors_buffer))]
-    fn check_member_constraints(
-        &self,
-        infcx: &InferCtxt<'tcx>,
-        errors_buffer: &mut RegionErrors<'tcx>,
-    ) {
-        let member_constraints = Rc::clone(&self.member_constraints);
-        for m_c_i in member_constraints.all_indices() {
-            debug!(?m_c_i);
-            let m_c = &member_constraints[m_c_i];
-            let member_region_vid = m_c.member_region_vid;
-            debug!(
-                ?member_region_vid,
-                value = ?self.region_value_str(member_region_vid),
-            );
-            let choice_regions = member_constraints.choice_regions(m_c_i);
-            debug!(?choice_regions);
-
-            // Did the member region wind up equal to any of the option regions?
-            if let Some(o) =
-                choice_regions.iter().find(|&&o_r| self.eval_equal(o_r, m_c.member_region_vid))
-            {
-                debug!("evaluated as equal to {:?}", o);
-                continue;
-            }
-
-            // If not, report an error.
-            let member_region = ty::Region::new_var(infcx.tcx, member_region_vid);
-            errors_buffer.push(RegionErrorKind::UnexpectedHiddenRegion {
-                span: m_c.definition_span,
-                hidden_ty: m_c.hidden_ty,
-                key: m_c.key,
-                member_region,
-            });
-        }
-    }
-
-    /// We have a constraint `fr1: fr2` that is not satisfied, where
-    /// `fr2` represents some universal region. Here, `r` is some
-    /// region where we know that `fr1: r` and this function has the
-    /// job of determining whether `r` is "to blame" for the fact that
-    /// `fr1: fr2` is required.
-    ///
-    /// This is true under two conditions:
-    ///
-    /// - `r == fr2`
-    /// - `fr2` is `'static` and `r` is some placeholder in a universe
-    ///   that cannot be named by `fr1`; in that case, we will require
-    ///   that `fr1: 'static` because it is the only way to `fr1: r` to
-    ///   be satisfied. (See `add_incompatible_universe`.)
-    pub(crate) fn provides_universal_region(
+    pub(crate) fn constraint_path_between_regions(
         &self,
-        r: RegionVid,
-        fr1: RegionVid,
-        fr2: RegionVid,
-    ) -> bool {
-        debug!("provides_universal_region(r={:?}, fr1={:?}, fr2={:?})", r, fr1, fr2);
-        let result = {
-            r == fr2 || {
-                fr2 == self.universal_regions().fr_static && self.cannot_name_placeholder(fr1, r)
-            }
-        };
-        debug!("provides_universal_region: result = {:?}", result);
-        result
-    }
-
-    /// If `r2` represents a placeholder region, then this returns
-    /// `true` if `r1` cannot name that placeholder in its
-    /// value; otherwise, returns `false`.
-    pub(crate) fn cannot_name_placeholder(&self, r1: RegionVid, r2: RegionVid) -> bool {
-        match self.definitions[r2].origin {
-            NllRegionVariableOrigin::Placeholder(placeholder) => {
-                let r1_universe = self.definitions[r1].universe;
-                debug!(
-                    "cannot_name_value_of: universe1={r1_universe:?} placeholder={:?}",
-                    placeholder
-                );
-                r1_universe.cannot_name(placeholder.universe)
-            }
-
-            NllRegionVariableOrigin::FreeRegion | NllRegionVariableOrigin::Existential { .. } => {
-                false
-            }
+        from_region: RegionVid,
+        to_region: RegionVid,
+    ) -> Option<Vec<OutlivesConstraint<'tcx>>> {
+        if from_region == to_region {
+            bug!("Tried to find a path between {from_region:?} and itself!");
         }
-    }
-
-    /// Finds a good `ObligationCause` to blame for the fact that `fr1` outlives `fr2`.
-    pub(crate) fn find_outlives_blame_span(
-        &self,
-        fr1: RegionVid,
-        fr1_origin: NllRegionVariableOrigin,
-        fr2: RegionVid,
-    ) -> (ConstraintCategory<'tcx>, ObligationCause<'tcx>) {
-        let BlameConstraint { category, cause, .. } = self
-            .best_blame_constraint(fr1, fr1_origin, |r| self.provides_universal_region(r, fr1, fr2))
-            .0;
-        (category, cause)
+        self.constraint_path_to(from_region, |to| to == to_region, true).map(|o| o.0)
     }
 
     /// Walks the graph of constraints (where `'a: 'b` is considered
-    /// an edge `'a -> 'b`) to find all paths from `from_region` to
-    /// `to_region`. The paths are accumulated into the vector
-    /// `results`. The paths are stored as a series of
-    /// `ConstraintIndex` values -- in other words, a list of *edges*.
+    /// an edge `'a -> 'b`) to find a path from `from_region` to
+    /// `to_region`.
     ///
     /// Returns: a series of constraints as well as the region `R`
     /// that passed the target test.
+    /// If `include_static_outlives_all` is `true`, then the synthetic
+    /// outlives constraints `'static -> a` for every region `a` are
+    /// considered in the search, otherwise they are ignored.
     #[instrument(skip(self, target_test), ret)]
-    pub(crate) fn find_constraint_paths_between_regions(
+    pub(crate) fn constraint_path_to(
+        &self,
+        from_region: RegionVid,
+        target_test: impl Fn(RegionVid) -> bool,
+        include_placeholder_static: bool,
+    ) -> Option<(Vec<OutlivesConstraint<'tcx>>, RegionVid)> {
+        self.find_constraint_path_between_regions_inner(
+            true,
+            from_region,
+            &target_test,
+            include_placeholder_static,
+        )
+        .or_else(|| {
+            self.find_constraint_path_between_regions_inner(
+                false,
+                from_region,
+                &target_test,
+                include_placeholder_static,
+            )
+        })
+    }
+
+    /// The constraints we get from equating the hidden type of each use of an opaque
+    /// with its final concrete type may end up getting preferred over other, potentially
+    /// longer constraint paths.
+    ///
+    /// Given that we compute the final concrete type by relying on this existing constraint
+    /// path, this can easily end up hiding the actual reason for why we require these regions
+    /// to be equal.
+    ///
+    /// To handle this, we first look at the path while ignoring these constraints and then
+    /// retry while considering them. This is not perfect, as the `from_region` may have already
+    /// been partially related to its argument region, so while we rely on a member constraint
+    /// to get a complete path, the most relevant step of that path already existed before then.
+    fn find_constraint_path_between_regions_inner(
         &self,
+        ignore_opaque_type_constraints: bool,
         from_region: RegionVid,
         target_test: impl Fn(RegionVid) -> bool,
+        include_placeholder_static: bool,
     ) -> Option<(Vec<OutlivesConstraint<'tcx>>, RegionVid)> {
         let mut context = IndexVec::from_elem(Trace::NotVisited, &self.definitions);
         context[from_region] = Trace::StartRegion;
@@ -1670,7 +1403,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
 
         while let Some(r) = deque.pop_front() {
             debug!(
-                "find_constraint_paths_between_regions: from_region={:?} r={:?} value={}",
+                "constraint_path_to: from_region={:?} r={:?} value={}",
                 from_region,
                 r,
                 self.region_value_str(r),
@@ -1704,20 +1437,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                             result.push(c);
                         }
 
-                        Trace::FromMember(sup, sub, span) => {
-                            let c = OutlivesConstraint {
-                                sup,
-                                sub,
-                                locations: Locations::All(span),
-                                span,
-                                category: ConstraintCategory::OpaqueType,
-                                variance_info: ty::VarianceDiagInfo::default(),
-                                from_closure: false,
-                            };
-                            p = c.sup;
-                            result.push(c);
-                        }
-
                         Trace::StartRegion => {
                             result.reverse();
                             return Some((result, r));
@@ -1756,23 +1475,24 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                 let edges = self.constraint_graph.outgoing_edges_from_graph(r, &self.constraints);
                 // This loop can be hot.
                 for constraint in edges {
-                    if matches!(constraint.category, ConstraintCategory::IllegalUniverse) {
-                        debug!("Ignoring illegal universe constraint: {constraint:?}");
-                        continue;
+                    match constraint.category {
+                        ConstraintCategory::OutlivesUnnameablePlaceholder(_)
+                            if !include_placeholder_static =>
+                        {
+                            debug!("Ignoring illegal placeholder constraint: {constraint:?}");
+                            continue;
+                        }
+                        ConstraintCategory::OpaqueType if ignore_opaque_type_constraints => {
+                            debug!("Ignoring member constraint: {constraint:?}");
+                            continue;
+                        }
+                        _ => {}
                     }
+
                     debug_assert_eq!(constraint.sup, r);
                     handle_trace(constraint.sub, Trace::FromGraph(constraint));
                 }
             }
-
-            // Member constraints can also give rise to `'r: 'x` edges that
-            // were not part of the graph initially, so watch out for those.
-            // (But they are extremely rare; this loop is very cold.)
-            for constraint in self.applied_member_constraints(self.constraint_sccs.scc(r)) {
-                let sub = constraint.min_choice;
-                let p_c = &self.member_constraints[constraint.member_constraint_index];
-                handle_trace(sub, Trace::FromMember(r, sub, p_c.definition_span));
-            }
         }
 
         None
@@ -1783,37 +1503,10 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     pub(crate) fn find_sub_region_live_at(&self, fr1: RegionVid, location: Location) -> RegionVid {
         trace!(scc = ?self.constraint_sccs.scc(fr1));
         trace!(universe = ?self.max_nameable_universe(self.constraint_sccs.scc(fr1)));
-        self.find_constraint_paths_between_regions(fr1, |r| {
-            // First look for some `r` such that `fr1: r` and `r` is live at `location`
+        self.constraint_path_to(fr1, |r| {
             trace!(?r, liveness_constraints=?self.liveness_constraints.pretty_print_live_points(r));
             self.liveness_constraints.is_live_at(r, location)
-        })
-        .or_else(|| {
-            // If we fail to find that, we may find some `r` such that
-            // `fr1: r` and `r` is a placeholder from some universe
-            // `fr1` cannot name. This would force `fr1` to be
-            // `'static`.
-            self.find_constraint_paths_between_regions(fr1, |r| {
-                self.cannot_name_placeholder(fr1, r)
-            })
-        })
-        .or_else(|| {
-            // If we fail to find THAT, it may be that `fr1` is a
-            // placeholder that cannot "fit" into its SCC. In that
-            // case, there should be some `r` where `fr1: r` and `fr1` is a
-            // placeholder that `r` cannot name. We can blame that
-            // edge.
-            //
-            // Remember that if `R1: R2`, then the universe of R1
-            // must be able to name the universe of R2, because R2 will
-            // be at least `'empty(Universe(R2))`, and `R1` must be at
-            // larger than that.
-            self.find_constraint_paths_between_regions(fr1, |r| {
-                self.cannot_name_placeholder(r, fr1)
-            })
-        })
-        .map(|(_path, r)| r)
-        .unwrap()
+        }, true).unwrap().1
     }
 
     /// Get the region outlived by `longer_fr` and live at `element`.
@@ -1857,22 +1550,38 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     /// creating a constraint path that forces `R` to outlive
     /// `from_region`, and then finding the best choices within that
     /// path to blame.
-    #[instrument(level = "debug", skip(self, target_test))]
+    #[instrument(level = "debug", skip(self))]
     pub(crate) fn best_blame_constraint(
         &self,
         from_region: RegionVid,
         from_region_origin: NllRegionVariableOrigin,
-        target_test: impl Fn(RegionVid) -> bool,
+        to_region: RegionVid,
     ) -> (BlameConstraint<'tcx>, Vec<OutlivesConstraint<'tcx>>) {
-        // Find all paths
-        let (path, target_region) = self
-            .find_constraint_paths_between_regions(from_region, target_test)
-            .or_else(|| {
-                self.find_constraint_paths_between_regions(from_region, |r| {
-                    self.cannot_name_placeholder(from_region, r)
-                })
-            })
-            .unwrap();
+        assert!(from_region != to_region, "Trying to blame a region for itself!");
+
+        let path = self.constraint_path_between_regions(from_region, to_region).unwrap();
+
+        // If we are passing through a constraint added because we reached an unnameable placeholder `'unnameable`,
+        // redirect search towards `'unnameable`.
+        let due_to_placeholder_outlives = path.iter().find_map(|c| {
+            if let ConstraintCategory::OutlivesUnnameablePlaceholder(unnameable) = c.category {
+                Some(unnameable)
+            } else {
+                None
+            }
+        });
+
+        // Edge case: it's possible that `'from_region` is an unnameable placeholder.
+        let path = if let Some(unnameable) = due_to_placeholder_outlives
+            && unnameable != from_region
+        {
+            // We ignore the extra edges due to unnameable placeholders to get
+            // an explanation that was present in the original constraint graph.
+            self.constraint_path_to(from_region, |r| r == unnameable, false).unwrap().0
+        } else {
+            path
+        };
+
         debug!(
             "path={:#?}",
             path.iter()
@@ -1980,7 +1689,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                 ConstraintCategory::Cast {
                     unsize_to: Some(unsize_ty),
                     is_implicit_coercion: true,
-                } if target_region == self.universal_regions().fr_static
+                } if to_region == self.universal_regions().fr_static
                     // Mirror the note's condition, to minimize how often this diverts blame.
                     && let ty::Adt(_, args) = unsize_ty.kind()
                     && args.iter().any(|arg| arg.as_type().is_some_and(|ty| ty.is_trait()))
@@ -2018,7 +1727,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                 // specific, and are not used for relations that would make sense to blame.
                 ConstraintCategory::BoringNoLocation => 6,
                 // Do not blame internal constraints.
-                ConstraintCategory::IllegalUniverse => 7,
+                ConstraintCategory::OutlivesUnnameablePlaceholder(_) => 7,
                 ConstraintCategory::Internal => 8,
             };
 
@@ -2055,6 +1764,14 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             path[best_choice]
         };
 
+        assert!(
+            !matches!(
+                best_constraint.category,
+                ConstraintCategory::OutlivesUnnameablePlaceholder(_)
+            ),
+            "Illegal placeholder constraint blamed; should have redirected to other region relation"
+        );
+
         let blame_constraint = BlameConstraint {
             category: best_constraint.category,
             from_closure: best_constraint.from_closure,
@@ -2104,11 +1821,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         &self.constraint_sccs
     }
 
-    /// Access to the region graph, built from the outlives constraints.
-    pub(crate) fn region_graph(&self) -> RegionGraph<'_, 'tcx, graph::Normal> {
-        self.constraint_graph.region_graph(&self.constraints, self.universal_regions().fr_static)
-    }
-
     /// Returns the representative `RegionVid` for a given SCC.
     /// See `RegionTracker` for how a region variable ID is chosen.
     ///
diff --git a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
deleted file mode 100644
index 23c4554aa15..00000000000
--- a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
+++ /dev/null
@@ -1,299 +0,0 @@
-use rustc_data_structures::fx::FxIndexMap;
-use rustc_infer::infer::{InferCtxt, NllRegionVariableOrigin};
-use rustc_macros::extension;
-use rustc_middle::ty::{
-    self, DefiningScopeKind, OpaqueHiddenType, OpaqueTypeKey, Ty, TyCtxt, TypeFoldable,
-    TypeVisitableExt, fold_regions,
-};
-use rustc_span::Span;
-use rustc_trait_selection::opaque_types::{
-    InvalidOpaqueTypeArgs, check_opaque_type_parameter_valid,
-};
-use tracing::{debug, instrument};
-
-use super::RegionInferenceContext;
-use crate::BorrowCheckRootCtxt;
-use crate::session_diagnostics::LifetimeMismatchOpaqueParam;
-use crate::universal_regions::RegionClassification;
-
-pub(crate) enum DeferredOpaqueTypeError<'tcx> {
-    InvalidOpaqueTypeArgs(InvalidOpaqueTypeArgs<'tcx>),
-    LifetimeMismatchOpaqueParam(LifetimeMismatchOpaqueParam<'tcx>),
-}
-
-impl<'tcx> RegionInferenceContext<'tcx> {
-    /// Resolve any opaque types that were encountered while borrow checking
-    /// this item. This is then used to get the type in the `type_of` query.
-    ///
-    /// For example consider `fn f<'a>(x: &'a i32) -> impl Sized + 'a { x }`.
-    /// This is lowered to give HIR something like
-    ///
-    /// type f<'a>::_Return<'_x> = impl Sized + '_x;
-    /// fn f<'a>(x: &'a i32) -> f<'a>::_Return<'a> { x }
-    ///
-    /// When checking the return type record the type from the return and the
-    /// type used in the return value. In this case they might be `_Return<'1>`
-    /// and `&'2 i32` respectively.
-    ///
-    /// Once we to this method, we have completed region inference and want to
-    /// call `infer_opaque_definition_from_instantiation` to get the inferred
-    /// type of `_Return<'_x>`. `infer_opaque_definition_from_instantiation`
-    /// compares lifetimes directly, so we need to map the inference variables
-    /// back to concrete lifetimes: `'static`, `ReEarlyParam` or `ReLateParam`.
-    ///
-    /// First we map the regions in the generic parameters `_Return<'1>` to
-    /// their `external_name` giving `_Return<'a>`. This step is a bit involved.
-    /// See the [rustc-dev-guide chapter] for more info.
-    ///
-    /// Then we map all the lifetimes in the concrete type to an equal
-    /// universal region that occurs in the opaque type's args, in this case
-    /// this would result in `&'a i32`. We only consider regions in the args
-    /// in case there is an equal region that does not. For example, this should
-    /// be allowed:
-    /// `fn f<'a: 'b, 'b: 'a>(x: *mut &'b i32) -> impl Sized + 'a { x }`
-    ///
-    /// This will then allow `infer_opaque_definition_from_instantiation` to
-    /// determine that `_Return<'_x> = &'_x i32`.
-    ///
-    /// There's a slight complication around closures. Given
-    /// `fn f<'a: 'a>() { || {} }` the closure's type is something like
-    /// `f::<'a>::{{closure}}`. The region parameter from f is essentially
-    /// ignored by type checking so ends up being inferred to an empty region.
-    /// Calling `universal_upper_bound` for such a region gives `fr_fn_body`,
-    /// which has no `external_name` in which case we use `'{erased}` as the
-    /// region to pass to `infer_opaque_definition_from_instantiation`.
-    ///
-    /// [rustc-dev-guide chapter]:
-    /// https://rustc-dev-guide.rust-lang.org/opaque-types-region-infer-restrictions.html
-    #[instrument(level = "debug", skip(self, root_cx, infcx))]
-    pub(crate) fn infer_opaque_types(
-        &self,
-        root_cx: &mut BorrowCheckRootCtxt<'tcx>,
-        infcx: &InferCtxt<'tcx>,
-        opaque_ty_decls: FxIndexMap<OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>>,
-    ) -> Vec<DeferredOpaqueTypeError<'tcx>> {
-        let mut errors = Vec::new();
-        let mut decls_modulo_regions: FxIndexMap<OpaqueTypeKey<'tcx>, (OpaqueTypeKey<'tcx>, Span)> =
-            FxIndexMap::default();
-
-        for (opaque_type_key, concrete_type) in opaque_ty_decls {
-            debug!(?opaque_type_key, ?concrete_type);
-
-            let mut arg_regions: Vec<(ty::RegionVid, ty::Region<'_>)> =
-                vec![(self.universal_regions().fr_static, infcx.tcx.lifetimes.re_static)];
-
-            let opaque_type_key =
-                opaque_type_key.fold_captured_lifetime_args(infcx.tcx, |region| {
-                    // Use the SCC representative instead of directly using `region`.
-                    // See [rustc-dev-guide chapter] § "Strict lifetime equality".
-                    let scc = self.constraint_sccs.scc(region.as_var());
-                    let vid = self.scc_representative(scc);
-                    let named = match self.definitions[vid].origin {
-                        // Iterate over all universal regions in a consistent order and find the
-                        // *first* equal region. This makes sure that equal lifetimes will have
-                        // the same name and simplifies subsequent handling.
-                        // See [rustc-dev-guide chapter] § "Semantic lifetime equality".
-                        NllRegionVariableOrigin::FreeRegion => self
-                            .universal_regions()
-                            .universal_regions_iter()
-                            .filter(|&ur| {
-                                // See [rustc-dev-guide chapter] § "Closure restrictions".
-                                !matches!(
-                                    self.universal_regions().region_classification(ur),
-                                    Some(RegionClassification::External)
-                                )
-                            })
-                            .find(|&ur| self.universal_region_relations.equal(vid, ur))
-                            .map(|ur| self.definitions[ur].external_name.unwrap()),
-                        NllRegionVariableOrigin::Placeholder(placeholder) => {
-                            Some(ty::Region::new_placeholder(infcx.tcx, placeholder))
-                        }
-                        NllRegionVariableOrigin::Existential { .. } => None,
-                    }
-                    .unwrap_or_else(|| {
-                        ty::Region::new_error_with_message(
-                            infcx.tcx,
-                            concrete_type.span,
-                            "opaque type with non-universal region args",
-                        )
-                    });
-
-                    arg_regions.push((vid, named));
-                    named
-                });
-            debug!(?opaque_type_key, ?arg_regions);
-
-            let concrete_type = fold_regions(infcx.tcx, concrete_type, |region, _| {
-                arg_regions
-                    .iter()
-                    .find(|&&(arg_vid, _)| self.eval_equal(region.as_var(), arg_vid))
-                    .map(|&(_, arg_named)| arg_named)
-                    .unwrap_or(infcx.tcx.lifetimes.re_erased)
-            });
-            debug!(?concrete_type);
-
-            let ty = match infcx
-                .infer_opaque_definition_from_instantiation(opaque_type_key, concrete_type)
-            {
-                Ok(ty) => ty,
-                Err(err) => {
-                    errors.push(DeferredOpaqueTypeError::InvalidOpaqueTypeArgs(err));
-                    continue;
-                }
-            };
-
-            // Sometimes, when the hidden type is an inference variable, it can happen that
-            // the hidden type becomes the opaque type itself. In this case, this was an opaque
-            // usage of the opaque type and we can ignore it. This check is mirrored in typeck's
-            // writeback.
-            if !infcx.next_trait_solver() {
-                if let ty::Alias(ty::Opaque, alias_ty) = ty.kind()
-                    && alias_ty.def_id == opaque_type_key.def_id.to_def_id()
-                    && alias_ty.args == opaque_type_key.args
-                {
-                    continue;
-                }
-            }
-
-            root_cx.add_concrete_opaque_type(
-                opaque_type_key.def_id,
-                OpaqueHiddenType { span: concrete_type.span, ty },
-            );
-
-            // Check that all opaque types have the same region parameters if they have the same
-            // non-region parameters. This is necessary because within the new solver we perform
-            // various query operations modulo regions, and thus could unsoundly select some impls
-            // that don't hold.
-            if let Some((prev_decl_key, prev_span)) = decls_modulo_regions.insert(
-                infcx.tcx.erase_regions(opaque_type_key),
-                (opaque_type_key, concrete_type.span),
-            ) && let Some((arg1, arg2)) = std::iter::zip(
-                prev_decl_key.iter_captured_args(infcx.tcx).map(|(_, arg)| arg),
-                opaque_type_key.iter_captured_args(infcx.tcx).map(|(_, arg)| arg),
-            )
-            .find(|(arg1, arg2)| arg1 != arg2)
-            {
-                errors.push(DeferredOpaqueTypeError::LifetimeMismatchOpaqueParam(
-                    LifetimeMismatchOpaqueParam {
-                        arg: arg1,
-                        prev: arg2,
-                        span: prev_span,
-                        prev_span: concrete_type.span,
-                    },
-                ));
-            }
-        }
-
-        errors
-    }
-
-    /// Map the regions in the type to named regions. This is similar to what
-    /// `infer_opaque_types` does, but can infer any universal region, not only
-    /// ones from the args for the opaque type. It also doesn't double check
-    /// that the regions produced are in fact equal to the named region they are
-    /// replaced with. This is fine because this function is only to improve the
-    /// region names in error messages.
-    ///
-    /// This differs from `MirBorrowckCtxt::name_regions` since it is particularly
-    /// lax with mapping region vids that are *shorter* than a universal region to
-    /// that universal region. This is useful for member region constraints since
-    /// we want to suggest a universal region name to capture even if it's technically
-    /// not equal to the error region.
-    pub(crate) fn name_regions_for_member_constraint<T>(&self, tcx: TyCtxt<'tcx>, ty: T) -> T
-    where
-        T: TypeFoldable<TyCtxt<'tcx>>,
-    {
-        fold_regions(tcx, ty, |region, _| match region.kind() {
-            ty::ReVar(vid) => {
-                let scc = self.constraint_sccs.scc(vid);
-
-                // Special handling of higher-ranked regions.
-                if !self.max_nameable_universe(scc).is_root() {
-                    match self.scc_values.placeholders_contained_in(scc).enumerate().last() {
-                        // If the region contains a single placeholder then they're equal.
-                        Some((0, placeholder)) => {
-                            return ty::Region::new_placeholder(tcx, placeholder);
-                        }
-
-                        // Fallback: this will produce a cryptic error message.
-                        _ => return region,
-                    }
-                }
-
-                // Find something that we can name
-                let upper_bound = self.approx_universal_upper_bound(vid);
-                if let Some(universal_region) = self.definitions[upper_bound].external_name {
-                    return universal_region;
-                }
-
-                // Nothing exact found, so we pick a named upper bound, if there's only one.
-                // If there's >1 universal region, then we probably are dealing w/ an intersection
-                // region which cannot be mapped back to a universal.
-                // FIXME: We could probably compute the LUB if there is one.
-                let scc = self.constraint_sccs.scc(vid);
-                let upper_bounds: Vec<_> = self
-                    .reverse_scc_graph()
-                    .upper_bounds(scc)
-                    .filter_map(|vid| self.definitions[vid].external_name)
-                    .filter(|r| !r.is_static())
-                    .collect();
-                match &upper_bounds[..] {
-                    [universal_region] => *universal_region,
-                    _ => region,
-                }
-            }
-            _ => region,
-        })
-    }
-}
-
-#[extension(pub trait InferCtxtExt<'tcx>)]
-impl<'tcx> InferCtxt<'tcx> {
-    /// Given the fully resolved, instantiated type for an opaque
-    /// type, i.e., the value of an inference variable like C1 or C2
-    /// (*), computes the "definition type" for an opaque type
-    /// definition -- that is, the inferred value of `Foo1<'x>` or
-    /// `Foo2<'x>` that we would conceptually use in its definition:
-    /// ```ignore (illustrative)
-    /// type Foo1<'x> = impl Bar<'x> = AAA;  // <-- this type AAA
-    /// type Foo2<'x> = impl Bar<'x> = BBB;  // <-- or this type BBB
-    /// fn foo<'a, 'b>(..) -> (Foo1<'a>, Foo2<'b>) { .. }
-    /// ```
-    /// Note that these values are defined in terms of a distinct set of
-    /// generic parameters (`'x` instead of `'a`) from C1 or C2. The main
-    /// purpose of this function is to do that translation.
-    ///
-    /// (*) C1 and C2 were introduced in the comments on
-    /// `register_member_constraints`. Read that comment for more context.
-    ///
-    /// # Parameters
-    ///
-    /// - `def_id`, the `impl Trait` type
-    /// - `args`, the args used to instantiate this opaque type
-    /// - `instantiated_ty`, the inferred type C1 -- fully resolved, lifted version of
-    ///   `opaque_defn.concrete_ty`
-    #[instrument(level = "debug", skip(self))]
-    fn infer_opaque_definition_from_instantiation(
-        &self,
-        opaque_type_key: OpaqueTypeKey<'tcx>,
-        instantiated_ty: OpaqueHiddenType<'tcx>,
-    ) -> Result<Ty<'tcx>, InvalidOpaqueTypeArgs<'tcx>> {
-        check_opaque_type_parameter_valid(
-            self,
-            opaque_type_key,
-            instantiated_ty.span,
-            DefiningScopeKind::MirBorrowck,
-        )?;
-
-        let definition_ty = instantiated_ty
-            .remap_generic_params_to_declaration_params(
-                opaque_type_key,
-                self.tcx,
-                DefiningScopeKind::MirBorrowck,
-            )
-            .ty;
-
-        definition_ty.error_reported()?;
-        Ok(definition_ty)
-    }
-}
diff --git a/compiler/rustc_borrowck/src/region_infer/opaque_types/member_constraints.rs b/compiler/rustc_borrowck/src/region_infer/opaque_types/member_constraints.rs
new file mode 100644
index 00000000000..667fc440ac0
--- /dev/null
+++ b/compiler/rustc_borrowck/src/region_infer/opaque_types/member_constraints.rs
@@ -0,0 +1,194 @@
+use rustc_data_structures::fx::FxHashMap;
+use rustc_hir::def_id::DefId;
+use rustc_middle::bug;
+use rustc_middle::ty::{
+    self, GenericArgsRef, Region, RegionVid, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable,
+    TypeVisitor,
+};
+use tracing::{debug, instrument};
+
+use super::DefiningUse;
+use super::region_ctxt::RegionCtxt;
+use crate::constraints::ConstraintSccIndex;
+
+pub(super) fn apply_member_constraints<'tcx>(
+    rcx: &mut RegionCtxt<'_, 'tcx>,
+    defining_uses: &[DefiningUse<'tcx>],
+) {
+    // Start by collecting the member constraints of all defining uses.
+    //
+    // Applying member constraints can influence other member constraints,
+    // so we first collect and then apply them.
+    let mut member_constraints = Default::default();
+    for defining_use in defining_uses {
+        let mut visitor = CollectMemberConstraintsVisitor {
+            rcx,
+            defining_use,
+            member_constraints: &mut member_constraints,
+        };
+        defining_use.hidden_type.ty.visit_with(&mut visitor);
+    }
+
+    // Now walk over the region graph, visiting the smallest regions first and then all
+    // regions which have to outlive that one.
+    //
+    // Whenever we encounter a member region, we mutate the value of this SCC. This is
+    // as if we'd introduce new outlives constraints. However, we discard these region
+    // values after we've inferred the hidden types of opaques and apply the region
+    // constraints by simply equating the actual hidden type with the inferred one.
+    debug!(?member_constraints);
+    for scc_a in rcx.constraint_sccs.all_sccs() {
+        debug!(?scc_a);
+        // Start by  adding the region values required by outlives constraints. This
+        // matches how we compute the final region values in `fn compute_regions`.
+        //
+        // We need to do this here to get a lower bound when applying member constraints.
+        // This propagates the region values added by previous member constraints.
+        for &scc_b in rcx.constraint_sccs.successors(scc_a) {
+            debug!(?scc_b);
+            rcx.scc_values.add_region(scc_a, scc_b);
+        }
+
+        for defining_use in member_constraints.get(&scc_a).into_iter().flatten() {
+            apply_member_constraint(rcx, scc_a, &defining_use.arg_regions);
+        }
+    }
+}
+
+#[instrument(level = "debug", skip(rcx))]
+fn apply_member_constraint<'tcx>(
+    rcx: &mut RegionCtxt<'_, 'tcx>,
+    member: ConstraintSccIndex,
+    arg_regions: &[RegionVid],
+) {
+    // If the member region lives in a higher universe, we currently choose
+    // the most conservative option by leaving it unchanged.
+    if !rcx.max_placeholder_universe_reached(member).is_root() {
+        return;
+    }
+
+    // The existing value of `'member` is a lower-bound. If its is already larger than
+    // some universal region, we cannot equate it with that region. Said differently, we
+    // ignore choice regions which are smaller than this member region.
+    let mut choice_regions = arg_regions
+        .iter()
+        .copied()
+        .map(|r| rcx.representative(r).rvid())
+        .filter(|&choice_region| {
+            rcx.scc_values.universal_regions_outlived_by(member).all(|lower_bound| {
+                rcx.universal_region_relations.outlives(choice_region, lower_bound)
+            })
+        })
+        .collect::<Vec<_>>();
+    debug!(?choice_regions, "after enforcing lower-bound");
+
+    // Now find all the *upper bounds* -- that is, each UB is a
+    // free region that must outlive the member region `R0` (`UB:
+    // R0`). Therefore, we need only keep an option `O` if `UB: O`
+    // for all UB.
+    //
+    // If we have a requirement `'upper_bound: 'member`, equating `'member`
+    // with some region `'choice` means we now also require `'upper_bound: 'choice`.
+    // Avoid choice regions for which this does not hold.
+    for ub in rcx.rev_scc_graph.upper_bounds(member) {
+        choice_regions
+            .retain(|&choice_region| rcx.universal_region_relations.outlives(ub, choice_region));
+    }
+    debug!(?choice_regions, "after enforcing upper-bound");
+
+    // At this point we can pick any member of `choice_regions` and would like to choose
+    // it to be a small as possible. To avoid potential non-determinism we will pick the
+    // smallest such choice.
+    //
+    // Because universal regions are only partially ordered (i.e, not every two regions are
+    // comparable), we will ignore any region that doesn't compare to all others when picking
+    // the minimum choice.
+    //
+    // For example, consider `choice_regions = ['static, 'a, 'b, 'c, 'd, 'e]`, where
+    // `'static: 'a, 'static: 'b, 'a: 'c, 'b: 'c, 'c: 'd, 'c: 'e`.
+    // `['d, 'e]` are ignored because they do not compare - the same goes for `['a, 'b]`.
+    let totally_ordered_subset = choice_regions.iter().copied().filter(|&r1| {
+        choice_regions.iter().all(|&r2| {
+            rcx.universal_region_relations.outlives(r1, r2)
+                || rcx.universal_region_relations.outlives(r2, r1)
+        })
+    });
+    // Now we're left with `['static, 'c]`. Pick `'c` as the minimum!
+    let Some(min_choice) = totally_ordered_subset.reduce(|r1, r2| {
+        let r1_outlives_r2 = rcx.universal_region_relations.outlives(r1, r2);
+        let r2_outlives_r1 = rcx.universal_region_relations.outlives(r2, r1);
+        match (r1_outlives_r2, r2_outlives_r1) {
+            (true, true) => r1.min(r2),
+            (true, false) => r2,
+            (false, true) => r1,
+            (false, false) => bug!("incomparable regions in total order"),
+        }
+    }) else {
+        debug!("no unique minimum choice");
+        return;
+    };
+
+    debug!(?min_choice);
+    // Lift the member region to be at least as large as this `min_choice` by directly
+    // mutating the `scc_values` as we compute it. This acts as if we've added a
+    // `'member: 'min_choice` while not recomputing sccs. This means different sccs
+    // may now actually be equal.
+    let min_choice_scc = rcx.constraint_sccs.scc(min_choice);
+    rcx.scc_values.add_region(member, min_choice_scc);
+}
+
+struct CollectMemberConstraintsVisitor<'a, 'b, 'tcx> {
+    rcx: &'a RegionCtxt<'a, 'tcx>,
+    defining_use: &'b DefiningUse<'tcx>,
+    member_constraints: &'a mut FxHashMap<ConstraintSccIndex, Vec<&'b DefiningUse<'tcx>>>,
+}
+impl<'tcx> CollectMemberConstraintsVisitor<'_, '_, 'tcx> {
+    fn cx(&self) -> TyCtxt<'tcx> {
+        self.rcx.infcx.tcx
+    }
+    fn visit_closure_args(&mut self, def_id: DefId, args: GenericArgsRef<'tcx>) {
+        let generics = self.cx().generics_of(def_id);
+        for arg in args.iter().skip(generics.parent_count) {
+            arg.visit_with(self);
+        }
+    }
+}
+impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for CollectMemberConstraintsVisitor<'_, '_, 'tcx> {
+    fn visit_region(&mut self, r: Region<'tcx>) {
+        match r.kind() {
+            ty::ReBound(..) => return,
+            ty::ReVar(vid) => {
+                let scc = self.rcx.constraint_sccs.scc(vid);
+                self.member_constraints.entry(scc).or_default().push(self.defining_use);
+            }
+            _ => unreachable!(),
+        }
+    }
+
+    fn visit_ty(&mut self, ty: Ty<'tcx>) {
+        if !ty.flags().intersects(ty::TypeFlags::HAS_FREE_REGIONS) {
+            return;
+        }
+
+        match *ty.kind() {
+            ty::Closure(def_id, args)
+            | ty::CoroutineClosure(def_id, args)
+            | ty::Coroutine(def_id, args) => self.visit_closure_args(def_id, args),
+
+            ty::Alias(kind, ty::AliasTy { def_id, args, .. })
+                if let Some(variances) = self.cx().opt_alias_variances(kind, def_id) =>
+            {
+                // Skip lifetime parameters that are not captured, since they do
+                // not need member constraints registered for them; we'll erase
+                // them (and hopefully in the future replace them with placeholders).
+                for (&v, arg) in std::iter::zip(variances, args.iter()) {
+                    if v != ty::Bivariant {
+                        arg.visit_with(self)
+                    }
+                }
+            }
+
+            _ => ty.super_visit_with(self),
+        }
+    }
+}
diff --git a/compiler/rustc_borrowck/src/region_infer/opaque_types/mod.rs b/compiler/rustc_borrowck/src/region_infer/opaque_types/mod.rs
new file mode 100644
index 00000000000..bee82e17835
--- /dev/null
+++ b/compiler/rustc_borrowck/src/region_infer/opaque_types/mod.rs
@@ -0,0 +1,697 @@
+use std::iter;
+use std::rc::Rc;
+
+use rustc_data_structures::frozen::Frozen;
+use rustc_data_structures::fx::FxIndexMap;
+use rustc_hir::def_id::DefId;
+use rustc_infer::infer::outlives::env::RegionBoundPairs;
+use rustc_infer::infer::{InferCtxt, NllRegionVariableOrigin, OpaqueTypeStorageEntries};
+use rustc_infer::traits::ObligationCause;
+use rustc_macros::extension;
+use rustc_middle::mir::{Body, ConstraintCategory};
+use rustc_middle::ty::{
+    self, DefiningScopeKind, FallibleTypeFolder, GenericArg, GenericArgsRef, OpaqueHiddenType,
+    OpaqueTypeKey, Region, RegionVid, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable,
+    TypeVisitableExt, fold_regions,
+};
+use rustc_mir_dataflow::points::DenseLocationMap;
+use rustc_span::Span;
+use rustc_trait_selection::opaque_types::{
+    NonDefiningUseReason, opaque_type_has_defining_use_args,
+};
+use rustc_trait_selection::solve::NoSolution;
+use rustc_trait_selection::traits::query::type_op::custom::CustomTypeOp;
+use tracing::{debug, instrument};
+
+use super::reverse_sccs::ReverseSccGraph;
+use crate::consumers::RegionInferenceContext;
+use crate::session_diagnostics::LifetimeMismatchOpaqueParam;
+use crate::type_check::canonical::fully_perform_op_raw;
+use crate::type_check::free_region_relations::UniversalRegionRelations;
+use crate::type_check::{Locations, MirTypeckRegionConstraints};
+use crate::universal_regions::{RegionClassification, UniversalRegions};
+use crate::{BorrowCheckRootCtxt, BorrowckInferCtxt};
+
+mod member_constraints;
+mod region_ctxt;
+
+use member_constraints::apply_member_constraints;
+use region_ctxt::RegionCtxt;
+
+/// We defer errors from [fn handle_opaque_type_uses] and only report them
+/// if there are no `RegionErrors`. If there are region errors, it's likely
+/// that errors here are caused by them and don't need to be handled separately.
+pub(crate) enum DeferredOpaqueTypeError<'tcx> {
+    InvalidOpaqueTypeArgs(NonDefiningUseReason<'tcx>),
+    LifetimeMismatchOpaqueParam(LifetimeMismatchOpaqueParam<'tcx>),
+    UnexpectedHiddenRegion {
+        /// The opaque type.
+        opaque_type_key: OpaqueTypeKey<'tcx>,
+        /// The hidden type containing the member region.
+        hidden_type: OpaqueHiddenType<'tcx>,
+        /// The unexpected region.
+        member_region: Region<'tcx>,
+    },
+    NonDefiningUseInDefiningScope {
+        span: Span,
+        opaque_type_key: OpaqueTypeKey<'tcx>,
+    },
+}
+
+/// This looks at all uses of opaque types in their defining scope inside
+/// of this function.
+///
+/// It first uses all defining uses to compute the actual concrete type of each
+/// opaque type definition.
+///
+/// We then apply this inferred type to actually check all uses of the opaque.
+pub(crate) fn handle_opaque_type_uses<'tcx>(
+    root_cx: &mut BorrowCheckRootCtxt<'tcx>,
+    infcx: &BorrowckInferCtxt<'tcx>,
+    body: &Body<'tcx>,
+    universal_region_relations: &Frozen<UniversalRegionRelations<'tcx>>,
+    region_bound_pairs: &RegionBoundPairs<'tcx>,
+    known_type_outlives_obligations: &[ty::PolyTypeOutlivesPredicate<'tcx>],
+    location_map: &Rc<DenseLocationMap>,
+    constraints: &mut MirTypeckRegionConstraints<'tcx>,
+) -> Vec<DeferredOpaqueTypeError<'tcx>> {
+    let tcx = infcx.tcx;
+    let opaque_types = infcx.clone_opaque_types();
+    if opaque_types.is_empty() {
+        return Vec::new();
+    }
+
+    // We need to eagerly map all regions to NLL vars here, as we need to make sure we've
+    // introduced nll vars for all used placeholders.
+    //
+    // We need to resolve inference vars as even though we're in MIR typeck, we may still
+    // encounter inference variables, e.g. when checking user types.
+    let opaque_types_storage_num_entries = infcx.inner.borrow_mut().opaque_types().num_entries();
+    let opaque_types = opaque_types
+        .into_iter()
+        .map(|entry| {
+            fold_regions(tcx, infcx.resolve_vars_if_possible(entry), |r, _| {
+                let vid = if let ty::RePlaceholder(placeholder) = r.kind() {
+                    constraints.placeholder_region(infcx, placeholder).as_var()
+                } else {
+                    universal_region_relations.universal_regions.to_region_vid(r)
+                };
+                Region::new_var(tcx, vid)
+            })
+        })
+        .collect::<Vec<_>>();
+
+    debug!(?opaque_types);
+
+    let errors = compute_concrete_opaque_types(
+        root_cx,
+        infcx,
+        constraints,
+        universal_region_relations,
+        Rc::clone(location_map),
+        &opaque_types,
+    );
+
+    if !errors.is_empty() {
+        return errors;
+    }
+
+    let errors = apply_computed_concrete_opaque_types(
+        root_cx,
+        infcx,
+        body,
+        &universal_region_relations.universal_regions,
+        region_bound_pairs,
+        known_type_outlives_obligations,
+        constraints,
+        &opaque_types,
+    );
+
+    detect_opaque_types_added_while_handling_opaque_types(infcx, opaque_types_storage_num_entries);
+
+    errors
+}
+
+/// Maps an NLL var to a deterministically chosen equal universal region.
+///
+/// See the corresponding [rustc-dev-guide chapter] for more details. This
+/// ignores changes to the region values due to member constraints. Applying
+/// member constraints does not impact the result of this function.
+///
+/// [rustc-dev-guide chapter]: https://rustc-dev-guide.rust-lang.org/borrow_check/opaque-types-region-inference-restrictions.html
+fn nll_var_to_universal_region<'tcx>(
+    rcx: &RegionCtxt<'_, 'tcx>,
+    r: RegionVid,
+) -> Option<Region<'tcx>> {
+    // Use the SCC representative instead of directly using `region`.
+    // See [rustc-dev-guide chapter] § "Strict lifetime equality".
+    let vid = rcx.representative(r).rvid();
+    match rcx.definitions[vid].origin {
+        // Iterate over all universal regions in a consistent order and find the
+        // *first* equal region. This makes sure that equal lifetimes will have
+        // the same name and simplifies subsequent handling.
+        // See [rustc-dev-guide chapter] § "Semantic lifetime equality".
+        NllRegionVariableOrigin::FreeRegion => rcx
+            .universal_regions()
+            .universal_regions_iter()
+            .filter(|&ur| {
+                // See [rustc-dev-guide chapter] § "Closure restrictions".
+                !matches!(
+                    rcx.universal_regions().region_classification(ur),
+                    Some(RegionClassification::External)
+                )
+            })
+            .find(|&ur| rcx.universal_region_relations.equal(vid, ur))
+            .map(|ur| rcx.definitions[ur].external_name.unwrap()),
+        NllRegionVariableOrigin::Placeholder(placeholder) => {
+            Some(ty::Region::new_placeholder(rcx.infcx.tcx, placeholder))
+        }
+        // If `r` were equal to any universal region, its SCC representative
+        // would have been set to a free region.
+        NllRegionVariableOrigin::Existential { .. } => None,
+    }
+}
+
+#[derive(Debug)]
+struct DefiningUse<'tcx> {
+    /// The opaque type using non NLL vars. This uses the actual
+    /// free regions and placeholders. This is necessary
+    /// to interact with code outside of `rustc_borrowck`.
+    opaque_type_key: OpaqueTypeKey<'tcx>,
+    arg_regions: Vec<RegionVid>,
+    hidden_type: OpaqueHiddenType<'tcx>,
+}
+
+/// This computes the actual hidden types of the opaque types and maps them to their
+/// definition sites. Outside of registering the computed concrete types this function
+/// does not mutate the current borrowck state.
+///
+/// While it may fail to infer the hidden type and return errors, we always apply
+/// the computed concrete hidden type to all opaque type uses to check whether they
+/// are correct. This is necessary to support non-defining uses of opaques in their
+/// defining scope.
+///
+/// It also means that this whole function is not really soundness critical as we
+/// recheck all uses of the opaques regardless.
+fn compute_concrete_opaque_types<'tcx>(
+    root_cx: &mut BorrowCheckRootCtxt<'tcx>,
+    infcx: &BorrowckInferCtxt<'tcx>,
+    constraints: &MirTypeckRegionConstraints<'tcx>,
+    universal_region_relations: &Frozen<UniversalRegionRelations<'tcx>>,
+    location_map: Rc<DenseLocationMap>,
+    opaque_types: &[(OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>)],
+) -> Vec<DeferredOpaqueTypeError<'tcx>> {
+    let mut errors = Vec::new();
+    // When computing the hidden type we need to track member constraints.
+    // We don't mutate the region graph used by `fn compute_regions` but instead
+    // manually track region information via a `RegionCtxt`. We discard this
+    // information at the end of this function.
+    let mut rcx = RegionCtxt::new(infcx, universal_region_relations, location_map, constraints);
+
+    // We start by checking each use of an opaque type during type check and
+    // check whether the generic arguments of the opaque type are fully
+    // universal, if so, it's a defining use.
+    let defining_uses = collect_defining_uses(root_cx, &mut rcx, opaque_types, &mut errors);
+
+    // We now compute and apply member constraints for all regions in the hidden
+    // types of each defining use. This mutates the region values of the `rcx` which
+    // is used when mapping the defining uses to the definition site.
+    apply_member_constraints(&mut rcx, &defining_uses);
+
+    // After applying member constraints, we now check whether all member regions ended
+    // up equal to one of their choice regions and compute the actual concrete type of
+    // the opaque type definition. This is stored in the `root_cx`.
+    compute_concrete_types_from_defining_uses(root_cx, &rcx, &defining_uses, &mut errors);
+    errors
+}
+
+#[instrument(level = "debug", skip_all, ret)]
+fn collect_defining_uses<'tcx>(
+    root_cx: &mut BorrowCheckRootCtxt<'tcx>,
+    rcx: &mut RegionCtxt<'_, 'tcx>,
+    opaque_types: &[(OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>)],
+    errors: &mut Vec<DeferredOpaqueTypeError<'tcx>>,
+) -> Vec<DefiningUse<'tcx>> {
+    let infcx = rcx.infcx;
+    let mut defining_uses = vec![];
+    for &(opaque_type_key, hidden_type) in opaque_types {
+        let non_nll_opaque_type_key = opaque_type_key.fold_captured_lifetime_args(infcx.tcx, |r| {
+            nll_var_to_universal_region(&rcx, r.as_var()).unwrap_or(r)
+        });
+        if let Err(err) = opaque_type_has_defining_use_args(
+            infcx,
+            non_nll_opaque_type_key,
+            hidden_type.span,
+            DefiningScopeKind::MirBorrowck,
+        ) {
+            // A non-defining use. This is a hard error on stable and gets ignored
+            // with `TypingMode::Borrowck`.
+            if infcx.tcx.use_typing_mode_borrowck() {
+                match err {
+                    NonDefiningUseReason::Tainted(guar) => root_cx.add_concrete_opaque_type(
+                        opaque_type_key.def_id,
+                        OpaqueHiddenType::new_error(infcx.tcx, guar),
+                    ),
+                    _ => debug!(?non_nll_opaque_type_key, ?err, "ignoring non-defining use"),
+                }
+            } else {
+                errors.push(DeferredOpaqueTypeError::InvalidOpaqueTypeArgs(err));
+            }
+            continue;
+        }
+
+        // We use the original `opaque_type_key` to compute the `arg_regions`.
+        let arg_regions = iter::once(rcx.universal_regions().fr_static)
+            .chain(
+                opaque_type_key
+                    .iter_captured_args(infcx.tcx)
+                    .filter_map(|(_, arg)| arg.as_region())
+                    .map(Region::as_var),
+            )
+            .collect();
+        defining_uses.push(DefiningUse {
+            opaque_type_key: non_nll_opaque_type_key,
+            arg_regions,
+            hidden_type,
+        });
+    }
+
+    defining_uses
+}
+
+fn compute_concrete_types_from_defining_uses<'tcx>(
+    root_cx: &mut BorrowCheckRootCtxt<'tcx>,
+    rcx: &RegionCtxt<'_, 'tcx>,
+    defining_uses: &[DefiningUse<'tcx>],
+    errors: &mut Vec<DeferredOpaqueTypeError<'tcx>>,
+) {
+    let infcx = rcx.infcx;
+    let tcx = infcx.tcx;
+    let mut decls_modulo_regions: FxIndexMap<OpaqueTypeKey<'tcx>, (OpaqueTypeKey<'tcx>, Span)> =
+        FxIndexMap::default();
+    for &DefiningUse { opaque_type_key, ref arg_regions, hidden_type } in defining_uses {
+        // After applying member constraints, we now map all regions in the hidden type
+        // to the `arg_regions` of this defining use. In case a region in the hidden type
+        // ended up not being equal to any such region, we error.
+        let hidden_type =
+            match hidden_type.try_fold_with(&mut ToArgRegionsFolder::new(rcx, arg_regions)) {
+                Ok(hidden_type) => hidden_type,
+                Err(r) => {
+                    errors.push(DeferredOpaqueTypeError::UnexpectedHiddenRegion {
+                        hidden_type,
+                        opaque_type_key,
+                        member_region: ty::Region::new_var(tcx, r),
+                    });
+                    let guar = tcx.dcx().span_delayed_bug(
+                        hidden_type.span,
+                        "opaque type with non-universal region args",
+                    );
+                    ty::OpaqueHiddenType::new_error(tcx, guar)
+                }
+            };
+
+        // Now that we mapped the member regions to their final value,
+        // map the arguments of the opaque type key back to the parameters
+        // of the opaque type definition.
+        let ty = infcx
+            .infer_opaque_definition_from_instantiation(opaque_type_key, hidden_type)
+            .unwrap_or_else(|_| {
+                Ty::new_error_with_message(
+                    rcx.infcx.tcx,
+                    hidden_type.span,
+                    "deferred invalid opaque type args",
+                )
+            });
+
+        // Sometimes, when the hidden type is an inference variable, it can happen that
+        // the hidden type becomes the opaque type itself. In this case, this was an opaque
+        // usage of the opaque type and we can ignore it. This check is mirrored in typeck's
+        // writeback.
+        if !rcx.infcx.tcx.use_typing_mode_borrowck() {
+            if let ty::Alias(ty::Opaque, alias_ty) = ty.kind()
+                && alias_ty.def_id == opaque_type_key.def_id.to_def_id()
+                && alias_ty.args == opaque_type_key.args
+            {
+                continue;
+            }
+        }
+
+        // Check that all opaque types have the same region parameters if they have the same
+        // non-region parameters. This is necessary because within the new solver we perform
+        // various query operations modulo regions, and thus could unsoundly select some impls
+        // that don't hold.
+        //
+        // FIXME(-Znext-solver): This isn't necessary after all. We can remove this check again.
+        if let Some((prev_decl_key, prev_span)) = decls_modulo_regions.insert(
+            rcx.infcx.tcx.erase_regions(opaque_type_key),
+            (opaque_type_key, hidden_type.span),
+        ) && let Some((arg1, arg2)) = std::iter::zip(
+            prev_decl_key.iter_captured_args(infcx.tcx).map(|(_, arg)| arg),
+            opaque_type_key.iter_captured_args(infcx.tcx).map(|(_, arg)| arg),
+        )
+        .find(|(arg1, arg2)| arg1 != arg2)
+        {
+            errors.push(DeferredOpaqueTypeError::LifetimeMismatchOpaqueParam(
+                LifetimeMismatchOpaqueParam {
+                    arg: arg1,
+                    prev: arg2,
+                    span: prev_span,
+                    prev_span: hidden_type.span,
+                },
+            ));
+        }
+        root_cx.add_concrete_opaque_type(
+            opaque_type_key.def_id,
+            OpaqueHiddenType { span: hidden_type.span, ty },
+        );
+    }
+}
+
+/// A folder to map the regions in the hidden type to their corresponding `arg_regions`.
+///
+/// This folder has to differentiate between member regions and other regions in the hidden
+/// type. Member regions have to be equal to one of the `arg_regions` while other regions simply
+/// get treated as an existential region in the opaque if they are not. Existential
+/// regions are currently represented using `'erased`.
+struct ToArgRegionsFolder<'a, 'tcx> {
+    rcx: &'a RegionCtxt<'a, 'tcx>,
+    // When folding closure args or bivariant alias arguments, we simply
+    // ignore non-member regions. However, we still need to map member
+    // regions to their arg region even if its in a closure argument.
+    //
+    // See tests/ui/type-alias-impl-trait/closure_wf_outlives.rs for an example.
+    erase_unknown_regions: bool,
+    arg_regions: &'a [RegionVid],
+}
+
+impl<'a, 'tcx> ToArgRegionsFolder<'a, 'tcx> {
+    fn new(
+        rcx: &'a RegionCtxt<'a, 'tcx>,
+        arg_regions: &'a [RegionVid],
+    ) -> ToArgRegionsFolder<'a, 'tcx> {
+        ToArgRegionsFolder { rcx, erase_unknown_regions: false, arg_regions }
+    }
+
+    fn fold_non_member_arg(&mut self, arg: GenericArg<'tcx>) -> GenericArg<'tcx> {
+        let prev = self.erase_unknown_regions;
+        self.erase_unknown_regions = true;
+        let res = arg.try_fold_with(self).unwrap();
+        self.erase_unknown_regions = prev;
+        res
+    }
+
+    fn fold_closure_args(
+        &mut self,
+        def_id: DefId,
+        args: GenericArgsRef<'tcx>,
+    ) -> Result<GenericArgsRef<'tcx>, RegionVid> {
+        let generics = self.cx().generics_of(def_id);
+        self.cx().mk_args_from_iter(args.iter().enumerate().map(|(index, arg)| {
+            if index < generics.parent_count {
+                Ok(self.fold_non_member_arg(arg))
+            } else {
+                arg.try_fold_with(self)
+            }
+        }))
+    }
+}
+impl<'tcx> FallibleTypeFolder<TyCtxt<'tcx>> for ToArgRegionsFolder<'_, 'tcx> {
+    type Error = RegionVid;
+    fn cx(&self) -> TyCtxt<'tcx> {
+        self.rcx.infcx.tcx
+    }
+
+    fn try_fold_region(&mut self, r: Region<'tcx>) -> Result<Region<'tcx>, RegionVid> {
+        match r.kind() {
+            // ignore bound regions, keep visiting
+            ty::ReBound(_, _) => Ok(r),
+            _ => {
+                let r = r.as_var();
+                if let Some(arg_region) = self
+                    .arg_regions
+                    .iter()
+                    .copied()
+                    .find(|&arg_vid| self.rcx.eval_equal(r, arg_vid))
+                    .and_then(|r| nll_var_to_universal_region(self.rcx, r))
+                {
+                    Ok(arg_region)
+                } else if self.erase_unknown_regions {
+                    Ok(self.cx().lifetimes.re_erased)
+                } else {
+                    Err(r)
+                }
+            }
+        }
+    }
+
+    fn try_fold_ty(&mut self, ty: Ty<'tcx>) -> Result<Ty<'tcx>, RegionVid> {
+        if !ty.flags().intersects(ty::TypeFlags::HAS_FREE_REGIONS) {
+            return Ok(ty);
+        }
+
+        let tcx = self.cx();
+        Ok(match *ty.kind() {
+            ty::Closure(def_id, args) => {
+                Ty::new_closure(tcx, def_id, self.fold_closure_args(def_id, args)?)
+            }
+
+            ty::CoroutineClosure(def_id, args) => {
+                Ty::new_coroutine_closure(tcx, def_id, self.fold_closure_args(def_id, args)?)
+            }
+
+            ty::Coroutine(def_id, args) => {
+                Ty::new_coroutine(tcx, def_id, self.fold_closure_args(def_id, args)?)
+            }
+
+            ty::Alias(kind, ty::AliasTy { def_id, args, .. })
+                if let Some(variances) = tcx.opt_alias_variances(kind, def_id) =>
+            {
+                let args = tcx.mk_args_from_iter(std::iter::zip(variances, args.iter()).map(
+                    |(&v, s)| {
+                        if v == ty::Bivariant {
+                            Ok(self.fold_non_member_arg(s))
+                        } else {
+                            s.try_fold_with(self)
+                        }
+                    },
+                ))?;
+                ty::AliasTy::new_from_args(tcx, def_id, args).to_ty(tcx)
+            }
+
+            _ => ty.try_super_fold_with(self)?,
+        })
+    }
+}
+
+/// This function is what actually applies member constraints to the borrowck
+/// state. It is also responsible to check all uses of the opaques in their
+/// defining scope.
+///
+/// It does this by equating the hidden type of each use with the instantiated final
+/// hidden type of the opaque.
+fn apply_computed_concrete_opaque_types<'tcx>(
+    root_cx: &mut BorrowCheckRootCtxt<'tcx>,
+    infcx: &BorrowckInferCtxt<'tcx>,
+    body: &Body<'tcx>,
+    universal_regions: &UniversalRegions<'tcx>,
+    region_bound_pairs: &RegionBoundPairs<'tcx>,
+    known_type_outlives_obligations: &[ty::PolyTypeOutlivesPredicate<'tcx>],
+    constraints: &mut MirTypeckRegionConstraints<'tcx>,
+    opaque_types: &[(OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>)],
+) -> Vec<DeferredOpaqueTypeError<'tcx>> {
+    let tcx = infcx.tcx;
+    let mut errors = Vec::new();
+    for &(key, hidden_type) in opaque_types {
+        let Some(expected) = root_cx.get_concrete_opaque_type(key.def_id) else {
+            assert!(tcx.use_typing_mode_borrowck(), "non-defining use in defining scope");
+            errors.push(DeferredOpaqueTypeError::NonDefiningUseInDefiningScope {
+                span: hidden_type.span,
+                opaque_type_key: key,
+            });
+            let guar = tcx.dcx().span_delayed_bug(
+                hidden_type.span,
+                "non-defining use in the defining scope with no defining uses",
+            );
+            root_cx.add_concrete_opaque_type(key.def_id, OpaqueHiddenType::new_error(tcx, guar));
+            continue;
+        };
+
+        // We erase all non-member region of the opaque and need to treat these as existentials.
+        let expected = ty::fold_regions(tcx, expected.instantiate(tcx, key.args), |re, _dbi| {
+            match re.kind() {
+                ty::ReErased => infcx.next_nll_region_var(
+                    NllRegionVariableOrigin::Existential { name: None },
+                    || crate::RegionCtxt::Existential(None),
+                ),
+                _ => re,
+            }
+        });
+
+        // We now simply equate the expected with the actual hidden type.
+        let locations = Locations::All(hidden_type.span);
+        if let Err(guar) = fully_perform_op_raw(
+            infcx,
+            body,
+            universal_regions,
+            region_bound_pairs,
+            known_type_outlives_obligations,
+            constraints,
+            locations,
+            ConstraintCategory::OpaqueType,
+            CustomTypeOp::new(
+                |ocx| {
+                    let cause = ObligationCause::misc(
+                        hidden_type.span,
+                        body.source.def_id().expect_local(),
+                    );
+                    // We need to normalize both types in the old solver before equatingt them.
+                    let actual_ty = ocx.normalize(&cause, infcx.param_env, hidden_type.ty);
+                    let expected_ty = ocx.normalize(&cause, infcx.param_env, expected.ty);
+                    ocx.eq(&cause, infcx.param_env, actual_ty, expected_ty).map_err(|_| NoSolution)
+                },
+                "equating opaque types",
+            ),
+        ) {
+            root_cx.add_concrete_opaque_type(key.def_id, OpaqueHiddenType::new_error(tcx, guar));
+        }
+    }
+    errors
+}
+
+/// In theory `apply_concrete_opaque_types` could introduce new uses of opaque types.
+/// We do not check these new uses so this could be unsound.
+///
+/// We detect any new uses and simply delay a bug if they occur. If this results in
+/// an ICE we can properly handle this, but we haven't encountered any such test yet.
+///
+/// See the related comment in `FnCtxt::detect_opaque_types_added_during_writeback`.
+fn detect_opaque_types_added_while_handling_opaque_types<'tcx>(
+    infcx: &InferCtxt<'tcx>,
+    opaque_types_storage_num_entries: OpaqueTypeStorageEntries,
+) {
+    for (key, hidden_type) in infcx
+        .inner
+        .borrow_mut()
+        .opaque_types()
+        .opaque_types_added_since(opaque_types_storage_num_entries)
+    {
+        let opaque_type_string = infcx.tcx.def_path_str(key.def_id);
+        let msg = format!("unexpected cyclic definition of `{opaque_type_string}`");
+        infcx.dcx().span_delayed_bug(hidden_type.span, msg);
+    }
+
+    let _ = infcx.take_opaque_types();
+}
+
+impl<'tcx> RegionInferenceContext<'tcx> {
+    /// Map the regions in the type to named regions. This is similar to what
+    /// `infer_opaque_types` does, but can infer any universal region, not only
+    /// ones from the args for the opaque type. It also doesn't double check
+    /// that the regions produced are in fact equal to the named region they are
+    /// replaced with. This is fine because this function is only to improve the
+    /// region names in error messages.
+    ///
+    /// This differs from `MirBorrowckCtxt::name_regions` since it is particularly
+    /// lax with mapping region vids that are *shorter* than a universal region to
+    /// that universal region. This is useful for member region constraints since
+    /// we want to suggest a universal region name to capture even if it's technically
+    /// not equal to the error region.
+    pub(crate) fn name_regions_for_member_constraint<T>(&self, tcx: TyCtxt<'tcx>, ty: T) -> T
+    where
+        T: TypeFoldable<TyCtxt<'tcx>>,
+    {
+        fold_regions(tcx, ty, |region, _| match region.kind() {
+            ty::ReVar(vid) => {
+                let scc = self.constraint_sccs.scc(vid);
+
+                // Special handling of higher-ranked regions.
+                if !self.max_nameable_universe(scc).is_root() {
+                    match self.scc_values.placeholders_contained_in(scc).enumerate().last() {
+                        // If the region contains a single placeholder then they're equal.
+                        Some((0, placeholder)) => {
+                            return ty::Region::new_placeholder(tcx, placeholder);
+                        }
+
+                        // Fallback: this will produce a cryptic error message.
+                        _ => return region,
+                    }
+                }
+
+                // Find something that we can name
+                let upper_bound = self.approx_universal_upper_bound(vid);
+                if let Some(universal_region) = self.definitions[upper_bound].external_name {
+                    return universal_region;
+                }
+
+                // Nothing exact found, so we pick a named upper bound, if there's only one.
+                // If there's >1 universal region, then we probably are dealing w/ an intersection
+                // region which cannot be mapped back to a universal.
+                // FIXME: We could probably compute the LUB if there is one.
+                let scc = self.constraint_sccs.scc(vid);
+                let rev_scc_graph =
+                    ReverseSccGraph::compute(&self.constraint_sccs, self.universal_regions());
+                let upper_bounds: Vec<_> = rev_scc_graph
+                    .upper_bounds(scc)
+                    .filter_map(|vid| self.definitions[vid].external_name)
+                    .filter(|r| !r.is_static())
+                    .collect();
+                match &upper_bounds[..] {
+                    [universal_region] => *universal_region,
+                    _ => region,
+                }
+            }
+            _ => region,
+        })
+    }
+}
+
+#[extension(pub trait InferCtxtExt<'tcx>)]
+impl<'tcx> InferCtxt<'tcx> {
+    /// Given the fully resolved, instantiated type for an opaque
+    /// type, i.e., the value of an inference variable like C1 or C2
+    /// (*), computes the "definition type" for an opaque type
+    /// definition -- that is, the inferred value of `Foo1<'x>` or
+    /// `Foo2<'x>` that we would conceptually use in its definition:
+    /// ```ignore (illustrative)
+    /// type Foo1<'x> = impl Bar<'x> = AAA;  // <-- this type AAA
+    /// type Foo2<'x> = impl Bar<'x> = BBB;  // <-- or this type BBB
+    /// fn foo<'a, 'b>(..) -> (Foo1<'a>, Foo2<'b>) { .. }
+    /// ```
+    /// Note that these values are defined in terms of a distinct set of
+    /// generic parameters (`'x` instead of `'a`) from C1 or C2. The main
+    /// purpose of this function is to do that translation.
+    ///
+    /// (*) C1 and C2 were introduced in the comments on
+    /// `register_member_constraints`. Read that comment for more context.
+    ///
+    /// # Parameters
+    ///
+    /// - `def_id`, the `impl Trait` type
+    /// - `args`, the args used to instantiate this opaque type
+    /// - `instantiated_ty`, the inferred type C1 -- fully resolved, lifted version of
+    ///   `opaque_defn.concrete_ty`
+    #[instrument(level = "debug", skip(self))]
+    fn infer_opaque_definition_from_instantiation(
+        &self,
+        opaque_type_key: OpaqueTypeKey<'tcx>,
+        instantiated_ty: OpaqueHiddenType<'tcx>,
+    ) -> Result<Ty<'tcx>, NonDefiningUseReason<'tcx>> {
+        opaque_type_has_defining_use_args(
+            self,
+            opaque_type_key,
+            instantiated_ty.span,
+            DefiningScopeKind::MirBorrowck,
+        )?;
+
+        let definition_ty = instantiated_ty
+            .remap_generic_params_to_declaration_params(
+                opaque_type_key,
+                self.tcx,
+                DefiningScopeKind::MirBorrowck,
+            )
+            .ty;
+
+        definition_ty.error_reported()?;
+        Ok(definition_ty)
+    }
+}
diff --git a/compiler/rustc_borrowck/src/region_infer/opaque_types/region_ctxt.rs b/compiler/rustc_borrowck/src/region_infer/opaque_types/region_ctxt.rs
new file mode 100644
index 00000000000..88326e4eebf
--- /dev/null
+++ b/compiler/rustc_borrowck/src/region_infer/opaque_types/region_ctxt.rs
@@ -0,0 +1,114 @@
+use std::rc::Rc;
+
+use rustc_data_structures::frozen::Frozen;
+use rustc_index::IndexVec;
+use rustc_infer::infer::NllRegionVariableOrigin;
+use rustc_middle::ty::{RegionVid, UniverseIndex};
+use rustc_mir_dataflow::points::DenseLocationMap;
+
+use crate::BorrowckInferCtxt;
+use crate::constraints::ConstraintSccIndex;
+use crate::handle_placeholders::{SccAnnotations, region_definitions};
+use crate::region_infer::reverse_sccs::ReverseSccGraph;
+use crate::region_infer::values::RegionValues;
+use crate::region_infer::{ConstraintSccs, RegionDefinition, RegionTracker, Representative};
+use crate::type_check::MirTypeckRegionConstraints;
+use crate::type_check::free_region_relations::UniversalRegionRelations;
+use crate::universal_regions::UniversalRegions;
+
+/// A slimmed down version of [crate::region_infer::RegionInferenceContext] used
+/// only by opaque type handling.
+pub(super) struct RegionCtxt<'a, 'tcx> {
+    pub(super) infcx: &'a BorrowckInferCtxt<'tcx>,
+    pub(super) definitions: Frozen<IndexVec<RegionVid, RegionDefinition<'tcx>>>,
+    pub(super) universal_region_relations: &'a UniversalRegionRelations<'tcx>,
+    pub(super) constraint_sccs: ConstraintSccs,
+    pub(super) scc_annotations: IndexVec<ConstraintSccIndex, RegionTracker>,
+    pub(super) rev_scc_graph: ReverseSccGraph,
+    pub(super) scc_values: RegionValues<ConstraintSccIndex>,
+}
+
+impl<'a, 'tcx> RegionCtxt<'a, 'tcx> {
+    /// Creates a new `RegionCtxt` used to compute defining opaque type uses.
+    ///
+    /// This does not yet propagate region values. This is instead done lazily
+    /// when applying member constraints.
+    pub(super) fn new(
+        infcx: &'a BorrowckInferCtxt<'tcx>,
+        universal_region_relations: &'a Frozen<UniversalRegionRelations<'tcx>>,
+        location_map: Rc<DenseLocationMap>,
+        constraints: &MirTypeckRegionConstraints<'tcx>,
+    ) -> RegionCtxt<'a, 'tcx> {
+        let universal_regions = &universal_region_relations.universal_regions;
+        let (definitions, _has_placeholders) = region_definitions(infcx, universal_regions);
+        let mut scc_annotations = SccAnnotations::init(&definitions);
+        let constraint_sccs = ConstraintSccs::new_with_annotation(
+            &constraints
+                .outlives_constraints
+                .graph(definitions.len())
+                .region_graph(&constraints.outlives_constraints, universal_regions.fr_static),
+            &mut scc_annotations,
+        );
+        let scc_annotations = scc_annotations.scc_to_annotation;
+
+        // Unlike the `RegionInferenceContext`, we only care about free regions
+        // and fully ignore liveness and placeholders.
+        let placeholder_indices = Default::default();
+        let mut scc_values =
+            RegionValues::new(location_map, universal_regions.len(), placeholder_indices);
+        for variable in definitions.indices() {
+            let scc = constraint_sccs.scc(variable);
+            match definitions[variable].origin {
+                NllRegionVariableOrigin::FreeRegion => {
+                    scc_values.add_element(scc, variable);
+                }
+                _ => {}
+            }
+        }
+
+        let rev_scc_graph = ReverseSccGraph::compute(&constraint_sccs, universal_regions);
+        RegionCtxt {
+            infcx,
+            definitions,
+            universal_region_relations,
+            constraint_sccs,
+            scc_annotations,
+            rev_scc_graph,
+            scc_values,
+        }
+    }
+
+    pub(super) fn representative(&self, vid: RegionVid) -> Representative {
+        let scc = self.constraint_sccs.scc(vid);
+        self.scc_annotations[scc].representative
+    }
+
+    pub(crate) fn max_placeholder_universe_reached(
+        &self,
+        scc: ConstraintSccIndex,
+    ) -> UniverseIndex {
+        self.scc_annotations[scc].max_placeholder_universe_reached()
+    }
+
+    pub(super) fn universal_regions(&self) -> &UniversalRegions<'tcx> {
+        &self.universal_region_relations.universal_regions
+    }
+
+    pub(super) fn eval_equal(&self, r1_vid: RegionVid, r2_vid: RegionVid) -> bool {
+        let r1 = self.constraint_sccs.scc(r1_vid);
+        let r2 = self.constraint_sccs.scc(r2_vid);
+
+        if r1 == r2 {
+            return true;
+        }
+
+        let universal_outlives = |sub, sup| {
+            self.scc_values.universal_regions_outlived_by(sub).all(|r1| {
+                self.scc_values
+                    .universal_regions_outlived_by(sup)
+                    .any(|r2| self.universal_region_relations.outlives(r2, r1))
+            })
+        };
+        universal_outlives(r1, r2) && universal_outlives(r2, r1)
+    }
+}
diff --git a/compiler/rustc_borrowck/src/region_infer/reverse_sccs.rs b/compiler/rustc_borrowck/src/region_infer/reverse_sccs.rs
index 604265f8940..e8da85eccef 100644
--- a/compiler/rustc_borrowck/src/region_infer/reverse_sccs.rs
+++ b/compiler/rustc_borrowck/src/region_infer/reverse_sccs.rs
@@ -5,7 +5,6 @@ use rustc_data_structures::graph;
 use rustc_data_structures::graph::vec_graph::VecGraph;
 use rustc_middle::ty::RegionVid;
 
-use crate::RegionInferenceContext;
 use crate::constraints::ConstraintSccIndex;
 use crate::region_infer::ConstraintSccs;
 use crate::universal_regions::UniversalRegions;
@@ -57,12 +56,3 @@ impl ReverseSccGraph {
             .filter(move |r| duplicates.insert(*r))
     }
 }
-
-impl RegionInferenceContext<'_> {
-    /// Return the reverse graph of the region SCCs, initialising it if needed.
-    pub(super) fn reverse_scc_graph(&self) -> &ReverseSccGraph {
-        self.rev_scc_graph.get_or_init(|| {
-            ReverseSccGraph::compute(&self.constraint_sccs, self.universal_regions())
-        })
-    }
-}
diff --git a/compiler/rustc_borrowck/src/root_cx.rs b/compiler/rustc_borrowck/src/root_cx.rs
index 9b1d12aede5..4e90ae391bb 100644
--- a/compiler/rustc_borrowck/src/root_cx.rs
+++ b/compiler/rustc_borrowck/src/root_cx.rs
@@ -2,7 +2,7 @@ use rustc_abi::FieldIdx;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::def_id::LocalDefId;
 use rustc_middle::bug;
-use rustc_middle::ty::{OpaqueHiddenType, Ty, TyCtxt, TypeVisitableExt};
+use rustc_middle::ty::{EarlyBinder, OpaqueHiddenType, Ty, TyCtxt, TypeVisitableExt};
 use rustc_span::ErrorGuaranteed;
 use smallvec::SmallVec;
 
@@ -19,7 +19,7 @@ pub(super) struct BorrowCheckRootCtxt<'tcx> {
     tainted_by_errors: Option<ErrorGuaranteed>,
     /// This should be `None` during normal compilation. See [`crate::consumers`] for more
     /// information on how this is used.
-    pub(crate) consumer: Option<BorrowckConsumer<'tcx>>,
+    pub consumer: Option<BorrowckConsumer<'tcx>>,
 }
 
 impl<'tcx> BorrowCheckRootCtxt<'tcx> {
@@ -38,6 +38,10 @@ impl<'tcx> BorrowCheckRootCtxt<'tcx> {
         }
     }
 
+    pub(super) fn root_def_id(&self) -> LocalDefId {
+        self.root_def_id
+    }
+
     /// Collect all defining uses of opaque types inside of this typeck root. This
     /// expects the hidden type to be mapped to the definition parameters of the opaque
     /// and errors if we end up with distinct hidden types.
@@ -67,6 +71,13 @@ impl<'tcx> BorrowCheckRootCtxt<'tcx> {
         }
     }
 
+    pub(super) fn get_concrete_opaque_type(
+        &mut self,
+        def_id: LocalDefId,
+    ) -> Option<EarlyBinder<'tcx, OpaqueHiddenType<'tcx>>> {
+        self.concrete_opaque_types.0.get(&def_id).map(|ty| EarlyBinder::bind(*ty))
+    }
+
     pub(super) fn set_tainted_by_errors(&mut self, guar: ErrorGuaranteed) {
         self.tainted_by_errors = Some(guar);
     }
diff --git a/compiler/rustc_borrowck/src/type_check/canonical.rs b/compiler/rustc_borrowck/src/type_check/canonical.rs
index b3fa786a517..2627ed899a9 100644
--- a/compiler/rustc_borrowck/src/type_check/canonical.rs
+++ b/compiler/rustc_borrowck/src/type_check/canonical.rs
@@ -2,8 +2,9 @@ use std::fmt;
 
 use rustc_errors::ErrorGuaranteed;
 use rustc_infer::infer::canonical::Canonical;
+use rustc_infer::infer::outlives::env::RegionBoundPairs;
 use rustc_middle::bug;
-use rustc_middle::mir::ConstraintCategory;
+use rustc_middle::mir::{Body, ConstraintCategory};
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, Upcast};
 use rustc_span::Span;
 use rustc_span::def_id::DefId;
@@ -14,7 +15,68 @@ use rustc_trait_selection::traits::query::type_op::{self, TypeOpOutput};
 use tracing::{debug, instrument};
 
 use super::{Locations, NormalizeLocation, TypeChecker};
+use crate::BorrowckInferCtxt;
 use crate::diagnostics::ToUniverseInfo;
+use crate::type_check::{MirTypeckRegionConstraints, constraint_conversion};
+use crate::universal_regions::UniversalRegions;
+
+#[instrument(skip(infcx, constraints, op), level = "trace")]
+pub(crate) fn fully_perform_op_raw<'tcx, R: fmt::Debug, Op>(
+    infcx: &BorrowckInferCtxt<'tcx>,
+    body: &Body<'tcx>,
+    universal_regions: &UniversalRegions<'tcx>,
+    region_bound_pairs: &RegionBoundPairs<'tcx>,
+    known_type_outlives_obligations: &[ty::PolyTypeOutlivesPredicate<'tcx>],
+    constraints: &mut MirTypeckRegionConstraints<'tcx>,
+    locations: Locations,
+    category: ConstraintCategory<'tcx>,
+    op: Op,
+) -> Result<R, ErrorGuaranteed>
+where
+    Op: type_op::TypeOp<'tcx, Output = R>,
+    Op::ErrorInfo: ToUniverseInfo<'tcx>,
+{
+    let old_universe = infcx.universe();
+
+    let TypeOpOutput { output, constraints: query_constraints, error_info } =
+        op.fully_perform(infcx, infcx.root_def_id, locations.span(body))?;
+    if cfg!(debug_assertions) {
+        let data = infcx.take_and_reset_region_constraints();
+        if !data.is_empty() {
+            panic!("leftover region constraints: {data:#?}");
+        }
+    }
+
+    debug!(?output, ?query_constraints);
+
+    if let Some(data) = query_constraints {
+        constraint_conversion::ConstraintConversion::new(
+            infcx,
+            universal_regions,
+            region_bound_pairs,
+            known_type_outlives_obligations,
+            locations,
+            locations.span(body),
+            category,
+            constraints,
+        )
+        .convert_all(data);
+    }
+
+    // If the query has created new universes and errors are going to be emitted, register the
+    // cause of these new universes for improved diagnostics.
+    let universe = infcx.universe();
+    if old_universe != universe
+        && let Some(error_info) = error_info
+    {
+        let universe_info = error_info.to_universe_info(old_universe);
+        for u in (old_universe + 1)..=universe {
+            constraints.universe_causes.insert(u, universe_info.clone());
+        }
+    }
+
+    Ok(output)
+}
 
 impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
     /// Given some operation `op` that manipulates types, proves
@@ -38,36 +100,17 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         Op: type_op::TypeOp<'tcx, Output = R>,
         Op::ErrorInfo: ToUniverseInfo<'tcx>,
     {
-        let old_universe = self.infcx.universe();
-
-        let TypeOpOutput { output, constraints, error_info } =
-            op.fully_perform(self.infcx, locations.span(self.body))?;
-        if cfg!(debug_assertions) {
-            let data = self.infcx.take_and_reset_region_constraints();
-            if !data.is_empty() {
-                panic!("leftover region constraints: {data:#?}");
-            }
-        }
-
-        debug!(?output, ?constraints);
-
-        if let Some(data) = constraints {
-            self.push_region_constraints(locations, category, data);
-        }
-
-        // If the query has created new universes and errors are going to be emitted, register the
-        // cause of these new universes for improved diagnostics.
-        let universe = self.infcx.universe();
-        if old_universe != universe
-            && let Some(error_info) = error_info
-        {
-            let universe_info = error_info.to_universe_info(old_universe);
-            for u in (old_universe + 1)..=universe {
-                self.constraints.universe_causes.insert(u, universe_info.clone());
-            }
-        }
-
-        Ok(output)
+        fully_perform_op_raw(
+            self.infcx,
+            self.body,
+            self.universal_regions,
+            self.region_bound_pairs,
+            self.known_type_outlives_obligations,
+            self.constraints,
+            locations,
+            category,
+            op,
+        )
     }
 
     pub(super) fn instantiate_canonical<T>(
diff --git a/compiler/rustc_borrowck/src/type_check/constraint_conversion.rs b/compiler/rustc_borrowck/src/type_check/constraint_conversion.rs
index 9bb96b94506..703223e2e54 100644
--- a/compiler/rustc_borrowck/src/type_check/constraint_conversion.rs
+++ b/compiler/rustc_borrowck/src/type_check/constraint_conversion.rs
@@ -1,10 +1,10 @@
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir::def_id::LocalDefId;
+use rustc_infer::infer::SubregionOrigin;
 use rustc_infer::infer::canonical::QueryRegionConstraints;
 use rustc_infer::infer::outlives::env::RegionBoundPairs;
 use rustc_infer::infer::outlives::obligations::{TypeOutlives, TypeOutlivesDelegate};
 use rustc_infer::infer::region_constraints::{GenericKind, VerifyBound};
-use rustc_infer::infer::{InferCtxt, SubregionOrigin};
 use rustc_infer::traits::query::type_op::DeeplyNormalize;
 use rustc_middle::bug;
 use rustc_middle::ty::{
@@ -18,10 +18,12 @@ use crate::constraints::OutlivesConstraint;
 use crate::region_infer::TypeTest;
 use crate::type_check::{Locations, MirTypeckRegionConstraints};
 use crate::universal_regions::UniversalRegions;
-use crate::{ClosureOutlivesSubject, ClosureRegionRequirements, ConstraintCategory};
+use crate::{
+    BorrowckInferCtxt, ClosureOutlivesSubject, ClosureRegionRequirements, ConstraintCategory,
+};
 
 pub(crate) struct ConstraintConversion<'a, 'tcx> {
-    infcx: &'a InferCtxt<'tcx>,
+    infcx: &'a BorrowckInferCtxt<'tcx>,
     universal_regions: &'a UniversalRegions<'tcx>,
     /// Each RBP `GK: 'a` is assumed to be true. These encode
     /// relationships like `T: 'a` that are added via implicit bounds
@@ -34,7 +36,6 @@ pub(crate) struct ConstraintConversion<'a, 'tcx> {
     /// logic expecting to see (e.g.) `ReStatic`, and if we supplied
     /// our special inference variable there, we would mess that up.
     region_bound_pairs: &'a RegionBoundPairs<'tcx>,
-    param_env: ty::ParamEnv<'tcx>,
     known_type_outlives_obligations: &'a [ty::PolyTypeOutlivesPredicate<'tcx>],
     locations: Locations,
     span: Span,
@@ -45,10 +46,9 @@ pub(crate) struct ConstraintConversion<'a, 'tcx> {
 
 impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
     pub(crate) fn new(
-        infcx: &'a InferCtxt<'tcx>,
+        infcx: &'a BorrowckInferCtxt<'tcx>,
         universal_regions: &'a UniversalRegions<'tcx>,
         region_bound_pairs: &'a RegionBoundPairs<'tcx>,
-        param_env: ty::ParamEnv<'tcx>,
         known_type_outlives_obligations: &'a [ty::PolyTypeOutlivesPredicate<'tcx>],
         locations: Locations,
         span: Span,
@@ -59,7 +59,6 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
             infcx,
             universal_regions,
             region_bound_pairs,
-            param_env,
             known_type_outlives_obligations,
             locations,
             span,
@@ -286,8 +285,11 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
             ConstraintCategory<'tcx>,
         )>,
     ) -> Ty<'tcx> {
-        match self.param_env.and(DeeplyNormalize { value: ty }).fully_perform(self.infcx, self.span)
-        {
+        match self.infcx.param_env.and(DeeplyNormalize { value: ty }).fully_perform(
+            self.infcx,
+            self.infcx.root_def_id,
+            self.span,
+        ) {
             Ok(TypeOpOutput { output: ty, constraints, .. }) => {
                 // FIXME(higher_ranked_auto): What should we do with the assumptions here?
                 if let Some(QueryRegionConstraints { outlives, assumptions: _ }) = constraints {
diff --git a/compiler/rustc_borrowck/src/type_check/free_region_relations.rs b/compiler/rustc_borrowck/src/type_check/free_region_relations.rs
index f642d34ea67..7bf2df91470 100644
--- a/compiler/rustc_borrowck/src/type_check/free_region_relations.rs
+++ b/compiler/rustc_borrowck/src/type_check/free_region_relations.rs
@@ -2,9 +2,9 @@ use rustc_data_structures::frozen::Frozen;
 use rustc_data_structures::transitive_relation::{TransitiveRelation, TransitiveRelationBuilder};
 use rustc_hir::def::DefKind;
 use rustc_infer::infer::canonical::QueryRegionConstraints;
+use rustc_infer::infer::outlives;
 use rustc_infer::infer::outlives::env::RegionBoundPairs;
 use rustc_infer::infer::region_constraints::GenericKind;
-use rustc_infer::infer::{InferCtxt, outlives};
 use rustc_infer::traits::query::type_op::DeeplyNormalize;
 use rustc_middle::mir::ConstraintCategory;
 use rustc_middle::traits::query::OutlivesBound;
@@ -14,6 +14,7 @@ use rustc_trait_selection::traits::query::type_op::{self, TypeOp};
 use tracing::{debug, instrument};
 use type_op::TypeOpOutput;
 
+use crate::BorrowckInferCtxt;
 use crate::type_check::{Locations, MirTypeckRegionConstraints, constraint_conversion};
 use crate::universal_regions::UniversalRegions;
 
@@ -47,14 +48,12 @@ pub(crate) struct CreateResult<'tcx> {
 }
 
 pub(crate) fn create<'tcx>(
-    infcx: &InferCtxt<'tcx>,
-    param_env: ty::ParamEnv<'tcx>,
+    infcx: &BorrowckInferCtxt<'tcx>,
     universal_regions: UniversalRegions<'tcx>,
     constraints: &mut MirTypeckRegionConstraints<'tcx>,
 ) -> CreateResult<'tcx> {
     UniversalRegionRelationsBuilder {
         infcx,
-        param_env,
         constraints,
         universal_regions,
         region_bound_pairs: Default::default(),
@@ -177,8 +176,7 @@ impl UniversalRegionRelations<'_> {
 }
 
 struct UniversalRegionRelationsBuilder<'a, 'tcx> {
-    infcx: &'a InferCtxt<'tcx>,
-    param_env: ty::ParamEnv<'tcx>,
+    infcx: &'a BorrowckInferCtxt<'tcx>,
     universal_regions: UniversalRegions<'tcx>,
     constraints: &'a mut MirTypeckRegionConstraints<'tcx>,
 
@@ -205,7 +203,7 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
 
         // Insert the `'a: 'b` we know from the predicates.
         // This does not consider the type-outlives.
-        let param_env = self.param_env;
+        let param_env = self.infcx.param_env;
         self.add_outlives_bounds(outlives::explicit_outlives_bounds(param_env));
 
         // - outlives is reflexive, so `'r: 'r` for every region `'r`
@@ -263,7 +261,7 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
             let TypeOpOutput { output: norm_ty, constraints: constraints_normalize, .. } =
                 param_env
                     .and(DeeplyNormalize { value: ty })
-                    .fully_perform(self.infcx, span)
+                    .fully_perform(self.infcx, self.infcx.root_def_id, span)
                     .unwrap_or_else(|guar| TypeOpOutput {
                         output: Ty::new_error(self.infcx.tcx, guar),
                         constraints: None,
@@ -298,8 +296,9 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
         // Add implied bounds from impl header.
         if matches!(tcx.def_kind(defining_ty_def_id), DefKind::AssocFn | DefKind::AssocConst) {
             for &(ty, _) in tcx.assumed_wf_types(tcx.local_parent(defining_ty_def_id)) {
-                let result: Result<_, ErrorGuaranteed> =
-                    param_env.and(DeeplyNormalize { value: ty }).fully_perform(self.infcx, span);
+                let result: Result<_, ErrorGuaranteed> = param_env
+                    .and(DeeplyNormalize { value: ty })
+                    .fully_perform(self.infcx, self.infcx.root_def_id, span);
                 let Ok(TypeOpOutput { output: norm_ty, constraints: c, .. }) = result else {
                     continue;
                 };
@@ -318,7 +317,6 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
                 self.infcx,
                 &self.universal_regions,
                 &self.region_bound_pairs,
-                param_env,
                 &known_type_outlives_obligations,
                 Locations::All(span),
                 span,
@@ -353,10 +351,11 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
                 output: normalized_outlives,
                 constraints: constraints_normalize,
                 error_info: _,
-            }) = self
-                .param_env
-                .and(DeeplyNormalize { value: outlives })
-                .fully_perform(self.infcx, span)
+            }) = self.infcx.param_env.and(DeeplyNormalize { value: outlives }).fully_perform(
+                self.infcx,
+                self.infcx.root_def_id,
+                span,
+            )
             else {
                 self.infcx.dcx().delayed_bug(format!("could not normalize {outlives:?}"));
                 return;
@@ -381,9 +380,10 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
         span: Span,
     ) -> Option<&'tcx QueryRegionConstraints<'tcx>> {
         let TypeOpOutput { output: bounds, constraints, .. } = self
+            .infcx
             .param_env
             .and(type_op::ImpliedOutlivesBounds { ty })
-            .fully_perform(self.infcx, span)
+            .fully_perform(self.infcx, self.infcx.root_def_id, span)
             .map_err(|_: ErrorGuaranteed| debug!("failed to compute implied bounds {:?}", ty))
             .ok()?;
         debug!(?bounds, ?constraints);
diff --git a/compiler/rustc_borrowck/src/type_check/liveness/trace.rs b/compiler/rustc_borrowck/src/type_check/liveness/trace.rs
index 5d30fa71e92..b704d8f0a76 100644
--- a/compiler/rustc_borrowck/src/type_check/liveness/trace.rs
+++ b/compiler/rustc_borrowck/src/type_check/liveness/trace.rs
@@ -640,7 +640,7 @@ impl<'tcx> LivenessContext<'_, '_, 'tcx> {
 
         let op = typeck.infcx.param_env.and(DropckOutlives { dropped_ty });
 
-        match op.fully_perform(typeck.infcx, DUMMY_SP) {
+        match op.fully_perform(typeck.infcx, typeck.root_cx.root_def_id(), DUMMY_SP) {
             Ok(TypeOpOutput { output, constraints, .. }) => {
                 DropData { dropck_result: output, region_constraint_data: constraints }
             }
diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs
index c3aa205d5aa..0d363935f14 100644
--- a/compiler/rustc_borrowck/src/type_check/mod.rs
+++ b/compiler/rustc_borrowck/src/type_check/mod.rs
@@ -26,8 +26,7 @@ use rustc_middle::ty::adjustment::PointerCoercion;
 use rustc_middle::ty::cast::CastTy;
 use rustc_middle::ty::{
     self, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, CoroutineArgsExt,
-    GenericArgsRef, OpaqueHiddenType, OpaqueTypeKey, RegionVid, Ty, TyCtxt, TypeVisitableExt,
-    UserArgs, UserTypeAnnotationIndex, fold_regions,
+    GenericArgsRef, Ty, TyCtxt, TypeVisitableExt, UserArgs, UserTypeAnnotationIndex, fold_regions,
 };
 use rustc_middle::{bug, span_bug};
 use rustc_mir_dataflow::move_paths::MoveData;
@@ -35,6 +34,7 @@ use rustc_mir_dataflow::points::DenseLocationMap;
 use rustc_span::def_id::CRATE_DEF_ID;
 use rustc_span::source_map::Spanned;
 use rustc_span::{Span, sym};
+use rustc_trait_selection::infer::InferCtxtExt;
 use rustc_trait_selection::traits::query::type_op::custom::scrape_region_constraints;
 use rustc_trait_selection::traits::query::type_op::{TypeOp, TypeOpOutput};
 use tracing::{debug, instrument, trace};
@@ -42,7 +42,6 @@ use tracing::{debug, instrument, trace};
 use crate::borrow_set::BorrowSet;
 use crate::constraints::{OutlivesConstraint, OutlivesConstraintSet};
 use crate::diagnostics::UniverseInfo;
-use crate::member_constraints::MemberConstraintSet;
 use crate::polonius::legacy::{PoloniusFacts, PoloniusLocationTable};
 use crate::polonius::{PoloniusContext, PoloniusLivenessContext};
 use crate::region_infer::TypeTest;
@@ -67,12 +66,11 @@ macro_rules! span_mirbug {
     })
 }
 
-mod canonical;
+pub(crate) mod canonical;
 mod constraint_conversion;
 pub(crate) mod free_region_relations;
 mod input_output;
 pub(crate) mod liveness;
-mod opaque_types;
 mod relate_tys;
 
 /// Type checks the given `mir` in the context of the inference
@@ -114,7 +112,6 @@ pub(crate) fn type_check<'tcx>(
         placeholder_index_to_region: IndexVec::default(),
         liveness_constraints: LivenessValues::with_specific_points(Rc::clone(&location_map)),
         outlives_constraints: OutlivesConstraintSet::default(),
-        member_constraints: MemberConstraintSet::default(),
         type_tests: Vec::default(),
         universe_causes: FxIndexMap::default(),
     };
@@ -124,7 +121,7 @@ pub(crate) fn type_check<'tcx>(
         region_bound_pairs,
         normalized_inputs_and_output,
         known_type_outlives_obligations,
-    } = free_region_relations::create(infcx, infcx.param_env, universal_regions, &mut constraints);
+    } = free_region_relations::create(infcx, universal_regions, &mut constraints);
 
     let pre_obligations = infcx.take_registered_region_obligations();
     assert!(
@@ -170,9 +167,6 @@ pub(crate) fn type_check<'tcx>(
 
     liveness::generate(&mut typeck, &location_map, move_data);
 
-    let opaque_type_values =
-        opaque_types::take_opaques_and_register_member_constraints(&mut typeck);
-
     // We're done with typeck, we can finalize the polonius liveness context for region inference.
     let polonius_context = typeck.polonius_liveness.take().map(|liveness_context| {
         PoloniusContext::create_from_liveness(
@@ -187,7 +181,6 @@ pub(crate) fn type_check<'tcx>(
     if let Some(guar) = universal_region_relations.universal_regions.encountered_re_error() {
         debug!("encountered an error region; removing constraints!");
         constraints.outlives_constraints = Default::default();
-        constraints.member_constraints = Default::default();
         constraints.type_tests = Default::default();
         root_cx.set_tainted_by_errors(guar);
         infcx.set_tainted_by_errors(guar);
@@ -196,7 +189,8 @@ pub(crate) fn type_check<'tcx>(
     MirTypeckResults {
         constraints,
         universal_region_relations,
-        opaque_type_values,
+        region_bound_pairs,
+        known_type_outlives_obligations,
         polonius_context,
     }
 }
@@ -245,7 +239,8 @@ struct TypeChecker<'a, 'tcx> {
 pub(crate) struct MirTypeckResults<'tcx> {
     pub(crate) constraints: MirTypeckRegionConstraints<'tcx>,
     pub(crate) universal_region_relations: Frozen<UniversalRegionRelations<'tcx>>,
-    pub(crate) opaque_type_values: FxIndexMap<OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>>,
+    pub(crate) region_bound_pairs: Frozen<RegionBoundPairs<'tcx>>,
+    pub(crate) known_type_outlives_obligations: Frozen<Vec<ty::PolyTypeOutlivesPredicate<'tcx>>>,
     pub(crate) polonius_context: Option<PoloniusContext>,
 }
 
@@ -277,8 +272,6 @@ pub(crate) struct MirTypeckRegionConstraints<'tcx> {
 
     pub(crate) outlives_constraints: OutlivesConstraintSet<'tcx>,
 
-    pub(crate) member_constraints: MemberConstraintSet<'tcx, RegionVid>,
-
     pub(crate) universe_causes: FxIndexMap<ty::UniverseIndex, UniverseInfo<'tcx>>,
 
     pub(crate) type_tests: Vec<TypeTest<'tcx>>,
@@ -287,7 +280,7 @@ pub(crate) struct MirTypeckRegionConstraints<'tcx> {
 impl<'tcx> MirTypeckRegionConstraints<'tcx> {
     /// Creates a `Region` for a given `PlaceholderRegion`, or returns the
     /// region that corresponds to a previously created one.
-    fn placeholder_region(
+    pub(crate) fn placeholder_region(
         &mut self,
         infcx: &InferCtxt<'tcx>,
         placeholder: ty::PlaceholderRegion,
@@ -380,14 +373,6 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         self.body
     }
 
-    fn to_region_vid(&mut self, r: ty::Region<'tcx>) -> RegionVid {
-        if let ty::RePlaceholder(placeholder) = r.kind() {
-            self.constraints.placeholder_region(self.infcx, placeholder).as_var()
-        } else {
-            self.universal_regions.to_region_vid(r)
-        }
-    }
-
     fn unsized_feature_enabled(&self) -> bool {
         self.tcx().features().unsized_fn_params()
     }
@@ -424,7 +409,6 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             self.infcx,
             self.universal_regions,
             self.region_bound_pairs,
-            self.infcx.param_env,
             self.known_type_outlives_obligations,
             locations,
             locations.span(self.body),
@@ -1471,68 +1455,79 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                     }
                     CastKind::PtrToPtr => {
                         let ty_from = op.ty(self.body, tcx);
-                        let cast_ty_from = CastTy::from_ty(ty_from);
-                        let cast_ty_to = CastTy::from_ty(*ty);
-                        match (cast_ty_from, cast_ty_to) {
-                            (Some(CastTy::Ptr(src)), Some(CastTy::Ptr(dst))) => {
-                                let src_tail = self.struct_tail(src.ty, location);
-                                let dst_tail = self.struct_tail(dst.ty, location);
-
-                                // This checks (lifetime part of) vtable validity for pointer casts,
-                                // which is irrelevant when there are aren't principal traits on
-                                // both sides (aka only auto traits).
-                                //
-                                // Note that other checks (such as denying `dyn Send` -> `dyn
-                                // Debug`) are in `rustc_hir_typeck`.
-                                if let ty::Dynamic(src_tty, _src_lt, ty::Dyn) = *src_tail.kind()
-                                    && let ty::Dynamic(dst_tty, dst_lt, ty::Dyn) = *dst_tail.kind()
-                                    && src_tty.principal().is_some()
-                                    && dst_tty.principal().is_some()
-                                {
-                                    // Remove auto traits.
-                                    // Auto trait checks are handled in `rustc_hir_typeck` as FCW.
-                                    let src_obj = Ty::new_dynamic(
-                                        tcx,
-                                        tcx.mk_poly_existential_predicates(
-                                            &src_tty.without_auto_traits().collect::<Vec<_>>(),
-                                        ),
-                                        // FIXME: Once we disallow casting `*const dyn Trait + 'short`
-                                        // to `*const dyn Trait + 'long`, then this can just be `src_lt`.
-                                        dst_lt,
-                                        ty::Dyn,
-                                    );
-                                    let dst_obj = Ty::new_dynamic(
-                                        tcx,
-                                        tcx.mk_poly_existential_predicates(
-                                            &dst_tty.without_auto_traits().collect::<Vec<_>>(),
-                                        ),
-                                        dst_lt,
-                                        ty::Dyn,
-                                    );
-
-                                    debug!(?src_tty, ?dst_tty, ?src_obj, ?dst_obj);
-
-                                    self.sub_types(
-                                        src_obj,
-                                        dst_obj,
-                                        location.to_locations(),
-                                        ConstraintCategory::Cast {
-                                            is_implicit_coercion: false,
-                                            unsize_to: None,
-                                        },
-                                    )
-                                    .unwrap();
-                                }
-                            }
-                            _ => {
-                                span_mirbug!(
-                                    self,
-                                    rvalue,
-                                    "Invalid PtrToPtr cast {:?} -> {:?}",
-                                    ty_from,
-                                    ty
-                                )
-                            }
+                        let Some(CastTy::Ptr(src)) = CastTy::from_ty(ty_from) else {
+                            unreachable!();
+                        };
+                        let Some(CastTy::Ptr(dst)) = CastTy::from_ty(*ty) else {
+                            unreachable!();
+                        };
+
+                        if self.infcx.type_is_sized_modulo_regions(self.infcx.param_env, dst.ty) {
+                            // Wide to thin ptr cast. This may even occur in an env with
+                            // impossible predicates, such as `where dyn Trait: Sized`.
+                            // In this case, we don't want to fall into the case below,
+                            // since the types may not actually be equatable, but it's
+                            // fine to perform this operation in an impossible env.
+                            let trait_ref = ty::TraitRef::new(
+                                tcx,
+                                tcx.require_lang_item(LangItem::Sized, self.last_span),
+                                [dst.ty],
+                            );
+                            self.prove_trait_ref(
+                                trait_ref,
+                                location.to_locations(),
+                                ConstraintCategory::Cast {
+                                    is_implicit_coercion: true,
+                                    unsize_to: None,
+                                },
+                            );
+                        } else if let ty::Dynamic(src_tty, _src_lt, ty::Dyn) =
+                            *self.struct_tail(src.ty, location).kind()
+                            && let ty::Dynamic(dst_tty, dst_lt, ty::Dyn) =
+                                *self.struct_tail(dst.ty, location).kind()
+                            && src_tty.principal().is_some()
+                            && dst_tty.principal().is_some()
+                        {
+                            // This checks (lifetime part of) vtable validity for pointer casts,
+                            // which is irrelevant when there are aren't principal traits on
+                            // both sides (aka only auto traits).
+                            //
+                            // Note that other checks (such as denying `dyn Send` -> `dyn
+                            // Debug`) are in `rustc_hir_typeck`.
+
+                            // Remove auto traits.
+                            // Auto trait checks are handled in `rustc_hir_typeck` as FCW.
+                            let src_obj = Ty::new_dynamic(
+                                tcx,
+                                tcx.mk_poly_existential_predicates(
+                                    &src_tty.without_auto_traits().collect::<Vec<_>>(),
+                                ),
+                                // FIXME: Once we disallow casting `*const dyn Trait + 'short`
+                                // to `*const dyn Trait + 'long`, then this can just be `src_lt`.
+                                dst_lt,
+                                ty::Dyn,
+                            );
+                            let dst_obj = Ty::new_dynamic(
+                                tcx,
+                                tcx.mk_poly_existential_predicates(
+                                    &dst_tty.without_auto_traits().collect::<Vec<_>>(),
+                                ),
+                                dst_lt,
+                                ty::Dyn,
+                            );
+
+                            debug!(?src_tty, ?dst_tty, ?src_obj, ?dst_obj);
+
+                            self.sub_types(
+                                src_obj,
+                                dst_obj,
+                                location.to_locations(),
+                                ConstraintCategory::Cast {
+                                    is_implicit_coercion: false,
+                                    unsize_to: None,
+                                },
+                            )
+                            .unwrap();
                         }
                     }
                     CastKind::Transmute => {
@@ -1773,10 +1768,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                     locations,
                 );
 
-                assert!(!matches!(
-                    tcx.impl_of_assoc(def_id).map(|imp| tcx.def_kind(imp)),
-                    Some(DefKind::Impl { of_trait: true })
-                ));
+                assert_eq!(tcx.trait_impl_of_assoc(def_id), None);
                 self.prove_predicates(
                     args.types().map(|ty| ty::ClauseKind::WellFormed(ty.into())),
                     locations,
@@ -1898,7 +1890,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             if !output_ty
                 .is_privately_uninhabited(self.tcx(), self.infcx.typing_env(self.infcx.param_env))
             {
-                span_mirbug!(self, term, "call to converging function {:?} w/o dest", sig);
+                span_mirbug!(self, term, "call to non-diverging function {:?} w/o dest", sig);
             }
         } else {
             let dest_ty = destination.ty(self.body, tcx).ty;
@@ -2477,12 +2469,12 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         args: GenericArgsRef<'tcx>,
         locations: Locations,
     ) -> ty::InstantiatedPredicates<'tcx> {
+        let root_def_id = self.root_cx.root_def_id();
         if let Some(closure_requirements) = &self.root_cx.closure_requirements(def_id) {
             constraint_conversion::ConstraintConversion::new(
                 self.infcx,
                 self.universal_regions,
                 self.region_bound_pairs,
-                self.infcx.param_env,
                 self.known_type_outlives_obligations,
                 locations,
                 self.body.span,             // irrelevant; will be overridden.
@@ -2492,9 +2484,8 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             .apply_closure_requirements(closure_requirements, def_id, args);
         }
 
-        // Now equate closure args to regions inherited from `typeck_root_def_id`. Fixes #98589.
-        let typeck_root_def_id = tcx.typeck_root_def_id(self.body.source.def_id());
-        let typeck_root_args = ty::GenericArgs::identity_for_item(tcx, typeck_root_def_id);
+        // Now equate closure args to regions inherited from `root_def_id`. Fixes #98589.
+        let typeck_root_args = ty::GenericArgs::identity_for_item(tcx, root_def_id);
 
         let parent_args = match tcx.def_kind(def_id) {
             // We don't want to dispatch on 3 different kind of closures here, so take
@@ -2569,17 +2560,14 @@ impl<'tcx> TypeOp<'tcx> for InstantiateOpaqueType<'tcx> {
     fn fully_perform(
         mut self,
         infcx: &InferCtxt<'tcx>,
+        root_def_id: LocalDefId,
         span: Span,
     ) -> Result<TypeOpOutput<'tcx, Self>, ErrorGuaranteed> {
-        let (mut output, region_constraints) = scrape_region_constraints(
-            infcx,
-            |ocx| {
+        let (mut output, region_constraints) =
+            scrape_region_constraints(infcx, root_def_id, "InstantiateOpaqueType", span, |ocx| {
                 ocx.register_obligations(self.obligations.clone());
                 Ok(())
-            },
-            "InstantiateOpaqueType",
-            span,
-        )?;
+            })?;
         self.region_constraints = Some(region_constraints);
         output.error_info = Some(self);
         Ok(output)
diff --git a/compiler/rustc_borrowck/src/type_check/opaque_types.rs b/compiler/rustc_borrowck/src/type_check/opaque_types.rs
deleted file mode 100644
index 5a422483eef..00000000000
--- a/compiler/rustc_borrowck/src/type_check/opaque_types.rs
+++ /dev/null
@@ -1,333 +0,0 @@
-use std::iter;
-
-use rustc_data_structures::fx::FxIndexMap;
-use rustc_middle::span_bug;
-use rustc_middle::ty::{
-    self, GenericArgKind, OpaqueHiddenType, OpaqueTypeKey, Ty, TyCtxt, TypeSuperVisitable,
-    TypeVisitable, TypeVisitableExt, TypeVisitor, fold_regions,
-};
-use tracing::{debug, trace};
-
-use super::{MemberConstraintSet, TypeChecker};
-
-/// Once we're done with typechecking the body, we take all the opaque types
-/// defined by this function and add their 'member constraints'.
-pub(super) fn take_opaques_and_register_member_constraints<'tcx>(
-    typeck: &mut TypeChecker<'_, 'tcx>,
-) -> FxIndexMap<OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>> {
-    let infcx = typeck.infcx;
-    // Annoying: to invoke `typeck.to_region_vid`, we need access to
-    // `typeck.constraints`, but we also want to be mutating
-    // `typeck.member_constraints`. For now, just swap out the value
-    // we want and replace at the end.
-    let mut member_constraints = std::mem::take(&mut typeck.constraints.member_constraints);
-    let opaque_types = infcx
-        .take_opaque_types()
-        .into_iter()
-        .map(|(opaque_type_key, hidden_type)| {
-            let hidden_type = infcx.resolve_vars_if_possible(hidden_type);
-            register_member_constraints(
-                typeck,
-                &mut member_constraints,
-                opaque_type_key,
-                hidden_type,
-            );
-            trace!("finalized opaque type {:?} to {:#?}", opaque_type_key, hidden_type.ty.kind());
-            if hidden_type.has_non_region_infer() {
-                span_bug!(hidden_type.span, "could not resolve {:?}", hidden_type.ty);
-            }
-
-            // Convert all regions to nll vars.
-            let (opaque_type_key, hidden_type) =
-                fold_regions(infcx.tcx, (opaque_type_key, hidden_type), |r, _| {
-                    ty::Region::new_var(infcx.tcx, typeck.to_region_vid(r))
-                });
-
-            (opaque_type_key, hidden_type)
-        })
-        .collect();
-    assert!(typeck.constraints.member_constraints.is_empty());
-    typeck.constraints.member_constraints = member_constraints;
-    opaque_types
-}
-
-/// Given the map `opaque_types` containing the opaque
-/// `impl Trait` types whose underlying, hidden types are being
-/// inferred, this method adds constraints to the regions
-/// appearing in those underlying hidden types to ensure that they
-/// at least do not refer to random scopes within the current
-/// function. These constraints are not (quite) sufficient to
-/// guarantee that the regions are actually legal values; that
-/// final condition is imposed after region inference is done.
-///
-/// # The Problem
-///
-/// Let's work through an example to explain how it works. Assume
-/// the current function is as follows:
-///
-/// ```text
-/// fn foo<'a, 'b>(..) -> (impl Bar<'a>, impl Bar<'b>)
-/// ```
-///
-/// Here, we have two `impl Trait` types whose values are being
-/// inferred (the `impl Bar<'a>` and the `impl
-/// Bar<'b>`). Conceptually, this is sugar for a setup where we
-/// define underlying opaque types (`Foo1`, `Foo2`) and then, in
-/// the return type of `foo`, we *reference* those definitions:
-///
-/// ```text
-/// type Foo1<'x> = impl Bar<'x>;
-/// type Foo2<'x> = impl Bar<'x>;
-/// fn foo<'a, 'b>(..) -> (Foo1<'a>, Foo2<'b>) { .. }
-///                    //  ^^^^ ^^
-///                    //  |    |
-///                    //  |    args
-///                    //  def_id
-/// ```
-///
-/// As indicating in the comments above, each of those references
-/// is (in the compiler) basically generic parameters (`args`)
-/// applied to the type of a suitable `def_id` (which identifies
-/// `Foo1` or `Foo2`).
-///
-/// Now, at this point in compilation, what we have done is to
-/// replace each of the references (`Foo1<'a>`, `Foo2<'b>`) with
-/// fresh inference variables C1 and C2. We wish to use the values
-/// of these variables to infer the underlying types of `Foo1` and
-/// `Foo2`. That is, this gives rise to higher-order (pattern) unification
-/// constraints like:
-///
-/// ```text
-/// for<'a> (Foo1<'a> = C1)
-/// for<'b> (Foo1<'b> = C2)
-/// ```
-///
-/// For these equation to be satisfiable, the types `C1` and `C2`
-/// can only refer to a limited set of regions. For example, `C1`
-/// can only refer to `'static` and `'a`, and `C2` can only refer
-/// to `'static` and `'b`. The job of this function is to impose that
-/// constraint.
-///
-/// Up to this point, C1 and C2 are basically just random type
-/// inference variables, and hence they may contain arbitrary
-/// regions. In fact, it is fairly likely that they do! Consider
-/// this possible definition of `foo`:
-///
-/// ```text
-/// fn foo<'a, 'b>(x: &'a i32, y: &'b i32) -> (impl Bar<'a>, impl Bar<'b>) {
-///         (&*x, &*y)
-///     }
-/// ```
-///
-/// Here, the values for the concrete types of the two impl
-/// traits will include inference variables:
-///
-/// ```text
-/// &'0 i32
-/// &'1 i32
-/// ```
-///
-/// Ordinarily, the subtyping rules would ensure that these are
-/// sufficiently large. But since `impl Bar<'a>` isn't a specific
-/// type per se, we don't get such constraints by default. This
-/// is where this function comes into play. It adds extra
-/// constraints to ensure that all the regions which appear in the
-/// inferred type are regions that could validly appear.
-///
-/// This is actually a bit of a tricky constraint in general. We
-/// want to say that each variable (e.g., `'0`) can only take on
-/// values that were supplied as arguments to the opaque type
-/// (e.g., `'a` for `Foo1<'a>`) or `'static`, which is always in
-/// scope. We don't have a constraint quite of this kind in the current
-/// region checker.
-///
-/// # The Solution
-///
-/// We generally prefer to make `<=` constraints, since they
-/// integrate best into the region solver. To do that, we find the
-/// "minimum" of all the arguments that appear in the args: that
-/// is, some region which is less than all the others. In the case
-/// of `Foo1<'a>`, that would be `'a` (it's the only choice, after
-/// all). Then we apply that as a least bound to the variables
-/// (e.g., `'a <= '0`).
-///
-/// In some cases, there is no minimum. Consider this example:
-///
-/// ```text
-/// fn baz<'a, 'b>() -> impl Trait<'a, 'b> { ... }
-/// ```
-///
-/// Here we would report a more complex "in constraint", like `'r
-/// in ['a, 'b, 'static]` (where `'r` is some region appearing in
-/// the hidden type).
-///
-/// # Constrain regions, not the hidden concrete type
-///
-/// Note that generating constraints on each region `Rc` is *not*
-/// the same as generating an outlives constraint on `Tc` itself.
-/// For example, if we had a function like this:
-///
-/// ```
-/// # #![feature(type_alias_impl_trait)]
-/// # fn main() {}
-/// # trait Foo<'a> {}
-/// # impl<'a, T> Foo<'a> for (&'a u32, T) {}
-/// fn foo<'a, T>(x: &'a u32, y: T) -> impl Foo<'a> {
-///   (x, y)
-/// }
-///
-/// // Equivalent to:
-/// # mod dummy { use super::*;
-/// type FooReturn<'a, T> = impl Foo<'a>;
-/// #[define_opaque(FooReturn)]
-/// fn foo<'a, T>(x: &'a u32, y: T) -> FooReturn<'a, T> {
-///   (x, y)
-/// }
-/// # }
-/// ```
-///
-/// then the hidden type `Tc` would be `(&'0 u32, T)` (where `'0`
-/// is an inference variable). If we generated a constraint that
-/// `Tc: 'a`, then this would incorrectly require that `T: 'a` --
-/// but this is not necessary, because the opaque type we
-/// create will be allowed to reference `T`. So we only generate a
-/// constraint that `'0: 'a`.
-fn register_member_constraints<'tcx>(
-    typeck: &mut TypeChecker<'_, 'tcx>,
-    member_constraints: &mut MemberConstraintSet<'tcx, ty::RegionVid>,
-    opaque_type_key: OpaqueTypeKey<'tcx>,
-    OpaqueHiddenType { span, ty: hidden_ty }: OpaqueHiddenType<'tcx>,
-) {
-    let tcx = typeck.tcx();
-    let hidden_ty = typeck.infcx.resolve_vars_if_possible(hidden_ty);
-    debug!(?hidden_ty);
-
-    let variances = tcx.variances_of(opaque_type_key.def_id);
-    debug!(?variances);
-
-    // For a case like `impl Foo<'a, 'b>`, we would generate a constraint
-    // `'r in ['a, 'b, 'static]` for each region `'r` that appears in the
-    // hidden type (i.e., it must be equal to `'a`, `'b`, or `'static`).
-    //
-    // `conflict1` and `conflict2` are the two region bounds that we
-    // detected which were unrelated. They are used for diagnostics.
-
-    // Create the set of choice regions: each region in the hidden
-    // type can be equal to any of the region parameters of the
-    // opaque type definition.
-    let fr_static = typeck.universal_regions.fr_static;
-    let choice_regions: Vec<_> = opaque_type_key
-        .args
-        .iter()
-        .enumerate()
-        .filter(|(i, _)| variances[*i] == ty::Invariant)
-        .filter_map(|(_, arg)| match arg.kind() {
-            GenericArgKind::Lifetime(r) => Some(typeck.to_region_vid(r)),
-            GenericArgKind::Type(_) | GenericArgKind::Const(_) => None,
-        })
-        .chain(iter::once(fr_static))
-        .collect();
-
-    // FIXME(#42940): This should use the `FreeRegionsVisitor`, but that's
-    // not currently sound until we have existential regions.
-    hidden_ty.visit_with(&mut ConstrainOpaqueTypeRegionVisitor {
-        tcx,
-        op: |r| {
-            member_constraints.add_member_constraint(
-                opaque_type_key,
-                hidden_ty,
-                span,
-                typeck.to_region_vid(r),
-                &choice_regions,
-            )
-        },
-    });
-}
-
-/// Visitor that requires that (almost) all regions in the type visited outlive
-/// `least_region`. We cannot use `push_outlives_components` because regions in
-/// closure signatures are not included in their outlives components. We need to
-/// ensure all regions outlive the given bound so that we don't end up with,
-/// say, `ReVar` appearing in a return type and causing ICEs when other
-/// functions end up with region constraints involving regions from other
-/// functions.
-///
-/// We also cannot use `for_each_free_region` because for closures it includes
-/// the regions parameters from the enclosing item.
-///
-/// We ignore any type parameters because impl trait values are assumed to
-/// capture all the in-scope type parameters.
-struct ConstrainOpaqueTypeRegionVisitor<'tcx, OP: FnMut(ty::Region<'tcx>)> {
-    tcx: TyCtxt<'tcx>,
-    op: OP,
-}
-
-impl<'tcx, OP> TypeVisitor<TyCtxt<'tcx>> for ConstrainOpaqueTypeRegionVisitor<'tcx, OP>
-where
-    OP: FnMut(ty::Region<'tcx>),
-{
-    fn visit_region(&mut self, r: ty::Region<'tcx>) {
-        match r.kind() {
-            // ignore bound regions, keep visiting
-            ty::ReBound(_, _) => {}
-            _ => (self.op)(r),
-        }
-    }
-
-    fn visit_ty(&mut self, ty: Ty<'tcx>) {
-        // We're only interested in types involving regions
-        if !ty.flags().intersects(ty::TypeFlags::HAS_FREE_REGIONS) {
-            return;
-        }
-
-        match *ty.kind() {
-            ty::Closure(_, args) => {
-                // Skip lifetime parameters of the enclosing item(s)
-
-                for upvar in args.as_closure().upvar_tys() {
-                    upvar.visit_with(self);
-                }
-                args.as_closure().sig_as_fn_ptr_ty().visit_with(self);
-            }
-
-            ty::CoroutineClosure(_, args) => {
-                // Skip lifetime parameters of the enclosing item(s)
-
-                for upvar in args.as_coroutine_closure().upvar_tys() {
-                    upvar.visit_with(self);
-                }
-
-                args.as_coroutine_closure().signature_parts_ty().visit_with(self);
-            }
-
-            ty::Coroutine(_, args) => {
-                // Skip lifetime parameters of the enclosing item(s)
-                // Also skip the witness type, because that has no free regions.
-
-                for upvar in args.as_coroutine().upvar_tys() {
-                    upvar.visit_with(self);
-                }
-                args.as_coroutine().return_ty().visit_with(self);
-                args.as_coroutine().yield_ty().visit_with(self);
-                args.as_coroutine().resume_ty().visit_with(self);
-            }
-
-            ty::Alias(kind, ty::AliasTy { def_id, args, .. })
-                if let Some(variances) = self.tcx.opt_alias_variances(kind, def_id) =>
-            {
-                // Skip lifetime parameters that are not captured, since they do
-                // not need member constraints registered for them; we'll erase
-                // them (and hopefully in the future replace them with placeholders).
-                for (v, s) in std::iter::zip(variances, args.iter()) {
-                    if *v != ty::Bivariant {
-                        s.visit_with(self);
-                    }
-                }
-            }
-
-            _ => {
-                ty.super_visit_with(self);
-            }
-        }
-    }
-}
diff --git a/compiler/rustc_borrowck/src/type_check/relate_tys.rs b/compiler/rustc_borrowck/src/type_check/relate_tys.rs
index 84ca9bad2c1..7ac2dff12f7 100644
--- a/compiler/rustc_borrowck/src/type_check/relate_tys.rs
+++ b/compiler/rustc_borrowck/src/type_check/relate_tys.rs
@@ -124,8 +124,13 @@ impl<'a, 'b, 'tcx> NllTypeRelating<'a, 'b, 'tcx> {
         // by using `ty_vid rel B` and then finally and end by equating `ty_vid` to
         // the opaque.
         let mut enable_subtyping = |ty, opaque_is_expected| {
-            let ty_vid = infcx.next_ty_var_id_in_universe(self.span(), ty::UniverseIndex::ROOT);
-
+            // We create the fresh inference variable in the highest universe.
+            // In theory we could limit it to the highest universe in the args of
+            // the opaque but that isn't really worth the effort.
+            //
+            // We'll make sure that the opaque type can actually name everything
+            // in its hidden type later on.
+            let ty_vid = infcx.next_ty_vid(self.span());
             let variance = if opaque_is_expected {
                 self.ambient_variance
             } else {
diff --git a/compiler/rustc_builtin_macros/Cargo.toml b/compiler/rustc_builtin_macros/Cargo.toml
index e56b9e641a1..9ca44d67150 100644
--- a/compiler/rustc_builtin_macros/Cargo.toml
+++ b/compiler/rustc_builtin_macros/Cargo.toml
@@ -30,6 +30,6 @@ rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec = "0.2.12"
-tracing = "0.1"
+thin-vec.workspace = true
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_builtin_macros/messages.ftl b/compiler/rustc_builtin_macros/messages.ftl
index ae186d744c4..358c0d3db46 100644
--- a/compiler/rustc_builtin_macros/messages.ftl
+++ b/compiler/rustc_builtin_macros/messages.ftl
@@ -222,6 +222,15 @@ builtin_macros_format_unused_args = multiple unused formatting arguments
 
 builtin_macros_format_use_positional = consider using a positional formatting argument instead
 
+builtin_macros_derive_from_wrong_target = `#[derive(From)]` used on {$kind}
+
+builtin_macros_derive_from_wrong_field_count = `#[derive(From)]` used on a struct with {$multiple_fields ->
+    [true] multiple fields
+    *[false] no fields
+}
+
+builtin_macros_derive_from_usage_note = `#[derive(From)]` can only be used on structs with exactly one field
+
 builtin_macros_multiple_default_attrs = multiple `#[default]` attributes
     .note = only one `#[default]` attribute is needed
     .label = `#[default]` used here
@@ -259,8 +268,6 @@ builtin_macros_only_one_argument = {$name} takes 1 argument
 
 builtin_macros_proc_macro = `proc-macro` crate types currently cannot export any items other than functions tagged with `#[proc_macro]`, `#[proc_macro_derive]`, or `#[proc_macro_attribute]`
 
-builtin_macros_proc_macro_attribute_only_be_used_on_bare_functions = the `#[{$path}]` attribute may only be used on bare functions
-
 builtin_macros_proc_macro_attribute_only_usable_with_crate_type = the `#[{$path}]` attribute is only usable with crates of the `proc-macro` crate type
 
 builtin_macros_requires_cfg_pattern =
diff --git a/compiler/rustc_builtin_macros/src/assert.rs b/compiler/rustc_builtin_macros/src/assert.rs
index 855da5caa31..013258a1b4e 100644
--- a/compiler/rustc_builtin_macros/src/assert.rs
+++ b/compiler/rustc_builtin_macros/src/assert.rs
@@ -1,8 +1,8 @@
 mod context;
 
-use rustc_ast::token::Delimiter;
+use rustc_ast::token::{self, Delimiter};
 use rustc_ast::tokenstream::{DelimSpan, TokenStream};
-use rustc_ast::{DelimArgs, Expr, ExprKind, MacCall, Path, PathSegment, UnOp, token};
+use rustc_ast::{DelimArgs, Expr, ExprKind, MacCall, Path, PathSegment};
 use rustc_ast_pretty::pprust;
 use rustc_errors::PResult;
 use rustc_expand::base::{DummyResult, ExpandResult, ExtCtxt, MacEager, MacroExpanderResult};
@@ -29,7 +29,7 @@ pub(crate) fn expand_assert<'cx>(
 
     // `core::panic` and `std::panic` are different macros, so we use call-site
     // context to pick up whichever is currently in scope.
-    let call_site_span = cx.with_call_site_ctxt(span);
+    let call_site_span = cx.with_call_site_ctxt(cond_expr.span);
 
     let panic_path = || {
         if use_panic_2021(span) {
@@ -63,7 +63,7 @@ pub(crate) fn expand_assert<'cx>(
                 }),
             })),
         );
-        expr_if_not(cx, call_site_span, cond_expr, then, None)
+        assert_cond_check(cx, call_site_span, cond_expr, then)
     }
     // If `generic_assert` is enabled, generates rich captured outputs
     //
@@ -88,26 +88,33 @@ pub(crate) fn expand_assert<'cx>(
                 )),
             )],
         );
-        expr_if_not(cx, call_site_span, cond_expr, then, None)
+        assert_cond_check(cx, call_site_span, cond_expr, then)
     };
 
     ExpandResult::Ready(MacEager::expr(expr))
 }
 
+/// `assert!($cond_expr, $custom_message)`
 struct Assert {
     cond_expr: Box<Expr>,
     custom_message: Option<TokenStream>,
 }
 
-// if !{ ... } { ... } else { ... }
-fn expr_if_not(
-    cx: &ExtCtxt<'_>,
-    span: Span,
-    cond: Box<Expr>,
-    then: Box<Expr>,
-    els: Option<Box<Expr>>,
-) -> Box<Expr> {
-    cx.expr_if(span, cx.expr(span, ExprKind::Unary(UnOp::Not, cond)), then, els)
+/// `match <cond> { true => {} _ => <then> }`
+fn assert_cond_check(cx: &ExtCtxt<'_>, span: Span, cond: Box<Expr>, then: Box<Expr>) -> Box<Expr> {
+    // Instead of expanding to `if !<cond> { <then> }`, we expand to
+    // `match <cond> { true => {} _ => <then> }`.
+    // This allows us to always complain about mismatched types instead of "cannot apply unary
+    // operator `!` to type `X`" when passing an invalid `<cond>`, while also allowing `<cond>` to
+    // be `&true`.
+    let els = cx.expr_block(cx.block(span, thin_vec![]));
+    let mut arms = thin_vec![];
+    arms.push(cx.arm(span, cx.pat_lit(span, cx.expr_bool(span, true)), els));
+    arms.push(cx.arm(span, cx.pat_wild(span), then));
+
+    // We wrap the `match` in a statement to limit the length of any borrows introduced in the
+    // condition.
+    cx.expr_block(cx.block(span, [cx.stmt_expr(cx.expr_match(span, cond, arms))].into()))
 }
 
 fn parse_assert<'a>(cx: &ExtCtxt<'a>, sp: Span, stream: TokenStream) -> PResult<'a, Assert> {
diff --git a/compiler/rustc_builtin_macros/src/autodiff.rs b/compiler/rustc_builtin_macros/src/autodiff.rs
index a662840eda5..48d0795af5e 100644
--- a/compiler/rustc_builtin_macros/src/autodiff.rs
+++ b/compiler/rustc_builtin_macros/src/autodiff.rs
@@ -15,11 +15,12 @@ mod llvm_enzyme {
     use rustc_ast::tokenstream::*;
     use rustc_ast::visit::AssocCtxt::*;
     use rustc_ast::{
-        self as ast, AssocItemKind, BindingMode, ExprKind, FnRetTy, FnSig, Generics, ItemKind,
-        MetaItemInner, PatKind, QSelf, TyKind, Visibility,
+        self as ast, AngleBracketedArg, AngleBracketedArgs, AnonConst, AssocItemKind, BindingMode,
+        FnRetTy, FnSig, GenericArg, GenericArgs, GenericParamKind, Generics, ItemKind,
+        MetaItemInner, PatKind, Path, PathSegment, TyKind, Visibility,
     };
     use rustc_expand::base::{Annotatable, ExtCtxt};
-    use rustc_span::{Ident, Span, Symbol, kw, sym};
+    use rustc_span::{Ident, Span, Symbol, sym};
     use thin_vec::{ThinVec, thin_vec};
     use tracing::{debug, trace};
 
@@ -179,11 +180,8 @@ mod llvm_enzyme {
     }
 
     /// We expand the autodiff macro to generate a new placeholder function which passes
-    /// type-checking and can be called by users. The function body of the placeholder function will
-    /// later be replaced on LLVM-IR level, so the design of the body is less important and for now
-    /// should just prevent early inlining and optimizations which alter the function signature.
-    /// The exact signature of the generated function depends on the configuration provided by the
-    /// user, but here is an example:
+    /// type-checking and can be called by users. The exact signature of the generated function
+    /// depends on the configuration provided by the user, but here is an example:
     ///
     /// ```
     /// #[autodiff(cos_box, Reverse, Duplicated, Active)]
@@ -194,19 +192,12 @@ mod llvm_enzyme {
     /// which becomes expanded to:
     /// ```
     /// #[rustc_autodiff]
-    /// #[inline(never)]
     /// fn sin(x: &Box<f32>) -> f32 {
     ///     f32::sin(**x)
     /// }
     /// #[rustc_autodiff(Reverse, Duplicated, Active)]
-    /// #[inline(never)]
     /// fn cos_box(x: &Box<f32>, dx: &mut Box<f32>, dret: f32) -> f32 {
-    ///     unsafe {
-    ///         asm!("NOP");
-    ///     };
-    ///     ::core::hint::black_box(sin(x));
-    ///     ::core::hint::black_box((dx, dret));
-    ///     ::core::hint::black_box(sin(x))
+    ///     std::intrinsics::autodiff(sin::<>, cos_box::<>, (x, dx, dret))
     /// }
     /// ```
     /// FIXME(ZuseZ4): Once autodiff is enabled by default, make this a doc comment which is checked
@@ -227,16 +218,24 @@ mod llvm_enzyme {
         // first get information about the annotable item: visibility, signature, name and generic
         // parameters.
         // these will be used to generate the differentiated version of the function
-        let Some((vis, sig, primal, generics)) = (match &item {
-            Annotatable::Item(iitem) => extract_item_info(iitem),
+        let Some((vis, sig, primal, generics, impl_of_trait)) = (match &item {
+            Annotatable::Item(iitem) => {
+                extract_item_info(iitem).map(|(v, s, p, g)| (v, s, p, g, false))
+            }
             Annotatable::Stmt(stmt) => match &stmt.kind {
-                ast::StmtKind::Item(iitem) => extract_item_info(iitem),
+                ast::StmtKind::Item(iitem) => {
+                    extract_item_info(iitem).map(|(v, s, p, g)| (v, s, p, g, false))
+                }
                 _ => None,
             },
-            Annotatable::AssocItem(assoc_item, Impl { .. }) => match &assoc_item.kind {
-                ast::AssocItemKind::Fn(box ast::Fn { sig, ident, generics, .. }) => {
-                    Some((assoc_item.vis.clone(), sig.clone(), ident.clone(), generics.clone()))
-                }
+            Annotatable::AssocItem(assoc_item, Impl { of_trait }) => match &assoc_item.kind {
+                ast::AssocItemKind::Fn(box ast::Fn { sig, ident, generics, .. }) => Some((
+                    assoc_item.vis.clone(),
+                    sig.clone(),
+                    ident.clone(),
+                    generics.clone(),
+                    *of_trait,
+                )),
                 _ => None,
             },
             _ => None,
@@ -254,7 +253,6 @@ mod llvm_enzyme {
         };
 
         let has_ret = has_ret(&sig.decl.output);
-        let sig_span = ecx.with_call_site_ctxt(sig.span);
 
         // create TokenStream from vec elemtents:
         // meta_item doesn't have a .tokens field
@@ -323,19 +321,23 @@ mod llvm_enzyme {
         }
         let span = ecx.with_def_site_ctxt(expand_span);
 
-        let n_active: u32 = x
-            .input_activity
-            .iter()
-            .filter(|a| **a == DiffActivity::Active || **a == DiffActivity::ActiveOnly)
-            .count() as u32;
-        let (d_sig, new_args, idents, errored) = gen_enzyme_decl(ecx, &sig, &x, span);
-        let d_body = gen_enzyme_body(
-            ecx, &x, n_active, &sig, &d_sig, primal, &new_args, span, sig_span, idents, errored,
-            &generics,
+        let d_sig = gen_enzyme_decl(ecx, &sig, &x, span);
+
+        let d_body = ecx.block(
+            span,
+            thin_vec![call_autodiff(
+                ecx,
+                primal,
+                first_ident(&meta_item_vec[0]),
+                span,
+                &d_sig,
+                &generics,
+                impl_of_trait,
+            )],
         );
 
         // The first element of it is the name of the function to be generated
-        let asdf = Box::new(ast::Fn {
+        let d_fn = Box::new(ast::Fn {
             defaultness: ast::Defaultness::Final,
             sig: d_sig,
             ident: first_ident(&meta_item_vec[0]),
@@ -368,7 +370,7 @@ mod llvm_enzyme {
         let new_id = ecx.sess.psess.attr_id_generator.mk_attr_id();
         let inline_never = outer_normal_attr(&inline_never_attr, new_id, span);
 
-        // We're avoid duplicating the attributes `#[rustc_autodiff]` and `#[inline(never)]`.
+        // We're avoid duplicating the attribute `#[rustc_autodiff]`.
         fn same_attribute(attr: &ast::AttrKind, item: &ast::AttrKind) -> bool {
             match (attr, item) {
                 (ast::AttrKind::Normal(a), ast::AttrKind::Normal(b)) => {
@@ -381,14 +383,16 @@ mod llvm_enzyme {
             }
         }
 
+        let mut has_inline_never = false;
+
         // Don't add it multiple times:
         let orig_annotatable: Annotatable = match item {
             Annotatable::Item(ref mut iitem) => {
                 if !iitem.attrs.iter().any(|a| same_attribute(&a.kind, &attr.kind)) {
                     iitem.attrs.push(attr);
                 }
-                if !iitem.attrs.iter().any(|a| same_attribute(&a.kind, &inline_never.kind)) {
-                    iitem.attrs.push(inline_never.clone());
+                if iitem.attrs.iter().any(|a| same_attribute(&a.kind, &inline_never.kind)) {
+                    has_inline_never = true;
                 }
                 Annotatable::Item(iitem.clone())
             }
@@ -396,8 +400,8 @@ mod llvm_enzyme {
                 if !assoc_item.attrs.iter().any(|a| same_attribute(&a.kind, &attr.kind)) {
                     assoc_item.attrs.push(attr);
                 }
-                if !assoc_item.attrs.iter().any(|a| same_attribute(&a.kind, &inline_never.kind)) {
-                    assoc_item.attrs.push(inline_never.clone());
+                if assoc_item.attrs.iter().any(|a| same_attribute(&a.kind, &inline_never.kind)) {
+                    has_inline_never = true;
                 }
                 Annotatable::AssocItem(assoc_item.clone(), i)
             }
@@ -407,9 +411,8 @@ mod llvm_enzyme {
                         if !iitem.attrs.iter().any(|a| same_attribute(&a.kind, &attr.kind)) {
                             iitem.attrs.push(attr);
                         }
-                        if !iitem.attrs.iter().any(|a| same_attribute(&a.kind, &inline_never.kind))
-                        {
-                            iitem.attrs.push(inline_never.clone());
+                        if iitem.attrs.iter().any(|a| same_attribute(&a.kind, &inline_never.kind)) {
+                            has_inline_never = true;
                         }
                     }
                     _ => unreachable!("stmt kind checked previously"),
@@ -428,12 +431,21 @@ mod llvm_enzyme {
             tokens: ts,
         });
 
+        let new_id = ecx.sess.psess.attr_id_generator.mk_attr_id();
         let d_attr = outer_normal_attr(&rustc_ad_attr, new_id, span);
+
+        // If the source function has the `#[inline(never)]` attribute, we'll also add it to the diff function
+        let mut d_attrs = thin_vec![d_attr];
+
+        if has_inline_never {
+            d_attrs.push(inline_never);
+        }
+
         let d_annotatable = match &item {
             Annotatable::AssocItem(_, _) => {
-                let assoc_item: AssocItemKind = ast::AssocItemKind::Fn(asdf);
+                let assoc_item: AssocItemKind = ast::AssocItemKind::Fn(d_fn);
                 let d_fn = Box::new(ast::AssocItem {
-                    attrs: thin_vec![d_attr, inline_never],
+                    attrs: d_attrs,
                     id: ast::DUMMY_NODE_ID,
                     span,
                     vis,
@@ -443,13 +455,13 @@ mod llvm_enzyme {
                 Annotatable::AssocItem(d_fn, Impl { of_trait: false })
             }
             Annotatable::Item(_) => {
-                let mut d_fn = ecx.item(span, thin_vec![d_attr, inline_never], ItemKind::Fn(asdf));
+                let mut d_fn = ecx.item(span, d_attrs, ItemKind::Fn(d_fn));
                 d_fn.vis = vis;
 
                 Annotatable::Item(d_fn)
             }
             Annotatable::Stmt(_) => {
-                let mut d_fn = ecx.item(span, thin_vec![d_attr, inline_never], ItemKind::Fn(asdf));
+                let mut d_fn = ecx.item(span, d_attrs, ItemKind::Fn(d_fn));
                 d_fn.vis = vis;
 
                 Annotatable::Stmt(Box::new(ast::Stmt {
@@ -484,282 +496,95 @@ mod llvm_enzyme {
         ty
     }
 
-    // Will generate a body of the type:
+    // Generate `autodiff` intrinsic call
     // ```
-    // {
-    //   unsafe {
-    //   asm!("NOP");
-    //   }
-    //   ::core::hint::black_box(primal(args));
-    //   ::core::hint::black_box((args, ret));
-    //   <This part remains to be done by following function>
-    // }
+    // std::intrinsics::autodiff(source, diff, (args))
     // ```
-    fn init_body_helper(
+    fn call_autodiff(
         ecx: &ExtCtxt<'_>,
-        span: Span,
         primal: Ident,
-        new_names: &[String],
-        sig_span: Span,
-        new_decl_span: Span,
-        idents: &[Ident],
-        errored: bool,
+        diff: Ident,
+        span: Span,
+        d_sig: &FnSig,
         generics: &Generics,
-    ) -> (Box<ast::Block>, Box<ast::Expr>, Box<ast::Expr>, Box<ast::Expr>) {
-        let blackbox_path = ecx.std_path(&[sym::hint, sym::black_box]);
-        let noop = ast::InlineAsm {
-            asm_macro: ast::AsmMacro::Asm,
-            template: vec![ast::InlineAsmTemplatePiece::String("NOP".into())],
-            template_strs: Box::new([]),
-            operands: vec![],
-            clobber_abis: vec![],
-            options: ast::InlineAsmOptions::PURE | ast::InlineAsmOptions::NOMEM,
-            line_spans: vec![],
-        };
-        let noop_expr = ecx.expr_asm(span, Box::new(noop));
-        let unsf = ast::BlockCheckMode::Unsafe(ast::UnsafeSource::CompilerGenerated);
-        let unsf_block = ast::Block {
-            stmts: thin_vec![ecx.stmt_semi(noop_expr)],
-            id: ast::DUMMY_NODE_ID,
-            tokens: None,
-            rules: unsf,
+        is_impl: bool,
+    ) -> rustc_ast::Stmt {
+        let primal_path_expr = gen_turbofish_expr(ecx, primal, generics, span, is_impl);
+        let diff_path_expr = gen_turbofish_expr(ecx, diff, generics, span, is_impl);
+
+        let tuple_expr = ecx.expr_tuple(
             span,
-        };
-        let unsf_expr = ecx.expr_block(Box::new(unsf_block));
-        let blackbox_call_expr = ecx.expr_path(ecx.path(span, blackbox_path));
-        let primal_call = gen_primal_call(ecx, span, primal, idents, generics);
-        let black_box_primal_call = ecx.expr_call(
-            new_decl_span,
-            blackbox_call_expr.clone(),
-            thin_vec![primal_call.clone()],
+            d_sig
+                .decl
+                .inputs
+                .iter()
+                .map(|arg| match arg.pat.kind {
+                    PatKind::Ident(_, ident, _) => ecx.expr_path(ecx.path_ident(span, ident)),
+                    _ => todo!(),
+                })
+                .collect::<ThinVec<_>>()
+                .into(),
         );
-        let tup_args = new_names
-            .iter()
-            .map(|arg| ecx.expr_path(ecx.path_ident(span, Ident::from_str(arg))))
-            .collect();
 
-        let black_box_remaining_args = ecx.expr_call(
-            sig_span,
-            blackbox_call_expr.clone(),
-            thin_vec![ecx.expr_tuple(sig_span, tup_args)],
+        let enzyme_path_idents = ecx.std_path(&[sym::intrinsics, sym::autodiff]);
+        let enzyme_path = ecx.path(span, enzyme_path_idents);
+        let call_expr = ecx.expr_call(
+            span,
+            ecx.expr_path(enzyme_path),
+            vec![primal_path_expr, diff_path_expr, tuple_expr].into(),
         );
 
-        let mut body = ecx.block(span, ThinVec::new());
-        body.stmts.push(ecx.stmt_semi(unsf_expr));
-
-        // This uses primal args which won't be available if we errored before
-        if !errored {
-            body.stmts.push(ecx.stmt_semi(black_box_primal_call.clone()));
-        }
-        body.stmts.push(ecx.stmt_semi(black_box_remaining_args));
-
-        (body, primal_call, black_box_primal_call, blackbox_call_expr)
+        ecx.stmt_expr(call_expr)
     }
 
-    /// We only want this function to type-check, since we will replace the body
-    /// later on llvm level. Using `loop {}` does not cover all return types anymore,
-    /// so instead we manually build something that should pass the type checker.
-    /// We also add a inline_asm line, as one more barrier for rustc to prevent inlining
-    /// or const propagation. inline_asm will also triggers an Enzyme crash if due to another
-    /// bug would ever try to accidentally differentiate this placeholder function body.
-    /// Finally, we also add back_box usages of all input arguments, to prevent rustc
-    /// from optimizing any arguments away.
-    fn gen_enzyme_body(
+    // Generate turbofish expression from fn name and generics
+    // Given `foo` and `<A, B, C>` params, gen `foo::<A, B, C>`
+    // We use this expression when passing primal and diff function to the autodiff intrinsic
+    fn gen_turbofish_expr(
         ecx: &ExtCtxt<'_>,
-        x: &AutoDiffAttrs,
-        n_active: u32,
-        sig: &ast::FnSig,
-        d_sig: &ast::FnSig,
-        primal: Ident,
-        new_names: &[String],
-        span: Span,
-        sig_span: Span,
-        idents: Vec<Ident>,
-        errored: bool,
+        ident: Ident,
         generics: &Generics,
-    ) -> Box<ast::Block> {
-        let new_decl_span = d_sig.span;
-
-        // Just adding some default inline-asm and black_box usages to prevent early inlining
-        // and optimizations which alter the function signature.
-        //
-        // The bb_primal_call is the black_box call of the primal function. We keep it around,
-        // since it has the convenient property of returning the type of the primal function,
-        // Remember, we only care to match types here.
-        // No matter which return we pick, we always wrap it into a std::hint::black_box call,
-        // to prevent rustc from propagating it into the caller.
-        let (mut body, primal_call, bb_primal_call, bb_call_expr) = init_body_helper(
-            ecx,
-            span,
-            primal,
-            new_names,
-            sig_span,
-            new_decl_span,
-            &idents,
-            errored,
-            generics,
-        );
-
-        if !has_ret(&d_sig.decl.output) {
-            // there is no return type that we have to match, () works fine.
-            return body;
-        }
-
-        // Everything from here onwards just tries to fulfil the return type. Fun!
-
-        // having an active-only return means we'll drop the original return type.
-        // So that can be treated identical to not having one in the first place.
-        let primal_ret = has_ret(&sig.decl.output) && !x.has_active_only_ret();
-
-        if primal_ret && n_active == 0 && x.mode.is_rev() {
-            // We only have the primal ret.
-            body.stmts.push(ecx.stmt_expr(bb_primal_call));
-            return body;
-        }
-
-        if !primal_ret && n_active == 1 {
-            // Again no tuple return, so return default float val.
-            let ty = match d_sig.decl.output {
-                FnRetTy::Ty(ref ty) => ty.clone(),
-                FnRetTy::Default(span) => {
-                    panic!("Did not expect Default ret ty: {:?}", span);
+        span: Span,
+        is_impl: bool,
+    ) -> Box<ast::Expr> {
+        let generic_args = generics
+            .params
+            .iter()
+            .filter_map(|p| match &p.kind {
+                GenericParamKind::Type { .. } => {
+                    let path = ast::Path::from_ident(p.ident);
+                    let ty = ecx.ty_path(path);
+                    Some(AngleBracketedArg::Arg(GenericArg::Type(ty)))
                 }
-            };
-            let arg = ty.kind.is_simple_path().unwrap();
-            let tmp = ecx.def_site_path(&[arg, kw::Default]);
-            let default_call_expr = ecx.expr_path(ecx.path(span, tmp));
-            let default_call_expr = ecx.expr_call(new_decl_span, default_call_expr, thin_vec![]);
-            body.stmts.push(ecx.stmt_expr(default_call_expr));
-            return body;
-        }
-
-        let mut exprs: Box<ast::Expr> = primal_call;
-        let d_ret_ty = match d_sig.decl.output {
-            FnRetTy::Ty(ref ty) => ty.clone(),
-            FnRetTy::Default(span) => {
-                panic!("Did not expect Default ret ty: {:?}", span);
-            }
-        };
-        if x.mode.is_fwd() {
-            // Fwd mode is easy. If the return activity is Const, we support arbitrary types.
-            // Otherwise, we only support a scalar, a pair of scalars, or an array of scalars.
-            // We checked that (on a best-effort base) in the preceding gen_enzyme_decl function.
-            // In all three cases, we can return `std::hint::black_box(<T>::default())`.
-            if x.ret_activity == DiffActivity::Const {
-                // Here we call the primal function, since our dummy function has the same return
-                // type due to the Const return activity.
-                exprs = ecx.expr_call(new_decl_span, bb_call_expr, thin_vec![exprs]);
-            } else {
-                let q = QSelf { ty: d_ret_ty, path_span: span, position: 0 };
-                let y = ExprKind::Path(
-                    Some(Box::new(q)),
-                    ecx.path_ident(span, Ident::with_dummy_span(kw::Default)),
-                );
-                let default_call_expr = ecx.expr(span, y);
-                let default_call_expr =
-                    ecx.expr_call(new_decl_span, default_call_expr, thin_vec![]);
-                exprs = ecx.expr_call(new_decl_span, bb_call_expr, thin_vec![default_call_expr]);
-            }
-        } else if x.mode.is_rev() {
-            if x.width == 1 {
-                // We either have `-> ArbitraryType` or `-> (ArbitraryType, repeated_float_scalars)`.
-                match d_ret_ty.kind {
-                    TyKind::Tup(ref args) => {
-                        // We have a tuple return type. We need to create a tuple of the same size
-                        // and fill it with default values.
-                        let mut exprs2 = thin_vec![exprs];
-                        for arg in args.iter().skip(1) {
-                            let arg = arg.kind.is_simple_path().unwrap();
-                            let tmp = ecx.def_site_path(&[arg, kw::Default]);
-                            let default_call_expr = ecx.expr_path(ecx.path(span, tmp));
-                            let default_call_expr =
-                                ecx.expr_call(new_decl_span, default_call_expr, thin_vec![]);
-                            exprs2.push(default_call_expr);
-                        }
-                        exprs = ecx.expr_tuple(new_decl_span, exprs2);
-                    }
-                    _ => {
-                        // Interestingly, even the `-> ArbitraryType` case
-                        // ends up getting matched and handled correctly above,
-                        // so we don't have to handle any other case for now.
-                        panic!("Unsupported return type: {:?}", d_ret_ty);
-                    }
+                GenericParamKind::Const { .. } => {
+                    let expr = ecx.expr_path(ast::Path::from_ident(p.ident));
+                    let anon_const = AnonConst { id: ast::DUMMY_NODE_ID, value: expr };
+                    Some(AngleBracketedArg::Arg(GenericArg::Const(anon_const)))
                 }
-            }
-            exprs = ecx.expr_call(new_decl_span, bb_call_expr, thin_vec![exprs]);
-        } else {
-            unreachable!("Unsupported mode: {:?}", x.mode);
-        }
+                GenericParamKind::Lifetime { .. } => None,
+            })
+            .collect::<ThinVec<_>>();
 
-        body.stmts.push(ecx.stmt_expr(exprs));
-
-        body
-    }
+        let args: AngleBracketedArgs = AngleBracketedArgs { span, args: generic_args };
 
-    fn gen_primal_call(
-        ecx: &ExtCtxt<'_>,
-        span: Span,
-        primal: Ident,
-        idents: &[Ident],
-        generics: &Generics,
-    ) -> Box<ast::Expr> {
-        let has_self = idents.len() > 0 && idents[0].name == kw::SelfLower;
+        let segment = PathSegment {
+            ident,
+            id: ast::DUMMY_NODE_ID,
+            args: Some(Box::new(GenericArgs::AngleBracketed(args))),
+        };
 
-        if has_self {
-            let args: ThinVec<_> =
-                idents[1..].iter().map(|arg| ecx.expr_path(ecx.path_ident(span, *arg))).collect();
-            let self_expr = ecx.expr_self(span);
-            ecx.expr_method_call(span, self_expr, primal, args)
+        let segments = if is_impl {
+            thin_vec![
+                PathSegment { ident: Ident::from_str("Self"), id: ast::DUMMY_NODE_ID, args: None },
+                segment,
+            ]
         } else {
-            let args: ThinVec<_> =
-                idents.iter().map(|arg| ecx.expr_path(ecx.path_ident(span, *arg))).collect();
-            let mut primal_path = ecx.path_ident(span, primal);
-
-            let is_generic = !generics.params.is_empty();
-
-            match (is_generic, primal_path.segments.last_mut()) {
-                (true, Some(function_path)) => {
-                    let primal_generic_types = generics
-                        .params
-                        .iter()
-                        .filter(|param| matches!(param.kind, ast::GenericParamKind::Type { .. }));
-
-                    let generated_generic_types = primal_generic_types
-                        .map(|type_param| {
-                            let generic_param = TyKind::Path(
-                                None,
-                                ast::Path {
-                                    span,
-                                    segments: thin_vec![ast::PathSegment {
-                                        ident: type_param.ident,
-                                        args: None,
-                                        id: ast::DUMMY_NODE_ID,
-                                    }],
-                                    tokens: None,
-                                },
-                            );
-
-                            ast::AngleBracketedArg::Arg(ast::GenericArg::Type(Box::new(ast::Ty {
-                                id: type_param.id,
-                                span,
-                                kind: generic_param,
-                                tokens: None,
-                            })))
-                        })
-                        .collect();
-
-                    function_path.args =
-                        Some(Box::new(ast::GenericArgs::AngleBracketed(ast::AngleBracketedArgs {
-                            span,
-                            args: generated_generic_types,
-                        })));
-                }
-                _ => {}
-            }
+            thin_vec![segment]
+        };
 
-            let primal_call_expr = ecx.expr_path(primal_path);
-            ecx.expr_call(span, primal_call_expr, args)
-        }
+        let path = Path { span, segments, tokens: None };
+
+        ecx.expr_path(path)
     }
 
     // Generate the new function declaration. Const arguments are kept as is. Duplicated arguments must
@@ -778,7 +603,7 @@ mod llvm_enzyme {
         sig: &ast::FnSig,
         x: &AutoDiffAttrs,
         span: Span,
-    ) -> (ast::FnSig, Vec<String>, Vec<Ident>, bool) {
+    ) -> ast::FnSig {
         let dcx = ecx.sess.dcx();
         let has_ret = has_ret(&sig.decl.output);
         let sig_args = sig.decl.inputs.len() + if has_ret { 1 } else { 0 };
@@ -790,7 +615,7 @@ mod llvm_enzyme {
                 found: num_activities,
             });
             // This is not the right signature, but we can continue parsing.
-            return (sig.clone(), vec![], vec![], true);
+            return sig.clone();
         }
         assert!(sig.decl.inputs.len() == x.input_activity.len());
         assert!(has_ret == x.has_ret_activity());
@@ -833,7 +658,7 @@ mod llvm_enzyme {
 
         if errors {
             // This is not the right signature, but we can continue parsing.
-            return (sig.clone(), new_inputs, idents, true);
+            return sig.clone();
         }
 
         let unsafe_activities = x
@@ -1047,7 +872,7 @@ mod llvm_enzyme {
         }
         let d_sig = FnSig { header: d_header, decl: d_decl, span };
         trace!("Generated signature: {:?}", d_sig);
-        (d_sig, new_inputs, idents, false)
+        d_sig
     }
 }
 
diff --git a/compiler/rustc_builtin_macros/src/cfg_accessible.rs b/compiler/rustc_builtin_macros/src/cfg_accessible.rs
index f7d8f4aa783..48d80004cdd 100644
--- a/compiler/rustc_builtin_macros/src/cfg_accessible.rs
+++ b/compiler/rustc_builtin_macros/src/cfg_accessible.rs
@@ -1,9 +1,9 @@
 //! Implementation of the `#[cfg_accessible(path)]` attribute macro.
 
 use rustc_ast as ast;
+use rustc_attr_parsing::validate_attr;
 use rustc_expand::base::{Annotatable, ExpandResult, ExtCtxt, Indeterminate, MultiItemModifier};
 use rustc_feature::AttributeTemplate;
-use rustc_parse::validate_attr;
 use rustc_span::{Span, sym};
 
 use crate::errors;
diff --git a/compiler/rustc_builtin_macros/src/derive.rs b/compiler/rustc_builtin_macros/src/derive.rs
index a33eca43de5..09d827b0635 100644
--- a/compiler/rustc_builtin_macros/src/derive.rs
+++ b/compiler/rustc_builtin_macros/src/derive.rs
@@ -1,10 +1,10 @@
 use rustc_ast as ast;
 use rustc_ast::{GenericParamKind, ItemKind, MetaItemInner, MetaItemKind, StmtKind};
+use rustc_attr_parsing::validate_attr;
 use rustc_expand::base::{
     Annotatable, DeriveResolution, ExpandResult, ExtCtxt, Indeterminate, MultiItemModifier,
 };
 use rustc_feature::AttributeTemplate;
-use rustc_parse::validate_attr;
 use rustc_session::Session;
 use rustc_span::{ErrorGuaranteed, Ident, Span, sym};
 
diff --git a/compiler/rustc_builtin_macros/src/deriving/from.rs b/compiler/rustc_builtin_macros/src/deriving/from.rs
new file mode 100644
index 00000000000..ab25de7c917
--- /dev/null
+++ b/compiler/rustc_builtin_macros/src/deriving/from.rs
@@ -0,0 +1,133 @@
+use rustc_ast as ast;
+use rustc_ast::{ItemKind, VariantData};
+use rustc_errors::MultiSpan;
+use rustc_expand::base::{Annotatable, DummyResult, ExtCtxt};
+use rustc_span::{Ident, Span, kw, sym};
+use thin_vec::thin_vec;
+
+use crate::deriving::generic::ty::{Bounds, Path, PathKind, Ty};
+use crate::deriving::generic::{
+    BlockOrExpr, FieldlessVariantsStrategy, MethodDef, SubstructureFields, TraitDef,
+    combine_substructure,
+};
+use crate::deriving::pathvec_std;
+use crate::errors;
+
+/// Generate an implementation of the `From` trait, provided that `item`
+/// is a struct or a tuple struct with exactly one field.
+pub(crate) fn expand_deriving_from(
+    cx: &ExtCtxt<'_>,
+    span: Span,
+    mitem: &ast::MetaItem,
+    annotatable: &Annotatable,
+    push: &mut dyn FnMut(Annotatable),
+    is_const: bool,
+) {
+    let Annotatable::Item(item) = &annotatable else {
+        cx.dcx().bug("derive(From) used on something else than an item");
+    };
+
+    let err_span = || {
+        let item_span = item.kind.ident().map(|ident| ident.span).unwrap_or(item.span);
+        MultiSpan::from_spans(vec![span, item_span])
+    };
+
+    // `#[derive(From)]` is currently usable only on structs with exactly one field.
+    let field = match &item.kind {
+        ItemKind::Struct(_, _, data) => {
+            if let [field] = data.fields() {
+                Ok(field.clone())
+            } else {
+                let guar = cx.dcx().emit_err(errors::DeriveFromWrongFieldCount {
+                    span: err_span(),
+                    multiple_fields: data.fields().len() > 1,
+                });
+                Err(guar)
+            }
+        }
+        ItemKind::Enum(_, _, _) | ItemKind::Union(_, _, _) => {
+            let guar = cx.dcx().emit_err(errors::DeriveFromWrongTarget {
+                span: err_span(),
+                kind: &format!("{} {}", item.kind.article(), item.kind.descr()),
+            });
+            Err(guar)
+        }
+        _ => cx.dcx().bug("Invalid derive(From) ADT input"),
+    };
+
+    let from_type = Ty::AstTy(match field {
+        Ok(ref field) => field.ty.clone(),
+        Err(guar) => cx.ty(span, ast::TyKind::Err(guar)),
+    });
+
+    let path =
+        Path::new_(pathvec_std!(convert::From), vec![Box::new(from_type.clone())], PathKind::Std);
+
+    // Generate code like this:
+    //
+    // struct S(u32);
+    // #[automatically_derived]
+    // impl ::core::convert::From<u32> for S {
+    //     #[inline]
+    //     fn from(value: u32) -> S {
+    //         Self(value)
+    //     }
+    // }
+    let from_trait_def = TraitDef {
+        span,
+        path,
+        skip_path_as_bound: true,
+        needs_copy_as_bound_if_packed: false,
+        additional_bounds: Vec::new(),
+        supports_unions: false,
+        methods: vec![MethodDef {
+            name: sym::from,
+            generics: Bounds { bounds: vec![] },
+            explicit_self: false,
+            nonself_args: vec![(from_type, sym::value)],
+            ret_ty: Ty::Self_,
+            attributes: thin_vec![cx.attr_word(sym::inline, span)],
+            fieldless_variants_strategy: FieldlessVariantsStrategy::Default,
+            combine_substructure: combine_substructure(Box::new(|cx, span, substructure| {
+                let field = match field {
+                    Ok(ref field) => field,
+                    Err(guar) => {
+                        return BlockOrExpr::new_expr(DummyResult::raw_expr(span, Some(guar)));
+                    }
+                };
+
+                let self_kw = Ident::new(kw::SelfUpper, span);
+                let expr: Box<ast::Expr> = match substructure.fields {
+                    SubstructureFields::StaticStruct(variant, _) => match variant {
+                        // Self { field: value }
+                        VariantData::Struct { .. } => cx.expr_struct_ident(
+                            span,
+                            self_kw,
+                            thin_vec![cx.field_imm(
+                                span,
+                                field.ident.unwrap(),
+                                cx.expr_ident(span, Ident::new(sym::value, span))
+                            )],
+                        ),
+                        // Self(value)
+                        VariantData::Tuple(_, _) => cx.expr_call_ident(
+                            span,
+                            self_kw,
+                            thin_vec![cx.expr_ident(span, Ident::new(sym::value, span))],
+                        ),
+                        variant => {
+                            cx.dcx().bug(format!("Invalid derive(From) ADT variant: {variant:?}"));
+                        }
+                    },
+                    _ => cx.dcx().bug("Invalid derive(From) ADT input"),
+                };
+                BlockOrExpr::new_expr(expr)
+            })),
+        }],
+        associated_types: Vec::new(),
+        is_const,
+        is_staged_api_crate: cx.ecfg.features.staged_api(),
+    };
+
+    from_trait_def.expand(cx, mitem, annotatable, push);
+}
diff --git a/compiler/rustc_builtin_macros/src/deriving/generic/ty.rs b/compiler/rustc_builtin_macros/src/deriving/generic/ty.rs
index 00e70b21cf4..1458553d492 100644
--- a/compiler/rustc_builtin_macros/src/deriving/generic/ty.rs
+++ b/compiler/rustc_builtin_macros/src/deriving/generic/ty.rs
@@ -2,7 +2,7 @@
 //! when specifying impls to be derived.
 
 pub(crate) use Ty::*;
-use rustc_ast::{self as ast, Expr, GenericArg, GenericParamKind, Generics, SelfKind};
+use rustc_ast::{self as ast, Expr, GenericArg, GenericParamKind, Generics, SelfKind, TyKind};
 use rustc_expand::base::ExtCtxt;
 use rustc_span::source_map::respan;
 use rustc_span::{DUMMY_SP, Ident, Span, Symbol, kw};
@@ -65,7 +65,7 @@ impl Path {
     }
 }
 
-/// A type. Supports pointers, Self, and literals.
+/// A type. Supports pointers, Self, literals, unit or an arbitrary AST path.
 #[derive(Clone)]
 pub(crate) enum Ty {
     Self_,
@@ -76,6 +76,8 @@ pub(crate) enum Ty {
     Path(Path),
     /// For () return types.
     Unit,
+    /// An arbitrary type.
+    AstTy(Box<ast::Ty>),
 }
 
 pub(crate) fn self_ref() -> Ty {
@@ -101,6 +103,7 @@ impl Ty {
                 let ty = ast::TyKind::Tup(ThinVec::new());
                 cx.ty(span, ty)
             }
+            AstTy(ty) => ty.clone(),
         }
     }
 
@@ -132,6 +135,10 @@ impl Ty {
                 cx.path_all(span, false, vec![self_ty], params)
             }
             Path(p) => p.to_path(cx, span, self_ty, generics),
+            AstTy(ty) => match &ty.kind {
+                TyKind::Path(_, path) => path.clone(),
+                _ => cx.dcx().span_bug(span, "non-path in a path in generic `derive`"),
+            },
             Ref(..) => cx.dcx().span_bug(span, "ref in a path in generic `derive`"),
             Unit => cx.dcx().span_bug(span, "unit in a path in generic `derive`"),
         }
diff --git a/compiler/rustc_builtin_macros/src/deriving/mod.rs b/compiler/rustc_builtin_macros/src/deriving/mod.rs
index 1edc2965def..cee6952fa34 100644
--- a/compiler/rustc_builtin_macros/src/deriving/mod.rs
+++ b/compiler/rustc_builtin_macros/src/deriving/mod.rs
@@ -23,6 +23,7 @@ pub(crate) mod clone;
 pub(crate) mod coerce_pointee;
 pub(crate) mod debug;
 pub(crate) mod default;
+pub(crate) mod from;
 pub(crate) mod hash;
 
 #[path = "cmp/eq.rs"]
diff --git a/compiler/rustc_builtin_macros/src/errors.rs b/compiler/rustc_builtin_macros/src/errors.rs
index 6bcf4d3e0a2..54e8f750337 100644
--- a/compiler/rustc_builtin_macros/src/errors.rs
+++ b/compiler/rustc_builtin_macros/src/errors.rs
@@ -447,6 +447,24 @@ pub(crate) struct DefaultHasArg {
 }
 
 #[derive(Diagnostic)]
+#[diag(builtin_macros_derive_from_wrong_target)]
+#[note(builtin_macros_derive_from_usage_note)]
+pub(crate) struct DeriveFromWrongTarget<'a> {
+    #[primary_span]
+    pub(crate) span: MultiSpan,
+    pub(crate) kind: &'a str,
+}
+
+#[derive(Diagnostic)]
+#[diag(builtin_macros_derive_from_wrong_field_count)]
+#[note(builtin_macros_derive_from_usage_note)]
+pub(crate) struct DeriveFromWrongFieldCount {
+    #[primary_span]
+    pub(crate) span: MultiSpan,
+    pub(crate) multiple_fields: bool,
+}
+
+#[derive(Diagnostic)]
 #[diag(builtin_macros_derive_macro_call)]
 pub(crate) struct DeriveMacroCall {
     #[primary_span]
@@ -906,14 +924,6 @@ pub(crate) struct TakesNoArguments<'a> {
 }
 
 #[derive(Diagnostic)]
-#[diag(builtin_macros_proc_macro_attribute_only_be_used_on_bare_functions)]
-pub(crate) struct AttributeOnlyBeUsedOnBareFunctions<'a> {
-    #[primary_span]
-    pub span: Span,
-    pub path: &'a str,
-}
-
-#[derive(Diagnostic)]
 #[diag(builtin_macros_proc_macro_attribute_only_usable_with_crate_type)]
 pub(crate) struct AttributeOnlyUsableWithCrateType<'a> {
     #[primary_span]
diff --git a/compiler/rustc_builtin_macros/src/format.rs b/compiler/rustc_builtin_macros/src/format.rs
index ec613b7b710..6415e55e0b0 100644
--- a/compiler/rustc_builtin_macros/src/format.rs
+++ b/compiler/rustc_builtin_macros/src/format.rs
@@ -10,11 +10,12 @@ use rustc_ast::{
 };
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::{
-    Applicability, Diag, MultiSpan, PResult, SingleLabelManySpans, listify, pluralize,
+    Applicability, BufferedEarlyLint, Diag, MultiSpan, PResult, SingleLabelManySpans, listify,
+    pluralize,
 };
 use rustc_expand::base::*;
 use rustc_lint_defs::builtin::NAMED_ARGUMENTS_USED_POSITIONALLY;
-use rustc_lint_defs::{BufferedEarlyLint, BuiltinLintDiag, LintId};
+use rustc_lint_defs::{BuiltinLintDiag, LintId};
 use rustc_parse::exp;
 use rustc_parse_format as parse;
 use rustc_span::{BytePos, ErrorGuaranteed, Ident, InnerSpan, Span, Symbol};
@@ -595,7 +596,8 @@ fn make_format_args(
                     named_arg_sp: arg_name.span,
                     named_arg_name: arg_name.name.to_string(),
                     is_formatting_arg: matches!(used_as, Width | Precision),
-                },
+                }
+                .into(),
             });
         }
     }
diff --git a/compiler/rustc_builtin_macros/src/format_foreign.rs b/compiler/rustc_builtin_macros/src/format_foreign.rs
index 3e5a26c0556..cf563a53973 100644
--- a/compiler/rustc_builtin_macros/src/format_foreign.rs
+++ b/compiler/rustc_builtin_macros/src/format_foreign.rs
@@ -416,7 +416,7 @@ pub(crate) mod printf {
                         // Yes, this *is* the parameter.
                         Some(('$', end2)) => {
                             state = Flags;
-                            parameter = Some(at.slice_between(end).unwrap().parse().unwrap());
+                            parameter = at.slice_between(end).unwrap().parse().ok();
                             move_to!(end2);
                         }
                         // Wait, no, actually, it's the width.
diff --git a/compiler/rustc_builtin_macros/src/lib.rs b/compiler/rustc_builtin_macros/src/lib.rs
index 7bc448a9acb..1bcea95fbb7 100644
--- a/compiler/rustc_builtin_macros/src/lib.rs
+++ b/compiler/rustc_builtin_macros/src/lib.rs
@@ -8,7 +8,6 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
 #![feature(assert_matches)]
-#![feature(autodiff)]
 #![feature(box_patterns)]
 #![feature(decl_macro)]
 #![feature(if_let_guard)]
@@ -139,6 +138,7 @@ pub fn register_builtin_macros(resolver: &mut dyn ResolverExpand) {
         PartialEq: partial_eq::expand_deriving_partial_eq,
         PartialOrd: partial_ord::expand_deriving_partial_ord,
         CoercePointee: coerce_pointee::expand_deriving_coerce_pointee,
+        From: from::expand_deriving_from,
     }
 
     let client = rustc_proc_macro::bridge::client::Client::expand1(rustc_proc_macro::quote);
diff --git a/compiler/rustc_builtin_macros/src/proc_macro_harness.rs b/compiler/rustc_builtin_macros/src/proc_macro_harness.rs
index f440adf6cf0..6ac3e17503d 100644
--- a/compiler/rustc_builtin_macros/src/proc_macro_harness.rs
+++ b/compiler/rustc_builtin_macros/src/proc_macro_harness.rs
@@ -231,12 +231,7 @@ impl<'a> Visitor<'a> for CollectProcMacros<'a> {
         let fn_ident = if let ast::ItemKind::Fn(fn_) = &item.kind {
             fn_.ident
         } else {
-            self.dcx
-                .create_err(errors::AttributeOnlyBeUsedOnBareFunctions {
-                    span: attr.span,
-                    path: &pprust::path_to_string(&attr.get_normal_item().path),
-                })
-                .emit();
+            // Error handled by general target checking logic
             return;
         };
 
diff --git a/compiler/rustc_builtin_macros/src/test_harness.rs b/compiler/rustc_builtin_macros/src/test_harness.rs
index e803f3be82b..a9d91f77560 100644
--- a/compiler/rustc_builtin_macros/src/test_harness.rs
+++ b/compiler/rustc_builtin_macros/src/test_harness.rs
@@ -141,7 +141,7 @@ impl<'a> MutVisitor for TestHarnessGenerator<'a> {
         if let ast::ItemKind::Mod(
             _,
             _,
-            ModKind::Loaded(.., ast::ModSpans { inner_span: span, .. }, _),
+            ModKind::Loaded(.., ast::ModSpans { inner_span: span, .. }),
         ) = item.kind
         {
             let prev_tests = mem::take(&mut self.tests);
diff --git a/compiler/rustc_builtin_macros/src/util.rs b/compiler/rustc_builtin_macros/src/util.rs
index f00c170e485..3a4585d5be9 100644
--- a/compiler/rustc_builtin_macros/src/util.rs
+++ b/compiler/rustc_builtin_macros/src/util.rs
@@ -1,12 +1,13 @@
 use rustc_ast::tokenstream::TokenStream;
 use rustc_ast::{self as ast, AttrStyle, Attribute, MetaItem, attr, token};
+use rustc_attr_parsing::validate_attr;
 use rustc_errors::{Applicability, Diag, ErrorGuaranteed};
 use rustc_expand::base::{Annotatable, ExpandResult, ExtCtxt};
 use rustc_expand::expand::AstFragment;
 use rustc_feature::AttributeTemplate;
 use rustc_lint_defs::BuiltinLintDiag;
 use rustc_lint_defs::builtin::DUPLICATE_MACRO_ATTRIBUTES;
-use rustc_parse::{exp, parser, validate_attr};
+use rustc_parse::{exp, parser};
 use rustc_session::errors::report_lit_error;
 use rustc_span::{BytePos, Span, Symbol};
 
diff --git a/compiler/rustc_codegen_cranelift/src/constant.rs b/compiler/rustc_codegen_cranelift/src/constant.rs
index bec546badc9..a56466750e7 100644
--- a/compiler/rustc_codegen_cranelift/src/constant.rs
+++ b/compiler/rustc_codegen_cranelift/src/constant.rs
@@ -281,8 +281,8 @@ fn data_id_for_static(
             .abi
             .bytes();
 
-        let linkage = if import_linkage == rustc_middle::mir::mono::Linkage::ExternalWeak
-            || import_linkage == rustc_middle::mir::mono::Linkage::WeakAny
+        let linkage = if import_linkage == rustc_hir::attrs::Linkage::ExternalWeak
+            || import_linkage == rustc_hir::attrs::Linkage::WeakAny
         {
             Linkage::Preemptible
         } else {
@@ -332,8 +332,8 @@ fn data_id_for_static(
 
     let linkage = if definition {
         crate::linkage::get_static_linkage(tcx, def_id)
-    } else if attrs.linkage == Some(rustc_middle::mir::mono::Linkage::ExternalWeak)
-        || attrs.linkage == Some(rustc_middle::mir::mono::Linkage::WeakAny)
+    } else if attrs.linkage == Some(rustc_hir::attrs::Linkage::ExternalWeak)
+        || attrs.linkage == Some(rustc_hir::attrs::Linkage::WeakAny)
     {
         Linkage::Preemptible
     } else {
diff --git a/compiler/rustc_codegen_cranelift/src/driver/aot.rs b/compiler/rustc_codegen_cranelift/src/driver/aot.rs
index 8ec3599b63d..7e77781dc2f 100644
--- a/compiler/rustc_codegen_cranelift/src/driver/aot.rs
+++ b/compiler/rustc_codegen_cranelift/src/driver/aot.rs
@@ -18,12 +18,11 @@ use rustc_codegen_ssa::{
 use rustc_data_structures::profiling::SelfProfilerRef;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::{IntoDynSyncSend, par_map};
+use rustc_hir::attrs::Linkage as RLinkage;
 use rustc_metadata::fs::copy_to_stdout;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
-use rustc_middle::mir::mono::{
-    CodegenUnit, Linkage as RLinkage, MonoItem, MonoItemData, Visibility,
-};
+use rustc_middle::mir::mono::{CodegenUnit, MonoItem, MonoItemData, Visibility};
 use rustc_session::Session;
 use rustc_session::config::{DebugInfo, OutFileName, OutputFilenames, OutputType};
 
diff --git a/compiler/rustc_codegen_cranelift/src/linkage.rs b/compiler/rustc_codegen_cranelift/src/linkage.rs
index ca853aac158..d76ab9d0109 100644
--- a/compiler/rustc_codegen_cranelift/src/linkage.rs
+++ b/compiler/rustc_codegen_cranelift/src/linkage.rs
@@ -1,4 +1,5 @@
-use rustc_middle::mir::mono::{Linkage as RLinkage, MonoItem, Visibility};
+use rustc_hir::attrs::Linkage as RLinkage;
+use rustc_middle::mir::mono::{MonoItem, Visibility};
 
 use crate::prelude::*;
 
diff --git a/compiler/rustc_codegen_gcc/.github/workflows/m68k.yml b/compiler/rustc_codegen_gcc/.github/workflows/m68k.yml
index 759d0d59e26..e49c62d6c93 100644
--- a/compiler/rustc_codegen_gcc/.github/workflows/m68k.yml
+++ b/compiler/rustc_codegen_gcc/.github/workflows/m68k.yml
@@ -82,20 +82,16 @@ jobs:
     - name: Build sample project with target defined as JSON spec
       run: |
         ./y.sh prepare --only-libcore --cross
-        ./y.sh build --sysroot --features compiler-builtins-no-f16-f128 --target-triple m68k-unknown-linux-gnu --target ${{ github.workspace }}/target_specs/m68k-unknown-linux-gnu.json
+        ./y.sh build --sysroot --target-triple m68k-unknown-linux-gnu --target ${{ github.workspace }}/target_specs/m68k-unknown-linux-gnu.json
         CG_RUSTFLAGS="-Clinker=m68k-unknown-linux-gnu-gcc" ./y.sh cargo build --manifest-path=./tests/hello-world/Cargo.toml --target ${{ github.workspace }}/target_specs/m68k-unknown-linux-gnu.json
         ./y.sh clean all
 
     - name: Build
       run: |
         ./y.sh prepare --only-libcore --cross
-        ./y.sh build --sysroot --features compiler-builtins-no-f16-f128 --target-triple m68k-unknown-linux-gnu
+        ./y.sh build --sysroot --target-triple m68k-unknown-linux-gnu
         ./y.sh test --mini-tests --target-triple m68k-unknown-linux-gnu
-        # FIXME: since https://github.com/rust-lang/rust/pull/140809, we cannot run programs for architectures not
-        # supported by the object crate, since this adds a dependency on symbols.o for the panic runtime.
-        # And as such, a wrong order of the object files in the linker command now fails with an undefined reference
-        # to some symbols like __rustc::rust_panic.
-        #CG_GCC_TEST_TARGET=m68k-unknown-linux-gnu ./y.sh test --cargo-tests --target-triple m68k-unknown-linux-gnu
+        CG_GCC_TEST_TARGET=m68k-unknown-linux-gnu ./y.sh test --cargo-tests --target-triple m68k-unknown-linux-gnu
         ./y.sh clean all
 
     - name: Prepare dependencies
@@ -104,23 +100,21 @@ jobs:
         git config --global user.name "User"
         ./y.sh prepare --cross
 
-    # FIXME: We cannot run programs for architectures not supported by the object crate. See comment above.
-    #- name: Run tests
-      #run: |
-        #./y.sh test --target-triple m68k-unknown-linux-gnu --release --clean --build-sysroot --sysroot-features compiler-builtins-no-f16-f128 ${{ matrix.commands }}
-
-    # FIXME: We cannot run programs for architectures not supported by the object crate. See comment above.
-    #- name: Run Hello World!
-      #run: |
-        #./y.sh build --target-triple m68k-unknown-linux-gnu
-
-        #vm_dir=$(pwd)/vm
-        #cd tests/hello-world
-        #CG_RUSTFLAGS="-Clinker=m68k-unknown-linux-gnu-gcc" ../../y.sh cargo build --target m68k-unknown-linux-gnu
-        #sudo cp target/m68k-unknown-linux-gnu/debug/hello_world $vm_dir/home/
-        #sudo chroot $vm_dir qemu-m68k-static /home/hello_world > hello_world_stdout
-        #expected_output="40"
-        #test $(cat hello_world_stdout) == $expected_output || (echo "Output differs. Actual output: $(cat hello_world_stdout)"; exit 1)
+    - name: Run tests
+      run: |
+        ./y.sh test --target-triple m68k-unknown-linux-gnu --release --clean --build-sysroot ${{ matrix.commands }}
+
+    - name: Run Hello World!
+      run: |
+        ./y.sh build --target-triple m68k-unknown-linux-gnu
+
+        vm_dir=$(pwd)/vm
+        cd tests/hello-world
+        CG_RUSTFLAGS="-Clinker=m68k-unknown-linux-gnu-gcc" ../../y.sh cargo build --target m68k-unknown-linux-gnu
+        sudo cp target/m68k-unknown-linux-gnu/debug/hello_world $vm_dir/home/
+        sudo chroot $vm_dir qemu-m68k-static /home/hello_world > hello_world_stdout
+        expected_output="40"
+        test $(cat hello_world_stdout) == $expected_output || (echo "Output differs. Actual output: $(cat hello_world_stdout)"; exit 1)
 
   # Summary job for the merge queue.
   # ALL THE PREVIOUS JOBS NEED TO BE ADDED TO THE `needs` SECTION OF THIS JOB!
diff --git a/compiler/rustc_codegen_gcc/Cargo.lock b/compiler/rustc_codegen_gcc/Cargo.lock
index 7f35c1a80bd..a5b972baf98 100644
--- a/compiler/rustc_codegen_gcc/Cargo.lock
+++ b/compiler/rustc_codegen_gcc/Cargo.lock
@@ -56,18 +56,18 @@ dependencies = [
 
 [[package]]
 name = "gccjit"
-version = "2.7.0"
+version = "2.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ae99a89184220d967dd300139f2d2ae7d52c1a69d632b24aacc57c54625254ce"
+checksum = "4a0e310ef75f396cd11b2443b353d55376656ca92c13cba36f92b7aff346ac1a"
 dependencies = [
  "gccjit_sys",
 ]
 
 [[package]]
 name = "gccjit_sys"
-version = "0.8.0"
+version = "0.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "24edb7bfe2b7b27c6d09ed23eebfcab0b359c8fe978433f902943e6f127a0f1b"
+checksum = "95ed7572b30cd32430294dde6fb70822d58e67c6846a548647e8739776a0125b"
 dependencies = [
  "libc",
 ]
diff --git a/compiler/rustc_codegen_gcc/Cargo.toml b/compiler/rustc_codegen_gcc/Cargo.toml
index 193348d1ef6..6031933bd2d 100644
--- a/compiler/rustc_codegen_gcc/Cargo.toml
+++ b/compiler/rustc_codegen_gcc/Cargo.toml
@@ -24,7 +24,7 @@ default = ["master"]
 [dependencies]
 object = { version = "0.37.0", default-features = false, features = ["std", "read"] }
 tempfile = "3.20"
-gccjit = "2.7"
+gccjit = "2.8"
 #gccjit = { git = "https://github.com/rust-lang/gccjit.rs" }
 
 # Local copy.
diff --git a/compiler/rustc_codegen_gcc/build_system/src/fmt.rs b/compiler/rustc_codegen_gcc/build_system/src/fmt.rs
index 7e6594f50f9..91535f217e3 100644
--- a/compiler/rustc_codegen_gcc/build_system/src/fmt.rs
+++ b/compiler/rustc_codegen_gcc/build_system/src/fmt.rs
@@ -1,7 +1,7 @@
 use std::ffi::OsStr;
 use std::path::Path;
 
-use crate::utils::run_command_with_output;
+use crate::utils::{run_command_with_output, walk_dir};
 
 fn show_usage() {
     println!(
@@ -32,5 +32,31 @@ pub fn run() -> Result<(), String> {
         if check { &[&"cargo", &"fmt", &"--check"] } else { &[&"cargo", &"fmt"] };
 
     run_command_with_output(cmd, Some(Path::new(".")))?;
-    run_command_with_output(cmd, Some(Path::new("build_system")))
+    run_command_with_output(cmd, Some(Path::new("build_system")))?;
+
+    run_rustfmt_recursively("tests/run", check)
+}
+
+fn run_rustfmt_recursively<P>(dir: P, check: bool) -> Result<(), String>
+where
+    P: AsRef<Path>,
+{
+    walk_dir(
+        dir,
+        &mut |dir| run_rustfmt_recursively(dir, check),
+        &mut |file_path| {
+            if file_path.extension().filter(|ext| ext == &OsStr::new("rs")).is_some() {
+                let rustfmt_cmd: &[&dyn AsRef<OsStr>] = if check {
+                    &[&"rustfmt", &"--check", &file_path]
+                } else {
+                    &[&"rustfmt", &file_path]
+                };
+
+                run_command_with_output(rustfmt_cmd, Some(Path::new(".")))
+            } else {
+                Ok(())
+            }
+        },
+        true,
+    )
 }
diff --git a/compiler/rustc_codegen_gcc/build_system/src/test.rs b/compiler/rustc_codegen_gcc/build_system/src/test.rs
index 2c8271c36a9..3dd3fce2eec 100644
--- a/compiler/rustc_codegen_gcc/build_system/src/test.rs
+++ b/compiler/rustc_codegen_gcc/build_system/src/test.rs
@@ -531,7 +531,7 @@ fn setup_rustc(env: &mut Env, args: &TestArg) -> Result<PathBuf, String> {
             r#"change-id = 115898
 
 [rust]
-codegen-backends = []
+codegen-backends = ["gcc"]
 deny-warnings = false
 verbose-tests = true
 
diff --git a/compiler/rustc_codegen_gcc/libgccjit.version b/compiler/rustc_codegen_gcc/libgccjit.version
index f62154968d3..dc9a0012864 100644
--- a/compiler/rustc_codegen_gcc/libgccjit.version
+++ b/compiler/rustc_codegen_gcc/libgccjit.version
@@ -1 +1 @@
-04ce66d8c918de9273bd7101638ad8724edf5e21
+4e995bd73c4490edfe5080ec6014d63aa9abed5f
diff --git a/compiler/rustc_codegen_gcc/rust-toolchain b/compiler/rustc_codegen_gcc/rust-toolchain
index 058e734be5c..04d33dfb116 100644
--- a/compiler/rustc_codegen_gcc/rust-toolchain
+++ b/compiler/rustc_codegen_gcc/rust-toolchain
@@ -1,3 +1,3 @@
 [toolchain]
-channel = "nightly-2025-08-03"
+channel = "nightly-2025-08-25"
 components = ["rust-src", "rustc-dev", "llvm-tools-preview"]
diff --git a/compiler/rustc_codegen_gcc/src/back/lto.rs b/compiler/rustc_codegen_gcc/src/back/lto.rs
index d558dfbc1c4..fcee6b6df62 100644
--- a/compiler/rustc_codegen_gcc/src/back/lto.rs
+++ b/compiler/rustc_codegen_gcc/src/back/lto.rs
@@ -29,7 +29,7 @@ use rustc_codegen_ssa::back::write::{CodegenContext, FatLtoInput};
 use rustc_codegen_ssa::traits::*;
 use rustc_codegen_ssa::{ModuleCodegen, ModuleKind, looks_like_rust_object_file};
 use rustc_data_structures::memmap::Mmap;
-use rustc_errors::{DiagCtxtHandle, FatalError};
+use rustc_errors::DiagCtxtHandle;
 use rustc_middle::bug;
 use rustc_middle::dep_graph::WorkProduct;
 use rustc_session::config::Lto;
@@ -51,12 +51,11 @@ fn prepare_lto(
     cgcx: &CodegenContext<GccCodegenBackend>,
     each_linked_rlib_for_lto: &[PathBuf],
     dcx: DiagCtxtHandle<'_>,
-) -> Result<LtoData, FatalError> {
+) -> LtoData {
     let tmp_path = match tempdir() {
         Ok(tmp_path) => tmp_path,
         Err(error) => {
-            eprintln!("Cannot create temporary directory: {}", error);
-            return Err(FatalError);
+            dcx.fatal(format!("Cannot create temporary directory: {}", error));
         }
     };
 
@@ -91,15 +90,14 @@ fn prepare_lto(
                         upstream_modules.push((module, CString::new(name).unwrap()));
                     }
                     Err(e) => {
-                        dcx.emit_err(e);
-                        return Err(FatalError);
+                        dcx.emit_fatal(e);
                     }
                 }
             }
         }
     }
 
-    Ok(LtoData { upstream_modules, tmp_path })
+    LtoData { upstream_modules, tmp_path }
 }
 
 fn save_as_file(obj: &[u8], path: &Path) -> Result<(), LtoBitcodeFromRlib> {
@@ -114,10 +112,10 @@ pub(crate) fn run_fat(
     cgcx: &CodegenContext<GccCodegenBackend>,
     each_linked_rlib_for_lto: &[PathBuf],
     modules: Vec<FatLtoInput<GccCodegenBackend>>,
-) -> Result<ModuleCodegen<GccContext>, FatalError> {
+) -> ModuleCodegen<GccContext> {
     let dcx = cgcx.create_dcx();
     let dcx = dcx.handle();
-    let lto_data = prepare_lto(cgcx, each_linked_rlib_for_lto, dcx)?;
+    let lto_data = prepare_lto(cgcx, each_linked_rlib_for_lto, dcx);
     /*let symbols_below_threshold =
     lto_data.symbols_below_threshold.iter().map(|c| c.as_ptr()).collect::<Vec<_>>();*/
     fat_lto(
@@ -137,7 +135,7 @@ fn fat_lto(
     mut serialized_modules: Vec<(SerializedModule<ModuleBuffer>, CString)>,
     tmp_path: TempDir,
     //symbols_below_threshold: &[String],
-) -> Result<ModuleCodegen<GccContext>, FatalError> {
+) -> ModuleCodegen<GccContext> {
     let _timer = cgcx.prof.generic_activity("GCC_fat_lto_build_monolithic_module");
     info!("going for a fat lto");
 
@@ -261,7 +259,7 @@ fn fat_lto(
     // of now.
     module.module_llvm.temp_dir = Some(tmp_path);
 
-    Ok(module)
+    module
 }
 
 pub struct ModuleBuffer(PathBuf);
@@ -286,10 +284,10 @@ pub(crate) fn run_thin(
     each_linked_rlib_for_lto: &[PathBuf],
     modules: Vec<(String, ThinBuffer)>,
     cached_modules: Vec<(SerializedModule<ModuleBuffer>, WorkProduct)>,
-) -> Result<(Vec<ThinModule<GccCodegenBackend>>, Vec<WorkProduct>), FatalError> {
+) -> (Vec<ThinModule<GccCodegenBackend>>, Vec<WorkProduct>) {
     let dcx = cgcx.create_dcx();
     let dcx = dcx.handle();
-    let lto_data = prepare_lto(cgcx, each_linked_rlib_for_lto, dcx)?;
+    let lto_data = prepare_lto(cgcx, each_linked_rlib_for_lto, dcx);
     if cgcx.opts.cg.linker_plugin_lto.enabled() {
         unreachable!(
             "We should never reach this case if the LTO step \
@@ -355,7 +353,7 @@ fn thin_lto(
     tmp_path: TempDir,
     cached_modules: Vec<(SerializedModule<ModuleBuffer>, WorkProduct)>,
     //_symbols_below_threshold: &[String],
-) -> Result<(Vec<ThinModule<GccCodegenBackend>>, Vec<WorkProduct>), FatalError> {
+) -> (Vec<ThinModule<GccCodegenBackend>>, Vec<WorkProduct>) {
     let _timer = cgcx.prof.generic_activity("LLVM_thin_lto_global_analysis");
     info!("going for that thin, thin LTO");
 
@@ -518,13 +516,13 @@ fn thin_lto(
     // TODO: save the directory so that it gets deleted later.
     std::mem::forget(tmp_path);
 
-    Ok((opt_jobs, copy_jobs))
+    (opt_jobs, copy_jobs)
 }
 
 pub fn optimize_thin_module(
     thin_module: ThinModule<GccCodegenBackend>,
     _cgcx: &CodegenContext<GccCodegenBackend>,
-) -> Result<ModuleCodegen<GccContext>, FatalError> {
+) -> ModuleCodegen<GccContext> {
     //let dcx = cgcx.create_dcx();
 
     //let module_name = &thin_module.shared.module_names[thin_module.idx];
@@ -634,7 +632,8 @@ pub fn optimize_thin_module(
             save_temp_bitcode(cgcx, &module, "thin-lto-after-pm");
         }
     }*/
-    Ok(module)
+    #[allow(clippy::let_and_return)]
+    module
 }
 
 pub struct ThinBuffer {
diff --git a/compiler/rustc_codegen_gcc/src/back/write.rs b/compiler/rustc_codegen_gcc/src/back/write.rs
index c1231142c65..84bc7016271 100644
--- a/compiler/rustc_codegen_gcc/src/back/write.rs
+++ b/compiler/rustc_codegen_gcc/src/back/write.rs
@@ -6,7 +6,6 @@ use rustc_codegen_ssa::back::write::{BitcodeSection, CodegenContext, EmitObj, Mo
 use rustc_codegen_ssa::{CompiledModule, ModuleCodegen};
 use rustc_fs_util::link_or_copy;
 use rustc_session::config::OutputType;
-use rustc_span::fatal_error::FatalError;
 use rustc_target::spec::SplitDebuginfo;
 
 use crate::base::add_pic_option;
@@ -17,7 +16,7 @@ pub(crate) fn codegen(
     cgcx: &CodegenContext<GccCodegenBackend>,
     module: ModuleCodegen<GccContext>,
     config: &ModuleConfig,
-) -> Result<CompiledModule, FatalError> {
+) -> CompiledModule {
     let dcx = cgcx.create_dcx();
     let dcx = dcx.handle();
 
@@ -246,7 +245,7 @@ pub(crate) fn codegen(
         }
     }
 
-    Ok(module.into_compiled_module(
+    module.into_compiled_module(
         config.emit_obj != EmitObj::None,
         cgcx.target_can_use_split_dwarf && cgcx.split_debuginfo == SplitDebuginfo::Unpacked,
         config.emit_bc,
@@ -254,7 +253,7 @@ pub(crate) fn codegen(
         config.emit_ir,
         &cgcx.output_filenames,
         cgcx.invocation_temp.as_deref(),
-    ))
+    )
 }
 
 pub(crate) fn save_temp_bitcode(
diff --git a/compiler/rustc_codegen_gcc/src/base.rs b/compiler/rustc_codegen_gcc/src/base.rs
index c105916bbb2..e9d72e457a0 100644
--- a/compiler/rustc_codegen_gcc/src/base.rs
+++ b/compiler/rustc_codegen_gcc/src/base.rs
@@ -8,8 +8,8 @@ use rustc_codegen_ssa::ModuleCodegen;
 use rustc_codegen_ssa::base::maybe_create_entry_wrapper;
 use rustc_codegen_ssa::mono_item::MonoItemExt;
 use rustc_codegen_ssa::traits::DebugInfoCodegenMethods;
+use rustc_hir::attrs::Linkage;
 use rustc_middle::dep_graph;
-use rustc_middle::mir::mono::Linkage;
 #[cfg(feature = "master")]
 use rustc_middle::mir::mono::Visibility;
 use rustc_middle::ty::TyCtxt;
diff --git a/compiler/rustc_codegen_gcc/src/consts.rs b/compiler/rustc_codegen_gcc/src/consts.rs
index 873f1f1951c..619277eba8b 100644
--- a/compiler/rustc_codegen_gcc/src/consts.rs
+++ b/compiler/rustc_codegen_gcc/src/consts.rs
@@ -5,13 +5,13 @@ use rustc_abi::{self as abi, Align, HasDataLayout, Primitive, Size, WrappingRang
 use rustc_codegen_ssa::traits::{
     BaseTypeCodegenMethods, ConstCodegenMethods, StaticCodegenMethods,
 };
+use rustc_hir::attrs::Linkage;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::LOCAL_CRATE;
 use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
 use rustc_middle::mir::interpret::{
     self, ConstAllocation, ErrorHandled, Scalar as InterpScalar, read_target_uint,
 };
-use rustc_middle::mir::mono::Linkage;
 use rustc_middle::ty::layout::LayoutOf;
 use rustc_middle::ty::{self, Instance};
 use rustc_middle::{bug, span_bug};
diff --git a/compiler/rustc_codegen_gcc/src/intrinsic/simd.rs b/compiler/rustc_codegen_gcc/src/intrinsic/simd.rs
index fdc15d580ef..41363d6313d 100644
--- a/compiler/rustc_codegen_gcc/src/intrinsic/simd.rs
+++ b/compiler/rustc_codegen_gcc/src/intrinsic/simd.rs
@@ -1497,7 +1497,6 @@ fn simd_funnel_shift<'a, 'gcc, 'tcx>(
         let index = bx.context.new_rvalue_from_int(bx.int_type, i as i32);
         let a_val = bx.context.new_vector_access(None, a, index).to_rvalue();
         let a_val = bx.context.new_bitcast(None, a_val, unsigned_type);
-        // TODO: we probably need to use gcc_int_cast instead.
         let a_val = bx.gcc_int_cast(a_val, new_int_type);
         let b_val = bx.context.new_vector_access(None, b, index).to_rvalue();
         let b_val = bx.context.new_bitcast(None, b_val, unsigned_type);
diff --git a/compiler/rustc_codegen_gcc/src/lib.rs b/compiler/rustc_codegen_gcc/src/lib.rs
index b11f11d38e3..2d7df79ba95 100644
--- a/compiler/rustc_codegen_gcc/src/lib.rs
+++ b/compiler/rustc_codegen_gcc/src/lib.rs
@@ -93,7 +93,6 @@ use gccjit::{CType, Context, OptimizationLevel};
 #[cfg(feature = "master")]
 use gccjit::{TargetInfo, Version};
 use rustc_ast::expand::allocator::AllocatorKind;
-use rustc_ast::expand::autodiff_attrs::AutoDiffItem;
 use rustc_codegen_ssa::back::lto::{SerializedModule, ThinModule};
 use rustc_codegen_ssa::back::write::{
     CodegenContext, FatLtoInput, ModuleConfig, TargetMachineFactoryFn,
@@ -111,7 +110,6 @@ use rustc_middle::util::Providers;
 use rustc_session::Session;
 use rustc_session::config::{OptLevel, OutputFilenames};
 use rustc_span::Symbol;
-use rustc_span::fatal_error::FatalError;
 use rustc_target::spec::RelocModel;
 use tempfile::TempDir;
 
