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-rw-r--r--bootstrap.example.toml3
-rw-r--r--compiler/rustc_attr_parsing/src/validate_attr.rs12
-rw-r--r--compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs1
-rw-r--r--compiler/rustc_borrowck/src/diagnostics/mod.rs7
-rw-r--r--compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs1
-rw-r--r--compiler/rustc_borrowck/src/lib.rs4
-rw-r--r--compiler/rustc_borrowck/src/places_conflict.rs2
-rw-r--r--compiler/rustc_borrowck/src/prefixes.rs3
-rw-r--r--compiler/rustc_borrowck/src/type_check/mod.rs9
-rw-r--r--compiler/rustc_codegen_cranelift/src/base.rs4
-rw-r--r--compiler/rustc_codegen_cranelift/src/value_and_place.rs2
-rw-r--r--compiler/rustc_codegen_llvm/src/builder/autodiff.rs9
-rw-r--r--compiler/rustc_codegen_ssa/src/back/linker.rs33
-rw-r--r--compiler/rustc_codegen_ssa/src/mir/analyze.rs4
-rw-r--r--compiler/rustc_codegen_ssa/src/mir/operand.rs5
-rw-r--r--compiler/rustc_codegen_ssa/src/mir/place.rs1
-rw-r--r--compiler/rustc_codegen_ssa/src/mir/rvalue.rs8
-rw-r--r--compiler/rustc_const_eval/src/check_consts/qualifs.rs1
-rw-r--r--compiler/rustc_const_eval/src/interpret/cast.rs2
-rw-r--r--compiler/rustc_const_eval/src/interpret/projection.rs2
-rw-r--r--compiler/rustc_error_codes/src/error_codes/E0608.md15
-rw-r--r--compiler/rustc_error_codes/src/error_codes/E0719.md14
-rw-r--r--compiler/rustc_expand/src/base.rs17
-rw-r--r--compiler/rustc_expand/src/expand.rs9
-rw-r--r--compiler/rustc_expand/src/mbe/macro_rules.rs58
-rw-r--r--compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs9
-rw-r--r--compiler/rustc_hir_analysis/src/coherence/orphan.rs10
-rw-r--r--compiler/rustc_hir_analysis/src/collect/item_bounds.rs20
-rw-r--r--compiler/rustc_hir_analysis/src/collect/predicates_of.rs18
-rw-r--r--compiler/rustc_hir_analysis/src/constrained_generic_params.rs53
-rw-r--r--compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs32
-rw-r--r--compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_trait.rs10
-rw-r--r--compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs18
-rw-r--r--compiler/rustc_hir_typeck/src/expr.rs27
-rw-r--r--compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs18
-rw-r--r--compiler/rustc_hir_typeck/src/lib.rs9
-rw-r--r--compiler/rustc_infer/src/infer/mod.rs17
-rw-r--r--compiler/rustc_middle/src/mir/pretty.rs4
-rw-r--r--compiler/rustc_middle/src/mir/statement.rs8
-rw-r--r--compiler/rustc_middle/src/mir/syntax.rs24
-rw-r--r--compiler/rustc_middle/src/mir/visit.rs6
-rw-r--r--compiler/rustc_mir_build/src/builder/expr/as_place.rs3
-rw-r--r--compiler/rustc_mir_dataflow/src/move_paths/builder.rs5
-rw-r--r--compiler/rustc_mir_transform/src/add_subtyping_projections.rs3
-rw-r--r--compiler/rustc_mir_transform/src/dataflow_const_prop.rs2
-rw-r--r--compiler/rustc_mir_transform/src/gvn.rs3
-rw-r--r--compiler/rustc_mir_transform/src/known_panics_lint.rs2
-rw-r--r--compiler/rustc_mir_transform/src/promote_consts.rs1
-rw-r--r--compiler/rustc_mir_transform/src/validate.rs24
-rw-r--r--compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs5
-rw-r--r--compiler/rustc_parse/src/parser/diagnostics.rs40
-rw-r--r--compiler/rustc_parse/src/parser/expr.rs58
-rw-r--r--compiler/rustc_public/src/mir/body.rs11
-rw-r--r--compiler/rustc_public/src/mir/visit.rs2
-rw-r--r--compiler/rustc_public/src/unstable/convert/internal.rs3
-rw-r--r--compiler/rustc_public/src/unstable/convert/stable/mir.rs2
-rw-r--r--compiler/rustc_target/src/spec/targets/wasm32_wali_linux_musl.rs13
-rw-r--r--compiler/rustc_target/src/spec/targets/wasm32_wasip1_threads.rs3
-rw-r--r--compiler/rustc_trait_selection/src/regions.rs2
-rw-r--r--compiler/rustc_type_ir/src/flags.rs1
-rw-r--r--library/alloc/src/boxed.rs31
-rw-r--r--library/core/src/slice/iter.rs69
-rw-r--r--library/coretests/tests/iter/sources.rs11
-rw-r--r--library/std/src/sys/net/hostname/mod.rs2
-rw-r--r--library/std/src/sys/thread_local/mod.rs2
-rw-r--r--library/std/src/sys/thread_local/native/eager.rs4
-rw-r--r--library/std/src/sys/thread_local/native/lazy.rs4
-rw-r--r--library/std/src/sys/thread_local/native/mod.rs12
-rw-r--r--library/std/src/sys/thread_local/no_threads.rs69
-rw-r--r--library/std/src/sys/thread_local/os.rs155
-rw-r--r--library/std/src/thread/local.rs233
-rw-r--r--library/std/src/thread/mod.rs1
-rw-r--r--library/std/tests/thread.rs2
-rw-r--r--src/bootstrap/defaults/bootstrap.dist.toml2
-rw-r--r--src/bootstrap/src/core/builder/mod.rs2
-rw-r--r--src/ci/citool/Cargo.toml2
-rw-r--r--src/ci/citool/src/main.rs4
-rw-r--r--src/ci/citool/src/utils.rs18
-rw-r--r--src/ci/citool/tests/test-jobs.yml2
-rw-r--r--src/ci/docker/host-x86_64/pr-check-1/Dockerfile1
-rw-r--r--src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile1
-rw-r--r--src/doc/rustc/src/lints/levels.md2
-rw-r--r--src/etc/lldb_providers.py5
-rw-r--r--src/librustdoc/html/highlight.rs3
-rw-r--r--src/librustdoc/html/highlight/tests.rs14
-rw-r--r--src/librustdoc/html/render/context.rs3
-rw-r--r--src/librustdoc/html/render/mod.rs2
-rw-r--r--src/librustdoc/html/render/span_map.rs68
-rw-r--r--src/librustdoc/html/sources.rs7
-rw-r--r--src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs4
-rw-r--r--src/tools/compiletest/src/directives.rs227
-rw-r--r--src/tools/compiletest/src/directives/auxiliary.rs35
-rw-r--r--src/tools/compiletest/src/directives/cfg.rs14
-rw-r--r--src/tools/compiletest/src/directives/needs.rs6
-rw-r--r--src/tools/compiletest/src/runtest/debugger.rs27
-rw-r--r--src/tools/compiletest/src/runtest/debuginfo.rs6
-rw-r--r--src/tools/miri/tests/pass/static_align.rs60
-rw-r--r--src/tools/miri/tests/pass/thread_local-panic.rs8
-rw-r--r--src/tools/miri/tests/pass/thread_local-panic.stderr5
-rw-r--r--src/tools/rust-analyzer/.github/workflows/ci.yaml10
-rw-r--r--src/tools/rust-analyzer/Cargo.lock22
-rw-r--r--src/tools/rust-analyzer/Cargo.toml1
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/Cargo.toml1
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/autoderef.rs10
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/builder.rs33
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/chalk_ext.rs14
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/consteval.rs6
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/consteval/tests.rs48
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/consteval_nextsolver.rs2
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/db.rs231
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/expr.rs8
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/match_check/pat_analysis.rs4
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/unsafe_check.rs16
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/display.rs21
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/drop.rs19
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/dyn_compatibility.rs4
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/infer.rs167
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/infer/closure.rs6
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/infer/coerce.rs56
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/infer/expr.rs47
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/infer/fallback.rs439
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/infer/path.rs23
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/infer/unify.rs458
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/inhabitedness.rs6
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/layout.rs6
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/layout/adt.rs4
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/layout/tests.rs23
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/lib.rs57
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/lower.rs443
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/lower/path.rs36
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/lower_nextsolver.rs189
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/lower_nextsolver/path.rs58
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/method_resolution.rs196
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/mir/eval.rs19
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/mir/eval/shim.rs6
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/mir/lower.rs16
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/mir/monomorphization.rs20
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/next_solver.rs2
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/next_solver/interner.rs22
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/next_solver/mapping.rs47
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/next_solver/region.rs10
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/next_solver/solver.rs6
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/next_solver/ty.rs9
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/tests/incremental.rs6
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/tests/method_resolution.rs4
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/tests/never_type.rs10
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/tests/regression.rs4
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/tests/regression/new_solver.rs56
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/tests/traits.rs14
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/traits.rs24
-rw-r--r--src/tools/rust-analyzer/crates/hir-ty/src/variance.rs19
-rw-r--r--src/tools/rust-analyzer/crates/hir/src/display.rs8
-rw-r--r--src/tools/rust-analyzer/crates/hir/src/lib.rs184
-rw-r--r--src/tools/rust-analyzer/crates/hir/src/source_analyzer.rs12
-rw-r--r--src/tools/rust-analyzer/crates/ide-assists/src/handlers/add_braces.rs33
-rw-r--r--src/tools/rust-analyzer/crates/ide-assists/src/handlers/add_missing_match_arms.rs2
-rw-r--r--src/tools/rust-analyzer/crates/ide-assists/src/handlers/apply_demorgan.rs35
-rw-r--r--src/tools/rust-analyzer/crates/ide-assists/src/handlers/bind_unused_param.rs33
-rw-r--r--src/tools/rust-analyzer/crates/ide-assists/src/handlers/convert_to_guarded_return.rs297
-rw-r--r--src/tools/rust-analyzer/crates/ide-assists/src/handlers/destructure_struct_binding.rs155
-rw-r--r--src/tools/rust-analyzer/crates/ide-assists/src/handlers/expand_rest_pattern.rs292
-rw-r--r--src/tools/rust-analyzer/crates/ide-assists/src/handlers/extract_variable.rs29
-rw-r--r--src/tools/rust-analyzer/crates/ide-assists/src/handlers/generate_default_from_enum_variant.rs46
-rw-r--r--src/tools/rust-analyzer/crates/ide-assists/src/handlers/invert_if.rs12
-rw-r--r--src/tools/rust-analyzer/crates/ide-assists/src/handlers/pull_assignment_up.rs35
-rw-r--r--src/tools/rust-analyzer/crates/ide-assists/src/handlers/remove_dbg.rs17
-rw-r--r--src/tools/rust-analyzer/crates/ide-assists/src/handlers/replace_arith_op.rs40
-rw-r--r--src/tools/rust-analyzer/crates/ide-assists/src/handlers/replace_if_let_with_match.rs24
-rw-r--r--src/tools/rust-analyzer/crates/ide-assists/src/handlers/replace_is_method_with_if_let_method.rs18
-rw-r--r--src/tools/rust-analyzer/crates/ide-assists/src/tests/generated.rs36
-rw-r--r--src/tools/rust-analyzer/crates/ide-completion/src/completions.rs4
-rw-r--r--src/tools/rust-analyzer/crates/ide-completion/src/completions/attribute.rs2
-rw-r--r--src/tools/rust-analyzer/crates/ide-completion/src/completions/attribute/cfg.rs30
-rw-r--r--src/tools/rust-analyzer/crates/ide-completion/src/completions/expr.rs3
-rw-r--r--src/tools/rust-analyzer/crates/ide-completion/src/completions/record.rs12
-rw-r--r--src/tools/rust-analyzer/crates/ide-completion/src/context.rs1
-rw-r--r--src/tools/rust-analyzer/crates/ide-completion/src/context/analysis.rs30
-rw-r--r--src/tools/rust-analyzer/crates/ide-completion/src/context/tests.rs69
-rw-r--r--src/tools/rust-analyzer/crates/ide-completion/src/render/pattern.rs1
-rw-r--r--src/tools/rust-analyzer/crates/ide-completion/src/tests.rs8
-rw-r--r--src/tools/rust-analyzer/crates/ide-completion/src/tests/attribute.rs84
-rw-r--r--src/tools/rust-analyzer/crates/ide-completion/src/tests/expression.rs132
-rw-r--r--src/tools/rust-analyzer/crates/ide-completion/src/tests/pattern.rs19
-rw-r--r--src/tools/rust-analyzer/crates/ide-completion/src/tests/special.rs25
-rw-r--r--src/tools/rust-analyzer/crates/ide-completion/src/tests/type_pos.rs18
-rw-r--r--src/tools/rust-analyzer/crates/ide-db/src/syntax_helpers/node_ext.rs5
-rw-r--r--src/tools/rust-analyzer/crates/ide-db/src/syntax_helpers/suggest_name.rs2
-rw-r--r--src/tools/rust-analyzer/crates/ide-diagnostics/src/handlers/missing_lifetime.rs12
-rw-r--r--src/tools/rust-analyzer/crates/ide-diagnostics/src/handlers/missing_unsafe.rs43
-rw-r--r--src/tools/rust-analyzer/crates/ide-diagnostics/src/handlers/unused_variables.rs82
-rw-r--r--src/tools/rust-analyzer/crates/ide/src/goto_type_definition.rs2
-rw-r--r--src/tools/rust-analyzer/crates/ide/src/hover.rs4
-rw-r--r--src/tools/rust-analyzer/crates/ide/src/hover/render.rs8
-rw-r--r--src/tools/rust-analyzer/crates/ide/src/hover/tests.rs42
-rw-r--r--src/tools/rust-analyzer/crates/ide/src/inlay_hints/bind_pat.rs2
-rw-r--r--src/tools/rust-analyzer/crates/ide/src/inlay_hints/closing_brace.rs2
-rw-r--r--src/tools/rust-analyzer/crates/ide/src/signature_help.rs2
-rw-r--r--src/tools/rust-analyzer/crates/ide/src/static_index.rs2
-rw-r--r--src/tools/rust-analyzer/crates/ide/src/syntax_highlighting/test_data/highlight_unsafe.html2
-rw-r--r--src/tools/rust-analyzer/crates/ide/src/view_memory_layout.rs10
-rw-r--r--src/tools/rust-analyzer/crates/intern/src/symbol/symbols.rs1
-rw-r--r--src/tools/rust-analyzer/crates/mbe/src/expander/transcriber.rs14
-rw-r--r--src/tools/rust-analyzer/crates/project-model/src/build_dependencies.rs11
-rw-r--r--src/tools/rust-analyzer/crates/project-model/src/cargo_workspace.rs57
-rw-r--r--src/tools/rust-analyzer/crates/rust-analyzer/src/config.rs2
-rw-r--r--src/tools/rust-analyzer/crates/rust-analyzer/src/diagnostics.rs23
-rw-r--r--src/tools/rust-analyzer/crates/rust-analyzer/src/flycheck.rs110
-rw-r--r--src/tools/rust-analyzer/crates/rust-analyzer/src/global_state.rs23
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-rw-r--r--src/tools/rust-analyzer/crates/rust-analyzer/src/main_loop.rs19
-rw-r--r--src/tools/rust-analyzer/crates/rust-analyzer/src/target_spec.rs3
-rw-r--r--src/tools/rust-analyzer/crates/stdx/src/lib.rs44
-rw-r--r--src/tools/rust-analyzer/crates/syntax/src/syntax_error.rs2
-rw-r--r--src/tools/rust-analyzer/docs/book/src/configuration_generated.md2
-rw-r--r--src/tools/rust-analyzer/editors/code/package-lock.json6
-rw-r--r--src/tools/rust-analyzer/editors/code/package.json2
-rw-r--r--src/tools/rust-analyzer/rust-version2
-rw-r--r--tests/codegen-llvm/autodiff/abi_handling.rs4
-rw-r--r--tests/codegen-llvm/autodiff/batched.rs2
-rw-r--r--tests/codegen-llvm/autodiff/scalar.rs2
-rw-r--r--tests/codegen-llvm/autodiff/sret.rs2
-rw-r--r--tests/codegen-llvm/autodiff/void_ret.rs41
-rw-r--r--tests/crashes/120016.rs14
-rw-r--r--tests/ui-fulldeps/mod_dir_path_canonicalized.rs1
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-rw-r--r--tests/ui/thread-local/no-unstable.rs17
-rw-r--r--tests/ui/thread-local/no-unstable.stderr57
-rw-r--r--tests/ui/traits/next-solver/forced-ambiguity-typenum-ice.rs60
-rw-r--r--tests/ui/type/pattern_types/const_generics.rs3
-rw-r--r--tests/ui/type/pattern_types/transmute.current.stderr (renamed from tests/ui/type/pattern_types/transmute.stderr)4
-rw-r--r--tests/ui/type/pattern_types/transmute.next.stderr21
-rw-r--r--tests/ui/type/pattern_types/transmute.rs3
-rw-r--r--tests/ui/typeck/coercion-check-for-indexing-expression-issue-40861.stderr2
280 files changed, 6334 insertions, 3398 deletions
diff --git a/bootstrap.example.toml b/bootstrap.example.toml
index 0a39c6d8f24..f623a3db002 100644
--- a/bootstrap.example.toml
+++ b/bootstrap.example.toml
@@ -476,9 +476,6 @@
 # when the stage 0 compiler is actually built from in-tree sources.
 #build.compiletest-allow-stage0 = false
 
-# Whether to use the precompiled stage0 libtest with compiletest.
-#build.compiletest-use-stage0-libtest = true
-
 # Default value for the `--extra-checks` flag of tidy.
 #
 # See `./x test tidy --help` for details.
diff --git a/compiler/rustc_attr_parsing/src/validate_attr.rs b/compiler/rustc_attr_parsing/src/validate_attr.rs
index 7a7624893bd..927417f89f8 100644
--- a/compiler/rustc_attr_parsing/src/validate_attr.rs
+++ b/compiler/rustc_attr_parsing/src/validate_attr.rs
@@ -207,10 +207,9 @@ pub fn check_attribute_safety(
             }
         }
 
-        // - Normal builtin attribute, or any non-builtin attribute
-        // - All non-builtin attributes are currently considered safe; writing `#[unsafe(..)]` is
-        //   not permitted on non-builtin attributes or normal builtin attributes
-        (Some(AttributeSafety::Normal) | None, Safety::Unsafe(unsafe_span)) => {
+        // - Normal builtin attribute
+        // - Writing `#[unsafe(..)]` is not permitted on normal builtin attributes
+        (Some(AttributeSafety::Normal), Safety::Unsafe(unsafe_span)) => {
             psess.dcx().emit_err(errors::InvalidAttrUnsafe {
                 span: unsafe_span,
                 name: attr_item.path.clone(),
@@ -224,9 +223,8 @@ pub fn check_attribute_safety(
         }
 
         // - Non-builtin attribute
-        // - No explicit `#[unsafe(..)]` written.
-        (None, Safety::Default) => {
-            // OK
+        (None, Safety::Unsafe(_) | Safety::Default) => {
+            // OK (not checked here)
         }
 
         (
diff --git a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
index efb622e2155..fa1be4cec1e 100644
--- a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
@@ -3968,7 +3968,6 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                         }
                         ProjectionElem::ConstantIndex { .. }
                         | ProjectionElem::Subslice { .. }
-                        | ProjectionElem::Subtype(_)
                         | ProjectionElem::Index(_)
                         | ProjectionElem::UnwrapUnsafeBinder(_) => kind,
                     },
diff --git a/compiler/rustc_borrowck/src/diagnostics/mod.rs b/compiler/rustc_borrowck/src/diagnostics/mod.rs
index 5642cdf87fd..e13c1c712d8 100644
--- a/compiler/rustc_borrowck/src/diagnostics/mod.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/mod.rs
@@ -402,7 +402,6 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 ProjectionElem::Downcast(..) if opt.including_downcast => return None,
                 ProjectionElem::Downcast(..) => (),
                 ProjectionElem::OpaqueCast(..) => (),
-                ProjectionElem::Subtype(..) => (),
                 ProjectionElem::UnwrapUnsafeBinder(_) => (),
                 ProjectionElem::Field(field, _ty) => {
                     // FIXME(project-rfc_2229#36): print capture precisely here.
@@ -484,9 +483,9 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                     PlaceRef { local, projection: proj_base }.ty(self.body, self.infcx.tcx)
                 }
                 ProjectionElem::Downcast(..) => place.ty(self.body, self.infcx.tcx),
-                ProjectionElem::Subtype(ty)
-                | ProjectionElem::OpaqueCast(ty)
-                | ProjectionElem::UnwrapUnsafeBinder(ty) => PlaceTy::from_ty(*ty),
+                ProjectionElem::OpaqueCast(ty) | ProjectionElem::UnwrapUnsafeBinder(ty) => {
+                    PlaceTy::from_ty(*ty)
+                }
                 ProjectionElem::Field(_, field_type) => PlaceTy::from_ty(*field_type),
             },
         };
diff --git a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
index 6d69040c711..727cf19cd8b 100644
--- a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs
@@ -192,7 +192,6 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                     [
                         ..,
                         ProjectionElem::Index(_)
-                        | ProjectionElem::Subtype(_)
                         | ProjectionElem::ConstantIndex { .. }
                         | ProjectionElem::OpaqueCast { .. }
                         | ProjectionElem::Subslice { .. }
diff --git a/compiler/rustc_borrowck/src/lib.rs b/compiler/rustc_borrowck/src/lib.rs
index 268cb47fd12..865cfd7d2e2 100644
--- a/compiler/rustc_borrowck/src/lib.rs
+++ b/compiler/rustc_borrowck/src/lib.rs
@@ -1989,10 +1989,8 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, '_, 'tcx> {
                 },
                 // `OpaqueCast`: only transmutes the type, so no moves there.
                 // `Downcast`  : only changes information about a `Place` without moving.
-                // `Subtype`   : only transmutes the type, so no moves.
                 // So it's safe to skip these.
                 ProjectionElem::OpaqueCast(_)
-                | ProjectionElem::Subtype(_)
                 | ProjectionElem::Downcast(_, _)
                 | ProjectionElem::UnwrapUnsafeBinder(_) => (),
             }
@@ -2218,7 +2216,6 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, '_, 'tcx> {
         for (place_base, elem) in place.iter_projections().rev() {
             match elem {
                 ProjectionElem::Index(_/*operand*/) |
-                ProjectionElem::Subtype(_) |
                 ProjectionElem::OpaqueCast(_) |
                 ProjectionElem::ConstantIndex { .. } |
                 // assigning to P[i] requires P to be valid.
@@ -2610,7 +2607,6 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, '_, 'tcx> {
                     | ProjectionElem::Index(..)
                     | ProjectionElem::ConstantIndex { .. }
                     | ProjectionElem::Subslice { .. }
-                    | ProjectionElem::Subtype(..)
                     | ProjectionElem::OpaqueCast { .. }
                     | ProjectionElem::Downcast(..)
                     | ProjectionElem::UnwrapUnsafeBinder(_) => {
diff --git a/compiler/rustc_borrowck/src/places_conflict.rs b/compiler/rustc_borrowck/src/places_conflict.rs
index cf3e82426e8..60676ac6b86 100644
--- a/compiler/rustc_borrowck/src/places_conflict.rs
+++ b/compiler/rustc_borrowck/src/places_conflict.rs
@@ -249,7 +249,6 @@ fn place_components_conflict<'tcx>(
                 | (ProjectionElem::ConstantIndex { .. }, _, _)
                 | (ProjectionElem::Subslice { .. }, _, _)
                 | (ProjectionElem::OpaqueCast { .. }, _, _)
-                | (ProjectionElem::Subtype(_), _, _)
                 | (ProjectionElem::Downcast { .. }, _, _)
                 | (ProjectionElem::UnwrapUnsafeBinder(_), _, _) => {
                     // Recursive case. This can still be disjoint on a
@@ -510,7 +509,6 @@ fn place_projection_conflict<'tcx>(
             | ProjectionElem::Field(..)
             | ProjectionElem::Index(..)
             | ProjectionElem::ConstantIndex { .. }
-            | ProjectionElem::Subtype(_)
             | ProjectionElem::OpaqueCast { .. }
             | ProjectionElem::Subslice { .. }
             | ProjectionElem::Downcast(..),
diff --git a/compiler/rustc_borrowck/src/prefixes.rs b/compiler/rustc_borrowck/src/prefixes.rs
index 83cca38a5c0..9e51264d8ed 100644
--- a/compiler/rustc_borrowck/src/prefixes.rs
+++ b/compiler/rustc_borrowck/src/prefixes.rs
@@ -77,9 +77,6 @@ impl<'tcx> Iterator for Prefixes<'tcx> {
                         | ProjectionElem::Index(_) => {
                             cursor = cursor_base;
                         }
-                        ProjectionElem::Subtype(..) => {
-                            panic!("Subtype projection is not allowed before borrow check")
-                        }
                         ProjectionElem::Deref => {
                             match self.kind {
                                 PrefixSet::Shallow => {
diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs
index 606d3d95d9e..781fb5ba113 100644
--- a/compiler/rustc_borrowck/src/type_check/mod.rs
+++ b/compiler/rustc_borrowck/src/type_check/mod.rs
@@ -1558,6 +1558,9 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                             ),
                         }
                     }
+                    CastKind::Subtype => {
+                        bug!("CastKind::Subtype shouldn't exist in borrowck")
+                    }
                 }
             }
 
@@ -1882,9 +1885,6 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                 )
                 .unwrap();
             }
-            ProjectionElem::Subtype(_) => {
-                bug!("ProjectionElem::Subtype shouldn't exist in borrowck")
-            }
         }
     }
 }
@@ -2412,9 +2412,6 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                 | ProjectionElem::UnwrapUnsafeBinder(_) => {
                     // other field access
                 }
-                ProjectionElem::Subtype(_) => {
-                    bug!("ProjectionElem::Subtype shouldn't exist in borrowck")
-                }
             }
         }
     }
diff --git a/compiler/rustc_codegen_cranelift/src/base.rs b/compiler/rustc_codegen_cranelift/src/base.rs
index 2cc5b82ddd3..ebf2ccf74de 100644
--- a/compiler/rustc_codegen_cranelift/src/base.rs
+++ b/compiler/rustc_codegen_cranelift/src/base.rs
@@ -789,7 +789,7 @@ fn codegen_stmt<'tcx>(fx: &mut FunctionCx<'_, '_, 'tcx>, cur_block: Block, stmt:
                     let operand = codegen_operand(fx, operand);
                     crate::unsize::coerce_unsized_into(fx, operand, lval);
                 }
-                Rvalue::Cast(CastKind::Transmute, ref operand, _to_ty) => {
+                Rvalue::Cast(CastKind::Transmute | CastKind::Subtype, ref operand, _to_ty) => {
                     let operand = codegen_operand(fx, operand);
                     lval.write_cvalue_transmute(fx, operand);
                 }
@@ -996,7 +996,7 @@ pub(crate) fn codegen_place<'tcx>(
                 cplace = cplace.place_deref(fx);
             }
             PlaceElem::OpaqueCast(ty) => bug!("encountered OpaqueCast({ty}) in codegen"),
-            PlaceElem::Subtype(ty) | PlaceElem::UnwrapUnsafeBinder(ty) => {
+            PlaceElem::UnwrapUnsafeBinder(ty) => {
                 cplace = cplace.place_transmute_type(fx, fx.monomorphize(ty));
             }
             PlaceElem::Field(field, _ty) => {
diff --git a/compiler/rustc_codegen_cranelift/src/value_and_place.rs b/compiler/rustc_codegen_cranelift/src/value_and_place.rs
index 04e10cf1708..db9b80c0f6a 100644
--- a/compiler/rustc_codegen_cranelift/src/value_and_place.rs
+++ b/compiler/rustc_codegen_cranelift/src/value_and_place.rs
@@ -660,7 +660,7 @@ impl<'tcx> CPlace<'tcx> {
         }
     }
 
-    /// Used for `ProjectionElem::Subtype`, `ty` has to be monomorphized before
+    /// Used for `ProjectionElem::UnwrapUnsafeBinder`, `ty` has to be monomorphized before
     /// passed on.
     pub(crate) fn place_transmute_type(
         self,
diff --git a/compiler/rustc_codegen_llvm/src/builder/autodiff.rs b/compiler/rustc_codegen_llvm/src/builder/autodiff.rs
index c3485f56391..4a749642265 100644
--- a/compiler/rustc_codegen_llvm/src/builder/autodiff.rs
+++ b/compiler/rustc_codegen_llvm/src/builder/autodiff.rs
@@ -378,5 +378,12 @@ pub(crate) fn generate_enzyme_call<'ll, 'tcx>(
 
     let call = builder.call(enzyme_ty, None, None, ad_fn, &args, None, None);
 
-    builder.store_to_place(call, dest.val);
+    let fn_ret_ty = builder.cx.val_ty(call);
+    if fn_ret_ty != builder.cx.type_void() && fn_ret_ty != builder.cx.type_struct(&[], false) {
+        // If we return void or an empty struct, then our caller (due to how we generated it)
+        // does not expect a return value. As such, we have no pointer (or place) into which
+        // we could store our value, and would store into an undef, which would cause UB.
+        // As such, we just ignore the return value in those cases.
+        builder.store_to_place(call, dest.val);
+    }
 }
diff --git a/compiler/rustc_codegen_ssa/src/back/linker.rs b/compiler/rustc_codegen_ssa/src/back/linker.rs
index e644a43f883..ac123143738 100644
--- a/compiler/rustc_codegen_ssa/src/back/linker.rs
+++ b/compiler/rustc_codegen_ssa/src/back/linker.rs
@@ -17,7 +17,6 @@ use rustc_middle::middle::exported_symbols::{
 use rustc_middle::ty::TyCtxt;
 use rustc_session::Session;
 use rustc_session::config::{self, CrateType, DebugInfo, LinkerPluginLto, Lto, OptLevel, Strip};
-use rustc_span::sym;
 use rustc_target::spec::{Cc, LinkOutputKind, LinkerFlavor, Lld};
 use tracing::{debug, warn};
 
@@ -1324,37 +1323,7 @@ struct WasmLd<'a> {
 
 impl<'a> WasmLd<'a> {
     fn new(cmd: Command, sess: &'a Session) -> WasmLd<'a> {
-        // If the atomics feature is enabled for wasm then we need a whole bunch
-        // of flags:
-        //
-        // * `--shared-memory` - the link won't even succeed without this, flags
-        //   the one linear memory as `shared`
-        //
-        // * `--max-memory=1G` - when specifying a shared memory this must also
-        //   be specified. We conservatively choose 1GB but users should be able
-        //   to override this with `-C link-arg`.
-        //
-        // * `--import-memory` - it doesn't make much sense for memory to be
-        //   exported in a threaded module because typically you're
-        //   sharing memory and instantiating the module multiple times. As a
-        //   result if it were exported then we'd just have no sharing.
-        //
-        // On wasm32-unknown-unknown, we also export symbols for glue code to use:
-        //    * `--export=*tls*` - when `#[thread_local]` symbols are used these
-        //      symbols are how the TLS segments are initialized and configured.
-        let mut wasm_ld = WasmLd { cmd, sess };
-        if sess.target_features.contains(&sym::atomics) {
-            wasm_ld.link_args(&["--shared-memory", "--max-memory=1073741824", "--import-memory"]);
-            if sess.target.os == "unknown" || sess.target.os == "none" {
-                wasm_ld.link_args(&[
-                    "--export=__wasm_init_tls",
-                    "--export=__tls_size",
-                    "--export=__tls_align",
-                    "--export=__tls_base",
-                ]);
-            }
-        }
-        wasm_ld
+        WasmLd { cmd, sess }
     }
 }
 
diff --git a/compiler/rustc_codegen_ssa/src/mir/analyze.rs b/compiler/rustc_codegen_ssa/src/mir/analyze.rs
index c2c023af090..45bc5451946 100644
--- a/compiler/rustc_codegen_ssa/src/mir/analyze.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/analyze.rs
@@ -150,10 +150,6 @@ impl<'a, 'b, 'tcx, Bx: BuilderMethods<'b, 'tcx>> LocalAnalyzer<'a, 'b, 'tcx, Bx>
                     {
                         layout.for_variant(self.fx.cx, vidx)
                     }
-                    mir::PlaceElem::Subtype(subtype_ty) => {
-                        let subtype_ty = self.fx.monomorphize(subtype_ty);
-                        self.fx.cx.layout_of(subtype_ty)
-                    }
                     _ => {
                         self.locals[place_ref.local] = LocalKind::Memory;
                         return;
diff --git a/compiler/rustc_codegen_ssa/src/mir/operand.rs b/compiler/rustc_codegen_ssa/src/mir/operand.rs
index d851c332980..5f7f87fc692 100644
--- a/compiler/rustc_codegen_ssa/src/mir/operand.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/operand.rs
@@ -956,11 +956,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                             let layout = o.layout.for_variant(bx.cx(), vidx);
                             o = OperandRef { val: o.val, layout }
                         }
-                        mir::PlaceElem::Subtype(subtype_ty) => {
-                            let subtype_ty = self.monomorphize(subtype_ty);
-                            let layout = self.cx.layout_of(subtype_ty);
-                            o = OperandRef { val: o.val, layout }
-                        }
                         _ => return None,
                     }
                 }
diff --git a/compiler/rustc_codegen_ssa/src/mir/place.rs b/compiler/rustc_codegen_ssa/src/mir/place.rs
index 0090be9fdef..50f56f913a5 100644
--- a/compiler/rustc_codegen_ssa/src/mir/place.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/place.rs
@@ -347,7 +347,6 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 mir::ProjectionElem::OpaqueCast(ty) => {
                     bug!("encountered OpaqueCast({ty}) in codegen")
                 }
-                mir::ProjectionElem::Subtype(ty) => cg_base.project_type(bx, self.monomorphize(ty)),
                 mir::ProjectionElem::UnwrapUnsafeBinder(ty) => {
                     cg_base.project_type(bx, self.monomorphize(ty))
                 }
diff --git a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
index 0a4b0f8d494..d629003bff5 100644
--- a/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/rvalue.rs
@@ -86,7 +86,11 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 }
             }
 
-            mir::Rvalue::Cast(mir::CastKind::Transmute, ref operand, _ty) => {
+            mir::Rvalue::Cast(
+                mir::CastKind::Transmute | mir::CastKind::Subtype,
+                ref operand,
+                _ty,
+            ) => {
                 let src = self.codegen_operand(bx, operand);
                 self.codegen_transmute(bx, src, dest);
             }
@@ -486,7 +490,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                                 bug!("Unsupported cast of {operand:?} to {cast:?}");
                             })
                     }
-                    mir::CastKind::Transmute => {
+                    mir::CastKind::Transmute | mir::CastKind::Subtype => {
                         self.codegen_transmute_operand(bx, operand, cast)
                     }
                 };
diff --git a/compiler/rustc_const_eval/src/check_consts/qualifs.rs b/compiler/rustc_const_eval/src/check_consts/qualifs.rs
index 34d1fdd8c86..8a6827bca2b 100644
--- a/compiler/rustc_const_eval/src/check_consts/qualifs.rs
+++ b/compiler/rustc_const_eval/src/check_consts/qualifs.rs
@@ -293,7 +293,6 @@ where
             ProjectionElem::Index(index) if in_local(index) => return true,
 
             ProjectionElem::Deref
-            | ProjectionElem::Subtype(_)
             | ProjectionElem::Field(_, _)
             | ProjectionElem::OpaqueCast(_)
             | ProjectionElem::ConstantIndex { .. }
diff --git a/compiler/rustc_const_eval/src/interpret/cast.rs b/compiler/rustc_const_eval/src/interpret/cast.rs
index 0075740e031..b058d4b8ad4 100644
--- a/compiler/rustc_const_eval/src/interpret/cast.rs
+++ b/compiler/rustc_const_eval/src/interpret/cast.rs
@@ -133,7 +133,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
                 }
             }
 
-            CastKind::Transmute => {
+            CastKind::Transmute | CastKind::Subtype => {
                 assert!(src.layout.is_sized());
                 assert!(dest.layout.is_sized());
                 assert_eq!(cast_ty, dest.layout.ty); // we otherwise ignore `cast_ty` enirely...
diff --git a/compiler/rustc_const_eval/src/interpret/projection.rs b/compiler/rustc_const_eval/src/interpret/projection.rs
index d05871bfc77..2fd1657f6ba 100644
--- a/compiler/rustc_const_eval/src/interpret/projection.rs
+++ b/compiler/rustc_const_eval/src/interpret/projection.rs
@@ -395,8 +395,6 @@ where
                 span_bug!(self.cur_span(), "OpaqueCast({ty}) encountered after borrowck")
             }
             UnwrapUnsafeBinder(target) => base.transmute(self.layout_of(target)?, self)?,
-            // We don't want anything happening here, this is here as a dummy.
-            Subtype(_) => base.transmute(base.layout(), self)?,
             Field(field, _) => self.project_field(base, field)?,
             Downcast(_, variant) => self.project_downcast(base, variant)?,
             Deref => self.deref_pointer(&base.to_op(self)?)?.into(),
diff --git a/compiler/rustc_error_codes/src/error_codes/E0608.md b/compiler/rustc_error_codes/src/error_codes/E0608.md
index d0ebc3a26f0..3c29484f575 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0608.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0608.md
@@ -1,5 +1,5 @@
-An attempt to use index on a type which doesn't implement the `std::ops::Index`
-trait was performed.
+Attempted to index a value whose type doesn't implement the
+`std::ops::Index` trait.
 
 Erroneous code example:
 
@@ -7,8 +7,8 @@ Erroneous code example:
 0u8[2]; // error: cannot index into a value of type `u8`
 ```
 
-To be able to index into a type it needs to implement the `std::ops::Index`
-trait. Example:
+Only values with types that implement the `std::ops::Index` trait
+can be indexed with square brackets. Example:
 
 ```
 let v: Vec<u8> = vec![0, 1, 2, 3];
@@ -16,3 +16,10 @@ let v: Vec<u8> = vec![0, 1, 2, 3];
 // The `Vec` type implements the `Index` trait so you can do:
 println!("{}", v[2]);
 ```
+
+Tuples and structs are indexed with dot (`.`), not with brackets (`[]`),
+and tuple element names are their positions:
+```ignore(pseudo code)
+// this (pseudo code) expression is true for any tuple:
+tuple == (tuple.0, tuple.1, ...)
+```
diff --git a/compiler/rustc_error_codes/src/error_codes/E0719.md b/compiler/rustc_error_codes/src/error_codes/E0719.md
index cd981db1058..6aec38b42a3 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0719.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0719.md
@@ -1,4 +1,4 @@
-An associated type value was specified more than once.
+An associated item was specified more than once in a trait object.
 
 Erroneous code example:
 
@@ -7,21 +7,15 @@ trait FooTrait {}
 trait BarTrait {}
 
 // error: associated type `Item` in trait `Iterator` is specified twice
-struct Foo<T: Iterator<Item: FooTrait, Item: BarTrait>> { f: T }
+type Foo = dyn Iterator<Item = u32, Item = u32>;
 ```
 
-`Item` in trait `Iterator` cannot be specified multiple times for struct `Foo`.
-To fix this, create a new trait that is a combination of the desired traits and
-specify the associated type with the new trait.
+To fix this, remove the duplicate specifier:
 
 Corrected example:
 
 ```
-trait FooTrait {}
-trait BarTrait {}
-trait FooBarTrait: FooTrait + BarTrait {}
-
-struct Foo<T: Iterator<Item: FooBarTrait>> { f: T } // ok!
+type Foo = dyn Iterator<Item = u32>; // ok!
 ```
 
 For more information about associated types, see [the book][bk-at]. For more
diff --git a/compiler/rustc_expand/src/base.rs b/compiler/rustc_expand/src/base.rs
index 33b712e3aed..810a5a21a05 100644
--- a/compiler/rustc_expand/src/base.rs
+++ b/compiler/rustc_expand/src/base.rs
@@ -10,7 +10,7 @@ use rustc_ast::attr::{AttributeExt, MarkedAttrs};
 use rustc_ast::token::MetaVarKind;
 use rustc_ast::tokenstream::TokenStream;
 use rustc_ast::visit::{AssocCtxt, Visitor};
-use rustc_ast::{self as ast, AttrVec, Attribute, HasAttrs, Item, NodeId, PatKind};
+use rustc_ast::{self as ast, AttrVec, Attribute, HasAttrs, Item, NodeId, PatKind, Safety};
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
 use rustc_data_structures::sync;
 use rustc_errors::{BufferedEarlyLint, DiagCtxtHandle, ErrorGuaranteed, PResult};
@@ -345,6 +345,21 @@ pub trait AttrProcMacro {
         annotation: TokenStream,
         annotated: TokenStream,
     ) -> Result<TokenStream, ErrorGuaranteed>;
+
+    // Default implementation for safe attributes; override if the attribute can be unsafe.
+    fn expand_with_safety<'cx>(
+        &self,
+        ecx: &'cx mut ExtCtxt<'_>,
+        safety: Safety,
+        span: Span,
+        annotation: TokenStream,
+        annotated: TokenStream,
+    ) -> Result<TokenStream, ErrorGuaranteed> {
+        if let Safety::Unsafe(span) = safety {
+            ecx.dcx().span_err(span, "unnecessary `unsafe` on safe attribute");
+        }
+        self.expand(ecx, span, annotation, annotated)
+    }
 }
 
 impl<F> AttrProcMacro for F
diff --git a/compiler/rustc_expand/src/expand.rs b/compiler/rustc_expand/src/expand.rs
index 172bc3d1d9f..3dfa3cdcc35 100644
--- a/compiler/rustc_expand/src/expand.rs
+++ b/compiler/rustc_expand/src/expand.rs
@@ -812,11 +812,12 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                         _ => item.to_tokens(),
                     };
                     let attr_item = attr.get_normal_item();
+                    let safety = attr_item.unsafety;
                     if let AttrArgs::Eq { .. } = attr_item.args {
                         self.cx.dcx().emit_err(UnsupportedKeyValue { span });
                     }
                     let inner_tokens = attr_item.args.inner_tokens();
-                    match expander.expand(self.cx, span, inner_tokens, tokens) {
+                    match expander.expand_with_safety(self.cx, safety, span, inner_tokens, tokens) {
                         Ok(tok_result) => {
                             let fragment = self.parse_ast_fragment(
                                 tok_result,
@@ -840,6 +841,9 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                         Err(guar) => return ExpandResult::Ready(fragment_kind.dummy(span, guar)),
                     }
                 } else if let SyntaxExtensionKind::LegacyAttr(expander) = ext {
+                    // `LegacyAttr` is only used for builtin attribute macros, which have their
+                    // safety checked by `check_builtin_meta_item`, so we don't need to check
+                    // `unsafety` here.
                     match validate_attr::parse_meta(&self.cx.sess.psess, &attr) {
                         Ok(meta) => {
                             let item_clone = macro_stats.then(|| item.clone());
@@ -882,6 +886,9 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                         }
                     }
                 } else if let SyntaxExtensionKind::NonMacroAttr = ext {
+                    if let ast::Safety::Unsafe(span) = attr.get_normal_item().unsafety {
+                        self.cx.dcx().span_err(span, "unnecessary `unsafe` on safe attribute");
+                    }
                     // `-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));
diff --git a/compiler/rustc_expand/src/mbe/macro_rules.rs b/compiler/rustc_expand/src/mbe/macro_rules.rs
index d4504ba720e..c548cea537f 100644
--- a/compiler/rustc_expand/src/mbe/macro_rules.rs
+++ b/compiler/rustc_expand/src/mbe/macro_rules.rs
@@ -8,7 +8,7 @@ use rustc_ast::token::NtPatKind::*;
 use rustc_ast::token::TokenKind::*;
 use rustc_ast::token::{self, Delimiter, NonterminalKind, Token, TokenKind};
 use rustc_ast::tokenstream::{self, DelimSpan, TokenStream};
-use rustc_ast::{self as ast, DUMMY_NODE_ID, NodeId};
+use rustc_ast::{self as ast, DUMMY_NODE_ID, NodeId, Safety};
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
 use rustc_errors::{Applicability, Diag, ErrorGuaranteed, MultiSpan};
@@ -131,6 +131,7 @@ pub(super) enum MacroRule {
     Func { lhs: Vec<MatcherLoc>, lhs_span: Span, rhs: mbe::TokenTree },
     /// An attr rule, for use with `#[m]`
     Attr {
+        unsafe_rule: bool,
         args: Vec<MatcherLoc>,
         args_span: Span,
         body: Vec<MatcherLoc>,
@@ -248,7 +249,18 @@ impl TTMacroExpander for MacroRulesMacroExpander {
 impl AttrProcMacro for MacroRulesMacroExpander {
     fn expand(
         &self,
+        _cx: &mut ExtCtxt<'_>,
+        _sp: Span,
+        _args: TokenStream,
+        _body: TokenStream,
+    ) -> Result<TokenStream, ErrorGuaranteed> {
+        unreachable!("`expand` called on `MacroRulesMacroExpander`, expected `expand_with_safety`")
+    }
+
+    fn expand_with_safety(
+        &self,
         cx: &mut ExtCtxt<'_>,
+        safety: Safety,
         sp: Span,
         args: TokenStream,
         body: TokenStream,
@@ -260,6 +272,7 @@ impl AttrProcMacro for MacroRulesMacroExpander {
             self.node_id,
             self.name,
             self.transparency,
+            safety,
             args,
             body,
             &self.rules,
@@ -408,6 +421,7 @@ fn expand_macro_attr(
     node_id: NodeId,
     name: Ident,
     transparency: Transparency,
+    safety: Safety,
     args: TokenStream,
     body: TokenStream,
     rules: &[MacroRule],
@@ -429,13 +443,26 @@ fn expand_macro_attr(
     // Track nothing for the best performance.
     match try_match_macro_attr(psess, name, &args, &body, rules, &mut NoopTracker) {
         Ok((i, rule, named_matches)) => {
-            let MacroRule::Attr { rhs, .. } = rule else {
+            let MacroRule::Attr { rhs, unsafe_rule, .. } = rule else {
                 panic!("try_macro_match_attr returned non-attr rule");
             };
             let mbe::TokenTree::Delimited(rhs_span, _, rhs) = rhs else {
                 cx.dcx().span_bug(sp, "malformed macro rhs");
             };
 
+            match (safety, unsafe_rule) {
+                (Safety::Default, false) | (Safety::Unsafe(_), true) => {}
+                (Safety::Default, true) => {
+                    cx.dcx().span_err(sp, "unsafe attribute invocation requires `unsafe`");
+                }
+                (Safety::Unsafe(span), false) => {
+                    cx.dcx().span_err(span, "unnecessary `unsafe` on safe attribute invocation");
+                }
+                (Safety::Safe(span), _) => {
+                    cx.dcx().span_bug(span, "unexpected `safe` keyword");
+                }
+            }
+
             let id = cx.current_expansion.id;
             let tts = transcribe(psess, &named_matches, rhs, *rhs_span, transparency, id)
                 .map_err(|e| e.emit())?;
@@ -681,6 +708,11 @@ pub fn compile_declarative_macro(
     let mut rules = Vec::new();
 
     while p.token != token::Eof {
+        let unsafe_rule = p.eat_keyword_noexpect(kw::Unsafe);
+        let unsafe_keyword_span = p.prev_token.span;
+        if unsafe_rule && let Some(guar) = check_no_eof(sess, &p, "expected `attr`") {
+            return dummy_syn_ext(guar);
+        }
         let (args, is_derive) = if p.eat_keyword_noexpect(sym::attr) {
             kinds |= MacroKinds::ATTR;
             if !features.macro_attr() {
@@ -705,6 +737,10 @@ pub fn compile_declarative_macro(
                 feature_err(sess, sym::macro_derive, span, "`macro_rules!` derives are unstable")
                     .emit();
             }
+            if unsafe_rule {
+                sess.dcx()
+                    .span_err(unsafe_keyword_span, "`unsafe` is only supported on `attr` rules");
+            }
             if let Some(guar) = check_no_eof(sess, &p, "expected `()` after `derive`") {
                 return dummy_syn_ext(guar);
             }
@@ -730,6 +766,10 @@ pub fn compile_declarative_macro(
             (None, true)
         } else {
             kinds |= MacroKinds::BANG;
+            if unsafe_rule {
+                sess.dcx()
+                    .span_err(unsafe_keyword_span, "`unsafe` is only supported on `attr` rules");
+            }
             (None, false)
         };
         let lhs_tt = p.parse_token_tree();
@@ -741,10 +781,10 @@ pub fn compile_declarative_macro(
         if let Some(guar) = check_no_eof(sess, &p, "expected right-hand side of macro rule") {
             return dummy_syn_ext(guar);
         }
-        let rhs_tt = p.parse_token_tree();
-        let rhs_tt = parse_one_tt(rhs_tt, RulePart::Body, sess, node_id, features, edition);
-        check_emission(check_rhs(sess, &rhs_tt));
-        check_emission(check_meta_variables(&sess.psess, node_id, args.as_ref(), &lhs_tt, &rhs_tt));
+        let rhs = p.parse_token_tree();
+        let rhs = parse_one_tt(rhs, RulePart::Body, sess, node_id, features, edition);
+        check_emission(check_rhs(sess, &rhs));
+        check_emission(check_meta_variables(&sess.psess, node_id, args.as_ref(), &lhs_tt, &rhs));
         let lhs_span = lhs_tt.span();
         // Convert the lhs into `MatcherLoc` form, which is better for doing the
         // actual matching.
@@ -760,11 +800,11 @@ 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 });
+            rules.push(MacroRule::Attr { unsafe_rule, args, args_span, body: lhs, body_span, rhs });
         } else if is_derive {
-            rules.push(MacroRule::Derive { body: lhs, body_span: lhs_span, rhs: rhs_tt });
+            rules.push(MacroRule::Derive { body: lhs, body_span: lhs_span, rhs });
         } else {
-            rules.push(MacroRule::Func { lhs, lhs_span, rhs: rhs_tt });
+            rules.push(MacroRule::Func { lhs, lhs_span, rhs });
         }
         if p.token == token::Eof {
             break;
diff --git a/compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs b/compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs
index 38ae7852ca9..b069a74bf5a 100644
--- a/compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs
+++ b/compiler/rustc_hir_analysis/src/coherence/inherent_impls.rs
@@ -195,11 +195,10 @@ impl<'tcx> InherentCollect<'tcx> {
             | ty::Closure(..)
             | ty::CoroutineClosure(..)
             | ty::Coroutine(..)
-            | ty::CoroutineWitness(..)
-            | ty::Alias(ty::Free, _)
-            | ty::Bound(..)
-            | ty::Placeholder(_)
-            | ty::Infer(_) => {
+            | ty::CoroutineWitness(..) => {
+                Err(self.tcx.dcx().delayed_bug("cannot define inherent `impl` for closure types"))
+            }
+            ty::Alias(ty::Free, _) | ty::Bound(..) | ty::Placeholder(_) | ty::Infer(_) => {
                 bug!("unexpected impl self type of impl: {:?} {:?}", id, self_ty);
             }
             // We could bail out here, but that will silence other useful errors.
diff --git a/compiler/rustc_hir_analysis/src/coherence/orphan.rs b/compiler/rustc_hir_analysis/src/coherence/orphan.rs
index 621431ae234..5a61248cab8 100644
--- a/compiler/rustc_hir_analysis/src/coherence/orphan.rs
+++ b/compiler/rustc_hir_analysis/src/coherence/orphan.rs
@@ -230,10 +230,12 @@ pub(crate) fn orphan_check_impl(
             ty::Closure(..)
             | ty::CoroutineClosure(..)
             | ty::Coroutine(..)
-            | ty::CoroutineWitness(..)
-            | ty::Bound(..)
-            | ty::Placeholder(..)
-            | ty::Infer(..) => {
+            | ty::CoroutineWitness(..) => {
+                return Err(tcx
+                    .dcx()
+                    .delayed_bug("cannot define inherent `impl` for closure types"));
+            }
+            ty::Bound(..) | ty::Placeholder(..) | ty::Infer(..) => {
                 let sp = tcx.def_span(impl_def_id);
                 span_bug!(sp, "weird self type for autotrait impl")
             }
diff --git a/compiler/rustc_hir_analysis/src/collect/item_bounds.rs b/compiler/rustc_hir_analysis/src/collect/item_bounds.rs
index ba54fa8cc0d..9841fafc82c 100644
--- a/compiler/rustc_hir_analysis/src/collect/item_bounds.rs
+++ b/compiler/rustc_hir_analysis/src/collect/item_bounds.rs
@@ -12,7 +12,7 @@ use tracing::{debug, instrument};
 
 use super::ItemCtxt;
 use super::predicates_of::assert_only_contains_predicates_from;
-use crate::hir_ty_lowering::{HirTyLowerer, PredicateFilter};
+use crate::hir_ty_lowering::{HirTyLowerer, OverlappingAsssocItemConstraints, PredicateFilter};
 
 /// For associated types we include both bounds written on the type
 /// (`type X: Trait`) and predicates from the trait: `where Self::X: Trait`.
@@ -37,7 +37,14 @@ fn associated_type_bounds<'tcx>(
 
         let icx = ItemCtxt::new(tcx, assoc_item_def_id);
         let mut bounds = Vec::new();
-        icx.lowerer().lower_bounds(item_ty, hir_bounds, &mut bounds, ty::List::empty(), filter);
+        icx.lowerer().lower_bounds(
+            item_ty,
+            hir_bounds,
+            &mut bounds,
+            ty::List::empty(),
+            filter,
+            OverlappingAsssocItemConstraints::Allowed,
+        );
 
         match filter {
             PredicateFilter::All
@@ -347,7 +354,14 @@ fn opaque_type_bounds<'tcx>(
     ty::print::with_reduced_queries!({
         let icx = ItemCtxt::new(tcx, opaque_def_id);
         let mut bounds = Vec::new();
-        icx.lowerer().lower_bounds(item_ty, hir_bounds, &mut bounds, ty::List::empty(), filter);
+        icx.lowerer().lower_bounds(
+            item_ty,
+            hir_bounds,
+            &mut bounds,
+            ty::List::empty(),
+            filter,
+            OverlappingAsssocItemConstraints::Allowed,
+        );
         // Implicit bounds are added to opaque types unless a `?Trait` bound is found
         match filter {
             PredicateFilter::All
diff --git a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
index dd3590f9ac5..ffdf2a2f4c0 100644
--- a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
@@ -18,7 +18,9 @@ use super::item_bounds::explicit_item_bounds_with_filter;
 use crate::collect::ItemCtxt;
 use crate::constrained_generic_params as cgp;
 use crate::delegation::inherit_predicates_for_delegation_item;
-use crate::hir_ty_lowering::{HirTyLowerer, PredicateFilter, RegionInferReason};
+use crate::hir_ty_lowering::{
+    HirTyLowerer, OverlappingAsssocItemConstraints, PredicateFilter, RegionInferReason,
+};
 
 /// Returns a list of all type predicates (explicit and implicit) for the definition with
 /// ID `def_id`. This includes all predicates returned by `explicit_predicates_of`, plus
@@ -187,6 +189,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
             &mut bounds,
             ty::List::empty(),
             PredicateFilter::All,
+            OverlappingAsssocItemConstraints::Allowed,
         );
         icx.lowerer().add_sizedness_bounds(
             &mut bounds,
@@ -289,6 +292,7 @@ fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Gen
                     &mut bounds,
                     bound_vars,
                     PredicateFilter::All,
+                    OverlappingAsssocItemConstraints::Allowed,
                 );
                 predicates.extend(bounds);
             }
@@ -659,7 +663,14 @@ pub(super) fn implied_predicates_with_filter<'tcx>(
 
     let self_param_ty = tcx.types.self_param;
     let mut bounds = Vec::new();
-    icx.lowerer().lower_bounds(self_param_ty, superbounds, &mut bounds, ty::List::empty(), filter);
+    icx.lowerer().lower_bounds(
+        self_param_ty,
+        superbounds,
+        &mut bounds,
+        ty::List::empty(),
+        filter,
+        OverlappingAsssocItemConstraints::Allowed,
+    );
     match filter {
         PredicateFilter::All
         | PredicateFilter::SelfOnly
@@ -984,6 +995,7 @@ impl<'tcx> ItemCtxt<'tcx> {
                 &mut bounds,
                 bound_vars,
                 filter,
+                OverlappingAsssocItemConstraints::Allowed,
             );
         }
 
@@ -1063,6 +1075,7 @@ pub(super) fn const_conditions<'tcx>(
                     &mut bounds,
                     bound_vars,
                     PredicateFilter::ConstIfConst,
+                    OverlappingAsssocItemConstraints::Allowed,
                 );
             }
             _ => {}
@@ -1083,6 +1096,7 @@ pub(super) fn const_conditions<'tcx>(
             &mut bounds,
             ty::List::empty(),
             PredicateFilter::ConstIfConst,
+            OverlappingAsssocItemConstraints::Allowed,
         );
     }
 
diff --git a/compiler/rustc_hir_analysis/src/constrained_generic_params.rs b/compiler/rustc_hir_analysis/src/constrained_generic_params.rs
index 2a633810cd7..f8d0ea3e7bf 100644
--- a/compiler/rustc_hir_analysis/src/constrained_generic_params.rs
+++ b/compiler/rustc_hir_analysis/src/constrained_generic_params.rs
@@ -167,15 +167,20 @@ pub(crate) fn setup_constraining_predicates<'tcx>(
     // which is `O(nt)` where `t` is the depth of type-parameter constraints,
     // remembering that `t` should be less than 7 in practice.
     //
+    // FIXME(hkBst): the big-O bound above would be accurate for the number
+    // of calls to `parameters_for`, which itself is some O(complexity of type).
+    // That would make this potentially cubic instead of merely quadratic...
+    // ...unless we cache those `parameters_for` calls.
+    //
     // Basically, I iterate over all projections and swap every
     // "ready" projection to the start of the list, such that
     // all of the projections before `i` are topologically sorted
     // and constrain all the parameters in `input_parameters`.
     //
-    // In the example, `input_parameters` starts by containing `U` - which
-    // is constrained by the trait-ref - and so on the first pass we
+    // In the first example, `input_parameters` starts by containing `U`,
+    // which is constrained by the self type `U`. Then, on the first pass we
     // observe that `<U as Iterator>::Item = T` is a "ready" projection that
-    // constrains `T` and swap it to front. As it is the sole projection,
+    // constrains `T` and swap it to the front. As it is the sole projection,
     // no more swaps can take place afterwards, with the result being
     //   * <U as Iterator>::Item = T
     //   * T: Debug
@@ -193,33 +198,25 @@ pub(crate) fn setup_constraining_predicates<'tcx>(
         for j in i..predicates.len() {
             // Note that we don't have to care about binders here,
             // as the impl trait ref never contains any late-bound regions.
-            if let ty::ClauseKind::Projection(projection) = predicates[j].0.kind().skip_binder() {
-                // Special case: watch out for some kind of sneaky attempt
-                // to project out an associated type defined by this very
-                // trait.
-                let unbound_trait_ref = projection.projection_term.trait_ref(tcx);
-                if Some(unbound_trait_ref) == impl_trait_ref {
-                    continue;
-                }
-
-                // A projection depends on its input types and determines its output
-                // type. For example, if we have
-                //     `<<T as Bar>::Baz as Iterator>::Output = <U as Iterator>::Output`
-                // Then the projection only applies if `T` is known, but it still
-                // does not determine `U`.
-                let inputs = parameters_for(tcx, projection.projection_term, true);
-                let relies_only_on_inputs = inputs.iter().all(|p| input_parameters.contains(p));
-                if !relies_only_on_inputs {
-                    continue;
-                }
+            if let ty::ClauseKind::Projection(projection) = predicates[j].0.kind().skip_binder() &&
+
+            // Special case: watch out for some kind of sneaky attempt to
+            // project out an associated type defined by this very trait.
+            !impl_trait_ref.is_some_and(|t| t == projection.projection_term.trait_ref(tcx)) &&
+
+            // A projection depends on its input types and determines its output
+            // type. For example, if we have
+            //     `<<T as Bar>::Baz as Iterator>::Output = <U as Iterator>::Output`
+            // then the projection only applies if `T` is known, but it still
+            // does not determine `U`.
+                parameters_for(tcx, projection.projection_term, true).iter().all(|p| input_parameters.contains(p))
+            {
                 input_parameters.extend(parameters_for(tcx, projection.term, false));
-            } else {
-                continue;
+
+                predicates.swap(i, j);
+                i += 1;
+                changed = true;
             }
-            // fancy control flow to bypass borrow checker
-            predicates.swap(i, j);
-            i += 1;
-            changed = true;
         }
         debug!(
             "setup_constraining_predicates: predicates={:?} \
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs
index 99dc8e6e522..8682fdc5494 100644
--- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs
+++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs
@@ -21,7 +21,8 @@ use tracing::{debug, instrument};
 use super::errors::GenericsArgsErrExtend;
 use crate::errors;
 use crate::hir_ty_lowering::{
-    AssocItemQSelf, FeedConstTy, HirTyLowerer, PredicateFilter, RegionInferReason,
+    AssocItemQSelf, FeedConstTy, HirTyLowerer, OverlappingAsssocItemConstraints, PredicateFilter,
+    RegionInferReason,
 };
 
 #[derive(Debug, Default)]
@@ -338,6 +339,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         bounds: &mut Vec<(ty::Clause<'tcx>, Span)>,
         bound_vars: &'tcx ty::List<ty::BoundVariableKind>,
         predicate_filter: PredicateFilter,
+        overlapping_assoc_constraints: OverlappingAsssocItemConstraints,
     ) where
         'tcx: 'hir,
     {
@@ -362,6 +364,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                         param_ty,
                         bounds,
                         predicate_filter,
+                        overlapping_assoc_constraints,
                     );
                 }
                 hir::GenericBound::Outlives(lifetime) => {
@@ -402,7 +405,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         trait_ref: ty::PolyTraitRef<'tcx>,
         constraint: &hir::AssocItemConstraint<'tcx>,
         bounds: &mut Vec<(ty::Clause<'tcx>, Span)>,
-        duplicates: &mut FxIndexMap<DefId, Span>,
+        duplicates: Option<&mut FxIndexMap<DefId, Span>>,
         path_span: Span,
         predicate_filter: PredicateFilter,
     ) -> Result<(), ErrorGuaranteed> {
@@ -458,17 +461,19 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             )
             .expect("failed to find associated item");
 
-        duplicates
-            .entry(assoc_item.def_id)
-            .and_modify(|prev_span| {
-                self.dcx().emit_err(errors::ValueOfAssociatedStructAlreadySpecified {
-                    span: constraint.span,
-                    prev_span: *prev_span,
-                    item_name: constraint.ident,
-                    def_path: tcx.def_path_str(assoc_item.container_id(tcx)),
-                });
-            })
-            .or_insert(constraint.span);
+        if let Some(duplicates) = duplicates {
+            duplicates
+                .entry(assoc_item.def_id)
+                .and_modify(|prev_span| {
+                    self.dcx().emit_err(errors::ValueOfAssociatedStructAlreadySpecified {
+                        span: constraint.span,
+                        prev_span: *prev_span,
+                        item_name: constraint.ident,
+                        def_path: tcx.def_path_str(assoc_item.container_id(tcx)),
+                    });
+                })
+                .or_insert(constraint.span);
+        }
 
         let projection_term = if let ty::AssocTag::Fn = assoc_tag {
             let bound_vars = tcx.late_bound_vars(constraint.hir_id);
@@ -600,6 +605,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                             bounds,
                             projection_ty.bound_vars(),
                             predicate_filter,
+                            OverlappingAsssocItemConstraints::Allowed,
                         );
                     }
                     PredicateFilter::SelfOnly
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_trait.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_trait.rs
index c248cd7fec2..c0b13773089 100644
--- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_trait.rs
+++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_trait.rs
@@ -23,7 +23,9 @@ use tracing::{debug, instrument};
 
 use super::HirTyLowerer;
 use crate::errors::SelfInTypeAlias;
-use crate::hir_ty_lowering::{GenericArgCountMismatch, PredicateFilter, RegionInferReason};
+use crate::hir_ty_lowering::{
+    GenericArgCountMismatch, OverlappingAsssocItemConstraints, PredicateFilter, RegionInferReason,
+};
 
 impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
     /// Lower a trait object type from the HIR to our internal notion of a type.
@@ -60,6 +62,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 dummy_self,
                 &mut user_written_bounds,
                 PredicateFilter::SelfOnly,
+                OverlappingAsssocItemConstraints::Forbidden,
             );
             if let Err(GenericArgCountMismatch { invalid_args, .. }) = result.correct {
                 potential_assoc_types.extend(invalid_args);
@@ -157,10 +160,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 self.dcx()
                     .struct_span_err(
                         span,
-                        format!(
-                            "conflicting associated type bounds for `{item}` when \
-                            expanding trait alias"
-                        ),
+                        format!("conflicting associated type bounds for `{item}`"),
                     )
                     .with_span_label(
                         old_proj_span,
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
index 9b198d04454..eb660804c2b 100644
--- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
+++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
@@ -332,6 +332,15 @@ pub(crate) enum GenericArgPosition {
     MethodCall,
 }
 
+/// Whether to allow duplicate associated iten constraints in a trait ref, e.g.
+/// `Trait<Assoc = Ty, Assoc = Ty>`. This is forbidden in `dyn Trait<...>`
+/// but allowed everywhere else.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub(crate) enum OverlappingAsssocItemConstraints {
+    Allowed,
+    Forbidden,
+}
+
 /// A marker denoting that the generic arguments that were
 /// provided did not match the respective generic parameters.
 #[derive(Clone, Debug)]
@@ -752,6 +761,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         self_ty: Ty<'tcx>,
         bounds: &mut Vec<(ty::Clause<'tcx>, Span)>,
         predicate_filter: PredicateFilter,
+        overlapping_assoc_item_constraints: OverlappingAsssocItemConstraints,
     ) -> GenericArgCountResult {
         let tcx = self.tcx();
 
@@ -908,7 +918,10 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             }
         }
 
-        let mut dup_constraints = FxIndexMap::default();
+        let mut dup_constraints = (overlapping_assoc_item_constraints
+            == OverlappingAsssocItemConstraints::Forbidden)
+            .then_some(FxIndexMap::default());
+
         for constraint in trait_segment.args().constraints {
             // Don't register any associated item constraints for negative bounds,
             // since we should have emitted an error for them earlier, and they
@@ -927,7 +940,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 poly_trait_ref,
                 constraint,
                 bounds,
-                &mut dup_constraints,
+                dup_constraints.as_mut(),
                 constraint.span,
                 predicate_filter,
             );
@@ -2484,6 +2497,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                     &mut bounds,
                     ty::List::empty(),
                     PredicateFilter::All,
+                    OverlappingAsssocItemConstraints::Allowed,
                 );
                 self.add_sizedness_bounds(
                     &mut bounds,
diff --git a/compiler/rustc_hir_typeck/src/expr.rs b/compiler/rustc_hir_typeck/src/expr.rs
index d1ce0afddf9..f9cdc923670 100644
--- a/compiler/rustc_hir_typeck/src/expr.rs
+++ b/compiler/rustc_hir_typeck/src/expr.rs
@@ -3551,35 +3551,20 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     );
                     // Try to give some advice about indexing tuples.
                     if let ty::Tuple(types) = base_t.kind() {
-                        let mut needs_note = true;
-                        // If the index is an integer, we can show the actual
-                        // fixed expression:
+                        err.help(
+                            "tuples are indexed with a dot and a literal index: `tuple.0`, `tuple.1`, etc.",
+                        );
+                        // If index is an unsuffixed integer, show the fixed expression:
                         if let ExprKind::Lit(lit) = idx.kind
                             && let ast::LitKind::Int(i, ast::LitIntType::Unsuffixed) = lit.node
-                            && i.get()
-                                < types
-                                    .len()
-                                    .try_into()
-                                    .expect("expected tuple index to be < usize length")
+                            && i.get() < types.len().try_into().expect("tuple length fits in u128")
                         {
                             err.span_suggestion(
                                 brackets_span,
-                                "to access tuple elements, use",
+                                format!("to access tuple element `{i}`, use"),
                                 format!(".{i}"),
                                 Applicability::MachineApplicable,
                             );
-                            needs_note = false;
-                        } else if let ExprKind::Path(..) = idx.peel_borrows().kind {
-                            err.span_label(
-                                idx.span,
-                                "cannot access tuple elements at a variable index",
-                            );
-                        }
-                        if needs_note {
-                            err.help(
-                                "to access tuple elements, use tuple indexing \
-                                        syntax (e.g., `tuple.0`)",
-                            );
                         }
                     }
 
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
index 833ce433d56..35253e4c291 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs
@@ -611,19 +611,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         typeck_results.rvalue_scopes = rvalue_scopes;
     }
 
-    /// Unify the inference variables corresponding to coroutine witnesses, and save all the
-    /// predicates that were stalled on those inference variables.
-    ///
-    /// This process allows to conservatively save all predicates that do depend on the coroutine
-    /// interior types, for later processing by `check_coroutine_obligations`.
-    ///
-    /// We must not attempt to select obligations after this method has run, or risk query cycle
-    /// ICE.
+    /// Drain all obligations that are stalled on coroutines defined in this body.
     #[instrument(level = "debug", skip(self))]
-    pub(crate) fn resolve_coroutine_interiors(&self) {
-        // Try selecting all obligations that are not blocked on inference variables.
-        // Once we start unifying coroutine witnesses, trying to select obligations on them will
-        // trigger query cycle ICEs, as doing so requires MIR.
+    pub(crate) fn drain_stalled_coroutine_obligations(&self) {
+        // Make as much inference progress as possible before
+        // draining the stalled coroutine obligations as this may
+        // change obligations from being stalled on infer vars to
+        // being stalled on a coroutine.
         self.select_obligations_where_possible(|_| {});
 
         let ty::TypingMode::Analysis { defining_opaque_types_and_generators } = self.typing_mode()
diff --git a/compiler/rustc_hir_typeck/src/lib.rs b/compiler/rustc_hir_typeck/src/lib.rs
index acc0481e457..9f5a85b6926 100644
--- a/compiler/rustc_hir_typeck/src/lib.rs
+++ b/compiler/rustc_hir_typeck/src/lib.rs
@@ -243,18 +243,15 @@ fn typeck_with_inspect<'tcx>(
 
     debug!(pending_obligations = ?fcx.fulfillment_cx.borrow().pending_obligations());
 
-    // This must be the last thing before `report_ambiguity_errors`.
-    fcx.resolve_coroutine_interiors();
-
-    debug!(pending_obligations = ?fcx.fulfillment_cx.borrow().pending_obligations());
-
     // 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(|_| {});
+    // This must be the last thing before `report_ambiguity_errors` below except `select_obligations_where_possible`.
+    // So don't put anything after this.
+    fcx.drain_stalled_coroutine_obligations();
     if fcx.infcx.tainted_by_errors().is_none() {
         fcx.report_ambiguity_errors();
     }
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index c9fc124d3bf..f3ebfde06ab 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -131,23 +131,6 @@ pub struct InferCtxtInner<'tcx> {
     /// `$0: 'static`. This will get checked later by regionck. (We
     /// can't generally check these things right away because we have
     /// to wait until types are resolved.)
-    ///
-    /// These are stored in a map keyed to the id of the innermost
-    /// enclosing fn body / static initializer expression. This is
-    /// because the location where the obligation was incurred can be
-    /// relevant with respect to which sublifetime assumptions are in
-    /// place. The reason that we store under the fn-id, and not
-    /// something more fine-grained, is so that it is easier for
-    /// regionck to be sure that it has found *all* the region
-    /// obligations (otherwise, it's easy to fail to walk to a
-    /// particular node-id).
-    ///
-    /// Before running `resolve_regions_and_report_errors`, the creator
-    /// of the inference context is expected to invoke
-    /// [`InferCtxt::process_registered_region_obligations`]
-    /// for each body-id in this map, which will process the
-    /// obligations within. This is expected to be done 'late enough'
-    /// that all type inference variables have been bound and so forth.
     region_obligations: Vec<TypeOutlivesConstraint<'tcx>>,
 
     /// The outlives bounds that we assume must hold about placeholders that
diff --git a/compiler/rustc_middle/src/mir/pretty.rs b/compiler/rustc_middle/src/mir/pretty.rs
index 96148fd5b92..350d75c2ee7 100644
--- a/compiler/rustc_middle/src/mir/pretty.rs
+++ b/compiler/rustc_middle/src/mir/pretty.rs
@@ -1274,7 +1274,6 @@ fn pre_fmt_projection(projection: &[PlaceElem<'_>], fmt: &mut Formatter<'_>) ->
     for &elem in projection.iter().rev() {
         match elem {
             ProjectionElem::OpaqueCast(_)
-            | ProjectionElem::Subtype(_)
             | ProjectionElem::Downcast(_, _)
             | ProjectionElem::Field(_, _) => {
                 write!(fmt, "(")?;
@@ -1300,9 +1299,6 @@ fn post_fmt_projection(projection: &[PlaceElem<'_>], fmt: &mut Formatter<'_>) ->
             ProjectionElem::OpaqueCast(ty) => {
                 write!(fmt, " as {ty})")?;
             }
-            ProjectionElem::Subtype(ty) => {
-                write!(fmt, " as subtype {ty})")?;
-            }
             ProjectionElem::Downcast(Some(name), _index) => {
                 write!(fmt, " as {name})")?;
             }
diff --git a/compiler/rustc_middle/src/mir/statement.rs b/compiler/rustc_middle/src/mir/statement.rs
index 28294b47e90..e009fe05b53 100644
--- a/compiler/rustc_middle/src/mir/statement.rs
+++ b/compiler/rustc_middle/src/mir/statement.rs
@@ -222,7 +222,6 @@ impl<'tcx> PlaceTy<'tcx> {
                 fty,
             )),
             ProjectionElem::OpaqueCast(ty) => PlaceTy::from_ty(handle_opaque_cast_and_subtype(ty)),
-            ProjectionElem::Subtype(ty) => PlaceTy::from_ty(handle_opaque_cast_and_subtype(ty)),
 
             // FIXME(unsafe_binders): Rename `handle_opaque_cast_and_subtype` to be more general.
             ProjectionElem::UnwrapUnsafeBinder(ty) => {
@@ -244,7 +243,6 @@ impl<V, T> ProjectionElem<V, T> {
             Self::Field(_, _)
             | Self::Index(_)
             | Self::OpaqueCast(_)
-            | Self::Subtype(_)
             | Self::ConstantIndex { .. }
             | Self::Subslice { .. }
             | Self::Downcast(_, _)
@@ -259,7 +257,6 @@ impl<V, T> ProjectionElem<V, T> {
             Self::Deref | Self::Index(_) => false,
             Self::Field(_, _)
             | Self::OpaqueCast(_)
-            | Self::Subtype(_)
             | Self::ConstantIndex { .. }
             | Self::Subslice { .. }
             | Self::Downcast(_, _)
@@ -286,7 +283,6 @@ impl<V, T> ProjectionElem<V, T> {
             | Self::Field(_, _) => true,
             Self::ConstantIndex { from_end: true, .. }
             | Self::Index(_)
-            | Self::Subtype(_)
             | Self::OpaqueCast(_)
             | Self::Subslice { .. } => false,
 
@@ -319,7 +315,6 @@ impl<V, T> ProjectionElem<V, T> {
                 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)?),
         })
@@ -706,7 +701,8 @@ impl<'tcx> Rvalue<'tcx> {
                 | CastKind::PtrToPtr
                 | CastKind::PointerCoercion(_, _)
                 | CastKind::PointerWithExposedProvenance
-                | CastKind::Transmute,
+                | CastKind::Transmute
+                | CastKind::Subtype,
                 _,
                 _,
             )
diff --git a/compiler/rustc_middle/src/mir/syntax.rs b/compiler/rustc_middle/src/mir/syntax.rs
index e6c8512564e..a823c365394 100644
--- a/compiler/rustc_middle/src/mir/syntax.rs
+++ b/compiler/rustc_middle/src/mir/syntax.rs
@@ -1275,18 +1275,6 @@ pub enum ProjectionElem<V, T> {
     /// A transmute from an unsafe binder to the type that it wraps. This is a projection
     /// of a place, so it doesn't necessarily constitute a move out of the binder.
     UnwrapUnsafeBinder(T),
-
-    /// A `Subtype(T)` projection is applied to any `StatementKind::Assign` where
-    /// type of lvalue doesn't match the type of rvalue, the primary goal is making subtyping
-    /// explicit during optimizations and codegen.
-    ///
-    /// This projection doesn't impact the runtime behavior of the program except for potentially changing
-    /// some type metadata of the interpreter or codegen backend.
-    ///
-    /// This goal is achieved with mir_transform pass `Subtyper`, which runs right after
-    /// borrowchecker, as we only care about subtyping that can affect trait selection and
-    /// `TypeId`.
-    Subtype(T),
 }
 
 /// Alias for projections as they appear in places, where the base is a place
@@ -1513,6 +1501,18 @@ pub enum CastKind {
     /// MIR is well-formed if the input and output types have different sizes,
     /// but running a transmute between differently-sized types is UB.
     Transmute,
+
+    /// A `Subtype` cast is applied to any `StatementKind::Assign` where
+    /// type of lvalue doesn't match the type of rvalue, the primary goal is making subtyping
+    /// explicit during optimizations and codegen.
+    ///
+    /// This cast doesn't impact the runtime behavior of the program except for potentially changing
+    /// some type metadata of the interpreter or codegen backend.
+    ///
+    /// This goal is achieved with mir_transform pass `Subtyper`, which runs right after
+    /// borrowchecker, as we only care about subtyping that can affect trait selection and
+    /// `TypeId`.
+    Subtype,
 }
 
 /// Represents how a [`CastKind::PointerCoercion`] was constructed.
diff --git a/compiler/rustc_middle/src/mir/visit.rs b/compiler/rustc_middle/src/mir/visit.rs
index 81df239dee4..f3923477800 100644
--- a/compiler/rustc_middle/src/mir/visit.rs
+++ b/compiler/rustc_middle/src/mir/visit.rs
@@ -1166,11 +1166,6 @@ macro_rules! visit_place_fns {
                     self.visit_ty(&mut new_ty, TyContext::Location(location));
                     if ty != new_ty { Some(PlaceElem::OpaqueCast(new_ty)) } else { None }
                 }
-                PlaceElem::Subtype(ty) => {
-                    let mut new_ty = ty;
-                    self.visit_ty(&mut new_ty, TyContext::Location(location));
-                    if ty != new_ty { Some(PlaceElem::Subtype(new_ty)) } else { None }
-                }
                 PlaceElem::UnwrapUnsafeBinder(ty) => {
                     let mut new_ty = ty;
                     self.visit_ty(&mut new_ty, TyContext::Location(location));
@@ -1244,7 +1239,6 @@ macro_rules! visit_place_fns {
         ) {
             match elem {
                 ProjectionElem::OpaqueCast(ty)
-                | ProjectionElem::Subtype(ty)
                 | ProjectionElem::Field(_, ty)
                 | ProjectionElem::UnwrapUnsafeBinder(ty) => {
                     self.visit_ty(ty, TyContext::Location(location));
diff --git a/compiler/rustc_mir_build/src/builder/expr/as_place.rs b/compiler/rustc_mir_build/src/builder/expr/as_place.rs
index 5a6bd2f413c..5e7a57d51a9 100644
--- a/compiler/rustc_mir_build/src/builder/expr/as_place.rs
+++ b/compiler/rustc_mir_build/src/builder/expr/as_place.rs
@@ -103,7 +103,7 @@ fn convert_to_hir_projections_and_truncate_for_capture(
             }
             ProjectionElem::UnwrapUnsafeBinder(_) => HirProjectionKind::UnwrapUnsafeBinder,
             // These do not affect anything, they just make sure we know the right type.
-            ProjectionElem::OpaqueCast(_) | ProjectionElem::Subtype(..) => continue,
+            ProjectionElem::OpaqueCast(_) => continue,
             ProjectionElem::Index(..)
             | ProjectionElem::ConstantIndex { .. }
             | ProjectionElem::Subslice { .. } => {
@@ -802,7 +802,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     ProjectionElem::Field(..)
                     | ProjectionElem::Downcast(..)
                     | ProjectionElem::OpaqueCast(..)
-                    | ProjectionElem::Subtype(..)
                     | ProjectionElem::ConstantIndex { .. }
                     | ProjectionElem::Subslice { .. }
                     | 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 72d4cd72c2b..434f106302f 100644
--- a/compiler/rustc_mir_dataflow/src/move_paths/builder.rs
+++ b/compiler/rustc_mir_dataflow/src/move_paths/builder.rs
@@ -227,11 +227,8 @@ impl<'a, 'tcx, F: Fn(Ty<'tcx>) -> bool> MoveDataBuilder<'a, 'tcx, F> {
                 ProjectionElem::UnwrapUnsafeBinder(_) => {}
                 // `OpaqueCast`:Only transmutes the type, so no moves there.
                 // `Downcast`  :Only changes information about a `Place` without moving.
-                // `Subtype`   :Only transmutes the type, so moves.
                 // So it's safe to skip these.
-                ProjectionElem::OpaqueCast(_)
-                | ProjectionElem::Subtype(_)
-                | ProjectionElem::Downcast(_, _) => (),
+                ProjectionElem::OpaqueCast(_) | ProjectionElem::Downcast(_, _) => (),
             }
             let elem_ty = PlaceTy::from_ty(place_ty).projection_ty(tcx, elem).ty;
             if !(self.filter)(elem_ty) {
diff --git a/compiler/rustc_mir_transform/src/add_subtyping_projections.rs b/compiler/rustc_mir_transform/src/add_subtyping_projections.rs
index be4f84d64d0..a6a60fddf90 100644
--- a/compiler/rustc_mir_transform/src/add_subtyping_projections.rs
+++ b/compiler/rustc_mir_transform/src/add_subtyping_projections.rs
@@ -40,8 +40,7 @@ impl<'a, 'tcx> MutVisitor<'tcx> for SubTypeChecker<'a, 'tcx> {
                 .new_temp(rval_ty, self.local_decls[place.as_ref().local].source_info.span);
             let new_place = Place::from(temp);
             self.patcher.add_assign(location, new_place, rvalue.clone());
-            let subtyped = new_place.project_deeper(&[ProjectionElem::Subtype(place_ty)], self.tcx);
-            *rvalue = Rvalue::Use(Operand::Move(subtyped));
+            *rvalue = Rvalue::Cast(CastKind::Subtype, Operand::Move(new_place), place_ty);
         }
     }
 }
diff --git a/compiler/rustc_mir_transform/src/dataflow_const_prop.rs b/compiler/rustc_mir_transform/src/dataflow_const_prop.rs
index 491e910ff6f..e970f7ff81a 100644
--- a/compiler/rustc_mir_transform/src/dataflow_const_prop.rs
+++ b/compiler/rustc_mir_transform/src/dataflow_const_prop.rs
@@ -440,7 +440,7 @@ impl<'a, 'tcx> ConstAnalysis<'a, 'tcx> {
                     FlatSet::Top => FlatSet::Top,
                 }
             }
-            Rvalue::Cast(CastKind::Transmute, operand, _) => {
+            Rvalue::Cast(CastKind::Transmute | CastKind::Subtype, operand, _) => {
                 match self.eval_operand(operand, state) {
                     FlatSet::Elem(op) => self.wrap_immediate(*op),
                     FlatSet::Bottom => FlatSet::Bottom,
diff --git a/compiler/rustc_mir_transform/src/gvn.rs b/compiler/rustc_mir_transform/src/gvn.rs
index 29f6879aacd..99691d9e045 100644
--- a/compiler/rustc_mir_transform/src/gvn.rs
+++ b/compiler/rustc_mir_transform/src/gvn.rs
@@ -656,7 +656,7 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
                     let res = self.ecx.float_to_float_or_int(&value, ty).discard_err()?;
                     res.into()
                 }
-                CastKind::Transmute => {
+                CastKind::Transmute | CastKind::Subtype => {
                     let value = self.evaluated[value].as_ref()?;
                     // `offset` for immediates generally only supports projections that match the
                     // type of the immediate. However, as a HACK, we exploit that it can also do
@@ -788,7 +788,6 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
                 ProjectionElem::Subslice { from, to, from_end }
             }
             ProjectionElem::OpaqueCast(_) => ProjectionElem::OpaqueCast(()),
-            ProjectionElem::Subtype(_) => ProjectionElem::Subtype(()),
             ProjectionElem::UnwrapUnsafeBinder(_) => ProjectionElem::UnwrapUnsafeBinder(()),
         };
 
diff --git a/compiler/rustc_mir_transform/src/known_panics_lint.rs b/compiler/rustc_mir_transform/src/known_panics_lint.rs
index 5fffba55f17..93abc0f8860 100644
--- a/compiler/rustc_mir_transform/src/known_panics_lint.rs
+++ b/compiler/rustc_mir_transform/src/known_panics_lint.rs
@@ -637,7 +637,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
                     let res = self.ecx.float_to_float_or_int(&value, to).discard_err()?;
                     res.into()
                 }
-                CastKind::Transmute => {
+                CastKind::Transmute | CastKind::Subtype => {
                     let value = self.eval_operand(value)?;
                     let to = self.ecx.layout_of(to).ok()?;
                     // `offset` for immediates only supports scalar/scalar-pair ABIs,
diff --git a/compiler/rustc_mir_transform/src/promote_consts.rs b/compiler/rustc_mir_transform/src/promote_consts.rs
index a0b0c8c990f..48ddf5a1bca 100644
--- a/compiler/rustc_mir_transform/src/promote_consts.rs
+++ b/compiler/rustc_mir_transform/src/promote_consts.rs
@@ -292,7 +292,6 @@ impl<'tcx> Validator<'_, 'tcx> {
         match elem {
             // Recurse directly.
             ProjectionElem::ConstantIndex { .. }
-            | ProjectionElem::Subtype(_)
             | ProjectionElem::Subslice { .. }
             | ProjectionElem::UnwrapUnsafeBinder(_) => {}
 
diff --git a/compiler/rustc_mir_transform/src/validate.rs b/compiler/rustc_mir_transform/src/validate.rs
index c8a9a88dc3f..cbabb982df8 100644
--- a/compiler/rustc_mir_transform/src/validate.rs
+++ b/compiler/rustc_mir_transform/src/validate.rs
@@ -814,22 +814,6 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                     }
                 }
             }
-            ProjectionElem::Subtype(ty) => {
-                if !util::sub_types(
-                    self.tcx,
-                    self.typing_env,
-                    ty,
-                    place_ref.ty(&self.body.local_decls, self.tcx).ty,
-                ) {
-                    self.fail(
-                        location,
-                        format!(
-                            "Failed subtyping {ty} and {}",
-                            place_ref.ty(&self.body.local_decls, self.tcx).ty
-                        ),
-                    )
-                }
-            }
             ProjectionElem::UnwrapUnsafeBinder(unwrapped_ty) => {
                 let binder_ty = place_ref.ty(&self.body.local_decls, self.tcx);
                 let ty::UnsafeBinder(binder_ty) = *binder_ty.ty.kind() else {
@@ -1331,6 +1315,14 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                             );
                         }
                     }
+                    CastKind::Subtype => {
+                        if !util::sub_types(self.tcx, self.typing_env, op_ty, *target_type) {
+                            self.fail(
+                                location,
+                                format!("Failed subtyping {op_ty} and {target_type}"),
+                            )
+                        }
+                    }
                 }
             }
             Rvalue::NullaryOp(NullOp::OffsetOf(indices), container) => {
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 a2e6ef6f0fe..d58c264841c 100644
--- a/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/assembly/mod.rs
@@ -473,7 +473,10 @@ where
         // fails to reach a fixpoint but ends up getting an error after
         // running for some additional step.
         //
-        // cc trait-system-refactor-initiative#105
+        // FIXME(@lcnr): While I believe an error here to be possible, we
+        // currently don't have any test which actually triggers it. @lqd
+        // created a minimization for an ICE in typenum, but that one no
+        // longer fails here. cc trait-system-refactor-initiative#105.
         let source = CandidateSource::BuiltinImpl(BuiltinImplSource::Misc);
         let certainty = Certainty::Maybe { cause, opaque_types_jank: OpaqueTypesJank::AllGood };
         self.probe_trait_candidate(source)
diff --git a/compiler/rustc_parse/src/parser/diagnostics.rs b/compiler/rustc_parse/src/parser/diagnostics.rs
index a28af7833c3..a9fbd0fa33d 100644
--- a/compiler/rustc_parse/src/parser/diagnostics.rs
+++ b/compiler/rustc_parse/src/parser/diagnostics.rs
@@ -2748,28 +2748,7 @@ impl<'a> Parser<'a> {
         if token::Colon != self.token.kind {
             return first_pat;
         }
-        if !matches!(first_pat.kind, PatKind::Ident(_, _, None) | PatKind::Path(..))
-            || !self.look_ahead(1, |token| token.is_non_reserved_ident())
-        {
-            let mut snapshot_type = self.create_snapshot_for_diagnostic();
-            snapshot_type.bump(); // `:`
-            match snapshot_type.parse_ty() {
-                Err(inner_err) => {
-                    inner_err.cancel();
-                }
-                Ok(ty) => {
-                    let Err(mut err) = self.expected_one_of_not_found(&[], &[]) else {
-                        return first_pat;
-                    };
-                    err.span_label(ty.span, "specifying the type of a pattern isn't supported");
-                    self.restore_snapshot(snapshot_type);
-                    let span = first_pat.span.to(ty.span);
-                    first_pat = self.mk_pat(span, PatKind::Wild);
-                    err.emit();
-                }
-            }
-            return first_pat;
-        }
+
         // The pattern looks like it might be a path with a `::` -> `:` typo:
         // `match foo { bar:baz => {} }`
         let colon_span = self.token.span;
@@ -2857,7 +2836,13 @@ impl<'a> Parser<'a> {
                                 Applicability::MaybeIncorrect,
                             );
                         } else {
-                            first_pat = self.mk_pat(new_span, PatKind::Wild);
+                            first_pat = self.mk_pat(
+                                new_span,
+                                PatKind::Err(
+                                    self.dcx()
+                                        .span_delayed_bug(colon_span, "recovered bad path pattern"),
+                                ),
+                            );
                         }
                         self.restore_snapshot(snapshot_pat);
                     }
@@ -2870,7 +2855,14 @@ impl<'a> Parser<'a> {
                         err.span_label(ty.span, "specifying the type of a pattern isn't supported");
                         self.restore_snapshot(snapshot_type);
                         let new_span = first_pat.span.to(ty.span);
-                        first_pat = self.mk_pat(new_span, PatKind::Wild);
+                        first_pat =
+                            self.mk_pat(
+                                new_span,
+                                PatKind::Err(self.dcx().span_delayed_bug(
+                                    colon_span,
+                                    "recovered bad pattern with type",
+                                )),
+                            );
                     }
                 }
                 err.emit();
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index 81a5d48d94e..8046abcd70b 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -3612,7 +3612,7 @@ impl<'a> Parser<'a> {
         self.token.is_keyword(kw::Async) && self.is_gen_block(kw::Gen, 1)
     }
 
