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-rw-r--r--Cargo.lock22
-rw-r--r--Cargo.toml1
-rw-r--r--compiler/rustc_ast_lowering/src/item.rs63
-rw-r--r--compiler/rustc_ast_lowering/src/lib.rs2
-rw-r--r--compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs5
-rw-r--r--compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs108
-rw-r--r--compiler/rustc_borrowck/src/lib.rs3
-rw-r--r--compiler/rustc_borrowck/src/nll.rs3
-rw-r--r--compiler/rustc_borrowck/src/region_infer/mod.rs71
-rw-r--r--compiler/rustc_borrowck/src/region_infer/opaque_types.rs17
-rw-r--r--compiler/rustc_borrowck/src/renumber.rs22
-rw-r--r--compiler/rustc_borrowck/src/type_check/canonical.rs6
-rw-r--r--compiler/rustc_borrowck/src/type_check/constraint_conversion.rs3
-rw-r--r--compiler/rustc_borrowck/src/type_check/input_output.rs9
-rw-r--r--compiler/rustc_borrowck/src/type_check/mod.rs52
-rw-r--r--compiler/rustc_borrowck/src/type_check/relate_tys.rs2
-rwxr-xr-xcompiler/rustc_codegen_cranelift/scripts/filter_profile.rs2
-rw-r--r--compiler/rustc_codegen_cranelift/src/driver/aot.rs2
-rw-r--r--compiler/rustc_codegen_cranelift/src/lib.rs2
-rw-r--r--compiler/rustc_codegen_cranelift/src/metadata.rs10
-rw-r--r--compiler/rustc_codegen_gcc/.github/workflows/main.yml96
-rw-r--r--compiler/rustc_codegen_gcc/.gitignore20
-rw-r--r--compiler/rustc_codegen_gcc/Cargo.lock373
-rw-r--r--compiler/rustc_codegen_gcc/Cargo.toml51
-rw-r--r--compiler/rustc_codegen_gcc/LICENSE-APACHE176
-rw-r--r--compiler/rustc_codegen_gcc/LICENSE-MIT23
-rw-r--r--compiler/rustc_codegen_gcc/Readme.md135
-rwxr-xr-xcompiler/rustc_codegen_gcc/build.sh31
-rw-r--r--compiler/rustc_codegen_gcc/build_sysroot/Cargo.toml19
-rwxr-xr-xcompiler/rustc_codegen_gcc/build_sysroot/build_sysroot.sh30
-rwxr-xr-xcompiler/rustc_codegen_gcc/build_sysroot/prepare_sysroot_src.sh39
-rw-r--r--compiler/rustc_codegen_gcc/build_sysroot/src/lib.rs1
-rwxr-xr-xcompiler/rustc_codegen_gcc/cargo.sh23
-rwxr-xr-xcompiler/rustc_codegen_gcc/clean_all.sh5
-rw-r--r--compiler/rustc_codegen_gcc/config.sh52
-rw-r--r--compiler/rustc_codegen_gcc/example/alloc_example.rs41
-rw-r--r--compiler/rustc_codegen_gcc/example/alloc_system.rs212
-rw-r--r--compiler/rustc_codegen_gcc/example/arbitrary_self_types_pointers_and_wrappers.rs69
-rw-r--r--compiler/rustc_codegen_gcc/example/dst-field-align.rs67
-rw-r--r--compiler/rustc_codegen_gcc/example/example.rs208
-rw-r--r--compiler/rustc_codegen_gcc/example/mini_core.rs585
-rw-r--r--compiler/rustc_codegen_gcc/example/mini_core_hello_world.rs424
-rw-r--r--compiler/rustc_codegen_gcc/example/mod_bench.rs37
-rw-r--r--compiler/rustc_codegen_gcc/example/std_example.rs278
-rw-r--r--compiler/rustc_codegen_gcc/example/subslice-patterns-const-eval.rs97
-rw-r--r--compiler/rustc_codegen_gcc/example/track-caller-attribute.rs40
-rw-r--r--compiler/rustc_codegen_gcc/patches/0022-core-Disable-not-compiling-tests.patch63
-rw-r--r--compiler/rustc_codegen_gcc/patches/0023-core-Ignore-failing-tests.patch49
-rwxr-xr-xcompiler/rustc_codegen_gcc/prepare.sh22
-rwxr-xr-xcompiler/rustc_codegen_gcc/prepare_build.sh5
-rw-r--r--compiler/rustc_codegen_gcc/rust-toolchain1
-rwxr-xr-xcompiler/rustc_codegen_gcc/rustup.sh29
-rw-r--r--compiler/rustc_codegen_gcc/src/abi.rs160
-rw-r--r--compiler/rustc_codegen_gcc/src/allocator.rs116
-rw-r--r--compiler/rustc_codegen_gcc/src/archive.rs218
-rw-r--r--compiler/rustc_codegen_gcc/src/asm.rs785
-rw-r--r--compiler/rustc_codegen_gcc/src/back/mod.rs1
-rw-r--r--compiler/rustc_codegen_gcc/src/back/write.rs78
-rw-r--r--compiler/rustc_codegen_gcc/src/base.rs165
-rw-r--r--compiler/rustc_codegen_gcc/src/builder.rs1540
-rw-r--r--compiler/rustc_codegen_gcc/src/callee.rs77
-rw-r--r--compiler/rustc_codegen_gcc/src/common.rs450
-rw-r--r--compiler/rustc_codegen_gcc/src/consts.rs390
-rw-r--r--compiler/rustc_codegen_gcc/src/context.rs475
-rw-r--r--compiler/rustc_codegen_gcc/src/coverageinfo.rs69
-rw-r--r--compiler/rustc_codegen_gcc/src/debuginfo.rs62
-rw-r--r--compiler/rustc_codegen_gcc/src/declare.rs144
-rw-r--r--compiler/rustc_codegen_gcc/src/intrinsic/llvm.rs22
-rw-r--r--compiler/rustc_codegen_gcc/src/intrinsic/mod.rs1067
-rw-r--r--compiler/rustc_codegen_gcc/src/intrinsic/simd.rs167
-rw-r--r--compiler/rustc_codegen_gcc/src/lib.rs293
-rw-r--r--compiler/rustc_codegen_gcc/src/mono_item.rs38
-rw-r--r--compiler/rustc_codegen_gcc/src/type_.rs282
-rw-r--r--compiler/rustc_codegen_gcc/src/type_of.rs359
-rwxr-xr-xcompiler/rustc_codegen_gcc/test.sh217
-rw-r--r--compiler/rustc_codegen_gcc/tests/lib.rs50
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/abort1.rs51
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/abort2.rs53
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/array.rs229
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/asm.rs153
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/assign.rs153
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/closure.rs230
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/condition.rs320
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/empty_main.rs39
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/exit.rs49
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/exit_code.rs39
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/fun_ptr.rs223
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/int_overflow.rs129
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/mut_ref.rs165
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/operations.rs221
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/ptr_cast.rs222
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/return-tuple.rs72
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/slice.rs128
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/static.rs106
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/structs.rs70
-rw-r--r--compiler/rustc_codegen_gcc/tests/run/tuple.rs51
-rw-r--r--compiler/rustc_codegen_llvm/src/back/write.rs3
-rw-r--r--compiler/rustc_codegen_llvm/src/base.rs4
-rw-r--r--compiler/rustc_codegen_llvm/src/context.rs7
-rw-r--r--compiler/rustc_codegen_llvm/src/lib.rs15
-rw-r--r--compiler/rustc_codegen_llvm/src/mono_item.rs6
-rw-r--r--compiler/rustc_codegen_ssa/Cargo.toml1
-rw-r--r--compiler/rustc_codegen_ssa/src/back/link.rs10
-rw-r--r--compiler/rustc_codegen_ssa/src/back/write.rs2
-rw-r--r--compiler/rustc_codegen_ssa/src/base.rs2
-rw-r--r--compiler/rustc_codegen_ssa/src/lib.rs2
-rw-r--r--compiler/rustc_codegen_ssa/src/traits/backend.rs3
-rw-r--r--compiler/rustc_const_eval/src/interpret/step.rs17
-rw-r--r--compiler/rustc_data_structures/src/graph/scc/mod.rs20
-rw-r--r--compiler/rustc_expand/src/expand.rs8
-rw-r--r--compiler/rustc_hir/src/hir.rs10
-rw-r--r--compiler/rustc_hir/src/lang_items.rs2
-rw-r--r--compiler/rustc_infer/src/infer/at.rs8
-rw-r--r--compiler/rustc_infer/src/infer/canonical/query_response.rs11
-rw-r--r--compiler/rustc_infer/src/infer/fudge.rs3
-rw-r--r--compiler/rustc_infer/src/infer/higher_ranked/mod.rs3
-rw-r--r--compiler/rustc_infer/src/infer/mod.rs16
-rw-r--r--compiler/rustc_infer/src/infer/nll_relate/mod.rs28
-rw-r--r--compiler/rustc_infer/src/infer/region_constraints/mod.rs6
-rw-r--r--compiler/rustc_interface/src/passes.rs15
-rw-r--r--compiler/rustc_interface/src/queries.rs4
-rw-r--r--compiler/rustc_lint/src/context.rs15
-rw-r--r--compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp4
-rw-r--r--compiler/rustc_metadata/src/lib.rs2
-rw-r--r--compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs7
-rw-r--r--compiler/rustc_metadata/src/rmeta/encoder.rs23
-rw-r--r--compiler/rustc_metadata/src/rmeta/mod.rs1
-rw-r--r--compiler/rustc_middle/Cargo.toml2
-rw-r--r--compiler/rustc_middle/src/middle/cstore.rs16
-rw-r--r--compiler/rustc_middle/src/middle/stability.rs114
-rw-r--r--compiler/rustc_middle/src/ty/context.rs6
-rw-r--r--compiler/rustc_middle/src/ty/fold.rs36
-rw-r--r--compiler/rustc_middle/src/ty/layout.rs48
-rw-r--r--compiler/rustc_middle/src/ty/mod.rs38
-rw-r--r--compiler/rustc_middle/src/ty/print/mod.rs4
-rw-r--r--compiler/rustc_middle/src/ty/print/pretty.rs8
-rw-r--r--compiler/rustc_middle/src/ty/util.rs2
-rw-r--r--compiler/rustc_mir_build/src/build/expr/into.rs9
-rw-r--r--compiler/rustc_mir_build/src/thir/cx/expr.rs19
-rw-r--r--compiler/rustc_mir_build/src/thir/cx/mod.rs10
-rw-r--r--compiler/rustc_mir_build/src/thir/pattern/check_match.rs261
-rw-r--r--compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs964
-rw-r--r--compiler/rustc_mir_build/src/thir/pattern/usefulness.rs599
-rw-r--r--compiler/rustc_mir_dataflow/src/impls/mod.rs18
-rw-r--r--compiler/rustc_mir_transform/src/generator.rs5
-rw-r--r--compiler/rustc_parse/src/parser/path.rs37
-rw-r--r--compiler/rustc_resolve/src/diagnostics.rs170
-rw-r--r--compiler/rustc_resolve/src/late.rs28
-rw-r--r--compiler/rustc_resolve/src/late/diagnostics.rs38
-rw-r--r--compiler/rustc_resolve/src/late/lifetimes.rs3
-rw-r--r--compiler/rustc_resolve/src/lib.rs21
-rw-r--r--compiler/rustc_resolve/src/macros.rs2
-rw-r--r--compiler/rustc_session/src/options.rs2
-rw-r--r--compiler/rustc_session/src/session.rs24
-rw-r--r--compiler/rustc_target/src/spec/mod.rs3
-rw-r--r--compiler/rustc_trait_selection/src/autoderef.rs10
-rw-r--r--compiler/rustc_trait_selection/src/opaque_types.rs7
-rw-r--r--compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs8
-rw-r--r--compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs10
-rw-r--r--compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs1
-rw-r--r--compiler/rustc_trait_selection/src/traits/select/confirmation.rs4
-rw-r--r--compiler/rustc_trait_selection/src/traits/select/mod.rs14
-rw-r--r--compiler/rustc_typeck/src/astconv/generics.rs23
-rw-r--r--compiler/rustc_typeck/src/check/callee.rs1
-rw-r--r--compiler/rustc_typeck/src/check/check.rs3
-rw-r--r--compiler/rustc_typeck/src/check/closure.rs38
-rw-r--r--compiler/rustc_typeck/src/check/coercion.rs5
-rw-r--r--compiler/rustc_typeck/src/check/demand.rs1
-rw-r--r--compiler/rustc_typeck/src/check/expr.rs7
-rw-r--r--compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs66
-rw-r--r--compiler/rustc_typeck/src/check/method/suggest.rs10
-rw-r--r--compiler/rustc_typeck/src/check/place_op.rs57
-rw-r--r--compiler/rustc_typeck/src/check/upvar.rs43
-rw-r--r--compiler/rustc_typeck/src/check/writeback.rs42
-rw-r--r--compiler/rustc_typeck/src/expr_use_visitor.rs2
-rw-r--r--compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs6
-rw-r--r--library/core/src/cell.rs10
-rw-r--r--library/core/src/convert/mod.rs8
-rw-r--r--library/core/src/fmt/mod.rs7
-rw-r--r--library/core/src/iter/range.rs10
-rw-r--r--library/core/src/lib.rs2
-rw-r--r--library/core/src/option.rs6
-rw-r--r--library/core/src/result.rs8
-rw-r--r--library/core/src/slice/sort.rs25
-rw-r--r--library/core/tests/convert.rs16
-rw-r--r--library/core/tests/lib.rs4
-rw-r--r--library/std/src/ffi/c_str.rs2
-rw-r--r--library/std/src/lib.rs13
-rw-r--r--library/std/src/process.rs2
-rw-r--r--library/std/src/rt.rs88
-rw-r--r--library/std/src/sync/mutex.rs6
-rw-r--r--library/std/src/sync/rwlock.rs12
-rw-r--r--library/std/src/sys/unix/mod.rs2
-rw-r--r--library/std/src/sys/unix/thread.rs11
-rw-r--r--library/std/src/sys_common/mod.rs2
-rw-r--r--library/std/src/sys_common/rt.rs81
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-rw-r--r--library/std/src/thread/mod.rs12
-rw-r--r--library/test/src/formatters/junit.rs5
-rw-r--r--rustfmt.toml1
-rw-r--r--src/bootstrap/check.rs9
-rw-r--r--src/bootstrap/defaults/config.library.toml3
-rw-r--r--src/bootstrap/setup.rs80
-rwxr-xr-xsrc/ci/scripts/install-clang.sh6
m---------src/doc/book0
m---------src/doc/nomicon0
m---------src/doc/reference0
m---------src/doc/rust-by-example0
m---------src/doc/rustc-dev-guide0
-rw-r--r--src/doc/rustc/src/codegen-options/index.md4
-rw-r--r--src/librustdoc/clean/mod.rs4
-rw-r--r--src/librustdoc/clean/simplify.rs10
-rw-r--r--src/librustdoc/clean/types.rs3
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-rw-r--r--src/test/mir-opt/const_promotion_extern_static.BAR-promoted[0].SimplifyCfg-elaborate-drops.after.mir6
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-rw-r--r--src/tools/clippy/tests/ui/excessive_precision.fixed10
-rw-r--r--src/tools/clippy/tests/ui/excessive_precision.stderr32
-rw-r--r--src/tools/clippy/tests/ui/explicit_deref_methods.fixed2
-rw-r--r--src/tools/clippy/tests/ui/explicit_deref_methods.rs2
-rw-r--r--src/tools/clippy/tests/ui/fallible_impl_from.rs1
-rw-r--r--src/tools/clippy/tests/ui/fallible_impl_from.stderr16
-rw-r--r--src/tools/clippy/tests/ui/float_cmp.rs3
-rw-r--r--src/tools/clippy/tests/ui/float_cmp.stderr12
-rw-r--r--src/tools/clippy/tests/ui/for_loop_fixable.fixed2
-rw-r--r--src/tools/clippy/tests/ui/for_loop_fixable.rs2
-rw-r--r--src/tools/clippy/tests/ui/if_let_some_result.fixed28
-rw-r--r--src/tools/clippy/tests/ui/if_let_some_result.rs28
-rw-r--r--src/tools/clippy/tests/ui/if_then_panic.fixed34
-rw-r--r--src/tools/clippy/tests/ui/if_then_panic.rs38
-rw-r--r--src/tools/clippy/tests/ui/if_then_panic.stderr20
-rw-r--r--src/tools/clippy/tests/ui/infinite_loop.rs1
-rw-r--r--src/tools/clippy/tests/ui/infinite_loop.stderr22
-rw-r--r--src/tools/clippy/tests/ui/inherent_to_string.rs1
-rw-r--r--src/tools/clippy/tests/ui/inherent_to_string.stderr4
-rw-r--r--src/tools/clippy/tests/ui/iter_not_returning_iterator.rs47
-rw-r--r--src/tools/clippy/tests/ui/iter_not_returning_iterator.stderr16
-rw-r--r--src/tools/clippy/tests/ui/logic_bug.rs2
-rw-r--r--src/tools/clippy/tests/ui/manual_split_once.fixed6
-rw-r--r--src/tools/clippy/tests/ui/manual_split_once.rs6
-rw-r--r--src/tools/clippy/tests/ui/manual_split_once.stderr28
-rw-r--r--src/tools/clippy/tests/ui/many_single_char_names.rs2
-rw-r--r--src/tools/clippy/tests/ui/map_flatten.fixed1
-rw-r--r--src/tools/clippy/tests/ui/map_flatten.rs1
-rw-r--r--src/tools/clippy/tests/ui/map_flatten.stderr14
-rw-r--r--src/tools/clippy/tests/ui/match_result_ok.fixed63
-rw-r--r--src/tools/clippy/tests/ui/match_result_ok.rs63
-rw-r--r--src/tools/clippy/tests/ui/match_result_ok.stderr (renamed from src/tools/clippy/tests/ui/if_let_some_result.stderr)19
-rw-r--r--src/tools/clippy/tests/ui/match_single_binding.fixed2
-rw-r--r--src/tools/clippy/tests/ui/match_single_binding.rs2
-rw-r--r--src/tools/clippy/tests/ui/mut_key.rs34
-rw-r--r--src/tools/clippy/tests/ui/mut_key.stderr88
-rw-r--r--src/tools/clippy/tests/ui/needless_borrow.fixed24
-rw-r--r--src/tools/clippy/tests/ui/needless_borrow.rs24
-rw-r--r--src/tools/clippy/tests/ui/needless_borrow.stderr14
-rw-r--r--src/tools/clippy/tests/ui/needless_pass_by_value.rs1
-rw-r--r--src/tools/clippy/tests/ui/needless_pass_by_value.stderr52
-rw-r--r--src/tools/clippy/tests/ui/needless_return.fixed12
-rw-r--r--src/tools/clippy/tests/ui/needless_return.rs12
-rw-r--r--src/tools/clippy/tests/ui/needless_return.stderr64
-rw-r--r--src/tools/clippy/tests/ui/nonminimal_bool.rs2
-rw-r--r--src/tools/clippy/tests/ui/nonminimal_bool_methods.rs2
-rw-r--r--src/tools/clippy/tests/ui/op_ref.rs1
-rw-r--r--src/tools/clippy/tests/ui/op_ref.stderr4
-rw-r--r--src/tools/clippy/tests/ui/overflow_check_conditional.rs1
-rw-r--r--src/tools/clippy/tests/ui/overflow_check_conditional.stderr16
-rw-r--r--src/tools/clippy/tests/ui/ptr_arg.rs7
-rw-r--r--src/tools/clippy/tests/ui/ptr_arg.stderr24
-rw-r--r--src/tools/clippy/tests/ui/repeat_once.fixed2
-rw-r--r--src/tools/clippy/tests/ui/repeat_once.rs2
-rw-r--r--src/tools/clippy/tests/ui/same_name_method.rs111
-rw-r--r--src/tools/clippy/tests/ui/same_name_method.stderr64
-rw-r--r--src/tools/clippy/tests/ui/semicolon_if_nothing_returned.rs5
-rw-r--r--src/tools/clippy/tests/ui/semicolon_if_nothing_returned.stderr12
-rw-r--r--src/tools/clippy/tests/ui/suspicious_else_formatting.rs9
-rw-r--r--src/tools/clippy/tests/ui/suspicious_else_formatting.stderr18
-rw-r--r--src/tools/clippy/tests/ui/trivially_copy_pass_by_ref.rs6
-rw-r--r--src/tools/clippy/tests/ui/trivially_copy_pass_by_ref.stderr34
-rw-r--r--src/tools/clippy/tests/ui/while_let_on_iterator.fixed18
-rw-r--r--src/tools/clippy/tests/ui/while_let_on_iterator.stderr18
-rw-r--r--src/tools/clippy/tests/ui/wrong_self_convention2.rs37
m---------src/tools/rust-analyzer33
-rw-r--r--src/tools/tidy/src/deps.rs1
-rw-r--r--src/tools/tidy/src/lib.rs1
640 files changed, 19509 insertions, 3575 deletions
diff --git a/Cargo.lock b/Cargo.lock
index 6b3a714920b..a4e1ab6c1e4 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1660,7 +1660,7 @@ checksum = "3ca8957e71f04a205cb162508f9326aea04676c8dfd0711220190d6b83664f3f"
 dependencies = [
  "bitmaps",
  "rand_core 0.5.1",
- "rand_xoshiro",
+ "rand_xoshiro 0.4.0",
  "sized-chunks",
  "typenum",
  "version_check",
@@ -2256,7 +2256,7 @@ dependencies = [
  "libc",
  "log",
  "measureme",
- "rand 0.8.3",
+ "rand 0.8.4",
  "rustc-workspace-hack",
  "rustc_version",
  "shell-escape",
@@ -2852,9 +2852,9 @@ dependencies = [
 
 [[package]]
 name = "rand"
-version = "0.8.3"
+version = "0.8.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0ef9e7e66b4468674bfcb0c81af8b7fa0bb154fa9f28eb840da5c447baeb8d7e"
+checksum = "2e7573632e6454cf6b99d7aac4ccca54be06da05aca2ef7423d22d27d4d4bcd8"
 dependencies = [
  "libc",
  "rand_chacha 0.3.0",
@@ -2946,6 +2946,15 @@ dependencies = [
 ]
 
 [[package]]
+name = "rand_xoshiro"
+version = "0.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6f97cdb2a36ed4183de61b2f824cc45c9f1037f28afe0a322e9fff4c108b5aaa"
+dependencies = [
+ "rand_core 0.6.2",
+]
+
+[[package]]
 name = "rayon"
 version = "1.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -3706,6 +3715,7 @@ dependencies = [
  "rustc_incremental",
  "rustc_index",
  "rustc_macros",
+ "rustc_metadata",
  "rustc_middle",
  "rustc_serialize",
  "rustc_session",
@@ -4086,6 +4096,8 @@ dependencies = [
  "either",
  "gsgdt",
  "polonius-engine",
+ "rand 0.8.4",
+ "rand_xoshiro 0.6.0",
  "rustc-rayon-core",
  "rustc_apfloat",
  "rustc_arena",
@@ -5096,7 +5108,7 @@ checksum = "dac1c663cfc93810f88aed9b8941d48cabf856a1b111c29a40439018d870eb22"
 dependencies = [
  "cfg-if 1.0.0",
  "libc",
- "rand 0.8.3",
+ "rand 0.8.4",
  "redox_syscall",
  "remove_dir_all",
  "winapi",
diff --git a/Cargo.toml b/Cargo.toml
index 3822da2ccd5..ce7073886c2 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -41,6 +41,7 @@ members = [
 exclude = [
   "build",
   "compiler/rustc_codegen_cranelift",
+  "compiler/rustc_codegen_gcc",
   "src/test/rustdoc-gui",
   # HACK(eddyb) This hardcodes the fact that our CI uses `/checkout/obj`.
   "obj",
diff --git a/compiler/rustc_ast_lowering/src/item.rs b/compiler/rustc_ast_lowering/src/item.rs
index 9f879494d73..ea9eb0cf274 100644
--- a/compiler/rustc_ast_lowering/src/item.rs
+++ b/compiler/rustc_ast_lowering/src/item.rs
@@ -1328,32 +1328,45 @@ impl<'hir> LoweringContext<'_, 'hir> {
         // keep track of the Span info. Now, `add_implicitly_sized` in `AstConv` checks both param bounds and
         // where clauses for `?Sized`.
         for pred in &generics.where_clause.predicates {
-            if let WherePredicate::BoundPredicate(ref bound_pred) = *pred {
-                'next_bound: for bound in &bound_pred.bounds {
-                    if let GenericBound::Trait(_, TraitBoundModifier::Maybe) = *bound {
-                        // Check if the where clause type is a plain type parameter.
-                        match self
-                            .resolver
-                            .get_partial_res(bound_pred.bounded_ty.id)
-                            .map(|d| (d.base_res(), d.unresolved_segments()))
-                        {
-                            Some((Res::Def(DefKind::TyParam, def_id), 0))
-                                if bound_pred.bound_generic_params.is_empty() =>
-                            {
-                                for param in &generics.params {
-                                    if def_id == self.resolver.local_def_id(param.id).to_def_id() {
-                                        continue 'next_bound;
-                                    }
-                                }
-                            }
-                            _ => {}
-                        }
-                        self.diagnostic().span_err(
-                            bound_pred.bounded_ty.span,
-                            "`?Trait` bounds are only permitted at the \
-                                 point where a type parameter is declared",
-                        );
+            let bound_pred = match *pred {
+                WherePredicate::BoundPredicate(ref bound_pred) => bound_pred,
+                _ => continue,
+            };
+            let compute_is_param = || {
+                // Check if the where clause type is a plain type parameter.
+                match self
+                    .resolver
+                    .get_partial_res(bound_pred.bounded_ty.id)
+                    .map(|d| (d.base_res(), d.unresolved_segments()))
+                {
+                    Some((Res::Def(DefKind::TyParam, def_id), 0))
+                        if bound_pred.bound_generic_params.is_empty() =>
+                    {
+                        generics
+                            .params
+                            .iter()
+                            .find(|p| def_id == self.resolver.local_def_id(p.id).to_def_id())
+                            .is_some()
                     }
+                    // Either the `bounded_ty` is not a plain type parameter, or
+                    // it's not found in the generic type parameters list.
+                    _ => false,
+                }
+            };
+            // We only need to compute this once per `WherePredicate`, but don't
+            // need to compute this at all unless there is a Maybe bound.
+            let mut is_param: Option<bool> = None;
+            for bound in &bound_pred.bounds {
+                if !matches!(*bound, GenericBound::Trait(_, TraitBoundModifier::Maybe)) {
+                    continue;
+                }
+                let is_param = *is_param.get_or_insert_with(compute_is_param);
+                if !is_param {
+                    self.diagnostic().span_err(
+                        bound.span(),
+                        "`?Trait` bounds are only permitted at the \
+                        point where a type parameter is declared",
+                    );
                 }
             }
         }
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index 3c75089a760..245199e3751 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -166,7 +166,7 @@ pub trait ResolverAstLowering {
     fn legacy_const_generic_args(&mut self, expr: &Expr) -> Option<Vec<usize>>;
 
     /// Obtains resolution for a `NodeId` with a single resolution.
-    fn get_partial_res(&mut self, id: NodeId) -> Option<PartialRes>;
+    fn get_partial_res(&self, id: NodeId) -> Option<PartialRes>;
 
     /// Obtains per-namespace resolutions for `use` statement with the given `NodeId`.
     fn get_import_res(&mut self, id: NodeId) -> PerNS<Option<Res<NodeId>>>;
diff --git a/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs b/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs
index 366ade1a713..15309ccd8df 100644
--- a/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs
@@ -327,6 +327,7 @@ impl TypeOpInfo<'tcx> for AscribeUserTypeQuery<'tcx> {
     }
 }
 
+#[instrument(skip(fulfill_cx, infcx), level = "debug")]
 fn try_extract_error_from_fulfill_cx<'tcx>(
     mut fulfill_cx: Box<dyn TraitEngine<'tcx> + 'tcx>,
     infcx: &InferCtxt<'_, 'tcx>,
@@ -341,7 +342,7 @@ fn try_extract_error_from_fulfill_cx<'tcx>(
     let _errors = fulfill_cx.select_all_or_error(infcx).err().unwrap_or_else(Vec::new);
 
     let (sub_region, cause) = infcx.with_region_constraints(|region_constraints| {
-        debug!(?region_constraints);
+        debug!("{:#?}", region_constraints);
         region_constraints.constraints.iter().find_map(|(constraint, cause)| {
             match *constraint {
                 Constraint::RegSubReg(sub, sup) if sup == placeholder_region && sup != sub => {
@@ -356,7 +357,7 @@ fn try_extract_error_from_fulfill_cx<'tcx>(
         })
     })?;
 
-    debug!(?sub_region, ?cause);
+    debug!(?sub_region, "cause = {:#?}", cause);
     let nice_error = match (error_region, sub_region) {
         (Some(error_region), &ty::ReVar(vid)) => NiceRegionError::new(
             infcx,
diff --git a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
index f4cbbb60b05..37398894a20 100644
--- a/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
+++ b/compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs
@@ -10,8 +10,7 @@ use rustc_middle::mir::{
     ProjectionElem, Rvalue, Statement, StatementKind, Terminator, TerminatorKind, VarBindingForm,
 };
 use rustc_middle::ty::{self, suggest_constraining_type_param, Ty};
-use rustc_mir_dataflow::drop_flag_effects;
-use rustc_mir_dataflow::move_paths::{MoveOutIndex, MovePathIndex};
+use rustc_mir_dataflow::move_paths::{InitKind, MoveOutIndex, MovePathIndex};
 use rustc_span::source_map::DesugaringKind;
 use rustc_span::symbol::sym;
 use rustc_span::{BytePos, MultiSpan, Span, DUMMY_SP};
@@ -1531,25 +1530,45 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             }
         }
 
+        let mut mpis = vec![mpi];
+        let move_paths = &self.move_data.move_paths;
+        mpis.extend(move_paths[mpi].parents(move_paths).map(|(mpi, _)| mpi));
+
         let mut stack = Vec::new();
-        stack.extend(predecessor_locations(self.body, location).map(|predecessor| {
-            let is_back_edge = location.dominates(predecessor, &self.dominators);
-            (predecessor, is_back_edge)
-        }));
+        let mut back_edge_stack = Vec::new();
+
+        predecessor_locations(self.body, location).for_each(|predecessor| {
+            if location.dominates(predecessor, &self.dominators) {
+                back_edge_stack.push(predecessor)
+            } else {
+                stack.push(predecessor);
+            }
+        });
+
+        let mut reached_start = false;
+
+        /* Check if the mpi is initialized as an argument */
+        let mut is_argument = false;
+        for arg in self.body.args_iter() {
+            let path = self.move_data.rev_lookup.find_local(arg);
+            if mpis.contains(&path) {
+                is_argument = true;
+            }
+        }
 
         let mut visited = FxHashSet::default();
         let mut move_locations = FxHashSet::default();
         let mut reinits = vec![];
         let mut result = vec![];
 
-        'dfs: while let Some((location, is_back_edge)) = stack.pop() {
+        let mut dfs_iter = |result: &mut Vec<MoveSite>, location: Location, is_back_edge: bool| {
             debug!(
                 "report_use_of_moved_or_uninitialized: (current_location={:?}, back_edge={})",
                 location, is_back_edge
             );
 
             if !visited.insert(location) {
-                continue;
+                return true;
             }
 
             // check for moves
@@ -1568,10 +1587,6 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                 // worry about the other case: that is, if there is a move of a.b.c, it is already
                 // marked as a move of a.b and a as well, so we will generate the correct errors
                 // there.
-                let mut mpis = vec![mpi];
-                let move_paths = &self.move_data.move_paths;
-                mpis.extend(move_paths[mpi].parents(move_paths).map(|(mpi, _)| mpi));
-
                 for moi in &self.move_data.loc_map[location] {
                     debug!("report_use_of_moved_or_uninitialized: moi={:?}", moi);
                     let path = self.move_data.moves[*moi].path;
@@ -1599,33 +1614,70 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                         // Because we stop the DFS here, we only highlight `let c = a`,
                         // and not `let b = a`. We will of course also report an error at
                         // `let c = a` which highlights `let b = a` as the move.
-                        continue 'dfs;
+                        return true;
                     }
                 }
             }
 
             // check for inits
             let mut any_match = false;
-            drop_flag_effects::for_location_inits(
-                self.infcx.tcx,
-                &self.body,
-                self.move_data,
-                location,
-                |m| {
-                    if m == mpi {
-                        any_match = true;
+            for ii in &self.move_data.init_loc_map[location] {
+                let init = self.move_data.inits[*ii];
+                match init.kind {
+                    InitKind::Deep | InitKind::NonPanicPathOnly => {
+                        if mpis.contains(&init.path) {
+                            any_match = true;
+                        }
                     }
-                },
-            );
+                    InitKind::Shallow => {
+                        if mpi == init.path {
+                            any_match = true;
+                        }
+                    }
+                }
+            }
             if any_match {
                 reinits.push(location);
-                continue 'dfs;
+                return true;
             }
+            return false;
+        };
 
-            stack.extend(predecessor_locations(self.body, location).map(|predecessor| {
-                let back_edge = location.dominates(predecessor, &self.dominators);
-                (predecessor, is_back_edge || back_edge)
-            }));
+        while let Some(location) = stack.pop() {
+            if dfs_iter(&mut result, location, false) {
+                continue;
+            }
+
+            let mut has_predecessor = false;
+            predecessor_locations(self.body, location).for_each(|predecessor| {
+                if location.dominates(predecessor, &self.dominators) {
+                    back_edge_stack.push(predecessor)
+                } else {
+                    stack.push(predecessor);
+                }
+                has_predecessor = true;
+            });
+
+            if !has_predecessor {
+                reached_start = true;
+            }
+        }
+        if (is_argument || !reached_start) && result.is_empty() {
+            /* Process back edges (moves in future loop iterations) only if
+               the move path is definitely initialized upon loop entry,
+               to avoid spurious "in previous iteration" errors.
+               During DFS, if there's a path from the error back to the start
+               of the function with no intervening init or move, then the
+               move path may be uninitialized at loop entry.
+            */
+            while let Some(location) = back_edge_stack.pop() {
+                if dfs_iter(&mut result, location, true) {
+                    continue;
+                }
+
+                predecessor_locations(self.body, location)
+                    .for_each(|predecessor| back_edge_stack.push(predecessor));
+            }
         }
 
         // Check if we can reach these reinits from a move location.
diff --git a/compiler/rustc_borrowck/src/lib.rs b/compiler/rustc_borrowck/src/lib.rs
index 72f4907a09f..6ffa0095e4b 100644
--- a/compiler/rustc_borrowck/src/lib.rs
+++ b/compiler/rustc_borrowck/src/lib.rs
@@ -144,6 +144,7 @@ fn mir_borrowck<'tcx>(
 /// If `return_body_with_facts` is true, then return the body with non-erased
 /// region ids on which the borrow checking was performed together with Polonius
 /// facts.
+#[instrument(skip(infcx, input_body, input_promoted), level = "debug")]
 fn do_mir_borrowck<'a, 'tcx>(
     infcx: &InferCtxt<'a, 'tcx>,
     input_body: &Body<'tcx>,
@@ -152,7 +153,7 @@ fn do_mir_borrowck<'a, 'tcx>(
 ) -> (BorrowCheckResult<'tcx>, Option<Box<BodyWithBorrowckFacts<'tcx>>>) {
     let def = input_body.source.with_opt_param().as_local().unwrap();
 
-    debug!("do_mir_borrowck(def = {:?})", def);
+    debug!(?def);
 
     let tcx = infcx.tcx;
     let param_env = tcx.param_env(def.did);
diff --git a/compiler/rustc_borrowck/src/nll.rs b/compiler/rustc_borrowck/src/nll.rs
index 477b049b075..e5924f9d084 100644
--- a/compiler/rustc_borrowck/src/nll.rs
+++ b/compiler/rustc_borrowck/src/nll.rs
@@ -54,6 +54,7 @@ crate struct NllOutput<'tcx> {
 /// Rewrites the regions in the MIR to use NLL variables, also scraping out the set of universal
 /// regions (e.g., region parameters) declared on the function. That set will need to be given to
 /// `compute_regions`.
+#[instrument(skip(infcx, param_env, body, promoted), level = "debug")]
 pub(crate) fn replace_regions_in_mir<'cx, 'tcx>(
     infcx: &InferCtxt<'cx, 'tcx>,
     param_env: ty::ParamEnv<'tcx>,
@@ -62,7 +63,7 @@ pub(crate) fn replace_regions_in_mir<'cx, 'tcx>(
 ) -> UniversalRegions<'tcx> {
     let def = body.source.with_opt_param().as_local().unwrap();
 
-    debug!("replace_regions_in_mir(def={:?})", def);
+    debug!(?def);
 
     // Compute named region information. This also renumbers the inputs/outputs.
     let universal_regions = UniversalRegions::new(infcx, def, param_env);
diff --git a/compiler/rustc_borrowck/src/region_infer/mod.rs b/compiler/rustc_borrowck/src/region_infer/mod.rs
index 917d69a5c86..65d6e3a4ae5 100644
--- a/compiler/rustc_borrowck/src/region_infer/mod.rs
+++ b/compiler/rustc_borrowck/src/region_infer/mod.rs
@@ -552,6 +552,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     /// Performs region inference and report errors if we see any
     /// unsatisfiable constraints. If this is a closure, returns the
     /// region requirements to propagate to our creator, if any.
+    #[instrument(skip(self, infcx, body, polonius_output), level = "debug")]
     pub(super) fn solve(
         &mut self,
         infcx: &InferCtxt<'_, 'tcx>,
@@ -607,10 +608,9 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     /// for each region variable until all the constraints are
     /// satisfied. Note that some values may grow **too** large to be
     /// feasible, but we check this later.
+    #[instrument(skip(self, _body), level = "debug")]
     fn propagate_constraints(&mut self, _body: &Body<'tcx>) {
-        debug!("propagate_constraints()");
-
-        debug!("propagate_constraints: constraints={:#?}", {
+        debug!("constraints={:#?}", {
             let mut constraints: Vec<_> = self.constraints.outlives().iter().collect();
             constraints.sort();
             constraints
@@ -637,12 +637,13 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     /// computed, by unioning the values of its successors.
     /// Assumes that all successors have been computed already
     /// (which is assured by iterating over SCCs in dependency order).
+    #[instrument(skip(self), level = "debug")]
     fn compute_value_for_scc(&mut self, scc_a: ConstraintSccIndex) {
         let constraint_sccs = self.constraint_sccs.clone();
 
         // Walk each SCC `B` such that `A: B`...
         for &scc_b in constraint_sccs.successors(scc_a) {
-            debug!("propagate_constraint_sccs: scc_a = {:?} scc_b = {:?}", scc_a, scc_b);
+            debug!(?scc_b);
 
             // ...and add elements from `B` into `A`. One complication
             // arises because of universes: If `B` contains something
@@ -663,11 +664,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             self.apply_member_constraint(scc_a, m_c_i, member_constraints.choice_regions(m_c_i));
         }
 
-        debug!(
-            "propagate_constraint_sccs: scc_a = {:?} has value {:?}",
-            scc_a,
-            self.scc_values.region_value_str(scc_a),
-        );
+        debug!(value = ?self.scc_values.region_value_str(scc_a));
     }
 
     /// Invoked for each `R0 member of [R1..Rn]` constraint.
@@ -681,14 +678,13 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     /// is considered a *lower bound*.  If possible, we will modify
     /// the constraint to set it equal to one of the option regions.
     /// If we make any changes, returns true, else false.
+    #[instrument(skip(self, member_constraint_index), level = "debug")]
     fn apply_member_constraint(
         &mut self,
         scc: ConstraintSccIndex,
         member_constraint_index: NllMemberConstraintIndex,
         choice_regions: &[ty::RegionVid],
     ) -> bool {
-        debug!("apply_member_constraint(scc={:?}, choice_regions={:#?})", scc, choice_regions,);
-
         // Create a mutable vector of the options. We'll try to winnow
         // them down.
         let mut choice_regions: Vec<ty::RegionVid> = choice_regions.to_vec();
@@ -714,7 +710,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                 .universal_regions_outlived_by(scc)
                 .all(|lb| self.universal_region_relations.outlives(o_r, lb))
         });
-        debug!("apply_member_constraint: after lb, choice_regions={:?}", choice_regions);
+        debug!(?choice_regions, "after lb");
 
         // Now find all the *upper bounds* -- that is, each UB is a
         // free region that must outlive the member region `R0` (`UB:
@@ -723,10 +719,10 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         let rev_scc_graph = self.reverse_scc_graph();
         let universal_region_relations = &self.universal_region_relations;
         for ub in rev_scc_graph.upper_bounds(scc) {
-            debug!("apply_member_constraint: ub={:?}", ub);
+            debug!(?ub);
             choice_regions.retain(|&o_r| universal_region_relations.outlives(ub, o_r));
         }
-        debug!("apply_member_constraint: after ub, choice_regions={:?}", choice_regions);
+        debug!(?choice_regions, "after ub");
 
         // If we ruled everything out, we're done.
         if choice_regions.is_empty() {
@@ -735,7 +731,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
 
         // Otherwise, we need to find the minimum remaining choice, if
         // any, and take that.
-        debug!("apply_member_constraint: choice_regions remaining are {:#?}", choice_regions);
+        debug!("choice_regions remaining are {:#?}", choice_regions);
         let min = |r1: ty::RegionVid, r2: ty::RegionVid| -> Option<ty::RegionVid> {
             let r1_outlives_r2 = self.universal_region_relations.outlives(r1, r2);
             let r2_outlives_r1 = self.universal_region_relations.outlives(r2, r1);
@@ -748,27 +744,18 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         };
         let mut min_choice = choice_regions[0];
         for &other_option in &choice_regions[1..] {
-            debug!(
-                "apply_member_constraint: min_choice={:?} other_option={:?}",
-                min_choice, other_option,
-            );
+            debug!(?min_choice, ?other_option,);
             match min(min_choice, other_option) {
                 Some(m) => min_choice = m,
                 None => {
-                    debug!(
-                        "apply_member_constraint: {:?} and {:?} are incomparable; no min choice",
-                        min_choice, other_option,
-                    );
+                    debug!(?min_choice, ?other_option, "incomparable; no min choice",);
                     return false;
                 }
             }
         }
 
         let min_choice_scc = self.constraint_sccs.scc(min_choice);
-        debug!(
-            "apply_member_constraint: min_choice={:?} best_choice_scc={:?}",
-            min_choice, min_choice_scc,
-        );
+        debug!(?min_choice, ?min_choice_scc);
         if self.scc_values.add_region(scc, min_choice_scc) {
             self.member_constraints_applied.push(AppliedMemberConstraint {
                 member_region_scc: scc,
@@ -1091,8 +1078,9 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     ///   include the CFG anyhow.
     /// - For each `end('x)` element in `'r`, compute the mutual LUB, yielding
     ///   a result `'y`.
+    #[instrument(skip(self), level = "debug")]
     pub(crate) fn universal_upper_bound(&self, r: RegionVid) -> RegionVid {
-        debug!("universal_upper_bound(r={:?}={})", r, self.region_value_str(r));
+        debug!(r = %self.region_value_str(r));
 
         // Find the smallest universal region that contains all other
         // universal regions within `region`.
@@ -1102,7 +1090,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             lub = self.universal_region_relations.postdom_upper_bound(lub, ur);
         }
 
-        debug!("universal_upper_bound: r={:?} lub={:?}", r, lub);
+        debug!(?lub);
 
         lub
     }
@@ -1262,9 +1250,8 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     }
 
     // Evaluate whether `sup_region: sub_region`.
+    #[instrument(skip(self), level = "debug")]
     fn eval_outlives(&self, sup_region: RegionVid, sub_region: RegionVid) -> bool {
-        debug!("eval_outlives({:?}: {:?})", sup_region, sub_region);
-
         debug!(
             "eval_outlives: sup_region's value = {:?} universal={:?}",
             self.region_value_str(sup_region),
@@ -1467,6 +1454,10 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     ///
     /// Things that are to be propagated are accumulated into the
     /// `outlives_requirements` vector.
+    #[instrument(
+        skip(self, body, propagated_outlives_requirements, errors_buffer),
+        level = "debug"
+    )]
     fn check_universal_region(
         &self,
         body: &Body<'tcx>,
@@ -1474,8 +1465,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         propagated_outlives_requirements: &mut Option<&mut Vec<ClosureOutlivesRequirement<'tcx>>>,
         errors_buffer: &mut RegionErrors<'tcx>,
     ) {
-        debug!("check_universal_region(fr={:?})", longer_fr);
-
         let longer_fr_scc = self.constraint_sccs.scc(longer_fr);
 
         // Because this free region must be in the ROOT universe, we
@@ -1880,21 +1869,13 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     }
 
     /// Finds some region R such that `fr1: R` and `R` is live at `elem`.
+    #[instrument(skip(self), level = "trace")]
     crate fn find_sub_region_live_at(&self, fr1: RegionVid, elem: Location) -> RegionVid {
-        debug!("find_sub_region_live_at(fr1={:?}, elem={:?})", fr1, elem);
-        debug!("find_sub_region_live_at: {:?} is in scc {:?}", fr1, self.constraint_sccs.scc(fr1));
-        debug!(
-            "find_sub_region_live_at: {:?} is in universe {:?}",
-            fr1,
-            self.scc_universes[self.constraint_sccs.scc(fr1)]
-        );
+        trace!(scc = ?self.constraint_sccs.scc(fr1));
+        trace!(universe = ?self.scc_universes[self.constraint_sccs.scc(fr1)]);
         self.find_constraint_paths_between_regions(fr1, |r| {
             // First look for some `r` such that `fr1: r` and `r` is live at `elem`
-            debug!(
-                "find_sub_region_live_at: liveness_constraints for {:?} are {:?}",
-                r,
-                self.liveness_constraints.region_value_str(r),
-            );
+            trace!(?r, liveness_constraints=?self.liveness_constraints.region_value_str(r));
             self.liveness_constraints.contains(r, elem)
         })
         .or_else(|| {
diff --git a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
index b35e76b96ad..4eb7be542e7 100644
--- a/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
+++ b/compiler/rustc_borrowck/src/region_infer/opaque_types.rs
@@ -124,7 +124,22 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             ty::ReVar(vid) => {
                 // Find something that we can name
                 let upper_bound = self.approx_universal_upper_bound(vid);
-                self.definitions[upper_bound].external_name.unwrap_or(region)
+                let upper_bound = &self.definitions[upper_bound];
+                match upper_bound.external_name {
+                    Some(reg) => reg,
+                    None => {
+                        // Nothing exact found, so we pick the first one that we find.
+                        let scc = self.constraint_sccs.scc(vid);
+                        for vid in self.rev_scc_graph.as_ref().unwrap().upper_bounds(scc) {
+                            match self.definitions[vid].external_name {
+                                None => {}
+                                Some(&ty::ReStatic) => {}
+                                Some(region) => return region,
+                            }
+                        }
+                        region
+                    }
+                }
             }
             _ => region,
         })
diff --git a/compiler/rustc_borrowck/src/renumber.rs b/compiler/rustc_borrowck/src/renumber.rs
index 9377473befe..20567610f65 100644
--- a/compiler/rustc_borrowck/src/renumber.rs
+++ b/compiler/rustc_borrowck/src/renumber.rs
@@ -7,13 +7,13 @@ use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable};
 
 /// Replaces all free regions appearing in the MIR with fresh
 /// inference variables, returning the number of variables created.
+#[instrument(skip(infcx, body, promoted), level = "debug")]
 pub fn renumber_mir<'tcx>(
     infcx: &InferCtxt<'_, 'tcx>,
     body: &mut Body<'tcx>,
     promoted: &mut IndexVec<Promoted, Body<'tcx>>,
 ) {
-    debug!("renumber_mir()");
-    debug!("renumber_mir: body.arg_count={:?}", body.arg_count);
+    debug!(?body.arg_count);
 
     let mut visitor = NllVisitor { infcx };
 
@@ -26,12 +26,11 @@ pub fn renumber_mir<'tcx>(
 
 /// Replaces all regions appearing in `value` with fresh inference
 /// variables.
+#[instrument(skip(infcx), level = "debug")]
 pub fn renumber_regions<'tcx, T>(infcx: &InferCtxt<'_, 'tcx>, value: T) -> T
 where
     T: TypeFoldable<'tcx>,
 {
-    debug!("renumber_regions(value={:?})", value);
-
     infcx.tcx.fold_regions(value, &mut false, |_region, _depth| {
         let origin = NllRegionVariableOrigin::Existential { from_forall: false };
         infcx.next_nll_region_var(origin)
@@ -56,12 +55,11 @@ impl<'a, 'tcx> MutVisitor<'tcx> for NllVisitor<'a, 'tcx> {
         self.infcx.tcx
     }
 
+    #[instrument(skip(self), level = "debug")]
     fn visit_ty(&mut self, ty: &mut Ty<'tcx>, ty_context: TyContext) {
-        debug!("visit_ty(ty={:?}, ty_context={:?})", ty, ty_context);
-
         *ty = self.renumber_regions(ty);
 
-        debug!("visit_ty: ty={:?}", ty);
+        debug!(?ty);
     }
 
     fn process_projection_elem(
@@ -80,21 +78,19 @@ impl<'a, 'tcx> MutVisitor<'tcx> for NllVisitor<'a, 'tcx> {
         None
     }
 
+    #[instrument(skip(self), level = "debug")]
     fn visit_substs(&mut self, substs: &mut SubstsRef<'tcx>, location: Location) {
-        debug!("visit_substs(substs={:?}, location={:?})", substs, location);
-
         *substs = self.renumber_regions(*substs);
 
-        debug!("visit_substs: substs={:?}", substs);
+        debug!(?substs);
     }
 
+    #[instrument(skip(self), level = "debug")]
     fn visit_region(&mut self, region: &mut ty::Region<'tcx>, location: Location) {
-        debug!("visit_region(region={:?}, location={:?})", region, location);
-
         let old_region = *region;
         *region = self.renumber_regions(&old_region);
 
-        debug!("visit_region: region={:?}", region);
+        debug!(?region);
     }
 
     fn visit_const(&mut self, constant: &mut &'tcx ty::Const<'tcx>, _location: Location) {
diff --git a/compiler/rustc_borrowck/src/type_check/canonical.rs b/compiler/rustc_borrowck/src/type_check/canonical.rs
index df28fb6e28e..7d4df59902a 100644
--- a/compiler/rustc_borrowck/src/type_check/canonical.rs
+++ b/compiler/rustc_borrowck/src/type_check/canonical.rs
@@ -24,6 +24,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
     /// **Any `rustc_infer::infer` operations that might generate region
     /// constraints should occur within this method so that those
     /// constraints can be properly localized!**
+    #[instrument(skip(self, category, op), level = "trace")]
     pub(super) fn fully_perform_op<R, Op>(
         &mut self,
         locations: Locations,
@@ -131,14 +132,13 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         }
     }
 
+    #[instrument(skip(self), level = "debug")]
     pub(super) fn prove_predicate(
         &mut self,
         predicate: ty::Predicate<'tcx>,
         locations: Locations,
         category: ConstraintCategory,
     ) {
-        debug!("prove_predicate(predicate={:?}, location={:?})", predicate, locations,);
-
         let param_env = self.param_env;
         self.fully_perform_op(
             locations,
@@ -150,11 +150,11 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         })
     }
 
+    #[instrument(skip(self), level = "debug")]
     pub(super) fn normalize<T>(&mut self, value: T, location: impl NormalizeLocation) -> T
     where
         T: type_op::normalize::Normalizable<'tcx> + fmt::Display + Copy + 'tcx,
     {
-        debug!("normalize(value={:?}, location={:?})", value, location);
         let param_env = self.param_env;
         self.fully_perform_op(
             location.to_locations(),
diff --git a/compiler/rustc_borrowck/src/type_check/constraint_conversion.rs b/compiler/rustc_borrowck/src/type_check/constraint_conversion.rs
index b0207468485..ab1a7461b4b 100644
--- a/compiler/rustc_borrowck/src/type_check/constraint_conversion.rs
+++ b/compiler/rustc_borrowck/src/type_check/constraint_conversion.rs
@@ -53,9 +53,8 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
         }
     }
 
+    #[instrument(skip(self), level = "debug")]
     pub(super) fn convert_all(&mut self, query_constraints: &QueryRegionConstraints<'tcx>) {
-        debug!("convert_all(query_constraints={:#?})", query_constraints);
-
         let QueryRegionConstraints { outlives, member_constraints } = query_constraints;
 
         // Annoying: to invoke `self.to_region_vid`, we need access to
diff --git a/compiler/rustc_borrowck/src/type_check/input_output.rs b/compiler/rustc_borrowck/src/type_check/input_output.rs
index 46d30a188ed..24332690bec 100644
--- a/compiler/rustc_borrowck/src/type_check/input_output.rs
+++ b/compiler/rustc_borrowck/src/type_check/input_output.rs
@@ -20,6 +20,7 @@ use crate::universal_regions::UniversalRegions;
 use super::{Locations, TypeChecker};
 
 impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
+    #[instrument(skip(self, body, universal_regions), level = "debug")]
     pub(super) fn equate_inputs_and_outputs(
         &mut self,
         body: &Body<'tcx>,
@@ -64,10 +65,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             );
         }
 
-        debug!(
-            "equate_inputs_and_outputs: normalized_input_tys = {:?}, local_decls = {:?}",
-            normalized_input_tys, body.local_decls
-        );
+        debug!(?normalized_input_tys, ?body.local_decls);
 
         // Equate expected input tys with those in the MIR.
         for (argument_index, &normalized_input_ty) in normalized_input_tys.iter().enumerate() {
@@ -160,9 +158,8 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         }
     }
 
+    #[instrument(skip(self, span), level = "debug")]
     fn equate_normalized_input_or_output(&mut self, a: Ty<'tcx>, b: Ty<'tcx>, span: Span) {
-        debug!("equate_normalized_input_or_output(a={:?}, b={:?})", a, b);
-
         if let Err(_) =
             self.eq_types(a, b, Locations::All(span), ConstraintCategory::BoringNoLocation)
         {
diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs
index 4bbeed39e45..55790bd2daa 100644
--- a/compiler/rustc_borrowck/src/type_check/mod.rs
+++ b/compiler/rustc_borrowck/src/type_check/mod.rs
@@ -197,6 +197,11 @@ pub(crate) fn type_check<'mir, 'tcx>(
                 .into_iter()
                 .filter_map(|(opaque_type_key, mut decl)| {
                     decl.concrete_ty = infcx.resolve_vars_if_possible(decl.concrete_ty);
+                    trace!(
+                        "finalized opaque type {:?} to {:#?}",
+                        opaque_type_key,
+                        decl.concrete_ty.kind()
+                    );
                     if decl.concrete_ty.has_infer_types_or_consts() {
                         infcx.tcx.sess.delay_span_bug(
                             body.span,
@@ -247,6 +252,18 @@ pub(crate) fn type_check<'mir, 'tcx>(
     MirTypeckResults { constraints, universal_region_relations, opaque_type_values }
 }
 
+#[instrument(
+    skip(
+        infcx,
+        body,
+        promoted,
+        region_bound_pairs,
+        borrowck_context,
+        universal_region_relations,
+        extra
+    ),
+    level = "debug"
+)]
 fn type_check_internal<'a, 'tcx, R>(
     infcx: &'a InferCtxt<'a, 'tcx>,
     param_env: ty::ParamEnv<'tcx>,
@@ -1114,13 +1131,14 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         }
     }
 
+    #[instrument(skip(self, data), level = "debug")]
     fn push_region_constraints(
         &mut self,
         locations: Locations,
         category: ConstraintCategory,
         data: &QueryRegionConstraints<'tcx>,
     ) {
-        debug!("push_region_constraints: constraints generated at {:?} are {:#?}", locations, data);
+        debug!("constraints generated: {:#?}", data);
 
         constraint_conversion::ConstraintConversion::new(
             self.infcx,
@@ -1180,6 +1198,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         self.relate_types(expected, ty::Variance::Invariant, found, locations, category)
     }
 
+    #[instrument(skip(self), level = "debug")]
     fn relate_type_and_user_type(
         &mut self,
         a: Ty<'tcx>,
@@ -1188,11 +1207,6 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         locations: Locations,
         category: ConstraintCategory,
     ) -> Fallible<()> {
-        debug!(
-            "relate_type_and_user_type(a={:?}, v={:?}, user_ty={:?}, locations={:?})",
-            a, v, user_ty, locations,
-        );
-
         let annotated_type = self.user_type_annotations[user_ty.base].inferred_ty;
         let mut curr_projected_ty = PlaceTy::from_ty(annotated_type);
 
@@ -1250,6 +1264,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
     ///   generics of `foo`). Note that `anon_ty` is not just the opaque type,
     ///   but the entire return type (which may contain opaque types within it).
     /// * `revealed_ty` would be `Box<(T, u32)>`
+    #[instrument(skip(self), level = "debug")]
     fn eq_opaque_type_and_type(
         &mut self,
         revealed_ty: Ty<'tcx>,
@@ -1257,13 +1272,6 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         locations: Locations,
         category: ConstraintCategory,
     ) -> Fallible<()> {
-        debug!(
-            "eq_opaque_type_and_type( \
-             revealed_ty={:?}, \
-             anon_ty={:?})",
-            revealed_ty, anon_ty
-        );
-
         // Fast path for the common case.
         if !anon_ty.has_opaque_types() {
             if let Err(terr) = self.eq_types(anon_ty, revealed_ty, locations, category) {
@@ -1283,7 +1291,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         let body = self.body;
         let mir_def_id = body.source.def_id().expect_local();
 
-        debug!("eq_opaque_type_and_type: mir_def_id={:?}", mir_def_id);
+        debug!(?mir_def_id);
         self.fully_perform_op(
             locations,
             category,
@@ -1305,12 +1313,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                         anon_ty,
                         locations.span(body),
                     ));
-                    debug!(
-                        "eq_opaque_type_and_type: \
-                         instantiated output_ty={:?} \
-                         revealed_ty={:?}",
-                        output_ty, revealed_ty
-                    );
+                    debug!(?output_ty, ?revealed_ty);
 
                     // Make sure that the inferred types are well-formed. I'm
                     // not entirely sure this is needed (the HIR type check
@@ -1328,7 +1331,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                             .eq(output_ty, revealed_ty)?,
                     );
 
-                    debug!("eq_opaque_type_and_type: equated");
+                    debug!("equated");
 
                     Ok(InferOk { value: (), obligations: obligations.into_vec() })
                 },
@@ -1368,8 +1371,8 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         self.infcx.tcx
     }
 
+    #[instrument(skip(self, body, location), level = "debug")]
     fn check_stmt(&mut self, body: &Body<'tcx>, stmt: &Statement<'tcx>, location: Location) {
-        debug!("check_stmt: {:?}", stmt);
         let tcx = self.tcx();
         match stmt.kind {
             StatementKind::Assign(box (ref place, ref rv)) => {
@@ -1522,13 +1525,13 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         }
     }
 
+    #[instrument(skip(self, body, term_location), level = "debug")]
     fn check_terminator(
         &mut self,
         body: &Body<'tcx>,
         term: &Terminator<'tcx>,
         term_location: Location,
     ) {
-        debug!("check_terminator: {:?}", term);
         let tcx = self.tcx();
         match term.kind {
             TerminatorKind::Goto { .. }
@@ -2685,9 +2688,10 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         tcx.predicates_of(def_id).instantiate(tcx, substs)
     }
 
+    #[instrument(skip(self, body), level = "debug")]
     fn typeck_mir(&mut self, body: &Body<'tcx>) {
         self.last_span = body.span;
-        debug!("run_on_mir: {:?}", body.span);
+        debug!(?body.span);
 
         for (local, local_decl) in body.local_decls.iter_enumerated() {
             self.check_local(&body, local, local_decl);
diff --git a/compiler/rustc_borrowck/src/type_check/relate_tys.rs b/compiler/rustc_borrowck/src/type_check/relate_tys.rs
index de86d39cc37..b788529dc1c 100644
--- a/compiler/rustc_borrowck/src/type_check/relate_tys.rs
+++ b/compiler/rustc_borrowck/src/type_check/relate_tys.rs
@@ -17,6 +17,7 @@ use crate::type_check::{BorrowCheckContext, Locations};
 ///
 /// N.B., the type `a` is permitted to have unresolved inference
 /// variables, but not the type `b`.
+#[instrument(skip(infcx, param_env, borrowck_context), level = "debug")]
 pub(super) fn relate_types<'tcx>(
     infcx: &InferCtxt<'_, 'tcx>,
     param_env: ty::ParamEnv<'tcx>,
@@ -27,7 +28,6 @@ pub(super) fn relate_types<'tcx>(
     category: ConstraintCategory,
     borrowck_context: &mut BorrowCheckContext<'_, 'tcx>,
 ) -> Fallible<()> {
-    debug!("relate_types(a={:?}, v={:?}, b={:?}, locations={:?})", a, v, b, locations);
     TypeRelating::new(
         infcx,
         NllTypeRelatingDelegate::new(
diff --git a/compiler/rustc_codegen_cranelift/scripts/filter_profile.rs b/compiler/rustc_codegen_cranelift/scripts/filter_profile.rs
index 7a51293f5cd..a0e99267c2b 100755
--- a/compiler/rustc_codegen_cranelift/scripts/filter_profile.rs
+++ b/compiler/rustc_codegen_cranelift/scripts/filter_profile.rs
@@ -96,7 +96,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
             stack = &stack[..index + REPORT_SYMBOL_NAMES.len()];
         }
 
-        const ENCODE_METADATA: &str = "rustc_middle::ty::context::TyCtxt::encode_metadata";
+        const ENCODE_METADATA: &str = "rustc_metadata::rmeta::encoder::encode_metadata";
         if let Some(index) = stack.find(ENCODE_METADATA) {
             stack = &stack[..index + ENCODE_METADATA.len()];
         }
diff --git a/compiler/rustc_codegen_cranelift/src/driver/aot.rs b/compiler/rustc_codegen_cranelift/src/driver/aot.rs
index 40cbc5e1a7e..32cc50eebe4 100644
--- a/compiler/rustc_codegen_cranelift/src/driver/aot.rs
+++ b/compiler/rustc_codegen_cranelift/src/driver/aot.rs
@@ -6,8 +6,8 @@ use std::path::PathBuf;
 use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
 use rustc_codegen_ssa::{CodegenResults, CompiledModule, CrateInfo, ModuleKind};
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
+use rustc_metadata::EncodedMetadata;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
-use rustc_middle::middle::cstore::EncodedMetadata;
 use rustc_middle::mir::mono::{CodegenUnit, MonoItem};
 use rustc_session::cgu_reuse_tracker::CguReuse;
 use rustc_session::config::{DebugInfo, OutputType};
diff --git a/compiler/rustc_codegen_cranelift/src/lib.rs b/compiler/rustc_codegen_cranelift/src/lib.rs
index 2ceccdd3499..beb97edf09e 100644
--- a/compiler/rustc_codegen_cranelift/src/lib.rs
+++ b/compiler/rustc_codegen_cranelift/src/lib.rs
@@ -30,8 +30,8 @@ use std::any::Any;
 use rustc_codegen_ssa::traits::CodegenBackend;
 use rustc_codegen_ssa::CodegenResults;
 use rustc_errors::ErrorReported;
+use rustc_metadata::EncodedMetadata;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
-use rustc_middle::middle::cstore::EncodedMetadata;
 use rustc_session::config::OutputFilenames;
 use rustc_session::Session;
 
diff --git a/compiler/rustc_codegen_cranelift/src/metadata.rs b/compiler/rustc_codegen_cranelift/src/metadata.rs
index 9afa999a87d..1c8fd0b01d9 100644
--- a/compiler/rustc_codegen_cranelift/src/metadata.rs
+++ b/compiler/rustc_codegen_cranelift/src/metadata.rs
@@ -3,16 +3,20 @@
 use object::write::{Object, StandardSegment, Symbol, SymbolSection};
 use object::{SectionKind, SymbolFlags, SymbolKind, SymbolScope};
 
-use rustc_middle::middle::cstore::EncodedMetadata;
+use rustc_metadata::EncodedMetadata;
 use rustc_middle::ty::TyCtxt;
 
 // Adapted from https://github.com/rust-lang/rust/blob/da573206f87b5510de4b0ee1a9c044127e409bd3/src/librustc_codegen_llvm/base.rs#L47-L112
-pub(crate) fn new_metadata_object(tcx: TyCtxt<'_>, cgu_name: &str, metadata: &EncodedMetadata) -> Vec<u8> {
+pub(crate) fn new_metadata_object(
+    tcx: TyCtxt<'_>,
+    cgu_name: &str,
+    metadata: &EncodedMetadata,
+) -> Vec<u8> {
     use snap::write::FrameEncoder;
     use std::io::Write;
 
     let mut compressed = rustc_metadata::METADATA_HEADER.to_vec();
-    FrameEncoder::new(&mut compressed).write_all(&metadata.raw_data).unwrap();
+    FrameEncoder::new(&mut compressed).write_all(metadata.raw_data()).unwrap();
 
     let triple = crate::target_triple(tcx.sess);
 