@@ -363,12 +361,7 @@ impl WriteBackendMethods for GccCodegenBackend {
         _exported_symbols_for_lto: &[String],
         each_linked_rlib_for_lto: &[PathBuf],
         modules: Vec<FatLtoInput<Self>>,
-        diff_functions: Vec<AutoDiffItem>,
-    ) -> Result<ModuleCodegen<Self::Module>, FatalError> {
-        if !diff_functions.is_empty() {
-            unimplemented!();
-        }
-
+    ) -> ModuleCodegen<Self::Module> {
         back::lto::run_fat(cgcx, each_linked_rlib_for_lto, modules)
     }
 
@@ -379,7 +372,7 @@ impl WriteBackendMethods for GccCodegenBackend {
         each_linked_rlib_for_lto: &[PathBuf],
         modules: Vec<(String, Self::ThinBuffer)>,
         cached_modules: Vec<(SerializedModule<Self::ModuleBuffer>, WorkProduct)>,
-    ) -> Result<(Vec<ThinModule<Self>>, Vec<WorkProduct>), FatalError> {
+    ) -> (Vec<ThinModule<Self>>, Vec<WorkProduct>) {
         back::lto::run_thin(cgcx, each_linked_rlib_for_lto, modules, cached_modules)
     }
 
@@ -396,15 +389,14 @@ impl WriteBackendMethods for GccCodegenBackend {
         _dcx: DiagCtxtHandle<'_>,
         module: &mut ModuleCodegen<Self::Module>,
         config: &ModuleConfig,
-    ) -> Result<(), FatalError> {
+    ) {
         module.module_llvm.context.set_optimization_level(to_gcc_opt_level(config.opt_level));
-        Ok(())
     }
 
     fn optimize_thin(
         cgcx: &CodegenContext<Self>,
         thin: ThinModule<Self>,
-    ) -> Result<ModuleCodegen<Self::Module>, FatalError> {
+    ) -> ModuleCodegen<Self::Module> {
         back::lto::optimize_thin_module(thin, cgcx)
     }
 
@@ -412,7 +404,7 @@ impl WriteBackendMethods for GccCodegenBackend {
         cgcx: &CodegenContext<Self>,
         module: ModuleCodegen<Self::Module>,
         config: &ModuleConfig,
-    ) -> Result<CompiledModule, FatalError> {
+    ) -> CompiledModule {
         back::write::codegen(cgcx, module, config)
     }
 
diff --git a/compiler/rustc_codegen_gcc/src/mono_item.rs b/compiler/rustc_codegen_gcc/src/mono_item.rs
index ff188c437da..35d44d21bcb 100644
--- a/compiler/rustc_codegen_gcc/src/mono_item.rs
+++ b/compiler/rustc_codegen_gcc/src/mono_item.rs
@@ -1,11 +1,12 @@
 #[cfg(feature = "master")]
 use gccjit::{FnAttribute, VarAttribute};
 use rustc_codegen_ssa::traits::PreDefineCodegenMethods;
+use rustc_hir::attrs::Linkage;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
 use rustc_middle::bug;
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
-use rustc_middle::mir::mono::{Linkage, Visibility};
+use rustc_middle::mir::mono::Visibility;
 use rustc_middle::ty::layout::{FnAbiOf, HasTypingEnv, LayoutOf};
 use rustc_middle::ty::{self, Instance, TypeVisitableExt};
 
diff --git a/compiler/rustc_codegen_gcc/tests/failing-run-make-tests.txt b/compiler/rustc_codegen_gcc/tests/failing-run-make-tests.txt
index 29032b321fa..c5e22970c66 100644
--- a/compiler/rustc_codegen_gcc/tests/failing-run-make-tests.txt
+++ b/compiler/rustc_codegen_gcc/tests/failing-run-make-tests.txt
@@ -6,7 +6,6 @@ tests/run-make/doctests-keep-binaries/
 tests/run-make/doctests-runtool/
 tests/run-make/emit-shared-files/
 tests/run-make/exit-code/
-tests/run-make/issue-64153/
 tests/run-make/llvm-ident/
 tests/run-make/native-link-modifier-bundle/
 tests/run-make/remap-path-prefix-dwarf/
@@ -34,8 +33,6 @@ tests/run-make/c-link-to-rust-staticlib/
 tests/run-make/foreign-double-unwind/
 tests/run-make/foreign-exceptions/
 tests/run-make/glibc-staticlib-args/
-tests/run-make/issue-36710/
-tests/run-make/issue-68794-textrel-on-minimal-lib/
 tests/run-make/lto-smoke-c/
 tests/run-make/return-non-c-like-enum/
 
diff --git a/compiler/rustc_codegen_gcc/tests/failing-ui-tests.txt b/compiler/rustc_codegen_gcc/tests/failing-ui-tests.txt
index 41fb4729c07..e2615bce190 100644
--- a/compiler/rustc_codegen_gcc/tests/failing-ui-tests.txt
+++ b/compiler/rustc_codegen_gcc/tests/failing-ui-tests.txt
@@ -20,7 +20,7 @@ tests/ui/drop/dynamic-drop.rs
 tests/ui/rfcs/rfc-2091-track-caller/std-panic-locations.rs
 tests/ui/simd/issue-17170.rs
 tests/ui/simd/issue-39720.rs
-tests/ui/issues/issue-14875.rs
+tests/ui/drop/panic-during-drop-14875.rs
 tests/ui/issues/issue-29948.rs
 tests/ui/process/println-with-broken-pipe.rs
 tests/ui/lto/thin-lto-inlines2.rs
@@ -86,3 +86,5 @@ tests/ui/panics/unwind-force-no-unwind-tables.rs
 tests/ui/attributes/fn-align-dyn.rs
 tests/ui/linkage-attr/raw-dylib/elf/glibc-x86_64.rs
 tests/ui/explicit-tail-calls/recursion-etc.rs
+tests/ui/explicit-tail-calls/indexer.rs
+tests/ui/explicit-tail-calls/drop-order.rs
diff --git a/compiler/rustc_codegen_gcc/tests/run/int.rs b/compiler/rustc_codegen_gcc/tests/run/int.rs
index e20ecc23679..78675acb544 100644
--- a/compiler/rustc_codegen_gcc/tests/run/int.rs
+++ b/compiler/rustc_codegen_gcc/tests/run/int.rs
@@ -7,12 +7,10 @@ fn main() {
     use std::hint::black_box;
 
     macro_rules! check {
-        ($ty:ty, $expr:expr) => {
-            {
-                const EXPECTED: $ty = $expr;
-                assert_eq!($expr, EXPECTED);
-            }
-        };
+        ($ty:ty, $expr:expr) => {{
+            const EXPECTED: $ty = $expr;
+            assert_eq!($expr, EXPECTED);
+        }};
     }
 
     check!(u32, (2220326408_u32 + black_box(1)) >> (32 - 6));
diff --git a/compiler/rustc_codegen_gcc/tests/run/int_overflow.rs b/compiler/rustc_codegen_gcc/tests/run/int_overflow.rs
index 78872159f62..78e1cac57e0 100644
--- a/compiler/rustc_codegen_gcc/tests/run/int_overflow.rs
+++ b/compiler/rustc_codegen_gcc/tests/run/int_overflow.rs
@@ -12,7 +12,7 @@ fn main() {
 
     let arg_count = std::env::args().count();
     let int = isize::MAX;
-    let _int = int + arg_count as isize;  // overflow
+    let _int = int + arg_count as isize; // overflow
 
     // If overflow checking is disabled, we should reach here.
     #[cfg(not(debug_assertions))]
diff --git a/compiler/rustc_codegen_gcc/tests/run/structs.rs b/compiler/rustc_codegen_gcc/tests/run/structs.rs
index da73cbed9ae..e08e67837be 100644
--- a/compiler/rustc_codegen_gcc/tests/run/structs.rs
+++ b/compiler/rustc_codegen_gcc/tests/run/structs.rs
@@ -27,12 +27,8 @@ fn one() -> isize {
 
 #[no_mangle]
 extern "C" fn main(argc: i32, _argv: *const *const u8) -> i32 {
-    let test = Test {
-        field: one(),
-    };
-    let two = Two {
-        two: 2,
-    };
+    let test = Test { field: one() };
+    let two = Two { two: 2 };
     unsafe {
         libc::printf(b"%ld\n\0" as *const u8 as *const i8, test.field);
         libc::printf(b"%ld\n\0" as *const u8 as *const i8, two.two);
diff --git a/compiler/rustc_codegen_gcc/tests/run/volatile.rs b/compiler/rustc_codegen_gcc/tests/run/volatile.rs
index 94a7bdc5c06..dc11fbfa600 100644
--- a/compiler/rustc_codegen_gcc/tests/run/volatile.rs
+++ b/compiler/rustc_codegen_gcc/tests/run/volatile.rs
@@ -12,15 +12,11 @@ struct Struct {
     func: unsafe fn(*const ()),
 }
 
-fn func(_ptr: *const ()) {
-}
+fn func(_ptr: *const ()) {}
 
 fn main() {
     let mut x = MaybeUninit::<&Struct>::uninit();
-    x.write(&Struct {
-        pointer: std::ptr::null(),
-        func,
-    });
+    x.write(&Struct { pointer: std::ptr::null(), func });
     let x = unsafe { x.assume_init() };
     let value = unsafe { (x as *const Struct).read_volatile() };
     println!("{:?}", value);
diff --git a/compiler/rustc_codegen_gcc/tests/run/volatile2.rs b/compiler/rustc_codegen_gcc/tests/run/volatile2.rs
index bdcb8259878..ada112687d3 100644
--- a/compiler/rustc_codegen_gcc/tests/run/volatile2.rs
+++ b/compiler/rustc_codegen_gcc/tests/run/volatile2.rs
@@ -7,7 +7,14 @@ mod libc {
     #[link(name = "c")]
     extern "C" {
         pub fn sigaction(signum: i32, act: *const sigaction, oldact: *mut sigaction) -> i32;
-        pub fn mmap(addr: *mut (), len: usize, prot: i32, flags: i32, fd: i32, offset: i64) -> *mut ();
+        pub fn mmap(
+            addr: *mut (),
+            len: usize,
+            prot: i32,
+            flags: i32,
+            fd: i32,
+            offset: i64,
+        ) -> *mut ();
         pub fn mprotect(addr: *mut (), len: usize, prot: i32) -> i32;
     }
 
@@ -54,7 +61,8 @@ fn main() {
             libc::MAP_PRIVATE | libc::MAP_ANONYMOUS,
             -1,
             0,
-        ).cast();
+        )
+        .cast();
         if STORAGE == libc::MAP_FAILED {
             panic!("error: mmap failed");
         }
diff --git a/compiler/rustc_codegen_llvm/Cargo.toml b/compiler/rustc_codegen_llvm/Cargo.toml
index 2d11628250c..26d20acbe28 100644
--- a/compiler/rustc_codegen_llvm/Cargo.toml
+++ b/compiler/rustc_codegen_llvm/Cargo.toml
@@ -8,11 +8,11 @@ test = false
 
 [dependencies]
 # tidy-alphabetical-start
-bitflags = "2.4.1"
+bitflags.workspace = true
 # To avoid duplicate dependencies, this should match the version of gimli used
 # by `rustc_codegen_ssa` via its `thorin-dwp` dependency.
 gimli = "0.31"
-itertools = "0.12"
+itertools.workspace = true
 libc = "0.2"
 measureme = "12.0.1"
 object = { version = "0.37.0", default-features = false, features = ["std", "read"] }
@@ -40,7 +40,7 @@ rustc_target = { path = "../rustc_target" }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
 
 [features]
diff --git a/compiler/rustc_codegen_llvm/src/abi.rs b/compiler/rustc_codegen_llvm/src/abi.rs
index 009e7e2487b..ac7583f5666 100644
--- a/compiler/rustc_codegen_llvm/src/abi.rs
+++ b/compiler/rustc_codegen_llvm/src/abi.rs
@@ -24,6 +24,7 @@ use crate::attributes::{self, llfn_attrs_from_instance};
 use crate::builder::Builder;
 use crate::context::CodegenCx;
 use crate::llvm::{self, Attribute, AttributePlace};
+use crate::llvm_util;
 use crate::type_::Type;
 use crate::type_of::LayoutLlvmExt;
 use crate::value::Value;
@@ -41,12 +42,13 @@ trait ArgAttributesExt {
 const ABI_AFFECTING_ATTRIBUTES: [(ArgAttribute, llvm::AttributeKind); 1] =
     [(ArgAttribute::InReg, llvm::AttributeKind::InReg)];
 
-const OPTIMIZATION_ATTRIBUTES: [(ArgAttribute, llvm::AttributeKind); 5] = [
+const OPTIMIZATION_ATTRIBUTES: [(ArgAttribute, llvm::AttributeKind); 6] = [
     (ArgAttribute::NoAlias, llvm::AttributeKind::NoAlias),
-    (ArgAttribute::NoCapture, llvm::AttributeKind::NoCapture),
+    (ArgAttribute::CapturesAddress, llvm::AttributeKind::CapturesAddress),
     (ArgAttribute::NonNull, llvm::AttributeKind::NonNull),
     (ArgAttribute::ReadOnly, llvm::AttributeKind::ReadOnly),
     (ArgAttribute::NoUndef, llvm::AttributeKind::NoUndef),
+    (ArgAttribute::CapturesReadOnly, llvm::AttributeKind::CapturesReadOnly),
 ];
 
 fn get_attrs<'ll>(this: &ArgAttributes, cx: &CodegenCx<'ll, '_>) -> SmallVec<[&'ll Attribute; 8]> {
@@ -82,6 +84,12 @@ fn get_attrs<'ll>(this: &ArgAttributes, cx: &CodegenCx<'ll, '_>) -> SmallVec<[&'
         }
         for (attr, llattr) in OPTIMIZATION_ATTRIBUTES {
             if regular.contains(attr) {
+                // captures(...) is only available since LLVM 21.
+                if (attr == ArgAttribute::CapturesReadOnly || attr == ArgAttribute::CapturesAddress)
+                    && llvm_util::get_version() < (21, 0, 0)
+                {
+                    continue;
+                }
                 attrs.push(llattr.create_attr(cx.llcx));
             }
         }
@@ -500,7 +508,16 @@ impl<'ll, 'tcx> FnAbiLlvmExt<'ll, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
                     }
                 }
                 PassMode::Indirect { attrs, meta_attrs: None, on_stack: false } => {
-                    apply(attrs);
+                    let i = apply(attrs);
+                    if cx.sess().opts.optimize != config::OptLevel::No
+                        && llvm_util::get_version() >= (21, 0, 0)
+                    {
+                        attributes::apply_to_llfn(
+                            llfn,
+                            llvm::AttributePlace::Argument(i),
+                            &[llvm::AttributeKind::DeadOnReturn.create_attr(cx.llcx)],
+                        );
+                    }
                 }
                 PassMode::Indirect { attrs, meta_attrs: Some(meta_attrs), on_stack } => {
                     assert!(!on_stack);
diff --git a/compiler/rustc_codegen_llvm/src/allocator.rs b/compiler/rustc_codegen_llvm/src/allocator.rs
index 2b5090ed6db..df3e49279d9 100644
--- a/compiler/rustc_codegen_llvm/src/allocator.rs
+++ b/compiler/rustc_codegen_llvm/src/allocator.rs
@@ -8,11 +8,12 @@ use rustc_middle::bug;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::config::{DebugInfo, OomStrategy};
 use rustc_symbol_mangling::mangle_internal_symbol;
+use smallvec::SmallVec;
 
 use crate::builder::SBuilder;
 use crate::declare::declare_simple_fn;
-use crate::llvm::{self, False, True, Type, Value};
-use crate::{SimpleCx, attributes, debuginfo};
+use crate::llvm::{self, FALSE, TRUE, Type, Value};
+use crate::{SimpleCx, attributes, debuginfo, llvm_util};
 
 pub(crate) unsafe fn codegen(
     tcx: TyCtxt<'_>,
@@ -79,7 +80,7 @@ pub(crate) unsafe fn codegen(
             &cx,
             &mangle_internal_symbol(tcx, OomStrategy::SYMBOL),
             &i8,
-            &llvm::LLVMConstInt(i8, tcx.sess.opts.unstable_opts.oom.should_panic() as u64, False),
+            &llvm::LLVMConstInt(i8, tcx.sess.opts.unstable_opts.oom.should_panic() as u64, FALSE),
         );
 
         // __rust_no_alloc_shim_is_unstable_v2
@@ -147,6 +148,20 @@ fn create_wrapper_function(
         llvm::Visibility::from_generic(tcx.sess.default_visibility()),
         ty,
     );
+
+    let mut attrs = SmallVec::<[_; 2]>::new();
+
+    let target_cpu = llvm_util::target_cpu(tcx.sess);
+    let target_cpu_attr = llvm::CreateAttrStringValue(cx.llcx, "target-cpu", target_cpu);
+
+    let tune_cpu_attr = llvm_util::tune_cpu(tcx.sess)
+        .map(|tune_cpu| llvm::CreateAttrStringValue(cx.llcx, "tune-cpu", tune_cpu));
+
+    attrs.push(target_cpu_attr);
+    attrs.extend(tune_cpu_attr);
+
+    attributes::apply_to_llfn(llfn, llvm::AttributePlace::Function, &attrs);
+
     let no_return = if no_return {
         // -> ! DIFlagNoReturn
         let no_return = llvm::AttributeKind::NoReturn.create_attr(cx.llcx);
@@ -186,7 +201,7 @@ fn create_wrapper_function(
             .map(|(i, _)| llvm::get_param(llfn, i as c_uint))
             .collect::<Vec<_>>();
         let ret = bx.call(ty, callee, &args, None);
-        llvm::LLVMSetTailCall(ret, True);
+        llvm::LLVMSetTailCall(ret, TRUE);
         if output.is_some() {
             bx.ret(ret);
         } else {
diff --git a/compiler/rustc_codegen_llvm/src/asm.rs b/compiler/rustc_codegen_llvm/src/asm.rs
index a643a91141e..38c1d3b53e8 100644
--- a/compiler/rustc_codegen_llvm/src/asm.rs
+++ b/compiler/rustc_codegen_llvm/src/asm.rs
@@ -16,6 +16,7 @@ use tracing::debug;
 use crate::builder::Builder;
 use crate::common::Funclet;
 use crate::context::CodegenCx;
+use crate::llvm::ToLlvmBool;
 use crate::type_::Type;
 use crate::type_of::LayoutLlvmExt;
 use crate::value::Value;
@@ -470,10 +471,6 @@ pub(crate) fn inline_asm_call<'ll>(
     dest: Option<&'ll llvm::BasicBlock>,
     catch_funclet: Option<(&'ll llvm::BasicBlock, Option<&Funclet<'ll>>)>,
 ) -> Option<&'ll Value> {
-    let volatile = if volatile { llvm::True } else { llvm::False };
-    let alignstack = if alignstack { llvm::True } else { llvm::False };
-    let can_throw = if unwind { llvm::True } else { llvm::False };
-
     let argtys = inputs
         .iter()
         .map(|v| {
@@ -500,10 +497,10 @@ pub(crate) fn inline_asm_call<'ll>(
             asm.len(),
             cons.as_ptr(),
             cons.len(),
-            volatile,
-            alignstack,
+            volatile.to_llvm_bool(),
+            alignstack.to_llvm_bool(),
             dia,
-            can_throw,
+            unwind.to_llvm_bool(),
         )
     };
 
diff --git a/compiler/rustc_codegen_llvm/src/attributes.rs b/compiler/rustc_codegen_llvm/src/attributes.rs
index c548f467583..5affb26483a 100644
--- a/compiler/rustc_codegen_llvm/src/attributes.rs
+++ b/compiler/rustc_codegen_llvm/src/attributes.rs
@@ -28,22 +28,6 @@ pub(crate) fn apply_to_callsite(callsite: &Value, idx: AttributePlace, attrs: &[
     }
 }
 
-pub(crate) fn has_attr(llfn: &Value, idx: AttributePlace, attr: AttributeKind) -> bool {
-    llvm::HasAttributeAtIndex(llfn, idx, attr)
-}
-
-pub(crate) fn has_string_attr(llfn: &Value, name: &str) -> bool {
-    llvm::HasStringAttribute(llfn, name)
-}
-
-pub(crate) fn remove_from_llfn(llfn: &Value, place: AttributePlace, kind: AttributeKind) {
-    llvm::RemoveRustEnumAttributeAtIndex(llfn, place, kind);
-}
-
-pub(crate) fn remove_string_attr_from_llfn(llfn: &Value, name: &str) {
-    llvm::RemoveStringAttrFromFn(llfn, name);
-}
-
 /// Get LLVM attribute for the provided inline heuristic.
 #[inline]
 fn inline_attr<'ll>(cx: &CodegenCx<'ll, '_>, inline: InlineAttr) -> Option<&'ll Attribute> {
@@ -436,6 +420,16 @@ pub(crate) fn llfn_attrs_from_instance<'ll, 'tcx>(
         || codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::ALLOCATOR_ZEROED)
     {
         to_add.push(create_alloc_family_attr(cx.llcx));
+        if let Some(zv) =
+            cx.tcx.get_attr(instance.def_id(), rustc_span::sym::rustc_allocator_zeroed_variant)
+            && let Some(name) = zv.value_str()
+        {
+            to_add.push(llvm::CreateAttrStringValue(
+                cx.llcx,
+                "alloc-variant-zeroed",
+                &mangle_internal_symbol(cx.tcx, name.as_str()),
+            ));
+        }
         // apply to argument place instead of function
         let alloc_align = AttributeKind::AllocAlign.create_attr(cx.llcx);
         attributes::apply_to_llfn(llfn, AttributePlace::Argument(1), &[alloc_align]);
@@ -513,7 +507,7 @@ pub(crate) fn llfn_attrs_from_instance<'ll, 'tcx>(
             to_add.push(llvm::CreateAttrStringValue(cx.llcx, "wasm-import-module", module));
 
             let name =
-                codegen_fn_attrs.link_name.unwrap_or_else(|| cx.tcx.item_name(instance.def_id()));
+                codegen_fn_attrs.symbol_name.unwrap_or_else(|| cx.tcx.item_name(instance.def_id()));
             let name = name.as_str();
             to_add.push(llvm::CreateAttrStringValue(cx.llcx, "wasm-import-name", name));
         }
diff --git a/compiler/rustc_codegen_llvm/src/back/archive.rs b/compiler/rustc_codegen_llvm/src/back/archive.rs
index 0a161442933..7a340ae83f3 100644
--- a/compiler/rustc_codegen_llvm/src/back/archive.rs
+++ b/compiler/rustc_codegen_llvm/src/back/archive.rs
@@ -1,104 +1,21 @@
 //! A helper class for dealing with static archives
 
-use std::ffi::{CStr, CString, c_char, c_void};
-use std::path::{Path, PathBuf};
-use std::{io, mem, ptr, str};
+use std::ffi::{CStr, c_char, c_void};
+use std::io;
 
 use rustc_codegen_ssa::back::archive::{
-    ArArchiveBuilder, ArchiveBuildFailure, ArchiveBuilder, ArchiveBuilderBuilder,
-    DEFAULT_OBJECT_READER, ObjectReader, UnknownArchiveKind, try_extract_macho_fat_archive,
+    ArArchiveBuilder, ArchiveBuilder, ArchiveBuilderBuilder, DEFAULT_OBJECT_READER, ObjectReader,
 };
 use rustc_session::Session;
 
-use crate::llvm::archive_ro::{ArchiveRO, Child};
-use crate::llvm::{self, ArchiveKind, last_error};
-
-/// Helper for adding many files to an archive.
-#[must_use = "must call build() to finish building the archive"]
-pub(crate) struct LlvmArchiveBuilder<'a> {
-    sess: &'a Session,
-    additions: Vec<Addition>,
-}
-
-enum Addition {
-    File { path: PathBuf, name_in_archive: String },
-    Archive { path: PathBuf, archive: ArchiveRO, skip: Box<dyn FnMut(&str) -> bool> },
-}
-
-impl Addition {
-    fn path(&self) -> &Path {
-        match self {
-            Addition::File { path, .. } | Addition::Archive { path, .. } => path,
-        }
-    }
-}
-
-fn is_relevant_child(c: &Child<'_>) -> bool {
-    match c.name() {
-        Some(name) => !name.contains("SYMDEF"),
-        None => false,
-    }
-}
-
-impl<'a> ArchiveBuilder for LlvmArchiveBuilder<'a> {
-    fn add_archive(
-        &mut self,
-        archive: &Path,
-        skip: Box<dyn FnMut(&str) -> bool + 'static>,
-    ) -> io::Result<()> {
-        let mut archive = archive.to_path_buf();
-        if self.sess.target.llvm_target.contains("-apple-macosx") {
-            if let Some(new_archive) = try_extract_macho_fat_archive(self.sess, &archive)? {
-                archive = new_archive
-            }
-        }
-        let archive_ro = match ArchiveRO::open(&archive) {
-            Ok(ar) => ar,
-            Err(e) => return Err(io::Error::new(io::ErrorKind::Other, e)),
-        };
-        if self.additions.iter().any(|ar| ar.path() == archive) {
-            return Ok(());
-        }
-        self.additions.push(Addition::Archive {
-            path: archive,
-            archive: archive_ro,
-            skip: Box::new(skip),
-        });
-        Ok(())
-    }
-
-    /// Adds an arbitrary file to this archive
-    fn add_file(&mut self, file: &Path) {
-        let name = file.file_name().unwrap().to_str().unwrap();
-        self.additions
-            .push(Addition::File { path: file.to_path_buf(), name_in_archive: name.to_owned() });
-    }
-
-    /// Combine the provided files, rlibs, and native libraries into a single
-    /// `Archive`.
-    fn build(mut self: Box<Self>, output: &Path) -> bool {
-        match self.build_with_llvm(output) {
-            Ok(any_members) => any_members,
-            Err(error) => {
-                self.sess.dcx().emit_fatal(ArchiveBuildFailure { path: output.to_owned(), error })
-            }
-        }
-    }
-}
+use crate::llvm;
 
 pub(crate) struct LlvmArchiveBuilderBuilder;
 
 impl ArchiveBuilderBuilder for LlvmArchiveBuilderBuilder {
     fn new_archive_builder<'a>(&self, sess: &'a Session) -> Box<dyn ArchiveBuilder + 'a> {
-        // Keeping LlvmArchiveBuilder around in case of a regression caused by using
-        // ArArchiveBuilder.
-        // FIXME(#128955) remove a couple of months after #128936 gets merged in case
-        // no regression is found.
-        if false {
-            Box::new(LlvmArchiveBuilder { sess, additions: Vec::new() })
-        } else {
-            Box::new(ArArchiveBuilder::new(sess, &LLVM_OBJECT_READER))
-        }
+        // Use the `object` crate to build archives, with a little bit of help from LLVM.
+        Box::new(ArArchiveBuilder::new(sess, &LLVM_OBJECT_READER))
     }
 }
 
@@ -178,91 +95,3 @@ fn llvm_is_64_bit_object_file(buf: &[u8]) -> bool {
 fn llvm_is_ec_object_file(buf: &[u8]) -> bool {
     unsafe { llvm::LLVMRustIsECObject(buf.as_ptr(), buf.len()) }
 }
-
-impl<'a> LlvmArchiveBuilder<'a> {
-    fn build_with_llvm(&mut self, output: &Path) -> io::Result<bool> {
-        let kind = &*self.sess.target.archive_format;
-        let kind = kind
-            .parse::<ArchiveKind>()
-            .map_err(|_| kind)
-            .unwrap_or_else(|kind| self.sess.dcx().emit_fatal(UnknownArchiveKind { kind }));
-
-        let mut additions = mem::take(&mut self.additions);
-        // Values in the `members` list below will contain pointers to the strings allocated here.
-        // So they need to get dropped after all elements of `members` get freed.
-        let mut strings = Vec::new();
-        let mut members = Vec::new();
-
-        let dst = CString::new(output.to_str().unwrap())?;
-
-        unsafe {
-            for addition in &mut additions {
-                match addition {
-                    Addition::File { path, name_in_archive } => {
-                        let path = CString::new(path.to_str().unwrap())?;
-                        let name = CString::new(name_in_archive.as_bytes())?;
-                        members.push(llvm::LLVMRustArchiveMemberNew(
-                            path.as_ptr(),
-                            name.as_ptr(),
-                            None,
-                        ));
-                        strings.push(path);
-                        strings.push(name);
-                    }
-                    Addition::Archive { archive, skip, .. } => {
-                        for child in archive.iter() {
-                            let child = child.map_err(string_to_io_error)?;
-                            if !is_relevant_child(&child) {
-                                continue;
-                            }
-                            let child_name = child.name().unwrap();
-                            if skip(child_name) {
-                                continue;
-                            }
-
-                            // It appears that LLVM's archive writer is a little
-                            // buggy if the name we pass down isn't just the
-                            // filename component, so chop that off here and
-                            // pass it in.
-                            //
-                            // See LLVM bug 25877 for more info.
-                            let child_name =
-                                Path::new(child_name).file_name().unwrap().to_str().unwrap();
-                            let name = CString::new(child_name)?;
-                            let m = llvm::LLVMRustArchiveMemberNew(
-                                ptr::null(),
-                                name.as_ptr(),
-                                Some(child.raw),
-                            );
-                            members.push(m);
-                            strings.push(name);
-                        }
-                    }
-                }
-            }
-
-            let r = llvm::LLVMRustWriteArchive(
-                dst.as_ptr(),
-                members.len() as libc::size_t,
-                members.as_ptr() as *const &_,
-                true,
-                kind,
-                self.sess.target.arch == "arm64ec",
-            );
-            let ret = if r.into_result().is_err() {
-                let msg = last_error().unwrap_or_else(|| "failed to write archive".into());
-                Err(io::Error::new(io::ErrorKind::Other, msg))
-            } else {
-                Ok(!members.is_empty())
-            };
-            for member in members {
-                llvm::LLVMRustArchiveMemberFree(member);
-            }
-            ret
-        }
-    }
-}
-
-fn string_to_io_error(s: String) -> io::Error {
-    io::Error::new(io::ErrorKind::Other, format!("bad archive: {s}"))
-}
diff --git a/compiler/rustc_codegen_llvm/src/back/lto.rs b/compiler/rustc_codegen_llvm/src/back/lto.rs
index c269f11e931..d85f432702c 100644
--- a/compiler/rustc_codegen_llvm/src/back/lto.rs
+++ b/compiler/rustc_codegen_llvm/src/back/lto.rs
@@ -14,7 +14,7 @@ use rustc_codegen_ssa::traits::*;
 use rustc_codegen_ssa::{ModuleCodegen, ModuleKind, looks_like_rust_object_file};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::memmap::Mmap;
-use rustc_errors::{DiagCtxtHandle, FatalError};
+use rustc_errors::DiagCtxtHandle;
 use rustc_middle::bug;
 use rustc_middle::dep_graph::WorkProduct;
 use rustc_session::config::{self, Lto};
@@ -24,9 +24,8 @@ use crate::back::write::{
     self, CodegenDiagnosticsStage, DiagnosticHandlers, bitcode_section_name, save_temp_bitcode,
 };
 use crate::errors::{LlvmError, LtoBitcodeFromRlib};
-use crate::llvm::AttributePlace::Function;
 use crate::llvm::{self, build_string};
-use crate::{LlvmCodegenBackend, ModuleLlvm, SimpleCx, attributes};
+use crate::{LlvmCodegenBackend, ModuleLlvm, SimpleCx};
 
 /// We keep track of the computed LTO cache keys from the previous
 /// session to determine which CGUs we can reuse.
@@ -37,7 +36,7 @@ fn prepare_lto(
     exported_symbols_for_lto: &[String],
     each_linked_rlib_for_lto: &[PathBuf],
     dcx: DiagCtxtHandle<'_>,
-) -> Result<(Vec<CString>, Vec<(SerializedModule<ModuleBuffer>, CString)>), FatalError> {
+) -> (Vec<CString>, Vec<(SerializedModule<ModuleBuffer>, CString)>) {
     let mut symbols_below_threshold = exported_symbols_for_lto
         .iter()
         .map(|symbol| CString::new(symbol.to_owned()).unwrap())
@@ -80,16 +79,13 @@ fn prepare_lto(
                         let module = SerializedModule::FromRlib(data.to_vec());
                         upstream_modules.push((module, CString::new(name).unwrap()));
                     }
-                    Err(e) => {
-                        dcx.emit_err(e);
-                        return Err(FatalError);
-                    }
+                    Err(e) => dcx.emit_fatal(e),
                 }
             }
         }
     }
 
-    Ok((symbols_below_threshold, upstream_modules))
+    (symbols_below_threshold, upstream_modules)
 }
 
 fn get_bitcode_slice_from_object_data<'a>(
@@ -124,11 +120,11 @@ pub(crate) fn run_fat(
     exported_symbols_for_lto: &[String],
     each_linked_rlib_for_lto: &[PathBuf],
     modules: Vec<FatLtoInput<LlvmCodegenBackend>>,
-) -> Result<ModuleCodegen<ModuleLlvm>, FatalError> {
+) -> ModuleCodegen<ModuleLlvm> {
     let dcx = cgcx.create_dcx();
     let dcx = dcx.handle();
     let (symbols_below_threshold, upstream_modules) =
-        prepare_lto(cgcx, exported_symbols_for_lto, each_linked_rlib_for_lto, dcx)?;
+        prepare_lto(cgcx, exported_symbols_for_lto, each_linked_rlib_for_lto, dcx);
     let symbols_below_threshold =
         symbols_below_threshold.iter().map(|c| c.as_ptr()).collect::<Vec<_>>();
     fat_lto(cgcx, dcx, modules, upstream_modules, &symbols_below_threshold)
@@ -143,11 +139,11 @@ pub(crate) fn run_thin(
     each_linked_rlib_for_lto: &[PathBuf],
     modules: Vec<(String, ThinBuffer)>,
     cached_modules: Vec<(SerializedModule<ModuleBuffer>, WorkProduct)>,
-) -> Result<(Vec<ThinModule<LlvmCodegenBackend>>, Vec<WorkProduct>), FatalError> {
+) -> (Vec<ThinModule<LlvmCodegenBackend>>, Vec<WorkProduct>) {
     let dcx = cgcx.create_dcx();
     let dcx = dcx.handle();
     let (symbols_below_threshold, upstream_modules) =
-        prepare_lto(cgcx, exported_symbols_for_lto, each_linked_rlib_for_lto, dcx)?;
+        prepare_lto(cgcx, exported_symbols_for_lto, each_linked_rlib_for_lto, dcx);
     let symbols_below_threshold =
         symbols_below_threshold.iter().map(|c| c.as_ptr()).collect::<Vec<_>>();
     if cgcx.opts.cg.linker_plugin_lto.enabled() {
@@ -174,7 +170,7 @@ fn fat_lto(
     modules: Vec<FatLtoInput<LlvmCodegenBackend>>,
     mut serialized_modules: Vec<(SerializedModule<ModuleBuffer>, CString)>,
     symbols_below_threshold: &[*const libc::c_char],
-) -> Result<ModuleCodegen<ModuleLlvm>, FatalError> {
+) -> ModuleCodegen<ModuleLlvm> {
     let _timer = cgcx.prof.generic_activity("LLVM_fat_lto_build_monolithic_module");
     info!("going for a fat lto");
 
@@ -225,7 +221,7 @@ fn fat_lto(
             assert!(!serialized_modules.is_empty(), "must have at least one serialized module");
             let (buffer, name) = serialized_modules.remove(0);
             info!("no in-memory regular modules to choose from, parsing {:?}", name);
-            let llvm_module = ModuleLlvm::parse(cgcx, &name, buffer.data(), dcx)?;
+            let llvm_module = ModuleLlvm::parse(cgcx, &name, buffer.data(), dcx);
             ModuleCodegen::new_regular(name.into_string().unwrap(), llvm_module)
         }
     };
@@ -266,7 +262,9 @@ fn fat_lto(
                 });
             info!("linking {:?}", name);
             let data = bc_decoded.data();
-            linker.add(data).map_err(|()| write::llvm_err(dcx, LlvmError::LoadBitcode { name }))?;
+            linker
+                .add(data)
+                .unwrap_or_else(|()| write::llvm_err(dcx, LlvmError::LoadBitcode { name }));
         }
         drop(linker);
         save_temp_bitcode(cgcx, &module, "lto.input");
@@ -283,7 +281,7 @@ fn fat_lto(
         save_temp_bitcode(cgcx, &module, "lto.after-restriction");
     }
 
-    Ok(module)
+    module
 }
 
 pub(crate) struct Linker<'a>(&'a mut llvm::Linker<'a>);
@@ -353,7 +351,7 @@ fn thin_lto(
     serialized_modules: Vec<(SerializedModule<ModuleBuffer>, CString)>,
     cached_modules: Vec<(SerializedModule<ModuleBuffer>, WorkProduct)>,
     symbols_below_threshold: &[*const libc::c_char],
-) -> Result<(Vec<ThinModule<LlvmCodegenBackend>>, Vec<WorkProduct>), FatalError> {
+) -> (Vec<ThinModule<LlvmCodegenBackend>>, Vec<WorkProduct>) {
     let _timer = cgcx.prof.generic_activity("LLVM_thin_lto_global_analysis");
     unsafe {
         info!("going for that thin, thin LTO");
@@ -423,7 +421,7 @@ fn thin_lto(
             symbols_below_threshold.as_ptr(),
             symbols_below_threshold.len(),
         )
-        .ok_or_else(|| write::llvm_err(dcx, LlvmError::PrepareThinLtoContext))?;
+        .unwrap_or_else(|| write::llvm_err(dcx, LlvmError::PrepareThinLtoContext));
 
         let data = ThinData(data);
 
@@ -493,10 +491,10 @@ fn thin_lto(
         if let Some(path) = key_map_path
             && let Err(err) = curr_key_map.save_to_file(&path)
         {
-            return Err(write::llvm_err(dcx, LlvmError::WriteThinLtoKey { err }));
+            write::llvm_err(dcx, LlvmError::WriteThinLtoKey { err });
         }
 
-        Ok((opt_jobs, copy_jobs))
+        (opt_jobs, copy_jobs)
     }
 }
 
@@ -551,7 +549,7 @@ pub(crate) fn run_pass_manager(
     dcx: DiagCtxtHandle<'_>,
     module: &mut ModuleCodegen<ModuleLlvm>,
     thin: bool,
-) -> Result<(), FatalError> {
+) {
     let _timer = cgcx.prof.generic_activity_with_arg("LLVM_lto_optimize", &*module.name);
     let config = cgcx.config(module.kind);
 
@@ -583,7 +581,7 @@ pub(crate) fn run_pass_manager(
     }
 
     unsafe {
-        write::llvm_optimize(cgcx, dcx, module, None, config, opt_level, opt_stage, stage)?;
+        write::llvm_optimize(cgcx, dcx, module, None, config, opt_level, opt_stage, stage);
     }
 
     if enable_gpu && !thin {
@@ -593,36 +591,11 @@ pub(crate) fn run_pass_manager(
     }
 
     if cfg!(llvm_enzyme) && enable_ad && !thin {
-        let cx =
-            SimpleCx::new(module.module_llvm.llmod(), &module.module_llvm.llcx, cgcx.pointer_size);
-
-        for function in cx.get_functions() {
-            let enzyme_marker = "enzyme_marker";
-            if attributes::has_string_attr(function, enzyme_marker) {
-                // Sanity check: Ensure 'noinline' is present before replacing it.
-                assert!(
-                    attributes::has_attr(function, Function, llvm::AttributeKind::NoInline),
-                    "Expected __enzyme function to have 'noinline' before adding 'alwaysinline'"
-                );
-
-                attributes::remove_from_llfn(function, Function, llvm::AttributeKind::NoInline);
-                attributes::remove_string_attr_from_llfn(function, enzyme_marker);
-
-                assert!(
-                    !attributes::has_string_attr(function, enzyme_marker),
-                    "Expected function to not have 'enzyme_marker'"
-                );
-
-                let always_inline = llvm::AttributeKind::AlwaysInline.create_attr(cx.llcx);
-                attributes::apply_to_llfn(function, Function, &[always_inline]);
-            }
-        }
-
         let opt_stage = llvm::OptStage::FatLTO;
         let stage = write::AutodiffStage::PostAD;
         if !config.autodiff.contains(&config::AutoDiff::NoPostopt) {
             unsafe {
-                write::llvm_optimize(cgcx, dcx, module, None, config, opt_level, opt_stage, stage)?;
+                write::llvm_optimize(cgcx, dcx, module, None, config, opt_level, opt_stage, stage);
             }
         }
 
@@ -634,7 +607,6 @@ pub(crate) fn run_pass_manager(
     }
 
     debug!("lto done");
-    Ok(())
 }
 
 pub struct ModuleBuffer(&'static mut llvm::ModuleBuffer);
@@ -727,7 +699,7 @@ impl Drop for ThinBuffer {
 pub(crate) fn optimize_thin_module(
     thin_module: ThinModule<LlvmCodegenBackend>,
     cgcx: &CodegenContext<LlvmCodegenBackend>,
-) -> Result<ModuleCodegen<ModuleLlvm>, FatalError> {
+) -> ModuleCodegen<ModuleLlvm> {
     let dcx = cgcx.create_dcx();
     let dcx = dcx.handle();
 
@@ -738,7 +710,7 @@ pub(crate) fn optimize_thin_module(
     // into that context. One day, however, we may do this for upstream
     // crates but for locally codegened modules we may be able to reuse
     // that LLVM Context and Module.
-    let module_llvm = ModuleLlvm::parse(cgcx, module_name, thin_module.data(), dcx)?;
+    let module_llvm = ModuleLlvm::parse(cgcx, module_name, thin_module.data(), dcx);
     let mut module = ModuleCodegen::new_regular(thin_module.name(), module_llvm);
     // Given that the newly created module lacks a thinlto buffer for embedding, we need to re-add it here.
     if cgcx.config(ModuleKind::Regular).embed_bitcode() {
@@ -772,7 +744,7 @@ pub(crate) fn optimize_thin_module(
                 .generic_activity_with_arg("LLVM_thin_lto_resolve_weak", thin_module.name());
             if unsafe { !llvm::LLVMRustPrepareThinLTOResolveWeak(thin_module.shared.data.0, llmod) }
             {
-                return Err(write::llvm_err(dcx, LlvmError::PrepareThinLtoModule));
+                write::llvm_err(dcx, LlvmError::PrepareThinLtoModule);
             }
             save_temp_bitcode(cgcx, &module, "thin-lto-after-resolve");
         }
@@ -783,7 +755,7 @@ pub(crate) fn optimize_thin_module(
                 .generic_activity_with_arg("LLVM_thin_lto_internalize", thin_module.name());
             if unsafe { !llvm::LLVMRustPrepareThinLTOInternalize(thin_module.shared.data.0, llmod) }
             {
-                return Err(write::llvm_err(dcx, LlvmError::PrepareThinLtoModule));
+                write::llvm_err(dcx, LlvmError::PrepareThinLtoModule);
             }
             save_temp_bitcode(cgcx, &module, "thin-lto-after-internalize");
         }
@@ -794,7 +766,7 @@ pub(crate) fn optimize_thin_module(
             if unsafe {
                 !llvm::LLVMRustPrepareThinLTOImport(thin_module.shared.data.0, llmod, target.raw())
             } {
-                return Err(write::llvm_err(dcx, LlvmError::PrepareThinLtoModule));
+                write::llvm_err(dcx, LlvmError::PrepareThinLtoModule);
             }
             save_temp_bitcode(cgcx, &module, "thin-lto-after-import");
         }
@@ -806,11 +778,11 @@ pub(crate) fn optimize_thin_module(
         // little differently.
         {
             info!("running thin lto passes over {}", module.name);
-            run_pass_manager(cgcx, dcx, &mut module, true)?;
+            run_pass_manager(cgcx, dcx, &mut module, true);
             save_temp_bitcode(cgcx, &module, "thin-lto-after-pm");
         }
     }
-    Ok(module)
+    module
 }
 
 /// Maps LLVM module identifiers to their corresponding LLVM LTO cache keys
@@ -876,9 +848,9 @@ pub(crate) fn parse_module<'a>(
     name: &CStr,
     data: &[u8],
     dcx: DiagCtxtHandle<'_>,
-) -> Result<&'a llvm::Module, FatalError> {
+) -> &'a llvm::Module {
     unsafe {
         llvm::LLVMRustParseBitcodeForLTO(cx, data.as_ptr(), data.len(), name.as_ptr())
-            .ok_or_else(|| write::llvm_err(dcx, LlvmError::ParseBitcode))
+            .unwrap_or_else(|| write::llvm_err(dcx, LlvmError::ParseBitcode))
     }
 }
diff --git a/compiler/rustc_codegen_llvm/src/back/mod.rs b/compiler/rustc_codegen_llvm/src/back/mod.rs
new file mode 100644
index 00000000000..6cb89f80ab8
--- /dev/null
+++ b/compiler/rustc_codegen_llvm/src/back/mod.rs
@@ -0,0 +1,5 @@
+pub(crate) mod archive;
+pub(crate) mod lto;
+pub(crate) mod owned_target_machine;
+mod profiling;
+pub(crate) mod write;
diff --git a/compiler/rustc_codegen_llvm/src/back/owned_target_machine.rs b/compiler/rustc_codegen_llvm/src/back/owned_target_machine.rs
index 8e82013e94a..6d8178320fe 100644
--- a/compiler/rustc_codegen_llvm/src/back/owned_target_machine.rs
+++ b/compiler/rustc_codegen_llvm/src/back/owned_target_machine.rs
@@ -1,4 +1,5 @@
-use std::ffi::{CStr, c_char};
+use std::assert_matches::assert_matches;
+use std::ffi::CStr;
 use std::marker::PhantomData;
 use std::ptr::NonNull;
 
@@ -41,11 +42,9 @@ impl OwnedTargetMachine {
         args_cstr_buff: &[u8],
         use_wasm_eh: bool,
     ) -> Result<Self, LlvmError<'static>> {
-        assert!(args_cstr_buff.len() > 0);
-        assert!(
-            *args_cstr_buff.last().unwrap() == 0,
-            "The last character must be a null terminator."
-        );
+        // The argument list is passed as the concatenation of one or more C strings.
+        // This implies that there must be a last byte, and it must be 0.
+        assert_matches!(args_cstr_buff, [.., b'\0'], "the last byte must be a NUL terminator");
 
         // SAFETY: llvm::LLVMRustCreateTargetMachine copies pointed to data
         let tm_ptr = unsafe {
@@ -71,7 +70,7 @@ impl OwnedTargetMachine {
                 output_obj_file.as_ptr(),
                 debug_info_compression.as_ptr(),
                 use_emulated_tls,
-                args_cstr_buff.as_ptr() as *const c_char,
+                args_cstr_buff.as_ptr(),
                 args_cstr_buff.len(),
                 use_wasm_eh,
             )
@@ -99,7 +98,7 @@ impl Drop for OwnedTargetMachine {
         // llvm::LLVMRustCreateTargetMachine OwnedTargetMachine is not copyable so there is no
         // double free or use after free.
         unsafe {
-            llvm::LLVMRustDisposeTargetMachine(self.tm_unique.as_mut());
+            llvm::LLVMRustDisposeTargetMachine(self.tm_unique.as_ptr());
         }
     }
 }
diff --git a/compiler/rustc_codegen_llvm/src/back/write.rs b/compiler/rustc_codegen_llvm/src/back/write.rs
index 85a06f457eb..7ea2ae6673b 100644
--- a/compiler/rustc_codegen_llvm/src/back/write.rs
+++ b/compiler/rustc_codegen_llvm/src/back/write.rs
@@ -20,7 +20,7 @@ use rustc_codegen_ssa::traits::*;
 use rustc_codegen_ssa::{CompiledModule, ModuleCodegen, ModuleKind};
 use rustc_data_structures::profiling::SelfProfilerRef;
 use rustc_data_structures::small_c_str::SmallCStr;
-use rustc_errors::{DiagCtxtHandle, FatalError, Level};
+use rustc_errors::{DiagCtxtHandle, Level};
 use rustc_fs_util::{link_or_copy, path_to_c_string};
 use rustc_middle::ty::TyCtxt;
 use rustc_session::Session;
@@ -46,10 +46,10 @@ use crate::llvm::{self, DiagnosticInfo};
 use crate::type_::Type;
 use crate::{LlvmCodegenBackend, ModuleLlvm, base, common, llvm_util};
 
-pub(crate) fn llvm_err<'a>(dcx: DiagCtxtHandle<'_>, err: LlvmError<'a>) -> FatalError {
+pub(crate) fn llvm_err<'a>(dcx: DiagCtxtHandle<'_>, err: LlvmError<'a>) -> ! {
     match llvm::last_error() {
-        Some(llvm_err) => dcx.emit_almost_fatal(WithLlvmError(err, llvm_err)),
-        None => dcx.emit_almost_fatal(err),
+        Some(llvm_err) => dcx.emit_fatal(WithLlvmError(err, llvm_err)),
+        None => dcx.emit_fatal(err),
     }
 }
 
@@ -63,7 +63,7 @@ fn write_output_file<'ll>(
     file_type: llvm::FileType,
     self_profiler_ref: &SelfProfilerRef,
     verify_llvm_ir: bool,
-) -> Result<(), FatalError> {
+) {
     debug!("write_output_file output={:?} dwo_output={:?}", output, dwo_output);
     let output_c = path_to_c_string(output);
     let dwo_output_c;
@@ -100,7 +100,7 @@ fn write_output_file<'ll>(
         }
     }
 
-    result.into_result().map_err(|()| llvm_err(dcx, LlvmError::WriteOutput { path: output }))
+    result.into_result().unwrap_or_else(|()| llvm_err(dcx, LlvmError::WriteOutput { path: output }))
 }
 
 pub(crate) fn create_informational_target_machine(
@@ -112,7 +112,7 @@ pub(crate) fn create_informational_target_machine(
     // system/tcx is set up.
     let features = llvm_util::global_llvm_features(sess, false, only_base_features);
     target_machine_factory(sess, config::OptLevel::No, &features)(config)
-        .unwrap_or_else(|err| llvm_err(sess.dcx(), err).raise())
+        .unwrap_or_else(|err| llvm_err(sess.dcx(), err))
 }
 
 pub(crate) fn create_target_machine(tcx: TyCtxt<'_>, mod_name: &str) -> OwnedTargetMachine {
@@ -139,7 +139,7 @@ pub(crate) fn create_target_machine(tcx: TyCtxt<'_>, mod_name: &str) -> OwnedTar
         tcx.backend_optimization_level(()),
         tcx.global_backend_features(()),
     )(config)
-    .unwrap_or_else(|err| llvm_err(tcx.dcx(), err).raise())
+    .unwrap_or_else(|err| llvm_err(tcx.dcx(), err))
 }
 
 fn to_llvm_opt_settings(cfg: config::OptLevel) -> (llvm::CodeGenOptLevel, llvm::CodeGenOptSize) {
@@ -565,7 +565,7 @@ pub(crate) unsafe fn llvm_optimize(
     opt_level: config::OptLevel,
     opt_stage: llvm::OptStage,
     autodiff_stage: AutodiffStage,
-) -> Result<(), FatalError> {
+) {
     // Enzyme:
     // The whole point of compiler based AD is to differentiate optimized IR instead of unoptimized
     // source code. However, benchmarks show that optimizations increasing the code size
@@ -704,7 +704,7 @@ pub(crate) unsafe fn llvm_optimize(
             llvm_plugins.len(),
         )
     };
-    result.into_result().map_err(|()| llvm_err(dcx, LlvmError::RunLlvmPasses))
+    result.into_result().unwrap_or_else(|()| llvm_err(dcx, LlvmError::RunLlvmPasses))
 }
 
 // Unsafe due to LLVM calls.
@@ -713,7 +713,7 @@ pub(crate) fn optimize(
     dcx: DiagCtxtHandle<'_>,
     module: &mut ModuleCodegen<ModuleLlvm>,
     config: &ModuleConfig,
-) -> Result<(), FatalError> {
+) {
     let _timer = cgcx.prof.generic_activity_with_arg("LLVM_module_optimize", &*module.name);
 
     let llcx = &*module.module_llvm.llcx;
@@ -765,7 +765,7 @@ pub(crate) fn optimize(
                 opt_stage,
                 autodiff_stage,
             )
-        }?;
+        };
         if let Some(thin_lto_buffer) = thin_lto_buffer {
             let thin_lto_buffer = unsafe { ThinBuffer::from_raw_ptr(thin_lto_buffer) };
             module.thin_lto_buffer = Some(thin_lto_buffer.data().to_vec());
@@ -793,14 +793,13 @@ pub(crate) fn optimize(
             }
         }
     }
-    Ok(())
 }
 
 pub(crate) fn codegen(
     cgcx: &CodegenContext<LlvmCodegenBackend>,
     module: ModuleCodegen<ModuleLlvm>,
     config: &ModuleConfig,
-) -> Result<CompiledModule, FatalError> {
+) -> CompiledModule {
     let dcx = cgcx.create_dcx();
     let dcx = dcx.handle();
 
@@ -862,7 +861,7 @@ pub(crate) fn codegen(
                     .generic_activity_with_arg("LLVM_module_codegen_embed_bitcode", &*module.name);
                 let thin_bc =
                     module.thin_lto_buffer.as_deref().expect("cannot find embedded bitcode");
-                embed_bitcode(cgcx, llcx, llmod, &config.bc_cmdline, &thin_bc);
+                embed_bitcode(cgcx, llcx, llmod, &thin_bc);
             }
         }
 
@@ -909,7 +908,9 @@ pub(crate) fn codegen(
                 record_artifact_size(&cgcx.prof, "llvm_ir", &out);
             }
 
-            result.into_result().map_err(|()| llvm_err(dcx, LlvmError::WriteIr { path: &out }))?;
+            result
+                .into_result()
+                .unwrap_or_else(|()| llvm_err(dcx, LlvmError::WriteIr { path: &out }));
         }
 
         if config.emit_asm {
@@ -940,7 +941,7 @@ pub(crate) fn codegen(
                 llvm::FileType::AssemblyFile,
                 &cgcx.prof,
                 config.verify_llvm_ir,
-            )?;
+            );
         }
 
         match config.emit_obj {
@@ -976,7 +977,7 @@ pub(crate) fn codegen(
                     llvm::FileType::ObjectFile,
                     &cgcx.prof,
                     config.verify_llvm_ir,
-                )?;
+                );
             }
 
             EmitObj::Bitcode => {
@@ -1009,7 +1010,7 @@ pub(crate) fn codegen(
         && cgcx.target_can_use_split_dwarf
         && cgcx.split_debuginfo != SplitDebuginfo::Off
         && cgcx.split_dwarf_kind == SplitDwarfKind::Split;
-    Ok(module.into_compiled_module(
+    module.into_compiled_module(
         config.emit_obj != EmitObj::None,
         dwarf_object_emitted,
         config.emit_bc,
@@ -1017,7 +1018,7 @@ pub(crate) fn codegen(
         config.emit_ir,
         &cgcx.output_filenames,
         cgcx.invocation_temp.as_deref(),
-    ))
+    )
 }
 
 fn create_section_with_flags_asm(section_name: &str, section_flags: &str, data: &[u8]) -> Vec<u8> {
@@ -1058,7 +1059,6 @@ fn embed_bitcode(
     cgcx: &CodegenContext<LlvmCodegenBackend>,
     llcx: &llvm::Context,
     llmod: &llvm::Module,
-    cmdline: &str,
     bitcode: &[u8],
 ) {
     // We're adding custom sections to the output object file, but we definitely
@@ -1074,7 +1074,9 @@ fn embed_bitcode(
     // * Mach-O - this is for macOS. Inspecting the source code for the native
     //   linker here shows that the `.llvmbc` and `.llvmcmd` sections are
     //   automatically skipped by the linker. In that case there's nothing extra
-    //   that we need to do here.
+    //   that we need to do here. We do need to make sure that the
+    //   `__LLVM,__cmdline` section exists even though it is empty as otherwise
+    //   ld64 rejects the object file.
     //
     // * Wasm - the native LLD linker is hard-coded to skip `.llvmbc` and
     //   `.llvmcmd` sections, so there's nothing extra we need to do.
@@ -1109,9 +1111,9 @@ fn embed_bitcode(
 
         llvm::set_section(llglobal, bitcode_section_name(cgcx));
         llvm::set_linkage(llglobal, llvm::Linkage::PrivateLinkage);
-        llvm::LLVMSetGlobalConstant(llglobal, llvm::True);
+        llvm::LLVMSetGlobalConstant(llglobal, llvm::TRUE);
 
-        let llconst = common::bytes_in_context(llcx, cmdline.as_bytes());
+        let llconst = common::bytes_in_context(llcx, &[]);
         let llglobal = llvm::add_global(llmod, common::val_ty(llconst), c"rustc.embedded.cmdline");
         llvm::set_initializer(llglobal, llconst);
         let section = if cgcx.target_is_like_darwin {
@@ -1128,7 +1130,7 @@ fn embed_bitcode(
         let section_flags = if cgcx.is_pe_coff { "n" } else { "e" };
         let asm = create_section_with_flags_asm(".llvmbc", section_flags, bitcode);
         llvm::append_module_inline_asm(llmod, &asm);
-        let asm = create_section_with_flags_asm(".llvmcmd", section_flags, cmdline.as_bytes());
+        let asm = create_section_with_flags_asm(".llvmcmd", section_flags, &[]);
         llvm::append_module_inline_asm(llmod, &asm);
     }
 }
diff --git a/compiler/rustc_codegen_llvm/src/base.rs b/compiler/rustc_codegen_llvm/src/base.rs
index 5dda836988c..9cc5d8dbc21 100644
--- a/compiler/rustc_codegen_llvm/src/base.rs
+++ b/compiler/rustc_codegen_llvm/src/base.rs
@@ -18,9 +18,10 @@ use rustc_codegen_ssa::base::maybe_create_entry_wrapper;
 use rustc_codegen_ssa::mono_item::MonoItemExt;
 use rustc_codegen_ssa::traits::*;
 use rustc_data_structures::small_c_str::SmallCStr;
+use rustc_hir::attrs::Linkage;
 use rustc_middle::dep_graph;
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
-use rustc_middle::mir::mono::{Linkage, Visibility};
+use rustc_middle::mir::mono::Visibility;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::config::DebugInfo;
 use rustc_span::Symbol;
diff --git a/compiler/rustc_codegen_llvm/src/builder.rs b/compiler/rustc_codegen_llvm/src/builder.rs
index 917d07e3c61..37379586d58 100644
--- a/compiler/rustc_codegen_llvm/src/builder.rs
+++ b/compiler/rustc_codegen_llvm/src/builder.rs
@@ -35,7 +35,7 @@ use crate::attributes;
 use crate::common::Funclet;
 use crate::context::{CodegenCx, FullCx, GenericCx, SCx};
 use crate::llvm::{
-    self, AtomicOrdering, AtomicRmwBinOp, BasicBlock, False, GEPNoWrapFlags, Metadata, True,
+    self, AtomicOrdering, AtomicRmwBinOp, BasicBlock, GEPNoWrapFlags, Metadata, TRUE, ToLlvmBool,
 };
 use crate::type_::Type;
 use crate::type_of::LayoutLlvmExt;
@@ -493,8 +493,8 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         unsafe {
             let add = llvm::LLVMBuildAdd(self.llbuilder, a, b, UNNAMED);
             if llvm::LLVMIsAInstruction(add).is_some() {
-                llvm::LLVMSetNUW(add, True);
-                llvm::LLVMSetNSW(add, True);
+                llvm::LLVMSetNUW(add, TRUE);
+                llvm::LLVMSetNSW(add, TRUE);
             }
             add
         }
@@ -503,8 +503,8 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         unsafe {
             let sub = llvm::LLVMBuildSub(self.llbuilder, a, b, UNNAMED);
             if llvm::LLVMIsAInstruction(sub).is_some() {
-                llvm::LLVMSetNUW(sub, True);
-                llvm::LLVMSetNSW(sub, True);
+                llvm::LLVMSetNUW(sub, TRUE);
+                llvm::LLVMSetNSW(sub, TRUE);
             }
             sub
         }
@@ -513,8 +513,8 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         unsafe {
             let mul = llvm::LLVMBuildMul(self.llbuilder, a, b, UNNAMED);
             if llvm::LLVMIsAInstruction(mul).is_some() {
-                llvm::LLVMSetNUW(mul, True);
-                llvm::LLVMSetNSW(mul, True);
+                llvm::LLVMSetNUW(mul, TRUE);
+                llvm::LLVMSetNSW(mul, TRUE);
             }
             mul
         }
@@ -528,7 +528,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
             // an instruction, so we need to check before setting the flag.
             // (See also `LLVMBuildNUWNeg` which also needs a check.)
             if llvm::LLVMIsAInstruction(or).is_some() {
-                llvm::LLVMSetIsDisjoint(or, True);
+                llvm::LLVMSetIsDisjoint(or, TRUE);
             }
             or
         }
@@ -629,7 +629,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
     fn volatile_load(&mut self, ty: &'ll Type, ptr: &'ll Value) -> &'ll Value {
         unsafe {
             let load = llvm::LLVMBuildLoad2(self.llbuilder, ty, ptr, UNNAMED);
-            llvm::LLVMSetVolatile(load, llvm::True);
+            llvm::LLVMSetVolatile(load, llvm::TRUE);
             load
         }
     }
@@ -717,7 +717,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
             let mut const_llval = None;
             let llty = place.layout.llvm_type(self);
             if let Some(global) = llvm::LLVMIsAGlobalVariable(place.val.llval) {
-                if llvm::LLVMIsGlobalConstant(global) == llvm::True {
+                if llvm::LLVMIsGlobalConstant(global).is_true() {
                     if let Some(init) = llvm::LLVMGetInitializer(global) {
                         if self.val_ty(init) == llty {
                             const_llval = Some(init);
@@ -838,7 +838,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
                 if flags.contains(MemFlags::UNALIGNED) { 1 } else { align.bytes() as c_uint };
             llvm::LLVMSetAlignment(store, align);
             if flags.contains(MemFlags::VOLATILE) {
-                llvm::LLVMSetVolatile(store, llvm::True);
+                llvm::LLVMSetVolatile(store, llvm::TRUE);
             }
             if flags.contains(MemFlags::NONTEMPORAL) {
                 // Make sure that the current target architectures supports "sane" non-temporal
@@ -956,7 +956,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         let trunc = self.trunc(val, dest_ty);
         unsafe {
             if llvm::LLVMIsAInstruction(trunc).is_some() {
-                llvm::LLVMSetNUW(trunc, True);
+                llvm::LLVMSetNUW(trunc, TRUE);
             }
         }
         trunc
@@ -968,7 +968,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         let trunc = self.trunc(val, dest_ty);
         unsafe {
             if llvm::LLVMIsAInstruction(trunc).is_some() {
-                llvm::LLVMSetNSW(trunc, True);
+                llvm::LLVMSetNSW(trunc, TRUE);
             }
         }
         trunc
@@ -1067,13 +1067,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
 
     fn intcast(&mut self, val: &'ll Value, dest_ty: &'ll Type, is_signed: bool) -> &'ll Value {
         unsafe {
-            llvm::LLVMBuildIntCast2(
-                self.llbuilder,
-                val,
-                dest_ty,
-                if is_signed { True } else { False },
-                UNNAMED,
-            )
+            llvm::LLVMBuildIntCast2(self.llbuilder, val, dest_ty, is_signed.to_llvm_bool(), UNNAMED)
         }
     }
 
@@ -1229,7 +1223,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         let ty = self.type_struct(&[self.type_ptr(), self.type_i32()], false);
         let landing_pad = self.landing_pad(ty, pers_fn, 0);
         unsafe {
-            llvm::LLVMSetCleanup(landing_pad, llvm::True);
+            llvm::LLVMSetCleanup(landing_pad, llvm::TRUE);
         }
         (self.extract_value(landing_pad, 0), self.extract_value(landing_pad, 1))
     }
@@ -1317,7 +1311,6 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         failure_order: rustc_middle::ty::AtomicOrdering,
         weak: bool,
     ) -> (&'ll Value, &'ll Value) {
-        let weak = if weak { llvm::True } else { llvm::False };
         unsafe {
             let value = llvm::LLVMBuildAtomicCmpXchg(
                 self.llbuilder,
@@ -1326,9 +1319,9 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
                 src,
                 AtomicOrdering::from_generic(order),
                 AtomicOrdering::from_generic(failure_order),
-                llvm::False, // SingleThreaded
+                llvm::FALSE, // SingleThreaded
             );
-            llvm::LLVMSetWeak(value, weak);
+            llvm::LLVMSetWeak(value, weak.to_llvm_bool());
             let val = self.extract_value(value, 0);
             let success = self.extract_value(value, 1);
             (val, success)
@@ -1353,7 +1346,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
                 dst,
                 src,
                 AtomicOrdering::from_generic(order),
-                llvm::False, // SingleThreaded
+                llvm::FALSE, // SingleThreaded
             )
         };
         if ret_ptr && self.val_ty(res) != self.type_ptr() {
@@ -1368,14 +1361,14 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         scope: SynchronizationScope,
     ) {
         let single_threaded = match scope {
-            SynchronizationScope::SingleThread => llvm::True,
-            SynchronizationScope::CrossThread => llvm::False,
+            SynchronizationScope::SingleThread => true,
+            SynchronizationScope::CrossThread => false,
         };
         unsafe {
             llvm::LLVMBuildFence(
                 self.llbuilder,
                 AtomicOrdering::from_generic(order),
-                single_threaded,
+                single_threaded.to_llvm_bool(),
                 UNNAMED,
             );
         }
@@ -1453,7 +1446,7 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         instance: Option<Instance<'tcx>>,
     ) {
         let call = self.call(llty, fn_attrs, Some(fn_abi), llfn, args, funclet, instance);
-        llvm::LLVMRustSetTailCallKind(call, llvm::TailCallKind::MustTail);
+        llvm::LLVMSetTailCallKind(call, llvm::TailCallKind::MustTail);
 
         match &fn_abi.ret.mode {
             PassMode::Ignore | PassMode::Indirect { .. } => self.ret_void(),
@@ -1696,7 +1689,11 @@ impl<'a, 'll, 'tcx> Builder<'a, 'll, 'tcx> {
             return;
         }
 
-        self.call_intrinsic(intrinsic, &[self.val_ty(ptr)], &[self.cx.const_u64(size), ptr]);
+        if crate::llvm_util::get_version() >= (22, 0, 0) {
+            self.call_intrinsic(intrinsic, &[self.val_ty(ptr)], &[ptr]);
+        } else {
+            self.call_intrinsic(intrinsic, &[self.val_ty(ptr)], &[self.cx.const_u64(size), ptr]);
+        }
     }
 }
 impl<'a, 'll, CX: Borrow<SCx<'ll>>> GenericBuilder<'a, 'll, CX> {
diff --git a/compiler/rustc_codegen_llvm/src/builder/autodiff.rs b/compiler/rustc_codegen_llvm/src/builder/autodiff.rs
index 829b3c513c2..6ddf53cdc87 100644
--- a/compiler/rustc_codegen_llvm/src/builder/autodiff.rs
+++ b/compiler/rustc_codegen_llvm/src/builder/autodiff.rs
@@ -1,40 +1,92 @@
 use std::ptr;
 
-use rustc_ast::expand::autodiff_attrs::{AutoDiffAttrs, AutoDiffItem, DiffActivity, DiffMode};
-use rustc_codegen_ssa::ModuleCodegen;
+use rustc_ast::expand::autodiff_attrs::{AutoDiffAttrs, DiffActivity, DiffMode};
 use rustc_codegen_ssa::common::TypeKind;
-use rustc_codegen_ssa::traits::BaseTypeCodegenMethods;
-use rustc_errors::FatalError;
-use rustc_middle::bug;
-use tracing::{debug, trace};
+use rustc_codegen_ssa::traits::{BaseTypeCodegenMethods, BuilderMethods};
+use rustc_middle::ty::{PseudoCanonicalInput, Ty, TyCtxt, TypingEnv};
+use rustc_middle::{bug, ty};
+use tracing::debug;
 
-use crate::back::write::llvm_err;
-use crate::builder::{SBuilder, UNNAMED};
+use crate::builder::{Builder, PlaceRef, UNNAMED};
 use crate::context::SimpleCx;
 use crate::declare::declare_simple_fn;
-use crate::errors::{AutoDiffWithoutEnable, LlvmError};
-use crate::llvm::AttributePlace::Function;
-use crate::llvm::{Metadata, True};
+use crate::llvm;
+use crate::llvm::{Metadata, TRUE, Type};
 use crate::value::Value;
-use crate::{CodegenContext, LlvmCodegenBackend, ModuleLlvm, attributes, llvm};
 
-fn get_params(fnc: &Value) -> Vec<&Value> {
-    let param_num = llvm::LLVMCountParams(fnc) as usize;
-    let mut fnc_args: Vec<&Value> = vec![];
-    fnc_args.reserve(param_num);
-    unsafe {
-        llvm::LLVMGetParams(fnc, fnc_args.as_mut_ptr());
-        fnc_args.set_len(param_num);
+pub(crate) fn adjust_activity_to_abi<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    fn_ty: Ty<'tcx>,
+    da: &mut Vec<DiffActivity>,
+) {
+    if !matches!(fn_ty.kind(), ty::FnDef(..)) {
+        bug!("expected fn def for autodiff, got {:?}", fn_ty);
     }
-    fnc_args
-}
 
-fn has_sret(fnc: &Value) -> bool {
-    let num_args = llvm::LLVMCountParams(fnc) as usize;
-    if num_args == 0 {
-        false
-    } else {
-        unsafe { llvm::LLVMRustHasAttributeAtIndex(fnc, 0, llvm::AttributeKind::StructRet) }
+    // We don't actually pass the types back into the type system.
+    // All we do is decide how to handle the arguments.
+    let sig = fn_ty.fn_sig(tcx).skip_binder();
+
+    let mut new_activities = vec![];
+    let mut new_positions = vec![];
+    for (i, ty) in sig.inputs().iter().enumerate() {
+        if let Some(inner_ty) = ty.builtin_deref(true) {
+            if inner_ty.is_slice() {
+                // Now we need to figure out the size of each slice element in memory to allow
+                // safety checks and usability improvements in the backend.
+                let sty = match inner_ty.builtin_index() {
+                    Some(sty) => sty,
+                    None => {
+                        panic!("slice element type unknown");
+                    }
+                };
+                let pci = PseudoCanonicalInput {
+                    typing_env: TypingEnv::fully_monomorphized(),
+                    value: sty,
+                };
+
+                let layout = tcx.layout_of(pci);
+                let elem_size = match layout {
+                    Ok(layout) => layout.size,
+                    Err(_) => {
+                        bug!("autodiff failed to compute slice element size");
+                    }
+                };
+                let elem_size: u32 = elem_size.bytes() as u32;
+
+                // We know that the length will be passed as extra arg.
+                if !da.is_empty() {
+                    // We are looking at a slice. The length of that slice will become an
+                    // extra integer on llvm level. Integers are always const.
+                    // However, if the slice get's duplicated, we want to know to later check the
+                    // size. So we mark the new size argument as FakeActivitySize.
+                    // There is one FakeActivitySize per slice, so for convenience we store the
+                    // slice element size in bytes in it. We will use the size in the backend.
+                    let activity = match da[i] {
+                        DiffActivity::DualOnly
+                        | DiffActivity::Dual
+                        | DiffActivity::Dualv
+                        | DiffActivity::DuplicatedOnly
+                        | DiffActivity::Duplicated => {
+                            DiffActivity::FakeActivitySize(Some(elem_size))
+                        }
+                        DiffActivity::Const => DiffActivity::Const,
+                        _ => bug!("unexpected activity for ptr/ref"),
+                    };
+                    new_activities.push(activity);
+                    new_positions.push(i + 1);
+                }
+
+                continue;
+            }
+        }
+    }
+    // now add the extra activities coming from slices
+    // Reverse order to not invalidate the indices
+    for _ in 0..new_activities.len() {
+        let pos = new_positions.pop().unwrap();
+        let activity = new_activities.pop().unwrap();
+        da.insert(pos, activity);
     }
 }
 
@@ -48,14 +100,13 @@ fn has_sret(fnc: &Value) -> bool {
 // need to match those.
 // FIXME(ZuseZ4): This logic is a bit more complicated than it should be, can we simplify it
 // using iterators and peek()?
-fn match_args_from_caller_to_enzyme<'ll>(
+fn match_args_from_caller_to_enzyme<'ll, 'tcx>(
     cx: &SimpleCx<'ll>,
-    builder: &SBuilder<'ll, 'll>,
+    builder: &mut Builder<'_, 'll, 'tcx>,
     width: u32,
     args: &mut Vec<&'ll llvm::Value>,
     inputs: &[DiffActivity],
     outer_args: &[&'ll llvm::Value],
-    has_sret: bool,
 ) {
     debug!("matching autodiff arguments");
     // We now handle the issue that Rust level arguments not always match the llvm-ir level
@@ -67,14 +118,6 @@ fn match_args_from_caller_to_enzyme<'ll>(
     let mut outer_pos: usize = 0;
     let mut activity_pos = 0;
 
-    if has_sret {
-        // Then the first outer arg is the sret pointer. Enzyme doesn't know about sret, so the
-        // inner function will still return something. We increase our outer_pos by one,
-        // and once we're done with all other args we will take the return of the inner call and
-        // update the sret pointer with it
-        outer_pos = 1;
-    }
-
     let enzyme_const = cx.create_metadata(b"enzyme_const");
     let enzyme_out = cx.create_metadata(b"enzyme_out");
     let enzyme_dup = cx.create_metadata(b"enzyme_dup");
@@ -193,92 +236,6 @@ fn match_args_from_caller_to_enzyme<'ll>(
     }
 }
 
-// On LLVM-IR, we can luckily declare __enzyme_ functions without specifying the input
-// arguments. We do however need to declare them with their correct return type.
-// We already figured the correct return type out in our frontend, when generating the outer_fn,
-// so we can now just go ahead and use that. This is not always trivial, e.g. because sret.
-// Beyond sret, this article describes our challenges nicely:
-// <https://yorickpeterse.com/articles/the-mess-that-is-handling-structure-arguments-and-returns-in-llvm/>
-// I.e. (i32, f32) will get merged into i64, but we don't handle that yet.
-fn compute_enzyme_fn_ty<'ll>(
-    cx: &SimpleCx<'ll>,
-    attrs: &AutoDiffAttrs,
-    fn_to_diff: &'ll Value,
-    outer_fn: &'ll Value,
-) -> &'ll llvm::Type {
-    let fn_ty = cx.get_type_of_global(outer_fn);
-    let mut ret_ty = cx.get_return_type(fn_ty);
-
-    let has_sret = has_sret(outer_fn);
-
-    if has_sret {
-        // Now we don't just forward the return type, so we have to figure it out based on the
-        // primal return type, in combination with the autodiff settings.
-        let fn_ty = cx.get_type_of_global(fn_to_diff);
-        let inner_ret_ty = cx.get_return_type(fn_ty);
-
-        let void_ty = unsafe { llvm::LLVMVoidTypeInContext(cx.llcx) };
-        if inner_ret_ty == void_ty {
-            // This indicates that even the inner function has an sret.
-            // Right now I only look for an sret in the outer function.
-            // This *probably* needs some extra handling, but I never ran
-            // into such a case. So I'll wait for user reports to have a test case.
-            bug!("sret in inner function");
-        }
-
-        if attrs.width == 1 {
-            // Enzyme returns a struct of style:
-            // `{ original_ret(if requested), float, float, ... }`
-            let mut struct_elements = vec![];
-            if attrs.has_primal_ret() {
-                struct_elements.push(inner_ret_ty);
-            }
-            // Next, we push the list of active floats, since they will be lowered to `enzyme_out`,
-            // and therefore part of the return struct.
-            let param_tys = cx.func_params_types(fn_ty);
-            for (act, param_ty) in attrs.input_activity.iter().zip(param_tys) {
-                if matches!(act, DiffActivity::Active) {
-                    // Now find the float type at position i based on the fn_ty,
-                    // to know what (f16/f32/f64/...) to add to the struct.
-                    struct_elements.push(param_ty);
-                }
-            }
-            ret_ty = cx.type_struct(&struct_elements, false);
-        } else {
-            // First we check if we also have to deal with the primal return.
-            match attrs.mode {
-                DiffMode::Forward => match attrs.ret_activity {
-                    DiffActivity::Dual => {
-                        let arr_ty =
-                            unsafe { llvm::LLVMArrayType2(inner_ret_ty, attrs.width as u64 + 1) };
-                        ret_ty = arr_ty;
-                    }
-                    DiffActivity::DualOnly => {
-                        let arr_ty =
-                            unsafe { llvm::LLVMArrayType2(inner_ret_ty, attrs.width as u64) };
-                        ret_ty = arr_ty;
-                    }
-                    DiffActivity::Const => {
-                        todo!("Not sure, do we need to do something here?");
-                    }
-                    _ => {
-                        bug!("unreachable");
-                    }
-                },
-                DiffMode::Reverse => {
-                    todo!("Handle sret for reverse mode");
-                }
-                _ => {
-                    bug!("unreachable");
-                }
-            }
-        }
-    }
-
-    // LLVM can figure out the input types on it's own, so we take a shortcut here.
-    unsafe { llvm::LLVMFunctionType(ret_ty, ptr::null(), 0, True) }
-}
-
 /// When differentiating `fn_to_diff`, take a `outer_fn` and generate another
 /// function with expected naming and calling conventions[^1] which will be
 /// discovered by the enzyme LLVM pass and its body populated with the differentiated
@@ -288,11 +245,15 @@ fn compute_enzyme_fn_ty<'ll>(
 /// [^1]: <https://enzyme.mit.edu/getting_started/CallingConvention/>
 // FIXME(ZuseZ4): `outer_fn` should include upstream safety checks to
 // cover some assumptions of enzyme/autodiff, which could lead to UB otherwise.
-fn generate_enzyme_call<'ll>(
+pub(crate) fn generate_enzyme_call<'ll, 'tcx>(
+    builder: &mut Builder<'_, 'll, 'tcx>,
     cx: &SimpleCx<'ll>,
     fn_to_diff: &'ll Value,
-    outer_fn: &'ll Value,
+    outer_name: &str,
+    ret_ty: &'ll Type,
+    fn_args: &[&'ll Value],
     attrs: AutoDiffAttrs,
+    dest: PlaceRef<'tcx, &'ll Value>,
 ) {
     // We have to pick the name depending on whether we want forward or reverse mode autodiff.
     let mut ad_name: String = match attrs.mode {
@@ -302,11 +263,9 @@ fn generate_enzyme_call<'ll>(
     }
     .to_string();
 
-    // add outer_fn name to ad_name to make it unique, in case users apply autodiff to multiple
+    // add outer_name to ad_name to make it unique, in case users apply autodiff to multiple
     // functions. Unwrap will only panic, if LLVM gave us an invalid string.
-    let name = llvm::get_value_name(outer_fn);
-    let outer_fn_name = std::str::from_utf8(&name).unwrap();
-    ad_name.push_str(outer_fn_name);
+    ad_name.push_str(outer_name);
 
     // Let us assume the user wrote the following function square:
     //
@@ -316,14 +275,8 @@ fn generate_enzyme_call<'ll>(
     //  %0 = fmul double %x, %x
     //  ret double %0
     // }
-    // ```
-    //
-    // The user now applies autodiff to the function square, in which case fn_to_diff will be `square`.
-    // Our macro generates the following placeholder code (slightly simplified):
     //
-    // ```llvm
     // define double @dsquare(double %x) {
-    //  ; placeholder code
     //  return 0.0;
     // }
     // ```
@@ -340,175 +293,44 @@ fn generate_enzyme_call<'ll>(
     //   ret double %0
     // }
     // ```
-    unsafe {
-        let enzyme_ty = compute_enzyme_fn_ty(cx, &attrs, fn_to_diff, outer_fn);
-
-        // FIXME(ZuseZ4): the CC/Addr/Vis values are best effort guesses, we should look at tests and
-        // think a bit more about what should go here.
-        let cc = llvm::LLVMGetFunctionCallConv(outer_fn);
-        let ad_fn = declare_simple_fn(
-            cx,
-            &ad_name,
-            llvm::CallConv::try_from(cc).expect("invalid callconv"),
-            llvm::UnnamedAddr::No,
-            llvm::Visibility::Default,
-            enzyme_ty,
-        );
-
-        // Otherwise LLVM might inline our temporary code before the enzyme pass has a chance to
-        // do it's work.
-        let attr = llvm::AttributeKind::NoInline.create_attr(cx.llcx);
-        attributes::apply_to_llfn(ad_fn, Function, &[attr]);
-
-        // We add a made-up attribute just such that we can recognize it after AD to update
-        // (no)-inline attributes. We'll then also remove this attribute.
-        let enzyme_marker_attr = llvm::CreateAttrString(cx.llcx, "enzyme_marker");
-        attributes::apply_to_llfn(outer_fn, Function, &[enzyme_marker_attr]);
-
-        // first, remove all calls from fnc
-        let entry = llvm::LLVMGetFirstBasicBlock(outer_fn);
-        let br = llvm::LLVMRustGetTerminator(entry);
-        llvm::LLVMRustEraseInstFromParent(br);
-
-        let last_inst = llvm::LLVMRustGetLastInstruction(entry).unwrap();
-        let mut builder = SBuilder::build(cx, entry);
-
-        let num_args = llvm::LLVMCountParams(&fn_to_diff);
-        let mut args = Vec::with_capacity(num_args as usize + 1);
-        args.push(fn_to_diff);
-
-        let enzyme_primal_ret = cx.create_metadata(b"enzyme_primal_return");
-        if matches!(attrs.ret_activity, DiffActivity::Dual | DiffActivity::Active) {
-            args.push(cx.get_metadata_value(enzyme_primal_ret));
-        }
-        if attrs.width > 1 {
-            let enzyme_width = cx.create_metadata(b"enzyme_width");
-            args.push(cx.get_metadata_value(enzyme_width));
-            args.push(cx.get_const_int(cx.type_i64(), attrs.width as u64));
-        }
-
-        let has_sret = has_sret(outer_fn);
-        let outer_args: Vec<&llvm::Value> = get_params(outer_fn);
-        match_args_from_caller_to_enzyme(
-            &cx,
-            &builder,
-            attrs.width,
-            &mut args,
-            &attrs.input_activity,
-            &outer_args,
-            has_sret,
-        );
-
-        let call = builder.call(enzyme_ty, ad_fn, &args, None);
-
-        // This part is a bit iffy. LLVM requires that a call to an inlineable function has some
-        // metadata attached to it, but we just created this code oota. Given that the
-        // differentiated function already has partly confusing metadata, and given that this
-        // affects nothing but the auttodiff IR, we take a shortcut and just steal metadata from the
-        // dummy code which we inserted at a higher level.
-        // FIXME(ZuseZ4): Work with Enzyme core devs to clarify what debug metadata issues we have,
-        // and how to best improve it for enzyme core and rust-enzyme.
-        let md_ty = cx.get_md_kind_id("dbg");
-        if llvm::LLVMRustHasMetadata(last_inst, md_ty) {
-            let md = llvm::LLVMRustDIGetInstMetadata(last_inst)
-                .expect("failed to get instruction metadata");
-            let md_todiff = cx.get_metadata_value(md);
-            llvm::LLVMSetMetadata(call, md_ty, md_todiff);
-        } else {
-            // We don't panic, since depending on whether we are in debug or release mode, we might
-            // have no debug info to copy, which would then be ok.
-            trace!("no dbg info");
-        }
-
-        // Now that we copied the metadata, get rid of dummy code.
-        llvm::LLVMRustEraseInstUntilInclusive(entry, last_inst);
-
-        if cx.val_ty(call) == cx.type_void() || has_sret {
-            if has_sret {
-                // This is what we already have in our outer_fn (shortened):
-                // define void @_foo(ptr <..> sret([32 x i8]) initializes((0, 32)) %0, <...>) {
-                //   %7 = call [4 x double] (...) @__enzyme_fwddiff_foo(ptr @square, metadata !"enzyme_width", i64 4, <...>)
-                //   <Here we are, we want to add the following two lines>
-                //   store [4 x double] %7, ptr %0, align 8
-                //   ret void
-                // }
-
-                // now store the result of the enzyme call into the sret pointer.
-                let sret_ptr = outer_args[0];
-                let call_ty = cx.val_ty(call);
-                if attrs.width == 1 {
-                    assert_eq!(cx.type_kind(call_ty), TypeKind::Struct);
-                } else {
-                    assert_eq!(cx.type_kind(call_ty), TypeKind::Array);
-                }
-                llvm::LLVMBuildStore(&builder.llbuilder, call, sret_ptr);
-            }
-            builder.ret_void();
-        } else {
-            builder.ret(call);
-        }
-
-        // Let's crash in case that we messed something up above and generated invalid IR.
-        llvm::LLVMRustVerifyFunction(
-            outer_fn,
-            llvm::LLVMRustVerifierFailureAction::LLVMAbortProcessAction,
-        );
-    }
-}
-
-pub(crate) fn differentiate<'ll>(
-    module: &'ll ModuleCodegen<ModuleLlvm>,
-    cgcx: &CodegenContext<LlvmCodegenBackend>,
-    diff_items: Vec<AutoDiffItem>,
-) -> Result<(), FatalError> {
-    for item in &diff_items {
-        trace!("{}", item);
+    let enzyme_ty = unsafe { llvm::LLVMFunctionType(ret_ty, ptr::null(), 0, TRUE) };
+
+    // FIXME(ZuseZ4): the CC/Addr/Vis values are best effort guesses, we should look at tests and
+    // think a bit more about what should go here.
+    let cc = unsafe { llvm::LLVMGetFunctionCallConv(fn_to_diff) };
+    let ad_fn = declare_simple_fn(
+        cx,
+        &ad_name,
+        llvm::CallConv::try_from(cc).expect("invalid callconv"),
+        llvm::UnnamedAddr::No,
+        llvm::Visibility::Default,
+        enzyme_ty,
+    );
+
+    let num_args = llvm::LLVMCountParams(&fn_to_diff);
+    let mut args = Vec::with_capacity(num_args as usize + 1);
+    args.push(fn_to_diff);
+
+    let enzyme_primal_ret = cx.create_metadata(b"enzyme_primal_return");
+    if matches!(attrs.ret_activity, DiffActivity::Dual | DiffActivity::Active) {
+        args.push(cx.get_metadata_value(enzyme_primal_ret));
     }
-
-    let diag_handler = cgcx.create_dcx();
-
-    let cx = SimpleCx::new(module.module_llvm.llmod(), module.module_llvm.llcx, cgcx.pointer_size);
-
-    // First of all, did the user try to use autodiff without using the -Zautodiff=Enable flag?
-    if !diff_items.is_empty()
-        && !cgcx.opts.unstable_opts.autodiff.contains(&rustc_session::config::AutoDiff::Enable)
-    {
-        return Err(diag_handler.handle().emit_almost_fatal(AutoDiffWithoutEnable));
-    }
-
-    // Here we replace the placeholder code with the actual autodiff code, which calls Enzyme.
-    for item in diff_items.iter() {
-        let name = item.source.clone();
-        let fn_def: Option<&llvm::Value> = cx.get_function(&name);
-        let Some(fn_def) = fn_def else {
-            return Err(llvm_err(
-                diag_handler.handle(),
-                LlvmError::PrepareAutoDiff {
-                    src: item.source.clone(),
-                    target: item.target.clone(),
-                    error: "could not find source function".to_owned(),
-                },
-            ));
-        };
-        debug!(?item.target);
-        let fn_target: Option<&llvm::Value> = cx.get_function(&item.target);
-        let Some(fn_target) = fn_target else {
-            return Err(llvm_err(
-                diag_handler.handle(),
-                LlvmError::PrepareAutoDiff {
-                    src: item.source.clone(),
-                    target: item.target.clone(),
-                    error: "could not find target function".to_owned(),
-                },
-            ));
-        };
-
-        generate_enzyme_call(&cx, fn_def, fn_target, item.attrs.clone());
+    if attrs.width > 1 {
+        let enzyme_width = cx.create_metadata(b"enzyme_width");
+        args.push(cx.get_metadata_value(enzyme_width));
+        args.push(cx.get_const_int(cx.type_i64(), attrs.width as u64));
     }
 
-    // FIXME(ZuseZ4): support SanitizeHWAddress and prevent illegal/unsupported opts
+    match_args_from_caller_to_enzyme(
+        &cx,
+        builder,
+        attrs.width,
+        &mut args,
+        &attrs.input_activity,
+        fn_args,
+    );
 
-    trace!("done with differentiate()");
+    let call = builder.call(enzyme_ty, None, None, ad_fn, &args, None, None);
 
-    Ok(())
+    builder.store_to_place(call, dest.val);
 }
diff --git a/compiler/rustc_codegen_llvm/src/common.rs b/compiler/rustc_codegen_llvm/src/common.rs
index f29fefb66f0..11b79a7fe68 100644
--- a/compiler/rustc_codegen_llvm/src/common.rs
+++ b/compiler/rustc_codegen_llvm/src/common.rs
@@ -20,7 +20,7 @@ use tracing::debug;
 use crate::consts::const_alloc_to_llvm;
 pub(crate) use crate::context::CodegenCx;
 use crate::context::{GenericCx, SCx};
-use crate::llvm::{self, BasicBlock, Bool, ConstantInt, False, Metadata, True};
+use crate::llvm::{self, BasicBlock, ConstantInt, FALSE, Metadata, TRUE, ToLlvmBool};
 use crate::type_::Type;
 use crate::value::Value;
 
@@ -158,7 +158,7 @@ impl<'ll, 'tcx> ConstCodegenMethods for CodegenCx<'ll, 'tcx> {
             self.type_kind(t) == TypeKind::Integer,
             "only allows integer types in const_int"
         );
-        unsafe { llvm::LLVMConstInt(t, i as u64, True) }
+        unsafe { llvm::LLVMConstInt(t, i as u64, TRUE) }
     }
 
     fn const_u8(&self, i: u8) -> &'ll Value {
@@ -192,7 +192,7 @@ impl<'ll, 'tcx> ConstCodegenMethods for CodegenCx<'ll, 'tcx> {
             self.type_kind(t) == TypeKind::Integer,
             "only allows integer types in const_uint"
         );
-        unsafe { llvm::LLVMConstInt(t, i, False) }
+        unsafe { llvm::LLVMConstInt(t, i, FALSE) }
     }
 
     fn const_uint_big(&self, t: &'ll Type, u: u128) -> &'ll Value {
@@ -377,7 +377,7 @@ pub(crate) fn val_ty(v: &Value) -> &Type {
 pub(crate) fn bytes_in_context<'ll>(llcx: &'ll llvm::Context, bytes: &[u8]) -> &'ll Value {
     unsafe {
         let ptr = bytes.as_ptr() as *const c_char;
-        llvm::LLVMConstStringInContext2(llcx, ptr, bytes.len(), True)
+        llvm::LLVMConstStringInContext2(llcx, ptr, bytes.len(), TRUE)
     }
 }
 
@@ -392,7 +392,7 @@ fn struct_in_context<'ll>(
     packed: bool,
 ) -> &'ll Value {
     let len = c_uint::try_from(elts.len()).expect("LLVMConstStructInContext elements len overflow");
-    unsafe { llvm::LLVMConstStructInContext(llcx, elts.as_ptr(), len, packed as Bool) }
+    unsafe { llvm::LLVMConstStructInContext(llcx, elts.as_ptr(), len, packed.to_llvm_bool()) }
 }
 
 #[inline]
diff --git a/compiler/rustc_codegen_llvm/src/consts.rs b/compiler/rustc_codegen_llvm/src/consts.rs
index 6b06daf3477..9ec7b0f80ae 100644
--- a/compiler/rustc_codegen_llvm/src/consts.rs
+++ b/compiler/rustc_codegen_llvm/src/consts.rs
@@ -4,6 +4,7 @@ use rustc_abi::{Align, HasDataLayout, Primitive, Scalar, Size, WrappingRange};
 use rustc_codegen_ssa::common;
 use rustc_codegen_ssa::traits::*;
 use rustc_hir::LangItem;
+use rustc_hir::attrs::Linkage;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
 use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
@@ -11,7 +12,7 @@ use rustc_middle::mir::interpret::{
     Allocation, ConstAllocation, ErrorHandled, InitChunk, Pointer, Scalar as InterpScalar,
     read_target_uint,
 };
-use rustc_middle::mir::mono::{Linkage, MonoItem};
+use rustc_middle::mir::mono::MonoItem;
 use rustc_middle::ty::layout::{HasTypingEnv, LayoutOf};
 use rustc_middle::ty::{self, Instance};
 use rustc_middle::{bug, span_bug};
diff --git a/compiler/rustc_codegen_llvm/src/context.rs b/compiler/rustc_codegen_llvm/src/context.rs
index ee77774c688..4fd6110ac4a 100644
--- a/compiler/rustc_codegen_llvm/src/context.rs
+++ b/compiler/rustc_codegen_llvm/src/context.rs
@@ -8,7 +8,6 @@ use std::str;
 use rustc_abi::{HasDataLayout, Size, TargetDataLayout, VariantIdx};
 use rustc_codegen_ssa::back::versioned_llvm_target;
 use rustc_codegen_ssa::base::{wants_msvc_seh, wants_wasm_eh};
-use rustc_codegen_ssa::common::TypeKind;
 use rustc_codegen_ssa::errors as ssa_errors;
 use rustc_codegen_ssa::traits::*;
 use rustc_data_structures::base_n::{ALPHANUMERIC_ONLY, ToBaseN};
@@ -213,6 +212,12 @@ pub(crate) unsafe fn create_module<'ll>(
             target_data_layout = target_data_layout.replace("p8:128:128:128:48", "p8:128:128")
         }
     }
+    if llvm_version < (22, 0, 0) {
+        if sess.target.arch == "avr" {
+            // LLVM 22.0 updated the default layout on avr: https://github.com/llvm/llvm-project/pull/153010
+            target_data_layout = target_data_layout.replace("n8:16", "n8")
+        }
+    }
 
     // Ensure the data-layout values hardcoded remain the defaults.
     {
@@ -372,6 +377,15 @@ pub(crate) unsafe fn create_module<'ll>(
         }
     }
 
+    if let Some(regparm_count) = sess.opts.unstable_opts.regparm {
+        llvm::add_module_flag_u32(
+            llmod,
+            llvm::ModuleFlagMergeBehavior::Error,
+            "NumRegisterParameters",
+            regparm_count,
+        );
+    }
+
     if let Some(BranchProtection { bti, pac_ret }) = sess.opts.unstable_opts.branch_protection {
         if sess.target.arch == "aarch64" {
             llvm::add_module_flag_u32(
@@ -457,6 +471,15 @@ pub(crate) unsafe fn create_module<'ll>(
         }
     }
 
+    if sess.opts.unstable_opts.indirect_branch_cs_prefix {
+        llvm::add_module_flag_u32(
+            llmod,
+            llvm::ModuleFlagMergeBehavior::Override,
+            "indirect_branch_cs_prefix",
+            1,
+        );
+    }
+
     match (sess.opts.unstable_opts.small_data_threshold, sess.target.small_data_threshold_support())
     {
         // Set up the small-data optimization limit for architectures that use
@@ -654,10 +677,6 @@ impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> {
     }
 }
 impl<'ll> SimpleCx<'ll> {
-    pub(crate) fn get_return_type(&self, ty: &'ll Type) -> &'ll Type {
-        assert_eq!(self.type_kind(ty), TypeKind::Function);
-        unsafe { llvm::LLVMGetReturnType(ty) }
-    }
     pub(crate) fn get_type_of_global(&self, val: &'ll Value) -> &'ll Type {
         unsafe { llvm::LLVMGlobalGetValueType(val) }
     }
@@ -682,7 +701,7 @@ impl<'ll, CX: Borrow<SCx<'ll>>> GenericCx<'ll, CX> {
     }
 
     pub(crate) fn get_const_int(&self, ty: &'ll Type, val: u64) -> &'ll Value {
-        unsafe { llvm::LLVMConstInt(ty, val, llvm::False) }
+        unsafe { llvm::LLVMConstInt(ty, val, llvm::FALSE) }
     }
 
     pub(crate) fn get_const_i64(&self, n: u64) -> &'ll Value {
@@ -721,16 +740,6 @@ impl<'ll, CX: Borrow<SCx<'ll>>> GenericCx<'ll, CX> {
             llvm::LLVMMDStringInContext2(self.llcx(), name.as_ptr() as *const c_char, name.len())
         }
     }
-
-    pub(crate) fn get_functions(&self) -> Vec<&'ll Value> {
-        let mut functions = vec![];
-        let mut func = unsafe { llvm::LLVMGetFirstFunction(self.llmod()) };
-        while let Some(f) = func {
-            functions.push(f);
-            func = unsafe { llvm::LLVMGetNextFunction(f) }
-        }
-        functions
-    }
 }
 
 impl<'ll, 'tcx> MiscCodegenMethods<'tcx> for CodegenCx<'ll, 'tcx> {
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/gdb.rs b/compiler/rustc_codegen_llvm/src/debuginfo/gdb.rs
index 6eb7042da61..7a6dc008c7b 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/gdb.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/gdb.rs
@@ -72,7 +72,7 @@ pub(crate) fn get_or_insert_gdb_debug_scripts_section_global<'ll>(
                 .unwrap_or_else(|| bug!("symbol `{}` is already defined", section_var_name));
             llvm::set_section(section_var, c".debug_gdb_scripts");
             llvm::set_initializer(section_var, cx.const_bytes(section_contents));
-            llvm::LLVMSetGlobalConstant(section_var, llvm::True);
+            llvm::LLVMSetGlobalConstant(section_var, llvm::TRUE);
             llvm::set_unnamed_address(section_var, llvm::UnnamedAddr::Global);
             llvm::set_linkage(section_var, llvm::Linkage::LinkOnceODRLinkage);
             // This should make sure that the whole section is not larger than
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/metadata/type_map.rs b/compiler/rustc_codegen_llvm/src/debuginfo/metadata/type_map.rs
index d1502d2b1e6..18a783a348a 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/metadata/type_map.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/metadata/type_map.rs
@@ -276,7 +276,7 @@ pub(super) fn build_type_with_children<'ll, 'tcx>(
         && let ty::Adt(adt_def, args) = ty.kind()
     {
         let def_id = adt_def.did();
-        // If any sub type reference the original type definition and the sub type has a type
+        // If any child type references the original type definition and the child type has a type
         // parameter that strictly contains the original parameter, the original type is a recursive
         // type that can expanding indefinitely. Example,
         // ```
@@ -285,21 +285,43 @@ pub(super) fn build_type_with_children<'ll, 'tcx>(
         //     Item(T),
         // }
         // ```
-        let is_expanding_recursive = adt_def.is_enum()
-            && debug_context(cx).adt_stack.borrow().iter().any(|(parent_def_id, parent_args)| {
-                if def_id == *parent_def_id {
-                    args.iter().zip(parent_args.iter()).any(|(arg, parent_arg)| {
-                        if let (Some(arg), Some(parent_arg)) = (arg.as_type(), parent_arg.as_type())
-                        {
-                            arg != parent_arg && arg.contains(parent_arg)
-                        } else {
-                            false
-                        }
-                    })
-                } else {
-                    false
-                }
-            });
+        let is_expanding_recursive = {
+            let stack = debug_context(cx).adt_stack.borrow();
+            stack
+                .iter()
+                .enumerate()
+                .rev()
+                .skip(1)
+                .filter(|(_, (ancestor_def_id, _))| def_id == *ancestor_def_id)
+                .any(|(ancestor_index, (_, ancestor_args))| {
+                    args.iter()
+                        .zip(ancestor_args.iter())
+                        .filter_map(|(arg, ancestor_arg)| arg.as_type().zip(ancestor_arg.as_type()))
+                        .any(|(arg, ancestor_arg)|
+                            // Strictly contains.
+                            (arg != ancestor_arg && arg.contains(ancestor_arg))
+                            // Check all types between current and ancestor use the
+                            // ancestor_arg.
+                            // Otherwise, duplicate wrappers in normal recursive type may be
+                            // regarded as expanding.
+                            // ```
+                            // struct Recursive {
+                            //     a: Box<Box<Recursive>>,
+                            // }
+                            // ```
+                            // It can produce an ADT stack like this,
+                            // - Box<Recursive>
+                            // - Recursive
+                            // - Box<Box<Recursive>>
+                            && stack[ancestor_index + 1..stack.len()].iter().all(
+                                |(_, intermediate_args)|
+                                    intermediate_args
+                                        .iter()
+                                        .filter_map(|arg| arg.as_type())
+                                        .any(|mid_arg| mid_arg.contains(ancestor_arg))
+                            ))
+                })
+        };
         if is_expanding_recursive {
             // FIXME: indicate that this is an expanding recursive type in stub metadata?
             return DINodeCreationResult::new(stub_info.metadata, false);
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs b/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
index 6cbf2dbf7d3..2c3a84499ac 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
@@ -533,31 +533,26 @@ impl<'ll, 'tcx> DebugInfoCodegenMethods<'tcx> for CodegenCx<'ll, 'tcx> {
             // First, let's see if this is a method within an inherent impl. Because
             // if yes, we want to make the result subroutine DIE a child of the
             // subroutine's self-type.
-            if let Some(impl_def_id) = cx.tcx.impl_of_assoc(instance.def_id()) {
-                // If the method does *not* belong to a trait, proceed
-                if cx.tcx.trait_id_of_impl(impl_def_id).is_none() {
-                    let impl_self_ty = cx.tcx.instantiate_and_normalize_erasing_regions(
-                        instance.args,
-                        cx.typing_env(),
-                        cx.tcx.type_of(impl_def_id),
-                    );
-
-                    // Only "class" methods are generally understood by LLVM,
-                    // so avoid methods on other types (e.g., `<*mut T>::null`).
-                    if let ty::Adt(def, ..) = impl_self_ty.kind()
-                        && !def.is_box()
-                    {
-                        // Again, only create type information if full debuginfo is enabled
-                        if cx.sess().opts.debuginfo == DebugInfo::Full && !impl_self_ty.has_param()
-                        {
-                            return (type_di_node(cx, impl_self_ty), true);
-                        } else {
-                            return (namespace::item_namespace(cx, def.did()), false);
-                        }
+            // For trait method impls we still use the "parallel namespace"
+            // strategy
+            if let Some(imp_def_id) = cx.tcx.inherent_impl_of_assoc(instance.def_id()) {
+                let impl_self_ty = cx.tcx.instantiate_and_normalize_erasing_regions(
+                    instance.args,
+                    cx.typing_env(),
+                    cx.tcx.type_of(imp_def_id),
+                );
+
+                // Only "class" methods are generally understood by LLVM,
+                // so avoid methods on other types (e.g., `<*mut T>::null`).
+                if let ty::Adt(def, ..) = impl_self_ty.kind()
+                    && !def.is_box()
+                {
+                    // Again, only create type information if full debuginfo is enabled
+                    if cx.sess().opts.debuginfo == DebugInfo::Full && !impl_self_ty.has_param() {
+                        return (type_di_node(cx, impl_self_ty), true);
+                    } else {
+                        return (namespace::item_namespace(cx, def.did()), false);
                     }
-                } else {
-                    // For trait method impls we still use the "parallel namespace"
-                    // strategy
                 }
             }
 
diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/namespace.rs b/compiler/rustc_codegen_llvm/src/debuginfo/namespace.rs
index b4d639368b0..1dcf4ff3062 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/namespace.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/namespace.rs
@@ -38,7 +38,7 @@ pub(crate) fn item_namespace<'ll>(cx: &CodegenCx<'ll, '_>, def_id: DefId) -> &'l
             parent_scope,
             namespace_name_string.as_ptr(),
             namespace_name_string.len(),
-            llvm::False, // ExportSymbols (only relevant for C++ anonymous namespaces)
+            llvm::FALSE, // ExportSymbols (only relevant for C++ anonymous namespaces)
         )
     };
 
diff --git a/compiler/rustc_codegen_llvm/src/intrinsic.rs b/compiler/rustc_codegen_llvm/src/intrinsic.rs
index 7b27e496986..49d3dedbeab 100644
--- a/compiler/rustc_codegen_llvm/src/intrinsic.rs
+++ b/compiler/rustc_codegen_llvm/src/intrinsic.rs
@@ -3,24 +3,29 @@ use std::cmp::Ordering;
 
 use rustc_abi::{Align, BackendRepr, ExternAbi, Float, HasDataLayout, Primitive, Size};
 use rustc_codegen_ssa::base::{compare_simd_types, wants_msvc_seh, wants_wasm_eh};
+use rustc_codegen_ssa::codegen_attrs::autodiff_attrs;
 use rustc_codegen_ssa::common::{IntPredicate, TypeKind};
 use rustc_codegen_ssa::errors::{ExpectedPointerMutability, InvalidMonomorphization};
 use rustc_codegen_ssa::mir::operand::{OperandRef, OperandValue};
 use rustc_codegen_ssa::mir::place::{PlaceRef, PlaceValue};
 use rustc_codegen_ssa::traits::*;
-use rustc_hir as hir;
+use rustc_hir::def_id::LOCAL_CRATE;
+use rustc_hir::{self as hir};
 use rustc_middle::mir::BinOp;
 use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, HasTypingEnv, LayoutOf};
-use rustc_middle::ty::{self, GenericArgsRef, Ty};
+use rustc_middle::ty::{self, GenericArgsRef, Instance, Ty, TyCtxt, TypingEnv};
 use rustc_middle::{bug, span_bug};
 use rustc_span::{Span, Symbol, sym};
-use rustc_symbol_mangling::mangle_internal_symbol;
+use rustc_symbol_mangling::{mangle_internal_symbol, symbol_name_for_instance_in_crate};
+use rustc_target::callconv::PassMode;
 use rustc_target::spec::PanicStrategy;
 use tracing::debug;
 
 use crate::abi::FnAbiLlvmExt;
 use crate::builder::Builder;
+use crate::builder::autodiff::{adjust_activity_to_abi, generate_enzyme_call};
 use crate::context::CodegenCx;
+use crate::errors::AutoDiffWithoutEnable;
 use crate::llvm::{self, Metadata};
 use crate::type_::Type;
 use crate::type_of::LayoutLlvmExt;
@@ -189,6 +194,10 @@ impl<'ll, 'tcx> IntrinsicCallBuilderMethods<'tcx> for Builder<'_, 'll, 'tcx> {
                     &[ptr, args[1].immediate()],
                 )
             }
+            sym::autodiff => {
+                codegen_autodiff(self, tcx, instance, args, result);
+                return Ok(());
+            }
             sym::is_val_statically_known => {
                 if let OperandValue::Immediate(imm) = args[0].val {
                     self.call_intrinsic(
@@ -321,10 +330,16 @@ impl<'ll, 'tcx> IntrinsicCallBuilderMethods<'tcx> for Builder<'_, 'll, 'tcx> {
                     _ => bug!(),
                 };
                 let ptr = args[0].immediate();
+                let locality = fn_args.const_at(1).to_value().valtree.unwrap_leaf().to_i32();
                 self.call_intrinsic(
                     "llvm.prefetch",
                     &[self.val_ty(ptr)],
-                    &[ptr, self.const_i32(rw), args[1].immediate(), self.const_i32(cache_type)],
+                    &[
+                        ptr,
+                        self.const_i32(rw),
+                        self.const_i32(locality),
+                        self.const_i32(cache_type),
+                    ],
                 )
             }
             sym::carrying_mul_add => {
@@ -1113,6 +1128,143 @@ fn get_rust_try_fn<'a, 'll, 'tcx>(
     rust_try
 }
 
+fn codegen_autodiff<'ll, 'tcx>(
+    bx: &mut Builder<'_, 'll, 'tcx>,
+    tcx: TyCtxt<'tcx>,
+    instance: ty::Instance<'tcx>,
+    args: &[OperandRef<'tcx, &'ll Value>],
+    result: PlaceRef<'tcx, &'ll Value>,
+) {
+    if !tcx.sess.opts.unstable_opts.autodiff.contains(&rustc_session::config::AutoDiff::Enable) {
+        let _ = tcx.dcx().emit_almost_fatal(AutoDiffWithoutEnable);
+    }
+
+    let fn_args = instance.args;
+    let callee_ty = instance.ty(tcx, bx.typing_env());
+
+    let sig = callee_ty.fn_sig(tcx).skip_binder();
+
+    let ret_ty = sig.output();
+    let llret_ty = bx.layout_of(ret_ty).llvm_type(bx);
+
+    // Get source, diff, and attrs
+    let (source_id, source_args) = match fn_args.into_type_list(tcx)[0].kind() {
+        ty::FnDef(def_id, source_params) => (def_id, source_params),
+        _ => bug!("invalid autodiff intrinsic args"),
+    };
+
+    let fn_source = match Instance::try_resolve(tcx, bx.cx.typing_env(), *source_id, source_args) {
+        Ok(Some(instance)) => instance,
+        Ok(None) => bug!(
+            "could not resolve ({:?}, {:?}) to a specific autodiff instance",
+            source_id,
+            source_args
+        ),
+        Err(_) => {
+            // An error has already been emitted
+            return;
+        }
+    };
+
+    let source_symbol = symbol_name_for_instance_in_crate(tcx, fn_source.clone(), LOCAL_CRATE);
+    let Some(fn_to_diff) = bx.cx.get_function(&source_symbol) else {
+        bug!("could not find source function")
+    };
+
+    let (diff_id, diff_args) = match fn_args.into_type_list(tcx)[1].kind() {
+        ty::FnDef(def_id, diff_args) => (def_id, diff_args),
+        _ => bug!("invalid args"),
+    };
+
+    let fn_diff = match Instance::try_resolve(tcx, bx.cx.typing_env(), *diff_id, diff_args) {
+        Ok(Some(instance)) => instance,
+        Ok(None) => bug!(
+            "could not resolve ({:?}, {:?}) to a specific autodiff instance",
+            diff_id,
+            diff_args
+        ),
+        Err(_) => {
+            // An error has already been emitted
+            return;
+        }
+    };
+
+    let val_arr = get_args_from_tuple(bx, args[2], fn_diff);
+    let diff_symbol = symbol_name_for_instance_in_crate(tcx, fn_diff.clone(), LOCAL_CRATE);
+
+    let Some(mut diff_attrs) = autodiff_attrs(tcx, fn_diff.def_id()) else {
+        bug!("could not find autodiff attrs")
+    };
+
+    adjust_activity_to_abi(
+        tcx,
+        fn_source.ty(tcx, TypingEnv::fully_monomorphized()),
+        &mut diff_attrs.input_activity,
+    );
+
+    // Build body
+    generate_enzyme_call(
+        bx,
+        bx.cx,
+        fn_to_diff,
+        &diff_symbol,
+        llret_ty,
+        &val_arr,
+        diff_attrs.clone(),
+        result,
+    );
+}
+
+fn get_args_from_tuple<'ll, 'tcx>(
+    bx: &mut Builder<'_, 'll, 'tcx>,
+    tuple_op: OperandRef<'tcx, &'ll Value>,
+    fn_instance: Instance<'tcx>,
+) -> Vec<&'ll Value> {
+    let cx = bx.cx;
+    let fn_abi = cx.fn_abi_of_instance(fn_instance, ty::List::empty());
+
+    match tuple_op.val {
+        OperandValue::Immediate(val) => vec![val],
+        OperandValue::Pair(v1, v2) => vec![v1, v2],
+        OperandValue::Ref(ptr) => {
+            let tuple_place = PlaceRef { val: ptr, layout: tuple_op.layout };
+
+            let mut result = Vec::with_capacity(fn_abi.args.len());
+            let mut tuple_index = 0;
+
+            for arg in &fn_abi.args {
+                match arg.mode {
+                    PassMode::Ignore => {}
+                    PassMode::Direct(_) | PassMode::Cast { .. } => {
+                        let field = tuple_place.project_field(bx, tuple_index);
+                        let llvm_ty = field.layout.llvm_type(bx.cx);
+                        let val = bx.load(llvm_ty, field.val.llval, field.val.align);
+                        result.push(val);
+                        tuple_index += 1;
+                    }
+                    PassMode::Pair(_, _) => {
+                        let field = tuple_place.project_field(bx, tuple_index);
+                        let llvm_ty = field.layout.llvm_type(bx.cx);
+                        let pair_val = bx.load(llvm_ty, field.val.llval, field.val.align);
+                        result.push(bx.extract_value(pair_val, 0));
+                        result.push(bx.extract_value(pair_val, 1));
+                        tuple_index += 1;
+                    }
+                    PassMode::Indirect { .. } => {
+                        let field = tuple_place.project_field(bx, tuple_index);
+                        result.push(field.val.llval);
+                        tuple_index += 1;
+                    }
+                }
+            }
+
+            result
+        }
+
+        OperandValue::ZeroSized => vec![],
+    }
+}
+
 fn generic_simd_intrinsic<'ll, 'tcx>(
     bx: &mut Builder<'_, 'll, 'tcx>,
     name: Symbol,
diff --git a/compiler/rustc_codegen_llvm/src/lib.rs b/compiler/rustc_codegen_llvm/src/lib.rs
index ca84b6de8b1..628cb34fd9e 100644
--- a/compiler/rustc_codegen_llvm/src/lib.rs
+++ b/compiler/rustc_codegen_llvm/src/lib.rs
@@ -30,7 +30,6 @@ use context::SimpleCx;
 use errors::ParseTargetMachineConfig;
 use llvm_util::target_config;
 use rustc_ast::expand::allocator::AllocatorKind;
-use rustc_ast::expand::autodiff_attrs::AutoDiffItem;
 use rustc_codegen_ssa::back::lto::{SerializedModule, ThinModule};
 use rustc_codegen_ssa::back::write::{
     CodegenContext, FatLtoInput, ModuleConfig, TargetMachineFactoryConfig, TargetMachineFactoryFn,
@@ -38,7 +37,7 @@ use rustc_codegen_ssa::back::write::{
 use rustc_codegen_ssa::traits::*;
 use rustc_codegen_ssa::{CodegenResults, CompiledModule, ModuleCodegen, TargetConfig};
 use rustc_data_structures::fx::FxIndexMap;
-use rustc_errors::{DiagCtxtHandle, FatalError};
+use rustc_errors::DiagCtxtHandle;
 use rustc_metadata::EncodedMetadata;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
 use rustc_middle::ty::TyCtxt;
@@ -47,18 +46,11 @@ use rustc_session::Session;
 use rustc_session::config::{OptLevel, OutputFilenames, PrintKind, PrintRequest};
 use rustc_span::Symbol;
 
-mod back {
-    pub(crate) mod archive;
-    pub(crate) mod lto;
-    pub(crate) mod owned_target_machine;
-    mod profiling;
-    pub(crate) mod write;
-}
-
 mod abi;
 mod allocator;
 mod asm;
 mod attributes;
+mod back;
 mod base;
 mod builder;
 mod callee;
@@ -173,20 +165,15 @@ impl WriteBackendMethods for LlvmCodegenBackend {
         exported_symbols_for_lto: &[String],
         each_linked_rlib_for_lto: &[PathBuf],
         modules: Vec<FatLtoInput<Self>>,
-        diff_fncs: Vec<AutoDiffItem>,
-    ) -> Result<ModuleCodegen<Self::Module>, FatalError> {
+    ) -> ModuleCodegen<Self::Module> {
         let mut module =
-            back::lto::run_fat(cgcx, exported_symbols_for_lto, each_linked_rlib_for_lto, modules)?;
-
-        if !diff_fncs.is_empty() {
-            builder::autodiff::differentiate(&module, cgcx, diff_fncs)?;
-        }
+            back::lto::run_fat(cgcx, exported_symbols_for_lto, each_linked_rlib_for_lto, modules);
 
         let dcx = cgcx.create_dcx();
         let dcx = dcx.handle();
-        back::lto::run_pass_manager(cgcx, dcx, &mut module, false)?;
+        back::lto::run_pass_manager(cgcx, dcx, &mut module, false);
 
-        Ok(module)
+        module
     }
     fn run_thin_lto(
         cgcx: &CodegenContext<Self>,
@@ -194,7 +181,7 @@ impl WriteBackendMethods for LlvmCodegenBackend {
         each_linked_rlib_for_lto: &[PathBuf],
         modules: Vec<(String, Self::ThinBuffer)>,
         cached_modules: Vec<(SerializedModule<Self::ModuleBuffer>, WorkProduct)>,
-    ) -> Result<(Vec<ThinModule<Self>>, Vec<WorkProduct>), FatalError> {
+    ) -> (Vec<ThinModule<Self>>, Vec<WorkProduct>) {
         back::lto::run_thin(
             cgcx,
             exported_symbols_for_lto,
@@ -208,20 +195,20 @@ impl WriteBackendMethods for LlvmCodegenBackend {
         dcx: DiagCtxtHandle<'_>,
         module: &mut ModuleCodegen<Self::Module>,
         config: &ModuleConfig,
-    ) -> Result<(), FatalError> {
+    ) {
         back::write::optimize(cgcx, dcx, module, config)
     }
     fn optimize_thin(
         cgcx: &CodegenContext<Self>,
         thin: ThinModule<Self>,
-    ) -> Result<ModuleCodegen<Self::Module>, FatalError> {
+    ) -> ModuleCodegen<Self::Module> {
         back::lto::optimize_thin_module(thin, cgcx)
     }
     fn codegen(
         cgcx: &CodegenContext<Self>,
         module: ModuleCodegen<Self::Module>,
         config: &ModuleConfig,
-    ) -> Result<CompiledModule, FatalError> {
+    ) -> CompiledModule {
         back::write::codegen(cgcx, module, config)
     }
     fn prepare_thin(
@@ -420,12 +407,12 @@ impl ModuleLlvm {
         cgcx: &CodegenContext<LlvmCodegenBackend>,
         name: &str,
         dcx: DiagCtxtHandle<'_>,
-    ) -> Result<OwnedTargetMachine, FatalError> {
+    ) -> OwnedTargetMachine {
         let tm_factory_config = TargetMachineFactoryConfig::new(cgcx, name);
         match (cgcx.tm_factory)(tm_factory_config) {
-            Ok(m) => Ok(m),
+            Ok(m) => m,
             Err(e) => {
-                return Err(dcx.emit_almost_fatal(ParseTargetMachineConfig(e)));
+                dcx.emit_fatal(ParseTargetMachineConfig(e));
             }
         }
     }
@@ -435,13 +422,13 @@ impl ModuleLlvm {
         name: &CStr,
         buffer: &[u8],
         dcx: DiagCtxtHandle<'_>,
-    ) -> Result<Self, FatalError> {
+    ) -> Self {
         unsafe {
             let llcx = llvm::LLVMRustContextCreate(cgcx.fewer_names);
-            let llmod_raw = back::lto::parse_module(llcx, name, buffer, dcx)?;
-            let tm = ModuleLlvm::tm_from_cgcx(cgcx, name.to_str().unwrap(), dcx)?;
+            let llmod_raw = back::lto::parse_module(llcx, name, buffer, dcx);
+            let tm = ModuleLlvm::tm_from_cgcx(cgcx, name.to_str().unwrap(), dcx);
 
-            Ok(ModuleLlvm { llmod_raw, llcx, tm: ManuallyDrop::new(tm) })
+            ModuleLlvm { llmod_raw, llcx, tm: ManuallyDrop::new(tm) }
         }
     }
 
diff --git a/compiler/rustc_codegen_llvm/src/llvm/archive_ro.rs b/compiler/rustc_codegen_llvm/src/llvm/archive_ro.rs
deleted file mode 100644
index 51bcc4d123d..00000000000
--- a/compiler/rustc_codegen_llvm/src/llvm/archive_ro.rs
+++ /dev/null
@@ -1,94 +0,0 @@
-//! A wrapper around LLVM's archive (.a) code
-
-use std::path::Path;
-use std::{slice, str};
-
-use rustc_fs_util::path_to_c_string;
-
-pub(crate) struct ArchiveRO {
-    pub raw: &'static mut super::Archive,
-}
-
-unsafe impl Send for ArchiveRO {}
-
-pub(crate) struct Iter<'a> {
-    raw: &'a mut super::ArchiveIterator<'a>,
-}
-
-pub(crate) struct Child<'a> {
-    pub raw: &'a mut super::ArchiveChild<'a>,
-}
-
-impl ArchiveRO {
-    /// Opens a static archive for read-only purposes. This is more optimized
-    /// than the `open` method because it uses LLVM's internal `Archive` class
-    /// rather than shelling out to `ar` for everything.
-    ///
-    /// If this archive is used with a mutable method, then an error will be
-    /// raised.
-    pub(crate) fn open(dst: &Path) -> Result<ArchiveRO, String> {
-        unsafe {
-            let s = path_to_c_string(dst);
-            let ar = super::LLVMRustOpenArchive(s.as_ptr()).ok_or_else(|| {
-                super::last_error().unwrap_or_else(|| "failed to open archive".to_owned())
-            })?;
-            Ok(ArchiveRO { raw: ar })
-        }
-    }
-
-    pub(crate) fn iter(&self) -> Iter<'_> {
-        unsafe { Iter { raw: super::LLVMRustArchiveIteratorNew(self.raw) } }
-    }
-}
-
-impl Drop for ArchiveRO {
-    fn drop(&mut self) {
-        unsafe {
-            super::LLVMRustDestroyArchive(&mut *(self.raw as *mut _));
-        }
-    }
-}
-
-impl<'a> Iterator for Iter<'a> {
-    type Item = Result<Child<'a>, String>;
-
-    fn next(&mut self) -> Option<Result<Child<'a>, String>> {
-        unsafe {
-            match super::LLVMRustArchiveIteratorNext(self.raw) {
-                Some(raw) => Some(Ok(Child { raw })),
-                None => super::last_error().map(Err),
-            }
-        }
-    }
-}
-
-impl<'a> Drop for Iter<'a> {
-    fn drop(&mut self) {
-        unsafe {
-            super::LLVMRustArchiveIteratorFree(&mut *(self.raw as *mut _));
-        }
-    }
-}
-
-impl<'a> Child<'a> {
-    pub(crate) fn name(&self) -> Option<&'a str> {
-        unsafe {
-            let mut name_len = 0;
-            let name_ptr = super::LLVMRustArchiveChildName(self.raw, &mut name_len);
-            if name_ptr.is_null() {
-                None
-            } else {
-                let name = slice::from_raw_parts(name_ptr as *const u8, name_len as usize);
-                str::from_utf8(name).ok().map(|s| s.trim())
-            }
-        }
-    }
-}
-
-impl<'a> Drop for Child<'a> {
-    fn drop(&mut self) {
-        unsafe {
-            super::LLVMRustArchiveChildFree(&mut *(self.raw as *mut _));
-        }
-    }
-}
diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
index 75d3d27f74e..ba590851dbd 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
@@ -11,9 +11,8 @@
 //! the need for an extra cast from `*const u8` on the Rust side.
 
 #![allow(non_camel_case_types)]
-#![allow(non_upper_case_globals)]
 
-use std::fmt::Debug;
+use std::fmt::{self, Debug};
 use std::marker::PhantomData;
 use std::num::NonZero;
 use std::ptr;
@@ -33,10 +32,59 @@ use crate::llvm;
 
 /// In the LLVM-C API, boolean values are passed as `typedef int LLVMBool`,
 /// which has a different ABI from Rust or C++ `bool`.
-pub(crate) type Bool = c_int;
+///
+/// This wrapper does not implement `PartialEq`.
+/// To test the underlying boolean value, use [`Self::is_true`].
+#[derive(Clone, Copy)]
+#[repr(transparent)]
+pub(crate) struct Bool {
+    value: c_int,
+}
+
+pub(crate) const TRUE: Bool = Bool::TRUE;
+pub(crate) const FALSE: Bool = Bool::FALSE;
+
+impl Bool {
+    pub(crate) const TRUE: Self = Self { value: 1 };
+    pub(crate) const FALSE: Self = Self { value: 0 };
+
+    pub(crate) const fn from_bool(rust_bool: bool) -> Self {
+        if rust_bool { Self::TRUE } else { Self::FALSE }
+    }
+
+    /// Converts this LLVM-C boolean to a Rust `bool`
+    pub(crate) fn is_true(self) -> bool {
+        // Since we're interacting with a C API, follow the C convention of
+        // treating any nonzero value as true.
+        self.value != Self::FALSE.value
+    }
+}
 
-pub(crate) const True: Bool = 1 as Bool;
-pub(crate) const False: Bool = 0 as Bool;
+impl Debug for Bool {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self.value {
+            0 => f.write_str("FALSE"),
+            1 => f.write_str("TRUE"),
+            // As with `Self::is_true`, treat any nonzero value as true.
+            v => write!(f, "TRUE ({v})"),
+        }
+    }
+}
+
+/// Convenience trait to convert `bool` to `llvm::Bool` with an explicit method call.
+///
+/// Being able to write `b.to_llvm_bool()` is less noisy than `llvm::Bool::from(b)`,
+/// while being more explicit and less mistake-prone than something like `b.into()`.
+pub(crate) trait ToLlvmBool: Copy {
+    fn to_llvm_bool(self) -> llvm::Bool;
+}
+
+impl ToLlvmBool for bool {
+    #[inline(always)]
+    fn to_llvm_bool(self) -> llvm::Bool {
+        llvm::Bool::from_bool(self)
+    }
+}
 
 /// Wrapper for a raw enum value returned from LLVM's C APIs.
 ///
@@ -97,6 +145,7 @@ pub(crate) enum ModuleFlagMergeBehavior {
 
 // Consts for the LLVM CallConv type, pre-cast to usize.
 
+/// Must match the layout of `LLVMTailCallKind`.
 #[derive(Copy, Clone, PartialEq, Debug)]
 #[repr(C)]
 #[allow(dead_code)]
@@ -214,7 +263,7 @@ pub(crate) enum AttributeKind {
     MinSize = 4,
     Naked = 5,
     NoAlias = 6,
-    NoCapture = 7,
+    CapturesAddress = 7,
     NoInline = 8,
     NonNull = 9,
     NoRedZone = 10,
@@ -249,6 +298,8 @@ pub(crate) enum AttributeKind {
     FnRetThunkExtern = 41,
     Writable = 42,
     DeadOnUnwind = 43,
+    DeadOnReturn = 44,
+    CapturesReadOnly = 45,
 }
 
 /// LLVMIntPredicate
@@ -331,10 +382,15 @@ impl RealPredicate {
     }
 }
 
-/// LLVMTypeKind
-#[derive(Copy, Clone, PartialEq, Debug)]
+/// Must match the layout of `LLVMTypeKind`.
+///
+/// Use [`RawEnum<TypeKind>`] for values of `LLVMTypeKind` returned from LLVM,
+/// to avoid risk of UB if LLVM adds new enum values.
+///
+/// All of LLVM's variants should be declared here, even if no Rust-side code refers
+/// to them, because unknown variants will cause [`RawEnum::to_rust`] to panic.
+#[derive(Copy, Clone, PartialEq, Debug, TryFromU32)]
 #[repr(C)]
-#[expect(dead_code, reason = "Some variants are unused, but are kept to match LLVM-C")]
 pub(crate) enum TypeKind {
     Void = 0,
     Half = 1,
@@ -609,17 +665,6 @@ pub(crate) enum DiagnosticLevel {
     Remark,
 }
 
-/// LLVMRustArchiveKind
-#[derive(Copy, Clone)]
-#[repr(C)]
-pub(crate) enum ArchiveKind {
-    K_GNU,
-    K_BSD,
-    K_DARWIN,
-    K_COFF,
-    K_AIXBIG,
-}
-
 unsafe extern "C" {
     // LLVMRustThinLTOData
     pub(crate) type ThinLTOData;
@@ -768,19 +813,12 @@ pub(crate) struct Builder<'a>(InvariantOpaque<'a>);
 pub(crate) struct PassManager<'a>(InvariantOpaque<'a>);
 unsafe extern "C" {
     pub type TargetMachine;
-    pub(crate) type Archive;
 }
-#[repr(C)]
-pub(crate) struct ArchiveIterator<'a>(InvariantOpaque<'a>);
-#[repr(C)]
-pub(crate) struct ArchiveChild<'a>(InvariantOpaque<'a>);
 unsafe extern "C" {
     pub(crate) type Twine;
     pub(crate) type DiagnosticInfo;
     pub(crate) type SMDiagnostic;
 }
-#[repr(C)]
-pub(crate) struct RustArchiveMember<'a>(InvariantOpaque<'a>);
 /// Opaque pointee of `LLVMOperandBundleRef`.
 #[repr(C)]
 pub(crate) struct OperandBundle<'a>(InvariantOpaque<'a>);
@@ -1045,6 +1083,8 @@ unsafe extern "C" {
         CanThrow: llvm::Bool,
     ) -> &'ll Value;
 
+    pub(crate) safe fn LLVMGetTypeKind(Ty: &Type) -> RawEnum<TypeKind>;
+
     // Operations on integer types
     pub(crate) fn LLVMInt1TypeInContext(C: &Context) -> &Type;
     pub(crate) fn LLVMInt8TypeInContext(C: &Context) -> &Type;
@@ -1196,7 +1236,7 @@ unsafe extern "C" {
     pub(crate) safe fn LLVMIsGlobalConstant(GlobalVar: &Value) -> Bool;
     pub(crate) safe fn LLVMSetGlobalConstant(GlobalVar: &Value, IsConstant: Bool);
     pub(crate) safe fn LLVMSetTailCall(CallInst: &Value, IsTailCall: Bool);
-    pub(crate) safe fn LLVMRustSetTailCallKind(CallInst: &Value, Kind: TailCallKind);
+    pub(crate) safe fn LLVMSetTailCallKind(CallInst: &Value, kind: TailCallKind);
 
     // Operations on attributes
     pub(crate) fn LLVMCreateStringAttribute(
@@ -1840,9 +1880,6 @@ unsafe extern "C" {
     // Create and destroy contexts.
     pub(crate) fn LLVMRustContextCreate(shouldDiscardNames: bool) -> &'static mut Context;
 
-    /// See llvm::LLVMTypeKind::getTypeID.
-    pub(crate) fn LLVMRustGetTypeKind(Ty: &Type) -> TypeKind;
-
     // Operations on all values
     pub(crate) fn LLVMRustGlobalAddMetadata<'a>(
         Val: &'a Value,
@@ -1892,11 +1929,17 @@ unsafe extern "C" {
         C: &Context,
         effects: MemoryEffects,
     ) -> &Attribute;
+    /// ## Safety
+    /// - Each of `LowerWords` and `UpperWords` must point to an array that is
+    ///   long enough to fully define an integer of size `NumBits`, i.e. each
+    ///   pointer must point to `NumBits.div_ceil(64)` elements or more.
+    /// - The implementation will make its own copy of the pointed-to `u64`
+    ///   values, so the pointers only need to outlive this function call.
     pub(crate) fn LLVMRustCreateRangeAttribute(
         C: &Context,
-        num_bits: c_uint,
-        lower_words: *const u64,
-        upper_words: *const u64,
+        NumBits: c_uint,
+        LowerWords: *const u64,
+        UpperWords: *const u64,
     ) -> &Attribute;
 
     // Operations on functions
@@ -2437,7 +2480,7 @@ unsafe extern "C" {
         OutputObjFile: *const c_char,
         DebugInfoCompression: *const c_char,
         UseEmulatedTls: bool,
-        ArgsCstrBuff: *const c_char,
+        ArgsCstrBuff: *const c_uchar, // See "PTR_LEN_STR".
         ArgsCstrBuffLen: usize,
         UseWasmEH: bool,
     ) -> *mut TargetMachine;
@@ -2504,19 +2547,6 @@ unsafe extern "C" {
     pub(crate) fn LLVMRustSetNormalizedTarget(M: &Module, triple: *const c_char);
     pub(crate) fn LLVMRustRunRestrictionPass(M: &Module, syms: *const *const c_char, len: size_t);
 
-    pub(crate) fn LLVMRustOpenArchive(path: *const c_char) -> Option<&'static mut Archive>;
-    pub(crate) fn LLVMRustArchiveIteratorNew(AR: &Archive) -> &mut ArchiveIterator<'_>;
-    pub(crate) fn LLVMRustArchiveIteratorNext<'a>(
-        AIR: &ArchiveIterator<'a>,
-    ) -> Option<&'a mut ArchiveChild<'a>>;
-    pub(crate) fn LLVMRustArchiveChildName(
-        ACR: &ArchiveChild<'_>,
-        size: &mut size_t,
-    ) -> *const c_char;
-    pub(crate) fn LLVMRustArchiveChildFree<'a>(ACR: &'a mut ArchiveChild<'a>);
-    pub(crate) fn LLVMRustArchiveIteratorFree<'a>(AIR: &'a mut ArchiveIterator<'a>);
-    pub(crate) fn LLVMRustDestroyArchive(AR: &'static mut Archive);
-
     pub(crate) fn LLVMRustWriteTwineToString(T: &Twine, s: &RustString);
 
     pub(crate) fn LLVMRustUnpackOptimizationDiagnostic<'a>(
@@ -2554,21 +2584,6 @@ unsafe extern "C" {
         num_ranges: &mut usize,
     ) -> bool;
 
-    pub(crate) fn LLVMRustWriteArchive(
-        Dst: *const c_char,
-        NumMembers: size_t,
-        Members: *const &RustArchiveMember<'_>,
-        WriteSymbtab: bool,
-        Kind: ArchiveKind,
-        isEC: bool,
-    ) -> LLVMRustResult;
-    pub(crate) fn LLVMRustArchiveMemberNew<'a>(
-        Filename: *const c_char,
-        Name: *const c_char,
-        Child: Option<&ArchiveChild<'a>>,
-    ) -> &'a mut RustArchiveMember<'a>;
-    pub(crate) fn LLVMRustArchiveMemberFree<'a>(Member: &'a mut RustArchiveMember<'a>);
-
     pub(crate) fn LLVMRustSetDataLayoutFromTargetMachine<'a>(M: &'a Module, TM: &'a TargetMachine);
 
     pub(crate) fn LLVMRustPositionBuilderPastAllocas<'a>(B: &Builder<'a>, Fn: &'a Value);
diff --git a/compiler/rustc_codegen_llvm/src/llvm/mod.rs b/compiler/rustc_codegen_llvm/src/llvm/mod.rs
index 154ba4fd690..d6974e22c85 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/mod.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/mod.rs
@@ -3,7 +3,6 @@
 use std::ffi::{CStr, CString};
 use std::num::NonZero;
 use std::ptr;
-use std::str::FromStr;
 use std::string::FromUtf8Error;
 
 use libc::c_uint;
@@ -16,7 +15,6 @@ pub(crate) use self::MetadataType::*;
 pub(crate) use self::ffi::*;
 use crate::common::AsCCharPtr;
 
-pub(crate) mod archive_ro;
 pub(crate) mod diagnostic;
 pub(crate) mod enzyme_ffi;
 mod ffi;
@@ -42,32 +40,6 @@ pub(crate) fn AddFunctionAttributes<'ll>(
     }
 }
 
-pub(crate) fn HasAttributeAtIndex<'ll>(
-    llfn: &'ll Value,
-    idx: AttributePlace,
-    kind: AttributeKind,
-) -> bool {
-    unsafe { LLVMRustHasAttributeAtIndex(llfn, idx.as_uint(), kind) }
-}
-
-pub(crate) fn HasStringAttribute<'ll>(llfn: &'ll Value, name: &str) -> bool {
-    unsafe { LLVMRustHasFnAttribute(llfn, name.as_c_char_ptr(), name.len()) }
-}
-
-pub(crate) fn RemoveStringAttrFromFn<'ll>(llfn: &'ll Value, name: &str) {
-    unsafe { LLVMRustRemoveFnAttribute(llfn, name.as_c_char_ptr(), name.len()) }
-}
-
-pub(crate) fn RemoveRustEnumAttributeAtIndex(
-    llfn: &Value,
-    place: AttributePlace,
-    kind: AttributeKind,
-) {
-    unsafe {
-        LLVMRustRemoveEnumAttributeAtIndex(llfn, place.as_uint(), kind);
-    }
-}
-
 pub(crate) fn AddCallSiteAttributes<'ll>(
     callsite: &'ll Value,
     idx: AttributePlace,
@@ -140,16 +112,26 @@ pub(crate) fn CreateAllocKindAttr(llcx: &Context, kind_arg: AllocKindFlags) -> &
 
 pub(crate) fn CreateRangeAttr(llcx: &Context, size: Size, range: WrappingRange) -> &Attribute {
     let lower = range.start;
+    // LLVM treats the upper bound as exclusive, but allows wrapping.
     let upper = range.end.wrapping_add(1);
-    let lower_words = [lower as u64, (lower >> 64) as u64];
-    let upper_words = [upper as u64, (upper >> 64) as u64];
+
+    // Pass each `u128` endpoint value as a `[u64; 2]` array, least-significant part first.
+    let as_u64_array = |x: u128| [x as u64, (x >> 64) as u64];
+    let lower_words: [u64; 2] = as_u64_array(lower);
+    let upper_words: [u64; 2] = as_u64_array(upper);
+
+    // To ensure that LLVM doesn't try to read beyond the `[u64; 2]` arrays,
+    // we must explicitly check that `size_bits` does not exceed 128.
+    let size_bits = size.bits();
+    assert!(size_bits <= 128);
+    // More robust assertions that are redundant with `size_bits <= 128` and
+    // should be optimized away.
+    assert!(size_bits.div_ceil(64) <= u64::try_from(lower_words.len()).unwrap());
+    assert!(size_bits.div_ceil(64) <= u64::try_from(upper_words.len()).unwrap());
+    let size_bits = c_uint::try_from(size_bits).unwrap();
+
     unsafe {
-        LLVMRustCreateRangeAttribute(
-            llcx,
-            size.bits().try_into().unwrap(),
-            lower_words.as_ptr(),
-            upper_words.as_ptr(),
-        )
+        LLVMRustCreateRangeAttribute(llcx, size_bits, lower_words.as_ptr(), upper_words.as_ptr())
     }
 }
 
@@ -178,21 +160,6 @@ pub(crate) enum CodeGenOptSize {
     CodeGenOptSizeAggressive = 2,
 }
 
-impl FromStr for ArchiveKind {
-    type Err = ();
-
-    fn from_str(s: &str) -> Result<Self, Self::Err> {
-        match s {
-            "gnu" => Ok(ArchiveKind::K_GNU),
-            "bsd" => Ok(ArchiveKind::K_BSD),
-            "darwin" => Ok(ArchiveKind::K_DARWIN),
-            "coff" => Ok(ArchiveKind::K_COFF),
-            "aix_big" => Ok(ArchiveKind::K_AIXBIG),
-            _ => Err(()),
-        }
-    }
-}
-
 pub(crate) fn SetInstructionCallConv(instr: &Value, cc: CallConv) {
     unsafe {
         LLVMSetInstructionCallConv(instr, cc as c_uint);
@@ -258,7 +225,7 @@ pub(crate) fn set_initializer(llglobal: &Value, constant_val: &Value) {
 }
 
 pub(crate) fn set_global_constant(llglobal: &Value, is_constant: bool) {
-    LLVMSetGlobalConstant(llglobal, if is_constant { ffi::True } else { ffi::False });
+    LLVMSetGlobalConstant(llglobal, is_constant.to_llvm_bool());
 }
 
 pub(crate) fn get_linkage(llglobal: &Value) -> Linkage {
@@ -272,7 +239,7 @@ pub(crate) fn set_linkage(llglobal: &Value, linkage: Linkage) {
 }
 
 pub(crate) fn is_declaration(llglobal: &Value) -> bool {
-    unsafe { LLVMIsDeclaration(llglobal) == ffi::True }
+    unsafe { LLVMIsDeclaration(llglobal) }.is_true()
 }
 
 pub(crate) fn get_visibility(llglobal: &Value) -> Visibility {
diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
index 28d2100f478..d927ffd78c2 100644
--- a/compiler/rustc_codegen_llvm/src/llvm_util.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -26,7 +26,7 @@ static INIT: Once = Once::new();
 pub(crate) fn init(sess: &Session) {
     unsafe {
         // Before we touch LLVM, make sure that multithreading is enabled.
-        if llvm::LLVMIsMultithreaded() != 1 {
+        if !llvm::LLVMIsMultithreaded().is_true() {
             bug!("LLVM compiled without support for threads");
         }
         INIT.call_once(|| {
@@ -277,8 +277,9 @@ pub(crate) fn to_llvm_features<'a>(sess: &Session, s: &'a str) -> Option<LLVMFea
         {
             None
         }
+        ("loongarch32" | "loongarch64", "32s") if get_version().0 < 21 => None,
         // Filter out features that are not supported by the current LLVM version
-        ("riscv32" | "riscv64", "zacas") if get_version().0 < 20 => None,
+        ("riscv32" | "riscv64", "zacas" | "rva23u64" | "supm") if get_version().0 < 20 => None,
         (
             "s390x",
             "message-security-assist-extension12"
diff --git a/compiler/rustc_codegen_llvm/src/mono_item.rs b/compiler/rustc_codegen_llvm/src/mono_item.rs
index f9edaded60d..52eefe2d4d2 100644
--- a/compiler/rustc_codegen_llvm/src/mono_item.rs
+++ b/compiler/rustc_codegen_llvm/src/mono_item.rs
@@ -1,8 +1,9 @@
 use rustc_codegen_ssa::traits::*;
+use rustc_hir::attrs::Linkage;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
 use rustc_middle::bug;
-use rustc_middle::mir::mono::{Linkage, Visibility};
+use rustc_middle::mir::mono::Visibility;
 use rustc_middle::ty::layout::{FnAbiOf, HasTypingEnv, LayoutOf};
 use rustc_middle::ty::{self, Instance, TypeVisitableExt};
 use rustc_session::config::CrateType;
@@ -132,7 +133,7 @@ impl CodegenCx<'_, '_> {
 
         // Thread-local variables generally don't support copy relocations.
         let is_thread_local_var = llvm::LLVMIsAGlobalVariable(llval)
-            .is_some_and(|v| llvm::LLVMIsThreadLocal(v) == llvm::True);
+            .is_some_and(|v| llvm::LLVMIsThreadLocal(v).is_true());
         if is_thread_local_var {
             return false;
         }
diff --git a/compiler/rustc_codegen_llvm/src/type_.rs b/compiler/rustc_codegen_llvm/src/type_.rs
index 89365503138..9ecaf5f24fe 100644
--- a/compiler/rustc_codegen_llvm/src/type_.rs
+++ b/compiler/rustc_codegen_llvm/src/type_.rs
@@ -15,7 +15,7 @@ use rustc_target::callconv::{CastTarget, FnAbi};
 use crate::abi::{FnAbiLlvmExt, LlvmType};
 use crate::context::{CodegenCx, GenericCx, SCx};
 pub(crate) use crate::llvm::Type;
-use crate::llvm::{Bool, False, Metadata, True};
+use crate::llvm::{FALSE, Metadata, TRUE, ToLlvmBool};
 use crate::type_of::LayoutLlvmExt;
 use crate::value::Value;
 use crate::{common, llvm};
@@ -53,7 +53,9 @@ impl<'ll, CX: Borrow<SCx<'ll>>> GenericCx<'ll, CX> {
     }
 
     pub(crate) fn set_struct_body(&self, ty: &'ll Type, els: &[&'ll Type], packed: bool) {
-        unsafe { llvm::LLVMStructSetBody(ty, els.as_ptr(), els.len() as c_uint, packed as Bool) }
+        unsafe {
+            llvm::LLVMStructSetBody(ty, els.as_ptr(), els.len() as c_uint, packed.to_llvm_bool())
+        }
     }
     pub(crate) fn type_void(&self) -> &'ll Type {
         unsafe { llvm::LLVMVoidTypeInContext(self.llcx()) }
@@ -139,7 +141,7 @@ impl<'ll, CX: Borrow<SCx<'ll>>> GenericCx<'ll, CX> {
     }
 
     pub(crate) fn type_variadic_func(&self, args: &[&'ll Type], ret: &'ll Type) -> &'ll Type {
-        unsafe { llvm::LLVMFunctionType(ret, args.as_ptr(), args.len() as c_uint, True) }
+        unsafe { llvm::LLVMFunctionType(ret, args.as_ptr(), args.len() as c_uint, TRUE) }
     }
 
     pub(crate) fn type_i1(&self) -> &'ll Type {
@@ -152,7 +154,7 @@ impl<'ll, CX: Borrow<SCx<'ll>>> GenericCx<'ll, CX> {
                 self.llcx(),
                 els.as_ptr(),
                 els.len() as c_uint,
-                packed as Bool,
+                packed.to_llvm_bool(),
             )
         }
     }
@@ -200,11 +202,11 @@ impl<'ll, CX: Borrow<SCx<'ll>>> BaseTypeCodegenMethods for GenericCx<'ll, CX> {
     }
 
     fn type_func(&self, args: &[&'ll Type], ret: &'ll Type) -> &'ll Type {
-        unsafe { llvm::LLVMFunctionType(ret, args.as_ptr(), args.len() as c_uint, False) }
+        unsafe { llvm::LLVMFunctionType(ret, args.as_ptr(), args.len() as c_uint, FALSE) }
     }
 
     fn type_kind(&self, ty: &'ll Type) -> TypeKind {
-        unsafe { llvm::LLVMRustGetTypeKind(ty).to_generic() }
+        llvm::LLVMGetTypeKind(ty).to_rust().to_generic()
     }
 
     fn type_ptr(&self) -> &'ll Type {
diff --git a/compiler/rustc_codegen_ssa/Cargo.toml b/compiler/rustc_codegen_ssa/Cargo.toml
index 30956fd1855..6b989a96488 100644
--- a/compiler/rustc_codegen_ssa/Cargo.toml
+++ b/compiler/rustc_codegen_ssa/Cargo.toml
@@ -6,12 +6,12 @@ edition = "2024"
 [dependencies]
 # tidy-alphabetical-start
 ar_archive_writer = "0.4.2"
-bitflags = "2.4.1"
+bitflags.workspace = true
 bstr = "1.11.3"
 # `cc` updates often break things, so we pin it here. Cargo enforces "max 1 semver-compat version
 # per crate", so if you change this, you need to also change it in `rustc_llvm`.
 cc = "=1.2.16"
-itertools = "0.12"
+itertools.workspace = true
 pathdiff = "0.2.0"
 regex = "1.4"
 rustc_abi = { path = "../rustc_abi" }
@@ -26,6 +26,7 @@ rustc_hashes = { path = "../rustc_hashes" }
 rustc_hir = { path = "../rustc_hir" }
 rustc_incremental = { path = "../rustc_incremental" }
 rustc_index = { path = "../rustc_index" }
+rustc_lint_defs = { path = "../rustc_lint_defs" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_metadata = { path = "../rustc_metadata" }
 rustc_middle = { path = "../rustc_middle" }
@@ -39,9 +40,9 @@ rustc_trait_selection = { path = "../rustc_trait_selection" }
 serde_json = "1.0.59"
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
 tempfile = "3.2"
-thin-vec = "0.2.12"
+thin-vec.workspace = true
 thorin-dwp = "0.9"
-tracing = "0.1"
+tracing.workspace = true
 wasm-encoder = "0.219"
 # tidy-alphabetical-end
 
diff --git a/compiler/rustc_codegen_ssa/messages.ftl b/compiler/rustc_codegen_ssa/messages.ftl
index b6cfea88363..44b9941691a 100644
--- a/compiler/rustc_codegen_ssa/messages.ftl
+++ b/compiler/rustc_codegen_ssa/messages.ftl
@@ -171,9 +171,6 @@ codegen_ssa_invalid_monomorphization_unsupported_symbol = invalid monomorphizati
 
 codegen_ssa_invalid_monomorphization_unsupported_symbol_of_size = invalid monomorphization of `{$name}` intrinsic: unsupported {$symbol} from `{$in_ty}` with element `{$in_elem}` of size `{$size}` to `{$ret_ty}`
 
-codegen_ssa_invalid_no_sanitize = invalid argument for `no_sanitize`
-    .note = expected one of: `address`, `cfi`, `hwaddress`, `kcfi`, `memory`, `memtag`, `shadow-call-stack`, or `thread`
-
 codegen_ssa_invalid_windows_subsystem = invalid windows subsystem `{$subsystem}`, only `windows` and `console` are allowed
 
 codegen_ssa_ld64_unimplemented_modifier = `as-needed` modifier not implemented yet for ld64
diff --git a/compiler/rustc_codegen_ssa/src/back/apple.rs b/compiler/rustc_codegen_ssa/src/back/apple.rs
index 2274450e20e..b1d646d9265 100644
--- a/compiler/rustc_codegen_ssa/src/back/apple.rs
+++ b/compiler/rustc_codegen_ssa/src/back/apple.rs
@@ -164,7 +164,7 @@ pub(super) fn get_sdk_root(sess: &Session) -> Option<PathBuf> {
     //
     // Note that when cross-compiling from e.g. Linux, the `xcrun` binary may sometimes be provided
     // as a shim by a cross-compilation helper tool. It usually isn't, but we still try nonetheless.
-    match xcrun_show_sdk_path(sdk_name, sess.verbose_internals()) {
+    match xcrun_show_sdk_path(sdk_name, false) {
         Ok((path, stderr)) => {
             // Emit extra stderr, such as if `-verbose` was passed, or if `xcrun` emitted a warning.
             if !stderr.is_empty() {
diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index 4ebe59dc2a7..19c919c0e4e 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -14,11 +14,13 @@ use itertools::Itertools;
 use regex::Regex;
 use rustc_arena::TypedArena;
 use rustc_ast::CRATE_NODE_ID;
+use rustc_attr_parsing::{ShouldEmit, eval_config_entry};
 use rustc_data_structures::fx::FxIndexSet;
 use rustc_data_structures::memmap::Mmap;
 use rustc_data_structures::temp_dir::MaybeTempDir;
 use rustc_errors::{DiagCtxtHandle, LintDiagnostic};
 use rustc_fs_util::{TempDirBuilder, fix_windows_verbatim_for_gcc, try_canonicalize};
+use rustc_hir::attrs::NativeLibKind;
 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
 use rustc_macros::LintDiagnostic;
 use rustc_metadata::fs::{METADATA_FILENAME, copy_to_stdout, emit_wrapper_file};
@@ -38,7 +40,6 @@ use rustc_session::config::{
 use rustc_session::lint::builtin::LINKER_MESSAGES;
 use rustc_session::output::{check_file_is_writeable, invalid_output_for_target, out_filename};
 use rustc_session::search_paths::PathKind;
-use rustc_session::utils::NativeLibKind;
 /// For all the linkers we support, and information they might
 /// need out of the shared crate context before we get rid of it.
 use rustc_session::{Session, filesearch};
@@ -2435,6 +2436,13 @@ fn linker_with_args(
     // Passed after compiler-generated options to support manual overriding when necessary.
     add_user_defined_link_args(cmd, sess);
 
+    // ------------ Builtin configurable linker scripts ------------
+    // The user's link args should be able to overwrite symbols in the compiler's
+    // linker script that were weakly defined (i.e. defined with `PROVIDE()`). For this
+    // to work correctly, the user needs to be able to specify linker arguments like
+    // `--defsym` and `--script` *before* any builtin linker scripts are evaluated.
+    add_link_script(cmd, sess, tmpdir, crate_type);
+
     // ------------ Object code and libraries, order-dependent ------------
 
     // Post-link CRT objects.
@@ -2469,8 +2477,6 @@ fn add_order_independent_options(
 
     let apple_sdk_root = add_apple_sdk(cmd, sess, flavor);
 
-    add_link_script(cmd, sess, tmpdir, crate_type);
-
     if sess.target.os == "fuchsia"
         && crate_type == CrateType::Executable
         && !matches!(flavor, LinkerFlavor::Gnu(Cc::Yes, _))
@@ -3014,7 +3020,9 @@ fn add_dynamic_crate(cmd: &mut dyn Linker, sess: &Session, cratepath: &Path) {
 
 fn relevant_lib(sess: &Session, lib: &NativeLib) -> bool {
     match lib.cfg {
-        Some(ref cfg) => rustc_attr_parsing::cfg_matches(cfg, sess, CRATE_NODE_ID, None),
+        Some(ref cfg) => {
+            eval_config_entry(sess, cfg, CRATE_NODE_ID, None, ShouldEmit::ErrorsAndLints).as_bool()
+        }
         None => true,
     }
 }
diff --git a/compiler/rustc_codegen_ssa/src/back/link/raw_dylib.rs b/compiler/rustc_codegen_ssa/src/back/link/raw_dylib.rs
index b9e0c957363..9f42991d4c0 100644
--- a/compiler/rustc_codegen_ssa/src/back/link/raw_dylib.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link/raw_dylib.rs
@@ -7,9 +7,9 @@ use rustc_data_structures::base_n::{CASE_INSENSITIVE, ToBaseN};
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
 use rustc_data_structures::stable_hasher::StableHasher;
 use rustc_hashes::Hash128;
+use rustc_hir::attrs::NativeLibKind;
 use rustc_session::Session;
 use rustc_session::cstore::DllImport;
-use rustc_session::utils::NativeLibKind;
 use rustc_span::Symbol;
 
 use crate::back::archive::ImportLibraryItem;
@@ -307,11 +307,14 @@ fn create_elf_raw_dylib_stub(sess: &Session, soname: &str, symbols: &[DllImport]
     stub.reserve_section_headers();
     stub.reserve_dynsym();
     stub.reserve_dynstr();
+    let verdef_count = 1 + vers.len();
+    let mut dynamic_entries = 2; // DT_SONAME, DT_NULL
     if !vers.is_empty() {
         stub.reserve_gnu_versym();
-        stub.reserve_gnu_verdef(1 + vers.len(), 1 + vers.len());
+        stub.reserve_gnu_verdef(verdef_count, verdef_count);
+        dynamic_entries += 1; // DT_VERDEFNUM
     }
-    stub.reserve_dynamic(2); // DT_SONAME, DT_NULL
+    stub.reserve_dynamic(dynamic_entries);
 
     // First write the ELF header with the arch information.
     let e_machine = match (arch, sub_arch) {
@@ -443,9 +446,13 @@ fn create_elf_raw_dylib_stub(sess: &Session, soname: &str, symbols: &[DllImport]
     // .dynamic
     // the DT_SONAME will be used by the linker to populate DT_NEEDED
     // which the loader uses to find the library.
-    // DT_NULL terminates the .dynamic table.
     stub.write_align_dynamic();
     stub.write_dynamic_string(elf::DT_SONAME, soname);
+    // LSB section "2.7. Symbol Versioning" requires `DT_VERDEFNUM` to be reliable.
+    if verdef_count > 1 {
+        stub.write_dynamic(elf::DT_VERDEFNUM, verdef_count as u64);
+    }
+    // DT_NULL terminates the .dynamic table.
     stub.write_dynamic(elf::DT_NULL, 0);
 
     stub_buf
diff --git a/compiler/rustc_codegen_ssa/src/back/metadata.rs b/compiler/rustc_codegen_ssa/src/back/metadata.rs
index bf38c02e908..10aaadd5688 100644
--- a/compiler/rustc_codegen_ssa/src/back/metadata.rs
+++ b/compiler/rustc_codegen_ssa/src/back/metadata.rs
@@ -329,12 +329,18 @@ pub(super) fn elf_e_flags(architecture: Architecture, sess: &Session) -> u32 {
             // Source: https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/079772828bd10933d34121117a222b4cc0ee2200/riscv-elf.adoc
             let mut e_flags: u32 = 0x0;
 
-            // Check if compressed is enabled
-            // `unstable_target_features` is used here because "c" is gated behind riscv_target_feature.
-            if sess.unstable_target_features.contains(&sym::c) {
+            // Check if compression is enabled
+            // `unstable_target_features` is used here because "zca" is gated behind riscv_target_feature.
+            if sess.unstable_target_features.contains(&sym::zca) {
                 e_flags |= elf::EF_RISCV_RVC;
             }
 
+            // Check if RVTSO is enabled
+            // `unstable_target_features` is used here because "ztso" is gated behind riscv_target_feature.
+            if sess.unstable_target_features.contains(&sym::ztso) {
+                e_flags |= elf::EF_RISCV_TSO;
+            }
+
             // Set the appropriate flag based on ABI
             // This needs to match LLVM `RISCVELFStreamer.cpp`
             match &*sess.target.llvm_abiname {
diff --git a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
index 7e124f65324..13419bcb22c 100644
--- a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
+++ b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
@@ -306,7 +306,8 @@ fn exported_generic_symbols_provider_local<'tcx>(
     let mut symbols: Vec<_> = vec![];
 
     if tcx.local_crate_exports_generics() {
-        use rustc_middle::mir::mono::{Linkage, MonoItem, Visibility};
+        use rustc_hir::attrs::Linkage;
+        use rustc_middle::mir::mono::{MonoItem, Visibility};
         use rustc_middle::ty::InstanceKind;
 
         // Normally, we require that shared monomorphizations are not hidden,
diff --git a/compiler/rustc_codegen_ssa/src/back/write.rs b/compiler/rustc_codegen_ssa/src/back/write.rs
index f460c900c08..92582dcc399 100644
--- a/compiler/rustc_codegen_ssa/src/back/write.rs
+++ b/compiler/rustc_codegen_ssa/src/back/write.rs
@@ -1,5 +1,6 @@
 use std::assert_matches::assert_matches;
 use std::marker::PhantomData;
+use std::panic::AssertUnwindSafe;
 use std::path::{Path, PathBuf};
 use std::sync::Arc;
 use std::sync::mpsc::{Receiver, Sender, channel};
@@ -7,7 +8,6 @@ use std::{fs, io, mem, str, thread};
 
 use rustc_abi::Size;
 use rustc_ast::attr;
-use rustc_ast::expand::autodiff_attrs::AutoDiffItem;
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::jobserver::{self, Acquired};
 use rustc_data_structures::memmap::Mmap;
@@ -15,7 +15,7 @@ use rustc_data_structures::profiling::{SelfProfilerRef, VerboseTimingGuard};
 use rustc_errors::emitter::Emitter;
 use rustc_errors::translation::Translator;
 use rustc_errors::{
-    Diag, DiagArgMap, DiagCtxt, DiagMessage, ErrCode, FatalError, Level, MultiSpan, Style,
+    Diag, DiagArgMap, DiagCtxt, DiagMessage, ErrCode, FatalErrorMarker, Level, MultiSpan, Style,
     Suggestions,
 };
 use rustc_fs_util::link_or_copy;
@@ -38,7 +38,7 @@ use tracing::debug;
 use super::link::{self, ensure_removed};
 use super::lto::{self, SerializedModule};
 use crate::back::lto::check_lto_allowed;
-use crate::errors::{AutodiffWithoutLto, ErrorCreatingRemarkDir};
+use crate::errors::ErrorCreatingRemarkDir;
 use crate::traits::*;
 use crate::{
     CachedModuleCodegen, CodegenResults, CompiledModule, CrateInfo, ModuleCodegen, ModuleKind,
@@ -76,12 +76,9 @@ pub struct ModuleConfig {
     /// Names of additional optimization passes to run.
     pub passes: Vec<String>,
     /// Some(level) to optimize at a certain level, or None to run
-    /// absolutely no optimizations (used for the metadata module).
+    /// absolutely no optimizations (used for the allocator module).
     pub opt_level: Option<config::OptLevel>,
 
-    /// Some(level) to optimize binary size, or None to not affect program size.
-    pub opt_size: Option<config::OptLevel>,
-
     pub pgo_gen: SwitchWithOptPath,
     pub pgo_use: Option<PathBuf>,
     pub pgo_sample_use: Option<PathBuf>,
@@ -102,7 +99,6 @@ pub struct ModuleConfig {
     pub emit_obj: EmitObj,
     pub emit_thin_lto: bool,
     pub emit_thin_lto_summary: bool,
-    pub bc_cmdline: String,
 
     // Miscellaneous flags. These are mostly copied from command-line
     // options.
@@ -110,7 +106,6 @@ pub struct ModuleConfig {
     pub lint_llvm_ir: bool,
     pub no_prepopulate_passes: bool,
     pub no_builtins: bool,
-    pub time_module: bool,
     pub vectorize_loop: bool,
     pub vectorize_slp: bool,
     pub merge_functions: bool,
@@ -160,7 +155,6 @@ impl ModuleConfig {
             passes: if_regular!(sess.opts.cg.passes.clone(), vec![]),
 
             opt_level: opt_level_and_size,
-            opt_size: opt_level_and_size,
 
             pgo_gen: if_regular!(
                 sess.opts.cg.profile_generate.clone(),
@@ -210,17 +204,12 @@ impl ModuleConfig {
                 sess.opts.output_types.contains_key(&OutputType::ThinLinkBitcode),
                 false
             ),
-            bc_cmdline: sess.target.bitcode_llvm_cmdline.to_string(),
 
             verify_llvm_ir: sess.verify_llvm_ir(),
             lint_llvm_ir: sess.opts.unstable_opts.lint_llvm_ir,
             no_prepopulate_passes: sess.opts.cg.no_prepopulate_passes,
             no_builtins: no_builtins || sess.target.no_builtins,
 
-            // Exclude metadata and allocator modules from time_passes output,
-            // since they throw off the "LLVM passes" measurement.
-            time_module: if_regular!(true, false),
-
             // Copy what clang does by turning on loop vectorization at O2 and
             // slp vectorization at O3.
             vectorize_loop: !sess.opts.cg.no_vectorize_loops
@@ -396,8 +385,7 @@ fn generate_thin_lto_work<B: ExtraBackendMethods>(
         each_linked_rlib_for_lto,
         needs_thin_lto,
         import_only_modules,
-    )
-    .unwrap_or_else(|e| e.raise());
+    );
     lto_modules
         .into_iter()
         .map(|module| {
@@ -443,7 +431,6 @@ pub(crate) fn start_async_codegen<B: ExtraBackendMethods>(
     backend: B,
     tcx: TyCtxt<'_>,
     target_cpu: String,
-    autodiff_items: &[AutoDiffItem],
 ) -> OngoingCodegen<B> {
     let (coordinator_send, coordinator_receive) = channel();
 
@@ -462,7 +449,6 @@ pub(crate) fn start_async_codegen<B: ExtraBackendMethods>(
         backend.clone(),
         tcx,
         &crate_info,
-        autodiff_items,
         shared_emitter,
         codegen_worker_send,
         coordinator_receive,
@@ -717,7 +703,6 @@ pub(crate) enum WorkItem<B: WriteBackendMethods> {
         each_linked_rlib_for_lto: Vec<PathBuf>,
         needs_fat_lto: Vec<FatLtoInput<B>>,
         import_only_modules: Vec<(SerializedModule<B::ModuleBuffer>, WorkProduct)>,
-        autodiff: Vec<AutoDiffItem>,
     },
     /// Performs thin-LTO on the given module.
     ThinLto(lto::ThinModule<B>),
@@ -848,11 +833,11 @@ fn execute_optimize_work_item<B: ExtraBackendMethods>(
     cgcx: &CodegenContext<B>,
     mut module: ModuleCodegen<B::Module>,
     module_config: &ModuleConfig,
-) -> Result<WorkItemResult<B>, FatalError> {
+) -> WorkItemResult<B> {
     let dcx = cgcx.create_dcx();
     let dcx = dcx.handle();
 
-    B::optimize(cgcx, dcx, &mut module, module_config)?;
+    B::optimize(cgcx, dcx, &mut module, module_config);
 
     // After we've done the initial round of optimizations we need to
     // decide whether to synchronously codegen this module or ship it
@@ -872,8 +857,8 @@ fn execute_optimize_work_item<B: ExtraBackendMethods>(
 
     match lto_type {
         ComputedLtoType::No => {
-            let module = B::codegen(cgcx, module, module_config)?;
-            Ok(WorkItemResult::Finished(module))
+            let module = B::codegen(cgcx, module, module_config);
+            WorkItemResult::Finished(module)
         }
         ComputedLtoType::Thin => {
             let (name, thin_buffer) = B::prepare_thin(module, false);
@@ -882,7 +867,7 @@ fn execute_optimize_work_item<B: ExtraBackendMethods>(
                     panic!("Error writing pre-lto-bitcode file `{}`: {}", path.display(), e);
                 });
             }
-            Ok(WorkItemResult::NeedsThinLto(name, thin_buffer))
+            WorkItemResult::NeedsThinLto(name, thin_buffer)
         }
         ComputedLtoType::Fat => match bitcode {
             Some(path) => {
@@ -890,12 +875,12 @@ fn execute_optimize_work_item<B: ExtraBackendMethods>(
                 fs::write(&path, buffer.data()).unwrap_or_else(|e| {
                     panic!("Error writing pre-lto-bitcode file `{}`: {}", path.display(), e);
                 });
-                Ok(WorkItemResult::NeedsFatLto(FatLtoInput::Serialized {
+                WorkItemResult::NeedsFatLto(FatLtoInput::Serialized {
                     name,
                     buffer: SerializedModule::Local(buffer),
-                }))
+                })
             }
-            None => Ok(WorkItemResult::NeedsFatLto(FatLtoInput::InMemory(module))),
+            None => WorkItemResult::NeedsFatLto(FatLtoInput::InMemory(module)),
         },
     }
 }
@@ -990,9 +975,8 @@ fn execute_fat_lto_work_item<B: ExtraBackendMethods>(
     each_linked_rlib_for_lto: &[PathBuf],
     mut needs_fat_lto: Vec<FatLtoInput<B>>,
     import_only_modules: Vec<(SerializedModule<B::ModuleBuffer>, WorkProduct)>,
-    autodiff: Vec<AutoDiffItem>,
     module_config: &ModuleConfig,
-) -> Result<WorkItemResult<B>, FatalError> {
+) -> WorkItemResult<B> {
     for (module, wp) in import_only_modules {
         needs_fat_lto.push(FatLtoInput::Serialized { name: wp.cgu_name, buffer: module })
     }
@@ -1002,20 +986,19 @@ fn execute_fat_lto_work_item<B: ExtraBackendMethods>(
         exported_symbols_for_lto,
         each_linked_rlib_for_lto,
         needs_fat_lto,
-        autodiff,
-    )?;
-    let module = B::codegen(cgcx, module, module_config)?;
-    Ok(WorkItemResult::Finished(module))
+    );
+    let module = B::codegen(cgcx, module, module_config);
+    WorkItemResult::Finished(module)
 }
 
 fn execute_thin_lto_work_item<B: ExtraBackendMethods>(
     cgcx: &CodegenContext<B>,
     module: lto::ThinModule<B>,
     module_config: &ModuleConfig,
-) -> Result<WorkItemResult<B>, FatalError> {
-    let module = B::optimize_thin(cgcx, module)?;
-    let module = B::codegen(cgcx, module, module_config)?;
-    Ok(WorkItemResult::Finished(module))
+) -> WorkItemResult<B> {
+    let module = B::optimize_thin(cgcx, module);
+    let module = B::codegen(cgcx, module, module_config);
+    WorkItemResult::Finished(module)
 }
 
 /// Messages sent to the coordinator.
@@ -1094,7 +1077,6 @@ fn start_executing_work<B: ExtraBackendMethods>(
     backend: B,
     tcx: TyCtxt<'_>,
     crate_info: &CrateInfo,
-    autodiff_items: &[AutoDiffItem],
     shared_emitter: SharedEmitter,
     codegen_worker_send: Sender<CguMessage>,
     coordinator_receive: Receiver<Message<B>>,
@@ -1104,7 +1086,6 @@ fn start_executing_work<B: ExtraBackendMethods>(
 ) -> thread::JoinHandle<Result<CompiledModules, ()>> {
     let coordinator_send = tx_to_llvm_workers;
     let sess = tcx.sess;
-    let autodiff_items = autodiff_items.to_vec();
 
     let mut each_linked_rlib_for_lto = Vec::new();
     let mut each_linked_rlib_file_for_lto = Vec::new();
@@ -1437,7 +1418,6 @@ fn start_executing_work<B: ExtraBackendMethods>(
                                 each_linked_rlib_for_lto: each_linked_rlib_file_for_lto,
                                 needs_fat_lto,
                                 import_only_modules,
-                                autodiff: autodiff_items.clone(),
                             },
                             0,
                         ));
@@ -1445,11 +1425,6 @@ fn start_executing_work<B: ExtraBackendMethods>(
                             helper.request_token();
                         }
                     } else {
-                        if !autodiff_items.is_empty() {
-                            let dcx = cgcx.create_dcx();
-                            dcx.handle().emit_fatal(AutodiffWithoutLto {});
-                        }
-
                         for (work, cost) in generate_thin_lto_work(
                             &cgcx,
                             &exported_symbols_for_lto,
@@ -1729,44 +1704,17 @@ fn spawn_work<'a, B: ExtraBackendMethods>(
     llvm_start_time: &mut Option<VerboseTimingGuard<'a>>,
     work: WorkItem<B>,
 ) {
-    if cgcx.config(work.module_kind()).time_module && llvm_start_time.is_none() {
+    if llvm_start_time.is_none() {
         *llvm_start_time = Some(cgcx.prof.verbose_generic_activity("LLVM_passes"));
     }
 
     let cgcx = cgcx.clone();
 
     B::spawn_named_thread(cgcx.time_trace, work.short_description(), move || {
-        // Set up a destructor which will fire off a message that we're done as
-        // we exit.
-        struct Bomb<B: ExtraBackendMethods> {
-            coordinator_send: Sender<Message<B>>,
-            result: Option<Result<WorkItemResult<B>, FatalError>>,
-        }
-        impl<B: ExtraBackendMethods> Drop for Bomb<B> {
-            fn drop(&mut self) {
-                let msg = match self.result.take() {
-                    Some(Ok(result)) => Message::WorkItem::<B> { result: Ok(result) },
-                    Some(Err(FatalError)) => {
-                        Message::WorkItem::<B> { result: Err(Some(WorkerFatalError)) }
-                    }
-                    None => Message::WorkItem::<B> { result: Err(None) },
-                };
-                drop(self.coordinator_send.send(msg));
-            }
-        }
-
-        let mut bomb = Bomb::<B> { coordinator_send, result: None };
-
-        // Execute the work itself, and if it finishes successfully then flag
-        // ourselves as a success as well.
-        //
-        // Note that we ignore any `FatalError` coming out of `execute_work_item`,
-        // as a diagnostic was already sent off to the main thread - just
-        // surface that there was an error in this worker.
-        bomb.result = {
+        let result = std::panic::catch_unwind(AssertUnwindSafe(|| {
             let module_config = cgcx.config(work.module_kind());
 
-            Some(match work {
+            match work {
                 WorkItem::Optimize(m) => {
                     let _timer =
                         cgcx.prof.generic_activity_with_arg("codegen_module_optimize", &*m.name);
@@ -1777,14 +1725,13 @@ fn spawn_work<'a, B: ExtraBackendMethods>(
                         "codegen_copy_artifacts_from_incr_cache",
                         &*m.name,
                     );
-                    Ok(execute_copy_from_cache_work_item(&cgcx, m, module_config))
+                    execute_copy_from_cache_work_item(&cgcx, m, module_config)
                 }
                 WorkItem::FatLto {
                     exported_symbols_for_lto,
                     each_linked_rlib_for_lto,
                     needs_fat_lto,
                     import_only_modules,
-                    autodiff,
                 } => {
                     let _timer = cgcx
                         .prof
@@ -1795,7 +1742,6 @@ fn spawn_work<'a, B: ExtraBackendMethods>(
                         &each_linked_rlib_for_lto,
                         needs_fat_lto,
                         import_only_modules,
-                        autodiff,
                         module_config,
                     )
                 }
@@ -1804,8 +1750,22 @@ fn spawn_work<'a, B: ExtraBackendMethods>(
                         cgcx.prof.generic_activity_with_arg("codegen_module_perform_lto", m.name());
                     execute_thin_lto_work_item(&cgcx, m, module_config)
                 }
-            })
+            }
+        }));
+
+        let msg = match result {
+            Ok(result) => Message::WorkItem::<B> { result: Ok(result) },
+
+            // We ignore any `FatalError` coming out of `execute_work_item`, as a
+            // diagnostic was already sent off to the main thread - just surface
+            // that there was an error in this worker.
+            Err(err) if err.is::<FatalErrorMarker>() => {
+                Message::WorkItem::<B> { result: Err(Some(WorkerFatalError)) }
+            }
+
+            Err(_) => Message::WorkItem::<B> { result: Err(None) },
         };
+        drop(coordinator_send.send(msg));
     })
     .expect("failed to spawn work thread");
 }
@@ -1986,10 +1946,13 @@ impl<B: ExtraBackendMethods> Drop for Coordinator<B> {
 pub struct OngoingCodegen<B: ExtraBackendMethods> {
     pub backend: B,
     pub crate_info: CrateInfo,
-    pub codegen_worker_receive: Receiver<CguMessage>,
-    pub shared_emitter_main: SharedEmitterMain,
     pub output_filenames: Arc<OutputFilenames>,
+    // Field order below is intended to terminate the coordinator thread before two fields below
+    // drop and prematurely close channels used by coordinator thread. See `Coordinator`'s
+    // `Drop` implementation for more info.
     pub coordinator: Coordinator<B>,
+    pub codegen_worker_receive: Receiver<CguMessage>,
+    pub shared_emitter_main: SharedEmitterMain,
 }
 
 impl<B: ExtraBackendMethods> OngoingCodegen<B> {
diff --git a/compiler/rustc_codegen_ssa/src/base.rs b/compiler/rustc_codegen_ssa/src/base.rs
index b4556ced0b3..8abaf201aba 100644
--- a/compiler/rustc_codegen_ssa/src/base.rs
+++ b/compiler/rustc_codegen_ssa/src/base.rs
@@ -647,7 +647,7 @@ pub fn codegen_crate<B: ExtraBackendMethods>(
 ) -> OngoingCodegen<B> {
     // Skip crate items and just output metadata in -Z no-codegen mode.
     if tcx.sess.opts.unstable_opts.no_codegen || !tcx.sess.opts.output_types.should_codegen() {
-        let ongoing_codegen = start_async_codegen(backend, tcx, target_cpu, &[]);
+        let ongoing_codegen = start_async_codegen(backend, tcx, target_cpu);
 
         ongoing_codegen.codegen_finished(tcx);
 
@@ -665,8 +665,7 @@ pub fn codegen_crate<B: ExtraBackendMethods>(
 
     // Run the monomorphization collector and partition the collected items into
     // codegen units.
-    let MonoItemPartitions { codegen_units, autodiff_items, .. } =
-        tcx.collect_and_partition_mono_items(());
+    let MonoItemPartitions { codegen_units, .. } = tcx.collect_and_partition_mono_items(());
 
     // Force all codegen_unit queries so they are already either red or green
     // when compile_codegen_unit accesses them. We are not able to re-execute
@@ -679,34 +678,7 @@ pub fn codegen_crate<B: ExtraBackendMethods>(
         }
     }
 
-    let ongoing_codegen = start_async_codegen(backend.clone(), tcx, target_cpu, autodiff_items);
-
-    // Codegen an allocator shim, if necessary.
-    if let Some(kind) = allocator_kind_for_codegen(tcx) {
-        let llmod_id =
-            cgu_name_builder.build_cgu_name(LOCAL_CRATE, &["crate"], Some("allocator")).to_string();
-        let module_llvm = tcx.sess.time("write_allocator_module", || {
-            backend.codegen_allocator(
-                tcx,
-                &llmod_id,
-                kind,
-                // If allocator_kind is Some then alloc_error_handler_kind must
-                // also be Some.
-                tcx.alloc_error_handler_kind(()).unwrap(),
-            )
-        });
-
-        ongoing_codegen.wait_for_signal_to_codegen_item();
-        ongoing_codegen.check_for_errors(tcx.sess);
-
-        // These modules are generally cheap and won't throw off scheduling.
-        let cost = 0;
-        submit_codegened_module_to_llvm(
-            &ongoing_codegen.coordinator,
-            ModuleCodegen::new_allocator(llmod_id, module_llvm),
-            cost,
-        );
-    }
+    let ongoing_codegen = start_async_codegen(backend.clone(), tcx, target_cpu);
 
     // For better throughput during parallel processing by LLVM, we used to sort
     // CGUs largest to smallest. This would lead to better thread utilization
@@ -823,6 +795,35 @@ pub fn codegen_crate<B: ExtraBackendMethods>(
         }
     }
 
+    // Codegen an allocator shim, if necessary.
+    // Do this last to ensure the LLVM_passes timer doesn't start while no CGUs have been codegened
+    // yet for the backend to optimize.
+    if let Some(kind) = allocator_kind_for_codegen(tcx) {
+        let llmod_id =
+            cgu_name_builder.build_cgu_name(LOCAL_CRATE, &["crate"], Some("allocator")).to_string();
+        let module_llvm = tcx.sess.time("write_allocator_module", || {
+            backend.codegen_allocator(
+                tcx,
+                &llmod_id,
+                kind,
+                // If allocator_kind is Some then alloc_error_handler_kind must
+                // also be Some.
+                tcx.alloc_error_handler_kind(()).unwrap(),
+            )
+        });
+
+        ongoing_codegen.wait_for_signal_to_codegen_item();
+        ongoing_codegen.check_for_errors(tcx.sess);
+
+        // These modules are generally cheap and won't throw off scheduling.
+        let cost = 0;
+        submit_codegened_module_to_llvm(
+            &ongoing_codegen.coordinator,
+            ModuleCodegen::new_allocator(llmod_id, module_llvm),
+            cost,
+        );
+    }
+
     ongoing_codegen.codegen_finished(tcx);
 
     // Since the main thread is sometimes blocked during codegen, we keep track
@@ -857,7 +858,7 @@ pub fn is_call_from_compiler_builtins_to_upstream_monomorphization<'tcx>(
     instance: Instance<'tcx>,
 ) -> bool {
     fn is_llvm_intrinsic(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
-        if let Some(name) = tcx.codegen_fn_attrs(def_id).link_name {
+        if let Some(name) = tcx.codegen_fn_attrs(def_id).symbol_name {
             name.as_str().starts_with("llvm.")
         } else {
             false
diff --git a/compiler/rustc_codegen_ssa/src/codegen_attrs.rs b/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
index 7f54a47327a..961bb788149 100644
--- a/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
+++ b/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
@@ -6,12 +6,10 @@ use rustc_ast::{LitKind, MetaItem, MetaItemInner, attr};
 use rustc_hir::attrs::{AttributeKind, InlineAttr, InstructionSetAttr, UsedBy};
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LOCAL_CRATE, LocalDefId};
-use rustc_hir::weak_lang_items::WEAK_LANG_ITEMS;
 use rustc_hir::{self as hir, Attribute, LangItem, find_attr, lang_items};
 use rustc_middle::middle::codegen_fn_attrs::{
     CodegenFnAttrFlags, CodegenFnAttrs, PatchableFunctionEntry,
 };
-use rustc_middle::mir::mono::Linkage;
 use rustc_middle::query::Providers;
 use rustc_middle::span_bug;
 use rustc_middle::ty::{self as ty, TyCtxt};
@@ -26,31 +24,6 @@ use crate::target_features::{
     check_target_feature_trait_unsafe, check_tied_features, from_target_feature_attr,
 };
 
-fn linkage_by_name(tcx: TyCtxt<'_>, def_id: LocalDefId, name: &str) -> Linkage {
-    use rustc_middle::mir::mono::Linkage::*;
-
-    // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
-    // applicable to variable declarations and may not really make sense for
-    // Rust code in the first place but allow them anyway and trust that the
-    // user knows what they're doing. Who knows, unanticipated use cases may pop
-    // up in the future.
-    //
-    // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
-    // and don't have to be, LLVM treats them as no-ops.
-    match name {
-        "available_externally" => AvailableExternally,
-        "common" => Common,
-        "extern_weak" => ExternalWeak,
-        "external" => External,
-        "internal" => Internal,
-        "linkonce" => LinkOnceAny,
-        "linkonce_odr" => LinkOnceODR,
-        "weak" => WeakAny,
-        "weak_odr" => WeakODR,
-        _ => tcx.dcx().span_fatal(tcx.def_span(def_id), "invalid linkage specified"),
-    }
-}
-
 /// In some cases, attributes are only valid on functions, but it's the `check_attr`
 /// pass that checks that they aren't used anywhere else, rather than this module.
 /// In these cases, we bail from performing further checks that are only meaningful for
@@ -103,39 +76,6 @@ fn parse_instruction_set_attr(tcx: TyCtxt<'_>, attr: &Attribute) -> Option<Instr
     }
 }
 
-// FIXME(jdonszelmann): remove when linkage becomes a parsed attr
-fn parse_linkage_attr(tcx: TyCtxt<'_>, did: LocalDefId, attr: &Attribute) -> Option<Linkage> {
-    let val = attr.value_str()?;
-    let linkage = linkage_by_name(tcx, did, val.as_str());
-    Some(linkage)
-}
-
-// FIXME(jdonszelmann): remove when no_sanitize becomes a parsed attr
-fn parse_no_sanitize_attr(tcx: TyCtxt<'_>, attr: &Attribute) -> Option<SanitizerSet> {
-    let list = attr.meta_item_list()?;
-    let mut sanitizer_set = SanitizerSet::empty();
-
-    for item in list.iter() {
-        match item.name() {
-            Some(sym::address) => {
-                sanitizer_set |= SanitizerSet::ADDRESS | SanitizerSet::KERNELADDRESS
-            }
-            Some(sym::cfi) => sanitizer_set |= SanitizerSet::CFI,
-            Some(sym::kcfi) => sanitizer_set |= SanitizerSet::KCFI,
-            Some(sym::memory) => sanitizer_set |= SanitizerSet::MEMORY,
-            Some(sym::memtag) => sanitizer_set |= SanitizerSet::MEMTAG,
-            Some(sym::shadow_call_stack) => sanitizer_set |= SanitizerSet::SHADOWCALLSTACK,
-            Some(sym::thread) => sanitizer_set |= SanitizerSet::THREAD,
-            Some(sym::hwaddress) => sanitizer_set |= SanitizerSet::HWADDRESS,
-            _ => {
-                tcx.dcx().emit_err(errors::InvalidNoSanitize { span: item.span() });
-            }
-        }
-    }
-
-    Some(sanitizer_set)
-}
-
 // FIXME(jdonszelmann): remove when patchable_function_entry becomes a parsed attr
 fn parse_patchable_function_entry(
     tcx: TyCtxt<'_>,
@@ -194,7 +134,7 @@ fn parse_patchable_function_entry(
 #[derive(Default)]
 struct InterestingAttributeDiagnosticSpans {
     link_ordinal: Option<Span>,
-    no_sanitize: Option<Span>,
+    sanitize: Option<Span>,
     inline: Option<Span>,
     no_mangle: Option<Span>,
 }
@@ -210,20 +150,12 @@ fn process_builtin_attrs(
     let mut interesting_spans = InterestingAttributeDiagnosticSpans::default();
     let rust_target_features = tcx.rust_target_features(LOCAL_CRATE);
 
-    // If our rustc version supports autodiff/enzyme, then we call our handler
-    // to check for any `#[rustc_autodiff(...)]` attributes.
-    // FIXME(jdonszelmann): merge with loop below
-    if cfg!(llvm_enzyme) {
-        let ad = autodiff_attrs(tcx, did.into());
-        codegen_fn_attrs.autodiff_item = ad;
-    }
-
     for attr in attrs.iter() {
         if let hir::Attribute::Parsed(p) = attr {
             match p {
                 AttributeKind::Cold(_) => codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD,
                 AttributeKind::ExportName { name, .. } => {
-                    codegen_fn_attrs.export_name = Some(*name)
+                    codegen_fn_attrs.symbol_name = Some(*name)
                 }
                 AttributeKind::Inline(inline, span) => {
                     codegen_fn_attrs.inline = *inline;
@@ -231,7 +163,13 @@ fn process_builtin_attrs(
                 }
                 AttributeKind::Naked(_) => codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED,
                 AttributeKind::Align { align, .. } => codegen_fn_attrs.alignment = Some(*align),
-                AttributeKind::LinkName { name, .. } => codegen_fn_attrs.link_name = Some(*name),
+                AttributeKind::LinkName { name, .. } => {
+                    // FIXME Remove check for foreign functions once #[link_name] on non-foreign
+                    // functions is a hard error
+                    if tcx.is_foreign_item(did) {
+                        codegen_fn_attrs.symbol_name = Some(*name);
+                    }
+                }
                 AttributeKind::LinkOrdinal { ordinal, span } => {
                     codegen_fn_attrs.link_ordinal = Some(*ordinal);
                     interesting_spans.link_ordinal = Some(*span);
@@ -255,7 +193,7 @@ fn process_builtin_attrs(
                     }
                 }
                 AttributeKind::Optimize(optimize, _) => codegen_fn_attrs.optimize = *optimize,
-                AttributeKind::TargetFeature(features, attr_span) => {
+                AttributeKind::TargetFeature { features, attr_span, was_forced } => {
                     let Some(sig) = tcx.hir_node_by_def_id(did).fn_sig() else {
                         tcx.dcx().span_delayed_bug(*attr_span, "target_feature applied to non-fn");
                         continue;
@@ -263,7 +201,7 @@ fn process_builtin_attrs(
                     let safe_target_features =
                         matches!(sig.header.safety, hir::HeaderSafety::SafeTargetFeatures);
                     codegen_fn_attrs.safe_target_features = safe_target_features;
-                    if safe_target_features {
+                    if safe_target_features && !was_forced {
                         if tcx.sess.target.is_like_wasm || tcx.sess.opts.actually_rustdoc {
                             // The `#[target_feature]` attribute is allowed on
                             // WebAssembly targets on all functions. Prior to stabilizing
@@ -294,6 +232,7 @@ fn process_builtin_attrs(
                         tcx,
                         did,
                         features,
+                        *was_forced,
                         rust_target_features,
                         &mut codegen_fn_attrs.target_features,
                     );
@@ -332,6 +271,31 @@ fn process_builtin_attrs(
                 AttributeKind::StdInternalSymbol(_) => {
                     codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL
                 }
+                AttributeKind::Linkage(linkage, _) => {
+                    let linkage = Some(*linkage);
+
+                    if tcx.is_foreign_item(did) {
+                        codegen_fn_attrs.import_linkage = linkage;
+
+                        if tcx.is_mutable_static(did.into()) {
+                            let mut diag = tcx.dcx().struct_span_err(
+                                attr.span(),
+                                "extern mutable statics are not allowed with `#[linkage]`",
+                            );
+                            diag.note(
+                                "marking the extern static mutable would allow changing which \
+                                symbol the static references rather than make the target of the \
+                                symbol mutable",
+                            );
+                            diag.emit();
+                        }
+                    } else {
+                        codegen_fn_attrs.linkage = linkage;
+                    }
+                }
+                AttributeKind::Sanitize { span, .. } => {
+                    interesting_spans.sanitize = Some(*span);
+                }
                 _ => {}
             }
         }
@@ -349,33 +313,6 @@ fn process_builtin_attrs(
                 codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR_ZEROED
             }
             sym::thread_local => codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL,
-            sym::linkage => {
-                let linkage = parse_linkage_attr(tcx, did, attr);
-
-                if tcx.is_foreign_item(did) {
-                    codegen_fn_attrs.import_linkage = linkage;
-
-                    if tcx.is_mutable_static(did.into()) {
-                        let mut diag = tcx.dcx().struct_span_err(
-                            attr.span(),
-                            "extern mutable statics are not allowed with `#[linkage]`",
-                        );
-                        diag.note(
-                            "marking the extern static mutable would allow changing which \
-                            symbol the static references rather than make the target of the \
-                            symbol mutable",
-                        );
-                        diag.emit();
-                    }
-                } else {
-                    codegen_fn_attrs.linkage = linkage;
-                }
-            }
-            sym::no_sanitize => {
-                interesting_spans.no_sanitize = Some(attr.span());
-                codegen_fn_attrs.no_sanitize |=
-                    parse_no_sanitize_attr(tcx, attr).unwrap_or_default();
-            }
             sym::instruction_set => {
                 codegen_fn_attrs.instruction_set = parse_instruction_set_attr(tcx, attr)
             }
@@ -399,6 +336,8 @@ fn apply_overrides(tcx: TyCtxt<'_>, did: LocalDefId, codegen_fn_attrs: &mut Code
     codegen_fn_attrs.alignment =
         Ord::max(codegen_fn_attrs.alignment, tcx.sess.opts.unstable_opts.min_function_alignment);
 
+    // Compute the disabled sanitizers.
+    codegen_fn_attrs.no_sanitize |= tcx.disabled_sanitizers_for(did);
     // On trait methods, inherit the `#[align]` of the trait's method prototype.
     codegen_fn_attrs.alignment = Ord::max(codegen_fn_attrs.alignment, tcx.inherited_align(did));
 
@@ -443,6 +382,29 @@ fn apply_overrides(tcx: TyCtxt<'_>, did: LocalDefId, codegen_fn_attrs: &mut Code
     if tcx.should_inherit_track_caller(did) {
         codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
     }
+
+    // Foreign items by default use no mangling for their symbol name.
+    if tcx.is_foreign_item(did) {
+        codegen_fn_attrs.flags |= CodegenFnAttrFlags::FOREIGN_ITEM;
+
+        // There's a few exceptions to this rule though:
+        if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
+            // * `#[rustc_std_internal_symbol]` mangles the symbol name in a special way
+            //   both for exports and imports through foreign items. This is handled further,
+            //   during symbol mangling logic.
+        } else if codegen_fn_attrs.symbol_name.is_some() {
+            // * This can be overridden with the `#[link_name]` attribute
+        } else {
+            // NOTE: there's one more exception that we cannot apply here. On wasm,
+            // some items cannot be `no_mangle`.
+            // However, we don't have enough information here to determine that.
+            // As such, no_mangle foreign items on wasm that have the same defid as some
+            // import will *still* be mangled despite this.
+            //
+            // if none of the exceptions apply; apply no_mangle
+            codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
+        }
+    }
 }
 
 fn check_result(
@@ -475,17 +437,17 @@ fn check_result(
     if !codegen_fn_attrs.no_sanitize.is_empty()
         && codegen_fn_attrs.inline.always()
         && let (Some(no_sanitize_span), Some(inline_span)) =
-            (interesting_spans.no_sanitize, interesting_spans.inline)
+            (interesting_spans.sanitize, interesting_spans.inline)
     {
         let hir_id = tcx.local_def_id_to_hir_id(did);
         tcx.node_span_lint(lint::builtin::INLINE_NO_SANITIZE, hir_id, no_sanitize_span, |lint| {
-            lint.primary_message("`no_sanitize` will have no effect after inlining");
+            lint.primary_message("setting `sanitize` off will have no effect after inlining");
             lint.span_note(inline_span, "inlining requested here");
         })
     }
 
     // error when specifying link_name together with link_ordinal
-    if let Some(_) = codegen_fn_attrs.link_name
+    if let Some(_) = codegen_fn_attrs.symbol_name
         && let Some(_) = codegen_fn_attrs.link_ordinal
     {
         let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
@@ -505,7 +467,7 @@ fn check_result(
             .collect(),
     ) {
         let span =
-            find_attr!(tcx.get_all_attrs(did), AttributeKind::TargetFeature(_, span) => *span)
+            find_attr!(tcx.get_all_attrs(did), AttributeKind::TargetFeature{attr_span: span, ..} => *span)
                 .unwrap_or_else(|| tcx.def_span(did));
 
         tcx.dcx()
@@ -532,14 +494,11 @@ fn handle_lang_items(
     // strippable by the linker.
     //
     // Additionally weak lang items have predetermined symbol names.
-    if let Some(lang_item) = lang_item {
-        if WEAK_LANG_ITEMS.contains(&lang_item) {
-            codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
-        }
-        if let Some(link_name) = lang_item.link_name() {
-            codegen_fn_attrs.export_name = Some(link_name);
-            codegen_fn_attrs.link_name = Some(link_name);
-        }
+    if let Some(lang_item) = lang_item
+        && let Some(link_name) = lang_item.link_name()
+    {
+        codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
+        codegen_fn_attrs.symbol_name = Some(link_name);
     }
 
     // error when using no_mangle on a lang item item
@@ -605,6 +564,32 @@ fn opt_trait_item(tcx: TyCtxt<'_>, def_id: DefId) -> Option<DefId> {
     }
 }
 
+fn disabled_sanitizers_for(tcx: TyCtxt<'_>, did: LocalDefId) -> SanitizerSet {
+    // Backtrack to the crate root.
+    let mut disabled = match tcx.opt_local_parent(did) {
+        // Check the parent (recursively).
+        Some(parent) => tcx.disabled_sanitizers_for(parent),
+        // We reached the crate root without seeing an attribute, so
+        // there is no sanitizers to exclude.
+        None => SanitizerSet::empty(),
+    };
+
+    // Check for a sanitize annotation directly on this def.
+    if let Some((on_set, off_set)) = find_attr!(tcx.get_all_attrs(did), AttributeKind::Sanitize {on_set, off_set, ..} => (on_set, off_set))
+    {
+        // the on set is the set of sanitizers explicitly enabled.
+        // we mask those out since we want the set of disabled sanitizers here
+        disabled &= !*on_set;
+        // the off set is the set of sanitizers explicitly disabled.
+        // we or those in here.
+        disabled |= *off_set;
+        // the on set and off set are distjoint since there's a third option: unset.
+        // a node may not set the sanitizer setting in which case it inherits from parents.
+        // the code above in this function does this backtracking
+    }
+    disabled
+}
+
 /// Checks if the provided DefId is a method in a trait impl for a trait which has track_caller
 /// applied to the method prototype.
 fn should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
@@ -624,7 +609,7 @@ fn inherited_align<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> Option<Align> {
 /// placeholder functions. We wrote the rustc_autodiff attributes ourself, so this should never
 /// panic, unless we introduced a bug when parsing the autodiff macro.
 //FIXME(jdonszelmann): put in the main loop. No need to have two..... :/ Let's do that when we make autodiff parsed.
-fn autodiff_attrs(tcx: TyCtxt<'_>, id: DefId) -> Option<AutoDiffAttrs> {
+pub fn autodiff_attrs(tcx: TyCtxt<'_>, id: DefId) -> Option<AutoDiffAttrs> {
     let attrs = tcx.get_attrs(id, sym::rustc_autodiff);
 
     let attrs = attrs.filter(|attr| attr.has_name(sym::rustc_autodiff)).collect::<Vec<_>>();
@@ -729,6 +714,11 @@ fn autodiff_attrs(tcx: TyCtxt<'_>, id: DefId) -> Option<AutoDiffAttrs> {
 }
 
 pub(crate) fn provide(providers: &mut Providers) {
-    *providers =
-        Providers { codegen_fn_attrs, should_inherit_track_caller, inherited_align, ..*providers };
+    *providers = Providers {
+        codegen_fn_attrs,
+        should_inherit_track_caller,
+        inherited_align,
+        disabled_sanitizers_for,
+        ..*providers
+    };
 }
diff --git a/compiler/rustc_codegen_ssa/src/common.rs b/compiler/rustc_codegen_ssa/src/common.rs
index a6fd6c763ed..08e2f355953 100644
--- a/compiler/rustc_codegen_ssa/src/common.rs
+++ b/compiler/rustc_codegen_ssa/src/common.rs
@@ -1,10 +1,11 @@
 #![allow(non_camel_case_types)]
 
 use rustc_hir::LangItem;
+use rustc_hir::attrs::PeImportNameType;
 use rustc_middle::ty::layout::TyAndLayout;
 use rustc_middle::ty::{self, Instance, TyCtxt};
 use rustc_middle::{bug, mir, span_bug};
-use rustc_session::cstore::{DllCallingConvention, DllImport, PeImportNameType};
+use rustc_session::cstore::{DllCallingConvention, DllImport};
 use rustc_span::Span;
 use rustc_target::spec::Target;
 
diff --git a/compiler/rustc_codegen_ssa/src/errors.rs b/compiler/rustc_codegen_ssa/src/errors.rs
index 7ac830bcda9..fb5a8205140 100644
--- a/compiler/rustc_codegen_ssa/src/errors.rs
+++ b/compiler/rustc_codegen_ssa/src/errors.rs
@@ -1121,14 +1121,6 @@ impl IntoDiagArg for ExpectedPointerMutability {
 }
 
 #[derive(Diagnostic)]
-#[diag(codegen_ssa_invalid_no_sanitize)]
-#[note]
-pub(crate) struct InvalidNoSanitize {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
 #[diag(codegen_ssa_target_feature_safe_trait)]
 pub(crate) struct TargetFeatureSafeTrait {
     #[primary_span]
diff --git a/compiler/rustc_codegen_ssa/src/lib.rs b/compiler/rustc_codegen_ssa/src/lib.rs
index 23ed387a3ff..fe0500a5d4c 100644
--- a/compiler/rustc_codegen_ssa/src/lib.rs
+++ b/compiler/rustc_codegen_ssa/src/lib.rs
@@ -25,10 +25,10 @@ use std::io;
 use std::path::{Path, PathBuf};
 use std::sync::Arc;
 
-use rustc_ast as ast;
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
 use rustc_data_structures::unord::UnordMap;
 use rustc_hir::CRATE_HIR_ID;
+use rustc_hir::attrs::{CfgEntry, NativeLibKind};
 use rustc_hir::def_id::CrateNum;
 use rustc_macros::{Decodable, Encodable, HashStable};
 use rustc_metadata::EncodedMetadata;
@@ -45,7 +45,6 @@ use rustc_session::Session;
 use rustc_session::config::{CrateType, OutputFilenames, OutputType, RUST_CGU_EXT};
 use rustc_session::cstore::{self, CrateSource};
 use rustc_session::lint::builtin::LINKER_MESSAGES;
-use rustc_session::utils::NativeLibKind;
 use rustc_span::Symbol;
 
 pub mod assert_module_sources;
@@ -187,7 +186,7 @@ pub struct NativeLib {
     pub kind: NativeLibKind,
     pub name: Symbol,
     pub filename: Option<Symbol>,
-    pub cfg: Option<ast::MetaItemInner>,
+    pub cfg: Option<CfgEntry>,
     pub verbatim: bool,
     pub dll_imports: Vec<cstore::DllImport>,
 }
diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs
index e96590441fa..c3dc3e42b83 100644
--- a/compiler/rustc_codegen_ssa/src/mir/block.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/block.rs
@@ -5,6 +5,7 @@ use rustc_ast as ast;
 use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
 use rustc_data_structures::packed::Pu128;
 use rustc_hir::lang_items::LangItem;
+use rustc_lint_defs::builtin::TAIL_CALL_TRACK_CALLER;
 use rustc_middle::mir::{self, AssertKind, InlineAsmMacro, SwitchTargets, UnwindTerminateReason};
 use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf, ValidityRequirement};
 use rustc_middle::ty::print::{with_no_trimmed_paths, with_no_visible_paths};
@@ -35,7 +36,7 @@ enum MergingSucc {
     True,
 }
 
-/// Indicates to the call terminator codegen whether a cal
+/// Indicates to the call terminator codegen whether a call
 /// is a normal call or an explicit tail call.
 #[derive(Debug, PartialEq)]
 enum CallKind {
@@ -906,7 +907,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                     fn_span,
                 );
 
-                let instance = match instance.def {
+                match instance.def {
                     // We don't need AsyncDropGlueCtorShim here because it is not `noop func`,
                     // it is `func returning noop future`
                     ty::InstanceKind::DropGlue(_, None) => {
@@ -995,14 +996,35 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                                         intrinsic.name,
                                     );
                                 }
-                                instance
+                                (Some(instance), None)
                             }
                         }
                     }
-                    _ => instance,
-                };
 
-                (Some(instance), None)
+                    _ if kind == CallKind::Tail
+                        && instance.def.requires_caller_location(bx.tcx()) =>
+                    {
+                        if let Some(hir_id) =
+                            terminator.source_info.scope.lint_root(&self.mir.source_scopes)
+                        {
+                            let msg = "tail calling a function marked with `#[track_caller]` has no special effect";
+                            bx.tcx().node_lint(TAIL_CALL_TRACK_CALLER, hir_id, |d| {
+                                _ = d.primary_message(msg).span(fn_span)
+                            });
+                        }
+
+                        let instance = ty::Instance::resolve_for_fn_ptr(
+                            bx.tcx(),
+                            bx.typing_env(),
+                            def_id,
+                            generic_args,
+                        )
+                        .unwrap();
+
+                        (None, Some(bx.get_fn_addr(instance)))
+                    }
+                    _ => (Some(instance), None),
+                }
             }
             ty::FnPtr(..) => (None, Some(callee.immediate())),
             _ => bug!("{} is not callable", callee.layout.ty),
diff --git a/compiler/rustc_codegen_ssa/src/mir/naked_asm.rs b/compiler/rustc_codegen_ssa/src/mir/naked_asm.rs
index 2a9b5c9019b..31784cabf4a 100644
--- a/compiler/rustc_codegen_ssa/src/mir/naked_asm.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/naked_asm.rs
@@ -1,6 +1,6 @@
 use rustc_abi::{BackendRepr, Float, Integer, Primitive, RegKind};
-use rustc_hir::attrs::InstructionSetAttr;
-use rustc_middle::mir::mono::{Linkage, MonoItemData, Visibility};
+use rustc_hir::attrs::{InstructionSetAttr, Linkage};
+use rustc_middle::mir::mono::{MonoItemData, Visibility};
 use rustc_middle::mir::{InlineAsmOperand, START_BLOCK};
 use rustc_middle::ty::layout::{FnAbiOf, LayoutOf, TyAndLayout};
 use rustc_middle::ty::{Instance, Ty, TyCtxt, TypeVisitableExt};
diff --git a/compiler/rustc_codegen_ssa/src/mono_item.rs b/compiler/rustc_codegen_ssa/src/mono_item.rs
index b9040c330fb..8f03dc1e6b5 100644
--- a/compiler/rustc_codegen_ssa/src/mono_item.rs
+++ b/compiler/rustc_codegen_ssa/src/mono_item.rs
@@ -1,5 +1,6 @@
+use rustc_hir::attrs::Linkage;
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
-use rustc_middle::mir::mono::{Linkage, MonoItem, MonoItemData, Visibility};
+use rustc_middle::mir::mono::{MonoItem, MonoItemData, Visibility};
 use rustc_middle::ty::layout::HasTyCtxt;
 use tracing::debug;
 
diff --git a/compiler/rustc_codegen_ssa/src/target_features.rs b/compiler/rustc_codegen_ssa/src/target_features.rs
index 7e4341a8236..54584999d61 100644
--- a/compiler/rustc_codegen_ssa/src/target_features.rs
+++ b/compiler/rustc_codegen_ssa/src/target_features.rs
@@ -3,7 +3,7 @@ use rustc_data_structures::unord::{UnordMap, UnordSet};
 use rustc_hir::attrs::InstructionSetAttr;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LOCAL_CRATE, LocalDefId};
-use rustc_middle::middle::codegen_fn_attrs::TargetFeature;
+use rustc_middle::middle::codegen_fn_attrs::{TargetFeature, TargetFeatureKind};
 use rustc_middle::query::Providers;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::Session;
@@ -22,6 +22,7 @@ pub(crate) fn from_target_feature_attr(
     tcx: TyCtxt<'_>,
     did: LocalDefId,
     features: &[(Symbol, Span)],
+    was_forced: bool,
     rust_target_features: &UnordMap<String, target_features::Stability>,
     target_features: &mut Vec<TargetFeature>,
 ) {
@@ -88,7 +89,14 @@ pub(crate) fn from_target_feature_attr(
                         }
                     }
                 }
-                target_features.push(TargetFeature { name, implied: name != feature })
+                let kind = if name != feature {
+                    TargetFeatureKind::Implied
+                } else if was_forced {
+                    TargetFeatureKind::Forced
+                } else {
+                    TargetFeatureKind::Enabled
+                };
+                target_features.push(TargetFeature { name, kind })
             }
         }
     }
@@ -180,6 +188,7 @@ fn parse_rust_feature_flag<'a>(
             while let Some(new_feature) = new_features.pop() {
                 if features.insert(new_feature) {
                     if let Some(implied_features) = inverse_implied_features.get(&new_feature) {
+                        #[allow(rustc::potential_query_instability)]
                         new_features.extend(implied_features)
                     }
                 }
diff --git a/compiler/rustc_codegen_ssa/src/traits/declare.rs b/compiler/rustc_codegen_ssa/src/traits/declare.rs
index 9f735546558..8d5f0a5b939 100644
--- a/compiler/rustc_codegen_ssa/src/traits/declare.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/declare.rs
@@ -1,5 +1,6 @@
+use rustc_hir::attrs::Linkage;
 use rustc_hir::def_id::DefId;
-use rustc_middle::mir::mono::{Linkage, Visibility};
+use rustc_middle::mir::mono::Visibility;
 use rustc_middle::ty::Instance;
 
 pub trait PreDefineCodegenMethods<'tcx> {
diff --git a/compiler/rustc_codegen_ssa/src/traits/write.rs b/compiler/rustc_codegen_ssa/src/traits/write.rs
index f391c198e1a..cc7c4e46d7b 100644
--- a/compiler/rustc_codegen_ssa/src/traits/write.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/write.rs
@@ -1,7 +1,6 @@
 use std::path::PathBuf;
 
-use rustc_ast::expand::autodiff_attrs::AutoDiffItem;
-use rustc_errors::{DiagCtxtHandle, FatalError};
+use rustc_errors::DiagCtxtHandle;
 use rustc_middle::dep_graph::WorkProduct;
 
 use crate::back::lto::{SerializedModule, ThinModule};
@@ -23,8 +22,7 @@ pub trait WriteBackendMethods: Clone + 'static {
         exported_symbols_for_lto: &[String],
         each_linked_rlib_for_lto: &[PathBuf],
         modules: Vec<FatLtoInput<Self>>,
-        diff_fncs: Vec<AutoDiffItem>,
-    ) -> Result<ModuleCodegen<Self::Module>, FatalError>;
+    ) -> ModuleCodegen<Self::Module>;
     /// Performs thin LTO by performing necessary global analysis and returning two
     /// lists, one of the modules that need optimization and another for modules that
     /// can simply be copied over from the incr. comp. cache.
@@ -34,7 +32,7 @@ pub trait WriteBackendMethods: Clone + 'static {
         each_linked_rlib_for_lto: &[PathBuf],
         modules: Vec<(String, Self::ThinBuffer)>,
         cached_modules: Vec<(SerializedModule<Self::ModuleBuffer>, WorkProduct)>,
-    ) -> Result<(Vec<ThinModule<Self>>, Vec<WorkProduct>), FatalError>;
+    ) -> (Vec<ThinModule<Self>>, Vec<WorkProduct>);
     fn print_pass_timings(&self);
     fn print_statistics(&self);
     fn optimize(
@@ -42,16 +40,16 @@ pub trait WriteBackendMethods: Clone + 'static {
         dcx: DiagCtxtHandle<'_>,
         module: &mut ModuleCodegen<Self::Module>,
         config: &ModuleConfig,
-    ) -> Result<(), FatalError>;
+    );
     fn optimize_thin(
         cgcx: &CodegenContext<Self>,
         thin: ThinModule<Self>,
-    ) -> Result<ModuleCodegen<Self::Module>, FatalError>;
+    ) -> ModuleCodegen<Self::Module>;
     fn codegen(
         cgcx: &CodegenContext<Self>,
         module: ModuleCodegen<Self::Module>,
         config: &ModuleConfig,
-    ) -> Result<CompiledModule, FatalError>;
+    ) -> CompiledModule;
     fn prepare_thin(
         module: ModuleCodegen<Self::Module>,
         want_summary: bool,
diff --git a/compiler/rustc_const_eval/Cargo.toml b/compiler/rustc_const_eval/Cargo.toml
index 51dcee8d882..88dfc83f7fc 100644
--- a/compiler/rustc_const_eval/Cargo.toml
+++ b/compiler/rustc_const_eval/Cargo.toml
@@ -22,5 +22,5 @@ rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 rustc_trait_selection = { path = "../rustc_trait_selection" }
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_const_eval/messages.ftl b/compiler/rustc_const_eval/messages.ftl
index 2985eafb63a..60518dafbf2 100644
--- a/compiler/rustc_const_eval/messages.ftl
+++ b/compiler/rustc_const_eval/messages.ftl
@@ -57,7 +57,7 @@ const_eval_const_context = {$kind ->
 }
 
 const_eval_const_heap_ptr_in_final = encountered `const_allocate` pointer in final value that was not made global
-    .note = use `const_make_global` to make allocated pointers immutable before returning
+    .note = use `const_make_global` to turn allocated pointers into immutable globals before returning
 
 const_eval_const_make_global_ptr_already_made_global = attempting to call `const_make_global` twice on the same allocation {$alloc}
 
@@ -231,6 +231,9 @@ const_eval_mutable_borrow_escaping =
 
 const_eval_mutable_ptr_in_final = encountered mutable pointer in final value of {const_eval_intern_kind}
 
+const_eval_partial_pointer_in_final = encountered partial pointer in final value of {const_eval_intern_kind}
+    .note = while pointers can be broken apart into individual bytes during const-evaluation, only complete pointers (with all their bytes in the right order) are supported in the final value
+
 const_eval_nested_static_in_thread_local = #[thread_local] does not support implicit nested statics, please create explicit static items and refer to them instead
 
 const_eval_non_const_await =
@@ -299,10 +302,8 @@ const_eval_panic = evaluation panicked: {$msg}
 
 const_eval_panic_non_str = argument to `panic!()` in a const context must have type `&str`
 
-const_eval_partial_pointer_copy =
-    unable to copy parts of a pointer from memory at {$ptr}
-const_eval_partial_pointer_overwrite =
-    unable to overwrite parts of a pointer in memory at {$ptr}
+const_eval_partial_pointer_read =
+    unable to read parts of a pointer from memory at {$ptr}
 const_eval_pointer_arithmetic_overflow =
     overflowing pointer arithmetic: the total offset in bytes does not fit in an `isize`
 
diff --git a/compiler/rustc_const_eval/src/check_consts/check.rs b/compiler/rustc_const_eval/src/check_consts/check.rs
index 8e2c138282a..ca707b50d50 100644
--- a/compiler/rustc_const_eval/src/check_consts/check.rs
+++ b/compiler/rustc_const_eval/src/check_consts/check.rs
@@ -827,7 +827,7 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
 
                 // At this point, we are calling a function, `callee`, whose `DefId` is known...
 