-    fn is_certainly_not_a_block(&self) -> bool {
+    fn is_likely_struct_lit(&self) -> bool {
         // `{ ident, ` and `{ ident: ` cannot start a block.
         self.look_ahead(1, |t| t.is_ident())
             && self.look_ahead(2, |t| t == &token::Comma || t == &token::Colon)
@@ -3624,24 +3624,50 @@ impl<'a> Parser<'a> {
         path: &ast::Path,
     ) -> Option<PResult<'a, Box<Expr>>> {
         let struct_allowed = !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL);
-        if struct_allowed || self.is_certainly_not_a_block() {
-            if let Err(err) = self.expect(exp!(OpenBrace)) {
-                return Some(Err(err));
+        match (struct_allowed, self.is_likely_struct_lit()) {
+            // A struct literal isn't expected and one is pretty much assured not to be present. The
+            // only situation that isn't detected is when a struct with a single field was attempted
+            // in a place where a struct literal wasn't expected, but regular parser errors apply.
+            // Happy path.
+            (false, false) => None,
+            (true, _) => {
+                // A struct is accepted here, try to parse it and rely on `parse_expr_struct` for
+                // any kind of recovery. Happy path.
+                if let Err(err) = self.expect(exp!(OpenBrace)) {
+                    return Some(Err(err));
+                }
+                Some(self.parse_expr_struct(qself.clone(), path.clone(), true))
             }
-            let expr = self.parse_expr_struct(qself.clone(), path.clone(), true);
-            if let (Ok(expr), false) = (&expr, struct_allowed) {
-                // This is a struct literal, but we don't can't accept them here.
-                self.dcx().emit_err(errors::StructLiteralNotAllowedHere {
-                    span: expr.span,
-                    sub: errors::StructLiteralNotAllowedHereSugg {
-                        left: path.span.shrink_to_lo(),
-                        right: expr.span.shrink_to_hi(),
-                    },
-                });
+            (false, true) => {
+                // We have something like `match foo { bar,` or `match foo { bar:`, which means the
+                // user might have meant to write a struct literal as part of the `match`
+                // discriminant. This is done purely for error recovery.
+                let snapshot = self.create_snapshot_for_diagnostic();
+                if let Err(err) = self.expect(exp!(OpenBrace)) {
+                    return Some(Err(err));
+                }
+                match self.parse_expr_struct(qself.clone(), path.clone(), false) {
+                    Ok(expr) => {
+                        // This is a struct literal, but we don't accept them here.
+                        self.dcx().emit_err(errors::StructLiteralNotAllowedHere {
+                            span: expr.span,
+                            sub: errors::StructLiteralNotAllowedHereSugg {
+                                left: path.span.shrink_to_lo(),
+                                right: expr.span.shrink_to_hi(),
+                            },
+                        });
+                        Some(Ok(expr))
+                    }
+                    Err(err) => {
+                        // We couldn't parse a valid struct, rollback and let the parser emit an
+                        // error elsewhere.
+                        err.cancel();
+                        self.restore_snapshot(snapshot);
+                        None
+                    }
+                }
             }
-            return Some(expr);
         }
-        None
     }
 
     pub(super) fn parse_struct_fields(
diff --git a/compiler/rustc_public/src/mir/body.rs b/compiler/rustc_public/src/mir/body.rs
index 276adacd99e..7bd06fee721 100644
--- a/compiler/rustc_public/src/mir/body.rs
+++ b/compiler/rustc_public/src/mir/body.rs
@@ -836,14 +836,6 @@ pub enum ProjectionElem {
     /// Like an explicit cast from an opaque type to a concrete type, but without
     /// requiring an intermediate variable.
     OpaqueCast(Ty),
-
-    /// A `Subtype(T)` projection is applied to any `StatementKind::Assign` where
-    /// type of lvalue doesn't match the type of rvalue, the primary goal is making subtyping
-    /// explicit during optimizations and codegen.
-    ///
-    /// This projection doesn't impact the runtime behavior of the program except for potentially changing
-    /// some type metadata of the interpreter or codegen backend.
-    Subtype(Ty),
 }
 
 #[derive(Clone, Debug, Eq, PartialEq, Serialize)]
@@ -1028,6 +1020,7 @@ pub enum CastKind {
     PtrToPtr,
     FnPtrToPtr,
     Transmute,
+    Subtype,
 }
 
 #[derive(Clone, Debug, Eq, PartialEq, Hash, Serialize)]
@@ -1089,7 +1082,7 @@ impl ProjectionElem {
                 Self::subslice_ty(ty, *from, *to, *from_end)
             }
             ProjectionElem::Downcast(_) => Ok(ty),
-            ProjectionElem::OpaqueCast(ty) | ProjectionElem::Subtype(ty) => Ok(*ty),
+            ProjectionElem::OpaqueCast(ty) => Ok(*ty),
         }
     }
 
diff --git a/compiler/rustc_public/src/mir/visit.rs b/compiler/rustc_public/src/mir/visit.rs
index 04c4d4d2a82..7563c9ca008 100644
--- a/compiler/rustc_public/src/mir/visit.rs
+++ b/compiler/rustc_public/src/mir/visit.rs
@@ -471,7 +471,6 @@ macro_rules! visit_place_fns {
                 ProjectionElem::Subslice { from: _, to: _, from_end: _ } => {}
                 ProjectionElem::Downcast(_idx) => {}
                 ProjectionElem::OpaqueCast(ty) => self.visit_ty(ty, location),
-                ProjectionElem::Subtype(ty) => self.visit_ty(ty, location),
             }
         }
     };
@@ -512,7 +511,6 @@ macro_rules! visit_place_fns {
                 ProjectionElem::Subslice { from: _, to: _, from_end: _ } => {}
                 ProjectionElem::Downcast(_idx) => {}
                 ProjectionElem::OpaqueCast(ty) => self.visit_ty(ty, location),
-                ProjectionElem::Subtype(ty) => self.visit_ty(ty, location),
             }
         }
     };
diff --git a/compiler/rustc_public/src/unstable/convert/internal.rs b/compiler/rustc_public/src/unstable/convert/internal.rs
index dc9abd88614..064fb6c6803 100644
--- a/compiler/rustc_public/src/unstable/convert/internal.rs
+++ b/compiler/rustc_public/src/unstable/convert/internal.rs
@@ -703,9 +703,6 @@ impl RustcInternal for ProjectionElem {
             ProjectionElem::OpaqueCast(ty) => {
                 rustc_middle::mir::PlaceElem::OpaqueCast(ty.internal(tables, tcx))
             }
-            ProjectionElem::Subtype(ty) => {
-                rustc_middle::mir::PlaceElem::Subtype(ty.internal(tables, tcx))
-            }
         }
     }
 }
diff --git a/compiler/rustc_public/src/unstable/convert/stable/mir.rs b/compiler/rustc_public/src/unstable/convert/stable/mir.rs
index b10af6526ea..62ab91d17ba 100644
--- a/compiler/rustc_public/src/unstable/convert/stable/mir.rs
+++ b/compiler/rustc_public/src/unstable/convert/stable/mir.rs
@@ -356,6 +356,7 @@ impl<'tcx> Stable<'tcx> for mir::CastKind {
             PtrToPtr => crate::mir::CastKind::PtrToPtr,
             FnPtrToPtr => crate::mir::CastKind::FnPtrToPtr,
             Transmute => crate::mir::CastKind::Transmute,
+            Subtype => crate::mir::CastKind::Subtype,
         }
     }
 }
@@ -453,7 +454,6 @@ impl<'tcx> Stable<'tcx> for mir::PlaceElem<'tcx> {
             // found at https://github.com/rust-lang/rust/pull/117517#issuecomment-1811683486
             Downcast(_, idx) => crate::mir::ProjectionElem::Downcast(idx.stable(tables, cx)),
             OpaqueCast(ty) => crate::mir::ProjectionElem::OpaqueCast(ty.stable(tables, cx)),
-            Subtype(ty) => crate::mir::ProjectionElem::Subtype(ty.stable(tables, cx)),
             UnwrapUnsafeBinder(..) => todo!("FIXME(unsafe_binders):"),
         }
     }
diff --git a/compiler/rustc_target/src/spec/targets/wasm32_wali_linux_musl.rs b/compiler/rustc_target/src/spec/targets/wasm32_wali_linux_musl.rs
index a0eb4a254fc..06e5cfaed92 100644
--- a/compiler/rustc_target/src/spec/targets/wasm32_wali_linux_musl.rs
+++ b/compiler/rustc_target/src/spec/targets/wasm32_wali_linux_musl.rs
@@ -6,11 +6,18 @@ use crate::spec::{Cc, LinkerFlavor, Target, TargetMetadata, base};
 pub(crate) fn target() -> Target {
     let mut options = base::linux_wasm::opts();
 
-    options
-        .add_pre_link_args(LinkerFlavor::WasmLld(Cc::No), &["--export-memory", "--shared-memory"]);
+    options.add_pre_link_args(
+        LinkerFlavor::WasmLld(Cc::No),
+        &["--export-memory", "--shared-memory", "--max-memory=1073741824"],
+    );
     options.add_pre_link_args(
         LinkerFlavor::WasmLld(Cc::Yes),
-        &["--target=wasm32-wasi-threads", "-Wl,--export-memory,", "-Wl,--shared-memory"],
+        &[
+            "--target=wasm32-wasi-threads",
+            "-Wl,--export-memory,",
+            "-Wl,--shared-memory",
+            "-Wl,--max-memory=1073741824",
+        ],
     );
 
     Target {
diff --git a/compiler/rustc_target/src/spec/targets/wasm32_wasip1_threads.rs b/compiler/rustc_target/src/spec/targets/wasm32_wasip1_threads.rs
index 44d906a507d..c735c72cb1c 100644
--- a/compiler/rustc_target/src/spec/targets/wasm32_wasip1_threads.rs
+++ b/compiler/rustc_target/src/spec/targets/wasm32_wasip1_threads.rs
@@ -19,7 +19,7 @@ pub(crate) fn target() -> Target {
 
     options.add_pre_link_args(
         LinkerFlavor::WasmLld(Cc::No),
-        &["--import-memory", "--export-memory", "--shared-memory"],
+        &["--import-memory", "--export-memory", "--shared-memory", "--max-memory=1073741824"],
     );
     options.add_pre_link_args(
         LinkerFlavor::WasmLld(Cc::Yes),
@@ -28,6 +28,7 @@ pub(crate) fn target() -> Target {
             "-Wl,--import-memory",
             "-Wl,--export-memory,",
             "-Wl,--shared-memory",
+            "-Wl,--max-memory=1073741824",
         ],
     );
 
diff --git a/compiler/rustc_trait_selection/src/regions.rs b/compiler/rustc_trait_selection/src/regions.rs
index 2b33b8ac9f8..debc4fda15a 100644
--- a/compiler/rustc_trait_selection/src/regions.rs
+++ b/compiler/rustc_trait_selection/src/regions.rs
@@ -77,6 +77,8 @@ impl<'tcx> InferCtxt<'tcx> {
     ///
     /// Prefer this method over `resolve_regions_with_normalize`, unless you are
     /// doing something specific for normalization.
+    ///
+    /// This function assumes that all infer variables are already constrained.
     fn resolve_regions(
         &self,
         body_id: LocalDefId,
diff --git a/compiler/rustc_type_ir/src/flags.rs b/compiler/rustc_type_ir/src/flags.rs
index 24704c5bb53..ea3903d401e 100644
--- a/compiler/rustc_type_ir/src/flags.rs
+++ b/compiler/rustc_type_ir/src/flags.rs
@@ -347,6 +347,7 @@ impl<I: Interner> FlagComputation<I> {
 
     fn add_ty_pat(&mut self, pat: <I as Interner>::Pat) {
         self.add_flags(pat.flags());
+        self.add_exclusive_binder(pat.outer_exclusive_binder());
     }
 
     fn add_predicate(&mut self, binder: ty::Binder<I, ty::PredicateKind<I>>) {
diff --git a/library/alloc/src/boxed.rs b/library/alloc/src/boxed.rs
index 5a63d90b95f..49ff768bed1 100644
--- a/library/alloc/src/boxed.rs
+++ b/library/alloc/src/boxed.rs
@@ -619,6 +619,37 @@ impl<T, A: Allocator> Box<T, A> {
     pub fn into_inner(boxed: Self) -> T {
         *boxed
     }
+
+    /// Consumes the `Box` without consuming its allocation, returning the wrapped value and a `Box`
+    /// to the uninitialized memory where the wrapped value used to live.
+    ///
+    /// This can be used together with [`write`](Box::write) to reuse the allocation for multiple
+    /// boxed values.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// #![feature(box_take)]
+    ///
+    /// let c = Box::new(5);
+    ///
+    /// // take the value out of the box
+    /// let (value, uninit) = Box::take(c);
+    /// assert_eq!(value, 5);
+    ///
+    /// // reuse the box for a second value
+    /// let c = Box::write(uninit, 6);
+    /// assert_eq!(*c, 6);
+    /// ```
+    #[unstable(feature = "box_take", issue = "147212")]
+    pub fn take(boxed: Self) -> (T, Box<mem::MaybeUninit<T>, A>) {
+        unsafe {
+            let (raw, alloc) = Box::into_raw_with_allocator(boxed);
+            let value = raw.read();
+            let uninit = Box::from_raw_in(raw.cast::<mem::MaybeUninit<T>>(), alloc);
+            (value, uninit)
+        }
+    }
 }
 
 impl<T> Box<[T]> {
diff --git a/library/core/src/slice/iter.rs b/library/core/src/slice/iter.rs
index ae910e05252..7053ae86e73 100644
--- a/library/core/src/slice/iter.rs
+++ b/library/core/src/slice/iter.rs
@@ -2203,16 +2203,13 @@ unsafe impl<T> Sync for ChunksExactMut<'_, T> where T: Sync {}
 #[unstable(feature = "array_windows", issue = "75027")]
 #[must_use = "iterators are lazy and do nothing unless consumed"]
 pub struct ArrayWindows<'a, T: 'a, const N: usize> {
-    slice_head: *const T,
-    num: usize,
-    marker: PhantomData<&'a [T; N]>,
+    v: &'a [T],
 }
 
 impl<'a, T: 'a, const N: usize> ArrayWindows<'a, T, N> {
     #[inline]
     pub(super) const fn new(slice: &'a [T]) -> Self {
-        let num_windows = slice.len().saturating_sub(N - 1);
-        Self { slice_head: slice.as_ptr(), num: num_windows, marker: PhantomData }
+        Self { v: slice }
     }
 }
 
@@ -2222,49 +2219,34 @@ impl<'a, T, const N: usize> Iterator for ArrayWindows<'a, T, N> {
 
     #[inline]
     fn next(&mut self) -> Option<Self::Item> {
-        if self.num == 0 {
-            return None;
+        let ret = self.v.first_chunk();
+        if ret.is_some() {
+            self.v = &self.v[1..];
         }
-        // SAFETY:
-        // This is safe because it's indexing into a slice guaranteed to be length > N.
-        let ret = unsafe { &*self.slice_head.cast::<[T; N]>() };
-        // SAFETY: Guaranteed that there are at least 1 item remaining otherwise
-        // earlier branch would've been hit
-        self.slice_head = unsafe { self.slice_head.add(1) };
-
-        self.num -= 1;
-        Some(ret)
+        ret
     }
 
     #[inline]
     fn size_hint(&self) -> (usize, Option<usize>) {
-        (self.num, Some(self.num))
+        let size = self.v.len().saturating_sub(N - 1);
+        (size, Some(size))
     }
 
     #[inline]
     fn count(self) -> usize {
-        self.num
+        self.len()
     }
 
     #[inline]
     fn nth(&mut self, n: usize) -> Option<Self::Item> {
-        if self.num <= n {
-            self.num = 0;
-            return None;
-        }
-        // SAFETY:
-        // This is safe because it's indexing into a slice guaranteed to be length > N.
-        let ret = unsafe { &*self.slice_head.add(n).cast::<[T; N]>() };
-        // SAFETY: Guaranteed that there are at least n items remaining
-        self.slice_head = unsafe { self.slice_head.add(n + 1) };
-
-        self.num -= n + 1;
-        Some(ret)
+        let idx = n.min(self.v.len());
+        self.v = &self.v[idx..];
+        self.next()
     }
 
     #[inline]
-    fn last(mut self) -> Option<Self::Item> {
-        self.nth(self.num.checked_sub(1)?)
+    fn last(self) -> Option<Self::Item> {
+        self.v.last_chunk()
     }
 }
 
@@ -2272,32 +2254,25 @@ impl<'a, T, const N: usize> Iterator for ArrayWindows<'a, T, N> {
 impl<'a, T, const N: usize> DoubleEndedIterator for ArrayWindows<'a, T, N> {
     #[inline]
     fn next_back(&mut self) -> Option<&'a [T; N]> {
-        if self.num == 0 {
-            return None;
+        let ret = self.v.last_chunk();
+        if ret.is_some() {
+            self.v = &self.v[..self.v.len() - 1];
         }
-        // SAFETY: Guaranteed that there are n items remaining, n-1 for 0-indexing.
-        let ret = unsafe { &*self.slice_head.add(self.num - 1).cast::<[T; N]>() };
-        self.num -= 1;
-        Some(ret)
+        ret
     }
 
     #[inline]
     fn nth_back(&mut self, n: usize) -> Option<&'a [T; N]> {
-        if self.num <= n {
-            self.num = 0;
-            return None;
-        }
-        // SAFETY: Guaranteed that there are n items remaining, n-1 for 0-indexing.
-        let ret = unsafe { &*self.slice_head.add(self.num - (n + 1)).cast::<[T; N]>() };
-        self.num -= n + 1;
-        Some(ret)
+        let idx = self.v.len().saturating_sub(n);
+        self.v = &self.v[..idx];
+        self.next_back()
     }
 }
 
 #[unstable(feature = "array_windows", issue = "75027")]
 impl<T, const N: usize> ExactSizeIterator for ArrayWindows<'_, T, N> {
     fn is_empty(&self) -> bool {
-        self.num == 0
+        self.v.len() < N
     }
 }
 
diff --git a/library/coretests/tests/iter/sources.rs b/library/coretests/tests/iter/sources.rs
index 506febaa056..5a391cb6775 100644
--- a/library/coretests/tests/iter/sources.rs
+++ b/library/coretests/tests/iter/sources.rs
@@ -31,6 +31,17 @@ fn test_repeat_take_collect() {
 }
 
 #[test]
+#[should_panic = "iterator is infinite"]
+fn test_repeat_count() {
+    repeat(42).count();
+}
+
+#[test]
+fn test_repeat_last() {
+    assert_eq!(repeat(42).last(), Some(42));
+}
+
+#[test]
 fn test_repeat_with() {
     #[derive(PartialEq, Debug)]
     struct NotClone(usize);
diff --git a/library/std/src/sys/net/hostname/mod.rs b/library/std/src/sys/net/hostname/mod.rs
index a4b5b76059d..8ffe4894d71 100644
--- a/library/std/src/sys/net/hostname/mod.rs
+++ b/library/std/src/sys/net/hostname/mod.rs
@@ -1,5 +1,5 @@
 cfg_select! {
-    target_family = "unix" => {
+    all(target_family = "unix", not(target_os = "espidf")) => {
         mod unix;
         pub use unix::hostname;
     }
diff --git a/library/std/src/sys/thread_local/mod.rs b/library/std/src/sys/thread_local/mod.rs
index d5c795093cf..f7f051b1add 100644
--- a/library/std/src/sys/thread_local/mod.rs
+++ b/library/std/src/sys/thread_local/mod.rs
@@ -42,7 +42,7 @@ cfg_select! {
     }
     _ => {
         mod os;
-        pub use os::{Storage, thread_local_inner};
+        pub use os::{Storage, thread_local_inner, value_align};
         pub(crate) use os::{LocalPointer, local_pointer};
     }
 }
diff --git a/library/std/src/sys/thread_local/native/eager.rs b/library/std/src/sys/thread_local/native/eager.rs
index fd48c4f7202..23abad645c1 100644
--- a/library/std/src/sys/thread_local/native/eager.rs
+++ b/library/std/src/sys/thread_local/native/eager.rs
@@ -10,9 +10,11 @@ enum State {
 }
 
 #[allow(missing_debug_implementations)]
+#[repr(C)]
 pub struct Storage<T> {
-    state: Cell<State>,
+    // This field must be first, for correctness of `#[rustc_align_static]`
     val: UnsafeCell<T>,
+    state: Cell<State>,
 }
 
 impl<T> Storage<T> {
diff --git a/library/std/src/sys/thread_local/native/lazy.rs b/library/std/src/sys/thread_local/native/lazy.rs
index b556dd9aa25..02939a74fc0 100644
--- a/library/std/src/sys/thread_local/native/lazy.rs
+++ b/library/std/src/sys/thread_local/native/lazy.rs
@@ -27,9 +27,11 @@ enum State<D> {
 }
 
 #[allow(missing_debug_implementations)]
+#[repr(C)]
 pub struct Storage<T, D> {
-    state: Cell<State<D>>,
+    // This field must be first, for correctness of `#[rustc_align_static]`
     value: UnsafeCell<MaybeUninit<T>>,
+    state: Cell<State<D>>,
 }
 
 impl<T, D> Storage<T, D>
diff --git a/library/std/src/sys/thread_local/native/mod.rs b/library/std/src/sys/thread_local/native/mod.rs
index a5dffe3c458..5dc14240804 100644
--- a/library/std/src/sys/thread_local/native/mod.rs
+++ b/library/std/src/sys/thread_local/native/mod.rs
@@ -54,7 +54,7 @@ pub macro thread_local_inner {
     // test in `tests/thread.rs` if these types are renamed.
 
     // Used to generate the `LocalKey` value for const-initialized thread locals.
-    (@key $t:ty, const $init:expr) => {{
+    (@key $t:ty, $(#[$align_attr:meta])*, const $init:expr) => {{
         const __INIT: $t = $init;
 
         unsafe {
@@ -62,6 +62,7 @@ pub macro thread_local_inner {
                 if $crate::mem::needs_drop::<$t>() {
                     |_| {
                         #[thread_local]
+                        $(#[$align_attr])*
                         static VAL: $crate::thread::local_impl::EagerStorage<$t>
                             = $crate::thread::local_impl::EagerStorage::new(__INIT);
                         VAL.get()
@@ -69,6 +70,7 @@ pub macro thread_local_inner {
                 } else {
                     |_| {
                         #[thread_local]
+                        $(#[$align_attr])*
                         static VAL: $t = __INIT;
                         &VAL
                     }
@@ -78,7 +80,7 @@ pub macro thread_local_inner {
     }},
 
     // used to generate the `LocalKey` value for `thread_local!`
-    (@key $t:ty, $init:expr) => {{
+    (@key $t:ty, $(#[$align_attr:meta])*, $init:expr) => {{
         #[inline]
         fn __init() -> $t {
             $init
@@ -89,6 +91,7 @@ pub macro thread_local_inner {
                 if $crate::mem::needs_drop::<$t>() {
                     |init| {
                         #[thread_local]
+                        $(#[$align_attr])*
                         static VAL: $crate::thread::local_impl::LazyStorage<$t, ()>
                             = $crate::thread::local_impl::LazyStorage::new();
                         VAL.get_or_init(init, __init)
@@ -96,6 +99,7 @@ pub macro thread_local_inner {
                 } else {
                     |init| {
                         #[thread_local]
+                        $(#[$align_attr])*
                         static VAL: $crate::thread::local_impl::LazyStorage<$t, !>
                             = $crate::thread::local_impl::LazyStorage::new();
                         VAL.get_or_init(init, __init)
@@ -104,10 +108,6 @@ pub macro thread_local_inner {
             })
         }
     }},
-    ($(#[$attr:meta])* $vis:vis $name:ident, $t:ty, $($init:tt)*) => {
-        $(#[$attr])* $vis const $name: $crate::thread::LocalKey<$t> =
-            $crate::thread::local_impl::thread_local_inner!(@key $t, $($init)*);
-    },
 }
 
 #[rustc_macro_transparency = "semitransparent"]
diff --git a/library/std/src/sys/thread_local/no_threads.rs b/library/std/src/sys/thread_local/no_threads.rs
index 4da01a84acf..409dfb19518 100644
--- a/library/std/src/sys/thread_local/no_threads.rs
+++ b/library/std/src/sys/thread_local/no_threads.rs
@@ -2,6 +2,7 @@
 //! thread locals and we can instead just use plain statics!
 
 use crate::cell::{Cell, UnsafeCell};
+use crate::mem::MaybeUninit;
 use crate::ptr;
 
 #[doc(hidden)]
@@ -11,12 +12,13 @@ use crate::ptr;
 #[rustc_macro_transparency = "semitransparent"]
 pub macro thread_local_inner {
     // used to generate the `LocalKey` value for const-initialized thread locals
-    (@key $t:ty, const $init:expr) => {{
+    (@key $t:ty, $(#[$align_attr:meta])*, const $init:expr) => {{
         const __INIT: $t = $init;
 
         // NOTE: Please update the shadowing test in `tests/thread.rs` if these types are renamed.
         unsafe {
             $crate::thread::LocalKey::new(|_| {
+                $(#[$align_attr])*
                 static VAL: $crate::thread::local_impl::EagerStorage<$t> =
                     $crate::thread::local_impl::EagerStorage { value: __INIT };
                 &VAL.value
@@ -25,27 +27,22 @@ pub macro thread_local_inner {
     }},
 
     // used to generate the `LocalKey` value for `thread_local!`
-    (@key $t:ty, $init:expr) => {{
+    (@key $t:ty, $(#[$align_attr:meta])*, $init:expr) => {{
         #[inline]
         fn __init() -> $t { $init }
 
         unsafe {
-            use $crate::thread::LocalKey;
-            use $crate::thread::local_impl::LazyStorage;
-
-            LocalKey::new(|init| {
-                static VAL: LazyStorage<$t> = LazyStorage::new();
+            $crate::thread::LocalKey::new(|init| {
+                $(#[$align_attr])*
+                static VAL: $crate::thread::local_impl::LazyStorage<$t> = $crate::thread::local_impl::LazyStorage::new();
                 VAL.get(init, __init)
             })
         }
     }},
-    ($(#[$attr:meta])* $vis:vis $name:ident, $t:ty, $($init:tt)*) => {
-        $(#[$attr])* $vis const $name: $crate::thread::LocalKey<$t> =
-            $crate::thread::local_impl::thread_local_inner!(@key $t, $($init)*);
-    },
 }
 
 #[allow(missing_debug_implementations)]
+#[repr(transparent)] // Required for correctness of `#[rustc_align_static]`
 pub struct EagerStorage<T> {
     pub value: T,
 }
@@ -53,14 +50,27 @@ pub struct EagerStorage<T> {
 // SAFETY: the target doesn't have threads.
 unsafe impl<T> Sync for EagerStorage<T> {}
 
+#[derive(Clone, Copy, PartialEq, Eq)]
+enum State {
+    Initial,
+    Alive,
+    Destroying,
+}
+
 #[allow(missing_debug_implementations)]
+#[repr(C)]
 pub struct LazyStorage<T> {
-    value: UnsafeCell<Option<T>>,
+    // This field must be first, for correctness of `#[rustc_align_static]`
+    value: UnsafeCell<MaybeUninit<T>>,
+    state: Cell<State>,
 }
 
 impl<T> LazyStorage<T> {
     pub const fn new() -> LazyStorage<T> {
-        LazyStorage { value: UnsafeCell::new(None) }
+        LazyStorage {
+            value: UnsafeCell::new(MaybeUninit::uninit()),
+            state: Cell::new(State::Initial),
+        }
     }
 
     /// Gets a pointer to the TLS value, potentially initializing it with the
@@ -70,24 +80,39 @@ impl<T> LazyStorage<T> {
     /// has occurred.
     #[inline]
     pub fn get(&'static self, i: Option<&mut Option<T>>, f: impl FnOnce() -> T) -> *const T {
-        let value = unsafe { &*self.value.get() };
-        match value {
-            Some(v) => v,
-            None => self.initialize(i, f),
+        if self.state.get() == State::Alive {
+            self.value.get() as *const T
+        } else {
+            self.initialize(i, f)
         }
     }
 
     #[cold]
     fn initialize(&'static self, i: Option<&mut Option<T>>, f: impl FnOnce() -> T) -> *const T {
         let value = i.and_then(Option::take).unwrap_or_else(f);
-        // Destroy the old value, after updating the TLS variable as the
-        // destructor might reference it.
+
+        // Destroy the old value if it is initialized
         // FIXME(#110897): maybe panic on recursive initialization.
+        if self.state.get() == State::Alive {
+            self.state.set(State::Destroying);
+            // Safety: we check for no initialization during drop below
+            unsafe {
+                ptr::drop_in_place(self.value.get() as *mut T);
+            }
+            self.state.set(State::Initial);
+        }
+
+        // Guard against initialization during drop
+        if self.state.get() == State::Destroying {
+            panic!("Attempted to initialize thread-local while it is being dropped");
+        }
+
         unsafe {
-            self.value.get().replace(Some(value));
+            self.value.get().write(MaybeUninit::new(value));
         }
-        // SAFETY: we just set this to `Some`.
-        unsafe { (*self.value.get()).as_ref().unwrap_unchecked() }
+        self.state.set(State::Alive);
+
+        self.value.get() as *const T
     }
 }
 
diff --git a/library/std/src/sys/thread_local/os.rs b/library/std/src/sys/thread_local/os.rs
index fe6af27db3a..88bb5ae7c65 100644
--- a/library/std/src/sys/thread_local/os.rs
+++ b/library/std/src/sys/thread_local/os.rs
@@ -1,8 +1,12 @@
 use super::key::{Key, LazyKey, get, set};
 use super::{abort_on_dtor_unwind, guard};
+use crate::alloc::{self, Layout};
 use crate::cell::Cell;
 use crate::marker::PhantomData;
-use crate::ptr;
+use crate::mem::ManuallyDrop;
+use crate::ops::Deref;
+use crate::panic::{AssertUnwindSafe, catch_unwind, resume_unwind};
+use crate::ptr::{self, NonNull};
 
 #[doc(hidden)]
 #[allow_internal_unstable(thread_local_internals)]
@@ -10,17 +14,12 @@ use crate::ptr;
 #[unstable(feature = "thread_local_internals", issue = "none")]
 #[rustc_macro_transparency = "semitransparent"]
 pub macro thread_local_inner {
-    // used to generate the `LocalKey` value for const-initialized thread locals
-    (@key $t:ty, const $init:expr) => {
-        $crate::thread::local_impl::thread_local_inner!(@key $t, { const INIT_EXPR: $t = $init; INIT_EXPR })
-    },
-
     // NOTE: we cannot import `Storage` or `LocalKey` with a `use` because that can shadow user
     // provided type or type alias with a matching name. Please update the shadowing test in
     // `tests/thread.rs` if these types are renamed.
 
     // used to generate the `LocalKey` value for `thread_local!`.
-    (@key $t:ty, $init:expr) => {{
+    (@key $t:ty, $($(#[$($align_attr:tt)*])+)?, $init:expr) => {{
         #[inline]
         fn __init() -> $t { $init }
 
@@ -29,37 +28,148 @@ pub macro thread_local_inner {
         // in `tests/thread.rs` if these types are renamed.
         unsafe {
             $crate::thread::LocalKey::new(|init| {
-                static VAL: $crate::thread::local_impl::Storage<$t>
+                static VAL: $crate::thread::local_impl::Storage<$t, {
+                    $({
+                        // Ensure that attributes have valid syntax
+                        // and that the proper feature gate is enabled
+                        $(#[$($align_attr)*])+
+                        #[allow(unused)]
+                        static DUMMY: () = ();
+                    })?
+
+                    #[allow(unused_mut)]
+                    let mut final_align = $crate::thread::local_impl::value_align::<$t>();
+                    $($($crate::thread::local_impl::thread_local_inner!(@align final_align, $($align_attr)*);)+)?
+                    final_align
+                }>
                     = $crate::thread::local_impl::Storage::new();
                 VAL.get(init, __init)
             })
         }
     }},
-    ($(#[$attr:meta])* $vis:vis $name:ident, $t:ty, $($init:tt)*) => {
-        $(#[$attr])* $vis const $name: $crate::thread::LocalKey<$t> =
-            $crate::thread::local_impl::thread_local_inner!(@key $t, $($init)*);
+
+    // process a single `rustc_align_static` attribute
+    (@align $final_align:ident, rustc_align_static($($align:tt)*) $(, $($attr_rest:tt)+)?) => {
+        let new_align: $crate::primitive::usize = $($align)*;
+        if new_align > $final_align {
+            $final_align = new_align;
+        }
+
+        $($crate::thread::local_impl::thread_local_inner!(@align $final_align, $($attr_rest)+);)?
+    },
+
+    // process a single `cfg_attr` attribute
+    // by translating it into a `cfg`ed block and recursing.
+    // https://doc.rust-lang.org/reference/conditional-compilation.html#railroad-ConfigurationPredicate
+
+    (@align $final_align:ident, cfg_attr(true, $($cfg_rhs:tt)*) $(, $($attr_rest:tt)+)?) => {
+        #[cfg(true)]
+        {
+            $crate::thread::local_impl::thread_local_inner!(@align $final_align, $($cfg_rhs)*);
+        }
+
+        $($crate::thread::local_impl::thread_local_inner!(@align $final_align, $($attr_rest)+);)?
+    },
+
+    (@align $final_align:ident, cfg_attr(false, $($cfg_rhs:tt)*) $(, $($attr_rest:tt)+)?) => {
+        #[cfg(false)]
+        {
+            $crate::thread::local_impl::thread_local_inner!(@align $final_align, $($cfg_rhs)*);
+        }
+
+        $($crate::thread::local_impl::thread_local_inner!(@align $final_align, $($attr_rest)+);)?
+    },
+
+    (@align $final_align:ident, cfg_attr($cfg_pred:meta, $($cfg_rhs:tt)*) $(, $($attr_rest:tt)+)?) => {
+        #[cfg($cfg_pred)]
+        {
+            $crate::thread::local_impl::thread_local_inner!(@align $final_align, $($cfg_rhs)*);
+        }
+
+        $($crate::thread::local_impl::thread_local_inner!(@align $final_align, $($attr_rest)+);)?
     },
 }
 
 /// Use a regular global static to store this key; the state provided will then be
 /// thread-local.
+/// INVARIANT: ALIGN must be a valid alignment, and no less than `value_align::<T>`.
 #[allow(missing_debug_implementations)]
-pub struct Storage<T> {
+pub struct Storage<T, const ALIGN: usize> {
     key: LazyKey,
     marker: PhantomData<Cell<T>>,
 }
 
-unsafe impl<T> Sync for Storage<T> {}
+unsafe impl<T, const ALIGN: usize> Sync for Storage<T, ALIGN> {}
 
+#[repr(C)]
 struct Value<T: 'static> {
+    // This field must be first, for correctness of `#[rustc_align_static]`
     value: T,
     // INVARIANT: if this value is stored under a TLS key, `key` must be that `key`.
     key: Key,
 }
 
-impl<T: 'static> Storage<T> {
-    pub const fn new() -> Storage<T> {
-        Storage { key: LazyKey::new(Some(destroy_value::<T>)), marker: PhantomData }
+pub const fn value_align<T: 'static>() -> usize {
+    crate::mem::align_of::<Value<T>>()
+}
+
+/// Equivalent to `Box<Value<T>>`, but potentially over-aligned.
+struct AlignedBox<T: 'static, const ALIGN: usize> {
+    ptr: NonNull<Value<T>>,
+}
+
+impl<T: 'static, const ALIGN: usize> AlignedBox<T, ALIGN> {
+    #[inline]
+    fn new(v: Value<T>) -> Self {
+        let layout = Layout::new::<Value<T>>().align_to(ALIGN).unwrap();
+
+        let ptr: *mut Value<T> = (unsafe { alloc::alloc(layout) }).cast();
+        let Some(ptr) = NonNull::new(ptr) else {
+            alloc::handle_alloc_error(layout);
+        };
+        unsafe { ptr.write(v) };
+        Self { ptr }
+    }
+
+    #[inline]
+    fn into_raw(b: Self) -> *mut Value<T> {
+        let md = ManuallyDrop::new(b);
+        md.ptr.as_ptr()
+    }
+
+    #[inline]
+    unsafe fn from_raw(ptr: *mut Value<T>) -> Self {
+        Self { ptr: unsafe { NonNull::new_unchecked(ptr) } }
+    }
+}
+
+impl<T: 'static, const ALIGN: usize> Deref for AlignedBox<T, ALIGN> {
+    type Target = Value<T>;
+
+    #[inline]
+    fn deref(&self) -> &Self::Target {
+        unsafe { &*(self.ptr.as_ptr()) }
+    }
+}
+
+impl<T: 'static, const ALIGN: usize> Drop for AlignedBox<T, ALIGN> {
+    #[inline]
+    fn drop(&mut self) {
+        let layout = Layout::new::<Value<T>>().align_to(ALIGN).unwrap();
+
+        unsafe {
+            let unwind_result = catch_unwind(AssertUnwindSafe(|| self.ptr.drop_in_place()));
+            alloc::dealloc(self.ptr.as_ptr().cast(), layout);
+            if let Err(payload) = unwind_result {
+                resume_unwind(payload);
+            }
+        }
+    }
+}
+
+impl<T: 'static, const ALIGN: usize> Storage<T, ALIGN> {
+    pub const fn new() -> Storage<T, ALIGN> {
+        Storage { key: LazyKey::new(Some(destroy_value::<T, ALIGN>)), marker: PhantomData }
     }
 
     /// Gets a pointer to the TLS value, potentially initializing it with the
@@ -95,8 +205,11 @@ impl<T: 'static> Storage<T> {
             return ptr::null();
         }
 
-        let value = Box::new(Value { value: i.and_then(Option::take).unwrap_or_else(f), key });
-        let ptr = Box::into_raw(value);
+        let value = AlignedBox::<T, ALIGN>::new(Value {
+            value: i.and_then(Option::take).unwrap_or_else(f),
+            key,
+        });
+        let ptr = AlignedBox::into_raw(value);
 
         // SAFETY:
         // * key came from a `LazyKey` and is thus correct.
@@ -114,7 +227,7 @@ impl<T: 'static> Storage<T> {
             // initializer has already returned and the next scope only starts
             // after we return the pointer. Therefore, there can be no references
             // to the old value.
-            drop(unsafe { Box::from_raw(old) });
+            drop(unsafe { AlignedBox::<T, ALIGN>::from_raw(old) });
         }
 
         // SAFETY: We just created this value above.
@@ -122,7 +235,7 @@ impl<T: 'static> Storage<T> {
     }
 }
 
-unsafe extern "C" fn destroy_value<T: 'static>(ptr: *mut u8) {
+unsafe extern "C" fn destroy_value<T: 'static, const ALIGN: usize>(ptr: *mut u8) {
     // SAFETY:
     //
     // The OS TLS ensures that this key contains a null value when this
@@ -133,7 +246,7 @@ unsafe extern "C" fn destroy_value<T: 'static>(ptr: *mut u8) {
     // Note that to prevent an infinite loop we reset it back to null right
     // before we return from the destructor ourselves.
     abort_on_dtor_unwind(|| {
-        let ptr = unsafe { Box::from_raw(ptr as *mut Value<T>) };
+        let ptr = unsafe { AlignedBox::<T, ALIGN>::from_raw(ptr as *mut Value<T>) };
         let key = ptr.key;
         // SAFETY: `key` is the TLS key `ptr` was stored under.
         unsafe { set(key, ptr::without_provenance_mut(1)) };
diff --git a/library/std/src/thread/local.rs b/library/std/src/thread/local.rs
index 0a6f2e5d508..4259a4d1f3b 100644
--- a/library/std/src/thread/local.rs
+++ b/library/std/src/thread/local.rs
@@ -132,6 +132,216 @@ impl<T: 'static> fmt::Debug for LocalKey<T> {
     }
 }
 
+#[doc(hidden)]
+#[allow_internal_unstable(thread_local_internals)]
+#[unstable(feature = "thread_local_internals", issue = "none")]
+#[rustc_macro_transparency = "semitransparent"]
+pub macro thread_local_process_attrs {
+
+    // Parse `cfg_attr` to figure out whether it's a `rustc_align_static`.
+    // Each `cfg_attr` can have zero or more attributes on the RHS, and can be nested.
+
+    // finished parsing the `cfg_attr`, it had no `rustc_align_static`
+    (
+        [] [$(#[$($prev_other_attrs:tt)*])*];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [] };
+        [$($prev_align_attrs_ret:tt)*] [$($prev_other_attrs_ret:tt)*];
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs_ret)*] [$($prev_other_attrs_ret)* #[cfg_attr($($predicate)*, $($($prev_other_attrs)*),*)]];
+            $($rest)*
+        );
+    ),
+
+    // finished parsing the `cfg_attr`, it had nothing but `rustc_align_static`
+    (
+        [$(#[$($prev_align_attrs:tt)*])+] [];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [] };
+        [$($prev_align_attrs_ret:tt)*] [$($prev_other_attrs_ret:tt)*];
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs_ret)*  #[cfg_attr($($predicate)*, $($($prev_align_attrs)*),+)]] [$($prev_other_attrs_ret)*];
+            $($rest)*
+        );
+    ),
+
+    // finished parsing the `cfg_attr`, it had a mix of `rustc_align_static` and other attrs
+    (
+        [$(#[$($prev_align_attrs:tt)*])+] [$(#[$($prev_other_attrs:tt)*])+];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [] };
+        [$($prev_align_attrs_ret:tt)*] [$($prev_other_attrs_ret:tt)*];
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs_ret)*  #[cfg_attr($($predicate)*, $($($prev_align_attrs)*),+)]] [$($prev_other_attrs_ret)* #[cfg_attr($($predicate)*, $($($prev_other_attrs)*),+)]];
+            $($rest)*
+        );
+    ),
+
+    // it's a `rustc_align_static`
+    (
+        [$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [rustc_align_static($($align_static_args:tt)*) $(, $($attr_rhs:tt)*)?] };
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs)* #[rustc_align_static($($align_static_args)*)]] [$($prev_other_attrs)*];
+            @processing_cfg_attr { pred: ($($predicate)*), rhs: [$($($attr_rhs)*)?] };
+            $($rest)*
+        );
+    ),
+
+    // it's a nested `cfg_attr(true, ...)`; recurse into RHS
+    (
+        [$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [cfg_attr(true, $($cfg_rhs:tt)*) $(, $($attr_rhs:tt)*)?] };
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [] [];
+            @processing_cfg_attr { pred: (true), rhs: [$($cfg_rhs)*] };
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*];
+            @processing_cfg_attr { pred: ($($predicate)*), rhs: [$($($attr_rhs)*)?] };
+            $($rest)*
+        );
+    ),
+
+    // it's a nested `cfg_attr(false, ...)`; recurse into RHS
+    (
+        [$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [cfg_attr(false, $($cfg_rhs:tt)*) $(, $($attr_rhs:tt)*)?] };
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [] [];
+            @processing_cfg_attr { pred: (false), rhs: [$($cfg_rhs)*] };
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*];
+            @processing_cfg_attr { pred: ($($predicate)*), rhs: [$($($attr_rhs)*)?] };
+            $($rest)*
+        );
+    ),
+
+
+    // it's a nested `cfg_attr(..., ...)`; recurse into RHS
+    (
+        [$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [cfg_attr($cfg_lhs:meta, $($cfg_rhs:tt)*) $(, $($attr_rhs:tt)*)?] };
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [] [];
+            @processing_cfg_attr { pred: ($cfg_lhs), rhs: [$($cfg_rhs)*] };
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*];
+            @processing_cfg_attr { pred: ($($predicate)*), rhs: [$($($attr_rhs)*)?] };
+            $($rest)*
+        );
+    ),
+
+    // it's some other attribute
+    (
+        [$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*];
+        @processing_cfg_attr { pred: ($($predicate:tt)*), rhs: [$meta:meta $(, $($attr_rhs:tt)*)?] };
+        $($rest:tt)*
+    ) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs)*] [$($prev_other_attrs)* #[$meta]];
+            @processing_cfg_attr { pred: ($($predicate)*), rhs: [$($($attr_rhs)*)?] };
+            $($rest)*
+        );
+    ),
+
+
+    // Separate attributes into `rustc_align_static` and everything else:
+
+    // `rustc_align_static` attribute
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*]; #[rustc_align_static $($attr_rest:tt)*] $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs)* #[rustc_align_static $($attr_rest)*]] [$($prev_other_attrs)*];
+            $($rest)*
+        );
+    ),
+
+    // `cfg_attr(true, ...)` attribute; parse it
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*]; #[cfg_attr(true, $($cfg_rhs:tt)*)] $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [] [];
+            @processing_cfg_attr { pred: (true), rhs: [$($cfg_rhs)*] };
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*];
+            $($rest)*
+        );
+    ),
+
+    // `cfg_attr(false, ...)` attribute; parse it
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*]; #[cfg_attr(false, $($cfg_rhs:tt)*)] $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [] [];
+            @processing_cfg_attr { pred: (false), rhs: [$($cfg_rhs)*] };
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*];
+            $($rest)*
+        );
+    ),
+
+    // `cfg_attr(..., ...)` attribute; parse it
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*]; #[cfg_attr($cfg_pred:meta, $($cfg_rhs:tt)*)] $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [] [];
+            @processing_cfg_attr { pred: ($cfg_pred), rhs: [$($cfg_rhs)*] };
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*];
+            $($rest)*
+        );
+    ),
+
+    // doc comment not followed by any other attributes; process it all at once to avoid blowing recursion limit
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*]; $(#[doc $($doc_rhs:tt)*])+ $vis:vis static $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs)*] [$($prev_other_attrs)* $(#[doc $($doc_rhs)*])+];
+            $vis static $($rest)*
+        );
+    ),
+
+    // 8 lines of doc comment; process them all at once to avoid blowing recursion limit
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*];
+     #[doc $($doc_rhs_1:tt)*] #[doc $($doc_rhs_2:tt)*] #[doc $($doc_rhs_3:tt)*] #[doc $($doc_rhs_4:tt)*]
+     #[doc $($doc_rhs_5:tt)*] #[doc $($doc_rhs_6:tt)*] #[doc $($doc_rhs_7:tt)*] #[doc $($doc_rhs_8:tt)*]
+     $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs)*] [$($prev_other_attrs)*
+            #[doc $($doc_rhs_1)*] #[doc $($doc_rhs_2)*] #[doc $($doc_rhs_3)*] #[doc $($doc_rhs_4)*]
+            #[doc $($doc_rhs_5)*] #[doc $($doc_rhs_6)*] #[doc $($doc_rhs_7)*] #[doc $($doc_rhs_8)*]];
+            $($rest)*
+        );
+    ),
+
+    // other attribute
+    ([$($prev_align_attrs:tt)*] [$($prev_other_attrs:tt)*]; #[$($attr:tt)*] $($rest:tt)*) => (
+        $crate::thread::local_impl::thread_local_process_attrs!(
+            [$($prev_align_attrs)*] [$($prev_other_attrs)* #[$($attr)*]];
+            $($rest)*
+        );
+    ),
+
+
+    // Delegate to `thread_local_inner` once attributes are fully categorized:
+
+    // process `const` declaration and recurse
+    ([$($align_attrs:tt)*] [$($other_attrs:tt)*]; $vis:vis static $name:ident: $t:ty = const $init:block $(; $($($rest:tt)+)?)?) => (
+        $($other_attrs)* $vis const $name: $crate::thread::LocalKey<$t> =
+            $crate::thread::local_impl::thread_local_inner!(@key $t, $($align_attrs)*, const $init);
+
+        $($($crate::thread::local_impl::thread_local_process_attrs!([] []; $($rest)+);)?)?
+    ),
+
+    // process non-`const` declaration and recurse
+    ([$($align_attrs:tt)*] [$($other_attrs:tt)*]; $vis:vis static $name:ident: $t:ty = $init:expr $(; $($($rest:tt)+)?)?) => (
+        $($other_attrs)* $vis const $name: $crate::thread::LocalKey<$t> =
+            $crate::thread::local_impl::thread_local_inner!(@key $t, $($align_attrs)*, $init);
+
+        $($($crate::thread::local_impl::thread_local_process_attrs!([] []; $($rest)+);)?)?
+    ),
+}
+
 /// Declare a new thread local storage key of type [`std::thread::LocalKey`].
 ///
 /// # Syntax
@@ -182,28 +392,11 @@ impl<T: 'static> fmt::Debug for LocalKey<T> {
 #[cfg_attr(not(test), rustc_diagnostic_item = "thread_local_macro")]
 #[allow_internal_unstable(thread_local_internals)]
 macro_rules! thread_local {
-    // empty (base case for the recursion)
     () => {};
 
-    ($(#[$attr:meta])* $vis:vis static $name:ident: $t:ty = const $init:block; $($rest:tt)*) => (
-        $crate::thread::local_impl::thread_local_inner!($(#[$attr])* $vis $name, $t, const $init);
-        $crate::thread_local!($($rest)*);
-    );
-
-    ($(#[$attr:meta])* $vis:vis static $name:ident: $t:ty = const $init:block) => (
-        $crate::thread::local_impl::thread_local_inner!($(#[$attr])* $vis $name, $t, const $init);
-    );
-
-    // process multiple declarations
-    ($(#[$attr:meta])* $vis:vis static $name:ident: $t:ty = $init:expr; $($rest:tt)*) => (
-        $crate::thread::local_impl::thread_local_inner!($(#[$attr])* $vis $name, $t, $init);
-        $crate::thread_local!($($rest)*);
-    );
-
-    // handle a single declaration
-    ($(#[$attr:meta])* $vis:vis static $name:ident: $t:ty = $init:expr) => (
-        $crate::thread::local_impl::thread_local_inner!($(#[$attr])* $vis $name, $t, $init);
-    );
+    ($($tt:tt)+) => {
+        $crate::thread::local_impl::thread_local_process_attrs!([] []; $($tt)+);
+    };
 }
 
 /// An error returned by [`LocalKey::try_with`](struct.LocalKey.html#method.try_with).
diff --git a/library/std/src/thread/mod.rs b/library/std/src/thread/mod.rs
index 1768369792a..fd7cce3f97d 100644
--- a/library/std/src/thread/mod.rs
+++ b/library/std/src/thread/mod.rs
@@ -207,6 +207,7 @@ pub use self::local::{AccessError, LocalKey};
 #[doc(hidden)]
 #[unstable(feature = "thread_local_internals", issue = "none")]
 pub mod local_impl {
+    pub use super::local::thread_local_process_attrs;
     pub use crate::sys::thread_local::*;
 }
 
diff --git a/library/std/tests/thread.rs b/library/std/tests/thread.rs
index 29f220d8a70..dc8eadd7514 100644
--- a/library/std/tests/thread.rs
+++ b/library/std/tests/thread.rs
@@ -66,6 +66,8 @@ fn thread_local_hygeiene() {
     type Storage = ();
     type LazyStorage = ();
     type EagerStorage = ();
+    #[allow(non_camel_case_types)]
+    type usize = ();
     thread_local! {
         static A: LocalKey = const { () };
         static B: Storage = const { () };
diff --git a/src/bootstrap/defaults/bootstrap.dist.toml b/src/bootstrap/defaults/bootstrap.dist.toml
index b111a20f8d8..bb0592ce947 100644
--- a/src/bootstrap/defaults/bootstrap.dist.toml
+++ b/src/bootstrap/defaults/bootstrap.dist.toml
@@ -7,8 +7,6 @@ test-stage = 2
 doc-stage = 2
 # When compiling from source, you usually want all tools.
 extended = true
-# Use libtest built from the source tree instead of the precompiled one from stage 0.
-compiletest-use-stage0-libtest = false
 
 # Most users installing from source want to build all parts of the project from source.
 [llvm]
diff --git a/src/bootstrap/src/core/builder/mod.rs b/src/bootstrap/src/core/builder/mod.rs
index 006dea4b98d..fc06db8f80b 100644
--- a/src/bootstrap/src/core/builder/mod.rs
+++ b/src/bootstrap/src/core/builder/mod.rs
@@ -1145,7 +1145,7 @@ impl<'a> Builder<'a> {
                 test::RunMakeCargo,
             ),
             Kind::Miri => describe!(test::Crate),
-            Kind::Bench => describe!(test::Crate, test::CrateLibrustc),
+            Kind::Bench => describe!(test::Crate, test::CrateLibrustc, test::CrateRustdoc),
             Kind::Doc => describe!(
                 doc::UnstableBook,
                 doc::UnstableBookGen,
diff --git a/src/ci/citool/Cargo.toml b/src/ci/citool/Cargo.toml
index f61243a4d71..078b877e44b 100644
--- a/src/ci/citool/Cargo.toml
+++ b/src/ci/citool/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "citool"
 version = "0.1.0"
-edition = "2021"
+edition = "2024"
 
 [dependencies]
 anyhow = "1"
diff --git a/src/ci/citool/src/main.rs b/src/ci/citool/src/main.rs
index fe1b36673a1..255d39846da 100644
--- a/src/ci/citool/src/main.rs
+++ b/src/ci/citool/src/main.rs
@@ -24,7 +24,7 @@ use crate::github::JobInfoResolver;
 use crate::jobs::RunType;
 use crate::metrics::{JobMetrics, download_auto_job_metrics, download_job_metrics, load_metrics};
 use crate::test_dashboard::generate_test_dashboard;
-use crate::utils::{load_env_var, output_details};
+use crate::utils::{init_submodule_if_needed, load_env_var, output_details};
 
 const CI_DIRECTORY: &str = concat!(env!("CARGO_MANIFEST_DIR"), "/..");
 pub const DOCKER_DIRECTORY: &str = concat!(env!("CARGO_MANIFEST_DIR"), "/../docker");
@@ -121,6 +121,8 @@ fn run_workflow_locally(db: JobDatabase, job_type: JobType, name: String) -> any
         (key.clone(), value)
     }));
 
+    init_submodule_if_needed("src/llvm-project/")?;
+
     let mut cmd = Command::new(Path::new(DOCKER_DIRECTORY).join("run.sh"));
     cmd.arg(job.image());
     cmd.envs(custom_env);
diff --git a/src/ci/citool/src/utils.rs b/src/ci/citool/src/utils.rs
index 3176cb62f60..43b220255dc 100644
--- a/src/ci/citool/src/utils.rs
+++ b/src/ci/citool/src/utils.rs
@@ -1,5 +1,7 @@
 use std::borrow::Cow;
+use std::convert::AsRef;
 use std::path::Path;
+use std::process::Command;
 
 use anyhow::Context;
 
@@ -34,3 +36,19 @@ where
 pub fn normalize_path_delimiters(name: &str) -> Cow<'_, str> {
     if name.contains("\\") { name.replace('\\', "/").into() } else { name.into() }
 }
+
+pub fn init_submodule_if_needed<P: AsRef<Path>>(path_to_submodule: P) -> anyhow::Result<()> {
+    let path_to_submodule = path_to_submodule.as_ref();
+
+    if let Ok(mut iter) = path_to_submodule.read_dir()
+        && iter.any(|entry| entry.is_ok())
+    {
+        // Seems like the submodule is already initialized, nothing to be done here.
+        return Ok(());
+    }
+    let mut child = Command::new("git")
+        .args(&["submodule", "update", "--init"])
+        .arg(path_to_submodule)
+        .spawn()?;
+    if !child.wait()?.success() { Err(anyhow::anyhow!("git command failed")) } else { Ok(()) }
+}
diff --git a/src/ci/citool/tests/test-jobs.yml b/src/ci/citool/tests/test-jobs.yml
index d82b3e7648e..512c8062857 100644
--- a/src/ci/citool/tests/test-jobs.yml
+++ b/src/ci/citool/tests/test-jobs.yml
@@ -27,7 +27,7 @@ runners:
     <<: *base-job
 envs:
   env-x86_64-apple-tests: &env-x86_64-apple-tests
-    SCRIPT: ./x.py check compiletest --set build.compiletest-use-stage0-libtest=true && ./x.py --stage 2 test --skip tests/ui --skip tests/rustdoc -- --exact
+    SCRIPT: ./x.py check compiletest && ./x.py --stage 2 test --skip tests/ui --skip tests/rustdoc -- --exact
     RUST_CONFIGURE_ARGS: --build=x86_64-apple-darwin --enable-sanitizers --enable-profiler --set rust.jemalloc
     RUSTC_RETRY_LINKER_ON_SEGFAULT: 1
     # Ensure that host tooling is tested on our minimum supported macOS version.
diff --git a/src/ci/docker/host-x86_64/pr-check-1/Dockerfile b/src/ci/docker/host-x86_64/pr-check-1/Dockerfile
index 04ac0f33daf..776bbb12e44 100644
--- a/src/ci/docker/host-x86_64/pr-check-1/Dockerfile
+++ b/src/ci/docker/host-x86_64/pr-check-1/Dockerfile
@@ -43,7 +43,6 @@ ENV SCRIPT \
   python3 ../x.py check bootstrap && \
   /scripts/check-default-config-profiles.sh && \
   python3 ../x.py build src/tools/build-manifest && \
-  python3 ../x.py check compiletest --set build.compiletest-use-stage0-libtest=true && \
   python3 ../x.py check --target=i686-pc-windows-gnu --host=i686-pc-windows-gnu && \
   python3 ../x.py check --set build.optimized-compiler-builtins=false core alloc std --target=aarch64-unknown-linux-gnu,i686-pc-windows-msvc,i686-unknown-linux-gnu,x86_64-apple-darwin,x86_64-pc-windows-gnu,x86_64-pc-windows-msvc && \
   /scripts/validate-toolstate.sh && \
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
index 95357d22937..278e40eb71f 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
@@ -90,5 +90,4 @@ ENV HOST_TARGET x86_64-unknown-linux-gnu
 COPY scripts/shared.sh /scripts/
 
 ENV SCRIPT /tmp/checktools.sh ../x.py && \
-  python3 ../x.py check compiletest --set build.compiletest-use-stage0-libtest=true && \
   python3 ../x.py test tests/rustdoc-gui --stage 2 --test-args "'--jobs 1'"
diff --git a/src/doc/rustc/src/lints/levels.md b/src/doc/rustc/src/lints/levels.md
index 5b002b435a5..09b55da741d 100644
--- a/src/doc/rustc/src/lints/levels.md
+++ b/src/doc/rustc/src/lints/levels.md
@@ -38,7 +38,7 @@ talk about later in this section.
 
 Sometimes, it can be helpful to suppress lints, but at the same time ensure that
 the code in question still emits them. The 'expect' level does exactly this. If
-the lint in question is not emitted, the `unfulfilled_lint_expectation` lint
+the lint in question is not emitted, the `unfulfilled_lint_expectations` lint
 triggers on the `expect` attribute, notifying you that the expectation is no
 longer fulfilled.
 
diff --git a/src/etc/lldb_providers.py b/src/etc/lldb_providers.py
index 65f18baa937..3eb964d2fba 100644
--- a/src/etc/lldb_providers.py
+++ b/src/etc/lldb_providers.py
@@ -761,7 +761,8 @@ class MSVCTupleSyntheticProvider:
 
     def get_child_at_index(self, index: int) -> SBValue:
         child: SBValue = self.valobj.GetChildAtIndex(index)
-        return child.CreateChildAtOffset(str(index), 0, child.GetType())
+        offset = self.valobj.GetType().GetFieldAtIndex(index).byte_offset
+        return self.valobj.CreateChildAtOffset(str(index), offset, child.GetType())
 
     def update(self):
         pass
@@ -772,7 +773,7 @@ class MSVCTupleSyntheticProvider:
     def get_type_name(self) -> str:
         name = self.valobj.GetTypeName()
         # remove "tuple$<" and ">", str.removeprefix and str.removesuffix require python 3.9+
-        name = name[7:-1]
+        name = name[7:-1].strip()
         return "(" + name + ")"
 
 
diff --git a/src/librustdoc/html/highlight.rs b/src/librustdoc/html/highlight.rs
index fad15573cde..1dcb4dcc3ff 100644
--- a/src/librustdoc/html/highlight.rs
+++ b/src/librustdoc/html/highlight.rs
@@ -12,15 +12,16 @@ use std::iter;
 
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_lexer::{Cursor, FrontmatterAllowed, LiteralKind, TokenKind};
+use rustc_span::BytePos;
 use rustc_span::edition::Edition;
 use rustc_span::symbol::Symbol;
-use rustc_span::{BytePos, DUMMY_SP, Span};
 
 use super::format;
 use crate::clean::PrimitiveType;
 use crate::display::Joined as _;
 use crate::html::escape::EscapeBodyText;
 use crate::html::macro_expansion::ExpandedCode;
+use crate::html::render::span_map::{DUMMY_SP, Span};
 use crate::html::render::{Context, LinkFromSrc};
 
 /// This type is needed in case we want to render links on items to allow to go to their definition.
diff --git a/src/librustdoc/html/highlight/tests.rs b/src/librustdoc/html/highlight/tests.rs
index 2603e887bea..4d1bee9b3a1 100644
--- a/src/librustdoc/html/highlight/tests.rs
+++ b/src/librustdoc/html/highlight/tests.rs
@@ -1,6 +1,7 @@
 use expect_test::expect_file;
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_span::create_default_session_globals_then;
+use test::Bencher;
 
 use super::{DecorationInfo, write_code};
 
@@ -81,3 +82,16 @@ let a = 4;";
         expect_file!["fixtures/decorations.html"].assert_eq(&html);
     });
 }
+
+#[bench]
+fn bench_html_highlighting(b: &mut Bencher) {
+    let src = include_str!("../../../../compiler/rustc_ast/src/visit.rs");
+
+    create_default_session_globals_then(|| {
+        b.iter(|| {
+            let mut out = String::new();
+            write_code(&mut out, src, None, None, None);
+            out
+        });
+    });
+}
diff --git a/src/librustdoc/html/render/context.rs b/src/librustdoc/html/render/context.rs
index 5f92ab2fada..4c06d0da470 100644
--- a/src/librustdoc/html/render/context.rs
+++ b/src/librustdoc/html/render/context.rs
@@ -30,6 +30,7 @@ use crate::formats::item_type::ItemType;
 use crate::html::escape::Escape;
 use crate::html::macro_expansion::ExpandedCode;
 use crate::html::markdown::{self, ErrorCodes, IdMap, plain_text_summary};
+use crate::html::render::span_map::Span;
 use crate::html::render::write_shared::write_shared;
 use crate::html::url_parts_builder::UrlPartsBuilder;
 use crate::html::{layout, sources, static_files};
@@ -139,7 +140,7 @@ pub(crate) struct SharedContext<'tcx> {
 
     /// Correspondence map used to link types used in the source code pages to allow to click on
     /// links to jump to the type's definition.
-    pub(crate) span_correspondence_map: FxHashMap<rustc_span::Span, LinkFromSrc>,
+    pub(crate) span_correspondence_map: FxHashMap<Span, LinkFromSrc>,
     pub(crate) expanded_codes: FxHashMap<BytePos, Vec<ExpandedCode>>,
     /// The [`Cache`] used during rendering.
     pub(crate) cache: Cache,
diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs
index 97dcaf57cdf..d6371e4dbab 100644
--- a/src/librustdoc/html/render/mod.rs
+++ b/src/librustdoc/html/render/mod.rs
@@ -36,7 +36,7 @@ mod ordered_json;
 mod print_item;
 pub(crate) mod sidebar;
 mod sorted_template;
-mod span_map;
+pub(crate) mod span_map;
 mod type_layout;
 mod write_shared;
 
diff --git a/src/librustdoc/html/render/span_map.rs b/src/librustdoc/html/render/span_map.rs
index ef7ce33298d..bc9417b1bb1 100644
--- a/src/librustdoc/html/render/span_map.rs
+++ b/src/librustdoc/html/render/span_map.rs
@@ -8,11 +8,48 @@ use rustc_hir::{ExprKind, HirId, Item, ItemKind, Mod, Node, QPath};
 use rustc_middle::hir::nested_filter;
 use rustc_middle::ty::TyCtxt;
 use rustc_span::hygiene::MacroKind;
-use rustc_span::{BytePos, ExpnKind, Span};
+use rustc_span::{BytePos, ExpnKind};
 
 use crate::clean::{self, PrimitiveType, rustc_span};
 use crate::html::sources;
 
+/// This is a stripped down version of [`rustc_span::Span`] that only contains the start and end byte positions of the span.
+///
+/// Profiling showed that the `Span` interner was taking up a lot of the run-time when highlighting, and since we
+/// never actually use the context and parent that are stored in a normal `Span`, we can replace its usages with this
+/// one, which is much cheaper to construct.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub(crate) struct Span {
+    lo: BytePos,
+    hi: BytePos,
+}
+
+impl From<rustc_span::Span> for Span {
+    fn from(value: rustc_span::Span) -> Self {
+        Self { lo: value.lo(), hi: value.hi() }
+    }
+}
+
+impl Span {
+    pub(crate) fn lo(self) -> BytePos {
+        self.lo
+    }
+
+    pub(crate) fn hi(self) -> BytePos {
+        self.hi
+    }
+
+    pub(crate) fn with_lo(self, lo: BytePos) -> Self {
+        Self { lo, hi: self.hi() }
+    }
+
+    pub(crate) fn with_hi(self, hi: BytePos) -> Self {
+        Self { lo: self.lo(), hi }
+    }
+}
+
+pub(crate) const DUMMY_SP: Span = Span { lo: BytePos(0), hi: BytePos(0) };
+
 /// This enum allows us to store two different kinds of information:
 ///
 /// In case the `span` definition comes from the same crate, we can simply get the `span` and use
@@ -96,7 +133,7 @@ impl SpanMapVisitor<'_> {
                         })
                         .unwrap_or(path.span)
                 };
-                self.matches.insert(span, link);
+                self.matches.insert(span.into(), link);
             }
             Res::Local(_) if let Some(span) = self.tcx.hir_res_span(path.res) => {
                 let path_span = if only_use_last_segment
@@ -106,11 +143,12 @@ impl SpanMapVisitor<'_> {
                 } else {
                     path.span
                 };
-                self.matches.insert(path_span, LinkFromSrc::Local(clean::Span::new(span)));
+                self.matches.insert(path_span.into(), LinkFromSrc::Local(clean::Span::new(span)));
             }
             Res::PrimTy(p) => {
                 // FIXME: Doesn't handle "path-like" primitives like arrays or tuples.
-                self.matches.insert(path.span, LinkFromSrc::Primitive(PrimitiveType::from(p)));
+                self.matches
+                    .insert(path.span.into(), LinkFromSrc::Primitive(PrimitiveType::from(p)));
             }
             Res::Err => {}
             _ => {}
@@ -127,7 +165,7 @@ impl SpanMapVisitor<'_> {
             if cspan.inner().is_dummy() || cspan.cnum(self.tcx.sess) != LOCAL_CRATE {
                 return;
             }
-            self.matches.insert(span, LinkFromSrc::Doc(item.owner_id.to_def_id()));
+            self.matches.insert(span.into(), LinkFromSrc::Doc(item.owner_id.to_def_id()));
         }
     }
 
@@ -138,7 +176,7 @@ impl SpanMapVisitor<'_> {
     /// so, we loop until we find the macro definition by using `outer_expn_data` in a loop.
     /// Finally, we get the information about the macro itself (`span` if "local", `DefId`
     /// otherwise) and store it inside the span map.
-    fn handle_macro(&mut self, span: Span) -> bool {
+    fn handle_macro(&mut self, span: rustc_span::Span) -> bool {
         if !span.from_expansion() {
             return false;
         }
@@ -176,7 +214,7 @@ impl SpanMapVisitor<'_> {
         // The "call_site" includes the whole macro with its "arguments". We only want
         // the macro name.
         let new_span = new_span.with_hi(new_span.lo() + BytePos(macro_name.len() as u32));
-        self.matches.insert(new_span, link_from_src);
+        self.matches.insert(new_span.into(), link_from_src);
         true
     }
 
@@ -233,7 +271,7 @@ impl<'tcx> Visitor<'tcx> for SpanMapVisitor<'tcx> {
         intravisit::walk_path(self, path);
     }
 
-    fn visit_qpath(&mut self, qpath: &QPath<'tcx>, id: HirId, _span: Span) {
+    fn visit_qpath(&mut self, qpath: &QPath<'tcx>, id: HirId, _span: rustc_span::Span) {
         match *qpath {
             QPath::TypeRelative(qself, path) => {
                 if matches!(path.res, Res::Err) {
@@ -249,7 +287,7 @@ impl<'tcx> Visitor<'tcx> for SpanMapVisitor<'tcx> {
                         self.handle_path(&path, false);
                     }
                 } else {
-                    self.infer_id(path.hir_id, Some(id), path.ident.span);
+                    self.infer_id(path.hir_id, Some(id), path.ident.span.into());
                 }
 
                 rustc_ast::visit::try_visit!(self.visit_ty_unambig(qself));
@@ -267,7 +305,7 @@ impl<'tcx> Visitor<'tcx> for SpanMapVisitor<'tcx> {
         }
     }
 
-    fn visit_mod(&mut self, m: &'tcx Mod<'tcx>, span: Span, id: HirId) {
+    fn visit_mod(&mut self, m: &'tcx Mod<'tcx>, span: rustc_span::Span, id: HirId) {
         // To make the difference between "mod foo {}" and "mod foo;". In case we "import" another
         // file, we want to link to it. Otherwise no need to create a link.
         if !span.overlaps(m.spans.inner_span) {
@@ -275,8 +313,10 @@ impl<'tcx> Visitor<'tcx> for SpanMapVisitor<'tcx> {
             // name only and not all the "mod foo;".
             if let Node::Item(item) = self.tcx.hir_node(id) {
                 let (ident, _) = item.expect_mod();
-                self.matches
-                    .insert(ident.span, LinkFromSrc::Local(clean::Span::new(m.spans.inner_span)));
+                self.matches.insert(
+                    ident.span.into(),
+                    LinkFromSrc::Local(clean::Span::new(m.spans.inner_span)),
+                );
             }
         } else {
             // If it's a "mod foo {}", we want to look to its documentation page.
@@ -288,9 +328,9 @@ impl<'tcx> Visitor<'tcx> for SpanMapVisitor<'tcx> {
     fn visit_expr(&mut self, expr: &'tcx rustc_hir::Expr<'tcx>) {
         match expr.kind {
             ExprKind::MethodCall(segment, ..) => {
-                self.infer_id(segment.hir_id, Some(expr.hir_id), segment.ident.span)
+                self.infer_id(segment.hir_id, Some(expr.hir_id), segment.ident.span.into())
             }
-            ExprKind::Call(call, ..) => self.infer_id(call.hir_id, None, call.span),
+            ExprKind::Call(call, ..) => self.infer_id(call.hir_id, None, call.span.into()),
             _ => {
                 if self.handle_macro(expr.span) {
                     // We don't want to go deeper into the macro.
diff --git a/src/librustdoc/html/sources.rs b/src/librustdoc/html/sources.rs
index 9c5518a780e..c79f63fbc20 100644
--- a/src/librustdoc/html/sources.rs
+++ b/src/librustdoc/html/sources.rs
@@ -348,7 +348,12 @@ pub(crate) fn print_src(
         highlight::write_code(
             fmt,
             s,
-            Some(highlight::HrefContext { context, file_span, root_path, current_href }),
+            Some(highlight::HrefContext {
+                context,
+                file_span: file_span.into(),
+                root_path,
+                current_href,
+            }),
             Some(decoration_info),
             Some(line_info),
         );
diff --git a/src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs b/src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs
index 2bda6d50373..cc98fac45c7 100644
--- a/src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs
+++ b/src/tools/clippy/clippy_utils/src/qualify_min_const_fn.rs
@@ -141,7 +141,8 @@ fn check_rvalue<'tcx>(
             | CastKind::FloatToFloat
             | CastKind::FnPtrToPtr
             | CastKind::PtrToPtr
-            | CastKind::PointerCoercion(PointerCoercion::MutToConstPointer | PointerCoercion::ArrayToPointer, _),
+            | CastKind::PointerCoercion(PointerCoercion::MutToConstPointer | PointerCoercion::ArrayToPointer, _)
+            | CastKind::Subtype,
             operand,
             _,
         ) => check_operand(cx, operand, span, body, msrv),
@@ -312,7 +313,6 @@ fn check_place<'tcx>(
             | ProjectionElem::OpaqueCast(..)
             | ProjectionElem::Downcast(..)
             | ProjectionElem::Subslice { .. }
-            | ProjectionElem::Subtype(_)
             | ProjectionElem::Index(_)
             | ProjectionElem::UnwrapUnsafeBinder(_) => {},
         }
diff --git a/src/tools/compiletest/src/directives.rs b/src/tools/compiletest/src/directives.rs
index e84a2278766..0d85e76c2cc 100644
--- a/src/tools/compiletest/src/directives.rs
+++ b/src/tools/compiletest/src/directives.rs
@@ -63,9 +63,10 @@ impl EarlyProps {
             &mut poisoned,
             testfile,
             rdr,
-            &mut |DirectiveLine { line_number, raw_directive: ln, .. }| {
-                parse_and_update_aux(config, ln, testfile, line_number, &mut props.aux);
-                config.parse_and_update_revisions(testfile, line_number, ln, &mut props.revisions);
+            // (dummy comment to force args into vertical layout)
+            &mut |ref ln: DirectiveLine<'_>| {
+                parse_and_update_aux(config, ln, testfile, &mut props.aux);
+                config.parse_and_update_revisions(testfile, ln, &mut props.revisions);
             },
         );
 
@@ -367,8 +368,8 @@ impl TestProps {
                 &mut poisoned,
                 testfile,
                 file,
-                &mut |directive @ DirectiveLine { line_number, raw_directive: ln, .. }| {
-                    if !directive.applies_to_test_revision(test_revision) {
+                &mut |ref ln: DirectiveLine<'_>| {
+                    if !ln.applies_to_test_revision(test_revision) {
                         return;
                     }
 
@@ -378,7 +379,6 @@ impl TestProps {
                         ln,
                         ERROR_PATTERN,
                         testfile,
-                        line_number,
                         &mut self.error_patterns,
                         |r| r,
                     );
@@ -386,7 +386,6 @@ impl TestProps {
                         ln,
                         REGEX_ERROR_PATTERN,
                         testfile,
-                        line_number,
                         &mut self.regex_error_patterns,
                         |r| r,
                     );
@@ -395,7 +394,6 @@ impl TestProps {
                         ln,
                         DOC_FLAGS,
                         testfile,
-                        line_number,
                         &mut self.doc_flags,
                         |r| r,
                     );
@@ -414,50 +412,47 @@ impl TestProps {
                     }
 
                     if let Some(flags) =
-                        config.parse_name_value_directive(ln, COMPILE_FLAGS, testfile, line_number)
+                        config.parse_name_value_directive(ln, COMPILE_FLAGS, testfile)
                     {
                         let flags = split_flags(&flags);
-                        for flag in &flags {
+                        for (i, flag) in flags.iter().enumerate() {
                             if flag == "--edition" || flag.starts_with("--edition=") {
                                 panic!("you must use `//@ edition` to configure the edition");
                             }
+                            if (flag == "-C"
+                                && flags.get(i + 1).is_some_and(|v| v.starts_with("incremental=")))
+                                || flag.starts_with("-Cincremental=")
+                            {
+                                panic!(
+                                    "you must use `//@ incremental` to enable incremental compilation"
+                                );
+                            }
                         }
                         self.compile_flags.extend(flags);
                     }
                     if config
-                        .parse_name_value_directive(
-                            ln,
-                            INCORRECT_COMPILER_FLAGS,
-                            testfile,
-                            line_number,
-                        )
+                        .parse_name_value_directive(ln, INCORRECT_COMPILER_FLAGS, testfile)
                         .is_some()
                     {
                         panic!("`compiler-flags` directive should be spelled `compile-flags`");
                     }
 
-                    if let Some(edition) = config.parse_edition(ln, testfile, line_number) {
+                    if let Some(edition) = config.parse_edition(ln, testfile) {
                         // The edition is added at the start, since flags from //@compile-flags must
                         // be passed to rustc last.
                         self.compile_flags.insert(0, format!("--edition={}", edition.trim()));
                         has_edition = true;
                     }
 
-                    config.parse_and_update_revisions(
-                        testfile,
-                        line_number,
-                        ln,
-                        &mut self.revisions,
-                    );
+                    config.parse_and_update_revisions(testfile, ln, &mut self.revisions);
 
-                    if let Some(flags) =
-                        config.parse_name_value_directive(ln, RUN_FLAGS, testfile, line_number)
+                    if let Some(flags) = config.parse_name_value_directive(ln, RUN_FLAGS, testfile)
                     {
                         self.run_flags.extend(split_flags(&flags));
                     }
 
                     if self.pp_exact.is_none() {
-                        self.pp_exact = config.parse_pp_exact(ln, testfile, line_number);
+                        self.pp_exact = config.parse_pp_exact(ln, testfile);
                     }
 
                     config.set_name_directive(ln, SHOULD_ICE, &mut self.should_ice);
@@ -479,9 +474,7 @@ impl TestProps {
                     );
                     config.set_name_directive(ln, NO_PREFER_DYNAMIC, &mut self.no_prefer_dynamic);
 
-                    if let Some(m) =
-                        config.parse_name_value_directive(ln, PRETTY_MODE, testfile, line_number)
-                    {
+                    if let Some(m) = config.parse_name_value_directive(ln, PRETTY_MODE, testfile) {
                         self.pretty_mode = m;
                     }
 
@@ -492,13 +485,12 @@ impl TestProps {
                     );
 
                     // Call a helper method to deal with aux-related directives.
-                    parse_and_update_aux(config, ln, testfile, line_number, &mut self.aux);
+                    parse_and_update_aux(config, ln, testfile, &mut self.aux);
 
                     config.push_name_value_directive(
                         ln,
                         EXEC_ENV,
                         testfile,
-                        line_number,
                         &mut self.exec_env,
                         Config::parse_env,
                     );
@@ -506,7 +498,6 @@ impl TestProps {
                         ln,
                         UNSET_EXEC_ENV,
                         testfile,
-                        line_number,
                         &mut self.unset_exec_env,
                         |r| r.trim().to_owned(),
                     );
@@ -514,7 +505,6 @@ impl TestProps {
                         ln,
                         RUSTC_ENV,
                         testfile,
-                        line_number,
                         &mut self.rustc_env,
                         Config::parse_env,
                     );
@@ -522,7 +512,6 @@ impl TestProps {
                         ln,
                         UNSET_RUSTC_ENV,
                         testfile,
-                        line_number,
                         &mut self.unset_rustc_env,
                         |r| r.trim().to_owned(),
                     );
@@ -530,7 +519,6 @@ impl TestProps {
                         ln,
                         FORBID_OUTPUT,
                         testfile,
-                        line_number,
                         &mut self.forbid_output,
                         |r| r,
                     );
@@ -566,7 +554,7 @@ impl TestProps {
                     }
 
                     if let Some(code) = config
-                        .parse_name_value_directive(ln, FAILURE_STATUS, testfile, line_number)
+                        .parse_name_value_directive(ln, FAILURE_STATUS, testfile)
                         .and_then(|code| code.trim().parse::<i32>().ok())
                     {
                         self.failure_status = Some(code);
@@ -588,7 +576,6 @@ impl TestProps {
                         ln,
                         ASSEMBLY_OUTPUT,
                         testfile,
-                        line_number,
                         &mut self.assembly_output,
                         |r| r.trim().to_string(),
                     );
@@ -602,7 +589,7 @@ impl TestProps {
                     // Unlike the other `name_value_directive`s this needs to be handled manually,
                     // because it sets a `bool` flag.
                     if let Some(known_bug) =
-                        config.parse_name_value_directive(ln, KNOWN_BUG, testfile, line_number)
+                        config.parse_name_value_directive(ln, KNOWN_BUG, testfile)
                     {
                         let known_bug = known_bug.trim();
                         if known_bug == "unknown"
@@ -632,24 +619,20 @@ impl TestProps {
                         ln,
                         TEST_MIR_PASS,
                         testfile,
-                        line_number,
                         &mut self.mir_unit_test,
                         |s| s.trim().to_string(),
                     );
                     config.set_name_directive(ln, REMAP_SRC_BASE, &mut self.remap_src_base);
 
                     if let Some(flags) =
-                        config.parse_name_value_directive(ln, LLVM_COV_FLAGS, testfile, line_number)
+                        config.parse_name_value_directive(ln, LLVM_COV_FLAGS, testfile)
                     {
                         self.llvm_cov_flags.extend(split_flags(&flags));
                     }
 
-                    if let Some(flags) = config.parse_name_value_directive(
-                        ln,
-                        FILECHECK_FLAGS,
-                        testfile,
-                        line_number,
-                    ) {
+                    if let Some(flags) =
+                        config.parse_name_value_directive(ln, FILECHECK_FLAGS, testfile)
+                    {
                         self.filecheck_flags.extend(split_flags(&flags));
                     }
 
@@ -661,7 +644,6 @@ impl TestProps {
                         ln,
                         directives::CORE_STUBS_COMPILE_FLAGS,
                         testfile,
-                        line_number,
                     ) {
                         let flags = split_flags(&flags);
                         for flag in &flags {
@@ -672,12 +654,9 @@ impl TestProps {
                         self.core_stubs_compile_flags.extend(flags);
                     }
 
-                    if let Some(err_kind) = config.parse_name_value_directive(
-                        ln,
-                        DONT_REQUIRE_ANNOTATIONS,
-                        testfile,
-                        line_number,
-                    ) {
+                    if let Some(err_kind) =
+                        config.parse_name_value_directive(ln, DONT_REQUIRE_ANNOTATIONS, testfile)
+                    {
                         self.dont_require_annotations
                             .insert(ErrorKind::expect_from_user_str(err_kind.trim()));
                     }
@@ -734,7 +713,7 @@ impl TestProps {
         }
     }
 
-    fn update_fail_mode(&mut self, ln: &str, config: &Config) {
+    fn update_fail_mode(&mut self, ln: &DirectiveLine<'_>, config: &Config) {
         let check_ui = |mode: &str| {
             // Mode::Crashes may need build-fail in order to trigger llvm errors or stack overflows
             if config.mode != TestMode::Ui && config.mode != TestMode::Crashes {
@@ -769,7 +748,12 @@ impl TestProps {
         }
     }
 
-    fn update_pass_mode(&mut self, ln: &str, revision: Option<&str>, config: &Config) {
+    fn update_pass_mode(
+        &mut self,
+        ln: &DirectiveLine<'_>,
+        revision: Option<&str>,
+        config: &Config,
+    ) {
         let check_no_run = |s| match (config.mode, s) {
             (TestMode::Ui, _) => (),
             (TestMode::Crashes, _) => (),
@@ -814,7 +798,7 @@ impl TestProps {
         self.pass_mode
     }
 
-    pub fn update_add_core_stubs(&mut self, ln: &str, config: &Config) {
+    fn update_add_core_stubs(&mut self, ln: &DirectiveLine<'_>, config: &Config) {
         let add_core_stubs = config.parse_name_directive(ln, directives::ADD_CORE_STUBS);
         if add_core_stubs {
             if !matches!(config.mode, TestMode::Ui | TestMode::Codegen | TestMode::Assembly) {
@@ -905,10 +889,12 @@ pub(crate) struct CheckDirectiveResult<'ln> {
     trailing_directive: Option<&'ln str>,
 }
 
-pub(crate) fn check_directive<'a>(
-    directive_ln: &'a str,
+fn check_directive<'a>(
+    directive_ln: &DirectiveLine<'a>,
     mode: TestMode,
 ) -> CheckDirectiveResult<'a> {
+    let &DirectiveLine { raw_directive: directive_ln, .. } = directive_ln;
+
     let (directive_name, post) = directive_ln.split_once([':', ' ']).unwrap_or((directive_ln, ""));
 
     let is_known_directive = KNOWN_DIRECTIVE_NAMES.contains(&directive_name)
@@ -980,7 +966,7 @@ fn iter_directives(
         // Perform unknown directive check on Rust files.
         if testfile.extension() == Some("rs") {
             let CheckDirectiveResult { is_known_directive, trailing_directive } =
-                check_directive(directive_line.raw_directive, mode);
+                check_directive(&directive_line, mode);
 
             if !is_known_directive {
                 *poisoned = true;
@@ -1014,8 +1000,7 @@ impl Config {
     fn parse_and_update_revisions(
         &self,
         testfile: &Utf8Path,
-        line_number: usize,
-        line: &str,
+        line: &DirectiveLine<'_>,
         existing: &mut Vec<String>,
     ) {
         const FORBIDDEN_REVISION_NAMES: [&str; 2] = [
@@ -1028,8 +1013,7 @@ impl Config {
         const FILECHECK_FORBIDDEN_REVISION_NAMES: [&str; 9] =
             ["CHECK", "COM", "NEXT", "SAME", "EMPTY", "NOT", "COUNT", "DAG", "LABEL"];
 
-        if let Some(raw) = self.parse_name_value_directive(line, "revisions", testfile, line_number)
-        {
+        if let Some(raw) = self.parse_name_value_directive(line, "revisions", testfile) {
             if self.mode == TestMode::RunMake {
                 panic!("`run-make` mode tests do not support revisions: {}", testfile);
             }
@@ -1074,13 +1058,8 @@ impl Config {
         (name.to_owned(), value.to_owned())
     }
 
-    fn parse_pp_exact(
-        &self,
-        line: &str,
-        testfile: &Utf8Path,
-        line_number: usize,
-    ) -> Option<Utf8PathBuf> {
-        if let Some(s) = self.parse_name_value_directive(line, "pp-exact", testfile, line_number) {
+    fn parse_pp_exact(&self, line: &DirectiveLine<'_>, testfile: &Utf8Path) -> Option<Utf8PathBuf> {
+        if let Some(s) = self.parse_name_value_directive(line, "pp-exact", testfile) {
             Some(Utf8PathBuf::from(&s))
         } else if self.parse_name_directive(line, "pp-exact") {
             testfile.file_name().map(Utf8PathBuf::from)
@@ -1089,7 +1068,9 @@ impl Config {
         }
     }
 
-    fn parse_custom_normalization(&self, raw_directive: &str) -> Option<NormalizeRule> {
+    fn parse_custom_normalization(&self, line: &DirectiveLine<'_>) -> Option<NormalizeRule> {
+        let &DirectiveLine { raw_directive, .. } = line;
+
         // FIXME(Zalathar): Integrate name/value splitting into `DirectiveLine`
         // instead of doing it here.
         let (directive_name, raw_value) = raw_directive.split_once(':')?;
@@ -1110,24 +1091,23 @@ impl Config {
         Some(NormalizeRule { kind, regex, replacement })
     }
 
-    fn parse_name_directive(&self, line: &str, directive: &str) -> bool {
+    fn parse_name_directive(&self, line: &DirectiveLine<'_>, directive: &str) -> bool {
+        let &DirectiveLine { raw_directive: line, .. } = line;
+
         // Ensure the directive is a whole word. Do not match "ignore-x86" when
         // the line says "ignore-x86_64".
         line.starts_with(directive)
             && matches!(line.as_bytes().get(directive.len()), None | Some(&b' ') | Some(&b':'))
     }
 