diff --git a/compiler/rustc_codegen_gcc/.github/workflows/main.yml b/compiler/rustc_codegen_gcc/.github/workflows/main.yml
new file mode 100644
index 00000000000..98bed8ef387
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/.github/workflows/main.yml
@@ -0,0 +1,96 @@
+name: CI
+
+on:
+  - push
+  - pull_request
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    strategy:
+      fail-fast: false
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Install packages
+      run: sudo apt-get install ninja-build ripgrep
+
+    - name: Download artifact
+      uses: dawidd6/action-download-artifact@v2
+      with:
+          workflow: main.yml
+          name: libgccjit.so
+          path: gcc-build
+          repo: antoyo/gcc
+
+    - name: Setup path to libgccjit
+      run: |
+          echo $(readlink -f gcc-build) > gcc_path
+          ln gcc-build/libgccjit.so gcc-build/libgccjit.so.0
+
+    - name: Set LIBRARY_PATH
+      run: |
+        echo "LIBRARY_PATH=$(cat gcc_path)" >> $GITHUB_ENV
+        echo "LD_LIBRARY_PATH=$(cat gcc_path)" >> $GITHUB_ENV
+
+    # https://github.com/actions/cache/issues/133
+    - name: Fixup owner of ~/.cargo/
+      # Don't remove the trailing /. It is necessary to follow the symlink.
+      run: sudo chown -R $(whoami):$(id -ng) ~/.cargo/
+
+    - name: Cache cargo installed crates
+      uses: actions/cache@v1.1.2
+      with:
+        path: ~/.cargo/bin
+        key: cargo-installed-crates2-ubuntu-latest
+
+    - name: Cache cargo registry
+      uses: actions/cache@v1
+      with:
+        path: ~/.cargo/registry
+        key: ${{ runner.os }}-cargo-registry2-${{ hashFiles('**/Cargo.lock') }}
+
+    - name: Cache cargo index
+      uses: actions/cache@v1
+      with:
+        path: ~/.cargo/git
+        key: ${{ runner.os }}-cargo-index-${{ hashFiles('**/Cargo.lock') }}
+
+    - name: Cache cargo target dir
+      uses: actions/cache@v1.1.2
+      with:
+        path: target
+        key: ${{ runner.os }}-cargo-build-target-${{ hashFiles('rust-toolchain') }}
+
+    - name: Build
+      run: |
+        ./prepare_build.sh
+        ./build.sh
+        cargo test
+        ./clean_all.sh
+
+    - name: Prepare dependencies
+      run: |
+        git config --global user.email "user@example.com"
+        git config --global user.name "User"
+        ./prepare.sh
+
+    # Compile is a separate step, as the actions-rs/cargo action supports error annotations
+    - name: Compile
+      uses: actions-rs/cargo@v1.0.3
+      with:
+        command: build
+        args: --release
+
+    - name: Test
+      run: |
+        # Enable backtraces for easier debugging
+        export RUST_BACKTRACE=1
+
+        # Reduce amount of benchmark runs as they are slow
+        export COMPILE_RUNS=2
+        export RUN_RUNS=2
+
+        ./test.sh --release
diff --git a/compiler/rustc_codegen_gcc/.gitignore b/compiler/rustc_codegen_gcc/.gitignore
new file mode 100644
index 00000000000..1e2f9e3aebb
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/.gitignore
@@ -0,0 +1,20 @@
+target
+**/*.rs.bk
+*.rlib
+*.o
+perf.data
+perf.data.old
+*.events
+*.string*
+/build_sysroot/sysroot
+/build_sysroot/sysroot_src
+/build_sysroot/Cargo.lock
+/build_sysroot/test_target/Cargo.lock
+/rust
+/simple-raytracer
+/regex
+gimple*
+*asm
+res
+test-backend
+gcc_path
diff --git a/compiler/rustc_codegen_gcc/Cargo.lock b/compiler/rustc_codegen_gcc/Cargo.lock
new file mode 100644
index 00000000000..60a2101c689
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/Cargo.lock
@@ -0,0 +1,373 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
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+ "memchr",
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+
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+dependencies = [
+ "regex",
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+
+[[package]]
+name = "gccjit"
+version = "1.0.0"
+source = "git+https://github.com/antoyo/gccjit.rs#2d4fea7319f80531b2e5d264fca9f1c498a3a62e"
+dependencies = [
+ "gccjit_sys",
+]
+
+[[package]]
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+source = "git+https://github.com/antoyo/gccjit.rs#2d4fea7319f80531b2e5d264fca9f1c498a3a62e"
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+ "cfg-if",
+ "libc 0.2.102",
+ "wasi",
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+checksum = "ab5ef0d4909ef3724cc8cce6ccc8572c5c817592e9285f5464f8e86f8bd3726e"
+
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+checksum = "62b467343b94ba476dcb2500d242dadbb39557df889310ac77c5d99100aaac33"
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+ "libc 0.2.102",
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+checksum = "bc633605454125dec4b66843673f01c7df2b89479b32e0ed634e43a91cff62a5"
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+ "getopts",
+ "libc 0.2.102",
+ "num_cpus",
+ "termcolor",
+ "threadpool",
+ "wait-timeout",
+ "walkdir",
+]
+
+[[package]]
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+checksum = "e32a70cf75e5846d53a673923498228bbec6a8624708a9ea5645f075d6276122"
+
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+ "ar",
+ "gccjit",
+ "lang_tester",
+ "object",
+ "target-lexicon",
+ "tempfile",
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+name = "winapi"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5c839a674fcd7a98952e593242ea400abe93992746761e38641405d28b00f419"
+dependencies = [
+ "winapi-i686-pc-windows-gnu",
+ "winapi-x86_64-pc-windows-gnu",
+]
+
+[[package]]
+name = "winapi-i686-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
+
+[[package]]
+name = "winapi-util"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "70ec6ce85bb158151cae5e5c87f95a8e97d2c0c4b001223f33a334e3ce5de178"
+dependencies = [
+ "winapi",
+]
+
+[[package]]
+name = "winapi-x86_64-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
diff --git a/compiler/rustc_codegen_gcc/Cargo.toml b/compiler/rustc_codegen_gcc/Cargo.toml
new file mode 100644
index 00000000000..9e8c195c15f
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/Cargo.toml
@@ -0,0 +1,51 @@
+[package]
+name = "rustc_codegen_gcc"
+version = "0.1.0"
+authors = ["Antoni Boucher <bouanto@zoho.com>"]
+edition = "2018"
+license = "MIT OR Apache-2.0"
+
+[lib]
+crate-type = ["dylib"]
+
+[[test]]
+name = "lang_tests"
+path = "tests/lib.rs"
+harness = false
+
+[dependencies]
+gccjit = { git = "https://github.com/antoyo/gccjit.rs" }
+
+# Local copy.
+#gccjit = { path = "../gccjit.rs" }
+
+target-lexicon = "0.10.0"
+
+ar = "0.8.0"
+
+[dependencies.object]
+version = "0.25.0"
+default-features = false
+features = ["read", "std", "write"] # We don't need WASM support.
+
+[dev-dependencies]
+lang_tester = "0.3.9"
+tempfile = "3.1.0"
+
+[profile.dev]
+# By compiling dependencies with optimizations, performing tests gets much faster.
+opt-level = 3
+
+[profile.dev.package.rustc_codegen_gcc]
+# Disabling optimizations for cg_gccjit itself makes compilation after a change faster.
+opt-level = 0
+
+# Disable optimizations and debuginfo of build scripts and some of the heavy build deps, as the
+# execution time of build scripts is so fast that optimizing them slows down the total build time.
+[profile.dev.build-override]
+opt-level = 0
+debug = false
+
+[profile.release.build-override]
+opt-level = 0
+debug = false
diff --git a/compiler/rustc_codegen_gcc/LICENSE-APACHE b/compiler/rustc_codegen_gcc/LICENSE-APACHE
new file mode 100644
index 00000000000..1b5ec8b78e2
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/LICENSE-APACHE
@@ -0,0 +1,176 @@
+                              Apache License
+                        Version 2.0, January 2004
+                     http://www.apache.org/licenses/
+
+TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+1. Definitions.
+
+   "License" shall mean the terms and conditions for use, reproduction,
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+   outstanding shares, or (iii) beneficial ownership of such entity.
+
+   "You" (or "Your") shall mean an individual or Legal Entity
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+5. Submission of Contributions. Unless You explicitly state otherwise,
+   any Contribution intentionally submitted for inclusion in the Work
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+   Notwithstanding the above, nothing herein shall supersede or modify
+   the terms of any separate license agreement you may have executed
+   with Licensor regarding such Contributions.
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+6. Trademarks. This License does not grant permission to use the trade
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+8. Limitation of Liability. In no event and under no legal theory,
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+
+END OF TERMS AND CONDITIONS
diff --git a/compiler/rustc_codegen_gcc/LICENSE-MIT b/compiler/rustc_codegen_gcc/LICENSE-MIT
new file mode 100644
index 00000000000..31aa79387f2
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/LICENSE-MIT
@@ -0,0 +1,23 @@
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software
+is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
diff --git a/compiler/rustc_codegen_gcc/Readme.md b/compiler/rustc_codegen_gcc/Readme.md
new file mode 100644
index 00000000000..709d93c6edb
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/Readme.md
@@ -0,0 +1,135 @@
+# WIP libgccjit codegen backend for rust
+
+This is a GCC codegen for rustc, which means it can be loaded by the existing rustc frontend, but benefits from GCC: more architectures are supported and GCC's optimizations are used.
+
+**Despite its name, libgccjit can be used for ahead-of-time compilation, as is used here.**
+
+## Motivation
+
+The primary goal of this project is to be able to compile Rust code on platforms unsupported by LLVM.
+A secondary goal is to check if using the gcc backend will provide any run-time speed improvement for the programs compiled using rustc.
+
+## Building
+
+**This requires a patched libgccjit in order to work.
+The patches in [this repostory](https://github.com/antoyo/libgccjit-patches) need to be applied.
+(Those patches should work when applied on master, but in case it doesn't work, they are known to work when applied on 079c23cfe079f203d5df83fea8e92a60c7d7e878.)
+You can also use my [fork of gcc](https://github.com/antoyo/gcc) which already includes these patches.**
+
+**Put the path to your custom build of libgccjit in the file `gcc_path`.**
+
+```bash
+$ git clone https://github.com/rust-lang/rustc_codegen_gcc.git
+$ cd rustc_codegen_gcc
+$ ./prepare_build.sh # download and patch sysroot src
+$ ./build.sh --release
+```
+
+To run the tests:
+
+```bash
+$ ./prepare.sh # download and patch sysroot src and install hyperfine for benchmarking
+$ ./test.sh --release
+```
+
+## Usage
+
+`$cg_gccjit_dir` is the directory you cloned this repo into in the following instructions.
+
+### Cargo
+
+```bash
+$ CHANNEL="release" $cg_gccjit_dir/cargo.sh run
+```
+
+If you compiled cg_gccjit in debug mode (aka you didn't pass `--release` to `./test.sh`) you should use `CHANNEL="debug"` instead or omit `CHANNEL="release"` completely.
+
+### Rustc
+
+> You should prefer using the Cargo method.
+
+```bash
+$ rustc +$(cat $cg_gccjit_dir/rust-toolchain) -Cpanic=abort -Zcodegen-backend=$cg_gccjit_dir/target/release/librustc_codegen_gcc.so --sysroot $cg_gccjit_dir/build_sysroot/sysroot my_crate.rs
+```
+
+## Env vars
+
+<dl>
+    <dt>CG_GCCJIT_INCR_CACHE_DISABLED</dt>
+    <dd>Don't cache object files in the incremental cache. Useful during development of cg_gccjit
+    to make it possible to use incremental mode for all analyses performed by rustc without caching
+    object files when their content should have been changed by a change to cg_gccjit.</dd>
+    <dt>CG_GCCJIT_DISPLAY_CG_TIME</dt>
+    <dd>Display the time it took to perform codegen for a crate</dd>
+</dl>
+
+## Debugging
+
+Sometimes, libgccjit will crash and output an error like this:
+
+```
+during RTL pass: expand
+libgccjit.so: error: in expmed_mode_index, at expmed.h:249
+0x7f0da2e61a35 expmed_mode_index
+	../../../gcc/gcc/expmed.h:249
+0x7f0da2e61aa4 expmed_op_cost_ptr
+	../../../gcc/gcc/expmed.h:271
+0x7f0da2e620dc sdiv_cost_ptr
+	../../../gcc/gcc/expmed.h:540
+0x7f0da2e62129 sdiv_cost
+	../../../gcc/gcc/expmed.h:558
+0x7f0da2e73c12 expand_divmod(int, tree_code, machine_mode, rtx_def*, rtx_def*, rtx_def*, int)
+	../../../gcc/gcc/expmed.c:4335
+0x7f0da2ea1423 expand_expr_real_2(separate_ops*, rtx_def*, machine_mode, expand_modifier)
+	../../../gcc/gcc/expr.c:9240
+0x7f0da2cd1a1e expand_gimple_stmt_1
+	../../../gcc/gcc/cfgexpand.c:3796
+0x7f0da2cd1c30 expand_gimple_stmt
+	../../../gcc/gcc/cfgexpand.c:3857
+0x7f0da2cd90a9 expand_gimple_basic_block
+	../../../gcc/gcc/cfgexpand.c:5898
+0x7f0da2cdade8 execute
+	../../../gcc/gcc/cfgexpand.c:6582
+```
+
+To see the code which causes this error, call the following function:
+
+```c
+gcc_jit_context_dump_to_file(ctxt, "/tmp/output.c", 1 /* update_locations */)
+```
+
+This will create a C-like file and add the locations into the IR pointing to this C file.
+Then, rerun the program and it will output the location in the second line:
+
+```
+libgccjit.so: /tmp/something.c:61322:0: error: in expmed_mode_index, at expmed.h:249
+```
+
+Or add a breakpoint to `add_error` in gdb and print the line number using:
+
+```
+p loc->m_line
+```
+
+### How to use a custom-build rustc
+
+ * Build the stage2 compiler (`rustup toolchain link debug-current build/x86_64-unknown-linux-gnu/stage2`).
+ * Clean and rebuild the codegen with `debug-current` in the file `rust-toolchain`.
+
+### How to build a cross-compiling libgccjit
+
+#### Building libgccjit
+
+ * Follow these instructions: https://preshing.com/20141119/how-to-build-a-gcc-cross-compiler/ with the following changes:
+ * Configure gcc with `../gcc/configure --enable-host-shared --disable-multilib --enable-languages=c,jit,c++ --disable-bootstrap --enable-checking=release --prefix=/opt/m68k-gcc/ --target=m68k-linux --without-headers`.
+ * Some shells, like fish, don't define the environment variable `$MACHTYPE`.
+ * Add `CFLAGS="-Wno-error=attributes -g -O2"` at the end of the configure command for building glibc (`CFLAGS="-Wno-error=attributes -Wno-error=array-parameter -Wno-error=stringop-overflow -Wno-error=array-bounds -g -O2"` for glibc 2.31, which is useful for Debian).
+
+#### Configuring rustc_codegen_gcc
+
+ * Set `TARGET_TRIPLE="m68k-unknown-linux-gnu"` in config.sh.
+ * Since rustc doesn't support this architecture yet, set it back to `TARGET_TRIPLE="mips-unknown-linux-gnu"` (or another target having the same attributes). Alternatively, create a [target specification file](https://book.avr-rust.com/005.1-the-target-specification-json-file.html) (note that the `arch` specified in this file must be supported by the rust compiler).
+ * Set `linker='-Clinker=m68k-linux-gcc'`.
+ * Set the path to the cross-compiling libgccjit in `gcc_path`.
+ * Disable the 128-bit integer types if the target doesn't support them by using `let i128_type = context.new_type::<i64>();` in `context.rs` (same for u128_type).
+ * (might not be necessary) Disable the compilation of libstd.so (and possibly libcore.so?).
diff --git a/compiler/rustc_codegen_gcc/build.sh b/compiler/rustc_codegen_gcc/build.sh
new file mode 100755
index 00000000000..17a0d2ab3f0
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/build.sh
@@ -0,0 +1,31 @@
+#!/bin/bash
+
+#set -x
+set -e
+
+if [ -f ./gcc_path ]; then 
+    export GCC_PATH=$(cat gcc_path)
+else
+    echo 'Please put the path to your custom build of libgccjit in the file `gcc_path`, see Readme.md for details'
+    exit 1
+fi
+
+export LD_LIBRARY_PATH="$GCC_PATH"
+export LIBRARY_PATH="$GCC_PATH"
+
+if [[ "$1" == "--release" ]]; then
+    export CHANNEL='release'
+    CARGO_INCREMENTAL=1 cargo rustc --release
+else
+    echo $LD_LIBRARY_PATH
+    export CHANNEL='debug'
+    cargo rustc
+fi
+
+source config.sh
+
+rm -r target/out || true
+mkdir -p target/out/gccjit
+
+echo "[BUILD] sysroot"
+time ./build_sysroot/build_sysroot.sh $CHANNEL
diff --git a/compiler/rustc_codegen_gcc/build_sysroot/Cargo.toml b/compiler/rustc_codegen_gcc/build_sysroot/Cargo.toml
new file mode 100644
index 00000000000..cfadf47cc3f
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/build_sysroot/Cargo.toml
@@ -0,0 +1,19 @@
+[package]
+authors = ["bjorn3 <bjorn3@users.noreply.github.com>"]
+name = "sysroot"
+version = "0.0.0"
+
+[dependencies]
+core = { path = "./sysroot_src/library/core" }
+compiler_builtins = "0.1"
+alloc = { path = "./sysroot_src/library/alloc" }
+std = { path = "./sysroot_src/library/std", features = ["panic_unwind", "backtrace"] }
+test = { path = "./sysroot_src/library/test" }
+
+[patch.crates-io]
+rustc-std-workspace-core = { path = "./sysroot_src/library/rustc-std-workspace-core" }
+rustc-std-workspace-alloc = { path = "./sysroot_src/library/rustc-std-workspace-alloc" }
+rustc-std-workspace-std = { path = "./sysroot_src/library/rustc-std-workspace-std" }
+
+[profile.release]
+debug = true
diff --git a/compiler/rustc_codegen_gcc/build_sysroot/build_sysroot.sh b/compiler/rustc_codegen_gcc/build_sysroot/build_sysroot.sh
new file mode 100755
index 00000000000..d1dcf495db8
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/build_sysroot/build_sysroot.sh
@@ -0,0 +1,30 @@
+#!/bin/bash
+
+# Requires the CHANNEL env var to be set to `debug` or `release.`
+
+set -e
+cd $(dirname "$0")
+
+pushd ../ >/dev/null
+source ./config.sh
+popd >/dev/null
+
+# Cleanup for previous run
+#     v Clean target dir except for build scripts and incremental cache
+rm -r target/*/{debug,release}/{build,deps,examples,libsysroot*,native} 2>/dev/null || true
+rm Cargo.lock test_target/Cargo.lock 2>/dev/null || true
+rm -r sysroot/ 2>/dev/null || true
+
+# Build libs
+export RUSTFLAGS="$RUSTFLAGS -Z force-unstable-if-unmarked -Cpanic=abort"
+if [[ "$1" == "--release" ]]; then
+    sysroot_channel='release'
+    RUSTFLAGS="$RUSTFLAGS -Zmir-opt-level=3" cargo build --target $TARGET_TRIPLE --release
+else
+    sysroot_channel='debug'
+    cargo build --target $TARGET_TRIPLE
+fi
+
+# Copy files to sysroot
+mkdir -p sysroot/lib/rustlib/$TARGET_TRIPLE/lib/
+cp -r target/$TARGET_TRIPLE/$sysroot_channel/deps/* sysroot/lib/rustlib/$TARGET_TRIPLE/lib/
diff --git a/compiler/rustc_codegen_gcc/build_sysroot/prepare_sysroot_src.sh b/compiler/rustc_codegen_gcc/build_sysroot/prepare_sysroot_src.sh
new file mode 100755
index 00000000000..071e7ed1f85
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/build_sysroot/prepare_sysroot_src.sh
@@ -0,0 +1,39 @@
+#!/bin/bash
+set -e
+cd $(dirname "$0")
+
+SRC_DIR=$(dirname $(rustup which rustc))"/../lib/rustlib/src/rust/"
+DST_DIR="sysroot_src"
+
+if [ ! -e $SRC_DIR ]; then
+    echo "Please install rust-src component"
+    exit 1
+fi
+
+rm -rf $DST_DIR
+mkdir -p $DST_DIR/library
+cp -r $SRC_DIR/library $DST_DIR/
+
+pushd $DST_DIR
+echo "[GIT] init"
+git init
+echo "[GIT] add"
+git add .
+echo "[GIT] commit"
+
+# This is needed on systems where nothing is configured.
+# git really needs something here, or it will fail.
+# Even using --author is not enough.
+git config user.email || git config user.email "none@example.com"
+git config user.name || git config user.name "None"
+
+git commit -m "Initial commit" -q
+for file in $(ls ../../patches/ | grep -v patcha); do
+echo "[GIT] apply" $file
+git apply ../../patches/$file
+git add -A
+git commit --no-gpg-sign -m "Patch $file"
+done
+popd
+
+echo "Successfully prepared libcore for building"
diff --git a/compiler/rustc_codegen_gcc/build_sysroot/src/lib.rs b/compiler/rustc_codegen_gcc/build_sysroot/src/lib.rs
new file mode 100644
index 00000000000..0c9ac1ac8e4
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/build_sysroot/src/lib.rs
@@ -0,0 +1 @@
+#![no_std]
diff --git a/compiler/rustc_codegen_gcc/cargo.sh b/compiler/rustc_codegen_gcc/cargo.sh
new file mode 100755
index 00000000000..1001c522052
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/cargo.sh
@@ -0,0 +1,23 @@
+#!/bin/bash
+
+if [ -z $CHANNEL ]; then
+export CHANNEL='debug'
+fi
+
+pushd $(dirname "$0") >/dev/null
+source config.sh
+
+# read nightly compiler from rust-toolchain file
+TOOLCHAIN=$(cat rust-toolchain)
+
+popd >/dev/null
+
+if [[ $(rustc -V) != $(rustc +${TOOLCHAIN} -V) ]]; then
+    echo "rustc_codegen_gcc is build for $(rustc +${TOOLCHAIN} -V) but the default rustc version is $(rustc -V)."
+    echo "Using $(rustc +${TOOLCHAIN} -V)."
+fi
+
+cmd=$1
+shift
+
+RUSTDOCFLAGS="$RUSTFLAGS" cargo +${TOOLCHAIN} $cmd --target $TARGET_TRIPLE $@
diff --git a/compiler/rustc_codegen_gcc/clean_all.sh b/compiler/rustc_codegen_gcc/clean_all.sh
new file mode 100755
index 00000000000..a77d1486fe2
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/clean_all.sh
@@ -0,0 +1,5 @@
+#!/bin/bash --verbose
+set -e
+
+rm -rf target/ build_sysroot/{sysroot/,sysroot_src/,target/,Cargo.lock} perf.data{,.old}
+rm -rf regex/ simple-raytracer/
diff --git a/compiler/rustc_codegen_gcc/config.sh b/compiler/rustc_codegen_gcc/config.sh
new file mode 100644
index 00000000000..87df2f2102b
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/config.sh
@@ -0,0 +1,52 @@
+set -e
+
+export CARGO_INCREMENTAL=0
+
+if [ -f ./gcc_path ]; then 
+    export GCC_PATH=$(cat gcc_path)
+else
+    echo 'Please put the path to your custom build of libgccjit in the file `gcc_path`, see Readme.md for details'
+    exit 1
+fi
+
+unamestr=`uname`
+if [[ "$unamestr" == 'Linux' ]]; then
+   dylib_ext='so'
+elif [[ "$unamestr" == 'Darwin' ]]; then
+   dylib_ext='dylib'
+else
+   echo "Unsupported os"
+   exit 1
+fi
+
+HOST_TRIPLE=$(rustc -vV | grep host | cut -d: -f2 | tr -d " ")
+TARGET_TRIPLE=$HOST_TRIPLE
+#TARGET_TRIPLE="m68k-unknown-linux-gnu"
+
+linker=''
+RUN_WRAPPER=''
+if [[ "$HOST_TRIPLE" != "$TARGET_TRIPLE" ]]; then
+   if [[ "$TARGET_TRIPLE" == "m68k-unknown-linux-gnu" ]]; then
+       TARGET_TRIPLE="mips-unknown-linux-gnu"
+       linker='-Clinker=m68k-linux-gcc'
+   elif [[ "$TARGET_TRIPLE" == "aarch64-unknown-linux-gnu" ]]; then
+      # We are cross-compiling for aarch64. Use the correct linker and run tests in qemu.
+      linker='-Clinker=aarch64-linux-gnu-gcc'
+      RUN_WRAPPER='qemu-aarch64 -L /usr/aarch64-linux-gnu'
+   else
+      echo "Unknown non-native platform"
+   fi
+fi
+
+export RUSTFLAGS="$linker -Cpanic=abort -Zsymbol-mangling-version=v0 -Cdebuginfo=2 -Clto=off -Zpanic-abort-tests -Zcodegen-backend=$(pwd)/target/${CHANNEL:-debug}/librustc_codegen_gcc.$dylib_ext --sysroot $(pwd)/build_sysroot/sysroot"
+
+# FIXME(antoyo): remove once the atomic shim is gone
+if [[ `uname` == 'Darwin' ]]; then
+   export RUSTFLAGS="$RUSTFLAGS -Clink-arg=-undefined -Clink-arg=dynamic_lookup"
+fi
+
+RUSTC="rustc $RUSTFLAGS -L crate=target/out --out-dir target/out"
+export RUSTC_LOG=warn # display metadata load errors
+
+export LD_LIBRARY_PATH="$(pwd)/target/out:$(pwd)/build_sysroot/sysroot/lib/rustlib/$TARGET_TRIPLE/lib:$GCC_PATH"
+export DYLD_LIBRARY_PATH=$LD_LIBRARY_PATH
diff --git a/compiler/rustc_codegen_gcc/example/alloc_example.rs b/compiler/rustc_codegen_gcc/example/alloc_example.rs
new file mode 100644
index 00000000000..bc6dd007ba0
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/example/alloc_example.rs
@@ -0,0 +1,41 @@
+#![feature(start, box_syntax, core_intrinsics, alloc_prelude, alloc_error_handler)]
+#![no_std]
+
+extern crate alloc;
+extern crate alloc_system;
+
+use alloc::prelude::v1::*;
+
+use alloc_system::System;
+
+#[global_allocator]
+static ALLOC: System = System;
+
+#[link(name = "c")]
+extern "C" {
+    fn puts(s: *const u8) -> i32;
+}
+
+#[panic_handler]
+fn panic_handler(_: &core::panic::PanicInfo) -> ! {
+    unsafe {
+        core::intrinsics::abort();
+    }
+}
+
+#[alloc_error_handler]
+fn alloc_error_handler(_: alloc::alloc::Layout) -> ! {
+    unsafe {
+        core::intrinsics::abort();
+    }
+}
+
+#[start]
+fn main(_argc: isize, _argv: *const *const u8) -> isize {
+    let world: Box<&str> = box "Hello World!\0";
+    unsafe {
+        puts(*world as *const str as *const u8);
+    }
+
+    0
+}
diff --git a/compiler/rustc_codegen_gcc/example/alloc_system.rs b/compiler/rustc_codegen_gcc/example/alloc_system.rs
new file mode 100644
index 00000000000..5f66ca67f2d
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/example/alloc_system.rs
@@ -0,0 +1,212 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+#![no_std]
+#![feature(allocator_api, rustc_private)]
+#![cfg_attr(any(unix, target_os = "redox"), feature(libc))]
+
+// The minimum alignment guaranteed by the architecture. This value is used to
+// add fast paths for low alignment values.
+#[cfg(all(any(target_arch = "x86",
+              target_arch = "arm",
+              target_arch = "mips",
+              target_arch = "powerpc",
+              target_arch = "powerpc64")))]
+const MIN_ALIGN: usize = 8;
+#[cfg(all(any(target_arch = "x86_64",
+              target_arch = "aarch64",
+              target_arch = "mips64",
+              target_arch = "s390x",
+              target_arch = "sparc64")))]
+const MIN_ALIGN: usize = 16;
+
+pub struct System;
+#[cfg(any(windows, unix, target_os = "redox"))]
+mod realloc_fallback {
+    use core::alloc::{GlobalAlloc, Layout};
+    use core::cmp;
+    use core::ptr;
+    impl super::System {
+        pub(crate) unsafe fn realloc_fallback(&self, ptr: *mut u8, old_layout: Layout,
+                                              new_size: usize) -> *mut u8 {
+            // Docs for GlobalAlloc::realloc require this to be valid:
+            let new_layout = Layout::from_size_align_unchecked(new_size, old_layout.align());
+            let new_ptr = GlobalAlloc::alloc(self, new_layout);
+            if !new_ptr.is_null() {
+                let size = cmp::min(old_layout.size(), new_size);
+                ptr::copy_nonoverlapping(ptr, new_ptr, size);
+                GlobalAlloc::dealloc(self, ptr, old_layout);
+            }
+            new_ptr
+        }
+    }
+}
+#[cfg(any(unix, target_os = "redox"))]
+mod platform {
+    extern crate libc;
+    use core::ptr;
+    use MIN_ALIGN;
+    use System;
+    use core::alloc::{GlobalAlloc, Layout};
+    unsafe impl GlobalAlloc for System {
+        #[inline]
+        unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+            if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
+                libc::malloc(layout.size()) as *mut u8
+            } else {
+                #[cfg(target_os = "macos")]
+                {
+                    if layout.align() > (1 << 31) {
+                        return ptr::null_mut()
+                    }
+                }
+                aligned_malloc(&layout)
+            }
+        }
+        #[inline]
+        unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
+            if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
+                libc::calloc(layout.size(), 1) as *mut u8
+            } else {
+                let ptr = self.alloc(layout.clone());
+                if !ptr.is_null() {
+                    ptr::write_bytes(ptr, 0, layout.size());
+                }
+                ptr
+            }
+        }
+        #[inline]
+        unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
+            libc::free(ptr as *mut libc::c_void)
+        }
+        #[inline]
+        unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
+            if layout.align() <= MIN_ALIGN && layout.align() <= new_size {
+                libc::realloc(ptr as *mut libc::c_void, new_size) as *mut u8
+            } else {
+                self.realloc_fallback(ptr, layout, new_size)
+            }
+        }
+    }
+    #[cfg(any(target_os = "android",
+              target_os = "hermit",
+              target_os = "redox",
+              target_os = "solaris"))]
+    #[inline]
+    unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
+        // On android we currently target API level 9 which unfortunately
+        // doesn't have the `posix_memalign` API used below. Instead we use
+        // `memalign`, but this unfortunately has the property on some systems
+        // where the memory returned cannot be deallocated by `free`!
+        //
+        // Upon closer inspection, however, this appears to work just fine with
+        // Android, so for this platform we should be fine to call `memalign`
+        // (which is present in API level 9). Some helpful references could
+        // possibly be chromium using memalign [1], attempts at documenting that
+        // memalign + free is ok [2] [3], or the current source of chromium
+        // which still uses memalign on android [4].
+        //
+        // [1]: https://codereview.chromium.org/10796020/
+        // [2]: https://code.google.com/p/android/issues/detail?id=35391
+        // [3]: https://bugs.chromium.org/p/chromium/issues/detail?id=138579
+        // [4]: https://chromium.googlesource.com/chromium/src/base/+/master/
+        //                                       /memory/aligned_memory.cc
+        libc::memalign(layout.align(), layout.size()) as *mut u8
+    }
+    #[cfg(not(any(target_os = "android",
+                  target_os = "hermit",
+                  target_os = "redox",
+                  target_os = "solaris")))]
+    #[inline]
+    unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
+        let mut out = ptr::null_mut();
+        let ret = libc::posix_memalign(&mut out, layout.align(), layout.size());
+        if ret != 0 {
+            ptr::null_mut()
+        } else {
+            out as *mut u8
+        }
+    }
+}
+#[cfg(windows)]
+#[allow(nonstandard_style)]
+mod platform {
+    use MIN_ALIGN;
+    use System;
+    use core::alloc::{GlobalAlloc, Layout};
+    type LPVOID = *mut u8;
+    type HANDLE = LPVOID;
+    type SIZE_T = usize;
+    type DWORD = u32;
+    type BOOL = i32;
+    extern "system" {
+        fn GetProcessHeap() -> HANDLE;
+        fn HeapAlloc(hHeap: HANDLE, dwFlags: DWORD, dwBytes: SIZE_T) -> LPVOID;
+        fn HeapReAlloc(hHeap: HANDLE, dwFlags: DWORD, lpMem: LPVOID, dwBytes: SIZE_T) -> LPVOID;
+        fn HeapFree(hHeap: HANDLE, dwFlags: DWORD, lpMem: LPVOID) -> BOOL;
+        fn GetLastError() -> DWORD;
+    }
+    #[repr(C)]
+    struct Header(*mut u8);
+    const HEAP_ZERO_MEMORY: DWORD = 0x00000008;
+    unsafe fn get_header<'a>(ptr: *mut u8) -> &'a mut Header {
+        &mut *(ptr as *mut Header).offset(-1)
+    }
+    unsafe fn align_ptr(ptr: *mut u8, align: usize) -> *mut u8 {
+        let aligned = ptr.add(align - (ptr as usize & (align - 1)));
+        *get_header(aligned) = Header(ptr);
+        aligned
+    }
+    #[inline]
+    unsafe fn allocate_with_flags(layout: Layout, flags: DWORD) -> *mut u8 {
+        let ptr = if layout.align() <= MIN_ALIGN {
+            HeapAlloc(GetProcessHeap(), flags, layout.size())
+        } else {
+            let size = layout.size() + layout.align();
+            let ptr = HeapAlloc(GetProcessHeap(), flags, size);
+            if ptr.is_null() {
+                ptr
+            } else {
+                align_ptr(ptr, layout.align())
+            }
+        };
+        ptr as *mut u8
+    }
+    unsafe impl GlobalAlloc for System {
+        #[inline]
+        unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+            allocate_with_flags(layout, 0)
+        }
+        #[inline]
+        unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
+            allocate_with_flags(layout, HEAP_ZERO_MEMORY)
+        }
+        #[inline]
+        unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
+            if layout.align() <= MIN_ALIGN {
+                let err = HeapFree(GetProcessHeap(), 0, ptr as LPVOID);
+                debug_assert!(err != 0, "Failed to free heap memory: {}",
+                              GetLastError());
+            } else {
+                let header = get_header(ptr);
+                let err = HeapFree(GetProcessHeap(), 0, header.0 as LPVOID);
+                debug_assert!(err != 0, "Failed to free heap memory: {}",
+                              GetLastError());
+            }
+        }
+        #[inline]
+        unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
+            if layout.align() <= MIN_ALIGN {
+                HeapReAlloc(GetProcessHeap(), 0, ptr as LPVOID, new_size) as *mut u8
+            } else {
+                self.realloc_fallback(ptr, layout, new_size)
+            }
+        }
+    }
+}
diff --git a/compiler/rustc_codegen_gcc/example/arbitrary_self_types_pointers_and_wrappers.rs b/compiler/rustc_codegen_gcc/example/arbitrary_self_types_pointers_and_wrappers.rs
new file mode 100644
index 00000000000..ddeb752f93e
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/example/arbitrary_self_types_pointers_and_wrappers.rs
@@ -0,0 +1,69 @@
+// Adapted from rustc run-pass test suite
+
+#![feature(arbitrary_self_types, unsize, coerce_unsized, dispatch_from_dyn)]
+#![feature(rustc_attrs)]
+
+use std::{
+    ops::{Deref, CoerceUnsized, DispatchFromDyn},
+    marker::Unsize,
+};
+
+struct Ptr<T: ?Sized>(Box<T>);
+
+impl<T: ?Sized> Deref for Ptr<T> {
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        &*self.0
+    }
+}
+
+impl<T: Unsize<U> + ?Sized, U: ?Sized> CoerceUnsized<Ptr<U>> for Ptr<T> {}
+impl<T: Unsize<U> + ?Sized, U: ?Sized> DispatchFromDyn<Ptr<U>> for Ptr<T> {}
+
+struct Wrapper<T: ?Sized>(T);
+
+impl<T: ?Sized> Deref for Wrapper<T> {
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        &self.0
+    }
+}
+
+impl<T: CoerceUnsized<U>, U> CoerceUnsized<Wrapper<U>> for Wrapper<T> {}
+impl<T: DispatchFromDyn<U>, U> DispatchFromDyn<Wrapper<U>> for Wrapper<T> {}
+
+
+trait Trait {
+    // This method isn't object-safe yet. Unsized by-value `self` is object-safe (but not callable
+    // without unsized_locals), but wrappers arond `Self` currently are not.
+    // FIXME (mikeyhew) uncomment this when unsized rvalues object-safety is implemented
+    // fn wrapper(self: Wrapper<Self>) -> i32;
+    fn ptr_wrapper(self: Ptr<Wrapper<Self>>) -> i32;
+    fn wrapper_ptr(self: Wrapper<Ptr<Self>>) -> i32;
+    fn wrapper_ptr_wrapper(self: Wrapper<Ptr<Wrapper<Self>>>) -> i32;
+}
+
+impl Trait for i32 {
+    fn ptr_wrapper(self: Ptr<Wrapper<Self>>) -> i32 {
+        **self
+    }
+    fn wrapper_ptr(self: Wrapper<Ptr<Self>>) -> i32 {
+        **self
+    }
+    fn wrapper_ptr_wrapper(self: Wrapper<Ptr<Wrapper<Self>>>) -> i32 {
+        ***self
+    }
+}
+
+fn main() {
+    let pw = Ptr(Box::new(Wrapper(5))) as Ptr<Wrapper<dyn Trait>>;
+    assert_eq!(pw.ptr_wrapper(), 5);
+
+    let wp = Wrapper(Ptr(Box::new(6))) as Wrapper<Ptr<dyn Trait>>;
+    assert_eq!(wp.wrapper_ptr(), 6);
+
+    let wpw = Wrapper(Ptr(Box::new(Wrapper(7)))) as Wrapper<Ptr<Wrapper<dyn Trait>>>;
+    assert_eq!(wpw.wrapper_ptr_wrapper(), 7);
+}
diff --git a/compiler/rustc_codegen_gcc/example/dst-field-align.rs b/compiler/rustc_codegen_gcc/example/dst-field-align.rs
new file mode 100644
index 00000000000..6c338e99912
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/example/dst-field-align.rs
@@ -0,0 +1,67 @@
+// run-pass
+#![allow(dead_code)]
+struct Foo<T: ?Sized> {
+    a: u16,
+    b: T
+}
+
+trait Bar {
+    fn get(&self) -> usize;
+}
+
+impl Bar for usize {
+    fn get(&self) -> usize { *self }
+}
+
+struct Baz<T: ?Sized> {
+    a: T
+}
+
+struct HasDrop<T: ?Sized> {
+    ptr: Box<usize>,
+    data: T
+}
+
+fn main() {
+    // Test that zero-offset works properly
+    let b : Baz<usize> = Baz { a: 7 };
+    assert_eq!(b.a.get(), 7);
+    let b : &Baz<dyn Bar> = &b;
+    assert_eq!(b.a.get(), 7);
+
+    // Test that the field is aligned properly
+    let f : Foo<usize> = Foo { a: 0, b: 11 };
+    assert_eq!(f.b.get(), 11);
+    let ptr1 : *const u8 = &f.b as *const _ as *const u8;
+
+    let f : &Foo<dyn Bar> = &f;
+    let ptr2 : *const u8 = &f.b as *const _ as *const u8;
+    assert_eq!(f.b.get(), 11);
+
+    // The pointers should be the same
+    assert_eq!(ptr1, ptr2);
+
+    // Test that nested DSTs work properly
+    let f : Foo<Foo<usize>> = Foo { a: 0, b: Foo { a: 1, b: 17 }};
+    assert_eq!(f.b.b.get(), 17);
+    let f : &Foo<Foo<dyn Bar>> = &f;
+    assert_eq!(f.b.b.get(), 17);
+
+    // Test that get the pointer via destructuring works
+
+    let f : Foo<usize> = Foo { a: 0, b: 11 };
+    let f : &Foo<dyn Bar> = &f;
+    let &Foo { a: _, b: ref bar } = f;
+    assert_eq!(bar.get(), 11);
+
+    // Make sure that drop flags don't screw things up
+
+    let d : HasDrop<Baz<[i32; 4]>> = HasDrop {
+        ptr: Box::new(0),
+        data: Baz { a: [1,2,3,4] }
+    };
+    assert_eq!([1,2,3,4], d.data.a);
+
+    let d : &HasDrop<Baz<[i32]>> = &d;
+    assert_eq!(&[1,2,3,4], &d.data.a);
+}
diff --git a/compiler/rustc_codegen_gcc/example/example.rs b/compiler/rustc_codegen_gcc/example/example.rs
new file mode 100644
index 00000000000..5878e8548d9
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/example/example.rs
@@ -0,0 +1,208 @@
+#![feature(no_core, unboxed_closures)]
+#![no_core]
+#![allow(dead_code)]
+
+extern crate mini_core;
+
+use mini_core::*;
+
+fn abc(a: u8) -> u8 {
+    a * 2
+}
+
+fn bcd(b: bool, a: u8) -> u8 {
+    if b {
+        a * 2
+    } else {
+        a * 3
+    }
+}
+
+fn call() {
+    abc(42);
+}
+
+fn indirect_call() {
+    let f: fn() = call;
+    f();
+}
+
+enum BoolOption {
+    Some(bool),
+    None,
+}
+
+fn option_unwrap_or(o: BoolOption, d: bool) -> bool {
+    match o {
+        BoolOption::Some(b) => b,
+        BoolOption::None => d,
+    }
+}
+
+fn ret_42() -> u8 {
+    42
+}
+
+fn return_str() -> &'static str {
+    "hello world"
+}
+
+fn promoted_val() -> &'static u8 {
+    &(1 * 2)
+}
+
+fn cast_ref_to_raw_ptr(abc: &u8) -> *const u8 {
+    abc as *const u8
+}
+
+fn cmp_raw_ptr(a: *const u8, b: *const u8) -> bool {
+    a == b
+}
+
+fn int_cast(a: u16, b: i16) -> (u8, u16, u32, usize, i8, i16, i32, isize, u8, u32) {
+    (
+        a as u8, a as u16, a as u32, a as usize, a as i8, a as i16, a as i32, a as isize, b as u8,
+        b as u32,
+    )
+}
+
+fn char_cast(c: char) -> u8 {
+    c as u8
+}
+
+pub struct DebugTuple(());
+
+fn debug_tuple() -> DebugTuple {
+    DebugTuple(())
+}
+
+fn size_of<T>() -> usize {
+    intrinsics::size_of::<T>()
+}
+
+fn use_size_of() -> usize {
+    size_of::<u64>()
+}
+
+unsafe fn use_copy_intrinsic(src: *const u8, dst: *mut u8) {
+    intrinsics::copy::<u8>(src, dst, 1);
+}
+
+unsafe fn use_copy_intrinsic_ref(src: *const u8, dst: *mut u8) {
+    let copy2 = &intrinsics::copy::<u8>;
+    copy2(src, dst, 1);
+}
+
+const ABC: u8 = 6 * 7;
+
+fn use_const() -> u8 {
+    ABC
+}
+
+pub fn call_closure_3arg() {
+    (|_, _, _| {})(0u8, 42u16, 0u8)
+}
+
+pub fn call_closure_2arg() {
+    (|_, _| {})(0u8, 42u16)
+}
+
+struct IsNotEmpty;
+
+impl<'a, 'b> FnOnce<(&'a &'b [u16],)> for IsNotEmpty {
+    type Output = (u8, u8);
+
+    #[inline]
+    extern "rust-call" fn call_once(mut self, arg: (&'a &'b [u16],)) -> (u8, u8) {
+        self.call_mut(arg)
+    }
+}
+
+impl<'a, 'b> FnMut<(&'a &'b [u16],)> for IsNotEmpty {
+    #[inline]
+    extern "rust-call" fn call_mut(&mut self, _arg: (&'a &'b [u16],)) -> (u8, u8) {
+        (0, 42)
+    }
+}
+
+pub fn call_is_not_empty() {
+    IsNotEmpty.call_once((&(&[0u16] as &[_]),));
+}
+
+fn eq_char(a: char, b: char) -> bool {
+    a == b
+}
+
+unsafe fn transmute(c: char) -> u32 {
+    intrinsics::transmute(c)
+}
+
+unsafe fn deref_str_ptr(s: *const str) -> &'static str {
+    &*s
+}
+
+fn use_array(arr: [u8; 3]) -> u8 {
+    arr[1]
+}
+
+fn repeat_array() -> [u8; 3] {
+    [0; 3]
+}
+
+fn array_as_slice(arr: &[u8; 3]) -> &[u8] {
+    arr
+}
+
+unsafe fn use_ctlz_nonzero(a: u16) -> u16 {
+    intrinsics::ctlz_nonzero(a)
+}
+
+fn ptr_as_usize(ptr: *const u8) -> usize {
+    ptr as usize
+}
+
+fn float_cast(a: f32, b: f64) -> (f64, f32) {
+    (a as f64, b as f32)
+}
+
+fn int_to_float(a: u8, b: i32) -> (f64, f32) {
+    (a as f64, b as f32)
+}
+
+fn make_array() -> [u8; 3] {
+    [42, 0, 5]
+}
+
+fn some_promoted_tuple() -> &'static (&'static str, &'static str) {
+    &("abc", "some")
+}
+
+fn index_slice(s: &[u8]) -> u8 {
+    s[2]
+}
+
+pub struct StrWrapper {
+    s: str,
+}
+
+fn str_wrapper_get(w: &StrWrapper) -> &str {
+    &w.s
+}
+
+fn i16_as_i8(a: i16) -> i8 {
+    a as i8
+}
+
+struct Unsized(u8, str);
+
+fn get_sized_field_ref_from_unsized_type(u: &Unsized) -> &u8 {
+    &u.0
+}
+
+fn get_unsized_field_ref_from_unsized_type(u: &Unsized) -> &str {
+    &u.1
+}
+
+pub fn reuse_byref_argument_storage(a: (u8, u16, u32)) -> u8 {
+    a.0
+}
diff --git a/compiler/rustc_codegen_gcc/example/mini_core.rs b/compiler/rustc_codegen_gcc/example/mini_core.rs
new file mode 100644
index 00000000000..1067cee8814
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/example/mini_core.rs
@@ -0,0 +1,585 @@
+#![feature(
+    no_core, lang_items, intrinsics, unboxed_closures, type_ascription, extern_types,
+    untagged_unions, decl_macro, rustc_attrs, transparent_unions, auto_traits,
+    thread_local
+)]
+#![no_core]
+#![allow(dead_code)]
+
+#[no_mangle]
+unsafe extern "C" fn _Unwind_Resume() {
+    intrinsics::unreachable();
+}
+
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "unsize"]
+pub trait Unsize<T: ?Sized> {}
+
+#[lang = "coerce_unsized"]
+pub trait CoerceUnsized<T> {}
+
+impl<'a, 'b: 'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<&'a U> for &'b T {}
+impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<&'a mut U> for &'a mut T {}
+impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for *const T {}
+impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*mut U> for *mut T {}
+
+#[lang = "dispatch_from_dyn"]
+pub trait DispatchFromDyn<T> {}
+
+// &T -> &U
+impl<'a, T: ?Sized+Unsize<U>, U: ?Sized> DispatchFromDyn<&'a U> for &'a T {}
+// &mut T -> &mut U
+impl<'a, T: ?Sized+Unsize<U>, U: ?Sized> DispatchFromDyn<&'a mut U> for &'a mut T {}
+// *const T -> *const U
+impl<T: ?Sized+Unsize<U>, U: ?Sized> DispatchFromDyn<*const U> for *const T {}
+// *mut T -> *mut U
+impl<T: ?Sized+Unsize<U>, U: ?Sized> DispatchFromDyn<*mut U> for *mut T {}
+impl<T: ?Sized + Unsize<U>, U: ?Sized> DispatchFromDyn<Box<U>> for Box<T> {}
+
+#[lang = "receiver"]
+pub trait Receiver {}
+
+impl<T: ?Sized> Receiver for &T {}
+impl<T: ?Sized> Receiver for &mut T {}
+impl<T: ?Sized> Receiver for Box<T> {}
+
+#[lang = "copy"]
+pub unsafe trait Copy {}
+
+unsafe impl Copy for bool {}
+unsafe impl Copy for u8 {}
+unsafe impl Copy for u16 {}
+unsafe impl Copy for u32 {}
+unsafe impl Copy for u64 {}
+unsafe impl Copy for usize {}
+unsafe impl Copy for i8 {}
+unsafe impl Copy for i16 {}
+unsafe impl Copy for i32 {}
+unsafe impl Copy for isize {}
+unsafe impl Copy for f32 {}
+unsafe impl Copy for char {}
+unsafe impl<'a, T: ?Sized> Copy for &'a T {}
+unsafe impl<T: ?Sized> Copy for *const T {}
+unsafe impl<T: ?Sized> Copy for *mut T {}
+
+#[lang = "sync"]
+pub unsafe trait Sync {}
+
+unsafe impl Sync for bool {}
+unsafe impl Sync for u8 {}
+unsafe impl Sync for u16 {}
+unsafe impl Sync for u32 {}
+unsafe impl Sync for u64 {}
+unsafe impl Sync for usize {}
+unsafe impl Sync for i8 {}
+unsafe impl Sync for i16 {}
+unsafe impl Sync for i32 {}
+unsafe impl Sync for isize {}
+unsafe impl Sync for char {}
+unsafe impl<'a, T: ?Sized> Sync for &'a T {}
+unsafe impl Sync for [u8; 16] {}
+
+#[lang = "freeze"]
+unsafe auto trait Freeze {}
+
+unsafe impl<T: ?Sized> Freeze for PhantomData<T> {}
+unsafe impl<T: ?Sized> Freeze for *const T {}
+unsafe impl<T: ?Sized> Freeze for *mut T {}
+unsafe impl<T: ?Sized> Freeze for &T {}
+unsafe impl<T: ?Sized> Freeze for &mut T {}
+
+#[lang = "structural_peq"]
+pub trait StructuralPartialEq {}
+
+#[lang = "structural_teq"]
+pub trait StructuralEq {}
+
+#[lang = "not"]
+pub trait Not {
+    type Output;
+
+    fn not(self) -> Self::Output;
+}
+
+impl Not for bool {
+    type Output = bool;
+
+    fn not(self) -> bool {
+        !self
+    }
+}
+
+#[lang = "mul"]
+pub trait Mul<RHS = Self> {
+    type Output;
+
+    #[must_use]
+    fn mul(self, rhs: RHS) -> Self::Output;
+}
+
+impl Mul for u8 {
+    type Output = Self;
+
+    fn mul(self, rhs: Self) -> Self::Output {
+        self * rhs
+    }
+}
+
+impl Mul for usize {
+    type Output = Self;
+
+    fn mul(self, rhs: Self) -> Self::Output {
+        self * rhs
+    }
+}
+
+#[lang = "add"]
+pub trait Add<RHS = Self> {
+    type Output;
+
+    fn add(self, rhs: RHS) -> Self::Output;
+}
+
+impl Add for u8 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for i8 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for usize {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+#[lang = "sub"]
+pub trait Sub<RHS = Self> {
+    type Output;
+
+    fn sub(self, rhs: RHS) -> Self::Output;
+}
+
+impl Sub for usize {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for u8 {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for i8 {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for i16 {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+#[lang = "rem"]
+pub trait Rem<RHS = Self> {
+    type Output;
+
+    fn rem(self, rhs: RHS) -> Self::Output;
+}
+
+impl Rem for usize {
+    type Output = Self;
+
+    fn rem(self, rhs: Self) -> Self {
+        self % rhs
+    }
+}
+
+#[lang = "bitor"]
+pub trait BitOr<RHS = Self> {
+    type Output;
+
+    #[must_use]
+    fn bitor(self, rhs: RHS) -> Self::Output;
+}
+
+impl BitOr for bool {
+    type Output = bool;
+
+    fn bitor(self, rhs: bool) -> bool {
+        self | rhs
+    }
+}
+
+impl<'a> BitOr<bool> for &'a bool {
+    type Output = bool;
+
+    fn bitor(self, rhs: bool) -> bool {
+        *self | rhs
+    }
+}
+
+#[lang = "eq"]
+pub trait PartialEq<Rhs: ?Sized = Self> {
+    fn eq(&self, other: &Rhs) -> bool;
+    fn ne(&self, other: &Rhs) -> bool;
+}
+
+impl PartialEq for u8 {
+    fn eq(&self, other: &u8) -> bool {
+        (*self) == (*other)
+    }
+    fn ne(&self, other: &u8) -> bool {
+        (*self) != (*other)
+    }
+}
+
+impl PartialEq for u16 {
+    fn eq(&self, other: &u16) -> bool {
+        (*self) == (*other)
+    }
+    fn ne(&self, other: &u16) -> bool {
+        (*self) != (*other)
+    }
+}
+
+impl PartialEq for u32 {
+    fn eq(&self, other: &u32) -> bool {
+        (*self) == (*other)
+    }
+    fn ne(&self, other: &u32) -> bool {
+        (*self) != (*other)
+    }
+}
+
+
+impl PartialEq for u64 {
+    fn eq(&self, other: &u64) -> bool {
+        (*self) == (*other)
+    }
+    fn ne(&self, other: &u64) -> bool {
+        (*self) != (*other)
+    }
+}
+
+impl PartialEq for usize {
+    fn eq(&self, other: &usize) -> bool {
+        (*self) == (*other)
+    }
+    fn ne(&self, other: &usize) -> bool {
+        (*self) != (*other)
+    }
+}
+
+impl PartialEq for i8 {
+    fn eq(&self, other: &i8) -> bool {
+        (*self) == (*other)
+    }
+    fn ne(&self, other: &i8) -> bool {
+        (*self) != (*other)
+    }
+}
+
+impl PartialEq for i32 {
+    fn eq(&self, other: &i32) -> bool {
+        (*self) == (*other)
+    }
+    fn ne(&self, other: &i32) -> bool {
+        (*self) != (*other)
+    }
+}
+
+impl PartialEq for isize {
+    fn eq(&self, other: &isize) -> bool {
+        (*self) == (*other)
+    }
+    fn ne(&self, other: &isize) -> bool {
+        (*self) != (*other)
+    }
+}
+
+impl PartialEq for char {
+    fn eq(&self, other: &char) -> bool {
+        (*self) == (*other)
+    }
+    fn ne(&self, other: &char) -> bool {
+        (*self) != (*other)
+    }
+}
+
+impl<T: ?Sized> PartialEq for *const T {
+    fn eq(&self, other: &*const T) -> bool {
+        *self == *other
+    }
+    fn ne(&self, other: &*const T) -> bool {
+        *self != *other
+    }
+}
+
+#[lang = "neg"]
+pub trait Neg {
+    type Output;
+
+    fn neg(self) -> Self::Output;
+}
+
+impl Neg for i8 {
+    type Output = i8;
+
+    fn neg(self) -> i8 {
+        -self
+    }
+}
+
+impl Neg for i16 {
+    type Output = i16;
+
+    fn neg(self) -> i16 {
+        self
+    }
+}
+
+impl Neg for isize {
+    type Output = isize;
+
+    fn neg(self) -> isize {
+        -self
+    }
+}
+
+impl Neg for f32 {
+    type Output = f32;
+
+    fn neg(self) -> f32 {
+        -self
+    }
+}
+
+pub enum Option<T> {
+    Some(T),
+    None,
+}
+
+pub use Option::*;
+
+#[lang = "phantom_data"]
+pub struct PhantomData<T: ?Sized>;
+
+#[lang = "fn_once"]
+#[rustc_paren_sugar]
+pub trait FnOnce<Args> {
+    #[lang = "fn_once_output"]
+    type Output;
+
+    extern "rust-call" fn call_once(self, args: Args) -> Self::Output;
+}
+
+#[lang = "fn_mut"]
+#[rustc_paren_sugar]
+pub trait FnMut<Args>: FnOnce<Args> {
+    extern "rust-call" fn call_mut(&mut self, args: Args) -> Self::Output;
+}
+
+#[lang = "panic"]
+#[track_caller]
+pub fn panic(_msg: &str) -> ! {
+    unsafe {
+        libc::puts("Panicking\n\0" as *const str as *const u8);
+        intrinsics::abort();
+    }
+}
+
+#[lang = "panic_bounds_check"]
+#[track_caller]
+fn panic_bounds_check(index: usize, len: usize) -> ! {
+    unsafe {
+        libc::printf("index out of bounds: the len is %d but the index is %d\n\0" as *const str as *const i8, len, index);
+        intrinsics::abort();
+    }
+}
+
+#[lang = "eh_personality"]
+fn eh_personality() -> ! {
+    loop {}
+}
+
+#[lang = "drop_in_place"]
+#[allow(unconditional_recursion)]
+pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
+    // Code here does not matter - this is replaced by the
+    // real drop glue by the compiler.
+    drop_in_place(to_drop);
+}
+
+#[lang = "deref"]
+pub trait Deref {
+    type Target: ?Sized;
+
+    fn deref(&self) -> &Self::Target;
+}
+
+#[lang = "owned_box"]
+pub struct Box<T: ?Sized>(*mut T);
+
+impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<Box<U>> for Box<T> {}
+
+impl<T: ?Sized> Drop for Box<T> {
+    fn drop(&mut self) {
+        // drop is currently performed by compiler.
+    }
+}
+
+impl<T> Deref for Box<T> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
+        &**self
+    }
+}
+
+#[lang = "exchange_malloc"]
+unsafe fn allocate(size: usize, _align: usize) -> *mut u8 {
+    libc::malloc(size)
+}
+
+#[lang = "box_free"]
+unsafe fn box_free<T: ?Sized>(ptr: *mut T) {
+    libc::free(ptr as *mut u8);
+}
+
+#[lang = "drop"]
+pub trait Drop {
+    fn drop(&mut self);
+}
+
+#[lang = "manually_drop"]
+#[repr(transparent)]
+pub struct ManuallyDrop<T: ?Sized> {
+    pub value: T,
+}
+
+#[lang = "maybe_uninit"]
+#[repr(transparent)]
+pub union MaybeUninit<T> {
+    pub uninit: (),
+    pub value: ManuallyDrop<T>,
+}
+
+pub mod intrinsics {
+    extern "rust-intrinsic" {
+        pub fn abort() -> !;
+        pub fn size_of<T>() -> usize;
+        pub fn size_of_val<T: ?::Sized>(val: *const T) -> usize;
+        pub fn min_align_of<T>() -> usize;
+        pub fn min_align_of_val<T: ?::Sized>(val: *const T) -> usize;
+        pub fn copy<T>(src: *const T, dst: *mut T, count: usize);
+        pub fn transmute<T, U>(e: T) -> U;
+        pub fn ctlz_nonzero<T>(x: T) -> T;
+        pub fn needs_drop<T>() -> bool;
+        pub fn bitreverse<T>(x: T) -> T;
+        pub fn bswap<T>(x: T) -> T;
+        pub fn write_bytes<T>(dst: *mut T, val: u8, count: usize);
+        pub fn unreachable() -> !;
+    }
+}
+
+pub mod libc {
+    #[link(name = "c")]
+    extern "C" {
+        pub fn puts(s: *const u8) -> i32;
+        pub fn printf(format: *const i8, ...) -> i32;
+        pub fn malloc(size: usize) -> *mut u8;
+        pub fn free(ptr: *mut u8);
+        pub fn memcpy(dst: *mut u8, src: *const u8, size: usize);
+        pub fn memmove(dst: *mut u8, src: *const u8, size: usize);
+        pub fn strncpy(dst: *mut u8, src: *const u8, size: usize);
+    }
+}
+
+#[lang = "index"]
+pub trait Index<Idx: ?Sized> {
+    type Output: ?Sized;
+    fn index(&self, index: Idx) -> &Self::Output;
+}
+
+impl<T> Index<usize> for [T; 3] {
+    type Output = T;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        &self[index]
+    }
+}
+
+impl<T> Index<usize> for [T] {
+    type Output = T;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        &self[index]
+    }
+}
+
+extern {
+    type VaListImpl;
+}
+
+#[lang = "va_list"]
+#[repr(transparent)]
+pub struct VaList<'a>(&'a mut VaListImpl);
+
+#[rustc_builtin_macro]
+#[rustc_macro_transparency = "semitransparent"]
+pub macro stringify($($t:tt)*) { /* compiler built-in */ }
+
+#[rustc_builtin_macro]
+#[rustc_macro_transparency = "semitransparent"]
+pub macro file() { /* compiler built-in */ }
+
+#[rustc_builtin_macro]
+#[rustc_macro_transparency = "semitransparent"]
+pub macro line() { /* compiler built-in */ }
+
+#[rustc_builtin_macro]
+#[rustc_macro_transparency = "semitransparent"]
+pub macro cfg() { /* compiler built-in */ }
+
+pub static A_STATIC: u8 = 42;
+
+#[lang = "panic_location"]
+struct PanicLocation {
+    file: &'static str,
+    line: u32,
+    column: u32,
+}
+
+#[no_mangle]
+pub fn get_tls() -> u8 {
+    #[thread_local]
+    static A: u8 = 42;
+
+    A
+}
diff --git a/compiler/rustc_codegen_gcc/example/mini_core_hello_world.rs b/compiler/rustc_codegen_gcc/example/mini_core_hello_world.rs
new file mode 100644
index 00000000000..69d591565ac
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/example/mini_core_hello_world.rs
@@ -0,0 +1,424 @@
+// Adapted from https://github.com/sunfishcode/mir2cranelift/blob/master/rust-examples/nocore-hello-world.rs
+
+#![feature(
+    no_core, unboxed_closures, start, lang_items, box_syntax, never_type, linkage,
+    extern_types, thread_local
+)]
+#![no_core]
+#![allow(dead_code, non_camel_case_types)]
+
+extern crate mini_core;
+
+use mini_core::*;
+use mini_core::libc::*;
+
+unsafe extern "C" fn my_puts(s: *const u8) {
+    puts(s);
+}
+
+#[lang = "termination"]
+trait Termination {
+    fn report(self) -> i32;
+}
+
+impl Termination for () {
+    fn report(self) -> i32 {
+        unsafe {
+            NUM = 6 * 7 + 1 + (1u8 == 1u8) as u8; // 44
+            *NUM_REF as i32
+        }
+    }
+}
+
+trait SomeTrait {
+    fn object_safe(&self);
+}
+
+impl SomeTrait for &'static str {
+    fn object_safe(&self) {
+        unsafe {
+            puts(*self as *const str as *const u8);
+        }
+    }
+}
+
+struct NoisyDrop {
+    text: &'static str,
+    inner: NoisyDropInner,
+}
+
+struct NoisyDropInner;
+
+impl Drop for NoisyDrop {
+    fn drop(&mut self) {
+        unsafe {
+            puts(self.text as *const str as *const u8);
+        }
+    }
+}
+
+impl Drop for NoisyDropInner {
+    fn drop(&mut self) {
+        unsafe {
+            puts("Inner got dropped!\0" as *const str as *const u8);
+        }
+    }
+}
+
+impl SomeTrait for NoisyDrop {
+    fn object_safe(&self) {}
+}
+
+enum Ordering {
+    Less = -1,
+    Equal = 0,
+    Greater = 1,
+}
+
+#[lang = "start"]
+fn start<T: Termination + 'static>(
+    main: fn() -> T,
+    argc: isize,
+    argv: *const *const u8,
+) -> isize {
+    if argc == 3 {
+        unsafe { puts(*argv); }
+        unsafe { puts(*((argv as usize + intrinsics::size_of::<*const u8>()) as *const *const u8)); }
+        unsafe { puts(*((argv as usize + 2 * intrinsics::size_of::<*const u8>()) as *const *const u8)); }
+    }
+
+    main().report();
+    0
+}
+
+static mut NUM: u8 = 6 * 7;
+static NUM_REF: &'static u8 = unsafe { &NUM };
+
+macro_rules! assert {
+    ($e:expr) => {
+        if !$e {
+            panic(stringify!(! $e));
+        }
+    };
+}
+
+macro_rules! assert_eq {
+    ($l:expr, $r: expr) => {
+        if $l != $r {
+            panic(stringify!($l != $r));
+        }
+    }
+}
+
+struct Unique<T: ?Sized> {
+    pointer: *const T,
+    _marker: PhantomData<T>,
+}
+
+impl<T: ?Sized, U: ?Sized> CoerceUnsized<Unique<U>> for Unique<T> where T: Unsize<U> {}
+
+unsafe fn zeroed<T>() -> T {
+    let mut uninit = MaybeUninit { uninit: () };
+    intrinsics::write_bytes(&mut uninit.value.value as *mut T, 0, 1);
+    uninit.value.value
+}
+
+fn take_f32(_f: f32) {}
+fn take_unique(_u: Unique<()>) {}
+
+fn return_u128_pair() -> (u128, u128) {
+    (0, 0)
+}
+
+fn call_return_u128_pair() {
+    return_u128_pair();
+}
+
+fn main() {
+    take_unique(Unique {
+        pointer: 0 as *const (),
+        _marker: PhantomData,
+    });
+    take_f32(0.1);
+
+    //call_return_u128_pair();
+
+    let slice = &[0, 1] as &[i32];
+    let slice_ptr = slice as *const [i32] as *const i32;
+
+    assert_eq!(slice_ptr as usize % 4, 0);
+
+    //return;
+
+    unsafe {
+        printf("Hello %s\n\0" as *const str as *const i8, "printf\0" as *const str as *const i8);
+
+        let hello: &[u8] = b"Hello\0" as &[u8; 6];
+        let ptr: *const u8 = hello as *const [u8] as *const u8;
+        puts(ptr);
+
+        let world: Box<&str> = box "World!\0";
+        puts(*world as *const str as *const u8);
+        world as Box<dyn SomeTrait>;
+
+        assert_eq!(intrinsics::bitreverse(0b10101000u8), 0b00010101u8);
+
+        assert_eq!(intrinsics::bswap(0xabu8), 0xabu8);
+        assert_eq!(intrinsics::bswap(0xddccu16), 0xccddu16);
+        assert_eq!(intrinsics::bswap(0xffee_ddccu32), 0xccdd_eeffu32);
+        assert_eq!(intrinsics::bswap(0x1234_5678_ffee_ddccu64), 0xccdd_eeff_7856_3412u64);
+
+        assert_eq!(intrinsics::size_of_val(hello) as u8, 6);
+
+        let chars = &['C', 'h', 'a', 'r', 's'];
+        let chars = chars as &[char];
+        assert_eq!(intrinsics::size_of_val(chars) as u8, 4 * 5);
+
+        let a: &dyn SomeTrait = &"abc\0";
+        a.object_safe();
+
+        assert_eq!(intrinsics::size_of_val(a) as u8, 16);
+        assert_eq!(intrinsics::size_of_val(&0u32) as u8, 4);
+
+        assert_eq!(intrinsics::min_align_of::<u16>() as u8, 2);
+        assert_eq!(intrinsics::min_align_of_val(&a) as u8, intrinsics::min_align_of::<&str>() as u8);
+
+        assert!(!intrinsics::needs_drop::<u8>());
+        assert!(intrinsics::needs_drop::<NoisyDrop>());
+
+        Unique {
+            pointer: 0 as *const &str,
+            _marker: PhantomData,
+        } as Unique<dyn SomeTrait>;
+
+        struct MyDst<T: ?Sized>(T);
+
+        intrinsics::size_of_val(&MyDst([0u8; 4]) as &MyDst<[u8]>);
+
+        struct Foo {
+            x: u8,
+            y: !,
+        }
+
+        unsafe fn uninitialized<T>() -> T {
+            MaybeUninit { uninit: () }.value.value
+        }
+
+        zeroed::<(u8, u8)>();
+        #[allow(unreachable_code)]
+        {
+            if false {
+                zeroed::<!>();
+                zeroed::<Foo>();
+                uninitialized::<Foo>();
+            }
+        }
+    }
+
+    let _ = box NoisyDrop {
+        text: "Boxed outer got dropped!\0",
+        inner: NoisyDropInner,
+    } as Box<dyn SomeTrait>;
+
+    const FUNC_REF: Option<fn()> = Some(main);
+    match FUNC_REF {
+        Some(_) => {},
+        None => assert!(false),
+    }
+
+    match Ordering::Less {
+        Ordering::Less => {},
+        _ => assert!(false),
+    }
+
+    [NoisyDropInner, NoisyDropInner];
+
+    let x = &[0u32, 42u32] as &[u32];
+    match x {
+        [] => assert_eq!(0u32, 1),
+        [_, ref y @ ..] => assert_eq!(&x[1] as *const u32 as usize, &y[0] as *const u32 as usize),
+    }
+
+    assert_eq!(((|()| 42u8) as fn(()) -> u8)(()), 42);
+
+    extern {
+        #[linkage = "weak"]
+        static ABC: *const u8;
+    }
+
+    {
+        extern {
+            #[linkage = "weak"]
+            static ABC: *const u8;
+        }
+    }
+
+    // TODO(antoyo): to make this work, support weak linkage.
+    //unsafe { assert_eq!(ABC as usize, 0); }
+
+    &mut (|| Some(0 as *const ())) as &mut dyn FnMut() -> Option<*const ()>;
+
+    let f = 1000.0;
+    assert_eq!(f as u8, 255);
+    let f2 = -1000.0;
+    assert_eq!(f2 as i8, -128);
+    assert_eq!(f2 as u8, 0);
+
+    static ANOTHER_STATIC: &u8 = &A_STATIC;
+    assert_eq!(*ANOTHER_STATIC, 42);
+
+    check_niche_behavior();
+
+    extern "C" {
+        type ExternType;
+    }
+
+    struct ExternTypeWrapper {
+        _a: ExternType,
+    }
+
+    let nullptr = 0 as *const ();
+    let extern_nullptr = nullptr as *const ExternTypeWrapper;
+    extern_nullptr as *const ();
+    let slice_ptr = &[] as *const [u8];
+    slice_ptr as *const u8;
+
+    #[cfg(not(jit))]
+    test_tls();
+}
+
+#[repr(C)]
+enum c_void {
+    _1,
+    _2,
+}
+
+type c_int = i32;
+type c_ulong = u64;
+
+type pthread_t = c_ulong;
+
+#[repr(C)]
+struct pthread_attr_t {
+    __size: [u64; 7],
+}
+
+#[link(name = "pthread")]
+extern "C" {
+    fn pthread_attr_init(attr: *mut pthread_attr_t) -> c_int;
+
+    fn pthread_create(
+        native: *mut pthread_t,
+        attr: *const pthread_attr_t,
+        f: extern "C" fn(_: *mut c_void) -> *mut c_void,
+        value: *mut c_void
+    ) -> c_int;
+
+    fn pthread_join(
+        native: pthread_t,
+        value: *mut *mut c_void
+    ) -> c_int;
+}
+
+#[thread_local]
+#[cfg(not(jit))]
+static mut TLS: u8 = 42;
+
+#[cfg(not(jit))]
+extern "C" fn mutate_tls(_: *mut c_void) -> *mut c_void {
+    unsafe { TLS = 0; }
+    0 as *mut c_void
+}
+
+#[cfg(not(jit))]
+fn test_tls() {
+    unsafe {
+        let mut attr: pthread_attr_t = zeroed();
+        let mut thread: pthread_t = 0;
+
+        assert_eq!(TLS, 42);
+
+        if pthread_attr_init(&mut attr) != 0 {
+            assert!(false);
+        }
+
+        if pthread_create(&mut thread, &attr, mutate_tls, 0 as *mut c_void) != 0 {
+            assert!(false);
+        }
+
+        let mut res = 0 as *mut c_void;
+        pthread_join(thread, &mut res);
+
+        // TLS of main thread must not have been changed by the other thread.
+        assert_eq!(TLS, 42);
+
+        puts("TLS works!\n\0" as *const str as *const u8);
+    }
+}
+
+// Copied ui/issues/issue-61696.rs
+
+pub enum Infallible {}
+
+// The check that the `bool` field of `V1` is encoding a "niche variant"
+// (i.e. not `V1`, so `V3` or `V4`) used to be mathematically incorrect,
+// causing valid `V1` values to be interpreted as other variants.
+pub enum E1 {
+    V1 { f: bool },
+    V2 { f: Infallible },
+    V3,
+    V4,
+}
+
+// Computing the discriminant used to be done using the niche type (here `u8`,
+// from the `bool` field of `V1`), overflowing for variants with large enough
+// indices (`V3` and `V4`), causing them to be interpreted as other variants.
+pub enum E2<X> {
+    V1 { f: bool },
+
+    /*_00*/ _01(X), _02(X), _03(X), _04(X), _05(X), _06(X), _07(X),
+    _08(X), _09(X), _0A(X), _0B(X), _0C(X), _0D(X), _0E(X), _0F(X),
+    _10(X), _11(X), _12(X), _13(X), _14(X), _15(X), _16(X), _17(X),
+    _18(X), _19(X), _1A(X), _1B(X), _1C(X), _1D(X), _1E(X), _1F(X),
+    _20(X), _21(X), _22(X), _23(X), _24(X), _25(X), _26(X), _27(X),
+    _28(X), _29(X), _2A(X), _2B(X), _2C(X), _2D(X), _2E(X), _2F(X),
+    _30(X), _31(X), _32(X), _33(X), _34(X), _35(X), _36(X), _37(X),
+    _38(X), _39(X), _3A(X), _3B(X), _3C(X), _3D(X), _3E(X), _3F(X),
+    _40(X), _41(X), _42(X), _43(X), _44(X), _45(X), _46(X), _47(X),
+    _48(X), _49(X), _4A(X), _4B(X), _4C(X), _4D(X), _4E(X), _4F(X),
+    _50(X), _51(X), _52(X), _53(X), _54(X), _55(X), _56(X), _57(X),
+    _58(X), _59(X), _5A(X), _5B(X), _5C(X), _5D(X), _5E(X), _5F(X),
+    _60(X), _61(X), _62(X), _63(X), _64(X), _65(X), _66(X), _67(X),
+    _68(X), _69(X), _6A(X), _6B(X), _6C(X), _6D(X), _6E(X), _6F(X),
+    _70(X), _71(X), _72(X), _73(X), _74(X), _75(X), _76(X), _77(X),
+    _78(X), _79(X), _7A(X), _7B(X), _7C(X), _7D(X), _7E(X), _7F(X),
+    _80(X), _81(X), _82(X), _83(X), _84(X), _85(X), _86(X), _87(X),
+    _88(X), _89(X), _8A(X), _8B(X), _8C(X), _8D(X), _8E(X), _8F(X),
+    _90(X), _91(X), _92(X), _93(X), _94(X), _95(X), _96(X), _97(X),
+    _98(X), _99(X), _9A(X), _9B(X), _9C(X), _9D(X), _9E(X), _9F(X),
+    _A0(X), _A1(X), _A2(X), _A3(X), _A4(X), _A5(X), _A6(X), _A7(X),
+    _A8(X), _A9(X), _AA(X), _AB(X), _AC(X), _AD(X), _AE(X), _AF(X),
+    _B0(X), _B1(X), _B2(X), _B3(X), _B4(X), _B5(X), _B6(X), _B7(X),
+    _B8(X), _B9(X), _BA(X), _BB(X), _BC(X), _BD(X), _BE(X), _BF(X),
+    _C0(X), _C1(X), _C2(X), _C3(X), _C4(X), _C5(X), _C6(X), _C7(X),
+    _C8(X), _C9(X), _CA(X), _CB(X), _CC(X), _CD(X), _CE(X), _CF(X),
+    _D0(X), _D1(X), _D2(X), _D3(X), _D4(X), _D5(X), _D6(X), _D7(X),
+    _D8(X), _D9(X), _DA(X), _DB(X), _DC(X), _DD(X), _DE(X), _DF(X),
+    _E0(X), _E1(X), _E2(X), _E3(X), _E4(X), _E5(X), _E6(X), _E7(X),
+    _E8(X), _E9(X), _EA(X), _EB(X), _EC(X), _ED(X), _EE(X), _EF(X),
+    _F0(X), _F1(X), _F2(X), _F3(X), _F4(X), _F5(X), _F6(X), _F7(X),
+    _F8(X), _F9(X), _FA(X), _FB(X), _FC(X), _FD(X), _FE(X), _FF(X),
+
+    V3,
+    V4,
+}
+
+fn check_niche_behavior () {
+    if let E1::V2 { .. } = (E1::V1 { f: true }) {
+        intrinsics::abort();
+    }
+
+    if let E2::V1 { .. } = E2::V3::<Infallible> {
+        intrinsics::abort();
+    }
+}
diff --git a/compiler/rustc_codegen_gcc/example/mod_bench.rs b/compiler/rustc_codegen_gcc/example/mod_bench.rs
new file mode 100644
index 00000000000..2e2b0052dee
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/example/mod_bench.rs
@@ -0,0 +1,37 @@
+#![feature(start, box_syntax, core_intrinsics, lang_items)]
+#![no_std]
+
+#[link(name = "c")]
+extern {}
+
+#[panic_handler]
+fn panic_handler(_: &core::panic::PanicInfo) -> ! {
+    unsafe {
+        core::intrinsics::abort();
+    }
+}
+
+#[lang="eh_personality"]
+fn eh_personality(){}
+
+// Required for rustc_codegen_llvm
+#[no_mangle]
+unsafe extern "C" fn _Unwind_Resume() {
+    core::intrinsics::unreachable();
+}
+
+#[start]
+fn main(_argc: isize, _argv: *const *const u8) -> isize {
+    for i in 2..100_000_000 {
+        black_box((i + 1) % i);
+    }
+
+    0
+}
+
+#[inline(never)]
+fn black_box(i: u32) {
+    if i != 1 {
+        unsafe { core::intrinsics::abort(); }
+    }
+}
diff --git a/compiler/rustc_codegen_gcc/example/std_example.rs b/compiler/rustc_codegen_gcc/example/std_example.rs
new file mode 100644
index 00000000000..eba0eb82896
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/example/std_example.rs
@@ -0,0 +1,278 @@
+#![feature(core_intrinsics, generators, generator_trait, is_sorted)]
+
+use std::arch::x86_64::*;
+use std::io::Write;
+use std::ops::Generator;
+
+extern {
+    pub fn printf(format: *const i8, ...) -> i32;
+}
+
+fn main() {
+    let mutex = std::sync::Mutex::new(());
+    let _guard = mutex.lock().unwrap();
+
+    let _ = ::std::iter::repeat('a' as u8).take(10).collect::<Vec<_>>();
+    let stderr = ::std::io::stderr();
+    let mut stderr = stderr.lock();
+
+    std::thread::spawn(move || {
+        println!("Hello from another thread!");
+    });
+
+    writeln!(stderr, "some {} text", "<unknown>").unwrap();
+
+    let _ = std::process::Command::new("true").env("c", "d").spawn();
+
+    println!("cargo:rustc-link-lib=z");
+
+    static ONCE: std::sync::Once = std::sync::Once::new();
+    ONCE.call_once(|| {});
+
+    let _eq = LoopState::Continue(()) == LoopState::Break(());
+
+    // Make sure ByValPair values with differently sized components are correctly passed
+    map(None::<(u8, Box<Instruction>)>);
+
+    println!("{}", 2.3f32.exp());
+    println!("{}", 2.3f32.exp2());
+    println!("{}", 2.3f32.abs());
+    println!("{}", 2.3f32.sqrt());
+    println!("{}", 2.3f32.floor());
+    println!("{}", 2.3f32.ceil());
+    println!("{}", 2.3f32.min(1.0));
+    println!("{}", 2.3f32.max(1.0));
+    println!("{}", 2.3f32.powi(2));
+    println!("{}", 2.3f32.log2());
+    assert_eq!(2.3f32.copysign(-1.0), -2.3f32);
+    println!("{}", 2.3f32.powf(2.0));
+
+    assert_eq!(-128i8, (-128i8).saturating_sub(1));
+    assert_eq!(127i8, 127i8.saturating_sub(-128));
+    assert_eq!(-128i8, (-128i8).saturating_add(-128));
+    assert_eq!(127i8, 127i8.saturating_add(1));
+
+    assert_eq!(-32768i16, (-32768i16).saturating_add(-32768));
+    assert_eq!(32767i16, 32767i16.saturating_add(1));
+
+    assert_eq!(0b0000000000000000000000000010000010000000000000000000000000000000_0000000000100000000000000000000000001000000000000100000000000000u128.leading_zeros(), 26);
+    assert_eq!(0b0000000000000000000000000010000000000000000000000000000000000000_0000000000000000000000000000000000001000000000000000000010000000u128.trailing_zeros(), 7);
+
+    let _d = 0i128.checked_div(2i128);
+    let _d = 0u128.checked_div(2u128);
+    assert_eq!(1u128 + 2, 3);
+
+    assert_eq!(0b100010000000000000000000000000000u128 >> 10, 0b10001000000000000000000u128);
+    assert_eq!(0xFEDCBA987654321123456789ABCDEFu128 >> 64, 0xFEDCBA98765432u128);
+    assert_eq!(0xFEDCBA987654321123456789ABCDEFu128 as i128 >> 64, 0xFEDCBA98765432i128);
+
+    let tmp = 353985398u128;
+    assert_eq!(tmp * 932490u128, 330087843781020u128);
+
+    let tmp = -0x1234_5678_9ABC_DEF0i64;
+    assert_eq!(tmp as i128, -0x1234_5678_9ABC_DEF0i128);
+
+    // Check that all u/i128 <-> float casts work correctly.
+    let houndred_u128 = 100u128;
+    let houndred_i128 = 100i128;
+    let houndred_f32 = 100.0f32;
+    let houndred_f64 = 100.0f64;
+    assert_eq!(houndred_u128 as f32, 100.0);
+    assert_eq!(houndred_u128 as f64, 100.0);
+    assert_eq!(houndred_f32 as u128, 100);
+    assert_eq!(houndred_f64 as u128, 100);
+    assert_eq!(houndred_i128 as f32, 100.0);
+    assert_eq!(houndred_i128 as f64, 100.0);
+    assert_eq!(houndred_f32 as i128, 100);
+    assert_eq!(houndred_f64 as i128, 100);
+
+    let _a = 1u32 << 2u8;
+
+    let empty: [i32; 0] = [];
+    assert!(empty.is_sorted());
+
+    println!("{:?}", std::intrinsics::caller_location());
+
+    /*unsafe {
+        test_simd();
+    }*/
+
+    Box::pin(move |mut _task_context| {
+        yield ();
+    }).as_mut().resume(0);
+
+    println!("End");
+}
+
+/*#[target_feature(enable = "sse2")]
+unsafe fn test_simd() {
+    let x = _mm_setzero_si128();
+    let y = _mm_set1_epi16(7);
+    let or = _mm_or_si128(x, y);
+    let cmp_eq = _mm_cmpeq_epi8(y, y);
+    let cmp_lt = _mm_cmplt_epi8(y, y);
+
+    /*assert_eq!(std::mem::transmute::<_, [u16; 8]>(or), [7, 7, 7, 7, 7, 7, 7, 7]);
+    assert_eq!(std::mem::transmute::<_, [u16; 8]>(cmp_eq), [0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff, 0xffff]);
+    assert_eq!(std::mem::transmute::<_, [u16; 8]>(cmp_lt), [0, 0, 0, 0, 0, 0, 0, 0]);
+
+    test_mm_slli_si128();
+    test_mm_movemask_epi8();
+    test_mm256_movemask_epi8();
+    test_mm_add_epi8();
+    test_mm_add_pd();
+    test_mm_cvtepi8_epi16();
+    test_mm_cvtsi128_si64();
+
+    // FIXME(#666) implement `#[rustc_arg_required_const(..)]` support
+    //test_mm_extract_epi8();
+
+    let mask1 = _mm_movemask_epi8(dbg!(_mm_setr_epi8(255u8 as i8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)));
+    assert_eq!(mask1, 1);*/
+}*/
+
+/*#[target_feature(enable = "sse2")]
+unsafe fn test_mm_slli_si128() {
+    #[rustfmt::skip]
+    let a = _mm_setr_epi8(
+        1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
+    );
+    let r = _mm_slli_si128(a, 1);
+    let e = _mm_setr_epi8(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15);
+    assert_eq_m128i(r, e);
+
+    #[rustfmt::skip]
+    let a = _mm_setr_epi8(
+        1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
+    );
+    let r = _mm_slli_si128(a, 15);
+    let e = _mm_setr_epi8(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1);
+    assert_eq_m128i(r, e);
+
+    #[rustfmt::skip]
+    let a = _mm_setr_epi8(
+        1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
+    );
+    let r = _mm_slli_si128(a, 16);
+    assert_eq_m128i(r, _mm_set1_epi8(0));
+
+    #[rustfmt::skip]
+    let a = _mm_setr_epi8(
+        1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
+    );
+    let r = _mm_slli_si128(a, -1);
+    assert_eq_m128i(_mm_set1_epi8(0), r);
+
+    #[rustfmt::skip]
+    let a = _mm_setr_epi8(
+        1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
+    );
+    let r = _mm_slli_si128(a, -0x80000000);
+    assert_eq_m128i(r, _mm_set1_epi8(0));
+}
+
+#[target_feature(enable = "sse2")]
+unsafe fn test_mm_movemask_epi8() {
+    #[rustfmt::skip]
+    let a = _mm_setr_epi8(
+        0b1000_0000u8 as i8, 0b0, 0b1000_0000u8 as i8, 0b01,
+        0b0101, 0b1111_0000u8 as i8, 0, 0,
+        0, 0, 0b1111_0000u8 as i8, 0b0101,
+        0b01, 0b1000_0000u8 as i8, 0b0, 0b1000_0000u8 as i8,
+    );
+    let r = _mm_movemask_epi8(a);
+    assert_eq!(r, 0b10100100_00100101);
+}
+
+#[target_feature(enable = "avx2")]
+unsafe fn test_mm256_movemask_epi8() {
+    let a = _mm256_set1_epi8(-1);
+    let r = _mm256_movemask_epi8(a);
+    let e = -1;
+    assert_eq!(r, e);
+}
+
+#[target_feature(enable = "sse2")]
+unsafe fn test_mm_add_epi8() {
+    let a = _mm_setr_epi8(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15);
+    #[rustfmt::skip]
+    let b = _mm_setr_epi8(
+        16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
+    );
+    let r = _mm_add_epi8(a, b);
+    #[rustfmt::skip]
+    let e = _mm_setr_epi8(
+        16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46,
+    );
+    assert_eq_m128i(r, e);
+}
+
+#[target_feature(enable = "sse2")]
+unsafe fn test_mm_add_pd() {
+    let a = _mm_setr_pd(1.0, 2.0);
+    let b = _mm_setr_pd(5.0, 10.0);
+    let r = _mm_add_pd(a, b);
+    assert_eq_m128d(r, _mm_setr_pd(6.0, 12.0));
+}
+
+fn assert_eq_m128i(x: std::arch::x86_64::__m128i, y: std::arch::x86_64::__m128i) {
+    unsafe {
+        assert_eq!(std::mem::transmute::<_, [u8; 16]>(x), std::mem::transmute::<_, [u8; 16]>(y));
+    }
+}
+
+#[target_feature(enable = "sse2")]
+pub unsafe fn assert_eq_m128d(a: __m128d, b: __m128d) {
+    if _mm_movemask_pd(_mm_cmpeq_pd(a, b)) != 0b11 {
+        panic!("{:?} != {:?}", a, b);
+    }
+}
+
+#[target_feature(enable = "sse2")]
+unsafe fn test_mm_cvtsi128_si64() {
+    let r = _mm_cvtsi128_si64(std::mem::transmute::<[i64; 2], _>([5, 0]));
+    assert_eq!(r, 5);
+}
+
+#[target_feature(enable = "sse4.1")]
+unsafe fn test_mm_cvtepi8_epi16() {
+    let a = _mm_set1_epi8(10);
+    let r = _mm_cvtepi8_epi16(a);
+    let e = _mm_set1_epi16(10);
+    assert_eq_m128i(r, e);
+    let a = _mm_set1_epi8(-10);
+    let r = _mm_cvtepi8_epi16(a);
+    let e = _mm_set1_epi16(-10);
+    assert_eq_m128i(r, e);
+}
+
+#[target_feature(enable = "sse4.1")]
+unsafe fn test_mm_extract_epi8() {
+    #[rustfmt::skip]
+    let a = _mm_setr_epi8(
+        -1, 1, 2, 3, 4, 5, 6, 7,
+        8, 9, 10, 11, 12, 13, 14, 15
+    );
+    let r1 = _mm_extract_epi8(a, 0);
+    let r2 = _mm_extract_epi8(a, 19);
+    assert_eq!(r1, 0xFF);
+    assert_eq!(r2, 3);
+}*/
+
+#[derive(PartialEq)]
+enum LoopState {
+    Continue(()),
+    Break(())
+}
+
+pub enum Instruction {
+    Increment,
+    Loop,
+}
+
+fn map(a: Option<(u8, Box<Instruction>)>) -> Option<Box<Instruction>> {
+    match a {
+        None => None,
+        Some((_, instr)) => Some(instr),
+    }
+}
diff --git a/compiler/rustc_codegen_gcc/example/subslice-patterns-const-eval.rs b/compiler/rustc_codegen_gcc/example/subslice-patterns-const-eval.rs
new file mode 100644
index 00000000000..2cb84786f56
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/example/subslice-patterns-const-eval.rs
@@ -0,0 +1,97 @@
+// Based on https://github.com/rust-lang/rust/blob/c5840f9d252c2f5cc16698dbf385a29c5de3ca07/src/test/ui/array-slice-vec/subslice-patterns-const-eval-match.rs
+
+// Test that array subslice patterns are correctly handled in const evaluation.
+
+// run-pass
+
+#[derive(PartialEq, Debug, Clone)]
+struct N(u8);
+
+#[derive(PartialEq, Debug, Clone)]
+struct Z;
+
+macro_rules! n {
+    ($($e:expr),* $(,)?) => {
+        [$(N($e)),*]
+    }
+}
+
+// This macro has an unused variable so that it can be repeated base on the
+// number of times a repeated variable (`$e` in `z`) occurs.
+macro_rules! zed {
+    ($e:expr) => { Z }
+}
+
+macro_rules! z {
+    ($($e:expr),* $(,)?) => {
+        [$(zed!($e)),*]
+    }
+}
+
+// Compare constant evaluation and runtime evaluation of a given expression.
+macro_rules! compare_evaluation {
+    ($e:expr, $t:ty $(,)?) => {{
+        const CONST_EVAL: $t = $e;
+        const fn const_eval() -> $t { $e }
+        static CONST_EVAL2: $t = const_eval();
+        let runtime_eval = $e;
+        assert_eq!(CONST_EVAL, runtime_eval);
+        assert_eq!(CONST_EVAL2, runtime_eval);
+    }}
+}
+
+// Repeat `$test`, substituting the given macro variables with the given
+// identifiers.
+//
+// For example:
+//
+// repeat! {
+//     ($name); X; Y:
+//     struct $name;
+// }
+//
+// Expands to:
+//
+// struct X; struct Y;
+//
+// This is used to repeat the tests using both the `N` and `Z`
+// types.
+macro_rules! repeat {
+    (($($dollar:tt $placeholder:ident)*); $($($values:ident),+);*: $($test:tt)*) => {
+        macro_rules! single {
+            ($($dollar $placeholder:ident),*) => { $($test)* }
+        }
+        $(single!($($values),+);)*
+    }
+}
+
+fn main() {
+    repeat! {
+        ($arr $Ty); n, N; z, Z:
+        compare_evaluation!({ let [_, x @ .., _] = $arr!(1, 2, 3, 4); x }, [$Ty; 2]);
+        compare_evaluation!({ let [_, ref x @ .., _] = $arr!(1, 2, 3, 4); x }, &'static [$Ty; 2]);
+        compare_evaluation!({ let [_, x @ .., _] = &$arr!(1, 2, 3, 4); x }, &'static [$Ty; 2]);
+
+        compare_evaluation!({ let [_, _, x @ .., _, _] = $arr!(1, 2, 3, 4); x }, [$Ty; 0]);
+        compare_evaluation!(
+            { let [_, _, ref x @ .., _, _] = $arr!(1, 2, 3, 4); x },
+            &'static [$Ty; 0],
+        );
+        compare_evaluation!(
+            { let [_, _, x @ .., _, _] = &$arr!(1, 2, 3, 4); x },
+            &'static [$Ty; 0],
+        );
+
+        compare_evaluation!({ let [_, .., x] = $arr!(1, 2, 3, 4); x }, $Ty);
+        compare_evaluation!({ let [_, .., ref x] = $arr!(1, 2, 3, 4); x }, &'static $Ty);
+        compare_evaluation!({ let [_, _y @ .., x] = &$arr!(1, 2, 3, 4); x }, &'static $Ty);
+    }
+
+    compare_evaluation!({ let [_, .., N(x)] = n!(1, 2, 3, 4); x }, u8);
+    compare_evaluation!({ let [_, .., N(ref x)] = n!(1, 2, 3, 4); x }, &'static u8);
+    compare_evaluation!({ let [_, .., N(x)] = &n!(1, 2, 3, 4); x }, &'static u8);
+
+    compare_evaluation!({ let [N(x), .., _] = n!(1, 2, 3, 4); x }, u8);
+    compare_evaluation!({ let [N(ref x), .., _] = n!(1, 2, 3, 4); x }, &'static u8);
+    compare_evaluation!({ let [N(x), .., _] = &n!(1, 2, 3, 4); x }, &'static u8);
+}
diff --git a/compiler/rustc_codegen_gcc/example/track-caller-attribute.rs b/compiler/rustc_codegen_gcc/example/track-caller-attribute.rs
new file mode 100644
index 00000000000..93bab17e46b
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/example/track-caller-attribute.rs
@@ -0,0 +1,40 @@
+// Based on https://github.com/anp/rust/blob/175631311716d7dfeceec40d2587cde7142ffa8c/src/test/ui/rfc-2091-track-caller/track-caller-attribute.rs
+
+// run-pass
+
+use std::panic::Location;
+
+#[track_caller]
+fn tracked() -> &'static Location<'static> {
+    Location::caller()
+}
+
+fn nested_intrinsic() -> &'static Location<'static> {
+    Location::caller()
+}
+
+fn nested_tracked() -> &'static Location<'static> {
+    tracked()
+}
+
+fn main() {
+    let location = Location::caller();
+    assert_eq!(location.file(), file!());
+    assert_eq!(location.line(), 21);
+    assert_eq!(location.column(), 20);
+
+    let tracked = tracked();
+    assert_eq!(tracked.file(), file!());
+    assert_eq!(tracked.line(), 26);
+    assert_eq!(tracked.column(), 19);
+
+    let nested = nested_intrinsic();
+    assert_eq!(nested.file(), file!());
+    assert_eq!(nested.line(), 13);
+    assert_eq!(nested.column(), 5);
+
+    let contained = nested_tracked();
+    assert_eq!(contained.file(), file!());
+    assert_eq!(contained.line(), 17);
+    assert_eq!(contained.column(), 5);
+}
diff --git a/compiler/rustc_codegen_gcc/patches/0022-core-Disable-not-compiling-tests.patch b/compiler/rustc_codegen_gcc/patches/0022-core-Disable-not-compiling-tests.patch
new file mode 100644
index 00000000000..aae62a938b4
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/patches/0022-core-Disable-not-compiling-tests.patch
@@ -0,0 +1,63 @@
+From f6befc4bb51d84f5f1cf35938a168c953d421350 Mon Sep 17 00:00:00 2001
+From: bjorn3 <bjorn3@users.noreply.github.com>
+Date: Sun, 24 Nov 2019 15:10:23 +0100
+Subject: [PATCH] [core] Disable not compiling tests
+
+---
+ library/core/tests/Cargo.toml         | 8 ++++++++
+ library/core/tests/num/flt2dec/mod.rs | 1 -
+ library/core/tests/num/int_macros.rs  | 2 ++
+ library/core/tests/num/uint_macros.rs | 2 ++
+ library/core/tests/ptr.rs             | 2 ++
+ library/core/tests/slice.rs           | 2 ++
+ 6 files changed, 16 insertions(+), 1 deletion(-)
+ create mode 100644 library/core/tests/Cargo.toml
+
+diff --git a/library/core/tests/Cargo.toml b/library/core/tests/Cargo.toml
+new file mode 100644
+index 0000000..46fd999
+--- /dev/null
++++ b/library/core/tests/Cargo.toml
+@@ -0,0 +1,8 @@
++[package]
++name = "core"
++version = "0.0.0"
++edition = "2018"
++
++[lib]
++name = "coretests"
++path = "lib.rs"
+diff --git a/library/core/tests/num/flt2dec/mod.rs b/library/core/tests/num/flt2dec/mod.rs
+index a35897e..f0bf645 100644
+--- a/library/core/tests/num/flt2dec/mod.rs
++++ b/library/core/tests/num/flt2dec/mod.rs
+@@ -13,7 +13,6 @@ mod strategy {
+     mod dragon;
+     mod grisu;
+ }
+-mod random;
+ 
+ pub fn decode_finite<T: DecodableFloat>(v: T) -> Decoded {
+     match decode(v).1 {
+diff --git a/library/core/tests/slice.rs b/library/core/tests/slice.rs
+index 6609bc3..241b497 100644
+--- a/library/core/tests/slice.rs
++++ b/library/core/tests/slice.rs
+@@ -1209,6 +1209,7 @@ fn brute_force_rotate_test_1() {
+     }
+ }
+ 
++/*
+ #[test]
+ #[cfg(not(target_arch = "wasm32"))]
+ fn sort_unstable() {
+@@ -1394,6 +1395,7 @@ fn partition_at_index() {
+     v.select_nth_unstable(0);
+     assert!(v == [0xDEADBEEF]);
+ }
++*/
+ 
+ #[test]
+ #[should_panic(expected = "index 0 greater than length of slice")]
+--
+2.21.0 (Apple Git-122)
diff --git a/compiler/rustc_codegen_gcc/patches/0023-core-Ignore-failing-tests.patch b/compiler/rustc_codegen_gcc/patches/0023-core-Ignore-failing-tests.patch
new file mode 100644
index 00000000000..ee5ba449fb8
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/patches/0023-core-Ignore-failing-tests.patch
@@ -0,0 +1,49 @@
+From dd82e95c9de212524e14fc60155de1ae40156dfc Mon Sep 17 00:00:00 2001
+From: bjorn3 <bjorn3@users.noreply.github.com>
+Date: Sun, 24 Nov 2019 15:34:06 +0100
+Subject: [PATCH] [core] Ignore failing tests
+
+---
+ library/core/tests/iter.rs       |  4 ++++
+ library/core/tests/num/bignum.rs | 10 ++++++++++
+ library/core/tests/num/mod.rs    |  5 +++--
+ library/core/tests/time.rs       |  1 +
+ 4 files changed, 18 insertions(+), 2 deletions(-)
+
+diff --git a/library/core/tests/array.rs b/library/core/tests/array.rs
+index 4bc44e9..8e3c7a4 100644
+--- a/library/core/tests/array.rs
++++ b/library/core/tests/array.rs
+@@ -242,6 +242,7 @@ fn iterator_drops() {
+     assert_eq!(i.get(), 5);
+ }
+ 
++/*
+ // This test does not work on targets without panic=unwind support.
+ // To work around this problem, test is marked is should_panic, so it will
+ // be automagically skipped on unsuitable targets, such as
+@@ -283,6 +284,7 @@ fn array_default_impl_avoids_leaks_on_panic() {
+     assert_eq!(COUNTER.load(Relaxed), 0);
+     panic!("test succeeded")
+ }
++*/
+ 
+ #[test]
+ fn empty_array_is_always_default() {
+@@ -304,6 +304,7 @@ fn array_map() {
+     assert_eq!(b, [1, 2, 3]);
+ }
+ 
++/*
+ // See note on above test for why `should_panic` is used.
+ #[test]
+ #[should_panic(expected = "test succeeded")]
+@@ -332,6 +333,7 @@ fn array_map_drop_safety() {
+     assert_eq!(DROPPED.load(Ordering::SeqCst), num_to_create);
+     panic!("test succeeded")
+ }
++*/
+ 
+ #[test]
+ fn cell_allows_array_cycle() {
+-- 2.21.0 (Apple Git-122)
diff --git a/compiler/rustc_codegen_gcc/prepare.sh b/compiler/rustc_codegen_gcc/prepare.sh
new file mode 100755
index 00000000000..503fa29b362
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/prepare.sh
@@ -0,0 +1,22 @@
+#!/bin/bash --verbose
+set -e
+
+source prepare_build.sh
+
+cargo install hyperfine || echo "Skipping hyperfine install"
+
+git clone https://github.com/rust-lang/regex.git || echo "rust-lang/regex has already been cloned"
+pushd regex
+git checkout -- .
+git checkout 341f207c1071f7290e3f228c710817c280c8dca1
+popd
+
+git clone https://github.com/ebobby/simple-raytracer || echo "ebobby/simple-raytracer has already been cloned"
+pushd simple-raytracer
+git checkout -- .
+git checkout 804a7a21b9e673a482797aa289a18ed480e4d813
+
+# build with cg_llvm for perf comparison
+cargo build
+mv target/debug/main raytracer_cg_llvm
+popd
diff --git a/compiler/rustc_codegen_gcc/prepare_build.sh b/compiler/rustc_codegen_gcc/prepare_build.sh
new file mode 100755
index 00000000000..ccf53509830
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/prepare_build.sh
@@ -0,0 +1,5 @@
+#!/bin/bash --verbose
+set -e
+
+rustup component add rust-src rustc-dev llvm-tools-preview
+./build_sysroot/prepare_sysroot_src.sh
diff --git a/compiler/rustc_codegen_gcc/rust-toolchain b/compiler/rustc_codegen_gcc/rust-toolchain
new file mode 100644
index 00000000000..d311a33f807
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/rust-toolchain
@@ -0,0 +1 @@
+nightly-2021-09-28
diff --git a/compiler/rustc_codegen_gcc/rustup.sh b/compiler/rustc_codegen_gcc/rustup.sh
new file mode 100755
index 00000000000..01ce5bb78be
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/rustup.sh
@@ -0,0 +1,29 @@
+#!/bin/bash
+
+set -e
+
+case $1 in
+    "prepare")
+        TOOLCHAIN=$(date +%Y-%m-%d)
+
+        echo "=> Installing new nightly"
+        rustup toolchain install --profile minimal nightly-${TOOLCHAIN} # Sanity check to see if the nightly exists
+        echo nightly-${TOOLCHAIN} > rust-toolchain
+
+        echo "=> Uninstalling all old nighlies"
+        for nightly in $(rustup toolchain list | grep nightly | grep -v $TOOLCHAIN | grep -v nightly-x86_64); do
+            rustup toolchain uninstall $nightly
+        done
+
+        ./clean_all.sh
+        ./prepare.sh
+        ;;
+    "commit")
+        git add rust-toolchain
+        git commit -m "Rustup to $(rustc -V)"
+        ;;
+    *)
+        echo "Unknown command '$1'"
+        echo "Usage: ./rustup.sh prepare|commit"
+        ;;
+esac
diff --git a/compiler/rustc_codegen_gcc/src/abi.rs b/compiler/rustc_codegen_gcc/src/abi.rs
new file mode 100644
index 00000000000..ce428c589a4
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/abi.rs
@@ -0,0 +1,160 @@
+use gccjit::{ToRValue, Type};
+use rustc_codegen_ssa::traits::{AbiBuilderMethods, BaseTypeMethods};
+use rustc_middle::bug;
+use rustc_middle::ty::Ty;
+use rustc_target::abi::call::{CastTarget, FnAbi, PassMode, Reg, RegKind};
+
+use crate::builder::Builder;
+use crate::context::CodegenCx;
+use crate::intrinsic::ArgAbiExt;
+use crate::type_of::LayoutGccExt;
+
+impl<'a, 'gcc, 'tcx> AbiBuilderMethods<'tcx> for Builder<'a, 'gcc, 'tcx> {
+    fn apply_attrs_callsite(&mut self, _fn_abi: &FnAbi<'tcx, Ty<'tcx>>, _callsite: Self::Value) {
+        // TODO(antoyo)
+    }
+
+    fn get_param(&self, index: usize) -> Self::Value {
+        self.cx.current_func.borrow().expect("current func")
+            .get_param(index as i32)
+            .to_rvalue()
+    }
+}
+
+impl GccType for CastTarget {
+    fn gcc_type<'gcc>(&self, cx: &CodegenCx<'gcc, '_>) -> Type<'gcc> {
+        let rest_gcc_unit = self.rest.unit.gcc_type(cx);
+        let (rest_count, rem_bytes) =
+            if self.rest.unit.size.bytes() == 0 {
+                (0, 0)
+            }
+            else {
+                (self.rest.total.bytes() / self.rest.unit.size.bytes(), self.rest.total.bytes() % self.rest.unit.size.bytes())
+            };
+
+        if self.prefix.iter().all(|x| x.is_none()) {
+            // Simplify to a single unit when there is no prefix and size <= unit size
+            if self.rest.total <= self.rest.unit.size {
+                return rest_gcc_unit;
+            }
+
+            // Simplify to array when all chunks are the same size and type
+            if rem_bytes == 0 {
+                return cx.type_array(rest_gcc_unit, rest_count);
+            }
+        }
+
+        // Create list of fields in the main structure
+        let mut args: Vec<_> = self
+            .prefix
+            .iter()
+            .flat_map(|option_kind| {
+                option_kind.map(|kind| Reg { kind, size: self.prefix_chunk_size }.gcc_type(cx))
+            })
+            .chain((0..rest_count).map(|_| rest_gcc_unit))
+            .collect();
+
+        // Append final integer
+        if rem_bytes != 0 {
+            // Only integers can be really split further.
+            assert_eq!(self.rest.unit.kind, RegKind::Integer);
+            args.push(cx.type_ix(rem_bytes * 8));
+        }
+
+        cx.type_struct(&args, false)
+    }
+}
+
+pub trait GccType {
+    fn gcc_type<'gcc>(&self, cx: &CodegenCx<'gcc, '_>) -> Type<'gcc>;
+}
+
+impl GccType for Reg {
+    fn gcc_type<'gcc>(&self, cx: &CodegenCx<'gcc, '_>) -> Type<'gcc> {
+        match self.kind {
+            RegKind::Integer => cx.type_ix(self.size.bits()),
+            RegKind::Float => {
+                match self.size.bits() {
+                    32 => cx.type_f32(),
+                    64 => cx.type_f64(),
+                    _ => bug!("unsupported float: {:?}", self),
+                }
+            },
+            RegKind::Vector => unimplemented!(), //cx.type_vector(cx.type_i8(), self.size.bytes()),
+        }
+    }
+}
+
+pub trait FnAbiGccExt<'gcc, 'tcx> {
+    // TODO(antoyo): return a function pointer type instead?
+    fn gcc_type(&self, cx: &CodegenCx<'gcc, 'tcx>) -> (Type<'gcc>, Vec<Type<'gcc>>, bool);
+    fn ptr_to_gcc_type(&self, cx: &CodegenCx<'gcc, 'tcx>) -> Type<'gcc>;
+}
+
+impl<'gcc, 'tcx> FnAbiGccExt<'gcc, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
+    fn gcc_type(&self, cx: &CodegenCx<'gcc, 'tcx>) -> (Type<'gcc>, Vec<Type<'gcc>>, bool) {
+        let args_capacity: usize = self.args.iter().map(|arg|
+            if arg.pad.is_some() {
+                1
+            }
+            else {
+                0
+            } +
+            if let PassMode::Pair(_, _) = arg.mode {
+                2
+            } else {
+                1
+            }
+        ).sum();
+        let mut argument_tys = Vec::with_capacity(
+            if let PassMode::Indirect { .. } = self.ret.mode {
+                1
+            }
+            else {
+                0
+            } + args_capacity,
+        );
+
+        let return_ty =
+            match self.ret.mode {
+                PassMode::Ignore => cx.type_void(),
+                PassMode::Direct(_) | PassMode::Pair(..) => self.ret.layout.immediate_gcc_type(cx),
+                PassMode::Cast(cast) => cast.gcc_type(cx),
+                PassMode::Indirect { .. } => {
+                    argument_tys.push(cx.type_ptr_to(self.ret.memory_ty(cx)));
+                    cx.type_void()
+                }
+            };
+
+        for arg in &self.args {
+            // add padding
+            if let Some(ty) = arg.pad {
+                argument_tys.push(ty.gcc_type(cx));
+            }
+
+            let arg_ty = match arg.mode {
+                PassMode::Ignore => continue,
+                PassMode::Direct(_) => arg.layout.immediate_gcc_type(cx),
+                PassMode::Pair(..) => {
+                    argument_tys.push(arg.layout.scalar_pair_element_gcc_type(cx, 0, true));
+                    argument_tys.push(arg.layout.scalar_pair_element_gcc_type(cx, 1, true));
+                    continue;
+                }
+                PassMode::Indirect { extra_attrs: Some(_), .. } => {
+                    unimplemented!();
+                }
+                PassMode::Cast(cast) => cast.gcc_type(cx),
+                PassMode::Indirect { extra_attrs: None, .. } => cx.type_ptr_to(arg.memory_ty(cx)),
+            };
+            argument_tys.push(arg_ty);
+        }
+
+        (return_ty, argument_tys, self.c_variadic)
+    }
+
+    fn ptr_to_gcc_type(&self, cx: &CodegenCx<'gcc, 'tcx>) -> Type<'gcc> {
+        let (return_type, params, variadic) = self.gcc_type(cx);
+        let pointer_type = cx.context.new_function_pointer_type(None, return_type, &params, variadic);
+        pointer_type
+    }
+}
diff --git a/compiler/rustc_codegen_gcc/src/allocator.rs b/compiler/rustc_codegen_gcc/src/allocator.rs
new file mode 100644
index 00000000000..6378a31202c
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/allocator.rs
@@ -0,0 +1,116 @@
+use gccjit::{FunctionType, ToRValue};
+use rustc_ast::expand::allocator::{AllocatorKind, AllocatorTy, ALLOCATOR_METHODS};
+use rustc_middle::bug;
+use rustc_middle::ty::TyCtxt;
+use rustc_span::symbol::sym;
+
+use crate::GccContext;
+
+pub(crate) unsafe fn codegen(tcx: TyCtxt<'_>, mods: &mut GccContext, _module_name: &str, kind: AllocatorKind, has_alloc_error_handler: bool) {
+    let context = &mods.context;
+    let usize =
+        match tcx.sess.target.pointer_width {
+            16 => context.new_type::<u16>(),
+            32 => context.new_type::<u32>(),
+            64 => context.new_type::<u64>(),
+            tws => bug!("Unsupported target word size for int: {}", tws),
+        };
+    let i8 = context.new_type::<i8>();
+    let i8p = i8.make_pointer();
+    let void = context.new_type::<()>();
+
+    for method in ALLOCATOR_METHODS {
+        let mut types = Vec::with_capacity(method.inputs.len());
+        for ty in method.inputs.iter() {
+            match *ty {
+                AllocatorTy::Layout => {
+                    types.push(usize);
+                    types.push(usize);
+                }
+                AllocatorTy::Ptr => types.push(i8p),
+                AllocatorTy::Usize => types.push(usize),
+
+                AllocatorTy::ResultPtr | AllocatorTy::Unit => panic!("invalid allocator arg"),
+            }
+        }
+        let output = match method.output {
+            AllocatorTy::ResultPtr => Some(i8p),
+            AllocatorTy::Unit => None,
+
+            AllocatorTy::Layout | AllocatorTy::Usize | AllocatorTy::Ptr => {
+                panic!("invalid allocator output")
+            }
+        };
+        let name = format!("__rust_{}", method.name);
+
+        let args: Vec<_> = types.iter().enumerate()
+            .map(|(index, typ)| context.new_parameter(None, *typ, &format!("param{}", index)))
+            .collect();
+        let func = context.new_function(None, FunctionType::Exported, output.unwrap_or(void), &args, name, false);
+
+        if tcx.sess.target.options.default_hidden_visibility {
+            // TODO(antoyo): set visibility.
+        }
+        if tcx.sess.must_emit_unwind_tables() {
+            // TODO(antoyo): emit unwind tables.
+        }
+
+        let callee = kind.fn_name(method.name);
+        let args: Vec<_> = types.iter().enumerate()
+            .map(|(index, typ)| context.new_parameter(None, *typ, &format!("param{}", index)))
+            .collect();
+        let callee = context.new_function(None, FunctionType::Extern, output.unwrap_or(void), &args, callee, false);
+        // TODO(antoyo): set visibility.
+
+        let block = func.new_block("entry");
+
+        let args = args
+            .iter()
+            .enumerate()
+            .map(|(i, _)| func.get_param(i as i32).to_rvalue())
+            .collect::<Vec<_>>();
+        let ret = context.new_call(None, callee, &args);
+        //llvm::LLVMSetTailCall(ret, True);
+        if output.is_some() {
+            block.end_with_return(None, ret);
+        }
+        else {
+            block.end_with_void_return(None);
+        }
+
+        // TODO(@Commeownist): Check if we need to emit some extra debugging info in certain circumstances
+        // as described in https://github.com/rust-lang/rust/commit/77a96ed5646f7c3ee8897693decc4626fe380643
+    }
+
+    let types = [usize, usize];
+    let name = "__rust_alloc_error_handler".to_string();
+    let args: Vec<_> = types.iter().enumerate()
+        .map(|(index, typ)| context.new_parameter(None, *typ, &format!("param{}", index)))
+        .collect();
+    let func = context.new_function(None, FunctionType::Exported, void, &args, name, false);
+
+    let kind =
+        if has_alloc_error_handler {
+            AllocatorKind::Global
+        }
+        else {
+            AllocatorKind::Default
+        };
+    let callee = kind.fn_name(sym::oom);
+    let args: Vec<_> = types.iter().enumerate()
+        .map(|(index, typ)| context.new_parameter(None, *typ, &format!("param{}", index)))
+        .collect();
+    let callee = context.new_function(None, FunctionType::Extern, void, &args, callee, false);
+    //llvm::LLVMRustSetVisibility(callee, llvm::Visibility::Hidden);
+
+    let block = func.new_block("entry");
+
+    let args = args
+        .iter()
+        .enumerate()
+        .map(|(i, _)| func.get_param(i as i32).to_rvalue())
+        .collect::<Vec<_>>();
+    let _ret = context.new_call(None, callee, &args);
+    //llvm::LLVMSetTailCall(ret, True);
+    block.end_with_void_return(None);
+}
diff --git a/compiler/rustc_codegen_gcc/src/archive.rs b/compiler/rustc_codegen_gcc/src/archive.rs
new file mode 100644
index 00000000000..d749d763402
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/archive.rs
@@ -0,0 +1,218 @@
+use std::fs::File;
+use std::path::{Path, PathBuf};
+
+use rustc_session::Session;
+use rustc_codegen_ssa::back::archive::ArchiveBuilder;
+
+use rustc_data_structures::temp_dir::MaybeTempDir;
+use rustc_middle::middle::cstore::DllImport;
+
+
+struct ArchiveConfig<'a> {
+    sess: &'a Session,
+    dst: PathBuf,
+    use_native_ar: bool,
+    use_gnu_style_archive: bool,
+}
+
+#[derive(Debug)]
+enum ArchiveEntry {
+    FromArchive {
+        archive_index: usize,
+        entry_index: usize,
+    },
+    File(PathBuf),
+}
+
+pub struct ArArchiveBuilder<'a> {
+    config: ArchiveConfig<'a>,
+    src_archives: Vec<(PathBuf, ar::Archive<File>)>,
+    // Don't use `HashMap` here, as the order is important. `rust.metadata.bin` must always be at
+    // the end of an archive for linkers to not get confused.
+    entries: Vec<(String, ArchiveEntry)>,
+}
+
+impl<'a> ArchiveBuilder<'a> for ArArchiveBuilder<'a> {
+    fn new(sess: &'a Session, output: &Path, input: Option<&Path>) -> Self {
+        let config = ArchiveConfig {
+            sess,
+            dst: output.to_path_buf(),
+            use_native_ar: false,
+            // FIXME test for linux and System V derivatives instead
+            use_gnu_style_archive: sess.target.options.archive_format == "gnu",
+        };
+
+        let (src_archives, entries) = if let Some(input) = input {
+            let mut archive = ar::Archive::new(File::open(input).unwrap());
+            let mut entries = Vec::new();
+
+            let mut i = 0;
+            while let Some(entry) = archive.next_entry() {
+                let entry = entry.unwrap();
+                entries.push((
+                    String::from_utf8(entry.header().identifier().to_vec()).unwrap(),
+                    ArchiveEntry::FromArchive {
+                        archive_index: 0,
+                        entry_index: i,
+                    },
+                ));
+                i += 1;
+            }
+
+            (vec![(input.to_owned(), archive)], entries)
+        } else {
+            (vec![], Vec::new())
+        };
+
+        ArArchiveBuilder {
+            config,
+            src_archives,
+            entries,
+        }
+    }
+
+    fn src_files(&mut self) -> Vec<String> {
+        self.entries.iter().map(|(name, _)| name.clone()).collect()
+    }
+
+    fn remove_file(&mut self, name: &str) {
+        let index = self
+            .entries
+            .iter()
+            .position(|(entry_name, _)| entry_name == name)
+            .expect("Tried to remove file not existing in src archive");
+        self.entries.remove(index);
+    }
+
+    fn add_file(&mut self, file: &Path) {
+        self.entries.push((
+            file.file_name().unwrap().to_str().unwrap().to_string(),
+            ArchiveEntry::File(file.to_owned()),
+        ));
+    }
+
+    fn add_archive<F>(&mut self, archive_path: &Path, mut skip: F) -> std::io::Result<()>
+    where
+        F: FnMut(&str) -> bool + 'static,
+    {
+        let mut archive = ar::Archive::new(std::fs::File::open(&archive_path)?);
+        let archive_index = self.src_archives.len();
+
+        let mut i = 0;
+        while let Some(entry) = archive.next_entry() {
+            let entry = entry?;
+            let file_name = String::from_utf8(entry.header().identifier().to_vec())
+                .map_err(|err| std::io::Error::new(std::io::ErrorKind::InvalidData, err))?;
+            if !skip(&file_name) {
+                self.entries
+                    .push((file_name, ArchiveEntry::FromArchive { archive_index, entry_index: i }));
+            }
+            i += 1;
+        }
+
+        self.src_archives.push((archive_path.to_owned(), archive));
+        Ok(())
+    }
+
+    fn update_symbols(&mut self) {
+    }
+
+    fn build(mut self) {
+        use std::process::Command;
+
+        fn add_file_using_ar(archive: &Path, file: &Path) {
+            Command::new("ar")
+                .arg("r") // add or replace file
+                .arg("-c") // silence created file message
+                .arg(archive)
+                .arg(&file)
+                .status()
+                .unwrap();
+        }
+
+        enum BuilderKind<'a> {
+            Bsd(ar::Builder<File>),
+            Gnu(ar::GnuBuilder<File>),
+            NativeAr(&'a Path),
+        }
+
+        let mut builder = if self.config.use_native_ar {
+            BuilderKind::NativeAr(&self.config.dst)
+        } else if self.config.use_gnu_style_archive {
+            BuilderKind::Gnu(ar::GnuBuilder::new(
+                File::create(&self.config.dst).unwrap(),
+                self.entries
+                    .iter()
+                    .map(|(name, _)| name.as_bytes().to_vec())
+                    .collect(),
+            ))
+        } else {
+            BuilderKind::Bsd(ar::Builder::new(File::create(&self.config.dst).unwrap()))
+        };
+
+        // Add all files
+        for (entry_name, entry) in self.entries.into_iter() {
+            match entry {
+                ArchiveEntry::FromArchive {
+                    archive_index,
+                    entry_index,
+                } => {
+                    let (ref src_archive_path, ref mut src_archive) =
+                        self.src_archives[archive_index];
+                    let entry = src_archive.jump_to_entry(entry_index).unwrap();
+                    let header = entry.header().clone();
+
+                    match builder {
+                        BuilderKind::Bsd(ref mut builder) => {
+                            builder.append(&header, entry).unwrap()
+                        }
+                        BuilderKind::Gnu(ref mut builder) => {
+                            builder.append(&header, entry).unwrap()
+                        }
+                        BuilderKind::NativeAr(archive_file) => {
+                            Command::new("ar")
+                                .arg("x")
+                                .arg(src_archive_path)
+                                .arg(&entry_name)
+                                .status()
+                                .unwrap();
+                            add_file_using_ar(archive_file, Path::new(&entry_name));
+                            std::fs::remove_file(entry_name).unwrap();
+                        }
+                    }
+                }
+                ArchiveEntry::File(file) =>
+                    match builder {
+                        BuilderKind::Bsd(ref mut builder) => {
+                            builder
+                                .append_file(entry_name.as_bytes(), &mut File::open(file).expect("file for bsd builder"))
+                                .unwrap()
+                        },
+                        BuilderKind::Gnu(ref mut builder) => {
+                            builder
+                                .append_file(entry_name.as_bytes(), &mut File::open(&file).expect(&format!("file {:?} for gnu builder", file)))
+                                .unwrap()
+                        },
+                        BuilderKind::NativeAr(archive_file) => add_file_using_ar(archive_file, &file),
+                    },
+            }
+        }
+
+        // Finalize archive
+        std::mem::drop(builder);
+
+        // Run ranlib to be able to link the archive
+        let status = std::process::Command::new("ranlib")
+            .arg(self.config.dst)
+            .status()
+            .expect("Couldn't run ranlib");
+
+        if !status.success() {
+            self.config.sess.fatal(&format!("Ranlib exited with code {:?}", status.code()));
+        }
+    }
+
+    fn inject_dll_import_lib(&mut self, _lib_name: &str, _dll_imports: &[DllImport], _tmpdir: &MaybeTempDir) {
+        unimplemented!();
+    }
+}
diff --git a/compiler/rustc_codegen_gcc/src/asm.rs b/compiler/rustc_codegen_gcc/src/asm.rs
new file mode 100644
index 00000000000..3b77097e9ad
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/asm.rs
@@ -0,0 +1,785 @@
+use gccjit::{LValue, RValue, ToRValue, Type};
+use rustc_ast::ast::{InlineAsmOptions, InlineAsmTemplatePiece};
+use rustc_codegen_ssa::mir::operand::OperandValue;
+use rustc_codegen_ssa::mir::place::PlaceRef;
+use rustc_codegen_ssa::traits::{AsmBuilderMethods, AsmMethods, BaseTypeMethods, BuilderMethods, GlobalAsmOperandRef, InlineAsmOperandRef};
+
+use rustc_hir::LlvmInlineAsmInner;
+use rustc_middle::{bug, ty::Instance};
+use rustc_span::{Span, Symbol};
+use rustc_target::asm::*;
+
+use std::borrow::Cow;
+
+use crate::builder::Builder;
+use crate::context::CodegenCx;
+use crate::type_of::LayoutGccExt;
+
+
+// Rust asm! and GCC Extended Asm semantics differ substantially.
+//
+// 1. Rust asm operands go along as one list of operands. Operands themselves indicate 
+//    if they're "in" or "out". "In" and "out" operands can interleave. One operand can be 
+//    both "in" and "out" (`inout(reg)`).
+//
+//    GCC asm has two different lists for "in" and "out" operands. In terms of gccjit, 
+//    this means that all "out" operands must go before "in" operands. "In" and "out" operands 
+//    cannot interleave.
+//
+// 2. Operand lists in both Rust and GCC are indexed. Index starts from 0. Indexes are important 
+//    because the asm template refers to operands by index.
+//
+//    Mapping from Rust to GCC index would be 1-1 if it wasn't for...
+//
+// 3. Clobbers. GCC has a separate list of clobbers, and clobbers don't have indexes. 
+//    Contrary, Rust expresses clobbers through "out" operands that aren't tied to 
+//    a variable (`_`),  and such "clobbers" do have index.
+//
+// 4. Furthermore, GCC Extended Asm does not support explicit register constraints 
+//    (like `out("eax")`) directly, offering so-called "local register variables" 
+//    as a workaround. These variables need to be declared and initialized *before* 
+//    the Extended Asm block but *after* normal local variables 
+//    (see comment in `codegen_inline_asm` for explanation).
+//
+// With that in mind, let's see how we translate Rust syntax to GCC 
+// (from now on, `CC` stands for "constraint code"):
+//
+// * `out(reg_class) var`   -> translated to output operand: `"=CC"(var)`
+// * `inout(reg_class) var` -> translated to output operand: `"+CC"(var)`
+// * `in(reg_class) var`    -> translated to input operand: `"CC"(var)`
+//
+// * `out(reg_class) _` -> translated to one `=r(tmp)`, where "tmp" is a temporary unused variable
+//
+// * `out("explicit register") _` -> not translated to any operands, register is simply added to clobbers list
+//
+// * `inout(reg_class) in_var => out_var` -> translated to two operands: 
+//                              output: `"=CC"(in_var)`
+//                              input:  `"num"(out_var)` where num is the GCC index 
+//                                       of the corresponding output operand
+//
+// * `inout(reg_class) in_var => _` -> same as `inout(reg_class) in_var => tmp`, 
+//                                      where "tmp" is a temporary unused variable
+//
+// * `out/in/inout("explicit register") var` -> translated to one or two operands as described above 
+//                                              with `"r"(var)` constraint, 
+//                                              and one register variable assigned to the desired register.
+// 
+
+const ATT_SYNTAX_INS: &str = ".att_syntax noprefix\n\t";
+const INTEL_SYNTAX_INS: &str = "\n\t.intel_syntax noprefix";
+
+
+struct AsmOutOperand<'a, 'tcx, 'gcc> {
+    rust_idx: usize,
+    constraint: &'a str,
+    late: bool,
+    readwrite: bool,
+
+    tmp_var: LValue<'gcc>,
+    out_place: Option<PlaceRef<'tcx, RValue<'gcc>>>
+}
+
+struct AsmInOperand<'a, 'tcx> {
+    rust_idx: usize,
+    constraint: Cow<'a, str>,
+    val: RValue<'tcx>
+}
+
+impl AsmOutOperand<'_, '_, '_> {
+    fn to_constraint(&self) -> String {
+        let mut res = String::with_capacity(self.constraint.len() + self.late as usize + 1);
+
+        let sign = if self.readwrite { '+' } else { '=' };
+        res.push(sign);
+        if !self.late {
+            res.push('&');
+        }
+
+        res.push_str(&self.constraint);
+        res
+    }
+}
+
+enum ConstraintOrRegister {
+    Constraint(&'static str),
+    Register(&'static str)
+}
+
+
+impl<'a, 'gcc, 'tcx> AsmBuilderMethods<'tcx> for Builder<'a, 'gcc, 'tcx> {
+    fn codegen_llvm_inline_asm(&mut self, _ia: &LlvmInlineAsmInner, _outputs: Vec<PlaceRef<'tcx, RValue<'gcc>>>, _inputs: Vec<RValue<'gcc>>, span: Span) -> bool {
+        self.sess().struct_span_err(span, "GCC backend does not support `llvm_asm!`")
+            .help("consider using the `asm!` macro instead")
+            .emit();
+
+        // We return `true` even if we've failed to generate the asm
+        // because we want to suppress the "malformed inline assembly" error
+        // generated by the frontend.
+        true
+    }
+
+    fn codegen_inline_asm(&mut self, template: &[InlineAsmTemplatePiece], rust_operands: &[InlineAsmOperandRef<'tcx, Self>], options: InlineAsmOptions, _span: &[Span]) {
+        let asm_arch = self.tcx.sess.asm_arch.unwrap();
+        let is_x86 = matches!(asm_arch, InlineAsmArch::X86 | InlineAsmArch::X86_64);
+        let att_dialect = is_x86 && options.contains(InlineAsmOptions::ATT_SYNTAX);
+        let intel_dialect = is_x86 && !options.contains(InlineAsmOptions::ATT_SYNTAX);
+
+        // GCC index of an output operand equals its position in the array 
+        let mut outputs = vec![];
+
+        // GCC index of an input operand equals its position in the array
+        // added to `outputs.len()`
+        let mut inputs = vec![];
+
+        // Clobbers collected from `out("explicit register") _` and `inout("expl_reg") var => _`
+        let mut clobbers = vec![];
+
+        // We're trying to preallocate space for the template
+        let mut constants_len = 0;
+
+        // There are rules we must adhere to if we want GCC to do the right thing:
+        // 
+        // * Every local variable that the asm block uses as an output must be declared *before*
+        //   the asm block. 
+        // * There must be no instructions whatsoever between the register variables and the asm.
+        //
+        // Therefore, the backend must generate the instructions strictly in this order:
+        //
+        // 1. Output variables.
+        // 2. Register variables.
+        // 3. The asm block.
+        //
+        // We also must make sure that no input operands are emitted before output operands.
+        //
+        // This is why we work in passes, first emitting local vars, then local register vars.
+        // Also, we don't emit any asm operands immediately; we save them to 
+        // the one of the buffers to be emitted later.
+
+        // 1. Normal variables (and saving operands to buffers).
+        for (rust_idx, op) in rust_operands.iter().enumerate() {
+            match *op {
+                InlineAsmOperandRef::Out { reg, late, place } => {
+                    use ConstraintOrRegister::*;
+
+                    let (constraint, ty) = match (reg_to_gcc(reg), place) {
+                        (Constraint(constraint), Some(place)) => (constraint, place.layout.gcc_type(self.cx, false)),
+                        // When `reg` is a class and not an explicit register but the out place is not specified,
+                        // we need to create an unused output variable to assign the output to. This var
+                        // needs to be of a type that's "compatible" with the register class, but specific type 
+                        // doesn't matter.
+                        (Constraint(constraint), None) => (constraint, dummy_output_type(self.cx, reg.reg_class())),
+                        (Register(_), Some(_)) => {
+                            // left for the next pass
+                            continue
+                        },
+                        (Register(reg_name), None) => {
+                            // `clobber_abi` can add lots of clobbers that are not supported by the target,
+                            // such as AVX-512 registers, so we just ignore unsupported registers
+                            let is_target_supported = reg.reg_class().supported_types(asm_arch).iter()
+                                .any(|&(_, feature)| {
+                                    if let Some(feature) = feature {
+                                        self.tcx.sess.target_features.contains(&Symbol::intern(feature))
+                                    } else {
+                                        true // Register class is unconditionally supported
+                                    }
+                                });
+
+                            if is_target_supported && !clobbers.contains(&reg_name) {
+                                clobbers.push(reg_name);
+                            }
+                            continue
+                        }
+                    };
+
+                    let tmp_var = self.current_func().new_local(None, ty, "output_register");
+                    outputs.push(AsmOutOperand {
+                        constraint, 
+                        rust_idx,
+                        late,
+                        readwrite: false,
+                        tmp_var,
+                        out_place: place
+                    });
+                }
+
+                InlineAsmOperandRef::In { reg, value } => {
+                    if let ConstraintOrRegister::Constraint(constraint) = reg_to_gcc(reg) {
+                        inputs.push(AsmInOperand { 
+                            constraint: Cow::Borrowed(constraint), 
+                            rust_idx, 
+                            val: value.immediate()
+                        });
+                    } 
+                    else {
+                        // left for the next pass
+                        continue
+                    }
+                }
+
+                InlineAsmOperandRef::InOut { reg, late, in_value, out_place } => {
+                    let constraint = if let ConstraintOrRegister::Constraint(constraint) = reg_to_gcc(reg) {
+                        constraint
+                    } 
+                    else {
+                        // left for the next pass
+                        continue
+                    };
+
+                    // Rustc frontend guarantees that input and output types are "compatible",
+                    // so we can just use input var's type for the output variable.
+                    //
+                    // This decision is also backed by the fact that LLVM needs in and out 
+                    // values to be of *exactly the same type*, not just "compatible". 
+                    // I'm not sure if GCC is so picky too, but better safe than sorry.
+                    let ty = in_value.layout.gcc_type(self.cx, false);
+                    let tmp_var = self.current_func().new_local(None, ty, "output_register");
+
+                    // If the out_place is None (i.e `inout(reg) _` syntax was used), we translate
+                    // it to one "readwrite (+) output variable", otherwise we translate it to two 
+                    // "out and tied in" vars as described above.
+                    let readwrite = out_place.is_none();
+                    outputs.push(AsmOutOperand {
+                        constraint, 
+                        rust_idx,
+                        late,
+                        readwrite,
+                        tmp_var, 
+                        out_place,
+                    });
+
+                    if !readwrite {
+                        let out_gcc_idx = outputs.len() - 1;
+                        let constraint = Cow::Owned(out_gcc_idx.to_string());
+
+                        inputs.push(AsmInOperand {
+                            constraint, 
+                            rust_idx, 
+                            val: in_value.immediate()
+                        });
+                    }
+                }
+
+                InlineAsmOperandRef::Const { ref string } => {
+                    constants_len += string.len() + att_dialect as usize;
+                }
+
+                InlineAsmOperandRef::SymFn { instance } => {
+                    constants_len += self.tcx.symbol_name(instance).name.len();
+                }
+                InlineAsmOperandRef::SymStatic { def_id } => {
+                    constants_len += self.tcx.symbol_name(Instance::mono(self.tcx, def_id)).name.len();
+                }
+            }
+        }
+
+        // 2. Register variables.
+        for (rust_idx, op) in rust_operands.iter().enumerate() {
+            match *op {
+                // `out("explicit register") var`
+                InlineAsmOperandRef::Out { reg, late, place } => {
+                    if let ConstraintOrRegister::Register(reg_name) = reg_to_gcc(reg) {
+                        let out_place = if let Some(place) = place {
+                            place
+                        } 
+                        else {
+                            // processed in the previous pass
+                            continue
+                        };
+
+                        let ty = out_place.layout.gcc_type(self.cx, false);
+                        let tmp_var = self.current_func().new_local(None, ty, "output_register");
+                        tmp_var.set_register_name(reg_name);
+
+                        outputs.push(AsmOutOperand {
+                            constraint: "r".into(), 
+                            rust_idx,
+                            late,
+                            readwrite: false,
+                            tmp_var,
+                            out_place: Some(out_place)
+                        });
+                    }
+
+                    // processed in the previous pass
+                }
+
+                // `in("explicit register") var`
+                InlineAsmOperandRef::In { reg, value } => {
+                    if let ConstraintOrRegister::Register(reg_name) = reg_to_gcc(reg) {
+                        let ty = value.layout.gcc_type(self.cx, false);
+                        let reg_var = self.current_func().new_local(None, ty, "input_register");
+                        reg_var.set_register_name(reg_name);
+                        self.llbb().add_assignment(None, reg_var, value.immediate());
+
+                        inputs.push(AsmInOperand { 
+                            constraint: "r".into(), 
+                            rust_idx, 
+                            val: reg_var.to_rvalue()
+                        });
+                    }
+
+                    // processed in the previous pass
+                }
+
+                // `inout("explicit register") in_var => out_var`
+                InlineAsmOperandRef::InOut { reg, late, in_value, out_place } => {
+                    if let ConstraintOrRegister::Register(reg_name) = reg_to_gcc(reg) {
+                        let out_place = if let Some(place) = out_place {
+                            place
+                        } 
+                        else {
+                            // processed in the previous pass
+                            continue
+                        };
+
+                        // See explanation in the first pass.
+                        let ty = in_value.layout.gcc_type(self.cx, false);
+                        let tmp_var = self.current_func().new_local(None, ty, "output_register");
+                        tmp_var.set_register_name(reg_name);
+
+                        outputs.push(AsmOutOperand {
+                            constraint: "r".into(), 
+                            rust_idx,
+                            late,
+                            readwrite: false,
+                            tmp_var,
+                            out_place: Some(out_place)
+                        });
+
+                        let constraint = Cow::Owned((outputs.len() - 1).to_string());
+                        inputs.push(AsmInOperand { 
+                            constraint, 
+                            rust_idx,
+                            val: in_value.immediate()
+                        });
+                    }
+
+                    // processed in the previous pass
+                }
+
+                InlineAsmOperandRef::Const { .. } 
+                | InlineAsmOperandRef::SymFn { .. } 
+                | InlineAsmOperandRef::SymStatic { .. } => {
+                    // processed in the previous pass
+                }
+            }
+        }
+
+        // 3. Build the template string
+
+        let mut template_str = String::with_capacity(estimate_template_length(template, constants_len, att_dialect));
+        if !intel_dialect {
+            template_str.push_str(ATT_SYNTAX_INS);
+        }
+
+        for piece in template {
+            match *piece {
+                InlineAsmTemplatePiece::String(ref string) => {
+                    // TODO(@Commeownist): switch to `Iterator::intersperse` once it's stable
+                    let mut iter = string.split('%');
+                    if let Some(s) = iter.next() {
+                        template_str.push_str(s);
+                    }
+
+                    for s in iter {
+                        template_str.push_str("%%");
+                        template_str.push_str(s);
+                    }
+                }
+                InlineAsmTemplatePiece::Placeholder { operand_idx, modifier, span: _ } => {
+                    let mut push_to_template = |modifier, gcc_idx| {
+                        use std::fmt::Write;
+
+                        template_str.push('%');
+                        if let Some(modifier) = modifier {
+                            template_str.push(modifier);
+                        }
+                        write!(template_str, "{}", gcc_idx).expect("pushing to string failed");
+                    };
+
+                    match rust_operands[operand_idx] {
+                        InlineAsmOperandRef::Out { reg, ..  } => {
+                            let modifier = modifier_to_gcc(asm_arch, reg.reg_class(), modifier);
+                            let gcc_index = outputs.iter()
+                                .position(|op| operand_idx == op.rust_idx)
+                                .expect("wrong rust index");
+                            push_to_template(modifier, gcc_index);
+                        }
+
+                        InlineAsmOperandRef::In { reg, .. } => {
+                            let modifier = modifier_to_gcc(asm_arch, reg.reg_class(), modifier);
+                            let in_gcc_index = inputs.iter()
+                                .position(|op| operand_idx == op.rust_idx)
+                                .expect("wrong rust index");
+                            let gcc_index = in_gcc_index + outputs.len();
+                            push_to_template(modifier, gcc_index);
+                        }
+
+                        InlineAsmOperandRef::InOut { reg, .. } => {
+                            let modifier = modifier_to_gcc(asm_arch, reg.reg_class(), modifier);
+
+                            // The input register is tied to the output, so we can just use the index of the output register
+                            let gcc_index = outputs.iter()
+                                .position(|op| operand_idx == op.rust_idx)
+                                .expect("wrong rust index");
+                            push_to_template(modifier, gcc_index);
+                        }
+
+                        InlineAsmOperandRef::SymFn { instance } => {
+                            let name = self.tcx.symbol_name(instance).name;
+                            template_str.push_str(name);
+                        }
+
+                        InlineAsmOperandRef::SymStatic { def_id } => {
+                            // TODO(@Commeownist): This may not be sufficient for all kinds of statics.
+                            // Some statics may need the `@plt` suffix, like thread-local vars.
+                            let instance = Instance::mono(self.tcx, def_id);
+                            let name = self.tcx.symbol_name(instance).name;
+                            template_str.push_str(name);
+                        }
+
+                        InlineAsmOperandRef::Const { ref string } => {
+                            // Const operands get injected directly into the template
+                            if att_dialect {
+                                template_str.push('$');
+                            }
+                            template_str.push_str(string);
+                        }
+                    }
+                }
+            }
+        }
+
+        if !intel_dialect {
+            template_str.push_str(INTEL_SYNTAX_INS);
+        }
+        
+        // 4. Generate Extended Asm block
+
+        let block = self.llbb();
+        let extended_asm = block.add_extended_asm(None, &template_str);
+
+        for op in &outputs {
+            extended_asm.add_output_operand(None, &op.to_constraint(), op.tmp_var);
+        }
+
+        for op in &inputs {
+            extended_asm.add_input_operand(None, &op.constraint, op.val);
+        }
+
+        for clobber in clobbers.iter() {
+            extended_asm.add_clobber(clobber);
+        }
+
+        if !options.contains(InlineAsmOptions::PRESERVES_FLAGS) {
+            // TODO(@Commeownist): I'm not 100% sure this one clobber is sufficient 
+            // on all architectures. For instance, what about FP stack?
+            extended_asm.add_clobber("cc");
+        }
+        if !options.contains(InlineAsmOptions::NOMEM) {
+            extended_asm.add_clobber("memory");
+        }
+        if !options.contains(InlineAsmOptions::PURE) {
+            extended_asm.set_volatile_flag(true);
+        }
+        if !options.contains(InlineAsmOptions::NOSTACK) {
+            // TODO(@Commeownist): figure out how to align stack
+        }
+        if options.contains(InlineAsmOptions::NORETURN) {
+            let builtin_unreachable = self.context.get_builtin_function("__builtin_unreachable");
+            let builtin_unreachable: RValue<'gcc> = unsafe { std::mem::transmute(builtin_unreachable) };
+            self.call(self.type_void(), builtin_unreachable, &[], None);
+        }
+
+        // Write results to outputs. 
+        //
+        // We need to do this because:
+        //  1. Turning `PlaceRef` into `RValue` is error-prone and has nasty edge cases 
+        //     (especially with current `rustc_backend_ssa` API).
+        //  2. Not every output operand has an `out_place`, and it's required by `add_output_operand`.
+        //
+        // Instead, we generate a temporary output variable for each output operand, and then this loop,
+        // generates `out_place = tmp_var;` assignments if out_place exists.
+        for op in &outputs {
+            if let Some(place) = op.out_place {
+                OperandValue::Immediate(op.tmp_var.to_rvalue()).store(self, place);                
+            }
+        }
+
+    }
+}
+
+fn estimate_template_length(template: &[InlineAsmTemplatePiece], constants_len: usize, att_dialect: bool) -> usize {
+    let len: usize = template.iter().map(|piece| {
+        match *piece {
+            InlineAsmTemplatePiece::String(ref string) => {
+                string.len()
+            }
+            InlineAsmTemplatePiece::Placeholder { .. } => {
+                // '%' + 1 char modifier + 1 char index
+                3
+            }
+        }
+    })
+    .sum();
+
+    // increase it by 5% to account for possible '%' signs that'll be duplicated
+    // I pulled the number out of blue, but should be fair enough
+    // as the upper bound
+    let mut res = (len as f32 * 1.05) as usize + constants_len;
+
+    if att_dialect {
+        res += INTEL_SYNTAX_INS.len() + ATT_SYNTAX_INS.len();
+    }
+    res
+}
+
+/// Converts a register class to a GCC constraint code.
+fn reg_to_gcc(reg: InlineAsmRegOrRegClass) -> ConstraintOrRegister {
+    let constraint = match reg {
+        // For vector registers LLVM wants the register name to match the type size.
+        InlineAsmRegOrRegClass::Reg(reg) => {
+            match reg {
+                InlineAsmReg::X86(_) => {
+                    // TODO(antoyo): add support for vector register.
+                    //
+                    // // For explicit registers, we have to create a register variable: https://stackoverflow.com/a/31774784/389119
+                    return ConstraintOrRegister::Register(match reg.name() {
+                        // Some of registers' names does not map 1-1 from rust to gcc
+                        "st(0)" => "st",
+
+                        name => name,
+                    });
+                }
+
+                _ => unimplemented!(),
+            }
+        },
+        InlineAsmRegOrRegClass::RegClass(reg) => match reg {
+            InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::preg) => unimplemented!(),
+            InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::reg) => unimplemented!(),
+            InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::vreg) => unimplemented!(),
+            InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::vreg_low16) => unimplemented!(),
+            InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg) => unimplemented!(),
+            InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg_thumb) => unimplemented!(),
+            InlineAsmRegClass::Arm(ArmInlineAsmRegClass::sreg)
+            | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::dreg_low16)
+            | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::qreg_low8) => unimplemented!(),
+            InlineAsmRegClass::Arm(ArmInlineAsmRegClass::sreg_low16)
+            | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::dreg_low8)
+            | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::qreg_low4) => unimplemented!(),
+            InlineAsmRegClass::Arm(ArmInlineAsmRegClass::dreg)
+            | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::qreg) => unimplemented!(),
+            InlineAsmRegClass::Bpf(_) => unimplemented!(),
+            InlineAsmRegClass::Hexagon(HexagonInlineAsmRegClass::reg) => unimplemented!(),
+            InlineAsmRegClass::Mips(MipsInlineAsmRegClass::reg) => unimplemented!(),
+            InlineAsmRegClass::Mips(MipsInlineAsmRegClass::freg) => unimplemented!(),
+            InlineAsmRegClass::Nvptx(NvptxInlineAsmRegClass::reg16) => unimplemented!(),
+            InlineAsmRegClass::Nvptx(NvptxInlineAsmRegClass::reg32) => unimplemented!(),
+            InlineAsmRegClass::Nvptx(NvptxInlineAsmRegClass::reg64) => unimplemented!(),
+            InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::reg) => unimplemented!(),
+            InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::reg_nonzero) => unimplemented!(),
+            InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::freg) => unimplemented!(),
+            InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::cr)
+            | InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::xer) => {
+                unreachable!("clobber-only")
+            },
+            InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::reg) => unimplemented!(),
+            InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::freg) => unimplemented!(),
+            InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::vreg) => unimplemented!(),
+            InlineAsmRegClass::X86(X86InlineAsmRegClass::reg) => "r",
+            InlineAsmRegClass::X86(X86InlineAsmRegClass::reg_abcd) => "Q",
+            InlineAsmRegClass::X86(X86InlineAsmRegClass::reg_byte) => "q",
+            InlineAsmRegClass::X86(X86InlineAsmRegClass::xmm_reg)
+            | InlineAsmRegClass::X86(X86InlineAsmRegClass::ymm_reg) => "x",
+            InlineAsmRegClass::X86(X86InlineAsmRegClass::zmm_reg) => "v",
+            InlineAsmRegClass::X86(X86InlineAsmRegClass::kreg) => unimplemented!(),
+            InlineAsmRegClass::Wasm(WasmInlineAsmRegClass::local) => unimplemented!(),
+            InlineAsmRegClass::X86(
+                X86InlineAsmRegClass::x87_reg | X86InlineAsmRegClass::mmx_reg,
+            ) => unreachable!("clobber-only"),
+            InlineAsmRegClass::SpirV(SpirVInlineAsmRegClass::reg) => {
+                bug!("GCC backend does not support SPIR-V")
+            }
+            InlineAsmRegClass::S390x(S390xInlineAsmRegClass::reg) => unimplemented!(),
+            InlineAsmRegClass::S390x(S390xInlineAsmRegClass::freg) => unimplemented!(),
+            InlineAsmRegClass::Err => unreachable!(),
+        }
+    };
+
+    ConstraintOrRegister::Constraint(constraint)
+}
+
+/// Type to use for outputs that are discarded. It doesn't really matter what
+/// the type is, as long as it is valid for the constraint code.
+fn dummy_output_type<'gcc, 'tcx>(cx: &CodegenCx<'gcc, 'tcx>, reg: InlineAsmRegClass) -> Type<'gcc> {
+    match reg {
+        InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::reg) => cx.type_i32(),
+        InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::preg) => unimplemented!(),
+        InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::vreg)
+        | InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::vreg_low16) => {
+            unimplemented!()
+        }
+        InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg)
+        | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg_thumb) => cx.type_i32(),
+        InlineAsmRegClass::Arm(ArmInlineAsmRegClass::sreg)
+        | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::sreg_low16) => cx.type_f32(),
+        InlineAsmRegClass::Arm(ArmInlineAsmRegClass::dreg)
+        | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::dreg_low16)
+        | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::dreg_low8) => cx.type_f64(),
+        InlineAsmRegClass::Arm(ArmInlineAsmRegClass::qreg)
+        | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::qreg_low8)
+        | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::qreg_low4) => {
+            unimplemented!()
+        }
+        InlineAsmRegClass::Bpf(_) => unimplemented!(),
+        InlineAsmRegClass::Hexagon(HexagonInlineAsmRegClass::reg) => cx.type_i32(),
+        InlineAsmRegClass::Mips(MipsInlineAsmRegClass::reg) => cx.type_i32(),
+        InlineAsmRegClass::Mips(MipsInlineAsmRegClass::freg) => cx.type_f32(),
+        InlineAsmRegClass::Nvptx(NvptxInlineAsmRegClass::reg16) => cx.type_i16(),
+        InlineAsmRegClass::Nvptx(NvptxInlineAsmRegClass::reg32) => cx.type_i32(),
+        InlineAsmRegClass::Nvptx(NvptxInlineAsmRegClass::reg64) => cx.type_i64(),
+        InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::reg) => cx.type_i32(),
+        InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::reg_nonzero) => cx.type_i32(),
+        InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::freg) => cx.type_f64(),
+        InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::cr)
+        | InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::xer) => {
+            unreachable!("clobber-only")
+        },
+        InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::reg) => cx.type_i32(),
+        InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::freg) => cx.type_f32(),
+        InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::vreg) => cx.type_f32(),
+        InlineAsmRegClass::X86(X86InlineAsmRegClass::reg)
+        | InlineAsmRegClass::X86(X86InlineAsmRegClass::reg_abcd) => cx.type_i32(),
+        InlineAsmRegClass::X86(X86InlineAsmRegClass::reg_byte) => cx.type_i8(),
+        InlineAsmRegClass::X86(X86InlineAsmRegClass::mmx_reg) => unimplemented!(),
+        InlineAsmRegClass::X86(X86InlineAsmRegClass::xmm_reg)
+        | InlineAsmRegClass::X86(X86InlineAsmRegClass::ymm_reg)
+        | InlineAsmRegClass::X86(X86InlineAsmRegClass::zmm_reg) => cx.type_f32(),
+        InlineAsmRegClass::X86(X86InlineAsmRegClass::x87_reg) => unimplemented!(),
+        InlineAsmRegClass::X86(X86InlineAsmRegClass::kreg) => cx.type_i16(),
+        InlineAsmRegClass::Wasm(WasmInlineAsmRegClass::local) => cx.type_i32(),
+        InlineAsmRegClass::SpirV(SpirVInlineAsmRegClass::reg) => {
+            bug!("LLVM backend does not support SPIR-V")
+        },
+        InlineAsmRegClass::S390x(S390xInlineAsmRegClass::reg) => cx.type_i32(),
+        InlineAsmRegClass::S390x(S390xInlineAsmRegClass::freg) => cx.type_f64(),
+        InlineAsmRegClass::Err => unreachable!(),
+    }
+}
+
+impl<'gcc, 'tcx> AsmMethods for CodegenCx<'gcc, 'tcx> {
+    fn codegen_global_asm(&self, template: &[InlineAsmTemplatePiece], operands: &[GlobalAsmOperandRef], options: InlineAsmOptions, _line_spans: &[Span]) {
+        let asm_arch = self.tcx.sess.asm_arch.unwrap();
+
+        // Default to Intel syntax on x86
+        let intel_syntax = matches!(asm_arch, InlineAsmArch::X86 | InlineAsmArch::X86_64)
+            && !options.contains(InlineAsmOptions::ATT_SYNTAX);
+
+        // Build the template string
+        let mut template_str = String::new();
+        for piece in template {
+            match *piece {
+                InlineAsmTemplatePiece::String(ref string) => {
+                    for line in string.lines() {
+                        // NOTE: gcc does not allow inline comment, so remove them.
+                        let line =
+                            if let Some(index) = line.rfind("//") {
+                                &line[..index]
+                            }
+                            else {
+                                line
+                            };
+                        template_str.push_str(line);
+                        template_str.push('\n');
+                    }
+                },
+                InlineAsmTemplatePiece::Placeholder { operand_idx, modifier: _, span: _ } => {
+                    match operands[operand_idx] {
+                        GlobalAsmOperandRef::Const { ref string } => {
+                            // Const operands get injected directly into the
+                            // template. Note that we don't need to escape %
+                            // here unlike normal inline assembly.
+                            template_str.push_str(string);
+                        }
+                    }
+                }
+            }
+        }
+
+        let template_str =
+            if intel_syntax {
+                format!("{}\n\t.intel_syntax noprefix", template_str)
+            }
+            else {
+                format!(".att_syntax\n\t{}\n\t.intel_syntax noprefix", template_str)
+            };
+        // NOTE: seems like gcc will put the asm in the wrong section, so set it to .text manually.
+        let template_str = format!(".pushsection .text\n{}\n.popsection", template_str);
+        self.context.add_top_level_asm(None, &template_str);
+    }
+}
+
+fn modifier_to_gcc(arch: InlineAsmArch, reg: InlineAsmRegClass, modifier: Option<char>) -> Option<char> {
+    match reg {
+        InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::reg) => modifier,
+        InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::preg) => modifier,
+        InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::vreg)
+        | InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::vreg_low16) => {
+            unimplemented!()
+        }
+        InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg)
+        | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg_thumb) => unimplemented!(),
+        InlineAsmRegClass::Arm(ArmInlineAsmRegClass::sreg)
+        | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::sreg_low16) => unimplemented!(),
+        InlineAsmRegClass::Arm(ArmInlineAsmRegClass::dreg)
+        | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::dreg_low16)
+        | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::dreg_low8) => unimplemented!(),
+        InlineAsmRegClass::Arm(ArmInlineAsmRegClass::qreg)
+        | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::qreg_low8)
+        | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::qreg_low4) => {
+            unimplemented!()
+        }
+        InlineAsmRegClass::Bpf(_) => unimplemented!(),
+        InlineAsmRegClass::Hexagon(_) => unimplemented!(),
+        InlineAsmRegClass::Mips(_) => unimplemented!(),
+        InlineAsmRegClass::Nvptx(_) => unimplemented!(),
+        InlineAsmRegClass::PowerPC(_) => unimplemented!(),
+        InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::reg)
+        | InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::freg) => unimplemented!(),
+        InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::vreg) => unimplemented!(),
+        InlineAsmRegClass::X86(X86InlineAsmRegClass::reg)
+        | InlineAsmRegClass::X86(X86InlineAsmRegClass::reg_abcd) => match modifier {
+            None => if arch == InlineAsmArch::X86_64 { Some('q') } else { Some('k') },
+            Some('l') => Some('b'),
+            Some('h') => Some('h'),
+            Some('x') => Some('w'),
+            Some('e') => Some('k'),
+            Some('r') => Some('q'),
+            _ => unreachable!(),
+        },
+        InlineAsmRegClass::X86(X86InlineAsmRegClass::reg_byte) => None,
+        InlineAsmRegClass::X86(reg @ X86InlineAsmRegClass::xmm_reg)
+        | InlineAsmRegClass::X86(reg @ X86InlineAsmRegClass::ymm_reg)
+        | InlineAsmRegClass::X86(reg @ X86InlineAsmRegClass::zmm_reg) => match (reg, modifier) {
+            (X86InlineAsmRegClass::xmm_reg, None) => Some('x'),
+            (X86InlineAsmRegClass::ymm_reg, None) => Some('t'),
+            (X86InlineAsmRegClass::zmm_reg, None) => Some('g'),
+            (_, Some('x')) => Some('x'),
+            (_, Some('y')) => Some('t'),
+            (_, Some('z')) => Some('g'),
+            _ => unreachable!(),
+        },
+        InlineAsmRegClass::X86(X86InlineAsmRegClass::kreg) => None,
+        InlineAsmRegClass::X86(X86InlineAsmRegClass::x87_reg | X86InlineAsmRegClass::mmx_reg) => {
+            unreachable!("clobber-only")
+        }
+        InlineAsmRegClass::Wasm(WasmInlineAsmRegClass::local) => unimplemented!(),
+        InlineAsmRegClass::SpirV(SpirVInlineAsmRegClass::reg) => {
+            bug!("LLVM backend does not support SPIR-V")
+        },
+        InlineAsmRegClass::S390x(S390xInlineAsmRegClass::reg) => unimplemented!(),
+        InlineAsmRegClass::S390x(S390xInlineAsmRegClass::freg) => unimplemented!(),
+        InlineAsmRegClass::Err => unreachable!(),
+    }
+}
diff --git a/compiler/rustc_codegen_gcc/src/back/mod.rs b/compiler/rustc_codegen_gcc/src/back/mod.rs
new file mode 100644
index 00000000000..d692799d764
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/back/mod.rs
@@ -0,0 +1 @@
+pub mod write;
diff --git a/compiler/rustc_codegen_gcc/src/back/write.rs b/compiler/rustc_codegen_gcc/src/back/write.rs
new file mode 100644
index 00000000000..c3e3847823d
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/back/write.rs
@@ -0,0 +1,78 @@
+use std::fs;
+
+use gccjit::OutputKind;
+use rustc_codegen_ssa::{CompiledModule, ModuleCodegen};
+use rustc_codegen_ssa::back::write::{CodegenContext, EmitObj, ModuleConfig};
+use rustc_errors::Handler;
+use rustc_session::config::OutputType;
+use rustc_span::fatal_error::FatalError;
+use rustc_target::spec::SplitDebuginfo;
+
+use crate::{GccCodegenBackend, GccContext};
+
+pub(crate) unsafe fn codegen(cgcx: &CodegenContext<GccCodegenBackend>, _diag_handler: &Handler, module: ModuleCodegen<GccContext>, config: &ModuleConfig) -> Result<CompiledModule, FatalError> {
+    let _timer = cgcx.prof.generic_activity_with_arg("LLVM_module_codegen", &module.name[..]);
+    {
+        let context = &module.module_llvm.context;
+
+        let module_name = module.name.clone();
+        let module_name = Some(&module_name[..]);
+
+        let _bc_out = cgcx.output_filenames.temp_path(OutputType::Bitcode, module_name);
+        let obj_out = cgcx.output_filenames.temp_path(OutputType::Object, module_name);
+
+        if config.bitcode_needed() {
+            // TODO(antoyo)
+        }
+
+        if config.emit_ir {
+            unimplemented!();
+        }
+
+        if config.emit_asm {
+            let _timer = cgcx
+                .prof
+                .generic_activity_with_arg("LLVM_module_codegen_emit_asm", &module.name[..]);
+            let path = cgcx.output_filenames.temp_path(OutputType::Assembly, module_name);
+            context.compile_to_file(OutputKind::Assembler, path.to_str().expect("path to str"));
+        }
+
+        match config.emit_obj {
+            EmitObj::ObjectCode(_) => {
+                let _timer = cgcx
+                    .prof
+                    .generic_activity_with_arg("LLVM_module_codegen_emit_obj", &module.name[..]);
+                match &*module.name {
+                    "std_example.7rcbfp3g-cgu.15" => {
+                        println!("Dumping reproducer {}", module.name);
+                        let _ = fs::create_dir("/tmp/reproducers");
+                        // FIXME(antoyo): segfault in dump_reproducer_to_file() might be caused by
+                        // transmuting an rvalue to an lvalue.
+                        // Segfault is actually in gcc::jit::reproducer::get_identifier_as_lvalue
+                        context.dump_reproducer_to_file(&format!("/tmp/reproducers/{}.c", module.name));
+                        println!("Dumped reproducer {}", module.name);
+                    },
+                    _ => (),
+                }
+                context.compile_to_file(OutputKind::ObjectFile, obj_out.to_str().expect("path to str"));
+            }
+
+            EmitObj::Bitcode => {
+                // TODO(antoyo)
+            }
+
+            EmitObj::None => {}
+        }
+    }
+
+    Ok(module.into_compiled_module(
+        config.emit_obj != EmitObj::None,
+        cgcx.target_can_use_split_dwarf && cgcx.split_debuginfo == SplitDebuginfo::Unpacked,
+        config.emit_bc,
+        &cgcx.output_filenames,
+    ))
+}
+
+pub(crate) fn link(_cgcx: &CodegenContext<GccCodegenBackend>, _diag_handler: &Handler, mut _modules: Vec<ModuleCodegen<GccContext>>) -> Result<ModuleCodegen<GccContext>, FatalError> {
+    unimplemented!();
+}
diff --git a/compiler/rustc_codegen_gcc/src/base.rs b/compiler/rustc_codegen_gcc/src/base.rs
new file mode 100644
index 00000000000..9f96096574f
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/base.rs
@@ -0,0 +1,165 @@
+use std::env;
+use std::time::Instant;
+
+use gccjit::{
+    Context,
+    FunctionType,
+    GlobalKind,
+};
+use rustc_middle::dep_graph;
+use rustc_middle::middle::exported_symbols;
+use rustc_middle::ty::TyCtxt;
+use rustc_middle::mir::mono::Linkage;
+use rustc_codegen_ssa::{ModuleCodegen, ModuleKind};
+use rustc_codegen_ssa::base::maybe_create_entry_wrapper;
+use rustc_codegen_ssa::mono_item::MonoItemExt;
+use rustc_codegen_ssa::traits::DebugInfoMethods;
+use rustc_metadata::EncodedMetadata;
+use rustc_session::config::DebugInfo;
+use rustc_span::Symbol;
+
+use crate::GccContext;
+use crate::builder::Builder;
+use crate::context::CodegenCx;
+
+pub fn global_linkage_to_gcc(linkage: Linkage) -> GlobalKind {
+    match linkage {
+        Linkage::External => GlobalKind::Imported,
+        Linkage::AvailableExternally => GlobalKind::Imported,
+        Linkage::LinkOnceAny => unimplemented!(),
+        Linkage::LinkOnceODR => unimplemented!(),
+        Linkage::WeakAny => unimplemented!(),
+        Linkage::WeakODR => unimplemented!(),
+        Linkage::Appending => unimplemented!(),
+        Linkage::Internal => GlobalKind::Internal,
+        Linkage::Private => GlobalKind::Internal,
+        Linkage::ExternalWeak => GlobalKind::Imported, // TODO(antoyo): should be weak linkage.
+        Linkage::Common => unimplemented!(),
+    }
+}
+
+pub fn linkage_to_gcc(linkage: Linkage) -> FunctionType {
+    match linkage {
+        Linkage::External => FunctionType::Exported,
+        Linkage::AvailableExternally => FunctionType::Extern,
+        Linkage::LinkOnceAny => unimplemented!(),
+        Linkage::LinkOnceODR => unimplemented!(),
+        Linkage::WeakAny => FunctionType::Exported, // FIXME(antoyo): should be similar to linkonce.
+        Linkage::WeakODR => unimplemented!(),
+        Linkage::Appending => unimplemented!(),
+        Linkage::Internal => FunctionType::Internal,
+        Linkage::Private => FunctionType::Internal,
+        Linkage::ExternalWeak => unimplemented!(),
+        Linkage::Common => unimplemented!(),
+    }
+}
+
+pub fn compile_codegen_unit<'tcx>(tcx: TyCtxt<'tcx>, cgu_name: Symbol) -> (ModuleCodegen<GccContext>, u64) {
+    let prof_timer = tcx.prof.generic_activity("codegen_module");
+    let start_time = Instant::now();
+
+    let dep_node = tcx.codegen_unit(cgu_name).codegen_dep_node(tcx);
+    let (module, _) = tcx.dep_graph.with_task(dep_node, tcx, cgu_name, module_codegen, dep_graph::hash_result);
+    let time_to_codegen = start_time.elapsed();
+    drop(prof_timer);
+
+    // We assume that the cost to run GCC on a CGU is proportional to
+    // the time we needed for codegenning it.
+    let cost = time_to_codegen.as_secs() * 1_000_000_000 + time_to_codegen.subsec_nanos() as u64;
+
+    fn module_codegen(tcx: TyCtxt<'_>, cgu_name: Symbol) -> ModuleCodegen<GccContext> {
+        let cgu = tcx.codegen_unit(cgu_name);
+        // Instantiate monomorphizations without filling out definitions yet...
+        //let llvm_module = ModuleLlvm::new(tcx, &cgu_name.as_str());
+        let context = Context::default();
+        // TODO(antoyo): only set on x86 platforms.
+        context.add_command_line_option("-masm=intel");
+        for arg in &tcx.sess.opts.cg.llvm_args {
+            context.add_command_line_option(arg);
+        }
+        context.add_command_line_option("-fno-semantic-interposition");
+        if env::var("CG_GCCJIT_DUMP_CODE").as_deref() == Ok("1") {
+            context.set_dump_code_on_compile(true);
+        }
+        if env::var("CG_GCCJIT_DUMP_GIMPLE").as_deref() == Ok("1") {
+            context.set_dump_initial_gimple(true);
+        }
+        context.set_debug_info(true);
+        if env::var("CG_GCCJIT_DUMP_EVERYTHING").as_deref() == Ok("1") {
+            context.set_dump_everything(true);
+        }
+        if env::var("CG_GCCJIT_KEEP_INTERMEDIATES").as_deref() == Ok("1") {
+            context.set_keep_intermediates(true);
+        }
+
+        {
+            let cx = CodegenCx::new(&context, cgu, tcx);
+
+            let mono_items = cgu.items_in_deterministic_order(tcx);
+            for &(mono_item, (linkage, visibility)) in &mono_items {
+                mono_item.predefine::<Builder<'_, '_, '_>>(&cx, linkage, visibility);
+            }
+
+            // ... and now that we have everything pre-defined, fill out those definitions.
+            for &(mono_item, _) in &mono_items {
+                mono_item.define::<Builder<'_, '_, '_>>(&cx);
+            }
+
+            // If this codegen unit contains the main function, also create the
+            // wrapper here
+            maybe_create_entry_wrapper::<Builder<'_, '_, '_>>(&cx);
+
+            // Finalize debuginfo
+            if cx.sess().opts.debuginfo != DebugInfo::None {
+                cx.debuginfo_finalize();
+            }
+        }
+
+        ModuleCodegen {
+            name: cgu_name.to_string(),
+            module_llvm: GccContext {
+                context
+            },
+            kind: ModuleKind::Regular,
+        }
+    }
+
+    (module, cost)
+}
+
+pub fn write_compressed_metadata<'tcx>(tcx: TyCtxt<'tcx>, metadata: &EncodedMetadata, gcc_module: &mut GccContext) {
+    use snap::write::FrameEncoder;
+    use std::io::Write;
+
+    // Historical note:
+    //
+    // When using link.exe it was seen that the section name `.note.rustc`
+    // was getting shortened to `.note.ru`, and according to the PE and COFF
+    // specification:
+    //
+    // > Executable images do not use a string table and do not support
+    // > section names longer than 8 characters
+    //
+    // https://docs.microsoft.com/en-us/windows/win32/debug/pe-format
+    //
+    // As a result, we choose a slightly shorter name! As to why
+    // `.note.rustc` works on MinGW, see
+    // https://github.com/llvm/llvm-project/blob/llvmorg-12.0.0/lld/COFF/Writer.cpp#L1190-L1197
+    let section_name = if tcx.sess.target.is_like_osx { "__DATA,.rustc" } else { ".rustc" };
+
+    let context = &gcc_module.context;
+    let mut compressed = rustc_metadata::METADATA_HEADER.to_vec();
+    FrameEncoder::new(&mut compressed).write_all(&metadata.raw_data()).unwrap();
+
+    let name = exported_symbols::metadata_symbol_name(tcx);
+    let typ = context.new_array_type(None, context.new_type::<u8>(), compressed.len() as i32);
+    let global = context.new_global(None, GlobalKind::Exported, typ, name);
+    global.global_set_initializer(&compressed);
+    global.set_link_section(section_name);
+
+    // Also generate a .section directive to force no
+    // flags, at least for ELF outputs, so that the
+    // metadata doesn't get loaded into memory.
+    let directive = format!(".section {}", section_name);
+    context.add_top_level_asm(None, &directive);
+}
diff --git a/compiler/rustc_codegen_gcc/src/builder.rs b/compiler/rustc_codegen_gcc/src/builder.rs
new file mode 100644
index 00000000000..ac908418ee4
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/builder.rs
@@ -0,0 +1,1540 @@
+use std::borrow::Cow;
+use std::cell::Cell;
+use std::convert::TryFrom;
+use std::ops::Deref;
+
+use gccjit::FunctionType;
+use gccjit::{
+    BinaryOp,
+    Block,
+    ComparisonOp,
+    Function,
+    LValue,
+    RValue,
+    ToRValue,
+    Type,
+    UnaryOp,
+};
+use rustc_codegen_ssa::MemFlags;
+use rustc_codegen_ssa::common::{AtomicOrdering, AtomicRmwBinOp, IntPredicate, RealPredicate, SynchronizationScope};
+use rustc_codegen_ssa::mir::operand::{OperandRef, OperandValue};
+use rustc_codegen_ssa::mir::place::PlaceRef;
+use rustc_codegen_ssa::traits::{
+    BackendTypes,
+    BaseTypeMethods,
+    BuilderMethods,
+    ConstMethods,
+    DerivedTypeMethods,
+    LayoutTypeMethods,
+    HasCodegen,
+    OverflowOp,
+    StaticBuilderMethods,
+};
+use rustc_middle::ty::{ParamEnv, Ty, TyCtxt};
+use rustc_middle::ty::layout::{FnAbiError, FnAbiOfHelpers, FnAbiRequest, HasParamEnv, HasTyCtxt, LayoutError, LayoutOfHelpers, TyAndLayout};
+use rustc_span::Span;
+use rustc_span::def_id::DefId;
+use rustc_target::abi::{
+    self,
+    call::FnAbi,
+    Align,
+    HasDataLayout,
+    Size,
+    TargetDataLayout,
+    WrappingRange,
+};
+use rustc_target::spec::{HasTargetSpec, Target};
+
+use crate::common::{SignType, TypeReflection, type_is_pointer};
+use crate::context::CodegenCx;
+use crate::type_of::LayoutGccExt;
+
+// TODO(antoyo)
+type Funclet = ();
+
+// TODO(antoyo): remove this variable.
+static mut RETURN_VALUE_COUNT: usize = 0;
+
+enum ExtremumOperation {
+    Max,
+    Min,
+}
+
+trait EnumClone {
+    fn clone(&self) -> Self;
+}
+
+impl EnumClone for AtomicOrdering {
+    fn clone(&self) -> Self {
+        match *self {
+            AtomicOrdering::NotAtomic => AtomicOrdering::NotAtomic,
+            AtomicOrdering::Unordered => AtomicOrdering::Unordered,
+            AtomicOrdering::Monotonic => AtomicOrdering::Monotonic,
+            AtomicOrdering::Acquire => AtomicOrdering::Acquire,
+            AtomicOrdering::Release => AtomicOrdering::Release,
+            AtomicOrdering::AcquireRelease => AtomicOrdering::AcquireRelease,
+            AtomicOrdering::SequentiallyConsistent => AtomicOrdering::SequentiallyConsistent,
+        }
+    }
+}
+
+pub struct Builder<'a: 'gcc, 'gcc, 'tcx> {
+    pub cx: &'a CodegenCx<'gcc, 'tcx>,
+    pub block: Option<Block<'gcc>>,
+    stack_var_count: Cell<usize>,
+}
+
+impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
+    fn with_cx(cx: &'a CodegenCx<'gcc, 'tcx>) -> Self {
+        Builder {
+            cx,
+            block: None,
+            stack_var_count: Cell::new(0),
+        }
+    }
+
+    fn atomic_extremum(&mut self, operation: ExtremumOperation, dst: RValue<'gcc>, src: RValue<'gcc>, order: AtomicOrdering) -> RValue<'gcc> {
+        let size = self.cx.int_width(src.get_type()) / 8;
+
+        let func = self.current_func();
+
+        let load_ordering =
+            match order {
+                // TODO(antoyo): does this make sense?
+                AtomicOrdering::AcquireRelease | AtomicOrdering::Release => AtomicOrdering::Acquire,
+                _ => order.clone(),
+            };
+        let previous_value = self.atomic_load(dst.get_type(), dst, load_ordering.clone(), Size::from_bytes(size));
+        let previous_var = func.new_local(None, previous_value.get_type(), "previous_value");
+        let return_value = func.new_local(None, previous_value.get_type(), "return_value");
+        self.llbb().add_assignment(None, previous_var, previous_value);
+        self.llbb().add_assignment(None, return_value, previous_var.to_rvalue());
+
+        let while_block = func.new_block("while");
+        let after_block = func.new_block("after_while");
+        self.llbb().end_with_jump(None, while_block);
+
+        // NOTE: since jumps were added and compare_exchange doesn't expect this, the current blocks in the
+        // state need to be updated.
+        self.block = Some(while_block);
+        *self.cx.current_block.borrow_mut() = Some(while_block);
+
+        let comparison_operator =
+            match operation {
+                ExtremumOperation::Max => ComparisonOp::LessThan,
+                ExtremumOperation::Min => ComparisonOp::GreaterThan,
+            };
+
+        let cond1 = self.context.new_comparison(None, comparison_operator, previous_var.to_rvalue(), self.context.new_cast(None, src, previous_value.get_type()));
+        let compare_exchange = self.compare_exchange(dst, previous_var, src, order, load_ordering, false);
+        let cond2 = self.cx.context.new_unary_op(None, UnaryOp::LogicalNegate, compare_exchange.get_type(), compare_exchange);
+        let cond = self.cx.context.new_binary_op(None, BinaryOp::LogicalAnd, self.cx.bool_type, cond1, cond2);
+
+        while_block.end_with_conditional(None, cond, while_block, after_block);
+
+        // NOTE: since jumps were added in a place rustc does not expect, the current blocks in the
+        // state need to be updated.
+        self.block = Some(after_block);
+        *self.cx.current_block.borrow_mut() = Some(after_block);
+
+        return_value.to_rvalue()
+    }
+
+    fn compare_exchange(&self, dst: RValue<'gcc>, cmp: LValue<'gcc>, src: RValue<'gcc>, order: AtomicOrdering, failure_order: AtomicOrdering, weak: bool) -> RValue<'gcc> {
+        let size = self.cx.int_width(src.get_type());
+        let compare_exchange = self.context.get_builtin_function(&format!("__atomic_compare_exchange_{}", size / 8));
+        let order = self.context.new_rvalue_from_int(self.i32_type, order.to_gcc());
+        let failure_order = self.context.new_rvalue_from_int(self.i32_type, failure_order.to_gcc());
+        let weak = self.context.new_rvalue_from_int(self.bool_type, weak as i32);
+
+        let void_ptr_type = self.context.new_type::<*mut ()>();
+        let volatile_void_ptr_type = void_ptr_type.make_volatile();
+        let dst = self.context.new_cast(None, dst, volatile_void_ptr_type);
+        let expected = self.context.new_cast(None, cmp.get_address(None), void_ptr_type);
+
+        // NOTE: not sure why, but we have the wrong type here.
+        let int_type = compare_exchange.get_param(2).to_rvalue().get_type();
+        let src = self.context.new_cast(None, src, int_type);
+        self.context.new_call(None, compare_exchange, &[dst, expected, src, weak, order, failure_order])
+    }
+
+    pub fn assign(&self, lvalue: LValue<'gcc>, value: RValue<'gcc>) {
+        self.llbb().add_assignment(None, lvalue, value);
+    }
+
+    fn check_call<'b>(&mut self, _typ: &str, func: Function<'gcc>, args: &'b [RValue<'gcc>]) -> Cow<'b, [RValue<'gcc>]> {
+        let mut all_args_match = true;
+        let mut param_types = vec![];
+        let param_count = func.get_param_count();
+        for (index, arg) in args.iter().enumerate().take(param_count) {
+            let param = func.get_param(index as i32);
+            let param = param.to_rvalue().get_type();
+            if param != arg.get_type() {
+                all_args_match = false;
+            }
+            param_types.push(param);
+        }
+
+        if all_args_match {
+            return Cow::Borrowed(args);
+        }
+
+        let casted_args: Vec<_> = param_types
+            .into_iter()
+            .zip(args.iter())
+            .enumerate()
+            .map(|(_i, (expected_ty, &actual_val))| {
+                let actual_ty = actual_val.get_type();
+                if expected_ty != actual_ty {
+                    self.bitcast(actual_val, expected_ty)
+                }
+                else {
+                    actual_val
+                }
+            })
+            .collect();
+
+        Cow::Owned(casted_args)
+    }
+
+    fn check_ptr_call<'b>(&mut self, _typ: &str, func_ptr: RValue<'gcc>, args: &'b [RValue<'gcc>]) -> Cow<'b, [RValue<'gcc>]> {
+        let mut all_args_match = true;
+        let mut param_types = vec![];
+        let gcc_func = func_ptr.get_type().is_function_ptr_type().expect("function ptr");
+        for (index, arg) in args.iter().enumerate().take(gcc_func.get_param_count()) {
+            let param = gcc_func.get_param_type(index);
+            if param != arg.get_type() {
+                all_args_match = false;
+            }
+            param_types.push(param);
+        }
+
+        if all_args_match {
+            return Cow::Borrowed(args);
+        }
+
+        let casted_args: Vec<_> = param_types
+            .into_iter()
+            .zip(args.iter())
+            .enumerate()
+            .map(|(_i, (expected_ty, &actual_val))| {
+                let actual_ty = actual_val.get_type();
+                if expected_ty != actual_ty {
+                    self.bitcast(actual_val, expected_ty)
+                }
+                else {
+                    actual_val
+                }
+            })
+            .collect();
+
+        Cow::Owned(casted_args)
+    }
+
+    fn check_store(&mut self, val: RValue<'gcc>, ptr: RValue<'gcc>) -> RValue<'gcc> {
+        let dest_ptr_ty = self.cx.val_ty(ptr).make_pointer(); // TODO(antoyo): make sure make_pointer() is okay here.
+        let stored_ty = self.cx.val_ty(val);
+        let stored_ptr_ty = self.cx.type_ptr_to(stored_ty);
+
+        if dest_ptr_ty == stored_ptr_ty {
+            ptr
+        }
+        else {
+            self.bitcast(ptr, stored_ptr_ty)
+        }
+    }
+
+    pub fn current_func(&self) -> Function<'gcc> {
+        self.block.expect("block").get_function()
+    }
+
+    fn function_call(&mut self, func: RValue<'gcc>, args: &[RValue<'gcc>], _funclet: Option<&Funclet>) -> RValue<'gcc> {
+        // TODO(antoyo): remove when the API supports a different type for functions.
+        let func: Function<'gcc> = self.cx.rvalue_as_function(func);
+        let args = self.check_call("call", func, args);
+
+        // gccjit requires to use the result of functions, even when it's not used.
+        // That's why we assign the result to a local or call add_eval().
+        let return_type = func.get_return_type();
+        let current_block = self.current_block.borrow().expect("block");
+        let void_type = self.context.new_type::<()>();
+        let current_func = current_block.get_function();
+        if return_type != void_type {
+            unsafe { RETURN_VALUE_COUNT += 1 };
+            let result = current_func.new_local(None, return_type, &format!("returnValue{}", unsafe { RETURN_VALUE_COUNT }));
+            current_block.add_assignment(None, result, self.cx.context.new_call(None, func, &args));
+            result.to_rvalue()
+        }
+        else {
+            current_block.add_eval(None, self.cx.context.new_call(None, func, &args));
+            // Return dummy value when not having return value.
+            self.context.new_rvalue_from_long(self.isize_type, 0)
+        }
+    }
+
+    fn function_ptr_call(&mut self, func_ptr: RValue<'gcc>, args: &[RValue<'gcc>], _funclet: Option<&Funclet>) -> RValue<'gcc> {
+        let args = self.check_ptr_call("call", func_ptr, args);
+
+        // gccjit requires to use the result of functions, even when it's not used.
+        // That's why we assign the result to a local or call add_eval().
+        let gcc_func = func_ptr.get_type().is_function_ptr_type().expect("function ptr");
+        let mut return_type = gcc_func.get_return_type();
+        let current_block = self.current_block.borrow().expect("block");
+        let void_type = self.context.new_type::<()>();
+        let current_func = current_block.get_function();
+
+        // FIXME(antoyo): As a temporary workaround for unsupported LLVM intrinsics.
+        if gcc_func.get_param_count() == 0 && format!("{:?}", func_ptr) == "__builtin_ia32_pmovmskb128" {
+            return_type = self.int_type;
+        }
+
+        if return_type != void_type {
+            unsafe { RETURN_VALUE_COUNT += 1 };
+            let result = current_func.new_local(None, return_type, &format!("returnValue{}", unsafe { RETURN_VALUE_COUNT }));
+            current_block.add_assignment(None, result, self.cx.context.new_call_through_ptr(None, func_ptr, &args));
+            result.to_rvalue()
+        }
+        else {
+            if gcc_func.get_param_count() == 0 {
+                // FIXME(antoyo): As a temporary workaround for unsupported LLVM intrinsics.
+                current_block.add_eval(None, self.cx.context.new_call_through_ptr(None, func_ptr, &[]));
+            }
+            else {
+                current_block.add_eval(None, self.cx.context.new_call_through_ptr(None, func_ptr, &args));
+            }
+            // Return dummy value when not having return value.
+            let result = current_func.new_local(None, self.isize_type, "dummyValueThatShouldNeverBeUsed");
+            current_block.add_assignment(None, result, self.context.new_rvalue_from_long(self.isize_type, 0));
+            result.to_rvalue()
+        }
+    }
+
+    pub fn overflow_call(&mut self, func: Function<'gcc>, args: &[RValue<'gcc>], _funclet: Option<&Funclet>) -> RValue<'gcc> {
+        // gccjit requires to use the result of functions, even when it's not used.
+        // That's why we assign the result to a local.
+        let return_type = self.context.new_type::<bool>();
+        let current_block = self.current_block.borrow().expect("block");
+        let current_func = current_block.get_function();
+        // TODO(antoyo): return the new_call() directly? Since the overflow function has no side-effects.
+        unsafe { RETURN_VALUE_COUNT += 1 };
+        let result = current_func.new_local(None, return_type, &format!("returnValue{}", unsafe { RETURN_VALUE_COUNT }));
+        current_block.add_assignment(None, result, self.cx.context.new_call(None, func, &args));
+        result.to_rvalue()
+    }
+}
+
+impl<'gcc, 'tcx> HasCodegen<'tcx> for Builder<'_, 'gcc, 'tcx> {
+    type CodegenCx = CodegenCx<'gcc, 'tcx>;
+}
+
+impl<'tcx> HasTyCtxt<'tcx> for Builder<'_, '_, 'tcx> {
+    fn tcx(&self) -> TyCtxt<'tcx> {
+        self.cx.tcx()
+    }
+}
+
+impl HasDataLayout for Builder<'_, '_, '_> {
+    fn data_layout(&self) -> &TargetDataLayout {
+        self.cx.data_layout()
+    }
+}
+
+impl<'tcx> LayoutOfHelpers<'tcx> for Builder<'_, '_, 'tcx> {
+    type LayoutOfResult = TyAndLayout<'tcx>;
+
+    #[inline]
+    fn handle_layout_err(&self, err: LayoutError<'tcx>, span: Span, ty: Ty<'tcx>) -> ! {
+        self.cx.handle_layout_err(err, span, ty)
+    }
+}
+
+impl<'tcx> FnAbiOfHelpers<'tcx> for Builder<'_, '_, 'tcx> {
+    type FnAbiOfResult = &'tcx FnAbi<'tcx, Ty<'tcx>>;
+
+    #[inline]
+    fn handle_fn_abi_err(
+        &self,
+        err: FnAbiError<'tcx>,
+        span: Span,
+        fn_abi_request: FnAbiRequest<'tcx>,
+    ) -> ! {
+        self.cx.handle_fn_abi_err(err, span, fn_abi_request)
+    }
+}
+
+impl<'gcc, 'tcx> Deref for Builder<'_, 'gcc, 'tcx> {
+    type Target = CodegenCx<'gcc, 'tcx>;
+
+    fn deref(&self) -> &Self::Target {
+        self.cx
+    }
+}
+
+impl<'gcc, 'tcx> BackendTypes for Builder<'_, 'gcc, 'tcx> {
+    type Value = <CodegenCx<'gcc, 'tcx> as BackendTypes>::Value;
+    type Function = <CodegenCx<'gcc, 'tcx> as BackendTypes>::Function;
+    type BasicBlock = <CodegenCx<'gcc, 'tcx> as BackendTypes>::BasicBlock;
+    type Type = <CodegenCx<'gcc, 'tcx> as BackendTypes>::Type;
+    type Funclet = <CodegenCx<'gcc, 'tcx> as BackendTypes>::Funclet;
+
+    type DIScope = <CodegenCx<'gcc, 'tcx> as BackendTypes>::DIScope;
+    type DILocation = <CodegenCx<'gcc, 'tcx> as BackendTypes>::DILocation;
+    type DIVariable = <CodegenCx<'gcc, 'tcx> as BackendTypes>::DIVariable;
+}
+
+impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
+    fn build(cx: &'a CodegenCx<'gcc, 'tcx>, block: Block<'gcc>) -> Self {
+        let mut bx = Builder::with_cx(cx);
+        *cx.current_block.borrow_mut() = Some(block);
+        bx.block = Some(block);
+        bx
+    }
+
+    fn build_sibling_block(&mut self, name: &str) -> Self {
+        let block = self.append_sibling_block(name);
+        Self::build(self.cx, block)
+    }
+
+    fn llbb(&self) -> Block<'gcc> {
+        self.block.expect("block")
+    }
+
+    fn append_block(cx: &'a CodegenCx<'gcc, 'tcx>, func: RValue<'gcc>, name: &str) -> Block<'gcc> {
+        let func = cx.rvalue_as_function(func);
+        func.new_block(name)
+    }
+
+    fn append_sibling_block(&mut self, name: &str) -> Block<'gcc> {
+        let func = self.current_func();
+        func.new_block(name)
+    }
+
+    fn ret_void(&mut self) {
+        self.llbb().end_with_void_return(None)
+    }
+
+    fn ret(&mut self, value: RValue<'gcc>) {
+        let value =
+            if self.structs_as_pointer.borrow().contains(&value) {
+                // NOTE: hack to workaround a limitation of the rustc API: see comment on
+                // CodegenCx.structs_as_pointer
+                value.dereference(None).to_rvalue()
+            }
+            else {
+                value
+            };
+        self.llbb().end_with_return(None, value);
+    }
+
+    fn br(&mut self, dest: Block<'gcc>) {
+        self.llbb().end_with_jump(None, dest)
+    }
+
+    fn cond_br(&mut self, cond: RValue<'gcc>, then_block: Block<'gcc>, else_block: Block<'gcc>) {
+        self.llbb().end_with_conditional(None, cond, then_block, else_block)
+    }
+
+    fn switch(&mut self, value: RValue<'gcc>, default_block: Block<'gcc>, cases: impl ExactSizeIterator<Item = (u128, Block<'gcc>)>) {
+        let mut gcc_cases = vec![];
+        let typ = self.val_ty(value);
+        for (on_val, dest) in cases {
+            let on_val = self.const_uint_big(typ, on_val);
+            gcc_cases.push(self.context.new_case(on_val, on_val, dest));
+        }
+        self.block.expect("block").end_with_switch(None, value, default_block, &gcc_cases);
+    }
+
+    fn invoke(&mut self, _typ: Type<'gcc>, _func: RValue<'gcc>, _args: &[RValue<'gcc>], then: Block<'gcc>, catch: Block<'gcc>, _funclet: Option<&Funclet>) -> RValue<'gcc> {
+        let condition = self.context.new_rvalue_from_int(self.bool_type, 0);
+        self.llbb().end_with_conditional(None, condition, then, catch);
+        self.context.new_rvalue_from_int(self.int_type, 0)
+
+        // TODO(antoyo)
+    }
+
+    fn unreachable(&mut self) {
+        let func = self.context.get_builtin_function("__builtin_unreachable");
+        let block = self.block.expect("block");
+        block.add_eval(None, self.context.new_call(None, func, &[]));
+        let return_type = block.get_function().get_return_type();
+        let void_type = self.context.new_type::<()>();
+        if return_type == void_type {
+            block.end_with_void_return(None)
+        }
+        else {
+            let return_value = self.current_func()
+                .new_local(None, return_type, "unreachableReturn");
+            block.end_with_return(None, return_value)
+        }
+    }
+
+    fn add(&mut self, a: RValue<'gcc>, mut b: RValue<'gcc>) -> RValue<'gcc> {
+        // FIXME(antoyo): this should not be required.
+        if format!("{:?}", a.get_type()) != format!("{:?}", b.get_type()) {
+            b = self.context.new_cast(None, b, a.get_type());
+        }
+        a + b
+    }
+
+    fn fadd(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        a + b
+    }
+
+    fn sub(&mut self, a: RValue<'gcc>, mut b: RValue<'gcc>) -> RValue<'gcc> {
+        if a.get_type() != b.get_type() {
+            b = self.context.new_cast(None, b, a.get_type());
+        }
+        a - b
+    }
+
+    fn fsub(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        a - b
+    }
+
+    fn mul(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        a * b
+    }
+
+    fn fmul(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        a * b
+    }
+
+    fn udiv(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        // TODO(antoyo): convert the arguments to unsigned?
+        a / b
+    }
+
+    fn exactudiv(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        // TODO(antoyo): convert the arguments to unsigned?
+        // TODO(antoyo): poison if not exact.
+        a / b
+    }
+
+    fn sdiv(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        // TODO(antoyo): convert the arguments to signed?
+        a / b
+    }
+
+    fn exactsdiv(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        // TODO(antoyo): posion if not exact.
+        // FIXME(antoyo): rustc_codegen_ssa::mir::intrinsic uses different types for a and b but they
+        // should be the same.
+        let typ = a.get_type().to_signed(self);
+        let b = self.context.new_cast(None, b, typ);
+        a / b
+    }
+
+    fn fdiv(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        a / b
+    }
+
+    fn urem(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        a % b
+    }
+
+    fn srem(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        a % b
+    }
+
+    fn frem(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        if a.get_type() == self.cx.float_type {
+            let fmodf = self.context.get_builtin_function("fmodf");
+            // FIXME(antoyo): this seems to produce the wrong result.
+            return self.context.new_call(None, fmodf, &[a, b]);
+        }
+        assert_eq!(a.get_type(), self.cx.double_type);
+
+        let fmod = self.context.get_builtin_function("fmod");
+        return self.context.new_call(None, fmod, &[a, b]);
+    }
+
+    fn shl(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        // FIXME(antoyo): remove the casts when libgccjit can shift an unsigned number by an unsigned number.
+        let a_type = a.get_type();
+        let b_type = b.get_type();
+        if a_type.is_unsigned(self) && b_type.is_signed(self) {
+            let a = self.context.new_cast(None, a, b_type);
+            let result = a << b;
+            self.context.new_cast(None, result, a_type)
+        }
+        else if a_type.is_signed(self) && b_type.is_unsigned(self) {
+            let b = self.context.new_cast(None, b, a_type);
+            a << b
+        }
+        else {
+            a << b
+        }
+    }
+
+    fn lshr(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        // FIXME(antoyo): remove the casts when libgccjit can shift an unsigned number by an unsigned number.
+        // TODO(antoyo): cast to unsigned to do a logical shift if that does not work.
+        let a_type = a.get_type();
+        let b_type = b.get_type();
+        if a_type.is_unsigned(self) && b_type.is_signed(self) {
+            let a = self.context.new_cast(None, a, b_type);
+            let result = a >> b;
+            self.context.new_cast(None, result, a_type)
+        }
+        else if a_type.is_signed(self) && b_type.is_unsigned(self) {
+            let b = self.context.new_cast(None, b, a_type);
+            a >> b
+        }
+        else {
+            a >> b
+        }
+    }
+
+    fn ashr(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        // TODO(antoyo): check whether behavior is an arithmetic shift for >> .
+        // FIXME(antoyo): remove the casts when libgccjit can shift an unsigned number by an unsigned number.
+        let a_type = a.get_type();
+        let b_type = b.get_type();
+        if a_type.is_unsigned(self) && b_type.is_signed(self) {
+            let a = self.context.new_cast(None, a, b_type);
+            let result = a >> b;
+            self.context.new_cast(None, result, a_type)
+        }
+        else if a_type.is_signed(self) && b_type.is_unsigned(self) {
+            let b = self.context.new_cast(None, b, a_type);
+            a >> b
+        }
+        else {
+            a >> b
+        }
+    }
+
+    fn and(&mut self, a: RValue<'gcc>, mut b: RValue<'gcc>) -> RValue<'gcc> {
+        // FIXME(antoyo): hack by putting the result in a variable to workaround this bug:
+        // https://gcc.gnu.org/bugzilla//show_bug.cgi?id=95498
+        if a.get_type() != b.get_type() {
+            b = self.context.new_cast(None, b, a.get_type());
+        }
+        let res = self.current_func().new_local(None, b.get_type(), "andResult");
+        self.llbb().add_assignment(None, res, a & b);
+        res.to_rvalue()
+    }
+
+    fn or(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        // FIXME(antoyo): hack by putting the result in a variable to workaround this bug:
+        // https://gcc.gnu.org/bugzilla//show_bug.cgi?id=95498
+        let res = self.current_func().new_local(None, b.get_type(), "orResult");
+        self.llbb().add_assignment(None, res, a | b);
+        res.to_rvalue()
+    }
+
+    fn xor(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        a ^ b
+    }
+
+    fn neg(&mut self, a: RValue<'gcc>) -> RValue<'gcc> {
+        // TODO(antoyo): use new_unary_op()?
+        self.cx.context.new_rvalue_from_long(a.get_type(), 0) - a
+    }
+
+    fn fneg(&mut self, a: RValue<'gcc>) -> RValue<'gcc> {
+        self.cx.context.new_unary_op(None, UnaryOp::Minus, a.get_type(), a)
+    }
+
+    fn not(&mut self, a: RValue<'gcc>) -> RValue<'gcc> {
+        let operation =
+            if a.get_type().is_bool() {
+                UnaryOp::LogicalNegate
+            }
+            else {
+                UnaryOp::BitwiseNegate
+            };
+        self.cx.context.new_unary_op(None, operation, a.get_type(), a)
+    }
+
+    fn unchecked_sadd(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        a + b
+    }
+
+    fn unchecked_uadd(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        a + b
+    }
+
+    fn unchecked_ssub(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        a - b
+    }
+
+    fn unchecked_usub(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        // TODO(antoyo): should generate poison value?
+        a - b
+    }
+
+    fn unchecked_smul(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        a * b
+    }
+
+    fn unchecked_umul(&mut self, a: RValue<'gcc>, b: RValue<'gcc>) -> RValue<'gcc> {
+        a * b
+    }
+
+    fn fadd_fast(&mut self, _lhs: RValue<'gcc>, _rhs: RValue<'gcc>) -> RValue<'gcc> {
+        unimplemented!();
+    }
+
+    fn fsub_fast(&mut self, _lhs: RValue<'gcc>, _rhs: RValue<'gcc>) -> RValue<'gcc> {
+        unimplemented!();
+    }
+
+    fn fmul_fast(&mut self, _lhs: RValue<'gcc>, _rhs: RValue<'gcc>) -> RValue<'gcc> {
+        unimplemented!();
+    }
+
+    fn fdiv_fast(&mut self, _lhs: RValue<'gcc>, _rhs: RValue<'gcc>) -> RValue<'gcc> {
+        unimplemented!();
+    }
+
+    fn frem_fast(&mut self, _lhs: RValue<'gcc>, _rhs: RValue<'gcc>) -> RValue<'gcc> {
+        unimplemented!();
+    }
+
+    fn checked_binop(&mut self, oop: OverflowOp, typ: Ty<'_>, lhs: Self::Value, rhs: Self::Value) -> (Self::Value, Self::Value) {
+        use rustc_middle::ty::{Int, IntTy::*, Uint, UintTy::*};
+
+        let new_kind =
+            match typ.kind() {
+                Int(t @ Isize) => Int(t.normalize(self.tcx.sess.target.pointer_width)),
+                Uint(t @ Usize) => Uint(t.normalize(self.tcx.sess.target.pointer_width)),
+                t @ (Uint(_) | Int(_)) => t.clone(),
+                _ => panic!("tried to get overflow intrinsic for op applied to non-int type"),
+            };
+
+        // TODO(antoyo): remove duplication with intrinsic?
+        let name =
+            match oop {
+                OverflowOp::Add =>
+                    match new_kind {
+                        Int(I8) => "__builtin_add_overflow",
+                        Int(I16) => "__builtin_add_overflow",
+                        Int(I32) => "__builtin_sadd_overflow",
+                        Int(I64) => "__builtin_saddll_overflow",
+                        Int(I128) => "__builtin_add_overflow",
+
+                        Uint(U8) => "__builtin_add_overflow",
+                        Uint(U16) => "__builtin_add_overflow",
+                        Uint(U32) => "__builtin_uadd_overflow",
+                        Uint(U64) => "__builtin_uaddll_overflow",
+                        Uint(U128) => "__builtin_add_overflow",
+
+                        _ => unreachable!(),
+                    },
+                OverflowOp::Sub =>
+                    match new_kind {
+                        Int(I8) => "__builtin_sub_overflow",
+                        Int(I16) => "__builtin_sub_overflow",
+                        Int(I32) => "__builtin_ssub_overflow",
+                        Int(I64) => "__builtin_ssubll_overflow",
+                        Int(I128) => "__builtin_sub_overflow",
+
+                        Uint(U8) => "__builtin_sub_overflow",
+                        Uint(U16) => "__builtin_sub_overflow",
+                        Uint(U32) => "__builtin_usub_overflow",
+                        Uint(U64) => "__builtin_usubll_overflow",
+                        Uint(U128) => "__builtin_sub_overflow",
+
+                        _ => unreachable!(),
+                    },
+                OverflowOp::Mul =>
+                    match new_kind {
+                        Int(I8) => "__builtin_mul_overflow",
+                        Int(I16) => "__builtin_mul_overflow",
+                        Int(I32) => "__builtin_smul_overflow",
+                        Int(I64) => "__builtin_smulll_overflow",
+                        Int(I128) => "__builtin_mul_overflow",
+
+                        Uint(U8) => "__builtin_mul_overflow",
+                        Uint(U16) => "__builtin_mul_overflow",
+                        Uint(U32) => "__builtin_umul_overflow",
+                        Uint(U64) => "__builtin_umulll_overflow",
+                        Uint(U128) => "__builtin_mul_overflow",
+
+                        _ => unreachable!(),
+                    },
+            };
+
+        let intrinsic = self.context.get_builtin_function(&name);
+        let res = self.current_func()
+            // TODO(antoyo): is it correct to use rhs type instead of the parameter typ?
+            .new_local(None, rhs.get_type(), "binopResult")
+            .get_address(None);
+        let overflow = self.overflow_call(intrinsic, &[lhs, rhs, res], None);
+        (res.dereference(None).to_rvalue(), overflow)
+    }
+
+    fn alloca(&mut self, ty: Type<'gcc>, align: Align) -> RValue<'gcc> {
+        // FIXME(antoyo): this check that we don't call get_aligned() a second time on a type.
+        // Ideally, we shouldn't need to do this check.
+        let aligned_type =
+            if ty == self.cx.u128_type || ty == self.cx.i128_type {
+                ty
+            }
+            else {
+                ty.get_aligned(align.bytes())
+            };
+        // TODO(antoyo): It might be better to return a LValue, but fixing the rustc API is non-trivial.
+        self.stack_var_count.set(self.stack_var_count.get() + 1);
+        self.current_func().new_local(None, aligned_type, &format!("stack_var_{}", self.stack_var_count.get())).get_address(None)
+    }
+
+    fn dynamic_alloca(&mut self, _ty: Type<'gcc>, _align: Align) -> RValue<'gcc> {
+        unimplemented!();
+    }
+
+    fn array_alloca(&mut self, _ty: Type<'gcc>, _len: RValue<'gcc>, _align: Align) -> RValue<'gcc> {
+        unimplemented!();
+    }
+
+    fn load(&mut self, _ty: Type<'gcc>, ptr: RValue<'gcc>, _align: Align) -> RValue<'gcc> {
+        // TODO(antoyo): use ty.
+        let block = self.llbb();
+        let function = block.get_function();
+        // NOTE: instead of returning the dereference here, we have to assign it to a variable in
+        // the current basic block. Otherwise, it could be used in another basic block, causing a
+        // dereference after a drop, for instance.
+        // TODO(antoyo): handle align.
+        let deref = ptr.dereference(None).to_rvalue();
+        let value_type = deref.get_type();
+        unsafe { RETURN_VALUE_COUNT += 1 };
+        let loaded_value = function.new_local(None, value_type, &format!("loadedValue{}", unsafe { RETURN_VALUE_COUNT }));
+        block.add_assignment(None, loaded_value, deref);
+        loaded_value.to_rvalue()
+    }
+
+    fn volatile_load(&mut self, _ty: Type<'gcc>, ptr: RValue<'gcc>) -> RValue<'gcc> {
+        // TODO(antoyo): use ty.
+        let ptr = self.context.new_cast(None, ptr, ptr.get_type().make_volatile());
+        ptr.dereference(None).to_rvalue()
+    }
+
+    fn atomic_load(&mut self, _ty: Type<'gcc>, ptr: RValue<'gcc>, order: AtomicOrdering, size: Size) -> RValue<'gcc> {
+        // TODO(antoyo): use ty.
+        // TODO(antoyo): handle alignment.
+        let atomic_load = self.context.get_builtin_function(&format!("__atomic_load_{}", size.bytes()));
+        let ordering = self.context.new_rvalue_from_int(self.i32_type, order.to_gcc());
+
+        let volatile_const_void_ptr_type = self.context.new_type::<*mut ()>().make_const().make_volatile();
+        let ptr = self.context.new_cast(None, ptr, volatile_const_void_ptr_type);
+        self.context.new_call(None, atomic_load, &[ptr, ordering])
+    }
+
+    fn load_operand(&mut self, place: PlaceRef<'tcx, RValue<'gcc>>) -> OperandRef<'tcx, RValue<'gcc>> {
+        assert_eq!(place.llextra.is_some(), place.layout.is_unsized());
+
+        if place.layout.is_zst() {
+            return OperandRef::new_zst(self, place.layout);
+        }
+
+        fn scalar_load_metadata<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>, load: RValue<'gcc>, scalar: &abi::Scalar) {
+            let vr = scalar.valid_range.clone();
+            match scalar.value {
+                abi::Int(..) => {
+                    if !scalar.is_always_valid(bx) {
+                        bx.range_metadata(load, scalar.valid_range);
+                    }
+                }
+                abi::Pointer if vr.start < vr.end && !vr.contains(0) => {
+                    bx.nonnull_metadata(load);
+                }
+                _ => {}
+            }
+        }
+
+        let val =
+            if let Some(llextra) = place.llextra {
+                OperandValue::Ref(place.llval, Some(llextra), place.align)
+            }
+            else if place.layout.is_gcc_immediate() {
+                let load = self.load(place.llval.get_type(), place.llval, place.align);
+                if let abi::Abi::Scalar(ref scalar) = place.layout.abi {
+                    scalar_load_metadata(self, load, scalar);
+                }
+                OperandValue::Immediate(self.to_immediate(load, place.layout))
+            }
+            else if let abi::Abi::ScalarPair(ref a, ref b) = place.layout.abi {
+                let b_offset = a.value.size(self).align_to(b.value.align(self).abi);
+                let pair_type = place.layout.gcc_type(self, false);
+
+                let mut load = |i, scalar: &abi::Scalar, align| {
+                    let llptr = self.struct_gep(pair_type, place.llval, i as u64);
+                    let load = self.load(llptr.get_type(), llptr, align);
+                    scalar_load_metadata(self, load, scalar);
+                    if scalar.is_bool() { self.trunc(load, self.type_i1()) } else { load }
+                };
+
+                OperandValue::Pair(
+                    load(0, a, place.align),
+                    load(1, b, place.align.restrict_for_offset(b_offset)),
+                )
+            }
+            else {
+                OperandValue::Ref(place.llval, None, place.align)
+            };
+
+        OperandRef { val, layout: place.layout }
+    }
+
+    fn write_operand_repeatedly(mut self, cg_elem: OperandRef<'tcx, RValue<'gcc>>, count: u64, dest: PlaceRef<'tcx, RValue<'gcc>>) -> Self {
+        let zero = self.const_usize(0);
+        let count = self.const_usize(count);
+        let start = dest.project_index(&mut self, zero).llval;
+        let end = dest.project_index(&mut self, count).llval;
+
+        let mut header_bx = self.build_sibling_block("repeat_loop_header");
+        let mut body_bx = self.build_sibling_block("repeat_loop_body");
+        let next_bx = self.build_sibling_block("repeat_loop_next");
+
+        let ptr_type = start.get_type();
+        let current = self.llbb().get_function().new_local(None, ptr_type, "loop_var");
+        let current_val = current.to_rvalue();
+        self.assign(current, start);
+
+        self.br(header_bx.llbb());
+
+        let keep_going = header_bx.icmp(IntPredicate::IntNE, current_val, end);
+        header_bx.cond_br(keep_going, body_bx.llbb(), next_bx.llbb());
+
+        let align = dest.align.restrict_for_offset(dest.layout.field(self.cx(), 0).size);
+        cg_elem.val.store(&mut body_bx, PlaceRef::new_sized_aligned(current_val, cg_elem.layout, align));
+
+        let next = body_bx.inbounds_gep(self.backend_type(cg_elem.layout), current.to_rvalue(), &[self.const_usize(1)]);
+        body_bx.llbb().add_assignment(None, current, next);
+        body_bx.br(header_bx.llbb());
+
+        next_bx
+    }
+
+    fn range_metadata(&mut self, _load: RValue<'gcc>, _range: WrappingRange) {
+        // TODO(antoyo)
+    }
+
+    fn nonnull_metadata(&mut self, _load: RValue<'gcc>) {
+        // TODO(antoyo)
+    }
+
+    fn store(&mut self, val: RValue<'gcc>, ptr: RValue<'gcc>, align: Align) -> RValue<'gcc> {
+        self.store_with_flags(val, ptr, align, MemFlags::empty())
+    }
+
+    fn store_with_flags(&mut self, val: RValue<'gcc>, ptr: RValue<'gcc>, _align: Align, _flags: MemFlags) -> RValue<'gcc> {
+        let ptr = self.check_store(val, ptr);
+        self.llbb().add_assignment(None, ptr.dereference(None), val);
+        // TODO(antoyo): handle align and flags.
+        // NOTE: dummy value here since it's never used. FIXME(antoyo): API should not return a value here?
+        self.cx.context.new_rvalue_zero(self.type_i32())
+    }
+
+    fn atomic_store(&mut self, value: RValue<'gcc>, ptr: RValue<'gcc>, order: AtomicOrdering, size: Size) {
+        // TODO(antoyo): handle alignment.
+        let atomic_store = self.context.get_builtin_function(&format!("__atomic_store_{}", size.bytes()));
+        let ordering = self.context.new_rvalue_from_int(self.i32_type, order.to_gcc());
+        let volatile_const_void_ptr_type = self.context.new_type::<*mut ()>().make_const().make_volatile();
+        let ptr = self.context.new_cast(None, ptr, volatile_const_void_ptr_type);
+
+        // FIXME(antoyo): fix libgccjit to allow comparing an integer type with an aligned integer type because
+        // the following cast is required to avoid this error:
+        // gcc_jit_context_new_call: mismatching types for argument 2 of function "__atomic_store_4": assignment to param arg1 (type: int) from loadedValue3577 (type: unsigned int  __attribute__((aligned(4))))
+        let int_type = atomic_store.get_param(1).to_rvalue().get_type();
+        let value = self.context.new_cast(None, value, int_type);
+        self.llbb()
+            .add_eval(None, self.context.new_call(None, atomic_store, &[ptr, value, ordering]));
+    }
+
+    fn gep(&mut self, _typ: Type<'gcc>, ptr: RValue<'gcc>, indices: &[RValue<'gcc>]) -> RValue<'gcc> {
+        let mut result = ptr;
+        for index in indices {
+            result = self.context.new_array_access(None, result, *index).get_address(None).to_rvalue();
+        }
+        result
+    }
+
+    fn inbounds_gep(&mut self, _typ: Type<'gcc>, ptr: RValue<'gcc>, indices: &[RValue<'gcc>]) -> RValue<'gcc> {
+        // FIXME(antoyo): would be safer if doing the same thing (loop) as gep.
+        // TODO(antoyo): specify inbounds somehow.
+        match indices.len() {
+            1 => {
+                self.context.new_array_access(None, ptr, indices[0]).get_address(None)
+            },
+            2 => {
+                let array = ptr.dereference(None); // TODO(antoyo): assert that first index is 0?
+                self.context.new_array_access(None, array, indices[1]).get_address(None)
+            },
+            _ => unimplemented!(),
+        }
+    }
+
+    fn struct_gep(&mut self, value_type: Type<'gcc>, ptr: RValue<'gcc>, idx: u64) -> RValue<'gcc> {
+        // FIXME(antoyo): it would be better if the API only called this on struct, not on arrays.
+        assert_eq!(idx as usize as u64, idx);
+        let value = ptr.dereference(None).to_rvalue();
+
+        if value_type.is_array().is_some() {
+            let index = self.context.new_rvalue_from_long(self.u64_type, i64::try_from(idx).expect("i64::try_from"));
+            let element = self.context.new_array_access(None, value, index);
+            element.get_address(None)
+        }
+        else if let Some(vector_type) = value_type.is_vector() {
+            let array_type = vector_type.get_element_type().make_pointer();
+            let array = self.bitcast(ptr, array_type);
+            let index = self.context.new_rvalue_from_long(self.u64_type, i64::try_from(idx).expect("i64::try_from"));
+            let element = self.context.new_array_access(None, array, index);
+            element.get_address(None)
+        }
+        else if let Some(struct_type) = value_type.is_struct() {
+            ptr.dereference_field(None, struct_type.get_field(idx as i32)).get_address(None)
+        }
+        else {
+            panic!("Unexpected type {:?}", value_type);
+        }
+    }
+
+    /* Casts */
+    fn trunc(&mut self, value: RValue<'gcc>, dest_ty: Type<'gcc>) -> RValue<'gcc> {
+        // TODO(antoyo): check that it indeed truncate the value.
+        self.context.new_cast(None, value, dest_ty)
+    }
+
+    fn sext(&mut self, value: RValue<'gcc>, dest_ty: Type<'gcc>) -> RValue<'gcc> {
+        // TODO(antoyo): check that it indeed sign extend the value.
+        if dest_ty.is_vector().is_some() {
+            // TODO(antoyo): nothing to do as it is only for LLVM?
+            return value;
+        }
+        self.context.new_cast(None, value, dest_ty)
+    }
+
+    fn fptoui(&mut self, value: RValue<'gcc>, dest_ty: Type<'gcc>) -> RValue<'gcc> {
+        self.context.new_cast(None, value, dest_ty)
+    }
+
+    fn fptosi(&mut self, value: RValue<'gcc>, dest_ty: Type<'gcc>) -> RValue<'gcc> {
+        self.context.new_cast(None, value, dest_ty)
+    }
+
+    fn uitofp(&mut self, value: RValue<'gcc>, dest_ty: Type<'gcc>) -> RValue<'gcc> {
+        self.context.new_cast(None, value, dest_ty)
+    }
+
+    fn sitofp(&mut self, value: RValue<'gcc>, dest_ty: Type<'gcc>) -> RValue<'gcc> {
+        self.context.new_cast(None, value, dest_ty)
+    }
+
+    fn fptrunc(&mut self, value: RValue<'gcc>, dest_ty: Type<'gcc>) -> RValue<'gcc> {
+        // TODO(antoyo): make sure it truncates.
+        self.context.new_cast(None, value, dest_ty)
+    }
+
+    fn fpext(&mut self, value: RValue<'gcc>, dest_ty: Type<'gcc>) -> RValue<'gcc> {
+        self.context.new_cast(None, value, dest_ty)
+    }
+
+    fn ptrtoint(&mut self, value: RValue<'gcc>, dest_ty: Type<'gcc>) -> RValue<'gcc> {
+        self.cx.ptrtoint(self.block.expect("block"), value, dest_ty)
+    }
+
+    fn inttoptr(&mut self, value: RValue<'gcc>, dest_ty: Type<'gcc>) -> RValue<'gcc> {
+        self.cx.inttoptr(self.block.expect("block"), value, dest_ty)
+    }
+
+    fn bitcast(&mut self, value: RValue<'gcc>, dest_ty: Type<'gcc>) -> RValue<'gcc> {
+        self.cx.const_bitcast(value, dest_ty)
+    }
+
+    fn intcast(&mut self, value: RValue<'gcc>, dest_typ: Type<'gcc>, _is_signed: bool) -> RValue<'gcc> {
+        // NOTE: is_signed is for value, not dest_typ.
+        self.cx.context.new_cast(None, value, dest_typ)
+    }
+
+    fn pointercast(&mut self, value: RValue<'gcc>, dest_ty: Type<'gcc>) -> RValue<'gcc> {
+        let val_type = value.get_type();
+        match (type_is_pointer(val_type), type_is_pointer(dest_ty)) {
+            (false, true) => {
+                // NOTE: Projecting a field of a pointer type will attemp a cast from a signed char to
+                // a pointer, which is not supported by gccjit.
+                return self.cx.context.new_cast(None, self.inttoptr(value, val_type.make_pointer()), dest_ty);
+            },
+            (false, false) => {
+                // When they are not pointers, we want a transmute (or reinterpret_cast).
+                self.bitcast(value, dest_ty)
+            },
+            (true, true) => self.cx.context.new_cast(None, value, dest_ty),
+            (true, false) => unimplemented!(),
+        }
+    }
+
+    /* Comparisons */
+    fn icmp(&mut self, op: IntPredicate, mut lhs: RValue<'gcc>, mut rhs: RValue<'gcc>) -> RValue<'gcc> {
+        let left_type = lhs.get_type();
+        let right_type = rhs.get_type();
+        if left_type != right_type {
+            // NOTE: because libgccjit cannot compare function pointers.
+            if left_type.is_function_ptr_type().is_some() && right_type.is_function_ptr_type().is_some() {
+                lhs = self.context.new_cast(None, lhs, self.usize_type.make_pointer());
+                rhs = self.context.new_cast(None, rhs, self.usize_type.make_pointer());
+            }
+            // NOTE: hack because we try to cast a vector type to the same vector type.
+            else if format!("{:?}", left_type) != format!("{:?}", right_type) {
+                rhs = self.context.new_cast(None, rhs, left_type);
+            }
+        }
+        self.context.new_comparison(None, op.to_gcc_comparison(), lhs, rhs)
+    }
+
+    fn fcmp(&mut self, op: RealPredicate, lhs: RValue<'gcc>, rhs: RValue<'gcc>) -> RValue<'gcc> {
+        self.context.new_comparison(None, op.to_gcc_comparison(), lhs, rhs)
+    }
+
+    /* Miscellaneous instructions */
+    fn memcpy(&mut self, dst: RValue<'gcc>, dst_align: Align, src: RValue<'gcc>, src_align: Align, size: RValue<'gcc>, flags: MemFlags) {
+        if flags.contains(MemFlags::NONTEMPORAL) {
+            // HACK(nox): This is inefficient but there is no nontemporal memcpy.
+            let val = self.load(src.get_type(), src, src_align);
+            let ptr = self.pointercast(dst, self.type_ptr_to(self.val_ty(val)));
+            self.store_with_flags(val, ptr, dst_align, flags);
+            return;
+        }
+        let size = self.intcast(size, self.type_size_t(), false);
+        let _is_volatile = flags.contains(MemFlags::VOLATILE);
+        let dst = self.pointercast(dst, self.type_i8p());
+        let src = self.pointercast(src, self.type_ptr_to(self.type_void()));
+        let memcpy = self.context.get_builtin_function("memcpy");
+        let block = self.block.expect("block");
+        // TODO(antoyo): handle aligns and is_volatile.
+        block.add_eval(None, self.context.new_call(None, memcpy, &[dst, src, size]));
+    }
+
+    fn memmove(&mut self, dst: RValue<'gcc>, dst_align: Align, src: RValue<'gcc>, src_align: Align, size: RValue<'gcc>, flags: MemFlags) {
+        if flags.contains(MemFlags::NONTEMPORAL) {
+            // HACK(nox): This is inefficient but there is no nontemporal memmove.
+            let val = self.load(src.get_type(), src, src_align);
+            let ptr = self.pointercast(dst, self.type_ptr_to(self.val_ty(val)));
+            self.store_with_flags(val, ptr, dst_align, flags);
+            return;
+        }
+        let size = self.intcast(size, self.type_size_t(), false);
+        let _is_volatile = flags.contains(MemFlags::VOLATILE);
+        let dst = self.pointercast(dst, self.type_i8p());
+        let src = self.pointercast(src, self.type_ptr_to(self.type_void()));
+
+        let memmove = self.context.get_builtin_function("memmove");
+        let block = self.block.expect("block");
+        // TODO(antoyo): handle is_volatile.
+        block.add_eval(None, self.context.new_call(None, memmove, &[dst, src, size]));
+    }
+
+    fn memset(&mut self, ptr: RValue<'gcc>, fill_byte: RValue<'gcc>, size: RValue<'gcc>, _align: Align, flags: MemFlags) {
+        let _is_volatile = flags.contains(MemFlags::VOLATILE);
+        let ptr = self.pointercast(ptr, self.type_i8p());
+        let memset = self.context.get_builtin_function("memset");
+        let block = self.block.expect("block");
+        // TODO(antoyo): handle align and is_volatile.
+        let fill_byte = self.context.new_cast(None, fill_byte, self.i32_type);
+        let size = self.intcast(size, self.type_size_t(), false);
+        block.add_eval(None, self.context.new_call(None, memset, &[ptr, fill_byte, size]));
+    }
+
+    fn select(&mut self, cond: RValue<'gcc>, then_val: RValue<'gcc>, mut else_val: RValue<'gcc>) -> RValue<'gcc> {
+        let func = self.current_func();
+        let variable = func.new_local(None, then_val.get_type(), "selectVar");
+        let then_block = func.new_block("then");
+        let else_block = func.new_block("else");
+        let after_block = func.new_block("after");
+        self.llbb().end_with_conditional(None, cond, then_block, else_block);
+
+        then_block.add_assignment(None, variable, then_val);
+        then_block.end_with_jump(None, after_block);
+
+        if then_val.get_type() != else_val.get_type() {
+            else_val = self.context.new_cast(None, else_val, then_val.get_type());
+        }
+        else_block.add_assignment(None, variable, else_val);
+        else_block.end_with_jump(None, after_block);
+
+        // NOTE: since jumps were added in a place rustc does not expect, the current blocks in the
+        // state need to be updated.
+        self.block = Some(after_block);
+        *self.cx.current_block.borrow_mut() = Some(after_block);
+
+        variable.to_rvalue()
+    }
+
+    #[allow(dead_code)]
+    fn va_arg(&mut self, _list: RValue<'gcc>, _ty: Type<'gcc>) -> RValue<'gcc> {
+        unimplemented!();
+    }
+
+    fn extract_element(&mut self, _vec: RValue<'gcc>, _idx: RValue<'gcc>) -> RValue<'gcc> {
+        unimplemented!();
+    }
+
+    fn vector_splat(&mut self, _num_elts: usize, _elt: RValue<'gcc>) -> RValue<'gcc> {
+        unimplemented!();
+    }
+
+    fn extract_value(&mut self, aggregate_value: RValue<'gcc>, idx: u64) -> RValue<'gcc> {
+        // FIXME(antoyo): it would be better if the API only called this on struct, not on arrays.
+        assert_eq!(idx as usize as u64, idx);
+        let value_type = aggregate_value.get_type();
+
+        if value_type.is_array().is_some() {
+            let index = self.context.new_rvalue_from_long(self.u64_type, i64::try_from(idx).expect("i64::try_from"));
+            let element = self.context.new_array_access(None, aggregate_value, index);
+            element.get_address(None)
+        }
+        else if value_type.is_vector().is_some() {
+            panic!();
+        }
+        else if let Some(pointer_type) = value_type.get_pointee() {
+            if let Some(struct_type) = pointer_type.is_struct() {
+                // NOTE: hack to workaround a limitation of the rustc API: see comment on
+                // CodegenCx.structs_as_pointer
+                aggregate_value.dereference_field(None, struct_type.get_field(idx as i32)).to_rvalue()
+            }
+            else {
+                panic!("Unexpected type {:?}", value_type);
+            }
+        }
+        else if let Some(struct_type) = value_type.is_struct() {
+            aggregate_value.access_field(None, struct_type.get_field(idx as i32)).to_rvalue()
+        }
+        else {
+            panic!("Unexpected type {:?}", value_type);
+        }
+    }
+
+    fn insert_value(&mut self, aggregate_value: RValue<'gcc>, value: RValue<'gcc>, idx: u64) -> RValue<'gcc> {
+        // FIXME(antoyo): it would be better if the API only called this on struct, not on arrays.
+        assert_eq!(idx as usize as u64, idx);
+        let value_type = aggregate_value.get_type();
+
+        let lvalue =
+            if value_type.is_array().is_some() {
+                let index = self.context.new_rvalue_from_long(self.u64_type, i64::try_from(idx).expect("i64::try_from"));
+                self.context.new_array_access(None, aggregate_value, index)
+            }
+            else if value_type.is_vector().is_some() {
+                panic!();
+            }
+            else if let Some(pointer_type) = value_type.get_pointee() {
+                if let Some(struct_type) = pointer_type.is_struct() {
+                    // NOTE: hack to workaround a limitation of the rustc API: see comment on
+                    // CodegenCx.structs_as_pointer
+                    aggregate_value.dereference_field(None, struct_type.get_field(idx as i32))
+                }
+                else {
+                    panic!("Unexpected type {:?}", value_type);
+                }
+            }
+            else {
+                panic!("Unexpected type {:?}", value_type);
+            };
+
+        let lvalue_type = lvalue.to_rvalue().get_type();
+        let value =
+            // NOTE: sometimes, rustc will create a value with the wrong type.
+            if lvalue_type != value.get_type() {
+                self.context.new_cast(None, value, lvalue_type)
+            }
+            else {
+                value
+            };
+
+        self.llbb().add_assignment(None, lvalue, value);
+
+        aggregate_value
+    }
+
+    fn landing_pad(&mut self, _ty: Type<'gcc>, _pers_fn: RValue<'gcc>, _num_clauses: usize) -> RValue<'gcc> {
+        let field1 = self.context.new_field(None, self.u8_type, "landing_pad_field_1");
+        let field2 = self.context.new_field(None, self.i32_type, "landing_pad_field_1");
+        let struct_type = self.context.new_struct_type(None, "landing_pad", &[field1, field2]);
+        self.current_func().new_local(None, struct_type.as_type(), "landing_pad")
+            .to_rvalue()
+        // TODO(antoyo): Properly implement unwinding.
+        // the above is just to make the compilation work as it seems
+        // rustc_codegen_ssa now calls the unwinding builder methods even on panic=abort.
+    }
+
+    fn set_cleanup(&mut self, _landing_pad: RValue<'gcc>) {
+        // TODO(antoyo)
+    }
+
+    fn resume(&mut self, _exn: RValue<'gcc>) -> RValue<'gcc> {
+        unimplemented!();
+    }
+
+    fn cleanup_pad(&mut self, _parent: Option<RValue<'gcc>>, _args: &[RValue<'gcc>]) -> Funclet {
+        unimplemented!();
+    }
+
+    fn cleanup_ret(&mut self, _funclet: &Funclet, _unwind: Option<Block<'gcc>>) -> RValue<'gcc> {
+        unimplemented!();
+    }
+
+    fn catch_pad(&mut self, _parent: RValue<'gcc>, _args: &[RValue<'gcc>]) -> Funclet {
+        unimplemented!();
+    }
+
+    fn catch_switch(&mut self, _parent: Option<RValue<'gcc>>, _unwind: Option<Block<'gcc>>, _num_handlers: usize) -> RValue<'gcc> {
+        unimplemented!();
+    }
+
+    fn add_handler(&mut self, _catch_switch: RValue<'gcc>, _handler: Block<'gcc>) {
+        unimplemented!();
+    }
+
+    fn set_personality_fn(&mut self, _personality: RValue<'gcc>) {
+        // TODO(antoyo)
+    }
+
+    // Atomic Operations
+    fn atomic_cmpxchg(&mut self, dst: RValue<'gcc>, cmp: RValue<'gcc>, src: RValue<'gcc>, order: AtomicOrdering, failure_order: AtomicOrdering, weak: bool) -> RValue<'gcc> {
+        let expected = self.current_func().new_local(None, cmp.get_type(), "expected");
+        self.llbb().add_assignment(None, expected, cmp);
+        let success = self.compare_exchange(dst, expected, src, order, failure_order, weak);
+
+        let pair_type = self.cx.type_struct(&[src.get_type(), self.bool_type], false);
+        let result = self.current_func().new_local(None, pair_type, "atomic_cmpxchg_result");
+        let align = Align::from_bits(64).expect("align"); // TODO(antoyo): use good align.
+
+        let value_type = result.to_rvalue().get_type();
+        if let Some(struct_type) = value_type.is_struct() {
+            self.store(success, result.access_field(None, struct_type.get_field(1)).get_address(None), align);
+            // NOTE: since success contains the call to the intrinsic, it must be stored before
+            // expected so that we store expected after the call.
+            self.store(expected.to_rvalue(), result.access_field(None, struct_type.get_field(0)).get_address(None), align);
+        }
+        // TODO(antoyo): handle when value is not a struct.
+
+        result.to_rvalue()
+    }
+
+    fn atomic_rmw(&mut self, op: AtomicRmwBinOp, dst: RValue<'gcc>, src: RValue<'gcc>, order: AtomicOrdering) -> RValue<'gcc> {
+        let size = self.cx.int_width(src.get_type()) / 8;
+        let name =
+            match op {
+                AtomicRmwBinOp::AtomicXchg => format!("__atomic_exchange_{}", size),
+                AtomicRmwBinOp::AtomicAdd => format!("__atomic_fetch_add_{}", size),
+                AtomicRmwBinOp::AtomicSub => format!("__atomic_fetch_sub_{}", size),
+                AtomicRmwBinOp::AtomicAnd => format!("__atomic_fetch_and_{}", size),
+                AtomicRmwBinOp::AtomicNand => format!("__atomic_fetch_nand_{}", size),
+                AtomicRmwBinOp::AtomicOr => format!("__atomic_fetch_or_{}", size),
+                AtomicRmwBinOp::AtomicXor => format!("__atomic_fetch_xor_{}", size),
+                AtomicRmwBinOp::AtomicMax => return self.atomic_extremum(ExtremumOperation::Max, dst, src, order),
+                AtomicRmwBinOp::AtomicMin => return self.atomic_extremum(ExtremumOperation::Min, dst, src, order),
+                AtomicRmwBinOp::AtomicUMax => return self.atomic_extremum(ExtremumOperation::Max, dst, src, order),
+                AtomicRmwBinOp::AtomicUMin => return self.atomic_extremum(ExtremumOperation::Min, dst, src, order),
+            };
+
+
+        let atomic_function = self.context.get_builtin_function(name);
+        let order = self.context.new_rvalue_from_int(self.i32_type, order.to_gcc());
+
+        let void_ptr_type = self.context.new_type::<*mut ()>();
+        let volatile_void_ptr_type = void_ptr_type.make_volatile();
+        let dst = self.context.new_cast(None, dst, volatile_void_ptr_type);
+        // FIXME(antoyo): not sure why, but we have the wrong type here.
+        let new_src_type = atomic_function.get_param(1).to_rvalue().get_type();
+        let src = self.context.new_cast(None, src, new_src_type);
+        let res = self.context.new_call(None, atomic_function, &[dst, src, order]);
+        self.context.new_cast(None, res, src.get_type())
+    }
+
+    fn atomic_fence(&mut self, order: AtomicOrdering, scope: SynchronizationScope) {
+        let name =
+            match scope {
+                SynchronizationScope::SingleThread => "__atomic_signal_fence",
+                SynchronizationScope::CrossThread => "__atomic_thread_fence",
+            };
+        let thread_fence = self.context.get_builtin_function(name);
+        let order = self.context.new_rvalue_from_int(self.i32_type, order.to_gcc());
+        self.llbb().add_eval(None, self.context.new_call(None, thread_fence, &[order]));
+    }
+
+    fn set_invariant_load(&mut self, load: RValue<'gcc>) {
+        // NOTE: Hack to consider vtable function pointer as non-global-variable function pointer.
+        self.normal_function_addresses.borrow_mut().insert(load);
+        // TODO(antoyo)
+    }
+
+    fn lifetime_start(&mut self, _ptr: RValue<'gcc>, _size: Size) {
+        // TODO(antoyo)
+    }
+
+    fn lifetime_end(&mut self, _ptr: RValue<'gcc>, _size: Size) {
+        // TODO(antoyo)
+    }
+
+    fn call(&mut self, _typ: Type<'gcc>, func: RValue<'gcc>, args: &[RValue<'gcc>], funclet: Option<&Funclet>) -> RValue<'gcc> {
+        // FIXME(antoyo): remove when having a proper API.
+        let gcc_func = unsafe { std::mem::transmute(func) };
+        if self.functions.borrow().values().find(|value| **value == gcc_func).is_some() {
+            self.function_call(func, args, funclet)
+        }
+        else {
+            // If it's a not function that was defined, it's a function pointer.
+            self.function_ptr_call(func, args, funclet)
+        }
+    }
+
+    fn zext(&mut self, value: RValue<'gcc>, dest_typ: Type<'gcc>) -> RValue<'gcc> {
+        // FIXME(antoyo): this does not zero-extend.
+        if value.get_type().is_bool() && dest_typ.is_i8(&self.cx) {
+            // FIXME(antoyo): hack because base::from_immediate converts i1 to i8.
+            // Fix the code in codegen_ssa::base::from_immediate.
+            return value;
+        }
+        self.context.new_cast(None, value, dest_typ)
+    }
+
+    fn cx(&self) -> &CodegenCx<'gcc, 'tcx> {
+        self.cx
+    }
+
+    fn do_not_inline(&mut self, _llret: RValue<'gcc>) {
+        unimplemented!();
+    }
+
+    fn set_span(&mut self, _span: Span) {}
+
+    fn from_immediate(&mut self, val: Self::Value) -> Self::Value {
+        if self.cx().val_ty(val) == self.cx().type_i1() {
+            self.zext(val, self.cx().type_i8())
+        }
+        else {
+            val
+        }
+    }
+
+    fn to_immediate_scalar(&mut self, val: Self::Value, scalar: abi::Scalar) -> Self::Value {
+        if scalar.is_bool() {
+            return self.trunc(val, self.cx().type_i1());
+        }
+        val
+    }
+
+    fn fptoui_sat(&mut self, _val: RValue<'gcc>, _dest_ty: Type<'gcc>) -> Option<RValue<'gcc>> {
+        None
+    }
+
+    fn fptosi_sat(&mut self, _val: RValue<'gcc>, _dest_ty: Type<'gcc>) -> Option<RValue<'gcc>> {
+        None
+    }
+
+    fn instrprof_increment(&mut self, _fn_name: RValue<'gcc>, _hash: RValue<'gcc>, _num_counters: RValue<'gcc>, _index: RValue<'gcc>) {
+        unimplemented!();
+    }
+}
+
+impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
+    pub fn shuffle_vector(&mut self, v1: RValue<'gcc>, v2: RValue<'gcc>, mask: RValue<'gcc>) -> RValue<'gcc> {
+        let return_type = v1.get_type();
+        let params = [
+            self.context.new_parameter(None, return_type, "v1"),
+            self.context.new_parameter(None, return_type, "v2"),
+            self.context.new_parameter(None, mask.get_type(), "mask"),
+        ];
+        let shuffle = self.context.new_function(None, FunctionType::Extern, return_type, &params, "_mm_shuffle_epi8", false);
+        self.context.new_call(None, shuffle, &[v1, v2, mask])
+    }
+}
+
+impl<'a, 'gcc, 'tcx> StaticBuilderMethods for Builder<'a, 'gcc, 'tcx> {
+    fn get_static(&mut self, def_id: DefId) -> RValue<'gcc> {
+        // Forward to the `get_static` method of `CodegenCx`
+        self.cx().get_static(def_id).get_address(None)
+    }
+}
+
+impl<'tcx> HasParamEnv<'tcx> for Builder<'_, '_, 'tcx> {
+    fn param_env(&self) -> ParamEnv<'tcx> {
+        self.cx.param_env()
+    }
+}
+
+impl<'tcx> HasTargetSpec for Builder<'_, '_, 'tcx> {
+    fn target_spec(&self) -> &Target {
+        &self.cx.target_spec()
+    }
+}
+
+trait ToGccComp {
+    fn to_gcc_comparison(&self) -> ComparisonOp;
+}
+
+impl ToGccComp for IntPredicate {
+    fn to_gcc_comparison(&self) -> ComparisonOp {
+        match *self {
+            IntPredicate::IntEQ => ComparisonOp::Equals,
+            IntPredicate::IntNE => ComparisonOp::NotEquals,
+            IntPredicate::IntUGT => ComparisonOp::GreaterThan,
+            IntPredicate::IntUGE => ComparisonOp::GreaterThanEquals,
+            IntPredicate::IntULT => ComparisonOp::LessThan,
+            IntPredicate::IntULE => ComparisonOp::LessThanEquals,
+            IntPredicate::IntSGT => ComparisonOp::GreaterThan,
+            IntPredicate::IntSGE => ComparisonOp::GreaterThanEquals,
+            IntPredicate::IntSLT => ComparisonOp::LessThan,
+            IntPredicate::IntSLE => ComparisonOp::LessThanEquals,
+        }
+    }
+}
+
+impl ToGccComp for RealPredicate {
+    fn to_gcc_comparison(&self) -> ComparisonOp {
+        // TODO(antoyo): check that ordered vs non-ordered is respected.
+        match *self {
+            RealPredicate::RealPredicateFalse => unreachable!(),
+            RealPredicate::RealOEQ => ComparisonOp::Equals,
+            RealPredicate::RealOGT => ComparisonOp::GreaterThan,
+            RealPredicate::RealOGE => ComparisonOp::GreaterThanEquals,
+            RealPredicate::RealOLT => ComparisonOp::LessThan,
+            RealPredicate::RealOLE => ComparisonOp::LessThanEquals,
+            RealPredicate::RealONE => ComparisonOp::NotEquals,
+            RealPredicate::RealORD => unreachable!(),
+            RealPredicate::RealUNO => unreachable!(),
+            RealPredicate::RealUEQ => ComparisonOp::Equals,
+            RealPredicate::RealUGT => ComparisonOp::GreaterThan,
+            RealPredicate::RealUGE => ComparisonOp::GreaterThan,
+            RealPredicate::RealULT => ComparisonOp::LessThan,
+            RealPredicate::RealULE => ComparisonOp::LessThan,
+            RealPredicate::RealUNE => ComparisonOp::NotEquals,
+            RealPredicate::RealPredicateTrue => unreachable!(),
+        }
+    }
+}
+
+#[repr(C)]
+#[allow(non_camel_case_types)]
+enum MemOrdering {
+    __ATOMIC_RELAXED,
+    __ATOMIC_CONSUME,
+    __ATOMIC_ACQUIRE,
+    __ATOMIC_RELEASE,
+    __ATOMIC_ACQ_REL,
+    __ATOMIC_SEQ_CST,
+}
+
+trait ToGccOrdering {
+    fn to_gcc(self) -> i32;
+}
+
+impl ToGccOrdering for AtomicOrdering {
+    fn to_gcc(self) -> i32 {
+        use MemOrdering::*;
+
+        let ordering =
+            match self {
+                AtomicOrdering::NotAtomic => __ATOMIC_RELAXED, // TODO(antoyo): check if that's the same.
+                AtomicOrdering::Unordered => __ATOMIC_RELAXED,
+                AtomicOrdering::Monotonic => __ATOMIC_RELAXED, // TODO(antoyo): check if that's the same.
+                AtomicOrdering::Acquire => __ATOMIC_ACQUIRE,
+                AtomicOrdering::Release => __ATOMIC_RELEASE,
+                AtomicOrdering::AcquireRelease => __ATOMIC_ACQ_REL,
+                AtomicOrdering::SequentiallyConsistent => __ATOMIC_SEQ_CST,
+            };
+        ordering as i32
+    }
+}
diff --git a/compiler/rustc_codegen_gcc/src/callee.rs b/compiler/rustc_codegen_gcc/src/callee.rs
new file mode 100644
index 00000000000..76419b103d0
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/callee.rs
@@ -0,0 +1,77 @@
+use gccjit::{FunctionType, RValue};
+use rustc_codegen_ssa::traits::BaseTypeMethods;
+use rustc_middle::ty::{self, Instance, TypeFoldable};
+use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt};
+
+use crate::abi::FnAbiGccExt;
+use crate::context::CodegenCx;
+
+/// Codegens a reference to a fn/method item, monomorphizing and
+/// inlining as it goes.
+///
+/// # Parameters
+///
+/// - `cx`: the crate context
+/// - `instance`: the instance to be instantiated
+pub fn get_fn<'gcc, 'tcx>(cx: &CodegenCx<'gcc, 'tcx>, instance: Instance<'tcx>) -> RValue<'gcc> {
+    let tcx = cx.tcx();
+
+    assert!(!instance.substs.needs_infer());
+    assert!(!instance.substs.has_escaping_bound_vars());
+
+    if let Some(&func) = cx.function_instances.borrow().get(&instance) {
+        return func;
+    }
+
+    let sym = tcx.symbol_name(instance).name;
+
+    let fn_abi = cx.fn_abi_of_instance(instance, ty::List::empty());
+
+    let func =
+        if let Some(func) = cx.get_declared_value(&sym) {
+            // Create a fn pointer with the new signature.
+            let ptrty = fn_abi.ptr_to_gcc_type(cx);
+
+            // This is subtle and surprising, but sometimes we have to bitcast
+            // the resulting fn pointer.  The reason has to do with external
+            // functions.  If you have two crates that both bind the same C
+            // library, they may not use precisely the same types: for
+            // example, they will probably each declare their own structs,
+            // which are distinct types from LLVM's point of view (nominal
+            // types).
+            //
+            // Now, if those two crates are linked into an application, and
+            // they contain inlined code, you can wind up with a situation
+            // where both of those functions wind up being loaded into this
+            // application simultaneously. In that case, the same function
+            // (from LLVM's point of view) requires two types. But of course
+            // LLVM won't allow one function to have two types.
+            //
+            // What we currently do, therefore, is declare the function with
+            // one of the two types (whichever happens to come first) and then
+            // bitcast as needed when the function is referenced to make sure
+            // it has the type we expect.
+            //
+            // This can occur on either a crate-local or crate-external
+            // reference. It also occurs when testing libcore and in some
+            // other weird situations. Annoying.
+            if cx.val_ty(func) != ptrty {
+                // TODO(antoyo): cast the pointer.
+                func
+            }
+            else {
+                func
+            }
+        }
+        else {
+            cx.linkage.set(FunctionType::Extern);
+            let func = cx.declare_fn(&sym, &fn_abi);
+
+            // TODO(antoyo): set linkage and attributes.
+            func
+        };
+
+    cx.function_instances.borrow_mut().insert(instance, func);
+
+    func
+}
diff --git a/compiler/rustc_codegen_gcc/src/common.rs b/compiler/rustc_codegen_gcc/src/common.rs
new file mode 100644
index 00000000000..bda08b653f0
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/common.rs
@@ -0,0 +1,450 @@
+use std::convert::TryFrom;
+use std::convert::TryInto;
+