-                // `begin_panic` and `#[rustc_const_panic_str]` functions accept generic
+                // `begin_panic` and `panic_display` functions accept generic
                 // types other than str. Check to enforce that only str can be used in
                 // const-eval.
 
@@ -841,8 +841,8 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
                     return;
                 }
 
-                // const-eval of `#[rustc_const_panic_str]` functions assumes the argument is `&&str`
-                if tcx.has_attr(callee, sym::rustc_const_panic_str) {
+                // const-eval of `panic_display` assumes the argument is `&&str`
+                if tcx.is_lang_item(callee, LangItem::PanicDisplay) {
                     match args[0].node.ty(&self.ccx.body.local_decls, tcx).kind() {
                         ty::Ref(_, ty, _) if matches!(ty.kind(), ty::Ref(_, ty, _) if ty.is_str()) =>
                             {}
diff --git a/compiler/rustc_const_eval/src/const_eval/eval_queries.rs b/compiler/rustc_const_eval/src/const_eval/eval_queries.rs
index 5835660e1c3..4da2663319c 100644
--- a/compiler/rustc_const_eval/src/const_eval/eval_queries.rs
+++ b/compiler/rustc_const_eval/src/const_eval/eval_queries.rs
@@ -117,6 +117,13 @@ fn eval_body_using_ecx<'tcx, R: InterpretationResult<'tcx>>(
                 ecx.tcx.dcx().emit_err(errors::ConstHeapPtrInFinal { span: ecx.tcx.span }),
             )));
         }
+        Err(InternError::PartialPointer) => {
+            throw_inval!(AlreadyReported(ReportedErrorInfo::non_const_eval_error(
+                ecx.tcx
+                    .dcx()
+                    .emit_err(errors::PartialPtrInFinal { span: ecx.tcx.span, kind: intern_kind }),
+            )));
+        }
     }
 
     interp_ok(R::make_result(ret, ecx))
diff --git a/compiler/rustc_const_eval/src/const_eval/machine.rs b/compiler/rustc_const_eval/src/const_eval/machine.rs
index a18ae79f318..fccb6b171b1 100644
--- a/compiler/rustc_const_eval/src/const_eval/machine.rs
+++ b/compiler/rustc_const_eval/src/const_eval/machine.rs
@@ -237,7 +237,7 @@ impl<'tcx> CompileTimeInterpCx<'tcx> {
     ) -> InterpResult<'tcx, Option<ty::Instance<'tcx>>> {
         let def_id = instance.def_id();
 
-        if self.tcx.has_attr(def_id, sym::rustc_const_panic_str)
+        if self.tcx.is_lang_item(def_id, LangItem::PanicDisplay)
             || self.tcx.is_lang_item(def_id, LangItem::BeginPanic)
         {
             let args = self.copy_fn_args(args);
@@ -280,22 +280,110 @@ impl<'tcx> CompileTimeInterpCx<'tcx> {
         interp_ok(match (a, b) {
             // Comparisons between integers are always known.
             (Scalar::Int(a), Scalar::Int(b)) => (a == b) as u8,
-            // Comparisons of null with an arbitrary scalar can be known if `scalar_may_be_null`
-            // indicates that the scalar can definitely *not* be null.
-            (Scalar::Int(int), ptr) | (ptr, Scalar::Int(int))
-                if int.is_null() && !self.scalar_may_be_null(ptr)? =>
-            {
-                0
+            // Comparing a pointer `ptr` with an integer `int` is equivalent to comparing
+            // `ptr-int` with null, so we can reduce this case to a `scalar_may_be_null` test.
+            (Scalar::Int(int), Scalar::Ptr(ptr, _)) | (Scalar::Ptr(ptr, _), Scalar::Int(int)) => {
+                let int = int.to_target_usize(*self.tcx);
+                // The `wrapping_neg` here may produce a value that is not
+                // a valid target usize any more... but `wrapping_offset` handles that correctly.
+                let offset_ptr = ptr.wrapping_offset(Size::from_bytes(int.wrapping_neg()), self);
+                if !self.scalar_may_be_null(Scalar::from_pointer(offset_ptr, self))? {
+                    // `ptr.wrapping_sub(int)` is definitely not equal to `0`, so `ptr != int`
+                    0
+                } else {
+                    // `ptr.wrapping_sub(int)` could be equal to `0`, but might not be,
+                    // so we cannot know for sure if `ptr == int` or not
+                    2
+                }
+            }
+            (Scalar::Ptr(a, _), Scalar::Ptr(b, _)) => {
+                let (a_prov, a_offset) = a.prov_and_relative_offset();
+                let (b_prov, b_offset) = b.prov_and_relative_offset();
+                let a_allocid = a_prov.alloc_id();
+                let b_allocid = b_prov.alloc_id();
+                let a_info = self.get_alloc_info(a_allocid);
+                let b_info = self.get_alloc_info(b_allocid);
+
+                // Check if the pointers cannot be equal due to alignment
+                if a_info.align > Align::ONE && b_info.align > Align::ONE {
+                    let min_align = Ord::min(a_info.align.bytes(), b_info.align.bytes());
+                    let a_residue = a_offset.bytes() % min_align;
+                    let b_residue = b_offset.bytes() % min_align;
+                    if a_residue != b_residue {
+                        // If the two pointers have a different residue modulo their
+                        // common alignment, they cannot be equal.
+                        return interp_ok(0);
+                    }
+                    // The pointers have the same residue modulo their common alignment,
+                    // so they could be equal. Try the other checks.
+                }
+
+                if let (Some(GlobalAlloc::Static(a_did)), Some(GlobalAlloc::Static(b_did))) = (
+                    self.tcx.try_get_global_alloc(a_allocid),
+                    self.tcx.try_get_global_alloc(b_allocid),
+                ) {
+                    if a_allocid == b_allocid {
+                        debug_assert_eq!(
+                            a_did, b_did,
+                            "different static item DefIds had same AllocId? {a_allocid:?} == {b_allocid:?}, {a_did:?} != {b_did:?}"
+                        );
+                        // Comparing two pointers into the same static. As per
+                        // https://doc.rust-lang.org/nightly/reference/items/static-items.html#r-items.static.intro
+                        // a static cannot be duplicated, so if two pointers are into the same
+                        // static, they are equal if and only if their offsets are equal.
+                        (a_offset == b_offset) as u8
+                    } else {
+                        debug_assert_ne!(
+                            a_did, b_did,
+                            "same static item DefId had two different AllocIds? {a_allocid:?} != {b_allocid:?}, {a_did:?} == {b_did:?}"
+                        );
+                        // Comparing two pointers into the different statics.
+                        // We can never determine for sure that two pointers into different statics
+                        // are *equal*, but we can know that they are *inequal* if they are both
+                        // strictly in-bounds (i.e. in-bounds and not one-past-the-end) of
+                        // their respective static, as different non-zero-sized statics cannot
+                        // overlap or be deduplicated as per
+                        // https://doc.rust-lang.org/nightly/reference/items/static-items.html#r-items.static.intro
+                        // (non-deduplication), and
+                        // https://doc.rust-lang.org/nightly/reference/items/static-items.html#r-items.static.storage-disjointness
+                        // (non-overlapping).
+                        if a_offset < a_info.size && b_offset < b_info.size {
+                            0
+                        } else {
+                            // Otherwise, conservatively say we don't know.
+                            // There are some cases we could still return `0` for, e.g.
+                            // if the pointers being equal would require their statics to overlap
+                            // one or more bytes, but for simplicity we currently only check
+                            // strictly in-bounds pointers.
+                            2
+                        }
+                    }
+                } else {
+                    // All other cases we conservatively say we don't know.
+                    //
+                    // For comparing statics to non-statics, as per https://doc.rust-lang.org/nightly/reference/items/static-items.html#r-items.static.storage-disjointness
+                    // immutable statics can overlap with other kinds of allocations sometimes.
+                    //
+                    // FIXME: We could be more decisive for (non-zero-sized) mutable statics,
+                    // which cannot overlap with other kinds of allocations.
+                    //
+                    // Functions and vtables can be duplicated and deduplicated, so we
+                    // cannot be sure of runtime equality of pointers to the same one, or the
+                    // runtime inequality of pointers to different ones (see e.g. #73722),
+                    // so comparing those should return 2, whether they are the same allocation
+                    // or not.
+                    //
+                    // `GlobalAlloc::TypeId` exists mostly to prevent consteval from comparing
+                    // `TypeId`s, so comparing those should always return 2, whether they are the
+                    // same allocation or not.
+                    //
+                    // FIXME: We could revisit comparing pointers into the same
+                    // `GlobalAlloc::Memory` once https://github.com/rust-lang/rust/issues/128775
+                    // is fixed (but they can be deduplicated, so comparing pointers into different
+                    // ones should return 2).
+                    2
+                }
             }
-            // Other ways of comparing integers and pointers can never be known for sure.
-            (Scalar::Int { .. }, Scalar::Ptr(..)) | (Scalar::Ptr(..), Scalar::Int { .. }) => 2,
-            // FIXME: return a `1` for when both sides are the same pointer, *except* that
-            // some things (like functions and vtables) do not have stable addresses
-            // so we need to be careful around them (see e.g. #73722).
-            // FIXME: return `0` for at least some comparisons where we can reliably
-            // determine the result of runtime inequality tests at compile-time.
-            // Examples include comparison of addresses in different static items.
-            (Scalar::Ptr(..), Scalar::Ptr(..)) => 2,
         })
     }
 }
diff --git a/compiler/rustc_const_eval/src/errors.rs b/compiler/rustc_const_eval/src/errors.rs
index a4148cb145f..2d412ee5ec2 100644
--- a/compiler/rustc_const_eval/src/errors.rs
+++ b/compiler/rustc_const_eval/src/errors.rs
@@ -52,6 +52,15 @@ pub(crate) struct ConstHeapPtrInFinal {
 }
 
 #[derive(Diagnostic)]
+#[diag(const_eval_partial_pointer_in_final)]
+#[note]
+pub(crate) struct PartialPtrInFinal {
+    #[primary_span]
+    pub span: Span,
+    pub kind: InternKind,
+}
+
+#[derive(Diagnostic)]
 #[diag(const_eval_unstable_in_stable_exposed)]
 pub(crate) struct UnstableInStableExposed {
     pub gate: String,
@@ -836,8 +845,7 @@ impl ReportErrorExt for UnsupportedOpInfo {
             UnsupportedOpInfo::Unsupported(s) => s.clone().into(),
             UnsupportedOpInfo::ExternTypeField => const_eval_extern_type_field,
             UnsupportedOpInfo::UnsizedLocal => const_eval_unsized_local,
-            UnsupportedOpInfo::OverwritePartialPointer(_) => const_eval_partial_pointer_overwrite,
-            UnsupportedOpInfo::ReadPartialPointer(_) => const_eval_partial_pointer_copy,
+            UnsupportedOpInfo::ReadPartialPointer(_) => const_eval_partial_pointer_read,
             UnsupportedOpInfo::ReadPointerAsInt(_) => const_eval_read_pointer_as_int,
             UnsupportedOpInfo::ThreadLocalStatic(_) => const_eval_thread_local_static,
             UnsupportedOpInfo::ExternStatic(_) => const_eval_extern_static,
@@ -848,7 +856,7 @@ impl ReportErrorExt for UnsupportedOpInfo {
         use UnsupportedOpInfo::*;
 
         use crate::fluent_generated::*;
-        if let ReadPointerAsInt(_) | OverwritePartialPointer(_) | ReadPartialPointer(_) = self {
+        if let ReadPointerAsInt(_) | ReadPartialPointer(_) = self {
             diag.help(const_eval_ptr_as_bytes_1);
             diag.help(const_eval_ptr_as_bytes_2);
         }
@@ -860,7 +868,7 @@ impl ReportErrorExt for UnsupportedOpInfo {
             | UnsupportedOpInfo::ExternTypeField
             | Unsupported(_)
             | ReadPointerAsInt(_) => {}
-            OverwritePartialPointer(ptr) | ReadPartialPointer(ptr) => {
+            ReadPartialPointer(ptr) => {
                 diag.arg("ptr", ptr);
             }
             ThreadLocalStatic(did) | ExternStatic(did) => rustc_middle::ty::tls::with(|tcx| {
diff --git a/compiler/rustc_const_eval/src/interpret/call.rs b/compiler/rustc_const_eval/src/interpret/call.rs
index b1cc0cc2878..4cb88d44e1b 100644
--- a/compiler/rustc_const_eval/src/interpret/call.rs
+++ b/compiler/rustc_const_eval/src/interpret/call.rs
@@ -27,8 +27,9 @@ use crate::{enter_trace_span, fluent_generated as fluent};
 pub enum FnArg<'tcx, Prov: Provenance = CtfeProvenance> {
     /// Pass a copy of the given operand.
     Copy(OpTy<'tcx, Prov>),
-    /// Allow for the argument to be passed in-place: destroy the value originally stored at that place and
-    /// make the place inaccessible for the duration of the function call.
+    /// Allow for the argument to be passed in-place: destroy the value originally stored at that
+    /// place and make the place inaccessible for the duration of the function call. This *must* be
+    /// an in-memory place so that we can do the proper alias checks.
     InPlace(MPlaceTy<'tcx, Prov>),
 }
 
@@ -379,6 +380,11 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
             }
         }
 
+        // *Before* pushing the new frame, determine whether the return destination is in memory.
+        // Need to use `place_to_op` to be *sure* we get the mplace if there is one.
+        let destination_mplace = self.place_to_op(destination)?.as_mplace_or_imm().left();
+
+        // Push the "raw" frame -- this leaves locals uninitialized.
         self.push_stack_frame_raw(instance, body, destination, cont)?;
 
         // If an error is raised here, pop the frame again to get an accurate backtrace.
@@ -496,7 +502,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
 
             // Protect return place for in-place return value passing.
             // We only need to protect anything if this is actually an in-memory place.
-            if let Left(mplace) = destination.as_mplace_or_local() {
+            if let Some(mplace) = destination_mplace {
                 M::protect_in_place_function_argument(self, &mplace)?;
             }
 
@@ -731,18 +737,21 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
     ) {
         let tcx = *self.tcx;
 
-        let trait_def_id = tcx.trait_of_assoc(def_id).unwrap();
+        let trait_def_id = tcx.parent(def_id);
         let virtual_trait_ref = ty::TraitRef::from_assoc(tcx, trait_def_id, virtual_instance.args);
         let existential_trait_ref = ty::ExistentialTraitRef::erase_self_ty(tcx, virtual_trait_ref);
         let concrete_trait_ref = existential_trait_ref.with_self_ty(tcx, dyn_ty);
 
-        let concrete_method = Instance::expect_resolve_for_vtable(
-            tcx,
-            self.typing_env,
-            def_id,
-            virtual_instance.args.rebase_onto(tcx, trait_def_id, concrete_trait_ref.args),
-            self.cur_span(),
-        );
+        let concrete_method = {
+            let _trace = enter_trace_span!(M, resolve::expect_resolve_for_vtable, ?def_id);
+            Instance::expect_resolve_for_vtable(
+                tcx,
+                self.typing_env,
+                def_id,
+                virtual_instance.args.rebase_onto(tcx, trait_def_id, concrete_trait_ref.args),
+                self.cur_span(),
+            )
+        };
         assert_eq!(concrete_instance, concrete_method);
     }
 
@@ -825,7 +834,11 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 place
             }
         };
-        let instance = ty::Instance::resolve_drop_in_place(*self.tcx, place.layout.ty);
+        let instance = {
+            let _trace =
+                enter_trace_span!(M, resolve::resolve_drop_in_place, ty = ?place.layout.ty);
+            ty::Instance::resolve_drop_in_place(*self.tcx, place.layout.ty)
+        };
         let fn_abi = self.fn_abi_of_instance(instance, ty::List::empty())?;
 
         let arg = self.mplace_to_ref(&place)?;
diff --git a/compiler/rustc_const_eval/src/interpret/cast.rs b/compiler/rustc_const_eval/src/interpret/cast.rs
index de4fbc7b475..e3afeda5b7c 100644
--- a/compiler/rustc_const_eval/src/interpret/cast.rs
+++ b/compiler/rustc_const_eval/src/interpret/cast.rs
@@ -16,8 +16,8 @@ use super::{
     FnVal, ImmTy, Immediate, InterpCx, Machine, OpTy, PlaceTy, err_inval, interp_ok, throw_ub,
     throw_ub_custom,
 };
-use crate::fluent_generated as fluent;
 use crate::interpret::Writeable;
+use crate::{enter_trace_span, fluent_generated as fluent};
 
 impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
     pub fn cast(
@@ -81,13 +81,16 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 // The src operand does not matter, just its type
                 match *src.layout.ty.kind() {
                     ty::FnDef(def_id, args) => {
-                        let instance = ty::Instance::resolve_for_fn_ptr(
-                            *self.tcx,
-                            self.typing_env,
-                            def_id,
-                            args,
-                        )
-                        .ok_or_else(|| err_inval!(TooGeneric))?;
+                        let instance = {
+                            let _trace = enter_trace_span!(M, resolve::resolve_for_fn_ptr, ?def_id);
+                            ty::Instance::resolve_for_fn_ptr(
+                                *self.tcx,
+                                self.typing_env,
+                                def_id,
+                                args,
+                            )
+                            .ok_or_else(|| err_inval!(TooGeneric))?
+                        };
 
                         let fn_ptr = self.fn_ptr(FnVal::Instance(instance));
                         self.write_pointer(fn_ptr, dest)?;
@@ -114,12 +117,15 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 // The src operand does not matter, just its type
                 match *src.layout.ty.kind() {
                     ty::Closure(def_id, args) => {
-                        let instance = ty::Instance::resolve_closure(
-                            *self.tcx,
-                            def_id,
-                            args,
-                            ty::ClosureKind::FnOnce,
-                        );
+                        let instance = {
+                            let _trace = enter_trace_span!(M, resolve::resolve_closure, ?def_id);
+                            ty::Instance::resolve_closure(
+                                *self.tcx,
+                                def_id,
+                                args,
+                                ty::ClosureKind::FnOnce,
+                            )
+                        };
                         let fn_ptr = self.fn_ptr(FnVal::Instance(instance));
                         self.write_pointer(fn_ptr, dest)?;
                     }
diff --git a/compiler/rustc_const_eval/src/interpret/eval_context.rs b/compiler/rustc_const_eval/src/interpret/eval_context.rs
index d4f2bb8257d..9681d89ce35 100644
--- a/compiler/rustc_const_eval/src/interpret/eval_context.rs
+++ b/compiler/rustc_const_eval/src/interpret/eval_context.rs
@@ -325,8 +325,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         let _trace = enter_trace_span!(
             M,
             "instantiate_from_frame_and_normalize_erasing_regions",
-            "{}",
-            frame.instance
+            %frame.instance
         );
         frame
             .instance
@@ -344,6 +343,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         def: DefId,
         args: GenericArgsRef<'tcx>,
     ) -> InterpResult<'tcx, ty::Instance<'tcx>> {
+        let _trace = enter_trace_span!(M, resolve::try_resolve, def = ?def);
         trace!("resolve: {:?}, {:#?}", def, args);
         trace!("typing_env: {:#?}", self.typing_env);
         trace!("args: {:#?}", args);
@@ -582,6 +582,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         span: Span,
         layout: Option<TyAndLayout<'tcx>>,
     ) -> InterpResult<'tcx, OpTy<'tcx, M::Provenance>> {
+        let _trace = enter_trace_span!(M, const_eval::eval_mir_constant, ?val);
         let const_val = val.eval(*self.tcx, self.typing_env, span).map_err(|err| {
                 if M::ALL_CONSTS_ARE_PRECHECKED {
                     match err {
diff --git a/compiler/rustc_const_eval/src/interpret/intern.rs b/compiler/rustc_const_eval/src/interpret/intern.rs
index bb59b9f5418..5d510a98352 100644
--- a/compiler/rustc_const_eval/src/interpret/intern.rs
+++ b/compiler/rustc_const_eval/src/interpret/intern.rs
@@ -19,9 +19,12 @@ use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
 use rustc_hir as hir;
 use rustc_hir::definitions::{DefPathData, DisambiguatorState};
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
-use rustc_middle::mir::interpret::{ConstAllocation, CtfeProvenance, InterpResult};
+use rustc_middle::mir::interpret::{
+    AllocBytes, ConstAllocation, CtfeProvenance, InterpResult, Provenance,
+};
 use rustc_middle::query::TyCtxtAt;
 use rustc_middle::span_bug;
+use rustc_middle::ty::TyCtxt;
 use rustc_middle::ty::layout::TyAndLayout;
 use rustc_span::def_id::LocalDefId;
 use tracing::{instrument, trace};
@@ -52,39 +55,30 @@ impl HasStaticRootDefId for const_eval::CompileTimeMachine<'_> {
     }
 }
 
-/// Intern an allocation. Returns `Err` if the allocation does not exist in the local memory.
-///
-/// `mutability` can be used to force immutable interning: if it is `Mutability::Not`, the
-/// allocation is interned immutably; if it is `Mutability::Mut`, then the allocation *must be*
-/// already mutable (as a sanity check).
-///
-/// Returns an iterator over all relocations referred to by this allocation.
-fn intern_shallow<'tcx, M: CompileTimeMachine<'tcx>>(
-    ecx: &mut InterpCx<'tcx, M>,
-    alloc_id: AllocId,
+fn prepare_alloc<'tcx, Prov: Provenance, Extra, Bytes: AllocBytes>(
+    tcx: TyCtxt<'tcx>,
+    kind: MemoryKind<const_eval::MemoryKind>,
+    alloc: &mut Allocation<Prov, Extra, Bytes>,
     mutability: Mutability,
-    disambiguator: Option<&mut DisambiguatorState>,
-) -> Result<impl Iterator<Item = CtfeProvenance> + 'tcx, InternError> {
-    trace!("intern_shallow {:?}", alloc_id);
-    // remove allocation
-    // FIXME(#120456) - is `swap_remove` correct?
-    let Some((kind, mut alloc)) = ecx.memory.alloc_map.swap_remove(&alloc_id) else {
-        return Err(InternError::DanglingPointer);
-    };
-
+) -> Result<(), InternError> {
     match kind {
         MemoryKind::Machine(const_eval::MemoryKind::Heap { was_made_global }) => {
             if !was_made_global {
                 // Attempting to intern a `const_allocate`d pointer that was not made global via
-                // `const_make_global`. We want to error here, but we have to first put the
-                // allocation back into the `alloc_map` to keep things in a consistent state.
-                ecx.memory.alloc_map.insert(alloc_id, (kind, alloc));
+                // `const_make_global`.
+                tcx.dcx().delayed_bug("non-global heap allocation in const value");
                 return Err(InternError::ConstAllocNotGlobal);
             }
         }
         MemoryKind::Stack | MemoryKind::CallerLocation => {}
     }
 
+    if !alloc.provenance_merge_bytes(&tcx) {
+        // Per-byte provenance is not supported by backends, so we cannot accept it here.
+        tcx.dcx().delayed_bug("partial pointer in const value");
+        return Err(InternError::PartialPointer);
+    }
+
     // Set allocation mutability as appropriate. This is used by LLVM to put things into
     // read-only memory, and also by Miri when evaluating other globals that
     // access this one.
@@ -97,6 +91,36 @@ fn intern_shallow<'tcx, M: CompileTimeMachine<'tcx>>(
             assert_eq!(alloc.mutability, Mutability::Mut);
         }
     }
+    Ok(())
+}
+
+/// Intern an allocation. Returns `Err` if the allocation does not exist in the local memory.
+///
+/// `mutability` can be used to force immutable interning: if it is `Mutability::Not`, the
+/// allocation is interned immutably; if it is `Mutability::Mut`, then the allocation *must be*
+/// already mutable (as a sanity check).
+///
+/// Returns an iterator over all relocations referred to by this allocation.
+fn intern_shallow<'tcx, M: CompileTimeMachine<'tcx>>(
+    ecx: &mut InterpCx<'tcx, M>,
+    alloc_id: AllocId,
+    mutability: Mutability,
+    disambiguator: Option<&mut DisambiguatorState>,
+) -> Result<impl Iterator<Item = CtfeProvenance> + 'tcx, InternError> {
+    trace!("intern_shallow {:?}", alloc_id);
+    // remove allocation
+    // FIXME(#120456) - is `swap_remove` correct?
+    let Some((kind, mut alloc)) = ecx.memory.alloc_map.swap_remove(&alloc_id) else {
+        return Err(InternError::DanglingPointer);
+    };
+
+    if let Err(err) = prepare_alloc(*ecx.tcx, kind, &mut alloc, mutability) {
+        // We want to error here, but we have to first put the
+        // allocation back into the `alloc_map` to keep things in a consistent state.
+        ecx.memory.alloc_map.insert(alloc_id, (kind, alloc));
+        return Err(err);
+    }
+
     // link the alloc id to the actual allocation
     let alloc = ecx.tcx.mk_const_alloc(alloc);
     if let Some(static_id) = ecx.machine.static_def_id() {
@@ -166,6 +190,7 @@ pub enum InternError {
     BadMutablePointer,
     DanglingPointer,
     ConstAllocNotGlobal,
+    PartialPointer,
 }
 
 /// Intern `ret` and everything it references.
@@ -221,13 +246,11 @@ pub fn intern_const_alloc_recursive<'tcx, M: CompileTimeMachine<'tcx>>(
     let mut todo: Vec<_> = if is_static {
         // Do not steal the root allocation, we need it later to create the return value of `eval_static_initializer`.
         // But still change its mutability to match the requested one.
-        let alloc = ecx.memory.alloc_map.get_mut(&base_alloc_id).unwrap();
-        alloc.1.mutability = base_mutability;
-        alloc.1.provenance().ptrs().iter().map(|&(_, prov)| prov).collect()
+        let (kind, alloc) = ecx.memory.alloc_map.get_mut(&base_alloc_id).unwrap();
+        prepare_alloc(*ecx.tcx, *kind, alloc, base_mutability)?;
+        alloc.provenance().ptrs().iter().map(|&(_, prov)| prov).collect()
     } else {
-        intern_shallow(ecx, base_alloc_id, base_mutability, Some(&mut disambiguator))
-            .unwrap()
-            .collect()
+        intern_shallow(ecx, base_alloc_id, base_mutability, Some(&mut disambiguator))?.collect()
     };
     // We need to distinguish "has just been interned" from "was already in `tcx`",
     // so we track this in a separate set.
@@ -235,7 +258,6 @@ pub fn intern_const_alloc_recursive<'tcx, M: CompileTimeMachine<'tcx>>(
     // Whether we encountered a bad mutable pointer.
     // We want to first report "dangling" and then "mutable", so we need to delay reporting these
     // errors.
-    let mut result = Ok(());
     let mut found_bad_mutable_ptr = false;
 
     // Keep interning as long as there are things to intern.
@@ -310,20 +332,15 @@ pub fn intern_const_alloc_recursive<'tcx, M: CompileTimeMachine<'tcx>>(
         // okay with losing some potential for immutability here. This can anyway only affect
         // `static mut`.
         just_interned.insert(alloc_id);
-        match intern_shallow(ecx, alloc_id, inner_mutability, Some(&mut disambiguator)) {
-            Ok(nested) => todo.extend(nested),
-            Err(err) => {
-                ecx.tcx.dcx().delayed_bug("error during const interning");
-                result = Err(err);
-            }
-        }
+        let next = intern_shallow(ecx, alloc_id, inner_mutability, Some(&mut disambiguator))?;
+        todo.extend(next);
     }
-    if found_bad_mutable_ptr && result.is_ok() {
+    if found_bad_mutable_ptr {
         // We found a mutable pointer inside a const where inner allocations should be immutable,
         // and there was no other error. This should usually never happen! However, this can happen
         // in unleash-miri mode, so report it as a normal error then.
         if ecx.tcx.sess.opts.unstable_opts.unleash_the_miri_inside_of_you {
-            result = Err(InternError::BadMutablePointer);
+            return Err(InternError::BadMutablePointer);
         } else {
             span_bug!(
                 ecx.tcx.span,
@@ -331,7 +348,7 @@ pub fn intern_const_alloc_recursive<'tcx, M: CompileTimeMachine<'tcx>>(
             );
         }
     }
-    result
+    Ok(())
 }
 
 /// Intern `ret`. This function assumes that `ret` references no other allocation.
diff --git a/compiler/rustc_const_eval/src/interpret/memory.rs b/compiler/rustc_const_eval/src/interpret/memory.rs
index 23b40894f16..2c1e5087e1c 100644
--- a/compiler/rustc_const_eval/src/interpret/memory.rs
+++ b/compiler/rustc_const_eval/src/interpret/memory.rs
@@ -1314,29 +1314,20 @@ impl<'a, 'tcx, Prov: Provenance, Extra, Bytes: AllocBytes>
     }
 
     /// Mark the given sub-range (relative to this allocation reference) as uninitialized.
-    pub fn write_uninit(&mut self, range: AllocRange) -> InterpResult<'tcx> {
+    pub fn write_uninit(&mut self, range: AllocRange) {
         let range = self.range.subrange(range);
 
-        self.alloc
-            .write_uninit(&self.tcx, range)
-            .map_err(|e| e.to_interp_error(self.alloc_id))
-            .into()
+        self.alloc.write_uninit(&self.tcx, range);
     }
 
     /// Mark the entire referenced range as uninitialized
-    pub fn write_uninit_full(&mut self) -> InterpResult<'tcx> {
-        self.alloc
-            .write_uninit(&self.tcx, self.range)
-            .map_err(|e| e.to_interp_error(self.alloc_id))
-            .into()
+    pub fn write_uninit_full(&mut self) {
+        self.alloc.write_uninit(&self.tcx, self.range);
     }
 
     /// Remove all provenance in the reference range.
-    pub fn clear_provenance(&mut self) -> InterpResult<'tcx> {
-        self.alloc
-            .clear_provenance(&self.tcx, self.range)
-            .map_err(|e| e.to_interp_error(self.alloc_id))
-            .into()
+    pub fn clear_provenance(&mut self) {
+        self.alloc.clear_provenance(&self.tcx, self.range);
     }
 }
 
@@ -1427,11 +1418,8 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
 
         // Side-step AllocRef and directly access the underlying bytes more efficiently.
         // (We are staying inside the bounds here and all bytes do get overwritten so all is good.)
-        let alloc_id = alloc_ref.alloc_id;
-        let bytes = alloc_ref
-            .alloc
-            .get_bytes_unchecked_for_overwrite(&alloc_ref.tcx, alloc_ref.range)
-            .map_err(move |e| e.to_interp_error(alloc_id))?;
+        let bytes =
+            alloc_ref.alloc.get_bytes_unchecked_for_overwrite(&alloc_ref.tcx, alloc_ref.range);
         // `zip` would stop when the first iterator ends; we want to definitely
         // cover all of `bytes`.
         for dest in bytes {
@@ -1513,10 +1501,8 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         // `get_bytes_mut` will clear the provenance, which is correct,
         // since we don't want to keep any provenance at the target.
         // This will also error if copying partial provenance is not supported.
-        let provenance = src_alloc
-            .provenance()
-            .prepare_copy(src_range, dest_offset, num_copies, self)
-            .map_err(|e| e.to_interp_error(src_alloc_id))?;
+        let provenance =
+            src_alloc.provenance().prepare_copy(src_range, dest_offset, num_copies, self);
         // Prepare a copy of the initialization mask.
         let init = src_alloc.init_mask().prepare_copy(src_range);
 
@@ -1534,10 +1520,8 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
             dest_range,
         )?;
         // Yes we do overwrite all bytes in `dest_bytes`.
-        let dest_bytes = dest_alloc
-            .get_bytes_unchecked_for_overwrite_ptr(&tcx, dest_range)
-            .map_err(|e| e.to_interp_error(dest_alloc_id))?
-            .as_mut_ptr();
+        let dest_bytes =
+            dest_alloc.get_bytes_unchecked_for_overwrite_ptr(&tcx, dest_range).as_mut_ptr();
 
         if init.no_bytes_init() {
             // Fast path: If all bytes are `uninit` then there is nothing to copy. The target range
@@ -1546,9 +1530,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
             // This also avoids writing to the target bytes so that the backing allocation is never
             // touched if the bytes stay uninitialized for the whole interpreter execution. On contemporary
             // operating system this can avoid physically allocating the page.
-            dest_alloc
-                .write_uninit(&tcx, dest_range)
-                .map_err(|e| e.to_interp_error(dest_alloc_id))?;
+            dest_alloc.write_uninit(&tcx, dest_range);
             // `write_uninit` also resets the provenance, so we are done.
             return interp_ok(());
         }
diff --git a/compiler/rustc_const_eval/src/interpret/operand.rs b/compiler/rustc_const_eval/src/interpret/operand.rs
index 53a440b646b..560b0e1ae4e 100644
--- a/compiler/rustc_const_eval/src/interpret/operand.rs
+++ b/compiler/rustc_const_eval/src/interpret/operand.rs
@@ -175,6 +175,16 @@ impl<Prov: Provenance> Immediate<Prov> {
         }
         interp_ok(())
     }
+
+    pub fn has_provenance(&self) -> bool {
+        match self {
+            Immediate::Scalar(scalar) => matches!(scalar, Scalar::Ptr { .. }),
+            Immediate::ScalarPair(s1, s2) => {
+                matches!(s1, Scalar::Ptr { .. }) || matches!(s2, Scalar::Ptr { .. })
+            }
+            Immediate::Uninit => false,
+        }
+    }
 }
 
 // ScalarPair needs a type to interpret, so we often have an immediate and a type together
diff --git a/compiler/rustc_const_eval/src/interpret/place.rs b/compiler/rustc_const_eval/src/interpret/place.rs
index 6ff50dc700f..a86fdf80f60 100644
--- a/compiler/rustc_const_eval/src/interpret/place.rs
+++ b/compiler/rustc_const_eval/src/interpret/place.rs
@@ -234,6 +234,12 @@ impl<'tcx, Prov: Provenance> PlaceTy<'tcx, Prov> {
     }
 
     /// A place is either an mplace or some local.
+    ///
+    /// Note that the return value can be different even for logically identical places!
+    /// Specifically, if a local is stored in-memory, this may return `Local` or `MPlaceTy`
+    /// depending on how the place was constructed. In other words, seeing `Local` here does *not*
+    /// imply that this place does not point to memory. Every caller must therefore always handle
+    /// both cases.
     #[inline(always)]
     pub fn as_mplace_or_local(
         &self,
@@ -705,7 +711,7 @@ where
 
         match value {
             Immediate::Scalar(scalar) => {
-                alloc.write_scalar(alloc_range(Size::ZERO, scalar.size()), scalar)
+                alloc.write_scalar(alloc_range(Size::ZERO, scalar.size()), scalar)?;
             }
             Immediate::ScalarPair(a_val, b_val) => {
                 let BackendRepr::ScalarPair(a, b) = layout.backend_repr else {
@@ -725,10 +731,10 @@ where
                 alloc.write_scalar(alloc_range(Size::ZERO, a_val.size()), a_val)?;
                 alloc.write_scalar(alloc_range(b_offset, b_val.size()), b_val)?;
                 // We don't have to reset padding here, `write_immediate` will anyway do a validation run.
-                interp_ok(())
             }
             Immediate::Uninit => alloc.write_uninit_full(),
         }
+        interp_ok(())
     }
 
     pub fn write_uninit(
@@ -748,7 +754,7 @@ where
                     // Zero-sized access
                     return interp_ok(());
                 };
-                alloc.write_uninit_full()?;
+                alloc.write_uninit_full();
             }
         }
         interp_ok(())
@@ -759,6 +765,13 @@ where
         &mut self,
         dest: &impl Writeable<'tcx, M::Provenance>,
     ) -> InterpResult<'tcx> {
+        // If this is an efficiently represented local variable without provenance, skip the
+        // `as_mplace_or_mutable_local` that would otherwise force this local into memory.
+        if let Right(imm) = dest.to_op(self)?.as_mplace_or_imm() {
+            if !imm.has_provenance() {
+                return interp_ok(());
+            }
+        }
         match self.as_mplace_or_mutable_local(&dest.to_place())? {
             Right((local_val, _local_layout, local)) => {
                 local_val.clear_provenance()?;
@@ -772,7 +785,7 @@ where
                     // Zero-sized access
                     return interp_ok(());
                 };
-                alloc.clear_provenance()?;
+                alloc.clear_provenance();
             }
         }
         interp_ok(())
diff --git a/compiler/rustc_const_eval/src/interpret/stack.rs b/compiler/rustc_const_eval/src/interpret/stack.rs
index 73cc87508ef..7cabfd96121 100644
--- a/compiler/rustc_const_eval/src/interpret/stack.rs
+++ b/compiler/rustc_const_eval/src/interpret/stack.rs
@@ -20,7 +20,7 @@ use super::{
     MemoryKind, Operand, PlaceTy, Pointer, Provenance, ReturnAction, Scalar, from_known_layout,
     interp_ok, throw_ub, throw_unsup,
 };
-use crate::errors;
+use crate::{enter_trace_span, errors};
 
 // The Phantomdata exists to prevent this type from being `Send`. If it were sent across a thread
 // boundary and dropped in the other thread, it would exit the span in the other thread.
@@ -386,6 +386,9 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
 
         // Make sure all the constants required by this frame evaluate successfully (post-monomorphization check).
         for &const_ in body.required_consts() {
+            // We can't use `eval_mir_constant` here as that assumes that all required consts have
+            // already been checked, so we need a separate tracing call.
+            let _trace = enter_trace_span!(M, const_eval::required_consts, ?const_.const_);
             let c =
                 self.instantiate_from_current_frame_and_normalize_erasing_regions(const_.const_)?;
             c.eval(*self.tcx, self.typing_env, const_.span).map_err(|err| {
diff --git a/compiler/rustc_const_eval/src/interpret/step.rs b/compiler/rustc_const_eval/src/interpret/step.rs
index 76e470b69dc..23d362de308 100644
--- a/compiler/rustc_const_eval/src/interpret/step.rs
+++ b/compiler/rustc_const_eval/src/interpret/step.rs
@@ -2,8 +2,11 @@
 //!
 //! The main entry point is the `step` method.
 
+use std::iter;
+
 use either::Either;
 use rustc_abi::{FIRST_VARIANT, FieldIdx};
+use rustc_data_structures::fx::FxHashSet;
 use rustc_index::IndexSlice;
 use rustc_middle::ty::{self, Instance, Ty};
 use rustc_middle::{bug, mir, span_bug};
@@ -389,8 +392,9 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
 
     /// Evaluate the arguments of a function call
     fn eval_fn_call_argument(
-        &self,
+        &mut self,
         op: &mir::Operand<'tcx>,
+        move_definitely_disjoint: bool,
     ) -> InterpResult<'tcx, FnArg<'tcx, M::Provenance>> {
         interp_ok(match op {
             mir::Operand::Copy(_) | mir::Operand::Constant(_) => {
@@ -399,24 +403,19 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 FnArg::Copy(op)
             }
             mir::Operand::Move(place) => {
-                // If this place lives in memory, preserve its location.
-                // We call `place_to_op` which will be an `MPlaceTy` whenever there exists
-                // an mplace for this place. (This is in contrast to `PlaceTy::as_mplace_or_local`
-                // which can return a local even if that has an mplace.)
                 let place = self.eval_place(*place)?;
-                let op = self.place_to_op(&place)?;
-
-                match op.as_mplace_or_imm() {
-                    Either::Left(mplace) => FnArg::InPlace(mplace),
-                    Either::Right(_imm) => {
-                        // This argument doesn't live in memory, so there's no place
-                        // to make inaccessible during the call.
-                        // We rely on there not being any stray `PlaceTy` that would let the
-                        // caller directly access this local!
-                        // This is also crucial for tail calls, where we want the `FnArg` to
-                        // stay valid when the old stack frame gets popped.
-                        FnArg::Copy(op)
+                if move_definitely_disjoint {
+                    // We still have to ensure that no *other* pointers are used to access this place,
+                    // so *if* it is in memory then we have to treat it as `InPlace`.
+                    // Use `place_to_op` to guarantee that we notice it being in memory.
+                    let op = self.place_to_op(&place)?;
+                    match op.as_mplace_or_imm() {
+                        Either::Left(mplace) => FnArg::InPlace(mplace),
+                        Either::Right(_imm) => FnArg::Copy(op),
                     }
+                } else {
+                    // We have to force this into memory to detect aliasing among `Move` arguments.
+                    FnArg::InPlace(self.force_allocation(&place)?)
                 }
             }
         })
@@ -425,18 +424,53 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
     /// Shared part of `Call` and `TailCall` implementation — finding and evaluating all the
     /// necessary information about callee and arguments to make a call.
     fn eval_callee_and_args(
-        &self,
+        &mut self,
         terminator: &mir::Terminator<'tcx>,
         func: &mir::Operand<'tcx>,
         args: &[Spanned<mir::Operand<'tcx>>],
+        dest: &mir::Place<'tcx>,
     ) -> InterpResult<'tcx, EvaluatedCalleeAndArgs<'tcx, M>> {
         let func = self.eval_operand(func, None)?;
+
+        // Evaluating function call arguments. The tricky part here is dealing with `Move`
+        // arguments: we have to ensure no two such arguments alias. This would be most easily done
+        // by just forcing them all into memory and then doing the usual in-place argument
+        // protection, but then we'd force *a lot* of arguments into memory. So we do some syntactic
+        // pre-processing here where if all `move` arguments are syntactically distinct local
+        // variables (and none is indirect), we can skip the in-memory forcing.
+        // We have to include `dest` in that list so that we can detect aliasing of an in-place
+        // argument with the return place.
+        let move_definitely_disjoint = 'move_definitely_disjoint: {
+            let mut previous_locals = FxHashSet::<mir::Local>::default();
+            for place in args
+                .iter()
+                .filter_map(|a| {
+                    // We only have to care about `Move` arguments.
+                    if let mir::Operand::Move(place) = &a.node { Some(place) } else { None }
+                })
+                .chain(iter::once(dest))
+            {
+                if place.is_indirect_first_projection() {
+                    // An indirect in-place argument could alias with anything else...
+                    break 'move_definitely_disjoint false;
+                }
+                if !previous_locals.insert(place.local) {
+                    // This local is the base for two arguments! They might overlap.
+                    break 'move_definitely_disjoint false;
+                }
+            }
+            // We found no violation so they are all definitely disjoint.
+            true
+        };
         let args = args
             .iter()
-            .map(|arg| self.eval_fn_call_argument(&arg.node))
+            .map(|arg| self.eval_fn_call_argument(&arg.node, move_definitely_disjoint))
             .collect::<InterpResult<'tcx, Vec<_>>>()?;
 
-        let fn_sig_binder = func.layout.ty.fn_sig(*self.tcx);
+        let fn_sig_binder = {
+            let _trace = enter_trace_span!(M, "fn_sig", ty = ?func.layout.ty.kind());
+            func.layout.ty.fn_sig(*self.tcx)
+        };
         let fn_sig = self.tcx.normalize_erasing_late_bound_regions(self.typing_env, fn_sig_binder);
         let extra_args = &args[fn_sig.inputs().len()..];
         let extra_args =
@@ -519,7 +553,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 let old_loc = self.frame().loc;
 
                 let EvaluatedCalleeAndArgs { callee, args, fn_sig, fn_abi, with_caller_location } =
-                    self.eval_callee_and_args(terminator, func, args)?;
+                    self.eval_callee_and_args(terminator, func, args, &destination)?;
 
                 let destination = self.eval_place(destination)?;
                 self.init_fn_call(
@@ -542,7 +576,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 let old_frame_idx = self.frame_idx();
 
                 let EvaluatedCalleeAndArgs { callee, args, fn_sig, fn_abi, with_caller_location } =
-                    self.eval_callee_and_args(terminator, func, args)?;
+                    self.eval_callee_and_args(terminator, func, args, &mir::Place::return_place())?;
 
                 self.init_fn_tail_call(callee, (fn_sig.abi, fn_abi), &args, with_caller_location)?;
 
@@ -560,7 +594,11 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                     "Async Drop must be expanded or reset to sync in runtime MIR"
                 );
                 let place = self.eval_place(place)?;
-                let instance = Instance::resolve_drop_in_place(*self.tcx, place.layout.ty);
+                let instance = {
+                    let _trace =
+                        enter_trace_span!(M, resolve::resolve_drop_in_place, ty = ?place.layout.ty);
+                    Instance::resolve_drop_in_place(*self.tcx, place.layout.ty)
+                };
                 if let ty::InstanceKind::DropGlue(_, None) = instance.def {
                     // This is the branch we enter if and only if the dropped type has no drop glue
                     // whatsoever. This can happen as a result of monomorphizing a drop of a
diff --git a/compiler/rustc_const_eval/src/interpret/validity.rs b/compiler/rustc_const_eval/src/interpret/validity.rs
index ab0c0665d51..02e3d90f4af 100644
--- a/compiler/rustc_const_eval/src/interpret/validity.rs
+++ b/compiler/rustc_const_eval/src/interpret/validity.rs
@@ -949,7 +949,7 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValidityVisitor<'rt, 'tcx, M> {
                 let padding_size = offset - padding_cleared_until;
                 let range = alloc_range(padding_start, padding_size);
                 trace!("reset_padding on {}: resetting padding range {range:?}", mplace.layout.ty);
-                alloc.write_uninit(range)?;
+                alloc.write_uninit(range);
             }
             padding_cleared_until = offset + size;
         }
@@ -1239,7 +1239,7 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValueVisitor<'tcx, M> for ValidityVisitor<'rt,
                 if self.reset_provenance_and_padding {
                     // We can't share this with above as above, we might be looking at read-only memory.
                     let mut alloc = self.ecx.get_ptr_alloc_mut(mplace.ptr(), size)?.expect("we already excluded size 0");
-                    alloc.clear_provenance()?;
+                    alloc.clear_provenance();
                     // Also, mark this as containing data, not padding.
                     self.add_data_range(mplace.ptr(), size);
                 }
@@ -1418,7 +1418,9 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
         let _trace = enter_trace_span!(
             M,
             "validate_operand",
-            "recursive={recursive}, reset_provenance_and_padding={reset_provenance_and_padding}, val={val:?}"
+            recursive,
+            reset_provenance_and_padding,
+            ?val,
         );
 
         // Note that we *could* actually be in CTFE here with `-Zextra-const-ub-checks`, but it's
diff --git a/compiler/rustc_const_eval/src/util/type_name.rs b/compiler/rustc_const_eval/src/util/type_name.rs
index 2dc746754f8..2ae6655901b 100644
--- a/compiler/rustc_const_eval/src/util/type_name.rs
+++ b/compiler/rustc_const_eval/src/util/type_name.rs
@@ -1,26 +1,27 @@
 use std::fmt::Write;
 
 use rustc_data_structures::intern::Interned;
-use rustc_hir::def_id::CrateNum;
+use rustc_hir::def_id::{CrateNum, DefId};
 use rustc_hir::definitions::DisambiguatedDefPathData;
 use rustc_middle::bug;
 use rustc_middle::ty::print::{PrettyPrinter, PrintError, Printer};
-use rustc_middle::ty::{self, GenericArg, GenericArgKind, Ty, TyCtxt};
+use rustc_middle::ty::{self, GenericArg, Ty, TyCtxt};
 
-struct AbsolutePathPrinter<'tcx> {
+struct TypeNamePrinter<'tcx> {
     tcx: TyCtxt<'tcx>,
     path: String,
 }
 
-impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
+impl<'tcx> Printer<'tcx> for TypeNamePrinter<'tcx> {
     fn tcx(&self) -> TyCtxt<'tcx> {
         self.tcx
     }
 
     fn print_region(&mut self, _region: ty::Region<'_>) -> Result<(), PrintError> {
-        // This is reachable (via `pretty_print_dyn_existential`) even though
-        // `<Self As PrettyPrinter>::should_print_region` returns false. See #144994.
-        Ok(())
+        // FIXME: most regions have been erased by the time this code runs.
+        // Just printing `'_` is a bit hacky but gives mostly good results, and
+        // doing better is difficult. See `should_print_optional_region`.
+        write!(self, "'_")
     }
 
     fn print_type(&mut self, ty: Ty<'tcx>) -> Result<(), PrintError> {
@@ -75,26 +76,26 @@ impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
         self.pretty_print_dyn_existential(predicates)
     }
 
-    fn path_crate(&mut self, cnum: CrateNum) -> Result<(), PrintError> {
+    fn print_crate_name(&mut self, cnum: CrateNum) -> Result<(), PrintError> {
         self.path.push_str(self.tcx.crate_name(cnum).as_str());
         Ok(())
     }
 
-    fn path_qualified(
+    fn print_path_with_qualified(
         &mut self,
         self_ty: Ty<'tcx>,
         trait_ref: Option<ty::TraitRef<'tcx>>,
     ) -> Result<(), PrintError> {
-        self.pretty_path_qualified(self_ty, trait_ref)
+        self.pretty_print_path_with_qualified(self_ty, trait_ref)
     }
 
-    fn path_append_impl(
+    fn print_path_with_impl(
         &mut self,
         print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
         self_ty: Ty<'tcx>,
         trait_ref: Option<ty::TraitRef<'tcx>>,
     ) -> Result<(), PrintError> {
-        self.pretty_path_append_impl(
+        self.pretty_print_path_with_impl(
             |cx| {
                 print_prefix(cx)?;
 
@@ -107,7 +108,7 @@ impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
         )
     }
 
-    fn path_append(
+    fn print_path_with_simple(
         &mut self,
         print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
         disambiguated_data: &DisambiguatedDefPathData,
@@ -119,25 +120,59 @@ impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
         Ok(())
     }
 
-    fn path_generic_args(
+    fn print_path_with_generic_args(
         &mut self,
         print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
         args: &[GenericArg<'tcx>],
     ) -> Result<(), PrintError> {
         print_prefix(self)?;
-        let args =
-            args.iter().cloned().filter(|arg| !matches!(arg.kind(), GenericArgKind::Lifetime(_)));
-        if args.clone().next().is_some() {
-            self.generic_delimiters(|cx| cx.comma_sep(args))
+        if !args.is_empty() {
+            self.generic_delimiters(|cx| cx.comma_sep(args.iter().copied()))
         } else {
             Ok(())
         }
     }
+
+    fn print_coroutine_with_kind(
+        &mut self,
+        def_id: DefId,
+        parent_args: &'tcx [GenericArg<'tcx>],
+        kind: Ty<'tcx>,
+    ) -> Result<(), PrintError> {
+        self.print_def_path(def_id, parent_args)?;
+
+        let ty::Coroutine(_, args) = self.tcx.type_of(def_id).instantiate_identity().kind() else {
+            // Could be `ty::Error`.
+            return Ok(());
+        };
+
+        let default_kind = args.as_coroutine().kind_ty();
+
+        match kind.to_opt_closure_kind() {
+            _ if kind == default_kind => {
+                // No need to mark the closure if it's the deduced coroutine kind.
+            }
+            Some(ty::ClosureKind::Fn) | None => {
+                // Should never happen. Just don't mark anything rather than panicking.
+            }
+            Some(ty::ClosureKind::FnMut) => self.path.push_str("::{{call_mut}}"),
+            Some(ty::ClosureKind::FnOnce) => self.path.push_str("::{{call_once}}"),
+        }
+
+        Ok(())
+    }
 }
 
-impl<'tcx> PrettyPrinter<'tcx> for AbsolutePathPrinter<'tcx> {
-    fn should_print_region(&self, _region: ty::Region<'_>) -> bool {
-        false
+impl<'tcx> PrettyPrinter<'tcx> for TypeNamePrinter<'tcx> {
+    fn should_print_optional_region(&self, region: ty::Region<'_>) -> bool {
+        // Bound regions are always printed (as `'_`), which gives some idea that they are special,
+        // even though the `for` is omitted by the pretty printer.
+        // E.g. `for<'a, 'b> fn(&'a u32, &'b u32)` is printed as "fn(&'_ u32, &'_ u32)".
+        match region.kind() {
+            ty::ReErased | ty::ReEarlyParam(_) => false,
+            ty::ReBound(..) => true,
+            _ => unreachable!(),
+        }
     }
 
     fn generic_delimiters(
@@ -159,7 +194,7 @@ impl<'tcx> PrettyPrinter<'tcx> for AbsolutePathPrinter<'tcx> {
     }
 }
 
-impl Write for AbsolutePathPrinter<'_> {
+impl Write for TypeNamePrinter<'_> {
     fn write_str(&mut self, s: &str) -> std::fmt::Result {
         self.path.push_str(s);
         Ok(())
@@ -167,7 +202,7 @@ impl Write for AbsolutePathPrinter<'_> {
 }
 
 pub fn type_name<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> String {
-    let mut p = AbsolutePathPrinter { tcx, path: String::new() };
+    let mut p = TypeNamePrinter { tcx, path: String::new() };
     p.print_type(ty).unwrap();
     p.path
 }
diff --git a/compiler/rustc_data_structures/Cargo.toml b/compiler/rustc_data_structures/Cargo.toml
index 17204883fb0..0ac9e02508a 100644
--- a/compiler/rustc_data_structures/Cargo.toml
+++ b/compiler/rustc_data_structures/Cargo.toml
@@ -6,13 +6,14 @@ edition = "2024"
 [dependencies]
 # tidy-alphabetical-start
 arrayvec = { version = "0.7", default-features = false }
-bitflags = "2.4.1"
+bitflags.workspace = true
 either = "1.0"
 elsa = "1.11.0"
 ena = "0.14.3"
 indexmap = "2.4.0"
 jobserver_crate = { version = "0.1.28", package = "jobserver" }
 measureme = "12.0.1"
+parking_lot = "0.12"
 rustc-hash = "2.0.0"
 rustc-stable-hash = { version = "0.1.0", features = ["nightly"] }
 rustc_arena = { path = "../rustc_arena" }
@@ -25,8 +26,8 @@ rustc_thread_pool = { path = "../rustc_thread_pool" }
 smallvec = { version = "1.8.1", features = ["const_generics", "union", "may_dangle"] }
 stacker = "0.1.17"
 tempfile = "3.2"
-thin-vec = "0.2.12"
-tracing = "0.1"
+thin-vec.workspace = true
+tracing.workspace = true
 # tidy-alphabetical-end
 
 [dependencies.hashbrown]
@@ -34,9 +35,6 @@ version = "0.15.2"
 default-features = false
 features = ["nightly"] # for may_dangle
 
-[dependencies.parking_lot]
-version = "0.12"
-
 [target.'cfg(windows)'.dependencies.windows]
 version = "0.61.0"
 features = [
diff --git a/compiler/rustc_data_structures/src/lib.rs b/compiler/rustc_data_structures/src/lib.rs
index 53178d09348..17da3ea83c8 100644
--- a/compiler/rustc_data_structures/src/lib.rs
+++ b/compiler/rustc_data_structures/src/lib.rs
@@ -77,6 +77,7 @@ pub mod thinvec;
 pub mod thousands;
 pub mod transitive_relation;
 pub mod unhash;
+pub mod union_find;
 pub mod unord;
 pub mod vec_cache;
 pub mod work_queue;
diff --git a/compiler/rustc_mir_transform/src/coverage/counters/union_find.rs b/compiler/rustc_data_structures/src/union_find.rs
index a826a953fa6..ef73cd7ab40 100644
--- a/compiler/rustc_mir_transform/src/coverage/counters/union_find.rs
+++ b/compiler/rustc_data_structures/src/union_find.rs
@@ -9,7 +9,7 @@ mod tests;
 /// Simple implementation of a union-find data structure, i.e. a disjoint-set
 /// forest.
 #[derive(Debug)]
-pub(crate) struct UnionFind<Key: Idx> {
+pub struct UnionFind<Key: Idx> {
     table: IndexVec<Key, UnionFindEntry<Key>>,
 }
 
@@ -28,7 +28,7 @@ struct UnionFindEntry<Key> {
 impl<Key: Idx> UnionFind<Key> {
     /// Creates a new disjoint-set forest containing the keys `0..num_keys`.
     /// Initially, every key is part of its own one-element set.
-    pub(crate) fn new(num_keys: usize) -> Self {
+    pub fn new(num_keys: usize) -> Self {
         // Initially, every key is the root of its own set, so its parent is itself.
         Self { table: IndexVec::from_fn_n(|key| UnionFindEntry { parent: key, rank: 0 }, num_keys) }
     }
@@ -38,7 +38,7 @@ impl<Key: Idx> UnionFind<Key> {
     ///
     /// Also updates internal data structures to make subsequent `find`
     /// operations faster.
-    pub(crate) fn find(&mut self, key: Key) -> Key {
+    pub fn find(&mut self, key: Key) -> Key {
         // Loop until we find a key that is its own parent.
         let mut curr = key;
         while let parent = self.table[curr].parent
@@ -60,7 +60,7 @@ impl<Key: Idx> UnionFind<Key> {
     /// Merges the set containing `a` and the set containing `b` into one set.
     ///
     /// Returns the common root of both keys, after the merge.
-    pub(crate) fn unify(&mut self, a: Key, b: Key) -> Key {
+    pub fn unify(&mut self, a: Key, b: Key) -> Key {
         let mut a = self.find(a);
         let mut b = self.find(b);
 
@@ -90,7 +90,7 @@ impl<Key: Idx> UnionFind<Key> {
 
     /// Takes a "snapshot" of the current state of this disjoint-set forest, in
     /// the form of a vector that directly maps each key to its current root.
-    pub(crate) fn snapshot(&mut self) -> IndexVec<Key, Key> {
+    pub fn snapshot(&mut self) -> IndexVec<Key, Key> {
         self.table.indices().map(|key| self.find(key)).collect()
     }
 }
diff --git a/compiler/rustc_mir_transform/src/coverage/counters/union_find/tests.rs b/compiler/rustc_data_structures/src/union_find/tests.rs
index 34a4e4f8e6e..34a4e4f8e6e 100644
--- a/compiler/rustc_mir_transform/src/coverage/counters/union_find/tests.rs
+++ b/compiler/rustc_data_structures/src/union_find/tests.rs
diff --git a/compiler/rustc_driver_impl/Cargo.toml b/compiler/rustc_driver_impl/Cargo.toml
index ae1dbd2cf51..7e9af054aff 100644
--- a/compiler/rustc_driver_impl/Cargo.toml
+++ b/compiler/rustc_driver_impl/Cargo.toml
@@ -51,7 +51,7 @@ rustc_trait_selection = { path = "../rustc_trait_selection" }
 rustc_ty_utils = { path = "../rustc_ty_utils" }
 serde_json = "1.0.59"
 shlex = "1.0"
-tracing = { version = "0.1.35" }
+tracing.workspace = true
 # tidy-alphabetical-end
 
 [target.'cfg(all(unix, any(target_env = "gnu", target_os = "macos")))'.dependencies]
diff --git a/compiler/rustc_error_codes/src/error_codes/E0458.md b/compiler/rustc_error_codes/src/error_codes/E0458.md
index 1b280cba44f..651bc378879 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0458.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0458.md
@@ -1,8 +1,10 @@
+#### Note: this error code is no longer emitted by the compiler.
+
 An unknown "kind" was specified for a link attribute.
 
 Erroneous code example:
 
-```compile_fail,E0458
+```ignore (no longer emitted)
 #[link(kind = "wonderful_unicorn")] extern "C" {}
 // error: unknown kind: `wonderful_unicorn`
 ```
diff --git a/compiler/rustc_error_codes/src/error_codes/E0518.md b/compiler/rustc_error_codes/src/error_codes/E0518.md
index f04329bc4e6..87dc231578a 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0518.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0518.md
@@ -1,9 +1,11 @@
+#### Note: this error code is no longer emitted by the compiler.
+
 An `#[inline(..)]` attribute was incorrectly placed on something other than a
 function or method.
 
 Example of erroneous code:
 
-```compile_fail,E0518
+```ignore (no longer emitted)
 #[inline(always)]
 struct Foo;
 
diff --git a/compiler/rustc_error_codes/src/error_codes/E0578.md b/compiler/rustc_error_codes/src/error_codes/E0578.md
index fca89757287..78fabe855bb 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0578.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0578.md
@@ -1,8 +1,10 @@
+#### Note: this error code is no longer emitted by the compiler.
+
 A module cannot be found and therefore, the visibility cannot be determined.
 
 Erroneous code example:
 
-```compile_fail,E0578,edition2018
+```ignore (no longer emitted)
 foo!();
 
 pub (in ::Sea) struct Shark; // error!
diff --git a/compiler/rustc_error_codes/src/error_codes/E0701.md b/compiler/rustc_error_codes/src/error_codes/E0701.md
index 4965e643105..e1be0e915f4 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0701.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0701.md
@@ -1,9 +1,11 @@
+#### Note: this error code is no longer emitted by the compiler.
+
 This error indicates that a `#[non_exhaustive]` attribute was incorrectly placed
 on something other than a struct or enum.
 
 Erroneous code example:
 
-```compile_fail,E0701
+```ignore (no longer emitted)
 #[non_exhaustive]
 trait Foo { }
 ```
diff --git a/compiler/rustc_error_codes/src/error_codes/E0739.md b/compiler/rustc_error_codes/src/error_codes/E0739.md
index 406d3d52779..5403405ca9d 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0739.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0739.md
@@ -1,8 +1,10 @@
+#### Note: this error code is no longer emitted by the compiler.
+
 `#[track_caller]` must  be applied to a function
 
 Erroneous code example:
 
-```compile_fail,E0739
+```ignore (no longer emitted)
 #[track_caller]
 struct Bar {
     a: u8,
diff --git a/compiler/rustc_error_codes/src/error_codes/E0755.md b/compiler/rustc_error_codes/src/error_codes/E0755.md
index b67f078c78e..bd93626a8db 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0755.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0755.md
@@ -1,8 +1,10 @@
+#### Note: this error code is no longer emitted by the compiler.
+
 The `ffi_pure` attribute was used on a non-foreign function.
 
 Erroneous code example:
 
-```compile_fail,E0755
+```ignore (no longer emitted)
 #![feature(ffi_pure)]
 
 #[unsafe(ffi_pure)] // error!
diff --git a/compiler/rustc_error_codes/src/error_codes/E0756.md b/compiler/rustc_error_codes/src/error_codes/E0756.md
index aadde038d12..daafc2a5ac0 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0756.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0756.md
@@ -1,9 +1,11 @@
+#### Note: this error code is no longer emitted by the compiler.
+
 The `ffi_const` attribute was used on something other than a foreign function
 declaration.
 
 Erroneous code example:
 
-```compile_fail,E0756
+```ignore (no longer emitted)
 #![feature(ffi_const)]
 
 #[unsafe(ffi_const)] // error!
diff --git a/compiler/rustc_error_codes/src/error_codes/E0788.md b/compiler/rustc_error_codes/src/error_codes/E0788.md
index ba138aed2d1..1afa961f9b7 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0788.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0788.md
@@ -1,3 +1,5 @@
+#### Note: this error code is no longer emitted by the compiler.
+
 A `#[coverage(off|on)]` attribute was found in a position where it is not
 allowed.
 
@@ -10,7 +12,7 @@ Coverage attributes can be applied to:
 
 Example of erroneous code:
 
-```compile_fail,E0788
+```ignore (no longer emitted)
 unsafe extern "C" {
     #[coverage(off)]
     fn foreign_fn();
diff --git a/compiler/rustc_error_codes/src/error_codes/E0793.md b/compiler/rustc_error_codes/src/error_codes/E0793.md
index ccd1b43bd19..2722dac104b 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0793.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0793.md
@@ -1,4 +1,9 @@
-An unaligned reference to a field of a [packed] struct got created.
+An unaligned reference to a field of a [packed] `struct` or `union` was created.
+
+The `#[repr(packed)]` attribute removes padding between fields, which can
+cause fields to be stored at unaligned memory addresses. Creating references
+to such fields violates Rust's memory safety guarantees and can lead to
+undefined behavior in optimized code.
 
 Erroneous code example:
 