-    fn parse_negative_name_directive(&self, line: &str, directive: &str) -> bool {
-        line.starts_with("no-") && self.parse_name_directive(&line[3..], directive)
-    }
-
-    pub fn parse_name_value_directive(
+    fn parse_name_value_directive(
         &self,
-        line: &str,
+        line: &DirectiveLine<'_>,
         directive: &str,
         testfile: &Utf8Path,
-        line_number: usize,
     ) -> Option<String> {
+        let &DirectiveLine { line_number, raw_directive: line, .. } = line;
+
         let colon = directive.len();
         if line.starts_with(directive) && line.as_bytes().get(colon) == Some(&b':') {
             let value = line[(colon + 1)..].to_owned();
@@ -1144,52 +1124,37 @@ impl Config {
         }
     }
 
-    fn parse_edition(&self, line: &str, testfile: &Utf8Path, line_number: usize) -> Option<String> {
-        self.parse_name_value_directive(line, "edition", testfile, line_number)
+    fn parse_edition(&self, line: &DirectiveLine<'_>, testfile: &Utf8Path) -> Option<String> {
+        self.parse_name_value_directive(line, "edition", testfile)
     }
 
-    fn set_name_directive(&self, line: &str, directive: &str, value: &mut bool) {
-        match value {
-            true => {
-                if self.parse_negative_name_directive(line, directive) {
-                    *value = false;
-                }
-            }
-            false => {
-                if self.parse_name_directive(line, directive) {
-                    *value = true;
-                }
-            }
-        }
+    fn set_name_directive(&self, line: &DirectiveLine<'_>, directive: &str, value: &mut bool) {
+        // If the flag is already true, don't bother looking at the directive.
+        *value = *value || self.parse_name_directive(line, directive);
     }
 
     fn set_name_value_directive<T>(
         &self,
-        line: &str,
+        line: &DirectiveLine<'_>,
         directive: &str,
         testfile: &Utf8Path,
-        line_number: usize,
         value: &mut Option<T>,
         parse: impl FnOnce(String) -> T,
     ) {
         if value.is_none() {
-            *value =
-                self.parse_name_value_directive(line, directive, testfile, line_number).map(parse);
+            *value = self.parse_name_value_directive(line, directive, testfile).map(parse);
         }
     }
 
     fn push_name_value_directive<T>(
         &self,
-        line: &str,
+        line: &DirectiveLine<'_>,
         directive: &str,
         testfile: &Utf8Path,
-        line_number: usize,
         values: &mut Vec<T>,
         parse: impl FnOnce(String) -> T,
     ) {
-        if let Some(value) =
-            self.parse_name_value_directive(line, directive, testfile, line_number).map(parse)
-        {
+        if let Some(value) = self.parse_name_value_directive(line, directive, testfile).map(parse) {
             values.push(value);
         }
     }
@@ -1482,8 +1447,8 @@ pub(crate) fn make_test_description<R: Read>(
         &mut local_poisoned,
         path,
         src,
-        &mut |directive @ DirectiveLine { line_number, raw_directive: ln, .. }| {
-            if !directive.applies_to_test_revision(test_revision) {
+        &mut |ref ln @ DirectiveLine { line_number, .. }| {
+            if !ln.applies_to_test_revision(test_revision) {
                 return;
             }
 
@@ -1507,9 +1472,9 @@ pub(crate) fn make_test_description<R: Read>(
             decision!(cfg::handle_ignore(config, ln));
             decision!(cfg::handle_only(config, ln));
             decision!(needs::handle_needs(&cache.needs, config, ln));
-            decision!(ignore_llvm(config, path, ln, line_number));
-            decision!(ignore_backends(config, path, ln, line_number));
-            decision!(needs_backends(config, path, ln, line_number));
+            decision!(ignore_llvm(config, path, ln));
+            decision!(ignore_backends(config, path, ln));
+            decision!(needs_backends(config, path, ln));
             decision!(ignore_cdb(config, ln));
             decision!(ignore_gdb(config, ln));
             decision!(ignore_lldb(config, ln));
@@ -1549,7 +1514,9 @@ pub(crate) fn make_test_description<R: Read>(
     }
 }
 
-fn ignore_cdb(config: &Config, line: &str) -> IgnoreDecision {
+fn ignore_cdb(config: &Config, line: &DirectiveLine<'_>) -> IgnoreDecision {
+    let &DirectiveLine { raw_directive: line, .. } = line;
+
     if config.debugger != Some(Debugger::Cdb) {
         return IgnoreDecision::Continue;
     }
@@ -1572,7 +1539,9 @@ fn ignore_cdb(config: &Config, line: &str) -> IgnoreDecision {
     IgnoreDecision::Continue
 }
 
-fn ignore_gdb(config: &Config, line: &str) -> IgnoreDecision {
+fn ignore_gdb(config: &Config, line: &DirectiveLine<'_>) -> IgnoreDecision {
+    let &DirectiveLine { raw_directive: line, .. } = line;
+
     if config.debugger != Some(Debugger::Gdb) {
         return IgnoreDecision::Continue;
     }
@@ -1620,7 +1589,9 @@ fn ignore_gdb(config: &Config, line: &str) -> IgnoreDecision {
     IgnoreDecision::Continue
 }
 
-fn ignore_lldb(config: &Config, line: &str) -> IgnoreDecision {
+fn ignore_lldb(config: &Config, line: &DirectiveLine<'_>) -> IgnoreDecision {
+    let &DirectiveLine { raw_directive: line, .. } = line;
+
     if config.debugger != Some(Debugger::Lldb) {
         return IgnoreDecision::Continue;
     }
@@ -1642,14 +1613,9 @@ fn ignore_lldb(config: &Config, line: &str) -> IgnoreDecision {
     IgnoreDecision::Continue
 }
 
-fn ignore_backends(
-    config: &Config,
-    path: &Utf8Path,
-    line: &str,
-    line_number: usize,
-) -> IgnoreDecision {
+fn ignore_backends(config: &Config, path: &Utf8Path, line: &DirectiveLine<'_>) -> IgnoreDecision {
     if let Some(backends_to_ignore) =
-        config.parse_name_value_directive(line, "ignore-backends", path, line_number)
+        config.parse_name_value_directive(line, "ignore-backends", path)
     {
         for backend in backends_to_ignore.split_whitespace().map(|backend| {
             match CodegenBackend::try_from(backend) {
@@ -1669,15 +1635,8 @@ fn ignore_backends(
     IgnoreDecision::Continue
 }
 
-fn needs_backends(
-    config: &Config,
-    path: &Utf8Path,
-    line: &str,
-    line_number: usize,
-) -> IgnoreDecision {
-    if let Some(needed_backends) =
-        config.parse_name_value_directive(line, "needs-backends", path, line_number)
-    {
+fn needs_backends(config: &Config, path: &Utf8Path, line: &DirectiveLine<'_>) -> IgnoreDecision {
+    if let Some(needed_backends) = config.parse_name_value_directive(line, "needs-backends", path) {
         if !needed_backends
             .split_whitespace()
             .map(|backend| match CodegenBackend::try_from(backend) {
@@ -1699,9 +1658,9 @@ fn needs_backends(
     IgnoreDecision::Continue
 }
 
-fn ignore_llvm(config: &Config, path: &Utf8Path, line: &str, line_number: usize) -> IgnoreDecision {
+fn ignore_llvm(config: &Config, path: &Utf8Path, line: &DirectiveLine<'_>) -> IgnoreDecision {
     if let Some(needed_components) =
-        config.parse_name_value_directive(line, "needs-llvm-components", path, line_number)
+        config.parse_name_value_directive(line, "needs-llvm-components", path)
     {
         let components: HashSet<_> = config.llvm_components.split_whitespace().collect();
         if let Some(missing_component) = needed_components
@@ -1723,7 +1682,7 @@ fn ignore_llvm(config: &Config, path: &Utf8Path, line: &str, line_number: usize)
         // Note that these `min` versions will check for not just major versions.
 
         if let Some(version_string) =
-            config.parse_name_value_directive(line, "min-llvm-version", path, line_number)
+            config.parse_name_value_directive(line, "min-llvm-version", path)
         {
             let min_version = extract_llvm_version(&version_string);
             // Ignore if actual version is smaller than the minimum required version.
@@ -1735,7 +1694,7 @@ fn ignore_llvm(config: &Config, path: &Utf8Path, line: &str, line_number: usize)
                 };
             }
         } else if let Some(version_string) =
-            config.parse_name_value_directive(line, "max-llvm-major-version", path, line_number)
+            config.parse_name_value_directive(line, "max-llvm-major-version", path)
         {
             let max_version = extract_llvm_version(&version_string);
             // Ignore if actual major version is larger than the maximum required major version.
@@ -1749,7 +1708,7 @@ fn ignore_llvm(config: &Config, path: &Utf8Path, line: &str, line_number: usize)
                 };
             }
         } else if let Some(version_string) =
-            config.parse_name_value_directive(line, "min-system-llvm-version", path, line_number)
+            config.parse_name_value_directive(line, "min-system-llvm-version", path)
         {
             let min_version = extract_llvm_version(&version_string);
             // Ignore if using system LLVM and actual version
@@ -1762,7 +1721,7 @@ fn ignore_llvm(config: &Config, path: &Utf8Path, line: &str, line_number: usize)
                 };
             }
         } else if let Some(version_range) =
-            config.parse_name_value_directive(line, "ignore-llvm-version", path, line_number)
+            config.parse_name_value_directive(line, "ignore-llvm-version", path)
         {
             // Syntax is: "ignore-llvm-version: <version1> [- <version2>]"
             let (v_min, v_max) =
@@ -1788,7 +1747,7 @@ fn ignore_llvm(config: &Config, path: &Utf8Path, line: &str, line_number: usize)
                 }
             }
         } else if let Some(version_string) =
-            config.parse_name_value_directive(line, "exact-llvm-major-version", path, line_number)
+            config.parse_name_value_directive(line, "exact-llvm-major-version", path)
         {
             // Syntax is "exact-llvm-major-version: <version>"
             let version = extract_llvm_version(&version_string);
diff --git a/src/tools/compiletest/src/directives/auxiliary.rs b/src/tools/compiletest/src/directives/auxiliary.rs
index 7c1ed2e7006..0675a6feac3 100644
--- a/src/tools/compiletest/src/directives/auxiliary.rs
+++ b/src/tools/compiletest/src/directives/auxiliary.rs
@@ -7,6 +7,7 @@ use camino::Utf8Path;
 
 use super::directives::{AUX_BIN, AUX_BUILD, AUX_CODEGEN_BACKEND, AUX_CRATE, PROC_MACRO};
 use crate::common::Config;
+use crate::directives::DirectiveLine;
 
 /// Properties parsed from `aux-*` test directives.
 #[derive(Clone, Debug, Default)]
@@ -45,40 +46,28 @@ impl AuxProps {
 /// and update [`AuxProps`] accordingly.
 pub(super) fn parse_and_update_aux(
     config: &Config,
-    ln: &str,
+    directive_line: &DirectiveLine<'_>,
     testfile: &Utf8Path,
-    line_number: usize,
     aux: &mut AuxProps,
 ) {
+    let &DirectiveLine { raw_directive: ln, .. } = directive_line;
+
     if !(ln.starts_with("aux-") || ln.starts_with("proc-macro")) {
         return;
     }
 
-    config.push_name_value_directive(ln, AUX_BUILD, testfile, line_number, &mut aux.builds, |r| {
+    let ln = directive_line;
+
+    config.push_name_value_directive(ln, AUX_BUILD, testfile, &mut aux.builds, |r| {
         r.trim().to_string()
     });
-    config.push_name_value_directive(ln, AUX_BIN, testfile, line_number, &mut aux.bins, |r| {
+    config
+        .push_name_value_directive(ln, AUX_BIN, testfile, &mut aux.bins, |r| r.trim().to_string());
+    config.push_name_value_directive(ln, AUX_CRATE, testfile, &mut aux.crates, parse_aux_crate);
+    config.push_name_value_directive(ln, PROC_MACRO, testfile, &mut aux.proc_macros, |r| {
         r.trim().to_string()
     });
-    config.push_name_value_directive(
-        ln,
-        AUX_CRATE,
-        testfile,
-        line_number,
-        &mut aux.crates,
-        parse_aux_crate,
-    );
-    config.push_name_value_directive(
-        ln,
-        PROC_MACRO,
-        testfile,
-        line_number,
-        &mut aux.proc_macros,
-        |r| r.trim().to_string(),
-    );
-    if let Some(r) =
-        config.parse_name_value_directive(ln, AUX_CODEGEN_BACKEND, testfile, line_number)
-    {
+    if let Some(r) = config.parse_name_value_directive(ln, AUX_CODEGEN_BACKEND, testfile) {
         aux.codegen_backend = Some(r.trim().to_owned());
     }
 }
diff --git a/src/tools/compiletest/src/directives/cfg.rs b/src/tools/compiletest/src/directives/cfg.rs
index 802a1d63d1f..62a4b88a33a 100644
--- a/src/tools/compiletest/src/directives/cfg.rs
+++ b/src/tools/compiletest/src/directives/cfg.rs
@@ -1,12 +1,14 @@
 use std::collections::HashSet;
 
 use crate::common::{CompareMode, Config, Debugger};
-use crate::directives::IgnoreDecision;
+use crate::directives::{DirectiveLine, IgnoreDecision};
 
 const EXTRA_ARCHS: &[&str] = &["spirv"];
 
-pub(super) fn handle_ignore(config: &Config, line: &str) -> IgnoreDecision {
+pub(super) fn handle_ignore(config: &Config, line: &DirectiveLine<'_>) -> IgnoreDecision {
     let parsed = parse_cfg_name_directive(config, line, "ignore");
+    let &DirectiveLine { raw_directive: line, .. } = line;
+
     match parsed.outcome {
         MatchOutcome::NoMatch => IgnoreDecision::Continue,
         MatchOutcome::Match => IgnoreDecision::Ignore {
@@ -21,8 +23,10 @@ pub(super) fn handle_ignore(config: &Config, line: &str) -> IgnoreDecision {
     }
 }
 
-pub(super) fn handle_only(config: &Config, line: &str) -> IgnoreDecision {
+pub(super) fn handle_only(config: &Config, line: &DirectiveLine<'_>) -> IgnoreDecision {
     let parsed = parse_cfg_name_directive(config, line, "only");
+    let &DirectiveLine { raw_directive: line, .. } = line;
+
     match parsed.outcome {
         MatchOutcome::Match => IgnoreDecision::Continue,
         MatchOutcome::NoMatch => IgnoreDecision::Ignore {
@@ -43,9 +47,11 @@ pub(super) fn handle_only(config: &Config, line: &str) -> IgnoreDecision {
 /// or `only-windows`.
 fn parse_cfg_name_directive<'a>(
     config: &Config,
-    line: &'a str,
+    line: &'a DirectiveLine<'a>,
     prefix: &str,
 ) -> ParsedNameDirective<'a> {
+    let &DirectiveLine { raw_directive: line, .. } = line;
+
     if !line.as_bytes().starts_with(prefix.as_bytes()) {
         return ParsedNameDirective::not_a_directive();
     }
diff --git a/src/tools/compiletest/src/directives/needs.rs b/src/tools/compiletest/src/directives/needs.rs
index 3b7a9478717..c8a729d8aab 100644
--- a/src/tools/compiletest/src/directives/needs.rs
+++ b/src/tools/compiletest/src/directives/needs.rs
@@ -1,10 +1,10 @@
 use crate::common::{Config, KNOWN_CRATE_TYPES, KNOWN_TARGET_HAS_ATOMIC_WIDTHS, Sanitizer};
-use crate::directives::{IgnoreDecision, llvm_has_libzstd};
+use crate::directives::{DirectiveLine, IgnoreDecision, llvm_has_libzstd};
 
 pub(super) fn handle_needs(
     cache: &CachedNeedsConditions,
     config: &Config,
-    ln: &str,
+    ln: &DirectiveLine<'_>,
 ) -> IgnoreDecision {
     // Note that we intentionally still put the needs- prefix here to make the file show up when
     // grepping for a directive name, even though we could technically strip that.
@@ -181,6 +181,8 @@ pub(super) fn handle_needs(
         },
     ];
 
+    let &DirectiveLine { raw_directive: ln, .. } = ln;
+
     let (name, rest) = match ln.split_once([':', ' ']) {
         Some((name, rest)) => (name, Some(rest)),
         None => (ln, None),
diff --git a/src/tools/compiletest/src/runtest/debugger.rs b/src/tools/compiletest/src/runtest/debugger.rs
index ba824124e87..3d439e98eb7 100644
--- a/src/tools/compiletest/src/runtest/debugger.rs
+++ b/src/tools/compiletest/src/runtest/debugger.rs
@@ -4,7 +4,6 @@ use std::io::{BufRead, BufReader};
 
 use camino::{Utf8Path, Utf8PathBuf};
 
-use crate::common::Config;
 use crate::runtest::ProcRes;
 
 /// Representation of information to invoke a debugger and check its output
@@ -20,11 +19,7 @@ pub(super) struct DebuggerCommands {
 }
 
 impl DebuggerCommands {
-    pub fn parse_from(
-        file: &Utf8Path,
-        config: &Config,
-        debugger_prefix: &str,
-    ) -> Result<Self, String> {
+    pub fn parse_from(file: &Utf8Path, debugger_prefix: &str) -> Result<Self, String> {
         let command_directive = format!("{debugger_prefix}-command");
         let check_directive = format!("{debugger_prefix}-check");
 
@@ -47,14 +42,10 @@ impl DebuggerCommands {
                 continue;
             };
 
-            if let Some(command) =
-                config.parse_name_value_directive(&line, &command_directive, file, line_no)
-            {
+            if let Some(command) = parse_name_value(&line, &command_directive) {
                 commands.push(command);
             }
-            if let Some(pattern) =
-                config.parse_name_value_directive(&line, &check_directive, file, line_no)
-            {
+            if let Some(pattern) = parse_name_value(&line, &check_directive) {
                 check_lines.push((line_no, pattern));
             }
         }
@@ -114,6 +105,18 @@ impl DebuggerCommands {
     }
 }
 
+/// Split off from the main `parse_name_value_directive`, so that improvements
+/// to directive handling aren't held back by debuginfo test commands.
+fn parse_name_value(line: &str, name: &str) -> Option<String> {
+    if let Some(after_name) = line.strip_prefix(name)
+        && let Some(value) = after_name.strip_prefix(':')
+    {
+        Some(value.to_owned())
+    } else {
+        None
+    }
+}
+
 /// Check that the pattern in `check_line` applies to `line`. Returns `true` if they do match.
 fn check_single_line(line: &str, check_line: &str) -> bool {
     // Allow check lines to leave parts unspecified (e.g., uninitialized
diff --git a/src/tools/compiletest/src/runtest/debuginfo.rs b/src/tools/compiletest/src/runtest/debuginfo.rs
index 071c0863b7e..9175a38ffa5 100644
--- a/src/tools/compiletest/src/runtest/debuginfo.rs
+++ b/src/tools/compiletest/src/runtest/debuginfo.rs
@@ -59,7 +59,7 @@ impl TestCx<'_> {
         }
 
         // Parse debugger commands etc from test files
-        let dbg_cmds = DebuggerCommands::parse_from(&self.testpaths.file, self.config, "cdb")
+        let dbg_cmds = DebuggerCommands::parse_from(&self.testpaths.file, "cdb")
             .unwrap_or_else(|e| self.fatal(&e));
 
         // https://docs.microsoft.com/en-us/windows-hardware/drivers/debugger/debugger-commands
@@ -130,7 +130,7 @@ impl TestCx<'_> {
     }
 
     fn run_debuginfo_gdb_test_no_opt(&self) {
-        let dbg_cmds = DebuggerCommands::parse_from(&self.testpaths.file, self.config, "gdb")
+        let dbg_cmds = DebuggerCommands::parse_from(&self.testpaths.file, "gdb")
             .unwrap_or_else(|e| self.fatal(&e));
         let mut cmds = dbg_cmds.commands.join("\n");
 
@@ -397,7 +397,7 @@ impl TestCx<'_> {
         }
 
         // Parse debugger commands etc from test files
-        let dbg_cmds = DebuggerCommands::parse_from(&self.testpaths.file, self.config, "lldb")
+        let dbg_cmds = DebuggerCommands::parse_from(&self.testpaths.file, "lldb")
             .unwrap_or_else(|e| self.fatal(&e));
 
         // Write debugger script:
diff --git a/src/tools/miri/tests/pass/static_align.rs b/src/tools/miri/tests/pass/static_align.rs
index f292f028568..bc6a9bf8af7 100644
--- a/src/tools/miri/tests/pass/static_align.rs
+++ b/src/tools/miri/tests/pass/static_align.rs
@@ -1,4 +1,7 @@
 #![feature(static_align)]
+#![deny(non_upper_case_globals)]
+
+use std::cell::Cell;
 
 // When a static uses `align(N)`, its address should be a multiple of `N`.
 
@@ -8,7 +11,64 @@ static FOO: u64 = 0;
 #[rustc_align_static(512)]
 static BAR: u64 = 0;
 
+struct HasDrop(*const HasDrop);
+
+impl Drop for HasDrop {
+    fn drop(&mut self) {
+        assert_eq!(core::ptr::from_mut(self).cast_const(), self.0);
+    }
+}
+
+thread_local! {
+    #[rustc_align_static(4096)]
+    static LOCAL: u64 = 0;
+
+    #[allow(unused_mut, reason = "test attribute handling")]
+    #[cfg_attr(true, rustc_align_static(4096))]
+    static CONST_LOCAL: u64 = const { 0 };
+
+    #[cfg_attr(any(true), cfg_attr(true, rustc_align_static(4096)))]
+    #[allow(unused_mut, reason = "test attribute handling")]
+    static HASDROP_LOCAL: Cell<HasDrop> = Cell::new(HasDrop(core::ptr::null()));
+
+    /// I love doc comments.
+    #[allow(unused_mut, reason = "test attribute handling")]
+    #[cfg_attr(all(),
+      cfg_attr(any(true),
+      cfg_attr(true, rustc_align_static(4096))))]
+    #[allow(unused_mut, reason = "test attribute handling")]
+    /// I love doc comments.
+    static HASDROP_CONST_LOCAL: Cell<HasDrop> = const { Cell::new(HasDrop(core::ptr::null())) };
+
+    #[cfg_attr(true,)]
+    #[cfg_attr(false,)]
+    #[cfg_attr(
+        true,
+        rustc_align_static(32),
+        cfg_attr(true, allow(non_upper_case_globals, reason = "test attribute handling")),
+        cfg_attr(false,)
+    )]
+    #[cfg_attr(false, rustc_align_static(0))]
+    static more_attr_testing: u64 = 0;
+}
+
+fn thread_local_ptr<T>(key: &'static std::thread::LocalKey<T>) -> *const T {
+    key.with(|local| core::ptr::from_ref::<T>(local))
+}
+
 fn main() {
     assert!(core::ptr::from_ref(&FOO).addr().is_multiple_of(256));
     assert!(core::ptr::from_ref(&BAR).addr().is_multiple_of(512));
+
+    assert!(thread_local_ptr(&LOCAL).addr().is_multiple_of(4096));
+    assert!(thread_local_ptr(&CONST_LOCAL).addr().is_multiple_of(4096));
+    assert!(thread_local_ptr(&HASDROP_LOCAL).addr().is_multiple_of(4096));
+    assert!(thread_local_ptr(&HASDROP_CONST_LOCAL).addr().is_multiple_of(4096));
+    assert!(thread_local_ptr(&more_attr_testing).addr().is_multiple_of(32));
+
+    // Test that address (and therefore alignment) is maintained during drop
+    let hasdrop_ptr = thread_local_ptr(&HASDROP_LOCAL);
+    core::mem::forget(HASDROP_LOCAL.replace(HasDrop(hasdrop_ptr.cast())));
+    let hasdrop_const_ptr = thread_local_ptr(&HASDROP_CONST_LOCAL);
+    core::mem::forget(HASDROP_CONST_LOCAL.replace(HasDrop(hasdrop_const_ptr.cast())));
 }
diff --git a/src/tools/miri/tests/pass/thread_local-panic.rs b/src/tools/miri/tests/pass/thread_local-panic.rs
new file mode 100644
index 00000000000..549acd23987
--- /dev/null
+++ b/src/tools/miri/tests/pass/thread_local-panic.rs
@@ -0,0 +1,8 @@
+thread_local! {
+    static LOCAL: u64 = panic!();
+
+}
+
+fn main() {
+    let _ = std::panic::catch_unwind(|| LOCAL.with(|_| {}));
+}
diff --git a/src/tools/miri/tests/pass/thread_local-panic.stderr b/src/tools/miri/tests/pass/thread_local-panic.stderr
new file mode 100644
index 00000000000..e69340a8102
--- /dev/null
+++ b/src/tools/miri/tests/pass/thread_local-panic.stderr
@@ -0,0 +1,5 @@
+
+thread 'main' ($TID) panicked at tests/pass/thread_local-panic.rs:LL:CC:
+explicit panic
+note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+note: in Miri, you may have to set `MIRIFLAGS=-Zmiri-env-forward=RUST_BACKTRACE` for the environment variable to have an effect
diff --git a/src/tools/rust-analyzer/.github/workflows/ci.yaml b/src/tools/rust-analyzer/.github/workflows/ci.yaml
index 770652494f4..0eb57a605f8 100644
--- a/src/tools/rust-analyzer/.github/workflows/ci.yaml
+++ b/src/tools/rust-analyzer/.github/workflows/ci.yaml
@@ -56,8 +56,8 @@ jobs:
       # Install a pinned rustc commit to avoid surprises
       - name: Install Rust toolchain
         run: |
-          RUSTC_VERSION=`cat rust-version`
-          rustup-toolchain-install-master ${RUSTC_VERSION} -c rust-src -c rustfmt
+          RUSTC_VERSION=$(cat rust-version)
+          rustup-toolchain-install-master ${RUSTC_VERSION} -c cargo -c rust-src -c rustfmt
           rustup default ${RUSTC_VERSION}
 
       # Emulate a nightly toolchain, because the toolchain installed above does not have "nightly"
@@ -98,9 +98,9 @@ jobs:
         run: |
           rustup update --no-self-update stable
           rustup default stable
-          rustup component add --toolchain stable rust-src clippy
-          # We always use a nightly rustfmt, regardless of channel, because we need
-          # --file-lines.
+          rustup component add --toolchain stable rust-src clippy rustfmt
+          # We also install a nightly rustfmt, because we use `--file-lines` in
+          # a test.
           rustup toolchain install nightly --profile minimal --component rustfmt
       # https://github.com/actions-rust-lang/setup-rust-toolchain/blob/main/rust.json
       - name: Install Rust Problem Matcher
diff --git a/src/tools/rust-analyzer/Cargo.lock b/src/tools/rust-analyzer/Cargo.lock
index 17dea1ba4cd..086f38f06a5 100644
--- a/src/tools/rust-analyzer/Cargo.lock
+++ b/src/tools/rust-analyzer/Cargo.lock
@@ -546,6 +546,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "fixedbitset"
+version = "0.5.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1d674e81391d1e1ab681a28d99df07927c6d4aa5b027d7da16ba32d1d21ecd99"
+
+[[package]]
 name = "flate2"
 version = "1.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -775,6 +781,7 @@ dependencies = [
  "itertools",
  "la-arena 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "oorandom",
+ "petgraph",
  "project-model",
  "query-group-macro",
  "ra-ap-rustc_abi",
@@ -1327,9 +1334,9 @@ dependencies = [
 
 [[package]]
 name = "memchr"
-version = "2.7.5"
+version = "2.7.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "32a282da65faaf38286cf3be983213fcf1d2e2a58700e808f83f4ea9a4804bc0"
+checksum = "f52b00d39961fc5b2736ea853c9cc86238e165017a493d1d5c8eac6bdc4cc273"
 
 [[package]]
 name = "memmap2"
@@ -1595,6 +1602,17 @@ dependencies = [
 ]
 
 [[package]]
+name = "petgraph"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "54acf3a685220b533e437e264e4d932cfbdc4cc7ec0cd232ed73c08d03b8a7ca"
+dependencies = [
+ "fixedbitset",
+ "hashbrown 0.15.4",
+ "indexmap",
+]
+
+[[package]]
 name = "pin-project-lite"
 version = "0.2.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
diff --git a/src/tools/rust-analyzer/Cargo.toml b/src/tools/rust-analyzer/Cargo.toml
index 0401367f786..d3a4e375613 100644
--- a/src/tools/rust-analyzer/Cargo.toml
+++ b/src/tools/rust-analyzer/Cargo.toml
@@ -170,6 +170,7 @@ tracing-subscriber = { version = "0.3.20", default-features = false, features =
 triomphe = { version = "0.1.14", default-features = false, features = ["std"] }
 url = "2.5.4"
 xshell = "0.2.7"
+petgraph = { version = "0.8.2", default-features = false }
 
 # We need to freeze the version of the crate, as the raw-api feature is considered unstable
 dashmap = { version = "=6.1.0", features = ["raw-api", "inline"] }
diff --git a/src/tools/rust-analyzer/crates/hir-ty/Cargo.toml b/src/tools/rust-analyzer/crates/hir-ty/Cargo.toml
index 138d02e5a61..4013d19ad08 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/Cargo.toml
+++ b/src/tools/rust-analyzer/crates/hir-ty/Cargo.toml
@@ -34,6 +34,7 @@ rustc_apfloat = "0.2.3"
 query-group.workspace = true
 salsa.workspace = true
 salsa-macros.workspace = true
+petgraph.workspace = true
 
 ra-ap-rustc_abi.workspace = true
 ra-ap-rustc_index.workspace = true
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/autoderef.rs b/src/tools/rust-analyzer/crates/hir-ty/src/autoderef.rs
index fd60ffcf24b..21a86d3e437 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/autoderef.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/autoderef.rs
@@ -32,11 +32,11 @@ const AUTODEREF_RECURSION_LIMIT: usize = 20;
 /// - the yielded types don't contain inference variables (but may contain `TyKind::Error`).
 /// - a type won't be yielded more than once; in other words, the returned iterator will stop if it
 ///   detects a cycle in the deref chain.
-pub fn autoderef(
-    db: &dyn HirDatabase,
-    env: Arc<TraitEnvironment>,
+pub fn autoderef<'db>(
+    db: &'db dyn HirDatabase,
+    env: Arc<TraitEnvironment<'db>>,
     ty: crate::Canonical<crate::Ty>,
-) -> impl Iterator<Item = crate::Ty> {
+) -> impl Iterator<Item = crate::Ty> + use<> {
     let mut table = InferenceTable::new(db, env);
     let interner = table.interner;
     let ty = table.instantiate_canonical(ty);
@@ -298,7 +298,7 @@ fn structurally_normalize_ty<'db>(
 ) -> Option<(Ty<'db>, PredicateObligations<'db>)> {
     let mut ocx = ObligationCtxt::new(&table.infer_ctxt);
     let Ok(normalized_ty) =
-        ocx.structurally_normalize_ty(&ObligationCause::misc(), table.param_env, ty)
+        ocx.structurally_normalize_ty(&ObligationCause::misc(), table.trait_env.env, ty)
     else {
         // We shouldn't have errors here in the old solver, except for
         // evaluate/fulfill mismatches, but that's not a reason for an ICE.
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/builder.rs b/src/tools/rust-analyzer/crates/hir-ty/src/builder.rs
index 3755175cf51..5511587c71a 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/builder.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/builder.rs
@@ -3,17 +3,20 @@
 use chalk_ir::{
     AdtId, DebruijnIndex, Scalar,
     cast::{Cast, CastTo, Caster},
-    fold::TypeFoldable,
-    interner::HasInterner,
 };
 use hir_def::{GenericDefId, GenericParamId, TraitId, TypeAliasId, builtin_type::BuiltinType};
 use smallvec::SmallVec;
 
 use crate::{
-    Binders, BoundVar, CallableSig, GenericArg, GenericArgData, Interner, ProjectionTy,
-    Substitution, TraitRef, Ty, TyDefId, TyExt, TyKind, consteval::unknown_const_as_generic,
-    db::HirDatabase, error_lifetime, generics::generics, infer::unify::InferenceTable, primitive,
-    to_assoc_type_id, to_chalk_trait_id,
+    BoundVar, CallableSig, GenericArg, GenericArgData, Interner, ProjectionTy, Substitution,
+    TraitRef, Ty, TyDefId, TyExt, TyKind,
+    consteval::unknown_const_as_generic,
+    db::HirDatabase,
+    error_lifetime,
+    generics::generics,
+    infer::unify::InferenceTable,
+    next_solver::{DbInterner, EarlyBinder, mapping::ChalkToNextSolver},
+    primitive, to_assoc_type_id, to_chalk_trait_id,
 };
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -345,19 +348,20 @@ impl TyBuilder<TypeAliasId> {
     }
 }
 
-impl<T: HasInterner<Interner = Interner> + TypeFoldable<Interner>> TyBuilder<Binders<T>> {
-    pub fn build(self) -> T {
+impl<'db, T: rustc_type_ir::TypeFoldable<DbInterner<'db>>> TyBuilder<EarlyBinder<'db, T>> {
+    pub fn build(self, interner: DbInterner<'db>) -> T {
         let (b, subst) = self.build_internal();
-        b.substitute(Interner, &subst)
+        let args: crate::next_solver::GenericArgs<'db> = subst.to_nextsolver(interner);
+        b.instantiate(interner, args)
     }
 }
 
-impl TyBuilder<Binders<Ty>> {
+impl<'db> TyBuilder<EarlyBinder<'db, crate::next_solver::Ty<'db>>> {
     pub fn def_ty(
-        db: &dyn HirDatabase,
+        db: &'db dyn HirDatabase,
         def: TyDefId,
         parent_subst: Option<Substitution>,
-    ) -> TyBuilder<Binders<Ty>> {
+    ) -> TyBuilder<EarlyBinder<'db, crate::next_solver::Ty<'db>>> {
         let poly_ty = db.ty(def);
         let id: GenericDefId = match def {
             TyDefId::BuiltinType(_) => {
@@ -370,7 +374,10 @@ impl TyBuilder<Binders<Ty>> {
         TyBuilder::subst_for_def(db, id, parent_subst).with_data(poly_ty)
     }
 
-    pub fn impl_self_ty(db: &dyn HirDatabase, def: hir_def::ImplId) -> TyBuilder<Binders<Ty>> {
+    pub fn impl_self_ty(
+        db: &'db dyn HirDatabase,
+        def: hir_def::ImplId,
+    ) -> TyBuilder<EarlyBinder<'db, crate::next_solver::Ty<'db>>> {
         TyBuilder::subst_for_def(db, def, None).with_data(db.impl_self_ty(def))
     }
 }
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/chalk_ext.rs b/src/tools/rust-analyzer/crates/hir-ty/src/chalk_ext.rs
index 1faf9f66dc5..6956a0a1232 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/chalk_ext.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/chalk_ext.rs
@@ -15,8 +15,13 @@ use crate::{
     AdtId, AliasEq, AliasTy, Binders, CallableDefId, CallableSig, Canonical, CanonicalVarKinds,
     ClosureId, DynTy, FnPointer, ImplTraitId, InEnvironment, Interner, Lifetime, ProjectionTy,
     QuantifiedWhereClause, Substitution, ToChalk, TraitRef, Ty, TyBuilder, TyKind, TypeFlags,
-    WhereClause, db::HirDatabase, from_assoc_type_id, from_chalk_trait_id, from_foreign_def_id,
-    from_placeholder_idx, generics::generics, to_chalk_trait_id, utils::ClosureSubst,
+    WhereClause,
+    db::HirDatabase,
+    from_assoc_type_id, from_chalk_trait_id, from_foreign_def_id, from_placeholder_idx,
+    generics::generics,
+    next_solver::{DbInterner, mapping::NextSolverToChalk},
+    to_chalk_trait_id,
+    utils::ClosureSubst,
 };
 
 pub trait TyExt {
@@ -372,7 +377,10 @@ impl TyExt for Ty {
         let trait_ref = TyBuilder::trait_ref(db, copy_trait).push(self).build();
         let env = db.trait_environment_for_body(owner);
         let goal = Canonical {
-            value: InEnvironment::new(&env.env, trait_ref.cast(Interner)),
+            value: InEnvironment::new(
+                &env.env.to_chalk(DbInterner::new_with(db, Some(env.krate), env.block)),
+                trait_ref.cast(Interner),
+            ),
             binders: CanonicalVarKinds::empty(Interner),
         };
         !db.trait_solve(crate_id, None, goal).no_solution()
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/consteval.rs b/src/tools/rust-analyzer/crates/hir-ty/src/consteval.rs
index 0f2cc17f563..b2daed425ef 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/consteval.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/consteval.rs
@@ -229,7 +229,7 @@ pub(crate) fn const_eval_cycle_result(
     _: &dyn HirDatabase,
     _: GeneralConstId,
     _: Substitution,
-    _: Option<Arc<TraitEnvironment>>,
+    _: Option<Arc<TraitEnvironment<'_>>>,
 ) -> Result<Const, ConstEvalError> {
     Err(ConstEvalError::MirLowerError(MirLowerError::Loop))
 }
@@ -252,7 +252,7 @@ pub(crate) fn const_eval_query(
     db: &dyn HirDatabase,
     def: GeneralConstId,
     subst: Substitution,
-    trait_env: Option<Arc<TraitEnvironment>>,
+    trait_env: Option<Arc<TraitEnvironment<'_>>>,
 ) -> Result<Const, ConstEvalError> {
     let body = match def {
         GeneralConstId::ConstId(c) => {
@@ -327,7 +327,7 @@ pub(crate) fn eval_to_const(
     debruijn: DebruijnIndex,
 ) -> Const {
     let db = ctx.db;
-    let infer = ctx.clone().resolve_all();
+    let infer = ctx.fixme_resolve_all_clone();
     fn has_closure(body: &Body, expr: ExprId) -> bool {
         if matches!(body[expr], Expr::Closure { .. }) {
             return true;
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/consteval/tests.rs b/src/tools/rust-analyzer/crates/hir-ty/src/consteval/tests.rs
index 299b73a7d6c..1586846bbe5 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/consteval/tests.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/consteval/tests.rs
@@ -36,12 +36,12 @@ fn check_fail(
     error: impl FnOnce(ConstEvalError) -> bool,
 ) {
     let (db, file_id) = TestDB::with_single_file(ra_fixture);
-    match eval_goal(&db, file_id) {
+    salsa::attach(&db, || match eval_goal(&db, file_id) {
         Ok(_) => panic!("Expected fail, but it succeeded"),
         Err(e) => {
-            assert!(error(simplify(e.clone())), "Actual error was: {}", pretty_print_err(e, db))
+            assert!(error(simplify(e.clone())), "Actual error was: {}", pretty_print_err(e, &db))
         }
-    }
+    })
 }
 
 #[track_caller]
@@ -79,36 +79,38 @@ fn check_answer(
     check: impl FnOnce(&[u8], &MemoryMap<'_>),
 ) {
     let (db, file_ids) = TestDB::with_many_files(ra_fixture);
-    let file_id = *file_ids.last().unwrap();
-    let r = match eval_goal(&db, file_id) {
-        Ok(t) => t,
-        Err(e) => {
-            let err = pretty_print_err(e, db);
-            panic!("Error in evaluating goal: {err}");
-        }
-    };
-    match &r.data(Interner).value {
-        chalk_ir::ConstValue::Concrete(c) => match &c.interned {
-            ConstScalar::Bytes(b, mm) => {
-                check(b, mm);
+    salsa::attach(&db, || {
+        let file_id = *file_ids.last().unwrap();
+        let r = match eval_goal(&db, file_id) {
+            Ok(t) => t,
+            Err(e) => {
+                let err = pretty_print_err(e, &db);
+                panic!("Error in evaluating goal: {err}");
             }
-            x => panic!("Expected number but found {x:?}"),
-        },
-        _ => panic!("result of const eval wasn't a concrete const"),
-    }
+        };
+        match &r.data(Interner).value {
+            chalk_ir::ConstValue::Concrete(c) => match &c.interned {
+                ConstScalar::Bytes(b, mm) => {
+                    check(b, mm);
+                }
+                x => panic!("Expected number but found {x:?}"),
+            },
+            _ => panic!("result of const eval wasn't a concrete const"),
+        }
+    });
 }
 
-fn pretty_print_err(e: ConstEvalError, db: TestDB) -> String {
+fn pretty_print_err(e: ConstEvalError, db: &TestDB) -> String {
     let mut err = String::new();
     let span_formatter = |file, range| format!("{file:?} {range:?}");
     let display_target =
-        DisplayTarget::from_crate(&db, *db.all_crates().last().expect("no crate graph present"));
+        DisplayTarget::from_crate(db, *db.all_crates().last().expect("no crate graph present"));
     match e {
         ConstEvalError::MirLowerError(e) => {
-            e.pretty_print(&mut err, &db, span_formatter, display_target)
+            e.pretty_print(&mut err, db, span_formatter, display_target)
         }
         ConstEvalError::MirEvalError(e) => {
-            e.pretty_print(&mut err, &db, span_formatter, display_target)
+            e.pretty_print(&mut err, db, span_formatter, display_target)
         }
     }
     .unwrap();
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/consteval_nextsolver.rs b/src/tools/rust-analyzer/crates/hir-ty/src/consteval_nextsolver.rs
index 6e07d3afe55..155f1336e41 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/consteval_nextsolver.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/consteval_nextsolver.rs
@@ -222,7 +222,7 @@ pub(crate) fn const_eval_discriminant_variant(
 // and make this function private. See the fixme comment on `InferenceContext::resolve_all`.
 pub(crate) fn eval_to_const<'db>(expr: ExprId, ctx: &mut InferenceContext<'db>) -> Const<'db> {
     let interner = DbInterner::new_with(ctx.db, None, None);
-    let infer = ctx.clone().resolve_all();
+    let infer = ctx.fixme_resolve_all_clone();
     fn has_closure(body: &Body, expr: ExprId) -> bool {
         if matches!(body[expr], Expr::Closure { .. }) {
             return true;
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/db.rs b/src/tools/rust-analyzer/crates/hir-ty/src/db.rs
index 448fc4aede0..71fb3d44fb7 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/db.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/db.rs
@@ -16,8 +16,8 @@ use smallvec::SmallVec;
 use triomphe::Arc;
 
 use crate::{
-    Binders, Const, ImplTraitId, ImplTraits, InferenceResult, PolyFnSig, Substitution,
-    TraitEnvironment, TraitRef, Ty, TyDefId, ValueTyDefId, chalk_db,
+    Binders, Const, ImplTraitId, ImplTraits, InferenceResult, Substitution, TraitEnvironment, Ty,
+    TyDefId, ValueTyDefId, chalk_db,
     consteval::ConstEvalError,
     drop::DropGlue,
     dyn_compatibility::DynCompatibilityViolation,
@@ -49,7 +49,7 @@ pub trait HirDatabase: DefDatabase + std::fmt::Debug {
         &self,
         def: DefWithBodyId,
         subst: Substitution,
-        env: Arc<TraitEnvironment>,
+        env: Arc<TraitEnvironment<'_>>,
     ) -> Result<Arc<MirBody>, MirLowerError>;
 
     #[salsa::invoke(crate::mir::monomorphized_mir_body_for_closure_query)]
@@ -57,7 +57,7 @@ pub trait HirDatabase: DefDatabase + std::fmt::Debug {
         &self,
         def: InternedClosureId,
         subst: Substitution,
-        env: Arc<TraitEnvironment>,
+        env: Arc<TraitEnvironment<'_>>,
     ) -> Result<Arc<MirBody>, MirLowerError>;
 
     #[salsa::invoke(crate::mir::borrowck_query)]
@@ -70,7 +70,7 @@ pub trait HirDatabase: DefDatabase + std::fmt::Debug {
         &self,
         def: GeneralConstId,
         subst: Substitution,
-        trait_env: Option<Arc<TraitEnvironment>>,
+        trait_env: Option<Arc<TraitEnvironment<'_>>>,
     ) -> Result<Const, ConstEvalError>;
 
     #[salsa::invoke(crate::consteval::const_eval_static_query)]
@@ -84,7 +84,7 @@ pub trait HirDatabase: DefDatabase + std::fmt::Debug {
     #[salsa::invoke(crate::method_resolution::lookup_impl_method_query)]
     fn lookup_impl_method(
         &self,
-        env: Arc<TraitEnvironment>,
+        env: Arc<TraitEnvironment<'_>>,
         func: FunctionId,
         fn_subst: Substitution,
     ) -> (FunctionId, Substitution);
@@ -97,7 +97,7 @@ pub trait HirDatabase: DefDatabase + std::fmt::Debug {
         &'db self,
         def: AdtId,
         args: crate::next_solver::GenericArgs<'db>,
-        trait_env: Arc<TraitEnvironment>,
+        trait_env: Arc<TraitEnvironment<'db>>,
     ) -> Result<Arc<Layout>, LayoutError>;
 
     #[salsa::invoke(crate::layout::layout_of_ty_query)]
@@ -105,7 +105,7 @@ pub trait HirDatabase: DefDatabase + std::fmt::Debug {
     fn layout_of_ty<'db>(
         &'db self,
         ty: crate::next_solver::Ty<'db>,
-        env: Arc<TraitEnvironment>,
+        env: Arc<TraitEnvironment<'db>>,
     ) -> Result<Arc<Layout>, LayoutError>;
 
     #[salsa::invoke(crate::layout::target_data_layout_query)]
@@ -114,55 +114,94 @@ pub trait HirDatabase: DefDatabase + std::fmt::Debug {
     #[salsa::invoke(crate::dyn_compatibility::dyn_compatibility_of_trait_query)]
     fn dyn_compatibility_of_trait(&self, trait_: TraitId) -> Option<DynCompatibilityViolation>;
 
-    #[salsa::invoke(crate::lower::ty_query)]
+    #[salsa::invoke(crate::lower_nextsolver::ty_query)]
     #[salsa::transparent]
-    fn ty(&self, def: TyDefId) -> Binders<Ty>;
+    fn ty<'db>(
+        &'db self,
+        def: TyDefId,
+    ) -> crate::next_solver::EarlyBinder<'db, crate::next_solver::Ty<'db>>;
 
-    #[salsa::invoke(crate::lower::type_for_type_alias_with_diagnostics_query)]
-    #[salsa::cycle(cycle_result = crate::lower::type_for_type_alias_with_diagnostics_cycle_result)]
-    fn type_for_type_alias_with_diagnostics(&self, def: TypeAliasId) -> (Binders<Ty>, Diagnostics);
+    #[salsa::invoke(crate::lower_nextsolver::type_for_type_alias_with_diagnostics_query)]
+    #[salsa::cycle(cycle_result = crate::lower_nextsolver::type_for_type_alias_with_diagnostics_cycle_result)]
+    fn type_for_type_alias_with_diagnostics<'db>(
+        &'db self,
+        def: TypeAliasId,
+    ) -> (crate::next_solver::EarlyBinder<'db, crate::next_solver::Ty<'db>>, Diagnostics);
 
     /// Returns the type of the value of the given constant, or `None` if the `ValueTyDefId` is
     /// a `StructId` or `EnumVariantId` with a record constructor.
-    #[salsa::invoke(crate::lower::value_ty_query)]
-    fn value_ty(&self, def: ValueTyDefId) -> Option<Binders<Ty>>;
+    #[salsa::invoke(crate::lower_nextsolver::value_ty_query)]
+    fn value_ty<'db>(
+        &'db self,
+        def: ValueTyDefId,
+    ) -> Option<crate::next_solver::EarlyBinder<'db, crate::next_solver::Ty<'db>>>;
 
-    #[salsa::invoke(crate::lower::impl_self_ty_with_diagnostics_query)]
-    #[salsa::cycle(cycle_result = crate::lower::impl_self_ty_with_diagnostics_cycle_result)]
-    fn impl_self_ty_with_diagnostics(&self, def: ImplId) -> (Binders<Ty>, Diagnostics);
+    #[salsa::invoke(crate::lower_nextsolver::impl_self_ty_with_diagnostics_query)]
+    #[salsa::cycle(cycle_result = crate::lower_nextsolver::impl_self_ty_with_diagnostics_cycle_result)]
+    fn impl_self_ty_with_diagnostics<'db>(
+        &'db self,
+        def: ImplId,
+    ) -> (crate::next_solver::EarlyBinder<'db, crate::next_solver::Ty<'db>>, Diagnostics);
 
-    #[salsa::invoke(crate::lower::impl_self_ty_query)]
+    #[salsa::invoke(crate::lower_nextsolver::impl_self_ty_query)]
     #[salsa::transparent]
-    fn impl_self_ty(&self, def: ImplId) -> Binders<Ty>;
+    fn impl_self_ty<'db>(
+        &'db self,
+        def: ImplId,
+    ) -> crate::next_solver::EarlyBinder<'db, crate::next_solver::Ty<'db>>;
 
     // FIXME: Make this a non-interned query.
-    #[salsa::invoke_interned(crate::lower::const_param_ty_with_diagnostics_query)]
-    #[salsa::cycle(cycle_result = crate::lower::const_param_ty_with_diagnostics_cycle_result)]
-    fn const_param_ty_with_diagnostics(&self, def: ConstParamId) -> (Ty, Diagnostics);
+    #[salsa::invoke_interned(crate::lower_nextsolver::const_param_ty_with_diagnostics_query)]
+    #[salsa::cycle(cycle_result = crate::lower_nextsolver::const_param_ty_with_diagnostics_cycle_result)]
+    fn const_param_ty_with_diagnostics<'db>(
+        &'db self,
+        def: ConstParamId,
+    ) -> (crate::next_solver::Ty<'db>, Diagnostics);
 
-    #[salsa::invoke(crate::lower::const_param_ty_query)]
-    #[salsa::transparent]
+    // FIXME: Make this a non-interned query.
+    #[salsa::invoke_interned(crate::lower::const_param_ty_query)]
+    #[salsa::cycle(cycle_result = crate::lower::const_param_ty_cycle_result)]
     fn const_param_ty(&self, def: ConstParamId) -> Ty;
 
-    #[salsa::invoke(crate::lower::impl_trait_with_diagnostics_query)]
-    fn impl_trait_with_diagnostics(&self, def: ImplId) -> Option<(Binders<TraitRef>, Diagnostics)>;
+    #[salsa::invoke(crate::lower_nextsolver::impl_trait_with_diagnostics_query)]
+    fn impl_trait_with_diagnostics<'db>(
+        &'db self,
+        def: ImplId,
+    ) -> Option<(
+        crate::next_solver::EarlyBinder<'db, crate::next_solver::TraitRef<'db>>,
+        Diagnostics,
+    )>;
 
-    #[salsa::invoke(crate::lower::impl_trait_query)]
+    #[salsa::invoke(crate::lower_nextsolver::impl_trait_query)]
     #[salsa::transparent]
-    fn impl_trait(&self, def: ImplId) -> Option<Binders<TraitRef>>;
+    fn impl_trait<'db>(
+        &'db self,
+        def: ImplId,
+    ) -> Option<crate::next_solver::EarlyBinder<'db, crate::next_solver::TraitRef<'db>>>;
 
-    #[salsa::invoke(crate::lower::field_types_with_diagnostics_query)]
-    fn field_types_with_diagnostics(
-        &self,
+    #[salsa::invoke(crate::lower_nextsolver::field_types_with_diagnostics_query)]
+    fn field_types_with_diagnostics<'db>(
+        &'db self,
         var: VariantId,
-    ) -> (Arc<ArenaMap<LocalFieldId, Binders<Ty>>>, Diagnostics);
+    ) -> (
+        Arc<
+            ArenaMap<
+                LocalFieldId,
+                crate::next_solver::EarlyBinder<'db, crate::next_solver::Ty<'db>>,
+            >,
+        >,
+        Diagnostics,
+    );
 
     #[salsa::invoke(crate::lower::field_types_query)]
     #[salsa::transparent]
     fn field_types(&self, var: VariantId) -> Arc<ArenaMap<LocalFieldId, Binders<Ty>>>;
 
-    #[salsa::invoke(crate::lower::callable_item_signature_query)]
-    fn callable_item_signature(&self, def: CallableDefId) -> PolyFnSig;
+    #[salsa::invoke(crate::lower_nextsolver::callable_item_signature_query)]
+    fn callable_item_signature<'db>(
+        &'db self,
+        def: CallableDefId,
+    ) -> crate::next_solver::EarlyBinder<'db, crate::next_solver::PolyFnSig<'db>>;
 
     #[salsa::invoke(crate::lower::return_type_impl_traits)]
     fn return_type_impl_traits(&self, def: FunctionId) -> Option<Arc<Binders<ImplTraits>>>;
@@ -182,12 +221,28 @@ pub trait HirDatabase: DefDatabase + std::fmt::Debug {
     #[salsa::invoke(crate::lower::generic_predicates_query)]
     fn generic_predicates(&self, def: GenericDefId) -> GenericPredicates;
 
-    #[salsa::invoke(crate::lower::trait_environment_for_body_query)]
+    #[salsa::invoke(
+        crate::lower_nextsolver::generic_predicates_without_parent_with_diagnostics_query
+    )]
+    fn generic_predicates_without_parent_with_diagnostics<'db>(
+        &'db self,
+        def: GenericDefId,
+    ) -> (crate::lower_nextsolver::GenericPredicates<'db>, Diagnostics);
+
+    #[salsa::invoke(crate::lower_nextsolver::generic_predicates_without_parent_query)]
+    #[salsa::transparent]
+    fn generic_predicates_without_parent<'db>(
+        &'db self,
+        def: GenericDefId,
+    ) -> crate::lower_nextsolver::GenericPredicates<'db>;
+
+    #[salsa::invoke(crate::lower_nextsolver::trait_environment_for_body_query)]
     #[salsa::transparent]
-    fn trait_environment_for_body(&self, def: DefWithBodyId) -> Arc<TraitEnvironment>;
+    fn trait_environment_for_body<'db>(&'db self, def: DefWithBodyId)
+    -> Arc<TraitEnvironment<'db>>;
 
-    #[salsa::invoke(crate::lower::trait_environment_query)]
-    fn trait_environment(&self, def: GenericDefId) -> Arc<TraitEnvironment>;
+    #[salsa::invoke(crate::lower_nextsolver::trait_environment_query)]
+    fn trait_environment<'db>(&'db self, def: GenericDefId) -> Arc<TraitEnvironment<'db>>;
 
     #[salsa::invoke(crate::lower::generic_defaults_with_diagnostics_query)]
     #[salsa::cycle(cycle_result = crate::lower::generic_defaults_with_diagnostics_cycle_result)]
@@ -258,7 +313,7 @@ pub trait HirDatabase: DefDatabase + std::fmt::Debug {
     fn normalize_projection(
         &self,
         projection: crate::ProjectionTy,
-        env: Arc<TraitEnvironment>,
+        env: Arc<TraitEnvironment<'_>>,
     ) -> Ty;
 
     #[salsa::invoke(crate::traits::trait_solve_query)]
@@ -272,87 +327,14 @@ pub trait HirDatabase: DefDatabase + std::fmt::Debug {
 
     #[salsa::invoke(crate::drop::has_drop_glue)]
     #[salsa::cycle(cycle_result = crate::drop::has_drop_glue_cycle_result)]
-    fn has_drop_glue(&self, ty: Ty, env: Arc<TraitEnvironment>) -> DropGlue;
+    fn has_drop_glue(&self, ty: Ty, env: Arc<TraitEnvironment<'_>>) -> DropGlue;
 
     // next trait solver
 
-    #[salsa::invoke(crate::lower_nextsolver::ty_query)]
-    #[salsa::transparent]
-    fn ty_ns<'db>(
-        &'db self,
-        def: TyDefId,
-    ) -> crate::next_solver::EarlyBinder<'db, crate::next_solver::Ty<'db>>;
-
-    /// Returns the type of the value of the given constant, or `None` if the `ValueTyDefId` is
-    /// a `StructId` or `EnumVariantId` with a record constructor.
-    #[salsa::invoke(crate::lower_nextsolver::value_ty_query)]
-    fn value_ty_ns<'db>(
-        &'db self,
-        def: ValueTyDefId,
-    ) -> Option<crate::next_solver::EarlyBinder<'db, crate::next_solver::Ty<'db>>>;
-
-    #[salsa::invoke(crate::lower_nextsolver::type_for_type_alias_with_diagnostics_query)]
-    #[salsa::cycle(cycle_result = crate::lower_nextsolver::type_for_type_alias_with_diagnostics_cycle_result)]
-    fn type_for_type_alias_with_diagnostics_ns<'db>(
-        &'db self,
-        def: TypeAliasId,
-    ) -> (crate::next_solver::EarlyBinder<'db, crate::next_solver::Ty<'db>>, Diagnostics);
-
-    #[salsa::invoke(crate::lower_nextsolver::impl_self_ty_with_diagnostics_query)]
-    #[salsa::cycle(cycle_result = crate::lower_nextsolver::impl_self_ty_with_diagnostics_cycle_result)]
-    fn impl_self_ty_with_diagnostics_ns<'db>(
-        &'db self,
-        def: ImplId,
-    ) -> (crate::next_solver::EarlyBinder<'db, crate::next_solver::Ty<'db>>, Diagnostics);
-
-    #[salsa::invoke(crate::lower_nextsolver::impl_self_ty_query)]
-    #[salsa::transparent]
-    fn impl_self_ty_ns<'db>(
-        &'db self,
-        def: ImplId,
-    ) -> crate::next_solver::EarlyBinder<'db, crate::next_solver::Ty<'db>>;
-
-    // FIXME: Make this a non-interned query.
-    #[salsa::invoke_interned(crate::lower_nextsolver::const_param_ty_with_diagnostics_query)]
-    fn const_param_ty_with_diagnostics_ns<'db>(
-        &'db self,
-        def: ConstParamId,
-    ) -> (crate::next_solver::Ty<'db>, Diagnostics);
-
     #[salsa::invoke(crate::lower_nextsolver::const_param_ty_query)]
     #[salsa::transparent]
     fn const_param_ty_ns<'db>(&'db self, def: ConstParamId) -> crate::next_solver::Ty<'db>;
 
-    #[salsa::invoke(crate::lower_nextsolver::impl_trait_with_diagnostics_query)]
-    fn impl_trait_with_diagnostics_ns<'db>(
-        &'db self,
-        def: ImplId,
-    ) -> Option<(
-        crate::next_solver::EarlyBinder<'db, crate::next_solver::TraitRef<'db>>,
-        Diagnostics,
-    )>;
-
-    #[salsa::invoke(crate::lower_nextsolver::impl_trait_query)]
-    #[salsa::transparent]
-    fn impl_trait_ns<'db>(
-        &'db self,
-        def: ImplId,
-    ) -> Option<crate::next_solver::EarlyBinder<'db, crate::next_solver::TraitRef<'db>>>;
-
-    #[salsa::invoke(crate::lower_nextsolver::field_types_with_diagnostics_query)]
-    fn field_types_with_diagnostics_ns<'db>(
-        &'db self,
-        var: VariantId,
-    ) -> (
-        Arc<
-            ArenaMap<
-                LocalFieldId,
-                crate::next_solver::EarlyBinder<'db, crate::next_solver::Ty<'db>>,
-            >,
-        >,
-        Diagnostics,
-    );
-
     #[salsa::invoke(crate::lower_nextsolver::field_types_query)]
     #[salsa::transparent]
     fn field_types_ns<'db>(
@@ -362,12 +344,6 @@ pub trait HirDatabase: DefDatabase + std::fmt::Debug {
         ArenaMap<LocalFieldId, crate::next_solver::EarlyBinder<'db, crate::next_solver::Ty<'db>>>,
     >;
 
-    #[salsa::invoke(crate::lower_nextsolver::callable_item_signature_query)]
-    fn callable_item_signature_ns<'db>(
-        &'db self,
-        def: CallableDefId,
-    ) -> crate::next_solver::EarlyBinder<'db, crate::next_solver::PolyFnSig<'db>>;
-
     #[salsa::invoke(crate::lower_nextsolver::return_type_impl_traits)]
     fn return_type_impl_traits_ns<'db>(
         &'db self,
@@ -394,21 +370,6 @@ pub trait HirDatabase: DefDatabase + std::fmt::Debug {
         &'db self,
         def: GenericDefId,
     ) -> crate::lower_nextsolver::GenericPredicates<'db>;
-
-    #[salsa::invoke(
-        crate::lower_nextsolver::generic_predicates_without_parent_with_diagnostics_query
-    )]
-    fn generic_predicates_without_parent_with_diagnostics_ns<'db>(
-        &'db self,
-        def: GenericDefId,
-    ) -> (crate::lower_nextsolver::GenericPredicates<'db>, Diagnostics);
-
-    #[salsa::invoke(crate::lower_nextsolver::generic_predicates_without_parent_query)]
-    #[salsa::transparent]
-    fn generic_predicates_without_parent_ns<'db>(
-        &'db self,
-        def: GenericDefId,
-    ) -> crate::lower_nextsolver::GenericPredicates<'db>;
 }
 
 #[test]
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/expr.rs b/src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/expr.rs
index 403ea05a4f5..d05814e0e7e 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/expr.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/expr.rs
@@ -81,17 +81,17 @@ impl BodyValidationDiagnostic {
     }
 }
 
-struct ExprValidator {
+struct ExprValidator<'db> {
     owner: DefWithBodyId,
     body: Arc<Body>,
     infer: Arc<InferenceResult>,
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'db>>,
     diagnostics: Vec<BodyValidationDiagnostic>,
     validate_lints: bool,
 }
 
-impl ExprValidator {
-    fn validate_body(&mut self, db: &dyn HirDatabase) {
+impl<'db> ExprValidator<'db> {
+    fn validate_body(&mut self, db: &'db dyn HirDatabase) {
         let mut filter_map_next_checker = None;
         // we'll pass &mut self while iterating over body.exprs, so they need to be disjoint
         let body = Arc::clone(&self.body);
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/match_check/pat_analysis.rs b/src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/match_check/pat_analysis.rs
index 56fd12e1f2b..eb20d3c51ff 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/match_check/pat_analysis.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/match_check/pat_analysis.rs
@@ -70,7 +70,7 @@ pub(crate) struct MatchCheckCtx<'db> {
     body: DefWithBodyId,
     pub(crate) db: &'db dyn HirDatabase,
     exhaustive_patterns: bool,
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'db>>,
 }
 
 impl<'db> MatchCheckCtx<'db> {
@@ -78,7 +78,7 @@ impl<'db> MatchCheckCtx<'db> {
         module: ModuleId,
         body: DefWithBodyId,
         db: &'db dyn HirDatabase,
-        env: Arc<TraitEnvironment>,
+        env: Arc<TraitEnvironment<'db>>,
     ) -> Self {
         let def_map = module.crate_def_map(db);
         let exhaustive_patterns = def_map.is_unstable_feature_enabled(&sym::exhaustive_patterns);
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/unsafe_check.rs b/src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/unsafe_check.rs
index 3f04b72c2fc..3c78f5ef387 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/unsafe_check.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/unsafe_check.rs
@@ -315,6 +315,22 @@ impl<'db> UnsafeVisitor<'db> {
                     }
                     _ => (),
                 }
+
+                let mut peeled = *expr;
+                while let Expr::Field { expr: lhs, .. } = &self.body[peeled] {
+                    if let Some(Either::Left(FieldId { parent: VariantId::UnionId(_), .. })) =
+                        self.infer.field_resolution(peeled)
+                    {
+                        peeled = *lhs;
+                    } else {
+                        break;
+                    }
+                }
+
+                // Walk the peeled expression (the LHS of the union field chain)
+                self.walk_expr(peeled);
+                // Return so we don't recurse directly onto the union field access(es)
+                return;
             }
             Expr::MethodCall { .. } => {
                 if let Some((func, _)) = self.infer.method_resolution(current) {
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/display.rs b/src/tools/rust-analyzer/crates/hir-ty/src/display.rs
index 519e4b59237..e11ce51cdb8 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/display.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/display.rs
@@ -46,8 +46,8 @@ use span::Edition;
 use stdx::never;
 use triomphe::Arc;
 
-use crate::next_solver::infer::DbInternerInferExt;
 use crate::next_solver::infer::traits::ObligationCause;
+use crate::next_solver::{infer::DbInternerInferExt, mapping::NextSolverToChalk};
 use crate::{
     AliasEq, AliasTy, Binders, CallableDefId, CallableSig, ConcreteConst, Const, ConstScalar,
     ConstValue, DomainGoal, FnAbi, GenericArg, ImplTraitId, Interner, Lifetime, LifetimeData,
@@ -792,19 +792,16 @@ fn render_const_scalar_ns(
     let trait_env = TraitEnvironment::empty(f.krate());
     let interner = DbInterner::new_with(f.db, Some(trait_env.krate), trait_env.block);
     let infcx = interner.infer_ctxt().build(rustc_type_ir::TypingMode::PostAnalysis);
-    let ty = infcx
-        .at(&ObligationCause::new(), trait_env.env.to_nextsolver(interner))
-        .deeply_normalize(ty)
-        .unwrap_or(ty);
+    let ty = infcx.at(&ObligationCause::new(), trait_env.env).deeply_normalize(ty).unwrap_or(ty);
     render_const_scalar_inner(f, b, memory_map, ty, trait_env)
 }
 
-fn render_const_scalar_inner(
+fn render_const_scalar_inner<'db>(
     f: &mut HirFormatter<'_>,
     b: &[u8],
     memory_map: &MemoryMap<'_>,
-    ty: crate::next_solver::Ty<'_>,
-    trait_env: Arc<TraitEnvironment>,
+    ty: crate::next_solver::Ty<'db>,
+    trait_env: Arc<TraitEnvironment<'db>>,
 ) -> Result<(), HirDisplayError> {
     use rustc_type_ir::TyKind;
     match ty.kind() {
@@ -1068,11 +1065,11 @@ fn render_const_scalar_inner(
     }
 }
 
-fn render_variant_after_name(
+fn render_variant_after_name<'db>(
     data: &VariantFields,
     f: &mut HirFormatter<'_>,
     field_types: &ArenaMap<LocalFieldId, Binders<Ty>>,
-    trait_env: Arc<TraitEnvironment>,
+    trait_env: Arc<TraitEnvironment<'db>>,
     layout: &Layout,
     args: GenericArgs<'_>,
     b: &[u8],
@@ -1301,7 +1298,9 @@ impl<'db> HirDisplay for crate::next_solver::Ty<'db> {
                 let def = def.0;
                 let sig = db
                     .callable_item_signature(def)
-                    .substitute(Interner, &convert_args_for_result(interner, args.as_slice()));
+                    .instantiate(interner, args)
+                    .skip_binder()
+                    .to_chalk(interner);
 
                 if f.display_kind.is_source_code() {
                     // `FnDef` is anonymous and there's no surface syntax for it. Show it as a
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/drop.rs b/src/tools/rust-analyzer/crates/hir-ty/src/drop.rs
index f5c2f41069e..413f70532a5 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/drop.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/drop.rs
@@ -7,6 +7,8 @@ use hir_def::signatures::StructFlags;
 use stdx::never;
 use triomphe::Arc;
 
+use crate::next_solver::DbInterner;
+use crate::next_solver::mapping::NextSolverToChalk;
 use crate::{
     AliasTy, Canonical, CanonicalVarKinds, ConcreteConst, ConstScalar, ConstValue, InEnvironment,
     Interner, ProjectionTy, TraitEnvironment, Ty, TyBuilder, TyKind, db::HirDatabase,
@@ -43,7 +45,11 @@ pub enum DropGlue {
     HasDropGlue,
 }
 
-pub(crate) fn has_drop_glue(db: &dyn HirDatabase, ty: Ty, env: Arc<TraitEnvironment>) -> DropGlue {
+pub(crate) fn has_drop_glue(
+    db: &dyn HirDatabase,
+    ty: Ty,
+    env: Arc<TraitEnvironment<'_>>,
+) -> DropGlue {
     match ty.kind(Interner) {
         TyKind::Adt(adt, subst) => {
             if has_destructor(db, adt.0) {
@@ -165,7 +171,7 @@ pub(crate) fn has_drop_glue(db: &dyn HirDatabase, ty: Ty, env: Arc<TraitEnvironm
 
 fn projection_has_drop_glue(
     db: &dyn HirDatabase,
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'_>>,
     projection: ProjectionTy,
     ty: Ty,
 ) -> DropGlue {
@@ -178,13 +184,16 @@ fn projection_has_drop_glue(
     }
 }
 
-fn is_copy(db: &dyn HirDatabase, ty: Ty, env: Arc<TraitEnvironment>) -> bool {
+fn is_copy(db: &dyn HirDatabase, ty: Ty, env: Arc<TraitEnvironment<'_>>) -> bool {
     let Some(copy_trait) = LangItem::Copy.resolve_trait(db, env.krate) else {
         return false;
     };
     let trait_ref = TyBuilder::trait_ref(db, copy_trait).push(ty).build();
     let goal = Canonical {
-        value: InEnvironment::new(&env.env, trait_ref.cast(Interner)),
+        value: InEnvironment::new(
+            &env.env.to_chalk(DbInterner::new_with(db, Some(env.krate), env.block)),
+            trait_ref.cast(Interner),
+        ),
         binders: CanonicalVarKinds::empty(Interner),
     };
     db.trait_solve(env.krate, env.block, goal).certain()
@@ -193,7 +202,7 @@ fn is_copy(db: &dyn HirDatabase, ty: Ty, env: Arc<TraitEnvironment>) -> bool {
 pub(crate) fn has_drop_glue_cycle_result(
     _db: &dyn HirDatabase,
     _ty: Ty,
-    _env: Arc<TraitEnvironment>,
+    _env: Arc<TraitEnvironment<'_>>,
 ) -> DropGlue {
     DropGlue::None
 }
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/dyn_compatibility.rs b/src/tools/rust-analyzer/crates/hir-ty/src/dyn_compatibility.rs
index b87c9982177..b2406a08895 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/dyn_compatibility.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/dyn_compatibility.rs
@@ -329,7 +329,7 @@ where
         cb(MethodViolationCode::AsyncFn)?;
     }
 
-    let sig = db.callable_item_signature_ns(func.into());
+    let sig = db.callable_item_signature(func.into());
     if sig
         .skip_binder()
         .inputs()
@@ -364,7 +364,7 @@ where
         cb(MethodViolationCode::UndispatchableReceiver)?;
     }
 
-    let predicates = &*db.generic_predicates_without_parent_ns(func.into());
+    let predicates = &*db.generic_predicates_without_parent(func.into());
     for pred in predicates {
         let pred = pred.kind().skip_binder();
 
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/infer.rs b/src/tools/rust-analyzer/crates/hir-ty/src/infer.rs
index 017119781a7..0282b7a9363 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/infer.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/infer.rs
@@ -19,6 +19,7 @@ pub(crate) mod closure;
 mod coerce;
 pub(crate) mod diagnostics;
 mod expr;
+mod fallback;
 mod mutability;
 mod pat;
 mod path;
@@ -53,16 +54,16 @@ use indexmap::IndexSet;
 use intern::sym;
 use la_arena::{ArenaMap, Entry};
 use rustc_hash::{FxHashMap, FxHashSet};
+use rustc_type_ir::inherent::Ty as _;
 use stdx::{always, never};
 use triomphe::Arc;
 
-use crate::db::InternedClosureId;
 use crate::{
     AliasEq, AliasTy, Binders, ClosureId, Const, DomainGoal, GenericArg, ImplTraitId, ImplTraitIdx,
     IncorrectGenericsLenKind, Interner, Lifetime, OpaqueTyId, ParamLoweringMode,
     PathLoweringDiagnostic, ProjectionTy, Substitution, TargetFeatures, TraitEnvironment, Ty,
     TyBuilder, TyExt,
-    db::HirDatabase,
+    db::{HirDatabase, InternedClosureId},
     fold_tys,
     generics::Generics,
     infer::{
@@ -75,6 +76,7 @@ use crate::{
     mir::MirSpan,
     next_solver::{
         self, DbInterner,
+        infer::{DefineOpaqueTypes, traits::ObligationCause},
         mapping::{ChalkToNextSolver, NextSolverToChalk},
     },
     static_lifetime, to_assoc_type_id,
@@ -138,6 +140,20 @@ pub(crate) fn infer_query(db: &dyn HirDatabase, def: DefWithBodyId) -> Arc<Infer
 
     ctx.infer_mut_body();
 
+    ctx.type_inference_fallback();
+
+    // Comment from rustc:
+    // Even though coercion casts provide type hints, we check casts after fallback for
+    // backwards compatibility. This makes fallback a stronger type hint than a cast coercion.
+    let cast_checks = std::mem::take(&mut ctx.deferred_cast_checks);
+    for mut cast in cast_checks.into_iter() {
+        if let Err(diag) = cast.check(&mut ctx) {
+            ctx.diagnostics.push(diag);
+        }
+    }
+
+    ctx.table.select_obligations_where_possible();
+
     ctx.infer_closures();
 
     Arc::new(ctx.resolve_all())
@@ -152,7 +168,7 @@ pub(crate) fn infer_cycle_result(_: &dyn HirDatabase, _: DefWithBodyId) -> Arc<I
 /// This is appropriate to use only after type-check: it assumes
 /// that normalization will succeed, for example.
 #[tracing::instrument(level = "debug", skip(db))]
-pub(crate) fn normalize(db: &dyn HirDatabase, trait_env: Arc<TraitEnvironment>, ty: Ty) -> Ty {
+pub(crate) fn normalize(db: &dyn HirDatabase, trait_env: Arc<TraitEnvironment<'_>>, ty: Ty) -> Ty {
     // FIXME: TypeFlags::HAS_CT_PROJECTION is not implemented in chalk, so TypeFlags::HAS_PROJECTION only
     // works for the type case, so we check array unconditionally. Remove the array part
     // when the bug in chalk becomes fixed.
@@ -165,7 +181,6 @@ pub(crate) fn normalize(db: &dyn HirDatabase, trait_env: Arc<TraitEnvironment>,
 
     let ty_with_vars = table.normalize_associated_types_in(ty);
     table.select_obligations_where_possible();
-    table.propagate_diverging_flag();
     table.resolve_completely(ty_with_vars)
 }
 
@@ -632,6 +647,26 @@ impl InferenceResult {
     pub fn binding_mode(&self, id: PatId) -> Option<BindingMode> {
         self.binding_modes.get(id).copied()
     }
+
+    // This method is consumed by external tools to run rust-analyzer as a library. Don't remove, please.
+    pub fn expression_types(&self) -> impl Iterator<Item = (ExprId, &Ty)> {
+        self.type_of_expr.iter()
+    }
+
+    // This method is consumed by external tools to run rust-analyzer as a library. Don't remove, please.
+    pub fn pattern_types(&self) -> impl Iterator<Item = (PatId, &Ty)> {
+        self.type_of_pat.iter()
+    }
+
+    // This method is consumed by external tools to run rust-analyzer as a library. Don't remove, please.
+    pub fn binding_types(&self) -> impl Iterator<Item = (BindingId, &Ty)> {
+        self.type_of_binding.iter()
+    }
+
+    // This method is consumed by external tools to run rust-analyzer as a library. Don't remove, please.
+    pub fn return_position_impl_trait_types(&self) -> impl Iterator<Item = (ImplTraitIdx, &Ty)> {
+        self.type_of_rpit.iter()
+    }
 }
 
 impl Index<ExprId> for InferenceResult {
@@ -666,6 +701,25 @@ impl Index<BindingId> for InferenceResult {
     }
 }
 
+#[derive(Debug, Clone)]
+struct InternedStandardTypesNextSolver<'db> {
+    unit: crate::next_solver::Ty<'db>,
+    never: crate::next_solver::Ty<'db>,
+    i32: crate::next_solver::Ty<'db>,
+    f64: crate::next_solver::Ty<'db>,
+}
+
+impl<'db> InternedStandardTypesNextSolver<'db> {
+    fn new(interner: DbInterner<'db>) -> Self {
+        Self {
+            unit: crate::next_solver::Ty::new_unit(interner),
+            never: crate::next_solver::Ty::new(interner, crate::next_solver::TyKind::Never),
+            i32: crate::next_solver::Ty::new_int(interner, rustc_type_ir::IntTy::I32),
+            f64: crate::next_solver::Ty::new_float(interner, rustc_type_ir::FloatTy::F64),
+        }
+    }
+}
+
 /// The inference context contains all information needed during type inference.
 #[derive(Clone, Debug)]
 pub(crate) struct InferenceContext<'db> {
@@ -698,6 +752,7 @@ pub(crate) struct InferenceContext<'db> {
     resume_yield_tys: Option<(Ty, Ty)>,
     diverges: Diverges,
     breakables: Vec<BreakableContext<'db>>,
+    types: InternedStandardTypesNextSolver<'db>,
 
     /// Whether we are inside the pattern of a destructuring assignment.
     inside_assignment: bool,
@@ -778,11 +833,13 @@ impl<'db> InferenceContext<'db> {
         resolver: Resolver<'db>,
     ) -> Self {
         let trait_env = db.trait_environment_for_body(owner);
+        let table = unify::InferenceTable::new(db, trait_env);
         InferenceContext {
+            types: InternedStandardTypesNextSolver::new(table.interner),
             target_features: OnceCell::new(),
             generics: OnceCell::new(),
             result: InferenceResult::default(),
-            table: unify::InferenceTable::new(db, trait_env),
+            table,
             tuple_field_accesses_rev: Default::default(),
             return_ty: TyKind::Error.intern(Interner), // set in collect_* calls
             resume_yield_tys: None,
@@ -845,24 +902,33 @@ impl<'db> InferenceContext<'db> {
         self.result.has_errors = true;
     }
 
-    // FIXME: This function should be private in module. It is currently only used in the consteval, since we need
-    // `InferenceResult` in the middle of inference. See the fixme comment in `consteval::eval_to_const`. If you
-    // used this function for another workaround, mention it here. If you really need this function and believe that
-    // there is no problem in it being `pub(crate)`, remove this comment.
-    pub(crate) fn resolve_all(mut self) -> InferenceResult {
-        self.table.select_obligations_where_possible();
-        self.table.fallback_if_possible();
+    /// Clones `self` and calls `resolve_all()` on it.
+    // FIXME: Remove this.
+    pub(crate) fn fixme_resolve_all_clone(&self) -> InferenceResult {
+        let mut ctx = self.clone();
+
+        ctx.type_inference_fallback();
 
         // Comment from rustc:
         // Even though coercion casts provide type hints, we check casts after fallback for
         // backwards compatibility. This makes fallback a stronger type hint than a cast coercion.
-        let cast_checks = std::mem::take(&mut self.deferred_cast_checks);
+        let cast_checks = std::mem::take(&mut ctx.deferred_cast_checks);
         for mut cast in cast_checks.into_iter() {
-            if let Err(diag) = cast.check(&mut self) {
-                self.diagnostics.push(diag);
+            if let Err(diag) = cast.check(&mut ctx) {
+                ctx.diagnostics.push(diag);
             }
         }
 
+        ctx.table.select_obligations_where_possible();
+
+        ctx.resolve_all()
+    }
+
+    // FIXME: This function should be private in module. It is currently only used in the consteval, since we need
+    // `InferenceResult` in the middle of inference. See the fixme comment in `consteval::eval_to_const`. If you
+    // used this function for another workaround, mention it here. If you really need this function and believe that
+    // there is no problem in it being `pub(crate)`, remove this comment.
+    pub(crate) fn resolve_all(self) -> InferenceResult {
         let InferenceContext {
             mut table, mut result, tuple_field_accesses_rev, diagnostics, ..
         } = self;
@@ -894,11 +960,6 @@ impl<'db> InferenceContext<'db> {
             diagnostics: _,
         } = &mut result;
 
-        // FIXME resolve obligations as well (use Guidance if necessary)
-        table.select_obligations_where_possible();
-
-        // make sure diverging type variables are marked as such
-        table.propagate_diverging_flag();
         for ty in type_of_expr.values_mut() {
             *ty = table.resolve_completely(ty.clone());
             *has_errors = *has_errors || ty.contains_unknown();
@@ -1653,6 +1714,22 @@ impl<'db> InferenceContext<'db> {
         self.resolve_associated_type_with_params(inner_ty, assoc_ty, &[])
     }
 
+    fn demand_eqtype(
+        &mut self,
+        expected: crate::next_solver::Ty<'db>,
+        actual: crate::next_solver::Ty<'db>,
+    ) {
+        let result = self
+            .table
+            .infer_ctxt
+            .at(&ObligationCause::new(), self.table.trait_env.env)
+            .eq(DefineOpaqueTypes::Yes, expected, actual)
+            .map(|infer_ok| self.table.register_infer_ok(infer_ok));
+        if let Err(_err) = result {
+            // FIXME: Emit diagnostic.
+        }
+    }
+
     fn resolve_associated_type_with_params(
         &mut self,
         inner_ty: Ty,
@@ -1708,6 +1785,7 @@ impl<'db> InferenceContext<'db> {
             LifetimeElisionKind::Infer,
         );
         let mut path_ctx = ctx.at_path(path, node);
+        let interner = DbInterner::conjure();
         let (resolution, unresolved) = if value_ns {
             let Some(res) = path_ctx.resolve_path_in_value_ns(HygieneId::ROOT) else {
                 return (self.err_ty(), None);
@@ -1717,15 +1795,27 @@ impl<'db> InferenceContext<'db> {
                     ValueNs::EnumVariantId(var) => {
                         let substs = path_ctx.substs_from_path(var.into(), true, false);
                         drop(ctx);
-                        let ty = self.db.ty(var.lookup(self.db).parent.into());
-                        let ty = self.insert_type_vars(ty.substitute(Interner, &substs));
+                        let args: crate::next_solver::GenericArgs<'_> =
+                            substs.to_nextsolver(interner);
+                        let ty = self
+                            .db
+                            .ty(var.lookup(self.db).parent.into())
+                            .instantiate(interner, args)
+                            .to_chalk(interner);
+                        let ty = self.insert_type_vars(ty);
                         return (ty, Some(var.into()));
                     }
                     ValueNs::StructId(strukt) => {
                         let substs = path_ctx.substs_from_path(strukt.into(), true, false);
                         drop(ctx);
-                        let ty = self.db.ty(strukt.into());
-                        let ty = self.insert_type_vars(ty.substitute(Interner, &substs));
+                        let args: crate::next_solver::GenericArgs<'_> =
+                            substs.to_nextsolver(interner);
+                        let ty = self
+                            .db
+                            .ty(strukt.into())
+                            .instantiate(interner, args)
+                            .to_chalk(interner);
+                        let ty = self.insert_type_vars(ty);
                         return (ty, Some(strukt.into()));
                     }
                     ValueNs::ImplSelf(impl_id) => (TypeNs::SelfType(impl_id), None),
@@ -1746,28 +1836,37 @@ impl<'db> InferenceContext<'db> {
             TypeNs::AdtId(AdtId::StructId(strukt)) => {
                 let substs = path_ctx.substs_from_path(strukt.into(), true, false);
                 drop(ctx);
-                let ty = self.db.ty(strukt.into());
-                let ty = self.insert_type_vars(ty.substitute(Interner, &substs));
+                let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+                let ty = self.db.ty(strukt.into()).instantiate(interner, args).to_chalk(interner);
+                let ty = self.insert_type_vars(ty);
                 forbid_unresolved_segments((ty, Some(strukt.into())), unresolved)
             }
             TypeNs::AdtId(AdtId::UnionId(u)) => {
                 let substs = path_ctx.substs_from_path(u.into(), true, false);
                 drop(ctx);
-                let ty = self.db.ty(u.into());
-                let ty = self.insert_type_vars(ty.substitute(Interner, &substs));
+                let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+                let ty = self.db.ty(u.into()).instantiate(interner, args).to_chalk(interner);
+                let ty = self.insert_type_vars(ty);
                 forbid_unresolved_segments((ty, Some(u.into())), unresolved)
             }
             TypeNs::EnumVariantId(var) => {
                 let substs = path_ctx.substs_from_path(var.into(), true, false);
                 drop(ctx);
-                let ty = self.db.ty(var.lookup(self.db).parent.into());
-                let ty = self.insert_type_vars(ty.substitute(Interner, &substs));
+                let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+                let ty = self
+                    .db
+                    .ty(var.lookup(self.db).parent.into())
+                    .instantiate(interner, args)
+                    .to_chalk(interner);
+                let ty = self.insert_type_vars(ty);
                 forbid_unresolved_segments((ty, Some(var.into())), unresolved)
             }
             TypeNs::SelfType(impl_id) => {
                 let generics = crate::generics::generics(self.db, impl_id.into());
                 let substs = generics.placeholder_subst(self.db);
-                let mut ty = self.db.impl_self_ty(impl_id).substitute(Interner, &substs);
+                let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+                let mut ty =
+                    self.db.impl_self_ty(impl_id).instantiate(interner, args).to_chalk(interner);
 
                 let Some(remaining_idx) = unresolved else {
                     drop(ctx);
@@ -1844,8 +1943,10 @@ impl<'db> InferenceContext<'db> {
                 };
                 let substs = path_ctx.substs_from_path_segment(it.into(), true, None, false);
                 drop(ctx);
-                let ty = self.db.ty(it.into());
-                let ty = self.insert_type_vars(ty.substitute(Interner, &substs));
+                let interner = DbInterner::conjure();
+                let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+                let ty = self.db.ty(it.into()).instantiate(interner, args).to_chalk(interner);
+                let ty = self.insert_type_vars(ty);
 
                 self.resolve_variant_on_alias(ty, unresolved, mod_path)
             }
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/infer/closure.rs b/src/tools/rust-analyzer/crates/hir-ty/src/infer/closure.rs
index 1d5d8dd13ed..4a57b2f3751 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/infer/closure.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/infer/closure.rs
@@ -318,7 +318,7 @@ impl<'db> InferenceContext<'db> {
                     _ = self
                         .table
                         .infer_ctxt
-                        .at(&ObligationCause::new(), self.table.param_env)
+                        .at(&ObligationCause::new(), self.table.trait_env.env)
                         .eq(DefineOpaqueTypes::Yes, inferred_fnptr_sig, generalized_fnptr_sig)
                         .map(|infer_ok| self.table.register_infer_ok(infer_ok));
 
@@ -703,7 +703,7 @@ impl<'db> InferenceContext<'db> {
                 let cause = ObligationCause::new();
                 let InferOk { value: (), obligations } = table
                     .infer_ctxt
-                    .at(&cause, table.param_env)
+                    .at(&cause, table.trait_env.env)
                     .eq(DefineOpaqueTypes::Yes, expected_ty, supplied_ty)?;
                 all_obligations.extend(obligations);
             }
@@ -711,7 +711,7 @@ impl<'db> InferenceContext<'db> {
             let supplied_output_ty = supplied_sig.output();
             let cause = ObligationCause::new();
             let InferOk { value: (), obligations } =
-                table.infer_ctxt.at(&cause, table.param_env).eq(
+                table.infer_ctxt.at(&cause, table.trait_env.env).eq(
                     DefineOpaqueTypes::Yes,
                     expected_sigs.liberated_sig.output(),
                     supplied_output_ty,
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/infer/coerce.rs b/src/tools/rust-analyzer/crates/hir-ty/src/infer/coerce.rs
index 7930d8b0ed6..62ce00a2e33 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/infer/coerce.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/infer/coerce.rs
@@ -144,7 +144,7 @@ impl<'a, 'b, 'db> Coerce<'a, 'b, 'db> {
     fn unify_raw(&mut self, a: Ty<'db>, b: Ty<'db>) -> InferResult<'db, Ty<'db>> {
         debug!("unify(a: {:?}, b: {:?}, use_lub: {})", a, b, self.use_lub);
         self.commit_if_ok(|this| {
-            let at = this.infer_ctxt().at(&this.cause, this.table.param_env);
+            let at = this.infer_ctxt().at(&this.cause, this.table.trait_env.env);
 
             let res = if this.use_lub {
                 at.lub(b, a)
@@ -210,9 +210,8 @@ impl<'a, 'b, 'db> Coerce<'a, 'b, 'db> {
         // Coercing from `!` to any type is allowed:
         if a.is_never() {
             // If we're coercing into an inference var, mark it as possibly diverging.
-            // FIXME: rustc does this differently.
-            if let TyKind::Infer(rustc_type_ir::TyVar(b)) = b.kind() {
-                self.table.set_diverging(b.as_u32().into(), chalk_ir::TyVariableKind::General);
+            if b.is_infer() {
+                self.table.set_diverging(b);
             }
 
             if self.coerce_never {
@@ -330,7 +329,7 @@ impl<'a, 'b, 'db> Coerce<'a, 'b, 'db> {
                     obligations.push(Obligation::new(
                         self.interner(),
                         self.cause.clone(),
-                        self.table.param_env,
+                        self.table.trait_env.env,
                         Binder::dummy(PredicateKind::Coerce(CoercePredicate {
                             a: source_ty,
                             b: target_ty,
@@ -718,7 +717,7 @@ impl<'a, 'b, 'db> Coerce<'a, 'b, 'db> {
         let mut queue: SmallVec<[PredicateObligation<'db>; 4]> = smallvec![Obligation::new(
             self.interner(),
             cause,
-            self.table.param_env,
+            self.table.trait_env.env,
             TraitRef::new(
                 self.interner(),
                 coerce_unsized_did.into(),
@@ -1114,8 +1113,12 @@ impl<'db> InferenceContext<'db> {
                         match self.table.commit_if_ok(|table| {
                             // We need to eagerly handle nested obligations due to lazy norm.
                             let mut ocx = ObligationCtxt::new(&table.infer_ctxt);
-                            let value =
-                                ocx.lub(&ObligationCause::new(), table.param_env, prev_ty, new_ty)?;
+                            let value = ocx.lub(
+                                &ObligationCause::new(),
+                                table.trait_env.env,
+                                prev_ty,
+                                new_ty,
+                            )?;
                             if ocx.select_where_possible().is_empty() {
                                 Ok(InferOk { value, obligations: ocx.into_pending_obligations() })
                             } else {
@@ -1158,7 +1161,7 @@ impl<'db> InferenceContext<'db> {
             let sig = self
                 .table
                 .infer_ctxt
-                .at(&ObligationCause::new(), self.table.param_env)
+                .at(&ObligationCause::new(), self.table.trait_env.env)
                 .lub(a_sig, b_sig)
                 .map(|ok| self.table.register_infer_ok(ok))?;
 