+use gccjit::LValue;
+use gccjit::{Block, CType, RValue, Type, ToRValue};
+use rustc_codegen_ssa::mir::place::PlaceRef;
+use rustc_codegen_ssa::traits::{
+    BaseTypeMethods,
+    ConstMethods,
+    DerivedTypeMethods,
+    MiscMethods,
+    StaticMethods,
+};
+use rustc_middle::mir::Mutability;
+use rustc_middle::ty::ScalarInt;
+use rustc_middle::ty::layout::{TyAndLayout, LayoutOf};
+use rustc_middle::mir::interpret::{Allocation, GlobalAlloc, Scalar};
+use rustc_span::Symbol;
+use rustc_target::abi::{self, HasDataLayout, Pointer, Size};
+
+use crate::consts::const_alloc_to_gcc;
+use crate::context::CodegenCx;
+use crate::type_of::LayoutGccExt;
+
+impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
+    pub fn const_bytes(&self, bytes: &[u8]) -> RValue<'gcc> {
+        bytes_in_context(self, bytes)
+    }
+
+    fn const_cstr(&self, symbol: Symbol, _null_terminated: bool) -> LValue<'gcc> {
+        // TODO(antoyo): handle null_terminated.
+        if let Some(&value) = self.const_cstr_cache.borrow().get(&symbol) {
+            return value;
+        }
+
+        let global = self.global_string(&*symbol.as_str());
+
+        self.const_cstr_cache.borrow_mut().insert(symbol, global);
+        global
+    }
+
+    fn global_string(&self, string: &str) -> LValue<'gcc> {
+        // TODO(antoyo): handle non-null-terminated strings.
+        let string = self.context.new_string_literal(&*string);
+        let sym = self.generate_local_symbol_name("str");
+        let global = self.declare_private_global(&sym, self.val_ty(string));
+        global.global_set_initializer_value(string);
+        global
+        // TODO(antoyo): set linkage.
+    }
+
+    pub fn inttoptr(&self, block: Block<'gcc>, value: RValue<'gcc>, dest_ty: Type<'gcc>) -> RValue<'gcc> {
+        let func = block.get_function();
+        let local = func.new_local(None, value.get_type(), "intLocal");
+        block.add_assignment(None, local, value);
+        let value_address = local.get_address(None);
+
+        let ptr = self.context.new_cast(None, value_address, dest_ty.make_pointer());
+        ptr.dereference(None).to_rvalue()
+    }
+
+    pub fn ptrtoint(&self, block: Block<'gcc>, value: RValue<'gcc>, dest_ty: Type<'gcc>) -> RValue<'gcc> {
+        // TODO(antoyo): when libgccjit allow casting from pointer to int, remove this.
+        let func = block.get_function();
+        let local = func.new_local(None, value.get_type(), "ptrLocal");
+        block.add_assignment(None, local, value);
+        let ptr_address = local.get_address(None);
+
+        let ptr = self.context.new_cast(None, ptr_address, dest_ty.make_pointer());
+        ptr.dereference(None).to_rvalue()
+    }
+}
+
+pub fn bytes_in_context<'gcc, 'tcx>(cx: &CodegenCx<'gcc, 'tcx>, bytes: &[u8]) -> RValue<'gcc> {
+    let context = &cx.context;
+    let byte_type = context.new_type::<u8>();
+    let typ = context.new_array_type(None, byte_type, bytes.len() as i32);
+    let elements: Vec<_> =
+        bytes.iter()
+        .map(|&byte| context.new_rvalue_from_int(byte_type, byte as i32))
+        .collect();
+    context.new_rvalue_from_array(None, typ, &elements)
+}
+
+pub fn type_is_pointer<'gcc>(typ: Type<'gcc>) -> bool {
+    typ.get_pointee().is_some()
+}
+
+impl<'gcc, 'tcx> ConstMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
+    fn const_null(&self, typ: Type<'gcc>) -> RValue<'gcc> {
+        if type_is_pointer(typ) {
+            self.context.new_null(typ)
+        }
+        else {
+            self.const_int(typ, 0)
+        }
+    }
+
+    fn const_undef(&self, typ: Type<'gcc>) -> RValue<'gcc> {
+        let local = self.current_func.borrow().expect("func")
+            .new_local(None, typ, "undefined");
+        if typ.is_struct().is_some() {
+            // NOTE: hack to workaround a limitation of the rustc API: see comment on
+            // CodegenCx.structs_as_pointer
+            let pointer = local.get_address(None);
+            self.structs_as_pointer.borrow_mut().insert(pointer);
+            pointer
+        }
+        else {
+            local.to_rvalue()
+        }
+    }
+
+    fn const_int(&self, typ: Type<'gcc>, int: i64) -> RValue<'gcc> {
+        self.context.new_rvalue_from_long(typ, i64::try_from(int).expect("i64::try_from"))
+    }
+
+    fn const_uint(&self, typ: Type<'gcc>, int: u64) -> RValue<'gcc> {
+        self.context.new_rvalue_from_long(typ, u64::try_from(int).expect("u64::try_from") as i64)
+    }
+
+    fn const_uint_big(&self, typ: Type<'gcc>, num: u128) -> RValue<'gcc> {
+        let num64: Result<i64, _> = num.try_into();
+        if let Ok(num) = num64 {
+            // FIXME(antoyo): workaround for a bug where libgccjit is expecting a constant.
+            // The operations >> 64 and | low are making the normal case a non-constant.
+            return self.context.new_rvalue_from_long(typ, num as i64);
+        }
+
+        if num >> 64 != 0 {
+            // FIXME(antoyo): use a new function new_rvalue_from_unsigned_long()?
+            let low = self.context.new_rvalue_from_long(self.u64_type, num as u64 as i64);
+            let high = self.context.new_rvalue_from_long(typ, (num >> 64) as u64 as i64);
+
+            let sixty_four = self.context.new_rvalue_from_long(typ, 64);
+            (high << sixty_four) | self.context.new_cast(None, low, typ)
+        }
+        else if typ.is_i128(self) {
+            let num = self.context.new_rvalue_from_long(self.u64_type, num as u64 as i64);
+            self.context.new_cast(None, num, typ)
+        }
+        else {
+            self.context.new_rvalue_from_long(typ, num as u64 as i64)
+        }
+    }
+
+    fn const_bool(&self, val: bool) -> RValue<'gcc> {
+        self.const_uint(self.type_i1(), val as u64)
+    }
+
+    fn const_i32(&self, i: i32) -> RValue<'gcc> {
+        self.const_int(self.type_i32(), i as i64)
+    }
+
+    fn const_u32(&self, i: u32) -> RValue<'gcc> {
+        self.const_uint(self.type_u32(), i as u64)
+    }
+
+    fn const_u64(&self, i: u64) -> RValue<'gcc> {
+        self.const_uint(self.type_u64(), i)
+    }
+
+    fn const_usize(&self, i: u64) -> RValue<'gcc> {
+        let bit_size = self.data_layout().pointer_size.bits();
+        if bit_size < 64 {
+            // make sure it doesn't overflow
+            assert!(i < (1 << bit_size));
+        }
+
+        self.const_uint(self.usize_type, i)
+    }
+
+    fn const_u8(&self, _i: u8) -> RValue<'gcc> {
+        unimplemented!();
+    }
+
+    fn const_real(&self, _t: Type<'gcc>, _val: f64) -> RValue<'gcc> {
+        unimplemented!();
+    }
+
+    fn const_str(&self, s: Symbol) -> (RValue<'gcc>, RValue<'gcc>) {
+        let len = s.as_str().len();
+        let cs = self.const_ptrcast(self.const_cstr(s, false).get_address(None),
+            self.type_ptr_to(self.layout_of(self.tcx.types.str_).gcc_type(self, true)),
+        );
+        (cs, self.const_usize(len as u64))
+    }
+
+    fn const_struct(&self, values: &[RValue<'gcc>], packed: bool) -> RValue<'gcc> {
+        let fields: Vec<_> = values.iter()
+            .map(|value| value.get_type())
+            .collect();
+        // TODO(antoyo): cache the type? It's anonymous, so probably not.
+        let typ = self.type_struct(&fields, packed);
+        let struct_type = typ.is_struct().expect("struct type");
+        self.context.new_rvalue_from_struct(None, struct_type, values)
+    }
+
+    fn const_to_opt_uint(&self, _v: RValue<'gcc>) -> Option<u64> {
+        // TODO(antoyo)
+        None
+    }
+
+    fn const_to_opt_u128(&self, _v: RValue<'gcc>, _sign_ext: bool) -> Option<u128> {
+        // TODO(antoyo)
+        None
+    }
+
+    fn scalar_to_backend(&self, cv: Scalar, layout: abi::Scalar, ty: Type<'gcc>) -> RValue<'gcc> {
+        let bitsize = if layout.is_bool() { 1 } else { layout.value.size(self).bits() };
+        match cv {
+            Scalar::Int(ScalarInt::ZST) => {
+                assert_eq!(0, layout.value.size(self).bytes());
+                self.const_undef(self.type_ix(0))
+            }
+            Scalar::Int(int) => {
+                let data = int.assert_bits(layout.value.size(self));
+
+                // FIXME(antoyo): there's some issues with using the u128 code that follows, so hard-code
+                // the paths for floating-point values.
+                if ty == self.float_type {
+                    return self.context.new_rvalue_from_double(ty, f32::from_bits(data as u32) as f64);
+                }
+                else if ty == self.double_type {
+                    return self.context.new_rvalue_from_double(ty, f64::from_bits(data as u64));
+                }
+
+                let value = self.const_uint_big(self.type_ix(bitsize), data);
+                if layout.value == Pointer {
+                    self.inttoptr(self.current_block.borrow().expect("block"), value, ty)
+                } else {
+                    self.const_bitcast(value, ty)
+                }
+            }
+            Scalar::Ptr(ptr, _size) => {
+                let (alloc_id, offset) = ptr.into_parts();
+                let base_addr =
+                    match self.tcx.global_alloc(alloc_id) {
+                        GlobalAlloc::Memory(alloc) => {
+                            let init = const_alloc_to_gcc(self, alloc);
+                            let value =
+                                match alloc.mutability {
+                                    Mutability::Mut => self.static_addr_of_mut(init, alloc.align, None),
+                                    _ => self.static_addr_of(init, alloc.align, None),
+                                };
+                            if !self.sess().fewer_names() {
+                                // TODO(antoyo): set value name.
+                            }
+                            value
+                        },
+                        GlobalAlloc::Function(fn_instance) => {
+                            self.get_fn_addr(fn_instance)
+                        },
+                        GlobalAlloc::Static(def_id) => {
+                            assert!(self.tcx.is_static(def_id));
+                            self.get_static(def_id).get_address(None)
+                        },
+                    };
+                let ptr_type = base_addr.get_type();
+                let base_addr = self.const_bitcast(base_addr, self.usize_type);
+                let offset = self.context.new_rvalue_from_long(self.usize_type, offset.bytes() as i64);
+                let ptr = self.const_bitcast(base_addr + offset, ptr_type);
+                if layout.value != Pointer {
+                    self.const_bitcast(ptr.dereference(None).to_rvalue(), ty)
+                }
+                else {
+                    self.const_bitcast(ptr, ty)
+                }
+            }
+        }
+    }
+
+    fn const_data_from_alloc(&self, alloc: &Allocation) -> Self::Value {
+        const_alloc_to_gcc(self, alloc)
+    }
+
+    fn from_const_alloc(&self, layout: TyAndLayout<'tcx>, alloc: &Allocation, offset: Size) -> PlaceRef<'tcx, RValue<'gcc>> {
+        assert_eq!(alloc.align, layout.align.abi);
+        let ty = self.type_ptr_to(layout.gcc_type(self, true));
+        let value =
+            if layout.size == Size::ZERO {
+                let value = self.const_usize(alloc.align.bytes());
+                self.context.new_cast(None, value, ty)
+            }
+            else {
+                let init = const_alloc_to_gcc(self, alloc);
+                let base_addr = self.static_addr_of(init, alloc.align, None);
+
+                let array = self.const_bitcast(base_addr, self.type_i8p());
+                let value = self.context.new_array_access(None, array, self.const_usize(offset.bytes())).get_address(None);
+                self.const_bitcast(value, ty)
+            };
+        PlaceRef::new_sized(value, layout)
+    }
+
+    fn const_ptrcast(&self, val: RValue<'gcc>, ty: Type<'gcc>) -> RValue<'gcc> {
+        self.context.new_cast(None, val, ty)
+    }
+}
+
+pub trait SignType<'gcc, 'tcx> {
+    fn is_signed(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool;
+    fn is_unsigned(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool;
+    fn to_signed(&self, cx: &CodegenCx<'gcc, 'tcx>) -> Type<'gcc>;
+    fn to_unsigned(&self, cx: &CodegenCx<'gcc, 'tcx>) -> Type<'gcc>;
+}
+
+impl<'gcc, 'tcx> SignType<'gcc, 'tcx> for Type<'gcc> {
+    fn is_signed(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool {
+        self.is_i8(cx) || self.is_i16(cx) || self.is_i32(cx) || self.is_i64(cx) || self.is_i128(cx)
+    }
+
+    fn is_unsigned(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool {
+        self.is_u8(cx) || self.is_u16(cx) || self.is_u32(cx) || self.is_u64(cx) || self.is_u128(cx)
+    }
+
+    fn to_signed(&self, cx: &CodegenCx<'gcc, 'tcx>) -> Type<'gcc> {
+        if self.is_u8(cx) {
+            cx.i8_type
+        }
+        else if self.is_u16(cx) {
+            cx.i16_type
+        }
+        else if self.is_u32(cx) {
+            cx.i32_type
+        }
+        else if self.is_u64(cx) {
+            cx.i64_type
+        }
+        else if self.is_u128(cx) {
+            cx.i128_type
+        }
+        else {
+            self.clone()
+        }
+    }
+
+    fn to_unsigned(&self, cx: &CodegenCx<'gcc, 'tcx>) -> Type<'gcc> {
+        if self.is_i8(cx) {
+            cx.u8_type
+        }
+        else if self.is_i16(cx) {
+            cx.u16_type
+        }
+        else if self.is_i32(cx) {
+            cx.u32_type
+        }
+        else if self.is_i64(cx) {
+            cx.u64_type
+        }
+        else if self.is_i128(cx) {
+            cx.u128_type
+        }
+        else {
+            self.clone()
+        }
+    }
+}
+
+pub trait TypeReflection<'gcc, 'tcx>  {
+    fn is_uchar(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool;
+    fn is_ushort(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool;
+    fn is_uint(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool;
+    fn is_ulong(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool;
+    fn is_ulonglong(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool;
+
+    fn is_i8(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool;
+    fn is_u8(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool;
+    fn is_i16(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool;
+    fn is_u16(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool;
+    fn is_i32(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool;
+    fn is_u32(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool;
+    fn is_i64(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool;
+    fn is_u64(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool;
+    fn is_i128(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool;
+    fn is_u128(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool;
+
+    fn is_f32(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool;
+    fn is_f64(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool;
+}
+
+impl<'gcc, 'tcx> TypeReflection<'gcc, 'tcx> for Type<'gcc> {
+    fn is_uchar(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool {
+        self.unqualified() == cx.u8_type
+    }
+
+    fn is_ushort(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool {
+        self.unqualified() == cx.u16_type
+    }
+
+    fn is_uint(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool {
+        self.unqualified() == cx.uint_type
+    }
+
+    fn is_ulong(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool {
+        self.unqualified() == cx.ulong_type
+    }
+
+    fn is_ulonglong(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool {
+        self.unqualified() == cx.ulonglong_type
+    }
+
+    fn is_i8(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool {
+        self.unqualified() == cx.i8_type
+    }
+
+    fn is_u8(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool {
+        self.unqualified() == cx.u8_type
+    }
+
+    fn is_i16(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool {
+        self.unqualified() == cx.i16_type
+    }
+
+    fn is_u16(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool {
+        self.unqualified() == cx.u16_type
+    }
+
+    fn is_i32(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool {
+        self.unqualified() == cx.i32_type
+    }
+
+    fn is_u32(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool {
+        self.unqualified() == cx.u32_type
+    }
+
+    fn is_i64(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool {
+        self.unqualified() == cx.i64_type
+    }
+
+    fn is_u64(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool {
+        self.unqualified() == cx.u64_type
+    }
+
+    fn is_i128(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool {
+        self.unqualified() == cx.context.new_c_type(CType::Int128t)
+    }
+
+    fn is_u128(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool {
+        self.unqualified() == cx.context.new_c_type(CType::UInt128t)
+    }
+
+    fn is_f32(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool {
+        self.unqualified() == cx.context.new_type::<f32>()
+    }
+
+    fn is_f64(&self, cx: &CodegenCx<'gcc, 'tcx>) -> bool {
+        self.unqualified() == cx.context.new_type::<f64>()
+    }
+}
diff --git a/compiler/rustc_codegen_gcc/src/consts.rs b/compiler/rustc_codegen_gcc/src/consts.rs
new file mode 100644
index 00000000000..205498acc31
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/consts.rs
@@ -0,0 +1,390 @@
+use gccjit::{LValue, RValue, ToRValue, Type};
+use rustc_codegen_ssa::traits::{BaseTypeMethods, ConstMethods, DerivedTypeMethods, StaticMethods};
+use rustc_hir as hir;
+use rustc_hir::Node;
+use rustc_middle::{bug, span_bug};
+use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
+use rustc_middle::mir::mono::MonoItem;
+use rustc_middle::ty::{self, Instance, Ty};
+use rustc_middle::ty::layout::LayoutOf;
+use rustc_middle::mir::interpret::{self, Allocation, ErrorHandled, Scalar as InterpScalar, read_target_uint};
+use rustc_span::Span;
+use rustc_span::def_id::DefId;
+use rustc_target::abi::{self, Align, HasDataLayout, Primitive, Size, WrappingRange};
+
+use crate::base;
+use crate::context::CodegenCx;
+use crate::type_of::LayoutGccExt;
+
+impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
+    pub fn const_bitcast(&self, value: RValue<'gcc>, typ: Type<'gcc>) -> RValue<'gcc> {
+        if value.get_type() == self.bool_type.make_pointer() {
+            if let Some(pointee) = typ.get_pointee() {
+                if pointee.is_vector().is_some() {
+                    panic!()
+                }
+            }
+        }
+        self.context.new_bitcast(None, value, typ)
+    }
+}
+
+impl<'gcc, 'tcx> StaticMethods for CodegenCx<'gcc, 'tcx> {
+    fn static_addr_of(&self, cv: RValue<'gcc>, align: Align, kind: Option<&str>) -> RValue<'gcc> {
+        if let Some(global_value) = self.const_globals.borrow().get(&cv) {
+            // TODO(antoyo): upgrade alignment.
+            return *global_value;
+        }
+        let global_value = self.static_addr_of_mut(cv, align, kind);
+        // TODO(antoyo): set global constant.
+        self.const_globals.borrow_mut().insert(cv, global_value);
+        global_value
+    }
+
+    fn codegen_static(&self, def_id: DefId, is_mutable: bool) {
+        let attrs = self.tcx.codegen_fn_attrs(def_id);
+
+        let value =
+            match codegen_static_initializer(&self, def_id) {
+                Ok((value, _)) => value,
+                // Error has already been reported
+                Err(_) => return,
+            };
+
+        let global = self.get_static(def_id);
+
+        // boolean SSA values are i1, but they have to be stored in i8 slots,
+        // otherwise some LLVM optimization passes don't work as expected
+        let val_llty = self.val_ty(value);
+        let value =
+            if val_llty == self.type_i1() {
+                unimplemented!();
+            }
+            else {
+                value
+            };
+
+        let instance = Instance::mono(self.tcx, def_id);
+        let ty = instance.ty(self.tcx, ty::ParamEnv::reveal_all());
+        let gcc_type = self.layout_of(ty).gcc_type(self, true);
+
+        // TODO(antoyo): set alignment.
+
+        let value =
+            if value.get_type() != gcc_type {
+                self.context.new_bitcast(None, value, gcc_type)
+            }
+            else {
+                value
+            };
+        global.global_set_initializer_value(value);
+
+        // As an optimization, all shared statics which do not have interior
+        // mutability are placed into read-only memory.
+        if !is_mutable {
+            if self.type_is_freeze(ty) {
+                // TODO(antoyo): set global constant.
+            }
+        }
+
+        if attrs.flags.contains(CodegenFnAttrFlags::THREAD_LOCAL) {
+            // Do not allow LLVM to change the alignment of a TLS on macOS.
+            //
+            // By default a global's alignment can be freely increased.
+            // This allows LLVM to generate more performant instructions
+            // e.g., using load-aligned into a SIMD register.
+            //
+            // However, on macOS 10.10 or below, the dynamic linker does not
+            // respect any alignment given on the TLS (radar 24221680).
+            // This will violate the alignment assumption, and causing segfault at runtime.
+            //
+            // This bug is very easy to trigger. In `println!` and `panic!`,
+            // the `LOCAL_STDOUT`/`LOCAL_STDERR` handles are stored in a TLS,
+            // which the values would be `mem::replace`d on initialization.
+            // The implementation of `mem::replace` will use SIMD
+            // whenever the size is 32 bytes or higher. LLVM notices SIMD is used
+            // and tries to align `LOCAL_STDOUT`/`LOCAL_STDERR` to a 32-byte boundary,
+            // which macOS's dyld disregarded and causing crashes
+            // (see issues #51794, #51758, #50867, #48866 and #44056).
+            //
+            // To workaround the bug, we trick LLVM into not increasing
+            // the global's alignment by explicitly assigning a section to it
+            // (equivalent to automatically generating a `#[link_section]` attribute).
+            // See the comment in the `GlobalValue::canIncreaseAlignment()` function
+            // of `lib/IR/Globals.cpp` for why this works.
+            //
+            // When the alignment is not increased, the optimized `mem::replace`
+            // will use load-unaligned instructions instead, and thus avoiding the crash.
+            //
+            // We could remove this hack whenever we decide to drop macOS 10.10 support.
+            if self.tcx.sess.target.options.is_like_osx {
+                // The `inspect` method is okay here because we checked relocations, and
+                // because we are doing this access to inspect the final interpreter state
+                // (not as part of the interpreter execution).
+                //
+                // FIXME: This check requires that the (arbitrary) value of undefined bytes
+                // happens to be zero. Instead, we should only check the value of defined bytes
+                // and set all undefined bytes to zero if this allocation is headed for the
+                // BSS.
+                unimplemented!();
+            }
+        }
+
+        // Wasm statics with custom link sections get special treatment as they
+        // go into custom sections of the wasm executable.
+        if self.tcx.sess.opts.target_triple.triple().starts_with("wasm32") {
+            if let Some(_section) = attrs.link_section {
+                unimplemented!();
+            }
+        } else {
+            // TODO(antoyo): set link section.
+        }
+
+        if attrs.flags.contains(CodegenFnAttrFlags::USED) {
+            self.add_used_global(global.to_rvalue());
+        }
+    }
+
+    /// Add a global value to a list to be stored in the `llvm.used` variable, an array of i8*.
+    fn add_used_global(&self, _global: RValue<'gcc>) {
+        // TODO(antoyo)
+    }
+
+    fn add_compiler_used_global(&self, _global: RValue<'gcc>) {
+        // TODO(antoyo)
+    }
+}
+
+impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
+    pub fn static_addr_of_mut(&self, cv: RValue<'gcc>, align: Align, kind: Option<&str>) -> RValue<'gcc> {
+        let global =
+            match kind {
+                Some(kind) if !self.tcx.sess.fewer_names() => {
+                    let name = self.generate_local_symbol_name(kind);
+                    // TODO(antoyo): check if it's okay that TLS is off here.
+                    // TODO(antoyo): check if it's okay that link_section is None here.
+                    // TODO(antoyo): set alignment here as well.
+                    let global = self.define_global(&name[..], self.val_ty(cv), false, None);
+                    // TODO(antoyo): set linkage.
+                    global
+                }
+                _ => {
+                    let typ = self.val_ty(cv).get_aligned(align.bytes());
+                    let global = self.declare_unnamed_global(typ);
+                    global
+                },
+            };
+        // FIXME(antoyo): I think the name coming from generate_local_symbol_name() above cannot be used
+        // globally.
+        global.global_set_initializer_value(cv);
+        // TODO(antoyo): set unnamed address.
+        global.get_address(None)
+    }
+
+    pub fn get_static(&self, def_id: DefId) -> LValue<'gcc> {
+        let instance = Instance::mono(self.tcx, def_id);
+        let fn_attrs = self.tcx.codegen_fn_attrs(def_id);
+        if let Some(&global) = self.instances.borrow().get(&instance) {
+            return global;
+        }
+
+        let defined_in_current_codegen_unit =
+            self.codegen_unit.items().contains_key(&MonoItem::Static(def_id));
+        assert!(
+            !defined_in_current_codegen_unit,
+            "consts::get_static() should always hit the cache for \
+                 statics defined in the same CGU, but did not for `{:?}`",
+            def_id
+        );
+
+        let ty = instance.ty(self.tcx, ty::ParamEnv::reveal_all());
+        let sym = self.tcx.symbol_name(instance).name;
+
+        let global =
+            if let Some(def_id) = def_id.as_local() {
+                let id = self.tcx.hir().local_def_id_to_hir_id(def_id);
+                let llty = self.layout_of(ty).gcc_type(self, true);
+                // FIXME: refactor this to work without accessing the HIR
+                let global = match self.tcx.hir().get(id) {
+                    Node::Item(&hir::Item { span, kind: hir::ItemKind::Static(..), .. }) => {
+                        if let Some(global) = self.get_declared_value(&sym) {
+                            if self.val_ty(global) != self.type_ptr_to(llty) {
+                                span_bug!(span, "Conflicting types for static");
+                            }
+                        }
+
+                        let is_tls = fn_attrs.flags.contains(CodegenFnAttrFlags::THREAD_LOCAL);
+                        let global = self.declare_global(&sym, llty, is_tls, fn_attrs.link_section);
+
+                        if !self.tcx.is_reachable_non_generic(def_id) {
+                            // TODO(antoyo): set visibility.
+                        }
+
+                        global
+                    }
+
+                    Node::ForeignItem(&hir::ForeignItem {
+                        span,
+                        kind: hir::ForeignItemKind::Static(..),
+                        ..
+                    }) => {
+                        let fn_attrs = self.tcx.codegen_fn_attrs(def_id);
+                        check_and_apply_linkage(&self, &fn_attrs, ty, sym, span)
+                    }
+
+                    item => bug!("get_static: expected static, found {:?}", item),
+                };
+
+                global
+            }
+            else {
+                // FIXME(nagisa): perhaps the map of externs could be offloaded to llvm somehow?
+                //debug!("get_static: sym={} item_attr={:?}", sym, self.tcx.item_attrs(def_id));
+
+                let attrs = self.tcx.codegen_fn_attrs(def_id);
+                let span = self.tcx.def_span(def_id);
+                let global = check_and_apply_linkage(&self, &attrs, ty, sym, span);
+
+                let needs_dll_storage_attr = false; // TODO(antoyo)
+
+                // If this assertion triggers, there's something wrong with commandline
+                // argument validation.
+                debug_assert!(
+                    !(self.tcx.sess.opts.cg.linker_plugin_lto.enabled()
+                        && self.tcx.sess.target.options.is_like_msvc
+                        && self.tcx.sess.opts.cg.prefer_dynamic)
+                );
+
+                if needs_dll_storage_attr {
+                    // This item is external but not foreign, i.e., it originates from an external Rust
+                    // crate. Since we don't know whether this crate will be linked dynamically or
+                    // statically in the final application, we always mark such symbols as 'dllimport'.
+                    // If final linkage happens to be static, we rely on compiler-emitted __imp_ stubs
+                    // to make things work.
+                    //
+                    // However, in some scenarios we defer emission of statics to downstream
+                    // crates, so there are cases where a static with an upstream DefId
+                    // is actually present in the current crate. We can find out via the
+                    // is_codegened_item query.
+                    if !self.tcx.is_codegened_item(def_id) {
+                        unimplemented!();
+                    }
+                }
+                global
+            };
+
+        // TODO(antoyo): set dll storage class.
+
+        self.instances.borrow_mut().insert(instance, global);
+        global
+    }
+}
+
+pub fn const_alloc_to_gcc<'gcc, 'tcx>(cx: &CodegenCx<'gcc, 'tcx>, alloc: &Allocation) -> RValue<'gcc> {
+    let mut llvals = Vec::with_capacity(alloc.relocations().len() + 1);
+    let dl = cx.data_layout();
+    let pointer_size = dl.pointer_size.bytes() as usize;
+
+    let mut next_offset = 0;
+    for &(offset, alloc_id) in alloc.relocations().iter() {
+        let offset = offset.bytes();
+        assert_eq!(offset as usize as u64, offset);
+        let offset = offset as usize;
+        if offset > next_offset {
+            // This `inspect` is okay since we have checked that it is not within a relocation, it
+            // is within the bounds of the allocation, and it doesn't affect interpreter execution
+            // (we inspect the result after interpreter execution). Any undef byte is replaced with
+            // some arbitrary byte value.
+            //
+            // FIXME: relay undef bytes to codegen as undef const bytes
+            let bytes = alloc.inspect_with_uninit_and_ptr_outside_interpreter(next_offset..offset);
+            llvals.push(cx.const_bytes(bytes));
+        }
+        let ptr_offset =
+            read_target_uint( dl.endian,
+                // This `inspect` is okay since it is within the bounds of the allocation, it doesn't
+                // affect interpreter execution (we inspect the result after interpreter execution),
+                // and we properly interpret the relocation as a relocation pointer offset.
+                alloc.inspect_with_uninit_and_ptr_outside_interpreter(offset..(offset + pointer_size)),
+            )
+            .expect("const_alloc_to_llvm: could not read relocation pointer")
+            as u64;
+        llvals.push(cx.scalar_to_backend(
+            InterpScalar::from_pointer(
+                interpret::Pointer::new(alloc_id, Size::from_bytes(ptr_offset)),
+                &cx.tcx,
+            ),
+            abi::Scalar { value: Primitive::Pointer, valid_range: WrappingRange { start: 0, end: !0 } },
+            cx.type_i8p(),
+        ));
+        next_offset = offset + pointer_size;
+    }
+    if alloc.len() >= next_offset {
+        let range = next_offset..alloc.len();
+        // This `inspect` is okay since we have check that it is after all relocations, it is
+        // within the bounds of the allocation, and it doesn't affect interpreter execution (we
+        // inspect the result after interpreter execution). Any undef byte is replaced with some
+        // arbitrary byte value.
+        //
+        // FIXME: relay undef bytes to codegen as undef const bytes
+        let bytes = alloc.inspect_with_uninit_and_ptr_outside_interpreter(range);
+        llvals.push(cx.const_bytes(bytes));
+    }
+
+    cx.const_struct(&llvals, true)
+}
+
+pub fn codegen_static_initializer<'gcc, 'tcx>(cx: &CodegenCx<'gcc, 'tcx>, def_id: DefId) -> Result<(RValue<'gcc>, &'tcx Allocation), ErrorHandled> {
+    let alloc = cx.tcx.eval_static_initializer(def_id)?;
+    Ok((const_alloc_to_gcc(cx, alloc), alloc))
+}
+
+fn check_and_apply_linkage<'gcc, 'tcx>(cx: &CodegenCx<'gcc, 'tcx>, attrs: &CodegenFnAttrs, ty: Ty<'tcx>, sym: &str, span: Span) -> LValue<'gcc> {
+    let is_tls = attrs.flags.contains(CodegenFnAttrFlags::THREAD_LOCAL);
+    let llty = cx.layout_of(ty).gcc_type(cx, true);
+    if let Some(linkage) = attrs.linkage {
+        // If this is a static with a linkage specified, then we need to handle
+        // it a little specially. The typesystem prevents things like &T and
+        // extern "C" fn() from being non-null, so we can't just declare a
+        // static and call it a day. Some linkages (like weak) will make it such
+        // that the static actually has a null value.
+        let llty2 =
+            if let ty::RawPtr(ref mt) = ty.kind() {
+                cx.layout_of(mt.ty).gcc_type(cx, true)
+            }
+            else {
+                cx.sess().span_fatal(
+                    span,
+                    "must have type `*const T` or `*mut T` due to `#[linkage]` attribute",
+                )
+            };
+        // Declare a symbol `foo` with the desired linkage.
+        let global1 = cx.declare_global_with_linkage(&sym, llty2, base::global_linkage_to_gcc(linkage));
+
+        // Declare an internal global `extern_with_linkage_foo` which
+        // is initialized with the address of `foo`.  If `foo` is
+        // discarded during linking (for example, if `foo` has weak
+        // linkage and there are no definitions), then
+        // `extern_with_linkage_foo` will instead be initialized to
+        // zero.
+        let mut real_name = "_rust_extern_with_linkage_".to_string();
+        real_name.push_str(&sym);
+        let global2 = cx.define_global(&real_name, llty, is_tls, attrs.link_section);
+        // TODO(antoyo): set linkage.
+        global2.global_set_initializer_value(global1.get_address(None));
+        // TODO(antoyo): use global_set_initializer() when it will work.
+        global2
+    }
+    else {
+        // Generate an external declaration.
+        // FIXME(nagisa): investigate whether it can be changed into define_global
+
+        // Thread-local statics in some other crate need to *always* be linked
+        // against in a thread-local fashion, so we need to be sure to apply the
+        // thread-local attribute locally if it was present remotely. If we
+        // don't do this then linker errors can be generated where the linker
+        // complains that one object files has a thread local version of the
+        // symbol and another one doesn't.
+        cx.declare_global(&sym, llty, is_tls, attrs.link_section)
+    }
+}
diff --git a/compiler/rustc_codegen_gcc/src/context.rs b/compiler/rustc_codegen_gcc/src/context.rs
new file mode 100644
index 00000000000..7677ade7314
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/context.rs
@@ -0,0 +1,475 @@
+use std::cell::{Cell, RefCell};
+
+use gccjit::{
+    Block,
+    Context,
+    CType,
+    Function,
+    FunctionType,
+    LValue,
+    RValue,
+    Struct,
+    Type,
+};
+use rustc_codegen_ssa::base::wants_msvc_seh;
+use rustc_codegen_ssa::traits::{
+    BackendTypes,
+    MiscMethods,
+};
+use rustc_data_structures::base_n;
+use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_middle::span_bug;
+use rustc_middle::mir::mono::CodegenUnit;
+use rustc_middle::ty::{self, Instance, ParamEnv, PolyExistentialTraitRef, Ty, TyCtxt};
+use rustc_middle::ty::layout::{FnAbiError, FnAbiOfHelpers, FnAbiRequest, HasParamEnv, HasTyCtxt, LayoutError, TyAndLayout, LayoutOfHelpers};
+use rustc_session::Session;
+use rustc_span::{Span, Symbol};
+use rustc_target::abi::{call::FnAbi, HasDataLayout, PointeeInfo, Size, TargetDataLayout, VariantIdx};
+use rustc_target::spec::{HasTargetSpec, Target, TlsModel};
+
+use crate::callee::get_fn;
+use crate::declare::mangle_name;
+
+#[derive(Clone)]
+pub struct FuncSig<'gcc> {
+    pub params: Vec<Type<'gcc>>,
+    pub return_type: Type<'gcc>,
+}
+
+pub struct CodegenCx<'gcc, 'tcx> {
+    pub check_overflow: bool,
+    pub codegen_unit: &'tcx CodegenUnit<'tcx>,
+    pub context: &'gcc Context<'gcc>,
+
+    // TODO(antoyo): First set it to a dummy block to avoid using Option?
+    pub current_block: RefCell<Option<Block<'gcc>>>,
+    pub current_func: RefCell<Option<Function<'gcc>>>,
+    pub normal_function_addresses: RefCell<FxHashSet<RValue<'gcc>>>,
+
+    pub functions: RefCell<FxHashMap<String, Function<'gcc>>>,
+
+    pub tls_model: gccjit::TlsModel,
+
+    pub bool_type: Type<'gcc>,
+    pub i8_type: Type<'gcc>,
+    pub i16_type: Type<'gcc>,
+    pub i32_type: Type<'gcc>,
+    pub i64_type: Type<'gcc>,
+    pub i128_type: Type<'gcc>,
+    pub isize_type: Type<'gcc>,
+
+    pub u8_type: Type<'gcc>,
+    pub u16_type: Type<'gcc>,
+    pub u32_type: Type<'gcc>,
+    pub u64_type: Type<'gcc>,
+    pub u128_type: Type<'gcc>,
+    pub usize_type: Type<'gcc>,
+
+    pub int_type: Type<'gcc>,
+    pub uint_type: Type<'gcc>,
+    pub long_type: Type<'gcc>,
+    pub ulong_type: Type<'gcc>,
+    pub ulonglong_type: Type<'gcc>,
+    pub sizet_type: Type<'gcc>,
+
+    pub float_type: Type<'gcc>,
+    pub double_type: Type<'gcc>,
+
+    pub linkage: Cell<FunctionType>,
+    pub scalar_types: RefCell<FxHashMap<Ty<'tcx>, Type<'gcc>>>,
+    pub types: RefCell<FxHashMap<(Ty<'tcx>, Option<VariantIdx>), Type<'gcc>>>,
+    pub tcx: TyCtxt<'tcx>,
+
+    pub struct_types: RefCell<FxHashMap<Vec<Type<'gcc>>, Type<'gcc>>>,
+
+    pub types_with_fields_to_set: RefCell<FxHashMap<Type<'gcc>, (Struct<'gcc>, TyAndLayout<'tcx>)>>,
+
+    /// Cache instances of monomorphic and polymorphic items
+    pub instances: RefCell<FxHashMap<Instance<'tcx>, LValue<'gcc>>>,
+    /// Cache function instances of monomorphic and polymorphic items
+    pub function_instances: RefCell<FxHashMap<Instance<'tcx>, RValue<'gcc>>>,
+    /// Cache generated vtables
+    pub vtables: RefCell<FxHashMap<(Ty<'tcx>, Option<ty::PolyExistentialTraitRef<'tcx>>), RValue<'gcc>>>,
+
+    /// Cache of emitted const globals (value -> global)
+    pub const_globals: RefCell<FxHashMap<RValue<'gcc>, RValue<'gcc>>>,
+
+    /// Cache of constant strings,
+    pub const_cstr_cache: RefCell<FxHashMap<Symbol, LValue<'gcc>>>,
+
+    /// Cache of globals.
+    pub globals: RefCell<FxHashMap<String, RValue<'gcc>>>,
+
+    /// A counter that is used for generating local symbol names
+    local_gen_sym_counter: Cell<usize>,
+    pub global_gen_sym_counter: Cell<usize>,
+
+    eh_personality: Cell<Option<RValue<'gcc>>>,
+
+    pub pointee_infos: RefCell<FxHashMap<(Ty<'tcx>, Size), Option<PointeeInfo>>>,
+
+    /// NOTE: a hack is used because the rustc API is not suitable to libgccjit and as such,
+    /// `const_undef()` returns struct as pointer so that they can later be assigned a value.
+    /// As such, this set remembers which of these pointers were returned by this function so that
+    /// they can be deferenced later.
+    /// FIXME(antoyo): fix the rustc API to avoid having this hack.
+    pub structs_as_pointer: RefCell<FxHashSet<RValue<'gcc>>>,
+}
+
+impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
+    pub fn new(context: &'gcc Context<'gcc>, codegen_unit: &'tcx CodegenUnit<'tcx>, tcx: TyCtxt<'tcx>) -> Self {
+        let check_overflow = tcx.sess.overflow_checks();
+        // TODO(antoyo): fix this mess. libgccjit seems to return random type when using new_int_type().
+        let isize_type = context.new_c_type(CType::LongLong);
+        let usize_type = context.new_c_type(CType::ULongLong);
+        let bool_type = context.new_type::<bool>();
+        let i8_type = context.new_type::<i8>();
+        let i16_type = context.new_type::<i16>();
+        let i32_type = context.new_type::<i32>();
+        let i64_type = context.new_c_type(CType::LongLong);
+        let i128_type = context.new_c_type(CType::Int128t).get_aligned(8); // TODO(antoyo): should the alignment be hard-coded?
+        let u8_type = context.new_type::<u8>();
+        let u16_type = context.new_type::<u16>();
+        let u32_type = context.new_type::<u32>();
+        let u64_type = context.new_c_type(CType::ULongLong);
+        let u128_type = context.new_c_type(CType::UInt128t).get_aligned(8); // TODO(antoyo): should the alignment be hard-coded?
+
+        let tls_model = to_gcc_tls_mode(tcx.sess.tls_model());
+
+        let float_type = context.new_type::<f32>();
+        let double_type = context.new_type::<f64>();
+
+        let int_type = context.new_c_type(CType::Int);
+        let uint_type = context.new_c_type(CType::UInt);
+        let long_type = context.new_c_type(CType::Long);
+        let ulong_type = context.new_c_type(CType::ULong);
+        let ulonglong_type = context.new_c_type(CType::ULongLong);
+        let sizet_type = context.new_c_type(CType::SizeT);
+
+        assert_eq!(isize_type, i64_type);
+        assert_eq!(usize_type, u64_type);
+
+        let mut functions = FxHashMap::default();
+        let builtins = [
+            "__builtin_unreachable", "abort", "__builtin_expect", "__builtin_add_overflow", "__builtin_mul_overflow",
+            "__builtin_saddll_overflow", /*"__builtin_sadd_overflow",*/ "__builtin_smulll_overflow", /*"__builtin_smul_overflow",*/
+            "__builtin_ssubll_overflow", /*"__builtin_ssub_overflow",*/ "__builtin_sub_overflow", "__builtin_uaddll_overflow",
+            "__builtin_uadd_overflow", "__builtin_umulll_overflow", "__builtin_umul_overflow", "__builtin_usubll_overflow",
+            "__builtin_usub_overflow", "sqrtf", "sqrt", "__builtin_powif", "__builtin_powi", "sinf", "sin", "cosf", "cos",
+            "powf", "pow", "expf", "exp", "exp2f", "exp2", "logf", "log", "log10f", "log10", "log2f", "log2", "fmaf",
+            "fma", "fabsf", "fabs", "fminf", "fmin", "fmaxf", "fmax", "copysignf", "copysign", "floorf", "floor", "ceilf",
+            "ceil", "truncf", "trunc", "rintf", "rint", "nearbyintf", "nearbyint", "roundf", "round",
+            "__builtin_expect_with_probability",
+        ];
+
+        for builtin in builtins.iter() {
+            functions.insert(builtin.to_string(), context.get_builtin_function(builtin));
+        }
+
+        Self {
+            check_overflow,
+            codegen_unit,
+            context,
+            current_block: RefCell::new(None),
+            current_func: RefCell::new(None),
+            normal_function_addresses: Default::default(),
+            functions: RefCell::new(functions),
+
+            tls_model,
+
+            bool_type,
+            i8_type,
+            i16_type,
+            i32_type,
+            i64_type,
+            i128_type,
+            isize_type,
+            usize_type,
+            u8_type,
+            u16_type,
+            u32_type,
+            u64_type,
+            u128_type,
+            int_type,
+            uint_type,
+            long_type,
+            ulong_type,
+            ulonglong_type,
+            sizet_type,
+
+            float_type,
+            double_type,
+
+            linkage: Cell::new(FunctionType::Internal),
+            instances: Default::default(),
+            function_instances: Default::default(),
+            vtables: Default::default(),
+            const_globals: Default::default(),
+            const_cstr_cache: Default::default(),
+            globals: Default::default(),
+            scalar_types: Default::default(),
+            types: Default::default(),
+            tcx,
+            struct_types: Default::default(),
+            types_with_fields_to_set: Default::default(),
+            local_gen_sym_counter: Cell::new(0),
+            global_gen_sym_counter: Cell::new(0),
+            eh_personality: Cell::new(None),
+            pointee_infos: Default::default(),
+            structs_as_pointer: Default::default(),
+        }
+    }
+
+    pub fn rvalue_as_function(&self, value: RValue<'gcc>) -> Function<'gcc> {
+        let function: Function<'gcc> = unsafe { std::mem::transmute(value) };
+        debug_assert!(self.functions.borrow().values().find(|value| **value == function).is_some(),
+            "{:?} ({:?}) is not a function", value, value.get_type());
+        function
+    }
+
+    pub fn sess(&self) -> &Session {
+        &self.tcx.sess
+    }
+}
+
+impl<'gcc, 'tcx> BackendTypes for CodegenCx<'gcc, 'tcx> {
+    type Value = RValue<'gcc>;
+    type Function = RValue<'gcc>;
+
+    type BasicBlock = Block<'gcc>;
+    type Type = Type<'gcc>;
+    type Funclet = (); // TODO(antoyo)
+
+    type DIScope = (); // TODO(antoyo)
+    type DILocation = (); // TODO(antoyo)
+    type DIVariable = (); // TODO(antoyo)
+}
+
+impl<'gcc, 'tcx> MiscMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
+    fn vtables(&self) -> &RefCell<FxHashMap<(Ty<'tcx>, Option<PolyExistentialTraitRef<'tcx>>), RValue<'gcc>>> {
+        &self.vtables
+    }
+
+    fn get_fn(&self, instance: Instance<'tcx>) -> RValue<'gcc> {
+        let func = get_fn(self, instance);
+        *self.current_func.borrow_mut() = Some(self.rvalue_as_function(func));
+        func
+    }
+
+    fn get_fn_addr(&self, instance: Instance<'tcx>) -> RValue<'gcc> {
+        let func = get_fn(self, instance);
+        let func = self.rvalue_as_function(func);
+        let ptr = func.get_address(None);
+
+        // TODO(antoyo): don't do this twice: i.e. in declare_fn and here.
+        // FIXME(antoyo): the rustc API seems to call get_fn_addr() when not needed (e.g. for FFI).
+
+        self.normal_function_addresses.borrow_mut().insert(ptr);
+
+        ptr
+    }
+
+    fn eh_personality(&self) -> RValue<'gcc> {
+        // The exception handling personality function.
+        //
+        // If our compilation unit has the `eh_personality` lang item somewhere
+        // within it, then we just need to codegen that. Otherwise, we're
+        // building an rlib which will depend on some upstream implementation of
+        // this function, so we just codegen a generic reference to it. We don't
+        // specify any of the types for the function, we just make it a symbol
+        // that LLVM can later use.
+        //
+        // Note that MSVC is a little special here in that we don't use the
+        // `eh_personality` lang item at all. Currently LLVM has support for
+        // both Dwarf and SEH unwind mechanisms for MSVC targets and uses the
+        // *name of the personality function* to decide what kind of unwind side
+        // tables/landing pads to emit. It looks like Dwarf is used by default,
+        // injecting a dependency on the `_Unwind_Resume` symbol for resuming
+        // an "exception", but for MSVC we want to force SEH. This means that we
+        // can't actually have the personality function be our standard
+        // `rust_eh_personality` function, but rather we wired it up to the
+        // CRT's custom personality function, which forces LLVM to consider
+        // landing pads as "landing pads for SEH".
+        if let Some(llpersonality) = self.eh_personality.get() {
+            return llpersonality;
+        }
+        let tcx = self.tcx;
+        let llfn = match tcx.lang_items().eh_personality() {
+            Some(def_id) if !wants_msvc_seh(self.sess()) => self.get_fn_addr(
+                ty::Instance::resolve(
+                    tcx,
+                    ty::ParamEnv::reveal_all(),
+                    def_id,
+                    tcx.intern_substs(&[]),
+                )
+                .unwrap().unwrap(),
+            ),
+            _ => {
+                let _name = if wants_msvc_seh(self.sess()) {
+                    "__CxxFrameHandler3"
+                } else {
+                    "rust_eh_personality"
+                };
+                //let func = self.declare_func(name, self.type_i32(), &[], true);
+                // FIXME(antoyo): this hack should not be needed. That will probably be removed when
+                // unwinding support is added.
+                self.context.new_rvalue_from_int(self.int_type, 0)
+            }
+        };
+        // TODO(antoyo): apply target cpu attributes.
+        self.eh_personality.set(Some(llfn));
+        llfn
+    }
+
+    fn sess(&self) -> &Session {
+        &self.tcx.sess
+    }
+
+    fn check_overflow(&self) -> bool {
+        self.check_overflow
+    }
+
+    fn codegen_unit(&self) -> &'tcx CodegenUnit<'tcx> {
+        self.codegen_unit
+    }
+
+    fn used_statics(&self) -> &RefCell<Vec<RValue<'gcc>>> {
+        unimplemented!();
+    }
+
+    fn set_frame_pointer_type(&self, _llfn: RValue<'gcc>) {
+        // TODO(antoyo)
+    }
+
+    fn apply_target_cpu_attr(&self, _llfn: RValue<'gcc>) {
+        // TODO(antoyo)
+    }
+
+    fn create_used_variable(&self) {
+        unimplemented!();
+    }
+
+    fn declare_c_main(&self, fn_type: Self::Type) -> Option<Self::Function> {
+        if self.get_declared_value("main").is_none() {
+            Some(self.declare_cfn("main", fn_type))
+        }
+        else {
+            // If the symbol already exists, it is an error: for example, the user wrote
+            // #[no_mangle] extern "C" fn main(..) {..}
+            // instead of #[start]
+            None
+        }
+    }
+
+    fn compiler_used_statics(&self) -> &RefCell<Vec<RValue<'gcc>>> {
+        unimplemented!()
+    }
+
+    fn create_compiler_used_variable(&self) {
+        unimplemented!()
+    }
+}
+
+impl<'gcc, 'tcx> HasTyCtxt<'tcx> for CodegenCx<'gcc, 'tcx> {
+    fn tcx(&self) -> TyCtxt<'tcx> {
+        self.tcx
+    }
+}
+
+impl<'gcc, 'tcx> HasDataLayout for CodegenCx<'gcc, 'tcx> {
+    fn data_layout(&self) -> &TargetDataLayout {
+        &self.tcx.data_layout
+    }
+}
+
+impl<'gcc, 'tcx> HasTargetSpec for CodegenCx<'gcc, 'tcx> {
+    fn target_spec(&self) -> &Target {
+        &self.tcx.sess.target
+    }
+}
+
+impl<'gcc, 'tcx> LayoutOfHelpers<'tcx> for CodegenCx<'gcc, 'tcx> {
+    type LayoutOfResult = TyAndLayout<'tcx>;
+
+    #[inline]
+    fn handle_layout_err(&self, err: LayoutError<'tcx>, span: Span, ty: Ty<'tcx>) -> ! {
+        if let LayoutError::SizeOverflow(_) = err {
+            self.sess().span_fatal(span, &err.to_string())
+        } else {
+            span_bug!(span, "failed to get layout for `{}`: {}", ty, err)
+        }
+    }
+}
+
+impl<'gcc, 'tcx> FnAbiOfHelpers<'tcx> for CodegenCx<'gcc, 'tcx> {
+    type FnAbiOfResult = &'tcx FnAbi<'tcx, Ty<'tcx>>;
+
+    #[inline]
+    fn handle_fn_abi_err(
+        &self,
+        err: FnAbiError<'tcx>,
+        span: Span,
+        fn_abi_request: FnAbiRequest<'tcx>,
+    ) -> ! {
+        if let FnAbiError::Layout(LayoutError::SizeOverflow(_)) = err {
+            self.sess().span_fatal(span, &err.to_string())
+        } else {
+            match fn_abi_request {
+                FnAbiRequest::OfFnPtr { sig, extra_args } => {
+                    span_bug!(
+                        span,
+                        "`fn_abi_of_fn_ptr({}, {:?})` failed: {}",
+                        sig,
+                        extra_args,
+                        err
+                    );
+                }
+                FnAbiRequest::OfInstance { instance, extra_args } => {
+                    span_bug!(
+                        span,
+                        "`fn_abi_of_instance({}, {:?})` failed: {}",
+                        instance,
+                        extra_args,
+                        err
+                    );
+                }
+            }
+        }
+    }
+}
+
+impl<'tcx, 'gcc> HasParamEnv<'tcx> for CodegenCx<'gcc, 'tcx> {
+    fn param_env(&self) -> ParamEnv<'tcx> {
+        ParamEnv::reveal_all()
+    }
+}
+
+impl<'b, 'tcx> CodegenCx<'b, 'tcx> {
+    /// Generates a new symbol name with the given prefix. This symbol name must
+    /// only be used for definitions with `internal` or `private` linkage.
+    pub fn generate_local_symbol_name(&self, prefix: &str) -> String {
+        let idx = self.local_gen_sym_counter.get();
+        self.local_gen_sym_counter.set(idx + 1);
+        // Include a '.' character, so there can be no accidental conflicts with
+        // user defined names
+        let mut name = String::with_capacity(prefix.len() + 6);
+        name.push_str(prefix);
+        name.push_str(".");
+        base_n::push_str(idx as u128, base_n::ALPHANUMERIC_ONLY, &mut name);
+        name
+    }
+}
+
+pub fn unit_name<'tcx>(codegen_unit: &CodegenUnit<'tcx>) -> String {
+    let name = &codegen_unit.name().to_string();
+    mangle_name(&name.replace('-', "_"))
+}
+
+fn to_gcc_tls_mode(tls_model: TlsModel) -> gccjit::TlsModel {
+    match tls_model {
+        TlsModel::GeneralDynamic => gccjit::TlsModel::GlobalDynamic,
+        TlsModel::LocalDynamic => gccjit::TlsModel::LocalDynamic,
+        TlsModel::InitialExec => gccjit::TlsModel::InitialExec,
+        TlsModel::LocalExec => gccjit::TlsModel::LocalExec,
+    }
+}
diff --git a/compiler/rustc_codegen_gcc/src/coverageinfo.rs b/compiler/rustc_codegen_gcc/src/coverageinfo.rs
new file mode 100644
index 00000000000..872fc2472e2
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/coverageinfo.rs
@@ -0,0 +1,69 @@
+use gccjit::RValue;
+use rustc_codegen_ssa::traits::{CoverageInfoBuilderMethods, CoverageInfoMethods};
+use rustc_hir::def_id::DefId;
+use rustc_middle::mir::coverage::{
+    CodeRegion,
+    CounterValueReference,
+    ExpressionOperandId,
+    InjectedExpressionId,
+    Op,
+};
+use rustc_middle::ty::Instance;
+
+use crate::builder::Builder;
+use crate::context::CodegenCx;
+
+impl<'a, 'gcc, 'tcx> CoverageInfoBuilderMethods<'tcx> for Builder<'a, 'gcc, 'tcx> {
+    fn set_function_source_hash(
+        &mut self,
+        _instance: Instance<'tcx>,
+        _function_source_hash: u64,
+    ) -> bool {
+        unimplemented!();
+    }
+
+    fn add_coverage_counter(&mut self, _instance: Instance<'tcx>, _id: CounterValueReference, _region: CodeRegion) -> bool {
+        // TODO(antoyo)
+        false
+    }
+
+    fn add_coverage_counter_expression(&mut self, _instance: Instance<'tcx>, _id: InjectedExpressionId, _lhs: ExpressionOperandId, _op: Op, _rhs: ExpressionOperandId, _region: Option<CodeRegion>) -> bool {
+        // TODO(antoyo)
+        false
+    }
+
+    fn add_coverage_unreachable(&mut self, _instance: Instance<'tcx>, _region: CodeRegion) -> bool {
+        // TODO(antoyo)
+        false
+    }
+}
+
+impl<'gcc, 'tcx> CoverageInfoMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
+    fn coverageinfo_finalize(&self) {
+        // TODO(antoyo)
+    }
+
+    fn get_pgo_func_name_var(&self, _instance: Instance<'tcx>) -> RValue<'gcc> {
+        unimplemented!();
+    }
+
+    /// Functions with MIR-based coverage are normally codegenned _only_ if
+    /// called. LLVM coverage tools typically expect every function to be
+    /// defined (even if unused), with at least one call to LLVM intrinsic
+    /// `instrprof.increment`.
+    ///
+    /// Codegen a small function that will never be called, with one counter
+    /// that will never be incremented.
+    ///
+    /// For used/called functions, the coverageinfo was already added to the
+    /// `function_coverage_map` (keyed by function `Instance`) during codegen.
+    /// But in this case, since the unused function was _not_ previously
+    /// codegenned, collect the coverage `CodeRegion`s from the MIR and add
+    /// them. The first `CodeRegion` is used to add a single counter, with the
+    /// same counter ID used in the injected `instrprof.increment` intrinsic
+    /// call. Since the function is never called, all other `CodeRegion`s can be
+    /// added as `unreachable_region`s.
+    fn define_unused_fn(&self, _def_id: DefId) {
+        unimplemented!();
+    }
+}
diff --git a/compiler/rustc_codegen_gcc/src/debuginfo.rs b/compiler/rustc_codegen_gcc/src/debuginfo.rs
new file mode 100644
index 00000000000..4d3b4f04bad
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/debuginfo.rs
@@ -0,0 +1,62 @@
+use gccjit::RValue;
+use rustc_codegen_ssa::mir::debuginfo::{FunctionDebugContext, VariableKind};
+use rustc_codegen_ssa::traits::{DebugInfoBuilderMethods, DebugInfoMethods};
+use rustc_middle::mir;
+use rustc_middle::ty::{Instance, Ty};
+use rustc_span::{SourceFile, Span, Symbol};
+use rustc_target::abi::Size;
+use rustc_target::abi::call::FnAbi;
+
+use crate::builder::Builder;
+use crate::context::CodegenCx;
+
+impl<'a, 'gcc, 'tcx> DebugInfoBuilderMethods for Builder<'a, 'gcc, 'tcx> {
+    // FIXME(eddyb) find a common convention for all of the debuginfo-related
+    // names (choose between `dbg`, `debug`, `debuginfo`, `debug_info` etc.).
+    fn dbg_var_addr(&mut self, _dbg_var: Self::DIVariable, _scope_metadata: Self::DIScope, _variable_alloca: Self::Value, _direct_offset: Size, _indirect_offsets: &[Size]) {
+        unimplemented!();
+    }
+
+    fn insert_reference_to_gdb_debug_scripts_section_global(&mut self) {
+        // TODO(antoyo): insert reference to gdb debug scripts section global.
+    }
+
+    fn set_var_name(&mut self, _value: RValue<'gcc>, _name: &str) {
+        unimplemented!();
+    }
+
+    fn set_dbg_loc(&mut self, _dbg_loc: Self::DILocation) {
+        unimplemented!();
+    }
+}
+
+impl<'gcc, 'tcx> DebugInfoMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
+    fn create_vtable_metadata(&self, _ty: Ty<'tcx>, _vtable: Self::Value) {
+        // TODO(antoyo)
+    }
+
+    fn create_function_debug_context(&self, _instance: Instance<'tcx>, _fn_abi: &FnAbi<'tcx, Ty<'tcx>>, _llfn: RValue<'gcc>, _mir: &mir::Body<'tcx>) -> Option<FunctionDebugContext<Self::DIScope, Self::DILocation>> {
+        // TODO(antoyo)
+        None
+    }
+
+    fn extend_scope_to_file(&self, _scope_metadata: Self::DIScope, _file: &SourceFile) -> Self::DIScope {
+        unimplemented!();
+    }
+
+    fn debuginfo_finalize(&self) {
+        // TODO(antoyo)
+    }
+
+    fn create_dbg_var(&self, _variable_name: Symbol, _variable_type: Ty<'tcx>, _scope_metadata: Self::DIScope, _variable_kind: VariableKind, _span: Span) -> Self::DIVariable {
+        unimplemented!();
+    }
+
+    fn dbg_scope_fn(&self, _instance: Instance<'tcx>, _fn_abi: &FnAbi<'tcx, Ty<'tcx>>, _maybe_definition_llfn: Option<RValue<'gcc>>) -> Self::DIScope {
+        unimplemented!();
+    }
+
+    fn dbg_loc(&self, _scope: Self::DIScope, _inlined_at: Option<Self::DILocation>, _span: Span) -> Self::DILocation {
+        unimplemented!();
+    }
+}
diff --git a/compiler/rustc_codegen_gcc/src/declare.rs b/compiler/rustc_codegen_gcc/src/declare.rs
new file mode 100644
index 00000000000..b79a50d1eee
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/declare.rs
@@ -0,0 +1,144 @@
+use gccjit::{Function, FunctionType, GlobalKind, LValue, RValue, Type};
+use rustc_codegen_ssa::traits::BaseTypeMethods;
+use rustc_middle::ty::Ty;
+use rustc_span::Symbol;
+use rustc_target::abi::call::FnAbi;
+
+use crate::abi::FnAbiGccExt;
+use crate::context::{CodegenCx, unit_name};
+use crate::intrinsic::llvm;
+
+impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
+    pub fn get_or_insert_global(&self, name: &str, ty: Type<'gcc>, is_tls: bool, link_section: Option<Symbol>) -> LValue<'gcc> {
+        if self.globals.borrow().contains_key(name) {
+            let typ = self.globals.borrow().get(name).expect("global").get_type();
+            let global = self.context.new_global(None, GlobalKind::Imported, typ, name);
+            if is_tls {
+                global.set_tls_model(self.tls_model);
+            }
+            if let Some(link_section) = link_section {
+                global.set_link_section(&link_section.as_str());
+            }
+            global
+        }
+        else {
+            self.declare_global(name, ty, is_tls, link_section)
+        }
+    }
+
+    pub fn declare_unnamed_global(&self, ty: Type<'gcc>) -> LValue<'gcc> {
+        let index = self.global_gen_sym_counter.get();
+        self.global_gen_sym_counter.set(index + 1);
+        let name = format!("global_{}_{}", index, unit_name(&self.codegen_unit));
+        self.context.new_global(None, GlobalKind::Exported, ty, &name)
+    }
+
+    pub fn declare_global_with_linkage(&self, name: &str, ty: Type<'gcc>, linkage: GlobalKind) -> LValue<'gcc> {
+        let global = self.context.new_global(None, linkage, ty, name);
+        let global_address = global.get_address(None);
+        self.globals.borrow_mut().insert(name.to_string(), global_address);
+        global
+    }
+
+    /*pub fn declare_func(&self, name: &str, return_type: Type<'gcc>, params: &[Type<'gcc>], variadic: bool) -> RValue<'gcc> {
+        self.linkage.set(FunctionType::Exported);
+        let func = declare_raw_fn(self, name, () /*llvm::CCallConv*/, return_type, params, variadic);
+        // FIXME(antoyo): this is a wrong cast. That requires changing the compiler API.
+        unsafe { std::mem::transmute(func) }
+    }*/
+
+    pub fn declare_global(&self, name: &str, ty: Type<'gcc>, is_tls: bool, link_section: Option<Symbol>) -> LValue<'gcc> {
+        let global = self.context.new_global(None, GlobalKind::Exported, ty, name);
+        if is_tls {
+            global.set_tls_model(self.tls_model);
+        }
+        if let Some(link_section) = link_section {
+            global.set_link_section(&link_section.as_str());
+        }
+        let global_address = global.get_address(None);
+        self.globals.borrow_mut().insert(name.to_string(), global_address);
+        global
+    }
+
+    pub fn declare_private_global(&self, name: &str, ty: Type<'gcc>) -> LValue<'gcc> {
+        let global = self.context.new_global(None, GlobalKind::Internal, ty, name);
+        let global_address = global.get_address(None);
+        self.globals.borrow_mut().insert(name.to_string(), global_address);
+        global
+    }
+
+    pub fn declare_cfn(&self, name: &str, _fn_type: Type<'gcc>) -> RValue<'gcc> {
+        // TODO(antoyo): use the fn_type parameter.
+        let const_string = self.context.new_type::<u8>().make_pointer().make_pointer();
+        let return_type = self.type_i32();
+        let variadic = false;
+        self.linkage.set(FunctionType::Exported);
+        let func = declare_raw_fn(self, name, () /*llvm::CCallConv*/, return_type, &[self.type_i32(), const_string], variadic);
+        // NOTE: it is needed to set the current_func here as well, because get_fn() is not called
+        // for the main function.
+        *self.current_func.borrow_mut() = Some(func);
+        // FIXME(antoyo): this is a wrong cast. That requires changing the compiler API.
+        unsafe { std::mem::transmute(func) }
+    }
+
+    pub fn declare_fn(&self, name: &str, fn_abi: &FnAbi<'tcx, Ty<'tcx>>) -> RValue<'gcc> {
+        let (return_type, params, variadic) = fn_abi.gcc_type(self);
+        let func = declare_raw_fn(self, name, () /*fn_abi.llvm_cconv()*/, return_type, &params, variadic);
+        // FIXME(antoyo): this is a wrong cast. That requires changing the compiler API.
+        unsafe { std::mem::transmute(func) }
+    }
+
+    pub fn define_global(&self, name: &str, ty: Type<'gcc>, is_tls: bool, link_section: Option<Symbol>) -> LValue<'gcc> {
+        self.get_or_insert_global(name, ty, is_tls, link_section)
+    }
+
+    pub fn get_declared_value(&self, name: &str) -> Option<RValue<'gcc>> {
+        // TODO(antoyo): use a different field than globals, because this seems to return a function?
+        self.globals.borrow().get(name).cloned()
+    }
+}
+
+/// Declare a function.
+///
+/// If there’s a value with the same name already declared, the function will
+/// update the declaration and return existing Value instead.
+fn declare_raw_fn<'gcc>(cx: &CodegenCx<'gcc, '_>, name: &str, _callconv: () /*llvm::CallConv*/, return_type: Type<'gcc>, param_types: &[Type<'gcc>], variadic: bool) -> Function<'gcc> {
+    if name.starts_with("llvm.") {
+        return llvm::intrinsic(name, cx);
+    }
+    let func =
+        if cx.functions.borrow().contains_key(name) {
+            *cx.functions.borrow().get(name).expect("function")
+        }
+        else {
+            let params: Vec<_> = param_types.into_iter().enumerate()
+                .map(|(index, param)| cx.context.new_parameter(None, *param, &format!("param{}", index))) // TODO(antoyo): set name.
+                .collect();
+            let func = cx.context.new_function(None, cx.linkage.get(), return_type, &params, mangle_name(name), variadic);
+            cx.functions.borrow_mut().insert(name.to_string(), func);
+            func
+        };
+
+    // TODO(antoyo): set function calling convention.
+    // TODO(antoyo): set unnamed address.
+    // TODO(antoyo): set no red zone function attribute.
+    // TODO(antoyo): set attributes for optimisation.
+    // TODO(antoyo): set attributes for non lazy bind.
+
+    // FIXME(antoyo): invalid cast.
+    func
+}
+
+// FIXME(antoyo): this is a hack because libgccjit currently only supports alpha, num and _.
+// Unsupported characters: `$` and `.`.
+pub fn mangle_name(name: &str) -> String {
+    name.replace(|char: char| {
+        if !char.is_alphanumeric() && char != '_' {
+            debug_assert!("$.".contains(char), "Unsupported char in function name: {}", char);
+            true
+        }
+        else {
+            false
+        }
+    }, "_")
+}
diff --git a/compiler/rustc_codegen_gcc/src/intrinsic/llvm.rs b/compiler/rustc_codegen_gcc/src/intrinsic/llvm.rs
new file mode 100644
index 00000000000..b074febc521
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/intrinsic/llvm.rs
@@ -0,0 +1,22 @@
+use gccjit::Function;
+
+use crate::context::CodegenCx;
+
+pub fn intrinsic<'gcc, 'tcx>(name: &str, cx: &CodegenCx<'gcc, 'tcx>) -> Function<'gcc> {
+    let _gcc_name =
+        match name {
+            "llvm.x86.xgetbv" => {
+                let gcc_name = "__builtin_trap";
+                let func = cx.context.get_builtin_function(gcc_name);
+                cx.functions.borrow_mut().insert(gcc_name.to_string(), func);
+                return func;
+            },
+            // NOTE: this doc specifies the equivalent GCC builtins: http://huonw.github.io/llvmint/llvmint/x86/index.html
+            "llvm.x86.sse2.cmp.pd" => "__builtin_ia32_cmppd",
+            "llvm.x86.sse2.movmsk.pd" => "__builtin_ia32_movmskpd",
+            "llvm.x86.sse2.pmovmskb.128" => "__builtin_ia32_pmovmskb128",
+            _ => unimplemented!("unsupported LLVM intrinsic {}", name)
+        };
+
+    unimplemented!();
+}
diff --git a/compiler/rustc_codegen_gcc/src/intrinsic/mod.rs b/compiler/rustc_codegen_gcc/src/intrinsic/mod.rs
new file mode 100644
index 00000000000..375d422cb25
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/intrinsic/mod.rs
@@ -0,0 +1,1067 @@
+pub mod llvm;
+mod simd;
+
+use gccjit::{ComparisonOp, Function, RValue, ToRValue, Type, UnaryOp};
+use rustc_codegen_ssa::MemFlags;
+use rustc_codegen_ssa::base::wants_msvc_seh;
+use rustc_codegen_ssa::common::{IntPredicate, span_invalid_monomorphization_error};
+use rustc_codegen_ssa::mir::operand::{OperandRef, OperandValue};
+use rustc_codegen_ssa::mir::place::PlaceRef;
+use rustc_codegen_ssa::traits::{ArgAbiMethods, BaseTypeMethods, BuilderMethods, ConstMethods, IntrinsicCallMethods};
+use rustc_middle::bug;
+use rustc_middle::ty::{self, Instance, Ty};
+use rustc_middle::ty::layout::LayoutOf;
+use rustc_span::{Span, Symbol, symbol::kw, sym};
+use rustc_target::abi::HasDataLayout;
+use rustc_target::abi::call::{ArgAbi, FnAbi, PassMode};
+use rustc_target::spec::PanicStrategy;
+
+use crate::abi::GccType;
+use crate::builder::Builder;
+use crate::common::{SignType, TypeReflection};
+use crate::context::CodegenCx;
+use crate::type_of::LayoutGccExt;
+use crate::intrinsic::simd::generic_simd_intrinsic;
+
+fn get_simple_intrinsic<'gcc, 'tcx>(cx: &CodegenCx<'gcc, 'tcx>, name: Symbol) -> Option<Function<'gcc>> {
+    let gcc_name = match name {
+        sym::sqrtf32 => "sqrtf",
+        sym::sqrtf64 => "sqrt",
+        sym::powif32 => "__builtin_powif",
+        sym::powif64 => "__builtin_powi",
+        sym::sinf32 => "sinf",
+        sym::sinf64 => "sin",
+        sym::cosf32 => "cosf",
+        sym::cosf64 => "cos",
+        sym::powf32 => "powf",
+        sym::powf64 => "pow",
+        sym::expf32 => "expf",
+        sym::expf64 => "exp",
+        sym::exp2f32 => "exp2f",
+        sym::exp2f64 => "exp2",
+        sym::logf32 => "logf",
+        sym::logf64 => "log",
+        sym::log10f32 => "log10f",
+        sym::log10f64 => "log10",
+        sym::log2f32 => "log2f",
+        sym::log2f64 => "log2",
+        sym::fmaf32 => "fmaf",
+        sym::fmaf64 => "fma",
+        sym::fabsf32 => "fabsf",
+        sym::fabsf64 => "fabs",
+        sym::minnumf32 => "fminf",
+        sym::minnumf64 => "fmin",
+        sym::maxnumf32 => "fmaxf",
+        sym::maxnumf64 => "fmax",
+        sym::copysignf32 => "copysignf",
+        sym::copysignf64 => "copysign",
+        sym::floorf32 => "floorf",
+        sym::floorf64 => "floor",
+        sym::ceilf32 => "ceilf",
+        sym::ceilf64 => "ceil",
+        sym::truncf32 => "truncf",
+        sym::truncf64 => "trunc",
+        sym::rintf32 => "rintf",
+        sym::rintf64 => "rint",
+        sym::nearbyintf32 => "nearbyintf",
+        sym::nearbyintf64 => "nearbyint",
+        sym::roundf32 => "roundf",
+        sym::roundf64 => "round",
+        sym::abort => "abort",
+        _ => return None,
+    };
+    Some(cx.context.get_builtin_function(&gcc_name))
+}
+
+impl<'a, 'gcc, 'tcx> IntrinsicCallMethods<'tcx> for Builder<'a, 'gcc, 'tcx> {
+    fn codegen_intrinsic_call(&mut self, instance: Instance<'tcx>, fn_abi: &FnAbi<'tcx, Ty<'tcx>>, args: &[OperandRef<'tcx, RValue<'gcc>>], llresult: RValue<'gcc>, span: Span) {
+        let tcx = self.tcx;
+        let callee_ty = instance.ty(tcx, ty::ParamEnv::reveal_all());
+
+        let (def_id, substs) = match *callee_ty.kind() {
+            ty::FnDef(def_id, substs) => (def_id, substs),
+            _ => bug!("expected fn item type, found {}", callee_ty),
+        };
+
+        let sig = callee_ty.fn_sig(tcx);
+        let sig = tcx.normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), sig);
+        let arg_tys = sig.inputs();
+        let ret_ty = sig.output();
+        let name = tcx.item_name(def_id);
+        let name_str = &*name.as_str();
+
+        let llret_ty = self.layout_of(ret_ty).gcc_type(self, true);
+        let result = PlaceRef::new_sized(llresult, fn_abi.ret.layout);
+
+        let simple = get_simple_intrinsic(self, name);
+        let llval =
+            match name {
+                _ if simple.is_some() => {
+                    // FIXME(antoyo): remove this cast when the API supports function.
+                    let func = unsafe { std::mem::transmute(simple.expect("simple")) };
+                    self.call(self.type_void(), func, &args.iter().map(|arg| arg.immediate()).collect::<Vec<_>>(), None)
+                },
+                sym::likely => {
+                    self.expect(args[0].immediate(), true)
+                }
+                sym::unlikely => {
+                    self.expect(args[0].immediate(), false)
+                }
+                kw::Try => {
+                    try_intrinsic(
+                        self,
+                        args[0].immediate(),
+                        args[1].immediate(),
+                        args[2].immediate(),
+                        llresult,
+                    );
+                    return;
+                }
+                sym::breakpoint => {
+                    unimplemented!();
+                }
+                sym::va_copy => {
+                    unimplemented!();
+                }
+                sym::va_arg => {
+                    unimplemented!();
+                }
+
+                sym::volatile_load | sym::unaligned_volatile_load => {
+                    let tp_ty = substs.type_at(0);
+                    let mut ptr = args[0].immediate();
+                    if let PassMode::Cast(ty) = fn_abi.ret.mode {
+                        ptr = self.pointercast(ptr, self.type_ptr_to(ty.gcc_type(self)));
+                    }
+                    let load = self.volatile_load(ptr.get_type(), ptr);
+                    // TODO(antoyo): set alignment.
+                    self.to_immediate(load, self.layout_of(tp_ty))
+                }
+                sym::volatile_store => {
+                    let dst = args[0].deref(self.cx());
+                    args[1].val.volatile_store(self, dst);
+                    return;
+                }
+                sym::unaligned_volatile_store => {
+                    let dst = args[0].deref(self.cx());
+                    args[1].val.unaligned_volatile_store(self, dst);
+                    return;
+                }
+                sym::prefetch_read_data
+                    | sym::prefetch_write_data
+                    | sym::prefetch_read_instruction
+                    | sym::prefetch_write_instruction => {
+                        unimplemented!();
+                    }
+                sym::ctlz
+                    | sym::ctlz_nonzero
+                    | sym::cttz
+                    | sym::cttz_nonzero
+                    | sym::ctpop
+                    | sym::bswap
+                    | sym::bitreverse
+                    | sym::rotate_left
+                    | sym::rotate_right
+                    | sym::saturating_add
+                    | sym::saturating_sub => {
+                        let ty = arg_tys[0];
+                        match int_type_width_signed(ty, self) {
+                            Some((width, signed)) => match name {
+                                sym::ctlz | sym::cttz => {
+                                    let func = self.current_func.borrow().expect("func");
+                                    let then_block = func.new_block("then");
+                                    let else_block = func.new_block("else");
+                                    let after_block = func.new_block("after");
+
+                                    let arg = args[0].immediate();
+                                    let result = func.new_local(None, arg.get_type(), "zeros");
+                                    let zero = self.cx.context.new_rvalue_zero(arg.get_type());
+                                    let cond = self.cx.context.new_comparison(None, ComparisonOp::Equals, arg, zero);
+                                    self.llbb().end_with_conditional(None, cond, then_block, else_block);
+
+                                    let zero_result = self.cx.context.new_rvalue_from_long(arg.get_type(), width as i64);
+                                    then_block.add_assignment(None, result, zero_result);
+                                    then_block.end_with_jump(None, after_block);
+
+                                    // NOTE: since jumps were added in a place
+                                    // count_leading_zeroes() does not expect, the current blocks
+                                    // in the state need to be updated.
+                                    *self.current_block.borrow_mut() = Some(else_block);
+                                    self.block = Some(else_block);
+
+                                    let zeros =
+                                        match name {
+                                            sym::ctlz => self.count_leading_zeroes(width, arg),
+                                            sym::cttz => self.count_trailing_zeroes(width, arg),
+                                            _ => unreachable!(),
+                                        };
+                                    else_block.add_assignment(None, result, zeros);
+                                    else_block.end_with_jump(None, after_block);
+
+                                    // NOTE: since jumps were added in a place rustc does not
+                                    // expect, the current blocks in the state need to be updated.
+                                    *self.current_block.borrow_mut() = Some(after_block);
+                                    self.block = Some(after_block);
+
+                                    result.to_rvalue()
+                                }
+                                sym::ctlz_nonzero => {
+                                    self.count_leading_zeroes(width, args[0].immediate())
+                                },
+                                sym::cttz_nonzero => {
+                                    self.count_trailing_zeroes(width, args[0].immediate())
+                                }
+                                sym::ctpop => self.pop_count(args[0].immediate()),
+                                sym::bswap => {
+                                    if width == 8 {
+                                        args[0].immediate() // byte swap a u8/i8 is just a no-op
+                                    }
+                                    else {
+                                        // TODO(antoyo): check if it's faster to use string literals and a
+                                        // match instead of format!.
+                                        let bswap = self.cx.context.get_builtin_function(&format!("__builtin_bswap{}", width));
+                                        let mut arg = args[0].immediate();
+                                        // FIXME(antoyo): this cast should not be necessary. Remove
+                                        // when having proper sized integer types.
+                                        let param_type = bswap.get_param(0).to_rvalue().get_type();
+                                        if param_type != arg.get_type() {
+                                            arg = self.bitcast(arg, param_type);
+                                        }
+                                        self.cx.context.new_call(None, bswap, &[arg])
+                                    }
+                                },
+                                sym::bitreverse => self.bit_reverse(width, args[0].immediate()),
+                                sym::rotate_left | sym::rotate_right => {
+                                    // TODO(antoyo): implement using algorithm from:
+                                    // https://blog.regehr.org/archives/1063
+                                    // for other platforms.
+                                    let is_left = name == sym::rotate_left;
+                                    let val = args[0].immediate();
+                                    let raw_shift = args[1].immediate();
+                                    if is_left {
+                                        self.rotate_left(val, raw_shift, width)
+                                    }
+                                    else {
+                                        self.rotate_right(val, raw_shift, width)
+                                    }
+                                },
+                                sym::saturating_add => {
+                                    self.saturating_add(args[0].immediate(), args[1].immediate(), signed, width)
+                                },
+                                sym::saturating_sub => {
+                                    self.saturating_sub(args[0].immediate(), args[1].immediate(), signed, width)
+                                },
+                                _ => bug!(),
+                            },
+                            None => {
+                                span_invalid_monomorphization_error(
+                                    tcx.sess,
+                                    span,
+                                    &format!(
+                                        "invalid monomorphization of `{}` intrinsic: \
+                                      expected basic integer type, found `{}`",
+                                      name, ty
+                                    ),
+                                );
+                                return;
+                            }
+                        }
+                    }
+
+                sym::raw_eq => {
+                    use rustc_target::abi::Abi::*;
+                    let tp_ty = substs.type_at(0);
+                    let layout = self.layout_of(tp_ty).layout;
+                    let _use_integer_compare = match layout.abi {
+                        Scalar(_) | ScalarPair(_, _) => true,
+                        Uninhabited | Vector { .. } => false,
+                        Aggregate { .. } => {
+                            // For rusty ABIs, small aggregates are actually passed
+                            // as `RegKind::Integer` (see `FnAbi::adjust_for_abi`),
+                            // so we re-use that same threshold here.
+                            layout.size <= self.data_layout().pointer_size * 2
+                        }
+                    };
+
+                    let a = args[0].immediate();
+                    let b = args[1].immediate();
+                    if layout.size.bytes() == 0 {
+                        self.const_bool(true)
+                    }
+                    /*else if use_integer_compare {
+                        let integer_ty = self.type_ix(layout.size.bits()); // FIXME(antoyo): LLVM creates an integer of 96 bits for [i32; 3], but gcc doesn't support this, so it creates an integer of 128 bits.
+                        let ptr_ty = self.type_ptr_to(integer_ty);
+                        let a_ptr = self.bitcast(a, ptr_ty);
+                        let a_val = self.load(integer_ty, a_ptr, layout.align.abi);
+                        let b_ptr = self.bitcast(b, ptr_ty);
+                        let b_val = self.load(integer_ty, b_ptr, layout.align.abi);
+                        self.icmp(IntPredicate::IntEQ, a_val, b_val)
+                    }*/
+                    else {
+                        let void_ptr_type = self.context.new_type::<*const ()>();
+                        let a_ptr = self.bitcast(a, void_ptr_type);
+                        let b_ptr = self.bitcast(b, void_ptr_type);
+                        let n = self.context.new_cast(None, self.const_usize(layout.size.bytes()), self.sizet_type);
+                        let builtin = self.context.get_builtin_function("memcmp");
+                        let cmp = self.context.new_call(None, builtin, &[a_ptr, b_ptr, n]);
+                        self.icmp(IntPredicate::IntEQ, cmp, self.const_i32(0))
+                    }
+                }
+
+                sym::black_box => {
+                    args[0].val.store(self, result);
+
+                    let block = self.llbb();
+                    let extended_asm = block.add_extended_asm(None, "");
+                    extended_asm.add_input_operand(None, "r", result.llval);
+                    extended_asm.add_clobber("memory");
+                    extended_asm.set_volatile_flag(true);
+                    
+                    // We have copied the value to `result` already.
+                    return;
+                }
+
+                _ if name_str.starts_with("simd_") => {
+                    match generic_simd_intrinsic(self, name, callee_ty, args, ret_ty, llret_ty, span) {
+                        Ok(llval) => llval,
+                        Err(()) => return,
+                    }
+                }
+
+                _ => bug!("unknown intrinsic '{}'", name),
+            };
+
+        if !fn_abi.ret.is_ignore() {
+            if let PassMode::Cast(ty) = fn_abi.ret.mode {
+                let ptr_llty = self.type_ptr_to(ty.gcc_type(self));
+                let ptr = self.pointercast(result.llval, ptr_llty);
+                self.store(llval, ptr, result.align);
+            }
+            else {
+                OperandRef::from_immediate_or_packed_pair(self, llval, result.layout)
+                    .val
+                    .store(self, result);
+            }
+        }
+    }
+
+    fn abort(&mut self) {
+        let func = self.context.get_builtin_function("abort");
+        let func: RValue<'gcc> = unsafe { std::mem::transmute(func) };
+        self.call(self.type_void(), func, &[], None);
+    }
+
+    fn assume(&mut self, value: Self::Value) {
+        // TODO(antoyo): switch to asumme when it exists.
+        // Or use something like this:
+        // #define __assume(cond) do { if (!(cond)) __builtin_unreachable(); } while (0)
+        self.expect(value, true);
+    }
+
+    fn expect(&mut self, cond: Self::Value, _expected: bool) -> Self::Value {
+        // TODO(antoyo)
+        cond
+    }
+
+    fn sideeffect(&mut self) {
+        // TODO(antoyo)
+    }
+
+    fn va_start(&mut self, _va_list: RValue<'gcc>) -> RValue<'gcc> {
+        unimplemented!();
+    }
+
+    fn va_end(&mut self, _va_list: RValue<'gcc>) -> RValue<'gcc> {
+        unimplemented!();
+    }
+}
+
+impl<'a, 'gcc, 'tcx> ArgAbiMethods<'tcx> for Builder<'a, 'gcc, 'tcx> {
+    fn store_fn_arg(&mut self, arg_abi: &ArgAbi<'tcx, Ty<'tcx>>, idx: &mut usize, dst: PlaceRef<'tcx, Self::Value>) {
+        arg_abi.store_fn_arg(self, idx, dst)
+    }
+
+    fn store_arg(&mut self, arg_abi: &ArgAbi<'tcx, Ty<'tcx>>, val: RValue<'gcc>, dst: PlaceRef<'tcx, RValue<'gcc>>) {
+        arg_abi.store(self, val, dst)
+    }
+
+    fn arg_memory_ty(&self, arg_abi: &ArgAbi<'tcx, Ty<'tcx>>) -> Type<'gcc> {
+        arg_abi.memory_ty(self)
+    }
+}
+
+pub trait ArgAbiExt<'gcc, 'tcx> {
+    fn memory_ty(&self, cx: &CodegenCx<'gcc, 'tcx>) -> Type<'gcc>;
+    fn store(&self, bx: &mut Builder<'_, 'gcc, 'tcx>, val: RValue<'gcc>, dst: PlaceRef<'tcx, RValue<'gcc>>);
+    fn store_fn_arg(&self, bx: &mut Builder<'_, 'gcc, 'tcx>, idx: &mut usize, dst: PlaceRef<'tcx, RValue<'gcc>>);
+}
+
+impl<'gcc, 'tcx> ArgAbiExt<'gcc, 'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
+    /// Gets the LLVM type for a place of the original Rust type of
+    /// this argument/return, i.e., the result of `type_of::type_of`.
+    fn memory_ty(&self, cx: &CodegenCx<'gcc, 'tcx>) -> Type<'gcc> {
+        self.layout.gcc_type(cx, true)
+    }
+
+    /// Stores a direct/indirect value described by this ArgAbi into a
+    /// place for the original Rust type of this argument/return.
+    /// Can be used for both storing formal arguments into Rust variables
+    /// or results of call/invoke instructions into their destinations.
+    fn store(&self, bx: &mut Builder<'_, 'gcc, 'tcx>, val: RValue<'gcc>, dst: PlaceRef<'tcx, RValue<'gcc>>) {
+        if self.is_ignore() {
+            return;
+        }
+        if self.is_sized_indirect() {
+            OperandValue::Ref(val, None, self.layout.align.abi).store(bx, dst)
+        }
+        else if self.is_unsized_indirect() {
+            bug!("unsized `ArgAbi` must be handled through `store_fn_arg`");
+        }
+        else if let PassMode::Cast(cast) = self.mode {
+            // FIXME(eddyb): Figure out when the simpler Store is safe, clang
+            // uses it for i16 -> {i8, i8}, but not for i24 -> {i8, i8, i8}.
+            let can_store_through_cast_ptr = false;
+            if can_store_through_cast_ptr {
+                let cast_ptr_llty = bx.type_ptr_to(cast.gcc_type(bx));
+                let cast_dst = bx.pointercast(dst.llval, cast_ptr_llty);
+                bx.store(val, cast_dst, self.layout.align.abi);
+            }
+            else {
+                // The actual return type is a struct, but the ABI
+                // adaptation code has cast it into some scalar type.  The
+                // code that follows is the only reliable way I have
+                // found to do a transform like i64 -> {i32,i32}.
+                // Basically we dump the data onto the stack then memcpy it.
+                //
+                // Other approaches I tried:
+                // - Casting rust ret pointer to the foreign type and using Store
+                //   is (a) unsafe if size of foreign type > size of rust type and
+                //   (b) runs afoul of strict aliasing rules, yielding invalid
+                //   assembly under -O (specifically, the store gets removed).
+                // - Truncating foreign type to correct integral type and then
+                //   bitcasting to the struct type yields invalid cast errors.
+
+                // We instead thus allocate some scratch space...
+                let scratch_size = cast.size(bx);
+                let scratch_align = cast.align(bx);
+                let llscratch = bx.alloca(cast.gcc_type(bx), scratch_align);
+                bx.lifetime_start(llscratch, scratch_size);
+
+                // ... where we first store the value...
+                bx.store(val, llscratch, scratch_align);
+
+                // ... and then memcpy it to the intended destination.
+                bx.memcpy(
+                    dst.llval,
+                    self.layout.align.abi,
+                    llscratch,
+                    scratch_align,
+                    bx.const_usize(self.layout.size.bytes()),
+                    MemFlags::empty(),
+                );
+
+                bx.lifetime_end(llscratch, scratch_size);
+            }
+        }
+        else {
+            OperandValue::Immediate(val).store(bx, dst);
+        }
+    }
+
+    fn store_fn_arg<'a>(&self, bx: &mut Builder<'a, 'gcc, 'tcx>, idx: &mut usize, dst: PlaceRef<'tcx, RValue<'gcc>>) {
+        let mut next = || {
+            let val = bx.current_func().get_param(*idx as i32);
+            *idx += 1;
+            val.to_rvalue()
+        };
+        match self.mode {
+            PassMode::Ignore => {}
+            PassMode::Pair(..) => {
+                OperandValue::Pair(next(), next()).store(bx, dst);
+            }
+            PassMode::Indirect { extra_attrs: Some(_), .. } => {
+                OperandValue::Ref(next(), Some(next()), self.layout.align.abi).store(bx, dst);
+            }
+            PassMode::Direct(_) | PassMode::Indirect { extra_attrs: None, .. } | PassMode::Cast(_) => {
+                let next_arg = next();
+                self.store(bx, next_arg.to_rvalue(), dst);
+            }
+        }
+    }
+}
+
+fn int_type_width_signed<'gcc, 'tcx>(ty: Ty<'tcx>, cx: &CodegenCx<'gcc, 'tcx>) -> Option<(u64, bool)> {
+    match ty.kind() {
+        ty::Int(t) => Some((
+            match t {
+                rustc_middle::ty::IntTy::Isize => u64::from(cx.tcx.sess.target.pointer_width),
+                rustc_middle::ty::IntTy::I8 => 8,
+                rustc_middle::ty::IntTy::I16 => 16,
+                rustc_middle::ty::IntTy::I32 => 32,
+                rustc_middle::ty::IntTy::I64 => 64,
+                rustc_middle::ty::IntTy::I128 => 128,
+            },
+            true,
+        )),
+        ty::Uint(t) => Some((
+            match t {
+                rustc_middle::ty::UintTy::Usize => u64::from(cx.tcx.sess.target.pointer_width),
+                rustc_middle::ty::UintTy::U8 => 8,
+                rustc_middle::ty::UintTy::U16 => 16,
+                rustc_middle::ty::UintTy::U32 => 32,
+                rustc_middle::ty::UintTy::U64 => 64,
+                rustc_middle::ty::UintTy::U128 => 128,
+            },
+            false,
+        )),
+        _ => None,
+    }
+}
+
+impl<'a, 'gcc, 'tcx> Builder<'a, 'gcc, 'tcx> {
+    fn bit_reverse(&mut self, width: u64, value: RValue<'gcc>) -> RValue<'gcc> {
+        let result_type = value.get_type();
+        let typ = result_type.to_unsigned(self.cx);
+
+        let value =
+            if result_type.is_signed(self.cx) {
+                self.context.new_bitcast(None, value, typ)
+            }
+            else {
+                value
+            };
+
+        let context = &self.cx.context;
+        let result =
+            match width {
+                8 => {
+                    // First step.
+                    let left = self.and(value, context.new_rvalue_from_int(typ, 0xF0));
+                    let left = self.lshr(left, context.new_rvalue_from_int(typ, 4));
+                    let right = self.and(value, context.new_rvalue_from_int(typ, 0x0F));
+                    let right = self.shl(right, context.new_rvalue_from_int(typ, 4));
+                    let step1 = self.or(left, right);
+
+                    // Second step.
+                    let left = self.and(step1, context.new_rvalue_from_int(typ, 0xCC));
+                    let left = self.lshr(left, context.new_rvalue_from_int(typ, 2));
+                    let right = self.and(step1, context.new_rvalue_from_int(typ, 0x33));
+                    let right = self.shl(right, context.new_rvalue_from_int(typ, 2));
+                    let step2 = self.or(left, right);
+
+                    // Third step.
+                    let left = self.and(step2, context.new_rvalue_from_int(typ, 0xAA));
+                    let left = self.lshr(left, context.new_rvalue_from_int(typ, 1));
+                    let right = self.and(step2, context.new_rvalue_from_int(typ, 0x55));
+                    let right = self.shl(right, context.new_rvalue_from_int(typ, 1));
+                    let step3 = self.or(left, right);
+
+                    step3
+                },
+                16 => {
+                    // First step.
+                    let left = self.and(value, context.new_rvalue_from_int(typ, 0x5555));
+                    let left = self.shl(left, context.new_rvalue_from_int(typ, 1));
+                    let right = self.and(value, context.new_rvalue_from_int(typ, 0xAAAA));
+                    let right = self.lshr(right, context.new_rvalue_from_int(typ, 1));
+                    let step1 = self.or(left, right);
+
+                    // Second step.
+                    let left = self.and(step1, context.new_rvalue_from_int(typ, 0x3333));
+                    let left = self.shl(left, context.new_rvalue_from_int(typ, 2));
+                    let right = self.and(step1, context.new_rvalue_from_int(typ, 0xCCCC));
+                    let right = self.lshr(right, context.new_rvalue_from_int(typ, 2));
+                    let step2 = self.or(left, right);
+
+                    // Third step.
+                    let left = self.and(step2, context.new_rvalue_from_int(typ, 0x0F0F));
+                    let left = self.shl(left, context.new_rvalue_from_int(typ, 4));
+                    let right = self.and(step2, context.new_rvalue_from_int(typ, 0xF0F0));
+                    let right = self.lshr(right, context.new_rvalue_from_int(typ, 4));
+                    let step3 = self.or(left, right);
+
+                    // Fourth step.
+                    let left = self.and(step3, context.new_rvalue_from_int(typ, 0x00FF));
+                    let left = self.shl(left, context.new_rvalue_from_int(typ, 8));
+                    let right = self.and(step3, context.new_rvalue_from_int(typ, 0xFF00));
+                    let right = self.lshr(right, context.new_rvalue_from_int(typ, 8));
+                    let step4 = self.or(left, right);
+
+                    step4
+                },
+                32 => {
+                    // TODO(antoyo): Refactor with other implementations.
+                    // First step.
+                    let left = self.and(value, context.new_rvalue_from_long(typ, 0x55555555));
+                    let left = self.shl(left, context.new_rvalue_from_long(typ, 1));
+                    let right = self.and(value, context.new_rvalue_from_long(typ, 0xAAAAAAAA));
+                    let right = self.lshr(right, context.new_rvalue_from_long(typ, 1));
+                    let step1 = self.or(left, right);
+
+                    // Second step.
+                    let left = self.and(step1, context.new_rvalue_from_long(typ, 0x33333333));
+                    let left = self.shl(left, context.new_rvalue_from_long(typ, 2));
+                    let right = self.and(step1, context.new_rvalue_from_long(typ, 0xCCCCCCCC));
+                    let right = self.lshr(right, context.new_rvalue_from_long(typ, 2));
+                    let step2 = self.or(left, right);
+
+                    // Third step.
+                    let left = self.and(step2, context.new_rvalue_from_long(typ, 0x0F0F0F0F));
+                    let left = self.shl(left, context.new_rvalue_from_long(typ, 4));
+                    let right = self.and(step2, context.new_rvalue_from_long(typ, 0xF0F0F0F0));
+                    let right = self.lshr(right, context.new_rvalue_from_long(typ, 4));
+                    let step3 = self.or(left, right);
+
+                    // Fourth step.
+                    let left = self.and(step3, context.new_rvalue_from_long(typ, 0x00FF00FF));
+                    let left = self.shl(left, context.new_rvalue_from_long(typ, 8));
+                    let right = self.and(step3, context.new_rvalue_from_long(typ, 0xFF00FF00));
+                    let right = self.lshr(right, context.new_rvalue_from_long(typ, 8));
+                    let step4 = self.or(left, right);
+
+                    // Fifth step.
+                    let left = self.and(step4, context.new_rvalue_from_long(typ, 0x0000FFFF));
+                    let left = self.shl(left, context.new_rvalue_from_long(typ, 16));
+                    let right = self.and(step4, context.new_rvalue_from_long(typ, 0xFFFF0000));
+                    let right = self.lshr(right, context.new_rvalue_from_long(typ, 16));
+                    let step5 = self.or(left, right);
+
+                    step5
+                },
+                64 => {
+                    // First step.
+                    let left = self.shl(value, context.new_rvalue_from_long(typ, 32));
+                    let right = self.lshr(value, context.new_rvalue_from_long(typ, 32));
+                    let step1 = self.or(left, right);
+
+                    // Second step.
+                    let left = self.and(step1, context.new_rvalue_from_long(typ, 0x0001FFFF0001FFFF));
+                    let left = self.shl(left, context.new_rvalue_from_long(typ, 15));
+                    let right = self.and(step1, context.new_rvalue_from_long(typ, 0xFFFE0000FFFE0000u64 as i64)); // TODO(antoyo): transmute the number instead?
+                    let right = self.lshr(right, context.new_rvalue_from_long(typ, 17));
+                    let step2 = self.or(left, right);
+
+                    // Third step.
+                    let left = self.lshr(step2, context.new_rvalue_from_long(typ, 10));
+                    let left = self.xor(step2, left);
+                    let temp = self.and(left, context.new_rvalue_from_long(typ, 0x003F801F003F801F));
+
+                    let left = self.shl(temp, context.new_rvalue_from_long(typ, 10));
+                    let left = self.or(temp, left);
+                    let step3 = self.xor(left, step2);
+
+                    // Fourth step.
+                    let left = self.lshr(step3, context.new_rvalue_from_long(typ, 4));
+                    let left = self.xor(step3, left);
+                    let temp = self.and(left, context.new_rvalue_from_long(typ, 0x0E0384210E038421));
+
+                    let left = self.shl(temp, context.new_rvalue_from_long(typ, 4));
+                    let left = self.or(temp, left);
+                    let step4 = self.xor(left, step3);
+
+                    // Fifth step.
+                    let left = self.lshr(step4, context.new_rvalue_from_long(typ, 2));
+                    let left = self.xor(step4, left);
+                    let temp = self.and(left, context.new_rvalue_from_long(typ, 0x2248884222488842));
+
+                    let left = self.shl(temp, context.new_rvalue_from_long(typ, 2));
+                    let left = self.or(temp, left);
+                    let step5 = self.xor(left, step4);
+
+                    step5
+                },
+                128 => {
+                    // TODO(antoyo): find a more efficient implementation?
+                    let sixty_four = self.context.new_rvalue_from_long(typ, 64);
+                    let high = self.context.new_cast(None, value >> sixty_four, self.u64_type);
+                    let low = self.context.new_cast(None, value, self.u64_type);
+
+                    let reversed_high = self.bit_reverse(64, high);
+                    let reversed_low = self.bit_reverse(64, low);
+
+                    let new_low = self.context.new_cast(None, reversed_high, typ);
+                    let new_high = self.context.new_cast(None, reversed_low, typ) << sixty_four;
+
+                    new_low | new_high
+                },
+                _ => {
+                    panic!("cannot bit reverse with width = {}", width);
+                },
+            };
+
+        self.context.new_bitcast(None, result, result_type)
+    }
+
+    fn count_leading_zeroes(&self, width: u64, arg: RValue<'gcc>) -> RValue<'gcc> {
+        // TODO(antoyo): use width?
+        let arg_type = arg.get_type();
+        let count_leading_zeroes =
+            if arg_type.is_uint(&self.cx) {
+                "__builtin_clz"
+            }
+            else if arg_type.is_ulong(&self.cx) {
+                "__builtin_clzl"
+            }
+            else if arg_type.is_ulonglong(&self.cx) {
+                "__builtin_clzll"
+            }
+            else if width == 128 {
+                // Algorithm from: https://stackoverflow.com/a/28433850/389119
+                let array_type = self.context.new_array_type(None, arg_type, 3);
+                let result = self.current_func()
+                    .new_local(None, array_type, "count_loading_zeroes_results");
+
+                let sixty_four = self.context.new_rvalue_from_long(arg_type, 64);
+                let high = self.context.new_cast(None, arg >> sixty_four, self.u64_type);
+                let low = self.context.new_cast(None, arg, self.u64_type);
+
+                let zero = self.context.new_rvalue_zero(self.usize_type);
+                let one = self.context.new_rvalue_one(self.usize_type);
+                let two = self.context.new_rvalue_from_long(self.usize_type, 2);
+
+                let clzll = self.context.get_builtin_function("__builtin_clzll");
+
+                let first_elem = self.context.new_array_access(None, result, zero);
+                let first_value = self.context.new_cast(None, self.context.new_call(None, clzll, &[high]), arg_type);
+                self.llbb()
+                    .add_assignment(None, first_elem, first_value);
+
+                let second_elem = self.context.new_array_access(None, result, one);
+                let second_value = self.context.new_cast(None, self.context.new_call(None, clzll, &[low]), arg_type) + sixty_four;
+                self.llbb()
+                    .add_assignment(None, second_elem, second_value);
+
+                let third_elem = self.context.new_array_access(None, result, two);
+                let third_value = self.context.new_rvalue_from_long(arg_type, 128);
+                self.llbb()
+                    .add_assignment(None, third_elem, third_value);
+
+                let not_high = self.context.new_unary_op(None, UnaryOp::LogicalNegate, self.u64_type, high);
+                let not_low = self.context.new_unary_op(None, UnaryOp::LogicalNegate, self.u64_type, low);
+                let not_low_and_not_high = not_low & not_high;
+                let index = not_high + not_low_and_not_high;
+
+                let res = self.context.new_array_access(None, result, index);
+
+                return self.context.new_cast(None, res, arg_type);
+            }
+            else {
+                let count_leading_zeroes = self.context.get_builtin_function("__builtin_clz");
+                let arg = self.context.new_cast(None, arg, self.uint_type);
+                let diff = self.int_width(self.uint_type) - self.int_width(arg_type);
+                let diff = self.context.new_rvalue_from_long(self.int_type, diff);
+                let res = self.context.new_call(None, count_leading_zeroes, &[arg]) - diff;
+                return self.context.new_cast(None, res, arg_type);
+            };
+        let count_leading_zeroes = self.context.get_builtin_function(count_leading_zeroes);
+        let res = self.context.new_call(None, count_leading_zeroes, &[arg]);
+        self.context.new_cast(None, res, arg_type)
+    }
+
+    fn count_trailing_zeroes(&self, _width: u64, arg: RValue<'gcc>) -> RValue<'gcc> {
+        let result_type = arg.get_type();
+        let arg =
+            if result_type.is_signed(self.cx) {
+                let new_type = result_type.to_unsigned(self.cx);
+                self.context.new_bitcast(None, arg, new_type)
+            }
+            else {
+                arg
+            };
+        let arg_type = arg.get_type();
+        let (count_trailing_zeroes, expected_type) =
+            if arg_type.is_uchar(&self.cx) || arg_type.is_ushort(&self.cx) || arg_type.is_uint(&self.cx) {
+                // NOTE: we don't need to & 0xFF for uchar because the result is undefined on zero.
+                ("__builtin_ctz", self.cx.uint_type)
+            }
+            else if arg_type.is_ulong(&self.cx) {
+                ("__builtin_ctzl", self.cx.ulong_type)
+            }
+            else if arg_type.is_ulonglong(&self.cx) {
+                ("__builtin_ctzll", self.cx.ulonglong_type)
+            }
+            else if arg_type.is_u128(&self.cx) {
+                // Adapted from the algorithm to count leading zeroes from: https://stackoverflow.com/a/28433850/389119
+                let array_type = self.context.new_array_type(None, arg_type, 3);
+                let result = self.current_func()
+                    .new_local(None, array_type, "count_loading_zeroes_results");
+
+                let sixty_four = self.context.new_rvalue_from_long(arg_type, 64);
+                let high = self.context.new_cast(None, arg >> sixty_four, self.u64_type);
+                let low = self.context.new_cast(None, arg, self.u64_type);
+
+                let zero = self.context.new_rvalue_zero(self.usize_type);
+                let one = self.context.new_rvalue_one(self.usize_type);
+                let two = self.context.new_rvalue_from_long(self.usize_type, 2);
+
+                let ctzll = self.context.get_builtin_function("__builtin_ctzll");
+
+                let first_elem = self.context.new_array_access(None, result, zero);
+                let first_value = self.context.new_cast(None, self.context.new_call(None, ctzll, &[low]), arg_type);
+                self.llbb()
+                    .add_assignment(None, first_elem, first_value);
+
+                let second_elem = self.context.new_array_access(None, result, one);
+                let second_value = self.context.new_cast(None, self.context.new_call(None, ctzll, &[high]), arg_type) + sixty_four;
+                self.llbb()
+                    .add_assignment(None, second_elem, second_value);
+
+                let third_elem = self.context.new_array_access(None, result, two);
+                let third_value = self.context.new_rvalue_from_long(arg_type, 128);
+                self.llbb()
+                    .add_assignment(None, third_elem, third_value);
+
+                let not_low = self.context.new_unary_op(None, UnaryOp::LogicalNegate, self.u64_type, low);
+                let not_high = self.context.new_unary_op(None, UnaryOp::LogicalNegate, self.u64_type, high);
+                let not_low_and_not_high = not_low & not_high;
+                let index = not_low + not_low_and_not_high;
+
+                let res = self.context.new_array_access(None, result, index);
+
+                return self.context.new_bitcast(None, res, result_type);
+            }
+            else {
+                unimplemented!("count_trailing_zeroes for {:?}", arg_type);
+            };
+        let count_trailing_zeroes = self.context.get_builtin_function(count_trailing_zeroes);
+        let arg =
+            if arg_type != expected_type {
+                self.context.new_cast(None, arg, expected_type)
+            }
+            else {
+                arg
+            };
+        let res = self.context.new_call(None, count_trailing_zeroes, &[arg]);
+        self.context.new_bitcast(None, res, result_type)
+    }
+
+    fn int_width(&self, typ: Type<'gcc>) -> i64 {
+        self.cx.int_width(typ) as i64
+    }
+
+    fn pop_count(&self, value: RValue<'gcc>) -> RValue<'gcc> {
+        // TODO(antoyo): use the optimized version with fewer operations.
+        let result_type = value.get_type();
+        let value_type = result_type.to_unsigned(self.cx);
+
+        let value =
+            if result_type.is_signed(self.cx) {
+                self.context.new_bitcast(None, value, value_type)
+            }
+            else {
+                value
+            };
+
+        if value_type.is_u128(&self.cx) {
+            // TODO(antoyo): implement in the normal algorithm below to have a more efficient
+            // implementation (that does not require a call to __popcountdi2).
+            let popcount = self.context.get_builtin_function("__builtin_popcountll");
+            let sixty_four = self.context.new_rvalue_from_long(value_type, 64);
+            let high = self.context.new_cast(None, value >> sixty_four, self.cx.ulonglong_type);
+            let high = self.context.new_call(None, popcount, &[high]);
+            let low = self.context.new_cast(None, value, self.cx.ulonglong_type);
+            let low = self.context.new_call(None, popcount, &[low]);
+            let res = high + low;
+            return self.context.new_bitcast(None, res, result_type);
+        }
+
+        // First step.
+        let mask = self.context.new_rvalue_from_long(value_type, 0x5555555555555555);
+        let left = value & mask;
+        let shifted = value >> self.context.new_rvalue_from_int(value_type, 1);
+        let right = shifted & mask;
+        let value = left + right;
+
+        // Second step.
+        let mask = self.context.new_rvalue_from_long(value_type, 0x3333333333333333);
+        let left = value & mask;
+        let shifted = value >> self.context.new_rvalue_from_int(value_type, 2);
+        let right = shifted & mask;
+        let value = left + right;
+
+        // Third step.
+        let mask = self.context.new_rvalue_from_long(value_type, 0x0F0F0F0F0F0F0F0F);
+        let left = value & mask;
+        let shifted = value >> self.context.new_rvalue_from_int(value_type, 4);
+        let right = shifted & mask;
+        let value = left + right;
+
+        if value_type.is_u8(&self.cx) {
+            return self.context.new_bitcast(None, value, result_type);
+        }
+
+        // Fourth step.
+        let mask = self.context.new_rvalue_from_long(value_type, 0x00FF00FF00FF00FF);
+        let left = value & mask;
+        let shifted = value >> self.context.new_rvalue_from_int(value_type, 8);
+        let right = shifted & mask;
+        let value = left + right;
+
+        if value_type.is_u16(&self.cx) {
+            return self.context.new_bitcast(None, value, result_type);
+        }
+
+        // Fifth step.
+        let mask = self.context.new_rvalue_from_long(value_type, 0x0000FFFF0000FFFF);
+        let left = value & mask;
+        let shifted = value >> self.context.new_rvalue_from_int(value_type, 16);
+        let right = shifted & mask;
+        let value = left + right;
+
+        if value_type.is_u32(&self.cx) {
+            return self.context.new_bitcast(None, value, result_type);
+        }
+
+        // Sixth step.
+        let mask = self.context.new_rvalue_from_long(value_type, 0x00000000FFFFFFFF);
+        let left = value & mask;
+        let shifted = value >> self.context.new_rvalue_from_int(value_type, 32);
+        let right = shifted & mask;
+        let value = left + right;
+
+        self.context.new_bitcast(None, value, result_type)
+    }
+
+    // Algorithm from: https://blog.regehr.org/archives/1063
+    fn rotate_left(&mut self, value: RValue<'gcc>, shift: RValue<'gcc>, width: u64) -> RValue<'gcc> {
+        let max = self.context.new_rvalue_from_long(shift.get_type(), width as i64);
+        let shift = shift % max;
+        let lhs = self.shl(value, shift);
+        let result_and =
+            self.and(
+                self.context.new_unary_op(None, UnaryOp::Minus, shift.get_type(), shift),
+                self.context.new_rvalue_from_long(shift.get_type(), width as i64 - 1),
+            );
+        let rhs = self.lshr(value, result_and);
+        self.or(lhs, rhs)
+    }
+
+    // Algorithm from: https://blog.regehr.org/archives/1063
+    fn rotate_right(&mut self, value: RValue<'gcc>, shift: RValue<'gcc>, width: u64) -> RValue<'gcc> {
+        let max = self.context.new_rvalue_from_long(shift.get_type(), width as i64);
+        let shift = shift % max;
+        let lhs = self.lshr(value, shift);
+        let result_and =
+            self.and(
+                self.context.new_unary_op(None, UnaryOp::Minus, shift.get_type(), shift),
+                self.context.new_rvalue_from_long(shift.get_type(), width as i64 - 1),
+            );
+        let rhs = self.shl(value, result_and);
+        self.or(lhs, rhs)
+    }
+
+    fn saturating_add(&mut self, lhs: RValue<'gcc>, rhs: RValue<'gcc>, signed: bool, width: u64) -> RValue<'gcc> {
+        let func = self.current_func.borrow().expect("func");
+
+        if signed {
+            // Algorithm from: https://stackoverflow.com/a/56531252/389119
+            let after_block = func.new_block("after");
+            let func_name =
+                match width {
+                    8 => "__builtin_add_overflow",
+                    16 => "__builtin_add_overflow",
+                    32 => "__builtin_sadd_overflow",
+                    64 => "__builtin_saddll_overflow",
+                    128 => "__builtin_add_overflow",
+                    _ => unreachable!(),
+                };
+            let overflow_func = self.context.get_builtin_function(func_name);
+            let result_type = lhs.get_type();
+            let res = func.new_local(None, result_type, "saturating_sum");
+            let overflow = self.overflow_call(overflow_func, &[lhs, rhs, res.get_address(None)], None);
+
+            let then_block = func.new_block("then");
+
+            let unsigned_type = self.context.new_int_type(width as i32 / 8, false);
+            let shifted = self.context.new_cast(None, lhs, unsigned_type) >> self.context.new_rvalue_from_int(unsigned_type, width as i32 - 1);
+            let uint_max = self.context.new_unary_op(None, UnaryOp::BitwiseNegate, unsigned_type,
+                self.context.new_rvalue_from_int(unsigned_type, 0)
+            );
+            let int_max = uint_max >> self.context.new_rvalue_one(unsigned_type);
+            then_block.add_assignment(None, res, self.context.new_cast(None, shifted + int_max, result_type));
+            then_block.end_with_jump(None, after_block);
+
+            self.llbb().end_with_conditional(None, overflow, then_block, after_block);
+
+            // NOTE: since jumps were added in a place rustc does not
+            // expect, the current blocks in the state need to be updated.
+            *self.current_block.borrow_mut() = Some(after_block);
+            self.block = Some(after_block);
+
+            res.to_rvalue()
+        }
+        else {
+            // Algorithm from: http://locklessinc.com/articles/sat_arithmetic/
+            let res = lhs + rhs;
+            let res_type = res.get_type();
+            let cond = self.context.new_comparison(None, ComparisonOp::LessThan, res, lhs);
+            let value = self.context.new_unary_op(None, UnaryOp::Minus, res_type, self.context.new_cast(None, cond, res_type));
+            res | value
+        }
+    }
+
+    // Algorithm from: https://locklessinc.com/articles/sat_arithmetic/
+    fn saturating_sub(&mut self, lhs: RValue<'gcc>, rhs: RValue<'gcc>, signed: bool, width: u64) -> RValue<'gcc> {
+        if signed {
+            // Also based on algorithm from: https://stackoverflow.com/a/56531252/389119
+            let func_name =
+                match width {
+                    8 => "__builtin_sub_overflow",
+                    16 => "__builtin_sub_overflow",
+                    32 => "__builtin_ssub_overflow",
+                    64 => "__builtin_ssubll_overflow",
+                    128 => "__builtin_sub_overflow",
+                    _ => unreachable!(),
+                };
+            let overflow_func = self.context.get_builtin_function(func_name);
+            let result_type = lhs.get_type();
+            let func = self.current_func.borrow().expect("func");
+            let res = func.new_local(None, result_type, "saturating_diff");
+            let overflow = self.overflow_call(overflow_func, &[lhs, rhs, res.get_address(None)], None);
+
+            let then_block = func.new_block("then");
+            let after_block = func.new_block("after");
+
+            let unsigned_type = self.context.new_int_type(width as i32 / 8, false);
+            let shifted = self.context.new_cast(None, lhs, unsigned_type) >> self.context.new_rvalue_from_int(unsigned_type, width as i32 - 1);
+            let uint_max = self.context.new_unary_op(None, UnaryOp::BitwiseNegate, unsigned_type,
+                self.context.new_rvalue_from_int(unsigned_type, 0)
+            );
+            let int_max = uint_max >> self.context.new_rvalue_one(unsigned_type);
+            then_block.add_assignment(None, res, self.context.new_cast(None, shifted + int_max, result_type));
+            then_block.end_with_jump(None, after_block);
+
+            self.llbb().end_with_conditional(None, overflow, then_block, after_block);
+
+            // NOTE: since jumps were added in a place rustc does not
+            // expect, the current blocks in the state need to be updated.
+            *self.current_block.borrow_mut() = Some(after_block);
+            self.block = Some(after_block);
+
+            res.to_rvalue()
+        }
+        else {
+            let res = lhs - rhs;
+            let comparison = self.context.new_comparison(None, ComparisonOp::LessThanEquals, res, lhs);
+            let comparison = self.context.new_cast(None, comparison, lhs.get_type());
+            let unary_op = self.context.new_unary_op(None, UnaryOp::Minus, comparison.get_type(), comparison);
+            self.and(res, unary_op)
+        }
+    }
+}
+
+fn try_intrinsic<'gcc, 'tcx>(bx: &mut Builder<'_, 'gcc, 'tcx>, try_func: RValue<'gcc>, data: RValue<'gcc>, _catch_func: RValue<'gcc>, dest: RValue<'gcc>) {
+    if bx.sess().panic_strategy() == PanicStrategy::Abort {
+        bx.call(bx.type_void(), try_func, &[data], None);
+        // Return 0 unconditionally from the intrinsic call;
+        // we can never unwind.
+        let ret_align = bx.tcx.data_layout.i32_align.abi;
+        bx.store(bx.const_i32(0), dest, ret_align);
+    }
+    else if wants_msvc_seh(bx.sess()) {
+        unimplemented!();
+    }
+    else {
+        unimplemented!();
+    }
+}
diff --git a/compiler/rustc_codegen_gcc/src/intrinsic/simd.rs b/compiler/rustc_codegen_gcc/src/intrinsic/simd.rs
new file mode 100644
index 00000000000..26a42217e4c
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/intrinsic/simd.rs
@@ -0,0 +1,167 @@
+use gccjit::{RValue, Type};
+use rustc_codegen_ssa::base::compare_simd_types;
+use rustc_codegen_ssa::common::{TypeKind, span_invalid_monomorphization_error};
+use rustc_codegen_ssa::mir::operand::OperandRef;
+use rustc_codegen_ssa::traits::{BaseTypeMethods, BuilderMethods};
+use rustc_hir as hir;
+use rustc_middle::span_bug;
+use rustc_middle::ty::layout::HasTyCtxt;
+use rustc_middle::ty::{self, Ty};
+use rustc_span::{Span, Symbol, sym};
+
+use crate::builder::Builder;
+
+pub fn generic_simd_intrinsic<'a, 'gcc, 'tcx>(bx: &mut Builder<'a, 'gcc, 'tcx>, name: Symbol, callee_ty: Ty<'tcx>, args: &[OperandRef<'tcx, RValue<'gcc>>], ret_ty: Ty<'tcx>, llret_ty: Type<'gcc>, span: Span) -> Result<RValue<'gcc>, ()> {
+    // macros for error handling:
+    macro_rules! emit_error {
+        ($msg: tt) => {
+            emit_error!($msg, )
+        };
+        ($msg: tt, $($fmt: tt)*) => {
+            span_invalid_monomorphization_error(
+                bx.sess(), span,
+                &format!(concat!("invalid monomorphization of `{}` intrinsic: ", $msg),
+                         name, $($fmt)*));
+        }
+    }
+
+    macro_rules! return_error {
+        ($($fmt: tt)*) => {
+            {
+                emit_error!($($fmt)*);
+                return Err(());
+            }
+        }
+    }
+
+    macro_rules! require {
+        ($cond: expr, $($fmt: tt)*) => {
+            if !$cond {
+                return_error!($($fmt)*);
+            }
+        };
+    }
+
+    macro_rules! require_simd {
+        ($ty: expr, $position: expr) => {
+            require!($ty.is_simd(), "expected SIMD {} type, found non-SIMD `{}`", $position, $ty)
+        };
+    }
+
+    let tcx = bx.tcx();
+    let sig =
+        tcx.normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), callee_ty.fn_sig(tcx));
+    let arg_tys = sig.inputs();
+    let name_str = &*name.as_str();
+
+    // every intrinsic below takes a SIMD vector as its first argument
+    require_simd!(arg_tys[0], "input");
+    let in_ty = arg_tys[0];
+
+    let comparison = match name {
+        sym::simd_eq => Some(hir::BinOpKind::Eq),
+        sym::simd_ne => Some(hir::BinOpKind::Ne),
+        sym::simd_lt => Some(hir::BinOpKind::Lt),
+        sym::simd_le => Some(hir::BinOpKind::Le),
+        sym::simd_gt => Some(hir::BinOpKind::Gt),
+        sym::simd_ge => Some(hir::BinOpKind::Ge),
+        _ => None,
+    };
+
+    let (in_len, in_elem) = arg_tys[0].simd_size_and_type(bx.tcx());
+    if let Some(cmp_op) = comparison {
+        require_simd!(ret_ty, "return");
+
+        let (out_len, out_ty) = ret_ty.simd_size_and_type(bx.tcx());
+        require!(
+            in_len == out_len,
+            "expected return type with length {} (same as input type `{}`), \
+             found `{}` with length {}",
+            in_len,
+            in_ty,
+            ret_ty,
+            out_len
+        );
+        require!(
+            bx.type_kind(bx.element_type(llret_ty)) == TypeKind::Integer,
+            "expected return type with integer elements, found `{}` with non-integer `{}`",
+            ret_ty,
+            out_ty
+        );
+
+        return Ok(compare_simd_types(
+            bx,
+            args[0].immediate(),
+            args[1].immediate(),
+            in_elem,
+            llret_ty,
+            cmp_op,
+        ));
+    }
+
+    if let Some(stripped) = name_str.strip_prefix("simd_shuffle") {
+        let n: u64 = stripped.parse().unwrap_or_else(|_| {
+            span_bug!(span, "bad `simd_shuffle` instruction only caught in codegen?")
+        });
+
+        require_simd!(ret_ty, "return");
+
+        let (out_len, out_ty) = ret_ty.simd_size_and_type(bx.tcx());
+        require!(
+            out_len == n,
+            "expected return type of length {}, found `{}` with length {}",
+            n,
+            ret_ty,
+            out_len
+        );
+        require!(
+            in_elem == out_ty,
+            "expected return element type `{}` (element of input `{}`), \
+             found `{}` with element type `{}`",
+            in_elem,
+            in_ty,
+            ret_ty,
+            out_ty
+        );
+
+        let vector = args[2].immediate();
+
+        return Ok(bx.shuffle_vector(
+            args[0].immediate(),
+            args[1].immediate(),
+            vector,
+        ));
+    }
+
+    macro_rules! arith_binary {
+        ($($name: ident: $($($p: ident),* => $call: ident),*;)*) => {
+            $(if name == sym::$name {
+                match in_elem.kind() {
+                    $($(ty::$p(_))|* => {
+                        return Ok(bx.$call(args[0].immediate(), args[1].immediate()))
+                    })*
+                    _ => {},
+                }
+                require!(false,
+                         "unsupported operation on `{}` with element `{}`",
+                         in_ty,
+                         in_elem)
+            })*
+        }
+    }
+
+    arith_binary! {
+        simd_add: Uint, Int => add, Float => fadd;
+        simd_sub: Uint, Int => sub, Float => fsub;
+        simd_mul: Uint, Int => mul, Float => fmul;
+        simd_div: Uint => udiv, Int => sdiv, Float => fdiv;
+        simd_rem: Uint => urem, Int => srem, Float => frem;
+        simd_shl: Uint, Int => shl;
+        simd_shr: Uint => lshr, Int => ashr;
+        simd_and: Uint, Int => and;
+        simd_or: Uint, Int => or; // FIXME(antoyo): calling `or` might not work on vectors.
+        simd_xor: Uint, Int => xor;
+    }
+
+    unimplemented!("simd {}", name);
+}
diff --git a/compiler/rustc_codegen_gcc/src/lib.rs b/compiler/rustc_codegen_gcc/src/lib.rs
new file mode 100644
index 00000000000..629003d7982
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/lib.rs
@@ -0,0 +1,293 @@
+/*
+ * TODO(antoyo): support #[inline] attributes.
+ * TODO(antoyo): support LTO.
+ *
+ * TODO(antoyo): remove the patches.
+ */
+
+#![feature(rustc_private, decl_macro, associated_type_bounds, never_type, trusted_len)]
+#![allow(broken_intra_doc_links)]
+#![recursion_limit="256"]
+#![warn(rust_2018_idioms)]
+#![warn(unused_lifetimes)]
+
+extern crate rustc_ast;
+extern crate rustc_codegen_ssa;
+extern crate rustc_data_structures;
+extern crate rustc_errors;
+extern crate rustc_hir;
+extern crate rustc_metadata;
+extern crate rustc_middle;
+extern crate rustc_session;
+extern crate rustc_span;
+extern crate rustc_symbol_mangling;
+extern crate rustc_target;
+extern crate snap;
+
+// This prevents duplicating functions and statics that are already part of the host rustc process.
+#[allow(unused_extern_crates)]
+extern crate rustc_driver;
+
+mod abi;
+mod allocator;
+mod archive;
+mod asm;
+mod back;
+mod base;
+mod builder;
+mod callee;
+mod common;
+mod consts;
+mod context;
+mod coverageinfo;
+mod debuginfo;
+mod declare;
+mod intrinsic;
+mod mono_item;
+mod type_;
+mod type_of;
+
+use std::any::Any;
+use std::sync::Arc;
+
+use gccjit::{Context, OptimizationLevel};
+use rustc_ast::expand::allocator::AllocatorKind;
+use rustc_codegen_ssa::{CodegenResults, CompiledModule, ModuleCodegen};
+use rustc_codegen_ssa::base::codegen_crate;
+use rustc_codegen_ssa::back::write::{CodegenContext, FatLTOInput, ModuleConfig, TargetMachineFactoryFn};
+use rustc_codegen_ssa::back::lto::{LtoModuleCodegen, SerializedModule, ThinModule};
+use rustc_codegen_ssa::target_features::supported_target_features;
+use rustc_codegen_ssa::traits::{CodegenBackend, ExtraBackendMethods, ModuleBufferMethods, ThinBufferMethods, WriteBackendMethods};
+use rustc_data_structures::fx::FxHashMap;
+use rustc_errors::{ErrorReported, Handler};
+use rustc_metadata::EncodedMetadata;
+use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
+use rustc_middle::ty::TyCtxt;
+use rustc_session::config::{Lto, OptLevel, OutputFilenames};
+use rustc_session::Session;
+use rustc_span::Symbol;
+use rustc_span::fatal_error::FatalError;
+
+pub struct PrintOnPanic<F: Fn() -> String>(pub F);
+
+impl<F: Fn() -> String> Drop for PrintOnPanic<F> {
+    fn drop(&mut self) {
+        if ::std::thread::panicking() {
+            println!("{}", (self.0)());
+        }
+    }
+}
+
+#[derive(Clone)]
+pub struct GccCodegenBackend;
+
+impl CodegenBackend for GccCodegenBackend {
+    fn init(&self, sess: &Session) {
+        if sess.lto() != Lto::No {
+            sess.warn("LTO is not supported. You may get a linker error.");
+        }
+    }
+
+    fn codegen_crate<'tcx>(&self, tcx: TyCtxt<'tcx>, metadata: EncodedMetadata, need_metadata_module: bool) -> Box<dyn Any> {
+        let target_cpu = target_cpu(tcx.sess);
+        let res = codegen_crate(self.clone(), tcx, target_cpu.to_string(), metadata, need_metadata_module);
+
+        rustc_symbol_mangling::test::report_symbol_names(tcx);
+
+        Box::new(res)
+    }
+
+    fn join_codegen(&self, ongoing_codegen: Box<dyn Any>, sess: &Session) -> Result<(CodegenResults, FxHashMap<WorkProductId, WorkProduct>), ErrorReported> {
+        let (codegen_results, work_products) = ongoing_codegen
+            .downcast::<rustc_codegen_ssa::back::write::OngoingCodegen<GccCodegenBackend>>()
+            .expect("Expected GccCodegenBackend's OngoingCodegen, found Box<Any>")
+            .join(sess);
+
+        Ok((codegen_results, work_products))
+    }
+
+    fn link(&self, sess: &Session, codegen_results: CodegenResults, outputs: &OutputFilenames) -> Result<(), ErrorReported> {
+        use rustc_codegen_ssa::back::link::link_binary;
+
+        link_binary::<crate::archive::ArArchiveBuilder<'_>>(
+            sess,
+            &codegen_results,
+            outputs,
+        )
+    }
+
+    fn target_features(&self, sess: &Session) -> Vec<Symbol> {
+        target_features(sess)
+    }
+}
+
+impl ExtraBackendMethods for GccCodegenBackend {
+    fn new_metadata<'tcx>(&self, _tcx: TyCtxt<'tcx>, _mod_name: &str) -> Self::Module {
+        GccContext {
+            context: Context::default(),
+        }
+    }
+
+    fn write_compressed_metadata<'tcx>(&self, tcx: TyCtxt<'tcx>, metadata: &EncodedMetadata, gcc_module: &mut Self::Module) {
+        base::write_compressed_metadata(tcx, metadata, gcc_module)
+    }
+
+    fn codegen_allocator<'tcx>(&self, tcx: TyCtxt<'tcx>, mods: &mut Self::Module, module_name: &str, kind: AllocatorKind, has_alloc_error_handler: bool) {
+        unsafe { allocator::codegen(tcx, mods, module_name, kind, has_alloc_error_handler) }
+    }
+
+    fn compile_codegen_unit<'tcx>(&self, tcx: TyCtxt<'tcx>, cgu_name: Symbol) -> (ModuleCodegen<Self::Module>, u64) {
+        base::compile_codegen_unit(tcx, cgu_name)
+    }
+
+    fn target_machine_factory(&self, _sess: &Session, _opt_level: OptLevel) -> TargetMachineFactoryFn<Self> {
+        // TODO(antoyo): set opt level.
+        Arc::new(|_| {
+            Ok(())
+        })
+    }
+
+    fn target_cpu<'b>(&self, _sess: &'b Session) -> &'b str {
+        unimplemented!();
+    }
+
+    fn tune_cpu<'b>(&self, _sess: &'b Session) -> Option<&'b str> {
+        None
+        // TODO(antoyo)
+    }
+}
+
+pub struct ModuleBuffer;
+
+impl ModuleBufferMethods for ModuleBuffer {
+    fn data(&self) -> &[u8] {
+        unimplemented!();
+    }
+}
+
+pub struct ThinBuffer;
+
+impl ThinBufferMethods for ThinBuffer {
+    fn data(&self) -> &[u8] {
+        unimplemented!();
+    }
+}
+
+pub struct GccContext {
+    context: Context<'static>,
+}
+
+unsafe impl Send for GccContext {}
+// FIXME(antoyo): that shouldn't be Sync. Parallel compilation is currently disabled with "-Zno-parallel-llvm". Try to disable it here.
+unsafe impl Sync for GccContext {}
+
+impl WriteBackendMethods for GccCodegenBackend {
+    type Module = GccContext;
+    type TargetMachine = ();
+    type ModuleBuffer = ModuleBuffer;
+    type Context = ();
+    type ThinData = ();
+    type ThinBuffer = ThinBuffer;
+
+    fn run_fat_lto(_cgcx: &CodegenContext<Self>, mut modules: Vec<FatLTOInput<Self>>, _cached_modules: Vec<(SerializedModule<Self::ModuleBuffer>, WorkProduct)>) -> Result<LtoModuleCodegen<Self>, FatalError> {
+        // TODO(antoyo): implement LTO by sending -flto to libgccjit and adding the appropriate gcc linker plugins.
+        // NOTE: implemented elsewhere.
+        // TODO: what is implemented elsewhere ^ ?
+        let module =
+            match modules.remove(0) {
+                FatLTOInput::InMemory(module) => module,
+                FatLTOInput::Serialized { .. } => {
+                    unimplemented!();
+                }
+            };
+        Ok(LtoModuleCodegen::Fat { module: Some(module), _serialized_bitcode: vec![] })
+    }
+
+    fn run_thin_lto(_cgcx: &CodegenContext<Self>, _modules: Vec<(String, Self::ThinBuffer)>, _cached_modules: Vec<(SerializedModule<Self::ModuleBuffer>, WorkProduct)>) -> Result<(Vec<LtoModuleCodegen<Self>>, Vec<WorkProduct>), FatalError> {
+        unimplemented!();
+    }
+
+    fn print_pass_timings(&self) {
+        unimplemented!();
+    }
+
+    unsafe fn optimize(_cgcx: &CodegenContext<Self>, _diag_handler: &Handler, module: &ModuleCodegen<Self::Module>, config: &ModuleConfig) -> Result<(), FatalError> {
+        module.module_llvm.context.set_optimization_level(to_gcc_opt_level(config.opt_level));
+        Ok(())
+    }
+
+    unsafe fn optimize_thin(_cgcx: &CodegenContext<Self>, _thin: &mut ThinModule<Self>) -> Result<ModuleCodegen<Self::Module>, FatalError> {
+        unimplemented!();
+    }
+
+    unsafe fn codegen(cgcx: &CodegenContext<Self>, diag_handler: &Handler, module: ModuleCodegen<Self::Module>, config: &ModuleConfig) -> Result<CompiledModule, FatalError> {
+        back::write::codegen(cgcx, diag_handler, module, config)
+    }
+
+    fn prepare_thin(_module: ModuleCodegen<Self::Module>) -> (String, Self::ThinBuffer) {
+        unimplemented!();
+    }
+
+    fn serialize_module(_module: ModuleCodegen<Self::Module>) -> (String, Self::ModuleBuffer) {
+        unimplemented!();
+    }
+
+    fn run_lto_pass_manager(_cgcx: &CodegenContext<Self>, _module: &ModuleCodegen<Self::Module>, _config: &ModuleConfig, _thin: bool) -> Result<(), FatalError> {
+        // TODO(antoyo)
+        Ok(())
+    }
+
+    fn run_link(cgcx: &CodegenContext<Self>, diag_handler: &Handler, modules: Vec<ModuleCodegen<Self::Module>>) -> Result<ModuleCodegen<Self::Module>, FatalError> {
+        back::write::link(cgcx, diag_handler, modules)
+    }
+}
+
+/// This is the entrypoint for a hot plugged rustc_codegen_gccjit
+#[no_mangle]
+pub fn __rustc_codegen_backend() -> Box<dyn CodegenBackend> {
+    Box::new(GccCodegenBackend)
+}
+
+fn to_gcc_opt_level(optlevel: Option<OptLevel>) -> OptimizationLevel {
+    match optlevel {
+        None => OptimizationLevel::None,
+        Some(level) => {
+            match level {
+                OptLevel::No => OptimizationLevel::None,
+                OptLevel::Less => OptimizationLevel::Limited,
+                OptLevel::Default => OptimizationLevel::Standard,
+                OptLevel::Aggressive => OptimizationLevel::Aggressive,
+                OptLevel::Size | OptLevel::SizeMin => OptimizationLevel::Limited,
+            }
+        },
+    }
+}
+
+fn handle_native(name: &str) -> &str {
+    if name != "native" {
+        return name;
+    }
+
+    unimplemented!();
+}
+
+pub fn target_cpu(sess: &Session) -> &str {
+    let name = sess.opts.cg.target_cpu.as_ref().unwrap_or(&sess.target.cpu);
+    handle_native(name)
+}
+
+pub fn target_features(sess: &Session) -> Vec<Symbol> {
+    supported_target_features(sess)
+        .iter()
+        .filter_map(
+            |&(feature, gate)| {
+                if sess.is_nightly_build() || gate.is_none() { Some(feature) } else { None }
+            },
+        )
+        .filter(|_feature| {
+            // TODO(antoyo): implement a way to get enabled feature in libgccjit.
+            false
+        })
+        .map(|feature| Symbol::intern(feature))
+        .collect()
+}
diff --git a/compiler/rustc_codegen_gcc/src/mono_item.rs b/compiler/rustc_codegen_gcc/src/mono_item.rs
new file mode 100644
index 00000000000..e21d40b6c37
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/mono_item.rs
@@ -0,0 +1,38 @@
+use rustc_codegen_ssa::traits::PreDefineMethods;
+use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
+use rustc_middle::mir::mono::{Linkage, Visibility};
+use rustc_middle::ty::{self, Instance, TypeFoldable};
+use rustc_middle::ty::layout::{FnAbiOf, LayoutOf};
+use rustc_span::def_id::DefId;
+
+use crate::base;
+use crate::context::CodegenCx;
+use crate::type_of::LayoutGccExt;
+
+impl<'gcc, 'tcx> PreDefineMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
+    fn predefine_static(&self, def_id: DefId, _linkage: Linkage, _visibility: Visibility, symbol_name: &str) {
+        let attrs = self.tcx.codegen_fn_attrs(def_id);
+        let instance = Instance::mono(self.tcx, def_id);
+        let ty = instance.ty(self.tcx, ty::ParamEnv::reveal_all());
+        let gcc_type = self.layout_of(ty).gcc_type(self, true);
+
+        let is_tls = attrs.flags.contains(CodegenFnAttrFlags::THREAD_LOCAL);
+        let global = self.define_global(symbol_name, gcc_type, is_tls, attrs.link_section);
+
+        // TODO(antoyo): set linkage and visibility.
+        self.instances.borrow_mut().insert(instance, global);
+    }
+
+    fn predefine_fn(&self, instance: Instance<'tcx>, linkage: Linkage, _visibility: Visibility, symbol_name: &str) {
+        assert!(!instance.substs.needs_infer());
+
+        let fn_abi = self.fn_abi_of_instance(instance, ty::List::empty());
+        self.linkage.set(base::linkage_to_gcc(linkage));
+        let _decl = self.declare_fn(symbol_name, &fn_abi);
+        //let attrs = self.tcx.codegen_fn_attrs(instance.def_id());
+
+        // TODO(antoyo): call set_link_section() to allow initializing argc/argv.
+        // TODO(antoyo): set unique comdat.
+        // TODO(antoyo): use inline attribute from there in linkage.set() above.
+    }
+}
diff --git a/compiler/rustc_codegen_gcc/src/type_.rs b/compiler/rustc_codegen_gcc/src/type_.rs
new file mode 100644
index 00000000000..3545e1b6281
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/type_.rs
@@ -0,0 +1,282 @@
+use std::convert::TryInto;
+
+use gccjit::{RValue, Struct, Type};
+use rustc_codegen_ssa::traits::{BaseTypeMethods, DerivedTypeMethods};
+use rustc_codegen_ssa::common::TypeKind;
+use rustc_middle::bug;
+use rustc_middle::ty::layout::TyAndLayout;
+use rustc_target::abi::{AddressSpace, Align, Integer, Size};
+
+use crate::common::TypeReflection;
+use crate::context::CodegenCx;
+use crate::type_of::LayoutGccExt;
+
+impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
+    pub fn type_ix(&self, num_bits: u64) -> Type<'gcc> {
+        // gcc only supports 1, 2, 4 or 8-byte integers.
+        // FIXME(antoyo): this is misleading to use the next power of two as rustc_codegen_ssa
+        // sometimes use 96-bit numbers and the following code will give an integer of a different
+        // size.
+        let bytes = (num_bits / 8).next_power_of_two() as i32;
+        match bytes {
+            1 => self.i8_type,
+            2 => self.i16_type,
+            4 => self.i32_type,
+            8 => self.i64_type,
+            16 => self.i128_type,
+            _ => panic!("unexpected num_bits: {}", num_bits),
+        }
+    }
+
+    pub fn type_void(&self) -> Type<'gcc> {
+        self.context.new_type::<()>()
+    }
+
+    pub fn type_size_t(&self) -> Type<'gcc> {
+        self.context.new_type::<usize>()
+    }
+
+    pub fn type_u8(&self) -> Type<'gcc> {
+        self.u8_type
+    }
+
+    pub fn type_u16(&self) -> Type<'gcc> {
+        self.u16_type
+    }
+
+    pub fn type_u32(&self) -> Type<'gcc> {
+        self.u32_type
+    }
+
+    pub fn type_u64(&self) -> Type<'gcc> {
+        self.u64_type
+    }
+
+    pub fn type_u128(&self) -> Type<'gcc> {
+        self.u128_type
+    }
+
+    pub fn type_pointee_for_align(&self, align: Align) -> Type<'gcc> {
+        // FIXME(eddyb) We could find a better approximation if ity.align < align.
+        let ity = Integer::approximate_align(self, align);
+        self.type_from_integer(ity)
+    }
+}
+
+impl<'gcc, 'tcx> BaseTypeMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
+    fn type_i1(&self) -> Type<'gcc> {
+        self.bool_type
+    }
+
+    fn type_i8(&self) -> Type<'gcc> {
+        self.i8_type
+    }
+
+    fn type_i16(&self) -> Type<'gcc> {
+        self.i16_type
+    }
+
+    fn type_i32(&self) -> Type<'gcc> {
+        self.i32_type
+    }
+
+    fn type_i64(&self) -> Type<'gcc> {
+        self.i64_type
+    }
+
+    fn type_i128(&self) -> Type<'gcc> {
+        self.i128_type
+    }
+
+    fn type_isize(&self) -> Type<'gcc> {
+        self.isize_type
+    }
+
+    fn type_f32(&self) -> Type<'gcc> {
+        self.context.new_type::<f32>()
+    }
+
+    fn type_f64(&self) -> Type<'gcc> {
+        self.context.new_type::<f64>()
+    }
+
+    fn type_func(&self, params: &[Type<'gcc>], return_type: Type<'gcc>) -> Type<'gcc> {
+        self.context.new_function_pointer_type(None, return_type, params, false)
+    }
+
+    fn type_struct(&self, fields: &[Type<'gcc>], _packed: bool) -> Type<'gcc> {
+        let types = fields.to_vec();
+        if let Some(typ) = self.struct_types.borrow().get(fields) {
+            return typ.clone();
+        }
+        let fields: Vec<_> = fields.iter().enumerate()
+            .map(|(index, field)| self.context.new_field(None, *field, &format!("field{}_TODO", index)))
+            .collect();
+        // TODO(antoyo): use packed.
+        let typ = self.context.new_struct_type(None, "struct", &fields).as_type();
+        self.struct_types.borrow_mut().insert(types, typ);
+        typ
+    }
+
+    fn type_kind(&self, typ: Type<'gcc>) -> TypeKind {
+        if typ.is_integral() {
+            TypeKind::Integer
+        }
+        else if typ.is_vector().is_some() {
+            TypeKind::Vector
+        }
+        else {
+            // TODO(antoyo): support other types.
+            TypeKind::Void
+        }
+    }
+
+    fn type_ptr_to(&self, ty: Type<'gcc>) -> Type<'gcc> {
+        ty.make_pointer()
+    }
+
+    fn type_ptr_to_ext(&self, ty: Type<'gcc>, _address_space: AddressSpace) -> Type<'gcc> {
+        // TODO(antoyo): use address_space
+        ty.make_pointer()
+    }
+
+    fn element_type(&self, ty: Type<'gcc>) -> Type<'gcc> {
+        if let Some(typ) = ty.is_array() {
+            typ
+        }
+        else if let Some(vector_type) = ty.is_vector() {
+            vector_type.get_element_type()
+        }
+        else if let Some(typ) = ty.get_pointee() {
+            typ
+        }
+        else {
+            unreachable!()
+        }
+    }
+
+    fn vector_length(&self, _ty: Type<'gcc>) -> usize {
+        unimplemented!();
+    }
+
+    fn float_width(&self, typ: Type<'gcc>) -> usize {
+        let f32 = self.context.new_type::<f32>();
+        let f64 = self.context.new_type::<f64>();
+        if typ == f32 {
+            32
+        }
+        else if typ == f64 {
+            64
+        }
+        else {
+            panic!("Cannot get width of float type {:?}", typ);
+        }
+        // TODO(antoyo): support other sizes.
+    }
+
+    fn int_width(&self, typ: Type<'gcc>) -> u64 {
+        if typ.is_i8(self) || typ.is_u8(self) {
+            8
+        }
+        else if typ.is_i16(self) || typ.is_u16(self) {
+            16
+        }
+        else if typ.is_i32(self) || typ.is_u32(self) {
+            32
+        }
+        else if typ.is_i64(self) || typ.is_u64(self) {
+            64
+        }
+        else if typ.is_i128(self) || typ.is_u128(self) {
+            128
+        }
+        else {
+            panic!("Cannot get width of int type {:?}", typ);
+        }
+    }
+
+    fn val_ty(&self, value: RValue<'gcc>) -> Type<'gcc> {
+        value.get_type()
+    }
+}
+
+impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
+    pub fn type_padding_filler(&self, size: Size, align: Align) -> Type<'gcc> {
+        let unit = Integer::approximate_align(self, align);
+        let size = size.bytes();
+        let unit_size = unit.size().bytes();
+        assert_eq!(size % unit_size, 0);
+        self.type_array(self.type_from_integer(unit), size / unit_size)
+    }
+
+    pub fn set_struct_body(&self, typ: Struct<'gcc>, fields: &[Type<'gcc>], _packed: bool) {
+        // TODO(antoyo): use packed.
+        let fields: Vec<_> = fields.iter().enumerate()
+            .map(|(index, field)| self.context.new_field(None, *field, &format!("field_{}", index)))
+            .collect();
+        typ.set_fields(None, &fields);
+    }
+
+    pub fn type_named_struct(&self, name: &str) -> Struct<'gcc> {
+        self.context.new_opaque_struct_type(None, name)
+    }
+
+    pub fn type_array(&self, ty: Type<'gcc>, mut len: u64) -> Type<'gcc> {
+        if let Some(struct_type) = ty.is_struct() {
+            if struct_type.get_field_count() == 0 {
+                // NOTE: since gccjit only supports i32 for the array size and libcore's tests uses a
+                // size of usize::MAX in test_binary_search, we workaround this by setting the size to
+                // zero for ZSTs.
+                // FIXME(antoyo): fix gccjit API.
+                len = 0;
+            }
+        }
+
+        // NOTE: see note above. Some other test uses usize::MAX.
+        if len == u64::MAX {
+            len = 0;
+        }
+
+        let len: i32 = len.try_into().expect("array len");
+
+        self.context.new_array_type(None, ty, len)
+    }
+}
+
+pub fn struct_fields<'gcc, 'tcx>(cx: &CodegenCx<'gcc, 'tcx>, layout: TyAndLayout<'tcx>) -> (Vec<Type<'gcc>>, bool) {
+    let field_count = layout.fields.count();
+
+    let mut packed = false;
+    let mut offset = Size::ZERO;
+    let mut prev_effective_align = layout.align.abi;
+    let mut result: Vec<_> = Vec::with_capacity(1 + field_count * 2);
+    for i in layout.fields.index_by_increasing_offset() {
+        let target_offset = layout.fields.offset(i as usize);
+        let field = layout.field(cx, i);
+        let effective_field_align =
+            layout.align.abi.min(field.align.abi).restrict_for_offset(target_offset);
+        packed |= effective_field_align < field.align.abi;
+
+        assert!(target_offset >= offset);
+        let padding = target_offset - offset;
+        let padding_align = prev_effective_align.min(effective_field_align);
+        assert_eq!(offset.align_to(padding_align) + padding, target_offset);
+        result.push(cx.type_padding_filler(padding, padding_align));
+
+        result.push(field.gcc_type(cx, !field.ty.is_any_ptr())); // FIXME(antoyo): might need to check if the type is inside another, like Box<Type>.
+        offset = target_offset + field.size;
+        prev_effective_align = effective_field_align;
+    }
+    if !layout.is_unsized() && field_count > 0 {
+        if offset > layout.size {
+            bug!("layout: {:#?} stride: {:?} offset: {:?}", layout, layout.size, offset);
+        }
+        let padding = layout.size - offset;
+        let padding_align = prev_effective_align;
+        assert_eq!(offset.align_to(padding_align) + padding, layout.size);
+        result.push(cx.type_padding_filler(padding, padding_align));
+        assert_eq!(result.len(), 1 + field_count * 2);
+    }
+
+    (result, packed)
+}
diff --git a/compiler/rustc_codegen_gcc/src/type_of.rs b/compiler/rustc_codegen_gcc/src/type_of.rs
new file mode 100644
index 00000000000..9c39c8f91a1
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/src/type_of.rs
@@ -0,0 +1,359 @@
+use std::fmt::Write;
+
+use gccjit::{Struct, Type};
+use crate::rustc_codegen_ssa::traits::{BaseTypeMethods, DerivedTypeMethods, LayoutTypeMethods};
+use rustc_middle::bug;
+use rustc_middle::ty::{self, Ty, TypeFoldable};
+use rustc_middle::ty::layout::{FnAbiOf, LayoutOf, TyAndLayout};
+use rustc_middle::ty::print::with_no_trimmed_paths;
+use rustc_target::abi::{self, Abi, F32, F64, FieldsShape, Int, Integer, Pointer, PointeeInfo, Size, TyAbiInterface, Variants};
+use rustc_target::abi::call::{CastTarget, FnAbi, Reg};
+
+use crate::abi::{FnAbiGccExt, GccType};
+use crate::context::CodegenCx;
+use crate::type_::struct_fields;
+
+impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
+    fn type_from_unsigned_integer(&self, i: Integer) -> Type<'gcc> {
+        use Integer::*;
+        match i {
+            I8 => self.type_u8(),
+            I16 => self.type_u16(),
+            I32 => self.type_u32(),
+            I64 => self.type_u64(),
+            I128 => self.type_u128(),
+        }
+    }
+}
+
+pub fn uncached_gcc_type<'gcc, 'tcx>(cx: &CodegenCx<'gcc, 'tcx>, layout: TyAndLayout<'tcx>, defer: &mut Option<(Struct<'gcc>, TyAndLayout<'tcx>)>) -> Type<'gcc> {
+    match layout.abi {
+        Abi::Scalar(_) => bug!("handled elsewhere"),
+        Abi::Vector { ref element, count } => {
+            let element = layout.scalar_gcc_type_at(cx, element, Size::ZERO);
+            return cx.context.new_vector_type(element, count);
+        },
+        Abi::ScalarPair(..) => {
+            return cx.type_struct(
+                &[
+                    layout.scalar_pair_element_gcc_type(cx, 0, false),
+                    layout.scalar_pair_element_gcc_type(cx, 1, false),
+                ],
+                false,
+            );
+        }
+        Abi::Uninhabited | Abi::Aggregate { .. } => {}
+    }
+
+    let name = match layout.ty.kind() {
+        // FIXME(eddyb) producing readable type names for trait objects can result
+        // in problematically distinct types due to HRTB and subtyping (see #47638).
+        // ty::Dynamic(..) |
+        ty::Adt(..) | ty::Closure(..) | ty::Foreign(..) | ty::Generator(..) | ty::Str
+            if !cx.sess().fewer_names() =>
+        {
+            let mut name = with_no_trimmed_paths(|| layout.ty.to_string());
+            if let (&ty::Adt(def, _), &Variants::Single { index }) =
+                (layout.ty.kind(), &layout.variants)
+            {
+                if def.is_enum() && !def.variants.is_empty() {
+                    write!(&mut name, "::{}", def.variants[index].ident).unwrap();
+                }
+            }
+            if let (&ty::Generator(_, _, _), &Variants::Single { index }) =
+                (layout.ty.kind(), &layout.variants)
+            {
+                write!(&mut name, "::{}", ty::GeneratorSubsts::variant_name(index)).unwrap();
+            }
+            Some(name)
+        }
+        ty::Adt(..) => {
+            // If `Some` is returned then a named struct is created in LLVM. Name collisions are
+            // avoided by LLVM (with increasing suffixes). If rustc doesn't generate names then that
+            // can improve perf.
+            // FIXME(antoyo): I don't think that's true for libgccjit.
+            Some(String::new())
+        }
+        _ => None,
+    };
+
+    match layout.fields {
+        FieldsShape::Primitive | FieldsShape::Union(_) => {
+            let fill = cx.type_padding_filler(layout.size, layout.align.abi);
+            let packed = false;
+            match name {
+                None => cx.type_struct(&[fill], packed),
+                Some(ref name) => {
+                    let gcc_type = cx.type_named_struct(name);
+                    cx.set_struct_body(gcc_type, &[fill], packed);
+                    gcc_type.as_type()
+                },
+            }
+        }
+        FieldsShape::Array { count, .. } => cx.type_array(layout.field(cx, 0).gcc_type(cx, true), count),
+        FieldsShape::Arbitrary { .. } =>
+            match name {
+                None => {
+                    let (gcc_fields, packed) = struct_fields(cx, layout);
+                    cx.type_struct(&gcc_fields, packed)
+                },
+                Some(ref name) => {
+                    let gcc_type = cx.type_named_struct(name);
+                    *defer = Some((gcc_type, layout));
+                    gcc_type.as_type()
+                },
+            },
+    }
+}
+
+pub trait LayoutGccExt<'tcx> {
+    fn is_gcc_immediate(&self) -> bool;
+    fn is_gcc_scalar_pair(&self) -> bool;
+    fn gcc_type<'gcc>(&self, cx: &CodegenCx<'gcc, 'tcx>, set_fields: bool) -> Type<'gcc>;
+    fn immediate_gcc_type<'gcc>(&self, cx: &CodegenCx<'gcc, 'tcx>) -> Type<'gcc>;
+    fn scalar_gcc_type_at<'gcc>(&self, cx: &CodegenCx<'gcc, 'tcx>, scalar: &abi::Scalar, offset: Size) -> Type<'gcc>;
+    fn scalar_pair_element_gcc_type<'gcc>(&self, cx: &CodegenCx<'gcc, 'tcx>, index: usize, immediate: bool) -> Type<'gcc>;
+    fn gcc_field_index(&self, index: usize) -> u64;
+    fn pointee_info_at<'gcc>(&self, cx: &CodegenCx<'gcc, 'tcx>, offset: Size) -> Option<PointeeInfo>;
+}
+
+impl<'tcx> LayoutGccExt<'tcx> for TyAndLayout<'tcx> {
+    fn is_gcc_immediate(&self) -> bool {
+        match self.abi {
+            Abi::Scalar(_) | Abi::Vector { .. } => true,
+            Abi::ScalarPair(..) => false,
+            Abi::Uninhabited | Abi::Aggregate { .. } => self.is_zst(),
+        }
+    }
+
+    fn is_gcc_scalar_pair(&self) -> bool {
+        match self.abi {
+            Abi::ScalarPair(..) => true,
+            Abi::Uninhabited | Abi::Scalar(_) | Abi::Vector { .. } | Abi::Aggregate { .. } => false,
+        }
+    }
+
+    /// Gets the GCC type corresponding to a Rust type, i.e., `rustc_middle::ty::Ty`.
+    /// The pointee type of the pointer in `PlaceRef` is always this type.
+    /// For sized types, it is also the right LLVM type for an `alloca`
+    /// containing a value of that type, and most immediates (except `bool`).
+    /// Unsized types, however, are represented by a "minimal unit", e.g.
+    /// `[T]` becomes `T`, while `str` and `Trait` turn into `i8` - this
+    /// is useful for indexing slices, as `&[T]`'s data pointer is `T*`.
+    /// If the type is an unsized struct, the regular layout is generated,
+    /// with the inner-most trailing unsized field using the "minimal unit"
+    /// of that field's type - this is useful for taking the address of
+    /// that field and ensuring the struct has the right alignment.
+    //TODO(antoyo): do we still need the set_fields parameter?
+    fn gcc_type<'gcc>(&self, cx: &CodegenCx<'gcc, 'tcx>, set_fields: bool) -> Type<'gcc> {
+        if let Abi::Scalar(ref scalar) = self.abi {
+            // Use a different cache for scalars because pointers to DSTs
+            // can be either fat or thin (data pointers of fat pointers).
+            if let Some(&ty) = cx.scalar_types.borrow().get(&self.ty) {
+                return ty;
+            }
+            let ty =
+                match *self.ty.kind() {
+                    ty::Ref(_, ty, _) | ty::RawPtr(ty::TypeAndMut { ty, .. }) => {
+                        cx.type_ptr_to(cx.layout_of(ty).gcc_type(cx, set_fields))
+                    }
+                    ty::Adt(def, _) if def.is_box() => {
+                        cx.type_ptr_to(cx.layout_of(self.ty.boxed_ty()).gcc_type(cx, true))
+                    }
+                    ty::FnPtr(sig) => cx.fn_ptr_backend_type(&cx.fn_abi_of_fn_ptr(sig, ty::List::empty())),
+                    _ => self.scalar_gcc_type_at(cx, scalar, Size::ZERO),
+                };
+            cx.scalar_types.borrow_mut().insert(self.ty, ty);
+            return ty;
+        }
+
+        // Check the cache.
+        let variant_index =
+            match self.variants {
+                Variants::Single { index } => Some(index),
+                _ => None,
+            };
+        let cached_type = cx.types.borrow().get(&(self.ty, variant_index)).cloned();
+        if let Some(ty) = cached_type {
+            let type_to_set_fields = cx.types_with_fields_to_set.borrow_mut().remove(&ty);
+            if let Some((struct_type, layout)) = type_to_set_fields {
+                // Since we might be trying to generate a type containing another type which is not
+                // completely generated yet, we deferred setting the fields until now.
+                let (fields, packed) = struct_fields(cx, layout);
+                cx.set_struct_body(struct_type, &fields, packed);
+            }
+            return ty;
+        }
+
+        assert!(!self.ty.has_escaping_bound_vars(), "{:?} has escaping bound vars", self.ty);
+
+        // Make sure lifetimes are erased, to avoid generating distinct LLVM
+        // types for Rust types that only differ in the choice of lifetimes.
+        let normal_ty = cx.tcx.erase_regions(self.ty);
+
+        let mut defer = None;
+        let ty =
+            if self.ty != normal_ty {
+                let mut layout = cx.layout_of(normal_ty);
+                if let Some(v) = variant_index {
+                    layout = layout.for_variant(cx, v);
+                }
+                layout.gcc_type(cx, true)
+            }
+            else {
+                uncached_gcc_type(cx, *self, &mut defer)
+            };
+
+        cx.types.borrow_mut().insert((self.ty, variant_index), ty);
+
+        if let Some((ty, layout)) = defer {
+            let (fields, packed) = struct_fields(cx, layout);
+            cx.set_struct_body(ty, &fields, packed);
+        }
+
+        ty
+    }
+
+    fn immediate_gcc_type<'gcc>(&self, cx: &CodegenCx<'gcc, 'tcx>) -> Type<'gcc> {
+        if let Abi::Scalar(ref scalar) = self.abi {
+            if scalar.is_bool() {
+                return cx.type_i1();
+            }
+        }
+        self.gcc_type(cx, true)
+    }
+
+    fn scalar_gcc_type_at<'gcc>(&self, cx: &CodegenCx<'gcc, 'tcx>, scalar: &abi::Scalar, offset: Size) -> Type<'gcc> {
+        match scalar.value {
+            Int(i, true) => cx.type_from_integer(i),
+            Int(i, false) => cx.type_from_unsigned_integer(i),
+            F32 => cx.type_f32(),
+            F64 => cx.type_f64(),
+            Pointer => {
+                // If we know the alignment, pick something better than i8.
+                let pointee =
+                    if let Some(pointee) = self.pointee_info_at(cx, offset) {
+                        cx.type_pointee_for_align(pointee.align)
+                    }
+                    else {
+                        cx.type_i8()
+                    };
+                cx.type_ptr_to(pointee)
+            }
+        }
+    }
+
+    fn scalar_pair_element_gcc_type<'gcc>(&self, cx: &CodegenCx<'gcc, 'tcx>, index: usize, immediate: bool) -> Type<'gcc> {
+        // TODO(antoyo): remove llvm hack:
+        // HACK(eddyb) special-case fat pointers until LLVM removes
+        // pointee types, to avoid bitcasting every `OperandRef::deref`.
+        match self.ty.kind() {
+            ty::Ref(..) | ty::RawPtr(_) => {
+                return self.field(cx, index).gcc_type(cx, true);
+            }
+            ty::Adt(def, _) if def.is_box() => {
+                let ptr_ty = cx.tcx.mk_mut_ptr(self.ty.boxed_ty());
+                return cx.layout_of(ptr_ty).scalar_pair_element_gcc_type(cx, index, immediate);
+            }
+            _ => {}
+        }
+
+        let (a, b) = match self.abi {
+            Abi::ScalarPair(ref a, ref b) => (a, b),
+            _ => bug!("TyAndLayout::scalar_pair_element_llty({:?}): not applicable", self),
+        };
+        let scalar = [a, b][index];
+
+        // Make sure to return the same type `immediate_gcc_type` would when
+        // dealing with an immediate pair.  This means that `(bool, bool)` is
+        // effectively represented as `{i8, i8}` in memory and two `i1`s as an
+        // immediate, just like `bool` is typically `i8` in memory and only `i1`
+        // when immediate.  We need to load/store `bool` as `i8` to avoid
+        // crippling LLVM optimizations or triggering other LLVM bugs with `i1`.
+        // TODO(antoyo): this bugs certainly don't happen in this case since the bool type is used instead of i1.
+        if scalar.is_bool() {
+            return cx.type_i1();
+        }
+
+        let offset =
+            if index == 0 {
+                Size::ZERO
+            }
+            else {
+                a.value.size(cx).align_to(b.value.align(cx).abi)
+            };
+        self.scalar_gcc_type_at(cx, scalar, offset)
+    }
+
+    fn gcc_field_index(&self, index: usize) -> u64 {
+        match self.abi {
+            Abi::Scalar(_) | Abi::ScalarPair(..) => {
+                bug!("TyAndLayout::gcc_field_index({:?}): not applicable", self)
+            }
+            _ => {}
+        }
+        match self.fields {
+            FieldsShape::Primitive | FieldsShape::Union(_) => {
+                bug!("TyAndLayout::gcc_field_index({:?}): not applicable", self)
+            }
+
+            FieldsShape::Array { .. } => index as u64,
+
+            FieldsShape::Arbitrary { .. } => 1 + (self.fields.memory_index(index) as u64) * 2,
+        }
+    }
+
+    fn pointee_info_at<'a>(&self, cx: &CodegenCx<'a, 'tcx>, offset: Size) -> Option<PointeeInfo> {
+        if let Some(&pointee) = cx.pointee_infos.borrow().get(&(self.ty, offset)) {
+            return pointee;
+        }
+
+        let result = Ty::ty_and_layout_pointee_info_at(*self, cx, offset);
+
+        cx.pointee_infos.borrow_mut().insert((self.ty, offset), result);
+        result
+    }
+}
+
+impl<'gcc, 'tcx> LayoutTypeMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
+    fn backend_type(&self, layout: TyAndLayout<'tcx>) -> Type<'gcc> {
+        layout.gcc_type(self, true)
+    }
+
+    fn immediate_backend_type(&self, layout: TyAndLayout<'tcx>) -> Type<'gcc> {
+        layout.immediate_gcc_type(self)
+    }
+
+    fn is_backend_immediate(&self, layout: TyAndLayout<'tcx>) -> bool {
+        layout.is_gcc_immediate()
+    }
+
+    fn is_backend_scalar_pair(&self, layout: TyAndLayout<'tcx>) -> bool {
+        layout.is_gcc_scalar_pair()
+    }
+
+    fn backend_field_index(&self, layout: TyAndLayout<'tcx>, index: usize) -> u64 {
+        layout.gcc_field_index(index)
+    }
+
+    fn scalar_pair_element_backend_type(&self, layout: TyAndLayout<'tcx>, index: usize, immediate: bool) -> Type<'gcc> {
+        layout.scalar_pair_element_gcc_type(self, index, immediate)
+    }
+
+    fn cast_backend_type(&self, ty: &CastTarget) -> Type<'gcc> {
+        ty.gcc_type(self)
+    }
+
+    fn fn_ptr_backend_type(&self, fn_abi: &FnAbi<'tcx, Ty<'tcx>>) -> Type<'gcc> {
+        fn_abi.ptr_to_gcc_type(self)
+    }
+
+    fn reg_backend_type(&self, _ty: &Reg) -> Type<'gcc> {
+        unimplemented!();
+    }
+
+    fn fn_decl_backend_type(&self, _fn_abi: &FnAbi<'tcx, Ty<'tcx>>) -> Type<'gcc> {
+        // FIXME(antoyo): return correct type.
+        self.type_void()
+    }
+}
diff --git a/compiler/rustc_codegen_gcc/test.sh b/compiler/rustc_codegen_gcc/test.sh
new file mode 100755
index 00000000000..944d0ce516e
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/test.sh
@@ -0,0 +1,217 @@
+#!/bin/bash
+
+# TODO(antoyo): rewrite to cargo-make (or just) or something like that to only rebuild the sysroot when needed?
+
+set -e
+
+if [ -f ./gcc_path ]; then 
+    export GCC_PATH=$(cat gcc_path)
+else
+    echo 'Please put the path to your custom build of libgccjit in the file `gcc_path`, see Readme.md for details'
+    exit 1
+fi
+
+export LD_LIBRARY_PATH="$GCC_PATH"
+export LIBRARY_PATH="$GCC_PATH"
+
+if [[ "$1" == "--release" ]]; then
+    export CHANNEL='release'
+    CARGO_INCREMENTAL=1 cargo rustc --release
+    shift
+else
+    echo $LD_LIBRARY_PATH
+    export CHANNEL='debug'
+    cargo rustc
+fi
+
+source config.sh
+
+function clean() {
+    rm -r target/out || true
+    mkdir -p target/out/gccjit
+}
+
+function mini_tests() {
+    echo "[BUILD] mini_core"
+    $RUSTC example/mini_core.rs --crate-name mini_core --crate-type lib,dylib --target $TARGET_TRIPLE
+
+    echo "[BUILD] example"
+    $RUSTC example/example.rs --crate-type lib --target $TARGET_TRIPLE
+
+    echo "[AOT] mini_core_hello_world"
+    $RUSTC example/mini_core_hello_world.rs --crate-name mini_core_hello_world --crate-type bin -g --target $TARGET_TRIPLE
+    $RUN_WRAPPER ./target/out/mini_core_hello_world abc bcd
+}
+
+function build_sysroot() {
+    echo "[BUILD] sysroot"
+    time ./build_sysroot/build_sysroot.sh
+}
+
+function std_tests() {
+    echo "[AOT] arbitrary_self_types_pointers_and_wrappers"
+    $RUSTC example/arbitrary_self_types_pointers_and_wrappers.rs --crate-name arbitrary_self_types_pointers_and_wrappers --crate-type bin --target $TARGET_TRIPLE
+    $RUN_WRAPPER ./target/out/arbitrary_self_types_pointers_and_wrappers
+
+    echo "[AOT] alloc_system"
+    $RUSTC example/alloc_system.rs --crate-type lib --target "$TARGET_TRIPLE"
+
+    echo "[AOT] alloc_example"
+    $RUSTC example/alloc_example.rs --crate-type bin --target $TARGET_TRIPLE
+    $RUN_WRAPPER ./target/out/alloc_example
+
+    echo "[AOT] dst_field_align"
+    # FIXME(antoyo): Re-add -Zmir-opt-level=2 once rust-lang/rust#67529 is fixed.
+    $RUSTC example/dst-field-align.rs --crate-name dst_field_align --crate-type bin --target $TARGET_TRIPLE
+    $RUN_WRAPPER ./target/out/dst_field_align || (echo $?; false)
+
+    echo "[AOT] std_example"
+    $RUSTC example/std_example.rs --crate-type bin --target $TARGET_TRIPLE
+    $RUN_WRAPPER ./target/out/std_example --target $TARGET_TRIPLE
+
+    echo "[AOT] subslice-patterns-const-eval"
+    $RUSTC example/subslice-patterns-const-eval.rs --crate-type bin -Cpanic=abort --target $TARGET_TRIPLE
+    $RUN_WRAPPER ./target/out/subslice-patterns-const-eval
+
+    echo "[AOT] track-caller-attribute"
+    $RUSTC example/track-caller-attribute.rs --crate-type bin -Cpanic=abort --target $TARGET_TRIPLE
+    $RUN_WRAPPER ./target/out/track-caller-attribute
+
+    echo "[BUILD] mod_bench"
+    $RUSTC example/mod_bench.rs --crate-type bin --target $TARGET_TRIPLE
+}
+
+# FIXME(antoyo): linker gives multiple definitions error on Linux
+#echo "[BUILD] sysroot in release mode"
+#./build_sysroot/build_sysroot.sh --release
+
+# TODO(antoyo): uncomment when it works.
+#pushd simple-raytracer
+#if [[ "$HOST_TRIPLE" = "$TARGET_TRIPLE" ]]; then
+    #echo "[BENCH COMPILE] ebobby/simple-raytracer"
+    #hyperfine --runs ${RUN_RUNS:-10} --warmup 1 --prepare "rm -r target/*/debug || true" \
+    #"RUSTFLAGS='' cargo build --target $TARGET_TRIPLE" \
+    #"../cargo.sh build"
+
+    #echo "[BENCH RUN] ebobby/simple-raytracer"
+    #cp ./target/*/debug/main ./raytracer_cg_gccjit
+    #hyperfine --runs ${RUN_RUNS:-10} ./raytracer_cg_llvm ./raytracer_cg_gccjit
+#else
+    #echo "[BENCH COMPILE] ebobby/simple-raytracer (skipped)"
+    #echo "[COMPILE] ebobby/simple-raytracer"
+    #../cargo.sh build
+    #echo "[BENCH RUN] ebobby/simple-raytracer (skipped)"
+#fi
+#popd
+
+function test_libcore() {
+    pushd build_sysroot/sysroot_src/library/core/tests
+    echo "[TEST] libcore"
+    rm -r ./target || true
+    ../../../../../cargo.sh test
+    popd
+}
+
+# TODO(antoyo): uncomment when it works.
+#pushd regex
+#echo "[TEST] rust-lang/regex example shootout-regex-dna"
+#../cargo.sh clean
+## Make sure `[codegen mono items] start` doesn't poison the diff
+#../cargo.sh build --example shootout-regex-dna
+#cat examples/regexdna-input.txt | ../cargo.sh run --example shootout-regex-dna | grep -v "Spawned thread" > res.txt
+#diff -u res.txt examples/regexdna-output.txt
+
+#echo "[TEST] rust-lang/regex tests"
+#../cargo.sh test --tests -- --exclude-should-panic --test-threads 1 -Zunstable-options
+#popd
+
+#echo
+#echo "[BENCH COMPILE] mod_bench"
+
+#COMPILE_MOD_BENCH_INLINE="$RUSTC example/mod_bench.rs --crate-type bin -Zmir-opt-level=3 -O --crate-name mod_bench_inline"
+#COMPILE_MOD_BENCH_LLVM_0="rustc example/mod_bench.rs --crate-type bin -Copt-level=0 -o target/out/mod_bench_llvm_0 -Cpanic=abort"
+#COMPILE_MOD_BENCH_LLVM_1="rustc example/mod_bench.rs --crate-type bin -Copt-level=1 -o target/out/mod_bench_llvm_1 -Cpanic=abort"
+#COMPILE_MOD_BENCH_LLVM_2="rustc example/mod_bench.rs --crate-type bin -Copt-level=2 -o target/out/mod_bench_llvm_2 -Cpanic=abort"
+#COMPILE_MOD_BENCH_LLVM_3="rustc example/mod_bench.rs --crate-type bin -Copt-level=3 -o target/out/mod_bench_llvm_3 -Cpanic=abort"
+
+## Use 100 runs, because a single compilations doesn't take more than ~150ms, so it isn't very slow
+#hyperfine --runs ${COMPILE_RUNS:-100} "$COMPILE_MOD_BENCH_INLINE" "$COMPILE_MOD_BENCH_LLVM_0" "$COMPILE_MOD_BENCH_LLVM_1" "$COMPILE_MOD_BENCH_LLVM_2" "$COMPILE_MOD_BENCH_LLVM_3"
+
+#echo
+#echo "[BENCH RUN] mod_bench"
+#hyperfine --runs ${RUN_RUNS:-10} ./target/out/mod_bench{,_inline} ./target/out/mod_bench_llvm_*
+
+function test_rustc() {
+    echo
+    echo "[TEST] rust-lang/rust"
+
+    rust_toolchain=$(cat rust-toolchain)
+
+    git clone https://github.com/rust-lang/rust.git || true
+    cd rust
+    git fetch
+    git checkout $(rustc -V | cut -d' ' -f3 | tr -d '(')
+    export RUSTFLAGS=
+
+    rm config.toml || true
+
+    cat > config.toml <<EOF
+[rust]
+codegen-backends = []
+deny-warnings = false
+
+[build]
+cargo = "$(which cargo)"
+local-rebuild = true
+rustc = "$HOME/.rustup/toolchains/$rust_toolchain-$TARGET_TRIPLE/bin/rustc"
+EOF
+
+    rustc -V | cut -d' ' -f3 | tr -d '('
+    git checkout $(rustc -V | cut -d' ' -f3 | tr -d '(') src/test
+
+    for test in $(rg -i --files-with-matches "//(\[\w+\])?~|// error-pattern:|// build-fail|// run-fail|-Cllvm-args" src/test/ui); do
+      rm $test
+    done
+
+    git checkout -- src/test/ui/issues/auxiliary/issue-3136-a.rs # contains //~ERROR, but shouldn't be removed
+
+    rm -r src/test/ui/{abi*,extern/,llvm-asm/,panic-runtime/,panics/,unsized-locals/,proc-macro/,threads-sendsync/,thinlto/,simd*,borrowck/,test*,*lto*.rs} || true
+    for test in $(rg --files-with-matches "catch_unwind|should_panic|thread|lto" src/test/ui); do
+      rm $test
+    done
+    git checkout src/test/ui/type-alias-impl-trait/auxiliary/cross_crate_ice.rs
+    git checkout src/test/ui/type-alias-impl-trait/auxiliary/cross_crate_ice2.rs
+    rm src/test/ui/llvm-asm/llvm-asm-in-out-operand.rs || true # TODO(antoyo): Enable back this test if I ever implement the llvm_asm! macro.
+
+    RUSTC_ARGS="-Zpanic-abort-tests -Zsymbol-mangling-version=v0 -Zcodegen-backend="$(pwd)"/../target/"$CHANNEL"/librustc_codegen_gcc."$dylib_ext" --sysroot "$(pwd)"/../build_sysroot/sysroot -Cpanic=abort"
+
+    echo "[TEST] rustc test suite"
+    COMPILETEST_FORCE_STAGE0=1 ./x.py test --run always --stage 0 src/test/ui/ --rustc-args "$RUSTC_ARGS"
+}
+
+function clean_ui_tests() {
+    find rust/build/x86_64-unknown-linux-gnu/test/ui/ -name stamp -exec rm -rf {} \;
+}
+
+case $1 in
+    "--test-rustc")
+        test_rustc
+        ;;
+
+    "--test-libcore")
+        test_libcore
+        ;;
+
+    "--clean-ui-tests")
+        clean_ui_tests
+        ;;
+
+    *)
+        clean
+        mini_tests
+        build_sysroot
+        std_tests
+        test_libcore
+        test_rustc
+        ;;
+esac
diff --git a/compiler/rustc_codegen_gcc/tests/lib.rs b/compiler/rustc_codegen_gcc/tests/lib.rs
new file mode 100644
index 00000000000..8ee35b30bc8
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/lib.rs
@@ -0,0 +1,50 @@
+use std::{
+    env::{self, current_dir},
+    path::PathBuf,
+    process::Command,
+};
+
+use lang_tester::LangTester;
+use tempfile::TempDir;
+
+fn main() {
+    let tempdir = TempDir::new().expect("temp dir");
+    let current_dir = current_dir().expect("current dir");
+    let current_dir = current_dir.to_str().expect("current dir").to_string();
+    let gcc_path = include_str!("../gcc_path");
+    let gcc_path = gcc_path.trim();
+    env::set_var("LD_LIBRARY_PATH", gcc_path);
+    LangTester::new()
+        .test_dir("tests/run")
+        .test_file_filter(|path| path.extension().expect("extension").to_str().expect("to_str") == "rs")
+        .test_extract(|source| {
+            let lines =
+                source.lines()
+                    .skip_while(|l| !l.starts_with("//"))
+                    .take_while(|l| l.starts_with("//"))
+                    .map(|l| &l[2..])
+                    .collect::<Vec<_>>()
+                    .join("\n");
+            Some(lines)
+        })
+        .test_cmds(move |path| {
+            // Test command 1: Compile `x.rs` into `tempdir/x`.
+            let mut exe = PathBuf::new();
+            exe.push(&tempdir);
+            exe.push(path.file_stem().expect("file_stem"));
+            let mut compiler = Command::new("rustc");
+            compiler.args(&[
+                &format!("-Zcodegen-backend={}/target/debug/librustc_codegen_gcc.so", current_dir),
+                "--sysroot", &format!("{}/build_sysroot/sysroot/", current_dir),
+                "-Zno-parallel-llvm",
+                "-C", "panic=abort",
+                "-C", "link-arg=-lc",
+                "-o", exe.to_str().expect("to_str"),
+                path.to_str().expect("to_str"),
+            ]);
+            // Test command 2: run `tempdir/x`.
+            let runtime = Command::new(exe);
+            vec![("Compiler", compiler), ("Run-time", runtime)]
+        })
+        .run();
+}
diff --git a/compiler/rustc_codegen_gcc/tests/run/abort1.rs b/compiler/rustc_codegen_gcc/tests/run/abort1.rs
new file mode 100644
index 00000000000..291af5993aa
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/run/abort1.rs
@@ -0,0 +1,51 @@
+// Compiler:
+//
+// Run-time:
+//   status: signal
+
+#![feature(auto_traits, lang_items, no_core, start, intrinsics)]
+
+#![no_std]
+#![no_core]
+
+/*
+ * Core
+ */
+
+// Because we don't have core yet.
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "copy"]
+trait Copy {
+}
+
+impl Copy for isize {}
+
+#[lang = "receiver"]
+trait Receiver {
+}
+
+#[lang = "freeze"]
+pub(crate) unsafe auto trait Freeze {}
+
+mod intrinsics {
+    use super::Sized;
+
+    extern "rust-intrinsic" {
+        pub fn abort() -> !;
+    }
+}
+
+/*
+ * Code
+ */
+
+fn test_fail() -> ! {
+    unsafe { intrinsics::abort() };
+}
+
+#[start]
+fn main(mut argc: isize, _argv: *const *const u8) -> isize {
+    test_fail();
+}
diff --git a/compiler/rustc_codegen_gcc/tests/run/abort2.rs b/compiler/rustc_codegen_gcc/tests/run/abort2.rs
new file mode 100644
index 00000000000..3c87c567892
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/run/abort2.rs
@@ -0,0 +1,53 @@
+// Compiler:
+//
+// Run-time:
+//   status: signal
+
+#![feature(auto_traits, lang_items, no_core, start, intrinsics)]
+
+#![no_std]
+#![no_core]
+
+/*
+ * Core
+ */
+
+// Because we don't have core yet.
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "copy"]
+trait Copy {
+}
+
+impl Copy for isize {}
+
+#[lang = "receiver"]
+trait Receiver {
+}
+
+#[lang = "freeze"]
+pub(crate) unsafe auto trait Freeze {}
+
+mod intrinsics {
+    use super::Sized;
+
+    extern "rust-intrinsic" {
+        pub fn abort() -> !;
+    }
+}
+
+/*
+ * Code
+ */
+
+fn fail() -> i32 {
+    unsafe { intrinsics::abort() };
+    0
+}
+
+#[start]
+fn main(mut argc: isize, _argv: *const *const u8) -> isize {
+    fail();
+    0
+}
diff --git a/compiler/rustc_codegen_gcc/tests/run/array.rs b/compiler/rustc_codegen_gcc/tests/run/array.rs
new file mode 100644
index 00000000000..8b621d8a353
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/run/array.rs
@@ -0,0 +1,229 @@
+// Compiler:
+//
+// Run-time:
+//   status: 0
+//   stdout: 42
+//     7
+//     5
+//     10
+
+#![feature(arbitrary_self_types, auto_traits, lang_items, no_core, start, intrinsics)]
+
+#![no_std]
+#![no_core]
+
+/*
+ * Core
+ */
+
+// Because we don't have core yet.
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "copy"]
+trait Copy {
+}
+
+impl Copy for isize {}
+impl Copy for usize {}
+impl Copy for i32 {}
+impl Copy for u8 {}
+impl Copy for i8 {}
+impl Copy for i16 {}
+
+#[lang = "receiver"]
+trait Receiver {
+}
+
+#[lang = "freeze"]
+pub(crate) unsafe auto trait Freeze {}
+
+mod libc {
+    #[link(name = "c")]
+    extern "C" {
+        pub fn printf(format: *const i8, ...) -> i32;
+        pub fn puts(s: *const u8) -> i32;
+    }
+}
+
+#[lang = "index"]
+pub trait Index<Idx: ?Sized> {
+    type Output: ?Sized;
+    fn index(&self, index: Idx) -> &Self::Output;
+}
+
+impl<T> Index<usize> for [T; 3] {
+    type Output = T;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        &self[index]
+    }
+}
+
+impl<T> Index<usize> for [T] {
+    type Output = T;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        &self[index]
+    }
+}
+
+#[lang = "drop_in_place"]
+#[allow(unconditional_recursion)]
+pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
+    // Code here does not matter - this is replaced by the
+    // real drop glue by the compiler.
+    drop_in_place(to_drop);
+}
+
+#[lang = "panic"]
+#[track_caller]
+#[no_mangle]
+pub fn panic(_msg: &str) -> ! {
+    unsafe {
+        libc::puts("Panicking\0" as *const str as *const u8);
+        intrinsics::abort();
+    }
+}
+
+#[lang = "panic_location"]
+struct PanicLocation {
+    file: &'static str,
+    line: u32,
+    column: u32,
+}
+
+#[lang = "panic_bounds_check"]
+#[track_caller]
+#[no_mangle]
+fn panic_bounds_check(index: usize, len: usize) -> ! {
+    unsafe {
+        libc::printf("index out of bounds: the len is %d but the index is %d\n\0" as *const str as *const i8, len, index);
+        intrinsics::abort();
+    }
+}
+
+mod intrinsics {
+    extern "rust-intrinsic" {
+        pub fn abort() -> !;
+    }
+}
+
+#[lang = "add"]
+trait Add<RHS = Self> {
+    type Output;
+
+    fn add(self, rhs: RHS) -> Self::Output;
+}
+
+impl Add for u8 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for i8 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for i32 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for usize {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for isize {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+#[lang = "sub"]
+pub trait Sub<RHS = Self> {
+    type Output;
+
+    fn sub(self, rhs: RHS) -> Self::Output;
+}
+
+impl Sub for usize {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for isize {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for u8 {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for i8 {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for i16 {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+
+/*
+ * Code
+ */
+
+static mut ONE: usize = 1;
+
+fn make_array() -> [u8; 3] {
+    [42, 10, 5]
+}
+
+#[start]
+fn main(argc: isize, _argv: *const *const u8) -> isize {
+    let array = [42, 7, 5];
+    let array2 = make_array();
+    unsafe {
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, array[ONE - 1]);
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, array[ONE]);
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, array[ONE + 1]);
+
+        libc::printf(b"%d\n\0" as *const u8 as *const i8, array2[argc as usize] as u32);
+    }
+    0
+}
diff --git a/compiler/rustc_codegen_gcc/tests/run/asm.rs b/compiler/rustc_codegen_gcc/tests/run/asm.rs
new file mode 100644
index 00000000000..9c0055b0b6b
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/run/asm.rs
@@ -0,0 +1,153 @@
+// Compiler:
+//
+// Run-time:
+//   status: 0
+
+#![feature(asm, global_asm)]
+
+global_asm!("
+    .global add_asm
+add_asm:
+     mov rax, rdi
+     add rax, rsi
+     ret"
+);
+
+extern "C" {
+    fn add_asm(a: i64, b: i64) -> i64;
+}
+
+fn main() {
+    unsafe {
+        asm!("nop");
+    }
+
+    let x: u64;
+    unsafe {
+        asm!("mov $5, {}",
+            out(reg) x,
+            options(att_syntax)
+        );
+    }
+    assert_eq!(x, 5);
+
+    let x: u64;
+    let input: u64 = 42;
+    unsafe {
+        asm!("mov {input}, {output}",
+             "add $1, {output}",
+            input = in(reg) input,
+            output = out(reg) x,
+            options(att_syntax)
+        );
+    }
+    assert_eq!(x, 43);
+
+    let x: u64;
+    unsafe {
+        asm!("mov {}, 6",
+            out(reg) x,
+        );
+    }
+    assert_eq!(x, 6);
+
+    let x: u64;
+    let input: u64 = 42;
+    unsafe {
+        asm!("mov {output}, {input}",
+             "add {output}, 1",
+            input = in(reg) input,
+            output = out(reg) x,
+        );
+    }
+    assert_eq!(x, 43);
+
+    // check inout(reg_class) x 
+    let mut x: u64 = 42;
+    unsafe {
+        asm!("add {0}, {0}",
+            inout(reg) x 
+        );
+    }
+    assert_eq!(x, 84);
+
+    // check inout("reg") x
+    let mut x: u64 = 42;
+    unsafe {
+        asm!("add r11, r11",
+            inout("r11") x 
+        );
+    }
+    assert_eq!(x, 84);
+
+    // check a mix of
+    // in("reg")
+    // inout(class) x => y
+    // inout (class) x
+    let x: u64 = 702;
+    let y: u64 = 100;
+    let res: u64;
+    let mut rem: u64 = 0;
+    unsafe {
+        asm!("div r11",
+            in("r11") y,
+            inout("eax") x => res,
+            inout("edx") rem,
+        );
+    }
+    assert_eq!(res, 7);
+    assert_eq!(rem, 2);
+
+    // check const 
+    let mut x: u64 = 42;
+    unsafe {
+        asm!("add {}, {}",
+            inout(reg) x,
+            const 1 
+        );
+    }
+    assert_eq!(x, 43);
+
+    // check const (ATT syntax)
+    let mut x: u64 = 42;
+    unsafe {
+        asm!("add {}, {}",
+            const 1,
+            inout(reg) x,
+            options(att_syntax)
+        );
+    }
+    assert_eq!(x, 43);
+
+    // check sym fn
+    extern "C" fn foo() -> u64 { 42 }
+    let x: u64;
+    unsafe {
+        asm!("call {}", sym foo, lateout("rax") x);
+    }
+    assert_eq!(x, 42);
+
+    // check sym fn (ATT syntax)
+    let x: u64;
+    unsafe {
+        asm!("call {}", sym foo, lateout("rax") x, options(att_syntax));
+    }
+    assert_eq!(x, 42);
+
+    // check sym static
+    static FOO: u64 = 42;
+    let x: u64;
+    unsafe {
+        asm!("mov {1}, qword ptr [rip + {0}]", sym FOO, lateout(reg) x);
+    }
+    assert_eq!(x, 42);
+
+    // check sym static (ATT syntax)
+    let x: u64;
+    unsafe {
+        asm!("movq {0}(%rip), {1}", sym FOO, lateout(reg) x, options(att_syntax));
+    }
+    assert_eq!(x, 42);
+
+    assert_eq!(unsafe { add_asm(40, 2) }, 42);
+}
diff --git a/compiler/rustc_codegen_gcc/tests/run/assign.rs b/compiler/rustc_codegen_gcc/tests/run/assign.rs
new file mode 100644
index 00000000000..cc8647006ca
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/run/assign.rs
@@ -0,0 +1,153 @@
+// Compiler:
+//
+// Run-time:
+//   stdout: 2
+//     7 8
+//     10
+
+#![allow(unused_attributes)]
+#![feature(auto_traits, lang_items, no_core, start, intrinsics, track_caller)]
+
+#![no_std]
+#![no_core]
+
+/*
+ * Core
+ */
+
+// Because we don't have core yet.
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "copy"]
+trait Copy {
+}
+
+impl Copy for isize {}
+impl Copy for *mut i32 {}
+impl Copy for usize {}
+impl Copy for u8 {}
+impl Copy for i8 {}
+impl Copy for i32 {}
+
+#[lang = "receiver"]
+trait Receiver {
+}
+
+#[lang = "freeze"]
+pub(crate) unsafe auto trait Freeze {}
+
+#[lang = "panic_location"]
+struct PanicLocation {
+    file: &'static str,
+    line: u32,
+    column: u32,
+}
+
+mod libc {
+    #[link(name = "c")]
+    extern "C" {
+        pub fn puts(s: *const u8) -> i32;
+        pub fn fflush(stream: *mut i32) -> i32;
+        pub fn printf(format: *const i8, ...) -> i32;
+
+        pub static STDOUT: *mut i32;
+    }
+}
+
+mod intrinsics {
+    extern "rust-intrinsic" {
+        pub fn abort() -> !;
+    }
+}
+
+#[lang = "panic"]
+#[track_caller]
+#[no_mangle]
+pub fn panic(_msg: &str) -> ! {
+    unsafe {
+        libc::puts("Panicking\0" as *const str as *const u8);
+        libc::fflush(libc::STDOUT);
+        intrinsics::abort();
+    }
+}
+
+#[lang = "add"]
+trait Add<RHS = Self> {
+    type Output;
+
+    fn add(self, rhs: RHS) -> Self::Output;
+}
+
+impl Add for u8 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for i8 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for i32 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for usize {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for isize {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+/*
+ * Code
+ */
+
+fn inc_ref(num: &mut isize) -> isize {
+    *num = *num + 5;
+    *num + 1
+}
+
+fn inc(num: isize) -> isize {
+    num + 1
+}
+
+
+#[start]
+fn main(mut argc: isize, _argv: *const *const u8) -> isize {
+    argc = inc(argc);
+    unsafe {
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, argc);
+    }
+
+    let b = inc_ref(&mut argc);
+    unsafe {
+        libc::printf(b"%ld %ld\n\0" as *const u8 as *const i8, argc, b);
+    }
+
+    argc = 10;
+    unsafe {
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, argc);
+    }
+    0
+}
diff --git a/compiler/rustc_codegen_gcc/tests/run/closure.rs b/compiler/rustc_codegen_gcc/tests/run/closure.rs
new file mode 100644
index 00000000000..7121a5f0d52
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/run/closure.rs
@@ -0,0 +1,230 @@
+// Compiler:
+//
+// Run-time:
+//   status: 0
+//   stdout: Arg: 1
+//     Argument: 1
+//     String arg: 1
+//     Int argument: 2
+//     Both args: 11
+
+#![feature(arbitrary_self_types, auto_traits, lang_items, no_core, start, intrinsics,
+    unboxed_closures)]
+
+#![no_std]
+#![no_core]
+
+/*
+ * Core
+ */
+
+// Because we don't have core yet.
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "copy"]
+trait Copy {
+}
+
+impl Copy for isize {}
+impl Copy for usize {}
+impl Copy for i32 {}
+impl Copy for u32 {}
+impl Copy for u8 {}
+impl Copy for i8 {}
+
+#[lang = "receiver"]
+trait Receiver {
+}
+
+#[lang = "freeze"]
+pub(crate) unsafe auto trait Freeze {}
+
+mod libc {
+    #[link(name = "c")]
+    extern "C" {
+        pub fn puts(s: *const u8) -> i32;
+        pub fn printf(format: *const i8, ...) -> i32;
+    }
+}
+
+#[lang = "index"]
+pub trait Index<Idx: ?Sized> {
+    type Output: ?Sized;
+    fn index(&self, index: Idx) -> &Self::Output;
+}
+
+impl<T> Index<usize> for [T; 3] {
+    type Output = T;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        &self[index]
+    }
+}
+
+impl<T> Index<usize> for [T] {
+    type Output = T;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        &self[index]
+    }
+}
+
+#[lang = "drop_in_place"]
+#[allow(unconditional_recursion)]
+pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
+    // Code here does not matter - this is replaced by the
+    // real drop glue by the compiler.
+    drop_in_place(to_drop);
+}
+
+#[lang = "panic_location"]
+struct PanicLocation {
+    file: &'static str,
+    line: u32,
+    column: u32,
+}
+
+#[lang = "panic_bounds_check"]
+#[track_caller]
+#[no_mangle]
+fn panic_bounds_check(index: usize, len: usize) -> ! {
+    unsafe {
+        libc::printf("index out of bounds: the len is %d but the index is %d\n\0" as *const str as *const i8, len, index);
+        intrinsics::abort();
+    }
+}
+
+mod intrinsics {
+    extern "rust-intrinsic" {
+        pub fn abort() -> !;
+    }
+}
+
+#[lang = "unsize"]
+pub trait Unsize<T: ?Sized> {}
+
+#[lang = "coerce_unsized"]
+pub trait CoerceUnsized<T> {}
+
+impl<'a, 'b: 'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<&'a U> for &'b T {}
+impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<&'a mut U> for &'a mut T {}
+impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for *const T {}
+impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*mut U> for *mut T {}
+
+#[lang = "fn_once"]
+#[rustc_paren_sugar]
+pub trait FnOnce<Args> {
+    #[lang = "fn_once_output"]
+    type Output;
+
+    extern "rust-call" fn call_once(self, args: Args) -> Self::Output;
+}
+
+#[lang = "fn_mut"]
+#[rustc_paren_sugar]
+pub trait FnMut<Args>: FnOnce<Args> {
+    extern "rust-call" fn call_mut(&mut self, args: Args) -> Self::Output;
+}
+
+#[lang = "add"]
+trait Add<RHS = Self> {
+    type Output;
+
+    fn add(self, rhs: RHS) -> Self::Output;
+}
+
+impl Add for u8 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for i8 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for i32 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for usize {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for isize {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+#[lang = "panic"]
+#[track_caller]
+#[no_mangle]
+pub fn panic(_msg: &str) -> ! {
+    unsafe {
+        libc::puts("Panicking\0" as *const str as *const u8);
+        intrinsics::abort();
+    }
+}
+
+/*
+ * Code
+ */
+
+#[start]
+fn main(mut argc: isize, _argv: *const *const u8) -> isize {
+    let string = "Arg: %d\n\0";
+    let mut closure = || {
+        unsafe {
+            libc::printf(string as *const str as *const i8, argc);
+        }
+    };
+    closure();
+
+    let mut closure = || {
+        unsafe {
+            libc::printf("Argument: %d\n\0" as *const str as *const i8, argc);
+        }
+    };
+    closure();
+
+    let mut closure = |string| {
+        unsafe {
+            libc::printf(string as *const str as *const i8, argc);
+        }
+    };
+    closure("String arg: %d\n\0");
+
+    let mut closure = |arg: isize| {
+        unsafe {
+            libc::printf("Int argument: %d\n\0" as *const str as *const i8, arg);
+        }
+    };
+    closure(argc + 1);
+
+    let mut closure = |string, arg: isize| {
+        unsafe {
+            libc::printf(string as *const str as *const i8, arg);
+        }
+    };
+    closure("Both args: %d\n\0", argc + 10);
+
+    0
+}
diff --git a/compiler/rustc_codegen_gcc/tests/run/condition.rs b/compiler/rustc_codegen_gcc/tests/run/condition.rs
new file mode 100644
index 00000000000..6a2e2d5bb11
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/run/condition.rs
@@ -0,0 +1,320 @@
+// Compiler:
+//
+// Run-time:
+//   status: 0
+//   stdout: true
+//     1
+
+#![feature(arbitrary_self_types, auto_traits, lang_items, no_core, start, intrinsics)]
+
+#![no_std]
+#![no_core]
+
+/*
+ * Core
+ */
+
+// Because we don't have core yet.
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "copy"]
+trait Copy {
+}
+
+impl Copy for isize {}
+impl Copy for usize {}
+impl Copy for u64 {}
+impl Copy for i32 {}
+impl Copy for u32 {}
+impl Copy for bool {}
+impl Copy for u16 {}
+impl Copy for i16 {}
+impl Copy for char {}
+impl Copy for i8 {}
+impl Copy for u8 {}
+
+#[lang = "receiver"]
+trait Receiver {
+}
+
+#[lang = "freeze"]
+pub(crate) unsafe auto trait Freeze {}
+
+mod libc {
+    #[link(name = "c")]
+    extern "C" {
+        pub fn printf(format: *const i8, ...) -> i32;
+        pub fn puts(s: *const u8) -> i32;
+    }
+}
+
+#[lang = "index"]
+pub trait Index<Idx: ?Sized> {
+    type Output: ?Sized;
+    fn index(&self, index: Idx) -> &Self::Output;
+}
+
+impl<T> Index<usize> for [T; 3] {
+    type Output = T;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        &self[index]
+    }
+}
+
+impl<T> Index<usize> for [T] {
+    type Output = T;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        &self[index]
+    }
+}
+
+#[lang = "drop_in_place"]
+#[allow(unconditional_recursion)]
+pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
+    // Code here does not matter - this is replaced by the
+    // real drop glue by the compiler.
+    drop_in_place(to_drop);
+}
+
+#[lang = "panic"]
+#[track_caller]
+#[no_mangle]
+pub fn panic(_msg: &str) -> ! {
+    unsafe {
+        libc::puts("Panicking\0" as *const str as *const u8);
+        intrinsics::abort();
+    }
+}
+
+#[lang = "panic_location"]
+struct PanicLocation {
+    file: &'static str,
+    line: u32,
+    column: u32,
+}
+
+#[lang = "panic_bounds_check"]
+#[track_caller]
+#[no_mangle]
+fn panic_bounds_check(index: usize, len: usize) -> ! {
+    unsafe {
+        libc::printf("index out of bounds: the len is %d but the index is %d\n\0" as *const str as *const i8, len, index);
+        intrinsics::abort();
+    }
+}
+
+mod intrinsics {
+    extern "rust-intrinsic" {
+        pub fn abort() -> !;
+    }
+}
+
+#[lang = "add"]
+trait Add<RHS = Self> {
+    type Output;
+
+    fn add(self, rhs: RHS) -> Self::Output;
+}
+
+impl Add for u8 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for i8 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for i32 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for usize {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for isize {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+#[lang = "sub"]
+pub trait Sub<RHS = Self> {
+    type Output;
+
+    fn sub(self, rhs: RHS) -> Self::Output;
+}
+
+impl Sub for usize {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for isize {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for u8 {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for i8 {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for i16 {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+#[lang = "eq"]
+pub trait PartialEq<Rhs: ?Sized = Self> {
+    fn eq(&self, other: &Rhs) -> bool;
+    fn ne(&self, other: &Rhs) -> bool;
+}
+
+impl PartialEq for u8 {
+    fn eq(&self, other: &u8) -> bool {
+        (*self) == (*other)
+    }
+    fn ne(&self, other: &u8) -> bool {
+        (*self) != (*other)
+    }
+}
+
+impl PartialEq for u16 {
+    fn eq(&self, other: &u16) -> bool {
+        (*self) == (*other)
+    }
+    fn ne(&self, other: &u16) -> bool {
+        (*self) != (*other)
+    }
+}
+
+impl PartialEq for u32 {
+    fn eq(&self, other: &u32) -> bool {
+        (*self) == (*other)
+    }
+    fn ne(&self, other: &u32) -> bool {
+        (*self) != (*other)
+    }
+}
+
+
+impl PartialEq for u64 {
+    fn eq(&self, other: &u64) -> bool {
+        (*self) == (*other)
+    }
+    fn ne(&self, other: &u64) -> bool {
+        (*self) != (*other)
+    }
+}
+
+impl PartialEq for usize {
+    fn eq(&self, other: &usize) -> bool {
+        (*self) == (*other)
+    }
+    fn ne(&self, other: &usize) -> bool {
+        (*self) != (*other)
+    }
+}
+
+impl PartialEq for i8 {
+    fn eq(&self, other: &i8) -> bool {
+        (*self) == (*other)
+    }
+    fn ne(&self, other: &i8) -> bool {
+        (*self) != (*other)
+    }
+}
+
+impl PartialEq for i32 {
+    fn eq(&self, other: &i32) -> bool {
+        (*self) == (*other)
+    }
+    fn ne(&self, other: &i32) -> bool {
+        (*self) != (*other)
+    }
+}
+
+impl PartialEq for isize {
+    fn eq(&self, other: &isize) -> bool {
+        (*self) == (*other)
+    }
+    fn ne(&self, other: &isize) -> bool {
+        (*self) != (*other)
+    }
+}
+
+impl PartialEq for char {
+    fn eq(&self, other: &char) -> bool {
+        (*self) == (*other)
+    }
+    fn ne(&self, other: &char) -> bool {
+        (*self) != (*other)
+    }
+}
+
+/*
+ * Code
+ */
+
+#[start]
+fn main(argc: isize, _argv: *const *const u8) -> isize {
+    unsafe {
+        if argc == 1 {
+            libc::printf(b"true\n\0" as *const u8 as *const i8);
+        }
+
+        let string =
+            match argc {
+                1 => b"1\n\0",
+                2 => b"2\n\0",
+                3 => b"3\n\0",
+                4 => b"4\n\0",
+                5 => b"5\n\0",
+                _ => b"_\n\0",
+            };
+        libc::printf(string as *const u8 as *const i8);
+    }
+    0
+}
diff --git a/compiler/rustc_codegen_gcc/tests/run/empty_main.rs b/compiler/rustc_codegen_gcc/tests/run/empty_main.rs
new file mode 100644
index 00000000000..c02cfd2a85f
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/run/empty_main.rs
@@ -0,0 +1,39 @@
+// Compiler:
+//
+// Run-time:
+//   status: 0
+
+#![feature(auto_traits, lang_items, no_core, start)]
+
+#![no_std]
+#![no_core]
+
+/*
+ * Core
+ */
+
+// Because we don't have core yet.
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "copy"]
+trait Copy {
+}
+
+impl Copy for isize {}
+
+#[lang = "receiver"]
+trait Receiver {
+}
+
+#[lang = "freeze"]
+pub(crate) unsafe auto trait Freeze {}
+
+/*
+ * Code
+ */
+
+#[start]
+fn main(mut argc: isize, _argv: *const *const u8) -> isize {
+    0
+}
diff --git a/compiler/rustc_codegen_gcc/tests/run/exit.rs b/compiler/rustc_codegen_gcc/tests/run/exit.rs
new file mode 100644
index 00000000000..956e53dd4aa
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/run/exit.rs
@@ -0,0 +1,49 @@
+// Compiler:
+//
+// Run-time:
+//   status: 2
+
+#![feature(auto_traits, lang_items, no_core, start, intrinsics)]
+
+#![no_std]
+#![no_core]
+
+mod libc {
+    #[link(name = "c")]
+    extern "C" {
+        pub fn exit(status: i32);
+    }
+}
+
+/*
+ * Core
+ */
+
+// Because we don't have core yet.
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "copy"]
+trait Copy {
+}
+
+impl Copy for isize {}
+
+#[lang = "receiver"]
+trait Receiver {
+}
+
+#[lang = "freeze"]
+pub(crate) unsafe auto trait Freeze {}
+
+/*
+ * Code
+ */
+
+#[start]
+fn main(mut argc: isize, _argv: *const *const u8) -> isize {
+    unsafe {
+        libc::exit(2);
+    }
+    0
+}
diff --git a/compiler/rustc_codegen_gcc/tests/run/exit_code.rs b/compiler/rustc_codegen_gcc/tests/run/exit_code.rs
new file mode 100644
index 00000000000..eeab3520951
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/run/exit_code.rs
@@ -0,0 +1,39 @@
+// Compiler:
+//
+// Run-time:
+//   status: 1
+
+#![feature(auto_traits, lang_items, no_core, start)]
+
+#![no_std]
+#![no_core]
+
+/*
+ * Core
+ */
+
+// Because we don't have core yet.
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "copy"]
+trait Copy {
+}
+
+impl Copy for isize {}
+
+#[lang = "receiver"]
+trait Receiver {
+}
+
+#[lang = "freeze"]
+pub(crate) unsafe auto trait Freeze {}
+
+/*
+ * Code
+ */
+
+#[start]
+fn main(mut argc: isize, _argv: *const *const u8) -> isize {
+    1
+}
diff --git a/compiler/rustc_codegen_gcc/tests/run/fun_ptr.rs b/compiler/rustc_codegen_gcc/tests/run/fun_ptr.rs
new file mode 100644
index 00000000000..a226fff79e5
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/run/fun_ptr.rs
@@ -0,0 +1,223 @@
+// Compiler:
+//
+// Run-time:
+//   status: 0
+//   stdout: 1
+
+#![feature(arbitrary_self_types, auto_traits, lang_items, no_core, start, intrinsics)]
+
+#![no_std]
+#![no_core]
+
+/*
+ * Core
+ */
+
+// Because we don't have core yet.
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "copy"]
+trait Copy {
+}
+
+impl Copy for isize {}
+impl Copy for usize {}
+impl Copy for i32 {}
+impl Copy for u8 {}
+impl Copy for i8 {}
+impl Copy for i16 {}
+
+#[lang = "receiver"]
+trait Receiver {
+}
+
+#[lang = "freeze"]
+pub(crate) unsafe auto trait Freeze {}
+
+mod libc {
+    #[link(name = "c")]
+    extern "C" {
+        pub fn printf(format: *const i8, ...) -> i32;
+        pub fn puts(s: *const u8) -> i32;
+    }
+}
+
+#[lang = "index"]
+pub trait Index<Idx: ?Sized> {
+    type Output: ?Sized;
+    fn index(&self, index: Idx) -> &Self::Output;
+}
+
+impl<T> Index<usize> for [T; 3] {
+    type Output = T;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        &self[index]
+    }
+}
+
+impl<T> Index<usize> for [T] {
+    type Output = T;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        &self[index]
+    }
+}
+
+#[lang = "drop_in_place"]
+#[allow(unconditional_recursion)]
+pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
+    // Code here does not matter - this is replaced by the
+    // real drop glue by the compiler.
+    drop_in_place(to_drop);
+}
+
+#[lang = "panic"]
+#[track_caller]
+#[no_mangle]
+pub fn panic(_msg: &str) -> ! {
+    unsafe {
+        libc::puts("Panicking\0" as *const str as *const u8);
+        intrinsics::abort();
+    }
+}
+
+#[lang = "panic_location"]
+struct PanicLocation {
+    file: &'static str,
+    line: u32,
+    column: u32,
+}
+
+#[lang = "panic_bounds_check"]
+#[track_caller]
+#[no_mangle]
+fn panic_bounds_check(index: usize, len: usize) -> ! {
+    unsafe {
+        libc::printf("index out of bounds: the len is %d but the index is %d\n\0" as *const str as *const i8, len, index);
+        intrinsics::abort();
+    }
+}
+
+mod intrinsics {
+    extern "rust-intrinsic" {
+        pub fn abort() -> !;
+    }
+}
+
+#[lang = "add"]
+trait Add<RHS = Self> {
+    type Output;
+
+    fn add(self, rhs: RHS) -> Self::Output;
+}
+
+impl Add for u8 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for i8 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for i32 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for usize {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for isize {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+#[lang = "sub"]
+pub trait Sub<RHS = Self> {
+    type Output;
+
+    fn sub(self, rhs: RHS) -> Self::Output;
+}
+
+impl Sub for usize {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for isize {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for u8 {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for i8 {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for i16 {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+
+/*
+ * Code
+ */
+
+fn i16_as_i8(a: i16) -> i8 {
+    a as i8
+}
+
+fn call_func(func: fn(i16) -> i8, param: i16) -> i8 {
+    func(param)
+}
+
+#[start]
+fn main(argc: isize, _argv: *const *const u8) -> isize {
+    unsafe {
+        let result = call_func(i16_as_i8, argc as i16) as isize;
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, result);
+    }
+    0
+}
diff --git a/compiler/rustc_codegen_gcc/tests/run/int_overflow.rs b/compiler/rustc_codegen_gcc/tests/run/int_overflow.rs
new file mode 100644
index 00000000000..7111703ca25
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/run/int_overflow.rs
@@ -0,0 +1,129 @@
+// Compiler:
+//
+// Run-time:
+//   stdout: Panicking
+//   status: signal
+
+#![allow(unused_attributes)]
+#![feature(auto_traits, lang_items, no_core, start, intrinsics)]
+
+#![no_std]
+#![no_core]
+
+/*
+ * Core
+ */
+
+// Because we don't have core yet.
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "copy"]
+trait Copy {
+}
+
+impl Copy for isize {}
+impl Copy for *mut i32 {}
+impl Copy for usize {}
+impl Copy for i32 {}
+impl Copy for u8 {}
+impl Copy for i8 {}
+
+#[lang = "receiver"]
+trait Receiver {
+}
+
+#[lang = "freeze"]
+pub(crate) unsafe auto trait Freeze {}
+
+#[lang = "panic_location"]
+struct PanicLocation {
+    file: &'static str,
+    line: u32,
+    column: u32,
+}
+
+mod libc {
+    #[link(name = "c")]
+    extern "C" {
+        pub fn puts(s: *const u8) -> i32;
+        pub fn fflush(stream: *mut i32) -> i32;
+
+        pub static STDOUT: *mut i32;
+    }
+}
+
+mod intrinsics {
+    extern "rust-intrinsic" {
+        pub fn abort() -> !;
+    }
+}
+
+#[lang = "panic"]
+#[track_caller]
+#[no_mangle]
+pub fn panic(_msg: &str) -> ! {
+    unsafe {
+        libc::puts("Panicking\0" as *const str as *const u8);
+        libc::fflush(libc::STDOUT);
+        intrinsics::abort();
+    }
+}
+
+#[lang = "add"]
+trait Add<RHS = Self> {
+    type Output;
+
+    fn add(self, rhs: RHS) -> Self::Output;
+}
+
+impl Add for u8 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for i8 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for i32 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for usize {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for isize {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+/*
+ * Code
+ */
+
+#[start]
+fn main(mut argc: isize, _argv: *const *const u8) -> isize {
+    let int = 9223372036854775807isize;
+    let int = int + argc;
+    int
+}
diff --git a/compiler/rustc_codegen_gcc/tests/run/mut_ref.rs b/compiler/rustc_codegen_gcc/tests/run/mut_ref.rs
new file mode 100644
index 00000000000..e8876009cc6
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/run/mut_ref.rs
@@ -0,0 +1,165 @@
+
+// Compiler:
+//
+// Run-time:
+//   stdout: 2
+//     7
+//     6
+//     11
+
+#![allow(unused_attributes)]
+#![feature(auto_traits, lang_items, no_core, start, intrinsics, track_caller)]
+
+#![no_std]
+#![no_core]
+
+/*
+ * Core
+ */
+
+// Because we don't have core yet.
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "copy"]
+trait Copy {
+}
+
+impl Copy for isize {}
+impl Copy for *mut i32 {}
+impl Copy for usize {}
+impl Copy for u8 {}
+impl Copy for i8 {}
+impl Copy for i32 {}
+
+#[lang = "receiver"]
+trait Receiver {
+}
+
+#[lang = "freeze"]
+pub(crate) unsafe auto trait Freeze {}
+
+#[lang = "panic_location"]
+struct PanicLocation {
+    file: &'static str,
+    line: u32,
+    column: u32,
+}
+
+mod libc {
+    #[link(name = "c")]
+    extern "C" {
+        pub fn puts(s: *const u8) -> i32;
+        pub fn fflush(stream: *mut i32) -> i32;
+        pub fn printf(format: *const i8, ...) -> i32;
+
+        pub static STDOUT: *mut i32;
+    }
+}
+
+mod intrinsics {
+    extern "rust-intrinsic" {
+        pub fn abort() -> !;
+    }
+}
+
+#[lang = "panic"]
+#[track_caller]
+#[no_mangle]
+pub fn panic(_msg: &str) -> ! {
+    unsafe {
+        libc::puts("Panicking\0" as *const str as *const u8);
+        libc::fflush(libc::STDOUT);
+        intrinsics::abort();
+    }
+}
+
+#[lang = "add"]
+trait Add<RHS = Self> {
+    type Output;
+
+    fn add(self, rhs: RHS) -> Self::Output;
+}
+
+impl Add for u8 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for i8 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for i32 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for usize {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for isize {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+/*
+ * Code
+ */
+
+struct Test {
+    field: isize,
+}
+
+fn test(num: isize) -> Test {
+    Test {
+        field: num + 1,
+    }
+}
+
+fn update_num(num: &mut isize) {
+    *num = *num + 5;
+}
+
+#[start]
+fn main(mut argc: isize, _argv: *const *const u8) -> isize {
+    let mut test = test(argc);
+    unsafe {
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, test.field);
+    }
+    update_num(&mut test.field);
+    unsafe {
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, test.field);
+    }
+
+    update_num(&mut argc);
+    unsafe {
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, argc);
+    }
+
+    let refe = &mut argc;
+    *refe = *refe + 5;
+    unsafe {
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, argc);
+    }
+
+    0
+}
diff --git a/compiler/rustc_codegen_gcc/tests/run/operations.rs b/compiler/rustc_codegen_gcc/tests/run/operations.rs
new file mode 100644
index 00000000000..4dc375309e4
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/run/operations.rs
@@ -0,0 +1,221 @@
+// Compiler:
+//
+// Run-time:
+//   stdout: 41
+//     39
+//     10
+
+#![allow(unused_attributes)]
+#![feature(auto_traits, lang_items, no_core, start, intrinsics, arbitrary_self_types)]
+
+#![no_std]
+#![no_core]
+
+/*
+ * Core
+ */
+
+// Because we don't have core yet.
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "copy"]
+trait Copy {
+}
+
+impl Copy for isize {}
+impl Copy for *mut i32 {}
+impl Copy for usize {}
+impl Copy for u8 {}
+impl Copy for i8 {}
+impl Copy for i16 {}
+impl Copy for i32 {}
+
+#[lang = "deref"]
+pub trait Deref {
+    type Target: ?Sized;
+
+    fn deref(&self) -> &Self::Target;
+}
+
+#[lang = "receiver"]
+trait Receiver {
+}
+
+#[lang = "freeze"]
+pub(crate) unsafe auto trait Freeze {}
+
+#[lang = "panic_location"]
+struct PanicLocation {
+    file: &'static str,
+    line: u32,
+    column: u32,
+}
+
+mod libc {
+    #[link(name = "c")]
+    extern "C" {
+        pub fn printf(format: *const i8, ...) -> i32;
+        pub fn puts(s: *const u8) -> i32;
+        pub fn fflush(stream: *mut i32) -> i32;
+
+        pub static STDOUT: *mut i32;
+    }
+}
+
+mod intrinsics {
+    extern "rust-intrinsic" {
+        pub fn abort() -> !;
+    }
+}
+
+#[lang = "panic"]
+#[track_caller]
+#[no_mangle]
+pub fn panic(_msg: &str) -> ! {
+    unsafe {
+        libc::puts("Panicking\0" as *const str as *const u8);
+        libc::fflush(libc::STDOUT);
+        intrinsics::abort();
+    }
+}
+
+#[lang = "add"]
+trait Add<RHS = Self> {
+    type Output;
+
+    fn add(self, rhs: RHS) -> Self::Output;
+}
+
+impl Add for u8 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for i8 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for i32 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for usize {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for isize {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+#[lang = "sub"]
+pub trait Sub<RHS = Self> {
+    type Output;
+
+    fn sub(self, rhs: RHS) -> Self::Output;
+}
+
+impl Sub for usize {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for isize {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for u8 {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for i8 {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for i16 {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+#[lang = "mul"]
+pub trait Mul<RHS = Self> {
+    type Output;
+
+    #[must_use]
+    fn mul(self, rhs: RHS) -> Self::Output;
+}
+
+impl Mul for u8 {
+    type Output = Self;
+
+    fn mul(self, rhs: Self) -> Self::Output {
+        self * rhs
+    }
+}
+
+impl Mul for usize {
+    type Output = Self;
+
+    fn mul(self, rhs: Self) -> Self::Output {
+        self * rhs
+    }
+}
+
+impl Mul for isize {
+    type Output = Self;
+
+    fn mul(self, rhs: Self) -> Self::Output {
+        self * rhs
+    }
+}
+
+/*
+ * Code
+ */
+
+#[start]
+fn main(mut argc: isize, _argv: *const *const u8) -> isize {
+    unsafe {
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, 40 + argc);
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, 40 - argc);
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, 10 * argc);
+    }
+    0
+}
diff --git a/compiler/rustc_codegen_gcc/tests/run/ptr_cast.rs b/compiler/rustc_codegen_gcc/tests/run/ptr_cast.rs
new file mode 100644
index 00000000000..6ac099ea145
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/run/ptr_cast.rs
@@ -0,0 +1,222 @@
+// Compiler:
+//
+// Run-time:
+//   status: 0
+//   stdout: 1
+
+#![feature(arbitrary_self_types, auto_traits, lang_items, no_core, start, intrinsics)]
+
+#![no_std]
+#![no_core]
+
+/*
+ * Core
+ */
+
+// Because we don't have core yet.
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "copy"]
+trait Copy {
+}
+
+impl Copy for isize {}
+impl Copy for usize {}
+impl Copy for i32 {}
+impl Copy for u8 {}
+impl Copy for i8 {}
+impl Copy for i16 {}
+
+#[lang = "receiver"]
+trait Receiver {
+}
+
+#[lang = "freeze"]
+pub(crate) unsafe auto trait Freeze {}
+
+mod libc {
+    #[link(name = "c")]
+    extern "C" {
+        pub fn printf(format: *const i8, ...) -> i32;
+        pub fn puts(s: *const u8) -> i32;
+    }
+}
+
+#[lang = "index"]
+pub trait Index<Idx: ?Sized> {
+    type Output: ?Sized;
+    fn index(&self, index: Idx) -> &Self::Output;
+}
+
+impl<T> Index<usize> for [T; 3] {
+    type Output = T;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        &self[index]
+    }
+}
+
+impl<T> Index<usize> for [T] {
+    type Output = T;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        &self[index]
+    }
+}
+
+#[lang = "drop_in_place"]
+#[allow(unconditional_recursion)]
+pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
+    // Code here does not matter - this is replaced by the
+    // real drop glue by the compiler.
+    drop_in_place(to_drop);
+}
+
+#[lang = "panic"]
+#[track_caller]
+#[no_mangle]
+pub fn panic(_msg: &str) -> ! {
+    unsafe {
+        libc::puts("Panicking\0" as *const str as *const u8);
+        intrinsics::abort();
+    }
+}
+
+#[lang = "panic_location"]
+struct PanicLocation {
+    file: &'static str,
+    line: u32,
+    column: u32,
+}
+
+#[lang = "panic_bounds_check"]
+#[track_caller]
+#[no_mangle]
+fn panic_bounds_check(index: usize, len: usize) -> ! {
+    unsafe {
+        libc::printf("index out of bounds: the len is %d but the index is %d\n\0" as *const str as *const i8, len, index);
+        intrinsics::abort();
+    }
+}
+
+mod intrinsics {
+    extern "rust-intrinsic" {
+        pub fn abort() -> !;
+    }
+}
+
+#[lang = "add"]
+trait Add<RHS = Self> {
+    type Output;
+
+    fn add(self, rhs: RHS) -> Self::Output;
+}
+
+impl Add for u8 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for i8 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for i32 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for usize {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl Add for isize {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+#[lang = "sub"]
+pub trait Sub<RHS = Self> {
+    type Output;
+
+    fn sub(self, rhs: RHS) -> Self::Output;
+}
+
+impl Sub for usize {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for isize {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for u8 {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for i8 {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+impl Sub for i16 {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+
+/*
+ * Code
+ */
+
+static mut ONE: usize = 1;
+
+fn make_array() -> [u8; 3] {
+    [42, 10, 5]
+}
+
+#[start]
+fn main(argc: isize, _argv: *const *const u8) -> isize {
+    unsafe {
+        let ptr = ONE as *mut usize;
+        let value = ptr as usize;
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, value);
+    }
+    0
+}
diff --git a/compiler/rustc_codegen_gcc/tests/run/return-tuple.rs b/compiler/rustc_codegen_gcc/tests/run/return-tuple.rs
new file mode 100644
index 00000000000..6fa10dca06f
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/run/return-tuple.rs
@@ -0,0 +1,72 @@
+// Compiler:
+//
+// Run-time:
+//   status: 0
+//   stdout: 10
+//     10
+//     42
+
+#![feature(auto_traits, lang_items, no_core, start, intrinsics)]
+
+#![no_std]
+#![no_core]
+
+#[lang = "copy"]
+pub unsafe trait Copy {}
+
+unsafe impl Copy for bool {}
+unsafe impl Copy for u8 {}
+unsafe impl Copy for u16 {}
+unsafe impl Copy for u32 {}
+unsafe impl Copy for u64 {}
+unsafe impl Copy for usize {}
+unsafe impl Copy for i8 {}
+unsafe impl Copy for i16 {}
+unsafe impl Copy for i32 {}
+unsafe impl Copy for isize {}
+unsafe impl Copy for f32 {}
+unsafe impl Copy for char {}
+
+mod libc {
+    #[link(name = "c")]
+    extern "C" {
+        pub fn printf(format: *const i8, ...) -> i32;
+    }
+}
+
+/*
+ * Core
+ */
+
+// Because we don't have core yet.
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "receiver"]
+trait Receiver {
+}
+
+#[lang = "freeze"]
+pub(crate) unsafe auto trait Freeze {}
+
+/*
+ * Code
+ */
+
+fn int_cast(a: u16, b: i16) -> (u8, u16, u32, usize, i8, i16, i32, isize, u8, u32) {
+    (
+        a as u8, a as u16, a as u32, a as usize, a as i8, a as i16, a as i32, a as isize, b as u8,
+        b as u32,
+    )
+}
+
+#[start]
+fn main(argc: isize, _argv: *const *const u8) -> isize {
+    let (a, b, c, d, e, f, g, h, i, j) = int_cast(10, 42);
+    unsafe {
+        libc::printf(b"%d\n\0" as *const u8 as *const i8, c);
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, d);
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, j);
+    }
+    0
+}
diff --git a/compiler/rustc_codegen_gcc/tests/run/slice.rs b/compiler/rustc_codegen_gcc/tests/run/slice.rs
new file mode 100644
index 00000000000..ad9258ed0bd
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/run/slice.rs
@@ -0,0 +1,128 @@
+// Compiler:
+//
+// Run-time:
+//   status: 0
+//   stdout: 5
+
+#![feature(arbitrary_self_types, auto_traits, lang_items, no_core, start, intrinsics)]
+
+#![no_std]
+#![no_core]
+
+/*
+ * Core
+ */
+
+// Because we don't have core yet.
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "copy"]
+trait Copy {
+}
+
+impl Copy for isize {}
+impl Copy for usize {}
+impl Copy for i32 {}
+impl Copy for u32 {}
+
+#[lang = "receiver"]
+trait Receiver {
+}
+
+#[lang = "freeze"]
+pub(crate) unsafe auto trait Freeze {}
+
+mod libc {
+    #[link(name = "c")]
+    extern "C" {
+        pub fn printf(format: *const i8, ...) -> i32;
+    }
+}
+
+#[lang = "index"]
+pub trait Index<Idx: ?Sized> {
+    type Output: ?Sized;
+    fn index(&self, index: Idx) -> &Self::Output;
+}
+
+impl<T> Index<usize> for [T; 3] {
+    type Output = T;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        &self[index]
+    }
+}
+
+impl<T> Index<usize> for [T] {
+    type Output = T;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        &self[index]
+    }
+}
+
+#[lang = "unsize"]
+pub trait Unsize<T: ?Sized> {}
+
+#[lang = "coerce_unsized"]
+pub trait CoerceUnsized<T> {}
+
+impl<'a, 'b: 'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<&'a U> for &'b T {}
+impl<'a, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<&'a mut U> for &'a mut T {}
+impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for *const T {}
+impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<*mut U> for *mut T {}
+
+#[lang = "drop_in_place"]
+#[allow(unconditional_recursion)]
+pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
+    // Code here does not matter - this is replaced by the
+    // real drop glue by the compiler.
+    drop_in_place(to_drop);
+}
+
+#[lang = "panic_location"]
+struct PanicLocation {
+    file: &'static str,
+    line: u32,
+    column: u32,
+}
+
+#[lang = "panic_bounds_check"]
+#[track_caller]
+#[no_mangle]
+fn panic_bounds_check(index: usize, len: usize) -> ! {
+    unsafe {
+        libc::printf("index out of bounds: the len is %d but the index is %d\n\0" as *const str as *const i8, len, index);
+        intrinsics::abort();
+    }
+}
+
+mod intrinsics {
+    use super::Sized;
+
+    extern "rust-intrinsic" {
+        pub fn abort() -> !;
+    }
+}
+
+/*
+ * Code
+ */
+
+static mut TWO: usize = 2;
+
+fn index_slice(s: &[u32]) -> u32 {
+    unsafe {
+        s[TWO]
+    }
+}
+
+#[start]
+fn main(mut argc: isize, _argv: *const *const u8) -> isize {
+    let array = [42, 7, 5];
+    unsafe {
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, index_slice(&array));
+    }
+    0
+}
diff --git a/compiler/rustc_codegen_gcc/tests/run/static.rs b/compiler/rustc_codegen_gcc/tests/run/static.rs
new file mode 100644
index 00000000000..ab89f6aff4b
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/run/static.rs
@@ -0,0 +1,106 @@
+// Compiler:
+//
+// Run-time:
+//   status: 0
+//   stdout: 10
+//      14
+//      1
+//      12
+//      12
+//      1
+
+#![feature(auto_traits, lang_items, no_core, start, intrinsics)]
+
+#![no_std]
+#![no_core]
+
+/*
+ * Core
+ */
+
+// Because we don't have core yet.
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "copy"]
+trait Copy {
+}
+
+impl Copy for isize {}
+
+#[lang = "receiver"]
+trait Receiver {
+}
+
+#[lang = "freeze"]
+pub(crate) unsafe auto trait Freeze {}
+
+mod intrinsics {
+    use super::Sized;
+
+    extern "rust-intrinsic" {
+        pub fn abort() -> !;
+    }
+}
+
+mod libc {
+    #[link(name = "c")]
+    extern "C" {
+        pub fn printf(format: *const i8, ...) -> i32;
+    }
+}
+
+#[lang = "structural_peq"]
+pub trait StructuralPartialEq {}
+
+#[lang = "structural_teq"]
+pub trait StructuralEq {}
+
+#[lang = "drop_in_place"]
+#[allow(unconditional_recursion)]
+pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
+    // Code here does not matter - this is replaced by the
+    // real drop glue by the compiler.
+    drop_in_place(to_drop);
+}
+
+/*
+ * Code
+ */
+
+struct Test {
+    field: isize,
+}
+
+struct WithRef {
+    refe: &'static Test,
+}
+
+static mut CONSTANT: isize = 10;
+
+static mut TEST: Test = Test {
+    field: 12,
+};
+
+static mut TEST2: Test = Test {
+    field: 14,
+};
+
+static mut WITH_REF: WithRef = WithRef {
+    refe: unsafe { &TEST },
+};
+
+#[start]
+fn main(mut argc: isize, _argv: *const *const u8) -> isize {
+    unsafe {
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, CONSTANT);
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, TEST2.field);
+        TEST2.field = argc;
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, TEST2.field);
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, WITH_REF.refe.field);
+        WITH_REF.refe = &TEST2;
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, TEST.field);
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, WITH_REF.refe.field);
+    }
+    0
+}
diff --git a/compiler/rustc_codegen_gcc/tests/run/structs.rs b/compiler/rustc_codegen_gcc/tests/run/structs.rs
new file mode 100644
index 00000000000..6c8884855ac
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/run/structs.rs
@@ -0,0 +1,70 @@
+// Compiler:
+//
+// Run-time:
+//   status: 0
+//   stdout: 1
+//     2
+
+#![feature(auto_traits, lang_items, no_core, start, intrinsics)]
+
+#![no_std]
+#![no_core]
+
+/*
+ * Core
+ */
+
+// Because we don't have core yet.
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "copy"]
+trait Copy {
+}
+
+impl Copy for isize {}
+
+#[lang = "receiver"]
+trait Receiver {
+}
+
+#[lang = "freeze"]
+pub(crate) unsafe auto trait Freeze {}
+
+mod libc {
+    #[link(name = "c")]
+    extern "C" {
+        pub fn printf(format: *const i8, ...) -> i32;
+    }
+}
+
+/*
+ * Code
+ */
+
+struct Test {
+    field: isize,
+}
+
+struct Two {
+    two: isize,
+}
+
+fn one() -> isize {
+    1
+}
+
+#[start]
+fn main(mut argc: isize, _argv: *const *const u8) -> isize {
+    let test = Test {
+        field: one(),
+    };
+    let two = Two {
+        two: 2,
+    };
+    unsafe {
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, test.field);
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, two.two);
+    }
+    0
+}
diff --git a/compiler/rustc_codegen_gcc/tests/run/tuple.rs b/compiler/rustc_codegen_gcc/tests/run/tuple.rs
new file mode 100644
index 00000000000..0b670bf2674
--- /dev/null
+++ b/compiler/rustc_codegen_gcc/tests/run/tuple.rs
@@ -0,0 +1,51 @@
+// Compiler:
+//
+// Run-time:
+//   status: 0
+//   stdout: 3
+
+#![feature(auto_traits, lang_items, no_core, start, intrinsics)]
+
+#![no_std]
+#![no_core]
+
+/*
+ * Core
+ */
+
+// Because we don't have core yet.
+#[lang = "sized"]
+pub trait Sized {}
+
+#[lang = "copy"]
+trait Copy {
+}
+
+impl Copy for isize {}
+
+#[lang = "receiver"]
+trait Receiver {
+}
+
+#[lang = "freeze"]
+pub(crate) unsafe auto trait Freeze {}
+
+mod libc {
+    #[link(name = "c")]
+    extern "C" {
+        pub fn printf(format: *const i8, ...) -> i32;
+    }
+}
+
+/*
+ * Code
+ */
+
+#[start]
+fn main(mut argc: isize, _argv: *const *const u8) -> isize {
+    let test: (isize, isize, isize) = (3, 1, 4);
+    unsafe {
+        libc::printf(b"%ld\n\0" as *const u8 as *const i8, test.0);
+    }
+    0
+}
diff --git a/compiler/rustc_codegen_llvm/src/back/write.rs b/compiler/rustc_codegen_llvm/src/back/write.rs
index 92199f611ba..9b0e7526894 100644
--- a/compiler/rustc_codegen_llvm/src/back/write.rs
+++ b/compiler/rustc_codegen_llvm/src/back/write.rs
@@ -129,7 +129,8 @@ fn to_pass_builder_opt_level(cfg: config::OptLevel) -> llvm::PassBuilderOptLevel
 fn to_llvm_relocation_model(relocation_model: RelocModel) -> llvm::RelocModel {
     match relocation_model {
         RelocModel::Static => llvm::RelocModel::Static,
-        RelocModel::Pic => llvm::RelocModel::PIC,
+        // LLVM doesn't have a PIE relocation model, it represents PIE as PIC with an extra attribute.
+        RelocModel::Pic | RelocModel::Pie => llvm::RelocModel::PIC,
         RelocModel::DynamicNoPic => llvm::RelocModel::DynamicNoPic,
         RelocModel::Ropi => llvm::RelocModel::ROPI,
         RelocModel::Rwpi => llvm::RelocModel::RWPI,
diff --git a/compiler/rustc_codegen_llvm/src/base.rs b/compiler/rustc_codegen_llvm/src/base.rs
index a6bdbd11899..3026c2fa030 100644
--- a/compiler/rustc_codegen_llvm/src/base.rs
+++ b/compiler/rustc_codegen_llvm/src/base.rs
@@ -25,9 +25,9 @@ use rustc_codegen_ssa::mono_item::MonoItemExt;
 use rustc_codegen_ssa::traits::*;
 use rustc_codegen_ssa::{ModuleCodegen, ModuleKind};
 use rustc_data_structures::small_c_str::SmallCStr;
+use rustc_metadata::EncodedMetadata;
 use rustc_middle::dep_graph;
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
-use rustc_middle::middle::cstore::EncodedMetadata;
 use rustc_middle::middle::exported_symbols;
 use rustc_middle::mir::mono::{Linkage, Visibility};
 use rustc_middle::ty::TyCtxt;
@@ -64,7 +64,7 @@ pub fn write_compressed_metadata<'tcx>(
 