@@ -45,9 +50,36 @@ unsafe {
     // For formatting, we can create a copy to avoid the direct reference.
     let copy = foo.field1;
     println!("{}", copy);
+
     // Creating a copy can be written in a single line with curly braces.
     // (This is equivalent to the two lines above.)
     println!("{}", { foo.field1 });
+
+    // A reference to a field that will always be sufficiently aligned is safe:
+    println!("{}", foo.field2);
+}
+```
+
+### Unions
+
+Although creating a reference to a `union` field is `unsafe`, this error
+will still be triggered if the referenced field is not sufficiently
+aligned. Use `addr_of!` and raw pointers in the same way as for struct fields.
+
+```compile_fail,E0793
+#[repr(packed)]
+pub union Foo {
+    field1: u64,
+    field2: u8,
+}
+
+unsafe {
+    let foo = Foo { field1: 0 };
+    // Accessing the field directly is fine.
+    let val = foo.field1;
+
+    // A reference to a packed union field causes an error.
+    let val = &foo.field1; // ERROR
 }
 ```
 
diff --git a/compiler/rustc_error_messages/Cargo.toml b/compiler/rustc_error_messages/Cargo.toml
index 0951859fa53..7d2dc20e136 100644
--- a/compiler/rustc_error_messages/Cargo.toml
+++ b/compiler/rustc_error_messages/Cargo.toml
@@ -7,15 +7,16 @@ edition = "2024"
 # tidy-alphabetical-start
 fluent-bundle = "0.16"
 fluent-syntax = "0.12"
-icu_list = "1.2"
-icu_locid = "1.2"
-icu_provider_adapters = "1.2"
+icu_list = { version = "2.0", default-features = false, features = ["alloc"] }
+icu_locale = { version = "2.0", default-features = false }
 intl-memoizer = "0.5.1"
+rustc_ast = { path = "../rustc_ast" }
+rustc_ast_pretty = { path = "../rustc_ast_pretty" }
 rustc_baked_icu_data = { path = "../rustc_baked_icu_data" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_span = { path = "../rustc_span" }
-tracing = "0.1"
+tracing.workspace = true
 unic-langid = { version = "0.9.0", features = ["macros"] }
 # tidy-alphabetical-end
diff --git a/compiler/rustc_error_messages/src/diagnostic_impls.rs b/compiler/rustc_error_messages/src/diagnostic_impls.rs
new file mode 100644
index 00000000000..3b664cce577
--- /dev/null
+++ b/compiler/rustc_error_messages/src/diagnostic_impls.rs
@@ -0,0 +1,205 @@
+use std::backtrace::Backtrace;
+use std::borrow::Cow;
+use std::fmt;
+use std::num::ParseIntError;
+use std::path::{Path, PathBuf};
+use std::process::ExitStatus;
+
+use rustc_ast as ast;
+use rustc_ast_pretty::pprust;
+use rustc_span::edition::Edition;
+
+use crate::{DiagArgValue, IntoDiagArg};
+
+pub struct DiagArgFromDisplay<'a>(pub &'a dyn fmt::Display);
+
+impl IntoDiagArg for DiagArgFromDisplay<'_> {
+    fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        self.0.to_string().into_diag_arg(path)
+    }
+}
+
+impl<'a> From<&'a dyn fmt::Display> for DiagArgFromDisplay<'a> {
+    fn from(t: &'a dyn fmt::Display) -> Self {
+        DiagArgFromDisplay(t)
+    }
+}
+
+impl<'a, T: fmt::Display> From<&'a T> for DiagArgFromDisplay<'a> {
+    fn from(t: &'a T) -> Self {
+        DiagArgFromDisplay(t)
+    }
+}
+
+impl<'a, T: Clone + IntoDiagArg> IntoDiagArg for &'a T {
+    fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        self.clone().into_diag_arg(path)
+    }
+}
+
+#[macro_export]
+macro_rules! into_diag_arg_using_display {
+    ($( $ty:ty ),+ $(,)?) => {
+        $(
+            impl $crate::IntoDiagArg for $ty {
+                fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> $crate::DiagArgValue {
+                    self.to_string().into_diag_arg(path)
+                }
+            }
+        )+
+    }
+}
+
+macro_rules! into_diag_arg_for_number {
+    ($( $ty:ty ),+ $(,)?) => {
+        $(
+            impl $crate::IntoDiagArg for $ty {
+                fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> $crate::DiagArgValue {
+                    // Convert to a string if it won't fit into `Number`.
+                    #[allow(irrefutable_let_patterns)]
+                    if let Ok(n) = TryInto::<i32>::try_into(self) {
+                        $crate::DiagArgValue::Number(n)
+                    } else {
+                        self.to_string().into_diag_arg(path)
+                    }
+                }
+            }
+        )+
+    }
+}
+
+into_diag_arg_using_display!(
+    ast::ParamKindOrd,
+    std::io::Error,
+    Box<dyn std::error::Error>,
+    std::num::NonZero<u32>,
+    Edition,
+    rustc_span::Ident,
+    rustc_span::MacroRulesNormalizedIdent,
+    ParseIntError,
+    ExitStatus,
+);
+
+into_diag_arg_for_number!(i8, u8, i16, u16, i32, u32, i64, u64, i128, u128, isize, usize);
+
+impl IntoDiagArg for bool {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        if self {
+            DiagArgValue::Str(Cow::Borrowed("true"))
+        } else {
+            DiagArgValue::Str(Cow::Borrowed("false"))
+        }
+    }
+}
+
+impl IntoDiagArg for char {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Str(Cow::Owned(format!("{self:?}")))
+    }
+}
+
+impl IntoDiagArg for Vec<char> {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::StrListSepByAnd(
+            self.into_iter().map(|c| Cow::Owned(format!("{c:?}"))).collect(),
+        )
+    }
+}
+
+impl IntoDiagArg for rustc_span::Symbol {
+    fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        self.to_ident_string().into_diag_arg(path)
+    }
+}
+
+impl<'a> IntoDiagArg for &'a str {
+    fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        self.to_string().into_diag_arg(path)
+    }
+}
+
+impl IntoDiagArg for String {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Str(Cow::Owned(self))
+    }
+}
+
+impl<'a> IntoDiagArg for Cow<'a, str> {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Str(Cow::Owned(self.into_owned()))
+    }
+}
+
+impl<'a> IntoDiagArg for &'a Path {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Str(Cow::Owned(self.display().to_string()))
+    }
+}
+
+impl IntoDiagArg for PathBuf {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Str(Cow::Owned(self.display().to_string()))
+    }
+}
+
+impl IntoDiagArg for ast::Expr {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Str(Cow::Owned(pprust::expr_to_string(&self)))
+    }
+}
+
+impl IntoDiagArg for ast::Path {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Str(Cow::Owned(pprust::path_to_string(&self)))
+    }
+}
+
+impl IntoDiagArg for ast::token::Token {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Str(pprust::token_to_string(&self))
+    }
+}
+
+impl IntoDiagArg for ast::token::TokenKind {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Str(pprust::token_kind_to_string(&self))
+    }
+}
+
+impl IntoDiagArg for std::ffi::CString {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Str(Cow::Owned(self.to_string_lossy().into_owned()))
+    }
+}
+
+impl IntoDiagArg for rustc_data_structures::small_c_str::SmallCStr {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Str(Cow::Owned(self.to_string_lossy().into_owned()))
+    }
+}
+
+impl IntoDiagArg for ast::Visibility {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        let s = pprust::vis_to_string(&self);
+        let s = s.trim_end().to_string();
+        DiagArgValue::Str(Cow::Owned(s))
+    }
+}
+
+impl IntoDiagArg for Backtrace {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Str(Cow::from(self.to_string()))
+    }
+}
+
+impl IntoDiagArg for ast::util::parser::ExprPrecedence {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Number(self as i32)
+    }
+}
+
+impl IntoDiagArg for ast::FloatTy {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Str(Cow::Borrowed(self.name_str()))
+    }
+}
diff --git a/compiler/rustc_error_messages/src/lib.rs b/compiler/rustc_error_messages/src/lib.rs
index 4b3ecad307f..7b7843f6cf3 100644
--- a/compiler/rustc_error_messages/src/lib.rs
+++ b/compiler/rustc_error_messages/src/lib.rs
@@ -15,7 +15,6 @@ use fluent_bundle::FluentResource;
 pub use fluent_bundle::types::FluentType;
 pub use fluent_bundle::{self, FluentArgs, FluentError, FluentValue};
 use fluent_syntax::parser::ParserError;
-use icu_provider_adapters::fallback::{LocaleFallbackProvider, LocaleFallbacker};
 use intl_memoizer::concurrent::IntlLangMemoizer;
 use rustc_data_structures::sync::{DynSend, IntoDynSyncSend};
 use rustc_macros::{Decodable, Encodable};
@@ -23,6 +22,9 @@ use rustc_span::Span;
 use tracing::{instrument, trace};
 pub use unic_langid::{LanguageIdentifier, langid};
 
+mod diagnostic_impls;
+pub use diagnostic_impls::DiagArgFromDisplay;
+
 pub type FluentBundle =
     IntoDynSyncSend<fluent_bundle::bundle::FluentBundle<FluentResource, IntlLangMemoizer>>;
 
@@ -512,8 +514,8 @@ impl From<Vec<Span>> for MultiSpan {
     }
 }
 
-fn icu_locale_from_unic_langid(lang: LanguageIdentifier) -> Option<icu_locid::Locale> {
-    icu_locid::Locale::try_from_bytes(lang.to_string().as_bytes()).ok()
+fn icu_locale_from_unic_langid(lang: LanguageIdentifier) -> Option<icu_locale::Locale> {
+    icu_locale::Locale::try_from_str(&lang.to_string()).ok()
 }
 
 pub fn fluent_value_from_str_list_sep_by_and(l: Vec<Cow<'_, str>>) -> FluentValue<'_> {
@@ -565,21 +567,15 @@ pub fn fluent_value_from_str_list_sep_by_and(l: Vec<Cow<'_, str>>) -> FluentValu
         where
             Self: Sized,
         {
-            let baked_data_provider = rustc_baked_icu_data::baked_data_provider();
-            let locale_fallbacker =
-                LocaleFallbacker::try_new_with_any_provider(&baked_data_provider)
-                    .expect("Failed to create fallback provider");
-            let data_provider =
-                LocaleFallbackProvider::new_with_fallbacker(baked_data_provider, locale_fallbacker);
             let locale = icu_locale_from_unic_langid(lang)
                 .unwrap_or_else(|| rustc_baked_icu_data::supported_locales::EN);
-            let list_formatter =
-                icu_list::ListFormatter::try_new_and_with_length_with_any_provider(
-                    &data_provider,
-                    &locale.into(),
-                    icu_list::ListLength::Wide,
-                )
-                .expect("Failed to create list formatter");
+            let list_formatter = icu_list::ListFormatter::try_new_and_unstable(
+                &rustc_baked_icu_data::BakedDataProvider,
+                locale.into(),
+                icu_list::options::ListFormatterOptions::default()
+                    .with_length(icu_list::options::ListLength::Wide),
+            )
+            .expect("Failed to create list formatter");
 
             Ok(MemoizableListFormatter(list_formatter))
         }
@@ -589,3 +585,53 @@ pub fn fluent_value_from_str_list_sep_by_and(l: Vec<Cow<'_, str>>) -> FluentValu
 
     FluentValue::Custom(Box::new(FluentStrListSepByAnd(l)))
 }
+
+/// Simplified version of `FluentArg` that can implement `Encodable` and `Decodable`. Collection of
+/// `DiagArg` are converted to `FluentArgs` (consuming the collection) at the start of diagnostic
+/// emission.
+pub type DiagArg<'iter> = (&'iter DiagArgName, &'iter DiagArgValue);
+
+/// Name of a diagnostic argument.
+pub type DiagArgName = Cow<'static, str>;
+
+/// Simplified version of `FluentValue` that can implement `Encodable` and `Decodable`. Converted
+/// to a `FluentValue` by the emitter to be used in diagnostic translation.
+#[derive(Clone, Debug, PartialEq, Eq, Hash, Encodable, Decodable)]
+pub enum DiagArgValue {
+    Str(Cow<'static, str>),
+    // This gets converted to a `FluentNumber`, which is an `f64`. An `i32`
+    // safely fits in an `f64`. Any integers bigger than that will be converted
+    // to strings in `into_diag_arg` and stored using the `Str` variant.
+    Number(i32),
+    StrListSepByAnd(Vec<Cow<'static, str>>),
+}
+
+/// Converts a value of a type into a `DiagArg` (typically a field of an `Diag` struct).
+/// Implemented as a custom trait rather than `From` so that it is implemented on the type being
+/// converted rather than on `DiagArgValue`, which enables types from other `rustc_*` crates to
+/// implement this.
+pub trait IntoDiagArg {
+    /// Convert `Self` into a `DiagArgValue` suitable for rendering in a diagnostic.
+    ///
+    /// It takes a `path` where "long values" could be written to, if the `DiagArgValue` is too big
+    /// for displaying on the terminal. This path comes from the `Diag` itself. When rendering
+    /// values that come from `TyCtxt`, like `Ty<'_>`, they can use `TyCtxt::short_string`. If a
+    /// value has no shortening logic that could be used, the argument can be safely ignored.
+    fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue;
+}
+
+impl IntoDiagArg for DiagArgValue {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        self
+    }
+}
+
+impl From<DiagArgValue> for FluentValue<'static> {
+    fn from(val: DiagArgValue) -> Self {
+        match val {
+            DiagArgValue::Str(s) => From::from(s),
+            DiagArgValue::Number(n) => From::from(n),
+            DiagArgValue::StrListSepByAnd(l) => fluent_value_from_str_list_sep_by_and(l),
+        }
+    }
+}
diff --git a/compiler/rustc_errors/Cargo.toml b/compiler/rustc_errors/Cargo.toml
index 3e8cf6207ae..f5853855673 100644
--- a/compiler/rustc_errors/Cargo.toml
+++ b/compiler/rustc_errors/Cargo.toml
@@ -9,26 +9,22 @@ annotate-snippets = "0.11"
 derive_setters = "0.1.6"
 rustc_abi = { path = "../rustc_abi" }
 rustc_ast = { path = "../rustc_ast" }
-rustc_ast_pretty = { path = "../rustc_ast_pretty" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_error_codes = { path = "../rustc_error_codes" }
 rustc_error_messages = { path = "../rustc_error_messages" }
 rustc_fluent_macro = { path = "../rustc_fluent_macro" }
 rustc_hashes = { path = "../rustc_hashes" }
-rustc_hir = { path = "../rustc_hir" }
 rustc_index = { path = "../rustc_index" }
 rustc_lexer = { path = "../rustc_lexer" }
 rustc_lint_defs = { path = "../rustc_lint_defs" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_span = { path = "../rustc_span" }
-rustc_target = { path = "../rustc_target" }
-rustc_type_ir = { path = "../rustc_type_ir" }
 serde = { version = "1.0.125", features = ["derive"] }
 serde_json = "1.0.59"
 termcolor = "1.2.0"
 termize = "0.2"
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
 
 [target.'cfg(windows)'.dependencies.windows]
diff --git a/compiler/rustc_errors/src/codes.rs b/compiler/rustc_errors/src/codes.rs
index 947cf27ca79..787a8af99b1 100644
--- a/compiler/rustc_errors/src/codes.rs
+++ b/compiler/rustc_errors/src/codes.rs
@@ -20,6 +20,8 @@ impl fmt::Display for ErrCode {
     }
 }
 
+rustc_error_messages::into_diag_arg_using_display!(ErrCode);
+
 macro_rules! define_error_code_constants_and_diagnostics_table {
     ($($name:ident: $num:literal,)*) => (
         $(
diff --git a/compiler/rustc_errors/src/decorate_diag.rs b/compiler/rustc_errors/src/decorate_diag.rs
new file mode 100644
index 00000000000..5aef26ccf97
--- /dev/null
+++ b/compiler/rustc_errors/src/decorate_diag.rs
@@ -0,0 +1,85 @@
+/// This module provides types and traits for buffering lints until later in compilation.
+use rustc_ast::node_id::NodeId;
+use rustc_data_structures::fx::FxIndexMap;
+use rustc_error_messages::MultiSpan;
+use rustc_lint_defs::{BuiltinLintDiag, Lint, LintId};
+
+use crate::{DynSend, LintDiagnostic, LintDiagnosticBox};
+
+/// We can't implement `LintDiagnostic` for `BuiltinLintDiag`, because decorating some of its
+/// variants requires types we don't have yet. So, handle that case separately.
+pub enum DecorateDiagCompat {
+    Dynamic(Box<dyn for<'a> LintDiagnosticBox<'a, ()> + DynSend + 'static>),
+    Builtin(BuiltinLintDiag),
+}
+
+impl std::fmt::Debug for DecorateDiagCompat {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("DecorateDiagCompat").finish()
+    }
+}
+
+impl !LintDiagnostic<'_, ()> for BuiltinLintDiag {}
+
+impl<D: for<'a> LintDiagnostic<'a, ()> + DynSend + 'static> From<D> for DecorateDiagCompat {
+    #[inline]
+    fn from(d: D) -> Self {
+        Self::Dynamic(Box::new(d))
+    }
+}
+
+impl From<BuiltinLintDiag> for DecorateDiagCompat {
+    #[inline]
+    fn from(b: BuiltinLintDiag) -> Self {
+        Self::Builtin(b)
+    }
+}
+
+/// Lints that are buffered up early on in the `Session` before the
+/// `LintLevels` is calculated.
+#[derive(Debug)]
+pub struct BufferedEarlyLint {
+    /// The span of code that we are linting on.
+    pub span: Option<MultiSpan>,
+
+    /// The `NodeId` of the AST node that generated the lint.
+    pub node_id: NodeId,
+
+    /// A lint Id that can be passed to
+    /// `rustc_lint::early::EarlyContextAndPass::check_id`.
+    pub lint_id: LintId,
+
+    /// Customization of the `Diag<'_>` for the lint.
+    pub diagnostic: DecorateDiagCompat,
+}
+
+#[derive(Default, Debug)]
+pub struct LintBuffer {
+    pub map: FxIndexMap<NodeId, Vec<BufferedEarlyLint>>,
+}
+
+impl LintBuffer {
+    pub fn add_early_lint(&mut self, early_lint: BufferedEarlyLint) {
+        self.map.entry(early_lint.node_id).or_default().push(early_lint);
+    }
+
+    pub fn take(&mut self, id: NodeId) -> Vec<BufferedEarlyLint> {
+        // FIXME(#120456) - is `swap_remove` correct?
+        self.map.swap_remove(&id).unwrap_or_default()
+    }
+
+    pub fn buffer_lint(
+        &mut self,
+        lint: &'static Lint,
+        node_id: NodeId,
+        span: impl Into<MultiSpan>,
+        decorate: impl Into<DecorateDiagCompat>,
+    ) {
+        self.add_early_lint(BufferedEarlyLint {
+            lint_id: LintId::of(lint),
+            node_id,
+            span: Some(span.into()),
+            diagnostic: decorate.into(),
+        });
+    }
+}
diff --git a/compiler/rustc_errors/src/diagnostic.rs b/compiler/rustc_errors/src/diagnostic.rs
index 98be37fd84b..96a4ed3218f 100644
--- a/compiler/rustc_errors/src/diagnostic.rs
+++ b/compiler/rustc_errors/src/diagnostic.rs
@@ -8,7 +8,7 @@ use std::path::PathBuf;
 use std::thread::panicking;
 
 use rustc_data_structures::fx::FxIndexMap;
-use rustc_error_messages::{FluentValue, fluent_value_from_str_list_sep_by_and};
+use rustc_error_messages::{DiagArgName, DiagArgValue, IntoDiagArg};
 use rustc_lint_defs::{Applicability, LintExpectationId};
 use rustc_macros::{Decodable, Encodable};
 use rustc_span::source_map::Spanned;
@@ -22,26 +22,6 @@ use crate::{
     Suggestions,
 };
 
-/// Simplified version of `FluentArg` that can implement `Encodable` and `Decodable`. Collection of
-/// `DiagArg` are converted to `FluentArgs` (consuming the collection) at the start of diagnostic
-/// emission.
-pub type DiagArg<'iter> = (&'iter DiagArgName, &'iter DiagArgValue);
-
-/// Name of a diagnostic argument.
-pub type DiagArgName = Cow<'static, str>;
-
-/// Simplified version of `FluentValue` that can implement `Encodable` and `Decodable`. Converted
-/// to a `FluentValue` by the emitter to be used in diagnostic translation.
-#[derive(Clone, Debug, PartialEq, Eq, Hash, Encodable, Decodable)]
-pub enum DiagArgValue {
-    Str(Cow<'static, str>),
-    // This gets converted to a `FluentNumber`, which is an `f64`. An `i32`
-    // safely fits in an `f64`. Any integers bigger than that will be converted
-    // to strings in `into_diag_arg` and stored using the `Str` variant.
-    Number(i32),
-    StrListSepByAnd(Vec<Cow<'static, str>>),
-}
-
 pub type DiagArgMap = FxIndexMap<DiagArgName, DiagArgValue>;
 
 /// Trait for types that `Diag::emit` can return as a "guarantee" (or "proof")
@@ -143,36 +123,6 @@ where
     }
 }
 
-/// Converts a value of a type into a `DiagArg` (typically a field of an `Diag` struct).
-/// Implemented as a custom trait rather than `From` so that it is implemented on the type being
-/// converted rather than on `DiagArgValue`, which enables types from other `rustc_*` crates to
-/// implement this.
-pub trait IntoDiagArg {
-    /// Convert `Self` into a `DiagArgValue` suitable for rendering in a diagnostic.
-    ///
-    /// It takes a `path` where "long values" could be written to, if the `DiagArgValue` is too big
-    /// for displaying on the terminal. This path comes from the `Diag` itself. When rendering
-    /// values that come from `TyCtxt`, like `Ty<'_>`, they can use `TyCtxt::short_string`. If a
-    /// value has no shortening logic that could be used, the argument can be safely ignored.
-    fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue;
-}
-
-impl IntoDiagArg for DiagArgValue {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        self
-    }
-}
-
-impl From<DiagArgValue> for FluentValue<'static> {
-    fn from(val: DiagArgValue) -> Self {
-        match val {
-            DiagArgValue::Str(s) => From::from(s),
-            DiagArgValue::Number(n) => From::from(n),
-            DiagArgValue::StrListSepByAnd(l) => fluent_value_from_str_list_sep_by_and(l),
-        }
-    }
-}
-
 /// Trait implemented by error types. This should not be implemented manually. Instead, use
 /// `#[derive(Subdiagnostic)]` -- see [rustc_macros::Subdiagnostic].
 #[rustc_diagnostic_item = "Subdiagnostic"]
@@ -188,10 +138,20 @@ where
 /// `#[derive(LintDiagnostic)]` -- see [rustc_macros::LintDiagnostic].
 #[rustc_diagnostic_item = "LintDiagnostic"]
 pub trait LintDiagnostic<'a, G: EmissionGuarantee> {
-    /// Decorate and emit a lint.
+    /// Decorate a lint with the information from this type.
     fn decorate_lint<'b>(self, diag: &'b mut Diag<'a, G>);
 }
 
+pub trait LintDiagnosticBox<'a, G: EmissionGuarantee> {
+    fn decorate_lint_box<'b>(self: Box<Self>, diag: &'b mut Diag<'a, G>);
+}
+
+impl<'a, G: EmissionGuarantee, D: LintDiagnostic<'a, G>> LintDiagnosticBox<'a, G> for D {
+    fn decorate_lint_box<'b>(self: Box<Self>, diag: &'b mut Diag<'a, G>) {
+        self.decorate_lint(diag);
+    }
+}
+
 #[derive(Clone, Debug, Encodable, Decodable)]
 pub(crate) struct DiagLocation {
     file: Cow<'static, str>,
@@ -617,6 +577,29 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
         self.level = Level::DelayedBug;
     }
 
+    /// Make emitting this diagnostic fatal
+    ///
+    /// Changes the level of this diagnostic to Fatal, and importantly also changes the emission guarantee.
+    /// This is sound for errors that would otherwise be printed, but now simply exit the process instead.
+    /// This function still gives an emission guarantee, the guarantee is now just that it exits fatally.
+    /// For delayed bugs this is different, since those are buffered. If we upgrade one to fatal, another
+    /// might now be ignored.
+    #[rustc_lint_diagnostics]
+    #[track_caller]
+    pub fn upgrade_to_fatal(mut self) -> Diag<'a, FatalAbort> {
+        assert!(
+            matches!(self.level, Level::Error),
+            "upgrade_to_fatal: cannot upgrade {:?} to Fatal: not an error",
+            self.level
+        );
+        self.level = Level::Fatal;
+
+        // Take is okay since we immediately rewrap it in another diagnostic.
+        // i.e. we do emit it despite defusing the original diagnostic's drop bomb.
+        let diag = self.diag.take();
+        Diag { dcx: self.dcx, diag, _marker: PhantomData }
+    }
+
     with_fn! { with_span_label,
     /// Appends a labeled span to the diagnostic.
     ///
@@ -1113,7 +1096,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
             .map(|snippet| {
                 debug_assert!(
                     !(sp.is_empty() && snippet.is_empty()),
-                    "Span must not be empty and have no suggestion"
+                    "Span `{sp:?}` must not be empty and have no suggestion"
                 );
                 Substitution { parts: vec![SubstitutionPart { snippet, span: sp }] }
             })
diff --git a/compiler/rustc_errors/src/diagnostic_impls.rs b/compiler/rustc_errors/src/diagnostic_impls.rs
index eca5806fac5..435d16a8380 100644
--- a/compiler/rustc_errors/src/diagnostic_impls.rs
+++ b/compiler/rustc_errors/src/diagnostic_impls.rs
@@ -1,317 +1,22 @@
-use std::backtrace::Backtrace;
 use std::borrow::Cow;
-use std::fmt;
-use std::num::ParseIntError;
-use std::path::{Path, PathBuf};
-use std::process::ExitStatus;
 
 use rustc_abi::TargetDataLayoutErrors;
-use rustc_ast::util::parser::ExprPrecedence;
-use rustc_ast_pretty::pprust;
-use rustc_hir::RustcVersion;
+use rustc_error_messages::{DiagArgValue, IntoDiagArg};
 use rustc_macros::Subdiagnostic;
-use rustc_span::edition::Edition;
-use rustc_span::{Ident, MacroRulesNormalizedIdent, Span, Symbol};
-use rustc_target::spec::{PanicStrategy, SplitDebuginfo, StackProtector, TargetTuple};
-use rustc_type_ir::{ClosureKind, FloatTy};
-use {rustc_ast as ast, rustc_hir as hir};
+use rustc_span::{Span, Symbol};
 
 use crate::diagnostic::DiagLocation;
 use crate::{
-    Diag, DiagArgValue, DiagCtxtHandle, Diagnostic, EmissionGuarantee, ErrCode, IntoDiagArg, Level,
-    Subdiagnostic, fluent_generated as fluent,
+    Diag, DiagCtxtHandle, Diagnostic, EmissionGuarantee, Level, Subdiagnostic,
+    fluent_generated as fluent,
 };
 
-pub struct DiagArgFromDisplay<'a>(pub &'a dyn fmt::Display);
-
-impl IntoDiagArg for DiagArgFromDisplay<'_> {
-    fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        self.0.to_string().into_diag_arg(path)
-    }
-}
-
-impl<'a> From<&'a dyn fmt::Display> for DiagArgFromDisplay<'a> {
-    fn from(t: &'a dyn fmt::Display) -> Self {
-        DiagArgFromDisplay(t)
-    }
-}
-
-impl<'a, T: fmt::Display> From<&'a T> for DiagArgFromDisplay<'a> {
-    fn from(t: &'a T) -> Self {
-        DiagArgFromDisplay(t)
-    }
-}
-
-impl<'a, T: Clone + IntoDiagArg> IntoDiagArg for &'a T {
-    fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        self.clone().into_diag_arg(path)
-    }
-}
-
-#[macro_export]
-macro_rules! into_diag_arg_using_display {
-    ($( $ty:ty ),+ $(,)?) => {
-        $(
-            impl IntoDiagArg for $ty {
-                fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-                    self.to_string().into_diag_arg(path)
-                }
-            }
-        )+
-    }
-}
-
-macro_rules! into_diag_arg_for_number {
-    ($( $ty:ty ),+ $(,)?) => {
-        $(
-            impl IntoDiagArg for $ty {
-                fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-                    // Convert to a string if it won't fit into `Number`.
-                    #[allow(irrefutable_let_patterns)]
-                    if let Ok(n) = TryInto::<i32>::try_into(self) {
-                        DiagArgValue::Number(n)
-                    } else {
-                        self.to_string().into_diag_arg(path)
-                    }
-                }
-            }
-        )+
-    }
-}
-
-into_diag_arg_using_display!(
-    ast::ParamKindOrd,
-    std::io::Error,
-    Box<dyn std::error::Error>,
-    std::num::NonZero<u32>,
-    hir::Target,
-    Edition,
-    Ident,
-    MacroRulesNormalizedIdent,
-    ParseIntError,
-    StackProtector,
-    &TargetTuple,
-    SplitDebuginfo,
-    ExitStatus,
-    ErrCode,
-    rustc_abi::ExternAbi,
-);
-
-impl IntoDiagArg for RustcVersion {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(Cow::Owned(self.to_string()))
-    }
-}
-
-impl<I: rustc_type_ir::Interner> IntoDiagArg for rustc_type_ir::TraitRef<I> {
-    fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        self.to_string().into_diag_arg(path)
-    }
-}
-
-impl<I: rustc_type_ir::Interner> IntoDiagArg for rustc_type_ir::ExistentialTraitRef<I> {
-    fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        self.to_string().into_diag_arg(path)
-    }
-}
-
-impl<I: rustc_type_ir::Interner> IntoDiagArg for rustc_type_ir::UnevaluatedConst<I> {
-    fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        format!("{self:?}").into_diag_arg(path)
-    }
-}
-
-impl<I: rustc_type_ir::Interner> IntoDiagArg for rustc_type_ir::FnSig<I> {
-    fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        format!("{self:?}").into_diag_arg(path)
-    }
-}
-
-impl<I: rustc_type_ir::Interner, T> IntoDiagArg for rustc_type_ir::Binder<I, T>
-where
-    T: IntoDiagArg,
-{
-    fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        self.skip_binder().into_diag_arg(path)
-    }
-}
-
-into_diag_arg_for_number!(i8, u8, i16, u16, i32, u32, i64, u64, i128, u128, isize, usize);
-
-impl IntoDiagArg for bool {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        if self {
-            DiagArgValue::Str(Cow::Borrowed("true"))
-        } else {
-            DiagArgValue::Str(Cow::Borrowed("false"))
-        }
-    }
-}
-
-impl IntoDiagArg for char {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(Cow::Owned(format!("{self:?}")))
-    }
-}
-
-impl IntoDiagArg for Vec<char> {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::StrListSepByAnd(
-            self.into_iter().map(|c| Cow::Owned(format!("{c:?}"))).collect(),
-        )
-    }
-}
-
-impl IntoDiagArg for Symbol {
-    fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        self.to_ident_string().into_diag_arg(path)
-    }
-}
-
-impl<'a> IntoDiagArg for &'a str {
-    fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        self.to_string().into_diag_arg(path)
-    }
-}
-
-impl IntoDiagArg for String {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(Cow::Owned(self))
-    }
-}
-
-impl<'a> IntoDiagArg for Cow<'a, str> {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(Cow::Owned(self.into_owned()))
-    }
-}
-
-impl<'a> IntoDiagArg for &'a Path {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(Cow::Owned(self.display().to_string()))
-    }
-}
-
-impl IntoDiagArg for PathBuf {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(Cow::Owned(self.display().to_string()))
-    }
-}
-
-impl IntoDiagArg for PanicStrategy {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(Cow::Owned(self.desc().to_string()))
-    }
-}
-
-impl IntoDiagArg for hir::ConstContext {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(Cow::Borrowed(match self {
-            hir::ConstContext::ConstFn => "const_fn",
-            hir::ConstContext::Static(_) => "static",
-            hir::ConstContext::Const { .. } => "const",
-        }))
-    }
-}
-
-impl IntoDiagArg for ast::Expr {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(Cow::Owned(pprust::expr_to_string(&self)))
-    }
-}
-
-impl IntoDiagArg for ast::Path {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(Cow::Owned(pprust::path_to_string(&self)))
-    }
-}
-
-impl IntoDiagArg for ast::token::Token {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(pprust::token_to_string(&self))
-    }
-}
-
-impl IntoDiagArg for ast::token::TokenKind {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(pprust::token_kind_to_string(&self))
-    }
-}
-
-impl IntoDiagArg for FloatTy {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(Cow::Borrowed(self.name_str()))
-    }
-}
-
-impl IntoDiagArg for std::ffi::CString {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(Cow::Owned(self.to_string_lossy().into_owned()))
-    }
-}
-
-impl IntoDiagArg for rustc_data_structures::small_c_str::SmallCStr {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(Cow::Owned(self.to_string_lossy().into_owned()))
-    }
-}
-
-impl IntoDiagArg for ast::Visibility {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        let s = pprust::vis_to_string(&self);
-        let s = s.trim_end().to_string();
-        DiagArgValue::Str(Cow::Owned(s))
-    }
-}
-
-impl IntoDiagArg for rustc_lint_defs::Level {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(Cow::Borrowed(self.to_cmd_flag()))
-    }
-}
-
-impl<Id> IntoDiagArg for hir::def::Res<Id> {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(Cow::Borrowed(self.descr()))
-    }
-}
-
 impl IntoDiagArg for DiagLocation {
     fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
         DiagArgValue::Str(Cow::from(self.to_string()))
     }
 }
 
-impl IntoDiagArg for Backtrace {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(Cow::from(self.to_string()))
-    }
-}
-
-impl IntoDiagArg for Level {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(Cow::from(self.to_string()))
-    }
-}
-
-impl IntoDiagArg for ClosureKind {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(self.as_str().into())
-    }
-}
-
-impl IntoDiagArg for hir::def::Namespace {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Str(Cow::Borrowed(self.descr()))
-    }
-}
-
-impl IntoDiagArg for ExprPrecedence {
-    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
-        DiagArgValue::Number(self as i32)
-    }
-}
-
 #[derive(Clone)]
 pub struct DiagSymbolList<S = Symbol>(Vec<S>);
 
diff --git a/compiler/rustc_errors/src/emitter.rs b/compiler/rustc_errors/src/emitter.rs
index 97c47fa9b9a..b94370e8e9b 100644
--- a/compiler/rustc_errors/src/emitter.rs
+++ b/compiler/rustc_errors/src/emitter.rs
@@ -17,7 +17,7 @@ use std::path::Path;
 use std::sync::Arc;
 
 use derive_setters::Setters;
-use rustc_data_structures::fx::{FxHashMap, FxIndexMap, FxIndexSet};
+use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
 use rustc_data_structures::sync::{DynSend, IntoDynSyncSend};
 use rustc_error_messages::{FluentArgs, SpanLabel};
 use rustc_lexer;
@@ -1462,7 +1462,7 @@ impl HumanEmitter {
         max_line_num_len: usize,
         is_secondary: bool,
         is_cont: bool,
-    ) -> io::Result<()> {
+    ) -> io::Result<CodeWindowStatus> {
         let mut buffer = StyledBuffer::new();
 
         if !msp.has_primary_spans() && !msp.has_span_labels() && is_secondary && !self.short_message
@@ -1575,12 +1575,14 @@ impl HumanEmitter {
         }
         let mut annotated_files = FileWithAnnotatedLines::collect_annotations(self, args, msp);
         trace!("{annotated_files:#?}");
+        let mut code_window_status = CodeWindowStatus::Open;
 
         // Make sure our primary file comes first
         let primary_span = msp.primary_span().unwrap_or_default();
         let (Some(sm), false) = (self.sm.as_ref(), primary_span.is_dummy()) else {
             // If we don't have span information, emit and exit
-            return emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message);
+            return emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)
+                .map(|_| code_window_status);
         };
         let primary_lo = sm.lookup_char_pos(primary_span.lo());
         if let Ok(pos) =
@@ -1589,6 +1591,9 @@ impl HumanEmitter {
             annotated_files.swap(0, pos);
         }
 
+        // An end column separator should be emitted when a file with with a
+        // source, is followed by one without a source
+        let mut col_sep_before_no_show_source = false;
         let annotated_files_len = annotated_files.len();
         // Print out the annotate source lines that correspond with the error
         for (file_idx, annotated_file) in annotated_files.into_iter().enumerate() {
@@ -1599,6 +1604,26 @@ impl HumanEmitter {
                 &annotated_file.file,
             ) {
                 if !self.short_message {
+                    // Add an end column separator when a file without a source
+                    // comes after one with a source
+                    //    ╭▸ $DIR/deriving-meta-unknown-trait.rs:1:10
+                    //    │
+                    // LL │ #[derive(Eqr)]
+                    //    │          ━━━
+                    //    ╰╴ (<- It prints *this* line)
+                    //    ╭▸ $SRC_DIR/core/src/cmp.rs:356:0
+                    //    │
+                    //    ╰╴note: similarly named derive macro `Eq` defined here
+                    if col_sep_before_no_show_source {
+                        let buffer_msg_line_offset = buffer.num_lines();
+                        self.draw_col_separator_end(
+                            &mut buffer,
+                            buffer_msg_line_offset,
+                            max_line_num_len + 1,
+                        );
+                    }
+                    col_sep_before_no_show_source = false;
+
                     // We'll just print an unannotated message.
                     for (annotation_id, line) in annotated_file.lines.iter().enumerate() {
                         let mut annotations = line.annotations.clone();
@@ -1639,29 +1664,42 @@ impl HumanEmitter {
                             }
                             line_idx += 1;
                         }
-                        for (label, is_primary) in labels.into_iter() {
+                        if is_cont
+                            && file_idx == annotated_files_len - 1
+                            && annotation_id == annotated_file.lines.len() - 1
+                            && !labels.is_empty()
+                        {
+                            code_window_status = CodeWindowStatus::Closed;
+                        }
+                        let labels_len = labels.len();
+                        for (label_idx, (label, is_primary)) in labels.into_iter().enumerate() {
                             let style = if is_primary {
                                 Style::LabelPrimary
                             } else {
                                 Style::LabelSecondary
                             };
-                            let pipe = self.col_separator();
-                            buffer.prepend(line_idx, &format!(" {pipe}"), Style::LineNumber);
-                            for _ in 0..max_line_num_len {
-                                buffer.prepend(line_idx, " ", Style::NoStyle);
-                            }
+                            self.draw_col_separator_no_space(
+                                &mut buffer,
+                                line_idx,
+                                max_line_num_len + 1,
+                            );
                             line_idx += 1;
-                            let chr = self.note_separator();
-                            buffer.append(line_idx, &format!(" {chr} note: "), style);
-                            for _ in 0..max_line_num_len {
-                                buffer.prepend(line_idx, " ", Style::NoStyle);
-                            }
+                            self.draw_note_separator(
+                                &mut buffer,
+                                line_idx,
+                                max_line_num_len + 1,
+                                label_idx != labels_len - 1,
+                            );
+                            buffer.append(line_idx, "note", Style::MainHeaderMsg);
+                            buffer.append(line_idx, ": ", Style::NoStyle);
                             buffer.append(line_idx, label, style);
                             line_idx += 1;
                         }
                     }
                 }
                 continue;
+            } else {
+                col_sep_before_no_show_source = true;
             }
 
             // print out the span location and spacer before we print the annotated source
@@ -1853,7 +1891,7 @@ impl HumanEmitter {
                             && line_idx + 1 == annotated_file.lines.len(),
                     );
 
-                    let mut to_add = FxHashMap::default();
+                    let mut to_add = FxIndexMap::default();
 
                     for (depth, style) in depths {
                         // FIXME(#120456) - is `swap_remove` correct?
@@ -1976,7 +2014,7 @@ impl HumanEmitter {
         // final step: take our styled buffer, render it, then output it
         emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)?;
 
-        Ok(())
+        Ok(code_window_status)
     }
 
     fn column_width(&self, code_offset: usize) -> usize {
@@ -2491,7 +2529,7 @@ impl HumanEmitter {
             !children.is_empty()
                 || suggestions.iter().any(|s| s.style != SuggestionStyle::CompletelyHidden),
         ) {
-            Ok(()) => {
+            Ok(code_window_status) => {
                 if !children.is_empty()
                     || suggestions.iter().any(|s| s.style != SuggestionStyle::CompletelyHidden)
                 {
@@ -2502,7 +2540,7 @@ impl HumanEmitter {
                         {
                             // We'll continue the vertical bar to point into the next note.
                             self.draw_col_separator_no_space(&mut buffer, 0, max_line_num_len + 1);
-                        } else {
+                        } else if matches!(code_window_status, CodeWindowStatus::Open) {
                             // We'll close the vertical bar to visually end the code window.
                             self.draw_col_separator_end(&mut buffer, 0, max_line_num_len + 1);
                         }
@@ -2829,10 +2867,11 @@ impl HumanEmitter {
         }
     }
 
-    fn note_separator(&self) -> char {
+    fn note_separator(&self, is_cont: bool) -> &'static str {
         match self.theme {
-            OutputTheme::Ascii => '=',
-            OutputTheme::Unicode => '╰',
+            OutputTheme::Ascii => "= ",
+            OutputTheme::Unicode if is_cont => "├ ",
+            OutputTheme::Unicode => "╰ ",
         }
     }
 
@@ -2945,11 +2984,7 @@ impl HumanEmitter {
         col: usize,
         is_cont: bool,
     ) {
-        let chr = match self.theme {
-            OutputTheme::Ascii => "= ",
-            OutputTheme::Unicode if is_cont => "├ ",
-            OutputTheme::Unicode => "╰ ",
-        };
+        let chr = self.note_separator(is_cont);
         buffer.puts(line, col, chr, Style::LineNumber);
     }
 
@@ -3050,6 +3085,12 @@ enum DisplaySuggestion {
     Add,
 }
 
+#[derive(Clone, Copy, Debug)]
+enum CodeWindowStatus {
+    Closed,
+    Open,
+}
+
 impl FileWithAnnotatedLines {
     /// Preprocess all the annotations so that they are grouped by file and by line number
     /// This helps us quickly iterate over the whole message (including secondary file spans)
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index 2534cddf105..71fc54f0d33 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -40,13 +40,13 @@ use std::{fmt, panic};
 
 use Level::*;
 pub use codes::*;
+pub use decorate_diag::{BufferedEarlyLint, DecorateDiagCompat, LintBuffer};
 pub use diagnostic::{
-    BugAbort, Diag, DiagArg, DiagArgMap, DiagArgName, DiagArgValue, DiagInner, DiagStyledString,
-    Diagnostic, EmissionGuarantee, FatalAbort, IntoDiagArg, LintDiagnostic, StringPart, Subdiag,
-    Subdiagnostic,
+    BugAbort, Diag, DiagArgMap, DiagInner, DiagStyledString, Diagnostic, EmissionGuarantee,
+    FatalAbort, LintDiagnostic, LintDiagnosticBox, StringPart, Subdiag, Subdiagnostic,
 };
 pub use diagnostic_impls::{
-    DiagArgFromDisplay, DiagSymbolList, ElidedLifetimeInPathSubdiag, ExpectedLifetimeParameter,
+    DiagSymbolList, ElidedLifetimeInPathSubdiag, ExpectedLifetimeParameter,
     IndicateAnonymousLifetime, SingleLabelManySpans,
 };
 pub use emitter::ColorConfig;
@@ -56,11 +56,11 @@ use rustc_data_structures::fx::{FxHashSet, FxIndexMap, FxIndexSet};
 use rustc_data_structures::stable_hasher::StableHasher;
 use rustc_data_structures::sync::{DynSend, Lock};
 pub use rustc_error_messages::{
-    DiagMessage, FluentBundle, LanguageIdentifier, LazyFallbackBundle, MultiSpan, SpanLabel,
-    SubdiagMessage, fallback_fluent_bundle, fluent_bundle,
+    DiagArg, DiagArgFromDisplay, DiagArgName, DiagArgValue, DiagMessage, FluentBundle, IntoDiagArg,
+    LanguageIdentifier, LazyFallbackBundle, MultiSpan, SpanLabel, SubdiagMessage,
+    fallback_fluent_bundle, fluent_bundle, into_diag_arg_using_display,
 };
 use rustc_hashes::Hash128;
-use rustc_hir::HirId;
 pub use rustc_lint_defs::{Applicability, listify, pluralize};
 use rustc_lint_defs::{Lint, LintExpectationId};
 use rustc_macros::{Decodable, Encodable};
@@ -80,6 +80,7 @@ use crate::timings::TimingRecord;
 
 pub mod annotate_snippet_emitter_writer;
 pub mod codes;
+mod decorate_diag;
 mod diagnostic;
 mod diagnostic_impls;
 pub mod emitter;
@@ -108,13 +109,14 @@ rustc_data_structures::static_assert_size!(PResult<'_, bool>, 24);
 /// Used to avoid depending on `rustc_middle` in `rustc_attr_parsing`.
 /// Always the `TyCtxt`.
 pub trait LintEmitter: Copy {
+    type Id: Copy;
     #[track_caller]
     fn emit_node_span_lint(
         self,
         lint: &'static Lint,
-        hir_id: HirId,
+        hir_id: Self::Id,
         span: impl Into<MultiSpan>,
-        decorator: impl for<'a> LintDiagnostic<'a, ()>,
+        decorator: impl for<'a> LintDiagnostic<'a, ()> + DynSend + 'static,
     );
 }
 
@@ -1999,6 +2001,12 @@ impl Level {
     }
 }
 
+impl IntoDiagArg for Level {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Str(Cow::from(self.to_string()))
+    }
+}
+
 // FIXME(eddyb) this doesn't belong here AFAICT, should be moved to callsite.
 pub fn elided_lifetime_in_path_suggestion(
     source_map: &SourceMap,
diff --git a/compiler/rustc_expand/Cargo.toml b/compiler/rustc_expand/Cargo.toml
index f897833d85c..9bb7143af51 100644
--- a/compiler/rustc_expand/Cargo.toml
+++ b/compiler/rustc_expand/Cargo.toml
@@ -29,6 +29,6 @@ rustc_serialize = { path = "../rustc_serialize" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec = "0.2.12"
-tracing = "0.1"
+thin-vec.workspace = true
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_expand/messages.ftl b/compiler/rustc_expand/messages.ftl
index 1f8f3be6809..61ba716d082 100644
--- a/compiler/rustc_expand/messages.ftl
+++ b/compiler/rustc_expand/messages.ftl
@@ -70,7 +70,7 @@ expand_invalid_fragment_specifier =
     invalid fragment specifier `{$fragment}`
     .help = {$help}
 
-expand_macro_args_bad_delim = macro attribute argument matchers require parentheses
+expand_macro_args_bad_delim = `{$rule_kw}` rule argument matchers require parentheses
 expand_macro_args_bad_delim_sugg = the delimiters should be `(` and `)`
 
 expand_macro_body_stability =
diff --git a/compiler/rustc_expand/src/base.rs b/compiler/rustc_expand/src/base.rs
index 7da3bf27eb5..8ff21509f4a 100644
--- a/compiler/rustc_expand/src/base.rs
+++ b/compiler/rustc_expand/src/base.rs
@@ -13,12 +13,13 @@ use rustc_ast::visit::{AssocCtxt, Visitor};
 use rustc_ast::{self as ast, AttrVec, Attribute, HasAttrs, Item, NodeId, PatKind};
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
 use rustc_data_structures::sync;
-use rustc_errors::{DiagCtxtHandle, ErrorGuaranteed, PResult};
+use rustc_errors::{BufferedEarlyLint, DiagCtxtHandle, ErrorGuaranteed, PResult};
 use rustc_feature::Features;
 use rustc_hir as hir;
 use rustc_hir::attrs::{AttributeKind, CfgEntry, Deprecation};
+use rustc_hir::def::MacroKinds;
 use rustc_hir::{Stability, find_attr};
-use rustc_lint_defs::{BufferedEarlyLint, RegisteredTools};
+use rustc_lint_defs::RegisteredTools;
 use rustc_parse::MACRO_ARGUMENTS;
 use rustc_parse::parser::{ForceCollect, Parser};
 use rustc_session::config::CollapseMacroDebuginfo;
@@ -718,6 +719,9 @@ impl MacResult for DummyResult {
 /// A syntax extension kind.
 #[derive(Clone)]
 pub enum SyntaxExtensionKind {
+    /// A `macro_rules!` macro that can work as any `MacroKind`
+    MacroRules(Arc<crate::MacroRulesMacroExpander>),
+
     /// A token-based function-like macro.
     Bang(
         /// An expander with signature TokenStream -> TokenStream.
@@ -772,9 +776,39 @@ pub enum SyntaxExtensionKind {
     ),
 
     /// A glob delegation.
+    ///
+    /// This is for delegated function implementations, and has nothing to do with glob imports.
     GlobDelegation(Arc<dyn GlobDelegationExpander + sync::DynSync + sync::DynSend>),
 }
 
+impl SyntaxExtensionKind {
+    /// Returns `Some(expander)` for a macro usable as a `LegacyBang`; otherwise returns `None`
+    ///
+    /// This includes a `MacroRules` with function-like rules.
+    pub fn as_legacy_bang(&self) -> Option<&(dyn TTMacroExpander + sync::DynSync + sync::DynSend)> {
+        match self {
+            SyntaxExtensionKind::LegacyBang(exp) => Some(exp.as_ref()),
+            SyntaxExtensionKind::MacroRules(exp) if exp.kinds().contains(MacroKinds::BANG) => {
+                Some(exp.as_ref())
+            }
+            _ => None,
+        }
+    }
+
+    /// Returns `Some(expander)` for a macro usable as an `Attr`; otherwise returns `None`
+    ///
+    /// This includes a `MacroRules` with `attr` rules.
+    pub fn as_attr(&self) -> Option<&(dyn AttrProcMacro + sync::DynSync + sync::DynSend)> {
+        match self {
+            SyntaxExtensionKind::Attr(exp) => Some(exp.as_ref()),
+            SyntaxExtensionKind::MacroRules(exp) if exp.kinds().contains(MacroKinds::ATTR) => {
+                Some(exp.as_ref())
+            }
+            _ => None,
+        }
+    }
+}
+
 /// A struct representing a macro definition in "lowered" form ready for expansion.
 pub struct SyntaxExtension {
     /// A syntax extension kind.
@@ -804,18 +838,19 @@ pub struct SyntaxExtension {
 }
 
 impl SyntaxExtension {
-    /// Returns which kind of macro calls this syntax extension.
-    pub fn macro_kind(&self) -> MacroKind {
+    /// Returns which kinds of macro call this syntax extension.
+    pub fn macro_kinds(&self) -> MacroKinds {
         match self.kind {
             SyntaxExtensionKind::Bang(..)
             | SyntaxExtensionKind::LegacyBang(..)
-            | SyntaxExtensionKind::GlobDelegation(..) => MacroKind::Bang,
+            | SyntaxExtensionKind::GlobDelegation(..) => MacroKinds::BANG,
             SyntaxExtensionKind::Attr(..)
             | SyntaxExtensionKind::LegacyAttr(..)
-            | SyntaxExtensionKind::NonMacroAttr => MacroKind::Attr,
+            | SyntaxExtensionKind::NonMacroAttr => MacroKinds::ATTR,
             SyntaxExtensionKind::Derive(..) | SyntaxExtensionKind::LegacyDerive(..) => {
-                MacroKind::Derive
+                MacroKinds::DERIVE
             }
+            SyntaxExtensionKind::MacroRules(ref m) => m.kinds(),
         }
     }
 
@@ -1024,11 +1059,12 @@ impl SyntaxExtension {
         parent: LocalExpnId,
         call_site: Span,
         descr: Symbol,
+        kind: MacroKind,
         macro_def_id: Option<DefId>,
         parent_module: Option<DefId>,
     ) -> ExpnData {
         ExpnData::new(
-            ExpnKind::Macro(self.macro_kind(), descr),
+            ExpnKind::Macro(kind, descr),
             parent.to_expn_id(),
             call_site,
             self.span,
diff --git a/compiler/rustc_expand/src/config.rs b/compiler/rustc_expand/src/config.rs
index 83a8d601afe..15419ab7423 100644
--- a/compiler/rustc_expand/src/config.rs
+++ b/compiler/rustc_expand/src/config.rs
@@ -11,8 +11,10 @@ use rustc_ast::{
     NodeId, NormalAttr,
 };
 use rustc_attr_parsing as attr;
+use rustc_attr_parsing::validate_attr::deny_builtin_meta_unsafety;
 use rustc_attr_parsing::{
     AttributeParser, CFG_TEMPLATE, EvalConfigResult, ShouldEmit, eval_config_entry, parse_cfg_attr,
+    validate_attr,
 };
 use rustc_data_structures::flat_map_in_place::FlatMapInPlace;
 use rustc_feature::{
@@ -20,8 +22,6 @@ use rustc_feature::{
     REMOVED_LANG_FEATURES, UNSTABLE_LANG_FEATURES,
 };
 use rustc_lint_defs::BuiltinLintDiag;
-use rustc_parse::validate_attr;
-use rustc_parse::validate_attr::deny_builtin_meta_unsafety;
 use rustc_session::Session;
 use rustc_session::parse::feature_err;
 use rustc_span::{STDLIB_STABLE_CRATES, Span, Symbol, sym};
@@ -415,16 +415,6 @@ impl<'a> StripUnconfigured<'a> {
         node: NodeId,
         emit_errors: ShouldEmit,
     ) -> EvalConfigResult {
-        // We need to run this to do basic validation of the attribute, such as that lits are valid, etc
-        // FIXME(jdonszelmann) this should not be necessary in the future
-        match validate_attr::parse_meta(&self.sess.psess, attr) {
-            Ok(_) => {}
-            Err(err) => {
-                err.emit();
-                return EvalConfigResult::True;
-            }
-        }
-
         // Unsafety check needs to be done explicitly here because this attribute will be removed before the normal check
         deny_builtin_meta_unsafety(
             self.sess.dcx(),
diff --git a/compiler/rustc_expand/src/errors.rs b/compiler/rustc_expand/src/errors.rs
index e58269991fc..ba9d76970f0 100644
--- a/compiler/rustc_expand/src/errors.rs
+++ b/compiler/rustc_expand/src/errors.rs
@@ -490,6 +490,7 @@ pub(crate) struct MacroArgsBadDelim {
     pub span: Span,
     #[subdiagnostic]
     pub sugg: MacroArgsBadDelimSugg,
+    pub rule_kw: Symbol,
 }
 
 #[derive(Subdiagnostic)]
diff --git a/compiler/rustc_expand/src/expand.rs b/compiler/rustc_expand/src/expand.rs
index e7ae4416968..dbb4a9de9e0 100644
--- a/compiler/rustc_expand/src/expand.rs
+++ b/compiler/rustc_expand/src/expand.rs
@@ -1,7 +1,7 @@
 use std::path::PathBuf;
 use std::rc::Rc;
 use std::sync::Arc;
-use std::{iter, mem};
+use std::{iter, mem, slice};
 
 use rustc_ast::mut_visit::*;
 use rustc_ast::tokenstream::TokenStream;
@@ -12,15 +12,17 @@ use rustc_ast::{
     MetaItemKind, ModKind, NodeId, PatKind, StmtKind, TyKind, token,
 };
 use rustc_ast_pretty::pprust;
-use rustc_attr_parsing::{EvalConfigResult, ShouldEmit};
+use rustc_attr_parsing::{AttributeParser, Early, EvalConfigResult, ShouldEmit, validate_attr};
 use rustc_data_structures::flat_map_in_place::FlatMapInPlace;
+use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_errors::PResult;
 use rustc_feature::Features;
+use rustc_hir::Target;
+use rustc_hir::def::MacroKinds;
 use rustc_parse::parser::{
     AttemptLocalParseRecovery, CommaRecoveryMode, ForceCollect, Parser, RecoverColon, RecoverComma,
     token_descr,
 };
-use rustc_parse::validate_attr;
 use rustc_session::lint::BuiltinLintDiag;
 use rustc_session::lint::builtin::{UNUSED_ATTRIBUTES, UNUSED_DOC_COMMENTS};
 use rustc_session::parse::feature_err;
@@ -565,6 +567,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                                 .map(|DeriveResolution { path, item, exts: _, is_const }| {
                                     // FIXME: Consider using the derive resolutions (`_exts`)
                                     // instead of enqueuing the derives to be resolved again later.
+                                    // Note that this can result in duplicate diagnostics.
                                     let expn_id = LocalExpnId::fresh_empty();
                                     derive_invocations.push((
                                         Invocation {
@@ -736,8 +739,8 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
 
         let (fragment_kind, span) = (invoc.fragment_kind, invoc.span());
         ExpandResult::Ready(match invoc.kind {
-            InvocationKind::Bang { mac, span } => match ext {
-                SyntaxExtensionKind::Bang(expander) => {
+            InvocationKind::Bang { mac, span } => {
+                if let SyntaxExtensionKind::Bang(expander) = ext {
                     match expander.expand(self.cx, span, mac.args.tokens.clone()) {
                         Ok(tok_result) => {
                             let fragment =
@@ -755,8 +758,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                         }
                         Err(guar) => return ExpandResult::Ready(fragment_kind.dummy(span, guar)),
                     }
-                }
-                SyntaxExtensionKind::LegacyBang(expander) => {
+                } else if let Some(expander) = ext.as_legacy_bang() {
                     let tok_result = match expander.expand(self.cx, span, mac.args.tokens.clone()) {
                         ExpandResult::Ready(tok_result) => tok_result,
                         ExpandResult::Retry(_) => {
@@ -776,11 +778,12 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                         let guar = self.error_wrong_fragment_kind(fragment_kind, &mac, span);
                         fragment_kind.dummy(span, guar)
                     }
+                } else {
+                    unreachable!();
                 }
-                _ => unreachable!(),
-            },
-            InvocationKind::Attr { attr, pos, mut item, derives } => match ext {
-                SyntaxExtensionKind::Attr(expander) => {
+            }
+            InvocationKind::Attr { attr, pos, mut item, derives } => {
+                if let Some(expander) = ext.as_attr() {
                     self.gate_proc_macro_input(&item);
                     self.gate_proc_macro_attr_item(span, &item);
                     let tokens = match &item {
@@ -799,7 +802,8 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                                     ItemKind::Mod(
                                         _,
                                         _,
-                                        ModKind::Unloaded | ModKind::Loaded(_, Inline::No, _, _),
+                                        ModKind::Unloaded
+                                            | ModKind::Loaded(_, Inline::No { .. }, _),
                                     )
                                 ) =>
                         {
@@ -835,8 +839,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                         }
                         Err(guar) => return ExpandResult::Ready(fragment_kind.dummy(span, guar)),
                     }
-                }
-                SyntaxExtensionKind::LegacyAttr(expander) => {
+                } else if let SyntaxExtensionKind::LegacyAttr(expander) = ext {
                     match validate_attr::parse_meta(&self.cx.sess.psess, &attr) {
                         Ok(meta) => {
                             let item_clone = macro_stats.then(|| item.clone());
@@ -878,15 +881,15 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                             fragment_kind.expect_from_annotatables(iter::once(item))
                         }
                     }
-                }
-                SyntaxExtensionKind::NonMacroAttr => {
+                } else if let SyntaxExtensionKind::NonMacroAttr = ext {
                     // `-Zmacro-stats` ignores these because they don't do any real expansion.
                     self.cx.expanded_inert_attrs.mark(&attr);
                     item.visit_attrs(|attrs| attrs.insert(pos, attr));
                     fragment_kind.expect_from_annotatables(iter::once(item))
+                } else {
+                    unreachable!();
                 }
-                _ => unreachable!(),
-            },
+            }
             InvocationKind::Derive { path, item, is_const } => match ext {
                 SyntaxExtensionKind::Derive(expander)
                 | SyntaxExtensionKind::LegacyDerive(expander) => {
@@ -923,6 +926,35 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                     }
                     fragment
                 }
+                SyntaxExtensionKind::MacroRules(expander)
+                    if expander.kinds().contains(MacroKinds::DERIVE) =>
+                {
+                    if is_const {
+                        let guar = self
+                            .cx
+                            .dcx()
+                            .span_err(span, "macro `derive` does not support const derives");
+                        return ExpandResult::Ready(fragment_kind.dummy(span, guar));
+                    }
+                    let body = item.to_tokens();
+                    match expander.expand_derive(self.cx, span, &body) {
+                        Ok(tok_result) => {
+                            let fragment =
+                                self.parse_ast_fragment(tok_result, fragment_kind, &path, span);
+                            if macro_stats {
+                                update_derive_macro_stats(
+                                    self.cx,
+                                    fragment_kind,
+                                    span,
+                                    &path,
+                                    &fragment,
+                                );
+                            }
+                            fragment
+                        }
+                        Err(guar) => return ExpandResult::Ready(fragment_kind.dummy(span, guar)),
+                    }
+                }
                 _ => unreachable!(),
             },
             InvocationKind::GlobDelegation { item, of_trait } => {
@@ -1005,7 +1037,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             fn visit_item(&mut self, item: &'ast ast::Item) {
                 match &item.kind {
                     ItemKind::Mod(_, _, mod_kind)
-                        if !matches!(mod_kind, ModKind::Loaded(_, Inline::Yes, _, _)) =>
+                        if !matches!(mod_kind, ModKind::Loaded(_, Inline::Yes, _)) =>
                     {
                         feature_err(
                             self.sess,
@@ -1316,7 +1348,7 @@ impl InvocationCollectorNode for Box<ast::Item> {
         let ItemKind::Mod(_, ident, ref mut mod_kind) = node.kind else { unreachable!() };
         let ecx = &mut collector.cx;
         let (file_path, dir_path, dir_ownership) = match mod_kind {
-            ModKind::Loaded(_, inline, _, _) => {
+            ModKind::Loaded(_, inline, _) => {
                 // Inline `mod foo { ... }`, but we still need to push directories.
                 let (dir_path, dir_ownership) = mod_dir_path(
                     ecx.sess,
@@ -1330,7 +1362,7 @@ impl InvocationCollectorNode for Box<ast::Item> {
                 // This lets `parse_external_mod` catch cycles if it's self-referential.
                 let file_path = match inline {
                     Inline::Yes => None,
-                    Inline::No => mod_file_path_from_attr(ecx.sess, &attrs, &dir_path),
+                    Inline::No { .. } => mod_file_path_from_attr(ecx.sess, &attrs, &dir_path),
                 };
                 node.attrs = attrs;
                 (file_path, dir_path, dir_ownership)
@@ -1366,7 +1398,7 @@ impl InvocationCollectorNode for Box<ast::Item> {
                     );
                 }
 
-                *mod_kind = ModKind::Loaded(items, Inline::No, spans, had_parse_error);
+                *mod_kind = ModKind::Loaded(items, Inline::No { had_parse_error }, spans);
                 node.attrs = attrs;
                 if node.attrs.len() > old_attrs_len {
                     // If we loaded an out-of-line module and added some inner attributes,
@@ -2127,6 +2159,16 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
                 attr,
                 self.cx.current_expansion.lint_node_id,
             );
+            AttributeParser::parse_limited_all(
+                self.cx.sess,
+                slice::from_ref(attr),
+                None,
+                Target::MacroCall,
+                call.span(),
+                self.cx.current_expansion.lint_node_id,
+                Some(self.cx.ecfg.features),
+                ShouldEmit::ErrorsAndLints,
+            );
 
             let current_span = if let Some(sp) = span { sp.to(attr.span) } else { attr.span };
             span = Some(current_span);
@@ -2142,7 +2184,9 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
                     self.cx.current_expansion.lint_node_id,
                     BuiltinLintDiag::UnusedDocComment(attr.span),
                 );
-            } else if rustc_attr_parsing::is_builtin_attr(attr) {
+            } else if rustc_attr_parsing::is_builtin_attr(attr)
+                && !AttributeParser::<Early>::is_parsed_attribute(&attr.path())
+            {
                 let attr_name = attr.ident().unwrap().name;
                 // `#[cfg]` and `#[cfg_attr]` are special - they are
                 // eagerly evaluated.
@@ -2155,6 +2199,7 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
                             attr_name,
                             macro_name: pprust::path_to_string(&call.path),
                             invoc_span: call.path.span,
+                            attr_span: attr.span,
                         },
                     );
                 }
@@ -2437,7 +2482,7 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
         if let Some(attr) = node.attrs.first() {
             self.cfg().maybe_emit_expr_attr_err(attr);
         }
-        self.visit_node(node)
+        ensure_sufficient_stack(|| self.visit_node(node))
     }
 
     fn visit_method_receiver_expr(&mut self, node: &mut ast::Expr) {
diff --git a/compiler/rustc_expand/src/mbe/diagnostics.rs b/compiler/rustc_expand/src/mbe/diagnostics.rs
index 5b9d56ee2bc..f5edaf50edd 100644
--- a/compiler/rustc_expand/src/mbe/diagnostics.rs
+++ b/compiler/rustc_expand/src/mbe/diagnostics.rs
@@ -14,14 +14,22 @@ use super::macro_rules::{MacroRule, NoopTracker, parser_from_cx};
 use crate::expand::{AstFragmentKind, parse_ast_fragment};
 use crate::mbe::macro_parser::ParseResult::*;
 use crate::mbe::macro_parser::{MatcherLoc, NamedParseResult, TtParser};
-use crate::mbe::macro_rules::{Tracker, try_match_macro, try_match_macro_attr};
+use crate::mbe::macro_rules::{
+    Tracker, try_match_macro, try_match_macro_attr, try_match_macro_derive,
+};
+
+pub(super) enum FailedMacro<'a> {
+    Func,
+    Attr(&'a TokenStream),
+    Derive,
+}
 
 pub(super) fn failed_to_match_macro(
     psess: &ParseSess,
     sp: Span,
     def_span: Span,
     name: Ident,
-    attr_args: Option<&TokenStream>,
+    args: FailedMacro<'_>,
     body: &TokenStream,
     rules: &[MacroRule],
 ) -> (Span, ErrorGuaranteed) {
@@ -36,10 +44,12 @@ pub(super) fn failed_to_match_macro(
     // diagnostics.
     let mut tracker = CollectTrackerAndEmitter::new(psess.dcx(), sp);
 
-    let try_success_result = if let Some(attr_args) = attr_args {
-        try_match_macro_attr(psess, name, attr_args, body, rules, &mut tracker)
-    } else {
-        try_match_macro(psess, name, body, rules, &mut tracker)
+    let try_success_result = match args {
+        FailedMacro::Func => try_match_macro(psess, name, body, rules, &mut tracker),
+        FailedMacro::Attr(attr_args) => {
+            try_match_macro_attr(psess, name, attr_args, body, rules, &mut tracker)
+        }
+        FailedMacro::Derive => try_match_macro_derive(psess, name, body, rules, &mut tracker),
     };
 
     if try_success_result.is_ok() {
@@ -58,18 +68,6 @@ pub(super) fn failed_to_match_macro(
 
     let Some(BestFailure { token, msg: label, remaining_matcher, .. }) = tracker.best_failure
     else {
-        // FIXME: we should report this at macro resolution time, as we do for
-        // `resolve_macro_cannot_use_as_attr`. We can do that once we track multiple macro kinds for a
-        // Def.
-        if attr_args.is_none() && !rules.iter().any(|rule| matches!(rule, MacroRule::Func { .. })) {
-            let msg = format!("macro has no rules for function-like invocation `{name}!`");
-            let mut err = psess.dcx().struct_span_err(sp, msg);
-            if !def_head_span.is_dummy() {
-                let msg = "this macro has no rules for function-like invocation";
-                err.span_label(def_head_span, msg);
-            }
-            return (sp, err.emit());
-        }
         return (sp, psess.dcx().span_delayed_bug(sp, "failed to match a macro"));
     };
 
@@ -102,7 +100,7 @@ pub(super) fn failed_to_match_macro(
     }
 
     // Check whether there's a missing comma in this macro call, like `println!("{}" a);`
-    if attr_args.is_none()
+    if let FailedMacro::Func = args
         && let Some((body, comma_span)) = body.add_comma()
     {
         for rule in rules {
diff --git a/compiler/rustc_expand/src/mbe/macro_check.rs b/compiler/rustc_expand/src/mbe/macro_check.rs
index 25987a50366..faeae1f494e 100644
--- a/compiler/rustc_expand/src/mbe/macro_check.rs
+++ b/compiler/rustc_expand/src/mbe/macro_check.rs
@@ -357,10 +357,10 @@ enum NestedMacroState {
     /// The token `macro_rules` was processed.
     MacroRules,
     /// The tokens `macro_rules!` were processed.
-    MacroRulesNot,
+    MacroRulesBang,
     /// The tokens `macro_rules!` followed by a name were processed. The name may be either directly
     /// an identifier or a meta-variable (that hopefully would be instantiated by an identifier).
-    MacroRulesNotName,
+    MacroRulesBangName,
     /// The keyword `macro` was processed.
     Macro,
     /// The keyword `macro` followed by a name was processed.
@@ -408,24 +408,24 @@ fn check_nested_occurrences(
                 NestedMacroState::MacroRules,
                 &TokenTree::Token(Token { kind: TokenKind::Bang, .. }),
             ) => {
-                state = NestedMacroState::MacroRulesNot;
+                state = NestedMacroState::MacroRulesBang;
             }
             (
-                NestedMacroState::MacroRulesNot,
+                NestedMacroState::MacroRulesBang,
                 &TokenTree::Token(Token { kind: TokenKind::Ident(..), .. }),
             ) => {
-                state = NestedMacroState::MacroRulesNotName;
+                state = NestedMacroState::MacroRulesBangName;
             }
-            (NestedMacroState::MacroRulesNot, &TokenTree::MetaVar(..)) => {
-                state = NestedMacroState::MacroRulesNotName;
+            (NestedMacroState::MacroRulesBang, &TokenTree::MetaVar(..)) => {
+                state = NestedMacroState::MacroRulesBangName;
                 // We check that the meta-variable is correctly used.
                 check_occurrences(psess, node_id, tt, macros, binders, ops, guar);
             }
-            (NestedMacroState::MacroRulesNotName, TokenTree::Delimited(.., del))
+            (NestedMacroState::MacroRulesBangName, TokenTree::Delimited(.., del))
             | (NestedMacroState::MacroName, TokenTree::Delimited(.., del))
                 if del.delim == Delimiter::Brace =>
             {
-                let macro_rules = state == NestedMacroState::MacroRulesNotName;
+                let macro_rules = state == NestedMacroState::MacroRulesBangName;
                 state = NestedMacroState::Empty;
                 let rest =
                     check_nested_macro(psess, node_id, macro_rules, &del.tts, &nested_macros, guar);
diff --git a/compiler/rustc_expand/src/mbe/macro_rules.rs b/compiler/rustc_expand/src/mbe/macro_rules.rs
index 08b0efb74a0..8b43f852b26 100644
--- a/compiler/rustc_expand/src/mbe/macro_rules.rs
+++ b/compiler/rustc_expand/src/mbe/macro_rules.rs
@@ -15,6 +15,7 @@ use rustc_errors::{Applicability, Diag, ErrorGuaranteed, MultiSpan};
 use rustc_feature::Features;
 use rustc_hir as hir;
 use rustc_hir::attrs::AttributeKind;
+use rustc_hir::def::MacroKinds;
 use rustc_hir::find_attr;
 use rustc_lint_defs::BuiltinLintDiag;
 use rustc_lint_defs::builtin::{
@@ -26,10 +27,10 @@ use rustc_session::Session;
 use rustc_session::parse::{ParseSess, feature_err};
 use rustc_span::edition::Edition;
 use rustc_span::hygiene::Transparency;
-use rustc_span::{Ident, Span, kw, sym};
+use rustc_span::{Ident, Span, Symbol, kw, sym};
 use tracing::{debug, instrument, trace, trace_span};
 
-use super::diagnostics::failed_to_match_macro;
+use super::diagnostics::{FailedMacro, failed_to_match_macro};
 use super::macro_parser::{NamedMatches, NamedParseResult};
 use super::{SequenceRepetition, diagnostics};
 use crate::base::{
@@ -137,6 +138,8 @@ pub(super) enum MacroRule {
         body_span: Span,
         rhs: mbe::TokenTree,
     },
+    /// A derive rule, for use with `#[m]`
+    Derive { body: Vec<MatcherLoc>, body_span: Span, rhs: mbe::TokenTree },
 }
 
 pub struct MacroRulesMacroExpander {
@@ -144,6 +147,7 @@ pub struct MacroRulesMacroExpander {
     name: Ident,
     span: Span,
     transparency: Transparency,
+    kinds: MacroKinds,
     rules: Vec<MacroRule>,
 }
 
@@ -155,9 +159,71 @@ impl MacroRulesMacroExpander {
             MacroRule::Attr { args_span, body_span, ref rhs, .. } => {
                 (MultiSpan::from_spans(vec![args_span, body_span]), rhs)
             }
+            MacroRule::Derive { body_span, ref rhs, .. } => (MultiSpan::from_span(body_span), rhs),
         };
         if has_compile_error_macro(rhs) { None } else { Some((&self.name, span)) }
     }
+
+    pub fn kinds(&self) -> MacroKinds {
+        self.kinds
+    }
+
+    pub fn expand_derive(
+        &self,
+        cx: &mut ExtCtxt<'_>,
+        sp: Span,
+        body: &TokenStream,
+    ) -> Result<TokenStream, ErrorGuaranteed> {
+        // This is similar to `expand_macro`, but they have very different signatures, and will
+        // diverge further once derives support arguments.
+        let Self { name, ref rules, node_id, .. } = *self;
+        let psess = &cx.sess.psess;
+
+        if cx.trace_macros() {
+            let msg = format!("expanding `#[derive({name})] {}`", pprust::tts_to_string(body));
+            trace_macros_note(&mut cx.expansions, sp, msg);
+        }
+
+        match try_match_macro_derive(psess, name, body, rules, &mut NoopTracker) {
+            Ok((rule_index, rule, named_matches)) => {
+                let MacroRule::Derive { rhs, .. } = rule else {
+                    panic!("try_match_macro_derive returned non-derive rule");
+                };
+                let mbe::TokenTree::Delimited(rhs_span, _, rhs) = rhs else {
+                    cx.dcx().span_bug(sp, "malformed macro derive rhs");
+                };
+
+                let id = cx.current_expansion.id;
+                let tts = transcribe(psess, &named_matches, rhs, *rhs_span, self.transparency, id)
+                    .map_err(|e| e.emit())?;
+
+                if cx.trace_macros() {
+                    let msg = format!("to `{}`", pprust::tts_to_string(&tts));
+                    trace_macros_note(&mut cx.expansions, sp, msg);
+                }
+
+                if is_defined_in_current_crate(node_id) {
+                    cx.resolver.record_macro_rule_usage(node_id, rule_index);
+                }
+
+                Ok(tts)
+            }
+            Err(CanRetry::No(guar)) => Err(guar),
+            Err(CanRetry::Yes) => {
+                let (_, guar) = failed_to_match_macro(
+                    cx.psess(),
+                    sp,
+                    self.span,
+                    name,
+                    FailedMacro::Derive,
+                    body,
+                    rules,
+                );
+                cx.macro_error_and_trace_macros_diag();
+                Err(guar)
+            }
+        }
+    }
 }
 
 impl TTMacroExpander for MacroRulesMacroExpander {
@@ -319,8 +385,15 @@ fn expand_macro<'cx>(
         }
         Err(CanRetry::Yes) => {
             // Retry and emit a better error.
-            let (span, guar) =
-                failed_to_match_macro(cx.psess(), sp, def_span, name, None, &arg, rules);
+            let (span, guar) = failed_to_match_macro(
+                cx.psess(),
+                sp,
+                def_span,
+                name,
+                FailedMacro::Func,
+                &arg,
+                rules,
+            );
             cx.macro_error_and_trace_macros_diag();
             DummyResult::any(span, guar)
         }
@@ -382,8 +455,15 @@ fn expand_macro_attr(
         Err(CanRetry::No(guar)) => Err(guar),
         Err(CanRetry::Yes) => {
             // Retry and emit a better error.
-            let (_, guar) =
-                failed_to_match_macro(cx.psess(), sp, def_span, name, Some(&args), &body, rules);
+            let (_, guar) = failed_to_match_macro(
+                cx.psess(),
+                sp,
+                def_span,
+                name,
+                FailedMacro::Attr(&args),
+                &body,
+                rules,
+            );
             cx.trace_macros_diag();
             Err(guar)
         }
@@ -516,6 +596,7 @@ pub(super) fn try_match_macro_attr<'matcher, T: Tracker<'matcher>>(
         match result {
             Success(body_named_matches) => {
                 psess.gated_spans.merge(gated_spans_snapshot);
+                #[allow(rustc::potential_query_instability)]
                 named_matches.extend(body_named_matches);
                 return Ok((i, rule, named_matches));
             }
@@ -530,6 +611,44 @@ pub(super) fn try_match_macro_attr<'matcher, T: Tracker<'matcher>>(
     Err(CanRetry::Yes)
 }
 
+/// Try expanding the macro derive. Returns the index of the successful arm and its
+/// named_matches if it was successful, and nothing if it failed. On failure, it's the caller's job
+/// to use `track` accordingly to record all errors correctly.
+#[instrument(level = "debug", skip(psess, body, rules, track), fields(tracking = %T::description()))]
+pub(super) fn try_match_macro_derive<'matcher, T: Tracker<'matcher>>(
+    psess: &ParseSess,
+    name: Ident,
+    body: &TokenStream,
+    rules: &'matcher [MacroRule],
+    track: &mut T,
+) -> Result<(usize, &'matcher MacroRule, NamedMatches), CanRetry> {
+    // This uses the same strategy as `try_match_macro`
+    let body_parser = parser_from_cx(psess, body.clone(), T::recovery());
+    let mut tt_parser = TtParser::new(name);
+    for (i, rule) in rules.iter().enumerate() {
+        let MacroRule::Derive { body, .. } = rule else { continue };
+
+        let mut gated_spans_snapshot = mem::take(&mut *psess.gated_spans.spans.borrow_mut());
+
+        let result = tt_parser.parse_tt(&mut Cow::Borrowed(&body_parser), body, track);
+        track.after_arm(true, &result);
+
+        match result {
+            Success(named_matches) => {
+                psess.gated_spans.merge(gated_spans_snapshot);
+                return Ok((i, rule, named_matches));
+            }
+            Failure(_) => {
+                mem::swap(&mut gated_spans_snapshot, &mut psess.gated_spans.spans.borrow_mut())
+            }
+            Error(_, _) => return Err(CanRetry::Yes),
+            ErrorReported(guar) => return Err(CanRetry::No(guar)),
+        }
+    }
+
+    Err(CanRetry::Yes)
+}
+
 /// Converts a macro item into a syntax extension.
 pub fn compile_declarative_macro(
     sess: &Session,
@@ -540,13 +659,13 @@ pub fn compile_declarative_macro(
     span: Span,
     node_id: NodeId,
     edition: Edition,
-) -> (SyntaxExtension, Option<Arc<SyntaxExtension>>, usize) {
+) -> (SyntaxExtension, usize) {
     let mk_syn_ext = |kind| {
         let is_local = is_defined_in_current_crate(node_id);
         SyntaxExtension::new(sess, kind, span, Vec::new(), edition, ident.name, attrs, is_local)
     };
-    let mk_bang_ext = |expander| mk_syn_ext(SyntaxExtensionKind::LegacyBang(expander));
-    let dummy_syn_ext = |guar| (mk_bang_ext(Arc::new(DummyExpander(guar))), None, 0);
+    let dummy_syn_ext =
+        |guar| (mk_syn_ext(SyntaxExtensionKind::LegacyBang(Arc::new(DummyExpander(guar)))), 0);
 
     let macro_rules = macro_def.macro_rules;
     let exp_sep = if macro_rules { exp!(Semi) } else { exp!(Comma) };
@@ -559,12 +678,12 @@ pub fn compile_declarative_macro(
     let mut guar = None;
     let mut check_emission = |ret: Result<(), ErrorGuaranteed>| guar = guar.or(ret.err());
 
-    let mut has_attr_rules = false;
+    let mut kinds = MacroKinds::empty();
     let mut rules = Vec::new();
 
     while p.token != token::Eof {
-        let args = if p.eat_keyword_noexpect(sym::attr) {
-            has_attr_rules = true;
+        let (args, is_derive) = if p.eat_keyword_noexpect(sym::attr) {
+            kinds |= MacroKinds::ATTR;
             if !features.macro_attr() {
                 feature_err(sess, sym::macro_attr, span, "`macro_rules!` attributes are unstable")
                     .emit();
@@ -573,15 +692,46 @@ pub fn compile_declarative_macro(
                 return dummy_syn_ext(guar);
             }
             let args = p.parse_token_tree();
-            check_args_parens(sess, &args);
+            check_args_parens(sess, sym::attr, &args);
             let args = parse_one_tt(args, RulePart::Pattern, sess, node_id, features, edition);
             check_emission(check_lhs(sess, node_id, &args));
             if let Some(guar) = check_no_eof(sess, &p, "expected macro attr body") {
                 return dummy_syn_ext(guar);
             }
-            Some(args)
+            (Some(args), false)
+        } else if p.eat_keyword_noexpect(sym::derive) {
+            kinds |= MacroKinds::DERIVE;
+            let derive_keyword_span = p.prev_token.span;
+            if !features.macro_derive() {
+                feature_err(sess, sym::macro_attr, span, "`macro_rules!` derives are unstable")
+                    .emit();
+            }
+            if let Some(guar) = check_no_eof(sess, &p, "expected `()` after `derive`") {
+                return dummy_syn_ext(guar);
+            }
+            let args = p.parse_token_tree();
+            check_args_parens(sess, sym::derive, &args);
+            let args_empty_result = check_args_empty(sess, &args);
+            let args_not_empty = args_empty_result.is_err();
+            check_emission(args_empty_result);
+            if let Some(guar) = check_no_eof(sess, &p, "expected macro derive body") {
+                return dummy_syn_ext(guar);
+            }
+            // If the user has `=>` right after the `()`, they might have forgotten the empty
+            // parentheses.
+            if p.token == token::FatArrow {
+                let mut err = sess
+                    .dcx()
+                    .struct_span_err(p.token.span, "expected macro derive body, got `=>`");
+                if args_not_empty {
+                    err.span_label(derive_keyword_span, "need `()` after this `derive`");
+                }
+                return dummy_syn_ext(err.emit());
+            }
+            (None, true)
         } else {
-            None
+            kinds |= MacroKinds::BANG;
+            (None, false)
         };
         let lhs_tt = p.parse_token_tree();
         let lhs_tt = parse_one_tt(lhs_tt, RulePart::Pattern, sess, node_id, features, edition);
@@ -612,6 +762,8 @@ pub fn compile_declarative_macro(
             let args = mbe::macro_parser::compute_locs(&delimited.tts);
             let body_span = lhs_span;
             rules.push(MacroRule::Attr { args, args_span, body: lhs, body_span, rhs: rhs_tt });
+        } else if is_derive {
+            rules.push(MacroRule::Derive { body: lhs, body_span: lhs_span, rhs: rhs_tt });
         } else {
             rules.push(MacroRule::Func { lhs, lhs_span, rhs: rhs_tt });
         }
@@ -627,6 +779,7 @@ pub fn compile_declarative_macro(
         let guar = sess.dcx().span_err(span, "macros must contain at least one rule");
         return dummy_syn_ext(guar);
     }
+    assert!(!kinds.is_empty());
 
     let transparency = find_attr!(attrs, AttributeKind::MacroTransparency(x) => *x)
         .unwrap_or(Transparency::fallback(macro_rules));
@@ -640,12 +793,8 @@ pub fn compile_declarative_macro(
     // Return the number of rules for unused rule linting, if this is a local macro.
     let nrules = if is_defined_in_current_crate(node_id) { rules.len() } else { 0 };
 
-    let exp = Arc::new(MacroRulesMacroExpander { name: ident, span, node_id, transparency, rules });
-    let opt_attr_ext = has_attr_rules.then(|| {
-        let exp = Arc::clone(&exp);
-        Arc::new(mk_syn_ext(SyntaxExtensionKind::Attr(exp)))
-    });
-    (mk_bang_ext(exp), opt_attr_ext, nrules)
+    let exp = MacroRulesMacroExpander { name: ident, kinds, span, node_id, transparency, rules };
+    (mk_syn_ext(SyntaxExtensionKind::MacroRules(Arc::new(exp))), nrules)
 }
 
 fn check_no_eof(sess: &Session, p: &Parser<'_>, msg: &'static str) -> Option<ErrorGuaranteed> {
@@ -661,7 +810,7 @@ fn check_no_eof(sess: &Session, p: &Parser<'_>, msg: &'static str) -> Option<Err
     None
 }
 
-fn check_args_parens(sess: &Session, args: &tokenstream::TokenTree) {
+fn check_args_parens(sess: &Session, rule_kw: Symbol, args: &tokenstream::TokenTree) {
     // This does not handle the non-delimited case; that gets handled separately by `check_lhs`.
     if let tokenstream::TokenTree::Delimited(dspan, _, delim, _) = args
         && *delim != Delimiter::Parenthesis
@@ -669,10 +818,21 @@ fn check_args_parens(sess: &Session, args: &tokenstream::TokenTree) {
         sess.dcx().emit_err(errors::MacroArgsBadDelim {
             span: dspan.entire(),
             sugg: errors::MacroArgsBadDelimSugg { open: dspan.open, close: dspan.close },
+            rule_kw,
         });
     }
 }
 
+fn check_args_empty(sess: &Session, args: &tokenstream::TokenTree) -> Result<(), ErrorGuaranteed> {
+    match args {
+        tokenstream::TokenTree::Delimited(.., delimited) if delimited.is_empty() => Ok(()),
+        _ => {
+            let msg = "`derive` rules do not accept arguments; `derive` must be followed by `()`";
+            Err(sess.dcx().span_err(args.span(), msg))
+        }
+    }
+}
+
 fn check_lhs(sess: &Session, node_id: NodeId, lhs: &mbe::TokenTree) -> Result<(), ErrorGuaranteed> {
     let e1 = check_lhs_nt_follows(sess, node_id, lhs);
     let e2 = check_lhs_no_empty_seq(sess, slice::from_ref(lhs));
diff --git a/compiler/rustc_expand/src/module.rs b/compiler/rustc_expand/src/module.rs
index 662c67f2d3f..19f3cdbc549 100644
--- a/compiler/rustc_expand/src/module.rs
+++ b/compiler/rustc_expand/src/module.rs
@@ -2,8 +2,9 @@ use std::iter::once;
 use std::path::{self, Path, PathBuf};
 
 use rustc_ast::{AttrVec, Attribute, Inline, Item, ModSpans};
+use rustc_attr_parsing::validate_attr;
 use rustc_errors::{Diag, ErrorGuaranteed};
-use rustc_parse::{exp, new_parser_from_file, unwrap_or_emit_fatal, validate_attr};
+use rustc_parse::{exp, new_parser_from_file, unwrap_or_emit_fatal};
 use rustc_session::Session;
 use rustc_session::parse::ParseSess;
 use rustc_span::{Ident, Span, sym};
@@ -120,7 +121,7 @@ pub(crate) fn mod_dir_path(
 
             (dir_path, dir_ownership)
         }
-        Inline::No => {
+        Inline::No { .. } => {
             // FIXME: This is a subset of `parse_external_mod` without actual parsing,
             // check whether the logic for unloaded, loaded and inline modules can be unified.
             let file_path = mod_file_path(sess, ident, attrs, &module.dir_path, dir_ownership)
diff --git a/compiler/rustc_expand/src/proc_macro_server.rs b/compiler/rustc_expand/src/proc_macro_server.rs
index fd71f2ce948..5b1d3d6d35b 100644
--- a/compiler/rustc_expand/src/proc_macro_server.rs
+++ b/compiler/rustc_expand/src/proc_macro_server.rs
@@ -250,12 +250,14 @@ impl FromInternal<(TokenStream, &mut Rustc<'_, '_>)> for Vec<TokenTree<TokenStre
                 Question => op("?"),
                 SingleQuote => op("'"),
 
-                Ident(sym, is_raw) => {
-                    trees.push(TokenTree::Ident(Ident { sym, is_raw: is_raw.into(), span }))
-                }
+                Ident(sym, is_raw) => trees.push(TokenTree::Ident(Ident {
+                    sym,
+                    is_raw: matches!(is_raw, IdentIsRaw::Yes),
+                    span,
+                })),
                 NtIdent(ident, is_raw) => trees.push(TokenTree::Ident(Ident {
                     sym: ident.name,
-                    is_raw: is_raw.into(),
+                    is_raw: matches!(is_raw, IdentIsRaw::Yes),
                     span: ident.span,
                 })),
 
@@ -263,7 +265,11 @@ impl FromInternal<(TokenStream, &mut Rustc<'_, '_>)> for Vec<TokenTree<TokenStre
                     let ident = rustc_span::Ident::new(name, span).without_first_quote();
                     trees.extend([
                         TokenTree::Punct(Punct { ch: b'\'', joint: true, span }),
-                        TokenTree::Ident(Ident { sym: ident.name, is_raw: is_raw.into(), span }),
+                        TokenTree::Ident(Ident {
+                            sym: ident.name,
+                            is_raw: matches!(is_raw, IdentIsRaw::Yes),
+                            span,
+                        }),
                     ]);
                 }
                 NtLifetime(ident, is_raw) => {
diff --git a/compiler/rustc_feature/src/accepted.rs b/compiler/rustc_feature/src/accepted.rs
index 83be3241b12..9fe55216f93 100644
--- a/compiler/rustc_feature/src/accepted.rs
+++ b/compiler/rustc_feature/src/accepted.rs
@@ -396,6 +396,8 @@ declare_features! (
     (accepted, slice_patterns, "1.42.0", Some(62254)),
     /// Allows use of `&foo[a..b]` as a slicing syntax.
     (accepted, slicing_syntax, "1.0.0", None),
+    /// Allows use of `sse4a` target feature.
+    (accepted, sse4a_target_feature, "CURRENT_RUSTC_VERSION", Some(44839)),
     /// Allows elision of `'static` lifetimes in `static`s and `const`s.
     (accepted, static_in_const, "1.17.0", Some(35897)),
     /// Allows the definition recursive static items.
@@ -408,6 +410,8 @@ declare_features! (
     (accepted, target_feature, "1.27.0", None),
     /// Allows the use of `#[target_feature]` on safe functions.
     (accepted, target_feature_11, "1.86.0", Some(69098)),
+    /// Allows use of `tbm` target feature.
+    (accepted, tbm_target_feature, "CURRENT_RUSTC_VERSION", Some(44839)),
     /// Allows `fn main()` with return types which implements `Termination` (RFC 1937).
     (accepted, termination_trait, "1.26.0", Some(43301)),
     /// Allows `#[test]` functions where the return type implements `Termination` (RFC 1937).
diff --git a/compiler/rustc_feature/src/builtin_attrs.rs b/compiler/rustc_feature/src/builtin_attrs.rs
index ab6b8f92802..e81003b1897 100644
--- a/compiler/rustc_feature/src/builtin_attrs.rs
+++ b/compiler/rustc_feature/src/builtin_attrs.rs
@@ -6,6 +6,7 @@ use AttributeDuplicates::*;
 use AttributeGate::*;
 use AttributeType::*;
 use rustc_data_structures::fx::FxHashMap;
+use rustc_hir::AttrStyle;
 use rustc_hir::attrs::EncodeCrossCrate;
 use rustc_span::edition::Edition;
 use rustc_span::{Symbol, sym};
@@ -132,9 +133,12 @@ pub struct AttributeTemplate {
 }
 
 impl AttributeTemplate {
-    pub fn suggestions(&self, inner: bool, name: impl std::fmt::Display) -> Vec<String> {
+    pub fn suggestions(&self, style: AttrStyle, name: impl std::fmt::Display) -> Vec<String> {
         let mut suggestions = vec![];
-        let inner = if inner { "!" } else { "" };
+        let inner = match style {
+            AttrStyle::Outer => "",
+            AttrStyle::Inner => "!",
+        };
         if self.word {
             suggestions.push(format!("#{inner}[{name}]"));
         }
@@ -741,9 +745,12 @@ pub static BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         ErrorPreceding, EncodeCrossCrate::No
     ),
     gated!(
-        no_sanitize, Normal,
-        template!(List: &["address, kcfi, memory, thread"]), DuplicatesOk,
-        EncodeCrossCrate::No, experimental!(no_sanitize)
+        unsafe force_target_feature, Normal, template!(List: &[r#"enable = "name""#]),
+        DuplicatesOk, EncodeCrossCrate::No, effective_target_features, experimental!(force_target_feature)
+    ),
+    gated!(
+        sanitize, Normal, template!(List: &[r#"address = "on|off""#, r#"kernel_address = "on|off""#, r#"cfi = "on|off""#, r#"hwaddress = "on|off""#, r#"kcfi = "on|off""#, r#"memory = "on|off""#, r#"memtag = "on|off""#, r#"shadow_call_stack = "on|off""#, r#"thread = "on|off""#]), ErrorPreceding,
+        EncodeCrossCrate::No, sanitize, experimental!(sanitize),
     ),
     gated!(
         coverage, Normal, template!(OneOf: &[sym::off, sym::on]),
@@ -993,6 +1000,10 @@ pub static BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         rustc_allocator_zeroed, Normal, template!(Word), WarnFollowing,
         EncodeCrossCrate::No,
     ),
+    rustc_attr!(
+        rustc_allocator_zeroed_variant, Normal, template!(NameValueStr: "function"), ErrorPreceding,
+        EncodeCrossCrate::Yes,
+    ),
     gated!(
         default_lib_allocator, Normal, template!(Word), WarnFollowing,
         EncodeCrossCrate::No, allocator_internals, experimental!(default_lib_allocator),
@@ -1159,10 +1170,6 @@ pub static BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         EncodeCrossCrate::Yes, "`#[rustc_do_not_const_check]` skips const-check for this function's body",
     ),
     rustc_attr!(
-        rustc_const_panic_str, Normal, template!(Word), WarnFollowing,
-        EncodeCrossCrate::Yes, "`#[rustc_const_panic_str]` ensures the argument to this function is &&str during const-check",
-    ),
-    rustc_attr!(
         rustc_const_stable_indirect, Normal,
         template!(Word),
         WarnFollowing,
diff --git a/compiler/rustc_feature/src/removed.rs b/compiler/rustc_feature/src/removed.rs
index 04f261ada06..e37fc6b7bfc 100644
--- a/compiler/rustc_feature/src/removed.rs
+++ b/compiler/rustc_feature/src/removed.rs
@@ -190,6 +190,9 @@ declare_features! (
     (removed, no_coverage, "1.74.0", Some(84605), Some("renamed to `coverage_attribute`"), 114656),
     /// Allows `#[no_debug]`.
     (removed, no_debug, "1.43.0", Some(29721), Some("removed due to lack of demand"), 69667),
+    // Allows the use of `no_sanitize` attribute.
+    /// The feature was renamed to `sanitize` and the attribute to `#[sanitize(xyz = "on|off")]`
+    (removed, no_sanitize, "CURRENT_RUSTC_VERSION", Some(39699), Some(r#"renamed to sanitize(xyz = "on|off")"#), 142681),
     /// Note: this feature was previously recorded in a separate
     /// `STABLE_REMOVED` list because it, uniquely, was once stable but was
     /// then removed. But there was no utility storing it separately, so now
diff --git a/compiler/rustc_feature/src/unstable.rs b/compiler/rustc_feature/src/unstable.rs
index acc21f6c6d2..92b435b4b01 100644
--- a/compiler/rustc_feature/src/unstable.rs
+++ b/compiler/rustc_feature/src/unstable.rs
@@ -334,8 +334,6 @@ declare_features! (
     (unstable, rtm_target_feature, "1.35.0", Some(44839)),
     (unstable, s390x_target_feature, "1.82.0", Some(44839)),
     (unstable, sparc_target_feature, "1.84.0", Some(132783)),
-    (unstable, sse4a_target_feature, "1.27.0", Some(44839)),
-    (unstable, tbm_target_feature, "1.27.0", Some(44839)),
     (unstable, wasm_target_feature, "1.30.0", Some(44839)),
     (unstable, x87_target_feature, "1.85.0", Some(44839)),
     // !!!!    !!!!    !!!!    !!!!   !!!!    !!!!    !!!!    !!!!    !!!!    !!!!    !!!!
@@ -472,6 +470,8 @@ declare_features! (
     (unstable, deprecated_suggestion, "1.61.0", Some(94785)),
     /// Allows deref patterns.
     (incomplete, deref_patterns, "1.79.0", Some(87121)),
+    /// Allows deriving the From trait on single-field structs.
+    (unstable, derive_from, "CURRENT_RUSTC_VERSION", Some(144889)),
     /// Tells rustdoc to automatically generate `#[doc(cfg(...))]`.
     (unstable, doc_auto_cfg, "1.58.0", Some(43781)),
     /// Allows `#[doc(cfg(...))]`.
@@ -480,6 +480,8 @@ declare_features! (
     (unstable, doc_cfg_hide, "1.57.0", Some(43781)),
     /// Allows `#[doc(masked)]`.
     (unstable, doc_masked, "1.21.0", Some(44027)),
+    /// Allows features to allow target_feature to better interact with traits.
+    (incomplete, effective_target_features, "CURRENT_RUSTC_VERSION", Some(143352)),
     /// Allows the .use postfix syntax `x.use` and use closures `use |x| { ... }`
     (incomplete, ergonomic_clones, "1.87.0", Some(132290)),
     /// Allows exhaustive pattern matching on types that contain uninhabited types.
@@ -556,6 +558,8 @@ declare_features! (
     (incomplete, loop_match, "1.90.0", Some(132306)),
     /// Allow `macro_rules!` attribute rules
     (unstable, macro_attr, "CURRENT_RUSTC_VERSION", Some(83527)),
+    /// Allow `macro_rules!` derive rules
+    (unstable, macro_derive, "CURRENT_RUSTC_VERSION", Some(143549)),
     /// Give access to additional metadata about declarative macro meta-variables.
     (unstable, macro_metavar_expr, "1.61.0", Some(83527)),
     /// Provides a way to concatenate identifiers using metavariable expressions.
@@ -592,8 +596,6 @@ declare_features! (
     (unstable, new_range, "1.86.0", Some(123741)),
     /// Allows `#![no_core]`.
     (unstable, no_core, "1.3.0", Some(29639)),
-    /// Allows the use of `no_sanitize` attribute.
-    (unstable, no_sanitize, "1.42.0", Some(39699)),
     /// Allows using the `non_exhaustive_omitted_patterns` lint.
     (unstable, non_exhaustive_omitted_patterns_lint, "1.57.0", Some(89554)),
     /// Allows `for<T>` binders in where-clauses
@@ -614,6 +616,7 @@ declare_features! (
     (unstable, proc_macro_hygiene, "1.30.0", Some(54727)),
     /// Allows the use of raw-dylibs on ELF platforms
     (incomplete, raw_dylib_elf, "1.87.0", Some(135694)),
+    (unstable, reborrow, "CURRENT_RUSTC_VERSION", Some(145612)),
     /// Makes `&` and `&mut` patterns eat only one layer of references in Rust 2024.
     (incomplete, ref_pat_eat_one_layer_2024, "1.79.0", Some(123076)),
     /// Makes `&` and `&mut` patterns eat only one layer of references in Rust 2024—structural variant
@@ -626,6 +629,8 @@ declare_features! (
     (unstable, return_type_notation, "1.70.0", Some(109417)),
     /// Allows `extern "rust-cold"`.
     (unstable, rust_cold_cc, "1.63.0", Some(97544)),
+    /// Allows the use of the `sanitize` attribute.
+    (unstable, sanitize, "CURRENT_RUSTC_VERSION", Some(39699)),
     /// Allows the use of SIMD types in functions declared in `extern` blocks.
     (unstable, simd_ffi, "1.0.0", Some(27731)),
     /// Allows specialization of implementations (RFC 1210).
diff --git a/compiler/rustc_hir/Cargo.toml b/compiler/rustc_hir/Cargo.toml
index 539d2e6f0b1..ea72ed68c5e 100644
--- a/compiler/rustc_hir/Cargo.toml
+++ b/compiler/rustc_hir/Cargo.toml
@@ -5,19 +5,22 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
+bitflags.workspace = true
 odht = { version = "0.3.1", features = ["nightly"] }
 rustc_abi = { path = "../rustc_abi" }
 rustc_arena = { path = "../rustc_arena" }
 rustc_ast = { path = "../rustc_ast" }
 rustc_ast_pretty = { path = "../rustc_ast_pretty" }
 rustc_data_structures = { path = "../rustc_data_structures" }
+rustc_error_messages = { path = "../rustc_error_messages" }
 rustc_hashes = { path = "../rustc_hashes" }
+rustc_hir_id = { path = "../rustc_hir_id" }
 rustc_index = { path = "../rustc_index" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec = "0.2.12"
-tracing = "0.1"
+thin-vec.workspace = true
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_hir/src/attrs/data_structures.rs b/compiler/rustc_hir/src/attrs/data_structures.rs
index e02edf5fe24..dd5565d6f90 100644
--- a/compiler/rustc_hir/src/attrs/data_structures.rs
+++ b/compiler/rustc_hir/src/attrs/data_structures.rs
@@ -1,11 +1,16 @@
+use std::borrow::Cow;
+use std::path::PathBuf;
+
 pub use ReprAttr::*;
 use rustc_abi::Align;
 use rustc_ast::token::CommentKind;
 use rustc_ast::{AttrStyle, ast};
+use rustc_error_messages::{DiagArgValue, IntoDiagArg};
 use rustc_macros::{Decodable, Encodable, HashStable_Generic, PrintAttribute};
 use rustc_span::def_id::DefId;
 use rustc_span::hygiene::Transparency;
 use rustc_span::{Ident, Span, Symbol};
+pub use rustc_target::spec::SanitizerSet;
 use thin_vec::ThinVec;
 
 use crate::attrs::pretty_printing::PrintAttribute;
@@ -187,6 +192,176 @@ pub enum CfgEntry {
     Version(Option<RustcVersion>, Span),
 }
 
+/// Possible values for the `#[linkage]` attribute, allowing to specify the
+/// linkage type for a `MonoItem`.
+///
+/// See <https://llvm.org/docs/LangRef.html#linkage-types> for more details about these variants.
+#[derive(Encodable, Decodable, Clone, Copy, Debug, PartialEq, Eq, Hash)]
+#[derive(HashStable_Generic, PrintAttribute)]
+pub enum Linkage {
+    AvailableExternally,
+    Common,
+    ExternalWeak,
+    External,
+    Internal,
+    LinkOnceAny,
+    LinkOnceODR,
+    WeakAny,
+    WeakODR,
+}
+
+#[derive(Clone, Copy, Decodable, Debug, Encodable, PartialEq)]
+#[derive(HashStable_Generic, PrintAttribute)]
+pub enum MirDialect {
+    Analysis,
+    Built,
+    Runtime,
+}
+
+impl IntoDiagArg for MirDialect {
+    fn into_diag_arg(self, _path: &mut Option<PathBuf>) -> DiagArgValue {
+        let arg = match self {
+            MirDialect::Analysis => "analysis",
+            MirDialect::Built => "built",
+            MirDialect::Runtime => "runtime",
+        };
+        DiagArgValue::Str(Cow::Borrowed(arg))
+    }
+}
+
+#[derive(Clone, Copy, Decodable, Debug, Encodable, PartialEq)]
+#[derive(HashStable_Generic, PrintAttribute)]
+pub enum MirPhase {
+    Initial,
+    PostCleanup,
+    Optimized,
+}
+
+impl IntoDiagArg for MirPhase {
+    fn into_diag_arg(self, _path: &mut Option<PathBuf>) -> DiagArgValue {
+        let arg = match self {
+            MirPhase::Initial => "initial",
+            MirPhase::PostCleanup => "post-cleanup",
+            MirPhase::Optimized => "optimized",
+        };
+        DiagArgValue::Str(Cow::Borrowed(arg))
+    }
+}
+
+/// Different ways that the PE Format can decorate a symbol name.
+/// From <https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-name-type>
+#[derive(
+    Copy,
+    Clone,
+    Debug,
+    Encodable,
+    Decodable,
+    HashStable_Generic,
+    PartialEq,
+    Eq,
+    PrintAttribute
+)]
+pub enum PeImportNameType {
+    /// IMPORT_ORDINAL
+    /// Uses the ordinal (i.e., a number) rather than the name.
+    Ordinal(u16),
+    /// Same as IMPORT_NAME
+    /// Name is decorated with all prefixes and suffixes.
+    Decorated,
+    /// Same as IMPORT_NAME_NOPREFIX
+    /// Prefix (e.g., the leading `_` or `@`) is skipped, but suffix is kept.
+    NoPrefix,
+    /// Same as IMPORT_NAME_UNDECORATE
+    /// Prefix (e.g., the leading `_` or `@`) and suffix (the first `@` and all
+    /// trailing characters) are skipped.
+    Undecorated,
+}
+
+#[derive(
+    Copy,
+    Clone,
+    Debug,
+    PartialEq,
+    Eq,
+    PartialOrd,
+    Ord,
+    Hash,
+    Encodable,
+    Decodable,
+    PrintAttribute
+)]
+#[derive(HashStable_Generic)]
+pub enum NativeLibKind {
+    /// Static library (e.g. `libfoo.a` on Linux or `foo.lib` on Windows/MSVC)
+    Static {
+        /// Whether to bundle objects from static library into produced rlib
+        bundle: Option<bool>,
+        /// Whether to link static library without throwing any object files away
+        whole_archive: Option<bool>,
+    },
+    /// Dynamic library (e.g. `libfoo.so` on Linux)
+    /// or an import library corresponding to a dynamic library (e.g. `foo.lib` on Windows/MSVC).
+    Dylib {
+        /// Whether the dynamic library will be linked only if it satisfies some undefined symbols
+        as_needed: Option<bool>,
+    },
+    /// Dynamic library (e.g. `foo.dll` on Windows) without a corresponding import library.
+    /// On Linux, it refers to a generated shared library stub.
+    RawDylib,
+    /// A macOS-specific kind of dynamic libraries.
+    Framework {
+        /// Whether the framework will be linked only if it satisfies some undefined symbols
+        as_needed: Option<bool>,
+    },
+    /// Argument which is passed to linker, relative order with libraries and other arguments
+    /// is preserved
+    LinkArg,
+
+    /// Module imported from WebAssembly
+    WasmImportModule,
+
+    /// The library kind wasn't specified, `Dylib` is currently used as a default.
+    Unspecified,
+}
+
+impl NativeLibKind {
+    pub fn has_modifiers(&self) -> bool {
+        match self {
+            NativeLibKind::Static { bundle, whole_archive } => {
+                bundle.is_some() || whole_archive.is_some()
+            }
+            NativeLibKind::Dylib { as_needed } | NativeLibKind::Framework { as_needed } => {
+                as_needed.is_some()
+            }
+            NativeLibKind::RawDylib
+            | NativeLibKind::Unspecified
+            | NativeLibKind::LinkArg
+            | NativeLibKind::WasmImportModule => false,
+        }
+    }
+
+    pub fn is_statically_included(&self) -> bool {
+        matches!(self, NativeLibKind::Static { .. })
+    }
+
+    pub fn is_dllimport(&self) -> bool {
+        matches!(
+            self,
+            NativeLibKind::Dylib { .. } | NativeLibKind::RawDylib | NativeLibKind::Unspecified
+        )
+    }
+}
+
+#[derive(Debug, Encodable, Decodable, Clone, HashStable_Generic, PrintAttribute)]
+pub struct LinkEntry {
+    pub span: Span,
+    pub kind: NativeLibKind,
+    pub name: Symbol,
+    pub cfg: Option<CfgEntry>,
+    pub verbatim: Option<bool>,
+    pub import_name_type: Option<(PeImportNameType, Span)>,
+}
+
 /// Represents parsed *built-in* inert attributes.
 ///
 /// ## Overview
@@ -306,6 +481,12 @@ pub enum AttributeKind {
     /// Represents `#[coverage(..)]`.
     Coverage(Span, CoverageAttrKind),
 
+    /// Represents `#[crate_name = ...]`
+    CrateName { name: Symbol, name_span: Span, attr_span: Span, style: AttrStyle },
+
+    /// Represents `#[custom_mir]`.
+    CustomMir(Option<(MirDialect, Span)>, Option<(MirPhase, Span)>, Span),
+
     ///Represents `#[rustc_deny_explicit_impl]`.
     DenyExplicitImpl(Span),
 
@@ -351,6 +532,9 @@ pub enum AttributeKind {
     /// Represents `#[inline]` and `#[rustc_force_inline]`.
     Inline(InlineAttr, Span),
 
+    /// Represents `#[link]`.
+    Link(ThinVec<LinkEntry>, Span),
+
     /// Represents `#[link_name]`.
     LinkName { name: Symbol, span: Span },
 
@@ -360,6 +544,9 @@ pub enum AttributeKind {
     /// Represents [`#[link_section]`](https://doc.rust-lang.org/reference/abi.html#the-link_section-attribute)
     LinkSection { name: Symbol, span: Span },
 
+    /// Represents `#[linkage]`.
+    Linkage(Linkage, Span),
+
     /// Represents `#[loop_match]`.
     LoopMatch(Span),
 
@@ -439,6 +626,12 @@ pub enum AttributeKind {
     /// Represents `#[rustc_object_lifetime_default]`.
     RustcObjectLifetimeDefault,
 
+    /// Represents `#[sanitize]`
+    ///
+    /// the on set and off set are distjoint since there's a third option: unset.
+    /// a node may not set the sanitizer setting in which case it inherits from parents.
+    Sanitize { on_set: SanitizerSet, off_set: SanitizerSet, span: Span },
+
     /// Represents `#[should_panic]`
     ShouldPanic { reason: Option<Symbol>, span: Span },
 
@@ -458,8 +651,9 @@ pub enum AttributeKind {
     /// Represents `#[rustc_std_internal_symbol]`.
     StdInternalSymbol(Span),
 
-    /// Represents `#[target_feature(enable = "...")]`
-    TargetFeature(ThinVec<(Symbol, Span)>, Span),
+    /// Represents `#[target_feature(enable = "...")]` and
+    /// `#[unsafe(force_target_feature(enable = "...")]`.
+    TargetFeature { features: ThinVec<(Symbol, Span)>, attr_span: Span, was_forced: bool },
 
     /// Represents `#[track_caller]`
     TrackCaller(Span),
diff --git a/compiler/rustc_hir/src/attrs/encode_cross_crate.rs b/compiler/rustc_hir/src/attrs/encode_cross_crate.rs
index 7ce624dcc55..3810bb6d003 100644
--- a/compiler/rustc_hir/src/attrs/encode_cross_crate.rs
+++ b/compiler/rustc_hir/src/attrs/encode_cross_crate.rs
@@ -7,6 +7,11 @@ pub enum EncodeCrossCrate {
 }
 
 impl AttributeKind {
+    /// Whether this attribute should be encoded in metadata files.
+    ///
+    /// If this is "Yes", then another crate can do `tcx.get_all_attrs(did)` for a did in this crate, and get the attribute.
+    /// When this is No, the attribute is filtered out while encoding and other crate won't be able to observe it.
+    /// This can be unexpectedly good for performance, so unless necessary for cross-crate compilation, prefer No.
     pub fn encode_cross_crate(&self) -> EncodeCrossCrate {
         use AttributeKind::*;
         use EncodeCrossCrate::*;
@@ -31,6 +36,8 @@ impl AttributeKind {
             ConstTrait(..) => No,
             Coroutine(..) => No,
             Coverage(..) => No,
+            CrateName { .. } => No,
+            CustomMir(_, _, _) => Yes,
             DenyExplicitImpl(..) => No,
             Deprecation { .. } => Yes,
             DoNotImplementViaObject(..) => No,
@@ -43,9 +50,11 @@ impl AttributeKind {
             Fundamental { .. } => Yes,
             Ignore { .. } => No,
             Inline(..) => No,
+            Link(..) => No,
             LinkName { .. } => Yes, // Needed for rustdoc
             LinkOrdinal { .. } => No,
             LinkSection { .. } => Yes, // Needed for rustdoc
+            Linkage(..) => No,
             LoopMatch(..) => No,
             MacroEscape(..) => No,
             MacroTransparency(..) => Yes,
@@ -71,12 +80,13 @@ impl AttributeKind {
             RustcLayoutScalarValidRangeEnd(..) => Yes,
             RustcLayoutScalarValidRangeStart(..) => Yes,
             RustcObjectLifetimeDefault => No,
+            Sanitize { .. } => No,
             ShouldPanic { .. } => No,
             SkipDuringMethodDispatch { .. } => No,
             SpecializationTrait(..) => No,
             Stability { .. } => Yes,
             StdInternalSymbol(..) => No,
-            TargetFeature(..) => No,
+            TargetFeature { .. } => No,
             TrackCaller(..) => Yes,
             TypeConst(..) => Yes,
             UnsafeSpecializationMarker(..) => No,
diff --git a/compiler/rustc_hir/src/attrs/pretty_printing.rs b/compiler/rustc_hir/src/attrs/pretty_printing.rs
index e44b29141da..e65de25b451 100644
--- a/compiler/rustc_hir/src/attrs/pretty_printing.rs
+++ b/compiler/rustc_hir/src/attrs/pretty_printing.rs
@@ -6,6 +6,7 @@ use rustc_ast::{AttrStyle, IntTy, UintTy};
 use rustc_ast_pretty::pp::Printer;
 use rustc_span::hygiene::Transparency;
 use rustc_span::{ErrorGuaranteed, Ident, Span, Symbol};
+use rustc_target::spec::SanitizerSet;
 use thin_vec::ThinVec;
 
 /// This trait is used to print attributes in `rustc_hir_pretty`.
@@ -146,4 +147,14 @@ macro_rules! print_tup {
 print_tup!(A B C D E F G H);
 print_skip!(Span, (), ErrorGuaranteed);
 print_disp!(u16, bool, NonZero<u32>);
-print_debug!(Symbol, Ident, UintTy, IntTy, Align, AttrStyle, CommentKind, Transparency);
+print_debug!(
+    Symbol,
+    Ident,
+    UintTy,
+    IntTy,
+    Align,
+    AttrStyle,
+    CommentKind,
+    Transparency,
+    SanitizerSet,
+);
diff --git a/compiler/rustc_hir/src/def.rs b/compiler/rustc_hir/src/def.rs
index 339d4e2eab7..8af4740f376 100644
--- a/compiler/rustc_hir/src/def.rs
+++ b/compiler/rustc_hir/src/def.rs
@@ -1,10 +1,12 @@
 use std::array::IntoIter;
+use std::borrow::Cow;
 use std::fmt::Debug;
 
 use rustc_ast as ast;
 use rustc_ast::NodeId;
 use rustc_data_structures::stable_hasher::ToStableHashKey;
 use rustc_data_structures::unord::UnordMap;
+use rustc_error_messages::{DiagArgValue, IntoDiagArg};
 use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use rustc_span::Symbol;
 use rustc_span::def_id::{DefId, LocalDefId};
@@ -31,6 +33,53 @@ pub enum CtorKind {
     Const,
 }
 
+/// A set of macro kinds, for macros that can have more than one kind
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Encodable, Decodable, Hash, Debug)]
+#[derive(HashStable_Generic)]
+pub struct MacroKinds(u8);
+bitflags::bitflags! {
+    impl MacroKinds: u8 {
+        const BANG = 1 << 0;
+        const ATTR = 1 << 1;
+        const DERIVE = 1 << 2;
+    }
+}
+
+impl From<MacroKind> for MacroKinds {
+    fn from(kind: MacroKind) -> Self {
+        match kind {
+            MacroKind::Bang => Self::BANG,
+            MacroKind::Attr => Self::ATTR,
+            MacroKind::Derive => Self::DERIVE,
+        }
+    }
+}
+
+impl MacroKinds {
+    /// Convert the MacroKinds to a static string.
+    ///
+    /// This hardcodes all the possibilities, in order to return a static string.
+    pub fn descr(self) -> &'static str {
+        match self {
+            // FIXME: change this to "function-like macro" and fix all tests
+            Self::BANG => "macro",
+            Self::ATTR => "attribute macro",
+            Self::DERIVE => "derive macro",
+            _ if self == (Self::ATTR | Self::BANG) => "attribute/function macro",
+            _ if self == (Self::DERIVE | Self::BANG) => "derive/function macro",
+            _ if self == (Self::ATTR | Self::DERIVE) => "attribute/derive macro",
+            _ if self.is_all() => "attribute/derive/function macro",
+            _ if self.is_empty() => "useless macro",
+            _ => unreachable!(),
+        }
+    }
+
+    /// Return an indefinite article (a/an) for use with `descr()`
+    pub fn article(self) -> &'static str {
+        if self.contains(Self::ATTR) { "an" } else { "a" }
+    }
+}
+
 /// An attribute that is not a macro; e.g., `#[inline]` or `#[rustfmt::skip]`.
 #[derive(Clone, Copy, PartialEq, Eq, Encodable, Decodable, Hash, Debug, HashStable_Generic)]
 pub enum NonMacroAttrKind {
@@ -101,7 +150,7 @@ pub enum DefKind {
     AssocConst,
 
     // Macro namespace
-    Macro(MacroKind),
+    Macro(MacroKinds),
 
     // Not namespaced (or they are, but we don't treat them so)
     ExternCrate,
@@ -177,7 +226,7 @@ impl DefKind {
             DefKind::AssocConst => "associated constant",
             DefKind::TyParam => "type parameter",
             DefKind::ConstParam => "const parameter",
-            DefKind::Macro(macro_kind) => macro_kind.descr(),
+            DefKind::Macro(kinds) => kinds.descr(),
             DefKind::LifetimeParam => "lifetime parameter",
             DefKind::Use => "import",
             DefKind::ForeignMod => "foreign module",
@@ -208,7 +257,7 @@ impl DefKind {
             | DefKind::Use
             | DefKind::InlineConst
             | DefKind::ExternCrate => "an",
-            DefKind::Macro(macro_kind) => macro_kind.article(),
+            DefKind::Macro(kinds) => kinds.article(),
             _ => "a",
         }
     }
@@ -539,6 +588,12 @@ pub enum Res<Id = hir::HirId> {
     Err,
 }
 
+impl<Id> IntoDiagArg for Res<Id> {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Str(Cow::Borrowed(self.descr()))
+    }
+}
+
 /// The result of resolving a path before lowering to HIR,
 /// with "module" segments resolved and associated item
 /// segments deferred to type checking.
@@ -626,6 +681,12 @@ impl Namespace {
     }
 }
 
+impl IntoDiagArg for Namespace {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Str(Cow::Borrowed(self.descr()))
+    }
+}
+
 impl<CTX: crate::HashStableContext> ToStableHashKey<CTX> for Namespace {
     type KeyType = Namespace;
 
@@ -845,10 +906,10 @@ impl<Id> Res<Id> {
         )
     }
 
-    pub fn macro_kind(self) -> Option<MacroKind> {
+    pub fn macro_kinds(self) -> Option<MacroKinds> {
         match self {
-            Res::Def(DefKind::Macro(kind), _) => Some(kind),
-            Res::NonMacroAttr(..) => Some(MacroKind::Attr),
+            Res::Def(DefKind::Macro(kinds), _) => Some(kinds),
+            Res::NonMacroAttr(..) => Some(MacroKinds::ATTR),
             _ => None,
         }
     }
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index b27c223527e..e397c286de2 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -1,4 +1,5 @@
 // ignore-tidy-filelength
+use std::borrow::Cow;
 use std::fmt;
 
 use rustc_abi::ExternAbi;
@@ -17,10 +18,10 @@ pub use rustc_ast::{
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::sorted_map::SortedMap;
 use rustc_data_structures::tagged_ptr::TaggedRef;
+use rustc_error_messages::{DiagArgValue, IntoDiagArg};
 use rustc_index::IndexVec;
 use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use rustc_span::def_id::LocalDefId;
-use rustc_span::hygiene::MacroKind;
 use rustc_span::source_map::Spanned;
 use rustc_span::{BytePos, DUMMY_SP, ErrorGuaranteed, Ident, Span, Symbol, kw, sym};
 use rustc_target::asm::InlineAsmRegOrRegClass;
@@ -30,7 +31,7 @@ use tracing::debug;
 
 use crate::LangItem;
 use crate::attrs::AttributeKind;
-use crate::def::{CtorKind, DefKind, PerNS, Res};
+use crate::def::{CtorKind, DefKind, MacroKinds, PerNS, Res};
 use crate::def_id::{DefId, LocalDefIdMap};
 pub(crate) use crate::hir_id::{HirId, ItemLocalId, ItemLocalMap, OwnerId};
 use crate::intravisit::{FnKind, VisitorExt};
@@ -1160,6 +1161,12 @@ pub struct AttrPath {
     pub span: Span,
 }
 
+impl IntoDiagArg for AttrPath {
+    fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        self.to_string().into_diag_arg(path)
+    }
+}
+
 impl AttrPath {
     pub fn from_ast(path: &ast::Path) -> Self {
         AttrPath {
@@ -1233,6 +1240,13 @@ impl Attribute {
             _ => None,
         }
     }
+
+    pub fn is_parsed_attr(&self) -> bool {
+        match self {
+            Attribute::Parsed(_) => true,
+            Attribute::Unparsed(_) => false,
+        }
+    }
 }
 
 impl AttributeExt for Attribute {
@@ -1303,14 +1317,10 @@ impl AttributeExt for Attribute {
         match &self {
             Attribute::Unparsed(u) => u.span,
             // FIXME: should not be needed anymore when all attrs are parsed
-            Attribute::Parsed(AttributeKind::Deprecation { span, .. }) => *span,
             Attribute::Parsed(AttributeKind::DocComment { span, .. }) => *span,
-            Attribute::Parsed(AttributeKind::MacroUse { span, .. }) => *span,
-            Attribute::Parsed(AttributeKind::MayDangle(span)) => *span,
-            Attribute::Parsed(AttributeKind::Ignore { span, .. }) => *span,
-            Attribute::Parsed(AttributeKind::ShouldPanic { span, .. }) => *span,
-            Attribute::Parsed(AttributeKind::AutomaticallyDerived(span)) => *span,
+            Attribute::Parsed(AttributeKind::Deprecation { span, .. }) => *span,
             Attribute::Parsed(AttributeKind::AllowInternalUnsafe(span)) => *span,
+            Attribute::Parsed(AttributeKind::Linkage(_, span)) => *span,
             a => panic!("can't get the span of an arbitrary parsed attribute: {a:?}"),
         }
     }
@@ -2257,8 +2267,15 @@ impl fmt::Display for ConstContext {
     }
 }
 
-// NOTE: `IntoDiagArg` impl for `ConstContext` lives in `rustc_errors`
-// due to a cyclical dependency between hir and that crate.
+impl IntoDiagArg for ConstContext {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Str(Cow::Borrowed(match self {
+            ConstContext::ConstFn => "const_fn",
+            ConstContext::Static(_) => "static",
+            ConstContext::Const { .. } => "const",
+        }))
+    }
+}
 
 /// A literal.
 pub type Lit = Spanned<LitKind>;
@@ -4157,7 +4174,7 @@ impl<'hir> Item<'hir> {
         expect_fn, (Ident, &FnSig<'hir>, &'hir Generics<'hir>, BodyId),
             ItemKind::Fn { ident, sig, generics, body, .. }, (*ident, sig, generics, *body);
 
-        expect_macro, (Ident, &ast::MacroDef, MacroKind),
+        expect_macro, (Ident, &ast::MacroDef, MacroKinds),
             ItemKind::Macro(ident, def, mk), (*ident, def, *mk);
 
         expect_mod, (Ident, &'hir Mod<'hir>), ItemKind::Mod(ident, m), (*ident, m);
@@ -4336,7 +4353,7 @@ pub enum ItemKind<'hir> {
         has_body: bool,
     },
     /// A MBE macro definition (`macro_rules!` or `macro`).
-    Macro(Ident, &'hir ast::MacroDef, MacroKind),
+    Macro(Ident, &'hir ast::MacroDef, MacroKinds),
     /// A module.
     Mod(Ident, &'hir Mod<'hir>),
     /// An external module, e.g. `extern { .. }`.
diff --git a/compiler/rustc_hir/src/lang_items.rs b/compiler/rustc_hir/src/lang_items.rs
index 75c04b23ed6..0464665b41f 100644
--- a/compiler/rustc_hir/src/lang_items.rs
+++ b/compiler/rustc_hir/src/lang_items.rs
@@ -286,6 +286,7 @@ language_item_table! {
     Panic,                   sym::panic,               panic_fn,                   Target::Fn,             GenericRequirement::Exact(0);
     PanicNounwind,           sym::panic_nounwind,      panic_nounwind,             Target::Fn,             GenericRequirement::Exact(0);
     PanicFmt,                sym::panic_fmt,           panic_fmt,                  Target::Fn,             GenericRequirement::None;
+    PanicDisplay,            sym::panic_display,       panic_display,              Target::Fn,             GenericRequirement::None;
     ConstPanicFmt,           sym::const_panic_fmt,     const_panic_fmt,            Target::Fn,             GenericRequirement::None;
     PanicBoundsCheck,        sym::panic_bounds_check,  panic_bounds_check_fn,      Target::Fn,             GenericRequirement::Exact(0);
     PanicMisalignedPointerDereference, sym::panic_misaligned_pointer_dereference, panic_misaligned_pointer_dereference_fn, Target::Fn, GenericRequirement::Exact(0);
@@ -436,6 +437,9 @@ language_item_table! {
     DefaultTrait1,           sym::default_trait1,      default_trait1_trait,       Target::Trait,          GenericRequirement::None;
 
     ContractCheckEnsures,     sym::contract_check_ensures,      contract_check_ensures_fn,      Target::Fn, GenericRequirement::None;
+
+    // Reborrowing related lang-items
+    Reborrow,                sym::reborrow,            reborrow,                   Target::Trait,          GenericRequirement::Exact(0);
 }
 
 /// The requirement imposed on the generics of a lang item
diff --git a/compiler/rustc_hir/src/lib.rs b/compiler/rustc_hir/src/lib.rs
index f1212d07ff6..78fc63753a2 100644
--- a/compiler/rustc_hir/src/lib.rs
+++ b/compiler/rustc_hir/src/lib.rs
@@ -3,14 +3,11 @@
 //! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/hir.html
 
 // tidy-alphabetical-start
-#![allow(internal_features)]
 #![feature(associated_type_defaults)]
 #![feature(closure_track_caller)]
 #![feature(debug_closure_helpers)]
 #![feature(exhaustive_patterns)]
-#![feature(negative_impls)]
 #![feature(never_type)]
-#![feature(rustc_attrs)]
 #![feature(variant_count)]
 #![recursion_limit = "256"]
 // tidy-alphabetical-end
@@ -25,7 +22,7 @@ pub mod definitions;
 pub mod diagnostic_items;
 pub use rustc_span::def_id;
 mod hir;
-pub mod hir_id;
+pub use rustc_hir_id::{self as hir_id, *};
 pub mod intravisit;
 pub mod lang_items;
 pub mod lints;
@@ -41,7 +38,6 @@ mod tests;
 
 #[doc(no_inline)]
 pub use hir::*;
-pub use hir_id::*;
 pub use lang_items::{LangItem, LanguageItems};
 pub use stability::*;
 pub use stable_hash_impls::HashStableContext;
diff --git a/compiler/rustc_hir/src/lints.rs b/compiler/rustc_hir/src/lints.rs
index c55a41eb2b7..0b24052b453 100644
--- a/compiler/rustc_hir/src/lints.rs
+++ b/compiler/rustc_hir/src/lints.rs
@@ -2,7 +2,7 @@ use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_macros::HashStable_Generic;
 use rustc_span::Span;
 
-use crate::HirId;
+use crate::{AttrPath, HirId, Target};
 
 #[derive(Debug)]
 pub struct DelayedLints {
@@ -34,4 +34,6 @@ pub enum AttributeLintKind {
     UnusedDuplicate { this: Span, other: Span, warning: bool },
     IllFormedAttributeInput { suggestions: Vec<String> },
     EmptyAttribute { first_span: Span },
+    InvalidTarget { name: AttrPath, target: Target, applied: Vec<String>, only: &'static str },
+    InvalidStyle { name: AttrPath, is_used_as_inner: bool, target: Target, target_span: Span },
 }
diff --git a/compiler/rustc_hir/src/stable_hash_impls.rs b/compiler/rustc_hir/src/stable_hash_impls.rs
index ecc608d437b..16e8bac3d8a 100644
--- a/compiler/rustc_hir/src/stable_hash_impls.rs
+++ b/compiler/rustc_hir/src/stable_hash_impls.rs
@@ -5,7 +5,7 @@ use crate::HashIgnoredAttrId;
 use crate::hir::{
     AttributeMap, BodyId, Crate, ForeignItemId, ImplItemId, ItemId, OwnerNodes, TraitItemId,
 };
-use crate::hir_id::{HirId, ItemLocalId};
+use crate::hir_id::ItemLocalId;
 use crate::lints::DelayedLints;
 
 /// Requirements for a `StableHashingContext` to be used in this crate.
@@ -15,25 +15,6 @@ pub trait HashStableContext: rustc_ast::HashStableContext + rustc_abi::HashStabl
     fn hash_attr_id(&mut self, id: &HashIgnoredAttrId, hasher: &mut StableHasher);
 }
 
-impl<HirCtx: crate::HashStableContext> ToStableHashKey<HirCtx> for HirId {
-    type KeyType = (DefPathHash, ItemLocalId);
-
-    #[inline]
-    fn to_stable_hash_key(&self, hcx: &HirCtx) -> (DefPathHash, ItemLocalId) {
-        let def_path_hash = self.owner.def_id.to_stable_hash_key(hcx);
-        (def_path_hash, self.local_id)
-    }
-}
-
-impl<HirCtx: crate::HashStableContext> ToStableHashKey<HirCtx> for ItemLocalId {
-    type KeyType = ItemLocalId;
-
-    #[inline]
-    fn to_stable_hash_key(&self, _: &HirCtx) -> ItemLocalId {
-        *self
-    }
-}
-
 impl<HirCtx: crate::HashStableContext> ToStableHashKey<HirCtx> for BodyId {
     type KeyType = (DefPathHash, ItemLocalId);
 
diff --git a/compiler/rustc_hir/src/target.rs b/compiler/rustc_hir/src/target.rs
index d617f44f8d8..dcac51b10b4 100644
--- a/compiler/rustc_hir/src/target.rs
+++ b/compiler/rustc_hir/src/target.rs
@@ -6,23 +6,34 @@
 
 use std::fmt::{self, Display};
 
+use rustc_ast::visit::AssocCtxt;
+use rustc_ast::{AssocItemKind, ForeignItemKind, ast};
+use rustc_macros::HashStable_Generic;
+
 use crate::def::DefKind;
 use crate::{Item, ItemKind, TraitItem, TraitItemKind, hir};
 
-#[derive(Copy, Clone, PartialEq, Debug)]
+#[derive(Copy, Clone, PartialEq, Debug, Eq, HashStable_Generic)]
 pub enum GenericParamKind {
     Type,
     Lifetime,
     Const,
 }
 
-#[derive(Copy, Clone, PartialEq, Debug)]
+#[derive(Copy, Clone, PartialEq, Debug, Eq, HashStable_Generic)]
 pub enum MethodKind {
-    Trait { body: bool },
+    /// Method in a `trait Trait` block
+    Trait {
+        /// Whether a default is provided for this method
+        body: bool,
+    },
+    /// Method in a `impl Trait for Type` block
+    TraitImpl,
+    /// Method in a `impl Type` block
     Inherent,
 }
 
-#[derive(Copy, Clone, PartialEq, Debug)]
+#[derive(Copy, Clone, PartialEq, Debug, Eq, HashStable_Generic)]
 pub enum Target {
     ExternCrate,
     Use,
@@ -57,6 +68,9 @@ pub enum Target {
     PatField,
     ExprField,
     WherePredicate,
+    MacroCall,
+    Crate,
+    Delegation { mac: bool },
 }
 
 impl Display for Target {
@@ -65,6 +79,8 @@ impl Display for Target {
     }
 }
 
+rustc_error_messages::into_diag_arg_using_display!(Target);
+
 impl Target {
     pub fn is_associated_item(self) -> bool {
         match self {
@@ -98,7 +114,10 @@ impl Target {
             | Target::Param
             | Target::PatField
             | Target::ExprField
-            | Target::WherePredicate => false,
+            | Target::MacroCall
+            | Target::Crate
+            | Target::WherePredicate
+            | Target::Delegation { .. } => false,
         }
     }
 
@@ -146,6 +165,39 @@ impl Target {
         }
     }
 
+    pub fn from_ast_item(item: &ast::Item) -> Target {
+        match item.kind {
+            ast::ItemKind::ExternCrate(..) => Target::ExternCrate,
+            ast::ItemKind::Use(..) => Target::Use,
+            ast::ItemKind::Static { .. } => Target::Static,
+            ast::ItemKind::Const(..) => Target::Const,
+            ast::ItemKind::Fn { .. } => Target::Fn,
+            ast::ItemKind::Mod(..) => Target::Mod,
+            ast::ItemKind::ForeignMod { .. } => Target::ForeignMod,
+            ast::ItemKind::GlobalAsm { .. } => Target::GlobalAsm,
+            ast::ItemKind::TyAlias(..) => Target::TyAlias,
+            ast::ItemKind::Enum(..) => Target::Enum,
+            ast::ItemKind::Struct(..) => Target::Struct,
+            ast::ItemKind::Union(..) => Target::Union,
+            ast::ItemKind::Trait(..) => Target::Trait,
+            ast::ItemKind::TraitAlias(..) => Target::TraitAlias,
+            ast::ItemKind::Impl(ref i) => Target::Impl { of_trait: i.of_trait.is_some() },
+            ast::ItemKind::MacCall(..) => Target::MacroCall,
+            ast::ItemKind::MacroDef(..) => Target::MacroDef,
+            ast::ItemKind::Delegation(..) => Target::Delegation { mac: false },
+            ast::ItemKind::DelegationMac(..) => Target::Delegation { mac: true },
+        }
+    }
+
+    pub fn from_foreign_item_kind(kind: &ast::ForeignItemKind) -> Target {
+        match kind {
+            ForeignItemKind::Static(_) => Target::ForeignStatic,
+            ForeignItemKind::Fn(_) => Target::ForeignFn,
+            ForeignItemKind::TyAlias(_) => Target::ForeignTy,
+            ForeignItemKind::MacCall(_) => Target::MacroCall,
+        }
+    }
+
     pub fn from_trait_item(trait_item: &TraitItem<'_>) -> Target {
         match trait_item.kind {
             TraitItemKind::Const(..) => Target::AssocConst,
@@ -183,12 +235,40 @@ impl Target {
         }
     }
 
+    pub fn from_assoc_item_kind(kind: &ast::AssocItemKind, assoc_ctxt: AssocCtxt) -> Target {
+        match kind {
+            AssocItemKind::Const(_) => Target::AssocConst,
+            AssocItemKind::Fn(f) => Target::Method(match assoc_ctxt {
+                AssocCtxt::Trait => MethodKind::Trait { body: f.body.is_some() },
+                AssocCtxt::Impl { of_trait } => {
+                    if of_trait {
+                        MethodKind::TraitImpl
+                    } else {
+                        MethodKind::Inherent
+                    }
+                }
+            }),
+            AssocItemKind::Type(_) => Target::AssocTy,
+            AssocItemKind::Delegation(_) => Target::Delegation { mac: false },
+            AssocItemKind::DelegationMac(_) => Target::Delegation { mac: true },
+            AssocItemKind::MacCall(_) => Target::MacroCall,
+        }
+    }
+
+    pub fn from_expr(expr: &ast::Expr) -> Self {
+        match &expr.kind {
+            ast::ExprKind::Closure(..) | ast::ExprKind::Gen(..) => Self::Closure,
+            ast::ExprKind::Paren(e) => Self::from_expr(&e),
+            _ => Self::Expression,
+        }
+    }
+
     pub fn name(self) -> &'static str {
         match self {
             Target::ExternCrate => "extern crate",
             Target::Use => "use",
-            Target::Static => "static item",
-            Target::Const => "constant item",
+            Target::Static => "static",
+            Target::Const => "constant",
             Target::Fn => "function",
             Target::Closure => "closure",
             Target::Mod => "module",
@@ -202,8 +282,7 @@ impl Target {
             Target::Union => "union",
             Target::Trait => "trait",
             Target::TraitAlias => "trait alias",
-            Target::Impl { of_trait: false } => "inherent implementation block",
-            Target::Impl { of_trait: true } => "trait implementation block",
+            Target::Impl { .. } => "implementation block",
             Target::Expression => "expression",
             Target::Statement => "statement",
             Target::Arm => "match arm",
@@ -212,12 +291,13 @@ impl Target {
                 MethodKind::Inherent => "inherent method",
                 MethodKind::Trait { body: false } => "required trait method",
                 MethodKind::Trait { body: true } => "provided trait method",
+                MethodKind::TraitImpl => "trait method in an impl block",
             },
             Target::AssocTy => "associated type",
             Target::ForeignFn => "foreign function",
             Target::ForeignStatic => "foreign static item",
             Target::ForeignTy => "foreign type",
-            Target::GenericParam { kind, has_default: _ } => match kind {
+            Target::GenericParam { kind, .. } => match kind {
                 GenericParamKind::Type => "type parameter",
                 GenericParamKind::Lifetime => "lifetime parameter",
                 GenericParamKind::Const => "const parameter",
@@ -227,6 +307,60 @@ impl Target {
             Target::PatField => "pattern field",
             Target::ExprField => "struct field",
             Target::WherePredicate => "where predicate",
+            Target::MacroCall => "macro call",
+            Target::Crate => "crate",
+            Target::Delegation { .. } => "delegation",
+        }
+    }
+
+    pub fn plural_name(self) -> &'static str {
+        match self {
+            Target::ExternCrate => "extern crates",
+            Target::Use => "use statements",
+            Target::Static => "statics",
+            Target::Const => "constants",
+            Target::Fn => "functions",
+            Target::Closure => "closures",
+            Target::Mod => "modules",
+            Target::ForeignMod => "foreign modules",
+            Target::GlobalAsm => "global asms",
+            Target::TyAlias => "type aliases",
+            Target::Enum => "enums",
+            Target::Variant => "enum variants",
+            Target::Struct => "structs",
+            Target::Field => "struct fields",
+            Target::Union => "unions",
+            Target::Trait => "traits",
+            Target::TraitAlias => "trait aliases",
+            Target::Impl { of_trait: false } => "inherent impl blocks",
+            Target::Impl { of_trait: true } => "trait impl blocks",
+            Target::Expression => "expressions",
+            Target::Statement => "statements",
+            Target::Arm => "match arms",
+            Target::AssocConst => "associated consts",
+            Target::Method(kind) => match kind {
+                MethodKind::Inherent => "inherent methods",
+                MethodKind::Trait { body: false } => "required trait methods",
+                MethodKind::Trait { body: true } => "provided trait methods",
+                MethodKind::TraitImpl => "trait methods in impl blocks",
+            },
+            Target::AssocTy => "associated types",
+            Target::ForeignFn => "foreign functions",
+            Target::ForeignStatic => "foreign statics",
+            Target::ForeignTy => "foreign types",
+            Target::GenericParam { kind, has_default: _ } => match kind {
+                GenericParamKind::Type => "type parameters",
+                GenericParamKind::Lifetime => "lifetime parameters",
+                GenericParamKind::Const => "const parameters",
+            },
+            Target::MacroDef => "macro defs",
+            Target::Param => "function params",
+            Target::PatField => "pattern fields",
+            Target::ExprField => "struct fields",
+            Target::WherePredicate => "where predicates",
+            Target::MacroCall => "macro calls",
+            Target::Crate => "crates",
+            Target::Delegation { .. } => "delegations",
         }
     }
 }
diff --git a/compiler/rustc_hir/src/version.rs b/compiler/rustc_hir/src/version.rs
index ab5ab026b4c..bc2c38a4935 100644
--- a/compiler/rustc_hir/src/version.rs
+++ b/compiler/rustc_hir/src/version.rs
@@ -1,6 +1,8 @@
+use std::borrow::Cow;
 use std::fmt::{self, Display};
 use std::sync::OnceLock;
 
+use rustc_error_messages::{DiagArgValue, IntoDiagArg};
 use rustc_macros::{
     Decodable, Encodable, HashStable_Generic, PrintAttribute, current_rustc_version,
 };
@@ -45,3 +47,9 @@ impl Display for RustcVersion {
         write!(formatter, "{}.{}.{}", self.major, self.minor, self.patch)
     }
 }
+
+impl IntoDiagArg for RustcVersion {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Str(Cow::Owned(self.to_string()))
+    }
+}
diff --git a/compiler/rustc_hir_analysis/Cargo.toml b/compiler/rustc_hir_analysis/Cargo.toml
index e5017794d8f..bb86beb2251 100644
--- a/compiler/rustc_hir_analysis/Cargo.toml
+++ b/compiler/rustc_hir_analysis/Cargo.toml
@@ -9,7 +9,7 @@ doctest = false
 
 [dependencies]
 # tidy-alphabetical-start
-itertools = "0.12"
+itertools.workspace = true
 rustc_abi = { path = "../rustc_abi" }
 rustc_arena = { path = "../rustc_arena" }
 rustc_ast = { path = "../rustc_ast" }
@@ -29,5 +29,5 @@ rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 rustc_trait_selection = { path = "../rustc_trait_selection" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_hir_analysis/messages.ftl b/compiler/rustc_hir_analysis/messages.ftl
index 2428c1aa29f..06f2ec512ab 100644
--- a/compiler/rustc_hir_analysis/messages.ftl
+++ b/compiler/rustc_hir_analysis/messages.ftl
@@ -509,10 +509,6 @@ hir_analysis_supertrait_item_shadowee = item from `{$supertrait}` is shadowed by
 
 hir_analysis_supertrait_item_shadowing = trait item `{$item}` from `{$subtrait}` shadows identically named item from supertrait
 
-hir_analysis_tait_forward_compat2 = item does not constrain `{$opaque_type}`
-    .note = consider removing `#[define_opaque]` or adding an empty `#[define_opaque()]`
-    .opaque = this opaque type is supposed to be constrained
-
 hir_analysis_target_feature_on_main = `main` function is not allowed to have `#[target_feature]`
 
 hir_analysis_too_large_static = extern static is too large for the target architecture
diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
index 161a8566b04..eccb88a938f 100644
--- a/compiler/rustc_hir_analysis/src/check/check.rs
+++ b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -2053,3 +2053,29 @@ pub(super) fn check_coroutine_obligations(
 
     Ok(())
 }
+
+pub(super) fn check_potentially_region_dependent_goals<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    def_id: LocalDefId,
+) -> Result<(), ErrorGuaranteed> {
+    if !tcx.next_trait_solver_globally() {
+        return Ok(());
+    }
+    let typeck_results = tcx.typeck(def_id);
+    let param_env = tcx.param_env(def_id);
+
+    // We use `TypingMode::Borrowck` as we want to use the opaque types computed by HIR typeck.
+    let typing_mode = TypingMode::borrowck(tcx, def_id);
+    let infcx = tcx.infer_ctxt().ignoring_regions().build(typing_mode);
+    let ocx = ObligationCtxt::new_with_diagnostics(&infcx);
+    for (predicate, cause) in &typeck_results.potentially_region_dependent_goals {
+        let predicate = fold_regions(tcx, *predicate, |_, _| {
+            infcx.next_region_var(RegionVariableOrigin::Misc(cause.span))
+        });
+        ocx.register_obligation(Obligation::new(tcx, cause.clone(), param_env, predicate));
+    }
+
+    let errors = ocx.select_all_or_error();
+    debug!(?errors);
+    if errors.is_empty() { Ok(()) } else { Err(infcx.err_ctxt().report_fulfillment_errors(errors)) }
+}
diff --git a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
index 6767e5ed88d..e4827256193 100644
--- a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
+++ b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
@@ -445,10 +445,10 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>(
     tcx: TyCtxt<'tcx>,
     impl_m_def_id: LocalDefId,
 ) -> Result<&'tcx DefIdMap<ty::EarlyBinder<'tcx, Ty<'tcx>>>, ErrorGuaranteed> {
-    let impl_m = tcx.opt_associated_item(impl_m_def_id.to_def_id()).unwrap();
-    let trait_m = tcx.opt_associated_item(impl_m.trait_item_def_id.unwrap()).unwrap();
+    let impl_m = tcx.associated_item(impl_m_def_id.to_def_id());
+    let trait_m = tcx.associated_item(impl_m.trait_item_def_id.unwrap());
     let impl_trait_ref =
-        tcx.impl_trait_ref(impl_m.impl_container(tcx).unwrap()).unwrap().instantiate_identity();
+        tcx.impl_trait_ref(tcx.parent(impl_m_def_id.to_def_id())).unwrap().instantiate_identity();
     // First, check a few of the same things as `compare_impl_method`,
     // just so we don't ICE during instantiation later.
     check_method_is_structurally_compatible(tcx, impl_m, trait_m, impl_trait_ref, true)?;
diff --git a/compiler/rustc_hir_analysis/src/check/intrinsic.rs b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
index 4441dd6ebd6..cfc6bc2f3a0 100644
--- a/compiler/rustc_hir_analysis/src/check/intrinsic.rs
+++ b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
@@ -135,6 +135,11 @@ fn intrinsic_operation_unsafety(tcx: TyCtxt<'_>, intrinsic_id: LocalDefId) -> hi
         | sym::round_ties_even_f32
         | sym::round_ties_even_f64
         | sym::round_ties_even_f128
+        | sym::autodiff
+        | sym::prefetch_read_data
+        | sym::prefetch_write_data
+        | sym::prefetch_read_instruction
+        | sym::prefetch_write_instruction
         | sym::const_eval_select => hir::Safety::Safe,
         _ => hir::Safety::Unsafe,
     };
@@ -198,6 +203,7 @@ pub(crate) fn check_intrinsic_type(
     let safety = intrinsic_operation_unsafety(tcx, intrinsic_id);
     let n_lts = 0;
     let (n_tps, n_cts, inputs, output) = match intrinsic_name {
+        sym::autodiff => (4, 0, vec![param(0), param(1), param(2)], param(3)),
         sym::abort => (0, 0, vec![], tcx.types.never),
         sym::unreachable => (0, 0, vec![], tcx.types.never),
         sym::breakpoint => (0, 0, vec![], tcx.types.unit),
@@ -216,7 +222,7 @@ pub(crate) fn check_intrinsic_type(
         | sym::prefetch_write_data
         | sym::prefetch_read_instruction
         | sym::prefetch_write_instruction => {
-            (1, 0, vec![Ty::new_imm_ptr(tcx, param(0)), tcx.types.i32], tcx.types.unit)
+            (1, 1, vec![Ty::new_imm_ptr(tcx, param(0))], tcx.types.unit)
         }
         sym::needs_drop => (1, 0, vec![], tcx.types.bool),
 
diff --git a/compiler/rustc_hir_analysis/src/check/mod.rs b/compiler/rustc_hir_analysis/src/check/mod.rs
index 85445cb3c00..2e4b151d4dc 100644
--- a/compiler/rustc_hir_analysis/src/check/mod.rs
+++ b/compiler/rustc_hir_analysis/src/check/mod.rs
@@ -109,6 +109,7 @@ pub(super) fn provide(providers: &mut Providers) {
         collect_return_position_impl_trait_in_trait_tys,
         compare_impl_item: compare_impl_item::compare_impl_item,
         check_coroutine_obligations: check::check_coroutine_obligations,
+        check_potentially_region_dependent_goals: check::check_potentially_region_dependent_goals,
         check_type_wf: wfcheck::check_type_wf,
         check_well_formed: wfcheck::check_well_formed,
         ..*providers
diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
index c642435b989..e6a1f6d8d8b 100644
--- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs
+++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -2287,8 +2287,7 @@ fn lint_redundant_lifetimes<'tcx>(
             // Proceed
         }
         DefKind::AssocFn | DefKind::AssocTy | DefKind::AssocConst => {
-            let parent_def_id = tcx.local_parent(owner_id);
-            if matches!(tcx.def_kind(parent_def_id), DefKind::Impl { of_trait: true }) {
+            if tcx.trait_impl_of_assoc(owner_id.to_def_id()).is_some() {
                 // Don't check for redundant lifetimes for associated items of trait
                 // implementations, since the signature is required to be compatible
                 // with the trait, even if the implementation implies some lifetimes
diff --git a/compiler/rustc_hir_analysis/src/collect/type_of/opaque.rs b/compiler/rustc_hir_analysis/src/collect/type_of/opaque.rs
index 50e20a19eda..b6d898886ac 100644
--- a/compiler/rustc_hir_analysis/src/collect/type_of/opaque.rs
+++ b/compiler/rustc_hir_analysis/src/collect/type_of/opaque.rs
@@ -4,9 +4,10 @@ use rustc_hir::{self as hir, Expr, ImplItem, Item, Node, TraitItem, def, intravi
 use rustc_middle::bug;
 use rustc_middle::hir::nested_filter;
 use rustc_middle::ty::{self, DefiningScopeKind, Ty, TyCtxt, TypeVisitableExt};
+use rustc_trait_selection::opaque_types::report_item_does_not_constrain_error;
 use tracing::{debug, instrument, trace};
 
-use crate::errors::{TaitForwardCompat2, UnconstrainedOpaqueType};
+use crate::errors::UnconstrainedOpaqueType;
 
 /// Checks "defining uses" of opaque `impl Trait` in associated types.
 /// These can only be defined by associated items of the same trait.
@@ -127,14 +128,11 @@ impl<'tcx> TaitConstraintLocator<'tcx> {
     }
 
     fn non_defining_use_in_defining_scope(&mut self, item_def_id: LocalDefId) {
-        let guar = self.tcx.dcx().emit_err(TaitForwardCompat2 {
-            span: self
-                .tcx
-                .def_ident_span(item_def_id)
-                .unwrap_or_else(|| self.tcx.def_span(item_def_id)),
-            opaque_type_span: self.tcx.def_span(self.def_id),
-            opaque_type: self.tcx.def_path_str(self.def_id),
-        });
+        // We make sure that all opaque types get defined while
+        // type checking the defining scope, so this error is unreachable
+        // with the new solver.
+        assert!(!self.tcx.next_trait_solver_globally());
+        let guar = report_item_does_not_constrain_error(self.tcx, item_def_id, self.def_id, None);
         self.insert_found(ty::OpaqueHiddenType::new_error(self.tcx, guar));
     }
 
@@ -252,9 +250,7 @@ pub(super) fn find_opaque_ty_constraints_for_rpit<'tcx>(
             } else if let Some(hidden_ty) = tables.concrete_opaque_types.get(&def_id) {
                 hidden_ty.ty
             } else {
-                // FIXME(-Znext-solver): This should not be necessary and we should
-                // instead rely on inference variable fallback inside of typeck itself.
-
+                assert!(!tcx.next_trait_solver_globally());
                 // We failed to resolve the opaque type or it
                 // resolves to itself. We interpret this as the
                 // no values of the hidden type ever being constructed,
@@ -273,6 +269,7 @@ pub(super) fn find_opaque_ty_constraints_for_rpit<'tcx>(
                     if let Err(guar) = hir_ty.error_reported() {
                         Ty::new_error(tcx, guar)
                     } else {
+                        assert!(!tcx.next_trait_solver_globally());
                         hir_ty
                     }
                 }
diff --git a/compiler/rustc_hir_analysis/src/errors.rs b/compiler/rustc_hir_analysis/src/errors.rs
index 26a98722b34..6565ad7cf53 100644
--- a/compiler/rustc_hir_analysis/src/errors.rs
+++ b/compiler/rustc_hir_analysis/src/errors.rs
@@ -410,17 +410,6 @@ pub(crate) struct UnconstrainedOpaqueType {
     pub what: &'static str,
 }
 
-#[derive(Diagnostic)]
-#[diag(hir_analysis_tait_forward_compat2)]
-#[note]
-pub(crate) struct TaitForwardCompat2 {
-    #[primary_span]
-    pub span: Span,
-    #[note(hir_analysis_opaque)]
-    pub opaque_type_span: Span,
-    pub opaque_type: String,
-}
-
 pub(crate) struct MissingTypeParams {
     pub span: Span,
     pub def_span: Span,
diff --git a/compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs b/compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs
index 0043f0c7117..b38639ed8c6 100644
--- a/compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs
+++ b/compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs
@@ -390,45 +390,13 @@ fn check_predicates<'tcx>(
 
     let mut res = Ok(());
     for (clause, span) in impl1_predicates {
-        if !impl2_predicates.iter().any(|pred2| trait_predicates_eq(clause.as_predicate(), *pred2))
-        {
+        if !impl2_predicates.iter().any(|&pred2| clause.as_predicate() == pred2) {
             res = res.and(check_specialization_on(tcx, clause, span))
         }
     }
     res
 }
 
-/// Checks if some predicate on the specializing impl (`predicate1`) is the same
-/// as some predicate on the base impl (`predicate2`).
-///
-/// This basically just checks syntactic equivalence, but is a little more
-/// forgiving since we want to equate `T: Tr` with `T: [const] Tr` so this can work:
-///
-/// ```ignore (illustrative)
-/// #[rustc_specialization_trait]
-/// trait Specialize { }
-///
-/// impl<T: Bound> Tr for T { }
-/// impl<T: [const] Bound + Specialize> const Tr for T { }
-/// ```
-///
-/// However, we *don't* want to allow the reverse, i.e., when the bound on the
-/// specializing impl is not as const as the bound on the base impl:
-///
-/// ```ignore (illustrative)
-/// impl<T: [const] Bound> const Tr for T { }
-/// impl<T: Bound + Specialize> const Tr for T { } // should be T: [const] Bound
-/// ```
-///
-/// So we make that check in this function and try to raise a helpful error message.
-fn trait_predicates_eq<'tcx>(
-    predicate1: ty::Predicate<'tcx>,
-    predicate2: ty::Predicate<'tcx>,
-) -> bool {
-    // FIXME(const_trait_impl)
-    predicate1 == predicate2
-}
-
 #[instrument(level = "debug", skip(tcx))]
 fn check_specialization_on<'tcx>(
     tcx: TyCtxt<'tcx>,
diff --git a/compiler/rustc_hir_analysis/src/lib.rs b/compiler/rustc_hir_analysis/src/lib.rs
index 3a153ab089a..44a5ceed469 100644
--- a/compiler/rustc_hir_analysis/src/lib.rs
+++ b/compiler/rustc_hir_analysis/src/lib.rs
@@ -82,7 +82,7 @@ mod coherence;
 mod collect;
 mod constrained_generic_params;
 mod delegation;
-mod errors;
+pub mod errors;
 pub mod hir_ty_lowering;
 pub mod hir_wf_check;
 mod impl_wf_check;
diff --git a/compiler/rustc_hir_id/Cargo.toml b/compiler/rustc_hir_id/Cargo.toml
new file mode 100644
index 00000000000..c357a4f62d9
--- /dev/null
+++ b/compiler/rustc_hir_id/Cargo.toml
@@ -0,0 +1,13 @@
+[package]
+name = "rustc_hir_id"
+version = "0.0.0"
+edition = "2024"
+
+[dependencies]
+# tidy-alphabetical-start
+rustc_data_structures = { path = "../rustc_data_structures" }
+rustc_index = { path = "../rustc_index" }
+rustc_macros = { path = "../rustc_macros" }
+rustc_serialize = { path = "../rustc_serialize" }
+rustc_span = { path = "../rustc_span" }
+# tidy-alphabetical-end
diff --git a/compiler/rustc_hir/src/hir_id.rs b/compiler/rustc_hir_id/src/lib.rs
index b48a081d371..d07bc88e66a 100644
--- a/compiler/rustc_hir/src/hir_id.rs
+++ b/compiler/rustc_hir_id/src/lib.rs
@@ -1,11 +1,15 @@
+//! Library containing Id types from `rustc_hir`, split out so crates can use it without depending
+//! on all of `rustc_hir` (which is large and depends on other large things like `rustc_target`).
+#![allow(internal_features)]
+#![feature(negative_impls)]
+#![feature(rustc_attrs)]
+
 use std::fmt::{self, Debug};
 
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, StableOrd, ToStableHashKey};
 use rustc_macros::{Decodable, Encodable, HashStable_Generic};
-use rustc_span::HashStableContext;
-use rustc_span::def_id::DefPathHash;
-
-use crate::def_id::{CRATE_DEF_ID, DefId, DefIndex, LocalDefId};
+pub use rustc_span::HashStableContext;
+use rustc_span::def_id::{CRATE_DEF_ID, DefId, DefIndex, DefPathHash, LocalDefId};
 
 #[derive(Copy, Clone, PartialEq, Eq, Hash, Encodable, Decodable)]
 pub struct OwnerId {
@@ -171,3 +175,22 @@ pub const CRATE_HIR_ID: HirId =
     HirId { owner: OwnerId { def_id: CRATE_DEF_ID }, local_id: ItemLocalId::ZERO };
 
 pub const CRATE_OWNER_ID: OwnerId = OwnerId { def_id: CRATE_DEF_ID };
+
+impl<CTX: rustc_span::HashStableContext> ToStableHashKey<CTX> for HirId {
+    type KeyType = (DefPathHash, ItemLocalId);
+
+    #[inline]
+    fn to_stable_hash_key(&self, hcx: &CTX) -> (DefPathHash, ItemLocalId) {
+        let def_path_hash = self.owner.def_id.to_stable_hash_key(hcx);
+        (def_path_hash, self.local_id)
+    }
+}
+
+impl<CTX: HashStableContext> ToStableHashKey<CTX> for ItemLocalId {
+    type KeyType = ItemLocalId;
+
+    #[inline]
+    fn to_stable_hash_key(&self, _: &CTX) -> ItemLocalId {
+        *self
+    }
+}
diff --git a/compiler/rustc_hir_typeck/Cargo.toml b/compiler/rustc_hir_typeck/Cargo.toml
index f00125c3e09..5af0c6134ca 100644
--- a/compiler/rustc_hir_typeck/Cargo.toml
+++ b/compiler/rustc_hir_typeck/Cargo.toml
@@ -5,7 +5,7 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-itertools = "0.12"
+itertools.workspace = true
 rustc_abi = { path = "../rustc_abi" }
 rustc_ast = { path = "../rustc_ast" }
 rustc_attr_parsing = { path = "../rustc_attr_parsing" }
@@ -25,5 +25,5 @@ rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 rustc_trait_selection = { path = "../rustc_trait_selection" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_hir_typeck/src/callee.rs b/compiler/rustc_hir_typeck/src/callee.rs
index 48bb45de53e..4200afb74e6 100644
--- a/compiler/rustc_hir_typeck/src/callee.rs
+++ b/compiler/rustc_hir_typeck/src/callee.rs
@@ -511,7 +511,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 // Untranslatable diagnostics are okay for rustc internals
                 #[allow(rustc::untranslatable_diagnostic)]
                 #[allow(rustc::diagnostic_outside_of_impl)]
-                if self.tcx.has_attr(def_id, sym::rustc_evaluate_where_clauses) {
+                if self.has_rustc_attrs
+                    && self.tcx.has_attr(def_id, sym::rustc_evaluate_where_clauses)
+                {
                     let predicates = self.tcx.predicates_of(def_id);
                     let predicates = predicates.instantiate(self.tcx, args);
                     for (predicate, predicate_span) in predicates {
@@ -894,7 +896,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
 
         // If we have `rustc_do_not_const_check`, do not check `[const]` bounds.
-        if self.tcx.has_attr(self.body_id, sym::rustc_do_not_const_check) {
+        if self.has_rustc_attrs && self.tcx.has_attr(self.body_id, sym::rustc_do_not_const_check) {
             return;
         }
 
@@ -910,7 +912,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // const stability checking here too, I guess.
         if self.tcx.is_conditionally_const(callee_did) {
             let q = self.tcx.const_conditions(callee_did);
-            // FIXME(const_trait_impl): Use this span with a better cause code.
             for (idx, (cond, pred_span)) in
                 q.instantiate(self.tcx, callee_args).into_iter().enumerate()
             {
diff --git a/compiler/rustc_hir_typeck/src/expr.rs b/compiler/rustc_hir_typeck/src/expr.rs
index 0498a938366..940f0e3708d 100644
--- a/compiler/rustc_hir_typeck/src/expr.rs
+++ b/compiler/rustc_hir_typeck/src/expr.rs
@@ -290,6 +290,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             | ExprKind::Let(..)
             | ExprKind::Loop(..)
             | ExprKind::Match(..) => {}
+            // Do not warn on `as` casts from never to any,
+            // they are sometimes required to appeal typeck.
+            ExprKind::Cast(_, _) => {}
             // If `expr` is a result of desugaring the try block and is an ok-wrapped
             // diverging expression (e.g. it arose from desugaring of `try { return }`),
             // we skip issuing a warning because it is autogenerated code.
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
index b80a2af3100..5aec50c8b53 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
@@ -83,14 +83,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         *self.deferred_cast_checks.borrow_mut() = deferred_cast_checks;
     }
 
-    pub(in super::super) fn check_transmutes(&self) {
-        let mut deferred_transmute_checks = self.deferred_transmute_checks.borrow_mut();
-        debug!("FnCtxt::check_transmutes: {} deferred checks", deferred_transmute_checks.len());
-        for (from, to, hir_id) in deferred_transmute_checks.drain(..) {
-            self.check_transmute(from, to, hir_id);
-        }
-    }
-
     pub(in super::super) fn check_asms(&self) {
         let mut deferred_asm_checks = self.deferred_asm_checks.borrow_mut();
         debug!("FnCtxt::check_asm: {} deferred checks", deferred_asm_checks.len());
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
index 0c6226ce71e..74f27e85cba 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
@@ -126,6 +126,10 @@ pub(crate) struct FnCtxt<'a, 'tcx> {
     /// These are stored here so we may collect them when canonicalizing user
     /// type ascriptions later.
     pub(super) trait_ascriptions: RefCell<ItemLocalMap<Vec<ty::Clause<'tcx>>>>,
+
+    /// Whether the current crate enables the `rustc_attrs` feature.
+    /// This allows to skip processing attributes in many places.
+    pub(super) has_rustc_attrs: bool,
 }
 
 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
@@ -154,6 +158,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             diverging_fallback_behavior,
             diverging_block_behavior,
             trait_ascriptions: Default::default(),
+            has_rustc_attrs: root_ctxt.tcx.features().rustc_attrs(),
         }
     }
 
@@ -525,10 +530,13 @@ fn parse_never_type_options_attr(
     let mut fallback = None;
     let mut block = None;
 
-    let items = tcx
-        .get_attr(CRATE_DEF_ID, sym::rustc_never_type_options)
-        .map(|attr| attr.meta_item_list().unwrap())
-        .unwrap_or_default();
+    let items = if tcx.features().rustc_attrs() {
+        tcx.get_attr(CRATE_DEF_ID, sym::rustc_never_type_options)
+            .map(|attr| attr.meta_item_list().unwrap())
+    } else {
+        None
+    };
+    let items = items.unwrap_or_default();
 
     for item in items {
         if item.has_name(sym::fallback) && fallback.is_none() {
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs
index 6013430e1ff..aca3840712e 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs
@@ -2378,6 +2378,15 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 .filter_map(|variant| {
                     let sole_field = &variant.single_field();
 
+                    // When expected_ty and expr_ty are the same ADT, we prefer to compare their internal generic params,
+                    // When the current variant has a sole field whose type is still an unresolved inference variable,
+                    // suggestions would be often wrong. So suppress the suggestion. See #145294.
+                    if let (ty::Adt(exp_adt, _), ty::Adt(act_adt, _)) = (expected.kind(), expr_ty.kind())
+                        && exp_adt.did() == act_adt.did()
+                        && sole_field.ty(self.tcx, args).is_ty_var() {
+                            return None;
+                    }
+
                     let field_is_local = sole_field.did.is_local();
                     let field_is_accessible =
                         sole_field.vis.is_accessible_from(expr.hir_id.owner.def_id, self.tcx)
diff --git a/compiler/rustc_hir_typeck/src/intrinsicck.rs b/compiler/rustc_hir_typeck/src/intrinsicck.rs
index 194e420b606..7567f8ba348 100644
--- a/compiler/rustc_hir_typeck/src/intrinsicck.rs
+++ b/compiler/rustc_hir_typeck/src/intrinsicck.rs
@@ -7,11 +7,10 @@ use rustc_hir as hir;
 use rustc_index::Idx;
 use rustc_middle::bug;
 use rustc_middle::ty::layout::{LayoutError, SizeSkeleton};
-use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitableExt};
+use rustc_middle::ty::{self, Ty, TyCtxt};
+use rustc_span::def_id::LocalDefId;
 use tracing::trace;
 
-use super::FnCtxt;
-
 /// If the type is `Option<T>`, it will return `T`, otherwise
 /// the type itself. Works on most `Option`-like types.
 fn unpack_option_like<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Ty<'tcx> {
@@ -39,119 +38,117 @@ fn unpack_option_like<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Ty<'tcx> {
     ty
 }
 
-impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
-    /// FIXME: Move this check out of typeck, since it'll easily cycle when revealing opaques,
-    /// and we shouldn't need to check anything here if the typeck results are tainted.
-    pub(crate) fn check_transmute(&self, from: Ty<'tcx>, to: Ty<'tcx>, hir_id: HirId) {
-        let tcx = self.tcx;
-        let dl = &tcx.data_layout;
-        let span = tcx.hir_span(hir_id);
-        let normalize = |ty| {
-            let ty = self.resolve_vars_if_possible(ty);
-            if let Ok(ty) =
-                self.tcx.try_normalize_erasing_regions(self.typing_env(self.param_env), ty)
-            {
-                ty
+/// Try to display a sensible error with as much information as possible.
+fn skeleton_string<'tcx>(
+    ty: Ty<'tcx>,
+    sk: Result<SizeSkeleton<'tcx>, &'tcx LayoutError<'tcx>>,
+) -> String {
+    match sk {
+        Ok(SizeSkeleton::Pointer { tail, .. }) => format!("pointer to `{tail}`"),
+        Ok(SizeSkeleton::Known(size, _)) => {
+            if let Some(v) = u128::from(size.bytes()).checked_mul(8) {
+                format!("{v} bits")
             } else {
-                Ty::new_error_with_message(
-                    tcx,
-                    span,
-                    "tried to normalize non-wf type in check_transmute",
-                )
+                // `u128` should definitely be able to hold the size of different architectures
+                // larger sizes should be reported as error `are too big for the target architecture`
+                // otherwise we have a bug somewhere
+                bug!("{:?} overflow for u128", size)
             }
-        };
-        let from = normalize(from);
-        let to = normalize(to);
-        trace!(?from, ?to);
-        if from.has_non_region_infer() || to.has_non_region_infer() {
-            // Note: this path is currently not reached in any test, so any
-            // example that triggers this would be worth minimizing and
-            // converting into a test.
-            self.dcx().span_bug(span, "argument to transmute has inference variables");
         }
-        // Transmutes that are only changing lifetimes are always ok.
-        if from == to {
-            return;
+        Ok(SizeSkeleton::Generic(size)) => {
+            format!("generic size {size}")
+        }
+        Err(LayoutError::TooGeneric(bad)) => {
+            if *bad == ty {
+                "this type does not have a fixed size".to_owned()
+            } else {
+                format!("size can vary because of {bad}")
+            }
+        }
+        Err(err) => err.to_string(),
+    }
+}
+
+fn check_transmute<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    typing_env: ty::TypingEnv<'tcx>,
+    from: Ty<'tcx>,
+    to: Ty<'tcx>,
+    hir_id: HirId,
+) {
+    let span = || tcx.hir_span(hir_id);
+    let normalize = |ty| {
+        if let Ok(ty) = tcx.try_normalize_erasing_regions(typing_env, ty) {
+            ty
+        } else {
+            Ty::new_error_with_message(
+                tcx,
+                span(),
+                format!("tried to normalize non-wf type {ty:#?} in check_transmute"),
+            )
         }
+    };
 
-        let skel = |ty| SizeSkeleton::compute(ty, tcx, self.typing_env(self.param_env));
-        let sk_from = skel(from);
-        let sk_to = skel(to);
-        trace!(?sk_from, ?sk_to);
+    let from = normalize(from);
+    let to = normalize(to);
+    trace!(?from, ?to);
 
-        // Check for same size using the skeletons.
-        if let (Ok(sk_from), Ok(sk_to)) = (sk_from, sk_to) {
-            if sk_from.same_size(sk_to) {
-                return;
-            }
+    // Transmutes that are only changing lifetimes are always ok.
+    if from == to {
+        return;
+    }
 
-            // Special-case transmuting from `typeof(function)` and
-            // `Option<typeof(function)>` to present a clearer error.
-            let from = unpack_option_like(tcx, from);
-            if let (&ty::FnDef(..), SizeSkeleton::Known(size_to, _)) = (from.kind(), sk_to)
-                && size_to == Pointer(dl.instruction_address_space).size(&tcx)
-            {
-                struct_span_code_err!(self.dcx(), span, E0591, "can't transmute zero-sized type")
-                    .with_note(format!("source type: {from}"))
-                    .with_note(format!("target type: {to}"))
-                    .with_help("cast with `as` to a pointer instead")
-                    .emit();
-                return;
-            }
+    let sk_from = SizeSkeleton::compute(from, tcx, typing_env);
+    let sk_to = SizeSkeleton::compute(to, tcx, typing_env);
+    trace!(?sk_from, ?sk_to);
+
+    // Check for same size using the skeletons.
+    if let Ok(sk_from) = sk_from
+        && let Ok(sk_to) = sk_to
+    {
+        if sk_from.same_size(sk_to) {
+            return;
         }
 
-        // Try to display a sensible error with as much information as possible.
-        let skeleton_string = |ty: Ty<'tcx>, sk: Result<_, &_>| match sk {
-            Ok(SizeSkeleton::Pointer { tail, .. }) => format!("pointer to `{tail}`"),
-            Ok(SizeSkeleton::Known(size, _)) => {
-                if let Some(v) = u128::from(size.bytes()).checked_mul(8) {
-                    format!("{v} bits")
-                } else {
-                    // `u128` should definitely be able to hold the size of different architectures
-                    // larger sizes should be reported as error `are too big for the target architecture`
-                    // otherwise we have a bug somewhere
-                    bug!("{:?} overflow for u128", size)
-                }
-            }
-            Ok(SizeSkeleton::Generic(size)) => {
-                if let Some(size) =
-                    self.try_structurally_resolve_const(span, size).try_to_target_usize(tcx)
-                {
-                    format!("{size} bytes")
-                } else {
-                    format!("generic size {size}")
-                }
-            }
-            Err(LayoutError::TooGeneric(bad)) => {
-                if *bad == ty {
-                    "this type does not have a fixed size".to_owned()
-                } else {
-                    format!("size can vary because of {bad}")
-                }
-            }
-            Err(err) => err.to_string(),
-        };
-
-        let mut err = struct_span_code_err!(
-            self.dcx(),
-            span,
-            E0512,
-            "cannot transmute between types of different sizes, \
-                                        or dependently-sized types"
-        );
-        if from == to {
-            err.note(format!("`{from}` does not have a fixed size"));
-            err.emit();
-        } else {
-            err.note(format!("source type: `{}` ({})", from, skeleton_string(from, sk_from)))
-                .note(format!("target type: `{}` ({})", to, skeleton_string(to, sk_to)));
-            if let Err(LayoutError::ReferencesError(_)) = sk_from {
-                err.delay_as_bug();
-            } else if let Err(LayoutError::ReferencesError(_)) = sk_to {
-                err.delay_as_bug();
-            } else {
-                err.emit();
-            }
+        // Special-case transmuting from `typeof(function)` and
+        // `Option<typeof(function)>` to present a clearer error.
+        let from = unpack_option_like(tcx, from);
+        if let ty::FnDef(..) = from.kind()
+            && let SizeSkeleton::Known(size_to, _) = sk_to
+            && size_to == Pointer(tcx.data_layout.instruction_address_space).size(&tcx)
+        {
+            struct_span_code_err!(tcx.sess.dcx(), span(), E0591, "can't transmute zero-sized type")
+                .with_note(format!("source type: {from}"))
+                .with_note(format!("target type: {to}"))
+                .with_help("cast with `as` to a pointer instead")
+                .emit();
+            return;
         }
     }
+
+    let mut err = struct_span_code_err!(
+        tcx.sess.dcx(),
+        span(),
+        E0512,
+        "cannot transmute between types of different sizes, or dependently-sized types"
+    );
+    if from == to {
+        err.note(format!("`{from}` does not have a fixed size"));
+        err.emit();
+    } else {
+        err.note(format!("source type: `{}` ({})", from, skeleton_string(from, sk_from)));
+        err.note(format!("target type: `{}` ({})", to, skeleton_string(to, sk_to)));
+        err.emit();
+    }
+}
+
+pub(crate) fn check_transmutes(tcx: TyCtxt<'_>, owner: LocalDefId) {
+    assert!(!tcx.is_typeck_child(owner.to_def_id()));
+    let typeck_results = tcx.typeck(owner);
+    let None = typeck_results.tainted_by_errors else { return };
+
+    let typing_env = ty::TypingEnv::post_analysis(tcx, owner);
+    for &(from, to, hir_id) in &typeck_results.transmutes_to_check {
+        check_transmute(tcx, typing_env, from, to, hir_id);
+    }
 }
diff --git a/compiler/rustc_hir_typeck/src/lib.rs b/compiler/rustc_hir_typeck/src/lib.rs
index aae870f7ee3..129de32fd4a 100644
--- a/compiler/rustc_hir_typeck/src/lib.rs
+++ b/compiler/rustc_hir_typeck/src/lib.rs
@@ -46,14 +46,14 @@ use rustc_data_structures::unord::UnordSet;
 use rustc_errors::codes::*;
 use rustc_errors::{Applicability, ErrorGuaranteed, pluralize, struct_span_code_err};
 use rustc_hir as hir;
-use rustc_hir::attrs::AttributeKind;
 use rustc_hir::def::{DefKind, Res};
-use rustc_hir::{HirId, HirIdMap, Node, find_attr};
+use rustc_hir::{HirId, HirIdMap, Node};
 use rustc_hir_analysis::check::{check_abi, check_custom_abi};
 use rustc_hir_analysis::hir_ty_lowering::HirTyLowerer;
 use rustc_infer::traits::{ObligationCauseCode, ObligationInspector, WellFormedLoc};
+use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc_middle::query::Providers;
-use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitableExt};
+use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_middle::{bug, span_bug};
 use rustc_session::config;
 use rustc_span::Span;
@@ -174,7 +174,7 @@ fn typeck_with_inspect<'tcx>(
                 .map(|(idx, ty)| fcx.normalize(arg_span(idx), ty)),
         );
 
-        if find_attr!(tcx.get_all_attrs(def_id), AttributeKind::Naked(..)) {
+        if tcx.codegen_fn_attrs(def_id).flags.contains(CodegenFnAttrFlags::NAKED) {
             naked_functions::typeck_naked_fn(tcx, def_id, body);
         }
 
@@ -247,33 +247,21 @@ fn typeck_with_inspect<'tcx>(
 
     debug!(pending_obligations = ?fcx.fulfillment_cx.borrow().pending_obligations());
 
-    if let None = fcx.infcx.tainted_by_errors() {
-        fcx.report_ambiguity_errors();
+    // We need to handle opaque types before emitting ambiguity errors as applying
+    // defining uses may guide type inference.
+    if fcx.next_trait_solver() {
+        fcx.handle_opaque_type_uses_next();
     }
 
+    fcx.select_obligations_where_possible(|_| {});
     if let None = fcx.infcx.tainted_by_errors() {
-        fcx.check_transmutes();
+        fcx.report_ambiguity_errors();
     }
 
     fcx.check_asms();
 
     let typeck_results = fcx.resolve_type_vars_in_body(body);
 
-    // Handle potentially region dependent goals, see `InferCtxt::in_hir_typeck`.
-    if let None = fcx.infcx.tainted_by_errors() {
-        for obligation in fcx.take_hir_typeck_potentially_region_dependent_goals() {
-            let obligation = fcx.resolve_vars_if_possible(obligation);
-            if obligation.has_non_region_infer() {
-                bug!("unexpected inference variable after writeback: {obligation:?}");
-            }
-            fcx.register_predicate(obligation);
-        }
-        fcx.select_obligations_where_possible(|_| {});
-        if let None = fcx.infcx.tainted_by_errors() {
-            fcx.report_ambiguity_errors();
-        }
-    }
-
     fcx.detect_opaque_types_added_during_writeback();
 
     // Consistency check our TypeckResults instance can hold all ItemLocalIds
@@ -555,6 +543,7 @@ pub fn provide(providers: &mut Providers) {
         method_autoderef_steps: method::probe::method_autoderef_steps,
         typeck,
         used_trait_imports,
+        check_transmutes: intrinsicck::check_transmutes,
         ..*providers
     };
 }
diff --git a/compiler/rustc_hir_typeck/src/method/probe.rs b/compiler/rustc_hir_typeck/src/method/probe.rs
index 3ca3b56b87e..bb4748b0565 100644
--- a/compiler/rustc_hir_typeck/src/method/probe.rs
+++ b/compiler/rustc_hir_typeck/src/method/probe.rs
@@ -777,31 +777,16 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
 
                 self.assemble_inherent_candidates_from_object(generalized_self_ty);
                 self.assemble_inherent_impl_candidates_for_type(p.def_id(), receiver_steps);
-                if self.tcx.has_attr(p.def_id(), sym::rustc_has_incoherent_inherent_impls) {
-                    self.assemble_inherent_candidates_for_incoherent_ty(
-                        raw_self_ty,
-                        receiver_steps,
-                    );
-                }
+                self.assemble_inherent_candidates_for_incoherent_ty(raw_self_ty, receiver_steps);
             }
             ty::Adt(def, _) => {
                 let def_id = def.did();
                 self.assemble_inherent_impl_candidates_for_type(def_id, receiver_steps);
-                if self.tcx.has_attr(def_id, sym::rustc_has_incoherent_inherent_impls) {
-                    self.assemble_inherent_candidates_for_incoherent_ty(
-                        raw_self_ty,
-                        receiver_steps,
-                    );
-                }
+                self.assemble_inherent_candidates_for_incoherent_ty(raw_self_ty, receiver_steps);
             }
             ty::Foreign(did) => {
                 self.assemble_inherent_impl_candidates_for_type(did, receiver_steps);
-                if self.tcx.has_attr(did, sym::rustc_has_incoherent_inherent_impls) {
-                    self.assemble_inherent_candidates_for_incoherent_ty(
-                        raw_self_ty,
-                        receiver_steps,
-                    );
-                }
+                self.assemble_inherent_candidates_for_incoherent_ty(raw_self_ty, receiver_steps);
             }
             ty::Param(_) => {
                 self.assemble_inherent_candidates_from_param(raw_self_ty);
@@ -909,6 +894,10 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         debug_assert_matches!(param_ty.kind(), ty::Param(_));
 
         let tcx = self.tcx;
+
+        // We use `DeepRejectCtxt` here which may return false positive on where clauses
+        // with alias self types. We need to later on reject these as inherent candidates
+        // in `consider_probe`.
         let bounds = self.param_env.caller_bounds().iter().filter_map(|predicate| {
             let bound_predicate = predicate.kind();
             match bound_predicate.skip_binder() {
@@ -1945,6 +1934,29 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                     );
                     (xform_self_ty, xform_ret_ty) =
                         self.xform_self_ty(probe.item, trait_ref.self_ty(), trait_ref.args);
+
+                    if matches!(probe.kind, WhereClauseCandidate(_)) {
+                        // `WhereClauseCandidate` requires that the self type is a param,
+                        // because it has special behavior with candidate preference as an
+                        // inherent pick.
+                        match ocx.structurally_normalize_ty(
+                            cause,
+                            self.param_env,
+                            trait_ref.self_ty(),
+                        ) {
+                            Ok(ty) => {
+                                if !matches!(ty.kind(), ty::Param(_)) {
+                                    debug!("--> not a param ty: {xform_self_ty:?}");
+                                    return ProbeResult::NoMatch;
+                                }
+                            }
+                            Err(errors) => {
+                                debug!("--> cannot relate self-types {:?}", errors);
+                                return ProbeResult::NoMatch;
+                            }
+                        }
+                    }
+
                     xform_self_ty = ocx.normalize(cause, self.param_env, xform_self_ty);
                     match ocx.relate(cause, self.param_env, self.variance(), self_ty, xform_self_ty)
                     {
@@ -2373,17 +2385,14 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                         if !self.is_relevant_kind_for_mode(x.kind) {
                             return false;
                         }
-                        if self.matches_by_doc_alias(x.def_id) {
-                            return true;
-                        }
-                        match edit_distance_with_substrings(
+                        if let Some(d) = edit_distance_with_substrings(
                             name.as_str(),
                             x.name().as_str(),
                             max_dist,
                         ) {
-                            Some(d) => d > 0,
-                            None => false,
+                            return d > 0;
                         }
+                        self.matches_by_doc_alias(x.def_id)
                     })
                     .copied()
                     .collect()
diff --git a/compiler/rustc_hir_typeck/src/method/suggest.rs b/compiler/rustc_hir_typeck/src/method/suggest.rs
index 824d592fa6c..c8f6c06b720 100644
--- a/compiler/rustc_hir_typeck/src/method/suggest.rs
+++ b/compiler/rustc_hir_typeck/src/method/suggest.rs
@@ -13,9 +13,7 @@ use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
 use rustc_data_structures::sorted_map::SortedMap;
 use rustc_data_structures::unord::UnordSet;
 use rustc_errors::codes::*;
-use rustc_errors::{
-    Applicability, Diag, DiagStyledString, MultiSpan, StashKey, pluralize, struct_span_code_err,
-};
+use rustc_errors::{Applicability, Diag, MultiSpan, StashKey, pluralize, struct_span_code_err};
 use rustc_hir::attrs::AttributeKind;
 use rustc_hir::def::{CtorKind, DefKind, Res};
 use rustc_hir::def_id::DefId;
@@ -1560,11 +1558,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             );
         }
 
-        if rcvr_ty.is_numeric() && rcvr_ty.is_fresh()
-            || restrict_type_params
-            || suggested_derive
-            || self.lookup_alternative_tuple_impls(&mut err, &unsatisfied_predicates)
-        {
+        if rcvr_ty.is_numeric() && rcvr_ty.is_fresh() || restrict_type_params || suggested_derive {
         } else {
             self.suggest_traits_to_import(
                 &mut err,
@@ -1741,119 +1735,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         err.emit()
     }
 
-    /// If the predicate failure is caused by an unmet bound on a tuple, recheck if the bound would
-    /// succeed if all the types on the tuple had no borrows. This is a common problem for libraries
-    /// like Bevy and ORMs, which rely heavily on traits being implemented on tuples.
-    fn lookup_alternative_tuple_impls(
-        &self,
-        err: &mut Diag<'_>,
-        unsatisfied_predicates: &[(
-            ty::Predicate<'tcx>,
-            Option<ty::Predicate<'tcx>>,
-            Option<ObligationCause<'tcx>>,
-        )],
-    ) -> bool {
-        let mut found_tuple = false;
-        for (pred, root, _ob) in unsatisfied_predicates {
-            let mut preds = vec![pred];
-            if let Some(root) = root {
-                // We will look at both the current predicate and the root predicate that caused it
-                // to be needed. If calling something like `<(A, &B)>::default()`, then `pred` is
-                // `&B: Default` and `root` is `(A, &B): Default`, which is the one we are checking
-                // for further down, so we check both.
-                preds.push(root);
-            }
-            for pred in preds {
-                if let Some(clause) = pred.as_clause()
-                    && let Some(clause) = clause.as_trait_clause()
-                    && let ty = clause.self_ty().skip_binder()
-                    && let ty::Tuple(types) = ty.kind()
-                {
-                    let path = clause.skip_binder().trait_ref.print_only_trait_path();
-                    let def_id = clause.def_id();
-                    let ty = Ty::new_tup(
-                        self.tcx,
-                        self.tcx.mk_type_list_from_iter(types.iter().map(|ty| ty.peel_refs())),
-                    );
-                    let args = ty::GenericArgs::for_item(self.tcx, def_id, |param, _| {
-                        if param.index == 0 {
-                            ty.into()
-                        } else {
-                            self.infcx.var_for_def(DUMMY_SP, param)
-                        }
-                    });
-                    if self
-                        .infcx
-                        .type_implements_trait(def_id, args, self.param_env)
-                        .must_apply_modulo_regions()
-                    {
-                        // "`Trait` is implemented for `(A, B)` but not for `(A, &B)`"
-                        let mut msg = DiagStyledString::normal(format!("`{path}` "));
-                        msg.push_highlighted("is");
-                        msg.push_normal(" implemented for `(");
-                        let len = types.len();
-                        for (i, t) in types.iter().enumerate() {
-                            msg.push(
-                                format!("{}", with_forced_trimmed_paths!(t.peel_refs())),
-                                t.peel_refs() != t,
-                            );
-                            if i < len - 1 {
-                                msg.push_normal(", ");
-                            }
-                        }
-                        msg.push_normal(")` but ");
-                        msg.push_highlighted("not");
-                        msg.push_normal(" for `(");
-                        for (i, t) in types.iter().enumerate() {
-                            msg.push(
-                                format!("{}", with_forced_trimmed_paths!(t)),
-                                t.peel_refs() != t,
-                            );
-                            if i < len - 1 {
-                                msg.push_normal(", ");
-                            }
-                        }
-                        msg.push_normal(")`");
-
-                        // Find the span corresponding to the impl that was found to point at it.
-                        if let Some(impl_span) = self
-                            .tcx
-                            .all_impls(def_id)
-                            .filter(|&impl_def_id| {
-                                let header = self.tcx.impl_trait_header(impl_def_id).unwrap();
-                                let trait_ref = header.trait_ref.instantiate(
-                                    self.tcx,
-                                    self.infcx.fresh_args_for_item(DUMMY_SP, impl_def_id),
-                                );
-
-                                let value = ty::fold_regions(self.tcx, ty, |_, _| {
-                                    self.tcx.lifetimes.re_erased
-                                });
-                                // FIXME: Don't bother dealing with non-lifetime binders here...
-                                if value.has_escaping_bound_vars() {
-                                    return false;
-                                }
-                                self.infcx.can_eq(ty::ParamEnv::empty(), trait_ref.self_ty(), value)
-                                    && header.polarity == ty::ImplPolarity::Positive
-                            })
-                            .map(|impl_def_id| self.tcx.def_span(impl_def_id))
-                            .next()
-                        {
-                            err.highlighted_span_note(impl_span, msg.0);
-                        } else {
-                            err.highlighted_note(msg.0);
-                        }
-                        found_tuple = true;
-                    }
-                    // If `pred` was already on the tuple, we don't need to look at the root
-                    // obligation too.
-                    break;
-                }
-            }
-        }
-        found_tuple
-    }
-
     /// If an appropriate error source is not found, check method chain for possible candidates
     fn lookup_segments_chain_for_no_match_method(
         &self,
diff --git a/compiler/rustc_hir_typeck/src/opaque_types.rs b/compiler/rustc_hir_typeck/src/opaque_types.rs
index e0224f8c6e1..97feac3d009 100644
--- a/compiler/rustc_hir_typeck/src/opaque_types.rs
+++ b/compiler/rustc_hir_typeck/src/opaque_types.rs
@@ -1,5 +1,218 @@
-use super::FnCtxt;
+use rustc_hir::def::DefKind;
+use rustc_infer::traits::ObligationCause;
+use rustc_middle::ty::{
+    self, DefiningScopeKind, EarlyBinder, OpaqueHiddenType, OpaqueTypeKey, TypeVisitableExt,
+    TypingMode,
+};
+use rustc_trait_selection::error_reporting::infer::need_type_info::TypeAnnotationNeeded;
+use rustc_trait_selection::opaque_types::{
+    NonDefiningUseReason, opaque_type_has_defining_use_args, report_item_does_not_constrain_error,
+};
+use rustc_trait_selection::solve;
+use tracing::{debug, instrument};
+
+use crate::FnCtxt;
+
 impl<'tcx> FnCtxt<'_, 'tcx> {
+    /// This takes all the opaque type uses during HIR typeck. It first computes
+    /// the concrete hidden type by iterating over all defining uses.
+    ///
+    /// A use during HIR typeck is defining if all non-lifetime arguments are
+    /// unique generic parameters and the hidden type does not reference any
+    /// inference variables.
+    ///
+    /// It then uses these defining uses to guide inference for all other uses.
+    #[instrument(level = "debug", skip(self))]
+    pub(super) fn handle_opaque_type_uses_next(&mut self) {
+        // We clone the opaques instead of stealing them here as they are still used for
+        // normalization in the next generation trait solver.
+        let mut opaque_types: Vec<_> = self.infcx.clone_opaque_types();
+        let num_entries = self.inner.borrow_mut().opaque_types().num_entries();
+        let prev = self.checked_opaque_types_storage_entries.replace(Some(num_entries));
+        debug_assert_eq!(prev, None);
+        for entry in &mut opaque_types {
+            *entry = self.resolve_vars_if_possible(*entry);
+        }
+        debug!(?opaque_types);
+
+        self.compute_concrete_opaque_types(&opaque_types);
+        self.apply_computed_concrete_opaque_types(&opaque_types);
+    }
+}
+
+enum UsageKind<'tcx> {
+    None,
+    NonDefiningUse(OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>),
+    UnconstrainedHiddenType(OpaqueHiddenType<'tcx>),
+    HasDefiningUse,
+}
+
+impl<'tcx> UsageKind<'tcx> {
+    fn merge(&mut self, other: UsageKind<'tcx>) {
+        match (&*self, &other) {
+            (UsageKind::HasDefiningUse, _) | (_, UsageKind::None) => unreachable!(),
+            (UsageKind::None, _) => *self = other,
+            // When mergining non-defining uses, prefer earlier ones. This means
+            // the error happens as early as possible.
+            (
+                UsageKind::NonDefiningUse(..) | UsageKind::UnconstrainedHiddenType(..),
+                UsageKind::NonDefiningUse(..),
+            ) => {}
+            // When merging unconstrained hidden types, we prefer later ones. This is
+            // used as in most cases, the defining use is the final return statement
+            // of our function, and other uses with defining arguments are likely not
+            // intended to be defining.
+            (
+                UsageKind::NonDefiningUse(..) | UsageKind::UnconstrainedHiddenType(..),
+                UsageKind::UnconstrainedHiddenType(..) | UsageKind::HasDefiningUse,
+            ) => *self = other,
+        }
+    }
+}
+
+impl<'tcx> FnCtxt<'_, 'tcx> {
+    fn compute_concrete_opaque_types(
+        &mut self,
+        opaque_types: &[(OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>)],
+    ) {
+        let tcx = self.tcx;
+        let TypingMode::Analysis { defining_opaque_types_and_generators } = self.typing_mode()
+        else {
+            unreachable!();
+        };
+
+        for def_id in defining_opaque_types_and_generators {
+            match tcx.def_kind(def_id) {
+                DefKind::OpaqueTy => {}
+                DefKind::Closure => continue,
+                _ => unreachable!("not opaque or generator: {def_id:?}"),
+            }
+
+            let mut usage_kind = UsageKind::None;
+            for &(opaque_type_key, hidden_type) in opaque_types {
+                if opaque_type_key.def_id != def_id {
+                    continue;
+                }
+
+                usage_kind.merge(self.consider_opaque_type_use(opaque_type_key, hidden_type));
+                if let UsageKind::HasDefiningUse = usage_kind {
+                    break;
+                }
+            }
+
+            let guar = match usage_kind {
+                UsageKind::None => {
+                    if let Some(guar) = self.tainted_by_errors() {
+                        guar
+                    } else {
+                        report_item_does_not_constrain_error(self.tcx, self.body_id, def_id, None)
+                    }
+                }
+                UsageKind::NonDefiningUse(opaque_type_key, hidden_type) => {
+                    report_item_does_not_constrain_error(
+                        self.tcx,
+                        self.body_id,
+                        def_id,
+                        Some((opaque_type_key, hidden_type.span)),
+                    )
+                }
+                UsageKind::UnconstrainedHiddenType(hidden_type) => {
+                    let infer_var = hidden_type
+                        .ty
+                        .walk()
+                        .filter_map(ty::GenericArg::as_term)
+                        .find(|term| term.is_infer())
+                        .unwrap_or_else(|| hidden_type.ty.into());
+                    self.err_ctxt()
+                        .emit_inference_failure_err(
+                            self.body_id,
+                            hidden_type.span,
+                            infer_var,
+                            TypeAnnotationNeeded::E0282,
+                            false,
+                        )
+                        .emit()
+                }
+                UsageKind::HasDefiningUse => continue,
+            };
+
+            self.typeck_results
+                .borrow_mut()
+                .concrete_opaque_types
+                .insert(def_id, OpaqueHiddenType::new_error(tcx, guar));
+            self.set_tainted_by_errors(guar);
+        }
+    }
+
+    fn consider_opaque_type_use(
+        &mut self,
+        opaque_type_key: OpaqueTypeKey<'tcx>,
+        hidden_type: OpaqueHiddenType<'tcx>,
+    ) -> UsageKind<'tcx> {
+        if let Err(err) = opaque_type_has_defining_use_args(
+            &self,
+            opaque_type_key,
+            hidden_type.span,
+            DefiningScopeKind::HirTypeck,
+        ) {
+            match err {
+                NonDefiningUseReason::Tainted(guar) => {
+                    self.typeck_results.borrow_mut().concrete_opaque_types.insert(
+                        opaque_type_key.def_id,
+                        OpaqueHiddenType::new_error(self.tcx, guar),
+                    );
+                    return UsageKind::HasDefiningUse;
+                }
+                _ => return UsageKind::NonDefiningUse(opaque_type_key, hidden_type),
+            };
+        }
+
+        // We ignore uses of the opaque if they have any inference variables
+        // as this can frequently happen with recursive calls.
+        //
+        // See `tests/ui/traits/next-solver/opaques/universal-args-non-defining.rs`.
+        if hidden_type.ty.has_non_region_infer() {
+            return UsageKind::UnconstrainedHiddenType(hidden_type);
+        }
+
+        let cause = ObligationCause::misc(hidden_type.span, self.body_id);
+        let at = self.at(&cause, self.param_env);
+        let hidden_type = match solve::deeply_normalize(at, hidden_type) {
+            Ok(hidden_type) => hidden_type,
+            Err(errors) => {
+                let guar = self.err_ctxt().report_fulfillment_errors(errors);
+                OpaqueHiddenType::new_error(self.tcx, guar)
+            }
+        };
+        let hidden_type = hidden_type.remap_generic_params_to_declaration_params(
+            opaque_type_key,
+            self.tcx,
+            DefiningScopeKind::HirTypeck,
+        );
+
+        let prev = self
+            .typeck_results
+            .borrow_mut()
+            .concrete_opaque_types
+            .insert(opaque_type_key.def_id, hidden_type);
+        assert!(prev.is_none());
+        UsageKind::HasDefiningUse
+    }
+
+    fn apply_computed_concrete_opaque_types(
+        &mut self,
+        opaque_types: &[(OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>)],
+    ) {
+        let tcx = self.tcx;
+        for &(key, hidden_type) in opaque_types {
+            let expected =
+                *self.typeck_results.borrow_mut().concrete_opaque_types.get(&key.def_id).unwrap();
+
+            let expected = EarlyBinder::bind(expected.ty).instantiate(tcx, key.args);
+            self.demand_eqtype(hidden_type.span, expected, hidden_type.ty);
+        }
+    }
+
     /// We may in theory add further uses of an opaque after cloning the opaque
     /// types storage during writeback when computing the defining uses.
     ///
diff --git a/compiler/rustc_hir_typeck/src/upvar.rs b/compiler/rustc_hir_typeck/src/upvar.rs
index 50fa3f2cc9d..06acff06a51 100644
--- a/compiler/rustc_hir_typeck/src/upvar.rs
+++ b/compiler/rustc_hir_typeck/src/upvar.rs
@@ -1747,7 +1747,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     }
 
     fn should_log_capture_analysis(&self, closure_def_id: LocalDefId) -> bool {
-        self.tcx.has_attr(closure_def_id, sym::rustc_capture_analysis)
+        self.has_rustc_attrs && self.tcx.has_attr(closure_def_id, sym::rustc_capture_analysis)
     }
 
     fn log_capture_analysis_first_pass(
diff --git a/compiler/rustc_hir_typeck/src/writeback.rs b/compiler/rustc_hir_typeck/src/writeback.rs
index 093de950d63..d75bc9edab2 100644
--- a/compiler/rustc_hir_typeck/src/writeback.rs
+++ b/compiler/rustc_hir_typeck/src/writeback.rs
@@ -27,7 +27,7 @@ use rustc_middle::ty::{
 };
 use rustc_span::{Span, sym};
 use rustc_trait_selection::error_reporting::infer::need_type_info::TypeAnnotationNeeded;
-use rustc_trait_selection::opaque_types::check_opaque_type_parameter_valid;
+use rustc_trait_selection::opaque_types::opaque_type_has_defining_use_args;
 use rustc_trait_selection::solve;
 use tracing::{debug, instrument};
 
@@ -45,7 +45,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         // This attribute causes us to dump some writeback information
         // in the form of errors, which is used for unit tests.
-        let rustc_dump_user_args = self.tcx.has_attr(item_def_id, sym::rustc_dump_user_args);
+        let rustc_dump_user_args =
+            self.has_rustc_attrs && self.tcx.has_attr(item_def_id, sym::rustc_dump_user_args);
 
         let mut wbcx = WritebackCx::new(self, body, rustc_dump_user_args);
         for param in body.params {
@@ -74,7 +75,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         wbcx.visit_user_provided_tys();
         wbcx.visit_user_provided_sigs();
         wbcx.visit_coroutine_interior();
+        wbcx.visit_transmutes();
         wbcx.visit_offset_of_container_types();
+        wbcx.visit_potentially_region_dependent_goals();
 
         wbcx.typeck_results.rvalue_scopes =
             mem::take(&mut self.typeck_results.borrow_mut().rvalue_scopes);
@@ -532,8 +535,36 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
         }
     }
 
+    fn visit_transmutes(&mut self) {
+        let tcx = self.tcx();
+        let fcx_typeck_results = self.fcx.typeck_results.borrow();
+        assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
+        for &(from, to, hir_id) in self.fcx.deferred_transmute_checks.borrow().iter() {
+            let span = tcx.hir_span(hir_id);
+            let from = self.resolve(from, &span);
+            let to = self.resolve(to, &span);
+            self.typeck_results.transmutes_to_check.push((from, to, hir_id));
+        }
+    }
+
+    fn visit_opaque_types_next(&mut self) {
+        let mut fcx_typeck_results = self.fcx.typeck_results.borrow_mut();
+        assert_eq!(fcx_typeck_results.hir_owner, self.typeck_results.hir_owner);
+        for hidden_ty in fcx_typeck_results.concrete_opaque_types.values() {
+            assert!(!hidden_ty.has_infer());
+        }
+
+        assert_eq!(self.typeck_results.concrete_opaque_types.len(), 0);
+        self.typeck_results.concrete_opaque_types =
+            mem::take(&mut fcx_typeck_results.concrete_opaque_types);
+    }
+
     #[instrument(skip(self), level = "debug")]
     fn visit_opaque_types(&mut self) {
+        if self.fcx.next_trait_solver() {
+            return self.visit_opaque_types_next();
+        }
+
         let tcx = self.tcx();
         // We clone the opaques instead of stealing them here as they are still used for
         // normalization in the next generation trait solver.
@@ -544,17 +575,14 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
         for (opaque_type_key, hidden_type) in opaque_types {
             let hidden_type = self.resolve(hidden_type, &hidden_type.span);
             let opaque_type_key = self.resolve(opaque_type_key, &hidden_type.span);
-
-            if !self.fcx.next_trait_solver() {
-                if let ty::Alias(ty::Opaque, alias_ty) = hidden_type.ty.kind()
-                    && alias_ty.def_id == opaque_type_key.def_id.to_def_id()
-                    && alias_ty.args == opaque_type_key.args
-                {
-                    continue;
-                }
+            if let ty::Alias(ty::Opaque, alias_ty) = hidden_type.ty.kind()
+                && alias_ty.def_id == opaque_type_key.def_id.to_def_id()
+                && alias_ty.args == opaque_type_key.args
+            {
+                continue;
             }
 
-            if let Err(err) = check_opaque_type_parameter_valid(
+            if let Err(err) = opaque_type_has_defining_use_args(
                 &self.fcx,
                 opaque_type_key,
                 hidden_type.span,
@@ -762,6 +790,32 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
         }
     }
 
+    fn visit_potentially_region_dependent_goals(&mut self) {
+        let obligations = self.fcx.take_hir_typeck_potentially_region_dependent_goals();
+        if let None = self.fcx.tainted_by_errors() {
+            for obligation in obligations {
+                let (predicate, mut cause) =
+                    self.fcx.resolve_vars_if_possible((obligation.predicate, obligation.cause));
+                if predicate.has_non_region_infer() {
+                    self.fcx.dcx().span_delayed_bug(
+                        cause.span,
+                        format!("unexpected inference variable after writeback: {predicate:?}"),
+                    );
+                } else {
+                    let predicate = self.tcx().erase_regions(predicate);
+                    if cause.has_infer() || cause.has_placeholders() {
+                        // We can't use the the obligation cause as it references
+                        // information local to this query.
+                        cause = self.fcx.misc(cause.span);
+                    }
+                    self.typeck_results
+                        .potentially_region_dependent_goals
+                        .insert((predicate, cause));
+                }
+            }
+        }
+    }
+
     fn resolve<T>(&mut self, value: T, span: &dyn Locatable) -> T
     where
         T: TypeFoldable<TyCtxt<'tcx>>,
@@ -883,6 +937,7 @@ impl<'cx, 'tcx> Resolver<'cx, 'tcx> {
         }
     }
 
+    #[instrument(level = "debug", skip(self, outer_exclusive_binder, new_err))]
     fn handle_term<T>(
         &mut self,
         value: T,
diff --git a/compiler/rustc_incremental/Cargo.toml b/compiler/rustc_incremental/Cargo.toml
index db0a5841887..8d7f2eb8414 100644
--- a/compiler/rustc_incremental/Cargo.toml
+++ b/compiler/rustc_incremental/Cargo.toml
@@ -19,6 +19,6 @@ rustc_middle = { path = "../rustc_middle" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
-thin-vec = "0.2.12"
-tracing = "0.1"
+thin-vec.workspace = true
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_index/src/bit_set.rs b/compiler/rustc_index/src/bit_set.rs
index 645d95b1dba..684bd34f909 100644
--- a/compiler/rustc_index/src/bit_set.rs
+++ b/compiler/rustc_index/src/bit_set.rs
@@ -491,19 +491,15 @@ pub struct ChunkedBitSet<T> {
     marker: PhantomData<T>,
 }
 
-// Note: the chunk domain size is duplicated in each variant. This is a bit
-// inconvenient, but it allows the type size to be smaller than if we had an
-// outer struct containing a chunk domain size plus the `Chunk`, because the
-// compiler can place the chunk domain size after the tag.
+// NOTE: The chunk size is computed on-the-fly on each manipulation of a chunk.
+// This avoids storing it, as it's almost always CHUNK_BITS except for the last one.
 #[derive(Clone, Debug, PartialEq, Eq)]
 enum Chunk {
     /// A chunk that is all zeros; we don't represent the zeros explicitly.
-    /// The `ChunkSize` is always non-zero.
-    Zeros(ChunkSize),
+    Zeros,
 
     /// A chunk that is all ones; we don't represent the ones explicitly.
-    /// `ChunkSize` is always non-zero.
-    Ones(ChunkSize),
+    Ones,
 
     /// A chunk that has a mix of zeros and ones, which are represented
     /// explicitly and densely. It never has all zeros or all ones.
@@ -514,16 +510,14 @@ enum Chunk {
     /// to store the length, which would make this type larger. These excess
     /// words are always zero, as are any excess bits in the final in-use word.
     ///
-    /// The first `ChunkSize` field is always non-zero.
-    ///
-    /// The second `ChunkSize` field is the count of 1s set in the chunk, and
+    /// The `ChunkSize` field is the count of 1s set in the chunk, and
     /// must satisfy `0 < count < chunk_domain_size`.
     ///
     /// The words are within an `Rc` because it's surprisingly common to
     /// duplicate an entire chunk, e.g. in `ChunkedBitSet::clone_from()`, or
     /// when a `Mixed` chunk is union'd into a `Zeros` chunk. When we do need
     /// to modify a chunk we use `Rc::make_mut`.
-    Mixed(ChunkSize, ChunkSize, Rc<[Word; CHUNK_WORDS]>),
+    Mixed(ChunkSize, Rc<[Word; CHUNK_WORDS]>),
 }
 
 // This type is used a lot. Make sure it doesn't unintentionally get bigger.
@@ -535,6 +529,22 @@ impl<T> ChunkedBitSet<T> {
         self.domain_size
     }
 
+    #[inline]
+    fn last_chunk_size(&self) -> ChunkSize {
+        let n = self.domain_size % CHUNK_BITS;
+        if n == 0 { CHUNK_BITS as ChunkSize } else { n as ChunkSize }
+    }
+
+    /// All the chunks have a chunk_domain_size of `CHUNK_BITS` except the final one.
+    #[inline]
+    fn chunk_domain_size(&self, chunk: usize) -> ChunkSize {
+        if chunk == self.chunks.len() - 1 {
+            self.last_chunk_size()
+        } else {
+            CHUNK_BITS as ChunkSize
+        }
+    }
+
     #[cfg(test)]
     fn assert_valid(&self) {
         if self.domain_size == 0 {
@@ -544,8 +554,9 @@ impl<T> ChunkedBitSet<T> {
 
         assert!((self.chunks.len() - 1) * CHUNK_BITS <= self.domain_size);
         assert!(self.chunks.len() * CHUNK_BITS >= self.domain_size);
-        for chunk in self.chunks.iter() {
-            chunk.assert_valid();
+        for (chunk_index, chunk) in self.chunks.iter().enumerate() {
+            let chunk_domain_size = self.chunk_domain_size(chunk_index);
+            chunk.assert_valid(chunk_domain_size);
         }
     }
 }
@@ -556,16 +567,7 @@ impl<T: Idx> ChunkedBitSet<T> {
         let chunks = if domain_size == 0 {
             Box::new([])
         } else {
-            // All the chunks have a chunk_domain_size of `CHUNK_BITS` except
-            // the final one.
-            let final_chunk_domain_size = {
-                let n = domain_size % CHUNK_BITS;
-                if n == 0 { CHUNK_BITS } else { n }
-            };
-            let mut chunks =
-                vec![Chunk::new(CHUNK_BITS, is_empty); num_chunks(domain_size)].into_boxed_slice();
-            *chunks.last_mut().unwrap() = Chunk::new(final_chunk_domain_size, is_empty);
-            chunks
+            vec![if is_empty { Zeros } else { Ones }; num_chunks(domain_size)].into_boxed_slice()
         };
         ChunkedBitSet { domain_size, chunks, marker: PhantomData }
     }
@@ -594,11 +596,15 @@ impl<T: Idx> ChunkedBitSet<T> {
 
     /// Count the number of bits in the set.
     pub fn count(&self) -> usize {
-        self.chunks.iter().map(|chunk| chunk.count()).sum()
+        self.chunks
+            .iter()
+            .enumerate()
+            .map(|(index, chunk)| chunk.count(self.chunk_domain_size(index)))
+            .sum()
     }
 
     pub fn is_empty(&self) -> bool {
-        self.chunks.iter().all(|chunk| matches!(chunk, Zeros(..)))
+        self.chunks.iter().all(|chunk| matches!(chunk, Zeros))
     }
 
     /// Returns `true` if `self` contains `elem`.
@@ -607,9 +613,9 @@ impl<T: Idx> ChunkedBitSet<T> {
         assert!(elem.index() < self.domain_size);
         let chunk = &self.chunks[chunk_index(elem)];
         match &chunk {
-            Zeros(_) => false,
-            Ones(_) => true,
-            Mixed(_, _, words) => {
+            Zeros => false,
+            Ones => true,
+            Mixed(_, words) => {
                 let (word_index, mask) = chunk_word_index_and_mask(elem);
                 (words[word_index] & mask) != 0
             }
@@ -625,9 +631,10 @@ impl<T: Idx> ChunkedBitSet<T> {
     pub fn insert(&mut self, elem: T) -> bool {
         assert!(elem.index() < self.domain_size);
         let chunk_index = chunk_index(elem);
+        let chunk_domain_size = self.chunk_domain_size(chunk_index);
         let chunk = &mut self.chunks[chunk_index];
         match *chunk {
-            Zeros(chunk_domain_size) => {
+            Zeros => {
                 if chunk_domain_size > 1 {
                     #[cfg(feature = "nightly")]
                     let mut words = {
@@ -649,14 +656,14 @@ impl<T: Idx> ChunkedBitSet<T> {
 
                     let (word_index, mask) = chunk_word_index_and_mask(elem);
                     words_ref[word_index] |= mask;
-                    *chunk = Mixed(chunk_domain_size, 1, words);
+                    *chunk = Mixed(1, words);
                 } else {
-                    *chunk = Ones(chunk_domain_size);
+                    *chunk = Ones;
                 }
                 true
             }
-            Ones(_) => false,
-            Mixed(chunk_domain_size, ref mut count, ref mut words) => {
+            Ones => false,
+            Mixed(ref mut count, ref mut words) => {
                 // We skip all the work if the bit is already set.
                 let (word_index, mask) = chunk_word_index_and_mask(elem);
                 if (words[word_index] & mask) == 0 {
@@ -665,7 +672,7 @@ impl<T: Idx> ChunkedBitSet<T> {
                         let words = Rc::make_mut(words);
                         words[word_index] |= mask;
                     } else {
-                        *chunk = Ones(chunk_domain_size);
+                        *chunk = Ones;
                     }
                     true
                 } else {
@@ -678,11 +685,7 @@ impl<T: Idx> ChunkedBitSet<T> {
     /// Sets all bits to true.
     pub fn insert_all(&mut self) {
         for chunk in self.chunks.iter_mut() {
-            *chunk = match *chunk {
-                Zeros(chunk_domain_size)
-                | Ones(chunk_domain_size)
-                | Mixed(chunk_domain_size, ..) => Ones(chunk_domain_size),
-            }
+            *chunk = Ones;
         }
     }
 
@@ -690,10 +693,11 @@ impl<T: Idx> ChunkedBitSet<T> {
     pub fn remove(&mut self, elem: T) -> bool {
         assert!(elem.index() < self.domain_size);
         let chunk_index = chunk_index(elem);
+        let chunk_domain_size = self.chunk_domain_size(chunk_index);
         let chunk = &mut self.chunks[chunk_index];
         match *chunk {
-            Zeros(_) => false,
-            Ones(chunk_domain_size) => {
+            Zeros => false,
+            Ones => {
                 if chunk_domain_size > 1 {
                     #[cfg(feature = "nightly")]
                     let mut words = {
@@ -722,13 +726,13 @@ impl<T: Idx> ChunkedBitSet<T> {
                     );
                     let (word_index, mask) = chunk_word_index_and_mask(elem);
                     words_ref[word_index] &= !mask;
-                    *chunk = Mixed(chunk_domain_size, chunk_domain_size - 1, words);
+                    *chunk = Mixed(chunk_domain_size - 1, words);
                 } else {
-                    *chunk = Zeros(chunk_domain_size);
+                    *chunk = Zeros;
                 }
                 true
             }
-            Mixed(chunk_domain_size, ref mut count, ref mut words) => {
+            Mixed(ref mut count, ref mut words) => {
                 // We skip all the work if the bit is already clear.
                 let (word_index, mask) = chunk_word_index_and_mask(elem);
                 if (words[word_index] & mask) != 0 {
@@ -737,7 +741,7 @@ impl<T: Idx> ChunkedBitSet<T> {
                         let words = Rc::make_mut(words);
                         words[word_index] &= !mask;
                     } else {
-                        *chunk = Zeros(chunk_domain_size);
+                        *chunk = Zeros
                     }
                     true
                 } else {
@@ -748,11 +752,12 @@ impl<T: Idx> ChunkedBitSet<T> {
     }
 
     fn chunk_iter(&self, chunk_index: usize) -> ChunkIter<'_> {
+        let chunk_domain_size = self.chunk_domain_size(chunk_index);
         match self.chunks.get(chunk_index) {
-            Some(Zeros(_chunk_domain_size)) => ChunkIter::Zeros,
-            Some(Ones(chunk_domain_size)) => ChunkIter::Ones(0..*chunk_domain_size as usize),
-            Some(Mixed(chunk_domain_size, _, words)) => {
-                let num_words = num_words(*chunk_domain_size as usize);
+            Some(Zeros) => ChunkIter::Zeros,
+            Some(Ones) => ChunkIter::Ones(0..chunk_domain_size as usize),
+            Some(Mixed(_, words)) => {
+                let num_words = num_words(chunk_domain_size as usize);
                 ChunkIter::Mixed(BitIter::new(&words[0..num_words]))
             }
             None => ChunkIter::Finished,
@@ -765,23 +770,33 @@ impl<T: Idx> ChunkedBitSet<T> {
 impl<T: Idx> BitRelations<ChunkedBitSet<T>> for ChunkedBitSet<T> {
     fn union(&mut self, other: &ChunkedBitSet<T>) -> bool {
         assert_eq!(self.domain_size, other.domain_size);
-        debug_assert_eq!(self.chunks.len(), other.chunks.len());
+
+        let num_chunks = self.chunks.len();
+        debug_assert_eq!(num_chunks, other.chunks.len());
+
+        let last_chunk_size = self.last_chunk_size();
+        debug_assert_eq!(last_chunk_size, other.last_chunk_size());
 
         let mut changed = false;
-        for (mut self_chunk, other_chunk) in self.chunks.iter_mut().zip(other.chunks.iter()) {
+        for (chunk_index, (mut self_chunk, other_chunk)) in
+            self.chunks.iter_mut().zip(other.chunks.iter()).enumerate()
+        {
+            let chunk_domain_size = if chunk_index + 1 == num_chunks {
+                last_chunk_size
+            } else {
+                CHUNK_BITS as ChunkSize
+            };
+
             match (&mut self_chunk, &other_chunk) {
-                (_, Zeros(_)) | (Ones(_), _) => {}
-                (Zeros(self_chunk_domain_size), Ones(other_chunk_domain_size))
-                | (Mixed(self_chunk_domain_size, ..), Ones(other_chunk_domain_size))
-                | (Zeros(self_chunk_domain_size), Mixed(other_chunk_domain_size, ..)) => {
+                (_, Zeros) | (Ones, _) => {}
+                (Zeros, Ones) | (Mixed(..), Ones) | (Zeros, Mixed(..)) => {
                     // `other_chunk` fully overwrites `self_chunk`
-                    debug_assert_eq!(self_chunk_domain_size, other_chunk_domain_size);
                     *self_chunk = other_chunk.clone();
                     changed = true;
                 }
                 (
-                    Mixed(self_chunk_domain_size, self_chunk_count, self_chunk_words),
-                    Mixed(_other_chunk_domain_size, _other_chunk_count, other_chunk_words),
+                    Mixed(self_chunk_count, self_chunk_words),
+                    Mixed(_other_chunk_count, other_chunk_words),
                 ) => {
                     // First check if the operation would change
                     // `self_chunk.words`. If not, we can avoid allocating some
@@ -789,7 +804,7 @@ impl<T: Idx> BitRelations<ChunkedBitSet<T>> for ChunkedBitSet<T> {
                     // performance win. Also, we only need to operate on the
                     // in-use words, hence the slicing.
                     let op = |a, b| a | b;
-                    let num_words = num_words(*self_chunk_domain_size as usize);
+                    let num_words = num_words(chunk_domain_size as usize);
                     if bitwise_changes(
                         &self_chunk_words[0..num_words],
                         &other_chunk_words[0..num_words],
@@ -806,8 +821,8 @@ impl<T: Idx> BitRelations<ChunkedBitSet<T>> for ChunkedBitSet<T> {
                             .iter()
                             .map(|w| w.count_ones() as ChunkSize)
                             .sum();
-                        if *self_chunk_count == *self_chunk_domain_size {
-                            *self_chunk = Ones(*self_chunk_domain_size);
+                        if *self_chunk_count == chunk_domain_size {
+                            *self_chunk = Ones;
                         }
                         changed = true;
                     }
@@ -819,36 +834,41 @@ impl<T: Idx> BitRelations<ChunkedBitSet<T>> for ChunkedBitSet<T> {
 
     fn subtract(&mut self, other: &ChunkedBitSet<T>) -> bool {
         assert_eq!(self.domain_size, other.domain_size);
-        debug_assert_eq!(self.chunks.len(), other.chunks.len());
+
+        let num_chunks = self.chunks.len();
+        debug_assert_eq!(num_chunks, other.chunks.len());
+
+        let last_chunk_size = self.last_chunk_size();
+        debug_assert_eq!(last_chunk_size, other.last_chunk_size());
 
         let mut changed = false;
-        for (mut self_chunk, other_chunk) in self.chunks.iter_mut().zip(other.chunks.iter()) {
+        for (chunk_index, (mut self_chunk, other_chunk)) in
+            self.chunks.iter_mut().zip(other.chunks.iter()).enumerate()
+        {
+            let chunk_domain_size = if chunk_index + 1 == num_chunks {
+                last_chunk_size
+            } else {
+                CHUNK_BITS as ChunkSize
+            };
+
             match (&mut self_chunk, &other_chunk) {
-                (Zeros(..), _) | (_, Zeros(..)) => {}
-                (
-                    Ones(self_chunk_domain_size) | Mixed(self_chunk_domain_size, _, _),
-                    Ones(other_chunk_domain_size),
-                ) => {
-                    debug_assert_eq!(self_chunk_domain_size, other_chunk_domain_size);
+                (Zeros, _) | (_, Zeros) => {}
+                (Ones | Mixed(_, _), Ones) => {
                     changed = true;
-                    *self_chunk = Zeros(*self_chunk_domain_size);
+                    *self_chunk = Zeros;
                 }
-                (
-                    Ones(self_chunk_domain_size),
-                    Mixed(other_chunk_domain_size, other_chunk_count, other_chunk_words),
-                ) => {
-                    debug_assert_eq!(self_chunk_domain_size, other_chunk_domain_size);
+                (Ones, Mixed(other_chunk_count, other_chunk_words)) => {
                     changed = true;
-                    let num_words = num_words(*self_chunk_domain_size as usize);
+                    let num_words = num_words(chunk_domain_size as usize);
                     debug_assert!(num_words > 0 && num_words <= CHUNK_WORDS);
                     let mut tail_mask =
-                        1 << (*other_chunk_domain_size - ((num_words - 1) * WORD_BITS) as u16) - 1;
+                        1 << (chunk_domain_size - ((num_words - 1) * WORD_BITS) as u16) - 1;
                     let mut self_chunk_words = **other_chunk_words;
                     for word in self_chunk_words[0..num_words].iter_mut().rev() {
                         *word = !*word & tail_mask;
                         tail_mask = u64::MAX;
                     }
-                    let self_chunk_count = *self_chunk_domain_size - *other_chunk_count;
+                    let self_chunk_count = chunk_domain_size - *other_chunk_count;
                     debug_assert_eq!(
                         self_chunk_count,
                         self_chunk_words[0..num_words]
@@ -856,16 +876,15 @@ impl<T: Idx> BitRelations<ChunkedBitSet<T>> for ChunkedBitSet<T> {
                             .map(|w| w.count_ones() as ChunkSize)
                             .sum()
                     );
-                    *self_chunk =
-                        Mixed(*self_chunk_domain_size, self_chunk_count, Rc::new(self_chunk_words));
+                    *self_chunk = Mixed(self_chunk_count, Rc::new(self_chunk_words));
                 }
                 (
-                    Mixed(self_chunk_domain_size, self_chunk_count, self_chunk_words),
-                    Mixed(_other_chunk_domain_size, _other_chunk_count, other_chunk_words),
+                    Mixed(self_chunk_count, self_chunk_words),
+                    Mixed(_other_chunk_count, other_chunk_words),
                 ) => {
                     // See [`<Self as BitRelations<ChunkedBitSet<T>>>::union`] for the explanation
                     let op = |a: u64, b: u64| a & !b;
-                    let num_words = num_words(*self_chunk_domain_size as usize);
+                    let num_words = num_words(chunk_domain_size as usize);
                     if bitwise_changes(
                         &self_chunk_words[0..num_words],
                         &other_chunk_words[0..num_words],
@@ -883,7 +902,7 @@ impl<T: Idx> BitRelations<ChunkedBitSet<T>> for ChunkedBitSet<T> {
                             .map(|w| w.count_ones() as ChunkSize)
                             .sum();
                         if *self_chunk_count == 0 {
-                            *self_chunk = Zeros(*self_chunk_domain_size);
+                            *self_chunk = Zeros;
                         }
                         changed = true;
                     }
@@ -895,28 +914,36 @@ impl<T: Idx> BitRelations<ChunkedBitSet<T>> for ChunkedBitSet<T> {
 