@@ -1248,7 +1251,7 @@ impl<'db> InferenceContext<'db> {
                         .commit_if_ok(|table| {
                             table
                                 .infer_ctxt
-                                .at(&ObligationCause::new(), table.param_env)
+                                .at(&ObligationCause::new(), table.trait_env.env)
                                 .lub(prev_ty, new_ty)
                         })
                         .unwrap_err())
@@ -1498,7 +1501,7 @@ impl<'db, 'exprs> CoerceMany<'db, 'exprs> {
             assert!(expression_ty.is_unit(), "if let hack without unit type");
             icx.table
                 .infer_ctxt
-                .at(cause, icx.table.param_env)
+                .at(cause, icx.table.trait_env.env)
                 .eq(
                     // needed for tests/ui/type-alias-impl-trait/issue-65679-inst-opaque-ty-from-val-twice.rs
                     DefineOpaqueTypes::Yes,
@@ -1564,9 +1567,9 @@ impl<'db, 'exprs> CoerceMany<'db, 'exprs> {
     }
 }
 
-pub fn could_coerce(
-    db: &dyn HirDatabase,
-    env: Arc<TraitEnvironment>,
+pub fn could_coerce<'db>(
+    db: &'db dyn HirDatabase,
+    env: Arc<TraitEnvironment<'db>>,
     tys: &crate::Canonical<(crate::Ty, crate::Ty)>,
 ) -> bool {
     coerce(db, env, tys).is_ok()
@@ -1574,7 +1577,7 @@ pub fn could_coerce(
 
 fn coerce<'db>(
     db: &'db dyn HirDatabase,
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'db>>,
     tys: &crate::Canonical<(crate::Ty, crate::Ty)>,
 ) -> Result<(Vec<Adjustment>, crate::Ty), TypeError<DbInterner<'db>>> {
     let mut table = InferenceTable::new(db, env);
@@ -1609,16 +1612,21 @@ fn coerce<'db>(
             chalk_ir::GenericArgData::Const(c) => c.inference_var(Interner),
         } == Some(iv))
     };
-    let fallback = |iv, kind, default, binder| match kind {
-        chalk_ir::VariableKind::Ty(_ty_kind) => find_var(iv)
-            .map_or(default, |i| crate::BoundVar::new(binder, i).to_ty(Interner).cast(Interner)),
-        chalk_ir::VariableKind::Lifetime => find_var(iv).map_or(default, |i| {
-            crate::BoundVar::new(binder, i).to_lifetime(Interner).cast(Interner)
-        }),
-        chalk_ir::VariableKind::Const(ty) => find_var(iv).map_or(default, |i| {
-            crate::BoundVar::new(binder, i).to_const(Interner, ty).cast(Interner)
-        }),
+    let fallback = |iv, kind, binder| match kind {
+        chalk_ir::VariableKind::Ty(_ty_kind) => find_var(iv).map_or_else(
+            || chalk_ir::TyKind::Error.intern(Interner).cast(Interner),
+            |i| crate::BoundVar::new(binder, i).to_ty(Interner).cast(Interner),
+        ),
+        chalk_ir::VariableKind::Lifetime => find_var(iv).map_or_else(
+            || crate::LifetimeData::Error.intern(Interner).cast(Interner),
+            |i| crate::BoundVar::new(binder, i).to_lifetime(Interner).cast(Interner),
+        ),
+        chalk_ir::VariableKind::Const(ty) => find_var(iv).map_or_else(
+            || crate::unknown_const(ty.clone()).cast(Interner),
+            |i| crate::BoundVar::new(binder, i).to_const(Interner, ty.clone()).cast(Interner),
+        ),
     };
     // FIXME also map the types in the adjustments
+    // FIXME: We don't fallback correctly since this is done on `InferenceContext` and we only have `InferenceTable`.
     Ok((adjustments, table.resolve_with_fallback(ty.to_chalk(table.interner), &fallback)))
 }
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/infer/expr.rs b/src/tools/rust-analyzer/crates/hir-ty/src/infer/expr.rs
index c5a51dfc4cf..ddf632c1c81 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/infer/expr.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/infer/expr.rs
@@ -23,13 +23,13 @@ use syntax::ast::RangeOp;
 use tracing::debug;
 
 use crate::autoderef::overloaded_deref_ty;
-use crate::next_solver::ErrorGuaranteed;
 use crate::next_solver::infer::DefineOpaqueTypes;
 use crate::next_solver::obligation_ctxt::ObligationCtxt;
+use crate::next_solver::{DbInterner, ErrorGuaranteed};
 use crate::{
-    Adjust, Adjustment, AdtId, AutoBorrow, Binders, CallableDefId, CallableSig, DeclContext,
-    DeclOrigin, IncorrectGenericsLenKind, Interner, LifetimeElisionKind, Rawness, Scalar,
-    Substitution, TraitEnvironment, TraitRef, Ty, TyBuilder, TyExt, TyKind, consteval,
+    Adjust, Adjustment, AdtId, AutoBorrow, CallableDefId, CallableSig, DeclContext, DeclOrigin,
+    IncorrectGenericsLenKind, Interner, LifetimeElisionKind, Rawness, Scalar, Substitution,
+    TraitEnvironment, TraitRef, Ty, TyBuilder, TyExt, TyKind, consteval,
     generics::generics,
     infer::{
         AllowTwoPhase, BreakableKind,
@@ -1481,7 +1481,10 @@ impl<'db> InferenceContext<'db> {
 
         self.write_method_resolution(tgt_expr, func, subst.clone());
 
-        let method_ty = self.db.value_ty(func.into()).unwrap().substitute(Interner, &subst);
+        let interner = DbInterner::new_with(self.db, None, None);
+        let args: crate::next_solver::GenericArgs<'_> = subst.to_nextsolver(interner);
+        let method_ty =
+            self.db.value_ty(func.into()).unwrap().instantiate(interner, args).to_chalk(interner);
         self.register_obligations_for_call(&method_ty);
 
         self.infer_expr_coerce(rhs, &Expectation::has_type(rhs_ty.clone()), ExprIsRead::Yes);
@@ -1662,7 +1665,6 @@ impl<'db> InferenceContext<'db> {
             });
         self.resolver.reset_to_guard(g);
         if let Some(prev_env) = prev_env {
-            self.table.param_env = prev_env.env.to_nextsolver(self.table.interner);
             self.table.trait_env = prev_env;
         }
 
@@ -1801,11 +1803,17 @@ impl<'db> InferenceContext<'db> {
                         self.write_expr_adj(receiver, adjustments.into_boxed_slice());
                         self.write_method_resolution(tgt_expr, func, substs.clone());
 
+                        let interner = DbInterner::new_with(self.db, None, None);
+                        let args: crate::next_solver::GenericArgs<'_> =
+                            substs.to_nextsolver(interner);
                         self.check_method_call(
                             tgt_expr,
                             &[],
-                            self.db.value_ty(func.into()).unwrap(),
-                            substs,
+                            self.db
+                                .value_ty(func.into())
+                                .unwrap()
+                                .instantiate(interner, args)
+                                .to_chalk(interner),
                             ty,
                             expected,
                         )
@@ -1964,11 +1972,16 @@ impl<'db> InferenceContext<'db> {
 
                 let substs = self.substs_for_method_call(tgt_expr, func.into(), generic_args);
                 self.write_method_resolution(tgt_expr, func, substs.clone());
+                let interner = DbInterner::new_with(self.db, None, None);
+                let gen_args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
                 self.check_method_call(
                     tgt_expr,
                     args,
-                    self.db.value_ty(func.into()).expect("we have a function def"),
-                    substs,
+                    self.db
+                        .value_ty(func.into())
+                        .expect("we have a function def")
+                        .instantiate(interner, gen_args)
+                        .to_chalk(interner),
                     ty,
                     expected,
                 )
@@ -2013,11 +2026,15 @@ impl<'db> InferenceContext<'db> {
                 let recovered = match assoc_func_with_same_name {
                     Some(f) => {
                         let substs = self.substs_for_method_call(tgt_expr, f.into(), generic_args);
+                        let interner = DbInterner::new_with(self.db, None, None);
+                        let args: crate::next_solver::GenericArgs<'_> =
+                            substs.to_nextsolver(interner);
                         let f = self
                             .db
                             .value_ty(f.into())
                             .expect("we have a function def")
-                            .substitute(Interner, &substs);
+                            .instantiate(interner, args)
+                            .to_chalk(interner);
                         let sig = f.callable_sig(self.db).expect("we have a function def");
                         Some((f, sig, true))
                     }
@@ -2057,12 +2074,10 @@ impl<'db> InferenceContext<'db> {
         &mut self,
         tgt_expr: ExprId,
         args: &[ExprId],
-        method_ty: Binders<Ty>,
-        substs: Substitution,
+        method_ty: Ty,
         receiver_ty: Ty,
         expected: &Expectation,
     ) -> Ty {
-        let method_ty = method_ty.substitute(Interner, &substs);
         self.register_obligations_for_call(&method_ty);
         let interner = self.table.interner;
         let ((formal_receiver_ty, param_tys), ret_ty, is_varargs) =
@@ -2132,7 +2147,7 @@ impl<'db> InferenceContext<'db> {
                         let origin = ObligationCause::new();
                         ocx.sup(
                             &origin,
-                            self.table.param_env,
+                            self.table.trait_env.env,
                             expected_output.to_nextsolver(interner),
                             formal_output,
                         )?;
@@ -2239,7 +2254,7 @@ impl<'db> InferenceContext<'db> {
             let formal_ty_error = this
                 .table
                 .infer_ctxt
-                .at(&ObligationCause::new(), this.table.param_env)
+                .at(&ObligationCause::new(), this.table.trait_env.env)
                 .eq(DefineOpaqueTypes::Yes, formal_input_ty, coerced_ty);
 
             // If neither check failed, the types are compatible
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/infer/fallback.rs b/src/tools/rust-analyzer/crates/hir-ty/src/infer/fallback.rs
new file mode 100644
index 00000000000..2022447ad43
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/infer/fallback.rs
@@ -0,0 +1,439 @@
+//! Fallback of infer vars to `!` and `i32`/`f64`.
+
+use intern::sym;
+use petgraph::{
+    Graph,
+    visit::{Dfs, Walker},
+};
+use rustc_hash::{FxBuildHasher, FxHashMap, FxHashSet};
+use rustc_type_ir::{
+    TyVid,
+    inherent::{IntoKind, Ty as _},
+};
+use tracing::debug;
+
+use crate::{
+    infer::InferenceContext,
+    next_solver::{CoercePredicate, PredicateKind, SubtypePredicate, Ty, TyKind},
+};
+
+#[derive(Copy, Clone)]
+pub(crate) enum DivergingFallbackBehavior {
+    /// Always fallback to `()` (aka "always spontaneous decay")
+    ToUnit,
+    /// Sometimes fallback to `!`, but mainly fallback to `()` so that most of the crates are not broken.
+    ContextDependent,
+    /// Always fallback to `!` (which should be equivalent to never falling back + not making
+    /// never-to-any coercions unless necessary)
+    ToNever,
+}
+
+impl<'db> InferenceContext<'db> {
+    pub(super) fn type_inference_fallback(&mut self) {
+        debug!(
+            "type-inference-fallback start obligations: {:#?}",
+            self.table.fulfillment_cx.pending_obligations()
+        );
+
+        // All type checking constraints were added, try to fallback unsolved variables.
+        self.table.select_obligations_where_possible();
+
+        debug!(
+            "type-inference-fallback post selection obligations: {:#?}",
+            self.table.fulfillment_cx.pending_obligations()
+        );
+
+        let fallback_occurred = self.fallback_types();
+
+        if !fallback_occurred {
+            return;
+        }
+
+        // We now see if we can make progress. This might cause us to
+        // unify inference variables for opaque types, since we may
+        // have unified some other type variables during the first
+        // phase of fallback. This means that we only replace
+        // inference variables with their underlying opaque types as a
+        // last resort.
+        //
+        // In code like this:
+        //
+        // ```rust
+        // type MyType = impl Copy;
+        // fn produce() -> MyType { true }
+        // fn bad_produce() -> MyType { panic!() }
+        // ```
+        //
+        // we want to unify the opaque inference variable in `bad_produce`
+        // with the diverging fallback for `panic!` (e.g. `()` or `!`).
+        // This will produce a nice error message about conflicting concrete
+        // types for `MyType`.
+        //
+        // If we had tried to fallback the opaque inference variable to `MyType`,
+        // we will generate a confusing type-check error that does not explicitly
+        // refer to opaque types.
+        self.table.select_obligations_where_possible();
+    }
+
+    fn diverging_fallback_behavior(&self) -> DivergingFallbackBehavior {
+        if self.krate().data(self.db).edition.at_least_2024() {
+            return DivergingFallbackBehavior::ToNever;
+        }
+
+        if self.resolver.def_map().is_unstable_feature_enabled(&sym::never_type_fallback) {
+            return DivergingFallbackBehavior::ContextDependent;
+        }
+
+        DivergingFallbackBehavior::ToUnit
+    }
+
+    fn fallback_types(&mut self) -> bool {
+        // Check if we have any unresolved variables. If not, no need for fallback.
+        let unresolved_variables = self.table.infer_ctxt.unresolved_variables();
+
+        if unresolved_variables.is_empty() {
+            return false;
+        }
+
+        let diverging_fallback_behavior = self.diverging_fallback_behavior();
+
+        let diverging_fallback =
+            self.calculate_diverging_fallback(&unresolved_variables, diverging_fallback_behavior);
+
+        // We do fallback in two passes, to try to generate
+        // better error messages.
+        // The first time, we do *not* replace opaque types.
+        let mut fallback_occurred = false;
+        for ty in unresolved_variables {
+            debug!("unsolved_variable = {:?}", ty);
+            fallback_occurred |= self.fallback_if_possible(ty, &diverging_fallback);
+        }
+
+        fallback_occurred
+    }
+
+    // Tries to apply a fallback to `ty` if it is an unsolved variable.
+    //
+    // - Unconstrained ints are replaced with `i32`.
+    //
+    // - Unconstrained floats are replaced with `f64`.
+    //
+    // - Non-numerics may get replaced with `()` or `!`, depending on
+    //   how they were categorized by `calculate_diverging_fallback`
+    //   (and the setting of `#![feature(never_type_fallback)]`).
+    //
+    // Fallback becomes very dubious if we have encountered
+    // type-checking errors. In that case, fallback to Error.
+    //
+    // Sets `FnCtxt::fallback_has_occurred` if fallback is performed
+    // during this call.
+    fn fallback_if_possible(
+        &mut self,
+        ty: Ty<'db>,
+        diverging_fallback: &FxHashMap<Ty<'db>, Ty<'db>>,
+    ) -> bool {
+        // Careful: we do NOT shallow-resolve `ty`. We know that `ty`
+        // is an unsolved variable, and we determine its fallback
+        // based solely on how it was created, not what other type
+        // variables it may have been unified with since then.
+        //
+        // The reason this matters is that other attempts at fallback
+        // may (in principle) conflict with this fallback, and we wish
+        // to generate a type error in that case. (However, this
+        // actually isn't true right now, because we're only using the
+        // builtin fallback rules. This would be true if we were using
+        // user-supplied fallbacks. But it's still useful to write the
+        // code to detect bugs.)
+        //
+        // (Note though that if we have a general type variable `?T`
+        // that is then unified with an integer type variable `?I`
+        // that ultimately never gets resolved to a special integral
+        // type, `?T` is not considered unsolved, but `?I` is. The
+        // same is true for float variables.)
+        let fallback = match ty.kind() {
+            TyKind::Infer(rustc_type_ir::IntVar(_)) => self.types.i32,
+            TyKind::Infer(rustc_type_ir::FloatVar(_)) => self.types.f64,
+            _ => match diverging_fallback.get(&ty) {
+                Some(&fallback_ty) => fallback_ty,
+                None => return false,
+            },
+        };
+        debug!("fallback_if_possible(ty={:?}): defaulting to `{:?}`", ty, fallback);
+
+        self.demand_eqtype(ty, fallback);
+        true
+    }
+
+    /// The "diverging fallback" system is rather complicated. This is
+    /// a result of our need to balance 'do the right thing' with
+    /// backwards compatibility.
+    ///
+    /// "Diverging" type variables are variables created when we
+    /// coerce a `!` type into an unbound type variable `?X`. If they
+    /// never wind up being constrained, the "right and natural" thing
+    /// is that `?X` should "fallback" to `!`. This means that e.g. an
+    /// expression like `Some(return)` will ultimately wind up with a
+    /// type like `Option<!>` (presuming it is not assigned or
+    /// constrained to have some other type).
+    ///
+    /// However, the fallback used to be `()` (before the `!` type was
+    /// added). Moreover, there are cases where the `!` type 'leaks
+    /// out' from dead code into type variables that affect live
+    /// code. The most common case is something like this:
+    ///
+    /// ```rust
+    /// # fn foo() -> i32 { 4 }
+    /// match foo() {
+    ///     22 => Default::default(), // call this type `?D`
+    ///     _ => return, // return has type `!`
+    /// } // call the type of this match `?M`
+    /// ```
+    ///
+    /// Here, coercing the type `!` into `?M` will create a diverging
+    /// type variable `?X` where `?X <: ?M`. We also have that `?D <:
+    /// ?M`. If `?M` winds up unconstrained, then `?X` will
+    /// fallback. If it falls back to `!`, then all the type variables
+    /// will wind up equal to `!` -- this includes the type `?D`
+    /// (since `!` doesn't implement `Default`, we wind up a "trait
+    /// not implemented" error in code like this). But since the
+    /// original fallback was `()`, this code used to compile with `?D
+    /// = ()`. This is somewhat surprising, since `Default::default()`
+    /// on its own would give an error because the types are
+    /// insufficiently constrained.
+    ///
+    /// Our solution to this dilemma is to modify diverging variables
+    /// so that they can *either* fallback to `!` (the default) or to
+    /// `()` (the backwards compatibility case). We decide which
+    /// fallback to use based on whether there is a coercion pattern
+    /// like this:
+    ///
+    /// ```ignore (not-rust)
+    /// ?Diverging -> ?V
+    /// ?NonDiverging -> ?V
+    /// ?V != ?NonDiverging
+    /// ```
+    ///
+    /// Here `?Diverging` represents some diverging type variable and
+    /// `?NonDiverging` represents some non-diverging type
+    /// variable. `?V` can be any type variable (diverging or not), so
+    /// long as it is not equal to `?NonDiverging`.
+    ///
+    /// Intuitively, what we are looking for is a case where a
+    /// "non-diverging" type variable (like `?M` in our example above)
+    /// is coerced *into* some variable `?V` that would otherwise
+    /// fallback to `!`. In that case, we make `?V` fallback to `!`,
+    /// along with anything that would flow into `?V`.
+    ///
+    /// The algorithm we use:
+    /// * Identify all variables that are coerced *into* by a
+    ///   diverging variable. Do this by iterating over each
+    ///   diverging, unsolved variable and finding all variables
+    ///   reachable from there. Call that set `D`.
+    /// * Walk over all unsolved, non-diverging variables, and find
+    ///   any variable that has an edge into `D`.
+    fn calculate_diverging_fallback(
+        &self,
+        unresolved_variables: &[Ty<'db>],
+        behavior: DivergingFallbackBehavior,
+    ) -> FxHashMap<Ty<'db>, Ty<'db>> {
+        debug!("calculate_diverging_fallback({:?})", unresolved_variables);
+
+        // Construct a coercion graph where an edge `A -> B` indicates
+        // a type variable is that is coerced
+        let coercion_graph = self.create_coercion_graph();
+
+        // Extract the unsolved type inference variable vids; note that some
+        // unsolved variables are integer/float variables and are excluded.
+        let unsolved_vids = unresolved_variables.iter().filter_map(|ty| ty.ty_vid());
+
+        // Compute the diverging root vids D -- that is, the root vid of
+        // those type variables that (a) are the target of a coercion from
+        // a `!` type and (b) have not yet been solved.
+        //
+        // These variables are the ones that are targets for fallback to
+        // either `!` or `()`.
+        let diverging_roots: FxHashSet<TyVid> = self
+            .table
+            .diverging_type_vars
+            .iter()
+            .map(|&ty| self.shallow_resolve(ty))
+            .filter_map(|ty| ty.ty_vid())
+            .map(|vid| self.table.infer_ctxt.root_var(vid))
+            .collect();
+        debug!(
+            "calculate_diverging_fallback: diverging_type_vars={:?}",
+            self.table.diverging_type_vars
+        );
+        debug!("calculate_diverging_fallback: diverging_roots={:?}", diverging_roots);
+
+        // Find all type variables that are reachable from a diverging
+        // type variable. These will typically default to `!`, unless
+        // we find later that they are *also* reachable from some
+        // other type variable outside this set.
+        let mut roots_reachable_from_diverging = Dfs::empty(&coercion_graph);
+        let mut diverging_vids = vec![];
+        let mut non_diverging_vids = vec![];
+        for unsolved_vid in unsolved_vids {
+            let root_vid = self.table.infer_ctxt.root_var(unsolved_vid);
+            debug!(
+                "calculate_diverging_fallback: unsolved_vid={:?} root_vid={:?} diverges={:?}",
+                unsolved_vid,
+                root_vid,
+                diverging_roots.contains(&root_vid),
+            );
+            if diverging_roots.contains(&root_vid) {
+                diverging_vids.push(unsolved_vid);
+                roots_reachable_from_diverging.move_to(root_vid.as_u32().into());
+
+                // drain the iterator to visit all nodes reachable from this node
+                while roots_reachable_from_diverging.next(&coercion_graph).is_some() {}
+            } else {
+                non_diverging_vids.push(unsolved_vid);
+            }
+        }
+
+        debug!(
+            "calculate_diverging_fallback: roots_reachable_from_diverging={:?}",
+            roots_reachable_from_diverging,
+        );
+
+        // Find all type variables N0 that are not reachable from a
+        // diverging variable, and then compute the set reachable from
+        // N0, which we call N. These are the *non-diverging* type
+        // variables. (Note that this set consists of "root variables".)
+        let mut roots_reachable_from_non_diverging = Dfs::empty(&coercion_graph);
+        for &non_diverging_vid in &non_diverging_vids {
+            let root_vid = self.table.infer_ctxt.root_var(non_diverging_vid);
+            if roots_reachable_from_diverging.discovered.contains(root_vid.as_usize()) {
+                continue;
+            }
+            roots_reachable_from_non_diverging.move_to(root_vid.as_u32().into());
+            while roots_reachable_from_non_diverging.next(&coercion_graph).is_some() {}
+        }
+        debug!(
+            "calculate_diverging_fallback: roots_reachable_from_non_diverging={:?}",
+            roots_reachable_from_non_diverging,
+        );
+
+        debug!("obligations: {:#?}", self.table.fulfillment_cx.pending_obligations());
+
+        // For each diverging variable, figure out whether it can
+        // reach a member of N. If so, it falls back to `()`. Else
+        // `!`.
+        let mut diverging_fallback =
+            FxHashMap::with_capacity_and_hasher(diverging_vids.len(), FxBuildHasher);
+
+        for &diverging_vid in &diverging_vids {
+            let diverging_ty = Ty::new_var(self.table.interner, diverging_vid);
+            let root_vid = self.table.infer_ctxt.root_var(diverging_vid);
+            let can_reach_non_diverging = Dfs::new(&coercion_graph, root_vid.as_u32().into())
+                .iter(&coercion_graph)
+                .any(|n| roots_reachable_from_non_diverging.discovered.contains(n.index()));
+
+            let mut fallback_to = |ty| {
+                diverging_fallback.insert(diverging_ty, ty);
+            };
+
+            match behavior {
+                DivergingFallbackBehavior::ToUnit => {
+                    debug!("fallback to () - legacy: {:?}", diverging_vid);
+                    fallback_to(self.types.unit);
+                }
+                DivergingFallbackBehavior::ContextDependent => {
+                    // FIXME: rustc does the following, but given this is only relevant when the unstable
+                    // `never_type_fallback` feature is active, I chose to not port this.
+                    // if found_infer_var_info.self_in_trait && found_infer_var_info.output {
+                    //     // This case falls back to () to ensure that the code pattern in
+                    //     // tests/ui/never_type/fallback-closure-ret.rs continues to
+                    //     // compile when never_type_fallback is enabled.
+                    //     //
+                    //     // This rule is not readily explainable from first principles,
+                    //     // but is rather intended as a patchwork fix to ensure code
+                    //     // which compiles before the stabilization of never type
+                    //     // fallback continues to work.
+                    //     //
+                    //     // Typically this pattern is encountered in a function taking a
+                    //     // closure as a parameter, where the return type of that closure
+                    //     // (checked by `relationship.output`) is expected to implement
+                    //     // some trait (checked by `relationship.self_in_trait`). This
+                    //     // can come up in non-closure cases too, so we do not limit this
+                    //     // rule to specifically `FnOnce`.
+                    //     //
+                    //     // When the closure's body is something like `panic!()`, the
+                    //     // return type would normally be inferred to `!`. However, it
+                    //     // needs to fall back to `()` in order to still compile, as the
+                    //     // trait is specifically implemented for `()` but not `!`.
+                    //     //
+                    //     // For details on the requirements for these relationships to be
+                    //     // set, see the relationship finding module in
+                    //     // compiler/rustc_trait_selection/src/traits/relationships.rs.
+                    //     debug!("fallback to () - found trait and projection: {:?}", diverging_vid);
+                    //     fallback_to(self.types.unit);
+                    // }
+                    if can_reach_non_diverging {
+                        debug!("fallback to () - reached non-diverging: {:?}", diverging_vid);
+                        fallback_to(self.types.unit);
+                    } else {
+                        debug!("fallback to ! - all diverging: {:?}", diverging_vid);
+                        fallback_to(self.types.never);
+                    }
+                }
+                DivergingFallbackBehavior::ToNever => {
+                    debug!(
+                        "fallback to ! - `rustc_never_type_mode = \"fallback_to_never\")`: {:?}",
+                        diverging_vid
+                    );
+                    fallback_to(self.types.never);
+                }
+            }
+        }
+
+        diverging_fallback
+    }
+
+    /// Returns a graph whose nodes are (unresolved) inference variables and where
+    /// an edge `?A -> ?B` indicates that the variable `?A` is coerced to `?B`.
+    fn create_coercion_graph(&self) -> Graph<(), ()> {
+        let pending_obligations = self.table.fulfillment_cx.pending_obligations();
+        let pending_obligations_len = pending_obligations.len();
+        debug!("create_coercion_graph: pending_obligations={:?}", pending_obligations);
+        let coercion_edges = pending_obligations
+            .into_iter()
+            .filter_map(|obligation| {
+                // The predicates we are looking for look like `Coerce(?A -> ?B)`.
+                // They will have no bound variables.
+                obligation.predicate.kind().no_bound_vars()
+            })
+            .filter_map(|atom| {
+                // We consider both subtyping and coercion to imply 'flow' from
+                // some position in the code `a` to a different position `b`.
+                // This is then used to determine which variables interact with
+                // live code, and as such must fall back to `()` to preserve
+                // soundness.
+                //
+                // In practice currently the two ways that this happens is
+                // coercion and subtyping.
+                let (a, b) = match atom {
+                    PredicateKind::Coerce(CoercePredicate { a, b }) => (a, b),
+                    PredicateKind::Subtype(SubtypePredicate { a_is_expected: _, a, b }) => (a, b),
+                    _ => return None,
+                };
+
+                let a_vid = self.root_vid(a)?;
+                let b_vid = self.root_vid(b)?;
+                Some((a_vid.as_u32(), b_vid.as_u32()))
+            });
+        let num_ty_vars = self.table.infer_ctxt.num_ty_vars();
+        let mut graph = Graph::with_capacity(num_ty_vars, pending_obligations_len);
+        for _ in 0..num_ty_vars {
+            graph.add_node(());
+        }
+        graph.extend_with_edges(coercion_edges);
+        graph
+    }
+
+    /// If `ty` is an unresolved type variable, returns its root vid.
+    fn root_vid(&self, ty: Ty<'db>) -> Option<TyVid> {
+        Some(self.table.infer_ctxt.root_var(self.shallow_resolve(ty).ty_vid()?))
+    }
+}
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/infer/path.rs b/src/tools/rust-analyzer/crates/hir-ty/src/infer/path.rs
index 80f7324e58b..733f3c27880 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/infer/path.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/infer/path.rs
@@ -17,7 +17,10 @@ use crate::{
     generics::generics,
     infer::diagnostics::InferenceTyLoweringContext as TyLoweringContext,
     method_resolution::{self, VisibleFromModule},
-    next_solver::mapping::ChalkToNextSolver,
+    next_solver::{
+        DbInterner,
+        mapping::{ChalkToNextSolver, NextSolverToChalk},
+    },
     to_chalk_trait_id,
 };
 
@@ -36,7 +39,9 @@ impl<'db> InferenceContext<'db> {
 
         self.add_required_obligations_for_value_path(generic_def, &substs);
 
-        let ty = self.db.value_ty(value_def)?.substitute(Interner, &substs);
+        let interner = DbInterner::new_with(self.db, None, None);
+        let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+        let ty = self.db.value_ty(value_def)?.instantiate(interner, args).to_chalk(interner);
         let ty = self.process_remote_user_written_ty(ty);
         Some(ty)
     }
@@ -69,8 +74,11 @@ impl<'db> InferenceContext<'db> {
             }
             ValueNs::ImplSelf(impl_id) => {
                 let generics = crate::generics::generics(self.db, impl_id.into());
+                let interner = DbInterner::new_with(self.db, None, None);
                 let substs = generics.placeholder_subst(self.db);
-                let ty = self.db.impl_self_ty(impl_id).substitute(Interner, &substs);
+                let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+                let ty =
+                    self.db.impl_self_ty(impl_id).instantiate(interner, args).to_chalk(interner);
                 return if let Some((AdtId::StructId(struct_id), substs)) = ty.as_adt() {
                     Some(ValuePathResolution::GenericDef(
                         struct_id.into(),
@@ -89,9 +97,9 @@ impl<'db> InferenceContext<'db> {
 
         let generic_def = value_def.to_generic_def_id(self.db);
         if let GenericDefId::StaticId(_) = generic_def {
+            let interner = DbInterner::new_with(self.db, None, None);
             // `Static` is the kind of item that can never be generic currently. We can just skip the binders to get its type.
-            let (ty, binders) = self.db.value_ty(value_def)?.into_value_and_skipped_binders();
-            stdx::always!(binders.is_empty(Interner), "non-empty binders for non-generic def",);
+            let ty = self.db.value_ty(value_def)?.skip_binder().to_chalk(interner);
             return Some(ValuePathResolution::NonGeneric(ty));
         };
 
@@ -354,10 +362,13 @@ impl<'db> InferenceContext<'db> {
         };
         let substs = match container {
             ItemContainerId::ImplId(impl_id) => {
+                let interner = DbInterner::new_with(self.db, None, None);
                 let impl_substs = TyBuilder::subst_for_def(self.db, impl_id, None)
                     .fill_with_inference_vars(&mut self.table)
                     .build();
-                let impl_self_ty = self.db.impl_self_ty(impl_id).substitute(Interner, &impl_substs);
+                let args: crate::next_solver::GenericArgs<'_> = impl_substs.to_nextsolver(interner);
+                let impl_self_ty =
+                    self.db.impl_self_ty(impl_id).instantiate(interner, args).to_chalk(interner);
                 self.unify(&impl_self_ty, &ty);
                 impl_substs
             }
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/infer/unify.rs b/src/tools/rust-analyzer/crates/hir-ty/src/infer/unify.rs
index 1687857ae1a..108cf5b1a2b 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/infer/unify.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/infer/unify.rs
@@ -3,47 +3,42 @@
 use std::fmt;
 
 use chalk_ir::{
-    CanonicalVarKind, FloatTy, IntTy, TyVariableKind, cast::Cast, fold::TypeFoldable,
-    interner::HasInterner,
+    CanonicalVarKind, TyVariableKind, cast::Cast, fold::TypeFoldable, interner::HasInterner,
 };
 use either::Either;
 use hir_def::{AdtId, lang_item::LangItem};
 use hir_expand::name::Name;
 use intern::sym;
 use rustc_hash::{FxHashMap, FxHashSet};
-use rustc_type_ir::inherent::Ty as _;
 use rustc_type_ir::{
-    FloatVid, IntVid, TyVid, TypeVisitableExt,
-    inherent::{IntoKind, Span, Term as _},
+    TyVid, TypeVisitableExt, UpcastFrom,
+    inherent::{IntoKind, Span, Term as _, Ty as _},
     relate::{Relate, solver_relating::RelateExt},
-    solve::{Certainty, GoalSource, NoSolution},
+    solve::{Certainty, GoalSource},
 };
 use smallvec::SmallVec;
 use triomphe::Arc;
 
 use super::{InferResult, InferenceContext, TypeError};
-use crate::next_solver::ErrorGuaranteed;
 use crate::{
     AliasTy, BoundVar, Canonical, Const, ConstValue, DebruijnIndex, GenericArg, GenericArgData,
-    Goal, GoalData, InEnvironment, InferenceVar, Interner, Lifetime, OpaqueTyId, ParamKind,
-    ProjectionTy, Scalar, Substitution, TraitEnvironment, TraitRef, Ty, TyBuilder, TyExt, TyKind,
-    VariableKind, WhereClause,
+    InferenceVar, Interner, Lifetime, OpaqueTyId, ProjectionTy, Substitution, TraitEnvironment, Ty,
+    TyExt, TyKind, VariableKind,
     consteval::unknown_const,
     db::HirDatabase,
     fold_generic_args, fold_tys_and_consts,
-    next_solver::infer::InferOk,
     next_solver::{
-        self, ClauseKind, DbInterner, ParamEnv, Predicate, PredicateKind, SolverDefIds, Term,
+        self, ClauseKind, DbInterner, ErrorGuaranteed, Predicate, PredicateKind, SolverDefIds,
+        Term, TraitRef,
         fulfill::FulfillmentCtxt,
         infer::{
-            DbInternerInferExt, InferCtxt,
+            DbInternerInferExt, InferCtxt, InferOk,
             snapshot::CombinedSnapshot,
             traits::{Obligation, ObligationCause},
         },
         inspect::{InspectConfig, InspectGoal, ProofTreeVisitor},
         mapping::{ChalkToNextSolver, NextSolverToChalk},
     },
-    to_chalk_trait_id,
     traits::{
         FnTrait, NextTraitSolveResult, next_trait_solve_canonical_in_ctxt, next_trait_solve_in_ctxt,
     },
@@ -125,7 +120,7 @@ impl<'a, 'db> ProofTreeVisitor<'db> for NestedObligationsForSelfTy<'a, 'db> {
 /// unresolved goal `T = U`.
 pub fn could_unify(
     db: &dyn HirDatabase,
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'_>>,
     tys: &Canonical<(Ty, Ty)>,
 ) -> bool {
     unify(db, env, tys).is_some()
@@ -137,7 +132,7 @@ pub fn could_unify(
 /// them. For example `Option<T>` and `Option<U>` do not unify as we cannot show that `T = U`
 pub fn could_unify_deeply(
     db: &dyn HirDatabase,
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'_>>,
     tys: &Canonical<(Ty, Ty)>,
 ) -> bool {
     let mut table = InferenceTable::new(db, env);
@@ -147,7 +142,6 @@ pub fn could_unify_deeply(
     let ty1_with_vars = table.normalize_associated_types_in(ty1_with_vars);
     let ty2_with_vars = table.normalize_associated_types_in(ty2_with_vars);
     table.select_obligations_where_possible();
-    table.propagate_diverging_flag();
     let ty1_with_vars = table.resolve_completely(ty1_with_vars);
     let ty2_with_vars = table.resolve_completely(ty2_with_vars);
     table.unify_deeply(&ty1_with_vars, &ty2_with_vars)
@@ -155,7 +149,7 @@ pub fn could_unify_deeply(
 
 pub(crate) fn unify(
     db: &dyn HirDatabase,
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'_>>,
     tys: &Canonical<(Ty, Ty)>,
 ) -> Option<Substitution> {
     let mut table = InferenceTable::new(db, env);
@@ -174,13 +168,19 @@ pub(crate) fn unify(
             GenericArgData::Const(c) => c.inference_var(Interner),
         } == Some(iv))
     };
-    let fallback = |iv, kind, default, binder| match kind {
-        chalk_ir::VariableKind::Ty(_ty_kind) => find_var(iv)
-            .map_or(default, |i| BoundVar::new(binder, i).to_ty(Interner).cast(Interner)),
-        chalk_ir::VariableKind::Lifetime => find_var(iv)
-            .map_or(default, |i| BoundVar::new(binder, i).to_lifetime(Interner).cast(Interner)),
-        chalk_ir::VariableKind::Const(ty) => find_var(iv)
-            .map_or(default, |i| BoundVar::new(binder, i).to_const(Interner, ty).cast(Interner)),
+    let fallback = |iv, kind, binder| match kind {
+        chalk_ir::VariableKind::Ty(_ty_kind) => find_var(iv).map_or_else(
+            || TyKind::Error.intern(Interner).cast(Interner),
+            |i| BoundVar::new(binder, i).to_ty(Interner).cast(Interner),
+        ),
+        chalk_ir::VariableKind::Lifetime => find_var(iv).map_or_else(
+            || crate::error_lifetime().cast(Interner),
+            |i| BoundVar::new(binder, i).to_lifetime(Interner).cast(Interner),
+        ),
+        chalk_ir::VariableKind::Const(ty) => find_var(iv).map_or_else(
+            || crate::unknown_const(ty.clone()).cast(Interner),
+            |i| BoundVar::new(binder, i).to_const(Interner, ty.clone()).cast(Interner),
+        ),
     };
     Some(Substitution::from_iter(
         Interner,
@@ -216,22 +216,20 @@ bitflags::bitflags! {
 pub(crate) struct InferenceTable<'db> {
     pub(crate) db: &'db dyn HirDatabase,
     pub(crate) interner: DbInterner<'db>,
-    pub(crate) trait_env: Arc<TraitEnvironment>,
-    pub(crate) param_env: ParamEnv<'db>,
+    pub(crate) trait_env: Arc<TraitEnvironment<'db>>,
     pub(crate) tait_coercion_table: Option<FxHashMap<OpaqueTyId, Ty>>,
     pub(crate) infer_ctxt: InferCtxt<'db>,
-    diverging_tys: FxHashSet<Ty>,
     pub(super) fulfillment_cx: FulfillmentCtxt<'db>,
+    pub(super) diverging_type_vars: FxHashSet<crate::next_solver::Ty<'db>>,
 }
 
 pub(crate) struct InferenceTableSnapshot<'db> {
     ctxt_snapshot: CombinedSnapshot,
     obligations: FulfillmentCtxt<'db>,
-    diverging_tys: FxHashSet<Ty>,
 }
 
 impl<'db> InferenceTable<'db> {
-    pub(crate) fn new(db: &'db dyn HirDatabase, trait_env: Arc<TraitEnvironment>) -> Self {
+    pub(crate) fn new(db: &'db dyn HirDatabase, trait_env: Arc<TraitEnvironment<'db>>) -> Self {
         let interner = DbInterner::new_with(db, Some(trait_env.krate), trait_env.block);
         let infer_ctxt = interner.infer_ctxt().build(rustc_type_ir::TypingMode::Analysis {
             defining_opaque_types_and_generators: SolverDefIds::new_from_iter(interner, []),
@@ -239,12 +237,11 @@ impl<'db> InferenceTable<'db> {
         InferenceTable {
             db,
             interner,
-            param_env: trait_env.env.to_nextsolver(interner),
             trait_env,
             tait_coercion_table: None,
             fulfillment_cx: FulfillmentCtxt::new(&infer_ctxt),
             infer_ctxt,
-            diverging_tys: FxHashSet::default(),
+            diverging_type_vars: FxHashSet::default(),
         }
     }
 
@@ -327,74 +324,8 @@ impl<'db> InferenceTable<'db> {
         }
     }
 
-    /// Chalk doesn't know about the `diverging` flag, so when it unifies two
-    /// type variables of which one is diverging, the chosen root might not be
-    /// diverging and we have no way of marking it as such at that time. This
-    /// function goes through all type variables and make sure their root is
-    /// marked as diverging if necessary, so that resolving them gives the right
-    /// result.
-    pub(super) fn propagate_diverging_flag(&mut self) {
-        let mut new_tys = FxHashSet::default();
-        for ty in self.diverging_tys.iter() {
-            match ty.kind(Interner) {
-                TyKind::InferenceVar(var, kind) => match kind {
-                    TyVariableKind::General => {
-                        let root = InferenceVar::from(
-                            self.infer_ctxt.root_var(TyVid::from_u32(var.index())).as_u32(),
-                        );
-                        if root.index() != var.index() {
-                            new_tys.insert(TyKind::InferenceVar(root, *kind).intern(Interner));
-                        }
-                    }
-                    TyVariableKind::Integer => {
-                        let root = InferenceVar::from(
-                            self.infer_ctxt
-                                .inner
-                                .borrow_mut()
-                                .int_unification_table()
-                                .find(IntVid::from_usize(var.index() as usize))
-                                .as_u32(),
-                        );
-                        if root.index() != var.index() {
-                            new_tys.insert(TyKind::InferenceVar(root, *kind).intern(Interner));
-                        }
-                    }
-                    TyVariableKind::Float => {
-                        let root = InferenceVar::from(
-                            self.infer_ctxt
-                                .inner
-                                .borrow_mut()
-                                .float_unification_table()
-                                .find(FloatVid::from_usize(var.index() as usize))
-                                .as_u32(),
-                        );
-                        if root.index() != var.index() {
-                            new_tys.insert(TyKind::InferenceVar(root, *kind).intern(Interner));
-                        }
-                    }
-                },
-                _ => {}
-            }
-        }
-        self.diverging_tys.extend(new_tys);
-    }
-
-    pub(super) fn set_diverging(&mut self, iv: InferenceVar, kind: TyVariableKind) {
-        self.diverging_tys.insert(TyKind::InferenceVar(iv, kind).intern(Interner));
-    }
-
-    fn fallback_value(&self, iv: InferenceVar, kind: TyVariableKind) -> Ty {
-        let is_diverging =
-            self.diverging_tys.contains(&TyKind::InferenceVar(iv, kind).intern(Interner));
-        if is_diverging {
-            return TyKind::Never.intern(Interner);
-        }
-        match kind {
-            TyVariableKind::General => TyKind::Error,
-            TyVariableKind::Integer => TyKind::Scalar(Scalar::Int(IntTy::I32)),
-            TyVariableKind::Float => TyKind::Scalar(Scalar::Float(FloatTy::F64)),
-        }
-        .intern(Interner)
+    pub(super) fn set_diverging(&mut self, ty: crate::next_solver::Ty<'db>) {
+        self.diverging_type_vars.insert(ty);
     }
 
     pub(crate) fn canonicalize<T>(&mut self, t: T) -> rustc_type_ir::Canonical<DbInterner<'db>, T>
@@ -430,7 +361,7 @@ impl<'db> InferenceTable<'db> {
     {
         let ty = self.resolve_vars_with_obligations(ty);
         self.infer_ctxt
-            .at(&ObligationCause::new(), self.param_env)
+            .at(&ObligationCause::new(), self.trait_env.env)
             .deeply_normalize(ty.clone())
             .unwrap_or(ty)
     }
@@ -535,7 +466,7 @@ impl<'db> InferenceTable<'db> {
 
         let ty = var.to_ty(Interner, kind);
         if diverging {
-            self.diverging_tys.insert(ty.clone());
+            self.diverging_type_vars.insert(ty.to_nextsolver(self.interner));
         }
         ty
     }
@@ -579,7 +510,7 @@ impl<'db> InferenceTable<'db> {
     pub(crate) fn resolve_with_fallback<T>(
         &mut self,
         t: T,
-        fallback: &dyn Fn(InferenceVar, VariableKind, GenericArg, DebruijnIndex) -> GenericArg,
+        fallback: &dyn Fn(InferenceVar, VariableKind, DebruijnIndex) -> GenericArg,
     ) -> T
     where
         T: HasInterner<Interner = Interner> + TypeFoldable<Interner>,
@@ -621,7 +552,7 @@ impl<'db> InferenceTable<'db> {
     fn resolve_with_fallback_inner<T>(
         &mut self,
         t: T,
-        fallback: &dyn Fn(InferenceVar, VariableKind, GenericArg, DebruijnIndex) -> GenericArg,
+        fallback: &dyn Fn(InferenceVar, VariableKind, DebruijnIndex) -> GenericArg,
     ) -> T
     where
         T: HasInterner<Interner = Interner> + TypeFoldable<Interner>,
@@ -638,53 +569,15 @@ impl<'db> InferenceTable<'db> {
         T: HasInterner<Interner = Interner> + TypeFoldable<Interner> + ChalkToNextSolver<'db, U>,
         U: NextSolverToChalk<'db, T> + rustc_type_ir::TypeFoldable<DbInterner<'db>>,
     {
-        let t = self.resolve_with_fallback(t, &|_, _, d, _| d);
-        let t = self.normalize_associated_types_in(t);
-        // let t = self.resolve_opaque_tys_in(t);
-        // Resolve again, because maybe normalization inserted infer vars.
-        self.resolve_with_fallback(t, &|_, _, d, _| d)
-    }
+        let value = t.to_nextsolver(self.interner);
+        let value = self.infer_ctxt.resolve_vars_if_possible(value);
 
-    /// Apply a fallback to unresolved scalar types. Integer type variables and float type
-    /// variables are replaced with i32 and f64, respectively.
-    ///
-    /// This method is only intended to be called just before returning inference results (i.e. in
-    /// `InferenceContext::resolve_all()`).
-    ///
-    /// FIXME: This method currently doesn't apply fallback to unconstrained general type variables
-    /// whereas rustc replaces them with `()` or `!`.
-    pub(super) fn fallback_if_possible(&mut self) {
-        let int_fallback = TyKind::Scalar(Scalar::Int(IntTy::I32)).intern(Interner);
-        let float_fallback = TyKind::Scalar(Scalar::Float(FloatTy::F64)).intern(Interner);
-
-        let int_vars = self.infer_ctxt.inner.borrow_mut().int_unification_table().len();
-        for v in 0..int_vars {
-            let var = InferenceVar::from(v as u32).to_ty(Interner, TyVariableKind::Integer);
-            let maybe_resolved = self.resolve_ty_shallow(&var);
-            if let TyKind::InferenceVar(_, kind) = maybe_resolved.kind(Interner) {
-                // I don't think we can ever unify these vars with float vars, but keep this here for now
-                let fallback = match kind {
-                    TyVariableKind::Integer => &int_fallback,
-                    TyVariableKind::Float => &float_fallback,
-                    TyVariableKind::General => unreachable!(),
-                };
-                self.unify(&var, fallback);
-            }
-        }
-        let float_vars = self.infer_ctxt.inner.borrow_mut().float_unification_table().len();
-        for v in 0..float_vars {
-            let var = InferenceVar::from(v as u32).to_ty(Interner, TyVariableKind::Float);
-            let maybe_resolved = self.resolve_ty_shallow(&var);
-            if let TyKind::InferenceVar(_, kind) = maybe_resolved.kind(Interner) {
-                // I don't think we can ever unify these vars with float vars, but keep this here for now
-                let fallback = match kind {
-                    TyVariableKind::Integer => &int_fallback,
-                    TyVariableKind::Float => &float_fallback,
-                    TyVariableKind::General => unreachable!(),
-                };
-                self.unify(&var, fallback);
-            }
-        }
+        let mut goals = vec![];
+        let value = value.fold_with(&mut resolve_completely::Resolver::new(self, true, &mut goals));
+
+        // FIXME(next-solver): Handle `goals`.
+
+        value.to_chalk(self.interner)
     }
 
     /// Unify two relatable values (e.g. `Ty`) and register new trait goals that arise from that.
@@ -745,7 +638,7 @@ impl<'db> InferenceTable<'db> {
     ) -> InferResult<'db, ()> {
         let variance = rustc_type_ir::Variance::Invariant;
         let span = crate::next_solver::Span::dummy();
-        match self.infer_ctxt.relate(self.param_env, lhs, variance, rhs, span) {
+        match self.infer_ctxt.relate(self.trait_env.env, lhs, variance, rhs, span) {
             Ok(goals) => Ok(crate::infer::InferOk { goals, value: () }),
             Err(_) => Err(TypeError),
         }
@@ -786,7 +679,7 @@ impl<'db> InferenceTable<'db> {
     }
 
     pub(crate) fn structurally_resolve_type(&mut self, ty: &Ty) -> Ty {
-        if let TyKind::Alias(..) = ty.kind(Interner) {
+        if let TyKind::Alias(chalk_ir::AliasTy::Projection(..)) = ty.kind(Interner) {
             self.structurally_normalize_ty(ty)
         } else {
             self.resolve_vars_with_obligations(ty.to_nextsolver(self.interner))
@@ -802,7 +695,7 @@ impl<'db> InferenceTable<'db> {
 
     fn structurally_normalize_term(&mut self, term: Term<'db>) -> Term<'db> {
         self.infer_ctxt
-            .at(&ObligationCause::new(), self.param_env)
+            .at(&ObligationCause::new(), self.trait_env.env)
             .structurally_normalize_term(term, &mut self.fulfillment_cx)
             .unwrap_or(term)
     }
@@ -822,7 +715,7 @@ impl<'db> InferenceTable<'db> {
             // in a reentrant borrow, causing an ICE.
             let result = self
                 .infer_ctxt
-                .at(&ObligationCause::misc(), self.param_env)
+                .at(&ObligationCause::misc(), self.trait_env.env)
                 .structurally_normalize_ty(ty, &mut self.fulfillment_cx);
             match result {
                 Ok(normalized_ty) => normalized_ty,
@@ -835,15 +728,13 @@ impl<'db> InferenceTable<'db> {
 
     pub(crate) fn snapshot(&mut self) -> InferenceTableSnapshot<'db> {
         let ctxt_snapshot = self.infer_ctxt.start_snapshot();
-        let diverging_tys = self.diverging_tys.clone();
         let obligations = self.fulfillment_cx.clone();
-        InferenceTableSnapshot { ctxt_snapshot, diverging_tys, obligations }
+        InferenceTableSnapshot { ctxt_snapshot, obligations }
     }
 
     #[tracing::instrument(skip_all)]
     pub(crate) fn rollback_to(&mut self, snapshot: InferenceTableSnapshot<'db>) {
         self.infer_ctxt.rollback_to(snapshot.ctxt_snapshot);
-        self.diverging_tys = snapshot.diverging_tys;
         self.fulfillment_cx = snapshot.obligations;
     }
 
@@ -877,26 +768,15 @@ impl<'db> InferenceTable<'db> {
     /// whether a trait *might* be implemented before deciding to 'lock in' the
     /// choice (during e.g. method resolution or deref).
     #[tracing::instrument(level = "debug", skip(self))]
-    pub(crate) fn try_obligation(&mut self, goal: Goal) -> NextTraitSolveResult {
-        let in_env = InEnvironment::new(&self.trait_env.env, goal);
-        let canonicalized = self.canonicalize(in_env.to_nextsolver(self.interner));
+    pub(crate) fn try_obligation(&mut self, predicate: Predicate<'db>) -> NextTraitSolveResult {
+        let goal = next_solver::Goal { param_env: self.trait_env.env, predicate };
+        let canonicalized = self.canonicalize(goal);
 
         next_trait_solve_canonical_in_ctxt(&self.infer_ctxt, canonicalized)
     }
 
-    #[tracing::instrument(level = "debug", skip(self))]
-    pub(crate) fn solve_obligation(&mut self, goal: Goal) -> Result<Certainty, NoSolution> {
-        let goal = InEnvironment::new(&self.trait_env.env, goal);
-        let goal = goal.to_nextsolver(self.interner);
-        let result = next_trait_solve_in_ctxt(&self.infer_ctxt, goal);
-        result.map(|m| m.1)
-    }
-
     pub(crate) fn register_obligation(&mut self, predicate: Predicate<'db>) {
-        let goal = next_solver::Goal {
-            param_env: self.trait_env.env.to_nextsolver(self.interner),
-            predicate,
-        };
+        let goal = next_solver::Goal { param_env: self.trait_env.env, predicate };
         self.register_obligation_in_env(goal)
     }
 
@@ -984,7 +864,7 @@ impl<'db> InferenceTable<'db> {
         &mut self,
         ty: &Ty,
         num_args: usize,
-    ) -> Option<(FnTrait, Vec<crate::next_solver::Ty<'db>>, crate::next_solver::Ty<'db>)> {
+    ) -> Option<(FnTrait, Vec<next_solver::Ty<'db>>, next_solver::Ty<'db>)> {
         for (fn_trait_name, output_assoc_name, subtraits) in [
             (FnTrait::FnOnce, sym::Output, &[FnTrait::Fn, FnTrait::FnMut][..]),
             (FnTrait::AsyncFnMut, sym::CallRefFuture, &[FnTrait::AsyncFn]),
@@ -997,42 +877,34 @@ impl<'db> InferenceTable<'db> {
                 trait_data.associated_type_by_name(&Name::new_symbol_root(output_assoc_name))?;
 
             let mut arg_tys = Vec::with_capacity(num_args);
-            let arg_ty = TyBuilder::tuple(num_args)
-                .fill(|it| {
-                    let arg = match it {
-                        ParamKind::Type => self.new_type_var(),
-                        ParamKind::Lifetime => unreachable!("Tuple with lifetime parameter"),
-                        ParamKind::Const(_) => unreachable!("Tuple with const parameter"),
-                    };
-                    arg_tys.push(arg.to_nextsolver(self.interner));
-                    arg.cast(Interner)
+            let arg_ty = next_solver::Ty::new_tup_from_iter(
+                self.interner,
+                std::iter::repeat_with(|| {
+                    let ty = self.next_ty_var();
+                    arg_tys.push(ty);
+                    ty
                 })
-                .build();
-
-            let b = TyBuilder::trait_ref(self.db, fn_trait);
-            if b.remaining() != 2 {
-                return None;
-            }
-            let mut trait_ref = b.push(ty.clone()).push(arg_ty).build();
-
-            let projection = TyBuilder::assoc_type_projection(
-                self.db,
-                output_assoc_type,
-                Some(trait_ref.substitution.clone()),
-            )
-            .fill_with_unknown()
-            .build();
-
-            let goal: Goal = trait_ref.clone().cast(Interner);
-            if !self.try_obligation(goal.clone()).no_solution() {
-                self.register_obligation(goal.to_nextsolver(self.interner));
-                let return_ty =
-                    self.normalize_projection_ty(projection).to_nextsolver(self.interner);
+                .take(num_args),
+            );
+            let args = [ty.to_nextsolver(self.interner), arg_ty];
+            let trait_ref = crate::next_solver::TraitRef::new(self.interner, fn_trait.into(), args);
+
+            let projection = crate::next_solver::Ty::new_alias(
+                self.interner,
+                rustc_type_ir::AliasTyKind::Projection,
+                crate::next_solver::AliasTy::new(self.interner, output_assoc_type.into(), args),
+            );
+
+            let pred = crate::next_solver::Predicate::upcast_from(trait_ref, self.interner);
+            if !self.try_obligation(pred).no_solution() {
+                self.register_obligation(pred);
+                let return_ty = self.normalize_alias_ty(projection);
                 for &fn_x in subtraits {
                     let fn_x_trait = fn_x.get_id(self.db, krate)?;
-                    trait_ref.trait_id = to_chalk_trait_id(fn_x_trait);
-                    let goal = trait_ref.clone().cast(Interner);
-                    if !self.try_obligation(goal).no_solution() {
+                    let trait_ref =
+                        crate::next_solver::TraitRef::new(self.interner, fn_x_trait.into(), args);
+                    let pred = crate::next_solver::Predicate::upcast_from(trait_ref, self.interner);
+                    if !self.try_obligation(pred).no_solution() {
                         return Some((fn_x, arg_tys, return_ty));
                     }
                 }
@@ -1171,12 +1043,11 @@ impl<'db> InferenceTable<'db> {
         let Some(sized) = LangItem::Sized.resolve_trait(self.db, self.trait_env.krate) else {
             return false;
         };
-        let sized_pred = WhereClause::Implemented(TraitRef {
-            trait_id: to_chalk_trait_id(sized),
-            substitution: Substitution::from1(Interner, ty),
-        });
-        let goal = GoalData::DomainGoal(chalk_ir::DomainGoal::Holds(sized_pred)).intern(Interner);
-        self.try_obligation(goal).certain()
+        let sized_pred = Predicate::upcast_from(
+            TraitRef::new(self.interner, sized.into(), [ty.to_nextsolver(self.interner)]),
+            self.interner,
+        );
+        self.try_obligation(sized_pred).certain()
     }
 }
 
@@ -1192,14 +1063,10 @@ impl fmt::Debug for InferenceTable<'_> {
 mod resolve {
     use super::InferenceTable;
     use crate::{
-        ConcreteConst, Const, ConstData, ConstScalar, ConstValue, DebruijnIndex, GenericArg,
-        InferenceVar, Interner, Lifetime, Ty, TyVariableKind, VariableKind,
-        next_solver::mapping::NextSolverToChalk,
-    };
-    use chalk_ir::{
-        cast::Cast,
-        fold::{TypeFoldable, TypeFolder},
+        Const, DebruijnIndex, GenericArg, InferenceVar, Interner, Lifetime, Ty, TyVariableKind,
+        VariableKind, next_solver::mapping::NextSolverToChalk,
     };
+    use chalk_ir::fold::{TypeFoldable, TypeFolder};
     use rustc_type_ir::{FloatVid, IntVid, TyVid};
 
     #[derive(Debug, Copy, Clone, PartialEq, Eq)]
@@ -1213,7 +1080,7 @@ mod resolve {
     pub(super) struct Resolver<
         'a,
         'b,
-        F: Fn(InferenceVar, VariableKind, GenericArg, DebruijnIndex) -> GenericArg,
+        F: Fn(InferenceVar, VariableKind, DebruijnIndex) -> GenericArg,
     > {
         pub(super) table: &'a mut InferenceTable<'b>,
         pub(super) var_stack: &'a mut Vec<(InferenceVar, VarKind)>,
@@ -1221,7 +1088,7 @@ mod resolve {
     }
     impl<F> TypeFolder<Interner> for Resolver<'_, '_, F>
     where
-        F: Fn(InferenceVar, VariableKind, GenericArg, DebruijnIndex) -> GenericArg,
+        F: Fn(InferenceVar, VariableKind, DebruijnIndex) -> GenericArg,
     {
         fn as_dyn(&mut self) -> &mut dyn TypeFolder<Interner> {
             self
@@ -1243,8 +1110,7 @@ mod resolve {
                     let var = InferenceVar::from(vid.as_u32());
                     if self.var_stack.contains(&(var, VarKind::Ty(kind))) {
                         // recursive type
-                        let default = self.table.fallback_value(var, kind).cast(Interner);
-                        return (self.fallback)(var, VariableKind::Ty(kind), default, outer_binder)
+                        return (self.fallback)(var, VariableKind::Ty(kind), outer_binder)
                             .assert_ty_ref(Interner)
                             .clone();
                     }
@@ -1256,8 +1122,7 @@ mod resolve {
                         self.var_stack.pop();
                         result
                     } else {
-                        let default = self.table.fallback_value(var, kind).cast(Interner);
-                        (self.fallback)(var, VariableKind::Ty(kind), default, outer_binder)
+                        (self.fallback)(var, VariableKind::Ty(kind), outer_binder)
                             .assert_ty_ref(Interner)
                             .clone()
                     }
@@ -1273,8 +1138,7 @@ mod resolve {
                     let var = InferenceVar::from(vid.as_u32());
                     if self.var_stack.contains(&(var, VarKind::Ty(kind))) {
                         // recursive type
-                        let default = self.table.fallback_value(var, kind).cast(Interner);
-                        return (self.fallback)(var, VariableKind::Ty(kind), default, outer_binder)
+                        return (self.fallback)(var, VariableKind::Ty(kind), outer_binder)
                             .assert_ty_ref(Interner)
                             .clone();
                     }
@@ -1286,8 +1150,7 @@ mod resolve {
                         self.var_stack.pop();
                         result
                     } else {
-                        let default = self.table.fallback_value(var, kind).cast(Interner);
-                        (self.fallback)(var, VariableKind::Ty(kind), default, outer_binder)
+                        (self.fallback)(var, VariableKind::Ty(kind), outer_binder)
                             .assert_ty_ref(Interner)
                             .clone()
                     }
@@ -1303,8 +1166,7 @@ mod resolve {
                     let var = InferenceVar::from(vid.as_u32());
                     if self.var_stack.contains(&(var, VarKind::Ty(kind))) {
                         // recursive type
-                        let default = self.table.fallback_value(var, kind).cast(Interner);
-                        return (self.fallback)(var, VariableKind::Ty(kind), default, outer_binder)
+                        return (self.fallback)(var, VariableKind::Ty(kind), outer_binder)
                             .assert_ty_ref(Interner)
                             .clone();
                     }
@@ -1316,8 +1178,7 @@ mod resolve {
                         self.var_stack.pop();
                         result
                     } else {
-                        let default = self.table.fallback_value(var, kind).cast(Interner);
-                        (self.fallback)(var, VariableKind::Ty(kind), default, outer_binder)
+                        (self.fallback)(var, VariableKind::Ty(kind), outer_binder)
                             .assert_ty_ref(Interner)
                             .clone()
                     }
@@ -1336,15 +1197,9 @@ mod resolve {
                 .infer_ctxt
                 .root_const_var(rustc_type_ir::ConstVid::from_u32(var.index()));
             let var = InferenceVar::from(vid.as_u32());
-            let default = ConstData {
-                ty: ty.clone(),
-                value: ConstValue::Concrete(ConcreteConst { interned: ConstScalar::Unknown }),
-            }
-            .intern(Interner)
-            .cast(Interner);
             if self.var_stack.contains(&(var, VarKind::Const)) {
                 // recursive
-                return (self.fallback)(var, VariableKind::Const(ty), default, outer_binder)
+                return (self.fallback)(var, VariableKind::Const(ty), outer_binder)
                     .assert_const_ref(Interner)
                     .clone();
             }
@@ -1356,7 +1211,7 @@ mod resolve {
                 self.var_stack.pop();
                 result
             } else {
-                (self.fallback)(var, VariableKind::Const(ty), default, outer_binder)
+                (self.fallback)(var, VariableKind::Const(ty), outer_binder)
                     .assert_const_ref(Interner)
                     .clone()
             }
@@ -1375,3 +1230,124 @@ mod resolve {
         }
     }
 }
+
+mod resolve_completely {
+    use rustc_type_ir::{
+        DebruijnIndex, Flags, TypeFolder, TypeSuperFoldable,
+        inherent::{Const as _, Ty as _},
+    };
+
+    use crate::next_solver::Region;
+    use crate::{
+        infer::unify::InferenceTable,
+        next_solver::{
+            Const, DbInterner, ErrorGuaranteed, Goal, Predicate, Term, Ty,
+            infer::traits::ObligationCause,
+            normalize::deeply_normalize_with_skipped_universes_and_ambiguous_coroutine_goals,
+        },
+    };
+
+    pub(super) struct Resolver<'a, 'db> {
+        ctx: &'a mut InferenceTable<'db>,
+        /// Whether we should normalize, disabled when resolving predicates.
+        should_normalize: bool,
+        nested_goals: &'a mut Vec<Goal<'db, Predicate<'db>>>,
+    }
+
+    impl<'a, 'db> Resolver<'a, 'db> {
+        pub(super) fn new(
+            ctx: &'a mut InferenceTable<'db>,
+            should_normalize: bool,
+            nested_goals: &'a mut Vec<Goal<'db, Predicate<'db>>>,
+        ) -> Resolver<'a, 'db> {
+            Resolver { ctx, nested_goals, should_normalize }
+        }
+
+        fn handle_term<T>(
+            &mut self,
+            value: T,
+            outer_exclusive_binder: impl FnOnce(T) -> DebruijnIndex,
+        ) -> T
+        where
+            T: Into<Term<'db>> + TypeSuperFoldable<DbInterner<'db>> + Copy,
+        {
+            let value = if self.should_normalize {
+                let cause = ObligationCause::new();
+                let at = self.ctx.infer_ctxt.at(&cause, self.ctx.trait_env.env);
+                let universes = vec![None; outer_exclusive_binder(value).as_usize()];
+                match deeply_normalize_with_skipped_universes_and_ambiguous_coroutine_goals(
+                    at, value, universes,
+                ) {
+                    Ok((value, goals)) => {
+                        self.nested_goals.extend(goals);
+                        value
+                    }
+                    Err(_errors) => {
+                        // FIXME: Report the error.
+                        value
+                    }
+                }
+            } else {
+                value
+            };
+
+            value.fold_with(&mut ReplaceInferWithError { interner: self.ctx.interner })
+        }
+    }
+
+    impl<'cx, 'db> TypeFolder<DbInterner<'db>> for Resolver<'cx, 'db> {
+        fn cx(&self) -> DbInterner<'db> {
+            self.ctx.interner
+        }
+
+        fn fold_region(&mut self, r: Region<'db>) -> Region<'db> {
+            if r.is_var() { Region::error(self.ctx.interner) } else { r }
+        }
+
+        fn fold_ty(&mut self, ty: Ty<'db>) -> Ty<'db> {
+            self.handle_term(ty, |it| it.outer_exclusive_binder())
+        }
+
+        fn fold_const(&mut self, ct: Const<'db>) -> Const<'db> {
+            self.handle_term(ct, |it| it.outer_exclusive_binder())
+        }
+
+        fn fold_predicate(&mut self, predicate: Predicate<'db>) -> Predicate<'db> {
+            assert!(
+                !self.should_normalize,
+                "normalizing predicates in writeback is not generally sound"
+            );
+            predicate.super_fold_with(self)
+        }
+    }
+
+    struct ReplaceInferWithError<'db> {
+        interner: DbInterner<'db>,
+    }
+
+    impl<'db> TypeFolder<DbInterner<'db>> for ReplaceInferWithError<'db> {
+        fn cx(&self) -> DbInterner<'db> {
+            self.interner
+        }
+
+        fn fold_ty(&mut self, t: Ty<'db>) -> Ty<'db> {
+            if t.is_infer() {
+                Ty::new_error(self.interner, ErrorGuaranteed)
+            } else {
+                t.super_fold_with(self)
+            }
+        }
+
+        fn fold_const(&mut self, c: Const<'db>) -> Const<'db> {
+            if c.is_ct_infer() {
+                Const::new_error(self.interner, ErrorGuaranteed)
+            } else {
+                c.super_fold_with(self)
+            }
+        }
+
+        fn fold_region(&mut self, r: Region<'db>) -> Region<'db> {
+            if r.is_var() { Region::error(self.interner) } else { r }
+        }
+    }
+}
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/inhabitedness.rs b/src/tools/rust-analyzer/crates/hir-ty/src/inhabitedness.rs
index b16b6a11784..bdebe41b299 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/inhabitedness.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/inhabitedness.rs
@@ -20,7 +20,7 @@ pub(crate) fn is_ty_uninhabited_from(
     db: &dyn HirDatabase,
     ty: &Ty,
     target_mod: ModuleId,
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'_>>,
 ) -> bool {
     let _p = tracing::info_span!("is_ty_uninhabited_from", ?ty).entered();
     let mut uninhabited_from =
@@ -36,7 +36,7 @@ pub(crate) fn is_enum_variant_uninhabited_from(
     variant: EnumVariantId,
     subst: &Substitution,
     target_mod: ModuleId,
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'_>>,
 ) -> bool {
     let _p = tracing::info_span!("is_enum_variant_uninhabited_from").entered();
 
@@ -52,7 +52,7 @@ struct UninhabitedFrom<'a> {
     // guard for preventing stack overflow in non trivial non terminating types
     max_depth: usize,
     db: &'a dyn HirDatabase,
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'a>>,
 }
 
 const CONTINUE_OPAQUELY_INHABITED: ControlFlow<VisiblyUninhabited> = Continue(());
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/layout.rs b/src/tools/rust-analyzer/crates/hir-ty/src/layout.rs
index f21673c732e..4071b9a1d5e 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/layout.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/layout.rs
@@ -132,7 +132,7 @@ fn layout_of_simd_ty<'db>(
     id: StructId,
     repr_packed: bool,
     args: &GenericArgs<'db>,
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'db>>,
     dl: &TargetDataLayout,
 ) -> Result<Arc<Layout>, LayoutError> {
     // Supported SIMD vectors are homogeneous ADTs with exactly one array field:
@@ -160,7 +160,7 @@ fn layout_of_simd_ty<'db>(
 pub fn layout_of_ty_query<'db>(
     db: &'db dyn HirDatabase,
     ty: Ty<'db>,
-    trait_env: Arc<TraitEnvironment>,
+    trait_env: Arc<TraitEnvironment<'db>>,
 ) -> Result<Arc<Layout>, LayoutError> {
     let krate = trait_env.krate;
     let interner = DbInterner::new_with(db, Some(krate), trait_env.block);
@@ -371,7 +371,7 @@ pub fn layout_of_ty_query<'db>(
 pub(crate) fn layout_of_ty_cycle_result<'db>(
     _: &dyn HirDatabase,
     _: Ty<'db>,
-    _: Arc<TraitEnvironment>,
+    _: Arc<TraitEnvironment<'db>>,
 ) -> Result<Arc<Layout>, LayoutError> {
     Err(LayoutError::RecursiveTypeWithoutIndirection)
 }
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/layout/adt.rs b/src/tools/rust-analyzer/crates/hir-ty/src/layout/adt.rs
index 9a746ca8885..a8f04bf8c13 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/layout/adt.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/layout/adt.rs
@@ -23,7 +23,7 @@ pub fn layout_of_adt_query<'db>(
     db: &'db dyn HirDatabase,
     def: AdtId,
     args: GenericArgs<'db>,
-    trait_env: Arc<TraitEnvironment>,
+    trait_env: Arc<TraitEnvironment<'db>>,
 ) -> Result<Arc<Layout>, LayoutError> {
     let krate = trait_env.krate;
     let Ok(target) = db.target_data_layout(krate) else {
@@ -99,7 +99,7 @@ pub(crate) fn layout_of_adt_cycle_result<'db>(
     _: &'db dyn HirDatabase,
     _def: AdtId,
     _args: GenericArgs<'db>,
-    _trait_env: Arc<TraitEnvironment>,
+    _trait_env: Arc<TraitEnvironment<'db>>,
 ) -> Result<Arc<Layout>, LayoutError> {
     Err(LayoutError::RecursiveTypeWithoutIndirection)
 }
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/layout/tests.rs b/src/tools/rust-analyzer/crates/hir-ty/src/layout/tests.rs
index 8be5eaca63b..275ad841f4b 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/layout/tests.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/layout/tests.rs
@@ -1,18 +1,17 @@
 use base_db::target::TargetData;
-use chalk_ir::{AdtId, TyKind};
 use either::Either;
 use hir_def::db::DefDatabase;
 use project_model::{Sysroot, toolchain_info::QueryConfig};
 use rustc_hash::FxHashMap;
+use rustc_type_ir::inherent::{GenericArgs as _, Ty as _};
 use syntax::ToSmolStr;
 use test_fixture::WithFixture;
 use triomphe::Arc;
 
 use crate::{
-    Interner, Substitution,
     db::HirDatabase,
     layout::{Layout, LayoutError},
-    next_solver::{DbInterner, mapping::ChalkToNextSolver},
+    next_solver::{AdtDef, DbInterner, GenericArgs, mapping::ChalkToNextSolver},
     setup_tracing,
     test_db::TestDB,
 };
@@ -80,18 +79,18 @@ fn eval_goal(
             Some(adt_or_type_alias_id)
         })
         .unwrap();
-    let goal_ty = match adt_or_type_alias_id {
-        Either::Left(adt_id) => {
-            TyKind::Adt(AdtId(adt_id), Substitution::empty(Interner)).intern(Interner)
-        }
-        Either::Right(ty_id) => {
-            db.ty(ty_id.into()).substitute(Interner, &Substitution::empty(Interner))
-        }
-    };
     salsa::attach(&db, || {
         let interner = DbInterner::new_with(&db, None, None);
+        let goal_ty = match adt_or_type_alias_id {
+            Either::Left(adt_id) => crate::next_solver::Ty::new_adt(
+                interner,
+                AdtDef::new(adt_id, interner),
+                GenericArgs::identity_for_item(interner, adt_id.into()),
+            ),
+            Either::Right(ty_id) => db.ty(ty_id.into()).instantiate_identity(),
+        };
         db.layout_of_ty(
-            goal_ty.to_nextsolver(interner),
+            goal_ty,
             db.trait_environment(match adt_or_type_alias_id {
                 Either::Left(adt) => hir_def::GenericDefId::AdtId(adt),
                 Either::Right(ty) => hir_def::GenericDefId::TypeAliasId(ty),
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/lib.rs b/src/tools/rust-analyzer/crates/hir-ty/src/lib.rs
index 2e59a488e67..281cf6b2d4b 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/lib.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/lib.rs
@@ -72,7 +72,10 @@ use intern::{Symbol, sym};
 use la_arena::{Arena, Idx};
 use mir::{MirEvalError, VTableMap};
 use rustc_hash::{FxBuildHasher, FxHashMap, FxHashSet};
-use rustc_type_ir::inherent::SliceLike;
+use rustc_type_ir::{
+    UpcastFrom,
+    inherent::{SliceLike, Ty as _},
+};
 use syntax::ast::{ConstArg, make};
 use traits::FnTrait;
 use triomphe::Arc;
@@ -85,7 +88,7 @@ use crate::{
     infer::unify::InferenceTable,
     next_solver::{
         DbInterner,
-        mapping::{ChalkToNextSolver, convert_ty_for_result},
+        mapping::{ChalkToNextSolver, NextSolverToChalk, convert_ty_for_result},
     },
 };
 
@@ -554,8 +557,10 @@ impl CallableSig {
 
     pub fn from_def(db: &dyn HirDatabase, def: FnDefId, substs: &Substitution) -> CallableSig {
         let callable_def = ToChalk::from_chalk(db, def);
+        let interner = DbInterner::new_with(db, None, None);
+        let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
         let sig = db.callable_item_signature(callable_def);
-        sig.substitute(Interner, substs)
+        sig.instantiate(interner, args).skip_binder().to_chalk(interner)
     }
     pub fn from_fn_ptr(fn_ptr: &FnPointer) -> CallableSig {
         CallableSig {
@@ -916,10 +921,10 @@ where
     Canonical { value, binders: chalk_ir::CanonicalVarKinds::from_iter(Interner, kinds) }
 }
 
-pub fn callable_sig_from_fn_trait(
+pub fn callable_sig_from_fn_trait<'db>(
     self_ty: &Ty,
-    trait_env: Arc<TraitEnvironment>,
-    db: &dyn HirDatabase,
+    trait_env: Arc<TraitEnvironment<'db>>,
+    db: &'db dyn HirDatabase,
 ) -> Option<(FnTrait, CallableSig)> {
     let krate = trait_env.krate;
     let fn_once_trait = FnTrait::FnOnce.get_id(db, krate)?;
@@ -936,26 +941,32 @@ pub fn callable_sig_from_fn_trait(
     // Register two obligations:
     // - Self: FnOnce<?args_ty>
     // - <Self as FnOnce<?args_ty>>::Output == ?ret_ty
-    let args_ty = table.new_type_var();
-    let mut trait_ref = b.push(self_ty.clone()).push(args_ty.clone()).build();
-    let projection = TyBuilder::assoc_type_projection(
-        db,
-        output_assoc_type,
-        Some(trait_ref.substitution.clone()),
-    )
-    .build();
-
-    let goal: Goal = trait_ref.clone().cast(Interner);
-    let pred = goal.to_nextsolver(table.interner);
-    if !table.try_obligation(goal).no_solution() {
+    let args_ty = table.next_ty_var();
+    let args = [self_ty.to_nextsolver(table.interner), args_ty];
+    let trait_ref = crate::next_solver::TraitRef::new(table.interner, fn_once_trait.into(), args);
+    let projection = crate::next_solver::Ty::new_alias(
+        table.interner,
+        rustc_type_ir::AliasTyKind::Projection,
+        crate::next_solver::AliasTy::new(table.interner, output_assoc_type.into(), args),
+    );
+
+    let pred = crate::next_solver::Predicate::upcast_from(trait_ref, table.interner);
+    if !table.try_obligation(pred).no_solution() {
         table.register_obligation(pred);
-        let return_ty = table.normalize_projection_ty(projection);
+        let return_ty = table.normalize_alias_ty(projection);
         for fn_x in [FnTrait::Fn, FnTrait::FnMut, FnTrait::FnOnce] {
             let fn_x_trait = fn_x.get_id(db, krate)?;
-            trait_ref.trait_id = to_chalk_trait_id(fn_x_trait);
-            if !table.try_obligation(trait_ref.clone().cast(Interner)).no_solution() {
-                let ret_ty = table.resolve_completely(return_ty);
-                let args_ty = table.resolve_completely(args_ty);
+            let trait_ref =
+                crate::next_solver::TraitRef::new(table.interner, fn_x_trait.into(), args);
+            if !table
+                .try_obligation(crate::next_solver::Predicate::upcast_from(
+                    trait_ref,
+                    table.interner,
+                ))
+                .no_solution()
+            {
+                let ret_ty = table.resolve_completely(return_ty.to_chalk(table.interner));
+                let args_ty = table.resolve_completely(args_ty.to_chalk(table.interner));
                 let params = args_ty
                     .as_tuple()?
                     .iter(Interner)
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/lower.rs b/src/tools/rust-analyzer/crates/hir-ty/src/lower.rs
index 4d5172fd4f2..0c197b27034 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/lower.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/lower.rs
@@ -24,19 +24,18 @@ use chalk_ir::{
 
 use either::Either;
 use hir_def::{
-    AdtId, AssocItemId, CallableDefId, ConstId, ConstParamId, DefWithBodyId, EnumId, EnumVariantId,
-    FunctionId, GenericDefId, GenericParamId, HasModule, ImplId, ItemContainerId, LocalFieldId,
-    Lookup, StaticId, StructId, TypeAliasId, TypeOrConstParamId, UnionId, VariantId,
+    AdtId, AssocItemId, ConstId, ConstParamId, EnumId, EnumVariantId, FunctionId, GenericDefId,
+    GenericParamId, ItemContainerId, LocalFieldId, Lookup, StaticId, StructId, TypeAliasId,
+    TypeOrConstParamId, UnionId, VariantId,
     builtin_type::BuiltinType,
     expr_store::{ExpressionStore, path::Path},
     hir::generics::{GenericParamDataRef, TypeOrConstParamData, WherePredicate},
-    item_tree::FieldsShape,
     lang_item::LangItem,
     resolver::{HasResolver, LifetimeNs, Resolver, TypeNs},
-    signatures::{FunctionSignature, TraitFlags, TypeAliasFlags},
+    signatures::{FunctionSignature, TraitFlags},
     type_ref::{
-        ConstRef, LifetimeRefId, LiteralConstRef, PathId, TraitBoundModifier,
-        TraitRef as HirTraitRef, TypeBound, TypeRef, TypeRefId,
+        ConstRef, LifetimeRefId, LiteralConstRef, PathId, TraitBoundModifier, TypeBound, TypeRef,
+        TypeRefId,
     },
 };
 use hir_expand::name::Name;
@@ -46,11 +45,10 @@ use stdx::{impl_from, never};
 use triomphe::{Arc, ThinArc};
 
 use crate::{
-    AliasTy, Binders, BoundVar, CallableSig, Const, DebruijnIndex, DomainGoal, DynTy, FnAbi,
-    FnPointer, FnSig, FnSubst, ImplTrait, ImplTraitId, ImplTraits, Interner, Lifetime,
-    LifetimeData, LifetimeOutlives, PolyFnSig, QuantifiedWhereClause, QuantifiedWhereClauses,
-    Substitution, TraitEnvironment, TraitRef, TraitRefExt, Ty, TyBuilder, TyKind, WhereClause,
-    all_super_traits,
+    AliasTy, Binders, BoundVar, Const, DebruijnIndex, DynTy, FnAbi, FnPointer, FnSig, FnSubst,
+    ImplTrait, ImplTraitId, ImplTraits, Interner, Lifetime, LifetimeData, LifetimeOutlives,
+    QuantifiedWhereClause, QuantifiedWhereClauses, Substitution, TraitRef, TraitRefExt, Ty,
+    TyBuilder, TyKind, WhereClause, all_super_traits,
     consteval::{intern_const_ref, path_to_const, unknown_const, unknown_const_as_generic},
     db::HirDatabase,
     error_lifetime,
@@ -60,7 +58,11 @@ use crate::{
         path::{PathDiagnosticCallback, PathLoweringContext},
     },
     make_binders,
-    mapping::{ToChalk, from_chalk_trait_id, lt_to_placeholder_idx},
+    mapping::{from_chalk_trait_id, lt_to_placeholder_idx},
+    next_solver::{
+        DbInterner,
+        mapping::{ChalkToNextSolver, NextSolverToChalk},
+    },
     static_lifetime, to_chalk_trait_id, to_placeholder_idx,
     utils::all_super_trait_refs,
     variable_kinds_from_iter,
@@ -567,14 +569,6 @@ impl<'a> TyLoweringContext<'a> {
         Some((ctx.lower_trait_ref_from_resolved_path(resolved, explicit_self_ty, false), ctx))
     }
 
-    fn lower_trait_ref(
-        &mut self,
-        trait_ref: &HirTraitRef,
-        explicit_self_ty: Ty,
-    ) -> Option<TraitRef> {
-        self.lower_trait_ref_from_path(trait_ref.path, explicit_self_ty).map(|it| it.0)
-    }
-
     /// When lowering predicates from parents (impl, traits) for children defs (fns, consts, types), `generics` should
     /// contain the `Generics` for the **child**, while `predicate_owner` should contain the `GenericDefId` of the
     /// **parent**. This is important so we generate the correct bound var/placeholder.
@@ -826,15 +820,6 @@ impl<'a> TyLoweringContext<'a> {
     }
 }
 
-/// Build the signature of a callable item (function, struct or enum variant).
-pub(crate) fn callable_item_signature_query(db: &dyn HirDatabase, def: CallableDefId) -> PolyFnSig {
-    match def {
-        CallableDefId::FunctionId(f) => fn_sig_for_fn(db, f),
-        CallableDefId::StructId(s) => fn_sig_for_struct_constructor(db, s),
-        CallableDefId::EnumVariantId(e) => fn_sig_for_enum_variant_constructor(db, e),
-    }
-}
-
 fn named_associated_type_shorthand_candidates<R>(
     db: &dyn HirDatabase,
     // If the type parameter is defined in an impl and we're in a method, there
@@ -862,21 +847,21 @@ fn named_associated_type_shorthand_candidates<R>(
         })
     };
 
+    let interner = DbInterner::new_with(db, None, None);
     match res {
         TypeNs::SelfType(impl_id) => {
-            // we're _in_ the impl -- the binders get added back later. Correct,
-            // but it would be nice to make this more explicit
-            let trait_ref = db.impl_trait(impl_id)?.into_value_and_skipped_binders().0;
+            let trait_ref = db.impl_trait(impl_id)?;
 
             let impl_id_as_generic_def: GenericDefId = impl_id.into();
             if impl_id_as_generic_def != def {
                 let subst = TyBuilder::subst_for_def(db, impl_id, None)
                     .fill_with_bound_vars(DebruijnIndex::INNERMOST, 0)
                     .build();
-                let trait_ref = subst.apply(trait_ref, Interner);
+                let args: crate::next_solver::GenericArgs<'_> = subst.to_nextsolver(interner);
+                let trait_ref = trait_ref.instantiate(interner, args).to_chalk(interner);
                 search(trait_ref)
             } else {
-                search(trait_ref)
+                search(trait_ref.skip_binder().to_chalk(interner))
             }
         }
         TypeNs::GenericParam(param_id) => {
@@ -919,7 +904,7 @@ pub(crate) fn field_types_query(
     db: &dyn HirDatabase,
     variant_id: VariantId,
 ) -> Arc<ArenaMap<LocalFieldId, Binders<Ty>>> {
-    db.field_types_with_diagnostics(variant_id).0
+    field_types_with_diagnostics_query(db, variant_id).0
 }
 
 /// Build the type of all specific fields of a struct or enum variant.
@@ -1086,102 +1071,6 @@ pub(crate) fn generic_predicates_for_param_cycle_result(
     GenericPredicates(None)
 }
 
-pub(crate) fn trait_environment_for_body_query(
-    db: &dyn HirDatabase,
-    def: DefWithBodyId,
-) -> Arc<TraitEnvironment> {
-    let Some(def) = def.as_generic_def_id(db) else {
-        let krate = def.module(db).krate();
-        return TraitEnvironment::empty(krate);
-    };
-    db.trait_environment(def)
-}
-
-pub(crate) fn trait_environment_query(
-    db: &dyn HirDatabase,
-    def: GenericDefId,
-) -> Arc<TraitEnvironment> {
-    let generics = generics(db, def);
-    if generics.has_no_predicates() && generics.is_empty() {
-        return TraitEnvironment::empty(def.krate(db));
-    }
-
-    let resolver = def.resolver(db);
-    let mut ctx = TyLoweringContext::new(
-        db,
-        &resolver,
-        generics.store(),
-        def,
-        LifetimeElisionKind::AnonymousReportError,
-    )
-    .with_type_param_mode(ParamLoweringMode::Placeholder);
-    let mut traits_in_scope = Vec::new();
-    let mut clauses = Vec::new();
-    for maybe_parent_generics in
-        std::iter::successors(Some(&generics), |generics| generics.parent_generics())
-    {
-        ctx.store = maybe_parent_generics.store();
-        for pred in maybe_parent_generics.where_predicates() {
-            for pred in ctx.lower_where_predicate(pred, false) {
-                if let WhereClause::Implemented(tr) = pred.skip_binders() {
-                    traits_in_scope
-                        .push((tr.self_type_parameter(Interner).clone(), tr.hir_trait_id()));
-                }
-                let program_clause: Binders<DomainGoal> =
-                    pred.map(|pred| pred.into_from_env_goal(Interner).cast(Interner));
-                clauses.push(program_clause);
-            }
-        }
-    }
-
-    if let Some(trait_id) = def.assoc_trait_container(db) {
-        // add `Self: Trait<T1, T2, ...>` to the environment in trait
-        // function default implementations (and speculative code
-        // inside consts or type aliases)
-        cov_mark::hit!(trait_self_implements_self);
-        let substs = TyBuilder::placeholder_subst(db, trait_id);
-        let trait_ref = TraitRef { trait_id: to_chalk_trait_id(trait_id), substitution: substs };
-        let pred = WhereClause::Implemented(trait_ref);
-        clauses.push(Binders::empty(
-            Interner,
-            pred.cast::<DomainGoal>(Interner).into_from_env_goal(Interner),
-        ));
-    }
-
-    let subst = generics.placeholder_subst(db);
-    if !subst.is_empty(Interner) {
-        let explicitly_unsized_tys = ctx.unsized_types;
-        if let Some(implicitly_sized_clauses) =
-            implicitly_sized_clauses(db, def, &explicitly_unsized_tys, &subst, &resolver)
-        {
-            clauses.extend(implicitly_sized_clauses.map(|pred| {
-                Binders::empty(
-                    Interner,
-                    pred.into_from_env_goal(Interner).cast::<DomainGoal>(Interner),
-                )
-            }));
-        };
-    }
-
-    let clauses = chalk_ir::ProgramClauses::from_iter(
-        Interner,
-        clauses.into_iter().map(|g| {
-            chalk_ir::ProgramClause::new(
-                Interner,
-                chalk_ir::ProgramClauseData(g.map(|g| chalk_ir::ProgramClauseImplication {
-                    consequence: g,
-                    conditions: chalk_ir::Goals::empty(Interner),
-                    constraints: chalk_ir::Constraints::empty(Interner),
-                    priority: chalk_ir::ClausePriority::High,
-                })),
-            )
-        }),
-    );
-    let env = chalk_ir::Environment { clauses };
-
-    TraitEnvironment::new(resolver.krate(), None, traits_in_scope.into_boxed_slice(), env)
-}
-
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct GenericPredicates(Option<Arc<[Binders<QuantifiedWhereClause>]>>);
 
@@ -1410,208 +1299,6 @@ pub(crate) fn generic_defaults_with_diagnostics_cycle_result(
     (GenericDefaults(None), None)
 }
 