     let (metadata_llcx, metadata_llmod) = (&*llvm_module.llcx, llvm_module.llmod());
     let mut compressed = rustc_metadata::METADATA_HEADER.to_vec();
-    FrameEncoder::new(&mut compressed).write_all(&metadata.raw_data).unwrap();
+    FrameEncoder::new(&mut compressed).write_all(metadata.raw_data()).unwrap();
 
     let llmeta = common::bytes_in_context(metadata_llcx, &compressed);
     let llconst = common::struct_in_context(metadata_llcx, &[llmeta], false);
diff --git a/compiler/rustc_codegen_llvm/src/context.rs b/compiler/rustc_codegen_llvm/src/context.rs
index 52a12b2fd81..7bdbec11d60 100644
--- a/compiler/rustc_codegen_llvm/src/context.rs
+++ b/compiler/rustc_codegen_llvm/src/context.rs
@@ -195,11 +195,14 @@ pub unsafe fn create_module(
     let llvm_target = SmallCStr::new(&sess.target.llvm_target);
     llvm::LLVMRustSetNormalizedTarget(llmod, llvm_target.as_ptr());
 
-    if sess.relocation_model() == RelocModel::Pic {
+    let reloc_model = sess.relocation_model();
+    if matches!(reloc_model, RelocModel::Pic | RelocModel::Pie) {
         llvm::LLVMRustSetModulePICLevel(llmod);
         // PIE is potentially more effective than PIC, but can only be used in executables.
         // If all our outputs are executables, then we can relax PIC to PIE.
-        if sess.crate_types().iter().all(|ty| *ty == CrateType::Executable) {
+        if reloc_model == RelocModel::Pie
+            || sess.crate_types().iter().all(|ty| *ty == CrateType::Executable)
+        {
             llvm::LLVMRustSetModulePIELevel(llmod);
         }
     }
diff --git a/compiler/rustc_codegen_llvm/src/lib.rs b/compiler/rustc_codegen_llvm/src/lib.rs
index 1da14344b1d..c44cc656056 100644
--- a/compiler/rustc_codegen_llvm/src/lib.rs
+++ b/compiler/rustc_codegen_llvm/src/lib.rs
@@ -27,8 +27,8 @@ use rustc_codegen_ssa::ModuleCodegen;
 use rustc_codegen_ssa::{CodegenResults, CompiledModule};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::{ErrorReported, FatalError, Handler};
+use rustc_metadata::EncodedMetadata;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
-use rustc_middle::middle::cstore::EncodedMetadata;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::config::{OptLevel, OutputFilenames, PrintRequest};
 use rustc_session::Session;
@@ -211,9 +211,16 @@ impl CodegenBackend for LlvmCodegenBackend {
         match req {
             PrintRequest::RelocationModels => {
                 println!("Available relocation models:");
-                for name in
-                    &["static", "pic", "dynamic-no-pic", "ropi", "rwpi", "ropi-rwpi", "default"]
-                {
+                for name in &[
+                    "static",
+                    "pic",
+                    "pie",
+                    "dynamic-no-pic",
+                    "ropi",
+                    "rwpi",
+                    "ropi-rwpi",
+                    "default",
+                ] {
                     println!("    {}", name);
                 }
                 println!();
diff --git a/compiler/rustc_codegen_llvm/src/mono_item.rs b/compiler/rustc_codegen_llvm/src/mono_item.rs
index 34982f769d0..b9022a391e6 100644
--- a/compiler/rustc_codegen_llvm/src/mono_item.rs
+++ b/compiler/rustc_codegen_llvm/src/mono_item.rs
@@ -143,6 +143,12 @@ impl CodegenCx<'ll, 'tcx> {
             return true;
         }
 
+        // With pie relocation model calls of functions defined in the translation
+        // unit can use copy relocations.
+        if self.tcx.sess.relocation_model() == RelocModel::Pie && !is_declaration {
+            return true;
+        }
+
         return false;
     }
 }
diff --git a/compiler/rustc_codegen_ssa/Cargo.toml b/compiler/rustc_codegen_ssa/Cargo.toml
index 0713e167c53..54641df6179 100644
--- a/compiler/rustc_codegen_ssa/Cargo.toml
+++ b/compiler/rustc_codegen_ssa/Cargo.toml
@@ -32,6 +32,7 @@ rustc_hir = { path = "../rustc_hir" }
 rustc_incremental = { path = "../rustc_incremental" }
 rustc_index = { path = "../rustc_index" }
 rustc_macros = { path = "../rustc_macros" }
+rustc_metadata = { path = "../rustc_metadata" }
 rustc_target = { path = "../rustc_target" }
 rustc_session = { path = "../rustc_session" }
 
diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index 826c09cd948..43affdebbaf 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -327,7 +327,7 @@ fn link_rlib<'a, B: ArchiveBuilder<'a>>(
             // metadata in rlib files is wrapped in a "dummy" object file for
             // the target platform so the rlib can be processed entirely by
             // normal linkers for the platform.
-            let metadata = create_metadata_file(sess, &codegen_results.metadata.raw_data);
+            let metadata = create_metadata_file(sess, codegen_results.metadata.raw_data());
             ab.add_file(&emit_metadata(sess, &metadata, tmpdir));
 
             // After adding all files to the archive, we need to update the
@@ -1490,9 +1490,13 @@ fn exec_linker(
 fn link_output_kind(sess: &Session, crate_type: CrateType) -> LinkOutputKind {
     let kind = match (crate_type, sess.crt_static(Some(crate_type)), sess.relocation_model()) {
         (CrateType::Executable, _, _) if sess.is_wasi_reactor() => LinkOutputKind::WasiReactorExe,
-        (CrateType::Executable, false, RelocModel::Pic) => LinkOutputKind::DynamicPicExe,
+        (CrateType::Executable, false, RelocModel::Pic | RelocModel::Pie) => {
+            LinkOutputKind::DynamicPicExe
+        }
         (CrateType::Executable, false, _) => LinkOutputKind::DynamicNoPicExe,
-        (CrateType::Executable, true, RelocModel::Pic) => LinkOutputKind::StaticPicExe,
+        (CrateType::Executable, true, RelocModel::Pic | RelocModel::Pie) => {
+            LinkOutputKind::StaticPicExe
+        }
         (CrateType::Executable, true, _) => LinkOutputKind::StaticNoPicExe,
         (_, true, _) => LinkOutputKind::StaticDylib,
         (_, false, _) => LinkOutputKind::DynamicDylib,
diff --git a/compiler/rustc_codegen_ssa/src/back/write.rs b/compiler/rustc_codegen_ssa/src/back/write.rs
index 41823f7d80d..31722d07414 100644
--- a/compiler/rustc_codegen_ssa/src/back/write.rs
+++ b/compiler/rustc_codegen_ssa/src/back/write.rs
@@ -21,8 +21,8 @@ use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
 use rustc_incremental::{
     copy_cgu_workproduct_to_incr_comp_cache_dir, in_incr_comp_dir, in_incr_comp_dir_sess,
 };
+use rustc_metadata::EncodedMetadata;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
-use rustc_middle::middle::cstore::EncodedMetadata;
 use rustc_middle::middle::exported_symbols::SymbolExportLevel;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::cgu_reuse_tracker::CguReuseTracker;
diff --git a/compiler/rustc_codegen_ssa/src/base.rs b/compiler/rustc_codegen_ssa/src/base.rs
index a6bf1d8d1e5..9bb4982754c 100644
--- a/compiler/rustc_codegen_ssa/src/base.rs
+++ b/compiler/rustc_codegen_ssa/src/base.rs
@@ -18,8 +18,8 @@ use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
 use rustc_hir::lang_items::LangItem;
 use rustc_index::vec::Idx;
+use rustc_metadata::EncodedMetadata;
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
-use rustc_middle::middle::cstore::EncodedMetadata;
 use rustc_middle::middle::lang_items;
 use rustc_middle::mir::mono::{CodegenUnit, CodegenUnitNameBuilder, MonoItem};
 use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf, TyAndLayout};
diff --git a/compiler/rustc_codegen_ssa/src/lib.rs b/compiler/rustc_codegen_ssa/src/lib.rs
index 634286770d1..70b351f6433 100644
--- a/compiler/rustc_codegen_ssa/src/lib.rs
+++ b/compiler/rustc_codegen_ssa/src/lib.rs
@@ -158,7 +158,7 @@ pub struct CodegenResults {
     pub modules: Vec<CompiledModule>,
     pub allocator_module: Option<CompiledModule>,
     pub metadata_module: Option<CompiledModule>,
-    pub metadata: rustc_middle::middle::cstore::EncodedMetadata,
+    pub metadata: rustc_metadata::EncodedMetadata,
     pub crate_info: CrateInfo,
 }
 
diff --git a/compiler/rustc_codegen_ssa/src/traits/backend.rs b/compiler/rustc_codegen_ssa/src/traits/backend.rs
index 82b79fd0b2a..50a46877c5a 100644
--- a/compiler/rustc_codegen_ssa/src/traits/backend.rs
+++ b/compiler/rustc_codegen_ssa/src/traits/backend.rs
@@ -6,8 +6,9 @@ use crate::{CodegenResults, ModuleCodegen};
 use rustc_ast::expand::allocator::AllocatorKind;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::ErrorReported;
+use rustc_metadata::EncodedMetadata;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
-use rustc_middle::middle::cstore::{EncodedMetadata, MetadataLoaderDyn};
+use rustc_middle::middle::cstore::MetadataLoaderDyn;
 use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, LayoutOf, TyAndLayout};
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::{Ty, TyCtxt};
diff --git a/compiler/rustc_const_eval/src/interpret/step.rs b/compiler/rustc_const_eval/src/interpret/step.rs
index bcce19b28db..e6037d561de 100644
--- a/compiler/rustc_const_eval/src/interpret/step.rs
+++ b/compiler/rustc_const_eval/src/interpret/step.rs
@@ -197,12 +197,17 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             }
 
             Aggregate(ref kind, ref operands) => {
+                // active_field_index is for union initialization.
                 let (dest, active_field_index) = match **kind {
                     mir::AggregateKind::Adt(adt_def, variant_index, _, _, active_field_index) => {
                         self.write_discriminant(variant_index, &dest)?;
                         if adt_def.is_enum() {
-                            (self.place_downcast(&dest, variant_index)?, active_field_index)
+                            assert!(active_field_index.is_none());
+                            (self.place_downcast(&dest, variant_index)?, None)
                         } else {
+                            if active_field_index.is_some() {
+                                assert_eq!(operands.len(), 1);
+                            }
                             (dest, active_field_index)
                         }
                     }
@@ -211,12 +216,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
 
                 for (i, operand) in operands.iter().enumerate() {
                     let op = self.eval_operand(operand, None)?;
-                    // Ignore zero-sized fields.
-                    if !op.layout.is_zst() {
-                        let field_index = active_field_index.unwrap_or(i);
-                        let field_dest = self.place_field(&dest, field_index)?;
-                        self.copy_op(&op, &field_dest)?;
-                    }
+                    let field_index = active_field_index.unwrap_or(i);
+                    let field_dest = self.place_field(&dest, field_index)?;
+                    self.copy_op(&op, &field_dest)?;
                 }
             }
 
@@ -253,7 +255,6 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             }
 
             Len(place) => {
-                // FIXME(CTFE): don't allow computing the length of arrays in const eval
                 let src = self.eval_place(place)?;
                 let mplace = self.force_allocation(&src)?;
                 let len = mplace.len(self)?;
diff --git a/compiler/rustc_data_structures/src/graph/scc/mod.rs b/compiler/rustc_data_structures/src/graph/scc/mod.rs
index d8ac815a158..b84f28b6a9e 100644
--- a/compiler/rustc_data_structures/src/graph/scc/mod.rs
+++ b/compiler/rustc_data_structures/src/graph/scc/mod.rs
@@ -405,6 +405,7 @@ where
     /// Call this method when `inspect_node` has returned `None`. Having the
     /// caller decide avoids mutual recursion between the two methods and allows
     /// us to maintain an allocated stack for nodes on the path between calls.
+    #[instrument(skip(self, initial), level = "debug")]
     fn walk_unvisited_node(&mut self, initial: G::Node) -> WalkReturn<S> {
         struct VisitingNodeFrame<G: DirectedGraph, Successors> {
             node: G::Node,
@@ -451,7 +452,7 @@ where
                 Some(iter) => iter,
                 None => {
                     // This None marks that we still have the initialize this node's frame.
-                    debug!("walk_unvisited_node(depth = {:?}, node = {:?})", depth, node);
+                    debug!(?depth, ?node);
 
                     debug_assert!(matches!(self.node_states[node], NodeState::NotVisited));
 
@@ -478,10 +479,7 @@ where
                 return_value.take().into_iter().map(|walk| (*successor_node, Some(walk)));
 
             let successor_walk = successors.by_ref().map(|successor_node| {
-                debug!(
-                    "walk_unvisited_node: node = {:?} successor_ode = {:?}",
-                    node, successor_node
-                );
+                debug!(?node, ?successor_node);
                 (successor_node, self.inspect_node(successor_node))
             });
 
@@ -491,10 +489,7 @@ where
                         // Track the minimum depth we can reach.
                         assert!(successor_min_depth <= depth);
                         if successor_min_depth < *min_depth {
-                            debug!(
-                                "walk_unvisited_node: node = {:?} successor_min_depth = {:?}",
-                                node, successor_min_depth
-                            );
+                            debug!(?node, ?successor_min_depth);
                             *min_depth = successor_min_depth;
                             *min_cycle_root = successor_node;
                         }
@@ -503,16 +498,13 @@ where
                     Some(WalkReturn::Complete { scc_index: successor_scc_index }) => {
                         // Push the completed SCC indices onto
                         // the `successors_stack` for later.
-                        debug!(
-                            "walk_unvisited_node: node = {:?} successor_scc_index = {:?}",
-                            node, successor_scc_index
-                        );
+                        debug!(?node, ?successor_scc_index);
                         successors_stack.push(successor_scc_index);
                     }
 
                     None => {
                         let depth = depth + 1;
-                        debug!("walk_node(depth = {:?}, node = {:?})", depth, successor_node);
+                        debug!(?depth, ?successor_node);
                         // Remember which node the return value will come from.
                         frame.successor_node = successor_node;
                         // Start a new stack frame the step into it.
diff --git a/compiler/rustc_expand/src/expand.rs b/compiler/rustc_expand/src/expand.rs
index d32593f34ad..1d6703077ac 100644
--- a/compiler/rustc_expand/src/expand.rs
+++ b/compiler/rustc_expand/src/expand.rs
@@ -633,14 +633,18 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
 
     fn error_recursion_limit_reached(&mut self) {
         let expn_data = self.cx.current_expansion.id.expn_data();
-        let suggested_limit = self.cx.ecfg.recursion_limit * 2;
+        let suggested_limit = match self.cx.ecfg.recursion_limit {
+            Limit(0) => Limit(2),
+            limit => limit * 2,
+        };
         self.cx
             .struct_span_err(
                 expn_data.call_site,
                 &format!("recursion limit reached while expanding `{}`", expn_data.kind.descr()),
             )
             .help(&format!(
-                "consider adding a `#![recursion_limit=\"{}\"]` attribute to your crate (`{}`)",
+                "consider increasing the recursion limit by adding a \
+                 `#![recursion_limit = \"{}\"]` attribute to your crate (`{}`)",
                 suggested_limit, self.cx.ecfg.crate_name,
             ))
             .emit();
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index 05b652fd5af..9c275b316c5 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -384,6 +384,16 @@ impl GenericArgs<'_> {
         self.args.iter().any(|arg| matches!(arg, GenericArg::Type(_)))
     }
 
+    pub fn has_err(&self) -> bool {
+        self.args.iter().any(|arg| match arg {
+            GenericArg::Type(ty) => matches!(ty.kind, TyKind::Err),
+            _ => false,
+        }) || self.bindings.iter().any(|arg| match arg.kind {
+            TypeBindingKind::Equality { ty } => matches!(ty.kind, TyKind::Err),
+            _ => false,
+        })
+    }
+
     #[inline]
     pub fn num_type_params(&self) -> usize {
         self.args.iter().filter(|arg| matches!(arg, GenericArg::Type(_))).count()
diff --git a/compiler/rustc_hir/src/lang_items.rs b/compiler/rustc_hir/src/lang_items.rs
index d69a2470540..814054c5518 100644
--- a/compiler/rustc_hir/src/lang_items.rs
+++ b/compiler/rustc_hir/src/lang_items.rs
@@ -300,7 +300,7 @@ language_item_table! {
     Oom,                     sym::oom,                 oom,                        Target::Fn,             GenericRequirement::None;
     AllocLayout,             sym::alloc_layout,        alloc_layout,               Target::Struct,         GenericRequirement::None;
 
-    Start,                   sym::start,               start_fn,                   Target::Fn,             GenericRequirement::None;
+    Start,                   sym::start,               start_fn,                   Target::Fn,             GenericRequirement::Exact(1);
 
     EhPersonality,           sym::eh_personality,      eh_personality,             Target::Fn,             GenericRequirement::None;
     EhCatchTypeinfo,         sym::eh_catch_typeinfo,   eh_catch_typeinfo,          Target::Static,         GenericRequirement::None;
diff --git a/compiler/rustc_infer/src/infer/at.rs b/compiler/rustc_infer/src/infer/at.rs
index 11ee8fb17ad..cff848eeb6a 100644
--- a/compiler/rustc_infer/src/infer/at.rs
+++ b/compiler/rustc_infer/src/infer/at.rs
@@ -187,11 +187,11 @@ impl<'a, 'tcx> At<'a, 'tcx> {
 impl<'a, 'tcx> Trace<'a, 'tcx> {
     /// Makes `a <: b` where `a` may or may not be expected (if
     /// `a_is_expected` is true, then `a` is expected).
+    #[instrument(skip(self), level = "debug")]
     pub fn sub<T>(self, a: T, b: T) -> InferResult<'tcx, ()>
     where
         T: Relate<'tcx>,
     {
-        debug!("sub({:?} <: {:?})", a, b);
         let Trace { at, trace, a_is_expected } = self;
         at.infcx.commit_if_ok(|_| {
             let mut fields = at.infcx.combine_fields(trace, at.param_env);
@@ -204,11 +204,11 @@ impl<'a, 'tcx> Trace<'a, 'tcx> {
 
     /// Makes `a == b`; the expectation is set by the call to
     /// `trace()`.
+    #[instrument(skip(self), level = "debug")]
     pub fn eq<T>(self, a: T, b: T) -> InferResult<'tcx, ()>
     where
         T: Relate<'tcx>,
     {
-        debug!("eq({:?} == {:?})", a, b);
         let Trace { at, trace, a_is_expected } = self;
         at.infcx.commit_if_ok(|_| {
             let mut fields = at.infcx.combine_fields(trace, at.param_env);
@@ -219,11 +219,11 @@ impl<'a, 'tcx> Trace<'a, 'tcx> {
         })
     }
 
+    #[instrument(skip(self), level = "debug")]
     pub fn lub<T>(self, a: T, b: T) -> InferResult<'tcx, T>
     where
         T: Relate<'tcx>,
     {
-        debug!("lub({:?} \\/ {:?})", a, b);
         let Trace { at, trace, a_is_expected } = self;
         at.infcx.commit_if_ok(|_| {
             let mut fields = at.infcx.combine_fields(trace, at.param_env);
@@ -234,11 +234,11 @@ impl<'a, 'tcx> Trace<'a, 'tcx> {
         })
     }
 
+    #[instrument(skip(self), level = "debug")]
     pub fn glb<T>(self, a: T, b: T) -> InferResult<'tcx, T>
     where
         T: Relate<'tcx>,
     {
-        debug!("glb({:?} /\\ {:?})", a, b);
         let Trace { at, trace, a_is_expected } = self;
         at.infcx.commit_if_ok(|_| {
             let mut fields = at.infcx.combine_fields(trace, at.param_env);
diff --git a/compiler/rustc_infer/src/infer/canonical/query_response.rs b/compiler/rustc_infer/src/infer/canonical/query_response.rs
index b5c03072557..2296cc6129a 100644
--- a/compiler/rustc_infer/src/infer/canonical/query_response.rs
+++ b/compiler/rustc_infer/src/infer/canonical/query_response.rs
@@ -49,6 +49,7 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
     ///   the same thing happens, but the resulting query is marked as ambiguous.
     /// - Finally, if any of the obligations result in a hard error,
     ///   then `Err(NoSolution)` is returned.
+    #[instrument(skip(self, inference_vars, answer, fulfill_cx), level = "trace")]
     pub fn make_canonicalized_query_response<T>(
         &self,
         inference_vars: CanonicalVarValues<'tcx>,
@@ -62,7 +63,7 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
         let query_response = self.make_query_response(inference_vars, answer, fulfill_cx)?;
         let canonical_result = self.canonicalize_response(query_response);
 
-        debug!("make_canonicalized_query_response: canonical_result = {:#?}", canonical_result);
+        debug!("canonical_result = {:#?}", canonical_result);
 
         Ok(self.tcx.arena.alloc(canonical_result))
     }
@@ -94,6 +95,7 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
 
     /// Helper for `make_canonicalized_query_response` that does
     /// everything up until the final canonicalization.
+    #[instrument(skip(self, fulfill_cx), level = "debug")]
     fn make_query_response<T>(
         &self,
         inference_vars: CanonicalVarValues<'tcx>,
@@ -105,13 +107,6 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
     {
         let tcx = self.tcx;
 
-        debug!(
-            "make_query_response(\
-             inference_vars={:?}, \
-             answer={:?})",
-            inference_vars, answer,
-        );
-
         // Select everything, returning errors.
         let true_errors = fulfill_cx.select_where_possible(self).err().unwrap_or_else(Vec::new);
         debug!("true_errors = {:#?}", true_errors);
diff --git a/compiler/rustc_infer/src/infer/fudge.rs b/compiler/rustc_infer/src/infer/fudge.rs
index 35ebe92c592..773753a0363 100644
--- a/compiler/rustc_infer/src/infer/fudge.rs
+++ b/compiler/rustc_infer/src/infer/fudge.rs
@@ -94,13 +94,12 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
     /// the actual types (`?T`, `Option<?T>`) -- and remember that
     /// after the snapshot is popped, the variable `?T` is no longer
     /// unified.
+    #[instrument(skip(self, f), level = "debug")]
     pub fn fudge_inference_if_ok<T, E, F>(&self, f: F) -> Result<T, E>
     where
         F: FnOnce() -> Result<T, E>,
         T: TypeFoldable<'tcx>,
     {
-        debug!("fudge_inference_if_ok()");
-
         let variable_lengths = self.variable_lengths();
         let (mut fudger, value) = self.probe(|_| {
             match f() {
diff --git a/compiler/rustc_infer/src/infer/higher_ranked/mod.rs b/compiler/rustc_infer/src/infer/higher_ranked/mod.rs
index d460222df8a..ae85e55da6a 100644
--- a/compiler/rustc_infer/src/infer/higher_ranked/mod.rs
+++ b/compiler/rustc_infer/src/infer/higher_ranked/mod.rs
@@ -9,6 +9,7 @@ use rustc_middle::ty::relate::{Relate, RelateResult, TypeRelation};
 use rustc_middle::ty::{self, Binder, TypeFoldable};
 
 impl<'a, 'tcx> CombineFields<'a, 'tcx> {
+    #[instrument(skip(self), level = "debug")]
     pub fn higher_ranked_sub<T>(
         &mut self,
         a: Binder<'tcx, T>,
@@ -18,8 +19,6 @@ impl<'a, 'tcx> CombineFields<'a, 'tcx> {
     where
         T: Relate<'tcx>,
     {
-        debug!("higher_ranked_sub(a={:?}, b={:?})", a, b);
-
         // Rather than checking the subtype relationship between `a` and `b`
         // as-is, we need to do some extra work here in order to make sure
         // that function subtyping works correctly with respect to regions
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index 632e792bbd1..18836d5a68e 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -807,8 +807,8 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         }
     }
 
+    #[instrument(skip(self, snapshot), level = "debug")]
     fn rollback_to(&self, cause: &str, snapshot: CombinedSnapshot<'a, 'tcx>) {
-        debug!("rollback_to(cause={})", cause);
         let CombinedSnapshot {
             undo_snapshot,
             region_constraints_snapshot,
@@ -825,8 +825,8 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         inner.unwrap_region_constraints().rollback_to(region_constraints_snapshot);
     }
 
+    #[instrument(skip(self, snapshot), level = "debug")]
     fn commit_from(&self, snapshot: CombinedSnapshot<'a, 'tcx>) {
-        debug!("commit_from()");
         let CombinedSnapshot {
             undo_snapshot,
             region_constraints_snapshot: _,
@@ -841,11 +841,11 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
     }
 
     /// Executes `f` and commit the bindings.
+    #[instrument(skip(self, f), level = "debug")]
     pub fn commit_unconditionally<R, F>(&self, f: F) -> R
     where
         F: FnOnce(&CombinedSnapshot<'a, 'tcx>) -> R,
     {
-        debug!("commit_unconditionally()");
         let snapshot = self.start_snapshot();
         let r = f(&snapshot);
         self.commit_from(snapshot);
@@ -853,11 +853,11 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
     }
 
     /// Execute `f` and commit the bindings if closure `f` returns `Ok(_)`.
+    #[instrument(skip(self, f), level = "debug")]
     pub fn commit_if_ok<T, E, F>(&self, f: F) -> Result<T, E>
     where
         F: FnOnce(&CombinedSnapshot<'a, 'tcx>) -> Result<T, E>,
     {
-        debug!("commit_if_ok()");
         let snapshot = self.start_snapshot();
         let r = f(&snapshot);
         debug!("commit_if_ok() -- r.is_ok() = {}", r.is_ok());
@@ -873,11 +873,11 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
     }
 
     /// Execute `f` then unroll any bindings it creates.
+    #[instrument(skip(self, f), level = "debug")]
     pub fn probe<R, F>(&self, f: F) -> R
     where
         F: FnOnce(&CombinedSnapshot<'a, 'tcx>) -> R,
     {
-        debug!("probe()");
         let snapshot = self.start_snapshot();
         let r = f(&snapshot);
         self.rollback_to("probe", snapshot);
@@ -885,11 +885,11 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
     }
 
     /// If `should_skip` is true, then execute `f` then unroll any bindings it creates.
+    #[instrument(skip(self, f), level = "debug")]
     pub fn probe_maybe_skip_leak_check<R, F>(&self, should_skip: bool, f: F) -> R
     where
         F: FnOnce(&CombinedSnapshot<'a, 'tcx>) -> R,
     {
-        debug!("probe()");
         let snapshot = self.start_snapshot();
         let was_skip_leak_check = self.skip_leak_check.get();
         if should_skip {
@@ -946,18 +946,19 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         })
     }
 
+    #[instrument(skip(self), level = "debug")]
     pub fn sub_regions(
         &self,
         origin: SubregionOrigin<'tcx>,
         a: ty::Region<'tcx>,
         b: ty::Region<'tcx>,
     ) {
-        debug!("sub_regions({:?} <: {:?})", a, b);
         self.inner.borrow_mut().unwrap_region_constraints().make_subregion(origin, a, b);
     }
 
     /// Require that the region `r` be equal to one of the regions in
     /// the set `regions`.
+    #[instrument(skip(self), level = "debug")]
     pub fn member_constraint(
         &self,
         opaque_type_def_id: DefId,
@@ -966,7 +967,6 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         region: ty::Region<'tcx>,
         in_regions: &Lrc<Vec<ty::Region<'tcx>>>,
     ) {
-        debug!("member_constraint({:?} <: {:?})", region, in_regions);
         self.inner.borrow_mut().unwrap_region_constraints().member_constraint(
             opaque_type_def_id,
             definition_span,
diff --git a/compiler/rustc_infer/src/infer/nll_relate/mod.rs b/compiler/rustc_infer/src/infer/nll_relate/mod.rs
index 73d74584a5e..29a9cbc7a99 100644
--- a/compiler/rustc_infer/src/infer/nll_relate/mod.rs
+++ b/compiler/rustc_infer/src/infer/nll_relate/mod.rs
@@ -507,6 +507,7 @@ where
         true
     }
 
+    #[instrument(skip(self, info), level = "trace")]
     fn relate_with_variance<T: Relate<'tcx>>(
         &mut self,
         variance: ty::Variance,
@@ -514,23 +515,22 @@ where
         a: T,
         b: T,
     ) -> RelateResult<'tcx, T> {
-        debug!("relate_with_variance(variance={:?}, a={:?}, b={:?})", variance, a, b);
-
         let old_ambient_variance = self.ambient_variance;
         self.ambient_variance = self.ambient_variance.xform(variance);
         self.ambient_variance_info = self.ambient_variance_info.xform(info);
 
-        debug!("relate_with_variance: ambient_variance = {:?}", self.ambient_variance);
+        debug!(?self.ambient_variance);
 
         let r = self.relate(a, b)?;
 
         self.ambient_variance = old_ambient_variance;
 
-        debug!("relate_with_variance: r={:?}", r);
+        debug!(?r);
 
         Ok(r)
     }
 
+    #[instrument(skip(self), level = "debug")]
     fn tys(&mut self, a: Ty<'tcx>, mut b: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> {
         let a = self.infcx.shallow_resolve(a);
 
@@ -573,7 +573,7 @@ where
             }
 
             _ => {
-                debug!("tys(a={:?}, b={:?}, variance={:?})", a, b, self.ambient_variance);
+                debug!(?a, ?b, ?self.ambient_variance);
 
                 // Will also handle unification of `IntVar` and `FloatVar`.
                 self.infcx.super_combine_tys(self, a, b)
@@ -581,18 +581,19 @@ where
         }
     }
 
+    #[instrument(skip(self), level = "trace")]
     fn regions(
         &mut self,
         a: ty::Region<'tcx>,
         b: ty::Region<'tcx>,
     ) -> RelateResult<'tcx, ty::Region<'tcx>> {
-        debug!("regions(a={:?}, b={:?}, variance={:?})", a, b, self.ambient_variance);
+        debug!(?self.ambient_variance);
 
         let v_a = self.replace_bound_region(a, ty::INNERMOST, &self.a_scopes);
         let v_b = self.replace_bound_region(b, ty::INNERMOST, &self.b_scopes);
 
-        debug!("regions: v_a = {:?}", v_a);
-        debug!("regions: v_b = {:?}", v_b);
+        debug!(?v_a);
+        debug!(?v_b);
 
         if self.ambient_covariance() {
             // Covariance: a <= b. Hence, `b: a`.
@@ -628,6 +629,7 @@ where
         }
     }
 
+    #[instrument(skip(self), level = "trace")]
     fn binders<T>(
         &mut self,
         a: ty::Binder<'tcx, T>,
@@ -655,7 +657,7 @@ where
         // - Instantiate binders on `b` universally, yielding a universe U1.
         // - Instantiate binders on `a` existentially in U1.
 
-        debug!("binders({:?}: {:?}, ambient_variance={:?})", a, b, self.ambient_variance);
+        debug!(?self.ambient_variance);
 
         if let (Some(a), Some(b)) = (a.no_bound_vars(), b.no_bound_vars()) {
             // Fast path for the common case.
@@ -673,8 +675,8 @@ where
             let b_scope = self.create_scope(b, UniversallyQuantified(true));
             let a_scope = self.create_scope(a, UniversallyQuantified(false));
 
-            debug!("binders: a_scope = {:?} (existential)", a_scope);
-            debug!("binders: b_scope = {:?} (universal)", b_scope);
+            debug!(?a_scope, "(existential)");
+            debug!(?b_scope, "(universal)");
 
             self.b_scopes.push(b_scope);
             self.a_scopes.push(a_scope);
@@ -717,8 +719,8 @@ where
             let a_scope = self.create_scope(a, UniversallyQuantified(true));
             let b_scope = self.create_scope(b, UniversallyQuantified(false));
 
-            debug!("binders: a_scope = {:?} (universal)", a_scope);
-            debug!("binders: b_scope = {:?} (existential)", b_scope);
+            debug!(?a_scope, "(universal)");
+            debug!(?b_scope, "(existential)");
 
             self.a_scopes.push(a_scope);
             self.b_scopes.push(b_scope);
diff --git a/compiler/rustc_infer/src/infer/region_constraints/mod.rs b/compiler/rustc_infer/src/infer/region_constraints/mod.rs
index af31ab0923d..df4fdb3a982 100644
--- a/compiler/rustc_infer/src/infer/region_constraints/mod.rs
+++ b/compiler/rustc_infer/src/infer/region_constraints/mod.rs
@@ -540,6 +540,7 @@ impl<'tcx> RegionConstraintCollector<'_, 'tcx> {
         });
     }
 
+    #[instrument(skip(self, origin), level = "debug")]
     pub fn make_subregion(
         &mut self,
         origin: SubregionOrigin<'tcx>,
@@ -547,10 +548,7 @@ impl<'tcx> RegionConstraintCollector<'_, 'tcx> {
         sup: Region<'tcx>,
     ) {
         // cannot add constraints once regions are resolved
-        debug!(
-            "RegionConstraintCollector: make_subregion({:?}, {:?}) due to {:?}",
-            sub, sup, origin
-        );
+        debug!("origin = {:#?}", origin);
 
         match (sub, sup) {
             (&ReLateBound(..), _) | (_, &ReLateBound(..)) => {
diff --git a/compiler/rustc_interface/src/passes.rs b/compiler/rustc_interface/src/passes.rs
index 45ad2df8245..55a3fcd0266 100644
--- a/compiler/rustc_interface/src/passes.rs
+++ b/compiler/rustc_interface/src/passes.rs
@@ -16,9 +16,9 @@ use rustc_hir::def_id::{StableCrateId, LOCAL_CRATE};
 use rustc_hir::Crate;
 use rustc_lint::LintStore;
 use rustc_metadata::creader::CStore;
+use rustc_metadata::{encode_metadata, EncodedMetadata};
 use rustc_middle::arena::Arena;
 use rustc_middle::dep_graph::DepGraph;
-use rustc_middle::middle;
 use rustc_middle::middle::cstore::{MetadataLoader, MetadataLoaderDyn};
 use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::{self, GlobalCtxt, ResolverOutputs, TyCtxt};
@@ -179,7 +179,7 @@ pub fn register_plugins<'a>(
     register_lints: impl Fn(&Session, &mut LintStore),
     mut krate: ast::Crate,
     crate_name: &str,
-) -> Result<(ast::Crate, Lrc<LintStore>)> {
+) -> Result<(ast::Crate, LintStore)> {
     krate = sess.time("attributes_injection", || {
         rustc_builtin_macros::cmdline_attrs::inject(
             krate,
@@ -230,9 +230,6 @@ pub fn register_plugins<'a>(
         }
     });
 
-    let lint_store = Lrc::new(lint_store);
-    sess.init_lint_store(lint_store.clone());
-
     Ok((krate, lint_store))
 }
 
@@ -980,7 +977,7 @@ fn analysis(tcx: TyCtxt<'_>, (): ()) -> Result<()> {
 fn encode_and_write_metadata(
     tcx: TyCtxt<'_>,
     outputs: &OutputFilenames,
-) -> (middle::cstore::EncodedMetadata, bool) {
+) -> (EncodedMetadata, bool) {
     #[derive(PartialEq, Eq, PartialOrd, Ord)]
     enum MetadataKind {
         None,
@@ -1003,8 +1000,8 @@ fn encode_and_write_metadata(
         .unwrap_or(MetadataKind::None);
 
     let metadata = match metadata_kind {
-        MetadataKind::None => middle::cstore::EncodedMetadata::new(),
-        MetadataKind::Uncompressed | MetadataKind::Compressed => tcx.encode_metadata(),
+        MetadataKind::None => EncodedMetadata::new(),
+        MetadataKind::Uncompressed | MetadataKind::Compressed => encode_metadata(tcx),
     };
 
     let _prof_timer = tcx.sess.prof.generic_activity("write_crate_metadata");
@@ -1023,7 +1020,7 @@ fn encode_and_write_metadata(
             .tempdir_in(out_filename.parent().unwrap())
             .unwrap_or_else(|err| tcx.sess.fatal(&format!("couldn't create a temp dir: {}", err)));
         let metadata_tmpdir = MaybeTempDir::new(metadata_tmpdir, tcx.sess.opts.cg.save_temps);
-        let metadata_filename = emit_metadata(tcx.sess, &metadata.raw_data, &metadata_tmpdir);
+        let metadata_filename = emit_metadata(tcx.sess, metadata.raw_data(), &metadata_tmpdir);
         if let Err(e) = util::non_durable_rename(&metadata_filename, &out_filename) {
             tcx.sess.fatal(&format!("failed to write {}: {}", out_filename.display(), e));
         }
diff --git a/compiler/rustc_interface/src/queries.rs b/compiler/rustc_interface/src/queries.rs
index 2f540395b2d..a71b59b9d49 100644
--- a/compiler/rustc_interface/src/queries.rs
+++ b/compiler/rustc_interface/src/queries.rs
@@ -135,7 +135,7 @@ impl<'tcx> Queries<'tcx> {
             let krate = self.parse()?.take();
 
             let empty: &(dyn Fn(&Session, &mut LintStore) + Sync + Send) = &|_, _| {};
-            let result = passes::register_plugins(
+            let (krate, lint_store) = passes::register_plugins(
                 self.session(),
                 &*self.codegen_backend().metadata_loader(),
                 self.compiler.register_lints.as_deref().unwrap_or_else(|| empty),
@@ -150,7 +150,7 @@ impl<'tcx> Queries<'tcx> {
             // called, which happens within passes::register_plugins().
             self.dep_graph_future().ok();
 
-            Ok(result)
+            Ok((krate, Lrc::new(lint_store)))
         })
     }
 
diff --git a/compiler/rustc_lint/src/context.rs b/compiler/rustc_lint/src/context.rs
index 8cbd2ddcbfd..d235b220944 100644
--- a/compiler/rustc_lint/src/context.rs
+++ b/compiler/rustc_lint/src/context.rs
@@ -38,7 +38,6 @@ use rustc_serialize::json::Json;
 use rustc_session::lint::{BuiltinLintDiagnostics, ExternDepSpec};
 use rustc_session::lint::{FutureIncompatibleInfo, Level, Lint, LintBuffer, LintId};
 use rustc_session::Session;
-use rustc_session::SessionLintStore;
 use rustc_span::lev_distance::find_best_match_for_name;
 use rustc_span::{symbol::Symbol, MultiSpan, Span, DUMMY_SP};
 use rustc_target::abi;
@@ -75,20 +74,6 @@ pub struct LintStore {
     lint_groups: FxHashMap<&'static str, LintGroup>,
 }
 
-impl SessionLintStore for LintStore {
-    fn name_to_lint(&self, lint_name: &str) -> LintId {
-        let lints = self
-            .find_lints(lint_name)
-            .unwrap_or_else(|_| panic!("Failed to find lint with name `{}`", lint_name));
-
-        if let &[lint] = lints.as_slice() {
-            return lint;
-        } else {
-            panic!("Found mutliple lints with name `{}`: {:?}", lint_name, lints);
-        }
-    }
-}
-
 /// The target of the `by_name` map, which accounts for renaming/deprecation.
 #[derive(Debug)]
 enum TargetLint {
diff --git a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
index 48eb50953a9..ddb5f7dcebf 100644
--- a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
@@ -1572,7 +1572,11 @@ extern "C" bool
 LLVMRustPrepareThinLTOResolveWeak(const LLVMRustThinLTOData *Data, LLVMModuleRef M) {
   Module &Mod = *unwrap(M);
   const auto &DefinedGlobals = Data->ModuleToDefinedGVSummaries.lookup(Mod.getModuleIdentifier());
+#if LLVM_VERSION_GE(14, 0)
+  thinLTOFinalizeInModule(Mod, DefinedGlobals, /*PropagateAttrs=*/true);
+#else
   thinLTOResolvePrevailingInModule(Mod, DefinedGlobals);
+#endif
   return true;
 }
 
diff --git a/compiler/rustc_metadata/src/lib.rs b/compiler/rustc_metadata/src/lib.rs
index 2c9bad7e5ce..644b849a9f8 100644
--- a/compiler/rustc_metadata/src/lib.rs
+++ b/compiler/rustc_metadata/src/lib.rs
@@ -30,4 +30,4 @@ pub mod creader;
 pub mod dynamic_lib;
 pub mod locator;
 
-pub use rmeta::METADATA_HEADER;
+pub use rmeta::{encode_metadata, EncodedMetadata, METADATA_HEADER};
diff --git a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
index 7be0e32ef38..bd1d99640f8 100644
--- a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
+++ b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
@@ -1,7 +1,6 @@
 use crate::creader::{CStore, LoadedMacro};
 use crate::foreign_modules;
 use crate::native_libs;
-use crate::rmeta::encoder;
 
 use rustc_ast as ast;
 use rustc_data_structures::stable_map::FxHashMap;
@@ -10,7 +9,7 @@ use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, CRATE_DEF_INDEX, LOCAL_CRATE}
 use rustc_hir::definitions::{DefKey, DefPath, DefPathHash};
 use rustc_middle::hir::exports::Export;
 use rustc_middle::middle::cstore::ForeignModule;
-use rustc_middle::middle::cstore::{CrateSource, CrateStore, EncodedMetadata};
+use rustc_middle::middle::cstore::{CrateSource, CrateStore};
 use rustc_middle::middle::exported_symbols::ExportedSymbol;
 use rustc_middle::middle::stability::DeprecationEntry;
 use rustc_middle::ty::query::Providers;
@@ -511,8 +510,4 @@ impl CrateStore for CStore {
     fn expn_hash_to_expn_id(&self, cnum: CrateNum, index_guess: u32, hash: ExpnHash) -> ExpnId {
         self.get_crate_data(cnum).expn_hash_to_expn_id(index_guess, hash)
     }
-
-    fn encode_metadata(&self, tcx: TyCtxt<'_>) -> EncodedMetadata {
-        encoder::encode_metadata(tcx)
-    }
 }
diff --git a/compiler/rustc_metadata/src/rmeta/encoder.rs b/compiler/rustc_metadata/src/rmeta/encoder.rs
index 8509aa00bc0..1e3bf8aca8b 100644
--- a/compiler/rustc_metadata/src/rmeta/encoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/encoder.rs
@@ -18,7 +18,7 @@ use rustc_hir::{AnonConst, GenericParamKind};
 use rustc_index::bit_set::GrowableBitSet;
 use rustc_index::vec::Idx;
 use rustc_middle::hir::map::Map;
-use rustc_middle::middle::cstore::{EncodedMetadata, ForeignModule, LinkagePreference, NativeLib};
+use rustc_middle::middle::cstore::{ForeignModule, LinkagePreference, NativeLib};
 use rustc_middle::middle::dependency_format::Linkage;
 use rustc_middle::middle::exported_symbols::{
     metadata_symbol_name, ExportedSymbol, SymbolExportLevel,
@@ -2101,7 +2101,26 @@ fn prefetch_mir(tcx: TyCtxt<'_>) {
 // will allow us to slice the metadata to the precise length that we just
 // generated regardless of trailing bytes that end up in it.
 
-pub(super) fn encode_metadata(tcx: TyCtxt<'_>) -> EncodedMetadata {
+#[derive(Encodable, Decodable)]
+pub struct EncodedMetadata {
+    raw_data: Vec<u8>,
+}
+
+impl EncodedMetadata {
+    #[inline]
+    pub fn new() -> EncodedMetadata {
+        EncodedMetadata { raw_data: Vec::new() }
+    }
+
+    #[inline]
+    pub fn raw_data(&self) -> &[u8] {
+        &self.raw_data[..]
+    }
+}
+
+pub fn encode_metadata(tcx: TyCtxt<'_>) -> EncodedMetadata {
+    let _prof_timer = tcx.prof.verbose_generic_activity("generate_crate_metadata");
+
     // Since encoding metadata is not in a query, and nothing is cached,
     // there's no need to do dep-graph tracking for any of it.
     tcx.dep_graph.assert_ignored();
diff --git a/compiler/rustc_metadata/src/rmeta/mod.rs b/compiler/rustc_metadata/src/rmeta/mod.rs
index eb2bd80f46e..af06e1cf3f9 100644
--- a/compiler/rustc_metadata/src/rmeta/mod.rs
+++ b/compiler/rustc_metadata/src/rmeta/mod.rs
@@ -33,6 +33,7 @@ use decoder::DecodeContext;
 pub use decoder::{provide, provide_extern};
 crate use decoder::{CrateMetadata, CrateNumMap, MetadataBlob};
 use encoder::EncodeContext;
+pub use encoder::{encode_metadata, EncodedMetadata};
 use rustc_span::hygiene::SyntaxContextData;
 
 mod decoder;
diff --git a/compiler/rustc_middle/Cargo.toml b/compiler/rustc_middle/Cargo.toml
index b1fcc34bee1..d06c593d394 100644
--- a/compiler/rustc_middle/Cargo.toml
+++ b/compiler/rustc_middle/Cargo.toml
@@ -32,3 +32,5 @@ chalk-ir = "0.55.0"
 smallvec = { version = "1.6.1", features = ["union", "may_dangle"] }
 rustc_session = { path = "../rustc_session" }
 rustc_type_ir = { path = "../rustc_type_ir" }
+rand = "0.8.4"
+rand_xoshiro = "0.6.0"
diff --git a/compiler/rustc_middle/src/middle/cstore.rs b/compiler/rustc_middle/src/middle/cstore.rs
index 81c44b27033..2a1bb43a466 100644
--- a/compiler/rustc_middle/src/middle/cstore.rs
+++ b/compiler/rustc_middle/src/middle/cstore.rs
@@ -2,8 +2,6 @@
 //! are *mostly* used as a part of that interface, but these should
 //! probably get a better home if someone can find one.
 
-use crate::ty::TyCtxt;
-
 use rustc_ast as ast;
 use rustc_data_structures::sync::{self, MetadataRef};
 use rustc_hir::def_id::{CrateNum, DefId, StableCrateId, LOCAL_CRATE};
@@ -150,17 +148,6 @@ pub enum ExternCrateSource {
     Path,
 }
 
-#[derive(Encodable, Decodable)]
-pub struct EncodedMetadata {
-    pub raw_data: Vec<u8>,
-}
-
-impl EncodedMetadata {
-    pub fn new() -> EncodedMetadata {
-        EncodedMetadata { raw_data: Vec::new() }
-    }
-}
-
 /// The backend's way to give the crate store access to the metadata in a library.
 /// Note that it returns the raw metadata bytes stored in the library file, whether
 /// it is compressed, uncompressed, some weird mix, etc.
@@ -204,9 +191,6 @@ pub trait CrateStore: std::fmt::Debug {
     /// Fetch a DefId from a DefPathHash for a foreign crate.
     fn def_path_hash_to_def_id(&self, cnum: CrateNum, hash: DefPathHash) -> DefId;
     fn expn_hash_to_expn_id(&self, cnum: CrateNum, index_guess: u32, hash: ExpnHash) -> ExpnId;
-
-    // utility functions
-    fn encode_metadata(&self, tcx: TyCtxt<'_>) -> EncodedMetadata;
 }
 
 pub type CrateStoreDyn = dyn CrateStore + sync::Sync;
diff --git a/compiler/rustc_middle/src/middle/stability.rs b/compiler/rustc_middle/src/middle/stability.rs
index f0b4b6b5a0c..597622b2ebf 100644
--- a/compiler/rustc_middle/src/middle/stability.rs
+++ b/compiler/rustc_middle/src/middle/stability.rs
@@ -15,12 +15,11 @@ use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, CRATE_DEF_INDEX};
 use rustc_hir::{self, HirId};
 use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_session::lint::builtin::{DEPRECATED, DEPRECATED_IN_FUTURE, SOFT_UNSTABLE};
-use rustc_session::lint::{BuiltinLintDiagnostics, Lint, LintBuffer};
+use rustc_session::lint::{BuiltinLintDiagnostics, Level, Lint, LintBuffer};
 use rustc_session::parse::feature_err_issue;
 use rustc_session::{DiagnosticMessageId, Session};
 use rustc_span::symbol::{sym, Symbol};
 use rustc_span::{MultiSpan, Span};
-
 use std::num::NonZeroU32;
 
 #[derive(PartialEq, Clone, Copy, Debug)]
@@ -125,7 +124,11 @@ pub fn report_unstable(
 
 /// Checks whether an item marked with `deprecated(since="X")` is currently
 /// deprecated (i.e., whether X is not greater than the current rustc version).
-pub fn deprecation_in_effect(is_since_rustc_version: bool, since: Option<&str>) -> bool {
+pub fn deprecation_in_effect(depr: &Deprecation) -> bool {
+    let is_since_rustc_version = depr.is_since_rustc_version;
+    let since = depr.since.map(Symbol::as_str);
+    let since = since.as_deref();
+
     fn parse_version(ver: &str) -> Vec<u32> {
         // We ignore non-integer components of the version (e.g., "nightly").
         ver.split(|c| c == '.' || c == '-').flat_map(|s| s.parse()).collect()
@@ -175,33 +178,50 @@ pub fn deprecation_suggestion(
     }
 }
 
-pub fn deprecation_message(depr: &Deprecation, kind: &str, path: &str) -> (String, &'static Lint) {
-    let since = depr.since.map(Symbol::as_str);
-    let (message, lint) = if deprecation_in_effect(depr.is_since_rustc_version, since.as_deref()) {
-        (format!("use of deprecated {} `{}`", kind, path), DEPRECATED)
+fn deprecation_lint(is_in_effect: bool) -> &'static Lint {
+    if is_in_effect { DEPRECATED } else { DEPRECATED_IN_FUTURE }
+}
+
+fn deprecation_message(
+    is_in_effect: bool,
+    since: Option<Symbol>,
+    note: Option<Symbol>,
+    kind: &str,
+    path: &str,
+) -> String {
+    let message = if is_in_effect {
+        format!("use of deprecated {} `{}`", kind, path)
     } else {
-        (
-            if since.as_deref() == Some("TBD") {
-                format!(
-                    "use of {} `{}` that will be deprecated in a future Rust version",
-                    kind, path
-                )
-            } else {
-                format!(
-                    "use of {} `{}` that will be deprecated in future version {}",
-                    kind,
-                    path,
-                    since.unwrap()
-                )
-            },
-            DEPRECATED_IN_FUTURE,
-        )
+        let since = since.map(Symbol::as_str);
+
+        if since.as_deref() == Some("TBD") {
+            format!("use of {} `{}` that will be deprecated in a future Rust version", kind, path)
+        } else {
+            format!(
+                "use of {} `{}` that will be deprecated in future version {}",
+                kind,
+                path,
+                since.unwrap()
+            )
+        }
     };
-    let message = match depr.note {
+
+    match note {
         Some(reason) => format!("{}: {}", message, reason),
         None => message,
-    };
-    (message, lint)
+    }
+}
+
+pub fn deprecation_message_and_lint(
+    depr: &Deprecation,
+    kind: &str,
+    path: &str,
+) -> (String, &'static Lint) {
+    let is_in_effect = deprecation_in_effect(depr);
+    (
+        deprecation_message(is_in_effect, depr.since, depr.note, kind, path),
+        deprecation_lint(is_in_effect),
+    )
 }
 
 pub fn early_report_deprecation(
@@ -303,20 +323,34 @@ impl<'tcx> TyCtxt<'tcx> {
                 //
                 // #[rustc_deprecated] however wants to emit down the whole
                 // hierarchy.
-                if !skip || depr_entry.attr.is_since_rustc_version {
-                    let path = &with_no_trimmed_paths(|| self.def_path_str(def_id));
-                    let kind = self.def_kind(def_id).descr(def_id);
-                    let (message, lint) = deprecation_message(&depr_entry.attr, kind, path);
-                    late_report_deprecation(
-                        self,
-                        &message,
-                        depr_entry.attr.suggestion,
-                        lint,
-                        span,
-                        method_span,
-                        id,
-                        def_id,
-                    );
+                let depr_attr = &depr_entry.attr;
+                if !skip || depr_attr.is_since_rustc_version {
+                    // Calculating message for lint involves calling `self.def_path_str`.
+                    // Which by default to calculate visible path will invoke expensive `visible_parent_map` query.
+                    // So we skip message calculation altogether, if lint is allowed.
+                    let is_in_effect = deprecation_in_effect(depr_attr);
+                    let lint = deprecation_lint(is_in_effect);
+                    if self.lint_level_at_node(lint, id).0 != Level::Allow {
+                        let def_path = &with_no_trimmed_paths(|| self.def_path_str(def_id));
+                        let def_kind = self.def_kind(def_id).descr(def_id);
+
+                        late_report_deprecation(
+                            self,
+                            &deprecation_message(
+                                is_in_effect,
+                                depr_attr.since,
+                                depr_attr.note,
+                                def_kind,
+                                def_path,
+                            ),
+                            depr_attr.suggestion,
+                            lint,
+                            span,
+                            method_span,
+                            id,
+                            def_id,
+                        );
+                    }
                 }
             };
         }
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 72b8d7cce71..1e8ae813336 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -7,7 +7,6 @@ use crate::ich::{NodeIdHashingMode, StableHashingContext};
 use crate::infer::canonical::{Canonical, CanonicalVarInfo, CanonicalVarInfos};
 use crate::lint::{struct_lint_level, LintDiagnosticBuilder, LintLevelSource};
 use crate::middle;
-use crate::middle::cstore::EncodedMetadata;
 use crate::middle::resolve_lifetime::{self, LifetimeScopeForPath, ObjectLifetimeDefault};
 use crate::middle::stability;
 use crate::mir::interpret::{self, AllocId, Allocation, ConstValue, Scalar};
@@ -1324,11 +1323,6 @@ impl<'tcx> TyCtxt<'tcx> {
         )
     }
 
-    pub fn encode_metadata(self) -> EncodedMetadata {
-        let _prof_timer = self.prof.verbose_generic_activity("generate_crate_metadata");
-        self.untracked_resolutions.cstore.encode_metadata(self)
-    }
-
     /// Note that this is *untracked* and should only be used within the query
     /// system if the result is otherwise tracked through queries
     pub fn cstore_untracked(self) -> &'tcx ty::CrateStoreDyn {
diff --git a/compiler/rustc_middle/src/ty/fold.rs b/compiler/rustc_middle/src/ty/fold.rs
index a04b0a7ef61..e16491dcc90 100644
--- a/compiler/rustc_middle/src/ty/fold.rs
+++ b/compiler/rustc_middle/src/ty/fold.rs
@@ -79,6 +79,7 @@ pub trait TypeFoldable<'tcx>: fmt::Debug + Clone {
             == Some(FoundFlags)
     }
 
+    #[instrument(level = "trace")]
     fn has_type_flags(&self, flags: TypeFlags) -> bool {
         self.visit_with(&mut HasTypeFlagsVisitor { tcx: None, flags }).break_value()
             == Some(FoundFlags)
@@ -476,21 +477,16 @@ impl<'a, 'tcx> TypeFolder<'tcx> for RegionFolder<'a, 'tcx> {
         t
     }
 
+    #[instrument(skip(self), level = "debug")]
     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
         match *r {
             ty::ReLateBound(debruijn, _) if debruijn < self.current_index => {
-                debug!(
-                    "RegionFolder.fold_region({:?}) skipped bound region (current index={:?})",
-                    r, self.current_index
-                );
+                debug!(?self.current_index, "skipped bound region");
                 *self.skipped_regions = true;
                 r
             }
             _ => {
-                debug!(
-                    "RegionFolder.fold_region({:?}) folding free region (current_index={:?})",
-                    r, self.current_index
-                );
+                debug!(?self.current_index, "folding free region");
                 (self.fold_region_fn)(r, self.current_index)
             }
         }
@@ -1125,6 +1121,12 @@ struct HasTypeFlagsVisitor<'tcx> {
     flags: ty::TypeFlags,
 }
 
+impl std::fmt::Debug for HasTypeFlagsVisitor<'tcx> {
+    fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.flags.fmt(fmt)
+    }
+}
+
 impl<'tcx> TypeVisitor<'tcx> for HasTypeFlagsVisitor<'tcx> {
     type BreakTy = FoundFlags;
     fn tcx_for_anon_const_substs(&self) -> Option<TyCtxt<'tcx>> {
@@ -1132,9 +1134,10 @@ impl<'tcx> TypeVisitor<'tcx> for HasTypeFlagsVisitor<'tcx> {
     }
 
     #[inline]
+    #[instrument(level = "trace")]
     fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
         let flags = t.flags();
-        debug!("HasTypeFlagsVisitor: t={:?} flags={:?} self.flags={:?}", t, flags, self.flags);
+        trace!(t.flags=?t.flags());
         if flags.intersects(self.flags) {
             ControlFlow::Break(FoundFlags)
         } else {
@@ -1146,9 +1149,10 @@ impl<'tcx> TypeVisitor<'tcx> for HasTypeFlagsVisitor<'tcx> {
     }
 
     #[inline]
+    #[instrument(skip(self), level = "trace")]
     fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
         let flags = r.type_flags();
-        debug!("HasTypeFlagsVisitor: r={:?} r.flags={:?} self.flags={:?}", r, flags, self.flags);
+        trace!(r.flags=?flags);
         if flags.intersects(self.flags) {
             ControlFlow::Break(FoundFlags)
         } else {
@@ -1157,9 +1161,10 @@ impl<'tcx> TypeVisitor<'tcx> for HasTypeFlagsVisitor<'tcx> {
     }
 
     #[inline]
+    #[instrument(level = "trace")]
     fn visit_const(&mut self, c: &'tcx ty::Const<'tcx>) -> ControlFlow<Self::BreakTy> {
         let flags = FlagComputation::for_const(c);
-        debug!("HasTypeFlagsVisitor: c={:?} c.flags={:?} self.flags={:?}", c, flags, self.flags);
+        trace!(r.flags=?flags);
         if flags.intersects(self.flags) {
             ControlFlow::Break(FoundFlags)
         } else {
@@ -1171,9 +1176,10 @@ impl<'tcx> TypeVisitor<'tcx> for HasTypeFlagsVisitor<'tcx> {
     }
 
     #[inline]
+    #[instrument(level = "trace")]
     fn visit_unevaluated_const(&mut self, uv: ty::Unevaluated<'tcx>) -> ControlFlow<Self::BreakTy> {
         let flags = FlagComputation::for_unevaluated_const(uv);
-        debug!("HasTypeFlagsVisitor: uv={:?} uv.flags={:?} self.flags={:?}", uv, flags, self.flags);
+        trace!(r.flags=?flags);
         if flags.intersects(self.flags) {
             ControlFlow::Break(FoundFlags)
         } else {
@@ -1185,12 +1191,10 @@ impl<'tcx> TypeVisitor<'tcx> for HasTypeFlagsVisitor<'tcx> {
     }
 
     #[inline]
+    #[instrument(level = "trace")]
     fn visit_predicate(&mut self, predicate: ty::Predicate<'tcx>) -> ControlFlow<Self::BreakTy> {
         let flags = predicate.inner.flags;
-        debug!(
-            "HasTypeFlagsVisitor: predicate={:?} flags={:?} self.flags={:?}",
-            predicate, flags, self.flags
-        );
+        trace!(predicate.flags=?flags);
         if flags.intersects(self.flags) {
             ControlFlow::Break(FoundFlags)
         } else {
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index cfbbec374a1..b6aeb9122c3 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -24,6 +24,9 @@ use std::iter;
 use std::num::NonZeroUsize;
 use std::ops::Bound;
 
+use rand::{seq::SliceRandom, SeedableRng};
+use rand_xoshiro::Xoshiro128StarStar;
+
 pub fn provide(providers: &mut ty::query::Providers) {
     *providers =
         ty::query::Providers { layout_of, fn_abi_of_fn_ptr, fn_abi_of_instance, ..*providers };
@@ -324,6 +327,10 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
 
         let mut inverse_memory_index: Vec<u32> = (0..fields.len() as u32).collect();
 
+        // `ReprOptions.layout_seed` is a deterministic seed that we can use to
+        // randomize field ordering with
+        let mut rng = Xoshiro128StarStar::seed_from_u64(repr.field_shuffle_seed);
+
         let optimize = !repr.inhibit_struct_field_reordering_opt();
         if optimize {
             let end =
@@ -332,20 +339,35 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
             let field_align = |f: &TyAndLayout<'_>| {
                 if let Some(pack) = pack { f.align.abi.min(pack) } else { f.align.abi }
             };
-            match kind {
-                StructKind::AlwaysSized | StructKind::MaybeUnsized => {
-                    optimizing.sort_by_key(|&x| {
-                        // Place ZSTs first to avoid "interesting offsets",
-                        // especially with only one or two non-ZST fields.
-                        let f = &fields[x as usize];
-                        (!f.is_zst(), cmp::Reverse(field_align(f)))
-                    });
-                }
-                StructKind::Prefixed(..) => {
-                    // Sort in ascending alignment so that the layout stay optimal
-                    // regardless of the prefix
-                    optimizing.sort_by_key(|&x| field_align(&fields[x as usize]));
+
+            // If `-Z randomize-layout` was enabled for the type definition we can shuffle
+            // the field ordering to try and catch some code making assumptions about layouts
+            // we don't guarantee
+            if repr.can_randomize_type_layout() {
+                // Shuffle the ordering of the fields
+                optimizing.shuffle(&mut rng);
+
+            // Otherwise we just leave things alone and actually optimize the type's fields
+            } else {
+                match kind {
+                    StructKind::AlwaysSized | StructKind::MaybeUnsized => {
+                        optimizing.sort_by_key(|&x| {
+                            // Place ZSTs first to avoid "interesting offsets",
+                            // especially with only one or two non-ZST fields.
+                            let f = &fields[x as usize];
+                            (!f.is_zst(), cmp::Reverse(field_align(f)))
+                        });
+                    }
+
+                    StructKind::Prefixed(..) => {
+                        // Sort in ascending alignment so that the layout stays optimal
+                        // regardless of the prefix
+                        optimizing.sort_by_key(|&x| field_align(&fields[x as usize]));
+                    }
                 }
+
+                // FIXME(Kixiron): We can always shuffle fields within a given alignment class
+                //                 regardless of the status of `-Z randomize-layout`
             }
         }
 
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index b3ae76d9871..d04d1565fea 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -1491,6 +1491,9 @@ bitflags! {
         const IS_LINEAR          = 1 << 3;
         // If true, don't expose any niche to type's context.
         const HIDE_NICHE         = 1 << 4;
+        // If true, the type's layout can be randomized using
+        // the seed stored in `ReprOptions.layout_seed`
+        const RANDOMIZE_LAYOUT   = 1 << 5;
         // Any of these flags being set prevent field reordering optimisation.
         const IS_UNOPTIMISABLE   = ReprFlags::IS_C.bits |
                                    ReprFlags::IS_SIMD.bits |
@@ -1505,6 +1508,14 @@ pub struct ReprOptions {
     pub align: Option<Align>,
     pub pack: Option<Align>,
     pub flags: ReprFlags,
+    /// The seed to be used for randomizing a type's layout
+    ///
+    /// Note: This could technically be a `[u8; 16]` (a `u128`) which would
+    /// be the "most accurate" hash as it'd encompass the item and crate
+    /// hash without loss, but it does pay the price of being larger.
+    /// Everything's a tradeoff, a `u64` seed should be sufficient for our
+    /// purposes (primarily `-Z randomize-layout`)
+    pub field_shuffle_seed: u64,
 }
 
 impl ReprOptions {
@@ -1513,6 +1524,11 @@ impl ReprOptions {
         let mut size = None;
         let mut max_align: Option<Align> = None;
         let mut min_pack: Option<Align> = None;
+
+        // Generate a deterministically-derived seed from the item's path hash
+        // to allow for cross-crate compilation to actually work
+        let field_shuffle_seed = tcx.def_path_hash(did).0.to_smaller_hash();
+
         for attr in tcx.get_attrs(did).iter() {
             for r in attr::find_repr_attrs(&tcx.sess, attr) {
                 flags.insert(match r {
@@ -1541,33 +1557,45 @@ impl ReprOptions {
             }
         }
 
+        // If `-Z randomize-layout` was enabled for the type definition then we can
+        // consider performing layout randomization
+        if tcx.sess.opts.debugging_opts.randomize_layout {
+            flags.insert(ReprFlags::RANDOMIZE_LAYOUT);
+        }
+
         // This is here instead of layout because the choice must make it into metadata.
         if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
             flags.insert(ReprFlags::IS_LINEAR);
         }
-        ReprOptions { int: size, align: max_align, pack: min_pack, flags }
+
+        Self { int: size, align: max_align, pack: min_pack, flags, field_shuffle_seed }
     }
 
     #[inline]
     pub fn simd(&self) -> bool {
         self.flags.contains(ReprFlags::IS_SIMD)
     }
+
     #[inline]
     pub fn c(&self) -> bool {
         self.flags.contains(ReprFlags::IS_C)
     }
+
     #[inline]
     pub fn packed(&self) -> bool {
         self.pack.is_some()
     }
+
     #[inline]
     pub fn transparent(&self) -> bool {
         self.flags.contains(ReprFlags::IS_TRANSPARENT)
     }
+
     #[inline]
     pub fn linear(&self) -> bool {
         self.flags.contains(ReprFlags::IS_LINEAR)
     }
+
     #[inline]
     pub fn hide_niche(&self) -> bool {
         self.flags.contains(ReprFlags::HIDE_NICHE)
@@ -1594,9 +1622,17 @@ impl ReprOptions {
                 return true;
             }
         }
+
         self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
     }
 
+    /// Returns `true` if this type is valid for reordering and `-Z randomize-layout`
+    /// was enabled for its declaration crate
+    pub fn can_randomize_type_layout(&self) -> bool {
+        !self.inhibit_struct_field_reordering_opt()
+            && self.flags.contains(ReprFlags::RANDOMIZE_LAYOUT)
+    }
+
     /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
     pub fn inhibit_union_abi_opt(&self) -> bool {
         self.c()
diff --git a/compiler/rustc_middle/src/ty/print/mod.rs b/compiler/rustc_middle/src/ty/print/mod.rs
index 13e2122a619..308b4d2fefc 100644
--- a/compiler/rustc_middle/src/ty/print/mod.rs
+++ b/compiler/rustc_middle/src/ty/print/mod.rs
@@ -98,14 +98,14 @@ pub trait Printer<'tcx>: Sized {
 
     // Defaults (should not be overridden):
 
+    #[instrument(skip(self), level = "debug")]
     fn default_print_def_path(
         self,
         def_id: DefId,
         substs: &'tcx [GenericArg<'tcx>],
     ) -> Result<Self::Path, Self::Error> {
-        debug!("default_print_def_path: def_id={:?}, substs={:?}", def_id, substs);
         let key = self.tcx().def_key(def_id);
-        debug!("default_print_def_path: key={:?}", key);
+        debug!(?key);
 
         match key.disambiguated_data.data {
             DefPathData::CrateRoot => {
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index d99534c200a..b8bca6363db 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -2033,12 +2033,11 @@ impl<F: fmt::Write> FmtPrinter<'_, 'tcx, F> {
         Ok(inner)
     }
 
+    #[instrument(skip(self), level = "debug")]
     fn prepare_late_bound_region_info<T>(&mut self, value: &ty::Binder<'tcx, T>)
     where
         T: TypeFoldable<'tcx>,
     {
-        debug!("prepare_late_bound_region_info(value: {:?})", value);
-
         struct LateBoundRegionNameCollector<'a, 'tcx> {
             tcx: TyCtxt<'tcx>,
             used_region_names: &'a mut FxHashSet<Symbol>,
@@ -2052,8 +2051,9 @@ impl<F: fmt::Write> FmtPrinter<'_, 'tcx, F> {
                 Some(self.tcx)
             }
 
+            #[instrument(skip(self), level = "trace")]
             fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
-                debug!("LateBoundRegionNameCollector::visit_region(r: {:?}, address: {:p})", r, &r);
+                trace!("address: {:p}", r);
                 if let ty::ReLateBound(_, ty::BoundRegion { kind: ty::BrNamed(_, name), .. }) = *r {
                     self.used_region_names.insert(name);
                 } else if let ty::RePlaceholder(ty::PlaceholderRegion {
@@ -2068,8 +2068,8 @@ impl<F: fmt::Write> FmtPrinter<'_, 'tcx, F> {
 
             // We collect types in order to prevent really large types from compiling for
             // a really long time. See issue #83150 for why this is necessary.
+            #[instrument(skip(self), level = "trace")]
             fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
-                debug!("LateBoundRegionNameCollector::visit_ty(ty: {:?}", ty);
                 let not_previously_inserted = self.type_collector.insert(ty);
                 if not_previously_inserted {
                     ty.super_visit_with(self)
diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs
index 2ec06d472fe..d4032cdf696 100644
--- a/compiler/rustc_middle/src/ty/util.rs
+++ b/compiler/rustc_middle/src/ty/util.rs
@@ -516,6 +516,7 @@ impl<'tcx> TyCtxt<'tcx> {
     }
 
     /// Expands the given impl trait type, stopping if the type is recursive.
+    #[instrument(skip(self), level = "debug")]
     pub fn try_expand_impl_trait_type(
         self,
         def_id: DefId,
@@ -532,6 +533,7 @@ impl<'tcx> TyCtxt<'tcx> {
         };
 
         let expanded_type = visitor.expand_opaque_ty(def_id, substs).unwrap();
+        trace!(?expanded_type);
         if visitor.found_recursion { Err(expanded_type) } else { Ok(expanded_type) }
     }
 }
diff --git a/compiler/rustc_mir_build/src/build/expr/into.rs b/compiler/rustc_mir_build/src/build/expr/into.rs
index 1803a18441c..53868f28557 100644
--- a/compiler/rustc_mir_build/src/build/expr/into.rs
+++ b/compiler/rustc_mir_build/src/build/expr/into.rs
@@ -449,8 +449,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     })
                     .collect();
 
-                let destination = this.cfg.start_new_block();
+                if !options.contains(InlineAsmOptions::NORETURN) {
+                    this.cfg.push_assign_unit(block, source_info, destination, this.tcx);
+                }
 
+                let destination_block = this.cfg.start_new_block();
                 this.cfg.terminate(
                     block,
                     source_info,
@@ -462,11 +465,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         destination: if options.contains(InlineAsmOptions::NORETURN) {
                             None
                         } else {
-                            Some(destination)
+                            Some(destination_block)
                         },
                     },
                 );
-                destination.unit()
+                destination_block.unit()
             }
 
             // These cases don't actually need a destination
diff --git a/compiler/rustc_mir_build/src/thir/cx/expr.rs b/compiler/rustc_mir_build/src/thir/cx/expr.rs
index 66005be05df..17296a95bc1 100644
--- a/compiler/rustc_mir_build/src/thir/cx/expr.rs
+++ b/compiler/rustc_mir_build/src/thir/cx/expr.rs
@@ -39,10 +39,17 @@ impl<'tcx> Cx<'tcx> {
 
         let mut expr = self.make_mirror_unadjusted(hir_expr);
 
+        let adjustment_span = match self.adjustment_span {
+            Some((hir_id, span)) if hir_id == hir_expr.hir_id => Some(span),
+            _ => None,
+        };
+
         // Now apply adjustments, if any.
         for adjustment in self.typeck_results.expr_adjustments(hir_expr) {
             debug!("make_mirror: expr={:?} applying adjustment={:?}", expr, adjustment);
-            expr = self.apply_adjustment(hir_expr, expr, adjustment);
+            let span = expr.span;
+            expr =
+                self.apply_adjustment(hir_expr, expr, adjustment, adjustment_span.unwrap_or(span));
         }
 
         // Next, wrap this up in the expr's scope.
@@ -82,8 +89,9 @@ impl<'tcx> Cx<'tcx> {
         hir_expr: &'tcx hir::Expr<'tcx>,
         mut expr: Expr<'tcx>,
         adjustment: &Adjustment<'tcx>,
+        mut span: Span,
     ) -> Expr<'tcx> {
-        let Expr { temp_lifetime, mut span, .. } = expr;
+        let Expr { temp_lifetime, .. } = expr;
 
         // Adjust the span from the block, to the last expression of the
         // block. This is a better span when returning a mutable reference
@@ -150,6 +158,7 @@ impl<'tcx> Cx<'tcx> {
 
     fn make_mirror_unadjusted(&mut self, expr: &'tcx hir::Expr<'tcx>) -> Expr<'tcx> {
         let expr_ty = self.typeck_results().expr_ty(expr);
+        let expr_span = expr.span;
         let temp_lifetime = self.region_scope_tree.temporary_scope(expr.hir_id.local_id);
 
         let kind = match expr.kind {
@@ -157,7 +166,13 @@ impl<'tcx> Cx<'tcx> {
             hir::ExprKind::MethodCall(_, method_span, ref args, fn_span) => {
                 // Rewrite a.b(c) into UFCS form like Trait::b(a, c)
                 let expr = self.method_callee(expr, method_span, None);
+                // When we apply adjustments to the receiver, use the span of
+                // the overall method call for better diagnostics. args[0]
+                // is guaranteed to exist, since a method call always has a receiver.
+                let old_adjustment_span = self.adjustment_span.replace((args[0].hir_id, expr_span));
+                tracing::info!("Using method span: {:?}", expr.span);
                 let args = self.mirror_exprs(args);
+                self.adjustment_span = old_adjustment_span;
                 ExprKind::Call {
                     ty: expr.ty,
                     fun: self.thir.exprs.push(expr),
diff --git a/compiler/rustc_mir_build/src/thir/cx/mod.rs b/compiler/rustc_mir_build/src/thir/cx/mod.rs
index 5059dd939d9..38a4676bd15 100644
--- a/compiler/rustc_mir_build/src/thir/cx/mod.rs
+++ b/compiler/rustc_mir_build/src/thir/cx/mod.rs
@@ -9,6 +9,7 @@ use rustc_ast as ast;
 use rustc_data_structures::steal::Steal;
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
+use rustc_hir::HirId;
 use rustc_hir::Node;
 use rustc_middle::middle::region;
 use rustc_middle::mir::interpret::{LitToConstError, LitToConstInput};
@@ -46,6 +47,14 @@ struct Cx<'tcx> {
     crate region_scope_tree: &'tcx region::ScopeTree,
     crate typeck_results: &'tcx ty::TypeckResults<'tcx>,
 
+    /// When applying adjustments to the expression
+    /// with the given `HirId`, use the given `Span`,
+    /// instead of the usual span. This is used to
+    /// assign the span of an overall method call
+    /// (e.g. `my_val.foo()`) to the adjustment expressions
+    /// for the receiver.
+    adjustment_span: Option<(HirId, Span)>,
+
     /// The `DefId` of the owner of this body.
     body_owner: DefId,
 }
@@ -60,6 +69,7 @@ impl<'tcx> Cx<'tcx> {
             region_scope_tree: tcx.region_scope_tree(def.did),
             typeck_results,
             body_owner: def.did.to_def_id(),
+            adjustment_span: None,
         }
     }
 
diff --git a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
index 4c51b9207bb..e28fd2c5081 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
@@ -1,6 +1,6 @@
+use super::deconstruct_pat::{Constructor, DeconstructedPat};
 use super::usefulness::{
-    compute_match_usefulness, expand_pattern, is_wildcard, MatchArm, MatchCheckCtxt, Reachability,
-    UsefulnessReport,
+    compute_match_usefulness, MatchArm, MatchCheckCtxt, Reachability, UsefulnessReport,
 };
 use super::{PatCtxt, PatternError};
 
@@ -12,14 +12,12 @@ use rustc_hir::def::*;
 use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
 use rustc_hir::{HirId, Pat};
-use rustc_middle::thir::PatKind;
-use rustc_middle::ty::{self, Ty, TyCtxt};
+use rustc_middle::ty::{self, AdtDef, Ty, TyCtxt};
 use rustc_session::lint::builtin::{
     BINDINGS_WITH_VARIANT_NAME, IRREFUTABLE_LET_PATTERNS, UNREACHABLE_PATTERNS,
 };
 use rustc_session::Session;
 use rustc_span::{DesugaringKind, ExpnKind, Span};
-use std::slice;
 
 crate fn check_match(tcx: TyCtxt<'_>, def_id: DefId) {
     let body_id = match def_id.as_local() {
@@ -27,11 +25,12 @@ crate fn check_match(tcx: TyCtxt<'_>, def_id: DefId) {
         Some(id) => tcx.hir().body_owned_by(tcx.hir().local_def_id_to_hir_id(id)),
     };
 
+    let pattern_arena = TypedArena::default();
     let mut visitor = MatchVisitor {
         tcx,
         typeck_results: tcx.typeck_body(body_id),
         param_env: tcx.param_env(def_id),
-        pattern_arena: TypedArena::default(),
+        pattern_arena: &pattern_arena,
     };
     visitor.visit_body(tcx.hir().body(body_id));
 }
@@ -40,14 +39,21 @@ fn create_e0004(sess: &Session, sp: Span, error_message: String) -> DiagnosticBu
     struct_span_err!(sess, sp, E0004, "{}", &error_message)
 }
 
-struct MatchVisitor<'a, 'tcx> {
+#[derive(PartialEq)]
+enum RefutableFlag {
+    Irrefutable,
+    Refutable,
+}
+use RefutableFlag::*;
+
+struct MatchVisitor<'a, 'p, 'tcx> {
     tcx: TyCtxt<'tcx>,
     typeck_results: &'a ty::TypeckResults<'tcx>,
     param_env: ty::ParamEnv<'tcx>,
-    pattern_arena: TypedArena<super::Pat<'tcx>>,
+    pattern_arena: &'p TypedArena<DeconstructedPat<'p, 'tcx>>,
 }
 
-impl<'tcx> Visitor<'tcx> for MatchVisitor<'_, 'tcx> {
+impl<'tcx> Visitor<'tcx> for MatchVisitor<'_, '_, 'tcx> {
     type Map = intravisit::ErasedMap<'tcx>;
 
     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
@@ -74,13 +80,13 @@ impl<'tcx> Visitor<'tcx> for MatchVisitor<'_, 'tcx> {
             hir::LocalSource::AssignDesugar(_) => ("destructuring assignment binding", None),
         };
         self.check_irrefutable(&loc.pat, msg, sp);
-        self.check_patterns(&loc.pat);
+        self.check_patterns(&loc.pat, Irrefutable);
     }
 
     fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
         intravisit::walk_param(self, param);
         self.check_irrefutable(&param.pat, "function argument", None);
-        self.check_patterns(&param.pat);
+        self.check_patterns(&param.pat, Irrefutable);
     }
 }
 
@@ -113,31 +119,30 @@ impl PatCtxt<'_, '_> {
     }
 }
 
-impl<'tcx> MatchVisitor<'_, 'tcx> {
-    fn check_patterns(&self, pat: &Pat<'_>) {
+impl<'p, 'tcx> MatchVisitor<'_, 'p, 'tcx> {
+    fn check_patterns(&self, pat: &Pat<'_>, rf: RefutableFlag) {
         pat.walk_always(|pat| check_borrow_conflicts_in_at_patterns(self, pat));
-        check_for_bindings_named_same_as_variants(self, pat);
+        check_for_bindings_named_same_as_variants(self, pat, rf);
     }
 
-    fn lower_pattern<'p>(
+    fn lower_pattern(
         &self,
         cx: &mut MatchCheckCtxt<'p, 'tcx>,
         pat: &'tcx hir::Pat<'tcx>,
         have_errors: &mut bool,
-    ) -> (&'p super::Pat<'tcx>, Ty<'tcx>) {
+    ) -> &'p DeconstructedPat<'p, 'tcx> {
         let mut patcx = PatCtxt::new(self.tcx, self.param_env, self.typeck_results);
         patcx.include_lint_checks();
         let pattern = patcx.lower_pattern(pat);
-        let pattern_ty = pattern.ty;
-        let pattern: &_ = cx.pattern_arena.alloc(expand_pattern(pattern));
+        let pattern: &_ = cx.pattern_arena.alloc(DeconstructedPat::from_pat(cx, &pattern));
         if !patcx.errors.is_empty() {
             *have_errors = true;
             patcx.report_inlining_errors();
         }
-        (pattern, pattern_ty)
+        pattern
     }
 
-    fn new_cx(&self, hir_id: HirId) -> MatchCheckCtxt<'_, 'tcx> {
+    fn new_cx(&self, hir_id: HirId) -> MatchCheckCtxt<'p, 'tcx> {
         MatchCheckCtxt {
             tcx: self.tcx,
             param_env: self.param_env,
@@ -147,10 +152,10 @@ impl<'tcx> MatchVisitor<'_, 'tcx> {
     }
 
     fn check_let(&mut self, pat: &'tcx hir::Pat<'tcx>, expr: &hir::Expr<'_>, span: Span) {
-        self.check_patterns(pat);
+        self.check_patterns(pat, Refutable);
         let mut cx = self.new_cx(expr.hir_id);
-        let tpat = self.lower_pattern(&mut cx, pat, &mut false).0;
-        check_let_reachability(&mut cx, pat.hir_id, &tpat, span);
+        let tpat = self.lower_pattern(&mut cx, pat, &mut false);
+        check_let_reachability(&mut cx, pat.hir_id, tpat, span);
     }
 
     fn check_match(
@@ -163,11 +168,11 @@ impl<'tcx> MatchVisitor<'_, 'tcx> {
 
         for arm in arms {
             // Check the arm for some things unrelated to exhaustiveness.
-            self.check_patterns(&arm.pat);
+            self.check_patterns(&arm.pat, Refutable);
             if let Some(hir::Guard::IfLet(ref pat, _)) = arm.guard {
-                self.check_patterns(pat);
-                let tpat = self.lower_pattern(&mut cx, pat, &mut false).0;
-                check_let_reachability(&mut cx, pat.hir_id, &tpat, tpat.span);
+                self.check_patterns(pat, Refutable);
+                let tpat = self.lower_pattern(&mut cx, pat, &mut false);
+                check_let_reachability(&mut cx, pat.hir_id, tpat, tpat.span());
             }
         }
 
@@ -176,7 +181,7 @@ impl<'tcx> MatchVisitor<'_, 'tcx> {
         let arms: Vec<_> = arms
             .iter()
             .map(|hir::Arm { pat, guard, .. }| MatchArm {
-                pat: self.lower_pattern(&mut cx, pat, &mut have_errors).0,
+                pat: self.lower_pattern(&mut cx, pat, &mut have_errors),
                 hir_id: pat.hir_id,
                 has_guard: guard.is_some(),
             })
@@ -190,20 +195,16 @@ impl<'tcx> MatchVisitor<'_, 'tcx> {
         let scrut_ty = self.typeck_results.expr_ty_adjusted(scrut);
         let report = compute_match_usefulness(&cx, &arms, scrut.hir_id, scrut_ty);
 
-        report_arm_reachability(&cx, &report, |_, arm_span, arm_hir_id, catchall| {
-            match source {
-                hir::MatchSource::ForLoopDesugar | hir::MatchSource::Normal => {
-                    unreachable_pattern(cx.tcx, arm_span, arm_hir_id, catchall);
-                }
-                // Unreachable patterns in try and await expressions occur when one of
-                // the arms are an uninhabited type. Which is OK.
-                hir::MatchSource::AwaitDesugar | hir::MatchSource::TryDesugar => {}
+        match source {
+            hir::MatchSource::ForLoopDesugar | hir::MatchSource::Normal => {
+                report_arm_reachability(&cx, &report)
             }
-        });
+            // Unreachable patterns in try and await expressions occur when one of
+            // the arms are an uninhabited type. Which is OK.
+            hir::MatchSource::AwaitDesugar | hir::MatchSource::TryDesugar => {}
+        }
 
         // Check if the match is exhaustive.
-        // Note: An empty match isn't the same as an empty matrix for diagnostics purposes,
-        // since an empty matrix can occur when there are arms, if those arms all have guards.
         let is_empty_match = arms.is_empty();
         let witnesses = report.non_exhaustiveness_witnesses;
         if !witnesses.is_empty() {
@@ -214,7 +215,8 @@ impl<'tcx> MatchVisitor<'_, 'tcx> {
     fn check_irrefutable(&self, pat: &'tcx Pat<'tcx>, origin: &str, sp: Option<Span>) {
         let mut cx = self.new_cx(pat.hir_id);
 
-        let (pattern, pattern_ty) = self.lower_pattern(&mut cx, pat, &mut false);
+        let pattern = self.lower_pattern(&mut cx, pat, &mut false);
+        let pattern_ty = pattern.ty();
         let arms = vec![MatchArm { pat: pattern, hir_id: pat.hir_id, has_guard: false }];
         let report = compute_match_usefulness(&cx, &arms, pat.hir_id, pattern_ty);
 
@@ -226,7 +228,7 @@ impl<'tcx> MatchVisitor<'_, 'tcx> {
             return;
         }
 
-        let joined_patterns = joined_uncovered_patterns(&witnesses);
+        let joined_patterns = joined_uncovered_patterns(&cx, &witnesses);
         let mut err = struct_span_err!(
             self.tcx.sess,
             pat.span,
@@ -302,7 +304,11 @@ fn const_not_var(
     }
 }
 
-fn check_for_bindings_named_same_as_variants(cx: &MatchVisitor<'_, '_>, pat: &Pat<'_>) {
+fn check_for_bindings_named_same_as_variants(
+    cx: &MatchVisitor<'_, '_, '_>,
+    pat: &Pat<'_>,
+    rf: RefutableFlag,
+) {
     pat.walk_always(|p| {
         if let hir::PatKind::Binding(_, _, ident, None) = p.kind {
             if let Some(ty::BindByValue(hir::Mutability::Not)) =
@@ -315,25 +321,31 @@ fn check_for_bindings_named_same_as_variants(cx: &MatchVisitor<'_, '_>, pat: &Pa
                             variant.ident == ident && variant.ctor_kind == CtorKind::Const
                         })
                     {
+                        let variant_count = edef.variants.len();
                         cx.tcx.struct_span_lint_hir(
                             BINDINGS_WITH_VARIANT_NAME,
                             p.hir_id,
                             p.span,
                             |lint| {
                                 let ty_path = cx.tcx.def_path_str(edef.did);
-                                lint.build(&format!(
+                                let mut err = lint.build(&format!(
                                     "pattern binding `{}` is named the same as one \
-                                                of the variants of the type `{}`",
+                                                    of the variants of the type `{}`",
                                     ident, ty_path
-                                ))
-                                .code(error_code!(E0170))
-                                .span_suggestion(
-                                    p.span,
-                                    "to match on the variant, qualify the path",
-                                    format!("{}::{}", ty_path, ident),
-                                    Applicability::MachineApplicable,
-                                )
-                                .emit();
+                                ));
+                                err.code(error_code!(E0170));
+                                // If this is an irrefutable pattern, and there's > 1 variant,
+                                // then we can't actually match on this. Applying the below
+                                // suggestion would produce code that breaks on `check_irrefutable`.
+                                if rf == Refutable || variant_count == 1 {
+                                    err.span_suggestion(
+                                        p.span,
+                                        "to match on the variant, qualify the path",
+                                        format!("{}::{}", ty_path, ident),
+                                        Applicability::MachineApplicable,
+                                    );
+                                }
+                                err.emit();
                             },
                         )
                     }
@@ -344,12 +356,11 @@ fn check_for_bindings_named_same_as_variants(cx: &MatchVisitor<'_, '_>, pat: &Pa
 }
 
 /// Checks for common cases of "catchall" patterns that may not be intended as such.
-fn pat_is_catchall(pat: &super::Pat<'_>) -> bool {
-    use PatKind::*;
-    match &*pat.kind {
-        Binding { subpattern: None, .. } => true,
-        Binding { subpattern: Some(s), .. } | Deref { subpattern: s } => pat_is_catchall(s),
-        Leaf { subpatterns: s } => s.iter().all(|p| pat_is_catchall(&p.pattern)),
+fn pat_is_catchall(pat: &DeconstructedPat<'_, '_>) -> bool {
+    use Constructor::*;
+    match pat.ctor() {
+        Wildcard => true,
+        Single => pat.iter_fields().all(|pat| pat_is_catchall(pat)),
         _ => false,
     }
 }
@@ -428,29 +439,16 @@ fn irrefutable_let_pattern(tcx: TyCtxt<'_>, id: HirId, span: Span) {
 fn check_let_reachability<'p, 'tcx>(
     cx: &mut MatchCheckCtxt<'p, 'tcx>,
     pat_id: HirId,
-    pat: &'p super::Pat<'tcx>,
+    pat: &'p DeconstructedPat<'p, 'tcx>,
     span: Span,
 ) {
     let arms = [MatchArm { pat, hir_id: pat_id, has_guard: false }];
-    let report = compute_match_usefulness(&cx, &arms, pat_id, pat.ty);
-
-    report_arm_reachability(&cx, &report, |arm_index, arm_span, arm_hir_id, _| {
-        match let_source(cx.tcx, pat_id) {
-            LetSource::IfLet | LetSource::WhileLet => {
-                match arm_index {
-                    // The arm with the user-specified pattern.
-                    0 => unreachable_pattern(cx.tcx, arm_span, arm_hir_id, None),
-                    // The arm with the wildcard pattern.
-                    1 => irrefutable_let_pattern(cx.tcx, pat_id, arm_span),
-                    _ => bug!(),
-                }
-            }
-            LetSource::IfLetGuard if arm_index == 0 => {
-                unreachable_pattern(cx.tcx, arm_span, arm_hir_id, None);
-            }
-            _ => {}
-        }
-    });
+    let report = compute_match_usefulness(&cx, &arms, pat_id, pat.ty());
+
+    // Report if the pattern is unreachable, which can only occur when the type is uninhabited.
+    // This also reports unreachable sub-patterns though, so we can't just replace it with an
+    // `is_uninhabited` check.
+    report_arm_reachability(&cx, &report);
 
     if report.non_exhaustiveness_witnesses.is_empty() {
         // The match is exhaustive, i.e. the `if let` pattern is irrefutable.
@@ -459,18 +457,15 @@ fn check_let_reachability<'p, 'tcx>(
 }
 
 /// Report unreachable arms, if any.
-fn report_arm_reachability<'p, 'tcx, F>(
+fn report_arm_reachability<'p, 'tcx>(
     cx: &MatchCheckCtxt<'p, 'tcx>,
     report: &UsefulnessReport<'p, 'tcx>,
-    unreachable: F,
-) where
-    F: Fn(usize, Span, HirId, Option<Span>),
-{
+) {
     use Reachability::*;
     let mut catchall = None;
-    for (arm_index, (arm, is_useful)) in report.arm_usefulness.iter().enumerate() {
+    for (arm, is_useful) in report.arm_usefulness.iter() {
         match is_useful {
-            Unreachable => unreachable(arm_index, arm.pat.span, arm.hir_id, catchall),
+            Unreachable => unreachable_pattern(cx.tcx, arm.pat.span(), arm.hir_id, catchall),
             Reachable(unreachables) if unreachables.is_empty() => {}
             // The arm is reachable, but contains unreachable subpatterns (from or-patterns).
             Reachable(unreachables) => {
@@ -483,7 +478,7 @@ fn report_arm_reachability<'p, 'tcx, F>(
             }
         }
         if !arm.has_guard && catchall.is_none() && pat_is_catchall(arm.pat) {
-            catchall = Some(arm.pat.span);
+            catchall = Some(arm.pat.span());
         }
     }
 }
@@ -493,7 +488,7 @@ fn non_exhaustive_match<'p, 'tcx>(
     cx: &MatchCheckCtxt<'p, 'tcx>,
     scrut_ty: Ty<'tcx>,
     sp: Span,
-    witnesses: Vec<super::Pat<'tcx>>,
+    witnesses: Vec<DeconstructedPat<'p, 'tcx>>,
     is_empty_match: bool,
 ) {
     let non_empty_enum = match scrut_ty.kind() {
@@ -510,7 +505,7 @@ fn non_exhaustive_match<'p, 'tcx>(
             format!("non-exhaustive patterns: type `{}` is non-empty", scrut_ty),
         );
     } else {
-        let joined_patterns = joined_uncovered_patterns(&witnesses);
+        let joined_patterns = joined_uncovered_patterns(cx, &witnesses);
         err = create_e0004(
             cx.tcx.sess,
             sp,
@@ -537,7 +532,7 @@ fn non_exhaustive_match<'p, 'tcx>(
     if (scrut_ty == cx.tcx.types.usize || scrut_ty == cx.tcx.types.isize)
         && !is_empty_match
         && witnesses.len() == 1
-        && is_wildcard(&witnesses[0])
+        && matches!(witnesses[0].ctor(), Constructor::NonExhaustive)
     {
         err.note(&format!(
             "`{}` does not have a fixed maximum value, \
@@ -560,33 +555,40 @@ fn non_exhaustive_match<'p, 'tcx>(
     err.emit();
 }
 
-crate fn joined_uncovered_patterns(witnesses: &[super::Pat<'_>]) -> String {
+crate fn joined_uncovered_patterns<'p, 'tcx>(
+    cx: &MatchCheckCtxt<'p, 'tcx>,
+    witnesses: &[DeconstructedPat<'p, 'tcx>],
+) -> String {
     const LIMIT: usize = 3;
+    let pat_to_str = |pat: &DeconstructedPat<'p, 'tcx>| pat.to_pat(cx).to_string();
     match witnesses {
         [] => bug!(),
-        [witness] => format!("`{}`", witness),
+        [witness] => format!("`{}`", witness.to_pat(cx)),
         [head @ .., tail] if head.len() < LIMIT => {
-            let head: Vec<_> = head.iter().map(<_>::to_string).collect();
-            format!("`{}` and `{}`", head.join("`, `"), tail)
+            let head: Vec<_> = head.iter().map(pat_to_str).collect();
+            format!("`{}` and `{}`", head.join("`, `"), tail.to_pat(cx))
         }
         _ => {
             let (head, tail) = witnesses.split_at(LIMIT);
-            let head: Vec<_> = head.iter().map(<_>::to_string).collect();
+            let head: Vec<_> = head.iter().map(pat_to_str).collect();
             format!("`{}` and {} more", head.join("`, `"), tail.len())
         }
     }
 }
 
-crate fn pattern_not_covered_label(witnesses: &[super::Pat<'_>], joined_patterns: &str) -> String {
+crate fn pattern_not_covered_label(
+    witnesses: &[DeconstructedPat<'_, '_>],
+    joined_patterns: &str,
+) -> String {
     format!("pattern{} {} not covered", rustc_errors::pluralize!(witnesses.len()), joined_patterns)
 }
 
 /// Point at the definition of non-covered `enum` variants.
-fn adt_defined_here(
-    cx: &MatchCheckCtxt<'_, '_>,
+fn adt_defined_here<'p, 'tcx>(
+    cx: &MatchCheckCtxt<'p, 'tcx>,
     err: &mut DiagnosticBuilder<'_>,
-    ty: Ty<'_>,
-    witnesses: &[super::Pat<'_>],
+    ty: Ty<'tcx>,
+    witnesses: &[DeconstructedPat<'p, 'tcx>],
 ) {
     let ty = ty.peel_refs();
     if let ty::Adt(def, _) = ty.kind() {
@@ -595,57 +597,42 @@ fn adt_defined_here(
         }
 
         if witnesses.len() < 4 {
-            for sp in maybe_point_at_variant(ty, &witnesses) {
+            for sp in maybe_point_at_variant(cx, def, witnesses.iter()) {
                 err.span_label(sp, "not covered");
             }
         }
     }
 }
 
-fn maybe_point_at_variant(ty: Ty<'_>, patterns: &[super::Pat<'_>]) -> Vec<Span> {
+fn maybe_point_at_variant<'a, 'p: 'a, 'tcx: 'a>(
+    cx: &MatchCheckCtxt<'p, 'tcx>,
+    def: &AdtDef,
+    patterns: impl Iterator<Item = &'a DeconstructedPat<'p, 'tcx>>,
+) -> Vec<Span> {
+    use Constructor::*;
     let mut covered = vec![];
-    if let ty::Adt(def, _) = ty.kind() {
-        // Don't point at variants that have already been covered due to other patterns to avoid
-        // visual clutter.
-        for pattern in patterns {
-            use PatKind::{AscribeUserType, Deref, Leaf, Or, Variant};
-            match &*pattern.kind {
-                AscribeUserType { subpattern, .. } | Deref { subpattern } => {
-                    covered.extend(maybe_point_at_variant(ty, slice::from_ref(&subpattern)));
+    for pattern in patterns {
+        if let Variant(variant_index) = pattern.ctor() {
+            if let ty::Adt(this_def, _) = pattern.ty().kind() {
+                if this_def.did != def.did {
+                    continue;
                 }
-                Variant { adt_def, variant_index, subpatterns, .. } if adt_def.did == def.did => {
-                    let sp = def.variants[*variant_index].ident.span;
-                    if covered.contains(&sp) {
-                        continue;
-                    }
-                    covered.push(sp);
-
-                    let pats = subpatterns
-                        .iter()
-                        .map(|field_pattern| field_pattern.pattern.clone())
-                        .collect::<Box<[_]>>();
-                    covered.extend(maybe_point_at_variant(ty, &pats));
-                }
-                Leaf { subpatterns } => {
-                    let pats = subpatterns
-                        .iter()
-                        .map(|field_pattern| field_pattern.pattern.clone())
-                        .collect::<Box<[_]>>();
-                    covered.extend(maybe_point_at_variant(ty, &pats));
-                }
-                Or { pats } => {
-                    let pats = pats.iter().cloned().collect::<Box<[_]>>();
-                    covered.extend(maybe_point_at_variant(ty, &pats));
-                }
-                _ => {}
             }
+            let sp = def.variants[*variant_index].ident.span;
+            if covered.contains(&sp) {
+                // Don't point at variants that have already been covered due to other patterns to avoid
+                // visual clutter.
+                continue;
+            }
+            covered.push(sp);
         }
+        covered.extend(maybe_point_at_variant(cx, def, pattern.iter_fields()));
     }
     covered
 }
 
 /// Check if a by-value binding is by-value. That is, check if the binding's type is not `Copy`.
-fn is_binding_by_move(cx: &MatchVisitor<'_, '_>, hir_id: HirId, span: Span) -> bool {
+fn is_binding_by_move(cx: &MatchVisitor<'_, '_, '_>, hir_id: HirId, span: Span) -> bool {
     !cx.typeck_results.node_type(hir_id).is_copy_modulo_regions(cx.tcx.at(span), cx.param_env)
 }
 
@@ -659,7 +646,7 @@ fn is_binding_by_move(cx: &MatchVisitor<'_, '_>, hir_id: HirId, span: Span) -> b
 /// - `x @ Some(ref mut? y)`.
 ///
 /// This analysis is *not* subsumed by NLL.
-fn check_borrow_conflicts_in_at_patterns(cx: &MatchVisitor<'_, '_>, pat: &Pat<'_>) {
+fn check_borrow_conflicts_in_at_patterns(cx: &MatchVisitor<'_, '_, '_>, pat: &Pat<'_>) {
     // Extract `sub` in `binding @ sub`.
     let (name, sub) = match &pat.kind {
         hir::PatKind::Binding(.., name, Some(sub)) => (*name, sub),
diff --git a/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs b/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs
index cee2a4db0a8..69a7d44ff39 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs
@@ -46,7 +46,7 @@ use self::Constructor::*;
 use self::SliceKind::*;
 
 use super::compare_const_vals;
-use super::usefulness::{is_wildcard, MatchCheckCtxt, PatCtxt};
+use super::usefulness::{MatchCheckCtxt, PatCtxt};
 
 use rustc_data_structures::captures::Captures;
 use rustc_index::vec::Idx;
@@ -56,16 +56,35 @@ use rustc_middle::mir::interpret::ConstValue;
 use rustc_middle::mir::Field;
 use rustc_middle::thir::{FieldPat, Pat, PatKind, PatRange};
 use rustc_middle::ty::layout::IntegerExt;
-use rustc_middle::ty::{self, Const, Ty, TyCtxt};
+use rustc_middle::ty::{self, Const, Ty, TyCtxt, VariantDef};
 use rustc_session::lint;
 use rustc_span::{Span, DUMMY_SP};
 use rustc_target::abi::{Integer, Size, VariantIdx};
 
 use smallvec::{smallvec, SmallVec};
+use std::cell::Cell;
 use std::cmp::{self, max, min, Ordering};
+use std::fmt;
 use std::iter::{once, IntoIterator};
 use std::ops::RangeInclusive;
 
+/// Recursively expand this pattern into its subpatterns. Only useful for or-patterns.
+fn expand_or_pat<'p, 'tcx>(pat: &'p Pat<'tcx>) -> Vec<&'p Pat<'tcx>> {
+    fn expand<'p, 'tcx>(pat: &'p Pat<'tcx>, vec: &mut Vec<&'p Pat<'tcx>>) {
+        if let PatKind::Or { pats } = pat.kind.as_ref() {
+            for pat in pats {
+                expand(pat, vec);
+            }
+        } else {
+            vec.push(pat)
+        }
+    }
+
+    let mut pats = Vec::new();
+    expand(pat, &mut pats);
+    pats
+}
+
 /// An inclusive interval, used for precise integer exhaustiveness checking.
 /// `IntRange`s always store a contiguous range. This means that values are
 /// encoded such that `0` encodes the minimum value for the integer,
@@ -76,9 +95,13 @@ use std::ops::RangeInclusive;
 ///
 /// `IntRange` is never used to encode an empty range or a "range" that wraps
 /// around the (offset) space: i.e., `range.lo <= range.hi`.
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, PartialEq, Eq)]
 pub(super) struct IntRange {
     range: RangeInclusive<u128>,
+    /// Keeps the bias used for encoding the range. It depends on the type of the range and
+    /// possibly the pointer size of the current architecture. The algorithm ensures we never
+    /// compare `IntRange`s with different types/architectures.
+    bias: u128,
 }
 
 impl IntRange {
@@ -131,7 +154,7 @@ impl IntRange {
                 value.try_eval_bits(tcx, param_env, ty)
             })()?;
             let val = val ^ bias;
-            Some(IntRange { range: val..=val })
+            Some(IntRange { range: val..=val, bias })
         } else {
             None
         }
@@ -155,7 +178,7 @@ impl IntRange {
                 // This should have been caught earlier by E0030.
                 bug!("malformed range pattern: {}..={}", lo, (hi - offset));
             }
-            Some(IntRange { range: lo..=(hi - offset) })
+            Some(IntRange { range: lo..=(hi - offset), bias })
         } else {
             None
         }
@@ -180,7 +203,7 @@ impl IntRange {
         let (lo, hi) = self.boundaries();
         let (other_lo, other_hi) = other.boundaries();
         if lo <= other_hi && other_lo <= hi {
-            Some(IntRange { range: max(lo, other_lo)..=min(hi, other_hi) })
+            Some(IntRange { range: max(lo, other_lo)..=min(hi, other_hi), bias: self.bias })
         } else {
             None
         }
@@ -203,10 +226,11 @@ impl IntRange {
         (lo == other_hi || hi == other_lo) && !self.is_singleton() && !other.is_singleton()
     }
 
+    /// Only used for displaying the range properly.
     fn to_pat<'tcx>(&self, tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Pat<'tcx> {
         let (lo, hi) = self.boundaries();
 
-        let bias = IntRange::signed_bias(tcx, ty);
+        let bias = self.bias;
         let (lo, hi) = (lo ^ bias, hi ^ bias);
 
         let env = ty::ParamEnv::empty().and(ty);
@@ -223,10 +247,10 @@ impl IntRange {
     }
 
     /// Lint on likely incorrect range patterns (#63987)
-    pub(super) fn lint_overlapping_range_endpoints<'a, 'tcx: 'a>(
+    pub(super) fn lint_overlapping_range_endpoints<'a, 'p: 'a, 'tcx: 'a>(
         &self,
-        pcx: PatCtxt<'_, '_, 'tcx>,
-        ctors: impl Iterator<Item = (&'a Constructor<'tcx>, Span)>,
+        pcx: PatCtxt<'_, 'p, 'tcx>,
+        pats: impl Iterator<Item = &'a DeconstructedPat<'p, 'tcx>>,
         column_count: usize,
         hir_id: HirId,
     ) {
@@ -248,8 +272,8 @@ impl IntRange {
             return;
         }
 
-        let overlaps: Vec<_> = ctors
-            .filter_map(|(ctor, span)| Some((ctor.as_int_range()?, span)))
+        let overlaps: Vec<_> = pats
+            .filter_map(|pat| Some((pat.ctor().as_int_range()?, pat.span())))
             .filter(|(range, _)| self.suspicious_intersection(range))
             .map(|(range, span)| (self.intersection(&range).unwrap(), span))
             .collect();
@@ -291,6 +315,19 @@ impl IntRange {
     }
 }
 
+/// Note: this is often not what we want: e.g. `false` is converted into the range `0..=0` and
+/// would be displayed as such. To render properly, convert to a pattern first.
+impl fmt::Debug for IntRange {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let (lo, hi) = self.boundaries();
+        let bias = self.bias;
+        let (lo, hi) = (lo ^ bias, hi ^ bias);
+        write!(f, "{}", lo)?;
+        write!(f, "{}", RangeEnd::Included)?;
+        write!(f, "{}", hi)
+    }
+}
+
 /// Represents a border between 2 integers. Because the intervals spanning borders must be able to
 /// cover every integer, we need to be able to represent 2^128 + 1 such borders.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
@@ -375,13 +412,13 @@ impl SplitIntRange {
             // Skip duplicates.
             .filter(|(prev_border, border)| prev_border != border)
             // Finally, convert to ranges.
-            .map(|(prev_border, border)| {
+            .map(move |(prev_border, border)| {
                 let range = match (prev_border, border) {
                     (JustBefore(n), JustBefore(m)) if n < m => n..=(m - 1),
                     (JustBefore(n), AfterMax) => n..=u128::MAX,
                     _ => unreachable!(), // Ruled out by the sorting and filtering we did
                 };
-                IntRange { range }
+                IntRange { range, bias: self.range.bias }
             })
     }
 }
@@ -389,17 +426,17 @@ impl SplitIntRange {
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 enum SliceKind {
     /// Patterns of length `n` (`[x, y]`).
-    FixedLen(u64),
+    FixedLen(usize),
     /// Patterns using the `..` notation (`[x, .., y]`).
     /// Captures any array constructor of `length >= i + j`.
     /// In the case where `array_len` is `Some(_)`,
     /// this indicates that we only care about the first `i` and the last `j` values of the array,
     /// and everything in between is a wildcard `_`.
-    VarLen(u64, u64),
+    VarLen(usize, usize),
 }
 
 impl SliceKind {
-    fn arity(self) -> u64 {
+    fn arity(self) -> usize {
         match self {
             FixedLen(length) => length,
             VarLen(prefix, suffix) => prefix + suffix,
@@ -407,7 +444,7 @@ impl SliceKind {
     }
 
     /// Whether this pattern includes patterns of length `other_len`.
-    fn covers_length(self, other_len: u64) -> bool {
+    fn covers_length(self, other_len: usize) -> bool {
         match self {
             FixedLen(len) => len == other_len,
             VarLen(prefix, suffix) => prefix + suffix <= other_len,
@@ -419,13 +456,13 @@ impl SliceKind {
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub(super) struct Slice {
     /// `None` if the matched value is a slice, `Some(n)` if it is an array of size `n`.
-    array_len: Option<u64>,
+    array_len: Option<usize>,
     /// The kind of pattern it is: fixed-length `[x, y]` or variable length `[x, .., y]`.
     kind: SliceKind,
 }
 
 impl Slice {
-    fn new(array_len: Option<u64>, kind: SliceKind) -> Self {
+    fn new(array_len: Option<usize>, kind: SliceKind) -> Self {
         let kind = match (array_len, kind) {
             // If the middle `..` is empty, we effectively have a fixed-length pattern.
             (Some(len), VarLen(prefix, suffix)) if prefix + suffix >= len => FixedLen(len),
@@ -434,7 +471,7 @@ impl Slice {
         Slice { array_len, kind }
     }
 
-    fn arity(self) -> u64 {
+    fn arity(self) -> usize {
         self.kind.arity()
     }
 
@@ -508,16 +545,16 @@ impl Slice {
 #[derive(Debug)]
 struct SplitVarLenSlice {
     /// If the type is an array, this is its size.
-    array_len: Option<u64>,
+    array_len: Option<usize>,
     /// The arity of the input slice.
-    arity: u64,
+    arity: usize,
     /// The smallest slice bigger than any slice seen. `max_slice.arity()` is the length `L`
     /// described above.
     max_slice: SliceKind,
 }
 
 impl SplitVarLenSlice {
-    fn new(prefix: u64, suffix: u64, array_len: Option<u64>) -> Self {
+    fn new(prefix: usize, suffix: usize, array_len: Option<usize>) -> Self {
         SplitVarLenSlice { array_len, arity: prefix + suffix, max_slice: VarLen(prefix, suffix) }
     }
 
@@ -611,6 +648,8 @@ pub(super) enum Constructor<'tcx> {
     Missing { nonexhaustive_enum_missing_real_variants: bool },
     /// Wildcard pattern.
     Wildcard,
+    /// Or-pattern.
+    Or,
 }
 
 impl<'tcx> Constructor<'tcx> {
@@ -647,60 +686,34 @@ impl<'tcx> Constructor<'tcx> {
         }
     }
 
-    /// Determines the constructor that the given pattern can be specialized to.
-    pub(super) fn from_pat<'p>(cx: &MatchCheckCtxt<'p, 'tcx>, pat: &'p Pat<'tcx>) -> Self {
-        match pat.kind.as_ref() {
-            PatKind::AscribeUserType { .. } => bug!(), // Handled by `expand_pattern`
-            PatKind::Binding { .. } | PatKind::Wild => Wildcard,
-            PatKind::Leaf { .. } | PatKind::Deref { .. } => Single,
-            &PatKind::Variant { variant_index, .. } => Variant(variant_index),
-            PatKind::Constant { value } => {
-                if let Some(int_range) = IntRange::from_const(cx.tcx, cx.param_env, value) {
-                    IntRange(int_range)
-                } else {
-                    match pat.ty.kind() {
-                        ty::Float(_) => FloatRange(value, value, RangeEnd::Included),
-                        // In `expand_pattern`, we convert string literals to `&CONST` patterns with
-                        // `CONST` a pattern of type `str`. In truth this contains a constant of type
-                        // `&str`.
-                        ty::Str => Str(value),
-                        // All constants that can be structurally matched have already been expanded
-                        // into the corresponding `Pat`s by `const_to_pat`. Constants that remain are
-                        // opaque.
-                        _ => Opaque,
+    /// The number of fields for this constructor. This must be kept in sync with
+    /// `Fields::wildcards`.
+    pub(super) fn arity(&self, pcx: PatCtxt<'_, '_, 'tcx>) -> usize {
+        match self {
+            Single | Variant(_) => match pcx.ty.kind() {
+                ty::Tuple(fs) => fs.len(),
+                ty::Ref(..) => 1,
+                ty::Adt(adt, ..) => {
+                    if adt.is_box() {
+                        // The only legal patterns of type `Box` (outside `std`) are `_` and box
+                        // patterns. If we're here we can assume this is a box pattern.
+                        1
+                    } else {
+                        let variant = &adt.variants[self.variant_index_for_adt(adt)];
+                        Fields::list_variant_nonhidden_fields(pcx.cx, pcx.ty, variant).count()
                     }
                 }
-            }
-            &PatKind::Range(PatRange { lo, hi, end }) => {
-                let ty = lo.ty;
-                if let Some(int_range) = IntRange::from_range(
-                    cx.tcx,
-                    lo.eval_bits(cx.tcx, cx.param_env, lo.ty),
-                    hi.eval_bits(cx.tcx, cx.param_env, hi.ty),
-                    ty,
-                    &end,
-                ) {
-                    IntRange(int_range)
-                } else {
-                    FloatRange(lo, hi, end)
-                }
-            }
-            PatKind::Array { prefix, slice, suffix } | PatKind::Slice { prefix, slice, suffix } => {
-                let array_len = match pat.ty.kind() {
-                    ty::Array(_, length) => Some(length.eval_usize(cx.tcx, cx.param_env)),
-                    ty::Slice(_) => None,
-                    _ => span_bug!(pat.span, "bad ty {:?} for slice pattern", pat.ty),
-                };
-                let prefix = prefix.len() as u64;
-                let suffix = suffix.len() as u64;
-                let kind = if slice.is_some() {
-                    VarLen(prefix, suffix)
-                } else {
-                    FixedLen(prefix + suffix)
-                };
-                Slice(Slice::new(array_len, kind))
-            }
-            PatKind::Or { .. } => bug!("Or-pattern should have been expanded earlier on."),
+                _ => bug!("Unexpected type for `Single` constructor: {:?}", pcx.ty),
+            },
+            Slice(slice) => slice.arity(),
+            Str(..)
+            | FloatRange(..)
+            | IntRange(..)
+            | NonExhaustive
+            | Opaque
+            | Missing { .. }
+            | Wildcard => 0,
+            Or => bug!("The `Or` constructor doesn't have a fixed arity"),
         }
     }
 
@@ -823,7 +836,7 @@ impl<'tcx> Constructor<'tcx> {
         match self {
             // If `self` is `Single`, `used_ctors` cannot contain anything else than `Single`s.
             Single => !used_ctors.is_empty(),
-            Variant(_) => used_ctors.iter().any(|c| c == self),
+            Variant(vid) => used_ctors.iter().any(|c| matches!(c, Variant(i) if i == vid)),
             IntRange(range) => used_ctors
                 .iter()
                 .filter_map(|c| c.as_int_range())
@@ -834,7 +847,7 @@ impl<'tcx> Constructor<'tcx> {
                 .any(|other| slice.is_covered_by(other)),
             // This constructor is never covered by anything else
             NonExhaustive => false,
-            Str(..) | FloatRange(..) | Opaque | Missing { .. } | Wildcard => {
+            Str(..) | FloatRange(..) | Opaque | Missing { .. } | Wildcard | Or => {
                 span_bug!(pcx.span, "found unexpected ctor in all_ctors: {:?}", self)
             }
         }
@@ -885,7 +898,7 @@ impl<'tcx> SplitWildcard<'tcx> {
         let all_ctors = match pcx.ty.kind() {
             ty::Bool => smallvec![make_range(0, 1)],
             ty::Array(sub_ty, len) if len.try_eval_usize(cx.tcx, cx.param_env).is_some() => {
-                let len = len.eval_usize(cx.tcx, cx.param_env);
+                let len = len.eval_usize(cx.tcx, cx.param_env) as usize;
                 if len != 0 && cx.is_uninhabited(sub_ty) {
                     smallvec![]
                 } else {
@@ -1073,120 +1086,106 @@ impl<'tcx> SplitWildcard<'tcx> {
     }
 }
 
-/// Some fields need to be explicitly hidden away in certain cases; see the comment above the
-/// `Fields` struct. This struct represents such a potentially-hidden field.
-#[derive(Debug, Copy, Clone)]
-pub(super) enum FilteredField<'p, 'tcx> {
-    Kept(&'p Pat<'tcx>),
-    Hidden,
-}
-
-impl<'p, 'tcx> FilteredField<'p, 'tcx> {
-    fn kept(self) -> Option<&'p Pat<'tcx>> {
-        match self {
-            FilteredField::Kept(p) => Some(p),
-            FilteredField::Hidden => None,
-        }
-    }
-}
-
 /// A value can be decomposed into a constructor applied to some fields. This struct represents
 /// those fields, generalized to allow patterns in each field. See also `Constructor`.
-/// This is constructed from a constructor using [`Fields::wildcards()`].
 ///
-/// If a private or `non_exhaustive` field is uninhabited, the code mustn't observe that it is
-/// uninhabited. For that, we filter these fields out of the matrix. This is handled automatically
-/// in `Fields`. This filtering is uncommon in practice, because uninhabited fields are rarely used,
-/// so we avoid it when possible to preserve performance.
-#[derive(Debug, Clone)]
-pub(super) enum Fields<'p, 'tcx> {
-    /// Lists of patterns that don't contain any filtered fields.
-    /// `Slice` and `Vec` behave the same; the difference is only to avoid allocating and
-    /// triple-dereferences when possible. Frankly this is premature optimization, I (Nadrieril)
-    /// have not measured if it really made a difference.
-    Slice(&'p [Pat<'tcx>]),
-    Vec(SmallVec<[&'p Pat<'tcx>; 2]>),
-    /// Patterns where some of the fields need to be hidden. For all intents and purposes we only
-    /// care about the non-hidden fields. We need to keep the real field index for those fields;
-    /// we're morally storing a `Vec<(usize, &Pat)>` but what we do is more convenient.
-    /// `len` counts the number of non-hidden fields
-    Filtered {
-        fields: SmallVec<[FilteredField<'p, 'tcx>; 2]>,
-        len: usize,
-    },
+/// This is constructed for a constructor using [`Fields::wildcards()`]. The idea is that
+/// [`Fields::wildcards()`] constructs a list of fields where all entries are wildcards, and then
+/// given a pattern we fill some of the fields with its subpatterns.
+/// In the following example `Fields::wildcards` returns `[_, _, _, _]`. Then in
+/// `extract_pattern_arguments` we fill some of the entries, and the result is
+/// `[Some(0), _, _, _]`.
+/// ```rust
+/// let x: [Option<u8>; 4] = foo();
+/// match x {
+///     [Some(0), ..] => {}
+/// }
+/// ```
+///
+/// Note that the number of fields of a constructor may not match the fields declared in the
+/// original struct/variant. This happens if a private or `non_exhaustive` field is uninhabited,
+/// because the code mustn't observe that it is uninhabited. In that case that field is not
+/// included in `fields`. For that reason, when you have a `mir::Field` you must use
+/// `index_with_declared_idx`.
+#[derive(Debug, Clone, Copy)]
+pub(super) struct Fields<'p, 'tcx> {
+    fields: &'p [DeconstructedPat<'p, 'tcx>],
 }
 
 impl<'p, 'tcx> Fields<'p, 'tcx> {
-    /// Internal use. Use `Fields::wildcards()` instead.
-    /// Must not be used if the pattern is a field of a struct/tuple/variant.
-    fn from_single_pattern(pat: &'p Pat<'tcx>) -> Self {
-        Fields::Slice(std::slice::from_ref(pat))
+    fn empty() -> Self {
+        Fields { fields: &[] }
+    }
+
+    fn singleton(cx: &MatchCheckCtxt<'p, 'tcx>, field: DeconstructedPat<'p, 'tcx>) -> Self {
+        let field: &_ = cx.pattern_arena.alloc(field);
+        Fields { fields: std::slice::from_ref(field) }
+    }
+
+    pub(super) fn from_iter(
+        cx: &MatchCheckCtxt<'p, 'tcx>,
+        fields: impl IntoIterator<Item = DeconstructedPat<'p, 'tcx>>,
+    ) -> Self {
+        let fields: &[_] = cx.pattern_arena.alloc_from_iter(fields);
+        Fields { fields }
     }
 