     fn intersect(&mut self, other: &ChunkedBitSet<T>) -> bool {
         assert_eq!(self.domain_size, other.domain_size);
-        debug_assert_eq!(self.chunks.len(), other.chunks.len());
+
+        let num_chunks = self.chunks.len();
+        debug_assert_eq!(num_chunks, other.chunks.len());
+
+        let last_chunk_size = self.last_chunk_size();
+        debug_assert_eq!(last_chunk_size, other.last_chunk_size());
 
         let mut changed = false;
-        for (mut self_chunk, other_chunk) in self.chunks.iter_mut().zip(other.chunks.iter()) {
+        for (chunk_index, (mut self_chunk, other_chunk)) in
+            self.chunks.iter_mut().zip(other.chunks.iter()).enumerate()
+        {
+            let chunk_domain_size = if chunk_index + 1 == num_chunks {
+                last_chunk_size
+            } else {
+                CHUNK_BITS as ChunkSize
+            };
+
             match (&mut self_chunk, &other_chunk) {
-                (Zeros(..), _) | (_, Ones(..)) => {}
-                (
-                    Ones(self_chunk_domain_size),
-                    Zeros(other_chunk_domain_size) | Mixed(other_chunk_domain_size, ..),
-                )
-                | (Mixed(self_chunk_domain_size, ..), Zeros(other_chunk_domain_size)) => {
-                    debug_assert_eq!(self_chunk_domain_size, other_chunk_domain_size);
+                (Zeros, _) | (_, Ones) => {}
+                (Ones, Zeros | Mixed(..)) | (Mixed(..), Zeros) => {
                     changed = true;
                     *self_chunk = other_chunk.clone();
                 }
                 (
-                    Mixed(self_chunk_domain_size, self_chunk_count, self_chunk_words),
-                    Mixed(_other_chunk_domain_size, _other_chunk_count, other_chunk_words),
+                    Mixed(self_chunk_count, self_chunk_words),
+                    Mixed(_other_chunk_count, other_chunk_words),
                 ) => {
                     // See [`<Self as BitRelations<ChunkedBitSet<T>>>::union`] for the explanation
                     let op = |a, b| a & b;
-                    let num_words = num_words(*self_chunk_domain_size as usize);
+                    let num_words = num_words(chunk_domain_size as usize);
                     if bitwise_changes(
                         &self_chunk_words[0..num_words],
                         &other_chunk_words[0..num_words],
@@ -934,7 +961,7 @@ impl<T: Idx> BitRelations<ChunkedBitSet<T>> for ChunkedBitSet<T> {
                             .map(|w| w.count_ones() as ChunkSize)
                             .sum();
                         if *self_chunk_count == 0 {
-                            *self_chunk = Zeros(*self_chunk_domain_size);
+                            *self_chunk = Zeros;
                         }
                         changed = true;
                     }
@@ -964,7 +991,7 @@ impl<T: Idx> BitRelations<ChunkedBitSet<T>> for DenseBitSet<T> {
                 words = &mut words[..CHUNK_WORDS];
             }
             match chunk {
-                Zeros(..) => {
+                Zeros => {
                     for word in words {
                         if *word != 0 {
                             changed = true;
@@ -972,8 +999,8 @@ impl<T: Idx> BitRelations<ChunkedBitSet<T>> for DenseBitSet<T> {
                         }
                     }
                 }
-                Ones(..) => (),
-                Mixed(_, _, data) => {
+                Ones => (),
+                Mixed(_, data) => {
                     for (i, word) in words.iter_mut().enumerate() {
                         let new_val = *word & data[i];
                         if new_val != *word {
@@ -1053,13 +1080,11 @@ impl<'a, T: Idx> Iterator for ChunkedBitIter<'a, T> {
 
 impl Chunk {
     #[cfg(test)]
-    fn assert_valid(&self) {
+    fn assert_valid(&self, chunk_domain_size: ChunkSize) {
+        assert!(chunk_domain_size as usize <= CHUNK_BITS);
         match *self {
-            Zeros(chunk_domain_size) | Ones(chunk_domain_size) => {
-                assert!(chunk_domain_size as usize <= CHUNK_BITS);
-            }
-            Mixed(chunk_domain_size, count, ref words) => {
-                assert!(chunk_domain_size as usize <= CHUNK_BITS);
+            Zeros | Ones => {}
+            Mixed(count, ref words) => {
                 assert!(0 < count && count < chunk_domain_size);
 
                 // Check the number of set bits matches `count`.
@@ -1083,18 +1108,12 @@ impl Chunk {
         }
     }
 
-    fn new(chunk_domain_size: usize, is_empty: bool) -> Self {
-        debug_assert!(0 < chunk_domain_size && chunk_domain_size <= CHUNK_BITS);
-        let chunk_domain_size = chunk_domain_size as ChunkSize;
-        if is_empty { Zeros(chunk_domain_size) } else { Ones(chunk_domain_size) }
-    }
-
     /// Count the number of 1s in the chunk.
-    fn count(&self) -> usize {
+    fn count(&self, chunk_domain_size: ChunkSize) -> usize {
         match *self {
-            Zeros(_) => 0,
-            Ones(chunk_domain_size) => chunk_domain_size as usize,
-            Mixed(_, count, _) => count as usize,
+            Zeros => 0,
+            Ones => chunk_domain_size as usize,
+            Mixed(count, _) => count as usize,
         }
     }
 }
diff --git a/compiler/rustc_index/src/bit_set/tests.rs b/compiler/rustc_index/src/bit_set/tests.rs
index 9ce4cf4293f..deddc872614 100644
--- a/compiler/rustc_index/src/bit_set/tests.rs
+++ b/compiler/rustc_index/src/bit_set/tests.rs
@@ -120,8 +120,9 @@ fn chunked_bitset() {
     let mut b1 = ChunkedBitSet::<usize>::new_empty(1);
     assert_eq!(
         b1,
-        ChunkedBitSet { domain_size: 1, chunks: Box::new([Zeros(1)]), marker: PhantomData }
+        ChunkedBitSet { domain_size: 1, chunks: Box::new([Zeros]), marker: PhantomData }
     );
+    assert_eq!(b1.chunk_domain_size(0), 1);
 
     b1.assert_valid();
     assert!(!b1.contains(0));
@@ -129,12 +130,12 @@ fn chunked_bitset() {
     assert!(b1.insert(0));
     assert!(b1.contains(0));
     assert_eq!(b1.count(), 1);
-    assert_eq!(b1.chunks(), [Ones(1)]);
+    assert_eq!(b1.chunks(), [Ones]);
     assert!(!b1.insert(0));
     assert!(b1.remove(0));
     assert!(!b1.contains(0));
     assert_eq!(b1.count(), 0);
-    assert_eq!(b1.chunks(), [Zeros(1)]);
+    assert_eq!(b1.chunks(), [Zeros]);
     b1.assert_valid();
 
     //-----------------------------------------------------------------------
@@ -142,8 +143,9 @@ fn chunked_bitset() {
     let mut b100 = ChunkedBitSet::<usize>::new_filled(100);
     assert_eq!(
         b100,
-        ChunkedBitSet { domain_size: 100, chunks: Box::new([Ones(100)]), marker: PhantomData }
+        ChunkedBitSet { domain_size: 100, chunks: Box::new([Ones]), marker: PhantomData }
     );
+    assert_eq!(b100.chunk_domain_size(0), 100);
 
     b100.assert_valid();
     for i in 0..100 {
@@ -152,7 +154,7 @@ fn chunked_bitset() {
     assert_eq!(b100.count(), 100);
     assert!(b100.remove(3));
     assert!(b100.insert(3));
-    assert_eq!(b100.chunks(), vec![Ones(100)]);
+    assert_eq!(b100.chunks(), vec![Ones]);
     assert!(
         b100.remove(20) && b100.remove(30) && b100.remove(40) && b100.remove(99) && b100.insert(30)
     );
@@ -161,7 +163,6 @@ fn chunked_bitset() {
     assert_eq!(
         b100.chunks(),
         vec![Mixed(
-            100,
             97,
             #[rustfmt::skip]
             Rc::new([
@@ -180,7 +181,7 @@ fn chunked_bitset() {
         }
     }
     assert_eq!(num_removed, 97);
-    assert_eq!(b100.chunks(), vec![Zeros(100)]);
+    assert_eq!(b100.chunks(), vec![Zeros]);
     b100.assert_valid();
 
     //-----------------------------------------------------------------------
@@ -188,23 +189,21 @@ fn chunked_bitset() {
     let mut b2548 = ChunkedBitSet::<usize>::new_empty(2548);
     assert_eq!(
         b2548,
-        ChunkedBitSet {
-            domain_size: 2548,
-            chunks: Box::new([Zeros(2048), Zeros(500)]),
-            marker: PhantomData,
-        }
+        ChunkedBitSet { domain_size: 2548, chunks: Box::new([Zeros, Zeros]), marker: PhantomData }
     );
+    assert_eq!(b2548.chunk_domain_size(0), 2048);
+    assert_eq!(b2548.chunk_domain_size(1), 500);
 
     b2548.assert_valid();
     b2548.insert(14);
     b2548.remove(14);
-    assert_eq!(b2548.chunks(), vec![Zeros(2048), Zeros(500)]);
+    assert_eq!(b2548.chunks(), vec![Zeros, Zeros]);
     b2548.insert_all();
     for i in 0..2548 {
         assert!(b2548.contains(i));
     }
     assert_eq!(b2548.count(), 2548);
-    assert_eq!(b2548.chunks(), vec![Ones(2048), Ones(500)]);
+    assert_eq!(b2548.chunks(), vec![Ones, Ones]);
     b2548.assert_valid();
 
     //-----------------------------------------------------------------------
@@ -212,12 +211,10 @@ fn chunked_bitset() {
     let mut b4096 = ChunkedBitSet::<usize>::new_empty(4096);
     assert_eq!(
         b4096,
-        ChunkedBitSet {
-            domain_size: 4096,
-            chunks: Box::new([Zeros(2048), Zeros(2048)]),
-            marker: PhantomData,
-        }
+        ChunkedBitSet { domain_size: 4096, chunks: Box::new([Zeros, Zeros]), marker: PhantomData }
     );
+    assert_eq!(b4096.chunk_domain_size(0), 2048);
+    assert_eq!(b4096.chunk_domain_size(1), 2048);
 
     b4096.assert_valid();
     for i in 0..4096 {
@@ -231,11 +228,11 @@ fn chunked_bitset() {
         b4096.chunks(),
         #[rustfmt::skip]
         vec![
-            Mixed(2048, 1, Rc::new([
+            Mixed(1, Rc::new([
                 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
             ])),
-            Mixed(2048, 1, Rc::new([
+            Mixed(1, Rc::new([
                 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x8000_0000_0000_0000
             ])),
@@ -251,10 +248,15 @@ fn chunked_bitset() {
         b10000,
         ChunkedBitSet {
             domain_size: 10000,
-            chunks: Box::new([Zeros(2048), Zeros(2048), Zeros(2048), Zeros(2048), Zeros(1808),]),
+            chunks: Box::new([Zeros, Zeros, Zeros, Zeros, Zeros,]),
             marker: PhantomData,
         }
     );
+    assert_eq!(b10000.chunk_domain_size(0), 2048);
+    assert_eq!(b10000.chunk_domain_size(1), 2048);
+    assert_eq!(b10000.chunk_domain_size(2), 2048);
+    assert_eq!(b10000.chunk_domain_size(3), 2048);
+    assert_eq!(b10000.chunk_domain_size(4), 1808);
 
     b10000.assert_valid();
     assert!(b10000.insert(3000) && b10000.insert(5000));
@@ -262,17 +264,17 @@ fn chunked_bitset() {
         b10000.chunks(),
         #[rustfmt::skip]
         vec![
-            Zeros(2048),
-            Mixed(2048, 1, Rc::new([
+            Zeros,
+            Mixed(1, Rc::new([
                 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x0100_0000_0000_0000, 0,
                 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
             ])),
-            Mixed(2048, 1, Rc::new([
+            Mixed(1, Rc::new([
                 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x0100, 0,
                 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
             ])),
-            Zeros(2048),
-            Zeros(1808),
+            Zeros,
+            Zeros,
         ],
     );
     let mut b10000b = ChunkedBitSet::<usize>::new_empty(10000);
diff --git a/compiler/rustc_infer/Cargo.toml b/compiler/rustc_infer/Cargo.toml
index 08c03614884..6d97fa6af1f 100644
--- a/compiler/rustc_infer/Cargo.toml
+++ b/compiler/rustc_infer/Cargo.toml
@@ -18,6 +18,6 @@ rustc_middle = { path = "../rustc_middle" }
 rustc_span = { path = "../rustc_span" }
 rustc_type_ir = { path = "../rustc_type_ir" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec = "0.2.12"
-tracing = "0.1"
+thin-vec.workspace = true
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_infer/src/infer/context.rs b/compiler/rustc_infer/src/infer/context.rs
index 21e999b080d..bb9c8850093 100644
--- a/compiler/rustc_infer/src/infer/context.rs
+++ b/compiler/rustc_infer/src/infer/context.rs
@@ -22,10 +22,6 @@ impl<'tcx> rustc_type_ir::InferCtxtLike for InferCtxt<'tcx> {
         self.next_trait_solver
     }
 
-    fn in_hir_typeck(&self) -> bool {
-        self.in_hir_typeck
-    }
-
     fn typing_mode(&self) -> ty::TypingMode<'tcx> {
         self.typing_mode()
     }
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index 82d4856df39..d1507f08c06 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -158,7 +158,8 @@ pub struct InferCtxtInner<'tcx> {
     region_assumptions: Vec<ty::ArgOutlivesPredicate<'tcx>>,
 
     /// `-Znext-solver`: Successfully proven goals during HIR typeck which
-    /// reference inference variables and get reproven after writeback.
+    /// reference inference variables and get reproven in case MIR type check
+    /// fails to prove something.
     ///
     /// See the documentation of `InferCtxt::in_hir_typeck` for more details.
     hir_typeck_potentially_region_dependent_goals: Vec<PredicateObligation<'tcx>>,
@@ -782,22 +783,30 @@ impl<'tcx> InferCtxt<'tcx> {
         self.inner.borrow_mut().type_variables().num_vars()
     }
 
-    pub fn next_ty_var(&self, span: Span) -> Ty<'tcx> {
-        self.next_ty_var_with_origin(TypeVariableOrigin { span, param_def_id: None })
+    pub fn next_ty_vid(&self, span: Span) -> TyVid {
+        self.next_ty_vid_with_origin(TypeVariableOrigin { span, param_def_id: None })
     }
 
-    pub fn next_ty_var_with_origin(&self, origin: TypeVariableOrigin) -> Ty<'tcx> {
-        let vid = self.inner.borrow_mut().type_variables().new_var(self.universe(), origin);
-        Ty::new_var(self.tcx, vid)
+    pub fn next_ty_vid_with_origin(&self, origin: TypeVariableOrigin) -> TyVid {
+        self.inner.borrow_mut().type_variables().new_var(self.universe(), origin)
     }
 
-    pub fn next_ty_var_id_in_universe(&self, span: Span, universe: ty::UniverseIndex) -> TyVid {
+    pub fn next_ty_vid_in_universe(&self, span: Span, universe: ty::UniverseIndex) -> TyVid {
         let origin = TypeVariableOrigin { span, param_def_id: None };
         self.inner.borrow_mut().type_variables().new_var(universe, origin)
     }
 
+    pub fn next_ty_var(&self, span: Span) -> Ty<'tcx> {
+        self.next_ty_var_with_origin(TypeVariableOrigin { span, param_def_id: None })
+    }
+
+    pub fn next_ty_var_with_origin(&self, origin: TypeVariableOrigin) -> Ty<'tcx> {
+        let vid = self.next_ty_vid_with_origin(origin);
+        Ty::new_var(self.tcx, vid)
+    }
+
     pub fn next_ty_var_in_universe(&self, span: Span, universe: ty::UniverseIndex) -> Ty<'tcx> {
-        let vid = self.next_ty_var_id_in_universe(span, universe);
+        let vid = self.next_ty_vid_in_universe(span, universe);
         Ty::new_var(self.tcx, vid)
     }
 
diff --git a/compiler/rustc_interface/Cargo.toml b/compiler/rustc_interface/Cargo.toml
index 473ac5e0cea..40152e78f8a 100644
--- a/compiler/rustc_interface/Cargo.toml
+++ b/compiler/rustc_interface/Cargo.toml
@@ -46,7 +46,7 @@ rustc_thread_pool = { path = "../rustc_thread_pool" }
 rustc_trait_selection = { path = "../rustc_trait_selection" }
 rustc_traits = { path = "../rustc_traits" }
 rustc_ty_utils = { path = "../rustc_ty_utils" }
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
 
 [dev-dependencies]
diff --git a/compiler/rustc_interface/src/interface.rs b/compiler/rustc_interface/src/interface.rs
index c46e879b976..8f131f45bbd 100644
--- a/compiler/rustc_interface/src/interface.rs
+++ b/compiler/rustc_interface/src/interface.rs
@@ -285,7 +285,9 @@ pub(crate) fn parse_check_cfg(dcx: DiagCtxtHandle<'_>, specs: Vec<String>) -> Ch
                     .expecteds
                     .entry(name.name)
                     .and_modify(|v| match v {
-                        ExpectedValues::Some(v) if !values_any_specified => {
+                        ExpectedValues::Some(v) if !values_any_specified =>
+                        {
+                            #[allow(rustc::potential_query_instability)]
                             v.extend(values.clone())
                         }
                         ExpectedValues::Some(_) => *v = ExpectedValues::Any,
diff --git a/compiler/rustc_interface/src/passes.rs b/compiler/rustc_interface/src/passes.rs
index 3ba224723e3..bc5ef04079e 100644
--- a/compiler/rustc_interface/src/passes.rs
+++ b/compiler/rustc_interface/src/passes.rs
@@ -6,6 +6,7 @@ use std::sync::{Arc, LazyLock, OnceLock};
 use std::{env, fs, iter};
 
 use rustc_ast as ast;
+use rustc_attr_parsing::{AttributeParser, ShouldEmit, validate_attr};
 use rustc_codegen_ssa::traits::CodegenBackend;
 use rustc_data_structures::jobserver::Proxy;
 use rustc_data_structures::steal::Steal;
@@ -15,6 +16,7 @@ use rustc_errors::timings::TimingSection;
 use rustc_expand::base::{ExtCtxt, LintStoreExpand};
 use rustc_feature::Features;
 use rustc_fs_util::try_canonicalize;
+use rustc_hir::attrs::AttributeKind;
 use rustc_hir::def_id::{LOCAL_CRATE, StableCrateId, StableCrateIdMap};
 use rustc_hir::definitions::Definitions;
 use rustc_incremental::setup_dep_graph;
@@ -25,9 +27,7 @@ use rustc_middle::arena::Arena;
 use rustc_middle::dep_graph::DepsType;
 use rustc_middle::ty::{self, CurrentGcx, GlobalCtxt, RegisteredTools, TyCtxt};
 use rustc_middle::util::Providers;
-use rustc_parse::{
-    new_parser_from_file, new_parser_from_source_str, unwrap_or_emit_fatal, validate_attr,
-};
+use rustc_parse::{new_parser_from_file, new_parser_from_source_str, unwrap_or_emit_fatal};
 use rustc_passes::{abi_test, input_stats, layout_test};
 use rustc_resolve::{Resolver, ResolverOutputs};
 use rustc_session::config::{CrateType, Input, OutFileName, OutputFilenames, OutputType};
@@ -1081,7 +1081,8 @@ fn run_required_analyses(tcx: TyCtxt<'_>) {
             if !tcx.is_typeck_child(def_id.to_def_id()) {
                 // Child unsafety and borrowck happens together with the parent
                 tcx.ensure_ok().check_unsafety(def_id);
-                tcx.ensure_ok().mir_borrowck(def_id)
+                tcx.ensure_ok().mir_borrowck(def_id);
+                tcx.ensure_ok().check_transmutes(def_id);
             }
             tcx.ensure_ok().has_ffi_unwind_calls(def_id);
 
@@ -1244,8 +1245,7 @@ pub fn get_crate_name(sess: &Session, krate_attrs: &[ast::Attribute]) -> Symbol
     // in all code paths that require the crate name very early on, namely before
     // macro expansion.
 
-    let attr_crate_name =
-        validate_and_find_value_str_builtin_attr(sym::crate_name, sess, krate_attrs);
+    let attr_crate_name = parse_crate_name(sess, krate_attrs, ShouldEmit::EarlyFatal);
 
     let validate = |name, span| {
         rustc_session::output::validate_crate_name(sess, name, span);
@@ -1283,6 +1283,28 @@ pub fn get_crate_name(sess: &Session, krate_attrs: &[ast::Attribute]) -> Symbol
     sym::rust_out
 }
 
+pub(crate) fn parse_crate_name(
+    sess: &Session,
+    attrs: &[ast::Attribute],
+    emit_errors: ShouldEmit,
+) -> Option<(Symbol, Span)> {
+    let rustc_hir::Attribute::Parsed(AttributeKind::CrateName { name, name_span, .. }) =
+        AttributeParser::parse_limited_should_emit(
+            sess,
+            &attrs,
+            sym::crate_name,
+            DUMMY_SP,
+            rustc_ast::node_id::CRATE_NODE_ID,
+            None,
+            emit_errors,
+        )?
+    else {
+        unreachable!("crate_name is the only attr we could've parsed here");
+    };
+
+    Some((name, name_span))
+}
+
 fn get_recursion_limit(krate_attrs: &[ast::Attribute], sess: &Session) -> Limit {
     // We don't permit macro calls inside of the attribute (e.g., #![recursion_limit = `expand!()`])
     // because that would require expanding this while in the middle of expansion, which needs to
diff --git a/compiler/rustc_interface/src/tests.rs b/compiler/rustc_interface/src/tests.rs
index 16474b231e0..7730bddc0f1 100644
--- a/compiler/rustc_interface/src/tests.rs
+++ b/compiler/rustc_interface/src/tests.rs
@@ -8,6 +8,7 @@ use rustc_abi::Align;
 use rustc_data_structures::profiling::TimePassesFormat;
 use rustc_errors::emitter::HumanReadableErrorType;
 use rustc_errors::{ColorConfig, registry};
+use rustc_hir::attrs::NativeLibKind;
 use rustc_session::config::{
     AutoDiff, BranchProtection, CFGuard, Cfg, CollapseMacroDebuginfo, CoverageLevel,
     CoverageOptions, DebugInfo, DumpMonoStatsFormat, ErrorOutputType, ExternEntry, ExternLocation,
@@ -20,7 +21,7 @@ use rustc_session::config::{
 };
 use rustc_session::lint::Level;
 use rustc_session::search_paths::SearchPath;
-use rustc_session::utils::{CanonicalizedPath, NativeLib, NativeLibKind};
+use rustc_session::utils::{CanonicalizedPath, NativeLib};
 use rustc_session::{CompilerIO, EarlyDiagCtxt, Session, build_session, getopts};
 use rustc_span::edition::{DEFAULT_EDITION, Edition};
 use rustc_span::source_map::{RealFileLoader, SourceMapInputs};
@@ -689,6 +690,7 @@ fn test_unstable_options_tracking_hash() {
     // Make sure that changing an [UNTRACKED] option leaves the hash unchanged.
     // tidy-alphabetical-start
     untracked!(assert_incr_state, Some(String::from("loaded")));
+    untracked!(codegen_source_order, true);
     untracked!(deduplicate_diagnostics, false);
     untracked!(dump_dep_graph, true);
     untracked!(dump_mir, Some(String::from("abc")));
@@ -806,6 +808,7 @@ fn test_unstable_options_tracking_hash() {
     tracked!(hint_mostly_unused, true);
     tracked!(human_readable_cgu_names, true);
     tracked!(incremental_ignore_spans, true);
+    tracked!(indirect_branch_cs_prefix, true);
     tracked!(inline_mir, Some(true));
     tracked!(inline_mir_hint_threshold, Some(123));
     tracked!(inline_mir_threshold, Some(123));
diff --git a/compiler/rustc_interface/src/util.rs b/compiler/rustc_interface/src/util.rs
index 0ca4fcc66ca..04006f3e446 100644
--- a/compiler/rustc_interface/src/util.rs
+++ b/compiler/rustc_interface/src/util.rs
@@ -5,14 +5,15 @@ use std::sync::{Arc, OnceLock};
 use std::{env, thread};
 
 use rustc_ast as ast;
+use rustc_attr_parsing::{ShouldEmit, validate_attr};
 use rustc_codegen_ssa::traits::CodegenBackend;
 use rustc_data_structures::jobserver::Proxy;
 use rustc_data_structures::sync;
+use rustc_errors::LintBuffer;
 use rustc_metadata::{DylibError, load_symbol_from_dylib};
 use rustc_middle::ty::CurrentGcx;
-use rustc_parse::validate_attr;
 use rustc_session::config::{Cfg, OutFileName, OutputFilenames, OutputTypes, Sysroot, host_tuple};
-use rustc_session::lint::{self, BuiltinLintDiag, LintBuffer};
+use rustc_session::lint::{self, BuiltinLintDiag};
 use rustc_session::output::{CRATE_TYPES, categorize_crate_type};
 use rustc_session::{EarlyDiagCtxt, Session, filesearch};
 use rustc_span::edit_distance::find_best_match_for_name;
@@ -23,6 +24,7 @@ use rustc_target::spec::Target;
 use tracing::info;
 
 use crate::errors;
+use crate::passes::parse_crate_name;
 
 /// Function pointer type that constructs a new CodegenBackend.
 type MakeBackendFn = fn() -> Box<dyn CodegenBackend>;
@@ -519,11 +521,10 @@ pub fn build_output_filenames(attrs: &[ast::Attribute], sess: &Session) -> Outpu
         sess.dcx().emit_fatal(errors::MultipleOutputTypesToStdout);
     }
 
-    let crate_name = sess
-        .opts
-        .crate_name
-        .clone()
-        .or_else(|| rustc_attr_parsing::find_crate_name(attrs).map(|n| n.to_string()));
+    let crate_name =
+        sess.opts.crate_name.clone().or_else(|| {
+            parse_crate_name(sess, attrs, ShouldEmit::Nothing).map(|i| i.0.to_string())
+        });
 
     match sess.io.output_file {
         None => {
diff --git a/compiler/rustc_lexer/Cargo.toml b/compiler/rustc_lexer/Cargo.toml
index 448a50faf45..e0019fb1821 100644
--- a/compiler/rustc_lexer/Cargo.toml
+++ b/compiler/rustc_lexer/Cargo.toml
@@ -14,13 +14,9 @@ Rust lexer used by rustc. No stability guarantees are provided.
 
 # Note that this crate purposefully does not depend on other rustc crates
 [dependencies]
-memchr = "2.7.4"
+memchr.workspace = true
+unicode-properties = { version = "0.1.0", default-features = false, features = ["emoji"] }
 unicode-xid = "0.2.0"
 
-[dependencies.unicode-properties]
-version = "0.1.0"
-default-features = false
-features = ["emoji"]
-
 [dev-dependencies]
 expect-test = "1.4.0"
diff --git a/compiler/rustc_lexer/src/lib.rs b/compiler/rustc_lexer/src/lib.rs
index e80196ed567..483cc3e93dc 100644
--- a/compiler/rustc_lexer/src/lib.rs
+++ b/compiler/rustc_lexer/src/lib.rs
@@ -540,11 +540,11 @@ impl Cursor<'_> {
         // whitespace between the opening and the infostring.
         self.eat_while(|ch| ch != '\n' && is_whitespace(ch));
 
-        // copied from `eat_identifier`, but allows `.` in infostring to allow something like
+        // copied from `eat_identifier`, but allows `-` and `.` in infostring to allow something like
         // `---Cargo.toml` as a valid opener
         if is_id_start(self.first()) {
             self.bump();
-            self.eat_while(|c| is_id_continue(c) || c == '.');
+            self.eat_while(|c| is_id_continue(c) || c == '-' || c == '.');
         }
 
         self.eat_while(|ch| ch != '\n' && is_whitespace(ch));
diff --git a/compiler/rustc_lint/Cargo.toml b/compiler/rustc_lint/Cargo.toml
index 7718f16984d..7900e4b9ab2 100644
--- a/compiler/rustc_lint/Cargo.toml
+++ b/compiler/rustc_lint/Cargo.toml
@@ -24,6 +24,6 @@ rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 rustc_trait_selection = { path = "../rustc_trait_selection" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-tracing = "0.1"
+tracing.workspace = true
 unicode-security = "0.1.0"
 # tidy-alphabetical-end
diff --git a/compiler/rustc_lint/messages.ftl b/compiler/rustc_lint/messages.ftl
index 776d8d35e05..417e5a97069 100644
--- a/compiler/rustc_lint/messages.ftl
+++ b/compiler/rustc_lint/messages.ftl
@@ -205,8 +205,6 @@ lint_confusable_identifier_pair = found both `{$existing_sym}` and `{$sym}` as i
     .current_use = this identifier can be confused with `{$existing_sym}`
     .other_use = other identifier used here
 
-lint_custom_inner_attribute_unstable = custom inner attributes are unstable
-
 lint_dangling_pointers_from_locals = a dangling pointer will be produced because the local variable `{$local_var_name}` will be dropped
     .ret_ty = return type of the {$fn_kind} is `{$ret_ty}`
     .local_var = `{$local_var_name}` is part the {$fn_kind} and will be dropped at the end of the {$fn_kind}
@@ -271,10 +269,6 @@ lint_expectation = this lint expectation is unfulfilled
 lint_extern_crate_not_idiomatic = `extern crate` is not idiomatic in the new edition
     .suggestion = convert it to a `use`
 
-lint_extern_without_abi = `extern` declarations without an explicit ABI are deprecated
-    .label = ABI should be specified here
-    .suggestion = explicitly specify the {$default_abi} ABI
-
 lint_for_loops_over_fallibles =
     for loop over {$article} `{$ref_prefix}{$ty}`. This is more readably written as an `if let` statement
     .suggestion = consider using `if let` to clear intent
@@ -294,19 +288,6 @@ lint_hidden_glob_reexport = private item shadows public glob re-export
 
 lint_hidden_lifetime_parameters = hidden lifetime parameters in types are deprecated
 
-lint_hidden_unicode_codepoints = unicode codepoint changing visible direction of text present in {$label}
-    .label = this {$label} contains {$count ->
-        [one] an invisible
-        *[other] invisible
-    } unicode text flow control {$count ->
-        [one] codepoint
-        *[other] codepoints
-    }
-    .note = these kind of unicode codepoints change the way text flows on applications that support them, but can cause confusion because they change the order of characters on the screen
-    .suggestion_remove = if their presence wasn't intentional, you can remove them
-    .suggestion_escape = if you want to keep them but make them visible in your source code, you can escape them
-    .no_suggestion_note_escape = if you want to keep them but make them visible in your source code, you can escape them: {$escaped}
-
 lint_identifier_non_ascii_char = identifier contains non-ASCII characters
 
 lint_identifier_uncommon_codepoints = identifier contains {$codepoints_len ->
@@ -431,8 +412,6 @@ lint_improper_ctypes_union_non_exhaustive = this union is non-exhaustive
 lint_incomplete_include =
     include macro expected single expression in source
 
-lint_inner_macro_attribute_unstable = inner macro attributes are unstable
-
 lint_invalid_asm_label_binary = avoid using labels containing only the digits `0` and `1` in inline assembly
     .label = use a different label that doesn't start with `0` or `1`
     .help = start numbering with `2` instead
@@ -483,6 +462,14 @@ lint_invalid_reference_casting_note_book = for more information, visit <https://
 
 lint_invalid_reference_casting_note_ty_has_interior_mutability = even for types with interior mutability, the only legal way to obtain a mutable pointer from a shared reference is through `UnsafeCell::get`
 
+lint_int_to_ptr_transmutes = transmuting an integer to a pointer creates a pointer without provenance
+    .note = this is dangerous because dereferencing the resulting pointer is undefined behavior
+    .note_exposed_provenance = exposed provenance semantics can be used to create a pointer based on some previously exposed provenance
+    .help_transmute = for more information about transmute, see <https://doc.rust-lang.org/std/mem/fn.transmute.html#transmutation-between-pointers-and-integers>
+    .help_exposed_provenance = for more information about exposed provenance, see <https://doc.rust-lang.org/std/ptr/index.html#exposed-provenance>
+    .suggestion_with_exposed_provenance = use `std::ptr::with_exposed_provenance{$suffix}` instead to use a previously exposed provenance
+    .suggestion_without_provenance_mut = if you truly mean to create a pointer without provenance, use `std::ptr::without_provenance_mut`
+
 lint_legacy_derive_helpers = derive helper attribute is used before it is introduced
     .label = the attribute is introduced here
 
@@ -732,7 +719,7 @@ lint_pattern_in_foreign = patterns aren't allowed in foreign function declaratio
 lint_private_extern_crate_reexport = extern crate `{$ident}` is private and cannot be re-exported
     .suggestion = consider making the `extern crate` item publicly accessible
 
-lint_proc_macro_derive_resolution_fallback = cannot find {$ns} `{$ident}` in this scope
+lint_proc_macro_derive_resolution_fallback = cannot find {$ns_descr} `{$ident}` in this scope
     .label = names from parent modules are not accessible without an explicit import
 
 lint_query_instability = using `{$query}` can result in unstable query results
@@ -870,10 +857,6 @@ lint_undropped_manually_drops = calls to `std::mem::drop` with `std::mem::Manual
     .label = argument has type `{$arg_ty}`
     .suggestion = use `std::mem::ManuallyDrop::into_inner` to get the inner value
 
-lint_unexpected_builtin_cfg = unexpected `--cfg {$cfg}` flag
-    .controlled_by = config `{$cfg_name}` is only supposed to be controlled by `{$controlled_by}`
-    .incoherent = manually setting a built-in cfg can and does create incoherent behaviors
-
 lint_unexpected_cfg_add_build_rs_println = or consider adding `{$build_rs_println}` to the top of the `build.rs`
 lint_unexpected_cfg_add_cargo_feature = consider using a Cargo feature instead
 lint_unexpected_cfg_add_cargo_toml_lint_cfg = or consider adding in `Cargo.toml` the `check-cfg` lint config for the lint:{$cargo_toml_lint_cfg}
@@ -983,6 +966,7 @@ lint_unused_allocation_mut = unnecessary allocation, use `&mut` instead
 
 lint_unused_builtin_attribute = unused attribute `{$attr_name}`
     .note = the built-in attribute `{$attr_name}` will be ignored, since it's applied to the macro invocation `{$macro_name}`
+    .suggestion = remove the attribute
 
 lint_unused_closure =
     unused {$pre}{$count ->
diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index 8006cfcf30f..c3c0a34df71 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -3097,7 +3097,7 @@ impl EarlyLintPass for SpecialModuleName {
             if let ast::ItemKind::Mod(
                 _,
                 ident,
-                ast::ModKind::Unloaded | ast::ModKind::Loaded(_, ast::Inline::No, _, _),
+                ast::ModKind::Unloaded | ast::ModKind::Loaded(_, ast::Inline::No { .. }, _),
             ) = item.kind
             {
                 if item.attrs.iter().any(|a| a.has_name(sym::path)) {
diff --git a/compiler/rustc_lint/src/context.rs b/compiler/rustc_lint/src/context.rs
index 11181d10af5..0669da1a025 100644
--- a/compiler/rustc_lint/src/context.rs
+++ b/compiler/rustc_lint/src/context.rs
@@ -11,7 +11,7 @@ use rustc_ast::util::parser::ExprPrecedence;
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::sync;
 use rustc_data_structures::unord::UnordMap;
-use rustc_errors::{Diag, LintDiagnostic, MultiSpan};
+use rustc_errors::{Diag, LintBuffer, LintDiagnostic, MultiSpan};
 use rustc_feature::Features;
 use rustc_hir::def::Res;
 use rustc_hir::def_id::{CrateNum, DefId};
@@ -23,8 +23,8 @@ use rustc_middle::middle::privacy::EffectiveVisibilities;
 use rustc_middle::ty::layout::{LayoutError, LayoutOfHelpers, TyAndLayout};
 use rustc_middle::ty::print::{PrintError, PrintTraitRefExt as _, Printer, with_no_trimmed_paths};
 use rustc_middle::ty::{self, GenericArg, RegisteredTools, Ty, TyCtxt, TypingEnv, TypingMode};
-use rustc_session::lint::{FutureIncompatibleInfo, Lint, LintBuffer, LintExpectationId, LintId};
-use rustc_session::{LintStoreMarker, Session};
+use rustc_session::lint::{FutureIncompatibleInfo, Lint, LintExpectationId, LintId};
+use rustc_session::{DynLintStore, Session};
 use rustc_span::edit_distance::find_best_match_for_names;
 use rustc_span::{Ident, Span, Symbol, sym};
 use tracing::debug;
@@ -62,7 +62,13 @@ pub struct LintStore {
     lint_groups: FxIndexMap<&'static str, LintGroup>,
 }
 
-impl LintStoreMarker for LintStore {}
+impl DynLintStore for LintStore {
+    fn lint_groups_iter(&self) -> Box<dyn Iterator<Item = rustc_session::LintGroup> + '_> {
+        Box::new(self.get_lint_groups().map(|(name, lints, is_externally_loaded)| {
+            rustc_session::LintGroup { name, lints, is_externally_loaded }
+        }))
+    }
+}
 
 /// The target of the `by_name` map, which accounts for renaming/deprecation.
 #[derive(Debug)]
@@ -745,41 +751,41 @@ impl<'tcx> LateContext<'tcx> {
     /// }
     /// ```
     pub fn get_def_path(&self, def_id: DefId) -> Vec<Symbol> {
-        struct AbsolutePathPrinter<'tcx> {
+        struct LintPathPrinter<'tcx> {
             tcx: TyCtxt<'tcx>,
             path: Vec<Symbol>,
         }
 
-        impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
+        impl<'tcx> Printer<'tcx> for LintPathPrinter<'tcx> {
             fn tcx(&self) -> TyCtxt<'tcx> {
                 self.tcx
             }
 
             fn print_region(&mut self, _region: ty::Region<'_>) -> Result<(), PrintError> {
-                unreachable!(); // because `path_generic_args` ignores the `GenericArgs`
+                unreachable!(); // because `print_path_with_generic_args` ignores the `GenericArgs`
             }
 
             fn print_type(&mut self, _ty: Ty<'tcx>) -> Result<(), PrintError> {
-                unreachable!(); // because `path_generic_args` ignores the `GenericArgs`
+                unreachable!(); // because `print_path_with_generic_args` ignores the `GenericArgs`
             }
 
             fn print_dyn_existential(
                 &mut self,
                 _predicates: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
             ) -> Result<(), PrintError> {
-                unreachable!(); // because `path_generic_args` ignores the `GenericArgs`
+                unreachable!(); // because `print_path_with_generic_args` ignores the `GenericArgs`
             }
 
             fn print_const(&mut self, _ct: ty::Const<'tcx>) -> Result<(), PrintError> {
-                unreachable!(); // because `path_generic_args` ignores the `GenericArgs`
+                unreachable!(); // because `print_path_with_generic_args` ignores the `GenericArgs`
             }
 
-            fn path_crate(&mut self, cnum: CrateNum) -> Result<(), PrintError> {
+            fn print_crate_name(&mut self, cnum: CrateNum) -> Result<(), PrintError> {
                 self.path = vec![self.tcx.crate_name(cnum)];
                 Ok(())
             }
 
-            fn path_qualified(
+            fn print_path_with_qualified(
                 &mut self,
                 self_ty: Ty<'tcx>,
                 trait_ref: Option<ty::TraitRef<'tcx>>,
@@ -800,7 +806,7 @@ impl<'tcx> LateContext<'tcx> {
                 })
             }
 
-            fn path_append_impl(
+            fn print_path_with_impl(
                 &mut self,
                 print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
                 self_ty: Ty<'tcx>,
@@ -825,7 +831,7 @@ impl<'tcx> LateContext<'tcx> {
                 Ok(())
             }
 
-            fn path_append(
+            fn print_path_with_simple(
                 &mut self,
                 print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
                 disambiguated_data: &DisambiguatedDefPathData,
@@ -844,7 +850,7 @@ impl<'tcx> LateContext<'tcx> {
                 Ok(())
             }
 
-            fn path_generic_args(
+            fn print_path_with_generic_args(
                 &mut self,
                 print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
                 _args: &[GenericArg<'tcx>],
@@ -853,7 +859,7 @@ impl<'tcx> LateContext<'tcx> {
             }
         }
 
-        let mut p = AbsolutePathPrinter { tcx: self.tcx, path: vec![] };
+        let mut p = LintPathPrinter { tcx: self.tcx, path: vec![] };
         p.print_def_path(def_id, &[]).unwrap();
         p.path
     }
diff --git a/compiler/rustc_lint/src/drop_forget_useless.rs b/compiler/rustc_lint/src/drop_forget_useless.rs
index 7f098893f7d..c2d137986ce 100644
--- a/compiler/rustc_lint/src/drop_forget_useless.rs
+++ b/compiler/rustc_lint/src/drop_forget_useless.rs
@@ -151,7 +151,7 @@ impl<'tcx> LateLintPass<'tcx> for DropForgetUseless {
                     && let Node::Stmt(stmt) = node
                     && let StmtKind::Semi(e) = stmt.kind
                     && e.hir_id == expr.hir_id
-                    && let Some(arg_span) = arg.span.find_ancestor_inside(expr.span)
+                    && let Some(arg_span) = arg.span.find_ancestor_inside_same_ctxt(expr.span)
                 {
                     UseLetUnderscoreIgnoreSuggestion::Suggestion {
                         start_span: expr.span.shrink_to_lo().until(arg_span),
diff --git a/compiler/rustc_lint/src/early.rs b/compiler/rustc_lint/src/early.rs
index 58205087def..dff1fc43670 100644
--- a/compiler/rustc_lint/src/early.rs
+++ b/compiler/rustc_lint/src/early.rs
@@ -7,10 +7,11 @@
 use rustc_ast::visit::{self as ast_visit, Visitor, walk_list};
 use rustc_ast::{self as ast, HasAttrs};
 use rustc_data_structures::stack::ensure_sufficient_stack;
+use rustc_errors::{BufferedEarlyLint, DecorateDiagCompat, LintBuffer};
 use rustc_feature::Features;
 use rustc_middle::ty::{RegisteredTools, TyCtxt};
 use rustc_session::Session;
-use rustc_session::lint::{BufferedEarlyLint, LintBuffer, LintPass};
+use rustc_session::lint::LintPass;
 use rustc_span::{Ident, Span};
 use tracing::debug;
 
@@ -36,8 +37,11 @@ impl<'ecx, 'tcx, T: EarlyLintPass> EarlyContextAndPass<'ecx, 'tcx, T> {
     fn check_id(&mut self, id: ast::NodeId) {
         for early_lint in self.context.buffered.take(id) {
             let BufferedEarlyLint { span, node_id: _, lint_id, diagnostic } = early_lint;
-            self.context.opt_span_lint(lint_id.lint, span, |diag| {
-                diagnostics::decorate_builtin_lint(self.context.sess(), self.tcx, diagnostic, diag);
+            self.context.opt_span_lint(lint_id.lint, span, |diag| match diagnostic {
+                DecorateDiagCompat::Builtin(b) => {
+                    diagnostics::decorate_builtin_lint(self.context.sess(), self.tcx, b, diag);
+                }
+                DecorateDiagCompat::Dynamic(d) => d.decorate_lint_box(diag),
             });
         }
     }
diff --git a/compiler/rustc_lint/src/early/diagnostics.rs b/compiler/rustc_lint/src/early/diagnostics.rs
index 1e4bc79ce70..7300490b838 100644
--- a/compiler/rustc_lint/src/early/diagnostics.rs
+++ b/compiler/rustc_lint/src/early/diagnostics.rs
@@ -64,10 +64,12 @@ pub fn decorate_builtin_lint(
             }
             .decorate_lint(diag);
         }
-        BuiltinLintDiag::ProcMacroDeriveResolutionFallback { span: macro_span, ns, ident } => {
-            lints::ProcMacroDeriveResolutionFallback { span: macro_span, ns, ident }
-                .decorate_lint(diag)
-        }
+        BuiltinLintDiag::ProcMacroDeriveResolutionFallback {
+            span: macro_span,
+            ns_descr,
+            ident,
+        } => lints::ProcMacroDeriveResolutionFallback { span: macro_span, ns_descr, ident }
+            .decorate_lint(diag),
         BuiltinLintDiag::MacroExpandedMacroExportsAccessedByAbsolutePaths(span_def) => {
             lints::MacroExpandedMacroExportsAccessedByAbsolutePaths { definition: span_def }
                 .decorate_lint(diag)
@@ -156,9 +158,6 @@ pub fn decorate_builtin_lint(
             }
             .decorate_lint(diag);
         }
-        BuiltinLintDiag::MissingAbi(label_span, default_abi) => {
-            lints::MissingAbi { span: label_span, default_abi }.decorate_lint(diag);
-        }
         BuiltinLintDiag::LegacyDeriveHelpers(label_span) => {
             lints::LegacyDeriveHelpers { span: label_span }.decorate_lint(diag);
         }
@@ -184,29 +183,14 @@ pub fn decorate_builtin_lint(
                 lints::ReservedMultihash { suggestion }.decorate_lint(diag);
             }
         }
-        BuiltinLintDiag::HiddenUnicodeCodepoints {
-            label,
-            count,
-            span_label,
-            labels,
-            escape,
-            spans,
+        BuiltinLintDiag::UnusedBuiltinAttribute {
+            attr_name,
+            macro_name,
+            invoc_span,
+            attr_span,
         } => {
-            lints::HiddenUnicodeCodepointsDiag {
-                label: &label,
-                count,
-                span_label,
-                labels: labels.map(|spans| lints::HiddenUnicodeCodepointsDiagLabels { spans }),
-                sub: if escape {
-                    lints::HiddenUnicodeCodepointsDiagSub::Escape { spans }
-                } else {
-                    lints::HiddenUnicodeCodepointsDiagSub::NoEscape { spans }
-                },
-            }
-            .decorate_lint(diag);
-        }
-        BuiltinLintDiag::UnusedBuiltinAttribute { attr_name, macro_name, invoc_span } => {
-            lints::UnusedBuiltinAttribute { invoc_span, attr_name, macro_name }.decorate_lint(diag);
+            lints::UnusedBuiltinAttribute { invoc_span, attr_name, macro_name, attr_span }
+                .decorate_lint(diag);
         }
         BuiltinLintDiag::TrailingMacro(is_trailing, name) => {
             lints::TrailingMacro { is_trailing, name }.decorate_lint(diag);
@@ -458,17 +442,8 @@ pub fn decorate_builtin_lint(
             }
             .decorate_lint(diag)
         }
-        BuiltinLintDiag::InnerAttributeUnstable { is_macro } => if is_macro {
-            lints::InnerAttributeUnstable::InnerMacroAttribute
-        } else {
-            lints::InnerAttributeUnstable::CustomInnerAttribute
-        }
-        .decorate_lint(diag),
         BuiltinLintDiag::OutOfScopeMacroCalls { span, path, location } => {
             lints::OutOfScopeMacroCalls { span, path, location }.decorate_lint(diag)
         }
-        BuiltinLintDiag::UnexpectedBuiltinCfg { cfg, cfg_name, controlled_by } => {
-            lints::UnexpectedBuiltinCfg { cfg, cfg_name, controlled_by }.decorate_lint(diag)
-        }
     }
 }
diff --git a/compiler/rustc_lint/src/foreign_modules.rs b/compiler/rustc_lint/src/foreign_modules.rs
index 759e6c927b8..3267e70f1de 100644
--- a/compiler/rustc_lint/src/foreign_modules.rs
+++ b/compiler/rustc_lint/src/foreign_modules.rs
@@ -179,7 +179,7 @@ impl ClashingExternDeclarations {
 /// symbol's name.
 fn name_of_extern_decl(tcx: TyCtxt<'_>, fi: hir::OwnerId) -> SymbolName {
     if let Some((overridden_link_name, overridden_link_name_span)) =
-        tcx.codegen_fn_attrs(fi).link_name.map(|overridden_link_name| {
+        tcx.codegen_fn_attrs(fi).symbol_name.map(|overridden_link_name| {
             // FIXME: Instead of searching through the attributes again to get span
             // information, we could have codegen_fn_attrs also give span information back for
             // where the attribute was defined. However, until this is found to be a
diff --git a/compiler/rustc_lint/src/internal.rs b/compiler/rustc_lint/src/internal.rs
index 016ff17f5d7..929fc8207b0 100644
--- a/compiler/rustc_lint/src/internal.rs
+++ b/compiler/rustc_lint/src/internal.rs
@@ -1,10 +1,10 @@
 //! Some lints that are only useful in the compiler or crates that use compiler internals, such as
 //! Clippy.
 
-use rustc_hir::HirId;
 use rustc_hir::def::Res;
 use rustc_hir::def_id::DefId;
-use rustc_middle::ty::{self, GenericArgsRef, Ty as MiddleTy};
+use rustc_hir::{Expr, ExprKind, HirId};
+use rustc_middle::ty::{self, GenericArgsRef, PredicatePolarity, Ty};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::hygiene::{ExpnKind, MacroKind};
 use rustc_span::{Span, sym};
@@ -56,25 +56,6 @@ impl LateLintPass<'_> for DefaultHashTypes {
     }
 }
 
-/// Helper function for lints that check for expressions with calls and use typeck results to
-/// get the `DefId` and `GenericArgsRef` of the function.
-fn typeck_results_of_method_fn<'tcx>(
-    cx: &LateContext<'tcx>,
-    expr: &hir::Expr<'_>,
-) -> Option<(Span, DefId, ty::GenericArgsRef<'tcx>)> {
-    match expr.kind {
-        hir::ExprKind::MethodCall(segment, ..)
-            if let Some(def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id) =>
-        {
-            Some((segment.ident.span, def_id, cx.typeck_results().node_args(expr.hir_id)))
-        }
-        _ => match cx.typeck_results().node_type(expr.hir_id).kind() {
-            &ty::FnDef(def_id, args) => Some((expr.span, def_id, args)),
-            _ => None,
-        },
-    }
-}
-
 declare_tool_lint! {
     /// The `potential_query_instability` lint detects use of methods which can lead to
     /// potential query instability, such as iterating over a `HashMap`.
@@ -101,10 +82,12 @@ declare_tool_lint! {
 
 declare_lint_pass!(QueryStability => [POTENTIAL_QUERY_INSTABILITY, UNTRACKED_QUERY_INFORMATION]);
 
-impl LateLintPass<'_> for QueryStability {
-    fn check_expr(&mut self, cx: &LateContext<'_>, expr: &hir::Expr<'_>) {
-        let Some((span, def_id, args)) = typeck_results_of_method_fn(cx, expr) else { return };
-        if let Ok(Some(instance)) = ty::Instance::try_resolve(cx.tcx, cx.typing_env(), def_id, args)
+impl<'tcx> LateLintPass<'tcx> for QueryStability {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
+        if let Some((callee_def_id, span, generic_args, _recv, _args)) =
+            get_callee_span_generic_args_and_args(cx, expr)
+            && let Ok(Some(instance)) =
+                ty::Instance::try_resolve(cx.tcx, cx.typing_env(), callee_def_id, generic_args)
         {
             let def_id = instance.def_id();
             if cx.tcx.has_attr(def_id, sym::rustc_lint_query_instability) {
@@ -113,7 +96,15 @@ impl LateLintPass<'_> for QueryStability {
                     span,
                     QueryInstability { query: cx.tcx.item_name(def_id) },
                 );
+            } else if has_unstable_into_iter_predicate(cx, callee_def_id, generic_args) {
+                let call_span = span.with_hi(expr.span.hi());
+                cx.emit_span_lint(
+                    POTENTIAL_QUERY_INSTABILITY,
+                    call_span,
+                    QueryInstability { query: sym::into_iter },
+                );
             }
+
             if cx.tcx.has_attr(def_id, sym::rustc_lint_untracked_query_information) {
                 cx.emit_span_lint(
                     UNTRACKED_QUERY_INFORMATION,
@@ -125,6 +116,69 @@ impl LateLintPass<'_> for QueryStability {
     }
 }
 
+fn has_unstable_into_iter_predicate<'tcx>(
+    cx: &LateContext<'tcx>,
+    callee_def_id: DefId,
+    generic_args: GenericArgsRef<'tcx>,
+) -> bool {
+    let Some(into_iterator_def_id) = cx.tcx.get_diagnostic_item(sym::IntoIterator) else {
+        return false;
+    };
+    let Some(into_iter_fn_def_id) = cx.tcx.lang_items().into_iter_fn() else {
+        return false;
+    };
+    let predicates = cx.tcx.predicates_of(callee_def_id).instantiate(cx.tcx, generic_args);
+    for (predicate, _) in predicates {
+        let Some(trait_pred) = predicate.as_trait_clause() else {
+            continue;
+        };
+        if trait_pred.def_id() != into_iterator_def_id
+            || trait_pred.polarity() != PredicatePolarity::Positive
+        {
+            continue;
+        }
+        // `IntoIterator::into_iter` has no additional method args.
+        let into_iter_fn_args =
+            cx.tcx.instantiate_bound_regions_with_erased(trait_pred).trait_ref.args;
+        let Ok(Some(instance)) = ty::Instance::try_resolve(
+            cx.tcx,
+            cx.typing_env(),
+            into_iter_fn_def_id,
+            into_iter_fn_args,
+        ) else {
+            continue;
+        };
+        // Does the input type's `IntoIterator` implementation have the
+        // `rustc_lint_query_instability` attribute on its `into_iter` method?
+        if cx.tcx.has_attr(instance.def_id(), sym::rustc_lint_query_instability) {
+            return true;
+        }
+    }
+    false
+}
+
+/// Checks whether an expression is a function or method call and, if so, returns its `DefId`,
+/// `Span`, `GenericArgs`, and arguments. This is a slight augmentation of a similarly named Clippy
+/// function, `get_callee_generic_args_and_args`.
+fn get_callee_span_generic_args_and_args<'tcx>(
+    cx: &LateContext<'tcx>,
+    expr: &'tcx Expr<'tcx>,
+) -> Option<(DefId, Span, GenericArgsRef<'tcx>, Option<&'tcx Expr<'tcx>>, &'tcx [Expr<'tcx>])> {
+    if let ExprKind::Call(callee, args) = expr.kind
+        && let callee_ty = cx.typeck_results().expr_ty(callee)
+        && let ty::FnDef(callee_def_id, generic_args) = callee_ty.kind()
+    {
+        return Some((*callee_def_id, callee.span, generic_args, None, args));
+    }
+    if let ExprKind::MethodCall(segment, recv, args, _) = expr.kind
+        && let Some(method_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id)
+    {
+        let generic_args = cx.typeck_results().node_args(expr.hir_id);
+        return Some((method_def_id, segment.ident.span, generic_args, Some(recv), args));
+    }
+    None
+}
+
 declare_tool_lint! {
     /// The `usage_of_ty_tykind` lint detects usages of `ty::TyKind::<kind>`,
     /// where `ty::<kind>` would suffice.
@@ -461,33 +515,22 @@ declare_tool_lint! {
 declare_lint_pass!(Diagnostics => [UNTRANSLATABLE_DIAGNOSTIC, DIAGNOSTIC_OUTSIDE_OF_IMPL]);
 
 impl LateLintPass<'_> for Diagnostics {
-    fn check_expr(&mut self, cx: &LateContext<'_>, expr: &hir::Expr<'_>) {
+    fn check_expr<'tcx>(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'tcx>) {
         let collect_args_tys_and_spans = |args: &[hir::Expr<'_>], reserve_one_extra: bool| {
             let mut result = Vec::with_capacity(args.len() + usize::from(reserve_one_extra));
             result.extend(args.iter().map(|arg| (cx.typeck_results().expr_ty(arg), arg.span)));
             result
         };
         // Only check function calls and method calls.
-        let (span, def_id, fn_gen_args, arg_tys_and_spans) = match expr.kind {
-            hir::ExprKind::Call(callee, args) => {
-                match cx.typeck_results().node_type(callee.hir_id).kind() {
-                    &ty::FnDef(def_id, fn_gen_args) => {
-                        (callee.span, def_id, fn_gen_args, collect_args_tys_and_spans(args, false))
-                    }
-                    _ => return, // occurs for fns passed as args
-                }
-            }
-            hir::ExprKind::MethodCall(_segment, _recv, args, _span) => {
-                let Some((span, def_id, fn_gen_args)) = typeck_results_of_method_fn(cx, expr)
-                else {
-                    return;
-                };
-                let mut args = collect_args_tys_and_spans(args, true);
-                args.insert(0, (cx.tcx.types.self_param, _recv.span)); // dummy inserted for `self`
-                (span, def_id, fn_gen_args, args)
-            }
-            _ => return,
+        let Some((def_id, span, fn_gen_args, recv, args)) =
+            get_callee_span_generic_args_and_args(cx, expr)
+        else {
+            return;
         };
+        let mut arg_tys_and_spans = collect_args_tys_and_spans(args, recv.is_some());
+        if let Some(recv) = recv {
+            arg_tys_and_spans.insert(0, (cx.tcx.types.self_param, recv.span)); // dummy inserted for `self`
+        }
 
         Self::diagnostic_outside_of_impl(cx, span, expr.hir_id, def_id, fn_gen_args);
         Self::untranslatable_diagnostic(cx, def_id, &arg_tys_and_spans);
@@ -496,7 +539,7 @@ impl LateLintPass<'_> for Diagnostics {
 
 impl Diagnostics {
     // Is the type `{D,Subd}iagMessage`?
-    fn is_diag_message<'cx>(cx: &LateContext<'cx>, ty: MiddleTy<'cx>) -> bool {
+    fn is_diag_message<'cx>(cx: &LateContext<'cx>, ty: Ty<'cx>) -> bool {
         if let Some(adt_def) = ty.ty_adt_def()
             && let Some(name) = cx.tcx.get_diagnostic_name(adt_def.did())
             && matches!(name, sym::DiagMessage | sym::SubdiagMessage)
@@ -510,7 +553,7 @@ impl Diagnostics {
     fn untranslatable_diagnostic<'cx>(
         cx: &LateContext<'cx>,
         def_id: DefId,
-        arg_tys_and_spans: &[(MiddleTy<'cx>, Span)],
+        arg_tys_and_spans: &[(Ty<'cx>, Span)],
     ) {
         let fn_sig = cx.tcx.fn_sig(def_id).instantiate_identity().skip_binder();
         let predicates = cx.tcx.predicates_of(def_id).instantiate_identity(cx.tcx).predicates;
diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
index f06757b3c23..bdbac7fc4d1 100644
--- a/compiler/rustc_lint/src/lib.rs
+++ b/compiler/rustc_lint/src/lib.rs
@@ -133,10 +133,9 @@ pub use early::{EarlyCheckNode, check_ast_node};
 pub use late::{check_crate, late_lint_mod, unerased_lint_store};
 pub use levels::LintLevelsBuilder;
 pub use passes::{EarlyLintPass, LateLintPass};
+pub use rustc_errors::BufferedEarlyLint;
 pub use rustc_session::lint::Level::{self, *};
-pub use rustc_session::lint::{
-    BufferedEarlyLint, FutureIncompatibleInfo, Lint, LintId, LintPass, LintVec,
-};
+pub use rustc_session::lint::{FutureIncompatibleInfo, Lint, LintId, LintPass, LintVec};
 
 rustc_fluent_macro::fluent_messages! { "../messages.ftl" }
 
diff --git a/compiler/rustc_lint/src/lifetime_syntax.rs b/compiler/rustc_lint/src/lifetime_syntax.rs
index 464f4fc34b9..413525eb6e5 100644
--- a/compiler/rustc_lint/src/lifetime_syntax.rs
+++ b/compiler/rustc_lint/src/lifetime_syntax.rs
@@ -214,9 +214,9 @@ impl<T> LifetimeSyntaxCategories<Vec<T>> {
         }
     }
 
-    pub fn flatten(&self) -> impl Iterator<Item = &T> {
-        let Self { hidden, elided, named } = self;
-        [hidden.iter(), elided.iter(), named.iter()].into_iter().flatten()
+    pub fn iter_unnamed(&self) -> impl Iterator<Item = &T> {
+        let Self { hidden, elided, named: _ } = self;
+        [hidden.iter(), elided.iter()].into_iter().flatten()
     }
 }
 
@@ -495,7 +495,7 @@ fn emit_mismatch_diagnostic<'tcx>(
 
     cx.emit_span_lint(
         MISMATCHED_LIFETIME_SYNTAXES,
-        inputs.flatten().copied().collect::<Vec<_>>(),
+        inputs.iter_unnamed().chain(outputs.iter_unnamed()).copied().collect::<Vec<_>>(),
         lints::MismatchedLifetimeSyntaxes { inputs, outputs, suggestions },
     );
 }
diff --git a/compiler/rustc_lint/src/lints.rs b/compiler/rustc_lint/src/lints.rs
index ba0112c8ac6..56d65ed08f9 100644
--- a/compiler/rustc_lint/src/lints.rs
+++ b/compiler/rustc_lint/src/lints.rs
@@ -1,14 +1,14 @@
+// ignore-tidy-filelength
+
 #![allow(rustc::untranslatable_diagnostic)]
 use std::num::NonZero;
 
-use rustc_abi::ExternAbi;
 use rustc_errors::codes::*;
 use rustc_errors::{
     Applicability, Diag, DiagArgValue, DiagMessage, DiagStyledString, ElidedLifetimeInPathSubdiag,
     EmissionGuarantee, LintDiagnostic, MultiSpan, Subdiagnostic, SuggestionStyle,
 };
 use rustc_hir as hir;
-use rustc_hir::def::Namespace;
 use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::VisitorExt;
 use rustc_macros::{LintDiagnostic, Subdiagnostic};
@@ -817,80 +817,6 @@ pub(crate) enum InvalidReferenceCastingDiag<'tcx> {
     },
 }
 
-// hidden_unicode_codepoints.rs
-#[derive(LintDiagnostic)]
-#[diag(lint_hidden_unicode_codepoints)]
-#[note]
-pub(crate) struct HiddenUnicodeCodepointsDiag<'a> {
-    pub label: &'a str,
-    pub count: usize,
-    #[label]
-    pub span_label: Span,
-    #[subdiagnostic]
-    pub labels: Option<HiddenUnicodeCodepointsDiagLabels>,
-    #[subdiagnostic]
-    pub sub: HiddenUnicodeCodepointsDiagSub,
-}
-
-pub(crate) struct HiddenUnicodeCodepointsDiagLabels {
-    pub spans: Vec<(char, Span)>,
-}
-
-impl Subdiagnostic for HiddenUnicodeCodepointsDiagLabels {
-    fn add_to_diag<G: EmissionGuarantee>(self, diag: &mut Diag<'_, G>) {
-        for (c, span) in self.spans {
-            diag.span_label(span, format!("{c:?}"));
-        }
-    }
-}
-
-pub(crate) enum HiddenUnicodeCodepointsDiagSub {
-    Escape { spans: Vec<(char, Span)> },
-    NoEscape { spans: Vec<(char, Span)> },
-}
-
-// Used because of multiple multipart_suggestion and note
-impl Subdiagnostic for HiddenUnicodeCodepointsDiagSub {
-    fn add_to_diag<G: EmissionGuarantee>(self, diag: &mut Diag<'_, G>) {
-        match self {
-            HiddenUnicodeCodepointsDiagSub::Escape { spans } => {
-                diag.multipart_suggestion_with_style(
-                    fluent::lint_suggestion_remove,
-                    spans.iter().map(|(_, span)| (*span, "".to_string())).collect(),
-                    Applicability::MachineApplicable,
-                    SuggestionStyle::HideCodeAlways,
-                );
-                diag.multipart_suggestion(
-                    fluent::lint_suggestion_escape,
-                    spans
-                        .into_iter()
-                        .map(|(c, span)| {
-                            let c = format!("{c:?}");
-                            (span, c[1..c.len() - 1].to_string())
-                        })
-                        .collect(),
-                    Applicability::MachineApplicable,
-                );
-            }
-            HiddenUnicodeCodepointsDiagSub::NoEscape { spans } => {
-                // FIXME: in other suggestions we've reversed the inner spans of doc comments. We
-                // should do the same here to provide the same good suggestions as we do for
-                // literals above.
-                diag.arg(
-                    "escaped",
-                    spans
-                        .into_iter()
-                        .map(|(c, _)| format!("{c:?}"))
-                        .collect::<Vec<String>>()
-                        .join(", "),
-                );
-                diag.note(fluent::lint_suggestion_remove);
-                diag.note(fluent::lint_no_suggestion_note_escape);
-            }
-        }
-    }
-}
-
 // map_unit_fn.rs
 #[derive(LintDiagnostic)]
 #[diag(lint_map_unit_fn)]
@@ -1618,6 +1544,48 @@ impl<'a> LintDiagnostic<'a, ()> for DropGlue<'_> {
     }
 }
 
+// transmute.rs
+#[derive(LintDiagnostic)]
+#[diag(lint_int_to_ptr_transmutes)]
+#[note]
+#[note(lint_note_exposed_provenance)]
+#[help(lint_suggestion_without_provenance_mut)]
+#[help(lint_help_transmute)]
+#[help(lint_help_exposed_provenance)]
+pub(crate) struct IntegerToPtrTransmutes<'tcx> {
+    #[subdiagnostic]
+    pub suggestion: Option<IntegerToPtrTransmutesSuggestion<'tcx>>,
+}
+
+#[derive(Subdiagnostic)]
+pub(crate) enum IntegerToPtrTransmutesSuggestion<'tcx> {
+    #[multipart_suggestion(
+        lint_suggestion_with_exposed_provenance,
+        applicability = "machine-applicable",
+        style = "verbose"
+    )]
+    ToPtr {
+        dst: Ty<'tcx>,
+        suffix: &'static str,
+        #[suggestion_part(code = "std::ptr::with_exposed_provenance{suffix}::<{dst}>(")]
+        start_call: Span,
+    },
+    #[multipart_suggestion(
+        lint_suggestion_with_exposed_provenance,
+        applicability = "machine-applicable",
+        style = "verbose"
+    )]
+    ToRef {
+        dst: Ty<'tcx>,
+        suffix: &'static str,
+        ref_mutbl: &'static str,
+        #[suggestion_part(
+            code = "&{ref_mutbl}*std::ptr::with_exposed_provenance{suffix}::<{dst}>("
+        )]
+        start_call: Span,
+    },
+}
+
 // types.rs
 #[derive(LintDiagnostic)]
 #[diag(lint_range_endpoint_out_of_range)]
@@ -2568,16 +2536,6 @@ pub(crate) mod unexpected_cfg_value {
 }
 
 #[derive(LintDiagnostic)]
-#[diag(lint_unexpected_builtin_cfg)]
-#[note(lint_controlled_by)]
-#[note(lint_incoherent)]
-pub(crate) struct UnexpectedBuiltinCfg {
-    pub(crate) cfg: String,
-    pub(crate) cfg_name: Symbol,
-    pub(crate) controlled_by: &'static str,
-}
-
-#[derive(LintDiagnostic)]
 #[diag(lint_macro_use_deprecated)]
 #[help]
 pub(crate) struct MacroUseDeprecated;
@@ -2691,14 +2649,6 @@ pub(crate) struct IllFormedAttributeInput {
 }
 
 #[derive(LintDiagnostic)]
-pub(crate) enum InnerAttributeUnstable {
-    #[diag(lint_inner_macro_attribute_unstable)]
-    InnerMacroAttribute,
-    #[diag(lint_custom_inner_attribute_unstable)]
-    CustomInnerAttribute,
-}
-
-#[derive(LintDiagnostic)]
 #[diag(lint_unknown_diagnostic_attribute)]
 pub(crate) struct UnknownDiagnosticAttribute {
     #[subdiagnostic]
@@ -2769,7 +2719,7 @@ pub(crate) struct AbsPathWithModuleSugg {
 pub(crate) struct ProcMacroDeriveResolutionFallback {
     #[label]
     pub span: Span,
-    pub ns: Namespace,
+    pub ns_descr: &'static str,
     pub ident: Ident,
 }
 
@@ -2891,14 +2841,6 @@ pub(crate) struct PatternsInFnsWithoutBodySub {
 }
 
 #[derive(LintDiagnostic)]
-#[diag(lint_extern_without_abi)]
-pub(crate) struct MissingAbi {
-    #[suggestion(code = "extern {default_abi}", applicability = "machine-applicable")]
-    pub span: Span,
-    pub default_abi: ExternAbi,
-}
-
-#[derive(LintDiagnostic)]
 #[diag(lint_legacy_derive_helpers)]
 pub(crate) struct LegacyDeriveHelpers {
     #[label]
@@ -2938,9 +2880,10 @@ pub(crate) struct RawPrefix {
 pub(crate) struct UnusedBuiltinAttribute {
     #[note]
     pub invoc_span: Span,
-
     pub attr_name: Symbol,
     pub macro_name: String,
+    #[suggestion(code = "", applicability = "machine-applicable", style = "tool-only")]
+    pub attr_span: Span,
 }
 
 #[derive(LintDiagnostic)]
diff --git a/compiler/rustc_lint/src/non_local_def.rs b/compiler/rustc_lint/src/non_local_def.rs
index 2dd3425e66c..dca22b986ff 100644
--- a/compiler/rustc_lint/src/non_local_def.rs
+++ b/compiler/rustc_lint/src/non_local_def.rs
@@ -5,7 +5,7 @@ use rustc_hir::{Body, HirId, Item, ItemKind, Node, Path, TyKind};
 use rustc_middle::ty::TyCtxt;
 use rustc_session::{declare_lint, impl_lint_pass};
 use rustc_span::def_id::{DefId, LOCAL_CRATE};
-use rustc_span::{ExpnKind, MacroKind, Span, kw, sym};
+use rustc_span::{ExpnKind, Span, kw, sym};
 
 use crate::lints::{NonLocalDefinitionsCargoUpdateNote, NonLocalDefinitionsDiag};
 use crate::{LateContext, LateLintPass, LintContext, fluent_generated as fluent};
@@ -240,7 +240,7 @@ impl<'tcx> LateLintPass<'tcx> for NonLocalDefinitions {
                     },
                 )
             }
-            ItemKind::Macro(_, _macro, MacroKind::Bang)
+            ItemKind::Macro(_, _macro, _kinds)
                 if cx.tcx.has_attr(item.owner_id.def_id, sym::macro_export) =>
             {
                 cx.emit_span_lint(
diff --git a/compiler/rustc_lint/src/nonstandard_style.rs b/compiler/rustc_lint/src/nonstandard_style.rs
index 8fafaa33d0c..65075cfecfa 100644
--- a/compiler/rustc_lint/src/nonstandard_style.rs
+++ b/compiler/rustc_lint/src/nonstandard_style.rs
@@ -5,7 +5,7 @@ use rustc_hir::attrs::{AttributeKind, ReprAttr};
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::{FnKind, Visitor};
-use rustc_hir::{AttrArgs, AttrItem, Attribute, GenericParamKind, PatExprKind, PatKind, find_attr};
+use rustc_hir::{Attribute, GenericParamKind, PatExprKind, PatKind, find_attr};
 use rustc_middle::hir::nested_filter::All;
 use rustc_middle::ty;
 use rustc_session::config::CrateType;
@@ -343,35 +343,27 @@ impl<'tcx> LateLintPass<'tcx> for NonSnakeCase {
         let crate_ident = if let Some(name) = &cx.tcx.sess.opts.crate_name {
             Some(Ident::from_str(name))
         } else {
-            ast::attr::find_by_name(cx.tcx.hir_attrs(hir::CRATE_HIR_ID), sym::crate_name).and_then(
-                |attr| {
-                    if let Attribute::Unparsed(n) = attr
-                        && let AttrItem { args: AttrArgs::Eq { eq_span: _, expr: lit }, .. } =
-                            n.as_ref()
-                        && let ast::LitKind::Str(name, ..) = lit.kind
-                    {
-                        // Discard the double quotes surrounding the literal.
-                        let sp = cx
-                            .sess()
-                            .source_map()
-                            .span_to_snippet(lit.span)
-                            .ok()
-                            .and_then(|snippet| {
-                                let left = snippet.find('"')?;
-                                let right = snippet.rfind('"').map(|pos| snippet.len() - pos)?;
-
-                                Some(
-                                    lit.span
-                                        .with_lo(lit.span.lo() + BytePos(left as u32 + 1))
-                                        .with_hi(lit.span.hi() - BytePos(right as u32)),
-                                )
-                            })
-                            .unwrap_or(lit.span);
-
-                        Some(Ident::new(name, sp))
-                    } else {
-                        None
-                    }
+            find_attr!(cx.tcx.hir_attrs(hir::CRATE_HIR_ID), AttributeKind::CrateName{name, name_span,..} => (name, name_span)).map(
+                |(&name, &span)| {
+                    // Discard the double quotes surrounding the literal.
+                    let sp = cx
+                        .sess()
+                        .source_map()
+                        .span_to_snippet(span)
+                        .ok()
+                        .and_then(|snippet| {
+                            let left = snippet.find('"')?;
+                            let right = snippet.rfind('"').map(|pos| snippet.len() - pos)?;
+
+                            Some(
+                                span
+                                    .with_lo(span.lo() + BytePos(left as u32 + 1))
+                                    .with_hi(span.hi() - BytePos(right as u32)),
+                            )
+                        })
+                        .unwrap_or(span);
+
+                    Ident::new(name, sp)
                 },
             )
         };
diff --git a/compiler/rustc_lint/src/pass_by_value.rs b/compiler/rustc_lint/src/pass_by_value.rs
index 4f65acd8001..29006732aad 100644
--- a/compiler/rustc_lint/src/pass_by_value.rs
+++ b/compiler/rustc_lint/src/pass_by_value.rs
@@ -24,10 +24,8 @@ impl<'tcx> LateLintPass<'tcx> for PassByValue {
     fn check_ty(&mut self, cx: &LateContext<'_>, ty: &'tcx hir::Ty<'tcx, AmbigArg>) {
         match &ty.kind {
             TyKind::Ref(_, hir::MutTy { ty: inner_ty, mutbl: hir::Mutability::Not }) => {
-                if let Some(impl_did) = cx.tcx.impl_of_assoc(ty.hir_id.owner.to_def_id()) {
-                    if cx.tcx.impl_trait_ref(impl_did).is_some() {
-                        return;
-                    }
+                if cx.tcx.trait_impl_of_assoc(ty.hir_id.owner.to_def_id()).is_some() {
+                    return;
                 }
                 if let Some(t) = path_for_pass_by_value(cx, inner_ty) {
                     cx.emit_span_lint(
diff --git a/compiler/rustc_lint/src/transmute.rs b/compiler/rustc_lint/src/transmute.rs
index bc1d4587d07..98510eea73b 100644
--- a/compiler/rustc_lint/src/transmute.rs
+++ b/compiler/rustc_lint/src/transmute.rs
@@ -1,3 +1,4 @@
+use rustc_ast::LitKind;
 use rustc_errors::Applicability;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::LocalDefId;
@@ -7,6 +8,7 @@ use rustc_middle::ty::{self, Ty};
 use rustc_session::{declare_lint, impl_lint_pass};
 use rustc_span::sym;
 
+use crate::lints::{IntegerToPtrTransmutes, IntegerToPtrTransmutesSuggestion};
 use crate::{LateContext, LateLintPass};
 
 declare_lint! {
@@ -67,9 +69,44 @@ declare_lint! {
     "detects transmutes that can also be achieved by other operations"
 }
 
+declare_lint! {
+    /// The `integer_to_ptr_transmutes` lint detects integer to pointer
+    /// transmutes where the resulting pointers are undefined behavior to dereference.
+    ///
+    /// ### Example
+    ///
+    /// ```rust
+    /// fn foo(a: usize) -> *const u8 {
+    ///    unsafe {
+    ///        std::mem::transmute::<usize, *const u8>(a)
+    ///    }
+    /// }
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// Any attempt to use the resulting pointers are undefined behavior as the resulting
+    /// pointers won't have any provenance.
+    ///
+    /// Alternatively, [`std::ptr::with_exposed_provenance`] should be used, as they do not
+    /// carry the provenance requirement. If wanting to create pointers without provenance
+    /// [`std::ptr::without_provenance`] should be used instead.
+    ///
+    /// See [`std::mem::transmute`] in the reference for more details.
+    ///
+    /// [`std::mem::transmute`]: https://doc.rust-lang.org/std/mem/fn.transmute.html
+    /// [`std::ptr::with_exposed_provenance`]: https://doc.rust-lang.org/std/ptr/fn.with_exposed_provenance.html
+    /// [`std::ptr::without_provenance`]: https://doc.rust-lang.org/std/ptr/fn.without_provenance.html
+    pub INTEGER_TO_PTR_TRANSMUTES,
+    Warn,
+    "detects integer to pointer transmutes",
+}
+
 pub(crate) struct CheckTransmutes;
 
-impl_lint_pass!(CheckTransmutes => [PTR_TO_INTEGER_TRANSMUTE_IN_CONSTS, UNNECESSARY_TRANSMUTES]);
+impl_lint_pass!(CheckTransmutes => [PTR_TO_INTEGER_TRANSMUTE_IN_CONSTS, UNNECESSARY_TRANSMUTES, INTEGER_TO_PTR_TRANSMUTES]);
 
 impl<'tcx> LateLintPass<'tcx> for CheckTransmutes {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'tcx>) {
@@ -94,9 +131,68 @@ impl<'tcx> LateLintPass<'tcx> for CheckTransmutes {
 
         check_ptr_transmute_in_const(cx, expr, body_owner_def_id, const_context, src, dst);
         check_unnecessary_transmute(cx, expr, callee, arg, const_context, src, dst);
+        check_int_to_ptr_transmute(cx, expr, arg, src, dst);
     }
 }
 
+/// Check for transmutes from integer to pointers (*const/*mut and &/&mut).
+///
+/// Using the resulting pointers would be undefined behavior.
+fn check_int_to_ptr_transmute<'tcx>(
+    cx: &LateContext<'tcx>,
+    expr: &'tcx hir::Expr<'tcx>,
+    arg: &'tcx hir::Expr<'tcx>,
+    src: Ty<'tcx>,
+    dst: Ty<'tcx>,
+) {
+    if !matches!(src.kind(), ty::Uint(_) | ty::Int(_)) {
+        return;
+    }
+    let (ty::Ref(_, inner_ty, mutbl) | ty::RawPtr(inner_ty, mutbl)) = dst.kind() else {
+        return;
+    };
+    // bail-out if the argument is literal 0 as we have other lints for those cases
+    if matches!(arg.kind, hir::ExprKind::Lit(hir::Lit { node: LitKind::Int(v, _), .. }) if v == 0) {
+        return;
+    }
+    // bail-out if the inner type is a ZST
+    let Ok(layout_inner_ty) = cx.tcx.layout_of(cx.typing_env().as_query_input(*inner_ty)) else {
+        return;
+    };
+    if layout_inner_ty.is_1zst() {
+        return;
+    }
+
+    let suffix = if mutbl.is_mut() { "_mut" } else { "" };
+    cx.tcx.emit_node_span_lint(
+        INTEGER_TO_PTR_TRANSMUTES,
+        expr.hir_id,
+        expr.span,
+        IntegerToPtrTransmutes {
+            suggestion: if layout_inner_ty.is_sized() {
+                Some(if dst.is_ref() {
+                    IntegerToPtrTransmutesSuggestion::ToRef {
+                        dst: *inner_ty,
+                        suffix,
+                        ref_mutbl: mutbl.prefix_str(),
+                        start_call: expr.span.shrink_to_lo().until(arg.span),
+                    }
+                } else {
+                    IntegerToPtrTransmutesSuggestion::ToPtr {
+                        dst: *inner_ty,
+                        suffix,
+                        start_call: expr.span.shrink_to_lo().until(arg.span),
+                    }
+                })
+            } else {
+                // We can't suggest using `with_exposed_provenance` for unsized type
+                // so don't suggest anything.
+                None
+            },
+        },
+    );
+}
+
 /// Check for transmutes that exhibit undefined behavior.
 /// For example, transmuting pointers to integers in a const context.
 ///
diff --git a/compiler/rustc_lint/src/types.rs b/compiler/rustc_lint/src/types.rs
index b0afc333ebe..f8a692313f0 100644
--- a/compiler/rustc_lint/src/types.rs
+++ b/compiler/rustc_lint/src/types.rs
@@ -1904,10 +1904,9 @@ impl InvalidAtomicOrdering {
         if let ExprKind::MethodCall(method_path, _, args, _) = &expr.kind
             && recognized_names.contains(&method_path.ident.name)
             && let Some(m_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id)
-            && let Some(impl_did) = cx.tcx.impl_of_assoc(m_def_id)
-            && let Some(adt) = cx.tcx.type_of(impl_did).instantiate_identity().ty_adt_def()
             // skip extension traits, only lint functions from the standard library
-            && cx.tcx.trait_id_of_impl(impl_did).is_none()
+            && let Some(impl_did) = cx.tcx.inherent_impl_of_assoc(m_def_id)
+            && let Some(adt) = cx.tcx.type_of(impl_did).instantiate_identity().ty_adt_def()
             && let parent = cx.tcx.parent(adt.did())
             && cx.tcx.is_diagnostic_item(sym::atomic_mod, parent)
             && ATOMIC_TYPES.contains(&cx.tcx.item_name(adt.did()))
diff --git a/compiler/rustc_lint_defs/Cargo.toml b/compiler/rustc_lint_defs/Cargo.toml
index 9ab350daf69..c8201d5ea8c 100644
--- a/compiler/rustc_lint_defs/Cargo.toml
+++ b/compiler/rustc_lint_defs/Cargo.toml
@@ -5,11 +5,10 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-rustc_abi = { path = "../rustc_abi" }
 rustc_ast = { path = "../rustc_ast" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_error_messages = { path = "../rustc_error_messages" }
-rustc_hir = { path = "../rustc_hir" }
+rustc_hir_id = { path = "../rustc_hir_id" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_span = { path = "../rustc_span" }
diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index bee80335f74..97aa1065967 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -2301,18 +2301,18 @@ declare_lint! {
 
 declare_lint! {
     /// The `inline_no_sanitize` lint detects incompatible use of
-    /// [`#[inline(always)]`][inline] and [`#[no_sanitize(...)]`][no_sanitize].
+    /// [`#[inline(always)]`][inline] and [`#[sanitize(xyz = "off")]`][sanitize].
     ///
     /// [inline]: https://doc.rust-lang.org/reference/attributes/codegen.html#the-inline-attribute
-    /// [no_sanitize]: https://doc.rust-lang.org/nightly/unstable-book/language-features/no-sanitize.html
+    /// [sanitize]: https://doc.rust-lang.org/nightly/unstable-book/language-features/no-sanitize.html
     ///
     /// ### Example
     ///
     /// ```rust
-    /// #![feature(no_sanitize)]
+    /// #![feature(sanitize)]
     ///
     /// #[inline(always)]
-    /// #[no_sanitize(address)]
+    /// #[sanitize(address = "off")]
     /// fn x() {}
     ///
     /// fn main() {
@@ -2325,11 +2325,11 @@ declare_lint! {
     /// ### Explanation
     ///
     /// The use of the [`#[inline(always)]`][inline] attribute prevents the
-    /// the [`#[no_sanitize(...)]`][no_sanitize] attribute from working.
+    /// the [`#[sanitize(xyz = "off")]`][sanitize] attribute from working.
     /// Consider temporarily removing `inline` attribute.
     pub INLINE_NO_SANITIZE,
     Warn,
-    "detects incompatible use of `#[inline(always)]` and `#[no_sanitize(...)]`",
+    r#"detects incompatible use of `#[inline(always)]` and `#[sanitize(... = "off")]`"#,
 }
 
 declare_lint! {
@@ -5105,3 +5105,36 @@ declare_lint! {
         report_in_deps: true,
     };
 }
+
+declare_lint! {
+    /// The `tail_call_track_caller` lint detects usage of `become` attempting to tail call
+    /// a function marked with `#[track_caller]`.
+    ///
+    /// ### Example
+    ///
+    /// ```rust
+    /// #![feature(explicit_tail_calls)]
+    /// #![expect(incomplete_features)]
+    ///
+    /// #[track_caller]
+    /// fn f() {}
+    ///
+    /// fn g() {
+    ///     become f();
+    /// }
+    ///
+    /// g();
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// Due to implementation details of tail calls and `#[track_caller]` attribute, calls to
+    /// functions marked with `#[track_caller]` cannot become tail calls. As such using `become`
+    /// is no different than a normal call (except for changes in drop order).
+    pub TAIL_CALL_TRACK_CALLER,
+    Warn,
+    "detects tail calls of functions marked with `#[track_caller]`",
+    @feature_gate = explicit_tail_calls;
+}
diff --git a/compiler/rustc_lint_defs/src/lib.rs b/compiler/rustc_lint_defs/src/lib.rs
index dc5ea3922f1..2e84233e5a5 100644
--- a/compiler/rustc_lint_defs/src/lib.rs
+++ b/compiler/rustc_lint_defs/src/lib.rs
@@ -1,16 +1,15 @@
-use rustc_abi::ExternAbi;
+use std::borrow::Cow;
+
 use rustc_ast::AttrId;
 use rustc_ast::attr::AttributeExt;
-use rustc_ast::node_id::NodeId;
-use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
+use rustc_data_structures::fx::FxIndexSet;
 use rustc_data_structures::stable_hasher::{
     HashStable, StableCompare, StableHasher, ToStableHashKey,
 };
-use rustc_error_messages::{DiagMessage, MultiSpan};
-use rustc_hir::def::Namespace;
-use rustc_hir::def_id::DefPathHash;
-use rustc_hir::{HashStableContext, HirId, ItemLocalId};
+use rustc_error_messages::{DiagArgValue, DiagMessage, IntoDiagArg, MultiSpan};
+use rustc_hir_id::{HashStableContext, HirId, ItemLocalId};
 use rustc_macros::{Decodable, Encodable, HashStable_Generic};
+use rustc_span::def_id::DefPathHash;
 pub use rustc_span::edition::Edition;
 use rustc_span::{Ident, MacroRulesNormalizedIdent, Span, Symbol, sym};
 use serde::{Deserialize, Serialize};
@@ -138,7 +137,7 @@ impl LintExpectationId {
     }
 }
 
-impl<HCX: rustc_hir::HashStableContext> HashStable<HCX> for LintExpectationId {
+impl<HCX: HashStableContext> HashStable<HCX> for LintExpectationId {
     #[inline]
     fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
         match self {
@@ -156,7 +155,7 @@ impl<HCX: rustc_hir::HashStableContext> HashStable<HCX> for LintExpectationId {
     }
 }
 
-impl<HCX: rustc_hir::HashStableContext> ToStableHashKey<HCX> for LintExpectationId {
+impl<HCX: HashStableContext> ToStableHashKey<HCX> for LintExpectationId {
     type KeyType = (DefPathHash, ItemLocalId, u16, u16);
 
     #[inline]
@@ -297,6 +296,12 @@ impl Level {
     }
 }
 
+impl IntoDiagArg for Level {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Str(Cow::Borrowed(self.to_cmd_flag()))
+    }
+}
+
 /// Specification of a single lint.
 #[derive(Copy, Clone, Debug)]
 pub struct Lint {
@@ -617,7 +622,7 @@ pub enum BuiltinLintDiag {
     AbsPathWithModule(Span),
     ProcMacroDeriveResolutionFallback {
         span: Span,
-        ns: Namespace,
+        ns_descr: &'static str,
         ident: Ident,
     },
     MacroExpandedMacroExportsAccessedByAbsolutePaths(Span),
@@ -641,12 +646,12 @@ pub enum BuiltinLintDiag {
         path: String,
         since_kind: DeprecatedSinceKind,
     },
-    MissingAbi(Span, ExternAbi),
     UnusedDocComment(Span),
     UnusedBuiltinAttribute {
         attr_name: Symbol,
         macro_name: String,
         invoc_span: Span,
+        attr_span: Span,
     },
     PatternsInFnsWithoutBody {
         span: Span,
@@ -663,14 +668,6 @@ pub enum BuiltinLintDiag {
         is_string: bool,
         suggestion: Span,
     },
-    HiddenUnicodeCodepoints {
-        label: String,
-        count: usize,
-        span_label: Span,
-        labels: Option<Vec<(char, Span)>>,
-        escape: bool,
-        spans: Vec<(char, Span)>,
-    },
     TrailingMacro(bool, Ident),
     BreakWithLabelAndLoop(Span),
     UnicodeTextFlow(Span, String),
@@ -795,68 +792,11 @@ pub enum BuiltinLintDiag {
         suggestions: Vec<String>,
         docs: Option<&'static str>,
     },
-    InnerAttributeUnstable {
-        is_macro: bool,
-    },
     OutOfScopeMacroCalls {
         span: Span,
         path: String,
         location: String,
     },
-    UnexpectedBuiltinCfg {
-        cfg: String,
-        cfg_name: Symbol,
-        controlled_by: &'static str,
-    },
-}
-
-/// Lints that are buffered up early on in the `Session` before the
-/// `LintLevels` is calculated.
-#[derive(Debug)]
-pub struct BufferedEarlyLint {
-    /// The span of code that we are linting on.
-    pub span: Option<MultiSpan>,
-
-    /// The `NodeId` of the AST node that generated the lint.
-    pub node_id: NodeId,
-
-    /// A lint Id that can be passed to
-    /// `rustc_lint::early::EarlyContextAndPass::check_id`.
-    pub lint_id: LintId,
-
-    /// Customization of the `Diag<'_>` for the lint.
-    pub diagnostic: BuiltinLintDiag,
-}
-
-#[derive(Default, Debug)]
-pub struct LintBuffer {
-    pub map: FxIndexMap<NodeId, Vec<BufferedEarlyLint>>,
-}
-
-impl LintBuffer {
-    pub fn add_early_lint(&mut self, early_lint: BufferedEarlyLint) {
-        self.map.entry(early_lint.node_id).or_default().push(early_lint);
-    }
-
-    pub fn take(&mut self, id: NodeId) -> Vec<BufferedEarlyLint> {
-        // FIXME(#120456) - is `swap_remove` correct?
-        self.map.swap_remove(&id).unwrap_or_default()
-    }
-
-    pub fn buffer_lint(
-        &mut self,
-        lint: &'static Lint,
-        node_id: NodeId,
-        span: impl Into<MultiSpan>,
-        diagnostic: BuiltinLintDiag,
-    ) {
-        self.add_early_lint(BufferedEarlyLint {
-            lint_id: LintId::of(lint),
-            node_id,
-            span: Some(span.into()),
-            diagnostic,
-        });
-    }
 }
 
 pub type RegisteredTools = FxIndexSet<Ident>;
diff --git a/compiler/rustc_llvm/build.rs b/compiler/rustc_llvm/build.rs
index 1394edcee6b..d01f79dcade 100644
--- a/compiler/rustc_llvm/build.rs
+++ b/compiler/rustc_llvm/build.rs
@@ -226,7 +226,6 @@ fn main() {
     rerun_if_changed_anything_in_dir(Path::new("llvm-wrapper"));
     cfg.file("llvm-wrapper/PassWrapper.cpp")
         .file("llvm-wrapper/RustWrapper.cpp")
-        .file("llvm-wrapper/ArchiveWrapper.cpp")
         .file("llvm-wrapper/CoverageMappingWrapper.cpp")
         .file("llvm-wrapper/SymbolWrapper.cpp")
         .file("llvm-wrapper/Linker.cpp")
diff --git a/compiler/rustc_llvm/llvm-wrapper/ArchiveWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/ArchiveWrapper.cpp
deleted file mode 100644
index feac6a5649c..00000000000
--- a/compiler/rustc_llvm/llvm-wrapper/ArchiveWrapper.cpp
+++ /dev/null
@@ -1,208 +0,0 @@
-#include "LLVMWrapper.h"
-
-#include "llvm/Object/Archive.h"
-#include "llvm/Object/ArchiveWriter.h"
-#include "llvm/Support/Path.h"
-
-using namespace llvm;
-using namespace llvm::object;
-
-struct RustArchiveMember {
-  const char *Filename;
-  const char *Name;
-  Archive::Child Child;
-
-  RustArchiveMember()
-      : Filename(nullptr), Name(nullptr), Child(nullptr, nullptr, nullptr) {}
-  ~RustArchiveMember() {}
-};
-
-struct RustArchiveIterator {
-  bool First;
-  Archive::child_iterator Cur;
-  Archive::child_iterator End;
-  std::unique_ptr<Error> Err;
-
-  RustArchiveIterator(Archive::child_iterator Cur, Archive::child_iterator End,
-                      std::unique_ptr<Error> Err)
-      : First(true), Cur(Cur), End(End), Err(std::move(Err)) {}
-};
-
-enum class LLVMRustArchiveKind {
-  GNU,
-  BSD,
-  DARWIN,
-  COFF,
-  AIX_BIG,
-};
-
-static Archive::Kind fromRust(LLVMRustArchiveKind Kind) {
-  switch (Kind) {
-  case LLVMRustArchiveKind::GNU:
-    return Archive::K_GNU;
-  case LLVMRustArchiveKind::BSD:
-    return Archive::K_BSD;
-  case LLVMRustArchiveKind::DARWIN:
-    return Archive::K_DARWIN;
-  case LLVMRustArchiveKind::COFF:
-    return Archive::K_COFF;
-  case LLVMRustArchiveKind::AIX_BIG:
-    return Archive::K_AIXBIG;
-  default:
-    report_fatal_error("Bad ArchiveKind.");
-  }
-}
-
-typedef OwningBinary<Archive> *LLVMRustArchiveRef;
-typedef RustArchiveMember *LLVMRustArchiveMemberRef;
-typedef Archive::Child *LLVMRustArchiveChildRef;
-typedef Archive::Child const *LLVMRustArchiveChildConstRef;
-typedef RustArchiveIterator *LLVMRustArchiveIteratorRef;
-
-extern "C" LLVMRustArchiveRef LLVMRustOpenArchive(char *Path) {
-  ErrorOr<std::unique_ptr<MemoryBuffer>> BufOr = MemoryBuffer::getFile(
-      Path, /*IsText*/ false, /*RequiresNullTerminator=*/false);
-  if (!BufOr) {
-    LLVMRustSetLastError(BufOr.getError().message().c_str());
-    return nullptr;
-  }
-
-  Expected<std::unique_ptr<Archive>> ArchiveOr =
-      Archive::create(BufOr.get()->getMemBufferRef());
-
-  if (!ArchiveOr) {
-    LLVMRustSetLastError(toString(ArchiveOr.takeError()).c_str());
-    return nullptr;
-  }
-
-  OwningBinary<Archive> *Ret = new OwningBinary<Archive>(
-      std::move(ArchiveOr.get()), std::move(BufOr.get()));
-
-  return Ret;
-}
-
-extern "C" void LLVMRustDestroyArchive(LLVMRustArchiveRef RustArchive) {
-  delete RustArchive;
-}
-
-extern "C" LLVMRustArchiveIteratorRef
-LLVMRustArchiveIteratorNew(LLVMRustArchiveRef RustArchive) {
-  Archive *Archive = RustArchive->getBinary();
-  std::unique_ptr<Error> Err = std::make_unique<Error>(Error::success());
-  auto Cur = Archive->child_begin(*Err);
-  if (*Err) {
-    LLVMRustSetLastError(toString(std::move(*Err)).c_str());
-    return nullptr;
-  }
-  auto End = Archive->child_end();
-  return new RustArchiveIterator(Cur, End, std::move(Err));
-}
-
-extern "C" LLVMRustArchiveChildConstRef
-LLVMRustArchiveIteratorNext(LLVMRustArchiveIteratorRef RAI) {
-  if (RAI->Cur == RAI->End)
-    return nullptr;
-
-  // Advancing the iterator validates the next child, and this can
-  // uncover an error. LLVM requires that we check all Errors,
-  // so we only advance the iterator if we actually need to fetch
-  // the next child.
-  // This means we must not advance the iterator in the *first* call,
-  // but instead advance it *before* fetching the child in all later calls.
-  if (!RAI->First) {
-    ++RAI->Cur;
-    if (*RAI->Err) {
-      LLVMRustSetLastError(toString(std::move(*RAI->Err)).c_str());
-      return nullptr;
-    }
-  } else {
-    RAI->First = false;
-  }
-
-  if (RAI->Cur == RAI->End)
-    return nullptr;
-
-  const Archive::Child &Child = *RAI->Cur.operator->();
-  Archive::Child *Ret = new Archive::Child(Child);
-
-  return Ret;
-}
-
-extern "C" void LLVMRustArchiveChildFree(LLVMRustArchiveChildRef Child) {
-  delete Child;
-}
-
-extern "C" void LLVMRustArchiveIteratorFree(LLVMRustArchiveIteratorRef RAI) {
-  delete RAI;
-}
-
-extern "C" const char *
-LLVMRustArchiveChildName(LLVMRustArchiveChildConstRef Child, size_t *Size) {
-  Expected<StringRef> NameOrErr = Child->getName();
-  if (!NameOrErr) {
-    // rustc_codegen_llvm currently doesn't use this error string, but it might
-    // be useful in the future, and in the meantime this tells LLVM that the
-    // error was not ignored and that it shouldn't abort the process.
-    LLVMRustSetLastError(toString(NameOrErr.takeError()).c_str());
-    return nullptr;
-  }
-  StringRef Name = NameOrErr.get();
-  *Size = Name.size();
-  return Name.data();
-}
-
-extern "C" LLVMRustArchiveMemberRef
-LLVMRustArchiveMemberNew(char *Filename, char *Name,
-                         LLVMRustArchiveChildRef Child) {
-  RustArchiveMember *Member = new RustArchiveMember;
-  Member->Filename = Filename;
-  Member->Name = Name;
-  if (Child)
-    Member->Child = *Child;
-  return Member;
-}
-
-extern "C" void LLVMRustArchiveMemberFree(LLVMRustArchiveMemberRef Member) {
-  delete Member;
-}
-
-extern "C" LLVMRustResult LLVMRustWriteArchive(
-    char *Dst, size_t NumMembers, const LLVMRustArchiveMemberRef *NewMembers,
-    bool WriteSymbtab, LLVMRustArchiveKind RustKind, bool isEC) {
-
-  std::vector<NewArchiveMember> Members;
-  auto Kind = fromRust(RustKind);
-
-  for (size_t I = 0; I < NumMembers; I++) {
-    auto Member = NewMembers[I];
-    assert(Member->Name);
-    if (Member->Filename) {
-      Expected<NewArchiveMember> MOrErr =
-          NewArchiveMember::getFile(Member->Filename, true);
-      if (!MOrErr) {
-        LLVMRustSetLastError(toString(MOrErr.takeError()).c_str());
-        return LLVMRustResult::Failure;
-      }
-      MOrErr->MemberName = sys::path::filename(MOrErr->MemberName);
-      Members.push_back(std::move(*MOrErr));
-    } else {
-      Expected<NewArchiveMember> MOrErr =
-          NewArchiveMember::getOldMember(Member->Child, true);
-      if (!MOrErr) {
-        LLVMRustSetLastError(toString(MOrErr.takeError()).c_str());
-        return LLVMRustResult::Failure;
-      }
-      Members.push_back(std::move(*MOrErr));
-    }
-  }
-
-  auto SymtabMode = WriteSymbtab ? SymtabWritingMode::NormalSymtab
-                                 : SymtabWritingMode::NoSymtab;
-  auto Result =
-      writeArchive(Dst, Members, SymtabMode, Kind, true, false, nullptr, isEC);
-  if (!Result)
-    return LLVMRustResult::Success;
-  LLVMRustSetLastError(toString(std::move(Result)).c_str());
-
-  return LLVMRustResult::Failure;
-}
diff --git a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
index 588d867bbbf..361a5f76551 100644
--- a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
@@ -242,7 +242,7 @@ enum class LLVMRustAttributeKind {
   MinSize = 4,
   Naked = 5,
   NoAlias = 6,
-  NoCapture = 7,
+  CapturesAddress = 7,
   NoInline = 8,
   NonNull = 9,
   NoRedZone = 10,
@@ -277,6 +277,8 @@ enum class LLVMRustAttributeKind {
   FnRetThunkExtern = 41,
   Writable = 42,
   DeadOnUnwind = 43,
+  DeadOnReturn = 44,
+  CapturesReadOnly = 45,
 };
 
 static Attribute::AttrKind fromRust(LLVMRustAttributeKind Kind) {
@@ -295,12 +297,6 @@ static Attribute::AttrKind fromRust(LLVMRustAttributeKind Kind) {
     return Attribute::Naked;
   case LLVMRustAttributeKind::NoAlias:
     return Attribute::NoAlias;
-  case LLVMRustAttributeKind::NoCapture:
-#if LLVM_VERSION_GE(21, 0)
-    report_fatal_error("NoCapture doesn't exist in LLVM 21");
-#else
-    return Attribute::NoCapture;
-#endif
   case LLVMRustAttributeKind::NoCfCheck:
     return Attribute::NoCfCheck;
   case LLVMRustAttributeKind::NoInline:
@@ -369,6 +365,15 @@ static Attribute::AttrKind fromRust(LLVMRustAttributeKind Kind) {
     return Attribute::Writable;
   case LLVMRustAttributeKind::DeadOnUnwind:
     return Attribute::DeadOnUnwind;
+  case LLVMRustAttributeKind::DeadOnReturn:
+#if LLVM_VERSION_GE(21, 0)
+    return Attribute::DeadOnReturn;
+#else
+    report_fatal_error("DeadOnReturn attribute requires LLVM 21 or later");
+#endif
+  case LLVMRustAttributeKind::CapturesAddress:
+  case LLVMRustAttributeKind::CapturesReadOnly:
+    report_fatal_error("Should be handled separately");
   }
   report_fatal_error("bad LLVMRustAttributeKind");
 }
@@ -419,9 +424,14 @@ extern "C" void LLVMRustEraseInstFromParent(LLVMValueRef Instr) {
 extern "C" LLVMAttributeRef
 LLVMRustCreateAttrNoValue(LLVMContextRef C, LLVMRustAttributeKind RustAttr) {
 #if LLVM_VERSION_GE(21, 0)
-  // LLVM 21 replaced the NoCapture attribute with Captures(none).
-  if (RustAttr == LLVMRustAttributeKind::NoCapture) {
-    return wrap(Attribute::getWithCaptureInfo(*unwrap(C), CaptureInfo::none()));
+  if (RustAttr == LLVMRustAttributeKind::CapturesAddress) {
+    return wrap(Attribute::getWithCaptureInfo(
+        *unwrap(C), CaptureInfo(CaptureComponents::Address)));
+  }
+  if (RustAttr == LLVMRustAttributeKind::CapturesReadOnly) {
+    return wrap(Attribute::getWithCaptureInfo(
+        *unwrap(C), CaptureInfo(CaptureComponents::Address |
+                                CaptureComponents::ReadProvenance)));
   }
 #endif
   return wrap(Attribute::get(*unwrap(C), fromRust(RustAttr)));
@@ -473,6 +483,9 @@ extern "C" LLVMAttributeRef
 LLVMRustCreateRangeAttribute(LLVMContextRef C, unsigned NumBits,
                              const uint64_t LowerWords[],
                              const uint64_t UpperWords[]) {
+  // FIXME(Zalathar): There appears to be no stable guarantee that C++
+  // `AttrKind` values correspond directly to the `unsigned KindID` values
+  // accepted by LLVM-C API functions, though in practice they currently do.
   return LLVMCreateConstantRangeAttribute(C, Attribute::Range, NumBits,
                                           LowerWords, UpperWords);
 }
@@ -1453,60 +1466,6 @@ LLVMRustGetDiagInfoKind(LLVMDiagnosticInfoRef DI) {
   return toRust((DiagnosticKind)unwrap(DI)->getKind());
 }
 
-// This is kept distinct from LLVMGetTypeKind, because when
-// a new type kind is added, the Rust-side enum must be
-// updated or UB will result.
-extern "C" LLVMTypeKind LLVMRustGetTypeKind(LLVMTypeRef Ty) {
-  switch (unwrap(Ty)->getTypeID()) {
-  case Type::VoidTyID:
-    return LLVMVoidTypeKind;
-  case Type::HalfTyID:
-    return LLVMHalfTypeKind;
-  case Type::FloatTyID:
-    return LLVMFloatTypeKind;
-  case Type::DoubleTyID:
-    return LLVMDoubleTypeKind;
-  case Type::X86_FP80TyID:
-    return LLVMX86_FP80TypeKind;
-  case Type::FP128TyID:
-    return LLVMFP128TypeKind;
-  case Type::PPC_FP128TyID:
-    return LLVMPPC_FP128TypeKind;
-  case Type::LabelTyID:
-    return LLVMLabelTypeKind;
-  case Type::MetadataTyID:
-    return LLVMMetadataTypeKind;
-  case Type::IntegerTyID:
-    return LLVMIntegerTypeKind;
-  case Type::FunctionTyID:
-    return LLVMFunctionTypeKind;
-  case Type::StructTyID:
-    return LLVMStructTypeKind;
-  case Type::ArrayTyID:
-    return LLVMArrayTypeKind;
-  case Type::PointerTyID:
-    return LLVMPointerTypeKind;
-  case Type::FixedVectorTyID:
-    return LLVMVectorTypeKind;
-  case Type::TokenTyID:
-    return LLVMTokenTypeKind;
-  case Type::ScalableVectorTyID:
-    return LLVMScalableVectorTypeKind;
-  case Type::BFloatTyID:
-    return LLVMBFloatTypeKind;
-  case Type::X86_AMXTyID:
-    return LLVMX86_AMXTypeKind;
-  default: {
-    std::string error;
-    auto stream = llvm::raw_string_ostream(error);
-    stream << "Rust does not support the TypeID: " << unwrap(Ty)->getTypeID()
-           << " for the type: " << *unwrap(Ty);
-    stream.flush();
-    report_fatal_error(error.c_str());
-  }
-  }
-}
-
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(SMDiagnostic, LLVMSMDiagnosticRef)
 
 extern "C" LLVMSMDiagnosticRef LLVMRustGetSMDiagnostic(LLVMDiagnosticInfoRef DI,
@@ -1986,29 +1945,3 @@ extern "C" void LLVMRustSetNoSanitizeHWAddress(LLVMValueRef Global) {
   MD.NoHWAddress = true;
   GV.setSanitizerMetadata(MD);
 }
-
-enum class LLVMRustTailCallKind {
-  None = 0,
-  Tail = 1,
-  MustTail = 2,
-  NoTail = 3
-};
-
-extern "C" void LLVMRustSetTailCallKind(LLVMValueRef Call,
-                                        LLVMRustTailCallKind Kind) {
-  CallInst *CI = unwrap<CallInst>(Call);
-  switch (Kind) {
-  case LLVMRustTailCallKind::None:
-    CI->setTailCallKind(CallInst::TCK_None);
-    break;
-  case LLVMRustTailCallKind::Tail:
-    CI->setTailCallKind(CallInst::TCK_Tail);
-    break;
-  case LLVMRustTailCallKind::MustTail:
-    CI->setTailCallKind(CallInst::TCK_MustTail);
-    break;
-  case LLVMRustTailCallKind::NoTail:
-    CI->setTailCallKind(CallInst::TCK_NoTail);
-    break;
-  }
-}
diff --git a/compiler/rustc_log/Cargo.toml b/compiler/rustc_log/Cargo.toml
index c673d51a1d4..e9d7b4723f8 100644
--- a/compiler/rustc_log/Cargo.toml
+++ b/compiler/rustc_log/Cargo.toml
@@ -5,10 +5,10 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-tracing = "0.1.28"
 tracing-core = "=0.1.30" # FIXME(Nilstrieb) tracing has a deadlock: https://github.com/tokio-rs/tracing/issues/2635
 tracing-subscriber = { version = "0.3.3", default-features = false, features = ["fmt", "env-filter", "smallvec", "parking_lot", "ansi"] }
 tracing-tree = "0.3.1"
+tracing.workspace = true
 # tidy-alphabetical-end
 
 [features]
diff --git a/compiler/rustc_macros/src/diagnostics/utils.rs b/compiler/rustc_macros/src/diagnostics/utils.rs
index 060799e981d..c310b99d535 100644
--- a/compiler/rustc_macros/src/diagnostics/utils.rs
+++ b/compiler/rustc_macros/src/diagnostics/utils.rs
@@ -146,7 +146,7 @@ impl<'ty> FieldInnerTy<'ty> {
             };
 
             let path = &ty_path.path;
-            let ty = path.segments.iter().last().unwrap();
+            let ty = path.segments.last().unwrap();
             let syn::PathArguments::AngleBracketed(bracketed) = &ty.arguments else {
                 panic!("expected bracketed generic arguments");
             };
diff --git a/compiler/rustc_macros/src/print_attribute.rs b/compiler/rustc_macros/src/print_attribute.rs
index 9023520c750..0114e0dfde0 100644
--- a/compiler/rustc_macros/src/print_attribute.rs
+++ b/compiler/rustc_macros/src/print_attribute.rs
@@ -4,7 +4,7 @@ use syn::spanned::Spanned;
 use syn::{Data, Fields, Ident};
 use synstructure::Structure;
 
-fn print_fields(name: &Ident, fields: &Fields) -> (TokenStream, TokenStream, TokenStream) {
+fn print_fields(name: &Ident, fields: &Fields) -> (TokenStream, TokenStream) {
     let string_name = name.to_string();
     let mut disps = vec![quote! {let mut __printed_anything = false;}];
 
@@ -43,7 +43,6 @@ fn print_fields(name: &Ident, fields: &Fields) -> (TokenStream, TokenStream, Tok
                     #(#disps)*
                     __p.word("}");
                 },
-                quote! { true },
             )
         }
         Fields::Unnamed(fields_unnamed) => {
@@ -76,10 +75,9 @@ fn print_fields(name: &Ident, fields: &Fields) -> (TokenStream, TokenStream, Tok
                     #(#disps)*
                     __p.pclose();
                 },
-                quote! { true },
             )
         }
-        Fields::Unit => (quote! {}, quote! { __p.word(#string_name) }, quote! { true }),
+        Fields::Unit => (quote! {}, quote! { __p.word(#string_name) }),
     }
 }
 
@@ -89,51 +87,33 @@ pub(crate) fn print_attribute(input: Structure<'_>) -> TokenStream {
     };
 
     // Must be applied to an enum type.
-    let (code, printed) = match &input.ast().data {
+    let code = match &input.ast().data {
         Data::Enum(e) => {
-            let (arms, printed) = e
+            let arms = e
                 .variants
                 .iter()
                 .map(|x| {
                     let ident = &x.ident;
-                    let (pat, code, printed) = print_fields(ident, &x.fields);
+                    let (pat, code) = print_fields(ident, &x.fields);
 
-                    (
-                        quote! {
-                            Self::#ident #pat => {#code}
-                        },
-                        quote! {
-                            Self::#ident #pat => {#printed}
-                        },
-                    )
+                    quote! {
+                        Self::#ident #pat => {#code}
+                    }
                 })
-                .unzip::<_, _, Vec<_>, Vec<_>>();
+                .collect::<Vec<_>>();
 
-            (
-                quote! {
-                    match self {
-                        #(#arms)*
-                    }
-                },
-                quote! {
-                    match self {
-                        #(#printed)*
-                    }
-                },
-            )
+            quote! {
+                match self {
+                    #(#arms)*
+                }
+            }
         }
         Data::Struct(s) => {
-            let (pat, code, printed) = print_fields(&input.ast().ident, &s.fields);
-            (
-                quote! {
-                    let Self #pat = self;
-                    #code
-                },
-                quote! {
-                    let Self #pat = self;
-                    #printed
-                },
-            )
+            let (pat, code) = print_fields(&input.ast().ident, &s.fields);
+            quote! {
+                let Self #pat = self;
+                #code
+            }
         }
         Data::Union(u) => {
             return span_error(u.union_token.span(), "can't derive PrintAttribute on unions");
@@ -144,7 +124,7 @@ pub(crate) fn print_attribute(input: Structure<'_>) -> TokenStream {
     input.gen_impl(quote! {
         #[allow(unused)]
         gen impl PrintAttribute for @Self {
-            fn should_render(&self) -> bool { #printed }
+            fn should_render(&self) -> bool { true }
             fn print_attribute(&self, __p: &mut rustc_ast_pretty::pp::Printer) { #code }
         }
     })
diff --git a/compiler/rustc_metadata/Cargo.toml b/compiler/rustc_metadata/Cargo.toml
index 1b40d9f684e..4bb9e49ccce 100644
--- a/compiler/rustc_metadata/Cargo.toml
+++ b/compiler/rustc_metadata/Cargo.toml
@@ -5,7 +5,7 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-bitflags = "2.4.1"
+bitflags.workspace = true
 libloading = "0.8.0"
 odht = { version = "0.3.1", features = ["nightly"] }
 rustc_abi = { path = "../rustc_abi" }
@@ -31,7 +31,7 @@ rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 tempfile = "3.7.1"
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
 
 [target.'cfg(target_os = "aix")'.dependencies]
diff --git a/compiler/rustc_metadata/messages.ftl b/compiler/rustc_metadata/messages.ftl
index 4d3e879a098..e104be2c466 100644
--- a/compiler/rustc_metadata/messages.ftl
+++ b/compiler/rustc_metadata/messages.ftl
@@ -1,6 +1,3 @@
-metadata_as_needed_compatibility =
-    linking modifier `as-needed` is only compatible with `dylib` and `framework` linking kinds
-
 metadata_async_drop_types_in_dependency =
     found async drop types in dependency `{$extern_crate}`, but async_drop feature is disabled for `{$local_crate}`
     .help = if async drop type will be dropped in a crate without `feature(async_drop)`, sync Drop will be used
@@ -11,9 +8,6 @@ metadata_bad_panic_strategy =
 metadata_binary_output_to_tty =
     option `-o` or `--emit` is used to write binary output type `metadata` to stdout, but stdout is a tty
 
-metadata_bundle_needs_static =
-    linking modifier `bundle` is only compatible with `static` linking kind
-
 metadata_cannot_find_crate =
     can't find crate for `{$crate_name}`{$add_info}
 
@@ -60,10 +54,6 @@ metadata_crate_not_panic_runtime =
 metadata_dl_error =
     {$path}{$err}
 
-metadata_empty_link_name =
-    link name must not be empty
-    .label = empty link name
-
 metadata_empty_renaming_target =
     an empty renaming target was specified for library `{$lib_name}`
 
@@ -108,15 +98,6 @@ metadata_full_metadata_not_found =
 metadata_global_alloc_required =
     no global memory allocator found but one is required; link to std or add `#[global_allocator]` to a static item that implements the GlobalAlloc trait
 
-metadata_import_name_type_form =
-    import name type must be of the form `import_name_type = "string"`
-
-metadata_import_name_type_raw =
-    import name type can only be used with link kind `raw-dylib`
-
-metadata_import_name_type_x86 =
-    import name type is only supported on x86
-
 metadata_incompatible_panic_in_drop_strategy =
     the crate `{$crate_name}` is compiled with the panic-in-drop strategy `{$found_strategy}` which is incompatible with this crate's strategy of `{$desired_strategy}`
 
@@ -143,15 +124,10 @@ metadata_incompatible_target_modifiers_r_missed =
     mixing `{$flag_name_prefixed}` will cause an ABI mismatch in crate `{$local_crate}`
     .note = `{$flag_name_prefixed}={$local_value}` in this crate is incompatible with unset `{$flag_name_prefixed}` in dependency `{$extern_crate}`
     .help = the `{$flag_name_prefixed}` flag modifies the ABI so Rust crates compiled with different values of this flag cannot be used together safely
-metadata_incompatible_wasm_link =
-    `wasm_import_module` is incompatible with other arguments in `#[link]` attributes
 
 metadata_install_missing_components =
     maybe you need to install the missing components with: `rustup component add rust-src rustc-dev llvm-tools-preview`
 
-metadata_invalid_link_modifier =
-    invalid linking modifier syntax, expected '+' or '-' prefix before one of: bundle, verbatim, whole-archive, as-needed
-
 metadata_invalid_meta_files =
     found invalid metadata files for crate `{$crate_name}`{$add_info}
 
@@ -164,67 +140,18 @@ metadata_lib_framework_apple =
 metadata_lib_required =
     crate `{$crate_name}` required to be available in {$kind} format, but was not found in this form
 
-metadata_link_arg_unstable =
-    link kind `link-arg` is unstable
-
-metadata_link_cfg_form =
-    link cfg must be of the form `cfg(/* predicate */)`
-
-metadata_link_cfg_single_predicate =
-    link cfg must have a single predicate argument
-
-metadata_link_cfg_unstable =
-    link cfg is unstable
-
-metadata_link_framework_apple =
-    link kind `framework` is only supported on Apple targets
-
-metadata_link_kind_form =
-    link kind must be of the form `kind = "string"`
-
-metadata_link_modifiers_form =
-    link modifiers must be of the form `modifiers = "string"`
-
-metadata_link_name_form =
-    link name must be of the form `name = "string"`
-
 metadata_link_ordinal_raw_dylib =
     `#[link_ordinal]` is only supported if link kind is `raw-dylib`
 
-metadata_link_requires_name =
-    `#[link]` attribute requires a `name = "string"` argument
-    .label = missing `name` argument
-
 metadata_missing_native_library =
     could not find native static library `{$libname}`, perhaps an -L flag is missing?
 
 metadata_multiple_candidates =
     multiple candidates for `{$flavor}` dependency `{$crate_name}` found
 
-metadata_multiple_cfgs =
-    multiple `cfg` arguments in a single `#[link]` attribute
-
-metadata_multiple_import_name_type =
-    multiple `import_name_type` arguments in a single `#[link]` attribute
-
-metadata_multiple_kinds_in_link =
-    multiple `kind` arguments in a single `#[link]` attribute
-
-metadata_multiple_link_modifiers =
-    multiple `modifiers` arguments in a single `#[link]` attribute
-
-metadata_multiple_modifiers =
-    multiple `{$modifier}` modifiers in a single `modifiers` argument
-
-metadata_multiple_names_in_link =
-    multiple `name` arguments in a single `#[link]` attribute
-
 metadata_multiple_renamings =
     multiple renamings were specified for library `{$lib_name}`
 
-metadata_multiple_wasm_import =
-    multiple `wasm_import_module` arguments in a single `#[link]` attribute
-
 metadata_newer_crate_version =
     found possibly newer version of crate `{$crate_name}`{$add_info}
     .note = perhaps that crate needs to be recompiled?
@@ -263,15 +190,6 @@ metadata_prev_alloc_error_handler =
 metadata_prev_global_alloc =
     previous global allocator defined here
 
-metadata_raw_dylib_elf_unstable =
-    link kind `raw-dylib` is unstable on ELF platforms
-
-metadata_raw_dylib_no_nul =
-    link name must not contain NUL characters if link kind is `raw-dylib`
-
-metadata_raw_dylib_only_windows =
-    link kind `raw-dylib` is only supported on Windows targets
-
 metadata_raw_dylib_unsupported_abi =
     ABI not supported by `#[link(kind = "raw-dylib")]` on this architecture
 
@@ -307,19 +225,6 @@ metadata_target_not_installed =
 metadata_two_panic_runtimes =
     cannot link together two panic runtimes: {$prev_name} and {$cur_name}
 
-metadata_unexpected_link_arg =
-    unexpected `#[link]` argument, expected one of: name, kind, modifiers, cfg, wasm_import_module, import_name_type
-
-metadata_unknown_import_name_type =
-    unknown import name type `{$import_name_type}`, expected one of: decorated, noprefix, undecorated
-
-metadata_unknown_link_kind =
-    unknown link kind `{$kind}`, expected one of: static, dylib, framework, raw-dylib, link-arg
-    .label = unknown link kind
-
-metadata_unknown_link_modifier =
-    unknown linking modifier `{$modifier}`, expected one of: bundle, verbatim, whole-archive, as-needed
-
 metadata_unknown_target_modifier_unsafe_allowed = unknown target modifier `{$flag_name}`, requested by `-Cunsafe-allow-abi-mismatch={$flag_name}`
 
 metadata_wasm_c_abi =
diff --git a/compiler/rustc_metadata/src/creader.rs b/compiler/rustc_metadata/src/creader.rs
index 6bfb3769f24..5d776ea581d 100644
--- a/compiler/rustc_metadata/src/creader.rs
+++ b/compiler/rustc_metadata/src/creader.rs
@@ -32,6 +32,7 @@ use rustc_session::cstore::{CrateDepKind, CrateSource, ExternCrate, ExternCrateS
 use rustc_session::lint::{self, BuiltinLintDiag};
 use rustc_session::output::validate_crate_name;
 use rustc_session::search_paths::PathKind;
+use rustc_span::def_id::DefId;
 use rustc_span::edition::Edition;
 use rustc_span::{DUMMY_SP, Ident, Span, Symbol, sym};
 use rustc_target::spec::{PanicStrategy, Target};
@@ -275,6 +276,10 @@ impl CStore {
             .filter_map(|(cnum, data)| data.as_deref().map(|data| (cnum, data)))
     }
 
+    pub fn all_proc_macro_def_ids(&self) -> impl Iterator<Item = DefId> {
+        self.iter_crate_data().flat_map(|(krate, data)| data.proc_macros_for_crate(krate, self))
+    }
+
     fn push_dependencies_in_postorder(&self, deps: &mut IndexSet<CrateNum>, cnum: CrateNum) {
         if !deps.contains(&cnum) {
             let data = self.get_crate_data(cnum);
diff --git a/compiler/rustc_metadata/src/errors.rs b/compiler/rustc_metadata/src/errors.rs
index 0332dba1077..e5a4fd48353 100644
--- a/compiler/rustc_metadata/src/errors.rs
+++ b/compiler/rustc_metadata/src/errors.rs
@@ -84,187 +84,6 @@ pub struct IncompatiblePanicInDropStrategy {
 }
 
 #[derive(Diagnostic)]
-#[diag(metadata_multiple_names_in_link)]
-pub struct MultipleNamesInLink {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_multiple_kinds_in_link)]
-pub struct MultipleKindsInLink {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_link_name_form)]
-pub struct LinkNameForm {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_link_kind_form)]
-pub struct LinkKindForm {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_link_modifiers_form)]
-pub struct LinkModifiersForm {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_link_cfg_form)]
-pub struct LinkCfgForm {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_wasm_import_form)]
-pub struct WasmImportForm {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_empty_link_name, code = E0454)]
-pub struct EmptyLinkName {
-    #[primary_span]
-    #[label]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_link_framework_apple, code = E0455)]
-pub struct LinkFrameworkApple {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_raw_dylib_only_windows, code = E0455)]
-pub struct RawDylibOnlyWindows {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_unknown_link_kind, code = E0458)]
-pub struct UnknownLinkKind<'a> {
-    #[primary_span]
-    #[label]
-    pub span: Span,
-    pub kind: &'a str,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_multiple_link_modifiers)]
-pub struct MultipleLinkModifiers {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_multiple_cfgs)]
-pub struct MultipleCfgs {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_link_cfg_single_predicate)]
-pub struct LinkCfgSinglePredicate {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_multiple_wasm_import)]
-pub struct MultipleWasmImport {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_unexpected_link_arg)]
-pub struct UnexpectedLinkArg {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_invalid_link_modifier)]
-pub struct InvalidLinkModifier {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_multiple_modifiers)]
-pub struct MultipleModifiers<'a> {
-    #[primary_span]
-    pub span: Span,
-    pub modifier: &'a str,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_bundle_needs_static)]
-pub struct BundleNeedsStatic {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_whole_archive_needs_static)]
-pub struct WholeArchiveNeedsStatic {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_as_needed_compatibility)]
-pub struct AsNeededCompatibility {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_unknown_link_modifier)]
-pub struct UnknownLinkModifier<'a> {
-    #[primary_span]
-    pub span: Span,
-    pub modifier: &'a str,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_incompatible_wasm_link)]
-pub struct IncompatibleWasmLink {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_link_requires_name, code = E0459)]
-pub struct LinkRequiresName {
-    #[primary_span]
-    #[label]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_raw_dylib_no_nul)]
-pub struct RawDylibNoNul {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
 #[diag(metadata_link_ordinal_raw_dylib)]
 pub struct LinkOrdinalRawDylib {
     #[primary_span]
@@ -707,42 +526,6 @@ pub struct LibFilenameForm<'a> {
 }
 
 #[derive(Diagnostic)]
-#[diag(metadata_multiple_import_name_type)]
-pub struct MultipleImportNameType {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_import_name_type_form)]
-pub struct ImportNameTypeForm {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_import_name_type_x86)]
-pub struct ImportNameTypeX86 {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_unknown_import_name_type)]
-pub struct UnknownImportNameType<'a> {
-    #[primary_span]
-    pub span: Span,
-    pub import_name_type: &'a str,
-}
-
-#[derive(Diagnostic)]
-#[diag(metadata_import_name_type_raw)]
-pub struct ImportNameTypeRaw {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
 #[diag(metadata_wasm_c_abi)]
 pub(crate) struct WasmCAbi {
     #[primary_span]
diff --git a/compiler/rustc_metadata/src/native_libs.rs b/compiler/rustc_metadata/src/native_libs.rs
index 958e314efab..82738c68c59 100644
--- a/compiler/rustc_metadata/src/native_libs.rs
+++ b/compiler/rustc_metadata/src/native_libs.rs
@@ -3,25 +3,21 @@ use std::path::{Path, PathBuf};
 
 use rustc_abi::ExternAbi;
 use rustc_ast::CRATE_NODE_ID;
-use rustc_attr_parsing as attr;
+use rustc_attr_parsing::{ShouldEmit, eval_config_entry};
 use rustc_data_structures::fx::FxHashSet;
-use rustc_hir::attrs::AttributeKind;
+use rustc_hir::attrs::{AttributeKind, NativeLibKind, PeImportNameType};
 use rustc_hir::find_attr;
 use rustc_middle::query::LocalCrate;
 use rustc_middle::ty::{self, List, Ty, TyCtxt};
 use rustc_session::Session;
 use rustc_session::config::CrateType;
-use rustc_session::cstore::{
-    DllCallingConvention, DllImport, ForeignModule, NativeLib, PeImportNameType,
-};
-use rustc_session::parse::feature_err;
+use rustc_session::cstore::{DllCallingConvention, DllImport, ForeignModule, NativeLib};
 use rustc_session::search_paths::PathKind;
-use rustc_session::utils::NativeLibKind;
+use rustc_span::Symbol;
 use rustc_span::def_id::{DefId, LOCAL_CRATE};
-use rustc_span::{Symbol, sym};
 use rustc_target::spec::{BinaryFormat, LinkSelfContainedComponents};
 
-use crate::{errors, fluent_generated};
+use crate::errors;
 
 /// The fallback directories are passed to linker, but not used when rustc does the search,
 /// because in the latter case the set of fallback directories cannot always be determined
@@ -192,7 +188,9 @@ pub(crate) fn collect(tcx: TyCtxt<'_>, LocalCrate: LocalCrate) -> Vec<NativeLib>
 
 pub(crate) fn relevant_lib(sess: &Session, lib: &NativeLib) -> bool {
     match lib.cfg {
-        Some(ref cfg) => attr::cfg_matches(cfg, sess, CRATE_NODE_ID, None),
+        Some(ref cfg) => {
+            eval_config_entry(sess, cfg, CRATE_NODE_ID, None, ShouldEmit::ErrorsAndLints).as_bool()
+        }
         None => true,
     }
 }
@@ -213,289 +211,23 @@ impl<'tcx> Collector<'tcx> {
             return;
         }
 
-        // Process all of the #[link(..)]-style arguments
-        let features = self.tcx.features();
-
-        for m in self.tcx.get_attrs(def_id, sym::link) {
-            let Some(items) = m.meta_item_list() else {
-                continue;
-            };
-
-            let mut name = None;
-            let mut kind = None;
-            let mut modifiers = None;
-            let mut cfg = None;
-            let mut wasm_import_module = None;
-            let mut import_name_type = None;
-            for item in items.iter() {
-                match item.name() {
-                    Some(sym::name) => {
-                        if name.is_some() {
-                            sess.dcx().emit_err(errors::MultipleNamesInLink { span: item.span() });
-                            continue;
-                        }
-                        let Some(link_name) = item.value_str() else {
-                            sess.dcx().emit_err(errors::LinkNameForm { span: item.span() });
-                            continue;
-                        };
-                        let span = item.name_value_literal_span().unwrap();
-                        if link_name.is_empty() {
-                            sess.dcx().emit_err(errors::EmptyLinkName { span });
-                        }
-                        name = Some((link_name, span));
-                    }
-                    Some(sym::kind) => {
-                        if kind.is_some() {
-                            sess.dcx().emit_err(errors::MultipleKindsInLink { span: item.span() });
-                            continue;
-                        }
-                        let Some(link_kind) = item.value_str() else {
-                            sess.dcx().emit_err(errors::LinkKindForm { span: item.span() });
-                            continue;
-                        };
-
-                        let span = item.name_value_literal_span().unwrap();
-                        let link_kind = match link_kind.as_str() {
-                            "static" => NativeLibKind::Static { bundle: None, whole_archive: None },
-                            "dylib" => NativeLibKind::Dylib { as_needed: None },
-                            "framework" => {
-                                if !sess.target.is_like_darwin {
-                                    sess.dcx().emit_err(errors::LinkFrameworkApple { span });
-                                }
-                                NativeLibKind::Framework { as_needed: None }
-                            }
-                            "raw-dylib" => {
-                                if sess.target.is_like_windows {
-                                    // raw-dylib is stable and working on Windows
-                                } else if sess.target.binary_format == BinaryFormat::Elf
-                                    && features.raw_dylib_elf()
-                                {
-                                    // raw-dylib is unstable on ELF, but the user opted in
-                                } else if sess.target.binary_format == BinaryFormat::Elf
-                                    && sess.is_nightly_build()
-                                {
-                                    feature_err(
-                                        sess,
-                                        sym::raw_dylib_elf,
-                                        span,
-                                        fluent_generated::metadata_raw_dylib_elf_unstable,
-                                    )
-                                    .emit();
-                                } else {
-                                    sess.dcx().emit_err(errors::RawDylibOnlyWindows { span });
-                                }
-
-                                NativeLibKind::RawDylib
-                            }
-                            "link-arg" => {
-                                if !features.link_arg_attribute() {
-                                    feature_err(
-                                        sess,
-                                        sym::link_arg_attribute,
-                                        span,
-                                        fluent_generated::metadata_link_arg_unstable,
-                                    )
-                                    .emit();
-                                }
-                                NativeLibKind::LinkArg
-                            }
-                            kind => {
-                                sess.dcx().emit_err(errors::UnknownLinkKind { span, kind });
-                                continue;
-                            }
-                        };
-                        kind = Some(link_kind);
-                    }
-                    Some(sym::modifiers) => {
-                        if modifiers.is_some() {
-                            sess.dcx()
-                                .emit_err(errors::MultipleLinkModifiers { span: item.span() });
-                            continue;
-                        }
-                        let Some(link_modifiers) = item.value_str() else {
-                            sess.dcx().emit_err(errors::LinkModifiersForm { span: item.span() });
-                            continue;
-                        };
-                        modifiers = Some((link_modifiers, item.name_value_literal_span().unwrap()));
-                    }
-                    Some(sym::cfg) => {
-                        if cfg.is_some() {
-                            sess.dcx().emit_err(errors::MultipleCfgs { span: item.span() });
-                            continue;
-                        }
-                        let Some(link_cfg) = item.meta_item_list() else {
-                            sess.dcx().emit_err(errors::LinkCfgForm { span: item.span() });
-                            continue;
-                        };
-                        let [link_cfg] = link_cfg else {
-                            sess.dcx()
-                                .emit_err(errors::LinkCfgSinglePredicate { span: item.span() });
-                            continue;
-                        };
-                        let Some(link_cfg) = link_cfg.meta_item_or_bool() else {
-                            sess.dcx()
-                                .emit_err(errors::LinkCfgSinglePredicate { span: item.span() });
-                            continue;
-                        };
-                        if !features.link_cfg() {
-                            feature_err(
-                                sess,
-                                sym::link_cfg,
-                                item.span(),
-                                fluent_generated::metadata_link_cfg_unstable,
-                            )
-                            .emit();
-                        }
-                        cfg = Some(link_cfg.clone());
-                    }
-                    Some(sym::wasm_import_module) => {
-                        if wasm_import_module.is_some() {
-                            sess.dcx().emit_err(errors::MultipleWasmImport { span: item.span() });
-                            continue;
-                        }
-                        let Some(link_wasm_import_module) = item.value_str() else {
-                            sess.dcx().emit_err(errors::WasmImportForm { span: item.span() });
-                            continue;
-                        };
-                        wasm_import_module = Some((link_wasm_import_module, item.span()));
-                    }
-                    Some(sym::import_name_type) => {
-                        if import_name_type.is_some() {
-                            sess.dcx()
-                                .emit_err(errors::MultipleImportNameType { span: item.span() });
-                            continue;
-                        }
-                        let Some(link_import_name_type) = item.value_str() else {
-                            sess.dcx().emit_err(errors::ImportNameTypeForm { span: item.span() });
-                            continue;
-                        };
-                        if self.tcx.sess.target.arch != "x86" {
-                            sess.dcx().emit_err(errors::ImportNameTypeX86 { span: item.span() });
-                            continue;
-                        }
-
-                        let link_import_name_type = match link_import_name_type.as_str() {
-                            "decorated" => PeImportNameType::Decorated,
-                            "noprefix" => PeImportNameType::NoPrefix,
-                            "undecorated" => PeImportNameType::Undecorated,
-                            import_name_type => {
-                                sess.dcx().emit_err(errors::UnknownImportNameType {
-                                    span: item.span(),
-                                    import_name_type,
-                                });
-                                continue;
-                            }
-                        };
-                        import_name_type = Some((link_import_name_type, item.span()));
-                    }
-                    _ => {
-                        sess.dcx().emit_err(errors::UnexpectedLinkArg { span: item.span() });
-                    }
-                }
-            }
-
-            // Do this outside the above loop so we don't depend on modifiers coming after kinds
-            let mut verbatim = None;
-            if let Some((modifiers, span)) = modifiers {
-                for modifier in modifiers.as_str().split(',') {
-                    let (modifier, value) = match modifier.strip_prefix(&['+', '-']) {
-                        Some(m) => (m, modifier.starts_with('+')),
-                        None => {
-                            sess.dcx().emit_err(errors::InvalidLinkModifier { span });
-                            continue;
-                        }
-                    };
-
-                    macro report_unstable_modifier($feature: ident) {
-                        if !features.$feature() {
-                            // FIXME: make this translatable
-                            #[expect(rustc::untranslatable_diagnostic)]
-                            feature_err(
-                                sess,
-                                sym::$feature,
-                                span,
-                                format!("linking modifier `{modifier}` is unstable"),
-                            )
-                            .emit();
-                        }
-                    }
-                    let assign_modifier = |dst: &mut Option<bool>| {
-                        if dst.is_some() {
-                            sess.dcx().emit_err(errors::MultipleModifiers { span, modifier });
-                        } else {
-                            *dst = Some(value);
-                        }
-                    };
-                    match (modifier, &mut kind) {
-                        ("bundle", Some(NativeLibKind::Static { bundle, .. })) => {
-                            assign_modifier(bundle)
-                        }
-                        ("bundle", _) => {
-                            sess.dcx().emit_err(errors::BundleNeedsStatic { span });
-                        }
-
-                        ("verbatim", _) => assign_modifier(&mut verbatim),
-
-                        ("whole-archive", Some(NativeLibKind::Static { whole_archive, .. })) => {
-                            assign_modifier(whole_archive)
-                        }
-                        ("whole-archive", _) => {
-                            sess.dcx().emit_err(errors::WholeArchiveNeedsStatic { span });
-                        }
-
-                        ("as-needed", Some(NativeLibKind::Dylib { as_needed }))
-                        | ("as-needed", Some(NativeLibKind::Framework { as_needed })) => {
-                            report_unstable_modifier!(native_link_modifiers_as_needed);
-                            assign_modifier(as_needed)
-                        }
-                        ("as-needed", _) => {
-                            sess.dcx().emit_err(errors::AsNeededCompatibility { span });
-                        }
-
-                        _ => {
-                            sess.dcx().emit_err(errors::UnknownLinkModifier { span, modifier });
-                        }
-                    }
-                }
-            }
-
-            if let Some((_, span)) = wasm_import_module {
-                if name.is_some() || kind.is_some() || modifiers.is_some() || cfg.is_some() {
-                    sess.dcx().emit_err(errors::IncompatibleWasmLink { span });
-                }
-            }
-
-            if wasm_import_module.is_some() {
-                (name, kind) = (wasm_import_module, Some(NativeLibKind::WasmImportModule));
-            }
-            let Some((name, name_span)) = name else {
-                sess.dcx().emit_err(errors::LinkRequiresName { span: m.span() });
-                continue;
-            };
-
-            // Do this outside of the loop so that `import_name_type` can be specified before `kind`.
-            if let Some((_, span)) = import_name_type {
-                if kind != Some(NativeLibKind::RawDylib) {
-                    sess.dcx().emit_err(errors::ImportNameTypeRaw { span });
-                }
-            }
-
-            let dll_imports = match kind {
-                Some(NativeLibKind::RawDylib) => {
-                    if name.as_str().contains('\0') {
-                        sess.dcx().emit_err(errors::RawDylibNoNul { span: name_span });
-                    }
-                    foreign_items
-                        .iter()
-                        .map(|&child_item| {
-                            self.build_dll_import(
-                                abi,
-                                import_name_type.map(|(import_name_type, _)| import_name_type),
-                                child_item,
-                            )
-                        })
-                        .collect()
-                }
+        for attr in
+            find_attr!(self.tcx.get_all_attrs(def_id), AttributeKind::Link(links, _) => links)
+                .iter()
+                .map(|v| v.iter())
+                .flatten()
+        {
+            let dll_imports = match attr.kind {
+                NativeLibKind::RawDylib => foreign_items
+                    .iter()
+                    .map(|&child_item| {
+                        self.build_dll_import(
+                            abi,
+                            attr.import_name_type.map(|(import_name_type, _)| import_name_type),
+                            child_item,
+                        )
+                    })
+                    .collect(),
                 _ => {
                     for &child_item in foreign_items {
                         if let Some(span) = find_attr!(self.tcx.get_all_attrs(child_item), AttributeKind::LinkOrdinal {span, ..} => *span)
@@ -508,15 +240,20 @@ impl<'tcx> Collector<'tcx> {
                 }
             };
 
-            let kind = kind.unwrap_or(NativeLibKind::Unspecified);
-            let filename = find_bundled_library(name, verbatim, kind, cfg.is_some(), self.tcx);
+            let filename = find_bundled_library(
+                attr.name,
+                attr.verbatim,
+                attr.kind,
+                attr.cfg.is_some(),
+                self.tcx,
+            );
             self.libs.push(NativeLib {
-                name,
+                name: attr.name,
                 filename,
-                kind,
-                cfg,
+                kind: attr.kind,
+                cfg: attr.cfg.clone(),
                 foreign_module: Some(def_id.to_def_id()),
-                verbatim,
+                verbatim: attr.verbatim,
                 dll_imports,
             });
         }
@@ -701,7 +438,7 @@ impl<'tcx> Collector<'tcx> {
             .link_ordinal
             .map_or(import_name_type, |ord| Some(PeImportNameType::Ordinal(ord)));
 
-        let name = codegen_fn_attrs.link_name.unwrap_or_else(|| self.tcx.item_name(item));
+        let name = codegen_fn_attrs.symbol_name.unwrap_or_else(|| self.tcx.item_name(item));
 
         if self.tcx.sess.target.binary_format == BinaryFormat::Elf {
             let name = name.as_str();
diff --git a/compiler/rustc_metadata/src/rmeta/decoder.rs b/compiler/rustc_metadata/src/rmeta/decoder.rs
index 548c56a97bc..110b26c62ef 100644
--- a/compiler/rustc_metadata/src/rmeta/decoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/decoder.rs
@@ -2014,6 +2014,22 @@ impl CrateMetadata {
         self.root.is_proc_macro_crate()
     }
 
+    pub(crate) fn proc_macros_for_crate(
+        &self,
+        krate: CrateNum,
+        cstore: &CStore,
+    ) -> impl Iterator<Item = DefId> {
+        gen move {
+            for def_id in self.root.proc_macro_data.as_ref().into_iter().flat_map(move |data| {
+                data.macros
+                    .decode(CrateMetadataRef { cdata: self, cstore })
+                    .map(move |index| DefId { index, krate })
+            }) {
+                yield def_id;
+            }
+        }
+    }
+
     pub(crate) fn name(&self) -> Symbol {
         self.root.header.name
     }
diff --git a/compiler/rustc_metadata/src/rmeta/encoder.rs b/compiler/rustc_metadata/src/rmeta/encoder.rs
index d42c8b947a4..a7e7e9985f4 100644
--- a/compiler/rustc_metadata/src/rmeta/encoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/encoder.rs
@@ -1981,7 +1981,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                 def_key.disambiguated_data.data = DefPathData::MacroNs(name);
 
                 let def_id = id.to_def_id();
-                self.tables.def_kind.set_some(def_id.index, DefKind::Macro(macro_kind));
+                self.tables.def_kind.set_some(def_id.index, DefKind::Macro(macro_kind.into()));
                 self.tables.proc_macro.set_some(def_id.index, macro_kind);
                 self.encode_attrs(id);
                 record!(self.tables.def_keys[def_id] <- def_key);
diff --git a/compiler/rustc_metadata/src/rmeta/mod.rs b/compiler/rustc_metadata/src/rmeta/mod.rs
index 99174e4ad2f..1f7d142d330 100644
--- a/compiler/rustc_metadata/src/rmeta/mod.rs
+++ b/compiler/rustc_metadata/src/rmeta/mod.rs
@@ -11,7 +11,7 @@ use rustc_abi::{FieldIdx, ReprOptions, VariantIdx};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::svh::Svh;
 use rustc_hir::attrs::StrippedCfgItem;
-use rustc_hir::def::{CtorKind, DefKind, DocLinkResMap};
+use rustc_hir::def::{CtorKind, DefKind, DocLinkResMap, MacroKinds};
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, DefIndex, DefPathHash, StableCrateId};
 use rustc_hir::definitions::DefKey;
 use rustc_hir::lang_items::LangItem;
diff --git a/compiler/rustc_metadata/src/rmeta/table.rs b/compiler/rustc_metadata/src/rmeta/table.rs
index 0671aa20399..2cb07a28a8a 100644
--- a/compiler/rustc_metadata/src/rmeta/table.rs
+++ b/compiler/rustc_metadata/src/rmeta/table.rs
@@ -81,7 +81,7 @@ impl FixedSizeEncoding for u64 {
 }
 
 macro_rules! fixed_size_enum {
-    ($ty:ty { $(($($pat:tt)*))* }) => {
+    ($ty:ty { $(($($pat:tt)*))* } $( unreachable { $(($($upat:tt)*))+ } )?) => {
         impl FixedSizeEncoding for Option<$ty> {
             type ByteArray = [u8;1];
 
@@ -103,12 +103,24 @@ macro_rules! fixed_size_enum {
                 b[0] = match self {
                     None => unreachable!(),
                     $(Some($($pat)*) => 1 + ${index()},)*
+                    $(Some($($($upat)*)|+) => unreachable!(),)?
                 }
             }
         }
     }
 }
 
+// Workaround; need const traits to construct bitflags in a const
+macro_rules! const_macro_kinds {
+    ($($name:ident),+$(,)?) => (MacroKinds::from_bits_truncate($(MacroKinds::$name.bits())|+))
+}
+const MACRO_KINDS_ATTR_BANG: MacroKinds = const_macro_kinds!(ATTR, BANG);
+const MACRO_KINDS_DERIVE_BANG: MacroKinds = const_macro_kinds!(DERIVE, BANG);
+const MACRO_KINDS_DERIVE_ATTR: MacroKinds = const_macro_kinds!(DERIVE, ATTR);
+const MACRO_KINDS_DERIVE_ATTR_BANG: MacroKinds = const_macro_kinds!(DERIVE, ATTR, BANG);
+// Ensure that we get a compilation error if MacroKinds gets extended without updating metadata.
+const _: () = assert!(MACRO_KINDS_DERIVE_ATTR_BANG.is_all());
+
 fixed_size_enum! {
     DefKind {
         ( Mod                                      )
@@ -151,10 +163,16 @@ fixed_size_enum! {
         ( Ctor(CtorOf::Struct, CtorKind::Const)    )
         ( Ctor(CtorOf::Variant, CtorKind::Fn)      )
         ( Ctor(CtorOf::Variant, CtorKind::Const)   )
-        ( Macro(MacroKind::Bang)                   )
-        ( Macro(MacroKind::Attr)                   )
-        ( Macro(MacroKind::Derive)                 )
+        ( Macro(MacroKinds::BANG)                  )
+        ( Macro(MacroKinds::ATTR)                  )
+        ( Macro(MacroKinds::DERIVE)                )
+        ( Macro(MACRO_KINDS_ATTR_BANG)             )
+        ( Macro(MACRO_KINDS_DERIVE_ATTR)           )
+        ( Macro(MACRO_KINDS_DERIVE_BANG)           )
+        ( Macro(MACRO_KINDS_DERIVE_ATTR_BANG)      )
         ( SyntheticCoroutineBody                   )
+    } unreachable {
+        ( Macro(_)                                 )
     }
 }
 
diff --git a/compiler/rustc_middle/Cargo.toml b/compiler/rustc_middle/Cargo.toml
index fbcce16cedc..782066981c9 100644
--- a/compiler/rustc_middle/Cargo.toml
+++ b/compiler/rustc_middle/Cargo.toml
@@ -5,7 +5,7 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-bitflags = "2.4.1"
+bitflags.workspace = true
 either = "1.5.0"
 gsgdt = "0.1.2"
 polonius-engine = "0.13.0"
@@ -34,8 +34,8 @@ rustc_target = { path = "../rustc_target" }
 rustc_thread_pool = { path = "../rustc_thread_pool" }
 rustc_type_ir = { path = "../rustc_type_ir" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec = "0.2.12"
-tracing = "0.1"
+thin-vec.workspace = true
+tracing.workspace = true
 # tidy-alphabetical-end
 
 [features]
diff --git a/compiler/rustc_middle/src/lib.rs b/compiler/rustc_middle/src/lib.rs
index e5cc23c213d..cf0549fa668 100644
--- a/compiler/rustc_middle/src/lib.rs
+++ b/compiler/rustc_middle/src/lib.rs
@@ -60,6 +60,7 @@
 #![feature(try_trait_v2_residual)]
 #![feature(try_trait_v2_yeet)]
 #![feature(type_alias_impl_trait)]
+#![feature(unwrap_infallible)]
 #![feature(yeet_expr)]
 #![recursion_limit = "256"]
 // tidy-alphabetical-end
diff --git a/compiler/rustc_middle/src/lint.rs b/compiler/rustc_middle/src/lint.rs
index 341a735f88f..f70b7b6fad7 100644
--- a/compiler/rustc_middle/src/lint.rs
+++ b/compiler/rustc_middle/src/lint.rs
@@ -211,11 +211,28 @@ impl LintExpectation {
 }
 
 fn explain_lint_level_source(
+    sess: &Session,
     lint: &'static Lint,
     level: Level,
     src: LintLevelSource,
     err: &mut Diag<'_, ()>,
 ) {
+    // Find the name of the lint group that contains the given lint.
+    // Assumes the lint only belongs to one group.
+    let lint_group_name = |lint| {
+        let lint_groups_iter = sess.lint_groups_iter();
+        let lint_id = LintId::of(lint);
+        lint_groups_iter
+            .filter(|lint_group| !lint_group.is_externally_loaded)
+            .find(|lint_group| {
+                lint_group
+                    .lints
+                    .iter()
+                    .find(|lint_group_lint| **lint_group_lint == lint_id)
+                    .is_some()
+            })
+            .map(|lint_group| lint_group.name)
+    };
     let name = lint.name_lower();
     if let Level::Allow = level {
         // Do not point at `#[allow(compat_lint)]` as the reason for a compatibility lint
@@ -224,7 +241,15 @@ fn explain_lint_level_source(
     }
     match src {
         LintLevelSource::Default => {
-            err.note_once(format!("`#[{}({})]` on by default", level.as_str(), name));
+            let level_str = level.as_str();
+            match lint_group_name(lint) {
+                Some(group_name) => {
+                    err.note_once(format!("`#[{level_str}({name})]` (part of `#[{level_str}({group_name})]`) on by default"));
+                }
+                None => {
+                    err.note_once(format!("`#[{level_str}({name})]` on by default"));
+                }
+            }
         }
         LintLevelSource::CommandLine(lint_flag_val, orig_level) => {
             let flag = orig_level.to_cmd_flag();
@@ -427,7 +452,7 @@ pub fn lint_level(
             decorate(&mut err);
         }
 
-        explain_lint_level_source(lint, level, src, &mut err);
+        explain_lint_level_source(sess, lint, level, src, &mut err);
         err.emit()
     }
     lint_level_impl(sess, lint, level, span, Box::new(decorate))
diff --git a/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs b/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
index 94384e64afd..866736f74a0 100644
--- a/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
+++ b/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
@@ -1,13 +1,11 @@
 use std::borrow::Cow;
 
 use rustc_abi::Align;
-use rustc_ast::expand::autodiff_attrs::AutoDiffAttrs;
-use rustc_hir::attrs::{InlineAttr, InstructionSetAttr, OptimizeAttr};
+use rustc_hir::attrs::{InlineAttr, InstructionSetAttr, Linkage, OptimizeAttr};
 use rustc_macros::{HashStable, TyDecodable, TyEncodable};
 use rustc_span::Symbol;
 use rustc_target::spec::SanitizerSet;
 
-use crate::mir::mono::Linkage;
 use crate::ty::{InstanceKind, TyCtxt};
 
 impl<'tcx> TyCtxt<'tcx> {
@@ -36,14 +34,10 @@ pub struct CodegenFnAttrs {
     pub inline: InlineAttr,
     /// Parsed representation of the `#[optimize]` attribute
     pub optimize: OptimizeAttr,
-    /// The `#[export_name = "..."]` attribute, indicating a custom symbol a
-    /// function should be exported under
-    pub export_name: Option<Symbol>,
-    /// The `#[link_name = "..."]` attribute, indicating a custom symbol an
-    /// imported function should be imported as. Note that `export_name`
-    /// probably isn't set when this is set, this is for foreign items while
-    /// `#[export_name]` is for Rust-defined functions.
-    pub link_name: Option<Symbol>,
+    /// The name this function will be imported/exported under. This can be set
+    /// using the `#[export_name = "..."]` or `#[link_name = "..."]` attribute
+    /// depending on if this is a function definition or foreign function.
+    pub symbol_name: Option<Symbol>,
     /// The `#[link_ordinal = "..."]` attribute, indicating an ordinal an
     /// imported function has in the dynamic library. Note that this must not
     /// be set when `link_name` is set. This is for foreign items with the
@@ -62,8 +56,8 @@ pub struct CodegenFnAttrs {
     /// The `#[link_section = "..."]` attribute, or what executable section this
     /// should be placed in.
     pub link_section: Option<Symbol>,
-    /// The `#[no_sanitize(...)]` attribute. Indicates sanitizers for which
-    /// instrumentation should be disabled inside the annotated function.
+    /// The `#[sanitize(xyz = "off")]` attribute. Indicates sanitizers for which
+    /// instrumentation should be disabled inside the function.
     pub no_sanitize: SanitizerSet,
     /// The `#[instruction_set(set)]` attribute. Indicates if the generated code should
     /// be generated against a specific instruction set. Only usable on architectures which allow
@@ -75,17 +69,25 @@ pub struct CodegenFnAttrs {
     /// The `#[patchable_function_entry(...)]` attribute. Indicates how many nops should be around
     /// the function entry.
     pub patchable_function_entry: Option<PatchableFunctionEntry>,
-    /// For the `#[autodiff]` macros.
-    pub autodiff_item: Option<AutoDiffAttrs>,
+}
+
+#[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable, PartialEq, Eq)]
+pub enum TargetFeatureKind {
+    /// The feature is implied by another feature, rather than explicitly added by the
+    /// `#[target_feature]` attribute
+    Implied,
+    /// The feature is added by the regular `target_feature` attribute.
+    Enabled,
+    /// The feature is added by the unsafe `force_target_feature` attribute.
+    Forced,
 }
 
 #[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)]
 pub struct TargetFeature {
     /// The name of the target feature (e.g. "avx")
     pub name: Symbol,
-    /// The feature is implied by another feature, rather than explicitly added by the
-    /// `#[target_feature]` attribute
-    pub implied: bool,
+    /// The way this feature was enabled.
+    pub kind: TargetFeatureKind,
 }
 
 #[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)]
@@ -158,6 +160,8 @@ bitflags::bitflags! {
         const ALLOCATOR_ZEROED          = 1 << 14;
         /// `#[no_builtins]`: indicates that disable implicit builtin knowledge of functions for the function.
         const NO_BUILTINS               = 1 << 15;
+        /// Marks foreign items, to make `contains_extern_indicator` cheaper.
+        const FOREIGN_ITEM              = 1 << 16;
     }
 }
 rustc_data_structures::external_bitflags_debug! { CodegenFnAttrFlags }
@@ -170,8 +174,7 @@ impl CodegenFnAttrs {
             flags: CodegenFnAttrFlags::empty(),
             inline: InlineAttr::None,
             optimize: OptimizeAttr::Default,
-            export_name: None,
-            link_name: None,
+            symbol_name: None,
             link_ordinal: None,
             target_features: vec![],
             safe_target_features: false,
@@ -182,7 +185,6 @@ impl CodegenFnAttrs {
             instruction_set: None,
             alignment: None,
             patchable_function_entry: None,
-            autodiff_item: None,
         }
     }
 
@@ -194,9 +196,13 @@ impl CodegenFnAttrs {
     ///
     /// Keep this in sync with the logic for the unused_attributes for `#[inline]` lint.
     pub fn contains_extern_indicator(&self) -> bool {
+        if self.flags.contains(CodegenFnAttrFlags::FOREIGN_ITEM) {
+            return false;
+        }
+
         self.flags.contains(CodegenFnAttrFlags::NO_MANGLE)
             || self.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL)
-            || self.export_name.is_some()
+            || self.symbol_name.is_some()
             || match self.linkage {
                 // These are private, so make sure we don't try to consider
                 // them external.
diff --git a/compiler/rustc_middle/src/middle/privacy.rs b/compiler/rustc_middle/src/middle/privacy.rs
index 785ddd1ee29..e3e04c9d180 100644
--- a/compiler/rustc_middle/src/middle/privacy.rs
+++ b/compiler/rustc_middle/src/middle/privacy.rs
@@ -181,11 +181,7 @@ impl EffectiveVisibilities {
             // nominal visibility. For some items nominal visibility doesn't make sense so we
             // don't check this condition for them.
             let is_impl = matches!(tcx.def_kind(def_id), DefKind::Impl { .. });
-            let is_associated_item_in_trait_impl = tcx
-                .impl_of_assoc(def_id.to_def_id())
-                .and_then(|impl_id| tcx.trait_id_of_impl(impl_id))
-                .is_some();
-            if !is_impl && !is_associated_item_in_trait_impl {
+            if !is_impl && tcx.trait_impl_of_assoc(def_id.to_def_id()).is_none() {
                 let nominal_vis = tcx.visibility(def_id);
                 if !nominal_vis.is_at_least(ev.reachable, tcx) {
                     span_bug!(
diff --git a/compiler/rustc_middle/src/middle/stability.rs b/compiler/rustc_middle/src/middle/stability.rs
index 4a19cf1563c..18520089e3e 100644
--- a/compiler/rustc_middle/src/middle/stability.rs
+++ b/compiler/rustc_middle/src/middle/stability.rs
@@ -4,7 +4,7 @@
 use std::num::NonZero;
 
 use rustc_ast::NodeId;
-use rustc_errors::{Applicability, Diag, EmissionGuarantee};
+use rustc_errors::{Applicability, Diag, EmissionGuarantee, LintBuffer};
 use rustc_feature::GateIssue;
 use rustc_hir::attrs::{DeprecatedSince, Deprecation};
 use rustc_hir::def_id::{DefId, LocalDefId};
@@ -12,7 +12,7 @@ use rustc_hir::{self as hir, ConstStability, DefaultBodyStability, HirId, Stabil
 use rustc_macros::{Decodable, Encodable, HashStable, Subdiagnostic};
 use rustc_session::Session;
 use rustc_session::lint::builtin::{DEPRECATED, DEPRECATED_IN_FUTURE, SOFT_UNSTABLE};
-use rustc_session::lint::{BuiltinLintDiag, DeprecatedSinceKind, Level, Lint, LintBuffer};
+use rustc_session::lint::{BuiltinLintDiag, DeprecatedSinceKind, Level, Lint};
 use rustc_session::parse::feature_err_issue;
 use rustc_span::{Span, Symbol, sym};
 use tracing::debug;
diff --git a/compiler/rustc_middle/src/mir/consts.rs b/compiler/rustc_middle/src/mir/consts.rs
index 96131d47a17..164433aede2 100644
--- a/compiler/rustc_middle/src/mir/consts.rs
+++ b/compiler/rustc_middle/src/mir/consts.rs
@@ -448,6 +448,11 @@ impl<'tcx> Const<'tcx> {
         Self::Val(val, ty)
     }
 
+    #[inline]
+    pub fn from_ty_value(tcx: TyCtxt<'tcx>, val: ty::Value<'tcx>) -> Self {
+        Self::Ty(val.ty, ty::Const::new_value(tcx, val.valtree, val.ty))
+    }
+
     pub fn from_bits(
         tcx: TyCtxt<'tcx>,
         bits: u128,
diff --git a/compiler/rustc_middle/src/mir/interpret/allocation.rs b/compiler/rustc_middle/src/mir/interpret/allocation.rs
index 27ead514531..2ea92a39d48 100644
--- a/compiler/rustc_middle/src/mir/interpret/allocation.rs
+++ b/compiler/rustc_middle/src/mir/interpret/allocation.rs
@@ -306,8 +306,6 @@ pub enum AllocError {
     ScalarSizeMismatch(ScalarSizeMismatch),
     /// Encountered a pointer where we needed raw bytes.
     ReadPointerAsInt(Option<BadBytesAccess>),
-    /// Partially overwriting a pointer.
-    OverwritePartialPointer(Size),
     /// Partially copying a pointer.
     ReadPartialPointer(Size),
     /// Using uninitialized data where it is not allowed.
@@ -331,9 +329,6 @@ impl AllocError {
             ReadPointerAsInt(info) => InterpErrorKind::Unsupported(
                 UnsupportedOpInfo::ReadPointerAsInt(info.map(|b| (alloc_id, b))),
             ),
-            OverwritePartialPointer(offset) => InterpErrorKind::Unsupported(
-                UnsupportedOpInfo::OverwritePartialPointer(Pointer::new(alloc_id, offset)),
-            ),
             ReadPartialPointer(offset) => InterpErrorKind::Unsupported(
                 UnsupportedOpInfo::ReadPartialPointer(Pointer::new(alloc_id, offset)),
             ),
@@ -633,11 +628,11 @@ impl<Prov: Provenance, Extra, Bytes: AllocBytes> Allocation<Prov, Extra, Bytes>
         &mut self,
         cx: &impl HasDataLayout,
         range: AllocRange,
-    ) -> AllocResult<&mut [u8]> {
+    ) -> &mut [u8] {
         self.mark_init(range, true);
-        self.provenance.clear(range, cx)?;
+        self.provenance.clear(range, cx);
 
-        Ok(&mut self.bytes[range.start.bytes_usize()..range.end().bytes_usize()])
+        &mut self.bytes[range.start.bytes_usize()..range.end().bytes_usize()]
     }
 
     /// A raw pointer variant of `get_bytes_unchecked_for_overwrite` that avoids invalidating existing immutable aliases
@@ -646,15 +641,15 @@ impl<Prov: Provenance, Extra, Bytes: AllocBytes> Allocation<Prov, Extra, Bytes>
         &mut self,
         cx: &impl HasDataLayout,
         range: AllocRange,
-    ) -> AllocResult<*mut [u8]> {
+    ) -> *mut [u8] {
         self.mark_init(range, true);
-        self.provenance.clear(range, cx)?;
+        self.provenance.clear(range, cx);
 
         assert!(range.end().bytes_usize() <= self.bytes.len()); // need to do our own bounds-check
         // Crucially, we go via `AllocBytes::as_mut_ptr`, not `AllocBytes::deref_mut`.
         let begin_ptr = self.bytes.as_mut_ptr().wrapping_add(range.start.bytes_usize());
         let len = range.end().bytes_usize() - range.start.bytes_usize();
-        Ok(ptr::slice_from_raw_parts_mut(begin_ptr, len))
+        ptr::slice_from_raw_parts_mut(begin_ptr, len)
     }
 
     /// This gives direct mutable access to the entire buffer, just exposing their internal state
@@ -723,26 +718,45 @@ impl<Prov: Provenance, Extra, Bytes: AllocBytes> Allocation<Prov, Extra, Bytes>
                 let ptr = Pointer::new(prov, Size::from_bytes(bits));
                 return Ok(Scalar::from_pointer(ptr, cx));
             }
-
-            // If we can work on pointers byte-wise, join the byte-wise provenances.
-            if Prov::OFFSET_IS_ADDR {
-                let mut prov = self.provenance.get(range.start, cx);
+            // The other easy case is total absence of provenance.
+            if self.provenance.range_empty(range, cx) {
+                return Ok(Scalar::from_uint(bits, range.size));
+            }
+            // If we get here, we have to check per-byte provenance, and join them together.
+            let prov = 'prov: {
+                // Initialize with first fragment. Must have index 0.
+                let Some((mut joint_prov, 0)) = self.provenance.get_byte(range.start, cx) else {
+                    break 'prov None;
+                };
+                // Update with the remaining fragments.
                 for offset in Size::from_bytes(1)..range.size {
-                    let this_prov = self.provenance.get(range.start + offset, cx);
-                    prov = Prov::join(prov, this_prov);
+                    // Ensure there is provenance here and it has the right index.
+                    let Some((frag_prov, frag_idx)) =
+                        self.provenance.get_byte(range.start + offset, cx)
+                    else {
+                        break 'prov None;
+                    };
+                    // Wildcard provenance is allowed to come with any index (this is needed
+                    // for Miri's native-lib mode to work).
+                    if u64::from(frag_idx) != offset.bytes() && Some(frag_prov) != Prov::WILDCARD {
+                        break 'prov None;
+                    }
+                    // Merge this byte's provenance with the previous ones.
+                    joint_prov = match Prov::join(joint_prov, frag_prov) {
+                        Some(prov) => prov,
+                        None => break 'prov None,
+                    };
                 }
-                // Now use this provenance.
-                let ptr = Pointer::new(prov, Size::from_bytes(bits));
-                return Ok(Scalar::from_maybe_pointer(ptr, cx));
-            } else {
-                // Without OFFSET_IS_ADDR, the only remaining case we can handle is total absence of
-                // provenance.
-                if self.provenance.range_empty(range, cx) {
-                    return Ok(Scalar::from_uint(bits, range.size));
-                }
-                // Else we have mixed provenance, that doesn't work.
+                break 'prov Some(joint_prov);
+            };
+            if prov.is_none() && !Prov::OFFSET_IS_ADDR {
+                // There are some bytes with provenance here but overall the provenance does not add up.
+                // We need `OFFSET_IS_ADDR` to fall back to no-provenance here; without that option, we must error.
                 return Err(AllocError::ReadPartialPointer(range.start));
             }
+            // We can use this provenance.
+            let ptr = Pointer::new(prov, Size::from_bytes(bits));
+            return Ok(Scalar::from_maybe_pointer(ptr, cx));
         } else {
             // We are *not* reading a pointer.
             // If we can just ignore provenance or there is none, that's easy.
@@ -782,7 +796,7 @@ impl<Prov: Provenance, Extra, Bytes: AllocBytes> Allocation<Prov, Extra, Bytes>
 
         let endian = cx.data_layout().endian;
         // Yes we do overwrite all the bytes in `dst`.
-        let dst = self.get_bytes_unchecked_for_overwrite(cx, range)?;
+        let dst = self.get_bytes_unchecked_for_overwrite(cx, range);
         write_target_uint(endian, dst, bytes).unwrap();
 
         // See if we have to also store some provenance.
@@ -795,10 +809,9 @@ impl<Prov: Provenance, Extra, Bytes: AllocBytes> Allocation<Prov, Extra, Bytes>
     }
 
     /// Write "uninit" to the given memory range.
-    pub fn write_uninit(&mut self, cx: &impl HasDataLayout, range: AllocRange) -> AllocResult {
+    pub fn write_uninit(&mut self, cx: &impl HasDataLayout, range: AllocRange) {
         self.mark_init(range, false);
-        self.provenance.clear(range, cx)?;
-        Ok(())
+        self.provenance.clear(range, cx);
     }
 
     /// Mark all bytes in the given range as initialised and reset the provenance
@@ -817,9 +830,12 @@ impl<Prov: Provenance, Extra, Bytes: AllocBytes> Allocation<Prov, Extra, Bytes>
     }
 
     /// Remove all provenance in the given memory range.
-    pub fn clear_provenance(&mut self, cx: &impl HasDataLayout, range: AllocRange) -> AllocResult {
-        self.provenance.clear(range, cx)?;
-        return Ok(());
+    pub fn clear_provenance(&mut self, cx: &impl HasDataLayout, range: AllocRange) {
+        self.provenance.clear(range, cx);
+    }
+
+    pub fn provenance_merge_bytes(&mut self, cx: &impl HasDataLayout) -> bool {
+        self.provenance.merge_bytes(cx)
     }
 
     /// Applies a previously prepared provenance copy.
diff --git a/compiler/rustc_middle/src/mir/interpret/allocation/provenance_map.rs b/compiler/rustc_middle/src/mir/interpret/allocation/provenance_map.rs
index 119d4be64e6..dbbd95408c8 100644
--- a/compiler/rustc_middle/src/mir/interpret/allocation/provenance_map.rs
+++ b/compiler/rustc_middle/src/mir/interpret/allocation/provenance_map.rs
@@ -10,7 +10,7 @@ use rustc_macros::HashStable;
 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
 use tracing::trace;
 
-use super::{AllocError, AllocRange, AllocResult, CtfeProvenance, Provenance, alloc_range};
+use super::{AllocRange, CtfeProvenance, Provenance, alloc_range};
 
 /// Stores the provenance information of pointers stored in memory.
 #[derive(Clone, PartialEq, Eq, Hash, Debug)]
@@ -19,25 +19,25 @@ pub struct ProvenanceMap<Prov = CtfeProvenance> {
     /// `Provenance` in this map applies from the given offset for an entire pointer-size worth of
     /// bytes. Two entries in this map are always at least a pointer size apart.
     ptrs: SortedMap<Size, Prov>,
-    /// Provenance in this map only applies to the given single byte.
-    /// This map is disjoint from the previous. It will always be empty when
-    /// `Prov::OFFSET_IS_ADDR` is false.
-    bytes: Option<Box<SortedMap<Size, Prov>>>,
+    /// This stores byte-sized provenance fragments.
+    /// The `u8` indicates the position of this byte inside its original pointer.
+    /// If the bytes are re-assembled in their original order, the pointer can be used again.
+    /// Wildcard provenance is allowed to have index 0 everywhere.
+    bytes: Option<Box<SortedMap<Size, (Prov, u8)>>>,
 }
 
 // These impls are generic over `Prov` since `CtfeProvenance` is only decodable/encodable
 // for some particular `D`/`S`.
 impl<D: Decoder, Prov: Provenance + Decodable<D>> Decodable<D> for ProvenanceMap<Prov> {
     fn decode(d: &mut D) -> Self {
-        assert!(!Prov::OFFSET_IS_ADDR); // only `CtfeProvenance` is ever serialized
+        // `bytes` is not in the serialized format
         Self { ptrs: Decodable::decode(d), bytes: None }
     }
 }
 impl<S: Encoder, Prov: Provenance + Encodable<S>> Encodable<S> for ProvenanceMap<Prov> {
     fn encode(&self, s: &mut S) {
         let Self { ptrs, bytes } = self;
-        assert!(!Prov::OFFSET_IS_ADDR); // only `CtfeProvenance` is ever serialized
-        debug_assert!(bytes.is_none()); // without `OFFSET_IS_ADDR`, this is always empty
+        assert!(bytes.is_none()); // interning refuses allocations with pointer fragments
         ptrs.encode(s)
     }
 }
@@ -58,10 +58,10 @@ impl ProvenanceMap {
     /// Give access to the ptr-sized provenances (which can also be thought of as relocations, and
     /// indeed that is how codegen treats them).
     ///
-    /// Only exposed with `CtfeProvenance` provenance, since it panics if there is bytewise provenance.
+    /// Only use on interned allocations, as other allocations may have per-byte provenance!
     #[inline]
     pub fn ptrs(&self) -> &SortedMap<Size, CtfeProvenance> {
-        debug_assert!(self.bytes.is_none()); // `CtfeProvenance::OFFSET_IS_ADDR` is false so this cannot fail
+        assert!(self.bytes.is_none(), "`ptrs()` called on non-interned allocation");
         &self.ptrs
     }
 }
@@ -88,12 +88,12 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
     }
 
     /// `pm.range_ptrs_is_empty(r, cx)` == `pm.range_ptrs_get(r, cx).is_empty()`, but is faster.
-    pub(super) fn range_ptrs_is_empty(&self, range: AllocRange, cx: &impl HasDataLayout) -> bool {
+    fn range_ptrs_is_empty(&self, range: AllocRange, cx: &impl HasDataLayout) -> bool {
         self.ptrs.range_is_empty(Self::adjusted_range_ptrs(range, cx))
     }
 
     /// Returns all byte-wise provenance in the given range.
-    fn range_bytes_get(&self, range: AllocRange) -> &[(Size, Prov)] {
+    fn range_bytes_get(&self, range: AllocRange) -> &[(Size, (Prov, u8))] {
         if let Some(bytes) = self.bytes.as_ref() {
             bytes.range(range.start..range.end())
         } else {
@@ -107,19 +107,58 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
     }
 
     /// Get the provenance of a single byte.
-    pub fn get(&self, offset: Size, cx: &impl HasDataLayout) -> Option<Prov> {
+    pub fn get_byte(&self, offset: Size, cx: &impl HasDataLayout) -> Option<(Prov, u8)> {
         let prov = self.range_ptrs_get(alloc_range(offset, Size::from_bytes(1)), cx);
         debug_assert!(prov.len() <= 1);
         if let Some(entry) = prov.first() {
             // If it overlaps with this byte, it is on this byte.
             debug_assert!(self.bytes.as_ref().is_none_or(|b| !b.contains_key(&offset)));
-            Some(entry.1)
+            Some((entry.1, (offset - entry.0).bytes() as u8))
         } else {
             // Look up per-byte provenance.
             self.bytes.as_ref().and_then(|b| b.get(&offset).copied())
         }
     }
 
+    /// Gets the provenances of all bytes (including from pointers) in a range.
+    pub fn get_range(
+        &self,
+        cx: &impl HasDataLayout,
+        range: AllocRange,
+    ) -> impl Iterator<Item = Prov> {
+        let ptr_provs = self.range_ptrs_get(range, cx).iter().map(|(_, p)| *p);
+        let byte_provs = self.range_bytes_get(range).iter().map(|(_, (p, _))| *p);
+        ptr_provs.chain(byte_provs)
+    }
+
+    /// Attempt to merge per-byte provenance back into ptr chunks, if the right fragments
+    /// sit next to each other. Return `false` is that is not possible due to partial pointers.
+    pub fn merge_bytes(&mut self, cx: &impl HasDataLayout) -> bool {
+        let Some(bytes) = self.bytes.as_deref_mut() else {
+            return true;
+        };
+        let ptr_size = cx.data_layout().pointer_size();
+        while let Some((offset, (prov, _))) = bytes.iter().next().copied() {
+            // Check if this fragment starts a pointer.
+            let range = offset..offset + ptr_size;
+            let frags = bytes.range(range.clone());
+            if frags.len() != ptr_size.bytes_usize() {
+                return false;
+            }
+            for (idx, (_offset, (frag_prov, frag_idx))) in frags.iter().copied().enumerate() {
+                if frag_prov != prov || frag_idx != idx as u8 {
+                    return false;
+                }
+            }
+            // Looks like a pointer! Move it over to the ptr provenance map.
+            bytes.remove_range(range);
+            self.ptrs.insert(offset, prov);
+        }
+        // We managed to convert everything into whole pointers.
+        self.bytes = None;
+        true
+    }
+
     /// Check if there is ptr-sized provenance at the given index.
     /// Does not mean anything for bytewise provenance! But can be useful as an optimization.
     pub fn get_ptr(&self, offset: Size) -> Option<Prov> {
@@ -137,7 +176,7 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
 
     /// Yields all the provenances stored in this map.
     pub fn provenances(&self) -> impl Iterator<Item = Prov> {
-        let bytes = self.bytes.iter().flat_map(|b| b.values());
+        let bytes = self.bytes.iter().flat_map(|b| b.values().map(|(p, _i)| p));
         self.ptrs.values().chain(bytes).copied()
     }
 
@@ -148,16 +187,12 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
 
     /// Removes all provenance inside the given range.
     /// If there is provenance overlapping with the edges, might result in an error.
-    pub fn clear(&mut self, range: AllocRange, cx: &impl HasDataLayout) -> AllocResult {
+    pub fn clear(&mut self, range: AllocRange, cx: &impl HasDataLayout) {
         let start = range.start;
         let end = range.end();
         // Clear the bytewise part -- this is easy.
-        if Prov::OFFSET_IS_ADDR {
-            if let Some(bytes) = self.bytes.as_mut() {
-                bytes.remove_range(start..end);
-            }
-        } else {
-            debug_assert!(self.bytes.is_none());
+        if let Some(bytes) = self.bytes.as_mut() {
+            bytes.remove_range(start..end);
         }
 
         let pointer_size = cx.data_layout().pointer_size();
@@ -168,7 +203,7 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
             // Find all provenance overlapping the given range.
             if self.range_ptrs_is_empty(range, cx) {
                 // No provenance in this range, we are done. This is the common case.
-                return Ok(());
+                return;
             }
 
             // This redoes some of the work of `range_get_ptrs_is_empty`, but this path is much
@@ -179,28 +214,20 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
 
         // We need to handle clearing the provenance from parts of a pointer.
         if first < start {
-            if !Prov::OFFSET_IS_ADDR {
-                // We can't split up the provenance into less than a pointer.
-                return Err(AllocError::OverwritePartialPointer(first));
-            }
             // Insert the remaining part in the bytewise provenance.
             let prov = self.ptrs[&first];
             let bytes = self.bytes.get_or_insert_with(Box::default);
             for offset in first..start {
-                bytes.insert(offset, prov);
+                bytes.insert(offset, (prov, (offset - first).bytes() as u8));
             }
         }
         if last > end {
             let begin_of_last = last - pointer_size;
-            if !Prov::OFFSET_IS_ADDR {
-                // We can't split up the provenance into less than a pointer.
-                return Err(AllocError::OverwritePartialPointer(begin_of_last));
-            }
             // Insert the remaining part in the bytewise provenance.
             let prov = self.ptrs[&begin_of_last];
             let bytes = self.bytes.get_or_insert_with(Box::default);
             for offset in end..last {
-                bytes.insert(offset, prov);
+                bytes.insert(offset, (prov, (offset - begin_of_last).bytes() as u8));
             }
         }
 
@@ -208,8 +235,6 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
         // Since provenance do not overlap, we know that removing until `last` (exclusive) is fine,
         // i.e., this will not remove any other provenance just after the ones we care about.
         self.ptrs.remove_range(first..last);
-
-        Ok(())
     }
 
     /// Overwrites all provenance in the given range with wildcard provenance.
@@ -218,10 +243,6 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
     ///
     /// Provided for usage in Miri and panics otherwise.
     pub fn write_wildcards(&mut self, cx: &impl HasDataLayout, range: AllocRange) {
-        assert!(
-            Prov::OFFSET_IS_ADDR,
-            "writing wildcard provenance is not supported when `OFFSET_IS_ADDR` is false"
-        );
         let wildcard = Prov::WILDCARD.unwrap();
 
         let bytes = self.bytes.get_or_insert_with(Box::default);
@@ -229,21 +250,22 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
         // Remove pointer provenances that overlap with the range, then readd the edge ones bytewise.
         let ptr_range = Self::adjusted_range_ptrs(range, cx);
         let ptrs = self.ptrs.range(ptr_range.clone());
-        if let Some((offset, prov)) = ptrs.first() {
-            for byte_ofs in *offset..range.start {
-                bytes.insert(byte_ofs, *prov);
+        if let Some((offset, prov)) = ptrs.first().copied() {
+            for byte_ofs in offset..range.start {
+                bytes.insert(byte_ofs, (prov, (byte_ofs - offset).bytes() as u8));
             }
         }
-        if let Some((offset, prov)) = ptrs.last() {
-            for byte_ofs in range.end()..*offset + cx.data_layout().pointer_size() {
-                bytes.insert(byte_ofs, *prov);
+        if let Some((offset, prov)) = ptrs.last().copied() {
+            for byte_ofs in range.end()..offset + cx.data_layout().pointer_size() {
+                bytes.insert(byte_ofs, (prov, (byte_ofs - offset).bytes() as u8));
             }
         }
         self.ptrs.remove_range(ptr_range);
 
         // Overwrite bytewise provenance.
         for offset in range.start..range.end() {
-            bytes.insert(offset, wildcard);
+            // The fragment index does not matter for wildcard provenance.
+            bytes.insert(offset, (wildcard, 0));
         }
     }
 }
@@ -253,7 +275,7 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
 /// Offsets are already adjusted to the destination allocation.
 pub struct ProvenanceCopy<Prov> {
     dest_ptrs: Option<Box<[(Size, Prov)]>>,
-    dest_bytes: Option<Box<[(Size, Prov)]>>,
+    dest_bytes: Option<Box<[(Size, (Prov, u8))]>>,
 }
 
 impl<Prov: Provenance> ProvenanceMap<Prov> {
@@ -263,7 +285,7 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
         dest: Size,
         count: u64,
         cx: &impl HasDataLayout,
-    ) -> AllocResult<ProvenanceCopy<Prov>> {
+    ) -> ProvenanceCopy<Prov> {
         let shift_offset = move |idx, offset| {
             // compute offset for current repetition
             let dest_offset = dest + src.size * idx; // `Size` operations
@@ -301,24 +323,16 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
         let mut dest_bytes_box = None;
         let begin_overlap = self.range_ptrs_get(alloc_range(src.start, Size::ZERO), cx).first();
         let end_overlap = self.range_ptrs_get(alloc_range(src.end(), Size::ZERO), cx).first();
-        if !Prov::OFFSET_IS_ADDR {
-            // There can't be any bytewise provenance, and we cannot split up the begin/end overlap.
-            if let Some(entry) = begin_overlap {
-                return Err(AllocError::ReadPartialPointer(entry.0));
-            }
-            if let Some(entry) = end_overlap {
-                return Err(AllocError::ReadPartialPointer(entry.0));
-            }
-            debug_assert!(self.bytes.is_none());
-        } else {
-            let mut bytes = Vec::new();
+        // We only need to go here if there is some overlap or some bytewise provenance.
+        if begin_overlap.is_some() || end_overlap.is_some() || self.bytes.is_some() {
+            let mut bytes: Vec<(Size, (Prov, u8))> = Vec::new();
             // First, if there is a part of a pointer at the start, add that.
             if let Some(entry) = begin_overlap {
                 trace!("start overlapping entry: {entry:?}");
                 // For really small copies, make sure we don't run off the end of the `src` range.
                 let entry_end = cmp::min(entry.0 + ptr_size, src.end());
                 for offset in src.start..entry_end {
-                    bytes.push((offset, entry.1));
+                    bytes.push((offset, (entry.1, (offset - entry.0).bytes() as u8)));
                 }
             } else {
                 trace!("no start overlapping entry");
@@ -334,8 +348,9 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
                 let entry_start = cmp::max(entry.0, src.start);
                 for offset in entry_start..src.end() {
                     if bytes.last().is_none_or(|bytes_entry| bytes_entry.0 < offset) {
-                        // The last entry, if it exists, has a lower offset than us.
-                        bytes.push((offset, entry.1));
+                        // The last entry, if it exists, has a lower offset than us, so we
+                        // can add it at the end and remain sorted.
+                        bytes.push((offset, (entry.1, (offset - entry.0).bytes() as u8)));
                     } else {
                         // There already is an entry for this offset in there! This can happen when the
                         // start and end range checks actually end up hitting the same pointer, so we
@@ -358,7 +373,7 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
             dest_bytes_box = Some(dest_bytes.into_boxed_slice());
         }
 
-        Ok(ProvenanceCopy { dest_ptrs: dest_ptrs_box, dest_bytes: dest_bytes_box })
+        ProvenanceCopy { dest_ptrs: dest_ptrs_box, dest_bytes: dest_bytes_box }
     }
 
     /// Applies a provenance copy.
@@ -368,14 +383,10 @@ impl<Prov: Provenance> ProvenanceMap<Prov> {
         if let Some(dest_ptrs) = copy.dest_ptrs {
             self.ptrs.insert_presorted(dest_ptrs.into());
         }
-        if Prov::OFFSET_IS_ADDR {
-            if let Some(dest_bytes) = copy.dest_bytes
-                && !dest_bytes.is_empty()
-            {
-                self.bytes.get_or_insert_with(Box::default).insert_presorted(dest_bytes.into());
-            }
-        } else {
-            debug_assert!(copy.dest_bytes.is_none());
+        if let Some(dest_bytes) = copy.dest_bytes
+            && !dest_bytes.is_empty()
+        {
+            self.bytes.get_or_insert_with(Box::default).insert_presorted(dest_bytes.into());
         }
     }
 }
diff --git a/compiler/rustc_middle/src/mir/interpret/error.rs b/compiler/rustc_middle/src/mir/interpret/error.rs
index 77427a12d11..7c72a8ec243 100644
--- a/compiler/rustc_middle/src/mir/interpret/error.rs
+++ b/compiler/rustc_middle/src/mir/interpret/error.rs
@@ -582,9 +582,6 @@ pub enum UnsupportedOpInfo {
     //
     // The variants below are only reachable from CTFE/const prop, miri will never emit them.
     //
-    /// Overwriting parts of a pointer; without knowing absolute addresses, the resulting state
-    /// cannot be represented by the CTFE interpreter.
-    OverwritePartialPointer(Pointer<AllocId>),
     /// Attempting to read or copy parts of a pointer to somewhere else; without knowing absolute
     /// addresses, the resulting state cannot be represented by the CTFE interpreter.
     ReadPartialPointer(Pointer<AllocId>),
diff --git a/compiler/rustc_middle/src/mir/interpret/pointer.rs b/compiler/rustc_middle/src/mir/interpret/pointer.rs
index e25ff7651f6..c581b2ebf09 100644
--- a/compiler/rustc_middle/src/mir/interpret/pointer.rs
+++ b/compiler/rustc_middle/src/mir/interpret/pointer.rs
@@ -56,7 +56,7 @@ impl<T: HasDataLayout> PointerArithmetic for T {}
 /// mostly opaque; the `Machine` trait extends it with some more operations that also have access to
 /// some global state.
 /// The `Debug` rendering is used to display bare provenance, and for the default impl of `fmt`.
-pub trait Provenance: Copy + fmt::Debug + 'static {
+pub trait Provenance: Copy + PartialEq + fmt::Debug + 'static {
     /// Says whether the `offset` field of `Pointer`s with this provenance is the actual physical address.
     /// - If `false`, the offset *must* be relative. This means the bytes representing a pointer are
     ///   different from what the Abstract Machine prescribes, so the interpreter must prevent any
@@ -79,7 +79,7 @@ pub trait Provenance: Copy + fmt::Debug + 'static {
     fn get_alloc_id(self) -> Option<AllocId>;
 
     /// Defines the 'join' of provenance: what happens when doing a pointer load and different bytes have different provenance.
-    fn join(left: Option<Self>, right: Option<Self>) -> Option<Self>;
+    fn join(left: Self, right: Self) -> Option<Self>;
 }
 
 /// The type of provenance in the compile-time interpreter.
@@ -192,8 +192,8 @@ impl Provenance for CtfeProvenance {
         Some(self.alloc_id())
     }
 
-    fn join(_left: Option<Self>, _right: Option<Self>) -> Option<Self> {
-        panic!("merging provenance is not supported when `OFFSET_IS_ADDR` is false")
+    fn join(left: Self, right: Self) -> Option<Self> {
+        if left == right { Some(left) } else { None }
     }
 }
 
@@ -224,8 +224,8 @@ impl Provenance for AllocId {
         Some(self)
     }
 
-    fn join(_left: Option<Self>, _right: Option<Self>) -> Option<Self> {
-        panic!("merging provenance is not supported when `OFFSET_IS_ADDR` is false")
+    fn join(_left: Self, _right: Self) -> Option<Self> {
+        unreachable!()
     }
 }
 
diff --git a/compiler/rustc_middle/src/mir/mod.rs b/compiler/rustc_middle/src/mir/mod.rs
index c55c7fc6002..c977e5329c2 100644
--- a/compiler/rustc_middle/src/mir/mod.rs
+++ b/compiler/rustc_middle/src/mir/mod.rs
@@ -115,48 +115,6 @@ impl MirPhase {
             MirPhase::Runtime(runtime_phase) => (3, 1 + runtime_phase as usize),
         }
     }
-
-    /// Parses a `MirPhase` from a pair of strings. Panics if this isn't possible for any reason.
-    pub fn parse(dialect: String, phase: Option<String>) -> Self {
-        match &*dialect.to_ascii_lowercase() {
-            "built" => {
-                assert!(phase.is_none(), "Cannot specify a phase for `Built` MIR");
-                MirPhase::Built
-            }
-            "analysis" => Self::Analysis(AnalysisPhase::parse(phase)),
-            "runtime" => Self::Runtime(RuntimePhase::parse(phase)),
-            _ => bug!("Unknown MIR dialect: '{}'", dialect),
-        }
-    }
-}
-
-impl AnalysisPhase {
-    pub fn parse(phase: Option<String>) -> Self {
-        let Some(phase) = phase else {
-            return Self::Initial;
-        };
-
-        match &*phase.to_ascii_lowercase() {
-            "initial" => Self::Initial,
-            "post_cleanup" | "post-cleanup" | "postcleanup" => Self::PostCleanup,
-            _ => bug!("Unknown analysis phase: '{}'", phase),
-        }
-    }
-}
-
-impl RuntimePhase {
-    pub fn parse(phase: Option<String>) -> Self {
-        let Some(phase) = phase else {
-            return Self::Initial;
-        };
-
-        match &*phase.to_ascii_lowercase() {
-            "initial" => Self::Initial,
-            "post_cleanup" | "post-cleanup" | "postcleanup" => Self::PostCleanup,
-            "optimized" => Self::Optimized,
-            _ => bug!("Unknown runtime phase: '{}'", phase),
-        }
-    }
 }
 
 /// Where a specific `mir::Body` comes from.
diff --git a/compiler/rustc_middle/src/mir/mono.rs b/compiler/rustc_middle/src/mir/mono.rs
index e5864660575..6b45b2dc3ff 100644
--- a/compiler/rustc_middle/src/mir/mono.rs
+++ b/compiler/rustc_middle/src/mir/mono.rs
@@ -2,7 +2,6 @@ use std::borrow::Cow;
 use std::fmt;
 use std::hash::Hash;
 
-use rustc_ast::expand::autodiff_attrs::AutoDiffItem;
 use rustc_data_structures::base_n::{BaseNString, CASE_INSENSITIVE, ToBaseN};
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::fx::FxIndexMap;
@@ -10,9 +9,8 @@ use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHas
 use rustc_data_structures::unord::UnordMap;
 use rustc_hashes::Hash128;
 use rustc_hir::ItemId;
-use rustc_hir::attrs::InlineAttr;
+use rustc_hir::attrs::{InlineAttr, Linkage};
 use rustc_hir::def_id::{CrateNum, DefId, DefIdSet, LOCAL_CRATE};
-use rustc_index::Idx;
 use rustc_macros::{HashStable, TyDecodable, TyEncodable};
 use rustc_query_system::ich::StableHashingContext;
 use rustc_session::config::OptLevel;
@@ -337,7 +335,6 @@ impl ToStableHashKey<StableHashingContext<'_>> for MonoItem<'_> {
 pub struct MonoItemPartitions<'tcx> {
     pub codegen_units: &'tcx [CodegenUnit<'tcx>],
     pub all_mono_items: &'tcx DefIdSet,
-    pub autodiff_items: &'tcx [AutoDiffItem],
 }
 
 #[derive(Debug, HashStable)]
@@ -369,22 +366,6 @@ pub struct MonoItemData {
     pub size_estimate: usize,
 }
 
-/// Specifies the linkage type for a `MonoItem`.
-///
-/// See <https://llvm.org/docs/LangRef.html#linkage-types> for more details about these variants.
-#[derive(Copy, Clone, PartialEq, Debug, TyEncodable, TyDecodable, HashStable)]
-pub enum Linkage {
-    External,
-    AvailableExternally,
-    LinkOnceAny,
-    LinkOnceODR,
-    WeakAny,
-    WeakODR,
-    Internal,
-    ExternalWeak,
-    Common,
-}
-
 /// Specifies the symbol visibility with regards to dynamic linking.
 ///
 /// Visibility doesn't have any effect when linkage is internal.
@@ -526,45 +507,68 @@ impl<'tcx> CodegenUnit<'tcx> {
         tcx: TyCtxt<'tcx>,
     ) -> Vec<(MonoItem<'tcx>, MonoItemData)> {
         // The codegen tests rely on items being process in the same order as
-        // they appear in the file, so for local items, we sort by node_id first
+        // they appear in the file, so for local items, we sort by span first
         #[derive(PartialEq, Eq, PartialOrd, Ord)]
-        struct ItemSortKey<'tcx>(Option<usize>, SymbolName<'tcx>);
-
+        struct ItemSortKey<'tcx>(Option<Span>, SymbolName<'tcx>);
+
+        // We only want to take HirIds of user-defines instances into account.
+        // The others don't matter for the codegen tests and can even make item
+        // order unstable.
+        fn local_item_id<'tcx>(item: MonoItem<'tcx>) -> Option<DefId> {
+            match item {
+                MonoItem::Fn(ref instance) => match instance.def {
+                    InstanceKind::Item(def) => def.as_local().map(|_| def),
+                    InstanceKind::VTableShim(..)
+                    | InstanceKind::ReifyShim(..)
+                    | InstanceKind::Intrinsic(..)
+                    | InstanceKind::FnPtrShim(..)
+                    | InstanceKind::Virtual(..)
+                    | InstanceKind::ClosureOnceShim { .. }
+                    | InstanceKind::ConstructCoroutineInClosureShim { .. }
+                    | InstanceKind::DropGlue(..)
+                    | InstanceKind::CloneShim(..)
+                    | InstanceKind::ThreadLocalShim(..)
+                    | InstanceKind::FnPtrAddrShim(..)
+                    | InstanceKind::AsyncDropGlue(..)
+                    | InstanceKind::FutureDropPollShim(..)
+                    | InstanceKind::AsyncDropGlueCtorShim(..) => None,
+                },
+                MonoItem::Static(def_id) => def_id.as_local().map(|_| def_id),
+                MonoItem::GlobalAsm(item_id) => Some(item_id.owner_id.def_id.to_def_id()),
+            }
+        }
         fn item_sort_key<'tcx>(tcx: TyCtxt<'tcx>, item: MonoItem<'tcx>) -> ItemSortKey<'tcx> {
             ItemSortKey(
-                match item {
-                    MonoItem::Fn(ref instance) => {
-                        match instance.def {
-                            // We only want to take HirIds of user-defined
-                            // instances into account. The others don't matter for
-                            // the codegen tests and can even make item order
-                            // unstable.
-                            InstanceKind::Item(def) => def.as_local().map(Idx::index),
-                            InstanceKind::VTableShim(..)
-                            | InstanceKind::ReifyShim(..)
-                            | InstanceKind::Intrinsic(..)
-                            | InstanceKind::FnPtrShim(..)
-                            | InstanceKind::Virtual(..)
-                            | InstanceKind::ClosureOnceShim { .. }
-                            | InstanceKind::ConstructCoroutineInClosureShim { .. }
-                            | InstanceKind::DropGlue(..)
-                            | InstanceKind::CloneShim(..)
-                            | InstanceKind::ThreadLocalShim(..)
-                            | InstanceKind::FnPtrAddrShim(..)
-                            | InstanceKind::AsyncDropGlue(..)
-                            | InstanceKind::FutureDropPollShim(..)
-                            | InstanceKind::AsyncDropGlueCtorShim(..) => None,
-                        }
-                    }
-                    MonoItem::Static(def_id) => def_id.as_local().map(Idx::index),
-                    MonoItem::GlobalAsm(item_id) => Some(item_id.owner_id.def_id.index()),
-                },
+                local_item_id(item)
+                    .map(|def_id| tcx.def_span(def_id).find_ancestor_not_from_macro())
+                    .flatten(),
                 item.symbol_name(tcx),
             )
         }
 
         let mut items: Vec<_> = self.items().iter().map(|(&i, &data)| (i, data)).collect();
-        items.sort_by_cached_key(|&(i, _)| item_sort_key(tcx, i));
+        if !tcx.sess.opts.unstable_opts.codegen_source_order {
+            // In this case, we do not need to keep the items in any specific order, as the input
+            // is already deterministic.
+            //
+            // However, it seems that moving related things (such as different
+            // monomorphizations of the same function) close to one another is actually beneficial
+            // for LLVM performance.
+            // LLVM will codegen the items in the order we pass them to it, and when it handles
+            // similar things in succession, it seems that it leads to better cache utilization,
+            // less branch mispredictions and in general to better performance.
+            // For example, if we have functions `a`, `c::<u32>`, `b`, `c::<i16>`, `d` and
+            // `c::<bool>`, it seems that it helps LLVM's performance to codegen the three `c`
+            // instantiations right after one another, as they will likely reference similar types,
+            // call similar functions, etc.
+            //
+            // See https://github.com/rust-lang/rust/pull/145358 for more details.
+            //
+            // Sorting by symbol name should not incur any new non-determinism.
+            items.sort_by_cached_key(|&(i, _)| i.symbol_name(tcx));
+        } else {
+            items.sort_by_cached_key(|&(i, _)| item_sort_key(tcx, i));
+        }
         items
     }
 
diff --git a/compiler/rustc_middle/src/mir/pretty.rs b/compiler/rustc_middle/src/mir/pretty.rs
index 84abcf550d2..128ae8549f7 100644
--- a/compiler/rustc_middle/src/mir/pretty.rs
+++ b/compiler/rustc_middle/src/mir/pretty.rs
@@ -929,7 +929,10 @@ impl<'tcx> TerminatorKind<'tcx> {
             }
             Yield { value, resume_arg, .. } => write!(fmt, "{resume_arg:?} = yield({value:?})"),
             Unreachable => write!(fmt, "unreachable"),
-            Drop { place, .. } => write!(fmt, "drop({place:?})"),
+            Drop { place, async_fut: None, .. } => write!(fmt, "drop({place:?})"),
+            Drop { place, async_fut: Some(async_fut), .. } => {
+                write!(fmt, "async drop({place:?}; poll={async_fut:?})")
+            }
             Call { func, args, destination, .. } => {
                 write!(fmt, "{destination:?} = ")?;
                 write!(fmt, "{func:?}(")?;
@@ -1789,7 +1792,7 @@ pub fn write_allocation_bytes<'tcx, Prov: Provenance, Extra, Bytes: AllocBytes>(
                 ascii.push('╼');
                 i += ptr_size;
             }
-        } else if let Some(prov) = alloc.provenance().get(i, &tcx) {
+        } else if let Some((prov, idx)) = alloc.provenance().get_byte(i, &tcx) {
             // Memory with provenance must be defined
             assert!(
                 alloc.init_mask().is_range_initialized(alloc_range(i, Size::from_bytes(1))).is_ok()
@@ -1799,7 +1802,7 @@ pub fn write_allocation_bytes<'tcx, Prov: Provenance, Extra, Bytes: AllocBytes>(
             // Format is similar to "oversized" above.
             let j = i.bytes_usize();
             let c = alloc.inspect_with_uninit_and_ptr_outside_interpreter(j..j + 1)[0];
-            write!(w, "╾{c:02x}{prov:#?} (1 ptr byte)╼")?;
+            write!(w, "╾{c:02x}{prov:#?} (ptr fragment {idx})╼")?;
             i += Size::from_bytes(1);
         } else if alloc
             .init_mask()
@@ -1932,7 +1935,7 @@ fn pretty_print_const_value_tcx<'tcx>(
                         let args = tcx.lift(args).unwrap();
                         let mut p = FmtPrinter::new(tcx, Namespace::ValueNS);
                         p.print_alloc_ids = true;
-                        p.print_value_path(variant_def.def_id, args)?;
+                        p.pretty_print_value_path(variant_def.def_id, args)?;
                         fmt.write_str(&p.into_buffer())?;
 
                         match variant_def.ctor_kind() {
@@ -1974,7 +1977,7 @@ fn pretty_print_const_value_tcx<'tcx>(
         (ConstValue::ZeroSized, ty::FnDef(d, s)) => {
             let mut p = FmtPrinter::new(tcx, Namespace::ValueNS);
             p.print_alloc_ids = true;
-            p.print_value_path(*d, s)?;
+            p.pretty_print_value_path(*d, s)?;
             fmt.write_str(&p.into_buffer())?;
             return Ok(());
         }
diff --git a/compiler/rustc_middle/src/mir/query.rs b/compiler/rustc_middle/src/mir/query.rs
index a8a95c699d8..466b9c7a3c2 100644
--- a/compiler/rustc_middle/src/mir/query.rs
+++ b/compiler/rustc_middle/src/mir/query.rs
@@ -149,8 +149,15 @@ pub enum ConstraintCategory<'tcx> {
     /// A constraint that doesn't correspond to anything the user sees.
     Internal,
 
-    /// An internal constraint derived from an illegal universe relation.
-    IllegalUniverse,
+    /// An internal constraint added when a region outlives a placeholder
+    /// it cannot name and therefore has to outlive `'static`. The argument
+    /// is the unnameable placeholder and the constraint is always between
+    /// an SCC representative and `'static`.
+    OutlivesUnnameablePlaceholder(
+        #[type_foldable(identity)]
+        #[type_visitable(ignore)]
+        ty::RegionVid,
+    ),
 }
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
diff --git a/compiler/rustc_middle/src/mir/statement.rs b/compiler/rustc_middle/src/mir/statement.rs
index 683d7b48617..6e52bc775ef 100644
--- a/compiler/rustc_middle/src/mir/statement.rs
+++ b/compiler/rustc_middle/src/mir/statement.rs
@@ -160,7 +160,11 @@ impl<'tcx> PlaceTy<'tcx> {
     /// Convenience wrapper around `projection_ty_core` for `PlaceElem`,
     /// where we can just use the `Ty` that is already stored inline on
     /// field projection elems.
-    pub fn projection_ty(self, tcx: TyCtxt<'tcx>, elem: PlaceElem<'tcx>) -> PlaceTy<'tcx> {
+    pub fn projection_ty<V: ::std::fmt::Debug>(
+        self,
+        tcx: TyCtxt<'tcx>,
+        elem: ProjectionElem<V, Ty<'tcx>>,
+    ) -> PlaceTy<'tcx> {
         self.projection_ty_core(tcx, &elem, |ty| ty, |_, _, _, ty| ty, |ty| ty)
     }
 
@@ -290,6 +294,36 @@ impl<V, T> ProjectionElem<V, T> {
             Self::UnwrapUnsafeBinder(..) => false,
         }
     }
+
+    /// Returns the `ProjectionKind` associated to this projection.
+    pub fn kind(self) -> ProjectionKind {
+        self.try_map(|_| Some(()), |_| ()).unwrap()
+    }
+
+    /// Apply functions to types and values in this projection and return the result.
+    pub fn try_map<V2, T2>(
+        self,
+        v: impl FnOnce(V) -> Option<V2>,
+        t: impl FnOnce(T) -> T2,
+    ) -> Option<ProjectionElem<V2, T2>> {
+        Some(match self {
+            ProjectionElem::Deref => ProjectionElem::Deref,
+            ProjectionElem::Downcast(name, read_variant) => {
+                ProjectionElem::Downcast(name, read_variant)
+            }
+            ProjectionElem::Field(f, ty) => ProjectionElem::Field(f, t(ty)),
+            ProjectionElem::ConstantIndex { offset, min_length, from_end } => {
+                ProjectionElem::ConstantIndex { offset, min_length, from_end }
+            }
+            ProjectionElem::Subslice { from, to, from_end } => {
+                ProjectionElem::Subslice { from, to, from_end }
+            }
+            ProjectionElem::OpaqueCast(ty) => ProjectionElem::OpaqueCast(t(ty)),
+            ProjectionElem::Subtype(ty) => ProjectionElem::Subtype(t(ty)),
+            ProjectionElem::UnwrapUnsafeBinder(ty) => ProjectionElem::UnwrapUnsafeBinder(t(ty)),
+            ProjectionElem::Index(val) => ProjectionElem::Index(v(val)?),
+        })
+    }
 }
 
 /// Alias for projections as they appear in `UserTypeProjection`, where we
diff --git a/compiler/rustc_middle/src/mir/syntax.rs b/compiler/rustc_middle/src/mir/syntax.rs
index 6039a03aa29..3b8def67f92 100644
--- a/compiler/rustc_middle/src/mir/syntax.rs
+++ b/compiler/rustc_middle/src/mir/syntax.rs
@@ -1371,12 +1371,7 @@ pub enum Rvalue<'tcx> {
 
     /// Creates an array where each element is the value of the operand.
     ///
-    /// This is the cause of a bug in the case where the repetition count is zero because the value
-    /// is not dropped, see [#74836].
-    ///
     /// Corresponds to source code like `[x; 32]`.
-    ///
-    /// [#74836]: https://github.com/rust-lang/rust/issues/74836
     Repeat(Operand<'tcx>, ty::Const<'tcx>),
 
     /// Creates a reference of the indicated kind to the place.
diff --git a/compiler/rustc_middle/src/mir/visit.rs b/compiler/rustc_middle/src/mir/visit.rs
index 42a68b29ec7..904d78d69b6 100644
--- a/compiler/rustc_middle/src/mir/visit.rs
+++ b/compiler/rustc_middle/src/mir/visit.rs
@@ -531,13 +531,20 @@ macro_rules! make_mir_visitor {
                         unwind: _,
                         replace: _,
                         drop: _,
-                        async_fut: _,
+                        async_fut,
                     } => {
                         self.visit_place(
                             place,
                             PlaceContext::MutatingUse(MutatingUseContext::Drop),
                             location
                         );
+                        if let Some(async_fut) = async_fut {
+                            self.visit_local(
+                                $(&$mutability)? *async_fut,
+                                PlaceContext::MutatingUse(MutatingUseContext::Borrow),
+                                location
+                            );
+                        }
                     }
 
                     TerminatorKind::Call {
diff --git a/compiler/rustc_middle/src/query/erase.rs b/compiler/rustc_middle/src/query/erase.rs
index a8b357bf105..ea62461ebeb 100644
--- a/compiler/rustc_middle/src/query/erase.rs
+++ b/compiler/rustc_middle/src/query/erase.rs
@@ -343,6 +343,7 @@ trivial! {
     rustc_span::Symbol,
     rustc_span::Ident,
     rustc_target::spec::PanicStrategy,
+    rustc_target::spec::SanitizerSet,
     rustc_type_ir::Variance,
     u32,
     usize,
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index f4d0120a2e7..7bd8a0525a2 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -100,7 +100,7 @@ use rustc_session::lint::LintExpectationId;
 use rustc_span::def_id::LOCAL_CRATE;
 use rustc_span::source_map::Spanned;
 use rustc_span::{DUMMY_SP, Span, Symbol};
-use rustc_target::spec::PanicStrategy;
+use rustc_target::spec::{PanicStrategy, SanitizerSet};
 use {rustc_abi as abi, rustc_ast as ast, rustc_hir as hir};
 
 use crate::infer::canonical::{self, Canonical};
@@ -696,6 +696,22 @@ rustc_queries! {
         return_result_from_ensure_ok
     }
 
+    /// Used in case `mir_borrowck` fails to prove an obligation. We generally assume that
+    /// all goals we prove in MIR type check hold as we've already checked them in HIR typeck.
+    ///
+    /// However, we replace each free region in the MIR body with a unique region inference
+    /// variable. As we may rely on structural identity when proving goals this may cause a
+    /// goal to no longer hold. We store obligations for which this may happen during HIR
+    /// typeck in the `TypeckResults`. We then uniquify and reprove them in case MIR typeck
+    /// encounters an unexpected error. We expect this to result in an error when used and
+    /// delay a bug if it does not.
+    query check_potentially_region_dependent_goals(key: LocalDefId) -> Result<(), ErrorGuaranteed> {
+        desc {
+            |tcx| "reproving potentially region dependent HIR typeck goals for `{}",
+            tcx.def_path_str(key)
+        }
+    }
+
     /// MIR after our optimization passes have run. This is MIR that is ready
     /// for codegen. This is also the only query that can fetch non-local MIR, at present.
     query optimized_mir(key: DefId) -> &'tcx mir::Body<'tcx> {
@@ -1116,6 +1132,11 @@ rustc_queries! {
     }
 
     /// Unsafety-check this `LocalDefId`.
+    query check_transmutes(key: LocalDefId) {
+        desc { |tcx| "check transmute calls inside `{}`", tcx.def_path_str(key) }
+    }
+
+    /// Unsafety-check this `LocalDefId`.
     query check_unsafety(key: LocalDefId) {
         desc { |tcx| "unsafety-checking `{}`", tcx.def_path_str(key) }
     }
@@ -2686,6 +2707,16 @@ rustc_queries! {
         desc { |tcx| "looking up anon const kind of `{}`", tcx.def_path_str(def_id) }
         separate_provide_extern
     }
+
+    /// Checks for the nearest `#[sanitize(xyz = "off")]` or
+    /// `#[sanitize(xyz = "on")]` on this def and any enclosing defs, up to the
+    /// crate root.
+    ///
+    /// Returns the set of sanitizers that is explicitly disabled for this def.
+    query disabled_sanitizers_for(key: LocalDefId) -> SanitizerSet {
+        desc { |tcx| "checking what set of sanitizers are enabled on `{}`", tcx.def_path_str(key) }
+        feedable
+    }
 }
 
 rustc_with_all_queries! { define_callbacks! }
diff --git a/compiler/rustc_middle/src/query/on_disk_cache.rs b/compiler/rustc_middle/src/query/on_disk_cache.rs
index a7ac3442898..546791135ba 100644
--- a/compiler/rustc_middle/src/query/on_disk_cache.rs
+++ b/compiler/rustc_middle/src/query/on_disk_cache.rs
@@ -645,34 +645,29 @@ impl<'a, 'tcx> SpanDecoder for CacheDecoder<'a, 'tcx> {
         let parent = Option::<LocalDefId>::decode(self);
         let tag: u8 = Decodable::decode(self);
 
-        if tag == TAG_PARTIAL_SPAN {
-            return Span::new(BytePos(0), BytePos(0), ctxt, parent);
-        } else if tag == TAG_RELATIVE_SPAN {
-            let dlo = u32::decode(self);
-            let dto = u32::decode(self);
-
-            let enclosing = self.tcx.source_span_untracked(parent.unwrap()).data_untracked();
-            let span = Span::new(
-                enclosing.lo + BytePos::from_u32(dlo),
-                enclosing.lo + BytePos::from_u32(dto),
-                ctxt,
-                parent,
-            );
-
-            return span;
-        } else {
-            debug_assert_eq!(tag, TAG_FULL_SPAN);
-        }
-
-        let file_lo_index = SourceFileIndex::decode(self);
-        let line_lo = usize::decode(self);
-        let col_lo = RelativeBytePos::decode(self);
-        let len = BytePos::decode(self);
-
-        let file_lo = self.file_index_to_file(file_lo_index);
-        let lo = file_lo.lines()[line_lo - 1] + col_lo;
-        let lo = file_lo.absolute_position(lo);
-        let hi = lo + len;
+        let (lo, hi) = match tag {
+            TAG_PARTIAL_SPAN => (BytePos(0), BytePos(0)),
+            TAG_RELATIVE_SPAN => {
+                let dlo = u32::decode(self);
+                let dto = u32::decode(self);
+
+                let enclosing = self.tcx.source_span_untracked(parent.unwrap()).data_untracked();
+                (enclosing.lo + BytePos::from_u32(dlo), enclosing.lo + BytePos::from_u32(dto))
+            }
+            TAG_FULL_SPAN => {
+                let file_lo_index = SourceFileIndex::decode(self);
+                let line_lo = usize::decode(self);
+                let col_lo = RelativeBytePos::decode(self);
+                let len = BytePos::decode(self);
+
+                let file_lo = self.file_index_to_file(file_lo_index);
+                let lo = file_lo.lines()[line_lo - 1] + col_lo;
+                let lo = file_lo.absolute_position(lo);
+                let hi = lo + len;
+                (lo, hi)
+            }
+            _ => unreachable!(),
+        };
 
         Span::new(lo, hi, ctxt, parent)
     }
diff --git a/compiler/rustc_middle/src/thir.rs b/compiler/rustc_middle/src/thir.rs
index 3dd6d2c8928..f1d19800a78 100644
--- a/compiler/rustc_middle/src/thir.rs
+++ b/compiler/rustc_middle/src/thir.rs
@@ -832,17 +832,17 @@ pub enum PatKind<'tcx> {
     },
 
     /// One of the following:
-    /// * `&str` (represented as a valtree), which will be handled as a string pattern and thus
+    /// * `&str`, which will be handled as a string pattern and thus
     ///   exhaustiveness checking will detect if you use the same string twice in different
     ///   patterns.
-    /// * integer, bool, char or float (represented as a valtree), which will be handled by
+    /// * integer, bool, char or float, which will be handled by
     ///   exhaustiveness to cover exactly its own value, similar to `&str`, but these values are
     ///   much simpler.
     /// * raw pointers derived from integers, other raw pointers will have already resulted in an
     //    error.
     /// * `String`, if `string_deref_patterns` is enabled.
     Constant {
-        value: mir::Const<'tcx>,
+        value: ty::Value<'tcx>,
     },
 
     /// Pattern obtained by converting a constant (inline or named) to its pattern
@@ -935,7 +935,7 @@ impl<'tcx> PatRange<'tcx> {
         let lo_is_min = match self.lo {
             PatRangeBoundary::NegInfinity => true,
             PatRangeBoundary::Finite(value) => {
-                let lo = value.try_to_bits(size).unwrap() ^ bias;
+                let lo = value.try_to_scalar_int().unwrap().to_bits(size) ^ bias;
                 lo <= min
             }
             PatRangeBoundary::PosInfinity => false,
@@ -944,7 +944,7 @@ impl<'tcx> PatRange<'tcx> {
             let hi_is_max = match self.hi {
                 PatRangeBoundary::NegInfinity => false,
                 PatRangeBoundary::Finite(value) => {
-                    let hi = value.try_to_bits(size).unwrap() ^ bias;
+                    let hi = value.try_to_scalar_int().unwrap().to_bits(size) ^ bias;
                     hi > max || hi == max && self.end == RangeEnd::Included
                 }
                 PatRangeBoundary::PosInfinity => true,
@@ -957,22 +957,17 @@ impl<'tcx> PatRange<'tcx> {
     }
 
     #[inline]
-    pub fn contains(
-        &self,
-        value: mir::Const<'tcx>,
-        tcx: TyCtxt<'tcx>,
-        typing_env: ty::TypingEnv<'tcx>,
-    ) -> Option<bool> {
+    pub fn contains(&self, value: ty::Value<'tcx>, tcx: TyCtxt<'tcx>) -> Option<bool> {
         use Ordering::*;
-        debug_assert_eq!(self.ty, value.ty());
+        debug_assert_eq!(value.ty, self.ty);
         let ty = self.ty;
-        let value = PatRangeBoundary::Finite(value);
+        let value = PatRangeBoundary::Finite(value.valtree);
         // For performance, it's important to only do the second comparison if necessary.
         Some(
-            match self.lo.compare_with(value, ty, tcx, typing_env)? {
+            match self.lo.compare_with(value, ty, tcx)? {
                 Less | Equal => true,
                 Greater => false,
-            } && match value.compare_with(self.hi, ty, tcx, typing_env)? {
+            } && match value.compare_with(self.hi, ty, tcx)? {
                 Less => true,
                 Equal => self.end == RangeEnd::Included,
                 Greater => false,
@@ -981,21 +976,16 @@ impl<'tcx> PatRange<'tcx> {
     }
 
     #[inline]
-    pub fn overlaps(
-        &self,
-        other: &Self,
-        tcx: TyCtxt<'tcx>,
-        typing_env: ty::TypingEnv<'tcx>,
-    ) -> Option<bool> {
+    pub fn overlaps(&self, other: &Self, tcx: TyCtxt<'tcx>) -> Option<bool> {
         use Ordering::*;
         debug_assert_eq!(self.ty, other.ty);
         // For performance, it's important to only do the second comparison if necessary.
         Some(
-            match other.lo.compare_with(self.hi, self.ty, tcx, typing_env)? {
+            match other.lo.compare_with(self.hi, self.ty, tcx)? {
                 Less => true,
                 Equal => self.end == RangeEnd::Included,
                 Greater => false,
-            } && match self.lo.compare_with(other.hi, self.ty, tcx, typing_env)? {
+            } && match self.lo.compare_with(other.hi, self.ty, tcx)? {
                 Less => true,
                 Equal => other.end == RangeEnd::Included,
                 Greater => false,
@@ -1006,11 +996,13 @@ impl<'tcx> PatRange<'tcx> {
 
 impl<'tcx> fmt::Display for PatRange<'tcx> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        if let PatRangeBoundary::Finite(value) = &self.lo {
+        if let &PatRangeBoundary::Finite(valtree) = &self.lo {
+            let value = ty::Value { ty: self.ty, valtree };
             write!(f, "{value}")?;
         }
-        if let PatRangeBoundary::Finite(value) = &self.hi {
+        if let &PatRangeBoundary::Finite(valtree) = &self.hi {
             write!(f, "{}", self.end)?;
+            let value = ty::Value { ty: self.ty, valtree };
             write!(f, "{value}")?;
         } else {
             // `0..` is parsed as an inclusive range, we must display it correctly.
@@ -1024,7 +1016,8 @@ impl<'tcx> fmt::Display for PatRange<'tcx> {
 /// If present, the const must be of a numeric type.
 #[derive(Copy, Clone, Debug, PartialEq, HashStable, TypeVisitable)]
 pub enum PatRangeBoundary<'tcx> {
-    Finite(mir::Const<'tcx>),
+    /// The type of this valtree is stored in the surrounding `PatRange`.
+    Finite(ty::ValTree<'tcx>),
     NegInfinity,
     PosInfinity,
 }
@@ -1035,20 +1028,15 @@ impl<'tcx> PatRangeBoundary<'tcx> {
         matches!(self, Self::Finite(..))
     }
     #[inline]
-    pub fn as_finite(self) -> Option<mir::Const<'tcx>> {
+    pub fn as_finite(self) -> Option<ty::ValTree<'tcx>> {
         match self {
             Self::Finite(value) => Some(value),
             Self::NegInfinity | Self::PosInfinity => None,
         }
     }
-    pub fn eval_bits(
-        self,
-        ty: Ty<'tcx>,
-        tcx: TyCtxt<'tcx>,
-        typing_env: ty::TypingEnv<'tcx>,
-    ) -> u128 {
+    pub fn to_bits(self, ty: Ty<'tcx>, tcx: TyCtxt<'tcx>) -> u128 {
         match self {
-            Self::Finite(value) => value.eval_bits(tcx, typing_env),
+            Self::Finite(value) => value.try_to_scalar_int().unwrap().to_bits_unchecked(),
             Self::NegInfinity => {
                 // Unwrap is ok because the type is known to be numeric.
                 ty.numeric_min_and_max_as_bits(tcx).unwrap().0
@@ -1060,14 +1048,8 @@ impl<'tcx> PatRangeBoundary<'tcx> {
         }
     }
 
-    #[instrument(skip(tcx, typing_env), level = "debug", ret)]
-    pub fn compare_with(
-        self,
-        other: Self,
-        ty: Ty<'tcx>,
-        tcx: TyCtxt<'tcx>,
-        typing_env: ty::TypingEnv<'tcx>,
-    ) -> Option<Ordering> {
+    #[instrument(skip(tcx), level = "debug", ret)]
+    pub fn compare_with(self, other: Self, ty: Ty<'tcx>, tcx: TyCtxt<'tcx>) -> Option<Ordering> {
         use PatRangeBoundary::*;
         match (self, other) {
             // When comparing with infinities, we must remember that `0u8..` and `0u8..=255`
@@ -1095,8 +1077,8 @@ impl<'tcx> PatRangeBoundary<'tcx> {
             _ => {}
         }
 
-        let a = self.eval_bits(ty, tcx, typing_env);
-        let b = other.eval_bits(ty, tcx, typing_env);
+        let a = self.to_bits(ty, tcx);
+        let b = other.to_bits(ty, tcx);
 
         match ty.kind() {
             ty::Float(ty::FloatTy::F16) => {
diff --git a/compiler/rustc_middle/src/traits/mod.rs b/compiler/rustc_middle/src/traits/mod.rs
index 5bdde3a514e..32f91bfba6b 100644
--- a/compiler/rustc_middle/src/traits/mod.rs
+++ b/compiler/rustc_middle/src/traits/mod.rs
@@ -760,6 +760,9 @@ pub enum DynCompatibilityViolation {
     // Supertrait has a non-lifetime `for<T>` binder.
     SupertraitNonLifetimeBinder(SmallVec<[Span; 1]>),
 
+    // Trait has a `const Trait` supertrait.
+    SupertraitConst(SmallVec<[Span; 1]>),
+
     /// Method has something illegal.
     Method(Symbol, MethodViolationCode, Span),
 
@@ -785,6 +788,9 @@ impl DynCompatibilityViolation {
             DynCompatibilityViolation::SupertraitNonLifetimeBinder(_) => {
                 "where clause cannot reference non-lifetime `for<...>` variables".into()
             }
+            DynCompatibilityViolation::SupertraitConst(_) => {
+                "it cannot have a `const` supertrait".into()
+            }
             DynCompatibilityViolation::Method(name, MethodViolationCode::StaticMethod(_), _) => {
                 format!("associated function `{name}` has no `self` parameter").into()
             }
@@ -842,7 +848,8 @@ impl DynCompatibilityViolation {
         match self {
             DynCompatibilityViolation::SizedSelf(_)
             | DynCompatibilityViolation::SupertraitSelf(_)
-            | DynCompatibilityViolation::SupertraitNonLifetimeBinder(..) => {
+            | DynCompatibilityViolation::SupertraitNonLifetimeBinder(..)
+            | DynCompatibilityViolation::SupertraitConst(_) => {
                 DynCompatibilityViolationSolution::None
             }
             DynCompatibilityViolation::Method(
@@ -873,15 +880,17 @@ impl DynCompatibilityViolation {
         match self {
             DynCompatibilityViolation::SupertraitSelf(spans)
             | DynCompatibilityViolation::SizedSelf(spans)
-            | DynCompatibilityViolation::SupertraitNonLifetimeBinder(spans) => spans.clone(),
+            | DynCompatibilityViolation::SupertraitNonLifetimeBinder(spans)
+            | DynCompatibilityViolation::SupertraitConst(spans) => spans.clone(),
             DynCompatibilityViolation::AssocConst(_, span)
             | DynCompatibilityViolation::GAT(_, span)
-            | DynCompatibilityViolation::Method(_, _, span)
-                if *span != DUMMY_SP =>
-            {
-                smallvec![*span]
+            | DynCompatibilityViolation::Method(_, _, span) => {
+                if *span != DUMMY_SP {
+                    smallvec![*span]
+                } else {
+                    smallvec![]
+                }
             }
-            _ => smallvec![],
         }
     }
 }
diff --git a/compiler/rustc_middle/src/ty/consts/valtree.rs b/compiler/rustc_middle/src/ty/consts/valtree.rs
index d95006dcf4a..a14e47d7082 100644
--- a/compiler/rustc_middle/src/ty/consts/valtree.rs
+++ b/compiler/rustc_middle/src/ty/consts/valtree.rs
@@ -2,10 +2,12 @@ use std::fmt;
 use std::ops::Deref;
 
 use rustc_data_structures::intern::Interned;
+use rustc_hir::def::Namespace;
 use rustc_macros::{HashStable, Lift, TyDecodable, TyEncodable, TypeFoldable, TypeVisitable};
 
 use super::ScalarInt;
 use crate::mir::interpret::{ErrorHandled, Scalar};
+use crate::ty::print::{FmtPrinter, PrettyPrinter};
 use crate::ty::{self, Ty, TyCtxt};
 
 /// This datastructure is used to represent the value of constants used in the type system.
@@ -133,6 +135,8 @@ pub type ConstToValTreeResult<'tcx> = Result<Result<ValTree<'tcx>, Ty<'tcx>>, Er
 /// A type-level constant value.
 ///
 /// Represents a typed, fully evaluated constant.
+/// Note that this is also used by pattern elaboration to represent values which cannot occur in types,
+/// such as raw pointers and floats.
 #[derive(Copy, Clone, Debug, Hash, Eq, PartialEq)]
 #[derive(HashStable, TyEncodable, TyDecodable, TypeFoldable, TypeVisitable, Lift)]
 pub struct Value<'tcx> {
@@ -203,3 +207,14 @@ impl<'tcx> rustc_type_ir::inherent::ValueConst<TyCtxt<'tcx>> for Value<'tcx> {
         self.valtree
     }
 }
+
+impl<'tcx> fmt::Display for Value<'tcx> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        ty::tls::with(move |tcx| {
+            let cv = tcx.lift(*self).unwrap();
+            let mut p = FmtPrinter::new(tcx, Namespace::ValueNS);
+            p.pretty_print_const_valtree(cv, /*print_ty*/ true)?;
+            f.write_str(&p.into_buffer())
+        })
+    }
+}
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 49a4733de3b..4990a85466e 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -33,7 +33,7 @@ use rustc_errors::{
     Applicability, Diag, DiagCtxtHandle, ErrorGuaranteed, LintDiagnostic, LintEmitter, MultiSpan,
 };
 use rustc_hir::attrs::AttributeKind;
-use rustc_hir::def::{CtorKind, DefKind};
+use rustc_hir::def::{CtorKind, CtorOf, DefKind};
 use rustc_hir::def_id::{CrateNum, DefId, LOCAL_CRATE, LocalDefId};
 use rustc_hir::definitions::{DefPathData, Definitions, DisambiguatorState};
 use rustc_hir::intravisit::VisitorExt;
@@ -445,7 +445,10 @@ impl<'tcx> Interner for TyCtxt<'tcx> {
     }
 
     fn fn_is_const(self, def_id: DefId) -> bool {
-        debug_assert_matches!(self.def_kind(def_id), DefKind::Fn | DefKind::AssocFn);
+        debug_assert_matches!(
+            self.def_kind(def_id),
+            DefKind::Fn | DefKind::AssocFn | DefKind::Ctor(CtorOf::Struct, CtorKind::Fn)
+        );
         self.is_conditionally_const(def_id)
     }
 
@@ -1418,6 +1421,8 @@ pub struct TyCtxt<'tcx> {
 }
 
 impl<'tcx> LintEmitter for TyCtxt<'tcx> {
+    type Id = HirId;
+
     fn emit_node_span_lint(
         self,
         lint: &'static Lint,
diff --git a/compiler/rustc_middle/src/ty/diagnostics.rs b/compiler/rustc_middle/src/ty/diagnostics.rs
index b3042904a29..b9a6f67ab0d 100644
--- a/compiler/rustc_middle/src/ty/diagnostics.rs
+++ b/compiler/rustc_middle/src/ty/diagnostics.rs
@@ -23,7 +23,7 @@ impl IntoDiagArg for Ty<'_> {
     fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> rustc_errors::DiagArgValue {
         ty::tls::with(|tcx| {
             let ty = tcx.short_string(self, path);
-            rustc_errors::DiagArgValue::Str(std::borrow::Cow::Owned(ty))
+            DiagArgValue::Str(std::borrow::Cow::Owned(ty))
         })
     }
 }
@@ -32,7 +32,7 @@ impl IntoDiagArg for Instance<'_> {
     fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> rustc_errors::DiagArgValue {
         ty::tls::with(|tcx| {
             let instance = tcx.short_string_namespace(self, path, Namespace::ValueNS);
-            rustc_errors::DiagArgValue::Str(std::borrow::Cow::Owned(instance))
+            DiagArgValue::Str(std::borrow::Cow::Owned(instance))
         })
     }
 }
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 73e1661106e..e567ba05f61 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -32,7 +32,7 @@ use rustc_data_structures::intern::Interned;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::steal::Steal;
 use rustc_data_structures::unord::{UnordMap, UnordSet};
-use rustc_errors::{Diag, ErrorGuaranteed};
+use rustc_errors::{Diag, ErrorGuaranteed, LintBuffer};
 use rustc_hir::attrs::{AttributeKind, StrippedCfgItem};
 use rustc_hir::def::{CtorKind, CtorOf, DefKind, DocLinkResMap, LifetimeRes, Res};
 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, LocalDefIdMap};
@@ -46,7 +46,6 @@ use rustc_macros::{
 };
 use rustc_query_system::ich::StableHashingContext;
 use rustc_serialize::{Decodable, Encodable};
-use rustc_session::lint::LintBuffer;
 pub use rustc_session::lint::RegisteredTools;
 use rustc_span::hygiene::MacroKind;
 use rustc_span::{DUMMY_SP, ExpnId, ExpnKind, Ident, Span, Symbol, sym};
@@ -830,14 +829,15 @@ impl<'tcx> OpaqueHiddenType<'tcx> {
         // Convert the type from the function into a type valid outside by mapping generic
         // parameters to into the context of the opaque.
         //
-        // We erase regions when doing this during HIR typeck.
+        // We erase regions when doing this during HIR typeck. We manually use `fold_regions`
+        // here as we do not want to anonymize bound variables.
         let this = match defining_scope_kind {
-            DefiningScopeKind::HirTypeck => tcx.erase_regions(self),
+            DefiningScopeKind::HirTypeck => fold_regions(tcx, self, |_, _| tcx.lifetimes.re_erased),
             DefiningScopeKind::MirBorrowck => self,
         };
         let result = this.fold_with(&mut opaque_types::ReverseMapper::new(tcx, map, self.span));
         if cfg!(debug_assertions) && matches!(defining_scope_kind, DefiningScopeKind::HirTypeck) {