-fn fn_sig_for_fn(db: &dyn HirDatabase, def: FunctionId) -> PolyFnSig {
-    let data = db.function_signature(def);
-    let resolver = def.resolver(db);
-    let mut ctx_params = TyLoweringContext::new(
-        db,
-        &resolver,
-        &data.store,
-        def.into(),
-        LifetimeElisionKind::for_fn_params(&data),
-    )
-    .with_type_param_mode(ParamLoweringMode::Variable);
-    let params = data.params.iter().map(|&tr| ctx_params.lower_ty(tr));
-
-    let ret = match data.ret_type {
-        Some(ret_type) => {
-            let mut ctx_ret = TyLoweringContext::new(
-                db,
-                &resolver,
-                &data.store,
-                def.into(),
-                LifetimeElisionKind::for_fn_ret(),
-            )
-            .with_impl_trait_mode(ImplTraitLoweringMode::Opaque)
-            .with_type_param_mode(ParamLoweringMode::Variable);
-            ctx_ret.lower_ty(ret_type)
-        }
-        None => TyKind::Tuple(0, Substitution::empty(Interner)).intern(Interner),
-    };
-    let generics = generics(db, def.into());
-    let sig = CallableSig::from_params_and_return(
-        params,
-        ret,
-        data.is_varargs(),
-        if data.is_unsafe() { Safety::Unsafe } else { Safety::Safe },
-        data.abi.as_ref().map_or(FnAbi::Rust, FnAbi::from_symbol),
-    );
-    make_binders(db, &generics, sig)
-}
-
-/// Build the declared type of a function. This should not need to look at the
-/// function body.
-fn type_for_fn(db: &dyn HirDatabase, def: FunctionId) -> Binders<Ty> {
-    let generics = generics(db, def.into());
-    let substs = generics.bound_vars_subst(db, DebruijnIndex::INNERMOST);
-    make_binders(
-        db,
-        &generics,
-        TyKind::FnDef(CallableDefId::FunctionId(def).to_chalk(db), substs).intern(Interner),
-    )
-}
-
-/// Build the declared type of a const.
-fn type_for_const(db: &dyn HirDatabase, def: ConstId) -> Binders<Ty> {
-    let data = db.const_signature(def);
-    let generics = generics(db, def.into());
-    let resolver = def.resolver(db);
-    let parent = def.loc(db).container;
-    let mut ctx = TyLoweringContext::new(
-        db,
-        &resolver,
-        &data.store,
-        def.into(),
-        LifetimeElisionKind::for_const(parent),
-    )
-    .with_type_param_mode(ParamLoweringMode::Variable);
-
-    make_binders(db, &generics, ctx.lower_ty(data.type_ref))
-}
-
-/// Build the declared type of a static.
-fn type_for_static(db: &dyn HirDatabase, def: StaticId) -> Binders<Ty> {
-    let data = db.static_signature(def);
-    let resolver = def.resolver(db);
-    let mut ctx = TyLoweringContext::new(
-        db,
-        &resolver,
-        &data.store,
-        def.into(),
-        LifetimeElisionKind::Elided(static_lifetime()),
-    );
-
-    Binders::empty(Interner, ctx.lower_ty(data.type_ref))
-}
-
-fn fn_sig_for_struct_constructor(db: &dyn HirDatabase, def: StructId) -> PolyFnSig {
-    let field_tys = db.field_types(def.into());
-    let params = field_tys.iter().map(|(_, ty)| ty.skip_binders().clone());
-    let (ret, binders) = type_for_adt(db, def.into()).into_value_and_skipped_binders();
-    Binders::new(
-        binders,
-        CallableSig::from_params_and_return(params, ret, false, Safety::Safe, FnAbi::RustCall),
-    )
-}
-
-/// Build the type of a tuple struct constructor.
-fn type_for_struct_constructor(db: &dyn HirDatabase, def: StructId) -> Option<Binders<Ty>> {
-    let struct_data = def.fields(db);
-    match struct_data.shape {
-        FieldsShape::Record => None,
-        FieldsShape::Unit => Some(type_for_adt(db, def.into())),
-        FieldsShape::Tuple => {
-            let generics = generics(db, AdtId::from(def).into());
-            let substs = generics.bound_vars_subst(db, DebruijnIndex::INNERMOST);
-            Some(make_binders(
-                db,
-                &generics,
-                TyKind::FnDef(CallableDefId::StructId(def).to_chalk(db), substs).intern(Interner),
-            ))
-        }
-    }
-}
-
-fn fn_sig_for_enum_variant_constructor(db: &dyn HirDatabase, def: EnumVariantId) -> PolyFnSig {
-    let field_tys = db.field_types(def.into());
-    let params = field_tys.iter().map(|(_, ty)| ty.skip_binders().clone());
-    let parent = def.lookup(db).parent;
-    let (ret, binders) = type_for_adt(db, parent.into()).into_value_and_skipped_binders();
-    Binders::new(
-        binders,
-        CallableSig::from_params_and_return(params, ret, false, Safety::Safe, FnAbi::RustCall),
-    )
-}
-
-/// Build the type of a tuple enum variant constructor.
-fn type_for_enum_variant_constructor(
-    db: &dyn HirDatabase,
-    def: EnumVariantId,
-) -> Option<Binders<Ty>> {
-    let e = def.lookup(db).parent;
-    match def.fields(db).shape {
-        FieldsShape::Record => None,
-        FieldsShape::Unit => Some(type_for_adt(db, e.into())),
-        FieldsShape::Tuple => {
-            let generics = generics(db, e.into());
-            let substs = generics.bound_vars_subst(db, DebruijnIndex::INNERMOST);
-            Some(make_binders(
-                db,
-                &generics,
-                TyKind::FnDef(CallableDefId::EnumVariantId(def).to_chalk(db), substs)
-                    .intern(Interner),
-            ))
-        }
-    }
-}
-
-#[salsa_macros::tracked(cycle_result = type_for_adt_cycle_result)]
-fn type_for_adt_tracked(db: &dyn HirDatabase, adt: AdtId) -> Binders<Ty> {
-    type_for_adt(db, adt)
-}
-
-fn type_for_adt_cycle_result(db: &dyn HirDatabase, adt: AdtId) -> Binders<Ty> {
-    let generics = generics(db, adt.into());
-    make_binders(db, &generics, TyKind::Error.intern(Interner))
-}
-
-fn type_for_adt(db: &dyn HirDatabase, adt: AdtId) -> Binders<Ty> {
-    let generics = generics(db, adt.into());
-    let subst = generics.bound_vars_subst(db, DebruijnIndex::INNERMOST);
-    let ty = TyKind::Adt(crate::AdtId(adt), subst).intern(Interner);
-    make_binders(db, &generics, ty)
-}
-
-pub(crate) fn type_for_type_alias_with_diagnostics_query(
-    db: &dyn HirDatabase,
-    t: TypeAliasId,
-) -> (Binders<Ty>, Diagnostics) {
-    let generics = generics(db, t.into());
-    let type_alias_data = db.type_alias_signature(t);
-    let mut diags = None;
-    let inner = if type_alias_data.flags.contains(TypeAliasFlags::IS_EXTERN) {
-        TyKind::Foreign(crate::to_foreign_def_id(t)).intern(Interner)
-    } else {
-        let resolver = t.resolver(db);
-        let alias = db.type_alias_signature(t);
-        let mut ctx = TyLoweringContext::new(
-            db,
-            &resolver,
-            &alias.store,
-            t.into(),
-            LifetimeElisionKind::AnonymousReportError,
-        )
-        .with_impl_trait_mode(ImplTraitLoweringMode::Opaque)
-        .with_type_param_mode(ParamLoweringMode::Variable);
-        let res = alias
-            .ty
-            .map(|type_ref| ctx.lower_ty(type_ref))
-            .unwrap_or_else(|| TyKind::Error.intern(Interner));
-        diags = create_diagnostics(ctx.diagnostics);
-        res
-    };
-
-    (make_binders(db, &generics, inner), diags)
-}
-
-pub(crate) fn type_for_type_alias_with_diagnostics_cycle_result(
-    db: &dyn HirDatabase,
-    adt: TypeAliasId,
-) -> (Binders<Ty>, Diagnostics) {
-    let generics = generics(db, adt.into());
-    (make_binders(db, &generics, TyKind::Error.intern(Interner)), None)
-}
-
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum TyDefId {
     BuiltinType(BuiltinType),
@@ -1644,64 +1331,8 @@ impl ValueTyDefId {
     }
 }
 
-/// Build the declared type of an item. This depends on the namespace; e.g. for
-/// `struct Foo(usize)`, we have two types: The type of the struct itself, and
-/// the constructor function `(usize) -> Foo` which lives in the values
-/// namespace.
-pub(crate) fn ty_query(db: &dyn HirDatabase, def: TyDefId) -> Binders<Ty> {
-    match def {
-        TyDefId::BuiltinType(it) => Binders::empty(Interner, TyBuilder::builtin(it)),
-        TyDefId::AdtId(it) => type_for_adt_tracked(db, it),
-        TyDefId::TypeAliasId(it) => db.type_for_type_alias_with_diagnostics(it).0,
-    }
-}
-
-pub(crate) fn value_ty_query(db: &dyn HirDatabase, def: ValueTyDefId) -> Option<Binders<Ty>> {
-    match def {
-        ValueTyDefId::FunctionId(it) => Some(type_for_fn(db, it)),
-        ValueTyDefId::StructId(it) => type_for_struct_constructor(db, it),
-        ValueTyDefId::UnionId(it) => Some(type_for_adt(db, it.into())),
-        ValueTyDefId::EnumVariantId(it) => type_for_enum_variant_constructor(db, it),
-        ValueTyDefId::ConstId(it) => Some(type_for_const(db, it)),
-        ValueTyDefId::StaticId(it) => Some(type_for_static(db, it)),
-    }
-}
-
-pub(crate) fn impl_self_ty_query(db: &dyn HirDatabase, impl_id: ImplId) -> Binders<Ty> {
-    db.impl_self_ty_with_diagnostics(impl_id).0
-}
-
-pub(crate) fn impl_self_ty_with_diagnostics_query(
-    db: &dyn HirDatabase,
-    impl_id: ImplId,
-) -> (Binders<Ty>, Diagnostics) {
-    let impl_data = db.impl_signature(impl_id);
-    let resolver = impl_id.resolver(db);
-    let generics = generics(db, impl_id.into());
-    let mut ctx = TyLoweringContext::new(
-        db,
-        &resolver,
-        &impl_data.store,
-        impl_id.into(),
-        LifetimeElisionKind::AnonymousCreateParameter { report_in_path: true },
-    )
-    .with_type_param_mode(ParamLoweringMode::Variable);
-    (
-        make_binders(db, &generics, ctx.lower_ty(impl_data.self_ty)),
-        create_diagnostics(ctx.diagnostics),
-    )
-}
-
-pub(crate) fn impl_self_ty_with_diagnostics_cycle_result(
-    db: &dyn HirDatabase,
-    impl_id: ImplId,
-) -> (Binders<Ty>, Diagnostics) {
-    let generics = generics(db, impl_id.into());
-    (make_binders(db, &generics, TyKind::Error.intern(Interner)), None)
-}
-
 pub(crate) fn const_param_ty_query(db: &dyn HirDatabase, def: ConstParamId) -> Ty {
-    db.const_param_ty_with_diagnostics(def).0
+    const_param_ty_with_diagnostics_query(db, def).0
 }
 
 // returns None if def is a type arg
@@ -1729,36 +1360,12 @@ pub(crate) fn const_param_ty_with_diagnostics_query(
     (ty, create_diagnostics(ctx.diagnostics))
 }
 
-pub(crate) fn const_param_ty_with_diagnostics_cycle_result(
+pub(crate) fn const_param_ty_cycle_result(
     _: &dyn HirDatabase,
     _: crate::db::HirDatabaseData,
     _: ConstParamId,
-) -> (Ty, Diagnostics) {
-    (TyKind::Error.intern(Interner), None)
-}
-
-pub(crate) fn impl_trait_query(db: &dyn HirDatabase, impl_id: ImplId) -> Option<Binders<TraitRef>> {
-    db.impl_trait_with_diagnostics(impl_id).map(|it| it.0)
-}
-
-pub(crate) fn impl_trait_with_diagnostics_query(
-    db: &dyn HirDatabase,
-    impl_id: ImplId,
-) -> Option<(Binders<TraitRef>, Diagnostics)> {
-    let impl_data = db.impl_signature(impl_id);
-    let resolver = impl_id.resolver(db);
-    let mut ctx = TyLoweringContext::new(
-        db,
-        &resolver,
-        &impl_data.store,
-        impl_id.into(),
-        LifetimeElisionKind::AnonymousCreateParameter { report_in_path: true },
-    )
-    .with_type_param_mode(ParamLoweringMode::Variable);
-    let (self_ty, binders) = db.impl_self_ty(impl_id).into_value_and_skipped_binders();
-    let target_trait = impl_data.target_trait.as_ref()?;
-    let trait_ref = Binders::new(binders, ctx.lower_trait_ref(target_trait, self_ty)?);
-    Some((trait_ref, create_diagnostics(ctx.diagnostics)))
+) -> Ty {
+    TyKind::Error.intern(Interner)
 }
 
 pub(crate) fn return_type_impl_traits(
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/lower/path.rs b/src/tools/rust-analyzer/crates/hir-ty/src/lower/path.rs
index b0132e4dcbc..da9dd21183e 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/lower/path.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/lower/path.rs
@@ -28,6 +28,10 @@ use crate::{
     error_lifetime,
     generics::{Generics, generics},
     lower::{LifetimeElisionKind, named_associated_type_shorthand_candidates},
+    next_solver::{
+        DbInterner,
+        mapping::{ChalkToNextSolver, NextSolverToChalk},
+    },
     static_lifetime, to_assoc_type_id, to_chalk_trait_id, to_placeholder_idx,
     utils::associated_type_by_name_including_super_traits,
 };
@@ -251,12 +255,20 @@ impl<'a, 'b> PathLoweringContext<'a, 'b> {
                         // `def` can be either impl itself or item within, and we need impl itself
                         // now.
                         let generics = generics.parent_or_self();
+                        let interner = DbInterner::new_with(self.ctx.db, None, None);
                         let subst = generics.placeholder_subst(self.ctx.db);
-                        self.ctx.db.impl_self_ty(impl_id).substitute(Interner, &subst)
+                        let args: crate::next_solver::GenericArgs<'_> =
+                            subst.to_nextsolver(interner);
+                        self.ctx
+                            .db
+                            .impl_self_ty(impl_id)
+                            .instantiate(interner, args)
+                            .to_chalk(interner)
                     }
                     ParamLoweringMode::Variable => TyBuilder::impl_self_ty(self.ctx.db, impl_id)
                         .fill_with_bound_vars(self.ctx.in_binders, 0)
-                        .build(),
+                        .build(DbInterner::conjure())
+                        .to_chalk(DbInterner::conjure()),
                 }
             }
             TypeNs::AdtSelfType(adt) => {
@@ -267,7 +279,9 @@ impl<'a, 'b> PathLoweringContext<'a, 'b> {
                         generics.bound_vars_subst(self.ctx.db, self.ctx.in_binders)
                     }
                 };
-                self.ctx.db.ty(adt.into()).substitute(Interner, &substs)
+                let interner = DbInterner::conjure();
+                let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+                self.ctx.db.ty(adt.into()).instantiate(interner, args).to_chalk(interner)
             }
 
             TypeNs::AdtId(it) => self.lower_path_inner(it.into(), infer_args),
@@ -537,7 +551,9 @@ impl<'a, 'b> PathLoweringContext<'a, 'b> {
             TyDefId::TypeAliasId(it) => it.into(),
         };
         let substs = self.substs_from_path_segment(generic_def, infer_args, None, false);
-        self.ctx.db.ty(typeable).substitute(Interner, &substs)
+        let interner = DbInterner::conjure();
+        let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+        self.ctx.db.ty(typeable).instantiate(interner, args).to_chalk(interner)
     }
 
     /// Collect generic arguments from a path into a `Substs`. See also
@@ -603,7 +619,7 @@ impl<'a, 'b> PathLoweringContext<'a, 'b> {
         explicit_self_ty: Option<Ty>,
         lowering_assoc_type_generics: bool,
     ) -> Substitution {
-        let mut lifetime_elision = self.ctx.lifetime_elision.clone();
+        let old_lifetime_elision = self.ctx.lifetime_elision.clone();
 
         if let Some(args) = self.current_or_prev_segment.args_and_bindings
             && args.parenthesized != GenericArgsParentheses::No
@@ -633,19 +649,21 @@ impl<'a, 'b> PathLoweringContext<'a, 'b> {
             }
 
             // `Fn()`-style generics are treated like functions for the purpose of lifetime elision.
-            lifetime_elision =
+            self.ctx.lifetime_elision =
                 LifetimeElisionKind::AnonymousCreateParameter { report_in_path: false };
         }
 
-        self.substs_from_args_and_bindings(
+        let result = self.substs_from_args_and_bindings(
             self.current_or_prev_segment.args_and_bindings,
             def,
             infer_args,
             explicit_self_ty,
             PathGenericsSource::Segment(self.current_segment_u32()),
             lowering_assoc_type_generics,
-            lifetime_elision,
-        )
+            self.ctx.lifetime_elision.clone(),
+        );
+        self.ctx.lifetime_elision = old_lifetime_elision;
+        result
     }
 
     pub(super) fn substs_from_args_and_bindings(
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/lower_nextsolver.rs b/src/tools/rust-analyzer/crates/hir-ty/src/lower_nextsolver.rs
index 0076446a958..84cd216b812 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/lower_nextsolver.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/lower_nextsolver.rs
@@ -19,9 +19,9 @@ use base_db::Crate;
 use either::Either;
 use hir_def::item_tree::FieldsShape;
 use hir_def::{
-    AdtId, AssocItemId, CallableDefId, ConstParamId, EnumVariantId, FunctionId, GenericDefId,
-    GenericParamId, ImplId, ItemContainerId, LocalFieldId, Lookup, StructId, TraitId, TypeAliasId,
-    TypeOrConstParamId, VariantId,
+    AdtId, AssocItemId, CallableDefId, ConstParamId, DefWithBodyId, EnumVariantId, FunctionId,
+    GenericDefId, GenericParamId, HasModule, ImplId, ItemContainerId, LocalFieldId, Lookup,
+    StructId, TraitId, TypeAliasId, TypeOrConstParamId, VariantId,
     expr_store::{
         ExpressionStore,
         path::{GenericArg, Path},
@@ -57,7 +57,7 @@ use triomphe::Arc;
 
 use crate::ValueTyDefId;
 use crate::{
-    FnAbi, ImplTraitId, Interner, ParamKind, TyDefId, TyLoweringDiagnostic,
+    FnAbi, ImplTraitId, Interner, ParamKind, TraitEnvironment, TyDefId, TyLoweringDiagnostic,
     TyLoweringDiagnosticKind,
     consteval_nextsolver::{intern_const_ref, path_to_const, unknown_const_as_generic},
     db::HirDatabase,
@@ -66,8 +66,10 @@ use crate::{
     next_solver::{
         AdtDef, AliasTy, Binder, BoundExistentialPredicates, BoundRegionKind, BoundTyKind,
         BoundVarKind, BoundVarKinds, Clause, Clauses, Const, DbInterner, EarlyBinder,
-        EarlyParamRegion, ErrorGuaranteed, GenericArgs, PolyFnSig, Predicate, Region, SolverDefId,
-        TraitPredicate, TraitRef, Ty, Tys, abi::Safety, mapping::ChalkToNextSolver,
+        EarlyParamRegion, ErrorGuaranteed, GenericArgs, ParamEnv, PolyFnSig, Predicate, Region,
+        SolverDefId, TraitPredicate, TraitRef, Ty, Tys,
+        abi::Safety,
+        mapping::{ChalkToNextSolver, convert_ty_for_result},
     },
 };
 
@@ -902,7 +904,7 @@ pub(crate) fn impl_trait_query<'db>(
     db: &'db dyn HirDatabase,
     impl_id: ImplId,
 ) -> Option<EarlyBinder<'db, TraitRef<'db>>> {
-    db.impl_trait_with_diagnostics_ns(impl_id).map(|it| it.0)
+    db.impl_trait_with_diagnostics(impl_id).map(|it| it.0)
 }
 
 pub(crate) fn impl_trait_with_diagnostics_query<'db>(
@@ -918,7 +920,7 @@ pub(crate) fn impl_trait_with_diagnostics_query<'db>(
         impl_id.into(),
         LifetimeElisionKind::AnonymousCreateParameter { report_in_path: true },
     );
-    let self_ty = db.impl_self_ty_ns(impl_id).skip_binder();
+    let self_ty = db.impl_self_ty(impl_id).skip_binder();
     let target_trait = impl_data.target_trait.as_ref()?;
     let trait_ref = EarlyBinder::bind(ctx.lower_trait_ref(target_trait, self_ty)?);
     Some((trait_ref, create_diagnostics(ctx.diagnostics)))
@@ -984,7 +986,7 @@ pub(crate) fn ty_query<'db>(db: &'db dyn HirDatabase, def: TyDefId) -> EarlyBind
             AdtDef::new(it, interner),
             GenericArgs::identity_for_item(interner, it.into()),
         )),
-        TyDefId::TypeAliasId(it) => db.type_for_type_alias_with_diagnostics_ns(it).0,
+        TyDefId::TypeAliasId(it) => db.type_for_type_alias_with_diagnostics(it).0,
     }
 }
 
@@ -1129,7 +1131,7 @@ pub(crate) fn impl_self_ty_query<'db>(
     db: &'db dyn HirDatabase,
     impl_id: ImplId,
 ) -> EarlyBinder<'db, Ty<'db>> {
-    db.impl_self_ty_with_diagnostics_ns(impl_id).0
+    db.impl_self_ty_with_diagnostics(impl_id).0
 }
 
 pub(crate) fn impl_self_ty_with_diagnostics_query<'db>(
@@ -1160,7 +1162,7 @@ pub(crate) fn impl_self_ty_with_diagnostics_cycle_result(
 }
 
 pub(crate) fn const_param_ty_query<'db>(db: &'db dyn HirDatabase, def: ConstParamId) -> Ty<'db> {
-    db.const_param_ty_with_diagnostics_ns(def).0
+    db.const_param_ty_with_diagnostics(def).0
 }
 
 // returns None if def is a type arg
@@ -1189,11 +1191,21 @@ pub(crate) fn const_param_ty_with_diagnostics_query<'db>(
     (ty, create_diagnostics(ctx.diagnostics))
 }
 
+pub(crate) fn const_param_ty_with_diagnostics_cycle_result<'db>(
+    db: &'db dyn HirDatabase,
+    _: crate::db::HirDatabaseData,
+    def: ConstParamId,
+) -> (Ty<'db>, Diagnostics) {
+    let resolver = def.parent().resolver(db);
+    let interner = DbInterner::new_with(db, Some(resolver.krate()), None);
+    (Ty::new_error(interner, ErrorGuaranteed), None)
+}
+
 pub(crate) fn field_types_query<'db>(
     db: &'db dyn HirDatabase,
     variant_id: VariantId,
 ) -> Arc<ArenaMap<LocalFieldId, EarlyBinder<'db, Ty<'db>>>> {
-    db.field_types_with_diagnostics_ns(variant_id).0
+    db.field_types_with_diagnostics(variant_id).0
 }
 
 /// Build the type of all specific fields of a struct or enum variant.
@@ -1355,6 +1367,18 @@ pub(crate) fn generic_predicates_for_param_cycle_result(
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct GenericPredicates<'db>(Option<Arc<[Clause<'db>]>>);
 
+impl<'db> GenericPredicates<'db> {
+    pub fn instantiate(
+        &self,
+        interner: DbInterner<'db>,
+        args: GenericArgs<'db>,
+    ) -> Option<impl Iterator<Item = Clause<'db>>> {
+        self.0
+            .as_ref()
+            .map(|it| EarlyBinder::bind(it.iter().copied()).iter_instantiated(interner, args))
+    }
+}
+
 impl<'db> ops::Deref for GenericPredicates<'db> {
     type Target = [Clause<'db>];
 
@@ -1363,6 +1387,122 @@ impl<'db> ops::Deref for GenericPredicates<'db> {
     }
 }
 
+pub(crate) fn trait_environment_for_body_query(
+    db: &dyn HirDatabase,
+    def: DefWithBodyId,
+) -> Arc<TraitEnvironment<'_>> {
+    let Some(def) = def.as_generic_def_id(db) else {
+        let krate = def.module(db).krate();
+        return TraitEnvironment::empty(krate);
+    };
+    db.trait_environment(def)
+}
+
+pub(crate) fn trait_environment_query<'db>(
+    db: &'db dyn HirDatabase,
+    def: GenericDefId,
+) -> Arc<TraitEnvironment<'db>> {
+    let generics = generics(db, def);
+    if generics.has_no_predicates() && generics.is_empty() {
+        return TraitEnvironment::empty(def.krate(db));
+    }
+
+    let interner = DbInterner::new_with(db, Some(def.krate(db)), None);
+    let resolver = def.resolver(db);
+    let mut ctx = TyLoweringContext::new(
+        db,
+        &resolver,
+        generics.store(),
+        def,
+        LifetimeElisionKind::AnonymousReportError,
+    );
+    let mut traits_in_scope = Vec::new();
+    let mut clauses = Vec::new();
+    for maybe_parent_generics in
+        std::iter::successors(Some(&generics), |generics| generics.parent_generics())
+    {
+        ctx.store = maybe_parent_generics.store();
+        for pred in maybe_parent_generics.where_predicates() {
+            for pred in ctx.lower_where_predicate(pred, false, &generics, PredicateFilter::All) {
+                if let rustc_type_ir::ClauseKind::Trait(tr) = pred.kind().skip_binder() {
+                    traits_in_scope
+                        .push((convert_ty_for_result(interner, tr.self_ty()), tr.def_id().0));
+                }
+                clauses.push(pred);
+            }
+        }
+    }
+
+    if let Some(trait_id) = def.assoc_trait_container(db) {
+        // add `Self: Trait<T1, T2, ...>` to the environment in trait
+        // function default implementations (and speculative code
+        // inside consts or type aliases)
+        cov_mark::hit!(trait_self_implements_self);
+        let trait_ref = TraitRef::identity(ctx.interner, trait_id.into());
+        let clause = Clause(Predicate::new(
+            ctx.interner,
+            Binder::dummy(rustc_type_ir::PredicateKind::Clause(rustc_type_ir::ClauseKind::Trait(
+                TraitPredicate { trait_ref, polarity: rustc_type_ir::PredicatePolarity::Positive },
+            ))),
+        ));
+        clauses.push(clause);
+    }
+
+    let explicitly_unsized_tys = ctx.unsized_types;
+
+    let sized_trait = LangItem::Sized.resolve_trait(db, resolver.krate());
+    if let Some(sized_trait) = sized_trait {
+        let (mut generics, mut def_id) =
+            (crate::next_solver::generics::generics(db, def.into()), def);
+        loop {
+            let self_idx = trait_self_param_idx(db, def_id);
+            for (idx, p) in generics.own_params.iter().enumerate() {
+                if let Some(self_idx) = self_idx
+                    && p.index() as usize == self_idx
+                {
+                    continue;
+                }
+                let GenericParamId::TypeParamId(param_id) = p.id else {
+                    continue;
+                };
+                let idx = idx as u32 + generics.parent_count as u32;
+                let param_ty = Ty::new_param(ctx.interner, param_id, idx, p.name.clone());
+                if explicitly_unsized_tys.contains(&param_ty) {
+                    continue;
+                }
+                let trait_ref = TraitRef::new_from_args(
+                    ctx.interner,
+                    sized_trait.into(),
+                    GenericArgs::new_from_iter(ctx.interner, [param_ty.into()]),
+                );
+                let clause = Clause(Predicate::new(
+                    ctx.interner,
+                    Binder::dummy(rustc_type_ir::PredicateKind::Clause(
+                        rustc_type_ir::ClauseKind::Trait(TraitPredicate {
+                            trait_ref,
+                            polarity: rustc_type_ir::PredicatePolarity::Positive,
+                        }),
+                    )),
+                ));
+                clauses.push(clause);
+            }
+
+            if let Some(g) = generics.parent {
+                generics = crate::next_solver::generics::generics(db, g.into());
+                def_id = g;
+            } else {
+                break;
+            }
+        }
+    }
+
+    let clauses = rustc_type_ir::elaborate::elaborate(ctx.interner, clauses);
+    let clauses = Clauses::new_from_iter(ctx.interner, clauses);
+    let env = ParamEnv { clauses };
+
+    TraitEnvironment::new(resolver.krate(), None, traits_in_scope.into_boxed_slice(), env)
+}
+
 #[derive(Copy, Clone, Debug)]
 pub(crate) enum PredicateFilter {
     SelfTrait,
@@ -1830,7 +1970,8 @@ fn named_associated_type_shorthand_candidates<'db, R>(
     let mut search = |t: TraitRef<'db>| -> Option<R> {
         let trait_id = t.def_id.0;
         let mut checked_traits = FxHashSet::default();
-        let mut check_trait = |trait_id: TraitId| {
+        let mut check_trait = |trait_ref: TraitRef<'db>| {
+            let trait_id = trait_ref.def_id.0;
             let name = &db.trait_signature(trait_id).name;
             tracing::debug!(?trait_id, ?name);
             if !checked_traits.insert(trait_id) {
@@ -1841,37 +1982,39 @@ fn named_associated_type_shorthand_candidates<'db, R>(
             tracing::debug!(?data.items);
             for (name, assoc_id) in &data.items {
                 if let &AssocItemId::TypeAliasId(alias) = assoc_id
-                    && let Some(ty) = check_alias(name, t, alias)
+                    && let Some(ty) = check_alias(name, trait_ref, alias)
                 {
                     return Some(ty);
                 }
             }
             None
         };
-        let mut stack: SmallVec<[_; 4]> = smallvec![trait_id];
-        while let Some(trait_def_id) = stack.pop() {
-            if let Some(alias) = check_trait(trait_def_id) {
+        let mut stack: SmallVec<[_; 4]> = smallvec![t];
+        while let Some(trait_ref) = stack.pop() {
+            if let Some(alias) = check_trait(trait_ref) {
                 return Some(alias);
             }
             for pred in generic_predicates_filtered_by(
                 db,
-                GenericDefId::TraitId(trait_def_id),
+                GenericDefId::TraitId(trait_ref.def_id.0),
                 PredicateFilter::SelfTrait,
                 // We are likely in the midst of lowering generic predicates of `def`.
                 // So, if we allow `pred == def` we might fall into an infinite recursion.
                 // Actually, we have already checked for the case `pred == def` above as we started
                 // with a stack including `trait_id`
-                |pred| pred != def && pred == GenericDefId::TraitId(trait_def_id),
+                |pred| pred != def && pred == GenericDefId::TraitId(trait_ref.def_id.0),
             )
             .0
             .deref()
             {
                 tracing::debug!(?pred);
-                let trait_id = match pred.kind().skip_binder() {
-                    rustc_type_ir::ClauseKind::Trait(pred) => pred.def_id(),
+                let sup_trait_ref = match pred.kind().skip_binder() {
+                    rustc_type_ir::ClauseKind::Trait(pred) => pred.trait_ref,
                     _ => continue,
                 };
-                stack.push(trait_id.0);
+                let sup_trait_ref =
+                    EarlyBinder::bind(sup_trait_ref).instantiate(interner, trait_ref.args);
+                stack.push(sup_trait_ref);
             }
             tracing::debug!(?stack);
         }
@@ -1881,7 +2024,7 @@ fn named_associated_type_shorthand_candidates<'db, R>(
 
     match res {
         TypeNs::SelfType(impl_id) => {
-            let trait_ref = db.impl_trait_ns(impl_id)?;
+            let trait_ref = db.impl_trait(impl_id)?;
 
             // FIXME(next-solver): same method in `lower` checks for impl or not
             // Is that needed here?
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/lower_nextsolver/path.rs b/src/tools/rust-analyzer/crates/hir-ty/src/lower_nextsolver/path.rs
index 7d6734303c4..0a9f34c9dab 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/lower_nextsolver/path.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/lower_nextsolver/path.rs
@@ -287,7 +287,7 @@ impl<'a, 'b, 'db> PathLoweringContext<'a, 'b, 'db> {
                     }
                 }
             }
-            TypeNs::SelfType(impl_id) => self.ctx.db.impl_self_ty_ns(impl_id).skip_binder(),
+            TypeNs::SelfType(impl_id) => self.ctx.db.impl_self_ty(impl_id).skip_binder(),
             TypeNs::AdtSelfType(adt) => {
                 let args = crate::next_solver::GenericArgs::identity_for_item(
                     self.ctx.interner,
@@ -616,7 +616,7 @@ impl<'a, 'b, 'db> PathLoweringContext<'a, 'b, 'db> {
         explicit_self_ty: Option<Ty<'db>>,
         lowering_assoc_type_generics: bool,
     ) -> crate::next_solver::GenericArgs<'db> {
-        let mut lifetime_elision = self.ctx.lifetime_elision.clone();
+        let old_lifetime_elision = self.ctx.lifetime_elision.clone();
 
         if let Some(args) = self.current_or_prev_segment.args_and_bindings
             && args.parenthesized != GenericArgsParentheses::No
@@ -646,19 +646,21 @@ impl<'a, 'b, 'db> PathLoweringContext<'a, 'b, 'db> {
             }
 
             // `Fn()`-style generics are treated like functions for the purpose of lifetime elision.
-            lifetime_elision =
+            self.ctx.lifetime_elision =
                 LifetimeElisionKind::AnonymousCreateParameter { report_in_path: false };
         }
 
-        self.substs_from_args_and_bindings(
+        let result = self.substs_from_args_and_bindings(
             self.current_or_prev_segment.args_and_bindings,
             def,
             infer_args,
             explicit_self_ty,
             PathGenericsSource::Segment(self.current_segment_u32()),
             lowering_assoc_type_generics,
-            lifetime_elision,
-        )
+            self.ctx.lifetime_elision.clone(),
+        );
+        self.ctx.lifetime_elision = old_lifetime_elision;
+        result
     }
 
     pub(super) fn substs_from_args_and_bindings(
@@ -915,22 +917,36 @@ impl<'a, 'b, 'db> PathLoweringContext<'a, 'b, 'db> {
                     binding.type_ref.as_ref().map_or(0, |_| 1) + binding.bounds.len(),
                 );
                 if let Some(type_ref) = binding.type_ref {
-                    match (&self.ctx.store[type_ref], self.ctx.impl_trait_mode.mode) {
-                        (TypeRef::ImplTrait(_), ImplTraitLoweringMode::Disallowed) => (),
-                        (_, ImplTraitLoweringMode::Disallowed | ImplTraitLoweringMode::Opaque) => {
-                            let ty = self.ctx.lower_ty(type_ref);
-                            let pred = Clause(Predicate::new(
-                                interner,
-                                Binder::dummy(rustc_type_ir::PredicateKind::Clause(
-                                    rustc_type_ir::ClauseKind::Projection(ProjectionPredicate {
-                                        projection_term,
-                                        term: ty.into(),
-                                    }),
-                                )),
-                            ));
-                            predicates.push(pred);
+                    let lifetime_elision =
+                        if args_and_bindings.parenthesized == GenericArgsParentheses::ParenSugar {
+                            // `Fn()`-style generics are elided like functions. This is `Output` (we lower to it in hir-def).
+                            LifetimeElisionKind::for_fn_ret(self.ctx.interner)
+                        } else {
+                            self.ctx.lifetime_elision.clone()
+                        };
+                    self.with_lifetime_elision(lifetime_elision, |this| {
+                        match (&this.ctx.store[type_ref], this.ctx.impl_trait_mode.mode) {
+                            (TypeRef::ImplTrait(_), ImplTraitLoweringMode::Disallowed) => (),
+                            (
+                                _,
+                                ImplTraitLoweringMode::Disallowed | ImplTraitLoweringMode::Opaque,
+                            ) => {
+                                let ty = this.ctx.lower_ty(type_ref);
+                                let pred = Clause(Predicate::new(
+                                    interner,
+                                    Binder::dummy(rustc_type_ir::PredicateKind::Clause(
+                                        rustc_type_ir::ClauseKind::Projection(
+                                            ProjectionPredicate {
+                                                projection_term,
+                                                term: ty.into(),
+                                            },
+                                        ),
+                                    )),
+                                ));
+                                predicates.push(pred);
+                            }
                         }
-                    }
+                    })
                 }
                 for bound in binding.bounds.iter() {
                     predicates.extend(self.ctx.lower_type_bound(
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/method_resolution.rs b/src/tools/rust-analyzer/crates/hir-ty/src/method_resolution.rs
index 7fa3d31fe5f..61d3091a0c1 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/method_resolution.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/method_resolution.rs
@@ -31,10 +31,13 @@ use crate::{
     infer::{Adjust, Adjustment, OverloadedDeref, PointerCast, unify::InferenceTable},
     lang_items::is_box,
     next_solver::{
-        self, SolverDefId,
-        fulfill::FulfillmentCtxt,
-        infer::DefineOpaqueTypes,
+        self, DbInterner, SolverDefId,
+        infer::{
+            DefineOpaqueTypes,
+            traits::{ObligationCause, PredicateObligation},
+        },
         mapping::{ChalkToNextSolver, NextSolverToChalk},
+        obligation_ctxt::ObligationCtxt,
     },
     primitive::{FloatTy, IntTy, UintTy},
     to_chalk_trait_id,
@@ -294,11 +297,12 @@ impl TraitImpls {
                     continue;
                 }
                 let target_trait = match db.impl_trait(impl_id) {
-                    Some(tr) => tr.skip_binders().hir_trait_id(),
+                    Some(tr) => tr.skip_binder().def_id.0,
                     None => continue,
                 };
-                let self_ty = db.impl_self_ty(impl_id);
-                let self_ty_fp = TyFingerprint::for_trait_impl(self_ty.skip_binders());
+                let interner = DbInterner::new_with(db, None, None);
+                let self_ty = db.impl_self_ty(impl_id).instantiate_identity().to_chalk(interner);
+                let self_ty_fp = TyFingerprint::for_trait_impl(&self_ty);
                 map.entry(target_trait).or_default().entry(self_ty_fp).or_default().push(impl_id);
             }
 
@@ -411,8 +415,8 @@ impl InherentImpls {
                     continue;
                 }
 
-                let self_ty = db.impl_self_ty(impl_id);
-                let self_ty = self_ty.skip_binders();
+                let interner = DbInterner::new_with(db, None, None);
+                let self_ty = &db.impl_self_ty(impl_id).instantiate_identity().to_chalk(interner);
 
                 match is_inherent_impl_coherent(db, def_map, impl_id, self_ty) {
                     true => {
@@ -542,7 +546,7 @@ pub fn def_crates(db: &dyn HirDatabase, ty: &Ty, cur_crate: Crate) -> Option<Sma
 pub(crate) fn lookup_method<'db>(
     db: &'db dyn HirDatabase,
     ty: &next_solver::Canonical<'db, crate::next_solver::Ty<'db>>,
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'db>>,
     traits_in_scope: &FxHashSet<TraitId>,
     visible_from_module: VisibleFromModule,
     name: &Name,
@@ -711,7 +715,7 @@ impl ReceiverAdjustments {
 pub(crate) fn iterate_method_candidates<'db, T>(
     ty: &next_solver::Canonical<'db, crate::next_solver::Ty<'db>>,
     db: &'db dyn HirDatabase,
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'db>>,
     traits_in_scope: &FxHashSet<TraitId>,
     visible_from_module: VisibleFromModule,
     name: Option<&Name>,
@@ -739,9 +743,9 @@ pub(crate) fn iterate_method_candidates<'db, T>(
     slot
 }
 
-pub fn lookup_impl_const(
-    db: &dyn HirDatabase,
-    env: Arc<TraitEnvironment>,
+pub fn lookup_impl_const<'db>(
+    db: &'db dyn HirDatabase,
+    env: Arc<TraitEnvironment<'db>>,
     const_id: ConstId,
     subs: Substitution,
 ) -> (ConstId, Substitution) {
@@ -767,9 +771,9 @@ pub fn lookup_impl_const(
 
 /// Checks if the self parameter of `Trait` method is the `dyn Trait` and we should
 /// call the method using the vtable.
-pub fn is_dyn_method(
-    db: &dyn HirDatabase,
-    _env: Arc<TraitEnvironment>,
+pub fn is_dyn_method<'db>(
+    db: &'db dyn HirDatabase,
+    _env: Arc<TraitEnvironment<'db>>,
     func: FunctionId,
     fn_subst: Substitution,
 ) -> Option<usize> {
@@ -809,9 +813,9 @@ pub fn is_dyn_method(
 /// Looks up the impl method that actually runs for the trait method `func`.
 ///
 /// Returns `func` if it's not a method defined in a trait or the lookup failed.
-pub(crate) fn lookup_impl_method_query(
-    db: &dyn HirDatabase,
-    env: Arc<TraitEnvironment>,
+pub(crate) fn lookup_impl_method_query<'db>(
+    db: &'db dyn HirDatabase,
+    env: Arc<TraitEnvironment<'db>>,
     func: FunctionId,
     fn_subst: Substitution,
 ) -> (FunctionId, Substitution) {
@@ -842,10 +846,10 @@ pub(crate) fn lookup_impl_method_query(
     )
 }
 
-fn lookup_impl_assoc_item_for_trait_ref(
+fn lookup_impl_assoc_item_for_trait_ref<'db>(
     trait_ref: TraitRef,
-    db: &dyn HirDatabase,
-    env: Arc<TraitEnvironment>,
+    db: &'db dyn HirDatabase,
+    env: Arc<TraitEnvironment<'db>>,
     name: &Name,
 ) -> Option<(AssocItemId, Substitution)> {
     let hir_trait_id = trait_ref.hir_trait_id();
@@ -894,10 +898,13 @@ fn find_matching_impl(
         table.run_in_snapshot(|table| {
             let impl_substs =
                 TyBuilder::subst_for_def(db, impl_, None).fill_with_inference_vars(table).build();
+            let args: crate::next_solver::GenericArgs<'_> =
+                impl_substs.to_nextsolver(table.interner);
             let trait_ref = db
                 .impl_trait(impl_)
                 .expect("non-trait method in find_matching_impl")
-                .substitute(Interner, &impl_substs);
+                .instantiate(table.interner, args)
+                .to_chalk(table.interner);
 
             if !table.unify(&trait_ref, &actual_trait_ref) {
                 return None;
@@ -907,10 +914,11 @@ fn find_matching_impl(
                 .into_iter()
                 .map(|b| -> Goal { b.cast(Interner) });
             for goal in wcs {
-                if table.try_obligation(goal.clone()).no_solution() {
+                let goal = goal.to_nextsolver(table.interner);
+                if table.try_obligation(goal).no_solution() {
                     return None;
                 }
-                table.register_obligation(goal.to_nextsolver(table.interner));
+                table.register_obligation(goal);
             }
             Some((
                 impl_.impl_items(db),
@@ -1014,7 +1022,9 @@ pub fn check_orphan_rules(db: &dyn HirDatabase, impl_: ImplId) -> bool {
     let local_crate = impl_.lookup(db).container.krate();
     let is_local = |tgt_crate| tgt_crate == local_crate;
 
-    let trait_ref = impl_trait.substitute(Interner, &substs);
+    let interner = DbInterner::new_with(db, None, None);
+    let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+    let trait_ref = impl_trait.instantiate(interner, args).to_chalk(interner);
     let trait_id = from_chalk_trait_id(trait_ref.trait_id);
     if is_local(trait_id.module(db).krate()) {
         // trait to be implemented is local
@@ -1063,7 +1073,7 @@ pub fn check_orphan_rules(db: &dyn HirDatabase, impl_: ImplId) -> bool {
 pub fn iterate_path_candidates<'db>(
     ty: &next_solver::Canonical<'db, crate::next_solver::Ty<'db>>,
     db: &'db dyn HirDatabase,
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'db>>,
     traits_in_scope: &FxHashSet<TraitId>,
     visible_from_module: VisibleFromModule,
     name: Option<&Name>,
@@ -1085,7 +1095,7 @@ pub fn iterate_path_candidates<'db>(
 pub fn iterate_method_candidates_dyn<'db>(
     ty: &next_solver::Canonical<'db, crate::next_solver::Ty<'db>>,
     db: &'db dyn HirDatabase,
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'db>>,
     traits_in_scope: &FxHashSet<TraitId>,
     visible_from_module: VisibleFromModule,
     name: Option<&Name>,
@@ -1347,7 +1357,7 @@ fn iterate_method_candidates_by_receiver<'db>(
 fn iterate_method_candidates_for_self_ty<'db>(
     self_ty: &next_solver::Canonical<'db, crate::next_solver::Ty<'db>>,
     db: &'db dyn HirDatabase,
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'db>>,
     traits_in_scope: &FxHashSet<TraitId>,
     visible_from_module: VisibleFromModule,
     name: Option<&Name>,
@@ -1395,7 +1405,7 @@ fn iterate_trait_method_candidates(
     let db = table.db;
 
     let canonical_self_ty = table.canonicalize(self_ty.clone().to_nextsolver(table.interner));
-    let TraitEnvironment { krate, .. } = *table.trait_env;
+    let krate = table.trait_env.krate;
 
     'traits: for &t in traits_in_scope {
         let data = db.trait_signature(t);
@@ -1635,7 +1645,6 @@ pub(crate) fn resolve_indexing_op<'db>(
     let ty = table.instantiate_canonical_ns(ty);
     let deref_chain = autoderef_method_receiver(table, ty);
     for (ty, adj) in deref_chain {
-        //let goal = generic_implements_goal_ns(db, &table.trait_env, index_trait, &ty);
         let goal = generic_implements_goal_ns(table, index_trait, ty);
         if !next_trait_solve_canonical_in_ctxt(&table.infer_ctxt, goal).no_solution() {
             return Some(adj);
@@ -1694,8 +1703,10 @@ fn is_valid_impl_method_candidate(
                 return IsValidCandidate::NotVisible;
             }
             let self_ty_matches = table.run_in_snapshot(|table| {
-                let expected_self_ty =
-                    TyBuilder::impl_self_ty(db, impl_id).fill_with_inference_vars(table).build();
+                let expected_self_ty = TyBuilder::impl_self_ty(db, impl_id)
+                    .fill_with_inference_vars(table)
+                    .build(DbInterner::conjure())
+                    .to_chalk(DbInterner::conjure());
                 table.unify(&expected_self_ty, self_ty)
             });
             if !self_ty_matches {
@@ -1741,9 +1752,13 @@ fn is_valid_trait_method_candidate(
                         .fill_with_inference_vars(table)
                         .build();
 
+                    let args: crate::next_solver::GenericArgs<'_> =
+                        fn_subst.to_nextsolver(table.interner);
                     let sig = db.callable_item_signature(fn_id.into());
-                    let expected_receiver =
-                        sig.map(|s| s.params()[0].clone()).substitute(Interner, &fn_subst);
+                    let expected_receiver = sig
+                        .map_bound(|s| s.skip_binder().inputs_and_output.as_slice()[0])
+                        .instantiate(table.interner, args)
+                        .to_chalk(table.interner);
 
                     // FIXME: Clean up this mess with some context struct like rustc's `ProbeContext`
                     let variance = match mode {
@@ -1754,7 +1769,7 @@ fn is_valid_trait_method_candidate(
                         .infer_ctxt
                         .at(
                             &next_solver::infer::traits::ObligationCause::dummy(),
-                            table.trait_env.env.to_nextsolver(table.interner),
+                            table.trait_env.env,
                         )
                         .relate(
                             DefineOpaqueTypes::No,
@@ -1767,12 +1782,10 @@ fn is_valid_trait_method_candidate(
                     };
 
                     if !infer_ok.obligations.is_empty() {
-                        let mut ctxt = FulfillmentCtxt::new(&table.infer_ctxt);
-                        for pred in infer_ok.into_obligations() {
-                            ctxt.register_predicate_obligation(&table.infer_ctxt, pred);
-                        }
+                        let mut ctxt = ObligationCtxt::new(&table.infer_ctxt);
+                        ctxt.register_obligations(infer_ok.into_obligations());
                         // FIXME: Are we doing this correctly? Probably better to follow rustc more closely.
-                        check_that!(ctxt.select_where_possible(&table.infer_ctxt).is_empty());
+                        check_that!(ctxt.select_where_possible().is_empty());
                     }
 
                     check_that!(table.unify(receiver_ty, &expected_receiver));
@@ -1815,9 +1828,11 @@ fn is_valid_impl_fn_candidate(
     }
     table.run_in_snapshot(|table| {
         let _p = tracing::info_span!("subst_for_def").entered();
-        let impl_subst =
-            TyBuilder::subst_for_def(db, impl_id, None).fill_with_inference_vars(table).build();
-        let expect_self_ty = db.impl_self_ty(impl_id).substitute(Interner, &impl_subst);
+        let impl_subst = table.infer_ctxt.fresh_args_for_item(impl_id.into());
+        let expect_self_ty = db
+            .impl_self_ty(impl_id)
+            .instantiate(table.interner, &impl_subst)
+            .to_chalk(table.interner);
 
         check_that!(table.unify(&expect_self_ty, self_ty));
 
@@ -1825,65 +1840,49 @@ fn is_valid_impl_fn_candidate(
             let _p = tracing::info_span!("check_receiver_ty").entered();
             check_that!(data.has_self_param());
 
-            let fn_subst = TyBuilder::subst_for_def(db, fn_id, Some(impl_subst.clone()))
-                .fill_with_inference_vars(table)
-                .build();
+            let fn_subst: crate::Substitution =
+                table.infer_ctxt.fresh_args_for_item(fn_id.into()).to_chalk(table.interner);
 
+            let args: crate::next_solver::GenericArgs<'_> = fn_subst.to_nextsolver(table.interner);
             let sig = db.callable_item_signature(fn_id.into());
-            let expected_receiver =
-                sig.map(|s| s.params()[0].clone()).substitute(Interner, &fn_subst);
+            let expected_receiver = sig
+                .map_bound(|s| s.skip_binder().inputs_and_output.as_slice()[0])
+                .instantiate(table.interner, args)
+                .to_chalk(table.interner);
 
             check_that!(table.unify(receiver_ty, &expected_receiver));
         }
 
         // We need to consider the bounds on the impl to distinguish functions of the same name
         // for a type.
-        let predicates = db.generic_predicates(impl_id.into());
-        let goals = predicates.iter().map(|p| {
-            let (p, b) = p
-                .clone()
-                .substitute(Interner, &impl_subst)
-                // Skipping the inner binders is ok, as we don't handle quantified where
-                // clauses yet.
-                .into_value_and_skipped_binders();
-            stdx::always!(b.len(Interner) == 0);
-
-            p.cast::<Goal>(Interner)
-        });
-
-        for goal in goals.clone() {
-            match table.solve_obligation(goal) {
-                Ok(_) => {}
-                Err(_) => {
-                    return IsValidCandidate::No;
-                }
-            }
-        }
+        let predicates = db.generic_predicates_ns(impl_id.into());
+        let Some(predicates) = predicates.instantiate(table.interner, impl_subst) else {
+            return IsValidCandidate::Yes;
+        };
 
-        for goal in goals {
-            if table.try_obligation(goal).no_solution() {
-                return IsValidCandidate::No;
-            }
-        }
+        let mut ctxt = ObligationCtxt::new(&table.infer_ctxt);
 
-        IsValidCandidate::Yes
-    })
-}
+        ctxt.register_obligations(predicates.into_iter().map(|p| {
+            PredicateObligation::new(
+                table.interner,
+                ObligationCause::new(),
+                table.trait_env.env,
+                p.0,
+            )
+        }));
 
-pub fn implements_trait(
-    ty: &Canonical<Ty>,
-    db: &dyn HirDatabase,
-    env: &TraitEnvironment,
-    trait_: TraitId,
-) -> bool {
-    let goal = generic_implements_goal(db, env, trait_, ty);
-    !db.trait_solve(env.krate, env.block, goal.cast(Interner)).no_solution()
+        if ctxt.select_where_possible().is_empty() {
+            IsValidCandidate::Yes
+        } else {
+            IsValidCandidate::No
+        }
+    })
 }
 
-pub fn implements_trait_unique(
+pub fn implements_trait_unique<'db>(
     ty: &Canonical<Ty>,
-    db: &dyn HirDatabase,
-    env: &TraitEnvironment,
+    db: &'db dyn HirDatabase,
+    env: &TraitEnvironment<'db>,
     trait_: TraitId,
 ) -> bool {
     let goal = generic_implements_goal(db, env, trait_, ty);
@@ -1891,11 +1890,11 @@ pub fn implements_trait_unique(
 }
 
 /// This creates Substs for a trait with the given Self type and type variables
-/// for all other parameters, to query Chalk with it.
+/// for all other parameters, to query next solver with it.
 #[tracing::instrument(skip_all)]
-fn generic_implements_goal(
-    db: &dyn HirDatabase,
-    env: &TraitEnvironment,
+fn generic_implements_goal<'db>(
+    db: &'db dyn HirDatabase,
+    env: &TraitEnvironment<'db>,
     trait_: TraitId,
     self_ty: &Canonical<Ty>,
 ) -> Canonical<InEnvironment<super::DomainGoal>> {
@@ -1917,7 +1916,10 @@ fn generic_implements_goal(
     let binders = CanonicalVarKinds::from_iter(Interner, kinds);
 
     let obligation = trait_ref.cast(Interner);
-    let value = InEnvironment::new(&env.env, obligation);
+    let value = InEnvironment::new(
+        &env.env.to_chalk(DbInterner::new_with(db, Some(env.krate), env.block)),
+        obligation,
+    );
     Canonical { binders, value }
 }
 
@@ -1934,11 +1936,7 @@ fn generic_implements_goal_ns<'db>(
     let trait_ref =
         rustc_type_ir::TraitRef::new_from_args(table.infer_ctxt.interner, trait_.into(), args)
             .with_replaced_self_ty(table.infer_ctxt.interner, self_ty);
-    let goal = next_solver::Goal::new(
-        table.infer_ctxt.interner,
-        table.trait_env.env.to_nextsolver(table.infer_ctxt.interner),
-        trait_ref,
-    );
+    let goal = next_solver::Goal::new(table.infer_ctxt.interner, table.trait_env.env, trait_ref);
 
     table.canonicalize(goal)
 }
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/mir/eval.rs b/src/tools/rust-analyzer/crates/hir-ty/src/mir/eval.rs
index fc7d97fff46..c93165a04c0 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/mir/eval.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/mir/eval.rs
@@ -165,7 +165,7 @@ enum MirOrDynIndex {
 
 pub struct Evaluator<'a> {
     db: &'a dyn HirDatabase,
-    trait_env: Arc<TraitEnvironment>,
+    trait_env: Arc<TraitEnvironment<'a>>,
     target_data_layout: Arc<TargetDataLayout>,
     stack: Vec<u8>,
     heap: Vec<u8>,
@@ -432,9 +432,12 @@ impl MirEvalError {
                 let self_ = match func.lookup(db).container {
                     ItemContainerId::ImplId(impl_id) => Some({
                         let generics = crate::generics::generics(db, impl_id.into());
+                        let interner = DbInterner::new_with(db, None, None);
                         let substs = generics.placeholder_subst(db);
+                        let args: crate::next_solver::GenericArgs<'_> =
+                            substs.to_nextsolver(interner);
                         db.impl_self_ty(impl_id)
-                            .substitute(Interner, &substs)
+                            .instantiate(interner, args)
                             .display(db, display_target)
                             .to_string()
                     }),
@@ -582,8 +585,8 @@ impl MirOutput {
     }
 }
 
-pub fn interpret_mir(
-    db: &dyn HirDatabase,
+pub fn interpret_mir<'db>(
+    db: &'db dyn HirDatabase,
     body: Arc<MirBody>,
     // FIXME: This is workaround. Ideally, const generics should have a separate body (issue #7434), but now
     // they share their body with their parent, so in MIR lowering we have locals of the parent body, which
@@ -591,7 +594,7 @@ pub fn interpret_mir(
     // a zero size, hoping that they are all outside of our current body. Even without a fix for #7434, we can
     // (and probably should) do better here, for example by excluding bindings outside of the target expression.
     assert_placeholder_ty_is_unused: bool,
-    trait_env: Option<Arc<TraitEnvironment>>,
+    trait_env: Option<Arc<TraitEnvironment<'db>>>,
 ) -> Result<(Result<Const>, MirOutput)> {
     let ty = body.locals[return_slot()].ty.clone();
     let mut evaluator = Evaluator::new(db, body.owner, assert_placeholder_ty_is_unused, trait_env)?;
@@ -632,11 +635,11 @@ const EXECUTION_LIMIT: usize = 10_000_000;
 
 impl<'db> Evaluator<'db> {
     pub fn new(
-        db: &dyn HirDatabase,
+        db: &'db dyn HirDatabase,
         owner: DefWithBodyId,
         assert_placeholder_ty_is_unused: bool,
-        trait_env: Option<Arc<TraitEnvironment>>,
-    ) -> Result<Evaluator<'_>> {
+        trait_env: Option<Arc<TraitEnvironment<'db>>>,
+    ) -> Result<Evaluator<'db>> {
         let crate_id = owner.module(db).krate();
         let target_data_layout = match db.target_data_layout(crate_id) {
             Ok(target_data_layout) => target_data_layout,
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/mir/eval/shim.rs b/src/tools/rust-analyzer/crates/hir-ty/src/mir/eval/shim.rs
index 38480493048..40d76bf42e9 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/mir/eval/shim.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/mir/eval/shim.rs
@@ -14,6 +14,7 @@ use hir_expand::name::Name;
 use intern::{Symbol, sym};
 use stdx::never;
 
+use crate::next_solver::mapping::NextSolverToChalk;
 use crate::{
     DropGlue,
     display::DisplayTarget,
@@ -1371,9 +1372,8 @@ impl Evaluator<'_> {
                     result = (l as i8).cmp(&(r as i8));
                 }
                 if let Some(e) = LangItem::Ordering.resolve_enum(self.db, self.crate_id) {
-                    let ty = self.db.ty(e.into());
-                    let r = self
-                        .compute_discriminant(ty.skip_binders().clone(), &[result as i8 as u8])?;
+                    let ty = self.db.ty(e.into()).skip_binder().to_chalk(interner);
+                    let r = self.compute_discriminant(ty.clone(), &[result as i8 as u8])?;
                     destination.write_from_bytes(self, &r.to_le_bytes()[0..destination.size])?;
                     Ok(())
                 } else {
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/mir/lower.rs b/src/tools/rust-analyzer/crates/hir-ty/src/mir/lower.rs
index 50e416a66a6..3e44e8c68dd 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/mir/lower.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/mir/lower.rs
@@ -43,7 +43,10 @@ use crate::{
         Terminator, TerminatorKind, TupleFieldId, Ty, UnOp, VariantId, intern_const_scalar,
         return_slot,
     },
-    next_solver::{DbInterner, mapping::ChalkToNextSolver},
+    next_solver::{
+        DbInterner,
+        mapping::{ChalkToNextSolver, NextSolverToChalk},
+    },
     static_lifetime,
     traits::FnTrait,
     utils::ClosureSubst,
@@ -82,7 +85,7 @@ struct MirLowerCtx<'db> {
     infer: &'db InferenceResult,
     resolver: Resolver<'db>,
     drop_scopes: Vec<DropScope>,
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'db>>,
 }
 
 // FIXME: Make this smaller, its stored in database queries
@@ -2207,8 +2210,13 @@ pub fn lower_to_mir(
             // otherwise it's an inline const, and has no parameter
             if let DefWithBodyId::FunctionId(fid) = owner {
                 let substs = TyBuilder::placeholder_subst(db, fid);
-                let callable_sig =
-                    db.callable_item_signature(fid.into()).substitute(Interner, &substs);
+                let interner = DbInterner::new_with(db, None, None);
+                let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+                let callable_sig = db
+                    .callable_item_signature(fid.into())
+                    .instantiate(interner, args)
+                    .skip_binder()
+                    .to_chalk(interner);
                 let mut params = callable_sig.params().iter();
                 let self_param = body.self_param.and_then(|id| Some((id, params.next()?.clone())));
                 break 'b ctx.lower_params_and_bindings(
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/mir/monomorphization.rs b/src/tools/rust-analyzer/crates/hir-ty/src/mir/monomorphization.rs
index 555b8785092..f293f38c769 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/mir/monomorphization.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/mir/monomorphization.rs
@@ -35,7 +35,7 @@ macro_rules! not_supported {
 
 struct Filler<'a> {
     db: &'a dyn HirDatabase,
-    trait_env: Arc<TraitEnvironment>,
+    trait_env: Arc<TraitEnvironment<'a>>,
     subst: &'a Substitution,
     generics: Option<Generics>,
 }
@@ -301,11 +301,11 @@ impl Filler<'_> {
     }
 }
 
-pub fn monomorphized_mir_body_query(
-    db: &dyn HirDatabase,
+pub fn monomorphized_mir_body_query<'db>(
+    db: &'db dyn HirDatabase,
     owner: DefWithBodyId,
     subst: Substitution,
-    trait_env: Arc<crate::TraitEnvironment>,
+    trait_env: Arc<crate::TraitEnvironment<'db>>,
 ) -> Result<Arc<MirBody>, MirLowerError> {
     let generics = owner.as_generic_def_id(db).map(|g_def| generics(db, g_def));
     let filler = &mut Filler { db, subst: &subst, trait_env, generics };
@@ -315,20 +315,20 @@ pub fn monomorphized_mir_body_query(
     Ok(Arc::new(body))
 }
 
-pub(crate) fn monomorphized_mir_body_cycle_result(
-    _db: &dyn HirDatabase,
+pub(crate) fn monomorphized_mir_body_cycle_result<'db>(
+    _db: &'db dyn HirDatabase,
     _: DefWithBodyId,
     _: Substitution,
-    _: Arc<crate::TraitEnvironment>,
+    _: Arc<crate::TraitEnvironment<'db>>,
 ) -> Result<Arc<MirBody>, MirLowerError> {
     Err(MirLowerError::Loop)
 }
 
-pub fn monomorphized_mir_body_for_closure_query(
-    db: &dyn HirDatabase,
+pub fn monomorphized_mir_body_for_closure_query<'db>(
+    db: &'db dyn HirDatabase,
     closure: InternedClosureId,
     subst: Substitution,
-    trait_env: Arc<crate::TraitEnvironment>,
+    trait_env: Arc<crate::TraitEnvironment<'db>>,
 ) -> Result<Arc<MirBody>, MirLowerError> {
     let InternedClosure(owner, _) = db.lookup_intern_closure(closure);
     let generics = owner.as_generic_def_id(db).map(|g_def| generics(db, g_def));
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/next_solver.rs b/src/tools/rust-analyzer/crates/hir-ty/src/next_solver.rs
index 073a02908de..ab167e88af2 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/next_solver.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/next_solver.rs
@@ -13,7 +13,7 @@ pub(crate) mod inspect;
 pub mod interner;
 mod ir_print;
 pub mod mapping;
-mod normalize;
+pub mod normalize;
 pub mod obligation_ctxt;
 mod opaques;
 pub mod predicate;
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/interner.rs b/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/interner.rs
index 9cf56bef957..b72504a19cf 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/interner.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/interner.rs
@@ -1091,23 +1091,21 @@ impl<'db> rustc_type_ir::Interner for DbInterner<'db> {
                     ItemContainerId::ImplId(it) => it,
                     _ => panic!("assoc ty value should be in impl"),
                 };
-                self.db().ty_ns(id.into())
+                self.db().ty(id.into())
             }
-            SolverDefId::AdtId(id) => self.db().ty_ns(id.into()),
+            SolverDefId::AdtId(id) => self.db().ty(id.into()),
             // FIXME(next-solver): This uses the types of `query mir_borrowck` in rustc.
             //
             // We currently always use the type from HIR typeck which ignores regions. This
             // should be fine.
             SolverDefId::InternedOpaqueTyId(_) => self.type_of_opaque_hir_typeck(def_id),
-            SolverDefId::FunctionId(id) => self.db.value_ty_ns(id.into()).unwrap(),
+            SolverDefId::FunctionId(id) => self.db.value_ty(id.into()).unwrap(),
             SolverDefId::Ctor(id) => {
                 let id = match id {
                     Ctor::Struct(id) => id.into(),
                     Ctor::Enum(id) => id.into(),
                 };
-                self.db
-                    .value_ty_ns(id)
-                    .expect("`SolverDefId::Ctor` should have a function-like ctor")
+                self.db.value_ty(id).expect("`SolverDefId::Ctor` should have a function-like ctor")
             }
             _ => panic!("Unexpected def_id `{def_id:?}` provided for `type_of`"),
         }
@@ -1227,7 +1225,7 @@ impl<'db> rustc_type_ir::Interner for DbInterner<'db> {
         self,
         def_id: Self::FunctionId,
     ) -> EarlyBinder<Self, rustc_type_ir::Binder<Self, rustc_type_ir::FnSig<Self>>> {
-        self.db().callable_item_signature_ns(def_id.0)
+        self.db().callable_item_signature(def_id.0)
     }
 
     fn coroutine_movability(self, def_id: Self::CoroutineId) -> rustc_ast_ir::Movability {
@@ -1322,7 +1320,7 @@ impl<'db> rustc_type_ir::Interner for DbInterner<'db> {
         self,
         def_id: Self::DefId,
     ) -> EarlyBinder<Self, impl IntoIterator<Item = Self::Clause>> {
-        let predicates = self.db().generic_predicates_without_parent_ns(def_id.try_into().unwrap());
+        let predicates = self.db().generic_predicates_without_parent(def_id.try_into().unwrap());
         let predicates: Vec<_> = predicates.iter().cloned().collect();
         EarlyBinder::bind(predicates.into_iter())
     }
@@ -1396,7 +1394,7 @@ impl<'db> rustc_type_ir::Interner for DbInterner<'db> {
         self,
         impl_id: Self::ImplId,
     ) -> EarlyBinder<Self, impl IntoIterator<Item = Self::Clause>> {
-        let trait_ref = self.db().impl_trait_ns(impl_id.0).expect("expected an impl of trait");
+        let trait_ref = self.db().impl_trait(impl_id.0).expect("expected an impl of trait");
         trait_ref.map_bound(|trait_ref| {
             let clause: Clause<'_> = trait_ref.upcast(self);
             Clauses::new_from_iter(
@@ -1635,7 +1633,7 @@ impl<'db> rustc_type_ir::Interner for DbInterner<'db> {
                 |impls| {
                     for i in impls.for_trait(trait_) {
                         use rustc_type_ir::TypeVisitable;
-                        let contains_errors = self.db().impl_trait_ns(i).map_or(false, |b| {
+                        let contains_errors = self.db().impl_trait(i).map_or(false, |b| {
                             b.skip_binder().visit_with(&mut ContainsTypeErrors).is_break()
                         });
                         if contains_errors {
@@ -1658,7 +1656,7 @@ impl<'db> rustc_type_ir::Interner for DbInterner<'db> {
                     for fp in fps {
                         for i in impls.for_trait_and_self_ty(trait_, *fp) {
                             use rustc_type_ir::TypeVisitable;
-                            let contains_errors = self.db().impl_trait_ns(i).map_or(false, |b| {
+                            let contains_errors = self.db().impl_trait(i).map_or(false, |b| {
                                 b.skip_binder().visit_with(&mut ContainsTypeErrors).is_break()
                             });
                             if contains_errors {
@@ -1704,7 +1702,7 @@ impl<'db> rustc_type_ir::Interner for DbInterner<'db> {
         impl_id: Self::ImplId,
     ) -> EarlyBinder<Self, rustc_type_ir::TraitRef<Self>> {
         let db = self.db();
-        db.impl_trait_ns(impl_id.0)
+        db.impl_trait(impl_id.0)
             // ImplIds for impls where the trait ref can't be resolved should never reach trait solving
             .expect("invalid impl passed to trait solver")
     }
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/mapping.rs b/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/mapping.rs
index b24b996b092..f3f74f67c04 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/mapping.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/mapping.rs
@@ -575,6 +575,17 @@ impl<
     }
 }
 
+impl<'db, T: NextSolverToChalk<'db, U>, U: HasInterner<Interner = Interner>>
+    NextSolverToChalk<'db, chalk_ir::Binders<U>> for rustc_type_ir::Binder<DbInterner<'db>, T>
+{
+    fn to_chalk(self, interner: DbInterner<'db>) -> chalk_ir::Binders<U> {
+        chalk_ir::Binders::new(
+            self.bound_vars().to_chalk(interner),
+            self.skip_binder().to_chalk(interner),
+        )
+    }
+}
+
 impl<'db> ChalkToNextSolver<'db, BoundVarKinds> for chalk_ir::VariableKinds<Interner> {
     fn to_nextsolver(&self, interner: DbInterner<'db>) -> BoundVarKinds {
         BoundVarKinds::new_from_iter(
@@ -584,6 +595,12 @@ impl<'db> ChalkToNextSolver<'db, BoundVarKinds> for chalk_ir::VariableKinds<Inte
     }
 }
 
+impl<'db> NextSolverToChalk<'db, chalk_ir::VariableKinds<Interner>> for BoundVarKinds {
+    fn to_chalk(self, interner: DbInterner<'db>) -> chalk_ir::VariableKinds<Interner> {
+        chalk_ir::VariableKinds::from_iter(Interner, self.iter().map(|v| v.to_chalk(interner)))
+    }
+}
+
 impl<'db> ChalkToNextSolver<'db, BoundVarKind> for chalk_ir::VariableKind<Interner> {
     fn to_nextsolver(&self, interner: DbInterner<'db>) -> BoundVarKind {
         match self {
@@ -594,6 +611,18 @@ impl<'db> ChalkToNextSolver<'db, BoundVarKind> for chalk_ir::VariableKind<Intern
     }
 }
 
+impl<'db> NextSolverToChalk<'db, chalk_ir::VariableKind<Interner>> for BoundVarKind {
+    fn to_chalk(self, interner: DbInterner<'db>) -> chalk_ir::VariableKind<Interner> {
+        match self {
+            BoundVarKind::Ty(_) => chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General),
+            BoundVarKind::Region(_) => chalk_ir::VariableKind::Lifetime,
+            BoundVarKind::Const => {
+                chalk_ir::VariableKind::Const(chalk_ir::TyKind::Error.intern(Interner))
+            }
+        }
+    }
+}
+
 impl<'db> ChalkToNextSolver<'db, GenericArg<'db>> for chalk_ir::GenericArg<Interner> {
     fn to_nextsolver(&self, interner: DbInterner<'db>) -> GenericArg<'db> {
         match self.data(Interner) {
@@ -1233,6 +1262,22 @@ where
     }
 }
 
+impl<'db> NextSolverToChalk<'db, crate::CallableSig> for rustc_type_ir::FnSig<DbInterner<'db>> {
+    fn to_chalk(self, interner: DbInterner<'db>) -> crate::CallableSig {
+        crate::CallableSig {
+            abi: self.abi,
+            is_varargs: self.c_variadic,
+            safety: match self.safety {
+                super::abi::Safety::Safe => chalk_ir::Safety::Safe,
+                super::abi::Safety::Unsafe => chalk_ir::Safety::Unsafe,
+            },
+            params_and_return: triomphe::Arc::from_iter(
+                self.inputs_and_output.iter().map(|ty| convert_ty_for_result(interner, ty)),
+            ),
+        }
+    }
+}
+
 pub fn convert_canonical_args_for_result<'db>(
     interner: DbInterner<'db>,
     args: Canonical<'db, Vec<GenericArg<'db>>>,
@@ -1266,7 +1311,7 @@ pub fn convert_args_for_result<'db>(
     Substitution::from_iter(Interner, substs)
 }
 
-pub(crate) fn convert_ty_for_result<'db>(interner: DbInterner<'db>, ty: Ty<'db>) -> crate::Ty {
+pub fn convert_ty_for_result<'db>(interner: DbInterner<'db>, ty: Ty<'db>) -> crate::Ty {
     use crate::{Scalar, TyKind};
     use chalk_ir::{FloatTy, IntTy, UintTy};
     match ty.kind() {
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/region.rs b/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/region.rs
index d6214d99156..0bfd2b8003d 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/region.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/region.rs
@@ -15,7 +15,7 @@ use super::{
     interner::{BoundVarKind, DbInterner, Placeholder},
 };
 
-type RegionKind<'db> = rustc_type_ir::RegionKind<DbInterner<'db>>;
+pub type RegionKind<'db> = rustc_type_ir::RegionKind<DbInterner<'db>>;
 
 #[salsa::interned(constructor = new_, debug)]
 pub struct Region<'db> {
@@ -53,6 +53,10 @@ impl<'db> Region<'db> {
         Region::new(interner, RegionKind::ReVar(v))
     }
 
+    pub fn new_erased(interner: DbInterner<'db>) -> Region<'db> {
+        Region::new(interner, RegionKind::ReErased)
+    }
+
     pub fn is_placeholder(&self) -> bool {
         matches!(self.inner(), RegionKind::RePlaceholder(..))
     }
@@ -61,6 +65,10 @@ impl<'db> Region<'db> {
         matches!(self.inner(), RegionKind::ReStatic)
     }
 
+    pub fn is_var(&self) -> bool {
+        matches!(self.inner(), RegionKind::ReVar(_))
+    }
+
     pub fn error(interner: DbInterner<'db>) -> Self {
         Region::new(interner, RegionKind::ReError(ErrorGuaranteed))
     }
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/solver.rs b/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/solver.rs
index 946e57e6cb7..a161423da4d 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/solver.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/solver.rs
@@ -156,16 +156,16 @@ impl<'db> SolverDelegate for SolverContext<'db> {
             SolverDefId::TypeAliasId(id) => id,
             _ => panic!("Unexpected SolverDefId"),
         };
-        let trait_ref = self
+        let trait_ = self
             .0
             .interner
             .db()
             .impl_trait(impl_id.0)
             // ImplIds for impls where the trait ref can't be resolved should never reach solver
             .expect("invalid impl passed to next-solver")
-            .into_value_and_skipped_binders()
+            .skip_binder()
+            .def_id
             .0;
-        let trait_ = trait_ref.hir_trait_id();
         let trait_data = trait_.trait_items(self.0.interner.db());
         let id =
             impl_id.0.impl_items(self.0.interner.db()).items.iter().find_map(|item| -> Option<_> {
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/ty.rs b/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/ty.rs
index 70139e86669..a25996ab485 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/ty.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/next_solver/ty.rs
@@ -7,6 +7,7 @@ use hir_def::{GenericDefId, TypeOrConstParamId, TypeParamId};
 use intern::{Interned, Symbol, sym};
 use rustc_abi::{Float, Integer, Size};
 use rustc_ast_ir::{Mutability, try_visit, visit::VisitorResult};
+use rustc_type_ir::TyVid;
 use rustc_type_ir::{
     BoundVar, ClosureKind, CollectAndApply, FlagComputation, Flags, FloatTy, FloatVid, InferTy,
     IntTy, IntVid, Interner, TypeFoldable, TypeSuperFoldable, TypeSuperVisitable, TypeVisitable,
@@ -336,6 +337,14 @@ impl<'db> Ty<'db> {
         matches!(self.kind(), TyKind::Tuple(tys) if tys.inner().is_empty())
     }
 
+    #[inline]
+    pub fn ty_vid(self) -> Option<TyVid> {
+        match self.kind() {
+            TyKind::Infer(rustc_type_ir::TyVar(vid)) => Some(vid),
+            _ => None,
+        }
+    }
+
     /// Given a `fn` type, returns an equivalent `unsafe fn` type;
     /// that is, a `fn` type that is equivalent in every way for being
     /// unsafe.
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/tests/incremental.rs b/src/tools/rust-analyzer/crates/hir-ty/src/tests/incremental.rs
index c0b930e5e12..8587c13e87f 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/tests/incremental.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/tests/incremental.rs
@@ -511,7 +511,6 @@ impl SomeStruct {
                 "struct_signature_shim",
                 "struct_signature_with_source_map_shim",
                 "attrs_shim",
-                "type_for_adt_tracked",
             ]
         "#]],
     );
@@ -609,9 +608,6 @@ fn main() {
                 "trait_impls_in_crate_shim",
                 "impl_trait_with_diagnostics_shim",
                 "impl_self_ty_with_diagnostics_shim",
-                "type_for_adt_tracked",
-                "impl_trait_with_diagnostics_ns_shim",
-                "impl_self_ty_with_diagnostics_ns_shim",
                 "generic_predicates_ns_shim",
                 "value_ty_shim",
                 "generic_predicates_shim",
@@ -700,8 +696,6 @@ fn main() {
                 "trait_impls_in_crate_shim",
                 "impl_trait_with_diagnostics_shim",
                 "impl_self_ty_with_diagnostics_shim",
-                "impl_trait_with_diagnostics_ns_shim",
-                "impl_self_ty_with_diagnostics_ns_shim",
                 "generic_predicates_ns_shim",
                 "generic_predicates_shim",
             ]
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/tests/method_resolution.rs b/src/tools/rust-analyzer/crates/hir-ty/src/tests/method_resolution.rs
index b14ce35aa99..2f8f6664756 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/tests/method_resolution.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/tests/method_resolution.rs
@@ -2050,10 +2050,10 @@ impl dyn Error + Send {
     /// Attempts to downcast the box to a concrete type.
     pub fn downcast<T: Error + 'static>(self: Box<Self>) -> Result<Box<T>, Box<dyn Error + Send>> {
         let err: Box<dyn Error> = self;
-                               // ^^^^ expected Box<dyn Error + '?>, got Box<dyn Error + Send + '?>
+                               // ^^^^ expected Box<dyn Error + '?>, got Box<dyn Error + Send + 'static>
                                // FIXME, type mismatch should not occur
         <dyn Error>::downcast(err).map_err(|_| loop {})
-      //^^^^^^^^^^^^^^^^^^^^^ type: fn downcast<{unknown}>(Box<dyn Error + '?>) -> Result<Box<{unknown}>, Box<dyn Error + '?>>
+      //^^^^^^^^^^^^^^^^^^^^^ type: fn downcast<{unknown}>(Box<dyn Error + 'static>) -> Result<Box<{unknown}>, Box<dyn Error + 'static>>
     }
 }
 "#,
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/tests/never_type.rs b/src/tools/rust-analyzer/crates/hir-ty/src/tests/never_type.rs
index af5290d7203..4d68179a88b 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/tests/never_type.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/tests/never_type.rs
@@ -14,8 +14,6 @@ fn test() {
     );
 }
 
-// FIXME(next-solver): The never type fallback implemented in r-a no longer works properly because of
-// `Coerce` predicates. We should reimplement fallback like rustc.
 #[test]
 fn infer_never2() {
     check_types(
@@ -26,7 +24,7 @@ fn test() {
     let a = gen();
     if false { a } else { loop {} };
     a;
-} //^ {unknown}
+} //^ !
 "#,
     );
 }
@@ -41,7 +39,7 @@ fn test() {
     let a = gen();
     if false { loop {} } else { a };
     a;
-  //^ {unknown}
+  //^ !
 }
 "#,
     );
@@ -56,7 +54,7 @@ enum Option<T> { None, Some(T) }
 fn test() {
     let a = if true { Option::None } else { Option::Some(return) };
     a;
-} //^ Option<{unknown}>
+} //^ Option<!>
 "#,
     );
 }
@@ -220,7 +218,7 @@ fn test(a: i32) {
         _ => loop {},
     };
     i;
-} //^ {unknown}
+} //^ !
 "#,
     );
 }
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/tests/regression.rs b/src/tools/rust-analyzer/crates/hir-ty/src/tests/regression.rs
index 2ba1e2341b2..00835aa0313 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/tests/regression.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/tests/regression.rs
@@ -632,7 +632,7 @@ fn issue_4053_diesel_where_clauses() {
             488..522 '{     ...     }': <SelectStatement<F, S, D, W, O, LOf, {unknown}, {unknown}> as BoxedDsl<DB>>::Output
             498..502 'self': SelectStatement<F, S, D, W, O, LOf, {unknown}, {unknown}>
             498..508 'self.order': O
-            498..515 'self.o...into()': dyn QueryFragment<DB> + '?
+            498..515 'self.o...into()': dyn QueryFragment<DB> + 'static
         "#]],
     );
 }
@@ -1951,7 +1951,7 @@ fn main() {
     Alias::Braced;
   //^^^^^^^^^^^^^ {unknown}
     let Alias::Braced = loop {};
-      //^^^^^^^^^^^^^ {unknown}
+      //^^^^^^^^^^^^^ !
   let Alias::Braced(..) = loop {};
     //^^^^^^^^^^^^^^^^^ Enum
 
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/tests/regression/new_solver.rs b/src/tools/rust-analyzer/crates/hir-ty/src/tests/regression/new_solver.rs
index ead79a8f5b9..adc35cc9bc1 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/tests/regression/new_solver.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/tests/regression/new_solver.rs
@@ -1,6 +1,6 @@
 use expect_test::expect;
 
-use crate::tests::{check_infer, check_no_mismatches};
+use crate::tests::{check_infer, check_no_mismatches, check_types};
 
 #[test]
 fn regression_20365() {
@@ -418,3 +418,57 @@ fn foo() {
         "#]],
     );
 }
+
+#[test]
+fn regression_19637() {
+    check_no_mismatches(
+        r#"
+//- minicore: coerce_unsized
+pub trait Any {}
+
+impl<T: 'static> Any for T {}
+
+pub trait Trait: Any {
+    type F;
+}
+
+pub struct TT {}
+
+impl Trait for TT {
+    type F = f32;
+}
+
+pub fn coercion(x: &mut dyn Any) -> &mut dyn Any {
+    x
+}
+
+fn main() {
+    let mut t = TT {};
+    let tt = &mut t as &mut dyn Trait<F = f32>;
+    let st = coercion(tt);
+}
+    "#,
+    );
+}
+
+#[test]
+fn double_into_iter() {
+    check_types(
+        r#"
+//- minicore: iterator
+
+fn intoiter_issue<A, B>(foo: A)
+where
+    A: IntoIterator<Item = B>,
+    B: IntoIterator<Item = usize>,
+{
+    for x in foo {
+    //  ^ B
+        for m in x {
+        //  ^ usize
+        }
+    }
+}
+"#,
+    );
+}
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/tests/traits.rs b/src/tools/rust-analyzer/crates/hir-ty/src/tests/traits.rs
index 41f8d4ed555..66faac09cc2 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/tests/traits.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/tests/traits.rs
@@ -1487,8 +1487,8 @@ fn test(x: Box<dyn Trait<u64>>, y: &dyn Trait<u64>) {
             268..269 'x': Box<dyn Trait<u64> + '?>
             275..276 'y': &'? (dyn Trait<u64> + '?)
             286..287 'z': Box<dyn Trait<u64> + '?>
-            290..293 'bar': fn bar() -> Box<dyn Trait<u64> + '?>
-            290..295 'bar()': Box<dyn Trait<u64> + '?>
+            290..293 'bar': fn bar() -> Box<dyn Trait<u64> + 'static>
+            290..295 'bar()': Box<dyn Trait<u64> + 'static>
             301..302 'x': Box<dyn Trait<u64> + '?>
             301..308 'x.foo()': u64
             314..315 'y': &'? (dyn Trait<u64> + '?)
@@ -1535,7 +1535,7 @@ fn test(s: S<u32, i32>) {
             251..252 's': S<u32, i32>
             267..289 '{     ...z(); }': ()
             273..274 's': S<u32, i32>
-            273..280 's.bar()': &'? (dyn Trait<u32, i32> + '?)
+            273..280 's.bar()': &'? (dyn Trait<u32, i32> + 'static)
             273..286 's.bar().baz()': (u32, i32)
         "#]],
     );
@@ -1568,8 +1568,8 @@ fn test(x: Trait, y: &Trait) -> u64 {
             106..107 'x': dyn Trait + '?
             113..114 'y': &'? (dyn Trait + '?)
             124..125 'z': dyn Trait + '?
-            128..131 'bar': fn bar() -> dyn Trait + '?
-            128..133 'bar()': dyn Trait + '?
+            128..131 'bar': fn bar() -> dyn Trait + 'static
+            128..133 'bar()': dyn Trait + 'static
             139..140 'x': dyn Trait + '?
             139..146 'x.foo()': u64
             152..153 'y': &'? (dyn Trait + '?)
@@ -1597,7 +1597,7 @@ fn main() {
             47..48 '_': &'? (dyn Fn(S) + '?)
             58..60 '{}': ()
             71..105 '{     ...()); }': ()
-            77..78 'f': fn f(&'? (dyn Fn(S) + '?))
+            77..78 'f': fn f(&'? (dyn Fn(S) + 'static))
             77..102 'f(&|nu...foo())': ()
             79..101 '&|numb....foo()': &'? impl Fn(S)
             80..101 '|numbe....foo()': impl Fn(S)
@@ -2952,7 +2952,7 @@ fn test(x: &dyn Foo) {
             34..36 '{}': ()
             46..47 'x': &'? (dyn Foo + '?)
             59..74 '{     foo(x); }': ()
-            65..68 'foo': fn foo(&'? (dyn Foo + '?))
+            65..68 'foo': fn foo(&'? (dyn Foo + 'static))
             65..71 'foo(x)': ()
             69..70 'x': &'? (dyn Foo + '?)
         "#]],
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/traits.rs b/src/tools/rust-analyzer/crates/hir-ty/src/traits.rs
index 8095d702be4..8ac152341e7 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/traits.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/traits.rs
@@ -1,4 +1,4 @@
-//! Trait solving using Chalk.
+//! Trait solving using next trait solver.
 
 use core::fmt;
 use std::hash::Hash;
@@ -25,7 +25,7 @@ use crate::{
     db::HirDatabase,
     infer::unify::InferenceTable,
     next_solver::{
-        DbInterner, GenericArg, Predicate, SolverContext, Span,
+        DbInterner, GenericArg, ParamEnv, Predicate, SolverContext, Span,
         infer::{DbInternerInferExt, InferCtxt},
         mapping::{ChalkToNextSolver, convert_canonical_args_for_result},
         util::mini_canonicalize,
@@ -39,21 +39,21 @@ use crate::{
 /// ```
 /// we assume that `T: Default`.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
-pub struct TraitEnvironment {
+pub struct TraitEnvironment<'db> {
     pub krate: Crate,
     pub block: Option<BlockId>,
     // FIXME make this a BTreeMap
     traits_from_clauses: Box<[(Ty, TraitId)]>,
-    pub env: chalk_ir::Environment<Interner>,
+    pub env: ParamEnv<'db>,
 }
 
-impl TraitEnvironment {
+impl<'db> TraitEnvironment<'db> {
     pub fn empty(krate: Crate) -> Arc<Self> {
         Arc::new(TraitEnvironment {
             krate,
             block: None,
             traits_from_clauses: Box::default(),
-            env: chalk_ir::Environment::new(Interner),
+            env: ParamEnv::empty(),
         })
     }
 
@@ -61,7 +61,7 @@ impl TraitEnvironment {
         krate: Crate,
         block: Option<BlockId>,
         traits_from_clauses: Box<[(Ty, TraitId)]>,
-        env: chalk_ir::Environment<Interner>,
+        env: ParamEnv<'db>,
     ) -> Arc<Self> {
         Arc::new(TraitEnvironment { krate, block, traits_from_clauses, env })
     }
@@ -78,10 +78,10 @@ impl TraitEnvironment {
     }
 }
 
-pub(crate) fn normalize_projection_query(
-    db: &dyn HirDatabase,
+pub(crate) fn normalize_projection_query<'db>(
+    db: &'db dyn HirDatabase,
     projection: ProjectionTy,
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'db>>,
 ) -> Ty {
     if projection.substitution.iter(Interner).any(|arg| {
         arg.ty(Interner)
@@ -128,7 +128,7 @@ fn identity_subst(
     chalk_ir::Canonical { binders, value: identity_subst }
 }
 
-/// Solve a trait goal using Chalk.
+/// Solve a trait goal using next trait solver.
 pub(crate) fn trait_solve_query(
     db: &dyn HirDatabase,
     krate: Crate,
@@ -325,7 +325,7 @@ pub fn next_trait_solve_canonical_in_ctxt<'db>(
     }
 }
 