-    /// Convenience; internal use.
     fn wildcards_from_tys(
         cx: &MatchCheckCtxt<'p, 'tcx>,
         tys: impl IntoIterator<Item = Ty<'tcx>>,
     ) -> Self {
-        let wilds = tys.into_iter().map(Pat::wildcard_from_ty);
-        let pats = cx.pattern_arena.alloc_from_iter(wilds);
-        Fields::Slice(pats)
+        Fields::from_iter(cx, tys.into_iter().map(DeconstructedPat::wildcard))
     }
 
-    /// Creates a new list of wildcard fields for a given constructor.
-    pub(super) fn wildcards(pcx: PatCtxt<'_, 'p, 'tcx>, constructor: &Constructor<'tcx>) -> Self {
-        let ty = pcx.ty;
-        let cx = pcx.cx;
-        let wildcard_from_ty = |ty| &*cx.pattern_arena.alloc(Pat::wildcard_from_ty(ty));
+    // In the cases of either a `#[non_exhaustive]` field list or a non-public field, we hide
+    // uninhabited fields in order not to reveal the uninhabitedness of the whole variant.
+    // This lists the fields we keep along with their types.
+    fn list_variant_nonhidden_fields<'a>(
+        cx: &'a MatchCheckCtxt<'p, 'tcx>,
+        ty: Ty<'tcx>,
+        variant: &'a VariantDef,
+    ) -> impl Iterator<Item = (Field, Ty<'tcx>)> + Captures<'a> + Captures<'p> {
+        let (adt, substs) = match ty.kind() {
+            ty::Adt(adt, substs) => (adt, substs),
+            _ => bug!(),
+        };
+        // Whether we must not match the fields of this variant exhaustively.
+        let is_non_exhaustive = variant.is_field_list_non_exhaustive() && !adt.did.is_local();
+
+        variant.fields.iter().enumerate().filter_map(move |(i, field)| {
+            let ty = field.ty(cx.tcx, substs);
+            let is_visible = adt.is_enum() || field.vis.is_accessible_from(cx.module, cx.tcx);
+            let is_uninhabited = cx.is_uninhabited(ty);
+
+            if is_uninhabited && (!is_visible || is_non_exhaustive) {
+                None
+            } else {
+                Some((Field::new(i), ty))
+            }
+        })
+    }
 
+    /// Creates a new list of wildcard fields for a given constructor. The result must have a
+    /// length of `constructor.arity()`.
+    pub(super) fn wildcards(
+        cx: &MatchCheckCtxt<'p, 'tcx>,
+        ty: Ty<'tcx>,
+        constructor: &Constructor<'tcx>,
+    ) -> Self {
         let ret = match constructor {
             Single | Variant(_) => match ty.kind() {
-                ty::Tuple(ref fs) => {
-                    Fields::wildcards_from_tys(cx, fs.into_iter().map(|ty| ty.expect_ty()))
-                }
-                ty::Ref(_, rty, _) => Fields::from_single_pattern(wildcard_from_ty(rty)),
+                ty::Tuple(fs) => Fields::wildcards_from_tys(cx, fs.iter().map(|ty| ty.expect_ty())),
+                ty::Ref(_, rty, _) => Fields::wildcards_from_tys(cx, once(*rty)),
                 ty::Adt(adt, substs) => {
                     if adt.is_box() {
-                        // Use T as the sub pattern type of Box<T>.
-                        Fields::from_single_pattern(wildcard_from_ty(substs.type_at(0)))
+                        // The only legal patterns of type `Box` (outside `std`) are `_` and box
+                        // patterns. If we're here we can assume this is a box pattern.
+                        Fields::wildcards_from_tys(cx, once(substs.type_at(0)))
                     } else {
                         let variant = &adt.variants[constructor.variant_index_for_adt(adt)];
-                        // Whether we must not match the fields of this variant exhaustively.
-                        let is_non_exhaustive =
-                            variant.is_field_list_non_exhaustive() && !adt.did.is_local();
-                        let field_tys = variant.fields.iter().map(|field| field.ty(cx.tcx, substs));
-                        // In the following cases, we don't need to filter out any fields. This is
-                        // the vast majority of real cases, since uninhabited fields are uncommon.
-                        let has_no_hidden_fields = (adt.is_enum() && !is_non_exhaustive)
-                            || !field_tys.clone().any(|ty| cx.is_uninhabited(ty));
-
-                        if has_no_hidden_fields {
-                            Fields::wildcards_from_tys(cx, field_tys)
-                        } else {
-                            let mut len = 0;
-                            let fields = variant
-                                .fields
-                                .iter()
-                                .map(|field| {
-                                    let ty = field.ty(cx.tcx, substs);
-                                    let is_visible = adt.is_enum()
-                                        || field.vis.is_accessible_from(cx.module, cx.tcx);
-                                    let is_uninhabited = cx.is_uninhabited(ty);
-
-                                    // In the cases of either a `#[non_exhaustive]` field list
-                                    // or a non-public field, we hide uninhabited fields in
-                                    // order not to reveal the uninhabitedness of the whole
-                                    // variant.
-                                    if is_uninhabited && (!is_visible || is_non_exhaustive) {
-                                        FilteredField::Hidden
-                                    } else {
-                                        len += 1;
-                                        FilteredField::Kept(wildcard_from_ty(ty))
-                                    }
-                                })
-                                .collect();
-                            Fields::Filtered { fields, len }
-                        }
+                        let tys = Fields::list_variant_nonhidden_fields(cx, ty, variant)
+                            .map(|(_, ty)| ty);
+                        Fields::wildcards_from_tys(cx, tys)
                     }
                 }
                 _ => bug!("Unexpected type for `Single` constructor: {:?}", ty),
@@ -1204,54 +1203,243 @@ impl<'p, 'tcx> Fields<'p, 'tcx> {
             | NonExhaustive
             | Opaque
             | Missing { .. }
-            | Wildcard => Fields::Slice(&[]),
+            | Wildcard => Fields::empty(),
+            Or => {
+                bug!("called `Fields::wildcards` on an `Or` ctor")
+            }
         };
         debug!("Fields::wildcards({:?}, {:?}) = {:#?}", constructor, ty, ret);
         ret
     }
 
-    /// Apply a constructor to a list of patterns, yielding a new pattern. `self`
-    /// must have as many elements as this constructor's arity.
-    ///
-    /// This is roughly the inverse of `specialize_constructor`.
-    ///
-    /// Examples:
-    ///
-    /// ```text
-    /// ctor: `Constructor::Single`
-    /// ty: `Foo(u32, u32, u32)`
-    /// self: `[10, 20, _]`
-    /// returns `Foo(10, 20, _)`
-    ///
-    /// ctor: `Constructor::Variant(Option::Some)`
-    /// ty: `Option<bool>`
-    /// self: `[false]`
-    /// returns `Some(false)`
-    /// ```
-    pub(super) fn apply(self, pcx: PatCtxt<'_, 'p, 'tcx>, ctor: &Constructor<'tcx>) -> Pat<'tcx> {
-        let subpatterns_and_indices = self.patterns_and_indices();
-        let mut subpatterns = subpatterns_and_indices.iter().map(|&(_, p)| p).cloned();
-
-        let pat = match ctor {
-            Single | Variant(_) => match pcx.ty.kind() {
-                ty::Adt(..) | ty::Tuple(..) => {
-                    // We want the real indices here.
-                    let subpatterns = subpatterns_and_indices
-                        .iter()
-                        .map(|&(field, p)| FieldPat { field, pattern: p.clone() })
-                        .collect();
+    /// Returns the list of patterns.
+    pub(super) fn iter_patterns<'a>(
+        &'a self,
+    ) -> impl Iterator<Item = &'p DeconstructedPat<'p, 'tcx>> + Captures<'a> {
+        self.fields.iter()
+    }
+}
 
-                    if let ty::Adt(adt, substs) = pcx.ty.kind() {
-                        if adt.is_enum() {
-                            PatKind::Variant {
-                                adt_def: adt,
-                                substs,
-                                variant_index: ctor.variant_index_for_adt(adt),
-                                subpatterns,
-                            }
+/// Values and patterns can be represented as a constructor applied to some fields. This represents
+/// a pattern in this form.
+/// This also keeps track of whether the pattern has been foundreachable during analysis. For this
+/// reason we should be careful not to clone patterns for which we care about that. Use
+/// `clone_and_forget_reachability` is you're sure.
+pub(crate) struct DeconstructedPat<'p, 'tcx> {
+    ctor: Constructor<'tcx>,
+    fields: Fields<'p, 'tcx>,
+    ty: Ty<'tcx>,
+    span: Span,
+    reachable: Cell<bool>,
+}
+
+impl<'p, 'tcx> DeconstructedPat<'p, 'tcx> {
+    pub(super) fn wildcard(ty: Ty<'tcx>) -> Self {
+        Self::new(Wildcard, Fields::empty(), ty, DUMMY_SP)
+    }
+
+    pub(super) fn new(
+        ctor: Constructor<'tcx>,
+        fields: Fields<'p, 'tcx>,
+        ty: Ty<'tcx>,
+        span: Span,
+    ) -> Self {
+        DeconstructedPat { ctor, fields, ty, span, reachable: Cell::new(false) }
+    }
+
+    /// Construct a pattern that matches everything that starts with this constructor.
+    /// For example, if `ctor` is a `Constructor::Variant` for `Option::Some`, we get the pattern
+    /// `Some(_)`.
+    pub(super) fn wild_from_ctor(pcx: PatCtxt<'_, 'p, 'tcx>, ctor: Constructor<'tcx>) -> Self {
+        let fields = Fields::wildcards(pcx.cx, pcx.ty, &ctor);
+        DeconstructedPat::new(ctor, fields, pcx.ty, DUMMY_SP)
+    }
+
+    /// Clone this value. This method emphasizes that cloning loses reachability information and
+    /// should be done carefully.
+    pub(super) fn clone_and_forget_reachability(&self) -> Self {
+        DeconstructedPat::new(self.ctor.clone(), self.fields, self.ty, self.span)
+    }
+
+    pub(crate) fn from_pat(cx: &MatchCheckCtxt<'p, 'tcx>, pat: &Pat<'tcx>) -> Self {
+        let mkpat = |pat| DeconstructedPat::from_pat(cx, pat);
+        let ctor;
+        let fields;
+        match pat.kind.as_ref() {
+            PatKind::AscribeUserType { subpattern, .. } => return mkpat(subpattern),
+            PatKind::Binding { subpattern: Some(subpat), .. } => return mkpat(subpat),
+            PatKind::Binding { subpattern: None, .. } | PatKind::Wild => {
+                ctor = Wildcard;
+                fields = Fields::empty();
+            }
+            PatKind::Deref { subpattern } => {
+                ctor = Single;
+                fields = Fields::singleton(cx, mkpat(subpattern));
+            }
+            PatKind::Leaf { subpatterns } | PatKind::Variant { subpatterns, .. } => {
+                match pat.ty.kind() {
+                    ty::Tuple(fs) => {
+                        ctor = Single;
+                        let mut wilds: SmallVec<[_; 2]> = fs
+                            .iter()
+                            .map(|ty| ty.expect_ty())
+                            .map(DeconstructedPat::wildcard)
+                            .collect();
+                        for pat in subpatterns {
+                            wilds[pat.field.index()] = mkpat(&pat.pattern);
+                        }
+                        fields = Fields::from_iter(cx, wilds);
+                    }
+                    ty::Adt(adt, substs) if adt.is_box() => {
+                        // The only legal patterns of type `Box` (outside `std`) are `_` and box
+                        // patterns. If we're here we can assume this is a box pattern.
+                        // FIXME(Nadrieril): A `Box` can in theory be matched either with `Box(_,
+                        // _)` or a box pattern. As a hack to avoid an ICE with the former, we
+                        // ignore other fields than the first one. This will trigger an error later
+                        // anyway.
+                        // See https://github.com/rust-lang/rust/issues/82772 ,
+                        // explanation: https://github.com/rust-lang/rust/pull/82789#issuecomment-796921977
+                        // The problem is that we can't know from the type whether we'll match
+                        // normally or through box-patterns. We'll have to figure out a proper
+                        // solution when we introduce generalized deref patterns. Also need to
+                        // prevent mixing of those two options.
+                        let pat = subpatterns.into_iter().find(|pat| pat.field.index() == 0);
+                        let pat = if let Some(pat) = pat {
+                            mkpat(&pat.pattern)
                         } else {
-                            PatKind::Leaf { subpatterns }
+                            DeconstructedPat::wildcard(substs.type_at(0))
+                        };
+                        ctor = Single;
+                        fields = Fields::singleton(cx, pat);
+                    }
+                    ty::Adt(adt, _) => {
+                        ctor = match pat.kind.as_ref() {
+                            PatKind::Leaf { .. } => Single,
+                            PatKind::Variant { variant_index, .. } => Variant(*variant_index),
+                            _ => bug!(),
+                        };
+                        let variant = &adt.variants[ctor.variant_index_for_adt(adt)];
+                        // For each field in the variant, we store the relevant index into `self.fields` if any.
+                        let mut field_id_to_id: Vec<Option<usize>> =
+                            (0..variant.fields.len()).map(|_| None).collect();
+                        let tys = Fields::list_variant_nonhidden_fields(cx, pat.ty, variant)
+                            .enumerate()
+                            .map(|(i, (field, ty))| {
+                                field_id_to_id[field.index()] = Some(i);
+                                ty
+                            });
+                        let mut wilds: SmallVec<[_; 2]> =
+                            tys.map(DeconstructedPat::wildcard).collect();
+                        for pat in subpatterns {
+                            if let Some(i) = field_id_to_id[pat.field.index()] {
+                                wilds[i] = mkpat(&pat.pattern);
+                            }
+                        }
+                        fields = Fields::from_iter(cx, wilds);
+                    }
+                    _ => bug!("pattern has unexpected type: pat: {:?}, ty: {:?}", pat, pat.ty),
+                }
+            }
+            PatKind::Constant { value } => {
+                if let Some(int_range) = IntRange::from_const(cx.tcx, cx.param_env, value) {
+                    ctor = IntRange(int_range);
+                    fields = Fields::empty();
+                } else {
+                    match pat.ty.kind() {
+                        ty::Float(_) => {
+                            ctor = FloatRange(value, value, RangeEnd::Included);
+                            fields = Fields::empty();
+                        }
+                        ty::Ref(_, t, _) if t.is_str() => {
+                            // We want a `&str` constant to behave like a `Deref` pattern, to be compatible
+                            // with other `Deref` patterns. This could have been done in `const_to_pat`,
+                            // but that causes issues with the rest of the matching code.
+                            // So here, the constructor for a `"foo"` pattern is `&` (represented by
+                            // `Single`), and has one field. That field has constructor `Str(value)` and no
+                            // fields.
+                            // Note: `t` is `str`, not `&str`.
+                            let subpattern =
+                                DeconstructedPat::new(Str(value), Fields::empty(), t, pat.span);
+                            ctor = Single;
+                            fields = Fields::singleton(cx, subpattern)
+                        }
+                        // All constants that can be structurally matched have already been expanded
+                        // into the corresponding `Pat`s by `const_to_pat`. Constants that remain are
+                        // opaque.
+                        _ => {
+                            ctor = Opaque;
+                            fields = Fields::empty();
                         }
+                    }
+                }
+            }
+            &PatKind::Range(PatRange { lo, hi, end }) => {
+                let ty = lo.ty;
+                ctor = if let Some(int_range) = IntRange::from_range(
+                    cx.tcx,
+                    lo.eval_bits(cx.tcx, cx.param_env, lo.ty),
+                    hi.eval_bits(cx.tcx, cx.param_env, hi.ty),
+                    ty,
+                    &end,
+                ) {
+                    IntRange(int_range)
+                } else {
+                    FloatRange(lo, hi, end)
+                };
+                fields = Fields::empty();
+            }
+            PatKind::Array { prefix, slice, suffix } | PatKind::Slice { prefix, slice, suffix } => {
+                let array_len = match pat.ty.kind() {
+                    ty::Array(_, length) => Some(length.eval_usize(cx.tcx, cx.param_env) as usize),
+                    ty::Slice(_) => None,
+                    _ => span_bug!(pat.span, "bad ty {:?} for slice pattern", pat.ty),
+                };
+                let kind = if slice.is_some() {
+                    VarLen(prefix.len(), suffix.len())
+                } else {
+                    FixedLen(prefix.len() + suffix.len())
+                };
+                ctor = Slice(Slice::new(array_len, kind));
+                fields = Fields::from_iter(cx, prefix.iter().chain(suffix).map(mkpat));
+            }
+            PatKind::Or { .. } => {
+                ctor = Or;
+                let pats = expand_or_pat(pat);
+                fields = Fields::from_iter(cx, pats.into_iter().map(mkpat));
+            }
+        }
+        DeconstructedPat::new(ctor, fields, pat.ty, pat.span)
+    }
+
+    pub(crate) fn to_pat(&self, cx: &MatchCheckCtxt<'p, 'tcx>) -> Pat<'tcx> {
+        let is_wildcard = |pat: &Pat<'_>| {
+            matches!(*pat.kind, PatKind::Binding { subpattern: None, .. } | PatKind::Wild)
+        };
+        let mut subpatterns = self.iter_fields().map(|p| p.to_pat(cx));
+        let pat = match &self.ctor {
+            Single | Variant(_) => match self.ty.kind() {
+                ty::Tuple(..) => PatKind::Leaf {
+                    subpatterns: subpatterns
+                        .enumerate()
+                        .map(|(i, p)| FieldPat { field: Field::new(i), pattern: p })
+                        .collect(),
+                },
+                ty::Adt(adt_def, _) if adt_def.is_box() => {
+                    // Without `box_patterns`, the only legal pattern of type `Box` is `_` (outside
+                    // of `std`). So this branch is only reachable when the feature is enabled and
+                    // the pattern is a box pattern.
+                    PatKind::Deref { subpattern: subpatterns.next().unwrap() }
+                }
+                ty::Adt(adt_def, substs) => {
+                    let variant_index = self.ctor.variant_index_for_adt(adt_def);
+                    let variant = &adt_def.variants[variant_index];
+                    let subpatterns = Fields::list_variant_nonhidden_fields(cx, self.ty, variant)
+                        .zip(subpatterns)
+                        .map(|((field, _ty), pattern)| FieldPat { field, pattern })
+                        .collect();
+
+                    if adt_def.is_enum() {
+                        PatKind::Variant { adt_def, substs, variant_index, subpatterns }
                     } else {
                         PatKind::Leaf { subpatterns }
                     }
@@ -1259,195 +1447,239 @@ impl<'p, 'tcx> Fields<'p, 'tcx> {
                 // Note: given the expansion of `&str` patterns done in `expand_pattern`, we should
                 // be careful to reconstruct the correct constant pattern here. However a string
                 // literal pattern will never be reported as a non-exhaustiveness witness, so we
-                // can ignore this issue.
+                // ignore this issue.
                 ty::Ref(..) => PatKind::Deref { subpattern: subpatterns.next().unwrap() },
-                ty::Slice(_) | ty::Array(..) => bug!("bad slice pattern {:?} {:?}", ctor, pcx.ty),
-                _ => PatKind::Wild,
+                _ => bug!("unexpected ctor for type {:?} {:?}", self.ctor, self.ty),
             },
-            Slice(slice) => match slice.kind {
-                FixedLen(_) => {
-                    PatKind::Slice { prefix: subpatterns.collect(), slice: None, suffix: vec![] }
-                }
-                VarLen(prefix, _) => {
-                    let mut prefix: Vec<_> = subpatterns.by_ref().take(prefix as usize).collect();
-                    if slice.array_len.is_some() {
-                        // Improves diagnostics a bit: if the type is a known-size array, instead
-                        // of reporting `[x, _, .., _, y]`, we prefer to report `[x, .., y]`.
-                        // This is incorrect if the size is not known, since `[_, ..]` captures
-                        // arrays of lengths `>= 1` whereas `[..]` captures any length.
-                        while !prefix.is_empty() && is_wildcard(prefix.last().unwrap()) {
-                            prefix.pop();
+            Slice(slice) => {
+                match slice.kind {
+                    FixedLen(_) => PatKind::Slice {
+                        prefix: subpatterns.collect(),
+                        slice: None,
+                        suffix: vec![],
+                    },
+                    VarLen(prefix, _) => {
+                        let mut subpatterns = subpatterns.peekable();
+                        let mut prefix: Vec<_> = subpatterns.by_ref().take(prefix).collect();
+                        if slice.array_len.is_some() {
+                            // Improves diagnostics a bit: if the type is a known-size array, instead
+                            // of reporting `[x, _, .., _, y]`, we prefer to report `[x, .., y]`.
+                            // This is incorrect if the size is not known, since `[_, ..]` captures
+                            // arrays of lengths `>= 1` whereas `[..]` captures any length.
+                            while !prefix.is_empty() && is_wildcard(prefix.last().unwrap()) {
+                                prefix.pop();
+                            }
+                            while subpatterns.peek().is_some()
+                                && is_wildcard(subpatterns.peek().unwrap())
+                            {
+                                subpatterns.next();
+                            }
                         }
+                        let suffix: Vec<_> = subpatterns.collect();
+                        let wild = Pat::wildcard_from_ty(self.ty);
+                        PatKind::Slice { prefix, slice: Some(wild), suffix }
                     }
-                    let suffix: Vec<_> = if slice.array_len.is_some() {
-                        // Same as above.
-                        subpatterns.skip_while(is_wildcard).collect()
-                    } else {
-                        subpatterns.collect()
-                    };
-                    let wild = Pat::wildcard_from_ty(pcx.ty);
-                    PatKind::Slice { prefix, slice: Some(wild), suffix }
                 }
-            },
+            }
             &Str(value) => PatKind::Constant { value },
             &FloatRange(lo, hi, end) => PatKind::Range(PatRange { lo, hi, end }),
-            IntRange(range) => return range.to_pat(pcx.cx.tcx, pcx.ty),
-            NonExhaustive => PatKind::Wild,
-            Wildcard => return Pat::wildcard_from_ty(pcx.ty),
-            Opaque => bug!("we should not try to apply an opaque constructor"),
+            IntRange(range) => return range.to_pat(cx.tcx, self.ty),
+            Wildcard | NonExhaustive => PatKind::Wild,
             Missing { .. } => bug!(
-                "trying to apply the `Missing` constructor; this should have been done in `apply_constructors`"
+                "trying to convert a `Missing` constructor into a `Pat`; this is probably a bug,
+                `Missing` should have been processed in `apply_constructors`"
             ),
+            Opaque | Or => {
+                bug!("can't convert to pattern: {:?}", self)
+            }
         };
 
-        Pat { ty: pcx.ty, span: DUMMY_SP, kind: Box::new(pat) }
+        Pat { ty: self.ty, span: DUMMY_SP, kind: Box::new(pat) }
     }
 
-    /// Returns the number of patterns. This is the same as the arity of the constructor used to
-    /// construct `self`.
-    pub(super) fn len(&self) -> usize {
-        match self {
-            Fields::Slice(pats) => pats.len(),
-            Fields::Vec(pats) => pats.len(),
-            Fields::Filtered { len, .. } => *len,
-        }
+    pub(super) fn is_or_pat(&self) -> bool {
+        matches!(self.ctor, Or)
     }
 
-    /// Returns the list of patterns along with the corresponding field indices.
-    fn patterns_and_indices(&self) -> SmallVec<[(Field, &'p Pat<'tcx>); 2]> {
-        match self {
-            Fields::Slice(pats) => {
-                pats.iter().enumerate().map(|(i, p)| (Field::new(i), p)).collect()
-            }
-            Fields::Vec(pats) => {
-                pats.iter().copied().enumerate().map(|(i, p)| (Field::new(i), p)).collect()
-            }
-            Fields::Filtered { fields, .. } => {
-                // Indices must be relative to the full list of patterns
-                fields
-                    .iter()
-                    .enumerate()
-                    .filter_map(|(i, p)| Some((Field::new(i), p.kept()?)))
-                    .collect()
-            }
-        }
+    pub(super) fn ctor(&self) -> &Constructor<'tcx> {
+        &self.ctor
     }
-
-    /// Returns the list of patterns.
-    pub(super) fn into_patterns(self) -> SmallVec<[&'p Pat<'tcx>; 2]> {
-        match self {
-            Fields::Slice(pats) => pats.iter().collect(),
-            Fields::Vec(pats) => pats,
-            Fields::Filtered { fields, .. } => fields.iter().filter_map(|p| p.kept()).collect(),
-        }
+    pub(super) fn ty(&self) -> Ty<'tcx> {
+        self.ty
     }
-
-    /// Overrides some of the fields with the provided patterns. Exactly like
-    /// `replace_fields_indexed`, except that it takes `FieldPat`s as input.
-    fn replace_with_fieldpats(
-        &self,
-        new_pats: impl IntoIterator<Item = &'p FieldPat<'tcx>>,
-    ) -> Self {
-        self.replace_fields_indexed(
-            new_pats.into_iter().map(|pat| (pat.field.index(), &pat.pattern)),
-        )
+    pub(super) fn span(&self) -> Span {
+        self.span
     }
 
-    /// Overrides some of the fields with the provided patterns. This is used when a pattern
-    /// defines some fields but not all, for example `Foo { field1: Some(_), .. }`: here we start
-    /// with a `Fields` that is just one wildcard per field of the `Foo` struct, and override the
-    /// entry corresponding to `field1` with the pattern `Some(_)`. This is also used for slice
-    /// patterns for the same reason.
-    fn replace_fields_indexed(
-        &self,
-        new_pats: impl IntoIterator<Item = (usize, &'p Pat<'tcx>)>,
-    ) -> Self {
-        let mut fields = self.clone();
-        if let Fields::Slice(pats) = fields {
-            fields = Fields::Vec(pats.iter().collect());
-        }
+    pub(super) fn iter_fields<'a>(
+        &'a self,
+    ) -> impl Iterator<Item = &'p DeconstructedPat<'p, 'tcx>> + Captures<'a> {
+        self.fields.iter_patterns()
+    }
 
-        match &mut fields {
-            Fields::Vec(pats) => {
-                for (i, pat) in new_pats {
-                    if let Some(p) = pats.get_mut(i) {
-                        *p = pat;
-                    }
-                }
+    /// Specialize this pattern with a constructor.
+    /// `other_ctor` can be different from `self.ctor`, but must be covered by it.
+    pub(super) fn specialize<'a>(
+        &'a self,
+        cx: &MatchCheckCtxt<'p, 'tcx>,
+        other_ctor: &Constructor<'tcx>,
+    ) -> SmallVec<[&'p DeconstructedPat<'p, 'tcx>; 2]> {
+        match (&self.ctor, other_ctor) {
+            (Wildcard, _) => {
+                // We return a wildcard for each field of `other_ctor`.
+                Fields::wildcards(cx, self.ty, other_ctor).iter_patterns().collect()
             }
-            Fields::Filtered { fields, .. } => {
-                for (i, pat) in new_pats {
-                    if let FilteredField::Kept(p) = &mut fields[i] {
-                        *p = pat
+            (Slice(self_slice), Slice(other_slice))
+                if self_slice.arity() != other_slice.arity() =>
+            {
+                // The only tricky case: two slices of different arity. Since `self_slice` covers
+                // `other_slice`, `self_slice` must be `VarLen`, i.e. of the form
+                // `[prefix, .., suffix]`. Moreover `other_slice` is guaranteed to have a larger
+                // arity. So we fill the middle part with enough wildcards to reach the length of
+                // the new, larger slice.
+                match self_slice.kind {
+                    FixedLen(_) => bug!("{:?} doesn't cover {:?}", self_slice, other_slice),
+                    VarLen(prefix, suffix) => {
+                        let inner_ty = match *self.ty.kind() {
+                            ty::Slice(ty) | ty::Array(ty, _) => ty,
+                            _ => bug!("bad slice pattern {:?} {:?}", self.ctor, self.ty),
+                        };
+                        let prefix = &self.fields.fields[..prefix];
+                        let suffix = &self.fields.fields[self_slice.arity() - suffix..];
+                        let wildcard: &_ =
+                            cx.pattern_arena.alloc(DeconstructedPat::wildcard(inner_ty));
+                        let extra_wildcards = other_slice.arity() - self_slice.arity();
+                        let extra_wildcards = (0..extra_wildcards).map(|_| wildcard);
+                        prefix.iter().chain(extra_wildcards).chain(suffix).collect()
                     }
                 }
             }
-            Fields::Slice(_) => unreachable!(),
+            _ => self.fields.iter_patterns().collect(),
         }
-        fields
     }
 
-    /// Replaces contained fields with the given list of patterns. There must be `len()` patterns
-    /// in `pats`.
-    pub(super) fn replace_fields(
-        &self,
-        cx: &MatchCheckCtxt<'p, 'tcx>,
-        pats: impl IntoIterator<Item = Pat<'tcx>>,
-    ) -> Self {
-        let pats: &[_] = cx.pattern_arena.alloc_from_iter(pats);
+    /// We keep track for each pattern if it was ever reachable during the analysis. This is used
+    /// with `unreachable_spans` to report unreachable subpatterns arising from or patterns.
+    pub(super) fn set_reachable(&self) {
+        self.reachable.set(true)
+    }
+    pub(super) fn is_reachable(&self) -> bool {
+        self.reachable.get()
+    }
 
-        match self {
-            Fields::Filtered { fields, len } => {
-                let mut pats = pats.iter();
-                let mut fields = fields.clone();
-                for f in &mut fields {
-                    if let FilteredField::Kept(p) = f {
-                        // We take one input pattern for each `Kept` field, in order.
-                        *p = pats.next().unwrap();
-                    }
-                }
-                Fields::Filtered { fields, len: *len }
+    /// Report the spans of subpatterns that were not reachable, if any.
+    pub(super) fn unreachable_spans(&self) -> Vec<Span> {
+        let mut spans = Vec::new();
+        self.collect_unreachable_spans(&mut spans);
+        spans
+    }
+
+    fn collect_unreachable_spans(&self, spans: &mut Vec<Span>) {
+        // We don't look at subpatterns if we already reported the whole pattern as unreachable.
+        if !self.is_reachable() {
+            spans.push(self.span);
+        } else {
+            for p in self.iter_fields() {
+                p.collect_unreachable_spans(spans);
             }
-            _ => Fields::Slice(pats),
         }
     }
+}
 
-    /// Replaces contained fields with the arguments of the given pattern. Only use on a pattern
-    /// that is compatible with the constructor used to build `self`.
-    /// This is meant to be used on the result of `Fields::wildcards()`. The idea is that
-    /// `wildcards` constructs a list of fields where all entries are wildcards, and the pattern
-    /// provided to this function fills some of the fields with non-wildcards.
-    /// In the following example `Fields::wildcards` would return `[_, _, _, _]`. If we call
-    /// `replace_with_pattern_arguments` on it with the pattern, the result will be `[Some(0), _,
-    /// _, _]`.
-    /// ```rust
-    /// let x: [Option<u8>; 4] = foo();
-    /// match x {
-    ///     [Some(0), ..] => {}
-    /// }
-    /// ```
-    /// This is guaranteed to preserve the number of patterns in `self`.
-    pub(super) fn replace_with_pattern_arguments(&self, pat: &'p Pat<'tcx>) -> Self {
-        match pat.kind.as_ref() {
-            PatKind::Deref { subpattern } => {
-                assert_eq!(self.len(), 1);
-                Fields::from_single_pattern(subpattern)
+/// This is mostly copied from the `Pat` impl. This is best effort and not good enough for a
+/// `Display` impl.
+impl<'p, 'tcx> fmt::Debug for DeconstructedPat<'p, 'tcx> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        // Printing lists is a chore.
+        let mut first = true;
+        let mut start_or_continue = |s| {
+            if first {
+                first = false;
+                ""
+            } else {
+                s
             }
-            PatKind::Leaf { subpatterns } | PatKind::Variant { subpatterns, .. } => {
-                self.replace_with_fieldpats(subpatterns)
+        };
+        let mut start_or_comma = || start_or_continue(", ");
+
+        match &self.ctor {
+            Single | Variant(_) => match self.ty.kind() {
+                ty::Adt(def, _) if def.is_box() => {
+                    // Without `box_patterns`, the only legal pattern of type `Box` is `_` (outside
+                    // of `std`). So this branch is only reachable when the feature is enabled and
+                    // the pattern is a box pattern.
+                    let subpattern = self.iter_fields().next().unwrap();
+                    write!(f, "box {:?}", subpattern)
+                }
+                ty::Adt(..) | ty::Tuple(..) => {
+                    let variant = match self.ty.kind() {
+                        ty::Adt(adt, _) => {
+                            Some(&adt.variants[self.ctor.variant_index_for_adt(adt)])
+                        }
+                        ty::Tuple(_) => None,
+                        _ => unreachable!(),
+                    };
+
+                    if let Some(variant) = variant {
+                        write!(f, "{}", variant.ident)?;
+                    }
+
+                    // Without `cx`, we can't know which field corresponds to which, so we can't
+                    // get the names of the fields. Instead we just display everything as a suple
+                    // struct, which should be good enough.
+                    write!(f, "(")?;
+                    for p in self.iter_fields() {
+                        write!(f, "{}", start_or_comma())?;
+                        write!(f, "{:?}", p)?;
+                    }
+                    write!(f, ")")
+                }
+                // Note: given the expansion of `&str` patterns done in `expand_pattern`, we should
+                // be careful to detect strings here. However a string literal pattern will never
+                // be reported as a non-exhaustiveness witness, so we can ignore this issue.
+                ty::Ref(_, _, mutbl) => {
+                    let subpattern = self.iter_fields().next().unwrap();
+                    write!(f, "&{}{:?}", mutbl.prefix_str(), subpattern)
+                }
+                _ => write!(f, "_"),
+            },
+            Slice(slice) => {
+                let mut subpatterns = self.fields.iter_patterns();
+                write!(f, "[")?;
+                match slice.kind {
+                    FixedLen(_) => {
+                        for p in subpatterns {
+                            write!(f, "{}{:?}", start_or_comma(), p)?;
+                        }
+                    }
+                    VarLen(prefix_len, _) => {
+                        for p in subpatterns.by_ref().take(prefix_len) {
+                            write!(f, "{}{:?}", start_or_comma(), p)?;
+                        }
+                        write!(f, "{}", start_or_comma())?;
+                        write!(f, "..")?;
+                        for p in subpatterns {
+                            write!(f, "{}{:?}", start_or_comma(), p)?;
+                        }
+                    }
+                }
+                write!(f, "]")
+            }
+            &FloatRange(lo, hi, end) => {
+                write!(f, "{}", lo)?;
+                write!(f, "{}", end)?;
+                write!(f, "{}", hi)
             }
-            PatKind::Array { prefix, suffix, .. } | PatKind::Slice { prefix, suffix, .. } => {
-                // Number of subpatterns for the constructor
-                let ctor_arity = self.len();
-
-                // Replace the prefix and the suffix with the given patterns, leaving wildcards in
-                // the middle if there was a subslice pattern `..`.
-                let prefix = prefix.iter().enumerate();
-                let suffix =
-                    suffix.iter().enumerate().map(|(i, p)| (ctor_arity - suffix.len() + i, p));
-                self.replace_fields_indexed(prefix.chain(suffix))
+            IntRange(range) => write!(f, "{:?}", range), // Best-effort, will render e.g. `false` as `0..=0`
+            Wildcard | Missing { .. } | NonExhaustive => write!(f, "_"),
+            Or => {
+                for pat in self.iter_fields() {
+                    write!(f, "{}{:?}", start_or_continue(" | "), pat)?;
+                }
+                Ok(())
             }
-            _ => self.clone(),
+            Str(value) => write!(f, "{}", value),
+            Opaque => write!(f, "<constant pattern>"),
         }
     }
 }
diff --git a/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs b/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs
index f4255713e2a..650a87b2d88 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/usefulness.rs
@@ -284,27 +284,22 @@ use self::ArmType::*;
 use self::Usefulness::*;
 
 use super::check_match::{joined_uncovered_patterns, pattern_not_covered_label};
-use super::deconstruct_pat::{Constructor, Fields, SplitWildcard};
-use super::{PatternFoldable, PatternFolder};
+use super::deconstruct_pat::{Constructor, DeconstructedPat, Fields, SplitWildcard};
 
 use rustc_data_structures::captures::Captures;
-use rustc_data_structures::fx::FxHashMap;
 
-use hir::def_id::DefId;
-use hir::HirId;
 use rustc_arena::TypedArena;
-use rustc_hir as hir;
-use rustc_middle::thir::{Pat, PatKind};
+use rustc_hir::def_id::DefId;
+use rustc_hir::HirId;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_session::lint::builtin::NON_EXHAUSTIVE_OMITTED_PATTERNS;
-use rustc_span::Span;
+use rustc_span::{Span, DUMMY_SP};
 
 use smallvec::{smallvec, SmallVec};
 use std::fmt;
-use std::iter::{FromIterator, IntoIterator};
-use std::lazy::OnceCell;
+use std::iter::once;
 
-crate struct MatchCheckCtxt<'a, 'tcx> {
+crate struct MatchCheckCtxt<'p, 'tcx> {
     crate tcx: TyCtxt<'tcx>,
     /// The module in which the match occurs. This is necessary for
     /// checking inhabited-ness of types because whether a type is (visibly)
@@ -313,7 +308,7 @@ crate struct MatchCheckCtxt<'a, 'tcx> {
     /// outside its module and should not be matchable with an empty match statement.
     crate module: DefId,
     crate param_env: ty::ParamEnv<'tcx>,
-    crate pattern_arena: &'a TypedArena<Pat<'tcx>>,
+    crate pattern_arena: &'p TypedArena<DeconstructedPat<'p, 'tcx>>,
 }
 
 impl<'a, 'tcx> MatchCheckCtxt<'a, 'tcx> {
@@ -356,78 +351,20 @@ impl<'a, 'p, 'tcx> fmt::Debug for PatCtxt<'a, 'p, 'tcx> {
     }
 }
 
-crate fn expand_pattern<'tcx>(pat: Pat<'tcx>) -> Pat<'tcx> {
-    LiteralExpander.fold_pattern(&pat)
-}
-
-struct LiteralExpander;
-
-impl<'tcx> PatternFolder<'tcx> for LiteralExpander {
-    fn fold_pattern(&mut self, pat: &Pat<'tcx>) -> Pat<'tcx> {
-        debug!("fold_pattern {:?} {:?} {:?}", pat, pat.ty.kind(), pat.kind);
-        match (pat.ty.kind(), pat.kind.as_ref()) {
-            (_, PatKind::Binding { subpattern: Some(s), .. }) => s.fold_with(self),
-            (_, PatKind::AscribeUserType { subpattern: s, .. }) => s.fold_with(self),
-            (ty::Ref(_, t, _), PatKind::Constant { .. }) if t.is_str() => {
-                // Treat string literal patterns as deref patterns to a `str` constant, i.e.
-                // `&CONST`. This expands them like other const patterns. This could have been done
-                // in `const_to_pat`, but that causes issues with the rest of the matching code.
-                let mut new_pat = pat.super_fold_with(self);
-                // Make a fake const pattern of type `str` (instead of `&str`). That the carried
-                // constant value still knows it is of type `&str`.
-                new_pat.ty = t;
-                Pat {
-                    kind: Box::new(PatKind::Deref { subpattern: new_pat }),
-                    span: pat.span,
-                    ty: pat.ty,
-                }
-            }
-            _ => pat.super_fold_with(self),
-        }
-    }
-}
-
-pub(super) fn is_wildcard(pat: &Pat<'_>) -> bool {
-    matches!(*pat.kind, PatKind::Binding { subpattern: None, .. } | PatKind::Wild)
-}
-
-fn is_or_pat(pat: &Pat<'_>) -> bool {
-    matches!(*pat.kind, PatKind::Or { .. })
-}
-
-/// Recursively expand this pattern into its subpatterns. Only useful for or-patterns.
-fn expand_or_pat<'p, 'tcx>(pat: &'p Pat<'tcx>) -> Vec<&'p Pat<'tcx>> {
-    fn expand<'p, 'tcx>(pat: &'p Pat<'tcx>, vec: &mut Vec<&'p Pat<'tcx>>) {
-        if let PatKind::Or { pats } = pat.kind.as_ref() {
-            for pat in pats {
-                expand(pat, vec);
-            }
-        } else {
-            vec.push(pat)
-        }
-    }
-
-    let mut pats = Vec::new();
-    expand(pat, &mut pats);
-    pats
-}
-
 /// A row of a matrix. Rows of len 1 are very common, which is why `SmallVec[_; 2]`
 /// works well.
 #[derive(Clone)]
 struct PatStack<'p, 'tcx> {
-    pats: SmallVec<[&'p Pat<'tcx>; 2]>,
-    /// Cache for the constructor of the head
-    head_ctor: OnceCell<Constructor<'tcx>>,
+    pats: SmallVec<[&'p DeconstructedPat<'p, 'tcx>; 2]>,
 }
 
 impl<'p, 'tcx> PatStack<'p, 'tcx> {
-    fn from_pattern(pat: &'p Pat<'tcx>) -> Self {
+    fn from_pattern(pat: &'p DeconstructedPat<'p, 'tcx>) -> Self {
         Self::from_vec(smallvec![pat])
     }
 
-    fn from_vec(vec: SmallVec<[&'p Pat<'tcx>; 2]>) -> Self {
-        PatStack { pats: vec, head_ctor: OnceCell::new() }
+    fn from_vec(vec: SmallVec<[&'p DeconstructedPat<'p, 'tcx>; 2]>) -> Self {
+        PatStack { pats: vec }
     }
 
     fn is_empty(&self) -> bool {
@@ -438,79 +375,56 @@ impl<'p, 'tcx> PatStack<'p, 'tcx> {
         self.pats.len()
     }
 
-    fn head(&self) -> &'p Pat<'tcx> {
+    fn head(&self) -> &'p DeconstructedPat<'p, 'tcx> {
         self.pats[0]
     }
 
-    #[inline]
-    fn head_ctor<'a>(&'a self, cx: &MatchCheckCtxt<'p, 'tcx>) -> &'a Constructor<'tcx> {
-        self.head_ctor.get_or_init(|| Constructor::from_pat(cx, self.head()))
-    }
-
-    fn iter(&self) -> impl Iterator<Item = &Pat<'tcx>> {
+    fn iter(&self) -> impl Iterator<Item = &DeconstructedPat<'p, 'tcx>> {
         self.pats.iter().copied()
     }
 
     // Recursively expand the first pattern into its subpatterns. Only useful if the pattern is an
     // or-pattern. Panics if `self` is empty.
     fn expand_or_pat<'a>(&'a self) -> impl Iterator<Item = PatStack<'p, 'tcx>> + Captures<'a> {
-        expand_or_pat(self.head()).into_iter().map(move |pat| {
+        self.head().iter_fields().map(move |pat| {
             let mut new_patstack = PatStack::from_pattern(pat);
             new_patstack.pats.extend_from_slice(&self.pats[1..]);
             new_patstack
         })
     }
 
-    /// This computes `S(self.head_ctor(), self)`. See top of the file for explanations.
+    /// This computes `S(self.head().ctor(), self)`. See top of the file for explanations.
     ///
     /// Structure patterns with a partial wild pattern (Foo { a: 42, .. }) have their missing
     /// fields filled with wild patterns.
     ///
     /// This is roughly the inverse of `Constructor::apply`.
-    fn pop_head_constructor(&self, ctor_wild_subpatterns: &Fields<'p, 'tcx>) -> PatStack<'p, 'tcx> {
+    fn pop_head_constructor(
+        &self,
+        cx: &MatchCheckCtxt<'p, 'tcx>,
+        ctor: &Constructor<'tcx>,
+    ) -> PatStack<'p, 'tcx> {
         // We pop the head pattern and push the new fields extracted from the arguments of
         // `self.head()`.
-        let mut new_fields =
-            ctor_wild_subpatterns.replace_with_pattern_arguments(self.head()).into_patterns();
+        let mut new_fields: SmallVec<[_; 2]> = self.head().specialize(cx, ctor);
         new_fields.extend_from_slice(&self.pats[1..]);
         PatStack::from_vec(new_fields)
     }
 }
 
-impl<'p, 'tcx> Default for PatStack<'p, 'tcx> {
-    fn default() -> Self {
-        Self::from_vec(smallvec![])
-    }
-}
-
-impl<'p, 'tcx> PartialEq for PatStack<'p, 'tcx> {
-    fn eq(&self, other: &Self) -> bool {
-        self.pats == other.pats
-    }
-}
-
-impl<'p, 'tcx> FromIterator<&'p Pat<'tcx>> for PatStack<'p, 'tcx> {
-    fn from_iter<T>(iter: T) -> Self
-    where
-        T: IntoIterator<Item = &'p Pat<'tcx>>,
-    {
-        Self::from_vec(iter.into_iter().collect())
-    }
-}
-
 /// Pretty-printing for matrix row.
 impl<'p, 'tcx> fmt::Debug for PatStack<'p, 'tcx> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "+")?;
         for pat in self.iter() {
-            write!(f, " {} +", pat)?;
+            write!(f, " {:?} +", pat)?;
         }
         Ok(())
     }
 }
 
 /// A 2D matrix.
-#[derive(Clone, PartialEq)]
+#[derive(Clone)]
 pub(super) struct Matrix<'p, 'tcx> {
     patterns: Vec<PatStack<'p, 'tcx>>,
 }
@@ -528,7 +442,7 @@ impl<'p, 'tcx> Matrix<'p, 'tcx> {
     /// Pushes a new row to the matrix. If the row starts with an or-pattern, this recursively
     /// expands it.
     fn push(&mut self, row: PatStack<'p, 'tcx>) {
-        if !row.is_empty() && is_or_pat(row.head()) {
+        if !row.is_empty() && row.head().is_or_pat() {
             for row in row.expand_or_pat() {
                 self.patterns.push(row);
             }
@@ -538,24 +452,10 @@ impl<'p, 'tcx> Matrix<'p, 'tcx> {
     }
 
     /// Iterate over the first component of each row
-    fn heads<'a>(&'a self) -> impl Iterator<Item = &'a Pat<'tcx>> + Captures<'p> {
-        self.patterns.iter().map(|r| r.head())
-    }
-
-    /// Iterate over the first constructor of each row.
-    pub(super) fn head_ctors<'a>(
+    fn heads<'a>(
         &'a self,
-        cx: &'a MatchCheckCtxt<'p, 'tcx>,
-    ) -> impl Iterator<Item = &'a Constructor<'tcx>> + Captures<'p> + Clone {
-        self.patterns.iter().map(move |r| r.head_ctor(cx))
-    }
-
-    /// Iterate over the first constructor and the corresponding span of each row.
-    pub(super) fn head_ctors_and_spans<'a>(
-        &'a self,
-        cx: &'a MatchCheckCtxt<'p, 'tcx>,
-    ) -> impl Iterator<Item = (&'a Constructor<'tcx>, Span)> + Captures<'p> {
-        self.patterns.iter().map(move |r| (r.head_ctor(cx), r.head().span))
+    ) -> impl Iterator<Item = &'p DeconstructedPat<'p, 'tcx>> + Clone + Captures<'a> {
+        self.patterns.iter().map(|r| r.head())
     }
 
     /// This computes `S(constructor, self)`. See top of the file for explanations.
@@ -563,13 +463,15 @@ impl<'p, 'tcx> Matrix<'p, 'tcx> {
         &self,
         pcx: PatCtxt<'_, 'p, 'tcx>,
         ctor: &Constructor<'tcx>,
-        ctor_wild_subpatterns: &Fields<'p, 'tcx>,
     ) -> Matrix<'p, 'tcx> {
-        self.patterns
-            .iter()
-            .filter(|r| ctor.is_covered_by(pcx, r.head_ctor(pcx.cx)))
-            .map(|r| r.pop_head_constructor(ctor_wild_subpatterns))
-            .collect()
+        let mut matrix = Matrix::empty();
+        for row in &self.patterns {
+            if ctor.is_covered_by(pcx, row.head().ctor()) {
+                let new_row = row.pop_head_constructor(pcx.cx, ctor);
+                matrix.push(new_row);
+            }
+        }
+        matrix
     }
 }
 
@@ -588,7 +490,7 @@ impl<'p, 'tcx> fmt::Debug for Matrix<'p, 'tcx> {
 
         let Matrix { patterns: m, .. } = self;
         let pretty_printed_matrix: Vec<Vec<String>> =
-            m.iter().map(|row| row.iter().map(|pat| format!("{}", pat)).collect()).collect();
+            m.iter().map(|row| row.iter().map(|pat| format!("{:?}", pat)).collect()).collect();
 
         let column_count = m.iter().map(|row| row.len()).next().unwrap_or(0);
         assert!(m.iter().all(|row| row.len() == column_count));
@@ -609,296 +511,40 @@ impl<'p, 'tcx> fmt::Debug for Matrix<'p, 'tcx> {
     }
 }
 
-impl<'p, 'tcx> FromIterator<PatStack<'p, 'tcx>> for Matrix<'p, 'tcx> {
-    fn from_iter<T>(iter: T) -> Self
-    where
-        T: IntoIterator<Item = PatStack<'p, 'tcx>>,
-    {
-        let mut matrix = Matrix::empty();
-        for x in iter {
-            // Using `push` ensures we correctly expand or-patterns.
-            matrix.push(x);
-        }
-        matrix
-    }
-}
-
-/// Given a pattern or a pattern-stack, this struct captures a set of its subpatterns. We use that
-/// to track reachable sub-patterns arising from or-patterns. In the absence of or-patterns this
-/// will always be either `Empty` (the whole pattern is unreachable) or `Full` (the whole pattern
-/// is reachable). When there are or-patterns, some subpatterns may be reachable while others
-/// aren't. In this case the whole pattern still counts as reachable, but we will lint the
-/// unreachable subpatterns.
-///
-/// This supports a limited set of operations, so not all possible sets of subpatterns can be
-/// represented. That's ok, we only want the ones that make sense for our usage.
-///
-/// What we're doing is illustrated by this:
-/// ```
-/// match (true, 0) {
-///     (true, 0) => {}
-///     (_, 1) => {}
-///     (true | false, 0 | 1) => {}
-/// }
-/// ```
-/// When we try the alternatives of the `true | false` or-pattern, the last `0` is reachable in the
-/// `false` alternative but not the `true`. So overall it is reachable. By contrast, the last `1`
-/// is not reachable in either alternative, so we want to signal this to the user.
-/// Therefore we take the union of sets of reachable patterns coming from different alternatives in
-/// order to figure out which subpatterns are overall reachable.
-///
-/// Invariant: we try to construct the smallest representation we can. In particular if
-/// `self.is_empty()` we ensure that `self` is `Empty`, and same with `Full`. This is not important
-/// for correctness currently.
-#[derive(Debug, Clone)]
-enum SubPatSet<'p, 'tcx> {
-    /// The empty set. This means the pattern is unreachable.
-    Empty,
-    /// The set containing the full pattern.
-    Full,
-    /// If the pattern is a pattern with a constructor or a pattern-stack, we store a set for each
-    /// of its subpatterns. Missing entries in the map are implicitly full, because that's the
-    /// common case.
-    Seq { subpats: FxHashMap<usize, SubPatSet<'p, 'tcx>> },
-    /// If the pattern is an or-pattern, we store a set for each of its alternatives. Missing
-    /// entries in the map are implicitly empty. Note: we always flatten nested or-patterns.
-    Alt {
-        subpats: FxHashMap<usize, SubPatSet<'p, 'tcx>>,
-        /// Counts the total number of alternatives in the pattern
-        alt_count: usize,
-        /// We keep the pattern around to retrieve spans.
-        pat: &'p Pat<'tcx>,
-    },
-}
-
-impl<'p, 'tcx> SubPatSet<'p, 'tcx> {
-    fn full() -> Self {
-        SubPatSet::Full
-    }
-    fn empty() -> Self {
-        SubPatSet::Empty
-    }
-
-    fn is_empty(&self) -> bool {
-        match self {
-            SubPatSet::Empty => true,
-            SubPatSet::Full => false,
-            // If any subpattern in a sequence is unreachable, the whole pattern is unreachable.
-            SubPatSet::Seq { subpats } => subpats.values().any(|set| set.is_empty()),
-            // An or-pattern is reachable if any of its alternatives is.
-            SubPatSet::Alt { subpats, .. } => subpats.values().all(|set| set.is_empty()),
-        }
-    }
-
-    fn is_full(&self) -> bool {
-        match self {
-            SubPatSet::Empty => false,
-            SubPatSet::Full => true,
-            // The whole pattern is reachable only when all its alternatives are.
-            SubPatSet::Seq { subpats } => subpats.values().all(|sub_set| sub_set.is_full()),
-            // The whole or-pattern is reachable only when all its alternatives are.
-            SubPatSet::Alt { subpats, alt_count, .. } => {
-                subpats.len() == *alt_count && subpats.values().all(|set| set.is_full())
-            }
-        }
-    }
-
-    /// Union `self` with `other`, mutating `self`.
-    fn union(&mut self, other: Self) {
-        use SubPatSet::*;
-        // Union with full stays full; union with empty changes nothing.
-        if self.is_full() || other.is_empty() {
-            return;
-        } else if self.is_empty() {
-            *self = other;
-            return;
-        } else if other.is_full() {
-            *self = Full;
-            return;
-        }
-
-        match (&mut *self, other) {
-            (Seq { subpats: s_set }, Seq { subpats: mut o_set }) => {
-                s_set.retain(|i, s_sub_set| {
-                    // Missing entries count as full.
-                    let o_sub_set = o_set.remove(&i).unwrap_or(Full);
-                    s_sub_set.union(o_sub_set);
-                    // We drop full entries.
-                    !s_sub_set.is_full()
-                });
-                // Everything left in `o_set` is missing from `s_set`, i.e. counts as full. Since
-                // unioning with full returns full, we can drop those entries.
-            }
-            (Alt { subpats: s_set, .. }, Alt { subpats: mut o_set, .. }) => {
-                s_set.retain(|i, s_sub_set| {
-                    // Missing entries count as empty.
-                    let o_sub_set = o_set.remove(&i).unwrap_or(Empty);
-                    s_sub_set.union(o_sub_set);
-                    // We drop empty entries.
-                    !s_sub_set.is_empty()
-                });
-                // Everything left in `o_set` is missing from `s_set`, i.e. counts as empty. Since
-                // unioning with empty changes nothing, we can take those entries as is.
-                s_set.extend(o_set);
-            }
-            _ => bug!(),
-        }
-
-        if self.is_full() {
-            *self = Full;
-        }
-    }
-
-    /// Returns a list of the spans of the unreachable subpatterns. If `self` is empty (i.e. the
-    /// whole pattern is unreachable) we return `None`.
-    fn list_unreachable_spans(&self) -> Option<Vec<Span>> {
-        /// Panics if `set.is_empty()`.
-        fn fill_spans(set: &SubPatSet<'_, '_>, spans: &mut Vec<Span>) {
-            match set {
-                SubPatSet::Empty => bug!(),
-                SubPatSet::Full => {}
-                SubPatSet::Seq { subpats } => {
-                    for (_, sub_set) in subpats {
-                        fill_spans(sub_set, spans);
-                    }
-                }
-                SubPatSet::Alt { subpats, pat, alt_count, .. } => {
-                    let expanded = expand_or_pat(pat);
-                    for i in 0..*alt_count {
-                        let sub_set = subpats.get(&i).unwrap_or(&SubPatSet::Empty);
-                        if sub_set.is_empty() {
-                            // Found an unreachable subpattern.
-                            spans.push(expanded[i].span);
-                        } else {
-                            fill_spans(sub_set, spans);
-                        }
-                    }
-                }
-            }
-        }
-
-        if self.is_empty() {
-            return None;
-        }
-        if self.is_full() {
-            // No subpatterns are unreachable.
-            return Some(Vec::new());
-        }
-        let mut spans = Vec::new();
-        fill_spans(self, &mut spans);
-        Some(spans)
-    }
-
-    /// When `self` refers to a patstack that was obtained from specialization, after running
-    /// `unspecialize` it will refer to the original patstack before specialization.
-    fn unspecialize(self, arity: usize) -> Self {
-        use SubPatSet::*;
-        match self {
-            Full => Full,
-            Empty => Empty,
-            Seq { subpats } => {
-                // We gather the first `arity` subpatterns together and shift the remaining ones.
-                let mut new_subpats = FxHashMap::default();
-                let mut new_subpats_first_col = FxHashMap::default();
-                for (i, sub_set) in subpats {
-                    if i < arity {
-                        // The first `arity` indices are now part of the pattern in the first
-                        // column.
-                        new_subpats_first_col.insert(i, sub_set);
-                    } else {
-                        // Indices after `arity` are simply shifted
-                        new_subpats.insert(i - arity + 1, sub_set);
-                    }
-                }
-                // If `new_subpats_first_col` has no entries it counts as full, so we can omit it.
-                if !new_subpats_first_col.is_empty() {
-                    new_subpats.insert(0, Seq { subpats: new_subpats_first_col });
-                }
-                Seq { subpats: new_subpats }
-            }
-            Alt { .. } => bug!(), // `self` is a patstack
-        }
-    }
-
-    /// When `self` refers to a patstack that was obtained from splitting an or-pattern, after
-    /// running `unspecialize` it will refer to the original patstack before splitting.
-    ///
-    /// For example:
-    /// ```
-    /// match Some(true) {
-    ///     Some(true) => {}
-    ///     None | Some(true | false) => {}
-    /// }
-    /// ```
-    /// Here `None` would return the full set and `Some(true | false)` would return the set
-    /// containing `false`. After `unsplit_or_pat`, we want the set to contain `None` and `false`.
-    /// This is what this function does.
-    fn unsplit_or_pat(mut self, alt_id: usize, alt_count: usize, pat: &'p Pat<'tcx>) -> Self {
-        use SubPatSet::*;
-        if self.is_empty() {
-            return Empty;
-        }
-
-        // Subpatterns coming from inside the or-pattern alternative itself, e.g. in `None | Some(0
-        // | 1)`.
-        let set_first_col = match &mut self {
-            Full => Full,
-            Seq { subpats } => subpats.remove(&0).unwrap_or(Full),
-            Empty => unreachable!(),
-            Alt { .. } => bug!(), // `self` is a patstack
-        };
-        let mut subpats_first_col = FxHashMap::default();
-        subpats_first_col.insert(alt_id, set_first_col);
-        let set_first_col = Alt { subpats: subpats_first_col, pat, alt_count };
-
-        let mut subpats = match self {
-            Full => FxHashMap::default(),
-            Seq { subpats } => subpats,
-            Empty => unreachable!(),
-            Alt { .. } => bug!(), // `self` is a patstack
-        };
-        subpats.insert(0, set_first_col);
-        Seq { subpats }
-    }
-}
-
 /// This carries the results of computing usefulness, as described at the top of the file. When
 /// checking usefulness of a match branch, we use the `NoWitnesses` variant, which also keeps track
 /// of potential unreachable sub-patterns (in the presence of or-patterns). When checking
 /// exhaustiveness of a whole match, we use the `WithWitnesses` variant, which carries a list of
 /// witnesses of non-exhaustiveness when there are any.
 /// Which variant to use is dictated by `ArmType`.
-#[derive(Clone, Debug)]
+#[derive(Debug)]
 enum Usefulness<'p, 'tcx> {
-    /// Carries a set of subpatterns that have been found to be reachable. If empty, this indicates
-    /// the whole pattern is unreachable. If not, this indicates that the pattern is reachable but
-    /// that some sub-patterns may be unreachable (due to or-patterns). In the absence of
-    /// or-patterns this will always be either `Empty` (the whole pattern is unreachable) or `Full`
-    /// (the whole pattern is reachable).
-    NoWitnesses(SubPatSet<'p, 'tcx>),
+    /// If we don't care about witnesses, simply remember if the pattern was useful.
+    NoWitnesses { useful: bool },
     /// Carries a list of witnesses of non-exhaustiveness. If empty, indicates that the whole
     /// pattern is unreachable.
-    WithWitnesses(Vec<Witness<'tcx>>),
+    WithWitnesses(Vec<Witness<'p, 'tcx>>),
 }
 
 impl<'p, 'tcx> Usefulness<'p, 'tcx> {
     fn new_useful(preference: ArmType) -> Self {
         match preference {
+            // A single (empty) witness of reachability.
             FakeExtraWildcard => WithWitnesses(vec![Witness(vec![])]),
-            RealArm => NoWitnesses(SubPatSet::full()),
+            RealArm => NoWitnesses { useful: true },
         }
     }
 
     fn new_not_useful(preference: ArmType) -> Self {
         match preference {
             FakeExtraWildcard => WithWitnesses(vec![]),
-            RealArm => NoWitnesses(SubPatSet::empty()),
+            RealArm => NoWitnesses { useful: false },
         }
     }
 
     fn is_useful(&self) -> bool {
         match self {
-            Usefulness::NoWitnesses(set) => !set.is_empty(),
+            Usefulness::NoWitnesses { useful } => *useful,
             Usefulness::WithWitnesses(witnesses) => !witnesses.is_empty(),
         }
     }
@@ -909,33 +555,10 @@ impl<'p, 'tcx> Usefulness<'p, 'tcx> {
             (WithWitnesses(_), WithWitnesses(o)) if o.is_empty() => {}
             (WithWitnesses(s), WithWitnesses(o)) if s.is_empty() => *self = WithWitnesses(o),
             (WithWitnesses(s), WithWitnesses(o)) => s.extend(o),
-            (NoWitnesses(s), NoWitnesses(o)) => s.union(o),
-            _ => unreachable!(),
-        }
-    }
-
-    /// When trying several branches and each returns a `Usefulness`, we need to combine the
-    /// results together.
-    fn merge(pref: ArmType, usefulnesses: impl Iterator<Item = Self>) -> Self {
-        let mut ret = Self::new_not_useful(pref);
-        for u in usefulnesses {
-            ret.extend(u);
-            if let NoWitnesses(subpats) = &ret {
-                if subpats.is_full() {
-                    // Once we reach the full set, more unions won't change the result.
-                    return ret;
-                }
+            (NoWitnesses { useful: s_useful }, NoWitnesses { useful: o_useful }) => {
+                *s_useful = *s_useful || o_useful
             }
-        }
-        ret
-    }
-
-    /// After calculating the usefulness for a branch of an or-pattern, call this to make this
-    /// usefulness mergeable with those from the other branches.
-    fn unsplit_or_pat(self, alt_id: usize, alt_count: usize, pat: &'p Pat<'tcx>) -> Self {
-        match self {
-            NoWitnesses(subpats) => NoWitnesses(subpats.unsplit_or_pat(alt_id, alt_count, pat)),
-            WithWitnesses(_) => bug!(),
+            _ => unreachable!(),
         }
     }
 
@@ -947,10 +570,10 @@ impl<'p, 'tcx> Usefulness<'p, 'tcx> {
         pcx: PatCtxt<'_, 'p, 'tcx>,
         matrix: &Matrix<'p, 'tcx>, // used to compute missing ctors
         ctor: &Constructor<'tcx>,
-        ctor_wild_subpatterns: &Fields<'p, 'tcx>,
     ) -> Self {
         match self {
-            WithWitnesses(witnesses) if witnesses.is_empty() => WithWitnesses(witnesses),
+            NoWitnesses { .. } => self,
+            WithWitnesses(ref witnesses) if witnesses.is_empty() => self,
             WithWitnesses(witnesses) => {
                 let new_witnesses = if let Constructor::Missing { .. } = ctor {
                     // We got the special `Missing` constructor, so each of the missing constructors
@@ -958,22 +581,18 @@ impl<'p, 'tcx> Usefulness<'p, 'tcx> {
                     let new_patterns = if pcx.is_non_exhaustive {
                         // Here we don't want the user to try to list all variants, we want them to add
                         // a wildcard, so we only suggest that.
-                        vec![
-                            Fields::wildcards(pcx, &Constructor::NonExhaustive)
-                                .apply(pcx, &Constructor::NonExhaustive),
-                        ]
+                        vec![DeconstructedPat::wildcard(pcx.ty)]
                     } else {
                         let mut split_wildcard = SplitWildcard::new(pcx);
-                        split_wildcard.split(pcx, matrix.head_ctors(pcx.cx));
+                        split_wildcard.split(pcx, matrix.heads().map(DeconstructedPat::ctor));
                         // Construct for each missing constructor a "wild" version of this
                         // constructor, that matches everything that can be built with
                         // it. For example, if `ctor` is a `Constructor::Variant` for
                         // `Option::Some`, we get the pattern `Some(_)`.
                         split_wildcard
                             .iter_missing(pcx)
-                            .map(|missing_ctor| {
-                                Fields::wildcards(pcx, missing_ctor).apply(pcx, missing_ctor)
-                            })
+                            .cloned()
+                            .map(|missing_ctor| DeconstructedPat::wild_from_ctor(pcx, missing_ctor))
                             .collect()
                     };
 
@@ -981,21 +600,25 @@ impl<'p, 'tcx> Usefulness<'p, 'tcx> {
                         .into_iter()
                         .flat_map(|witness| {
                             new_patterns.iter().map(move |pat| {
-                                let mut witness = witness.clone();
-                                witness.0.push(pat.clone());
-                                witness
+                                Witness(
+                                    witness
+                                        .0
+                                        .iter()
+                                        .chain(once(pat))
+                                        .map(DeconstructedPat::clone_and_forget_reachability)
+                                        .collect(),
+                                )
                             })
                         })
                         .collect()
                 } else {
                     witnesses
                         .into_iter()
-                        .map(|witness| witness.apply_constructor(pcx, &ctor, ctor_wild_subpatterns))
+                        .map(|witness| witness.apply_constructor(pcx, &ctor))
                         .collect()
                 };
                 WithWitnesses(new_witnesses)
             }
-            NoWitnesses(subpats) => NoWitnesses(subpats.unspecialize(ctor_wild_subpatterns.len())),
         }
     }
 }
@@ -1039,12 +662,12 @@ enum ArmType {
 ///     `Witness(vec![Pair(Some(_), true)])`
 ///
 /// The final `Pair(Some(_), true)` is then the resulting witness.
-#[derive(Clone, Debug)]
-crate struct Witness<'tcx>(Vec<Pat<'tcx>>);
+#[derive(Debug)]
+crate struct Witness<'p, 'tcx>(Vec<DeconstructedPat<'p, 'tcx>>);
 
-impl<'tcx> Witness<'tcx> {
+impl<'p, 'tcx> Witness<'p, 'tcx> {
     /// Asserts that the witness contains a single pattern, and returns it.
-    fn single_pattern(self) -> Pat<'tcx> {
+    fn single_pattern(self) -> DeconstructedPat<'p, 'tcx> {
         assert_eq!(self.0.len(), 1);
         self.0.into_iter().next().unwrap()
     }
@@ -1062,17 +685,13 @@ impl<'tcx> Witness<'tcx> {
     ///
     /// left_ty: struct X { a: (bool, &'static str), b: usize}
     /// pats: [(false, "foo"), 42]  => X { a: (false, "foo"), b: 42 }
-    fn apply_constructor<'p>(
-        mut self,
-        pcx: PatCtxt<'_, 'p, 'tcx>,
-        ctor: &Constructor<'tcx>,
-        ctor_wild_subpatterns: &Fields<'p, 'tcx>,
-    ) -> Self {
+    fn apply_constructor(mut self, pcx: PatCtxt<'_, 'p, 'tcx>, ctor: &Constructor<'tcx>) -> Self {
         let pat = {
             let len = self.0.len();
-            let arity = ctor_wild_subpatterns.len();
+            let arity = ctor.arity(pcx);
             let pats = self.0.drain((len - arity)..).rev();
-            ctor_wild_subpatterns.replace_fields(pcx.cx, pats).apply(pcx, ctor)
+            let fields = Fields::from_iter(pcx.cx, pats);
+            DeconstructedPat::new(ctor.clone(), fields, pcx.ty, DUMMY_SP)
         };
 
         self.0.push(pat);
@@ -1090,9 +709,9 @@ fn lint_non_exhaustive_omitted_patterns<'p, 'tcx>(
     scrut_ty: Ty<'tcx>,
     sp: Span,
     hir_id: HirId,
-    witnesses: Vec<Pat<'tcx>>,
+    witnesses: Vec<DeconstructedPat<'p, 'tcx>>,
 ) {
-    let joined_patterns = joined_uncovered_patterns(&witnesses);
+    let joined_patterns = joined_uncovered_patterns(cx, &witnesses);
     cx.tcx.struct_span_lint_hir(NON_EXHAUSTIVE_OMITTED_PATTERNS, hir_id, sp, |build| {
         let mut lint = build.build("some variants are not matched explicitly");
         lint.span_label(sp, pattern_not_covered_label(&witnesses, &joined_patterns));
@@ -1163,56 +782,52 @@ fn is_useful<'p, 'tcx>(
     assert!(rows.iter().all(|r| r.len() == v.len()));
 
     // FIXME(Nadrieril): Hack to work around type normalization issues (see #72476).
-    let ty = matrix.heads().next().map_or(v.head().ty, |r| r.ty);
+    let ty = matrix.heads().next().map_or(v.head().ty(), |r| r.ty());
     let is_non_exhaustive = cx.is_foreign_non_exhaustive_enum(ty);
-    let pcx = PatCtxt { cx, ty, span: v.head().span, is_top_level, is_non_exhaustive };
+    let pcx = PatCtxt { cx, ty, span: v.head().span(), is_top_level, is_non_exhaustive };
 
     // If the first pattern is an or-pattern, expand it.
-    let ret = if is_or_pat(v.head()) {
+    let mut ret = Usefulness::new_not_useful(witness_preference);
+    if v.head().is_or_pat() {
         debug!("expanding or-pattern");
-        let v_head = v.head();
-        let vs: Vec<_> = v.expand_or_pat().collect();
-        let alt_count = vs.len();
         // We try each or-pattern branch in turn.
         let mut matrix = matrix.clone();
-        let usefulnesses = vs.into_iter().enumerate().map(|(i, v)| {
+        for v in v.expand_or_pat() {
             let usefulness =
                 is_useful(cx, &matrix, &v, witness_preference, hir_id, is_under_guard, false);
+            ret.extend(usefulness);
             // If pattern has a guard don't add it to the matrix.
             if !is_under_guard {
                 // We push the already-seen patterns into the matrix in order to detect redundant
                 // branches like `Some(_) | Some(0)`.
                 matrix.push(v);
             }
-            usefulness.unsplit_or_pat(i, alt_count, v_head)
-        });
-        Usefulness::merge(witness_preference, usefulnesses)
+        }
     } else {
-        let v_ctor = v.head_ctor(cx);
+        let v_ctor = v.head().ctor();
         if let Constructor::IntRange(ctor_range) = &v_ctor {
             // Lint on likely incorrect range patterns (#63987)
             ctor_range.lint_overlapping_range_endpoints(
                 pcx,
-                matrix.head_ctors_and_spans(cx),
+                matrix.heads(),
                 matrix.column_count().unwrap_or(0),
                 hir_id,
             )
         }
         // We split the head constructor of `v`.
-        let split_ctors = v_ctor.split(pcx, matrix.head_ctors(cx));
+        let split_ctors = v_ctor.split(pcx, matrix.heads().map(DeconstructedPat::ctor));
         let is_non_exhaustive_and_wild = is_non_exhaustive && v_ctor.is_wildcard();
         // For each constructor, we compute whether there's a value that starts with it that would
         // witness the usefulness of `v`.
         let start_matrix = &matrix;
-        let usefulnesses = split_ctors.into_iter().map(|ctor| {
+        for ctor in split_ctors {
             debug!("specialize({:?})", ctor);
             // We cache the result of `Fields::wildcards` because it is used a lot.
-            let ctor_wild_subpatterns = Fields::wildcards(pcx, &ctor);
-            let spec_matrix =
-                start_matrix.specialize_constructor(pcx, &ctor, &ctor_wild_subpatterns);
-            let v = v.pop_head_constructor(&ctor_wild_subpatterns);
+            let spec_matrix = start_matrix.specialize_constructor(pcx, &ctor);
+            let v = v.pop_head_constructor(cx, &ctor);
             let usefulness =
                 is_useful(cx, &spec_matrix, &v, witness_preference, hir_id, is_under_guard, false);
+            let usefulness = usefulness.apply_constructor(pcx, start_matrix, &ctor);
 
             // When all the conditions are met we have a match with a `non_exhaustive` enum
             // that has the potential to trigger the `non_exhaustive_omitted_patterns` lint.
@@ -1229,29 +844,31 @@ fn is_useful<'p, 'tcx>(
             {
                 let patterns = {
                     let mut split_wildcard = SplitWildcard::new(pcx);
-                    split_wildcard.split(pcx, matrix.head_ctors(pcx.cx));
+                    split_wildcard.split(pcx, matrix.heads().map(DeconstructedPat::ctor));
                     // Construct for each missing constructor a "wild" version of this
                     // constructor, that matches everything that can be built with
                     // it. For example, if `ctor` is a `Constructor::Variant` for
                     // `Option::Some`, we get the pattern `Some(_)`.
                     split_wildcard
                         .iter_missing(pcx)
-                        // Filter out the `Constructor::NonExhaustive` variant it's meaningless
-                        // to our lint
+                        // Filter out the `NonExhaustive` because we want to list only real
+                        // variants.
                         .filter(|c| !c.is_non_exhaustive())
-                        .map(|missing_ctor| {
-                            Fields::wildcards(pcx, missing_ctor).apply(pcx, missing_ctor)
-                        })
+                        .cloned()
+                        .map(|missing_ctor| DeconstructedPat::wild_from_ctor(pcx, missing_ctor))
                         .collect::<Vec<_>>()
                 };
 
                 lint_non_exhaustive_omitted_patterns(pcx.cx, pcx.ty, pcx.span, hir_id, patterns);
             }
 
-            usefulness.apply_constructor(pcx, start_matrix, &ctor, &ctor_wild_subpatterns)
-        });
-        Usefulness::merge(witness_preference, usefulnesses)
-    };
+            ret.extend(usefulness);
+        }
+    }
+
+    if ret.is_useful() {
+        v.head().set_reachable();
+    }
 
     debug!(?ret);
     ret
@@ -1261,7 +878,7 @@ fn is_useful<'p, 'tcx>(
 #[derive(Clone, Copy)]
 crate struct MatchArm<'p, 'tcx> {
     /// The pattern must have been lowered through `check_match::MatchVisitor::lower_pattern`.
-    crate pat: &'p Pat<'tcx>,
+    crate pat: &'p DeconstructedPat<'p, 'tcx>,
     crate hir_id: HirId,
     crate has_guard: bool,
 }
@@ -1283,7 +900,7 @@ crate struct UsefulnessReport<'p, 'tcx> {
     crate arm_usefulness: Vec<(MatchArm<'p, 'tcx>, Reachability)>,
     /// If the match is exhaustive, this is empty. If not, this contains witnesses for the lack of
     /// exhaustiveness.
-    crate non_exhaustiveness_witnesses: Vec<Pat<'tcx>>,
+    crate non_exhaustiveness_witnesses: Vec<DeconstructedPat<'p, 'tcx>>,
 }
 
 /// The entrypoint for the usefulness algorithm. Computes whether a match is exhaustive and which
@@ -1303,27 +920,25 @@ crate fn compute_match_usefulness<'p, 'tcx>(
         .copied()
         .map(|arm| {
             let v = PatStack::from_pattern(arm.pat);
-            let usefulness = is_useful(cx, &matrix, &v, RealArm, arm.hir_id, arm.has_guard, true);
+            is_useful(cx, &matrix, &v, RealArm, arm.hir_id, arm.has_guard, true);
             if !arm.has_guard {
                 matrix.push(v);
             }
-            let reachability = match usefulness {
-                NoWitnesses(subpats) if subpats.is_empty() => Reachability::Unreachable,
-                NoWitnesses(subpats) => {
-                    Reachability::Reachable(subpats.list_unreachable_spans().unwrap())
-                }
-                WithWitnesses(..) => bug!(),
+            let reachability = if arm.pat.is_reachable() {
+                Reachability::Reachable(arm.pat.unreachable_spans())
+            } else {
+                Reachability::Unreachable
             };
             (arm, reachability)
         })
         .collect();
 
-    let wild_pattern = cx.pattern_arena.alloc(Pat::wildcard_from_ty(scrut_ty));
+    let wild_pattern = cx.pattern_arena.alloc(DeconstructedPat::wildcard(scrut_ty));
     let v = PatStack::from_pattern(wild_pattern);
     let usefulness = is_useful(cx, &matrix, &v, FakeExtraWildcard, scrut_hir_id, false, true);
     let non_exhaustiveness_witnesses = match usefulness {
         WithWitnesses(pats) => pats.into_iter().map(|w| w.single_pattern()).collect(),
-        NoWitnesses(_) => bug!(),
+        NoWitnesses { .. } => bug!(),
     };
     UsefulnessReport { arm_usefulness, non_exhaustiveness_witnesses }
 }
diff --git a/compiler/rustc_mir_dataflow/src/impls/mod.rs b/compiler/rustc_mir_dataflow/src/impls/mod.rs
index 771ad90af28..474f4f2a79b 100644
--- a/compiler/rustc_mir_dataflow/src/impls/mod.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/mod.rs
@@ -602,6 +602,7 @@ impl<'tcx> AnalysisDomain<'tcx> for EverInitializedPlaces<'_, 'tcx> {
 impl<'tcx> GenKillAnalysis<'tcx> for EverInitializedPlaces<'_, 'tcx> {
     type Idx = InitIndex;
 
+    #[instrument(skip(self, trans), level = "debug")]
     fn statement_effect(
         &self,
         trans: &mut impl GenKill<Self::Idx>,
@@ -613,24 +614,19 @@ impl<'tcx> GenKillAnalysis<'tcx> for EverInitializedPlaces<'_, 'tcx> {
         let init_loc_map = &move_data.init_loc_map;
         let rev_lookup = &move_data.rev_lookup;
 
-        debug!(
-            "statement {:?} at loc {:?} initializes move_indexes {:?}",
-            stmt, location, &init_loc_map[location]
-        );
+        debug!("initializes move_indexes {:?}", &init_loc_map[location]);
         trans.gen_all(init_loc_map[location].iter().copied());
 
         if let mir::StatementKind::StorageDead(local) = stmt.kind {
             // End inits for StorageDead, so that an immutable variable can
             // be reinitialized on the next iteration of the loop.
             let move_path_index = rev_lookup.find_local(local);
-            debug!(
-                "stmt {:?} at loc {:?} clears the ever initialized status of {:?}",
-                stmt, location, &init_path_map[move_path_index]
-            );
+            debug!("clears the ever initialized status of {:?}", init_path_map[move_path_index]);
             trans.kill_all(init_path_map[move_path_index].iter().copied());
         }
     }
 
+    #[instrument(skip(self, trans, _terminator), level = "debug")]
     fn terminator_effect(
         &self,
         trans: &mut impl GenKill<Self::Idx>,
@@ -640,10 +636,8 @@ impl<'tcx> GenKillAnalysis<'tcx> for EverInitializedPlaces<'_, 'tcx> {
         let (body, move_data) = (self.body, self.move_data());
         let term = body[location.block].terminator();
         let init_loc_map = &move_data.init_loc_map;
-        debug!(
-            "terminator {:?} at loc {:?} initializes move_indexes {:?}",
-            term, location, &init_loc_map[location]
-        );
+        debug!(?term);
+        debug!("initializes move_indexes {:?}", init_loc_map[location]);
         trans.gen_all(
             init_loc_map[location]
                 .iter()
diff --git a/compiler/rustc_mir_transform/src/generator.rs b/compiler/rustc_mir_transform/src/generator.rs
index 06366b6fc31..bc72e9d94a9 100644
--- a/compiler/rustc_mir_transform/src/generator.rs
+++ b/compiler/rustc_mir_transform/src/generator.rs
@@ -342,7 +342,7 @@ impl MutVisitor<'tcx> for TransformVisitor<'tcx> {
             let source_info = data.terminator().source_info;
             // We must assign the value first in case it gets declared dead below
             data.statements.extend(self.make_state(state_idx, v, source_info));
-            let state = if let Some((resume, resume_arg)) = resume {
+            let state = if let Some((resume, mut resume_arg)) = resume {
                 // Yield
                 let state = 3 + self.suspension_points.len();
 
@@ -350,7 +350,8 @@ impl MutVisitor<'tcx> for TransformVisitor<'tcx> {
                 // live across a yield.
                 let resume_arg =
                     if let Some(&(ty, variant, idx)) = self.remap.get(&resume_arg.local) {
-                        self.make_field(variant, idx, ty)
+                        replace_base(&mut resume_arg, self.make_field(variant, idx, ty), self.tcx);
+                        resume_arg
                     } else {
                         resume_arg
                     };
diff --git a/compiler/rustc_parse/src/parser/path.rs b/compiler/rustc_parse/src/parser/path.rs
index 953c6915068..c7d080a80fe 100644
--- a/compiler/rustc_parse/src/parser/path.rs
+++ b/compiler/rustc_parse/src/parser/path.rs
@@ -495,20 +495,28 @@ impl<'a> Parser<'a> {
             None => {
                 let after_eq = eq.shrink_to_hi();
                 let before_next = self.token.span.shrink_to_lo();
-                self.struct_span_err(after_eq.to(before_next), "missing type to the right of `=`")
-                    .span_suggestion(
+                let mut err = self
+                    .struct_span_err(after_eq.to(before_next), "missing type to the right of `=`");
+                if matches!(self.token.kind, token::Comma | token::Gt) {
+                    err.span_suggestion(
                         self.sess.source_map().next_point(eq).to(before_next),
                         "to constrain the associated type, add a type after `=`",
                         " TheType".to_string(),
                         Applicability::HasPlaceholders,
-                    )
-                    .span_suggestion(
+                    );
+                    err.span_suggestion(
                         eq.to(before_next),
                         &format!("remove the `=` if `{}` is a type", ident),
                         String::new(),
                         Applicability::MaybeIncorrect,
                     )
-                    .emit();
+                } else {
+                    err.span_label(
+                        self.token.span,
+                        &format!("expected type, found {}", super::token_descr(&self.token)),
+                    )
+                };
+                return Err(err);
             }
         }
         Ok(self.mk_ty(span, ast::TyKind::Err))
@@ -572,6 +580,25 @@ impl<'a> Parser<'a> {
                     return self.recover_const_arg(start, err).map(Some);
                 }
             }
+        } else if self.eat_keyword_noexpect(kw::Const) {
+            // Detect and recover from the old, pre-RFC2000 syntax for const generics.
+            let mut err = self.struct_span_err(
+                start,
+                "expected lifetime, type, or constant, found keyword `const`",
+            );
+            if self.check_const_arg() {
+                err.span_suggestion_verbose(
+                    start.until(self.token.span),
+                    "the `const` keyword is only needed in the definition of the type",
+                    String::new(),
+                    Applicability::MaybeIncorrect,
+                );
+                err.emit();
+                GenericArg::Const(self.parse_const_arg()?)
+            } else {
+                let after_kw_const = self.token.span;
+                return self.recover_const_arg(after_kw_const, err).map(Some);
+            }
         } else {
             return Ok(None);
         };
diff --git a/compiler/rustc_resolve/src/diagnostics.rs b/compiler/rustc_resolve/src/diagnostics.rs
index d6ff5a7e90b..ab1f47c81db 100644
--- a/compiler/rustc_resolve/src/diagnostics.rs
+++ b/compiler/rustc_resolve/src/diagnostics.rs
@@ -198,7 +198,7 @@ impl<'a> Resolver<'a> {
                 err.span_label(first_use_span, format!("first use of `{}`", name));
                 err
             }
-            ResolutionError::MethodNotMemberOfTrait(method, trait_) => {
+            ResolutionError::MethodNotMemberOfTrait(method, trait_, candidate) => {
                 let mut err = struct_span_err!(
                     self.session,
                     span,
@@ -208,9 +208,17 @@ impl<'a> Resolver<'a> {
                     trait_
                 );
                 err.span_label(span, format!("not a member of trait `{}`", trait_));
+                if let Some(candidate) = candidate {
+                    err.span_suggestion(
+                        method.span,
+                        "there is an associated function with a similar name",
+                        candidate.to_ident_string(),
+                        Applicability::MaybeIncorrect,
+                    );
+                }
                 err
             }
-            ResolutionError::TypeNotMemberOfTrait(type_, trait_) => {
+            ResolutionError::TypeNotMemberOfTrait(type_, trait_, candidate) => {
                 let mut err = struct_span_err!(
                     self.session,
                     span,
@@ -220,9 +228,17 @@ impl<'a> Resolver<'a> {
                     trait_
                 );
                 err.span_label(span, format!("not a member of trait `{}`", trait_));
+                if let Some(candidate) = candidate {
+                    err.span_suggestion(
+                        type_.span,
+                        "there is an associated type with a similar name",
+                        candidate.to_ident_string(),
+                        Applicability::MaybeIncorrect,
+                    );
+                }
                 err
             }
-            ResolutionError::ConstNotMemberOfTrait(const_, trait_) => {
+            ResolutionError::ConstNotMemberOfTrait(const_, trait_, candidate) => {
                 let mut err = struct_span_err!(
                     self.session,
                     span,
@@ -232,6 +248,14 @@ impl<'a> Resolver<'a> {
                     trait_
                 );
                 err.span_label(span, format!("not a member of trait `{}`", trait_));
+                if let Some(candidate) = candidate {
+                    err.span_suggestion(
+                        const_.span,
+                        "there is an associated constant with a similar name",
+                        candidate.to_ident_string(),
+                        Applicability::MaybeIncorrect,
+                    );
+                }
                 err
             }
             ResolutionError::VariableNotBoundInPattern(binding_error) => {
@@ -949,7 +973,15 @@ impl<'a> Resolver<'a> {
 
         let import_suggestions =
             self.lookup_import_candidates(ident, Namespace::MacroNS, parent_scope, is_expected);
-        show_candidates(err, None, &import_suggestions, false, true);
+        show_candidates(
+            &self.definitions,
+            self.session,
+            err,
+            None,
+            &import_suggestions,
+            false,
+            true,
+        );
 
         if macro_kind == MacroKind::Derive && (ident.name == sym::Send || ident.name == sym::Sync) {
             let msg = format!("unsafe traits like `{}` should be implemented explicitly", ident);
@@ -1689,6 +1721,8 @@ fn find_span_immediately_after_crate_name(
 /// entities with that name in all crates. This method allows outputting the
 /// results of this search in a programmer-friendly way
 crate fn show_candidates(
+    definitions: &rustc_hir::definitions::Definitions,
+    session: &Session,
     err: &mut DiagnosticBuilder<'_>,
     // This is `None` if all placement locations are inside expansions
     use_placement_span: Option<Span>,
@@ -1700,43 +1734,111 @@ crate fn show_candidates(
         return;
     }
 
+    let mut accessible_path_strings: Vec<(String, &str, Option<DefId>)> = Vec::new();
+    let mut inaccessible_path_strings: Vec<(String, &str, Option<DefId>)> = Vec::new();
+
+    candidates.iter().for_each(|c| {
+        (if c.accessible { &mut accessible_path_strings } else { &mut inaccessible_path_strings })
+            .push((path_names_to_string(&c.path), c.descr, c.did))
+    });
+
     // we want consistent results across executions, but candidates are produced
     // by iterating through a hash map, so make sure they are ordered:
-    let mut path_strings: Vec<_> =
-        candidates.iter().map(|c| path_names_to_string(&c.path)).collect();
+    for path_strings in [&mut accessible_path_strings, &mut inaccessible_path_strings] {
+        path_strings.sort_by(|a, b| a.0.cmp(&b.0));
+        let core_path_strings =
+            path_strings.drain_filter(|p| p.0.starts_with("core::")).collect::<Vec<_>>();
+        path_strings.extend(core_path_strings);
+        path_strings.dedup_by(|a, b| a.0 == b.0);
+    }
 
-    path_strings.sort();
-    let core_path_strings =
-        path_strings.drain_filter(|p| p.starts_with("core::")).collect::<Vec<String>>();
-    path_strings.extend(core_path_strings);
-    path_strings.dedup();
+    if !accessible_path_strings.is_empty() {
+        let (determiner, kind) = if accessible_path_strings.len() == 1 {
+            ("this", accessible_path_strings[0].1)
+        } else {
+            ("one of these", "items")
+        };
 
-    let (determiner, kind) = if candidates.len() == 1 {
-        ("this", candidates[0].descr)
-    } else {
-        ("one of these", "items")
-    };
-
-    let instead = if instead { " instead" } else { "" };
-    let mut msg = format!("consider importing {} {}{}", determiner, kind, instead);
-
-    if let Some(span) = use_placement_span {
-        for candidate in &mut path_strings {
-            // produce an additional newline to separate the new use statement
-            // from the directly following item.
-            let additional_newline = if found_use { "" } else { "\n" };
-            *candidate = format!("use {};\n{}", candidate, additional_newline);
-        }
+        let instead = if instead { " instead" } else { "" };
+        let mut msg = format!("consider importing {} {}{}", determiner, kind, instead);
 
-        err.span_suggestions(span, &msg, path_strings.into_iter(), Applicability::Unspecified);
-    } else {
-        msg.push(':');
+        if let Some(span) = use_placement_span {
+            for candidate in &mut accessible_path_strings {
+                // produce an additional newline to separate the new use statement
+                // from the directly following item.
+                let additional_newline = if found_use { "" } else { "\n" };
+                candidate.0 = format!("use {};\n{}", &candidate.0, additional_newline);
+            }
+
+            err.span_suggestions(
+                span,
+                &msg,
+                accessible_path_strings.into_iter().map(|a| a.0),
+                Applicability::Unspecified,
+            );
+        } else {
+            msg.push(':');
+
+            for candidate in accessible_path_strings {
+                msg.push('\n');
+                msg.push_str(&candidate.0);
+            }
 
-        for candidate in path_strings {
-            msg.push('\n');
-            msg.push_str(&candidate);
+            err.note(&msg);
         }
+    } else {
+        assert!(!inaccessible_path_strings.is_empty());
+
+        if inaccessible_path_strings.len() == 1 {
+            let (name, descr, def_id) = &inaccessible_path_strings[0];
+            let msg = format!("{} `{}` exists but is inaccessible", descr, name);
+
+            if let Some(local_def_id) = def_id.and_then(|did| did.as_local()) {
+                let span = definitions.def_span(local_def_id);
+                let span = session.source_map().guess_head_span(span);
+                let mut multi_span = MultiSpan::from_span(span);
+                multi_span.push_span_label(span, "not accessible".to_string());
+                err.span_note(multi_span, &msg);
+            } else {
+                err.note(&msg);
+            }
+        } else {
+            let (_, descr_first, _) = &inaccessible_path_strings[0];
+            let descr = if inaccessible_path_strings
+                .iter()
+                .skip(1)
+                .all(|(_, descr, _)| descr == descr_first)
+            {
+                format!("{}", descr_first)
+            } else {
+                "item".to_string()
+            };
+
+            let mut msg = format!("these {}s exist but are inaccessible", descr);
+            let mut has_colon = false;
 
-        err.note(&msg);
+            let mut spans = Vec::new();
+            for (name, _, def_id) in &inaccessible_path_strings {
+                if let Some(local_def_id) = def_id.and_then(|did| did.as_local()) {
+                    let span = definitions.def_span(local_def_id);
+                    let span = session.source_map().guess_head_span(span);
+                    spans.push((name, span));
+                } else {
+                    if !has_colon {
+                        msg.push(':');
+                        has_colon = true;
+                    }
+                    msg.push('\n');
+                    msg.push_str(name);
+                }
+            }
+
+            let mut multi_span = MultiSpan::from_spans(spans.iter().map(|(_, sp)| *sp).collect());
+            for (name, span) in spans {
+                multi_span.push_span_label(span, format!("`{}`: not accessible", name));
+            }
+
+            err.span_note(multi_span, &msg);
+        }
     }
 }
diff --git a/compiler/rustc_resolve/src/late.rs b/compiler/rustc_resolve/src/late.rs
index 3c48a76224f..95633257965 100644
--- a/compiler/rustc_resolve/src/late.rs
+++ b/compiler/rustc_resolve/src/late.rs
@@ -1309,14 +1309,15 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
                                     use crate::ResolutionError::*;
                                     match &item.kind {
                                         AssocItemKind::Const(_default, _ty, _expr) => {
-                                            debug!("resolve_implementation AssocItemKind::Const",);
+                                            debug!("resolve_implementation AssocItemKind::Const");
                                             // If this is a trait impl, ensure the const
                                             // exists in trait
                                             this.check_trait_item(
                                                 item.ident,
+                                                &item.kind,
                                                 ValueNS,
                                                 item.span,
-                                                |n, s| ConstNotMemberOfTrait(n, s),
+                                                |i, s, c| ConstNotMemberOfTrait(i, s, c),
                                             );
 
                                             // We allow arbitrary const expressions inside of associated consts,
@@ -1338,6 +1339,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
                                             );
                                         }
                                         AssocItemKind::Fn(box FnKind(.., generics, _)) => {
+                                            debug!("resolve_implementation AssocItemKind::Fn");
                                             // We also need a new scope for the impl item type parameters.
                                             this.with_generic_param_rib(
                                                 generics,
@@ -1347,9 +1349,10 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
                                                     // exists in trait
                                                     this.check_trait_item(
                                                         item.ident,
+                                                        &item.kind,
                                                         ValueNS,
                                                         item.span,
-                                                        |n, s| MethodNotMemberOfTrait(n, s),
+                                                        |i, s, c| MethodNotMemberOfTrait(i, s, c),
                                                     );
 
                                                     visit::walk_assoc_item(
@@ -1366,6 +1369,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
                                             _,
                                             _,
                                         )) => {
+                                            debug!("resolve_implementation AssocItemKind::TyAlias");
                                             // We also need a new scope for the impl item type parameters.
                                             this.with_generic_param_rib(
                                                 generics,
@@ -1375,9 +1379,10 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
                                                     // exists in trait
                                                     this.check_trait_item(
                                                         item.ident,
+                                                        &item.kind,
                                                         TypeNS,
                                                         item.span,
-                                                        |n, s| TypeNotMemberOfTrait(n, s),
+                                                        |i, s, c| TypeNotMemberOfTrait(i, s, c),
                                                     );
 
                                                     visit::walk_assoc_item(
@@ -1401,9 +1406,15 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
         });
     }
 
-    fn check_trait_item<F>(&mut self, ident: Ident, ns: Namespace, span: Span, err: F)
-    where
-        F: FnOnce(Symbol, &str) -> ResolutionError<'_>,
+    fn check_trait_item<F>(
+        &mut self,
+        ident: Ident,
+        kind: &AssocItemKind,
+        ns: Namespace,
+        span: Span,
+        err: F,
+    ) where
+        F: FnOnce(Ident, &str, Option<Symbol>) -> ResolutionError<'_>,
     {
         // If there is a TraitRef in scope for an impl, then the method must be in the
         // trait.
@@ -1420,8 +1431,9 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
                 )
                 .is_err()
             {
+                let candidate = self.find_similarly_named_assoc_item(ident.name, kind);
                 let path = &self.current_trait_ref.as_ref().unwrap().1.path;
-                self.report_error(span, err(ident.name, &path_names_to_string(path)));
+                self.report_error(span, err(ident, &path_names_to_string(path), candidate));
             }
         }
     }
diff --git a/compiler/rustc_resolve/src/late/diagnostics.rs b/compiler/rustc_resolve/src/late/diagnostics.rs
index 84219873d55..e57e7db3285 100644
--- a/compiler/rustc_resolve/src/late/diagnostics.rs
+++ b/compiler/rustc_resolve/src/late/diagnostics.rs
@@ -7,8 +7,8 @@ use crate::{PathResult, PathSource, Segment};
 
 use rustc_ast::visit::FnKind;
 use rustc_ast::{
-    self as ast, Expr, ExprKind, GenericParam, GenericParamKind, Item, ItemKind, NodeId, Path, Ty,
-    TyKind,
+    self as ast, AssocItemKind, Expr, ExprKind, GenericParam, GenericParamKind, Item, ItemKind,
+    NodeId, Path, Ty, TyKind,
 };
 use rustc_ast_pretty::pprust::path_segment_to_string;
 use rustc_data_structures::fx::FxHashSet;
@@ -1150,6 +1150,40 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
         true
     }
 
+    /// Given the target `ident` and `kind`, search for the similarly named associated item
+    /// in `self.current_trait_ref`.
+    crate fn find_similarly_named_assoc_item(
+        &mut self,
+        ident: Symbol,
+        kind: &AssocItemKind,
+    ) -> Option<Symbol> {
+        let module = if let Some((module, _)) = self.current_trait_ref {
+            module
+        } else {
+            return None;
+        };
+        if ident == kw::Underscore {
+            // We do nothing for `_`.
+            return None;
+        }
+
+        let resolutions = self.r.resolutions(module);
+        let targets = resolutions
+            .borrow()
+            .iter()
+            .filter_map(|(key, res)| res.borrow().binding.map(|binding| (key, binding.res())))
+            .filter(|(_, res)| match (kind, res) {
+                (AssocItemKind::Const(..), Res::Def(DefKind::AssocConst, _)) => true,
+                (AssocItemKind::Fn(_), Res::Def(DefKind::AssocFn, _)) => true,
+                (AssocItemKind::TyAlias(..), Res::Def(DefKind::AssocTy, _)) => true,
+                _ => false,
+            })
+            .map(|(key, _)| key.ident.name)
+            .collect::<Vec<_>>();
+
+        find_best_match_for_name(&targets, ident, None)
+    }
+
     fn lookup_assoc_candidate<FilterFn>(
         &mut self,
         ident: Ident,
diff --git a/compiler/rustc_resolve/src/late/lifetimes.rs b/compiler/rustc_resolve/src/late/lifetimes.rs
index 84e7c68713f..eb6f302a11d 100644
--- a/compiler/rustc_resolve/src/late/lifetimes.rs
+++ b/compiler/rustc_resolve/src/late/lifetimes.rs
@@ -2740,6 +2740,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
         for input in inputs {
             gather.visit_ty(input);
         }
+        trace!(?gather.anon_count);
         let late_bound_vars = self.map.late_bound_vars.entry(hir_id).or_default();
         let named_late_bound_vars = late_bound_vars.len() as u32;
         late_bound_vars.extend(
@@ -3028,6 +3029,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
                 NestedVisitorMap::None
             }
 
+            #[instrument(skip(self), level = "trace")]
             fn visit_ty(&mut self, ty: &hir::Ty<'_>) {
                 // If we enter a `BareFn`, then we enter a *new* binding scope
                 if let hir::TyKind::BareFn(_) = ty.kind {
@@ -3048,6 +3050,7 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
                 intravisit::walk_generic_args(self, path_span, generic_args)
             }
 
+            #[instrument(skip(self), level = "trace")]
             fn visit_lifetime(&mut self, lifetime_ref: &hir::Lifetime) {
                 if lifetime_ref.is_elided() {
                     self.anon_count += 1;
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index 1cbe8f41d92..8ae2d5cdd97 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -20,6 +20,9 @@
 #![recursion_limit = "256"]
 #![allow(rustdoc::private_intra_doc_links)]
 
+#[macro_use]
+extern crate tracing;
+
 pub use rustc_hir::def::{Namespace, PerNS};
 
 use Determinacy::*;
@@ -203,11 +206,11 @@ enum ResolutionError<'a> {
     /// parameter list.
     NameAlreadyUsedInParameterList(Symbol, Span),
     /// Error E0407: method is not a member of trait.
-    MethodNotMemberOfTrait(Symbol, &'a str),
+    MethodNotMemberOfTrait(Ident, &'a str, Option<Symbol>),
     /// Error E0437: type is not a member of trait.
-    TypeNotMemberOfTrait(Symbol, &'a str),
+    TypeNotMemberOfTrait(Ident, &'a str, Option<Symbol>),
     /// Error E0438: const is not a member of trait.
-    ConstNotMemberOfTrait(Symbol, &'a str),
+    ConstNotMemberOfTrait(Ident, &'a str, Option<Symbol>),
     /// Error E0408: variable `{}` is not bound in all patterns.
     VariableNotBoundInPattern(&'a BindingError),
     /// Error E0409: variable `{}` is bound in inconsistent ways within the same match arm.
@@ -1149,7 +1152,7 @@ impl ResolverAstLowering for Resolver<'_> {
         self.legacy_const_generic_args(expr)
     }
 
-    fn get_partial_res(&mut self, id: NodeId) -> Option<PartialRes> {
+    fn get_partial_res(&self, id: NodeId) -> Option<PartialRes> {
         self.partial_res_map.get(&id).cloned()
     }
 
@@ -2966,7 +2969,15 @@ impl<'a> Resolver<'a> {
                 (None, false)
             };
             if !candidates.is_empty() {
-                diagnostics::show_candidates(&mut err, span, &candidates, instead, found_use);
+                diagnostics::show_candidates(
+                    &self.definitions,
+                    self.session,
+                    &mut err,
+                    span,
+                    &candidates,
+                    instead,
+                    found_use,
+                );
             } else if let Some((span, msg, sugg, appl)) = suggestion {
                 err.span_suggestion(span, msg, sugg, appl);
             }
diff --git a/compiler/rustc_resolve/src/macros.rs b/compiler/rustc_resolve/src/macros.rs
index f15cf4bbc3a..4f6e23d8f84 100644
--- a/compiler/rustc_resolve/src/macros.rs
+++ b/compiler/rustc_resolve/src/macros.rs
@@ -1137,7 +1137,7 @@ impl<'a> Resolver<'a> {
         }
         if let Some(depr) = &ext.deprecation {
             let path = pprust::path_to_string(&path);
-            let (message, lint) = stability::deprecation_message(depr, "macro", &path);
+            let (message, lint) = stability::deprecation_message_and_lint(depr, "macro", &path);
             stability::early_report_deprecation(
                 &mut self.lint_buffer,
                 &message,
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index 8110afe75fa..8ecb7a031ad 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -1246,6 +1246,8 @@ options! {
         "enable queries of the dependency graph for regression testing (default: no)"),
     query_stats: bool = (false, parse_bool, [UNTRACKED],
         "print some statistics about the query system (default: no)"),
+    randomize_layout: bool = (false, parse_bool, [TRACKED],
+        "randomize the layout of types (default: no)"),
     relax_elf_relocations: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "whether ELF relocations can be relaxed"),
     relro_level: Option<RelroLevel> = (None, parse_relro_level, [TRACKED],
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index 27215556045..fbcc3bf2c48 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -2,10 +2,9 @@ use crate::cgu_reuse_tracker::CguReuseTracker;
 use crate::code_stats::CodeStats;
 pub use crate::code_stats::{DataTypeKind, FieldInfo, SizeKind, VariantInfo};
 use crate::config::{self, CrateType, OutputType, SwitchWithOptPath};
-use crate::filesearch;
-use crate::lint::{self, LintId};
 use crate::parse::ParseSess;
 use crate::search_paths::{PathKind, SearchPath};
+use crate::{filesearch, lint};
 
 pub use rustc_ast::attr::MarkedAttrs;
 pub use rustc_ast::Attribute;
@@ -41,10 +40,6 @@ use std::str::FromStr;
 use std::sync::Arc;
 use std::time::Duration;
 
-pub trait SessionLintStore: sync::Send + sync::Sync {
-    fn name_to_lint(&self, lint_name: &str) -> LintId;
-}
-
 pub struct OptimizationFuel {
     /// If `-zfuel=crate=n` is specified, initially set to `n`, otherwise `0`.
     remaining: u64,
@@ -153,8 +148,6 @@ pub struct Session {
 
     features: OnceCell<rustc_feature::Features>,
 
-    lint_store: OnceCell<Lrc<dyn SessionLintStore>>,
-
     incr_comp_session: OneThread<RefCell<IncrCompSession>>,
     /// Used for incremental compilation tests. Will only be populated if
     /// `-Zquery-dep-graph` is specified.
@@ -169,9 +162,6 @@ pub struct Session {
     /// Data about code being compiled, gathered during compilation.
     pub code_stats: CodeStats,
 
-    /// If `-zfuel=crate=n` is specified, `Some(crate)`.
-    optimization_fuel_crate: Option<String>,
-
     /// Tracks fuel info if `-zfuel=crate=n` is specified.
     optimization_fuel: Lock<OptimizationFuel>,
 
@@ -591,13 +581,6 @@ impl Session {
         }
     }
 
-    pub fn init_lint_store(&self, lint_store: Lrc<dyn SessionLintStore>) {
-        self.lint_store
-            .set(lint_store)
-            .map_err(|_| ())
-            .expect("`lint_store` was initialized twice");
-    }
-
     /// Calculates the flavor of LTO to use for this compilation.
     pub fn lto(&self) -> config::Lto {
         // If our target has codegen requirements ignore the command line
@@ -896,7 +879,7 @@ impl Session {
     /// This expends fuel if applicable, and records fuel if applicable.
     pub fn consider_optimizing<T: Fn() -> String>(&self, crate_name: &str, msg: T) -> bool {
         let mut ret = true;
-        if let Some(ref c) = self.optimization_fuel_crate {
+        if let Some((ref c, _)) = self.opts.debugging_opts.fuel {
             if c == crate_name {
                 assert_eq!(self.threads(), 1);
                 let mut fuel = self.optimization_fuel.lock();
@@ -1274,7 +1257,6 @@ pub fn build_session(
     let local_crate_source_file =
         local_crate_source_file.map(|path| file_path_mapping.map_prefix(path).0);
 
-    let optimization_fuel_crate = sopts.debugging_opts.fuel.as_ref().map(|i| i.0.clone());
     let optimization_fuel = Lock::new(OptimizationFuel {
         remaining: sopts.debugging_opts.fuel.as_ref().map_or(0, |i| i.1),
         out_of_fuel: false,
@@ -1315,7 +1297,6 @@ pub fn build_session(
         crate_types: OnceCell::new(),
         stable_crate_id: OnceCell::new(),
         features: OnceCell::new(),
-        lint_store: OnceCell::new(),
         incr_comp_session: OneThread::new(RefCell::new(IncrCompSession::NotInitialized)),
         cgu_reuse_tracker,
         prof,
@@ -1326,7 +1307,6 @@ pub fn build_session(
             normalize_projection_ty: AtomicUsize::new(0),
         },
         code_stats: Default::default(),
-        optimization_fuel_crate,
         optimization_fuel,
         print_fuel,
         jobserver: jobserver::client(),
diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs
index d18e5823cb8..5276da1ba5a 100644
--- a/compiler/rustc_target/src/spec/mod.rs
+++ b/compiler/rustc_target/src/spec/mod.rs
@@ -288,6 +288,7 @@ impl ToJson for MergeFunctions {
 pub enum RelocModel {
     Static,
     Pic,
+    Pie,
     DynamicNoPic,
     Ropi,
     Rwpi,
@@ -301,6 +302,7 @@ impl FromStr for RelocModel {
         Ok(match s {
             "static" => RelocModel::Static,
             "pic" => RelocModel::Pic,
+            "pie" => RelocModel::Pie,
             "dynamic-no-pic" => RelocModel::DynamicNoPic,
             "ropi" => RelocModel::Ropi,
             "rwpi" => RelocModel::Rwpi,
@@ -315,6 +317,7 @@ impl ToJson for RelocModel {
         match *self {
             RelocModel::Static => "static",
             RelocModel::Pic => "pic",
+            RelocModel::Pie => "pie",
             RelocModel::DynamicNoPic => "dynamic-no-pic",
             RelocModel::Ropi => "ropi",
             RelocModel::Rwpi => "rwpi",
diff --git a/compiler/rustc_trait_selection/src/autoderef.rs b/compiler/rustc_trait_selection/src/autoderef.rs
index a89796f172c..53afe4ca068 100644
--- a/compiler/rustc_trait_selection/src/autoderef.rs
+++ b/compiler/rustc_trait_selection/src/autoderef.rs
@@ -5,7 +5,7 @@ use rustc_hir as hir;
 use rustc_infer::infer::InferCtxt;
 use rustc_middle::ty::{self, TraitRef, Ty, TyCtxt, WithConstness};
 use rustc_middle::ty::{ToPredicate, TypeFoldable};
-use rustc_session::DiagnosticMessageId;
+use rustc_session::{DiagnosticMessageId, Limit};
 use rustc_span::def_id::LOCAL_CRATE;
 use rustc_span::Span;
 
@@ -217,7 +217,10 @@ impl<'a, 'tcx> Autoderef<'a, 'tcx> {
 
 pub fn report_autoderef_recursion_limit_error<'tcx>(tcx: TyCtxt<'tcx>, span: Span, ty: Ty<'tcx>) {
     // We've reached the recursion limit, error gracefully.
-    let suggested_limit = tcx.recursion_limit() * 2;
+    let suggested_limit = match tcx.recursion_limit() {
+        Limit(0) => Limit(2),
+        limit => limit * 2,
+    };
     let msg = format!("reached the recursion limit while auto-dereferencing `{:?}`", ty);
     let error_id = (DiagnosticMessageId::ErrorId(55), Some(span), msg);
     let fresh = tcx.sess.one_time_diagnostics.borrow_mut().insert(error_id);
@@ -231,7 +234,8 @@ pub fn report_autoderef_recursion_limit_error<'tcx>(tcx: TyCtxt<'tcx>, span: Spa
         )
         .span_label(span, "deref recursion limit reached")
         .help(&format!(
-            "consider adding a `#![recursion_limit=\"{}\"]` attribute to your crate (`{}`)",
+            "consider increasing the recursion limit by adding a \
+             `#![recursion_limit = \"{}\"]` attribute to your crate (`{}`)",
             suggested_limit,
             tcx.crate_name(LOCAL_CRATE),
         ))
diff --git a/compiler/rustc_trait_selection/src/opaque_types.rs b/compiler/rustc_trait_selection/src/opaque_types.rs
index 028f6e89f18..c2205462680 100644
--- a/compiler/rustc_trait_selection/src/opaque_types.rs
+++ b/compiler/rustc_trait_selection/src/opaque_types.rs
@@ -517,6 +517,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
         debug!(?id_substs);
         let map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>> =
             substs.iter().enumerate().map(|(index, subst)| (subst, id_substs[index])).collect();
+        debug!("map = {:#?}", map);
 
         // Convert the type from the function into a type valid outside
         // the function, by replacing invalid regions with 'static,
@@ -672,6 +673,7 @@ impl TypeFolder<'tcx> for ReverseMapper<'tcx> {
         self.tcx
     }
 
+    #[instrument(skip(self), level = "debug")]
     fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
         match r {
             // Ignore bound regions and `'static` regions that appear in the
@@ -1098,18 +1100,17 @@ fn may_define_opaque_type(tcx: TyCtxt<'_>, def_id: LocalDefId, opaque_hir_id: hi
 ///
 /// Requires that trait definitions have been processed so that we can
 /// elaborate predicates and walk supertraits.
+#[instrument(skip(tcx, predicates), level = "debug")]
 crate fn required_region_bounds(
     tcx: TyCtxt<'tcx>,
     erased_self_ty: Ty<'tcx>,
     predicates: impl Iterator<Item = ty::Predicate<'tcx>>,
 ) -> Vec<ty::Region<'tcx>> {
-    debug!("required_region_bounds(erased_self_ty={:?})", erased_self_ty);
-
     assert!(!erased_self_ty.has_escaping_bound_vars());
 
     traits::elaborate_predicates(tcx, predicates)
         .filter_map(|obligation| {
-            debug!("required_region_bounds(obligation={:?})", obligation);
+            debug!(?obligation);
             match obligation.predicate.kind().skip_binder() {
                 ty::PredicateKind::Projection(..)
                 | ty::PredicateKind::Trait(..)
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
index e435154d931..b751918463b 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
@@ -1195,13 +1195,13 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> {
         false
     }
 
+    #[instrument(skip(self), level = "debug")]
     fn report_fulfillment_error(
         &self,
         error: &FulfillmentError<'tcx>,
         body_id: Option<hir::BodyId>,
         fallback_has_occurred: bool,
     ) {
-        debug!("report_fulfillment_error({:?})", error);
         match error.code {
             FulfillmentErrorCode::CodeSelectionError(ref selection_error) => {
                 self.report_selection_error(
@@ -1528,6 +1528,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> {
         )
     }
 
+    #[instrument(skip(self), level = "debug")]
     fn maybe_report_ambiguity(
         &self,
         obligation: &PredicateObligation<'tcx>,
@@ -1542,8 +1543,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> {
         let span = obligation.cause.span;
 
         debug!(
-            "maybe_report_ambiguity(predicate={:?}, obligation={:?} body_id={:?}, code={:?})",
-            predicate, obligation, body_id, obligation.cause.code,
+            ?predicate, ?obligation.cause.code,
         );
 
         // Ambiguity errors are often caused as fallout from earlier
@@ -1556,7 +1556,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> {
         let mut err = match bound_predicate.skip_binder() {
             ty::PredicateKind::Trait(data) => {
                 let trait_ref = bound_predicate.rebind(data.trait_ref);
-                debug!("trait_ref {:?}", trait_ref);
+                debug!(?trait_ref);
 
                 if predicate.references_error() {
                     return;
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
index 2a51e014713..325126483b9 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -22,6 +22,7 @@ use rustc_middle::ty::{
     Infer, InferTy, ToPredicate, Ty, TyCtxt, TypeFoldable, WithConstness,
 };
 use rustc_middle::ty::{TypeAndMut, TypeckResults};
+use rustc_session::Limit;
 use rustc_span::def_id::LOCAL_CRATE;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{BytePos, DesugaringKind, ExpnKind, ForLoopLoc, MultiSpan, Span, DUMMY_SP};
@@ -2426,10 +2427,13 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
     }
 
     fn suggest_new_overflow_limit(&self, err: &mut DiagnosticBuilder<'_>) {
-        let current_limit = self.tcx.recursion_limit();
-        let suggested_limit = current_limit * 2;
+        let suggested_limit = match self.tcx.recursion_limit() {
+            Limit(0) => Limit(2),
+            limit => limit * 2,
+        };
         err.help(&format!(
-            "consider adding a `#![recursion_limit=\"{}\"]` attribute to your crate (`{}`)",
+            "consider increasing the recursion limit by adding a \
+             `#![recursion_limit = \"{}\"]` attribute to your crate (`{}`)",
             suggested_limit,
             self.tcx.crate_name(LOCAL_CRATE),
         ));
diff --git a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
index 6d64dc8254b..397f1da75ef 100644
--- a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
@@ -220,6 +220,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         self.filter_impls(candidates.pop().unwrap().candidate, stack.obligation)
     }
 
+    #[instrument(skip(self, stack), level = "debug")]
     pub(super) fn assemble_candidates<'o>(
         &mut self,
         stack: &TraitObligationStack<'o, 'tcx>,
diff --git a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
index 9e1211336a4..8554723740f 100644
--- a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
@@ -601,12 +601,11 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         Ok(ImplSourceGeneratorData { generator_def_id, substs, nested: obligations })
     }
 
+    #[instrument(skip(self), level = "debug")]
     fn confirm_closure_candidate(
         &mut self,
         obligation: &TraitObligation<'tcx>,
     ) -> Result<ImplSourceClosureData<'tcx, PredicateObligation<'tcx>>, SelectionError<'tcx>> {
-        debug!(?obligation, "confirm_closure_candidate");
-
         let kind = self
             .tcx()
             .fn_trait_kind_from_lang_item(obligation.predicate.def_id())
@@ -680,6 +679,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     /// because these output type parameters should not affect the
     /// selection of the impl. Therefore, if there is a mismatch, we
     /// report an error to the user.
+    #[instrument(skip(self), level = "trace")]
     fn confirm_poly_trait_refs(
         &mut self,
         obligation_cause: ObligationCause<'tcx>,
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index 50d6f82ae18..af0c7c8f956 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -451,6 +451,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     /// Evaluates the predicates in `predicates` recursively. Note that
     /// this applies projections in the predicates, and therefore
     /// is run within an inference probe.
+    #[instrument(skip(self, stack), level = "debug")]
     fn evaluate_predicates_recursively<'o, I>(
         &mut self,
         stack: TraitObligationStackList<'o, 'tcx>,
@@ -460,7 +461,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         I: IntoIterator<Item = PredicateObligation<'tcx>> + std::fmt::Debug,
     {
         let mut result = EvaluatedToOk;
-        debug!(?predicates, "evaluate_predicates_recursively");
         for obligation in predicates {
             let eval = self.evaluate_predicate_recursively(stack, obligation.clone())?;
             if let EvaluatedToErr = eval {
@@ -683,13 +683,12 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         result
     }
 
+    #[instrument(skip(self, previous_stack), level = "debug")]
     fn evaluate_trait_predicate_recursively<'o>(
         &mut self,
         previous_stack: TraitObligationStackList<'o, 'tcx>,
         mut obligation: TraitObligation<'tcx>,
     ) -> Result<EvaluationResult, OverflowError> {
-        debug!(?obligation, "evaluate_trait_predicate_recursively");
-
         if !self.intercrate
             && obligation.is_global(self.tcx())
             && obligation
@@ -701,7 +700,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             // If a param env has no global bounds, global obligations do not
             // depend on its particular value in order to work, so we can clear
             // out the param env and get better caching.
-            debug!("evaluate_trait_predicate_recursively - in global");
+            debug!("in global");
             obligation.param_env = obligation.param_env.without_caller_bounds();
         }
 
@@ -753,7 +752,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         } else {
             debug!(?result, "PROVISIONAL");
             debug!(
-                "evaluate_trait_predicate_recursively: caching provisionally because {:?} \
+                "caching provisionally because {:?} \
                  is a cycle participant (at depth {}, reached depth {})",
                 fresh_trait_ref, stack.depth, reached_depth,
             );
@@ -2124,13 +2123,12 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
     /// Returns `Ok` if `poly_trait_ref` being true implies that the
     /// obligation is satisfied.
+    #[instrument(skip(self), level = "debug")]
     fn match_poly_trait_ref(
         &mut self,
         obligation: &TraitObligation<'tcx>,
         poly_trait_ref: ty::PolyTraitRef<'tcx>,
     ) -> Result<Vec<PredicateObligation<'tcx>>, ()> {
-        debug!(?obligation, ?poly_trait_ref, "match_poly_trait_ref");
-
         self.infcx
             .at(&obligation.cause, obligation.param_env)
             .sup(obligation.predicate.to_poly_trait_ref(), poly_trait_ref)
@@ -2174,12 +2172,12 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         }
     }
 
+    #[instrument(skip(self), level = "debug")]
     fn closure_trait_ref_unnormalized(
         &mut self,
         obligation: &TraitObligation<'tcx>,
         substs: SubstsRef<'tcx>,
     ) -> ty::PolyTraitRef<'tcx> {
-        debug!(?obligation, ?substs, "closure_trait_ref_unnormalized");
         let closure_sig = substs.as_closure().sig();
 
         debug!(?closure_sig);
diff --git a/compiler/rustc_typeck/src/astconv/generics.rs b/compiler/rustc_typeck/src/astconv/generics.rs
index fd0544a47bb..456d3fe7b2f 100644
--- a/compiler/rustc_typeck/src/astconv/generics.rs
+++ b/compiler/rustc_typeck/src/astconv/generics.rs
@@ -441,6 +441,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
 
     /// Checks that the correct number of generic arguments have been provided.
     /// This is used both for datatypes and function calls.
+    #[instrument(skip(tcx, gen_pos), level = "debug")]
     pub(crate) fn check_generic_arg_count(
         tcx: TyCtxt<'_>,
         span: Span,
@@ -452,11 +453,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         has_self: bool,
         infer_args: bool,
     ) -> GenericArgCountResult {
-        debug!(
-            "check_generic_arg_count(span: {:?}, def_id: {:?}, seg: {:?}, gen_params: {:?}, gen_args: {:?})",
-            span, def_id, seg, gen_params, gen_args
-        );
-
         let default_counts = gen_params.own_defaults();
         let param_counts = gen_params.own_counts();
 
@@ -556,9 +552,12 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         let mut check_types_and_consts =
             |expected_min, expected_max, provided, params_offset, args_offset| {
                 debug!(
-                    "check_types_and_consts(expected_min: {:?}, expected_max: {:?}, \
-                        provided: {:?}, params_offset: {:?}, args_offset: {:?}",
-                    expected_min, expected_max, provided, params_offset, args_offset
+                    ?expected_min,
+                    ?expected_max,
+                    ?provided,
+                    ?params_offset,
+                    ?args_offset,
+                    "check_types_and_consts"
                 );
                 if (expected_min..=expected_max).contains(&provided) {
                     return true;
@@ -589,7 +588,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                     }
                 };
 
-                debug!("gen_args_info: {:?}", gen_args_info);
+                debug!(?gen_args_info);
 
                 WrongNumberOfGenericArgs::new(
                     tcx,
@@ -601,7 +600,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                     def_id,
                 )
                 .diagnostic()
-                .emit();
+                .emit_unless(gen_args.has_err());
 
                 false
             };
@@ -614,8 +613,8 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                     - default_counts.types
                     - default_counts.consts
             };
-            debug!("expected_min: {:?}", expected_min);
-            debug!("arg_counts.lifetimes: {:?}", gen_args.num_lifetime_params());
+            debug!(?expected_min);
+            debug!(arg_counts.lifetimes=?gen_args.num_lifetime_params());
 
             check_types_and_consts(
                 expected_min,
diff --git a/compiler/rustc_typeck/src/check/callee.rs b/compiler/rustc_typeck/src/check/callee.rs
index e007d971bb0..4ffb061f7b4 100644
--- a/compiler/rustc_typeck/src/check/callee.rs
+++ b/compiler/rustc_typeck/src/check/callee.rs
@@ -356,6 +356,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     }
                 }
 
+                let callee_ty = self.resolve_vars_if_possible(callee_ty);
                 let mut err = type_error_struct!(
                     self.tcx.sess,
                     callee_expr.span,
diff --git a/compiler/rustc_typeck/src/check/check.rs b/compiler/rustc_typeck/src/check/check.rs
index 9f0ed0cd18d..c1d14413554 100644
--- a/compiler/rustc_typeck/src/check/check.rs
+++ b/compiler/rustc_typeck/src/check/check.rs
@@ -70,6 +70,7 @@ pub(super) fn check_abi(tcx: TyCtxt<'_>, hir_id: hir::HirId, span: Span, abi: Ab
 ///
 /// * ...
 /// * inherited: other fields inherited from the enclosing fn (if any)
+#[instrument(skip(inherited, body), level = "debug")]
 pub(super) fn check_fn<'a, 'tcx>(
     inherited: &'a Inherited<'a, 'tcx>,
     param_env: ty::ParamEnv<'tcx>,
@@ -82,8 +83,6 @@ pub(super) fn check_fn<'a, 'tcx>(
 ) -> (FnCtxt<'a, 'tcx>, Option<GeneratorTypes<'tcx>>) {
     let mut fn_sig = fn_sig;
 
-    debug!("check_fn(sig={:?}, fn_id={}, param_env={:?})", fn_sig, fn_id, param_env);
-
     // Create the function context. This is either derived from scratch or,
     // in the case of closures, based on the outer context.
     let mut fcx = FnCtxt::new(inherited, param_env, body.value.hir_id);
diff --git a/compiler/rustc_typeck/src/check/closure.rs b/compiler/rustc_typeck/src/check/closure.rs
index 65ba1c08b62..410ac24b1f1 100644
--- a/compiler/rustc_typeck/src/check/closure.rs
+++ b/compiler/rustc_typeck/src/check/closure.rs
@@ -33,6 +33,7 @@ struct ClosureSignatures<'tcx> {
 }
 
 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
+    #[instrument(skip(self, expr, _capture, decl, body_id), level = "debug")]
     pub fn check_expr_closure(
         &self,
         expr: &hir::Expr<'_>,
@@ -42,7 +43,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         gen: Option<hir::Movability>,
         expected: Expectation<'tcx>,
     ) -> Ty<'tcx> {
-        debug!("check_expr_closure(expr={:?},expected={:?})", expr, expected);
+        trace!("decl = {:#?}", decl);
+        trace!("expr = {:#?}", expr);
 
         // It's always helpful for inference if we know the kind of
         // closure sooner rather than later, so first examine the expected
@@ -55,6 +57,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         self.check_closure(expr, expected_kind, decl, body, gen, expected_sig)
     }
 
+    #[instrument(skip(self, expr, body, decl), level = "debug")]
     fn check_closure(
         &self,
         expr: &hir::Expr<'_>,
@@ -64,14 +67,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         gen: Option<hir::Movability>,
         expected_sig: Option<ExpectedSig<'tcx>>,
     ) -> Ty<'tcx> {
-        debug!("check_closure(opt_kind={:?}, expected_sig={:?})", opt_kind, expected_sig);
-
+        trace!("decl = {:#?}", decl);
         let expr_def_id = self.tcx.hir().local_def_id(expr.hir_id);
+        debug!(?expr_def_id);
 
         let ClosureSignatures { bound_sig, liberated_sig } =
             self.sig_of_closure(expr.hir_id, expr_def_id.to_def_id(), decl, body, expected_sig);
 
-        debug!("check_closure: ty_of_closure returns {:?}", liberated_sig);
+        debug!(?bound_sig, ?liberated_sig);
 
         let return_type_pre_known = !liberated_sig.output().is_ty_infer();
 
@@ -130,10 +133,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             )
         });
 
-        debug!(
-            "check_closure: expr_def_id={:?}, sig={:?}, opt_kind={:?}",
-            expr_def_id, sig, opt_kind
-        );
+        debug!(?sig, ?opt_kind);
 
         let closure_kind_ty = match opt_kind {
             Some(kind) => kind.to_ty(self.tcx),
@@ -159,19 +159,18 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         let closure_type = self.tcx.mk_closure(expr_def_id.to_def_id(), closure_substs.substs);
 
-        debug!("check_closure: expr.hir_id={:?} closure_type={:?}", expr.hir_id, closure_type);
+        debug!(?expr.hir_id, ?closure_type);
 
         closure_type
     }
 
     /// Given the expected type, figures out what it can about this closure we
     /// are about to type check:
+    #[instrument(skip(self), level = "debug")]
     fn deduce_expectations_from_expected_type(
         &self,
         expected_ty: Ty<'tcx>,
     ) -> (Option<ExpectedSig<'tcx>>, Option<ty::ClosureKind>) {
-        debug!("deduce_expectations_from_expected_type(expected_ty={:?})", expected_ty);
-
         match *expected_ty.kind() {
             ty::Dynamic(ref object_type, ..) => {
                 let sig = object_type.projection_bounds().find_map(|pb| {
@@ -314,6 +313,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
     /// If there is no expected signature, then we will convert the
     /// types that the user gave into a signature.
+    #[instrument(skip(self, hir_id, expr_def_id, decl, body), level = "debug")]
     fn sig_of_closure_no_expectation(
         &self,
         hir_id: hir::HirId,
@@ -321,8 +321,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         decl: &hir::FnDecl<'_>,
         body: &hir::Body<'_>,
     ) -> ClosureSignatures<'tcx> {
-        debug!("sig_of_closure_no_expectation()");
-
         let bound_sig = self.supplied_sig_of_closure(hir_id, expr_def_id, decl, body);
 
         self.closure_sigs(expr_def_id, body, bound_sig)
@@ -375,6 +373,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     /// - `expected_sig`: the expected signature (if any). Note that
     ///   this is missing a binder: that is, there may be late-bound
     ///   regions with depth 1, which are bound then by the closure.
+    #[instrument(skip(self, hir_id, expr_def_id, decl, body), level = "debug")]
     fn sig_of_closure_with_expectation(
         &self,
         hir_id: hir::HirId,
@@ -383,8 +382,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         body: &hir::Body<'_>,
         expected_sig: ExpectedSig<'tcx>,
     ) -> ClosureSignatures<'tcx> {
-        debug!("sig_of_closure_with_expectation(expected_sig={:?})", expected_sig);
-
         // Watch out for some surprises and just ignore the
         // expectation if things don't see to match up with what we
         // expect.
@@ -553,6 +550,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     /// types that the user gave into a signature.
     ///
     /// Also, record this closure signature for later.
+    #[instrument(skip(self, decl, body), level = "debug")]
     fn supplied_sig_of_closure(
         &self,
         hir_id: hir::HirId,
@@ -562,10 +560,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     ) -> ty::PolyFnSig<'tcx> {
         let astconv: &dyn AstConv<'_> = self;
 
-        debug!(
-            "supplied_sig_of_closure(decl={:?}, body.generator_kind={:?})",
-            decl, body.generator_kind,
-        );
+        trace!("decl = {:#?}", decl);
+        debug!(?body.generator_kind);
 
         let bound_vars = self.tcx.late_bound_vars(hir_id);
 
@@ -578,7 +574,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 // we expect the return type of the block to match that of the enclosing
                 // function.
                 Some(hir::GeneratorKind::Async(hir::AsyncGeneratorKind::Fn)) => {
-                    debug!("supplied_sig_of_closure: closure is async fn body");
+                    debug!("closure is async fn body");
                     self.deduce_future_output_from_obligations(expr_def_id).unwrap_or_else(|| {
                         // AFAIK, deducing the future output
                         // always succeeds *except* in error cases
@@ -606,7 +602,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             bound_vars,
         );
 
-        debug!("supplied_sig_of_closure: result={:?}", result);
+        debug!(?result);
 
         let c_result = self.inh.infcx.canonicalize_response(result);
         self.typeck_results.borrow_mut().user_provided_sigs.insert(expr_def_id, c_result);
diff --git a/compiler/rustc_typeck/src/check/coercion.rs b/compiler/rustc_typeck/src/check/coercion.rs
index ef18c1e7779..79763942d05 100644
--- a/compiler/rustc_typeck/src/check/coercion.rs
+++ b/compiler/rustc_typeck/src/check/coercion.rs
@@ -482,12 +482,11 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
     // &[T; n] or &mut [T; n] -> &[T]
     // or &mut [T; n] -> &mut [T]
     // or &Concrete -> &Trait, etc.
+    #[instrument(skip(self), level = "debug")]
     fn coerce_unsized(&self, mut source: Ty<'tcx>, mut target: Ty<'tcx>) -> CoerceResult<'tcx> {
-        debug!("coerce_unsized(source={:?}, target={:?})", source, target);
-
         source = self.shallow_resolve(source);
         target = self.shallow_resolve(target);
-        debug!("coerce_unsized: resolved source={:?} target={:?}", source, target);
+        debug!(?source, ?target);
 
         // These 'if' statements require some explanation.
         // The `CoerceUnsized` trait is special - it is only
diff --git a/compiler/rustc_typeck/src/check/demand.rs b/compiler/rustc_typeck/src/check/demand.rs
index 722b110ed61..dcfbaff7ec7 100644
--- a/compiler/rustc_typeck/src/check/demand.rs
+++ b/compiler/rustc_typeck/src/check/demand.rs
@@ -59,6 +59,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         self.demand_suptype_with_origin(&self.misc(sp), expected, actual)
     }
 
+    #[instrument(skip(self), level = "debug")]
     pub fn demand_suptype_with_origin(
         &self,
         cause: &ObligationCause<'tcx>,
diff --git a/compiler/rustc_typeck/src/check/expr.rs b/compiler/rustc_typeck/src/check/expr.rs
index 8a69e0a737d..09a55937cc5 100644
--- a/compiler/rustc_typeck/src/check/expr.rs
+++ b/compiler/rustc_typeck/src/check/expr.rs
@@ -156,7 +156,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     /// Note that inspecting a type's structure *directly* may expose the fact
     /// that there are actually multiple representations for `Error`, so avoid
     /// that when err needs to be handled differently.
-    #[instrument(skip(self), level = "debug")]
+    #[instrument(skip(self, expr), level = "debug")]
     pub(super) fn check_expr_with_expectation(
         &self,
         expr: &'tcx hir::Expr<'tcx>,
@@ -254,12 +254,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         ty
     }
 
+    #[instrument(skip(self, expr), level = "debug")]
     fn check_expr_kind(
         &self,
         expr: &'tcx hir::Expr<'tcx>,
         expected: Expectation<'tcx>,
     ) -> Ty<'tcx> {
-        debug!("check_expr_kind(expected={:?}, expr={:?})", expected, expr);
+        trace!("expr={:#?}", expr);
 
         let tcx = self.tcx;
         match expr.kind {
@@ -2136,7 +2137,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             idx_t
         } else {
             let base_t = self.structurally_resolved_type(base.span, base_t);
-            match self.lookup_indexing(expr, base, base_t, idx_t) {
+            match self.lookup_indexing(expr, base, base_t, idx, idx_t) {
                 Some((index_ty, element_ty)) => {
                     // two-phase not needed because index_ty is never mutable
                     self.demand_coerce(idx, idx_t, index_ty, None, AllowTwoPhase::No);
diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs b/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs
index 553f5ed8a0c..7b9629e534b 100644
--- a/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs
+++ b/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs
@@ -87,23 +87,22 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         self.resolve_vars_with_obligations_and_mutate_fulfillment(ty, |_| {})
     }
 
+    #[instrument(skip(self, mutate_fulfillment_errors), level = "debug")]
     pub(in super::super) fn resolve_vars_with_obligations_and_mutate_fulfillment(
         &self,
         mut ty: Ty<'tcx>,
         mutate_fulfillment_errors: impl Fn(&mut Vec<traits::FulfillmentError<'tcx>>),
     ) -> Ty<'tcx> {
-        debug!("resolve_vars_with_obligations(ty={:?})", ty);
-
         // No Infer()? Nothing needs doing.
         if !ty.has_infer_types_or_consts() {
-            debug!("resolve_vars_with_obligations: ty={:?}", ty);
+            debug!("no inference var, nothing needs doing");
             return ty;
         }
 
         // If `ty` is a type variable, see whether we already know what it is.
         ty = self.resolve_vars_if_possible(ty);
         if !ty.has_infer_types_or_consts() {
-            debug!("resolve_vars_with_obligations: ty={:?}", ty);
+            debug!(?ty);
             return ty;
         }
 
@@ -114,7 +113,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         self.select_obligations_where_possible(false, mutate_fulfillment_errors);
         ty = self.resolve_vars_if_possible(ty);
 
-        debug!("resolve_vars_with_obligations: ty={:?}", ty);
+        debug!(?ty);
         ty
     }
 
@@ -230,6 +229,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     /// This should be invoked **before any unifications have
     /// occurred**, so that annotations like `Vec<_>` are preserved
     /// properly.
+    #[instrument(skip(self), level = "debug")]
     pub fn write_user_type_annotation_from_substs(
         &self,
         hir_id: hir::HirId,
@@ -237,37 +237,25 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         substs: SubstsRef<'tcx>,
         user_self_ty: Option<UserSelfTy<'tcx>>,
     ) {
-        debug!(
-            "write_user_type_annotation_from_substs: hir_id={:?} def_id={:?} substs={:?} \
-             user_self_ty={:?} in fcx {}",
-            hir_id,
-            def_id,
-            substs,
-            user_self_ty,
-            self.tag(),
-        );
+        debug!("fcx {}", self.tag());
 
         if self.can_contain_user_lifetime_bounds((substs, user_self_ty)) {
             let canonicalized = self.infcx.canonicalize_user_type_annotation(UserType::TypeOf(
                 def_id,
                 UserSubsts { substs, user_self_ty },
             ));
-            debug!("write_user_type_annotation_from_substs: canonicalized={:?}", canonicalized);
+            debug!(?canonicalized);
             self.write_user_type_annotation(hir_id, canonicalized);
         }
     }
 
+    #[instrument(skip(self), level = "debug")]
     pub fn write_user_type_annotation(
         &self,
         hir_id: hir::HirId,
         canonical_user_type_annotation: CanonicalUserType<'tcx>,
     ) {
-        debug!(
-            "write_user_type_annotation: hir_id={:?} canonical_user_type_annotation={:?} tag={}",
-            hir_id,
-            canonical_user_type_annotation,
-            self.tag(),
-        );
+        debug!("fcx {}", self.tag());
 
         if !canonical_user_type_annotation.is_identity() {
             self.typeck_results
@@ -275,12 +263,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 .user_provided_types_mut()
                 .insert(hir_id, canonical_user_type_annotation);
         } else {
-            debug!("write_user_type_annotation: skipping identity substs");
+            debug!("skipping identity substs");
         }
     }
 
+    #[instrument(skip(self, expr), level = "debug")]
     pub fn apply_adjustments(&self, expr: &hir::Expr<'_>, adj: Vec<Adjustment<'tcx>>) {
-        debug!("apply_adjustments(expr={:?}, adj={:?})", expr, adj);
+        debug!("expr = {:#?}", expr);
 
         if adj.is_empty() {
             return;
@@ -652,8 +641,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
     }
 
+    #[instrument(skip(self), level = "debug")]
     pub(in super::super) fn select_all_obligations_or_error(&self) {
-        debug!("select_all_obligations_or_error");
         if let Err(errors) = self
             .fulfillment_cx
             .borrow_mut()
@@ -694,16 +683,15 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         ret_ty.builtin_deref(true).unwrap()
     }
 
+    #[instrument(skip(self), level = "debug")]
     fn self_type_matches_expected_vid(
         &self,
         trait_ref: ty::PolyTraitRef<'tcx>,
         expected_vid: ty::TyVid,
     ) -> bool {
         let self_ty = self.shallow_resolve(trait_ref.skip_binder().self_ty());
-        debug!(
-            "self_type_matches_expected_vid(trait_ref={:?}, self_ty={:?}, expected_vid={:?})",
-            trait_ref, self_ty, expected_vid
-        );
+        debug!(?self_ty);
+
         match *self_ty.kind() {
             ty::Infer(ty::TyVar(found_vid)) => {
                 // FIXME: consider using `sub_root_var` here so we
@@ -716,6 +704,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
     }
 
+    #[instrument(skip(self), level = "debug")]
     pub(in super::super) fn obligations_for_self_ty<'b>(
         &'b self,
         self_ty: ty::TyVid,
@@ -725,12 +714,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // FIXME: consider using `sub_root_var` here so we
         // can see through subtyping.
         let ty_var_root = self.root_var(self_ty);
-        debug!(
-            "obligations_for_self_ty: self_ty={:?} ty_var_root={:?} pending_obligations={:?}",
-            self_ty,
-            ty_var_root,
-            self.fulfillment_cx.borrow().pending_obligations()
-        );
+        trace!("pending_obligations = {:#?}", self.fulfillment_cx.borrow().pending_obligations());
 
         self.fulfillment_cx
             .borrow()
@@ -780,6 +764,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
     /// Unifies the output type with the expected type early, for more coercions
     /// and forward type information on the input expressions.
+    #[instrument(skip(self, call_span), level = "debug")]
     pub(in super::super) fn expected_inputs_for_expected_output(
         &self,
         call_span: Span,
@@ -826,10 +811,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 Ok(formal_args.iter().map(|&ty| self.resolve_vars_if_possible(ty)).collect())
             })
             .unwrap_or_default();
-        debug!(
-            "expected_inputs_for_expected_output(formal={:?} -> {:?}, expected={:?} -> {:?})",
-            formal_args, formal_ret, expect_args, expected_ret
-        );
+        debug!(?formal_args, ?formal_ret, ?expect_args, ?expected_ret);
         expect_args
     }
 
@@ -1195,6 +1177,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
     // Instantiates the given path, which must refer to an item with the given
     // number of type parameters and type.
+    #[instrument(skip(self, span), level = "debug")]
     pub fn instantiate_value_path(
         &self,
         segments: &[hir::PathSegment<'_>],
@@ -1203,11 +1186,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         span: Span,
         hir_id: hir::HirId,
     ) -> (Ty<'tcx>, Res) {
-        debug!(
-            "instantiate_value_path(segments={:?}, self_ty={:?}, res={:?}, hir_id={})",
-            segments, self_ty, res, hir_id,
-        );
-
         let tcx = self.tcx;
 
         let path_segs = match res {
@@ -1230,7 +1208,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             }
             Res::Def(DefKind::AssocFn | DefKind::AssocConst, def_id) => {
                 let container = tcx.associated_item(def_id).container;
-                debug!("instantiate_value_path: def_id={:?} container={:?}", def_id, container);
+                debug!(?def_id, ?container);
                 match container {
                     ty::TraitContainer(trait_did) => {
                         callee::check_legal_trait_for_method_call(tcx, span, None, span, trait_did)
diff --git a/compiler/rustc_typeck/src/check/method/suggest.rs b/compiler/rustc_typeck/src/check/method/suggest.rs
index 91a164ce063..9c7853dd78d 100644
--- a/compiler/rustc_typeck/src/check/method/suggest.rs
+++ b/compiler/rustc_typeck/src/check/method/suggest.rs
@@ -176,6 +176,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                 sugg_span,
                                 idx,
                                 self.tcx.sess.source_map(),
+                                item.fn_has_self_parameter,
                             );
                         }
                     }
@@ -218,6 +219,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             sugg_span,
                             idx,
                             self.tcx.sess.source_map(),
+                            item.fn_has_self_parameter,
                         );
                     }
                 }
@@ -1736,6 +1738,7 @@ fn print_disambiguation_help(
     span: Span,
     candidate: Option<usize>,
     source_map: &source_map::SourceMap,
+    fn_has_self_parameter: bool,
 ) {
     let mut applicability = Applicability::MachineApplicable;
     let (span, sugg) = if let (ty::AssocKind::Fn, Some(args)) = (kind, args) {
@@ -1754,9 +1757,14 @@ fn print_disambiguation_help(
                 .collect::<Vec<_>>()
                 .join(", "),
         );
+        let trait_name = if !fn_has_self_parameter {
+            format!("<{} as {}>", rcvr_ty, trait_name)
+        } else {
+            trait_name
+        };
         (span, format!("{}::{}{}", trait_name, item_name, args))
     } else {
-        (span.with_hi(item_name.span.lo()), format!("{}::", trait_name))
+        (span.with_hi(item_name.span.lo()), format!("<{} as {}>::", rcvr_ty, trait_name))
     };
     err.span_suggestion_verbose(
         span,
diff --git a/compiler/rustc_typeck/src/check/place_op.rs b/compiler/rustc_typeck/src/check/place_op.rs
index 055072d3a1d..64775d7aba9 100644
--- a/compiler/rustc_typeck/src/check/place_op.rs
+++ b/compiler/rustc_typeck/src/check/place_op.rs
@@ -1,5 +1,7 @@
 use crate::check::method::MethodCallee;
 use crate::check::{has_expected_num_generic_args, FnCtxt, PlaceOp};
+use rustc_ast as ast;
+use rustc_errors::Applicability;
 use rustc_hir as hir;
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc_infer::infer::InferOk;
@@ -47,6 +49,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expr: &hir::Expr<'_>,
         base_expr: &'tcx hir::Expr<'tcx>,
         base_ty: Ty<'tcx>,
+        index_expr: &'tcx hir::Expr<'tcx>,
         idx_ty: Ty<'tcx>,
     ) -> Option<(/*index type*/ Ty<'tcx>, /*element type*/ Ty<'tcx>)> {
         // FIXME(#18741) -- this is almost but not quite the same as the
@@ -56,12 +59,42 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let mut autoderef = self.autoderef(base_expr.span, base_ty);
         let mut result = None;
         while result.is_none() && autoderef.next().is_some() {
-            result = self.try_index_step(expr, base_expr, &autoderef, idx_ty);
+            result = self.try_index_step(expr, base_expr, &autoderef, idx_ty, index_expr);
         }
         self.register_predicates(autoderef.into_obligations());
         result
     }
 
+    fn negative_index(
+        &self,
+        ty: Ty<'tcx>,
+        span: Span,
+        base_expr: &hir::Expr<'_>,
+    ) -> Option<(Ty<'tcx>, Ty<'tcx>)> {
+        let ty = self.resolve_vars_if_possible(ty);
+        let mut err = self.tcx.sess.struct_span_err(
+            span,
+            &format!("negative integers cannot be used to index on a `{}`", ty),
+        );
+        err.span_label(span, &format!("cannot use a negative integer for indexing on `{}`", ty));
+        if let (hir::ExprKind::Path(..), Ok(snippet)) =
+            (&base_expr.kind, self.tcx.sess.source_map().span_to_snippet(base_expr.span))
+        {
+            // `foo[-1]` to `foo[foo.len() - 1]`
+            err.span_suggestion_verbose(
+                span.shrink_to_lo(),
+                &format!(
+                    "to access an element starting from the end of the `{}`, compute the index",
+                    ty,
+                ),
+                format!("{}.len() ", snippet),
+                Applicability::MachineApplicable,
+            );
+        }
+        err.emit();
+        Some((self.tcx.ty_error(), self.tcx.ty_error()))
+    }
+
     /// To type-check `base_expr[index_expr]`, we progressively autoderef
     /// (and otherwise adjust) `base_expr`, looking for a type which either
     /// supports builtin indexing or overloaded indexing.
@@ -73,6 +106,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         base_expr: &hir::Expr<'_>,
         autoderef: &Autoderef<'a, 'tcx>,
         index_ty: Ty<'tcx>,
+        index_expr: &hir::Expr<'_>,
     ) -> Option<(/*index type*/ Ty<'tcx>, /*element type*/ Ty<'tcx>)> {
         let adjusted_ty =
             self.structurally_resolved_type(autoderef.span(), autoderef.final_ty(false));
@@ -82,6 +116,27 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             expr, base_expr, adjusted_ty, index_ty
         );
 
+        if let hir::ExprKind::Unary(
+            hir::UnOp::Neg,
+            hir::Expr {
+                kind: hir::ExprKind::Lit(hir::Lit { node: ast::LitKind::Int(..), .. }),
+                ..
+            },
+        ) = index_expr.kind
+        {
+            match adjusted_ty.kind() {
+                ty::Adt(ty::AdtDef { did, .. }, _)
+                    if self.tcx.is_diagnostic_item(sym::vec_type, *did) =>
+                {
+                    return self.negative_index(adjusted_ty, index_expr.span, base_expr);
+                }
+                ty::Slice(_) | ty::Array(_, _) => {
+                    return self.negative_index(adjusted_ty, index_expr.span, base_expr);
+                }
+                _ => {}
+            }
+        }
+
         for unsize in [false, true] {
             let mut self_ty = adjusted_ty;
             if unsize {
diff --git a/compiler/rustc_typeck/src/check/upvar.rs b/compiler/rustc_typeck/src/check/upvar.rs
index 917bf4ecd8c..1f2ccffa6f2 100644
--- a/compiler/rustc_typeck/src/check/upvar.rs
+++ b/compiler/rustc_typeck/src/check/upvar.rs
@@ -122,6 +122,7 @@ impl<'a, 'tcx> Visitor<'tcx> for InferBorrowKindVisitor<'a, 'tcx> {
 
 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     /// Analysis starting point.
+    #[instrument(skip(self, body), level = "debug")]
     fn analyze_closure(
         &self,
         closure_hir_id: hir::HirId,
@@ -130,8 +131,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         body: &'tcx hir::Body<'tcx>,
         capture_clause: hir::CaptureBy,
     ) {
-        debug!("analyze_closure(id={:?}, body.id={:?})", closure_hir_id, body.id());
-
         // Extract the type of the closure.
         let ty = self.node_ty(closure_hir_id);
         let (closure_def_id, substs) = match *ty.kind() {
@@ -1683,15 +1682,12 @@ struct InferBorrowKind<'a, 'tcx> {
 }
 
 impl<'a, 'tcx> InferBorrowKind<'a, 'tcx> {
+    #[instrument(skip(self), level = "debug")]
     fn adjust_upvar_borrow_kind_for_consume(
         &mut self,
         place_with_id: &PlaceWithHirId<'tcx>,
         diag_expr_id: hir::HirId,
     ) {
-        debug!(
-            "adjust_upvar_borrow_kind_for_consume(place_with_id={:?}, diag_expr_id={:?})",
-            place_with_id, diag_expr_id
-        );
         let tcx = self.fcx.tcx;
         let upvar_id = if let PlaceBase::Upvar(upvar_id) = place_with_id.place.base {
             upvar_id
@@ -1699,7 +1695,7 @@ impl<'a, 'tcx> InferBorrowKind<'a, 'tcx> {
             return;
         };
 
-        debug!("adjust_upvar_borrow_kind_for_consume: upvar={:?}", upvar_id);
+        debug!(?upvar_id);
 
         let usage_span = tcx.hir().span(diag_expr_id);
 
@@ -1718,16 +1714,12 @@ impl<'a, 'tcx> InferBorrowKind<'a, 'tcx> {
     /// Indicates that `place_with_id` is being directly mutated (e.g., assigned
     /// to). If the place is based on a by-ref upvar, this implies that
     /// the upvar must be borrowed using an `&mut` borrow.
+    #[instrument(skip(self), level = "debug")]
     fn adjust_upvar_borrow_kind_for_mut(
         &mut self,
         place_with_id: &PlaceWithHirId<'tcx>,
         diag_expr_id: hir::HirId,
     ) {
-        debug!(
-            "adjust_upvar_borrow_kind_for_mut(place_with_id={:?}, diag_expr_id={:?})",
-            place_with_id, diag_expr_id
-        );
-
         if let PlaceBase::Upvar(_) = place_with_id.place.base {
             // Raw pointers don't inherit mutability
             if place_with_id.place.deref_tys().any(ty::TyS::is_unsafe_ptr) {
@@ -1737,16 +1729,12 @@ impl<'a, 'tcx> InferBorrowKind<'a, 'tcx> {
         }
     }
 
+    #[instrument(skip(self), level = "debug")]
     fn adjust_upvar_borrow_kind_for_unique(
         &mut self,
         place_with_id: &PlaceWithHirId<'tcx>,
         diag_expr_id: hir::HirId,
     ) {
-        debug!(
-            "adjust_upvar_borrow_kind_for_unique(place_with_id={:?}, diag_expr_id={:?})",
-            place_with_id, diag_expr_id
-        );
-
         if let PlaceBase::Upvar(_) = place_with_id.place.base {
             if place_with_id.place.deref_tys().any(ty::TyS::is_unsafe_ptr) {
                 // Raw pointers don't inherit mutability.
@@ -1783,6 +1771,7 @@ impl<'a, 'tcx> InferBorrowKind<'a, 'tcx> {
     /// moving from left to right as needed (but never right to left).
     /// Here the argument `mutbl` is the borrow_kind that is required by
     /// some particular use.
+    #[instrument(skip(self), level = "debug")]
     fn adjust_upvar_borrow_kind(
         &mut self,
         place_with_id: &PlaceWithHirId<'tcx>,
@@ -1791,10 +1780,7 @@ impl<'a, 'tcx> InferBorrowKind<'a, 'tcx> {
     ) {
         let curr_capture_info = self.capture_information[&place_with_id.place];
 
-        debug!(
-            "adjust_upvar_borrow_kind(place={:?}, diag_expr_id={:?}, capture_info={:?}, kind={:?})",
-            place_with_id, diag_expr_id, curr_capture_info, kind
-        );
+        debug!(?curr_capture_info);
 
         if let ty::UpvarCapture::ByValue(_) = curr_capture_info.capture_kind {
             // It's already captured by value, we don't need to do anything here
@@ -1814,6 +1800,7 @@ impl<'a, 'tcx> InferBorrowKind<'a, 'tcx> {
         };
     }
 
+    #[instrument(skip(self, diag_expr_id), level = "debug")]
     fn init_capture_info_for_place(
         &mut self,
         place_with_id: &PlaceWithHirId<'tcx>,
@@ -1840,7 +1827,7 @@ impl<'a, 'tcx> InferBorrowKind<'a, 'tcx> {
 
             self.capture_information.insert(place_with_id.place.clone(), capture_info);
         } else {
-            debug!("Not upvar: {:?}", place_with_id);
+            debug!("Not upvar");
         }
     }
 }
@@ -1867,9 +1854,8 @@ impl<'a, 'tcx> euv::Delegate<'tcx> for InferBorrowKind<'a, 'tcx> {
         }
     }
 
+    #[instrument(skip(self), level = "debug")]
     fn consume(&mut self, place_with_id: &PlaceWithHirId<'tcx>, diag_expr_id: hir::HirId) {
-        debug!("consume(place_with_id={:?}, diag_expr_id={:?})", place_with_id, diag_expr_id);
-
         if !self.capture_information.contains_key(&place_with_id.place) {
             self.init_capture_info_for_place(&place_with_id, diag_expr_id);
         }
@@ -1877,17 +1863,13 @@ impl<'a, 'tcx> euv::Delegate<'tcx> for InferBorrowKind<'a, 'tcx> {
         self.adjust_upvar_borrow_kind_for_consume(&place_with_id, diag_expr_id);
     }
 
+    #[instrument(skip(self), level = "debug")]
     fn borrow(
         &mut self,
         place_with_id: &PlaceWithHirId<'tcx>,
         diag_expr_id: hir::HirId,
         bk: ty::BorrowKind,
     ) {
-        debug!(
-            "borrow(place_with_id={:?}, diag_expr_id={:?}, bk={:?})",
-            place_with_id, diag_expr_id, bk
-        );
-
         // The region here will get discarded/ignored
         let dummy_capture_kind =
             ty::UpvarCapture::ByRef(ty::UpvarBorrow { kind: bk, region: &ty::ReErased });
@@ -1924,9 +1906,8 @@ impl<'a, 'tcx> euv::Delegate<'tcx> for InferBorrowKind<'a, 'tcx> {
         }
     }
 
+    #[instrument(skip(self), level = "debug")]
     fn mutate(&mut self, assignee_place: &PlaceWithHirId<'tcx>, diag_expr_id: hir::HirId) {
-        debug!("mutate(assignee_place={:?}, diag_expr_id={:?})", assignee_place, diag_expr_id);
-
         self.borrow(assignee_place, diag_expr_id, ty::BorrowKind::MutBorrow);
     }
 }
diff --git a/compiler/rustc_typeck/src/check/writeback.rs b/compiler/rustc_typeck/src/check/writeback.rs
index c57ec9ef78f..2c0d926dd01 100644
--- a/compiler/rustc_typeck/src/check/writeback.rs
+++ b/compiler/rustc_typeck/src/check/writeback.rs
@@ -497,6 +497,7 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
             fcx_typeck_results.generator_interior_types.clone();
     }
 
+    #[instrument(skip(self, span), level = "debug")]
     fn visit_opaque_types(&mut self, span: Span) {
         let opaque_types = self.fcx.infcx.inner.borrow().opaque_types.clone();
         for (opaque_type_key, opaque_defn) in opaque_types {
@@ -564,6 +565,7 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
         }
     }
 
+    #[instrument(skip(self, span), level = "debug")]
     fn visit_node_id(&mut self, span: Span, hir_id: hir::HirId) {
         // Export associated path extensions and method resolutions.
         if let Some(def) =
@@ -579,7 +581,7 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
         let n_ty = self.fcx.node_ty(hir_id);
         let n_ty = self.resolve(n_ty, &span);
         self.write_ty_to_typeck_results(hir_id, n_ty);
-        debug!("node {:?} has type {:?}", hir_id, n_ty);
+        debug!(?n_ty);
 
         // Resolve any substitutions
         if let Some(substs) = self.fcx.typeck_results.borrow().node_substs_opt(hir_id) {
@@ -590,31 +592,33 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
         }
     }
 
+    #[instrument(skip(self, span), level = "debug")]
     fn visit_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
         let adjustment = self.fcx.typeck_results.borrow_mut().adjustments_mut().remove(hir_id);
         match adjustment {
             None => {
-                debug!("no adjustments for node {:?}", hir_id);
+                debug!("no adjustments for node");
             }
 
             Some(adjustment) => {
                 let resolved_adjustment = self.resolve(adjustment, &span);
-                debug!("adjustments for node {:?}: {:?}", hir_id, resolved_adjustment);
+                debug!(?resolved_adjustment);
                 self.typeck_results.adjustments_mut().insert(hir_id, resolved_adjustment);
             }
         }
     }
 
+    #[instrument(skip(self, span), level = "debug")]
     fn visit_pat_adjustments(&mut self, span: Span, hir_id: hir::HirId) {
         let adjustment = self.fcx.typeck_results.borrow_mut().pat_adjustments_mut().remove(hir_id);
         match adjustment {
             None => {
-                debug!("no pat_adjustments for node {:?}", hir_id);
+                debug!("no pat_adjustments for node");
             }
 
             Some(adjustment) => {
                 let resolved_adjustment = self.resolve(adjustment, &span);
-                debug!("pat_adjustments for node {:?}: {:?}", hir_id, resolved_adjustment);
+                debug!(?resolved_adjustment);
                 self.typeck_results.pat_adjustments_mut().insert(hir_id, resolved_adjustment);
             }
         }
@@ -732,6 +736,26 @@ impl<'cx, 'tcx> Resolver<'cx, 'tcx> {
     }
 }
 
+struct EraseEarlyRegions<'tcx> {
+    tcx: TyCtxt<'tcx>,
+}
+
+impl<'tcx> TypeFolder<'tcx> for EraseEarlyRegions<'tcx> {
+    fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
+        self.tcx
+    }
+    fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
+        if ty.has_type_flags(ty::TypeFlags::HAS_POTENTIAL_FREE_REGIONS) {
+            ty.super_fold_with(self)
+        } else {
+            ty
+        }
+    }
+    fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
+        if let ty::ReLateBound(..) = r { r } else { self.tcx.lifetimes.re_erased }
+    }
+}
+
 impl<'cx, 'tcx> TypeFolder<'tcx> for Resolver<'cx, 'tcx> {
     fn tcx<'a>(&'a self) -> TyCtxt<'tcx> {
         self.tcx
@@ -739,7 +763,13 @@ impl<'cx, 'tcx> TypeFolder<'tcx> for Resolver<'cx, 'tcx> {
 
     fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
         match self.infcx.fully_resolve(t) {
-            Ok(t) => self.infcx.tcx.erase_regions(t),
+            Ok(t) => {
+                // Do not anonymize late-bound regions
+                // (e.g. keep `for<'a>` named `for<'a>`).
+                // This allows NLL to generate error messages that
+                // refer to the higher-ranked lifetime names written by the user.
+                EraseEarlyRegions { tcx: self.infcx.tcx }.fold_ty(t)
+            }
             Err(_) => {
                 debug!("Resolver::fold_ty: input type `{:?}` not fully resolvable", t);
                 self.report_type_error(t);
diff --git a/compiler/rustc_typeck/src/expr_use_visitor.rs b/compiler/rustc_typeck/src/expr_use_visitor.rs
index ba70006fe96..b5c4d6ac261 100644
--- a/compiler/rustc_typeck/src/expr_use_visitor.rs
+++ b/compiler/rustc_typeck/src/expr_use_visitor.rs
@@ -619,6 +619,8 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
 
         if let Some(hir::Guard::If(ref e)) = arm.guard {
             self.consume_expr(e)
+        } else if let Some(hir::Guard::IfLet(_, ref e)) = arm.guard {
+            self.consume_expr(e)
         }
 
         self.consume_expr(&arm.body);
diff --git a/compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs b/compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs
index 2e3db4d6d65..c2038f4e047 100644
--- a/compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs
+++ b/compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs
@@ -731,7 +731,11 @@ impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> {
     /// Builds the `type defined here` message.
     fn show_definition(&self, err: &mut DiagnosticBuilder<'_>) {
         let mut spans: MultiSpan = if let Some(def_span) = self.tcx.def_ident_span(self.def_id) {
-            def_span.into()
+            if self.tcx.sess.source_map().span_to_snippet(def_span).is_ok() {
+                def_span.into()
+            } else {
+                return;
+            }
         } else {
             return;
         };
diff --git a/library/core/src/cell.rs b/library/core/src/cell.rs
index e56b631dbaf..c0121eebb7f 100644
--- a/library/core/src/cell.rs
+++ b/library/core/src/cell.rs
@@ -1303,6 +1303,11 @@ impl Clone for BorrowRef<'_> {
 ///
 /// See the [module-level documentation](self) for more.
 #[stable(feature = "rust1", since = "1.0.0")]
+#[cfg_attr(
+    not(bootstrap),
+    must_not_suspend = "Holding a Ref across suspend \
+                      points can cause BorrowErrors"
+)]
 pub struct Ref<'b, T: ?Sized + 'b> {
     value: &'b T,
     borrow: BorrowRef<'b>,
@@ -1679,6 +1684,11 @@ impl<'b> BorrowRefMut<'b> {
 ///
 /// See the [module-level documentation](self) for more.
 #[stable(feature = "rust1", since = "1.0.0")]
+#[cfg_attr(
+    not(bootstrap),
+    must_not_suspend = "Holding a RefMut across suspend \
+                      points can cause BorrowErrors"
+)]
 pub struct RefMut<'b, T: ?Sized + 'b> {
     value: &'b mut T,
     borrow: BorrowRefMut<'b>,
diff --git a/library/core/src/convert/mod.rs b/library/core/src/convert/mod.rs
index 1e512af4805..72dbe845c97 100644
--- a/library/core/src/convert/mod.rs
+++ b/library/core/src/convert/mod.rs
@@ -532,9 +532,10 @@ where
 
 // From implies Into
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T, U> Into<U> for T
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl<T, U> const Into<U> for T
 where
-    U: From<T>,
+    U: ~const From<T>,
 {
     fn into(self) -> U {
         U::from(self)
@@ -543,7 +544,8 @@ where
 
 // From (and thus Into) is reflexive
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T> From<T> for T {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl<T> const From<T> for T {
     fn from(t: T) -> T {
         t
     }
diff --git a/library/core/src/fmt/mod.rs b/library/core/src/fmt/mod.rs
index 3a0c19d7de5..31da3ef87b9 100644
--- a/library/core/src/fmt/mod.rs
+++ b/library/core/src/fmt/mod.rs
@@ -270,9 +270,10 @@ pub struct ArgumentV1<'a> {
 /// of `format_args!(..)` and reduce the scope of the `unsafe` block.
 #[allow(missing_debug_implementations)]
 #[doc(hidden)]
-#[non_exhaustive]
 #[unstable(feature = "fmt_internals", reason = "internal to format_args!", issue = "none")]
-pub struct UnsafeArg;
+pub struct UnsafeArg {
+    _private: (),
+}
 
 impl UnsafeArg {
     /// See documentation where `UnsafeArg` is required to know when it is safe to
@@ -281,7 +282,7 @@ impl UnsafeArg {
     #[unstable(feature = "fmt_internals", reason = "internal to format_args!", issue = "none")]
     #[inline(always)]
     pub unsafe fn new() -> Self {
-        Self
+        Self { _private: () }
     }
 }
 
diff --git a/library/core/src/iter/range.rs b/library/core/src/iter/range.rs
index f7ed811e447..0f835689699 100644
--- a/library/core/src/iter/range.rs
+++ b/library/core/src/iter/range.rs
@@ -673,6 +673,11 @@ impl<A: Step> Iterator for ops::Range<A> {
     }
 
     #[inline]
+    fn is_sorted(self) -> bool {
+        true
+    }
+
+    #[inline]
     #[doc(hidden)]
     unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item
     where
@@ -1095,6 +1100,11 @@ impl<A: Step> Iterator for ops::RangeInclusive<A> {
     fn max(mut self) -> Option<A> {
         self.next_back()
     }
+
+    #[inline]
+    fn is_sorted(self) -> bool {
+        true
+    }
 }
 
 #[stable(feature = "inclusive_range", since = "1.26.0")]
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 265ba9f1bb9..4408b5a3d20 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -82,6 +82,7 @@
 #![feature(const_float_bits_conv)]
 #![feature(const_float_classify)]
 #![feature(const_heap)]
+#![feature(const_convert)]
 #![feature(const_inherent_unchecked_arith)]
 #![feature(const_int_unchecked_arith)]
 #![feature(const_intrinsic_copy)]
@@ -141,6 +142,7 @@
 #![feature(link_llvm_intrinsics)]
 #![feature(llvm_asm)]
 #![feature(min_specialization)]
+#![cfg_attr(not(bootstrap), feature(must_not_suspend))]
 #![feature(negative_impls)]
 #![feature(never_type)]
 #![feature(no_core)]
diff --git a/library/core/src/option.rs b/library/core/src/option.rs
index 94d892dd787..a162c0340fb 100644
--- a/library/core/src/option.rs
+++ b/library/core/src/option.rs
@@ -2019,7 +2019,8 @@ impl<A, V: FromIterator<A>> FromIterator<Option<A>> for Option<V> {
 }
 
 #[unstable(feature = "try_trait_v2", issue = "84277")]
-impl<T> ops::Try for Option<T> {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl<T> const ops::Try for Option<T> {
     type Output = T;
     type Residual = Option<convert::Infallible>;
 
@@ -2038,7 +2039,8 @@ impl<T> ops::Try for Option<T> {
 }
 
 #[unstable(feature = "try_trait_v2", issue = "84277")]
-impl<T> ops::FromResidual for Option<T> {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl<T> const ops::FromResidual for Option<T> {
     #[inline]
     fn from_residual(residual: Option<convert::Infallible>) -> Self {
         match residual {
diff --git a/library/core/src/result.rs b/library/core/src/result.rs
index 4a300f857e9..bd4e623732e 100644
--- a/library/core/src/result.rs
+++ b/library/core/src/result.rs
@@ -1889,7 +1889,8 @@ impl<A, E, V: FromIterator<A>> FromIterator<Result<A, E>> for Result<V, E> {
 }
 
 #[unstable(feature = "try_trait_v2", issue = "84277")]
-impl<T, E> ops::Try for Result<T, E> {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl<T, E> const ops::Try for Result<T, E> {
     type Output = T;
     type Residual = Result<convert::Infallible, E>;
 
@@ -1908,7 +1909,10 @@ impl<T, E> ops::Try for Result<T, E> {
 }
 
 #[unstable(feature = "try_trait_v2", issue = "84277")]
-impl<T, E, F: From<E>> ops::FromResidual<Result<convert::Infallible, E>> for Result<T, F> {
+#[rustc_const_unstable(feature = "const_convert", issue = "88674")]
+impl<T, E, F: ~const From<E>> const ops::FromResidual<Result<convert::Infallible, E>>
+    for Result<T, F>
+{
     #[inline]
     fn from_residual(residual: Result<convert::Infallible, E>) -> Self {
         match residual {
diff --git a/library/core/src/slice/sort.rs b/library/core/src/slice/sort.rs
index 8a31388fbdb..60b39295caf 100644
--- a/library/core/src/slice/sort.rs
+++ b/library/core/src/slice/sort.rs
@@ -6,8 +6,6 @@
 //! Unstable sorting is compatible with libcore because it doesn't allocate memory, unlike our
 //! stable sorting implementation.
 