-            assert_eq!(result.ty, tcx.erase_regions(result.ty));
+            assert_eq!(result.ty, fold_regions(tcx, result.ty, |_, _| tcx.lifetimes.re_erased));
         }
         result
     }
@@ -1925,21 +1925,50 @@ impl<'tcx> TyCtxt<'tcx> {
         self.impl_trait_ref(def_id).map(|tr| tr.skip_binder().def_id)
     }
 
-    /// If the given `DefId` is an associated item, returns the `DefId` of the parent trait or impl.
-    pub fn assoc_parent(self, def_id: DefId) -> Option<DefId> {
-        self.def_kind(def_id).is_assoc().then(|| self.parent(def_id))
+    /// If the given `DefId` is an associated item, returns the `DefId` and `DefKind` of the parent trait or impl.
+    pub fn assoc_parent(self, def_id: DefId) -> Option<(DefId, DefKind)> {
+        if !self.def_kind(def_id).is_assoc() {
+            return None;
+        }
+        let parent = self.parent(def_id);
+        let def_kind = self.def_kind(parent);
+        Some((parent, def_kind))
     }
 
     /// If the given `DefId` is an associated item of a trait,
     /// returns the `DefId` of the trait; otherwise, returns `None`.
     pub fn trait_of_assoc(self, def_id: DefId) -> Option<DefId> {
-        self.assoc_parent(def_id).filter(|id| self.def_kind(id) == DefKind::Trait)
+        match self.assoc_parent(def_id) {
+            Some((id, DefKind::Trait)) => Some(id),
+            _ => None,
+        }
     }
 
     /// If the given `DefId` is an associated item of an impl,
     /// returns the `DefId` of the impl; otherwise returns `None`.
     pub fn impl_of_assoc(self, def_id: DefId) -> Option<DefId> {
-        self.assoc_parent(def_id).filter(|id| matches!(self.def_kind(id), DefKind::Impl { .. }))
+        match self.assoc_parent(def_id) {
+            Some((id, DefKind::Impl { .. })) => Some(id),
+            _ => None,
+        }
+    }
+
+    /// If the given `DefId` is an associated item of an inherent impl,
+    /// returns the `DefId` of the impl; otherwise, returns `None`.
+    pub fn inherent_impl_of_assoc(self, def_id: DefId) -> Option<DefId> {
+        match self.assoc_parent(def_id) {
+            Some((id, DefKind::Impl { of_trait: false })) => Some(id),
+            _ => None,
+        }
+    }
+
+    /// If the given `DefId` is an associated item of a trait impl,
+    /// returns the `DefId` of the impl; otherwise, returns `None`.
+    pub fn trait_impl_of_assoc(self, def_id: DefId) -> Option<DefId> {
+        match self.assoc_parent(def_id) {
+            Some((id, DefKind::Impl { of_trait: true })) => Some(id),
+            _ => None,
+        }
     }
 
     pub fn is_exportable(self, def_id: DefId) -> bool {
diff --git a/compiler/rustc_middle/src/ty/print/mod.rs b/compiler/rustc_middle/src/ty/print/mod.rs
index efa017074db..9e6f277ef77 100644
--- a/compiler/rustc_middle/src/ty/print/mod.rs
+++ b/compiler/rustc_middle/src/ty/print/mod.rs
@@ -19,18 +19,16 @@ pub trait Print<'tcx, P> {
     fn print(&self, p: &mut P) -> Result<(), PrintError>;
 }
 
-/// Interface for outputting user-facing "type-system entities"
-/// (paths, types, lifetimes, constants, etc.) as a side-effect
-/// (e.g. formatting, like `PrettyPrinter` implementors do) or by
-/// constructing some alternative representation (e.g. an AST),
-/// which the associated types allow passing through the methods.
-///
-/// For pretty-printing/formatting in particular, see `PrettyPrinter`.
-//
-// FIXME(eddyb) find a better name; this is more general than "printing".
+/// A trait that "prints" user-facing type system entities: paths, types, lifetimes, constants,
+/// etc. "Printing" here means building up a representation of the entity's path, usually as a
+/// `String` (e.g. "std::io::Read") or a `Vec<Symbol>` (e.g. `[sym::std, sym::io, sym::Read]`). The
+/// representation is built up by appending one or more pieces. The specific details included in
+/// the built-up representation depend on the purpose of the printer. The more advanced printers
+/// also rely on the `PrettyPrinter` sub-trait.
 pub trait Printer<'tcx>: Sized {
     fn tcx<'a>(&'a self) -> TyCtxt<'tcx>;
 
+    /// Appends a representation of an entity with a normal path, e.g. "std::io::Read".
     fn print_def_path(
         &mut self,
         def_id: DefId,
@@ -39,6 +37,7 @@ pub trait Printer<'tcx>: Sized {
         self.default_print_def_path(def_id, args)
     }
 
+    /// Like `print_def_path`, but for `DefPathData::Impl`.
     fn print_impl_path(
         &mut self,
         impl_def_id: DefId,
@@ -64,46 +63,74 @@ pub trait Printer<'tcx>: Sized {
         self.default_print_impl_path(impl_def_id, self_ty, impl_trait_ref)
     }
 
+    /// Appends a representation of a region.
     fn print_region(&mut self, region: ty::Region<'tcx>) -> Result<(), PrintError>;
 
+    /// Appends a representation of a type.
     fn print_type(&mut self, ty: Ty<'tcx>) -> Result<(), PrintError>;
 
+    /// Appends a representation of a list of `PolyExistentialPredicate`s.
     fn print_dyn_existential(
         &mut self,
         predicates: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
     ) -> Result<(), PrintError>;
 
+    /// Appends a representation of a const.
     fn print_const(&mut self, ct: ty::Const<'tcx>) -> Result<(), PrintError>;
 
-    fn path_crate(&mut self, cnum: CrateNum) -> Result<(), PrintError>;
+    /// Appends a representation of a crate name, e.g. `std`, or even ``.
+    fn print_crate_name(&mut self, cnum: CrateNum) -> Result<(), PrintError>;
 
-    fn path_qualified(
+    /// Appends a representation of a (full or partial) simple path, in two parts. `print_prefix`,
+    /// when called, appends the representation of the leading segments. The rest of the method
+    /// appends the representation of the final segment, the details of which are in
+    /// `disambiguated_data`.
+    ///
+    /// E.g. `std::io` + `Read` -> `std::io::Read`.
+    fn print_path_with_simple(
         &mut self,
-        self_ty: Ty<'tcx>,
-        trait_ref: Option<ty::TraitRef<'tcx>>,
+        print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
+        disambiguated_data: &DisambiguatedDefPathData,
     ) -> Result<(), PrintError>;
 
-    fn path_append_impl(
+    /// Similar to `print_path_with_simple`, but the final segment is an `impl` segment.
+    ///
+    /// E.g. `slice` + `<impl [T]>` -> `slice::<impl [T]>`, which may then be further appended to,
+    /// giving a longer path representation such as `slice::<impl [T]>::to_vec_in::ConvertVec`.
+    fn print_path_with_impl(
         &mut self,
         print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
         self_ty: Ty<'tcx>,
         trait_ref: Option<ty::TraitRef<'tcx>>,
     ) -> Result<(), PrintError>;
 
-    fn path_append(
+    /// Appends a representation of a path ending in generic args, in two parts. `print_prefix`,
+    /// when called, appends the leading segments. The rest of the method appends the
+    /// representation of the generic args. (Some printers choose to skip appending the generic
+    /// args.)
+    ///
+    /// E.g. `ImplementsTraitForUsize` + `<usize>` -> `ImplementsTraitForUsize<usize>`.
+    fn print_path_with_generic_args(
         &mut self,
         print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
-        disambiguated_data: &DisambiguatedDefPathData,
+        args: &[GenericArg<'tcx>],
     ) -> Result<(), PrintError>;
 
-    fn path_generic_args(
+    /// Appends a representation of a qualified path segment, e.g. `<OsString as From<&T>>`.
+    /// If `trait_ref` is `None`, it may fall back to simpler forms, e.g. `<Vec<T>>` or just `Foo`.
+    fn print_path_with_qualified(
         &mut self,
-        print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
-        args: &[GenericArg<'tcx>],
+        self_ty: Ty<'tcx>,
+        trait_ref: Option<ty::TraitRef<'tcx>>,
     ) -> Result<(), PrintError>;
 
-    fn should_truncate(&mut self) -> bool {
-        false
+    fn print_coroutine_with_kind(
+        &mut self,
+        def_id: DefId,
+        parent_args: &'tcx [GenericArg<'tcx>],
+        kind: Ty<'tcx>,
+    ) -> Result<(), PrintError> {
+        self.print_path_with_generic_args(|p| p.print_def_path(def_id, parent_args), &[kind.into()])
     }
 
     // Defaults (should not be overridden):
@@ -120,7 +147,7 @@ pub trait Printer<'tcx>: Sized {
         match key.disambiguated_data.data {
             DefPathData::CrateRoot => {
                 assert!(key.parent.is_none());
-                self.path_crate(def_id.krate)
+                self.print_crate_name(def_id.krate)
             }
 
             DefPathData::Impl => self.print_impl_path(def_id, args),
@@ -144,9 +171,10 @@ pub trait Printer<'tcx>: Sized {
                             )) = self.tcx().coroutine_kind(def_id)
                                 && args.len() > parent_args.len()
                             {
-                                return self.path_generic_args(
-                                    |p| p.print_def_path(def_id, parent_args),
-                                    &args[..parent_args.len() + 1][..1],
+                                return self.print_coroutine_with_kind(
+                                    def_id,
+                                    parent_args,
+                                    args[parent_args.len()].expect_ty(),
                                 );
                             } else {
                                 // Closures' own generics are only captures, don't print them.
@@ -166,7 +194,7 @@ pub trait Printer<'tcx>: Sized {
                         _ => {
                             if !generics.is_own_empty() && args.len() >= generics.count() {
                                 let args = generics.own_args_no_defaults(self.tcx(), args);
-                                return self.path_generic_args(
+                                return self.print_path_with_generic_args(
                                     |p| p.print_def_path(def_id, parent_args),
                                     args,
                                 );
@@ -182,7 +210,7 @@ pub trait Printer<'tcx>: Sized {
                         && self.tcx().generics_of(parent_def_id).parent_count == 0;
                 }
 
-                self.path_append(
+                self.print_path_with_simple(
                     |p: &mut Self| {
                         if trait_qualify_parent {
                             let trait_ref = ty::TraitRef::new(
@@ -190,7 +218,7 @@ pub trait Printer<'tcx>: Sized {
                                 parent_def_id,
                                 parent_args.iter().copied(),
                             );
-                            p.path_qualified(trait_ref.self_ty(), Some(trait_ref))
+                            p.print_path_with_qualified(trait_ref.self_ty(), Some(trait_ref))
                         } else {
                             p.print_def_path(parent_def_id, parent_args)
                         }
@@ -233,11 +261,15 @@ pub trait Printer<'tcx>: Sized {
             // If the impl is not co-located with either self-type or
             // trait-type, then fallback to a format that identifies
             // the module more clearly.
-            self.path_append_impl(|p| p.print_def_path(parent_def_id, &[]), self_ty, impl_trait_ref)
+            self.print_path_with_impl(
+                |p| p.print_def_path(parent_def_id, &[]),
+                self_ty,
+                impl_trait_ref,
+            )
         } else {
             // Otherwise, try to give a good form that would be valid language
             // syntax. Preferably using associated item notation.
-            self.path_qualified(self_ty, impl_trait_ref)
+            self.print_path_with_qualified(self_ty, impl_trait_ref)
         }
     }
 }
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index 67244e767cb..74caee7336a 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -245,7 +245,7 @@ impl<'tcx> RegionHighlightMode<'tcx> {
 /// Trait for printers that pretty-print using `fmt::Write` to the printer.
 pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
     /// Like `print_def_path` but for value paths.
-    fn print_value_path(
+    fn pretty_print_value_path(
         &mut self,
         def_id: DefId,
         args: &'tcx [GenericArg<'tcx>],
@@ -253,7 +253,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
         self.print_def_path(def_id, args)
     }
 
-    fn print_in_binder<T>(&mut self, value: &ty::Binder<'tcx, T>) -> Result<(), PrintError>
+    fn pretty_print_in_binder<T>(&mut self, value: &ty::Binder<'tcx, T>) -> Result<(), PrintError>
     where
         T: Print<'tcx, Self> + TypeFoldable<TyCtxt<'tcx>>,
     {
@@ -333,10 +333,14 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
         f: impl FnOnce(&mut Self) -> Result<(), PrintError>,
     ) -> Result<(), PrintError>;
 
-    /// Returns `true` if the region should be printed in
-    /// optional positions, e.g., `&'a T` or `dyn Tr + 'b`.
-    /// This is typically the case for all non-`'_` regions.
-    fn should_print_region(&self, region: ty::Region<'tcx>) -> bool;
+    fn should_truncate(&mut self) -> bool {
+        false
+    }
+
+    /// Returns `true` if the region should be printed in optional positions,
+    /// e.g., `&'a T` or `dyn Tr + 'b`. (Regions like the one in `Cow<'static, T>`
+    /// will always be printed.)
+    fn should_print_optional_region(&self, region: ty::Region<'tcx>) -> bool;
 
     fn reset_type_limit(&mut self) {}
 
@@ -470,7 +474,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
         // path to the crate followed by the path to the item within the crate.
         if let Some(cnum) = def_id.as_crate_root() {
             if cnum == LOCAL_CRATE {
-                self.path_crate(cnum)?;
+                self.print_crate_name(cnum)?;
                 return Ok(true);
             }
 
@@ -494,7 +498,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                         // or avoid ending up with `ExternCrateSource::Extern`,
                         // for the injected `std`/`core`.
                         if span.is_dummy() {
-                            self.path_crate(cnum)?;
+                            self.print_crate_name(cnum)?;
                             return Ok(true);
                         }
 
@@ -508,13 +512,13 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                         return Ok(true);
                     }
                     (ExternCrateSource::Path, LOCAL_CRATE) => {
-                        self.path_crate(cnum)?;
+                        self.print_crate_name(cnum)?;
                         return Ok(true);
                     }
                     _ => {}
                 },
                 None => {
-                    self.path_crate(cnum)?;
+                    self.print_crate_name(cnum)?;
                     return Ok(true);
                 }
             }
@@ -624,7 +628,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
             return Ok(false);
         }
         callers.push(visible_parent);
-        // HACK(eddyb) this bypasses `path_append`'s prefix printing to avoid
+        // HACK(eddyb) this bypasses `print_path_with_simple`'s prefix printing to avoid
         // knowing ahead of time whether the entire path will succeed or not.
         // To support printers that do not implement `PrettyPrinter`, a `Vec` or
         // linked list on the stack would need to be built, before any printing.
@@ -633,11 +637,14 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
             true => {}
         }
         callers.pop();
-        self.path_append(|_| Ok(()), &DisambiguatedDefPathData { data, disambiguator: 0 })?;
+        self.print_path_with_simple(
+            |_| Ok(()),
+            &DisambiguatedDefPathData { data, disambiguator: 0 },
+        )?;
         Ok(true)
     }
 
-    fn pretty_path_qualified(
+    fn pretty_print_path_with_qualified(
         &mut self,
         self_ty: Ty<'tcx>,
         trait_ref: Option<ty::TraitRef<'tcx>>,
@@ -672,7 +679,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
         })
     }
 
-    fn pretty_path_append_impl(
+    fn pretty_print_path_with_impl(
         &mut self,
         print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
         self_ty: Ty<'tcx>,
@@ -710,7 +717,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
             }
             ty::Ref(r, ty, mutbl) => {
                 write!(self, "&")?;
-                if self.should_print_region(r) {
+                if self.should_print_optional_region(r) {
                     r.print(self)?;
                     write!(self, " ")?;
                 }
@@ -739,7 +746,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                     }
                     sig.print(self)?;
                     write!(self, " {{")?;
-                    self.print_value_path(def_id, args)?;
+                    self.pretty_print_value_path(def_id, args)?;
                     write!(self, "}}")?;
                 }
             }
@@ -778,7 +785,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
             },
             ty::Adt(def, args) => self.print_def_path(def.did(), args)?,
             ty::Dynamic(data, r, repr) => {
-                let print_r = self.should_print_region(r);
+                let print_r = self.should_print_optional_region(r);
                 if print_r {
                     write!(self, "(")?;
                 }
@@ -1308,10 +1315,10 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
         alias_ty: ty::AliasTerm<'tcx>,
     ) -> Result<(), PrintError> {
         let def_key = self.tcx().def_key(alias_ty.def_id);
-        self.path_generic_args(
+        self.print_path_with_generic_args(
             |p| {
-                p.path_append(
-                    |p| p.path_qualified(alias_ty.self_ty(), None),
+                p.print_path_with_simple(
+                    |p| p.print_path_with_qualified(alias_ty.self_ty(), None),
                     &def_key.disambiguated_data,
                 )
             },
@@ -1386,7 +1393,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                     if let ty::Tuple(tys) = principal.args.type_at(0).kind() {
                         let mut projections = predicates.projection_bounds();
                         if let (Some(proj), None) = (projections.next(), projections.next()) {
-                            p.pretty_fn_sig(
+                            p.pretty_print_fn_sig(
                                 tys,
                                 false,
                                 proj.skip_binder().term.as_type().expect("Return type was a const"),
@@ -1396,7 +1403,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                     }
                 }
 
-                // HACK(eddyb) this duplicates `FmtPrinter`'s `path_generic_args`,
+                // HACK(eddyb) this duplicates `FmtPrinter`'s `print_path_with_generic_args`,
                 // in order to place the projections inside the `<...>`.
                 if !resugared {
                     let principal_with_self =
@@ -1488,7 +1495,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
         Ok(())
     }
 
-    fn pretty_fn_sig(
+    fn pretty_print_fn_sig(
         &mut self,
         inputs: &[Ty<'tcx>],
         c_variadic: bool,
@@ -1525,7 +1532,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
             ty::ConstKind::Unevaluated(ty::UnevaluatedConst { def, args }) => {
                 match self.tcx().def_kind(def) {
                     DefKind::Const | DefKind::AssocConst => {
-                        self.print_value_path(def, args)?;
+                        self.pretty_print_value_path(def, args)?;
                     }
                     DefKind::AnonConst => {
                         if def.is_local()
@@ -1534,13 +1541,13 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                         {
                             write!(self, "{snip}")?;
                         } else {
-                            // Do not call `print_value_path` as if a parent of this anon const is
-                            // an impl it will attempt to print out the impl trait ref i.e. `<T as
-                            // Trait>::{constant#0}`. This would cause printing to enter an
-                            // infinite recursion if the anon const is in the self type i.e.
-                            // `impl<T: Default> Default for [T; 32 - 1 - 1 - 1] {` where we would
-                            // try to print
-                            // `<[T; /* print constant#0 again */] as // Default>::{constant#0}`.
+                            // Do not call `pretty_print_value_path` as if a parent of this anon
+                            // const is an impl it will attempt to print out the impl trait ref
+                            // i.e. `<T as Trait>::{constant#0}`. This would cause printing to
+                            // enter an infinite recursion if the anon const is in the self type
+                            // i.e. `impl<T: Default> Default for [T; 32 - 1 - 1 - 1] {` where we
+                            // would try to print `<[T; /* print constant#0 again */] as //
+                            // Default>::{constant#0}`.
                             write!(
                                 self,
                                 "{}::{}",
@@ -1742,7 +1749,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                     self.tcx().try_get_global_alloc(prov.alloc_id())
                 {
                     self.typed_value(
-                        |this| this.print_value_path(instance.def_id(), instance.args),
+                        |this| this.pretty_print_value_path(instance.def_id(), instance.args),
                         |this| this.print_type(ty),
                         " as ",
                     )?;
@@ -1936,7 +1943,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                         let variant_idx =
                             contents.variant.expect("destructed const of adt without variant idx");
                         let variant_def = &def.variant(variant_idx);
-                        self.print_value_path(variant_def.def_id, args)?;
+                        self.pretty_print_value_path(variant_def.def_id, args)?;
                         match variant_def.ctor_kind() {
                             Some(CtorKind::Const) => {}
                             Some(CtorKind::Fn) => {
@@ -1972,7 +1979,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
             }
             (_, ty::FnDef(def_id, args)) => {
                 // Never allowed today, but we still encounter them in invalid const args.
-                self.print_value_path(def_id, args)?;
+                self.pretty_print_value_path(def_id, args)?;
                 return Ok(());
             }
             // FIXME(oli-obk): also pretty print arrays and other aggregate constants by reading
@@ -1993,7 +2000,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
         Ok(())
     }
 
-    fn pretty_closure_as_impl(
+    fn pretty_print_closure_as_impl(
         &mut self,
         closure: ty::ClosureArgs<TyCtxt<'tcx>>,
     ) -> Result<(), PrintError> {
@@ -2131,8 +2138,6 @@ impl<'a, 'tcx> FmtPrinter<'a, 'tcx> {
     }
 }
 
-// HACK(eddyb) get rid of `def_path_str` and/or pass `Namespace` explicitly always
-// (but also some things just print a `DefId` generally so maybe we need this?)
 fn guess_def_namespace(tcx: TyCtxt<'_>, def_id: DefId) -> Namespace {
     match tcx.def_key(def_id).disambiguated_data.data {
         DefPathData::TypeNs(..) | DefPathData::CrateRoot | DefPathData::OpaqueTy => {
@@ -2157,6 +2162,7 @@ impl<'t> TyCtxt<'t> {
         self.def_path_str_with_args(def_id, &[])
     }
 
+    /// For this one we determine the appropriate namespace for the `def_id`.
     pub fn def_path_str_with_args(
         self,
         def_id: impl IntoQueryParam<DefId>,
@@ -2169,16 +2175,17 @@ impl<'t> TyCtxt<'t> {
         FmtPrinter::print_string(self, ns, |p| p.print_def_path(def_id, args)).unwrap()
     }
 
+    /// For this one we always use value namespace.
     pub fn value_path_str_with_args(
         self,
         def_id: impl IntoQueryParam<DefId>,
         args: &'t [GenericArg<'t>],
     ) -> String {
         let def_id = def_id.into_query_param();
-        let ns = guess_def_namespace(self, def_id);
+        let ns = Namespace::ValueNS;
         debug!("value_path_str: def_id={:?}, ns={:?}", def_id, ns);
 
-        FmtPrinter::print_string(self, ns, |p| p.print_value_path(def_id, args)).unwrap()
+        FmtPrinter::print_string(self, ns, |p| p.print_def_path(def_id, args)).unwrap()
     }
 }
 
@@ -2230,7 +2237,7 @@ impl<'tcx> Printer<'tcx> for FmtPrinter<'_, 'tcx> {
 
                 self.print_def_path(parent_def_id, &[])?;
 
-                // HACK(eddyb) copy of `path_append` to avoid
+                // HACK(eddyb) copy of `print_path_with_simple` to avoid
                 // constructing a `DisambiguatedDefPathData`.
                 if !self.empty_path {
                     write!(self, "::")?;
@@ -2295,10 +2302,6 @@ impl<'tcx> Printer<'tcx> for FmtPrinter<'_, 'tcx> {
         }
     }
 
-    fn should_truncate(&mut self) -> bool {
-        !self.type_length_limit.value_within_limit(self.printed_type_count)
-    }
-
     fn print_dyn_existential(
         &mut self,
         predicates: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
@@ -2310,7 +2313,7 @@ impl<'tcx> Printer<'tcx> for FmtPrinter<'_, 'tcx> {
         self.pretty_print_const(ct, false)
     }
 
-    fn path_crate(&mut self, cnum: CrateNum) -> Result<(), PrintError> {
+    fn print_crate_name(&mut self, cnum: CrateNum) -> Result<(), PrintError> {
         self.empty_path = true;
         if cnum == LOCAL_CRATE {
             if self.tcx.sess.at_least_rust_2018() {
@@ -2327,23 +2330,23 @@ impl<'tcx> Printer<'tcx> for FmtPrinter<'_, 'tcx> {
         Ok(())
     }
 
-    fn path_qualified(
+    fn print_path_with_qualified(
         &mut self,
         self_ty: Ty<'tcx>,
         trait_ref: Option<ty::TraitRef<'tcx>>,
     ) -> Result<(), PrintError> {
-        self.pretty_path_qualified(self_ty, trait_ref)?;
+        self.pretty_print_path_with_qualified(self_ty, trait_ref)?;
         self.empty_path = false;
         Ok(())
     }
 
-    fn path_append_impl(
+    fn print_path_with_impl(
         &mut self,
         print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
         self_ty: Ty<'tcx>,
         trait_ref: Option<ty::TraitRef<'tcx>>,
     ) -> Result<(), PrintError> {
-        self.pretty_path_append_impl(
+        self.pretty_print_path_with_impl(
             |p| {
                 print_prefix(p)?;
                 if !p.empty_path {
@@ -2359,7 +2362,7 @@ impl<'tcx> Printer<'tcx> for FmtPrinter<'_, 'tcx> {
         Ok(())
     }
 
-    fn path_append(
+    fn print_path_with_simple(
         &mut self,
         print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
         disambiguated_data: &DisambiguatedDefPathData,
@@ -2390,7 +2393,7 @@ impl<'tcx> Printer<'tcx> for FmtPrinter<'_, 'tcx> {
         Ok(())
     }
 
-    fn path_generic_args(
+    fn print_path_with_generic_args(
         &mut self,
         print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
         args: &[GenericArg<'tcx>],
@@ -2421,7 +2424,7 @@ impl<'tcx> PrettyPrinter<'tcx> for FmtPrinter<'_, 'tcx> {
         self.0.const_infer_name_resolver.as_ref().and_then(|func| func(id))
     }
 
-    fn print_value_path(
+    fn pretty_print_value_path(
         &mut self,
         def_id: DefId,
         args: &'tcx [GenericArg<'tcx>],
@@ -2433,7 +2436,7 @@ impl<'tcx> PrettyPrinter<'tcx> for FmtPrinter<'_, 'tcx> {
         Ok(())
     }
 
-    fn print_in_binder<T>(&mut self, value: &ty::Binder<'tcx, T>) -> Result<(), PrintError>
+    fn pretty_print_in_binder<T>(&mut self, value: &ty::Binder<'tcx, T>) -> Result<(), PrintError>
     where
         T: Print<'tcx, Self> + TypeFoldable<TyCtxt<'tcx>>,
     {
@@ -2487,7 +2490,11 @@ impl<'tcx> PrettyPrinter<'tcx> for FmtPrinter<'_, 'tcx> {
         Ok(())
     }
 
-    fn should_print_region(&self, region: ty::Region<'tcx>) -> bool {
+    fn should_truncate(&mut self) -> bool {
+        !self.type_length_limit.value_within_limit(self.printed_type_count)
+    }
+
+    fn should_print_optional_region(&self, region: ty::Region<'tcx>) -> bool {
         let highlight = self.region_highlight_mode;
         if highlight.region_highlighted(region).is_some() {
             return true;
@@ -2892,7 +2899,7 @@ where
     T: Print<'tcx, P> + TypeFoldable<TyCtxt<'tcx>>,
 {
     fn print(&self, p: &mut P) -> Result<(), PrintError> {
-        p.print_in_binder(self)
+        p.pretty_print_in_binder(self)
     }
 }
 
@@ -3090,7 +3097,7 @@ define_print! {
         }
 
         write!(p, "fn")?;
-        p.pretty_fn_sig(self.inputs(), self.c_variadic, self.output())?;
+        p.pretty_print_fn_sig(self.inputs(), self.c_variadic, self.output())?;
     }
 
     ty::TraitRef<'tcx> {
@@ -3225,7 +3232,7 @@ define_print! {
         // The args don't contain the self ty (as it has been erased) but the corresp.
         // generics do as the trait always has a self ty param. We need to offset.
         let args = &self.args[p.tcx().generics_of(self.def_id).parent_count - 1..];
-        p.path_generic_args(|p| write!(p, "{name}"), args)?;
+        p.print_path_with_generic_args(|p| write!(p, "{name}"), args)?;
         write!(p, " = ")?;
         self.term.print(p)?;
     }
@@ -3314,7 +3321,7 @@ define_print_and_forward_display! {
     }
 
     PrintClosureAsImpl<'tcx> {
-        p.pretty_closure_as_impl(self.closure)?;
+        p.pretty_print_closure_as_impl(self.closure)?;
     }
 
     ty::ParamTy {
diff --git a/compiler/rustc_middle/src/ty/structural_impls.rs b/compiler/rustc_middle/src/ty/structural_impls.rs
index 0e2aff6f9bd..89ef46b1ae5 100644
--- a/compiler/rustc_middle/src/ty/structural_impls.rs
+++ b/compiler/rustc_middle/src/ty/structural_impls.rs
@@ -12,7 +12,6 @@ use rustc_hir::def_id::LocalDefId;
 use rustc_span::source_map::Spanned;
 use rustc_type_ir::{ConstKind, TypeFolder, VisitorResult, try_visit};
 
-use super::print::PrettyPrinter;
 use super::{GenericArg, GenericArgKind, Pattern, Region};
 use crate::mir::PlaceElem;
 use crate::ty::print::{FmtPrinter, Printer, with_no_trimmed_paths};
@@ -168,15 +167,11 @@ impl<'tcx> fmt::Debug for ty::Const<'tcx> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         // If this is a value, we spend some effort to make it look nice.
         if let ConstKind::Value(cv) = self.kind() {
-            return ty::tls::with(move |tcx| {
-                let cv = tcx.lift(cv).unwrap();
-                let mut p = FmtPrinter::new(tcx, Namespace::ValueNS);
-                p.pretty_print_const_valtree(cv, /*print_ty*/ true)?;
-                f.write_str(&p.into_buffer())
-            });
+            write!(f, "{}", cv)
+        } else {
+            // Fall back to something verbose.
+            write!(f, "{:?}", self.kind())
         }
-        // Fall back to something verbose.
-        write!(f, "{:?}", self.kind())
     }
 }
 
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index 72474a60566..755fc68d86f 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -821,10 +821,38 @@ impl<'tcx> Ty<'tcx> {
     #[inline]
     pub fn new_coroutine_witness(
         tcx: TyCtxt<'tcx>,
-        id: DefId,
+        def_id: DefId,
         args: GenericArgsRef<'tcx>,
     ) -> Ty<'tcx> {
-        Ty::new(tcx, CoroutineWitness(id, args))
+        if cfg!(debug_assertions) {
+            tcx.debug_assert_args_compatible(tcx.typeck_root_def_id(def_id), args);
+        }
+        Ty::new(tcx, CoroutineWitness(def_id, args))
+    }
+
+    pub fn new_coroutine_witness_for_coroutine(
+        tcx: TyCtxt<'tcx>,
+        def_id: DefId,
+        coroutine_args: GenericArgsRef<'tcx>,
+    ) -> Ty<'tcx> {
+        tcx.debug_assert_args_compatible(def_id, coroutine_args);
+        // HACK: Coroutine witness types are lifetime erased, so they
+        // never reference any lifetime args from the coroutine. We erase
+        // the regions here since we may get into situations where a
+        // coroutine is recursively contained within itself, leading to
+        // witness types that differ by region args. This means that
+        // cycle detection in fulfillment will not kick in, which leads
+        // to unnecessary overflows in async code. See the issue:
+        // <https://github.com/rust-lang/rust/issues/145151>.
+        let args =
+            ty::GenericArgs::for_item(tcx, tcx.typeck_root_def_id(def_id), |def, _| {
+                match def.kind {
+                    ty::GenericParamDefKind::Lifetime => tcx.lifetimes.re_erased.into(),
+                    ty::GenericParamDefKind::Type { .. }
+                    | ty::GenericParamDefKind::Const { .. } => coroutine_args[def.index as usize],
+                }
+            });
+        Ty::new_coroutine_witness(tcx, def_id, args)
     }
 
     // misc
@@ -985,6 +1013,14 @@ impl<'tcx> rustc_type_ir::inherent::Ty<TyCtxt<'tcx>> for Ty<'tcx> {
         Ty::new_coroutine_witness(interner, def_id, args)
     }
 
+    fn new_coroutine_witness_for_coroutine(
+        interner: TyCtxt<'tcx>,
+        def_id: DefId,
+        coroutine_args: ty::GenericArgsRef<'tcx>,
+    ) -> Self {
+        Ty::new_coroutine_witness_for_coroutine(interner, def_id, coroutine_args)
+    }
+
     fn new_ptr(interner: TyCtxt<'tcx>, ty: Self, mutbl: hir::Mutability) -> Self {
         Ty::new_ptr(interner, ty, mutbl)
     }
diff --git a/compiler/rustc_middle/src/ty/trait_def.rs b/compiler/rustc_middle/src/ty/trait_def.rs
index 59e2b2a034d..4e38d969192 100644
--- a/compiler/rustc_middle/src/ty/trait_def.rs
+++ b/compiler/rustc_middle/src/ty/trait_def.rs
@@ -6,6 +6,7 @@ use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
 use rustc_macros::{Decodable, Encodable, HashStable};
+use rustc_span::symbol::sym;
 use tracing::debug;
 
 use crate::query::LocalCrate;
@@ -239,6 +240,12 @@ pub(super) fn trait_impls_of_provider(tcx: TyCtxt<'_>, trait_id: DefId) -> Trait
 
 /// Query provider for `incoherent_impls`.
 pub(super) fn incoherent_impls_provider(tcx: TyCtxt<'_>, simp: SimplifiedType) -> &[DefId] {
+    if let Some(def_id) = simp.def()
+        && !tcx.has_attr(def_id, sym::rustc_has_incoherent_inherent_impls)
+    {
+        return &[];
+    }
+
     let mut impls = Vec::new();
     for cnum in iter::once(LOCAL_CRATE).chain(tcx.crates(()).iter().copied()) {
         for &impl_def_id in tcx.crate_incoherent_impls((cnum, simp)) {
diff --git a/compiler/rustc_middle/src/ty/typeck_results.rs b/compiler/rustc_middle/src/ty/typeck_results.rs
index 6b187c5325a..8dd80aab946 100644
--- a/compiler/rustc_middle/src/ty/typeck_results.rs
+++ b/compiler/rustc_middle/src/ty/typeck_results.rs
@@ -206,10 +206,25 @@ pub struct TypeckResults<'tcx> {
     /// formatting modified file tests/ui/coroutine/retain-resume-ref.rs
     pub coroutine_stalled_predicates: FxIndexSet<(ty::Predicate<'tcx>, ObligationCause<'tcx>)>,
 
+    /// Goals proven during HIR typeck which may be potentially region dependent.
+    ///
+    /// Borrowck *uniquifies* regions which may cause these goal to be ambiguous in MIR
+    /// type check. We ICE if goals fail in borrowck to detect bugs during MIR building or
+    /// missed checks in HIR typeck. To avoid ICE due to region dependence we store all
+    /// goals which may be region dependent and reprove them in case borrowck encounters
+    /// an error.
+    pub potentially_region_dependent_goals:
+        FxIndexSet<(ty::Predicate<'tcx>, ObligationCause<'tcx>)>,
+
     /// Contains the data for evaluating the effect of feature `capture_disjoint_fields`
     /// on closure size.
     pub closure_size_eval: LocalDefIdMap<ClosureSizeProfileData<'tcx>>,
 
+    /// Stores the types involved in calls to `transmute` intrinsic. These are meant to be checked
+    /// outside of typeck and borrowck to avoid cycles with opaque types and coroutine layout
+    /// computation.
+    pub transmutes_to_check: Vec<(Ty<'tcx>, Ty<'tcx>, HirId)>,
+
     /// Container types and field indices of `offset_of!` expressions
     offset_of_data: ItemLocalMap<(Ty<'tcx>, Vec<(VariantIdx, FieldIdx)>)>,
 }
@@ -240,7 +255,9 @@ impl<'tcx> TypeckResults<'tcx> {
             closure_fake_reads: Default::default(),
             rvalue_scopes: Default::default(),
             coroutine_stalled_predicates: Default::default(),
+            potentially_region_dependent_goals: Default::default(),
             closure_size_eval: Default::default(),
+            transmutes_to_check: Default::default(),
             offset_of_data: Default::default(),
         }
     }
diff --git a/compiler/rustc_mir_build/Cargo.toml b/compiler/rustc_mir_build/Cargo.toml
index f756f0a19ee..c3f7fdfcb00 100644
--- a/compiler/rustc_mir_build/Cargo.toml
+++ b/compiler/rustc_mir_build/Cargo.toml
@@ -5,7 +5,7 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-itertools = "0.12"
+itertools.workspace = true
 rustc_abi = { path = "../rustc_abi" }
 rustc_apfloat = "0.2.0"
 rustc_arena = { path = "../rustc_arena" }
@@ -23,5 +23,5 @@ rustc_pattern_analysis = { path = "../rustc_pattern_analysis" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_trait_selection = { path = "../rustc_trait_selection" }
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_mir_build/src/builder/coverageinfo.rs b/compiler/rustc_mir_build/src/builder/coverageinfo.rs
index 14199c20921..091b9dad5bc 100644
--- a/compiler/rustc_mir_build/src/builder/coverageinfo.rs
+++ b/compiler/rustc_mir_build/src/builder/coverageinfo.rs
@@ -157,6 +157,21 @@ impl CoverageInfoBuilder {
         // if there's nothing interesting in it.
         Box::new(CoverageInfoHi { num_block_markers, branch_spans })
     }
+
+    pub(crate) fn as_done(&self) -> Box<CoverageInfoHi> {
+        let &Self { nots: _, markers: BlockMarkerGen { num_block_markers }, ref branch_info } =
+            self;
+
+        let branch_spans = branch_info
+            .as_ref()
+            .map(|branch_info| branch_info.branch_spans.as_slice())
+            .unwrap_or_default()
+            .to_owned();
+
+        // For simplicity, always return an info struct (without Option), even
+        // if there's nothing interesting in it.
+        Box::new(CoverageInfoHi { num_block_markers, branch_spans })
+    }
 }
 
 impl<'tcx> Builder<'_, 'tcx> {
diff --git a/compiler/rustc_mir_build/src/builder/custom/mod.rs b/compiler/rustc_mir_build/src/builder/custom/mod.rs
index 902a6e7f115..792ad6d782c 100644
--- a/compiler/rustc_mir_build/src/builder/custom/mod.rs
+++ b/compiler/rustc_mir_build/src/builder/custom/mod.rs
@@ -19,10 +19,10 @@
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_hir::def_id::DefId;
-use rustc_hir::{Attribute, HirId};
+use rustc_hir::{HirId, attrs};
 use rustc_index::{IndexSlice, IndexVec};
+use rustc_middle::bug;
 use rustc_middle::mir::*;
-use rustc_middle::span_bug;
 use rustc_middle::thir::*;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::Span;
@@ -39,7 +39,8 @@ pub(super) fn build_custom_mir<'tcx>(
     return_ty: Ty<'tcx>,
     return_ty_span: Span,
     span: Span,
-    attr: &Attribute,
+    dialect: Option<attrs::MirDialect>,
+    phase: Option<attrs::MirPhase>,
 ) -> Body<'tcx> {
     let mut body = Body {
         basic_blocks: BasicBlocks::new(IndexVec::new()),
@@ -72,7 +73,7 @@ pub(super) fn build_custom_mir<'tcx>(
         inlined_parent_scope: None,
         local_data: ClearCrossCrate::Set(SourceScopeLocalData { lint_root: hir_id }),
     });
-    body.injection_phase = Some(parse_attribute(attr));
+    body.injection_phase = Some(parse_attribute(dialect, phase));
 
     let mut pctxt = ParseCtxt {
         tcx,
@@ -98,40 +99,38 @@ pub(super) fn build_custom_mir<'tcx>(
     body
 }
 
-fn parse_attribute(attr: &Attribute) -> MirPhase {
-    let meta_items = attr.meta_item_list().unwrap();
-    let mut dialect: Option<String> = None;
-    let mut phase: Option<String> = None;
-
-    // Not handling errors properly for this internal attribute; will just abort on errors.
-    for nested in meta_items {
-        let name = nested.name().unwrap();
-        let value = nested.value_str().unwrap().as_str().to_string();
-        match name.as_str() {
-            "dialect" => {
-                assert!(dialect.is_none());
-                dialect = Some(value);
-            }
-            "phase" => {
-                assert!(phase.is_none());
-                phase = Some(value);
-            }
-            other => {
-                span_bug!(
-                    nested.span(),
-                    "Unexpected key while parsing custom_mir attribute: '{}'",
-                    other
-                );
-            }
-        }
-    }
-
+/// Turns the arguments passed to `#[custom_mir(..)]` into a proper
+/// [`MirPhase`]. Panics if this isn't possible for any reason.
+fn parse_attribute(dialect: Option<attrs::MirDialect>, phase: Option<attrs::MirPhase>) -> MirPhase {
     let Some(dialect) = dialect else {
+        // Caught during attribute checking.
         assert!(phase.is_none());
         return MirPhase::Built;
     };
 
-    MirPhase::parse(dialect, phase)
+    match dialect {
+        attrs::MirDialect::Built => {
+            // Caught during attribute checking.
+            assert!(phase.is_none(), "Cannot specify a phase for `Built` MIR");
+            MirPhase::Built
+        }
+        attrs::MirDialect::Analysis => match phase {
+            None | Some(attrs::MirPhase::Initial) => MirPhase::Analysis(AnalysisPhase::Initial),
+
+            Some(attrs::MirPhase::PostCleanup) => MirPhase::Analysis(AnalysisPhase::PostCleanup),
+
+            Some(attrs::MirPhase::Optimized) => {
+                // Caught during attribute checking.
+                bug!("`optimized` dialect is not compatible with the `analysis` dialect")
+            }
+        },
+
+        attrs::MirDialect::Runtime => match phase {
+            None | Some(attrs::MirPhase::Initial) => MirPhase::Runtime(RuntimePhase::Initial),
+            Some(attrs::MirPhase::PostCleanup) => MirPhase::Runtime(RuntimePhase::PostCleanup),
+            Some(attrs::MirPhase::Optimized) => MirPhase::Runtime(RuntimePhase::Optimized),
+        },
+    }
 }
 
 struct ParseCtxt<'a, 'tcx> {
diff --git a/compiler/rustc_mir_build/src/builder/custom/parse/instruction.rs b/compiler/rustc_mir_build/src/builder/custom/parse/instruction.rs
index 9825b947fe0..41d3aefcbe6 100644
--- a/compiler/rustc_mir_build/src/builder/custom/parse/instruction.rs
+++ b/compiler/rustc_mir_build/src/builder/custom/parse/instruction.rs
@@ -160,7 +160,7 @@ impl<'a, 'tcx> ParseCtxt<'a, 'tcx> {
                     });
                 }
             };
-            values.push(value.eval_bits(self.tcx, self.typing_env));
+            values.push(value.valtree.unwrap_leaf().to_bits_unchecked());
             targets.push(self.parse_block(arm.body)?);
         }
 
diff --git a/compiler/rustc_mir_build/src/builder/matches/mod.rs b/compiler/rustc_mir_build/src/builder/matches/mod.rs
index 94ae5dadd8a..6ee9674bb08 100644
--- a/compiler/rustc_mir_build/src/builder/matches/mod.rs
+++ b/compiler/rustc_mir_build/src/builder/matches/mod.rs
@@ -16,7 +16,7 @@ use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_hir::{BindingMode, ByRef, LetStmt, LocalSource, Node};
 use rustc_middle::bug;
 use rustc_middle::middle::region;
-use rustc_middle::mir::{self, *};
+use rustc_middle::mir::*;
 use rustc_middle::thir::{self, *};
 use rustc_middle::ty::{self, CanonicalUserTypeAnnotation, Ty, ValTree, ValTreeKind};
 use rustc_pattern_analysis::constructor::RangeEnd;
@@ -1245,7 +1245,7 @@ struct Ascription<'tcx> {
 #[derive(Debug, Clone)]
 enum TestCase<'tcx> {
     Variant { adt_def: ty::AdtDef<'tcx>, variant_index: VariantIdx },
-    Constant { value: mir::Const<'tcx> },
+    Constant { value: ty::Value<'tcx> },
     Range(Arc<PatRange<'tcx>>),
     Slice { len: usize, variable_length: bool },
     Deref { temp: Place<'tcx>, mutability: Mutability },
@@ -1316,13 +1316,13 @@ enum TestKind<'tcx> {
     If,
 
     /// Test for equality with value, possibly after an unsizing coercion to
-    /// `ty`,
+    /// `cast_ty`,
     Eq {
-        value: Const<'tcx>,
+        value: ty::Value<'tcx>,
         // Integer types are handled by `SwitchInt`, and constants with ADT
         // types and `&[T]` types are converted back into patterns, so this can
-        // only be `&str`, `f32` or `f64`.
-        ty: Ty<'tcx>,
+        // only be `&str` or floats.
+        cast_ty: Ty<'tcx>,
     },
 
     /// Test whether the value falls within an inclusive or exclusive range.
@@ -1357,8 +1357,8 @@ pub(crate) struct Test<'tcx> {
 enum TestBranch<'tcx> {
     /// Success branch, used for tests with two possible outcomes.
     Success,
-    /// Branch corresponding to this constant.
-    Constant(Const<'tcx>, u128),
+    /// Branch corresponding to this constant. Must be a scalar.
+    Constant(ty::Value<'tcx>),
     /// Branch corresponding to this variant.
     Variant(VariantIdx),
     /// Failure branch for tests with two possible outcomes, and "otherwise" branch for other tests.
@@ -1366,8 +1366,8 @@ enum TestBranch<'tcx> {
 }
 
 impl<'tcx> TestBranch<'tcx> {
-    fn as_constant(&self) -> Option<&Const<'tcx>> {
-        if let Self::Constant(v, _) = self { Some(v) } else { None }
+    fn as_constant(&self) -> Option<ty::Value<'tcx>> {
+        if let Self::Constant(v) = self { Some(*v) } else { None }
     }
 }
 
diff --git a/compiler/rustc_mir_build/src/builder/matches/test.rs b/compiler/rustc_mir_build/src/builder/matches/test.rs
index a4609a6053e..d03794fe2d5 100644
--- a/compiler/rustc_mir_build/src/builder/matches/test.rs
+++ b/compiler/rustc_mir_build/src/builder/matches/test.rs
@@ -35,7 +35,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
             TestCase::Constant { .. } if match_pair.pattern_ty.is_bool() => TestKind::If,
             TestCase::Constant { .. } if is_switch_ty(match_pair.pattern_ty) => TestKind::SwitchInt,
-            TestCase::Constant { value } => TestKind::Eq { value, ty: match_pair.pattern_ty },
+            TestCase::Constant { value } => TestKind::Eq { value, cast_ty: match_pair.pattern_ty },
 
             TestCase::Range(ref range) => {
                 assert_eq!(range.ty, match_pair.pattern_ty);
@@ -112,7 +112,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 let otherwise_block = target_block(TestBranch::Failure);
                 let switch_targets = SwitchTargets::new(
                     target_blocks.iter().filter_map(|(&branch, &block)| {
-                        if let TestBranch::Constant(_, bits) = branch {
+                        if let TestBranch::Constant(value) = branch {
+                            let bits = value.valtree.unwrap_leaf().to_bits_unchecked();
                             Some((bits, block))
                         } else {
                             None
@@ -135,17 +136,17 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 self.cfg.terminate(block, self.source_info(match_start_span), terminator);
             }
 
-            TestKind::Eq { value, mut ty } => {
+            TestKind::Eq { value, mut cast_ty } => {
                 let tcx = self.tcx;
                 let success_block = target_block(TestBranch::Success);
                 let fail_block = target_block(TestBranch::Failure);
 
-                let mut expect_ty = value.ty();
-                let mut expect = self.literal_operand(test.span, value);
+                let mut expect_ty = value.ty;
+                let mut expect = self.literal_operand(test.span, Const::from_ty_value(tcx, value));
 
                 let mut place = place;
                 let mut block = block;
-                match ty.kind() {
+                match cast_ty.kind() {
                     ty::Str => {
                         // String literal patterns may have type `str` if `deref_patterns` is
                         // enabled, in order to allow `deref!("..."): String`. In this case, `value`
@@ -167,7 +168,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                             Rvalue::Ref(re_erased, BorrowKind::Shared, place),
                         );
                         place = ref_place;
-                        ty = ref_str_ty;
+                        cast_ty = ref_str_ty;
                     }
                     ty::Adt(def, _) if tcx.is_lang_item(def.did(), LangItem::String) => {
                         if !tcx.features().string_deref_patterns() {
@@ -186,7 +187,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                             eq_block,
                             place,
                             Mutability::Not,
-                            ty,
+                            cast_ty,
                             ref_str,
                             test.span,
                         );
@@ -195,10 +196,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         // Similarly, the normal test code should be generated for the `&str`, instead of the `String`.
                         block = eq_block;
                         place = ref_str;
-                        ty = ref_str_ty;
+                        cast_ty = ref_str_ty;
                     }
                     &ty::Pat(base, _) => {
-                        assert_eq!(ty, value.ty());
+                        assert_eq!(cast_ty, value.ty);
                         assert!(base.is_trivially_pure_clone_copy());
 
                         let transmuted_place = self.temp(base, test.span);
@@ -219,14 +220,14 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
                         place = transmuted_place;
                         expect = Operand::Copy(transmuted_expect);
-                        ty = base;
+                        cast_ty = base;
                         expect_ty = base;
                     }
                     _ => {}
                 }
 
-                assert_eq!(expect_ty, ty);
-                if !ty.is_scalar() {
+                assert_eq!(expect_ty, cast_ty);
+                if !cast_ty.is_scalar() {
                     // Use `PartialEq::eq` instead of `BinOp::Eq`
                     // (the binop can only handle primitives)
                     // Make sure that we do *not* call any user-defined code here.
@@ -234,10 +235,13 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     // comparison defined in `core`.
                     // (Interestingly this means that exhaustiveness analysis relies, for soundness,
                     // on the `PartialEq` impl for `str` to b correct!)
-                    match *ty.kind() {
+                    match *cast_ty.kind() {
                         ty::Ref(_, deref_ty, _) if deref_ty == self.tcx.types.str_ => {}
                         _ => {
-                            span_bug!(source_info.span, "invalid type for non-scalar compare: {ty}")
+                            span_bug!(
+                                source_info.span,
+                                "invalid type for non-scalar compare: {cast_ty}"
+                            )
                         }
                     };
                     self.string_compare(
@@ -276,7 +280,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 };
 
                 if let Some(lo) = range.lo.as_finite() {
-                    let lo = self.literal_operand(test.span, lo);
+                    let lo = ty::Value { ty: range.ty, valtree: lo };
+                    let lo = self.literal_operand(test.span, Const::from_ty_value(self.tcx, lo));
                     self.compare(
                         block,
                         intermediate_block,
@@ -289,7 +294,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 };
 
                 if let Some(hi) = range.hi.as_finite() {
-                    let hi = self.literal_operand(test.span, hi);
+                    let hi = ty::Value { ty: range.ty, valtree: hi };
+                    let hi = self.literal_operand(test.span, Const::from_ty_value(self.tcx, hi));
                     let op = match range.end {
                         RangeEnd::Included => BinOp::Le,
                         RangeEnd::Excluded => BinOp::Lt,
@@ -555,10 +561,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 // not to add such values here.
                 let is_covering_range = |test_case: &TestCase<'tcx>| {
                     test_case.as_range().is_some_and(|range| {
-                        matches!(
-                            range.contains(value, self.tcx, self.typing_env()),
-                            None | Some(true)
-                        )
+                        matches!(range.contains(value, self.tcx), None | Some(true))
                     })
                 };
                 let is_conflicting_candidate = |candidate: &&mut Candidate<'tcx>| {
@@ -575,8 +578,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     None
                 } else {
                     fully_matched = true;
-                    let bits = value.eval_bits(self.tcx, self.typing_env());
-                    Some(TestBranch::Constant(value, bits))
+                    Some(TestBranch::Constant(value))
                 }
             }
             (TestKind::SwitchInt, TestCase::Range(range)) => {
@@ -585,12 +587,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 // the values being tested. (This restricts what values can be
                 // added to the test by subsequent candidates.)
                 fully_matched = false;
-                let not_contained =
-                    sorted_candidates.keys().filter_map(|br| br.as_constant()).copied().all(
-                        |val| {
-                            matches!(range.contains(val, self.tcx, self.typing_env()), Some(false))
-                        },
-                    );
+                let not_contained = sorted_candidates
+                    .keys()
+                    .filter_map(|br| br.as_constant())
+                    .all(|val| matches!(range.contains(val, self.tcx), Some(false)));
 
                 not_contained.then(|| {
                     // No switch values are contained in the pattern range,
@@ -601,7 +601,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
             (TestKind::If, TestCase::Constant { value }) => {
                 fully_matched = true;
-                let value = value.try_eval_bool(self.tcx, self.typing_env()).unwrap_or_else(|| {
+                let value = value.try_to_bool().unwrap_or_else(|| {
                     span_bug!(test.span, "expected boolean value but got {value:?}")
                 });
                 Some(if value { TestBranch::Success } else { TestBranch::Failure })
@@ -681,16 +681,12 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     fully_matched = false;
                     // If the testing range does not overlap with pattern range,
                     // the pattern can be matched only if this test fails.
-                    if !test.overlaps(pat, self.tcx, self.typing_env())? {
-                        Some(TestBranch::Failure)
-                    } else {
-                        None
-                    }
+                    if !test.overlaps(pat, self.tcx)? { Some(TestBranch::Failure) } else { None }
                 }
             }
             (TestKind::Range(range), &TestCase::Constant { value }) => {
                 fully_matched = false;
-                if !range.contains(value, self.tcx, self.typing_env())? {
+                if !range.contains(value, self.tcx)? {
                     // `value` is not contained in the testing range,
                     // so `value` can be matched only if this test fails.
                     Some(TestBranch::Failure)
diff --git a/compiler/rustc_mir_build/src/builder/mod.rs b/compiler/rustc_mir_build/src/builder/mod.rs
index 855cd2f3bc0..6a8f0b21ee0 100644
--- a/compiler/rustc_mir_build/src/builder/mod.rs
+++ b/compiler/rustc_mir_build/src/builder/mod.rs
@@ -11,9 +11,10 @@ use rustc_ast::attr;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sorted_map::SortedIndexMultiMap;
 use rustc_errors::ErrorGuaranteed;
+use rustc_hir::attrs::AttributeKind;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LocalDefId};
-use rustc_hir::{self as hir, BindingMode, ByRef, HirId, ItemLocalId, Node};
+use rustc_hir::{self as hir, BindingMode, ByRef, HirId, ItemLocalId, Node, find_attr};
 use rustc_index::bit_set::GrowableBitSet;
 use rustc_index::{Idx, IndexSlice, IndexVec};
 use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
@@ -479,8 +480,7 @@ fn construct_fn<'tcx>(
         ty => span_bug!(span_with_body, "unexpected type of body: {ty:?}"),
     };
 
-    if let Some(custom_mir_attr) =
-        tcx.hir_attrs(fn_id).iter().find(|attr| attr.has_name(sym::custom_mir))
+    if let Some((dialect, phase)) = find_attr!(tcx.hir_attrs(fn_id), AttributeKind::CustomMir(dialect, phase, _) => (dialect, phase))
     {
         return custom::build_custom_mir(
             tcx,
@@ -492,7 +492,8 @@ fn construct_fn<'tcx>(
             return_ty,
             return_ty_span,
             span_with_body,
-            custom_mir_attr,
+            dialect.as_ref().map(|(d, _)| *d),
+            phase.as_ref().map(|(p, _)| *p),
         );
     }
 
@@ -789,6 +790,28 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         builder
     }
 
+    #[allow(dead_code)]
+    fn dump_for_debugging(&self) {
+        let mut body = Body::new(
+            MirSource::item(self.def_id.to_def_id()),
+            self.cfg.basic_blocks.clone(),
+            self.source_scopes.clone(),
+            self.local_decls.clone(),
+            self.canonical_user_type_annotations.clone(),
+            self.arg_count.clone(),
+            self.var_debug_info.clone(),
+            self.fn_span.clone(),
+            self.coroutine.clone(),
+            None,
+        );
+        body.coverage_info_hi = self.coverage_info.as_ref().map(|b| b.as_done());
+
+        use rustc_middle::mir::pretty;
+        let options = pretty::PrettyPrintMirOptions::from_cli(self.tcx);
+        pretty::write_mir_fn(self.tcx, &body, &mut |_, _| Ok(()), &mut std::io::stdout(), options)
+            .unwrap();
+    }
+
     fn finish(self) -> Body<'tcx> {
         let mut body = Body::new(
             MirSource::item(self.def_id.to_def_id()),
diff --git a/compiler/rustc_mir_build/src/check_tail_calls.rs b/compiler/rustc_mir_build/src/check_tail_calls.rs
index 3ecccb422c4..e0cbe8519ed 100644
--- a/compiler/rustc_mir_build/src/check_tail_calls.rs
+++ b/compiler/rustc_mir_build/src/check_tail_calls.rs
@@ -3,6 +3,7 @@ use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_errors::Applicability;
 use rustc_hir::LangItem;
 use rustc_hir::def::DefKind;
+use rustc_hir::def_id::CRATE_DEF_ID;
 use rustc_middle::span_bug;
 use rustc_middle::thir::visit::{self, Visitor};
 use rustc_middle::thir::{BodyTy, Expr, ExprId, ExprKind, Thir};
@@ -134,22 +135,23 @@ impl<'tcx> TailCallCkVisitor<'_, 'tcx> {
             self.report_abi_mismatch(expr.span, caller_sig.abi, callee_sig.abi);
         }
 
+        // FIXME(explicit_tail_calls): this currently fails for cases where opaques are used.
+        // e.g.
+        // ```
+        // fn a() -> impl Sized { become b() } // ICE
+        // fn b() -> u8 { 0 }
+        // ```
+        // we should think what is the expected behavior here.
+        // (we should probably just accept this by revealing opaques?)
         if caller_sig.inputs_and_output != callee_sig.inputs_and_output {
-            if caller_sig.inputs() != callee_sig.inputs() {
-                self.report_arguments_mismatch(expr.span, caller_sig, callee_sig);
-            }
-
-            // FIXME(explicit_tail_calls): this currently fails for cases where opaques are used.
-            // e.g.
-            // ```
-            // fn a() -> impl Sized { become b() } // ICE
-            // fn b() -> u8 { 0 }
-            // ```
-            // we should think what is the expected behavior here.
-            // (we should probably just accept this by revealing opaques?)
-            if caller_sig.output() != callee_sig.output() {
-                span_bug!(expr.span, "hir typeck should have checked the return type already");
-            }
+            self.report_signature_mismatch(
+                expr.span,
+                self.tcx.liberate_late_bound_regions(
+                    CRATE_DEF_ID.to_def_id(),
+                    self.caller_ty.fn_sig(self.tcx),
+                ),
+                self.tcx.liberate_late_bound_regions(CRATE_DEF_ID.to_def_id(), ty.fn_sig(self.tcx)),
+            );
         }
 
         {
@@ -356,7 +358,7 @@ impl<'tcx> TailCallCkVisitor<'_, 'tcx> {
         self.found_errors = Err(err);
     }
 
-    fn report_arguments_mismatch(
+    fn report_signature_mismatch(
         &mut self,
         sp: Span,
         caller_sig: ty::FnSig<'_>,
diff --git a/compiler/rustc_mir_build/src/check_unsafety.rs b/compiler/rustc_mir_build/src/check_unsafety.rs
index 0b6b36640e9..b5e165c7517 100644
--- a/compiler/rustc_mir_build/src/check_unsafety.rs
+++ b/compiler/rustc_mir_build/src/check_unsafety.rs
@@ -5,9 +5,10 @@ use std::ops::Bound;
 use rustc_ast::AsmMacro;
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_errors::DiagArgValue;
+use rustc_hir::attrs::AttributeKind;
 use rustc_hir::def::DefKind;
-use rustc_hir::{self as hir, BindingMode, ByRef, HirId, Mutability};
-use rustc_middle::middle::codegen_fn_attrs::TargetFeature;
+use rustc_hir::{self as hir, BindingMode, ByRef, HirId, Mutability, find_attr};
+use rustc_middle::middle::codegen_fn_attrs::{TargetFeature, TargetFeatureKind};
 use rustc_middle::mir::BorrowKind;
 use rustc_middle::span_bug;
 use rustc_middle::thir::visit::Visitor;
@@ -521,7 +522,7 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
                             .iter()
                             .copied()
                             .filter(|feature| {
-                                !feature.implied
+                                feature.kind == TargetFeatureKind::Enabled
                                     && !self
                                         .body_target_features
                                         .iter()
@@ -1157,7 +1158,7 @@ pub(crate) fn check_unsafety(tcx: TyCtxt<'_>, def: LocalDefId) {
     // Closures and inline consts are handled by their owner, if it has a body
     assert!(!tcx.is_typeck_child(def.to_def_id()));
     // Also, don't safety check custom MIR
-    if tcx.has_attr(def, sym::custom_mir) {
+    if find_attr!(tcx.get_all_attrs(def), AttributeKind::CustomMir(..) => ()).is_some() {
         return;
     }
 
diff --git a/compiler/rustc_mir_build/src/thir/cx/mod.rs b/compiler/rustc_mir_build/src/thir/cx/mod.rs
index 24d4136c642..9657c4dc839 100644
--- a/compiler/rustc_mir_build/src/thir/cx/mod.rs
+++ b/compiler/rustc_mir_build/src/thir/cx/mod.rs
@@ -4,11 +4,11 @@
 
 use rustc_data_structures::steal::Steal;
 use rustc_errors::ErrorGuaranteed;
-use rustc_hir as hir;
-use rustc_hir::HirId;
+use rustc_hir::attrs::AttributeKind;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::lang_items::LangItem;
+use rustc_hir::{self as hir, HirId, find_attr};
 use rustc_middle::bug;
 use rustc_middle::middle::region;
 use rustc_middle::thir::*;
@@ -111,10 +111,8 @@ impl<'tcx> ThirBuildCx<'tcx> {
             typeck_results,
             rvalue_scopes: &typeck_results.rvalue_scopes,
             body_owner: def.to_def_id(),
-            apply_adjustments: tcx
-                .hir_attrs(hir_id)
-                .iter()
-                .all(|attr| !attr.has_name(rustc_span::sym::custom_mir)),
+            apply_adjustments:
+                !find_attr!(tcx.hir_attrs(hir_id), AttributeKind::CustomMir(..) => ()).is_some(),
         }
     }
 
diff --git a/compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs b/compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs
index a501cdf88c2..d46c4678bcf 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs
@@ -11,11 +11,11 @@ use rustc_index::Idx;
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_infer::traits::Obligation;
 use rustc_middle::mir::interpret::ErrorHandled;
+use rustc_middle::span_bug;
 use rustc_middle::thir::{FieldPat, Pat, PatKind};
 use rustc_middle::ty::{
     self, Ty, TyCtxt, TypeSuperVisitable, TypeVisitableExt, TypeVisitor, ValTree,
 };
-use rustc_middle::{mir, span_bug};
 use rustc_span::def_id::DefId;
 use rustc_span::{DUMMY_SP, Span};
 use rustc_trait_selection::traits::ObligationCause;
@@ -288,16 +288,12 @@ impl<'tcx> ConstToPat<'tcx> {
                 // when lowering to MIR in `Builder::perform_test`, treat the constant as a `&str`.
                 // This works because `str` and `&str` have the same valtree representation.
                 let ref_str_ty = Ty::new_imm_ref(tcx, tcx.lifetimes.re_erased, ty);
-                PatKind::Constant {
-                    value: mir::Const::Ty(ref_str_ty, ty::Const::new_value(tcx, cv, ref_str_ty)),
-                }
+                PatKind::Constant { value: ty::Value { ty: ref_str_ty, valtree: cv } }
             }
             ty::Ref(_, pointee_ty, ..) => match *pointee_ty.kind() {
                 // `&str` is represented as a valtree, let's keep using this
                 // optimization for now.
-                ty::Str => PatKind::Constant {
-                    value: mir::Const::Ty(ty, ty::Const::new_value(tcx, cv, ty)),
-                },
+                ty::Str => PatKind::Constant { value: ty::Value { ty, valtree: cv } },
                 // All other references are converted into deref patterns and then recursively
                 // convert the dereferenced constant to a pattern that is the sub-pattern of the
                 // deref pattern.
@@ -326,15 +322,13 @@ impl<'tcx> ConstToPat<'tcx> {
                     // Also see <https://github.com/rust-lang/rfcs/pull/3535>.
                     return self.mk_err(tcx.dcx().create_err(NaNPattern { span }), ty);
                 } else {
-                    PatKind::Constant {
-                        value: mir::Const::Ty(ty, ty::Const::new_value(tcx, cv, ty)),
-                    }
+                    PatKind::Constant { value: ty::Value { ty, valtree: cv } }
                 }
             }
             ty::Pat(..) | ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::RawPtr(..) => {
                 // The raw pointers we see here have been "vetted" by valtree construction to be
                 // just integers, so we simply allow them.
-                PatKind::Constant { value: mir::Const::Ty(ty, ty::Const::new_value(tcx, cv, ty)) }
+                PatKind::Constant { value: ty::Value { ty, valtree: cv } }
             }
             ty::FnPtr(..) => {
                 unreachable!(
diff --git a/compiler/rustc_mir_build/src/thir/pattern/mod.rs b/compiler/rustc_mir_build/src/thir/pattern/mod.rs
index a44afed5492..166e64a5fcb 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/mod.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/mod.rs
@@ -161,8 +161,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
                 format!("found bad range pattern endpoint `{expr:?}` outside of error recovery");
             return Err(self.tcx.dcx().span_delayed_bug(expr.span, msg));
         };
-
-        Ok(Some(PatRangeBoundary::Finite(value)))
+        Ok(Some(PatRangeBoundary::Finite(value.valtree)))
     }
 
     /// Overflowing literals are linted against in a late pass. This is mostly fine, except when we
@@ -235,7 +234,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
         let lo = lower_endpoint(lo_expr)?.unwrap_or(PatRangeBoundary::NegInfinity);
         let hi = lower_endpoint(hi_expr)?.unwrap_or(PatRangeBoundary::PosInfinity);
 
-        let cmp = lo.compare_with(hi, ty, self.tcx, self.typing_env);
+        let cmp = lo.compare_with(hi, ty, self.tcx);
         let mut kind = PatKind::Range(Arc::new(PatRange { lo, hi, end, ty }));
         match (end, cmp) {
             // `x..y` where `x < y`.
@@ -244,7 +243,8 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
             (RangeEnd::Included, Some(Ordering::Less)) => {}
             // `x..=y` where `x == y` and `x` and `y` are finite.
             (RangeEnd::Included, Some(Ordering::Equal)) if lo.is_finite() && hi.is_finite() => {
-                kind = PatKind::Constant { value: lo.as_finite().unwrap() };
+                let value = ty::Value { ty, valtree: lo.as_finite().unwrap() };
+                kind = PatKind::Constant { value };
             }
             // `..=x` where `x == ty::MIN`.
             (RangeEnd::Included, Some(Ordering::Equal)) if !lo.is_finite() => {}
diff --git a/compiler/rustc_mir_build/src/thir/print.rs b/compiler/rustc_mir_build/src/thir/print.rs
index 5efc4be2de2..b7e8d6fea40 100644
--- a/compiler/rustc_mir_build/src/thir/print.rs
+++ b/compiler/rustc_mir_build/src/thir/print.rs
@@ -763,7 +763,7 @@ impl<'a, 'tcx> ThirPrinter<'a, 'tcx> {
             }
             PatKind::Constant { value } => {
                 print_indented!(self, "Constant {", depth_lvl + 1);
-                print_indented!(self, format!("value: {:?}", value), depth_lvl + 2);
+                print_indented!(self, format!("value: {}", value), depth_lvl + 2);
                 print_indented!(self, "}", depth_lvl + 1);
             }
             PatKind::ExpandedConstant { def_id, subpattern } => {
diff --git a/compiler/rustc_mir_dataflow/Cargo.toml b/compiler/rustc_mir_dataflow/Cargo.toml
index 293bcbef21b..e422f69c7ca 100644
--- a/compiler/rustc_mir_dataflow/Cargo.toml
+++ b/compiler/rustc_mir_dataflow/Cargo.toml
@@ -13,11 +13,10 @@ rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
 rustc_fluent_macro = { path = "../rustc_fluent_macro" }
 rustc_graphviz = { path = "../rustc_graphviz" }
-rustc_hir = { path = "../rustc_hir" }
 rustc_index = { path = "../rustc_index" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_middle = { path = "../rustc_middle" }
 rustc_span = { path = "../rustc_span" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_mir_dataflow/src/framework/graphviz.rs b/compiler/rustc_mir_dataflow/src/framework/graphviz.rs
index f86a15a8f92..372a3f3a8b8 100644
--- a/compiler/rustc_mir_dataflow/src/framework/graphviz.rs
+++ b/compiler/rustc_mir_dataflow/src/framework/graphviz.rs
@@ -8,7 +8,6 @@ use std::sync::OnceLock;
 use std::{io, ops, str};
 
 use regex::Regex;
-use rustc_hir::def_id::DefId;
 use rustc_index::bit_set::DenseBitSet;
 use rustc_middle::mir::{
     self, BasicBlock, Body, Location, create_dump_file, dump_enabled, graphviz_safe_def_name,
@@ -16,6 +15,7 @@ use rustc_middle::mir::{
 };
 use rustc_middle::ty::TyCtxt;
 use rustc_middle::ty::print::with_no_trimmed_paths;
+use rustc_span::def_id::DefId;
 use rustc_span::{Symbol, sym};
 use tracing::debug;
 use {rustc_ast as ast, rustc_graphviz as dot};
diff --git a/compiler/rustc_mir_dataflow/src/move_paths/abs_domain.rs b/compiler/rustc_mir_dataflow/src/move_paths/abs_domain.rs
deleted file mode 100644
index d056ad3d4b4..00000000000
--- a/compiler/rustc_mir_dataflow/src/move_paths/abs_domain.rs
+++ /dev/null
@@ -1,38 +0,0 @@
-//! The move-analysis portion of borrowck needs to work in an abstract
-//! domain of lifted `Place`s. Most of the `Place` variants fall into a
-//! one-to-one mapping between the concrete and abstract (e.g., a
-//! field-deref on a local variable, `x.field`, has the same meaning
-//! in both domains). Indexed projections are the exception: `a[x]`
-//! needs to be treated as mapping to the same move path as `a[y]` as
-//! well as `a[13]`, etc. So we map these `x`/`y` values to `()`.
-//!
-//! (In theory, the analysis could be extended to work with sets of
-//! paths, so that `a[0]` and `a[13]` could be kept distinct, while
-//! `a[x]` would still overlap them both. But that is not this
-//! representation does today.)
-
-use rustc_middle::mir::{PlaceElem, ProjectionElem, ProjectionKind};
-
-pub(crate) trait Lift {
-    fn lift(&self) -> ProjectionKind;
-}
-
-impl<'tcx> Lift for PlaceElem<'tcx> {
-    fn lift(&self) -> ProjectionKind {
-        match *self {
-            ProjectionElem::Deref => ProjectionElem::Deref,
-            ProjectionElem::Field(f, _ty) => ProjectionElem::Field(f, ()),
-            ProjectionElem::OpaqueCast(_ty) => ProjectionElem::OpaqueCast(()),
-            ProjectionElem::Index(_i) => ProjectionElem::Index(()),
-            ProjectionElem::Subslice { from, to, from_end } => {
-                ProjectionElem::Subslice { from, to, from_end }
-            }
-            ProjectionElem::ConstantIndex { offset, min_length, from_end } => {
-                ProjectionElem::ConstantIndex { offset, min_length, from_end }
-            }
-            ProjectionElem::Downcast(a, u) => ProjectionElem::Downcast(a, u),
-            ProjectionElem::Subtype(_ty) => ProjectionElem::Subtype(()),
-            ProjectionElem::UnwrapUnsafeBinder(_ty) => ProjectionElem::UnwrapUnsafeBinder(()),
-        }
-    }
-}
diff --git a/compiler/rustc_mir_dataflow/src/move_paths/builder.rs b/compiler/rustc_mir_dataflow/src/move_paths/builder.rs
index 8bbc89fdcec..48718cad597 100644
--- a/compiler/rustc_mir_dataflow/src/move_paths/builder.rs
+++ b/compiler/rustc_mir_dataflow/src/move_paths/builder.rs
@@ -7,7 +7,6 @@ use rustc_middle::{bug, span_bug};
 use smallvec::{SmallVec, smallvec};
 use tracing::debug;
 
-use super::abs_domain::Lift;
 use super::{
     Init, InitIndex, InitKind, InitLocation, LocationMap, LookupResult, MoveData, MoveOut,
     MoveOutIndex, MovePath, MovePathIndex, MovePathLookup,
@@ -241,7 +240,7 @@ impl<'a, 'tcx, F: Fn(Ty<'tcx>) -> bool> MoveDataBuilder<'a, 'tcx, F> {
             if union_path.is_none() {
                 // inlined from add_move_path because of a borrowck conflict with the iterator
                 base =
-                    *data.rev_lookup.projections.entry((base, elem.lift())).or_insert_with(|| {
+                    *data.rev_lookup.projections.entry((base, elem.kind())).or_insert_with(|| {
                         new_move_path(
                             &mut data.move_paths,
                             &mut data.path_map,
@@ -272,7 +271,7 @@ impl<'a, 'tcx, F: Fn(Ty<'tcx>) -> bool> MoveDataBuilder<'a, 'tcx, F> {
             tcx,
             ..
         } = self;
-        *rev_lookup.projections.entry((base, elem.lift())).or_insert_with(move || {
+        *rev_lookup.projections.entry((base, elem.kind())).or_insert_with(move || {
             new_move_path(move_paths, path_map, init_path_map, Some(base), mk_place(*tcx))
         })
     }
diff --git a/compiler/rustc_mir_dataflow/src/move_paths/mod.rs b/compiler/rustc_mir_dataflow/src/move_paths/mod.rs
index 18985ba0da2..466416d63f5 100644
--- a/compiler/rustc_mir_dataflow/src/move_paths/mod.rs
+++ b/compiler/rustc_mir_dataflow/src/move_paths/mod.rs
@@ -1,3 +1,15 @@
+//! The move-analysis portion of borrowck needs to work in an abstract domain of lifted `Place`s.
+//! Most of the `Place` variants fall into a one-to-one mapping between the concrete and abstract
+//! (e.g., a field projection on a local variable, `x.field`, has the same meaning in both
+//! domains). In other words, all field projections for the same field on the same local do not
+//! have meaningfully different types if ever. Indexed projections are the exception: `a[x]` needs
+//! to be treated as mapping to the same move path as `a[y]` as well as `a[13]`, etc. So we map
+//! these `x`/`y` values to `()`.
+//!
+//! (In theory, the analysis could be extended to work with sets of paths, so that `a[0]` and
+//! `a[13]` could be kept distinct, while `a[x]` would still overlap them both. But that is not
+//! what this representation does today.)
+
 use std::fmt;
 use std::ops::{Index, IndexMut};
 
@@ -8,11 +20,8 @@ use rustc_middle::ty::{Ty, TyCtxt};
 use rustc_span::Span;
 use smallvec::SmallVec;
 
-use self::abs_domain::Lift;
 use crate::un_derefer::UnDerefer;
 
-mod abs_domain;
-
 rustc_index::newtype_index! {
     #[orderable]
     #[debug_format = "mp{}"]
@@ -324,7 +333,7 @@ impl<'tcx> MovePathLookup<'tcx> {
         };
 
         for (_, elem) in self.un_derefer.iter_projections(place) {
-            if let Some(&subpath) = self.projections.get(&(result, elem.lift())) {
+            if let Some(&subpath) = self.projections.get(&(result, elem.kind())) {
                 result = subpath;
             } else {
                 return LookupResult::Parent(Some(result));
diff --git a/compiler/rustc_mir_dataflow/src/rustc_peek.rs b/compiler/rustc_mir_dataflow/src/rustc_peek.rs
index 1682f332857..a899ec1fa88 100644
--- a/compiler/rustc_mir_dataflow/src/rustc_peek.rs
+++ b/compiler/rustc_mir_dataflow/src/rustc_peek.rs
@@ -1,7 +1,7 @@
 use rustc_ast::MetaItem;
-use rustc_hir::def_id::DefId;
 use rustc_middle::mir::{self, Body, Local, Location};
 use rustc_middle::ty::{self, Ty, TyCtxt};
+use rustc_span::def_id::DefId;
 use rustc_span::{Span, Symbol, sym};
 use tracing::{debug, info};
 
diff --git a/compiler/rustc_mir_transform/Cargo.toml b/compiler/rustc_mir_transform/Cargo.toml
index 08c43a4648c..16acec15e92 100644
--- a/compiler/rustc_mir_transform/Cargo.toml
+++ b/compiler/rustc_mir_transform/Cargo.toml
@@ -6,7 +6,7 @@ edition = "2024"
 [dependencies]
 # tidy-alphabetical-start
 either = "1"
-itertools = "0.12"
+itertools.workspace = true
 rustc_abi = { path = "../rustc_abi" }
 rustc_arena = { path = "../rustc_arena" }
 rustc_ast = { path = "../rustc_ast" }
@@ -26,5 +26,5 @@ rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 rustc_trait_selection = { path = "../rustc_trait_selection" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_mir_transform/src/check_call_recursion.rs b/compiler/rustc_mir_transform/src/check_call_recursion.rs
index 6d61ac2dd80..a9acb1da5a3 100644
--- a/compiler/rustc_mir_transform/src/check_call_recursion.rs
+++ b/compiler/rustc_mir_transform/src/check_call_recursion.rs
@@ -43,8 +43,8 @@ impl<'tcx> MirLint<'tcx> for CheckDropRecursion {
 
         // First check if `body` is an `fn drop()` of `Drop`
         if let DefKind::AssocFn = tcx.def_kind(def_id)
-        && let Some(trait_ref) =
-            tcx.impl_of_assoc(def_id.to_def_id()).and_then(|def_id| tcx.impl_trait_ref(def_id))
+        && let Some(impl_id) = tcx.trait_impl_of_assoc(def_id.to_def_id())
+        && let trait_ref = tcx.impl_trait_ref(impl_id).unwrap()
         && tcx.is_lang_item(trait_ref.instantiate_identity().def_id, LangItem::Drop)
         // avoid erroneous `Drop` impls from causing ICEs below
         && let sig = tcx.fn_sig(def_id).instantiate_identity()
diff --git a/compiler/rustc_mir_transform/src/check_enums.rs b/compiler/rustc_mir_transform/src/check_enums.rs
index 33a87cb9873..12447dc7cbb 100644
--- a/compiler/rustc_mir_transform/src/check_enums.rs
+++ b/compiler/rustc_mir_transform/src/check_enums.rs
@@ -48,6 +48,21 @@ impl<'tcx> crate::MirPass<'tcx> for CheckEnums {
                     let new_block = split_block(basic_blocks, location);
 
                     match check {
+                        EnumCheckType::Direct { op_size, .. }
+                        | EnumCheckType::WithNiche { op_size, .. }
+                            if op_size.bytes() == 0 =>
+                        {
+                            // It is never valid to use a ZST as a discriminant for an inhabited enum, but that will
+                            // have been caught by the type checker. Do nothing but ensure that a bug has been signaled.
+                            tcx.dcx().span_delayed_bug(
+                                source_info.span,
+                                "cannot build enum discriminant from zero-sized type",
+                            );
+                            basic_blocks[block].terminator = Some(Terminator {
+                                source_info,
+                                kind: TerminatorKind::Goto { target: new_block },
+                            });
+                        }
                         EnumCheckType::Direct { source_op, discr, op_size, valid_discrs } => {
                             insert_direct_enum_check(
                                 tcx,
diff --git a/compiler/rustc_mir_transform/src/check_packed_ref.rs b/compiler/rustc_mir_transform/src/check_packed_ref.rs
index dcb812c7899..100104e9de0 100644
--- a/compiler/rustc_mir_transform/src/check_packed_ref.rs
+++ b/compiler/rustc_mir_transform/src/check_packed_ref.rs
@@ -40,7 +40,7 @@ impl<'tcx> Visitor<'tcx> for PackedRefChecker<'_, 'tcx> {
         if context.is_borrow() && util::is_disaligned(self.tcx, self.body, self.typing_env, *place)
         {
             let def_id = self.body.source.instance.def_id();
-            if let Some(impl_def_id) = self.tcx.impl_of_assoc(def_id)
+            if let Some(impl_def_id) = self.tcx.trait_impl_of_assoc(def_id)
                 && self.tcx.is_builtin_derived(impl_def_id)
             {
                 // If we ever reach here it means that the generated derive
diff --git a/compiler/rustc_mir_transform/src/coverage/counters.rs b/compiler/rustc_mir_transform/src/coverage/counters.rs
index 5568d42ab8f..879a20e771d 100644
--- a/compiler/rustc_mir_transform/src/coverage/counters.rs
+++ b/compiler/rustc_mir_transform/src/coverage/counters.rs
@@ -16,7 +16,6 @@ use crate::coverage::graph::{BasicCoverageBlock, CoverageGraph};
 
 mod balanced_flow;
 pub(crate) mod node_flow;
-mod union_find;
 
 /// Struct containing the results of [`prepare_bcb_counters_data`].
 pub(crate) struct BcbCountersData {
diff --git a/compiler/rustc_mir_transform/src/coverage/counters/node_flow.rs b/compiler/rustc_mir_transform/src/coverage/counters/node_flow.rs
index 91ed54b8b59..e063f75887b 100644
--- a/compiler/rustc_mir_transform/src/coverage/counters/node_flow.rs
+++ b/compiler/rustc_mir_transform/src/coverage/counters/node_flow.rs
@@ -7,13 +7,12 @@
 //! (Knuth & Stevenson, 1973).
 
 use rustc_data_structures::graph;
+use rustc_data_structures::union_find::UnionFind;
 use rustc_index::bit_set::DenseBitSet;
 use rustc_index::{Idx, IndexSlice, IndexVec};
 pub(crate) use rustc_middle::mir::coverage::NodeFlowData;
 use rustc_middle::mir::coverage::Op;
 
-use crate::coverage::counters::union_find::UnionFind;
-
 #[cfg(test)]
 mod tests;
 
diff --git a/compiler/rustc_mir_transform/src/coverage/mappings.rs b/compiler/rustc_mir_transform/src/coverage/mappings.rs
index 46fe7c40826..8dbe564f517 100644
--- a/compiler/rustc_mir_transform/src/coverage/mappings.rs
+++ b/compiler/rustc_mir_transform/src/coverage/mappings.rs
@@ -1,51 +1,36 @@
 use rustc_index::IndexVec;
-use rustc_middle::mir::coverage::{BlockMarkerId, BranchSpan, CoverageInfoHi, CoverageKind};
+use rustc_middle::mir::coverage::{
+    BlockMarkerId, BranchSpan, CoverageInfoHi, CoverageKind, Mapping, MappingKind,
+};
 use rustc_middle::mir::{self, BasicBlock, StatementKind};
 use rustc_middle::ty::TyCtxt;
-use rustc_span::Span;
 
-use crate::coverage::graph::{BasicCoverageBlock, CoverageGraph};
+use crate::coverage::graph::CoverageGraph;
 use crate::coverage::hir_info::ExtractedHirInfo;
 use crate::coverage::spans::extract_refined_covspans;
 use crate::coverage::unexpand::unexpand_into_body_span;
 
-/// Associates an ordinary executable code span with its corresponding BCB.
-#[derive(Debug)]
-pub(super) struct CodeMapping {
-    pub(super) span: Span,
-    pub(super) bcb: BasicCoverageBlock,
-}
-
-#[derive(Debug)]
-pub(super) struct BranchPair {
-    pub(super) span: Span,
-    pub(super) true_bcb: BasicCoverageBlock,
-    pub(super) false_bcb: BasicCoverageBlock,
-}
-
 #[derive(Default)]
-pub(super) struct ExtractedMappings {
-    pub(super) code_mappings: Vec<CodeMapping>,
-    pub(super) branch_pairs: Vec<BranchPair>,
+pub(crate) struct ExtractedMappings {
+    pub(crate) mappings: Vec<Mapping>,
 }
 
-/// Extracts coverage-relevant spans from MIR, and associates them with
-/// their corresponding BCBs.
-pub(super) fn extract_all_mapping_info_from_mir<'tcx>(
+/// Extracts coverage-relevant spans from MIR, and uses them to create
+/// coverage mapping data for inclusion in MIR.
+pub(crate) fn extract_mappings_from_mir<'tcx>(
     tcx: TyCtxt<'tcx>,
     mir_body: &mir::Body<'tcx>,
     hir_info: &ExtractedHirInfo,
     graph: &CoverageGraph,
 ) -> ExtractedMappings {
-    let mut code_mappings = vec![];
-    let mut branch_pairs = vec![];
+    let mut mappings = vec![];
 
     // Extract ordinary code mappings from MIR statement/terminator spans.
-    extract_refined_covspans(tcx, mir_body, hir_info, graph, &mut code_mappings);
+    extract_refined_covspans(tcx, mir_body, hir_info, graph, &mut mappings);
 
-    branch_pairs.extend(extract_branch_pairs(mir_body, hir_info, graph));
+    extract_branch_mappings(mir_body, hir_info, graph, &mut mappings);
 
-    ExtractedMappings { code_mappings, branch_pairs }
+    ExtractedMappings { mappings }
 }
 
 fn resolve_block_markers(
@@ -69,19 +54,18 @@ fn resolve_block_markers(
     block_markers
 }
 
-pub(super) fn extract_branch_pairs(
+pub(super) fn extract_branch_mappings(
     mir_body: &mir::Body<'_>,
     hir_info: &ExtractedHirInfo,
     graph: &CoverageGraph,
-) -> Vec<BranchPair> {
-    let Some(coverage_info_hi) = mir_body.coverage_info_hi.as_deref() else { return vec![] };
+    mappings: &mut Vec<Mapping>,
+) {
+    let Some(coverage_info_hi) = mir_body.coverage_info_hi.as_deref() else { return };
 
     let block_markers = resolve_block_markers(coverage_info_hi, mir_body);
 
-    coverage_info_hi
-        .branch_spans
-        .iter()
-        .filter_map(|&BranchSpan { span: raw_span, true_marker, false_marker }| {
+    mappings.extend(coverage_info_hi.branch_spans.iter().filter_map(
+        |&BranchSpan { span: raw_span, true_marker, false_marker }| try {
             // For now, ignore any branch span that was introduced by
             // expansion. This makes things like assert macros less noisy.
             if !raw_span.ctxt().outer_expn_data().is_root() {
@@ -94,7 +78,7 @@ pub(super) fn extract_branch_pairs(
             let true_bcb = bcb_from_marker(true_marker)?;
             let false_bcb = bcb_from_marker(false_marker)?;
 
-            Some(BranchPair { span, true_bcb, false_bcb })
-        })
-        .collect::<Vec<_>>()
+            Mapping { span, kind: MappingKind::Branch { true_bcb, false_bcb } }
+        },
+    ));
 }
diff --git a/compiler/rustc_mir_transform/src/coverage/mod.rs b/compiler/rustc_mir_transform/src/coverage/mod.rs
index 47a87a2e94d..c5fef299244 100644
--- a/compiler/rustc_mir_transform/src/coverage/mod.rs
+++ b/compiler/rustc_mir_transform/src/coverage/mod.rs
@@ -1,4 +1,4 @@
-use rustc_middle::mir::coverage::{CoverageKind, FunctionCoverageInfo, Mapping, MappingKind};
+use rustc_middle::mir::coverage::{CoverageKind, FunctionCoverageInfo};
 use rustc_middle::mir::{self, BasicBlock, Statement, StatementKind, TerminatorKind};
 use rustc_middle::ty::TyCtxt;
 use tracing::{debug, debug_span, trace};
@@ -71,10 +71,8 @@ fn instrument_function_for_coverage<'tcx>(tcx: TyCtxt<'tcx>, mir_body: &mut mir:
 
     ////////////////////////////////////////////////////
     // Extract coverage spans and other mapping info from MIR.
-    let extracted_mappings =
-        mappings::extract_all_mapping_info_from_mir(tcx, mir_body, &hir_info, &graph);
-
-    let mappings = create_mappings(&extracted_mappings);
+    let ExtractedMappings { mappings } =
+        mappings::extract_mappings_from_mir(tcx, mir_body, &hir_info, &graph);
     if mappings.is_empty() {
         // No spans could be converted into valid mappings, so skip this function.
         debug!("no spans could be converted into valid mappings; skipping");
@@ -100,34 +98,6 @@ fn instrument_function_for_coverage<'tcx>(tcx: TyCtxt<'tcx>, mir_body: &mut mir:
     }));
 }
 
-/// For each coverage span extracted from MIR, create a corresponding mapping.
-///
-/// FIXME(Zalathar): This used to be where BCBs in the extracted mappings were
-/// resolved to a `CovTerm`. But that is now handled elsewhere, so this
-/// function can potentially be simplified even further.
-fn create_mappings(extracted_mappings: &ExtractedMappings) -> Vec<Mapping> {
-    // Fully destructure the mappings struct to make sure we don't miss any kinds.
-    let ExtractedMappings { code_mappings, branch_pairs } = extracted_mappings;
-    let mut mappings = Vec::new();
-
-    mappings.extend(code_mappings.iter().map(
-        // Ordinary code mappings are the simplest kind.
-        |&mappings::CodeMapping { span, bcb }| {
-            let kind = MappingKind::Code { bcb };
-            Mapping { kind, span }
-        },
-    ));
-
-    mappings.extend(branch_pairs.iter().map(
-        |&mappings::BranchPair { span, true_bcb, false_bcb }| {
-            let kind = MappingKind::Branch { true_bcb, false_bcb };
-            Mapping { kind, span }
-        },
-    ));
-
-    mappings
-}
-
 /// Inject any necessary coverage statements into MIR, so that they influence codegen.
 fn inject_coverage_statements<'tcx>(mir_body: &mut mir::Body<'tcx>, graph: &CoverageGraph) {
     for (bcb, data) in graph.iter_enumerated() {
diff --git a/compiler/rustc_mir_transform/src/coverage/spans.rs b/compiler/rustc_mir_transform/src/coverage/spans.rs
index ae9459dee84..d1b04c8f587 100644
--- a/compiler/rustc_mir_transform/src/coverage/spans.rs
+++ b/compiler/rustc_mir_transform/src/coverage/spans.rs
@@ -1,6 +1,6 @@
 use rustc_data_structures::fx::FxHashSet;
 use rustc_middle::mir;
-use rustc_middle::mir::coverage::START_BCB;
+use rustc_middle::mir::coverage::{Mapping, MappingKind, START_BCB};
 use rustc_middle::ty::TyCtxt;
 use rustc_span::source_map::SourceMap;
 use rustc_span::{BytePos, DesugaringKind, ExpnKind, MacroKind, Span};
@@ -9,7 +9,7 @@ use tracing::instrument;
 use crate::coverage::graph::{BasicCoverageBlock, CoverageGraph};
 use crate::coverage::hir_info::ExtractedHirInfo;
 use crate::coverage::spans::from_mir::{Hole, RawSpanFromMir, SpanFromMir};
-use crate::coverage::{mappings, unexpand};
+use crate::coverage::unexpand;
 
 mod from_mir;
 
@@ -18,7 +18,7 @@ pub(super) fn extract_refined_covspans<'tcx>(
     mir_body: &mir::Body<'tcx>,
     hir_info: &ExtractedHirInfo,
     graph: &CoverageGraph,
-    code_mappings: &mut Vec<mappings::CodeMapping>,
+    mappings: &mut Vec<Mapping>,
 ) {
     if hir_info.is_async_fn {
         // An async function desugars into a function that returns a future,
@@ -26,7 +26,7 @@ pub(super) fn extract_refined_covspans<'tcx>(
         // outer function will be unhelpful, so just keep the signature span
         // and ignore all of the spans in the MIR body.
         if let Some(span) = hir_info.fn_sig_span {
-            code_mappings.push(mappings::CodeMapping { span, bcb: START_BCB });
+            mappings.push(Mapping { span, kind: MappingKind::Code { bcb: START_BCB } })
         }
         return;
     }
@@ -111,9 +111,9 @@ pub(super) fn extract_refined_covspans<'tcx>(
     // Merge covspans that can be merged.
     covspans.dedup_by(|b, a| a.merge_if_eligible(b));
 
-    code_mappings.extend(covspans.into_iter().map(|Covspan { span, bcb }| {
+    mappings.extend(covspans.into_iter().map(|Covspan { span, bcb }| {
         // Each span produced by the refiner represents an ordinary code region.
-        mappings::CodeMapping { span, bcb }
+        Mapping { span, kind: MappingKind::Code { bcb } }
     }));
 }
 
diff --git a/compiler/rustc_mir_transform/src/gvn.rs b/compiler/rustc_mir_transform/src/gvn.rs
index 952da2cdf72..5a13394543b 100644
--- a/compiler/rustc_mir_transform/src/gvn.rs
+++ b/compiler/rustc_mir_transform/src/gvn.rs
@@ -447,26 +447,9 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
 
             Projection(base, elem) => {
                 let base = self.evaluated[base].as_ref()?;
-                let elem = match elem {
-                    ProjectionElem::Deref => ProjectionElem::Deref,
-                    ProjectionElem::Downcast(name, read_variant) => {
-                        ProjectionElem::Downcast(name, read_variant)
-                    }
-                    ProjectionElem::Field(f, ()) => ProjectionElem::Field(f, ty.ty),
-                    ProjectionElem::ConstantIndex { offset, min_length, from_end } => {
-                        ProjectionElem::ConstantIndex { offset, min_length, from_end }
-                    }
-                    ProjectionElem::Subslice { from, to, from_end } => {
-                        ProjectionElem::Subslice { from, to, from_end }
-                    }
-                    ProjectionElem::OpaqueCast(()) => ProjectionElem::OpaqueCast(ty.ty),
-                    ProjectionElem::Subtype(()) => ProjectionElem::Subtype(ty.ty),
-                    ProjectionElem::UnwrapUnsafeBinder(()) => {
-                        ProjectionElem::UnwrapUnsafeBinder(ty.ty)
-                    }
-                    // This should have been replaced by a `ConstantIndex` earlier.
-                    ProjectionElem::Index(_) => return None,
-                };
+                // `Index` by constants should have been replaced by `ConstantIndex` by
+                // `simplify_place_projection`.
+                let elem = elem.try_map(|_| None, |()| ty.ty)?;
                 self.ecx.project(base, elem).discard_err()?
             }
             Address { place, kind: _, provenance: _ } => {
@@ -476,13 +459,11 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
                 let local = self.locals[place.local]?;
                 let pointer = self.evaluated[local].as_ref()?;
                 let mut mplace = self.ecx.deref_pointer(pointer).discard_err()?;
-                for proj in place.projection.iter().skip(1) {
-                    // We have no call stack to associate a local with a value, so we cannot
-                    // interpret indexing.
-                    if matches!(proj, ProjectionElem::Index(_)) {
-                        return None;
-                    }
-                    mplace = self.ecx.project(&mplace, proj).discard_err()?;
+                for elem in place.projection.iter().skip(1) {
+                    // `Index` by constants should have been replaced by `ConstantIndex` by
+                    // `simplify_place_projection`.
+                    let elem = elem.try_map(|_| None, |ty| ty)?;
+                    mplace = self.ecx.project(&mplace, elem).discard_err()?;
                 }
                 let pointer = mplace.to_ref(&self.ecx);
                 ImmTy::from_immediate(pointer, ty).into()
@@ -902,27 +883,14 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
         proj: ProjectionElem<VnIndex, ()>,
         loc: Location,
     ) -> Option<PlaceElem<'tcx>> {
-        Some(match proj {
-            ProjectionElem::Deref => ProjectionElem::Deref,
-            ProjectionElem::Field(idx, ()) => ProjectionElem::Field(idx, ty),
-            ProjectionElem::Index(idx) => {
-                let Some(local) = self.try_as_local(idx, loc) else {
-                    return None;
-                };
+        proj.try_map(
+            |value| {
+                let local = self.try_as_local(value, loc)?;
                 self.reused_locals.insert(local);
-                ProjectionElem::Index(local)
-            }
-            ProjectionElem::ConstantIndex { offset, min_length, from_end } => {
-                ProjectionElem::ConstantIndex { offset, min_length, from_end }
-            }
-            ProjectionElem::Subslice { from, to, from_end } => {
-                ProjectionElem::Subslice { from, to, from_end }
-            }
-            ProjectionElem::Downcast(symbol, idx) => ProjectionElem::Downcast(symbol, idx),
-            ProjectionElem::OpaqueCast(()) => ProjectionElem::OpaqueCast(ty),
-            ProjectionElem::Subtype(()) => ProjectionElem::Subtype(ty),
-            ProjectionElem::UnwrapUnsafeBinder(()) => ProjectionElem::UnwrapUnsafeBinder(ty),
-        })
+                Some(local)
+            },
+            |()| ty,
+        )
     }
 
     fn simplify_aggregate_to_copy(
diff --git a/compiler/rustc_mir_transform/src/pass_manager.rs b/compiler/rustc_mir_transform/src/pass_manager.rs
index 7a8d3ba1ff1..5b3ddcc777b 100644
--- a/compiler/rustc_mir_transform/src/pass_manager.rs
+++ b/compiler/rustc_mir_transform/src/pass_manager.rs
@@ -41,19 +41,40 @@ fn to_profiler_name(type_name: &'static str) -> &'static str {
     })
 }
 
-// const wrapper for `if let Some((_, tail)) = name.rsplit_once(':') { tail } else { name }`
-const fn c_name(name: &'static str) -> &'static str {
+// A function that simplifies a pass's type_name. E.g. `Baz`, `Baz<'_>`,
+// `foo::bar::Baz`, and `foo::bar::Baz<'a, 'b>` all become `Baz`.
+//
+// It's `const` for perf reasons: it's called a lot, and doing the string
+// operations at runtime causes a non-trivial slowdown. If
+// `split_once`/`rsplit_once` become `const` its body could be simplified to
+// this:
+// ```ignore (fragment)
+// let name = if let Some((_, tail)) = name.rsplit_once(':') { tail } else { name };
+// let name = if let Some((head, _)) = name.split_once('<') { head } else { name };
+// name
+// ```
+const fn simplify_pass_type_name(name: &'static str) -> &'static str {
     // FIXME(const-hack) Simplify the implementation once more `str` methods get const-stable.
-    // and inline into call site
+
+    // Work backwards from the end. If a ':' is hit, strip it and everything before it.
     let bytes = name.as_bytes();
     let mut i = bytes.len();
     while i > 0 && bytes[i - 1] != b':' {
-        i = i - 1;
+        i -= 1;
     }
     let (_, bytes) = bytes.split_at(i);
+
+    // Work forwards from the start of what's left. If a '<' is hit, strip it and everything after
+    // it.
+    let mut i = 0;
+    while i < bytes.len() && bytes[i] != b'<' {
+        i += 1;
+    }
+    let (bytes, _) = bytes.split_at(i);
+
     match std::str::from_utf8(bytes) {
         Ok(name) => name,
-        Err(_) => name,
+        Err(_) => panic!(),
     }
 }
 
@@ -62,12 +83,7 @@ const fn c_name(name: &'static str) -> &'static str {
 /// loop that goes over each available MIR and applies `run_pass`.
 pub(super) trait MirPass<'tcx> {
     fn name(&self) -> &'static str {
-        // FIXME(const-hack) Simplify the implementation once more `str` methods get const-stable.
-        // See copypaste in `MirLint`
-        const {
-            let name = std::any::type_name::<Self>();
-            c_name(name)
-        }
+        const { simplify_pass_type_name(std::any::type_name::<Self>()) }
     }
 
     fn profiler_name(&self) -> &'static str {
@@ -101,12 +117,7 @@ pub(super) trait MirPass<'tcx> {
 /// disabled (via the `Lint` adapter).
 pub(super) trait MirLint<'tcx> {
     fn name(&self) -> &'static str {
-        // FIXME(const-hack) Simplify the implementation once more `str` methods get const-stable.
-        // See copypaste in `MirPass`
-        const {
-            let name = std::any::type_name::<Self>();
-            c_name(name)
-        }
+        const { simplify_pass_type_name(std::any::type_name::<Self>()) }
     }
 
     fn is_enabled(&self, _sess: &Session) -> bool {
diff --git a/compiler/rustc_mir_transform/src/ref_prop.rs b/compiler/rustc_mir_transform/src/ref_prop.rs
index d1c2d6b508f..6f61215cee2 100644
--- a/compiler/rustc_mir_transform/src/ref_prop.rs
+++ b/compiler/rustc_mir_transform/src/ref_prop.rs
@@ -79,6 +79,7 @@ impl<'tcx> crate::MirPass<'tcx> for ReferencePropagation {
     #[instrument(level = "trace", skip(self, tcx, body))]
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
         debug!(def_id = ?body.source.def_id());
+        move_to_copy_pointers(tcx, body);
         while propagate_ssa(tcx, body) {}
     }
 
@@ -87,11 +88,43 @@ impl<'tcx> crate::MirPass<'tcx> for ReferencePropagation {
     }
 }
 
+/// The SSA analysis done by [`SsaLocals`] treats [`Operand::Move`] as a read, even though in
+/// general [`Operand::Move`] represents pass-by-pointer where the callee can overwrite the
+/// pointee (Miri always considers the place deinitialized). CopyProp has a similar trick to
+/// turn [`Operand::Move`] into [`Operand::Copy`] when required for an optimization, but in this
+/// pass we just turn all moves of pointers into copies because pointers should be by-value anyway.
+fn move_to_copy_pointers<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
+    let mut visitor = MoveToCopyVisitor { tcx, local_decls: &body.local_decls };
+    for (bb, data) in body.basic_blocks.as_mut_preserves_cfg().iter_enumerated_mut() {
+        visitor.visit_basic_block_data(bb, data);
+    }
+
+    struct MoveToCopyVisitor<'a, 'tcx> {
+        tcx: TyCtxt<'tcx>,
+        local_decls: &'a IndexVec<Local, LocalDecl<'tcx>>,
+    }
+
+    impl<'a, 'tcx> MutVisitor<'tcx> for MoveToCopyVisitor<'a, 'tcx> {
+        fn tcx(&self) -> TyCtxt<'tcx> {
+            self.tcx
+        }
+
+        fn visit_operand(&mut self, operand: &mut Operand<'tcx>, loc: Location) {
+            if let Operand::Move(place) = *operand {
+                if place.ty(self.local_decls, self.tcx).ty.is_any_ptr() {
+                    *operand = Operand::Copy(place);
+                }
+            }
+            self.super_operand(operand, loc);
+        }
+    }
+}
+
 fn propagate_ssa<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) -> bool {
     let typing_env = body.typing_env(tcx);
     let ssa = SsaLocals::new(tcx, body, typing_env);
 
-    let mut replacer = compute_replacement(tcx, body, &ssa);
+    let mut replacer = compute_replacement(tcx, body, ssa);
     debug!(?replacer.targets);
     debug!(?replacer.allowed_replacements);
     debug!(?replacer.storage_to_remove);
@@ -119,7 +152,7 @@ enum Value<'tcx> {
 fn compute_replacement<'tcx>(
     tcx: TyCtxt<'tcx>,
     body: &Body<'tcx>,
-    ssa: &SsaLocals,
+    ssa: SsaLocals,
 ) -> Replacer<'tcx> {
     let always_live_locals = always_storage_live_locals(body);
 
@@ -138,7 +171,7 @@ fn compute_replacement<'tcx>(
     // reborrowed references.
     let mut storage_to_remove = DenseBitSet::new_empty(body.local_decls.len());
 
-    let fully_replaceable_locals = fully_replaceable_locals(ssa);
+    let fully_replaceable_locals = fully_replaceable_locals(&ssa);
 
     // Returns true iff we can use `place` as a pointee.
     //
diff --git a/compiler/rustc_mir_transform/src/shim.rs b/compiler/rustc_mir_transform/src/shim.rs
index c687036f544..c6760b3583f 100644
--- a/compiler/rustc_mir_transform/src/shim.rs
+++ b/compiler/rustc_mir_transform/src/shim.rs
@@ -75,7 +75,7 @@ fn make_shim<'tcx>(tcx: TyCtxt<'tcx>, instance: ty::InstanceKind<'tcx>) -> Body<
             build_call_shim(tcx, instance, Some(adjustment), CallKind::Direct(def_id))
         }
         ty::InstanceKind::FnPtrShim(def_id, ty) => {
-            let trait_ = tcx.trait_of_assoc(def_id).unwrap();
+            let trait_ = tcx.parent(def_id);
             // Supports `Fn` or `async Fn` traits.
             let adjustment = match tcx
                 .fn_trait_kind_from_def_id(trait_)
diff --git a/compiler/rustc_monomorphize/Cargo.toml b/compiler/rustc_monomorphize/Cargo.toml
index 0ed5b4fc0d0..b11084cf169 100644
--- a/compiler/rustc_monomorphize/Cargo.toml
+++ b/compiler/rustc_monomorphize/Cargo.toml
@@ -6,7 +6,6 @@ edition = "2024"
 [dependencies]
 # tidy-alphabetical-start
 rustc_abi = { path = "../rustc_abi" }
-rustc_ast = { path = "../rustc_ast" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
 rustc_fluent_macro = { path = "../rustc_fluent_macro" }
@@ -15,9 +14,8 @@ rustc_macros = { path = "../rustc_macros" }
 rustc_middle = { path = "../rustc_middle" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
-rustc_symbol_mangling = { path = "../rustc_symbol_mangling" }
 rustc_target = { path = "../rustc_target" }
 serde = "1"
 serde_json = "1"
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_monomorphize/src/collector.rs b/compiler/rustc_monomorphize/src/collector.rs
index 26ca8518434..6a836442c32 100644
--- a/compiler/rustc_monomorphize/src/collector.rs
+++ b/compiler/rustc_monomorphize/src/collector.rs
@@ -205,6 +205,8 @@
 //! this is not implemented however: a mono item will be produced
 //! regardless of whether it is actually needed or not.
 
+mod autodiff;
+
 use std::cell::OnceCell;
 
 use rustc_data_structures::fx::FxIndexMap;
@@ -235,6 +237,7 @@ use rustc_span::source_map::{Spanned, dummy_spanned, respan};
 use rustc_span::{DUMMY_SP, Span};
 use tracing::{debug, instrument, trace};
 
+use crate::collector::autodiff::collect_autodiff_fn;
 use crate::errors::{
     self, EncounteredErrorWhileInstantiating, EncounteredErrorWhileInstantiatingGlobalAsm,
     NoOptimizedMir, RecursionLimit,
@@ -786,7 +789,35 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> {
                 // *Before* monomorphizing, record that we already handled this mention.
                 self.used_mentioned_items.insert(MentionedItem::Fn(callee_ty));
                 let callee_ty = self.monomorphize(callee_ty);
-                visit_fn_use(self.tcx, callee_ty, true, source, &mut self.used_items)
+
+                // HACK(explicit_tail_calls): collect tail calls to `#[track_caller]` functions as indirect,
+                // because we later call them as such, to prevent issues with ABI incompatibility.
+                // Ideally we'd replace such tail calls with normal call + return, but this requires
+                // post-mono MIR optimizations, which we don't yet have.
+                let force_indirect_call =
+                    if matches!(terminator.kind, mir::TerminatorKind::TailCall { .. })
+                        && let &ty::FnDef(def_id, args) = callee_ty.kind()
+                        && let instance = ty::Instance::expect_resolve(
+                            self.tcx,
+                            ty::TypingEnv::fully_monomorphized(),
+                            def_id,
+                            args,
+                            source,
+                        )
+                        && instance.def.requires_caller_location(self.tcx)
+                    {
+                        true
+                    } else {
+                        false
+                    };
+
+                visit_fn_use(
+                    self.tcx,
+                    callee_ty,
+                    !force_indirect_call,
+                    source,
+                    &mut self.used_items,
+                )
             }
             mir::TerminatorKind::Drop { ref place, .. } => {
                 let ty = place.ty(self.body, self.tcx).ty;
@@ -911,6 +942,8 @@ fn visit_instance_use<'tcx>(
         return;
     }
     if let Some(intrinsic) = tcx.intrinsic(instance.def_id()) {
+        collect_autodiff_fn(tcx, instance, intrinsic, output);
+
         if let Some(_requirement) = ValidityRequirement::from_intrinsic(intrinsic.name) {
             // The intrinsics assert_inhabited, assert_zero_valid, and assert_mem_uninitialized_valid will
             // be lowered in codegen to nothing or a call to panic_nounwind. So if we encounter any
diff --git a/compiler/rustc_monomorphize/src/collector/autodiff.rs b/compiler/rustc_monomorphize/src/collector/autodiff.rs
new file mode 100644
index 00000000000..13868cca944
--- /dev/null
+++ b/compiler/rustc_monomorphize/src/collector/autodiff.rs
@@ -0,0 +1,48 @@
+use rustc_middle::bug;
+use rustc_middle::ty::{self, GenericArg, IntrinsicDef, TyCtxt};
+
+use crate::collector::{MonoItems, create_fn_mono_item};
+
+// Here, we force both primal and diff function to be collected in
+// mono so this does not interfere in `autodiff` intrinsics
+// codegen process. If they are unused, LLVM will remove them when
+// compiling with O3.
+pub(crate) fn collect_autodiff_fn<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    instance: ty::Instance<'tcx>,
+    intrinsic: IntrinsicDef,
+    output: &mut MonoItems<'tcx>,
+) {
+    if intrinsic.name != rustc_span::sym::autodiff {
+        return;
+    };
+
+    collect_autodiff_fn_from_arg(instance.args[0], tcx, output);
+}
+
+fn collect_autodiff_fn_from_arg<'tcx>(
+    arg: GenericArg<'tcx>,
+    tcx: TyCtxt<'tcx>,
+    output: &mut MonoItems<'tcx>,
+) {
+    let (instance, span) = match arg.kind() {
+        ty::GenericArgKind::Type(ty) => match ty.kind() {
+            ty::FnDef(def_id, substs) => {
+                let span = tcx.def_span(def_id);
+                let instance = ty::Instance::expect_resolve(
+                    tcx,
+                    ty::TypingEnv::non_body_analysis(tcx, def_id),
+                    *def_id,
+                    substs,
+                    span,
+                );
+
+                (instance, span)
+            }
+            _ => bug!("expected autodiff function"),
+        },
+        _ => bug!("expected type when matching autodiff arg"),
+    };
+
+    output.push(create_fn_mono_item(tcx, instance, span));
+}
diff --git a/compiler/rustc_monomorphize/src/partitioning.rs b/compiler/rustc_monomorphize/src/partitioning.rs
index d76b27d9970..d784d3540c4 100644
--- a/compiler/rustc_monomorphize/src/partitioning.rs
+++ b/compiler/rustc_monomorphize/src/partitioning.rs
@@ -92,8 +92,6 @@
 //! source-level module, functions from the same module will be available for
 //! inlining, even when they are not marked `#[inline]`.
 
-mod autodiff;
-
 use std::cmp;
 use std::collections::hash_map::Entry;
 use std::fs::{self, File};
@@ -104,7 +102,7 @@ use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
 use rustc_data_structures::sync;
 use rustc_data_structures::unord::{UnordMap, UnordSet};
 use rustc_hir::LangItem;
-use rustc_hir::attrs::InlineAttr;
+use rustc_hir::attrs::{InlineAttr, Linkage};
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, DefIdSet, LOCAL_CRATE};
 use rustc_hir::definitions::DefPathDataName;
@@ -112,7 +110,7 @@ use rustc_middle::bug;
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc_middle::middle::exported_symbols::{SymbolExportInfo, SymbolExportLevel};
 use rustc_middle::mir::mono::{
-    CodegenUnit, CodegenUnitNameBuilder, InstantiationMode, Linkage, MonoItem, MonoItemData,
+    CodegenUnit, CodegenUnitNameBuilder, InstantiationMode, MonoItem, MonoItemData,
     MonoItemPartitions, Visibility,
 };
 use rustc_middle::ty::print::{characteristic_def_id_of_type, with_no_trimmed_paths};
@@ -251,17 +249,7 @@ where
             always_export_generics,
         );
 
-        // We can't differentiate a function that got inlined.
-        let autodiff_active = cfg!(llvm_enzyme)
-            && matches!(mono_item, MonoItem::Fn(_))
-            && cx
-                .tcx
-                .codegen_fn_attrs(mono_item.def_id())
-                .autodiff_item
-                .as_ref()
-                .is_some_and(|ad| ad.is_active());
-
-        if !autodiff_active && visibility == Visibility::Hidden && can_be_internalized {
+        if visibility == Visibility::Hidden && can_be_internalized {
             internalization_candidates.insert(mono_item);
         }
         let size_estimate = mono_item.size_estimate(cx.tcx);
@@ -650,17 +638,18 @@ fn characteristic_def_id_of_mono_item<'tcx>(
             // its self-type. If the self-type does not provide a characteristic
             // DefId, we use the location of the impl after all.
 
-            if tcx.trait_of_assoc(def_id).is_some() {
+            let assoc_parent = tcx.assoc_parent(def_id);
+
+            if let Some((_, DefKind::Trait)) = assoc_parent {
                 let self_ty = instance.args.type_at(0);
                 // This is a default implementation of a trait method.
                 return characteristic_def_id_of_type(self_ty).or(Some(def_id));
             }
 
-            if let Some(impl_def_id) = tcx.impl_of_assoc(def_id) {
-                if tcx.sess.opts.incremental.is_some()
-                    && tcx
-                        .trait_id_of_impl(impl_def_id)
-                        .is_some_and(|def_id| tcx.is_lang_item(def_id, LangItem::Drop))
+            if let Some((impl_def_id, DefKind::Impl { of_trait })) = assoc_parent {
+                if of_trait
+                    && tcx.sess.opts.incremental.is_some()
+                    && tcx.is_lang_item(tcx.trait_id_of_impl(impl_def_id).unwrap(), LangItem::Drop)
                 {
                     // Put `Drop::drop` into the same cgu as `drop_in_place`
                     // since `drop_in_place` is the only thing that can
@@ -1156,27 +1145,15 @@ fn collect_and_partition_mono_items(tcx: TyCtxt<'_>, (): ()) -> MonoItemPartitio
         }
     }
 
-    #[cfg(not(llvm_enzyme))]
-    let autodiff_mono_items: Vec<_> = vec![];
-    #[cfg(llvm_enzyme)]
-    let mut autodiff_mono_items: Vec<_> = vec![];
     let mono_items: DefIdSet = items
         .iter()
         .filter_map(|mono_item| match *mono_item {
-            MonoItem::Fn(ref instance) => {
-                #[cfg(llvm_enzyme)]
-                autodiff_mono_items.push((mono_item, instance));
-                Some(instance.def_id())
-            }
+            MonoItem::Fn(ref instance) => Some(instance.def_id()),
             MonoItem::Static(def_id) => Some(def_id),
             _ => None,
         })
         .collect();
 
-    let autodiff_items =
-        autodiff::find_autodiff_source_functions(tcx, &usage_map, autodiff_mono_items);
-    let autodiff_items = tcx.arena.alloc_from_iter(autodiff_items);
-
     // Output monomorphization stats per def_id
     if let SwitchWithOptPath::Enabled(ref path) = tcx.sess.opts.unstable_opts.dump_mono_stats
         && let Err(err) =
@@ -1234,11 +1211,7 @@ fn collect_and_partition_mono_items(tcx: TyCtxt<'_>, (): ()) -> MonoItemPartitio
         }
     }
 
-    MonoItemPartitions {
-        all_mono_items: tcx.arena.alloc(mono_items),
-        codegen_units,
-        autodiff_items,
-    }
+    MonoItemPartitions { all_mono_items: tcx.arena.alloc(mono_items), codegen_units }
 }
 
 /// Outputs stats about instantiation counts and estimated size, per `MonoItem`'s
diff --git a/compiler/rustc_monomorphize/src/partitioning/autodiff.rs b/compiler/rustc_monomorphize/src/partitioning/autodiff.rs
deleted file mode 100644
index 22d593b80b8..00000000000
--- a/compiler/rustc_monomorphize/src/partitioning/autodiff.rs
+++ /dev/null
@@ -1,143 +0,0 @@
-use rustc_ast::expand::autodiff_attrs::{AutoDiffItem, DiffActivity};
-use rustc_hir::def_id::LOCAL_CRATE;
-use rustc_middle::bug;
-use rustc_middle::mir::mono::MonoItem;
-use rustc_middle::ty::{self, Instance, PseudoCanonicalInput, Ty, TyCtxt, TypingEnv};
-use rustc_symbol_mangling::symbol_name_for_instance_in_crate;
-use tracing::{debug, trace};
-
-use crate::partitioning::UsageMap;
-
-fn adjust_activity_to_abi<'tcx>(tcx: TyCtxt<'tcx>, fn_ty: Ty<'tcx>, da: &mut Vec<DiffActivity>) {
-    if !matches!(fn_ty.kind(), ty::FnDef(..)) {
-        bug!("expected fn def for autodiff, got {:?}", fn_ty);
-    }
-
-    // We don't actually pass the types back into the type system.
-    // All we do is decide how to handle the arguments.
-    let sig = fn_ty.fn_sig(tcx).skip_binder();
-
-    let mut new_activities = vec![];
-    let mut new_positions = vec![];
-    for (i, ty) in sig.inputs().iter().enumerate() {
-        if let Some(inner_ty) = ty.builtin_deref(true) {
-            if inner_ty.is_slice() {
-                // Now we need to figure out the size of each slice element in memory to allow
-                // safety checks and usability improvements in the backend.
-                let sty = match inner_ty.builtin_index() {
-                    Some(sty) => sty,
-                    None => {
-                        panic!("slice element type unknown");
-                    }
-                };
-                let pci = PseudoCanonicalInput {
-                    typing_env: TypingEnv::fully_monomorphized(),
-                    value: sty,
-                };
-
-                let layout = tcx.layout_of(pci);
-                let elem_size = match layout {
-                    Ok(layout) => layout.size,
-                    Err(_) => {
-                        bug!("autodiff failed to compute slice element size");
-                    }
-                };
-                let elem_size: u32 = elem_size.bytes() as u32;
-
-                // We know that the length will be passed as extra arg.
-                if !da.is_empty() {
-                    // We are looking at a slice. The length of that slice will become an
-                    // extra integer on llvm level. Integers are always const.
-                    // However, if the slice get's duplicated, we want to know to later check the
-                    // size. So we mark the new size argument as FakeActivitySize.
-                    // There is one FakeActivitySize per slice, so for convenience we store the
-                    // slice element size in bytes in it. We will use the size in the backend.
-                    let activity = match da[i] {
-                        DiffActivity::DualOnly
-                        | DiffActivity::Dual
-                        | DiffActivity::Dualv
-                        | DiffActivity::DuplicatedOnly
-                        | DiffActivity::Duplicated => {
-                            DiffActivity::FakeActivitySize(Some(elem_size))
-                        }
-                        DiffActivity::Const => DiffActivity::Const,
-                        _ => bug!("unexpected activity for ptr/ref"),
-                    };
-                    new_activities.push(activity);
-                    new_positions.push(i + 1);
-                }
-
-                continue;
-            }
-        }
-    }
-    // now add the extra activities coming from slices
-    // Reverse order to not invalidate the indices
-    for _ in 0..new_activities.len() {
-        let pos = new_positions.pop().unwrap();
-        let activity = new_activities.pop().unwrap();
-        da.insert(pos, activity);
-    }
-}
-
-pub(crate) fn find_autodiff_source_functions<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    usage_map: &UsageMap<'tcx>,
-    autodiff_mono_items: Vec<(&MonoItem<'tcx>, &Instance<'tcx>)>,
-) -> Vec<AutoDiffItem> {
-    let mut autodiff_items: Vec<AutoDiffItem> = vec![];
-    for (item, instance) in autodiff_mono_items {
-        let target_id = instance.def_id();
-        let cg_fn_attr = &tcx.codegen_fn_attrs(target_id).autodiff_item;
-        let Some(target_attrs) = cg_fn_attr else {
-            continue;
-        };
-        let mut input_activities: Vec<DiffActivity> = target_attrs.input_activity.clone();
-        if target_attrs.is_source() {
-            trace!("source found: {:?}", target_id);
-        }
-        if !target_attrs.apply_autodiff() {
-            continue;
-        }
-
-        let target_symbol = symbol_name_for_instance_in_crate(tcx, instance.clone(), LOCAL_CRATE);
-
-        let source =
-            usage_map.used_map.get(&item).unwrap().into_iter().find_map(|item| match *item {
-                MonoItem::Fn(ref instance_s) => {
-                    let source_id = instance_s.def_id();
-                    if let Some(ad) = &tcx.codegen_fn_attrs(source_id).autodiff_item
-                        && ad.is_active()
-                    {
-                        return Some(instance_s);
-                    }
-                    None
-                }
-                _ => None,
-            });
-        let inst = match source {
-            Some(source) => source,
-            None => continue,
-        };
-
-        debug!("source_id: {:?}", inst.def_id());
-        let fn_ty = inst.ty(tcx, ty::TypingEnv::fully_monomorphized());
-        assert!(fn_ty.is_fn());
-        adjust_activity_to_abi(tcx, fn_ty, &mut input_activities);
-        let symb = symbol_name_for_instance_in_crate(tcx, inst.clone(), LOCAL_CRATE);
-
-        let mut new_target_attrs = target_attrs.clone();
-        new_target_attrs.input_activity = input_activities;
-        let itm = new_target_attrs.into_item(symb, target_symbol);
-        autodiff_items.push(itm);
-    }
-
-    if !autodiff_items.is_empty() {
-        trace!("AUTODIFF ITEMS EXIST");
-        for item in &mut *autodiff_items {
-            trace!("{}", &item);
-        }
-    }
-
-    autodiff_items
-}
diff --git a/compiler/rustc_next_trait_solver/Cargo.toml b/compiler/rustc_next_trait_solver/Cargo.toml
index 05bcabad02f..8b66f30cf0e 100644
--- a/compiler/rustc_next_trait_solver/Cargo.toml
+++ b/compiler/rustc_next_trait_solver/Cargo.toml
@@ -11,7 +11,7 @@ rustc_index = { path = "../rustc_index", default-features = false }
 rustc_macros = { path = "../rustc_macros", optional = true }
 rustc_type_ir = { path = "../rustc_type_ir", default-features = false }
 rustc_type_ir_macros = { path = "../rustc_type_ir_macros" }
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
 
 [features]
diff --git a/compiler/rustc_next_trait_solver/src/canonicalizer.rs b/compiler/rustc_next_trait_solver/src/canonicalizer.rs
index 1bc35e599c7..da05c49756f 100644
--- a/compiler/rustc_next_trait_solver/src/canonicalizer.rs
+++ b/compiler/rustc_next_trait_solver/src/canonicalizer.rs
@@ -25,12 +25,8 @@ enum CanonicalizeInputKind {
     /// trait candidates relies on it when deciding whether a where-bound
     /// is trivial.
     ParamEnv,
-    /// When canonicalizing predicates, we don't keep `'static`. If we're
-    /// currently outside of the trait solver and canonicalize the root goal
-    /// during HIR typeck, we replace each occurance of a region with a
-    /// unique region variable. See the comment on `InferCtxt::in_hir_typeck`
-    /// for more details.
-    Predicate { is_hir_typeck_root_goal: bool },
+    /// When canonicalizing predicates, we don't keep `'static`.
+    Predicate,
 }
 
 /// Whether we're canonicalizing a query input or the query response.
@@ -191,7 +187,6 @@ impl<'a, D: SolverDelegate<Interner = I>, I: Interner> Canonicalizer<'a, D, I> {
     pub fn canonicalize_input<P: TypeFoldable<I>>(
         delegate: &'a D,
         variables: &'a mut Vec<I::GenericArg>,
-        is_hir_typeck_root_goal: bool,
         input: QueryInput<I, P>,
     ) -> ty::Canonical<I, QueryInput<I, P>> {
         // First canonicalize the `param_env` while keeping `'static`
@@ -201,9 +196,7 @@ impl<'a, D: SolverDelegate<Interner = I>, I: Interner> Canonicalizer<'a, D, I> {
         // while *mostly* reusing the canonicalizer from above.
         let mut rest_canonicalizer = Canonicalizer {
             delegate,
-            canonicalize_mode: CanonicalizeMode::Input(CanonicalizeInputKind::Predicate {
-                is_hir_typeck_root_goal,
-            }),
+            canonicalize_mode: CanonicalizeMode::Input(CanonicalizeInputKind::Predicate),
 
             variables,
             variable_lookup_table,
@@ -481,31 +474,13 @@ impl<D: SolverDelegate<Interner = I>, I: Interner> TypeFolder<I> for Canonicaliz
             }
         };
 
-        let var = if let CanonicalizeMode::Input(CanonicalizeInputKind::Predicate {
-            is_hir_typeck_root_goal: true,
-        }) = self.canonicalize_mode
-        {
-            let var = ty::BoundVar::from(self.variables.len());
-            self.variables.push(r.into());
-            self.var_kinds.push(kind);
-            var
-        } else {
-            self.get_or_insert_bound_var(r, kind)
-        };
+        let var = self.get_or_insert_bound_var(r, kind);
 
         Region::new_anon_bound(self.cx(), self.binder_index, var)
     }
 
     fn fold_ty(&mut self, t: I::Ty) -> I::Ty {
-        if let CanonicalizeMode::Input(CanonicalizeInputKind::Predicate {
-            is_hir_typeck_root_goal: true,
-        }) = self.canonicalize_mode
-        {
-            // If we're canonicalizing a root goal during HIR typeck, we
-            // must not use the `cache` as we want to map each occurrence
-            // of a region to a unique existential variable.
-            self.inner_fold_ty(t)
-        } else if let Some(&ty) = self.cache.get(&(self.binder_index, t)) {
+        if let Some(&ty) = self.cache.get(&(self.binder_index, t)) {
             ty
         } else {
             let res = self.inner_fold_ty(t);
diff --git a/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs b/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs
index 5e08c3a03d8..a4a8317912a 100644
--- a/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs
@@ -8,6 +8,7 @@ use std::ops::ControlFlow;
 use derive_where::derive_where;
 use rustc_type_ir::inherent::*;
 use rustc_type_ir::lang_items::TraitSolverLangItem;
+use rustc_type_ir::search_graph::CandidateHeadUsages;
 use rustc_type_ir::solve::SizedTraitKind;
 use rustc_type_ir::{
     self as ty, Interner, TypeFlags, TypeFoldable, TypeSuperVisitable, TypeVisitable,
@@ -33,10 +34,11 @@ enum AliasBoundKind {
 ///
 /// It consists of both the `source`, which describes how that goal would be proven,
 /// and the `result` when using the given `source`.
-#[derive_where(Clone, Debug; I: Interner)]
+#[derive_where(Debug; I: Interner)]
 pub(super) struct Candidate<I: Interner> {
     pub(super) source: CandidateSource<I>,
     pub(super) result: CanonicalResponse<I>,
+    pub(super) head_usages: CandidateHeadUsages,
 }
 
 /// Methods used to assemble candidates for either trait or projection goals.
@@ -116,8 +118,11 @@ where
         ecx: &mut EvalCtxt<'_, D>,
         goal: Goal<I, Self>,
         assumption: I::Clause,
-    ) -> Result<Candidate<I>, NoSolution> {
-        Self::fast_reject_assumption(ecx, goal, assumption)?;
+    ) -> Result<Candidate<I>, CandidateHeadUsages> {
+        match Self::fast_reject_assumption(ecx, goal, assumption) {
+            Ok(()) => {}
+            Err(NoSolution) => return Err(CandidateHeadUsages::default()),
+        }
 
         // Dealing with `ParamEnv` candidates is a bit of a mess as we need to lazily
         // check whether the candidate is global while considering normalization.
@@ -126,18 +131,23 @@ where
         // in `probe` even if the candidate does not apply before we get there. We handle this
         // by using a `Cell` here. We only ever write into it inside of `match_assumption`.
         let source = Cell::new(CandidateSource::ParamEnv(ParamEnvSource::Global));
-        ecx.probe(|result: &QueryResult<I>| inspect::ProbeKind::TraitCandidate {
-            source: source.get(),
-            result: *result,
-        })
-        .enter(|ecx| {
-            Self::match_assumption(ecx, goal, assumption, |ecx| {
-                ecx.try_evaluate_added_goals()?;
-                source.set(ecx.characterize_param_env_assumption(goal.param_env, assumption)?);
-                ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
+        let (result, head_usages) = ecx
+            .probe(|result: &QueryResult<I>| inspect::ProbeKind::TraitCandidate {
+                source: source.get(),
+                result: *result,
             })
-        })
-        .map(|result| Candidate { source: source.get(), result })
+            .enter_single_candidate(|ecx| {
+                Self::match_assumption(ecx, goal, assumption, |ecx| {
+                    ecx.try_evaluate_added_goals()?;
+                    source.set(ecx.characterize_param_env_assumption(goal.param_env, assumption)?);
+                    ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
+                })
+            });
+
+        match result {
+            Ok(result) => Ok(Candidate { source: source.get(), result, head_usages }),
+            Err(NoSolution) => Err(head_usages),
+        }
     }
 
     /// Try equating an assumption predicate against a goal's predicate. If it
@@ -355,6 +365,19 @@ pub(super) enum AssembleCandidatesFrom {
     EnvAndBounds,
 }
 
+/// This is currently used to track the [CandidateHeadUsages] of all failed `ParamEnv`
+/// candidates. This is then used to ignore their head usages in case there's another
+/// always applicable `ParamEnv` candidate. Look at how `param_env_head_usages` is
+/// used in the code for more details.
+///
+/// We could easily extend this to also ignore head usages of other ignored candidates.
+/// However, we currently don't have any tests where this matters and the complexity of
+/// doing so does not feel worth it for now.
+#[derive(Debug)]
+pub(super) struct FailedCandidateInfo {
+    pub param_env_head_usages: CandidateHeadUsages,
+}
+
 impl<D, I> EvalCtxt<'_, D>
 where
     D: SolverDelegate<Interner = I>,
@@ -364,16 +387,20 @@ where
         &mut self,
         goal: Goal<I, G>,
         assemble_from: AssembleCandidatesFrom,
-    ) -> Vec<Candidate<I>> {
+    ) -> (Vec<Candidate<I>>, FailedCandidateInfo) {
+        let mut candidates = vec![];
+        let mut failed_candidate_info =
+            FailedCandidateInfo { param_env_head_usages: CandidateHeadUsages::default() };
         let Ok(normalized_self_ty) =
             self.structurally_normalize_ty(goal.param_env, goal.predicate.self_ty())
         else {
-            return vec![];
+            return (candidates, failed_candidate_info);
         };
 
         if normalized_self_ty.is_ty_var() {
             debug!("self type has been normalized to infer");
-            return self.forced_ambiguity(MaybeCause::Ambiguity).into_iter().collect();
+            candidates.extend(self.forced_ambiguity(MaybeCause::Ambiguity));
+            return (candidates, failed_candidate_info);
         }
 
         let goal: Goal<I, G> = goal
@@ -382,16 +409,15 @@ where
         // normalizing the self type as well, since type variables are not uniquified.
         let goal = self.resolve_vars_if_possible(goal);
 
-        let mut candidates = vec![];
-
         if let TypingMode::Coherence = self.typing_mode()
             && let Ok(candidate) = self.consider_coherence_unknowable_candidate(goal)
         {
-            return vec![candidate];
+            candidates.push(candidate);
+            return (candidates, failed_candidate_info);
         }
 
         self.assemble_alias_bound_candidates(goal, &mut candidates);
-        self.assemble_param_env_candidates(goal, &mut candidates);
+        self.assemble_param_env_candidates(goal, &mut candidates, &mut failed_candidate_info);
 
         match assemble_from {
             AssembleCandidatesFrom::All => {
@@ -423,7 +449,7 @@ where
             AssembleCandidatesFrom::EnvAndBounds => {}
         }
 
-        candidates
+        (candidates, failed_candidate_info)
     }
 
     pub(super) fn forced_ambiguity(
@@ -584,9 +610,15 @@ where
         &mut self,
         goal: Goal<I, G>,
         candidates: &mut Vec<Candidate<I>>,
+        failed_candidate_info: &mut FailedCandidateInfo,
     ) {
         for assumption in goal.param_env.caller_bounds().iter() {
-            candidates.extend(G::probe_and_consider_param_env_candidate(self, goal, assumption));
+            match G::probe_and_consider_param_env_candidate(self, goal, assumption) {
+                Ok(candidate) => candidates.push(candidate),
+                Err(head_usages) => {
+                    failed_candidate_info.param_env_head_usages.merge_usages(head_usages)
+                }
+            }
         }
     }
 
@@ -661,7 +693,11 @@ where
                 if let Ok(result) =
                     self.evaluate_added_goals_and_make_canonical_response(Certainty::AMBIGUOUS)
                 {
-                    candidates.push(Candidate { source: CandidateSource::AliasBound, result });
+                    candidates.push(Candidate {
+                        source: CandidateSource::AliasBound,
+                        result,
+                        head_usages: CandidateHeadUsages::default(),
+                    });
                 }
                 return;
             }
@@ -959,7 +995,7 @@ where
                 // Even when a trait bound has been proven using a where-bound, we
                 // still need to consider alias-bounds for normalization, see
                 // `tests/ui/next-solver/alias-bound-shadowed-by-env.rs`.
-                let mut candidates: Vec<_> = self
+                let (mut candidates, _) = self
                     .assemble_and_evaluate_candidates(goal, AssembleCandidatesFrom::EnvAndBounds);
 
                 // We still need to prefer where-bounds over alias-bounds however.
@@ -972,23 +1008,20 @@ where
                     return inject_normalize_to_rigid_candidate(self);
                 }
 
-                if let Some(response) = self.try_merge_candidates(&candidates) {
+                if let Some((response, _)) = self.try_merge_candidates(&candidates) {
                     Ok(response)
                 } else {
                     self.flounder(&candidates)
                 }
             }
             TraitGoalProvenVia::Misc => {
-                let mut candidates =
+                let (mut candidates, _) =
                     self.assemble_and_evaluate_candidates(goal, AssembleCandidatesFrom::All);
 
                 // Prefer "orphaned" param-env normalization predicates, which are used
                 // (for example, and ideally only) when proving item bounds for an impl.
-                let candidates_from_env: Vec<_> = candidates
-                    .extract_if(.., |c| matches!(c.source, CandidateSource::ParamEnv(_)))
-                    .collect();
-                if let Some(response) = self.try_merge_candidates(&candidates_from_env) {
-                    return Ok(response);
+                if candidates.iter().any(|c| matches!(c.source, CandidateSource::ParamEnv(_))) {
+                    candidates.retain(|c| matches!(c.source, CandidateSource::ParamEnv(_)));
                 }
 
                 // We drop specialized impls to allow normalization via a final impl here. In case
@@ -997,7 +1030,7 @@ where
                 // means we can just ignore inference constraints and don't have to special-case
                 // constraining the normalized-to `term`.
                 self.filter_specialized_impls(AllowInferenceConstraints::Yes, &mut candidates);
-                if let Some(response) = self.try_merge_candidates(&candidates) {
+                if let Some((response, _)) = self.try_merge_candidates(&candidates) {
                     Ok(response)
                 } else {
                     self.flounder(&candidates)
diff --git a/compiler/rustc_next_trait_solver/src/solve/assembly/structural_traits.rs b/compiler/rustc_next_trait_solver/src/solve/assembly/structural_traits.rs
index faa86734d08..d25e74e7335 100644
--- a/compiler/rustc_next_trait_solver/src/solve/assembly/structural_traits.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/assembly/structural_traits.rs
@@ -75,17 +75,10 @@ where
             Ok(ty::Binder::dummy(vec![args.as_coroutine_closure().tupled_upvars_ty()]))
         }
 
-        ty::Coroutine(def_id, args) => {
-            let coroutine_args = args.as_coroutine();
-            Ok(ty::Binder::dummy(vec![
-                coroutine_args.tupled_upvars_ty(),
-                Ty::new_coroutine_witness(
-                    ecx.cx(),
-                    def_id,
-                    ecx.cx().mk_args(coroutine_args.parent_args().as_slice()),
-                ),
-            ]))
-        }
+        ty::Coroutine(def_id, args) => Ok(ty::Binder::dummy(vec![
+            args.as_coroutine().tupled_upvars_ty(),
+            Ty::new_coroutine_witness_for_coroutine(ecx.cx(), def_id, args),
+        ])),
 
         ty::CoroutineWitness(def_id, args) => Ok(ecx
             .cx()
@@ -251,14 +244,9 @@ where
             Movability::Static => Err(NoSolution),
             Movability::Movable => {
                 if ecx.cx().features().coroutine_clone() {
-                    let coroutine = args.as_coroutine();
                     Ok(ty::Binder::dummy(vec![
-                        coroutine.tupled_upvars_ty(),
-                        Ty::new_coroutine_witness(
-                            ecx.cx(),
-                            def_id,
-                            ecx.cx().mk_args(coroutine.parent_args().as_slice()),
-                        ),
+                        args.as_coroutine().tupled_upvars_ty(),
+                        Ty::new_coroutine_witness_for_coroutine(ecx.cx(), def_id, args),
                     ]))
                 } else {
                     Err(NoSolution)
diff --git a/compiler/rustc_next_trait_solver/src/solve/effect_goals.rs b/compiler/rustc_next_trait_solver/src/solve/effect_goals.rs
index 9a22bf58c03..b7ae9994c62 100644
--- a/compiler/rustc_next_trait_solver/src/solve/effect_goals.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/effect_goals.rs
@@ -6,7 +6,7 @@ use rustc_type_ir::inherent::*;
 use rustc_type_ir::lang_items::TraitSolverLangItem;
 use rustc_type_ir::solve::SizedTraitKind;
 use rustc_type_ir::solve::inspect::ProbeKind;
-use rustc_type_ir::{self as ty, Interner, elaborate};
+use rustc_type_ir::{self as ty, Interner, TypingMode, elaborate};
 use tracing::instrument;
 
 use super::assembly::{Candidate, structural_traits};
@@ -135,12 +135,16 @@ where
         }
 
         let impl_polarity = cx.impl_polarity(impl_def_id);
-        match impl_polarity {
+        let certainty = match impl_polarity {
             ty::ImplPolarity::Negative => return Err(NoSolution),
-            ty::ImplPolarity::Reservation => {
-                unimplemented!("reservation impl for const trait: {:?}", goal)
-            }
-            ty::ImplPolarity::Positive => {}
+            ty::ImplPolarity::Reservation => match ecx.typing_mode() {
+                TypingMode::Coherence => Certainty::AMBIGUOUS,
+                TypingMode::Analysis { .. }
+                | TypingMode::Borrowck { .. }
+                | TypingMode::PostBorrowckAnalysis { .. }
+                | TypingMode::PostAnalysis => return Err(NoSolution),
+            },
+            ty::ImplPolarity::Positive => Certainty::Yes,
         };
 
         if !cx.impl_is_const(impl_def_id) {
@@ -171,7 +175,7 @@ where
                 });
             ecx.add_goals(GoalSource::ImplWhereBound, const_conditions);
 
-            ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
+            ecx.evaluate_added_goals_and_make_canonical_response(certainty)
         })
     }
 
diff --git a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/canonical.rs b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/canonical.rs
index 74c5b49ea92..4644b145b18 100644
--- a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/canonical.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/canonical.rs
@@ -57,7 +57,6 @@ where
     /// This expects `goal` and `opaque_types` to be eager resolved.
     pub(super) fn canonicalize_goal(
         &self,
-        is_hir_typeck_root_goal: bool,
         goal: Goal<I, I::Predicate>,
         opaque_types: Vec<(ty::OpaqueTypeKey<I>, I::Ty)>,
     ) -> (Vec<I::GenericArg>, CanonicalInput<I, I::Predicate>) {
@@ -65,7 +64,6 @@ where
         let canonical = Canonicalizer::canonicalize_input(
             self.delegate,
             &mut orig_values,
-            is_hir_typeck_root_goal,
             QueryInput {
                 goal,
                 predefined_opaques_in_body: self
diff --git a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs
index 8671cc7c3d3..4f87902e46e 100644
--- a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs
@@ -4,11 +4,10 @@ use std::ops::ControlFlow;
 #[cfg(feature = "nightly")]
 use rustc_macros::HashStable_NoContext;
 use rustc_type_ir::data_structures::{HashMap, HashSet};
-use rustc_type_ir::fast_reject::DeepRejectCtxt;
 use rustc_type_ir::inherent::*;
 use rustc_type_ir::relate::Relate;
 use rustc_type_ir::relate::solver_relating::RelateExt;
-use rustc_type_ir::search_graph::PathKind;
+use rustc_type_ir::search_graph::{CandidateHeadUsages, PathKind};
 use rustc_type_ir::{
     self as ty, CanonicalVarValues, InferCtxtLike, Interner, TypeFoldable, TypeFolder,
     TypeSuperFoldable, TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor,
@@ -399,6 +398,10 @@ where
         result
     }
 
+    pub(super) fn ignore_candidate_head_usages(&mut self, usages: CandidateHeadUsages) {
+        self.search_graph.ignore_candidate_head_usages(usages);
+    }
+
     /// Recursively evaluates `goal`, returning whether any inference vars have
     /// been constrained and the certainty of the result.
     fn evaluate_goal(
@@ -455,10 +458,7 @@ where
         let opaque_types = self.delegate.clone_opaque_types_lookup_table();
         let (goal, opaque_types) = eager_resolve_vars(self.delegate, (goal, opaque_types));
 
-        let is_hir_typeck_root_goal = matches!(goal_evaluation_kind, GoalEvaluationKind::Root)
-            && self.delegate.in_hir_typeck();
-        let (orig_values, canonical_goal) =
-            self.canonicalize_goal(is_hir_typeck_root_goal, goal, opaque_types);
+        let (orig_values, canonical_goal) = self.canonicalize_goal(goal, opaque_types);
         let mut goal_evaluation =
             self.inspect.new_goal_evaluation(goal, &orig_values, goal_evaluation_kind);
         let canonical_result = self.search_graph.evaluate_goal(
@@ -1127,6 +1127,7 @@ where
         self.delegate.fetch_eligible_assoc_item(goal_trait_ref, trait_assoc_def_id, impl_def_id)
     }
 
+    #[instrument(level = "debug", skip(self), ret)]
     pub(super) fn register_hidden_type_in_storage(
         &mut self,
         opaque_type_key: ty::OpaqueTypeKey<I>,
@@ -1153,29 +1154,6 @@ where
         self.add_goals(GoalSource::AliasWellFormed, goals);
     }
 
-    // Do something for each opaque/hidden pair defined with `def_id` in the
-    // current inference context.
-    pub(super) fn probe_existing_opaque_ty(
-        &mut self,
-        key: ty::OpaqueTypeKey<I>,
-    ) -> Option<(ty::OpaqueTypeKey<I>, I::Ty)> {
-        // We shouldn't have any duplicate entries when using
-        // this function during `TypingMode::Analysis`.
-        let duplicate_entries = self.delegate.clone_duplicate_opaque_types();
-        assert!(duplicate_entries.is_empty(), "unexpected duplicates: {duplicate_entries:?}");
-        let mut matching = self.delegate.clone_opaque_types_lookup_table().into_iter().filter(
-            |(candidate_key, _)| {
-                candidate_key.def_id == key.def_id
-                    && DeepRejectCtxt::relate_rigid_rigid(self.cx())
-                        .args_may_unify(candidate_key.args, key.args)
-            },
-        );
-        let first = matching.next();
-        let second = matching.next();
-        assert_eq!(second, None);
-        first
-    }
-
     // Try to evaluate a const, or return `None` if the const is too generic.
     // This doesn't mean the const isn't evaluatable, though, and should be treated
     // as an ambiguity rather than no-solution.
diff --git a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/probe.rs b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/probe.rs
index ed0cedc4077..e5658ba32ff 100644
--- a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/probe.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/probe.rs
@@ -1,5 +1,6 @@
 use std::marker::PhantomData;
 
+use rustc_type_ir::search_graph::CandidateHeadUsages;
 use rustc_type_ir::{InferCtxtLike, Interner};
 use tracing::instrument;
 
@@ -25,6 +26,20 @@ where
     D: SolverDelegate<Interner = I>,
     I: Interner,
 {
+    pub(in crate::solve) fn enter_single_candidate(
+        self,
+        f: impl FnOnce(&mut EvalCtxt<'_, D>) -> T,
+    ) -> (T, CandidateHeadUsages) {
+        self.ecx.search_graph.enter_single_candidate();
+        let mut candidate_usages = CandidateHeadUsages::default();
+        let result = self.enter(|ecx| {
+            let result = f(ecx);
+            candidate_usages = ecx.search_graph.finish_single_candidate();
+            result
+        });
+        (result, candidate_usages)
+    }
+
     pub(in crate::solve) fn enter(self, f: impl FnOnce(&mut EvalCtxt<'_, D>) -> T) -> T {
         let ProbeCtxt { ecx: outer, probe_kind, _result } = self;
 
@@ -78,7 +93,8 @@ where
         self,
         f: impl FnOnce(&mut EvalCtxt<'_, D>) -> QueryResult<I>,
     ) -> Result<Candidate<I>, NoSolution> {
-        self.cx.enter(|ecx| f(ecx)).map(|result| Candidate { source: self.source, result })
+        let (result, head_usages) = self.cx.enter_single_candidate(f);
+        result.map(|result| Candidate { source: self.source, result, head_usages })
     }
 }
 
diff --git a/compiler/rustc_next_trait_solver/src/solve/mod.rs b/compiler/rustc_next_trait_solver/src/solve/mod.rs
index 2feebe270a6..c2745c878dc 100644
--- a/compiler/rustc_next_trait_solver/src/solve/mod.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/mod.rs
@@ -236,6 +236,12 @@ where
     }
 }
 
+#[derive(Debug)]
+enum MergeCandidateInfo {
+    AlwaysApplicable(usize),
+    EqualResponse,
+}
+
 impl<D, I> EvalCtxt<'_, D>
 where
     D: SolverDelegate<Interner = I>,
@@ -248,23 +254,25 @@ where
     fn try_merge_candidates(
         &mut self,
         candidates: &[Candidate<I>],
-    ) -> Option<CanonicalResponse<I>> {
+    ) -> Option<(CanonicalResponse<I>, MergeCandidateInfo)> {
         if candidates.is_empty() {
             return None;
         }
 
+        let always_applicable = candidates.iter().enumerate().find(|(_, candidate)| {
+            candidate.result.value.certainty == Certainty::Yes
+                && has_no_inference_or_external_constraints(candidate.result)
+        });
+        if let Some((i, c)) = always_applicable {
+            return Some((c.result, MergeCandidateInfo::AlwaysApplicable(i)));
+        }
+
         let one: CanonicalResponse<I> = candidates[0].result;
         if candidates[1..].iter().all(|candidate| candidate.result == one) {
-            return Some(one);
+            return Some((one, MergeCandidateInfo::EqualResponse));
         }
 
-        candidates
-            .iter()
-            .find(|candidate| {
-                candidate.result.value.certainty == Certainty::Yes
-                    && has_no_inference_or_external_constraints(candidate.result)
-            })
-            .map(|candidate| candidate.result)
+        None
     }
 
     fn bail_with_ambiguity(&mut self, candidates: &[Candidate<I>]) -> CanonicalResponse<I> {
diff --git a/compiler/rustc_next_trait_solver/src/solve/normalizes_to/opaque_types.rs b/compiler/rustc_next_trait_solver/src/solve/normalizes_to/opaque_types.rs
index df3ad1e468b..a5f857a1dd8 100644
--- a/compiler/rustc_next_trait_solver/src/solve/normalizes_to/opaque_types.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/normalizes_to/opaque_types.rs
@@ -1,13 +1,12 @@
 //! Computes a normalizes-to (projection) goal for opaque types. This goal
 //! behaves differently depending on the current `TypingMode`.
 
-use rustc_index::bit_set::GrowableBitSet;
 use rustc_type_ir::inherent::*;
 use rustc_type_ir::solve::GoalSource;
 use rustc_type_ir::{self as ty, Interner, TypingMode, fold_regions};
 
 use crate::delegate::SolverDelegate;
-use crate::solve::{Certainty, EvalCtxt, Goal, NoSolution, QueryResult, inspect};
+use crate::solve::{Certainty, EvalCtxt, Goal, QueryResult};
 
 impl<D, I> EvalCtxt<'_, D>
 where
@@ -39,100 +38,68 @@ where
                 self.add_goal(GoalSource::Misc, goal.with(cx, ty::PredicateKind::Ambiguous));
                 self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
             }
-            TypingMode::Analysis { defining_opaque_types_and_generators } => {
+            TypingMode::Analysis {
+                defining_opaque_types_and_generators: defining_opaque_types,
+            }
+            | TypingMode::Borrowck { defining_opaque_types } => {
                 let Some(def_id) = opaque_ty
                     .def_id
                     .as_local()
-                    .filter(|&def_id| defining_opaque_types_and_generators.contains(&def_id))
+                    .filter(|&def_id| defining_opaque_types.contains(&def_id))
                 else {
+                    // If we're not in the defining scope, treat the alias as rigid.
                     self.structurally_instantiate_normalizes_to_term(goal, goal.predicate.alias);
                     return self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes);
                 };
 
-                // FIXME: This may have issues when the args contain aliases...
-                match uses_unique_placeholders_ignoring_regions(self.cx(), opaque_ty.args) {
-                    Err(NotUniqueParam::NotParam(param)) if param.is_non_region_infer() => {
-                        return self.evaluate_added_goals_and_make_canonical_response(
-                            Certainty::AMBIGUOUS,
-                        );
-                    }
-                    Err(_) => {
-                        return Err(NoSolution);
-                    }
-                    Ok(()) => {}
-                }
-                // Prefer opaques registered already.
-                let opaque_type_key = ty::OpaqueTypeKey { def_id, args: opaque_ty.args };
-                // FIXME: This also unifies the previous hidden type with the expected.
+                // We structurally normalize the args so that we're able to detect defining uses
+                // later on.
                 //
-                // If that fails, we insert `expected` as a new hidden type instead of
-                // eagerly emitting an error.
-                let existing = self.probe_existing_opaque_ty(opaque_type_key);
-                if let Some((candidate_key, candidate_ty)) = existing {
-                    return self
-                        .probe(|result| inspect::ProbeKind::OpaqueTypeStorageLookup {
-                            result: *result,
-                        })
-                        .enter(|ecx| {
-                            for (a, b) in std::iter::zip(
-                                candidate_key.args.iter(),
-                                opaque_type_key.args.iter(),
-                            ) {
-                                ecx.eq(goal.param_env, a, b)?;
-                            }
-                            ecx.eq(goal.param_env, candidate_ty, expected)?;
-                            ecx.add_item_bounds_for_hidden_type(
-                                def_id.into(),
-                                candidate_key.args,
-                                goal.param_env,
-                                candidate_ty,
-                            );
-                            ecx.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
-                        });
-                }
+                // This reduces the amount of duplicate definitions in the `opaque_type_storage` and
+                // strengthens inference. This causes us to subtly depend on the normalization behavior
+                // when inferring the hidden type of opaques.
+                //
+                // E.g. it's observable that we don't normalize nested aliases with bound vars in
+                // `structurally_normalize` and because we use structural lookup, we also don't
+                // reuse an entry for `Tait<for<'a> fn(&'a ())>` for `Tait<for<'b> fn(&'b ())>`.
+                let normalized_args =
+                    cx.mk_args_from_iter(opaque_ty.args.iter().map(|arg| match arg.kind() {
+                        ty::GenericArgKind::Lifetime(lt) => Ok(lt.into()),
+                        ty::GenericArgKind::Type(ty) => {
+                            self.structurally_normalize_ty(goal.param_env, ty).map(Into::into)
+                        }
+                        ty::GenericArgKind::Const(ct) => {
+                            self.structurally_normalize_const(goal.param_env, ct).map(Into::into)
+                        }
+                    }))?;
 
-                // Otherwise, define a new opaque type
-                let prev = self.register_hidden_type_in_storage(opaque_type_key, expected);
-                assert_eq!(prev, None);
-                self.add_item_bounds_for_hidden_type(
-                    def_id.into(),
-                    opaque_ty.args,
-                    goal.param_env,
-                    expected,
-                );
-                self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
-            }
-            // Very similar to `TypingMode::Analysis` with some notably differences:
-            // - we accept opaque types even if they have non-universal arguments
-            // - we do a structural lookup instead of semantically unifying regions
-            // - the hidden type starts out as the type from HIR typeck with fresh region
-            //   variables instead of a fully unconstrained inference variable
-            TypingMode::Borrowck { defining_opaque_types } => {
-                let Some(def_id) = opaque_ty
-                    .def_id
-                    .as_local()
-                    .filter(|&def_id| defining_opaque_types.contains(&def_id))
-                else {
-                    self.structurally_instantiate_normalizes_to_term(goal, goal.predicate.alias);
-                    return self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes);
-                };
+                let opaque_type_key = ty::OpaqueTypeKey { def_id, args: normalized_args };
+                if let Some(prev) = self.register_hidden_type_in_storage(opaque_type_key, expected)
+                {
+                    self.eq(goal.param_env, expected, prev)?;
+                } else {
+                    // During HIR typeck, opaque types start out as unconstrained
+                    // inference variables. In borrowck we instead use the type
+                    // computed in HIR typeck as the initial value.
+                    match self.typing_mode() {
+                        TypingMode::Analysis { .. } => {}
+                        TypingMode::Borrowck { .. } => {
+                            let actual = cx
+                                .type_of_opaque_hir_typeck(def_id)
+                                .instantiate(cx, opaque_ty.args);
+                            let actual = fold_regions(cx, actual, |re, _dbi| match re.kind() {
+                                ty::ReErased => self.next_region_var(),
+                                _ => re,
+                            });
+                            self.eq(goal.param_env, expected, actual)?;
+                        }
+                        _ => unreachable!(),
+                    }
+                }
 
-                let opaque_type_key = ty::OpaqueTypeKey { def_id, args: opaque_ty.args };
-                let actual = self
-                    .register_hidden_type_in_storage(opaque_type_key, expected)
-                    .unwrap_or_else(|| {
-                        let actual =
-                            cx.type_of_opaque_hir_typeck(def_id).instantiate(cx, opaque_ty.args);
-                        let actual = fold_regions(cx, actual, |re, _dbi| match re.kind() {
-                            ty::ReErased => self.next_region_var(),
-                            _ => re,
-                        });
-                        actual
-                    });
-                self.eq(goal.param_env, expected, actual)?;
                 self.add_item_bounds_for_hidden_type(
                     def_id.into(),
-                    opaque_ty.args,
+                    normalized_args,
                     goal.param_env,
                     expected,
                 );
@@ -168,44 +135,3 @@ where
         }
     }
 }
-
-/// Checks whether each generic argument is simply a unique generic placeholder.
-///
-/// FIXME: Interner argument is needed to constrain the `I` parameter.
-fn uses_unique_placeholders_ignoring_regions<I: Interner>(
-    _cx: I,
-    args: I::GenericArgs,
-) -> Result<(), NotUniqueParam<I>> {
-    let mut seen = GrowableBitSet::default();
-    for arg in args.iter() {
-        match arg.kind() {
-            // Ignore regions, since we can't resolve those in a canonicalized
-            // query in the trait solver.
-            ty::GenericArgKind::Lifetime(_) => {}
-            ty::GenericArgKind::Type(t) => match t.kind() {
-                ty::Placeholder(p) => {
-                    if !seen.insert(p.var()) {
-                        return Err(NotUniqueParam::DuplicateParam(t.into()));
-                    }
-                }
-                _ => return Err(NotUniqueParam::NotParam(t.into())),
-            },
-            ty::GenericArgKind::Const(c) => match c.kind() {
-                ty::ConstKind::Placeholder(p) => {
-                    if !seen.insert(p.var()) {
-                        return Err(NotUniqueParam::DuplicateParam(c.into()));
-                    }
-                }
-                _ => return Err(NotUniqueParam::NotParam(c.into())),
-            },
-        }
-    }
-
-    Ok(())
-}
-
-// FIXME: This should check for dupes and non-params first, then infer vars.
-enum NotUniqueParam<I: Interner> {
-    DuplicateParam(I::GenericArg),
-    NotParam(I::GenericArg),
-}
diff --git a/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs b/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs
index 60bae738e61..891ecab041a 100644
--- a/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/trait_goals.rs
@@ -6,18 +6,20 @@ use rustc_type_ir::inherent::*;
 use rustc_type_ir::lang_items::TraitSolverLangItem;
 use rustc_type_ir::solve::{CanonicalResponse, SizedTraitKind};
 use rustc_type_ir::{
-    self as ty, Interner, Movability, TraitPredicate, TraitRef, TypeVisitableExt as _, TypingMode,
-    Upcast as _, elaborate,
+    self as ty, Interner, Movability, PredicatePolarity, TraitPredicate, TraitRef,
+    TypeVisitableExt as _, TypingMode, Upcast as _, elaborate,
 };
 use tracing::{debug, instrument, trace};
 
 use crate::delegate::SolverDelegate;
 use crate::solve::assembly::structural_traits::{self, AsyncCallableRelevantTypes};
-use crate::solve::assembly::{self, AllowInferenceConstraints, AssembleCandidatesFrom, Candidate};
+use crate::solve::assembly::{
+    self, AllowInferenceConstraints, AssembleCandidatesFrom, Candidate, FailedCandidateInfo,
+};
 use crate::solve::inspect::ProbeKind;
 use crate::solve::{
     BuiltinImplSource, CandidateSource, Certainty, EvalCtxt, Goal, GoalSource, MaybeCause,
-    NoSolution, ParamEnvSource, QueryResult, has_only_region_constraints,
+    MergeCandidateInfo, NoSolution, ParamEnvSource, QueryResult, has_only_region_constraints,
 };
 
 impl<D, I> assembly::GoalKind<D> for TraitPredicate<I>
@@ -131,19 +133,26 @@ where
             cx: I,
             clause_def_id: I::DefId,
             goal_def_id: I::DefId,
+            polarity: PredicatePolarity,
         ) -> bool {
             clause_def_id == goal_def_id
             // PERF(sized-hierarchy): Sizedness supertraits aren't elaborated to improve perf, so
             // check for a `MetaSized` supertrait being matched against a `Sized` assumption.
             //
             // `PointeeSized` bounds are syntactic sugar for a lack of bounds so don't need this.
-                || (cx.is_lang_item(clause_def_id, TraitSolverLangItem::Sized)
+                || (polarity == PredicatePolarity::Positive
+                    && cx.is_lang_item(clause_def_id, TraitSolverLangItem::Sized)
                     && cx.is_lang_item(goal_def_id, TraitSolverLangItem::MetaSized))
         }
 
         if let Some(trait_clause) = assumption.as_trait_clause()
             && trait_clause.polarity() == goal.predicate.polarity
-            && trait_def_id_matches(ecx.cx(), trait_clause.def_id(), goal.predicate.def_id())
+            && trait_def_id_matches(
+                ecx.cx(),
+                trait_clause.def_id(),
+                goal.predicate.def_id(),
+                goal.predicate.polarity,
+            )
             && DeepRejectCtxt::relate_rigid_rigid(ecx.cx()).args_may_unify(
                 goal.predicate.trait_ref.args,
                 trait_clause.skip_binder().trait_ref.args,
@@ -166,6 +175,8 @@ where
         // PERF(sized-hierarchy): Sizedness supertraits aren't elaborated to improve perf, so
         // check for a `Sized` subtrait when looking for `MetaSized`. `PointeeSized` bounds
         // are syntactic sugar for a lack of bounds so don't need this.
+        // We don't need to check polarity, `fast_reject_assumption` already rejected non-`Positive`
+        // polarity `Sized` assumptions as matching non-`Positive` `MetaSized` goals.
         if ecx.cx().is_lang_item(goal.predicate.def_id(), TraitSolverLangItem::MetaSized)
             && ecx.cx().is_lang_item(trait_clause.def_id(), TraitSolverLangItem::Sized)
         {
@@ -1344,9 +1355,10 @@ where
     pub(super) fn merge_trait_candidates(
         &mut self,
         mut candidates: Vec<Candidate<I>>,
+        failed_candidate_info: FailedCandidateInfo,
     ) -> Result<(CanonicalResponse<I>, Option<TraitGoalProvenVia>), NoSolution> {
         if let TypingMode::Coherence = self.typing_mode() {
-            return if let Some(response) = self.try_merge_candidates(&candidates) {
+            return if let Some((response, _)) = self.try_merge_candidates(&candidates) {
                 Ok((response, Some(TraitGoalProvenVia::Misc)))
             } else {
                 self.flounder(&candidates).map(|r| (r, None))
@@ -1376,10 +1388,41 @@ where
             let where_bounds: Vec<_> = candidates
                 .extract_if(.., |c| matches!(c.source, CandidateSource::ParamEnv(_)))
                 .collect();
-            return if let Some(response) = self.try_merge_candidates(&where_bounds) {
-                Ok((response, Some(TraitGoalProvenVia::ParamEnv)))
+            if let Some((response, info)) = self.try_merge_candidates(&where_bounds) {
+                match info {
+                    // If there's an always applicable candidate, the result of all
+                    // other candidates does not matter. This means we can ignore
+                    // them when checking whether we've reached a fixpoint.
+                    //
+                    // We always prefer the first always applicable candidate, even if a
+                    // later candidate is also always applicable and would result in fewer
+                    // reruns. We could slightly improve this by e.g. searching for another
+                    // always applicable candidate which doesn't depend on any cycle heads.
+                    //
+                    // NOTE: This is optimization is observable in case there is an always
+                    // applicable global candidate and another non-global candidate which only
+                    // applies because of a provisional result. I can't even think of a test
+                    // case where this would occur and even then, this would not be unsound.
+                    // Supporting this makes the code more involved, so I am just going to
+                    // ignore this for now.
+                    MergeCandidateInfo::AlwaysApplicable(i) => {
+                        for (j, c) in where_bounds.into_iter().enumerate() {
+                            if i != j {
+                                self.ignore_candidate_head_usages(c.head_usages)
+                            }
+                        }
+                        // If a where-bound does not apply, we don't actually get a
+                        // candidate for it. We manually track the head usages
+                        // of all failed `ParamEnv` candidates instead.
+                        self.ignore_candidate_head_usages(
+                            failed_candidate_info.param_env_head_usages,
+                        );
+                    }
+                    MergeCandidateInfo::EqualResponse => {}
+                }
+                return Ok((response, Some(TraitGoalProvenVia::ParamEnv)));
             } else {
-                Ok((self.bail_with_ambiguity(&where_bounds), None))
+                return Ok((self.bail_with_ambiguity(&where_bounds), None));
             };
         }
 
@@ -1387,7 +1430,7 @@ where
             let alias_bounds: Vec<_> = candidates
                 .extract_if(.., |c| matches!(c.source, CandidateSource::AliasBound))
                 .collect();
-            return if let Some(response) = self.try_merge_candidates(&alias_bounds) {
+            return if let Some((response, _)) = self.try_merge_candidates(&alias_bounds) {
                 Ok((response, Some(TraitGoalProvenVia::AliasBound)))
             } else {
                 Ok((self.bail_with_ambiguity(&alias_bounds), None))
@@ -1412,7 +1455,7 @@ where
             TraitGoalProvenVia::Misc
         };
 
-        if let Some(response) = self.try_merge_candidates(&candidates) {
+        if let Some((response, _)) = self.try_merge_candidates(&candidates) {
             Ok((response, Some(proven_via)))
         } else {
             self.flounder(&candidates).map(|r| (r, None))
@@ -1424,8 +1467,9 @@ where
         &mut self,
         goal: Goal<I, TraitPredicate<I>>,
     ) -> Result<(CanonicalResponse<I>, Option<TraitGoalProvenVia>), NoSolution> {
-        let candidates = self.assemble_and_evaluate_candidates(goal, AssembleCandidatesFrom::All);
-        self.merge_trait_candidates(candidates)
+        let (candidates, failed_candidate_info) =
+            self.assemble_and_evaluate_candidates(goal, AssembleCandidatesFrom::All);
+        self.merge_trait_candidates(candidates, failed_candidate_info)
     }
 
     fn try_stall_coroutine(&mut self, self_ty: I::Ty) -> Option<Result<Candidate<I>, NoSolution>> {
diff --git a/compiler/rustc_parse/Cargo.toml b/compiler/rustc_parse/Cargo.toml
index 0ae0b613fa2..7cb4ae7ff5f 100644
--- a/compiler/rustc_parse/Cargo.toml
+++ b/compiler/rustc_parse/Cargo.toml
@@ -5,11 +5,10 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-bitflags = "2.4.1"
-rustc-literal-escaper = "0.0.5"
+bitflags.workspace = true
+rustc-literal-escaper.workspace = true
 rustc_ast = { path = "../rustc_ast" }
 rustc_ast_pretty = { path = "../rustc_ast_pretty" }
-rustc_attr_parsing = { path = "../rustc_attr_parsing" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
 rustc_feature = { path = "../rustc_feature" }
@@ -19,8 +18,8 @@ rustc_lexer = { path = "../rustc_lexer" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
-thin-vec = "0.2.12"
-tracing = "0.1"
+thin-vec.workspace = true
+tracing.workspace = true
 unicode-normalization = "0.1.11"
 unicode-width = "0.2.0"
 # tidy-alphabetical-end
diff --git a/compiler/rustc_parse/messages.ftl b/compiler/rustc_parse/messages.ftl
index 3a21eea3d0a..4ca2f57bd87 100644
--- a/compiler/rustc_parse/messages.ftl
+++ b/compiler/rustc_parse/messages.ftl
@@ -359,6 +359,20 @@ parse_generics_in_path = unexpected generic arguments in path
 
 parse_help_set_edition_cargo = set `edition = "{$edition}"` in `Cargo.toml`
 parse_help_set_edition_standalone = pass `--edition {$edition}` to `rustc`
+
+parse_hidden_unicode_codepoints = unicode codepoint changing visible direction of text present in {$label}
+    .label = this {$label} contains {$count ->
+        [one] an invisible
+        *[other] invisible
+    } unicode text flow control {$count ->
+        [one] codepoint
+        *[other] codepoints
+    }
+    .note = these kind of unicode codepoints change the way text flows on applications that support them, but can cause confusion because they change the order of characters on the screen
+    .suggestion_remove = if their presence wasn't intentional, you can remove them
+    .suggestion_escape = if you want to keep them but make them visible in your source code, you can escape them
+    .no_suggestion_note_escape = if you want to keep them but make them visible in your source code, you can escape them: {$escaped}
+
 parse_if_expression_missing_condition = missing condition for `if` expression
     .condition_label = expected condition here
     .block_label = if this block is the condition of the `if` expression, then it must be followed by another block
@@ -436,11 +450,6 @@ parse_inner_doc_comment_not_permitted = expected outer doc comment
     .label_does_not_annotate_this = the inner doc comment doesn't annotate this {$item}
     .sugg_change_inner_to_outer = to annotate the {$item}, change the doc comment from inner to outer style
 
-parse_invalid_attr_unsafe = `{$name}` is not an unsafe attribute
-    .label = this is not an unsafe attribute
-    .suggestion = remove the `unsafe(...)`
-    .note = extraneous unsafe is not allowed in attributes
-
 parse_invalid_block_macro_segment = cannot use a `block` macro fragment here
     .label = the `block` fragment is within this context
     .suggestion = wrap this in another block
@@ -468,9 +477,6 @@ parse_invalid_dyn_keyword = invalid `dyn` keyword
 parse_invalid_expression_in_let_else = a `{$operator}` expression cannot be directly assigned in `let...else`
 parse_invalid_identifier_with_leading_number = identifiers cannot start with a number
 
-parse_invalid_label =
-    invalid label name `{$name}`
-
 parse_invalid_literal_suffix_on_tuple_index = suffixes on a tuple index are invalid
     .label = invalid suffix `{$suffix}`
     .tuple_exception_line_1 = `{$suffix}` is *temporarily* accepted on tuple index fields as it was incorrectly accepted on stable for a few releases
@@ -500,6 +506,8 @@ parse_invalid_unicode_escape = invalid unicode character escape
 parse_invalid_variable_declaration =
     invalid variable declaration
 
+parse_keyword_label = labels cannot use keyword names
+
 parse_keyword_lifetime =
     lifetimes cannot use keyword names
 
@@ -601,7 +609,6 @@ parse_maybe_report_ambiguous_plus =
     ambiguous `+` in a type
     .suggestion = use parentheses to disambiguate
 
-parse_meta_bad_delim = wrong meta list delimiters
 parse_meta_bad_delim_suggestion = the delimiters should be `(` and `)`
 
 parse_mismatched_closing_delimiter = mismatched closing delimiter: `{$delimiter}`
@@ -748,9 +755,6 @@ parse_parentheses_with_struct_fields = invalid `struct` delimiters or `fn` call
     .suggestion_braces_for_struct = if `{$type}` is a struct, use braces as delimiters
     .suggestion_no_fields_for_fn = if `{$type}` is a function, use the arguments directly
 
-parse_parenthesized_lifetime = parenthesized lifetime bounds are not supported
-parse_parenthesized_lifetime_suggestion = remove the parentheses
-
 parse_path_double_colon = path separator must be a double colon
     .suggestion = use a double colon instead
 
@@ -862,8 +866,8 @@ parse_too_many_hashes = too many `#` symbols: raw strings may be delimited by up
 
 parse_too_short_hex_escape = numeric character escape is too short
 
-parse_trailing_vert_not_allowed = a trailing `|` is not allowed in an or-pattern
-    .suggestion = remove the `{$token}`
+parse_trailing_vert_not_allowed = a trailing `{$token}` is not allowed in an or-pattern
+parse_trailing_vert_not_allowed_suggestion = remove the `{$token}`
 
 parse_trait_alias_cannot_be_auto = trait aliases cannot be `auto`
 parse_trait_alias_cannot_be_const = trait aliases cannot be `const`
@@ -993,10 +997,6 @@ parse_unmatched_angle_brackets = {$num_extra_brackets ->
            *[other] remove extra angle brackets
         }
 
-parse_unsafe_attr_outside_unsafe = unsafe attribute used without unsafe
-    .label = usage of unsafe attribute
-parse_unsafe_attr_outside_unsafe_suggestion = wrap the attribute in `unsafe(...)`
-
 
 parse_unskipped_whitespace = whitespace symbol '{$ch}' is not skipped
     .label = {parse_unskipped_whitespace}
diff --git a/compiler/rustc_parse/src/errors.rs b/compiler/rustc_parse/src/errors.rs
index a07d0606fd0..797d4830c2f 100644
--- a/compiler/rustc_parse/src/errors.rs
+++ b/compiler/rustc_parse/src/errors.rs
@@ -8,8 +8,9 @@ use rustc_ast::{Path, Visibility};
 use rustc_errors::codes::*;
 use rustc_errors::{
     Applicability, Diag, DiagCtxtHandle, Diagnostic, EmissionGuarantee, Level, Subdiagnostic,
+    SuggestionStyle,
 };
-use rustc_macros::{Diagnostic, Subdiagnostic};
+use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
 use rustc_session::errors::ExprParenthesesNeeded;
 use rustc_span::edition::{Edition, LATEST_STABLE_EDITION};
 use rustc_span::{Ident, Span, Symbol};
@@ -2228,11 +2229,10 @@ pub(crate) struct KeywordLifetime {
 }
 
 #[derive(Diagnostic)]
-#[diag(parse_invalid_label)]
-pub(crate) struct InvalidLabel {
+#[diag(parse_keyword_label)]
+pub(crate) struct KeywordLabel {
     #[primary_span]
     pub span: Span,
-    pub name: Symbol,
 }
 
 #[derive(Diagnostic)]
@@ -2661,7 +2661,7 @@ pub(crate) enum TopLevelOrPatternNotAllowedSugg {
         parse_sugg_remove_leading_vert_in_pattern,
         code = "",
         applicability = "machine-applicable",
-        style = "verbose"
+        style = "tool-only"
     )]
     RemoveLeadingVert {
         #[primary_span]
@@ -2694,12 +2694,25 @@ pub(crate) struct UnexpectedVertVertInPattern {
     pub start: Option<Span>,
 }
 
+#[derive(Subdiagnostic)]
+#[suggestion(
+    parse_trailing_vert_not_allowed,
+    code = "",
+    applicability = "machine-applicable",
+    style = "tool-only"
+)]
+pub(crate) struct TrailingVertSuggestion {
+    #[primary_span]
+    pub span: Span,
+}
+
 #[derive(Diagnostic)]
 #[diag(parse_trailing_vert_not_allowed)]
 pub(crate) struct TrailingVertNotAllowed {
     #[primary_span]
-    #[suggestion(code = "", applicability = "machine-applicable", style = "verbose")]
     pub span: Span,
+    #[subdiagnostic]
+    pub suggestion: TrailingVertSuggestion,
     #[label(parse_label_while_parsing_or_pattern_here)]
     pub start: Option<Span>,
     pub token: Token,
@@ -3150,27 +3163,6 @@ pub(crate) struct ModifierLifetime {
     pub modifier: &'static str,
 }
 
-#[derive(Subdiagnostic)]
-#[multipart_suggestion(
-    parse_parenthesized_lifetime_suggestion,
-    applicability = "machine-applicable"
-)]
-pub(crate) struct RemoveParens {
-    #[suggestion_part(code = "")]
-    pub lo: Span,
-    #[suggestion_part(code = "")]
-    pub hi: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(parse_parenthesized_lifetime)]
-pub(crate) struct ParenthesizedLifetime {
-    #[primary_span]
-    pub span: Span,
-    #[subdiagnostic]
-    pub sugg: RemoveParens,
-}
-
 #[derive(Diagnostic)]
 #[diag(parse_underscore_literal_suffix)]
 pub(crate) struct UnderscoreLiteralSuffix {
@@ -3354,15 +3346,6 @@ pub(crate) struct KwBadCase<'a> {
 }
 
 #[derive(Diagnostic)]
-#[diag(parse_meta_bad_delim)]
-pub(crate) struct MetaBadDelim {
-    #[primary_span]
-    pub span: Span,
-    #[subdiagnostic]
-    pub sugg: MetaBadDelimSugg,
-}
-
-#[derive(Diagnostic)]
 #[diag(parse_cfg_attr_bad_delim)]
 pub(crate) struct CfgAttrBadDelim {
     #[primary_span]
@@ -3502,38 +3485,6 @@ pub(crate) struct DotDotRangeAttribute {
 }
 
 #[derive(Diagnostic)]
-#[diag(parse_invalid_attr_unsafe)]
-#[note]
-pub(crate) struct InvalidAttrUnsafe {
-    #[primary_span]
-    #[label]
-    pub span: Span,
-    pub name: Path,
-}
-
-#[derive(Diagnostic)]
-#[diag(parse_unsafe_attr_outside_unsafe)]
-pub(crate) struct UnsafeAttrOutsideUnsafe {
-    #[primary_span]
-    #[label]
-    pub span: Span,
-    #[subdiagnostic]
-    pub suggestion: UnsafeAttrOutsideUnsafeSuggestion,
-}
-
-#[derive(Subdiagnostic)]
-#[multipart_suggestion(
-    parse_unsafe_attr_outside_unsafe_suggestion,
-    applicability = "machine-applicable"
-)]
-pub(crate) struct UnsafeAttrOutsideUnsafeSuggestion {
-    #[suggestion_part(code = "unsafe(")]
-    pub left: Span,
-    #[suggestion_part(code = ")")]
-    pub right: Span,
-}
-
-#[derive(Diagnostic)]
 #[diag(parse_binder_before_modifiers)]
 pub(crate) struct BinderBeforeModifiers {
     #[primary_span]
@@ -3651,3 +3602,76 @@ pub(crate) struct ExpectedRegisterClassOrExplicitRegister {
     #[primary_span]
     pub(crate) span: Span,
 }
+
+#[derive(LintDiagnostic)]
+#[diag(parse_hidden_unicode_codepoints)]
+#[note]
+pub(crate) struct HiddenUnicodeCodepointsDiag {
+    pub label: String,
+    pub count: usize,
+    #[label]
+    pub span_label: Span,
+    #[subdiagnostic]
+    pub labels: Option<HiddenUnicodeCodepointsDiagLabels>,
+    #[subdiagnostic]
+    pub sub: HiddenUnicodeCodepointsDiagSub,
+}
+
+pub(crate) struct HiddenUnicodeCodepointsDiagLabels {
+    pub spans: Vec<(char, Span)>,
+}
+
+impl Subdiagnostic for HiddenUnicodeCodepointsDiagLabels {
+    fn add_to_diag<G: EmissionGuarantee>(self, diag: &mut Diag<'_, G>) {
+        for (c, span) in self.spans {
+            diag.span_label(span, format!("{c:?}"));
+        }
+    }
+}
+
+pub(crate) enum HiddenUnicodeCodepointsDiagSub {
+    Escape { spans: Vec<(char, Span)> },
+    NoEscape { spans: Vec<(char, Span)> },
+}
+
+// Used because of multiple multipart_suggestion and note
+impl Subdiagnostic for HiddenUnicodeCodepointsDiagSub {
+    fn add_to_diag<G: EmissionGuarantee>(self, diag: &mut Diag<'_, G>) {
+        match self {
+            HiddenUnicodeCodepointsDiagSub::Escape { spans } => {
+                diag.multipart_suggestion_with_style(
+                    fluent::parse_suggestion_remove,
+                    spans.iter().map(|(_, span)| (*span, "".to_string())).collect(),
+                    Applicability::MachineApplicable,
+                    SuggestionStyle::HideCodeAlways,
+                );
+                diag.multipart_suggestion(
+                    fluent::parse_suggestion_escape,
+                    spans
+                        .into_iter()
+                        .map(|(c, span)| {
+                            let c = format!("{c:?}");
+                            (span, c[1..c.len() - 1].to_string())
+                        })
+                        .collect(),
+                    Applicability::MachineApplicable,
+                );
+            }
+            HiddenUnicodeCodepointsDiagSub::NoEscape { spans } => {
+                // FIXME: in other suggestions we've reversed the inner spans of doc comments. We
+                // should do the same here to provide the same good suggestions as we do for
+                // literals above.
+                diag.arg(
+                    "escaped",
+                    spans
+                        .into_iter()
+                        .map(|(c, _)| format!("{c:?}"))
+                        .collect::<Vec<String>>()
+                        .join(", "),
+                );
+                diag.note(fluent::parse_suggestion_remove);
+                diag.note(fluent::parse_no_suggestion_note_escape);
+            }
+        }
+    }
+}
diff --git a/compiler/rustc_parse/src/lexer/mod.rs b/compiler/rustc_parse/src/lexer/mod.rs
index 85af5a615ae..9792240a548 100644
--- a/compiler/rustc_parse/src/lexer/mod.rs
+++ b/compiler/rustc_parse/src/lexer/mod.rs
@@ -49,6 +49,7 @@ pub(crate) fn lex_token_trees<'psess, 'src>(
     mut src: &'src str,
     mut start_pos: BytePos,
     override_span: Option<Span>,
+    frontmatter_allowed: FrontmatterAllowed,
 ) -> Result<TokenStream, Vec<Diag<'psess>>> {
     // Skip `#!`, if present.
     if let Some(shebang_len) = rustc_lexer::strip_shebang(src) {
@@ -56,7 +57,7 @@ pub(crate) fn lex_token_trees<'psess, 'src>(
         start_pos = start_pos + BytePos::from_usize(shebang_len);
     }
 
-    let cursor = Cursor::new(src, FrontmatterAllowed::Yes);
+    let cursor = Cursor::new(src, frontmatter_allowed);
     let mut lexer = Lexer {
         psess,
         start_pos,
@@ -542,21 +543,21 @@ impl<'psess, 'src> Lexer<'psess, 'src> {
             })
             .collect();
 
+        let label = label.to_string();
         let count = spans.len();
-        let labels = point_at_inner_spans.then_some(spans.clone());
+        let labels = point_at_inner_spans
+            .then_some(errors::HiddenUnicodeCodepointsDiagLabels { spans: spans.clone() });
+        let sub = if point_at_inner_spans && !spans.is_empty() {
+            errors::HiddenUnicodeCodepointsDiagSub::Escape { spans }
+        } else {
+            errors::HiddenUnicodeCodepointsDiagSub::NoEscape { spans }
+        };
 
         self.psess.buffer_lint(
             TEXT_DIRECTION_CODEPOINT_IN_LITERAL,
             span,
             ast::CRATE_NODE_ID,
-            BuiltinLintDiag::HiddenUnicodeCodepoints {
-                label: label.to_string(),
-                count,
-                span_label: span,
-                labels,
-                escape: point_at_inner_spans && !spans.is_empty(),
-                spans,
-            },
+            errors::HiddenUnicodeCodepointsDiag { label, count, span_label: span, labels, sub },
         );
     }
 
diff --git a/compiler/rustc_parse/src/lib.rs b/compiler/rustc_parse/src/lib.rs
index 2050c5f9608..48289b2e8ab 100644
--- a/compiler/rustc_parse/src/lib.rs
+++ b/compiler/rustc_parse/src/lib.rs
@@ -16,10 +16,11 @@ use std::str::Utf8Error;
 use std::sync::Arc;
 
 use rustc_ast as ast;
-use rustc_ast::tokenstream::TokenStream;
+use rustc_ast::tokenstream::{DelimSpan, TokenStream};
 use rustc_ast::{AttrItem, Attribute, MetaItemInner, token};
 use rustc_ast_pretty::pprust;
 use rustc_errors::{Diag, EmissionGuarantee, FatalError, PResult, pluralize};
+use rustc_lexer::FrontmatterAllowed;
 use rustc_session::parse::ParseSess;
 use rustc_span::source_map::SourceMap;
 use rustc_span::{FileName, SourceFile, Span};
@@ -30,8 +31,9 @@ pub const MACRO_ARGUMENTS: Option<&str> = Some("macro arguments");
 #[macro_use]
 pub mod parser;
 use parser::Parser;
+use rustc_ast::token::Delimiter;
+
 pub mod lexer;
-pub mod validate_attr;
 
 mod errors;
 
@@ -146,7 +148,7 @@ fn new_parser_from_source_file(
     source_file: Arc<SourceFile>,
 ) -> Result<Parser<'_>, Vec<Diag<'_>>> {
     let end_pos = source_file.end_position();
-    let stream = source_file_to_stream(psess, source_file, None)?;
+    let stream = source_file_to_stream(psess, source_file, None, FrontmatterAllowed::Yes)?;
     let mut parser = Parser::new(psess, stream, None);
     if parser.token == token::Eof {
         parser.token.span = Span::new(end_pos, end_pos, parser.token.span.ctxt(), None);
@@ -161,7 +163,9 @@ pub fn source_str_to_stream(
     override_span: Option<Span>,
 ) -> Result<TokenStream, Vec<Diag<'_>>> {
     let source_file = psess.source_map().new_source_file(name, source);
-    source_file_to_stream(psess, source_file, override_span)
+    // used mainly for `proc_macro` and the likes, not for our parsing purposes, so don't parse
+    // frontmatters as frontmatters.
+    source_file_to_stream(psess, source_file, override_span, FrontmatterAllowed::No)
 }
 
 /// Given a source file, produces a sequence of token trees. Returns any buffered errors from
@@ -170,6 +174,7 @@ fn source_file_to_stream<'psess>(
     psess: &'psess ParseSess,
     source_file: Arc<SourceFile>,
     override_span: Option<Span>,
+    frontmatter_allowed: FrontmatterAllowed,
 ) -> Result<TokenStream, Vec<Diag<'psess>>> {
     let src = source_file.src.as_ref().unwrap_or_else(|| {
         psess.dcx().bug(format!(
@@ -178,7 +183,13 @@ fn source_file_to_stream<'psess>(
         ));
     });
 
-    lexer::lex_token_trees(psess, src.as_str(), source_file.start_pos, override_span)
+    lexer::lex_token_trees(
+        psess,
+        src.as_str(),
+        source_file.start_pos,
+        override_span,
+        frontmatter_allowed,
+    )
 }
 
 /// Runs the given subparser `f` on the tokens of the given `attr`'s item.
@@ -225,7 +236,7 @@ pub fn parse_cfg_attr(
         ast::AttrArgs::Delimited(ast::DelimArgs { dspan, delim, ref tokens })
             if !tokens.is_empty() =>
         {
-            crate::validate_attr::check_cfg_attr_bad_delim(psess, dspan, delim);
+            check_cfg_attr_bad_delim(psess, dspan, delim);
             match parse_in(psess, tokens.clone(), "`cfg_attr` input", |p| p.parse_cfg_attr()) {
                 Ok(r) => return Some(r),
                 Err(e) => {
@@ -244,3 +255,13 @@ pub fn parse_cfg_attr(
     }
     None
 }
+
+fn check_cfg_attr_bad_delim(psess: &ParseSess, span: DelimSpan, delim: Delimiter) {
+    if let Delimiter::Parenthesis = delim {
+        return;
+    }
+    psess.dcx().emit_err(errors::CfgAttrBadDelim {
+        span: span.entire(),
+        sugg: errors::MetaBadDelimSugg { open: span.open, close: span.close },
+    });
+}
diff --git a/compiler/rustc_parse/src/parser/attr.rs b/compiler/rustc_parse/src/parser/attr.rs
index 41d3889c448..acd338156ce 100644
--- a/compiler/rustc_parse/src/parser/attr.rs
+++ b/compiler/rustc_parse/src/parser/attr.rs
@@ -11,6 +11,7 @@ use tracing::debug;
 use super::{
     AttrWrapper, Capturing, FnParseMode, ForceCollect, Parser, PathStyle, Trailing, UsePreAttrPos,
 };
+use crate::parser::FnContext;
 use crate::{errors, exp, fluent_generated as fluent};
 
 // Public for rustfmt usage
@@ -200,7 +201,7 @@ impl<'a> Parser<'a> {
             AttrWrapper::empty(),
             true,
             false,
-            FnParseMode { req_name: |_| true, req_body: true },
+            FnParseMode { req_name: |_| true, context: FnContext::Free, req_body: true },
             ForceCollect::No,
         ) {
             Ok(Some(item)) => {
@@ -398,7 +399,7 @@ impl<'a> Parser<'a> {
     }
 
     /// Matches `COMMASEP(meta_item_inner)`.
-    pub(crate) fn parse_meta_seq_top(&mut self) -> PResult<'a, ThinVec<ast::MetaItemInner>> {
+    pub fn parse_meta_seq_top(&mut self) -> PResult<'a, ThinVec<ast::MetaItemInner>> {
         // Presumably, the majority of the time there will only be one attr.
         let mut nmis = ThinVec::with_capacity(1);
         while self.token != token::Eof {
diff --git a/compiler/rustc_parse/src/parser/cfg_select.rs b/compiler/rustc_parse/src/parser/cfg_select.rs
index 2c6fb224d70..08a71db4de8 100644
--- a/compiler/rustc_parse/src/parser/cfg_select.rs
+++ b/compiler/rustc_parse/src/parser/cfg_select.rs
@@ -1,11 +1,12 @@
 use rustc_ast::token::Token;
 use rustc_ast::tokenstream::{TokenStream, TokenTree};
+use rustc_ast::util::classify;
 use rustc_ast::{MetaItemInner, token};
 use rustc_errors::PResult;
 use rustc_span::Span;
 
 use crate::exp;
-use crate::parser::Parser;
+use crate::parser::{AttrWrapper, ForceCollect, Parser, Restrictions, Trailing, UsePreAttrPos};
 
 pub enum CfgSelectPredicate {
     Cfg(MetaItemInner),
@@ -23,19 +24,26 @@ pub struct CfgSelectBranches {
     pub unreachable: Vec<(CfgSelectPredicate, TokenStream, Span)>,
 }
 
-/// Parses a `TokenTree` that must be of the form `{ /* ... */ }`, and returns a `TokenStream` where
-/// the surrounding braces are stripped.
+/// Parses a `TokenTree` consisting either of `{ /* ... */ }` (and strip the braces) or an
+/// expression followed by a comma (and strip the comma).
 fn parse_token_tree<'a>(p: &mut Parser<'a>) -> PResult<'a, TokenStream> {
-    // Generate an error if the `=>` is not followed by `{`.
-    if p.token != token::OpenBrace {
-        p.expect(exp!(OpenBrace))?;
+    if p.token == token::OpenBrace {
+        // Strip the outer '{' and '}'.
+        match p.parse_token_tree() {
+            TokenTree::Token(..) => unreachable!("because of the expect above"),
+            TokenTree::Delimited(.., tts) => return Ok(tts),
+        }
     }
-
-    // Strip the outer '{' and '}'.
-    match p.parse_token_tree() {
-        TokenTree::Token(..) => unreachable!("because of the expect above"),
-        TokenTree::Delimited(.., tts) => Ok(tts),
+    let expr = p.collect_tokens(None, AttrWrapper::empty(), ForceCollect::Yes, |p, _| {
+        p.parse_expr_res(Restrictions::STMT_EXPR, AttrWrapper::empty())
+            .map(|(expr, _)| (expr, Trailing::No, UsePreAttrPos::No))
+    })?;
+    if !classify::expr_is_complete(&expr) && p.token != token::CloseBrace && p.token != token::Eof {
+        p.expect(exp!(Comma))?;
+    } else {
+        let _ = p.eat(exp!(Comma));
     }
+    Ok(TokenStream::from_ast(&expr))
 }
 
 pub fn parse_cfg_select<'a>(p: &mut Parser<'a>) -> PResult<'a, CfgSelectBranches> {
diff --git a/compiler/rustc_parse/src/parser/diagnostics.rs b/compiler/rustc_parse/src/parser/diagnostics.rs
index a32cd33a260..a28af7833c3 100644
--- a/compiler/rustc_parse/src/parser/diagnostics.rs
+++ b/compiler/rustc_parse/src/parser/diagnostics.rs
@@ -44,6 +44,7 @@ use crate::errors::{
     UnexpectedConstParamDeclaration, UnexpectedConstParamDeclarationSugg, UnmatchedAngleBrackets,
     UseEqInstead, WrapType,
 };
+use crate::parser::FnContext;
 use crate::parser::attr::InnerAttrPolicy;
 use crate::{exp, fluent_generated as fluent};
 
@@ -462,8 +463,8 @@ impl<'a> Parser<'a> {
 
     pub(super) fn expected_one_of_not_found(
         &mut self,
-        edible: &[ExpTokenPair<'_>],
-        inedible: &[ExpTokenPair<'_>],
+        edible: &[ExpTokenPair],
+        inedible: &[ExpTokenPair],
     ) -> PResult<'a, ErrorGuaranteed> {
         debug!("expected_one_of_not_found(edible: {:?}, inedible: {:?})", edible, inedible);
         fn tokens_to_string(tokens: &[TokenType]) -> String {
@@ -1091,7 +1092,7 @@ impl<'a> Parser<'a> {
 
     /// Eats and discards tokens until one of `closes` is encountered. Respects token trees,
     /// passes through any errors encountered. Used for error recovery.
-    pub(super) fn eat_to_tokens(&mut self, closes: &[ExpTokenPair<'_>]) {
+    pub(super) fn eat_to_tokens(&mut self, closes: &[ExpTokenPair]) {
         if let Err(err) = self
             .parse_seq_to_before_tokens(closes, &[], SeqSep::none(), |p| Ok(p.parse_token_tree()))
         {
@@ -1112,7 +1113,7 @@ impl<'a> Parser<'a> {
     pub(super) fn check_trailing_angle_brackets(
         &mut self,
         segment: &PathSegment,
-        end: &[ExpTokenPair<'_>],
+        end: &[ExpTokenPair],
     ) -> Option<ErrorGuaranteed> {
         if !self.may_recover() {
             return None;
@@ -1195,7 +1196,7 @@ impl<'a> Parser<'a> {
         // second case.
         if self.look_ahead(position, |t| {
             trace!("check_trailing_angle_brackets: t={:?}", t);
-            end.iter().any(|exp| exp.tok == &t.kind)
+            end.iter().any(|exp| exp.tok == t.kind)
         }) {
             // Eat from where we started until the end token so that parsing can continue
             // as if we didn't have those extra angle brackets.
@@ -2119,8 +2120,8 @@ impl<'a> Parser<'a> {
 
     pub(super) fn recover_seq_parse_error(
         &mut self,
-        open: ExpTokenPair<'_>,
-        close: ExpTokenPair<'_>,
+        open: ExpTokenPair,
+        close: ExpTokenPair,
         lo: Span,
         err: Diag<'a>,
     ) -> Box<Expr> {
@@ -2246,6 +2247,7 @@ impl<'a> Parser<'a> {
         pat: Box<ast::Pat>,
         require_name: bool,
         first_param: bool,
+        fn_parse_mode: &crate::parser::item::FnParseMode,
     ) -> Option<Ident> {
         // If we find a pattern followed by an identifier, it could be an (incorrect)
         // C-style parameter declaration.
@@ -2268,7 +2270,14 @@ impl<'a> Parser<'a> {
                 || self.token == token::Lt
                 || self.token == token::CloseParen)
         {
-            let rfc_note = "anonymous parameters are removed in the 2018 edition (see RFC 1685)";
+            let maybe_emit_anon_params_note = |this: &mut Self, err: &mut Diag<'_>| {
+                let ed = this.token.span.with_neighbor(this.prev_token.span).edition();
+                if matches!(fn_parse_mode.context, crate::parser::item::FnContext::Trait)
+                    && (fn_parse_mode.req_name)(ed)
+                {
+                    err.note("anonymous parameters are removed in the 2018 edition (see RFC 1685)");
+                }
+            };
 
             let (ident, self_sugg, param_sugg, type_sugg, self_span, param_span, type_span) =
                 match pat.kind {
@@ -2305,7 +2314,7 @@ impl<'a> Parser<'a> {
                                 "_: ".to_string(),
                                 Applicability::MachineApplicable,
                             );
-                            err.note(rfc_note);
+                            maybe_emit_anon_params_note(self, err);
                         }
 
                         return None;
@@ -2313,7 +2322,13 @@ impl<'a> Parser<'a> {
                 };
 
             // `fn foo(a, b) {}`, `fn foo(a<x>, b<y>) {}` or `fn foo(usize, usize) {}`
-            if first_param {
+            if first_param
+                // Only when the fn is a method, we emit this suggestion.
+                && matches!(
+                    fn_parse_mode.context,
+                    FnContext::Trait | FnContext::Impl
+                )
+            {
                 err.span_suggestion_verbose(
                     self_span,
                     "if this is a `self` type, give it a parameter name",
@@ -2337,7 +2352,7 @@ impl<'a> Parser<'a> {
                 type_sugg,
                 Applicability::MachineApplicable,
             );
-            err.note(rfc_note);
+            maybe_emit_anon_params_note(self, err);
 
             // Don't attempt to recover by using the `X` in `X<Y>` as the parameter name.
             return if self.token == token::Lt { None } else { Some(ident) };
@@ -2371,8 +2386,8 @@ impl<'a> Parser<'a> {
 
     pub(super) fn consume_block(
         &mut self,
-        open: ExpTokenPair<'_>,
-        close: ExpTokenPair<'_>,
+        open: ExpTokenPair,
+        close: ExpTokenPair,
         consume_close: ConsumeClosingDelim,
     ) {
         let mut brace_depth = 0;
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index d0604f76317..f0f58e901a9 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -1598,7 +1598,7 @@ impl<'a> Parser<'a> {
         self.maybe_recover_from_bad_qpath(expr)
     }
 
-    fn parse_expr_array_or_repeat(&mut self, close: ExpTokenPair<'_>) -> PResult<'a, Box<Expr>> {
+    fn parse_expr_array_or_repeat(&mut self, close: ExpTokenPair) -> PResult<'a, Box<Expr>> {
         let lo = self.token.span;
         self.bump(); // `[` or other open delim
 
@@ -2077,7 +2077,7 @@ impl<'a> Parser<'a> {
         (token::Lit { symbol: name, suffix: None, kind: token::Char }, span)
     }
 
-    fn mk_meta_item_lit_char(name: Symbol, span: Span) -> MetaItemLit {
+    pub fn mk_meta_item_lit_char(name: Symbol, span: Span) -> MetaItemLit {
         ast::MetaItemLit {
             symbol: name,
             suffix: None,
@@ -2086,7 +2086,7 @@ impl<'a> Parser<'a> {
         }
     }
 
-    fn handle_missing_lit<L>(
+    pub fn handle_missing_lit<L>(
         &mut self,
         mk_lit_char: impl FnOnce(Symbol, Span) -> L,
     ) -> PResult<'a, L> {
@@ -2156,7 +2156,7 @@ impl<'a> Parser<'a> {
 
     /// Keep this in sync with `Token::can_begin_literal_maybe_minus` and
     /// `Lit::from_token` (excluding unary negation).
-    fn eat_token_lit(&mut self) -> Option<token::Lit> {
+    pub fn eat_token_lit(&mut self) -> Option<token::Lit> {
         let check_expr = |expr: Box<Expr>| {
             if let ast::ExprKind::Lit(token_lit) = expr.kind {
                 Some(token_lit)
@@ -2397,20 +2397,24 @@ impl<'a> Parser<'a> {
         let before = self.prev_token;
         let binder = if self.check_keyword(exp!(For)) {
             let lo = self.token.span;
-            let (lifetime_defs, _) = self.parse_late_bound_lifetime_defs()?;
+            let (bound_vars, _) = self.parse_higher_ranked_binder()?;
             let span = lo.to(self.prev_token.span);
 
             self.psess.gated_spans.gate(sym::closure_lifetime_binder, span);
 
-            ClosureBinder::For { span, generic_params: lifetime_defs }
+            ClosureBinder::For { span, generic_params: bound_vars }
         } else {
             ClosureBinder::NotPresent
         };
 
         let constness = self.parse_closure_constness();
 
-        let movability =
-            if self.eat_keyword(exp!(Static)) { Movability::Static } else { Movability::Movable };
+        let movability = if self.eat_keyword(exp!(Static)) {
+            self.psess.gated_spans.gate(sym::coroutines, self.prev_token.span);
+            Movability::Static
+        } else {
+            Movability::Movable
+        };
 
         let coroutine_kind = if self.token_uninterpolated_span().at_least_rust_2018() {
             self.parse_coroutine_kind(Case::Sensitive)
@@ -3090,7 +3094,7 @@ impl<'a> Parser<'a> {
         if let Some((ident, is_raw)) = self.token.lifetime() {
             // Disallow `'fn`, but with a better error message than `expect_lifetime`.
             if matches!(is_raw, IdentIsRaw::No) && ident.without_first_quote().is_reserved() {
-                self.dcx().emit_err(errors::InvalidLabel { span: ident.span, name: ident.name });
+                self.dcx().emit_err(errors::KeywordLabel { span: ident.span });
             }
 
             self.bump();
@@ -3657,7 +3661,7 @@ impl<'a> Parser<'a> {
         &mut self,
         pth: ast::Path,
         recover: bool,
-        close: ExpTokenPair<'_>,
+        close: ExpTokenPair,
     ) -> PResult<
         'a,
         (
@@ -3676,8 +3680,8 @@ impl<'a> Parser<'a> {
             errors::HelpUseLatestEdition::new().add_to_diag(e);
         };
 
-        while self.token != *close.tok {
-            if self.eat(exp!(DotDot)) || self.recover_struct_field_dots(close.tok) {
+        while self.token != close.tok {
+            if self.eat(exp!(DotDot)) || self.recover_struct_field_dots(&close.tok) {
                 let exp_span = self.prev_token.span;
                 // We permit `.. }` on the left-hand side of a destructuring assignment.
                 if self.check(close) {
diff --git a/compiler/rustc_parse/src/parser/generics.rs b/compiler/rustc_parse/src/parser/generics.rs
index 4a8530a2b38..eb684c3a62f 100644
--- a/compiler/rustc_parse/src/parser/generics.rs
+++ b/compiler/rustc_parse/src/parser/generics.rs
@@ -172,8 +172,11 @@ impl<'a> Parser<'a> {
         })
     }
 
-    /// Parses a (possibly empty) list of lifetime and type parameters, possibly including
-    /// a trailing comma and erroneous trailing attributes.
+    /// Parse a (possibly empty) list of generic (lifetime, type, const) parameters.
+    ///
+    /// ```ebnf
+    /// GenericParams = (GenericParam ("," GenericParam)* ","?)?
+    /// ```
     pub(super) fn parse_generic_params(&mut self) -> PResult<'a, ThinVec<ast::GenericParam>> {
         let mut params = ThinVec::new();
         let mut done = false;
@@ -520,7 +523,7 @@ impl<'a> Parser<'a> {
         // * `for<'a> Trait1<'a>: Trait2<'a /* ok */>`
         // * `(for<'a> Trait1<'a>): Trait2<'a /* not ok */>`
         // * `for<'a> for<'b> Trait1<'a, 'b>: Trait2<'a /* ok */, 'b /* not ok */>`
-        let (lifetime_defs, _) = self.parse_late_bound_lifetime_defs()?;
+        let (bound_vars, _) = self.parse_higher_ranked_binder()?;
 
         // Parse type with mandatory colon and (possibly empty) bounds,
         // or with mandatory equality sign and the second type.
@@ -528,7 +531,7 @@ impl<'a> Parser<'a> {
         if self.eat(exp!(Colon)) {
             let bounds = self.parse_generic_bounds()?;
             Ok(ast::WherePredicateKind::BoundPredicate(ast::WhereBoundPredicate {
-                bound_generic_params: lifetime_defs,
+                bound_generic_params: bound_vars,
                 bounded_ty: ty,
                 bounds,
             }))
diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs
index 607adaf0829..eb264f59fed 100644
--- a/compiler/rustc_parse/src/parser/item.rs
+++ b/compiler/rustc_parse/src/parser/item.rs
@@ -43,7 +43,7 @@ impl<'a> Parser<'a> {
             self.expect(exp!(OpenBrace))?;
             let (inner_attrs, items, inner_span) = self.parse_mod(exp!(CloseBrace))?;
             attrs.extend(inner_attrs);
-            ModKind::Loaded(items, Inline::Yes, inner_span, Ok(()))
+            ModKind::Loaded(items, Inline::Yes, inner_span)
         };
         Ok(ItemKind::Mod(safety, ident, mod_kind))
     }
@@ -54,7 +54,7 @@ impl<'a> Parser<'a> {
     /// - `}` for mod items
     pub fn parse_mod(
         &mut self,
-        term: ExpTokenPair<'_>,
+        term: ExpTokenPair,
     ) -> PResult<'a, (AttrVec, ThinVec<Box<Item>>, ModSpans)> {
         let lo = self.token.span;
         let attrs = self.parse_inner_attributes()?;
@@ -116,7 +116,8 @@ impl<'a> Parser<'a> {
 
 impl<'a> Parser<'a> {
     pub fn parse_item(&mut self, force_collect: ForceCollect) -> PResult<'a, Option<Box<Item>>> {
-        let fn_parse_mode = FnParseMode { req_name: |_| true, req_body: true };
+        let fn_parse_mode =
+            FnParseMode { req_name: |_| true, context: FnContext::Free, req_body: true };
         self.parse_item_(fn_parse_mode, force_collect).map(|i| i.map(Box::new))
     }
 
@@ -975,7 +976,8 @@ impl<'a> Parser<'a> {
         &mut self,
         force_collect: ForceCollect,
     ) -> PResult<'a, Option<Option<Box<AssocItem>>>> {
-        let fn_parse_mode = FnParseMode { req_name: |_| true, req_body: true };
+        let fn_parse_mode =
+            FnParseMode { req_name: |_| true, context: FnContext::Impl, req_body: true };
         self.parse_assoc_item(fn_parse_mode, force_collect)
     }
 
@@ -983,8 +985,11 @@ impl<'a> Parser<'a> {
         &mut self,
         force_collect: ForceCollect,
     ) -> PResult<'a, Option<Option<Box<AssocItem>>>> {
-        let fn_parse_mode =
-            FnParseMode { req_name: |edition| edition >= Edition::Edition2018, req_body: false };
+        let fn_parse_mode = FnParseMode {
+            req_name: |edition| edition >= Edition::Edition2018,
+            context: FnContext::Trait,
+            req_body: false,
+        };
         self.parse_assoc_item(fn_parse_mode, force_collect)
     }
 
@@ -1196,7 +1201,7 @@ impl<'a> Parser<'a> {
         }?;
 
         let dash = exp!(Minus);
-        if self.token != *dash.tok {
+        if self.token != dash.tok {
             return Ok(ident);
         }
 
@@ -1261,7 +1266,8 @@ impl<'a> Parser<'a> {
         &mut self,
         force_collect: ForceCollect,
     ) -> PResult<'a, Option<Option<Box<ForeignItem>>>> {
-        let fn_parse_mode = FnParseMode { req_name: |_| true, req_body: false };
+        let fn_parse_mode =
+            FnParseMode { req_name: |_| true, context: FnContext::Free, req_body: false };
         Ok(self.parse_item_(fn_parse_mode, force_collect)?.map(
             |Item { attrs, id, span, vis, kind, tokens }| {
                 let kind = match ForeignItemKind::try_from(kind) {
@@ -2135,7 +2141,8 @@ impl<'a> Parser<'a> {
                 let inherited_vis =
                     Visibility { span: DUMMY_SP, kind: VisibilityKind::Inherited, tokens: None };
                 // We use `parse_fn` to get a span for the function
-                let fn_parse_mode = FnParseMode { req_name: |_| true, req_body: true };
+                let fn_parse_mode =
+                    FnParseMode { req_name: |_| true, context: FnContext::Free, req_body: true };
                 match self.parse_fn(
                     &mut AttrVec::new(),
                     fn_parse_mode,
@@ -2403,6 +2410,9 @@ pub(crate) struct FnParseMode {
     ///   * The span is from Edition 2015. In particular, you can get a
     ///     2015 span inside a 2021 crate using macros.
     pub(super) req_name: ReqName,
+    /// The context in which this function is parsed, used for diagnostics.
+    /// This indicates the fn is a free function or method and so on.
+    pub(super) context: FnContext,
     /// If this flag is set to `true`, then plain, semicolon-terminated function
     /// prototypes are not allowed here.
     ///
@@ -2424,6 +2434,18 @@ pub(crate) struct FnParseMode {
     pub(super) req_body: bool,
 }
 
+/// The context in which a function is parsed.
+/// FIXME(estebank, xizheyin): Use more variants.
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub(crate) enum FnContext {
+    /// Free context.
+    Free,
+    /// A Trait context.
+    Trait,
+    /// An Impl block.
+    Impl,
+}
+
 /// Parsing of functions and methods.
 impl<'a> Parser<'a> {
     /// Parse a function starting from the front matter (`const ...`) to the body `{ ... }` or `;`.
@@ -2439,11 +2461,8 @@ impl<'a> Parser<'a> {
         let header = self.parse_fn_front_matter(vis, case, FrontMatterParsingMode::Function)?; // `const ... fn`
         let ident = self.parse_ident()?; // `foo`
         let mut generics = self.parse_generics()?; // `<'a, T, ...>`
-        let decl = match self.parse_fn_decl(
-            fn_parse_mode.req_name,
-            AllowPlus::Yes,
-            RecoverReturnSign::Yes,
-        ) {
+        let decl = match self.parse_fn_decl(&fn_parse_mode, AllowPlus::Yes, RecoverReturnSign::Yes)
+        {
             Ok(decl) => decl,
             Err(old_err) => {
                 // If we see `for Ty ...` then user probably meant `impl` item.
@@ -2961,18 +2980,21 @@ impl<'a> Parser<'a> {
     /// Parses the parameter list and result type of a function declaration.
     pub(super) fn parse_fn_decl(
         &mut self,
-        req_name: ReqName,
+        fn_parse_mode: &FnParseMode,
         ret_allow_plus: AllowPlus,
         recover_return_sign: RecoverReturnSign,
     ) -> PResult<'a, Box<FnDecl>> {
         Ok(Box::new(FnDecl {
-            inputs: self.parse_fn_params(req_name)?,
+            inputs: self.parse_fn_params(fn_parse_mode)?,
             output: self.parse_ret_ty(ret_allow_plus, RecoverQPath::Yes, recover_return_sign)?,
         }))
     }
 
     /// Parses the parameter list of a function, including the `(` and `)` delimiters.
-    pub(super) fn parse_fn_params(&mut self, req_name: ReqName) -> PResult<'a, ThinVec<Param>> {
+    pub(super) fn parse_fn_params(
+        &mut self,
+        fn_parse_mode: &FnParseMode,
+    ) -> PResult<'a, ThinVec<Param>> {
         let mut first_param = true;
         // Parse the arguments, starting out with `self` being allowed...
         if self.token != TokenKind::OpenParen
@@ -2988,7 +3010,7 @@ impl<'a> Parser<'a> {
         let (mut params, _) = self.parse_paren_comma_seq(|p| {
             p.recover_vcs_conflict_marker();
             let snapshot = p.create_snapshot_for_diagnostic();
-            let param = p.parse_param_general(req_name, first_param, true).or_else(|e| {
+            let param = p.parse_param_general(fn_parse_mode, first_param, true).or_else(|e| {
                 let guar = e.emit();
                 // When parsing a param failed, we should check to make the span of the param
                 // not contain '(' before it.
@@ -3019,7 +3041,7 @@ impl<'a> Parser<'a> {
     /// - `recover_arg_parse` is used to recover from a failed argument parse.
     pub(super) fn parse_param_general(
         &mut self,
-        req_name: ReqName,
+        fn_parse_mode: &FnParseMode,
         first_param: bool,
         recover_arg_parse: bool,
     ) -> PResult<'a, Param> {
@@ -3035,16 +3057,22 @@ impl<'a> Parser<'a> {
 
             let is_name_required = match this.token.kind {
                 token::DotDotDot => false,
-                _ => req_name(this.token.span.with_neighbor(this.prev_token.span).edition()),
+                _ => (fn_parse_mode.req_name)(
+                    this.token.span.with_neighbor(this.prev_token.span).edition(),
+                ),
             };
             let (pat, ty) = if is_name_required || this.is_named_param() {
                 debug!("parse_param_general parse_pat (is_name_required:{})", is_name_required);
                 let (pat, colon) = this.parse_fn_param_pat_colon()?;
                 if !colon {
                     let mut err = this.unexpected().unwrap_err();
-                    return if let Some(ident) =
-                        this.parameter_without_type(&mut err, pat, is_name_required, first_param)
-                    {
+                    return if let Some(ident) = this.parameter_without_type(
+                        &mut err,
+                        pat,
+                        is_name_required,
+                        first_param,
+                        fn_parse_mode,
+                    ) {
                         let guar = err.emit();
                         Ok((dummy_arg(ident, guar), Trailing::No, UsePreAttrPos::No))
                     } else {
diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs
index 0a8a0203013..15598f32429 100644
--- a/compiler/rustc_parse/src/parser/mod.rs
+++ b/compiler/rustc_parse/src/parser/mod.rs
@@ -22,9 +22,9 @@ use std::{fmt, mem, slice};
 use attr_wrapper::{AttrWrapper, UsePreAttrPos};
 pub use diagnostics::AttemptLocalParseRecovery;
 pub(crate) use expr::ForbiddenLetReason;
-pub(crate) use item::FnParseMode;
+pub(crate) use item::{FnContext, FnParseMode};
 pub use pat::{CommaRecoveryMode, RecoverColon, RecoverComma};
-use path::PathStyle;
+pub use path::PathStyle;
 use rustc_ast::token::{
     self, IdentIsRaw, InvisibleOrigin, MetaVarKind, NtExprKind, NtPatKind, Token, TokenKind,
 };
@@ -261,19 +261,19 @@ struct CaptureState {
 
 /// A sequence separator.
 #[derive(Debug)]
-struct SeqSep<'a> {
+struct SeqSep {
     /// The separator token.
-    sep: Option<ExpTokenPair<'a>>,
+    sep: Option<ExpTokenPair>,
     /// `true` if a trailing separator is allowed.
     trailing_sep_allowed: bool,
 }
 
-impl<'a> SeqSep<'a> {
-    fn trailing_allowed(sep: ExpTokenPair<'a>) -> SeqSep<'a> {
+impl SeqSep {
+    fn trailing_allowed(sep: ExpTokenPair) -> SeqSep {
         SeqSep { sep: Some(sep), trailing_sep_allowed: true }
     }
 
-    fn none() -> SeqSep<'a> {
+    fn none() -> SeqSep {
         SeqSep { sep: None, trailing_sep_allowed: false }
     }
 }
@@ -285,7 +285,7 @@ pub enum FollowedByType {
 }
 
 #[derive(Copy, Clone, Debug)]
-enum Trailing {
+pub enum Trailing {
     No,
     Yes,
 }
@@ -425,13 +425,13 @@ impl<'a> Parser<'a> {
     }
 
     /// Expects and consumes the token `t`. Signals an error if the next token is not `t`.
-    pub fn expect(&mut self, exp: ExpTokenPair<'_>) -> PResult<'a, Recovered> {
+    pub fn expect(&mut self, exp: ExpTokenPair) -> PResult<'a, Recovered> {
         if self.expected_token_types.is_empty() {
-            if self.token == *exp.tok {
+            if self.token == exp.tok {
                 self.bump();
                 Ok(Recovered::No)
             } else {
-                self.unexpected_try_recover(exp.tok)
+                self.unexpected_try_recover(&exp.tok)
             }
         } else {
             self.expect_one_of(slice::from_ref(&exp), &[])
@@ -443,13 +443,13 @@ impl<'a> Parser<'a> {
     /// anything. Signal a fatal error if next token is unexpected.
     fn expect_one_of(
         &mut self,
-        edible: &[ExpTokenPair<'_>],
-        inedible: &[ExpTokenPair<'_>],
+        edible: &[ExpTokenPair],
+        inedible: &[ExpTokenPair],
     ) -> PResult<'a, Recovered> {
-        if edible.iter().any(|exp| exp.tok == &self.token.kind) {
+        if edible.iter().any(|exp| exp.tok == self.token.kind) {
             self.bump();
             Ok(Recovered::No)
-        } else if inedible.iter().any(|exp| exp.tok == &self.token.kind) {
+        } else if inedible.iter().any(|exp| exp.tok == self.token.kind) {
             // leave it in the input
             Ok(Recovered::No)
         } else if self.token != token::Eof
@@ -494,8 +494,8 @@ impl<'a> Parser<'a> {
     /// This method will automatically add `tok` to `expected_token_types` if `tok` is not
     /// encountered.
     #[inline]
-    fn check(&mut self, exp: ExpTokenPair<'_>) -> bool {
-        let is_present = self.token == *exp.tok;
+    pub fn check(&mut self, exp: ExpTokenPair) -> bool {
+        let is_present = self.token == exp.tok;
         if !is_present {
             self.expected_token_types.insert(exp.token_type);
         }
@@ -542,7 +542,7 @@ impl<'a> Parser<'a> {
     /// Consumes a token 'tok' if it exists. Returns whether the given token was present.
     #[inline]
     #[must_use]
-    pub fn eat(&mut self, exp: ExpTokenPair<'_>) -> bool {
+    pub fn eat(&mut self, exp: ExpTokenPair) -> bool {
         let is_present = self.check(exp);
         if is_present {
             self.bump()
@@ -633,7 +633,7 @@ impl<'a> Parser<'a> {
     }
 
     /// Consume a sequence produced by a metavar expansion, if present.
-    fn eat_metavar_seq<T>(
+    pub fn eat_metavar_seq<T>(
         &mut self,
         mv_kind: MetaVarKind,
         f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
@@ -745,13 +745,13 @@ impl<'a> Parser<'a> {
     /// Eats the expected token if it's present possibly breaking
     /// compound tokens like multi-character operators in process.
     /// Returns `true` if the token was eaten.
-    fn break_and_eat(&mut self, exp: ExpTokenPair<'_>) -> bool {
-        if self.token == *exp.tok {
+    fn break_and_eat(&mut self, exp: ExpTokenPair) -> bool {
+        if self.token == exp.tok {
             self.bump();
             return true;
         }
         match self.token.kind.break_two_token_op(1) {
-            Some((first, second)) if first == *exp.tok => {
+            Some((first, second)) if first == exp.tok => {
                 let first_span = self.psess.source_map().start_point(self.token.span);
                 let second_span = self.token.span.with_lo(first_span.hi());
                 self.token = Token::new(first, first_span);
@@ -826,7 +826,7 @@ impl<'a> Parser<'a> {
     /// Checks if the next token is contained within `closes`, and returns `true` if so.
     fn expect_any_with_type(
         &mut self,
-        closes_expected: &[ExpTokenPair<'_>],
+        closes_expected: &[ExpTokenPair],
         closes_not_expected: &[&TokenKind],
     ) -> bool {
         closes_expected.iter().any(|&close| self.check(close))
@@ -838,9 +838,9 @@ impl<'a> Parser<'a> {
     /// closing bracket.
     fn parse_seq_to_before_tokens<T>(
         &mut self,
-        closes_expected: &[ExpTokenPair<'_>],
+        closes_expected: &[ExpTokenPair],
         closes_not_expected: &[&TokenKind],
-        sep: SeqSep<'_>,
+        sep: SeqSep,
         mut f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
     ) -> PResult<'a, (ThinVec<T>, Trailing, Recovered)> {
         let mut first = true;
@@ -869,7 +869,7 @@ impl<'a> Parser<'a> {
                         }
                         Err(mut expect_err) => {
                             let sp = self.prev_token.span.shrink_to_hi();
-                            let token_str = pprust::token_kind_to_string(exp.tok);
+                            let token_str = pprust::token_kind_to_string(&exp.tok);
 
                             match self.current_closure.take() {
                                 Some(closure_spans) if self.token == TokenKind::Semi => {
@@ -1039,8 +1039,8 @@ impl<'a> Parser<'a> {
     /// closing bracket.
     fn parse_seq_to_before_end<T>(
         &mut self,
-        close: ExpTokenPair<'_>,
-        sep: SeqSep<'_>,
+        close: ExpTokenPair,
+        sep: SeqSep,
         f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
     ) -> PResult<'a, (ThinVec<T>, Trailing, Recovered)> {
         self.parse_seq_to_before_tokens(&[close], &[], sep, f)
@@ -1051,8 +1051,8 @@ impl<'a> Parser<'a> {
     /// closing bracket.
     fn parse_seq_to_end<T>(
         &mut self,
-        close: ExpTokenPair<'_>,
-        sep: SeqSep<'_>,
+        close: ExpTokenPair,
+        sep: SeqSep,
         f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
     ) -> PResult<'a, (ThinVec<T>, Trailing)> {
         let (val, trailing, recovered) = self.parse_seq_to_before_end(close, sep, f)?;
@@ -1070,9 +1070,9 @@ impl<'a> Parser<'a> {
     /// closing bracket.
     fn parse_unspanned_seq<T>(
         &mut self,
-        open: ExpTokenPair<'_>,
-        close: ExpTokenPair<'_>,
-        sep: SeqSep<'_>,
+        open: ExpTokenPair,
+        close: ExpTokenPair,
+        sep: SeqSep,
         f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
     ) -> PResult<'a, (ThinVec<T>, Trailing)> {
         self.expect(open)?;
@@ -1084,8 +1084,8 @@ impl<'a> Parser<'a> {
     /// closing bracket.
     fn parse_delim_comma_seq<T>(
         &mut self,
-        open: ExpTokenPair<'_>,
-        close: ExpTokenPair<'_>,
+        open: ExpTokenPair,
+        close: ExpTokenPair,
         f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
     ) -> PResult<'a, (ThinVec<T>, Trailing)> {
         self.parse_unspanned_seq(open, close, SeqSep::trailing_allowed(exp!(Comma)), f)
@@ -1094,7 +1094,7 @@ impl<'a> Parser<'a> {
     /// Parses a comma-separated sequence delimited by parentheses (e.g. `(x, y)`).
     /// The function `f` must consume tokens until reaching the next separator or