-/// Solve a trait goal using Chalk.
+/// Solve a trait goal using next trait solver.
 pub fn next_trait_solve_in_ctxt<'db, 'a>(
     infer_ctxt: &'a InferCtxt<'db>,
     goal: crate::next_solver::Goal<'db, crate::next_solver::Predicate<'db>>,
diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/variance.rs b/src/tools/rust-analyzer/crates/hir-ty/src/variance.rs
index 8593dba301b..a17cf378270 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/variance.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/variance.rs
@@ -15,6 +15,8 @@
 
 use crate::db::HirDatabase;
 use crate::generics::{Generics, generics};
+use crate::next_solver::DbInterner;
+use crate::next_solver::mapping::{ChalkToNextSolver, NextSolverToChalk};
 use crate::{
     AliasTy, Const, ConstScalar, DynTyExt, GenericArg, GenericArgData, Interner, Lifetime,
     LifetimeData, Ty, TyKind,
@@ -238,14 +240,15 @@ impl Context<'_> {
             }
             GenericDefId::FunctionId(f) => {
                 let subst = self.generics.placeholder_subst(self.db);
-                self.add_constraints_from_sig(
-                    self.db
-                        .callable_item_signature(f.into())
-                        .substitute(Interner, &subst)
-                        .params_and_return
-                        .iter(),
-                    Variance::Covariant,
-                );
+                let interner = DbInterner::new_with(self.db, None, None);
+                let args: crate::next_solver::GenericArgs<'_> = subst.to_nextsolver(interner);
+                let sig = self
+                    .db
+                    .callable_item_signature(f.into())
+                    .instantiate(interner, args)
+                    .skip_binder()
+                    .to_chalk(interner);
+                self.add_constraints_from_sig(sig.params_and_return.iter(), Variance::Covariant);
             }
             _ => {}
         }
diff --git a/src/tools/rust-analyzer/crates/hir/src/display.rs b/src/tools/rust-analyzer/crates/hir/src/display.rs
index 833a9ef0306..2bf9bb85e50 100644
--- a/src/tools/rust-analyzer/crates/hir/src/display.rs
+++ b/src/tools/rust-analyzer/crates/hir/src/display.rs
@@ -24,7 +24,7 @@ use crate::{
     Adt, AsAssocItem, AssocItem, AssocItemContainer, Const, ConstParam, Crate, Enum,
     ExternCrateDecl, Field, Function, GenericParam, HasCrate, HasVisibility, Impl, LifetimeParam,
     Macro, Module, SelfParam, Static, Struct, StructKind, Trait, TraitRef, TupleField, TyBuilder,
-    Type, TypeAlias, TypeOrConstParam, TypeParam, Union, Variant,
+    Type, TypeAlias, TypeNs, TypeOrConstParam, TypeParam, Union, Variant,
 };
 
 impl HirDisplay for Function {
@@ -437,6 +437,12 @@ impl HirDisplay for Type<'_> {
     }
 }
 
+impl HirDisplay for TypeNs<'_> {
+    fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
+        self.ty.hir_fmt(f)
+    }
+}
+
 impl HirDisplay for ExternCrateDecl {
     fn hir_fmt(&self, f: &mut HirFormatter<'_>) -> Result<(), HirDisplayError> {
         write_visibility(self.module(f.db).id, self.visibility(f.db), f)?;
diff --git a/src/tools/rust-analyzer/crates/hir/src/lib.rs b/src/tools/rust-analyzer/crates/hir/src/lib.rs
index 17767955d47..4342624dd64 100644
--- a/src/tools/rust-analyzer/crates/hir/src/lib.rs
+++ b/src/tools/rust-analyzer/crates/hir/src/lib.rs
@@ -82,7 +82,9 @@ use hir_ty::{
     method_resolution,
     mir::{MutBorrowKind, interpret_mir},
     next_solver::{
-        ClauseKind, DbInterner, GenericArgs, infer::InferCtxt, mapping::ChalkToNextSolver,
+        ClauseKind, DbInterner, GenericArgs,
+        infer::InferCtxt,
+        mapping::{ChalkToNextSolver, NextSolverToChalk, convert_ty_for_result},
     },
     primitive::UintTy,
     traits::FnTrait,
@@ -863,10 +865,13 @@ impl Module {
                     .collect();
 
                 if !missing.is_empty() {
-                    let self_ty = db.impl_self_ty(impl_def.id).substitute(
-                        Interner,
-                        &hir_ty::generics::generics(db, impl_def.id.into()).placeholder_subst(db),
-                    );
+                    let interner = DbInterner::new_with(db, None, None);
+                    let args: crate::next_solver::GenericArgs<'_> =
+                        hir_ty::generics::generics(db, impl_def.id.into())
+                            .placeholder_subst(db)
+                            .to_nextsolver(interner);
+                    let self_ty =
+                        db.impl_self_ty(impl_def.id).instantiate(interner, args).to_chalk(interner);
                     let self_ty = if let TyKind::Alias(AliasTy::Projection(projection)) =
                         self_ty.kind(Interner)
                     {
@@ -1342,19 +1347,12 @@ impl Field {
         u32::from(self.id.into_raw()) as usize
     }
 
-    /// Returns the type as in the signature of the struct (i.e., with
-    /// placeholder types for type parameters). Only use this in the context of
-    /// the field definition.
-    pub fn ty<'db>(&self, db: &'db dyn HirDatabase) -> Type<'db> {
+    /// Returns the type as in the signature of the struct. Only use this in the
+    /// context of the field definition.
+    pub fn ty<'db>(&self, db: &'db dyn HirDatabase) -> TypeNs<'db> {
         let var_id = self.parent.into();
-        let generic_def_id: GenericDefId = match self.parent {
-            VariantDef::Struct(it) => it.id.into(),
-            VariantDef::Union(it) => it.id.into(),
-            VariantDef::Variant(it) => it.id.lookup(db).parent.into(),
-        };
-        let substs = TyBuilder::placeholder_subst(db, generic_def_id);
-        let ty = db.field_types(var_id)[self.id].clone().substitute(Interner, &substs);
-        Type::new(db, var_id, ty)
+        let ty = db.field_types_ns(var_id)[self.id].skip_binder();
+        TypeNs::new(db, var_id, ty)
     }
 
     // FIXME: Find better API to also handle const generics
@@ -1384,9 +1382,8 @@ impl Field {
     }
 
     pub fn layout(&self, db: &dyn HirDatabase) -> Result<Layout, LayoutError> {
-        let interner = DbInterner::new_with(db, None, None);
         db.layout_of_ty(
-            self.ty(db).ty.to_nextsolver(interner),
+            self.ty(db).ty,
             db.trait_environment(match hir_def::VariantId::from(self.parent) {
                 hir_def::VariantId::EnumVariantId(id) => {
                     GenericDefId::AdtId(id.lookup(db).parent.into())
@@ -1506,7 +1503,7 @@ impl<'db> InstantiatedStruct<'db> {
         let krate = self.inner.krate(db);
         let interner = DbInterner::new_with(db, Some(krate.base()), None);
 
-        let ty = db.ty_ns(self.inner.id.into());
+        let ty = db.ty(self.inner.id.into());
         TypeNs::new(db, self.inner.id, ty.instantiate(interner, self.args))
     }
 }
@@ -1666,7 +1663,7 @@ impl<'db> InstantiatedEnum<'db> {
         let krate = self.inner.krate(db);
         let interner = DbInterner::new_with(db, Some(krate.base()), None);
 
-        let ty = db.ty_ns(self.inner.id.into());
+        let ty = db.ty(self.inner.id.into());
         TypeNs::new(db, self.inner.id, ty.instantiate(interner, self.args))
     }
 }
@@ -1853,7 +1850,8 @@ impl Adt {
                     ParamKind::Lifetime => error_lifetime().cast(Interner),
                 }
             })
-            .build();
+            .build(DbInterner::conjure())
+            .to_chalk(DbInterner::conjure());
         Type::new(db, id, ty)
     }
 
@@ -2288,7 +2286,13 @@ impl Function {
     pub fn fn_ptr_type(self, db: &dyn HirDatabase) -> Type<'_> {
         let resolver = self.id.resolver(db);
         let substs = TyBuilder::placeholder_subst(db, self.id);
-        let callable_sig = db.callable_item_signature(self.id.into()).substitute(Interner, &substs);
+        let interner = DbInterner::new_with(db, None, None);
+        let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+        let callable_sig = db
+            .callable_item_signature(self.id.into())
+            .instantiate(interner, args)
+            .skip_binder()
+            .to_chalk(interner);
         let ty = TyKind::Function(callable_sig.to_fn_ptr()).intern(Interner);
         Type::new_with_resolver_inner(db, &resolver, ty)
     }
@@ -2297,8 +2301,14 @@ impl Function {
     pub fn ret_type(self, db: &dyn HirDatabase) -> Type<'_> {
         let resolver = self.id.resolver(db);
         let substs = TyBuilder::placeholder_subst(db, self.id);
-        let callable_sig = db.callable_item_signature(self.id.into()).substitute(Interner, &substs);
-        let ty = callable_sig.ret().clone();
+        let interner = DbInterner::new_with(db, None, None);
+        let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+        let ty = db
+            .callable_item_signature(self.id.into())
+            .instantiate(interner, args)
+            .skip_binder()
+            .output()
+            .to_chalk(interner);
         Type::new_with_resolver_inner(db, &resolver, ty)
     }
 
@@ -2327,8 +2337,14 @@ impl Function {
             parent_id.map(|id| TyBuilder::subst_for_def(db, id, None).fill(&mut filler).build());
         let substs = TyBuilder::subst_for_def(db, self.id, parent_substs).fill(&mut filler).build();
 
-        let callable_sig = db.callable_item_signature(self.id.into()).substitute(Interner, &substs);
-        let ty = callable_sig.ret().clone();
+        let interner = DbInterner::new_with(db, None, None);
+        let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+        let ty = db
+            .callable_item_signature(self.id.into())
+            .instantiate(interner, args)
+            .skip_binder()
+            .output()
+            .to_chalk(interner);
         Type::new_with_resolver_inner(db, &resolver, ty)
     }
 
@@ -2338,8 +2354,14 @@ impl Function {
         }
         let resolver = self.id.resolver(db);
         let substs = TyBuilder::placeholder_subst(db, self.id);
-        let callable_sig = db.callable_item_signature(self.id.into()).substitute(Interner, &substs);
-        let ret_ty = callable_sig.ret().clone();
+        let interner = DbInterner::new_with(db, None, None);
+        let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+        let ret_ty = db
+            .callable_item_signature(self.id.into())
+            .instantiate(interner, args)
+            .skip_binder()
+            .output()
+            .to_chalk(interner);
         for pred in ret_ty.impl_trait_bounds(db).into_iter().flatten() {
             if let WhereClause::AliasEq(output_eq) = pred.into_value_and_skipped_binders().0 {
                 return Type::new_with_resolver_inner(db, &resolver, output_eq.ty).into();
@@ -2359,7 +2381,13 @@ impl Function {
     pub fn assoc_fn_params(self, db: &dyn HirDatabase) -> Vec<Param<'_>> {
         let environment = db.trait_environment(self.id.into());
         let substs = TyBuilder::placeholder_subst(db, self.id);
-        let callable_sig = db.callable_item_signature(self.id.into()).substitute(Interner, &substs);
+        let interner = DbInterner::new_with(db, None, None);
+        let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+        let callable_sig = db
+            .callable_item_signature(self.id.into())
+            .instantiate(interner, args)
+            .skip_binder()
+            .to_chalk(interner);
         callable_sig
             .params()
             .iter()
@@ -2387,7 +2415,13 @@ impl Function {
     pub fn params_without_self(self, db: &dyn HirDatabase) -> Vec<Param<'_>> {
         let environment = db.trait_environment(self.id.into());
         let substs = TyBuilder::placeholder_subst(db, self.id);
-        let callable_sig = db.callable_item_signature(self.id.into()).substitute(Interner, &substs);
+        let interner = DbInterner::new_with(db, None, None);
+        let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+        let callable_sig = db
+            .callable_item_signature(self.id.into())
+            .instantiate(interner, args)
+            .skip_binder()
+            .to_chalk(interner);
         let skip = if db.function_signature(self.id).has_self_param() { 1 } else { 0 };
         callable_sig
             .params()
@@ -2437,7 +2471,13 @@ impl Function {
                 GenericArg::new(Interner, GenericArgData::Ty(ty))
             })
             .build();
-        let callable_sig = db.callable_item_signature(self.id.into()).substitute(Interner, &substs);
+        let interner = DbInterner::new_with(db, None, None);
+        let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+        let callable_sig = db
+            .callable_item_signature(self.id.into())
+            .instantiate(interner, args)
+            .skip_binder()
+            .to_chalk(interner);
         let skip = if db.function_signature(self.id).has_self_param() { 1 } else { 0 };
         callable_sig
             .params()
@@ -2732,8 +2772,13 @@ impl SelfParam {
 
     pub fn ty<'db>(&self, db: &'db dyn HirDatabase) -> Type<'db> {
         let substs = TyBuilder::placeholder_subst(db, self.func);
-        let callable_sig =
-            db.callable_item_signature(self.func.into()).substitute(Interner, &substs);
+        let interner = DbInterner::new_with(db, None, None);
+        let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+        let callable_sig = db
+            .callable_item_signature(self.func.into())
+            .instantiate(interner, args)
+            .skip_binder()
+            .to_chalk(interner);
         let environment = db.trait_environment(self.func.into());
         let ty = callable_sig.params()[0].clone();
         Type { env: environment, ty, _pd: PhantomCovariantLifetime::new() }
@@ -2765,8 +2810,13 @@ impl SelfParam {
         let parent_substs = TyBuilder::subst_for_def(db, parent_id, None).fill(&mut filler).build();
         let substs =
             TyBuilder::subst_for_def(db, self.func, Some(parent_substs)).fill(&mut filler).build();
-        let callable_sig =
-            db.callable_item_signature(self.func.into()).substitute(Interner, &substs);
+        let interner = DbInterner::new_with(db, None, None);
+        let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+        let callable_sig = db
+            .callable_item_signature(self.func.into())
+            .instantiate(interner, args)
+            .skip_binder()
+            .to_chalk(interner);
         let environment = db.trait_environment(self.func.into());
         let ty = callable_sig.params()[0].clone();
         Type { env: environment, ty, _pd: PhantomCovariantLifetime::new() }
@@ -3770,7 +3820,7 @@ impl GenericDef {
         push_ty_diagnostics(
             db,
             acc,
-            db.generic_predicates_without_parent_with_diagnostics_ns(def).1,
+            db.generic_predicates_without_parent_with_diagnostics(def).1,
             &source_map,
         );
         for (param_id, param) in generics.iter_type_or_consts() {
@@ -3810,12 +3860,12 @@ impl GenericDef {
 pub struct GenericSubstitution<'db> {
     def: GenericDefId,
     subst: Substitution,
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'db>>,
     _pd: PhantomCovariantLifetime<'db>,
 }
 
 impl<'db> GenericSubstitution<'db> {
-    fn new(def: GenericDefId, subst: Substitution, env: Arc<TraitEnvironment>) -> Self {
+    fn new(def: GenericDefId, subst: Substitution, env: Arc<TraitEnvironment<'db>>) -> Self {
         Self { def, subst, env, _pd: PhantomCovariantLifetime::new() }
     }
 
@@ -4495,21 +4545,23 @@ impl Impl {
     }
 
     pub fn trait_(self, db: &dyn HirDatabase) -> Option<Trait> {
-        let trait_ref = db.impl_trait_ns(self.id)?;
+        let trait_ref = db.impl_trait(self.id)?;
         let id = trait_ref.skip_binder().def_id;
         Some(Trait { id: id.0 })
     }
 
     pub fn trait_ref(self, db: &dyn HirDatabase) -> Option<TraitRef<'_>> {
-        let trait_ref = db.impl_trait_ns(self.id)?.instantiate_identity();
+        let trait_ref = db.impl_trait(self.id)?.instantiate_identity();
         let resolver = self.id.resolver(db);
         Some(TraitRef::new_with_resolver(db, &resolver, trait_ref))
     }
 
     pub fn self_ty(self, db: &dyn HirDatabase) -> Type<'_> {
         let resolver = self.id.resolver(db);
+        let interner = DbInterner::new_with(db, Some(resolver.krate()), None);
         let substs = TyBuilder::placeholder_subst(db, self.id);
-        let ty = db.impl_self_ty(self.id).substitute(Interner, &substs);
+        let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+        let ty = db.impl_self_ty(self.id).instantiate(interner, args).to_chalk(interner);
         Type::new_with_resolver_inner(db, &resolver, ty)
     }
 
@@ -4569,7 +4621,7 @@ impl Impl {
 
 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub struct TraitRef<'db> {
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'db>>,
     trait_ref: hir_ty::next_solver::TraitRef<'db>,
     _pd: PhantomCovariantLifetime<'db>,
 }
@@ -4792,7 +4844,7 @@ impl CaptureUsageSource {
 
 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub struct Type<'db> {
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'db>>,
     ty: Ty,
     _pd: PhantomCovariantLifetime<'db>,
 }
@@ -4830,32 +4882,40 @@ impl<'db> Type<'db> {
     }
 
     fn from_def(db: &'db dyn HirDatabase, def: impl Into<TyDefId> + HasResolver) -> Self {
+        let interner = DbInterner::new_with(db, None, None);
         let ty = db.ty(def.into());
         let substs = TyBuilder::unknown_subst(
             db,
             match def.into() {
                 TyDefId::AdtId(it) => GenericDefId::AdtId(it),
                 TyDefId::TypeAliasId(it) => GenericDefId::TypeAliasId(it),
-                TyDefId::BuiltinType(_) => return Type::new(db, def, ty.skip_binders().clone()),
+                TyDefId::BuiltinType(_) => {
+                    return Type::new(db, def, ty.skip_binder().to_chalk(interner));
+                }
             },
         );
-        Type::new(db, def, ty.substitute(Interner, &substs))
+        let args: hir_ty::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+        Type::new(db, def, ty.instantiate(interner, args).to_chalk(interner))
     }
 
     fn from_def_placeholders(
         db: &'db dyn HirDatabase,
         def: impl Into<TyDefId> + HasResolver,
     ) -> Self {
+        let interner = DbInterner::new_with(db, None, None);
         let ty = db.ty(def.into());
         let substs = TyBuilder::placeholder_subst(
             db,
             match def.into() {
                 TyDefId::AdtId(it) => GenericDefId::AdtId(it),
                 TyDefId::TypeAliasId(it) => GenericDefId::TypeAliasId(it),
-                TyDefId::BuiltinType(_) => return Type::new(db, def, ty.skip_binders().clone()),
+                TyDefId::BuiltinType(_) => {
+                    return Type::new(db, def, ty.skip_binder().to_chalk(interner));
+                }
             },
         );
-        Type::new(db, def, ty.substitute(Interner, &substs))
+        let args: hir_ty::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+        Type::new(db, def, ty.instantiate(interner, args).to_chalk(interner))
     }
 
     fn from_value_def(
@@ -4865,6 +4925,7 @@ impl<'db> Type<'db> {
         let Some(ty) = db.value_ty(def.into()) else {
             return Type::new(db, def, TyKind::Error.intern(Interner));
         };
+        let interner = DbInterner::new_with(db, None, None);
         let substs = TyBuilder::unknown_subst(
             db,
             match def.into() {
@@ -4875,10 +4936,13 @@ impl<'db> Type<'db> {
                 ValueTyDefId::EnumVariantId(it) => {
                     GenericDefId::AdtId(AdtId::EnumId(it.lookup(db).parent))
                 }
-                ValueTyDefId::StaticId(_) => return Type::new(db, def, ty.skip_binders().clone()),
+                ValueTyDefId::StaticId(_) => {
+                    return Type::new(db, def, ty.skip_binder().to_chalk(interner));
+                }
             },
         );
-        Type::new(db, def, ty.substitute(Interner, &substs))
+        let args: crate::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+        Type::new(db, def, ty.instantiate(interner, args).to_chalk(interner))
     }
 
     pub fn new_slice(ty: Self) -> Self {
@@ -5173,7 +5237,14 @@ impl<'db> Type<'db> {
             .build();
 
         let goal = Canonical {
-            value: hir_ty::InEnvironment::new(&self.env.env, trait_ref.cast(Interner)),
+            value: hir_ty::InEnvironment::new(
+                &self.env.env.to_chalk(DbInterner::new_with(
+                    db,
+                    Some(self.env.krate),
+                    self.env.block,
+                )),
+                trait_ref.cast(Interner),
+            ),
             binders: CanonicalVarKinds::empty(Interner),
         };
 
@@ -5947,7 +6018,7 @@ impl<'db> Type<'db> {
 
 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub struct TypeNs<'db> {
-    env: Arc<TraitEnvironment>,
+    env: Arc<TraitEnvironment<'db>>,
     ty: hir_ty::next_solver::Ty<'db>,
     _pd: PhantomCovariantLifetime<'db>,
 }
@@ -5965,6 +6036,11 @@ impl<'db> TypeNs<'db> {
         TypeNs { env: environment, ty, _pd: PhantomCovariantLifetime::new() }
     }
 
+    pub fn to_type(&self, db: &'db dyn HirDatabase) -> Type<'db> {
+        let interner = DbInterner::new_with(db, Some(self.env.krate), self.env.block);
+        Type { env: self.env.clone(), ty: convert_ty_for_result(interner, self.ty), _pd: self._pd }
+    }
+
     // FIXME: Find better API that also handles const generics
     pub fn impls_trait(&self, infcx: InferCtxt<'db>, trait_: Trait, args: &[TypeNs<'db>]) -> bool {
         let args = GenericArgs::new_from_iter(
@@ -5988,6 +6064,10 @@ impl<'db> TypeNs<'db> {
         let res = hir_ty::traits::next_trait_solve_in_ctxt(&infcx, goal);
         res.map_or(false, |res| matches!(res.1, rustc_type_ir::solve::Certainty::Yes))
     }
+
+    pub fn is_bool(&self) -> bool {
+        matches!(self.ty.kind(), rustc_type_ir::TyKind::Bool)
+    }
 }
 
 #[derive(Debug, PartialEq, Eq, Copy, Clone, Hash)]
diff --git a/src/tools/rust-analyzer/crates/hir/src/source_analyzer.rs b/src/tools/rust-analyzer/crates/hir/src/source_analyzer.rs
index 539b25387ae..c6b7e84dc20 100644
--- a/src/tools/rust-analyzer/crates/hir/src/source_analyzer.rs
+++ b/src/tools/rust-analyzer/crates/hir/src/source_analyzer.rs
@@ -46,6 +46,10 @@ use hir_ty::{
     from_assoc_type_id,
     lang_items::lang_items_for_bin_op,
     method_resolution,
+    next_solver::{
+        DbInterner,
+        mapping::{ChalkToNextSolver, NextSolverToChalk},
+    },
 };
 use intern::sym;
 use itertools::Itertools;
@@ -219,7 +223,7 @@ impl<'db> SourceAnalyzer<'db> {
         })
     }
 
-    fn trait_environment(&self, db: &'db dyn HirDatabase) -> Arc<TraitEnvironment> {
+    fn trait_environment(&self, db: &'db dyn HirDatabase) -> Arc<TraitEnvironment<'db>> {
         self.body_().map(|(def, ..)| def).map_or_else(
             || TraitEnvironment::empty(self.resolver.krate()),
             |def| db.trait_environment_for_body(def),
@@ -372,8 +376,10 @@ impl<'db> SourceAnalyzer<'db> {
     ) -> Option<Callable<'db>> {
         let expr_id = self.expr_id(call.clone().into())?.as_expr()?;
         let (func, substs) = self.infer()?.method_resolution(expr_id)?;
-        let ty = db.value_ty(func.into())?.substitute(Interner, &substs);
-        let ty = Type::new_with_resolver(db, &self.resolver, ty);
+        let interner = DbInterner::new_with(db, None, None);
+        let args: hir_ty::next_solver::GenericArgs<'_> = substs.to_nextsolver(interner);
+        let ty = db.value_ty(func.into())?.instantiate(interner, args);
+        let ty = Type::new_with_resolver(db, &self.resolver, ty.to_chalk(interner));
         let mut res = ty.as_callable(db)?;
         res.is_bound_method = true;
         Some(res)
diff --git a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/add_braces.rs b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/add_braces.rs
index 745ae67f309..5af622eaf28 100644
--- a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/add_braces.rs
+++ b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/add_braces.rs
@@ -1,3 +1,4 @@
+use either::Either;
 use syntax::{
     AstNode,
     ast::{self, edit_in_place::Indent, syntax_factory::SyntaxFactory},
@@ -59,7 +60,8 @@ enum ParentType {
 }
 
 fn get_replacement_node(ctx: &AssistContext<'_>) -> Option<(ParentType, ast::Expr)> {
-    if let Some(match_arm) = ctx.find_node_at_offset::<ast::MatchArm>() {
+    let node = ctx.find_node_at_offset::<Either<ast::MatchArm, ast::ClosureExpr>>()?;
+    if let Either::Left(match_arm) = &node {
         let match_arm_expr = match_arm.expr()?;
 
         if matches!(match_arm_expr, ast::Expr::BlockExpr(_)) {
@@ -67,7 +69,7 @@ fn get_replacement_node(ctx: &AssistContext<'_>) -> Option<(ParentType, ast::Exp
         }
 
         return Some((ParentType::MatchArmExpr, match_arm_expr));
-    } else if let Some(closure_expr) = ctx.find_node_at_offset::<ast::ClosureExpr>() {
+    } else if let Either::Right(closure_expr) = &node {
         let body = closure_expr.body()?;
 
         if matches!(body, ast::Expr::BlockExpr(_)) {
@@ -106,6 +108,33 @@ fn foo() {
     }
 
     #[test]
+    fn suggest_add_braces_for_closure_in_match() {
+        check_assist(
+            add_braces,
+            r#"
+fn foo() {
+    match () {
+        () => {
+            t(|n|$0 n + 100);
+        }
+    }
+}
+"#,
+            r#"
+fn foo() {
+    match () {
+        () => {
+            t(|n| {
+                n + 100
+            });
+        }
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
     fn no_assist_for_closures_with_braces() {
         check_assist_not_applicable(
             add_braces,
diff --git a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/add_missing_match_arms.rs b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/add_missing_match_arms.rs
index 4d3212c515f..3910921fbe0 100644
--- a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/add_missing_match_arms.rs
+++ b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/add_missing_match_arms.rs
@@ -521,7 +521,7 @@ fn build_pat(
                 hir::StructKind::Tuple => {
                     let mut name_generator = suggest_name::NameGenerator::default();
                     let pats = fields.into_iter().map(|f| {
-                        let name = name_generator.for_type(&f.ty(db), db, edition);
+                        let name = name_generator.for_type(&f.ty(db).to_type(db), db, edition);
                         match name {
                             Some(name) => make::ext::simple_ident_pat(make.name(&name)).into(),
                             None => make.wildcard_pat().into(),
diff --git a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/apply_demorgan.rs b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/apply_demorgan.rs
index 753a9e56c35..53a0a11998a 100644
--- a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/apply_demorgan.rs
+++ b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/apply_demorgan.rs
@@ -6,7 +6,7 @@ use ide_db::{
     syntax_helpers::node_ext::{for_each_tail_expr, walk_expr},
 };
 use syntax::{
-    SyntaxKind, T,
+    NodeOrToken, SyntaxKind, T,
     ast::{
         self, AstNode,
         Expr::BinExpr,
@@ -38,15 +38,27 @@ use crate::{AssistContext, AssistId, Assists, utils::invert_boolean_expression};
 // }
 // ```
 pub(crate) fn apply_demorgan(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> {
-    let mut bin_expr = ctx.find_node_at_offset::<ast::BinExpr>()?;
+    let mut bin_expr = if let Some(not) = ctx.find_token_syntax_at_offset(T![!])
+        && let Some(NodeOrToken::Node(next)) = not.next_sibling_or_token()
+        && let Some(paren) = ast::ParenExpr::cast(next)
+        && let Some(ast::Expr::BinExpr(bin_expr)) = paren.expr()
+    {
+        bin_expr
+    } else {
+        let bin_expr = ctx.find_node_at_offset::<ast::BinExpr>()?;
+        let op_range = bin_expr.op_token()?.text_range();
+
+        // Is the cursor on the expression's logical operator?
+        if !op_range.contains_range(ctx.selection_trimmed()) {
+            return None;
+        }
+
+        bin_expr
+    };
+
     let op = bin_expr.op_kind()?;
     let op_range = bin_expr.op_token()?.text_range();
 
-    // Is the cursor on the expression's logical operator?
-    if !op_range.contains_range(ctx.selection_trimmed()) {
-        return None;
-    }
-
     // Walk up the tree while we have the same binary operator
     while let Some(parent_expr) = bin_expr.syntax().parent().and_then(ast::BinExpr::cast) {
         match parent_expr.op_kind() {
@@ -367,6 +379,15 @@ fn f() { !(S <= S || S < S) }
     }
 
     #[test]
+    fn demorgan_on_not() {
+        check_assist(
+            apply_demorgan,
+            "fn f() { $0!(1 || 3 && 4 || 5) }",
+            "fn f() { !1 && !(3 && 4) && !5 }",
+        )
+    }
+
+    #[test]
     fn demorgan_keep_pars_for_op_precedence() {
         check_assist(
             apply_demorgan,
diff --git a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/bind_unused_param.rs b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/bind_unused_param.rs
index 00c7d25b257..1b24f7fe7ff 100644
--- a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/bind_unused_param.rs
+++ b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/bind_unused_param.rs
@@ -2,7 +2,7 @@ use crate::assist_context::{AssistContext, Assists};
 use ide_db::{LineIndexDatabase, assists::AssistId, defs::Definition};
 use syntax::{
     AstNode,
-    ast::{self, edit_in_place::Indent},
+    ast::{self, HasName, edit_in_place::Indent},
 };
 
 // Assist: bind_unused_param
@@ -22,6 +22,7 @@ pub(crate) fn bind_unused_param(acc: &mut Assists, ctx: &AssistContext<'_>) -> O
     let param: ast::Param = ctx.find_node_at_offset()?;
 
     let Some(ast::Pat::IdentPat(ident_pat)) = param.pat() else { return None };
+    let name = ident_pat.name().filter(|n| !n.text().starts_with('_'))?;
 
     let param_def = {
         let local = ctx.sema.to_def(&ident_pat)?;
@@ -39,14 +40,14 @@ pub(crate) fn bind_unused_param(acc: &mut Assists, ctx: &AssistContext<'_>) -> O
 
     acc.add(
         AssistId::quick_fix("bind_unused_param"),
-        format!("Bind as `let _ = {ident_pat};`"),
+        format!("Bind as `let _ = {name};`"),
         param.syntax().text_range(),
         |builder| {
             let line_index = ctx.db().line_index(ctx.vfs_file_id());
 
             let indent = func.indent_level();
             let text_indent = indent + 1;
-            let mut text = format!("\n{text_indent}let _ = {ident_pat};");
+            let mut text = format!("\n{text_indent}let _ = {name};");
 
             let left_line = line_index.line_col(l_curly_range.end()).line;
             let right_line = line_index.line_col(r_curly_range.start()).line;
@@ -84,6 +85,22 @@ fn foo(y: i32) {
     }
 
     #[test]
+    fn bind_unused_ref_ident_pat() {
+        cov_mark::check!(single_line);
+        check_assist(
+            bind_unused_param,
+            r#"
+fn foo(ref $0y: i32) {}
+"#,
+            r#"
+fn foo(ref y: i32) {
+    let _ = y;
+}
+"#,
+        );
+    }
+
+    #[test]
     fn bind_unused_empty_block_with_newline() {
         check_assist(
             bind_unused_param,
@@ -152,4 +169,14 @@ fn foo(x: i32, $0y: i32) { y; }
 "#,
         );
     }
+
+    #[test]
+    fn keep_underscore_used() {
+        check_assist_not_applicable(
+            bind_unused_param,
+            r#"
+fn foo($0_x: i32, y: i32) {}
+"#,
+        );
+    }
 }
diff --git a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/convert_to_guarded_return.rs b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/convert_to_guarded_return.rs
index 2ea032fb62b..82213ae3217 100644
--- a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/convert_to_guarded_return.rs
+++ b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/convert_to_guarded_return.rs
@@ -1,13 +1,12 @@
 use std::iter::once;
 
-use ide_db::{
-    syntax_helpers::node_ext::{is_pattern_cond, single_let},
-    ty_filter::TryEnum,
-};
+use either::Either;
+use hir::{Semantics, TypeInfo};
+use ide_db::{RootDatabase, ty_filter::TryEnum};
 use syntax::{
     AstNode,
-    SyntaxKind::{FN, FOR_EXPR, LOOP_EXPR, WHILE_EXPR, WHITESPACE},
-    T,
+    SyntaxKind::{CLOSURE_EXPR, FN, FOR_EXPR, LOOP_EXPR, WHILE_EXPR, WHITESPACE},
+    SyntaxNode, T,
     ast::{
         self,
         edit::{AstNodeEdit, IndentLevel},
@@ -44,12 +43,9 @@ use crate::{
 // }
 // ```
 pub(crate) fn convert_to_guarded_return(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> {
-    if let Some(let_stmt) = ctx.find_node_at_offset() {
-        let_stmt_to_guarded_return(let_stmt, acc, ctx)
-    } else if let Some(if_expr) = ctx.find_node_at_offset() {
-        if_expr_to_guarded_return(if_expr, acc, ctx)
-    } else {
-        None
+    match ctx.find_node_at_offset::<Either<ast::LetStmt, ast::IfExpr>>()? {
+        Either::Left(let_stmt) => let_stmt_to_guarded_return(let_stmt, acc, ctx),
+        Either::Right(if_expr) => if_expr_to_guarded_return(if_expr, acc, ctx),
     }
 }
 
@@ -73,13 +69,7 @@ fn if_expr_to_guarded_return(
         return None;
     }
 
-    // Check if there is an IfLet that we can handle.
-    let (if_let_pat, cond_expr) = if is_pattern_cond(cond.clone()) {
-        let let_ = single_let(cond)?;
-        (Some(let_.pat()?), let_.expr()?)
-    } else {
-        (None, cond)
-    };
+    let let_chains = flat_let_chain(cond);
 
     let then_block = if_expr.then_branch()?;
     let then_block = then_block.stmt_list()?;
@@ -106,11 +96,7 @@ fn if_expr_to_guarded_return(
 
     let parent_container = parent_block.syntax().parent()?;
 
-    let early_expression: ast::Expr = match parent_container.kind() {
-        WHILE_EXPR | LOOP_EXPR | FOR_EXPR => make::expr_continue(None),
-        FN => make::expr_return(None),
-        _ => return None,
-    };
+    let early_expression: ast::Expr = early_expression(parent_container, &ctx.sema)?;
 
     then_block.syntax().first_child_or_token().map(|t| t.kind() == T!['{'])?;
 
@@ -132,32 +118,42 @@ fn if_expr_to_guarded_return(
         target,
         |edit| {
             let if_indent_level = IndentLevel::from_node(if_expr.syntax());
-            let replacement = match if_let_pat {
-                None => {
-                    // If.
-                    let new_expr = {
-                        let then_branch =
-                            make::block_expr(once(make::expr_stmt(early_expression).into()), None);
-                        let cond = invert_boolean_expression_legacy(cond_expr);
-                        make::expr_if(cond, then_branch, None).indent(if_indent_level)
-                    };
-                    new_expr.syntax().clone()
-                }
-                Some(pat) => {
+            let replacement = let_chains.into_iter().map(|expr| {
+                if let ast::Expr::LetExpr(let_expr) = &expr
+                    && let (Some(pat), Some(expr)) = (let_expr.pat(), let_expr.expr())
+                {
                     // If-let.
                     let let_else_stmt = make::let_else_stmt(
                         pat,
                         None,
-                        cond_expr,
-                        ast::make::tail_only_block_expr(early_expression),
+                        expr,
+                        ast::make::tail_only_block_expr(early_expression.clone()),
                     );
                     let let_else_stmt = let_else_stmt.indent(if_indent_level);
                     let_else_stmt.syntax().clone()
+                } else {
+                    // If.
+                    let new_expr = {
+                        let then_branch = make::block_expr(
+                            once(make::expr_stmt(early_expression.clone()).into()),
+                            None,
+                        );
+                        let cond = invert_boolean_expression_legacy(expr);
+                        make::expr_if(cond, then_branch, None).indent(if_indent_level)
+                    };
+                    new_expr.syntax().clone()
                 }
-            };
+            });
 
+            let newline = &format!("\n{if_indent_level}");
             let then_statements = replacement
-                .children_with_tokens()
+                .enumerate()
+                .flat_map(|(i, node)| {
+                    (i != 0)
+                        .then(|| make::tokens::whitespace(newline).into())
+                        .into_iter()
+                        .chain(node.children_with_tokens())
+                })
                 .chain(
                     then_block_items
                         .syntax()
@@ -201,11 +197,7 @@ fn let_stmt_to_guarded_return(
             let_stmt.syntax().parent()?.ancestors().find_map(ast::BlockExpr::cast)?;
         let parent_container = parent_block.syntax().parent()?;
 
-        match parent_container.kind() {
-            WHILE_EXPR | LOOP_EXPR | FOR_EXPR => make::expr_continue(None),
-            FN => make::expr_return(None),
-            _ => return None,
-        }
+        early_expression(parent_container, &ctx.sema)?
     };
 
     acc.add(
@@ -232,6 +224,54 @@ fn let_stmt_to_guarded_return(
     )
 }
 
+fn early_expression(
+    parent_container: SyntaxNode,
+    sema: &Semantics<'_, RootDatabase>,
+) -> Option<ast::Expr> {
+    let return_none_expr = || {
+        let none_expr = make::expr_path(make::ext::ident_path("None"));
+        make::expr_return(Some(none_expr))
+    };
+    if let Some(fn_) = ast::Fn::cast(parent_container.clone())
+        && let Some(fn_def) = sema.to_def(&fn_)
+        && let Some(TryEnum::Option) = TryEnum::from_ty(sema, &fn_def.ret_type(sema.db))
+    {
+        return Some(return_none_expr());
+    }
+    if let Some(body) = ast::ClosureExpr::cast(parent_container.clone()).and_then(|it| it.body())
+        && let Some(ret_ty) = sema.type_of_expr(&body).map(TypeInfo::original)
+        && let Some(TryEnum::Option) = TryEnum::from_ty(sema, &ret_ty)
+    {
+        return Some(return_none_expr());
+    }
+
+    Some(match parent_container.kind() {
+        WHILE_EXPR | LOOP_EXPR | FOR_EXPR => make::expr_continue(None),
+        FN | CLOSURE_EXPR => make::expr_return(None),
+        _ => return None,
+    })
+}
+
+fn flat_let_chain(mut expr: ast::Expr) -> Vec<ast::Expr> {
+    let mut chains = vec![];
+
+    while let ast::Expr::BinExpr(bin_expr) = &expr
+        && bin_expr.op_kind() == Some(ast::BinaryOp::LogicOp(ast::LogicOp::And))
+        && let (Some(lhs), Some(rhs)) = (bin_expr.lhs(), bin_expr.rhs())
+    {
+        if let Some(last) = chains.pop_if(|last| !matches!(last, ast::Expr::LetExpr(_))) {
+            chains.push(make::expr_bin_op(rhs, ast::BinaryOp::LogicOp(ast::LogicOp::And), last));
+        } else {
+            chains.push(rhs);
+        }
+        expr = lhs;
+    }
+
+    chains.push(expr);
+    chains.reverse();
+    chains
+}
+
 #[cfg(test)]
 mod tests {
     use crate::tests::{check_assist, check_assist_not_applicable};
@@ -269,6 +309,71 @@ fn main() {
     }
 
     #[test]
+    fn convert_inside_fn_return_option() {
+        check_assist(
+            convert_to_guarded_return,
+            r#"
+//- minicore: option
+fn ret_option() -> Option<()> {
+    bar();
+    if$0 true {
+        foo();
+
+        // comment
+        bar();
+    }
+}
+"#,
+            r#"
+fn ret_option() -> Option<()> {
+    bar();
+    if false {
+        return None;
+    }
+    foo();
+
+    // comment
+    bar();
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn convert_inside_closure() {
+        check_assist(
+            convert_to_guarded_return,
+            r#"
+fn main() {
+    let _f = || {
+        bar();
+        if$0 true {
+            foo();
+
+            // comment
+            bar();
+        }
+    }
+}
+"#,
+            r#"
+fn main() {
+    let _f = || {
+        bar();
+        if false {
+            return;
+        }
+        foo();
+
+        // comment
+        bar();
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
     fn convert_let_inside_fn() {
         check_assist(
             convert_to_guarded_return,
@@ -317,6 +422,82 @@ fn main() {
     }
 
     #[test]
+    fn convert_if_let_result_inside_let() {
+        check_assist(
+            convert_to_guarded_return,
+            r#"
+fn main() {
+    let _x = loop {
+        if$0 let Ok(x) = Err(92) {
+            foo(x);
+        }
+    };
+}
+"#,
+            r#"
+fn main() {
+    let _x = loop {
+        let Ok(x) = Err(92) else { continue };
+        foo(x);
+    };
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn convert_if_let_chain_result() {
+        check_assist(
+            convert_to_guarded_return,
+            r#"
+fn main() {
+    if$0 let Ok(x) = Err(92)
+        && x < 30
+        && let Some(y) = Some(8)
+    {
+        foo(x, y);
+    }
+}
+"#,
+            r#"
+fn main() {
+    let Ok(x) = Err(92) else { return };
+    if x >= 30 {
+        return;
+    }
+    let Some(y) = Some(8) else { return };
+    foo(x, y);
+}
+"#,
+        );
+
+        check_assist(
+            convert_to_guarded_return,
+            r#"
+fn main() {
+    if$0 let Ok(x) = Err(92)
+        && x < 30
+        && y < 20
+        && let Some(y) = Some(8)
+    {
+        foo(x, y);
+    }
+}
+"#,
+            r#"
+fn main() {
+    let Ok(x) = Err(92) else { return };
+    if !(x < 30 && y < 20) {
+        return;
+    }
+    let Some(y) = Some(8) else { return };
+    foo(x, y);
+}
+"#,
+        );
+    }
+
+    #[test]
     fn convert_let_ok_inside_fn() {
         check_assist(
             convert_to_guarded_return,
@@ -561,6 +742,32 @@ fn main() {
     }
 
     #[test]
+    fn convert_let_stmt_inside_fn_return_option() {
+        check_assist(
+            convert_to_guarded_return,
+            r#"
+//- minicore: option
+fn foo() -> Option<i32> {
+    None
+}
+
+fn ret_option() -> Option<i32> {
+    let x$0 = foo();
+}
+"#,
+            r#"
+fn foo() -> Option<i32> {
+    None
+}
+
+fn ret_option() -> Option<i32> {
+    let Some(x) = foo() else { return None };
+}
+"#,
+        );
+    }
+
+    #[test]
     fn convert_let_stmt_inside_loop() {
         check_assist(
             convert_to_guarded_return,
diff --git a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/destructure_struct_binding.rs b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/destructure_struct_binding.rs
index 397327cb4ff..27755db93c8 100644
--- a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/destructure_struct_binding.rs
+++ b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/destructure_struct_binding.rs
@@ -7,7 +7,7 @@ use ide_db::{
     search::{FileReference, SearchScope},
 };
 use itertools::Itertools;
-use syntax::ast::syntax_factory::SyntaxFactory;
+use syntax::ast::{HasName, syntax_factory::SyntaxFactory};
 use syntax::syntax_editor::SyntaxEditor;
 use syntax::{AstNode, Edition, SmolStr, SyntaxNode, ToSmolStr, ast};
 
@@ -71,13 +71,14 @@ fn destructure_struct_binding_impl(
 
 struct StructEditData {
     ident_pat: ast::IdentPat,
+    name: ast::Name,
     kind: hir::StructKind,
     struct_def_path: hir::ModPath,
     visible_fields: Vec<hir::Field>,
     usages: Vec<FileReference>,
     names_in_scope: FxHashSet<SmolStr>,
     has_private_members: bool,
-    is_nested: bool,
+    need_record_field_name: bool,
     is_ref: bool,
     edition: Edition,
 }
@@ -114,7 +115,11 @@ fn collect_data(ident_pat: ast::IdentPat, ctx: &AssistContext<'_>) -> Option<Str
     }
 
     let is_ref = ty.is_reference();
-    let is_nested = ident_pat.syntax().parent().and_then(ast::RecordPatField::cast).is_some();
+    let need_record_field_name = ident_pat
+        .syntax()
+        .parent()
+        .and_then(ast::RecordPatField::cast)
+        .is_some_and(|field| field.colon_token().is_none());
 
     let usages = ctx
         .sema
@@ -133,6 +138,7 @@ fn collect_data(ident_pat: ast::IdentPat, ctx: &AssistContext<'_>) -> Option<Str
     let names_in_scope = get_names_in_scope(ctx, &ident_pat, &usages).unwrap_or_default();
 
     Some(StructEditData {
+        name: ident_pat.name()?,
         ident_pat,
         kind,
         struct_def_path,
@@ -140,7 +146,7 @@ fn collect_data(ident_pat: ast::IdentPat, ctx: &AssistContext<'_>) -> Option<Str
         has_private_members,
         visible_fields,
         names_in_scope,
-        is_nested,
+        need_record_field_name,
         is_ref,
         edition: module.krate().edition(ctx.db()),
     })
@@ -177,6 +183,7 @@ fn destructure_pat(
     field_names: &[(SmolStr, SmolStr)],
 ) {
     let ident_pat = &data.ident_pat;
+    let name = &data.name;
 
     let struct_path = mod_path_to_ast(&data.struct_def_path, data.edition);
     let is_ref = ident_pat.ref_token().is_some();
@@ -194,9 +201,9 @@ fn destructure_pat(
         hir::StructKind::Record => {
             let fields = field_names.iter().map(|(old_name, new_name)| {
                 // Use shorthand syntax if possible
-                if old_name == new_name && !is_mut {
+                if old_name == new_name {
                     make.record_pat_field_shorthand(
-                        make.ident_pat(false, false, make.name(old_name)).into(),
+                        make.ident_pat(is_ref, is_mut, make.name(old_name)).into(),
                     )
                 } else {
                     make.record_pat_field(
@@ -215,8 +222,8 @@ fn destructure_pat(
 
     // If the binding is nested inside a record, we need to wrap the new
     // destructured pattern in a non-shorthand record field
-    let destructured_pat = if data.is_nested {
-        make.record_pat_field(make.name_ref(&ident_pat.to_string()), new_pat).syntax().clone()
+    let destructured_pat = if data.need_record_field_name {
+        make.record_pat_field(make.name_ref(&name.to_string()), new_pat).syntax().clone()
     } else {
         new_pat.syntax().clone()
     };
@@ -288,7 +295,7 @@ fn build_usage_edit(
         Some(field_expr) => Some({
             let field_name: SmolStr = field_expr.name_ref()?.to_string().into();
             let new_field_name = field_names.get(&field_name)?;
-            let new_expr = make.expr_path(ast::make::ext::ident_path(new_field_name));
+            let new_expr = ast::make::expr_path(ast::make::ext::ident_path(new_field_name));
 
             // If struct binding is a reference, we might need to deref field usages
             if data.is_ref {
@@ -298,7 +305,7 @@ fn build_usage_edit(
                     ref_data.wrap_expr(new_expr).syntax().clone_for_update(),
                 )
             } else {
-                (field_expr.syntax().clone(), new_expr.syntax().clone())
+                (field_expr.syntax().clone(), new_expr.syntax().clone_for_update())
             }
         }),
         None => Some((
@@ -579,7 +586,7 @@ mod tests {
             struct Foo { bar: i32, baz: i32 }
 
             fn main() {
-                let Foo { bar: mut bar, baz: mut baz } = Foo { bar: 1, baz: 2 };
+                let Foo { mut bar, mut baz } = Foo { bar: 1, baz: 2 };
                 let bar2 = bar;
                 let baz2 = &baz;
             }
@@ -588,6 +595,86 @@ mod tests {
     }
 
     #[test]
+    fn mut_record_field() {
+        check_assist(
+            destructure_struct_binding,
+            r#"
+            struct Foo { x: () }
+            struct Bar { foo: Foo }
+            fn f(Bar { mut $0foo }: Bar) {}
+            "#,
+            r#"
+            struct Foo { x: () }
+            struct Bar { foo: Foo }
+            fn f(Bar { foo: Foo { mut x } }: Bar) {}
+            "#,
+        )
+    }
+
+    #[test]
+    fn ref_record_field() {
+        check_assist(
+            destructure_struct_binding,
+            r#"
+            struct Foo { x: () }
+            struct Bar { foo: Foo }
+            fn f(Bar { ref $0foo }: Bar) {
+                let _ = foo.x;
+            }
+            "#,
+            r#"
+            struct Foo { x: () }
+            struct Bar { foo: Foo }
+            fn f(Bar { foo: Foo { ref x } }: Bar) {
+                let _ = *x;
+            }
+            "#,
+        )
+    }
+
+    #[test]
+    fn ref_mut_record_field() {
+        check_assist(
+            destructure_struct_binding,
+            r#"
+            struct Foo { x: () }
+            struct Bar { foo: Foo }
+            fn f(Bar { ref mut $0foo }: Bar) {
+                let _ = foo.x;
+            }
+            "#,
+            r#"
+            struct Foo { x: () }
+            struct Bar { foo: Foo }
+            fn f(Bar { foo: Foo { ref mut x } }: Bar) {
+                let _ = *x;
+            }
+            "#,
+        )
+    }
+
+    #[test]
+    fn ref_mut_record_renamed_field() {
+        check_assist(
+            destructure_struct_binding,
+            r#"
+            struct Foo { x: () }
+            struct Bar { foo: Foo }
+            fn f(Bar { foo: ref mut $0foo1 }: Bar) {
+                let _ = foo1.x;
+            }
+            "#,
+            r#"
+            struct Foo { x: () }
+            struct Bar { foo: Foo }
+            fn f(Bar { foo: Foo { ref mut x } }: Bar) {
+                let _ = *x;
+            }
+            "#,
+        )
+    }
+
+    #[test]
     fn mut_ref() {
         check_assist(
             destructure_struct_binding,
@@ -611,6 +698,52 @@ mod tests {
     }
 
     #[test]
+    fn ref_not_add_parenthesis_and_deref_record() {
+        check_assist(
+            destructure_struct_binding,
+            r#"
+            struct Foo { bar: i32, baz: i32 }
+
+            fn main() {
+                let $0foo = &Foo { bar: 1, baz: 2 };
+                let _ = &foo.bar;
+            }
+            "#,
+            r#"
+            struct Foo { bar: i32, baz: i32 }
+
+            fn main() {
+                let Foo { bar, baz } = &Foo { bar: 1, baz: 2 };
+                let _ = bar;
+            }
+            "#,
+        )
+    }
+
+    #[test]
+    fn ref_not_add_parenthesis_and_deref_tuple() {
+        check_assist(
+            destructure_struct_binding,
+            r#"
+            struct Foo(i32, i32);
+
+            fn main() {
+                let $0foo = &Foo(1, 2);
+                let _ = &foo.0;
+            }
+            "#,
+            r#"
+            struct Foo(i32, i32);
+
+            fn main() {
+                let Foo(_0, _1) = &Foo(1, 2);
+                let _ = _0;
+            }
+            "#,
+        )
+    }
+
+    #[test]
     fn record_struct_name_collision() {
         check_assist(
             destructure_struct_binding,
diff --git a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/expand_rest_pattern.rs b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/expand_rest_pattern.rs
index c80b78fd970..b746099e727 100644
--- a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/expand_rest_pattern.rs
+++ b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/expand_rest_pattern.rs
@@ -24,7 +24,7 @@ use crate::{AssistContext, AssistId, Assists};
 // struct Bar { y: Y, z: Z }
 //
 // fn foo(bar: Bar) {
-//     let Bar { y, z  } = bar;
+//     let Bar { y, z } = bar;
 // }
 // ```
 fn expand_record_rest_pattern(
@@ -53,18 +53,17 @@ fn expand_record_rest_pattern(
         |builder| {
             let make = SyntaxFactory::with_mappings();
             let mut editor = builder.make_editor(rest_pat.syntax());
-            let new_field_list = make.record_pat_field_list(old_field_list.fields(), None);
-            for (f, _) in missing_fields.iter() {
-                let field = make.record_pat_field_shorthand(
+            let new_fields = old_field_list.fields().chain(missing_fields.iter().map(|(f, _)| {
+                make.record_pat_field_shorthand(
                     make.ident_pat(
                         false,
                         false,
                         make.name(&f.name(ctx.sema.db).display_no_db(edition).to_smolstr()),
                     )
                     .into(),
-                );
-                new_field_list.add_field(field);
-            }
+                )
+            }));
+            let new_field_list = make.record_pat_field_list(new_fields, None);
 
             editor.replace(old_field_list.syntax(), new_field_list.syntax());
 
@@ -114,9 +113,7 @@ fn expand_tuple_struct_rest_pattern(
     };
 
     let rest_pat = rest_pat.into();
-    let mut pats = pat.fields();
-    let prefix_count = pats.by_ref().position(|p| p == rest_pat)?;
-    let suffix_count = pats.count();
+    let (prefix_count, suffix_count) = calculate_counts(&rest_pat, pat.fields())?;
 
     if fields.len().saturating_sub(prefix_count).saturating_sub(suffix_count) == 0 {
         cov_mark::hit!(no_missing_fields_tuple_struct);
@@ -142,16 +139,13 @@ fn expand_tuple_struct_rest_pattern(
                 pat.fields()
                     .take(prefix_count)
                     .chain(fields[prefix_count..fields.len() - suffix_count].iter().map(|f| {
-                        make.ident_pat(
-                            false,
-                            false,
-                            match name_gen.for_type(&f.ty(ctx.sema.db), ctx.sema.db, ctx.edition())
-                            {
-                                Some(name) => make.name(&name),
-                                None => make.name(&format!("_{}", f.index())),
-                            },
+                        gen_unnamed_pat(
+                            ctx,
+                            &make,
+                            &mut name_gen,
+                            &f.ty(ctx.db()).to_type(ctx.sema.db),
+                            f.index(),
                         )
-                        .into()
                     }))
                     .chain(pat.fields().skip(prefix_count + 1)),
             );
@@ -164,6 +158,134 @@ fn expand_tuple_struct_rest_pattern(
     )
 }
 
+// Assist: expand_tuple_rest_pattern
+//
+// Fills fields by replacing rest pattern in tuple patterns.
+//
+// ```
+// fn foo(bar: (char, i32, i32)) {
+//     let (ch, ..$0) = bar;
+// }
+// ```
+// ->
+// ```
+// fn foo(bar: (char, i32, i32)) {
+//     let (ch, _1, _2) = bar;
+// }
+// ```
+fn expand_tuple_rest_pattern(
+    acc: &mut Assists,
+    ctx: &AssistContext<'_>,
+    pat: ast::TuplePat,
+    rest_pat: ast::RestPat,
+) -> Option<()> {
+    let fields = ctx.sema.type_of_pat(&pat.clone().into())?.original.tuple_fields(ctx.db());
+    let len = fields.len();
+
+    let rest_pat = rest_pat.into();
+    let (prefix_count, suffix_count) = calculate_counts(&rest_pat, pat.fields())?;
+
+    if len.saturating_sub(prefix_count).saturating_sub(suffix_count) == 0 {
+        cov_mark::hit!(no_missing_fields_tuple);
+        return None;
+    }
+
+    let old_range = ctx.sema.original_range_opt(pat.syntax())?;
+    if old_range.file_id != ctx.file_id() {
+        return None;
+    }
+
+    acc.add(
+        AssistId::refactor_rewrite("expand_tuple_rest_pattern"),
+        "Fill tuple fields",
+        rest_pat.syntax().text_range(),
+        |builder| {
+            let make = SyntaxFactory::with_mappings();
+            let mut editor = builder.make_editor(rest_pat.syntax());
+
+            let mut name_gen = NameGenerator::new_from_scope_locals(ctx.sema.scope(pat.syntax()));
+            let new_pat = make.tuple_pat(
+                pat.fields()
+                    .take(prefix_count)
+                    .chain(fields[prefix_count..len - suffix_count].iter().enumerate().map(
+                        |(index, ty)| {
+                            gen_unnamed_pat(ctx, &make, &mut name_gen, ty, prefix_count + index)
+                        },
+                    ))
+                    .chain(pat.fields().skip(prefix_count + 1)),
+            );
+
+            editor.replace(pat.syntax(), new_pat.syntax());
+
+            editor.add_mappings(make.finish_with_mappings());
+            builder.add_file_edits(ctx.vfs_file_id(), editor);
+        },
+    )
+}
+
+// Assist: expand_slice_rest_pattern
+//
+// Fills fields by replacing rest pattern in slice patterns.
+//
+// ```
+// fn foo(bar: [i32; 3]) {
+//     let [first, ..$0] = bar;
+// }
+// ```
+// ->
+// ```
+// fn foo(bar: [i32; 3]) {
+//     let [first, _1, _2] = bar;
+// }
+// ```
+fn expand_slice_rest_pattern(
+    acc: &mut Assists,
+    ctx: &AssistContext<'_>,
+    pat: ast::SlicePat,
+    rest_pat: ast::RestPat,
+) -> Option<()> {
+    let (ty, len) = ctx.sema.type_of_pat(&pat.clone().into())?.original.as_array(ctx.db())?;
+
+    let rest_pat = rest_pat.into();
+    let (prefix_count, suffix_count) = calculate_counts(&rest_pat, pat.pats())?;
+
+    if len.saturating_sub(prefix_count).saturating_sub(suffix_count) == 0 {
+        cov_mark::hit!(no_missing_fields_slice);
+        return None;
+    }
+
+    let old_range = ctx.sema.original_range_opt(pat.syntax())?;
+    if old_range.file_id != ctx.file_id() {
+        return None;
+    }
+
+    acc.add(
+        AssistId::refactor_rewrite("expand_slice_rest_pattern"),
+        "Fill slice fields",
+        rest_pat.syntax().text_range(),
+        |builder| {
+            let make = SyntaxFactory::with_mappings();
+            let mut editor = builder.make_editor(rest_pat.syntax());
+
+            let mut name_gen = NameGenerator::new_from_scope_locals(ctx.sema.scope(pat.syntax()));
+            let new_pat = make.slice_pat(
+                pat.pats()
+                    .take(prefix_count)
+                    .chain(
+                        (prefix_count..len - suffix_count)
+                            .map(|index| gen_unnamed_pat(ctx, &make, &mut name_gen, &ty, index)),
+                    )
+                    .chain(pat.pats().skip(prefix_count + 1)),
+            );
+
+            editor.replace(pat.syntax(), new_pat.syntax());
+
+            editor.add_mappings(make.finish_with_mappings());
+            builder.add_file_edits(ctx.vfs_file_id(), editor);
+        },
+    )
+}
+
 pub(crate) fn expand_rest_pattern(acc: &mut Assists, ctx: &AssistContext<'_>) -> Option<()> {
     let rest_pat = ctx.find_node_at_offset::<ast::RestPat>()?;
     let parent = rest_pat.syntax().parent()?;
@@ -171,15 +293,40 @@ pub(crate) fn expand_rest_pattern(acc: &mut Assists, ctx: &AssistContext<'_>) ->
         match parent {
             ast::RecordPatFieldList(it) => expand_record_rest_pattern(acc, ctx, it.syntax().parent().and_then(ast::RecordPat::cast)?, rest_pat),
             ast::TupleStructPat(it) => expand_tuple_struct_rest_pattern(acc, ctx, it, rest_pat),
-            // FIXME
-            // ast::TuplePat(it) => (),
-            // FIXME
-            // ast::SlicePat(it) => (),
+            ast::TuplePat(it) => expand_tuple_rest_pattern(acc, ctx, it, rest_pat),
+            ast::SlicePat(it) => expand_slice_rest_pattern(acc, ctx, it, rest_pat),
             _ => None,
         }
     }
 }
 
+fn gen_unnamed_pat(
+    ctx: &AssistContext<'_>,
+    make: &SyntaxFactory,
+    name_gen: &mut NameGenerator,
+    ty: &hir::Type<'_>,
+    index: usize,
+) -> ast::Pat {
+    make.ident_pat(
+        false,
+        false,
+        match name_gen.for_type(ty, ctx.sema.db, ctx.edition()) {
+            Some(name) => make.name(&name),
+            None => make.name(&format!("_{index}")),
+        },
+    )
+    .into()
+}
+
+fn calculate_counts(
+    rest_pat: &ast::Pat,
+    mut pats: ast::AstChildren<ast::Pat>,
+) -> Option<(usize, usize)> {
+    let prefix_count = pats.by_ref().position(|p| p == *rest_pat)?;
+    let suffix_count = pats.count();
+    Some((prefix_count, suffix_count))
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -211,7 +358,7 @@ enum Foo {
 fn bar(foo: Foo) {
     match foo {
         Foo::A(_) => false,
-        Foo::B{ y, z  } => true,
+        Foo::B{ y, z } => true,
     };
 }
 "#,
@@ -272,7 +419,7 @@ struct Bar {
 }
 
 fn foo(bar: Bar) {
-    let Bar { y, z  } = bar;
+    let Bar { y, z } = bar;
 }
 "#,
         );
@@ -350,6 +497,79 @@ fn foo(bar: Bar) {
     }
 
     #[test]
+    fn fill_tuple_with_fields() {
+        check_assist(
+            expand_rest_pattern,
+            r#"
+fn foo(bar: (char, i32, i32)) {
+    let (ch, ..$0) = bar;
+}
+"#,
+            r#"
+fn foo(bar: (char, i32, i32)) {
+    let (ch, _1, _2) = bar;
+}
+"#,
+        );
+        check_assist(
+            expand_rest_pattern,
+            r#"
+fn foo(bar: (char, i32, i32)) {
+    let (ch, ..$0, end) = bar;
+}
+"#,
+            r#"
+fn foo(bar: (char, i32, i32)) {
+    let (ch, _1, end) = bar;
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn fill_array_with_fields() {
+        check_assist(
+            expand_rest_pattern,
+            r#"
+fn foo(bar: [i32; 4]) {
+    let [first, ..$0] = bar;
+}
+"#,
+            r#"
+fn foo(bar: [i32; 4]) {
+    let [first, _1, _2, _3] = bar;
+}
+"#,
+        );
+        check_assist(
+            expand_rest_pattern,
+            r#"
+fn foo(bar: [i32; 4]) {
+    let [first, second, ..$0] = bar;
+}
+"#,
+            r#"
+fn foo(bar: [i32; 4]) {
+    let [first, second, _2, _3] = bar;
+}
+"#,
+        );
+        check_assist(
+            expand_rest_pattern,
+            r#"
+fn foo(bar: [i32; 4]) {
+    let [first, second, ..$0, end] = bar;
+}
+"#,
+            r#"
+fn foo(bar: [i32; 4]) {
+    let [first, second, _2, end] = bar;
+}
+"#,
+        );
+    }
+
+    #[test]
     fn fill_fields_struct_generated_by_macro() {
         check_assist(
             expand_rest_pattern,
@@ -376,7 +596,7 @@ macro_rules! position {
 position!(usize);
 
 fn macro_call(pos: Pos) {
-    let Pos { x, y  } = pos;
+    let Pos { x, y } = pos;
 }
 "#,
         );
@@ -420,7 +640,7 @@ enum_gen!(usize);
 fn macro_call(foo: Foo) {
     match foo {
         Foo::A(_) => false,
-        Foo::B{ x, y  } => true,
+        Foo::B{ x, y } => true,
     }
 }
 "#,
@@ -484,6 +704,8 @@ fn bar(foo: Foo) {
         // This is still possible even though it's meaningless
         cov_mark::check!(no_missing_fields);
         cov_mark::check!(no_missing_fields_tuple_struct);
+        cov_mark::check!(no_missing_fields_tuple);
+        cov_mark::check!(no_missing_fields_slice);
         check_assist_not_applicable(
             expand_rest_pattern,
             r#"
@@ -523,5 +745,21 @@ fn foo(bar: Bar) {
 }
 "#,
         );
+        check_assist_not_applicable(
+            expand_rest_pattern,
+            r#"
+fn foo(bar: (i32, i32)) {
+    let (y, ..$0, z) = bar;
+}
+"#,
+        );
+        check_assist_not_applicable(
+            expand_rest_pattern,
+            r#"
+fn foo(bar: [i32; 2]) {
+    let [y, ..$0, z] = bar;
+}
+"#,
+        );
     }
 }
diff --git a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/extract_variable.rs b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/extract_variable.rs
index bd88e8b09ce..da596262962 100644
--- a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/extract_variable.rs
+++ b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/extract_variable.rs
@@ -285,7 +285,7 @@ fn peel_parens(mut expr: ast::Expr) -> ast::Expr {
 /// In general that's true for any expression, but in some cases that would produce invalid code.
 fn valid_target_expr(node: SyntaxNode) -> Option<ast::Expr> {
     match node.kind() {
-        SyntaxKind::PATH_EXPR | SyntaxKind::LOOP_EXPR => None,
+        SyntaxKind::PATH_EXPR | SyntaxKind::LOOP_EXPR | SyntaxKind::LET_EXPR => None,
         SyntaxKind::BREAK_EXPR => ast::BreakExpr::cast(node).and_then(|e| e.expr()),
         SyntaxKind::RETURN_EXPR => ast::ReturnExpr::cast(node).and_then(|e| e.expr()),
         SyntaxKind::BLOCK_EXPR => {
@@ -1404,6 +1404,25 @@ fn main() {
     }
 
     #[test]
+    fn extract_var_let_expr() {
+        check_assist_by_label(
+            extract_variable,
+            r#"
+fn main() {
+    if $0let$0 Some(x) = Some(2+2) {}
+}
+"#,
+            r#"
+fn main() {
+    let $0var_name = Some(2+2);
+    if let Some(x) = var_name {}
+}
+"#,
+            "Extract into variable",
+        );
+    }
+
+    #[test]
     fn extract_var_for_cast() {
         check_assist_by_label(
             extract_variable,
@@ -1739,6 +1758,14 @@ fn main() {
     }
 
     #[test]
+    fn extract_var_for_let_expr_not_applicable() {
+        check_assist_not_applicable(
+            extract_variable,
+            "fn main() { if $0let Some(x) = Some(2+2) {} }",
+        );
+    }
+
+    #[test]
     fn extract_var_unit_expr_not_applicable() {
         check_assist_not_applicable(
             extract_variable,
diff --git a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/generate_default_from_enum_variant.rs b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/generate_default_from_enum_variant.rs
index 6198dbc4ed9..056edb00b68 100644
--- a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/generate_default_from_enum_variant.rs
+++ b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/generate_default_from_enum_variant.rs
@@ -39,6 +39,9 @@ pub(crate) fn generate_default_from_enum_variant(
         cov_mark::hit!(test_gen_default_on_non_unit_variant_not_implemented);
         return None;
     }
+    if !variant.syntax().text_range().contains_range(ctx.selection_trimmed()) {
+        return None;
+    }
 
     if existing_default_impl(&ctx.sema, &variant).is_some() {
         cov_mark::hit!(test_gen_default_impl_already_exists);
@@ -115,6 +118,49 @@ impl Default for Variant {
     }
 
     #[test]
+    fn test_generate_default_selected_variant() {
+        check_assist(
+            generate_default_from_enum_variant,
+            r#"
+//- minicore: default
+enum Variant {
+    Undefined,
+    $0Minor$0,
+    Major,
+}
+"#,
+            r#"
+enum Variant {
+    Undefined,
+    Minor,
+    Major,
+}
+
+impl Default for Variant {
+    fn default() -> Self {
+        Self::Minor
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_generate_default_not_applicable_with_multiple_variant_selection() {
+        check_assist_not_applicable(
+            generate_default_from_enum_variant,
+            r#"
+//- minicore: default
+enum Variant {
+    Undefined,
+    $0Minor,
+    M$0ajor,
+}
+"#,
+        );
+    }
+
+    #[test]
     fn test_generate_default_already_implemented() {
         cov_mark::check!(test_gen_default_impl_already_exists);
         check_assist_not_applicable(
diff --git a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/invert_if.rs b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/invert_if.rs
index d198870b023..7576d2fab97 100644
--- a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/invert_if.rs
+++ b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/invert_if.rs
@@ -125,6 +125,18 @@ mod tests {
     }
 
     #[test]
+    fn invert_if_doesnt_apply_with_if_let_chain() {
+        check_assist_not_applicable(
+            invert_if,
+            "fn f() { i$0f x && let Some(_) = Some(1) { 1 } else { 0 } }",
+        );
+        check_assist_not_applicable(
+            invert_if,
+            "fn f() { i$0f let Some(_) = Some(1) && x { 1 } else { 0 } }",
+        );
+    }
+
+    #[test]
     fn invert_if_option_case() {
         check_assist(
             invert_if,
diff --git a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/pull_assignment_up.rs b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/pull_assignment_up.rs
index 21debf6745a..00902fafe82 100644
--- a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/pull_assignment_up.rs
+++ b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/pull_assignment_up.rs
@@ -53,6 +53,10 @@ pub(crate) fn pull_assignment_up(acc: &mut Assists, ctx: &AssistContext<'_>) ->
     };
 
     let tgt: ast::Expr = if let Some(if_expr) = ctx.find_node_at_offset::<ast::IfExpr>() {
+        let if_expr = std::iter::successors(Some(if_expr), |it| {
+            it.syntax().parent().and_then(ast::IfExpr::cast)
+        })
+        .last()?;
         collector.collect_if(&if_expr)?;
         if_expr.into()
     } else if let Some(match_expr) = ctx.find_node_at_offset::<ast::MatchExpr>() {
@@ -238,6 +242,37 @@ fn foo() {
     }
 
     #[test]
+    fn test_pull_assignment_up_inner_if() {
+        check_assist(
+            pull_assignment_up,
+            r#"
+fn foo() {
+    let mut a = 1;
+
+    if true {
+        a = 2;
+    } else if true {
+        $0a = 3;
+    } else {
+        a = 4;
+    }
+}"#,
+            r#"
+fn foo() {
+    let mut a = 1;
+
+    a = if true {
+        2
+    } else if true {
+        3
+    } else {
+        4
+    };
+}"#,
+        );
+    }
+
+    #[test]
     fn test_pull_assignment_up_match() {
         check_assist(
             pull_assignment_up,
diff --git a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/remove_dbg.rs b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/remove_dbg.rs
index 414f6746d44..08779a3ed1f 100644
--- a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/remove_dbg.rs
+++ b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/remove_dbg.rs
@@ -83,7 +83,9 @@ fn compute_dbg_replacement(
     let input_expressions = input_expressions
         .into_iter()
         .filter_map(|(is_sep, group)| (!is_sep).then_some(group))
-        .map(|mut tokens| syntax::hacks::parse_expr_from_str(&tokens.join(""), Edition::CURRENT))
+        .map(|tokens| tokens.collect::<Vec<_>>())
+        .filter(|tokens| !tokens.iter().all(|it| it.kind().is_trivia()))
+        .map(|tokens| syntax::hacks::parse_expr_from_str(&tokens.iter().join(""), Edition::CURRENT))
         .collect::<Option<Vec<ast::Expr>>>()?;
 
     let parent = macro_expr.syntax().parent()?;
@@ -268,6 +270,8 @@ fn foo() {
     dbg!('x');
     dbg!(&n);
     dbg!(n);
+    dbg!(n,);
+    dbg!(n, );
     // needless comment
     dbg!("foo");$0
 }
@@ -282,6 +286,17 @@ fn foo() {
     }
 
     #[test]
+    fn test_remove_trailing_comma_dbg() {
+        check("$0dbg!(1 + 1,)", "1 + 1");
+        check("$0dbg!(1 + 1, )", "1 + 1");
+        check("$0dbg!(1 + 1,\n)", "1 + 1");
+        check("$0dbg!(1 + 1, 2 + 3)", "(1 + 1, 2 + 3)");
+        check("$0dbg!(1 + 1, 2 + 3 )", "(1 + 1, 2 + 3)");
+        check("$0dbg!(1 + 1, 2 + 3, )", "(1 + 1, 2 + 3)");
+        check("$0dbg!(1 + 1, 2 + 3 ,)", "(1 + 1, 2 + 3)");
+    }
+
+    #[test]
     fn test_remove_dbg_not_applicable() {
         check_assist_not_applicable(remove_dbg, "fn main() {$0vec![1, 2, 3]}");
         check_assist_not_applicable(remove_dbg, "fn main() {$0dbg(5, 6, 7)}");
diff --git a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/replace_arith_op.rs b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/replace_arith_op.rs
index 440ab4d4604..a3fb851fb0e 100644
--- a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/replace_arith_op.rs
+++ b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/replace_arith_op.rs
@@ -1,7 +1,7 @@
 use ide_db::assists::{AssistId, GroupLabel};
 use syntax::{
-    AstNode, TextRange,
-    ast::{self, ArithOp, BinaryOp},
+    AstNode,
+    ast::{self, ArithOp, BinaryOp, syntax_factory::SyntaxFactory},
 };
 
 use crate::assist_context::{AssistContext, Assists};
@@ -71,24 +71,31 @@ pub(crate) fn replace_arith_with_wrapping(
 
 fn replace_arith(acc: &mut Assists, ctx: &AssistContext<'_>, kind: ArithKind) -> Option<()> {
     let (lhs, op, rhs) = parse_binary_op(ctx)?;
+    let op_expr = lhs.syntax().parent()?;
 
     if !is_primitive_int(ctx, &lhs) || !is_primitive_int(ctx, &rhs) {
         return None;
     }
 
-    let start = lhs.syntax().text_range().start();
-    let end = rhs.syntax().text_range().end();
-    let range = TextRange::new(start, end);
-
     acc.add_group(
         &GroupLabel("Replace arithmetic...".into()),
         kind.assist_id(),
         kind.label(),
-        range,
+        op_expr.text_range(),
         |builder| {
+            let mut edit = builder.make_editor(rhs.syntax());
+            let make = SyntaxFactory::with_mappings();
             let method_name = kind.method_name(op);
 
-            builder.replace(range, format!("{lhs}.{method_name}({rhs})"))
+            let needs_parentheses =
+                lhs.precedence().needs_parentheses_in(ast::prec::ExprPrecedence::Postfix);
+            let receiver = if needs_parentheses { make.expr_paren(lhs).into() } else { lhs };
+            let arith_expr =
+                make.expr_method_call(receiver, make.name_ref(&method_name), make.arg_list([rhs]));
+            edit.replace(op_expr, arith_expr.syntax());
+
+            edit.add_mappings(make.finish_with_mappings());
+            builder.add_file_edits(ctx.vfs_file_id(), edit);
         },
     )
 }
@@ -228,6 +235,23 @@ fn main() {
     }
 
     #[test]
+    fn replace_arith_with_wrapping_add_add_parenthesis() {
+        check_assist(
+            replace_arith_with_wrapping,
+            r#"
+fn main() {
+    let x = 1*x $0+ 2;
+}
+"#,
+            r#"
+fn main() {
+    let x = (1*x).wrapping_add(2);
+}
+"#,
+        )
+    }
+
+    #[test]
     fn replace_arith_not_applicable_with_non_empty_selection() {
         check_assist_not_applicable(
             replace_arith_with_checked,
diff --git a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/replace_if_let_with_match.rs b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/replace_if_let_with_match.rs
index dd244375dc9..3b815a467bc 100644
--- a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/replace_if_let_with_match.rs
+++ b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/replace_if_let_with_match.rs
@@ -328,7 +328,14 @@ fn pick_pattern_and_expr_order(
         (pat, pat2) => match (binds_name(sema, &pat), binds_name(sema, &pat2)) {
             (true, true) => return None,
             (true, false) => (pat, guard, expr, expr2),
-            (false, true) => (pat2, guard2, expr2, expr),
+            (false, true) => {
+                // This pattern triggers an invalid transformation.
+                // See issues #11373, #19443
+                if let ast::Pat::IdentPat(_) = pat2 {
+                    return None;
+                }
+                (pat2, guard2, expr2, expr)
+            }
             _ if is_sad_pat(sema, &pat) => (pat2, guard2, expr2, expr),
             (false, false) => (pat, guard, expr, expr2),
         },
@@ -1892,4 +1899,19 @@ fn main() {
 "#,
         )
     }
+
+    #[test]
+    fn test_replace_match_with_if_let_not_applicable_pat2_is_ident_pat() {
+        check_assist_not_applicable(
+            replace_match_with_if_let,
+            r"
+fn test(a: i32) {
+    match$0 a {
+        1 => code(),
+        other => code(other),
+    }
+}
+",
+        )
+    }
 }
diff --git a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/replace_is_method_with_if_let_method.rs b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/replace_is_method_with_if_let_method.rs
index 5ef8ba46b9e..f507cae1bb0 100644
--- a/src/tools/rust-analyzer/crates/ide-assists/src/handlers/replace_is_method_with_if_let_method.rs
+++ b/src/tools/rust-analyzer/crates/ide-assists/src/handlers/replace_is_method_with_if_let_method.rs
@@ -31,6 +31,9 @@ pub(crate) fn replace_is_method_with_if_let_method(
         ast::Expr::MethodCallExpr(call) => call,
         _ => return None,
     };
+    if ctx.offset() > if_expr.then_branch()?.stmt_list()?.l_curly_token()?.text_range().end() {
+        return None;
+    }
 
     let name_ref = call_expr.name_ref()?;
     match name_ref.text().as_str() {
@@ -191,4 +194,19 @@ fn main() {
 "#,
         );
     }
+
+    #[test]
+    fn replace_is_some_with_if_let_some_not_applicable_after_l_curly() {
+        check_assist_not_applicable(
+            replace_is_method_with_if_let_method,
+            r#"
+fn main() {
+    let x = Some(1);
+    if x.is_some() {
+        ()$0
+    }
+}
+"#,
+        );
+    }
 }
diff --git a/src/tools/rust-analyzer/crates/ide-assists/src/tests/generated.rs b/src/tools/rust-analyzer/crates/ide-assists/src/tests/generated.rs
index 91348be97eb..e7f91ff3fbc 100644
--- a/src/tools/rust-analyzer/crates/ide-assists/src/tests/generated.rs
+++ b/src/tools/rust-analyzer/crates/ide-assists/src/tests/generated.rs
@@ -1035,7 +1035,41 @@ fn foo(bar: Bar) {
 struct Bar { y: Y, z: Z }
 
 fn foo(bar: Bar) {
-    let Bar { y, z  } = bar;
+    let Bar { y, z } = bar;
+}
+"#####,
+    )
+}
+
+#[test]
+fn doctest_expand_slice_rest_pattern() {
+    check_doc_test(
+        "expand_slice_rest_pattern",
+        r#####"
+fn foo(bar: [i32; 3]) {
+    let [first, ..$0] = bar;
+}
+"#####,
+        r#####"
+fn foo(bar: [i32; 3]) {
+    let [first, _1, _2] = bar;
+}
+"#####,
+    )
+}
+
+#[test]
+fn doctest_expand_tuple_rest_pattern() {
+    check_doc_test(
+        "expand_tuple_rest_pattern",
+        r#####"
+fn foo(bar: (char, i32, i32)) {
+    let (ch, ..$0) = bar;
+}
+"#####,
+        r#####"
+fn foo(bar: (char, i32, i32)) {
+    let (ch, _1, _2) = bar;
 }
 "#####,
     )
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/completions.rs b/src/tools/rust-analyzer/crates/ide-completion/src/completions.rs
index e36e0e57045..eb2bb31f963 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/completions.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/completions.rs
@@ -691,6 +691,9 @@ pub(super) fn complete_name(
         NameKind::RecordField => {
             field::complete_field_list_record_variant(acc, ctx);
         }
+        NameKind::TypeParam => {
+            acc.add_keyword_snippet(ctx, "const", "const $1: $0");
+        }
         NameKind::ConstParam
         | NameKind::Enum
         | NameKind::MacroDef
@@ -700,7 +703,6 @@ pub(super) fn complete_name(
         | NameKind::Static
         | NameKind::Struct
         | NameKind::Trait
-        | NameKind::TypeParam
         | NameKind::Union
         | NameKind::Variant => (),
     }
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/completions/attribute.rs b/src/tools/rust-analyzer/crates/ide-completion/src/completions/attribute.rs
index c542e140df5..e174b0c8922 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/completions/attribute.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/completions/attribute.rs
@@ -70,7 +70,7 @@ pub(crate) fn complete_known_attribute_input(
 
             lint::complete_lint(acc, ctx, colon_prefix, &existing_lints, &lints);
         }
-        ["cfg"] => cfg::complete_cfg(acc, ctx),
+        ["cfg"] | ["cfg_attr"] => cfg::complete_cfg(acc, ctx),
         ["macro_use"] => macro_use::complete_macro_use(
             acc,
             ctx,
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/completions/attribute/cfg.rs b/src/tools/rust-analyzer/crates/ide-completion/src/completions/attribute/cfg.rs
index 1676a8467c8..b2e8efde8be 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/completions/attribute/cfg.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/completions/attribute/cfg.rs
@@ -53,15 +53,33 @@ pub(crate) fn complete_cfg(acc: &mut Completions, ctx: &CompletionContext<'_>) {
                 acc.add(item.build(ctx.db));
             }),
         },
-        None => ctx.krate.potential_cfg(ctx.db).get_cfg_keys().cloned().unique().for_each(|s| {
-            let s = s.as_str();
-            let item =
-                CompletionItem::new(SymbolKind::BuiltinAttr, ctx.source_range(), s, ctx.edition);
-            acc.add(item.build(ctx.db));
-        }),
+        None => ctx
+            .krate
+            .potential_cfg(ctx.db)
+            .get_cfg_keys()
+            .unique()
+            .map(|s| (s.as_str(), ""))
+            .chain(CFG_CONDITION.iter().copied())
+            .for_each(|(s, snippet)| {
+                let mut item = CompletionItem::new(
+                    SymbolKind::BuiltinAttr,
+                    ctx.source_range(),
+                    s,
+                    ctx.edition,
+                );
+                if let Some(cap) = ctx.config.snippet_cap
+                    && !snippet.is_empty()
+                {
+                    item.insert_snippet(cap, snippet);
+                }
+                acc.add(item.build(ctx.db));
+            }),
     }
 }
 
+const CFG_CONDITION: &[(&str, &str)] =
+    &[("all", "all($0)"), ("any", "any($0)"), ("not", "not($0)")];
+
 const KNOWN_ARCH: [&str; 20] = [
     "aarch64",
     "arm",
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/completions/expr.rs b/src/tools/rust-analyzer/crates/ide-completion/src/completions/expr.rs
index a7df0ab3863..080875e0163 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/completions/expr.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/completions/expr.rs
@@ -59,6 +59,7 @@ pub(crate) fn complete_expr_path(
         in_block_expr,
         in_breakable,
         after_if_expr,
+        before_else_kw,
         in_condition,
         incomplete_let,
         after_incomplete_let,
@@ -386,7 +387,7 @@ pub(crate) fn complete_expr_path(
                         add_keyword("let", "let $1 = $0;");
                     }
 
-                    if after_if_expr || after_incomplete_let {
+                    if !before_else_kw && (after_if_expr || after_incomplete_let) {
                         add_keyword("else", "else {\n    $0\n}");
                     }
 
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/completions/record.rs b/src/tools/rust-analyzer/crates/ide-completion/src/completions/record.rs
index 36f38a70db6..2f5abd18934 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/completions/record.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/completions/record.rs
@@ -28,7 +28,11 @@ pub(crate) fn complete_record_pattern_fields(
                     record_pat.record_pat_field_list().and_then(|fl| fl.fields().next()).is_some();
 
                 match were_fields_specified {
-                    false => un.fields(ctx.db).into_iter().map(|f| (f, f.ty(ctx.db))).collect(),
+                    false => un
+                        .fields(ctx.db)
+                        .into_iter()
+                        .map(|f| (f, f.ty(ctx.db).to_type(ctx.db)))
+                        .collect(),
                     true => return,
                 }
             }
@@ -56,7 +60,11 @@ pub(crate) fn complete_record_expr_fields(
                 record_expr.record_expr_field_list().and_then(|fl| fl.fields().next()).is_some();
 
             match were_fields_specified {
-                false => un.fields(ctx.db).into_iter().map(|f| (f, f.ty(ctx.db))).collect(),
+                false => un
+                    .fields(ctx.db)
+                    .into_iter()
+                    .map(|f| (f, f.ty(ctx.db).to_type(ctx.db)))
+                    .collect(),
                 true => return,
             }
         }
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/context.rs b/src/tools/rust-analyzer/crates/ide-completion/src/context.rs
index 007475688d2..9deaaf66312 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/context.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/context.rs
@@ -144,6 +144,7 @@ pub(crate) struct PathExprCtx<'db> {
     pub(crate) in_block_expr: bool,
     pub(crate) in_breakable: BreakableKind,
     pub(crate) after_if_expr: bool,
+    pub(crate) before_else_kw: bool,
     /// Whether this expression is the direct condition of an if or while expression
     pub(crate) in_condition: bool,
     pub(crate) incomplete_let: bool,
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/context/analysis.rs b/src/tools/rust-analyzer/crates/ide-completion/src/context/analysis.rs
index b33a547dee9..77a94403abb 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/context/analysis.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/context/analysis.rs
@@ -1,6 +1,7 @@
 //! Module responsible for analyzing the code surrounding the cursor for completion.
 use std::iter;
 
+use base_db::salsa;
 use hir::{ExpandResult, InFile, Semantics, Type, TypeInfo, Variant};
 use ide_db::{RootDatabase, active_parameter::ActiveParameter};
 use itertools::Either;
@@ -85,9 +86,15 @@ pub(super) fn expand_and_analyze<'db>(
     let original_offset = expansion.original_offset + relative_offset;
     let token = expansion.original_file.token_at_offset(original_offset).left_biased()?;
 
-    analyze(sema, expansion, original_token, &token).map(|(analysis, expected, qualifier_ctx)| {
-        AnalysisResult { analysis, expected, qualifier_ctx, token, original_offset }
-    })
+    salsa::attach(sema.db, || analyze(sema, expansion, original_token, &token)).map(
+        |(analysis, expected, qualifier_ctx)| AnalysisResult {
+            analysis,
+            expected,
+            qualifier_ctx,
+            token,
+            original_offset,
+        },
+    )
 }
 
 fn token_at_offset_ignore_whitespace(file: &SyntaxNode, offset: TextSize) -> Option<SyntaxToken> {
@@ -637,6 +644,9 @@ fn expected_type_and_name<'db>(
                             .or_else(|| it.rhs().and_then(|rhs| sema.type_of_expr(&rhs)))
                             .map(TypeInfo::original);
                         (ty, None)
+                    } else if let Some(ast::BinaryOp::LogicOp(_)) = it.op_kind() {
+                        let ty = sema.type_of_expr(&it.clone().into()).map(TypeInfo::original);
+                        (ty, None)
                     } else {
                         (None, None)
                     }
@@ -707,9 +717,13 @@ fn expected_type_and_name<'db>(
                     (ty, None)
                 },
                 ast::IfExpr(it) => {
-                    let ty = it.condition()
-                        .and_then(|e| sema.type_of_expr(&e))
-                        .map(TypeInfo::original);
+                    let ty = if let Some(body) = it.then_branch()
+                        && token.text_range().end() > body.syntax().text_range().start()
+                    {
+                        sema.type_of_expr(&body.into())
+                    } else {
+                        it.condition().and_then(|e| sema.type_of_expr(&e))
+                    }.map(TypeInfo::original);
                     (ty, None)
                 },
                 ast::IdentPat(it) => {
@@ -1282,11 +1296,12 @@ fn classify_name_ref<'db>(
         let after_incomplete_let = after_incomplete_let(it.clone()).is_some();
         let incomplete_expr_stmt =
             it.parent().and_then(ast::ExprStmt::cast).map(|it| it.semicolon_token().is_none());
+        let before_else_kw = before_else_kw(it);
         let incomplete_let = it
             .parent()
             .and_then(ast::LetStmt::cast)
             .is_some_and(|it| it.semicolon_token().is_none())
-            || after_incomplete_let && incomplete_expr_stmt.unwrap_or(true) && !before_else_kw(it);
+            || after_incomplete_let && incomplete_expr_stmt.unwrap_or(true) && !before_else_kw;
         let in_value = it.parent().and_then(Either::<ast::LetStmt, ast::ArgList>::cast).is_some();
         let impl_ = fetch_immediate_impl(sema, original_file, expr.syntax());
 
@@ -1302,6 +1317,7 @@ fn classify_name_ref<'db>(
                 in_block_expr,
                 in_breakable: in_loop_body,
                 after_if_expr,
+                before_else_kw,
                 in_condition,
                 ref_expr_parent,
                 after_amp,
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/context/tests.rs b/src/tools/rust-analyzer/crates/ide-completion/src/context/tests.rs
index 445afa75f3f..d9ec7915e3c 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/context/tests.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/context/tests.rs
@@ -279,6 +279,62 @@ fn foo() {
 }
 