-// ignore-tidy-undocumented-unsafe
-
 use crate::cmp;
 use crate::mem::{self, MaybeUninit};
 use crate::ptr;
@@ -291,6 +289,9 @@ where
             } else if start_r < end_r {
                 block_l = rem;
             } else {
+                // There were the same number of elements to switch on both blocks during the last
+                // iteration, so there are no remaining elements on either block. Cover the remaining
+                // items with roughly equally-sized blocks.
                 block_l = rem / 2;
                 block_r = rem - block_l;
             }
@@ -437,6 +438,17 @@ where
         // Move its remaining out-of-order elements to the far right.
         debug_assert_eq!(width(l, r), block_l);
         while start_l < end_l {
+            // remaining-elements-safety
+            // SAFETY: while the loop condition holds there are still elements in `offsets_l`, so it
+            // is safe to point `end_l` to the previous element.
+            //
+            // The `ptr::swap` is safe if both its arguments are valid for reads and writes:
+            //  - Per the debug assert above, the distance between `l` and `r` is `block_l`
+            //    elements, so there can be at most `block_l` remaining offsets between `start_l`
+            //    and `end_l`. This means `r` will be moved at most `block_l` steps back, which
+            //    makes the `r.offset` calls valid (at that point `l == r`).
+            //  - `offsets_l` contains valid offsets into `v` collected during the partitioning of
+            //    the last block, so the `l.offset` calls are valid.
             unsafe {
                 end_l = end_l.offset(-1);
                 ptr::swap(l.offset(*end_l as isize), r.offset(-1));
@@ -449,6 +461,7 @@ where
         // Move its remaining out-of-order elements to the far left.
         debug_assert_eq!(width(l, r), block_r);
         while start_r < end_r {
+            // SAFETY: See the reasoning in [remaining-elements-safety].
             unsafe {
                 end_r = end_r.offset(-1);
                 ptr::swap(l, r.offset(-(*end_r as isize) - 1));
@@ -481,6 +494,8 @@ where
 
         // Read the pivot into a stack-allocated variable for efficiency. If a following comparison
         // operation panics, the pivot will be automatically written back into the slice.
+
+        // SAFETY: `pivot` is a reference to the first element of `v`, so `ptr::read` is safe.
         let mut tmp = mem::ManuallyDrop::new(unsafe { ptr::read(pivot) });
         let _pivot_guard = CopyOnDrop { src: &mut *tmp, dest: pivot };
         let pivot = &*tmp;
@@ -646,6 +661,12 @@ where
 
     if len >= 8 {
         // Swaps indices so that `v[a] <= v[b]`.
+        // SAFETY: `len >= 8` so there are at least two elements in the neighborhoods of
+        // `a`, `b` and `c`. This means the three calls to `sort_adjacent` result in
+        // corresponding calls to `sort3` with valid 3-item neighborhoods around each
+        // pointer, which in turn means the calls to `sort2` are done with valid
+        // references. Thus the `v.get_unchecked` calls are safe, as is the `ptr::swap`
+        // call.
         let mut sort2 = |a: &mut usize, b: &mut usize| unsafe {
             if is_less(v.get_unchecked(*b), v.get_unchecked(*a)) {
                 ptr::swap(a, b);
diff --git a/library/core/tests/convert.rs b/library/core/tests/convert.rs
new file mode 100644
index 00000000000..f1048f4cf09
--- /dev/null
+++ b/library/core/tests/convert.rs
@@ -0,0 +1,16 @@
+#[test]
+fn convert() {
+    const fn from(x: i32) -> i32 {
+        i32::from(x)
+    }
+
+    const FOO: i32 = from(42);
+    assert_eq!(FOO, 42);
+
+    const fn into(x: Vec<String>) -> Vec<String> {
+        x.into()
+    }
+
+    const BAR: Vec<String> = into(Vec::new());
+    assert_eq!(BAR, Vec::<String>::new());
+}
diff --git a/library/core/tests/lib.rs b/library/core/tests/lib.rs
index cd3aed4cd28..f25106abc88 100644
--- a/library/core/tests/lib.rs
+++ b/library/core/tests/lib.rs
@@ -9,12 +9,13 @@
 #![feature(cfg_target_has_atomic)]
 #![feature(const_assume)]
 #![feature(const_cell_into_inner)]
+#![feature(const_convert)]
 #![feature(const_maybe_uninit_assume_init)]
+#![feature(const_num_from_num)]
 #![feature(const_ptr_read)]
 #![feature(const_ptr_write)]
 #![feature(const_ptr_offset)]
 #![feature(const_trait_impl)]
-#![feature(const_num_from_num)]
 #![feature(core_intrinsics)]
 #![feature(core_private_bignum)]
 #![feature(core_private_diy_float)]
@@ -83,6 +84,7 @@ mod char;
 mod clone;
 mod cmp;
 mod const_ptr;
+mod convert;
 mod fmt;
 mod hash;
 mod intrinsics;
diff --git a/library/std/src/ffi/c_str.rs b/library/std/src/ffi/c_str.rs
index ba084987f66..fe1f28f00c4 100644
--- a/library/std/src/ffi/c_str.rs
+++ b/library/std/src/ffi/c_str.rs
@@ -409,6 +409,8 @@ impl CString {
     /// Creates a C-compatible string by consuming a byte vector,
     /// without checking for interior 0 bytes.
     ///
+    /// Trailing 0 byte will be appended by this function.
+    ///
     /// This method is equivalent to [`CString::new`] except that no runtime
     /// assertion is made that `v` contains no 0 bytes, and it requires an
     /// actual byte vector, not anything that can be converted to one with Into.
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index f69baba9e73..b33a3c5d22f 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -297,6 +297,7 @@
 #![feature(maybe_uninit_slice)]
 #![feature(maybe_uninit_uninit_array)]
 #![feature(min_specialization)]
+#![cfg_attr(not(bootstrap), feature(must_not_suspend))]
 #![feature(needs_panic_runtime)]
 #![feature(negative_impls)]
 #![feature(never_type)]
@@ -520,20 +521,20 @@ pub mod task {
     pub use alloc::task::*;
 }
 
-// Platform-abstraction modules
+// The runtime entry point and a few unstable public functions used by the
+// compiler
 #[macro_use]
-mod sys_common;
+pub mod rt;
+
+// Platform-abstraction modules
 mod sys;
+mod sys_common;
 
 pub mod alloc;
 
 // Private support modules
 mod panicking;
 
-// The runtime entry point and a few unstable public functions used by the
-// compiler
-pub mod rt;
-
 #[path = "../../backtrace/src/lib.rs"]
 #[allow(dead_code, unused_attributes)]
 mod backtrace_rs;
diff --git a/library/std/src/process.rs b/library/std/src/process.rs
index c9b21fcf9c6..5c68400114d 100644
--- a/library/std/src/process.rs
+++ b/library/std/src/process.rs
@@ -1907,7 +1907,7 @@ impl Child {
 /// [platform-specific behavior]: #platform-specific-behavior
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn exit(code: i32) -> ! {
-    crate::sys_common::rt::cleanup();
+    crate::rt::cleanup();
     crate::sys::os::exit(code)
 }
 
diff --git a/library/std/src/rt.rs b/library/std/src/rt.rs
index 893167e3730..4d72aff0116 100644
--- a/library/std/src/rt.rs
+++ b/library/std/src/rt.rs
@@ -13,11 +13,93 @@
     issue = "none"
 )]
 #![doc(hidden)]
+#![deny(unsafe_op_in_unsafe_fn)]
+#![allow(unused_macros)]
+
+use crate::ffi::CString;
 
 // Re-export some of our utilities which are expected by other crates.
 pub use crate::panicking::{begin_panic, begin_panic_fmt, panic_count};
 pub use core::panicking::panic_display;
 
+use crate::sync::Once;
+use crate::sys;
+use crate::sys_common::thread_info;
+use crate::thread::Thread;
+
+// Prints to the "panic output", depending on the platform this may be:
+// - the standard error output
+// - some dedicated platform specific output
+// - nothing (so this macro is a no-op)
+macro_rules! rtprintpanic {
+    ($($t:tt)*) => {
+        if let Some(mut out) = crate::sys::stdio::panic_output() {
+            let _ = crate::io::Write::write_fmt(&mut out, format_args!($($t)*));
+        }
+    }
+}
+
+macro_rules! rtabort {
+    ($($t:tt)*) => {
+        {
+            rtprintpanic!("fatal runtime error: {}\n", format_args!($($t)*));
+            crate::sys::abort_internal();
+        }
+    }
+}
+
+macro_rules! rtassert {
+    ($e:expr) => {
+        if !$e {
+            rtabort!(concat!("assertion failed: ", stringify!($e)));
+        }
+    };
+}
+
+macro_rules! rtunwrap {
+    ($ok:ident, $e:expr) => {
+        match $e {
+            $ok(v) => v,
+            ref err => {
+                let err = err.as_ref().map(drop); // map Ok/Some which might not be Debug
+                rtabort!(concat!("unwrap failed: ", stringify!($e), " = {:?}"), err)
+            }
+        }
+    };
+}
+
+// One-time runtime initialization.
+// Runs before `main`.
+// SAFETY: must be called only once during runtime initialization.
+// NOTE: this is not guaranteed to run, for example when Rust code is called externally.
+#[cfg_attr(test, allow(dead_code))]
+unsafe fn init(argc: isize, argv: *const *const u8) {
+    unsafe {
+        sys::init(argc, argv);
+
+        let main_guard = sys::thread::guard::init();
+        // Next, set up the current Thread with the guard information we just
+        // created. Note that this isn't necessary in general for new threads,
+        // but we just do this to name the main thread and to give it correct
+        // info about the stack bounds.
+        let thread = Thread::new(Some(rtunwrap!(Ok, CString::new("main"))));
+        thread_info::set(main_guard, thread);
+    }
+}
+
+// One-time runtime cleanup.
+// Runs after `main` or at program exit.
+// NOTE: this is not guaranteed to run, for example when the program aborts.
+pub(crate) fn cleanup() {
+    static CLEANUP: Once = Once::new();
+    CLEANUP.call_once(|| unsafe {
+        // Flush stdout and disable buffering.
+        crate::io::cleanup();
+        // SAFETY: Only called once during runtime cleanup.
+        sys::cleanup();
+    });
+}
+
 // To reduce the generated code of the new `lang_start`, this function is doing
 // the real work.
 #[cfg(not(test))]
@@ -26,7 +108,7 @@ fn lang_start_internal(
     argc: isize,
     argv: *const *const u8,
 ) -> Result<isize, !> {
-    use crate::{mem, panic, sys, sys_common};
+    use crate::{mem, panic};
     let rt_abort = move |e| {
         mem::forget(e);
         rtabort!("initialization or cleanup bug");
@@ -42,14 +124,14 @@ fn lang_start_internal(
     // prevent libstd from accidentally introducing a panic to these functions. Another is from
     // user code from `main` or, more nefariously, as described in e.g. issue #86030.
     // SAFETY: Only called once during runtime initialization.
-    panic::catch_unwind(move || unsafe { sys_common::rt::init(argc, argv) }).map_err(rt_abort)?;
+    panic::catch_unwind(move || unsafe { init(argc, argv) }).map_err(rt_abort)?;
     let ret_code = panic::catch_unwind(move || panic::catch_unwind(main).unwrap_or(101) as isize)
         .map_err(move |e| {
             mem::forget(e);
             rtprintpanic!("drop of the panic payload panicked");
             sys::abort_internal()
         });
-    panic::catch_unwind(sys_common::rt::cleanup).map_err(rt_abort)?;
+    panic::catch_unwind(cleanup).map_err(rt_abort)?;
     ret_code
 }
 
diff --git a/library/std/src/sync/mutex.rs b/library/std/src/sync/mutex.rs
index e1d6324c17e..06a97fd3f76 100644
--- a/library/std/src/sync/mutex.rs
+++ b/library/std/src/sync/mutex.rs
@@ -188,6 +188,12 @@ unsafe impl<T: ?Sized + Send> Sync for Mutex<T> {}
 /// [`lock`]: Mutex::lock
 /// [`try_lock`]: Mutex::try_lock
 #[must_use = "if unused the Mutex will immediately unlock"]
+#[cfg_attr(
+    not(bootstrap),
+    must_not_suspend = "Holding a MutexGuard across suspend \
+                      points can cause deadlocks, delays, \
+                      and cause Futures to not implement `Send`"
+)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct MutexGuard<'a, T: ?Sized + 'a> {
     lock: &'a Mutex<T>,
diff --git a/library/std/src/sync/rwlock.rs b/library/std/src/sync/rwlock.rs
index e50d62d8173..aa1ce82d967 100644
--- a/library/std/src/sync/rwlock.rs
+++ b/library/std/src/sync/rwlock.rs
@@ -95,6 +95,12 @@ unsafe impl<T: ?Sized + Send + Sync> Sync for RwLock<T> {}
 /// [`read`]: RwLock::read
 /// [`try_read`]: RwLock::try_read
 #[must_use = "if unused the RwLock will immediately unlock"]
+#[cfg_attr(
+    not(bootstrap),
+    must_not_suspend = "Holding a RwLockReadGuard across suspend \
+                      points can cause deadlocks, delays, \
+                      and cause Futures to not implement `Send`"
+)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct RwLockReadGuard<'a, T: ?Sized + 'a> {
     lock: &'a RwLock<T>,
@@ -115,6 +121,12 @@ unsafe impl<T: ?Sized + Sync> Sync for RwLockReadGuard<'_, T> {}
 /// [`write`]: RwLock::write
 /// [`try_write`]: RwLock::try_write
 #[must_use = "if unused the RwLock will immediately unlock"]
+#[cfg_attr(
+    not(bootstrap),
+    must_not_suspend = "Holding a RwLockWriteGuard across suspend \
+                      points can cause deadlocks, delays, \
+                      and cause Future's to not implement `Send`"
+)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct RwLockWriteGuard<'a, T: ?Sized + 'a> {
     lock: &'a RwLock<T>,
diff --git a/library/std/src/sys/unix/mod.rs b/library/std/src/sys/unix/mod.rs
index f5424e3d282..1c37f4ee498 100644
--- a/library/std/src/sys/unix/mod.rs
+++ b/library/std/src/sys/unix/mod.rs
@@ -120,7 +120,7 @@ pub unsafe fn init(argc: isize, argv: *const *const u8) {
 
     unsafe fn reset_sigpipe() {
         #[cfg(not(any(target_os = "emscripten", target_os = "fuchsia")))]
-        assert!(signal(libc::SIGPIPE, libc::SIG_IGN) != libc::SIG_ERR);
+        rtassert!(signal(libc::SIGPIPE, libc::SIG_IGN) != libc::SIG_ERR);
     }
 }
 
diff --git a/library/std/src/sys/unix/thread.rs b/library/std/src/sys/unix/thread.rs
index 133ad3ea420..05f51a46168 100644
--- a/library/std/src/sys/unix/thread.rs
+++ b/library/std/src/sys/unix/thread.rs
@@ -338,8 +338,17 @@ pub fn available_concurrency() -> io::Result<NonZeroUsize> {
             }
 
             Ok(unsafe { NonZeroUsize::new_unchecked(cpus as usize) })
+        } else if #[cfg(target_os = "haiku")] {
+            let mut sinfo: libc::system_info = crate::mem::zeroed();
+            let res = libc::get_system_info(&mut sinfo);
+
+            if res != libc::B_OK {
+                return Err(io::Error::last_os_error());
+            }
+
+            Ok(unsafe { NonZeroUsize::new_unchecked(sinfo.cpu_count as usize) })
         } else {
-            // FIXME: implement on vxWorks, Redox, Haiku, l4re
+            // FIXME: implement on vxWorks, Redox, l4re
             Err(io::Error::new_const(io::ErrorKind::Unsupported, &"Getting the number of hardware threads is not supported on the target platform"))
         }
     }
diff --git a/library/std/src/sys_common/mod.rs b/library/std/src/sys_common/mod.rs
index 894440564b7..5a5913ebd79 100644
--- a/library/std/src/sys_common/mod.rs
+++ b/library/std/src/sys_common/mod.rs
@@ -28,8 +28,6 @@ pub mod memchr;
 pub mod mutex;
 pub mod process;
 pub mod remutex;
-#[macro_use]
-pub mod rt;
 pub mod rwlock;
 pub mod thread;
 pub mod thread_info;
diff --git a/library/std/src/sys_common/rt.rs b/library/std/src/sys_common/rt.rs
deleted file mode 100644
index 02013ecc4ce..00000000000
--- a/library/std/src/sys_common/rt.rs
+++ /dev/null
@@ -1,81 +0,0 @@
-#![deny(unsafe_op_in_unsafe_fn)]
-#![allow(unused_macros)]
-
-use crate::sync::Once;
-use crate::sys;
-use crate::sys_common::thread_info;
-use crate::thread::Thread;
-
-// One-time runtime initialization.
-// Runs before `main`.
-// SAFETY: must be called only once during runtime initialization.
-// NOTE: this is not guaranteed to run, for example when Rust code is called externally.
-#[cfg_attr(test, allow(dead_code))]
-pub unsafe fn init(argc: isize, argv: *const *const u8) {
-    unsafe {
-        sys::init(argc, argv);
-
-        let main_guard = sys::thread::guard::init();
-        // Next, set up the current Thread with the guard information we just
-        // created. Note that this isn't necessary in general for new threads,
-        // but we just do this to name the main thread and to give it correct
-        // info about the stack bounds.
-        let thread = Thread::new(Some("main".to_owned()));
-        thread_info::set(main_guard, thread);
-    }
-}
-
-// One-time runtime cleanup.
-// Runs after `main` or at program exit.
-// NOTE: this is not guaranteed to run, for example when the program aborts.
-#[cfg_attr(test, allow(dead_code))]
-pub fn cleanup() {
-    static CLEANUP: Once = Once::new();
-    CLEANUP.call_once(|| unsafe {
-        // Flush stdout and disable buffering.
-        crate::io::cleanup();
-        // SAFETY: Only called once during runtime cleanup.
-        sys::cleanup();
-    });
-}
-
-// Prints to the "panic output", depending on the platform this may be:
-// - the standard error output
-// - some dedicated platform specific output
-// - nothing (so this macro is a no-op)
-macro_rules! rtprintpanic {
-    ($($t:tt)*) => {
-        if let Some(mut out) = crate::sys::stdio::panic_output() {
-            let _ = crate::io::Write::write_fmt(&mut out, format_args!($($t)*));
-        }
-    }
-}
-
-macro_rules! rtabort {
-    ($($t:tt)*) => {
-        {
-            rtprintpanic!("fatal runtime error: {}\n", format_args!($($t)*));
-            crate::sys::abort_internal();
-        }
-    }
-}
-
-macro_rules! rtassert {
-    ($e:expr) => {
-        if !$e {
-            rtabort!(concat!("assertion failed: ", stringify!($e)));
-        }
-    };
-}
-
-macro_rules! rtunwrap {
-    ($ok:ident, $e:expr) => {
-        match $e {
-            $ok(v) => v,
-            ref err => {
-                let err = err.as_ref().map(drop); // map Ok/Some which might not be Debug
-                rtabort!(concat!("unwrap failed: ", stringify!($e), " = {:?}"), err)
-            }
-        }
-    };
-}
diff --git a/library/std/src/sys_common/thread_info.rs b/library/std/src/sys_common/thread_info.rs
index f09d16c33e6..38c9e50009a 100644
--- a/library/std/src/sys_common/thread_info.rs
+++ b/library/std/src/sys_common/thread_info.rs
@@ -1,4 +1,5 @@
 #![allow(dead_code)] // stack_guard isn't used right now on all platforms
+#![allow(unused_unsafe)] // thread_local with `const {}` triggers this liny
 
 use crate::cell::RefCell;
 use crate::sys::thread::guard::Guard;
@@ -9,7 +10,7 @@ struct ThreadInfo {
     thread: Thread,
 }
 
-thread_local! { static THREAD_INFO: RefCell<Option<ThreadInfo>> = RefCell::new(None) }
+thread_local! { static THREAD_INFO: RefCell<Option<ThreadInfo>> = const { RefCell::new(None) } }
 
 impl ThreadInfo {
     fn with<R, F>(f: F) -> Option<R>
@@ -17,12 +18,13 @@ impl ThreadInfo {
         F: FnOnce(&mut ThreadInfo) -> R,
     {
         THREAD_INFO
-            .try_with(move |c| {
-                if c.borrow().is_none() {
-                    *c.borrow_mut() =
-                        Some(ThreadInfo { stack_guard: None, thread: Thread::new(None) })
-                }
-                f(c.borrow_mut().as_mut().unwrap())
+            .try_with(move |thread_info| {
+                let mut thread_info = thread_info.borrow_mut();
+                let thread_info = thread_info.get_or_insert_with(|| ThreadInfo {
+                    stack_guard: None,
+                    thread: Thread::new(None),
+                });
+                f(thread_info)
             })
             .ok()
     }
@@ -37,10 +39,9 @@ pub fn stack_guard() -> Option<Guard> {
 }
 
 pub fn set(stack_guard: Option<Guard>, thread: Thread) {
-    THREAD_INFO.with(|c| assert!(c.borrow().is_none()));
-    THREAD_INFO.with(move |c| *c.borrow_mut() = Some(ThreadInfo { stack_guard, thread }));
-}
-
-pub fn reset_guard(stack_guard: Option<Guard>) {
-    THREAD_INFO.with(move |c| c.borrow_mut().as_mut().unwrap().stack_guard = stack_guard);
+    THREAD_INFO.with(move |thread_info| {
+        let mut thread_info = thread_info.borrow_mut();
+        rtassert!(thread_info.is_none());
+        *thread_info = Some(ThreadInfo { stack_guard, thread });
+    });
 }
diff --git a/library/std/src/thread/mod.rs b/library/std/src/thread/mod.rs
index f44df845bf4..9d659102b03 100644
--- a/library/std/src/thread/mod.rs
+++ b/library/std/src/thread/mod.rs
@@ -457,7 +457,9 @@ impl Builder {
 
         let stack_size = stack_size.unwrap_or_else(thread::min_stack);
 
-        let my_thread = Thread::new(name);
+        let my_thread = Thread::new(name.map(|name| {
+            CString::new(name).expect("thread name may not contain interior null bytes")
+        }));
         let their_thread = my_thread.clone();
 
         let my_packet: Arc<UnsafeCell<Option<Result<T>>>> = Arc::new(UnsafeCell::new(None));
@@ -1073,12 +1075,8 @@ pub struct Thread {
 impl Thread {
     // Used only internally to construct a thread object without spawning
     // Panics if the name contains nuls.
-    pub(crate) fn new(name: Option<String>) -> Thread {
-        let cname =
-            name.map(|n| CString::new(n).expect("thread name may not contain interior null bytes"));
-        Thread {
-            inner: Arc::new(Inner { name: cname, id: ThreadId::new(), parker: Parker::new() }),
-        }
+    pub(crate) fn new(name: Option<CString>) -> Thread {
+        Thread { inner: Arc::new(Inner { name, id: ThreadId::new(), parker: Parker::new() }) }
     }
 
     /// Atomically makes the handle's token available if it is not already.
diff --git a/library/test/src/formatters/junit.rs b/library/test/src/formatters/junit.rs
index aa244807514..04057906d1c 100644
--- a/library/test/src/formatters/junit.rs
+++ b/library/test/src/formatters/junit.rs
@@ -29,7 +29,8 @@ impl<T: Write> JunitFormatter<T> {
 impl<T: Write> OutputFormatter for JunitFormatter<T> {
     fn write_run_start(&mut self, _test_count: usize) -> io::Result<()> {
         // We write xml header on run start
-        self.write_message(&"<?xml version=\"1.0\" encoding=\"UTF-8\"?>")
+        self.out.write_all(b"\n")?;
+        self.write_message("<?xml version=\"1.0\" encoding=\"UTF-8\"?>")
     }
 
     fn write_test_start(&mut self, _desc: &TestDesc) -> io::Result<()> {
@@ -133,6 +134,8 @@ impl<T: Write> OutputFormatter for JunitFormatter<T> {
         self.write_message("</testsuite>")?;
         self.write_message("</testsuites>")?;
 
+        self.out.write_all(b"\n\n")?;
+
         Ok(state.failed == 0)
     }
 }
diff --git a/rustfmt.toml b/rustfmt.toml
index 480b19a5e93..053f3e3ee58 100644
--- a/rustfmt.toml
+++ b/rustfmt.toml
@@ -19,6 +19,7 @@ ignore = [
     "library/backtrace",
     "library/stdarch",
     "compiler/rustc_codegen_cranelift",
+    "compiler/rustc_codegen_gcc",
     "src/doc/book",
     "src/doc/edition-guide",
     "src/doc/embedded-book",
diff --git a/src/bootstrap/check.rs b/src/bootstrap/check.rs
index f66f282bea9..28e7f1fdca7 100644
--- a/src/bootstrap/check.rs
+++ b/src/bootstrap/check.rs
@@ -243,11 +243,16 @@ impl Step for CodegenBackend {
     const DEFAULT: bool = true;
 
     fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
-        run.paths(&["compiler/rustc_codegen_cranelift", "rustc_codegen_cranelift"])
+        run.paths(&[
+            "compiler/rustc_codegen_cranelift",
+            "rustc_codegen_cranelift",
+            "compiler/rustc_codegen_gcc",
+            "rustc_codegen_gcc",
+        ])
     }
 
     fn make_run(run: RunConfig<'_>) {
-        for &backend in &[INTERNER.intern_str("cranelift")] {
+        for &backend in &[INTERNER.intern_str("cranelift"), INTERNER.intern_str("gcc")] {
             run.builder.ensure(CodegenBackend { target: run.target, backend });
         }
     }
diff --git a/src/bootstrap/defaults/config.library.toml b/src/bootstrap/defaults/config.library.toml
index 9874fdb767f..7bc054d3a49 100644
--- a/src/bootstrap/defaults/config.library.toml
+++ b/src/bootstrap/defaults/config.library.toml
@@ -10,6 +10,5 @@ bench-stage = 0
 incremental = true
 
 [llvm]
-# Will download LLVM from CI if available on your platform (Linux only for now)
-# https://github.com/rust-lang/rust/issues/77084 tracks support for more platforms
+# Will download LLVM from CI if available on your platform.
 download-ci-llvm = "if-available"
diff --git a/src/bootstrap/setup.rs b/src/bootstrap/setup.rs
index a5829dfa9d8..5bc0a505bf6 100644
--- a/src/bootstrap/setup.rs
+++ b/src/bootstrap/setup.rs
@@ -1,3 +1,4 @@
+use crate::TargetSelection;
 use crate::{t, VERSION};
 use std::fmt::Write as _;
 use std::path::{Path, PathBuf};
@@ -107,6 +108,17 @@ pub fn setup(src_path: &Path, profile: Profile) {
     let include_path = profile.include_path(src_path);
     println!("`x.py` will now use the configuration at {}", include_path.display());
 
+    let build = TargetSelection::from_user(&env!("BUILD_TRIPLE"));
+    let stage_path = ["build", build.rustc_target_arg(), "stage1"].join("/");
+
+    println!();
+
+    if !rustup_installed() && profile != Profile::User {
+        println!("`rustup` is not installed; cannot link `stage1` toolchain");
+    } else if stage_dir_exists(&stage_path[..]) {
+        attempt_toolchain_link(&stage_path[..]);
+    }
+
     let suggestions = match profile {
         Profile::Codegen | Profile::Compiler => &["check", "build", "test"][..],
         Profile::Tools => &[
@@ -139,6 +151,74 @@ pub fn setup(src_path: &Path, profile: Profile) {
     }
 }
 
+fn rustup_installed() -> bool {
+    Command::new("rustup")
+        .arg("--version")
+        .stdout(std::process::Stdio::null())
+        .output()
+        .map_or(false, |output| output.status.success())
+}
+
+fn stage_dir_exists(stage_path: &str) -> bool {
+    match fs::create_dir(&stage_path[..]) {
+        Ok(_) => true,
+        Err(_) => Path::new(&stage_path[..]).exists(),
+    }
+}
+
+fn attempt_toolchain_link(stage_path: &str) {
+    if toolchain_is_linked() {
+        return;
+    }
+
+    if try_link_toolchain(&stage_path[..]) {
+        println!(
+            "Added `stage1` rustup toolchain; try `cargo +stage1 build` on a separate rust project to run a newly-built toolchain"
+        );
+    } else {
+        println!("`rustup` failed to link stage 1 build to `stage1` toolchain");
+        println!(
+            "To manually link stage 1 build to `stage1` toolchain, run:\n
+            `rustup toolchain link stage1 {}`",
+            &stage_path[..]
+        );
+    }
+}
+
+fn toolchain_is_linked() -> bool {
+    match Command::new("rustup")
+        .args(&["toolchain", "list"])
+        .stdout(std::process::Stdio::piped())
+        .output()
+    {
+        Ok(toolchain_list) => {
+            if !String::from_utf8_lossy(&toolchain_list.stdout).contains("stage1") {
+                return false;
+            }
+            // The toolchain has already been linked.
+            println!(
+                "`stage1` toolchain already linked; not attempting to link `stage1` toolchain"
+            );
+        }
+        Err(_) => {
+            // In this case, we don't know if the `stage1` toolchain has been linked;
+            // but `rustup` failed, so let's not go any further.
+            println!(
+                "`rustup` failed to list current toolchains; not attempting to link `stage1` toolchain"
+            );
+        }
+    }
+    true
+}
+
+fn try_link_toolchain(stage_path: &str) -> bool {
+    Command::new("rustup")
+        .stdout(std::process::Stdio::null())
+        .args(&["toolchain", "link", "stage1", &stage_path[..]])
+        .output()
+        .map_or(false, |output| output.status.success())
+}
+
 // Used to get the path for `Subcommand::Setup`
 pub fn interactive_path() -> io::Result<Profile> {
     fn abbrev_all() -> impl Iterator<Item = ((String, String), Profile)> {
diff --git a/src/ci/scripts/install-clang.sh b/src/ci/scripts/install-clang.sh
index fd29d3a022a..b17398bb6b4 100755
--- a/src/ci/scripts/install-clang.sh
+++ b/src/ci/scripts/install-clang.sh
@@ -61,3 +61,9 @@ elif isWindows && [[ ${CUSTOM_MINGW-0} -ne 1 ]]; then
     ciCommandSetEnv RUST_CONFIGURE_ARGS \
         "${RUST_CONFIGURE_ARGS} --set llvm.clang-cl=$(pwd)/clang-rust/bin/clang-cl.exe"
 fi
+
+if isWindows; then
+    # GitHub image 20210928.2 added LLVM, but it is broken (and we don't want
+    # to use it anyways).
+    rm -rf /c/Program\ Files/LLVM
+fi
diff --git a/src/doc/book b/src/doc/book
-Subproject fcb5e0ea68112d85a1d29a7a7335978ef2a0218
+Subproject eb1282ec444db94055fa9531b6f3f803e86bb38
diff --git a/src/doc/nomicon b/src/doc/nomicon
-Subproject fe6227eb3c8533200c52dffa42ef1b6f2f02c40
+Subproject 2747c4bb2cbc0639b733793ddb0bf4e9daa2634
diff --git a/src/doc/reference b/src/doc/reference
-Subproject 0e5ed7a4bec065f0cc18c35d1c904639e095314
+Subproject 13747275bd14c2d2b453100498532f9ae550476
diff --git a/src/doc/rust-by-example b/src/doc/rust-by-example
-Subproject 9d4132b56c4999cd3ce1aeca5f1b2f2cb0d11c2
+Subproject 28aca4a36962c709bce301c03114b5589381dfb
diff --git a/src/doc/rustc-dev-guide b/src/doc/rustc-dev-guide
-Subproject 9198465b6ca8bed669df0cbb67c0e6d0b140803
+Subproject d1f03cbaa39d9164f5fe4b9b93762668142e0da
diff --git a/src/doc/rustc/src/codegen-options/index.md b/src/doc/rustc/src/codegen-options/index.md
index 05384117ac1..4f8c4c66f88 100644
--- a/src/doc/rustc/src/codegen-options/index.md
+++ b/src/doc/rustc/src/codegen-options/index.md
@@ -435,6 +435,10 @@ Equivalent to the "uppercase" `-fPIC` or `-fPIE` options in other compilers,
 depending on the produced crate types.  \
 This is the default model for majority of supported targets.
 
+- `pie` - position independent executable, relocatable code but without support for symbol
+interpositioning (replacing symbols by name using `LD_PRELOAD` and similar). Equivalent to the "uppercase" `-fPIE` option in other compilers. `pie`
+code cannot be linked into shared libraries (you'll get a linking error on attempt to do this).
+
 #### Special relocation models
 
 - `dynamic-no-pic` - relocatable external references, non-relocatable code.  \
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 611a4d08ab2..49fc93f3fea 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -1313,7 +1313,7 @@ impl Clean<Type> for hir::Ty<'_> {
         use rustc_hir::*;
 
         match self.kind {
-            TyKind::Never => Never,
+            TyKind::Never => Primitive(PrimitiveType::Never),
             TyKind::Ptr(ref m) => RawPointer(m.mutbl, box m.ty.clean(cx)),
             TyKind::Rptr(ref l, ref m) => {
                 // There are two times a `Fresh` lifetime can be created:
@@ -1402,7 +1402,7 @@ impl<'tcx> Clean<Type> for Ty<'tcx> {
         trace!("cleaning type: {:?}", self);
         let ty = normalize(cx, self).unwrap_or(self);
         match *ty.kind() {
-            ty::Never => Never,
+            ty::Never => Primitive(PrimitiveType::Never),
             ty::Bool => Primitive(PrimitiveType::Bool),
             ty::Char => Primitive(PrimitiveType::Char),
             ty::Int(int_ty) => Primitive(int_ty.into()),
diff --git a/src/librustdoc/clean/simplify.rs b/src/librustdoc/clean/simplify.rs
index d139b19f5dc..257af6ab910 100644
--- a/src/librustdoc/clean/simplify.rs
+++ b/src/librustdoc/clean/simplify.rs
@@ -11,8 +11,7 @@
 //! This module attempts to reconstruct the original where and/or parameter
 //! bounds by special casing scenarios such as these. Fun!
 
-use std::collections::BTreeMap;
-
+use rustc_data_structures::fx::FxIndexMap;
 use rustc_hir::def_id::DefId;
 use rustc_middle::ty;
 use rustc_span::Symbol;
@@ -23,8 +22,11 @@ use crate::clean::WherePredicate as WP;
 use crate::core::DocContext;
 
 crate fn where_clauses(cx: &DocContext<'_>, clauses: Vec<WP>) -> Vec<WP> {
-    // First, partition the where clause into its separate components
-    let mut params: BTreeMap<_, (Vec<_>, Vec<_>)> = BTreeMap::new();
+    // First, partition the where clause into its separate components.
+    //
+    // We use `FxIndexMap` so that the insertion order is preserved to prevent messing up to
+    // the order of the generated bounds.
+    let mut params: FxIndexMap<Symbol, (Vec<_>, Vec<_>)> = FxIndexMap::default();
     let mut lifetimes = Vec::new();
     let mut equalities = Vec::new();
     let mut tybounds = Vec::new();
diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
index 68a35e55c26..248ff339514 100644
--- a/src/librustdoc/clean/types.rs
+++ b/src/librustdoc/clean/types.rs
@@ -1396,7 +1396,6 @@ crate enum Type {
     Slice(Box<Type>),
     /// The `String` field is about the size or the constant representing the array's length.
     Array(Box<Type>, String),
-    Never,
     RawPointer(Mutability, Box<Type>),
     BorrowedRef {
         lifetime: Option<Lifetime>,
@@ -1462,7 +1461,6 @@ impl Type {
             }
             RawPointer(..) => Some(PrimitiveType::RawPointer),
             BareFunction(..) => Some(PrimitiveType::Fn),
-            Never => Some(PrimitiveType::Never),
             _ => None,
         }
     }
@@ -1550,7 +1548,6 @@ impl Type {
                 }
             }
             BareFunction(..) => PrimitiveType::Fn,
-            Never => PrimitiveType::Never,
             Slice(..) => PrimitiveType::Slice,
             Array(..) => PrimitiveType::Array,
             RawPointer(..) => PrimitiveType::RawPointer,
diff --git a/src/librustdoc/core.rs b/src/librustdoc/core.rs
index ddbe68762ee..074744b3d11 100644
--- a/src/librustdoc/core.rs
+++ b/src/librustdoc/core.rs
@@ -25,6 +25,7 @@ use rustc_span::symbol::sym;
 use rustc_span::Span;
 
 use std::cell::RefCell;
+use std::lazy::SyncLazy;
 use std::mem;
 use std::rc::Rc;
 
@@ -271,9 +272,8 @@ crate fn create_config(
             providers.typeck_item_bodies = |_, _| {};
             // hack so that `used_trait_imports` won't try to call typeck
             providers.used_trait_imports = |_, _| {
-                lazy_static! {
-                    static ref EMPTY_SET: FxHashSet<LocalDefId> = FxHashSet::default();
-                }
+                static EMPTY_SET: SyncLazy<FxHashSet<LocalDefId>> =
+                    SyncLazy::new(FxHashSet::default);
                 &EMPTY_SET
             };
             // In case typeck does end up being called, don't ICE in case there were name resolution errors
diff --git a/src/librustdoc/html/format.rs b/src/librustdoc/html/format.rs
index d11781581a8..bcd78b2adc0 100644
--- a/src/librustdoc/html/format.rs
+++ b/src/librustdoc/html/format.rs
@@ -761,6 +761,9 @@ fn fmt_type<'cx>(
             fmt::Display::fmt(&tybounds(bounds, lt, cx), f)
         }
         clean::Infer => write!(f, "_"),
+        clean::Primitive(clean::PrimitiveType::Never) => {
+            primitive_link(f, PrimitiveType::Never, "!", cx)
+        }
         clean::Primitive(prim) => primitive_link(f, prim, &*prim.as_sym().as_str(), cx),
         clean::BareFunction(ref decl) => {
             if f.alternate() {
@@ -819,7 +822,6 @@ fn fmt_type<'cx>(
                 primitive_link(f, PrimitiveType::Array, &format!("; {}]", Escape(n)), cx)
             }
         }
-        clean::Never => primitive_link(f, PrimitiveType::Never, "!", cx),
         clean::RawPointer(m, ref t) => {
             let m = match m {
                 hir::Mutability::Mut => "mut",
diff --git a/src/librustdoc/html/highlight.rs b/src/librustdoc/html/highlight.rs
index ece3ee640e2..43d1b8f794c 100644
--- a/src/librustdoc/html/highlight.rs
+++ b/src/librustdoc/html/highlight.rs
@@ -9,8 +9,8 @@ use crate::clean::PrimitiveType;
 use crate::html::escape::Escape;
 use crate::html::render::Context;
 
+use std::collections::VecDeque;
 use std::fmt::{Display, Write};
-use std::iter::Peekable;
 
 use rustc_lexer::{LiteralKind, TokenKind};
 use rustc_span::edition::Edition;
@@ -201,10 +201,57 @@ fn get_real_ident_class(text: &str, edition: Edition, allow_path_keywords: bool)
     })
 }
 
+/// This iterator comes from the same idea than "Peekable" except that it allows to "peek" more than
+/// just the next item by using `peek_next`. The `peek` method always returns the next item after
+/// the current one whereas `peek_next` will return the next item after the last one peeked.
+///
+/// You can use both `peek` and `peek_next` at the same time without problem.
+struct PeekIter<'a> {
+    stored: VecDeque<(TokenKind, &'a str)>,
+    /// This position is reinitialized when using `next`. It is used in `peek_next`.
+    peek_pos: usize,
+    iter: TokenIter<'a>,
+}
+
+impl PeekIter<'a> {
+    fn new(iter: TokenIter<'a>) -> Self {
+        Self { stored: VecDeque::new(), peek_pos: 0, iter }
+    }
+    /// Returns the next item after the current one. It doesn't interfer with `peek_next` output.
+    fn peek(&mut self) -> Option<&(TokenKind, &'a str)> {
+        if self.stored.is_empty() {
+            if let Some(next) = self.iter.next() {
+                self.stored.push_back(next);
+            }
+        }
+        self.stored.front()
+    }
+    /// Returns the next item after the last one peeked. It doesn't interfer with `peek` output.
+    fn peek_next(&mut self) -> Option<&(TokenKind, &'a str)> {
+        self.peek_pos += 1;
+        if self.peek_pos - 1 < self.stored.len() {
+            self.stored.get(self.peek_pos - 1)
+        } else if let Some(next) = self.iter.next() {
+            self.stored.push_back(next);
+            self.stored.back()
+        } else {
+            None
+        }
+    }
+}
+
+impl Iterator for PeekIter<'a> {
+    type Item = (TokenKind, &'a str);
+    fn next(&mut self) -> Option<Self::Item> {
+        self.peek_pos = 0;
+        if let Some(first) = self.stored.pop_front() { Some(first) } else { self.iter.next() }
+    }
+}
+
 /// Processes program tokens, classifying strings of text by highlighting
 /// category (`Class`).
 struct Classifier<'a> {
-    tokens: Peekable<TokenIter<'a>>,
+    tokens: PeekIter<'a>,
     in_attribute: bool,
     in_macro: bool,
     in_macro_nonterminal: bool,
@@ -218,7 +265,7 @@ impl<'a> Classifier<'a> {
     /// Takes as argument the source code to HTML-ify, the rust edition to use and the source code
     /// file span which will be used later on by the `span_correspondance_map`.
     fn new(src: &str, edition: Edition, file_span: Span) -> Classifier<'_> {
-        let tokens = TokenIter { src }.peekable();
+        let tokens = PeekIter::new(TokenIter { src });
         Classifier {
             tokens,
             in_attribute: false,
@@ -369,7 +416,7 @@ impl<'a> Classifier<'a> {
             // Assume that '&' or '*' is the reference or dereference operator
             // or a reference or pointer type. Unless, of course, it looks like
             // a logical and or a multiplication operator: `&&` or `* `.
-            TokenKind::Star => match lookahead {
+            TokenKind::Star => match self.peek() {
                 Some(TokenKind::Whitespace) => Class::Op,
                 _ => Class::RefKeyWord,
             },
@@ -480,6 +527,9 @@ impl<'a> Classifier<'a> {
                 None => match text {
                     "Option" | "Result" => Class::PreludeTy,
                     "Some" | "None" | "Ok" | "Err" => Class::PreludeVal,
+                    // "union" is a weak keyword and is only considered as a keyword when declaring
+                    // a union type.
+                    "union" if self.check_if_is_union_keyword() => Class::KeyWord,
                     _ if self.in_macro_nonterminal => {
                         self.in_macro_nonterminal = false;
                         Class::MacroNonTerminal
@@ -500,7 +550,17 @@ impl<'a> Classifier<'a> {
     }
 
     fn peek(&mut self) -> Option<TokenKind> {
-        self.tokens.peek().map(|(toke_kind, _text)| *toke_kind)
+        self.tokens.peek().map(|(token_kind, _text)| *token_kind)
+    }
+
+    fn check_if_is_union_keyword(&mut self) -> bool {
+        while let Some(kind) = self.tokens.peek_next().map(|(token_kind, _text)| token_kind) {
+            if *kind == TokenKind::Whitespace {
+                continue;
+            }
+            return *kind == TokenKind::Ident;
+        }
+        false
     }
 }
 
diff --git a/src/librustdoc/html/highlight/fixtures/union.html b/src/librustdoc/html/highlight/fixtures/union.html
new file mode 100644
index 00000000000..c0acf31a05d
--- /dev/null
+++ b/src/librustdoc/html/highlight/fixtures/union.html
@@ -0,0 +1,8 @@
+<span class="kw">union</span> <span class="ident">Foo</span> {
+    <span class="ident">i</span>: <span class="ident">i8</span>,
+    <span class="ident">u</span>: <span class="ident">i8</span>,
+}
+
+<span class="kw">fn</span> <span class="ident">main</span>() {
+    <span class="kw">let</span> <span class="ident">union</span> <span class="op">=</span> <span class="number">0</span>;
+}
diff --git a/src/librustdoc/html/highlight/fixtures/union.rs b/src/librustdoc/html/highlight/fixtures/union.rs
new file mode 100644
index 00000000000..269ee115d3f
--- /dev/null
+++ b/src/librustdoc/html/highlight/fixtures/union.rs
@@ -0,0 +1,8 @@
+union Foo {
+    i: i8,
+    u: i8,
+}
+
+fn main() {
+    let union = 0;
+}
diff --git a/src/librustdoc/html/highlight/tests.rs b/src/librustdoc/html/highlight/tests.rs
index 68592ae96c1..450bbfea1ea 100644
--- a/src/librustdoc/html/highlight/tests.rs
+++ b/src/librustdoc/html/highlight/tests.rs
@@ -54,3 +54,13 @@ let y = Self::whatever;";
         expect_file!["fixtures/highlight.html"].assert_eq(&html.into_inner());
     });
 }
+
+#[test]
+fn test_union_highlighting() {
+    create_default_session_globals_then(|| {
+        let src = include_str!("fixtures/union.rs");
+        let mut html = Buffer::new();
+        write_code(&mut html, src, Edition::Edition2018, None);
+        expect_file!["fixtures/union.html"].assert_eq(&html.into_inner());
+    });
+}
diff --git a/src/librustdoc/html/render/cache.rs b/src/librustdoc/html/render/cache.rs
index 1c083522bea..edd1d8b98fc 100644
--- a/src/librustdoc/html/render/cache.rs
+++ b/src/librustdoc/html/render/cache.rs
@@ -244,7 +244,6 @@ fn get_index_type_name(clean_type: &clean::Type, accept_generic: bool) -> Option
         | clean::Tuple(_)
         | clean::Slice(_)
         | clean::Array(_, _)
-        | clean::Never
         | clean::RawPointer(_, _)
         | clean::QPath { .. }
         | clean::Infer
diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs
index 1f27357f6c6..5045a99800a 100644
--- a/src/librustdoc/html/render/mod.rs
+++ b/src/librustdoc/html/render/mod.rs
@@ -599,14 +599,14 @@ fn short_item_info(
     let mut extra_info = vec![];
     let error_codes = cx.shared.codes;
 
-    if let Some(Deprecation { note, since, is_since_rustc_version, suggestion: _ }) =
+    if let Some(depr @ Deprecation { note, since, is_since_rustc_version: _, suggestion: _ }) =
         item.deprecation(cx.tcx())
     {
         // We display deprecation messages for #[deprecated] and #[rustc_deprecated]
         // but only display the future-deprecation messages for #[rustc_deprecated].
         let mut message = if let Some(since) = since {
             let since = &since.as_str();
-            if !stability::deprecation_in_effect(is_since_rustc_version, Some(since)) {
+            if !stability::deprecation_in_effect(&depr) {
                 if *since == "TBD" {
                     String::from("Deprecating in a future Rust version")
                 } else {
diff --git a/src/librustdoc/html/render/print_item.rs b/src/librustdoc/html/render/print_item.rs
index 8888b42d948..fa0d211efe6 100644
--- a/src/librustdoc/html/render/print_item.rs
+++ b/src/librustdoc/html/render/print_item.rs
@@ -418,10 +418,7 @@ fn extra_info_tags(item: &clean::Item, parent: &clean::Item, tcx: TyCtxt<'_>) ->
     // The trailing space after each tag is to space it properly against the rest of the docs.
     if let Some(depr) = &item.deprecation(tcx) {
         let mut message = "Deprecated";
-        if !stability::deprecation_in_effect(
-            depr.is_since_rustc_version,
-            depr.since.map(|s| s.as_str()).as_deref(),
-        ) {
+        if !stability::deprecation_in_effect(depr) {
             message = "Deprecation planned";
         }
         tags += &tag_html("deprecated", "", message);
diff --git a/src/librustdoc/json/conversions.rs b/src/librustdoc/json/conversions.rs
index fda90703057..ea81b041c3b 100644
--- a/src/librustdoc/json/conversions.rs
+++ b/src/librustdoc/json/conversions.rs
@@ -417,13 +417,13 @@ impl FromWithTcx<clean::Type> for Type {
                 }
             }
             Generic(s) => Type::Generic(s.to_string()),
+            Primitive(clean::PrimitiveType::Never) => Type::Never,
             Primitive(p) => Type::Primitive(p.as_sym().to_string()),
             BareFunction(f) => Type::FunctionPointer(Box::new((*f).into_tcx(tcx))),
             Tuple(t) => Type::Tuple(t.into_iter().map(|x| x.into_tcx(tcx)).collect()),
             Slice(t) => Type::Slice(Box::new((*t).into_tcx(tcx))),
             Array(t, s) => Type::Array { type_: Box::new((*t).into_tcx(tcx)), len: s },
             ImplTrait(g) => Type::ImplTrait(g.into_iter().map(|x| x.into_tcx(tcx)).collect()),
-            Never => Type::Never,
             Infer => Type::Infer,
             RawPointer(mutability, type_) => Type::RawPointer {
                 mutable: mutability == ast::Mutability::Mut,
diff --git a/src/librustdoc/json/mod.rs b/src/librustdoc/json/mod.rs
index 5089cc30a1e..915a9fd2b89 100644
--- a/src/librustdoc/json/mod.rs
+++ b/src/librustdoc/json/mod.rs
@@ -169,6 +169,8 @@ impl<'tcx> FormatRenderer<'tcx> for JsonRenderer<'tcx> {
                 s.impls = self.get_impls(id.expect_def_id())
             } else if let types::ItemEnum::Enum(ref mut e) = new_item.inner {
                 e.impls = self.get_impls(id.expect_def_id())
+            } else if let types::ItemEnum::Union(ref mut u) = new_item.inner {
+                u.impls = self.get_impls(id.expect_def_id())
             }
             let removed = self.index.borrow_mut().insert(from_item_id(id), new_item.clone());
 
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index 5cfd21046f5..efc8e31498a 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -19,8 +19,6 @@
 #![warn(rustc::internal)]
 
 #[macro_use]
-extern crate lazy_static;
-#[macro_use]
 extern crate tracing;
 
 // N.B. these need `extern crate` even in 2018 edition
diff --git a/src/llvm-project b/src/llvm-project
-Subproject cba558df777a045b5657d56c29944e9e8fd3a77
+Subproject 522c3e3d9c097b53ede7682cc28544b461597b2
diff --git a/src/test/assembly/pic-relocation-model.rs b/src/test/assembly/pic-relocation-model.rs
new file mode 100644
index 00000000000..72471ffcdb0
--- /dev/null
+++ b/src/test/assembly/pic-relocation-model.rs
@@ -0,0 +1,35 @@
+// revisions: x64
+// assembly-output: emit-asm
+// [x64] compile-flags: --target x86_64-unknown-linux-gnu -Crelocation-model=pic
+// [x64] needs-llvm-components: x86
+
+
+#![feature(no_core, lang_items)]
+#![no_core]
+#![crate_type="rlib"]
+
+#[lang = "sized"]
+trait Sized {}
+#[lang = "copy"]
+trait Copy {}
+
+// CHECK-LABEL: call_other_fn:
+// CHECK:       {{(jmpq|callq)}} *other_fn@GOTPCREL(%rip)
+#[no_mangle]
+pub fn call_other_fn() -> u8 {
+    unsafe {
+        other_fn()
+    }
+}
+
+// CHECK-LABEL: other_fn:
+// CHECK:       callq *foreign_fn@GOTPCREL(%rip)
+#[no_mangle]
+#[inline(never)]
+pub fn other_fn() -> u8 {
+    unsafe {
+        foreign_fn()
+    }
+}
+
+extern "C" {fn foreign_fn() -> u8;}
diff --git a/src/test/assembly/pie-relocation-model.rs b/src/test/assembly/pie-relocation-model.rs
new file mode 100644
index 00000000000..e40797e038d
--- /dev/null
+++ b/src/test/assembly/pie-relocation-model.rs
@@ -0,0 +1,38 @@
+// revisions: x64
+// assembly-output: emit-asm
+// [x64] compile-flags: --target x86_64-unknown-linux-gnu -Crelocation-model=pie
+// [x64] needs-llvm-components: x86
+
+
+#![feature(no_core, lang_items)]
+#![no_core]
+#![crate_type="rlib"]
+
+#[lang = "sized"]
+trait Sized {}
+#[lang = "copy"]
+trait Copy {}
+
+// CHECK-LABEL: call_other_fn:
+// With PIE local functions are called "directly".
+// CHECK:       {{(jmp|callq)}} other_fn
+#[no_mangle]
+pub fn call_other_fn() -> u8 {
+    unsafe {
+        other_fn()
+    }
+}
+
+// CHECK-LABEL: other_fn:
+// External functions are still called through GOT, since we don't know if the symbol
+// is defined in the binary or in the shared library.
+// CHECK:       callq *foreign_fn@GOTPCREL(%rip)
+#[no_mangle]
+#[inline(never)]
+pub fn other_fn() -> u8 {
+    unsafe {
+        foreign_fn()
+    }
+}
+
+extern "C" {fn foreign_fn() -> u8;}
diff --git a/src/test/codegen/pic-relocation-model.rs b/src/test/codegen/pic-relocation-model.rs
new file mode 100644
index 00000000000..6e1d5a6c3f2
--- /dev/null
+++ b/src/test/codegen/pic-relocation-model.rs
@@ -0,0 +1,16 @@
+// compile-flags: -C relocation-model=pic
+
+#![crate_type = "rlib"]
+
+// CHECK: define i8 @call_foreign_fn()
+#[no_mangle]
+pub fn call_foreign_fn() -> u8 {
+    unsafe {
+        foreign_fn()
+    }
+}
+
+// CHECK: declare zeroext i8 @foreign_fn()
+extern "C" {fn foreign_fn() -> u8;}
+
+// CHECK: !{i32 7, !"PIC Level", i32 2}
diff --git a/src/test/codegen/pie-relocation-model.rs b/src/test/codegen/pie-relocation-model.rs
new file mode 100644
index 00000000000..a843202a94f
--- /dev/null
+++ b/src/test/codegen/pie-relocation-model.rs
@@ -0,0 +1,22 @@
+// compile-flags: -C relocation-model=pie
+// only-x86_64-unknown-linux-gnu
+
+#![crate_type = "rlib"]
+
+// With PIE we know local functions cannot be interpositioned, we can mark them
+// as dso_local.
+// CHECK: define dso_local i8 @call_foreign_fn()
+#[no_mangle]
+pub fn call_foreign_fn() -> u8 {
+    unsafe {
+        foreign_fn()
+    }
+}
+
+// External functions are still marked as non-dso_local, since we don't know if the symbol
+// is defined in the binary or in the shared library.
+// CHECK: declare zeroext i8 @foreign_fn()
+extern "C" {fn foreign_fn() -> u8;}
+
+// CHECK: !{i32 7, !"PIC Level", i32 2}
+// CHECK: !{i32 7, !"PIE Level", i32 2}
diff --git a/src/test/mir-opt/const_promotion_extern_static.BAR-promoted[0].SimplifyCfg-elaborate-drops.after.mir b/src/test/mir-opt/const_promotion_extern_static.BAR-promoted[0].SimplifyCfg-elaborate-drops.after.mir
index a64c960b9f7..bec0fa9c049 100644
--- a/src/test/mir-opt/const_promotion_extern_static.BAR-promoted[0].SimplifyCfg-elaborate-drops.after.mir
+++ b/src/test/mir-opt/const_promotion_extern_static.BAR-promoted[0].SimplifyCfg-elaborate-drops.after.mir
@@ -1,7 +1,7 @@
 // MIR for `BAR::promoted[0]` after SimplifyCfg-elaborate-drops
 
 promoted[0] in BAR: &[&i32; 1] = {
-    let mut _0: &[&i32; 1];              // return place in scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:35
+    let mut _0: &[&i32; 1];              // return place in scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:44
     let mut _1: [&i32; 1];               // in scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:35
     let mut _2: &i32;                    // in scope 0 at $DIR/const-promotion-extern-static.rs:9:32: 9:34
     let mut _3: &i32;                    // in scope 0 at $DIR/const-promotion-extern-static.rs:9:33: 9:34
@@ -16,8 +16,8 @@ promoted[0] in BAR: &[&i32; 1] = {
                                          // + literal: Const { ty: &i32, val: Value(Scalar(alloc1)) }
         _2 = &(*_3);                     // scope 0 at $DIR/const-promotion-extern-static.rs:9:32: 9:34
         _1 = [move _2];                  // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:35
-        _0 = &_1;                        // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:35
-        return;                          // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:35
+        _0 = &_1;                        // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:44
+        return;                          // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:44
     }
 }
 
diff --git a/src/test/mir-opt/const_promotion_extern_static.BAR.PromoteTemps.diff b/src/test/mir-opt/const_promotion_extern_static.BAR.PromoteTemps.diff
index 49d0a7ff455..bdd62f1029f 100644
--- a/src/test/mir-opt/const_promotion_extern_static.BAR.PromoteTemps.diff
+++ b/src/test/mir-opt/const_promotion_extern_static.BAR.PromoteTemps.diff
@@ -3,21 +3,21 @@
   
   static mut BAR: *const &i32 = {
       let mut _0: *const &i32;             // return place in scope 0 at $DIR/const-promotion-extern-static.rs:9:17: 9:28
-      let mut _1: &[&i32];                 // in scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:35
-      let mut _2: &[&i32; 1];              // in scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:35
+      let mut _1: &[&i32];                 // in scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:44
+      let mut _2: &[&i32; 1];              // in scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:44
       let _3: [&i32; 1];                   // in scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:35
       let mut _4: &i32;                    // in scope 0 at $DIR/const-promotion-extern-static.rs:9:32: 9:34
       let _5: &i32;                        // in scope 0 at $DIR/const-promotion-extern-static.rs:9:33: 9:34
-+     let mut _6: &[&i32; 1];              // in scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:35
++     let mut _6: &[&i32; 1];              // in scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:44
   
       bb0: {
-          StorageLive(_1);                 // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:35
-          StorageLive(_2);                 // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:35
+          StorageLive(_1);                 // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:44
+          StorageLive(_2);                 // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:44
 -         StorageLive(_3);                 // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:35
 -         StorageLive(_4);                 // scope 0 at $DIR/const-promotion-extern-static.rs:9:32: 9:34
 -         StorageLive(_5);                 // scope 0 at $DIR/const-promotion-extern-static.rs:9:33: 9:34
 -         _5 = const {alloc1: &i32};       // scope 0 at $DIR/const-promotion-extern-static.rs:9:33: 9:34
-+         _6 = const BAR::promoted[0];     // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:35
++         _6 = const BAR::promoted[0];     // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:44
                                            // ty::Const
 -                                          // + ty: &i32
 -                                          // + val: Value(Scalar(alloc1))
@@ -28,11 +28,11 @@
 -                                          // + literal: Const { ty: &i32, val: Value(Scalar(alloc1)) }
 -         _4 = &(*_5);                     // scope 0 at $DIR/const-promotion-extern-static.rs:9:32: 9:34
 -         _3 = [move _4];                  // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:35
--         _2 = &_3;                        // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:35
-+                                          // + span: $DIR/const-promotion-extern-static.rs:9:31: 9:35
+-         _2 = &_3;                        // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:44
++                                          // + span: $DIR/const-promotion-extern-static.rs:9:31: 9:44
 +                                          // + literal: Const { ty: &[&i32; 1], val: Unevaluated(Unevaluated { def: WithOptConstParam { did: DefId(0:6 ~ const_promotion_extern_static[55e6]::BAR), const_param_did: None }, substs_: Some([]), promoted: Some(promoted[0]) }) }
-+         _2 = &(*_6);                     // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:35
-          _1 = move _2 as &[&i32] (Pointer(Unsize)); // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:35
++         _2 = &(*_6);                     // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:44
+          _1 = move _2 as &[&i32] (Pointer(Unsize)); // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:44
 -         StorageDead(_4);                 // scope 0 at $DIR/const-promotion-extern-static.rs:9:34: 9:35
           StorageDead(_2);                 // scope 0 at $DIR/const-promotion-extern-static.rs:9:34: 9:35
           _0 = core::slice::<impl [&i32]>::as_ptr(move _1) -> [return: bb1, unwind: bb2]; // scope 0 at $DIR/const-promotion-extern-static.rs:9:31: 9:44
diff --git a/src/test/mir-opt/const_promotion_extern_static.FOO-promoted[0].SimplifyCfg-elaborate-drops.after.mir b/src/test/mir-opt/const_promotion_extern_static.FOO-promoted[0].SimplifyCfg-elaborate-drops.after.mir
index 8b3c5d332f2..c01b31525b6 100644
--- a/src/test/mir-opt/const_promotion_extern_static.FOO-promoted[0].SimplifyCfg-elaborate-drops.after.mir
+++ b/src/test/mir-opt/const_promotion_extern_static.FOO-promoted[0].SimplifyCfg-elaborate-drops.after.mir
@@ -1,7 +1,7 @@
 // MIR for `FOO::promoted[0]` after SimplifyCfg-elaborate-drops
 
 promoted[0] in FOO: &[&i32; 1] = {
-    let mut _0: &[&i32; 1];              // return place in scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
+    let mut _0: &[&i32; 1];              // return place in scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:55
     let mut _1: [&i32; 1];               // in scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
     let mut _2: &i32;                    // in scope 0 at $DIR/const-promotion-extern-static.rs:13:32: 13:45
     let mut _3: *const i32;              // in scope 0 at $DIR/const-promotion-extern-static.rs:13:42: 13:43
@@ -16,8 +16,8 @@ promoted[0] in FOO: &[&i32; 1] = {
                                          // + literal: Const { ty: *const i32, val: Value(Scalar(alloc3)) }
         _2 = &(*_3);                     // scope 0 at $DIR/const-promotion-extern-static.rs:13:41: 13:43
         _1 = [move _2];                  // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
-        _0 = &_1;                        // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
-        return;                          // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
+        _0 = &_1;                        // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:55
+        return;                          // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:55
     }
 }
 
diff --git a/src/test/mir-opt/const_promotion_extern_static.FOO.PromoteTemps.diff b/src/test/mir-opt/const_promotion_extern_static.FOO.PromoteTemps.diff
index f2504ae880e..94b337806af 100644
--- a/src/test/mir-opt/const_promotion_extern_static.FOO.PromoteTemps.diff
+++ b/src/test/mir-opt/const_promotion_extern_static.FOO.PromoteTemps.diff
@@ -3,23 +3,23 @@
   
   static mut FOO: *const &i32 = {
       let mut _0: *const &i32;             // return place in scope 0 at $DIR/const-promotion-extern-static.rs:13:17: 13:28
-      let mut _1: &[&i32];                 // in scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
-      let mut _2: &[&i32; 1];              // in scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
+      let mut _1: &[&i32];                 // in scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:55
+      let mut _2: &[&i32; 1];              // in scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:55
       let _3: [&i32; 1];                   // in scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
       let mut _4: &i32;                    // in scope 0 at $DIR/const-promotion-extern-static.rs:13:32: 13:45
       let _5: *const i32;                  // in scope 0 at $DIR/const-promotion-extern-static.rs:13:42: 13:43
-+     let mut _6: &[&i32; 1];              // in scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
++     let mut _6: &[&i32; 1];              // in scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:55
       scope 1 {
       }
   
       bb0: {
-          StorageLive(_1);                 // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
-          StorageLive(_2);                 // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
+          StorageLive(_1);                 // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:55
+          StorageLive(_2);                 // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:55
 -         StorageLive(_3);                 // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
 -         StorageLive(_4);                 // scope 0 at $DIR/const-promotion-extern-static.rs:13:32: 13:45
 -         StorageLive(_5);                 // scope 1 at $DIR/const-promotion-extern-static.rs:13:42: 13:43
 -         _5 = const {alloc3: *const i32}; // scope 1 at $DIR/const-promotion-extern-static.rs:13:42: 13:43
-+         _6 = const FOO::promoted[0];     // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
++         _6 = const FOO::promoted[0];     // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:55
                                            // ty::Const
 -                                          // + ty: *const i32
 -                                          // + val: Value(Scalar(alloc3))
@@ -30,11 +30,11 @@
 -                                          // + literal: Const { ty: *const i32, val: Value(Scalar(alloc3)) }
 -         _4 = &(*_5);                     // scope 1 at $DIR/const-promotion-extern-static.rs:13:41: 13:43
 -         _3 = [move _4];                  // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
--         _2 = &_3;                        // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
-+                                          // + span: $DIR/const-promotion-extern-static.rs:13:31: 13:46
+-         _2 = &_3;                        // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:55
++                                          // + span: $DIR/const-promotion-extern-static.rs:13:31: 13:55
 +                                          // + literal: Const { ty: &[&i32; 1], val: Unevaluated(Unevaluated { def: WithOptConstParam { did: DefId(0:7 ~ const_promotion_extern_static[55e6]::FOO), const_param_did: None }, substs_: Some([]), promoted: Some(promoted[0]) }) }
-+         _2 = &(*_6);                     // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
-          _1 = move _2 as &[&i32] (Pointer(Unsize)); // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:46
++         _2 = &(*_6);                     // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:55
+          _1 = move _2 as &[&i32] (Pointer(Unsize)); // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:55
 -         StorageDead(_4);                 // scope 0 at $DIR/const-promotion-extern-static.rs:13:45: 13:46
           StorageDead(_2);                 // scope 0 at $DIR/const-promotion-extern-static.rs:13:45: 13:46
           _0 = core::slice::<impl [&i32]>::as_ptr(move _1) -> [return: bb1, unwind: bb2]; // scope 0 at $DIR/const-promotion-extern-static.rs:13:31: 13:55
diff --git a/src/test/mir-opt/deduplicate_blocks.is_line_doc_comment_2.DeduplicateBlocks.diff b/src/test/mir-opt/deduplicate_blocks.is_line_doc_comment_2.DeduplicateBlocks.diff
index 48a37a8496c..7695afded3d 100644
--- a/src/test/mir-opt/deduplicate_blocks.is_line_doc_comment_2.DeduplicateBlocks.diff
+++ b/src/test/mir-opt/deduplicate_blocks.is_line_doc_comment_2.DeduplicateBlocks.diff
@@ -5,7 +5,7 @@
       debug s => _1;                       // in scope 0 at $DIR/deduplicate_blocks.rs:2:36: 2:37
       let mut _0: bool;                    // return place in scope 0 at $DIR/deduplicate_blocks.rs:2:48: 2:52
       let mut _2: &[u8];                   // in scope 0 at $DIR/deduplicate_blocks.rs:3:11: 3:23
-      let mut _3: &str;                    // in scope 0 at $DIR/deduplicate_blocks.rs:3:11: 3:12
+      let mut _3: &str;                    // in scope 0 at $DIR/deduplicate_blocks.rs:3:11: 3:23
       let mut _4: usize;                   // in scope 0 at $DIR/deduplicate_blocks.rs:5:9: 5:31
       let mut _5: bool;                    // in scope 0 at $DIR/deduplicate_blocks.rs:5:9: 5:31
       let mut _6: usize;                   // in scope 0 at $DIR/deduplicate_blocks.rs:4:9: 4:37
@@ -19,8 +19,8 @@
   
       bb0: {
           StorageLive(_2);                 // scope 0 at $DIR/deduplicate_blocks.rs:3:11: 3:23
-          StorageLive(_3);                 // scope 0 at $DIR/deduplicate_blocks.rs:3:11: 3:12
-          _3 = _1;                         // scope 0 at $DIR/deduplicate_blocks.rs:3:11: 3:12
+          StorageLive(_3);                 // scope 0 at $DIR/deduplicate_blocks.rs:3:11: 3:23
+          _3 = _1;                         // scope 0 at $DIR/deduplicate_blocks.rs:3:11: 3:23
           StorageLive(_8);                 // scope 2 at $DIR/deduplicate_blocks.rs:3:11: 3:23
           _8 = _3;                         // scope 2 at $DIR/deduplicate_blocks.rs:3:11: 3:23
 -         _2 = transmute::<&str, &[u8]>(move _8) -> bb14; // scope 2 at $DIR/deduplicate_blocks.rs:3:11: 3:23
diff --git a/src/test/mir-opt/funky_arms.float_to_exponential_common.ConstProp.diff b/src/test/mir-opt/funky_arms.float_to_exponential_common.ConstProp.diff
index fd29e14a041..000bc634325 100644
--- a/src/test/mir-opt/funky_arms.float_to_exponential_common.ConstProp.diff
+++ b/src/test/mir-opt/funky_arms.float_to_exponential_common.ConstProp.diff
@@ -7,9 +7,9 @@
       debug upper => _3;                   // in scope 0 at $DIR/funky_arms.rs:11:69: 11:74
       let mut _0: std::result::Result<(), std::fmt::Error>; // return place in scope 0 at $DIR/funky_arms.rs:11:85: 11:91
       let _4: bool;                        // in scope 0 at $DIR/funky_arms.rs:15:9: 15:19
-      let mut _5: &std::fmt::Formatter;    // in scope 0 at $DIR/funky_arms.rs:15:22: 15:25
+      let mut _5: &std::fmt::Formatter;    // in scope 0 at $DIR/funky_arms.rs:15:22: 15:37
       let mut _7: std::option::Option<usize>; // in scope 0 at $DIR/funky_arms.rs:24:30: 24:45
-      let mut _8: &std::fmt::Formatter;    // in scope 0 at $DIR/funky_arms.rs:24:30: 24:33
+      let mut _8: &std::fmt::Formatter;    // in scope 0 at $DIR/funky_arms.rs:24:30: 24:45
       let mut _9: isize;                   // in scope 0 at $DIR/funky_arms.rs:24:12: 24:27
       let mut _11: &mut std::fmt::Formatter; // in scope 0 at $DIR/funky_arms.rs:26:43: 26:46
       let mut _12: &T;                     // in scope 0 at $DIR/funky_arms.rs:26:48: 26:51
@@ -36,8 +36,8 @@
   
       bb0: {
           StorageLive(_4);                 // scope 0 at $DIR/funky_arms.rs:15:9: 15:19
-          StorageLive(_5);                 // scope 0 at $DIR/funky_arms.rs:15:22: 15:25
-          _5 = &(*_1);                     // scope 0 at $DIR/funky_arms.rs:15:22: 15:25
+          StorageLive(_5);                 // scope 0 at $DIR/funky_arms.rs:15:22: 15:37
+          _5 = &(*_1);                     // scope 0 at $DIR/funky_arms.rs:15:22: 15:37
           _4 = Formatter::sign_plus(move _5) -> bb1; // scope 0 at $DIR/funky_arms.rs:15:22: 15:37
                                            // mir::Constant
                                            // + span: $DIR/funky_arms.rs:15:26: 15:35
@@ -62,8 +62,8 @@
   
       bb4: {
           StorageLive(_7);                 // scope 2 at $DIR/funky_arms.rs:24:30: 24:45
-          StorageLive(_8);                 // scope 2 at $DIR/funky_arms.rs:24:30: 24:33
-          _8 = &(*_1);                     // scope 2 at $DIR/funky_arms.rs:24:30: 24:33
+          StorageLive(_8);                 // scope 2 at $DIR/funky_arms.rs:24:30: 24:45
+          _8 = &(*_1);                     // scope 2 at $DIR/funky_arms.rs:24:30: 24:45
           _7 = Formatter::precision(move _8) -> bb5; // scope 2 at $DIR/funky_arms.rs:24:30: 24:45
                                            // mir::Constant
                                            // + span: $DIR/funky_arms.rs:24:34: 24:43
diff --git a/src/test/mir-opt/inline/inline_shims.clone.Inline.diff b/src/test/mir-opt/inline/inline_shims.clone.Inline.diff
index 3bdd4f4ff56..7379d5f219c 100644
--- a/src/test/mir-opt/inline/inline_shims.clone.Inline.diff
+++ b/src/test/mir-opt/inline/inline_shims.clone.Inline.diff
@@ -4,13 +4,13 @@
   fn clone(_1: fn(A, B)) -> fn(A, B) {
       debug f => _1;                       // in scope 0 at $DIR/inline-shims.rs:5:20: 5:21
       let mut _0: fn(A, B);                // return place in scope 0 at $DIR/inline-shims.rs:5:36: 5:44
-      let mut _2: &fn(A, B);               // in scope 0 at $DIR/inline-shims.rs:6:5: 6:6
+      let mut _2: &fn(A, B);               // in scope 0 at $DIR/inline-shims.rs:6:5: 6:14
 +     scope 1 (inlined <fn(A, B) as Clone>::clone - shim(fn(A, B))) { // at $DIR/inline-shims.rs:6:5: 6:14
 +     }
   
       bb0: {
-          StorageLive(_2);                 // scope 0 at $DIR/inline-shims.rs:6:5: 6:6
-          _2 = &_1;                        // scope 0 at $DIR/inline-shims.rs:6:5: 6:6
+          StorageLive(_2);                 // scope 0 at $DIR/inline-shims.rs:6:5: 6:14
+          _2 = &_1;                        // scope 0 at $DIR/inline-shims.rs:6:5: 6:14
 -         _0 = <fn(A, B) as Clone>::clone(move _2) -> bb1; // scope 0 at $DIR/inline-shims.rs:6:5: 6:14
 -                                          // mir::Constant
 -                                          // + span: $DIR/inline-shims.rs:6:7: 6:12
diff --git a/src/test/mir-opt/inline/inline_trait_method.test.Inline.after.mir b/src/test/mir-opt/inline/inline_trait_method.test.Inline.after.mir
index eada5ac1347..0be979901ac 100644
--- a/src/test/mir-opt/inline/inline_trait_method.test.Inline.after.mir
+++ b/src/test/mir-opt/inline/inline_trait_method.test.Inline.after.mir
@@ -3,11 +3,11 @@
 fn test(_1: &dyn X) -> u32 {
     debug x => _1;                       // in scope 0 at $DIR/inline-trait-method.rs:8:9: 8:10
     let mut _0: u32;                     // return place in scope 0 at $DIR/inline-trait-method.rs:8:23: 8:26
-    let mut _2: &dyn X;                  // in scope 0 at $DIR/inline-trait-method.rs:9:5: 9:6
+    let mut _2: &dyn X;                  // in scope 0 at $DIR/inline-trait-method.rs:9:5: 9:10
 
     bb0: {
-        StorageLive(_2);                 // scope 0 at $DIR/inline-trait-method.rs:9:5: 9:6
-        _2 = &(*_1);                     // scope 0 at $DIR/inline-trait-method.rs:9:5: 9:6
+        StorageLive(_2);                 // scope 0 at $DIR/inline-trait-method.rs:9:5: 9:10
+        _2 = &(*_1);                     // scope 0 at $DIR/inline-trait-method.rs:9:5: 9:10
         _0 = <dyn X as X>::y(move _2) -> bb1; // scope 0 at $DIR/inline-trait-method.rs:9:5: 9:10
                                          // mir::Constant
                                          // + span: $DIR/inline-trait-method.rs:9:7: 9:8
diff --git a/src/test/mir-opt/inline/issue_58867_inline_as_ref_as_mut.a.Inline.after.mir b/src/test/mir-opt/inline/issue_58867_inline_as_ref_as_mut.a.Inline.after.mir
index 651855f8024..1b5153daa8b 100644
--- a/src/test/mir-opt/inline/issue_58867_inline_as_ref_as_mut.a.Inline.after.mir
+++ b/src/test/mir-opt/inline/issue_58867_inline_as_ref_as_mut.a.Inline.after.mir
@@ -5,7 +5,7 @@ fn a(_1: &mut [T]) -> &mut [T] {
     let mut _0: &mut [T];                // return place in scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:2:29: 2:37
     let mut _2: &mut [T];                // in scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:3:5: 3:15
     let mut _3: &mut [T];                // in scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:3:5: 3:15
-    let mut _4: &mut [T];                // in scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:3:5: 3:6
+    let mut _4: &mut [T];                // in scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:3:5: 3:15
     scope 1 (inlined <[T] as AsMut<[T]>>::as_mut) { // at $DIR/issue-58867-inline-as-ref-as-mut.rs:3:5: 3:15
         debug self => _4;                // in scope 1 at $DIR/issue-58867-inline-as-ref-as-mut.rs:3:5: 3:15
         let mut _5: &mut [T];            // in scope 1 at $DIR/issue-58867-inline-as-ref-as-mut.rs:3:5: 3:15
@@ -14,8 +14,8 @@ fn a(_1: &mut [T]) -> &mut [T] {
     bb0: {
         StorageLive(_2);                 // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:3:5: 3:15
         StorageLive(_3);                 // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:3:5: 3:15
-        StorageLive(_4);                 // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:3:5: 3:6
-        _4 = &mut (*_1);                 // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:3:5: 3:6
+        StorageLive(_4);                 // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:3:5: 3:15
+        _4 = &mut (*_1);                 // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:3:5: 3:15
         StorageLive(_5);                 // scope 1 at $DIR/issue-58867-inline-as-ref-as-mut.rs:3:5: 3:15
         _5 = &mut (*_4);                 // scope 1 at $DIR/issue-58867-inline-as-ref-as-mut.rs:3:5: 3:15
         _3 = &mut (*_5);                 // scope 1 at $DIR/issue-58867-inline-as-ref-as-mut.rs:3:5: 3:15
diff --git a/src/test/mir-opt/inline/issue_58867_inline_as_ref_as_mut.b.Inline.after.mir b/src/test/mir-opt/inline/issue_58867_inline_as_ref_as_mut.b.Inline.after.mir
index c67ea7e00b7..257ddec780e 100644
--- a/src/test/mir-opt/inline/issue_58867_inline_as_ref_as_mut.b.Inline.after.mir
+++ b/src/test/mir-opt/inline/issue_58867_inline_as_ref_as_mut.b.Inline.after.mir
@@ -5,7 +5,7 @@ fn b(_1: &mut Box<T>) -> &mut T {
     let mut _0: &mut T;                  // return place in scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:7:32: 7:38
     let mut _2: &mut T;                  // in scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:8:5: 8:15
     let mut _3: &mut T;                  // in scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:8:5: 8:15
-    let mut _4: &mut std::boxed::Box<T>; // in scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:8:5: 8:6
+    let mut _4: &mut std::boxed::Box<T>; // in scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:8:5: 8:15
     scope 1 (inlined <Box<T> as AsMut<T>>::as_mut) { // at $DIR/issue-58867-inline-as-ref-as-mut.rs:8:5: 8:15
         debug self => _4;                // in scope 1 at $DIR/issue-58867-inline-as-ref-as-mut.rs:8:5: 8:15
         let mut _5: &mut T;              // in scope 1 at $DIR/issue-58867-inline-as-ref-as-mut.rs:8:5: 8:15
@@ -15,8 +15,8 @@ fn b(_1: &mut Box<T>) -> &mut T {
     bb0: {
         StorageLive(_2);                 // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:8:5: 8:15
         StorageLive(_3);                 // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:8:5: 8:15
-        StorageLive(_4);                 // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:8:5: 8:6
-        _4 = &mut (*_1);                 // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:8:5: 8:6
+        StorageLive(_4);                 // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:8:5: 8:15
+        _4 = &mut (*_1);                 // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:8:5: 8:15
         StorageLive(_5);                 // scope 1 at $DIR/issue-58867-inline-as-ref-as-mut.rs:8:5: 8:15
         StorageLive(_6);                 // scope 1 at $DIR/issue-58867-inline-as-ref-as-mut.rs:8:5: 8:15
         _6 = &mut (*(*_4));              // scope 1 at $DIR/issue-58867-inline-as-ref-as-mut.rs:8:5: 8:15
diff --git a/src/test/mir-opt/inline/issue_58867_inline_as_ref_as_mut.c.Inline.after.mir b/src/test/mir-opt/inline/issue_58867_inline_as_ref_as_mut.c.Inline.after.mir
index 16fae453ac9..9817e8cd5fa 100644
--- a/src/test/mir-opt/inline/issue_58867_inline_as_ref_as_mut.c.Inline.after.mir
+++ b/src/test/mir-opt/inline/issue_58867_inline_as_ref_as_mut.c.Inline.after.mir
@@ -4,15 +4,15 @@ fn c(_1: &[T]) -> &[T] {
     debug x => _1;                       // in scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:12:13: 12:14
     let mut _0: &[T];                    // return place in scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:12:25: 12:29
     let _2: &[T];                        // in scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:13:5: 13:15
-    let mut _3: &[T];                    // in scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:13:5: 13:6
+    let mut _3: &[T];                    // in scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:13:5: 13:15
     scope 1 (inlined <[T] as AsRef<[T]>>::as_ref) { // at $DIR/issue-58867-inline-as-ref-as-mut.rs:13:5: 13:15
         debug self => _3;                // in scope 1 at $DIR/issue-58867-inline-as-ref-as-mut.rs:13:5: 13:15
     }
 
     bb0: {
         StorageLive(_2);                 // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:13:5: 13:15
-        StorageLive(_3);                 // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:13:5: 13:6
-        _3 = &(*_1);                     // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:13:5: 13:6
+        StorageLive(_3);                 // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:13:5: 13:15
+        _3 = &(*_1);                     // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:13:5: 13:15
         _2 = _3;                         // scope 1 at $DIR/issue-58867-inline-as-ref-as-mut.rs:13:5: 13:15
         _0 = &(*_2);                     // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:13:5: 13:15
         StorageDead(_3);                 // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:13:14: 13:15
diff --git a/src/test/mir-opt/inline/issue_58867_inline_as_ref_as_mut.d.Inline.after.mir b/src/test/mir-opt/inline/issue_58867_inline_as_ref_as_mut.d.Inline.after.mir
index e9ca7095a43..e49c91581b3 100644
--- a/src/test/mir-opt/inline/issue_58867_inline_as_ref_as_mut.d.Inline.after.mir
+++ b/src/test/mir-opt/inline/issue_58867_inline_as_ref_as_mut.d.Inline.after.mir
@@ -4,15 +4,15 @@ fn d(_1: &Box<T>) -> &T {
     debug x => _1;                       // in scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:17:13: 17:14
     let mut _0: &T;                      // return place in scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:17:28: 17:30
     let _2: &T;                          // in scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:18:5: 18:15
-    let mut _3: &std::boxed::Box<T>;     // in scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:18:5: 18:6
+    let mut _3: &std::boxed::Box<T>;     // in scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:18:5: 18:15
     scope 1 (inlined <Box<T> as AsRef<T>>::as_ref) { // at $DIR/issue-58867-inline-as-ref-as-mut.rs:18:5: 18:15
         debug self => _3;                // in scope 1 at $DIR/issue-58867-inline-as-ref-as-mut.rs:18:5: 18:15
     }
 
     bb0: {
         StorageLive(_2);                 // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:18:5: 18:15
-        StorageLive(_3);                 // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:18:5: 18:6
-        _3 = &(*_1);                     // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:18:5: 18:6
+        StorageLive(_3);                 // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:18:5: 18:15
+        _3 = &(*_1);                     // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:18:5: 18:15
         _2 = &(*(*_3));                  // scope 1 at $DIR/issue-58867-inline-as-ref-as-mut.rs:18:5: 18:15
         _0 = &(*_2);                     // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:18:5: 18:15
         StorageDead(_3);                 // scope 0 at $DIR/issue-58867-inline-as-ref-as-mut.rs:18:14: 18:15
diff --git a/src/test/mir-opt/lower_slice_len.bound.LowerSliceLenCalls.diff b/src/test/mir-opt/lower_slice_len.bound.LowerSliceLenCalls.diff
index 25db3b98c25..13241d882f2 100644
--- a/src/test/mir-opt/lower_slice_len.bound.LowerSliceLenCalls.diff
+++ b/src/test/mir-opt/lower_slice_len.bound.LowerSliceLenCalls.diff
@@ -8,7 +8,7 @@
       let mut _3: bool;                    // in scope 0 at $DIR/lower_slice_len.rs:5:8: 5:27
       let mut _4: usize;                   // in scope 0 at $DIR/lower_slice_len.rs:5:8: 5:13
       let mut _5: usize;                   // in scope 0 at $DIR/lower_slice_len.rs:5:16: 5:27
-      let mut _6: &[u8];                   // in scope 0 at $DIR/lower_slice_len.rs:5:16: 5:21
+      let mut _6: &[u8];                   // in scope 0 at $DIR/lower_slice_len.rs:5:16: 5:27
       let _7: usize;                       // in scope 0 at $DIR/lower_slice_len.rs:6:15: 6:20
       let mut _8: usize;                   // in scope 0 at $DIR/lower_slice_len.rs:6:9: 6:21
       let mut _9: bool;                    // in scope 0 at $DIR/lower_slice_len.rs:6:9: 6:21
@@ -18,8 +18,8 @@
           StorageLive(_4);                 // scope 0 at $DIR/lower_slice_len.rs:5:8: 5:13
           _4 = _1;                         // scope 0 at $DIR/lower_slice_len.rs:5:8: 5:13
           StorageLive(_5);                 // scope 0 at $DIR/lower_slice_len.rs:5:16: 5:27
-          StorageLive(_6);                 // scope 0 at $DIR/lower_slice_len.rs:5:16: 5:21
-          _6 = &(*_2);                     // scope 0 at $DIR/lower_slice_len.rs:5:16: 5:21
+          StorageLive(_6);                 // scope 0 at $DIR/lower_slice_len.rs:5:16: 5:27
+          _6 = &(*_2);                     // scope 0 at $DIR/lower_slice_len.rs:5:16: 5:27
 -         _5 = core::slice::<impl [u8]>::len(move _6) -> bb1; // scope 0 at $DIR/lower_slice_len.rs:5:16: 5:27
 -                                          // mir::Constant
 -                                          // + span: $DIR/lower_slice_len.rs:5:22: 5:25
diff --git a/src/test/mir-opt/no_spurious_drop_after_call.main.ElaborateDrops.before.mir b/src/test/mir-opt/no_spurious_drop_after_call.main.ElaborateDrops.before.mir
index 7bdf7b6a648..5c55ee4b9bb 100644
--- a/src/test/mir-opt/no_spurious_drop_after_call.main.ElaborateDrops.before.mir
+++ b/src/test/mir-opt/no_spurious_drop_after_call.main.ElaborateDrops.before.mir
@@ -4,13 +4,13 @@ fn main() -> () {
     let mut _0: ();                      // return place in scope 0 at $DIR/no-spurious-drop-after-call.rs:8:11: 8:11
     let _1: ();                          // in scope 0 at $DIR/no-spurious-drop-after-call.rs:9:5: 9:35
     let mut _2: std::string::String;     // in scope 0 at $DIR/no-spurious-drop-after-call.rs:9:20: 9:34
-    let mut _3: &str;                    // in scope 0 at $DIR/no-spurious-drop-after-call.rs:9:20: 9:22
+    let mut _3: &str;                    // in scope 0 at $DIR/no-spurious-drop-after-call.rs:9:20: 9:34
     let _4: &str;                        // in scope 0 at $DIR/no-spurious-drop-after-call.rs:9:20: 9:22
 
     bb0: {
         StorageLive(_1);                 // scope 0 at $DIR/no-spurious-drop-after-call.rs:9:5: 9:35
         StorageLive(_2);                 // scope 0 at $DIR/no-spurious-drop-after-call.rs:9:20: 9:34
-        StorageLive(_3);                 // scope 0 at $DIR/no-spurious-drop-after-call.rs:9:20: 9:22
+        StorageLive(_3);                 // scope 0 at $DIR/no-spurious-drop-after-call.rs:9:20: 9:34
         StorageLive(_4);                 // scope 0 at $DIR/no-spurious-drop-after-call.rs:9:20: 9:22
         _4 = const "";                   // scope 0 at $DIR/no-spurious-drop-after-call.rs:9:20: 9:22
                                          // ty::Const
@@ -19,7 +19,7 @@ fn main() -> () {
                                          // mir::Constant
                                          // + span: $DIR/no-spurious-drop-after-call.rs:9:20: 9:22
                                          // + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [], len: Size { raw: 0 } }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 0 }) }
-        _3 = &(*_4);                     // scope 0 at $DIR/no-spurious-drop-after-call.rs:9:20: 9:22
+        _3 = &(*_4);                     // scope 0 at $DIR/no-spurious-drop-after-call.rs:9:20: 9:34
         _2 = <str as ToString>::to_string(move _3) -> bb1; // scope 0 at $DIR/no-spurious-drop-after-call.rs:9:20: 9:34
                                          // mir::Constant
                                          // + span: $DIR/no-spurious-drop-after-call.rs:9:23: 9:32
diff --git a/src/test/mir-opt/receiver_ptr_mutability.main.mir_map.0.mir b/src/test/mir-opt/receiver_ptr_mutability.main.mir_map.0.mir
index f54c8f8ab4a..f1a1f388c50 100644
--- a/src/test/mir-opt/receiver_ptr_mutability.main.mir_map.0.mir
+++ b/src/test/mir-opt/receiver_ptr_mutability.main.mir_map.0.mir
@@ -10,15 +10,15 @@ fn main() -> () {
     let mut _0: ();                      // return place in scope 0 at $DIR/receiver-ptr-mutability.rs:13:11: 13:11
     let _1: *mut Test as UserTypeProjection { base: UserType(0), projs: [] }; // in scope 0 at $DIR/receiver-ptr-mutability.rs:14:9: 14:12
     let _2: ();                          // in scope 0 at $DIR/receiver-ptr-mutability.rs:15:5: 15:12
-    let mut _3: *const Test;             // in scope 0 at $DIR/receiver-ptr-mutability.rs:15:5: 15:8
+    let mut _3: *const Test;             // in scope 0 at $DIR/receiver-ptr-mutability.rs:15:5: 15:12
     let mut _4: *mut Test;               // in scope 0 at $DIR/receiver-ptr-mutability.rs:15:5: 15:8
     let _6: &&&&*mut Test;               // in scope 0 at $DIR/receiver-ptr-mutability.rs:18:34: 18:41
     let _7: &&&*mut Test;                // in scope 0 at $DIR/receiver-ptr-mutability.rs:18:35: 18:41
     let _8: &&*mut Test;                 // in scope 0 at $DIR/receiver-ptr-mutability.rs:18:36: 18:41
     let _9: &*mut Test;                  // in scope 0 at $DIR/receiver-ptr-mutability.rs:18:37: 18:41
     let _10: ();                         // in scope 0 at $DIR/receiver-ptr-mutability.rs:19:5: 19:16
-    let mut _11: *const Test;            // in scope 0 at $DIR/receiver-ptr-mutability.rs:19:5: 19:12
-    let mut _12: *mut Test;              // in scope 0 at $DIR/receiver-ptr-mutability.rs:19:5: 19:12
+    let mut _11: *const Test;            // in scope 0 at $DIR/receiver-ptr-mutability.rs:19:5: 19:16
+    let mut _12: *mut Test;              // in scope 0 at $DIR/receiver-ptr-mutability.rs:19:5: 19:16
     scope 1 {
         debug ptr => _1;                 // in scope 1 at $DIR/receiver-ptr-mutability.rs:14:9: 14:12
         let _5: &&&&*mut Test as UserTypeProjection { base: UserType(2), projs: [] }; // in scope 1 at $DIR/receiver-ptr-mutability.rs:18:9: 18:16
@@ -39,10 +39,10 @@ fn main() -> () {
         FakeRead(ForLet(None), _1);      // scope 0 at $DIR/receiver-ptr-mutability.rs:14:9: 14:12
         AscribeUserType(_1, o, UserTypeProjection { base: UserType(1), projs: [] }); // scope 0 at $DIR/receiver-ptr-mutability.rs:14:14: 14:23
         StorageLive(_2);                 // scope 1 at $DIR/receiver-ptr-mutability.rs:15:5: 15:12
-        StorageLive(_3);                 // scope 1 at $DIR/receiver-ptr-mutability.rs:15:5: 15:8
+        StorageLive(_3);                 // scope 1 at $DIR/receiver-ptr-mutability.rs:15:5: 15:12
         StorageLive(_4);                 // scope 1 at $DIR/receiver-ptr-mutability.rs:15:5: 15:8
         _4 = _1;                         // scope 1 at $DIR/receiver-ptr-mutability.rs:15:5: 15:8
-        _3 = move _4 as *const Test (Pointer(MutToConstPointer)); // scope 1 at $DIR/receiver-ptr-mutability.rs:15:5: 15:8
+        _3 = move _4 as *const Test (Pointer(MutToConstPointer)); // scope 1 at $DIR/receiver-ptr-mutability.rs:15:5: 15:12
         StorageDead(_4);                 // scope 1 at $DIR/receiver-ptr-mutability.rs:15:7: 15:8
         _2 = Test::x(move _3) -> [return: bb2, unwind: bb4]; // scope 1 at $DIR/receiver-ptr-mutability.rs:15:5: 15:12
                                          // mir::Constant
@@ -67,10 +67,10 @@ fn main() -> () {
         AscribeUserType(_5, o, UserTypeProjection { base: UserType(3), projs: [] }); // scope 1 at $DIR/receiver-ptr-mutability.rs:18:18: 18:31
         StorageDead(_6);                 // scope 1 at $DIR/receiver-ptr-mutability.rs:18:41: 18:42
         StorageLive(_10);                // scope 2 at $DIR/receiver-ptr-mutability.rs:19:5: 19:16
-        StorageLive(_11);                // scope 2 at $DIR/receiver-ptr-mutability.rs:19:5: 19:12
-        StorageLive(_12);                // scope 2 at $DIR/receiver-ptr-mutability.rs:19:5: 19:12
-        _12 = (*(*(*(*_5))));            // scope 2 at $DIR/receiver-ptr-mutability.rs:19:5: 19:12
-        _11 = move _12 as *const Test (Pointer(MutToConstPointer)); // scope 2 at $DIR/receiver-ptr-mutability.rs:19:5: 19:12
+        StorageLive(_11);                // scope 2 at $DIR/receiver-ptr-mutability.rs:19:5: 19:16
+        StorageLive(_12);                // scope 2 at $DIR/receiver-ptr-mutability.rs:19:5: 19:16
+        _12 = (*(*(*(*_5))));            // scope 2 at $DIR/receiver-ptr-mutability.rs:19:5: 19:16
+        _11 = move _12 as *const Test (Pointer(MutToConstPointer)); // scope 2 at $DIR/receiver-ptr-mutability.rs:19:5: 19:16
         StorageDead(_12);                // scope 2 at $DIR/receiver-ptr-mutability.rs:19:11: 19:12
         _10 = Test::x(move _11) -> [return: bb3, unwind: bb4]; // scope 2 at $DIR/receiver-ptr-mutability.rs:19:5: 19:16
                                          // mir::Constant
diff --git a/src/test/mir-opt/retag.main.SimplifyCfg-elaborate-drops.after.mir b/src/test/mir-opt/retag.main.SimplifyCfg-elaborate-drops.after.mir
index cdf7282c8c3..6bb92c5e6bc 100644
--- a/src/test/mir-opt/retag.main.SimplifyCfg-elaborate-drops.after.mir
+++ b/src/test/mir-opt/retag.main.SimplifyCfg-elaborate-drops.after.mir
@@ -4,7 +4,7 @@ fn main() -> () {
     let mut _0: ();                      // return place in scope 0 at $DIR/retag.rs:29:11: 29:11
     let mut _1: i32;                     // in scope 0 at $DIR/retag.rs:30:9: 30:14
     let _2: ();                          // in scope 0 at $DIR/retag.rs:31:5: 37:6
-    let mut _4: &Test;                   // in scope 0 at $DIR/retag.rs:32:17: 32:24
+    let mut _4: &Test;                   // in scope 0 at $DIR/retag.rs:32:17: 32:36
     let _5: Test;                        // in scope 0 at $DIR/retag.rs:32:17: 32:24
     let mut _6: &mut i32;                // in scope 0 at $DIR/retag.rs:32:29: 32:35
     let mut _7: &mut i32;                // in scope 0 at $DIR/retag.rs:32:29: 32:35
@@ -15,7 +15,7 @@ fn main() -> () {
     let mut _17: &i32;                   // in scope 0 at $DIR/retag.rs:44:16: 44:18
     let _18: &i32;                       // in scope 0 at $DIR/retag.rs:44:16: 44:18
     let _19: &i32;                       // in scope 0 at $DIR/retag.rs:47:5: 47:24
-    let mut _20: &Test;                  // in scope 0 at $DIR/retag.rs:47:5: 47:12
+    let mut _20: &Test;                  // in scope 0 at $DIR/retag.rs:47:5: 47:24
     let _21: Test;                       // in scope 0 at $DIR/retag.rs:47:5: 47:12
     let mut _22: &i32;                   // in scope 0 at $DIR/retag.rs:47:21: 47:23
     let _23: &i32;                       // in scope 0 at $DIR/retag.rs:47:21: 47:23
@@ -60,11 +60,11 @@ fn main() -> () {
         _1 = const 0_i32;                // scope 0 at $DIR/retag.rs:30:17: 30:18
         StorageLive(_2);                 // scope 1 at $DIR/retag.rs:31:5: 37:6
         StorageLive(_3);                 // scope 1 at $DIR/retag.rs:32:13: 32:14
-        StorageLive(_4);                 // scope 1 at $DIR/retag.rs:32:17: 32:24
+        StorageLive(_4);                 // scope 1 at $DIR/retag.rs:32:17: 32:36
         StorageLive(_5);                 // scope 1 at $DIR/retag.rs:32:17: 32:24
         _5 = Test(const 0_i32);          // scope 1 at $DIR/retag.rs:32:17: 32:24
-        _4 = &_5;                        // scope 1 at $DIR/retag.rs:32:17: 32:24
-        Retag(_4);                       // scope 1 at $DIR/retag.rs:32:17: 32:24
+        _4 = &_5;                        // scope 1 at $DIR/retag.rs:32:17: 32:36
+        Retag(_4);                       // scope 1 at $DIR/retag.rs:32:17: 32:36
         StorageLive(_6);                 // scope 1 at $DIR/retag.rs:32:29: 32:35
         StorageLive(_7);                 // scope 1 at $DIR/retag.rs:32:29: 32:35
         _7 = &mut _1;                    // scope 1 at $DIR/retag.rs:32:29: 32:35
@@ -140,11 +140,11 @@ fn main() -> () {
         StorageDead(_16);                // scope 6 at $DIR/retag.rs:44:18: 44:19
         StorageDead(_18);                // scope 6 at $DIR/retag.rs:44:19: 44:20
         StorageLive(_19);                // scope 7 at $DIR/retag.rs:47:5: 47:24
-        StorageLive(_20);                // scope 7 at $DIR/retag.rs:47:5: 47:12
+        StorageLive(_20);                // scope 7 at $DIR/retag.rs:47:5: 47:24
         StorageLive(_21);                // scope 7 at $DIR/retag.rs:47:5: 47:12
         _21 = Test(const 0_i32);         // scope 7 at $DIR/retag.rs:47:5: 47:12
-        _20 = &_21;                      // scope 7 at $DIR/retag.rs:47:5: 47:12
-        Retag(_20);                      // scope 7 at $DIR/retag.rs:47:5: 47:12
+        _20 = &_21;                      // scope 7 at $DIR/retag.rs:47:5: 47:24
+        Retag(_20);                      // scope 7 at $DIR/retag.rs:47:5: 47:24
         StorageLive(_22);                // scope 7 at $DIR/retag.rs:47:21: 47:23
         StorageLive(_23);                // scope 7 at $DIR/retag.rs:47:21: 47:23
         _28 = const main::promoted[0];   // scope 7 at $DIR/retag.rs:47:21: 47:23
diff --git a/src/test/run-make-fulldeps/hotplug_codegen_backend/the_backend.rs b/src/test/run-make-fulldeps/hotplug_codegen_backend/the_backend.rs
index d3862309ce4..7c16f7bdaf7 100644
--- a/src/test/run-make-fulldeps/hotplug_codegen_backend/the_backend.rs
+++ b/src/test/run-make-fulldeps/hotplug_codegen_backend/the_backend.rs
@@ -2,11 +2,12 @@
 #![deny(warnings)]
 
 extern crate rustc_codegen_ssa;
-extern crate rustc_errors;
-extern crate rustc_middle;
 extern crate rustc_data_structures;
 extern crate rustc_driver;
+extern crate rustc_errors;
 extern crate rustc_hir;
+extern crate rustc_metadata;
+extern crate rustc_middle;
 extern crate rustc_session;
 extern crate rustc_span;
 extern crate rustc_symbol_mangling;
@@ -16,8 +17,8 @@ use rustc_codegen_ssa::traits::CodegenBackend;
 use rustc_codegen_ssa::{CodegenResults, CrateInfo};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::ErrorReported;
+use rustc_metadata::EncodedMetadata;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
-use rustc_middle::middle::cstore::EncodedMetadata;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::config::OutputFilenames;
 use rustc_session::Session;
diff --git a/src/test/run-make-fulldeps/target-specs/foo.rs b/src/test/run-make-fulldeps/target-specs/foo.rs
index 9ff33e24d04..d576a1dd281 100644
--- a/src/test/run-make-fulldeps/target-specs/foo.rs
+++ b/src/test/run-make-fulldeps/target-specs/foo.rs
@@ -11,7 +11,7 @@ trait Sized {}
 auto trait Freeze {}
 
 #[lang = "start"]
-fn start(_main: *const u8, _argc: isize, _argv: *const *const u8) -> isize {
+fn start<T>(_main: fn() -> T, _argc: isize, _argv: *const *const u8) -> isize {
     0
 }
 
diff --git a/src/test/rustdoc-json/unions/impl.rs b/src/test/rustdoc-json/unions/impl.rs
new file mode 100644
index 00000000000..0388b4a8c3c
--- /dev/null
+++ b/src/test/rustdoc-json/unions/impl.rs
@@ -0,0 +1,15 @@
+#![no_std]
+
+// @has impl.json "$.index[*][?(@.name=='Ux')].visibility" \"public\"
+// @has - "$.index[*][?(@.name=='Ux')].kind" \"union\"
+pub union Ux {
+    a: u32,
+    b: u64
+}
+
+// @has - "$.index[*][?(@.name=='Num')].visibility" \"public\"
+// @has - "$.index[*][?(@.name=='Num')].kind" \"trait\"
+pub trait Num {}
+
+// @count - "$.index[*][?(@.name=='Ux')].inner.impls" 1
+impl Num for Ux {}
diff --git a/src/test/ui/array-slice-vec/vec-mut-iter-borrow.stderr b/src/test/ui/array-slice-vec/vec-mut-iter-borrow.stderr
index 679fd899773..0ec263c850e 100644
--- a/src/test/ui/array-slice-vec/vec-mut-iter-borrow.stderr
+++ b/src/test/ui/array-slice-vec/vec-mut-iter-borrow.stderr
@@ -7,7 +7,7 @@ LL |     for x in &mut xs {
    |              first mutable borrow occurs here
    |              first borrow later used here
 LL |         xs.push(1)
-   |         ^^ second mutable borrow occurs here
+   |         ^^^^^^^^^^ second mutable borrow occurs here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/asm/issue-89305.rs b/src/test/ui/asm/issue-89305.rs
new file mode 100644
index 00000000000..bdcf3f305eb
--- /dev/null
+++ b/src/test/ui/asm/issue-89305.rs
@@ -0,0 +1,14 @@
+// Regression test for #89305, where a variable was erroneously reported
+// as both unused and possibly-uninitialized.
+
+// check-pass
+
+#![feature(asm)]
+#![warn(unused)]
+
+fn main() {
+    unsafe {
+        let x: () = asm!("nop");
+        //~^ WARNING: unused variable: `x`
+    }
+}
diff --git a/src/test/ui/asm/issue-89305.stderr b/src/test/ui/asm/issue-89305.stderr
new file mode 100644
index 00000000000..9cc127b44d0
--- /dev/null
+++ b/src/test/ui/asm/issue-89305.stderr
@@ -0,0 +1,15 @@
+warning: unused variable: `x`
+  --> $DIR/issue-89305.rs:11:13
+   |
+LL |         let x: () = asm!("nop");
+   |             ^ help: if this is intentional, prefix it with an underscore: `_x`
+   |
+note: the lint level is defined here
+  --> $DIR/issue-89305.rs:7:9
+   |
+LL | #![warn(unused)]
+   |         ^^^^^^
+   = note: `#[warn(unused_variables)]` implied by `#[warn(unused)]`
+
+warning: 1 warning emitted
+
diff --git a/src/test/ui/associated-consts/associated-const-ambiguity-report.stderr b/src/test/ui/associated-consts/associated-const-ambiguity-report.stderr
index d4c12b8e061..60cf9a533cd 100644
--- a/src/test/ui/associated-consts/associated-const-ambiguity-report.stderr
+++ b/src/test/ui/associated-consts/associated-const-ambiguity-report.stderr
@@ -16,12 +16,12 @@ LL |     const ID: i32 = 3;
    |     ^^^^^^^^^^^^^^^^^^
 help: disambiguate the associated constant for candidate #1
    |
-LL | const X: i32 = Foo::ID;
-   |                ~~~~~
+LL | const X: i32 = <i32 as Foo>::ID;
+   |                ~~~~~~~~~~~~~~
 help: disambiguate the associated constant for candidate #2
    |
-LL | const X: i32 = Bar::ID;
-   |                ~~~~~
+LL | const X: i32 = <i32 as Bar>::ID;
+   |                ~~~~~~~~~~~~~~
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/associated-types/hr-associated-type-bound-2.stderr b/src/test/ui/associated-types/hr-associated-type-bound-2.stderr
index 079989f2331..fe9b4d630b9 100644
--- a/src/test/ui/associated-types/hr-associated-type-bound-2.stderr
+++ b/src/test/ui/associated-types/hr-associated-type-bound-2.stderr
@@ -9,7 +9,7 @@ LL | |     type U = str;
 LL | | }
    | |_^
    |
-   = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`hr_associated_type_bound_2`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`hr_associated_type_bound_2`)
 note: required because of the requirements on the impl of `for<'b> X<'b>` for `u32`
   --> $DIR/hr-associated-type-bound-2.rs:11:6
    |
@@ -24,7 +24,7 @@ error[E0275]: overflow evaluating the requirement `for<'b> u32: X<'b>`
 LL |     type U = str;
    |     ^^^^^^^^^^^^^
    |
-   = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`hr_associated_type_bound_2`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`hr_associated_type_bound_2`)
 note: required because of the requirements on the impl of `for<'b> X<'b>` for `u32`
   --> $DIR/hr-associated-type-bound-2.rs:11:6
    |
diff --git a/src/test/ui/async-await/issue-61452.stderr b/src/test/ui/async-await/issue-61452.stderr
index f2dec87baf0..2d3bb48e03b 100644
--- a/src/test/ui/async-await/issue-61452.stderr
+++ b/src/test/ui/async-await/issue-61452.stderr
@@ -4,7 +4,7 @@ error[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable
 LL | pub async fn f(x: Option<usize>) {
    |                - help: consider changing this to be mutable: `mut x`
 LL |     x.take();
-   |     ^ cannot borrow as mutable
+   |     ^^^^^^^^ cannot borrow as mutable
 
 error[E0384]: cannot assign twice to immutable variable `x`
   --> $DIR/issue-61452.rs:9:5
diff --git a/src/test/ui/async-await/issues/issue-61187.stderr b/src/test/ui/async-await/issues/issue-61187.stderr
index 4d361c824dd..163053471b5 100644
--- a/src/test/ui/async-await/issues/issue-61187.stderr
+++ b/src/test/ui/async-await/issues/issue-61187.stderr
@@ -4,7 +4,7 @@ error[E0596]: cannot borrow `data` as mutable, as it is not declared as mutable
 LL | async fn response(data: Vec<u8>) {
    |                   ---- help: consider changing this to be mutable: `mut data`
 LL |     data.reverse();
-   |     ^^^^ cannot borrow as mutable
+   |     ^^^^^^^^^^^^^^ cannot borrow as mutable
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/autoref-autoderef/issue-38940.stderr b/src/test/ui/autoref-autoderef/issue-38940.stderr
index 0671cede73b..a560334314c 100644
--- a/src/test/ui/autoref-autoderef/issue-38940.stderr
+++ b/src/test/ui/autoref-autoderef/issue-38940.stderr
@@ -4,7 +4,7 @@ error[E0055]: reached the recursion limit while auto-dereferencing `J`
 LL |     let x: &Bottom = &t;
    |                      ^^ deref recursion limit reached
    |
-   = help: consider adding a `#![recursion_limit="20"]` attribute to your crate (`issue_38940`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "20"]` attribute to your crate (`issue_38940`)
 
 error[E0308]: mismatched types
   --> $DIR/issue-38940.rs:43:22
diff --git a/src/test/ui/binop/binop-move-semantics.stderr b/src/test/ui/binop/binop-move-semantics.stderr
index 7721f8827db..2cd6d1abfdc 100644
--- a/src/test/ui/binop/binop-move-semantics.stderr
+++ b/src/test/ui/binop/binop-move-semantics.stderr
@@ -30,7 +30,7 @@ LL |     x
    |     - value moved here
 LL |     +
 LL |     x.clone();
-   |     ^ value borrowed here after move
+   |     ^^^^^^^^^ value borrowed here after move
    |
 help: consider further restricting this bound
    |
diff --git a/src/test/ui/borrowck/borrow-tuple-fields.stderr b/src/test/ui/borrowck/borrow-tuple-fields.stderr
index 503ea49d74e..ad628abcbfc 100644
--- a/src/test/ui/borrowck/borrow-tuple-fields.stderr
+++ b/src/test/ui/borrowck/borrow-tuple-fields.stderr
@@ -7,7 +7,7 @@ LL |     let y = x;
    |             ^ move out of `x` occurs here
 LL | 
 LL |     r.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error[E0502]: cannot borrow `x.0` as mutable because it is also borrowed as immutable
   --> $DIR/borrow-tuple-fields.rs:18:13
@@ -17,7 +17,7 @@ LL |     let a = &x.0;
 LL |     let b = &mut x.0;
    |             ^^^^^^^^ mutable borrow occurs here
 LL |     a.use_ref();
-   |     - immutable borrow later used here
+   |     ----------- immutable borrow later used here
 
 error[E0499]: cannot borrow `x.0` as mutable more than once at a time
   --> $DIR/borrow-tuple-fields.rs:23:13
@@ -27,7 +27,7 @@ LL |     let a = &mut x.0;
 LL |     let b = &mut x.0;
    |             ^^^^^^^^ second mutable borrow occurs here
 LL |     a.use_ref();
-   |     - first borrow later used here
+   |     ----------- first borrow later used here
 
 error[E0505]: cannot move out of `x` because it is borrowed
   --> $DIR/borrow-tuple-fields.rs:28:13
@@ -37,7 +37,7 @@ LL |     let r = &x.0;
 LL |     let y = x;
    |             ^ move out of `x` occurs here
 LL |     r.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error[E0502]: cannot borrow `x.0` as mutable because it is also borrowed as immutable
   --> $DIR/borrow-tuple-fields.rs:33:13
@@ -47,7 +47,7 @@ LL |     let a = &x.0;
 LL |     let b = &mut x.0;
    |             ^^^^^^^^ mutable borrow occurs here
 LL |     a.use_ref();
-   |     - immutable borrow later used here
+   |     ----------- immutable borrow later used here
 
 error[E0499]: cannot borrow `x.0` as mutable more than once at a time
   --> $DIR/borrow-tuple-fields.rs:38:13
@@ -57,7 +57,7 @@ LL |     let a = &mut x.0;
 LL |     let b = &mut x.0;
    |             ^^^^^^^^ second mutable borrow occurs here
 LL |     a.use_mut();
-   |     - first borrow later used here
+   |     ----------- first borrow later used here
 
 error: aborting due to 6 previous errors
 
diff --git a/src/test/ui/borrowck/borrowck-argument.stderr b/src/test/ui/borrowck/borrowck-argument.stderr
index cf158331409..d4d646e390c 100644
--- a/src/test/ui/borrowck/borrowck-argument.stderr
+++ b/src/test/ui/borrowck/borrowck-argument.stderr
@@ -4,7 +4,7 @@ error[E0596]: cannot borrow `arg` as mutable, as it is not declared as mutable
 LL | fn func(arg: S) {
    |         --- help: consider changing this to be mutable: `mut arg`
 LL |     arg.mutate();
-   |     ^^^ cannot borrow as mutable
+   |     ^^^^^^^^^^^^ cannot borrow as mutable
 
 error[E0596]: cannot borrow `arg` as mutable, as it is not declared as mutable
   --> $DIR/borrowck-argument.rs:15:9
@@ -12,7 +12,7 @@ error[E0596]: cannot borrow `arg` as mutable, as it is not declared as mutable
 LL |     fn method(&self, arg: S) {
    |                      --- help: consider changing this to be mutable: `mut arg`
 LL |         arg.mutate();
-   |         ^^^ cannot borrow as mutable
+   |         ^^^^^^^^^^^^ cannot borrow as mutable
 
 error[E0596]: cannot borrow `arg` as mutable, as it is not declared as mutable
   --> $DIR/borrowck-argument.rs:21:9
@@ -20,13 +20,13 @@ error[E0596]: cannot borrow `arg` as mutable, as it is not declared as mutable
 LL |     fn default(&self, arg: S) {
    |                       --- help: consider changing this to be mutable: `mut arg`
 LL |         arg.mutate();
-   |         ^^^ cannot borrow as mutable
+   |         ^^^^^^^^^^^^ cannot borrow as mutable
 
 error[E0596]: cannot borrow `arg` as mutable, as it is not declared as mutable
   --> $DIR/borrowck-argument.rs:32:17
    |
 LL |     (|arg: S| { arg.mutate() })(s);
-   |       ---       ^^^ cannot borrow as mutable
+   |       ---       ^^^^^^^^^^^^ cannot borrow as mutable
    |       |
    |       help: consider changing this to be mutable: `mut arg`
 
diff --git a/src/test/ui/borrowck/borrowck-auto-mut-ref-to-immut-var.stderr b/src/test/ui/borrowck/borrowck-auto-mut-ref-to-immut-var.stderr
index 3ed76c13f6a..186ecddd6d6 100644
--- a/src/test/ui/borrowck/borrowck-auto-mut-ref-to-immut-var.stderr
+++ b/src/test/ui/borrowck/borrowck-auto-mut-ref-to-immut-var.stderr
@@ -4,7 +4,7 @@ error[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable
 LL |     let x = Foo { x: 3 };
    |         - help: consider changing this to be mutable: `mut x`
 LL |     x.printme();
-   |     ^ cannot borrow as mutable
+   |     ^^^^^^^^^^^ cannot borrow as mutable
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/borrowck-borrow-immut-deref-of-box-as-mut.stderr b/src/test/ui/borrowck/borrowck-borrow-immut-deref-of-box-as-mut.stderr
index 76dc01202f6..237071e16fc 100644
--- a/src/test/ui/borrowck/borrowck-borrow-immut-deref-of-box-as-mut.stderr
+++ b/src/test/ui/borrowck/borrowck-borrow-immut-deref-of-box-as-mut.stderr
@@ -4,7 +4,7 @@ error[E0596]: cannot borrow `*a` as mutable, as `a` is not declared as mutable
 LL |     let a: Box<_> = Box::new(A);
    |         - help: consider changing this to be mutable: `mut a`
 LL |     a.foo();
-   |     ^ cannot borrow as mutable
+   |     ^^^^^^^ cannot borrow as mutable
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/borrowck-borrow-mut-object-twice.stderr b/src/test/ui/borrowck/borrowck-borrow-mut-object-twice.stderr
index fa0ae318e72..42b6c34cd2f 100644
--- a/src/test/ui/borrowck/borrowck-borrow-mut-object-twice.stderr
+++ b/src/test/ui/borrowck/borrowck-borrow-mut-object-twice.stderr
@@ -2,11 +2,11 @@ error[E0499]: cannot borrow `*x` as mutable more than once at a time
   --> $DIR/borrowck-borrow-mut-object-twice.rs:13:5
    |
 LL |     let y = x.f1();
-   |             - first mutable borrow occurs here
+   |             ------ first mutable borrow occurs here
 LL |     x.f2();
-   |     ^ second mutable borrow occurs here
+   |     ^^^^^^ second mutable borrow occurs here
 LL |     y.use_ref();
-   |     - first borrow later used here
+   |     ----------- first borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/borrowck-borrow-overloaded-auto-deref.stderr b/src/test/ui/borrowck/borrowck-borrow-overloaded-auto-deref.stderr
index 426d5bc4726..fdf6568d839 100644
--- a/src/test/ui/borrowck/borrowck-borrow-overloaded-auto-deref.stderr
+++ b/src/test/ui/borrowck/borrowck-borrow-overloaded-auto-deref.stderr
@@ -58,7 +58,7 @@ error[E0596]: cannot borrow data in an `Rc` as mutable
   --> $DIR/borrowck-borrow-overloaded-auto-deref.rs:72:5
    |
 LL |     x.set(0, 0);
-   |     ^ cannot borrow as mutable
+   |     ^^^^^^^^^^^ cannot borrow as mutable
    |
    = help: trait `DerefMut` is required to modify through a dereference, but it is not implemented for `Rc<Point>`
 
@@ -66,7 +66,7 @@ error[E0596]: cannot borrow data in an `Rc` as mutable
   --> $DIR/borrowck-borrow-overloaded-auto-deref.rs:76:5
    |
 LL |     x.set(0, 0);
-   |     ^ cannot borrow as mutable
+   |     ^^^^^^^^^^^ cannot borrow as mutable
    |
    = help: trait `DerefMut` is required to modify through a dereference, but it is not implemented for `Rc<Point>`
 
@@ -74,7 +74,7 @@ error[E0596]: cannot borrow data in an `Rc` as mutable
   --> $DIR/borrowck-borrow-overloaded-auto-deref.rs:84:5
    |
 LL |     x.y_mut()
-   |     ^ cannot borrow as mutable
+   |     ^^^^^^^^^ cannot borrow as mutable
    |
    = help: trait `DerefMut` is required to modify through a dereference, but it is not implemented for `Rc<Point>`
 
@@ -82,7 +82,7 @@ error[E0596]: cannot borrow data in an `Rc` as mutable
   --> $DIR/borrowck-borrow-overloaded-auto-deref.rs:88:5
    |
 LL |     x.y_mut()
-   |     ^ cannot borrow as mutable
+   |     ^^^^^^^^^ cannot borrow as mutable
    |
    = help: trait `DerefMut` is required to modify through a dereference, but it is not implemented for `Rc<Point>`
 
@@ -90,7 +90,7 @@ error[E0596]: cannot borrow data in an `Rc` as mutable
   --> $DIR/borrowck-borrow-overloaded-auto-deref.rs:92:6
    |
 LL |     *x.y_mut() = 3;
-   |      ^ cannot borrow as mutable
+   |      ^^^^^^^^^ cannot borrow as mutable
    |
    = help: trait `DerefMut` is required to modify through a dereference, but it is not implemented for `Rc<Point>`
 
@@ -98,7 +98,7 @@ error[E0596]: cannot borrow data in an `Rc` as mutable
   --> $DIR/borrowck-borrow-overloaded-auto-deref.rs:96:6
    |
 LL |     *x.y_mut() = 3;
-   |      ^ cannot borrow as mutable
+   |      ^^^^^^^^^ cannot borrow as mutable
    |
    = help: trait `DerefMut` is required to modify through a dereference, but it is not implemented for `Rc<Point>`
 
@@ -106,7 +106,7 @@ error[E0596]: cannot borrow data in an `Rc` as mutable
   --> $DIR/borrowck-borrow-overloaded-auto-deref.rs:100:6
    |
 LL |     *x.y_mut() = 3;
-   |      ^ cannot borrow as mutable
+   |      ^^^^^^^^^ cannot borrow as mutable
    |
    = help: trait `DerefMut` is required to modify through a dereference, but it is not implemented for `Rc<Point>`
 
diff --git a/src/test/ui/borrowck/borrowck-borrowed-uniq-rvalue.stderr b/src/test/ui/borrowck/borrowck-borrowed-uniq-rvalue.stderr
index c91a4377b4c..01379ed8512 100644
--- a/src/test/ui/borrowck/borrowck-borrowed-uniq-rvalue.stderr
+++ b/src/test/ui/borrowck/borrowck-borrowed-uniq-rvalue.stderr
@@ -7,7 +7,7 @@ LL |     buggy_map.insert(42, &*Box::new(1));
    |                            creates a temporary which is freed while still in use
 ...
 LL |     buggy_map.insert(43, &*tmp);
-   |     --------- borrow later used here
+   |     --------------------------- borrow later used here
    |
    = note: consider using a `let` binding to create a longer lived value
 
diff --git a/src/test/ui/borrowck/borrowck-closures-unique-imm.stderr b/src/test/ui/borrowck/borrowck-closures-unique-imm.stderr
index b8bbb31a355..0c5fd39b718 100644
--- a/src/test/ui/borrowck/borrowck-closures-unique-imm.stderr
+++ b/src/test/ui/borrowck/borrowck-closures-unique-imm.stderr
@@ -6,7 +6,7 @@ LL |         let p = &this.x;
 LL |         &mut this.x;
    |         ^^^^^^^^^^^ mutable borrow occurs here
 LL |         p.use_ref();
-   |         - immutable borrow later used here
+   |         ----------- immutable borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/borrowck-describe-lvalue.stderr b/src/test/ui/borrowck/borrowck-describe-lvalue.stderr
index 4b9c5a2a98f..f909dbc4082 100644
--- a/src/test/ui/borrowck/borrowck-describe-lvalue.stderr
+++ b/src/test/ui/borrowck/borrowck-describe-lvalue.stderr
@@ -41,7 +41,7 @@ error[E0503]: cannot use `f.x` because it was mutably borrowed
   --> $DIR/borrowck-describe-lvalue.rs:37:9
    |
 LL |         let x = f.x();
-   |                 - borrow of `f` occurs here
+   |                 ----- borrow of `f` occurs here
 LL |         f.x;
    |         ^^^ use of borrowed `f`
 LL |         drop(x);
@@ -51,7 +51,7 @@ error[E0503]: cannot use `g.0` because it was mutably borrowed
   --> $DIR/borrowck-describe-lvalue.rs:44:9
    |
 LL |         let x = g.x();
-   |                 - borrow of `g` occurs here
+   |                 ----- borrow of `g` occurs here
 LL |         g.0;
    |         ^^^ use of borrowed `g`
 LL |         drop(x);
@@ -71,7 +71,7 @@ error[E0503]: cannot use `e.0` because it was mutably borrowed
   --> $DIR/borrowck-describe-lvalue.rs:59:20
    |
 LL |         let x = e.x();
-   |                 - borrow of `e` occurs here
+   |                 ----- borrow of `e` occurs here
 LL |         match e {
 LL |             Baz::X(value) => value
    |                    ^^^^^ use of borrowed `e`
@@ -93,7 +93,7 @@ error[E0503]: cannot use `f.x` because it was mutably borrowed
   --> $DIR/borrowck-describe-lvalue.rs:74:9
    |
 LL |         let x = f.x();
-   |                 - borrow of `*f` occurs here
+   |                 ----- borrow of `*f` occurs here
 LL |         f.x;
    |         ^^^ use of borrowed `*f`
 LL |         drop(x);
@@ -103,7 +103,7 @@ error[E0503]: cannot use `g.0` because it was mutably borrowed
   --> $DIR/borrowck-describe-lvalue.rs:81:9
    |
 LL |         let x = g.x();
-   |                 - borrow of `*g` occurs here
+   |                 ----- borrow of `*g` occurs here
 LL |         g.0;
    |         ^^^ use of borrowed `*g`
 LL |         drop(x);
@@ -123,7 +123,7 @@ error[E0503]: cannot use `e.0` because it was mutably borrowed
   --> $DIR/borrowck-describe-lvalue.rs:96:20
    |
 LL |         let x = e.x();
-   |                 - borrow of `*e` occurs here
+   |                 ----- borrow of `*e` occurs here
 LL |         match *e {
 LL |             Baz::X(value) => value
    |                    ^^^^^ use of borrowed `*e`
diff --git a/src/test/ui/borrowck/borrowck-for-loop-head-linkage.nll.stderr b/src/test/ui/borrowck/borrowck-for-loop-head-linkage.nll.stderr
deleted file mode 100644
index 3468f29fb1a..00000000000
--- a/src/test/ui/borrowck/borrowck-for-loop-head-linkage.nll.stderr
+++ /dev/null
@@ -1,27 +0,0 @@
-error[E0502]: cannot borrow `vector` as mutable because it is also borrowed as immutable
-  --> $DIR/borrowck-for-loop-head-linkage.rs:7:9
-   |
-LL |     for &x in &vector {
-   |               -------
-   |               |
-   |               immutable borrow occurs here
-   |               immutable borrow later used here
-LL |         let cap = vector.capacity();
-LL |         vector.extend(repeat(0));
-   |         ^^^^^^ mutable borrow occurs here
-
-error[E0502]: cannot borrow `vector` as mutable because it is also borrowed as immutable
-  --> $DIR/borrowck-for-loop-head-linkage.rs:8:9
-   |
-LL |     for &x in &vector {
-   |               -------
-   |               |
-   |               immutable borrow occurs here
-   |               immutable borrow later used here
-...
-LL |         vector[1] = 5;
-   |         ^^^^^^ mutable borrow occurs here
-
-error: aborting due to 2 previous errors
-
-For more information about this error, try `rustc --explain E0502`.
diff --git a/src/test/ui/borrowck/borrowck-insert-during-each.stderr b/src/test/ui/borrowck/borrowck-insert-during-each.stderr
index a1ac45795fa..99d08e905d5 100644
--- a/src/test/ui/borrowck/borrowck-insert-during-each.stderr
+++ b/src/test/ui/borrowck/borrowck-insert-during-each.stderr
@@ -16,15 +16,17 @@ LL | |         })
 error[E0500]: closure requires unique access to `f` but it is already borrowed
   --> $DIR/borrowck-insert-during-each.rs:18:9
    |
-LL |     f.foo(
-   |     - --- first borrow later used by call
-   |     |
-   |     borrow occurs here
-LL |
-LL |         |a| {
-   |         ^^^ closure construction occurs here
-LL |             f.n.insert(*a);
-   |             --- second borrow occurs due to use of `f` in closure
+LL |       f.foo(
+   |       - --- first borrow later used by call
+   |  _____|
+   | |
+LL | |
+LL | |         |a| {
+   | |         ^^^ closure construction occurs here
+LL | |             f.n.insert(*a);
+   | |             --- second borrow occurs due to use of `f` in closure
+LL | |         })
+   | |__________- borrow occurs here
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/borrowck/borrowck-issue-2657-1.stderr b/src/test/ui/borrowck/borrowck-issue-2657-1.stderr
index 4ea4eb8f007..390bb9384f8 100644
--- a/src/test/ui/borrowck/borrowck-issue-2657-1.stderr
+++ b/src/test/ui/borrowck/borrowck-issue-2657-1.stderr
@@ -6,7 +6,7 @@ LL |       Some(ref _y) => {
 LL |         let _a = x;
    |                  ^ move out of `x` occurs here
 LL |         _y.use_ref();
-   |         -- borrow later used here
+   |         ------------ borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/borrowck-lend-flow-if.stderr b/src/test/ui/borrowck/borrowck-lend-flow-if.stderr
index 68a82bdb57c..e47efc0e0b3 100644
--- a/src/test/ui/borrowck/borrowck-lend-flow-if.stderr
+++ b/src/test/ui/borrowck/borrowck-lend-flow-if.stderr
@@ -7,7 +7,7 @@ LL |     }
 LL |     borrow_mut(&mut *v);
    |                ^^^^^^^ mutable borrow occurs here
 LL |     _w.use_ref();
-   |     -- immutable borrow later used here
+   |     ------------ immutable borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/borrowck-lend-flow.stderr b/src/test/ui/borrowck/borrowck-lend-flow.stderr
index 07b11b3e728..40c14f54cb8 100644
--- a/src/test/ui/borrowck/borrowck-lend-flow.stderr
+++ b/src/test/ui/borrowck/borrowck-lend-flow.stderr
@@ -6,7 +6,7 @@ LL |     let _w = &v;
 LL |     borrow_mut(&mut *v);
    |                ^^^^^^^ mutable borrow occurs here
 LL |     _w.use_ref();
-   |     -- immutable borrow later used here
+   |     ------------ immutable borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/borrowck-loan-blocks-move-cc.stderr b/src/test/ui/borrowck/borrowck-loan-blocks-move-cc.stderr
index ac25502ad05..3548da35b61 100644
--- a/src/test/ui/borrowck/borrowck-loan-blocks-move-cc.stderr
+++ b/src/test/ui/borrowck/borrowck-loan-blocks-move-cc.stderr
@@ -10,7 +10,7 @@ LL |         println!("v={}", *v);
    |                          -- move occurs due to use in closure
 LL |     });
 LL |     w.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error[E0505]: cannot move out of `v` because it is borrowed
   --> $DIR/borrowck-loan-blocks-move-cc.rs:24:19
@@ -24,7 +24,7 @@ LL |         println!("v={}", *v);
    |                          -- move occurs due to use in closure
 LL |     });
 LL |     w.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/borrowck/borrowck-loan-blocks-move.stderr b/src/test/ui/borrowck/borrowck-loan-blocks-move.stderr
index 615660febbc..b5c6b101f76 100644
--- a/src/test/ui/borrowck/borrowck-loan-blocks-move.stderr
+++ b/src/test/ui/borrowck/borrowck-loan-blocks-move.stderr
@@ -6,7 +6,7 @@ LL |     let w = &v;
 LL |     take(v);
    |          ^ move out of `v` occurs here
 LL |     w.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/borrowck-loan-in-overloaded-op.stderr b/src/test/ui/borrowck/borrowck-loan-in-overloaded-op.stderr
index cd288065b74..0dd720ff6ce 100644
--- a/src/test/ui/borrowck/borrowck-loan-in-overloaded-op.stderr
+++ b/src/test/ui/borrowck/borrowck-loan-in-overloaded-op.stderr
@@ -4,7 +4,7 @@ error[E0382]: borrow of moved value: `x`
 LL |     let x = Foo(Box::new(3));
    |         - move occurs because `x` has type `Foo`, which does not implement the `Copy` trait
 LL |     let _y = {x} + x.clone(); // the `{x}` forces a move to occur
-   |               -    ^ value borrowed here after move
+   |               -    ^^^^^^^^^ value borrowed here after move
    |               |
    |               value moved here
 
diff --git a/src/test/ui/borrowck/borrowck-loan-rcvr-overloaded-op.stderr b/src/test/ui/borrowck/borrowck-loan-rcvr-overloaded-op.stderr
index aa874c34a22..1d8d04c9181 100644
--- a/src/test/ui/borrowck/borrowck-loan-rcvr-overloaded-op.stderr
+++ b/src/test/ui/borrowck/borrowck-loan-rcvr-overloaded-op.stderr
@@ -17,7 +17,7 @@ LL |     let q = &mut p;
    |             ------ mutable borrow occurs here
 ...
 LL |     p.times(3);
-   |     ^ immutable borrow occurs here
+   |     ^^^^^^^^^^ immutable borrow occurs here
 LL | 
 LL |     *q + 3; // OK to use the new alias `q`
    |     -- mutable borrow later used here
diff --git a/src/test/ui/borrowck/borrowck-loan-rcvr.stderr b/src/test/ui/borrowck/borrowck-loan-rcvr.stderr
index 489ec7d04ed..74cad575d27 100644
--- a/src/test/ui/borrowck/borrowck-loan-rcvr.stderr
+++ b/src/test/ui/borrowck/borrowck-loan-rcvr.stderr
@@ -1,13 +1,15 @@
 error[E0502]: cannot borrow `p` as mutable because it is also borrowed as immutable
   --> $DIR/borrowck-loan-rcvr.rs:23:14
    |
-LL |     p.blockm(|| {
-   |     - ------ ^^ mutable borrow occurs here
-   |     | |
-   |     | immutable borrow later used by call
-   |     immutable borrow occurs here
-LL |         p.x = 10;
-   |         --- second borrow occurs due to use of `p` in closure
+LL |       p.blockm(|| {
+   |       - ------ ^^ mutable borrow occurs here
+   |       | |
+   |  _____| immutable borrow later used by call
+   | |
+LL | |         p.x = 10;
+   | |         --- second borrow occurs due to use of `p` in closure
+LL | |     })
+   | |______- immutable borrow occurs here
 
 error[E0502]: cannot borrow `p` as immutable because it is also borrowed as mutable
   --> $DIR/borrowck-loan-rcvr.rs:34:5
@@ -15,7 +17,7 @@ error[E0502]: cannot borrow `p` as immutable because it is also borrowed as muta
 LL |     let l = &mut p;
    |             ------ mutable borrow occurs here
 LL |     p.impurem();
-   |     ^ immutable borrow occurs here
+   |     ^^^^^^^^^^^ immutable borrow occurs here
 LL | 
 LL |     l.x += 1;
    |     -------- mutable borrow later used here
diff --git a/src/test/ui/borrowck/borrowck-move-from-subpath-of-borrowed-path.stderr b/src/test/ui/borrowck/borrowck-move-from-subpath-of-borrowed-path.stderr
index e4840fba672..b305e3c0a16 100644
--- a/src/test/ui/borrowck/borrowck-move-from-subpath-of-borrowed-path.stderr
+++ b/src/test/ui/borrowck/borrowck-move-from-subpath-of-borrowed-path.stderr
@@ -7,7 +7,7 @@ LL |
 LL |     let z = *a;
    |             ^^ move out of `*a` occurs here
 LL |     b.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/borrowck-move-mut-base-ptr.stderr b/src/test/ui/borrowck/borrowck-move-mut-base-ptr.stderr
index 77f5b72e51c..d5ff0c501c4 100644
--- a/src/test/ui/borrowck/borrowck-move-mut-base-ptr.stderr
+++ b/src/test/ui/borrowck/borrowck-move-mut-base-ptr.stderr
@@ -7,7 +7,7 @@ LL |     let t1 = t0;
    |              ^^ move out of `t0` occurs here
 LL |     *t1 = 22;
 LL |     p.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/borrowck-move-out-of-overloaded-auto-deref.stderr b/src/test/ui/borrowck/borrowck-move-out-of-overloaded-auto-deref.stderr
index 0a29d2bb1d5..79745065070 100644
--- a/src/test/ui/borrowck/borrowck-move-out-of-overloaded-auto-deref.stderr
+++ b/src/test/ui/borrowck/borrowck-move-out-of-overloaded-auto-deref.stderr
@@ -2,7 +2,7 @@ error[E0507]: cannot move out of an `Rc`
   --> $DIR/borrowck-move-out-of-overloaded-auto-deref.rs:4:14
    |
 LL |     let _x = Rc::new(vec![1, 2]).into_iter();
-   |              ^^^^^^^^^^^^^^^^^^^ move occurs because value has type `Vec<i32>`, which does not implement the `Copy` trait
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ move occurs because value has type `Vec<i32>`, which does not implement the `Copy` trait
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/borrowck-mut-borrow-linear-errors.stderr b/src/test/ui/borrowck/borrowck-mut-borrow-linear-errors.stderr
index a4090777939..15ac737606d 100644
--- a/src/test/ui/borrowck/borrowck-mut-borrow-linear-errors.stderr
+++ b/src/test/ui/borrowck/borrowck-mut-borrow-linear-errors.stderr
@@ -5,8 +5,9 @@ LL |             1 => { addr.push(&mut x); }
    |                              ^^^^^^ second mutable borrow occurs here
 LL |             2 => { addr.push(&mut x); }
 LL |             _ => { addr.push(&mut x); }
-   |                    ----      ------ first mutable borrow occurs here
-   |                    |
+   |                    -----------------
+   |                    |         |
+   |                    |         first mutable borrow occurs here
    |                    first borrow later used here
 
 error[E0499]: cannot borrow `x` as mutable more than once at a time
@@ -15,8 +16,9 @@ error[E0499]: cannot borrow `x` as mutable more than once at a time
 LL |             2 => { addr.push(&mut x); }
    |                              ^^^^^^ second mutable borrow occurs here
 LL |             _ => { addr.push(&mut x); }
-   |                    ----      ------ first mutable borrow occurs here
-   |                    |
+   |                    -----------------
+   |                    |         |
+   |                    |         first mutable borrow occurs here
    |                    first borrow later used here
 
 error[E0499]: cannot borrow `x` as mutable more than once at a time
diff --git a/src/test/ui/borrowck/borrowck-mut-borrow-of-mut-base-ptr.stderr b/src/test/ui/borrowck/borrowck-mut-borrow-of-mut-base-ptr.stderr
index f2baee09376..ef811b84905 100644
--- a/src/test/ui/borrowck/borrowck-mut-borrow-of-mut-base-ptr.stderr
+++ b/src/test/ui/borrowck/borrowck-mut-borrow-of-mut-base-ptr.stderr
@@ -7,7 +7,7 @@ LL |     let mut t2 = &mut t0;
    |                  ^^^^^^^ mutable borrow occurs here
 LL |     **t2 += 1;              // Mutates `*t0`
 LL |     p.use_ref();
-   |     - immutable borrow later used here
+   |     ----------- immutable borrow later used here
 
 error[E0499]: cannot borrow `t0` as mutable more than once at a time
   --> $DIR/borrowck-mut-borrow-of-mut-base-ptr.rs:19:18
@@ -18,7 +18,7 @@ LL |     let mut t2 = &mut t0;
    |                  ^^^^^^^ second mutable borrow occurs here
 LL |     **t2 += 1;                  // Mutates `*t0` but not through `*p`
 LL |     p.use_mut();
-   |     - first borrow later used here
+   |     ----------- first borrow later used here
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/borrowck/borrowck-object-lifetime.nll.stderr b/src/test/ui/borrowck/borrowck-object-lifetime.nll.stderr
deleted file mode 100644
index 49c3f861ea9..00000000000
--- a/src/test/ui/borrowck/borrowck-object-lifetime.nll.stderr
+++ /dev/null
@@ -1,23 +0,0 @@
-error[E0502]: cannot borrow `*x` as mutable because it is also borrowed as immutable
-  --> $DIR/borrowck-object-lifetime.rs:20:13
-   |
-LL |     let y = x.borrowed();
-   |             - immutable borrow occurs here
-LL |     let z = x.mut_borrowed();
-   |             ^ mutable borrow occurs here
-LL |     y.use_ref();
-   |     - immutable borrow later used here
-
-error[E0502]: cannot borrow `x` as mutable because it is also borrowed as immutable
-  --> $DIR/borrowck-object-lifetime.rs:26:13
-   |
-LL |     let y = x.borrowed();
-   |             - immutable borrow occurs here
-LL |     let z = &mut x;
-   |             ^^^^^^ mutable borrow occurs here
-LL |     y.use_ref();
-   |     - immutable borrow later used here
-
-error: aborting due to 2 previous errors
-
-For more information about this error, try `rustc --explain E0502`.
diff --git a/src/test/ui/borrowck/borrowck-object-lifetime.stderr b/src/test/ui/borrowck/borrowck-object-lifetime.stderr
index cf94c74dec2..215ed760ae1 100644
--- a/src/test/ui/borrowck/borrowck-object-lifetime.stderr
+++ b/src/test/ui/borrowck/borrowck-object-lifetime.stderr
@@ -2,21 +2,21 @@ error[E0502]: cannot borrow `*x` as mutable because it is also borrowed as immut
   --> $DIR/borrowck-object-lifetime.rs:20:13
    |
 LL |     let y = x.borrowed();
-   |             - immutable borrow occurs here
+   |             ------------ immutable borrow occurs here
 LL |     let z = x.mut_borrowed();
    |             ^^^^^^^^^^^^^^^^ mutable borrow occurs here
 LL |     y.use_ref();
-   |     - immutable borrow later used here
+   |     ----------- immutable borrow later used here
 
 error[E0502]: cannot borrow `x` as mutable because it is also borrowed as immutable
   --> $DIR/borrowck-object-lifetime.rs:26:13
    |
 LL |     let y = x.borrowed();
-   |             - immutable borrow occurs here
+   |             ------------ immutable borrow occurs here
 LL |     let z = &mut x;
    |             ^^^^^^ mutable borrow occurs here
 LL |     y.use_ref();
-   |     - immutable borrow later used here
+   |     ----------- immutable borrow later used here
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/borrowck/borrowck-overloaded-index-autoderef.stderr b/src/test/ui/borrowck/borrowck-overloaded-index-autoderef.stderr
index 978e1291722..087f2ac799e 100644
--- a/src/test/ui/borrowck/borrowck-overloaded-index-autoderef.stderr
+++ b/src/test/ui/borrowck/borrowck-overloaded-index-autoderef.stderr
@@ -6,7 +6,7 @@ LL |     let p = &mut f[&s];
 LL |     let q = &f[&s];
    |              ^ immutable borrow occurs here
 LL |     p.use_mut();
-   |     - mutable borrow later used here
+   |     ----------- mutable borrow later used here
 
 error[E0499]: cannot borrow `*f` as mutable more than once at a time
   --> $DIR/borrowck-overloaded-index-autoderef.rs:43:18
@@ -16,7 +16,7 @@ LL |     let p = &mut f[&s];
 LL |     let q = &mut f[&s];
    |                  ^ second mutable borrow occurs here
 LL |     p.use_mut();
-   |     - first borrow later used here
+   |     ----------- first borrow later used here
 
 error[E0499]: cannot borrow `f.foo` as mutable more than once at a time
   --> $DIR/borrowck-overloaded-index-autoderef.rs:53:18
@@ -26,7 +26,7 @@ LL |     let p = &mut f.foo[&s];
 LL |     let q = &mut f.foo[&s];
    |                  ^^^^^ second mutable borrow occurs here
 LL |     p.use_mut();
-   |     - first borrow later used here
+   |     ----------- first borrow later used here
 
 error[E0502]: cannot borrow `f.foo` as mutable because it is also borrowed as immutable
   --> $DIR/borrowck-overloaded-index-autoderef.rs:65:18
@@ -36,7 +36,7 @@ LL |     let p = &f.foo[&s];
 LL |     let q = &mut f.foo[&s];
    |                  ^^^^^ mutable borrow occurs here
 LL |     p.use_ref();
-   |     - immutable borrow later used here
+   |     ----------- immutable borrow later used here
 
 error[E0506]: cannot assign to `f.foo` because it is borrowed
   --> $DIR/borrowck-overloaded-index-autoderef.rs:71:5
@@ -46,7 +46,7 @@ LL |     let p = &f.foo[&s];
 LL |     f.foo = g;
    |     ^^^^^^^^^ assignment to borrowed `f.foo` occurs here
 LL |     p.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error[E0506]: cannot assign to `*f` because it is borrowed
   --> $DIR/borrowck-overloaded-index-autoderef.rs:77:5
@@ -56,7 +56,7 @@ LL |     let p = &f.foo[&s];
 LL |     *f = g;
    |     ^^^^^^ assignment to borrowed `*f` occurs here
 LL |     p.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error[E0506]: cannot assign to `f.foo` because it is borrowed
   --> $DIR/borrowck-overloaded-index-autoderef.rs:83:5
@@ -66,7 +66,7 @@ LL |     let p = &mut f.foo[&s];
 LL |     f.foo = g;
    |     ^^^^^^^^^ assignment to borrowed `f.foo` occurs here
 LL |     p.use_mut();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error[E0506]: cannot assign to `*f` because it is borrowed
   --> $DIR/borrowck-overloaded-index-autoderef.rs:89:5
@@ -76,7 +76,7 @@ LL |     let p = &mut f.foo[&s];
 LL |     *f = g;
    |     ^^^^^^ assignment to borrowed `*f` occurs here
 LL |     p.use_mut();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error: aborting due to 8 previous errors
 
diff --git a/src/test/ui/borrowck/borrowck-report-with-custom-diagnostic.stderr b/src/test/ui/borrowck/borrowck-report-with-custom-diagnostic.stderr
index db73d4c04ac..d05996413dd 100644
--- a/src/test/ui/borrowck/borrowck-report-with-custom-diagnostic.stderr
+++ b/src/test/ui/borrowck/borrowck-report-with-custom-diagnostic.stderr
@@ -8,7 +8,7 @@ LL |     let z = &x;
    |             ^^ immutable borrow occurs here
 ...
 LL |     y.use_mut();
-   |     - mutable borrow later used here
+   |     ----------- mutable borrow later used here
 
 error[E0502]: cannot borrow `x` as mutable because it is also borrowed as immutable
   --> $DIR/borrowck-report-with-custom-diagnostic.rs:21:21
@@ -20,7 +20,7 @@ LL |             let z = &mut x;
    |                     ^^^^^^ mutable borrow occurs here
 ...
 LL |             y.use_ref();
-   |             - immutable borrow later used here
+   |             ----------- immutable borrow later used here
 
 error[E0499]: cannot borrow `x` as mutable more than once at a time
   --> $DIR/borrowck-report-with-custom-diagnostic.rs:36:17
@@ -32,7 +32,7 @@ LL |         let z = &mut x;
    |                 ^^^^^^ second mutable borrow occurs here
 ...
 LL |         y.use_mut();
-   |         - first borrow later used here
+   |         ----------- first borrow later used here
 
 error: aborting due to 3 previous errors
 
diff --git a/src/test/ui/borrowck/borrowck-swap-mut-base-ptr.stderr b/src/test/ui/borrowck/borrowck-swap-mut-base-ptr.stderr
index 1c55953c91f..b39215b9aab 100644
--- a/src/test/ui/borrowck/borrowck-swap-mut-base-ptr.stderr
+++ b/src/test/ui/borrowck/borrowck-swap-mut-base-ptr.stderr
@@ -7,7 +7,7 @@ LL |     swap(&mut t0, &mut t1);
    |          ^^^^^^^ mutable borrow occurs here
 LL |     *t1 = 22;
 LL |     p.use_ref();
-   |     - immutable borrow later used here
+   |     ----------- immutable borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/borrowck-union-borrow-nested.stderr b/src/test/ui/borrowck/borrowck-union-borrow-nested.stderr
index 61569b9cac1..4bd7d54cffe 100644
--- a/src/test/ui/borrowck/borrowck-union-borrow-nested.stderr
+++ b/src/test/ui/borrowck/borrowck-union-borrow-nested.stderr
@@ -6,7 +6,7 @@ LL |             let ra = &mut u.s.a;
 LL |             let b = u.c;
    |                     ^^^ use of borrowed `u.s.a`
 LL |             ra.use_mut();
-   |             -- borrow later used here
+   |             ------------ borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/borrowck-uniq-via-lend.stderr b/src/test/ui/borrowck/borrowck-uniq-via-lend.stderr
index 923edc8edae..6dbe4c74b58 100644
--- a/src/test/ui/borrowck/borrowck-uniq-via-lend.stderr
+++ b/src/test/ui/borrowck/borrowck-uniq-via-lend.stderr
@@ -6,7 +6,7 @@ LL |     let w = &mut v;
 LL |     borrow(&*v);
    |            ^^^ immutable borrow occurs here
 LL |     w.use_mut();
-   |     - mutable borrow later used here
+   |     ----------- mutable borrow later used here
 
 error[E0502]: cannot borrow `*v` as immutable because it is also borrowed as mutable
   --> $DIR/borrowck-uniq-via-lend.rs:53:12
@@ -16,7 +16,7 @@ LL |     x = &mut v;
 LL |     borrow(&*v);
    |            ^^^ immutable borrow occurs here
 LL |     x.use_mut();
-   |     - mutable borrow later used here
+   |     ----------- mutable borrow later used here
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/borrowck/borrowck-vec-pattern-loan-from-mut.stderr b/src/test/ui/borrowck/borrowck-vec-pattern-loan-from-mut.stderr
index 5141fcc1bb2..eb0f24b9b7a 100644
--- a/src/test/ui/borrowck/borrowck-vec-pattern-loan-from-mut.stderr
+++ b/src/test/ui/borrowck/borrowck-vec-pattern-loan-from-mut.stderr
@@ -5,8 +5,9 @@ LL |     let vb: &mut [isize] = &mut v;
    |                            ------ first mutable borrow occurs here
 ...
 LL |             v.push(tail[0] + tail[1]);
-   |             ^      ------- first borrow later used here
-   |             |
+   |             ^^^^^^^-------^^^^^^^^^^^
+   |             |      |
+   |             |      first borrow later used here
    |             second mutable borrow occurs here
 
 error: aborting due to previous error
diff --git a/src/test/ui/borrowck/borrowck-vec-pattern-nesting.stderr b/src/test/ui/borrowck/borrowck-vec-pattern-nesting.stderr
index 41c9b3be281..ddd89afe5bf 100644
--- a/src/test/ui/borrowck/borrowck-vec-pattern-nesting.stderr
+++ b/src/test/ui/borrowck/borrowck-vec-pattern-nesting.stderr
@@ -8,7 +8,7 @@ LL |             vec[0] = Box::new(4);
    |             ^^^^^^ assignment to borrowed `vec[_]` occurs here
 LL |
 LL |             _a.use_ref();
-   |             -- borrow later used here
+   |             ------------ borrow later used here
 
 error[E0506]: cannot assign to `vec[_]` because it is borrowed
   --> $DIR/borrowck-vec-pattern-nesting.rs:23:13
@@ -20,7 +20,7 @@ LL |             vec[0] = Box::new(4);
    |             ^^^^^^ assignment to borrowed `vec[_]` occurs here
 LL |
 LL |             _b.use_ref();
-   |             -- borrow later used here
+   |             ------------ borrow later used here
 
 error[E0508]: cannot move out of type `[Box<isize>]`, a non-copy slice
   --> $DIR/borrowck-vec-pattern-nesting.rs:34:11
diff --git a/src/test/ui/borrowck/index-mut-help-with-impl.stderr b/src/test/ui/borrowck/index-mut-help-with-impl.stderr
index 89391f4099a..69dca7e7b56 100644
--- a/src/test/ui/borrowck/index-mut-help-with-impl.stderr
+++ b/src/test/ui/borrowck/index-mut-help-with-impl.stderr
@@ -2,7 +2,7 @@ error[E0596]: cannot borrow data in a `&` reference as mutable
   --> $DIR/index-mut-help-with-impl.rs:9:5
    |
 LL |     Index::index(&v, 1..2).make_ascii_uppercase();
-   |     ^^^^^^^^^^^^^^^^^^^^^^ cannot borrow as mutable
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot borrow as mutable
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/index-mut-help.stderr b/src/test/ui/borrowck/index-mut-help.stderr
index 52b9ad496e5..057c6ee15f3 100644
--- a/src/test/ui/borrowck/index-mut-help.stderr
+++ b/src/test/ui/borrowck/index-mut-help.stderr
@@ -2,7 +2,7 @@ error[E0596]: cannot borrow data in an index of `HashMap<&str, String>` as mutab
   --> $DIR/index-mut-help.rs:11:5
    |
 LL |     map["peter"].clear();
-   |     ^^^^^^^^^^^^ cannot borrow as mutable
+   |     ^^^^^^^^^^^^^^^^^^^^ cannot borrow as mutable
    |
    = help: trait `IndexMut` is required to modify indexed content, but it is not implemented for `HashMap<&str, String>`
 
diff --git a/src/test/ui/borrowck/issue-42344.stderr b/src/test/ui/borrowck/issue-42344.stderr
index 5cffa1b5121..29b4c8c38d7 100644
--- a/src/test/ui/borrowck/issue-42344.stderr
+++ b/src/test/ui/borrowck/issue-42344.stderr
@@ -2,7 +2,7 @@ error[E0596]: cannot borrow `*TAB[_]` as mutable, as `TAB` is an immutable stati
   --> $DIR/issue-42344.rs:4:5
    |
 LL |     TAB[0].iter_mut();
-   |     ^^^^^^ cannot borrow as mutable
+   |     ^^^^^^^^^^^^^^^^^ cannot borrow as mutable
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/issue-51117.stderr b/src/test/ui/borrowck/issue-51117.stderr
index f8a9608ad37..ef1a16ea953 100644
--- a/src/test/ui/borrowck/issue-51117.stderr
+++ b/src/test/ui/borrowck/issue-51117.stderr
@@ -4,7 +4,7 @@ error[E0499]: cannot borrow `*bar` as mutable more than once at a time
 LL |         Some(baz) => {
    |              --- first mutable borrow occurs here
 LL |             bar.take();
-   |             ^^^ second mutable borrow occurs here
+   |             ^^^^^^^^^^ second mutable borrow occurs here
 LL |             drop(baz);
    |                  --- first borrow later used here
 
diff --git a/src/test/ui/borrowck/issue-81365-10.stderr b/src/test/ui/borrowck/issue-81365-10.stderr
index 891f70ed7f6..27123ef2be1 100644
--- a/src/test/ui/borrowck/issue-81365-10.stderr
+++ b/src/test/ui/borrowck/issue-81365-10.stderr
@@ -2,7 +2,7 @@ error[E0506]: cannot assign to `self.container_field` because it is borrowed
   --> $DIR/issue-81365-10.rs:21:9
    |
 LL |         let first = &self.deref().target_field;
-   |                      ---- borrow of `self.container_field` occurs here
+   |                      ------------ borrow of `self.container_field` occurs here
 LL |         self.container_field = true;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^ assignment to borrowed `self.container_field` occurs here
 LL |         first;
diff --git a/src/test/ui/borrowck/issue-81365-5.stderr b/src/test/ui/borrowck/issue-81365-5.stderr
index 7c0e9f43bd0..8201894c6db 100644
--- a/src/test/ui/borrowck/issue-81365-5.stderr
+++ b/src/test/ui/borrowck/issue-81365-5.stderr
@@ -2,7 +2,7 @@ error[E0506]: cannot assign to `self.container_field` because it is borrowed
   --> $DIR/issue-81365-5.rs:28:9
    |
 LL |         let first = self.get();
-   |                     ---- borrow of `self.container_field` occurs here
+   |                     ---------- borrow of `self.container_field` occurs here
 LL |         self.container_field = true;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^ assignment to borrowed `self.container_field` occurs here
 LL |         first;
diff --git a/src/test/ui/borrowck/issue-82032.stderr b/src/test/ui/borrowck/issue-82032.stderr
index f272477a9f5..25f343117a3 100644
--- a/src/test/ui/borrowck/issue-82032.stderr
+++ b/src/test/ui/borrowck/issue-82032.stderr
@@ -7,7 +7,7 @@ LL |         for v in self.0.values() {
    |                  |      help: use mutable method: `values_mut()`
    |                  this iterator yields `&` references
 LL |             v.flush();
-   |             ^ `v` is a `&` reference, so the data it refers to cannot be borrowed as mutable
+   |             ^^^^^^^^^ `v` is a `&` reference, so the data it refers to cannot be borrowed as mutable
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/issue-82462.nll.stderr b/src/test/ui/borrowck/issue-82462.nll.stderr
deleted file mode 100644
index 10497c30e64..00000000000
--- a/src/test/ui/borrowck/issue-82462.nll.stderr
+++ /dev/null
@@ -1,22 +0,0 @@
-error[E0502]: cannot borrow `v` as mutable because it is also borrowed as immutable
-  --> $DIR/issue-82462.rs:18:9
-   |
-LL |     for x in DroppingSlice(&*v).iter() {
-   |              ------------------
-   |              |               |
-   |              |               immutable borrow occurs here
-   |              a temporary with access to the immutable borrow is created here ...
-LL |         v.push(*x);
-   |         ^ mutable borrow occurs here
-LL |         break;
-LL |     }
-   |     - ... and the immutable borrow might be used here, when that temporary is dropped and runs the `Drop` code for type `DroppingSlice`
-   |
-help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped
-   |
-LL |     };
-   |      +
-
-error: aborting due to previous error
-
-For more information about this error, try `rustc --explain E0502`.
diff --git a/src/test/ui/borrowck/issue-85581.stderr b/src/test/ui/borrowck/issue-85581.stderr
index 29c0429f2a0..59ca4867fd7 100644
--- a/src/test/ui/borrowck/issue-85581.stderr
+++ b/src/test/ui/borrowck/issue-85581.stderr
@@ -7,7 +7,7 @@ LL |     match heap.peek_mut() {
    |           first mutable borrow occurs here
    |           a temporary with access to the first borrow is created here ...
 LL |         Some(_) => { heap.pop(); },
-   |                      ^^^^ second mutable borrow occurs here
+   |                      ^^^^^^^^^^ second mutable borrow occurs here
 ...
 LL | }
    | - ... and the first borrow might be used here, when that temporary is dropped and runs the destructor for type `Option<PeekMut<'_, i32>>`
diff --git a/src/test/ui/borrowck/issue-85765.stderr b/src/test/ui/borrowck/issue-85765.stderr
index af83c6ea6d9..80acaa7d21c 100644
--- a/src/test/ui/borrowck/issue-85765.stderr
+++ b/src/test/ui/borrowck/issue-85765.stderr
@@ -5,7 +5,7 @@ LL |     let rofl: &Vec<Vec<i32>> = &mut test;
    |         ---- help: consider changing this to be a mutable reference: `&mut Vec<Vec<i32>>`
 LL |
 LL |     rofl.push(Vec::new());
-   |     ^^^^ `rofl` is a `&` reference, so the data it refers to cannot be borrowed as mutable
+   |     ^^^^^^^^^^^^^^^^^^^^^ `rofl` is a `&` reference, so the data it refers to cannot be borrowed as mutable
 
 error[E0594]: cannot assign to `*r`, which is behind a `&` reference
   --> $DIR/issue-85765.rs:12:5
diff --git a/src/test/ui/borrowck/mut-borrow-of-mut-ref.stderr b/src/test/ui/borrowck/mut-borrow-of-mut-ref.stderr
index e4c51bb77c9..2ffe7ff6413 100644
--- a/src/test/ui/borrowck/mut-borrow-of-mut-ref.stderr
+++ b/src/test/ui/borrowck/mut-borrow-of-mut-ref.stderr
@@ -53,7 +53,7 @@ error[E0596]: cannot borrow `f` as mutable, as it is not declared as mutable
   --> $DIR/mut-borrow-of-mut-ref.rs:35:5
    |
 LL |     f.bar();
-   |     ^ cannot borrow as mutable
+   |     ^^^^^^^ cannot borrow as mutable
    |
 help: consider making the binding mutable
    |
diff --git a/src/test/ui/borrowck/mut-borrow-outside-loop.stderr b/src/test/ui/borrowck/mut-borrow-outside-loop.stderr
index 4fcb693f1bf..e6895b27f35 100644
--- a/src/test/ui/borrowck/mut-borrow-outside-loop.stderr
+++ b/src/test/ui/borrowck/mut-borrow-outside-loop.stderr
@@ -6,7 +6,7 @@ LL |     let first = &mut void;
 LL |     let second = &mut void;
    |                  ^^^^^^^^^ second mutable borrow occurs here
 LL |     first.use_mut();
-   |     ----- first borrow later used here
+   |     --------------- first borrow later used here
 
 error[E0499]: cannot borrow `inner_void` as mutable more than once at a time
   --> $DIR/mut-borrow-outside-loop.rs:15:28
@@ -17,7 +17,7 @@ LL |         let inner_second = &mut inner_void;
    |                            ^^^^^^^^^^^^^^^ second mutable borrow occurs here
 LL |         inner_second.use_mut();
 LL |         inner_first.use_mut();
-   |         ----------- first borrow later used here
+   |         --------------------- first borrow later used here
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/borrowck/two-phase-across-loop.stderr b/src/test/ui/borrowck/two-phase-across-loop.stderr
index d4e515d12bb..95896c6bbf9 100644
--- a/src/test/ui/borrowck/two-phase-across-loop.stderr
+++ b/src/test/ui/borrowck/two-phase-across-loop.stderr
@@ -2,7 +2,7 @@ error[E0499]: cannot borrow `foo` as mutable more than once at a time
   --> $DIR/two-phase-across-loop.rs:17:22
    |
 LL |         strings.push(foo.get_string());
-   |                      ^^^ `foo` was mutably borrowed here in the previous iteration of the loop
+   |                      ^^^^^^^^^^^^^^^^ `foo` was mutably borrowed here in the previous iteration of the loop
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/two-phase-cannot-nest-mut-self-calls.stderr b/src/test/ui/borrowck/two-phase-cannot-nest-mut-self-calls.stderr
index 9bfd8b994bf..a89bb941532 100644
--- a/src/test/ui/borrowck/two-phase-cannot-nest-mut-self-calls.stderr
+++ b/src/test/ui/borrowck/two-phase-cannot-nest-mut-self-calls.stderr
@@ -1,13 +1,18 @@
 error[E0502]: cannot borrow `vec` as mutable because it is also borrowed as immutable
   --> $DIR/two-phase-cannot-nest-mut-self-calls.rs:16:9
    |
-LL |     vec.get({
-   |     --- --- immutable borrow later used by call
-   |     |
-   |     immutable borrow occurs here
-LL | 
-LL |         vec.push(2);
-   |         ^^^ mutable borrow occurs here
+LL |       vec.get({
+   |       -   --- immutable borrow later used by call
+   |  _____|
+   | |
+LL | |
+LL | |         vec.push(2);
+   | |         ^^^^^^^^^^^ mutable borrow occurs here
+LL | |
+LL | |
+LL | |         0
+LL | |     });
+   | |______- immutable borrow occurs here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/two-phase-multi-mut.stderr b/src/test/ui/borrowck/two-phase-multi-mut.stderr
index 33fa4a3a150..2e53e17a31b 100644
--- a/src/test/ui/borrowck/two-phase-multi-mut.stderr
+++ b/src/test/ui/borrowck/two-phase-multi-mut.stderr
@@ -12,8 +12,9 @@ error[E0499]: cannot borrow `foo` as mutable more than once at a time
   --> $DIR/two-phase-multi-mut.rs:11:16
    |
 LL |     foo.method(&mut foo);
-   |     --- ------ ^^^^^^^^ second mutable borrow occurs here
-   |     |   |
+   |     -----------^^^^^^^^-
+   |     |   |      |
+   |     |   |      second mutable borrow occurs here
    |     |   first borrow later used by call
    |     first mutable borrow occurs here
 
diff --git a/src/test/ui/borrowck/two-phase-reservation-sharing-interference-2.migrate2015.stderr b/src/test/ui/borrowck/two-phase-reservation-sharing-interference-2.migrate2015.stderr
index e4fceb197be..6cff53399ca 100644
--- a/src/test/ui/borrowck/two-phase-reservation-sharing-interference-2.migrate2015.stderr
+++ b/src/test/ui/borrowck/two-phase-reservation-sharing-interference-2.migrate2015.stderr
@@ -27,8 +27,9 @@ LL |     let shared = &v;
    |                  -- immutable borrow occurs here
 LL | 
 LL |     v.push(shared.len());
-   |     ^      ------ immutable borrow later used here
-   |     |
+   |     ^^^^^^^------------^
+   |     |      |
+   |     |      immutable borrow later used here
    |     mutable borrow occurs here
    |
    = note: `#[warn(mutable_borrow_reservation_conflict)]` on by default
diff --git a/src/test/ui/borrowck/two-phase-reservation-sharing-interference-2.migrate2018.stderr b/src/test/ui/borrowck/two-phase-reservation-sharing-interference-2.migrate2018.stderr
index e4fceb197be..6cff53399ca 100644
--- a/src/test/ui/borrowck/two-phase-reservation-sharing-interference-2.migrate2018.stderr
+++ b/src/test/ui/borrowck/two-phase-reservation-sharing-interference-2.migrate2018.stderr
@@ -27,8 +27,9 @@ LL |     let shared = &v;
    |                  -- immutable borrow occurs here
 LL | 
 LL |     v.push(shared.len());
-   |     ^      ------ immutable borrow later used here
-   |     |
+   |     ^^^^^^^------------^
+   |     |      |
+   |     |      immutable borrow later used here
    |     mutable borrow occurs here
    |
    = note: `#[warn(mutable_borrow_reservation_conflict)]` on by default
diff --git a/src/test/ui/borrowck/two-phase-reservation-sharing-interference-2.nll2015.stderr b/src/test/ui/borrowck/two-phase-reservation-sharing-interference-2.nll2015.stderr
index 52017394e89..0ae6fe78c6a 100644
--- a/src/test/ui/borrowck/two-phase-reservation-sharing-interference-2.nll2015.stderr
+++ b/src/test/ui/borrowck/two-phase-reservation-sharing-interference-2.nll2015.stderr
@@ -5,8 +5,9 @@ LL |     let shared = &v;
    |                  -- immutable borrow occurs here
 LL | 
 LL |     v.extend(shared);
-   |     ^        ------ immutable borrow later used here
-   |     |
+   |     ^^^^^^^^^------^
+   |     |        |
+   |     |        immutable borrow later used here
    |     mutable borrow occurs here
 
 error[E0502]: cannot borrow `v` as mutable because it is also borrowed as immutable
@@ -26,8 +27,9 @@ LL |     let shared = &v;
    |                  -- immutable borrow occurs here
 LL | 
 LL |     v.push(shared.len());
-   |     ^      ------ immutable borrow later used here
-   |     |
+   |     ^^^^^^^------------^
+   |     |      |
+   |     |      immutable borrow later used here
    |     mutable borrow occurs here
 
 error: aborting due to 3 previous errors
diff --git a/src/test/ui/borrowck/two-phase-reservation-sharing-interference-2.nll2018.stderr b/src/test/ui/borrowck/two-phase-reservation-sharing-interference-2.nll2018.stderr
index 52017394e89..0ae6fe78c6a 100644
--- a/src/test/ui/borrowck/two-phase-reservation-sharing-interference-2.nll2018.stderr
+++ b/src/test/ui/borrowck/two-phase-reservation-sharing-interference-2.nll2018.stderr
@@ -5,8 +5,9 @@ LL |     let shared = &v;
    |                  -- immutable borrow occurs here
 LL | 
 LL |     v.extend(shared);
-   |     ^        ------ immutable borrow later used here
-   |     |
+   |     ^^^^^^^^^------^
+   |     |        |
+   |     |        immutable borrow later used here
    |     mutable borrow occurs here
 
 error[E0502]: cannot borrow `v` as mutable because it is also borrowed as immutable
@@ -26,8 +27,9 @@ LL |     let shared = &v;
    |                  -- immutable borrow occurs here
 LL | 
 LL |     v.push(shared.len());
-   |     ^      ------ immutable borrow later used here
-   |     |
+   |     ^^^^^^^------------^
+   |     |      |
+   |     |      immutable borrow later used here
    |     mutable borrow occurs here
 
 error: aborting due to 3 previous errors
diff --git a/src/test/ui/borrowck/two-phase-reservation-sharing-interference-future-compat-lint.nll.stderr b/src/test/ui/borrowck/two-phase-reservation-sharing-interference-future-compat-lint.nll.stderr
index d2ea5ab2077..52e8de3c4ac 100644
--- a/src/test/ui/borrowck/two-phase-reservation-sharing-interference-future-compat-lint.nll.stderr
+++ b/src/test/ui/borrowck/two-phase-reservation-sharing-interference-future-compat-lint.nll.stderr
@@ -5,8 +5,9 @@ LL |         let shared = &v;
    |                      -- immutable borrow occurs here
 LL | 
 LL |         v.push(shared.len());
-   |         ^      ------ immutable borrow later used here
-   |         |
+   |         ^^^^^^^------------^
+   |         |      |
+   |         |      immutable borrow later used here
    |         mutable borrow occurs here
 
 error[E0502]: cannot borrow `v` as mutable because it is also borrowed as immutable
@@ -16,8 +17,9 @@ LL |         let shared = &v;
    |                      -- immutable borrow occurs here
 LL | 
 LL |         v.push(shared.len());
-   |         ^      ------ immutable borrow later used here
-   |         |
+   |         ^^^^^^^------------^
+   |         |      |
+   |         |      immutable borrow later used here
    |         mutable borrow occurs here
 
 error[E0502]: cannot borrow `v` as mutable because it is also borrowed as immutable
@@ -27,8 +29,9 @@ LL |         let shared = &v;
    |                      -- immutable borrow occurs here
 LL | 
 LL |         v.push(shared.len());
-   |         ^      ------ immutable borrow later used here
-   |         |
+   |         ^^^^^^^------------^
+   |         |      |
+   |         |      immutable borrow later used here
    |         mutable borrow occurs here
 
 error: aborting due to 3 previous errors
diff --git a/src/test/ui/borrowck/two-phase-reservation-sharing-interference-future-compat-lint.stderr b/src/test/ui/borrowck/two-phase-reservation-sharing-interference-future-compat-lint.stderr
index 03f49d2d92f..aab21c9e78b 100644
--- a/src/test/ui/borrowck/two-phase-reservation-sharing-interference-future-compat-lint.stderr
+++ b/src/test/ui/borrowck/two-phase-reservation-sharing-interference-future-compat-lint.stderr
@@ -5,8 +5,9 @@ LL |         let shared = &v;
    |                      -- immutable borrow occurs here
 LL | 
 LL |         v.push(shared.len());
-   |         ^      ------ immutable borrow later used here
-   |         |
+   |         ^^^^^^^------------^
+   |         |      |
+   |         |      immutable borrow later used here
    |         mutable borrow occurs here
    |
 note: the lint level is defined here
@@ -24,8 +25,9 @@ LL |         let shared = &v;
    |                      -- immutable borrow occurs here
 LL | 
 LL |         v.push(shared.len());
-   |         ^      ------ immutable borrow later used here
-   |         |
+   |         ^^^^^^^------------^
+   |         |      |
+   |         |      immutable borrow later used here
    |         mutable borrow occurs here
    |
 note: the lint level is defined here
diff --git a/src/test/ui/borrowck/two-phase-sneaky.stderr b/src/test/ui/borrowck/two-phase-sneaky.stderr
index c66f3cbed91..cffbf0706fe 100644
--- a/src/test/ui/borrowck/two-phase-sneaky.stderr
+++ b/src/test/ui/borrowck/two-phase-sneaky.stderr
@@ -7,7 +7,7 @@ LL |     v[0].push_str({
    |     first mutable borrow occurs here
 LL | 
 LL |         v.push(format!("foo"));
-   |         ^ second mutable borrow occurs here
+   |         ^^^^^^^^^^^^^^^^^^^^^^ second mutable borrow occurs here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/two-phase-surprise-no-conflict.stderr b/src/test/ui/borrowck/two-phase-surprise-no-conflict.stderr
index 7d0e1566750..5a240d90011 100644
--- a/src/test/ui/borrowck/two-phase-surprise-no-conflict.stderr
+++ b/src/test/ui/borrowck/two-phase-surprise-no-conflict.stderr
@@ -13,7 +13,7 @@ error[E0502]: cannot borrow `*self` as mutable because it is also borrowed as im
   --> $DIR/two-phase-surprise-no-conflict.rs:57:17
    |
 LL |                 self.hash_expr(&self.cx_mut.body(eid).value);
-   |                 ^^^^^---------^^-----------^^^^^^^^^^^^^^^^^
+   |                 ^^^^^---------^^---------------------^^^^^^^
    |                 |    |          |
    |                 |    |          immutable borrow occurs here
    |                 |    immutable borrow later used by call
@@ -23,8 +23,9 @@ error[E0499]: cannot borrow `reg.sess_mut` as mutable more than once at a time
   --> $DIR/two-phase-surprise-no-conflict.rs:119:51
    |
 LL |     reg.register_static(Box::new(TrivialPass::new(&mut reg.sess_mut)));
-   |     --- ---------------                           ^^^^^^^^^^^^^^^^^ second mutable borrow occurs here
-   |     |   |
+   |     ----------------------------------------------^^^^^^^^^^^^^^^^^---
+   |     |   |                                         |
+   |     |   |                                         second mutable borrow occurs here
    |     |   first borrow later used by call
    |     first mutable borrow occurs here
 