     /// closing bracket.
-    fn parse_paren_comma_seq<T>(
+    pub fn parse_paren_comma_seq<T>(
         &mut self,
         f: impl FnMut(&mut Parser<'a>) -> PResult<'a, T>,
     ) -> PResult<'a, (ThinVec<T>, Trailing)> {
@@ -1355,7 +1355,8 @@ impl<'a> Parser<'a> {
             AttrArgs::Delimited(args)
         } else if self.eat(exp!(Eq)) {
             let eq_span = self.prev_token.span;
-            AttrArgs::Eq { eq_span, expr: self.parse_expr_force_collect()? }
+            let expr = self.parse_expr_force_collect()?;
+            AttrArgs::Eq { eq_span, expr }
         } else {
             AttrArgs::Empty
         })
@@ -1388,15 +1389,26 @@ impl<'a> Parser<'a> {
             // matching `CloseDelim` we are *after* the delimited sequence,
             // i.e. at depth `d - 1`.
             let target_depth = self.token_cursor.stack.len() - 1;
-            loop {
-                // Advance one token at a time, so `TokenCursor::next()`
-                // can capture these tokens if necessary.
+
+            if let Capturing::No = self.capture_state.capturing {
+                // We are not capturing tokens, so skip to the end of the
+                // delimited sequence. This is a perf win when dealing with
+                // declarative macros that pass large `tt` fragments through
+                // multiple rules, as seen in the uom-0.37.0 crate.
+                self.token_cursor.curr.bump_to_end();
                 self.bump();
-                if self.token_cursor.stack.len() == target_depth {
-                    debug_assert!(self.token.kind.close_delim().is_some());
-                    break;
+                debug_assert_eq!(self.token_cursor.stack.len(), target_depth);
+            } else {
+                loop {
+                    // Advance one token at a time, so `TokenCursor::next()`
+                    // can capture these tokens if necessary.
+                    self.bump();
+                    if self.token_cursor.stack.len() == target_depth {
+                        break;
+                    }
                 }
             }
+            debug_assert!(self.token.kind.close_delim().is_some());
 
             // Consume close delimiter
             self.bump();
diff --git a/compiler/rustc_parse/src/parser/pat.rs b/compiler/rustc_parse/src/parser/pat.rs
index a415849b915..9754691a0b9 100644
--- a/compiler/rustc_parse/src/parser/pat.rs
+++ b/compiler/rustc_parse/src/parser/pat.rs
@@ -24,10 +24,10 @@ use crate::errors::{
     GenericArgsInPatRequireTurbofishSyntax, InclusiveRangeExtraEquals, InclusiveRangeMatchArrow,
     InclusiveRangeNoEnd, InvalidMutInPattern, ParenRangeSuggestion, PatternOnWrongSideOfAt,
     RemoveLet, RepeatedMutInPattern, SwitchRefBoxOrder, TopLevelOrPatternNotAllowed,
-    TopLevelOrPatternNotAllowedSugg, TrailingVertNotAllowed, UnexpectedExpressionInPattern,
-    UnexpectedExpressionInPatternSugg, UnexpectedLifetimeInPattern, UnexpectedParenInRangePat,
-    UnexpectedParenInRangePatSugg, UnexpectedVertVertBeforeFunctionParam,
-    UnexpectedVertVertInPattern, WrapInParens,
+    TopLevelOrPatternNotAllowedSugg, TrailingVertNotAllowed, TrailingVertSuggestion,
+    UnexpectedExpressionInPattern, UnexpectedExpressionInPatternSugg, UnexpectedLifetimeInPattern,
+    UnexpectedParenInRangePat, UnexpectedParenInRangePatSugg,
+    UnexpectedVertVertBeforeFunctionParam, UnexpectedVertVertInPattern, WrapInParens,
 };
 use crate::parser::expr::{DestructuredFloat, could_be_unclosed_char_literal};
 use crate::{exp, maybe_recover_from_interpolated_ty_qpath};
@@ -267,10 +267,9 @@ impl<'a> Parser<'a> {
 
         if let PatKind::Or(pats) = &pat.kind {
             let span = pat.span;
-            let sub = if pats.len() == 1 {
-                Some(TopLevelOrPatternNotAllowedSugg::RemoveLeadingVert {
-                    span: span.with_hi(span.lo() + BytePos(1)),
-                })
+            let sub = if let [_] = &pats[..] {
+                let span = span.with_hi(span.lo() + BytePos(1));
+                Some(TopLevelOrPatternNotAllowedSugg::RemoveLeadingVert { span })
             } else {
                 Some(TopLevelOrPatternNotAllowedSugg::WrapInParens {
                     span,
@@ -362,6 +361,9 @@ impl<'a> Parser<'a> {
                 self.dcx().emit_err(TrailingVertNotAllowed {
                     span: self.token.span,
                     start: lo,
+                    suggestion: TrailingVertSuggestion {
+                        span: self.prev_token.span.shrink_to_hi().with_hi(self.token.span.hi()),
+                    },
                     token: self.token,
                     note_double_vert: self.token.kind == token::OrOr,
                 });
diff --git a/compiler/rustc_parse/src/parser/path.rs b/compiler/rustc_parse/src/parser/path.rs
index a6ec3ea4245..86045648859 100644
--- a/compiler/rustc_parse/src/parser/path.rs
+++ b/compiler/rustc_parse/src/parser/path.rs
@@ -20,11 +20,13 @@ use crate::errors::{
     PathFoundAttributeInParams, PathFoundCVariadicParams, PathSingleColon, PathTripleColon,
 };
 use crate::exp;
-use crate::parser::{CommaRecoveryMode, ExprKind, RecoverColon, RecoverComma};
+use crate::parser::{
+    CommaRecoveryMode, ExprKind, FnContext, FnParseMode, RecoverColon, RecoverComma,
+};
 
 /// Specifies how to parse a path.
 #[derive(Copy, Clone, PartialEq)]
-pub(super) enum PathStyle {
+pub enum PathStyle {
     /// In some contexts, notably in expressions, paths with generic arguments are ambiguous
     /// with something else. For example, in expressions `segment < ....` can be interpreted
     /// as a comparison and `segment ( ....` can be interpreted as a function call.
@@ -148,7 +150,7 @@ impl<'a> Parser<'a> {
         true
     }
 
-    pub(super) fn parse_path(&mut self, style: PathStyle) -> PResult<'a, Path> {
+    pub fn parse_path(&mut self, style: PathStyle) -> PResult<'a, Path> {
         self.parse_path_inner(style, None)
     }
 
@@ -399,7 +401,13 @@ impl<'a> Parser<'a> {
 
                     let dcx = self.dcx();
                     let parse_params_result = self.parse_paren_comma_seq(|p| {
-                        let param = p.parse_param_general(|_| false, false, false);
+                        // Inside parenthesized type arguments, we want types only, not names.
+                        let mode = FnParseMode {
+                            context: FnContext::Free,
+                            req_name: |_| false,
+                            req_body: false,
+                        };
+                        let param = p.parse_param_general(&mode, false, false);
                         param.map(move |param| {
                             if !matches!(param.pat.kind, PatKind::Missing) {
                                 dcx.emit_err(FnPathFoundNamedParams {
diff --git a/compiler/rustc_parse/src/parser/stmt.rs b/compiler/rustc_parse/src/parser/stmt.rs
index 7aacb674253..b4943ff7de6 100644
--- a/compiler/rustc_parse/src/parser/stmt.rs
+++ b/compiler/rustc_parse/src/parser/stmt.rs
@@ -19,8 +19,8 @@ use super::diagnostics::AttemptLocalParseRecovery;
 use super::pat::{PatternLocation, RecoverComma};
 use super::path::PathStyle;
 use super::{
-    AttrWrapper, BlockMode, FnParseMode, ForceCollect, Parser, Restrictions, SemiColonMode,
-    Trailing, UsePreAttrPos,
+    AttrWrapper, BlockMode, FnContext, FnParseMode, ForceCollect, Parser, Restrictions,
+    SemiColonMode, Trailing, UsePreAttrPos,
 };
 use crate::errors::{self, MalformedLoopLabel};
 use crate::exp;
@@ -153,7 +153,7 @@ impl<'a> Parser<'a> {
             attrs.clone(), // FIXME: unwanted clone of attrs
             false,
             true,
-            FnParseMode { req_name: |_| true, req_body: true },
+            FnParseMode { req_name: |_| true, context: FnContext::Free, req_body: true },
             force_collect,
         )? {
             self.mk_stmt(lo.to(item.span), StmtKind::Item(Box::new(item)))
diff --git a/compiler/rustc_parse/src/parser/token_type.rs b/compiler/rustc_parse/src/parser/token_type.rs
index b91548196a3..bd4bb368df0 100644
--- a/compiler/rustc_parse/src/parser/token_type.rs
+++ b/compiler/rustc_parse/src/parser/token_type.rs
@@ -416,8 +416,8 @@ impl TokenType {
 /// is always by used those methods. The second field is only used when the
 /// first field doesn't match.
 #[derive(Clone, Copy, Debug)]
-pub struct ExpTokenPair<'a> {
-    pub tok: &'a TokenKind,
+pub struct ExpTokenPair {
+    pub tok: TokenKind,
     pub token_type: TokenType,
 }
 
@@ -444,7 +444,7 @@ macro_rules! exp {
     // `ExpTokenPair` helper rules.
     (@tok, $tok:ident) => {
         $crate::parser::token_type::ExpTokenPair {
-            tok: &rustc_ast::token::$tok,
+            tok: rustc_ast::token::$tok,
             token_type: $crate::parser::token_type::TokenType::$tok
         }
     };
diff --git a/compiler/rustc_parse/src/parser/ty.rs b/compiler/rustc_parse/src/parser/ty.rs
index 0d479731e73..6168647183f 100644
--- a/compiler/rustc_parse/src/parser/ty.rs
+++ b/compiler/rustc_parse/src/parser/ty.rs
@@ -19,6 +19,7 @@ use crate::errors::{
     NestedCVariadicType, ReturnTypesUseThinArrow,
 };
 use crate::parser::item::FrontMatterParsingMode;
+use crate::parser::{FnContext, FnParseMode};
 use crate::{exp, maybe_recover_from_interpolated_ty_qpath};
 
 /// Signals whether parsing a type should allow `+`.
@@ -136,14 +137,37 @@ impl<'a> Parser<'a> {
     /// The difference from `parse_ty` is that this version allows `...`
     /// (`CVarArgs`) at the top level of the type.
     pub(super) fn parse_ty_for_param(&mut self) -> PResult<'a, Box<Ty>> {
-        self.parse_ty_common(
+        let ty = self.parse_ty_common(
             AllowPlus::Yes,
             AllowCVariadic::Yes,
             RecoverQPath::Yes,
             RecoverReturnSign::Yes,
             None,
             RecoverQuestionMark::Yes,
-        )
+        )?;
+
+        // Recover a trailing `= EXPR` if present.
+        if self.may_recover()
+            && self.check_noexpect(&token::Eq)
+            && self.look_ahead(1, |tok| tok.can_begin_expr())
+        {
+            let snapshot = self.create_snapshot_for_diagnostic();
+            self.bump();
+            let eq_span = self.prev_token.span;
+            match self.parse_expr() {
+                Ok(e) => {
+                    self.dcx()
+                        .struct_span_err(eq_span.to(e.span), "parameter defaults are not supported")
+                        .emit();
+                }
+                Err(diag) => {
+                    diag.cancel();
+                    self.restore_snapshot(snapshot);
+                }
+            }
+        }
+
+        Ok(ty)
     }
 
     /// Parses a type in restricted contexts where `+` is not permitted.
@@ -307,11 +331,11 @@ impl<'a> Parser<'a> {
             // Function pointer type or bound list (trait object type) starting with a poly-trait.
             //   `for<'lt> [unsafe] [extern "ABI"] fn (&'lt S) -> T`
             //   `for<'lt> Trait1<'lt> + Trait2 + 'a`
-            let (lifetime_defs, _) = self.parse_late_bound_lifetime_defs()?;
+            let (bound_vars, _) = self.parse_higher_ranked_binder()?;
             if self.check_fn_front_matter(false, Case::Sensitive) {
                 self.parse_ty_fn_ptr(
                     lo,
-                    lifetime_defs,
+                    bound_vars,
                     Some(self.prev_token.span.shrink_to_lo()),
                     recover_return_sign,
                 )?
@@ -325,7 +349,7 @@ impl<'a> Parser<'a> {
                     let path = self.parse_path(PathStyle::Type)?;
                     let parse_plus = allow_plus == AllowPlus::Yes && self.check_plus();
                     let kind = self.parse_remaining_bounds_path(
-                        lifetime_defs,
+                        bound_vars,
                         path,
                         lo,
                         parse_plus,
@@ -358,7 +382,7 @@ impl<'a> Parser<'a> {
                     let path = self.parse_path(PathStyle::Type)?;
                     let parse_plus = allow_plus == AllowPlus::Yes && self.check_plus();
                     self.parse_remaining_bounds_path(
-                        lifetime_defs,
+                        bound_vars,
                         path,
                         lo,
                         parse_plus,
@@ -442,7 +466,7 @@ impl<'a> Parser<'a> {
             let ty = ts.into_iter().next().unwrap();
             let maybe_bounds = allow_plus == AllowPlus::Yes && self.token.is_like_plus();
             match ty.kind {
-                // `(TY_BOUND_NOPAREN) + BOUND + ...`.
+                // `"(" BareTraitBound ")" "+" Bound "+" ...`.
                 TyKind::Path(None, path) if maybe_bounds => self.parse_remaining_bounds_path(
                     ThinVec::new(),
                     path,
@@ -769,7 +793,12 @@ impl<'a> Parser<'a> {
         if self.may_recover() && self.token == TokenKind::Lt {
             self.recover_fn_ptr_with_generics(lo, &mut params, param_insertion_point)?;
         }
-        let decl = self.parse_fn_decl(|_| false, AllowPlus::No, recover_return_sign)?;
+        let mode = crate::parser::item::FnParseMode {
+            req_name: |_| false,
+            context: FnContext::Free,
+            req_body: false,
+        };
+        let decl = self.parse_fn_decl(&mode, AllowPlus::No, recover_return_sign)?;
 
         let decl_span = span_start.to(self.prev_token.span);
         Ok(TyKind::FnPtr(Box::new(FnPtrTy {
@@ -847,10 +876,13 @@ impl<'a> Parser<'a> {
         Ok(TyKind::ImplTrait(ast::DUMMY_NODE_ID, bounds))
     }
 
-    fn parse_precise_capturing_args(
-        &mut self,
-    ) -> PResult<'a, (ThinVec<PreciseCapturingArg>, Span)> {
-        let lo = self.token.span;
+    /// Parse a use-bound aka precise capturing list.
+    ///
+    /// ```ebnf
+    /// UseBound = "use" "<" (PreciseCapture ("," PreciseCapture)* ","?)? ">"
+    /// PreciseCapture = "Self" | Ident | Lifetime
+    /// ```
+    fn parse_use_bound(&mut self, lo: Span, parens: ast::Parens) -> PResult<'a, GenericBound> {
         self.expect_lt()?;
         let (args, _, _) = self.parse_seq_to_before_tokens(
             &[exp!(Gt)],
@@ -876,7 +908,13 @@ impl<'a> Parser<'a> {
             },
         )?;
         self.expect_gt()?;
-        Ok((args, lo.to(self.prev_token.span)))
+
+        if let ast::Parens::Yes = parens {
+            self.expect(exp!(CloseParen))?;
+            self.report_parenthesized_bound(lo, self.prev_token.span, "precise capturing lists");
+        }
+
+        Ok(GenericBound::Use(args, lo.to(self.prev_token.span)))
     }
 
     /// Is a `dyn B0 + ... + Bn` type allowed here?
@@ -934,9 +972,10 @@ impl<'a> Parser<'a> {
         self.parse_generic_bounds_common(AllowPlus::Yes)
     }
 
-    /// Parses bounds of a type parameter `BOUND + BOUND + ...`, possibly with trailing `+`.
+    /// Parse generic bounds.
     ///
-    /// See `parse_generic_bound` for the `BOUND` grammar.
+    /// Only if `allow_plus` this parses a `+`-separated list of bounds (trailing `+` is admitted).
+    /// Otherwise, this only parses a single bound or none.
     fn parse_generic_bounds_common(&mut self, allow_plus: AllowPlus) -> PResult<'a, GenericBounds> {
         let mut bounds = Vec::new();
 
@@ -982,48 +1021,56 @@ impl<'a> Parser<'a> {
             || self.check_keyword(exp!(Use))
     }
 
-    /// Parses a bound according to the grammar:
+    /// Parse a bound.
+    ///
     /// ```ebnf
-    /// BOUND = TY_BOUND | LT_BOUND
+    /// Bound = LifetimeBound | UseBound | TraitBound
     /// ```
     fn parse_generic_bound(&mut self) -> PResult<'a, GenericBound> {
-        let lo = self.token.span;
         let leading_token = self.prev_token;
+        let lo = self.token.span;
+
+        // We only admit parenthesized *trait* bounds. However, we want to gracefully recover from
+        // other kinds of parenthesized bounds, so parse the opening parenthesis *here*.
+        //
+        // In the future we might want to lift this syntactic restriction and
+        // introduce "`GenericBound::Paren(Box<GenericBound>)`".
         let parens = if self.eat(exp!(OpenParen)) { ast::Parens::Yes } else { ast::Parens::No };
 
-        let bound = if self.token.is_lifetime() {
-            self.parse_generic_lt_bound(lo, parens)?
+        if self.token.is_lifetime() {
+            self.parse_lifetime_bound(lo, parens)
         } else if self.eat_keyword(exp!(Use)) {
-            // parse precise captures, if any. This is `use<'lt, 'lt, P, P>`; a list of
-            // lifetimes and ident params (including SelfUpper). These are validated later
-            // for order, duplication, and whether they actually reference params.
-            let use_span = self.prev_token.span;
-            let (args, args_span) = self.parse_precise_capturing_args()?;
-            GenericBound::Use(args, use_span.to(args_span))
+            self.parse_use_bound(lo, parens)
         } else {
-            self.parse_generic_ty_bound(lo, parens, &leading_token)?
-        };
-
-        Ok(bound)
+            self.parse_trait_bound(lo, parens, &leading_token)
+        }
     }
 
-    /// Parses a lifetime ("outlives") bound, e.g. `'a`, according to:
+    /// Parse a lifetime-bound aka outlives-bound.
+    ///
     /// ```ebnf
-    /// LT_BOUND = LIFETIME
+    /// LifetimeBound = Lifetime
     /// ```
-    fn parse_generic_lt_bound(
-        &mut self,
-        lo: Span,
-        parens: ast::Parens,
-    ) -> PResult<'a, GenericBound> {
+    fn parse_lifetime_bound(&mut self, lo: Span, parens: ast::Parens) -> PResult<'a, GenericBound> {
         let lt = self.expect_lifetime();
-        let bound = GenericBound::Outlives(lt);
+
         if let ast::Parens::Yes = parens {
-            // FIXME(Centril): Consider not erroring here and accepting `('lt)` instead,
-            // possibly introducing `GenericBound::Paren(Box<GenericBound>)`?
-            self.recover_paren_lifetime(lo)?;
+            self.expect(exp!(CloseParen))?;
+            self.report_parenthesized_bound(lo, self.prev_token.span, "lifetime bounds");
         }
-        Ok(bound)
+
+        Ok(GenericBound::Outlives(lt))
+    }
+
+    fn report_parenthesized_bound(&self, lo: Span, hi: Span, kind: &str) -> ErrorGuaranteed {
+        let mut diag =
+            self.dcx().struct_span_err(lo.to(hi), format!("{kind} may not be parenthesized"));
+        diag.multipart_suggestion(
+            "remove the parentheses",
+            vec![(lo, String::new()), (hi, String::new())],
+            Applicability::MachineApplicable,
+        );
+        diag.emit()
     }
 
     /// Emits an error if any trait bound modifiers were present.
@@ -1068,27 +1115,17 @@ impl<'a> Parser<'a> {
         unreachable!("lifetime bound intercepted in `parse_generic_ty_bound` but no modifiers?")
     }
 
-    /// Recover on `('lifetime)` with `(` already eaten.
-    fn recover_paren_lifetime(&mut self, lo: Span) -> PResult<'a, ()> {
-        self.expect(exp!(CloseParen))?;
-        let span = lo.to(self.prev_token.span);
-        let sugg = errors::RemoveParens { lo, hi: self.prev_token.span };
-
-        self.dcx().emit_err(errors::ParenthesizedLifetime { span, sugg });
-        Ok(())
-    }
-
     /// Parses the modifiers that may precede a trait in a bound, e.g. `?Trait` or `[const] Trait`.
     ///
     /// If no modifiers are present, this does not consume any tokens.
     ///
     /// ```ebnf
-    /// CONSTNESS = [["["] "const" ["]"]]
-    /// ASYNCNESS = ["async"]
-    /// POLARITY = ["?" | "!"]
+    /// Constness = ("const" | "[" "const" "]")?
+    /// Asyncness = "async"?
+    /// Polarity = ("?" | "!")?
     /// ```
     ///
-    /// See `parse_generic_ty_bound` for the complete grammar of trait bound modifiers.
+    /// See `parse_trait_bound` for more context.
     fn parse_trait_bound_modifiers(&mut self) -> PResult<'a, TraitBoundModifiers> {
         let modifier_lo = self.token.span;
         let constness = self.parse_bound_constness()?;
@@ -1181,20 +1218,21 @@ impl<'a> Parser<'a> {
         })
     }
 
-    /// Parses a type bound according to:
+    /// Parse a trait bound.
+    ///
     /// ```ebnf
-    /// TY_BOUND = TY_BOUND_NOPAREN | (TY_BOUND_NOPAREN)
-    /// TY_BOUND_NOPAREN = [for<GENERIC_PARAMS> CONSTNESS ASYNCNESS | POLARITY] SIMPLE_PATH
+    /// TraitBound = BareTraitBound | "(" BareTraitBound ")"
+    /// BareTraitBound =
+    ///     (HigherRankedBinder Constness Asyncness | Polarity)
+    ///     TypePath
     /// ```
-    ///
-    /// For example, this grammar accepts `for<'a: 'b> [const] ?m::Trait<'a>`.
-    fn parse_generic_ty_bound(
+    fn parse_trait_bound(
         &mut self,
         lo: Span,
         parens: ast::Parens,
         leading_token: &Token,
     ) -> PResult<'a, GenericBound> {
-        let (mut lifetime_defs, binder_span) = self.parse_late_bound_lifetime_defs()?;
+        let (mut bound_vars, binder_span) = self.parse_higher_ranked_binder()?;
 
         let modifiers_lo = self.token.span;
         let modifiers = self.parse_trait_bound_modifiers()?;
@@ -1217,11 +1255,11 @@ impl<'a> Parser<'a> {
         // e.g. `T: for<'a> 'a` or `T: [const] 'a`.
         if self.token.is_lifetime() {
             let _: ErrorGuaranteed = self.error_lt_bound_with_modifiers(modifiers, binder_span);
-            return self.parse_generic_lt_bound(lo, parens);
+            return self.parse_lifetime_bound(lo, parens);
         }
 
-        if let (more_lifetime_defs, Some(binder_span)) = self.parse_late_bound_lifetime_defs()? {
-            lifetime_defs.extend(more_lifetime_defs);
+        if let (more_bound_vars, Some(binder_span)) = self.parse_higher_ranked_binder()? {
+            bound_vars.extend(more_bound_vars);
             self.dcx().emit_err(errors::BinderBeforeModifiers { binder_span, modifiers_span });
         }
 
@@ -1281,7 +1319,7 @@ impl<'a> Parser<'a> {
         };
 
         if self.may_recover() && self.token == TokenKind::OpenParen {
-            self.recover_fn_trait_with_lifetime_params(&mut path, &mut lifetime_defs)?;
+            self.recover_fn_trait_with_lifetime_params(&mut path, &mut bound_vars)?;
         }
 
         if let ast::Parens::Yes = parens {
@@ -1304,7 +1342,7 @@ impl<'a> Parser<'a> {
         }
 
         let poly_trait =
-            PolyTraitRef::new(lifetime_defs, path, modifiers, lo.to(self.prev_token.span), parens);
+            PolyTraitRef::new(bound_vars, path, modifiers, lo.to(self.prev_token.span), parens);
         Ok(GenericBound::Trait(poly_trait))
     }
 
@@ -1314,7 +1352,8 @@ impl<'a> Parser<'a> {
         self.bump();
         let args_lo = self.token.span;
         let snapshot = self.create_snapshot_for_diagnostic();
-        match self.parse_fn_decl(|_| false, AllowPlus::No, RecoverReturnSign::OnlyFatArrow) {
+        let mode = FnParseMode { req_name: |_| false, context: FnContext::Free, req_body: false };
+        match self.parse_fn_decl(&mode, AllowPlus::No, RecoverReturnSign::OnlyFatArrow) {
             Ok(decl) => {
                 self.dcx().emit_err(ExpectedFnPathFoundFnKeyword { fn_token_span });
                 Some(ast::Path {
@@ -1342,8 +1381,12 @@ impl<'a> Parser<'a> {
         }
     }
 
-    /// Optionally parses `for<$generic_params>`.
-    pub(super) fn parse_late_bound_lifetime_defs(
+    /// Parse an optional higher-ranked binder.
+    ///
+    /// ```ebnf
+    /// HigherRankedBinder = ("for" "<" GenericParams ">")?
+    /// ```
+    pub(super) fn parse_higher_ranked_binder(
         &mut self,
     ) -> PResult<'a, (ThinVec<GenericParam>, Option<Span>)> {
         if self.eat_keyword(exp!(For)) {
@@ -1400,8 +1443,9 @@ impl<'a> Parser<'a> {
 
         // Parse `(T, U) -> R`.
         let inputs_lo = self.token.span;
+        let mode = FnParseMode { req_name: |_| false, context: FnContext::Free, req_body: false };
         let inputs: ThinVec<_> =
-            self.parse_fn_params(|_| false)?.into_iter().map(|input| input.ty).collect();
+            self.parse_fn_params(&mode)?.into_iter().map(|input| input.ty).collect();
         let inputs_span = inputs_lo.to(self.prev_token.span);
         let output = self.parse_ret_ty(AllowPlus::No, RecoverQPath::No, RecoverReturnSign::No)?;
         let args = ast::ParenthesizedArgs {
@@ -1458,8 +1502,7 @@ impl<'a> Parser<'a> {
     pub(super) fn expect_lifetime(&mut self) -> Lifetime {
         if let Some((ident, is_raw)) = self.token.lifetime() {
             if matches!(is_raw, IdentIsRaw::No)
-                && ident.without_first_quote().is_reserved()
-                && ![kw::UnderscoreLifetime, kw::StaticLifetime].contains(&ident.name)
+                && ident.without_first_quote().is_reserved_lifetime()
             {
                 self.dcx().emit_err(errors::KeywordLifetime { span: ident.span });
             }
diff --git a/compiler/rustc_parse_format/Cargo.toml b/compiler/rustc_parse_format/Cargo.toml
index d178fcda1fb..645e34b6e32 100644
--- a/compiler/rustc_parse_format/Cargo.toml
+++ b/compiler/rustc_parse_format/Cargo.toml
@@ -5,7 +5,7 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-rustc-literal-escaper = "0.0.5"
+rustc-literal-escaper.workspace = true
 rustc_lexer = { path = "../rustc_lexer" }
 # tidy-alphabetical-end
 
diff --git a/compiler/rustc_passes/Cargo.toml b/compiler/rustc_passes/Cargo.toml
index ba81ef3103b..c74608a6146 100644
--- a/compiler/rustc_passes/Cargo.toml
+++ b/compiler/rustc_passes/Cargo.toml
@@ -24,5 +24,5 @@ rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 rustc_trait_selection = { path = "../rustc_trait_selection" }
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_passes/messages.ftl b/compiler/rustc_passes/messages.ftl
index b5031f5d02e..498d9a405fa 100644
--- a/compiler/rustc_passes/messages.ftl
+++ b/compiler/rustc_passes/messages.ftl
@@ -13,22 +13,6 @@ passes_abi_ne =
 passes_abi_of =
     fn_abi_of({$fn_name}) = {$fn_abi}
 
-passes_align_attr_application =
-    `#[rustc_align(...)]` should be applied to a function item
-    .label = not a function item
-
-passes_align_on_fields =
-    attribute should be applied to a function or method
-    .warn = {-passes_previously_accepted}
-
-passes_align_should_be_repr_align =
-    `#[rustc_align(...)]` is not supported on {$item} items
-    .suggestion = use `#[repr(align(...))]` instead
-
-passes_allow_incoherent_impl =
-    `rustc_allow_incoherent_impl` attribute should be applied to impl items
-    .label = the only currently supported targets are inherent methods
-
 passes_macro_only_attribute =
     attribute should be applied to a macro
     .label = not a macro
@@ -78,18 +62,10 @@ passes_change_fields_to_be_of_unit_type =
      *[other] fields
     }
 
-passes_cold =
-    {passes_should_be_applied_to_fn}
-    .warn = {-passes_previously_accepted}
-    .label = {passes_should_be_applied_to_fn.label}
-
 passes_collapse_debuginfo =
     `collapse_debuginfo` attribute should be applied to macro definitions
     .label = not a macro definition
 
-passes_confusables = attribute should be applied to an inherent method
-    .label = not an inherent method
-
 passes_const_continue_attr =
     `#[const_continue]` should be applied to a break expression
     .label = not a break expression
@@ -98,15 +74,15 @@ passes_const_stable_not_stable =
     attribute `#[rustc_const_stable]` can only be applied to functions that are declared `#[stable]`
     .label = attribute specified here
 
-passes_coroutine_on_non_closure =
-    attribute should be applied to closures
-    .label = not a closure
+passes_custom_mir_incompatible_dialect_and_phase =
+    The {$dialect} dialect is not compatible with the {$phase} phase
+    .dialect_span = this dialect...
+    .phase_span = ... is not compatible with this phase
+
+passes_custom_mir_phase_requires_dialect =
+    `dialect` key required
+    .phase_span = `phase` argument requires a `dialect` argument
 
-passes_coverage_attribute_not_allowed =
-    coverage attribute not allowed here
-    .not_fn_impl_mod = not a function, impl block, or module
-    .no_body = function has no body
-    .help = coverage attribute can be applied to a function (with body), impl block, or module
 
 passes_dead_codes =
     { $multiple ->
@@ -129,9 +105,6 @@ passes_debug_visualizer_placement =
 passes_debug_visualizer_unreadable =
     couldn't read {$file}: {$error}
 
-passes_deprecated =
-    attribute is ignored here
-
 passes_deprecated_annotation_has_no_effect =
     this `#[deprecated]` annotation has no effect
     .suggestion = remove the unnecessary deprecation attribute
@@ -172,6 +145,10 @@ passes_doc_alias_start_end =
 passes_doc_attr_not_crate_level =
     `#![doc({$attr_name} = "...")]` isn't allowed as a crate-level attribute
 
+passes_doc_attribute_not_attribute =
+    nonexistent builtin attribute `{$attribute}` used in `#[doc(attribute = "...")]`
+    .help = only existing builtin attributes are allowed in core/std
+
 passes_doc_cfg_hide_takes_list =
     `#[doc(cfg_hide(...))]` takes a list of attributes
 
@@ -200,16 +177,16 @@ passes_doc_inline_only_use =
 passes_doc_invalid =
     invalid `doc` attribute
 
-passes_doc_keyword_empty_mod =
-    `#[doc(keyword = "...")]` should be used on empty modules
+passes_doc_keyword_attribute_empty_mod =
+    `#[doc({$attr_name} = "...")]` should be used on empty modules
+
+passes_doc_keyword_attribute_not_mod =
+    `#[doc({$attr_name} = "...")]` should be used on modules
 
 passes_doc_keyword_not_keyword =
     nonexistent keyword `{$keyword}` used in `#[doc(keyword = "...")]`
     .help = only existing keywords are allowed in core/std
 
-passes_doc_keyword_not_mod =
-    `#[doc(keyword = "...")]` should be used on modules
-
 passes_doc_keyword_only_impl =
     `#[doc(keyword = "...")]` should be used on impl blocks
 
@@ -304,10 +281,6 @@ passes_duplicate_lang_item_crate_depends =
 passes_enum_variant_same_name =
     it is impossible to refer to the {$dead_descr} `{$dead_name}` because it is shadowed by this enum variant with the same name
 
-passes_export_name =
-    attribute should be applied to a free function, impl method or static
-    .label = not a free function, impl method or static
-
 passes_extern_main =
     the `main` function cannot be declared in an `extern` block
 
@@ -317,21 +290,10 @@ passes_feature_previously_declared =
 passes_feature_stable_twice =
     feature `{$feature}` is declared stable since {$since}, but was previously declared stable since {$prev_since}
 
-passes_ffi_const_invalid_target =
-    `#[ffi_const]` may only be used on foreign functions
-
-passes_ffi_pure_invalid_target =
-    `#[ffi_pure]` may only be used on foreign functions
-
 passes_has_incoherent_inherent_impl =
     `rustc_has_incoherent_inherent_impls` attribute should be applied to types or traits
     .label = only adts, extern types and traits are supported
 
-passes_ignored_attr =
-    `#[{$sym}]` is ignored on struct fields and match arms
-    .warn = {-passes_previously_accepted}
-    .note = {-passes_see_issue(issue: "80564")}
-
 passes_ignored_attr_with_macro =
     `#[{$sym}]` is ignored on struct fields, match arms and macro defs
     .warn = {-passes_previously_accepted}
@@ -373,22 +335,10 @@ passes_incorrect_target =
 passes_ineffective_unstable_impl = an `#[unstable]` annotation here has no effect
     .note = see issue #55436 <https://github.com/rust-lang/rust/issues/55436> for more information
 
-passes_inline_ignored_constants =
-    `#[inline]` is ignored on constants
-    .warn = {-passes_previously_accepted}
-    .note = {-passes_see_issue(issue: "65833")}
-
 passes_inline_ignored_for_exported =
     `#[inline]` is ignored on externally exported functions
     .help = externally exported functions are functions with `#[no_mangle]`, `#[export_name]`, or `#[linkage]`
 
-passes_inline_ignored_function_prototype =
-    `#[inline]` is ignored on function prototypes
-
-passes_inline_not_fn_or_closure =
-    attribute should be applied to function or closure
-    .label = not a function or closure
-
 passes_inner_crate_level_attr =
     crate-level attribute should be in the root module
 
@@ -438,25 +388,6 @@ passes_link =
     .warn = {-passes_previously_accepted}
     .label = not an `extern` block
 
-passes_link_name =
-    attribute should be applied to a foreign function or static
-    .warn = {-passes_previously_accepted}
-    .label = not a foreign function or static
-    .help = try `#[link(name = "{$value}")]` instead
-
-passes_link_ordinal =
-    attribute should be applied to a foreign function or static
-    .label = not a foreign function or static
-
-passes_link_section =
-    attribute should be applied to a function or static
-    .warn = {-passes_previously_accepted}
-    .label = not a function or static
-
-passes_linkage =
-    attribute should be applied to a function or static
-    .label = not a function definition or static
-
 passes_loop_match_attr =
     `#[loop_match]` should be applied to a loop
     .label = not a loop
@@ -468,9 +399,6 @@ passes_macro_export_on_decl_macro =
     `#[macro_export]` has no effect on declarative macro definitions
     .note = declarative macros follow the same exporting rules as regular items
 
-passes_macro_use =
-    `#[{$name}]` only has an effect on `extern crate` and modules
-
 passes_may_dangle =
     `#[may_dangle]` must be applied to a lifetime or type generic parameter in `Drop` impl
 
@@ -508,9 +436,6 @@ passes_must_not_suspend =
     `must_not_suspend` attribute should be applied to a struct, enum, union, or trait
     .label = is not a struct, enum, union, or trait
 
-passes_must_use_no_effect =
-    `#[must_use]` has no effect when applied to {$article} {$target}
-
 passes_no_link =
     attribute should be applied to an `extern crate` item
     .label = not an `extern crate` item
@@ -529,22 +454,6 @@ passes_no_main_function =
     .teach_note = If you don't know the basics of Rust, you can go look to the Rust Book to get started: https://doc.rust-lang.org/book/
     .non_function_main = non-function item at `crate::main` is found
 
-passes_no_mangle =
-    attribute should be applied to a free function, impl method or static
-    .warn = {-passes_previously_accepted}
-    .label = not a free function, impl method or static
-
-passes_no_mangle_foreign =
-    `#[no_mangle]` has no effect on a foreign {$foreign_item_kind}
-    .warn = {-passes_previously_accepted}
-    .label = foreign {$foreign_item_kind}
-    .note = symbol names in extern blocks are not mangled
-    .suggestion = remove this attribute
-
-passes_no_sanitize =
-    `#[no_sanitize({$attr_str})]` should be applied to {$accepted_kind}
-    .label = not {$accepted_kind}
-
 passes_non_exhaustive_with_default_field_values =
     `#[non_exhaustive]` can't be used to annotate items with default field values
     .label = this struct has default field values
@@ -556,22 +465,11 @@ passes_non_exported_macro_invalid_attrs =
 passes_object_lifetime_err =
     {$repr}
 
-passes_only_has_effect_on =
-    `#[{$attr_name}]` only has an effect on {$target_name ->
-        [function] functions
-        [module] modules
-        [trait_implementation_block] trait implementation blocks
-        [inherent_implementation_block] inherent implementation blocks
-        *[unspecified] (unspecified--this is a compiler bug)
-    }
-
-passes_optimize_invalid_target =
-    attribute applied to an invalid target
-    .label = invalid target
-
 passes_outer_crate_level_attr =
-    crate-level attribute should be an inner attribute: add an exclamation mark: `#![foo]`
+    crate-level attribute should be an inner attribute
 
+passes_outer_crate_level_attr_suggestion =
+    add a `!`
 
 passes_panic_unwind_without_std =
     unwinding panics are not supported without std
@@ -584,10 +482,6 @@ passes_parent_info =
      *[other] {$descr}s
     } in this {$parent_descr}
 
-passes_pass_by_value =
-    `pass_by_value` attribute should be applied to a struct, enum or type alias
-    .label = is not a struct, enum or type alias
-
 passes_proc_macro_bad_sig = {$kind} has incorrect signature
 
 passes_remove_fields =
@@ -604,7 +498,7 @@ passes_repr_align_greater_than_target_max =
     .note = `isize::MAX` is {$size} for the current target
 
 passes_repr_align_should_be_align =
-    `#[repr(align(...))]` is not supported on {$item} items
+    `#[repr(align(...))]` is not supported on {$item}
     .help = use `#[rustc_align(...)]` instead
 
 passes_repr_conflicting =
@@ -619,18 +513,10 @@ passes_rustc_const_stable_indirect_pairing =
 passes_rustc_dirty_clean =
     attribute requires -Z query-dep-graph to be enabled
 
-passes_rustc_force_inline =
-    attribute should be applied to a function
-    .label = not a function definition
-
 passes_rustc_force_inline_coro =
     attribute cannot be applied to a `async`, `gen` or `async gen` function
     .label = `async`, `gen` or `async gen` function
 
-passes_rustc_layout_scalar_valid_range_not_struct =
-    attribute should be applied to a struct
-    .label = not a struct
-
 passes_rustc_legacy_const_generics_index =
     #[rustc_legacy_const_generics] must have one index for each generic parameter
     .label = generic parameters
@@ -664,13 +550,11 @@ passes_rustc_pub_transparent =
     attribute should be applied to `#[repr(transparent)]` types
     .label = not a `#[repr(transparent)]` type
 
-passes_rustc_std_internal_symbol =
-    attribute should be applied to functions or statics
-    .label = not a function or static
-
-passes_rustc_unstable_feature_bound =
-    attribute should be applied to `impl`, trait or free function
-    .label = not an `impl`, trait or free function
+passes_sanitize_attribute_not_allowed =
+    sanitize attribute not allowed here
+    .not_fn_impl_mod = not a function, impl block, or module
+    .no_body = function has no body
+    .help = sanitize attribute can be applied to a function (with body), impl block, or module
 
 passes_should_be_applied_to_fn =
     attribute should be applied to a function definition
@@ -683,24 +567,12 @@ passes_should_be_applied_to_static =
     attribute should be applied to a static
     .label = not a static
 
-passes_should_be_applied_to_struct_enum =
-    attribute should be applied to a struct or enum
-    .label = not a struct or enum
-
 passes_should_be_applied_to_trait =
     attribute should be applied to a trait
     .label = not a trait
 
-passes_stability_promotable =
-    attribute cannot be applied to an expression
-
 passes_string_interpolation_only_works = string interpolation only works in `format!` invocations
 
-passes_target_feature_on_statement =
-    {passes_should_be_applied_to_fn}
-    .warn = {-passes_previously_accepted}
-    .label = {passes_should_be_applied_to_fn.label}
-
 passes_trait_impl_const_stability_mismatch = const stability on the impl does not match the const stability on the trait
 passes_trait_impl_const_stability_mismatch_impl_stable = this impl is (implicitly) stable...
 passes_trait_impl_const_stability_mismatch_impl_unstable = this impl is unstable...
@@ -825,11 +697,6 @@ passes_unused_variable_try_prefix = unused variable: `{$name}`
     .label = unused variable
     .suggestion = if this is intentional, prefix it with an underscore
 
-
-passes_used_static =
-    attribute must be applied to a `static` variable
-    .label = but this is a {$target}
-
 passes_useless_assignment =
     useless assignment of {$is_field_assign ->
         [true] field
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index 93b94a8ba14..2cd4830b5d9 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -10,7 +10,7 @@ use std::collections::hash_map::Entry;
 use std::slice;
 
 use rustc_abi::{Align, ExternAbi, Size};
-use rustc_ast::{AttrStyle, LitKind, MetaItemInner, MetaItemKind, ast, join_path_syms};
+use rustc_ast::{AttrStyle, LitKind, MetaItemInner, MetaItemKind, ast};
 use rustc_attr_parsing::{AttributeParser, Late};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::{Applicability, DiagCtxtHandle, IntoDiagArg, MultiSpan, StashKey};
@@ -18,7 +18,7 @@ use rustc_feature::{
     ACCEPTED_LANG_FEATURES, AttributeDuplicates, AttributeType, BUILTIN_ATTRIBUTE_MAP,
     BuiltinAttribute,
 };
-use rustc_hir::attrs::{AttributeKind, InlineAttr, ReprAttr};
+use rustc_hir::attrs::{AttributeKind, InlineAttr, MirDialect, MirPhase, ReprAttr, SanitizerSet};
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::LocalModDefId;
 use rustc_hir::intravisit::{self, Visitor};
@@ -40,7 +40,6 @@ use rustc_session::lint;
 use rustc_session::lint::builtin::{
     CONFLICTING_REPR_HINTS, INVALID_DOC_ATTRIBUTES, INVALID_MACRO_EXPORT_ARGUMENTS,
     MALFORMED_DIAGNOSTIC_ATTRIBUTES, MISPLACED_DIAGNOSTIC_ATTRIBUTES, UNUSED_ATTRIBUTES,
-    USELESS_DEPRECATED,
 };
 use rustc_session::parse::feature_err;
 use rustc_span::edition::Edition;
@@ -50,7 +49,6 @@ use rustc_trait_selection::infer::{TyCtxtInferExt, ValuePairs};
 use rustc_trait_selection::traits::ObligationCtxt;
 use tracing::debug;
 
-use crate::errors::AlignOnFields;
 use crate::{errors, fluent_generated as fluent};
 
 #[derive(LintDiagnostic)]
@@ -101,6 +99,21 @@ impl IntoDiagArg for ProcMacroKind {
     }
 }
 
+#[derive(Clone, Copy)]
+enum DocFakeItemKind {
+    Attribute,
+    Keyword,
+}
+
+impl DocFakeItemKind {
+    fn name(self) -> &'static str {
+        match self {
+            Self::Attribute => "attribute",
+            Self::Keyword => "keyword",
+        }
+    }
+}
+
 struct CheckAttrVisitor<'tcx> {
     tcx: TyCtxt<'tcx>,
 
@@ -134,56 +147,12 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 Attribute::Parsed(AttributeKind::ProcMacroAttribute(_)) => {
                     self.check_proc_macro(hir_id, target, ProcMacroKind::Attribute);
                 }
-                Attribute::Parsed(AttributeKind::ProcMacroDerive { span: attr_span, .. }) => {
-                    self.check_generic_attr(
-                        hir_id,
-                        sym::proc_macro_derive,
-                        *attr_span,
-                        target,
-                        Target::Fn,
-                    );
+                Attribute::Parsed(AttributeKind::ProcMacroDerive { .. }) => {
                     self.check_proc_macro(hir_id, target, ProcMacroKind::Derive)
                 }
-                Attribute::Parsed(
-                    AttributeKind::SkipDuringMethodDispatch { span: attr_span, .. }
-                    | AttributeKind::Coinductive(attr_span)
-                    | AttributeKind::ConstTrait(attr_span)
-                    | AttributeKind::DenyExplicitImpl(attr_span)
-                    | AttributeKind::DoNotImplementViaObject(attr_span),
-                ) => {
-                    self.check_must_be_applied_to_trait(*attr_span, span, target);
-                }
-                &Attribute::Parsed(
-                    AttributeKind::SpecializationTrait(attr_span)
-                    | AttributeKind::UnsafeSpecializationMarker(attr_span)
-                    | AttributeKind::ParenSugar(attr_span),
-                ) => {
-                    // FIXME: more validation is needed
-                    self.check_must_be_applied_to_trait(attr_span, span, target);
-                }
                 &Attribute::Parsed(AttributeKind::TypeConst(attr_span)) => {
                     self.check_type_const(hir_id, attr_span, target)
                 }
-                &Attribute::Parsed(AttributeKind::Marker(attr_span)) => {
-                    self.check_marker(hir_id, attr_span, span, target)
-                }
-                Attribute::Parsed(AttributeKind::Fundamental | AttributeKind::CoherenceIsCore) => {
-                    // FIXME: add validation
-                }
-                &Attribute::Parsed(AttributeKind::AllowIncoherentImpl(attr_span)) => {
-                    self.check_allow_incoherent_impl(attr_span, span, target)
-                }
-                Attribute::Parsed(AttributeKind::Confusables { first_span, .. }) => {
-                    self.check_confusables(*first_span, target);
-                }
-                Attribute::Parsed(AttributeKind::AutomaticallyDerived(attr_span)) => self
-                    .check_generic_attr(
-                        hir_id,
-                        sym::automatically_derived,
-                        *attr_span,
-                        target,
-                        Target::Impl { of_trait: true },
-                    ),
                 Attribute::Parsed(
                     AttributeKind::Stability {
                         span: attr_span,
@@ -193,13 +162,10 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                         span: attr_span,
                         stability: PartialConstStability { level, feature, .. },
                     },
-                ) => self.check_stability(*attr_span, span, level, *feature, target),
+                ) => self.check_stability(*attr_span, span, level, *feature),
                 Attribute::Parsed(AttributeKind::Inline(InlineAttr::Force { .. }, ..)) => {} // handled separately below
                 Attribute::Parsed(AttributeKind::Inline(kind, attr_span)) => {
-                    self.check_inline(hir_id, *attr_span, span, kind, target)
-                }
-                Attribute::Parsed(AttributeKind::Optimize(_, attr_span)) => {
-                    self.check_optimize(hir_id, *attr_span, span, target)
+                    self.check_inline(hir_id, *attr_span, kind, target)
                 }
                 Attribute::Parsed(AttributeKind::LoopMatch(attr_span)) => {
                     self.check_loop_match(hir_id, *attr_span, target)
@@ -207,11 +173,8 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 Attribute::Parsed(AttributeKind::ConstContinue(attr_span)) => {
                     self.check_const_continue(hir_id, *attr_span, target)
                 }
-                Attribute::Parsed(AttributeKind::AllowInternalUnsafe(attr_span)) => {
-                    self.check_allow_internal_unsafe(hir_id, *attr_span, span, target, attrs)
-                }
-                Attribute::Parsed(AttributeKind::AllowInternalUnstable(_, first_span)) => {
-                    self.check_allow_internal_unstable(hir_id, *first_span, span, target, attrs)
+                Attribute::Parsed(AttributeKind::AllowInternalUnsafe(attr_span) | AttributeKind::AllowInternalUnstable(.., attr_span)) => {
+                    self.check_macro_only_attr(*attr_span, span, target, attrs)
                 }
                 Attribute::Parsed(AttributeKind::AllowConstFnUnstable(_, first_span)) => {
                     self.check_rustc_allow_const_fn_unstable(hir_id, *first_span, span, target)
@@ -219,12 +182,8 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 Attribute::Parsed(AttributeKind::Deprecation { .. }) => {
                     self.check_deprecated(hir_id, attr, span, target)
                 }
-                Attribute::Parsed(AttributeKind::TargetFeature(_, attr_span)) => {
-                    self.check_target_feature(hir_id, *attr_span, span, target, attrs)
-                }
-                Attribute::Parsed(AttributeKind::DocComment { .. }) => { /* `#[doc]` is actually a lot more than just doc comments, so is checked below*/
-                }
-                Attribute::Parsed(AttributeKind::Repr { .. }) => { /* handled below this loop and elsewhere */
+                Attribute::Parsed(AttributeKind::TargetFeature{ attr_span, ..}) => {
+                    self.check_target_feature(hir_id, *attr_span, target, attrs)
                 }
                 Attribute::Parsed(AttributeKind::RustcObjectLifetimeDefault) => {
                     self.check_object_lifetime_default(hir_id);
@@ -232,59 +191,32 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 &Attribute::Parsed(AttributeKind::PubTransparent(attr_span)) => {
                     self.check_rustc_pub_transparent(attr_span, span, attrs)
                 }
-                Attribute::Parsed(AttributeKind::Cold(attr_span)) => {
-                    self.check_cold(hir_id, *attr_span, span, target)
-                }
-                Attribute::Parsed(AttributeKind::ExportName { span: attr_span, .. }) => {
-                    self.check_export_name(hir_id, *attr_span, span, target)
-                }
                 Attribute::Parsed(AttributeKind::Align { align, span: attr_span }) => {
-                    self.check_align(span, hir_id, target, *align, *attr_span)
-                }
-                Attribute::Parsed(AttributeKind::LinkSection { span: attr_span, .. }) => {
-                    self.check_link_section(hir_id, *attr_span, span, target)
-                }
-                Attribute::Parsed(AttributeKind::MacroUse { span, .. }) => {
-                    self.check_macro_use(hir_id, sym::macro_use, *span, target)
+                    self.check_align(*align, *attr_span)
                 }
-                Attribute::Parsed(AttributeKind::MacroEscape(span)) => {
-                    self.check_macro_use(hir_id, sym::macro_escape, *span, target)
-                }
-                Attribute::Parsed(AttributeKind::Naked(attr_span)) => {
-                    self.check_naked(hir_id, *attr_span, span, target)
-                }
-                Attribute::Parsed(AttributeKind::NoImplicitPrelude(attr_span)) => self
-                    .check_generic_attr(
-                        hir_id,
-                        sym::no_implicit_prelude,
-                        *attr_span,
-                        target,
-                        Target::Mod,
-                    ),
-                Attribute::Parsed(AttributeKind::Path(_, attr_span)) => {
-                    self.check_generic_attr(hir_id, sym::path, *attr_span, target, Target::Mod)
+                Attribute::Parsed(AttributeKind::Naked(..)) => {
+                    self.check_naked(hir_id, target)
                 }
                 Attribute::Parsed(AttributeKind::TrackCaller(attr_span)) => {
-                    self.check_track_caller(hir_id, *attr_span, attrs, span, target)
+                    self.check_track_caller(hir_id, *attr_span, attrs, target)
                 }
                 Attribute::Parsed(AttributeKind::NonExhaustive(attr_span)) => {
-                    self.check_non_exhaustive(hir_id, *attr_span, span, target, item)
+                    self.check_non_exhaustive(*attr_span, span, target, item)
                 }
-                Attribute::Parsed(
-                    AttributeKind::RustcLayoutScalarValidRangeStart(_num, attr_span)
-                    | AttributeKind::RustcLayoutScalarValidRangeEnd(_num, attr_span),
-                ) => self.check_rustc_layout_scalar_valid_range(*attr_span, span, target),
-                Attribute::Parsed(AttributeKind::ExportStable) => {
-                    // handled in `check_export`
+                &Attribute::Parsed(AttributeKind::FfiPure(attr_span)) => {
+                    self.check_ffi_pure(attr_span, attrs)
                 }
-                &Attribute::Parsed(AttributeKind::FfiConst(attr_span)) => {
-                    self.check_ffi_const(attr_span, target)
+                Attribute::Parsed(AttributeKind::MayDangle(attr_span)) => {
+                    self.check_may_dangle(hir_id, *attr_span)
                 }
-                &Attribute::Parsed(AttributeKind::FfiPure(attr_span)) => {
-                    self.check_ffi_pure(attr_span, attrs, target)
+                &Attribute::Parsed(AttributeKind::CustomMir(dialect, phase, attr_span)) => {
+                    self.check_custom_mir(dialect, phase, attr_span)
                 }
-                Attribute::Parsed(AttributeKind::UnstableFeatureBound(syms)) => {
-                    self.check_unstable_feature_bound(syms.first().unwrap().1, span, target)
+                &Attribute::Parsed(AttributeKind::Sanitize { on_set, off_set, span: attr_span}) => {
+                    self.check_sanitize(attr_span, on_set | off_set, span, target);
+                },
+                Attribute::Parsed(AttributeKind::Link(_, attr_span)) => {
+                    self.check_link(hir_id, *attr_span, span, target)
                 }
                 Attribute::Parsed(
                     AttributeKind::BodyStability { .. }
@@ -292,46 +224,53 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                     | AttributeKind::MacroTransparency(_)
                     | AttributeKind::Pointee(..)
                     | AttributeKind::Dummy
-                    | AttributeKind::RustcBuiltinMacro { .. },
+                    | AttributeKind::RustcBuiltinMacro { .. }
+                    | AttributeKind::Ignore { .. }
+                    | AttributeKind::Path(..)
+                    | AttributeKind::NoImplicitPrelude(..)
+                    | AttributeKind::AutomaticallyDerived(..)
+                    | AttributeKind::Marker(..)
+                    | AttributeKind::SkipDuringMethodDispatch { .. }
+                    | AttributeKind::Coinductive(..)
+                    | AttributeKind::ConstTrait(..)
+                    | AttributeKind::DenyExplicitImpl(..)
+                    | AttributeKind::DoNotImplementViaObject(..)
+                    | AttributeKind::SpecializationTrait(..)
+                    | AttributeKind::UnsafeSpecializationMarker(..)
+                    | AttributeKind::ParenSugar(..)
+                    | AttributeKind::AllowIncoherentImpl(..)
+                    | AttributeKind::Confusables { .. }
+                    // `#[doc]` is actually a lot more than just doc comments, so is checked below
+                    | AttributeKind::DocComment {..}
+                    // handled below this loop and elsewhere
+                    | AttributeKind::Repr { .. }
+                    | AttributeKind::Cold(..)
+                    | AttributeKind::ExportName { .. }
+                    | AttributeKind::CoherenceIsCore
+                    | AttributeKind::Fundamental
+                    | AttributeKind::Optimize(..)
+                    | AttributeKind::LinkSection { .. }
+                    | AttributeKind::MacroUse { .. }
+                    | AttributeKind::MacroEscape( .. )
+                    | AttributeKind::RustcLayoutScalarValidRangeStart(..)
+                    | AttributeKind::RustcLayoutScalarValidRangeEnd(..)
+                    | AttributeKind::ExportStable
+                    | AttributeKind::FfiConst(..)
+                    | AttributeKind::UnstableFeatureBound(..)
+                    | AttributeKind::AsPtr(..)
+                    | AttributeKind::LinkName { .. }
+                    | AttributeKind::LinkOrdinal { .. }
+                    | AttributeKind::NoMangle(..)
+                    | AttributeKind::Used { .. }
+                    | AttributeKind::PassByValue (..)
+                    | AttributeKind::StdInternalSymbol (..)
+                    | AttributeKind::Coverage (..)
+                    | AttributeKind::ShouldPanic { .. }
+                    | AttributeKind::Coroutine(..)
+                    | AttributeKind::Linkage(..)
+                    | AttributeKind::MustUse { .. }
+                    | AttributeKind::CrateName { .. }
                 ) => { /* do nothing  */ }
-                Attribute::Parsed(AttributeKind::AsPtr(attr_span)) => {
-                    self.check_applied_to_fn_or_method(hir_id, *attr_span, span, target)
-                }
-                Attribute::Parsed(AttributeKind::LinkName { span: attr_span, name }) => {
-                    self.check_link_name(hir_id, *attr_span, *name, span, target)
-                }
-                Attribute::Parsed(AttributeKind::LinkOrdinal { span: attr_span, .. }) => {
-                    self.check_link_ordinal(*attr_span, span, target)
-                }
-                Attribute::Parsed(AttributeKind::MayDangle(attr_span)) => {
-                    self.check_may_dangle(hir_id, *attr_span)
-                }
-                Attribute::Parsed(AttributeKind::Ignore { span, .. }) => {
-                    self.check_generic_attr(hir_id, sym::ignore, *span, target, Target::Fn)
-                }
-                Attribute::Parsed(AttributeKind::MustUse { span, .. }) => {
-                    self.check_must_use(hir_id, *span, target)
-                }
-                Attribute::Parsed(AttributeKind::NoMangle(attr_span)) => {
-                    self.check_no_mangle(hir_id, *attr_span, span, target)
-                }
-                Attribute::Parsed(AttributeKind::Used { span: attr_span, .. }) => {
-                    self.check_used(*attr_span, target, span);
-                }
-                Attribute::Parsed(AttributeKind::ShouldPanic { span: attr_span, .. }) => self
-                    .check_generic_attr(hir_id, sym::should_panic, *attr_span, target, Target::Fn),
-                &Attribute::Parsed(AttributeKind::PassByValue(attr_span)) => {
-                    self.check_pass_by_value(attr_span, span, target)
-                }
-                &Attribute::Parsed(AttributeKind::StdInternalSymbol(attr_span)) => {
-                    self.check_rustc_std_internal_symbol(attr_span, span, target)
-                }
-                &Attribute::Parsed(AttributeKind::Coverage(attr_span, _)) => {
-                    self.check_coverage(attr_span, span, target)
-                }
-                &Attribute::Parsed(AttributeKind::Coroutine(attr_span)) => {
-                    self.check_coroutine(attr_span, target)
-                }
                 Attribute::Unparsed(attr_item) => {
                     style = Some(attr_item.style);
                     match attr.path().as_slice() {
@@ -341,9 +280,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                         [sym::diagnostic, sym::on_unimplemented, ..] => {
                             self.check_diagnostic_on_unimplemented(attr.span(), hir_id, target)
                         }
-                        [sym::no_sanitize, ..] => {
-                            self.check_no_sanitize(attr, span, target)
-                        }
                         [sym::thread_local, ..] => self.check_thread_local(attr, span, target),
                         [sym::doc, ..] => self.check_doc_attrs(
                             attr,
@@ -387,15 +323,10 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                         [sym::rustc_has_incoherent_inherent_impls, ..] => {
                             self.check_has_incoherent_inherent_impls(attr, span, target)
                         }
-                        [sym::ffi_pure, ..] => self.check_ffi_pure(attr.span(), attrs, target),
-                        [sym::ffi_const, ..] => self.check_ffi_const(attr.span(), target),
-                        [sym::link, ..] => self.check_link(hir_id, attr, span, target),
-                        [sym::path, ..] => self.check_generic_attr_unparsed(hir_id, attr, target, Target::Mod),
                         [sym::macro_export, ..] => self.check_macro_export(hir_id, attr, target),
                         [sym::autodiff_forward, ..] | [sym::autodiff_reverse, ..] => {
                             self.check_autodiff(hir_id, attr, span, target)
                         }
-                        [sym::linkage, ..] => self.check_linkage(attr, span, target),
                         [
                             // ok
                             sym::allow
@@ -418,8 +349,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                             | sym::panic_handler
                             | sym::lang
                             | sym::needs_allocator
-                            | sym::default_lib_allocator
-                            | sym::custom_mir,
+                            | sym::default_lib_allocator,
                             ..
                         ] => {}
                         [name, rest@..] => {
@@ -455,22 +385,46 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
             let builtin = attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name));
 
             if hir_id != CRATE_HIR_ID {
-                if let Some(BuiltinAttribute { type_: AttributeType::CrateLevel, .. }) =
-                    attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name))
-                {
-                    match style {
-                        Some(ast::AttrStyle::Outer) => self.tcx.emit_node_span_lint(
-                            UNUSED_ATTRIBUTES,
-                            hir_id,
-                            attr.span(),
-                            errors::OuterCrateLevelAttr,
-                        ),
-                        Some(ast::AttrStyle::Inner) | None => self.tcx.emit_node_span_lint(
-                            UNUSED_ATTRIBUTES,
-                            hir_id,
-                            attr.span(),
-                            errors::InnerCrateLevelAttr,
-                        ),
+                match attr {
+                    Attribute::Parsed(_) => { /* Already validated. */ }
+                    Attribute::Unparsed(attr) => {
+                        // FIXME(jdonszelmann): remove once all crate-level attrs are parsed and caught by
+                        // the above
+                        if let Some(BuiltinAttribute { type_: AttributeType::CrateLevel, .. }) =
+                            attr.path
+                                .segments
+                                .first()
+                                .and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name))
+                        {
+                            match attr.style {
+                                ast::AttrStyle::Outer => {
+                                    let attr_span = attr.span;
+                                    let bang_position = self
+                                        .tcx
+                                        .sess
+                                        .source_map()
+                                        .span_until_char(attr_span, '[')
+                                        .shrink_to_hi();
+
+                                    self.tcx.emit_node_span_lint(
+                                        UNUSED_ATTRIBUTES,
+                                        hir_id,
+                                        attr.span,
+                                        errors::OuterCrateLevelAttr {
+                                            suggestion: errors::OuterCrateLevelAttrSuggestion {
+                                                bang_position,
+                                            },
+                                        },
+                                    )
+                                }
+                                ast::AttrStyle::Inner => self.tcx.emit_node_span_lint(
+                                    UNUSED_ATTRIBUTES,
+                                    hir_id,
+                                    attr.span,
+                                    errors::InnerCrateLevelAttr,
+                                ),
+                            }
+                        }
                     }
                 }
             }
@@ -483,7 +437,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
 
         self.check_repr(attrs, span, target, item, hir_id);
-        self.check_rustc_force_inline(hir_id, attrs, span, target);
+        self.check_rustc_force_inline(hir_id, attrs, target);
         self.check_mix_no_mangle_export(hir_id, attrs);
     }
 
@@ -496,15 +450,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         );
     }
 
-    fn inline_attr_str_error_without_macro_def(&self, hir_id: HirId, attr_span: Span, sym: &str) {
-        self.tcx.emit_node_span_lint(
-            UNUSED_ATTRIBUTES,
-            hir_id,
-            attr_span,
-            errors::IgnoredAttr { sym },
-        );
-    }
-
     /// Checks if `#[diagnostic::do_not_recommend]` is applied on a trait impl and that it has no
     /// arguments.
     fn check_do_not_recommend(
@@ -552,66 +497,41 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
     }
 
     /// Checks if an `#[inline]` is applied to a function or a closure.
-    fn check_inline(
-        &self,
-        hir_id: HirId,
-        attr_span: Span,
-        defn_span: Span,
-        kind: &InlineAttr,
-        target: Target,
-    ) {
+    fn check_inline(&self, hir_id: HirId, attr_span: Span, kind: &InlineAttr, target: Target) {
         match target {
             Target::Fn
             | Target::Closure
-            | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => {}
-            Target::Method(MethodKind::Trait { body: false }) | Target::ForeignFn => {
-                self.tcx.emit_node_span_lint(
-                    UNUSED_ATTRIBUTES,
-                    hir_id,
-                    attr_span,
-                    errors::IgnoredInlineAttrFnProto,
-                )
-            }
-            // FIXME(#65833): We permit associated consts to have an `#[inline]` attribute with
-            // just a lint, because we previously erroneously allowed it and some crates used it
-            // accidentally, to be compatible with crates depending on them, we can't throw an
-            // error here.
-            Target::AssocConst => self.tcx.emit_node_span_lint(
-                UNUSED_ATTRIBUTES,
-                hir_id,
-                attr_span,
-                errors::IgnoredInlineAttrConstants,
-            ),
-            // FIXME(#80564): Same for fields, arms, and macro defs
-            Target::Field | Target::Arm | Target::MacroDef => {
-                self.inline_attr_str_error_with_macro_def(hir_id, attr_span, "inline")
-            }
-            _ => {
-                self.dcx().emit_err(errors::InlineNotFnOrClosure { attr_span, defn_span });
-            }
-        }
-
-        // `#[inline]` is ignored if the symbol must be codegened upstream because it's exported.
-        if let Some(did) = hir_id.as_owner()
-            && self.tcx.def_kind(did).has_codegen_attrs()
-            && kind != &InlineAttr::Never
-        {
-            let attrs = self.tcx.codegen_fn_attrs(did);
-            // Not checking naked as `#[inline]` is forbidden for naked functions anyways.
-            if attrs.contains_extern_indicator() {
-                self.tcx.emit_node_span_lint(
-                    UNUSED_ATTRIBUTES,
-                    hir_id,
-                    attr_span,
-                    errors::InlineIgnoredForExported {},
-                );
+            | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => {
+                // `#[inline]` is ignored if the symbol must be codegened upstream because it's exported.
+                if let Some(did) = hir_id.as_owner()
+                    && self.tcx.def_kind(did).has_codegen_attrs()
+                    && kind != &InlineAttr::Never
+                {
+                    let attrs = self.tcx.codegen_fn_attrs(did);
+                    // Not checking naked as `#[inline]` is forbidden for naked functions anyways.
+                    if attrs.contains_extern_indicator() {
+                        self.tcx.emit_node_span_lint(
+                            UNUSED_ATTRIBUTES,
+                            hir_id,
+                            attr_span,
+                            errors::InlineIgnoredForExported {},
+                        );
+                    }
+                }
             }
+            _ => {}
         }
     }
 
-    /// Checks that `#[coverage(..)]` is applied to a function/closure/method,
-    /// or to an impl block or module.
-    fn check_coverage(&self, attr_span: Span, target_span: Span, target: Target) {
+    /// Checks that the `#[sanitize(..)]` attribute is applied to a
+    /// function/closure/method, or to an impl block or module.
+    fn check_sanitize(
+        &self,
+        attr_span: Span,
+        set: SanitizerSet,
+        target_span: Span,
+        target: Target,
+    ) {
         let mut not_fn_impl_mod = None;
         let mut no_body = None;
 
@@ -621,6 +541,14 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
             | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent)
             | Target::Impl { .. }
             | Target::Mod => return,
+            Target::Static
+                // if we mask out the address bits, i.e. *only* address was set,
+                // we allow it
+                if set & !(SanitizerSet::ADDRESS | SanitizerSet::KERNELADDRESS)
+                    == SanitizerSet::empty() =>
+            {
+                return;
+            }
 
             // These are "functions", but they aren't allowed because they don't
             // have a body, so the usual explanation would be confusing.
@@ -633,7 +561,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
             }
         }
 
-        self.dcx().emit_err(errors::CoverageAttributeNotAllowed {
+        self.dcx().emit_err(errors::SanitizeAttributeNotAllowed {
             attr_span,
             not_fn_impl_mod,
             no_body,
@@ -641,105 +569,8 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         });
     }
 
-    /// Checks that `#[optimize(..)]` is applied to a function/closure/method,
-    /// or to an impl block or module.
-    fn check_optimize(&self, hir_id: HirId, attr_span: Span, span: Span, target: Target) {
-        let is_valid = matches!(
-            target,
-            Target::Fn
-                | Target::Closure
-                | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent)
-        );
-        if !is_valid {
-            self.dcx().emit_err(errors::OptimizeInvalidTarget {
-                attr_span,
-                defn_span: span,
-                on_crate: hir_id == CRATE_HIR_ID,
-            });
-        }
-    }
-
-    fn check_no_sanitize(&self, attr: &Attribute, span: Span, target: Target) {
-        if let Some(list) = attr.meta_item_list() {
-            for item in list.iter() {
-                let sym = item.name();
-                match sym {
-                    Some(s @ sym::address | s @ sym::hwaddress) => {
-                        let is_valid =
-                            matches!(target, Target::Fn | Target::Method(..) | Target::Static);
-                        if !is_valid {
-                            self.dcx().emit_err(errors::NoSanitize {
-                                attr_span: item.span(),
-                                defn_span: span,
-                                accepted_kind: "a function or static",
-                                attr_str: s.as_str(),
-                            });
-                        }
-                    }
-                    _ => {
-                        let is_valid = matches!(target, Target::Fn | Target::Method(..));
-                        if !is_valid {
-                            self.dcx().emit_err(errors::NoSanitize {
-                                attr_span: item.span(),
-                                defn_span: span,
-                                accepted_kind: "a function",
-                                attr_str: &match sym {
-                                    Some(name) => name.to_string(),
-                                    None => "...".to_string(),
-                                },
-                            });
-                        }
-                    }
-                }
-            }
-        }
-    }
-
-    /// FIXME: Remove when all attributes are ported to the new parser
-    fn check_generic_attr_unparsed(
-        &self,
-        hir_id: HirId,
-        attr: &Attribute,
-        target: Target,
-        allowed_target: Target,
-    ) {
-        if target != allowed_target {
-            let attr_name = join_path_syms(attr.path());
-            self.tcx.emit_node_span_lint(
-                UNUSED_ATTRIBUTES,
-                hir_id,
-                attr.span(),
-                errors::OnlyHasEffectOn {
-                    attr_name,
-                    target_name: allowed_target.name().replace(' ', "_"),
-                },
-            );
-        }
-    }
-
-    fn check_generic_attr(
-        &self,
-        hir_id: HirId,
-        attr_name: Symbol,
-        attr_span: Span,
-        target: Target,
-        allowed_target: Target,
-    ) {
-        if target != allowed_target {
-            self.tcx.emit_node_span_lint(
-                UNUSED_ATTRIBUTES,
-                hir_id,
-                attr_span,
-                errors::OnlyHasEffectOn {
-                    attr_name: attr_name.to_string(),
-                    target_name: allowed_target.name().replace(' ', "_"),
-                },
-            );
-        }
-    }
-
     /// Checks if `#[naked]` is applied to a function definition.
-    fn check_naked(&self, hir_id: HirId, attr_span: Span, span: Span, target: Target) {
+    fn check_naked(&self, hir_id: HirId, target: Target) {
         match target {
             Target::Fn
             | Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => {
@@ -758,13 +589,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                     .emit();
                 }
             }
-            _ => {
-                self.dcx().emit_err(errors::AttrShouldBeAppliedToFn {
-                    attr_span,
-                    defn_span: span,
-                    on_crate: hir_id == CRATE_HIR_ID,
-                });
-            }
+            _ => {}
         }
     }
 
@@ -787,7 +612,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
             }
         }
     }
-
     /// Checks if `#[collapse_debuginfo]` is applied to a macro.
     fn check_collapse_debuginfo(&self, attr: &Attribute, span: Span, target: Target) {
         match target {
@@ -807,7 +631,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         hir_id: HirId,
         attr_span: Span,
         attrs: &[Attribute],
-        span: Span,
         target: Target,
     ) {
         match target {
@@ -827,28 +650,13 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                     });
                 }
             }
-            Target::Method(..) | Target::ForeignFn | Target::Closure => {}
-            // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
-            // `#[track_caller]` attribute with just a lint, because we previously
-            // erroneously allowed it and some crates used it accidentally, to be compatible
-            // with crates depending on them, we can't throw an error here.
-            Target::Field | Target::Arm | Target::MacroDef => {
-                self.inline_attr_str_error_with_macro_def(hir_id, attr_span, "track_caller");
-            }
-            _ => {
-                self.dcx().emit_err(errors::TrackedCallerWrongLocation {
-                    attr_span,
-                    defn_span: span,
-                    on_crate: hir_id == CRATE_HIR_ID,
-                });
-            }
+            _ => {}
         }
     }
 
     /// Checks if the `#[non_exhaustive]` attribute on an `item` is valid.
     fn check_non_exhaustive(
         &self,
-        hir_id: HirId,
         attr_span: Span,
         span: Span,
         target: Target,
@@ -869,36 +677,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                     });
                 }
             }
-            Target::Enum | Target::Variant => {}
-            // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
-            // `#[non_exhaustive]` attribute with just a lint, because we previously
-            // erroneously allowed it and some crates used it accidentally, to be compatible
-            // with crates depending on them, we can't throw an error here.
-            Target::Field | Target::Arm | Target::MacroDef => {
-                self.inline_attr_str_error_with_macro_def(hir_id, attr_span, "non_exhaustive");
-            }
-            _ => {
-                self.dcx()
-                    .emit_err(errors::NonExhaustiveWrongLocation { attr_span, defn_span: span });
-            }
-        }
-    }
-
-    /// Checks if the `#[marker]` attribute on an `item` is valid.
-    fn check_marker(&self, hir_id: HirId, attr_span: Span, span: Span, target: Target) {
-        match target {
-            Target::Trait => {}
-            // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
-            // `#[marker]` attribute with just a lint, because we previously
-            // erroneously allowed it and some crates used it accidentally, to be compatible
-            // with crates depending on them, we can't throw an error here.
-            Target::Field | Target::Arm | Target::MacroDef => {
-                self.inline_attr_str_error_with_macro_def(hir_id, attr_span, "marker");
-            }
-            _ => {
-                self.dcx()
-                    .emit_err(errors::AttrShouldBeAppliedToTrait { attr_span, defn_span: span });
-            }
+            _ => {}
         }
     }
 
@@ -907,7 +686,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         &self,
         hir_id: HirId,
         attr_span: Span,
-        span: Span,
         target: Target,
         attrs: &[Attribute],
     ) {
@@ -930,30 +708,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                     });
                 }
             }
-            // FIXME: #[target_feature] was previously erroneously allowed on statements and some
-            // crates used this, so only emit a warning.
-            Target::Statement => {
-                self.tcx.emit_node_span_lint(
-                    UNUSED_ATTRIBUTES,
-                    hir_id,
-                    attr_span,
-                    errors::TargetFeatureOnStatement,
-                );
-            }
-            // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
-            // `#[target_feature]` attribute with just a lint, because we previously
-            // erroneously allowed it and some crates used it accidentally, to be compatible
-            // with crates depending on them, we can't throw an error here.
-            Target::Field | Target::Arm | Target::MacroDef => {
-                self.inline_attr_str_error_with_macro_def(hir_id, attr_span, "target_feature");
-            }
-            _ => {
-                self.dcx().emit_err(errors::AttrShouldBeAppliedToFn {
-                    attr_span,
-                    defn_span: span,
-                    on_crate: hir_id == CRATE_HIR_ID,
-                });
-            }
+            _ => {}
         }
     }
 
@@ -1057,7 +812,10 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
             | Target::GenericParam { .. }
             | Target::MacroDef
             | Target::PatField
-            | Target::ExprField => None,
+            | Target::ExprField
+            | Target::Crate
+            | Target::MacroCall
+            | Target::Delegation { .. } => None,
         } {
             tcx.dcx().emit_err(errors::DocAliasBadLocation { span, attr_str, location });
             return;
@@ -1110,7 +868,12 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    fn check_doc_keyword(&self, meta: &MetaItemInner, hir_id: HirId) {
+    fn check_doc_keyword_and_attribute(
+        &self,
+        meta: &MetaItemInner,
+        hir_id: HirId,
+        attr_kind: DocFakeItemKind,
+    ) {
         fn is_doc_keyword(s: Symbol) -> bool {
             // FIXME: Once rustdoc can handle URL conflicts on case insensitive file systems, we
             // can remove the `SelfTy` case here, remove `sym::SelfTy`, and update the
@@ -1118,9 +881,14 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
             s.is_reserved(|| edition::LATEST_STABLE_EDITION) || s.is_weak() || s == sym::SelfTy
         }
 
-        let doc_keyword = match meta.value_str() {
+        // FIXME: This should support attributes with namespace like `diagnostic::do_not_recommend`.
+        fn is_builtin_attr(s: Symbol) -> bool {
+            rustc_feature::BUILTIN_ATTRIBUTE_MAP.contains_key(&s)
+        }
+
+        let value = match meta.value_str() {
             Some(value) if value != sym::empty => value,
-            _ => return self.doc_attr_str_error(meta, "keyword"),
+            _ => return self.doc_attr_str_error(meta, attr_kind.name()),
         };
 
         let item_kind = match self.tcx.hir_node(hir_id) {
@@ -1130,20 +898,38 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         match item_kind {
             Some(ItemKind::Mod(_, module)) => {
                 if !module.item_ids.is_empty() {
-                    self.dcx().emit_err(errors::DocKeywordEmptyMod { span: meta.span() });
+                    self.dcx().emit_err(errors::DocKeywordAttributeEmptyMod {
+                        span: meta.span(),
+                        attr_name: attr_kind.name(),
+                    });
                     return;
                 }
             }
             _ => {
-                self.dcx().emit_err(errors::DocKeywordNotMod { span: meta.span() });
+                self.dcx().emit_err(errors::DocKeywordAttributeNotMod {
+                    span: meta.span(),
+                    attr_name: attr_kind.name(),
+                });
                 return;
             }
         }
-        if !is_doc_keyword(doc_keyword) {
-            self.dcx().emit_err(errors::DocKeywordNotKeyword {
-                span: meta.name_value_literal_span().unwrap_or_else(|| meta.span()),
-                keyword: doc_keyword,
-            });
+        match attr_kind {
+            DocFakeItemKind::Keyword => {
+                if !is_doc_keyword(value) {
+                    self.dcx().emit_err(errors::DocKeywordNotKeyword {
+                        span: meta.name_value_literal_span().unwrap_or_else(|| meta.span()),
+                        keyword: value,
+                    });
+                }
+            }
+            DocFakeItemKind::Attribute => {
+                if !is_builtin_attr(value) {
+                    self.dcx().emit_err(errors::DocAttributeNotAttribute {
+                        span: meta.name_value_literal_span().unwrap_or_else(|| meta.span()),
+                        attribute: value,
+                    });
+                }
+            }
         }
     }
 
@@ -1403,7 +1189,21 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
 
                         Some(sym::keyword) => {
                             if self.check_attr_not_crate_level(meta, hir_id, "keyword") {
-                                self.check_doc_keyword(meta, hir_id);
+                                self.check_doc_keyword_and_attribute(
+                                    meta,
+                                    hir_id,
+                                    DocFakeItemKind::Keyword,
+                                );
+                            }
+                        }
+
+                        Some(sym::attribute) => {
+                            if self.check_attr_not_crate_level(meta, hir_id, "attribute") {
+                                self.check_doc_keyword_and_attribute(
+                                    meta,
+                                    hir_id,
+                                    DocFakeItemKind::Attribute,
+                                );
                             }
                         }
 
@@ -1533,25 +1333,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    /// Warns against some misuses of `#[pass_by_value]`
-    fn check_pass_by_value(&self, attr_span: Span, span: Span, target: Target) {
-        match target {
-            Target::Struct | Target::Enum | Target::TyAlias => {}
-            _ => {
-                self.dcx().emit_err(errors::PassByValue { attr_span, span });
-            }
-        }
-    }
-
-    fn check_allow_incoherent_impl(&self, attr_span: Span, span: Span, target: Target) {
-        match target {
-            Target::Method(MethodKind::Inherent) => {}
-            _ => {
-                self.dcx().emit_err(errors::AllowIncoherentImpl { attr_span, span });
-            }
-        }
-    }
-
     fn check_has_incoherent_inherent_impls(&self, attr: &Attribute, span: Span, target: Target) {
         match target {
             Target::Trait | Target::Struct | Target::Enum | Target::Union | Target::ForeignTy => {}
@@ -1563,69 +1344,13 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    fn check_ffi_pure(&self, attr_span: Span, attrs: &[Attribute], target: Target) {
-        if target != Target::ForeignFn {
-            self.dcx().emit_err(errors::FfiPureInvalidTarget { attr_span });
-            return;
-        }
+    fn check_ffi_pure(&self, attr_span: Span, attrs: &[Attribute]) {
         if find_attr!(attrs, AttributeKind::FfiConst(_)) {
             // `#[ffi_const]` functions cannot be `#[ffi_pure]`
             self.dcx().emit_err(errors::BothFfiConstAndPure { attr_span });
         }
     }
 
-    fn check_ffi_const(&self, attr_span: Span, target: Target) {
-        if target != Target::ForeignFn {
-            self.dcx().emit_err(errors::FfiConstInvalidTarget { attr_span });
-        }
-    }
-
-    /// Warns against some misuses of `#[must_use]`
-    fn check_must_use(&self, hir_id: HirId, attr_span: Span, target: Target) {
-        if matches!(
-            target,
-            Target::Fn
-                | Target::Enum
-                | Target::Struct
-                | Target::Union
-                | Target::Method(MethodKind::Trait { body: false } | MethodKind::Inherent)
-                | Target::ForeignFn
-                // `impl Trait` in return position can trip
-                // `unused_must_use` if `Trait` is marked as
-                // `#[must_use]`
-                | Target::Trait
-        ) {
-            return;
-        }
-
-        // `#[must_use]` can be applied to a trait method definition with a default body
-        if let Target::Method(MethodKind::Trait { body: true }) = target
-            && let parent_def_id = self.tcx.hir_get_parent_item(hir_id).def_id
-            && let containing_item = self.tcx.hir_expect_item(parent_def_id)
-            && let hir::ItemKind::Trait(..) = containing_item.kind
-        {
-            return;
-        }
-
-        let article = match target {
-            Target::ExternCrate
-            | Target::Enum
-            | Target::Impl { .. }
-            | Target::Expression
-            | Target::Arm
-            | Target::AssocConst
-            | Target::AssocTy => "an",
-            _ => "a",
-        };
-
-        self.tcx.emit_node_span_lint(
-            UNUSED_ATTRIBUTES,
-            hir_id,
-            attr_span,
-            errors::MustUseNoEffect { article, target },
-        );
-    }
-
     /// Checks if `#[must_not_suspend]` is applied to a struct, enum, union, or trait.
     fn check_must_not_suspend(&self, attr: &Attribute, span: Span, target: Target) {
         match target {
@@ -1657,32 +1382,8 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         self.dcx().emit_err(errors::InvalidMayDangle { attr_span });
     }
 
-    /// Checks if `#[cold]` is applied to a non-function.
-    fn check_cold(&self, hir_id: HirId, attr_span: Span, span: Span, target: Target) {
-        match target {
-            Target::Fn | Target::Method(..) | Target::ForeignFn | Target::Closure => {}
-            // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
-            // `#[cold]` attribute with just a lint, because we previously
-            // erroneously allowed it and some crates used it accidentally, to be compatible
-            // with crates depending on them, we can't throw an error here.
-            Target::Field | Target::Arm | Target::MacroDef => {
-                self.inline_attr_str_error_with_macro_def(hir_id, attr_span, "cold");
-            }
-            _ => {
-                // FIXME: #[cold] was previously allowed on non-functions and some crates used
-                // this, so only emit a warning.
-                self.tcx.emit_node_span_lint(
-                    UNUSED_ATTRIBUTES,
-                    hir_id,
-                    attr_span,
-                    errors::Cold { span, on_crate: hir_id == CRATE_HIR_ID },
-                );
-            }
-        }
-    }
-
     /// Checks if `#[link]` is applied to an item other than a foreign module.
-    fn check_link(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
+    fn check_link(&self, hir_id: HirId, attr_span: Span, span: Span, target: Target) {
         if target == Target::ForeignMod
             && let hir::Node::Item(item) = self.tcx.hir_node(hir_id)
             && let Item { kind: ItemKind::ForeignMod { abi, .. }, .. } = item
@@ -1694,43 +1395,11 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         self.tcx.emit_node_span_lint(
             UNUSED_ATTRIBUTES,
             hir_id,
-            attr.span(),
+            attr_span,
             errors::Link { span: (target != Target::ForeignMod).then_some(span) },
         );
     }
 
-    /// Checks if `#[link_name]` is applied to an item other than a foreign function or static.
-    fn check_link_name(
-        &self,
-        hir_id: HirId,
-        attr_span: Span,
-        name: Symbol,
-        span: Span,
-        target: Target,
-    ) {
-        match target {
-            Target::ForeignFn | Target::ForeignStatic => {}
-            // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
-            // `#[link_name]` attribute with just a lint, because we previously
-            // erroneously allowed it and some crates used it accidentally, to be compatible
-            // with crates depending on them, we can't throw an error here.
-            Target::Field | Target::Arm | Target::MacroDef => {
-                self.inline_attr_str_error_with_macro_def(hir_id, attr_span, "link_name");
-            }
-            _ => {
-                // FIXME: #[link_name] was previously allowed on non-functions/statics and some crates
-                // used this, so only emit a warning.
-                let help_span = matches!(target, Target::ForeignMod).then_some(attr_span);
-                self.tcx.emit_node_span_lint(
-                    UNUSED_ATTRIBUTES,
-                    hir_id,
-                    attr_span,
-                    errors::LinkName { span, help_span, value: name.as_str() },
-                );
-            }
-        }
-    }
-
     /// Checks if `#[no_link]` is applied to an `extern crate`.
     fn check_no_link(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
         match target {
@@ -1748,35 +1417,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    fn is_impl_item(&self, hir_id: HirId) -> bool {
-        matches!(self.tcx.hir_node(hir_id), hir::Node::ImplItem(..))
-    }
-
-    /// Checks if `#[export_name]` is applied to a function or static.
-    fn check_export_name(&self, hir_id: HirId, attr_span: Span, span: Span, target: Target) {
-        match target {
-            Target::Static | Target::Fn => {}
-            Target::Method(..) if self.is_impl_item(hir_id) => {}
-            // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
-            // `#[export_name]` attribute with just a lint, because we previously
-            // erroneously allowed it and some crates used it accidentally, to be compatible
-            // with crates depending on them, we can't throw an error here.
-            Target::Field | Target::Arm | Target::MacroDef => {
-                self.inline_attr_str_error_with_macro_def(hir_id, attr_span, "export_name");
-            }
-            _ => {
-                self.dcx().emit_err(errors::ExportName { attr_span, span });
-            }
-        }
-    }
-
-    fn check_rustc_layout_scalar_valid_range(&self, attr_span: Span, span: Span, target: Target) {
-        if target != Target::Struct {
-            self.dcx().emit_err(errors::RustcLayoutScalarValidRangeNotStruct { attr_span, span });
-            return;
-        }
-    }
-
     /// Checks if `#[rustc_legacy_const_generics]` is applied to a function and has a valid argument.
     fn check_rustc_legacy_const_generics(
         &self,
@@ -1911,106 +1551,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    /// Checks if `#[link_section]` is applied to a function or static.
-    fn check_link_section(&self, hir_id: HirId, attr_span: Span, span: Span, target: Target) {
-        match target {
-            Target::Static | Target::Fn | Target::Method(..) => {}
-            // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
-            // `#[link_section]` attribute with just a lint, because we previously
-            // erroneously allowed it and some crates used it accidentally, to be compatible
-            // with crates depending on them, we can't throw an error here.
-            Target::Field | Target::Arm | Target::MacroDef => {
-                self.inline_attr_str_error_with_macro_def(hir_id, attr_span, "link_section");
-            }
-            _ => {
-                // FIXME: #[link_section] was previously allowed on non-functions/statics and some
-                // crates used this, so only emit a warning.
-                self.tcx.emit_node_span_lint(
-                    UNUSED_ATTRIBUTES,
-                    hir_id,
-                    attr_span,
-                    errors::LinkSection { span },
-                );
-            }
-        }
-    }
-
-    /// Checks if `#[no_mangle]` is applied to a function or static.
-    fn check_no_mangle(&self, hir_id: HirId, attr_span: Span, span: Span, target: Target) {
-        match target {
-            Target::Static | Target::Fn => {}
-            Target::Method(..) if self.is_impl_item(hir_id) => {}
-            // FIXME(#80564): We permit struct fields, match arms and macro defs to have an
-            // `#[no_mangle]` attribute with just a lint, because we previously
-            // erroneously allowed it and some crates used it accidentally, to be compatible
-            // with crates depending on them, we can't throw an error here.
-            Target::Field | Target::Arm | Target::MacroDef => {
-                self.inline_attr_str_error_with_macro_def(hir_id, attr_span, "no_mangle");
-            }
-            // FIXME: #[no_mangle] was previously allowed on non-functions/statics, this should be an error
-            // The error should specify that the item that is wrong is specifically a *foreign* fn/static
-            // otherwise the error seems odd
-            Target::ForeignFn | Target::ForeignStatic => {
-                let foreign_item_kind = match target {
-                    Target::ForeignFn => "function",
-                    Target::ForeignStatic => "static",
-                    _ => unreachable!(),
-                };
-                self.tcx.emit_node_span_lint(
-                    UNUSED_ATTRIBUTES,
-                    hir_id,
-                    attr_span,
-                    errors::NoMangleForeign { span, attr_span, foreign_item_kind },
-                );
-            }
-            _ => {
-                // FIXME: #[no_mangle] was previously allowed on non-functions/statics and some
-                // crates used this, so only emit a warning.
-                self.tcx.emit_node_span_lint(
-                    UNUSED_ATTRIBUTES,
-                    hir_id,
-                    attr_span,
-                    errors::NoMangle { span },
-                );
-            }
-        }
-    }
-
-    /// Checks if the `#[align]` attributes on `item` are valid.
-    // FIXME(#82232, #143834): temporarily renamed to mitigate `#[align]` nameres ambiguity
-    fn check_align(
-        &self,
-        span: Span,
-        hir_id: HirId,
-        target: Target,
-        align: Align,
-        attr_span: Span,
-    ) {
-        match target {
-            Target::Fn | Target::Method(_) | Target::ForeignFn => {}
-            Target::Field => {
-                self.tcx.emit_node_span_lint(
-                    UNUSED_ATTRIBUTES,
-                    hir_id,
-                    attr_span,
-                    AlignOnFields { span },
-                );
-            }
-            Target::Struct | Target::Union | Target::Enum => {
-                self.dcx().emit_err(errors::AlignShouldBeReprAlign {
-                    span: attr_span,
-                    item: target.name(),
-                    align_bytes: align.bytes(),
-                });
-            }
-            _ => {
-                self.dcx().emit_err(errors::AlignAttrApplication { hint_span: attr_span, span });
-            }
-        }
-
-        self.check_align_value(align, attr_span);
-    }
-
     /// Checks if the `#[repr]` attributes on `item` are valid.
     fn check_repr(
         &self,
@@ -2065,7 +1605,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                         Target::Fn | Target::Method(_) => {
                             self.dcx().emit_err(errors::ReprAlignShouldBeAlign {
                                 span: *repr_span,
-                                item: target.name(),
+                                item: target.plural_name(),
                             });
                         }
                         _ => {
@@ -2076,7 +1616,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                         }
                     }
 
-                    self.check_align_value(*align, *repr_span);
+                    self.check_align(*align, *repr_span);
                 }
                 ReprAttr::ReprPacked(_) => {
                     if target != Target::Struct && target != Target::Union {
@@ -2135,7 +1675,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 Target::Fn | Target::Method(_) => {
                     self.dcx().emit_err(errors::ReprAlignShouldBeAlign {
                         span: first_attr_span,
-                        item: target.name(),
+                        item: target.plural_name(),
                     });
                 }
                 _ => {
@@ -2182,7 +1722,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    fn check_align_value(&self, align: Align, span: Span) {
+    fn check_align(&self, align: Align, span: Span) {
         if align.bytes() > 2_u64.pow(29) {
             // for values greater than 2^29, a different error will be emitted, make sure that happens
             self.dcx().span_delayed_bug(
@@ -2201,61 +1741,16 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    fn check_used(&self, attr_span: Span, target: Target, target_span: Span) {
-        if target != Target::Static {
-            self.dcx().emit_err(errors::UsedStatic {
-                attr_span,
-                span: target_span,
-                target: target.name(),
-            });
-        }
-    }
-
-    /// Outputs an error for `#[allow_internal_unstable]` which can only be applied to macros.
-    /// (Allows proc_macro functions)
-    fn check_allow_internal_unstable(
-        &self,
-        hir_id: HirId,
-        attr_span: Span,
-        span: Span,
-        target: Target,
-        attrs: &[Attribute],
-    ) {
-        self.check_macro_only_attr(
-            hir_id,
-            attr_span,
-            span,
-            target,
-            attrs,
-            "allow_internal_unstable",
-        )
-    }
-
-    /// Outputs an error for `#[allow_internal_unsafe]` which can only be applied to macros.
-    /// (Allows proc_macro functions)
-    fn check_allow_internal_unsafe(
-        &self,
-        hir_id: HirId,
-        attr_span: Span,
-        span: Span,
-        target: Target,
-        attrs: &[Attribute],
-    ) {
-        self.check_macro_only_attr(hir_id, attr_span, span, target, attrs, "allow_internal_unsafe")
-    }
-
     /// Outputs an error for attributes that can only be applied to macros, such as
     /// `#[allow_internal_unsafe]` and `#[allow_internal_unstable]`.
     /// (Allows proc_macro functions)
     // FIXME(jdonszelmann): if possible, move to attr parsing
     fn check_macro_only_attr(
         &self,
-        hir_id: HirId,
         attr_span: Span,
         span: Span,
         target: Target,
         attrs: &[Attribute],
-        attr_name: &str,
     ) {
         match target {
             Target::Fn => {
@@ -2265,23 +1760,10 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                         return;
                     }
                 }
-                // continue out of the match
-            }
-            // return on decl macros
-            Target::MacroDef => return,
-            // FIXME(#80564): We permit struct fields and match arms to have an
-            // `#[allow_internal_unstable]` attribute with just a lint, because we previously
-            // erroneously allowed it and some crates used it accidentally, to be compatible
-            // with crates depending on them, we can't throw an error here.
-            Target::Field | Target::Arm => {
-                self.inline_attr_str_error_without_macro_def(hir_id, attr_span, attr_name);
-                return;
+                self.tcx.dcx().emit_err(errors::MacroOnlyAttribute { attr_span, span });
             }
-            // otherwise continue out of the match
             _ => {}
         }
-
-        self.tcx.dcx().emit_err(errors::MacroOnlyAttribute { attr_span, span });
     }
 
     /// Checks if the items on the `#[debugger_visualizer]` attribute are valid.
@@ -2308,66 +1790,12 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         target: Target,
     ) {
         match target {
-            Target::Fn | Target::Method(_)
-                if self.tcx.is_const_fn(hir_id.expect_owner().to_def_id()) => {}
-            // FIXME(#80564): We permit struct fields and match arms to have an
-            // `#[allow_internal_unstable]` attribute with just a lint, because we previously
-            // erroneously allowed it and some crates used it accidentally, to be compatible
-            // with crates depending on them, we can't throw an error here.
-            Target::Field | Target::Arm | Target::MacroDef => self
-                .inline_attr_str_error_with_macro_def(hir_id, attr_span, "allow_internal_unstable"),
-            _ => {
-                self.tcx.dcx().emit_err(errors::RustcAllowConstFnUnstable { attr_span, span });
-            }
-        }
-    }
-
-    fn check_unstable_feature_bound(&self, attr_span: Span, span: Span, target: Target) {
-        match target {
-            // FIXME(staged_api): There's no reason we can't support more targets here. We're just
-            // being conservative to begin with.
-            Target::Fn | Target::Impl { .. } | Target::Trait => {}
-            Target::ExternCrate
-            | Target::Use
-            | Target::Static
-            | Target::Const
-            | Target::Closure
-            | Target::Mod
-            | Target::ForeignMod
-            | Target::GlobalAsm
-            | Target::TyAlias
-            | Target::Enum
-            | Target::Variant
-            | Target::Struct
-            | Target::Field
-            | Target::Union
-            | Target::TraitAlias
-            | Target::Expression
-            | Target::Statement
-            | Target::Arm
-            | Target::AssocConst
-            | Target::Method(_)
-            | Target::AssocTy
-            | Target::ForeignFn
-            | Target::ForeignStatic
-            | Target::ForeignTy
-            | Target::GenericParam { .. }
-            | Target::MacroDef
-            | Target::Param
-            | Target::PatField
-            | Target::ExprField
-            | Target::WherePredicate => {
-                self.tcx.dcx().emit_err(errors::RustcUnstableFeatureBound { attr_span, span });
-            }
-        }
-    }
-
-    fn check_rustc_std_internal_symbol(&self, attr_span: Span, span: Span, target: Target) {
-        match target {
-            Target::Fn | Target::Static | Target::ForeignFn | Target::ForeignStatic => {}
-            _ => {
-                self.tcx.dcx().emit_err(errors::RustcStdInternalSymbol { attr_span, span });
+            Target::Fn | Target::Method(_) => {
+                if !self.tcx.is_const_fn(hir_id.expect_owner().to_def_id()) {
+                    self.tcx.dcx().emit_err(errors::RustcAllowConstFnUnstable { attr_span, span });
+                }
             }
+            _ => {}
         }
     }
 
@@ -2377,15 +1805,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         item_span: Span,
         level: &StabilityLevel,
         feature: Symbol,
-        target: Target,
     ) {
-        match target {
-            Target::Expression => {
-                self.dcx().emit_err(errors::StabilityPromotable { attr_span });
-            }
-            _ => {}
-        }
-
         // Stable *language* features shouldn't be used as unstable library features.
         // (Not doing this for stable library features is checked by tidy.)
         if level.is_unstable()
@@ -2397,40 +1817,8 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    fn check_link_ordinal(&self, attr_span: Span, _span: Span, target: Target) {
-        match target {
-            Target::ForeignFn | Target::ForeignStatic => {}
-            _ => {
-                self.dcx().emit_err(errors::LinkOrdinal { attr_span });
-            }
-        }
-    }
-
-    fn check_confusables(&self, span: Span, target: Target) {
-        if !matches!(target, Target::Method(MethodKind::Inherent)) {
-            self.dcx().emit_err(errors::Confusables { attr_span: span });
-        }
-    }
-
     fn check_deprecated(&self, hir_id: HirId, attr: &Attribute, _span: Span, target: Target) {
         match target {
-            Target::Closure | Target::Expression | Target::Statement | Target::Arm => {
-                self.tcx.emit_node_span_lint(
-                    UNUSED_ATTRIBUTES,
-                    hir_id,
-                    attr.span(),
-                    errors::Deprecated,
-                );
-            }
-            Target::Impl { of_trait: true }
-            | Target::GenericParam { has_default: false, kind: _ } => {
-                self.tcx.emit_node_span_lint(
-                    USELESS_DEPRECATED,
-                    hir_id,
-                    attr.span(),
-                    errors::DeprecatedAnnotationHasNoEffect { span: attr.span() },
-                );
-            }
             Target::AssocConst | Target::Method(..) | Target::AssocTy
                 if matches!(
                     self.tcx.def_kind(self.tcx.local_parent(hir_id.owner.def_id)),
@@ -2438,7 +1826,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                 ) =>
             {
                 self.tcx.emit_node_span_lint(
-                    USELESS_DEPRECATED,
+                    UNUSED_ATTRIBUTES,
                     hir_id,
                     attr.span(),
                     errors::DeprecatedAnnotationHasNoEffect { span: attr.span() },
@@ -2448,20 +1836,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    fn check_macro_use(&self, hir_id: HirId, name: Symbol, attr_span: Span, target: Target) {
-        match target {
-            Target::ExternCrate | Target::Mod => {}
-            _ => {
-                self.tcx.emit_node_span_lint(
-                    UNUSED_ATTRIBUTES,
-                    hir_id,
-                    attr_span,
-                    errors::MacroUse { name },
-                );
-            }
-        }
-    }
-
     fn check_macro_export(&self, hir_id: HirId, attr: &Attribute, target: Target) {
         if target != Target::MacroDef {
             self.tcx.emit_node_span_lint(
@@ -2533,12 +1907,24 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         {
             if hir_id != CRATE_HIR_ID {
                 match style {
-                    Some(ast::AttrStyle::Outer) => self.tcx.emit_node_span_lint(
-                        UNUSED_ATTRIBUTES,
-                        hir_id,
-                        attr.span(),
-                        errors::OuterCrateLevelAttr,
-                    ),
+                    Some(ast::AttrStyle::Outer) => {
+                        let attr_span = attr.span();
+                        let bang_position = self
+                            .tcx
+                            .sess
+                            .source_map()
+                            .span_until_char(attr_span, '[')
+                            .shrink_to_hi();
+
+                        self.tcx.emit_node_span_lint(
+                            UNUSED_ATTRIBUTES,
+                            hir_id,
+                            attr_span,
+                            errors::OuterCrateLevelAttr {
+                                suggestion: errors::OuterCrateLevelAttrSuggestion { bang_position },
+                            },
+                        )
+                    }
                     Some(ast::AttrStyle::Inner) | None => self.tcx.emit_node_span_lint(
                         UNUSED_ATTRIBUTES,
                         hir_id,
@@ -2681,15 +2067,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    fn check_coroutine(&self, attr_span: Span, target: Target) {
-        match target {
-            Target::Closure => return,
-            _ => {
-                self.dcx().emit_err(errors::CoroutineOnNonClosure { span: attr_span });
-            }
-        }
-    }
-
     fn check_type_const(&self, hir_id: HirId, attr_span: Span, target: Target) {
         let tcx = self.tcx;
         if target == Target::AssocConst
@@ -2707,19 +2084,6 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    fn check_linkage(&self, attr: &Attribute, span: Span, target: Target) {
-        match target {
-            Target::Fn
-            | Target::Method(..)
-            | Target::Static
-            | Target::ForeignStatic
-            | Target::ForeignFn => {}
-            _ => {
-                self.dcx().emit_err(errors::Linkage { attr_span: attr.span(), span });
-            }
-        }
-    }
-
     fn check_rustc_pub_transparent(&self, attr_span: Span, span: Span, attrs: &[Attribute]) {
         if !find_attr!(attrs, AttributeKind::Repr { reprs, .. } => reprs.iter().any(|(r, _)| r == &ReprAttr::ReprTransparent))
             .unwrap_or(false)
@@ -2728,43 +2092,28 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
     }
 
-    fn check_rustc_force_inline(
-        &self,
-        hir_id: HirId,
-        attrs: &[Attribute],
-        span: Span,
-        target: Target,
-    ) {
-        match (
+    fn check_rustc_force_inline(&self, hir_id: HirId, attrs: &[Attribute], target: Target) {
+        if let (Target::Closure, None) = (
             target,
             find_attr!(attrs, AttributeKind::Inline(InlineAttr::Force { attr_span, .. }, _) => *attr_span),
         ) {
-            (Target::Closure, None) => {
-                let is_coro = matches!(
-                    self.tcx.hir_expect_expr(hir_id).kind,
-                    hir::ExprKind::Closure(hir::Closure {
-                        kind: hir::ClosureKind::Coroutine(..)
-                            | hir::ClosureKind::CoroutineClosure(..),
-                        ..
-                    })
-                );
-                let parent_did = self.tcx.hir_get_parent_item(hir_id).to_def_id();
-                let parent_span = self.tcx.def_span(parent_did);
+            let is_coro = matches!(
+                self.tcx.hir_expect_expr(hir_id).kind,
+                hir::ExprKind::Closure(hir::Closure {
+                    kind: hir::ClosureKind::Coroutine(..) | hir::ClosureKind::CoroutineClosure(..),
+                    ..
+                })
+            );
+            let parent_did = self.tcx.hir_get_parent_item(hir_id).to_def_id();
+            let parent_span = self.tcx.def_span(parent_did);
 
-                if let Some(attr_span) = find_attr!(
-                    self.tcx.get_all_attrs(parent_did),
-                    AttributeKind::Inline(InlineAttr::Force { attr_span, .. }, _) => *attr_span
-                ) && is_coro
-                {
-                    self.dcx()
-                        .emit_err(errors::RustcForceInlineCoro { attr_span, span: parent_span });
-                }
-            }
-            (Target::Fn, _) => (),
-            (_, Some(attr_span)) => {
-                self.dcx().emit_err(errors::RustcForceInline { attr_span, span });
+            if let Some(attr_span) = find_attr!(
+                self.tcx.get_all_attrs(parent_did),
+                AttributeKind::Inline(InlineAttr::Force { attr_span, .. }, _) => *attr_span
+            ) && is_coro
+            {
+                self.dcx().emit_err(errors::RustcForceInlineCoro { attr_span, span: parent_span });
             }
-            (_, None) => (),
         }
     }
 
@@ -2814,8 +2163,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         let node_span = self.tcx.hir_span(hir_id);
 
         if !matches!(target, Target::Expression) {
-            self.dcx().emit_err(errors::LoopMatchAttr { attr_span, node_span });
-            return;
+            return; // Handled in target checking during attr parse
         }
 
         if !matches!(self.tcx.hir_expect_expr(hir_id).kind, hir::ExprKind::Loop(..)) {
@@ -2827,14 +2175,55 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         let node_span = self.tcx.hir_span(hir_id);
 
         if !matches!(target, Target::Expression) {
-            self.dcx().emit_err(errors::ConstContinueAttr { attr_span, node_span });
-            return;
+            return; // Handled in target checking during attr parse
         }
 
         if !matches!(self.tcx.hir_expect_expr(hir_id).kind, hir::ExprKind::Break(..)) {
             self.dcx().emit_err(errors::ConstContinueAttr { attr_span, node_span });
         };
     }
+
+    fn check_custom_mir(
+        &self,
+        dialect: Option<(MirDialect, Span)>,
+        phase: Option<(MirPhase, Span)>,
+        attr_span: Span,
+    ) {
+        let Some((dialect, dialect_span)) = dialect else {
+            if let Some((_, phase_span)) = phase {
+                self.dcx()
+                    .emit_err(errors::CustomMirPhaseRequiresDialect { attr_span, phase_span });
+            }
+            return;
+        };
+
+        match dialect {
+            MirDialect::Analysis => {
+                if let Some((MirPhase::Optimized, phase_span)) = phase {
+                    self.dcx().emit_err(errors::CustomMirIncompatibleDialectAndPhase {
+                        dialect,
+                        phase: MirPhase::Optimized,
+                        attr_span,
+                        dialect_span,
+                        phase_span,
+                    });
+                }
+            }
+
+            MirDialect::Built => {
+                if let Some((phase, phase_span)) = phase {
+                    self.dcx().emit_err(errors::CustomMirIncompatibleDialectAndPhase {
+                        dialect,
+                        phase,
+                        attr_span,
+                        dialect_span,
+                        phase_span,
+                    });
+                }
+            }
+            MirDialect::Runtime => {}
+        }
+    }
 }
 
 impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> {
@@ -2871,6 +2260,7 @@ impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> {
             .hir_attrs(where_predicate.hir_id)
             .iter()
             .filter(|attr| !ATTRS_ALLOWED.iter().any(|&sym| attr.has_name(sym)))
+            .filter(|attr| !attr.is_parsed_attr())
             .map(|attr| attr.span())
             .collect::<Vec<_>>();
         if !spans.is_empty() {
@@ -3001,10 +2391,6 @@ fn check_invalid_crate_level_attr(tcx: TyCtxt<'_>, attrs: &[Attribute]) {
         }) = attr
         {
             (*first_attr_span, sym::repr)
-        } else if let Attribute::Parsed(AttributeKind::Path(.., span)) = attr {
-            (*span, sym::path)
-        } else if let Attribute::Parsed(AttributeKind::AutomaticallyDerived(span)) = attr {
-            (*span, sym::automatically_derived)
         } else {
             continue;
         };
diff --git a/compiler/rustc_passes/src/dead.rs b/compiler/rustc_passes/src/dead.rs
index d5d7cc5dc2e..fc33405d455 100644
--- a/compiler/rustc_passes/src/dead.rs
+++ b/compiler/rustc_passes/src/dead.rs
@@ -8,7 +8,6 @@ use std::mem;
 use hir::def_id::{LocalDefIdMap, LocalDefIdSet};
 use rustc_abi::FieldIdx;
 use rustc_data_structures::fx::FxIndexSet;
-use rustc_data_structures::unord::UnordSet;
 use rustc_errors::MultiSpan;
 use rustc_hir::def::{CtorOf, DefKind, Res};
 use rustc_hir::def_id::{DefId, LocalDefId, LocalModDefId};
@@ -79,7 +78,7 @@ struct MarkSymbolVisitor<'tcx> {
     worklist: Vec<(LocalDefId, ComesFromAllowExpect)>,
     tcx: TyCtxt<'tcx>,
     maybe_typeck_results: Option<&'tcx ty::TypeckResults<'tcx>>,
-    scanned: UnordSet<(LocalDefId, ComesFromAllowExpect)>,
+    scanned: LocalDefIdSet,
     live_symbols: LocalDefIdSet,
     repr_unconditionally_treats_fields_as_live: bool,
     repr_has_repr_simd: bool,
@@ -321,18 +320,8 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {
 
     fn mark_live_symbols(&mut self) {
         while let Some(work) = self.worklist.pop() {
-            if !self.scanned.insert(work) {
-                continue;
-            }
-
             let (mut id, comes_from_allow_expect) = work;
 
-            // Avoid accessing the HIR for the synthesized associated type generated for RPITITs.
-            if self.tcx.is_impl_trait_in_trait(id.to_def_id()) {
-                self.live_symbols.insert(id);
-                continue;
-            }
-
             // in the case of tuple struct constructors we want to check the item,
             // not the generated tuple struct constructor function
             if let DefKind::Ctor(..) = self.tcx.def_kind(id) {
@@ -360,9 +349,23 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {
             // this "duplication" is essential as otherwise a function with `#[expect]`
             // called from a `pub fn` may be falsely reported as not live, falsely
             // triggering the `unfulfilled_lint_expectations` lint.
-            if comes_from_allow_expect != ComesFromAllowExpect::Yes {
+            match comes_from_allow_expect {
+                ComesFromAllowExpect::Yes => {}
+                ComesFromAllowExpect::No => {
+                    self.live_symbols.insert(id);
+                }
+            }
+
+            if !self.scanned.insert(id) {
+                continue;
+            }
+
+            // Avoid accessing the HIR for the synthesized associated type generated for RPITITs.
+            if self.tcx.is_impl_trait_in_trait(id.to_def_id()) {
                 self.live_symbols.insert(id);
+                continue;
             }
+
             self.visit_node(self.tcx.hir_node_by_def_id(id));
         }
     }
@@ -371,7 +374,7 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {
     /// will be ignored for the purposes of dead code analysis (see PR #85200
     /// for discussion).
     fn should_ignore_item(&mut self, def_id: DefId) -> bool {
-        if let Some(impl_of) = self.tcx.impl_of_assoc(def_id) {
+        if let Some(impl_of) = self.tcx.trait_impl_of_assoc(def_id) {
             if !self.tcx.is_automatically_derived(impl_of) {
                 return false;
             }
diff --git a/compiler/rustc_passes/src/errors.rs b/compiler/rustc_passes/src/errors.rs
index 10b30fbe8c9..680e2a26d84 100644
--- a/compiler/rustc_passes/src/errors.rs
+++ b/compiler/rustc_passes/src/errors.rs
@@ -7,6 +7,7 @@ use rustc_errors::{
     MultiSpan, Subdiagnostic,
 };
 use rustc_hir::Target;
+use rustc_hir::attrs::{MirDialect, MirPhase};
 use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
 use rustc_middle::ty::{MainDefinition, Ty};
 use rustc_span::{DUMMY_SP, Span, Symbol};
@@ -63,7 +64,17 @@ pub(crate) struct MixedExportNameAndNoMangle {
 
 #[derive(LintDiagnostic)]
 #[diag(passes_outer_crate_level_attr)]
-pub(crate) struct OuterCrateLevelAttr;
+pub(crate) struct OuterCrateLevelAttr {
+    #[subdiagnostic]
+    pub suggestion: OuterCrateLevelAttrSuggestion,
+}
+
+#[derive(Subdiagnostic)]
+#[multipart_suggestion(passes_outer_crate_level_attr_suggestion, style = "verbose")]
+pub(crate) struct OuterCrateLevelAttrSuggestion {
+    #[suggestion_part(code = "!")]
+    pub bang_position: Span,
+}
 
 #[derive(LintDiagnostic)]
 #[diag(passes_inner_crate_level_attr)]
@@ -75,58 +86,6 @@ pub(crate) struct IgnoredAttrWithMacro<'a> {
     pub sym: &'a str,
 }
 
-#[derive(LintDiagnostic)]
-#[diag(passes_ignored_attr)]
-pub(crate) struct IgnoredAttr<'a> {
-    pub sym: &'a str,
-}
-
-#[derive(LintDiagnostic)]
-#[diag(passes_inline_ignored_function_prototype)]
-pub(crate) struct IgnoredInlineAttrFnProto;
-
-#[derive(LintDiagnostic)]
-#[diag(passes_inline_ignored_constants)]
-#[warning]
-#[note]
-pub(crate) struct IgnoredInlineAttrConstants;
-
-#[derive(Diagnostic)]
-#[diag(passes_inline_not_fn_or_closure, code = E0518)]
-pub(crate) struct InlineNotFnOrClosure {
-    #[primary_span]
-    pub attr_span: Span,
-    #[label]
-    pub defn_span: Span,
-}
-
-/// "coverage attribute not allowed here"
-#[derive(Diagnostic)]
-#[diag(passes_coverage_attribute_not_allowed, code = E0788)]
-pub(crate) struct CoverageAttributeNotAllowed {
-    #[primary_span]
-    pub attr_span: Span,
-    /// "not a function, impl block, or module"
-    #[label(passes_not_fn_impl_mod)]
-    pub not_fn_impl_mod: Option<Span>,
-    /// "function has no body"
-    #[label(passes_no_body)]
-    pub no_body: Option<Span>,
-    /// "coverage attribute can be applied to a function (with body), impl block, or module"
-    #[help]
-    pub help: (),
-}
-
-#[derive(Diagnostic)]
-#[diag(passes_optimize_invalid_target)]
-pub(crate) struct OptimizeInvalidTarget {
-    #[primary_span]
-    pub attr_span: Span,
-    #[label]
-    pub defn_span: Span,
-    pub on_crate: bool,
-}
-
 #[derive(Diagnostic)]
 #[diag(passes_should_be_applied_to_fn)]
 pub(crate) struct AttrShouldBeAppliedToFn {
@@ -138,25 +97,6 @@ pub(crate) struct AttrShouldBeAppliedToFn {
 }
 
 #[derive(Diagnostic)]
-#[diag(passes_should_be_applied_to_fn, code = E0739)]
-pub(crate) struct TrackedCallerWrongLocation {
-    #[primary_span]
-    pub attr_span: Span,
-    #[label]
-    pub defn_span: Span,
-    pub on_crate: bool,
-}
-
-#[derive(Diagnostic)]
-#[diag(passes_should_be_applied_to_struct_enum, code = E0701)]
-pub(crate) struct NonExhaustiveWrongLocation {
-    #[primary_span]
-    pub attr_span: Span,
-    #[label]
-    pub defn_span: Span,
-}
-
-#[derive(Diagnostic)]
 #[diag(passes_non_exhaustive_with_default_field_values)]
 pub(crate) struct NonExhaustiveWithDefaultFieldValues {
     #[primary_span]
@@ -174,10 +114,6 @@ pub(crate) struct AttrShouldBeAppliedToTrait {
     pub defn_span: Span,
 }
 
-#[derive(LintDiagnostic)]
-#[diag(passes_target_feature_on_statement)]
-pub(crate) struct TargetFeatureOnStatement;
-
 #[derive(Diagnostic)]
 #[diag(passes_should_be_applied_to_static)]
 pub(crate) struct AttrShouldBeAppliedToStatic {
@@ -259,10 +195,11 @@ pub(crate) struct DocAliasMalformed {
 }
 
 #[derive(Diagnostic)]
-#[diag(passes_doc_keyword_empty_mod)]
-pub(crate) struct DocKeywordEmptyMod {
+#[diag(passes_doc_keyword_attribute_empty_mod)]
+pub(crate) struct DocKeywordAttributeEmptyMod {
     #[primary_span]
     pub span: Span,
+    pub attr_name: &'static str,
 }
 
 #[derive(Diagnostic)]
@@ -275,10 +212,20 @@ pub(crate) struct DocKeywordNotKeyword {
 }
 
 #[derive(Diagnostic)]
-#[diag(passes_doc_keyword_not_mod)]
-pub(crate) struct DocKeywordNotMod {
+#[diag(passes_doc_attribute_not_attribute)]
+#[help]
+pub(crate) struct DocAttributeNotAttribute {
+    #[primary_span]
+    pub span: Span,
+    pub attribute: Symbol,
+}
+
+#[derive(Diagnostic)]
+#[diag(passes_doc_keyword_attribute_not_mod)]
+pub(crate) struct DocKeywordAttributeNotMod {
     #[primary_span]
     pub span: Span,
+    pub attr_name: &'static str,
 }
 
 #[derive(Diagnostic)]
@@ -417,24 +364,6 @@ pub(crate) struct DocTestUnknownInclude {
 pub(crate) struct DocInvalid;
 
 #[derive(Diagnostic)]
-#[diag(passes_pass_by_value)]
-pub(crate) struct PassByValue {
-    #[primary_span]
-    pub attr_span: Span,
-    #[label]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(passes_allow_incoherent_impl)]
-pub(crate) struct AllowIncoherentImpl {
-    #[primary_span]
-    pub attr_span: Span,
-    #[label]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
 #[diag(passes_has_incoherent_inherent_impl)]
 pub(crate) struct HasIncoherentInherentImpl {
     #[primary_span]
@@ -451,27 +380,6 @@ pub(crate) struct BothFfiConstAndPure {
 }
 
 #[derive(Diagnostic)]
-#[diag(passes_ffi_pure_invalid_target, code = E0755)]
-pub(crate) struct FfiPureInvalidTarget {
-    #[primary_span]
-    pub attr_span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(passes_ffi_const_invalid_target, code = E0756)]
-pub(crate) struct FfiConstInvalidTarget {
-    #[primary_span]
-    pub attr_span: Span,
-}
-
-#[derive(LintDiagnostic)]
-#[diag(passes_must_use_no_effect)]
-pub(crate) struct MustUseNoEffect {
-    pub article: &'static str,
-    pub target: rustc_hir::Target,
-}
-
-#[derive(Diagnostic)]
 #[diag(passes_must_not_suspend)]
 pub(crate) struct MustNotSuspend {
     #[primary_span]
@@ -481,15 +389,6 @@ pub(crate) struct MustNotSuspend {
 }
 
 #[derive(LintDiagnostic)]
-#[diag(passes_cold)]
-#[warning]
-pub(crate) struct Cold {
-    #[label]
-    pub span: Span,
-    pub on_crate: bool,
-}
-
-#[derive(LintDiagnostic)]
 #[diag(passes_link)]
 #[warning]
 pub(crate) struct Link {
@@ -497,17 +396,6 @@ pub(crate) struct Link {
     pub span: Option<Span>,
 }
 
-#[derive(LintDiagnostic)]
-#[diag(passes_link_name)]
-#[warning]
-pub(crate) struct LinkName<'a> {
-    #[help]
-    pub help_span: Option<Span>,
-    #[label]
-    pub span: Span,
-    pub value: &'a str,
-}
-
 #[derive(Diagnostic)]
 #[diag(passes_no_link)]
 pub(crate) struct NoLink {
@@ -518,24 +406,6 @@ pub(crate) struct NoLink {
 }
 
 #[derive(Diagnostic)]
-#[diag(passes_export_name)]
-pub(crate) struct ExportName {
-    #[primary_span]
-    pub attr_span: Span,
-    #[label]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(passes_rustc_layout_scalar_valid_range_not_struct)]
-pub(crate) struct RustcLayoutScalarValidRangeNotStruct {
-    #[primary_span]
-    pub attr_span: Span,
-    #[label]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
 #[diag(passes_rustc_legacy_const_generics_only)]
 pub(crate) struct RustcLegacyConstGenericsOnly {
     #[primary_span]
@@ -576,42 +446,6 @@ pub(crate) struct RustcDirtyClean {
     pub span: Span,
 }
 
-#[derive(LintDiagnostic)]
-#[diag(passes_link_section)]
-#[warning]
-pub(crate) struct LinkSection {
-    #[label]
-    pub span: Span,
-}
-
-#[derive(LintDiagnostic)]
-#[diag(passes_no_mangle_foreign)]
-#[warning]
-#[note]
-pub(crate) struct NoMangleForeign {
-    #[label]
-    pub span: Span,
-    #[suggestion(code = "", applicability = "machine-applicable")]
-    pub attr_span: Span,
-    pub foreign_item_kind: &'static str,
-}
-
-#[derive(LintDiagnostic)]
-#[diag(passes_no_mangle)]
-#[warning]
-pub(crate) struct NoMangle {
-    #[label]
-    pub span: Span,
-}
-
-#[derive(LintDiagnostic)]
-#[diag(passes_align_on_fields)]
-#[warning]
-pub(crate) struct AlignOnFields {
-    #[label]
-    pub span: Span,
-}
-
 #[derive(Diagnostic)]
 #[diag(passes_repr_conflicting, code = E0566)]
 pub(crate) struct ReprConflicting {
@@ -633,16 +467,6 @@ pub(crate) struct InvalidReprAlignForTarget {
 pub(crate) struct ReprConflictingLint;
 
 #[derive(Diagnostic)]
-#[diag(passes_used_static)]
-pub(crate) struct UsedStatic {
-    #[primary_span]
-    pub attr_span: Span,
-    #[label]
-    pub span: Span,
-    pub target: &'static str,
-}
-
-#[derive(Diagnostic)]
 #[diag(passes_macro_only_attribute)]
 pub(crate) struct MacroOnlyAttribute {
     #[primary_span]
@@ -687,24 +511,6 @@ pub(crate) struct RustcAllowConstFnUnstable {
 }
 
 #[derive(Diagnostic)]
-#[diag(passes_rustc_unstable_feature_bound)]
-pub(crate) struct RustcUnstableFeatureBound {
-    #[primary_span]
-    pub attr_span: Span,
-    #[label]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(passes_rustc_std_internal_symbol)]
-pub(crate) struct RustcStdInternalSymbol {
-    #[primary_span]
-    pub attr_span: Span,
-    #[label]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
 #[diag(passes_rustc_pub_transparent)]
 pub(crate) struct RustcPubTransparent {
     #[primary_span]
@@ -714,15 +520,6 @@ pub(crate) struct RustcPubTransparent {
 }
 
 #[derive(Diagnostic)]
-#[diag(passes_rustc_force_inline)]
-pub(crate) struct RustcForceInline {
-    #[primary_span]
-    pub attr_span: Span,
-    #[label]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
 #[diag(passes_rustc_force_inline_coro)]
 pub(crate) struct RustcForceInlineCoro {
     #[primary_span]
@@ -731,53 +528,6 @@ pub(crate) struct RustcForceInlineCoro {
     pub span: Span,
 }
 
-#[derive(Diagnostic)]
-#[diag(passes_link_ordinal)]
-pub(crate) struct LinkOrdinal {
-    #[primary_span]
-    pub attr_span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(passes_confusables)]
-pub(crate) struct Confusables {
-    #[primary_span]
-    pub attr_span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(passes_coroutine_on_non_closure)]
-pub(crate) struct CoroutineOnNonClosure {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(passes_linkage)]
-pub(crate) struct Linkage {
-    #[primary_span]
-    pub attr_span: Span,
-    #[label]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(passes_stability_promotable)]
-pub(crate) struct StabilityPromotable {
-    #[primary_span]
-    pub attr_span: Span,
-}
-
-#[derive(LintDiagnostic)]
-#[diag(passes_deprecated)]
-pub(crate) struct Deprecated;
-
-#[derive(LintDiagnostic)]
-#[diag(passes_macro_use)]
-pub(crate) struct MacroUse {
-    pub name: Symbol,
-}
-
 #[derive(LintDiagnostic)]
 pub(crate) enum MacroExport {
     #[diag(passes_macro_export)]
@@ -1281,13 +1031,6 @@ pub(crate) struct UselessAssignment<'a> {
 }
 
 #[derive(LintDiagnostic)]
-#[diag(passes_only_has_effect_on)]
-pub(crate) struct OnlyHasEffectOn {
-    pub attr_name: String,
-    pub target_name: String,
-}
-
-#[derive(LintDiagnostic)]
 #[diag(passes_inline_ignored_for_exported)]
 #[help]
 pub(crate) struct InlineIgnoredForExported {}
@@ -1759,15 +1502,21 @@ pub(crate) struct AttrCrateLevelOnlySugg {
     pub attr: Span,
 }
 
+/// "sanitize attribute not allowed here"
 #[derive(Diagnostic)]
-#[diag(passes_no_sanitize)]
-pub(crate) struct NoSanitize<'a> {
+#[diag(passes_sanitize_attribute_not_allowed)]
+pub(crate) struct SanitizeAttributeNotAllowed {
     #[primary_span]
     pub attr_span: Span,
-    #[label]
-    pub defn_span: Span,
-    pub accepted_kind: &'a str,
-    pub attr_str: &'a str,
+    /// "not a function, impl block, or module"
+    #[label(passes_not_fn_impl_mod)]
+    pub not_fn_impl_mod: Option<Span>,
+    /// "function has no body"
+    #[label(passes_no_body)]
+    pub no_body: Option<Span>,
+    /// "sanitize attribute can be applied to a function (with body), impl block, or module"
+    #[help]
+    pub help: (),
 }
 
 // FIXME(jdonszelmann): move back to rustc_attr
@@ -1843,24 +1592,23 @@ pub(crate) struct ReprAlignShouldBeAlign {
 }
 
 #[derive(Diagnostic)]
-#[diag(passes_align_should_be_repr_align)]
-pub(crate) struct AlignShouldBeReprAlign {
+#[diag(passes_custom_mir_phase_requires_dialect)]
+pub(crate) struct CustomMirPhaseRequiresDialect {
     #[primary_span]
-    #[suggestion(
-        style = "verbose",
-        applicability = "machine-applicable",
-        code = "#[repr(align({align_bytes}))]"
-    )]
-    pub span: Span,
-    pub item: &'static str,
-    pub align_bytes: u64,
+    pub attr_span: Span,
+    #[label]
+    pub phase_span: Span,
 }
 
 #[derive(Diagnostic)]
-#[diag(passes_align_attr_application)]
-pub(crate) struct AlignAttrApplication {
+#[diag(passes_custom_mir_incompatible_dialect_and_phase)]
+pub(crate) struct CustomMirIncompatibleDialectAndPhase {
+    pub dialect: MirDialect,
+    pub phase: MirPhase,
     #[primary_span]
-    pub hint_span: Span,
+    pub attr_span: Span,
     #[label]
-    pub span: Span,
+    pub dialect_span: Span,
+    #[label]
+    pub phase_span: Span,
 }
diff --git a/compiler/rustc_passes/src/lang_items.rs b/compiler/rustc_passes/src/lang_items.rs
index 6fac01827a4..141a60a8ec3 100644
--- a/compiler/rustc_passes/src/lang_items.rs
+++ b/compiler/rustc_passes/src/lang_items.rs
@@ -329,7 +329,7 @@ impl<'ast, 'tcx> visit::Visitor<'ast> for LanguageItemCollector<'ast, 'tcx> {
                     match &self.parent_item.unwrap().kind {
                         ast::ItemKind::Impl(i) => {
                             if i.of_trait.is_some() {
-                                Target::Method(MethodKind::Trait { body })
+                                Target::Method(MethodKind::TraitImpl)
                             } else {
                                 Target::Method(MethodKind::Inherent)
                             }
diff --git a/compiler/rustc_passes/src/reachable.rs b/compiler/rustc_passes/src/reachable.rs
index 2f78c22c748..d1a703fc5d8 100644
--- a/compiler/rustc_passes/src/reachable.rs
+++ b/compiler/rustc_passes/src/reachable.rs
@@ -423,6 +423,7 @@ fn has_custom_linkage(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
     if !tcx.def_kind(def_id).has_codegen_attrs() {
         return false;
     }
+
     let codegen_attrs = tcx.codegen_fn_attrs(def_id);
     codegen_attrs.contains_extern_indicator()
         // FIXME(nbdd0121): `#[used]` are marked as reachable here so it's picked up by
diff --git a/compiler/rustc_pattern_analysis/Cargo.toml b/compiler/rustc_pattern_analysis/Cargo.toml
index a59f7bbeb9e..39f660c8771 100644
--- a/compiler/rustc_pattern_analysis/Cargo.toml
+++ b/compiler/rustc_pattern_analysis/Cargo.toml
@@ -19,7 +19,7 @@ rustc_middle = { path = "../rustc_middle", optional = true }
 rustc_session = { path = "../rustc_session", optional = true }
 rustc_span = { path = "../rustc_span", optional = true }
 smallvec = { version = "1.8.1", features = ["union"] }
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
 
 [dev-dependencies]
diff --git a/compiler/rustc_pattern_analysis/src/rustc.rs b/compiler/rustc_pattern_analysis/src/rustc.rs
index 0c1b0d622f2..c9bf4fe4449 100644
--- a/compiler/rustc_pattern_analysis/src/rustc.rs
+++ b/compiler/rustc_pattern_analysis/src/rustc.rs
@@ -8,7 +8,6 @@ use rustc_hir::HirId;
 use rustc_hir::def_id::DefId;
 use rustc_index::{Idx, IndexVec};
 use rustc_middle::middle::stability::EvalResult;
-use rustc_middle::mir::{self, Const};
 use rustc_middle::thir::{self, Pat, PatKind, PatRange, PatRangeBoundary};
 use rustc_middle::ty::layout::IntegerExt;
 use rustc_middle::ty::{
@@ -430,7 +429,7 @@ impl<'p, 'tcx: 'p> RustcPatCtxt<'p, 'tcx> {
         match bdy {
             PatRangeBoundary::NegInfinity => MaybeInfiniteInt::NegInfinity,
             PatRangeBoundary::Finite(value) => {
-                let bits = value.eval_bits(self.tcx, self.typing_env);
+                let bits = value.try_to_scalar_int().unwrap().to_bits_unchecked();
                 match *ty.kind() {
                     ty::Int(ity) => {
                         let size = Integer::from_int_ty(&self.tcx, ity).size().bits();
@@ -520,75 +519,54 @@ impl<'p, 'tcx: 'p> RustcPatCtxt<'p, 'tcx> {
             PatKind::Constant { value } => {
                 match ty.kind() {
                     ty::Bool => {
-                        ctor = match value.try_eval_bool(cx.tcx, cx.typing_env) {
-                            Some(b) => Bool(b),
-                            None => Opaque(OpaqueId::new()),
-                        };
+                        ctor = Bool(value.try_to_bool().unwrap());
                         fields = vec![];
                         arity = 0;
                     }
                     ty::Char | ty::Int(_) | ty::Uint(_) => {
-                        ctor = match value.try_eval_bits(cx.tcx, cx.typing_env) {
-                            Some(bits) => {
-                                let x = match *ty.kind() {
-                                    ty::Int(ity) => {
-                                        let size = Integer::from_int_ty(&cx.tcx, ity).size().bits();
-                                        MaybeInfiniteInt::new_finite_int(bits, size)
-                                    }
-                                    _ => MaybeInfiniteInt::new_finite_uint(bits),
-                                };
-                                IntRange(IntRange::from_singleton(x))
-                            }
-                            None => Opaque(OpaqueId::new()),
+                        ctor = {
+                            let bits = value.valtree.unwrap_leaf().to_bits_unchecked();
+                            let x = match *ty.kind() {
+                                ty::Int(ity) => {
+                                    let size = Integer::from_int_ty(&cx.tcx, ity).size().bits();
+                                    MaybeInfiniteInt::new_finite_int(bits, size)
+                                }
+                                _ => MaybeInfiniteInt::new_finite_uint(bits),
+                            };
+                            IntRange(IntRange::from_singleton(x))
                         };
                         fields = vec![];
                         arity = 0;
                     }
                     ty::Float(ty::FloatTy::F16) => {
-                        ctor = match value.try_eval_bits(cx.tcx, cx.typing_env) {
-                            Some(bits) => {
-                                use rustc_apfloat::Float;
-                                let value = rustc_apfloat::ieee::Half::from_bits(bits);
-                                F16Range(value, value, RangeEnd::Included)
-                            }
-                            None => Opaque(OpaqueId::new()),
-                        };
+                        use rustc_apfloat::Float;
+                        let bits = value.valtree.unwrap_leaf().to_u16();
+                        let value = rustc_apfloat::ieee::Half::from_bits(bits.into());
+                        ctor = F16Range(value, value, RangeEnd::Included);
                         fields = vec![];
                         arity = 0;
                     }
                     ty::Float(ty::FloatTy::F32) => {
-                        ctor = match value.try_eval_bits(cx.tcx, cx.typing_env) {
-                            Some(bits) => {
-                                use rustc_apfloat::Float;
-                                let value = rustc_apfloat::ieee::Single::from_bits(bits);
-                                F32Range(value, value, RangeEnd::Included)
-                            }
-                            None => Opaque(OpaqueId::new()),
-                        };
+                        use rustc_apfloat::Float;
+                        let bits = value.valtree.unwrap_leaf().to_u32();
+                        let value = rustc_apfloat::ieee::Single::from_bits(bits.into());
+                        ctor = F32Range(value, value, RangeEnd::Included);
                         fields = vec![];
                         arity = 0;
                     }
                     ty::Float(ty::FloatTy::F64) => {
-                        ctor = match value.try_eval_bits(cx.tcx, cx.typing_env) {
-                            Some(bits) => {
-                                use rustc_apfloat::Float;
-                                let value = rustc_apfloat::ieee::Double::from_bits(bits);
-                                F64Range(value, value, RangeEnd::Included)
-                            }
-                            None => Opaque(OpaqueId::new()),
-                        };
+                        use rustc_apfloat::Float;
+                        let bits = value.valtree.unwrap_leaf().to_u64();
+                        let value = rustc_apfloat::ieee::Double::from_bits(bits.into());
+                        ctor = F64Range(value, value, RangeEnd::Included);
                         fields = vec![];
                         arity = 0;
                     }
                     ty::Float(ty::FloatTy::F128) => {
-                        ctor = match value.try_eval_bits(cx.tcx, cx.typing_env) {
-                            Some(bits) => {
-                                use rustc_apfloat::Float;
-                                let value = rustc_apfloat::ieee::Quad::from_bits(bits);
-                                F128Range(value, value, RangeEnd::Included)
-                            }
-                            None => Opaque(OpaqueId::new()),
-                        };
+                        use rustc_apfloat::Float;
+                        let bits = value.valtree.unwrap_leaf().to_u128();
+                        let value = rustc_apfloat::ieee::Quad::from_bits(bits);
+                        ctor = F128Range(value, value, RangeEnd::Included);
                         fields = vec![];
                         arity = 0;
                     }
@@ -630,8 +608,12 @@ impl<'p, 'tcx: 'p> RustcPatCtxt<'p, 'tcx> {
                     }
                     ty::Float(fty) => {
                         use rustc_apfloat::Float;
-                        let lo = lo.as_finite().map(|c| c.eval_bits(cx.tcx, cx.typing_env));
-                        let hi = hi.as_finite().map(|c| c.eval_bits(cx.tcx, cx.typing_env));
+                        let lo = lo
+                            .as_finite()
+                            .map(|c| c.try_to_scalar_int().unwrap().to_bits_unchecked());
+                        let hi = hi
+                            .as_finite()
+                            .map(|c| c.try_to_scalar_int().unwrap().to_bits_unchecked());
                         match fty {
                             ty::FloatTy::F16 => {
                                 use rustc_apfloat::ieee::Half;
@@ -739,8 +721,8 @@ impl<'p, 'tcx: 'p> RustcPatCtxt<'p, 'tcx> {
                 };
                 match ScalarInt::try_from_uint(bits, size) {
                     Some(scalar) => {
-                        let value = mir::Const::from_scalar(tcx, scalar.into(), ty.inner());
-                        PatRangeBoundary::Finite(value)
+                        let valtree = ty::ValTree::from_scalar_int(tcx, scalar);
+                        PatRangeBoundary::Finite(valtree)
                     }
                     // The value doesn't fit. Since `x >= 0` and 0 always encodes the minimum value
                     // for a type, the problem isn't that the value is too small. So it must be too
@@ -760,7 +742,7 @@ impl<'p, 'tcx: 'p> RustcPatCtxt<'p, 'tcx> {
             "_".to_string()
         } else if range.is_singleton() {
             let lo = cx.hoist_pat_range_bdy(range.lo, ty);
-            let value = lo.as_finite().unwrap();
+            let value = ty::Value { ty: ty.inner(), valtree: lo.as_finite().unwrap() };
             value.to_string()
         } else {
             // We convert to an inclusive range for diagnostics.
@@ -772,7 +754,9 @@ impl<'p, 'tcx: 'p> RustcPatCtxt<'p, 'tcx> {
                 // fictitious values after `{u,i}size::MAX` (see [`IntRange::split`] for why we do
                 // this). We show this to the user as `usize::MAX..` which is slightly incorrect but
                 // probably clear enough.
-                lo = PatRangeBoundary::Finite(ty.numeric_max_val(cx.tcx).unwrap());
+                let max = ty.numeric_max_val(cx.tcx).unwrap();
+                let max = ty::ValTree::from_scalar_int(cx.tcx, max.try_to_scalar_int().unwrap());
+                lo = PatRangeBoundary::Finite(max);
             }
             let hi = if let Some(hi) = range.hi.minus_one() {
                 hi
@@ -907,7 +891,7 @@ impl<'p, 'tcx: 'p> PatCx for RustcPatCtxt<'p, 'tcx> {
     type Ty = RevealedTy<'tcx>;
     type Error = ErrorGuaranteed;
     type VariantIdx = VariantIdx;
-    type StrLit = Const<'tcx>;
+    type StrLit = ty::Value<'tcx>;
     type ArmData = HirId;
     type PatData = &'p Pat<'tcx>;
 
diff --git a/compiler/rustc_pattern_analysis/src/rustc/print.rs b/compiler/rustc_pattern_analysis/src/rustc/print.rs
index 7649f72f868..cdf62c2553d 100644
--- a/compiler/rustc_pattern_analysis/src/rustc/print.rs
+++ b/compiler/rustc_pattern_analysis/src/rustc/print.rs
@@ -101,23 +101,11 @@ pub(crate) fn write_struct_like<'tcx>(
     let num_fields = variant_and_name.as_ref().map_or(subpatterns.len(), |(v, _)| v.fields.len());
     if num_fields != 0 || variant_and_name.is_none() {
         write!(f, "(")?;
-        for i in 0..num_fields {
-            write!(f, "{}", start_or_comma())?;
-
-            // Common case: the field is where we expect it.
-            if let Some(p) = subpatterns.get(i) {
-                if p.field.index() == i {
-                    write!(f, "{}", p.pattern)?;
-                    continue;
-                }
-            }
-
-            // Otherwise, we have to go looking for it.
-            if let Some(p) = subpatterns.iter().find(|p| p.field.index() == i) {
-                write!(f, "{}", p.pattern)?;
-            } else {
-                write!(f, "_")?;
-            }
+        for FieldPat { pattern, .. } in subpatterns {
+            write!(f, "{}{pattern}", start_or_comma())?;
+        }
+        if matches!(ty.kind(), ty::Tuple(..)) && num_fields == 1 {
+            write!(f, ",")?;
         }
         write!(f, ")")?;
     }
diff --git a/compiler/rustc_privacy/Cargo.toml b/compiler/rustc_privacy/Cargo.toml
index c8bfdb91304..7de58132e13 100644
--- a/compiler/rustc_privacy/Cargo.toml
+++ b/compiler/rustc_privacy/Cargo.toml
@@ -15,5 +15,5 @@ rustc_middle = { path = "../rustc_middle" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_ty_utils = { path = "../rustc_ty_utils" }
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_proc_macro/Cargo.toml b/compiler/rustc_proc_macro/Cargo.toml
index beb95aa3b52..99e7fc7abc6 100644
--- a/compiler/rustc_proc_macro/Cargo.toml
+++ b/compiler/rustc_proc_macro/Cargo.toml
@@ -16,7 +16,7 @@ doctest = false
 
 [dependencies]
 # tidy-alphabetical-start
-rustc-literal-escaper = "0.0.5"
+rustc-literal-escaper.workspace = true
 # tidy-alphabetical-end
 
 [features]
diff --git a/compiler/rustc_public/Cargo.toml b/compiler/rustc_public/Cargo.toml
index 70af30c1a5f..71d339b5792 100644
--- a/compiler/rustc_public/Cargo.toml
+++ b/compiler/rustc_public/Cargo.toml
@@ -14,7 +14,7 @@ rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 scoped-tls = "1.0"
 serde = { version = "1.0.125", features = [ "derive" ] }
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
 
 [features]
diff --git a/compiler/rustc_query_impl/Cargo.toml b/compiler/rustc_query_impl/Cargo.toml
index e5cceacf15d..2005b8b9eca 100644
--- a/compiler/rustc_query_impl/Cargo.toml
+++ b/compiler/rustc_query_impl/Cargo.toml
@@ -15,5 +15,5 @@ rustc_query_system = { path = "../rustc_query_system" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_query_system/Cargo.toml b/compiler/rustc_query_system/Cargo.toml
index 7480ba03474..0df933bc81c 100644
--- a/compiler/rustc_query_system/Cargo.toml
+++ b/compiler/rustc_query_system/Cargo.toml
@@ -21,7 +21,7 @@ rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_thread_pool = { path = "../rustc_thread_pool" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
 
 [dependencies.hashbrown]
diff --git a/compiler/rustc_resolve/Cargo.toml b/compiler/rustc_resolve/Cargo.toml
index eb98a6e85c0..7c5332c1662 100644
--- a/compiler/rustc_resolve/Cargo.toml
+++ b/compiler/rustc_resolve/Cargo.toml
@@ -5,9 +5,9 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-bitflags = "2.4.1"
+bitflags.workspace = true
 indexmap = "2.4.0"
-itertools = "0.12"
+itertools.workspace = true
 pulldown-cmark = { version = "0.11", features = ["html"], default-features = false }
 rustc_arena = { path = "../rustc_arena" }
 rustc_ast = { path = "../rustc_ast" }
@@ -27,6 +27,6 @@ rustc_query_system = { path = "../rustc_query_system" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec = "0.2.12"
-tracing = "0.1"
+thin-vec.workspace = true
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_resolve/messages.ftl b/compiler/rustc_resolve/messages.ftl
index ceef558c0cf..47280a93677 100644
--- a/compiler/rustc_resolve/messages.ftl
+++ b/compiler/rustc_resolve/messages.ftl
@@ -93,6 +93,9 @@ resolve_consider_adding_a_derive =
 resolve_consider_adding_macro_export =
     consider adding a `#[macro_export]` to the macro in the imported module
 
+resolve_consider_marking_as_pub_crate =
+    in case you want to use the macro within this crate only, reduce the visibility to `pub(crate)`
+
 resolve_consider_declaring_with_pub =
     consider declaring type or module `{$ident}` with `pub`
 
@@ -242,11 +245,14 @@ resolve_lowercase_self =
     attempt to use a non-constant value in a constant
     .suggestion = try using `Self`
 
+resolve_macro_cannot_use_as_fn_like =
+    `{$ident}` exists, but has no rules for function-like invocation
+
 resolve_macro_cannot_use_as_attr =
     `{$ident}` exists, but has no `attr` rules
 
 resolve_macro_cannot_use_as_derive =
-     `{$ident}` exists, but a declarative macro cannot be used as a derive macro
+     `{$ident}` exists, but has no `derive` rules
 
 resolve_macro_defined_later =
     a macro with the same name exists, but it appears later
diff --git a/compiler/rustc_resolve/src/build_reduced_graph.rs b/compiler/rustc_resolve/src/build_reduced_graph.rs
index 3fee2ab6afe..f75a625a279 100644
--- a/compiler/rustc_resolve/src/build_reduced_graph.rs
+++ b/compiler/rustc_resolve/src/build_reduced_graph.rs
@@ -11,7 +11,7 @@ use std::sync::Arc;
 use rustc_ast::visit::{self, AssocCtxt, Visitor, WalkItemKind};
 use rustc_ast::{
     self as ast, AssocItem, AssocItemKind, Block, ConstItem, Delegation, Fn, ForeignItem,
-    ForeignItemKind, Item, ItemKind, NodeId, StaticItem, StmtKind, TyAlias,
+    ForeignItemKind, Inline, Item, ItemKind, NodeId, StaticItem, StmtKind, TyAlias,
 };
 use rustc_attr_parsing as attr;
 use rustc_attr_parsing::AttributeParser;
@@ -210,6 +210,17 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         }
     }
 
+    /// Add every proc macro accessible from the current crate to the `macro_map` so diagnostics can
+    /// find them for suggestions.
+    pub(crate) fn register_macros_for_all_crates(&mut self) {
+        if !self.all_crate_macros_already_registered {
+            for def_id in self.cstore().all_proc_macro_def_ids() {
+                self.get_macro_by_def_id(def_id);
+            }
+            self.all_crate_macros_already_registered = true;
+        }
+    }
+
     pub(crate) fn build_reduced_graph(
         &mut self,
         fragment: &AstFragment,
@@ -474,6 +485,7 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
             root_span,
             root_id,
             vis,
+            vis_span: item.vis.span,
         });
 
         self.r.indeterminate_imports.push(import);
@@ -493,9 +505,6 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
                     });
                 }
             }
-            // We don't add prelude imports to the globs since they only affect lexical scopes,
-            // which are not relevant to import resolution.
-            ImportKind::Glob { is_prelude: true, .. } => {}
             ImportKind::Glob { .. } => current_module.globs.borrow_mut().push(import),
             _ => unreachable!(),
         }
@@ -658,13 +667,19 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
                 self.add_import(module_path, kind, use_tree.span, item, root_span, item.id, vis);
             }
             ast::UseTreeKind::Glob => {
-                let kind = ImportKind::Glob {
-                    is_prelude: ast::attr::contains_name(&item.attrs, sym::prelude_import),
-                    max_vis: Cell::new(None),
-                    id,
-                };
-
-                self.add_import(prefix, kind, use_tree.span, item, root_span, item.id, vis);
+                if !ast::attr::contains_name(&item.attrs, sym::prelude_import) {
+                    let kind = ImportKind::Glob { max_vis: Cell::new(None), id };
+                    self.add_import(prefix, kind, use_tree.span, item, root_span, item.id, vis);
+                } else {
+                    // Resolve the prelude import early.
+                    let path_res =
+                        self.r.cm().maybe_resolve_path(&prefix, None, &self.parent_scope, None);
+                    if let PathResult::Module(ModuleOrUniformRoot::Module(module)) = path_res {
+                        self.r.prelude = Some(module);
+                    } else {
+                        self.r.dcx().span_err(use_tree.span, "cannot resolve a prelude import");
+                    }
+                }
             }
             ast::UseTreeKind::Nested { ref items, .. } => {
                 // Ensure there is at most one `self` in the list
@@ -798,7 +813,8 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
             ItemKind::Mod(_, ident, ref mod_kind) => {
                 self.r.define_local(parent, ident, TypeNS, res, vis, sp, expansion);
 
-                if let ast::ModKind::Loaded(_, _, _, Err(_)) = mod_kind {
+                if let ast::ModKind::Loaded(_, Inline::No { had_parse_error: Err(_) }, _) = mod_kind
+                {
                     self.r.mods_with_parse_errors.insert(def_id);
                 }
                 self.parent_scope.module = self.r.new_local_module(
@@ -963,6 +979,7 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
             span: item.span,
             module_path: Vec::new(),
             vis,
+            vis_span: item.vis.span,
         });
         if used {
             self.r.import_use_map.insert(import, Used::Other);
@@ -971,40 +988,35 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
         let imported_binding = self.r.import(binding, import);
         if ident.name != kw::Underscore && parent == self.r.graph_root {
             let norm_ident = Macros20NormalizedIdent::new(ident);
+            // FIXME: this error is technically unnecessary now when extern prelude is split into
+            // two scopes, remove it with lang team approval.
             if let Some(entry) = self.r.extern_prelude.get(&norm_ident)
                 && expansion != LocalExpnId::ROOT
                 && orig_name.is_some()
-                && !entry.is_import()
+                && entry.item_binding.is_none()
             {
                 self.r.dcx().emit_err(
                     errors::MacroExpandedExternCrateCannotShadowExternArguments { span: item.span },
                 );
-                // `return` is intended to discard this binding because it's an
-                // unregistered ambiguity error which would result in a panic
-                // caused by inconsistency `path_res`
-                // more details: https://github.com/rust-lang/rust/pull/111761
-                return;
             }
 
             use indexmap::map::Entry;
             match self.r.extern_prelude.entry(norm_ident) {
                 Entry::Occupied(mut occupied) => {
                     let entry = occupied.get_mut();
-                    if let Some(old_binding) = entry.binding.get()
-                        && old_binding.is_import()
-                    {
+                    if entry.item_binding.is_some() {
                         let msg = format!("extern crate `{ident}` already in extern prelude");
                         self.r.tcx.dcx().span_delayed_bug(item.span, msg);
                     } else {
-                        // Binding from `extern crate` item in source code can replace
-                        // a binding from `--extern` on command line here.
-                        entry.binding.set(Some(imported_binding));
+                        entry.item_binding = Some(imported_binding);
                         entry.introduced_by_item = orig_name.is_some();
                     }
                     entry
                 }
                 Entry::Vacant(vacant) => vacant.insert(ExternPreludeEntry {
-                    binding: Cell::new(Some(imported_binding)),
+                    item_binding: Some(imported_binding),
+                    flag_binding: Cell::new(None),
+                    only_item: true,
                     introduced_by_item: true,
                 }),
             };
@@ -1102,6 +1114,7 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
                 span,
                 module_path: Vec::new(),
                 vis: Visibility::Restricted(CRATE_DEF_ID),
+                vis_span: item.vis.span,
             })
         };
 
@@ -1232,7 +1245,8 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
             ItemKind::Fn(box ast::Fn { ident: fn_ident, .. }) => {
                 match self.proc_macro_stub(item, *fn_ident) {
                     Some((macro_kind, ident, span)) => {
-                        let res = Res::Def(DefKind::Macro(macro_kind), def_id.to_def_id());
+                        let macro_kinds = macro_kind.into();
+                        let res = Res::Def(DefKind::Macro(macro_kinds), def_id.to_def_id());
                         let macro_data = MacroData::new(self.r.dummy_ext(macro_kind));
                         self.r.new_local_macro(def_id, macro_data);
                         self.r.proc_macro_stubs.insert(def_id);
@@ -1271,6 +1285,7 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
                     span,
                     module_path: Vec::new(),
                     vis,
+                    vis_span: item.vis.span,
                 });
                 self.r.import_use_map.insert(import, Used::Other);
                 let import_binding = self.r.import(binding, import);
diff --git a/compiler/rustc_resolve/src/def_collector.rs b/compiler/rustc_resolve/src/def_collector.rs
index 7d51fef28d3..14538df8187 100644
--- a/compiler/rustc_resolve/src/def_collector.rs
+++ b/compiler/rustc_resolve/src/def_collector.rs
@@ -5,6 +5,7 @@ use rustc_ast::*;
 use rustc_attr_parsing::{AttributeParser, Early, OmitDoc, ShouldEmit};
 use rustc_expand::expand::AstFragment;
 use rustc_hir as hir;
+use rustc_hir::Target;
 use rustc_hir::def::{CtorKind, CtorOf, DefKind};
 use rustc_hir::def_id::LocalDefId;
 use rustc_middle::span_bug;
@@ -138,6 +139,7 @@ impl<'a, 'ra, 'tcx> visit::Visitor<'a> for DefCollector<'a, 'ra, 'tcx> {
                     &i.attrs,
                     i.span,
                     i.id,
+                    Target::MacroDef,
                     OmitDoc::Skip,
                     std::convert::identity,
                     |_l| {
@@ -149,9 +151,9 @@ impl<'a, 'ra, 'tcx> visit::Visitor<'a> for DefCollector<'a, 'ra, 'tcx> {
 
                 let macro_data =
                     self.resolver.compile_macro(def, *ident, &attrs, i.span, i.id, edition);
-                let macro_kind = macro_data.ext.macro_kind();
+                let macro_kinds = macro_data.ext.macro_kinds();
                 opt_macro_data = Some(macro_data);
-                DefKind::Macro(macro_kind)
+                DefKind::Macro(macro_kinds)
             }
             ItemKind::GlobalAsm(..) => DefKind::GlobalAsm,
             ItemKind::Use(use_tree) => {
diff --git a/compiler/rustc_resolve/src/diagnostics.rs b/compiler/rustc_resolve/src/diagnostics.rs
index 210ab72678c..337e7d2dd86 100644
--- a/compiler/rustc_resolve/src/diagnostics.rs
+++ b/compiler/rustc_resolve/src/diagnostics.rs
@@ -13,7 +13,7 @@ use rustc_errors::{
 use rustc_feature::BUILTIN_ATTRIBUTES;
 use rustc_hir::attrs::{AttributeKind, CfgEntry, StrippedCfgItem};
 use rustc_hir::def::Namespace::{self, *};
-use rustc_hir::def::{self, CtorKind, CtorOf, DefKind, NonMacroAttrKind, PerNS};
+use rustc_hir::def::{self, CtorKind, CtorOf, DefKind, MacroKinds, NonMacroAttrKind, PerNS};
 use rustc_hir::def_id::{CRATE_DEF_ID, DefId};
 use rustc_hir::{PrimTy, Stability, StabilityLevel, find_attr};
 use rustc_middle::bug;
@@ -1016,17 +1016,15 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         .emit()
     }
 
-    /// Lookup typo candidate in scope for a macro or import.
-    fn early_lookup_typo_candidate(
+    pub(crate) fn add_scope_set_candidates(
         &mut self,
+        suggestions: &mut Vec<TypoSuggestion>,
         scope_set: ScopeSet<'ra>,
-        parent_scope: &ParentScope<'ra>,
-        ident: Ident,
+        ps: &ParentScope<'ra>,
+        ctxt: SyntaxContext,
         filter_fn: &impl Fn(Res) -> bool,
-    ) -> Option<TypoSuggestion> {
-        let mut suggestions = Vec::new();
-        let ctxt = ident.span.ctxt();
-        self.cm().visit_scopes(scope_set, parent_scope, ctxt, |this, scope, use_prelude, _| {
+    ) {
+        self.cm().visit_scopes(scope_set, ps, ctxt, None, |this, scope, use_prelude, _| {
             match scope {
                 Scope::DeriveHelpers(expn_id) => {
                     let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelper);
@@ -1041,28 +1039,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     }
                 }
                 Scope::DeriveHelpersCompat => {
-                    let res = Res::NonMacroAttr(NonMacroAttrKind::DeriveHelperCompat);
-                    if filter_fn(res) {
-                        for derive in parent_scope.derives {
-                            let parent_scope = &ParentScope { derives: &[], ..*parent_scope };
-                            let Ok((Some(ext), _)) = this.reborrow().resolve_macro_path(
-                                derive,
-                                Some(MacroKind::Derive),
-                                parent_scope,
-                                false,
-                                false,
-                                None,
-                                None,
-                            ) else {
-                                continue;
-                            };
-                            suggestions.extend(
-                                ext.helper_attrs
-                                    .iter()
-                                    .map(|name| TypoSuggestion::typo_from_name(*name, res)),
-                            );
-                        }
-                    }
+                    // Never recommend deprecated helper attributes.
                 }
                 Scope::MacroRules(macro_rules_scope) => {
                     if let MacroRulesScope::Binding(macro_rules_binding) = macro_rules_scope.get() {
@@ -1076,7 +1053,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     }
                 }
                 Scope::Module(module, _) => {
-                    this.add_module_candidates(module, &mut suggestions, filter_fn, None);
+                    this.add_module_candidates(module, suggestions, filter_fn, None);
                 }
                 Scope::MacroUsePrelude => {
                     suggestions.extend(this.macro_use_prelude.iter().filter_map(
@@ -1096,12 +1073,14 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         );
                     }
                 }
-                Scope::ExternPrelude => {
+                Scope::ExternPreludeItems => {
+                    // Add idents from both item and flag scopes.
                     suggestions.extend(this.extern_prelude.keys().filter_map(|ident| {
                         let res = Res::Def(DefKind::Mod, CRATE_DEF_ID.to_def_id());
                         filter_fn(res).then_some(TypoSuggestion::typo_from_ident(ident.0, res))
                     }));
                 }
+                Scope::ExternPreludeFlags => {}
                 Scope::ToolPrelude => {
                     let res = Res::NonMacroAttr(NonMacroAttrKind::Tool);
                     suggestions.extend(
@@ -1132,6 +1111,19 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
 
             None::<()>
         });
+    }
+
+    /// Lookup typo candidate in scope for a macro or import.
+    fn early_lookup_typo_candidate(
+        &mut self,
+        scope_set: ScopeSet<'ra>,
+        parent_scope: &ParentScope<'ra>,
+        ident: Ident,
+        filter_fn: &impl Fn(Res) -> bool,
+    ) -> Option<TypoSuggestion> {
+        let mut suggestions = Vec::new();
+        let ctxt = ident.span.ctxt();
+        self.add_scope_set_candidates(&mut suggestions, scope_set, parent_scope, ctxt, filter_fn);
 
         // Make sure error reporting is deterministic.
         suggestions.sort_by(|a, b| a.candidate.as_str().cmp(b.candidate.as_str()));
@@ -1477,34 +1469,12 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         krate: &Crate,
         sugg_span: Option<Span>,
     ) {
-        // Bring imported but unused `derive` macros into `macro_map` so we ensure they can be used
-        // for suggestions.
-        self.cm().visit_scopes(
-            ScopeSet::Macro(MacroKind::Derive),
-            &parent_scope,
-            ident.span.ctxt(),
-            |this, scope, _use_prelude, _ctxt| {
-                let Scope::Module(m, _) = scope else {
-                    return None;
-                };
-                for (_, resolution) in this.resolutions(m).borrow().iter() {
-                    let Some(binding) = resolution.borrow().best_binding() else {
-                        continue;
-                    };
-                    let Res::Def(DefKind::Macro(MacroKind::Derive | MacroKind::Attr), def_id) =
-                        binding.res()
-                    else {
-                        continue;
-                    };
-                    // By doing this all *imported* macros get added to the `macro_map` even if they
-                    // are *unused*, which makes the later suggestions find them and work.
-                    let _ = this.get_macro_by_def_id(def_id);
-                }
-                None::<()>
-            },
-        );
+        // Bring all unused `derive` macros into `macro_map` so we ensure they can be used for
+        // suggestions.
+        self.register_macros_for_all_crates();
 
-        let is_expected = &|res: Res| res.macro_kind() == Some(macro_kind);
+        let is_expected =
+            &|res: Res| res.macro_kinds().is_some_and(|k| k.contains(macro_kind.into()));
         let suggestion = self.early_lookup_typo_candidate(
             ScopeSet::Macro(macro_kind),
             parent_scope,
@@ -1553,11 +1523,11 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         if let Some((def_id, unused_ident)) = unused_macro {
             let scope = self.local_macro_def_scopes[&def_id];
             let parent_nearest = parent_scope.module.nearest_parent_mod();
-            if Some(parent_nearest) == scope.opt_def_id() {
+            let unused_macro_kinds = self.local_macro_map[def_id].ext.macro_kinds();
+            if !unused_macro_kinds.contains(macro_kind.into()) {
                 match macro_kind {
                     MacroKind::Bang => {
-                        err.subdiagnostic(MacroDefinedLater { span: unused_ident.span });
-                        err.subdiagnostic(MacroSuggMovePosition { span: ident.span, ident });
+                        err.subdiagnostic(MacroRulesNot::Func { span: unused_ident.span, ident });
                     }
                     MacroKind::Attr => {
                         err.subdiagnostic(MacroRulesNot::Attr { span: unused_ident.span, ident });
@@ -1566,14 +1536,13 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         err.subdiagnostic(MacroRulesNot::Derive { span: unused_ident.span, ident });
                     }
                 }
-
                 return;
             }
-        }
-
-        if self.macro_names.contains(&ident.normalize_to_macros_2_0()) {
-            err.subdiagnostic(AddedMacroUse);
-            return;
+            if Some(parent_nearest) == scope.opt_def_id() {
+                err.subdiagnostic(MacroDefinedLater { span: unused_ident.span });
+                err.subdiagnostic(MacroSuggMovePosition { span: ident.span, ident });
+                return;
+            }
         }
 
         if ident.name == kw::Default
@@ -1588,7 +1557,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             });
         }
         for ns in [Namespace::MacroNS, Namespace::TypeNS, Namespace::ValueNS] {
-            let Ok(binding) = self.cm().early_resolve_ident_in_lexical_scope(
+            let Ok(binding) = self.cm().resolve_ident_in_scope_set(
                 ident,
                 ScopeSet::All(ns),
                 parent_scope,
@@ -1601,13 +1570,18 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             };
 
             let desc = match binding.res() {
-                Res::Def(DefKind::Macro(MacroKind::Bang), _) => "a function-like macro".to_string(),
-                Res::Def(DefKind::Macro(MacroKind::Attr), _) | Res::NonMacroAttr(..) => {
+                Res::Def(DefKind::Macro(MacroKinds::BANG), _) => {
+                    "a function-like macro".to_string()
+                }
+                Res::Def(DefKind::Macro(MacroKinds::ATTR), _) | Res::NonMacroAttr(..) => {
                     format!("an attribute: `#[{ident}]`")
                 }
-                Res::Def(DefKind::Macro(MacroKind::Derive), _) => {
+                Res::Def(DefKind::Macro(MacroKinds::DERIVE), _) => {
                     format!("a derive macro: `#[derive({ident})]`")
                 }
+                Res::Def(DefKind::Macro(kinds), _) => {
+                    format!("{} {}", kinds.article(), kinds.descr())
+                }
                 Res::ToolMod => {
                     // Don't confuse the user with tool modules.
                     continue;
@@ -1644,6 +1618,11 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             err.subdiagnostic(note);
             return;
         }
+
+        if self.macro_names.contains(&ident.normalize_to_macros_2_0()) {
+            err.subdiagnostic(AddedMacroUse);
+            return;
+        }
     }
 
     /// Given an attribute macro that failed to be resolved, look for `derive` macros that could
@@ -1862,14 +1841,20 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         }
     }
 
-    fn ambiguity_diagnostics(&self, ambiguity_error: &AmbiguityError<'_>) -> AmbiguityErrorDiag {
+    fn ambiguity_diagnostics(&self, ambiguity_error: &AmbiguityError<'ra>) -> AmbiguityErrorDiag {
         let AmbiguityError { kind, ident, b1, b2, misc1, misc2, .. } = *ambiguity_error;
+        let extern_prelude_ambiguity = || {
+            self.extern_prelude.get(&Macros20NormalizedIdent::new(ident)).is_some_and(|entry| {
+                entry.item_binding == Some(b1) && entry.flag_binding.get() == Some(b2)
+            })
+        };
         let (b1, b2, misc1, misc2, swapped) = if b2.span.is_dummy() && !b1.span.is_dummy() {
             // We have to print the span-less alternative first, otherwise formatting looks bad.
             (b2, b1, misc2, misc1, true)
         } else {
             (b1, b2, misc1, misc2, false)
         };
+
         let could_refer_to = |b: NameBinding<'_>, misc: AmbiguityErrorMisc, also: &str| {
             let what = self.binding_description(b, ident, misc == AmbiguityErrorMisc::FromPrelude);
             let note_msg = format!("`{ident}` could{also} refer to {what}");
@@ -1885,7 +1870,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     "consider adding an explicit import of `{ident}` to disambiguate"
                 ))
             }
-            if b.is_extern_crate() && ident.span.at_least_rust_2018() {
+            if b.is_extern_crate() && ident.span.at_least_rust_2018() && !extern_prelude_ambiguity()
+            {
                 help_msgs.push(format!("use `::{ident}` to refer to this {thing} unambiguously"))
             }
             match misc {
@@ -2179,9 +2165,9 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         let ast::ExprKind::Struct(struct_expr) = &expr.kind else { return };
         // We don't have to handle type-relative paths because they're forbidden in ADT
         // expressions, but that would change with `#[feature(more_qualified_paths)]`.
-        let Some(Res::Def(_, def_id)) =
-            self.partial_res_map[&struct_expr.path.segments.iter().last().unwrap().id].full_res()
-        else {
+        let Some(segment) = struct_expr.path.segments.last() else { return };
+        let Some(partial_res) = self.partial_res_map.get(&segment.id) else { return };
+        let Some(Res::Def(_, def_id)) = partial_res.full_res() else {
             return;
         };
         let Some(default_fields) = self.field_defaults(def_id) else { return };
@@ -2385,7 +2371,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     }
                 } else {
                     self.cm()
-                        .early_resolve_ident_in_lexical_scope(
+                        .resolve_ident_in_scope_set(
                             ident,
                             ScopeSet::All(ns_to_try),
                             parent_scope,
@@ -2488,7 +2474,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     },
                 )
             });
-            if let Ok(binding) = self.cm().early_resolve_ident_in_lexical_scope(
+            if let Ok(binding) = self.cm().resolve_ident_in_scope_set(
                 ident,
                 ScopeSet::All(ValueNS),
                 parent_scope,
@@ -2748,9 +2734,12 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
 
         let binding_key = BindingKey::new(ident, MacroNS);
         let binding = self.resolution(crate_module, binding_key)?.binding()?;
-        let Res::Def(DefKind::Macro(MacroKind::Bang), _) = binding.res() else {
+        let Res::Def(DefKind::Macro(kinds), _) = binding.res() else {
             return None;
         };
+        if !kinds.contains(MacroKinds::BANG) {
+            return None;
+        }
         let module_name = crate_module.kind.name().unwrap_or(kw::Crate);
         let import_snippet = match import.kind {
             ImportKind::Single { source, target, .. } if source != target => {
@@ -3421,7 +3410,7 @@ impl<'tcx> visit::Visitor<'tcx> for UsePlacementFinder {
 
     fn visit_item(&mut self, item: &'tcx ast::Item) {
         if self.target_module == item.id {
-            if let ItemKind::Mod(_, _, ModKind::Loaded(items, _inline, mod_spans, _)) = &item.kind {
+            if let ItemKind::Mod(_, _, ModKind::Loaded(items, _inline, mod_spans)) = &item.kind {
                 let inject = mod_spans.inject_use_span;
                 if is_span_suitable_for_use_injection(inject) {
                     self.first_legal_span = Some(inject);
diff --git a/compiler/rustc_resolve/src/errors.rs b/compiler/rustc_resolve/src/errors.rs
index 2747ba135ed..63d6fa23a14 100644
--- a/compiler/rustc_resolve/src/errors.rs
+++ b/compiler/rustc_resolve/src/errors.rs
@@ -672,6 +672,12 @@ pub(crate) struct MacroSuggMovePosition {
 
 #[derive(Subdiagnostic)]
 pub(crate) enum MacroRulesNot {
+    #[label(resolve_macro_cannot_use_as_fn_like)]
+    Func {
+        #[primary_span]
+        span: Span,
+        ident: Ident,
+    },
     #[label(resolve_macro_cannot_use_as_attr)]
     Attr {
         #[primary_span]
@@ -770,6 +776,17 @@ pub(crate) struct ConsiderAddingMacroExport {
 }
 
 #[derive(Subdiagnostic)]
+#[suggestion(
+    resolve_consider_marking_as_pub_crate,
+    code = "pub(crate)",
+    applicability = "maybe-incorrect"
+)]
+pub(crate) struct ConsiderMarkingAsPubCrate {
+    #[primary_span]
+    pub(crate) vis_span: Span,
+}
+
+#[derive(Subdiagnostic)]
 #[note(resolve_consider_marking_as_pub)]
 pub(crate) struct ConsiderMarkingAsPub {
     #[primary_span]
diff --git a/compiler/rustc_resolve/src/ident.rs b/compiler/rustc_resolve/src/ident.rs
index 9efcef695b7..dae42645bec 100644
--- a/compiler/rustc_resolve/src/ident.rs
+++ b/compiler/rustc_resolve/src/ident.rs
@@ -2,7 +2,7 @@ use Determinacy::*;
 use Namespace::*;
 use rustc_ast::{self as ast, NodeId};
 use rustc_errors::ErrorGuaranteed;
-use rustc_hir::def::{DefKind, Namespace, NonMacroAttrKind, PartialRes, PerNS};
+use rustc_hir::def::{DefKind, MacroKinds, Namespace, NonMacroAttrKind, PartialRes, PerNS};
 use rustc_middle::bug;
 use rustc_session::lint::BuiltinLintDiag;
 use rustc_session::lint::builtin::PROC_MACRO_DERIVE_RESOLUTION_FALLBACK;
@@ -19,7 +19,7 @@ use crate::{
     AmbiguityError, AmbiguityErrorMisc, AmbiguityKind, BindingKey, CmResolver, Determinacy,
     Finalize, ImportKind, LexicalScopeBinding, Module, ModuleKind, ModuleOrUniformRoot,
     NameBinding, NameBindingKind, ParentScope, PathResult, PrivacyError, Res, ResolutionError,
-    Resolver, Scope, ScopeSet, Segment, Used, Weak, errors,
+    Resolver, Scope, ScopeSet, Segment, Stage, Used, Weak, errors,
 };
 
 #[derive(Copy, Clone)]
@@ -49,6 +49,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         scope_set: ScopeSet<'ra>,
         parent_scope: &ParentScope<'ra>,
         ctxt: SyntaxContext,
+        derive_fallback_lint_id: Option<NodeId>,
         mut visitor: impl FnMut(
             &mut CmResolver<'r, 'ra, 'tcx>,
             Scope<'ra>,
@@ -99,20 +100,21 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
 
         let rust_2015 = ctxt.edition().is_rust_2015();
         let (ns, macro_kind) = match scope_set {
-            ScopeSet::All(ns)
-            | ScopeSet::ModuleAndExternPrelude(ns, _)
-            | ScopeSet::Late(ns, ..) => (ns, None),
+            ScopeSet::All(ns) | ScopeSet::ModuleAndExternPrelude(ns, _) => (ns, None),
+            ScopeSet::ExternPrelude => (TypeNS, None),
             ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind)),
         };
         let module = match scope_set {
             // Start with the specified module.
-            ScopeSet::Late(_, module, _) | ScopeSet::ModuleAndExternPrelude(_, module) => module,
+            ScopeSet::ModuleAndExternPrelude(_, module) => module,
             // Jump out of trait or enum modules, they do not act as scopes.
             _ => parent_scope.module.nearest_item_scope(),
         };
         let module_and_extern_prelude = matches!(scope_set, ScopeSet::ModuleAndExternPrelude(..));
+        let extern_prelude = matches!(scope_set, ScopeSet::ExternPrelude);
         let mut scope = match ns {
             _ if module_and_extern_prelude => Scope::Module(module, None),
+            _ if extern_prelude => Scope::ExternPreludeItems,
             TypeNS | ValueNS => Scope::Module(module, None),
             MacroNS => Scope::DeriveHelpers(parent_scope.expansion),
         };
@@ -143,7 +145,9 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 Scope::Module(..) => true,
                 Scope::MacroUsePrelude => use_prelude || rust_2015,
                 Scope::BuiltinAttrs => true,
-                Scope::ExternPrelude => use_prelude || module_and_extern_prelude,
+                Scope::ExternPreludeItems | Scope::ExternPreludeFlags => {
+                    use_prelude || module_and_extern_prelude || extern_prelude
+                }
                 Scope::ToolPrelude => use_prelude,
                 Scope::StdLibPrelude => use_prelude || ns == MacroNS,
                 Scope::BuiltinTypes => true,
@@ -182,16 +186,12 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 Scope::Module(..) if module_and_extern_prelude => match ns {
                     TypeNS => {
                         ctxt.adjust(ExpnId::root());
-                        Scope::ExternPrelude
+                        Scope::ExternPreludeItems
                     }
                     ValueNS | MacroNS => break,
                 },
                 Scope::Module(module, prev_lint_id) => {
                     use_prelude = !module.no_implicit_prelude;
-                    let derive_fallback_lint_id = match scope_set {
-                        ScopeSet::Late(.., lint_id) => lint_id,
-                        _ => None,
-                    };
                     match self.hygienic_lexical_parent(module, &mut ctxt, derive_fallback_lint_id) {
                         Some((parent_module, lint_id)) => {
                             Scope::Module(parent_module, lint_id.or(prev_lint_id))
@@ -199,7 +199,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         None => {
                             ctxt.adjust(ExpnId::root());
                             match ns {
-                                TypeNS => Scope::ExternPrelude,
+                                TypeNS => Scope::ExternPreludeItems,
                                 ValueNS => Scope::StdLibPrelude,
                                 MacroNS => Scope::MacroUsePrelude,
                             }
@@ -208,8 +208,9 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 }
                 Scope::MacroUsePrelude => Scope::StdLibPrelude,
                 Scope::BuiltinAttrs => break, // nowhere else to search
-                Scope::ExternPrelude if module_and_extern_prelude => break,
-                Scope::ExternPrelude => Scope::ToolPrelude,
+                Scope::ExternPreludeItems => Scope::ExternPreludeFlags,
+                Scope::ExternPreludeFlags if module_and_extern_prelude || extern_prelude => break,
+                Scope::ExternPreludeFlags => Scope::ToolPrelude,
                 Scope::ToolPrelude => Scope::StdLibPrelude,
                 Scope::StdLibPrelude => match ns {
                     TypeNS => Scope::BuiltinTypes,
@@ -259,7 +260,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         {
             let ext = &self.get_macro_by_def_id(def_id).ext;
             if ext.builtin_name.is_none()
-                && ext.macro_kind() == MacroKind::Derive
+                && ext.macro_kinds() == MacroKinds::DERIVE
                 && parent.expansion.outer_expn_is_descendant_of(*ctxt)
             {
                 return Some((parent, derive_fallback_lint_id));
@@ -312,7 +313,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         let normalized_ident = Ident { span: normalized_span, ..ident };
 
         // Walk backwards up the ribs in scope.
-        let mut module = self.graph_root;
         for (i, rib) in ribs.iter().enumerate().rev() {
             debug!("walk rib\n{:?}", rib.bindings);
             // Use the rib kind to determine whether we are resolving parameters
@@ -328,60 +328,54 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     *original_rib_ident_def,
                     ribs,
                 )));
+            } else if let RibKind::Block(Some(module)) = rib.kind
+                && let Ok(binding) = self.cm().resolve_ident_in_module_unadjusted(
+                    ModuleOrUniformRoot::Module(module),
+                    ident,
+                    ns,
+                    parent_scope,
+                    Shadowing::Unrestricted,
+                    finalize.map(|finalize| Finalize { used: Used::Scope, ..finalize }),
+                    ignore_binding,
+                    None,
+                )
+            {
+                // The ident resolves to an item in a block.
+                return Some(LexicalScopeBinding::Item(binding));
+            } else if let RibKind::Module(module) = rib.kind {
+                // Encountered a module item, abandon ribs and look into that module and preludes.
+                let parent_scope = &ParentScope { module, ..*parent_scope };
+                let finalize = finalize.map(|f| Finalize { stage: Stage::Late, ..f });
+                return self
+                    .cm()
+                    .resolve_ident_in_scope_set(
+                        orig_ident,
+                        ScopeSet::All(ns),
+                        parent_scope,
+                        finalize,
+                        finalize.is_some(),
+                        ignore_binding,
+                        None,
+                    )
+                    .ok()
+                    .map(LexicalScopeBinding::Item);
             }
 
-            module = match rib.kind {
-                RibKind::Module(module) => module,
-                RibKind::MacroDefinition(def) if def == self.macro_def(ident.span.ctxt()) => {
-                    // If an invocation of this macro created `ident`, give up on `ident`
-                    // and switch to `ident`'s source from the macro definition.
-                    ident.span.remove_mark();
-                    continue;
-                }
-                _ => continue,
-            };
-
-            match module.kind {
-                ModuleKind::Block => {} // We can see through blocks
-                _ => break,
-            }
-
-            let item = self.cm().resolve_ident_in_module_unadjusted(
-                ModuleOrUniformRoot::Module(module),
-                ident,
-                ns,
-                parent_scope,
-                Shadowing::Unrestricted,
-                finalize.map(|finalize| Finalize { used: Used::Scope, ..finalize }),
-                ignore_binding,
-                None,
-            );
-            if let Ok(binding) = item {
-                // The ident resolves to an item.
-                return Some(LexicalScopeBinding::Item(binding));
+            if let RibKind::MacroDefinition(def) = rib.kind
+                && def == self.macro_def(ident.span.ctxt())
+            {
+                // If an invocation of this macro created `ident`, give up on `ident`
+                // and switch to `ident`'s source from the macro definition.
+                ident.span.remove_mark();
             }
         }
-        self.cm()
-            .early_resolve_ident_in_lexical_scope(
-                orig_ident,
-                ScopeSet::Late(ns, module, finalize.map(|finalize| finalize.node_id)),
-                parent_scope,
-                finalize,
-                finalize.is_some(),
-                ignore_binding,
-                None,
-            )
-            .ok()
-            .map(LexicalScopeBinding::Item)
+
+        unreachable!()
     }
 
-    /// Resolve an identifier in lexical scope.
-    /// This is a variation of `fn resolve_ident_in_lexical_scope` that can be run during
-    /// expansion and import resolution (perhaps they can be merged in the future).
-    /// The function is used for resolving initial segments of macro paths (e.g., `foo` in
-    /// `foo::bar!();` or `foo!();`) and also for import paths on 2018 edition.
+    /// Resolve an identifier in the specified set of scopes.
     #[instrument(level = "debug", skip(self))]
-    pub(crate) fn early_resolve_ident_in_lexical_scope<'r>(
+    pub(crate) fn resolve_ident_in_scope_set<'r>(
         self: CmResolver<'r, 'ra, 'tcx>,
         orig_ident: Ident,
         scope_set: ScopeSet<'ra>,
@@ -410,9 +404,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         }
 
         let (ns, macro_kind) = match scope_set {
-            ScopeSet::All(ns)
-            | ScopeSet::ModuleAndExternPrelude(ns, _)
-            | ScopeSet::Late(ns, ..) => (ns, None),
+            ScopeSet::All(ns) | ScopeSet::ModuleAndExternPrelude(ns, _) => (ns, None),
+            ScopeSet::ExternPrelude => (TypeNS, None),
             ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind)),
         };
 
@@ -429,12 +422,21 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         // to detect potential ambiguities.
         let mut innermost_result: Option<(NameBinding<'_>, Flags)> = None;
         let mut determinacy = Determinacy::Determined;
+        // Shadowed bindings don't need to be marked as used or non-speculatively loaded.
+        macro finalize_scope() {
+            if innermost_result.is_none() { finalize } else { None }
+        }
 
         // Go through all the scopes and try to resolve the name.
+        let derive_fallback_lint_id = match finalize {
+            Some(Finalize { node_id, stage: Stage::Late, .. }) => Some(node_id),
+            _ => None,
+        };
         let break_result = self.visit_scopes(
             scope_set,
             parent_scope,
             orig_ident.span.ctxt(),
+            derive_fallback_lint_id,
             |this, scope, use_prelude, ctxt| {
                 let ident = Ident::new(orig_ident.name, orig_ident.span.with_ctxt(ctxt));
                 let result = match scope {
@@ -448,17 +450,12 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         }
                     }
                     Scope::DeriveHelpersCompat => {
-                        // FIXME: Try running this logic earlier, to allocate name bindings for
-                        // legacy derive helpers when creating an attribute invocation with
-                        // following derives. Legacy derive helpers are not common, so it shouldn't
-                        // affect performance. It should also allow to remove the `derives`
-                        // component from `ParentScope`.
                         let mut result = Err(Determinacy::Determined);
                         for derive in parent_scope.derives {
                             let parent_scope = &ParentScope { derives: &[], ..*parent_scope };
                             match this.reborrow().resolve_macro_path(
                                 derive,
-                                Some(MacroKind::Derive),
+                                MacroKind::Derive,
                                 parent_scope,
                                 true,
                                 force,
@@ -494,7 +491,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         _ => Err(Determinacy::Determined),
                     },
                     Scope::Module(module, derive_fallback_lint_id) => {
-                        let (adjusted_parent_scope, finalize) =
+                        // FIXME: use `finalize_scope` here.
+                        let (adjusted_parent_scope, adjusted_finalize) =
                             if matches!(scope_set, ScopeSet::ModuleAndExternPrelude(..)) {
                                 (parent_scope, finalize)
                             } else {
@@ -508,12 +506,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                             ident,
                             ns,
                             adjusted_parent_scope,
-                            if matches!(scope_set, ScopeSet::Late(..)) {
-                                Shadowing::Unrestricted
-                            } else {
-                                Shadowing::Restricted
-                            },
-                            finalize,
+                            Shadowing::Restricted,
+                            adjusted_finalize,
                             ignore_binding,
                             ignore_import,
                         );
@@ -526,7 +520,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                                         orig_ident.span,
                                         BuiltinLintDiag::ProcMacroDeriveResolutionFallback {
                                             span: orig_ident.span,
-                                            ns,
+                                            ns_descr: ns.descr(),
                                             ident,
                                         },
                                     );
@@ -561,14 +555,21 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         Some(binding) => Ok((*binding, Flags::empty())),
                         None => Err(Determinacy::Determined),
                     },
-                    Scope::ExternPrelude => {
-                        match this.reborrow().extern_prelude_get(ident, finalize.is_some()) {
+                    Scope::ExternPreludeItems => {
+                        // FIXME: use `finalize_scope` here.
+                        match this.reborrow().extern_prelude_get_item(ident, finalize.is_some()) {
                             Some(binding) => Ok((binding, Flags::empty())),
                             None => Err(Determinacy::determined(
                                 this.graph_root.unexpanded_invocations.borrow().is_empty(),
                             )),
                         }
                     }
+                    Scope::ExternPreludeFlags => {
+                        match this.extern_prelude_get_flag(ident, finalize_scope!().is_some()) {
+                            Some(binding) => Ok((binding, Flags::empty())),
+                            None => Err(Determinacy::Determined),
+                        }
+                    }
                     Scope::ToolPrelude => match this.registered_tool_bindings.get(&ident) {
                         Some(binding) => Ok((*binding, Flags::empty())),
                         None => Err(Determinacy::Determined),
@@ -599,8 +600,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                             if matches!(ident.name, sym::f16)
                                 && !this.tcx.features().f16()
                                 && !ident.span.allows_unstable(sym::f16)
-                                && finalize.is_some()
-                                && innermost_result.is_none()
+                                && finalize_scope!().is_some()
                             {
                                 feature_err(
                                     this.tcx.sess,
@@ -613,8 +613,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                             if matches!(ident.name, sym::f128)
                                 && !this.tcx.features().f128()
                                 && !ident.span.allows_unstable(sym::f128)
-                                && finalize.is_some()
-                                && innermost_result.is_none()
+                                && finalize_scope!().is_some()
                             {
                                 feature_err(
                                     this.tcx.sess,
@@ -632,21 +631,15 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
 
                 match result {
                     Ok((binding, flags)) => {
-                        let binding_macro_kind = binding.macro_kind();
-                        // If we're looking for an attribute, that might be supported by a
-                        // `macro_rules!` macro.
-                        // FIXME: Replace this with tracking multiple macro kinds for one Def.
-                        if !(sub_namespace_match(binding_macro_kind, macro_kind)
-                            || (binding_macro_kind == Some(MacroKind::Bang)
-                                && macro_kind == Some(MacroKind::Attr)
-                                && this
-                                    .get_macro(binding.res())
-                                    .is_some_and(|macro_data| macro_data.attr_ext.is_some())))
-                        {
+                        if !sub_namespace_match(binding.macro_kinds(), macro_kind) {
                             return None;
                         }
 
-                        if finalize.is_none() || matches!(scope_set, ScopeSet::Late(..)) {
+                        // Below we report various ambiguity errors.
+                        // We do not need to report them if we are either in speculative resolution,
+                        // or in late resolution when everything is already imported and expanded
+                        // and no ambiguities exist.
+                        if matches!(finalize, None | Some(Finalize { stage: Stage::Late, .. })) {
                             return Some(Ok(binding));
                         }
 
@@ -814,7 +807,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             ModuleOrUniformRoot::Module(module) => module,
             ModuleOrUniformRoot::ModuleAndExternPrelude(module) => {
                 assert_eq!(shadowing, Shadowing::Unrestricted);
-                let binding = self.early_resolve_ident_in_lexical_scope(
+                let binding = self.resolve_ident_in_scope_set(
                     ident,
                     ScopeSet::ModuleAndExternPrelude(ns, module),
                     parent_scope,
@@ -829,15 +822,17 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 assert_eq!(shadowing, Shadowing::Unrestricted);
                 return if ns != TypeNS {
                     Err((Determined, Weak::No))
-                } else if let Some(binding) =
-                    self.reborrow().extern_prelude_get(ident, finalize.is_some())
-                {
-                    Ok(binding)
-                } else if !self.graph_root.unexpanded_invocations.borrow().is_empty() {
-                    // Macro-expanded `extern crate` items can add names to extern prelude.
-                    Err((Undetermined, Weak::No))
                 } else {
-                    Err((Determined, Weak::No))
+                    let binding = self.resolve_ident_in_scope_set(
+                        ident,
+                        ScopeSet::ExternPrelude,
+                        parent_scope,
+                        finalize,
+                        finalize.is_some(),
+                        ignore_binding,
+                        ignore_import,
+                    );
+                    return binding.map_err(|determinacy| (determinacy, Weak::No));
                 };
             }
             ModuleOrUniformRoot::CurrentScope => {
@@ -853,7 +848,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     }
                 }
 
-                let binding = self.early_resolve_ident_in_lexical_scope(
+                let binding = self.resolve_ident_in_scope_set(
                     ident,
                     ScopeSet::All(ns),
                     parent_scope,
@@ -946,7 +941,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         // Now we are in situation when new item/import can appear only from a glob or a macro
         // expansion. With restricted shadowing names from globs and macro expansions cannot
         // shadow names from outer scopes, so we can freely fallback from module search to search
-        // in outer scopes. For `early_resolve_ident_in_lexical_scope` to continue search in outer
+        // in outer scopes. For `resolve_ident_in_scope_set` to continue search in outer
         // scopes we return `Undetermined` with `Weak::Yes`.
 
         // Check if one of unexpanded macros can still define the name,
@@ -1041,6 +1036,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         // Forbid expanded shadowing to avoid time travel.
         if let Some(shadowed_glob) = shadowed_glob
             && shadowing == Shadowing::Restricted
+            && finalize.stage == Stage::Early
             && binding.expansion != LocalExpnId::ROOT
             && binding.res() != shadowed_glob.res()
         {
@@ -1167,6 +1163,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 for rib in ribs {
                     match rib.kind {
                         RibKind::Normal
+                        | RibKind::Block(..)
                         | RibKind::FnOrCoroutine
                         | RibKind::Module(..)
                         | RibKind::MacroDefinition(..)
@@ -1259,6 +1256,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 for rib in ribs {
                     let (has_generic_params, def_kind) = match rib.kind {
                         RibKind::Normal
+                        | RibKind::Block(..)
                         | RibKind::FnOrCoroutine
                         | RibKind::Module(..)
                         | RibKind::MacroDefinition(..)
@@ -1352,6 +1350,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 for rib in ribs {
                     let (has_generic_params, def_kind) = match rib.kind {
                         RibKind::Normal
+                        | RibKind::Block(..)
                         | RibKind::FnOrCoroutine
                         | RibKind::Module(..)
                         | RibKind::MacroDefinition(..)
@@ -1633,7 +1632,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     _ => Err(Determinacy::determined(finalize.is_some())),
                 }
             } else {
-                self.reborrow().early_resolve_ident_in_lexical_scope(
+                self.reborrow().resolve_ident_in_scope_set(
                     ident,
                     ScopeSet::All(ns),
                     parent_scope,
diff --git a/compiler/rustc_resolve/src/imports.rs b/compiler/rustc_resolve/src/imports.rs
index 403d440bee7..d7fc028287f 100644
--- a/compiler/rustc_resolve/src/imports.rs
+++ b/compiler/rustc_resolve/src/imports.rs
@@ -30,7 +30,7 @@ use crate::diagnostics::{DiagMode, Suggestion, import_candidates};
 use crate::errors::{
     CannotBeReexportedCratePublic, CannotBeReexportedCratePublicNS, CannotBeReexportedPrivate,
     CannotBeReexportedPrivateNS, CannotDetermineImportResolution, CannotGlobImportAllCrates,
-    ConsiderAddingMacroExport, ConsiderMarkingAsPub,
+    ConsiderAddingMacroExport, ConsiderMarkingAsPub, ConsiderMarkingAsPubCrate,
 };
 use crate::{
     AmbiguityError, AmbiguityKind, BindingKey, CmResolver, Determinacy, Finalize, ImportSuggestion,
@@ -87,7 +87,6 @@ pub(crate) enum ImportKind<'ra> {
         id: NodeId,
     },
     Glob {
-        is_prelude: bool,
         // The visibility of the greatest re-export.
         // n.b. `max_vis` is only used in `finalize_import` to check for re-export errors.
         max_vis: Cell<Option<Visibility>>,
@@ -125,12 +124,9 @@ impl<'ra> std::fmt::Debug for ImportKind<'ra> {
                 .field("nested", nested)
                 .field("id", id)
                 .finish(),
-            Glob { is_prelude, max_vis, id } => f
-                .debug_struct("Glob")
-                .field("is_prelude", is_prelude)
-                .field("max_vis", max_vis)
-                .field("id", id)
-                .finish(),
+            Glob { max_vis, id } => {
+                f.debug_struct("Glob").field("max_vis", max_vis).field("id", id).finish()
+            }
             ExternCrate { source, target, id } => f
                 .debug_struct("ExternCrate")
                 .field("source", source)
@@ -188,6 +184,9 @@ pub(crate) struct ImportData<'ra> {
     /// |`use foo`        | `ModuleOrUniformRoot::CurrentScope`           | - |
     pub imported_module: Cell<Option<ModuleOrUniformRoot<'ra>>>,
     pub vis: Visibility,
+
+    /// Span of the visibility.
+    pub vis_span: Span,
 }
 
 /// All imports are unique and allocated on a same arena,
@@ -870,7 +869,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             }
             ImportKind::Glob { .. } => {
                 // FIXME: Use mutable resolver directly as a hack, this should be an output of
-                // specualtive resolution.
+                // speculative resolution.
                 self.get_mut_unchecked().resolve_glob_import(import);
                 return 0;
             }
@@ -907,7 +906,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         // We need the `target`, `source` can be extracted.
                         let imported_binding = this.import(binding, import);
                         // FIXME: Use mutable resolver directly as a hack, this should be an output of
-                        // specualtive resolution.
+                        // speculative resolution.
                         this.get_mut_unchecked().define_binding_local(
                             parent,
                             target,
@@ -921,7 +920,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         if target.name != kw::Underscore {
                             let key = BindingKey::new(target, ns);
                             // FIXME: Use mutable resolver directly as a hack, this should be an output of
-                            // specualtive resolution.
+                            // speculative resolution.
                             this.get_mut_unchecked().update_local_resolution(
                                 parent,
                                 key,
@@ -1073,7 +1072,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             ImportKind::Single { source, target, ref bindings, type_ns_only, id, .. } => {
                 (source, target, bindings, type_ns_only, id)
             }
-            ImportKind::Glob { is_prelude, ref max_vis, id } => {
+            ImportKind::Glob { ref max_vis, id } => {
                 if import.module_path.len() <= 1 {
                     // HACK(eddyb) `lint_if_path_starts_with_module` needs at least
                     // 2 segments, so the `resolve_path` above won't trigger it.
@@ -1096,8 +1095,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         module: None,
                     });
                 }
-                if !is_prelude
-                    && let Some(max_vis) = max_vis.get()
+                if let Some(max_vis) = max_vis.get()
                     && !max_vis.is_at_least(import.vis, self.tcx)
                 {
                     let def_id = self.local_def_id(id);
@@ -1373,6 +1371,9 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                             err.subdiagnostic( ConsiderAddingMacroExport {
                                 span: binding.span,
                             });
+                            err.subdiagnostic( ConsiderMarkingAsPubCrate {
+                                vis_span: import.vis_span,
+                            });
                         }
                         _ => {
                             err.subdiagnostic( ConsiderMarkingAsPub {
@@ -1445,7 +1446,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     return;
                 }
 
-                match this.cm().early_resolve_ident_in_lexical_scope(
+                match this.cm().resolve_ident_in_scope_set(
                     target,
                     ScopeSet::All(ns),
                     &import.parent_scope,
@@ -1485,7 +1486,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
 
     fn resolve_glob_import(&mut self, import: Import<'ra>) {
         // This function is only called for glob imports.
-        let ImportKind::Glob { id, is_prelude, .. } = import.kind else { unreachable!() };
+        let ImportKind::Glob { id, .. } = import.kind else { unreachable!() };
 
         let ModuleOrUniformRoot::Module(module) = import.imported_module.get().unwrap() else {
             self.dcx().emit_err(CannotGlobImportAllCrates { span: import.span });
@@ -1504,9 +1505,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
 
         if module == import.parent_scope.module {
             return;
-        } else if is_prelude {
-            self.prelude = Some(module);
-            return;
         }
 
         // Add to module's glob_importers
diff --git a/compiler/rustc_resolve/src/late.rs b/compiler/rustc_resolve/src/late.rs
index e52cbeb733a..d4f7fb276a9 100644
--- a/compiler/rustc_resolve/src/late.rs
+++ b/compiler/rustc_resolve/src/late.rs
@@ -192,6 +192,13 @@ pub(crate) enum RibKind<'ra> {
     /// No restriction needs to be applied.
     Normal,
 
+    /// We passed through an `ast::Block`.
+    /// Behaves like `Normal`, but also partially like `Module` if the block contains items.
+    /// `Block(None)` must be always processed in the same way as `Block(Some(module))`
+    /// with empty `module`. The module can be `None` only because creation of some definitely
+    /// empty modules is skipped as an optimization.
+    Block(Option<Module<'ra>>),
+
     /// We passed through an impl or trait and are now in one of its
     /// methods or associated types. Allow references to ty params that impl or trait
     /// binds. Disallow any other upvars (including other ty params that are
@@ -210,7 +217,7 @@ pub(crate) enum RibKind<'ra> {
     /// All other constants aren't allowed to use generic params at all.
     ConstantItem(ConstantHasGenerics, Option<(Ident, ConstantItemKind)>),
 
-    /// We passed through a module.
+    /// We passed through a module item.
     Module(Module<'ra>),
 
     /// We passed through a `macro_rules!` statement
@@ -242,6 +249,7 @@ impl RibKind<'_> {
     pub(crate) fn contains_params(&self) -> bool {
         match self {
             RibKind::Normal
+            | RibKind::Block(..)
             | RibKind::FnOrCoroutine
             | RibKind::ConstantItem(..)
             | RibKind::Module(_)
@@ -258,15 +266,8 @@ impl RibKind<'_> {
     fn is_label_barrier(self) -> bool {
         match self {
             RibKind::Normal | RibKind::MacroDefinition(..) => false,
-
-            RibKind::AssocItem
-            | RibKind::FnOrCoroutine
-            | RibKind::Item(..)
-            | RibKind::ConstantItem(..)
-            | RibKind::Module(..)
-            | RibKind::ForwardGenericParamBan(_)
-            | RibKind::ConstParamTy
-            | RibKind::InlineAsmSym => true,
+            RibKind::FnOrCoroutine | RibKind::ConstantItem(..) => true,
+            kind => bug!("unexpected rib kind: {kind:?}"),
         }
     }
 }
@@ -1527,19 +1528,6 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
         ret
     }
 
-    fn with_mod_rib<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
-        let module = self.r.expect_module(self.r.local_def_id(id).to_def_id());
-        // Move down in the graph.
-        let orig_module = replace(&mut self.parent_scope.module, module);
-        self.with_rib(ValueNS, RibKind::Module(module), |this| {
-            this.with_rib(TypeNS, RibKind::Module(module), |this| {
-                let ret = f(this);
-                this.parent_scope.module = orig_module;
-                ret
-            })
-        })
-    }
-
     fn visit_generic_params(&mut self, params: &'ast [GenericParam], add_self_upper: bool) {
         // For type parameter defaults, we have to ban access
         // to following type parameters, as the GenericArgs can only
@@ -2677,20 +2665,25 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
             }
 
             ItemKind::Mod(..) => {
-                self.with_mod_rib(item.id, |this| {
-                    if mod_inner_docs {
-                        this.resolve_doc_links(&item.attrs, MaybeExported::Ok(item.id));
-                    }
-                    let old_macro_rules = this.parent_scope.macro_rules;
-                    visit::walk_item(this, item);
-                    // Maintain macro_rules scopes in the same way as during early resolution
-                    // for diagnostics and doc links.
-                    if item.attrs.iter().all(|attr| {
-                        !attr.has_name(sym::macro_use) && !attr.has_name(sym::macro_escape)
-                    }) {
-                        this.parent_scope.macro_rules = old_macro_rules;
-                    }
+                let module = self.r.expect_module(self.r.local_def_id(item.id).to_def_id());
+                let orig_module = replace(&mut self.parent_scope.module, module);
+                self.with_rib(ValueNS, RibKind::Module(module), |this| {
+                    this.with_rib(TypeNS, RibKind::Module(module), |this| {
+                        if mod_inner_docs {
+                            this.resolve_doc_links(&item.attrs, MaybeExported::Ok(item.id));
+                        }
+                        let old_macro_rules = this.parent_scope.macro_rules;
+                        visit::walk_item(this, item);
+                        // Maintain macro_rules scopes in the same way as during early resolution
+                        // for diagnostics and doc links.
+                        if item.attrs.iter().all(|attr| {
+                            !attr.has_name(sym::macro_use) && !attr.has_name(sym::macro_escape)
+                        }) {
+                            this.parent_scope.macro_rules = old_macro_rules;
+                        }
+                    })
                 });
+                self.parent_scope.module = orig_module;
             }
 
             ItemKind::Static(box ast::StaticItem {
@@ -2821,9 +2814,9 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
             // We also can't shadow bindings from associated parent items.
             for ns in [ValueNS, TypeNS] {
                 for parent_rib in self.ribs[ns].iter().rev() {
-                    // Break at mod level, to account for nested items which are
+                    // Break at module or block level, to account for nested items which are
                     // allowed to shadow generic param names.
-                    if matches!(parent_rib.kind, RibKind::Module(..)) {
+                    if matches!(parent_rib.kind, RibKind::Module(..) | RibKind::Block(..)) {
                         break;
                     }
 
@@ -4277,7 +4270,7 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
                         if path.len() == 2
                             && let [segment] = prefix_path
                         {
-                            // Delay to check whether methond name is an associated function or not
+                            // Delay to check whether method name is an associated function or not
                             // ```
                             // let foo = Foo {};
                             // foo::bar(); // possibly suggest to foo.bar();
@@ -4315,7 +4308,6 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
             qself,
             path,
             ns,
-            path_span,
             source.defer_to_typeck(),
             finalize,
             source,
@@ -4438,7 +4430,6 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
         qself: &Option<Box<QSelf>>,
         path: &[Segment],
         primary_ns: Namespace,
-        span: Span,
         defer_to_typeck: bool,
         finalize: Finalize,
         source: PathSource<'_, 'ast, 'ra>,
@@ -4463,21 +4454,11 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
         }
 
         assert!(primary_ns != MacroNS);
-
-        if qself.is_none() {
-            let path_seg = |seg: &Segment| PathSegment::from_ident(seg.ident);
-            let path = Path { segments: path.iter().map(path_seg).collect(), span, tokens: None };
-            if let Ok((_, res)) = self.r.cm().resolve_macro_path(
-                &path,
-                None,
-                &self.parent_scope,
-                false,
-                false,
-                None,
-                None,
-            ) {
-                return Ok(Some(PartialRes::new(res)));
-            }
+        if qself.is_none()
+            && let PathResult::NonModule(res) =
+                self.r.cm().maybe_resolve_path(path, Some(MacroNS), &self.parent_scope, None)
+        {
+            return Ok(Some(res));
         }
 
         Ok(fin_res)
@@ -4664,16 +4645,16 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
         debug!("(resolving block) entering block");
         // Move down in the graph, if there's an anonymous module rooted here.
         let orig_module = self.parent_scope.module;
-        let anonymous_module = self.r.block_map.get(&block.id).cloned(); // clones a reference
+        let anonymous_module = self.r.block_map.get(&block.id).copied();
 
         let mut num_macro_definition_ribs = 0;
         if let Some(anonymous_module) = anonymous_module {
             debug!("(resolving block) found anonymous module, moving down");
-            self.ribs[ValueNS].push(Rib::new(RibKind::Module(anonymous_module)));
-            self.ribs[TypeNS].push(Rib::new(RibKind::Module(anonymous_module)));
+            self.ribs[ValueNS].push(Rib::new(RibKind::Block(Some(anonymous_module))));
+            self.ribs[TypeNS].push(Rib::new(RibKind::Block(Some(anonymous_module))));
             self.parent_scope.module = anonymous_module;
         } else {
-            self.ribs[ValueNS].push(Rib::new(RibKind::Normal));
+            self.ribs[ValueNS].push(Rib::new(RibKind::Block(None)));
         }
 
         // Descend into the block.
@@ -5035,7 +5016,7 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
             }
             ResolveDocLinks::Exported
                 if !maybe_exported.eval(self.r)
-                    && !rustdoc::has_primitive_or_keyword_docs(attrs) =>
+                    && !rustdoc::has_primitive_or_keyword_or_attribute_docs(attrs) =>
             {
                 return;
             }
diff --git a/compiler/rustc_resolve/src/late/diagnostics.rs b/compiler/rustc_resolve/src/late/diagnostics.rs
index aca251da71d..80b2095d8cc 100644
--- a/compiler/rustc_resolve/src/late/diagnostics.rs