 #[test]
+fn expected_type_if_let_chain_bool() {
+    check_expected_type_and_name(
+        r#"
+fn foo() {
+    let f = Foo::Quux;
+    if let c = f && $0 { }
+}
+"#,
+        expect![[r#"ty: bool, name: ?"#]],
+    );
+}
+
+#[test]
+fn expected_type_if_condition() {
+    check_expected_type_and_name(
+        r#"
+fn foo() {
+    if a$0 { }
+}
+"#,
+        expect![[r#"ty: bool, name: ?"#]],
+    );
+}
+
+#[test]
+fn expected_type_if_body() {
+    check_expected_type_and_name(
+        r#"
+enum Foo { Bar, Baz, Quux }
+
+fn foo() {
+    let _: Foo = if true {
+        $0
+    };
+}
+"#,
+        expect![[r#"ty: Foo, name: ?"#]],
+    );
+
+    check_expected_type_and_name(
+        r#"
+enum Foo { Bar, Baz, Quux }
+
+fn foo() {
+    let _: Foo = if true {
+        Foo::Bar
+    } else {
+        $0
+    };
+}
+"#,
+        expect![[r#"ty: Foo, name: ?"#]],
+    );
+}
+
+#[test]
 fn expected_type_fn_ret_without_leading_char() {
     cov_mark::check!(expected_type_fn_ret_without_leading_char);
     check_expected_type_and_name(
@@ -526,3 +582,16 @@ fn foo() {
         expect![[r#"ty: State, name: ?"#]],
     );
 }
+
+#[test]
+fn expected_type_logic_op() {
+    check_expected_type_and_name(
+        r#"
+enum State { Stop }
+fn foo() {
+    true && $0;
+}
+"#,
+        expect![[r#"ty: bool, name: ?"#]],
+    );
+}
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/render/pattern.rs b/src/tools/rust-analyzer/crates/ide-completion/src/render/pattern.rs
index 60ec1128233..312d3bd426f 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/render/pattern.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/render/pattern.rs
@@ -163,6 +163,7 @@ fn render_pat(
         PatternContext {
             param_ctx: Some(ParamContext { kind: ParamKind::Function(_), .. }),
             has_type_ascription: false,
+            parent_pat: None,
             ..
         }
     );
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/tests.rs b/src/tools/rust-analyzer/crates/ide-completion/src/tests.rs
index 809a26bf5de..b20b570c2b8 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/tests.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/tests.rs
@@ -26,6 +26,7 @@ mod visibility;
 
 use base_db::{SourceDatabase, salsa};
 use expect_test::Expect;
+use hir::db::HirDatabase;
 use hir::{PrefixKind, setup_tracing};
 use ide_db::{
     FilePosition, RootDatabase, SnippetCap,
@@ -306,8 +307,11 @@ pub(crate) fn get_all_items(
     trigger_character: Option<char>,
 ) -> Vec<CompletionItem> {
     let (db, position) = position(code);
-    let res = salsa::attach(&db, || crate::completions(&db, &config, position, trigger_character))
-        .map_or_else(Vec::default, Into::into);
+    let res = salsa::attach(&db, || {
+        HirDatabase::zalsa_register_downcaster(&db);
+        crate::completions(&db, &config, position, trigger_character)
+    })
+    .map_or_else(Vec::default, Into::into);
     // validate
     res.iter().for_each(|it| {
         let sr = it.source_range;
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/tests/attribute.rs b/src/tools/rust-analyzer/crates/ide-completion/src/tests/attribute.rs
index 46a36300459..1d2a9c7c8d3 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/tests/attribute.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/tests/attribute.rs
@@ -815,7 +815,10 @@ mod cfg {
 #[cfg($0)]
 "#,
             expect![[r#"
+                ba all
+                ba any
                 ba dbg
+                ba not
                 ba opt_level
                 ba test
                 ba true
@@ -827,7 +830,74 @@ mod cfg {
 #[cfg(b$0)]
 "#,
             expect![[r#"
+                ba all
+                ba any
                 ba dbg
+                ba not
+                ba opt_level
+                ba test
+                ba true
+            "#]],
+        );
+    }
+
+    #[test]
+    fn inside_cfg_attr() {
+        check(
+            r#"
+//- /main.rs cfg:test,dbg=false,opt_level=2
+#[cfg_attr($0)]
+"#,
+            expect![[r#"
+                ba all
+                ba any
+                ba dbg
+                ba not
+                ba opt_level
+                ba test
+                ba true
+            "#]],
+        );
+        check(
+            r#"
+//- /main.rs cfg:test,dbg=false,opt_level=2
+#[cfg_attr(b$0)]
+"#,
+            expect![[r#"
+                ba all
+                ba any
+                ba dbg
+                ba not
+                ba opt_level
+                ba test
+                ba true
+            "#]],
+        );
+        check(
+            r#"
+//- /main.rs cfg:test,dbg=false,opt_level=2
+#[cfg_attr($0, allow(deprecated))]
+"#,
+            expect![[r#"
+                ba all
+                ba any
+                ba dbg
+                ba not
+                ba opt_level
+                ba test
+                ba true
+            "#]],
+        );
+        check(
+            r#"
+//- /main.rs cfg:test,dbg=false,opt_level=2
+#[cfg_attr(b$0, allow(deprecated))]
+"#,
+            expect![[r#"
+                ba all
+                ba any
+                ba dbg
+                ba not
                 ba opt_level
                 ba test
                 ba true
@@ -852,6 +922,20 @@ mod cfg {
             "#]],
         );
     }
+
+    #[test]
+    fn inside_conditional() {
+        check_edit(
+            "all",
+            r#"
+//- /main.rs cfg:test,dbg=false,opt_level=2
+#[cfg($0)]
+"#,
+            r#"
+#[cfg(all($0))]
+"#,
+        );
+    }
 }
 
 mod derive {
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/tests/expression.rs b/src/tools/rust-analyzer/crates/ide-completion/src/tests/expression.rs
index 5cc72ef845b..98a6f95f334 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/tests/expression.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/tests/expression.rs
@@ -271,8 +271,6 @@ fn complete_in_block() {
             sn macro_rules
             sn pd
             sn ppd
-            ex false
-            ex true
         "#]],
     )
 }
@@ -1668,12 +1666,138 @@ fn foo() { let x = if foo {} $0; let y = 92; }
 fn foo() { let x = if foo {} $0 else {}; }
 "#,
         expect![[r#"
-            fn foo    fn()
+            fn foo()  fn()
+            bt u32     u32
+            kw async
+            kw const
+            kw crate::
+            kw else if
+            kw enum
+            kw extern
+            kw false
+            kw fn
+            kw for
+            kw if
+            kw if let
+            kw impl
+            kw impl for
+            kw let
+            kw letm
+            kw loop
+            kw match
+            kw mod
+            kw return
+            kw self::
+            kw static
+            kw struct
+            kw trait
+            kw true
+            kw type
+            kw union
+            kw unsafe
+            kw use
+            kw while
+            kw while let
+            sn macro_rules
+            sn pd
+            sn ppd
+        "#]],
+    );
+    check(
+        r#"
+fn foo() { let x = if foo {} $0 else if true {}; }
+"#,
+        expect![[r#"
+            fn foo()  fn()
+            bt u32     u32
+            kw async
+            kw const
+            kw crate::
+            kw else if
+            kw enum
+            kw extern
+            kw false
+            kw fn
+            kw for
+            kw if
+            kw if let
+            kw impl
+            kw impl for
+            kw let
+            kw letm
+            kw loop
+            kw match
+            kw mod
+            kw return
+            kw self::
+            kw static
+            kw struct
+            kw trait
+            kw true
+            kw type
+            kw union
+            kw unsafe
+            kw use
+            kw while
+            kw while let
+            sn macro_rules
+            sn pd
+            sn ppd
+        "#]],
+    );
+    check(
+        r#"
+fn foo() { let x = if foo {} el$0 else if true {} else {}; }
+"#,
+        expect![[r#"
+            fn foo()  fn()
+            lc x        ()
+            bt u32     u32
+            kw async
+            kw const
+            kw crate::
+            kw else if
+            kw enum
+            kw extern
+            kw false
+            kw fn
+            kw for
+            kw if
+            kw if let
+            kw impl
+            kw impl for
+            kw let
+            kw letm
+            kw loop
+            kw match
+            kw mod
+            kw return
+            kw self::
+            kw static
+            kw struct
+            kw trait
+            kw true
+            kw type
+            kw union
+            kw unsafe
+            kw use
+            kw while
+            kw while let
+            sn macro_rules
+            sn pd
+            sn ppd
+        "#]],
+    );
+    check(
+        r#"
+fn foo() { let x = if foo {} $0 else if true {} else {}; }
+"#,
+        expect![[r#"
+            fn foo()  fn()
             bt u32     u32
             kw async
             kw const
             kw crate::
-            kw else
             kw else if
             kw enum
             kw extern
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/tests/pattern.rs b/src/tools/rust-analyzer/crates/ide-completion/src/tests/pattern.rs
index 9ec27252fd7..6eb0b818d69 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/tests/pattern.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/tests/pattern.rs
@@ -399,6 +399,25 @@ fn foo($0) {}
 }
 
 #[test]
+fn completes_in_fn_param_in_nested_pattern() {
+    check(
+        r#"
+struct Foo { num: u32 }
+struct Bar(Foo);
+fn foo(Bar($0)) {}
+"#,
+        expect![[r#"
+            st Bar
+            st Foo
+            bn Bar(…)        Bar($1)$0
+            bn Foo {…} Foo { num$1 }$0
+            kw mut
+            kw ref
+        "#]],
+    )
+}
+
+#[test]
 fn completes_in_closure_param() {
     check(
         r#"
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/tests/special.rs b/src/tools/rust-analyzer/crates/ide-completion/src/tests/special.rs
index 84ddff8f617..c438ca78806 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/tests/special.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/tests/special.rs
@@ -1510,3 +1510,28 @@ fn foo<T>() {
         "#]],
     );
 }
+
+#[test]
+fn fn_generic_params_const_param_snippet() {
+    check_edit("const", "fn foo<c$0>() {}", "fn foo<const $1: $0>() {}");
+    check_edit("const", "fn foo<T, c$0>() {}", "fn foo<T, const $1: $0>() {}");
+    check(
+        r#"
+fn foo<T: $0>() {}
+"#,
+        expect![[r#"
+            kw crate::
+            kw self::
+        "#]],
+    );
+    check(
+        r#"
+fn foo<const N: $0>() {}
+"#,
+        expect![[r#"
+            bt u32 u32
+            kw crate::
+            kw self::
+        "#]],
+    );
+}
diff --git a/src/tools/rust-analyzer/crates/ide-completion/src/tests/type_pos.rs b/src/tools/rust-analyzer/crates/ide-completion/src/tests/type_pos.rs
index c7e2d058257..125e11e9e35 100644
--- a/src/tools/rust-analyzer/crates/ide-completion/src/tests/type_pos.rs
+++ b/src/tools/rust-analyzer/crates/ide-completion/src/tests/type_pos.rs
@@ -429,18 +429,18 @@ trait Tr<T> {
 impl Tr<$0
     "#,
         expect![[r#"
-            en Enum                    Enum
-            ma makro!(…) macro_rules! makro
+            en Enum                        Enum
+            ma makro!(…)     macro_rules! makro
             md module
-            sp Self       dyn Tr<{unknown}>
-            st Record                Record
-            st S                          S
-            st Tuple                  Tuple
-            st Unit                    Unit
+            sp Self dyn Tr<{unknown}> + 'static
+            st Record                    Record
+            st S                              S
+            st Tuple                      Tuple
+            st Unit                        Unit
             tt Tr
             tt Trait
-            un Union                  Union
-            bt u32                      u32
+            un Union                      Union
+            bt u32                          u32
             kw crate::
             kw self::
         "#]],
diff --git a/src/tools/rust-analyzer/crates/ide-db/src/syntax_helpers/node_ext.rs b/src/tools/rust-analyzer/crates/ide-db/src/syntax_helpers/node_ext.rs
index cefd8fd4967..e1d140730ed 100644
--- a/src/tools/rust-analyzer/crates/ide-db/src/syntax_helpers/node_ext.rs
+++ b/src/tools/rust-analyzer/crates/ide-db/src/syntax_helpers/node_ext.rs
@@ -265,10 +265,7 @@ pub fn is_pattern_cond(expr: ast::Expr) -> bool {
         ast::Expr::BinExpr(expr)
             if expr.op_kind() == Some(ast::BinaryOp::LogicOp(ast::LogicOp::And)) =>
         {
-            expr.lhs()
-                .map(is_pattern_cond)
-                .or_else(|| expr.rhs().map(is_pattern_cond))
-                .unwrap_or(false)
+            expr.lhs().map_or(false, is_pattern_cond) || expr.rhs().map_or(false, is_pattern_cond)
         }
         ast::Expr::ParenExpr(expr) => expr.expr().is_some_and(is_pattern_cond),
         ast::Expr::LetExpr(_) => true,
diff --git a/src/tools/rust-analyzer/crates/ide-db/src/syntax_helpers/suggest_name.rs b/src/tools/rust-analyzer/crates/ide-db/src/syntax_helpers/suggest_name.rs
index 995bf72dca1..2e03665765f 100644
--- a/src/tools/rust-analyzer/crates/ide-db/src/syntax_helpers/suggest_name.rs
+++ b/src/tools/rust-analyzer/crates/ide-db/src/syntax_helpers/suggest_name.rs
@@ -473,7 +473,7 @@ mod tests {
             frange.range,
             "selection is not an expression(yet contained in one)"
         );
-        let name = NameGenerator::default().for_variable(&expr, &sema);
+        let name = salsa::attach(sema.db, || NameGenerator::default().for_variable(&expr, &sema));
         assert_eq!(&name, expected);
     }
 
diff --git a/src/tools/rust-analyzer/crates/ide-diagnostics/src/handlers/missing_lifetime.rs b/src/tools/rust-analyzer/crates/ide-diagnostics/src/handlers/missing_lifetime.rs
index 76b30745a04..b07f9e68f63 100644
--- a/src/tools/rust-analyzer/crates/ide-diagnostics/src/handlers/missing_lifetime.rs
+++ b/src/tools/rust-analyzer/crates/ide-diagnostics/src/handlers/missing_lifetime.rs
@@ -88,4 +88,16 @@ fn bar<const F: Foo>() {}
         "#,
         );
     }
+
+    #[test]
+    fn fn_traits() {
+        check_diagnostics(
+            r#"
+//- minicore: fn
+struct WithLifetime<'a>(&'a ());
+
+fn foo<T: Fn(WithLifetime) -> WithLifetime>() {}
+        "#,
+        );
+    }
 }
diff --git a/src/tools/rust-analyzer/crates/ide-diagnostics/src/handlers/missing_unsafe.rs b/src/tools/rust-analyzer/crates/ide-diagnostics/src/handlers/missing_unsafe.rs
index 4bb64747f5b..029ed18a4d3 100644
--- a/src/tools/rust-analyzer/crates/ide-diagnostics/src/handlers/missing_unsafe.rs
+++ b/src/tools/rust-analyzer/crates/ide-diagnostics/src/handlers/missing_unsafe.rs
@@ -442,6 +442,49 @@ fn main() {
     }
 
     #[test]
+    fn raw_deref_on_union_field() {
+        check_diagnostics(
+            r#"
+fn main() {
+
+    union U {
+        a: u8
+    }
+    let x = U { a: 3 };
+
+    let a = &raw mut x.a;
+
+    union U1 {
+        a: u8
+    }
+    let x = U1 { a: 3 };
+
+    let a = x.a;
+         // ^^^ 💡 error: access to union field is unsafe and requires an unsafe function or block
+
+
+    let b = &raw const x.a;
+
+    let tmp = Vec::from([1, 2, 3]);
+
+    let c = &raw const tmp[x.a];
+                        // ^^^ 💡 error: access to union field is unsafe and requires an unsafe function or block
+
+    union URef {
+        p: &'static mut i32,
+    }
+
+    fn deref_union_field(u: URef) {
+        // Not an assignment but an access to the union field!
+        *(u.p) = 13;
+       // ^^^ 💡 error: access to union field is unsafe and requires an unsafe function or block
+    }
+}
+"#,
+        )
+    }
+
+    #[test]
     fn unsafe_expr_as_an_argument_of_a_method_call() {
         check_fix(
             r#"
diff --git a/src/tools/rust-analyzer/crates/ide-diagnostics/src/handlers/unused_variables.rs b/src/tools/rust-analyzer/crates/ide-diagnostics/src/handlers/unused_variables.rs
index e6bbff05f7e..84e63acbc04 100644
--- a/src/tools/rust-analyzer/crates/ide-diagnostics/src/handlers/unused_variables.rs
+++ b/src/tools/rust-analyzer/crates/ide-diagnostics/src/handlers/unused_variables.rs
@@ -6,7 +6,7 @@ use ide_db::{
     label::Label,
     source_change::SourceChange,
 };
-use syntax::{Edition, TextRange};
+use syntax::{AstNode, Edition, TextRange, ToSmolStr};
 
 use crate::{Diagnostic, DiagnosticCode, DiagnosticsContext};
 
@@ -24,15 +24,21 @@ pub(crate) fn unused_variables(
     }
     let diagnostic_range = ctx.sema.diagnostics_display_range(ast);
     // The range for the Actual Name. We don't want to replace the entire declaration. Using the diagnostic range causes issues within in Array Destructuring.
-    let name_range = d
-        .local
-        .primary_source(ctx.sema.db)
+    let primary_source = d.local.primary_source(ctx.sema.db);
+    let name_range = primary_source
         .name()
         .map(|v| v.syntax().original_file_range_rooted(ctx.sema.db))
         .filter(|it| {
             Some(it.file_id) == ast.file_id.file_id()
                 && diagnostic_range.range.contains_range(it.range)
         });
+    let is_shorthand_field = primary_source
+        .source
+        .value
+        .left()
+        .and_then(|name| name.syntax().parent())
+        .and_then(syntax::ast::RecordPatField::cast)
+        .is_some_and(|field| field.colon_token().is_none());
     let var_name = d.local.name(ctx.sema.db);
     Some(
         Diagnostic::new_with_syntax_node_ptr(
@@ -48,6 +54,7 @@ pub(crate) fn unused_variables(
                 it.range,
                 diagnostic_range,
                 ast.file_id.is_macro(),
+                is_shorthand_field,
                 ctx.edition,
             )
         })),
@@ -60,24 +67,24 @@ fn fixes(
     name_range: TextRange,
     diagnostic_range: FileRange,
     is_in_marco: bool,
+    is_shorthand_field: bool,
     edition: Edition,
 ) -> Option<Vec<Assist>> {
     if is_in_marco {
         return None;
     }
+    let name = var_name.display(db, edition).to_smolstr();
+    let name = name.strip_prefix("r#").unwrap_or(&name);
+    let new_name = if is_shorthand_field { format!("{name}: _{name}") } else { format!("_{name}") };
 
     Some(vec![Assist {
         id: AssistId::quick_fix("unscore_unused_variable_name"),
-        label: Label::new(format!(
-            "Rename unused {} to _{}",
-            var_name.display(db, edition),
-            var_name.display(db, edition)
-        )),
+        label: Label::new(format!("Rename unused {name} to {new_name}")),
         group: None,
         target: diagnostic_range.range,
         source_change: Some(SourceChange::from_text_edit(
             diagnostic_range.file_id,
-            TextEdit::replace(name_range, format!("_{}", var_name.display(db, edition))),
+            TextEdit::replace(name_range, new_name),
         )),
         command: None,
     }])
@@ -220,13 +227,26 @@ struct Foo { f1: i32, f2: i64 }
 fn main() {
     let f = Foo { f1: 0, f2: 0 };
     match f {
-        Foo { _f1, f2 } => {
+        Foo { f1: _f1, f2 } => {
             _ = f2;
         }
     }
 }
 "#,
         );
+
+        check_fix(
+            r#"
+fn main() {
+    let $0r#type = 2;
+}
+"#,
+            r#"
+fn main() {
+    let _type = 2;
+}
+"#,
+        );
     }
 
     #[test]
@@ -263,6 +283,46 @@ fn main() {
         );
     }
 
+    #[test]
+    fn unused_variable_in_record_field() {
+        check_fix(
+            r#"
+struct S { field : u32 }
+fn main() {
+    let s = S { field : 2 };
+    let S { field: $0x } = s
+}
+"#,
+            r#"
+struct S { field : u32 }
+fn main() {
+    let s = S { field : 2 };
+    let S { field: _x } = s
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn unused_variable_in_shorthand_record_field() {
+        check_fix(
+            r#"
+struct S { field : u32 }
+fn main() {
+    let s = S { field : 2 };
+    let S { $0field } = s
+}
+"#,
+            r#"
+struct S { field : u32 }
+fn main() {
+    let s = S { field : 2 };
+    let S { field: _field } = s
+}
+"#,
+        );
+    }
+
     // regression test as we used to panic in this scenario
     #[test]
     fn unknown_struct_pattern_param_type() {
diff --git a/src/tools/rust-analyzer/crates/ide/src/goto_type_definition.rs b/src/tools/rust-analyzer/crates/ide/src/goto_type_definition.rs
index ffd144a827e..ae208fe1b56 100644
--- a/src/tools/rust-analyzer/crates/ide/src/goto_type_definition.rs
+++ b/src/tools/rust-analyzer/crates/ide/src/goto_type_definition.rs
@@ -88,7 +88,7 @@ pub(crate) fn goto_type_definition(
                             ast::Pat(it) => sema.type_of_pat(&it)?.original,
                             ast::SelfParam(it) => sema.type_of_self(&it)?,
                             ast::Type(it) => sema.resolve_type(&it)?,
-                            ast::RecordField(it) => sema.to_def(&it)?.ty(db),
+                            ast::RecordField(it) => sema.to_def(&it)?.ty(db).to_type(db),
                             // can't match on RecordExprField directly as `ast::Expr` will match an iteration too early otherwise
                             ast::NameRef(it) => {
                                 if let Some(record_field) = ast::RecordExprField::for_name_ref(&it) {
diff --git a/src/tools/rust-analyzer/crates/ide/src/hover.rs b/src/tools/rust-analyzer/crates/ide/src/hover.rs
index 03b9b367751..c4fb6d1a5b4 100644
--- a/src/tools/rust-analyzer/crates/ide/src/hover.rs
+++ b/src/tools/rust-analyzer/crates/ide/src/hover.rs
@@ -440,7 +440,7 @@ pub(crate) fn hover_for_definition(
         Definition::Local(it) => Some(it.ty(db)),
         Definition::GenericParam(hir::GenericParam::ConstParam(it)) => Some(it.ty(db)),
         Definition::GenericParam(hir::GenericParam::TypeParam(it)) => Some(it.ty(db)),
-        Definition::Field(field) => Some(field.ty(db)),
+        Definition::Field(field) => Some(field.ty(db).to_type(db)),
         Definition::TupleField(it) => Some(it.ty(db)),
         Definition::Function(it) => Some(it.ty(db)),
         Definition::Adt(it) => Some(it.ty(db)),
@@ -602,7 +602,7 @@ fn goto_type_action_for_def(
 
     let ty = match def {
         Definition::Local(it) => Some(it.ty(db)),
-        Definition::Field(field) => Some(field.ty(db)),
+        Definition::Field(field) => Some(field.ty(db).to_type(db)),
         Definition::TupleField(field) => Some(field.ty(db)),
         Definition::Const(it) => Some(it.ty(db)),
         Definition::Static(it) => Some(it.ty(db)),
diff --git a/src/tools/rust-analyzer/crates/ide/src/hover/render.rs b/src/tools/rust-analyzer/crates/ide/src/hover/render.rs
index 65375ed8f78..c5d695ccec3 100644
--- a/src/tools/rust-analyzer/crates/ide/src/hover/render.rs
+++ b/src/tools/rust-analyzer/crates/ide/src/hover/render.rs
@@ -692,14 +692,14 @@ pub(super) fn definition(
         }
         let drop_info = match def {
             Definition::Field(field) => {
-                DropInfo { drop_glue: field.ty(db).drop_glue(db), has_dtor: None }
+                DropInfo { drop_glue: field.ty(db).to_type(db).drop_glue(db), has_dtor: None }
             }
             Definition::Adt(Adt::Struct(strukt)) => {
                 let struct_drop_glue = strukt.ty_placeholders(db).drop_glue(db);
                 let mut fields_drop_glue = strukt
                     .fields(db)
                     .iter()
-                    .map(|field| field.ty(db).drop_glue(db))
+                    .map(|field| field.ty(db).to_type(db).drop_glue(db))
                     .max()
                     .unwrap_or(DropGlue::None);
                 let has_dtor = match (fields_drop_glue, struct_drop_glue) {
@@ -727,7 +727,7 @@ pub(super) fn definition(
                         variant
                             .fields(db)
                             .iter()
-                            .map(|field| field.ty(db).drop_glue(db))
+                            .map(|field| field.ty(db).to_type(db).drop_glue(db))
                             .max()
                             .unwrap_or(DropGlue::None)
                     })
@@ -742,7 +742,7 @@ pub(super) fn definition(
                 let fields_drop_glue = variant
                     .fields(db)
                     .iter()
-                    .map(|field| field.ty(db).drop_glue(db))
+                    .map(|field| field.ty(db).to_type(db).drop_glue(db))
                     .max()
                     .unwrap_or(DropGlue::None);
                 DropInfo { drop_glue: fields_drop_glue, has_dtor: None }
diff --git a/src/tools/rust-analyzer/crates/ide/src/hover/tests.rs b/src/tools/rust-analyzer/crates/ide/src/hover/tests.rs
index 1ea11a215f8..8bc0b3f6ab3 100644
--- a/src/tools/rust-analyzer/crates/ide/src/hover/tests.rs
+++ b/src/tools/rust-analyzer/crates/ide/src/hover/tests.rs
@@ -4797,6 +4797,48 @@ fn main() {
 }
 
 #[test]
+fn const_generic_negative_literal_macro_expansion() {
+    // Test that negative literals work correctly in const generics
+    // when used through macro expansion. This ensures the transcriber
+    // doesn't wrap negative literals in parentheses, which would create
+    // invalid syntax like Foo::<(-1)> instead of Foo::<-1>.
+    check(
+        r#"
+struct Foo<const I: i16> {
+    pub value: i16,
+}
+
+impl<const I: i16> Foo<I> {
+    pub fn new(value: i16) -> Self {
+        Self { value }
+    }
+}
+
+macro_rules! create_foo {
+    ($val:expr) => {
+        Foo::<$val>::new($val)
+    };
+}
+
+fn main() {
+    let v$0alue = create_foo!(-1);
+}
+"#,
+        expect![[r#"
+            *value*
+
+            ```rust
+            let value: Foo<-1>
+            ```
+
+            ---
+
+            size = 2, align = 2, no Drop
+        "#]],
+    );
+}
+
+#[test]
 fn hover_self_param_shows_type() {
     check(
         r#"
diff --git a/src/tools/rust-analyzer/crates/ide/src/inlay_hints/bind_pat.rs b/src/tools/rust-analyzer/crates/ide/src/inlay_hints/bind_pat.rs
index 104740cbbf7..b7c12413960 100644
--- a/src/tools/rust-analyzer/crates/ide/src/inlay_hints/bind_pat.rs
+++ b/src/tools/rust-analyzer/crates/ide/src/inlay_hints/bind_pat.rs
@@ -380,7 +380,7 @@ fn main() {
     let foo = foo4();
      // ^^^ &dyn Fn(f64, f64) -> u32
     let foo = foo5();
-     // ^^^ &dyn Fn(&dyn Fn(f64, f64) -> u32, f64) -> u32
+     // ^^^ &dyn Fn(&(dyn Fn(f64, f64) -> u32 + 'static), f64) -> u32
     let foo = foo6();
      // ^^^ impl Fn(f64, f64) -> u32
     let foo = foo7();
diff --git a/src/tools/rust-analyzer/crates/ide/src/inlay_hints/closing_brace.rs b/src/tools/rust-analyzer/crates/ide/src/inlay_hints/closing_brace.rs
index e80c9dc9d47..9d246eda57e 100644
--- a/src/tools/rust-analyzer/crates/ide/src/inlay_hints/closing_brace.rs
+++ b/src/tools/rust-analyzer/crates/ide/src/inlay_hints/closing_brace.rs
@@ -191,7 +191,7 @@ impl Tr for () {
 //^ impl Tr for ()
 impl dyn Tr {
   }
-//^ impl dyn Tr
+//^ impl dyn Tr + 'static
 
 static S0: () = 0;
 static S1: () = {};
diff --git a/src/tools/rust-analyzer/crates/ide/src/signature_help.rs b/src/tools/rust-analyzer/crates/ide/src/signature_help.rs
index f45d096ac19..e74d997e97c 100644
--- a/src/tools/rust-analyzer/crates/ide/src/signature_help.rs
+++ b/src/tools/rust-analyzer/crates/ide/src/signature_help.rs
@@ -526,7 +526,7 @@ fn signature_help_for_tuple_struct_pat(
         pat.syntax(),
         token,
         pat.fields(),
-        fields.into_iter().map(|it| it.ty(db)),
+        fields.into_iter().map(|it| it.ty(db).to_type(db)),
         display_target,
     ))
 }
diff --git a/src/tools/rust-analyzer/crates/ide/src/static_index.rs b/src/tools/rust-analyzer/crates/ide/src/static_index.rs
index 8214b4d1de2..9911b85799b 100644
--- a/src/tools/rust-analyzer/crates/ide/src/static_index.rs
+++ b/src/tools/rust-analyzer/crates/ide/src/static_index.rs
@@ -278,7 +278,7 @@ impl StaticIndex<'_> {
         for token in tokens {
             let range = token.text_range();
             let node = token.parent().unwrap();
-            match get_definitions(&sema, token.clone()) {
+            match salsa::attach(self.db, || get_definitions(&sema, token.clone())) {
                 Some(it) => {
                     for i in it {
                         add_token(i, range, &node);
diff --git a/src/tools/rust-analyzer/crates/ide/src/syntax_highlighting/test_data/highlight_unsafe.html b/src/tools/rust-analyzer/crates/ide/src/syntax_highlighting/test_data/highlight_unsafe.html
index 828b8f762c5..8339daf3246 100644
--- a/src/tools/rust-analyzer/crates/ide/src/syntax_highlighting/test_data/highlight_unsafe.html
+++ b/src/tools/rust-analyzer/crates/ide/src/syntax_highlighting/test_data/highlight_unsafe.html
@@ -96,7 +96,7 @@ pre                 { color: #DCDCCC; background: #3F3F3F; font-size: 22px; padd
 
         <span class="variable">u</span><span class="operator">.</span><span class="field unsafe">field</span><span class="semicolon">;</span>
         <span class="operator">&</span><span class="variable">u</span><span class="operator">.</span><span class="field unsafe">field</span><span class="semicolon">;</span>
-        <span class="operator">&</span><span class="keyword">raw</span> <span class="keyword const">const</span> <span class="variable">u</span><span class="operator">.</span><span class="field unsafe">field</span><span class="semicolon">;</span>
+        <span class="operator">&</span><span class="keyword">raw</span> <span class="keyword const">const</span> <span class="variable">u</span><span class="operator">.</span><span class="field">field</span><span class="semicolon">;</span>
         <span class="comment">// this should be safe!</span>
         <span class="keyword">let</span> <span class="union">Union</span> <span class="brace">{</span> <span class="field">field</span><span class="colon">:</span> <span class="punctuation">_</span> <span class="brace">}</span><span class="semicolon">;</span>
         <span class="comment">// but not these</span>
diff --git a/src/tools/rust-analyzer/crates/ide/src/view_memory_layout.rs b/src/tools/rust-analyzer/crates/ide/src/view_memory_layout.rs
index 950f3f6c647..ddd58a0a3c9 100644
--- a/src/tools/rust-analyzer/crates/ide/src/view_memory_layout.rs
+++ b/src/tools/rust-analyzer/crates/ide/src/view_memory_layout.rs
@@ -94,14 +94,14 @@ pub(crate) fn view_memory_layout(
     let def = get_definition(&sema, token)?;
 
     let ty = match def {
-        Definition::Adt(it) => it.ty(db),
-        Definition::TypeAlias(it) => it.ty(db),
+        Definition::Adt(it) => salsa::attach(db, || it.ty(db)),
+        Definition::TypeAlias(it) => salsa::attach(db, || it.ty(db)),
         Definition::BuiltinType(it) => it.ty(db),
         Definition::SelfType(it) => it.self_ty(db),
         Definition::Local(it) => it.ty(db),
-        Definition::Field(it) => it.ty(db),
-        Definition::Const(it) => it.ty(db),
-        Definition::Static(it) => it.ty(db),
+        Definition::Field(it) => salsa::attach(db, || it.ty(db).to_type(db)),
+        Definition::Const(it) => salsa::attach(db, || it.ty(db)),
+        Definition::Static(it) => salsa::attach(db, || it.ty(db)),
         _ => return None,
     };
 
diff --git a/src/tools/rust-analyzer/crates/intern/src/symbol/symbols.rs b/src/tools/rust-analyzer/crates/intern/src/symbol/symbols.rs
index 1db4f8ecd6b..920bdd9568f 100644
--- a/src/tools/rust-analyzer/crates/intern/src/symbol/symbols.rs
+++ b/src/tools/rust-analyzer/crates/intern/src/symbol/symbols.rs
@@ -516,4 +516,5 @@ define_symbols! {
     flags,
     precision,
     width,
+    never_type_fallback,
 }
diff --git a/src/tools/rust-analyzer/crates/mbe/src/expander/transcriber.rs b/src/tools/rust-analyzer/crates/mbe/src/expander/transcriber.rs
index 2c046df10f5..3e4ab8bdc1d 100644
--- a/src/tools/rust-analyzer/crates/mbe/src/expander/transcriber.rs
+++ b/src/tools/rust-analyzer/crates/mbe/src/expander/transcriber.rs
@@ -401,7 +401,19 @@ fn expand_var(
                     let sub = sub.strip_invisible();
                     let mut span = id;
                     marker(&mut span);
-                    let wrap_in_parens = !matches!(sub.flat_tokens(), [tt::TokenTree::Leaf(_)])
+
+                    // Check if this is a simple negative literal (MINUS + LITERAL)
+                    // that should not be wrapped in parentheses
+                    let is_negative_literal = matches!(
+                        sub.flat_tokens(),
+                        [
+                            tt::TokenTree::Leaf(tt::Leaf::Punct(tt::Punct { char: '-', .. })),
+                            tt::TokenTree::Leaf(tt::Leaf::Literal(_))
+                        ]
+                    );
+
+                    let wrap_in_parens = !is_negative_literal
+                        && !matches!(sub.flat_tokens(), [tt::TokenTree::Leaf(_)])
                         && sub.try_into_subtree().is_none_or(|it| {
                             it.top_subtree().delimiter.kind == tt::DelimiterKind::Invisible
                         });
diff --git a/src/tools/rust-analyzer/crates/project-model/src/build_dependencies.rs b/src/tools/rust-analyzer/crates/project-model/src/build_dependencies.rs
index 203173c11be..5eda5af3ace 100644
--- a/src/tools/rust-analyzer/crates/project-model/src/build_dependencies.rs
+++ b/src/tools/rust-analyzer/crates/project-model/src/build_dependencies.rs
@@ -9,7 +9,7 @@
 use std::{cell::RefCell, io, mem, process::Command};
 
 use base_db::Env;
-use cargo_metadata::{Message, camino::Utf8Path};
+use cargo_metadata::{Message, PackageId, camino::Utf8Path};
 use cfg::CfgAtom;
 use itertools::Itertools;
 use la_arena::ArenaMap;
@@ -18,6 +18,7 @@ use rustc_hash::{FxHashMap, FxHashSet};
 use serde::Deserialize as _;
 use stdx::never;
 use toolchain::Tool;
+use triomphe::Arc;
 
 use crate::{
     CargoConfig, CargoFeatures, CargoWorkspace, InvocationStrategy, ManifestPath, Package, Sysroot,
@@ -284,7 +285,7 @@ impl WorkspaceBuildScripts {
         // NB: Cargo.toml could have been modified between `cargo metadata` and
         // `cargo check`. We shouldn't assume that package ids we see here are
         // exactly those from `config`.
-        let mut by_id: FxHashMap<String, Package> = FxHashMap::default();
+        let mut by_id: FxHashMap<Arc<PackageId>, Package> = FxHashMap::default();
         for package in workspace.packages() {
             outputs.insert(package, BuildScriptOutput::default());
             by_id.insert(workspace[package].id.clone(), package);
@@ -323,7 +324,7 @@ impl WorkspaceBuildScripts {
         // ideally this would be something like:
         // with_output_for: impl FnMut(&str, dyn FnOnce(&mut BuildScriptOutput)),
         // but owned trait objects aren't a thing
-        mut with_output_for: impl FnMut(&str, &mut dyn FnMut(&str, &mut BuildScriptOutput)),
+        mut with_output_for: impl FnMut(&PackageId, &mut dyn FnMut(&str, &mut BuildScriptOutput)),
         progress: &dyn Fn(String),
     ) -> io::Result<Option<String>> {
         let errors = RefCell::new(String::new());
@@ -346,7 +347,7 @@ impl WorkspaceBuildScripts {
 
                 match message {
                     Message::BuildScriptExecuted(mut message) => {
-                        with_output_for(&message.package_id.repr, &mut |name, data| {
+                        with_output_for(&message.package_id, &mut |name, data| {
                             progress(format!("build script {name} run"));
                             let cfgs = {
                                 let mut acc = Vec::new();
@@ -377,7 +378,7 @@ impl WorkspaceBuildScripts {
                         });
                     }
                     Message::CompilerArtifact(message) => {
-                        with_output_for(&message.package_id.repr, &mut |name, data| {
+                        with_output_for(&message.package_id, &mut |name, data| {
                             progress(format!("proc-macro {name} built"));
                             if data.proc_macro_dylib_path == ProcMacroDylibPath::NotBuilt {
                                 data.proc_macro_dylib_path = ProcMacroDylibPath::NotProcMacro;
diff --git a/src/tools/rust-analyzer/crates/project-model/src/cargo_workspace.rs b/src/tools/rust-analyzer/crates/project-model/src/cargo_workspace.rs
index e613fd590c7..adc0cc50941 100644
--- a/src/tools/rust-analyzer/crates/project-model/src/cargo_workspace.rs
+++ b/src/tools/rust-analyzer/crates/project-model/src/cargo_workspace.rs
@@ -5,7 +5,7 @@ use std::str::from_utf8;
 
 use anyhow::Context;
 use base_db::Env;
-use cargo_metadata::{CargoOpt, MetadataCommand};
+use cargo_metadata::{CargoOpt, MetadataCommand, PackageId};
 use la_arena::{Arena, Idx};
 use paths::{AbsPath, AbsPathBuf, Utf8Path, Utf8PathBuf};
 use rustc_hash::{FxHashMap, FxHashSet};
@@ -14,6 +14,7 @@ use serde_json::from_value;
 use span::Edition;
 use stdx::process::spawn_with_streaming_output;
 use toolchain::Tool;
+use triomphe::Arc;
 
 use crate::cargo_config_file::make_lockfile_copy;
 use crate::{CfgOverrides, InvocationStrategy};
@@ -155,8 +156,8 @@ pub struct PackageData {
     pub features: FxHashMap<String, Vec<String>>,
     /// List of features enabled on this package
     pub active_features: Vec<String>,
-    /// String representation of package id
-    pub id: String,
+    /// Package id
+    pub id: Arc<PackageId>,
     /// Authors as given in the `Cargo.toml`
     pub authors: Vec<String>,
     /// Description as given in the `Cargo.toml`
@@ -173,6 +174,10 @@ pub struct PackageData {
     pub rust_version: Option<semver::Version>,
     /// The contents of [package.metadata.rust-analyzer]
     pub metadata: RustAnalyzerPackageMetaData,
+    /// If this package is a member of the workspace, store all direct and transitive
+    /// dependencies as long as they are workspace members, to track dependency relationships
+    /// between members.
+    pub all_member_deps: Option<FxHashSet<Package>>,
 }
 
 #[derive(Deserialize, Default, Debug, Clone, Eq, PartialEq)]
@@ -334,6 +339,8 @@ impl CargoWorkspace {
         let mut is_virtual_workspace = true;
         let mut requires_rustc_private = false;
 
+        let mut members = FxHashSet::default();
+
         meta.packages.sort_by(|a, b| a.id.cmp(&b.id));
         for meta_pkg in meta.packages {
             let cargo_metadata::Package {
@@ -356,6 +363,7 @@ impl CargoWorkspace {
                 rust_version,
                 ..
             } = meta_pkg;
+            let id = Arc::new(id);
             let meta = from_value::<PackageMetadata>(metadata).unwrap_or_default();
             let edition = match edition {
                 cargo_metadata::Edition::E2015 => Edition::Edition2015,
@@ -375,7 +383,7 @@ impl CargoWorkspace {
             let manifest = ManifestPath::try_from(AbsPathBuf::assert(manifest_path)).unwrap();
             is_virtual_workspace &= manifest != ws_manifest_path;
             let pkg = packages.alloc(PackageData {
-                id: id.repr.clone(),
+                id: id.clone(),
                 name: name.to_string(),
                 version,
                 manifest: manifest.clone(),
@@ -395,7 +403,11 @@ impl CargoWorkspace {
                 features: features.into_iter().collect(),
                 active_features: Vec::new(),
                 metadata: meta.rust_analyzer.unwrap_or_default(),
+                all_member_deps: None,
             });
+            if is_member {
+                members.insert(pkg);
+            }
             let pkg_data = &mut packages[pkg];
             requires_rustc_private |= pkg_data.metadata.rustc_private;
             pkg_by_id.insert(id, pkg);
@@ -440,6 +452,43 @@ impl CargoWorkspace {
                 .extend(node.features.into_iter().map(|it| it.to_string()));
         }
 
+        fn saturate_all_member_deps(
+            packages: &mut Arena<PackageData>,
+            to_visit: Package,
+            visited: &mut FxHashSet<Package>,
+            members: &FxHashSet<Package>,
+        ) {
+            let pkg_data = &mut packages[to_visit];
+
+            if !visited.insert(to_visit) {
+                return;
+            }
+
+            let deps: Vec<_> = pkg_data
+                .dependencies
+                .iter()
+                .filter_map(|dep| {
+                    let pkg = dep.pkg;
+                    if members.contains(&pkg) { Some(pkg) } else { None }
+                })
+                .collect();
+
+            let mut all_member_deps = FxHashSet::from_iter(deps.iter().copied());
+            for dep in deps {
+                saturate_all_member_deps(packages, dep, visited, members);
+                if let Some(transitives) = &packages[dep].all_member_deps {
+                    all_member_deps.extend(transitives);
+                }
+            }
+
+            packages[to_visit].all_member_deps = Some(all_member_deps);
+        }
+
+        let mut visited = FxHashSet::default();
+        for member in members.iter() {
+            saturate_all_member_deps(&mut packages, *member, &mut visited, &members);
+        }
+
         CargoWorkspace {
             packages,
             targets,
diff --git a/src/tools/rust-analyzer/crates/rust-analyzer/src/config.rs b/src/tools/rust-analyzer/crates/rust-analyzer/src/config.rs
index 6b489d51143..a88d228fcb6 100644
--- a/src/tools/rust-analyzer/crates/rust-analyzer/src/config.rs
+++ b/src/tools/rust-analyzer/crates/rust-analyzer/src/config.rs
@@ -267,6 +267,8 @@ config_data! {
         inlayHints_lifetimeElisionHints_useParameterNames: bool = false,
 
         /// Maximum length for inlay hints. Set to null to have an unlimited length.
+        ///
+        /// **Note:** This is mostly a hint, and we don't guarantee to strictly follow the limit.
         inlayHints_maxLength: Option<usize> = Some(25),
 
         /// Show function parameter name inlay hints at the call site.
diff --git a/src/tools/rust-analyzer/crates/rust-analyzer/src/diagnostics.rs b/src/tools/rust-analyzer/crates/rust-analyzer/src/diagnostics.rs
index ee50237c405..4bfad98b399 100644
--- a/src/tools/rust-analyzer/crates/rust-analyzer/src/diagnostics.rs
+++ b/src/tools/rust-analyzer/crates/rust-analyzer/src/diagnostics.rs
@@ -120,6 +120,29 @@ impl DiagnosticCollection {
         }
     }
 
+    pub(crate) fn clear_check_older_than_for_package(
+        &mut self,
+        flycheck_id: usize,
+        package_id: Arc<PackageId>,
+        generation: DiagnosticsGeneration,
+    ) {
+        let Some(check) = self.check.get_mut(flycheck_id) else {
+            return;
+        };
+        let package_id = Some(package_id);
+        let Some((_, checks)) = check
+            .per_package
+            .extract_if(|k, v| *k == package_id && v.generation < generation)
+            .next()
+        else {
+            return;
+        };
+        self.changes.extend(checks.per_file.into_keys());
+        if let Some(fixes) = Arc::make_mut(&mut self.check_fixes).get_mut(flycheck_id) {
+            fixes.remove(&package_id);
+        }
+    }
+
     pub(crate) fn clear_native_for(&mut self, file_id: FileId) {
         self.native_syntax.remove(&file_id);
         self.native_semantic.remove(&file_id);
diff --git a/src/tools/rust-analyzer/crates/rust-analyzer/src/flycheck.rs b/src/tools/rust-analyzer/crates/rust-analyzer/src/flycheck.rs
index 315c45d5b63..cded34be14a 100644
--- a/src/tools/rust-analyzer/crates/rust-analyzer/src/flycheck.rs
+++ b/src/tools/rust-analyzer/crates/rust-analyzer/src/flycheck.rs
@@ -180,17 +180,27 @@ impl FlycheckHandle {
     pub(crate) fn restart_workspace(&self, saved_file: Option<AbsPathBuf>) {
         let generation = self.generation.fetch_add(1, Ordering::Relaxed) + 1;
         self.sender
-            .send(StateChange::Restart { generation, package: None, saved_file, target: None })
+            .send(StateChange::Restart {
+                generation,
+                scope: FlycheckScope::Workspace,
+                saved_file,
+                target: None,
+            })
             .unwrap();
     }
 
     /// Schedule a re-start of the cargo check worker to do a package wide check.
-    pub(crate) fn restart_for_package(&self, package: String, target: Option<Target>) {
+    pub(crate) fn restart_for_package(
+        &self,
+        package: Arc<PackageId>,
+        target: Option<Target>,
+        workspace_deps: Option<FxHashSet<Arc<PackageId>>>,
+    ) {
         let generation = self.generation.fetch_add(1, Ordering::Relaxed) + 1;
         self.sender
             .send(StateChange::Restart {
                 generation,
-                package: Some(package),
+                scope: FlycheckScope::Package { package, workspace_deps },
                 saved_file: None,
                 target,
             })
@@ -213,8 +223,13 @@ impl FlycheckHandle {
 
 #[derive(Debug)]
 pub(crate) enum ClearDiagnosticsKind {
-    All,
-    OlderThan(DiagnosticsGeneration),
+    All(ClearScope),
+    OlderThan(DiagnosticsGeneration, ClearScope),
+}
+
+#[derive(Debug)]
+pub(crate) enum ClearScope {
+    Workspace,
     Package(Arc<PackageId>),
 }
 
@@ -275,10 +290,15 @@ pub(crate) enum Progress {
     DidFailToRestart(String),
 }
 
+enum FlycheckScope {
+    Workspace,
+    Package { package: Arc<PackageId>, workspace_deps: Option<FxHashSet<Arc<PackageId>>> },
+}
+
 enum StateChange {
     Restart {
         generation: DiagnosticsGeneration,
-        package: Option<String>,
+        scope: FlycheckScope,
         saved_file: Option<AbsPathBuf>,
         target: Option<Target>,
     },
@@ -298,6 +318,7 @@ struct FlycheckActor {
     /// or the project root of the project.
     root: Arc<AbsPathBuf>,
     sysroot_root: Option<AbsPathBuf>,
+    scope: FlycheckScope,
     /// CargoHandle exists to wrap around the communication needed to be able to
     /// run `cargo check` without blocking. Currently the Rust standard library
     /// doesn't provide a way to read sub-process output without blocking, so we
@@ -343,6 +364,7 @@ impl FlycheckActor {
             config,
             sysroot_root,
             root: Arc::new(workspace_root),
+            scope: FlycheckScope::Workspace,
             manifest_path,
             command_handle: None,
             command_receiver: None,
@@ -376,7 +398,7 @@ impl FlycheckActor {
                 }
                 Event::RequestStateChange(StateChange::Restart {
                     generation,
-                    package,
+                    scope,
                     saved_file,
                     target,
                 }) => {
@@ -389,11 +411,11 @@ impl FlycheckActor {
                         }
                     }
 
+                    let command = self.check_command(&scope, saved_file.as_deref(), target);
+                    self.scope = scope;
                     self.generation = generation;
 
-                    let Some(command) =
-                        self.check_command(package.as_deref(), saved_file.as_deref(), target)
-                    else {
+                    let Some(command) = command else {
                         continue;
                     };
 
@@ -435,19 +457,55 @@ impl FlycheckActor {
                         tracing::trace!(flycheck_id = self.id, "clearing diagnostics");
                         // We finished without receiving any diagnostics.
                         // Clear everything for good measure
-                        self.send(FlycheckMessage::ClearDiagnostics {
-                            id: self.id,
-                            kind: ClearDiagnosticsKind::All,
-                        });
+                        match &self.scope {
+                            FlycheckScope::Workspace => {
+                                self.send(FlycheckMessage::ClearDiagnostics {
+                                    id: self.id,
+                                    kind: ClearDiagnosticsKind::All(ClearScope::Workspace),
+                                });
+                            }
+                            FlycheckScope::Package { package, workspace_deps } => {
+                                for pkg in
+                                    std::iter::once(package).chain(workspace_deps.iter().flatten())
+                                {
+                                    self.send(FlycheckMessage::ClearDiagnostics {
+                                        id: self.id,
+                                        kind: ClearDiagnosticsKind::All(ClearScope::Package(
+                                            pkg.clone(),
+                                        )),
+                                    });
+                                }
+                            }
+                        }
                     } else if res.is_ok() {
                         // We clear diagnostics for packages on
                         // `[CargoCheckMessage::CompilerArtifact]` but there seem to be setups where
                         // cargo may not report an artifact to our runner at all. To handle such
                         // cases, clear stale diagnostics when flycheck completes successfully.
-                        self.send(FlycheckMessage::ClearDiagnostics {
-                            id: self.id,
-                            kind: ClearDiagnosticsKind::OlderThan(self.generation),
-                        });
+                        match &self.scope {
+                            FlycheckScope::Workspace => {
+                                self.send(FlycheckMessage::ClearDiagnostics {
+                                    id: self.id,
+                                    kind: ClearDiagnosticsKind::OlderThan(
+                                        self.generation,
+                                        ClearScope::Workspace,
+                                    ),
+                                });
+                            }
+                            FlycheckScope::Package { package, workspace_deps } => {
+                                for pkg in
+                                    std::iter::once(package).chain(workspace_deps.iter().flatten())
+                                {
+                                    self.send(FlycheckMessage::ClearDiagnostics {
+                                        id: self.id,
+                                        kind: ClearDiagnosticsKind::OlderThan(
+                                            self.generation,
+                                            ClearScope::Package(pkg.clone()),
+                                        ),
+                                    });
+                                }
+                            }
+                        }
                     }
                     self.clear_diagnostics_state();
 
@@ -475,7 +533,7 @@ impl FlycheckActor {
                             );
                             self.send(FlycheckMessage::ClearDiagnostics {
                                 id: self.id,
-                                kind: ClearDiagnosticsKind::Package(package_id),
+                                kind: ClearDiagnosticsKind::All(ClearScope::Package(package_id)),
                             });
                         }
                     }
@@ -498,7 +556,9 @@ impl FlycheckActor {
                                 );
                                 self.send(FlycheckMessage::ClearDiagnostics {
                                     id: self.id,
-                                    kind: ClearDiagnosticsKind::Package(package_id.clone()),
+                                    kind: ClearDiagnosticsKind::All(ClearScope::Package(
+                                        package_id.clone(),
+                                    )),
                                 });
                             }
                         } else if self.diagnostics_received
@@ -507,7 +567,7 @@ impl FlycheckActor {
                             self.diagnostics_received = DiagnosticsReceived::YesAndClearedForAll;
                             self.send(FlycheckMessage::ClearDiagnostics {
                                 id: self.id,
-                                kind: ClearDiagnosticsKind::All,
+                                kind: ClearDiagnosticsKind::All(ClearScope::Workspace),
                             });
                         }
                         self.send(FlycheckMessage::AddDiagnostic {
@@ -548,7 +608,7 @@ impl FlycheckActor {
     /// return None.
     fn check_command(
         &self,
-        package: Option<&str>,
+        scope: &FlycheckScope,
         saved_file: Option<&AbsPath>,
         target: Option<Target>,
     ) -> Option<Command> {
@@ -564,9 +624,9 @@ impl FlycheckActor {
                 }
                 cmd.arg(command);
 
-                match package {
-                    Some(pkg) => cmd.arg("-p").arg(pkg),
-                    None => cmd.arg("--workspace"),
+                match scope {
+                    FlycheckScope::Workspace => cmd.arg("--workspace"),
+                    FlycheckScope::Package { package, .. } => cmd.arg("-p").arg(&package.repr),
                 };
 
                 if let Some(tgt) = target {
diff --git a/src/tools/rust-analyzer/crates/rust-analyzer/src/global_state.rs b/src/tools/rust-analyzer/crates/rust-analyzer/src/global_state.rs
index 89d6fb8edc2..ce6644f725c 100644
--- a/src/tools/rust-analyzer/crates/rust-analyzer/src/global_state.rs
+++ b/src/tools/rust-analyzer/crates/rust-analyzer/src/global_state.rs
@@ -9,6 +9,7 @@ use std::{
     time::{Duration, Instant},
 };
 
+use cargo_metadata::PackageId;
 use crossbeam_channel::{Receiver, Sender, unbounded};
 use hir::ChangeWithProcMacros;
 use ide::{Analysis, AnalysisHost, Cancellable, FileId, SourceRootId};
@@ -784,6 +785,7 @@ impl GlobalStateSnapshot {
                         cargo_toml: package_data.manifest.clone(),
                         crate_id,
                         package: cargo.package_flag(package_data),
+                        package_id: package_data.id.clone(),
                         target: target_data.name.clone(),
                         target_kind: target_data.kind,
                         required_features: target_data.required_features.clone(),
@@ -812,6 +814,27 @@ impl GlobalStateSnapshot {
         None
     }
 
+    pub(crate) fn all_workspace_dependencies_for_package(
+        &self,
+        package: &Arc<PackageId>,
+    ) -> Option<FxHashSet<Arc<PackageId>>> {
+        for workspace in self.workspaces.iter() {
+            match &workspace.kind {
+                ProjectWorkspaceKind::Cargo { cargo, .. }
+                | ProjectWorkspaceKind::DetachedFile { cargo: Some((cargo, _, _)), .. } => {
+                    let package = cargo.packages().find(|p| cargo[*p].id == *package)?;
+
+                    return cargo[package]
+                        .all_member_deps
+                        .as_ref()
+                        .map(|deps| deps.iter().map(|dep| cargo[*dep].id.clone()).collect());
+                }
+                _ => {}
+            }
+        }
+        None
+    }
+
     pub(crate) fn file_exists(&self, file_id: FileId) -> bool {
         self.vfs.read().0.exists(file_id)
     }
diff --git a/src/tools/rust-analyzer/crates/rust-analyzer/src/handlers/notification.rs b/src/tools/rust-analyzer/crates/rust-analyzer/src/handlers/notification.rs
index 68c91a65394..87be09dcbd2 100644
--- a/src/tools/rust-analyzer/crates/rust-analyzer/src/handlers/notification.rs
+++ b/src/tools/rust-analyzer/crates/rust-analyzer/src/handlers/notification.rs
@@ -331,7 +331,7 @@ fn run_flycheck(state: &mut GlobalState, vfs_path: VfsPath) -> bool {
                         let target = TargetSpec::for_file(&world, file_id)?.and_then(|it| {
                             let tgt_kind = it.target_kind();
                             let (tgt_name, root, package) = match it {
-                                TargetSpec::Cargo(c) => (c.target, c.workspace_root, c.package),
+                                TargetSpec::Cargo(c) => (c.target, c.workspace_root, c.package_id),
                                 _ => return None,
                             };
 
@@ -368,7 +368,13 @@ fn run_flycheck(state: &mut GlobalState, vfs_path: VfsPath) -> bool {
                                         _ => false,
                                     });
                                 if let Some(idx) = package_workspace_idx {
-                                    world.flycheck[idx].restart_for_package(package, target);
+                                    let workspace_deps =
+                                        world.all_workspace_dependencies_for_package(&package);
+                                    world.flycheck[idx].restart_for_package(
+                                        package,
+                                        target,
+                                        workspace_deps,
+                                    );
                                 }
                             }
                         }
diff --git a/src/tools/rust-analyzer/crates/rust-analyzer/src/main_loop.rs b/src/tools/rust-analyzer/crates/rust-analyzer/src/main_loop.rs
index c6762f31832..3e80e8b7bdf 100644
--- a/src/tools/rust-analyzer/crates/rust-analyzer/src/main_loop.rs
+++ b/src/tools/rust-analyzer/crates/rust-analyzer/src/main_loop.rs
@@ -20,7 +20,7 @@ use crate::{
     config::Config,
     diagnostics::{DiagnosticsGeneration, NativeDiagnosticsFetchKind, fetch_native_diagnostics},
     discover::{DiscoverArgument, DiscoverCommand, DiscoverProjectMessage},
-    flycheck::{self, ClearDiagnosticsKind, FlycheckMessage},
+    flycheck::{self, ClearDiagnosticsKind, ClearScope, FlycheckMessage},
     global_state::{
         FetchBuildDataResponse, FetchWorkspaceRequest, FetchWorkspaceResponse, GlobalState,
         file_id_to_url, url_to_file_id,
@@ -1042,17 +1042,22 @@ impl GlobalState {
                     };
                 }
             }
-            FlycheckMessage::ClearDiagnostics { id, kind: ClearDiagnosticsKind::All } => {
-                self.diagnostics.clear_check(id)
-            }
             FlycheckMessage::ClearDiagnostics {
                 id,
-                kind: ClearDiagnosticsKind::OlderThan(generation),
-            } => self.diagnostics.clear_check_older_than(id, generation),
+                kind: ClearDiagnosticsKind::All(ClearScope::Workspace),
+            } => self.diagnostics.clear_check(id),
             FlycheckMessage::ClearDiagnostics {
                 id,
-                kind: ClearDiagnosticsKind::Package(package_id),
+                kind: ClearDiagnosticsKind::All(ClearScope::Package(package_id)),
             } => self.diagnostics.clear_check_for_package(id, package_id),
+            FlycheckMessage::ClearDiagnostics {
+                id,
+                kind: ClearDiagnosticsKind::OlderThan(generation, ClearScope::Workspace),
+            } => self.diagnostics.clear_check_older_than(id, generation),
+            FlycheckMessage::ClearDiagnostics {
+                id,
+                kind: ClearDiagnosticsKind::OlderThan(generation, ClearScope::Package(package_id)),
+            } => self.diagnostics.clear_check_older_than_for_package(id, package_id, generation),
             FlycheckMessage::Progress { id, progress } => {
                 let (state, message) = match progress {
                     flycheck::Progress::DidStart => (Progress::Begin, None),
diff --git a/src/tools/rust-analyzer/crates/rust-analyzer/src/target_spec.rs b/src/tools/rust-analyzer/crates/rust-analyzer/src/target_spec.rs
index 7132e09146e..e532d155536 100644
--- a/src/tools/rust-analyzer/crates/rust-analyzer/src/target_spec.rs
+++ b/src/tools/rust-analyzer/crates/rust-analyzer/src/target_spec.rs
@@ -2,12 +2,14 @@
 
 use std::mem;
 
+use cargo_metadata::PackageId;
 use cfg::{CfgAtom, CfgExpr};
 use hir::sym;
 use ide::{Cancellable, Crate, FileId, RunnableKind, TestId};
 use project_model::project_json::Runnable;
 use project_model::{CargoFeatures, ManifestPath, TargetKind};
 use rustc_hash::FxHashSet;
+use triomphe::Arc;
 use vfs::AbsPathBuf;
 
 use crate::global_state::GlobalStateSnapshot;
@@ -52,6 +54,7 @@ pub(crate) struct CargoTargetSpec {
     pub(crate) workspace_root: AbsPathBuf,
     pub(crate) cargo_toml: ManifestPath,
     pub(crate) package: String,
+    pub(crate) package_id: Arc<PackageId>,
     pub(crate) target: String,
     pub(crate) target_kind: TargetKind,
     pub(crate) crate_id: Crate,
diff --git a/src/tools/rust-analyzer/crates/stdx/src/lib.rs b/src/tools/rust-analyzer/crates/stdx/src/lib.rs
index 978c50d807b..5fa00741637 100644
--- a/src/tools/rust-analyzer/crates/stdx/src/lib.rs
+++ b/src/tools/rust-analyzer/crates/stdx/src/lib.rs
@@ -187,11 +187,19 @@ pub fn is_upper_snake_case(s: &str) -> bool {
 }
 
 pub fn replace(buf: &mut String, from: char, to: &str) {
-    if !buf.contains(from) {
+    let replace_count = buf.chars().filter(|&ch| ch == from).count();
+    if replace_count == 0 {
         return;
     }
-    // FIXME: do this in place.
-    *buf = buf.replace(from, to);
+    let from_len = from.len_utf8();
+    let additional = to.len().saturating_sub(from_len);
+    buf.reserve(additional * replace_count);
+
+    let mut end = buf.len();
+    while let Some(i) = buf[..end].rfind(from) {
+        buf.replace_range(i..i + from_len, to);
+        end = i;
+    }
 }
 
 #[must_use]
@@ -343,4 +351,34 @@ mod tests {
             "fn main() {\n    return 92;\n}\n"
         );
     }
+
+    #[test]
+    fn test_replace() {
+        #[track_caller]
+        fn test_replace(src: &str, from: char, to: &str, expected: &str) {
+            let mut s = src.to_owned();
+            replace(&mut s, from, to);
+            assert_eq!(s, expected, "from: {from:?}, to: {to:?}");
+        }
+
+        test_replace("", 'a', "b", "");
+        test_replace("", 'a', "😀", "");
+        test_replace("", '😀', "a", "");
+        test_replace("a", 'a', "b", "b");
+        test_replace("aa", 'a', "b", "bb");
+        test_replace("ada", 'a', "b", "bdb");
+        test_replace("a", 'a', "😀", "😀");
+        test_replace("😀", '😀', "a", "a");
+        test_replace("😀x", '😀', "a", "ax");
+        test_replace("y😀x", '😀', "a", "yax");
+        test_replace("a,b,c", ',', ".", "a.b.c");
+        test_replace("a,b,c", ',', "..", "a..b..c");
+        test_replace("a.b.c", '.', "..", "a..b..c");
+        test_replace("a.b.c", '.', "..", "a..b..c");
+        test_replace("a😀b😀c", '😀', ".", "a.b.c");
+        test_replace("a.b.c", '.', "😀", "a😀b😀c");
+        test_replace("a.b.c", '.', "😀😀", "a😀😀b😀😀c");
+        test_replace(".a.b.c.", '.', "()", "()a()b()c()");
+        test_replace(".a.b.c.", '.', "", "abc");
+    }
 }
diff --git a/src/tools/rust-analyzer/crates/syntax/src/syntax_error.rs b/src/tools/rust-analyzer/crates/syntax/src/syntax_error.rs
index dc6130bd641..1c902893abc 100644
--- a/src/tools/rust-analyzer/crates/syntax/src/syntax_error.rs
+++ b/src/tools/rust-analyzer/crates/syntax/src/syntax_error.rs
@@ -42,3 +42,5 @@ impl fmt::Display for SyntaxError {
         self.0.fmt(f)
     }
 }
+
+impl std::error::Error for SyntaxError {}
diff --git a/src/tools/rust-analyzer/docs/book/src/configuration_generated.md b/src/tools/rust-analyzer/docs/book/src/configuration_generated.md
index 50dacd88f40..e78f1b4ba35 100644
--- a/src/tools/rust-analyzer/docs/book/src/configuration_generated.md
+++ b/src/tools/rust-analyzer/docs/book/src/configuration_generated.md
@@ -1046,6 +1046,8 @@ Default: `25`
 
 Maximum length for inlay hints. Set to null to have an unlimited length.
 
+**Note:** This is mostly a hint, and we don't guarantee to strictly follow the limit.
+
 
 ## rust-analyzer.inlayHints.parameterHints.enable {#inlayHints.parameterHints.enable}
 
diff --git a/src/tools/rust-analyzer/editors/code/package-lock.json b/src/tools/rust-analyzer/editors/code/package-lock.json
index ad8708e00c5..e35a159cbc3 100644
--- a/src/tools/rust-analyzer/editors/code/package-lock.json
+++ b/src/tools/rust-analyzer/editors/code/package-lock.json
@@ -6405,9 +6405,9 @@
             }
         },
         "node_modules/tar-fs": {
-            "version": "2.1.3",
-            "resolved": "https://registry.npmjs.org/tar-fs/-/tar-fs-2.1.3.tgz",
-            "integrity": "sha512-090nwYJDmlhwFwEW3QQl+vaNnxsO2yVsd45eTKRBzSzu+hlb1w2K9inVq5b0ngXuLVqQ4ApvsUHHnu/zQNkWAg==",
+            "version": "2.1.4",
+            "resolved": "https://registry.npmjs.org/tar-fs/-/tar-fs-2.1.4.tgz",
+            "integrity": "sha512-mDAjwmZdh7LTT6pNleZ05Yt65HC3E+NiQzl672vQG38jIrehtJk/J3mNwIg+vShQPcLF/LV7CMnDW6vjj6sfYQ==",
             "dev": true,
             "license": "MIT",
             "optional": true,
diff --git a/src/tools/rust-analyzer/editors/code/package.json b/src/tools/rust-analyzer/editors/code/package.json
index 1d27a120535..745e0da4efe 100644
--- a/src/tools/rust-analyzer/editors/code/package.json
+++ b/src/tools/rust-analyzer/editors/code/package.json
@@ -2355,7 +2355,7 @@
                 "title": "Inlay Hints",
                 "properties": {
                     "rust-analyzer.inlayHints.maxLength": {
-                        "markdownDescription": "Maximum length for inlay hints. Set to null to have an unlimited length.",
+                        "markdownDescription": "Maximum length for inlay hints. Set to null to have an unlimited length.\n\n**Note:** This is mostly a hint, and we don't guarantee to strictly follow the limit.",
                         "default": 25,
                         "type": [
                             "null",
diff --git a/src/tools/rust-analyzer/rust-version b/src/tools/rust-analyzer/rust-version
index 02b217f7d80..1f90d4e5e49 100644
--- a/src/tools/rust-analyzer/rust-version
+++ b/src/tools/rust-analyzer/rust-version
@@ -1 +1 @@
-21a19c297d4f5a03501d92ca251bd7a17073c08a
+f957826bff7a68b267ce75b1ea56352aed0cca0a
diff --git a/tests/codegen-llvm/autodiff/abi_handling.rs b/tests/codegen-llvm/autodiff/abi_handling.rs
index 454ec698b91..5c8126898a8 100644
--- a/tests/codegen-llvm/autodiff/abi_handling.rs
+++ b/tests/codegen-llvm/autodiff/abi_handling.rs
@@ -1,7 +1,7 @@
 //@ revisions: debug release
 
-//@[debug] compile-flags: -Zautodiff=Enable -C opt-level=0 -Clto=fat
-//@[release] compile-flags: -Zautodiff=Enable -C opt-level=3 -Clto=fat
+//@[debug] compile-flags: -Zautodiff=Enable,NoTT -C opt-level=0 -Clto=fat
+//@[release] compile-flags: -Zautodiff=Enable,NoTT -C opt-level=3 -Clto=fat
 //@ no-prefer-dynamic
 //@ needs-enzyme
 
diff --git a/tests/codegen-llvm/autodiff/batched.rs b/tests/codegen-llvm/autodiff/batched.rs
index 306a6ed9d1f..dc82403212f 100644
--- a/tests/codegen-llvm/autodiff/batched.rs
+++ b/tests/codegen-llvm/autodiff/batched.rs
@@ -1,4 +1,4 @@
-//@ compile-flags: -Zautodiff=Enable -C opt-level=3  -Clto=fat
+//@ compile-flags: -Zautodiff=Enable,NoTT -C opt-level=3  -Clto=fat
 //@ no-prefer-dynamic
 //@ needs-enzyme
 //
diff --git a/tests/codegen-llvm/autodiff/scalar.rs b/tests/codegen-llvm/autodiff/scalar.rs
index 55b989f920d..53672a89230 100644
--- a/tests/codegen-llvm/autodiff/scalar.rs
+++ b/tests/codegen-llvm/autodiff/scalar.rs
@@ -1,4 +1,4 @@
-//@ compile-flags: -Zautodiff=Enable -C opt-level=3  -Clto=fat
+//@ compile-flags: -Zautodiff=Enable,NoTT -C opt-level=3  -Clto=fat
 //@ no-prefer-dynamic
 //@ needs-enzyme
 #![feature(autodiff)]
diff --git a/tests/codegen-llvm/autodiff/sret.rs b/tests/codegen-llvm/autodiff/sret.rs
index dbc253ce894..498cd3fea01 100644
--- a/tests/codegen-llvm/autodiff/sret.rs
+++ b/tests/codegen-llvm/autodiff/sret.rs
@@ -1,4 +1,4 @@
-//@ compile-flags: -Zautodiff=Enable -C opt-level=3  -Clto=fat
+//@ compile-flags: -Zautodiff=Enable,NoTT -C opt-level=3  -Clto=fat
 //@ no-prefer-dynamic
 //@ needs-enzyme
 
diff --git a/tests/codegen-llvm/autodiff/void_ret.rs b/tests/codegen-llvm/autodiff/void_ret.rs
new file mode 100644
index 00000000000..98c6b98eef4
--- /dev/null
+++ b/tests/codegen-llvm/autodiff/void_ret.rs
@@ -0,0 +1,41 @@
+//@ compile-flags: -Zautodiff=Enable,NoTT,NoPostopt -C no-prepopulate-passes -C opt-level=3  -Clto=fat
+//@ no-prefer-dynamic
+//@ needs-enzyme
+
+#![feature(autodiff)]
+use std::autodiff::*;
+
+// Usually we would store the return value of the differentiated function.
+// However, if the return type is void or an empty struct,
+// we don't need to store anything. Verify this, since it caused a bug.
+
+// CHECK:; void_ret::main
+// CHECK-NEXT:    ; Function Attrs:
+// CHECK-NEXT:    define internal
+// CHECK-NOT: store {} undef, ptr undef
+// CHECK: ret void
+
+#[autodiff_reverse(bar, Duplicated, Duplicated)]
+pub fn foo(r: &[f64; 10], res: &mut f64) {
+    let mut output = [0.0; 10];
+    output[0] = r[0];
+    output[1] = r[1] * r[2];
+    output[2] = r[4] * r[5];
+    output[3] = r[2] * r[6];
+    output[4] = r[1] * r[7];
+    output[5] = r[2] * r[8];
+    output[6] = r[1] * r[9];
+    output[7] = r[5] * r[6];
+    output[8] = r[5] * r[7];
+    output[9] = r[4] * r[8];
+    *res = output.iter().sum();
+}
+fn main() {
+    let inputs = Box::new([3.1; 10]);
+    let mut d_inputs = Box::new([0.0; 10]);
+    let mut res = Box::new(0.0);
+    let mut d_res = Box::new(1.0);
+
+    bar(&inputs, &mut d_inputs, &mut res, &mut d_res);
+    dbg!(&d_inputs);
+}
diff --git a/tests/crashes/120016.rs b/tests/crashes/120016.rs
index 7eda330e7ad..12f54dbc3d9 100644
--- a/tests/crashes/120016.rs
+++ b/tests/crashes/120016.rs
@@ -1,19 +1,19 @@
 //@ known-bug: #120016
-//@ compile-flags: -Zcrate-attr=feature(const_async_blocks)
+//@ compile-flags: -Zvalidate-mir
 //@ edition: 2021
 
-#![feature(type_alias_impl_trait, const_async_blocks)]
+#![feature(type_alias_impl_trait)]
 
 struct Bug {
     V1: [(); {
-        type F = impl std::future::Future<Output = impl Sized>;
+        type F = impl Sized;
         #[define_opaque(F)]
         fn concrete_use() -> F {
-            //~^ ERROR to be a future that resolves to `u8`, but it resolves to `()`
-            async {}
+            //~^ ERROR
+            1i32
         }
-        let f: F = async { 1 };
-        //~^ ERROR `async` blocks are not allowed in constants
+        let f: F = 0u32;
+
         1
     }],
 }
diff --git a/tests/ui-fulldeps/mod_dir_path_canonicalized.rs b/tests/ui-fulldeps/mod_dir_path_canonicalized.rs
index df5f29e35fe..86f2d5f5954 100644
--- a/tests/ui-fulldeps/mod_dir_path_canonicalized.rs
+++ b/tests/ui-fulldeps/mod_dir_path_canonicalized.rs
@@ -2,7 +2,6 @@
 // Testing that a librustc_ast can parse modules with canonicalized base path
 //@ ignore-cross-compile
 //@ ignore-remote
-// no-remap-src-base: Reading `file!()` (expectedly) fails when enabled.
 
 #![feature(rustc_private)]
 