@@ -32,8 +33,9 @@ error[E0499]: cannot borrow `reg.sess_mut` as mutable more than once at a time
   --> $DIR/two-phase-surprise-no-conflict.rs:122:54
    |
 LL |     reg.register_bound(Box::new(TrivialPass::new_mut(&mut reg.sess_mut)));
-   |     --- --------------                               ^^^^^^^^^^^^^^^^^ second mutable borrow occurs here
-   |     |   |
+   |     -------------------------------------------------^^^^^^^^^^^^^^^^^---
+   |     |   |                                            |
+   |     |   |                                            second mutable borrow occurs here
    |     |   first borrow later used by call
    |     first mutable borrow occurs here
 
@@ -41,8 +43,9 @@ error[E0499]: cannot borrow `reg.sess_mut` as mutable more than once at a time
   --> $DIR/two-phase-surprise-no-conflict.rs:125:53
    |
 LL |     reg.register_univ(Box::new(TrivialPass::new_mut(&mut reg.sess_mut)));
-   |     --- -------------                               ^^^^^^^^^^^^^^^^^ second mutable borrow occurs here
-   |     |   |
+   |     ------------------------------------------------^^^^^^^^^^^^^^^^^---
+   |     |   |                                           |
+   |     |   |                                           second mutable borrow occurs here
    |     |   first borrow later used by call
    |     first mutable borrow occurs here
 
@@ -50,8 +53,9 @@ error[E0499]: cannot borrow `reg.sess_mut` as mutable more than once at a time
   --> $DIR/two-phase-surprise-no-conflict.rs:128:44
    |
 LL |     reg.register_ref(&TrivialPass::new_mut(&mut reg.sess_mut));
-   |     --- ------------                       ^^^^^^^^^^^^^^^^^ second mutable borrow occurs here
-   |     |   |
+   |     ---------------------------------------^^^^^^^^^^^^^^^^^--
+   |     |   |                                  |
+   |     |   |                                  second mutable borrow occurs here
    |     |   first borrow later used by call
    |     first mutable borrow occurs here
 
@@ -102,8 +106,9 @@ error[E0499]: cannot borrow `reg.sess_mut` as mutable more than once at a time
   --> $DIR/two-phase-surprise-no-conflict.rs:154:54
    |
 LL |     reg.register_bound(Box::new(CapturePass::new_mut(&mut reg.sess_mut)));
-   |     --- --------------                               ^^^^^^^^^^^^^^^^^ second mutable borrow occurs here
-   |     |   |
+   |     -------------------------------------------------^^^^^^^^^^^^^^^^^---
+   |     |   |                                            |
+   |     |   |                                            second mutable borrow occurs here
    |     |   first borrow later used by call
    |     first mutable borrow occurs here
 
@@ -124,8 +129,9 @@ error[E0499]: cannot borrow `reg.sess_mut` as mutable more than once at a time
   --> $DIR/two-phase-surprise-no-conflict.rs:158:53
    |
 LL |     reg.register_univ(Box::new(CapturePass::new_mut(&mut reg.sess_mut)));
-   |     --- -------------                               ^^^^^^^^^^^^^^^^^ second mutable borrow occurs here
-   |     |   |
+   |     ------------------------------------------------^^^^^^^^^^^^^^^^^---
+   |     |   |                                           |
+   |     |   |                                           second mutable borrow occurs here
    |     |   first borrow later used by call
    |     first mutable borrow occurs here
 
@@ -143,8 +149,9 @@ error[E0499]: cannot borrow `reg.sess_mut` as mutable more than once at a time
   --> $DIR/two-phase-surprise-no-conflict.rs:162:44
    |
 LL |     reg.register_ref(&CapturePass::new_mut(&mut reg.sess_mut));
-   |     --- ------------                       ^^^^^^^^^^^^^^^^^ second mutable borrow occurs here
-   |     |   |
+   |     ---------------------------------------^^^^^^^^^^^^^^^^^--
+   |     |   |                                  |
+   |     |   |                                  second mutable borrow occurs here
    |     |   first borrow later used by call
    |     first mutable borrow occurs here
 
diff --git a/src/test/ui/box/leak-alloc.stderr b/src/test/ui/box/leak-alloc.stderr
index 09beb181460..e8a6ad0995a 100644
--- a/src/test/ui/box/leak-alloc.stderr
+++ b/src/test/ui/box/leak-alloc.stderr
@@ -2,7 +2,7 @@ error[E0505]: cannot move out of `alloc` because it is borrowed
   --> $DIR/leak-alloc.rs:26:10
    |
 LL |     let boxed = Box::new_in(10, alloc.by_ref());
-   |                                 ----- borrow of `alloc` occurs here
+   |                                 -------------- borrow of `alloc` occurs here
 LL |     let theref = Box::leak(boxed);
 LL |     drop(alloc);
    |          ^^^^^ move out of `alloc` occurs here
diff --git a/src/test/ui/cannot-mutate-captured-non-mut-var.stderr b/src/test/ui/cannot-mutate-captured-non-mut-var.stderr
index 2d6e83c9e82..06b5ca407db 100644
--- a/src/test/ui/cannot-mutate-captured-non-mut-var.stderr
+++ b/src/test/ui/cannot-mutate-captured-non-mut-var.stderr
@@ -12,7 +12,7 @@ error[E0596]: cannot borrow `s` as mutable, as it is not declared as mutable
 LL |     let s = std::io::stdin();
    |         - help: consider changing this to be mutable: `mut s`
 LL |     to_fn_once(move|| { s.read_to_end(&mut Vec::new()); });
-   |                         ^ cannot borrow as mutable
+   |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot borrow as mutable
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/closures/2229_closure_analysis/issue-88118-2.rs b/src/test/ui/closures/2229_closure_analysis/issue-88118-2.rs
new file mode 100644
index 00000000000..0cfb1a55bf2
--- /dev/null
+++ b/src/test/ui/closures/2229_closure_analysis/issue-88118-2.rs
@@ -0,0 +1,24 @@
+// edition:2021
+// run-pass
+#![feature(if_let_guard)]
+#[allow(unused_must_use)]
+#[allow(dead_code)]
+
+fn print_error_count(registry: &Registry) {
+    |x: &Registry| {
+        match &x {
+            Registry if let _ = registry.try_find_description() => { }
+            //~^ WARNING: irrefutable `if let` guard pattern
+            _ => {}
+        }
+    };
+}
+
+struct Registry;
+impl Registry {
+    pub fn try_find_description(&self) {
+        unimplemented!()
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/closures/2229_closure_analysis/issue-88118-2.stderr b/src/test/ui/closures/2229_closure_analysis/issue-88118-2.stderr
new file mode 100644
index 00000000000..15689023d81
--- /dev/null
+++ b/src/test/ui/closures/2229_closure_analysis/issue-88118-2.stderr
@@ -0,0 +1,12 @@
+warning: irrefutable `if let` guard pattern
+  --> $DIR/issue-88118-2.rs:10:29
+   |
+LL |             Registry if let _ = registry.try_find_description() => { }
+   |                             ^
+   |
+   = note: `#[warn(irrefutable_let_patterns)]` on by default
+   = note: this pattern will always match, so the guard is useless
+   = help: consider removing the guard and adding a `let` inside the match arm
+
+warning: 1 warning emitted
+
diff --git a/src/test/ui/codemap_tests/issue-11715.stderr b/src/test/ui/codemap_tests/issue-11715.stderr
index d0c29c768eb..a6b2b2e50a3 100644
--- a/src/test/ui/codemap_tests/issue-11715.stderr
+++ b/src/test/ui/codemap_tests/issue-11715.stderr
@@ -7,7 +7,7 @@ LL |     let z = &mut x;
    |             ^^^^^^ second mutable borrow occurs here
 LL |     z.use_mut();
 LL |     y.use_mut();
-   |     - first borrow later used here
+   |     ----------- first borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/codemap_tests/one_line.stderr b/src/test/ui/codemap_tests/one_line.stderr
index eddbd29c0ef..1ee612184de 100644
--- a/src/test/ui/codemap_tests/one_line.stderr
+++ b/src/test/ui/codemap_tests/one_line.stderr
@@ -2,8 +2,9 @@ error[E0499]: cannot borrow `v` as mutable more than once at a time
   --> $DIR/one_line.rs:3:12
    |
 LL |     v.push(v.pop().unwrap());
-   |     - ---- ^ second mutable borrow occurs here
-   |     | |
+   |     -------^^^^^^^----------
+   |     | |    |
+   |     | |    second mutable borrow occurs here
    |     | first borrow later used by call
    |     first mutable borrow occurs here
 
diff --git a/src/test/ui/const-generics/issues/issue-67375.full.stderr b/src/test/ui/const-generics/issues/issue-67375.full.stderr
index d7b52063dc4..8c9672fd7fc 100644
--- a/src/test/ui/const-generics/issues/issue-67375.full.stderr
+++ b/src/test/ui/const-generics/issues/issue-67375.full.stderr
@@ -2,7 +2,7 @@ error: overly complex generic constant
   --> $DIR/issue-67375.rs:7:17
    |
 LL |     inner: [(); { [|_: &T| {}; 0].len() }],
-   |                 ^^---------------^^^^^^^^
+   |                 ^^---------------------^^
    |                   |
    |                   unsupported operation in generic constant
    |
diff --git a/src/test/ui/const-generics/parser-error-recovery/issue-89013-no-assoc.rs b/src/test/ui/const-generics/parser-error-recovery/issue-89013-no-assoc.rs
new file mode 100644
index 00000000000..99d8e9dea91
--- /dev/null
+++ b/src/test/ui/const-generics/parser-error-recovery/issue-89013-no-assoc.rs
@@ -0,0 +1,16 @@
+trait Foo<const N: usize> {
+    fn do_x(&self) -> [u8; N];
+}
+
+struct Bar;
+
+const T: usize = 42;
+
+impl Foo<const 3> for Bar {
+//~^ERROR expected lifetime, type, or constant, found keyword `const`
+    fn do_x(&self) -> [u8; 3] {
+        [0u8; 3]
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/const-generics/parser-error-recovery/issue-89013-no-assoc.stderr b/src/test/ui/const-generics/parser-error-recovery/issue-89013-no-assoc.stderr
new file mode 100644
index 00000000000..ddddd86ab9c
--- /dev/null
+++ b/src/test/ui/const-generics/parser-error-recovery/issue-89013-no-assoc.stderr
@@ -0,0 +1,14 @@
+error: expected lifetime, type, or constant, found keyword `const`
+  --> $DIR/issue-89013-no-assoc.rs:9:10
+   |
+LL | impl Foo<const 3> for Bar {
+   |          ^^^^^
+   |
+help: the `const` keyword is only needed in the definition of the type
+   |
+LL - impl Foo<const 3> for Bar {
+LL + impl Foo<3> for Bar {
+   | 
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/const-generics/parser-error-recovery/issue-89013-no-kw.rs b/src/test/ui/const-generics/parser-error-recovery/issue-89013-no-kw.rs
new file mode 100644
index 00000000000..19e0f38d320
--- /dev/null
+++ b/src/test/ui/const-generics/parser-error-recovery/issue-89013-no-kw.rs
@@ -0,0 +1,17 @@
+trait Foo<const N: usize> {
+    fn do_x(&self) -> [u8; N];
+}
+
+struct Bar;
+
+const T: usize = 42;
+
+impl Foo<N = 3> for Bar {
+//~^ ERROR cannot constrain an associated constant to a value
+//~| ERROR associated type bindings are not allowed here
+    fn do_x(&self) -> [u8; 3] {
+        [0u8; 3]
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/const-generics/parser-error-recovery/issue-89013-no-kw.stderr b/src/test/ui/const-generics/parser-error-recovery/issue-89013-no-kw.stderr
new file mode 100644
index 00000000000..bbca92ad63a
--- /dev/null
+++ b/src/test/ui/const-generics/parser-error-recovery/issue-89013-no-kw.stderr
@@ -0,0 +1,18 @@
+error: cannot constrain an associated constant to a value
+  --> $DIR/issue-89013-no-kw.rs:9:10
+   |
+LL | impl Foo<N = 3> for Bar {
+   |          -^^^-
+   |          |   |
+   |          |   ...cannot be constrained to this value
+   |          this associated constant...
+
+error[E0229]: associated type bindings are not allowed here
+  --> $DIR/issue-89013-no-kw.rs:9:10
+   |
+LL | impl Foo<N = 3> for Bar {
+   |          ^^^^^ associated type not allowed here
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0229`.
diff --git a/src/test/ui/const-generics/parser-error-recovery/issue-89013-type.rs b/src/test/ui/const-generics/parser-error-recovery/issue-89013-type.rs
new file mode 100644
index 00000000000..0ec6762b6e2
--- /dev/null
+++ b/src/test/ui/const-generics/parser-error-recovery/issue-89013-type.rs
@@ -0,0 +1,16 @@
+trait Foo<const N: usize> {
+    fn do_x(&self) -> [u8; N];
+}
+
+struct Bar;
+
+const T: usize = 42;
+
+impl Foo<N = type 3> for Bar {
+//~^ERROR missing type to the right of `=`
+    fn do_x(&self) -> [u8; 3] {
+        [0u8; 3]
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/const-generics/parser-error-recovery/issue-89013-type.stderr b/src/test/ui/const-generics/parser-error-recovery/issue-89013-type.stderr
new file mode 100644
index 00000000000..f0d0d90c774
--- /dev/null
+++ b/src/test/ui/const-generics/parser-error-recovery/issue-89013-type.stderr
@@ -0,0 +1,8 @@
+error: missing type to the right of `=`
+  --> $DIR/issue-89013-type.rs:9:13
+   |
+LL | impl Foo<N = type 3> for Bar {
+   |             ^---- expected type, found keyword `type`
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/const-generics/parser-error-recovery/issue-89013.rs b/src/test/ui/const-generics/parser-error-recovery/issue-89013.rs
new file mode 100644
index 00000000000..ca1158a2f6d
--- /dev/null
+++ b/src/test/ui/const-generics/parser-error-recovery/issue-89013.rs
@@ -0,0 +1,18 @@
+trait Foo<const N: usize> {
+    fn do_x(&self) -> [u8; N];
+}
+
+struct Bar;
+
+const T: usize = 42;
+
+impl Foo<N = const 3> for Bar {
+//~^ ERROR expected lifetime, type, or constant, found keyword `const`
+//~| ERROR cannot constrain an associated constant to a value
+//~| ERROR associated type bindings are not allowed here
+    fn do_x(&self) -> [u8; 3] {
+        [0u8; 3]
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/const-generics/parser-error-recovery/issue-89013.stderr b/src/test/ui/const-generics/parser-error-recovery/issue-89013.stderr
new file mode 100644
index 00000000000..85379d3f06e
--- /dev/null
+++ b/src/test/ui/const-generics/parser-error-recovery/issue-89013.stderr
@@ -0,0 +1,30 @@
+error: expected lifetime, type, or constant, found keyword `const`
+  --> $DIR/issue-89013.rs:9:14
+   |
+LL | impl Foo<N = const 3> for Bar {
+   |              ^^^^^
+   |
+help: the `const` keyword is only needed in the definition of the type
+   |
+LL - impl Foo<N = const 3> for Bar {
+LL + impl Foo<N = 3> for Bar {
+   | 
+
+error: cannot constrain an associated constant to a value
+  --> $DIR/issue-89013.rs:9:10
+   |
+LL | impl Foo<N = const 3> for Bar {
+   |          -^^^^^^^^^-
+   |          |         |
+   |          |         ...cannot be constrained to this value
+   |          this associated constant...
+
+error[E0229]: associated type bindings are not allowed here
+  --> $DIR/issue-89013.rs:9:10
+   |
+LL | impl Foo<N = const 3> for Bar {
+   |          ^^^^^^^^^^^ associated type not allowed here
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0229`.
diff --git a/src/test/ui/consts/const_in_pattern/issue-78057.stderr b/src/test/ui/consts/const_in_pattern/issue-78057.stderr
index 0d49d0e96c8..35619594f75 100644
--- a/src/test/ui/consts/const_in_pattern/issue-78057.stderr
+++ b/src/test/ui/consts/const_in_pattern/issue-78057.stderr
@@ -7,8 +7,11 @@ LL |         FOO => {},
 error: unreachable pattern
   --> $DIR/issue-78057.rs:14:9
    |
+LL |         FOO => {},
+   |         --- matches any value
+LL |
 LL |         _ => {}
-   |         ^
+   |         ^ unreachable pattern
    |
 note: the lint level is defined here
   --> $DIR/issue-78057.rs:1:9
diff --git a/src/test/ui/consts/const_let_assign3.stderr b/src/test/ui/consts/const_let_assign3.stderr
index 89073f975e8..b550ac54573 100644
--- a/src/test/ui/consts/const_let_assign3.stderr
+++ b/src/test/ui/consts/const_let_assign3.stderr
@@ -11,7 +11,7 @@ error[E0658]: mutable references are not allowed in constants
   --> $DIR/const_let_assign3.rs:14:5
    |
 LL |     s.foo(3);
-   |     ^
+   |     ^^^^^^^^
    |
    = note: see issue #57349 <https://github.com/rust-lang/rust/issues/57349> for more information
    = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
diff --git a/src/test/ui/consts/try-operator.rs b/src/test/ui/consts/try-operator.rs
new file mode 100644
index 00000000000..fe43b132cbd
--- /dev/null
+++ b/src/test/ui/consts/try-operator.rs
@@ -0,0 +1,23 @@
+// run-pass
+
+#![feature(try_trait_v2)]
+#![feature(const_trait_impl)]
+#![feature(const_try)]
+#![feature(const_convert)]
+
+fn main() {
+    const fn result() -> Result<bool, ()> {
+        Err(())?;
+        Ok(true)
+    }
+
+    const FOO: Result<bool, ()> = result();
+    assert_eq!(Err(()), FOO);
+
+    const fn option() -> Option<()> {
+        None?;
+        Some(())
+    }
+    const BAR: Option<()> = option();
+    assert_eq!(None, BAR);
+}
diff --git a/src/test/ui/did_you_mean/issue-34126.stderr b/src/test/ui/did_you_mean/issue-34126.stderr
index 666172197ce..0503fac4a66 100644
--- a/src/test/ui/did_you_mean/issue-34126.stderr
+++ b/src/test/ui/did_you_mean/issue-34126.stderr
@@ -19,8 +19,9 @@ error[E0502]: cannot borrow `self` as mutable because it is also borrowed as imm
   --> $DIR/issue-34126.rs:6:18
    |
 LL |         self.run(&mut self);
-   |         ---- --- ^^^^^^^^^ mutable borrow occurs here
-   |         |    |
+   |         ---------^^^^^^^^^-
+   |         |    |   |
+   |         |    |   mutable borrow occurs here
    |         |    immutable borrow later used by call
    |         immutable borrow occurs here
 
diff --git a/src/test/ui/did_you_mean/issue-35937.stderr b/src/test/ui/did_you_mean/issue-35937.stderr
index 1f578d18a1c..9562d94509e 100644
--- a/src/test/ui/did_you_mean/issue-35937.stderr
+++ b/src/test/ui/did_you_mean/issue-35937.stderr
@@ -4,7 +4,7 @@ error[E0596]: cannot borrow `f.v` as mutable, as `f` is not declared as mutable
 LL |     let f = Foo { v: Vec::new() };
    |         - help: consider changing this to be mutable: `mut f`
 LL |     f.v.push("cat".to_string());
-   |     ^^^ cannot borrow as mutable
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot borrow as mutable
 
 error[E0594]: cannot assign to `s.x`, as `s` is not declared as mutable
   --> $DIR/issue-35937.rs:16:5
diff --git a/src/test/ui/did_you_mean/issue-38147-1.stderr b/src/test/ui/did_you_mean/issue-38147-1.stderr
index 6efac371c02..dd193458b37 100644
--- a/src/test/ui/did_you_mean/issue-38147-1.stderr
+++ b/src/test/ui/did_you_mean/issue-38147-1.stderr
@@ -4,7 +4,7 @@ error[E0596]: cannot borrow `*self.s` as mutable, as it is behind a `&` referenc
 LL |     fn f(&self) {
    |          ----- help: consider changing this to be a mutable reference: `&mut self`
 LL |         self.s.push('x');
-   |         ^^^^^^ `self` is a `&` reference, so the data it refers to cannot be borrowed as mutable
+   |         ^^^^^^^^^^^^^^^^ `self` is a `&` reference, so the data it refers to cannot be borrowed as mutable
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/did_you_mean/issue-38147-2.stderr b/src/test/ui/did_you_mean/issue-38147-2.stderr
index cb498108931..8bf5c76977d 100644
--- a/src/test/ui/did_you_mean/issue-38147-2.stderr
+++ b/src/test/ui/did_you_mean/issue-38147-2.stderr
@@ -5,7 +5,7 @@ LL |     s: &'a String
    |        ---------- help: consider changing this to be mutable: `&'a mut String`
 ...
 LL |         self.s.push('x');
-   |         ^^^^^^ cannot borrow as mutable
+   |         ^^^^^^^^^^^^^^^^ cannot borrow as mutable
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/did_you_mean/issue-38147-3.stderr b/src/test/ui/did_you_mean/issue-38147-3.stderr
index 67782578a2c..0e1e42261c4 100644
--- a/src/test/ui/did_you_mean/issue-38147-3.stderr
+++ b/src/test/ui/did_you_mean/issue-38147-3.stderr
@@ -5,7 +5,7 @@ LL |     s: &'a String
    |        ---------- help: consider changing this to be mutable: `&'a mut String`
 ...
 LL |         self.s.push('x');
-   |         ^^^^^^ cannot borrow as mutable
+   |         ^^^^^^^^^^^^^^^^ cannot borrow as mutable
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/did_you_mean/issue-38147-4.stderr b/src/test/ui/did_you_mean/issue-38147-4.stderr
index db3e6b89426..a2d162f08a1 100644
--- a/src/test/ui/did_you_mean/issue-38147-4.stderr
+++ b/src/test/ui/did_you_mean/issue-38147-4.stderr
@@ -4,7 +4,7 @@ error[E0596]: cannot borrow `*f.s` as mutable, as it is behind a `&` reference
 LL | fn f(x: usize, f: &Foo) {
    |                   ---- help: consider changing this to be a mutable reference: `&mut Foo<'_>`
 LL |     f.s.push('x');
-   |     ^^^ `f` is a `&` reference, so the data it refers to cannot be borrowed as mutable
+   |     ^^^^^^^^^^^^^ `f` is a `&` reference, so the data it refers to cannot be borrowed as mutable
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/did_you_mean/issue-40823.stderr b/src/test/ui/did_you_mean/issue-40823.stderr
index 73473406a9a..67703a1497f 100644
--- a/src/test/ui/did_you_mean/issue-40823.stderr
+++ b/src/test/ui/did_you_mean/issue-40823.stderr
@@ -4,7 +4,7 @@ error[E0596]: cannot borrow `*buf` as mutable, as it is behind a `&` reference
 LL |     let mut buf = &[1, 2, 3, 4];
    |                   ------------- help: consider changing this to be a mutable reference: `&mut [1, 2, 3, 4]`
 LL |     buf.iter_mut();
-   |     ^^^ `buf` is a `&` reference, so the data it refers to cannot be borrowed as mutable
+   |     ^^^^^^^^^^^^^^ `buf` is a `&` reference, so the data it refers to cannot be borrowed as mutable
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/did_you_mean/recursion_limit.stderr b/src/test/ui/did_you_mean/recursion_limit.stderr
index fa8bee184a7..247fe4b5b07 100644
--- a/src/test/ui/did_you_mean/recursion_limit.stderr
+++ b/src/test/ui/did_you_mean/recursion_limit.stderr
@@ -4,7 +4,7 @@ error[E0275]: overflow evaluating the requirement `K: Send`
 LL |     is_send::<A>();
    |     ^^^^^^^^^^^^
    |
-   = help: consider adding a `#![recursion_limit="20"]` attribute to your crate (`recursion_limit`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "20"]` attribute to your crate (`recursion_limit`)
 note: required because it appears within the type `J`
   --> $DIR/recursion_limit.rs:24:9
    |
diff --git a/src/test/ui/did_you_mean/recursion_limit_deref.stderr b/src/test/ui/did_you_mean/recursion_limit_deref.stderr
index 8339cc291cf..658207a47c9 100644
--- a/src/test/ui/did_you_mean/recursion_limit_deref.stderr
+++ b/src/test/ui/did_you_mean/recursion_limit_deref.stderr
@@ -4,7 +4,7 @@ error[E0055]: reached the recursion limit while auto-dereferencing `J`
 LL |     let x: &Bottom = &t;
    |                      ^^ deref recursion limit reached
    |
-   = help: consider adding a `#![recursion_limit="20"]` attribute to your crate (`recursion_limit_deref`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "20"]` attribute to your crate (`recursion_limit_deref`)
 
 error[E0308]: mismatched types
   --> $DIR/recursion_limit_deref.rs:50:22
diff --git a/src/test/ui/did_you_mean/recursion_limit_macro.stderr b/src/test/ui/did_you_mean/recursion_limit_macro.stderr
index 0c6fdebd509..609488e4f2f 100644
--- a/src/test/ui/did_you_mean/recursion_limit_macro.stderr
+++ b/src/test/ui/did_you_mean/recursion_limit_macro.stderr
@@ -7,7 +7,7 @@ LL |     ($t:tt $($tail:tt)*) => { recurse!($($tail)*) };
 LL |     recurse!(0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9);
    |     -------------------------------------------------- in this macro invocation
    |
-   = help: consider adding a `#![recursion_limit="20"]` attribute to your crate (`recursion_limit_macro`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "20"]` attribute to your crate (`recursion_limit_macro`)
    = note: this error originates in the macro `recurse` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to previous error
diff --git a/src/test/ui/dropck/drop-with-active-borrows-1.stderr b/src/test/ui/dropck/drop-with-active-borrows-1.stderr
index 7fed27adaff..8d6a7f3721f 100644
--- a/src/test/ui/dropck/drop-with-active-borrows-1.stderr
+++ b/src/test/ui/dropck/drop-with-active-borrows-1.stderr
@@ -2,7 +2,7 @@ error[E0505]: cannot move out of `a` because it is borrowed
   --> $DIR/drop-with-active-borrows-1.rs:4:10
    |
 LL |     let b: Vec<&str> = a.lines().collect();
-   |                        - borrow of `a` occurs here
+   |                        --------- borrow of `a` occurs here
 LL |     drop(a);
    |          ^ move out of `a` occurs here
 LL |     for s in &b {
diff --git a/src/test/ui/dropck/drop-with-active-borrows-2.stderr b/src/test/ui/dropck/drop-with-active-borrows-2.stderr
index ffec9306b77..24650dfac02 100644
--- a/src/test/ui/dropck/drop-with-active-borrows-2.stderr
+++ b/src/test/ui/dropck/drop-with-active-borrows-2.stderr
@@ -2,7 +2,7 @@ error[E0515]: cannot return value referencing local variable `raw_lines`
   --> $DIR/drop-with-active-borrows-2.rs:3:5
    |
 LL |     raw_lines.iter().map(|l| l.trim()).collect()
-   |     ---------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |     ----------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |     |
    |     returns a value referencing data owned by the current function
    |     `raw_lines` is borrowed here
diff --git a/src/test/ui/error-codes/E0034.stderr b/src/test/ui/error-codes/E0034.stderr
index 83718a1e273..e2962170265 100644
--- a/src/test/ui/error-codes/E0034.stderr
+++ b/src/test/ui/error-codes/E0034.stderr
@@ -16,12 +16,12 @@ LL |     fn foo() {}
    |     ^^^^^^^^
 help: disambiguate the associated function for candidate #1
    |
-LL |     Trait1::foo()
-   |     ~~~~~~~~
+LL |     <Test as Trait1>::foo()
+   |     ~~~~~~~~~~~~~~~~~~
 help: disambiguate the associated function for candidate #2
    |
-LL |     Trait2::foo()
-   |     ~~~~~~~~
+LL |     <Test as Trait2>::foo()
+   |     ~~~~~~~~~~~~~~~~~~
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/error-codes/E0055.stderr b/src/test/ui/error-codes/E0055.stderr
index 1b8c5760e65..a52c9096235 100644
--- a/src/test/ui/error-codes/E0055.stderr
+++ b/src/test/ui/error-codes/E0055.stderr
@@ -4,7 +4,7 @@ error[E0055]: reached the recursion limit while auto-dereferencing `Foo`
 LL |     ref_foo.foo();
    |             ^^^ deref recursion limit reached
    |
-   = help: consider adding a `#![recursion_limit="8"]` attribute to your crate (`E0055`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "8"]` attribute to your crate (`E0055`)
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/error-codes/E0161.edition.stderr b/src/test/ui/error-codes/E0161.edition.stderr
index 6beb29c57d5..1060675cd45 100644
--- a/src/test/ui/error-codes/E0161.edition.stderr
+++ b/src/test/ui/error-codes/E0161.edition.stderr
@@ -2,7 +2,7 @@ error[E0161]: cannot move a value of type dyn Bar: the size of dyn Bar cannot be
   --> $DIR/E0161.rs:29:5
    |
 LL |     x.f();
-   |     ^
+   |     ^^^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/error-codes/E0161.migrate.stderr b/src/test/ui/error-codes/E0161.migrate.stderr
index 6beb29c57d5..1060675cd45 100644
--- a/src/test/ui/error-codes/E0161.migrate.stderr
+++ b/src/test/ui/error-codes/E0161.migrate.stderr
@@ -2,7 +2,7 @@ error[E0161]: cannot move a value of type dyn Bar: the size of dyn Bar cannot be
   --> $DIR/E0161.rs:29:5
    |
 LL |     x.f();
-   |     ^
+   |     ^^^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/error-codes/E0161.nll.stderr b/src/test/ui/error-codes/E0161.nll.stderr
index 6beb29c57d5..1060675cd45 100644
--- a/src/test/ui/error-codes/E0161.nll.stderr
+++ b/src/test/ui/error-codes/E0161.nll.stderr
@@ -2,7 +2,7 @@ error[E0161]: cannot move a value of type dyn Bar: the size of dyn Bar cannot be
   --> $DIR/E0161.rs:29:5
    |
 LL |     x.f();
-   |     ^
+   |     ^^^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/error-codes/E0161.zflags.stderr b/src/test/ui/error-codes/E0161.zflags.stderr
index 6beb29c57d5..1060675cd45 100644
--- a/src/test/ui/error-codes/E0161.zflags.stderr
+++ b/src/test/ui/error-codes/E0161.zflags.stderr
@@ -2,7 +2,7 @@ error[E0161]: cannot move a value of type dyn Bar: the size of dyn Bar cannot be
   --> $DIR/E0161.rs:29:5
    |
 LL |     x.f();
-   |     ^
+   |     ^^^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/error-codes/E0275.stderr b/src/test/ui/error-codes/E0275.stderr
index 15d851aa934..e13f0961a18 100644
--- a/src/test/ui/error-codes/E0275.stderr
+++ b/src/test/ui/error-codes/E0275.stderr
@@ -4,7 +4,7 @@ error[E0275]: overflow evaluating the requirement `Bar<Bar<Bar<Bar<Bar<Bar<Bar<B
 LL | impl<T> Foo for T where Bar<T>: Foo {}
    |                                 ^^^
    |
-   = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`E0275`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`E0275`)
 note: required because of the requirements on the impl of `Foo` for `Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<T>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>`
   --> $DIR/E0275.rs:5:9
    |
diff --git a/src/test/ui/error-codes/E0407.stderr b/src/test/ui/error-codes/E0407.stderr
index 567fc879040..6f6d1ff6a8f 100644
--- a/src/test/ui/error-codes/E0407.stderr
+++ b/src/test/ui/error-codes/E0407.stderr
@@ -2,7 +2,10 @@ error[E0407]: method `b` is not a member of trait `Foo`
   --> $DIR/E0407.rs:9:5
    |
 LL |     fn b() {}
-   |     ^^^^^^^^^ not a member of trait `Foo`
+   |     ^^^-^^^^^
+   |     |  |
+   |     |  help: there is an associated function with a similar name: `a`
+   |     not a member of trait `Foo`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/error-codes/E0499.stderr b/src/test/ui/error-codes/E0499.stderr
index d56baf72272..af5a1e18633 100644
--- a/src/test/ui/error-codes/E0499.stderr
+++ b/src/test/ui/error-codes/E0499.stderr
@@ -7,7 +7,7 @@ LL |     let mut a = &mut i;
    |                 ^^^^^^ second mutable borrow occurs here
 LL |     a.use_mut();
 LL |     x.use_mut();
-   |     - first borrow later used here
+   |     ----------- first borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/error-codes/E0502.nll.stderr b/src/test/ui/error-codes/E0502.nll.stderr
index e5671ee49e6..a3c7ef76189 100644
--- a/src/test/ui/error-codes/E0502.nll.stderr
+++ b/src/test/ui/error-codes/E0502.nll.stderr
@@ -6,7 +6,7 @@ LL |     let ref y = a;
 LL |     bar(a);
    |         ^ mutable borrow occurs here
 LL |     y.use_ref();
-   |     - immutable borrow later used here
+   |     ----------- immutable borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/error-codes/E0502.stderr b/src/test/ui/error-codes/E0502.stderr
index cade6d71852..94cc89754db 100644
--- a/src/test/ui/error-codes/E0502.stderr
+++ b/src/test/ui/error-codes/E0502.stderr
@@ -6,7 +6,7 @@ LL |     let ref y = a;
 LL |     bar(a);
    |     ^^^^^^ mutable borrow occurs here
 LL |     y.use_ref();
-   |     - immutable borrow later used here
+   |     ----------- immutable borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/error-codes/E0503.stderr b/src/test/ui/error-codes/E0503.stderr
index 106dda2bc22..fafe363eb47 100644
--- a/src/test/ui/error-codes/E0503.stderr
+++ b/src/test/ui/error-codes/E0503.stderr
@@ -6,7 +6,7 @@ LL |     let _borrow = &mut value;
 LL |     let _sum = value + 1;
    |                ^^^^^ use of borrowed `value`
 LL |     _borrow.use_mut();
-   |     ------- borrow later used here
+   |     ----------------- borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/error-codes/E0505.stderr b/src/test/ui/error-codes/E0505.stderr
index 4d9d1ef121c..bd3f37f54e0 100644
--- a/src/test/ui/error-codes/E0505.stderr
+++ b/src/test/ui/error-codes/E0505.stderr
@@ -6,7 +6,7 @@ LL |         let _ref_to_val: &Value = &x;
 LL |         eat(x);
    |             ^ move out of `x` occurs here
 LL |         _ref_to_val.use_ref();
-   |         ----------- borrow later used here
+   |         --------------------- borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/error-codes/E0507.stderr b/src/test/ui/error-codes/E0507.stderr
index cd5e467944b..3837e206169 100644
--- a/src/test/ui/error-codes/E0507.stderr
+++ b/src/test/ui/error-codes/E0507.stderr
@@ -2,7 +2,7 @@ error[E0507]: cannot move out of dereference of `Ref<'_, TheDarkKnight>`
   --> $DIR/E0507.rs:12:5
    |
 LL |     x.borrow().nothing_is_true();
-   |     ^^^^^^^^^^ move occurs because value has type `TheDarkKnight`, which does not implement the `Copy` trait
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ move occurs because value has type `TheDarkKnight`, which does not implement the `Copy` trait
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/generator/dropck-resume.stderr b/src/test/ui/generator/dropck-resume.stderr
index ecf92e7e3ae..b0756eb5589 100644
--- a/src/test/ui/generator/dropck-resume.stderr
+++ b/src/test/ui/generator/dropck-resume.stderr
@@ -5,7 +5,7 @@ LL |     let z = &mut y;
    |             ------ mutable borrow occurs here
 ...
 LL |         r = y.as_ref().unwrap();
-   |             ^ immutable borrow occurs here
+   |             ^^^^^^^^^^ immutable borrow occurs here
 LL |
 LL |     }
    |     - mutable borrow might be used here, when `g` is dropped and runs the destructor for generator
diff --git a/src/test/ui/generator/dropck.stderr b/src/test/ui/generator/dropck.stderr
index 8bb860f288f..7bb188352d7 100644
--- a/src/test/ui/generator/dropck.stderr
+++ b/src/test/ui/generator/dropck.stderr
@@ -2,7 +2,7 @@ error[E0597]: `*cell` does not live long enough
   --> $DIR/dropck.rs:10:40
    |
 LL |     let ref_ = Box::leak(Box::new(Some(cell.borrow_mut())));
-   |                                        ^^^^ borrowed value does not live long enough
+   |                                        ^^^^^^^^^^^^^^^^^ borrowed value does not live long enough
 ...
 LL | }
    | -
diff --git a/src/test/ui/generator/yield-in-box.rs b/src/test/ui/generator/yield-in-box.rs
index 65f368df9cb..dd6fa7c151a 100644
--- a/src/test/ui/generator/yield-in-box.rs
+++ b/src/test/ui/generator/yield-in-box.rs
@@ -1,8 +1,10 @@
 // run-pass
-
 // Test that box-statements with yields in them work.
 
-#![feature(generators, box_syntax)]
+#![feature(generators, box_syntax, generator_trait)]
+use std::pin::Pin;
+use std::ops::Generator;
+use std::ops::GeneratorState;
 
 fn main() {
     let x = 0i32;
@@ -15,4 +17,8 @@ fn main() {
             _t => {}
         }
     };
+
+    let mut g = |_| box yield;
+    assert_eq!(Pin::new(&mut g).resume(1), GeneratorState::Yielded(()));
+    assert_eq!(Pin::new(&mut g).resume(2), GeneratorState::Complete(box 2));
 }
diff --git a/src/test/ui/generator/yield-in-box.stderr b/src/test/ui/generator/yield-in-box.stderr
index 24de18edb0f..7602e803945 100644
--- a/src/test/ui/generator/yield-in-box.stderr
+++ b/src/test/ui/generator/yield-in-box.stderr
@@ -1,5 +1,5 @@
 warning: unused generator that must be used
-  --> $DIR/yield-in-box.rs:9:5
+  --> $DIR/yield-in-box.rs:11:5
    |
 LL | /     || {
 LL | |         let y = 2u32;
diff --git a/src/test/ui/hashmap/hashmap-iter-value-lifetime.nll.stderr b/src/test/ui/hashmap/hashmap-iter-value-lifetime.nll.stderr
deleted file mode 100644
index 312a91adca6..00000000000
--- a/src/test/ui/hashmap/hashmap-iter-value-lifetime.nll.stderr
+++ /dev/null
@@ -1,15 +0,0 @@
-error[E0502]: cannot borrow `my_stuff` as mutable because it is also borrowed as immutable
-  --> $DIR/hashmap-iter-value-lifetime.rs:7:5
-   |
-LL |     let (_, thing) = my_stuff.iter().next().unwrap();
-   |                      -------- immutable borrow occurs here
-LL | 
-LL |     my_stuff.clear();
-   |     ^^^^^^^^ mutable borrow occurs here
-LL | 
-LL |     println!("{}", *thing);
-   |                    ------ immutable borrow later used here
-
-error: aborting due to previous error
-
-For more information about this error, try `rustc --explain E0502`.
diff --git a/src/test/ui/hashmap/hashmap-iter-value-lifetime.stderr b/src/test/ui/hashmap/hashmap-iter-value-lifetime.stderr
index f7626b13bad..0724fec9055 100644
--- a/src/test/ui/hashmap/hashmap-iter-value-lifetime.stderr
+++ b/src/test/ui/hashmap/hashmap-iter-value-lifetime.stderr
@@ -2,7 +2,7 @@ error[E0502]: cannot borrow `my_stuff` as mutable because it is also borrowed as
   --> $DIR/hashmap-iter-value-lifetime.rs:7:5
    |
 LL |     let (_, thing) = my_stuff.iter().next().unwrap();
-   |                      -------- immutable borrow occurs here
+   |                      --------------- immutable borrow occurs here
 LL | 
 LL |     my_stuff.clear();
    |     ^^^^^^^^^^^^^^^^ mutable borrow occurs here
diff --git a/src/test/ui/hashmap/hashmap-lifetimes.nll.stderr b/src/test/ui/hashmap/hashmap-lifetimes.nll.stderr
deleted file mode 100644
index aa8e890c168..00000000000
--- a/src/test/ui/hashmap/hashmap-lifetimes.nll.stderr
+++ /dev/null
@@ -1,13 +0,0 @@
-error[E0502]: cannot borrow `my_stuff` as mutable because it is also borrowed as immutable
-  --> $DIR/hashmap-lifetimes.rs:6:5
-   |
-LL |     let mut it = my_stuff.iter();
-   |                  -------- immutable borrow occurs here
-LL |     my_stuff.insert(1, 43);
-   |     ^^^^^^^^ mutable borrow occurs here
-LL |     it;
-   |     -- immutable borrow later used here
-
-error: aborting due to previous error
-
-For more information about this error, try `rustc --explain E0502`.
diff --git a/src/test/ui/hashmap/hashmap-lifetimes.stderr b/src/test/ui/hashmap/hashmap-lifetimes.stderr
index 497c7d1216c..d1bcd53ae3b 100644
--- a/src/test/ui/hashmap/hashmap-lifetimes.stderr
+++ b/src/test/ui/hashmap/hashmap-lifetimes.stderr
@@ -2,7 +2,7 @@ error[E0502]: cannot borrow `my_stuff` as mutable because it is also borrowed as
   --> $DIR/hashmap-lifetimes.rs:6:5
    |
 LL |     let mut it = my_stuff.iter();
-   |                  -------- immutable borrow occurs here
+   |                  --------------- immutable borrow occurs here
 LL |     my_stuff.insert(1, 43);
    |     ^^^^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
 LL |     it;
diff --git a/src/test/ui/hr-subtype/hr-subtype.bound_a_b_ret_a_vs_bound_a_ret_a.nll.stderr b/src/test/ui/hr-subtype/hr-subtype.bound_a_b_ret_a_vs_bound_a_ret_a.nll.stderr
index 439a113ef38..87d826021b7 100644
--- a/src/test/ui/hr-subtype/hr-subtype.bound_a_b_ret_a_vs_bound_a_ret_a.nll.stderr
+++ b/src/test/ui/hr-subtype/hr-subtype.bound_a_b_ret_a_vs_bound_a_ret_a.nll.stderr
@@ -8,8 +8,8 @@ LL | / check! { bound_a_b_ret_a_vs_bound_a_ret_a: (for<'a,'b> fn(&'a u32, &'b u3
 LL | | for<'a>    fn(&'a u32, &'a u32) -> &'a u32) }
    | |_____________________________________________- in this macro invocation
    |
-   = note: expected enum `Option<for<'r, 's> fn(&'r u32, &'s u32) -> &'r u32>`
-              found enum `Option<for<'r> fn(&'r u32, &'r u32) -> &'r u32>`
+   = note: expected enum `Option<for<'a, 'b> fn(&'a u32, &'b u32) -> &'a u32>`
+              found enum `Option<for<'a> fn(&'a u32, &'a u32) -> &'a u32>`
    = note: this error originates in the macro `check` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to previous error
diff --git a/src/test/ui/hr-subtype/hr-subtype.bound_a_vs_free_x.nll.stderr b/src/test/ui/hr-subtype/hr-subtype.bound_a_vs_free_x.nll.stderr
index 61b3f0ca284..bd97f6f0906 100644
--- a/src/test/ui/hr-subtype/hr-subtype.bound_a_vs_free_x.nll.stderr
+++ b/src/test/ui/hr-subtype/hr-subtype.bound_a_vs_free_x.nll.stderr
@@ -8,7 +8,7 @@ LL | / check! { bound_a_vs_free_x: (for<'a> fn(&'a u32),
 LL | | fn(&'x u32)) }
    | |______________- in this macro invocation
    |
-   = note: expected enum `Option<for<'r> fn(&'r u32)>`
+   = note: expected enum `Option<for<'a> fn(&'a u32)>`
               found enum `Option<fn(&u32)>`
    = note: this error originates in the macro `check` (in Nightly builds, run with -Z macro-backtrace for more info)
 
diff --git a/src/test/ui/hr-subtype/hr-subtype.bound_inv_a_b_vs_bound_inv_a.nll.stderr b/src/test/ui/hr-subtype/hr-subtype.bound_inv_a_b_vs_bound_inv_a.nll.stderr
index 75e2ba58f33..874909bf486 100644
--- a/src/test/ui/hr-subtype/hr-subtype.bound_inv_a_b_vs_bound_inv_a.nll.stderr
+++ b/src/test/ui/hr-subtype/hr-subtype.bound_inv_a_b_vs_bound_inv_a.nll.stderr
@@ -8,8 +8,8 @@ LL | / check! { bound_inv_a_b_vs_bound_inv_a: (for<'a,'b> fn(Inv<'a>, Inv<'b>),
 LL | | for<'a>    fn(Inv<'a>, Inv<'a>)) }
    | |__________________________________- in this macro invocation
    |
-   = note: expected enum `Option<for<'r, 's> fn(Inv<'r>, Inv<'s>)>`
-              found enum `Option<for<'r> fn(Inv<'r>, Inv<'r>)>`
+   = note: expected enum `Option<for<'a, 'b> fn(Inv<'a>, Inv<'b>)>`
+              found enum `Option<for<'a> fn(Inv<'a>, Inv<'a>)>`
    = note: this error originates in the macro `check` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0308]: mismatched types
@@ -22,8 +22,8 @@ LL | / check! { bound_inv_a_b_vs_bound_inv_a: (for<'a,'b> fn(Inv<'a>, Inv<'b>),
 LL | | for<'a>    fn(Inv<'a>, Inv<'a>)) }
    | |__________________________________- in this macro invocation
    |
-   = note: expected enum `Option<for<'r, 's> fn(Inv<'r>, Inv<'s>)>`
-              found enum `Option<for<'r> fn(Inv<'r>, Inv<'r>)>`
+   = note: expected enum `Option<for<'a, 'b> fn(Inv<'a>, Inv<'b>)>`
+              found enum `Option<for<'a> fn(Inv<'a>, Inv<'a>)>`
    = note: this error originates in the macro `check` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 2 previous errors
diff --git a/src/test/ui/hrtb/hrtb-debruijn-in-receiver.stderr b/src/test/ui/hrtb/hrtb-debruijn-in-receiver.stderr
index 70d5b3c2ec5..fa391ecba8a 100644
--- a/src/test/ui/hrtb/hrtb-debruijn-in-receiver.stderr
+++ b/src/test/ui/hrtb/hrtb-debruijn-in-receiver.stderr
@@ -2,9 +2,9 @@ error[E0499]: cannot borrow `foo` as mutable more than once at a time
   --> $DIR/hrtb-debruijn-in-receiver.rs:17:5
    |
 LL |     foo.insert();
-   |     --- first mutable borrow occurs here
+   |     ------------ first mutable borrow occurs here
 LL |     foo.insert();
-   |     ^^^
+   |     ^^^^^^^^^^^^
    |     |
    |     second mutable borrow occurs here
    |     first borrow later used here
diff --git a/src/test/ui/hygiene/assoc_item_ctxt.stderr b/src/test/ui/hygiene/assoc_item_ctxt.stderr
index 6e4fecf0ce4..517b1ff5988 100644
--- a/src/test/ui/hygiene/assoc_item_ctxt.stderr
+++ b/src/test/ui/hygiene/assoc_item_ctxt.stderr
@@ -2,7 +2,10 @@ error[E0407]: method `method` is not a member of trait `Tr`
   --> $DIR/assoc_item_ctxt.rs:35:13
    |
 LL |             fn method() {}
-   |             ^^^^^^^^^^^^^^ not a member of trait `Tr`
+   |             ^^^------^^^^^
+   |             |  |
+   |             |  help: there is an associated function with a similar name: `method`
+   |             not a member of trait `Tr`
 ...
 LL |     mac_trait_impl!();
    |     ------------------ in this macro invocation
diff --git a/src/test/ui/hygiene/fields-numeric-borrowck.stderr b/src/test/ui/hygiene/fields-numeric-borrowck.stderr
index fb90825c0d9..bc13aa62f4d 100644
--- a/src/test/ui/hygiene/fields-numeric-borrowck.stderr
+++ b/src/test/ui/hygiene/fields-numeric-borrowck.stderr
@@ -7,7 +7,7 @@ LL |     let S { 0: ref mut borrow2 } = s;
    |                ^^^^^^^^^^^^^^^ second mutable borrow occurs here
 ...
 LL |     borrow1.use_mut();
-   |     ------- first borrow later used here
+   |     ----------------- first borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/hygiene/globs.stderr b/src/test/ui/hygiene/globs.stderr
index c2497f8ff74..6c8b707b8e2 100644
--- a/src/test/ui/hygiene/globs.stderr
+++ b/src/test/ui/hygiene/globs.stderr
@@ -4,7 +4,7 @@ error[E0425]: cannot find function `f` in this scope
 LL |         f();
    |         ^ not found in this scope
    |
-help: consider importing one of these items
+help: consider importing this function
    |
 LL | use foo::f;
    |
@@ -37,7 +37,7 @@ LL | n!(f);
 LL |         n!(f);
    |            ^ not found in this scope
    |
-   = note: consider importing one of these items:
+   = note: consider importing this function:
            foo::f
    = note: this error originates in the macro `n` (in Nightly builds, run with -Z macro-backtrace for more info)
 
@@ -50,7 +50,7 @@ LL | n!(f);
 LL |                 f
    |                 ^ not found in this scope
    |
-   = note: consider importing one of these items:
+   = note: consider importing this function:
            foo::f
    = note: this error originates in the macro `n` (in Nightly builds, run with -Z macro-backtrace for more info)
 
diff --git a/src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-unrelated.nll.stderr b/src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-unrelated.nll.stderr
index 8cf89f164b1..0fe9b06355f 100644
--- a/src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-unrelated.nll.stderr
+++ b/src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-unrelated.nll.stderr
@@ -4,7 +4,11 @@ error[E0700]: hidden type for `impl Trait` captures lifetime that does not appea
 LL | fn upper_bounds<'a, 'b, 'c, 'd, 'e>(a: Ordinary<'a>, b: Ordinary<'b>) -> impl Trait<'d, 'e>
    |                                                                          ^^^^^^^^^^^^^^^^^^
    |
-   = note: hidden type `Ordinary<'_>` captures lifetime '_#9r
+note: hidden type `Ordinary<'b>` captures the lifetime `'b` as defined on the function body at 16:21
+  --> $DIR/ordinary-bounds-unrelated.rs:16:21
+   |
+LL | fn upper_bounds<'a, 'b, 'c, 'd, 'e>(a: Ordinary<'a>, b: Ordinary<'b>) -> impl Trait<'d, 'e>
+   |                     ^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-unsuited.nll.stderr b/src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-unsuited.nll.stderr
index 1bcb28120ed..6de77523db5 100644
--- a/src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-unsuited.nll.stderr
+++ b/src/test/ui/impl-trait/multiple-lifetimes/ordinary-bounds-unsuited.nll.stderr
@@ -4,7 +4,11 @@ error[E0700]: hidden type for `impl Trait` captures lifetime that does not appea
 LL | fn upper_bounds<'a, 'b>(a: Ordinary<'a>, b: Ordinary<'b>) -> impl Trait<'a, 'b>
    |                                                              ^^^^^^^^^^^^^^^^^^
    |
-   = note: hidden type `Ordinary<'_>` captures lifetime '_#6r
+note: hidden type `Ordinary<'b>` captures the lifetime `'b` as defined on the function body at 18:21
+  --> $DIR/ordinary-bounds-unsuited.rs:18:21
+   |
+LL | fn upper_bounds<'a, 'b>(a: Ordinary<'a>, b: Ordinary<'b>) -> impl Trait<'a, 'b>
+   |                     ^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/imports/glob-resolve1.stderr b/src/test/ui/imports/glob-resolve1.stderr
index 2c7a8ad5c1a..3b66a5e3150 100644
--- a/src/test/ui/imports/glob-resolve1.stderr
+++ b/src/test/ui/imports/glob-resolve1.stderr
@@ -4,10 +4,11 @@ error[E0425]: cannot find function `fpriv` in this scope
 LL |     fpriv();
    |     ^^^^^ not found in this scope
    |
-help: consider importing this function
-   |
-LL | use bar::fpriv;
+note: function `bar::fpriv` exists but is inaccessible
+  --> $DIR/glob-resolve1.rs:7:5
    |
+LL |     fn fpriv() {}
+   |     ^^^^^^^^^^ not accessible
 
 error[E0425]: cannot find function `epriv` in this scope
   --> $DIR/glob-resolve1.rs:27:5
@@ -15,10 +16,11 @@ error[E0425]: cannot find function `epriv` in this scope
 LL |     epriv();
    |     ^^^^^ not found in this scope
    |
-help: consider importing this function
-   |
-LL | use bar::epriv;
+note: function `bar::epriv` exists but is inaccessible
+  --> $DIR/glob-resolve1.rs:9:9
    |
+LL |         fn epriv();
+   |         ^^^^^^^^^^^ not accessible
 
 error[E0423]: expected value, found enum `B`
   --> $DIR/glob-resolve1.rs:28:5
@@ -44,10 +46,11 @@ error[E0425]: cannot find value `C` in this scope
 LL |     C;
    |     ^ not found in this scope
    |
-help: consider importing this unit struct
-   |
-LL | use bar::C;
+note: unit struct `bar::C` exists but is inaccessible
+  --> $DIR/glob-resolve1.rs:18:5
    |
+LL |     struct C;
+   |     ^^^^^^^^^ not accessible
 
 error[E0425]: cannot find function `import` in this scope
   --> $DIR/glob-resolve1.rs:30:5
@@ -67,16 +70,13 @@ LL |     pub enum B {
    |     ---------- similarly named enum `B` defined here
 ...
 LL |     foo::<A>();
-   |           ^
-   |
-help: an enum with a similar name exists
+   |           ^ help: an enum with a similar name exists: `B`
    |
-LL |     foo::<B>();
-   |           ~
-help: consider importing this enum
-   |
-LL | use bar::A;
+note: enum `bar::A` exists but is inaccessible
+  --> $DIR/glob-resolve1.rs:11:5
    |
+LL |     enum A {
+   |     ^^^^^^ not accessible
 
 error[E0412]: cannot find type `C` in this scope
   --> $DIR/glob-resolve1.rs:33:11
@@ -85,16 +85,13 @@ LL |     pub enum B {
    |     ---------- similarly named enum `B` defined here
 ...
 LL |     foo::<C>();
-   |           ^
-   |
-help: an enum with a similar name exists
-   |
-LL |     foo::<B>();
-   |           ~
-help: consider importing this struct
+   |           ^ help: an enum with a similar name exists: `B`
    |
-LL | use bar::C;
+note: struct `bar::C` exists but is inaccessible
+  --> $DIR/glob-resolve1.rs:18:5
    |
+LL |     struct C;
+   |     ^^^^^^^^^ not accessible
 
 error[E0412]: cannot find type `D` in this scope
   --> $DIR/glob-resolve1.rs:34:11
@@ -103,16 +100,13 @@ LL |     pub enum B {
    |     ---------- similarly named enum `B` defined here
 ...
 LL |     foo::<D>();
-   |           ^
-   |
-help: an enum with a similar name exists
-   |
-LL |     foo::<B>();
-   |           ~
-help: consider importing this type alias
+   |           ^ help: an enum with a similar name exists: `B`
    |
-LL | use bar::D;
+note: type alias `bar::D` exists but is inaccessible
+  --> $DIR/glob-resolve1.rs:20:5
    |
+LL |     type D = isize;
+   |     ^^^^^^^^^^^^^^^ not accessible
 
 error: aborting due to 8 previous errors
 
diff --git a/src/test/ui/imports/issue-4366-2.stderr b/src/test/ui/imports/issue-4366-2.stderr
index a86ec7fabea..4c94634ee60 100644
--- a/src/test/ui/imports/issue-4366-2.stderr
+++ b/src/test/ui/imports/issue-4366-2.stderr
@@ -4,10 +4,11 @@ error[E0412]: cannot find type `Bar` in this scope
 LL |         fn sub() -> Bar { 1 }
    |                     ^^^ not found in this scope
    |
-help: consider importing this type alias
-   |
-LL |         use a::b::Bar;
+note: type alias `a::b::Bar` exists but is inaccessible
+  --> $DIR/issue-4366-2.rs:11:9
    |
+LL |         type Bar = isize;
+   |         ^^^^^^^^^^^^^^^^^ not accessible
 
 error[E0423]: expected function, found module `foo`
   --> $DIR/issue-4366-2.rs:25:5
diff --git a/src/test/ui/infinite/infinite-autoderef.stderr b/src/test/ui/infinite/infinite-autoderef.stderr
index 1f26ba30000..03e4718f5df 100644
--- a/src/test/ui/infinite/infinite-autoderef.stderr
+++ b/src/test/ui/infinite/infinite-autoderef.stderr
@@ -12,7 +12,7 @@ error[E0055]: reached the recursion limit while auto-dereferencing `Foo`
 LL |     Foo.foo;
    |     ^^^^^^^ deref recursion limit reached
    |
-   = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`infinite_autoderef`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`infinite_autoderef`)
 
 error[E0055]: reached the recursion limit while auto-dereferencing `Foo`
   --> $DIR/infinite-autoderef.rs:25:9
@@ -20,7 +20,7 @@ error[E0055]: reached the recursion limit while auto-dereferencing `Foo`
 LL |     Foo.foo;
    |         ^^^ deref recursion limit reached
    |
-   = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`infinite_autoderef`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`infinite_autoderef`)
 
 error[E0609]: no field `foo` on type `Foo`
   --> $DIR/infinite-autoderef.rs:25:9
@@ -34,7 +34,7 @@ error[E0055]: reached the recursion limit while auto-dereferencing `Foo`
 LL |     Foo.bar();
    |         ^^^ deref recursion limit reached
    |
-   = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`infinite_autoderef`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`infinite_autoderef`)
 
 error[E0599]: no method named `bar` found for struct `Foo` in the current scope
   --> $DIR/infinite-autoderef.rs:26:9
diff --git a/src/test/ui/infinite/infinite-macro-expansion.stderr b/src/test/ui/infinite/infinite-macro-expansion.stderr
index c7d9118d3f3..15654dfaf88 100644
--- a/src/test/ui/infinite/infinite-macro-expansion.stderr
+++ b/src/test/ui/infinite/infinite-macro-expansion.stderr
@@ -7,7 +7,7 @@ LL |     () => (recursive!())
 LL |     recursive!()
    |     ------------ in this macro invocation
    |
-   = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`infinite_macro_expansion`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`infinite_macro_expansion`)
    = note: this error originates in the macro `recursive` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to previous error
diff --git a/src/test/ui/issues/issue-13497-2.stderr b/src/test/ui/issues/issue-13497-2.stderr
index 8ad921027e2..6f72b79f2a5 100644
--- a/src/test/ui/issues/issue-13497-2.stderr
+++ b/src/test/ui/issues/issue-13497-2.stderr
@@ -1,13 +1,14 @@
 error[E0515]: cannot return value referencing local variable `rawLines`
   --> $DIR/issue-13497-2.rs:3:5
    |
-LL |       rawLines
-   |       ^-------
-   |       |
-   |  _____`rawLines` is borrowed here
-   | |
-LL | |         .iter().map(|l| l.trim()).collect()
-   | |___________________________________________^ returns a value referencing data owned by the current function
+LL |        rawLines
+   |   _____^
+   |  |_____|
+   | ||
+LL | ||         .iter().map(|l| l.trim()).collect()
+   | ||_______________-___________________________^ returns a value referencing data owned by the current function
+   | |________________|
+   |                  `rawLines` is borrowed here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-16098.stderr b/src/test/ui/issues/issue-16098.stderr
index a63bcd9ba5c..64280219d75 100644
--- a/src/test/ui/issues/issue-16098.stderr
+++ b/src/test/ui/issues/issue-16098.stderr
@@ -7,7 +7,7 @@ LL |             $n + prob1!($n - 1);
 LL |     println!("Problem 1: {}", prob1!(1000));
    |                               ------------ in this macro invocation
    |
-   = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`issue_16098`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_16098`)
    = note: this error originates in the macro `prob1` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to previous error
diff --git a/src/test/ui/issues/issue-18400.stderr b/src/test/ui/issues/issue-18400.stderr
index 92d53088442..92e0f60079f 100644
--- a/src/test/ui/issues/issue-18400.stderr
+++ b/src/test/ui/issues/issue-18400.stderr
@@ -4,7 +4,7 @@ error[E0275]: overflow evaluating the requirement `_: Sized`
 LL |     0.contains(bits);
    |       ^^^^^^^^
    |
-   = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`issue_18400`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_18400`)
 note: required because of the requirements on the impl of `Set<&[_]>` for `{integer}`
   --> $DIR/issue-18400.rs:6:16
    |
diff --git a/src/test/ui/issues/issue-19163.stderr b/src/test/ui/issues/issue-19163.stderr
index af509aa59d4..def032ba1bb 100644
--- a/src/test/ui/issues/issue-19163.stderr
+++ b/src/test/ui/issues/issue-19163.stderr
@@ -1,8 +1,10 @@
 error[E0596]: cannot borrow data in a `&` reference as mutable
-  --> $DIR/issue-19163.rs:9:14
+  --> $DIR/issue-19163.rs:9:5
    |
 LL |     mywrite!(&v, "Hello world");
-   |              ^^ cannot borrow as mutable
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot borrow as mutable
+   |
+   = note: this error originates in the macro `mywrite` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-20413.stderr b/src/test/ui/issues/issue-20413.stderr
index 572c8ee33ce..9135c5ac36a 100644
--- a/src/test/ui/issues/issue-20413.stderr
+++ b/src/test/ui/issues/issue-20413.stderr
@@ -13,7 +13,7 @@ error[E0275]: overflow evaluating the requirement `NoData<NoData<NoData<NoData<N
 LL | impl<T> Foo for T where NoData<T>: Foo {
    |                                    ^^^
    |
-   = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`issue_20413`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_20413`)
 note: required because of the requirements on the impl of `Foo` for `NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<T>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>`
   --> $DIR/issue-20413.rs:8:9
    |
@@ -33,7 +33,7 @@ error[E0275]: overflow evaluating the requirement `NoData<NoData<NoData<NoData<N
 LL | impl<T> Foo for T where NoData<T>: Foo {
    |                                    ^^^
    |
-   = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`issue_20413`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_20413`)
 note: required because of the requirements on the impl of `Foo` for `NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<T>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>`
   --> $DIR/issue-20413.rs:8:9
    |
@@ -53,7 +53,7 @@ error[E0275]: overflow evaluating the requirement `EvenLessData<AlmostNoData<Eve
 LL | impl<T> Bar for T where EvenLessData<T>: Baz {
    |                                          ^^^
    |
-   = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`issue_20413`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_20413`)
 note: required because of the requirements on the impl of `Bar` for `AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<T>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>`
   --> $DIR/issue-20413.rs:28:9
    |
@@ -78,7 +78,7 @@ error[E0275]: overflow evaluating the requirement `EvenLessData<AlmostNoData<Eve
 LL | impl<T> Bar for T where EvenLessData<T>: Baz {
    |                                          ^^^
    |
-   = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`issue_20413`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_20413`)
 note: required because of the requirements on the impl of `Bar` for `AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<T>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>`
   --> $DIR/issue-20413.rs:28:9
    |
@@ -103,7 +103,7 @@ error[E0275]: overflow evaluating the requirement `AlmostNoData<EvenLessData<Alm
 LL | impl<T> Baz for T where AlmostNoData<T>: Bar {
    |                                          ^^^
    |
-   = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`issue_20413`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_20413`)
 note: required because of the requirements on the impl of `Baz` for `EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<T>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>`
   --> $DIR/issue-20413.rs:36:9
    |
@@ -128,7 +128,7 @@ error[E0275]: overflow evaluating the requirement `AlmostNoData<EvenLessData<Alm
 LL | impl<T> Baz for T where AlmostNoData<T>: Bar {
    |                                          ^^^
    |
-   = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`issue_20413`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_20413`)
 note: required because of the requirements on the impl of `Baz` for `EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<T>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>`
   --> $DIR/issue-20413.rs:36:9
    |
diff --git a/src/test/ui/issues/issue-21600.stderr b/src/test/ui/issues/issue-21600.stderr
index 84c7106e890..dab3c3d1797 100644
--- a/src/test/ui/issues/issue-21600.stderr
+++ b/src/test/ui/issues/issue-21600.stderr
@@ -5,7 +5,7 @@ LL | fn call_it<F>(f: F) where F: Fn() { f(); }
    |                  - change this to accept `FnMut` instead of `Fn`
 ...
 LL |         call_it(|| x.gen_mut());
-   |         -------    ^ cannot borrow as mutable
+   |         -------    ^^^^^^^^^^^ cannot borrow as mutable
    |         |
    |         expects `Fn` instead of `FnMut`
 
diff --git a/src/test/ui/issues/issue-23122-2.stderr b/src/test/ui/issues/issue-23122-2.stderr
index 68a95dc265e..b345e901787 100644
--- a/src/test/ui/issues/issue-23122-2.stderr
+++ b/src/test/ui/issues/issue-23122-2.stderr
@@ -4,7 +4,7 @@ error[E0275]: overflow evaluating the requirement `<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
 LL |     type Next = <GetNext<T::Next> as Next>::Next;
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`issue_23122_2`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_23122_2`)
 note: required because of the requirements on the impl of `Next` for `GetNext<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<T as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next>`
   --> $DIR/issue-23122-2.rs:8:15
    |
diff --git a/src/test/ui/issues/issue-41726.stderr b/src/test/ui/issues/issue-41726.stderr
index b00a420bc37..22631e7c2a3 100644
--- a/src/test/ui/issues/issue-41726.stderr
+++ b/src/test/ui/issues/issue-41726.stderr
@@ -2,7 +2,7 @@ error[E0596]: cannot borrow data in an index of `HashMap<String, Vec<String>>` a
   --> $DIR/issue-41726.rs:5:9
    |
 LL |         things[src.as_str()].sort();
-   |         ^^^^^^^^^^^^^^^^^^^^ cannot borrow as mutable
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot borrow as mutable
    |
    = help: trait `IndexMut` is required to modify indexed content, but it is not implemented for `HashMap<String, Vec<String>>`
 
diff --git a/src/test/ui/issues/issue-42106.stderr b/src/test/ui/issues/issue-42106.stderr
index d5a9d233bc9..73cf8652f6d 100644
--- a/src/test/ui/issues/issue-42106.stderr
+++ b/src/test/ui/issues/issue-42106.stderr
@@ -4,9 +4,9 @@ error[E0502]: cannot borrow `*collection` as mutable because it is also borrowed
 LL |     let _a = &collection;
    |              ----------- immutable borrow occurs here
 LL |     collection.swap(1, 2);
-   |     ^^^^^^^^^^ mutable borrow occurs here
+   |     ^^^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
 LL |     _a.use_ref();
-   |     -- immutable borrow later used here
+   |     ------------ immutable borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-44405.stderr b/src/test/ui/issues/issue-44405.stderr
index 1fd69f6e777..626cb2999e1 100644
--- a/src/test/ui/issues/issue-44405.stderr
+++ b/src/test/ui/issues/issue-44405.stderr
@@ -2,7 +2,7 @@ error[E0596]: cannot borrow data in an index of `Container` as mutable
   --> $DIR/issue-44405.rs:21:5
    |
 LL |     container[&mut val].test();
-   |     ^^^^^^^^^^^^^^^^^^^ cannot borrow as mutable
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot borrow as mutable
    |
    = help: trait `IndexMut` is required to modify indexed content, but it is not implemented for `Container`
 
diff --git a/src/test/ui/issues/issue-47646.stderr b/src/test/ui/issues/issue-47646.stderr
index b46c277d045..eff1de3e017 100644
--- a/src/test/ui/issues/issue-47646.stderr
+++ b/src/test/ui/issues/issue-47646.stderr
@@ -2,7 +2,7 @@ error[E0502]: cannot borrow `heap` as immutable because it is also borrowed as m
   --> $DIR/issue-47646.rs:9:30
    |
 LL |     let borrow = heap.peek_mut();
-   |                  ---- mutable borrow occurs here
+   |                  --------------- mutable borrow occurs here
 LL | 
 LL |     match (borrow, ()) {
    |           ------------ a temporary with access to the mutable borrow is created here ...
diff --git a/src/test/ui/issues/issue-52126-assign-op-invariance.stderr b/src/test/ui/issues/issue-52126-assign-op-invariance.stderr
index d231f621e59..d4506757762 100644
--- a/src/test/ui/issues/issue-52126-assign-op-invariance.stderr
+++ b/src/test/ui/issues/issue-52126-assign-op-invariance.stderr
@@ -2,7 +2,7 @@ error[E0597]: `line` does not live long enough
   --> $DIR/issue-52126-assign-op-invariance.rs:34:28
    |
 LL |         let v: Vec<&str> = line.split_whitespace().collect();
-   |                            ^^^^ borrowed value does not live long enough
+   |                            ^^^^^^^^^^^^^^^^^^^^^^^ borrowed value does not live long enough
 ...
 LL |         acc += cnt2;
    |         --- borrow later used here
diff --git a/src/test/ui/issues/issue-61108.stderr b/src/test/ui/issues/issue-61108.stderr
index fb242f738c8..6f345f56d1a 100644
--- a/src/test/ui/issues/issue-61108.stderr
+++ b/src/test/ui/issues/issue-61108.stderr
@@ -10,7 +10,7 @@ LL |     for l in bad_letters {
    |              help: consider borrowing to avoid moving into the for loop: `&bad_letters`
 ...
 LL |     bad_letters.push('s');
-   |     ^^^^^^^^^^^ value borrowed here after move
+   |     ^^^^^^^^^^^^^^^^^^^^^ value borrowed here after move
    |
 note: this function takes ownership of the receiver `self`, which moves `bad_letters`
   --> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
diff --git a/src/test/ui/issues/issue-81584.stderr b/src/test/ui/issues/issue-81584.stderr
index d57f1b778df..54973cfa34e 100644
--- a/src/test/ui/issues/issue-81584.stderr
+++ b/src/test/ui/issues/issue-81584.stderr
@@ -2,7 +2,7 @@ error[E0515]: cannot return value referencing function parameter `y`
   --> $DIR/issue-81584.rs:5:22
    |
 LL |             .map(|y| y.iter().map(|x| x + 1))
-   |                      -^^^^^^^^^^^^^^^^^^^^^^
+   |                      --------^^^^^^^^^^^^^^^
    |                      |
    |                      returns a value referencing data owned by the current function
    |                      `y` is borrowed here
diff --git a/src/test/ui/lang-items/lang-item-generic-requirements.rs b/src/test/ui/lang-items/lang-item-generic-requirements.rs
index d785749afc9..c0b958f2bf2 100644
--- a/src/test/ui/lang-items/lang-item-generic-requirements.rs
+++ b/src/test/ui/lang-items/lang-item-generic-requirements.rs
@@ -1,9 +1,8 @@
-// Checks whether declaring a lang item with the wrong number
-// of generic arguments crashes the compiler (issue #83893, #87573, and part of #9307).
+// Checks that declaring a lang item with the wrong number
+// of generic arguments errors rather than crashing (issue #83893, #87573, part of #9307, #79559).
 
 #![feature(lang_items, no_core)]
 #![no_core]
-#![crate_type = "lib"]
 
 #[lang = "sized"]
 trait MySized {}
@@ -26,6 +25,14 @@ struct MyPhantomData<T, U>;
 //~^ ERROR parameter `T` is never used
 //~| ERROR parameter `U` is never used
 
+// When the `start` lang item is missing generics very odd things can happen, especially when
+// it comes to cross-crate monomorphization
+#[lang = "start"]
+//~^ ERROR `start` language item must be applied to a function with 1 generic argument [E0718]
+fn start(_: *const u8, _: isize, _: *const *const u8) -> isize {
+    0
+}
+
 fn ice() {
     // Use add
     let r = 5;
@@ -42,3 +49,6 @@ fn ice() {
     // Use phantomdata
     let _ = MyPhantomData::<(), i32>;
 }
+
+// use `start`
+fn main() {}
diff --git a/src/test/ui/lang-items/lang-item-generic-requirements.stderr b/src/test/ui/lang-items/lang-item-generic-requirements.stderr
index add5938811c..df5a77850f1 100644
--- a/src/test/ui/lang-items/lang-item-generic-requirements.stderr
+++ b/src/test/ui/lang-items/lang-item-generic-requirements.stderr
@@ -1,5 +1,5 @@
 error[E0718]: `add` language item must be applied to a trait with 1 generic argument
-  --> $DIR/lang-item-generic-requirements.rs:11:1
+  --> $DIR/lang-item-generic-requirements.rs:10:1
    |
 LL | #[lang = "add"]
    | ^^^^^^^^^^^^^^^
@@ -7,7 +7,7 @@ LL | trait MyAdd<'a, T> {}
    |            ------- this trait has 2 generic arguments
 
 error[E0718]: `drop_in_place` language item must be applied to a function with at least 1 generic argument
-  --> $DIR/lang-item-generic-requirements.rs:15:1
+  --> $DIR/lang-item-generic-requirements.rs:14:1
    |
 LL | #[lang = "drop_in_place"]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -16,7 +16,7 @@ LL | fn my_ptr_drop() {}
    |               - this function has 0 generic arguments
 
 error[E0718]: `index` language item must be applied to a trait with 1 generic argument
-  --> $DIR/lang-item-generic-requirements.rs:19:1
+  --> $DIR/lang-item-generic-requirements.rs:18:1
    |
 LL | #[lang = "index"]
    | ^^^^^^^^^^^^^^^^^
@@ -24,7 +24,7 @@ LL | trait MyIndex<'a, T> {}
    |              ------- this trait has 2 generic arguments
 
 error[E0718]: `phantom_data` language item must be applied to a struct with 1 generic argument
-  --> $DIR/lang-item-generic-requirements.rs:23:1
+  --> $DIR/lang-item-generic-requirements.rs:22:1
    |
 LL | #[lang = "phantom_data"]
    | ^^^^^^^^^^^^^^^^^^^^^^^^
@@ -32,8 +32,17 @@ LL |
 LL | struct MyPhantomData<T, U>;
    |                     ------ this struct has 2 generic arguments
 
+error[E0718]: `start` language item must be applied to a function with 1 generic argument
+  --> $DIR/lang-item-generic-requirements.rs:30:1
+   |
+LL | #[lang = "start"]
+   | ^^^^^^^^^^^^^^^^^
+LL |
+LL | fn start(_: *const u8, _: isize, _: *const *const u8) -> isize {
+   |         - this function has 0 generic arguments
+
 error[E0392]: parameter `T` is never used
-  --> $DIR/lang-item-generic-requirements.rs:25:22
+  --> $DIR/lang-item-generic-requirements.rs:24:22
    |
 LL | struct MyPhantomData<T, U>;
    |                      ^ unused parameter
@@ -42,7 +51,7 @@ LL | struct MyPhantomData<T, U>;
    = help: if you intended `T` to be a const parameter, use `const T: usize` instead
 
 error[E0392]: parameter `U` is never used
-  --> $DIR/lang-item-generic-requirements.rs:25:25
+  --> $DIR/lang-item-generic-requirements.rs:24:25
    |
 LL | struct MyPhantomData<T, U>;
    |                         ^ unused parameter
@@ -50,7 +59,7 @@ LL | struct MyPhantomData<T, U>;
    = help: consider removing `U` or referring to it in a field
    = help: if you intended `U` to be a const parameter, use `const U: usize` instead
 
-error: aborting due to 6 previous errors
+error: aborting due to 7 previous errors
 
 Some errors have detailed explanations: E0392, E0718.
 For more information about an error, try `rustc --explain E0392`.
diff --git a/src/test/ui/lifetimes/borrowck-let-suggestion.stderr b/src/test/ui/lifetimes/borrowck-let-suggestion.stderr
index 4a605cfb862..bbf04c98436 100644
--- a/src/test/ui/lifetimes/borrowck-let-suggestion.stderr
+++ b/src/test/ui/lifetimes/borrowck-let-suggestion.stderr
@@ -7,7 +7,7 @@ LL |     let mut x = vec![1].iter();
    |                 creates a temporary which is freed while still in use
 LL |
 LL |     x.use_mut();
-   |     - borrow later used here
+   |     ----------- borrow later used here
    |
    = note: consider using a `let` binding to create a longer lived value
    = note: this error originates in the macro `vec` (in Nightly builds, run with -Z macro-backtrace for more info)
diff --git a/src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-using-fn-items.nll.stderr b/src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-using-fn-items.nll.stderr
index 33be98c6491..825c45b2434 100644
--- a/src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-using-fn-items.nll.stderr
+++ b/src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-using-fn-items.nll.stderr
@@ -1,11 +1,3 @@
-error[E0596]: cannot borrow `y` as mutable, as it is not declared as mutable
-  --> $DIR/ex3-both-anon-regions-using-fn-items.rs:2:3
-   |
-LL | fn foo(x:fn(&u8, &u8), y: Vec<&u8>, z: &u8) {
-   |                        - help: consider changing this to be mutable: `mut y`
-LL |   y.push(z);
-   |   ^ cannot borrow as mutable
-
 error: lifetime may not live long enough
   --> $DIR/ex3-both-anon-regions-using-fn-items.rs:2:3
    |
@@ -16,6 +8,14 @@ LL | fn foo(x:fn(&u8, &u8), y: Vec<&u8>, z: &u8) {
 LL |   y.push(z);
    |   ^^^^^^^^^ argument requires that `'1` must outlive `'2`
 
+error[E0596]: cannot borrow `y` as mutable, as it is not declared as mutable
+  --> $DIR/ex3-both-anon-regions-using-fn-items.rs:2:3
+   |
+LL | fn foo(x:fn(&u8, &u8), y: Vec<&u8>, z: &u8) {
+   |                        - help: consider changing this to be mutable: `mut y`
+LL |   y.push(z);
+   |   ^^^^^^^^^ cannot borrow as mutable
+
 error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0596`.
diff --git a/src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-using-trait-objects.nll.stderr b/src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-using-trait-objects.nll.stderr
index 3c95be95db0..78a828dde86 100644
--- a/src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-using-trait-objects.nll.stderr
+++ b/src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-using-trait-objects.nll.stderr
@@ -1,11 +1,3 @@
-error[E0596]: cannot borrow `y` as mutable, as it is not declared as mutable
-  --> $DIR/ex3-both-anon-regions-using-trait-objects.rs:2:3
-   |
-LL | fn foo(x:Box<dyn Fn(&u8, &u8)> , y: Vec<&u8>, z: &u8) {
-   |                                  - help: consider changing this to be mutable: `mut y`
-LL |   y.push(z);
-   |   ^ cannot borrow as mutable
-
 error: lifetime may not live long enough
   --> $DIR/ex3-both-anon-regions-using-trait-objects.rs:2:3
    |
@@ -16,6 +8,14 @@ LL | fn foo(x:Box<dyn Fn(&u8, &u8)> , y: Vec<&u8>, z: &u8) {
 LL |   y.push(z);
    |   ^^^^^^^^^ argument requires that `'1` must outlive `'2`
 
+error[E0596]: cannot borrow `y` as mutable, as it is not declared as mutable
+  --> $DIR/ex3-both-anon-regions-using-trait-objects.rs:2:3
+   |
+LL | fn foo(x:Box<dyn Fn(&u8, &u8)> , y: Vec<&u8>, z: &u8) {
+   |                                  - help: consider changing this to be mutable: `mut y`
+LL |   y.push(z);
+   |   ^^^^^^^^^ cannot borrow as mutable
+
 error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0596`.
diff --git a/src/test/ui/lint/must_not_suspend/mutex.rs b/src/test/ui/lint/must_not_suspend/mutex.rs
new file mode 100644
index 00000000000..596249b2e4e
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/mutex.rs
@@ -0,0 +1,12 @@
+// edition:2018
+#![deny(must_not_suspend)]
+
+async fn other() {}
+
+pub async fn uhoh(m: std::sync::Mutex<()>) {
+    let _guard = m.lock().unwrap(); //~ ERROR `MutexGuard` held across
+    other().await;
+}
+
+fn main() {
+}
diff --git a/src/test/ui/lint/must_not_suspend/mutex.stderr b/src/test/ui/lint/must_not_suspend/mutex.stderr
new file mode 100644
index 00000000000..4e0d9343c2c
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/mutex.stderr
@@ -0,0 +1,26 @@
+error: `MutexGuard` held across a suspend point, but should not be
+  --> $DIR/mutex.rs:7:9
+   |
+LL |     let _guard = m.lock().unwrap();
+   |         ^^^^^^
+LL |     other().await;
+   |     ------------- the value is held across this suspend point
+   |
+note: the lint level is defined here
+  --> $DIR/mutex.rs:2:9
+   |
+LL | #![deny(must_not_suspend)]
+   |         ^^^^^^^^^^^^^^^^
+note: Holding a MutexGuard across suspend points can cause deadlocks, delays, and cause Futures to not implement `Send`
+  --> $DIR/mutex.rs:7:9
+   |
+LL |     let _guard = m.lock().unwrap();
+   |         ^^^^^^
+help: consider using a block (`{ ... }`) to shrink the value's scope, ending before the suspend point
+  --> $DIR/mutex.rs:7:9
+   |
+LL |     let _guard = m.lock().unwrap();
+   |         ^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/lint/unaligned_references.stderr b/src/test/ui/lint/unaligned_references.stderr
index b4cce3cfea2..6a5cc91963d 100644
--- a/src/test/ui/lint/unaligned_references.stderr
+++ b/src/test/ui/lint/unaligned_references.stderr
@@ -47,7 +47,7 @@ error: reference to packed field is unaligned
   --> $DIR/unaligned_references.rs:32:17
    |
 LL |         let _ = good.data.clone();
-   |                 ^^^^^^^^^
+   |                 ^^^^^^^^^^^^^^^^^
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #82523 <https://github.com/rust-lang/rust/issues/82523>
diff --git a/src/test/ui/lub-glb/old-lub-glb-hr-noteq1.nll.stderr b/src/test/ui/lub-glb/old-lub-glb-hr-noteq1.nll.stderr
index 3fdc2da9f1e..5ac392914e5 100644
--- a/src/test/ui/lub-glb/old-lub-glb-hr-noteq1.nll.stderr
+++ b/src/test/ui/lub-glb/old-lub-glb-hr-noteq1.nll.stderr
@@ -4,8 +4,8 @@ error[E0308]: mismatched types
 LL |         _ => y,
    |              ^ one type is more general than the other
    |
-   = note: expected fn pointer `for<'r, 's> fn(&'r u8, &'s u8) -> &'r u8`
-              found fn pointer `for<'r> fn(&'r u8, &'r u8) -> &'r u8`
+   = note: expected fn pointer `for<'a, 'b> fn(&'a u8, &'b u8) -> &'a u8`
+              found fn pointer `for<'a> fn(&'a u8, &'a u8) -> &'a u8`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/lub-glb/old-lub-glb-object.nll.stderr b/src/test/ui/lub-glb/old-lub-glb-object.nll.stderr
index ad14d6b7521..355f0754ab1 100644
--- a/src/test/ui/lub-glb/old-lub-glb-object.nll.stderr
+++ b/src/test/ui/lub-glb/old-lub-glb-object.nll.stderr
@@ -4,8 +4,8 @@ error[E0308]: mismatched types
 LL |         _ => y,
    |              ^ one type is more general than the other
    |
-   = note: expected trait object `dyn for<'r, 's> Foo<&'r u8, &'s u8>`
-              found trait object `dyn for<'r> Foo<&'r u8, &'r u8>`
+   = note: expected trait object `dyn for<'a, 'b> Foo<&'a u8, &'b u8>`
+              found trait object `dyn for<'a> Foo<&'a u8, &'a u8>`
 
 error[E0308]: mismatched types
   --> $DIR/old-lub-glb-object.rs:10:14
@@ -13,8 +13,8 @@ error[E0308]: mismatched types
 LL |         _ => y,
    |              ^ one type is more general than the other
    |
-   = note: expected trait object `dyn for<'r, 's> Foo<&'r u8, &'s u8>`
-              found trait object `dyn for<'r> Foo<&'r u8, &'r u8>`
+   = note: expected trait object `dyn for<'a, 'b> Foo<&'a u8, &'b u8>`
+              found trait object `dyn for<'a> Foo<&'a u8, &'a u8>`
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/macros/issue-84632-eager-expansion-recursion-limit.rs b/src/test/ui/macros/issue-84632-eager-expansion-recursion-limit.rs
index 9139775c805..7a1e62d49d3 100644
--- a/src/test/ui/macros/issue-84632-eager-expansion-recursion-limit.rs
+++ b/src/test/ui/macros/issue-84632-eager-expansion-recursion-limit.rs
@@ -7,7 +7,7 @@ macro_rules! a {
     (A) => (concat!("", a!()));
     (A, $($A:ident),*) => (concat!("", a!($($A),*)))
     //~^ ERROR recursion limit reached
-    //~| HELP consider adding
+    //~| HELP consider increasing the recursion limit
 }
 
 fn main() {
diff --git a/src/test/ui/macros/issue-84632-eager-expansion-recursion-limit.stderr b/src/test/ui/macros/issue-84632-eager-expansion-recursion-limit.stderr
index e6067e33349..aa7d33cfd11 100644
--- a/src/test/ui/macros/issue-84632-eager-expansion-recursion-limit.stderr
+++ b/src/test/ui/macros/issue-84632-eager-expansion-recursion-limit.stderr
@@ -7,7 +7,7 @@ LL |     (A, $($A:ident),*) => (concat!("", a!($($A),*)))
 LL |     a!(A, A, A, A, A, A, A, A, A, A, A);
    |     ------------------------------------ in this macro invocation
    |
-   = help: consider adding a `#![recursion_limit="30"]` attribute to your crate (`issue_84632_eager_expansion_recursion_limit`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "30"]` attribute to your crate (`issue_84632_eager_expansion_recursion_limit`)
    = note: this error originates in the macro `a` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to previous error
diff --git a/src/test/ui/macros/trace_faulty_macros.stderr b/src/test/ui/macros/trace_faulty_macros.stderr
index 38affde5f6c..dc38972d1d0 100644
--- a/src/test/ui/macros/trace_faulty_macros.stderr
+++ b/src/test/ui/macros/trace_faulty_macros.stderr
@@ -31,7 +31,7 @@ LL |         my_recursive_macro!();
 LL |     my_recursive_macro!();
    |     ---------------------- in this macro invocation
    |
-   = help: consider adding a `#![recursion_limit="8"]` attribute to your crate (`trace_faulty_macros`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "8"]` attribute to your crate (`trace_faulty_macros`)
    = note: this error originates in the macro `my_recursive_macro` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 note: trace_macro
diff --git a/src/test/ui/match/issue-74050-end-span.stderr b/src/test/ui/match/issue-74050-end-span.stderr
index d636a11a91c..59c091e44eb 100644
--- a/src/test/ui/match/issue-74050-end-span.stderr
+++ b/src/test/ui/match/issue-74050-end-span.stderr
@@ -5,7 +5,7 @@ LL |     let _arg = match args.next() {
    |         ---- borrow later stored here
 LL |         Some(arg) => {
 LL |             match arg.to_str() {
-   |                   ^^^ borrowed value does not live long enough
+   |                   ^^^^^^^^^^^^ borrowed value does not live long enough
 ...
 LL |         }
    |         - `arg` dropped here while still borrowed
diff --git a/src/test/ui/maybe-bounds-where.stderr b/src/test/ui/maybe-bounds-where.stderr
index 2aa6a8a3822..39bc1b88e56 100644
--- a/src/test/ui/maybe-bounds-where.stderr
+++ b/src/test/ui/maybe-bounds-where.stderr
@@ -1,32 +1,32 @@
 error: `?Trait` bounds are only permitted at the point where a type parameter is declared
-  --> $DIR/maybe-bounds-where.rs:1:23
+  --> $DIR/maybe-bounds-where.rs:1:28
    |
 LL | struct S1<T>(T) where (T): ?Sized;
-   |                       ^^^
+   |                            ^^^^^^
 
 error: `?Trait` bounds are only permitted at the point where a type parameter is declared
-  --> $DIR/maybe-bounds-where.rs:4:23
+  --> $DIR/maybe-bounds-where.rs:4:27
    |
 LL | struct S2<T>(T) where u8: ?Sized;
-   |                       ^^
+   |                           ^^^^^^
 
 error: `?Trait` bounds are only permitted at the point where a type parameter is declared
-  --> $DIR/maybe-bounds-where.rs:7:23
+  --> $DIR/maybe-bounds-where.rs:7:35
    |
 LL | struct S3<T>(T) where &'static T: ?Sized;
-   |                       ^^^^^^^^^^
+   |                                   ^^^^^^
 
 error: `?Trait` bounds are only permitted at the point where a type parameter is declared
-  --> $DIR/maybe-bounds-where.rs:12:31
+  --> $DIR/maybe-bounds-where.rs:12:34
    |
 LL | struct S4<T>(T) where for<'a> T: ?Trait<'a>;
-   |                               ^
+   |                                  ^^^^^^^^^^
 
 error: `?Trait` bounds are only permitted at the point where a type parameter is declared
-  --> $DIR/maybe-bounds-where.rs:21:18
+  --> $DIR/maybe-bounds-where.rs:21:21
    |
 LL |     fn f() where T: ?Sized {}
-   |                  ^
+   |                     ^^^^^^
 
 warning: default bound relaxed for a type parameter, but this does nothing because the given bound is not a default; only `?Sized` is supported
   --> $DIR/maybe-bounds-where.rs:12:11
diff --git a/src/test/ui/methods/method-ambig-two-traits-from-impls2.stderr b/src/test/ui/methods/method-ambig-two-traits-from-impls2.stderr
index e0a58aed8f4..4ba778e0ef7 100644
--- a/src/test/ui/methods/method-ambig-two-traits-from-impls2.stderr
+++ b/src/test/ui/methods/method-ambig-two-traits-from-impls2.stderr
@@ -16,12 +16,12 @@ LL |     fn foo() {}
    |     ^^^^^^^^
 help: disambiguate the associated function for candidate #1
    |
-LL |     A::foo();
-   |     ~~~
+LL |     <AB as A>::foo();
+   |     ~~~~~~~~~~~
 help: disambiguate the associated function for candidate #2
    |
-LL |     B::foo();
-   |     ~~~
+LL |     <AB as B>::foo();
+   |     ~~~~~~~~~~~
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/methods/method-self-arg-2.stderr b/src/test/ui/methods/method-self-arg-2.stderr
index 946e71ee5b9..b98f7a78661 100644
--- a/src/test/ui/methods/method-self-arg-2.stderr
+++ b/src/test/ui/methods/method-self-arg-2.stderr
@@ -6,7 +6,7 @@ LL |     let y = &mut x;
 LL |     Foo::bar(&x);
    |              ^^ immutable borrow occurs here
 LL |     y.use_mut();
-   |     - mutable borrow later used here
+   |     ----------- mutable borrow later used here
 
 error[E0499]: cannot borrow `x` as mutable more than once at a time
   --> $DIR/method-self-arg-2.rs:20:14
@@ -16,7 +16,7 @@ LL |     let y = &mut x;
 LL |     Foo::baz(&mut x);
    |              ^^^^^^ second mutable borrow occurs here
 LL |     y.use_mut();
-   |     - first borrow later used here
+   |     ----------- first borrow later used here
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/moves/issue-72649-uninit-in-loop.rs b/src/test/ui/moves/issue-72649-uninit-in-loop.rs
new file mode 100644
index 00000000000..e6bc4e22ec2
--- /dev/null
+++ b/src/test/ui/moves/issue-72649-uninit-in-loop.rs
@@ -0,0 +1,74 @@
+// Regression test for issue #72649
+// Tests that we don't emit spurious
+// 'value moved in previous iteration of loop' message
+
+struct NonCopy;
+
+fn good() {
+    loop {
+        let value = NonCopy{};
+        let _used = value;
+    }
+}
+
+fn moved_here_1() {
+    loop {
+        let value = NonCopy{};
+        //~^ NOTE move occurs because `value` has type `NonCopy`, which does not implement the `Copy` trait
+        let _used = value;
+        //~^ NOTE value moved here
+        let _used2 = value; //~ ERROR use of moved value: `value`
+        //~^ NOTE value used here after move
+    }
+}
+
+fn moved_here_2() {
+    let value = NonCopy{};
+    //~^ NOTE move occurs because `value` has type `NonCopy`, which does not implement the `Copy` trait
+    loop {
+        let _used = value;
+        //~^ NOTE value moved here
+        loop {
+            let _used2 = value; //~ ERROR use of moved value: `value`
+            //~^ NOTE value used here after move
+        }
+    }
+}
+
+fn moved_loop_1() {
+    let value = NonCopy{};
+    //~^ NOTE move occurs because `value` has type `NonCopy`, which does not implement the `Copy` trait
+    loop {
+        let _used = value; //~ ERROR use of moved value: `value`
+        //~^ NOTE value moved here, in previous iteration of loop
+    }
+}
+
+fn moved_loop_2() {
+    let mut value = NonCopy{};
+    //~^ NOTE move occurs because `value` has type `NonCopy`, which does not implement the `Copy` trait
+    let _used = value;
+    value = NonCopy{};
+    loop {
+        let _used2 = value; //~ ERROR use of moved value: `value`
+        //~^ NOTE value moved here, in previous iteration of loop
+    }
+}
+
+fn uninit_1() {
+    loop {
+        let value: NonCopy;
+        let _used = value; //~ ERROR use of possibly-uninitialized variable: `value`
+        //~^ NOTE use of possibly-uninitialized `value`
+    }
+}
+
+fn uninit_2() {
+    let mut value: NonCopy;
+    loop {
+        let _used = value; //~ ERROR use of possibly-uninitialized variable: `value`
+        //~^ NOTE use of possibly-uninitialized `value`
+    }
+}
+
+fn main() {}
diff --git a/src/test/ui/moves/issue-72649-uninit-in-loop.stderr b/src/test/ui/moves/issue-72649-uninit-in-loop.stderr
new file mode 100644
index 00000000000..076d3dff140
--- /dev/null
+++ b/src/test/ui/moves/issue-72649-uninit-in-loop.stderr
@@ -0,0 +1,58 @@
+error[E0382]: use of moved value: `value`
+  --> $DIR/issue-72649-uninit-in-loop.rs:20:22
+   |
+LL |         let value = NonCopy{};
+   |             ----- move occurs because `value` has type `NonCopy`, which does not implement the `Copy` trait
+LL |
+LL |         let _used = value;
+   |                     ----- value moved here
+LL |
+LL |         let _used2 = value;
+   |                      ^^^^^ value used here after move
+
+error[E0382]: use of moved value: `value`
+  --> $DIR/issue-72649-uninit-in-loop.rs:32:26
+   |
+LL |     let value = NonCopy{};
+   |         ----- move occurs because `value` has type `NonCopy`, which does not implement the `Copy` trait
+...
+LL |         let _used = value;
+   |                     ----- value moved here
+...
+LL |             let _used2 = value;
+   |                          ^^^^^ value used here after move
+
+error[E0382]: use of moved value: `value`
+  --> $DIR/issue-72649-uninit-in-loop.rs:42:21
+   |
+LL |     let value = NonCopy{};
+   |         ----- move occurs because `value` has type `NonCopy`, which does not implement the `Copy` trait
+...
+LL |         let _used = value;
+   |                     ^^^^^ value moved here, in previous iteration of loop
+
+error[E0382]: use of moved value: `value`
+  --> $DIR/issue-72649-uninit-in-loop.rs:53:22
+   |
+LL |     let mut value = NonCopy{};
+   |         --------- move occurs because `value` has type `NonCopy`, which does not implement the `Copy` trait
+...
+LL |         let _used2 = value;
+   |                      ^^^^^ value moved here, in previous iteration of loop
+
+error[E0381]: use of possibly-uninitialized variable: `value`
+  --> $DIR/issue-72649-uninit-in-loop.rs:61:21
+   |
+LL |         let _used = value;
+   |                     ^^^^^ use of possibly-uninitialized `value`
+
+error[E0381]: use of possibly-uninitialized variable: `value`
+  --> $DIR/issue-72649-uninit-in-loop.rs:69:21
+   |
+LL |         let _used = value;
+   |                     ^^^^^ use of possibly-uninitialized `value`
+
+error: aborting due to 6 previous errors
+
+Some errors have detailed explanations: E0381, E0382.
+For more information about an error, try `rustc --explain E0381`.
diff --git a/src/test/ui/moves/move-fn-self-receiver.stderr b/src/test/ui/moves/move-fn-self-receiver.stderr
index eca6bb9296d..57be5fb4d8a 100644
--- a/src/test/ui/moves/move-fn-self-receiver.stderr
+++ b/src/test/ui/moves/move-fn-self-receiver.stderr
@@ -75,7 +75,7 @@ error[E0505]: cannot move out of `mut_foo` because it is borrowed
   --> $DIR/move-fn-self-receiver.rs:50:5
    |
 LL |     let ret = mut_foo.use_mut_self();
-   |               ------- borrow of `mut_foo` occurs here
+   |               ---------------------- borrow of `mut_foo` occurs here
 LL |     mut_foo;
    |     ^^^^^^^ move out of `mut_foo` occurs here
 LL |     ret;
diff --git a/src/test/ui/mut/mut-cant-alias.stderr b/src/test/ui/mut/mut-cant-alias.stderr
index d56e45db13d..6046c076f2e 100644
--- a/src/test/ui/mut/mut-cant-alias.stderr
+++ b/src/test/ui/mut/mut-cant-alias.stderr
@@ -6,7 +6,7 @@ LL |     let b1 = &mut *b;
 LL |     let b2 = &mut *b;
    |                    ^ second mutable borrow occurs here
 LL |     b1.use_mut();
-   |     -- first borrow later used here
+   |     ------------ first borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/mut/mut-suggestion.stderr b/src/test/ui/mut/mut-suggestion.stderr
index 245eaff4bb4..cba284550b9 100644
--- a/src/test/ui/mut/mut-suggestion.stderr
+++ b/src/test/ui/mut/mut-suggestion.stderr
@@ -5,7 +5,7 @@ LL | fn func(arg: S) {
    |         --- help: consider changing this to be mutable: `mut arg`
 ...
 LL |     arg.mutate();
-   |     ^^^ cannot borrow as mutable
+   |     ^^^^^^^^^^^^ cannot borrow as mutable
 
 error[E0596]: cannot borrow `local` as mutable, as it is not declared as mutable
   --> $DIR/mut-suggestion.rs:20:5
@@ -14,7 +14,7 @@ LL |     let local = S;
    |         ----- help: consider changing this to be mutable: `mut local`
 ...
 LL |     local.mutate();
-   |     ^^^^^ cannot borrow as mutable
+   |     ^^^^^^^^^^^^^^ cannot borrow as mutable
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/nll/closure-access-spans.stderr b/src/test/ui/nll/closure-access-spans.stderr
index 8eded8f2857..e9d7ca953d6 100644
--- a/src/test/ui/nll/closure-access-spans.stderr
+++ b/src/test/ui/nll/closure-access-spans.stderr
@@ -8,7 +8,7 @@ LL |     || x;
    |     |
    |     immutable borrow occurs here
 LL |     r.use_mut();
-   |     - mutable borrow later used here
+   |     ----------- mutable borrow later used here
 
 error[E0499]: cannot borrow `x` as mutable more than once at a time
   --> $DIR/closure-access-spans.rs:11:5
@@ -20,7 +20,7 @@ LL |     || x = 2;
    |     |
    |     second mutable borrow occurs here
 LL |     r.use_mut();
-   |     - first borrow later used here
+   |     ----------- first borrow later used here
 
 error[E0500]: closure requires unique access to `x` but it is already borrowed
   --> $DIR/closure-access-spans.rs:17:5
@@ -32,7 +32,7 @@ LL |     || *x = 2;
    |     |
    |     closure construction occurs here
 LL |     r.use_mut();
-   |     - first borrow later used here
+   |     ----------- first borrow later used here
 
 error[E0503]: cannot use `x` because it was mutably borrowed
   --> $DIR/closure-access-spans.rs:23:13
@@ -42,7 +42,7 @@ LL |     let r = &mut x;
 LL |     move || x;
    |             ^ use of borrowed `x`
 LL |     r.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error[E0505]: cannot move out of `x` because it is borrowed
   --> $DIR/closure-access-spans.rs:29:5
@@ -54,7 +54,7 @@ LL |     || x;
    |     |
    |     move out of `x` occurs here
 LL |     r.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error[E0382]: borrow of moved value: `x`
   --> $DIR/closure-access-spans.rs:35:5
diff --git a/src/test/ui/nll/closure-borrow-spans.stderr b/src/test/ui/nll/closure-borrow-spans.stderr
index fffbee4d4a8..bada4e1b84b 100644
--- a/src/test/ui/nll/closure-borrow-spans.stderr
+++ b/src/test/ui/nll/closure-borrow-spans.stderr
@@ -8,7 +8,7 @@ LL |     let f = || x.len();
 LL |     let y = x;
    |             ^ move out of `x` occurs here
 LL |     f.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error[E0502]: cannot borrow `x` as mutable because it is also borrowed as immutable
   --> $DIR/closure-borrow-spans.rs:11:13
@@ -20,7 +20,7 @@ LL |     let f = || x;
 LL |     let y = &mut x;
    |             ^^^^^^ mutable borrow occurs here
 LL |     f.use_ref();
-   |     - immutable borrow later used here
+   |     ----------- immutable borrow later used here
 
 error[E0597]: `x` does not live long enough
   --> $DIR/closure-borrow-spans.rs:19:16
@@ -32,7 +32,7 @@ LL |         f = || x;
 LL |     }
    |     - `x` dropped here while still borrowed
 LL |     f.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error[E0506]: cannot assign to `x` because it is borrowed
   --> $DIR/closure-borrow-spans.rs:26:5
@@ -44,7 +44,7 @@ LL |     let f = || x;
 LL |     x = 1;
    |     ^^^^^ assignment to borrowed `x` occurs here
 LL |     f.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error[E0503]: cannot use `x` because it was mutably borrowed
   --> $DIR/closure-borrow-spans.rs:32:13
@@ -56,7 +56,7 @@ LL |     let f = || x = 0;
 LL |     let y = x;
    |             ^ use of borrowed `x`
 LL |     f.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error[E0502]: cannot borrow `x` as immutable because it is also borrowed as mutable
   --> $DIR/closure-borrow-spans.rs:38:13
@@ -68,7 +68,7 @@ LL |     let f = || x = 0;
 LL |     let y = &x;
    |             ^^ immutable borrow occurs here
 LL |     f.use_ref();
-   |     - mutable borrow later used here
+   |     ----------- mutable borrow later used here
 
 error[E0499]: cannot borrow `x` as mutable more than once at a time
   --> $DIR/closure-borrow-spans.rs:44:13
@@ -80,7 +80,7 @@ LL |     let f = || x = 0;
 LL |     let y = &mut x;
    |             ^^^^^^ second mutable borrow occurs here
 LL |     f.use_ref();
-   |     - first borrow later used here
+   |     ----------- first borrow later used here
 
 error[E0597]: `x` does not live long enough
   --> $DIR/closure-borrow-spans.rs:52:16
@@ -92,7 +92,7 @@ LL |         f = || x = 0;
 LL |     }
    |     - `x` dropped here while still borrowed
 LL |     f.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error[E0506]: cannot assign to `x` because it is borrowed
   --> $DIR/closure-borrow-spans.rs:59:5
@@ -104,7 +104,7 @@ LL |     let f = || x = 0;
 LL |     x = 1;
    |     ^^^^^ assignment to borrowed `x` occurs here
 LL |     f.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error[E0505]: cannot move out of `x` because it is borrowed
   --> $DIR/closure-borrow-spans.rs:65:13
@@ -116,7 +116,7 @@ LL |     let f = || *x = 0;
 LL |     let y = x;
    |             ^ move out of `x` occurs here
 LL |     f.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error[E0501]: cannot borrow `x` as immutable because previous closure requires unique access
   --> $DIR/closure-borrow-spans.rs:71:13
@@ -128,7 +128,7 @@ LL |     let f = || *x = 0;
 LL |     let y = &x;
    |             ^^ second borrow occurs here
 LL |     f.use_ref();
-   |     - first borrow later used here
+   |     ----------- first borrow later used here
 
 error[E0501]: cannot borrow `x` as mutable because previous closure requires unique access
   --> $DIR/closure-borrow-spans.rs:77:13
@@ -140,7 +140,7 @@ LL |     let f = || *x = 0;
 LL |     let y = &mut x;
    |             ^^^^^^ second borrow occurs here
 LL |     f.use_ref();
-   |     - first borrow later used here
+   |     ----------- first borrow later used here
 
 error[E0597]: `x` does not live long enough
   --> $DIR/closure-borrow-spans.rs:86:16
@@ -152,7 +152,7 @@ LL |         f = || *x = 0;
 LL |     }
    |     - `x` dropped here while still borrowed
 LL |     f.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error[E0506]: cannot assign to `*x` because it is borrowed
   --> $DIR/closure-borrow-spans.rs:93:5
@@ -164,7 +164,7 @@ LL |     let f = || *x = 0;
 LL |     *x = 1;
    |     ^^^^^^ assignment to borrowed `*x` occurs here
 LL |     f.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error: aborting due to 14 previous errors
 
diff --git a/src/test/ui/nll/get_default.nll.stderr b/src/test/ui/nll/get_default.nll.stderr
deleted file mode 100644
index 27912306987..00000000000
--- a/src/test/ui/nll/get_default.nll.stderr
+++ /dev/null
@@ -1,48 +0,0 @@
-error[E0502]: cannot borrow `*map` as mutable because it is also borrowed as immutable
-  --> $DIR/get_default.rs:21:17
-   |
-LL | fn ok(map: &mut Map) -> &String {
-   |            - let's call the lifetime of this reference `'1`
-LL |     loop {
-LL |         match map.get() {
-   |               --- immutable borrow occurs here
-LL |             Some(v) => {
-LL |                 return v;
-   |                        - returning this value requires that `*map` is borrowed for `'1`
-...
-LL |                 map.set(String::new()); // Ideally, this would not error.
-   |                 ^^^ mutable borrow occurs here
-
-error[E0502]: cannot borrow `*map` as mutable because it is also borrowed as immutable
-  --> $DIR/get_default.rs:32:17
-   |
-LL | fn err(map: &mut Map) -> &String {
-   |             - let's call the lifetime of this reference `'1`
-LL |     loop {
-LL |         match map.get() {
-   |               --- immutable borrow occurs here
-LL |             Some(v) => {
-LL |                 map.set(String::new()); // Both AST and MIR error here
-   |                 ^^^ mutable borrow occurs here
-LL |
-LL |                 return v;
-   |                        - returning this value requires that `*map` is borrowed for `'1`
-
-error[E0502]: cannot borrow `*map` as mutable because it is also borrowed as immutable
-  --> $DIR/get_default.rs:37:17
-   |
-LL | fn err(map: &mut Map) -> &String {
-   |             - let's call the lifetime of this reference `'1`
-LL |     loop {
-LL |         match map.get() {
-   |               --- immutable borrow occurs here
-...
-LL |                 return v;
-   |                        - returning this value requires that `*map` is borrowed for `'1`
-...
-LL |                 map.set(String::new()); // Ideally, just AST would error here
-   |                 ^^^ mutable borrow occurs here
-
-error: aborting due to 3 previous errors
-
-For more information about this error, try `rustc --explain E0502`.
diff --git a/src/test/ui/nll/get_default.stderr b/src/test/ui/nll/get_default.stderr
index af79771e7e1..6998c04336e 100644
--- a/src/test/ui/nll/get_default.stderr
+++ b/src/test/ui/nll/get_default.stderr
@@ -5,7 +5,7 @@ LL | fn ok(map: &mut Map) -> &String {
    |            - let's call the lifetime of this reference `'1`
 LL |     loop {
 LL |         match map.get() {
-   |               --- immutable borrow occurs here
+   |               --------- immutable borrow occurs here
 LL |             Some(v) => {
 LL |                 return v;
    |                        - returning this value requires that `*map` is borrowed for `'1`
@@ -20,7 +20,7 @@ LL | fn err(map: &mut Map) -> &String {
    |             - let's call the lifetime of this reference `'1`
 LL |     loop {
 LL |         match map.get() {
-   |               --- immutable borrow occurs here
+   |               --------- immutable borrow occurs here
 LL |             Some(v) => {
 LL |                 map.set(String::new()); // Both AST and MIR error here
    |                 ^^^^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
@@ -35,7 +35,7 @@ LL | fn err(map: &mut Map) -> &String {
    |             - let's call the lifetime of this reference `'1`
 LL |     loop {
 LL |         match map.get() {
-   |               --- immutable borrow occurs here
+   |               --------- immutable borrow occurs here
 ...
 LL |                 return v;
    |                        - returning this value requires that `*map` is borrowed for `'1`
diff --git a/src/test/ui/nll/issue-46589.stderr b/src/test/ui/nll/issue-46589.stderr
index 82cd364eeff..60ef3f7b85e 100644
--- a/src/test/ui/nll/issue-46589.stderr
+++ b/src/test/ui/nll/issue-46589.stderr
@@ -2,10 +2,10 @@ error[E0499]: cannot borrow `**other` as mutable more than once at a time
   --> $DIR/issue-46589.rs:23:21
    |
 LL |         *other = match (*other).get_self() {
-   |                        -------- first mutable borrow occurs here
+   |                        ------------------- first mutable borrow occurs here
 LL |             Some(s) => s,
 LL |             None => (*other).new_self()
-   |                     ^^^^^^^^
+   |                     ^^^^^^^^^^^^^^^^^^^
    |                     |
    |                     second mutable borrow occurs here
    |                     first borrow later used here
diff --git a/src/test/ui/nll/issue-51191.stderr b/src/test/ui/nll/issue-51191.stderr
index 18696f57c44..9f4e971f909 100644
--- a/src/test/ui/nll/issue-51191.stderr
+++ b/src/test/ui/nll/issue-51191.stderr
@@ -45,7 +45,7 @@ error[E0596]: cannot borrow data in a `&` reference as mutable
   --> $DIR/issue-51191.rs:22:9
    |
 LL |         (&mut self).bar();
-   |         ^^^^^^^^^^^ cannot borrow as mutable
+   |         ^^^^^^^^^^^^^^^^^ cannot borrow as mutable
 
 error[E0596]: cannot borrow `self` as mutable, as it is not declared as mutable
   --> $DIR/issue-51191.rs:28:9
diff --git a/src/test/ui/nll/issue-52669.stderr b/src/test/ui/nll/issue-52669.stderr
index db53e444b9e..807b95f7e13 100644
--- a/src/test/ui/nll/issue-52669.stderr
+++ b/src/test/ui/nll/issue-52669.stderr
@@ -7,7 +7,7 @@ LL |     a.b = B;
 LL |     foo(a);
    |         - value moved here
 LL |     a.b.clone()
-   |     ^^^ value borrowed here after move
+   |     ^^^^^^^^^^^ value borrowed here after move
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/nll/issue-53773.stderr b/src/test/ui/nll/issue-53773.stderr
index 45831460e52..11cd423295a 100644
--- a/src/test/ui/nll/issue-53773.stderr
+++ b/src/test/ui/nll/issue-53773.stderr
@@ -7,7 +7,7 @@ LL |
 LL |     }
    |     - here, drop of `child` needs exclusive access to `*child.raw`, because the type `C<'_>` implements the `Drop` trait
 LL |     members.len();
-   |     ------- borrow later used here
+   |     ------------- borrow later used here
    |
    = note: consider using a `let` binding to create a longer lived value
 
diff --git a/src/test/ui/nll/issue-54556-niconii.stderr b/src/test/ui/nll/issue-54556-niconii.stderr
index 70f063ca0e8..a8e1edc5497 100644
--- a/src/test/ui/nll/issue-54556-niconii.stderr
+++ b/src/test/ui/nll/issue-54556-niconii.stderr
@@ -2,7 +2,7 @@ error[E0597]: `counter` does not live long enough
   --> $DIR/issue-54556-niconii.rs:22:20
    |
 LL |     if let Ok(_) = counter.lock() { }
-   |                    ^^^^^^^-------
+   |                    ^^^^^^^^^^^^^^
    |                    |
    |                    borrowed value does not live long enough
    |                    a temporary with access to the borrow is created here ...
diff --git a/src/test/ui/nll/issue-62007-assign-const-index.stderr b/src/test/ui/nll/issue-62007-assign-const-index.stderr
index 0db9fe62c38..12e28aa3fba 100644
--- a/src/test/ui/nll/issue-62007-assign-const-index.stderr
+++ b/src/test/ui/nll/issue-62007-assign-const-index.stderr
@@ -17,7 +17,7 @@ LL | fn to_refs<T>(mut list: [&mut List<T>; 2]) -> Vec<&mut T> {
    |                          - let's call the lifetime of this reference `'1`
 ...
 LL |         if let Some(n) = list[0].next.as_mut() {
-   |                          ^^^^^^^^^^^^---------
+   |                          ^^^^^^^^^^^^^^^^^^^^^
    |                          |
    |                          `list[_].next` was mutably borrowed here in the previous iteration of the loop
    |                          argument requires that `list[_].next` is borrowed for `'1`
diff --git a/src/test/ui/nll/issue-62007-assign-differing-fields.stderr b/src/test/ui/nll/issue-62007-assign-differing-fields.stderr
index f1af2e855af..4488431fc57 100644
--- a/src/test/ui/nll/issue-62007-assign-differing-fields.stderr
+++ b/src/test/ui/nll/issue-62007-assign-differing-fields.stderr
@@ -17,7 +17,7 @@ LL | fn to_refs<'a, T>(mut list: (&'a mut List<T>, &'a mut List<T>)) -> Vec<&'a
    |            -- lifetime `'a` defined here
 ...
 LL |         if let Some(n) = (list.0).next.as_mut() {
-   |                          ^^^^^^^^^^^^^---------
+   |                          ^^^^^^^^^^^^^^^^^^^^^^
    |                          |
    |                          `list.0.next` was mutably borrowed here in the previous iteration of the loop
    |                          argument requires that `list.0.next` is borrowed for `'a`
diff --git a/src/test/ui/nll/loan_ends_mid_block_vec.stderr b/src/test/ui/nll/loan_ends_mid_block_vec.stderr
index c0b97bea348..22c72af61d6 100644
--- a/src/test/ui/nll/loan_ends_mid_block_vec.stderr
+++ b/src/test/ui/nll/loan_ends_mid_block_vec.stderr
@@ -5,7 +5,7 @@ LL |     let slice = &mut data;
    |                 --------- first mutable borrow occurs here
 LL |     capitalize(slice);
 LL |     data.push('d');
-   |     ^^^^ second mutable borrow occurs here
+   |     ^^^^^^^^^^^^^^ second mutable borrow occurs here
 ...
 LL |     capitalize(slice);
    |                ----- first borrow later used here
@@ -17,7 +17,7 @@ LL |     let slice = &mut data;
    |                 --------- first mutable borrow occurs here
 ...
 LL |     data.push('e');
-   |     ^^^^ second mutable borrow occurs here
+   |     ^^^^^^^^^^^^^^ second mutable borrow occurs here
 ...
 LL |     capitalize(slice);
    |                ----- first borrow later used here
@@ -29,7 +29,7 @@ LL |     let slice = &mut data;
    |                 --------- first mutable borrow occurs here
 ...
 LL |     data.push('f');
-   |     ^^^^ second mutable borrow occurs here
+   |     ^^^^^^^^^^^^^^ second mutable borrow occurs here
 LL |
 LL |     capitalize(slice);
    |                ----- first borrow later used here
diff --git a/src/test/ui/nll/polonius/assignment-to-differing-field.stderr b/src/test/ui/nll/polonius/assignment-to-differing-field.stderr
index 2fe6a53a49a..fd5e4531b2e 100644
--- a/src/test/ui/nll/polonius/assignment-to-differing-field.stderr
+++ b/src/test/ui/nll/polonius/assignment-to-differing-field.stderr
@@ -17,7 +17,7 @@ LL | fn assignment_to_field_projection<'a, T>(
    |                                   -- lifetime `'a` defined here
 ...
 LL |         if let Some(n) = (list.0).next.as_mut() {
-   |                          ^^^^^^^^^^^^^---------
+   |                          ^^^^^^^^^^^^^^^^^^^^^^
    |                          |
    |                          `list.0.next` was mutably borrowed here in the previous iteration of the loop
    |                          argument requires that `list.0.next` is borrowed for `'a`
@@ -41,7 +41,7 @@ LL | fn assignment_through_projection_chain<'a, T>(
    |                                        -- lifetime `'a` defined here
 ...
 LL |         if let Some(n) = ((((list.0).0).0).0).0.next.as_mut() {
-   |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^---------
+   |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |                          |
    |                          `list.0.0.0.0.0.next` was mutably borrowed here in the previous iteration of the loop
    |                          argument requires that `list.0.0.0.0.0.next` is borrowed for `'a`
diff --git a/src/test/ui/nll/region-ends-after-if-condition.nll.stderr b/src/test/ui/nll/region-ends-after-if-condition.nll.stderr
deleted file mode 100644
index 322930984a5..00000000000
--- a/src/test/ui/nll/region-ends-after-if-condition.nll.stderr
+++ /dev/null
@@ -1,15 +0,0 @@
-error[E0502]: cannot borrow `my_struct.field` as mutable because it is also borrowed as immutable
-  --> $DIR/region-ends-after-if-condition.rs:26:9
-   |
-LL |     let value = &my_struct.field;
-   |                 ---------------- immutable borrow occurs here
-LL |     if value.is_empty() {
-LL |         my_struct.field.push_str("Hello, world!");
-   |         ^^^^^^^^^^^^^^^ mutable borrow occurs here
-...
-LL |     drop(value);
-   |          ----- immutable borrow later used here
-
-error: aborting due to previous error
-
-For more information about this error, try `rustc --explain E0502`.
diff --git a/src/test/ui/nll/relate_tys/fn-subtype.stderr b/src/test/ui/nll/relate_tys/fn-subtype.stderr
index 94def690086..6256c4a01d3 100644
--- a/src/test/ui/nll/relate_tys/fn-subtype.stderr
+++ b/src/test/ui/nll/relate_tys/fn-subtype.stderr
@@ -4,7 +4,7 @@ error[E0308]: mismatched types
 LL |     let y: for<'a> fn(&'a ()) = x;
    |                                 ^ one type is more general than the other
    |
-   = note: expected fn pointer `for<'r> fn(&'r ())`
+   = note: expected fn pointer `for<'a> fn(&'a ())`
               found fn pointer `fn(&())`
 
 error: aborting due to previous error
diff --git a/src/test/ui/nll/relate_tys/hr-fn-aaa-as-aba.stderr b/src/test/ui/nll/relate_tys/hr-fn-aaa-as-aba.stderr
index 8c1eaeb6aa7..b839015f97f 100644
--- a/src/test/ui/nll/relate_tys/hr-fn-aaa-as-aba.stderr
+++ b/src/test/ui/nll/relate_tys/hr-fn-aaa-as-aba.stderr
@@ -4,7 +4,7 @@ error[E0308]: mismatched types
 LL |     let a: for<'a, 'b> fn(&'a u32, &'b u32) -> &'a u32 = make_it();
    |                                                          ^^^^^^^^^ one type is more general than the other
    |
-   = note: expected fn pointer `for<'r, 's> fn(&'r u32, &'s u32) -> &'r u32`
+   = note: expected fn pointer `for<'a, 'b> fn(&'a u32, &'b u32) -> &'a u32`
               found fn pointer `for<'a> fn(&'a u32, &'a u32) -> &'a u32`
 
 error[E0308]: mismatched types
@@ -14,7 +14,7 @@ LL |     let _: for<'a, 'b> fn(&'a u32, &'b u32) -> &'a u32 = make_it();
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ one type is more general than the other
    |
    = note: expected fn pointer `for<'a, 'b> fn(&'a u32, &'b u32) -> &'a u32`
-              found fn pointer `for<'r> fn(&'r u32, &'r u32) -> &'r u32`
+              found fn pointer `for<'a> fn(&'a u32, &'a u32) -> &'a u32`
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/nll/relate_tys/trait-hrtb.stderr b/src/test/ui/nll/relate_tys/trait-hrtb.stderr
index 60a7f204446..6d144a4be6e 100644
--- a/src/test/ui/nll/relate_tys/trait-hrtb.stderr
+++ b/src/test/ui/nll/relate_tys/trait-hrtb.stderr
@@ -4,7 +4,7 @@ error[E0308]: mismatched types
 LL |     let y: Box<dyn for<'a> Foo<'a>> = x;
    |                                       ^ one type is more general than the other
    |
-   = note: expected trait object `dyn for<'r> Foo<'r>`
+   = note: expected trait object `dyn for<'a> Foo<'a>`
               found trait object `dyn Foo<'_>`
 
 error: aborting due to previous error
diff --git a/src/test/ui/nll/return_from_loop.stderr b/src/test/ui/nll/return_from_loop.stderr
index efd56ea2dd5..bd2b8b15859 100644
--- a/src/test/ui/nll/return_from_loop.stderr
+++ b/src/test/ui/nll/return_from_loop.stderr
@@ -5,10 +5,10 @@ LL |     let value = &mut my_struct.field;
    |                 -------------------- first mutable borrow occurs here
 LL |     loop {
 LL |         my_struct.field.push_str("Hello, world!");
-   |         ^^^^^^^^^^^^^^^ second mutable borrow occurs here
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ second mutable borrow occurs here
 LL |
 LL |         value.len();
-   |         ----- first borrow later used here
+   |         ----------- first borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/object-safety/object-safety-by-value-self-use.stderr b/src/test/ui/object-safety/object-safety-by-value-self-use.stderr
index 1497aa42082..7ccc0cbdd57 100644
--- a/src/test/ui/object-safety/object-safety-by-value-self-use.stderr
+++ b/src/test/ui/object-safety/object-safety-by-value-self-use.stderr
@@ -2,7 +2,7 @@ error[E0161]: cannot move a value of type dyn Bar: the size of dyn Bar cannot be
   --> $DIR/object-safety-by-value-self-use.rs:15:5
    |
 LL |     t.bar()
-   |     ^
+   |     ^^^^^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/pattern/usefulness/const-private-fields.rs b/src/test/ui/pattern/usefulness/const-private-fields.rs
new file mode 100644
index 00000000000..06c832ca46a
--- /dev/null
+++ b/src/test/ui/pattern/usefulness/const-private-fields.rs
@@ -0,0 +1,30 @@
+// check-pass
+//
+// Check that we don't ignore private fields in usefulness checking
+#![deny(unreachable_patterns)]
+
+mod inner {
+    #[derive(PartialEq, Eq)]
+    pub struct PrivateField {
+        pub x: bool,
+        y: bool,
+    }
+
+    pub const FOO: PrivateField = PrivateField { x: true, y: true };
+    pub const BAR: PrivateField = PrivateField { x: true, y: false };
+}
+use inner::*;
+
+fn main() {
+    match FOO {
+        FOO => {}
+        BAR => {}
+        _ => {}
+    }
+
+    match FOO {
+        FOO => {}
+        PrivateField { x: true, .. } => {}
+        _ => {}
+    }
+}
diff --git a/src/test/ui/pattern/usefulness/consts-opaque.stderr b/src/test/ui/pattern/usefulness/consts-opaque.stderr
index 68451043cf5..05c009a6f3f 100644
--- a/src/test/ui/pattern/usefulness/consts-opaque.stderr
+++ b/src/test/ui/pattern/usefulness/consts-opaque.stderr
@@ -7,8 +7,11 @@ LL |         FOO => {}
 error: unreachable pattern
   --> $DIR/consts-opaque.rs:32:9
    |
+LL |         FOO => {}
+   |         --- matches any value
+LL |
 LL |         _ => {} // should not be emitting unreachable warning
-   |         ^
+   |         ^ unreachable pattern
    |
 note: the lint level is defined here
   --> $DIR/consts-opaque.rs:6:9
@@ -25,8 +28,11 @@ LL |         FOO_REF => {}
 error: unreachable pattern
   --> $DIR/consts-opaque.rs:39:9
    |
+LL |         FOO_REF => {}
+   |         ------- matches any value
+LL |
 LL |         Foo(_) => {} // should not be emitting unreachable warning
-   |         ^^^^^^
+   |         ^^^^^^ unreachable pattern
 
 warning: to use a constant of type `Foo` in a pattern, `Foo` must be annotated with `#[derive(PartialEq, Eq)]`
   --> $DIR/consts-opaque.rs:45:9
@@ -70,15 +76,18 @@ LL |         BAR => {}
 error: unreachable pattern
   --> $DIR/consts-opaque.rs:63:9
    |
+LL |         BAR => {}
+   |         --- matches any value
+LL |
 LL |         Bar => {} // should not be emitting unreachable warning
-   |         ^^^
+   |         ^^^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/consts-opaque.rs:65:9
    |
-LL |         Bar => {} // should not be emitting unreachable warning
+LL |         BAR => {}
    |         --- matches any value
-LL |
+...
 LL |         _ => {}
    |         ^ unreachable pattern
 
@@ -97,14 +106,20 @@ LL |         BAR => {} // should not be emitting unreachable warning
 error: unreachable pattern
   --> $DIR/consts-opaque.rs:72:9
    |
+LL |         BAR => {}
+   |         --- matches any value
+LL |
 LL |         BAR => {} // should not be emitting unreachable warning
-   |         ^^^
+   |         ^^^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/consts-opaque.rs:75:9
    |
+LL |         BAR => {}
+   |         --- matches any value
+...
 LL |         _ => {} // should not be emitting unreachable warning
-   |         ^
+   |         ^ unreachable pattern
 
 error: to use a constant of type `Baz` in a pattern, `Baz` must be annotated with `#[derive(PartialEq, Eq)]`
   --> $DIR/consts-opaque.rs:80:9
@@ -115,14 +130,20 @@ LL |         BAZ => {}
 error: unreachable pattern
   --> $DIR/consts-opaque.rs:82:9
    |
+LL |         BAZ => {}
+   |         --- matches any value
+LL |
 LL |         Baz::Baz1 => {} // should not be emitting unreachable warning
-   |         ^^^^^^^^^
+   |         ^^^^^^^^^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/consts-opaque.rs:84:9
    |
+LL |         BAZ => {}
+   |         --- matches any value
+...
 LL |         _ => {}
-   |         ^
+   |         ^ unreachable pattern
 
 error: to use a constant of type `Baz` in a pattern, `Baz` must be annotated with `#[derive(PartialEq, Eq)]`
   --> $DIR/consts-opaque.rs:90:9
@@ -133,8 +154,11 @@ LL |         BAZ => {}
 error: unreachable pattern
   --> $DIR/consts-opaque.rs:92:9
    |
+LL |         BAZ => {}
+   |         --- matches any value
+LL |
 LL |         _ => {}
-   |         ^
+   |         ^ unreachable pattern
 
 error: to use a constant of type `Baz` in a pattern, `Baz` must be annotated with `#[derive(PartialEq, Eq)]`
   --> $DIR/consts-opaque.rs:97:9
@@ -145,20 +169,28 @@ LL |         BAZ => {}
 error: unreachable pattern
   --> $DIR/consts-opaque.rs:99:9
    |
+LL |         BAZ => {}
+   |         --- matches any value
+LL |
 LL |         Baz::Baz2 => {} // should not be emitting unreachable warning
-   |         ^^^^^^^^^
+   |         ^^^^^^^^^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/consts-opaque.rs:101:9
    |
+LL |         BAZ => {}
+   |         --- matches any value
+...
 LL |         _ => {} // should not be emitting unreachable warning
-   |         ^
+   |         ^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/consts-opaque.rs:127:9
    |
+LL |         Wrap(_) => {}
+   |         ------- matches any value
 LL |         WRAPQUUX => {} // detected unreachable because we do inspect the `Wrap` layer
-   |         ^^^^^^^^
+   |         ^^^^^^^^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/consts-opaque.rs:141:9
diff --git a/src/test/ui/pattern/usefulness/integer-ranges/reachability.stderr b/src/test/ui/pattern/usefulness/integer-ranges/reachability.stderr
index 9a02fac6a75..0ffb0ffd82a 100644
--- a/src/test/ui/pattern/usefulness/integer-ranges/reachability.stderr
+++ b/src/test/ui/pattern/usefulness/integer-ranges/reachability.stderr
@@ -133,8 +133,10 @@ LL |         5..15 => {},
 error: unreachable pattern
   --> $DIR/reachability.rs:83:9
    |
+LL |         _ => {},
+   |         - matches any value
 LL |         '\u{D7FF}'..='\u{E000}' => {},
-   |         ^^^^^^^^^^^^^^^^^^^^^^^
+   |         ^^^^^^^^^^^^^^^^^^^^^^^ unreachable pattern
 
 error: unreachable pattern
   --> $DIR/reachability.rs:104:9
diff --git a/src/test/ui/pattern/usefulness/issue-3601.stderr b/src/test/ui/pattern/usefulness/issue-3601.stderr
index c873c20cca8..48ed1491508 100644
--- a/src/test/ui/pattern/usefulness/issue-3601.stderr
+++ b/src/test/ui/pattern/usefulness/issue-3601.stderr
@@ -1,8 +1,8 @@
-error[E0004]: non-exhaustive patterns: `Box(_, _)` not covered
+error[E0004]: non-exhaustive patterns: `box _` not covered
   --> $DIR/issue-3601.rs:30:44
    |
 LL |         box NodeKind::Element(ed) => match ed.kind {
-   |                                            ^^^^^^^ pattern `Box(_, _)` not covered
+   |                                            ^^^^^^^ pattern `box _` not covered
    |
    = help: ensure that all possible cases are being handled, possibly by adding wildcards or more match arms
    = note: the matched value is of type `Box<ElementKind>`
diff --git a/src/test/ui/pattern/usefulness/issue-82772-match-box-as-struct.rs b/src/test/ui/pattern/usefulness/issue-82772-match-box-as-struct.rs
new file mode 100644
index 00000000000..c1bfcc73402
--- /dev/null
+++ b/src/test/ui/pattern/usefulness/issue-82772-match-box-as-struct.rs
@@ -0,0 +1,6 @@
+// This used to ICE in exhaustiveness checking. Explanation here:
+// https://github.com/rust-lang/rust/issues/82772#issuecomment-905946768
+fn main() {
+    let Box { 1: _, .. }: Box<()>; //~ ERROR field `1` of
+    let Box { .. }: Box<()>;
+}
diff --git a/src/test/ui/pattern/usefulness/issue-82772-match-box-as-struct.stderr b/src/test/ui/pattern/usefulness/issue-82772-match-box-as-struct.stderr
new file mode 100644
index 00000000000..2c8c85bb1e0
--- /dev/null
+++ b/src/test/ui/pattern/usefulness/issue-82772-match-box-as-struct.stderr
@@ -0,0 +1,9 @@
+error[E0451]: field `1` of struct `Box` is private
+  --> $DIR/issue-82772-match-box-as-struct.rs:4:15
+   |
+LL |     let Box { 1: _, .. }: Box<()>;
+   |               ^^^^ private field
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0451`.
diff --git a/src/test/ui/recursion/issue-83150.stderr b/src/test/ui/recursion/issue-83150.stderr
index 943d5133097..d45bfc3ca55 100644
--- a/src/test/ui/recursion/issue-83150.stderr
+++ b/src/test/ui/recursion/issue-83150.stderr
@@ -1,6 +1,6 @@
 error[E0275]: overflow evaluating the requirement `Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut std::ops::Range<u8>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>: Iterator`
    |
-   = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`issue_83150`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_83150`)
    = note: required because of the requirements on the impl of `Iterator` for `&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut std::ops::Range<u8>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>, [closure@$DIR/issue-83150.rs:10:24: 10:33]>`
 
 error: aborting due to previous error
diff --git a/src/test/ui/recursion_limit/no-value.rs b/src/test/ui/recursion_limit/no-value.rs
new file mode 100644
index 00000000000..2202e5b7713
--- /dev/null
+++ b/src/test/ui/recursion_limit/no-value.rs
@@ -0,0 +1,6 @@
+// Test the parse error for no value provided to recursion_limit
+
+#![recursion_limit]
+//~^ ERROR malformed `recursion_limit` attribute input
+
+fn main() {}
diff --git a/src/test/ui/recursion_limit/no-value.stderr b/src/test/ui/recursion_limit/no-value.stderr
new file mode 100644
index 00000000000..35ac2c4cd17
--- /dev/null
+++ b/src/test/ui/recursion_limit/no-value.stderr
@@ -0,0 +1,8 @@
+error: malformed `recursion_limit` attribute input
+  --> $DIR/no-value.rs:3:1
+   |
+LL | #![recursion_limit]
+   | ^^^^^^^^^^^^^^^^^^^ help: must be of the form: `#![recursion_limit = "N"]`
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/recursion_limit/zero-overflow.rs b/src/test/ui/recursion_limit/zero-overflow.rs
new file mode 100644
index 00000000000..77bd8185676
--- /dev/null
+++ b/src/test/ui/recursion_limit/zero-overflow.rs
@@ -0,0 +1,7 @@
+//~ ERROR overflow evaluating the requirement `&mut Self: DispatchFromDyn<&mut RustaceansAreAwesome>
+//~| HELP consider increasing the recursion limit
+// build-fail
+
+#![recursion_limit = "0"]
+
+fn main() {}
diff --git a/src/test/ui/recursion_limit/zero-overflow.stderr b/src/test/ui/recursion_limit/zero-overflow.stderr
new file mode 100644
index 00000000000..9007ec0d784
--- /dev/null
+++ b/src/test/ui/recursion_limit/zero-overflow.stderr
@@ -0,0 +1,7 @@
+error[E0275]: overflow evaluating the requirement `&mut Self: DispatchFromDyn<&mut RustaceansAreAwesome>`
+   |
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "2"]` attribute to your crate (`zero_overflow`)
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0275`.
diff --git a/src/test/ui/recursion_limit/zero.stderr b/src/test/ui/recursion_limit/zero.stderr
index 6358805d89d..c85cbadea71 100644
--- a/src/test/ui/recursion_limit/zero.stderr
+++ b/src/test/ui/recursion_limit/zero.stderr
@@ -4,7 +4,7 @@ error: recursion limit reached while expanding `test!`
 LL | test!(test);
    | ^^^^^^^^^^^^
    |
-   = help: consider adding a `#![recursion_limit="0"]` attribute to your crate (`zero`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "2"]` attribute to your crate (`zero`)
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/regions/region-object-lifetime-5.rs b/src/test/ui/regions/region-object-lifetime-5.rs
index 307bbcbd58d..ad359367168 100644
--- a/src/test/ui/regions/region-object-lifetime-5.rs
+++ b/src/test/ui/regions/region-object-lifetime-5.rs
@@ -8,7 +8,7 @@ trait Foo {
 // Here, the object is bounded by an anonymous lifetime and returned
 // as `&'static`, so you get an error.
 fn owned_receiver(x: Box<dyn Foo>) -> &'static () {
-    x.borrowed() //~ ERROR cannot return value referencing local data `*x`
+    x.borrowed() //~ ERROR cannot return reference to local data `*x`
 }
 
 fn main() {}
diff --git a/src/test/ui/regions/region-object-lifetime-5.stderr b/src/test/ui/regions/region-object-lifetime-5.stderr
index b86f6e3a2a1..b82b58c7a8e 100644
--- a/src/test/ui/regions/region-object-lifetime-5.stderr
+++ b/src/test/ui/regions/region-object-lifetime-5.stderr
@@ -1,11 +1,8 @@
-error[E0515]: cannot return value referencing local data `*x`
+error[E0515]: cannot return reference to local data `*x`
   --> $DIR/region-object-lifetime-5.rs:11:5
    |
 LL |     x.borrowed()
-   |     -^^^^^^^^^^^
-   |     |
-   |     returns a value referencing data owned by the current function
-   |     `*x` is borrowed here
+   |     ^^^^^^^^^^^^ returns a reference to data owned by the current function
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/resolve/issue-42944.stderr b/src/test/ui/resolve/issue-42944.stderr
index 008492529d1..cad3ccc4a0e 100644
--- a/src/test/ui/resolve/issue-42944.stderr
+++ b/src/test/ui/resolve/issue-42944.stderr
@@ -16,10 +16,11 @@ error[E0425]: cannot find function, tuple struct or tuple variant `Bx` in this s
 LL |         Bx(());
    |         ^^ not found in this scope
    |
-help: consider importing this tuple struct
-   |
-LL |     use foo::Bx;
+note: tuple struct `foo::Bx` exists but is inaccessible
+  --> $DIR/issue-42944.rs:2:5
    |
+LL |     pub struct Bx(());
+   |     ^^^^^^^^^^^^^^^^^^ not accessible
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/resolve/issue-88472.rs b/src/test/ui/resolve/issue-88472.rs
new file mode 100644
index 00000000000..6bf7caeddbf
--- /dev/null
+++ b/src/test/ui/resolve/issue-88472.rs
@@ -0,0 +1,38 @@
+// Regression test for #88472, where a suggestion was issued to
+// import an inaccessible struct.
+
+#![warn(unused_imports)]
+//~^ NOTE: the lint level is defined here
+
+mod a {
+    struct Foo;
+    //~^ NOTE: struct `a::Foo` exists but is inaccessible
+    //~| NOTE: not accessible
+}
+
+mod b {
+    use crate::a::*;
+    //~^ WARNING: unused import
+    type Bar = Foo;
+    //~^ ERROR: cannot find type `Foo` in this scope [E0412]
+    //~| NOTE: not found in this scope
+}
+
+mod c {
+    enum Eee {}
+    //~^ NOTE: these enums exist but are inaccessible
+    //~| NOTE: `c::Eee`: not accessible
+
+    mod d {
+        enum Eee {}
+        //~^ NOTE: `c::d::Eee`: not accessible
+    }
+}
+
+mod e {
+    type Baz = Eee;
+    //~^ ERROR: cannot find type `Eee` in this scope [E0412]
+    //~| NOTE: not found in this scope
+}
+
+fn main() {}
diff --git a/src/test/ui/resolve/issue-88472.stderr b/src/test/ui/resolve/issue-88472.stderr
new file mode 100644
index 00000000000..8431fc97766
--- /dev/null
+++ b/src/test/ui/resolve/issue-88472.stderr
@@ -0,0 +1,42 @@
+error[E0412]: cannot find type `Foo` in this scope
+  --> $DIR/issue-88472.rs:16:16
+   |
+LL |     type Bar = Foo;
+   |                ^^^ not found in this scope
+   |
+note: struct `a::Foo` exists but is inaccessible
+  --> $DIR/issue-88472.rs:8:5
+   |
+LL |     struct Foo;
+   |     ^^^^^^^^^^^ not accessible
+
+error[E0412]: cannot find type `Eee` in this scope
+  --> $DIR/issue-88472.rs:33:16
+   |
+LL |     type Baz = Eee;
+   |                ^^^ not found in this scope
+   |
+note: these enums exist but are inaccessible
+  --> $DIR/issue-88472.rs:22:5
+   |
+LL |     enum Eee {}
+   |     ^^^^^^^^ `c::Eee`: not accessible
+...
+LL |         enum Eee {}
+   |         ^^^^^^^^ `c::d::Eee`: not accessible
+
+warning: unused import: `crate::a::*`
+  --> $DIR/issue-88472.rs:14:9
+   |
+LL |     use crate::a::*;
+   |         ^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/issue-88472.rs:4:9
+   |
+LL | #![warn(unused_imports)]
+   |         ^^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0412`.
diff --git a/src/test/ui/resolve/privacy-enum-ctor.stderr b/src/test/ui/resolve/privacy-enum-ctor.stderr
index 192349e0faf..ff72b0b563a 100644
--- a/src/test/ui/resolve/privacy-enum-ctor.stderr
+++ b/src/test/ui/resolve/privacy-enum-ctor.stderr
@@ -169,16 +169,13 @@ LL |     pub enum E {
    |     ---------- similarly named enum `E` defined here
 ...
 LL |     let _: Z = m::n::Z;
-   |            ^
+   |            ^ help: an enum with a similar name exists: `E`
    |
-help: an enum with a similar name exists
-   |
-LL |     let _: E = m::n::Z;
-   |            ~
-help: consider importing this enum
-   |
-LL | use m::Z;
+note: enum `m::Z` exists but is inaccessible
+  --> $DIR/privacy-enum-ctor.rs:11:9
    |
+LL |         pub(in m) enum Z {
+   |         ^^^^^^^^^^^^^^^^ not accessible
 
 error[E0423]: expected value, found enum `m::n::Z`
   --> $DIR/privacy-enum-ctor.rs:57:16
@@ -215,16 +212,13 @@ LL |     pub enum E {
    |     ---------- similarly named enum `E` defined here
 ...
 LL |     let _: Z = m::n::Z::Fn;
-   |            ^
+   |            ^ help: an enum with a similar name exists: `E`
    |
-help: an enum with a similar name exists
-   |
-LL |     let _: E = m::n::Z::Fn;
-   |            ~
-help: consider importing this enum
-   |
-LL | use m::Z;
+note: enum `m::Z` exists but is inaccessible
+  --> $DIR/privacy-enum-ctor.rs:11:9
    |
+LL |         pub(in m) enum Z {
+   |         ^^^^^^^^^^^^^^^^ not accessible
 
 error[E0412]: cannot find type `Z` in this scope
   --> $DIR/privacy-enum-ctor.rs:64:12
@@ -233,16 +227,13 @@ LL |     pub enum E {
    |     ---------- similarly named enum `E` defined here
 ...
 LL |     let _: Z = m::n::Z::Struct;
-   |            ^
+   |            ^ help: an enum with a similar name exists: `E`
    |
-help: an enum with a similar name exists
-   |
-LL |     let _: E = m::n::Z::Struct;
-   |            ~
-help: consider importing this enum
-   |
-LL | use m::Z;
+note: enum `m::Z` exists but is inaccessible
+  --> $DIR/privacy-enum-ctor.rs:11:9
    |
+LL |         pub(in m) enum Z {
+   |         ^^^^^^^^^^^^^^^^ not accessible
 
 error[E0423]: expected value, found struct variant `m::n::Z::Struct`
   --> $DIR/privacy-enum-ctor.rs:64:16
@@ -262,16 +253,13 @@ LL |     pub enum E {
    |     ---------- similarly named enum `E` defined here
 ...
 LL |     let _: Z = m::n::Z::Unit {};
-   |            ^
+   |            ^ help: an enum with a similar name exists: `E`
    |
-help: an enum with a similar name exists
-   |
-LL |     let _: E = m::n::Z::Unit {};
-   |            ~
-help: consider importing this enum
-   |
-LL | use m::Z;
+note: enum `m::Z` exists but is inaccessible
+  --> $DIR/privacy-enum-ctor.rs:11:9
    |
+LL |         pub(in m) enum Z {
+   |         ^^^^^^^^^^^^^^^^ not accessible
 
 error[E0603]: enum `Z` is private
   --> $DIR/privacy-enum-ctor.rs:57:22
diff --git a/src/test/ui/resolve/privacy-struct-ctor.stderr b/src/test/ui/resolve/privacy-struct-ctor.stderr
index e5d6f7e9e24..ada053014ef 100644
--- a/src/test/ui/resolve/privacy-struct-ctor.stderr
+++ b/src/test/ui/resolve/privacy-struct-ctor.stderr
@@ -33,10 +33,11 @@ error[E0423]: expected value, found struct `xcrate::S`
 LL |     xcrate::S;
    |     ^^^^^^^^^ constructor is not visible here due to private fields
    |
-help: consider importing this tuple struct instead
-   |
-LL | use m::S;
+note: tuple struct `m::S` exists but is inaccessible
+  --> $DIR/privacy-struct-ctor.rs:6:5
    |
+LL |     pub struct S(u8);
+   |     ^^^^^^^^^^^^^^^^^ not accessible
 
 error[E0603]: tuple struct constructor `Z` is private
   --> $DIR/privacy-struct-ctor.rs:18:12
diff --git a/src/test/ui/rfc-2005-default-binding-mode/borrowck-issue-49631.nll.stderr b/src/test/ui/rfc-2005-default-binding-mode/borrowck-issue-49631.nll.stderr
deleted file mode 100644
index c74b82dbbd8..00000000000
--- a/src/test/ui/rfc-2005-default-binding-mode/borrowck-issue-49631.nll.stderr
+++ /dev/null
@@ -1,14 +0,0 @@
-error[E0502]: cannot borrow `foo` as mutable because it is also borrowed as immutable
-  --> $DIR/borrowck-issue-49631.rs:20:9
-   |
-LL |     while let Some(Ok(string)) = foo.get() {
-   |                                  --- immutable borrow occurs here
-LL |         foo.mutate();
-   |         ^^^ mutable borrow occurs here
-LL |
-LL |         println!("foo={:?}", *string);
-   |                              ------- immutable borrow later used here
-
-error: aborting due to previous error
-
-For more information about this error, try `rustc --explain E0502`.
diff --git a/src/test/ui/rfc-2005-default-binding-mode/borrowck-issue-49631.stderr b/src/test/ui/rfc-2005-default-binding-mode/borrowck-issue-49631.stderr
index 04572920ee4..b7c0b0bb6b9 100644
--- a/src/test/ui/rfc-2005-default-binding-mode/borrowck-issue-49631.stderr
+++ b/src/test/ui/rfc-2005-default-binding-mode/borrowck-issue-49631.stderr
@@ -2,7 +2,7 @@ error[E0502]: cannot borrow `foo` as mutable because it is also borrowed as immu
   --> $DIR/borrowck-issue-49631.rs:20:9
    |
 LL |     while let Some(Ok(string)) = foo.get() {
-   |                                  --- immutable borrow occurs here
+   |                                  --------- immutable borrow occurs here
 LL |         foo.mutate();
    |         ^^^^^^^^^^^^ mutable borrow occurs here
 LL |
diff --git a/src/test/ui/rfc1623.nll.stderr b/src/test/ui/rfc1623.nll.stderr
index cc247bbcb11..7f15c1c1f57 100644
--- a/src/test/ui/rfc1623.nll.stderr
+++ b/src/test/ui/rfc1623.nll.stderr
@@ -31,7 +31,7 @@ LL | |
 LL | | };
    | |_^ one type is more general than the other
    |
-   = note: expected type `for<'r, 's> Fn<(&'r Foo<'s>,)>`
+   = note: expected type `for<'a, 'b> Fn<(&'a Foo<'b>,)>`
               found type `Fn<(&Foo<'_>,)>`
 
 error[E0308]: mismatched types
@@ -46,7 +46,7 @@ LL | |
 LL | | };
    | |_^ one type is more general than the other
    |
-   = note: expected type `for<'r, 's> Fn<(&'r Foo<'s>,)>`
+   = note: expected type `for<'a, 'b> Fn<(&'a Foo<'b>,)>`
               found type `Fn<(&Foo<'_>,)>`
 
 error: implementation of `FnOnce` is not general enough
@@ -61,7 +61,7 @@ LL | |
 LL | | };
    | |_^ implementation of `FnOnce` is not general enough
    |
-   = note: `fn(&'2 Foo<'_>) -> &'2 Foo<'_> {id::<&'2 Foo<'_>>}` must implement `FnOnce<(&'1 Foo<'_>,)>`, for any lifetime `'1`...
+   = note: `fn(&'2 Foo<'_>) -> &'2 Foo<'_> {id::<&'2 Foo<'_>>}` must implement `FnOnce<(&'1 Foo<'b>,)>`, for any lifetime `'1`...
    = note: ...but it actually implements `FnOnce<(&'2 Foo<'_>,)>`, for some specific lifetime `'2`
 
 error: implementation of `FnOnce` is not general enough
@@ -76,7 +76,7 @@ LL | |
 LL | | };
    | |_^ implementation of `FnOnce` is not general enough
    |
-   = note: `fn(&Foo<'2>) -> &Foo<'2> {id::<&Foo<'2>>}` must implement `FnOnce<(&Foo<'1>,)>`, for any lifetime `'1`...
+   = note: `fn(&Foo<'2>) -> &Foo<'2> {id::<&Foo<'2>>}` must implement `FnOnce<(&'a Foo<'1>,)>`, for any lifetime `'1`...
    = note: ...but it actually implements `FnOnce<(&Foo<'2>,)>`, for some specific lifetime `'2`
 
 error: aborting due to 5 previous errors
diff --git a/src/test/ui/self/self_type_keyword.stderr b/src/test/ui/self/self_type_keyword.stderr
index 47c04f1eb72..aca08d81163 100644
--- a/src/test/ui/self/self_type_keyword.stderr
+++ b/src/test/ui/self/self_type_keyword.stderr
@@ -66,10 +66,11 @@ error[E0531]: cannot find unit struct, unit variant or constant `Self` in this s
 LL |         mut Self => (),
    |             ^^^^ not found in this scope
    |
-help: consider importing this unit struct
-   |
-LL | use foo::Self;
+note: unit struct `foo::Self` exists but is inaccessible
+  --> $DIR/self_type_keyword.rs:2:3
    |
+LL |   struct Self;
+   |   ^^^^^^^^^^^^ not accessible
 
 error[E0392]: parameter `'Self` is never used
   --> $DIR/self_type_keyword.rs:6:12
diff --git a/src/test/ui/span/borrowck-borrow-overloaded-auto-deref-mut.stderr b/src/test/ui/span/borrowck-borrow-overloaded-auto-deref-mut.stderr
index 8fceef64c8c..e4ec9f87576 100644
--- a/src/test/ui/span/borrowck-borrow-overloaded-auto-deref-mut.stderr
+++ b/src/test/ui/span/borrowck-borrow-overloaded-auto-deref-mut.stderr
@@ -56,7 +56,7 @@ error[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable
 LL | fn deref_mut_method1(x: Own<Point>) {
    |                      - help: consider changing this to be mutable: `mut x`
 LL |     x.set(0, 0);
-   |     ^ cannot borrow as mutable
+   |     ^^^^^^^^^^^ cannot borrow as mutable
 
 error[E0596]: cannot borrow `*x` as mutable, as it is behind a `&` reference
   --> $DIR/borrowck-borrow-overloaded-auto-deref-mut.rs:121:5
@@ -64,7 +64,7 @@ error[E0596]: cannot borrow `*x` as mutable, as it is behind a `&` reference
 LL | fn deref_extend_mut_method1(x: &Own<Point>) -> &mut isize {
    |                                ----------- help: consider changing this to be a mutable reference: `&mut Own<Point>`
 LL |     x.y_mut()
-   |     ^ `x` is a `&` reference, so the data it refers to cannot be borrowed as mutable
+   |     ^^^^^^^^^ `x` is a `&` reference, so the data it refers to cannot be borrowed as mutable
 
 error[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable
   --> $DIR/borrowck-borrow-overloaded-auto-deref-mut.rs:129:6
@@ -72,7 +72,7 @@ error[E0596]: cannot borrow `x` as mutable, as it is not declared as mutable
 LL | fn assign_method1<'a>(x: Own<Point>) {
    |                       - help: consider changing this to be mutable: `mut x`
 LL |     *x.y_mut() = 3;
-   |      ^ cannot borrow as mutable
+   |      ^^^^^^^^^ cannot borrow as mutable
 
 error[E0596]: cannot borrow `*x` as mutable, as it is behind a `&` reference
   --> $DIR/borrowck-borrow-overloaded-auto-deref-mut.rs:133:6
@@ -80,7 +80,7 @@ error[E0596]: cannot borrow `*x` as mutable, as it is behind a `&` reference
 LL | fn assign_method2<'a>(x: &'a Own<Point>) {
    |                          -------------- help: consider changing this to be a mutable reference: `&'a mut Own<Point>`
 LL |     *x.y_mut() = 3;
-   |      ^ `x` is a `&` reference, so the data it refers to cannot be borrowed as mutable
+   |      ^^^^^^^^^ `x` is a `&` reference, so the data it refers to cannot be borrowed as mutable
 
 error: aborting due to 10 previous errors
 
diff --git a/src/test/ui/span/borrowck-call-is-borrow-issue-12224.stderr b/src/test/ui/span/borrowck-call-is-borrow-issue-12224.stderr
index 0f630abd148..b4693b7242a 100644
--- a/src/test/ui/span/borrowck-call-is-borrow-issue-12224.stderr
+++ b/src/test/ui/span/borrowck-call-is-borrow-issue-12224.stderr
@@ -24,7 +24,7 @@ error[E0596]: cannot borrow `f.f` as mutable, as it is behind a `&` reference
 LL | fn test4(f: &Test) {
    |             ----- help: consider changing this to be a mutable reference: `&mut Test<'_>`
 LL |     f.f.call_mut(())
-   |     ^^^ `f` is a `&` reference, so the data it refers to cannot be borrowed as mutable
+   |     ^^^^^^^^^^^^^^^^ `f` is a `&` reference, so the data it refers to cannot be borrowed as mutable
 
 error[E0507]: cannot move out of `f`, a captured variable in an `FnMut` closure
   --> $DIR/borrowck-call-is-borrow-issue-12224.rs:57:13
diff --git a/src/test/ui/span/borrowck-call-method-from-mut-aliasable.stderr b/src/test/ui/span/borrowck-call-method-from-mut-aliasable.stderr
index 6b5e0779e5f..1864f5de108 100644
--- a/src/test/ui/span/borrowck-call-method-from-mut-aliasable.stderr
+++ b/src/test/ui/span/borrowck-call-method-from-mut-aliasable.stderr
@@ -5,7 +5,7 @@ LL | fn b(x: &Foo) {
    |         ---- help: consider changing this to be a mutable reference: `&mut Foo`
 LL |     x.f();
 LL |     x.h();
-   |     ^ `x` is a `&` reference, so the data it refers to cannot be borrowed as mutable
+   |     ^^^^^ `x` is a `&` reference, so the data it refers to cannot be borrowed as mutable
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/span/borrowck-fn-in-const-b.stderr b/src/test/ui/span/borrowck-fn-in-const-b.stderr
index 8949a10481a..1f5d8bd32bb 100644
--- a/src/test/ui/span/borrowck-fn-in-const-b.stderr
+++ b/src/test/ui/span/borrowck-fn-in-const-b.stderr
@@ -4,7 +4,7 @@ error[E0596]: cannot borrow `*x` as mutable, as it is behind a `&` reference
 LL |     fn broken(x: &Vec<String>) {
    |                  ------------ help: consider changing this to be a mutable reference: `&mut Vec<String>`
 LL |         x.push(format!("this is broken"));
-   |         ^ `x` is a `&` reference, so the data it refers to cannot be borrowed as mutable
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `x` is a `&` reference, so the data it refers to cannot be borrowed as mutable
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/span/borrowck-let-suggestion-suffixes.stderr b/src/test/ui/span/borrowck-let-suggestion-suffixes.stderr
index 7ba909d208a..7c5caba6eae 100644
--- a/src/test/ui/span/borrowck-let-suggestion-suffixes.stderr
+++ b/src/test/ui/span/borrowck-let-suggestion-suffixes.stderr
@@ -32,7 +32,7 @@ LL |         v4.push(&id('y'));
    |                  creates a temporary which is freed while still in use
 ...
 LL |         v4.use_ref();
-   |         -- borrow later used here
+   |         ------------ borrow later used here
    |
    = note: consider using a `let` binding to create a longer lived value
 
diff --git a/src/test/ui/span/borrowck-object-mutability.stderr b/src/test/ui/span/borrowck-object-mutability.stderr
index fe6d05c588f..cc43f6d0928 100644
--- a/src/test/ui/span/borrowck-object-mutability.stderr
+++ b/src/test/ui/span/borrowck-object-mutability.stderr
@@ -5,7 +5,7 @@ LL | fn borrowed_receiver(x: &dyn Foo) {
    |                         -------- help: consider changing this to be a mutable reference: `&mut dyn Foo`
 LL |     x.borrowed();
 LL |     x.borrowed_mut();
-   |     ^ `x` is a `&` reference, so the data it refers to cannot be borrowed as mutable
+   |     ^^^^^^^^^^^^^^^^ `x` is a `&` reference, so the data it refers to cannot be borrowed as mutable
 
 error[E0596]: cannot borrow `*x` as mutable, as `x` is not declared as mutable
   --> $DIR/borrowck-object-mutability.rs:18:5
@@ -14,7 +14,7 @@ LL | fn owned_receiver(x: Box<dyn Foo>) {
    |                   - help: consider changing this to be mutable: `mut x`
 LL |     x.borrowed();
 LL |     x.borrowed_mut();
-   |     ^ cannot borrow as mutable
+   |     ^^^^^^^^^^^^^^^^ cannot borrow as mutable
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/span/destructor-restrictions.stderr b/src/test/ui/span/destructor-restrictions.stderr
index 8f75c388f65..53c9404620f 100644
--- a/src/test/ui/span/destructor-restrictions.stderr
+++ b/src/test/ui/span/destructor-restrictions.stderr
@@ -2,7 +2,7 @@ error[E0597]: `*a` does not live long enough
   --> $DIR/destructor-restrictions.rs:8:10
    |
 LL |         *a.borrow() + 1
-   |          ^---------
+   |          ^^^^^^^^^^
    |          |
    |          borrowed value does not live long enough
    |          a temporary with access to the borrow is created here ...
diff --git a/src/test/ui/span/issue-23338-locals-die-before-temps-of-body.stderr b/src/test/ui/span/issue-23338-locals-die-before-temps-of-body.stderr
index 8d4709d660f..3c2022748f0 100644
--- a/src/test/ui/span/issue-23338-locals-die-before-temps-of-body.stderr
+++ b/src/test/ui/span/issue-23338-locals-die-before-temps-of-body.stderr
@@ -2,7 +2,7 @@ error[E0597]: `y` does not live long enough
   --> $DIR/issue-23338-locals-die-before-temps-of-body.rs:10:5
    |
 LL |     y.borrow().clone()
-   |     ^---------
+   |     ^^^^^^^^^^
    |     |
    |     borrowed value does not live long enough
    |     a temporary with access to the borrow is created here ...
@@ -23,7 +23,7 @@ error[E0597]: `y` does not live long enough
   --> $DIR/issue-23338-locals-die-before-temps-of-body.rs:17:9
    |
 LL |         y.borrow().clone()
-   |         ^---------
+   |         ^^^^^^^^^^
    |         |
    |         borrowed value does not live long enough
    |         a temporary with access to the borrow is created here ...
diff --git a/src/test/ui/span/issue-36537.stderr b/src/test/ui/span/issue-36537.stderr
index 0939584380a..79a0ebaeb8d 100644
--- a/src/test/ui/span/issue-36537.stderr
+++ b/src/test/ui/span/issue-36537.stderr
@@ -7,7 +7,7 @@ LL |         p = &a;
 LL |     }
    |     - `a` dropped here while still borrowed
 LL |     p.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/span/issue-40157.stderr b/src/test/ui/span/issue-40157.stderr
index 0b365c3f7b6..57f80214a4f 100644
--- a/src/test/ui/span/issue-40157.stderr
+++ b/src/test/ui/span/issue-40157.stderr
@@ -2,7 +2,7 @@ error[E0597]: `foo` does not live long enough
   --> $DIR/issue-40157.rs:2:53
    |
 LL |     {println!("{:?}", match { let foo = vec![1, 2]; foo.get(1) } { x => x });}
-   |                             ------------------------^^^---------
+   |                             ------------------------^^^^^^^^^^--
    |                             |                       |          |
    |                             |                       |          `foo` dropped here while still borrowed
    |                             |                       borrowed value does not live long enough
diff --git a/src/test/ui/span/issue-7575.stderr b/src/test/ui/span/issue-7575.stderr
index 288c1042a26..783f5aca417 100644
--- a/src/test/ui/span/issue-7575.stderr
+++ b/src/test/ui/span/issue-7575.stderr
@@ -27,16 +27,16 @@ LL |     fn f9(_: usize) -> usize;
            candidate #3: `UnusedTrait`
 help: disambiguate the associated function for candidate #1
    |
-LL |     u.f8(42) + CtxtFn::f9(u, 342) + m.fff(42)
-   |                ~~~~~~~~~~~~~~~~~~
+LL |     u.f8(42) + <usize as CtxtFn>::f9(u, 342) + m.fff(42)
+   |                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 help: disambiguate the associated function for candidate #2
    |
-LL |     u.f8(42) + OtherTrait::f9(u, 342) + m.fff(42)
-   |                ~~~~~~~~~~~~~~~~~~~~~~
+LL |     u.f8(42) + <usize as OtherTrait>::f9(u, 342) + m.fff(42)
+   |                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 help: disambiguate the associated function for candidate #3
    |
-LL |     u.f8(42) + UnusedTrait::f9(u, 342) + m.fff(42)
-   |                ~~~~~~~~~~~~~~~~~~~~~~~
+LL |     u.f8(42) + <usize as UnusedTrait>::f9(u, 342) + m.fff(42)
+   |                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 error[E0599]: no method named `fff` found for struct `Myisize` in the current scope
   --> $DIR/issue-7575.rs:62:30
@@ -72,7 +72,7 @@ LL |     fn is_str() -> bool {
    = help: items from traits can only be used if the type parameter is bounded by the trait
 help: disambiguate the associated function for the candidate
    |
-LL |     ManyImplTrait::is_str(t)
+LL |     <T as ManyImplTrait>::is_str(t)
    |
 
 error: aborting due to 3 previous errors
diff --git a/src/test/ui/span/mut-arg-hint.stderr b/src/test/ui/span/mut-arg-hint.stderr
index e04e4cbdabb..8a7c504f005 100644
--- a/src/test/ui/span/mut-arg-hint.stderr
+++ b/src/test/ui/span/mut-arg-hint.stderr
@@ -4,7 +4,7 @@ error[E0596]: cannot borrow `*a` as mutable, as it is behind a `&` reference
 LL |     fn foo(mut a: &String) {
    |                   ------- help: consider changing this to be a mutable reference: `&mut String`
 LL |         a.push_str("bar");
-   |         ^ `a` is a `&` reference, so the data it refers to cannot be borrowed as mutable
+   |         ^^^^^^^^^^^^^^^^^ `a` is a `&` reference, so the data it refers to cannot be borrowed as mutable
 
 error[E0596]: cannot borrow `*a` as mutable, as it is behind a `&` reference
   --> $DIR/mut-arg-hint.rs:8:5
@@ -12,7 +12,7 @@ error[E0596]: cannot borrow `*a` as mutable, as it is behind a `&` reference
 LL | pub fn foo<'a>(mut a: &'a String) {
    |                       ---------- help: consider changing this to be a mutable reference: `&'a mut String`
 LL |     a.push_str("foo");
-   |     ^ `a` is a `&` reference, so the data it refers to cannot be borrowed as mutable
+   |     ^^^^^^^^^^^^^^^^^ `a` is a `&` reference, so the data it refers to cannot be borrowed as mutable
 
 error[E0596]: cannot borrow `*a` as mutable, as it is behind a `&` reference
   --> $DIR/mut-arg-hint.rs:15:9
@@ -20,7 +20,7 @@ error[E0596]: cannot borrow `*a` as mutable, as it is behind a `&` reference
 LL |     pub fn foo(mut a: &String) {
    |                       ------- help: consider changing this to be a mutable reference: `&mut String`
 LL |         a.push_str("foo");
-   |         ^ `a` is a `&` reference, so the data it refers to cannot be borrowed as mutable
+   |         ^^^^^^^^^^^^^^^^^ `a` is a `&` reference, so the data it refers to cannot be borrowed as mutable
 
 error: aborting due to 3 previous errors
 
diff --git a/src/test/ui/span/mut-ptr-cant-outlive-ref.stderr b/src/test/ui/span/mut-ptr-cant-outlive-ref.stderr
index 21b29464df5..4d976a7bbfa 100644
--- a/src/test/ui/span/mut-ptr-cant-outlive-ref.stderr
+++ b/src/test/ui/span/mut-ptr-cant-outlive-ref.stderr
@@ -7,7 +7,7 @@ LL |     }
    |     - `b` dropped here while still borrowed
 LL |
 LL |     p.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/span/regionck-unboxed-closure-lifetimes.stderr b/src/test/ui/span/regionck-unboxed-closure-lifetimes.stderr
index 8e9cd595154..0b985de609c 100644
--- a/src/test/ui/span/regionck-unboxed-closure-lifetimes.stderr
+++ b/src/test/ui/span/regionck-unboxed-closure-lifetimes.stderr
@@ -7,7 +7,7 @@ LL |         let c_ref = &c;
 LL |     }
    |     - `c` dropped here while still borrowed
 LL |     f.use_mut();
-   |     - borrow later used here
+   |     ----------- borrow later used here
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/span/regions-escape-loop-via-vec.stderr b/src/test/ui/span/regions-escape-loop-via-vec.stderr
index b47250db723..2b649307739 100644
--- a/src/test/ui/span/regions-escape-loop-via-vec.stderr
+++ b/src/test/ui/span/regions-escape-loop-via-vec.stderr
@@ -7,7 +7,7 @@ LL |     while x < 10 {
    |           ^ use of borrowed `x`
 LL |         let mut z = x;
 LL |         _y.push(&mut z);
-   |         -- borrow later used here
+   |         --------------- borrow later used here
 
 error[E0503]: cannot use `x` because it was mutably borrowed
   --> $DIR/regions-escape-loop-via-vec.rs:6:21
@@ -18,14 +18,15 @@ LL |     while x < 10 {
 LL |         let mut z = x;
    |                     ^ use of borrowed `x`
 LL |         _y.push(&mut z);
-   |         -- borrow later used here
+   |         --------------- borrow later used here
 
 error[E0597]: `z` does not live long enough
   --> $DIR/regions-escape-loop-via-vec.rs:7:17
    |
 LL |         _y.push(&mut z);
-   |         --      ^^^^^^ borrowed value does not live long enough
-   |         |
+   |         --------^^^^^^-
+   |         |       |
+   |         |       borrowed value does not live long enough
    |         borrow later used here
 ...
 LL |     }
@@ -38,7 +39,7 @@ LL |     let mut _y = vec![&mut x];
    |                       ------ borrow of `x` occurs here
 ...
 LL |         _y.push(&mut z);
-   |         -- borrow later used here
+   |         --------------- borrow later used here
 LL |
 LL |         x += 1;
    |         ^^^^^^ use of borrowed `x`
diff --git a/src/test/ui/span/send-is-not-static-std-sync.stderr b/src/test/ui/span/send-is-not-static-std-sync.stderr
index 81de8c29906..5d493a3e4ee 100644
--- a/src/test/ui/span/send-is-not-static-std-sync.stderr
+++ b/src/test/ui/span/send-is-not-static-std-sync.stderr
@@ -7,7 +7,7 @@ LL |     drop(y);
    |          ^ move out of `y` occurs here
 ...
 LL |         *lock.lock().unwrap() = &z;
-   |          ---- borrow later used here
+   |          ----------- borrow later used here
 
 error[E0597]: `z` does not live long enough
   --> $DIR/send-is-not-static-std-sync.rs:16:33
@@ -18,7 +18,7 @@ LL |     }
    |     - `z` dropped here while still borrowed
 LL |
 LL |     lock.use_ref(); // (Mutex is #[may_dangle] so its dtor does not use `z` => needs explicit use)
-   |     ---- borrow later used here
+   |     -------------- borrow later used here
 
 error[E0505]: cannot move out of `y` because it is borrowed
   --> $DIR/send-is-not-static-std-sync.rs:27:10
@@ -29,7 +29,7 @@ LL |     drop(y);
    |          ^ move out of `y` occurs here
 ...
 LL |         *lock.write().unwrap() = &z;
-   |          ---- borrow later used here
+   |          ------------ borrow later used here
 
 error[E0597]: `z` does not live long enough
   --> $DIR/send-is-not-static-std-sync.rs:30:34
@@ -40,7 +40,7 @@ LL |     }
    |     - `z` dropped here while still borrowed
 LL |
 LL |     lock.use_ref(); // (RwLock is #[may_dangle] so its dtor does not use `z` => needs explicit use)
-   |     ---- borrow later used here
+   |     -------------- borrow later used here
 
 error[E0505]: cannot move out of `y` because it is borrowed
   --> $DIR/send-is-not-static-std-sync.rs:43:10
@@ -51,7 +51,7 @@ LL |     drop(y);
    |          ^ move out of `y` occurs here
 ...
 LL |         tx.send(&z).unwrap();
-   |         -- borrow later used here
+   |         ----------- borrow later used here
 
 error[E0597]: `z` does not live long enough
   --> $DIR/send-is-not-static-std-sync.rs:46:17
diff --git a/src/test/ui/span/slice-borrow.stderr b/src/test/ui/span/slice-borrow.stderr
index 62a4a6009d4..27df25be3fa 100644
--- a/src/test/ui/span/slice-borrow.stderr
+++ b/src/test/ui/span/slice-borrow.stderr
@@ -7,7 +7,7 @@ LL |         let x: &[isize] = &vec![1, 2, 3, 4, 5];
 LL |     }
    |     - temporary value is freed at the end of this statement
 LL |     y.use_ref();
-   |     - borrow later used here
+   |     ----------- borrow later used here
    |
    = note: consider using a `let` binding to create a longer lived value
    = note: this error originates in the macro `vec` (in Nightly builds, run with -Z macro-backtrace for more info)
diff --git a/src/test/ui/suggestions/core-std-import-order-issue-83564.rs b/src/test/ui/suggestions/core-std-import-order-issue-83564.rs
new file mode 100644
index 00000000000..b7fe5af7bf8
--- /dev/null
+++ b/src/test/ui/suggestions/core-std-import-order-issue-83564.rs
@@ -0,0 +1,10 @@
+// edition:2018
+
+// This is a regression test for #83564.
+// For some reason, Rust 2018 or higher is required to reproduce the bug.
+
+fn main() {
+    //~^ HELP consider importing one of these items
+    let _x = NonZeroU32::new(5).unwrap();
+    //~^ ERROR failed to resolve: use of undeclared type `NonZeroU32`
+}
diff --git a/src/test/ui/suggestions/core-std-import-order-issue-83564.stderr b/src/test/ui/suggestions/core-std-import-order-issue-83564.stderr
new file mode 100644
index 00000000000..d484fb8cbe0
--- /dev/null
+++ b/src/test/ui/suggestions/core-std-import-order-issue-83564.stderr
@@ -0,0 +1,16 @@
+error[E0433]: failed to resolve: use of undeclared type `NonZeroU32`
+  --> $DIR/core-std-import-order-issue-83564.rs:8:14
+   |
+LL |     let _x = NonZeroU32::new(5).unwrap();
+   |              ^^^^^^^^^^ not found in this scope
+   |
+help: consider importing one of these items
+   |
+LL | use std::num::NonZeroU32;
+   |
+LL | use core::num::NonZeroU32;
+   |
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0433`.
diff --git a/src/test/ui/suggestions/impl-on-dyn-trait-with-implicit-static-bound-needing-more-suggestions.nll.stderr b/src/test/ui/suggestions/impl-on-dyn-trait-with-implicit-static-bound-needing-more-suggestions.nll.stderr
index 043a771129a..80d3c940eb7 100644
--- a/src/test/ui/suggestions/impl-on-dyn-trait-with-implicit-static-bound-needing-more-suggestions.nll.stderr
+++ b/src/test/ui/suggestions/impl-on-dyn-trait-with-implicit-static-bound-needing-more-suggestions.nll.stderr
@@ -4,7 +4,7 @@ error[E0597]: `val` does not live long enough
 LL |     fn use_it<'a>(val: Box<dyn ObjectTrait<Assoc = i32>>) -> impl OtherTrait<'a> {
    |               -- lifetime `'a` defined here                  ------------------- opaque type requires that `val` is borrowed for `'a`
 LL |         val.use_self()
-   |         ^^^ borrowed value does not live long enough
+   |         ^^^^^^^^^^^^^^ borrowed value does not live long enough
 LL |     }
    |     - `val` dropped here while still borrowed
    |
@@ -13,23 +13,17 @@ help: you can add a bound to the opaque type to make it last less than `'static`
 LL |     fn use_it<'a>(val: Box<dyn ObjectTrait<Assoc = i32>>) -> impl OtherTrait<'a> + 'a {
    |                                                                                  ++++
 