+++ b/compiler/rustc_resolve/src/late/diagnostics.rs
@@ -19,14 +19,13 @@ use rustc_errors::{
 };
 use rustc_hir as hir;
 use rustc_hir::def::Namespace::{self, *};
-use rustc_hir::def::{self, CtorKind, CtorOf, DefKind};
+use rustc_hir::def::{self, CtorKind, CtorOf, DefKind, MacroKinds};
 use rustc_hir::def_id::{CRATE_DEF_ID, DefId};
 use rustc_hir::{MissingLifetimeKind, PrimTy};
 use rustc_middle::ty;
 use rustc_session::{Session, lint};
 use rustc_span::edit_distance::{edit_distance, find_best_match_for_name};
 use rustc_span::edition::Edition;
-use rustc_span::hygiene::MacroKind;
 use rustc_span::{DUMMY_SP, Ident, Span, Symbol, kw, sym};
 use thin_vec::ThinVec;
 use tracing::debug;
@@ -39,8 +38,8 @@ use crate::late::{
 };
 use crate::ty::fast_reject::SimplifiedType;
 use crate::{
-    Module, ModuleKind, ModuleOrUniformRoot, PathResult, PathSource, Resolver, Segment, errors,
-    path_names_to_string,
+    Module, ModuleKind, ModuleOrUniformRoot, ParentScope, PathResult, PathSource, Resolver,
+    ScopeSet, Segment, errors, path_names_to_string,
 };
 
 type Res = def::Res<ast::NodeId>;
@@ -850,9 +849,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
         }
 
         // Try to find in last block rib
-        if let Some(rib) = &self.last_block_rib
-            && let RibKind::Normal = rib.kind
-        {
+        if let Some(rib) = &self.last_block_rib {
             for (ident, &res) in &rib.bindings {
                 if let Res::Local(_) = res
                     && path.len() == 1
@@ -901,7 +898,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
         if path.len() == 1 {
             for rib in self.ribs[ns].iter().rev() {
                 let item = path[0].ident;
-                if let RibKind::Module(module) = rib.kind
+                if let RibKind::Module(module) | RibKind::Block(Some(module)) = rib.kind
                     && let Some(did) = find_doc_alias_name(self.r, module, item.name)
                 {
                     return Some((did, item));
@@ -1850,12 +1847,12 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
 
         match (res, source) {
             (
-                Res::Def(DefKind::Macro(MacroKind::Bang), def_id),
+                Res::Def(DefKind::Macro(kinds), def_id),
                 PathSource::Expr(Some(Expr {
                     kind: ExprKind::Index(..) | ExprKind::Call(..), ..
                 }))
                 | PathSource::Struct(_),
-            ) => {
+            ) if kinds.contains(MacroKinds::BANG) => {
                 // Don't suggest macro if it's unstable.
                 let suggestable = def_id.is_local()
                     || self.r.tcx.lookup_stability(def_id).is_none_or(|s| s.is_stable());
@@ -1880,7 +1877,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                     err.note("if you want the `try` keyword, you need Rust 2018 or later");
                 }
             }
-            (Res::Def(DefKind::Macro(MacroKind::Bang), _), _) => {
+            (Res::Def(DefKind::Macro(kinds), _), _) if kinds.contains(MacroKinds::BANG) => {
                 err.span_label(span, fallback_label.to_string());
             }
             (Res::Def(DefKind::TyAlias, def_id), PathSource::Trait(_)) => {
@@ -2459,45 +2456,29 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                     }
                 }
 
+                if let RibKind::Block(Some(module)) = rib.kind {
+                    self.r.add_module_candidates(module, &mut names, &filter_fn, Some(ctxt));
+                } else if let RibKind::Module(module) = rib.kind {
+                    // Encountered a module item, abandon ribs and look into that module and preludes.
+                    let parent_scope = &ParentScope { module, ..self.parent_scope };
+                    self.r.add_scope_set_candidates(
+                        &mut names,
+                        ScopeSet::All(ns),
+                        parent_scope,
+                        ctxt,
+                        filter_fn,
+                    );
+                    break;
+                }
+
                 if let RibKind::MacroDefinition(def) = rib.kind
                     && def == self.r.macro_def(ctxt)
                 {
                     // If an invocation of this macro created `ident`, give up on `ident`
                     // and switch to `ident`'s source from the macro definition.
                     ctxt.remove_mark();
-                    continue;
-                }
-
-                // Items in scope
-                if let RibKind::Module(module) = rib.kind {
-                    // Items from this module
-                    self.r.add_module_candidates(module, &mut names, &filter_fn, Some(ctxt));
-
-                    if let ModuleKind::Block = module.kind {
-                        // We can see through blocks
-                    } else {
-                        // Items from the prelude
-                        if !module.no_implicit_prelude {
-                            names.extend(self.r.extern_prelude.keys().flat_map(|ident| {
-                                let res = Res::Def(DefKind::Mod, CRATE_DEF_ID.to_def_id());
-                                filter_fn(res)
-                                    .then_some(TypoSuggestion::typo_from_ident(ident.0, res))
-                            }));
-
-                            if let Some(prelude) = self.r.prelude {
-                                self.r.add_module_candidates(prelude, &mut names, &filter_fn, None);
-                            }
-                        }
-                        break;
-                    }
                 }
             }
-            // Add primitive types to the mix
-            if filter_fn(Res::PrimTy(PrimTy::Bool)) {
-                names.extend(PrimTy::ALL.iter().map(|prim_ty| {
-                    TypoSuggestion::typo_from_name(prim_ty.name(), Res::PrimTy(*prim_ty))
-                }))
-            }
         } else {
             // Search in module.
             let mod_path = &path[..path.len() - 1];
@@ -3114,7 +3095,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
         } else {
             self.suggest_introducing_lifetime(
                 &mut err,
-                Some(lifetime_ref.ident.name.as_str()),
+                Some(lifetime_ref.ident),
                 |err, _, span, message, suggestion, span_suggs| {
                     err.multipart_suggestion_verbose(
                         message,
@@ -3132,7 +3113,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
     fn suggest_introducing_lifetime(
         &self,
         err: &mut Diag<'_>,
-        name: Option<&str>,
+        name: Option<Ident>,
         suggest: impl Fn(
             &mut Diag<'_>,
             bool,
@@ -3179,7 +3160,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                     let mut rm_inner_binders: FxIndexSet<Span> = Default::default();
                     let (span, sugg) = if span.is_empty() {
                         let mut binder_idents: FxIndexSet<Ident> = Default::default();
-                        binder_idents.insert(Ident::from_str(name.unwrap_or("'a")));
+                        binder_idents.insert(name.unwrap_or(Ident::from_str("'a")));
 
                         // We need to special case binders in the following situation:
                         // Change `T: for<'a> Trait<T> + 'b` to `for<'a, 'b> T: Trait<T> + 'b`
@@ -3209,16 +3190,11 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                             }
                         }
 
-                        let binders_sugg = binder_idents.into_iter().enumerate().fold(
-                            "".to_string(),
-                            |mut binders, (i, x)| {
-                                if i != 0 {
-                                    binders += ", ";
-                                }
-                                binders += x.as_str();
-                                binders
-                            },
-                        );
+                        let binders_sugg: String = binder_idents
+                            .into_iter()
+                            .map(|ident| ident.to_string())
+                            .intersperse(", ".to_owned())
+                            .collect();
                         let sugg = format!(
                             "{}<{}>{}",
                             if higher_ranked { "for" } else { "" },
@@ -3234,7 +3210,8 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                             .source_map()
                             .span_through_char(span, '<')
                             .shrink_to_hi();
-                        let sugg = format!("{}, ", name.unwrap_or("'a"));
+                        let sugg =
+                            format!("{}, ", name.map(|i| i.to_string()).as_deref().unwrap_or("'a"));
                         (span, sugg)
                     };
 
@@ -3242,7 +3219,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
                         let message = Cow::from(format!(
                             "consider making the {} lifetime-generic with a new `{}` lifetime",
                             kind.descr(),
-                            name.unwrap_or("'a"),
+                            name.map(|i| i.to_string()).as_deref().unwrap_or("'a"),
                         ));
                         should_continue = suggest(
                             err,
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index b43f71913d9..2afb52ef4d4 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -15,6 +15,8 @@
 #![feature(arbitrary_self_types)]
 #![feature(assert_matches)]
 #![feature(box_patterns)]
+#![feature(decl_macro)]
+#![feature(default_field_values)]
 #![feature(if_let_guard)]
 #![feature(iter_intersperse)]
 #![feature(rustc_attrs)]
@@ -47,13 +49,14 @@ use rustc_data_structures::intern::Interned;
 use rustc_data_structures::steal::Steal;
 use rustc_data_structures::sync::{FreezeReadGuard, FreezeWriteGuard};
 use rustc_data_structures::unord::{UnordMap, UnordSet};
-use rustc_errors::{Applicability, Diag, ErrCode, ErrorGuaranteed};
+use rustc_errors::{Applicability, Diag, ErrCode, ErrorGuaranteed, LintBuffer};
 use rustc_expand::base::{DeriveResolution, SyntaxExtension, SyntaxExtensionKind};
 use rustc_feature::BUILTIN_ATTRIBUTES;
 use rustc_hir::attrs::StrippedCfgItem;
 use rustc_hir::def::Namespace::{self, *};
 use rustc_hir::def::{
-    self, CtorOf, DefKind, DocLinkResMap, LifetimeRes, NonMacroAttrKind, PartialRes, PerNS,
+    self, CtorOf, DefKind, DocLinkResMap, LifetimeRes, MacroKinds, NonMacroAttrKind, PartialRes,
+    PerNS,
 };
 use rustc_hir::def_id::{CRATE_DEF_ID, CrateNum, DefId, LOCAL_CRATE, LocalDefId, LocalDefIdMap};
 use rustc_hir::definitions::DisambiguatorState;
@@ -69,8 +72,8 @@ use rustc_middle::ty::{
     ResolverGlobalCtxt, TyCtxt, TyCtxtFeed, Visibility,
 };
 use rustc_query_system::ich::StableHashingContext;
+use rustc_session::lint::BuiltinLintDiag;
 use rustc_session::lint::builtin::PRIVATE_MACRO_USE;
-use rustc_session::lint::{BuiltinLintDiag, LintBuffer};
 use rustc_span::hygiene::{ExpnId, LocalExpnId, MacroKind, SyntaxContext, Transparency};
 use rustc_span::{DUMMY_SP, Ident, Macros20NormalizedIdent, Span, Symbol, kw, sym};
 use smallvec::{SmallVec, smallvec};
@@ -113,39 +116,48 @@ impl Determinacy {
 }
 
 /// A specific scope in which a name can be looked up.
-/// This enum is currently used only for early resolution (imports and macros),
-/// but not for late resolution yet.
 #[derive(Clone, Copy, Debug)]
 enum Scope<'ra> {
+    /// Inert attributes registered by derive macros.
     DeriveHelpers(LocalExpnId),
+    /// Inert attributes registered by derive macros, but used before they are actually declared.
+    /// This scope will exist until the compatibility lint `LEGACY_DERIVE_HELPERS`
+    /// is turned into a hard error.
     DeriveHelpersCompat,
+    /// Textual `let`-like scopes introduced by `macro_rules!` items.
     MacroRules(MacroRulesScopeRef<'ra>),
-    // The node ID is for reporting the `PROC_MACRO_DERIVE_RESOLUTION_FALLBACK`
-    // lint if it should be reported.
+    /// Names declared in the given module.
+    /// The node ID is for reporting the `PROC_MACRO_DERIVE_RESOLUTION_FALLBACK`
+    /// lint if it should be reported.
     Module(Module<'ra>, Option<NodeId>),
+    /// Names introduced by `#[macro_use]` attributes on `extern crate` items.
     MacroUsePrelude,
+    /// Built-in attributes.
     BuiltinAttrs,
-    ExternPrelude,
+    /// Extern prelude names introduced by `extern crate` items.
+    ExternPreludeItems,
+    /// Extern prelude names introduced by `--extern` flags.
+    ExternPreludeFlags,
+    /// Tool modules introduced with `#![register_tool]`.
     ToolPrelude,
+    /// Standard library prelude introduced with an internal `#[prelude_import]` import.
     StdLibPrelude,
+    /// Built-in types.
     BuiltinTypes,
 }
 
 /// Names from different contexts may want to visit different subsets of all specific scopes
 /// with different restrictions when looking up the resolution.
-/// This enum is currently used only for early resolution (imports and macros),
-/// but not for late resolution yet.
 #[derive(Clone, Copy, Debug)]
 enum ScopeSet<'ra> {
     /// All scopes with the given namespace.
     All(Namespace),
     /// A module, then extern prelude (used for mixed 2015-2018 mode in macros).
     ModuleAndExternPrelude(Namespace, Module<'ra>),
-    /// All scopes with macro namespace and the given macro kind restriction.
+    /// Just two extern prelude scopes.
+    ExternPrelude,
+    /// Same as `All(MacroNS)`, but with the given macro kind restriction.
     Macro(MacroKind),
-    /// All scopes with the given namespace, used for partially performing late resolution.
-    /// The node id enables lints and is used for reporting them.
-    Late(Namespace, Module<'ra>, Option<NodeId>),
 }
 
 /// Everything you need to know about a name's location to resolve it.
@@ -766,7 +778,10 @@ impl<'ra> std::ops::Deref for Module<'ra> {
 
 impl<'ra> fmt::Debug for Module<'ra> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{:?}", self.res())
+        match self.kind {
+            ModuleKind::Block => write!(f, "block"),
+            ModuleKind::Def(..) => write!(f, "{:?}", self.res()),
+        }
     }
 }
 
@@ -969,8 +984,8 @@ impl<'ra> NameBindingData<'ra> {
         matches!(self.res(), Res::Def(DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy, _))
     }
 
-    fn macro_kind(&self) -> Option<MacroKind> {
-        self.res().macro_kind()
+    fn macro_kinds(&self) -> Option<MacroKinds> {
+        self.res().macro_kinds()
     }
 
     // Suppose that we resolved macro invocation with `invoc_parent_expansion` to binding `binding`
@@ -1012,16 +1027,18 @@ impl<'ra> NameBindingData<'ra> {
 
 #[derive(Default, Clone)]
 struct ExternPreludeEntry<'ra> {
-    binding: Cell<Option<NameBinding<'ra>>>,
+    /// Binding from an `extern crate` item.
+    item_binding: Option<NameBinding<'ra>>,
+    /// Binding from an `--extern` flag, lazily populated on first use.
+    flag_binding: Cell<Option<NameBinding<'ra>>>,
+    /// There was no `--extern` flag introducing this name,
+    /// `flag_binding` doesn't need to be populated.
+    only_item: bool,
+    /// `item_binding` is non-redundant, happens either when `only_item` is true,
+    /// or when `extern crate` introducing `item_binding` used renaming.
     introduced_by_item: bool,
 }
 
-impl ExternPreludeEntry<'_> {
-    fn is_import(&self) -> bool {
-        self.binding.get().is_some_and(|binding| binding.is_import())
-    }
-}
-
 struct DeriveData {
     resolutions: Vec<DeriveResolution>,
     helper_attrs: Vec<(usize, Ident)>,
@@ -1030,14 +1047,13 @@ struct DeriveData {
 
 struct MacroData {
     ext: Arc<SyntaxExtension>,
-    attr_ext: Option<Arc<SyntaxExtension>>,
     nrules: usize,
     macro_rules: bool,
 }
 
 impl MacroData {
     fn new(ext: Arc<SyntaxExtension>) -> MacroData {
-        MacroData { ext, attr_ext: None, nrules: 0, macro_rules: false }
+        MacroData { ext, nrules: 0, macro_rules: false }
     }
 }
 
@@ -1060,7 +1076,7 @@ pub struct Resolver<'ra, 'tcx> {
     /// Assert that we are in speculative resolution mode.
     assert_speculative: bool,
 
-    prelude: Option<Module<'ra>>,
+    prelude: Option<Module<'ra>> = None,
     extern_prelude: FxIndexMap<Macros20NormalizedIdent, ExternPreludeEntry<'ra>>,
 
     /// N.B., this is used only for better diagnostics, not name resolution itself.
@@ -1072,10 +1088,10 @@ pub struct Resolver<'ra, 'tcx> {
     field_visibility_spans: FxHashMap<DefId, Vec<Span>>,
 
     /// All imports known to succeed or fail.
-    determined_imports: Vec<Import<'ra>>,
+    determined_imports: Vec<Import<'ra>> = Vec::new(),
 
     /// All non-determined imports.
-    indeterminate_imports: Vec<Import<'ra>>,
+    indeterminate_imports: Vec<Import<'ra>> = Vec::new(),
 
     // Spans for local variables found during pattern resolution.
     // Used for suggestions during error reporting.
@@ -1126,19 +1142,19 @@ pub struct Resolver<'ra, 'tcx> {
 
     /// Maps glob imports to the names of items actually imported.
     glob_map: FxIndexMap<LocalDefId, FxIndexSet<Symbol>>,
-    glob_error: Option<ErrorGuaranteed>,
-    visibilities_for_hashing: Vec<(LocalDefId, Visibility)>,
+    glob_error: Option<ErrorGuaranteed> = None,
+    visibilities_for_hashing: Vec<(LocalDefId, Visibility)> = Vec::new(),
     used_imports: FxHashSet<NodeId>,
     maybe_unused_trait_imports: FxIndexSet<LocalDefId>,
 
     /// Privacy errors are delayed until the end in order to deduplicate them.
-    privacy_errors: Vec<PrivacyError<'ra>>,
+    privacy_errors: Vec<PrivacyError<'ra>> = Vec::new(),
     /// Ambiguity errors are delayed for deduplication.
-    ambiguity_errors: Vec<AmbiguityError<'ra>>,
+    ambiguity_errors: Vec<AmbiguityError<'ra>> = Vec::new(),
     /// `use` injections are delayed for better placement and deduplication.
-    use_injections: Vec<UseError<'tcx>>,
+    use_injections: Vec<UseError<'tcx>> = Vec::new(),
     /// Crate-local macro expanded `macro_export` referred to by a module-relative path.
-    macro_expanded_macro_export_errors: BTreeSet<(Span, Span)>,
+    macro_expanded_macro_export_errors: BTreeSet<(Span, Span)> = BTreeSet::new(),
 
     arenas: &'ra ResolverArenas<'ra>,
     dummy_binding: NameBinding<'ra>,
@@ -1190,9 +1206,9 @@ pub struct Resolver<'ra, 'tcx> {
     /// Avoid duplicated errors for "name already defined".
     name_already_seen: FxHashMap<Symbol, Span>,
 
-    potentially_unused_imports: Vec<Import<'ra>>,
+    potentially_unused_imports: Vec<Import<'ra>> = Vec::new(),
 
-    potentially_unnecessary_qualifications: Vec<UnnecessaryQualification<'ra>>,
+    potentially_unnecessary_qualifications: Vec<UnnecessaryQualification<'ra>> = Vec::new(),
 
     /// Table for mapping struct IDs into struct constructor IDs,
     /// it's not used during normal resolution, only for better error reporting.
@@ -1201,7 +1217,7 @@ pub struct Resolver<'ra, 'tcx> {
 
     lint_buffer: LintBuffer,
 
-    next_node_id: NodeId,
+    next_node_id: NodeId = CRATE_NODE_ID,
 
     node_id_to_def_id: NodeMap<Feed<'tcx, LocalDefId>>,
 
@@ -1219,17 +1235,17 @@ pub struct Resolver<'ra, 'tcx> {
     item_generics_num_lifetimes: FxHashMap<LocalDefId, usize>,
     delegation_fn_sigs: LocalDefIdMap<DelegationFnSig>,
 
-    main_def: Option<MainDefinition>,
+    main_def: Option<MainDefinition> = None,
     trait_impls: FxIndexMap<DefId, Vec<LocalDefId>>,
     /// A list of proc macro LocalDefIds, written out in the order in which
     /// they are declared in the static array generated by proc_macro_harness.
-    proc_macros: Vec<LocalDefId>,
+    proc_macros: Vec<LocalDefId> = Vec::new(),
     confused_type_with_std_module: FxIndexMap<Span, Span>,
     /// Whether lifetime elision was successful.
     lifetime_elision_allowed: FxHashSet<NodeId>,
 
     /// Names of items that were stripped out via cfg with their corresponding cfg meta item.
-    stripped_cfg_items: Vec<StrippedCfgItem<NodeId>>,
+    stripped_cfg_items: Vec<StrippedCfgItem<NodeId>> = Vec::new(),
 
     effective_visibilities: EffectiveVisibilities,
     doc_link_resolutions: FxIndexMap<LocalDefId, DocLinkResMap>,
@@ -1251,6 +1267,10 @@ pub struct Resolver<'ra, 'tcx> {
 
     mods_with_parse_errors: FxHashSet<DefId>,
 
+    /// Whether `Resolver::register_macros_for_all_crates` has been called once already, as we
+    /// don't need to run it more than once.
+    all_crate_macros_already_registered: bool = false,
+
     // Stores pre-expansion and pre-placeholder-fragment-insertion names for `impl Trait` types
     // that were encountered during resolution. These names are used to generate item names
     // for APITs, so we don't want to leak details of resolution into these names.
@@ -1543,9 +1563,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             field_defaults: Default::default(),
             field_visibility_spans: FxHashMap::default(),
 
-            determined_imports: Vec::new(),
-            indeterminate_imports: Vec::new(),
-
             pat_span_map: Default::default(),
             partial_res_map: Default::default(),
             import_res_map: Default::default(),
@@ -1564,16 +1581,9 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             ast_transform_scopes: FxHashMap::default(),
 
             glob_map: Default::default(),
-            glob_error: None,
-            visibilities_for_hashing: Default::default(),
             used_imports: FxHashSet::default(),
             maybe_unused_trait_imports: Default::default(),
 
-            privacy_errors: Vec::new(),
-            ambiguity_errors: Vec::new(),
-            use_injections: Vec::new(),
-            macro_expanded_macro_export_errors: BTreeSet::new(),
-
             arenas,
             dummy_binding: arenas.new_pub_res_binding(Res::Err, DUMMY_SP, LocalExpnId::ROOT),
             builtin_types_bindings: PrimTy::ALL
@@ -1617,8 +1627,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             derive_data: Default::default(),
             local_macro_def_scopes: FxHashMap::default(),
             name_already_seen: FxHashMap::default(),
-            potentially_unused_imports: Vec::new(),
-            potentially_unnecessary_qualifications: Default::default(),
             struct_constructors: Default::default(),
             unused_macros: Default::default(),
             unused_macro_rules: Default::default(),
@@ -1628,16 +1636,13 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             builtin_attrs: Default::default(),
             containers_deriving_copy: Default::default(),
             lint_buffer: LintBuffer::default(),
-            next_node_id: CRATE_NODE_ID,
             node_id_to_def_id,
             disambiguator: DisambiguatorState::new(),
             placeholder_field_indices: Default::default(),
             invocation_parents,
             legacy_const_generic_args: Default::default(),
             item_generics_num_lifetimes: Default::default(),
-            main_def: Default::default(),
             trait_impls: Default::default(),
-            proc_macros: Default::default(),
             confused_type_with_std_module: Default::default(),
             lifetime_elision_allowed: Default::default(),
             stripped_cfg_items: Default::default(),
@@ -1652,6 +1657,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             current_crate_outer_attr_insert_span,
             mods_with_parse_errors: Default::default(),
             impl_trait_names: Default::default(),
+            ..
         };
 
         let root_parent_scope = ParentScope::module(graph_root, resolver.arenas);
@@ -1879,7 +1885,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             }
         }
 
-        self.cm().visit_scopes(ScopeSet::All(TypeNS), parent_scope, ctxt, |this, scope, _, _| {
+        let scope_set = ScopeSet::All(TypeNS);
+        self.cm().visit_scopes(scope_set, parent_scope, ctxt, None, |this, scope, _, _| {
             match scope {
                 Scope::Module(module, _) => {
                     this.get_mut().traits_in_module(module, assoc_item, &mut found_traits);
@@ -1889,7 +1896,10 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         this.get_mut().traits_in_module(module, assoc_item, &mut found_traits);
                     }
                 }
-                Scope::ExternPrelude | Scope::ToolPrelude | Scope::BuiltinTypes => {}
+                Scope::ExternPreludeItems
+                | Scope::ExternPreludeFlags
+                | Scope::ToolPrelude
+                | Scope::BuiltinTypes => {}
                 _ => unreachable!(),
             }
             None::<()>
@@ -2054,7 +2064,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             // but not introduce it, as used if they are accessed from lexical scope.
             if used == Used::Scope {
                 if let Some(entry) = self.extern_prelude.get(&Macros20NormalizedIdent::new(ident)) {
-                    if !entry.introduced_by_item && entry.binding.get() == Some(used_binding) {
+                    if !entry.introduced_by_item && entry.item_binding == Some(used_binding) {
                         return;
                     }
                 }
@@ -2210,26 +2220,30 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         }
     }
 
-    fn extern_prelude_get<'r>(
+    fn extern_prelude_get_item<'r>(
         mut self: CmResolver<'r, 'ra, 'tcx>,
         ident: Ident,
         finalize: bool,
     ) -> Option<NameBinding<'ra>> {
-        let mut record_use = None;
         let entry = self.extern_prelude.get(&Macros20NormalizedIdent::new(ident));
-        let binding = entry.and_then(|entry| match entry.binding.get() {
-            Some(binding) if binding.is_import() => {
-                if finalize {
-                    record_use = Some(binding);
-                }
-                Some(binding)
+        entry.and_then(|entry| entry.item_binding).map(|binding| {
+            if finalize {
+                self.get_mut().record_use(ident, binding, Used::Scope);
             }
+            binding
+        })
+    }
+
+    fn extern_prelude_get_flag(&self, ident: Ident, finalize: bool) -> Option<NameBinding<'ra>> {
+        let entry = self.extern_prelude.get(&Macros20NormalizedIdent::new(ident));
+        entry.and_then(|entry| match entry.flag_binding.get() {
             Some(binding) => {
                 if finalize {
                     self.cstore_mut().process_path_extern(self.tcx, ident.name, ident.span);
                 }
                 Some(binding)
             }
+            None if entry.only_item => None,
             None => {
                 let crate_id = if finalize {
                     self.cstore_mut().process_path_extern(self.tcx, ident.name, ident.span)
@@ -2241,19 +2255,13 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         let res = Res::Def(DefKind::Mod, crate_id.as_def_id());
                         let binding =
                             self.arenas.new_pub_res_binding(res, DUMMY_SP, LocalExpnId::ROOT);
-                        entry.binding.set(Some(binding));
+                        entry.flag_binding.set(Some(binding));
                         Some(binding)
                     }
                     None => finalize.then_some(self.dummy_binding),
                 }
             }
-        });
-
-        if let Some(binding) = record_use {
-            self.get_mut().record_use(ident, binding, Used::Scope);
-        }
-
-        binding
+        })
     }
 
     /// Rustdoc uses this to resolve doc link paths in a recoverable way. `PathResult<'a>`
@@ -2445,6 +2453,17 @@ fn module_to_string(mut module: Module<'_>) -> Option<String> {
     Some(names_to_string(names.iter().rev().copied()))
 }
 
+#[derive(Copy, Clone, PartialEq, Debug)]
+enum Stage {
+    /// Resolving an import or a macro.
+    /// Used when macro expansion is either not yet finished, or we are finalizing its results.
+    /// Used by default as a more restrictive variant that can produce additional errors.
+    Early,
+    /// Resolving something in late resolution when all imports are resolved
+    /// and all macros are expanded.
+    Late,
+}
+
 #[derive(Copy, Clone, Debug)]
 struct Finalize {
     /// Node ID for linting.
@@ -2457,9 +2476,11 @@ struct Finalize {
     root_span: Span,
     /// Whether to report privacy errors or silently return "no resolution" for them,
     /// similarly to speculative resolution.
-    report_private: bool,
+    report_private: bool = true,
     /// Tracks whether an item is used in scope or used relatively to a module.
-    used: Used,
+    used: Used = Used::Other,
+    /// Finalizing early or late resolution.
+    stage: Stage = Stage::Early,
 }
 
 impl Finalize {
@@ -2468,7 +2489,7 @@ impl Finalize {
     }
 
     fn with_root_span(node_id: NodeId, path_span: Span, root_span: Span) -> Finalize {
-        Finalize { node_id, path_span, root_span, report_private: true, used: Used::Other }
+        Finalize { node_id, path_span, root_span, .. }
     }
 }
 
diff --git a/compiler/rustc_resolve/src/macros.rs b/compiler/rustc_resolve/src/macros.rs
index 9173d0d3ea5..5fa87b4cd9b 100644
--- a/compiler/rustc_resolve/src/macros.rs
+++ b/compiler/rustc_resolve/src/macros.rs
@@ -1,7 +1,6 @@
 //! A bunch of methods and structures more or less related to resolving macros and
 //! interface provided by `Resolver` to macro expander.
 
-use std::any::Any;
 use std::cell::Cell;
 use std::mem;
 use std::sync::Arc;
@@ -13,13 +12,13 @@ use rustc_expand::base::{
     Annotatable, DeriveResolution, Indeterminate, ResolverExpand, SyntaxExtension,
     SyntaxExtensionKind,
 };
+use rustc_expand::compile_declarative_macro;
 use rustc_expand::expand::{
     AstFragment, AstFragmentKind, Invocation, InvocationKind, SupportsMacroExpansion,
 };
-use rustc_expand::{MacroRulesMacroExpander, compile_declarative_macro};
 use rustc_hir::StabilityLevel;
 use rustc_hir::attrs::{CfgEntry, StrippedCfgItem};
-use rustc_hir::def::{self, DefKind, Namespace, NonMacroAttrKind};
+use rustc_hir::def::{self, DefKind, MacroKinds, Namespace, NonMacroAttrKind};
 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId};
 use rustc_middle::middle::stability;
 use rustc_middle::ty::{RegisteredTools, TyCtxt};
@@ -86,22 +85,19 @@ pub(crate) type MacroRulesScopeRef<'ra> = &'ra Cell<MacroRulesScope<'ra>>;
 /// one for attribute-like macros (attributes, derives).
 /// We ignore resolutions from one sub-namespace when searching names in scope for another.
 pub(crate) fn sub_namespace_match(
-    candidate: Option<MacroKind>,
+    candidate: Option<MacroKinds>,
     requirement: Option<MacroKind>,
 ) -> bool {
-    #[derive(PartialEq)]
-    enum SubNS {
-        Bang,
-        AttrLike,
-    }
-    let sub_ns = |kind| match kind {
-        MacroKind::Bang => SubNS::Bang,
-        MacroKind::Attr | MacroKind::Derive => SubNS::AttrLike,
-    };
-    let candidate = candidate.map(sub_ns);
-    let requirement = requirement.map(sub_ns);
     // "No specific sub-namespace" means "matches anything" for both requirements and candidates.
-    candidate.is_none() || requirement.is_none() || candidate == requirement
+    let (Some(candidate), Some(requirement)) = (candidate, requirement) else {
+        return true;
+    };
+    match requirement {
+        MacroKind::Bang => candidate.contains(MacroKinds::BANG),
+        MacroKind::Attr | MacroKind::Derive => {
+            candidate.intersects(MacroKinds::ATTR | MacroKinds::DERIVE)
+        }
+    }
 }
 
 // We don't want to format a path using pretty-printing,
@@ -323,6 +319,7 @@ impl<'ra, 'tcx> ResolverExpand for Resolver<'ra, 'tcx> {
                 parent_scope.expansion,
                 span,
                 fast_print_path(path),
+                kind,
                 def_id,
                 def_id.map(|def_id| self.macro_def_scope(def_id).nearest_parent_mod()),
             ),
@@ -356,11 +353,7 @@ impl<'ra, 'tcx> ResolverExpand for Resolver<'ra, 'tcx> {
             }
             let def_id = self.local_def_id(node_id);
             let m = &self.local_macro_map[&def_id];
-            let SyntaxExtensionKind::LegacyBang(ref ext) = m.ext.kind else {
-                continue;
-            };
-            let ext: &dyn Any = ext.as_ref();
-            let Some(m) = ext.downcast_ref::<MacroRulesMacroExpander>() else {
+            let SyntaxExtensionKind::MacroRules(ref m) = m.ext.kind else {
                 continue;
             };
             for arm_i in unused_arms.iter() {
@@ -405,7 +398,7 @@ impl<'ra, 'tcx> ResolverExpand for Resolver<'ra, 'tcx> {
                 resolution.exts = Some(
                     match self.cm().resolve_macro_path(
                         &resolution.path,
-                        Some(MacroKind::Derive),
+                        MacroKind::Derive,
                         &parent_scope,
                         true,
                         force,
@@ -570,7 +563,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
     ) -> Result<(Arc<SyntaxExtension>, Res), Indeterminate> {
         let (ext, res) = match self.cm().resolve_macro_or_delegation_path(
             path,
-            Some(kind),
+            kind,
             parent_scope,
             true,
             force,
@@ -633,7 +626,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
 
         self.check_stability_and_deprecation(&ext, path, node_id);
 
-        let unexpected_res = if ext.macro_kind() != kind {
+        let unexpected_res = if !ext.macro_kinds().contains(kind.into()) {
             Some((kind.article(), kind.descr_expected()))
         } else if matches!(res, Res::Def(..)) {
             match supports_macro_expansion {
@@ -665,7 +658,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             // Suggest moving the macro out of the derive() if the macro isn't Derive
             if !path.span.from_expansion()
                 && kind == MacroKind::Derive
-                && ext.macro_kind() != MacroKind::Derive
+                && !ext.macro_kinds().contains(MacroKinds::DERIVE)
+                && ext.macro_kinds().contains(MacroKinds::ATTR)
             {
                 err.remove_surrounding_derive = Some(RemoveSurroundingDerive { span: path.span });
                 err.add_as_non_derive = Some(AddAsNonDerive { macro_path: &path_str });
@@ -716,7 +710,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
     pub(crate) fn resolve_macro_path<'r>(
         self: CmResolver<'r, 'ra, 'tcx>,
         path: &ast::Path,
-        kind: Option<MacroKind>,
+        kind: MacroKind,
         parent_scope: &ParentScope<'ra>,
         trace: bool,
         force: bool,
@@ -739,7 +733,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
     fn resolve_macro_or_delegation_path<'r>(
         mut self: CmResolver<'r, 'ra, 'tcx>,
         ast_path: &ast::Path,
-        kind: Option<MacroKind>,
+        kind: MacroKind,
         parent_scope: &ParentScope<'ra>,
         trace: bool,
         force: bool,
@@ -753,7 +747,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
 
         // Possibly apply the macro helper hack
         if deleg_impl.is_none()
-            && kind == Some(MacroKind::Bang)
+            && kind == MacroKind::Bang
             && let [segment] = path.as_slice()
             && segment.ident.span.ctxt().outer_expn_data().local_inner_macros
         {
@@ -781,7 +775,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             };
 
             if trace {
-                let kind = kind.expect("macro kind must be specified if tracing is enabled");
                 // FIXME: Should be an output of Speculative Resolution.
                 self.multi_segment_macro_resolutions.borrow_mut().push((
                     path,
@@ -796,10 +789,9 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             self.prohibit_imported_non_macro_attrs(None, res.ok(), path_span);
             res
         } else {
-            let scope_set = kind.map_or(ScopeSet::All(MacroNS), ScopeSet::Macro);
-            let binding = self.reborrow().early_resolve_ident_in_lexical_scope(
+            let binding = self.reborrow().resolve_ident_in_scope_set(
                 path[0].ident,
-                scope_set,
+                ScopeSet::Macro(kind),
                 parent_scope,
                 None,
                 force,
@@ -811,7 +803,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             }
 
             if trace {
-                let kind = kind.expect("macro kind must be specified if tracing is enabled");
                 // FIXME: Should be an output of Speculative Resolution.
                 self.single_segment_macro_resolutions.borrow_mut().push((
                     path[0].ident,
@@ -842,10 +833,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 }
                 _ => None,
             },
-            None => self.get_macro(res).map(|macro_data| match kind {
-                Some(MacroKind::Attr) if let Some(ref ext) = macro_data.attr_ext => Arc::clone(ext),
-                _ => Arc::clone(&macro_data.ext),
-            }),
+            None => self.get_macro(res).map(|macro_data| Arc::clone(&macro_data.ext)),
         };
         Ok((ext, res))
     }
@@ -963,7 +951,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         // FIXME: Should be an output of Speculative Resolution.
         let macro_resolutions = self.single_segment_macro_resolutions.take();
         for (ident, kind, parent_scope, initial_binding, sugg_span) in macro_resolutions {
-            match self.cm().early_resolve_ident_in_lexical_scope(
+            match self.cm().resolve_ident_in_scope_set(
                 ident,
                 ScopeSet::Macro(kind),
                 &parent_scope,
@@ -1018,7 +1006,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
 
         let builtin_attrs = mem::take(&mut self.builtin_attrs);
         for (ident, parent_scope) in builtin_attrs {
-            let _ = self.cm().early_resolve_ident_in_lexical_scope(
+            let _ = self.cm().resolve_ident_in_scope_set(
                 ident,
                 ScopeSet::Macro(MacroKind::Attr),
                 &parent_scope,
@@ -1114,7 +1102,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             && let Some(binding) = binding
             // This is a `macro_rules` itself, not some import.
             && let NameBindingKind::Res(res) = binding.kind
-            && let Res::Def(DefKind::Macro(MacroKind::Bang), def_id) = res
+            && let Res::Def(DefKind::Macro(kinds), def_id) = res
+            && kinds.contains(MacroKinds::BANG)
             // And the `macro_rules` is defined inside the attribute's module,
             // so it cannot be in scope unless imported.
             && self.tcx.is_descendant_of(def_id, mod_def_id.to_def_id())
@@ -1123,7 +1112,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             // If such resolution is successful and gives the same result
             // (e.g. if the macro is re-imported), then silence the lint.
             let no_macro_rules = self.arenas.alloc_macro_rules_scope(MacroRulesScope::Empty);
-            let fallback_binding = self.reborrow().early_resolve_ident_in_lexical_scope(
+            let fallback_binding = self.reborrow().resolve_ident_in_scope_set(
                 path.segments[0].ident,
                 ScopeSet::Macro(MacroKind::Bang),
                 &ParentScope { macro_rules: no_macro_rules, ..*parent_scope },
@@ -1161,8 +1150,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         // Reserve some names that are not quite covered by the general check
         // performed on `Resolver::builtin_attrs`.
         if ident.name == sym::cfg || ident.name == sym::cfg_attr {
-            let macro_kind = self.get_macro(res).map(|macro_data| macro_data.ext.macro_kind());
-            if macro_kind.is_some() && sub_namespace_match(macro_kind, Some(MacroKind::Attr)) {
+            let macro_kinds = self.get_macro(res).map(|macro_data| macro_data.ext.macro_kinds());
+            if macro_kinds.is_some() && sub_namespace_match(macro_kinds, Some(MacroKind::Attr)) {
                 self.dcx()
                     .emit_err(errors::NameReservedInAttributeNamespace { span: ident.span, ident });
             }
@@ -1181,7 +1170,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         node_id: NodeId,
         edition: Edition,
     ) -> MacroData {
-        let (mut ext, mut attr_ext, mut nrules) = compile_declarative_macro(
+        let (mut ext, mut nrules) = compile_declarative_macro(
             self.tcx.sess,
             self.tcx.features(),
             macro_def,
@@ -1198,14 +1187,13 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 // The macro is a built-in, replace its expander function
                 // while still taking everything else from the source code.
                 ext.kind = builtin_ext_kind.clone();
-                attr_ext = None;
                 nrules = 0;
             } else {
                 self.dcx().emit_err(errors::CannotFindBuiltinMacroWithName { span, ident });
             }
         }
 
-        MacroData { ext: Arc::new(ext), attr_ext, nrules, macro_rules: macro_def.macro_rules }
+        MacroData { ext: Arc::new(ext), nrules, macro_rules: macro_def.macro_rules }
     }
 
     fn path_accessible(
diff --git a/compiler/rustc_resolve/src/rustdoc.rs b/compiler/rustc_resolve/src/rustdoc.rs
index 6450f63472c..804792c6f28 100644
--- a/compiler/rustc_resolve/src/rustdoc.rs
+++ b/compiler/rustc_resolve/src/rustdoc.rs
@@ -207,8 +207,10 @@ pub fn attrs_to_doc_fragments<'a, A: AttributeExt + Clone + 'a>(
     attrs: impl Iterator<Item = (&'a A, Option<DefId>)>,
     doc_only: bool,
 ) -> (Vec<DocFragment>, ThinVec<A>) {
-    let mut doc_fragments = Vec::new();
-    let mut other_attrs = ThinVec::<A>::new();
+    let (min_size, max_size) = attrs.size_hint();
+    let size_hint = max_size.unwrap_or(min_size);
+    let mut doc_fragments = Vec::with_capacity(size_hint);
+    let mut other_attrs = ThinVec::<A>::with_capacity(if doc_only { 0 } else { size_hint });
     for (attr, item_id) in attrs {
         if let Some((doc_str, comment_kind)) = attr.doc_str_and_comment_kind() {
             let doc = beautify_doc_string(doc_str, comment_kind);
@@ -230,6 +232,9 @@ pub fn attrs_to_doc_fragments<'a, A: AttributeExt + Clone + 'a>(
         }
     }
 
+    doc_fragments.shrink_to_fit();
+    other_attrs.shrink_to_fit();
+
     unindent_doc_fragments(&mut doc_fragments);
 
     (doc_fragments, other_attrs)
@@ -368,8 +373,8 @@ pub fn inner_docs(attrs: &[impl AttributeExt]) -> bool {
     true
 }
 
-/// Has `#[rustc_doc_primitive]` or `#[doc(keyword)]`.
-pub fn has_primitive_or_keyword_docs(attrs: &[impl AttributeExt]) -> bool {
+/// Has `#[rustc_doc_primitive]` or `#[doc(keyword)]` or `#[doc(attribute)]`.
+pub fn has_primitive_or_keyword_or_attribute_docs(attrs: &[impl AttributeExt]) -> bool {
     for attr in attrs {
         if attr.has_name(sym::rustc_doc_primitive) {
             return true;
@@ -377,7 +382,7 @@ pub fn has_primitive_or_keyword_docs(attrs: &[impl AttributeExt]) -> bool {
             && let Some(items) = attr.meta_item_list()
         {
             for item in items {
-                if item.has_name(sym::keyword) {
+                if item.has_name(sym::keyword) || item.has_name(sym::attribute) {
                     return true;
                 }
             }
diff --git a/compiler/rustc_sanitizers/Cargo.toml b/compiler/rustc_sanitizers/Cargo.toml
index 9069d2c233d..3dbeaa435f3 100644
--- a/compiler/rustc_sanitizers/Cargo.toml
+++ b/compiler/rustc_sanitizers/Cargo.toml
@@ -5,7 +5,7 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-bitflags = "2.5.0"
+bitflags.workspace = true
 rustc_abi = { path = "../rustc_abi" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_hir = { path = "../rustc_hir" }
@@ -13,6 +13,6 @@ rustc_middle = { path = "../rustc_middle" }
 rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 rustc_trait_selection = { path = "../rustc_trait_selection" }
-tracing = "0.1"
+tracing.workspace = true
 twox-hash = "1.6.3"
 # tidy-alphabetical-end
diff --git a/compiler/rustc_serialize/Cargo.toml b/compiler/rustc_serialize/Cargo.toml
index 948242352e7..e9959735f9f 100644
--- a/compiler/rustc_serialize/Cargo.toml
+++ b/compiler/rustc_serialize/Cargo.toml
@@ -8,7 +8,7 @@ edition = "2024"
 indexmap = "2.0.0"
 rustc_hashes = { path = "../rustc_hashes" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec = "0.2.12"
+thin-vec.workspace = true
 # tidy-alphabetical-end
 
 [dev-dependencies]
diff --git a/compiler/rustc_session/Cargo.toml b/compiler/rustc_session/Cargo.toml
index 0516982aeab..97789b198a4 100644
--- a/compiler/rustc_session/Cargo.toml
+++ b/compiler/rustc_session/Cargo.toml
@@ -5,7 +5,7 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-bitflags = "2.4.1"
+bitflags.workspace = true
 getopts = "0.2"
 rand = "0.9.0"
 rustc_abi = { path = "../rustc_abi" }
@@ -23,12 +23,14 @@ rustc_serialize = { path = "../rustc_serialize" }
 rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 termize = "0.2"
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
 
 [target.'cfg(unix)'.dependencies]
+# FIXME: Remove this pin once this rustix issue is resolved
+# https://github.com/bytecodealliance/rustix/issues/1496
 # tidy-alphabetical-start
-libc = "0.2"
+libc = "=0.2.174"
 # tidy-alphabetical-end
 
 [target.'cfg(windows)'.dependencies.windows]
diff --git a/compiler/rustc_session/messages.ftl b/compiler/rustc_session/messages.ftl
index 528c52eace7..b46e8ab4fdc 100644
--- a/compiler/rustc_session/messages.ftl
+++ b/compiler/rustc_session/messages.ftl
@@ -49,6 +49,8 @@ session_hexadecimal_float_literal_not_supported = hexadecimal float literal is n
 session_incompatible_linker_flavor = linker flavor `{$flavor}` is incompatible with the current target
     .note = compatible flavors are: {$compatible_list}
 
+session_indirect_branch_cs_prefix_requires_x86_or_x86_64 = `-Zindirect-branch-cs-prefix` is only supported on x86 and x86_64
+
 session_instrumentation_not_supported = {$us} instrumentation is not supported for this target
 
 session_int_literal_too_large = integer literal is too large
@@ -129,6 +131,10 @@ session_target_small_data_threshold_not_supported = `-Z small-data-threshold` is
 
 session_target_stack_protector_not_supported = `-Z stack-protector={$stack_protector}` is not supported for target {$target_triple} and will be ignored
 
+session_unexpected_builtin_cfg = unexpected `--cfg {$cfg}` flag
+    .controlled_by = config `{$cfg_name}` is only supposed to be controlled by `{$controlled_by}`
+    .incoherent = manually setting a built-in cfg can and does create incoherent behaviors
+
 session_unleashed_feature_help_named = skipping check for `{$gate}` feature
 session_unleashed_feature_help_unnamed = skipping check that does not even have a feature gate
 
diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index c665c85d1fe..9793d8091e2 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -16,10 +16,11 @@ use std::{cmp, fmt, fs, iter};
 
 use externs::{ExternOpt, split_extern_opt};
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
-use rustc_data_structures::stable_hasher::{StableOrd, ToStableHashKey};
+use rustc_data_structures::stable_hasher::{StableHasher, StableOrd, ToStableHashKey};
 use rustc_errors::emitter::HumanReadableErrorType;
 use rustc_errors::{ColorConfig, DiagArgValue, DiagCtxtFlags, IntoDiagArg};
 use rustc_feature::UnstableFeatures;
+use rustc_hashes::Hash64;
 use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use rustc_span::edition::{DEFAULT_EDITION, EDITION_NAME_LIST, Edition, LATEST_STABLE_EDITION};
 use rustc_span::source_map::FilePathMapping;
@@ -1195,7 +1196,25 @@ pub struct OutputFilenames {
 pub const RLINK_EXT: &str = "rlink";
 pub const RUST_CGU_EXT: &str = "rcgu";
 pub const DWARF_OBJECT_EXT: &str = "dwo";
+pub const MAX_FILENAME_LENGTH: usize = 143; // ecryptfs limits filenames to 143 bytes see #49914
 
+/// Ensure the filename is not too long, as some filesystems have a limit.
+/// If the filename is too long, hash part of it and append the hash to the filename.
+/// This is a workaround for long crate names generating overly long filenames.
+fn maybe_strip_file_name(mut path: PathBuf) -> PathBuf {
+    if path.file_name().map_or(0, |name| name.len()) > MAX_FILENAME_LENGTH {
+        let filename = path.file_name().unwrap().to_string_lossy();
+        let hash_len = 64 / 4; // Hash64 is 64 bits encoded in hex
+        let stripped_len = filename.len() - MAX_FILENAME_LENGTH + hash_len;
+
+        let mut hasher = StableHasher::new();
+        filename[..stripped_len].hash(&mut hasher);
+        let hash = hasher.finish::<Hash64>();
+
+        path.set_file_name(format!("{:x}-{}", hash, &filename[stripped_len..]));
+    }
+    path
+}
 impl OutputFilenames {
     pub fn new(
         out_directory: PathBuf,
@@ -1288,7 +1307,7 @@ impl OutputFilenames {
         }
 
         let temps_directory = self.temps_directory.as_ref().unwrap_or(&self.out_directory);
-        self.with_directory_and_extension(temps_directory, &extension)
+        maybe_strip_file_name(self.with_directory_and_extension(temps_directory, &extension))
     }
 
     pub fn temp_path_for_diagnostic(&self, ext: &str) -> PathBuf {
@@ -2828,16 +2847,27 @@ pub fn build_session_options(early_dcx: &mut EarlyDiagCtxt, matches: &getopts::M
         // This is the location used by the `rustc-dev` `rustup` component.
         real_source_base_dir("lib/rustlib/rustc-src/rust", "compiler/rustc/src/main.rs");
 
-    let mut search_paths = vec![];
-    for s in &matches.opt_strs("L") {
-        search_paths.push(SearchPath::from_cli_opt(
-            sysroot.path(),
-            &target_triple,
-            early_dcx,
-            s,
-            unstable_opts.unstable_options,
-        ));
-    }
+    // We eagerly scan all files in each passed -L path. If the same directory is passed multiple
+    // times, and the directory contains a lot of files, this can take a lot of time.
+    // So we remove -L paths that were passed multiple times, and keep only the first occurrence.
+    // We still have to keep the original order of the -L arguments.
+    let search_paths: Vec<SearchPath> = {
+        let mut seen_search_paths = FxHashSet::default();
+        let search_path_matches: Vec<String> = matches.opt_strs("L");
+        search_path_matches
+            .iter()
+            .filter(|p| seen_search_paths.insert(*p))
+            .map(|path| {
+                SearchPath::from_cli_opt(
+                    sysroot.path(),
+                    &target_triple,
+                    early_dcx,
+                    &path,
+                    unstable_opts.unstable_options,
+                )
+            })
+            .collect()
+    };
 
     let working_dir = std::env::current_dir().unwrap_or_else(|e| {
         early_dcx.early_fatal(format!("Current directory is invalid: {e}"));
diff --git a/compiler/rustc_session/src/config/cfg.rs b/compiler/rustc_session/src/config/cfg.rs
index 62891eb4f26..8f63ce6f0ae 100644
--- a/compiler/rustc_session/src/config/cfg.rs
+++ b/compiler/rustc_session/src/config/cfg.rs
@@ -26,13 +26,12 @@ use std::iter;
 use rustc_abi::Align;
 use rustc_ast::ast;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
-use rustc_lint_defs::BuiltinLintDiag;
 use rustc_lint_defs::builtin::EXPLICIT_BUILTIN_CFGS_IN_FLAGS;
 use rustc_span::{Symbol, sym};
 use rustc_target::spec::{PanicStrategy, RelocModel, SanitizerSet, Target};
 
-use crate::Session;
 use crate::config::{CrateType, FmtDebug};
+use crate::{Session, errors};
 
 /// The parsed `--cfg` options that define the compilation environment of the
 /// crate, used to drive conditional compilation.
@@ -99,7 +98,7 @@ pub(crate) fn disallow_cfgs(sess: &Session, user_cfgs: &Cfg) {
             EXPLICIT_BUILTIN_CFGS_IN_FLAGS,
             None,
             ast::CRATE_NODE_ID,
-            BuiltinLintDiag::UnexpectedBuiltinCfg { cfg, cfg_name, controlled_by },
+            errors::UnexpectedBuiltinCfg { cfg, cfg_name, controlled_by }.into(),
         )
     };
 
diff --git a/compiler/rustc_session/src/config/native_libs.rs b/compiler/rustc_session/src/config/native_libs.rs
index f1f0aeb5e59..50a0593f887 100644
--- a/compiler/rustc_session/src/config/native_libs.rs
+++ b/compiler/rustc_session/src/config/native_libs.rs
@@ -5,10 +5,11 @@
 //! which have their own parser in `rustc_metadata`.)
 
 use rustc_feature::UnstableFeatures;
+use rustc_hir::attrs::NativeLibKind;
 
 use crate::EarlyDiagCtxt;
 use crate::config::UnstableOptions;
-use crate::utils::{NativeLib, NativeLibKind};
+use crate::utils::NativeLib;
 
 #[cfg(test)]
 mod tests;
diff --git a/compiler/rustc_session/src/cstore.rs b/compiler/rustc_session/src/cstore.rs
index 4cfc745dec2..30f6256a75e 100644
--- a/compiler/rustc_session/src/cstore.rs
+++ b/compiler/rustc_session/src/cstore.rs
@@ -6,8 +6,8 @@ use std::any::Any;
 use std::path::PathBuf;
 
 use rustc_abi::ExternAbi;
-use rustc_ast as ast;
 use rustc_data_structures::sync::{self, AppendOnlyIndexVec, FreezeLock};
+use rustc_hir::attrs::{CfgEntry, NativeLibKind, PeImportNameType};
 use rustc_hir::def_id::{
     CrateNum, DefId, LOCAL_CRATE, LocalDefId, StableCrateId, StableCrateIdMap,
 };
@@ -16,7 +16,6 @@ use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use rustc_span::{Span, Symbol};
 
 use crate::search_paths::PathKind;
-use crate::utils::NativeLibKind;
 
 // lonely orphan structs and enums looking for a better home
 
@@ -72,7 +71,7 @@ pub struct NativeLib {
     pub name: Symbol,
     /// If packed_bundled_libs enabled, actual filename of library is stored.
     pub filename: Option<Symbol>,
-    pub cfg: Option<ast::MetaItemInner>,
+    pub cfg: Option<CfgEntry>,
     pub foreign_module: Option<DefId>,
     pub verbatim: Option<bool>,
     pub dll_imports: Vec<DllImport>,
@@ -88,25 +87,6 @@ impl NativeLib {
     }
 }
 
-/// Different ways that the PE Format can decorate a symbol name.
-/// From <https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-name-type>
-#[derive(Copy, Clone, Debug, Encodable, Decodable, HashStable_Generic, PartialEq, Eq)]
-pub enum PeImportNameType {
-    /// IMPORT_ORDINAL
-    /// Uses the ordinal (i.e., a number) rather than the name.
-    Ordinal(u16),
-    /// Same as IMPORT_NAME
-    /// Name is decorated with all prefixes and suffixes.
-    Decorated,
-    /// Same as IMPORT_NAME_NOPREFIX
-    /// Prefix (e.g., the leading `_` or `@`) is skipped, but suffix is kept.
-    NoPrefix,
-    /// Same as IMPORT_NAME_UNDECORATE
-    /// Prefix (e.g., the leading `_` or `@`) and suffix (the first `@` and all
-    /// trailing characters) are skipped.
-    Undecorated,
-}
-
 #[derive(Clone, Debug, Encodable, Decodable, HashStable_Generic)]
 pub struct DllImport {
     pub name: Symbol,
diff --git a/compiler/rustc_session/src/errors.rs b/compiler/rustc_session/src/errors.rs
index bf95014843d..34da54a20bf 100644
--- a/compiler/rustc_session/src/errors.rs
+++ b/compiler/rustc_session/src/errors.rs
@@ -7,7 +7,7 @@ use rustc_errors::{
     Diag, DiagCtxtHandle, DiagMessage, Diagnostic, EmissionGuarantee, ErrorGuaranteed, Level,
     MultiSpan,
 };
-use rustc_macros::{Diagnostic, Subdiagnostic};
+use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
 use rustc_span::{Span, Symbol};
 use rustc_target::spec::{SplitDebuginfo, StackProtector, TargetTuple};
 
@@ -472,6 +472,10 @@ pub(crate) struct FunctionReturnRequiresX86OrX8664;
 pub(crate) struct FunctionReturnThunkExternRequiresNonLargeCodeModel;
 
 #[derive(Diagnostic)]
+#[diag(session_indirect_branch_cs_prefix_requires_x86_or_x86_64)]
+pub(crate) struct IndirectBranchCsPrefixRequiresX86OrX8664;
+
+#[derive(Diagnostic)]
 #[diag(session_unsupported_regparm)]
 pub(crate) struct UnsupportedRegparm {
     pub(crate) regparm: u32,
@@ -501,3 +505,13 @@ pub(crate) struct SoftFloatIgnored;
 #[note]
 #[note(session_soft_float_deprecated_issue)]
 pub(crate) struct SoftFloatDeprecated;
+
+#[derive(LintDiagnostic)]
+#[diag(session_unexpected_builtin_cfg)]
+#[note(session_controlled_by)]
+#[note(session_incoherent)]
+pub(crate) struct UnexpectedBuiltinCfg {
+    pub(crate) cfg: String,
+    pub(crate) cfg_name: Symbol,
+    pub(crate) controlled_by: &'static str,
+}
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index 7c18fd89098..6d5be2d92cd 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -2165,6 +2165,8 @@ options! {
         "hash algorithm of source files used to check freshness in cargo (`blake3` or `sha256`)"),
     codegen_backend: Option<String> = (None, parse_opt_string, [TRACKED],
         "the backend to use"),
+    codegen_source_order: bool = (false, parse_bool, [UNTRACKED],
+        "emit mono items in the order of spans in source files (default: no)"),
     contract_checks: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "emit runtime checks for contract pre- and post-conditions (default: no)"),
     coverage_options: CoverageOptions = (CoverageOptions::default(), parse_coverage_options, [TRACKED],
@@ -2293,6 +2295,8 @@ options! {
         - hashes of green query instances
         - hash collisions of query keys
         - hash collisions when creating dep-nodes"),
+    indirect_branch_cs_prefix: bool = (false, parse_bool, [TRACKED TARGET_MODIFIER],
+        "add `cs` prefix to `call` and `jmp` to indirect thunks (default: no)"),
     inline_llvm: bool = (true, parse_bool, [TRACKED],
         "enable LLVM inlining (default: yes)"),
     inline_mir: Option<bool> = (None, parse_opt_bool, [TRACKED],
diff --git a/compiler/rustc_session/src/parse.rs b/compiler/rustc_session/src/parse.rs
index 426480f0dba..9048c51d5b4 100644
--- a/compiler/rustc_session/src/parse.rs
+++ b/compiler/rustc_session/src/parse.rs
@@ -11,8 +11,8 @@ use rustc_data_structures::sync::{AppendOnlyVec, Lock};
 use rustc_errors::emitter::{FatalOnlyEmitter, HumanEmitter, stderr_destination};
 use rustc_errors::translation::Translator;
 use rustc_errors::{
-    ColorConfig, Diag, DiagCtxt, DiagCtxtHandle, DiagMessage, EmissionGuarantee, MultiSpan,
-    StashKey,
+    BufferedEarlyLint, ColorConfig, DecorateDiagCompat, Diag, DiagCtxt, DiagCtxtHandle,
+    DiagMessage, EmissionGuarantee, MultiSpan, StashKey,
 };
 use rustc_feature::{GateIssue, UnstableFeatures, find_feature_issue};
 use rustc_span::edition::Edition;
@@ -27,7 +27,7 @@ use crate::errors::{
     FeatureDiagnosticSuggestion, FeatureGateError, SuggestUpgradeCompiler,
 };
 use crate::lint::builtin::UNSTABLE_SYNTAX_PRE_EXPANSION;
-use crate::lint::{BufferedEarlyLint, BuiltinLintDiag, Lint, LintId};
+use crate::lint::{Lint, LintId};
 
 /// Collected spans during parsing for places where a certain feature was
 /// used and should be feature gated accordingly in `check_crate`.
@@ -342,17 +342,17 @@ impl ParseSess {
         lint: &'static Lint,
         span: impl Into<MultiSpan>,
         node_id: NodeId,
-        diagnostic: BuiltinLintDiag,
+        diagnostic: impl Into<DecorateDiagCompat>,
     ) {
-        self.opt_span_buffer_lint(lint, Some(span.into()), node_id, diagnostic)
+        self.opt_span_buffer_lint(lint, Some(span.into()), node_id, diagnostic.into())
     }
 
-    pub fn opt_span_buffer_lint(
+    pub(crate) fn opt_span_buffer_lint(
         &self,
         lint: &'static Lint,
         span: Option<MultiSpan>,
         node_id: NodeId,
-        diagnostic: BuiltinLintDiag,
+        diagnostic: DecorateDiagCompat,
     ) {
         self.buffered_lints.with_lock(|buffered_lints| {
             buffered_lints.push(BufferedEarlyLint {
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index c6956cf5f23..96767d05439 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -7,6 +7,7 @@ use std::sync::atomic::AtomicBool;
 use std::{env, fmt, io};
 
 use rand::{RngCore, rng};
+use rustc_ast::NodeId;
 use rustc_data_structures::base_n::{CASE_INSENSITIVE, ToBaseN};
 use rustc_data_structures::flock;
 use rustc_data_structures::fx::{FxHashMap, FxIndexSet};
@@ -22,7 +23,7 @@ use rustc_errors::timings::TimingSectionHandler;
 use rustc_errors::translation::Translator;
 use rustc_errors::{
     Diag, DiagCtxt, DiagCtxtHandle, DiagMessage, Diagnostic, ErrorGuaranteed, FatalAbort,
-    TerminalUrl, fallback_fluent_bundle,
+    LintEmitter, TerminalUrl, fallback_fluent_bundle,
 };
 use rustc_macros::HashStable_Generic;
 pub use rustc_span::def_id::StableCrateId;
@@ -44,6 +45,7 @@ use crate::config::{
     SwitchWithOptPath,
 };
 use crate::filesearch::FileSearch;
+use crate::lint::LintId;
 use crate::parse::{ParseSess, add_feature_diagnostics};
 use crate::search_paths::SearchPath;
 use crate::{errors, filesearch, lint};
@@ -139,7 +141,10 @@ pub struct CompilerIO {
     pub temps_dir: Option<PathBuf>,
 }
 
-pub trait LintStoreMarker: Any + DynSync + DynSend {}
+pub trait DynLintStore: Any + DynSync + DynSend {
+    /// Provides a way to access lint groups without depending on `rustc_lint`
+    fn lint_groups_iter(&self) -> Box<dyn Iterator<Item = LintGroup> + '_>;
+}
 
 /// Represents the data associated with a compilation
 /// session for a single crate.
@@ -164,7 +169,7 @@ pub struct Session {
     pub code_stats: CodeStats,
 
     /// This only ever stores a `LintStore` but we don't want a dependency on that type here.
-    pub lint_store: Option<Arc<dyn LintStoreMarker>>,
+    pub lint_store: Option<Arc<dyn DynLintStore>>,
 
     /// Cap lint level specified by a driver specifically.
     pub driver_lint_caps: FxHashMap<lint::LintId, lint::Level>,
@@ -219,6 +224,20 @@ pub struct Session {
     pub invocation_temp: Option<String>,
 }
 
+impl LintEmitter for &'_ Session {
+    type Id = NodeId;
+
+    fn emit_node_span_lint(
+        self,
+        lint: &'static rustc_lint_defs::Lint,
+        node_id: Self::Id,
+        span: impl Into<rustc_errors::MultiSpan>,
+        decorator: impl for<'a> rustc_errors::LintDiagnostic<'a, ()> + DynSend + 'static,
+    ) {
+        self.psess.buffer_lint(lint, span, node_id, decorator);
+    }
+}
+
 #[derive(Clone, Copy)]
 pub enum CodegenUnits {
     /// Specified by the user. In this case we try fairly hard to produce the
@@ -240,6 +259,12 @@ impl CodegenUnits {
     }
 }
 
+pub struct LintGroup {
+    pub name: &'static str,
+    pub lints: Vec<LintId>,
+    pub is_externally_loaded: bool,
+}
+
 impl Session {
     pub fn miri_unleashed_feature(&self, span: Span, feature_gate: Option<Symbol>) {
         self.miri_unleashed_features.lock().push((span, feature_gate));
@@ -596,6 +621,13 @@ impl Session {
             (&*self.target.staticlib_prefix, &*self.target.staticlib_suffix)
         }
     }
+
+    pub fn lint_groups_iter(&self) -> Box<dyn Iterator<Item = LintGroup> + '_> {
+        match self.lint_store {
+            Some(ref lint_store) => lint_store.lint_groups_iter(),
+            None => Box::new(std::iter::empty()),
+        }
+    }
 }
 
 // JUSTIFICATION: defn of the suggested wrapper fns
@@ -1368,6 +1400,12 @@ fn validate_commandline_args_with_session_available(sess: &Session) {
         }
     }
 
+    if sess.opts.unstable_opts.indirect_branch_cs_prefix {
+        if sess.target.arch != "x86" && sess.target.arch != "x86_64" {
+            sess.dcx().emit_err(errors::IndirectBranchCsPrefixRequiresX86OrX8664);
+        }
+    }
+
     if let Some(regparm) = sess.opts.unstable_opts.regparm {
         if regparm > 3 {
             sess.dcx().emit_err(errors::UnsupportedRegparm { regparm });
diff --git a/compiler/rustc_session/src/utils.rs b/compiler/rustc_session/src/utils.rs
index e9ddd66b5e8..c64d9bc1efe 100644
--- a/compiler/rustc_session/src/utils.rs
+++ b/compiler/rustc_session/src/utils.rs
@@ -3,6 +3,7 @@ use std::sync::OnceLock;
 
 use rustc_data_structures::profiling::VerboseTimingGuard;
 use rustc_fs_util::try_canonicalize;
+use rustc_hir::attrs::NativeLibKind;
 use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 
 use crate::session::Session;
@@ -17,69 +18,6 @@ impl Session {
     }
 }
 
-#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Encodable, Decodable)]
-#[derive(HashStable_Generic)]
-pub enum NativeLibKind {
-    /// Static library (e.g. `libfoo.a` on Linux or `foo.lib` on Windows/MSVC)
-    Static {
-        /// Whether to bundle objects from static library into produced rlib
-        bundle: Option<bool>,
-        /// Whether to link static library without throwing any object files away
-        whole_archive: Option<bool>,
-    },
-    /// Dynamic library (e.g. `libfoo.so` on Linux)
-    /// or an import library corresponding to a dynamic library (e.g. `foo.lib` on Windows/MSVC).
-    Dylib {
-        /// Whether the dynamic library will be linked only if it satisfies some undefined symbols
-        as_needed: Option<bool>,
-    },
-    /// Dynamic library (e.g. `foo.dll` on Windows) without a corresponding import library.
-    /// On Linux, it refers to a generated shared library stub.
-    RawDylib,
-    /// A macOS-specific kind of dynamic libraries.
-    Framework {
-        /// Whether the framework will be linked only if it satisfies some undefined symbols
-        as_needed: Option<bool>,
-    },
-    /// Argument which is passed to linker, relative order with libraries and other arguments
-    /// is preserved
-    LinkArg,
-
-    /// Module imported from WebAssembly
-    WasmImportModule,
-
-    /// The library kind wasn't specified, `Dylib` is currently used as a default.
-    Unspecified,
-}
-
-impl NativeLibKind {
-    pub fn has_modifiers(&self) -> bool {
-        match self {
-            NativeLibKind::Static { bundle, whole_archive } => {
-                bundle.is_some() || whole_archive.is_some()
-            }
-            NativeLibKind::Dylib { as_needed } | NativeLibKind::Framework { as_needed } => {
-                as_needed.is_some()
-            }
-            NativeLibKind::RawDylib
-            | NativeLibKind::Unspecified
-            | NativeLibKind::LinkArg
-            | NativeLibKind::WasmImportModule => false,
-        }
-    }
-
-    pub fn is_statically_included(&self) -> bool {
-        matches!(self, NativeLibKind::Static { .. })
-    }
-
-    pub fn is_dllimport(&self) -> bool {
-        matches!(
-            self,
-            NativeLibKind::Dylib { .. } | NativeLibKind::RawDylib | NativeLibKind::Unspecified
-        )
-    }
-}
-
 #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Encodable, Decodable)]
 #[derive(HashStable_Generic)]
 pub struct NativeLib {
diff --git a/compiler/rustc_span/Cargo.toml b/compiler/rustc_span/Cargo.toml
index 43a2d692577..2e45177e3b7 100644
--- a/compiler/rustc_span/Cargo.toml
+++ b/compiler/rustc_span/Cargo.toml
@@ -19,6 +19,6 @@ rustc_serialize = { path = "../rustc_serialize" }
 scoped-tls = "1.0"
 sha1 = "0.10.0"
 sha2 = "0.10.1"
-tracing = "0.1"
+tracing.workspace = true
 unicode-width = "0.2.0"
 # tidy-alphabetical-end
diff --git a/compiler/rustc_span/src/caching_source_map_view.rs b/compiler/rustc_span/src/caching_source_map_view.rs
index a887b50ec1e..41cfaa3ee34 100644
--- a/compiler/rustc_span/src/caching_source_map_view.rs
+++ b/compiler/rustc_span/src/caching_source_map_view.rs
@@ -123,27 +123,25 @@ impl<'sm> CachingSourceMapView<'sm> {
 
         if lo_cache_idx != -1 && hi_cache_idx != -1 {
             // Cache hit for span lo and hi. Check if they belong to the same file.
-            let result = {
-                let lo = &self.line_cache[lo_cache_idx as usize];
-                let hi = &self.line_cache[hi_cache_idx as usize];
+            let lo_file_index = self.line_cache[lo_cache_idx as usize].file_index;
+            let hi_file_index = self.line_cache[hi_cache_idx as usize].file_index;
 
-                if lo.file_index != hi.file_index {
-                    return None;
-                }
-
-                (
-                    lo.file.stable_id,
-                    lo.line_number,
-                    span_data.lo - lo.line.start,
-                    hi.line_number,
-                    span_data.hi - hi.line.start,
-                )
-            };
+            if lo_file_index != hi_file_index {
+                return None;
+            }
 
             self.line_cache[lo_cache_idx as usize].touch(self.time_stamp);
             self.line_cache[hi_cache_idx as usize].touch(self.time_stamp);
 
-            return Some(result);
+            let lo = &self.line_cache[lo_cache_idx as usize];
+            let hi = &self.line_cache[hi_cache_idx as usize];
+            return Some((
+                lo.file.stable_id,
+                lo.line_number,
+                span_data.lo - lo.line.start,
+                hi.line_number,
+                span_data.hi - hi.line.start,
+            ));
         }
 
         // No cache hit or cache hit for only one of span lo and hi.
diff --git a/compiler/rustc_span/src/source_map.rs b/compiler/rustc_span/src/source_map.rs
index d9315149798..166842e374b 100644
--- a/compiler/rustc_span/src/source_map.rs
+++ b/compiler/rustc_span/src/source_map.rs
@@ -9,6 +9,7 @@
 //! within the `SourceMap`, which upon request can be converted to line and column
 //! information, source code snippets, etc.
 
+use std::fs::File;
 use std::io::{self, BorrowedBuf, Read};
 use std::{fs, path};
 
@@ -115,13 +116,18 @@ impl FileLoader for RealFileLoader {
     }
 
     fn read_file(&self, path: &Path) -> io::Result<String> {
-        if path.metadata().is_ok_and(|metadata| metadata.len() > SourceFile::MAX_FILE_SIZE.into()) {
+        let mut file = File::open(path)?;
+        let size = file.metadata().map(|metadata| metadata.len()).ok().unwrap_or(0);
+
+        if size > SourceFile::MAX_FILE_SIZE.into() {
             return Err(io::Error::other(format!(
                 "text files larger than {} bytes are unsupported",
                 SourceFile::MAX_FILE_SIZE
             )));
         }
-        fs::read_to_string(path)
+        let mut contents = String::new();
+        file.read_to_string(&mut contents)?;
+        Ok(contents)
     }
 
     fn read_binary_file(&self, path: &Path) -> io::Result<Arc<[u8]>> {
@@ -911,12 +917,13 @@ impl SourceMap {
 
     /// Returns a new span representing just the last character of this span.
     pub fn end_point(&self, sp: Span) -> Span {
-        let pos = sp.hi().0;
+        let sp = sp.data();
+        let pos = sp.hi.0;
 
         let width = self.find_width_of_character_at_span(sp, false);
         let corrected_end_position = pos.checked_sub(width).unwrap_or(pos);
 
-        let end_point = BytePos(cmp::max(corrected_end_position, sp.lo().0));
+        let end_point = BytePos(cmp::max(corrected_end_position, sp.lo.0));
         sp.with_lo(end_point)
     }
 
@@ -930,8 +937,9 @@ impl SourceMap {
         if sp.is_dummy() {
             return sp;
         }
-        let start_of_next_point = sp.hi().0;
 
+        let sp = sp.data();
+        let start_of_next_point = sp.hi.0;
         let width = self.find_width_of_character_at_span(sp, true);
         // If the width is 1, then the next span should only contain the next char besides current ending.
         // However, in the case of a multibyte character, where the width != 1, the next span should
@@ -940,7 +948,7 @@ impl SourceMap {
             start_of_next_point.checked_add(width).unwrap_or(start_of_next_point);
 
         let end_of_next_point = BytePos(cmp::max(start_of_next_point + 1, end_of_next_point));
-        Span::new(BytePos(start_of_next_point), end_of_next_point, sp.ctxt(), None)
+        Span::new(BytePos(start_of_next_point), end_of_next_point, sp.ctxt, None)
     }
 
     /// Check whether span is followed by some specified expected string in limit scope
@@ -963,9 +971,7 @@ impl SourceMap {
     /// Finds the width of the character, either before or after the end of provided span,
     /// depending on the `forwards` parameter.
     #[instrument(skip(self, sp))]
-    fn find_width_of_character_at_span(&self, sp: Span, forwards: bool) -> u32 {
-        let sp = sp.data();
-
+    fn find_width_of_character_at_span(&self, sp: SpanData, forwards: bool) -> u32 {
         if sp.lo == sp.hi && !forwards {
             debug!("early return empty span");
             return 1;
diff --git a/compiler/rustc_span/src/span_encoding.rs b/compiler/rustc_span/src/span_encoding.rs
index a4a47dc99b0..e34efa784de 100644
--- a/compiler/rustc_span/src/span_encoding.rs
+++ b/compiler/rustc_span/src/span_encoding.rs
@@ -74,9 +74,8 @@ use crate::{BytePos, SPAN_TRACK, SpanData};
 ///   because `parent` isn't currently used by default.
 ///
 /// In order to reliably use parented spans in incremental compilation,
-/// the dependency to the parent definition's span. This is performed
-/// using the callback `SPAN_TRACK` to access the query engine.
-///
+/// accesses to `lo` and `hi` must introduce a dependency to the parent definition's span.
+/// This is performed using the callback `SPAN_TRACK` to access the query engine.
 #[derive(Clone, Copy, Eq, PartialEq, Hash)]
 #[rustc_pass_by_value]
 pub struct Span {
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index acbed7a9eed..77260d07c99 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -392,6 +392,7 @@ symbols! {
         __D,
         __H,
         __S,
+        __T,
         __awaitee,
         __try_var,
         _t,
@@ -446,6 +447,7 @@ symbols! {
         altivec,
         alu32,
         always,
+        analysis,
         and,
         and_then,
         anon,
@@ -464,6 +466,7 @@ symbols! {
         arm,
         arm_target_feature,
         array,
+        as_dash_needed: "as-needed",
         as_ptr,
         as_ref,
         as_str,
@@ -538,13 +541,16 @@ symbols! {
         att_syntax,
         attr,
         attr_literals,
+        attribute,
         attributes,
         audit_that,
         augmented_assignments,
         auto_traits,
+        autodiff,
         autodiff_forward,
         autodiff_reverse,
         automatically_derived,
+        available_externally,
         avx,
         avx10_target_feature,
         avx512_target_feature,
@@ -586,7 +592,9 @@ symbols! {
         btreemap_contains_key,
         btreemap_insert,
         btreeset_iter,
+        built,
         builtin_syntax,
+        bundle,
         c,
         c_dash_variadic,
         c_str,
@@ -676,6 +684,7 @@ symbols! {
         cold_path,
         collapse_debuginfo,
         column,
+        common,
         compare_bytes,
         compare_exchange,
         compare_exchange_weak,
@@ -743,6 +752,7 @@ symbols! {
         contracts_ensures,
         contracts_internals,
         contracts_requires,
+        convert,
         convert_identity,
         copy,
         copy_closures,
@@ -810,6 +820,7 @@ symbols! {
         decl_macro,
         declare_lint_pass,
         decode,
+        decorated,
         default_alloc_error_handler,
         default_field_values,
         default_fn,
@@ -844,11 +855,13 @@ symbols! {
         derive_const,
         derive_const_issue: "118304",
         derive_default_enum,
+        derive_from,
         derive_smart_pointer,
         destruct,
         destructuring_assignment,
         diagnostic,
         diagnostic_namespace,
+        dialect,
         direct,
         discriminant_kind,
         discriminant_type,
@@ -892,6 +905,7 @@ symbols! {
         dynamic_no_pic: "dynamic-no-pic",
         e,
         edition_panic,
+        effective_target_features,
         effects,
         eh_catch_typeinfo,
         eh_personality,
@@ -956,6 +970,7 @@ symbols! {
         extern_prelude,
         extern_system_varargs,
         extern_types,
+        extern_weak,
         external,
         external_doc,
         f,
@@ -1051,6 +1066,7 @@ symbols! {
         fn_ptr_addr,
         fn_ptr_trait,
         forbid,
+        force_target_feature,
         forget,
         format,
         format_args,
@@ -1063,6 +1079,7 @@ symbols! {
         format_macro,
         format_placeholder,
         format_unsafe_arg,
+        framework,
         freeze,
         freeze_impls,
         freg,
@@ -1204,6 +1221,7 @@ symbols! {
         infer_static_outlives_requirements,
         inherent_associated_types,
         inherit,
+        initial,
         inlateout,
         inline,
         inline_const,
@@ -1213,6 +1231,7 @@ symbols! {
         instruction_set,
         integer_: "integer", // underscore to avoid clashing with the function `sym::integer` below
         integral,
+        internal,
         internal_features,
         into_async_iter_into_iter,
         into_future,
@@ -1249,6 +1268,7 @@ symbols! {
         iterator,
         iterator_collect_fn,
         kcfi,
+        kernel_address,
         keylocker_x86,
         keyword,
         kind,
@@ -1280,6 +1300,7 @@ symbols! {
         link_arg_attribute,
         link_args,
         link_cfg,
+        link_dash_arg: "link-arg",
         link_llvm_intrinsics,
         link_name,
         link_ordinal,
@@ -1287,6 +1308,8 @@ symbols! {
         linkage,
         linker,
         linker_messages,
+        linkonce,
+        linkonce_odr,
         lint_reasons,
         literal,
         load,
@@ -1315,6 +1338,7 @@ symbols! {
         macro_attr,
         macro_attributes_in_derive_output,
         macro_concat,
+        macro_derive,
         macro_escape,
         macro_export,
         macro_lifetime_matcher,
@@ -1510,6 +1534,7 @@ symbols! {
         noop_method_borrow,
         noop_method_clone,
         noop_method_deref,
+        noprefix,
         noreturn,
         nostack,
         not,
@@ -1536,6 +1561,7 @@ symbols! {
         opt_out_copy,
         optimize,
         optimize_attribute,
+        optimized,
         optin_builtin_traits,
         option,
         option_env,
@@ -1583,6 +1609,7 @@ symbols! {
         panic_const_shl_overflow,
         panic_const_shr_overflow,
         panic_const_sub_overflow,
+        panic_display,
         panic_fmt,
         panic_handler,
         panic_impl,
@@ -1617,6 +1644,7 @@ symbols! {
         pattern_types,
         permissions_from_mode,
         phantom_data,
+        phase,
         pic,
         pie,
         pin,
@@ -1633,6 +1661,7 @@ symbols! {
         poll,
         poll_next,
         position,
+        post_cleanup: "post-cleanup",
         post_dash_lto: "post-lto",
         postfix_match,
         powerpc_target_feature,
@@ -1719,6 +1748,7 @@ symbols! {
         quote,
         range_inclusive_new,
         range_step,
+        raw_dash_dylib: "raw-dylib",
         raw_dylib,
         raw_dylib_elf,
         raw_eq,
@@ -1734,6 +1764,7 @@ symbols! {
         readonly,
         realloc,
         reason,
+        reborrow,
         receiver,
         receiver_target,
         recursion_limit,
@@ -1796,6 +1827,7 @@ symbols! {
         roundf128,
         rt,
         rtm_target_feature,
+        runtime,
         rust,
         rust_2015,
         rust_2018,
@@ -1816,6 +1848,7 @@ symbols! {
         rustc_align,
         rustc_allocator,
         rustc_allocator_zeroed,
+        rustc_allocator_zeroed_variant,
         rustc_allow_const_fn_unstable,
         rustc_allow_incoherent_impl,
         rustc_allowed_through_unstable_modules,
@@ -1828,7 +1861,6 @@ symbols! {
         rustc_coherence_is_core,
         rustc_coinductive,
         rustc_confusables,
-        rustc_const_panic_str,
         rustc_const_stable,
         rustc_const_stable_indirect,
         rustc_const_unstable,
@@ -2253,6 +2285,7 @@ symbols! {
         unchecked_shl,
         unchecked_shr,
         unchecked_sub,
+        undecorated,
         underscore_const_names,
         underscore_imports,
         underscore_lifetimes,
@@ -2324,6 +2357,7 @@ symbols! {
         va_start,
         val,
         validity,
+        value,
         values,
         var,
         variant_count,
@@ -2340,6 +2374,7 @@ symbols! {
         vecdeque_iter,
         vecdeque_reserve,
         vector,
+        verbatim,
         version,
         vfp2,
         vis,
@@ -2360,8 +2395,11 @@ symbols! {
         wasm_abi,
         wasm_import_module,
         wasm_target_feature,
+        weak,
+        weak_odr,
         where_clause_attrs,
         while_let,
+        whole_dash_archive: "whole-archive",
         width,
         windows,
         windows_subsystem,
@@ -2392,9 +2430,11 @@ symbols! {
         yield_expr,
         ymm_reg,
         yreg,
+        zca,
         zfh,
         zfhmin,
         zmm_reg,
+        ztso,
         // tidy-alphabetical-end
     }
 }
@@ -2509,10 +2549,16 @@ impl fmt::Debug for Ident {
 /// except that AST identifiers don't keep the rawness flag, so we have to guess it.
 impl fmt::Display for Ident {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt::Display::fmt(&IdentPrinter::new(self.name, self.is_raw_guess(), None), f)
+        fmt::Display::fmt(&IdentPrinter::new(self.name, self.guess_print_mode(), None), f)
     }
 }
 
+pub enum IdentPrintMode {
+    Normal,
+    RawIdent,
+    RawLifetime,
+}
+
 /// The most general type to print identifiers.
 ///
 /// AST pretty-printer is used as a fallback for turning AST structures into token streams for
@@ -2528,7 +2574,7 @@ impl fmt::Display for Ident {
 /// done for a token stream or a single token.
 pub struct IdentPrinter {
     symbol: Symbol,
-    is_raw: bool,
+    mode: IdentPrintMode,
     /// Span used for retrieving the crate name to which `$crate` refers to,
     /// if this field is `None` then the `$crate` conversion doesn't happen.
     convert_dollar_crate: Option<Span>,
@@ -2536,32 +2582,51 @@ pub struct IdentPrinter {
 
 impl IdentPrinter {
     /// The most general `IdentPrinter` constructor. Do not use this.
-    pub fn new(symbol: Symbol, is_raw: bool, convert_dollar_crate: Option<Span>) -> IdentPrinter {
-        IdentPrinter { symbol, is_raw, convert_dollar_crate }
+    pub fn new(
+        symbol: Symbol,
+        mode: IdentPrintMode,
+        convert_dollar_crate: Option<Span>,
+    ) -> IdentPrinter {
+        IdentPrinter { symbol, mode, convert_dollar_crate }
     }
 
     /// This implementation is supposed to be used when printing identifiers
     /// as a part of pretty-printing for larger AST pieces.
     /// Do not use this either.
-    pub fn for_ast_ident(ident: Ident, is_raw: bool) -> IdentPrinter {
-        IdentPrinter::new(ident.name, is_raw, Some(ident.span))
+    pub fn for_ast_ident(ident: Ident, mode: IdentPrintMode) -> IdentPrinter {
+        IdentPrinter::new(ident.name, mode, Some(ident.span))
     }
 }
 
 impl fmt::Display for IdentPrinter {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        if self.is_raw {
-            f.write_str("r#")?;
-        } else if self.symbol == kw::DollarCrate {
-            if let Some(span) = self.convert_dollar_crate {
+        let s = match self.mode {
+            IdentPrintMode::Normal
+                if self.symbol == kw::DollarCrate
+                    && let Some(span) = self.convert_dollar_crate =>
+            {
                 let converted = span.ctxt().dollar_crate_name();
                 if !converted.is_path_segment_keyword() {
                     f.write_str("::")?;
                 }
-                return fmt::Display::fmt(&converted, f);
+                converted
             }
-        }
-        fmt::Display::fmt(&self.symbol, f)
+            IdentPrintMode::Normal => self.symbol,
+            IdentPrintMode::RawIdent => {
+                f.write_str("r#")?;
+                self.symbol
+            }
+            IdentPrintMode::RawLifetime => {
+                f.write_str("'r#")?;
+                let s = self
+                    .symbol
+                    .as_str()
+                    .strip_prefix("'")
+                    .expect("only lifetime idents should be passed with RawLifetime mode");
+                Symbol::intern(s)
+            }
+        };
+        s.fmt(f)
     }
 }
 
@@ -2996,6 +3061,29 @@ impl Ident {
         self.name.can_be_raw() && self.is_reserved()
     }
 
+    /// Given the name of a lifetime without the first quote (`'`),
+    /// returns whether the lifetime name is reserved (therefore invalid)
+    pub fn is_reserved_lifetime(self) -> bool {
+        self.is_reserved() && ![kw::Underscore, kw::Static].contains(&self.name)
+    }
+
+    pub fn is_raw_lifetime_guess(self) -> bool {
+        let name_without_apostrophe = self.without_first_quote();
+        name_without_apostrophe.name != self.name
+            && name_without_apostrophe.name.can_be_raw()
+            && name_without_apostrophe.is_reserved_lifetime()
+    }
+
+    pub fn guess_print_mode(self) -> IdentPrintMode {
+        if self.is_raw_lifetime_guess() {
+            IdentPrintMode::RawLifetime
+        } else if self.is_raw_guess() {
+            IdentPrintMode::RawIdent
+        } else {
+            IdentPrintMode::Normal
+        }
+    }
+
     /// Whether this would be the identifier for a tuple field like `self.0`, as
     /// opposed to a named field like `self.thing`.
     pub fn is_numeric(self) -> bool {
diff --git a/compiler/rustc_symbol_mangling/Cargo.toml b/compiler/rustc_symbol_mangling/Cargo.toml
index 0df9c7682bf..48e02dabdde 100644
--- a/compiler/rustc_symbol_mangling/Cargo.toml
+++ b/compiler/rustc_symbol_mangling/Cargo.toml
@@ -15,5 +15,5 @@ rustc_hir = { path = "../rustc_hir" }
 rustc_middle = { path = "../rustc_middle" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_symbol_mangling/src/legacy.rs b/compiler/rustc_symbol_mangling/src/legacy.rs
index a7f64085bd9..4d9741f1d11 100644
--- a/compiler/rustc_symbol_mangling/src/legacy.rs
+++ b/compiler/rustc_symbol_mangling/src/legacy.rs
@@ -58,7 +58,7 @@ pub(super) fn mangle<'tcx>(
 
     let hash = get_symbol_hash(tcx, instance, instance_ty, instantiating_crate);
 
-    let mut p = SymbolPrinter { tcx, path: SymbolPath::new(), keep_within_component: false };
+    let mut p = LegacySymbolMangler { tcx, path: SymbolPath::new(), keep_within_component: false };
     p.print_def_path(
         def_id,
         if let ty::InstanceKind::DropGlue(_, _)
@@ -213,13 +213,13 @@ impl SymbolPath {
     }
 }
 
-struct SymbolPrinter<'tcx> {
+struct LegacySymbolMangler<'tcx> {
     tcx: TyCtxt<'tcx>,
     path: SymbolPath,
 
     // When `true`, `finalize_pending_component` isn't used.
-    // This is needed when recursing into `path_qualified`,
-    // or `path_generic_args`, as any nested paths are
+    // This is needed when recursing into `print_path_with_qualified`,
+    // or `print_path_with_generic_args`, as any nested paths are
     // logically within one component.
     keep_within_component: bool,
 }
@@ -228,14 +228,15 @@ struct SymbolPrinter<'tcx> {
 // `PrettyPrinter` aka pretty printing of e.g. types in paths,
 // symbol names should have their own printing machinery.
 
-impl<'tcx> Printer<'tcx> for SymbolPrinter<'tcx> {
+impl<'tcx> Printer<'tcx> for LegacySymbolMangler<'tcx> {
     fn tcx(&self) -> TyCtxt<'tcx> {
         self.tcx
     }
 
     fn print_region(&mut self, _region: ty::Region<'_>) -> Result<(), PrintError> {
         // This might be reachable (via `pretty_print_dyn_existential`) even though
-        // `<Self As PrettyPrinter>::should_print_region` returns false. See #144994.
+        // `<Self As PrettyPrinter>::should_print_optional_region` returns false and
+        // `print_path_with_generic_args` filters out lifetimes. See #144994.
         Ok(())
     }
 
@@ -305,16 +306,17 @@ impl<'tcx> Printer<'tcx> for SymbolPrinter<'tcx> {
         Ok(())
     }
 
-    fn path_crate(&mut self, cnum: CrateNum) -> Result<(), PrintError> {
+    fn print_crate_name(&mut self, cnum: CrateNum) -> Result<(), PrintError> {
         self.write_str(self.tcx.crate_name(cnum).as_str())?;
         Ok(())
     }
-    fn path_qualified(
+
+    fn print_path_with_qualified(
         &mut self,
         self_ty: Ty<'tcx>,
         trait_ref: Option<ty::TraitRef<'tcx>>,
     ) -> Result<(), PrintError> {
-        // Similar to `pretty_path_qualified`, but for the other
+        // Similar to `pretty_print_path_with_qualified`, but for the other
         // types that are printed as paths (see `print_type` above).
         match self_ty.kind() {
             ty::FnDef(..)
@@ -327,17 +329,17 @@ impl<'tcx> Printer<'tcx> for SymbolPrinter<'tcx> {
                 self.print_type(self_ty)
             }
 
-            _ => self.pretty_path_qualified(self_ty, trait_ref),
+            _ => self.pretty_print_path_with_qualified(self_ty, trait_ref),
         }
     }
 
-    fn path_append_impl(
+    fn print_path_with_impl(
         &mut self,
         print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
         self_ty: Ty<'tcx>,
         trait_ref: Option<ty::TraitRef<'tcx>>,
     ) -> Result<(), PrintError> {
-        self.pretty_path_append_impl(
+        self.pretty_print_path_with_impl(
             |cx| {
                 print_prefix(cx)?;
 
@@ -354,7 +356,8 @@ impl<'tcx> Printer<'tcx> for SymbolPrinter<'tcx> {
             trait_ref,
         )
     }
-    fn path_append(
+
+    fn print_path_with_simple(
         &mut self,
         print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
         disambiguated_data: &DisambiguatedDefPathData,
@@ -377,7 +380,8 @@ impl<'tcx> Printer<'tcx> for SymbolPrinter<'tcx> {
 
         Ok(())
     }
-    fn path_generic_args(
+
+    fn print_path_with_generic_args(
         &mut self,
         print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
         args: &[GenericArg<'tcx>],
@@ -386,7 +390,6 @@ impl<'tcx> Printer<'tcx> for SymbolPrinter<'tcx> {
 
         let args =
             args.iter().cloned().filter(|arg| !matches!(arg.kind(), GenericArgKind::Lifetime(_)));
-
         if args.clone().next().is_some() {
             self.generic_delimiters(|cx| cx.comma_sep(args))
         } else {
@@ -455,8 +458,8 @@ impl<'tcx> Printer<'tcx> for SymbolPrinter<'tcx> {
     }
 }
 
-impl<'tcx> PrettyPrinter<'tcx> for SymbolPrinter<'tcx> {
-    fn should_print_region(&self, _region: ty::Region<'_>) -> bool {
+impl<'tcx> PrettyPrinter<'tcx> for LegacySymbolMangler<'tcx> {
+    fn should_print_optional_region(&self, _region: ty::Region<'_>) -> bool {
         false
     }
 
@@ -491,7 +494,7 @@ impl<'tcx> PrettyPrinter<'tcx> for SymbolPrinter<'tcx> {
     }
 }
 
-impl fmt::Write for SymbolPrinter<'_> {
+impl fmt::Write for LegacySymbolMangler<'_> {
     fn write_str(&mut self, s: &str) -> fmt::Result {
         // Name sanitation. LLVM will happily accept identifiers with weird names, but
         // gas doesn't!
diff --git a/compiler/rustc_symbol_mangling/src/lib.rs b/compiler/rustc_symbol_mangling/src/lib.rs
index 6bcb7f6e093..d97ee956525 100644
--- a/compiler/rustc_symbol_mangling/src/lib.rs
+++ b/compiler/rustc_symbol_mangling/src/lib.rs
@@ -193,67 +193,54 @@ fn compute_symbol_name<'tcx>(
         // defining crate.
         // Weak lang items automatically get #[rustc_std_internal_symbol]
         // applied by the code computing the CodegenFnAttrs.
-        // We are mangling all #[rustc_std_internal_symbol] items that don't
-        // also have #[no_mangle] as a combination of the rustc version and the
-        // unmangled linkage name. This is to ensure that if we link against a
-        // staticlib compiled by a different rustc version, we don't get symbol
-        // conflicts or even UB due to a different implementation/ABI. Rust
-        // staticlibs currently export all symbols, including those that are
-        // hidden in cdylibs.
+        // We are mangling all #[rustc_std_internal_symbol] items as a
+        // combination of the rustc version and the unmangled linkage name.
+        // This is to ensure that if we link against a staticlib compiled by a
+        // different rustc version, we don't get symbol conflicts or even UB
+        // due to a different implementation/ABI. Rust staticlibs currently
+        // export all symbols, including those that are hidden in cdylibs.
         // We are using the v0 symbol mangling scheme here as we need to be
         // consistent across all crates and in some contexts the legacy symbol
         // mangling scheme can't be used. For example both the GCC backend and
         // Rust-for-Linux don't support some of the characters used by the
         // legacy symbol mangling scheme.
-        let name = if tcx.is_foreign_item(def_id) {
-            if let Some(name) = attrs.link_name { name } else { tcx.item_name(def_id) }
-        } else {
-            if let Some(name) = attrs.export_name { name } else { tcx.item_name(def_id) }
-        };
+        let name = if let Some(name) = attrs.symbol_name { name } else { tcx.item_name(def_id) };
 
-        if attrs.flags.contains(CodegenFnAttrFlags::NO_MANGLE) {
-            return name.to_string();
-        } else {
-            return v0::mangle_internal_symbol(tcx, name.as_str());
-        }
+        return v0::mangle_internal_symbol(tcx, name.as_str());
     }
 
-    // Foreign items by default use no mangling for their symbol name. There's a
-    // few exceptions to this rule though:
-    //
-    // * This can be overridden with the `#[link_name]` attribute
-    //
-    // * On the wasm32 targets there is a bug (or feature) in LLD [1] where the
-    //   same-named symbol when imported from different wasm modules will get
-    //   hooked up incorrectly. As a result foreign symbols, on the wasm target,
-    //   with a wasm import module, get mangled. Additionally our codegen will
-    //   deduplicate symbols based purely on the symbol name, but for wasm this
-    //   isn't quite right because the same-named symbol on wasm can come from
-    //   different modules. For these reasons if `#[link(wasm_import_module)]`
-    //   is present we mangle everything on wasm because the demangled form will
-    //   show up in the `wasm-import-name` custom attribute in LLVM IR.
-    //
-    // * `#[rustc_std_internal_symbol]` mangles the symbol name in a special way
-    //   both for exports and imports through foreign items. This is handled above.
-    // [1]: https://bugs.llvm.org/show_bug.cgi?id=44316
-    if tcx.is_foreign_item(def_id)
-        && (!tcx.sess.target.is_like_wasm
-            || !tcx.wasm_import_module_map(def_id.krate).contains_key(&def_id))
-    {
-        if let Some(name) = attrs.link_name {
+    let wasm_import_module_exception_force_mangling = {
+        // * On the wasm32 targets there is a bug (or feature) in LLD [1] where the
+        //   same-named symbol when imported from different wasm modules will get
+        //   hooked up incorrectly. As a result foreign symbols, on the wasm target,
+        //   with a wasm import module, get mangled. Additionally our codegen will
+        //   deduplicate symbols based purely on the symbol name, but for wasm this
+        //   isn't quite right because the same-named symbol on wasm can come from
+        //   different modules. For these reasons if `#[link(wasm_import_module)]`
+        //   is present we mangle everything on wasm because the demangled form will
+        //   show up in the `wasm-import-name` custom attribute in LLVM IR.
+        //
+        // [1]: https://bugs.llvm.org/show_bug.cgi?id=44316
+        //
+        // So, on wasm if a foreign item loses its `#[no_mangle]`, it might *still*
+        // be mangled if we're forced to. Note: I don't like this.
+        // These kinds of exceptions should be added during the `codegen_attrs` query.
+        // However, we don't have the wasm import module map there yet.
+        tcx.is_foreign_item(def_id)
+            && tcx.sess.target.is_like_wasm
+            && tcx.wasm_import_module_map(LOCAL_CRATE).contains_key(&def_id.into())
+    };
+
+    if !wasm_import_module_exception_force_mangling {
+        if let Some(name) = attrs.symbol_name {
+            // Use provided name
             return name.to_string();
         }
-        return tcx.item_name(def_id).to_string();
-    }
-
-    if let Some(name) = attrs.export_name {
-        // Use provided name
-        return name.to_string();
-    }
 
-    if attrs.flags.contains(CodegenFnAttrFlags::NO_MANGLE) {
-        // Don't mangle
-        return tcx.item_name(def_id).to_string();
+        if attrs.flags.contains(CodegenFnAttrFlags::NO_MANGLE) {
+            // Don't mangle
+            return tcx.item_name(def_id).to_string();
+        }
     }
 
     // If we're dealing with an instance of a function that's inlined from
diff --git a/compiler/rustc_symbol_mangling/src/v0.rs b/compiler/rustc_symbol_mangling/src/v0.rs
index c2458ae814b..0cbd48ba08c 100644
--- a/compiler/rustc_symbol_mangling/src/v0.rs
+++ b/compiler/rustc_symbol_mangling/src/v0.rs
@@ -33,7 +33,7 @@ pub(super) fn mangle<'tcx>(
     let args = tcx.normalize_erasing_regions(ty::TypingEnv::fully_monomorphized(), instance.args);
 
     let prefix = "_R";
-    let mut p: SymbolMangler<'_> = SymbolMangler {
+    let mut p: V0SymbolMangler<'_> = V0SymbolMangler {
         tcx,
         start_offset: prefix.len(),
         is_exportable,
@@ -88,7 +88,7 @@ pub fn mangle_internal_symbol<'tcx>(tcx: TyCtxt<'tcx>, item_name: &str) -> Strin
     }
 
     let prefix = "_R";
-    let mut p: SymbolMangler<'_> = SymbolMangler {
+    let mut p: V0SymbolMangler<'_> = V0SymbolMangler {
         tcx,
         start_offset: prefix.len(),
         is_exportable: false,
@@ -131,7 +131,7 @@ pub(super) fn mangle_typeid_for_trait_ref<'tcx>(
     trait_ref: ty::ExistentialTraitRef<'tcx>,
 ) -> String {
     // FIXME(flip1995): See comment in `mangle_typeid_for_fnabi`.
-    let mut p = SymbolMangler {
+    let mut p = V0SymbolMangler {
         tcx,
         start_offset: 0,
         is_exportable: false,
@@ -159,7 +159,7 @@ struct BinderLevel {
     lifetime_depths: Range<u32>,
 }
 
-struct SymbolMangler<'tcx> {
+struct V0SymbolMangler<'tcx> {
     tcx: TyCtxt<'tcx>,
     binders: Vec<BinderLevel>,
     out: String,
@@ -173,7 +173,7 @@ struct SymbolMangler<'tcx> {
     consts: FxHashMap<ty::Const<'tcx>, usize>,
 }
 
-impl<'tcx> SymbolMangler<'tcx> {
+impl<'tcx> V0SymbolMangler<'tcx> {
     fn push(&mut self, s: &str) {
         self.out.push_str(s);
     }
@@ -272,7 +272,7 @@ impl<'tcx> SymbolMangler<'tcx> {
     }
 }
 
-impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
+impl<'tcx> Printer<'tcx> for V0SymbolMangler<'tcx> {
     fn tcx(&self) -> TyCtxt<'tcx> {
         self.tcx
     }
@@ -365,7 +365,7 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
         // Encode impl generic params if the generic parameters contain non-region parameters
         // and this isn't an inherent impl.
         if impl_trait_ref.is_some() && args.iter().any(|a| a.has_non_region_param()) {
-            self.path_generic_args(
+            self.print_path_with_generic_args(
                 |this| {
                     this.path_append_ns(
                         |p| p.print_def_path(parent_def_id, &[]),
@@ -786,7 +786,7 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
                             None => {
                                 self.push("S");
                                 for (field_def, field) in iter::zip(&variant_def.fields, fields) {
-                                    // HACK(eddyb) this mimics `path_append`,
+                                    // HACK(eddyb) this mimics `print_path_with_simple`,
                                     // instead of simply using `field_def.ident`,
                                     // just to be able to handle disambiguators.
                                     let disambiguated_field =
@@ -819,7 +819,7 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
         Ok(())
     }
 
-    fn path_crate(&mut self, cnum: CrateNum) -> Result<(), PrintError> {
+    fn print_crate_name(&mut self, cnum: CrateNum) -> Result<(), PrintError> {
         self.push("C");
         if !self.is_exportable {
             let stable_crate_id = self.tcx.def_path_hash(cnum.as_def_id()).stable_crate_id();
@@ -830,7 +830,7 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
         Ok(())
     }
 
-    fn path_qualified(
+    fn print_path_with_qualified(
         &mut self,
         self_ty: Ty<'tcx>,
         trait_ref: Option<ty::TraitRef<'tcx>>,
@@ -843,7 +843,7 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
         self.print_def_path(trait_ref.def_id, trait_ref.args)
     }
 
-    fn path_append_impl(
+    fn print_path_with_impl(
         &mut self,
         _: impl FnOnce(&mut Self) -> Result<(), PrintError>,
         _: Ty<'tcx>,
@@ -853,7 +853,7 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
         unreachable!()
     }
 
-    fn path_append(
+    fn print_path_with_simple(
         &mut self,
         print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
         disambiguated_data: &DisambiguatedDefPathData,
@@ -873,7 +873,7 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
             DefPathData::SyntheticCoroutineBody => 's',
             DefPathData::NestedStatic => 'n',
 
-            // These should never show up as `path_append` arguments.
+            // These should never show up as `print_path_with_simple` arguments.
             DefPathData::CrateRoot
             | DefPathData::Use
             | DefPathData::GlobalAsm
@@ -896,7 +896,7 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
         )
     }
 
-    fn path_generic_args(
+    fn print_path_with_generic_args(
         &mut self,
         print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
         args: &[GenericArg<'tcx>],
diff --git a/compiler/rustc_target/Cargo.toml b/compiler/rustc_target/Cargo.toml
index 56932c24922..3c257bf38a5 100644
--- a/compiler/rustc_target/Cargo.toml
+++ b/compiler/rustc_target/Cargo.toml
@@ -5,9 +5,11 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-bitflags = "2.4.1"
+bitflags.workspace = true
+object = { version = "0.37.0", default-features = false, features = ["elf", "macho"] }
 rustc_abi = { path = "../rustc_abi" }
 rustc_data_structures = { path = "../rustc_data_structures" }
+rustc_error_messages = { path = "../rustc_error_messages" }
 rustc_fs_util = { path = "../rustc_fs_util" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }
@@ -16,12 +18,6 @@ serde = "1.0.219"
 serde_derive = "1.0.219"
 serde_json = "1.0.59"
 serde_path_to_error = "0.1.17"
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
 
-[dependencies.object]
-# tidy-alphabetical-start
-default-features = false
-features = ["elf", "macho"]
-version = "0.37.0"
-# tidy-alphabetical-end
diff --git a/compiler/rustc_target/src/callconv/mod.rs b/compiler/rustc_target/src/callconv/mod.rs
index 63e56744aec..7a7c63c475b 100644
--- a/compiler/rustc_target/src/callconv/mod.rs
+++ b/compiler/rustc_target/src/callconv/mod.rs
@@ -114,11 +114,12 @@ mod attr_impl {
     bitflags::bitflags! {
         impl ArgAttribute: u8 {
             const NoAlias   = 1 << 1;
-            const NoCapture = 1 << 2;
+            const CapturesAddress = 1 << 2;
             const NonNull   = 1 << 3;
             const ReadOnly  = 1 << 4;
             const InReg     = 1 << 5;
             const NoUndef = 1 << 6;
+            const CapturesReadOnly = 1 << 7;
         }
     }
     rustc_data_structures::external_bitflags_debug! { ArgAttribute }
@@ -399,11 +400,11 @@ impl<'a, Ty> ArgAbi<'a, Ty> {
         let mut attrs = ArgAttributes::new();
 
         // For non-immediate arguments the callee gets its own copy of
-        // the value on the stack, so there are no aliases. It's also
-        // program-invisible so can't possibly capture
+        // the value on the stack, so there are no aliases. The function
+        // can capture the address of the argument, but not the provenance.
         attrs
             .set(ArgAttribute::NoAlias)
-            .set(ArgAttribute::NoCapture)
+            .set(ArgAttribute::CapturesAddress)
             .set(ArgAttribute::NonNull)
             .set(ArgAttribute::NoUndef);
         attrs.pointee_size = layout.size;
diff --git a/compiler/rustc_target/src/spec/json.rs b/compiler/rustc_target/src/spec/json.rs
index 6c44b7ff52f..f56a65d9c0c 100644
--- a/compiler/rustc_target/src/spec/json.rs
+++ b/compiler/rustc_target/src/spec/json.rs
@@ -168,7 +168,6 @@ impl Target {
         forward!(main_needs_argc_argv);
         forward!(has_thread_local);
         forward!(obj_is_bitcode);
-        forward!(bitcode_llvm_cmdline);
         forward_opt!(max_atomic_width);
         forward_opt!(min_atomic_width);
         forward!(atomic_cas);
@@ -361,7 +360,6 @@ impl ToJson for Target {
         target_option_val!(main_needs_argc_argv);
         target_option_val!(has_thread_local);
         target_option_val!(obj_is_bitcode);
-        target_option_val!(bitcode_llvm_cmdline);
         target_option_val!(min_atomic_width);
         target_option_val!(max_atomic_width);
         target_option_val!(atomic_cas);
@@ -555,7 +553,6 @@ struct TargetSpecJson {
     main_needs_argc_argv: Option<bool>,
     has_thread_local: Option<bool>,
     obj_is_bitcode: Option<bool>,
-    bitcode_llvm_cmdline: Option<StaticCow<str>>,
     max_atomic_width: Option<u64>,
     min_atomic_width: Option<u64>,
     atomic_cas: Option<bool>,
diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs
index b9fbff8db05..c53d92bee9d 100644
--- a/compiler/rustc_target/src/spec/mod.rs
+++ b/compiler/rustc_target/src/spec/mod.rs
@@ -50,6 +50,7 @@ use rustc_abi::{
     Align, CanonAbi, Endian, ExternAbi, Integer, Size, TargetDataLayout, TargetDataLayoutErrors,
 };
 use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
+use rustc_error_messages::{DiagArgValue, IntoDiagArg, into_diag_arg_using_display};
 use rustc_fs_util::try_canonicalize;
 use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
@@ -875,6 +876,12 @@ impl FromStr for PanicStrategy {
 
 crate::json::serde_deserialize_from_str!(PanicStrategy);
 
+impl IntoDiagArg for PanicStrategy {
+    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+        DiagArgValue::Str(Cow::Owned(self.desc().to_string()))
+    }
+}
+
 impl ToJson for PanicStrategy {
     fn to_json(&self) -> Json {
         match *self {
@@ -1518,6 +1525,8 @@ impl fmt::Display for SplitDebuginfo {
     }
 }
 
+into_diag_arg_using_display!(SplitDebuginfo);
+
 #[derive(Clone, Debug, PartialEq, Eq, serde_derive::Deserialize)]
 #[serde(tag = "kind")]
 #[serde(rename_all = "kebab-case")]
@@ -1795,6 +1804,8 @@ impl fmt::Display for StackProtector {
     }
 }
 
+into_diag_arg_using_display!(StackProtector);
+
 #[derive(PartialEq, Clone, Debug)]
 pub enum BinaryFormat {
     Coff,
@@ -1943,6 +1954,7 @@ supported_targets! {
     ("armv7-unknown-linux-musleabihf", armv7_unknown_linux_musleabihf),
     ("aarch64-unknown-linux-gnu", aarch64_unknown_linux_gnu),
     ("aarch64-unknown-linux-musl", aarch64_unknown_linux_musl),
+    ("aarch64_be-unknown-linux-musl", aarch64_be_unknown_linux_musl),
     ("x86_64-unknown-linux-musl", x86_64_unknown_linux_musl),
     ("i686-unknown-linux-musl", i686_unknown_linux_musl),
     ("i586-unknown-linux-musl", i586_unknown_linux_musl),
@@ -2105,6 +2117,7 @@ supported_targets! {
 
     ("msp430-none-elf", msp430_none_elf),
 
+    ("aarch64_be-unknown-hermit", aarch64_be_unknown_hermit),
     ("aarch64-unknown-hermit", aarch64_unknown_hermit),
     ("riscv64gc-unknown-hermit", riscv64gc_unknown_hermit),
     ("x86_64-unknown-hermit", x86_64_unknown_hermit),
@@ -2137,6 +2150,7 @@ supported_targets! {
     ("riscv64gc-unknown-none-elf", riscv64gc_unknown_none_elf),
     ("riscv64gc-unknown-linux-gnu", riscv64gc_unknown_linux_gnu),
     ("riscv64gc-unknown-linux-musl", riscv64gc_unknown_linux_musl),
+    ("riscv64a23-unknown-linux-gnu", riscv64a23_unknown_linux_gnu),
 
     ("sparc-unknown-none-elf", sparc_unknown_none_elf),
 
@@ -2147,6 +2161,7 @@ supported_targets! {
 
     ("aarch64-unknown-none", aarch64_unknown_none),
     ("aarch64-unknown-none-softfloat", aarch64_unknown_none_softfloat),
+    ("aarch64_be-unknown-none-softfloat", aarch64_be_unknown_none_softfloat),
     ("aarch64-unknown-nuttx", aarch64_unknown_nuttx),
 
     ("x86_64-fortanix-unknown-sgx", x86_64_fortanix_unknown_sgx),
@@ -2623,8 +2638,6 @@ pub struct TargetOptions {
     /// If we give emcc .o files that are actually .bc files it
     /// will 'just work'.
     pub obj_is_bitcode: bool,
-    /// Content of the LLVM cmdline section associated with embedded bitcode.
-    pub bitcode_llvm_cmdline: StaticCow<str>,
 
     /// Don't use this field; instead use the `.min_atomic_width()` method.
     pub min_atomic_width: Option<u64>,
@@ -2988,7 +3001,6 @@ impl Default for TargetOptions {
             allow_asm: true,
             has_thread_local: false,
             obj_is_bitcode: false,
-            bitcode_llvm_cmdline: "".into(),
             min_atomic_width: None,
             max_atomic_width: None,
             atomic_cas: true,
@@ -3808,3 +3820,5 @@ impl fmt::Display for TargetTuple {
         write!(f, "{}", self.debug_tuple())
     }
 }
+
+into_diag_arg_using_display!(&TargetTuple);
diff --git a/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_hermit.rs b/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_hermit.rs
new file mode 100644
index 00000000000..cad57abc2b1
--- /dev/null
+++ b/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_hermit.rs
@@ -0,0 +1,25 @@
+use rustc_abi::Endian;
+
+use crate::spec::{StackProbeType, Target, TargetMetadata, TargetOptions, base};
+
+pub(crate) fn target() -> Target {
+    Target {
+        llvm_target: "aarch64_be-unknown-hermit".into(),
+        metadata: TargetMetadata {
+            description: Some("ARM64 Hermit (big-endian)".into()),
+            tier: Some(3),
+            host_tools: Some(false),
+            std: Some(true),
+        },
+        pointer_width: 64,
+        arch: "aarch64".into(),
+        data_layout: "E-m:e-p270:32:32-p271:32:32-p272:64:64-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32".into(),
+        options: TargetOptions {
+            features: "+v8a,+strict-align,+neon,+fp-armv8".into(),
+            max_atomic_width: Some(128),
+            stack_probes: StackProbeType::Inline,
+            endian: Endian::Big,
+            ..base::hermit::opts()
+        },
+    }
+}
diff --git a/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_linux_musl.rs b/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_linux_musl.rs
new file mode 100644
index 00000000000..be5ac4a843b
--- /dev/null
+++ b/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_linux_musl.rs
@@ -0,0 +1,40 @@
+use rustc_abi::Endian;
+
+use crate::spec::{
+    FramePointer, SanitizerSet, StackProbeType, Target, TargetMetadata, TargetOptions, base,
+};
+
+pub(crate) fn target() -> Target {
+    let mut base = base::linux_musl::opts();
+    base.max_atomic_width = Some(128);
+    base.supports_xray = true;
+    base.features = "+v8a,+outline-atomics".into();
+    base.stack_probes = StackProbeType::Inline;
+    base.supported_sanitizers = SanitizerSet::ADDRESS
+        | SanitizerSet::CFI
+        | SanitizerSet::LEAK
+        | SanitizerSet::MEMORY
+        | SanitizerSet::THREAD;
+
+    Target {
+        llvm_target: "aarch64_be-unknown-linux-musl".into(),
+        metadata: TargetMetadata {
+            description: Some("ARM64 Linux (big-endian) with musl-libc 1.2.5".into()),
+            tier: Some(3),
+            host_tools: Some(false),
+            std: Some(true),
+        },
+        pointer_width: 64,
+        data_layout: "E-m:e-p270:32:32-p271:32:32-p272:64:64-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32".into(),
+        arch: "aarch64".into(),
+        options: TargetOptions {
+            // the AAPCS64 expects use of non-leaf frame pointers per
+            // https://github.com/ARM-software/abi-aa/blob/4492d1570eb70c8fd146623e0db65b2d241f12e7/aapcs64/aapcs64.rst#the-frame-pointer
+            // and we tend to encounter interesting bugs in AArch64 unwinding code if we do not
+            frame_pointer: FramePointer::NonLeaf,
+            mcount: "\u{1}_mcount".into(),
+            endian: Endian::Big,
+            ..base
+        },
+    }
+}
diff --git a/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_none_softfloat.rs b/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_none_softfloat.rs
new file mode 100644
index 00000000000..7f918e85080
--- /dev/null
+++ b/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_none_softfloat.rs
@@ -0,0 +1,43 @@
+// Generic big-endian AArch64 target for bare-metal code - Floating point disabled
+//
+// Can be used in conjunction with the `target-feature` and
+// `target-cpu` compiler flags to opt-in more hardware-specific
+// features.
+//
+// For example, `-C target-cpu=cortex-a53`.
+use rustc_abi::Endian;
+
+use crate::spec::{
+    Cc, LinkerFlavor, Lld, PanicStrategy, RelocModel, SanitizerSet, StackProbeType, Target,
+    TargetMetadata, TargetOptions,
+};
+
+pub(crate) fn target() -> Target {
+    let opts = TargetOptions {
+        abi: "softfloat".into(),
+        linker_flavor: LinkerFlavor::Gnu(Cc::No, Lld::Yes),
+        linker: Some("rust-lld".into()),
+        features: "+v8a,+strict-align,-neon,-fp-armv8".into(),
+        relocation_model: RelocModel::Static,
+        disable_redzone: true,
+        max_atomic_width: Some(128),
+        supported_sanitizers: SanitizerSet::KCFI | SanitizerSet::KERNELADDRESS,
+        stack_probes: StackProbeType::Inline,
+        panic_strategy: PanicStrategy::Abort,
+        endian: Endian::Big,
+        ..Default::default()
+    };
+    Target {
+        llvm_target: "aarch64_be-unknown-none".into(),
+        metadata: TargetMetadata {
+            description: Some("Bare ARM64 (big-endian), softfloat".into()),
+            tier: Some(3),
+            host_tools: Some(false),
+            std: Some(false),
+        },
+        pointer_width: 64,
+        data_layout: "E-m:e-p270:32:32-p271:32:32-p272:64:64-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32".into(),
+        arch: "aarch64".into(),
+        options: opts,
+    }
+}
diff --git a/compiler/rustc_target/src/spec/targets/aarch64_nintendo_switch_freestanding.rs b/compiler/rustc_target/src/spec/targets/aarch64_nintendo_switch_freestanding.rs
index 9b81362b27d..61e4cad3fa2 100644
--- a/compiler/rustc_target/src/spec/targets/aarch64_nintendo_switch_freestanding.rs
+++ b/compiler/rustc_target/src/spec/targets/aarch64_nintendo_switch_freestanding.rs
@@ -19,7 +19,7 @@ pub(crate) fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32".into(),
         arch: "aarch64".into(),
         options: TargetOptions {
-            features: "+v8a".into(),
+            features: "+v8a,+neon,+crypto,+crc".into(),
             linker_flavor: LinkerFlavor::Gnu(Cc::No, Lld::Yes),
             linker: Some("rust-lld".into()),
             link_script: Some(LINKER_SCRIPT.into()),
diff --git a/compiler/rustc_target/src/spec/targets/armv7a_vex_v5_linker_script.ld b/compiler/rustc_target/src/spec/targets/armv7a_vex_v5_linker_script.ld
index a4783de0183..0f3e6eeee19 100644
--- a/compiler/rustc_target/src/spec/targets/armv7a_vex_v5_linker_script.ld
+++ b/compiler/rustc_target/src/spec/targets/armv7a_vex_v5_linker_script.ld
@@ -17,15 +17,25 @@ PROVIDE(__vcodesig_type = 0);               /* V5_SIG_TYPE_USER     */
 PROVIDE(__vcodesig_owner = 2);              /* V5_SIG_OWNER_PARTNER */
 PROVIDE(__vcodesig_options = 0);            /* none (0)             */
 
-PROVIDE(__user_ram_start = 0x03800000);
-PROVIDE(__user_ram_length = 48M);
-PROVIDE(__user_ram_end = __user_ram_start + __user_ram_length); /* 0x8000000 */
+__user_ram_start = 0x03800000;
+__user_ram_end   = 0x08000000;
+/* (0x48 =) 72 MiB length */
+__user_ram_length = __user_ram_start - __user_ram_end;
 
-PROVIDE(__code_signature_length = 0x20);
+/*
+ * VEXos provides a method for pre-loading a "linked file" at a specified
+ * address in User RAM, conventionally near the end, after the primary
+ * program binary. We need to be sure not to place any data in that location,
+ * so we allow the user of this linker script to inform the start address of
+ * this blob.
+ */
+PROVIDE(__linked_file_length = 0);
+PROVIDE(__linked_file_end = __user_ram_end);
+PROVIDE(__linked_file_start = __linked_file_end - __linked_file_length);
 
 PROVIDE(__stack_length = 4M);
-PROVIDE(__heap_end = __user_ram_end - __stack_length);
-PROVIDE(__user_length = __heap_start - __user_ram_start);
+PROVIDE(__stack_top = __linked_file_start);
+PROVIDE(__stack_bottom = __linked_file_start - __stack_length);
 
 MEMORY {
     USER_RAM (RWX) : ORIGIN = __user_ram_start, LENGTH = __user_ram_length
@@ -44,7 +54,7 @@ SECTIONS {
         LONG(__vcodesig_options)
 
         FILL(0)
-        . = __user_ram_start + __code_signature_length;
+        . = __user_ram_start + 0x20;
     } > USER_RAM
 
     /*
@@ -125,7 +135,8 @@ SECTIONS {
      */
     .heap (NOLOAD) : {
         __heap_start = .;
-        . = __heap_end;
+        . = __stack_bottom;
+        __heap_end = .;
     } > USER_RAM
 
     .stack (NOLOAD) : ALIGN(8) {
diff --git a/compiler/rustc_target/src/spec/targets/avr_none.rs b/compiler/rustc_target/src/spec/targets/avr_none.rs
index 07ed2a37803..ad056d02326 100644
--- a/compiler/rustc_target/src/spec/targets/avr_none.rs
+++ b/compiler/rustc_target/src/spec/targets/avr_none.rs
@@ -9,7 +9,7 @@ pub(crate) fn target() -> Target {
             host_tools: None,
             std: None,
         },
-        data_layout: "e-P1-p:16:8-i8:8-i16:8-i32:8-i64:8-f32:8-f64:8-n8-a:8".into(),
+        data_layout: "e-P1-p:16:8-i8:8-i16:8-i32:8-i64:8-f32:8-f64:8-n8:16-a:8".into(),
         llvm_target: "avr-unknown-unknown".into(),
         pointer_width: 16,
         options: TargetOptions {
diff --git a/compiler/rustc_target/src/spec/targets/riscv64a23_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/targets/riscv64a23_unknown_linux_gnu.rs
new file mode 100644
index 00000000000..60f2e7da042
--- /dev/null
+++ b/compiler/rustc_target/src/spec/targets/riscv64a23_unknown_linux_gnu.rs
@@ -0,0 +1,27 @@
+use std::borrow::Cow;
+
+use crate::spec::{CodeModel, SplitDebuginfo, Target, TargetMetadata, TargetOptions, base};
+
+pub(crate) fn target() -> Target {
+    Target {
+        llvm_target: "riscv64-unknown-linux-gnu".into(),
+        metadata: TargetMetadata {
+            description: Some("RISC-V Linux (kernel 6.8.0, glibc 2.39)".into()),
+            tier: Some(3),
+            host_tools: Some(true),
+            std: Some(true),
+        },
+        pointer_width: 64,
+        data_layout: "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128".into(),
+        arch: "riscv64".into(),
+        options: TargetOptions {
+            code_model: Some(CodeModel::Medium),
+            cpu: "generic-rv64".into(),
+            features: "+rva23u64".into(),
+            llvm_abiname: "lp64d".into(),
+            max_atomic_width: Some(64),
+            supported_split_debuginfo: Cow::Borrowed(&[SplitDebuginfo::Off]),
+            ..base::linux_gnu::opts()
+        },
+    }
+}
diff --git a/compiler/rustc_target/src/spec/targets/x86_64_apple_darwin.rs b/compiler/rustc_target/src/spec/targets/x86_64_apple_darwin.rs
index 53e2cb469ee..8892c50d844 100644
--- a/compiler/rustc_target/src/spec/targets/x86_64_apple_darwin.rs
+++ b/compiler/rustc_target/src/spec/targets/x86_64_apple_darwin.rs
@@ -7,7 +7,7 @@ pub(crate) fn target() -> Target {
         llvm_target,
         metadata: TargetMetadata {
             description: Some("x86_64 Apple macOS (10.12+, Sierra+)".into()),
-            tier: Some(1),
+            tier: Some(2),
             host_tools: Some(true),
             std: Some(true),
         },
diff --git a/compiler/rustc_target/src/target_features.rs b/compiler/rustc_target/src/target_features.rs
index 297d9ed84c5..4c1b8c99426 100644
--- a/compiler/rustc_target/src/target_features.rs
+++ b/compiler/rustc_target/src/target_features.rs
@@ -248,6 +248,10 @@ static AARCH64_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     ("mte", Stable, &[]),
     // FEAT_AdvSimd & FEAT_FP
     ("neon", Stable, &[]),
+    // Backend option to turn atomic operations into an intrinsic call when `lse` is not known to be
+    // available, so the intrinsic can do runtime LSE feature detection rather than unconditionally
+    // using slower non-LSE operations. Unstable since it doesn't need to user-togglable.
+    ("outline-atomics", Unstable(sym::aarch64_unstable_target_feature), &[]),
     // FEAT_PAUTH (address authentication)
     ("paca", Stable, &[]),
     // FEAT_PAUTH (generic authentication)
@@ -471,9 +475,9 @@ static X86_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     ("sse3", Stable, &["sse2"]),
     ("sse4.1", Stable, &["ssse3"]),
     ("sse4.2", Stable, &["sse4.1"]),
-    ("sse4a", Unstable(sym::sse4a_target_feature), &["sse3"]),
+    ("sse4a", Stable, &["sse3"]),
     ("ssse3", Stable, &["sse3"]),
-    ("tbm", Unstable(sym::tbm_target_feature), &[]),
+    ("tbm", Stable, &[]),
     ("vaes", Stable, &["avx2", "aes"]),
     ("vpclmulqdq", Stable, &["avx", "pclmulqdq"]),
     ("widekl", Stable, &["kl"]),
@@ -597,6 +601,49 @@ static RISCV_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     ),
     ("m", Stable, &[]),
     ("relax", Unstable(sym::riscv_target_feature), &[]),
+    (
+        "rva23u64",
+        Unstable(sym::riscv_target_feature),
+        &[
+            "m",
+            "a",
+            "f",
+            "d",
+            "c",
+            "b",
+            "v",
+            "zicsr",
+            "zicntr",
+            "zihpm",
+            "ziccif",
+            "ziccrse",
+            "ziccamoa",
+            "zicclsm",
+            "zic64b",
+            "za64rs",
+            "zihintpause",
+            "zba",
+            "zbb",
+            "zbs",
+            "zicbom",
+            "zicbop",
+            "zicboz",
+            "zfhmin",
+            "zkt",
+            "zvfhmin",
+            "zvbb",
+            "zvkt",
+            "zihintntl",
+            "zicond",
+            "zimop",
+            "zcmop",
+            "zcb",
+            "zfa",
+            "zawrs",
+            "supm",
+        ],
+    ),
+    ("supm", Unstable(sym::riscv_target_feature), &[]),
     ("unaligned-scalar-mem", Unstable(sym::riscv_target_feature), &[]),
     ("unaligned-vector-mem", Unstable(sym::riscv_target_feature), &[]),
     ("v", Unstable(sym::riscv_target_feature), &["zvl128b", "zve64d"]),
@@ -763,6 +810,7 @@ static CSKY_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
 
 static LOONGARCH_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     // tidy-alphabetical-start
+    ("32s", Unstable(sym::loongarch_target_feature), &[]),
     ("d", Stable, &["f"]),
     ("div32", Unstable(sym::loongarch_target_feature), &[]),
     ("f", Stable, &[]),
diff --git a/compiler/rustc_thread_pool/src/lib.rs b/compiler/rustc_thread_pool/src/lib.rs
index 34252d919e3..7ce7fbc27ea 100644
--- a/compiler/rustc_thread_pool/src/lib.rs
+++ b/compiler/rustc_thread_pool/src/lib.rs
@@ -787,18 +787,7 @@ impl ThreadPoolBuildError {
     }
 }
 
-const GLOBAL_POOL_ALREADY_INITIALIZED: &str =
-    "The global thread pool has already been initialized.";
-
 impl Error for ThreadPoolBuildError {
-    #[allow(deprecated)]
-    fn description(&self) -> &str {
-        match self.kind {
-            ErrorKind::GlobalPoolAlreadyInitialized => GLOBAL_POOL_ALREADY_INITIALIZED,
-            ErrorKind::IOError(ref e) => e.description(),
-        }
-    }
-
     fn source(&self) -> Option<&(dyn Error + 'static)> {
         match &self.kind {
             ErrorKind::GlobalPoolAlreadyInitialized => None,
@@ -810,7 +799,9 @@ impl Error for ThreadPoolBuildError {
 impl fmt::Display for ThreadPoolBuildError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match &self.kind {
-            ErrorKind::GlobalPoolAlreadyInitialized => GLOBAL_POOL_ALREADY_INITIALIZED.fmt(f),
+            ErrorKind::GlobalPoolAlreadyInitialized => {
+                "The global thread pool has already been initialized.".fmt(f)
+            }
             ErrorKind::IOError(e) => e.fmt(f),
         }
     }
diff --git a/compiler/rustc_trait_selection/Cargo.toml b/compiler/rustc_trait_selection/Cargo.toml
index 1071105522d..6b79b98d1bf 100644
--- a/compiler/rustc_trait_selection/Cargo.toml
+++ b/compiler/rustc_trait_selection/Cargo.toml
@@ -5,7 +5,7 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-itertools = "0.12"
+itertools.workspace = true
 rustc_abi = { path = "../rustc_abi" }
 rustc_ast = { path = "../rustc_ast" }
 rustc_data_structures = { path = "../rustc_data_structures" }
@@ -21,6 +21,6 @@ rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_transmute = { path = "../rustc_transmute", features = ["rustc"] }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
-thin-vec = "0.2"
-tracing = "0.1"
+thin-vec.workspace = true
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs b/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs
index 8551780bcd5..9447612d026 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs
@@ -224,41 +224,41 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         use ty::GenericArg;
         use ty::print::Printer;
 
-        struct AbsolutePathPrinter<'tcx> {
+        struct ConflictingPathPrinter<'tcx> {
             tcx: TyCtxt<'tcx>,
             segments: Vec<Symbol>,
         }
 
-        impl<'tcx> Printer<'tcx> for AbsolutePathPrinter<'tcx> {
+        impl<'tcx> Printer<'tcx> for ConflictingPathPrinter<'tcx> {
             fn tcx<'a>(&'a self) -> TyCtxt<'tcx> {
                 self.tcx
             }
 
             fn print_region(&mut self, _region: ty::Region<'_>) -> Result<(), PrintError> {
-                unreachable!(); // because `path_generic_args` ignores the `GenericArgs`
+                unreachable!(); // because `print_path_with_generic_args` ignores the `GenericArgs`
             }
 
             fn print_type(&mut self, _ty: Ty<'tcx>) -> Result<(), PrintError> {
-                unreachable!(); // because `path_generic_args` ignores the `GenericArgs`
+                unreachable!(); // because `print_path_with_generic_args` ignores the `GenericArgs`
             }
 
             fn print_dyn_existential(
                 &mut self,
                 _predicates: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
             ) -> Result<(), PrintError> {
-                unreachable!(); // because `path_generic_args` ignores the `GenericArgs`
+                unreachable!(); // because `print_path_with_generic_args` ignores the `GenericArgs`
             }
 
             fn print_const(&mut self, _ct: ty::Const<'tcx>) -> Result<(), PrintError> {
-                unreachable!(); // because `path_generic_args` ignores the `GenericArgs`
+                unreachable!(); // because `print_path_with_generic_args` ignores the `GenericArgs`
             }
 
-            fn path_crate(&mut self, cnum: CrateNum) -> Result<(), PrintError> {
+            fn print_crate_name(&mut self, cnum: CrateNum) -> Result<(), PrintError> {
                 self.segments = vec![self.tcx.crate_name(cnum)];
                 Ok(())
             }
 
-            fn path_qualified(
+            fn print_path_with_qualified(
                 &mut self,
                 _self_ty: Ty<'tcx>,
                 _trait_ref: Option<ty::TraitRef<'tcx>>,
@@ -266,7 +266,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                 Err(fmt::Error)
             }
 
-            fn path_append_impl(
+            fn print_path_with_impl(
                 &mut self,
                 _print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
                 _self_ty: Ty<'tcx>,
@@ -275,7 +275,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                 Err(fmt::Error)
             }
 
-            fn path_append(
+            fn print_path_with_simple(
                 &mut self,
                 print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
                 disambiguated_data: &DisambiguatedDefPathData,
@@ -285,7 +285,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                 Ok(())
             }
 
-            fn path_generic_args(
+            fn print_path_with_generic_args(
                 &mut self,
                 print_prefix: impl FnOnce(&mut Self) -> Result<(), PrintError>,
                 _args: &[GenericArg<'tcx>],
@@ -300,28 +300,27 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
             // let _ = [{struct Foo; Foo}, {struct Foo; Foo}];
             if did1.krate != did2.krate {
                 let abs_path = |def_id| {
-                    let mut p = AbsolutePathPrinter { tcx: self.tcx, segments: vec![] };
+                    let mut p = ConflictingPathPrinter { tcx: self.tcx, segments: vec![] };
                     p.print_def_path(def_id, &[]).map(|_| p.segments)
                 };
 
-                // We compare strings because DefPath can be different
-                // for imported and non-imported crates
+                // We compare strings because DefPath can be different for imported and
+                // non-imported crates.
                 let expected_str = self.tcx.def_path_str(did1);
                 let found_str = self.tcx.def_path_str(did2);
                 let Ok(expected_abs) = abs_path(did1) else { return false };
                 let Ok(found_abs) = abs_path(did2) else { return false };
-                let same_path = || -> Result<_, PrintError> {
-                    Ok(expected_str == found_str || expected_abs == found_abs)
-                };
-                // We want to use as unique a type path as possible. If both types are "locally
-                // known" by the same name, we use the "absolute path" which uses the original
-                // crate name instead.
-                let (expected, found) = if expected_str == found_str {
-                    (join_path_syms(&expected_abs), join_path_syms(&found_abs))
-                } else {
-                    (expected_str.clone(), found_str.clone())
-                };
-                if same_path().unwrap_or(false) {
+                let same_path = expected_str == found_str || expected_abs == found_abs;
+                if same_path {
+                    // We want to use as unique a type path as possible. If both types are "locally
+                    // known" by the same name, we use the "absolute path" which uses the original
+                    // crate name instead.
+                    let (expected, found) = if expected_str == found_str {
+                        (join_path_syms(&expected_abs), join_path_syms(&found_abs))
+                    } else {
+                        (expected_str.clone(), found_str.clone())
+                    };
+
                     // We've displayed "expected `a::b`, found `a::b`". We add context to
                     // differentiate the different cases where that might happen.
                     let expected_crate_name = self.tcx.crate_name(did1.krate);
@@ -1620,8 +1619,18 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         {
             let e = self.tcx.erase_regions(e);
             let f = self.tcx.erase_regions(f);
-            let expected = with_forced_trimmed_paths!(e.sort_string(self.tcx));
-            let found = with_forced_trimmed_paths!(f.sort_string(self.tcx));
+            let mut expected = with_forced_trimmed_paths!(e.sort_string(self.tcx));
+            let mut found = with_forced_trimmed_paths!(f.sort_string(self.tcx));
+            if let ObligationCauseCode::Pattern { span, .. } = cause.code()
+                && let Some(span) = span
+                && !span.from_expansion()
+                && cause.span.from_expansion()
+            {
+                // When the type error comes from a macro like `assert!()`, and we are pointing at
+                // code the user wrote the cause and effect are reversed as the expected value is
+                // what the macro expanded to.
+                (found, expected) = (expected, found);
+            }
             if expected == found {
                 label_or_note(span, terr.to_string(self.tcx));
             } else {
@@ -2144,7 +2153,9 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
     ) -> Option<(DiagStyledString, DiagStyledString)> {
         match values {
             ValuePairs::Regions(exp_found) => self.expected_found_str(exp_found),
-            ValuePairs::Terms(exp_found) => self.expected_found_str_term(exp_found, long_ty_path),
+            ValuePairs::Terms(exp_found) => {
+                self.expected_found_str_term(cause, exp_found, long_ty_path)
+            }
             ValuePairs::Aliases(exp_found) => self.expected_found_str(exp_found),
             ValuePairs::ExistentialTraitRef(exp_found) => self.expected_found_str(exp_found),
             ValuePairs::ExistentialProjection(exp_found) => self.expected_found_str(exp_found),
@@ -2183,6 +2194,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
 
     fn expected_found_str_term(
         &self,
+        cause: &ObligationCause<'tcx>,
         exp_found: ty::error::ExpectedFound<ty::Term<'tcx>>,
         long_ty_path: &mut Option<PathBuf>,
     ) -> Option<(DiagStyledString, DiagStyledString)> {
@@ -2190,8 +2202,27 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         if exp_found.references_error() {
             return None;
         }
+        let (mut expected, mut found) = (exp_found.expected, exp_found.found);
+
+        if let ObligationCauseCode::Pattern { span, .. } = cause.code()
+            && let Some(span) = span
+            && !span.from_expansion()
+            && cause.span.from_expansion()
+        {
+            // When the type error comes from a macro like `assert!()`, and we are pointing at
+            // code the user wrote, the cause and effect are reversed as the expected value is
+            // what the macro expanded to. So if the user provided a `Type` when the macro is
+            // written in such a way that a `bool` was expected, we want to print:
+            // = note: expected `bool`
+            //            found `Type`"
+            // but as far as the compiler is concerned, after expansion what was expected was `Type`
+            // = note: expected `Type`
+            //            found `bool`"
+            // so we reverse them here to match user expectation.
+            (expected, found) = (found, expected);
+        }
 
-        Some(match (exp_found.expected.kind(), exp_found.found.kind()) {
+        Some(match (expected.kind(), found.kind()) {
             (ty::TermKind::Ty(expected), ty::TermKind::Ty(found)) => {
                 let (mut exp, mut fnd) = self.cmp(expected, found);
                 // Use the terminal width as the basis to determine when to compress the printed
diff --git a/compiler/rustc_trait_selection/src/error_reporting/infer/note_and_explain.rs b/compiler/rustc_trait_selection/src/error_reporting/infer/note_and_explain.rs
index 8f0f6d0bf26..40285e5d0e9 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/infer/note_and_explain.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/infer/note_and_explain.rs
@@ -537,7 +537,7 @@ impl<T> Trait<T> for X {
                 }
             }
             TypeError::TargetFeatureCast(def_id) => {
-                let target_spans = find_attr!(tcx.get_all_attrs(def_id), AttributeKind::TargetFeature(.., span) => *span);
+                let target_spans = find_attr!(tcx.get_all_attrs(def_id), AttributeKind::TargetFeature{attr_span: span, was_forced: false, ..} => *span);
                 diag.note(
                     "functions with `#[target_feature]` can only be coerced to `unsafe` function pointers"
                 );
@@ -946,7 +946,7 @@ fn foo(&self) -> Self::T { String::new() }
 
     pub fn format_generic_args(&self, args: &[ty::GenericArg<'tcx>]) -> String {
         FmtPrinter::print_string(self.tcx, hir::def::Namespace::TypeNS, |p| {
-            p.path_generic_args(|_| Ok(()), args)
+            p.print_path_with_generic_args(|_| Ok(()), args)
         })
         .expect("could not write to `String`.")
     }
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
index 62859329de3..d768e0bf63f 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
@@ -37,7 +37,6 @@ use super::on_unimplemented::{AppendConstMessage, OnUnimplementedNote};
 use super::suggestions::get_explanation_based_on_obligation;
 use super::{
     ArgKind, CandidateSimilarity, FindExprBySpan, GetSafeTransmuteErrorAndReason, ImplCandidate,
-    UnsatisfiedConst,
 };
 use crate::error_reporting::TypeErrCtxt;
 use crate::error_reporting::infer::TyCategory;
@@ -276,8 +275,9 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                         *err.long_ty_path() = long_ty_file;
 
                         let mut suggested = false;
+                        let mut noted_missing_impl = false;
                         if is_try_conversion || is_question_mark {
-                            suggested = self.try_conversion_context(&obligation, main_trait_predicate, &mut err);
+                            (suggested, noted_missing_impl) = self.try_conversion_context(&obligation, main_trait_predicate, &mut err);
                         }
 
                         if let Some(ret_span) = self.return_type_span(&obligation) {
@@ -336,6 +336,11 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                             return err.emit();
                         }
 
+                        let ty_span = match leaf_trait_predicate.self_ty().skip_binder().kind() {
+                            ty::Adt(def, _) if def.did().is_local()
+                                && !self.can_suggest_derive(&obligation, leaf_trait_predicate) => self.tcx.def_span(def.did()),
+                            _ => DUMMY_SP,
+                        };
                         if let Some(s) = label {
                             // If it has a custom `#[rustc_on_unimplemented]`
                             // error message, let's display it as the label!
@@ -348,15 +353,28 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                                     // Don't say "the trait `FromResidual<Option<Infallible>>` is
                                     // not implemented for `Result<T, E>`".
                             {
-                                err.help(explanation);
+                                // We do this just so that the JSON output's `help` position is the
+                                // right one and not `file.rs:1:1`. The render is the same.
+                                if ty_span == DUMMY_SP {
+                                    err.help(explanation);
+                                } else {
+                                    err.span_help(ty_span, explanation);
+                                }
                             }
                         } else if let Some(custom_explanation) = safe_transmute_explanation {
                             err.span_label(span, custom_explanation);
-                        } else if explanation.len() > self.tcx.sess.diagnostic_width() {
+                        } else if (explanation.len() > self.tcx.sess.diagnostic_width() || ty_span != DUMMY_SP) && !noted_missing_impl {
                             // Really long types don't look good as span labels, instead move it
                             // to a `help`.
                             err.span_label(span, "unsatisfied trait bound");
-                            err.help(explanation);
+
+                            // We do this just so that the JSON output's `help` position is the
+                            // right one and not `file.rs:1:1`. The render is the same.
+                            if ty_span == DUMMY_SP {
+                                err.help(explanation);
+                            } else {
+                                err.span_help(ty_span, explanation);
+                            }
                         } else {
                             err.span_label(span, explanation);
                         }
@@ -374,13 +392,6 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                             }
                         }
 
-                        let UnsatisfiedConst(unsatisfied_const) = self
-                            .maybe_add_note_for_unsatisfied_const(
-                                leaf_trait_predicate,
-                                &mut err,
-                                span,
-                            );
-
                         if let Some((msg, span)) = type_def {
                             err.span_label(span, msg);
                         }
@@ -506,7 +517,6 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                             span,
                             is_fn_trait,
                             suggested,
-                            unsatisfied_const,
                         );
 
                         // Changing mutability doesn't make a difference to whether we have
@@ -948,7 +958,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         obligation: &PredicateObligation<'tcx>,
         trait_pred: ty::PolyTraitPredicate<'tcx>,
         err: &mut Diag<'_>,
-    ) -> bool {
+    ) -> (bool, bool) {
         let span = obligation.cause.span;
         /// Look for the (direct) sub-expr of `?`, and return it if it's a `.` method call.
         struct FindMethodSubexprOfTry {
@@ -968,21 +978,22 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
             }
         }
         let hir_id = self.tcx.local_def_id_to_hir_id(obligation.cause.body_id);
-        let Some(body_id) = self.tcx.hir_node(hir_id).body_id() else { return false };
+        let Some(body_id) = self.tcx.hir_node(hir_id).body_id() else { return (false, false) };
         let ControlFlow::Break(expr) =
             (FindMethodSubexprOfTry { search_span: span }).visit_body(self.tcx.hir_body(body_id))
         else {
-            return false;
+            return (false, false);
         };
         let Some(typeck) = &self.typeck_results else {
-            return false;
+            return (false, false);
         };
         let ObligationCauseCode::QuestionMark = obligation.cause.code().peel_derives() else {
-            return false;
+            return (false, false);
         };
         let self_ty = trait_pred.skip_binder().self_ty();
         let found_ty = trait_pred.skip_binder().trait_ref.args.get(1).and_then(|a| a.as_type());
-        self.note_missing_impl_for_question_mark(err, self_ty, found_ty, trait_pred);
+        let noted_missing_impl =
+            self.note_missing_impl_for_question_mark(err, self_ty, found_ty, trait_pred);
 
         let mut prev_ty = self.resolve_vars_if_possible(
             typeck.expr_ty_adjusted_opt(expr).unwrap_or(Ty::new_misc_error(self.tcx)),
@@ -1146,7 +1157,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
             }
             prev = Some(err_ty);
         }
-        suggested
+        (suggested, noted_missing_impl)
     }
 
     fn note_missing_impl_for_question_mark(
@@ -1155,7 +1166,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         self_ty: Ty<'_>,
         found_ty: Option<Ty<'_>>,
         trait_pred: ty::PolyTraitPredicate<'tcx>,
-    ) {
+    ) -> bool {
         match (self_ty.kind(), found_ty) {
             (ty::Adt(def, _), Some(ty))
                 if let ty::Adt(found, _) = ty.kind()
@@ -1196,8 +1207,9 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                     format!("`{ty}` needs to implement `Into<{self_ty}>`"),
                 );
             }
-            _ => {}
+            _ => return false,
         }
+        true
     }
 
     fn report_const_param_not_wf(
@@ -2716,7 +2728,6 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         span: Span,
         is_fn_trait: bool,
         suggested: bool,
-        unsatisfied_const: bool,
     ) {
         let body_def_id = obligation.cause.body_id;
         let span = if let ObligationCauseCode::BinOp { rhs_span: Some(rhs_span), .. } =
@@ -2763,10 +2774,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                 self.tcx.def_span(trait_def_id),
                 crate::fluent_generated::trait_selection_trait_has_no_impls,
             );
-        } else if !suggested
-            && !unsatisfied_const
-            && trait_predicate.polarity() == ty::PredicatePolarity::Positive
-        {
+        } else if !suggested && trait_predicate.polarity() == ty::PredicatePolarity::Positive {
             // Can't show anything else useful, try to find similar impls.
             let impl_candidates = self.find_similar_impl_candidates(trait_predicate);
             if !self.report_similar_impl_candidates(
@@ -2878,17 +2886,6 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         }
     }
 
-    fn maybe_add_note_for_unsatisfied_const(
-        &self,
-        _trait_predicate: ty::PolyTraitPredicate<'tcx>,
-        _err: &mut Diag<'_>,
-        _span: Span,
-    ) -> UnsatisfiedConst {
-        let unsatisfied_const = UnsatisfiedConst(false);
-        // FIXME(const_trait_impl)
-        unsatisfied_const
-    }
-
     fn report_closure_error(
         &self,
         obligation: &PredicateObligation<'tcx>,
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs
index 1d8b934cef3..c8500b2d9d4 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs
@@ -51,8 +51,6 @@ enum GetSafeTransmuteErrorAndReason {
     Error { err_msg: String, safe_transmute_explanation: Option<String> },
 }
 
-struct UnsatisfiedConst(pub bool);
-
 /// Crude way of getting back an `Expr` from a `Span`.
 pub struct FindExprBySpan<'hir> {
     pub span: Span,
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
index bc8c8a44405..aa153d3607b 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs
@@ -820,16 +820,20 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         if matches!(obligation.cause.code(), ObligationCauseCode::FunctionArg { .. })
             && obligation.cause.span.can_be_used_for_suggestions()
         {
+            let (span, sugg) = if let Some(snippet) =
+                self.tcx.sess.source_map().span_to_snippet(obligation.cause.span).ok()
+                && snippet.starts_with("|")
+            {
+                (obligation.cause.span, format!("({snippet})({args})"))
+            } else {
+                (obligation.cause.span.shrink_to_hi(), format!("({args})"))
+            };
+
             // When the obligation error has been ensured to have been caused by
             // an argument, the `obligation.cause.span` points at the expression
             // of the argument, so we can provide a suggestion. Otherwise, we give
             // a more general note.
-            err.span_suggestion_verbose(
-                obligation.cause.span.shrink_to_hi(),
-                msg,
-                format!("({args})"),
-                Applicability::HasPlaceholders,
-            );
+            err.span_suggestion_verbose(span, msg, sugg, Applicability::HasPlaceholders);
         } else if let DefIdOrName::DefId(def_id) = def_id_or_name {
             let name = match self.tcx.hir_get_if_local(def_id) {
                 Some(hir::Node::Expr(hir::Expr {
@@ -2878,7 +2882,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                                 // we check if `TraitB` can be reachable from `S`
                                 // to determine whether to note `TraitA` is sealed trait.
                                 if let ty::Adt(adt, _) = ty.kind() {
-                                    let visibilities = tcx.effective_visibilities(());
+                                    let visibilities = &tcx.resolutions(()).effective_visibilities;
                                     visibilities.effective_vis(local).is_none_or(|v| {
                                         v.at_level(Level::Reexported)
                                             .is_accessible_from(adt.did(), tcx)
@@ -3853,59 +3857,71 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         }
     }
 
-    pub fn suggest_derive(
+    pub fn can_suggest_derive(
         &self,
         obligation: &PredicateObligation<'tcx>,
-        err: &mut Diag<'_>,
         trait_pred: ty::PolyTraitPredicate<'tcx>,
-    ) {
+    ) -> bool {
         if trait_pred.polarity() == ty::PredicatePolarity::Negative {
-            return;
+            return false;
         }
         let Some(diagnostic_name) = self.tcx.get_diagnostic_name(trait_pred.def_id()) else {
-            return;
+            return false;
         };
         let (adt, args) = match trait_pred.skip_binder().self_ty().kind() {
             ty::Adt(adt, args) if adt.did().is_local() => (adt, args),
-            _ => return,
+            _ => return false,
         };
-        let can_derive = {
-            let is_derivable_trait = match diagnostic_name {
-                sym::Default => !adt.is_enum(),
-                sym::PartialEq | sym::PartialOrd => {
-                    let rhs_ty = trait_pred.skip_binder().trait_ref.args.type_at(1);
-                    trait_pred.skip_binder().self_ty() == rhs_ty
-                }
-                sym::Eq | sym::Ord | sym::Clone | sym::Copy | sym::Hash | sym::Debug => true,
-                _ => false,
-            };
-            is_derivable_trait &&
-                // Ensure all fields impl the trait.
-                adt.all_fields().all(|field| {
-                    let field_ty = ty::GenericArg::from(field.ty(self.tcx, args));
-                    let trait_args = match diagnostic_name {
-                        sym::PartialEq | sym::PartialOrd => {
-                            Some(field_ty)
-                        }
-                        _ => None,
-                    };
-                    let trait_pred = trait_pred.map_bound_ref(|tr| ty::TraitPredicate {
-                        trait_ref: ty::TraitRef::new(self.tcx,
-                            trait_pred.def_id(),
-                            [field_ty].into_iter().chain(trait_args),
-                        ),
-                        ..*tr
-                    });
-                    let field_obl = Obligation::new(
-                        self.tcx,
-                        obligation.cause.clone(),
-                        obligation.param_env,
-                        trait_pred,
-                    );
-                    self.predicate_must_hold_modulo_regions(&field_obl)
-                })
+        let is_derivable_trait = match diagnostic_name {
+            sym::Default => !adt.is_enum(),
+            sym::PartialEq | sym::PartialOrd => {
+                let rhs_ty = trait_pred.skip_binder().trait_ref.args.type_at(1);
+                trait_pred.skip_binder().self_ty() == rhs_ty
+            }
+            sym::Eq | sym::Ord | sym::Clone | sym::Copy | sym::Hash | sym::Debug => true,
+            _ => false,
+        };
+        is_derivable_trait &&
+            // Ensure all fields impl the trait.
+            adt.all_fields().all(|field| {
+                let field_ty = ty::GenericArg::from(field.ty(self.tcx, args));
+                let trait_args = match diagnostic_name {
+                    sym::PartialEq | sym::PartialOrd => {
+                        Some(field_ty)
+                    }
+                    _ => None,
+                };
+                let trait_pred = trait_pred.map_bound_ref(|tr| ty::TraitPredicate {
+                    trait_ref: ty::TraitRef::new(self.tcx,
+                        trait_pred.def_id(),
+                        [field_ty].into_iter().chain(trait_args),
+                    ),
+                    ..*tr
+                });
+                let field_obl = Obligation::new(
+                    self.tcx,
+                    obligation.cause.clone(),
+                    obligation.param_env,
+                    trait_pred,
+                );
+                self.predicate_must_hold_modulo_regions(&field_obl)
+            })
+    }
+
+    pub fn suggest_derive(
+        &self,
+        obligation: &PredicateObligation<'tcx>,
+        err: &mut Diag<'_>,
+        trait_pred: ty::PolyTraitPredicate<'tcx>,
+    ) {
+        let Some(diagnostic_name) = self.tcx.get_diagnostic_name(trait_pred.def_id()) else {
+            return;
+        };
+        let adt = match trait_pred.skip_binder().self_ty().kind() {
+            ty::Adt(adt, _) if adt.did().is_local() => adt,
+            _ => return,
         };
-        if can_derive {
+        if self.can_suggest_derive(obligation, trait_pred) {
             err.span_suggestion_verbose(
                 self.tcx.def_span(adt.did()).shrink_to_lo(),
                 format!(
diff --git a/compiler/rustc_trait_selection/src/opaque_types.rs b/compiler/rustc_trait_selection/src/opaque_types.rs
index d5bde9192d5..bc7bdd372ba 100644
--- a/compiler/rustc_trait_selection/src/opaque_types.rs
+++ b/compiler/rustc_trait_selection/src/opaque_types.rs
@@ -4,8 +4,8 @@ use rustc_hir::def_id::LocalDefId;
 use rustc_infer::infer::outlives::env::OutlivesEnvironment;
 use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
 use rustc_middle::ty::{
-    self, DefiningScopeKind, GenericArgKind, GenericArgs, OpaqueTypeKey, TyCtxt, TypeVisitableExt,
-    TypingMode, fold_regions,
+    self, DefiningScopeKind, GenericArgKind, GenericArgs, OpaqueTypeKey, Ty, TyCtxt,
+    TypeVisitableExt, TypingMode, fold_regions,
 };
 use rustc_span::{ErrorGuaranteed, Span};
 
@@ -13,22 +13,23 @@ use crate::errors::NonGenericOpaqueTypeParam;
 use crate::regions::OutlivesEnvironmentBuildExt;
 use crate::traits::ObligationCtxt;
 
-pub enum InvalidOpaqueTypeArgs<'tcx> {
-    AlreadyReported(ErrorGuaranteed),
+#[derive(Debug)]
+pub enum NonDefiningUseReason<'tcx> {
+    Tainted(ErrorGuaranteed),
     NotAParam { opaque_type_key: OpaqueTypeKey<'tcx>, param_index: usize, span: Span },
     DuplicateParam { opaque_type_key: OpaqueTypeKey<'tcx>, param_indices: Vec<usize>, span: Span },
 }
-impl From<ErrorGuaranteed> for InvalidOpaqueTypeArgs<'_> {
+impl From<ErrorGuaranteed> for NonDefiningUseReason<'_> {
     fn from(guar: ErrorGuaranteed) -> Self {
-        InvalidOpaqueTypeArgs::AlreadyReported(guar)
+        NonDefiningUseReason::Tainted(guar)
     }
 }
-impl<'tcx> InvalidOpaqueTypeArgs<'tcx> {
+impl<'tcx> NonDefiningUseReason<'tcx> {
     pub fn report(self, infcx: &InferCtxt<'tcx>) -> ErrorGuaranteed {
         let tcx = infcx.tcx;
         match self {
-            InvalidOpaqueTypeArgs::AlreadyReported(guar) => guar,
-            InvalidOpaqueTypeArgs::NotAParam { opaque_type_key, param_index, span } => {
+            NonDefiningUseReason::Tainted(guar) => guar,
+            NonDefiningUseReason::NotAParam { opaque_type_key, param_index, span } => {
                 let opaque_generics = tcx.generics_of(opaque_type_key.def_id);
                 let opaque_param = opaque_generics.param_at(param_index, tcx);
                 let kind = opaque_param.kind.descr();
@@ -39,7 +40,7 @@ impl<'tcx> InvalidOpaqueTypeArgs<'tcx> {
                     param_span: tcx.def_span(opaque_param.def_id),
                 })
             }
-            InvalidOpaqueTypeArgs::DuplicateParam { opaque_type_key, param_indices, span } => {
+            NonDefiningUseReason::DuplicateParam { opaque_type_key, param_indices, span } => {
                 let opaque_generics = tcx.generics_of(opaque_type_key.def_id);
                 let descr = opaque_generics.param_at(param_indices[0], tcx).kind.descr();
                 let spans: Vec<_> = param_indices
@@ -57,15 +58,17 @@ impl<'tcx> InvalidOpaqueTypeArgs<'tcx> {
 }
 
 /// Opaque type parameter validity check as documented in the [rustc-dev-guide chapter].
+/// With the new solver, uses which fail this check are simply treated as non-defining
+/// and we only emit an error if no defining use exists.
 ///
 /// [rustc-dev-guide chapter]:
 /// https://rustc-dev-guide.rust-lang.org/opaque-types-region-infer-restrictions.html
-pub fn check_opaque_type_parameter_valid<'tcx>(
+pub fn opaque_type_has_defining_use_args<'tcx>(
     infcx: &InferCtxt<'tcx>,
     opaque_type_key: OpaqueTypeKey<'tcx>,
     span: Span,
     defining_scope_kind: DefiningScopeKind,
-) -> Result<(), InvalidOpaqueTypeArgs<'tcx>> {
+) -> Result<(), NonDefiningUseReason<'tcx>> {
     let tcx = infcx.tcx;
     let opaque_env = LazyOpaqueTyEnv::new(tcx, opaque_type_key.def_id);
     let mut seen_params: FxIndexMap<_, Vec<_>> = FxIndexMap::default();
@@ -104,13 +107,13 @@ pub fn check_opaque_type_parameter_valid<'tcx>(
         } else {
             // Prevent `fn foo() -> Foo<u32>` from being defining.
             opaque_env.param_is_error(i)?;
-            return Err(InvalidOpaqueTypeArgs::NotAParam { opaque_type_key, param_index: i, span });
+            return Err(NonDefiningUseReason::NotAParam { opaque_type_key, param_index: i, span });
         }
     }
 
     for (_, param_indices) in seen_params {
         if param_indices.len() > 1 {
-            return Err(InvalidOpaqueTypeArgs::DuplicateParam {
+            return Err(NonDefiningUseReason::DuplicateParam {
                 opaque_type_key,
                 param_indices,
                 span,
@@ -205,3 +208,27 @@ impl<'tcx> LazyOpaqueTyEnv<'tcx> {
         canonical_args
     }
 }
+
+pub fn report_item_does_not_constrain_error<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    item_def_id: LocalDefId,
+    def_id: LocalDefId,
+    non_defining_use: Option<(OpaqueTypeKey<'tcx>, Span)>,
+) -> ErrorGuaranteed {
+    let span = tcx.def_ident_span(item_def_id).unwrap_or_else(|| tcx.def_span(item_def_id));
+    let opaque_type_span = tcx.def_span(def_id);
+    let opaque_type_name = tcx.def_path_str(def_id);
+
+    let mut err =
+        tcx.dcx().struct_span_err(span, format!("item does not constrain `{opaque_type_name}`"));
+    err.note("consider removing `#[define_opaque]` or adding an empty `#[define_opaque()]`");
+    err.span_note(opaque_type_span, "this opaque type is supposed to be constrained");
+    if let Some((key, span)) = non_defining_use {
+        let opaque_ty = Ty::new_opaque(tcx, key.def_id.into(), key.args);
+        err.span_note(
+            span,
+            format!("this use of `{opaque_ty}` does not have unique universal generic arguments"),
+        );
+    }
+    err.emit()
+}
diff --git a/compiler/rustc_trait_selection/src/solve/fulfill.rs b/compiler/rustc_trait_selection/src/solve/fulfill.rs
index 3f628d80662..575e0472e0e 100644
--- a/compiler/rustc_trait_selection/src/solve/fulfill.rs
+++ b/compiler/rustc_trait_selection/src/solve/fulfill.rs
@@ -252,7 +252,9 @@ where
                         // inside of an opaque type, e.g. if there's `Opaque = (?x, ?x)` in the
                         // storage, we can also rely on structural identity of `?x` even if we
                         // later uniquify it in MIR borrowck.
-                        if infcx.in_hir_typeck && obligation.has_non_region_infer() {
+                        if infcx.in_hir_typeck
+                            && (obligation.has_non_region_infer() || obligation.has_free_regions())
+                        {
                             infcx.push_hir_typeck_potentially_region_dependent_goal(obligation);
                         }
                     }
diff --git a/compiler/rustc_trait_selection/src/traits/dyn_compatibility.rs b/compiler/rustc_trait_selection/src/traits/dyn_compatibility.rs
index ea1eed95723..4b493c95d59 100644
--- a/compiler/rustc_trait_selection/src/traits/dyn_compatibility.rs
+++ b/compiler/rustc_trait_selection/src/traits/dyn_compatibility.rs
@@ -106,6 +106,10 @@ fn dyn_compatibility_violations_for_trait(
     if !spans.is_empty() {
         violations.push(DynCompatibilityViolation::SupertraitNonLifetimeBinder(spans));
     }
+    let spans = super_predicates_are_unconditionally_const(tcx, trait_def_id);
+    if !spans.is_empty() {
+        violations.push(DynCompatibilityViolation::SupertraitConst(spans));
+    }
 
     violations
 }
@@ -247,16 +251,31 @@ fn super_predicates_have_non_lifetime_binders(
     tcx: TyCtxt<'_>,
     trait_def_id: DefId,
 ) -> SmallVec<[Span; 1]> {
-    // If non_lifetime_binders is disabled, then exit early
-    if !tcx.features().non_lifetime_binders() {
-        return SmallVec::new();
-    }
     tcx.explicit_super_predicates_of(trait_def_id)
         .iter_identity_copied()
         .filter_map(|(pred, span)| pred.has_non_region_bound_vars().then_some(span))
         .collect()
 }
 
+/// Checks for `const Trait` supertraits. We're okay with `[const] Trait`,
+/// supertraits since for a non-const instantiation of that trait, the
+/// conditionally-const supertrait is also not required to be const.
+fn super_predicates_are_unconditionally_const(
+    tcx: TyCtxt<'_>,
+    trait_def_id: DefId,
+) -> SmallVec<[Span; 1]> {
+    tcx.explicit_super_predicates_of(trait_def_id)
+        .iter_identity_copied()
+        .filter_map(|(pred, span)| {
+            if let ty::ClauseKind::HostEffect(_) = pred.kind().skip_binder() {
+                Some(span)
+            } else {
+                None
+            }
+        })
+        .collect()
+}
+
 fn trait_has_sized_self(tcx: TyCtxt<'_>, trait_def_id: DefId) -> bool {
     tcx.generics_require_sized_self(trait_def_id)
 }
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs
index 581191b2036..884d53732fe 100644
--- a/compiler/rustc_trait_selection/src/traits/project.rs
+++ b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -1507,7 +1507,7 @@ fn confirm_builtin_candidate<'cx, 'tcx>(
     let tcx = selcx.tcx();
     let self_ty = obligation.predicate.self_ty();
     let item_def_id = obligation.predicate.def_id;
-    let trait_def_id = tcx.trait_of_assoc(item_def_id).unwrap();
+    let trait_def_id = tcx.parent(item_def_id);
     let args = tcx.mk_args(&[self_ty.into()]);
     let (term, obligations) = if tcx.is_lang_item(trait_def_id, LangItem::DiscriminantKind) {
         let discriminant_def_id =
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs
index 0ca2d216228..6ce68507d65 100644
--- a/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs
@@ -1,6 +1,7 @@
 use std::fmt;
 
 use rustc_errors::ErrorGuaranteed;
+use rustc_hir::def_id::LocalDefId;
 use rustc_infer::infer::region_constraints::RegionConstraintData;
 use rustc_middle::traits::query::NoSolution;
 use rustc_middle::ty::{TyCtxt, TypeFoldable};
@@ -42,13 +43,14 @@ where
     fn fully_perform(
         self,
         infcx: &InferCtxt<'tcx>,
+        root_def_id: LocalDefId,
         span: Span,
     ) -> Result<TypeOpOutput<'tcx, Self>, ErrorGuaranteed> {
         if cfg!(debug_assertions) {
             info!("fully_perform({:?})", self);
         }
 
-        Ok(scrape_region_constraints(infcx, self.closure, self.description, span)?.0)
+        Ok(scrape_region_constraints(infcx, root_def_id, self.description, span, self.closure)?.0)
     }
 }
 
@@ -62,9 +64,10 @@ impl<F> fmt::Debug for CustomTypeOp<F> {
 /// constraints that result, creating query-region-constraints.
 pub fn scrape_region_constraints<'tcx, Op, R>(
     infcx: &InferCtxt<'tcx>,
-    op: impl FnOnce(&ObligationCtxt<'_, 'tcx>) -> Result<R, NoSolution>,
+    root_def_id: LocalDefId,
     name: &'static str,
     span: Span,
+    op: impl FnOnce(&ObligationCtxt<'_, 'tcx>) -> Result<R, NoSolution>,
 ) -> Result<(TypeOpOutput<'tcx, Op>, RegionConstraintData<'tcx>), ErrorGuaranteed>
 where
     R: TypeFoldable<TyCtxt<'tcx>>,
@@ -94,6 +97,8 @@ where
         let errors = ocx.select_all_or_error();
         if errors.is_empty() {
             Ok(value)
+        } else if let Err(guar) = infcx.tcx.check_potentially_region_dependent_goals(root_def_id) {
+            Err(guar)
         } else {
             Err(infcx
                 .dcx()
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs
index 018e9748cf0..4b8bf868123 100644
--- a/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs
@@ -1,6 +1,7 @@
 use std::fmt;
 
 use rustc_errors::ErrorGuaranteed;
+use rustc_hir::def_id::LocalDefId;
 use rustc_infer::traits::PredicateObligations;
 use rustc_middle::traits::query::NoSolution;
 use rustc_middle::ty::{ParamEnvAnd, TyCtxt, TypeFoldable};
@@ -37,6 +38,7 @@ pub trait TypeOp<'tcx>: Sized + fmt::Debug {
     fn fully_perform(
         self,
         infcx: &InferCtxt<'tcx>,
+        root_def_id: LocalDefId,
         span: Span,
     ) -> Result<TypeOpOutput<'tcx, Self>, ErrorGuaranteed>;
 }
@@ -140,6 +142,7 @@ where
     fn fully_perform(
         self,
         infcx: &InferCtxt<'tcx>,
+        root_def_id: LocalDefId,
         span: Span,
     ) -> Result<TypeOpOutput<'tcx, Self>, ErrorGuaranteed> {
         // In the new trait solver, query type ops are performed locally. This
@@ -152,9 +155,10 @@ where
         if infcx.next_trait_solver() {
             return Ok(scrape_region_constraints(
                 infcx,
-                |ocx| QueryTypeOp::perform_locally_with_next_solver(ocx, self, span),
+                root_def_id,
                 "query type op",
                 span,
+                |ocx| QueryTypeOp::perform_locally_with_next_solver(ocx, self, span),
             )?
             .0);
         }
@@ -166,19 +170,15 @@ where
         // we sometimes end up with `Opaque<'a> = Opaque<'b>` instead of an actual hidden type. In that case we don't register a
         // hidden type but just equate the lifetimes. Thus we need to scrape the region constraints even though we're also manually
         // collecting region constraints via `region_constraints`.
-        let (mut output, _) = scrape_region_constraints(
-            infcx,
-            |ocx| {
+        let (mut output, _) =
+            scrape_region_constraints(infcx, root_def_id, "fully_perform", span, |ocx| {
                 let (output, ei, obligations, _) =
                     Q::fully_perform_into(self, infcx, &mut region_constraints, span)?;
                 error_info = ei;
 
                 ocx.register_obligations(obligations);
                 Ok(output)
-            },
-            "fully_perform",
-            span,
-        )?;
+            })?;
         output.error_info = error_info;
         if let Some(QueryRegionConstraints { outlives, assumptions }) = output.constraints {
             region_constraints.outlives.extend(outlives.iter().cloned());
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index 468c42abf48..1dd31990ab7 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -4,9 +4,9 @@
 
 use std::assert_matches::assert_matches;
 use std::cell::{Cell, RefCell};
+use std::cmp;
 use std::fmt::{self, Display};
 use std::ops::ControlFlow;
-use std::{cmp, iter};
 
 use hir::def::DefKind;
 use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
@@ -2185,32 +2185,23 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
                 ty::Binder::dummy(vec![ty])
             }
 
-            ty::Coroutine(coroutine_def_id, args) => {
-                match self.tcx().coroutine_movability(coroutine_def_id) {
-                    hir::Movability::Static => {
-                        unreachable!("tried to assemble `Sized` for static coroutine")
-                    }
-                    hir::Movability::Movable => {
-                        if self.tcx().features().coroutine_clone() {
-                            ty::Binder::dummy(
-                                args.as_coroutine()
-                                    .upvar_tys()
-                                    .iter()
-                                    .chain([Ty::new_coroutine_witness(
-                                        self.tcx(),
-                                        coroutine_def_id,
-                                        self.tcx().mk_args(args.as_coroutine().parent_args()),
-                                    )])
-                                    .collect::<Vec<_>>(),
-                            )
-                        } else {
-                            unreachable!(
-                                "tried to assemble `Sized` for coroutine without enabled feature"
-                            )
-                        }
+            ty::Coroutine(def_id, args) => match self.tcx().coroutine_movability(def_id) {
+                hir::Movability::Static => {
+                    unreachable!("tried to assemble `Clone` for static coroutine")
+                }
+                hir::Movability::Movable => {
+                    if self.tcx().features().coroutine_clone() {
+                        ty::Binder::dummy(vec![
+                            args.as_coroutine().tupled_upvars_ty(),
+                            Ty::new_coroutine_witness_for_coroutine(self.tcx(), def_id, args),
+                        ])
+                    } else {
+                        unreachable!(
+                            "tried to assemble `Clone` for coroutine without enabled feature"
+                        )
                     }
                 }
-            }
+            },
 
             ty::CoroutineWitness(def_id, args) => self
                 .infcx
@@ -2334,25 +2325,9 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
             ty::Coroutine(def_id, args) => {
                 let ty = self.infcx.shallow_resolve(args.as_coroutine().tupled_upvars_ty());
                 let tcx = self.tcx();
-                let witness = Ty::new_coroutine_witness(
-                    tcx,
-                    def_id,
-                    ty::GenericArgs::for_item(tcx, def_id, |def, _| match def.kind {
-                        // HACK: Coroutine witnesse types are lifetime erased, so they
-                        // never reference any lifetime args from the coroutine. We erase
-                        // the regions here since we may get into situations where a
-                        // coroutine is recursively contained within itself, leading to
-                        // witness types that differ by region args. This means that
-                        // cycle detection in fulfillment will not kick in, which leads
-                        // to unnecessary overflows in async code. See the issue:
-                        // <https://github.com/rust-lang/rust/issues/145151>.
-                        ty::GenericParamDefKind::Lifetime => tcx.lifetimes.re_erased.into(),
-                        ty::GenericParamDefKind::Type { .. }
-                        | ty::GenericParamDefKind::Const { .. } => args[def.index as usize],
-                    }),
-                );
+                let witness = Ty::new_coroutine_witness_for_coroutine(tcx, def_id, args);
                 ty::Binder::dummy(AutoImplConstituents {
-                    types: [ty].into_iter().chain(iter::once(witness)).collect(),
+                    types: vec![ty, witness],
                     assumptions: vec![],
                 })
             }
diff --git a/compiler/rustc_trait_selection/src/traits/util.rs b/compiler/rustc_trait_selection/src/traits/util.rs
index 83c0969762f..335942d5bcc 100644
--- a/compiler/rustc_trait_selection/src/traits/util.rs
+++ b/compiler/rustc_trait_selection/src/traits/util.rs
@@ -9,8 +9,8 @@ pub use rustc_infer::traits::util::*;
 use rustc_middle::bug;
 use rustc_middle::ty::fast_reject::DeepRejectCtxt;
 use rustc_middle::ty::{
-    self, PolyTraitPredicate, SizedTraitKind, TraitPredicate, TraitRef, Ty, TyCtxt, TypeFoldable,
-    TypeFolder, TypeSuperFoldable, TypeVisitableExt,
+    self, PolyTraitPredicate, PredicatePolarity, SizedTraitKind, TraitPredicate, TraitRef, Ty,
+    TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable, TypeVisitableExt,
 };
 pub use rustc_next_trait_solver::placeholder::BoundVarReplacer;
 use rustc_span::Span;
@@ -427,7 +427,9 @@ pub(crate) fn lazily_elaborate_sizedness_candidate<'tcx>(
         return candidate;
     }
 
-    if obligation.predicate.polarity() != candidate.polarity() {
+    if obligation.predicate.polarity() != PredicatePolarity::Positive
+        || candidate.polarity() != PredicatePolarity::Positive
+    {
         return candidate;
     }
 
diff --git a/compiler/rustc_traits/Cargo.toml b/compiler/rustc_traits/Cargo.toml
index 04aef4e7b9e..24360a94cc7 100644
--- a/compiler/rustc_traits/Cargo.toml
+++ b/compiler/rustc_traits/Cargo.toml
@@ -6,10 +6,9 @@ edition = "2024"
 [dependencies]
 # tidy-alphabetical-start
 rustc_data_structures = { path = "../rustc_data_structures" }
-rustc_hir = { path = "../rustc_hir" }
 rustc_infer = { path = "../rustc_infer" }
 rustc_middle = { path = "../rustc_middle" }
 rustc_span = { path = "../rustc_span" }
 rustc_trait_selection = { path = "../rustc_trait_selection" }
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_traits/src/coroutine_witnesses.rs b/compiler/rustc_traits/src/coroutine_witnesses.rs
index 8a2a0832ddb..20f9b013724 100644
--- a/compiler/rustc_traits/src/coroutine_witnesses.rs
+++ b/compiler/rustc_traits/src/coroutine_witnesses.rs
@@ -1,9 +1,9 @@
-use rustc_hir::def_id::DefId;
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_infer::infer::canonical::query_response::make_query_region_constraints;
 use rustc_infer::infer::resolve::OpportunisticRegionResolver;
 use rustc_infer::traits::{Obligation, ObligationCause};
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, TypeVisitableExt, fold_regions};
+use rustc_span::def_id::DefId;
 use rustc_trait_selection::traits::{ObligationCtxt, with_replaced_escaping_bound_vars};
 
 /// Return the set of types that should be taken into account when checking
diff --git a/compiler/rustc_traits/src/dropck_outlives.rs b/compiler/rustc_traits/src/dropck_outlives.rs
index 5eddad39e2b..d33ade7a9e1 100644
--- a/compiler/rustc_traits/src/dropck_outlives.rs
+++ b/compiler/rustc_traits/src/dropck_outlives.rs
@@ -1,5 +1,4 @@
 use rustc_data_structures::fx::FxHashSet;
-use rustc_hir::def_id::DefId;
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_infer::infer::canonical::{Canonical, QueryResponse};
 use rustc_middle::bug;
@@ -7,6 +6,7 @@ use rustc_middle::query::Providers;
 use rustc_middle::traits::query::{DropckConstraint, DropckOutlivesResult};
 use rustc_middle::ty::{self, GenericArgs, TyCtxt};
 use rustc_span::DUMMY_SP;
+use rustc_span::def_id::DefId;
 use rustc_trait_selection::infer::InferCtxtBuilderExt;
 use rustc_trait_selection::traits::query::dropck_outlives::{
     compute_dropck_outlives_inner, dtorck_constraint_for_ty_inner,
diff --git a/compiler/rustc_transmute/Cargo.toml b/compiler/rustc_transmute/Cargo.toml
index e61717e5e9c..2ac2b46cc58 100644
--- a/compiler/rustc_transmute/Cargo.toml
+++ b/compiler/rustc_transmute/Cargo.toml
@@ -11,12 +11,12 @@ rustc_hir = { path = "../rustc_hir", optional = true }
 rustc_middle = { path = "../rustc_middle", optional = true }
 rustc_span = { path = "../rustc_span", optional = true }
 smallvec = "1.8.1"
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
 
 [dev-dependencies]
 # tidy-alphabetical-start
-itertools = "0.12"
+itertools.workspace = true
 # tidy-alphabetical-end
 
 [features]
diff --git a/compiler/rustc_ty_utils/Cargo.toml b/compiler/rustc_ty_utils/Cargo.toml
index ce08b300cc8..394cde5a323 100644
--- a/compiler/rustc_ty_utils/Cargo.toml
+++ b/compiler/rustc_ty_utils/Cargo.toml
@@ -5,7 +5,7 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-itertools = "0.12"
+itertools.workspace = true
 rustc_abi = { path = "../rustc_abi" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
@@ -20,5 +20,5 @@ rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 rustc_trait_selection = { path = "../rustc_trait_selection" }
-tracing = "0.1"
+tracing.workspace = true
 # tidy-alphabetical-end
diff --git a/compiler/rustc_ty_utils/src/abi.rs b/compiler/rustc_ty_utils/src/abi.rs
index 89d1dd8cf23..e4ed084b073 100644
--- a/compiler/rustc_ty_utils/src/abi.rs
+++ b/compiler/rustc_ty_utils/src/abi.rs
@@ -356,6 +356,7 @@ fn arg_attrs_for_rust_scalar<'tcx>(
 
             if matches!(kind, PointerKind::SharedRef { frozen: true }) && !is_return {
                 attrs.set(ArgAttribute::ReadOnly);
+                attrs.set(ArgAttribute::CapturesReadOnly);
             }
         }
     }
diff --git a/compiler/rustc_type_ir/Cargo.toml b/compiler/rustc_type_ir/Cargo.toml
index e7fee574dd4..1dba7fe4269 100644
--- a/compiler/rustc_type_ir/Cargo.toml
+++ b/compiler/rustc_type_ir/Cargo.toml
@@ -5,21 +5,22 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-bitflags = "2.4.1"
+bitflags.workspace = true
 derive-where = "1.2.7"
 ena = "0.14.3"
 indexmap = "2.0.0"
 rustc-hash = "2.0.0"
 rustc_ast_ir = { path = "../rustc_ast_ir", default-features = false }
 rustc_data_structures = { path = "../rustc_data_structures", optional = true }
+rustc_error_messages = { path = "../rustc_error_messages", optional = true }
 rustc_index = { path = "../rustc_index", default-features = false }
 rustc_macros = { path = "../rustc_macros", optional = true }
 rustc_serialize = { path = "../rustc_serialize", optional = true }
 rustc_span = { path = "../rustc_span", optional = true }
 rustc_type_ir_macros = { path = "../rustc_type_ir_macros" }
 smallvec = { version = "1.8.1", default-features = false, features = ["const_generics"] }
-thin-vec = "0.2.12"
-tracing = "0.1"
+thin-vec.workspace = true
+tracing.workspace = true
 # tidy-alphabetical-end
 
 [features]
@@ -27,6 +28,7 @@ tracing = "0.1"
 default = ["nightly"]
 nightly = [
     "dep:rustc_data_structures",
+    "dep:rustc_error_messages",
     "dep:rustc_macros",
     "dep:rustc_serialize",
     "dep:rustc_span",
diff --git a/compiler/rustc_type_ir/src/infer_ctxt.rs b/compiler/rustc_type_ir/src/infer_ctxt.rs
index e39b99e992b..b4462294700 100644
--- a/compiler/rustc_type_ir/src/infer_ctxt.rs
+++ b/compiler/rustc_type_ir/src/infer_ctxt.rs
@@ -148,10 +148,6 @@ pub trait InferCtxtLike: Sized {
         true
     }
 
-    fn in_hir_typeck(&self) -> bool {
-        false
-    }
-
     fn typing_mode(&self) -> TypingMode<Self::Interner>;
 
     fn universe(&self) -> ty::UniverseIndex;
diff --git a/compiler/rustc_type_ir/src/inherent.rs b/compiler/rustc_type_ir/src/inherent.rs
index 1a6c99ce7de..569570b5783 100644
--- a/compiler/rustc_type_ir/src/inherent.rs
+++ b/compiler/rustc_type_ir/src/inherent.rs
@@ -91,6 +91,12 @@ pub trait Ty<I: Interner<Ty = Self>>:
 
     fn new_coroutine_witness(interner: I, def_id: I::DefId, args: I::GenericArgs) -> Self;
 
+    fn new_coroutine_witness_for_coroutine(
+        interner: I,
+        def_id: I::DefId,
+        coroutine_args: I::GenericArgs,
+    ) -> Self;
+
     fn new_ptr(interner: I, ty: Self, mutbl: Mutability) -> Self;
 
     fn new_ref(interner: I, region: I::Region, ty: Self, mutbl: Mutability) -> Self;
diff --git a/compiler/rustc_type_ir/src/ir_print.rs b/compiler/rustc_type_ir/src/ir_print.rs
index 388ad09cb20..82bb8791b84 100644
--- a/compiler/rustc_type_ir/src/ir_print.rs
+++ b/compiler/rustc_type_ir/src/ir_print.rs
@@ -1,9 +1,9 @@
 use std::fmt;
 
 use crate::{
-    AliasTerm, AliasTy, Binder, CoercePredicate, ExistentialProjection, ExistentialTraitRef, FnSig,
-    HostEffectPredicate, Interner, NormalizesTo, OutlivesPredicate, PatternKind,
-    ProjectionPredicate, SubtypePredicate, TraitPredicate, TraitRef,
+    AliasTerm, AliasTy, Binder, ClosureKind, CoercePredicate, ExistentialProjection,
+    ExistentialTraitRef, FnSig, HostEffectPredicate, Interner, NormalizesTo, OutlivesPredicate,
+    PatternKind, ProjectionPredicate, SubtypePredicate, TraitPredicate, TraitRef, UnevaluatedConst,
 };
 
 pub trait IrPrint<T> {
@@ -70,3 +70,46 @@ where
         <I as IrPrint<OutlivesPredicate<I, T>>>::print(self, fmt)
     }
 }
+
+#[cfg(feature = "nightly")]
+mod into_diag_arg_impls {
+    use rustc_error_messages::{DiagArgValue, IntoDiagArg};
+
+    use super::*;
+
+    impl<I: Interner> IntoDiagArg for TraitRef<I> {
+        fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+            self.to_string().into_diag_arg(path)
+        }
+    }
+
+    impl<I: Interner> IntoDiagArg for ExistentialTraitRef<I> {
+        fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+            self.to_string().into_diag_arg(path)
+        }
+    }
+
+    impl<I: Interner> IntoDiagArg for UnevaluatedConst<I> {
+        fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+            format!("{self:?}").into_diag_arg(path)
+        }
+    }
+
+    impl<I: Interner> IntoDiagArg for FnSig<I> {
+        fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+            format!("{self:?}").into_diag_arg(path)
+        }
+    }
+
+    impl<I: Interner, T: IntoDiagArg> IntoDiagArg for Binder<I, T> {
+        fn into_diag_arg(self, path: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+            self.skip_binder().into_diag_arg(path)
+        }
+    }
+
+    impl IntoDiagArg for ClosureKind {
+        fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
+            DiagArgValue::Str(self.as_str().into())
+        }
+    }
+}
diff --git a/compiler/rustc_type_ir/src/region_kind.rs b/compiler/rustc_type_ir/src/region_kind.rs
index cca81dcb4a0..06048af0436 100644
--- a/compiler/rustc_type_ir/src/region_kind.rs
+++ b/compiler/rustc_type_ir/src/region_kind.rs
@@ -154,7 +154,7 @@ pub enum RegionKind<I: Interner> {
     /// parameters via `tcx.liberate_late_bound_regions`. They are then treated
     /// the same way as `ReEarlyParam` while inside of the function.
     ///
-    /// See <https://rustc-dev-guide.rust-lang.org/early-late-bound-params/early-late-bound-summary.html> for
+    /// See <https://rustc-dev-guide.rust-lang.org/early_late_parameters.html> for
     /// more info about early and late bound lifetime parameters.
     ReLateParam(I::LateParamRegion),
 
diff --git a/compiler/rustc_type_ir/src/search_graph/mod.rs b/compiler/rustc_type_ir/src/search_graph/mod.rs
index daacb4a3e44..348178a527f 100644
--- a/compiler/rustc_type_ir/src/search_graph/mod.rs
+++ b/compiler/rustc_type_ir/src/search_graph/mod.rs
@@ -12,10 +12,11 @@
 //! The global cache has to be completely unobservable, while the per-cycle cache may impact
 //! behavior as long as the resulting behavior is still correct.
 use std::cmp::Ordering;
-use std::collections::BTreeMap;
 use std::collections::hash_map::Entry;
+use std::collections::{BTreeMap, btree_map};
 use std::fmt::Debug;
 use std::hash::Hash;
+use std::iter;
 use std::marker::PhantomData;
 
 use derive_where::derive_where;
@@ -169,27 +170,76 @@ impl PathKind {
 /// This is used to avoid rerunning a cycle if there's
 /// just a single usage kind and the final result matches
 /// its provisional result.
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub enum UsageKind {
-    Single(PathKind),
-    Mixed,
+///
+/// While it tracks the amount of usages using `u32`, we only ever
+/// care whether there are any. We only count them to be able to ignore
+/// usages from irrelevant candidates while evaluating a goal.
+///
+/// This cares about how nested goals relied on a cycle head. It does
+/// not care about how frequently the nested goal relied on it.
+#[derive(Default, Debug, Clone, Copy, PartialEq, Eq)]
+struct HeadUsages {
+    inductive: u32,
+    unknown: u32,
+    coinductive: u32,
+    forced_ambiguity: u32,
 }
-impl From<PathKind> for UsageKind {
-    fn from(path: PathKind) -> UsageKind {
-        UsageKind::Single(path)
+
+impl HeadUsages {
+    fn add_usage(&mut self, path: PathKind) {
+        match path {
+            PathKind::Inductive => self.inductive += 1,
+            PathKind::Unknown => self.unknown += 1,
+            PathKind::Coinductive => self.coinductive += 1,
+            PathKind::ForcedAmbiguity => self.forced_ambiguity += 1,
+        }
+    }
+
+    /// This adds the usages which occurred while computing a nested goal.
+    ///
+    /// We don't actually care about how frequently the nested goal relied
+    /// on its cycle heads, only whether it did.
+    fn add_usages_from_nested(&mut self, usages: HeadUsages) {
+        let HeadUsages { inductive, unknown, coinductive, forced_ambiguity } = usages;
+        self.inductive += if inductive == 0 { 0 } else { 1 };
+        self.unknown += if unknown == 0 { 0 } else { 1 };
+        self.coinductive += if coinductive == 0 { 0 } else { 1 };
+        self.forced_ambiguity += if forced_ambiguity == 0 { 0 } else { 1 };
+    }
+
+    fn ignore_usages(&mut self, usages: HeadUsages) {
+        let HeadUsages { inductive, unknown, coinductive, forced_ambiguity } = usages;
+        self.inductive = self.inductive.checked_sub(inductive).unwrap();
+        self.unknown = self.unknown.checked_sub(unknown).unwrap();
+        self.coinductive = self.coinductive.checked_sub(coinductive).unwrap();
+        self.forced_ambiguity = self.forced_ambiguity.checked_sub(forced_ambiguity).unwrap();
+    }
+
+    fn is_empty(self) -> bool {
+        let HeadUsages { inductive, unknown, coinductive, forced_ambiguity } = self;
+        inductive == 0 && unknown == 0 && coinductive == 0 && forced_ambiguity == 0
     }
 }
-impl UsageKind {
-    #[must_use]
-    fn merge(self, other: impl Into<Self>) -> Self {
-        match (self, other.into()) {
-            (UsageKind::Mixed, _) | (_, UsageKind::Mixed) => UsageKind::Mixed,
-            (UsageKind::Single(lhs), UsageKind::Single(rhs)) => {
-                if lhs == rhs {
-                    UsageKind::Single(lhs)
-                } else {
-                    UsageKind::Mixed
+
+#[derive(Debug, Default)]
+pub struct CandidateHeadUsages {
+    usages: Option<Box<HashMap<StackDepth, HeadUsages>>>,
+}
+impl CandidateHeadUsages {
+    pub fn merge_usages(&mut self, other: CandidateHeadUsages) {
+        if let Some(other_usages) = other.usages {
+            if let Some(ref mut self_usages) = self.usages {
+                #[allow(rustc::potential_query_instability)]
+                for (head_index, head) in other_usages.into_iter() {
+                    let HeadUsages { inductive, unknown, coinductive, forced_ambiguity } = head;
+                    let self_usages = self_usages.entry(head_index).or_default();
+                    self_usages.inductive += inductive;
+                    self_usages.unknown += unknown;
+                    self_usages.coinductive += coinductive;
+                    self_usages.forced_ambiguity += forced_ambiguity;
                 }
+            } else {
+                self.usages = Some(other_usages);
             }
         }
     }
@@ -230,13 +280,24 @@ impl AvailableDepth {
     }
 }
 
+#[derive(Clone, Copy, Debug)]
+struct CycleHead {
+    paths_to_head: PathsToNested,
+    /// If the `usages` are empty, the result of that head does not matter
+    /// for the current goal. However, we still don't completely drop this
+    /// cycle head as whether or not it exists impacts which queries we
+    /// access, so ignoring it would cause incremental compilation verification
+    /// failures or hide query cycles.
+    usages: HeadUsages,
+}
+
 /// All cycle heads a given goal depends on, ordered by their stack depth.
 ///
 /// We also track all paths from this goal to that head. This is necessary
 /// when rebasing provisional cache results.
 #[derive(Clone, Debug, Default)]
 struct CycleHeads {
-    heads: BTreeMap<StackDepth, PathsToNested>,
+    heads: BTreeMap<StackDepth, CycleHead>,
 }
 
 impl CycleHeads {
@@ -244,43 +305,51 @@ impl CycleHeads {
         self.heads.is_empty()
     }
 
-    fn highest_cycle_head(&self) -> StackDepth {
-        self.opt_highest_cycle_head().unwrap()
+    fn highest_cycle_head(&self) -> (StackDepth, CycleHead) {
+        self.heads.last_key_value().map(|(k, v)| (*k, *v)).unwrap()
     }
 
-    fn opt_highest_cycle_head(&self) -> Option<StackDepth> {
+    fn highest_cycle_head_index(&self) -> StackDepth {
+        self.opt_highest_cycle_head_index().unwrap()
+    }
+
+    fn opt_highest_cycle_head_index(&self) -> Option<StackDepth> {
         self.heads.last_key_value().map(|(k, _)| *k)
     }
 
-    fn opt_lowest_cycle_head(&self) -> Option<StackDepth> {
+    fn opt_lowest_cycle_head_index(&self) -> Option<StackDepth> {
         self.heads.first_key_value().map(|(k, _)| *k)
     }
 
-    fn remove_highest_cycle_head(&mut self) -> PathsToNested {
+    fn remove_highest_cycle_head(&mut self) -> CycleHead {
         let last = self.heads.pop_last();
         last.unwrap().1
     }
 
-    fn insert(&mut self, head: StackDepth, path_from_entry: impl Into<PathsToNested> + Copy) {
-        *self.heads.entry(head).or_insert(path_from_entry.into()) |= path_from_entry.into();
+    fn insert(
+        &mut self,
+        head_index: StackDepth,
+        path_from_entry: impl Into<PathsToNested> + Copy,
+        usages: HeadUsages,
+    ) {
+        match self.heads.entry(head_index) {
+            btree_map::Entry::Vacant(entry) => {
+                entry.insert(CycleHead { paths_to_head: path_from_entry.into(), usages });
+            }
+            btree_map::Entry::Occupied(entry) => {
+                let head = entry.into_mut();
+                head.paths_to_head |= path_from_entry.into();
+                head.usages.add_usages_from_nested(usages);
+            }
+        }
     }
 
-    fn iter(&self) -> impl Iterator<Item = (StackDepth, PathsToNested)> + '_ {
-        self.heads.iter().map(|(k, v)| (*k, *v))
+    fn ignore_usages(&mut self, head_index: StackDepth, usages: HeadUsages) {
+        self.heads.get_mut(&head_index).unwrap().usages.ignore_usages(usages)
     }
 
-    /// Update the cycle heads of a goal at depth `this` given the cycle heads
-    /// of a nested goal. This merges the heads after filtering the parent goal
-    /// itself.
-    fn extend_from_child(&mut self, this: StackDepth, step_kind: PathKind, child: &CycleHeads) {
-        for (&head, &path_from_entry) in child.heads.iter() {
-            match head.cmp(&this) {
-                Ordering::Less => {}
-                Ordering::Equal => continue,
-                Ordering::Greater => unreachable!(),
-            }
-            self.insert(head, path_from_entry.extend_with(step_kind));
-        }
+    fn iter(&self) -> impl Iterator<Item = (StackDepth, CycleHead)> + '_ {
+        self.heads.iter().map(|(k, v)| (*k, *v))
     }
 }
 
@@ -487,9 +556,6 @@ impl<X: Cx> EvaluationResult<X> {
 
 pub struct SearchGraph<D: Delegate<Cx = X>, X: Cx = <D as Delegate>::Cx> {
     root_depth: AvailableDepth,
-    /// The stack of goals currently being computed.
-    ///
-    /// An element is *deeper* in the stack if its index is *lower*.
     stack: Stack<X>,
     /// The provisional cache contains entries for already computed goals which
     /// still depend on goals higher-up in the stack. We don't move them to the
@@ -511,6 +577,7 @@ pub struct SearchGraph<D: Delegate<Cx = X>, X: Cx = <D as Delegate>::Cx> {
 /// cache entry.
 enum UpdateParentGoalCtxt<'a, X: Cx> {
     Ordinary(&'a NestedGoals<X>),
+    CycleOnStack(X::Input),
     ProvisionalCacheHit,
 }
 
@@ -532,21 +599,47 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
         stack: &mut Stack<X>,
         step_kind_from_parent: PathKind,
         required_depth_for_nested: usize,
-        heads: &CycleHeads,
+        heads: impl Iterator<Item = (StackDepth, CycleHead)>,
         encountered_overflow: bool,
         context: UpdateParentGoalCtxt<'_, X>,
     ) {
-        if let Some(parent_index) = stack.last_index() {
-            let parent = &mut stack[parent_index];
+        if let Some((parent_index, parent)) = stack.last_mut_with_index() {
             parent.required_depth = parent.required_depth.max(required_depth_for_nested + 1);
             parent.encountered_overflow |= encountered_overflow;
 
-            parent.heads.extend_from_child(parent_index, step_kind_from_parent, heads);
+            for (head_index, head) in heads {
+                if let Some(candidate_usages) = &mut parent.candidate_usages {
+                    candidate_usages
+                        .usages
+                        .get_or_insert_default()
+                        .entry(head_index)
+                        .or_default()
+                        .add_usages_from_nested(head.usages);
+                }
+                match head_index.cmp(&parent_index) {
+                    Ordering::Less => parent.heads.insert(
+                        head_index,
+                        head.paths_to_head.extend_with(step_kind_from_parent),
+                        head.usages,
+                    ),
+                    Ordering::Equal => {
+                        parent.usages.get_or_insert_default().add_usages_from_nested(head.usages);
+                    }
+                    Ordering::Greater => unreachable!(),
+                }
+            }
             let parent_depends_on_cycle = match context {
                 UpdateParentGoalCtxt::Ordinary(nested_goals) => {
                     parent.nested_goals.extend_from_child(step_kind_from_parent, nested_goals);
                     !nested_goals.is_empty()
                 }
+                UpdateParentGoalCtxt::CycleOnStack(head) => {
+                    // We lookup provisional cache entries before detecting cycles.
+                    // We therefore can't use a global cache entry if it contains a cycle
+                    // whose head is in the provisional cache.
+                    parent.nested_goals.insert(head, step_kind_from_parent.into());
+                    true
+                }
                 UpdateParentGoalCtxt::ProvisionalCacheHit => true,
             };
             // Once we've got goals which encountered overflow or a cycle,
@@ -587,6 +680,29 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
         stack.cycle_step_kinds(head).fold(step_kind_to_head, |curr, step| curr.extend(step))
     }
 
+    pub fn enter_single_candidate(&mut self) {
+        let prev = self.stack.last_mut().unwrap().candidate_usages.replace(Default::default());
+        debug_assert!(prev.is_none(), "existing candidate_usages: {prev:?}");
+    }
+
+    pub fn finish_single_candidate(&mut self) -> CandidateHeadUsages {
+        self.stack.last_mut().unwrap().candidate_usages.take().unwrap()
+    }
+
+    pub fn ignore_candidate_head_usages(&mut self, usages: CandidateHeadUsages) {
+        if let Some(usages) = usages.usages {
+            let (entry_index, entry) = self.stack.last_mut_with_index().unwrap();
+            #[allow(rustc::potential_query_instability)]
+            for (head_index, usages) in usages.into_iter() {
+                if head_index == entry_index {
+                    entry.usages.unwrap().ignore_usages(usages);
+                } else {
+                    entry.heads.ignore_usages(head_index, usages);
+                }
+            }
+        }
+    }
+
     /// Probably the most involved method of the whole solver.
     ///
     /// While goals get computed via `D::compute_goal`, this function handles
@@ -655,7 +771,8 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
             required_depth: 0,
             heads: Default::default(),
             encountered_overflow: false,
-            has_been_used: None,
+            usages: None,
+            candidate_usages: None,
             nested_goals: Default::default(),
         });
 
@@ -674,7 +791,7 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
             &mut self.stack,
             step_kind_from_parent,
             evaluation_result.required_depth,
-            &evaluation_result.heads,
+            evaluation_result.heads.iter(),
             evaluation_result.encountered_overflow,
             UpdateParentGoalCtxt::Ordinary(&evaluation_result.nested_goals),
         );
@@ -703,7 +820,7 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
             let path_from_head = Self::cycle_path_kind(
                 &self.stack,
                 step_kind_from_parent,
-                heads.highest_cycle_head(),
+                heads.highest_cycle_head_index(),
             );
             let provisional_cache_entry =
                 ProvisionalCacheEntry { encountered_overflow, heads, path_from_head, result };
@@ -741,11 +858,17 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
 
     /// When reevaluating a goal with a changed provisional result, all provisional cache entry
     /// which depend on this goal get invalidated.
-    fn clear_dependent_provisional_results(&mut self) {
-        let head = self.stack.next_index();
+    ///
+    /// Note that we keep provisional cache entries which accessed this goal as a cycle head, but
+    /// don't depend on its value.
+    fn clear_dependent_provisional_results_for_rerun(&mut self) {
+        let rerun_index = self.stack.next_index();
         #[allow(rustc::potential_query_instability)]
         self.provisional_cache.retain(|_, entries| {
-            entries.retain(|entry| entry.heads.highest_cycle_head() != head);
+            entries.retain(|entry| {
+                let (head_index, head) = entry.heads.highest_cycle_head();
+                head_index != rerun_index || head.usages.is_empty()
+            });
             !entries.is_empty()
         });
     }
@@ -772,7 +895,7 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
         stack_entry: &StackEntry<X>,
         mut mutate_result: impl FnMut(X::Input, X::Result) -> X::Result,
     ) {
-        let popped_head = self.stack.next_index();
+        let popped_head_index = self.stack.next_index();
         #[allow(rustc::potential_query_instability)]
         self.provisional_cache.retain(|&input, entries| {
             entries.retain_mut(|entry| {
@@ -782,45 +905,65 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
                     path_from_head,
                     result,
                 } = entry;
-                let ep = if heads.highest_cycle_head() == popped_head {
+                let popped_head = if heads.highest_cycle_head_index() == popped_head_index {
                     heads.remove_highest_cycle_head()
                 } else {
                     return true;
                 };
 
                 // We're rebasing an entry `e` over a head `p`. This head
-                // has a number of own heads `h` it depends on. We need to
-                // make sure that the path kind of all paths `hph` remain the
-                // same after rebasing.
+                // has a number of own heads `h` it depends on.
                 //
-                // After rebasing the cycles `hph` will go through `e`. We need to make
-                // sure that forall possible paths `hep`, `heph` is equal to `hph.`
-                for (h, ph) in stack_entry.heads.iter() {
-                    let hp =
-                        Self::cycle_path_kind(&self.stack, stack_entry.step_kind_from_parent, h);
-
-                    // We first validate that all cycles while computing `p` would stay
-                    // the same if we were to recompute it as a nested goal of `e`.
-                    let he = hp.extend(*path_from_head);
-                    for ph in ph.iter_paths() {
-                        let hph = hp.extend(ph);
-                        for ep in ep.iter_paths() {
-                            let hep = ep.extend(he);
-                            let heph = hep.extend(ph);
-                            if hph != heph {
-                                return false;
+                // This causes our provisional result to depend on the heads
+                // of `p` to avoid moving any goal which uses this cache entry to
+                // the global cache.
+                if popped_head.usages.is_empty() {
+                    // The result of `e` does not depend on the value of `p`. This we can
+                    // keep using the result of this provisional cache entry even if evaluating
+                    // `p` as a nested goal of `e` would have a different result.
+                    for (head_index, _) in stack_entry.heads.iter() {
+                        heads.insert(head_index, PathsToNested::EMPTY, HeadUsages::default());
+                    }
+                } else {
+                    // The entry `e` actually depends on the value of `p`. We need
+                    // to make sure that the value of `p` wouldn't change even if we
+                    // were to reevaluate it as a nested goal of `e` instead. For this
+                    // we check that the path kind of all paths `hph` remain the
+                    // same after rebasing.
+                    //
+                    // After rebasing the cycles `hph` will go through `e`. We need to make
+                    // sure that forall possible paths `hep`, `heph` is equal to `hph.`
+                    let ep = popped_head.paths_to_head;
+                    for (head_index, head) in stack_entry.heads.iter() {
+                        let ph = head.paths_to_head;
+                        let hp = Self::cycle_path_kind(
+                            &self.stack,
+                            stack_entry.step_kind_from_parent,
+                            head_index,
+                        );
+                        // We first validate that all cycles while computing `p` would stay
+                        // the same if we were to recompute it as a nested goal of `e`.
+                        let he = hp.extend(*path_from_head);
+                        for ph in ph.iter_paths() {
+                            let hph = hp.extend(ph);
+                            for ep in ep.iter_paths() {
+                                let hep = ep.extend(he);
+                                let heph = hep.extend(ph);
+                                if hph != heph {
+                                    return false;
+                                }
                             }
                         }
-                    }
 
-                    // If so, all paths reached while computing `p` have to get added
-                    // the heads of `e` to make sure that rebasing `e` again also considers
-                    // them.
-                    let eph = ep.extend_with_paths(ph);
-                    heads.insert(h, eph);
+                        // If so, all paths reached while computing `p` have to get added
+                        // the heads of `e` to make sure that rebasing `e` again also considers
+                        // them.
+                        let eph = ep.extend_with_paths(ph);
+                        heads.insert(head_index, eph, head.usages);
+                    }
                 }
 
-                let Some(head) = heads.opt_highest_cycle_head() else {
+                let Some(head_index) = heads.opt_highest_cycle_head_index() else {
                     return false;
                 };
 
@@ -829,7 +972,7 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
                 *path_from_head = path_from_head.extend(Self::cycle_path_kind(
                     &self.stack,
                     stack_entry.step_kind_from_parent,
-                    head,
+                    head_index,
                 ));
                 // Mutate the result of the provisional cache entry in case we did
                 // not reach a fixpoint.
@@ -853,7 +996,7 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
         for &ProvisionalCacheEntry { encountered_overflow, ref heads, path_from_head, result } in
             entries
         {
-            let head = heads.highest_cycle_head();
+            let head_index = heads.highest_cycle_head_index();
             if encountered_overflow {
                 // This check is overly strict and very subtle. We need to make sure that if
                 // a global cache entry depends on some goal without adding it to its
@@ -865,24 +1008,26 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
                 // current goal is already part of the same cycle. This check could be
                 // improved but seems to be good enough for now.
                 let last = self.stack.last().unwrap();
-                if last.heads.opt_lowest_cycle_head().is_none_or(|lowest| lowest > head) {
+                if last.heads.opt_lowest_cycle_head_index().is_none_or(|lowest| lowest > head_index)
+                {
                     continue;
                 }
             }
 
             // A provisional cache entry is only valid if the current path from its
             // highest cycle head to the goal is the same.
-            if path_from_head == Self::cycle_path_kind(&self.stack, step_kind_from_parent, head) {
+            if path_from_head
+                == Self::cycle_path_kind(&self.stack, step_kind_from_parent, head_index)
+            {
                 Self::update_parent_goal(
                     &mut self.stack,
                     step_kind_from_parent,
                     0,
-                    heads,
+                    heads.iter(),
                     encountered_overflow,
                     UpdateParentGoalCtxt::ProvisionalCacheHit,
                 );
-                debug_assert!(self.stack[head].has_been_used.is_some());
-                debug!(?head, ?path_from_head, "provisional cache hit");
+                debug!(?head_index, ?path_from_head, "provisional cache hit");
                 return Some(result);
             }
         }
@@ -940,8 +1085,9 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
                 //
                 // We check if any of the paths taken while computing the global goal
                 // would end up with an applicable provisional cache entry.
-                let head = heads.highest_cycle_head();
-                let head_to_curr = Self::cycle_path_kind(&self.stack, step_kind_from_parent, head);
+                let head_index = heads.highest_cycle_head_index();
+                let head_to_curr =
+                    Self::cycle_path_kind(&self.stack, step_kind_from_parent, head_index);
                 let full_paths = path_from_global_entry.extend_with(head_to_curr);
                 if full_paths.contains(head_to_provisional.into()) {
                     debug!(
@@ -993,12 +1139,12 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
 
             // We don't move cycle participants to the global cache, so the
             // cycle heads are always empty.
-            let heads = Default::default();
+            let heads = iter::empty();
             Self::update_parent_goal(
                 &mut self.stack,
                 step_kind_from_parent,
                 required_depth,
-                &heads,
+                heads,
                 encountered_overflow,
                 UpdateParentGoalCtxt::Ordinary(nested_goals),
             );
@@ -1014,34 +1160,30 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
         input: X::Input,
         step_kind_from_parent: PathKind,
     ) -> Option<X::Result> {
-        let head = self.stack.find(input)?;
+        let head_index = self.stack.find(input)?;
         // We have a nested goal which directly relies on a goal deeper in the stack.
         //
         // We start by tagging all cycle participants, as that's necessary for caching.
         //
         // Finally we can return either the provisional response or the initial response
         // in case we're in the first fixpoint iteration for this goal.
-        let path_kind = Self::cycle_path_kind(&self.stack, step_kind_from_parent, head);
-        debug!(?path_kind, "encountered cycle with depth {head:?}");
-        let usage_kind = UsageKind::Single(path_kind);
-        self.stack[head].has_been_used =
-            Some(self.stack[head].has_been_used.map_or(usage_kind, |prev| prev.merge(usage_kind)));
-
-        // Subtle: when encountering a cyclic goal, we still first checked for overflow,
-        // so we have to update the reached depth.
-        let last_index = self.stack.last_index().unwrap();
-        let last = &mut self.stack[last_index];
-        last.required_depth = last.required_depth.max(1);
-
-        last.nested_goals.insert(input, step_kind_from_parent.into());
-        last.nested_goals.insert(last.input, PathsToNested::EMPTY);
-        if last_index != head {
-            last.heads.insert(head, step_kind_from_parent);
-        }
+        let path_kind = Self::cycle_path_kind(&self.stack, step_kind_from_parent, head_index);
+        debug!(?path_kind, "encountered cycle with depth {head_index:?}");
+        let mut usages = HeadUsages::default();
+        usages.add_usage(path_kind);
+        let head = CycleHead { paths_to_head: step_kind_from_parent.into(), usages };
+        Self::update_parent_goal(
+            &mut self.stack,
+            step_kind_from_parent,
+            0,
+            iter::once((head_index, head)),
+            false,
+            UpdateParentGoalCtxt::CycleOnStack(input),
+        );
 
         // Return the provisional result or, if we're in the first iteration,
         // start with no constraints.
-        if let Some(result) = self.stack[head].provisional_result {
+        if let Some(result) = self.stack[head_index].provisional_result {
             Some(result)
         } else {
             Some(D::initial_provisional_result(cx, path_kind, input))
@@ -1053,15 +1195,31 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
         &mut self,
         cx: X,
         stack_entry: &StackEntry<X>,
-        usage_kind: UsageKind,
+        usages: HeadUsages,
         result: X::Result,
     ) -> bool {
-        if let Some(prev) = stack_entry.provisional_result {
-            prev == result
-        } else if let UsageKind::Single(kind) = usage_kind {
-            D::is_initial_provisional_result(cx, kind, stack_entry.input, result)
+        let provisional_result = stack_entry.provisional_result;
+        if usages.is_empty() {
+            true
+        } else if let Some(provisional_result) = provisional_result {
+            provisional_result == result
         } else {
-            false
+            let check = |k| D::is_initial_provisional_result(cx, k, stack_entry.input, result);
+            match usages {
+                HeadUsages { inductive: _, unknown: 0, coinductive: 0, forced_ambiguity: 0 } => {
+                    check(PathKind::Inductive)
+                }
+                HeadUsages { inductive: 0, unknown: _, coinductive: 0, forced_ambiguity: 0 } => {
+                    check(PathKind::Unknown)
+                }
+                HeadUsages { inductive: 0, unknown: 0, coinductive: _, forced_ambiguity: 0 } => {
+                    check(PathKind::Coinductive)
+                }
+                HeadUsages { inductive: 0, unknown: 0, coinductive: 0, forced_ambiguity: _ } => {
+                    check(PathKind::ForcedAmbiguity)
+                }
+                _ => false,
+            }
         }
     }
 
@@ -1091,7 +1249,7 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
             // If the current goal is not the root of a cycle, we are done.
             //
             // There are no provisional cache entries which depend on this goal.
-            let Some(usage_kind) = stack_entry.has_been_used else {
+            let Some(usages) = stack_entry.usages else {
                 return EvaluationResult::finalize(stack_entry, encountered_overflow, result);
             };
 
@@ -1106,7 +1264,7 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
             // is equal to the provisional result of the previous iteration, or because
             // this was only the root of either coinductive or inductive cycles, and the
             // final result is equal to the initial response for that case.
-            if self.reached_fixpoint(cx, &stack_entry, usage_kind, result) {
+            if self.reached_fixpoint(cx, &stack_entry, usages, result) {
                 self.rebase_provisional_cache_entries(&stack_entry, |_, result| result);
                 return EvaluationResult::finalize(stack_entry, encountered_overflow, result);
             }
@@ -1144,7 +1302,7 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
 
             // Clear all provisional cache entries which depend on a previous provisional
             // result of this goal and rerun.
-            self.clear_dependent_provisional_results();
+            self.clear_dependent_provisional_results_for_rerun();
 
             debug!(?result, "fixpoint changed provisional results");
             self.stack.push(StackEntry {
@@ -1163,7 +1321,8 @@ impl<D: Delegate<Cx = X>, X: Cx> SearchGraph<D> {
                 // similar to the previous iterations when reevaluating, it's better
                 // for caching if the reevaluation also starts out with `false`.
                 encountered_overflow: false,
-                has_been_used: None,
+                usages: None,
+                candidate_usages: None,
             });
         }
     }
diff --git a/compiler/rustc_type_ir/src/search_graph/stack.rs b/compiler/rustc_type_ir/src/search_graph/stack.rs
index a58cd82b023..3fd8e2bd16e 100644
--- a/compiler/rustc_type_ir/src/search_graph/stack.rs
+++ b/compiler/rustc_type_ir/src/search_graph/stack.rs
@@ -1,9 +1,11 @@
-use std::ops::{Index, IndexMut};
+use std::ops::Index;
 
 use derive_where::derive_where;
 use rustc_index::IndexVec;
 
-use crate::search_graph::{AvailableDepth, Cx, CycleHeads, NestedGoals, PathKind, UsageKind};
+use crate::search_graph::{
+    AvailableDepth, CandidateHeadUsages, Cx, CycleHeads, HeadUsages, NestedGoals, PathKind,
+};
 
 rustc_index::newtype_index! {
     #[orderable]
@@ -26,13 +28,13 @@ pub(super) struct StackEntry<X: Cx> {
     /// The available depth of a given goal, immutable.
     pub available_depth: AvailableDepth,
 
+    /// The maximum depth required while evaluating this goal.
+    pub required_depth: usize,
+
     /// Starts out as `None` and gets set when rerunning this
     /// goal in case we encounter a cycle.
     pub provisional_result: Option<X::Result>,
 
-    /// The maximum depth required while evaluating this goal.
-    pub required_depth: usize,
-
     /// All cycle heads this goal depends on. Lazily updated and only
     /// up-to date for the top of the stack.
     pub heads: CycleHeads,
@@ -40,14 +42,27 @@ pub(super) struct StackEntry<X: Cx> {
     /// Whether evaluating this goal encountered overflow. Lazily updated.
     pub encountered_overflow: bool,
 
-    /// Whether this goal has been used as the root of a cycle. This gets
-    /// eagerly updated when encountering a cycle.
-    pub has_been_used: Option<UsageKind>,
+    /// Whether and how this goal has been used as the root of a cycle. Lazily updated.
+    pub usages: Option<HeadUsages>,
+
+    /// We want to be able to ignore head usages if they happen inside of candidates
+    /// which don't impact the result of a goal. This enables us to avoid rerunning goals
+    /// and is also used when rebasing provisional cache entries.
+    ///
+    /// To implement this, we track all usages while evaluating a candidate. If this candidate
+    /// then ends up ignored, we manually remove its usages from `usages` and `heads`.
+    pub candidate_usages: Option<CandidateHeadUsages>,
 
     /// The nested goals of this goal, see the doc comment of the type.
     pub nested_goals: NestedGoals<X>,
 }
 
+/// The stack of goals currently being computed.
+///
+/// An element is *deeper* in the stack if its index is *lower*.
+///
+/// Only the last entry of the stack is mutable. All other entries get
+/// lazily updated in `update_parent_goal`.
 #[derive_where(Default; X: Cx)]
 pub(super) struct Stack<X: Cx> {
     entries: IndexVec<StackDepth, StackEntry<X>>,
@@ -62,10 +77,6 @@ impl<X: Cx> Stack<X> {
         self.entries.len()
     }
 
-    pub(super) fn last_index(&self) -> Option<StackDepth> {
-        self.entries.last_index()
-    }
-
     pub(super) fn last(&self) -> Option<&StackEntry<X>> {
         self.entries.raw.last()
     }
@@ -74,6 +85,10 @@ impl<X: Cx> Stack<X> {
         self.entries.raw.last_mut()
     }
 
+    pub(super) fn last_mut_with_index(&mut self) -> Option<(StackDepth, &mut StackEntry<X>)> {
+        self.entries.last_index().map(|idx| (idx, &mut self.entries[idx]))
+    }
+
     pub(super) fn next_index(&self) -> StackDepth {
         self.entries.next_index()
     }
@@ -108,9 +123,3 @@ impl<X: Cx> Index<StackDepth> for Stack<X> {
         &self.entries[index]
     }
 }
-
-impl<X: Cx> IndexMut<StackDepth> for Stack<X> {
-    fn index_mut(&mut self, index: StackDepth) -> &mut Self::Output {
-        &mut self.entries[index]
-    }
-}