diff --git a/tests/ui/associated-type-bounds/duplicate-bound-err.rs b/tests/ui/associated-type-bounds/duplicate-bound-err.rs
new file mode 100644
index 00000000000..01cc05f2545
--- /dev/null
+++ b/tests/ui/associated-type-bounds/duplicate-bound-err.rs
@@ -0,0 +1,114 @@
+//@ edition: 2024
+
+#![feature(associated_const_equality, type_alias_impl_trait, return_type_notation)]
+#![allow(refining_impl_trait_internal)]
+
+use std::iter;
+
+fn rpit1() -> impl Iterator<Item: Copy, Item: Send> {
+    iter::empty()
+    //~^ ERROR type annotations needed
+}
+fn rpit2() -> impl Iterator<Item: Copy, Item: Copy> {
+    iter::empty()
+    //~^ ERROR type annotations needed
+}
+fn rpit3() -> impl Iterator<Item: 'static, Item: 'static> {
+    iter::empty()
+    //~^ ERROR type annotations needed
+}
+
+type Tait1<T: Iterator<Item: Copy, Item: Send>> = impl Copy;
+//~^ ERROR unconstrained opaque type
+type Tait2<T: Iterator<Item: Copy, Item: Copy>> = impl Copy;
+//~^ ERROR unconstrained opaque type
+type Tait3<T: Iterator<Item: 'static, Item: 'static>> = impl Copy;
+//~^ ERROR unconstrained opaque type
+
+type Tait4 = impl Iterator<Item: Copy, Item: Send>;
+//~^ ERROR unconstrained opaque type
+type Tait5 = impl Iterator<Item: Copy, Item: Copy>;
+//~^ ERROR unconstrained opaque type
+type Tait6 = impl Iterator<Item: 'static, Item: 'static>;
+//~^ ERROR unconstrained opaque type
+
+fn mismatch() -> impl Iterator<Item: Copy, Item: Send> {
+    //~^ ERROR [E0277]
+    iter::empty::<*const ()>()
+}
+
+fn mismatch_2() -> impl Iterator<Item: Copy, Item: Send> {
+    //~^ ERROR [E0277]
+    iter::empty::<String>()
+}
+
+trait Trait {
+    type Gat<T>;
+
+    const ASSOC: i32;
+
+    fn foo() -> impl Sized;
+}
+
+impl Trait for () {
+    type Gat<T> = ();
+
+    const ASSOC: i32 = 3;
+
+    fn foo() {}
+}
+
+impl Trait for u32 {
+    type Gat<T> = ();
+
+    const ASSOC: i32 = 4;
+
+    fn foo() -> u32 {
+        42
+    }
+}
+
+fn uncallable(_: impl Iterator<Item = i32, Item = u32>) {}
+
+fn uncallable_const(_: impl Trait<ASSOC = 3, ASSOC = 4>) {}
+
+fn uncallable_rtn(_: impl Trait<foo(..): Trait<ASSOC = 3>, foo(..): Trait<ASSOC = 4>>) {}
+
+type MustFail = dyn Iterator<Item = i32, Item = u32>;
+//~^ ERROR [E0719]
+//~| ERROR conflicting associated type bounds
+
+trait Trait2 {
+    const ASSOC: u32;
+}
+
+type MustFail2 = dyn Trait2<ASSOC = 3u32, ASSOC = 4u32>;
+//~^ ERROR [E0719]
+//~| ERROR conflicting associated type bounds
+
+type MustFail3 = dyn Iterator<Item = i32, Item = i32>;
+//~^ ERROR [E0719]
+
+type MustFail4 = dyn Trait2<ASSOC = 3u32, ASSOC = 3u32>;
+//~^ ERROR [E0719]
+
+trait Trait3 {
+    fn foo() -> impl Iterator<Item = i32, Item = u32>;
+}
+
+impl Trait3 for () {
+    fn foo() -> impl Iterator<Item = i32, Item = u32> {
+        //~^ ERROR[E0271]
+        //~| ERROR[E0271]
+        [2u32].into_iter()
+    }
+}
+
+fn main() {
+    uncallable(iter::empty::<u32>()); //~ ERROR [E0271]
+    uncallable(iter::empty::<i32>()); //~ ERROR [E0271]
+    uncallable_const(()); //~ ERROR [E0271]
+    uncallable_const(4u32); //~ ERROR [E0271]
+    uncallable_rtn(()); //~ ERROR [E0271]
+    uncallable_rtn(17u32); //~ ERROR [E0271]
+}
diff --git a/tests/ui/associated-type-bounds/duplicate-bound-err.stderr b/tests/ui/associated-type-bounds/duplicate-bound-err.stderr
new file mode 100644
index 00000000000..1737d0dc5a3
--- /dev/null
+++ b/tests/ui/associated-type-bounds/duplicate-bound-err.stderr
@@ -0,0 +1,268 @@
+error[E0282]: type annotations needed
+  --> $DIR/duplicate-bound-err.rs:9:5
+   |
+LL |     iter::empty()
+   |     ^^^^^^^^^^^ cannot infer type of the type parameter `T` declared on the function `empty`
+   |
+help: consider specifying the generic argument
+   |
+LL |     iter::empty::<T>()
+   |                +++++
+
+error[E0282]: type annotations needed
+  --> $DIR/duplicate-bound-err.rs:13:5
+   |
+LL |     iter::empty()
+   |     ^^^^^^^^^^^ cannot infer type of the type parameter `T` declared on the function `empty`
+   |
+help: consider specifying the generic argument
+   |
+LL |     iter::empty::<T>()
+   |                +++++
+
+error[E0282]: type annotations needed
+  --> $DIR/duplicate-bound-err.rs:17:5
+   |
+LL |     iter::empty()
+   |     ^^^^^^^^^^^ cannot infer type of the type parameter `T` declared on the function `empty`
+   |
+help: consider specifying the generic argument
+   |
+LL |     iter::empty::<T>()
+   |                +++++
+
+error: unconstrained opaque type
+  --> $DIR/duplicate-bound-err.rs:21:51
+   |
+LL | type Tait1<T: Iterator<Item: Copy, Item: Send>> = impl Copy;
+   |                                                   ^^^^^^^^^
+   |
+   = note: `Tait1` must be used in combination with a concrete type within the same crate
+
+error: unconstrained opaque type
+  --> $DIR/duplicate-bound-err.rs:23:51
+   |
+LL | type Tait2<T: Iterator<Item: Copy, Item: Copy>> = impl Copy;
+   |                                                   ^^^^^^^^^
+   |
+   = note: `Tait2` must be used in combination with a concrete type within the same crate
+
+error: unconstrained opaque type
+  --> $DIR/duplicate-bound-err.rs:25:57
+   |
+LL | type Tait3<T: Iterator<Item: 'static, Item: 'static>> = impl Copy;
+   |                                                         ^^^^^^^^^
+   |
+   = note: `Tait3` must be used in combination with a concrete type within the same crate
+
+error: unconstrained opaque type
+  --> $DIR/duplicate-bound-err.rs:28:14
+   |
+LL | type Tait4 = impl Iterator<Item: Copy, Item: Send>;
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `Tait4` must be used in combination with a concrete type within the same crate
+
+error: unconstrained opaque type
+  --> $DIR/duplicate-bound-err.rs:30:14
+   |
+LL | type Tait5 = impl Iterator<Item: Copy, Item: Copy>;
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `Tait5` must be used in combination with a concrete type within the same crate
+
+error: unconstrained opaque type
+  --> $DIR/duplicate-bound-err.rs:32:14
+   |
+LL | type Tait6 = impl Iterator<Item: 'static, Item: 'static>;
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `Tait6` must be used in combination with a concrete type within the same crate
+
+error[E0277]: `*const ()` cannot be sent between threads safely
+  --> $DIR/duplicate-bound-err.rs:35:18
+   |
+LL | fn mismatch() -> impl Iterator<Item: Copy, Item: Send> {
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `*const ()` cannot be sent between threads safely
+LL |
+LL |     iter::empty::<*const ()>()
+   |     -------------------------- return type was inferred to be `std::iter::Empty<*const ()>` here
+   |
+   = help: the trait `Send` is not implemented for `*const ()`
+
+error[E0277]: the trait bound `String: Copy` is not satisfied
+  --> $DIR/duplicate-bound-err.rs:40:20
+   |
+LL | fn mismatch_2() -> impl Iterator<Item: Copy, Item: Send> {
+   |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `String`
+LL |
+LL |     iter::empty::<String>()
+   |     ----------------------- return type was inferred to be `std::iter::Empty<String>` here
+
+error[E0271]: expected `IntoIter<u32, 1>` to be an iterator that yields `i32`, but it yields `u32`
+  --> $DIR/duplicate-bound-err.rs:100:17
+   |
+LL |     fn foo() -> impl Iterator<Item = i32, Item = u32> {
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `u32`
+...
+LL |         [2u32].into_iter()
+   |         ------------------ return type was inferred to be `std::array::IntoIter<u32, 1>` here
+
+error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
+  --> $DIR/duplicate-bound-err.rs:77:42
+   |
+LL | type MustFail = dyn Iterator<Item = i32, Item = u32>;
+   |                              ----------  ^^^^^^^^^^ re-bound here
+   |                              |
+   |                              `Item` bound here first
+
+error: conflicting associated type bounds for `Item`
+  --> $DIR/duplicate-bound-err.rs:77:17
+   |
+LL | type MustFail = dyn Iterator<Item = i32, Item = u32>;
+   |                 ^^^^^^^^^^^^^----------^^----------^
+   |                              |           |
+   |                              |           `Item` is specified to be `u32` here
+   |                              `Item` is specified to be `i32` here
+
+error[E0719]: the value of the associated type `ASSOC` in trait `Trait2` is already specified
+  --> $DIR/duplicate-bound-err.rs:85:43
+   |
+LL | type MustFail2 = dyn Trait2<ASSOC = 3u32, ASSOC = 4u32>;
+   |                             ------------  ^^^^^^^^^^^^ re-bound here
+   |                             |
+   |                             `ASSOC` bound here first
+
+error: conflicting associated type bounds for `ASSOC`
+  --> $DIR/duplicate-bound-err.rs:85:18
+   |
+LL | type MustFail2 = dyn Trait2<ASSOC = 3u32, ASSOC = 4u32>;
+   |                  ^^^^^^^^^^^------------^^------------^
+   |                             |             |
+   |                             |             `ASSOC` is specified to be `4` here
+   |                             `ASSOC` is specified to be `3` here
+
+error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
+  --> $DIR/duplicate-bound-err.rs:89:43
+   |
+LL | type MustFail3 = dyn Iterator<Item = i32, Item = i32>;
+   |                               ----------  ^^^^^^^^^^ re-bound here
+   |                               |
+   |                               `Item` bound here first
+
+error[E0719]: the value of the associated type `ASSOC` in trait `Trait2` is already specified
+  --> $DIR/duplicate-bound-err.rs:92:43
+   |
+LL | type MustFail4 = dyn Trait2<ASSOC = 3u32, ASSOC = 3u32>;
+   |                             ------------  ^^^^^^^^^^^^ re-bound here
+   |                             |
+   |                             `ASSOC` bound here first
+
+error[E0271]: expected `impl Iterator<Item = u32>` to be an iterator that yields `i32`, but it yields `u32`
+  --> $DIR/duplicate-bound-err.rs:100:17
+   |
+LL |     fn foo() -> impl Iterator<Item = i32, Item = u32> {
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `u32`
+   |
+note: required by a bound in `Trait3::foo::{anon_assoc#0}`
+  --> $DIR/duplicate-bound-err.rs:96:31
+   |
+LL |     fn foo() -> impl Iterator<Item = i32, Item = u32>;
+   |                               ^^^^^^^^^^ required by this bound in `Trait3::foo::{anon_assoc#0}`
+
+error[E0271]: expected `Empty<u32>` to be an iterator that yields `i32`, but it yields `u32`
+  --> $DIR/duplicate-bound-err.rs:108:16
+   |
+LL |     uncallable(iter::empty::<u32>());
+   |     ---------- ^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `u32`
+   |     |
+   |     required by a bound introduced by this call
+   |
+note: required by a bound in `uncallable`
+  --> $DIR/duplicate-bound-err.rs:71:32
+   |
+LL | fn uncallable(_: impl Iterator<Item = i32, Item = u32>) {}
+   |                                ^^^^^^^^^^ required by this bound in `uncallable`
+
+error[E0271]: expected `Empty<i32>` to be an iterator that yields `u32`, but it yields `i32`
+  --> $DIR/duplicate-bound-err.rs:109:16
+   |
+LL |     uncallable(iter::empty::<i32>());
+   |     ---------- ^^^^^^^^^^^^^^^^^^^^ expected `u32`, found `i32`
+   |     |
+   |     required by a bound introduced by this call
+   |
+note: required by a bound in `uncallable`
+  --> $DIR/duplicate-bound-err.rs:71:44
+   |
+LL | fn uncallable(_: impl Iterator<Item = i32, Item = u32>) {}
+   |                                            ^^^^^^^^^^ required by this bound in `uncallable`
+
+error[E0271]: type mismatch resolving `<() as Trait>::ASSOC == 4`
+  --> $DIR/duplicate-bound-err.rs:110:22
+   |
+LL |     uncallable_const(());
+   |     ---------------- ^^ expected `4`, found `3`
+   |     |
+   |     required by a bound introduced by this call
+   |
+   = note: expected constant `4`
+              found constant `3`
+note: required by a bound in `uncallable_const`
+  --> $DIR/duplicate-bound-err.rs:73:46
+   |
+LL | fn uncallable_const(_: impl Trait<ASSOC = 3, ASSOC = 4>) {}
+   |                                              ^^^^^^^^^ required by this bound in `uncallable_const`
+
+error[E0271]: type mismatch resolving `<u32 as Trait>::ASSOC == 3`
+  --> $DIR/duplicate-bound-err.rs:111:22
+   |
+LL |     uncallable_const(4u32);
+   |     ---------------- ^^^^ expected `3`, found `4`
+   |     |
+   |     required by a bound introduced by this call
+   |
+   = note: expected constant `3`
+              found constant `4`
+note: required by a bound in `uncallable_const`
+  --> $DIR/duplicate-bound-err.rs:73:35
+   |
+LL | fn uncallable_const(_: impl Trait<ASSOC = 3, ASSOC = 4>) {}
+   |                                   ^^^^^^^^^ required by this bound in `uncallable_const`
+
+error[E0271]: type mismatch resolving `<() as Trait>::ASSOC == 4`
+  --> $DIR/duplicate-bound-err.rs:112:20
+   |
+LL |     uncallable_rtn(());
+   |     -------------- ^^ expected `4`, found `3`
+   |     |
+   |     required by a bound introduced by this call
+   |
+   = note: expected constant `4`
+              found constant `3`
+note: required by a bound in `uncallable_rtn`
+  --> $DIR/duplicate-bound-err.rs:75:75
+   |
+LL | fn uncallable_rtn(_: impl Trait<foo(..): Trait<ASSOC = 3>, foo(..): Trait<ASSOC = 4>>) {}
+   |                                                                           ^^^^^^^^^ required by this bound in `uncallable_rtn`
+
+error[E0271]: type mismatch resolving `<u32 as Trait>::ASSOC == 3`
+  --> $DIR/duplicate-bound-err.rs:113:20
+   |
+LL |     uncallable_rtn(17u32);
+   |     -------------- ^^^^^ expected `3`, found `4`
+   |     |
+   |     required by a bound introduced by this call
+   |
+   = note: expected constant `3`
+              found constant `4`
+note: required by a bound in `uncallable_rtn`
+  --> $DIR/duplicate-bound-err.rs:75:48
+   |
+LL | fn uncallable_rtn(_: impl Trait<foo(..): Trait<ASSOC = 3>, foo(..): Trait<ASSOC = 4>>) {}
+   |                                                ^^^^^^^^^ required by this bound in `uncallable_rtn`
+
+error: aborting due to 25 previous errors
+
+Some errors have detailed explanations: E0271, E0277, E0282, E0719.
+For more information about an error, try `rustc --explain E0271`.
diff --git a/tests/ui/associated-type-bounds/duplicate-bound.rs b/tests/ui/associated-type-bounds/duplicate-bound.rs
new file mode 100644
index 00000000000..696710d76f6
--- /dev/null
+++ b/tests/ui/associated-type-bounds/duplicate-bound.rs
@@ -0,0 +1,240 @@
+//@ edition: 2024
+//@ run-pass
+
+#![feature(associated_const_equality, return_type_notation)]
+#![allow(dead_code, refining_impl_trait_internal, type_alias_bounds)]
+
+use std::iter;
+use std::mem::ManuallyDrop;
+
+struct Si1<T: Iterator<Item: Copy, Item: Send>> {
+    f: T,
+}
+struct Si2<T: Iterator<Item: Copy, Item: Copy>> {
+    f: T,
+}
+struct Si3<T: Iterator<Item: 'static, Item: 'static>> {
+    f: T,
+}
+struct Sw1<T>
+where
+    T: Iterator<Item: Copy, Item: Send>,
+{
+    f: T,
+}
+struct Sw2<T>
+where
+    T: Iterator<Item: Copy, Item: Copy>,
+{
+    f: T,
+}
+struct Sw3<T>
+where
+    T: Iterator<Item: 'static, Item: 'static>,
+{
+    f: T,
+}
+
+enum Ei1<T: Iterator<Item: Copy, Item: Send>> {
+    V(T),
+}
+enum Ei2<T: Iterator<Item: Copy, Item: Copy>> {
+    V(T),
+}
+enum Ei3<T: Iterator<Item: 'static, Item: 'static>> {
+    V(T),
+}
+enum Ew1<T>
+where
+    T: Iterator<Item: Copy, Item: Send>,
+{
+    V(T),
+}
+enum Ew2<T>
+where
+    T: Iterator<Item: Copy, Item: Copy>,
+{
+    V(T),
+}
+enum Ew3<T>
+where
+    T: Iterator<Item: 'static, Item: 'static>,
+{
+    V(T),
+}
+
+union Ui1<T: Iterator<Item: Copy, Item: Send>> {
+    f: ManuallyDrop<T>,
+}
+union Ui2<T: Iterator<Item: Copy, Item: Copy>> {
+    f: ManuallyDrop<T>,
+}
+union Ui3<T: Iterator<Item: 'static, Item: 'static>> {
+    f: ManuallyDrop<T>,
+}
+union Uw1<T>
+where
+    T: Iterator<Item: Copy, Item: Send>,
+{
+    f: ManuallyDrop<T>,
+}
+union Uw2<T>
+where
+    T: Iterator<Item: Copy, Item: Copy>,
+{
+    f: ManuallyDrop<T>,
+}
+union Uw3<T>
+where
+    T: Iterator<Item: 'static, Item: 'static>,
+{
+    f: ManuallyDrop<T>,
+}
+
+fn fi1<T: Iterator<Item: Copy, Item: Send>>() {}
+fn fi2<T: Iterator<Item: Copy, Item: Copy>>() {}
+fn fi3<T: Iterator<Item: 'static, Item: 'static>>() {}
+fn fw1<T>()
+where
+    T: Iterator<Item: Copy, Item: Send>,
+{
+}
+fn fw2<T>()
+where
+    T: Iterator<Item: Copy, Item: Copy>,
+{
+}
+fn fw3<T>()
+where
+    T: Iterator<Item: 'static, Item: 'static>,
+{
+}
+
+fn rpit1() -> impl Iterator<Item: Copy, Item: Send> {
+    iter::empty::<u32>()
+}
+fn rpit2() -> impl Iterator<Item: Copy, Item: Copy> {
+    iter::empty::<u32>()
+}
+fn rpit3() -> impl Iterator<Item: 'static, Item: 'static> {
+    iter::empty::<u32>()
+}
+fn apit1(_: impl Iterator<Item: Copy, Item: Send>) {}
+fn apit2(_: impl Iterator<Item: Copy, Item: Copy>) {}
+fn apit3(_: impl Iterator<Item: 'static, Item: 'static>) {}
+
+type Tait1<T: Iterator<Item: Copy, Item: Send>> = T;
+type Tait2<T: Iterator<Item: Copy, Item: Copy>> = T;
+type Tait3<T: Iterator<Item: 'static, Item: 'static>> = T;
+type Taw1<T>
+where
+    T: Iterator<Item: Copy, Item: Send>,
+= T;
+type Taw2<T>
+where
+    T: Iterator<Item: Copy, Item: Copy>,
+= T;
+type Taw3<T>
+where
+    T: Iterator<Item: 'static, Item: 'static>,
+= T;
+
+trait Tri1<T: Iterator<Item: Copy, Item: Send>> {}
+trait Tri2<T: Iterator<Item: Copy, Item: Copy>> {}
+trait Tri3<T: Iterator<Item: 'static, Item: 'static>> {}
+trait Trs1: Iterator<Item: Copy, Item: Send> {}
+trait Trs2: Iterator<Item: Copy, Item: Copy> {}
+trait Trs3: Iterator<Item: 'static, Item: 'static> {}
+trait Trw1<T>
+where
+    T: Iterator<Item: Copy, Item: Send>,
+{
+}
+trait Trw2<T>
+where
+    T: Iterator<Item: Copy, Item: Copy>,
+{
+}
+trait Trw3<T>
+where
+    T: Iterator<Item: 'static, Item: 'static>,
+{
+}
+trait Trsw1
+where
+    Self: Iterator<Item: Copy, Item: Send>,
+{
+}
+trait Trsw2
+where
+    Self: Iterator<Item: Copy, Item: Copy>,
+{
+}
+trait Trsw3
+where
+    Self: Iterator<Item: 'static, Item: 'static>,
+{
+}
+trait Tra1 {
+    type A: Iterator<Item: Copy, Item: Send>;
+}
+trait Tra2 {
+    type A: Iterator<Item: Copy, Item: Copy>;
+}
+trait Tra3 {
+    type A: Iterator<Item: 'static, Item: 'static>;
+}
+
+trait Trait {
+    type Gat<T>;
+
+    const ASSOC: i32;
+
+    fn foo() -> impl Sized;
+}
+
+impl Trait for () {
+    type Gat<T> = ();
+
+    const ASSOC: i32 = 3;
+
+    fn foo() {}
+}
+
+trait Subtrait: Trait<Gat<u32> = u32, Gat<u64> = u64> {}
+
+fn f<T: Trait<Gat<i32> = (), Gat<i64> = ()>>() {
+    let _: T::Gat<i32> = ();
+    let _: T::Gat<i64> = ();
+}
+
+fn g<T: Trait<Gat<i32> = (), Gat<i64> = &'static str>>() {
+    let _: T::Gat<i32> = ();
+    let _: T::Gat<i64> = "";
+}
+
+fn uncallable(_: impl Iterator<Item = i32, Item = u32>) {}
+
+fn callable(_: impl Iterator<Item = i32, Item = i32>) {}
+
+fn uncallable_const(_: impl Trait<ASSOC = 3, ASSOC = 4>) {}
+
+fn callable_const(_: impl Trait<ASSOC = 3, ASSOC = 3>) {}
+
+fn uncallable_rtn(_: impl Trait<foo(..): Trait<ASSOC = 3>, foo(..): Trait<ASSOC = 4>>) {}
+
+fn callable_rtn(_: impl Trait<foo(..): Send, foo(..): Send, foo(..): Eq>) {}
+
+trait Trait2 {
+    const ASSOC: u32;
+}
+
+trait Trait3 {
+    fn foo() -> impl Iterator<Item = i32, Item = u32>;
+}
+
+fn main() {
+    callable(iter::empty::<i32>());
+    callable_const(());
+    callable_rtn(());
+}
diff --git a/tests/ui/associated-type-bounds/duplicate.rs b/tests/ui/associated-type-bounds/duplicate.rs
deleted file mode 100644
index e9d94787e98..00000000000
--- a/tests/ui/associated-type-bounds/duplicate.rs
+++ /dev/null
@@ -1,278 +0,0 @@
-#![feature(type_alias_impl_trait)]
-
-use std::iter;
-use std::mem::ManuallyDrop;
-
-struct SI1<T: Iterator<Item: Copy, Item: Send>> {
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    f: T,
-}
-struct SI2<T: Iterator<Item: Copy, Item: Copy>> {
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    f: T,
-}
-struct SI3<T: Iterator<Item: 'static, Item: 'static>> {
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    f: T,
-}
-struct SW1<T>
-where
-    T: Iterator<Item: Copy, Item: Send>,
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-{
-    f: T,
-}
-struct SW2<T>
-where
-    T: Iterator<Item: Copy, Item: Copy>,
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-{
-    f: T,
-}
-struct SW3<T>
-where
-    T: Iterator<Item: 'static, Item: 'static>,
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-{
-    f: T,
-}
-
-enum EI1<T: Iterator<Item: Copy, Item: Send>> {
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    V(T),
-}
-enum EI2<T: Iterator<Item: Copy, Item: Copy>> {
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    V(T),
-}
-enum EI3<T: Iterator<Item: 'static, Item: 'static>> {
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    V(T),
-}
-enum EW1<T>
-where
-    T: Iterator<Item: Copy, Item: Send>,
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-{
-    V(T),
-}
-enum EW2<T>
-where
-    T: Iterator<Item: Copy, Item: Copy>,
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-{
-    V(T),
-}
-enum EW3<T>
-where
-    T: Iterator<Item: 'static, Item: 'static>,
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-{
-    V(T),
-}
-
-union UI1<T: Iterator<Item: Copy, Item: Send>> {
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    f: ManuallyDrop<T>,
-}
-union UI2<T: Iterator<Item: Copy, Item: Copy>> {
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    f: ManuallyDrop<T>,
-}
-union UI3<T: Iterator<Item: 'static, Item: 'static>> {
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    f: ManuallyDrop<T>,
-}
-union UW1<T>
-where
-    T: Iterator<Item: Copy, Item: Send>,
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-{
-    f: ManuallyDrop<T>,
-}
-union UW2<T>
-where
-    T: Iterator<Item: Copy, Item: Copy>,
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-{
-    f: ManuallyDrop<T>,
-}
-union UW3<T>
-where
-    T: Iterator<Item: 'static, Item: 'static>,
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-{
-    f: ManuallyDrop<T>,
-}
-
-fn FI1<T: Iterator<Item: Copy, Item: Send>>() {}
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-fn FI2<T: Iterator<Item: Copy, Item: Copy>>() {}
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-fn FI3<T: Iterator<Item: 'static, Item: 'static>>() {}
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-fn FW1<T>()
-where
-    T: Iterator<Item: Copy, Item: Send>,
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-{
-}
-fn FW2<T>()
-where
-    T: Iterator<Item: Copy, Item: Copy>,
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-{
-}
-fn FW3<T>()
-where
-    T: Iterator<Item: 'static, Item: 'static>,
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-{
-}
-
-fn FRPIT1() -> impl Iterator<Item: Copy, Item: Send> {
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    //~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    iter::empty()
-    //~^ ERROR type annotations needed
-}
-fn FRPIT2() -> impl Iterator<Item: Copy, Item: Copy> {
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    //~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    iter::empty()
-    //~^ ERROR type annotations needed
-}
-fn FRPIT3() -> impl Iterator<Item: 'static, Item: 'static> {
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    //~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    iter::empty()
-    //~^ ERROR type annotations needed
-}
-fn FAPIT1(_: impl Iterator<Item: Copy, Item: Send>) {}
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-fn FAPIT2(_: impl Iterator<Item: Copy, Item: Copy>) {}
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-fn FAPIT3(_: impl Iterator<Item: 'static, Item: 'static>) {}
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-
-type TAI1<T: Iterator<Item: Copy, Item: Send>> = T;
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-type TAI2<T: Iterator<Item: Copy, Item: Copy>> = T;
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-type TAI3<T: Iterator<Item: 'static, Item: 'static>> = T;
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-type TAW1<T>
-where
-    T: Iterator<Item: Copy, Item: Send>,
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-= T;
-type TAW2<T>
-where
-    T: Iterator<Item: Copy, Item: Copy>,
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-= T;
-type TAW3<T>
-where
-    T: Iterator<Item: 'static, Item: 'static>,
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-= T;
-
-type ETAI1<T: Iterator<Item: Copy, Item: Send>> = impl Copy;
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-//~| ERROR unconstrained opaque type
-type ETAI2<T: Iterator<Item: Copy, Item: Copy>> = impl Copy;
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-//~| ERROR unconstrained opaque type
-type ETAI3<T: Iterator<Item: 'static, Item: 'static>> = impl Copy;
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-//~| ERROR unconstrained opaque type
-type ETAI4 = impl Iterator<Item: Copy, Item: Send>;
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-//~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-//~| ERROR unconstrained opaque type
-type ETAI5 = impl Iterator<Item: Copy, Item: Copy>;
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-//~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-//~| ERROR unconstrained opaque type
-type ETAI6 = impl Iterator<Item: 'static, Item: 'static>;
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-//~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-//~| ERROR unconstrained opaque type
-
-trait TRI1<T: Iterator<Item: Copy, Item: Send>> {}
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-trait TRI2<T: Iterator<Item: Copy, Item: Copy>> {}
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-trait TRI3<T: Iterator<Item: 'static, Item: 'static>> {}
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-trait TRS1: Iterator<Item: Copy, Item: Send> {}
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-//~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-//~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-trait TRS2: Iterator<Item: Copy, Item: Copy> {}
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-//~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-//~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-trait TRS3: Iterator<Item: 'static, Item: 'static> {}
-//~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-//~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-//~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-trait TRW1<T>
-where
-    T: Iterator<Item: Copy, Item: Send>,
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-{
-}
-trait TRW2<T>
-where
-    T: Iterator<Item: Copy, Item: Copy>,
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-{
-}
-trait TRW3<T>
-where
-    T: Iterator<Item: 'static, Item: 'static>,
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-{
-}
-trait TRSW1
-where
-    Self: Iterator<Item: Copy, Item: Send>,
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    //~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    //~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-{
-}
-trait TRSW2
-where
-    Self: Iterator<Item: Copy, Item: Copy>,
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    //~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    //~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-{
-}
-trait TRSW3
-where
-    Self: Iterator<Item: 'static, Item: 'static>,
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    //~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    //~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-{
-}
-trait TRA1 {
-    type A: Iterator<Item: Copy, Item: Send>;
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    //~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-}
-trait TRA2 {
-    type A: Iterator<Item: Copy, Item: Copy>;
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    //~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-}
-trait TRA3 {
-    type A: Iterator<Item: 'static, Item: 'static>;
-    //~^ ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-    //~| ERROR the value of the associated type `Item` in trait `Iterator` is already specified [E0719]
-}
-
-fn main() {}
diff --git a/tests/ui/associated-type-bounds/duplicate.stderr b/tests/ui/associated-type-bounds/duplicate.stderr
deleted file mode 100644
index 68fbb345f6f..00000000000
--- a/tests/ui/associated-type-bounds/duplicate.stderr
+++ /dev/null
@@ -1,751 +0,0 @@
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:6:36
-   |
-LL | struct SI1<T: Iterator<Item: Copy, Item: Send>> {
-   |                        ----------  ^^^^^^^^^^ re-bound here
-   |                        |
-   |                        `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:10:36
-   |
-LL | struct SI2<T: Iterator<Item: Copy, Item: Copy>> {
-   |                        ----------  ^^^^^^^^^^ re-bound here
-   |                        |
-   |                        `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:14:39
-   |
-LL | struct SI3<T: Iterator<Item: 'static, Item: 'static>> {
-   |                        -------------  ^^^^^^^^^^^^^ re-bound here
-   |                        |
-   |                        `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:20:29
-   |
-LL |     T: Iterator<Item: Copy, Item: Send>,
-   |                 ----------  ^^^^^^^^^^ re-bound here
-   |                 |
-   |                 `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:27:29
-   |
-LL |     T: Iterator<Item: Copy, Item: Copy>,
-   |                 ----------  ^^^^^^^^^^ re-bound here
-   |                 |
-   |                 `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:34:32
-   |
-LL |     T: Iterator<Item: 'static, Item: 'static>,
-   |                 -------------  ^^^^^^^^^^^^^ re-bound here
-   |                 |
-   |                 `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:40:34
-   |
-LL | enum EI1<T: Iterator<Item: Copy, Item: Send>> {
-   |                      ----------  ^^^^^^^^^^ re-bound here
-   |                      |
-   |                      `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:44:34
-   |
-LL | enum EI2<T: Iterator<Item: Copy, Item: Copy>> {
-   |                      ----------  ^^^^^^^^^^ re-bound here
-   |                      |
-   |                      `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:48:37
-   |
-LL | enum EI3<T: Iterator<Item: 'static, Item: 'static>> {
-   |                      -------------  ^^^^^^^^^^^^^ re-bound here
-   |                      |
-   |                      `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:54:29
-   |
-LL |     T: Iterator<Item: Copy, Item: Send>,
-   |                 ----------  ^^^^^^^^^^ re-bound here
-   |                 |
-   |                 `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:61:29
-   |
-LL |     T: Iterator<Item: Copy, Item: Copy>,
-   |                 ----------  ^^^^^^^^^^ re-bound here
-   |                 |
-   |                 `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:68:32
-   |
-LL |     T: Iterator<Item: 'static, Item: 'static>,
-   |                 -------------  ^^^^^^^^^^^^^ re-bound here
-   |                 |
-   |                 `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:74:35
-   |
-LL | union UI1<T: Iterator<Item: Copy, Item: Send>> {
-   |                       ----------  ^^^^^^^^^^ re-bound here
-   |                       |
-   |                       `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:78:35
-   |
-LL | union UI2<T: Iterator<Item: Copy, Item: Copy>> {
-   |                       ----------  ^^^^^^^^^^ re-bound here
-   |                       |
-   |                       `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:82:38
-   |
-LL | union UI3<T: Iterator<Item: 'static, Item: 'static>> {
-   |                       -------------  ^^^^^^^^^^^^^ re-bound here
-   |                       |
-   |                       `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:88:29
-   |
-LL |     T: Iterator<Item: Copy, Item: Send>,
-   |                 ----------  ^^^^^^^^^^ re-bound here
-   |                 |
-   |                 `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:95:29
-   |
-LL |     T: Iterator<Item: Copy, Item: Copy>,
-   |                 ----------  ^^^^^^^^^^ re-bound here
-   |                 |
-   |                 `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:102:32
-   |
-LL |     T: Iterator<Item: 'static, Item: 'static>,
-   |                 -------------  ^^^^^^^^^^^^^ re-bound here
-   |                 |
-   |                 `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:108:32
-   |
-LL | fn FI1<T: Iterator<Item: Copy, Item: Send>>() {}
-   |                    ----------  ^^^^^^^^^^ re-bound here
-   |                    |
-   |                    `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:110:32
-   |
-LL | fn FI2<T: Iterator<Item: Copy, Item: Copy>>() {}
-   |                    ----------  ^^^^^^^^^^ re-bound here
-   |                    |
-   |                    `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:112:35
-   |
-LL | fn FI3<T: Iterator<Item: 'static, Item: 'static>>() {}
-   |                    -------------  ^^^^^^^^^^^^^ re-bound here
-   |                    |
-   |                    `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:116:29
-   |
-LL |     T: Iterator<Item: Copy, Item: Send>,
-   |                 ----------  ^^^^^^^^^^ re-bound here
-   |                 |
-   |                 `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:122:29
-   |
-LL |     T: Iterator<Item: Copy, Item: Copy>,
-   |                 ----------  ^^^^^^^^^^ re-bound here
-   |                 |
-   |                 `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:128:32
-   |
-LL |     T: Iterator<Item: 'static, Item: 'static>,
-   |                 -------------  ^^^^^^^^^^^^^ re-bound here
-   |                 |
-   |                 `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:133:42
-   |
-LL | fn FRPIT1() -> impl Iterator<Item: Copy, Item: Send> {
-   |                              ----------  ^^^^^^^^^^ re-bound here
-   |                              |
-   |                              `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:139:42
-   |
-LL | fn FRPIT2() -> impl Iterator<Item: Copy, Item: Copy> {
-   |                              ----------  ^^^^^^^^^^ re-bound here
-   |                              |
-   |                              `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:145:45
-   |
-LL | fn FRPIT3() -> impl Iterator<Item: 'static, Item: 'static> {
-   |                              -------------  ^^^^^^^^^^^^^ re-bound here
-   |                              |
-   |                              `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:151:40
-   |
-LL | fn FAPIT1(_: impl Iterator<Item: Copy, Item: Send>) {}
-   |                            ----------  ^^^^^^^^^^ re-bound here
-   |                            |
-   |                            `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:153:40
-   |
-LL | fn FAPIT2(_: impl Iterator<Item: Copy, Item: Copy>) {}
-   |                            ----------  ^^^^^^^^^^ re-bound here
-   |                            |
-   |                            `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:155:43
-   |
-LL | fn FAPIT3(_: impl Iterator<Item: 'static, Item: 'static>) {}
-   |                            -------------  ^^^^^^^^^^^^^ re-bound here
-   |                            |
-   |                            `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:158:35
-   |
-LL | type TAI1<T: Iterator<Item: Copy, Item: Send>> = T;
-   |                       ----------  ^^^^^^^^^^ re-bound here
-   |                       |
-   |                       `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:160:35
-   |
-LL | type TAI2<T: Iterator<Item: Copy, Item: Copy>> = T;
-   |                       ----------  ^^^^^^^^^^ re-bound here
-   |                       |
-   |                       `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:162:38
-   |
-LL | type TAI3<T: Iterator<Item: 'static, Item: 'static>> = T;
-   |                       -------------  ^^^^^^^^^^^^^ re-bound here
-   |                       |
-   |                       `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:166:29
-   |
-LL |     T: Iterator<Item: Copy, Item: Send>,
-   |                 ----------  ^^^^^^^^^^ re-bound here
-   |                 |
-   |                 `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:171:29
-   |
-LL |     T: Iterator<Item: Copy, Item: Copy>,
-   |                 ----------  ^^^^^^^^^^ re-bound here
-   |                 |
-   |                 `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:176:32
-   |
-LL |     T: Iterator<Item: 'static, Item: 'static>,
-   |                 -------------  ^^^^^^^^^^^^^ re-bound here
-   |                 |
-   |                 `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:180:36
-   |
-LL | type ETAI1<T: Iterator<Item: Copy, Item: Send>> = impl Copy;
-   |                        ----------  ^^^^^^^^^^ re-bound here
-   |                        |
-   |                        `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:183:36
-   |
-LL | type ETAI2<T: Iterator<Item: Copy, Item: Copy>> = impl Copy;
-   |                        ----------  ^^^^^^^^^^ re-bound here
-   |                        |
-   |                        `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:186:39
-   |
-LL | type ETAI3<T: Iterator<Item: 'static, Item: 'static>> = impl Copy;
-   |                        -------------  ^^^^^^^^^^^^^ re-bound here
-   |                        |
-   |                        `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:202:36
-   |
-LL | trait TRI1<T: Iterator<Item: Copy, Item: Send>> {}
-   |                        ----------  ^^^^^^^^^^ re-bound here
-   |                        |
-   |                        `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:204:36
-   |
-LL | trait TRI2<T: Iterator<Item: Copy, Item: Copy>> {}
-   |                        ----------  ^^^^^^^^^^ re-bound here
-   |                        |
-   |                        `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:206:39
-   |
-LL | trait TRI3<T: Iterator<Item: 'static, Item: 'static>> {}
-   |                        -------------  ^^^^^^^^^^^^^ re-bound here
-   |                        |
-   |                        `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:208:34
-   |
-LL | trait TRS1: Iterator<Item: Copy, Item: Send> {}
-   |                      ----------  ^^^^^^^^^^ re-bound here
-   |                      |
-   |                      `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:208:34
-   |
-LL | trait TRS1: Iterator<Item: Copy, Item: Send> {}
-   |                      ----------  ^^^^^^^^^^ re-bound here
-   |                      |
-   |                      `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:208:34
-   |
-LL | trait TRS1: Iterator<Item: Copy, Item: Send> {}
-   |                      ----------  ^^^^^^^^^^ re-bound here
-   |                      |
-   |                      `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:212:34
-   |
-LL | trait TRS2: Iterator<Item: Copy, Item: Copy> {}
-   |                      ----------  ^^^^^^^^^^ re-bound here
-   |                      |
-   |                      `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:212:34
-   |
-LL | trait TRS2: Iterator<Item: Copy, Item: Copy> {}
-   |                      ----------  ^^^^^^^^^^ re-bound here
-   |                      |
-   |                      `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:212:34
-   |
-LL | trait TRS2: Iterator<Item: Copy, Item: Copy> {}
-   |                      ----------  ^^^^^^^^^^ re-bound here
-   |                      |
-   |                      `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:216:37
-   |
-LL | trait TRS3: Iterator<Item: 'static, Item: 'static> {}
-   |                      -------------  ^^^^^^^^^^^^^ re-bound here
-   |                      |
-   |                      `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:216:37
-   |
-LL | trait TRS3: Iterator<Item: 'static, Item: 'static> {}
-   |                      -------------  ^^^^^^^^^^^^^ re-bound here
-   |                      |
-   |                      `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:216:37
-   |
-LL | trait TRS3: Iterator<Item: 'static, Item: 'static> {}
-   |                      -------------  ^^^^^^^^^^^^^ re-bound here
-   |                      |
-   |                      `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:222:29
-   |
-LL |     T: Iterator<Item: Copy, Item: Send>,
-   |                 ----------  ^^^^^^^^^^ re-bound here
-   |                 |
-   |                 `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:228:29
-   |
-LL |     T: Iterator<Item: Copy, Item: Copy>,
-   |                 ----------  ^^^^^^^^^^ re-bound here
-   |                 |
-   |                 `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:234:32
-   |
-LL |     T: Iterator<Item: 'static, Item: 'static>,
-   |                 -------------  ^^^^^^^^^^^^^ re-bound here
-   |                 |
-   |                 `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:240:32
-   |
-LL |     Self: Iterator<Item: Copy, Item: Send>,
-   |                    ----------  ^^^^^^^^^^ re-bound here
-   |                    |
-   |                    `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:240:32
-   |
-LL |     Self: Iterator<Item: Copy, Item: Send>,
-   |                    ----------  ^^^^^^^^^^ re-bound here
-   |                    |
-   |                    `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:240:32
-   |
-LL |     Self: Iterator<Item: Copy, Item: Send>,
-   |                    ----------  ^^^^^^^^^^ re-bound here
-   |                    |
-   |                    `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:248:32
-   |
-LL |     Self: Iterator<Item: Copy, Item: Copy>,
-   |                    ----------  ^^^^^^^^^^ re-bound here
-   |                    |
-   |                    `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:248:32
-   |
-LL |     Self: Iterator<Item: Copy, Item: Copy>,
-   |                    ----------  ^^^^^^^^^^ re-bound here
-   |                    |
-   |                    `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:248:32
-   |
-LL |     Self: Iterator<Item: Copy, Item: Copy>,
-   |                    ----------  ^^^^^^^^^^ re-bound here
-   |                    |
-   |                    `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:256:35
-   |
-LL |     Self: Iterator<Item: 'static, Item: 'static>,
-   |                    -------------  ^^^^^^^^^^^^^ re-bound here
-   |                    |
-   |                    `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:256:35
-   |
-LL |     Self: Iterator<Item: 'static, Item: 'static>,
-   |                    -------------  ^^^^^^^^^^^^^ re-bound here
-   |                    |
-   |                    `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:256:35
-   |
-LL |     Self: Iterator<Item: 'static, Item: 'static>,
-   |                    -------------  ^^^^^^^^^^^^^ re-bound here
-   |                    |
-   |                    `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:263:34
-   |
-LL |     type A: Iterator<Item: Copy, Item: Send>;
-   |                      ----------  ^^^^^^^^^^ re-bound here
-   |                      |
-   |                      `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:263:34
-   |
-LL |     type A: Iterator<Item: Copy, Item: Send>;
-   |                      ----------  ^^^^^^^^^^ re-bound here
-   |                      |
-   |                      `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:268:34
-   |
-LL |     type A: Iterator<Item: Copy, Item: Copy>;
-   |                      ----------  ^^^^^^^^^^ re-bound here
-   |                      |
-   |                      `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:268:34
-   |
-LL |     type A: Iterator<Item: Copy, Item: Copy>;
-   |                      ----------  ^^^^^^^^^^ re-bound here
-   |                      |
-   |                      `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:273:37
-   |
-LL |     type A: Iterator<Item: 'static, Item: 'static>;
-   |                      -------------  ^^^^^^^^^^^^^ re-bound here
-   |                      |
-   |                      `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:273:37
-   |
-LL |     type A: Iterator<Item: 'static, Item: 'static>;
-   |                      -------------  ^^^^^^^^^^^^^ re-bound here
-   |                      |
-   |                      `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:133:42
-   |
-LL | fn FRPIT1() -> impl Iterator<Item: Copy, Item: Send> {
-   |                              ----------  ^^^^^^^^^^ re-bound here
-   |                              |
-   |                              `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0282]: type annotations needed
-  --> $DIR/duplicate.rs:136:5
-   |
-LL |     iter::empty()
-   |     ^^^^^^^^^^^ cannot infer type of the type parameter `T` declared on the function `empty`
-   |
-help: consider specifying the generic argument
-   |
-LL |     iter::empty::<T>()
-   |                +++++
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:139:42
-   |
-LL | fn FRPIT2() -> impl Iterator<Item: Copy, Item: Copy> {
-   |                              ----------  ^^^^^^^^^^ re-bound here
-   |                              |
-   |                              `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0282]: type annotations needed
-  --> $DIR/duplicate.rs:142:5
-   |
-LL |     iter::empty()
-   |     ^^^^^^^^^^^ cannot infer type of the type parameter `T` declared on the function `empty`
-   |
-help: consider specifying the generic argument
-   |
-LL |     iter::empty::<T>()
-   |                +++++
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:145:45
-   |
-LL | fn FRPIT3() -> impl Iterator<Item: 'static, Item: 'static> {
-   |                              -------------  ^^^^^^^^^^^^^ re-bound here
-   |                              |
-   |                              `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0282]: type annotations needed
-  --> $DIR/duplicate.rs:148:5
-   |
-LL |     iter::empty()
-   |     ^^^^^^^^^^^ cannot infer type of the type parameter `T` declared on the function `empty`
-   |
-help: consider specifying the generic argument
-   |
-LL |     iter::empty::<T>()
-   |                +++++
-
-error: unconstrained opaque type
-  --> $DIR/duplicate.rs:180:51
-   |
-LL | type ETAI1<T: Iterator<Item: Copy, Item: Send>> = impl Copy;
-   |                                                   ^^^^^^^^^
-   |
-   = note: `ETAI1` must be used in combination with a concrete type within the same crate
-
-error: unconstrained opaque type
-  --> $DIR/duplicate.rs:183:51
-   |
-LL | type ETAI2<T: Iterator<Item: Copy, Item: Copy>> = impl Copy;
-   |                                                   ^^^^^^^^^
-   |
-   = note: `ETAI2` must be used in combination with a concrete type within the same crate
-
-error: unconstrained opaque type
-  --> $DIR/duplicate.rs:186:57
-   |
-LL | type ETAI3<T: Iterator<Item: 'static, Item: 'static>> = impl Copy;
-   |                                                         ^^^^^^^^^
-   |
-   = note: `ETAI3` must be used in combination with a concrete type within the same crate
-
-error: unconstrained opaque type
-  --> $DIR/duplicate.rs:189:14
-   |
-LL | type ETAI4 = impl Iterator<Item: Copy, Item: Send>;
-   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `ETAI4` must be used in combination with a concrete type within the same crate
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:189:40
-   |
-LL | type ETAI4 = impl Iterator<Item: Copy, Item: Send>;
-   |                            ----------  ^^^^^^^^^^ re-bound here
-   |                            |
-   |                            `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:189:40
-   |
-LL | type ETAI4 = impl Iterator<Item: Copy, Item: Send>;
-   |                            ----------  ^^^^^^^^^^ re-bound here
-   |                            |
-   |                            `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error: unconstrained opaque type
-  --> $DIR/duplicate.rs:193:14
-   |
-LL | type ETAI5 = impl Iterator<Item: Copy, Item: Copy>;
-   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `ETAI5` must be used in combination with a concrete type within the same crate
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:193:40
-   |
-LL | type ETAI5 = impl Iterator<Item: Copy, Item: Copy>;
-   |                            ----------  ^^^^^^^^^^ re-bound here
-   |                            |
-   |                            `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:193:40
-   |
-LL | type ETAI5 = impl Iterator<Item: Copy, Item: Copy>;
-   |                            ----------  ^^^^^^^^^^ re-bound here
-   |                            |
-   |                            `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error: unconstrained opaque type
-  --> $DIR/duplicate.rs:197:14
-   |
-LL | type ETAI6 = impl Iterator<Item: 'static, Item: 'static>;
-   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `ETAI6` must be used in combination with a concrete type within the same crate
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:197:43
-   |
-LL | type ETAI6 = impl Iterator<Item: 'static, Item: 'static>;
-   |                            -------------  ^^^^^^^^^^^^^ re-bound here
-   |                            |
-   |                            `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/duplicate.rs:197:43
-   |
-LL | type ETAI6 = impl Iterator<Item: 'static, Item: 'static>;
-   |                            -------------  ^^^^^^^^^^^^^ re-bound here
-   |                            |
-   |                            `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error: aborting due to 87 previous errors
-
-Some errors have detailed explanations: E0282, E0719.
-For more information about an error, try `rustc --explain E0282`.
diff --git a/tests/ui/associated-types/associated-types-overridden-binding-2.stderr b/tests/ui/associated-types/associated-types-overridden-binding-2.stderr
index 71a4a2610aa..e96a2446b6c 100644
--- a/tests/ui/associated-types/associated-types-overridden-binding-2.stderr
+++ b/tests/ui/associated-types/associated-types-overridden-binding-2.stderr
@@ -1,4 +1,4 @@
-error: conflicting associated type bounds for `Item` when expanding trait alias
+error: conflicting associated type bounds for `Item`
   --> $DIR/associated-types-overridden-binding-2.rs:6:13
    |
 LL | trait I32Iterator = Iterator<Item = i32>;
diff --git a/tests/ui/associated-types/associated-types-overridden-binding.stderr b/tests/ui/associated-types/associated-types-overridden-binding.stderr
index 3b20015dfca..08ab9b63ee9 100644
--- a/tests/ui/associated-types/associated-types-overridden-binding.stderr
+++ b/tests/ui/associated-types/associated-types-overridden-binding.stderr
@@ -22,7 +22,7 @@ note: required by a bound in `I32Iterator`
 LL | trait I32Iterator = Iterator<Item = i32>;
    |                              ^^^^^^^^^^ required by this bound in `I32Iterator`
 
-error: conflicting associated type bounds for `Item` when expanding trait alias
+error: conflicting associated type bounds for `Item`
   --> $DIR/associated-types-overridden-binding.rs:10:13
    |
 LL | trait I32Iterator = Iterator<Item = i32>;
diff --git a/tests/ui/attributes/unsafe/double-unsafe-attributes.rs b/tests/ui/attributes/unsafe/double-unsafe-attributes.rs
index 894d1327da7..c0181d96053 100644
--- a/tests/ui/attributes/unsafe/double-unsafe-attributes.rs
+++ b/tests/ui/attributes/unsafe/double-unsafe-attributes.rs
@@ -1,7 +1,7 @@
 #[unsafe(unsafe(no_mangle))]
 //~^ ERROR expected identifier, found keyword `unsafe`
 //~| ERROR cannot find attribute `r#unsafe` in this scope
-//~| ERROR `r#unsafe` is not an unsafe attribute
+//~| ERROR unnecessary `unsafe`
 fn a() {}
 
 fn main() {}
diff --git a/tests/ui/attributes/unsafe/double-unsafe-attributes.stderr b/tests/ui/attributes/unsafe/double-unsafe-attributes.stderr
index 0825cf79408..846800daa54 100644
--- a/tests/ui/attributes/unsafe/double-unsafe-attributes.stderr
+++ b/tests/ui/attributes/unsafe/double-unsafe-attributes.stderr
@@ -9,13 +9,11 @@ help: escape `unsafe` to use it as an identifier
 LL | #[unsafe(r#unsafe(no_mangle))]
    |          ++
 
-error: `r#unsafe` is not an unsafe attribute
+error: unnecessary `unsafe` on safe attribute
   --> $DIR/double-unsafe-attributes.rs:1:3
    |
 LL | #[unsafe(unsafe(no_mangle))]
-   |   ^^^^^^ this is not an unsafe attribute
-   |
-   = note: extraneous unsafe is not allowed in attributes
+   |   ^^^^^^
 
 error: cannot find attribute `r#unsafe` in this scope
   --> $DIR/double-unsafe-attributes.rs:1:10
diff --git a/tests/ui/attributes/unsafe/unsafe-safe-attribute_diagnostic.rs b/tests/ui/attributes/unsafe/unsafe-safe-attribute_diagnostic.rs
index 0f241cc439f..d9054248a29 100644
--- a/tests/ui/attributes/unsafe/unsafe-safe-attribute_diagnostic.rs
+++ b/tests/ui/attributes/unsafe/unsafe-safe-attribute_diagnostic.rs
@@ -1,4 +1,4 @@
-#[unsafe(diagnostic::on_unimplemented( //~ ERROR: is not an unsafe attribute
+#[unsafe(diagnostic::on_unimplemented( //~ ERROR: unnecessary `unsafe`
     message = "testing",
 ))]
 trait Foo {}
diff --git a/tests/ui/attributes/unsafe/unsafe-safe-attribute_diagnostic.stderr b/tests/ui/attributes/unsafe/unsafe-safe-attribute_diagnostic.stderr
index 3bc291db5ac..a7662f5ee6c 100644
--- a/tests/ui/attributes/unsafe/unsafe-safe-attribute_diagnostic.stderr
+++ b/tests/ui/attributes/unsafe/unsafe-safe-attribute_diagnostic.stderr
@@ -1,10 +1,8 @@
-error: `diagnostic::on_unimplemented` is not an unsafe attribute
+error: unnecessary `unsafe` on safe attribute
   --> $DIR/unsafe-safe-attribute_diagnostic.rs:1:3
    |
 LL | #[unsafe(diagnostic::on_unimplemented(
-   |   ^^^^^^ this is not an unsafe attribute
-   |
-   = note: extraneous unsafe is not allowed in attributes
+   |   ^^^^^^
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/closures/impl-closure-147146.rs b/tests/ui/closures/impl-closure-147146.rs
new file mode 100644
index 00000000000..b709e577354
--- /dev/null
+++ b/tests/ui/closures/impl-closure-147146.rs
@@ -0,0 +1,7 @@
+impl typeof(|| {}) {}
+//~^ ERROR `typeof` is a reserved keyword but unimplemented
+
+unsafe impl Send for typeof(|| {}) {}
+//~^ ERROR `typeof` is a reserved keyword but unimplemented
+
+fn main() {}
diff --git a/tests/ui/closures/impl-closure-147146.stderr b/tests/ui/closures/impl-closure-147146.stderr
new file mode 100644
index 00000000000..6da16b5d450
--- /dev/null
+++ b/tests/ui/closures/impl-closure-147146.stderr
@@ -0,0 +1,15 @@
+error[E0516]: `typeof` is a reserved keyword but unimplemented
+  --> $DIR/impl-closure-147146.rs:1:6
+   |
+LL | impl typeof(|| {}) {}
+   |      ^^^^^^^^^^^^^ reserved keyword
+
+error[E0516]: `typeof` is a reserved keyword but unimplemented
+  --> $DIR/impl-closure-147146.rs:4:22
+   |
+LL | unsafe impl Send for typeof(|| {}) {}
+   |                      ^^^^^^^^^^^^^ reserved keyword
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0516`.
diff --git a/tests/ui/cmse-nonsecure/cmse-nonsecure-call/undeclared-lifetime.rs b/tests/ui/cmse-nonsecure/cmse-nonsecure-call/undeclared-lifetime.rs
index 5fa5b74c0c0..0a0dca804ef 100644
--- a/tests/ui/cmse-nonsecure/cmse-nonsecure-call/undeclared-lifetime.rs
+++ b/tests/ui/cmse-nonsecure/cmse-nonsecure-call/undeclared-lifetime.rs
@@ -1,5 +1,6 @@
 //@ add-core-stubs
-//@ compile-flags: --target thumbv8m.main-none-eabi --crate-type lib -Cincremental=true
+//@ compile-flags: --target thumbv8m.main-none-eabi --crate-type lib
+//@ incremental (required to trigger the bug)
 //@ needs-llvm-components: arm
 #![feature(abi_cmse_nonsecure_call, no_core)]
 #![no_core]
@@ -8,7 +9,7 @@ extern crate minicore;
 use minicore::*;
 
 // A regression test for https://github.com/rust-lang/rust/issues/131639.
-// NOTE: -Cincremental=true was required for triggering the bug.
+// NOTE: `-Cincremental` was required for triggering the bug.
 
 fn foo() {
     id::<extern "cmse-nonsecure-call" fn(&'a ())>(PhantomData);
diff --git a/tests/ui/cmse-nonsecure/cmse-nonsecure-call/undeclared-lifetime.stderr b/tests/ui/cmse-nonsecure/cmse-nonsecure-call/undeclared-lifetime.stderr
index 4aca17e7354..7300bdb72cd 100644
--- a/tests/ui/cmse-nonsecure/cmse-nonsecure-call/undeclared-lifetime.stderr
+++ b/tests/ui/cmse-nonsecure/cmse-nonsecure-call/undeclared-lifetime.stderr
@@ -1,5 +1,5 @@
 error[E0261]: use of undeclared lifetime name `'a`
-  --> $DIR/undeclared-lifetime.rs:14:43
+  --> $DIR/undeclared-lifetime.rs:15:43
    |
 LL |     id::<extern "cmse-nonsecure-call" fn(&'a ())>(PhantomData);
    |                                           ^^ undeclared lifetime
diff --git a/tests/ui/compiletest-self-test/compile-flags-incremental.rs b/tests/ui/compiletest-self-test/compile-flags-incremental.rs
new file mode 100644
index 00000000000..62a1ad84d8f
--- /dev/null
+++ b/tests/ui/compiletest-self-test/compile-flags-incremental.rs
@@ -0,0 +1,17 @@
+//@ revisions: good bad bad-space
+//@ check-pass
+
+//@[bad] compile-flags: -Cincremental=true
+//@[bad] should-fail
+
+//@[bad-space] compile-flags:  -C  incremental=dir
+//@[bad-space] should-fail
+
+fn main() {}
+
+// Tests should not try to manually enable incremental compilation with
+// `-Cincremental`, because that typically results in stray directories being
+// created in the repository root.
+//
+// Instead, use the `//@ incremental` directive, which instructs compiletest
+// to handle the details of passing `-Cincremental` with a fresh directory.
diff --git a/tests/ui/coroutine/handle_opaques_before_coroutines.rs b/tests/ui/coroutine/handle_opaques_before_coroutines.rs
new file mode 100644
index 00000000000..2771c77429c
--- /dev/null
+++ b/tests/ui/coroutine/handle_opaques_before_coroutines.rs
@@ -0,0 +1,15 @@
+// test for https://github.com/rust-lang/trait-system-refactor-initiative/issues/239
+//@edition: 2024
+//@ check-pass
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
+
+fn foo<'a>() -> impl Send {
+    if false {
+        foo();
+    }
+    async {}
+}
+
+fn main() {}
diff --git a/tests/ui/error-codes/E0719.rs b/tests/ui/error-codes/E0719.rs
index 0ea6d19000b..d7b4b876d1b 100644
--- a/tests/ui/error-codes/E0719.rs
+++ b/tests/ui/error-codes/E0719.rs
@@ -1,8 +1,3 @@
-trait Foo: Iterator<Item = i32, Item = i32> {}
-//~^ ERROR is already specified
-//~| ERROR is already specified
-//~| ERROR is already specified
-
 type Unit = ();
 
 fn test() -> Box<dyn Iterator<Item = (), Item = Unit>> {
diff --git a/tests/ui/error-codes/E0719.stderr b/tests/ui/error-codes/E0719.stderr
index 7e8329db1f4..f4817568924 100644
--- a/tests/ui/error-codes/E0719.stderr
+++ b/tests/ui/error-codes/E0719.stderr
@@ -1,33 +1,5 @@
 error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/E0719.rs:1:33
-   |
-LL | trait Foo: Iterator<Item = i32, Item = i32> {}
-   |                     ----------  ^^^^^^^^^^ re-bound here
-   |                     |
-   |                     `Item` bound here first
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/E0719.rs:1:33
-   |
-LL | trait Foo: Iterator<Item = i32, Item = i32> {}
-   |                     ----------  ^^^^^^^^^^ re-bound here
-   |                     |
-   |                     `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/E0719.rs:1:33
-   |
-LL | trait Foo: Iterator<Item = i32, Item = i32> {}
-   |                     ----------  ^^^^^^^^^^ re-bound here
-   |                     |
-   |                     `Item` bound here first
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/E0719.rs:8:42
+  --> $DIR/E0719.rs:3:42
    |
 LL | fn test() -> Box<dyn Iterator<Item = (), Item = Unit>> {
    |                               ---------  ^^^^^^^^^^^ re-bound here
@@ -35,13 +7,13 @@ LL | fn test() -> Box<dyn Iterator<Item = (), Item = Unit>> {
    |                               `Item` bound here first
 
 error[E0719]: the value of the associated type `Item` in trait `Iterator` is already specified
-  --> $DIR/E0719.rs:14:38
+  --> $DIR/E0719.rs:9:38
    |
 LL |     let _: &dyn Iterator<Item = i32, Item = i32>;
    |                          ----------  ^^^^^^^^^^ re-bound here
    |                          |
    |                          `Item` bound here first
 
-error: aborting due to 5 previous errors
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0719`.
diff --git a/tests/ui/errors/auxiliary/remapped_dep.rs b/tests/ui/errors/auxiliary/remapped_dep.rs
index 36d4699a306..997118f822c 100644
--- a/tests/ui/errors/auxiliary/remapped_dep.rs
+++ b/tests/ui/errors/auxiliary/remapped_dep.rs
@@ -1,4 +1,4 @@
 //@ compile-flags: --remap-path-prefix={{src-base}}/errors/auxiliary=remapped-aux
-// no-remap-src-base: Manually remap, so the remapped path remains in .stderr file.
+// Manually remap, so the remapped path remains in .stderr file.
 
 pub struct SomeStruct {} // This line should be show as part of the error.
diff --git a/tests/ui/errors/remap-path-prefix-reverse.local-self.stderr b/tests/ui/errors/remap-path-prefix-reverse.local-self.stderr
index b4f83f6bfc0..b2651f3e03a 100644
--- a/tests/ui/errors/remap-path-prefix-reverse.local-self.stderr
+++ b/tests/ui/errors/remap-path-prefix-reverse.local-self.stderr
@@ -1,5 +1,5 @@
 error[E0423]: expected value, found struct `remapped_dep::SomeStruct`
-  --> $DIR/remap-path-prefix-reverse.rs:16:13
+  --> $DIR/remap-path-prefix-reverse.rs:15:13
    |
 LL |     let _ = remapped_dep::SomeStruct;
    |             ^^^^^^^^^^^^^^^^^^^^^^^^ help: use struct literal syntax instead: `remapped_dep::SomeStruct {}`
diff --git a/tests/ui/errors/remap-path-prefix-reverse.remapped-self.stderr b/tests/ui/errors/remap-path-prefix-reverse.remapped-self.stderr
index b4f83f6bfc0..b2651f3e03a 100644
--- a/tests/ui/errors/remap-path-prefix-reverse.remapped-self.stderr
+++ b/tests/ui/errors/remap-path-prefix-reverse.remapped-self.stderr
@@ -1,5 +1,5 @@
 error[E0423]: expected value, found struct `remapped_dep::SomeStruct`
-  --> $DIR/remap-path-prefix-reverse.rs:16:13
+  --> $DIR/remap-path-prefix-reverse.rs:15:13
    |
 LL |     let _ = remapped_dep::SomeStruct;
    |             ^^^^^^^^^^^^^^^^^^^^^^^^ help: use struct literal syntax instead: `remapped_dep::SomeStruct {}`
diff --git a/tests/ui/errors/remap-path-prefix-reverse.rs b/tests/ui/errors/remap-path-prefix-reverse.rs
index 28fdabb8f4d..562e44690f7 100644
--- a/tests/ui/errors/remap-path-prefix-reverse.rs
+++ b/tests/ui/errors/remap-path-prefix-reverse.rs
@@ -2,7 +2,6 @@
 //@ compile-flags: --remap-path-prefix={{src-base}}/errors/auxiliary=remapped-aux
 
 //@ revisions: local-self remapped-self
-// [local-self] no-remap-src-base: The hack should work regardless of remapping.
 //@ [remapped-self] remap-src-base
 
 // Verify that the expected source code is shown.
diff --git a/tests/ui/errors/remap-path-prefix.rs b/tests/ui/errors/remap-path-prefix.rs
index 7e38e16280f..de18aa8cc20 100644
--- a/tests/ui/errors/remap-path-prefix.rs
+++ b/tests/ui/errors/remap-path-prefix.rs
@@ -2,7 +2,7 @@
 //@ compile-flags: --remap-path-prefix={{src-base}}=remapped
 //@ [with-diagnostic-scope]compile-flags: -Zremap-path-scope=diagnostics
 //@ [without-diagnostic-scope]compile-flags: -Zremap-path-scope=object
-// no-remap-src-base: Manually remap, so the remapped path remains in .stderr file.
+// Manually remap, so the remapped path remains in .stderr file.
 
 // The remapped paths are not normalized by compiletest.
 //@ normalize-stderr: "\\(errors)" -> "/$1"
diff --git a/tests/ui/feature-gates/feature-gate-static_align-thread_local.rs b/tests/ui/feature-gates/feature-gate-static_align-thread_local.rs
new file mode 100644
index 00000000000..29d4facffce
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-static_align-thread_local.rs
@@ -0,0 +1,11 @@
+// The feature gate error may be emitted twice, but only on certain targets
+//@ dont-require-annotations: ERROR
+//@ dont-check-compiler-stderr
+
+#![crate_type = "lib"]
+
+thread_local! {
+    //~^ ERROR the `#[rustc_align_static]` attribute is an experimental feature
+    #[rustc_align_static(16)]
+    static THREAD_LOCAL: u16 = 0;
+}
diff --git a/tests/ui/indexing/ambiguity-after-deref-step.rs b/tests/ui/indexing/ambiguity-after-deref-step.rs
new file mode 100644
index 00000000000..2dd95eed097
--- /dev/null
+++ b/tests/ui/indexing/ambiguity-after-deref-step.rs
@@ -0,0 +1,9 @@
+// Regression test making sure that indexing fails with an ambiguity
+// error if one of the deref-steps encounters an inference variable.
+
+fn main() {
+    let x = &Default::default();
+    //~^ ERROR type annotations needed for `&_`
+    x[1];
+    let _: &Vec<()> = x;
+}
diff --git a/tests/ui/indexing/ambiguity-after-deref-step.stderr b/tests/ui/indexing/ambiguity-after-deref-step.stderr
new file mode 100644
index 00000000000..c7ddd4731c7
--- /dev/null
+++ b/tests/ui/indexing/ambiguity-after-deref-step.stderr
@@ -0,0 +1,17 @@
+error[E0282]: type annotations needed for `&_`
+  --> $DIR/ambiguity-after-deref-step.rs:5:9
+   |
+LL |     let x = &Default::default();
+   |         ^
+LL |
+LL |     x[1];
+   |     - type must be known at this point
+   |
+help: consider giving `x` an explicit type, where the placeholders `_` are specified
+   |
+LL |     let x: &_ = &Default::default();
+   |          ++++
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/tests/ui/indexing/index_message.stderr b/tests/ui/indexing/index_message.stderr
index 6affb1ed962..b6f61379f2a 100644
--- a/tests/ui/indexing/index_message.stderr
+++ b/tests/ui/indexing/index_message.stderr
@@ -2,7 +2,9 @@ error[E0608]: cannot index into a value of type `({integer},)`
   --> $DIR/index_message.rs:3:14
    |
 LL |     let _ = z[0];
-   |              ^^^ help: to access tuple elements, use: `.0`
+   |              ^^^ help: to access tuple element `0`, use: `.0`
+   |
+   = help: tuples are indexed with a dot and a literal index: `tuple.0`, `tuple.1`, etc.
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/issues/issue-27842.stderr b/tests/ui/issues/issue-27842.stderr
index b18fe1512b5..f388fdf85cd 100644
--- a/tests/ui/issues/issue-27842.stderr
+++ b/tests/ui/issues/issue-27842.stderr
@@ -2,17 +2,17 @@ error[E0608]: cannot index into a value of type `({integer}, {integer}, {integer
   --> $DIR/issue-27842.rs:4:16
    |
 LL |     let _ = tup[0];
-   |                ^^^ help: to access tuple elements, use: `.0`
+   |                ^^^ help: to access tuple element `0`, use: `.0`
+   |
+   = help: tuples are indexed with a dot and a literal index: `tuple.0`, `tuple.1`, etc.
 
 error[E0608]: cannot index into a value of type `({integer}, {integer}, {integer})`
   --> $DIR/issue-27842.rs:9:16
    |
 LL |     let _ = tup[i];
-   |                ^-^
-   |                 |
-   |                 cannot access tuple elements at a variable index
+   |                ^^^
    |
-   = help: to access tuple elements, use tuple indexing syntax (e.g., `tuple.0`)
+   = help: tuples are indexed with a dot and a literal index: `tuple.0`, `tuple.1`, etc.
 
 error[E0608]: cannot index into a value of type `({integer},)`
   --> $DIR/issue-27842.rs:14:16
@@ -20,7 +20,7 @@ error[E0608]: cannot index into a value of type `({integer},)`
 LL |     let _ = tup[3];
    |                ^^^
    |
-   = help: to access tuple elements, use tuple indexing syntax (e.g., `tuple.0`)
+   = help: tuples are indexed with a dot and a literal index: `tuple.0`, `tuple.1`, etc.
 
 error: aborting due to 3 previous errors
 
diff --git a/tests/ui/macros/macro-local-data-key-priv.stderr b/tests/ui/macros/macro-local-data-key-priv.stderr
index e93bd11046d..8df1aec140d 100644
--- a/tests/ui/macros/macro-local-data-key-priv.stderr
+++ b/tests/ui/macros/macro-local-data-key-priv.stderr
@@ -9,7 +9,7 @@ note: the constant `baz` is defined here
    |
 LL |     thread_local!(static baz: f64 = 0.0);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: this error originates in the macro `$crate::thread::local_impl::thread_local_inner` which comes from the expansion of the macro `thread_local` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `$crate::thread::local_impl::thread_local_process_attrs` which comes from the expansion of the macro `thread_local` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/macros/macro-rules-attr-error.rs b/tests/ui/macros/macro-rules-attr-error.rs
index 81eadb6692f..60290b883cb 100644
--- a/tests/ui/macros/macro-rules-attr-error.rs
+++ b/tests/ui/macros/macro-rules-attr-error.rs
@@ -50,3 +50,22 @@ macro_rules! forward_referenced_attr {
 macro_rules! cyclic_attr {
     attr() {} => {}
 }
+
+macro_rules! attr_with_safety {
+    unsafe attr() { struct RequiresUnsafe; } => {};
+    attr() { struct SafeInvocation; } => {};
+}
+
+#[attr_with_safety]
+struct SafeInvocation;
+
+//~v ERROR: unnecessary `unsafe` on safe attribute invocation
+#[unsafe(attr_with_safety)]
+struct SafeInvocation;
+
+//~v ERROR: unsafe attribute invocation requires `unsafe`
+#[attr_with_safety]
+struct RequiresUnsafe;
+
+#[unsafe(attr_with_safety)]
+struct RequiresUnsafe;
diff --git a/tests/ui/macros/macro-rules-attr-error.stderr b/tests/ui/macros/macro-rules-attr-error.stderr
index 674d35091b6..27527a2da7e 100644
--- a/tests/ui/macros/macro-rules-attr-error.stderr
+++ b/tests/ui/macros/macro-rules-attr-error.stderr
@@ -9,6 +9,18 @@ LL |     #[local_attr]
    |
    = note: this error originates in the attribute macro `local_attr` (in Nightly builds, run with -Z macro-backtrace for more info)
 
+error: unnecessary `unsafe` on safe attribute invocation
+  --> $DIR/macro-rules-attr-error.rs:63:3
+   |
+LL | #[unsafe(attr_with_safety)]
+   |   ^^^^^^
+
+error: unsafe attribute invocation requires `unsafe`
+  --> $DIR/macro-rules-attr-error.rs:67:1
+   |
+LL | #[attr_with_safety]
+   | ^^^^^^^^^^^^^^^^^^^
+
 error: cannot find macro `local_attr` in this scope
   --> $DIR/macro-rules-attr-error.rs:27:5
    |
@@ -59,5 +71,5 @@ note: a macro with the same name exists, but it appears later
 LL | macro_rules! cyclic_attr {
    |              ^^^^^^^^^^^
 
-error: aborting due to 6 previous errors
+error: aborting due to 8 previous errors
 
diff --git a/tests/ui/methods/overflow-if-subtyping.rs b/tests/ui/methods/overflow-if-subtyping.rs
new file mode 100644
index 00000000000..a97f29f1f6d
--- /dev/null
+++ b/tests/ui/methods/overflow-if-subtyping.rs
@@ -0,0 +1,30 @@
+//@ check-pass
+
+// Regression test for #128887.
+#![allow(unconditional_recursion)]
+trait Mappable<T> {
+    type Output;
+}
+
+trait Bound<T> {}
+// Deleting this impl made it compile on beta
+impl<T> Bound<T> for T {}
+
+trait Generic<M> {}
+
+// Deleting the `: Mappable<T>` already made it error on stable.
+struct IndexWithIter<I, M: Mappable<T>, T>(I, M, T);
+
+impl<I, M, T> IndexWithIter<I, M, T>
+where
+    <M as Mappable<T>>::Output: Bound<T>,
+    // Flipping these where bounds causes this to succeed, even when removing
+    // the where-clause on the struct definition.
+    M: Mappable<T>,
+    I: Generic<M>,
+{
+    fn new(x: I) {
+        IndexWithIter::<_, _, _>::new(x);
+    }
+}
+fn main() {}
diff --git a/tests/ui/parser/issues/issue-87086-colon-path-sep.rs b/tests/ui/parser/issues/issue-87086-colon-path-sep.rs
index d081c06044f..e1ea38f2795 100644
--- a/tests/ui/parser/issues/issue-87086-colon-path-sep.rs
+++ b/tests/ui/parser/issues/issue-87086-colon-path-sep.rs
@@ -37,10 +37,9 @@ fn g1() {
         //~| HELP: maybe write a path separator here
         _ => {}
     }
-    if let Foo:Bar = f() { //~ WARN: irrefutable `if let` pattern
+    if let Foo:Bar = f() {
     //~^ ERROR: expected one of
     //~| HELP: maybe write a path separator here
-    //~| HELP: consider replacing the `if let` with a `let`
     }
 }
 
diff --git a/tests/ui/parser/issues/issue-87086-colon-path-sep.stderr b/tests/ui/parser/issues/issue-87086-colon-path-sep.stderr
index a9bad96f9af..061586882e0 100644
--- a/tests/ui/parser/issues/issue-87086-colon-path-sep.stderr
+++ b/tests/ui/parser/issues/issue-87086-colon-path-sep.stderr
@@ -64,7 +64,7 @@ LL |     if let Foo::Bar = f() {
    |                +
 
 error: expected one of `@` or `|`, found `:`
-  --> $DIR/issue-87086-colon-path-sep.rs:49:16
+  --> $DIR/issue-87086-colon-path-sep.rs:48:16
    |
 LL |         ref qux: Foo::Baz => {}
    |                ^ -------- specifying the type of a pattern isn't supported
@@ -77,7 +77,7 @@ LL |         ref qux::Foo::Baz => {}
    |                ~~
 
 error: expected one of `@` or `|`, found `:`
-  --> $DIR/issue-87086-colon-path-sep.rs:58:16
+  --> $DIR/issue-87086-colon-path-sep.rs:57:16
    |
 LL |         mut qux: Foo::Baz => {}
    |                ^ -------- specifying the type of a pattern isn't supported
@@ -90,7 +90,7 @@ LL |         mut qux::Foo::Baz => {}
    |                ~~
 
 error: expected one of `@` or `|`, found `:`
-  --> $DIR/issue-87086-colon-path-sep.rs:69:12
+  --> $DIR/issue-87086-colon-path-sep.rs:68:12
    |
 LL |         Foo:Bar::Baz => {}
    |            ^-------- specifying the type of a pattern isn't supported
@@ -103,7 +103,7 @@ LL |         Foo::Bar::Baz => {}
    |             +
 
 error: expected one of `@` or `|`, found `:`
-  --> $DIR/issue-87086-colon-path-sep.rs:75:12
+  --> $DIR/issue-87086-colon-path-sep.rs:74:12
    |
 LL |         Foo:Bar => {}
    |            ^--- specifying the type of a pattern isn't supported
@@ -115,15 +115,5 @@ help: maybe write a path separator here
 LL |         Foo::Bar => {}
    |             +
 
-warning: irrefutable `if let` pattern
-  --> $DIR/issue-87086-colon-path-sep.rs:40:8
-   |
-LL |     if let Foo:Bar = f() {
-   |        ^^^^^^^^^^^^^^^^^
-   |
-   = note: this pattern will always match, so the `if let` is useless
-   = help: consider replacing the `if let` with a `let`
-   = note: `#[warn(irrefutable_let_patterns)]` on by default
-
-error: aborting due to 9 previous errors; 1 warning emitted
+error: aborting due to 9 previous errors
 
diff --git a/tests/ui/parser/macro/bad-macro-definition.rs b/tests/ui/parser/macro/bad-macro-definition.rs
index 3c5c93ea3b3..12df6e64bd2 100644
--- a/tests/ui/parser/macro/bad-macro-definition.rs
+++ b/tests/ui/parser/macro/bad-macro-definition.rs
@@ -20,3 +20,6 @@ macro_rules! e { {} }
 
 macro_rules! f {}
 //~^ ERROR: macros must contain at least one rule
+
+macro_rules! g { unsafe {} => {} }
+//~^ ERROR: `unsafe` is only supported on `attr` rules
diff --git a/tests/ui/parser/macro/bad-macro-definition.stderr b/tests/ui/parser/macro/bad-macro-definition.stderr
index de6d9d6a38b..d15f33f708d 100644
--- a/tests/ui/parser/macro/bad-macro-definition.stderr
+++ b/tests/ui/parser/macro/bad-macro-definition.stderr
@@ -52,5 +52,11 @@ error: macros must contain at least one rule
 LL | macro_rules! f {}
    | ^^^^^^^^^^^^^^^^^
 
-error: aborting due to 9 previous errors
+error: `unsafe` is only supported on `attr` rules
+  --> $DIR/bad-macro-definition.rs:24:18
+   |
+LL | macro_rules! g { unsafe {} => {} }
+   |                  ^^^^^^
+
+error: aborting due to 10 previous errors
 
diff --git a/tests/ui/parser/macro/macro-attr-bad.rs b/tests/ui/parser/macro/macro-attr-bad.rs
index 9f50b057a7a..0ac46c8b768 100644
--- a/tests/ui/parser/macro/macro-attr-bad.rs
+++ b/tests/ui/parser/macro/macro-attr-bad.rs
@@ -13,6 +13,12 @@ macro_rules! attr_incomplete_3 { attr() {} }
 macro_rules! attr_incomplete_4 { attr() {} => }
 //~^ ERROR macro definition ended unexpectedly
 
+macro_rules! attr_incomplete_5 { unsafe }
+//~^ ERROR macro definition ended unexpectedly
+
+macro_rules! attr_incomplete_6 { unsafe attr }
+//~^ ERROR macro definition ended unexpectedly
+
 macro_rules! attr_noparens_1 { attr{} {} => {} }
 //~^ ERROR `attr` rule argument matchers require parentheses
 
diff --git a/tests/ui/parser/macro/macro-attr-bad.stderr b/tests/ui/parser/macro/macro-attr-bad.stderr
index bf0ed13cd55..481ef8118ae 100644
--- a/tests/ui/parser/macro/macro-attr-bad.stderr
+++ b/tests/ui/parser/macro/macro-attr-bad.stderr
@@ -22,8 +22,20 @@ error: macro definition ended unexpectedly
 LL | macro_rules! attr_incomplete_4 { attr() {} => }
    |                                              ^ expected right-hand side of macro rule
 
+error: macro definition ended unexpectedly
+  --> $DIR/macro-attr-bad.rs:16:40
+   |
+LL | macro_rules! attr_incomplete_5 { unsafe }
+   |                                        ^ expected `attr`
+
+error: macro definition ended unexpectedly
+  --> $DIR/macro-attr-bad.rs:19:45
+   |
+LL | macro_rules! attr_incomplete_6 { unsafe attr }
+   |                                             ^ expected macro attr args
+
 error: `attr` rule argument matchers require parentheses
-  --> $DIR/macro-attr-bad.rs:16:36
+  --> $DIR/macro-attr-bad.rs:22:36
    |
 LL | macro_rules! attr_noparens_1 { attr{} {} => {} }
    |                                    ^^
@@ -35,7 +47,7 @@ LL + macro_rules! attr_noparens_1 { attr() {} => {} }
    |
 
 error: `attr` rule argument matchers require parentheses
-  --> $DIR/macro-attr-bad.rs:19:36
+  --> $DIR/macro-attr-bad.rs:25:36
    |
 LL | macro_rules! attr_noparens_2 { attr[] {} => {} }
    |                                    ^^
@@ -47,13 +59,13 @@ LL + macro_rules! attr_noparens_2 { attr() {} => {} }
    |
 
 error: invalid macro matcher; matchers must be contained in balanced delimiters
-  --> $DIR/macro-attr-bad.rs:22:37
+  --> $DIR/macro-attr-bad.rs:28:37
    |
 LL | macro_rules! attr_noparens_3 { attr _ {} => {} }
    |                                     ^
 
 error: duplicate matcher binding
-  --> $DIR/macro-attr-bad.rs:25:52
+  --> $DIR/macro-attr-bad.rs:31:52
    |
 LL | macro_rules! attr_dup_matcher_1 { attr() {$x:ident $x:ident} => {} }
    |                                           -------- ^^^^^^^^ duplicate binding
@@ -61,7 +73,7 @@ LL | macro_rules! attr_dup_matcher_1 { attr() {$x:ident $x:ident} => {} }
    |                                           previous binding
 
 error: duplicate matcher binding
-  --> $DIR/macro-attr-bad.rs:28:49
+  --> $DIR/macro-attr-bad.rs:34:49
    |
 LL | macro_rules! attr_dup_matcher_2 { attr($x:ident $x:ident) {} => {} }
    |                                        -------- ^^^^^^^^ duplicate binding
@@ -69,12 +81,12 @@ LL | macro_rules! attr_dup_matcher_2 { attr($x:ident $x:ident) {} => {} }
    |                                        previous binding
 
 error: duplicate matcher binding
-  --> $DIR/macro-attr-bad.rs:31:51
+  --> $DIR/macro-attr-bad.rs:37:51
    |
 LL | macro_rules! attr_dup_matcher_3 { attr($x:ident) {$x:ident} => {} }
    |                                        --------   ^^^^^^^^ duplicate binding
    |                                        |
    |                                        previous binding
 
-error: aborting due to 10 previous errors
+error: aborting due to 12 previous errors
 
diff --git a/tests/ui/parser/macro/macro-derive-bad.rs b/tests/ui/parser/macro/macro-derive-bad.rs
index 79b9eb8c113..74e7d9acdaf 100644
--- a/tests/ui/parser/macro/macro-derive-bad.rs
+++ b/tests/ui/parser/macro/macro-derive-bad.rs
@@ -41,3 +41,6 @@ macro_rules! derive_dup_matcher { derive() {$x:ident $x:ident} => {} }
 //~^ ERROR duplicate matcher binding
 //~| NOTE duplicate binding
 //~| NOTE previous binding
+
+macro_rules! derive_unsafe { unsafe derive() {} => {} }
+//~^ ERROR `unsafe` is only supported on `attr` rules
diff --git a/tests/ui/parser/macro/macro-derive-bad.stderr b/tests/ui/parser/macro/macro-derive-bad.stderr
index ec750c9ac82..c98535f4031 100644
--- a/tests/ui/parser/macro/macro-derive-bad.stderr
+++ b/tests/ui/parser/macro/macro-derive-bad.stderr
@@ -86,5 +86,11 @@ LL | macro_rules! derive_dup_matcher { derive() {$x:ident $x:ident} => {} }
    |                                             |
    |                                             previous binding
 
-error: aborting due to 12 previous errors
+error: `unsafe` is only supported on `attr` rules
+  --> $DIR/macro-derive-bad.rs:45:30
+   |
+LL | macro_rules! derive_unsafe { unsafe derive() {} => {} }
+   |                              ^^^^^^
+
+error: aborting due to 13 previous errors
 
diff --git a/tests/ui/parser/type-ascription-in-pattern.rs b/tests/ui/parser/type-ascription-in-pattern.rs
index 18d7061d69c..75059d33db6 100644
--- a/tests/ui/parser/type-ascription-in-pattern.rs
+++ b/tests/ui/parser/type-ascription-in-pattern.rs
@@ -1,15 +1,16 @@
 fn foo(x: bool) -> i32 {
-    match x { //~ ERROR struct literals are not allowed here
-        x: i32 => x, //~ ERROR expected
-        true => 42., //~ ERROR expected identifier
-        false => 0.333, //~ ERROR expected identifier
+    match x {
+        x: i32 => x, //~ ERROR: expected
+        //~^ ERROR: mismatched types
+        true => 42.,
+        false => 0.333,
     }
-} //~ ERROR expected one of
+}
 
 fn main() {
     match foo(true) {
-        42: i32 => (), //~ ERROR expected
-        _: f64 => (), //~ ERROR expected
-        x: i32 => (), //~ ERROR expected
+        42: i32 => (), //~ ERROR: expected
+        _: f64 => (), //~ ERROR: expected
+        x: i32 => (), //~ ERROR: expected
     }
 }
diff --git a/tests/ui/parser/type-ascription-in-pattern.stderr b/tests/ui/parser/type-ascription-in-pattern.stderr
index 135879f208b..09190754993 100644
--- a/tests/ui/parser/type-ascription-in-pattern.stderr
+++ b/tests/ui/parser/type-ascription-in-pattern.stderr
@@ -1,64 +1,18 @@
-error: expected one of `!`, `,`, `.`, `::`, `?`, `{`, `}`, or an operator, found `=>`
-  --> $DIR/type-ascription-in-pattern.rs:3:16
-   |
-LL |     match x {
-   |           - while parsing this struct
-LL |         x: i32 => x,
-   |               -^^ expected one of 8 possible tokens
-   |               |
-   |               help: try adding a comma: `,`
-
-error: expected identifier, found keyword `true`
-  --> $DIR/type-ascription-in-pattern.rs:4:9
-   |
-LL |     match x {
-   |           - while parsing this struct
-LL |         x: i32 => x,
-LL |         true => 42.,
-   |         ^^^^ expected identifier, found keyword
-
-error: expected identifier, found keyword `false`
-  --> $DIR/type-ascription-in-pattern.rs:5:9
-   |
-LL |     match x {
-   |           - while parsing this struct
-...
-LL |         false => 0.333,
-   |         ^^^^^ expected identifier, found keyword
-
-error: struct literals are not allowed here
-  --> $DIR/type-ascription-in-pattern.rs:2:11
-   |
-LL |       match x {
-   |  ___________^
-LL | |         x: i32 => x,
-LL | |         true => 42.,
-LL | |         false => 0.333,
-LL | |     }
-   | |_____^
-   |
-help: surround the struct literal with parentheses
+error: expected one of `@` or `|`, found `:`
+  --> $DIR/type-ascription-in-pattern.rs:3:10
    |
-LL ~     match (x {
 LL |         x: i32 => x,
-LL |         true => 42.,
-LL |         false => 0.333,
-LL ~     })
+   |          ^ --- specifying the type of a pattern isn't supported
+   |          |
+   |          expected one of `@` or `|`
    |
-
-error: expected one of `.`, `?`, `{`, or an operator, found `}`
-  --> $DIR/type-ascription-in-pattern.rs:7:1
+help: maybe write a path separator here
    |
-LL |     match x {
-   |     ----- while parsing this `match` expression
-...
-LL |     }
-   |      - expected one of `.`, `?`, `{`, or an operator
-LL | }
-   | ^ unexpected token
+LL |         x::i32 => x,
+   |          ~~
 
 error: expected one of `...`, `..=`, `..`, or `|`, found `:`
-  --> $DIR/type-ascription-in-pattern.rs:11:11
+  --> $DIR/type-ascription-in-pattern.rs:12:11
    |
 LL |         42: i32 => (),
    |           ^ --- specifying the type of a pattern isn't supported
@@ -66,7 +20,7 @@ LL |         42: i32 => (),
    |           expected one of `...`, `..=`, `..`, or `|`
 
 error: expected `|`, found `:`
-  --> $DIR/type-ascription-in-pattern.rs:12:10
+  --> $DIR/type-ascription-in-pattern.rs:13:10
    |
 LL |         _: f64 => (),
    |          ^ --- specifying the type of a pattern isn't supported
@@ -74,7 +28,7 @@ LL |         _: f64 => (),
    |          expected `|`
 
 error: expected one of `@` or `|`, found `:`
-  --> $DIR/type-ascription-in-pattern.rs:13:10
+  --> $DIR/type-ascription-in-pattern.rs:14:10
    |
 LL |         x: i32 => (),
    |          ^ --- specifying the type of a pattern isn't supported
@@ -86,5 +40,15 @@ help: maybe write a path separator here
 LL |         x::i32 => (),
    |          ~~
 
-error: aborting due to 8 previous errors
+error[E0308]: mismatched types
+  --> $DIR/type-ascription-in-pattern.rs:3:19
+   |
+LL | fn foo(x: bool) -> i32 {
+   |                    --- expected `i32` because of return type
+LL |     match x {
+LL |         x: i32 => x,
+   |                   ^ expected `i32`, found `bool`
+
+error: aborting due to 5 previous errors
 
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/proc-macro/expand-expr.rs b/tests/ui/proc-macro/expand-expr.rs
index 1e058abe3bc..c3dddd8e459 100644
--- a/tests/ui/proc-macro/expand-expr.rs
+++ b/tests/ui/proc-macro/expand-expr.rs
@@ -1,6 +1,6 @@
 //@ proc-macro: expand-expr.rs
 //@ ignore-backends: gcc
-// no-remap-src-base: check_expand_expr_file!() fails when enabled.
+// No `remap-src-base`, since `check_expand_expr_file!()` fails when enabled.
 
 #![feature(concat_bytes)]
 extern crate expand_expr;
diff --git a/tests/ui/proc-macro/pretty-print-hack-show.rs b/tests/ui/proc-macro/pretty-print-hack-show.rs
index 70f0d5f6ea9..08e26c81142 100644
--- a/tests/ui/proc-macro/pretty-print-hack-show.rs
+++ b/tests/ui/proc-macro/pretty-print-hack-show.rs
@@ -1,7 +1,6 @@
 //@ proc-macro: test-macros.rs
 //@ compile-flags: -Z span-debug
 //@ revisions: local remapped
-// [local] no-remap-src-base: The hack should work regardless of remapping.
 //@ [remapped] remap-src-base
 
 #![no_std] // Don't load unnecessary hygiene information from std
diff --git a/tests/ui/span/suggestion-non-ascii.stderr b/tests/ui/span/suggestion-non-ascii.stderr
index 6e6e31a5698..361f744ee8e 100644
--- a/tests/ui/span/suggestion-non-ascii.stderr
+++ b/tests/ui/span/suggestion-non-ascii.stderr
@@ -2,7 +2,9 @@ error[E0608]: cannot index into a value of type `({integer},)`
   --> $DIR/suggestion-non-ascii.rs:3:24
    |
 LL |     println!("☃{}", tup[0]);
-   |                        ^^^ help: to access tuple elements, use: `.0`
+   |                        ^^^ help: to access tuple element `0`, use: `.0`
+   |
+   = help: tuples are indexed with a dot and a literal index: `tuple.0`, `tuple.1`, etc.
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/static/static-align.rs b/tests/ui/static/static-align.rs
index 93241db09f9..e2db7c01adf 100644
--- a/tests/ui/static/static-align.rs
+++ b/tests/ui/static/static-align.rs
@@ -1,10 +1,14 @@
 //@ run-pass
+//@ compile-flags: --cfg FOURTY_TWO="42" --cfg TRUE --check-cfg=cfg(FOURTY_TWO,values("42")) --check-cfg=cfg(TRUE)
 #![feature(static_align)]
+#![deny(non_upper_case_globals)]
+
+use std::cell::Cell;
 
 #[rustc_align_static(64)]
 static A: u8 = 0;
 
-#[rustc_align_static(64)]
+#[rustc_align_static(4096)]
 static B: u8 = 0;
 
 #[rustc_align_static(128)]
@@ -17,10 +21,86 @@ unsafe extern "C" {
     static C: u64;
 }
 
+struct HasDrop(*const HasDrop);
+
+impl Drop for HasDrop {
+    fn drop(&mut self) {
+        assert_eq!(core::ptr::from_mut(self).cast_const(), self.0);
+    }
+}
+
+thread_local! {
+    #[rustc_align_static(4096)]
+    static LOCAL: u64 = 0;
+
+    #[allow(unused_mut, reason = "test attribute handling")]
+    #[cfg_attr(true, rustc_align_static(4096))]
+    static CONST_LOCAL: u64 = const { 0 };
+
+    #[cfg_attr(any(true), cfg_attr(true, rustc_align_static(4096)))]
+    #[allow(unused_mut, reason = "test attribute handling")]
+    static HASDROP_LOCAL: Cell<HasDrop> = Cell::new(HasDrop(core::ptr::null()));
+
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    #[allow(unused_mut, reason = "test attribute handling")]
+    #[cfg_attr(TRUE,
+      cfg_attr(FOURTY_TWO = "42",
+      cfg_attr(all(),
+      cfg_attr(any(true),
+      cfg_attr(true, rustc_align_static(4096))))))]
+    #[allow(unused_mut, reason = "test attribute handling")]
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    static HASDROP_CONST_LOCAL: Cell<HasDrop> = const { Cell::new(HasDrop(core::ptr::null())) };
+
+    #[cfg_attr(TRUE,)]
+    #[cfg_attr(true,)]
+    #[cfg_attr(false,)]
+    #[cfg_attr(
+        TRUE,
+        rustc_align_static(32),
+        cfg_attr(true, allow(non_upper_case_globals, reason = "test attribute handling")),
+        cfg_attr(false,)
+    )]
+    #[cfg_attr(false, rustc_align_static(0))]
+    static more_attr_testing: u64 = 0;
+}
+
+fn thread_local_ptr<T>(key: &'static std::thread::LocalKey<T>) -> *const T {
+    key.with(|local| core::ptr::from_ref::<T>(local))
+}
+
 fn main() {
     assert!(core::ptr::from_ref(&A).addr().is_multiple_of(64));
-    assert!(core::ptr::from_ref(&B).addr().is_multiple_of(64));
+    assert!(core::ptr::from_ref(&B).addr().is_multiple_of(4096));
 
     assert!(core::ptr::from_ref(&EXPORTED).addr().is_multiple_of(128));
     unsafe { assert!(core::ptr::from_ref(&C).addr().is_multiple_of(128)) };
+
+    assert!(thread_local_ptr(&LOCAL).addr().is_multiple_of(4096));
+    assert!(thread_local_ptr(&CONST_LOCAL).addr().is_multiple_of(4096));
+    assert!(thread_local_ptr(&HASDROP_LOCAL).addr().is_multiple_of(4096));
+    assert!(thread_local_ptr(&HASDROP_CONST_LOCAL).addr().is_multiple_of(4096));
+    assert!(thread_local_ptr(&more_attr_testing).addr().is_multiple_of(32));
+
+    // Test that address (and therefore alignment) is maintained during drop
+    let hasdrop_ptr = thread_local_ptr(&HASDROP_LOCAL);
+    core::mem::forget(HASDROP_LOCAL.replace(HasDrop(hasdrop_ptr.cast())));
+    let hasdrop_const_ptr = thread_local_ptr(&HASDROP_CONST_LOCAL);
+    core::mem::forget(HASDROP_CONST_LOCAL.replace(HasDrop(hasdrop_const_ptr.cast())));
 }
diff --git a/tests/ui/thread-local/long-docs.rs b/tests/ui/thread-local/long-docs.rs
new file mode 100644
index 00000000000..0577d0b27c2
--- /dev/null
+++ b/tests/ui/thread-local/long-docs.rs
@@ -0,0 +1,266 @@
+//@ check-pass
+
+thread_local! {
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    pub static LONG_DOCS: () = ();
+
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    #[allow(unused_mut, reason = "testing")]
+    pub static LONG_DOCS_2: () = ();
+}
+
+fn main() {}
diff --git a/tests/ui/thread-local/no-unstable.rs b/tests/ui/thread-local/no-unstable.rs
new file mode 100644
index 00000000000..3de7985e62d
--- /dev/null
+++ b/tests/ui/thread-local/no-unstable.rs
@@ -0,0 +1,17 @@
+thread_local! {
+    //~^ ERROR: use of an internal attribute [E0658]
+    //~| ERROR: use of an internal attribute [E0658]
+    //~| ERROR: `#[used(linker)]` is currently unstable [E0658]
+    //~| ERROR: `#[used]` attribute cannot be used on constants
+
+    #[rustc_dummy = 17]
+    pub static FOO: () = ();
+
+    #[cfg_attr(true, rustc_dummy = 17)]
+    pub static BAR: () = ();
+
+    #[used(linker)]
+    pub static BAZ: () = ();
+}
+
+fn main() {}
diff --git a/tests/ui/thread-local/no-unstable.stderr b/tests/ui/thread-local/no-unstable.stderr
new file mode 100644
index 00000000000..fbcd804d917
--- /dev/null
+++ b/tests/ui/thread-local/no-unstable.stderr
@@ -0,0 +1,57 @@
+error[E0658]: use of an internal attribute
+  --> $DIR/no-unstable.rs:1:1
+   |
+LL | / thread_local! {
+...  |
+LL | |     pub static BAZ: () = ();
+LL | | }
+   | |_^
+   |
+   = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
+   = note: the `#[rustc_dummy]` attribute is an internal implementation detail that will never be stable
+   = note: the `#[rustc_dummy]` attribute is used for rustc unit tests
+   = note: this error originates in the macro `$crate::thread::local_impl::thread_local_process_attrs` which comes from the expansion of the macro `thread_local` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0658]: use of an internal attribute
+  --> $DIR/no-unstable.rs:1:1
+   |
+LL | / thread_local! {
+...  |
+LL | |     pub static BAZ: () = ();
+LL | | }
+   | |_^
+   |
+   = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
+   = note: the `#[rustc_dummy]` attribute is an internal implementation detail that will never be stable
+   = note: the `#[rustc_dummy]` attribute is used for rustc unit tests
+   = note: this error originates in the macro `$crate::thread::local_impl::thread_local_process_attrs` which comes from the expansion of the macro `thread_local` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0658]: `#[used(linker)]` is currently unstable
+  --> $DIR/no-unstable.rs:1:1
+   |
+LL | / thread_local! {
+...  |
+LL | |     pub static BAZ: () = ();
+LL | | }
+   | |_^
+   |
+   = note: see issue #93798 <https://github.com/rust-lang/rust/issues/93798> for more information
+   = help: add `#![feature(used_with_arg)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = note: this error originates in the macro `$crate::thread::local_impl::thread_local_process_attrs` which comes from the expansion of the macro `thread_local` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: `#[used]` attribute cannot be used on constants
+  --> $DIR/no-unstable.rs:1:1
+   |
+LL | / thread_local! {
+...  |
+LL | |     pub static BAZ: () = ();
+LL | | }
+   | |_^
+   |
+   = help: `#[used]` can only be applied to statics
+   = note: this error originates in the macro `$crate::thread::local_impl::thread_local_process_attrs` which comes from the expansion of the macro `thread_local` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/traits/next-solver/forced-ambiguity-typenum-ice.rs b/tests/ui/traits/next-solver/forced-ambiguity-typenum-ice.rs
new file mode 100644
index 00000000000..679d6b1fb16
--- /dev/null
+++ b/tests/ui/traits/next-solver/forced-ambiguity-typenum-ice.rs
@@ -0,0 +1,60 @@
+//@ compile-flags: -Znext-solver
+//@ check-pass
+
+// Regression test for trait-system-refactor-initiative#105. We previously encountered
+// an ICE in typenum as `forced_ambiguity` failed. While this test no longer causes
+// `forced_ambiguity` to error, we still want to use it as a regression test.
+
+pub struct UInt<U, B> {
+    _msb: U,
+    _lsb: B,
+}
+pub struct B1;
+pub trait Sub<Rhs> {
+    type Output;
+}
+impl<U, B> Sub<B1> for UInt<UInt<U, B>, B1> {
+    type Output = ();
+}
+impl<U> Sub<B1> for UInt<U, ()>
+where
+    U: Sub<B1>,
+    U::Output: Send,
+{
+    type Output = ();
+}
+
+pub trait Op<N, R, I> {
+    fn op(&self) {
+        unimplemented!()
+    }
+}
+trait OpIf<N, R, I> {}
+
+impl<N, Ur, Br, I> Op<N, UInt<Ur, Br>, I> for ()
+where
+    N: Sub<I>,
+    (): OpIf<N, UInt<UInt<Ur, Br>, N::Output>, I>,
+{
+}
+impl<N, R, Ui, Bi> OpIf<N, R, UInt<Ui, Bi>> for ()
+where
+    UInt<Ui, Bi>: Sub<B1>,
+    (): Op<N, R, <UInt<Ui, Bi> as Sub<B1>>::Output>,
+{
+}
+impl<N, R> OpIf<N, R, ()> for () where R: Sub<N> {}
+
+pub trait Compute {
+    type Output;
+}
+
+pub fn repro<Ul, Bl>()
+where
+    UInt<Ul, Bl>: Compute,
+    <UInt<Ul, Bl> as Compute>::Output: Sub<B1>,
+    (): Op<UInt<(), Bl>, (), ()>,
+{
+    ().op();
+}
+fn main() {}
diff --git a/tests/ui/type/pattern_types/const_generics.rs b/tests/ui/type/pattern_types/const_generics.rs
index 79d46c010d7..f5eb90e94d4 100644
--- a/tests/ui/type/pattern_types/const_generics.rs
+++ b/tests/ui/type/pattern_types/const_generics.rs
@@ -1,4 +1,7 @@
 //@ check-pass
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
 
 #![feature(pattern_types, generic_pattern_types, pattern_type_macro)]
 #![expect(incomplete_features)]
diff --git a/tests/ui/type/pattern_types/transmute.stderr b/tests/ui/type/pattern_types/transmute.current.stderr
index 578549b515c..edec542e5e1 100644
--- a/tests/ui/type/pattern_types/transmute.stderr
+++ b/tests/ui/type/pattern_types/transmute.current.stderr
@@ -1,5 +1,5 @@
 error[E0512]: cannot transmute between types of different sizes, or dependently-sized types
-  --> $DIR/transmute.rs:20:14
+  --> $DIR/transmute.rs:23:14
    |
 LL |     unsafe { std::mem::transmute(x) }
    |              ^^^^^^^^^^^^^^^^^^^
@@ -8,7 +8,7 @@ LL |     unsafe { std::mem::transmute(x) }
    = note: target type: `u32` (32 bits)
 
 error[E0512]: cannot transmute between types of different sizes, or dependently-sized types
-  --> $DIR/transmute.rs:28:14
+  --> $DIR/transmute.rs:31:14
    |
 LL |     unsafe { std::mem::transmute(x) }
    |              ^^^^^^^^^^^^^^^^^^^
diff --git a/tests/ui/type/pattern_types/transmute.next.stderr b/tests/ui/type/pattern_types/transmute.next.stderr
new file mode 100644
index 00000000000..edec542e5e1
--- /dev/null
+++ b/tests/ui/type/pattern_types/transmute.next.stderr
@@ -0,0 +1,21 @@
+error[E0512]: cannot transmute between types of different sizes, or dependently-sized types
+  --> $DIR/transmute.rs:23:14
+   |
+LL |     unsafe { std::mem::transmute(x) }
+   |              ^^^^^^^^^^^^^^^^^^^
+   |
+   = note: source type: `Option<(u32) is S..=E>` (size can vary because of u32)
+   = note: target type: `u32` (32 bits)
+
+error[E0512]: cannot transmute between types of different sizes, or dependently-sized types
+  --> $DIR/transmute.rs:31:14
+   |
+LL |     unsafe { std::mem::transmute(x) }
+   |              ^^^^^^^^^^^^^^^^^^^
+   |
+   = note: source type: `Option<(u32) is S..=E>` (size can vary because of u32)
+   = note: target type: `Option<u32>` (64 bits)
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0512`.
diff --git a/tests/ui/type/pattern_types/transmute.rs b/tests/ui/type/pattern_types/transmute.rs
index 43dd62a19e7..4e686245f93 100644
--- a/tests/ui/type/pattern_types/transmute.rs
+++ b/tests/ui/type/pattern_types/transmute.rs
@@ -1,3 +1,6 @@
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
 #![feature(pattern_types, pattern_type_macro, generic_pattern_types)]
 #![expect(incomplete_features)]
 
diff --git a/tests/ui/typeck/coercion-check-for-indexing-expression-issue-40861.stderr b/tests/ui/typeck/coercion-check-for-indexing-expression-issue-40861.stderr
index 13bc0cd94f3..ef5f1786801 100644
--- a/tests/ui/typeck/coercion-check-for-indexing-expression-issue-40861.stderr
+++ b/tests/ui/typeck/coercion-check-for-indexing-expression-issue-40861.stderr
@@ -4,7 +4,7 @@ error[E0608]: cannot index into a value of type `()`
 LL |     ()[f(&[1.0])];
    |       ^^^^^^^^^^^
    |
-   = help: to access tuple elements, use tuple indexing syntax (e.g., `tuple.0`)
+   = help: tuples are indexed with a dot and a literal index: `tuple.0`, `tuple.1`, etc.
 
 error: aborting due to 1 previous error