-error[E0515]: cannot return value referencing function parameter `val`
+error[E0515]: cannot return reference to function parameter `val`
   --> $DIR/impl-on-dyn-trait-with-implicit-static-bound-needing-more-suggestions.rs:43:9
    |
 LL |         val.use_self()
-   |         ---^^^^^^^^^^^
-   |         |
-   |         returns a value referencing data owned by the current function
-   |         `val` is borrowed here
+   |         ^^^^^^^^^^^^^^ returns a reference to data owned by the current function
 
-error[E0515]: cannot return value referencing function parameter `val`
+error[E0515]: cannot return reference to function parameter `val`
   --> $DIR/impl-on-dyn-trait-with-implicit-static-bound-needing-more-suggestions.rs:109:9
    |
 LL |         val.use_self()
-   |         ---^^^^^^^^^^^
-   |         |
-   |         returns a value referencing data owned by the current function
-   |         `val` is borrowed here
+   |         ^^^^^^^^^^^^^^ returns a reference to data owned by the current function
 
 error: aborting due to 3 previous errors
 
diff --git a/src/test/ui/suggestions/impl-on-dyn-trait-with-implicit-static-bound-needing-more-suggestions.stderr b/src/test/ui/suggestions/impl-on-dyn-trait-with-implicit-static-bound-needing-more-suggestions.stderr
index 29991b6572f..e8c3a7908f5 100644
--- a/src/test/ui/suggestions/impl-on-dyn-trait-with-implicit-static-bound-needing-more-suggestions.stderr
+++ b/src/test/ui/suggestions/impl-on-dyn-trait-with-implicit-static-bound-needing-more-suggestions.stderr
@@ -4,7 +4,7 @@ error[E0597]: `val` does not live long enough
 LL |     fn use_it<'a>(val: Box<dyn ObjectTrait<Assoc = i32>>) -> impl OtherTrait<'a> {
    |               -- lifetime `'a` defined here                  ------------------- opaque type requires that `val` is borrowed for `'a`
 LL |         val.use_self()
-   |         ^^^ borrowed value does not live long enough
+   |         ^^^^^^^^^^^^^^ borrowed value does not live long enough
 LL |     }
    |     - `val` dropped here while still borrowed
    |
@@ -13,23 +13,17 @@ help: you can add a bound to the opaque type to make it last less than `'static`
 LL |     fn use_it<'a>(val: Box<dyn ObjectTrait<Assoc = i32>>) -> impl OtherTrait<'a> + 'a {
    |                                                                                  ++++
 
-error[E0515]: cannot return value referencing function parameter `val`
+error[E0515]: cannot return reference to function parameter `val`
   --> $DIR/impl-on-dyn-trait-with-implicit-static-bound-needing-more-suggestions.rs:43:9
    |
 LL |         val.use_self()
-   |         ---^^^^^^^^^^^
-   |         |
-   |         returns a value referencing data owned by the current function
-   |         `val` is borrowed here
+   |         ^^^^^^^^^^^^^^ returns a reference to data owned by the current function
 
-error[E0515]: cannot return value referencing function parameter `val`
+error[E0515]: cannot return reference to function parameter `val`
   --> $DIR/impl-on-dyn-trait-with-implicit-static-bound-needing-more-suggestions.rs:109:9
    |
 LL |         val.use_self()
-   |         ---^^^^^^^^^^^
-   |         |
-   |         returns a value referencing data owned by the current function
-   |         `val` is borrowed here
+   |         ^^^^^^^^^^^^^^ returns a reference to data owned by the current function
 
 error[E0772]: `val` has lifetime `'a` but calling `use_self` introduces an implicit `'static` lifetime requirement
   --> $DIR/impl-on-dyn-trait-with-implicit-static-bound-needing-more-suggestions.rs:66:13
diff --git a/src/test/ui/suggestions/issue-88730.rs b/src/test/ui/suggestions/issue-88730.rs
new file mode 100644
index 00000000000..e63210a3e98
--- /dev/null
+++ b/src/test/ui/suggestions/issue-88730.rs
@@ -0,0 +1,16 @@
+#![allow(unused, nonstandard_style)]
+#![deny(bindings_with_variant_name)]
+
+// If an enum has two different variants,
+// then it cannot be matched upon in a function argument.
+// It still gets a warning, but no suggestions.
+enum Foo {
+    C,
+    D,
+}
+
+fn foo(C: Foo) {} //~ERROR
+
+fn main() {
+    let C = Foo::D; //~ERROR
+}
diff --git a/src/test/ui/suggestions/issue-88730.stderr b/src/test/ui/suggestions/issue-88730.stderr
new file mode 100644
index 00000000000..eb22b0ea5c8
--- /dev/null
+++ b/src/test/ui/suggestions/issue-88730.stderr
@@ -0,0 +1,21 @@
+error[E0170]: pattern binding `C` is named the same as one of the variants of the type `Foo`
+  --> $DIR/issue-88730.rs:12:8
+   |
+LL | fn foo(C: Foo) {}
+   |        ^
+   |
+note: the lint level is defined here
+  --> $DIR/issue-88730.rs:2:9
+   |
+LL | #![deny(bindings_with_variant_name)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0170]: pattern binding `C` is named the same as one of the variants of the type `Foo`
+  --> $DIR/issue-88730.rs:15:9
+   |
+LL |     let C = Foo::D;
+   |         ^
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0170`.
diff --git a/src/test/ui/suggestions/negative-literal-index.fixed b/src/test/ui/suggestions/negative-literal-index.fixed
new file mode 100644
index 00000000000..e52714cf97f
--- /dev/null
+++ b/src/test/ui/suggestions/negative-literal-index.fixed
@@ -0,0 +1,22 @@
+// run-rustfix
+
+use std::ops::Index;
+struct X;
+impl Index<i32> for X {
+    type Output = ();
+
+    fn index(&self, _: i32) -> &() {
+        &()
+    }
+}
+
+fn main() {
+    let x = vec![1, 2, 3];
+    x[x.len() -1]; //~ ERROR negative integers cannot be used to index on a
+    let x = [1, 2, 3];
+    x[x.len() -1]; //~ ERROR negative integers cannot be used to index on a
+    let x = &[1, 2, 3];
+    x[x.len() -1]; //~ ERROR negative integers cannot be used to index on a
+    let _ = x;
+    X[-1];
+}
diff --git a/src/test/ui/suggestions/negative-literal-index.rs b/src/test/ui/suggestions/negative-literal-index.rs
new file mode 100644
index 00000000000..d88b66e679e
--- /dev/null
+++ b/src/test/ui/suggestions/negative-literal-index.rs
@@ -0,0 +1,22 @@
+// run-rustfix
+
+use std::ops::Index;
+struct X;
+impl Index<i32> for X {
+    type Output = ();
+
+    fn index(&self, _: i32) -> &() {
+        &()
+    }
+}
+
+fn main() {
+    let x = vec![1, 2, 3];
+    x[-1]; //~ ERROR negative integers cannot be used to index on a
+    let x = [1, 2, 3];
+    x[-1]; //~ ERROR negative integers cannot be used to index on a
+    let x = &[1, 2, 3];
+    x[-1]; //~ ERROR negative integers cannot be used to index on a
+    let _ = x;
+    X[-1];
+}
diff --git a/src/test/ui/suggestions/negative-literal-index.stderr b/src/test/ui/suggestions/negative-literal-index.stderr
new file mode 100644
index 00000000000..2b51bf7b7ce
--- /dev/null
+++ b/src/test/ui/suggestions/negative-literal-index.stderr
@@ -0,0 +1,35 @@
+error: negative integers cannot be used to index on a `Vec<{integer}>`
+  --> $DIR/negative-literal-index.rs:15:7
+   |
+LL |     x[-1];
+   |       ^^ cannot use a negative integer for indexing on `Vec<{integer}>`
+   |
+help: to access an element starting from the end of the `Vec<{integer}>`, compute the index
+   |
+LL |     x[x.len() -1];
+   |       +++++++
+
+error: negative integers cannot be used to index on a `[{integer}; 3]`
+  --> $DIR/negative-literal-index.rs:17:7
+   |
+LL |     x[-1];
+   |       ^^ cannot use a negative integer for indexing on `[{integer}; 3]`
+   |
+help: to access an element starting from the end of the `[{integer}; 3]`, compute the index
+   |
+LL |     x[x.len() -1];
+   |       +++++++
+
+error: negative integers cannot be used to index on a `[{integer}; 3]`
+  --> $DIR/negative-literal-index.rs:19:7
+   |
+LL |     x[-1];
+   |       ^^ cannot use a negative integer for indexing on `[{integer}; 3]`
+   |
+help: to access an element starting from the end of the `[{integer}; 3]`, compute the index
+   |
+LL |     x[x.len() -1];
+   |       +++++++
+
+error: aborting due to 3 previous errors
+
diff --git a/src/test/ui/suggestions/suggest-trait-items.rs b/src/test/ui/suggestions/suggest-trait-items.rs
new file mode 100644
index 00000000000..9d42a734260
--- /dev/null
+++ b/src/test/ui/suggestions/suggest-trait-items.rs
@@ -0,0 +1,48 @@
+trait Foo {
+    type Type;
+
+    fn foo();
+    fn bar();
+    fn qux();
+}
+
+struct A;
+
+impl Foo for A {
+//~^ ERROR not all trait items implemented
+    type Typ = ();
+    //~^ ERROR type `Typ` is not a member of trait
+    //~| HELP there is an associated type with a similar name
+
+    fn fooo() {}
+    //~^ ERROR method `fooo` is not a member of trait
+    //~| HELP there is an associated function with a similar name
+
+    fn barr() {}
+    //~^ ERROR method `barr` is not a member of trait
+    //~| HELP there is an associated function with a similar name
+
+    fn quux() {}
+    //~^ ERROR method `quux` is not a member of trait
+    //~| HELP there is an associated function with a similar name
+}
+//~^ HELP implement the missing item
+//~| HELP implement the missing item
+//~| HELP implement the missing item
+//~| HELP implement the missing item
+
+trait Bar {
+    const Const: i32;
+}
+
+struct B;
+
+impl Bar for B {
+//~^ ERROR not all trait items implemented
+    const Cnst: i32 = 0;
+    //~^ ERROR const `Cnst` is not a member of trait
+    //~| HELP there is an associated constant with a similar name
+}
+//~^ HELP implement the missing item
+
+fn main() {}
diff --git a/src/test/ui/suggestions/suggest-trait-items.stderr b/src/test/ui/suggestions/suggest-trait-items.stderr
new file mode 100644
index 00000000000..151bae7d1b9
--- /dev/null
+++ b/src/test/ui/suggestions/suggest-trait-items.stderr
@@ -0,0 +1,74 @@
+error[E0437]: type `Typ` is not a member of trait `Foo`
+  --> $DIR/suggest-trait-items.rs:13:5
+   |
+LL |     type Typ = ();
+   |     ^^^^^---^^^^^^
+   |     |    |
+   |     |    help: there is an associated type with a similar name: `Type`
+   |     not a member of trait `Foo`
+
+error[E0407]: method `fooo` is not a member of trait `Foo`
+  --> $DIR/suggest-trait-items.rs:17:5
+   |
+LL |     fn fooo() {}
+   |     ^^^----^^^^^
+   |     |  |
+   |     |  help: there is an associated function with a similar name: `foo`
+   |     not a member of trait `Foo`
+
+error[E0407]: method `barr` is not a member of trait `Foo`
+  --> $DIR/suggest-trait-items.rs:21:5
+   |
+LL |     fn barr() {}
+   |     ^^^----^^^^^
+   |     |  |
+   |     |  help: there is an associated function with a similar name: `bar`
+   |     not a member of trait `Foo`
+
+error[E0407]: method `quux` is not a member of trait `Foo`
+  --> $DIR/suggest-trait-items.rs:25:5
+   |
+LL |     fn quux() {}
+   |     ^^^----^^^^^
+   |     |  |
+   |     |  help: there is an associated function with a similar name: `qux`
+   |     not a member of trait `Foo`
+
+error[E0438]: const `Cnst` is not a member of trait `Bar`
+  --> $DIR/suggest-trait-items.rs:42:5
+   |
+LL |     const Cnst: i32 = 0;
+   |     ^^^^^^----^^^^^^^^^^
+   |     |     |
+   |     |     help: there is an associated constant with a similar name: `Const`
+   |     not a member of trait `Bar`
+
+error[E0046]: not all trait items implemented, missing: `Type`, `foo`, `bar`, `qux`
+  --> $DIR/suggest-trait-items.rs:11:1
+   |
+LL |     type Type;
+   |     ---------- `Type` from trait
+LL | 
+LL |     fn foo();
+   |     --------- `foo` from trait
+LL |     fn bar();
+   |     --------- `bar` from trait
+LL |     fn qux();
+   |     --------- `qux` from trait
+...
+LL | impl Foo for A {
+   | ^^^^^^^^^^^^^^ missing `Type`, `foo`, `bar`, `qux` in implementation
+
+error[E0046]: not all trait items implemented, missing: `Const`
+  --> $DIR/suggest-trait-items.rs:40:1
+   |
+LL |     const Const: i32;
+   |     ----------------- `Const` from trait
+...
+LL | impl Bar for B {
+   | ^^^^^^^^^^^^^^ missing `Const` in implementation
+
+error: aborting due to 7 previous errors
+
+Some errors have detailed explanations: E0046, E0407, E0437, E0438.
+For more information about an error, try `rustc --explain E0046`.
diff --git a/src/test/ui/traits/auxiliary/issue_89119_intercrate_caching.rs b/src/test/ui/traits/auxiliary/issue_89119_intercrate_caching.rs
new file mode 100644
index 00000000000..769e8973163
--- /dev/null
+++ b/src/test/ui/traits/auxiliary/issue_89119_intercrate_caching.rs
@@ -0,0 +1,60 @@
+// This is the auxiliary crate for the regression test for issue #89119, minimized
+// from `zvariant-2.8.0`.
+
+use std::convert::TryFrom;
+use std::borrow::Cow;
+
+pub struct Str<'a>(Cow<'a, str>);
+impl<'a> Str<'a> {
+    pub fn to_owned(&self) -> Str<'static> {
+        todo!()
+    }
+}
+
+pub enum Value<'a> {
+    Str(Str<'a>),
+    Value(Box<Value<'a>>),
+}
+impl<'a> Value<'a> {
+    pub fn to_owned(&self) -> Value<'static> {
+        match self {
+            Value::Str(v) => Value::Str(v.to_owned()),
+            Value::Value(v) => {
+                let o = OwnedValue::from(&**v);
+                Value::Value(Box::new(o.into_inner()))
+            }
+        }
+    }
+}
+
+struct OwnedValue(Value<'static>);
+impl OwnedValue {
+    pub(crate) fn into_inner(self) -> Value<'static> {
+        todo!()
+    }
+}
+impl<'a, T> TryFrom<OwnedValue> for Vec<T>
+where
+    T: TryFrom<Value<'a>, Error = ()>,
+{
+    type Error = ();
+    fn try_from(_: OwnedValue) -> Result<Self, Self::Error> {
+        todo!()
+    }
+}
+impl TryFrom<OwnedValue> for Vec<OwnedValue> {
+    type Error = ();
+    fn try_from(_: OwnedValue) -> Result<Self, Self::Error> {
+        todo!()
+    }
+}
+impl<'a> From<Value<'a>> for OwnedValue {
+    fn from(_: Value<'a>) -> Self {
+        todo!()
+    }
+}
+impl<'a> From<&Value<'a>> for OwnedValue {
+    fn from(_: &Value<'a>) -> Self {
+        todo!()
+    }
+}
diff --git a/src/test/ui/traits/issue-89119.rs b/src/test/ui/traits/issue-89119.rs
new file mode 100644
index 00000000000..170f69915e2
--- /dev/null
+++ b/src/test/ui/traits/issue-89119.rs
@@ -0,0 +1,11 @@
+// This is a regression test for issue #89119: an issue in intercrate mode caching.
+//
+// It requires multiple crates, of course, but the bug is triggered by the code in the dependency,
+// not the main crate. This is why this file is empty.
+//
+// The auxiliary crate used in the test contains the code minimized from `zvariant-2.8.0`.
+
+// check-pass
+// aux-build: issue_89119_intercrate_caching.rs
+
+fn main() {}
diff --git a/src/test/ui/traits/mutual-recursion-issue-75860.stderr b/src/test/ui/traits/mutual-recursion-issue-75860.stderr
index d2ac3a836f6..920f66121e0 100644
--- a/src/test/ui/traits/mutual-recursion-issue-75860.stderr
+++ b/src/test/ui/traits/mutual-recursion-issue-75860.stderr
@@ -4,7 +4,7 @@ error[E0275]: overflow evaluating the requirement `Option<_>: Sized`
 LL |     iso(left, right)
    |     ^^^
    |
-   = help: consider adding a `#![recursion_limit="256"]` attribute to your crate (`mutual_recursion_issue_75860`)
+   = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`mutual_recursion_issue_75860`)
 note: required by a bound in `Option`
   --> $SRC_DIR/core/src/option.rs:LL:COL
    |
diff --git a/src/test/ui/typeck/call-block.rs b/src/test/ui/typeck/call-block.rs
new file mode 100644
index 00000000000..0390d7db040
--- /dev/null
+++ b/src/test/ui/typeck/call-block.rs
@@ -0,0 +1,3 @@
+fn main() {
+    let _ = {42}(); //~ ERROR expected function, found `{integer}`
+}
diff --git a/src/test/ui/typeck/call-block.stderr b/src/test/ui/typeck/call-block.stderr
new file mode 100644
index 00000000000..68984bc1c45
--- /dev/null
+++ b/src/test/ui/typeck/call-block.stderr
@@ -0,0 +1,11 @@
+error[E0618]: expected function, found `{integer}`
+  --> $DIR/call-block.rs:2:13
+   |
+LL |     let _ = {42}();
+   |             ^^^^--
+   |             |
+   |             call expression requires function
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0618`.
diff --git a/src/test/ui/unop-move-semantics.stderr b/src/test/ui/unop-move-semantics.stderr
index 95a0f4f5fab..199d5e37278 100644
--- a/src/test/ui/unop-move-semantics.stderr
+++ b/src/test/ui/unop-move-semantics.stderr
@@ -7,7 +7,7 @@ LL |     !x;
    |     -- `x` moved due to usage in operator
 LL | 
 LL |     x.clone();
-   |     ^ value borrowed here after move
+   |     ^^^^^^^^^ value borrowed here after move
    |
 note: calling this operator moves the left-hand side
   --> $SRC_DIR/core/src/ops/bit.rs:LL:COL
diff --git a/src/test/ui/use/use-after-move-implicity-coerced-object.stderr b/src/test/ui/use/use-after-move-implicity-coerced-object.stderr
index 539ea94a70d..0ad6d6c7c0e 100644
--- a/src/test/ui/use/use-after-move-implicity-coerced-object.stderr
+++ b/src/test/ui/use/use-after-move-implicity-coerced-object.stderr
@@ -8,7 +8,7 @@ LL |     l.push(n);
    |            - value moved here
 LL | 
 LL |     let x = n.to_string();
-   |             ^ value borrowed here after move
+   |             ^^^^^^^^^^^^^ value borrowed here after move
 
 error: aborting due to previous error
 
diff --git a/src/tools/cargo b/src/tools/cargo
-Subproject 0121d66aa2ef5ffa9735f86c2b56f5fdc5a837a
+Subproject d56b42c549dbb7e7d0f712c51b39400260d114d
diff --git a/src/tools/clippy/.cargo/config b/src/tools/clippy/.cargo/config
index 84ae36a46d7..688473f2f9b 100644
--- a/src/tools/clippy/.cargo/config
+++ b/src/tools/clippy/.cargo/config
@@ -1,9 +1,10 @@
 [alias]
 uitest = "test --test compile-test"
-dev = "run --target-dir clippy_dev/target --package clippy_dev --bin clippy_dev --manifest-path clippy_dev/Cargo.toml --"
-lintcheck = "run --target-dir lintcheck/target --package lintcheck --bin lintcheck --manifest-path lintcheck/Cargo.toml  -- "
+dev = "run --package clippy_dev --bin clippy_dev --manifest-path clippy_dev/Cargo.toml --"
+lintcheck = "run --package lintcheck --bin lintcheck --manifest-path lintcheck/Cargo.toml  -- "
 collect-metadata = "test --test dogfood --features metadata-collector-lint -- run_metadata_collection_lint --ignored"
 
 [build]
 # -Zbinary-dep-depinfo allows us to track which rlib files to use for compiling UI tests
 rustflags = ["-Zunstable-options", "-Zbinary-dep-depinfo"]
+target-dir = "target"
diff --git a/src/tools/clippy/.github/ISSUE_TEMPLATE/blank_issue.md b/src/tools/clippy/.github/ISSUE_TEMPLATE/blank_issue.md
index 2891d5e5da1..866303a1f9f 100644
--- a/src/tools/clippy/.github/ISSUE_TEMPLATE/blank_issue.md
+++ b/src/tools/clippy/.github/ISSUE_TEMPLATE/blank_issue.md
@@ -8,7 +8,7 @@ about: Create a blank issue.
 Additional labels can be added to this issue by including the following command
 (without the space after the @ symbol):
 
-`@rustbot label +<label>`
+@ rustbot label +<label>
 
 Common labels for this issue type are:
 * C-an-interesting-project
diff --git a/src/tools/clippy/.github/ISSUE_TEMPLATE/bug_report.md b/src/tools/clippy/.github/ISSUE_TEMPLATE/bug_report.md
index 87c18cdee66..119a498fb99 100644
--- a/src/tools/clippy/.github/ISSUE_TEMPLATE/bug_report.md
+++ b/src/tools/clippy/.github/ISSUE_TEMPLATE/bug_report.md
@@ -36,7 +36,7 @@ LLVM version: 10.0
 Additional labels can be added to this issue by including the following command
 (without the space after the @ symbol):
 
-`@rustbot label +<label>`
+@ rustbot label +<label>
 
 Common labels for this issue type are:
 * `I-suggestion-causes-error`
diff --git a/src/tools/clippy/.github/ISSUE_TEMPLATE/false_positive.md b/src/tools/clippy/.github/ISSUE_TEMPLATE/false_positive.md
index 4170b9ff2db..82158e02f08 100644
--- a/src/tools/clippy/.github/ISSUE_TEMPLATE/false_positive.md
+++ b/src/tools/clippy/.github/ISSUE_TEMPLATE/false_positive.md
@@ -37,7 +37,7 @@ LLVM version: 10.0
 Additional labels can be added to this issue by including the following command
 (without the space after the @ symbol):
 
-`@rustbot label +<label>`
+@ rustbot label +<label>
 
 Common labels for this issue type are:
 * I-suggestion-causes-error
diff --git a/src/tools/clippy/CHANGELOG.md b/src/tools/clippy/CHANGELOG.md
index f5ac2f7c9f8..58ea0f9ab9d 100644
--- a/src/tools/clippy/CHANGELOG.md
+++ b/src/tools/clippy/CHANGELOG.md
@@ -6,11 +6,81 @@ document.
 
 ## Unreleased / In Rust Nightly
 
-[74d1561...master](https://github.com/rust-lang/rust-clippy/compare/74d1561...master)
+[7bfc26e...master](https://github.com/rust-lang/rust-clippy/compare/7bfc26e...master)
+
+## Rust 1.56
+
+Current beta, release 2021-10-21
+
+[74d1561...7bfc26e](https://github.com/rust-lang/rust-clippy/compare/74d1561...7bfc26e)
+
+### New Lints
+
+* [`unwrap_or_else_default`]
+  [#7516](https://github.com/rust-lang/rust-clippy/pull/7516)
+
+### Enhancements
+
+* [`needless_continue`]: Now also lints in `loop { continue; }` case
+  [#7477](https://github.com/rust-lang/rust-clippy/pull/7477)
+* [`disallowed_type`]: Now also primitive types can be disallowed
+  [#7488](https://github.com/rust-lang/rust-clippy/pull/7488)
+* [`manual_swap`]: Now also lints on xor swaps
+  [#7506](https://github.com/rust-lang/rust-clippy/pull/7506)
+* [`map_flatten`]: Now also lints on the `Result` type
+  [#7522](https://github.com/rust-lang/rust-clippy/pull/7522)
+* [`no_effect`]: Now also lints on inclusive ranges
+  [#7556](https://github.com/rust-lang/rust-clippy/pull/7556)
+
+### False Positive Fixes
+
+* [`nonstandard_macro_braces`]: No longer lints on similar named nested macros
+  [#7478](https://github.com/rust-lang/rust-clippy/pull/7478)
+* [`too_many_lines`]: No longer lints in closures to avoid duplicated diagnostics
+  [#7534](https://github.com/rust-lang/rust-clippy/pull/7534)
+* [`similar_names`]: No longer complains about `iter` and `item` being too
+  similar [#7546](https://github.com/rust-lang/rust-clippy/pull/7546)
+
+### Suggestion Fixes/Improvements
+
+* [`similar_names`]: No longer suggests to insert or add an underscore as a fix
+  [#7221](https://github.com/rust-lang/rust-clippy/pull/7221)
+* [`new_without_default`]: No longer shows the full qualified type path when
+  suggesting adding a `Default` implementation
+  [#7493](https://github.com/rust-lang/rust-clippy/pull/7493)
+* [`while_let_on_iterator`]: Now suggests re-borrowing mutable references
+  [#7520](https://github.com/rust-lang/rust-clippy/pull/7520)
+* [`extend_with_drain`]: Improve code suggestion for mutable and immutable
+  references [#7533](https://github.com/rust-lang/rust-clippy/pull/7533)
+* [`trivially_copy_pass_by_ref`]: Now properly handles `Self` type
+  [#7535](https://github.com/rust-lang/rust-clippy/pull/7535)
+* [`never_loop`]: Now suggests using `if let` instead of a `for` loop when
+  applicable [#7541](https://github.com/rust-lang/rust-clippy/pull/7541)
+
+### Documentation Improvements
+
+* Clippy now uses a lint to generate its lint documentation. [Lints all the way
+  down](https://en.wikipedia.org/wiki/Turtles_all_the_way_down).
+  [#7502](https://github.com/rust-lang/rust-clippy/pull/7502)
+* Reworked Clippy's website:
+  [#7172](https://github.com/rust-lang/rust-clippy/issues/7172)
+  [#7279](https://github.com/rust-lang/rust-clippy/pull/7279)
+  * Added applicability information about lints
+  * Added a link to jump into the implementation
+  * Improved loading times
+  * Adapted some styling
+* `cargo clippy --help` now also explains the `--fix` and `--no-deps` flag
+  [#7492](https://github.com/rust-lang/rust-clippy/pull/7492)
+* [`unnested_or_patterns`]: Removed `or_patterns` feature gate in the code
+  example [#7507](https://github.com/rust-lang/rust-clippy/pull/7507)
+
+### New Lints
+
+* Renamed Lint: `if_let_some_result` is now called [`match_result_ok`]. Now also handles `while let` case.
 
 ## Rust 1.55
 
-Current beta, release 2021-09-09
+Current stable, released 2021-09-09
 
 [3ae8faf...74d1561](https://github.com/rust-lang/rust-clippy/compare/3ae8faf...74d1561)
 
@@ -126,21 +196,9 @@ Current beta, release 2021-09-09
 * [`use_self`]
   [#7428](https://github.com/rust-lang/rust-clippy/pull/7428)
 
-### Documentation Improvements
-
-* Reworked Clippy's website:
-  [#7279](https://github.com/rust-lang/rust-clippy/pull/7279)
-  [#7172](https://github.com/rust-lang/rust-clippy/issues/7172)
-  * Added applicability information about lints
-  * Added a link to jump into the implementation
-  * Improved loading times
-  * Adapted some styling
-* Clippy now uses a lint to generate its documentation
-  [#7298](https://github.com/rust-lang/rust-clippy/pull/7298)
-
 ## Rust 1.54
 
-Current stable, released 2021-07-29
+Released 2021-07-29
 
 [7c7683c...3ae8faf](https://github.com/rust-lang/rust-clippy/compare/7c7683c...3ae8faf)
 
@@ -1050,7 +1108,7 @@ Released 2020-11-19
   [#5913](https://github.com/rust-lang/rust-clippy/pull/5913)
 * Add example of false positive to [`ptr_arg`] docs.
   [#5885](https://github.com/rust-lang/rust-clippy/pull/5885)
-* [`box_vec`], [`vec_box`] and [`borrowed_box`]: add link to the documentation of `Box`
+* [`box_vec`](https://rust-lang.github.io/rust-clippy/master/index.html#box_collection), [`vec_box`] and [`borrowed_box`]: add link to the documentation of `Box`
   [#6023](https://github.com/rust-lang/rust-clippy/pull/6023)
 
 ## Rust 1.47
@@ -1491,7 +1549,7 @@ Released 2020-03-12
 * `unknown_clippy_lints` [#4963](https://github.com/rust-lang/rust-clippy/pull/4963)
 * [`explicit_into_iter_loop`] [#4978](https://github.com/rust-lang/rust-clippy/pull/4978)
 * [`useless_attribute`] [#5022](https://github.com/rust-lang/rust-clippy/pull/5022)
-* [`if_let_some_result`] [#5032](https://github.com/rust-lang/rust-clippy/pull/5032)
+* `if_let_some_result` [#5032](https://github.com/rust-lang/rust-clippy/pull/5032)
 
 ### ICE fixes
 
@@ -2570,7 +2628,7 @@ Released 2018-09-13
 [`bool_comparison`]: https://rust-lang.github.io/rust-clippy/master/index.html#bool_comparison
 [`borrow_interior_mutable_const`]: https://rust-lang.github.io/rust-clippy/master/index.html#borrow_interior_mutable_const
 [`borrowed_box`]: https://rust-lang.github.io/rust-clippy/master/index.html#borrowed_box
-[`box_vec`]: https://rust-lang.github.io/rust-clippy/master/index.html#box_vec
+[`box_collection`]: https://rust-lang.github.io/rust-clippy/master/index.html#box_collection
 [`boxed_local`]: https://rust-lang.github.io/rust-clippy/master/index.html#boxed_local
 [`branches_sharing_code`]: https://rust-lang.github.io/rust-clippy/master/index.html#branches_sharing_code
 [`builtin_type_shadow`]: https://rust-lang.github.io/rust-clippy/master/index.html#builtin_type_shadow
@@ -2685,9 +2743,9 @@ Released 2018-09-13
 [`identity_op`]: https://rust-lang.github.io/rust-clippy/master/index.html#identity_op
 [`if_let_mutex`]: https://rust-lang.github.io/rust-clippy/master/index.html#if_let_mutex
 [`if_let_redundant_pattern_matching`]: https://rust-lang.github.io/rust-clippy/master/index.html#if_let_redundant_pattern_matching
-[`if_let_some_result`]: https://rust-lang.github.io/rust-clippy/master/index.html#if_let_some_result
 [`if_not_else`]: https://rust-lang.github.io/rust-clippy/master/index.html#if_not_else
 [`if_same_then_else`]: https://rust-lang.github.io/rust-clippy/master/index.html#if_same_then_else
+[`if_then_panic`]: https://rust-lang.github.io/rust-clippy/master/index.html#if_then_panic
 [`if_then_some_else_none`]: https://rust-lang.github.io/rust-clippy/master/index.html#if_then_some_else_none
 [`ifs_same_cond`]: https://rust-lang.github.io/rust-clippy/master/index.html#ifs_same_cond
 [`implicit_clone`]: https://rust-lang.github.io/rust-clippy/master/index.html#implicit_clone
@@ -2722,6 +2780,7 @@ Released 2018-09-13
 [`iter_count`]: https://rust-lang.github.io/rust-clippy/master/index.html#iter_count
 [`iter_next_loop`]: https://rust-lang.github.io/rust-clippy/master/index.html#iter_next_loop
 [`iter_next_slice`]: https://rust-lang.github.io/rust-clippy/master/index.html#iter_next_slice
+[`iter_not_returning_iterator`]: https://rust-lang.github.io/rust-clippy/master/index.html#iter_not_returning_iterator
 [`iter_nth`]: https://rust-lang.github.io/rust-clippy/master/index.html#iter_nth
 [`iter_nth_zero`]: https://rust-lang.github.io/rust-clippy/master/index.html#iter_nth_zero
 [`iter_skip_next`]: https://rust-lang.github.io/rust-clippy/master/index.html#iter_skip_next
@@ -2773,6 +2832,7 @@ Released 2018-09-13
 [`match_on_vec_items`]: https://rust-lang.github.io/rust-clippy/master/index.html#match_on_vec_items
 [`match_overlapping_arm`]: https://rust-lang.github.io/rust-clippy/master/index.html#match_overlapping_arm
 [`match_ref_pats`]: https://rust-lang.github.io/rust-clippy/master/index.html#match_ref_pats
+[`match_result_ok`]: https://rust-lang.github.io/rust-clippy/master/index.html#match_result_ok
 [`match_same_arms`]: https://rust-lang.github.io/rust-clippy/master/index.html#match_same_arms
 [`match_single_binding`]: https://rust-lang.github.io/rust-clippy/master/index.html#match_single_binding
 [`match_wild_err_arm`]: https://rust-lang.github.io/rust-clippy/master/index.html#match_wild_err_arm
@@ -2905,6 +2965,7 @@ Released 2018-09-13
 [`reversed_empty_ranges`]: https://rust-lang.github.io/rust-clippy/master/index.html#reversed_empty_ranges
 [`same_functions_in_if_condition`]: https://rust-lang.github.io/rust-clippy/master/index.html#same_functions_in_if_condition
 [`same_item_push`]: https://rust-lang.github.io/rust-clippy/master/index.html#same_item_push
+[`same_name_method`]: https://rust-lang.github.io/rust-clippy/master/index.html#same_name_method
 [`search_is_some`]: https://rust-lang.github.io/rust-clippy/master/index.html#search_is_some
 [`self_assignment`]: https://rust-lang.github.io/rust-clippy/master/index.html#self_assignment
 [`self_named_constructors`]: https://rust-lang.github.io/rust-clippy/master/index.html#self_named_constructors
diff --git a/src/tools/clippy/Cargo.toml b/src/tools/clippy/Cargo.toml
index 40aaa5924df..ba3ed3053ac 100644
--- a/src/tools/clippy/Cargo.toml
+++ b/src/tools/clippy/Cargo.toml
@@ -8,7 +8,7 @@ license = "MIT OR Apache-2.0"
 keywords = ["clippy", "lint", "plugin"]
 categories = ["development-tools", "development-tools::cargo-plugins"]
 build = "build.rs"
-edition = "2018"
+edition = "2021"
 publish = false
 
 [[bin]]
diff --git a/src/tools/clippy/README.md b/src/tools/clippy/README.md
index aaf404eadea..822335fc65f 100644
--- a/src/tools/clippy/README.md
+++ b/src/tools/clippy/README.md
@@ -18,7 +18,7 @@ You can choose how much Clippy is supposed to ~~annoy~~ help you by changing the
 | `clippy::style`       | code that should be written in a more idiomatic way                                 | **warn**      |
 | `clippy::complexity`  | code that does something simple but in a complex way                                | **warn**      |
 | `clippy::perf`        | code that can be written to run faster                                              | **warn**      |
-| `clippy::pedantic`    | lints which are rather strict or might have false positives                         | allow         |
+| `clippy::pedantic`    | lints which are rather strict or have occasional false positives                    | allow         |
 | `clippy::nursery`     | new lints that are still under development                                          | allow         |
 | `clippy::cargo`       | lints for the cargo manifest                                                        | allow         |
 
diff --git a/src/tools/clippy/clippy_dev/Cargo.toml b/src/tools/clippy/clippy_dev/Cargo.toml
index d7d2655026b..4a13a452409 100644
--- a/src/tools/clippy/clippy_dev/Cargo.toml
+++ b/src/tools/clippy/clippy_dev/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "clippy_dev"
 version = "0.0.1"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 bytecount = "0.6"
diff --git a/src/tools/clippy/clippy_dev/src/bless.rs b/src/tools/clippy/clippy_dev/src/bless.rs
index c4fa0a9aca7..daf0fcc993b 100644
--- a/src/tools/clippy/clippy_dev/src/bless.rs
+++ b/src/tools/clippy/clippy_dev/src/bless.rs
@@ -1,7 +1,6 @@
 //! `bless` updates the reference files in the repo with changed output files
 //! from the last test run.
 
-use std::env;
 use std::ffi::OsStr;
 use std::fs;
 use std::lazy::SyncLazy;
@@ -10,17 +9,9 @@ use walkdir::WalkDir;
 
 use crate::clippy_project_root;
 
-// NOTE: this is duplicated with tests/cargo/mod.rs What to do?
-pub static CARGO_TARGET_DIR: SyncLazy<PathBuf> = SyncLazy::new(|| match env::var_os("CARGO_TARGET_DIR") {
-    Some(v) => v.into(),
-    None => env::current_dir().unwrap().join("target"),
-});
-
 static CLIPPY_BUILD_TIME: SyncLazy<Option<std::time::SystemTime>> = SyncLazy::new(|| {
-    let profile = env::var("PROFILE").unwrap_or_else(|_| "debug".to_string());
-    let mut path = PathBuf::from(&**CARGO_TARGET_DIR);
-    path.push(profile);
-    path.push("cargo-clippy");
+    let mut path = std::env::current_exe().unwrap();
+    path.set_file_name("cargo-clippy");
     fs::metadata(path).ok()?.modified().ok()
 });
 
@@ -94,10 +85,7 @@ fn updated_since_clippy_build(path: &Path) -> Option<bool> {
 }
 
 fn build_dir() -> PathBuf {
-    let profile = env::var("PROFILE").unwrap_or_else(|_| "debug".to_string());
-    let mut path = PathBuf::new();
-    path.push(CARGO_TARGET_DIR.clone());
-    path.push(profile);
-    path.push("test_build_base");
+    let mut path = std::env::current_exe().unwrap();
+    path.set_file_name("test");
     path
 }
diff --git a/src/tools/clippy/clippy_lints/Cargo.toml b/src/tools/clippy/clippy_lints/Cargo.toml
index e59175a55e1..7900dc6d041 100644
--- a/src/tools/clippy/clippy_lints/Cargo.toml
+++ b/src/tools/clippy/clippy_lints/Cargo.toml
@@ -6,7 +6,7 @@ repository = "https://github.com/rust-lang/rust-clippy"
 readme = "README.md"
 license = "MIT OR Apache-2.0"
 keywords = ["clippy", "lint", "plugin"]
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 cargo_metadata = "0.12"
diff --git a/src/tools/clippy/clippy_lints/src/derivable_impls.rs b/src/tools/clippy/clippy_lints/src/derivable_impls.rs
index b4c4ca016aa..15252ef96cd 100644
--- a/src/tools/clippy/clippy_lints/src/derivable_impls.rs
+++ b/src/tools/clippy/clippy_lints/src/derivable_impls.rs
@@ -2,10 +2,9 @@ use clippy_utils::diagnostics::span_lint_and_help;
 use clippy_utils::{in_macro, is_automatically_derived, is_default_equivalent, remove_blocks};
 use rustc_hir::{
     def::{DefKind, Res},
-    Body, Expr, ExprKind, Impl, ImplItemKind, Item, ItemKind, Node, QPath,
+    Body, Expr, ExprKind, GenericArg, Impl, ImplItemKind, Item, ItemKind, Node, PathSegment, QPath, TyKind,
 };
 use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::ty::TypeFoldable;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::sym;
 
@@ -68,6 +67,7 @@ impl<'tcx> LateLintPass<'tcx> for DerivableImpls {
             if let ItemKind::Impl(Impl {
                 of_trait: Some(ref trait_ref),
                 items: [child],
+                self_ty,
                 ..
             }) = item.kind;
             if let attrs = cx.tcx.hir().attrs(item.hir_id());
@@ -80,9 +80,18 @@ impl<'tcx> LateLintPass<'tcx> for DerivableImpls {
             if let ImplItemKind::Fn(_, b) = &impl_item.kind;
             if let Body { value: func_expr, .. } = cx.tcx.hir().body(*b);
             if let Some(adt_def) = cx.tcx.type_of(item.def_id).ty_adt_def();
+            if !attrs.iter().any(|attr| attr.doc_str().is_some());
+            if let child_attrs = cx.tcx.hir().attrs(impl_item_hir);
+            if !child_attrs.iter().any(|attr| attr.doc_str().is_some());
             then {
-                if cx.tcx.type_of(item.def_id).definitely_has_param_types_or_consts(cx.tcx) {
-                    return;
+                if let TyKind::Path(QPath::Resolved(_, p)) = self_ty.kind {
+                    if let Some(PathSegment { args: Some(a), .. }) = p.segments.last() {
+                        for arg in a.args {
+                            if !matches!(arg, GenericArg::Lifetime(_)) {
+                                return;
+                            }
+                        }
+                    }
                 }
                 let should_emit = match remove_blocks(func_expr).kind {
                     ExprKind::Tup(fields) => fields.iter().all(|e| is_default_equivalent(cx, e)),
diff --git a/src/tools/clippy/clippy_lints/src/disallowed_method.rs b/src/tools/clippy/clippy_lints/src/disallowed_method.rs
index 7069cb4198c..1167b26c8f1 100644
--- a/src/tools/clippy/clippy_lints/src/disallowed_method.rs
+++ b/src/tools/clippy/clippy_lints/src/disallowed_method.rs
@@ -1,33 +1,44 @@
-use clippy_utils::diagnostics::span_lint;
+use clippy_utils::diagnostics::span_lint_and_then;
 use clippy_utils::fn_def_id;
 
-use rustc_data_structures::fx::FxHashSet;
-use rustc_hir::{def::Res, def_id::DefId, Crate, Expr};
+use rustc_hir::{def::Res, def_id::DefIdMap, Crate, Expr};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
-use rustc_span::Symbol;
+
+use crate::utils::conf;
 
 declare_clippy_lint! {
     /// ### What it does
     /// Denies the configured methods and functions in clippy.toml
     ///
     /// ### Why is this bad?
-    /// Some methods are undesirable in certain contexts,
-    /// and it's beneficial to lint for them as needed.
+    /// Some methods are undesirable in certain contexts, and it's beneficial to
+    /// lint for them as needed.
     ///
     /// ### Example
     /// An example clippy.toml configuration:
     /// ```toml
     /// # clippy.toml
-    /// disallowed-methods = ["std::vec::Vec::leak", "std::time::Instant::now"]
+    /// disallowed-methods = [
+    ///     # Can use a string as the path of the disallowed method.
+    ///     "std::boxed::Box::new",
+    ///     # Can also use an inline table with a `path` key.
+    ///     { path = "std::time::Instant::now" },
+    ///     # When using an inline table, can add a `reason` for why the method
+    ///     # is disallowed.
+    ///     { path = "std::vec::Vec::leak", reason = "no leaking memory" },
+    /// ]
     /// ```
     ///
     /// ```rust,ignore
     /// // Example code where clippy issues a warning
     /// let xs = vec![1, 2, 3, 4];
     /// xs.leak(); // Vec::leak is disallowed in the config.
+    /// // The diagnostic contains the message "no leaking memory".
     ///
     /// let _now = Instant::now(); // Instant::now is disallowed in the config.
+    ///
+    /// let _box = Box::new(3); // Box::new is disallowed in the config.
     /// ```
     ///
     /// Use instead:
@@ -43,18 +54,15 @@ declare_clippy_lint! {
 
 #[derive(Clone, Debug)]
 pub struct DisallowedMethod {
-    disallowed: FxHashSet<Vec<Symbol>>,
-    def_ids: FxHashSet<(DefId, Vec<Symbol>)>,
+    conf_disallowed: Vec<conf::DisallowedMethod>,
+    disallowed: DefIdMap<Option<String>>,
 }
 
 impl DisallowedMethod {
-    pub fn new(disallowed: &FxHashSet<String>) -> Self {
+    pub fn new(conf_disallowed: Vec<conf::DisallowedMethod>) -> Self {
         Self {
-            disallowed: disallowed
-                .iter()
-                .map(|s| s.split("::").map(|seg| Symbol::intern(seg)).collect::<Vec<_>>())
-                .collect(),
-            def_ids: FxHashSet::default(),
+            conf_disallowed,
+            disallowed: DefIdMap::default(),
         }
     }
 }
@@ -63,32 +71,36 @@ impl_lint_pass!(DisallowedMethod => [DISALLOWED_METHOD]);
 
 impl<'tcx> LateLintPass<'tcx> for DisallowedMethod {
     fn check_crate(&mut self, cx: &LateContext<'_>, _: &Crate<'_>) {
-        for path in &self.disallowed {
-            let segs = path.iter().map(ToString::to_string).collect::<Vec<_>>();
-            if let Res::Def(_, id) = clippy_utils::path_to_res(cx, &segs.iter().map(String::as_str).collect::<Vec<_>>())
-            {
-                self.def_ids.insert((id, path.clone()));
+        for conf in &self.conf_disallowed {
+            let (path, reason) = match conf {
+                conf::DisallowedMethod::Simple(path) => (path, None),
+                conf::DisallowedMethod::WithReason { path, reason } => (
+                    path,
+                    reason.as_ref().map(|reason| format!("{} (from clippy.toml)", reason)),
+                ),
+            };
+            let segs: Vec<_> = path.split("::").collect();
+            if let Res::Def(_, id) = clippy_utils::path_to_res(cx, &segs) {
+                self.disallowed.insert(id, reason);
             }
         }
     }
 
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
-        if let Some(def_id) = fn_def_id(cx, expr) {
-            if self.def_ids.iter().any(|(id, _)| def_id == *id) {
-                let func_path = cx.get_def_path(def_id);
-                let func_path_string = func_path
-                    .into_iter()
-                    .map(Symbol::to_ident_string)
-                    .collect::<Vec<_>>()
-                    .join("::");
-
-                span_lint(
-                    cx,
-                    DISALLOWED_METHOD,
-                    expr.span,
-                    &format!("use of a disallowed method `{}`", func_path_string),
-                );
+        let def_id = match fn_def_id(cx, expr) {
+            Some(def_id) => def_id,
+            None => return,
+        };
+        let reason = match self.disallowed.get(&def_id) {
+            Some(reason) => reason,
+            None => return,
+        };
+        let func_path = cx.tcx.def_path_str(def_id);
+        let msg = format!("use of a disallowed method `{}`", func_path);
+        span_lint_and_then(cx, DISALLOWED_METHOD, expr.span, &msg, |diag| {
+            if let Some(reason) = reason {
+                diag.note(reason);
             }
-        }
+        });
     }
 }
diff --git a/src/tools/clippy/clippy_lints/src/disallowed_type.rs b/src/tools/clippy/clippy_lints/src/disallowed_type.rs
index e627168b932..6c861fb33a9 100644
--- a/src/tools/clippy/clippy_lints/src/disallowed_type.rs
+++ b/src/tools/clippy/clippy_lints/src/disallowed_type.rs
@@ -48,7 +48,7 @@ impl DisallowedType {
         Self {
             disallowed: disallowed
                 .iter()
-                .map(|s| s.split("::").map(|seg| Symbol::intern(seg)).collect::<Vec<_>>())
+                .map(|s| s.split("::").map(Symbol::intern).collect::<Vec<_>>())
                 .collect(),
             def_ids: FxHashSet::default(),
             prim_tys: FxHashSet::default(),
diff --git a/src/tools/clippy/clippy_lints/src/escape.rs b/src/tools/clippy/clippy_lints/src/escape.rs
index 6bbac6d9a24..090be73af3b 100644
--- a/src/tools/clippy/clippy_lints/src/escape.rs
+++ b/src/tools/clippy/clippy_lints/src/escape.rs
@@ -91,8 +91,11 @@ impl<'tcx> LateLintPass<'tcx> for BoxedLocal {
                     if trait_item.id.hir_id() == hir_id {
                         // be sure we have `self` parameter in this function
                         if let AssocItemKind::Fn { has_self: true } = trait_item.kind {
-                            trait_self_ty =
-                                Some(TraitRef::identity(cx.tcx, trait_item.id.def_id.to_def_id()).self_ty().skip_binder());
+                            trait_self_ty = Some(
+                                TraitRef::identity(cx.tcx, trait_item.id.def_id.to_def_id())
+                                    .self_ty()
+                                    .skip_binder(),
+                            );
                         }
                     }
                 }
diff --git a/src/tools/clippy/clippy_lints/src/eta_reduction.rs b/src/tools/clippy/clippy_lints/src/eta_reduction.rs
index f6a64a8ca60..9df92cc5b64 100644
--- a/src/tools/clippy/clippy_lints/src/eta_reduction.rs
+++ b/src/tools/clippy/clippy_lints/src/eta_reduction.rs
@@ -1,16 +1,16 @@
 use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
 use clippy_utils::higher::VecArgs;
 use clippy_utils::source::snippet_opt;
-use clippy_utils::ty::{implements_trait, type_is_unsafe_function};
 use clippy_utils::usage::UsedAfterExprVisitor;
-use clippy_utils::{get_enclosing_loop_or_closure, higher};
-use clippy_utils::{is_adjusted, iter_input_pats};
+use clippy_utils::{get_enclosing_loop_or_closure, higher, path_to_local_id};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
-use rustc_hir::{def_id, Expr, ExprKind, Param, PatKind, QPath};
-use rustc_lint::{LateContext, LateLintPass, LintContext};
-use rustc_middle::lint::in_external_macro;
-use rustc_middle::ty::{self, ClosureKind, Ty};
+use rustc_hir::def_id::DefId;
+use rustc_hir::{Expr, ExprKind, Param, PatKind, Unsafety};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow};
+use rustc_middle::ty::subst::Subst;
+use rustc_middle::ty::{self, ClosureKind, Ty, TypeFoldable};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 
 declare_clippy_lint! {
@@ -52,12 +52,6 @@ declare_clippy_lint! {
     /// ### Why is this bad?
     /// It's unnecessary to create the closure.
     ///
-    /// ### Known problems
-    /// [#3071](https://github.com/rust-lang/rust-clippy/issues/3071),
-    /// [#3942](https://github.com/rust-lang/rust-clippy/issues/3942),
-    /// [#4002](https://github.com/rust-lang/rust-clippy/issues/4002)
-    ///
-    ///
     /// ### Example
     /// ```rust,ignore
     /// Some('a').map(|s| s.to_uppercase());
@@ -75,32 +69,16 @@ declare_lint_pass!(EtaReduction => [REDUNDANT_CLOSURE, REDUNDANT_CLOSURE_FOR_MET
 
 impl<'tcx> LateLintPass<'tcx> for EtaReduction {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
-        if in_external_macro(cx.sess(), expr.span) {
+        if expr.span.from_expansion() {
             return;
         }
-
-        match expr.kind {
-            ExprKind::Call(_, args) | ExprKind::MethodCall(_, _, args, _) => {
-                for arg in args {
-                    // skip `foo(macro!())`
-                    if arg.span.ctxt() == expr.span.ctxt() {
-                        check_closure(cx, arg);
-                    }
-                }
-            },
-            _ => (),
-        }
-    }
-}
-
-fn check_closure<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
-    if let ExprKind::Closure(_, decl, eid, _, _) = expr.kind {
-        let body = cx.tcx.hir().body(eid);
-        let ex = &body.value;
-
-        if ex.span.ctxt() != expr.span.ctxt() {
-            if decl.inputs.is_empty() {
-                if let Some(VecArgs::Vec(&[])) = higher::VecArgs::hir(cx, ex) {
+        let body = match expr.kind {
+            ExprKind::Closure(_, _, id, _, _) => cx.tcx.hir().body(id),
+            _ => return,
+        };
+        if body.value.span.from_expansion() {
+            if body.params.is_empty() {
+                if let Some(VecArgs::Vec(&[])) = higher::VecArgs::hir(cx, &body.value) {
                     // replace `|| vec![]` with `Vec::new`
                     span_lint_and_sugg(
                         cx,
@@ -117,33 +95,30 @@ fn check_closure<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
             return;
         }
 
-        if_chain!(
-            if let ExprKind::Call(caller, args) = ex.kind;
-
-            if let ExprKind::Path(_) = caller.kind;
-
-            // Not the same number of arguments, there is no way the closure is the same as the function return;
-            if args.len() == decl.inputs.len();
-
-            // Are the expression or the arguments type-adjusted? Then we need the closure
-            if !(is_adjusted(cx, ex) || args.iter().any(|arg| is_adjusted(cx, arg)));
-
-            let fn_ty = cx.typeck_results().expr_ty(caller);
-
-            if matches!(fn_ty.kind(), ty::FnDef(_, _) | ty::FnPtr(_) | ty::Closure(_, _));
-
-            if !type_is_unsafe_function(cx, fn_ty);
-
-            if compare_inputs(&mut iter_input_pats(decl, body), &mut args.iter());
+        let closure_ty = cx.typeck_results().expr_ty(expr);
 
+        if_chain!(
+            if let ExprKind::Call(callee, args) = body.value.kind;
+            if let ExprKind::Path(_) = callee.kind;
+            if check_inputs(cx, body.params, args);
+            let callee_ty = cx.typeck_results().expr_ty_adjusted(callee);
+            let call_ty = cx.typeck_results().type_dependent_def_id(body.value.hir_id)
+                .map_or(callee_ty, |id| cx.tcx.type_of(id));
+            if check_sig(cx, closure_ty, call_ty);
+            let substs = cx.typeck_results().node_substs(callee.hir_id);
+            // This fixes some false positives that I don't entirely understand
+            if substs.is_empty() || !cx.typeck_results().expr_ty(expr).has_late_bound_regions();
+            // A type param function ref like `T::f` is not 'static, however
+            // it is if cast like `T::f as fn()`. This seems like a rustc bug.
+            if !substs.types().any(|t| matches!(t.kind(), ty::Param(_)));
             then {
                 span_lint_and_then(cx, REDUNDANT_CLOSURE, expr.span, "redundant closure", |diag| {
-                    if let Some(mut snippet) = snippet_opt(cx, caller.span) {
+                    if let Some(mut snippet) = snippet_opt(cx, callee.span) {
                         if_chain! {
-                            if let ty::Closure(_, substs) = fn_ty.kind();
+                            if let ty::Closure(_, substs) = callee_ty.peel_refs().kind();
                             if let ClosureKind::FnMut = substs.as_closure().kind();
-                            if UsedAfterExprVisitor::is_found(cx, caller)
-                                || get_enclosing_loop_or_closure(cx.tcx, expr).is_some();
+                            if get_enclosing_loop_or_closure(cx.tcx, expr).is_some()
+                                || UsedAfterExprVisitor::is_found(cx, callee);
 
                             then {
                                 // Mutable closure is used after current expr; we cannot consume it.
@@ -162,110 +137,79 @@ fn check_closure<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         );
 
         if_chain!(
-            if let ExprKind::MethodCall(path, _, args, _) = ex.kind;
-
-            // Not the same number of arguments, there is no way the closure is the same as the function return;
-            if args.len() == decl.inputs.len();
-
-            // Are the expression or the arguments type-adjusted? Then we need the closure
-            if !(is_adjusted(cx, ex) || args.iter().skip(1).any(|arg| is_adjusted(cx, arg)));
-
-            let method_def_id = cx.typeck_results().type_dependent_def_id(ex.hir_id).unwrap();
-            if !type_is_unsafe_function(cx, cx.tcx.type_of(method_def_id));
-
-            if compare_inputs(&mut iter_input_pats(decl, body), &mut args.iter());
-
-            if let Some(name) = get_ufcs_type_name(cx, method_def_id, &args[0]);
-
+            if let ExprKind::MethodCall(path, _, args, _) = body.value.kind;
+            if check_inputs(cx, body.params, args);
+            let method_def_id = cx.typeck_results().type_dependent_def_id(body.value.hir_id).unwrap();
+            let substs = cx.typeck_results().node_substs(body.value.hir_id);
+            let call_ty = cx.tcx.type_of(method_def_id).subst(cx.tcx, substs);
+            if check_sig(cx, closure_ty, call_ty);
             then {
-                span_lint_and_sugg(
-                    cx,
-                    REDUNDANT_CLOSURE_FOR_METHOD_CALLS,
-                    expr.span,
-                    "redundant closure",
-                    "replace the closure with the method itself",
-                    format!("{}::{}", name, path.ident.name),
-                    Applicability::MachineApplicable,
-                );
+                span_lint_and_then(cx, REDUNDANT_CLOSURE_FOR_METHOD_CALLS, expr.span, "redundant closure", |diag| {
+                    let name = get_ufcs_type_name(cx, method_def_id);
+                    diag.span_suggestion(
+                        expr.span,
+                        "replace the closure with the method itself",
+                        format!("{}::{}", name, path.ident.name),
+                        Applicability::MachineApplicable,
+                    );
+                })
             }
         );
     }
 }
 
-/// Tries to determine the type for universal function call to be used instead of the closure
-fn get_ufcs_type_name(cx: &LateContext<'_>, method_def_id: def_id::DefId, self_arg: &Expr<'_>) -> Option<String> {
-    let expected_type_of_self = &cx.tcx.fn_sig(method_def_id).inputs_and_output().skip_binder()[0];
-    let actual_type_of_self = &cx.typeck_results().node_type(self_arg.hir_id);
-
-    if let Some(trait_id) = cx.tcx.trait_of_item(method_def_id) {
-        if match_borrow_depth(expected_type_of_self, actual_type_of_self)
-            && implements_trait(cx, actual_type_of_self, trait_id, &[])
-        {
-            return Some(cx.tcx.def_path_str(trait_id));
-        }
+fn check_inputs(cx: &LateContext<'_>, params: &[Param<'_>], call_args: &[Expr<'_>]) -> bool {
+    if params.len() != call_args.len() {
+        return false;
     }
-
-    cx.tcx.impl_of_method(method_def_id).and_then(|_| {
-        //a type may implicitly implement other type's methods (e.g. Deref)
-        if match_types(expected_type_of_self, actual_type_of_self) {
-            Some(get_type_name(cx, actual_type_of_self))
-        } else {
-            None
+    std::iter::zip(params, call_args).all(|(param, arg)| {
+        match param.pat.kind {
+            PatKind::Binding(_, id, ..) if path_to_local_id(arg, id) => {},
+            _ => return false,
+        }
+        match *cx.typeck_results().expr_adjustments(arg) {
+            [] => true,
+            [Adjustment {
+                kind: Adjust::Deref(None),
+                ..
+            }, Adjustment {
+                kind: Adjust::Borrow(AutoBorrow::Ref(_, mu2)),
+                ..
+            }] => {
+                // re-borrow with the same mutability is allowed
+                let ty = cx.typeck_results().expr_ty(arg);
+                matches!(*ty.kind(), ty::Ref(.., mu1) if mu1 == mu2.into())
+            },
+            _ => false,
         }
     })
 }
 
-fn match_borrow_depth(lhs: Ty<'_>, rhs: Ty<'_>) -> bool {
-    match (&lhs.kind(), &rhs.kind()) {
-        (ty::Ref(_, t1, mut1), ty::Ref(_, t2, mut2)) => mut1 == mut2 && match_borrow_depth(t1, t2),
-        (l, r) => !matches!((l, r), (ty::Ref(_, _, _), _) | (_, ty::Ref(_, _, _))),
-    }
-}
-
-fn match_types(lhs: Ty<'_>, rhs: Ty<'_>) -> bool {
-    match (&lhs.kind(), &rhs.kind()) {
-        (ty::Bool, ty::Bool)
-        | (ty::Char, ty::Char)
-        | (ty::Int(_), ty::Int(_))
-        | (ty::Uint(_), ty::Uint(_))
-        | (ty::Str, ty::Str) => true,
-        (ty::Ref(_, t1, mut1), ty::Ref(_, t2, mut2)) => mut1 == mut2 && match_types(t1, t2),
-        (ty::Array(t1, _), ty::Array(t2, _)) | (ty::Slice(t1), ty::Slice(t2)) => match_types(t1, t2),
-        (ty::Adt(def1, _), ty::Adt(def2, _)) => def1 == def2,
-        (_, _) => false,
+fn check_sig<'tcx>(cx: &LateContext<'tcx>, closure_ty: Ty<'tcx>, call_ty: Ty<'tcx>) -> bool {
+    let call_sig = call_ty.fn_sig(cx.tcx);
+    if call_sig.unsafety() == Unsafety::Unsafe {
+        return false;
     }
-}
-
-fn get_type_name(cx: &LateContext<'_>, ty: Ty<'_>) -> String {
-    match ty.kind() {
-        ty::Adt(t, _) => cx.tcx.def_path_str(t.did),
-        ty::Ref(_, r, _) => get_type_name(cx, r),
-        _ => ty.to_string(),
+    if !closure_ty.has_late_bound_regions() {
+        return true;
     }
+    let substs = match closure_ty.kind() {
+        ty::Closure(_, substs) => substs,
+        _ => return false,
+    };
+    let closure_sig = cx.tcx.signature_unclosure(substs.as_closure().sig(), Unsafety::Normal);
+    cx.tcx.erase_late_bound_regions(closure_sig) == cx.tcx.erase_late_bound_regions(call_sig)
 }
 
-fn compare_inputs(
-    closure_inputs: &mut dyn Iterator<Item = &Param<'_>>,
-    call_args: &mut dyn Iterator<Item = &Expr<'_>>,
-) -> bool {
-    for (closure_input, function_arg) in closure_inputs.zip(call_args) {
-        if let PatKind::Binding(_, _, ident, _) = closure_input.pat.kind {
-            // XXXManishearth Should I be checking the binding mode here?
-            if let ExprKind::Path(QPath::Resolved(None, p)) = function_arg.kind {
-                if p.segments.len() != 1 {
-                    // If it's a proper path, it can't be a local variable
-                    return false;
-                }
-                if p.segments[0].ident.name != ident.name {
-                    // The two idents should be the same
-                    return false;
-                }
-            } else {
-                return false;
+fn get_ufcs_type_name(cx: &LateContext<'_>, method_def_id: DefId) -> String {
+    match cx.tcx.associated_item(method_def_id).container {
+        ty::TraitContainer(def_id) => cx.tcx.def_path_str(def_id),
+        ty::ImplContainer(def_id) => {
+            let ty = cx.tcx.type_of(def_id);
+            match ty.kind() {
+                ty::Adt(adt, _) => cx.tcx.def_path_str(adt.did),
+                _ => ty.to_string(),
             }
-        } else {
-            return false;
-        }
+        },
     }
-    true
 }
diff --git a/src/tools/clippy/clippy_lints/src/float_literal.rs b/src/tools/clippy/clippy_lints/src/float_literal.rs
index a3d70f31f00..1e8a5bd7d34 100644
--- a/src/tools/clippy/clippy_lints/src/float_literal.rs
+++ b/src/tools/clippy/clippy_lints/src/float_literal.rs
@@ -111,7 +111,7 @@ impl<'tcx> LateLintPass<'tcx> for FloatLiteral {
                             Applicability::MachineApplicable,
                         );
                     }
-                } else if digits > max as usize && sym_str != float_str {
+                } else if digits > max as usize && float_str.len() < sym_str.len() {
                     span_lint_and_sugg(
                         cx,
                         EXCESSIVE_PRECISION,
diff --git a/src/tools/clippy/clippy_lints/src/format.rs b/src/tools/clippy/clippy_lints/src/format.rs
index 863c606f5a9..508cac33848 100644
--- a/src/tools/clippy/clippy_lints/src/format.rs
+++ b/src/tools/clippy/clippy_lints/src/format.rs
@@ -69,8 +69,8 @@ impl<'tcx> LateLintPass<'tcx> for UselessFormat {
                     ty::Str => true,
                     _ => false,
                 };
-                if format_args.args.iter().all(|e| is_display_arg(e));
-                if format_args.fmt_expr.map_or(true, |e| check_unformatted(e));
+                if format_args.args.iter().all(is_display_arg);
+                if format_args.fmt_expr.map_or(true, check_unformatted);
                 then {
                     let is_new_string = match value.kind {
                         ExprKind::Binary(..) => true,
diff --git a/src/tools/clippy/clippy_lints/src/formatting.rs b/src/tools/clippy/clippy_lints/src/formatting.rs
index 4dd0ffe77ea..b4f186525c5 100644
--- a/src/tools/clippy/clippy_lints/src/formatting.rs
+++ b/src/tools/clippy/clippy_lints/src/formatting.rs
@@ -286,34 +286,39 @@ fn check_array(cx: &EarlyContext<'_>, expr: &Expr) {
 }
 
 fn check_missing_else(cx: &EarlyContext<'_>, first: &Expr, second: &Expr) {
-    if !differing_macro_contexts(first.span, second.span)
-        && !first.span.from_expansion()
-        && is_if(first)
-        && (is_block(second) || is_if(second))
-    {
-        // where the else would be
-        let else_span = first.span.between(second.span);
+    if_chain! {
+        if !differing_macro_contexts(first.span, second.span);
+        if !first.span.from_expansion();
+        if let ExprKind::If(cond_expr, ..) = &first.kind;
+        if is_block(second) || is_if(second);
 
-        if let Some(else_snippet) = snippet_opt(cx, else_span) {
-            if !else_snippet.contains('\n') {
-                let (looks_like, next_thing) = if is_if(second) {
-                    ("an `else if`", "the second `if`")
-                } else {
-                    ("an `else {..}`", "the next block")
-                };
+        // Proc-macros can give weird spans. Make sure this is actually an `if`.
+        if let Some(if_snip) = snippet_opt(cx, first.span.until(cond_expr.span));
+        if if_snip.starts_with("if");
 
-                span_lint_and_note(
-                    cx,
-                    SUSPICIOUS_ELSE_FORMATTING,
-                    else_span,
-                    &format!("this looks like {} but the `else` is missing", looks_like),
-                    None,
-                    &format!(
-                        "to remove this lint, add the missing `else` or add a new line before {}",
-                        next_thing,
-                    ),
-                );
-            }
+        // If there is a line break between the two expressions, don't lint.
+        // If there is a non-whitespace character, this span came from a proc-macro.
+        let else_span = first.span.between(second.span);
+        if let Some(else_snippet) = snippet_opt(cx, else_span);
+        if !else_snippet.chars().any(|c| c == '\n' || !c.is_whitespace());
+        then {
+            let (looks_like, next_thing) = if is_if(second) {
+                ("an `else if`", "the second `if`")
+            } else {
+                ("an `else {..}`", "the next block")
+            };
+
+            span_lint_and_note(
+                cx,
+                SUSPICIOUS_ELSE_FORMATTING,
+                else_span,
+                &format!("this looks like {} but the `else` is missing", looks_like),
+                None,
+                &format!(
+                    "to remove this lint, add the missing `else` or add a new line before {}",
+                    next_thing,
+                ),
+            );
         }
     }
 }
diff --git a/src/tools/clippy/clippy_lints/src/if_then_panic.rs b/src/tools/clippy/clippy_lints/src/if_then_panic.rs
new file mode 100644
index 00000000000..ee575c81a8b
--- /dev/null
+++ b/src/tools/clippy/clippy_lints/src/if_then_panic.rs
@@ -0,0 +1,97 @@
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::higher::PanicExpn;
+use clippy_utils::is_expn_of;
+use clippy_utils::source::snippet_with_applicability;
+use rustc_errors::Applicability;
+use rustc_hir::{Block, Expr, ExprKind, StmtKind, UnOp};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+
+declare_clippy_lint! {
+    /// ### What it does
+    /// Detects `if`-then-`panic!` that can be replaced with `assert!`.
+    ///
+    /// ### Why is this bad?
+    /// `assert!` is simpler than `if`-then-`panic!`.
+    ///
+    /// ### Example
+    /// ```rust
+    /// let sad_people: Vec<&str> = vec![];
+    /// if !sad_people.is_empty() {
+    ///     panic!("there are sad people: {:?}", sad_people);
+    /// }
+    /// ```
+    /// Use instead:
+    /// ```rust
+    /// let sad_people: Vec<&str> = vec![];
+    /// assert!(sad_people.is_empty(), "there are sad people: {:?}", sad_people);
+    /// ```
+    pub IF_THEN_PANIC,
+    style,
+    "`panic!` and only a `panic!` in `if`-then statement"
+}
+
+declare_lint_pass!(IfThenPanic => [IF_THEN_PANIC]);
+
+impl LateLintPass<'_> for IfThenPanic {
+    fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
+        if_chain! {
+            if let Expr {
+                kind: ExprKind:: If(cond, Expr {
+                    kind: ExprKind::Block(
+                        Block {
+                            stmts: [stmt],
+                            ..
+                        },
+                        _),
+                    ..
+                }, None),
+                ..
+            } = &expr;
+            if is_expn_of(stmt.span, "panic").is_some();
+            if !matches!(cond.kind, ExprKind::Let(_, _, _));
+            if let StmtKind::Semi(semi) = stmt.kind;
+            if !cx.tcx.sess.source_map().is_multiline(cond.span);
+
+            then {
+                let span = if let Some(panic_expn) = PanicExpn::parse(semi) {
+                    match *panic_expn.format_args.value_args {
+                        [] => panic_expn.format_args.format_string_span,
+                        [.., last] => panic_expn.format_args.format_string_span.to(last.span),
+                    }
+                } else {
+                    if_chain! {
+                        if let ExprKind::Block(block, _) = semi.kind;
+                        if let Some(init) = block.expr;
+                        if let ExprKind::Call(_, [format_args]) = init.kind;
+
+                        then {
+                            format_args.span
+                        } else {
+                            return
+                        }
+                    }
+                };
+                let mut applicability = Applicability::MachineApplicable;
+                let sugg = snippet_with_applicability(cx, span, "..", &mut applicability);
+
+                let cond_sugg =
+                if let ExprKind::DropTemps(Expr{kind: ExprKind::Unary(UnOp::Not, not_expr), ..}) = cond.kind {
+                    snippet_with_applicability(cx, not_expr.span, "..", &mut applicability).to_string()
+                } else {
+                    format!("!{}", snippet_with_applicability(cx, cond.span, "..", &mut applicability))
+                };
+
+                span_lint_and_sugg(
+                    cx,
+                    IF_THEN_PANIC,
+                    expr.span,
+                    "only a `panic!` in `if`-then statement",
+                    "try",
+                    format!("assert!({}, {});", cond_sugg, sugg),
+                    Applicability::MachineApplicable,
+                );
+            }
+        }
+    }
+}
diff --git a/src/tools/clippy/clippy_lints/src/iter_not_returning_iterator.rs b/src/tools/clippy/clippy_lints/src/iter_not_returning_iterator.rs
new file mode 100644
index 00000000000..6c779348ca2
--- /dev/null
+++ b/src/tools/clippy/clippy_lints/src/iter_not_returning_iterator.rs
@@ -0,0 +1,64 @@
+use clippy_utils::{diagnostics::span_lint, return_ty, ty::implements_trait};
+use rustc_hir::{ImplItem, ImplItemKind};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::symbol::kw;
+use rustc_span::symbol::sym;
+
+declare_clippy_lint! {
+    /// ### What it does
+    /// Detects methods named `iter` or `iter_mut` that do not have a return type that implements `Iterator`.
+    ///
+    /// ### Why is this bad?
+    /// Methods named `iter` or `iter_mut` conventionally return an `Iterator`.
+    ///
+    /// ### Example
+    /// ```rust
+    /// // `String` does not implement `Iterator`
+    /// struct Data {}
+    /// impl Data {
+    ///     fn iter(&self) -> String {
+    ///         todo!()
+    ///     }
+    /// }
+    /// ```
+    /// Use instead:
+    /// ```rust
+    /// use std::str::Chars;
+    /// struct Data {}
+    /// impl Data {
+    ///    fn iter(&self) -> Chars<'static> {
+    ///        todo!()
+    ///    }
+    /// }
+    /// ```
+    pub ITER_NOT_RETURNING_ITERATOR,
+    pedantic,
+    "methods named `iter` or `iter_mut` that do not return an `Iterator`"
+}
+
+declare_lint_pass!(IterNotReturningIterator => [ITER_NOT_RETURNING_ITERATOR]);
+
+impl LateLintPass<'_> for IterNotReturningIterator {
+    fn check_impl_item(&mut self, cx: &LateContext<'tcx>, impl_item: &'tcx ImplItem<'tcx>) {
+        let name: &str = &impl_item.ident.name.as_str();
+        if_chain! {
+            if let ImplItemKind::Fn(fn_sig, _) = &impl_item.kind;
+            let ret_ty = return_ty(cx, impl_item.hir_id());
+            if matches!(name, "iter" | "iter_mut");
+            if let [param] = cx.tcx.fn_arg_names(impl_item.def_id);
+            if param.name == kw::SelfLower;
+            if let Some(iter_trait_id) = cx.tcx.get_diagnostic_item(sym::Iterator);
+            if !implements_trait(cx, ret_ty, iter_trait_id, &[]);
+
+            then {
+                span_lint(
+                    cx,
+                    ITER_NOT_RETURNING_ITERATOR,
+                    fn_sig.span,
+                    &format!("this method is named `{}` but its return type does not implement `Iterator`", name),
+                );
+            }
+        }
+    }
+}
diff --git a/src/tools/clippy/clippy_lints/src/lib.rs b/src/tools/clippy/clippy_lints/src/lib.rs
index acc78840bb9..89724917482 100644
--- a/src/tools/clippy/clippy_lints/src/lib.rs
+++ b/src/tools/clippy/clippy_lints/src/lib.rs
@@ -225,8 +225,8 @@ mod future_not_send;
 mod get_last_with_len;
 mod identity_op;
 mod if_let_mutex;
-mod if_let_some_result;
 mod if_not_else;
+mod if_then_panic;
 mod if_then_some_else_none;
 mod implicit_hasher;
 mod implicit_return;
@@ -241,6 +241,7 @@ mod int_plus_one;
 mod integer_division;
 mod invalid_upcast_comparisons;
 mod items_after_statements;
+mod iter_not_returning_iterator;
 mod large_const_arrays;
 mod large_enum_variant;
 mod large_stack_arrays;
@@ -262,6 +263,7 @@ mod map_clone;
 mod map_err_ignore;
 mod map_unit_fn;
 mod match_on_vec_items;
+mod match_result_ok;
 mod matches;
 mod mem_discriminant;
 mod mem_forget;
@@ -330,6 +332,7 @@ mod reference;
 mod regex;
 mod repeat_once;
 mod returns;
+mod same_name_method;
 mod self_assignment;
 mod self_named_constructors;
 mod semicolon_if_nothing_returned;
@@ -655,8 +658,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         get_last_with_len::GET_LAST_WITH_LEN,
         identity_op::IDENTITY_OP,
         if_let_mutex::IF_LET_MUTEX,
-        if_let_some_result::IF_LET_SOME_RESULT,
         if_not_else::IF_NOT_ELSE,
+        if_then_panic::IF_THEN_PANIC,
         if_then_some_else_none::IF_THEN_SOME_ELSE_NONE,
         implicit_hasher::IMPLICIT_HASHER,
         implicit_return::IMPLICIT_RETURN,
@@ -674,6 +677,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         integer_division::INTEGER_DIVISION,
         invalid_upcast_comparisons::INVALID_UPCAST_COMPARISONS,
         items_after_statements::ITEMS_AFTER_STATEMENTS,
+        iter_not_returning_iterator::ITER_NOT_RETURNING_ITERATOR,
         large_const_arrays::LARGE_CONST_ARRAYS,
         large_enum_variant::LARGE_ENUM_VARIANT,
         large_stack_arrays::LARGE_STACK_ARRAYS,
@@ -723,6 +727,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         map_unit_fn::OPTION_MAP_UNIT_FN,
         map_unit_fn::RESULT_MAP_UNIT_FN,
         match_on_vec_items::MATCH_ON_VEC_ITEMS,
+        match_result_ok::MATCH_RESULT_OK,
         matches::INFALLIBLE_DESTRUCTURING_MATCH,
         matches::MATCH_AS_REF,
         matches::MATCH_BOOL,
@@ -908,6 +913,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         repeat_once::REPEAT_ONCE,
         returns::LET_AND_RETURN,
         returns::NEEDLESS_RETURN,
+        same_name_method::SAME_NAME_METHOD,
         self_assignment::SELF_ASSIGNMENT,
         self_named_constructors::SELF_NAMED_CONSTRUCTORS,
         semicolon_if_nothing_returned::SEMICOLON_IF_NOTHING_RETURNED,
@@ -952,7 +958,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         transmuting_null::TRANSMUTING_NULL,
         try_err::TRY_ERR,
         types::BORROWED_BOX,
-        types::BOX_VEC,
+        types::BOX_COLLECTION,
         types::LINKEDLIST,
         types::OPTION_OPTION,
         types::RC_BUFFER,
@@ -1051,6 +1057,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(panic_unimplemented::UNIMPLEMENTED),
         LintId::of(panic_unimplemented::UNREACHABLE),
         LintId::of(pattern_type_mismatch::PATTERN_TYPE_MISMATCH),
+        LintId::of(same_name_method::SAME_NAME_METHOD),
         LintId::of(shadow::SHADOW_REUSE),
         LintId::of(shadow::SHADOW_SAME),
         LintId::of(strings::STRING_ADD),
@@ -1104,6 +1111,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(infinite_iter::MAYBE_INFINITE_ITER),
         LintId::of(invalid_upcast_comparisons::INVALID_UPCAST_COMPARISONS),
         LintId::of(items_after_statements::ITEMS_AFTER_STATEMENTS),
+        LintId::of(iter_not_returning_iterator::ITER_NOT_RETURNING_ITERATOR),
         LintId::of(large_stack_arrays::LARGE_STACK_ARRAYS),
         LintId::of(let_underscore::LET_UNDERSCORE_DROP),
         LintId::of(literal_representation::LARGE_DIGIT_GROUPS),
@@ -1126,6 +1134,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(methods::INEFFICIENT_TO_STRING),
         LintId::of(methods::MAP_FLATTEN),
         LintId::of(methods::MAP_UNWRAP_OR),
+        LintId::of(misc::FLOAT_CMP),
         LintId::of(misc::USED_UNDERSCORE_BINDING),
         LintId::of(misc_early::UNSEPARATED_LITERAL_SUFFIX),
         LintId::of(mut_mut::MUT_MUT),
@@ -1134,6 +1143,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(needless_continue::NEEDLESS_CONTINUE),
         LintId::of(needless_for_each::NEEDLESS_FOR_EACH),
         LintId::of(needless_pass_by_value::NEEDLESS_PASS_BY_VALUE),
+        LintId::of(non_expressive_names::MANY_SINGLE_CHAR_NAMES),
         LintId::of(non_expressive_names::SIMILAR_NAMES),
         LintId::of(pass_by_ref_or_value::LARGE_TYPES_PASSED_BY_VALUE),
         LintId::of(pass_by_ref_or_value::TRIVIALLY_COPY_PASS_BY_REF),
@@ -1249,7 +1259,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(get_last_with_len::GET_LAST_WITH_LEN),
         LintId::of(identity_op::IDENTITY_OP),
         LintId::of(if_let_mutex::IF_LET_MUTEX),
-        LintId::of(if_let_some_result::IF_LET_SOME_RESULT),
+        LintId::of(if_then_panic::IF_THEN_PANIC),
         LintId::of(indexing_slicing::OUT_OF_BOUNDS_INDEXING),
         LintId::of(infinite_iter::INFINITE_ITER),
         LintId::of(inherent_to_string::INHERENT_TO_STRING),
@@ -1292,6 +1302,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(map_clone::MAP_CLONE),
         LintId::of(map_unit_fn::OPTION_MAP_UNIT_FN),
         LintId::of(map_unit_fn::RESULT_MAP_UNIT_FN),
+        LintId::of(match_result_ok::MATCH_RESULT_OK),
         LintId::of(matches::INFALLIBLE_DESTRUCTURING_MATCH),
         LintId::of(matches::MATCH_AS_REF),
         LintId::of(matches::MATCH_LIKE_MATCHES_MACRO),
@@ -1358,7 +1369,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(minmax::MIN_MAX),
         LintId::of(misc::CMP_NAN),
         LintId::of(misc::CMP_OWNED),
-        LintId::of(misc::FLOAT_CMP),
         LintId::of(misc::MODULO_ONE),
         LintId::of(misc::SHORT_CIRCUIT_STATEMENT),
         LintId::of(misc::TOPLEVEL_REF_ARG),
@@ -1390,7 +1400,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(non_copy_const::BORROW_INTERIOR_MUTABLE_CONST),
         LintId::of(non_copy_const::DECLARE_INTERIOR_MUTABLE_CONST),
         LintId::of(non_expressive_names::JUST_UNDERSCORES_AND_DIGITS),
-        LintId::of(non_expressive_names::MANY_SINGLE_CHAR_NAMES),
         LintId::of(non_octal_unix_permissions::NON_OCTAL_UNIX_PERMISSIONS),
         LintId::of(open_options::NONSENSICAL_OPEN_OPTIONS),
         LintId::of(option_env_unwrap::OPTION_ENV_UNWRAP),
@@ -1448,7 +1457,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(transmuting_null::TRANSMUTING_NULL),
         LintId::of(try_err::TRY_ERR),
         LintId::of(types::BORROWED_BOX),
-        LintId::of(types::BOX_VEC),
+        LintId::of(types::BOX_COLLECTION),
         LintId::of(types::REDUNDANT_ALLOCATION),
         LintId::of(types::TYPE_COMPLEXITY),
         LintId::of(types::VEC_BOX),
@@ -1504,7 +1513,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(functions::DOUBLE_MUST_USE),
         LintId::of(functions::MUST_USE_UNIT),
         LintId::of(functions::RESULT_UNIT_ERR),
-        LintId::of(if_let_some_result::IF_LET_SOME_RESULT),
+        LintId::of(if_then_panic::IF_THEN_PANIC),
         LintId::of(inherent_to_string::INHERENT_TO_STRING),
         LintId::of(len_zero::COMPARISON_TO_EMPTY),
         LintId::of(len_zero::LEN_WITHOUT_IS_EMPTY),
@@ -1520,6 +1529,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(manual_map::MANUAL_MAP),
         LintId::of(manual_non_exhaustive::MANUAL_NON_EXHAUSTIVE),
         LintId::of(map_clone::MAP_CLONE),
+        LintId::of(match_result_ok::MATCH_RESULT_OK),
         LintId::of(matches::INFALLIBLE_DESTRUCTURING_MATCH),
         LintId::of(matches::MATCH_LIKE_MATCHES_MACRO),
         LintId::of(matches::MATCH_OVERLAPPING_ARM),
@@ -1564,7 +1574,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(non_copy_const::BORROW_INTERIOR_MUTABLE_CONST),
         LintId::of(non_copy_const::DECLARE_INTERIOR_MUTABLE_CONST),
         LintId::of(non_expressive_names::JUST_UNDERSCORES_AND_DIGITS),
-        LintId::of(non_expressive_names::MANY_SINGLE_CHAR_NAMES),
         LintId::of(ptr::CMP_NULL),
         LintId::of(ptr::PTR_ARG),
         LintId::of(ptr_eq::PTR_EQ),
@@ -1724,7 +1733,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(methods::ZST_OFFSET),
         LintId::of(minmax::MIN_MAX),
         LintId::of(misc::CMP_NAN),
-        LintId::of(misc::FLOAT_CMP),
         LintId::of(misc::MODULO_ONE),
         LintId::of(non_octal_unix_permissions::NON_OCTAL_UNIX_PERMISSIONS),
         LintId::of(open_options::NONSENSICAL_OPEN_OPTIONS),
@@ -1787,7 +1795,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(redundant_clone::REDUNDANT_CLONE),
         LintId::of(slow_vector_initialization::SLOW_VECTOR_INITIALIZATION),
         LintId::of(stable_sort_primitive::STABLE_SORT_PRIMITIVE),
-        LintId::of(types::BOX_VEC),
+        LintId::of(types::BOX_COLLECTION),
         LintId::of(types::REDUNDANT_ALLOCATION),
         LintId::of(vec::USELESS_VEC),
         LintId::of(vec_init_then_push::VEC_INIT_THEN_PUSH),
@@ -1920,6 +1928,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_early_pass(move || Box::new(unnested_or_patterns::UnnestedOrPatterns::new(msrv)));
 
     store.register_late_pass(|| Box::new(size_of_in_element_count::SizeOfInElementCount));
+    store.register_late_pass(|| Box::new(same_name_method::SameNameMethod));
     store.register_late_pass(|| Box::new(map_clone::MapClone));
     store.register_late_pass(|| Box::new(map_err_ignore::MapErrIgnore));
     store.register_late_pass(|| Box::new(shadow::Shadow));
@@ -1952,7 +1961,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| Box::new(empty_enum::EmptyEnum));
     store.register_late_pass(|| Box::new(absurd_extreme_comparisons::AbsurdExtremeComparisons));
     store.register_late_pass(|| Box::new(invalid_upcast_comparisons::InvalidUpcastComparisons));
-    store.register_late_pass(|| Box::new(regex::Regex::default()));
+    store.register_late_pass(|| Box::new(regex::Regex));
     store.register_late_pass(|| Box::new(copies::CopyAndPaste));
     store.register_late_pass(|| Box::new(copy_iterator::CopyIterator));
     store.register_late_pass(|| Box::new(format::UselessFormat));
@@ -1976,7 +1985,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| Box::new(missing_doc::MissingDoc::new()));
     store.register_late_pass(|| Box::new(missing_inline::MissingInline));
     store.register_late_pass(move || Box::new(exhaustive_items::ExhaustiveItems));
-    store.register_late_pass(|| Box::new(if_let_some_result::OkIfLet));
+    store.register_late_pass(|| Box::new(match_result_ok::MatchResultOk));
     store.register_late_pass(|| Box::new(partialeq_ne_impl::PartialEqNeImpl));
     store.register_late_pass(|| Box::new(unused_io_amount::UnusedIoAmount));
     let enum_variant_size_threshold = conf.enum_variant_size_threshold;
@@ -2105,8 +2114,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| Box::new(float_equality_without_abs::FloatEqualityWithoutAbs));
     store.register_late_pass(|| Box::new(semicolon_if_nothing_returned::SemicolonIfNothingReturned));
     store.register_late_pass(|| Box::new(async_yields_async::AsyncYieldsAsync));
-    let disallowed_methods = conf.disallowed_methods.iter().cloned().collect::<FxHashSet<_>>();
-    store.register_late_pass(move || Box::new(disallowed_method::DisallowedMethod::new(&disallowed_methods)));
+    let disallowed_methods = conf.disallowed_methods.clone();
+    store.register_late_pass(move || Box::new(disallowed_method::DisallowedMethod::new(disallowed_methods.clone())));
     store.register_early_pass(|| Box::new(asm_syntax::InlineAsmX86AttSyntax));
     store.register_early_pass(|| Box::new(asm_syntax::InlineAsmX86IntelSyntax));
     store.register_late_pass(|| Box::new(undropped_manually_drops::UndroppedManuallyDrops));
@@ -2131,6 +2140,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| Box::new(strlen_on_c_strings::StrlenOnCStrings));
     store.register_late_pass(move || Box::new(self_named_constructors::SelfNamedConstructors));
     store.register_late_pass(move || Box::new(feature_name::FeatureName));
+    store.register_late_pass(move || Box::new(iter_not_returning_iterator::IterNotReturningIterator));
+    store.register_late_pass(move || Box::new(if_then_panic::IfThenPanic));
 }
 
 #[rustfmt::skip]
@@ -2186,6 +2197,7 @@ pub fn register_renamed(ls: &mut rustc_lint::LintStore) {
     ls.register_renamed("clippy::cyclomatic_complexity", "clippy::cognitive_complexity");
     ls.register_renamed("clippy::const_static_lifetime", "clippy::redundant_static_lifetimes");
     ls.register_renamed("clippy::option_and_then_some", "clippy::bind_instead_of_map");
+    ls.register_renamed("clippy::box_vec", "clippy::box_collection");
     ls.register_renamed("clippy::block_in_if_condition_expr", "clippy::blocks_in_if_conditions");
     ls.register_renamed("clippy::block_in_if_condition_stmt", "clippy::blocks_in_if_conditions");
     ls.register_renamed("clippy::option_map_unwrap_or", "clippy::map_unwrap_or");
@@ -2200,6 +2212,7 @@ pub fn register_renamed(ls: &mut rustc_lint::LintStore) {
     ls.register_renamed("clippy::identity_conversion", "clippy::useless_conversion");
     ls.register_renamed("clippy::zero_width_space", "clippy::invisible_characters");
     ls.register_renamed("clippy::single_char_push_str", "clippy::single_char_add_str");
+    ls.register_renamed("clippy::if_let_some_result", "clippy::match_result_ok");
 
     // uplifted lints
     ls.register_renamed("clippy::invalid_ref", "invalid_value");
diff --git a/src/tools/clippy/clippy_lints/src/loops/for_kv_map.rs b/src/tools/clippy/clippy_lints/src/loops/for_kv_map.rs
index 12ffe7a1364..dd60e460d21 100644
--- a/src/tools/clippy/clippy_lints/src/loops/for_kv_map.rs
+++ b/src/tools/clippy/clippy_lints/src/loops/for_kv_map.rs
@@ -10,12 +10,7 @@ use rustc_middle::ty;
 use rustc_span::sym;
 
 /// Checks for the `FOR_KV_MAP` lint.
-pub(super) fn check<'tcx>(
-    cx: &LateContext<'tcx>,
-    pat: &'tcx Pat<'_>,
-    arg: &'tcx Expr<'_>,
-    body: &'tcx Expr<'_>,
-) {
+pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>, arg: &'tcx Expr<'_>, body: &'tcx Expr<'_>) {
     let pat_span = pat.span;
 
     if let PatKind::Tuple(pat, _) = pat.kind {
diff --git a/src/tools/clippy/clippy_lints/src/loops/while_let_loop.rs b/src/tools/clippy/clippy_lints/src/loops/while_let_loop.rs
index 1848f5b5de2..4dcd5c87722 100644
--- a/src/tools/clippy/clippy_lints/src/loops/while_let_loop.rs
+++ b/src/tools/clippy/clippy_lints/src/loops/while_let_loop.rs
@@ -65,7 +65,7 @@ fn extract_first_expr<'tcx>(block: &Block<'tcx>) -> Option<&'tcx Expr<'tcx>> {
 fn is_simple_break_expr(expr: &Expr<'_>) -> bool {
     match expr.kind {
         ExprKind::Break(dest, ref passed_expr) if dest.label.is_none() && passed_expr.is_none() => true,
-        ExprKind::Block(b, _) => extract_first_expr(b).map_or(false, |subexpr| is_simple_break_expr(subexpr)),
+        ExprKind::Block(b, _) => extract_first_expr(b).map_or(false, is_simple_break_expr),
         _ => false,
     }
 }
diff --git a/src/tools/clippy/clippy_lints/src/loops/while_let_on_iterator.rs b/src/tools/clippy/clippy_lints/src/loops/while_let_on_iterator.rs
index 79527e3bfa9..b390476a664 100644
--- a/src/tools/clippy/clippy_lints/src/loops/while_let_on_iterator.rs
+++ b/src/tools/clippy/clippy_lints/src/loops/while_let_on_iterator.rs
@@ -8,7 +8,7 @@ use clippy_utils::{
 use if_chain::if_chain;
 use rustc_errors::Applicability;
 use rustc_hir::intravisit::{walk_expr, ErasedMap, NestedVisitorMap, Visitor};
-use rustc_hir::{def::Res, Expr, ExprKind, HirId, Local, Mutability, PatKind, QPath, UnOp};
+use rustc_hir::{def::Res, Expr, ExprKind, HirId, Local, PatKind, QPath, UnOp};
 use rustc_lint::LateContext;
 use rustc_span::{symbol::sym, Span, Symbol};
 
@@ -47,13 +47,8 @@ pub(super) fn check(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
     // If the iterator is a field or the iterator is accessed after the loop is complete it needs to be
     // borrowed mutably. TODO: If the struct can be partially moved from and the struct isn't used
     // afterwards a mutable borrow of a field isn't necessary.
-    let ref_mut = if !iter_expr.fields.is_empty() || needs_mutable_borrow(cx, &iter_expr, loop_expr) {
-        if cx.typeck_results().node_type(iter_expr.hir_id).ref_mutability() == Some(Mutability::Mut) {
-            // Reborrow for mutable references. It may not be possible to get a mutable reference here.
-            "&mut *"
-        } else {
-            "&mut "
-        }
+    let by_ref = if !iter_expr.fields.is_empty() || needs_mutable_borrow(cx, &iter_expr, loop_expr) {
+        ".by_ref()"
     } else {
         ""
     };
@@ -65,7 +60,7 @@ pub(super) fn check(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         expr.span.with_hi(scrutinee_expr.span.hi()),
         "this loop could be written as a `for` loop",
         "try",
-        format!("for {} in {}{}", loop_var, ref_mut, iterator),
+        format!("for {} in {}{}", loop_var, iterator, by_ref),
         applicability,
     );
 }
@@ -74,8 +69,6 @@ pub(super) fn check(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
 struct IterExpr {
     /// The span of the whole expression, not just the path and fields stored here.
     span: Span,
-    /// The HIR id of the whole expression, not just the path and fields stored here.
-    hir_id: HirId,
     /// The fields used, in order of child to parent.
     fields: Vec<Symbol>,
     /// The path being used.
@@ -86,14 +79,12 @@ struct IterExpr {
 /// the expression might have side effects.
 fn try_parse_iter_expr(cx: &LateContext<'_>, mut e: &Expr<'_>) -> Option<IterExpr> {
     let span = e.span;
-    let hir_id = e.hir_id;
     let mut fields = Vec::new();
     loop {
         match e.kind {
             ExprKind::Path(ref path) => {
                 break Some(IterExpr {
                     span,
-                    hir_id,
                     fields,
                     path: cx.qpath_res(path, e.hir_id),
                 });
diff --git a/src/tools/clippy/clippy_lints/src/macro_use.rs b/src/tools/clippy/clippy_lints/src/macro_use.rs
index 41e6ad12d05..aff6b3853a4 100644
--- a/src/tools/clippy/clippy_lints/src/macro_use.rs
+++ b/src/tools/clippy/clippy_lints/src/macro_use.rs
@@ -63,29 +63,24 @@ impl MacroUseImports {
     fn push_unique_macro(&mut self, cx: &LateContext<'_>, span: Span) {
         let call_site = span.source_callsite();
         let name = snippet(cx, cx.sess().source_map().span_until_char(call_site, '!'), "_");
-        if let Some(_callee) = span.source_callee() {
-            if !self.collected.contains(&call_site) {
-                let name = if name.contains("::") {
-                    name.split("::").last().unwrap().to_string()
-                } else {
-                    name.to_string()
-                };
+        if span.source_callee().is_some() && !self.collected.contains(&call_site) {
+            let name = if name.contains("::") {
+                name.split("::").last().unwrap().to_string()
+            } else {
+                name.to_string()
+            };
 
-                self.mac_refs.push(MacroRefData::new(name));
-                self.collected.insert(call_site);
-            }
+            self.mac_refs.push(MacroRefData::new(name));
+            self.collected.insert(call_site);
         }
     }
 
     fn push_unique_macro_pat_ty(&mut self, cx: &LateContext<'_>, span: Span) {
         let call_site = span.source_callsite();
         let name = snippet(cx, cx.sess().source_map().span_until_char(call_site, '!'), "_");
-        if let Some(_callee) = span.source_callee() {
-            if !self.collected.contains(&call_site) {
-                self.mac_refs
-                    .push(MacroRefData::new(name.to_string()));
-                self.collected.insert(call_site);
-            }
+        if span.source_callee().is_some() && !self.collected.contains(&call_site) {
+            self.mac_refs.push(MacroRefData::new(name.to_string()));
+            self.collected.insert(call_site);
         }
     }
 }
diff --git a/src/tools/clippy/clippy_lints/src/if_let_some_result.rs b/src/tools/clippy/clippy_lints/src/match_result_ok.rs
index adcd78ed0d4..c7de06f0815 100644
--- a/src/tools/clippy/clippy_lints/src/if_let_some_result.rs
+++ b/src/tools/clippy/clippy_lints/src/match_result_ok.rs
@@ -12,40 +12,51 @@ use rustc_span::sym;
 
 declare_clippy_lint! {
     /// ### What it does
-    ///* Checks for unnecessary `ok()` in if let.
+    /// Checks for unnecessary `ok()` in `while let`.
     ///
     /// ### Why is this bad?
-    /// Calling `ok()` in if let is unnecessary, instead match
+    /// Calling `ok()` in `while let` is unnecessary, instead match
     /// on `Ok(pat)`
     ///
     /// ### Example
     /// ```ignore
-    /// for i in iter {
-    ///     if let Some(value) = i.parse().ok() {
-    ///         vec.push(value)
-    ///     }
+    /// while let Some(value) = iter.next().ok() {
+    ///     vec.push(value)
     /// }
-    /// ```
-    /// Could be written:
     ///
+    /// if let Some(valie) = iter.next().ok() {
+    ///     vec.push(value)
+    /// }
+    /// ```
+    /// Use instead:
     /// ```ignore
-    /// for i in iter {
-    ///     if let Ok(value) = i.parse() {
-    ///         vec.push(value)
-    ///     }
+    /// while let Ok(value) = iter.next() {
+    ///     vec.push(value)
+    /// }
+    ///
+    /// if let Ok(value) = iter.next() {
+    ///        vec.push_value)
     /// }
     /// ```
-    pub IF_LET_SOME_RESULT,
+    pub MATCH_RESULT_OK,
     style,
-    "usage of `ok()` in `if let Some(pat)` statements is unnecessary, match on `Ok(pat)` instead"
+    "usage of `ok()` in `let Some(pat)` statements is unnecessary, match on `Ok(pat)` instead"
 }
 
-declare_lint_pass!(OkIfLet => [IF_LET_SOME_RESULT]);
+declare_lint_pass!(MatchResultOk => [MATCH_RESULT_OK]);
 
-impl<'tcx> LateLintPass<'tcx> for OkIfLet {
+impl<'tcx> LateLintPass<'tcx> for MatchResultOk {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
-        if_chain! { //begin checking variables
-            if let Some(higher::IfLet { let_pat, let_expr, .. }) = higher::IfLet::hir(cx, expr);
+        let (let_pat, let_expr, ifwhile) =
+            if let Some(higher::IfLet { let_pat, let_expr, .. }) = higher::IfLet::hir(cx, expr) {
+                (let_pat, let_expr, "if")
+            } else if let Some(higher::WhileLet { let_pat, let_expr, .. }) = higher::WhileLet::hir(expr) {
+                (let_pat, let_expr, "while")
+            } else {
+                return;
+            };
+
+        if_chain! {
             if let ExprKind::MethodCall(_, ok_span, [ref result_types_0, ..], _) = let_expr.kind; //check is expr.ok() has type Result<T,E>.ok(, _)
             if let PatKind::TupleStruct(QPath::Resolved(_, x), y, _)  = let_pat.kind; //get operation
             if method_chain_args(let_expr, &["ok"]).is_some(); //test to see if using ok() methoduse std::marker::Sized;
@@ -53,17 +64,19 @@ impl<'tcx> LateLintPass<'tcx> for OkIfLet {
             if rustc_hir_pretty::to_string(rustc_hir_pretty::NO_ANN, |s| s.print_path(x, false)) == "Some";
 
             then {
+
                 let mut applicability = Applicability::MachineApplicable;
                 let some_expr_string = snippet_with_applicability(cx, y[0].span, "", &mut applicability);
                 let trimmed_ok = snippet_with_applicability(cx, let_expr.span.until(ok_span), "", &mut applicability);
                 let sugg = format!(
-                    "if let Ok({}) = {}",
+                    "{} let Ok({}) = {}",
+                    ifwhile,
                     some_expr_string,
                     trimmed_ok.trim().trim_end_matches('.'),
                 );
                 span_lint_and_sugg(
                     cx,
-                    IF_LET_SOME_RESULT,
+                    MATCH_RESULT_OK,
                     expr.span.with_hi(let_expr.span.hi()),
                     "matching on `Some` with `ok()` is redundant",
                     &format!("consider matching on `Ok({})` and removing the call to `ok` instead", some_expr_string),
diff --git a/src/tools/clippy/clippy_lints/src/matches.rs b/src/tools/clippy/clippy_lints/src/matches.rs
index 2f1ff567e84..d878fbc35fd 100644
--- a/src/tools/clippy/clippy_lints/src/matches.rs
+++ b/src/tools/clippy/clippy_lints/src/matches.rs
@@ -183,8 +183,8 @@ declare_clippy_lint! {
     /// ```rust
     /// let x = 5;
     /// match x {
-    ///     1...10 => println!("1 ... 10"),
-    ///     5...15 => println!("5 ... 15"),
+    ///     1..=10 => println!("1 ... 10"),
+    ///     5..=15 => println!("5 ... 15"),
     ///     _ => (),
     /// }
     /// ```
diff --git a/src/tools/clippy/clippy_lints/src/methods/manual_split_once.rs b/src/tools/clippy/clippy_lints/src/methods/manual_split_once.rs
index 00167650324..55688677e1d 100644
--- a/src/tools/clippy/clippy_lints/src/methods/manual_split_once.rs
+++ b/src/tools/clippy/clippy_lints/src/methods/manual_split_once.rs
@@ -17,32 +17,25 @@ pub(super) fn check(cx: &LateContext<'_>, method_name: &str, expr: &Expr<'_>, se
     }
 
     let ctxt = expr.span.ctxt();
-    let usage = match parse_iter_usage(cx, ctxt, cx.tcx.hir().parent_iter(expr.hir_id)) {
+    let (method_name, msg, reverse) = if method_name == "splitn" {
+        ("split_once", "manual implementation of `split_once`", false)
+    } else {
+        ("rsplit_once", "manual implementation of `rsplit_once`", true)
+    };
+    let usage = match parse_iter_usage(cx, ctxt, cx.tcx.hir().parent_iter(expr.hir_id), reverse) {
         Some(x) => x,
         None => return,
     };
-    let (method_name, msg) = if method_name == "splitn" {
-        ("split_once", "manual implementation of `split_once`")
-    } else {
-        ("rsplit_once", "manual implementation of `rsplit_once`")
-    };
 
     let mut app = Applicability::MachineApplicable;
     let self_snip = snippet_with_context(cx, self_arg.span, ctxt, "..", &mut app).0;
     let pat_snip = snippet_with_context(cx, pat_arg.span, ctxt, "..", &mut app).0;
 
-    match usage.kind {
+    let sugg = match usage.kind {
         IterUsageKind::NextTuple => {
-            span_lint_and_sugg(
-                cx,
-                MANUAL_SPLIT_ONCE,
-                usage.span,
-                msg,
-                "try this",
-                format!("{}.{}({})", self_snip, method_name, pat_snip),
-                app,
-            );
+            format!("{}.{}({})", self_snip, method_name, pat_snip)
         },
+        IterUsageKind::RNextTuple => format!("{}.{}({}).map(|(x, y)| (y, x))", self_snip, method_name, pat_snip),
         IterUsageKind::Next => {
             let self_deref = {
                 let adjust = cx.typeck_results().expr_adjustments(self_arg);
@@ -58,7 +51,7 @@ pub(super) fn check(cx: &LateContext<'_>, method_name: &str, expr: &Expr<'_>, se
                     "*".repeat(adjust.len() - 2)
                 }
             };
-            let sugg = if usage.unwrap_kind.is_some() {
+            if usage.unwrap_kind.is_some() {
                 format!(
                     "{}.{}({}).map_or({}{}, |x| x.0)",
                     &self_snip, method_name, pat_snip, self_deref, &self_snip
@@ -68,9 +61,7 @@ pub(super) fn check(cx: &LateContext<'_>, method_name: &str, expr: &Expr<'_>, se
                     "Some({}.{}({}).map_or({}{}, |x| x.0))",
                     &self_snip, method_name, pat_snip, self_deref, &self_snip
                 )
-            };
-
-            span_lint_and_sugg(cx, MANUAL_SPLIT_ONCE, usage.span, msg, "try this", sugg, app);
+            }
         },
         IterUsageKind::Second => {
             let access_str = match usage.unwrap_kind {
@@ -78,23 +69,18 @@ pub(super) fn check(cx: &LateContext<'_>, method_name: &str, expr: &Expr<'_>, se
                 Some(UnwrapKind::QuestionMark) => "?.1",
                 None => ".map(|x| x.1)",
             };
-            span_lint_and_sugg(
-                cx,
-                MANUAL_SPLIT_ONCE,
-                usage.span,
-                msg,
-                "try this",
-                format!("{}.{}({}){}", self_snip, method_name, pat_snip, access_str),
-                app,
-            );
+            format!("{}.{}({}){}", self_snip, method_name, pat_snip, access_str)
         },
-    }
+    };
+
+    span_lint_and_sugg(cx, MANUAL_SPLIT_ONCE, usage.span, msg, "try this", sugg, app);
 }
 
 enum IterUsageKind {
     Next,
     Second,
     NextTuple,
+    RNextTuple,
 }
 
 enum UnwrapKind {
@@ -108,10 +94,12 @@ struct IterUsage {
     span: Span,
 }
 
+#[allow(clippy::too_many_lines)]
 fn parse_iter_usage(
     cx: &LateContext<'tcx>,
     ctxt: SyntaxContext,
     mut iter: impl Iterator<Item = (HirId, Node<'tcx>)>,
+    reverse: bool,
 ) -> Option<IterUsage> {
     let (kind, span) = match iter.next() {
         Some((_, Node::Expr(e))) if e.span.ctxt() == ctxt => {
@@ -124,20 +112,30 @@ fn parse_iter_usage(
             let iter_id = cx.tcx.get_diagnostic_item(sym::Iterator)?;
 
             match (&*name.ident.as_str(), args) {
-                ("next", []) if cx.tcx.trait_of_item(did) == Some(iter_id) => (IterUsageKind::Next, e.span),
+                ("next", []) if cx.tcx.trait_of_item(did) == Some(iter_id) => {
+                    if reverse {
+                        (IterUsageKind::Second, e.span)
+                    } else {
+                        (IterUsageKind::Next, e.span)
+                    }
+                },
                 ("next_tuple", []) => {
-                    if_chain! {
+                    return if_chain! {
                         if match_def_path(cx, did, &paths::ITERTOOLS_NEXT_TUPLE);
                         if let ty::Adt(adt_def, subs) = cx.typeck_results().expr_ty(e).kind();
                         if cx.tcx.is_diagnostic_item(sym::option_type, adt_def.did);
                         if let ty::Tuple(subs) = subs.type_at(0).kind();
                         if subs.len() == 2;
                         then {
-                            return Some(IterUsage { kind: IterUsageKind::NextTuple, span: e.span, unwrap_kind: None });
+                            Some(IterUsage {
+                                kind: if reverse { IterUsageKind::RNextTuple } else { IterUsageKind::NextTuple },
+                                span: e.span,
+                                unwrap_kind: None
+                            })
                         } else {
-                            return None;
+                            None
                         }
-                    }
+                    };
                 },
                 ("nth" | "skip", [idx_expr]) if cx.tcx.trait_of_item(did) == Some(iter_id) => {
                     if let Some((Constant::Int(idx), _)) = constant(cx, cx.typeck_results(), idx_expr) {
@@ -158,7 +156,7 @@ fn parse_iter_usage(
                                 }
                             }
                         };
-                        match idx {
+                        match if reverse { idx ^ 1 } else { idx } {
                             0 => (IterUsageKind::Next, span),
                             1 => (IterUsageKind::Second, span),
                             _ => return None,
diff --git a/src/tools/clippy/clippy_lints/src/methods/mod.rs b/src/tools/clippy/clippy_lints/src/methods/mod.rs
index 8a699f13f2e..2025056ac94 100644
--- a/src/tools/clippy/clippy_lints/src/methods/mod.rs
+++ b/src/tools/clippy/clippy_lints/src/methods/mod.rs
@@ -264,6 +264,8 @@ declare_clippy_lint! {
     /// The method signature is controlled by the trait and often `&self` is required for all types that implement the trait
     /// (see e.g. the `std::string::ToString` trait).
     ///
+    /// Clippy allows `Pin<&Self>` and `Pin<&mut Self>` if `&self` and `&mut self` is required.
+    ///
     /// Please find more info here:
     /// https://rust-lang.github.io/api-guidelines/naming.html#ad-hoc-conversions-follow-as_-to_-into_-conventions-c-conv
     ///
diff --git a/src/tools/clippy/clippy_lints/src/misc.rs b/src/tools/clippy/clippy_lints/src/misc.rs
index 538fa4e1678..0f32cd9164e 100644
--- a/src/tools/clippy/clippy_lints/src/misc.rs
+++ b/src/tools/clippy/clippy_lints/src/misc.rs
@@ -113,7 +113,7 @@ declare_clippy_lint! {
     /// if (y - x).abs() > error_margin { }
     /// ```
     pub FLOAT_CMP,
-    correctness,
+    pedantic,
     "using `==` or `!=` on float values instead of comparing difference with an epsilon"
 }
 
diff --git a/src/tools/clippy/clippy_lints/src/mut_key.rs b/src/tools/clippy/clippy_lints/src/mut_key.rs
index 2c7681c45a4..cb17e4dbfd0 100644
--- a/src/tools/clippy/clippy_lints/src/mut_key.rs
+++ b/src/tools/clippy/clippy_lints/src/mut_key.rs
@@ -3,7 +3,7 @@ use clippy_utils::trait_ref_of_method;
 use rustc_hir as hir;
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty::TypeFoldable;
-use rustc_middle::ty::{Adt, Array, RawPtr, Ref, Slice, Tuple, Ty, TypeAndMut};
+use rustc_middle::ty::{Adt, Array, Ref, Slice, Tuple, Ty};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
 use rustc_span::symbol::sym;
@@ -19,10 +19,29 @@ declare_clippy_lint! {
     /// so having types with interior mutability is a bad idea.
     ///
     /// ### Known problems
-    /// It's correct to use a struct, that contains interior mutability
-    /// as a key, when its `Hash` implementation doesn't access any of the interior mutable types.
-    /// However, this lint is unable to recognize this, so it causes a false positive in theses cases.
-    /// The `bytes` crate is a great example of this.
+    ///
+    /// #### False Positives
+    /// It's correct to use a struct that contains interior mutability as a key, when its
+    /// implementation of `Hash` or `Ord` doesn't access any of the interior mutable types.
+    /// However, this lint is unable to recognize this, so it will often cause false positives in
+    /// theses cases.  The `bytes` crate is a great example of this.
+    ///
+    /// #### False Negatives
+    /// For custom `struct`s/`enum`s, this lint is unable to check for interior mutability behind
+    /// indirection.  For example, `struct BadKey<'a>(&'a Cell<usize>)` will be seen as immutable
+    /// and cause a false negative if its implementation of `Hash`/`Ord` accesses the `Cell`.
+    ///
+    /// This lint does check a few cases for indirection.  Firstly, using some standard library
+    /// types (`Option`, `Result`, `Box`, `Rc`, `Arc`, `Vec`, `VecDeque`, `BTreeMap` and
+    /// `BTreeSet`) directly as keys (e.g. in `HashMap<Box<Cell<usize>>, ()>`) **will** trigger the
+    /// lint, because the impls of `Hash`/`Ord` for these types directly call `Hash`/`Ord` on their
+    /// contained type.
+    ///
+    /// Secondly, the implementations of `Hash` and `Ord` for raw pointers (`*const T` or `*mut T`)
+    /// apply only to the **address** of the contained value.  Therefore, interior mutability
+    /// behind raw pointers (e.g. in `HashSet<*mut Cell<usize>>`) can't impact the value of `Hash`
+    /// or `Ord`, and therefore will not trigger this link.  For more info, see issue
+    /// [#6745](https://github.com/rust-lang/rust-clippy/issues/6745).
     ///
     /// ### Example
     /// ```rust
@@ -103,30 +122,52 @@ fn check_sig<'tcx>(cx: &LateContext<'tcx>, item_hir_id: hir::HirId, decl: &hir::
 fn check_ty<'tcx>(cx: &LateContext<'tcx>, span: Span, ty: Ty<'tcx>) {
     let ty = ty.peel_refs();
     if let Adt(def, substs) = ty.kind() {
-        if [sym::hashmap_type, sym::BTreeMap, sym::hashset_type, sym::BTreeMap]
+        let is_keyed_type = [sym::hashmap_type, sym::BTreeMap, sym::hashset_type, sym::BTreeSet]
             .iter()
-            .any(|diag_item| cx.tcx.is_diagnostic_item(*diag_item, def.did))
-            && is_mutable_type(cx, substs.type_at(0), span)
-        {
+            .any(|diag_item| cx.tcx.is_diagnostic_item(*diag_item, def.did));
+        if is_keyed_type && is_interior_mutable_type(cx, substs.type_at(0), span) {
             span_lint(cx, MUTABLE_KEY_TYPE, span, "mutable key type");
         }
     }
 }
 
-fn is_mutable_type<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, span: Span) -> bool {
+/// Determines if a type contains interior mutability which would affect its implementation of
+/// [`Hash`] or [`Ord`].
+fn is_interior_mutable_type<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, span: Span) -> bool {
     match *ty.kind() {
-        RawPtr(TypeAndMut { ty: inner_ty, mutbl }) | Ref(_, inner_ty, mutbl) => {
-            mutbl == hir::Mutability::Mut || is_mutable_type(cx, inner_ty, span)
-        },
-        Slice(inner_ty) => is_mutable_type(cx, inner_ty, span),
+        Ref(_, inner_ty, mutbl) => mutbl == hir::Mutability::Mut || is_interior_mutable_type(cx, inner_ty, span),
+        Slice(inner_ty) => is_interior_mutable_type(cx, inner_ty, span),
         Array(inner_ty, size) => {
-            size.try_eval_usize(cx.tcx, cx.param_env).map_or(true, |u| u != 0) && is_mutable_type(cx, inner_ty, span)
+            size.try_eval_usize(cx.tcx, cx.param_env).map_or(true, |u| u != 0)
+                && is_interior_mutable_type(cx, inner_ty, span)
         },
-        Tuple(..) => ty.tuple_fields().any(|ty| is_mutable_type(cx, ty, span)),
-        Adt(..) => {
-            !ty.has_escaping_bound_vars()
-                && cx.tcx.layout_of(cx.param_env.and(ty)).is_ok()
-                && !ty.is_freeze(cx.tcx.at(span), cx.param_env)
+        Tuple(..) => ty.tuple_fields().any(|ty| is_interior_mutable_type(cx, ty, span)),
+        Adt(def, substs) => {
+            // Special case for collections in `std` who's impl of `Hash` or `Ord` delegates to
+            // that of their type parameters.  Note: we don't include `HashSet` and `HashMap`
+            // because they have no impl for `Hash` or `Ord`.
+            let is_std_collection = [
+                sym::option_type,
+                sym::result_type,
+                sym::LinkedList,
+                sym::vec_type,
+                sym::vecdeque_type,
+                sym::BTreeMap,
+                sym::BTreeSet,
+                sym::Rc,
+                sym::Arc,
+            ]
+            .iter()
+            .any(|diag_item| cx.tcx.is_diagnostic_item(*diag_item, def.did));
+            let is_box = Some(def.did) == cx.tcx.lang_items().owned_box();
+            if is_std_collection || is_box {
+                // The type is mutable if any of its type parameters are
+                substs.types().any(|ty| is_interior_mutable_type(cx, ty, span))
+            } else {
+                !ty.has_escaping_bound_vars()
+                    && cx.tcx.layout_of(cx.param_env.and(ty)).is_ok()
+                    && !ty.is_freeze(cx.tcx.at(span), cx.param_env)
+            }
         },
         _ => false,
     }
diff --git a/src/tools/clippy/clippy_lints/src/needless_borrow.rs b/src/tools/clippy/clippy_lints/src/needless_borrow.rs
index ba8f9446af8..1b2495d764d 100644
--- a/src/tools/clippy/clippy_lints/src/needless_borrow.rs
+++ b/src/tools/clippy/clippy_lints/src/needless_borrow.rs
@@ -104,7 +104,7 @@ impl<'tcx> LateLintPass<'tcx> for NeedlessBorrow {
         if e.span.from_expansion() {
             return;
         }
-        if let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, inner) = e.kind {
+        if let ExprKind::AddrOf(BorrowKind::Ref, mutability, inner) = e.kind {
             if let ty::Ref(_, ty, _) = cx.typeck_results().expr_ty(inner).kind() {
                 for adj3 in cx.typeck_results().expr_adjustments(e).windows(3) {
                     if let [Adjustment {
@@ -116,14 +116,20 @@ impl<'tcx> LateLintPass<'tcx> for NeedlessBorrow {
                         ..
                     }] = *adj3
                     {
+                        let help_msg_ty = if matches!(mutability, Mutability::Not) {
+                            format!("&{}", ty)
+                        } else {
+                            format!("&mut {}", ty)
+                        };
+
                         span_lint_and_then(
                             cx,
                             NEEDLESS_BORROW,
                             e.span,
                             &format!(
-                                "this expression borrows a reference (`&{}`) that is immediately dereferenced \
+                                "this expression borrows a reference (`{}`) that is immediately dereferenced \
                              by the compiler",
-                                ty
+                                help_msg_ty
                             ),
                             |diag| {
                                 if let Some(snippet) = snippet_opt(cx, inner.span) {
diff --git a/src/tools/clippy/clippy_lints/src/non_expressive_names.rs b/src/tools/clippy/clippy_lints/src/non_expressive_names.rs
index 2ffc00b449d..5b254bc8133 100644
--- a/src/tools/clippy/clippy_lints/src/non_expressive_names.rs
+++ b/src/tools/clippy/clippy_lints/src/non_expressive_names.rs
@@ -43,7 +43,7 @@ declare_clippy_lint! {
     /// let (a, b, c, d, e, f, g) = (...);
     /// ```
     pub MANY_SINGLE_CHAR_NAMES,
-    style,
+    pedantic,
     "too many single character bindings"
 }
 
diff --git a/src/tools/clippy/clippy_lints/src/ptr.rs b/src/tools/clippy/clippy_lints/src/ptr.rs
index c0d1f1eb6e6..d696e17d656 100644
--- a/src/tools/clippy/clippy_lints/src/ptr.rs
+++ b/src/tools/clippy/clippy_lints/src/ptr.rs
@@ -372,7 +372,7 @@ fn check_fn(cx: &LateContext<'_>, decl: &FnDecl<'_>, fn_id: HirId, opt_body_id:
             for (_, ref mutbl, ref argspan) in decl
                 .inputs
                 .iter()
-                .filter_map(|ty| get_rptr_lm(ty))
+                .filter_map(get_rptr_lm)
                 .filter(|&(lt, _, _)| lt.name == out.name)
             {
                 if *mutbl == Mutability::Mut {
diff --git a/src/tools/clippy/clippy_lints/src/regex.rs b/src/tools/clippy/clippy_lints/src/regex.rs
index 947c25ac880..5d08aee1e5f 100644
--- a/src/tools/clippy/clippy_lints/src/regex.rs
+++ b/src/tools/clippy/clippy_lints/src/regex.rs
@@ -5,7 +5,7 @@ use if_chain::if_chain;
 use rustc_ast::ast::{LitKind, StrStyle};
 use rustc_hir::{BorrowKind, Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
-use rustc_session::{declare_tool_lint, impl_lint_pass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::{BytePos, Span};
 use std::convert::TryFrom;
 
@@ -51,10 +51,7 @@ declare_clippy_lint! {
     "trivial regular expressions"
 }
 
-#[derive(Clone, Default)]
-pub struct Regex {}
-
-impl_lint_pass!(Regex => [INVALID_REGEX, TRIVIAL_REGEX]);
+declare_lint_pass!(Regex => [INVALID_REGEX, TRIVIAL_REGEX]);
 
 impl<'tcx> LateLintPass<'tcx> for Regex {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
diff --git a/src/tools/clippy/clippy_lints/src/returns.rs b/src/tools/clippy/clippy_lints/src/returns.rs
index 341b5a61631..ae85b7087e7 100644
--- a/src/tools/clippy/clippy_lints/src/returns.rs
+++ b/src/tools/clippy/clippy_lints/src/returns.rs
@@ -11,6 +11,7 @@ use rustc_middle::hir::map::Map;
 use rustc_middle::lint::in_external_macro;
 use rustc_middle::ty::subst::GenericArgKind;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::hygiene::DesugaringKind;
 use rustc_span::source_map::Span;
 use rustc_span::sym;
 
@@ -199,7 +200,9 @@ fn check_final_expr<'tcx>(
                 check_block_return(cx, ifblock);
             }
             if let Some(else_clause) = else_clause_opt {
-                check_final_expr(cx, else_clause, None, RetReplacement::Empty);
+                if expr.span.desugaring_kind() != Some(DesugaringKind::LetElse) {
+                    check_final_expr(cx, else_clause, None, RetReplacement::Empty);
+                }
             }
         },
         // a match expr, check all arms
diff --git a/src/tools/clippy/clippy_lints/src/same_name_method.rs b/src/tools/clippy/clippy_lints/src/same_name_method.rs
new file mode 100644
index 00000000000..014898e6dab
--- /dev/null
+++ b/src/tools/clippy/clippy_lints/src/same_name_method.rs
@@ -0,0 +1,160 @@
+use clippy_utils::diagnostics::span_lint_and_then;
+use rustc_data_structures::fx::FxHashMap;
+use rustc_hir::def::{DefKind, Res};
+use rustc_hir::{Crate, Impl, ItemKind, Node, Path, QPath, TraitRef, TyKind};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty::AssocKind;
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::symbol::Symbol;
+use rustc_span::Span;
+use std::collections::{BTreeMap, BTreeSet};
+
+declare_clippy_lint! {
+    /// ### What it does
+    /// It lints if a struct has two method with same time:
+    /// one from a trait, another not from trait.
+    ///
+    /// ### Why is this bad?
+    /// Confusing.
+    ///
+    /// ### Example
+    /// ```rust
+    /// trait T {
+    ///     fn foo(&self) {}
+    /// }
+    ///
+    /// struct S;
+    ///
+    /// impl T for S {
+    ///     fn foo(&self) {}
+    /// }
+    ///
+    /// impl S {
+    ///     fn foo(&self) {}
+    /// }
+    /// ```
+    pub SAME_NAME_METHOD,
+    restriction,
+    "two method with same name"
+}
+
+declare_lint_pass!(SameNameMethod => [SAME_NAME_METHOD]);
+
+struct ExistingName {
+    impl_methods: BTreeMap<Symbol, Span>,
+    trait_methods: BTreeMap<Symbol, Vec<Span>>,
+}
+
+impl<'tcx> LateLintPass<'tcx> for SameNameMethod {
+    fn check_crate_post(&mut self, cx: &LateContext<'tcx>, krate: &'tcx Crate<'tcx>) {
+        let mut map = FxHashMap::<Res, ExistingName>::default();
+
+        for item in krate.items() {
+            if let ItemKind::Impl(Impl {
+                items,
+                of_trait,
+                self_ty,
+                ..
+            }) = &item.kind
+            {
+                if let TyKind::Path(QPath::Resolved(_, Path { res, .. })) = self_ty.kind {
+                    if !map.contains_key(res) {
+                        map.insert(
+                            *res,
+                            ExistingName {
+                                impl_methods: BTreeMap::new(),
+                                trait_methods: BTreeMap::new(),
+                            },
+                        );
+                    }
+                    let existing_name = map.get_mut(res).unwrap();
+
+                    match of_trait {
+                        Some(trait_ref) => {
+                            let mut methods_in_trait: BTreeSet<Symbol> = if_chain! {
+                                if let Some(Node::TraitRef(TraitRef { path, .. })) =
+                                    cx.tcx.hir().find(trait_ref.hir_ref_id);
+                                if let Res::Def(DefKind::Trait, did) = path.res;
+                                then{
+                                    // FIXME: if
+                                    // `rustc_middle::ty::assoc::AssocItems::items` is public,
+                                    // we can iterate its keys instead of `in_definition_order`,
+                                    // which's more efficient
+                                    cx.tcx
+                                        .associated_items(did)
+                                        .in_definition_order()
+                                        .filter(|assoc_item| {
+                                            matches!(assoc_item.kind, AssocKind::Fn)
+                                        })
+                                        .map(|assoc_item| assoc_item.ident.name)
+                                        .collect()
+                                }else{
+                                    BTreeSet::new()
+                                }
+                            };
+
+                            let mut check_trait_method = |method_name: Symbol, trait_method_span: Span| {
+                                if let Some(impl_span) = existing_name.impl_methods.get(&method_name) {
+                                    span_lint_and_then(
+                                        cx,
+                                        SAME_NAME_METHOD,
+                                        *impl_span,
+                                        "method's name is same to an existing method in a trait",
+                                        |diag| {
+                                            diag.span_note(
+                                                trait_method_span,
+                                                &format!("existing `{}` defined here", method_name),
+                                            );
+                                        },
+                                    );
+                                }
+                                if let Some(v) = existing_name.trait_methods.get_mut(&method_name) {
+                                    v.push(trait_method_span);
+                                } else {
+                                    existing_name.trait_methods.insert(method_name, vec![trait_method_span]);
+                                }
+                            };
+
+                            for impl_item_ref in (*items).iter().filter(|impl_item_ref| {
+                                matches!(impl_item_ref.kind, rustc_hir::AssocItemKind::Fn { .. })
+                            }) {
+                                let method_name = impl_item_ref.ident.name;
+                                methods_in_trait.remove(&method_name);
+                                check_trait_method(method_name, impl_item_ref.span);
+                            }
+
+                            for method_name in methods_in_trait {
+                                check_trait_method(method_name, item.span);
+                            }
+                        },
+                        None => {
+                            for impl_item_ref in (*items).iter().filter(|impl_item_ref| {
+                                matches!(impl_item_ref.kind, rustc_hir::AssocItemKind::Fn { .. })
+                            }) {
+                                let method_name = impl_item_ref.ident.name;
+                                let impl_span = impl_item_ref.span;
+                                if let Some(trait_spans) = existing_name.trait_methods.get(&method_name) {
+                                    span_lint_and_then(
+                                        cx,
+                                        SAME_NAME_METHOD,
+                                        impl_span,
+                                        "method's name is same to an existing method in a trait",
+                                        |diag| {
+                                            // TODO should we `span_note` on every trait?
+                                            // iterate on trait_spans?
+                                            diag.span_note(
+                                                trait_spans[0],
+                                                &format!("existing `{}` defined here", method_name),
+                                            );
+                                        },
+                                    );
+                                }
+                                existing_name.impl_methods.insert(method_name, impl_span);
+                            }
+                        },
+                    }
+                }
+            }
+        }
+    }
+}
diff --git a/src/tools/clippy/clippy_lints/src/types/box_collection.rs b/src/tools/clippy/clippy_lints/src/types/box_collection.rs
new file mode 100644
index 00000000000..b28da29c91c
--- /dev/null
+++ b/src/tools/clippy/clippy_lints/src/types/box_collection.rs
@@ -0,0 +1,50 @@
+use clippy_utils::diagnostics::span_lint_and_help;
+use clippy_utils::is_ty_param_diagnostic_item;
+use rustc_hir::{self as hir, def_id::DefId, QPath};
+use rustc_lint::LateContext;
+use rustc_span::symbol::sym;
+
+use super::BOX_COLLECTION;
+
+pub(super) fn check(cx: &LateContext<'_>, hir_ty: &hir::Ty<'_>, qpath: &QPath<'_>, def_id: DefId) -> bool {
+    if_chain! {
+        if Some(def_id) == cx.tcx.lang_items().owned_box();
+        if let Some(item_type) = get_std_collection(cx, qpath);
+        then {
+            let generic = if item_type == "String" {
+                ""
+            } else {
+                "<..>"
+            };
+            span_lint_and_help(
+                cx,
+                BOX_COLLECTION,
+                hir_ty.span,
+                &format!(
+                    "you seem to be trying to use `Box<{outer}{generic}>`. Consider using just `{outer}{generic}`",
+                    outer=item_type,
+                    generic = generic),
+                None,
+                &format!(
+                    "`{outer}{generic}` is already on the heap, `Box<{outer}{generic}>` makes an extra allocation",
+                    outer=item_type,
+                    generic = generic)
+            );
+            true
+        } else {
+            false
+        }
+    }
+}
+
+fn get_std_collection(cx: &LateContext<'_>, qpath: &QPath<'_>) -> Option<&'static str> {
+    if is_ty_param_diagnostic_item(cx, qpath, sym::vec_type).is_some() {
+        Some("Vec")
+    } else if is_ty_param_diagnostic_item(cx, qpath, sym::string_type).is_some() {
+        Some("String")
+    } else if is_ty_param_diagnostic_item(cx, qpath, sym::hashmap_type).is_some() {
+        Some("HashMap")
+    } else {
+        None
+    }
+}
diff --git a/src/tools/clippy/clippy_lints/src/types/box_vec.rs b/src/tools/clippy/clippy_lints/src/types/box_vec.rs
deleted file mode 100644
index d8b1953457c..00000000000
--- a/src/tools/clippy/clippy_lints/src/types/box_vec.rs
+++ /dev/null
@@ -1,25 +0,0 @@
-use clippy_utils::diagnostics::span_lint_and_help;
-use clippy_utils::is_ty_param_diagnostic_item;
-use rustc_hir::{self as hir, def_id::DefId, QPath};
-use rustc_lint::LateContext;
-use rustc_span::symbol::sym;
-
-use super::BOX_VEC;
-
-pub(super) fn check(cx: &LateContext<'_>, hir_ty: &hir::Ty<'_>, qpath: &QPath<'_>, def_id: DefId) -> bool {
-    if Some(def_id) == cx.tcx.lang_items().owned_box()
-        && is_ty_param_diagnostic_item(cx, qpath, sym::vec_type).is_some()
-    {
-        span_lint_and_help(
-            cx,
-            BOX_VEC,
-            hir_ty.span,
-            "you seem to be trying to use `Box<Vec<T>>`. Consider using just `Vec<T>`",
-            None,
-            "`Vec<T>` is already on the heap, `Box<Vec<T>>` makes an extra allocation",
-        );
-        true
-    } else {
-        false
-    }
-}
diff --git a/src/tools/clippy/clippy_lints/src/types/mod.rs b/src/tools/clippy/clippy_lints/src/types/mod.rs
index 9588de8459c..bbe07db5358 100644
--- a/src/tools/clippy/clippy_lints/src/types/mod.rs
+++ b/src/tools/clippy/clippy_lints/src/types/mod.rs
@@ -1,5 +1,5 @@
 mod borrowed_box;
-mod box_vec;
+mod box_collection;
 mod linked_list;
 mod option_option;
 mod rc_buffer;
@@ -21,12 +21,12 @@ use rustc_span::source_map::Span;
 
 declare_clippy_lint! {
     /// ### What it does
-    /// Checks for use of `Box<Vec<_>>` anywhere in the code.
+    /// Checks for use of `Box<T>` where T is a collection such as Vec anywhere in the code.
     /// Check the [Box documentation](https://doc.rust-lang.org/std/boxed/index.html) for more information.
     ///
     /// ### Why is this bad?
-    /// `Vec` already keeps its contents in a separate area on
-    /// the heap. So if you `Box` it, you just add another level of indirection
+    /// Collections already keeps their contents in a separate area on
+    /// the heap. So if you `Box` them, you just add another level of indirection
     /// without any benefit whatsoever.
     ///
     /// ### Example
@@ -43,7 +43,7 @@ declare_clippy_lint! {
     ///     values: Vec<Foo>,
     /// }
     /// ```
-    pub BOX_VEC,
+    pub BOX_COLLECTION,
     perf,
     "usage of `Box<Vec<T>>`, vector elements are already on the heap"
 }
@@ -298,7 +298,7 @@ pub struct Types {
     avoid_breaking_exported_api: bool,
 }
 
-impl_lint_pass!(Types => [BOX_VEC, VEC_BOX, OPTION_OPTION, LINKEDLIST, BORROWED_BOX, REDUNDANT_ALLOCATION, RC_BUFFER, RC_MUTEX, TYPE_COMPLEXITY]);
+impl_lint_pass!(Types => [BOX_COLLECTION, VEC_BOX, OPTION_OPTION, LINKEDLIST, BORROWED_BOX, REDUNDANT_ALLOCATION, RC_BUFFER, RC_MUTEX, TYPE_COMPLEXITY]);
 
 impl<'tcx> LateLintPass<'tcx> for Types {
     fn check_fn(&mut self, cx: &LateContext<'_>, _: FnKind<'_>, decl: &FnDecl<'_>, _: &Body<'_>, _: Span, id: HirId) {
@@ -447,7 +447,7 @@ impl Types {
                         // in `clippy_lints::utils::conf.rs`
 
                         let mut triggered = false;
-                        triggered |= box_vec::check(cx, hir_ty, qpath, def_id);
+                        triggered |= box_collection::check(cx, hir_ty, qpath, def_id);
                         triggered |= redundant_allocation::check(cx, hir_ty, qpath, def_id);
                         triggered |= rc_buffer::check(cx, hir_ty, qpath, def_id);
                         triggered |= vec_box::check(cx, hir_ty, qpath, def_id, self.vec_box_size_threshold);
diff --git a/src/tools/clippy/clippy_lints/src/utils/conf.rs b/src/tools/clippy/clippy_lints/src/utils/conf.rs
index 8651fa6fcf9..1e0447239be 100644
--- a/src/tools/clippy/clippy_lints/src/utils/conf.rs
+++ b/src/tools/clippy/clippy_lints/src/utils/conf.rs
@@ -15,6 +15,14 @@ pub struct Rename {
     pub rename: String,
 }
 
+/// A single disallowed method, used by the `DISALLOWED_METHOD` lint.
+#[derive(Clone, Debug, Deserialize)]
+#[serde(untagged)]
+pub enum DisallowedMethod {
+    Simple(String),
+    WithReason { path: String, reason: Option<String> },
+}
+
 /// Conf with parse errors
 #[derive(Default)]
 pub struct TryConf {
@@ -128,7 +136,7 @@ macro_rules! define_Conf {
 }
 
 define_Conf! {
-    /// Lint: ENUM_VARIANT_NAMES, LARGE_TYPES_PASSED_BY_VALUE, TRIVIALLY_COPY_PASS_BY_REF, UNNECESSARY_WRAPS, UPPER_CASE_ACRONYMS, WRONG_SELF_CONVENTION, BOX_VEC, REDUNDANT_ALLOCATION, RC_BUFFER, VEC_BOX, OPTION_OPTION, LINKEDLIST, RC_MUTEX.
+    /// Lint: ENUM_VARIANT_NAMES, LARGE_TYPES_PASSED_BY_VALUE, TRIVIALLY_COPY_PASS_BY_REF, UNNECESSARY_WRAPS, UPPER_CASE_ACRONYMS, WRONG_SELF_CONVENTION, BOX_COLLECTION, REDUNDANT_ALLOCATION, RC_BUFFER, VEC_BOX, OPTION_OPTION, LINKEDLIST, RC_MUTEX.
     ///
     /// Suppress lints whenever the suggested change would cause breakage for other crates.
     (avoid_breaking_exported_api: bool = true),
@@ -243,7 +251,7 @@ define_Conf! {
     /// Lint: DISALLOWED_METHOD.
     ///
     /// The list of disallowed methods, written as fully qualified paths.
-    (disallowed_methods: Vec<String> = Vec::new()),
+    (disallowed_methods: Vec<crate::utils::conf::DisallowedMethod> = Vec::new()),
     /// Lint: DISALLOWED_TYPE.
     ///
     /// The list of disallowed types, written as fully qualified paths.
diff --git a/src/tools/clippy/clippy_lints/src/utils/internal_lints.rs b/src/tools/clippy/clippy_lints/src/utils/internal_lints.rs
index 756c33d70c2..3e2a4e9748d 100644
--- a/src/tools/clippy/clippy_lints/src/utils/internal_lints.rs
+++ b/src/tools/clippy/clippy_lints/src/utils/internal_lints.rs
@@ -561,9 +561,7 @@ declare_lint_pass!(ProduceIce => [PRODUCE_ICE]);
 
 impl EarlyLintPass for ProduceIce {
     fn check_fn(&mut self, _: &EarlyContext<'_>, fn_kind: FnKind<'_>, _: Span, _: NodeId) {
-        if is_trigger_fn(fn_kind) {
-            panic!("Would you like some help with that?");
-        }
+        assert!(!is_trigger_fn(fn_kind), "Would you like some help with that?");
     }
 }
 
@@ -894,7 +892,7 @@ impl<'tcx> LateLintPass<'tcx> for InvalidPaths {
                 }).collect();
             if !check_path(cx, &path[..]);
             then {
-                span_lint(cx, CLIPPY_LINTS_INTERNAL, item.span, "invalid path");
+                span_lint(cx, INVALID_PATHS, item.span, "invalid path");
             }
         }
     }
@@ -1224,5 +1222,10 @@ fn if_chain_local_span(cx: &LateContext<'_>, local: &Local<'_>, if_chain_span: S
     let sm = cx.sess().source_map();
     let span = sm.span_extend_to_prev_str(span, "let", false);
     let span = sm.span_extend_to_next_char(span, ';', false);
-    Span::new(span.lo() - BytePos(3), span.hi() + BytePos(1), span.ctxt())
+    Span::new(
+        span.lo() - BytePos(3),
+        span.hi() + BytePos(1),
+        span.ctxt(),
+        span.parent(),
+    )
 }
diff --git a/src/tools/clippy/clippy_lints/src/utils/internal_lints/metadata_collector.rs b/src/tools/clippy/clippy_lints/src/utils/internal_lints/metadata_collector.rs
index 188d0419c39..0d27874b7af 100644
--- a/src/tools/clippy/clippy_lints/src/utils/internal_lints/metadata_collector.rs
+++ b/src/tools/clippy/clippy_lints/src/utils/internal_lints/metadata_collector.rs
@@ -298,6 +298,7 @@ pub struct ClippyConfiguration {
     default: String,
     lints: Vec<String>,
     doc: String,
+    #[allow(dead_code)]
     deprecation_reason: Option<&'static str>,
 }
 
diff --git a/src/tools/clippy/clippy_utils/Cargo.toml b/src/tools/clippy/clippy_utils/Cargo.toml
index 7c24e830e71..e7fca3ae5d4 100644
--- a/src/tools/clippy/clippy_utils/Cargo.toml
+++ b/src/tools/clippy/clippy_utils/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "clippy_utils"
 version = "0.1.57"
-edition = "2018"
+edition = "2021"
 publish = false
 
 [dependencies]
diff --git a/src/tools/clippy/clippy_utils/src/ast_utils.rs b/src/tools/clippy/clippy_utils/src/ast_utils.rs
index 133f6c29f7d..2fa98831c77 100644
--- a/src/tools/clippy/clippy_utils/src/ast_utils.rs
+++ b/src/tools/clippy/clippy_utils/src/ast_utils.rs
@@ -46,15 +46,12 @@ pub fn eq_pat(l: &Pat, r: &Pat) -> bool {
         | (Ref(l, Mutability::Not), Ref(r, Mutability::Not))
         | (Ref(l, Mutability::Mut), Ref(r, Mutability::Mut)) => eq_pat(l, r),
         (Tuple(l), Tuple(r)) | (Slice(l), Slice(r)) => over(l, r, |l, r| eq_pat(l, r)),
-        (Path(lq, lp), Path(rq, rp)) => both(lq, rq, |l, r| eq_qself(l, r)) && eq_path(lp, rp),
+        (Path(lq, lp), Path(rq, rp)) => both(lq, rq, eq_qself) && eq_path(lp, rp),
         (TupleStruct(lqself, lp, lfs), TupleStruct(rqself, rp, rfs)) => {
             eq_maybe_qself(lqself, rqself) && eq_path(lp, rp) && over(lfs, rfs, |l, r| eq_pat(l, r))
         },
         (Struct(lqself, lp, lfs, lr), Struct(rqself, rp, rfs, rr)) => {
-            lr == rr
-                && eq_maybe_qself(lqself, rqself)
-                && eq_path(lp, rp)
-                && unordered_over(lfs, rfs, |lf, rf| eq_field_pat(lf, rf))
+            lr == rr && eq_maybe_qself(lqself, rqself) && eq_path(lp, rp) && unordered_over(lfs, rfs, eq_field_pat)
         },
         (Or(ls), Or(rs)) => unordered_over(ls, rs, |l, r| eq_pat(l, r)),
         (MacCall(l), MacCall(r)) => eq_mac_call(l, r),
@@ -76,7 +73,7 @@ pub fn eq_field_pat(l: &PatField, r: &PatField) -> bool {
     l.is_placeholder == r.is_placeholder
         && eq_id(l.ident, r.ident)
         && eq_pat(&l.pat, &r.pat)
-        && over(&l.attrs, &r.attrs, |l, r| eq_attr(l, r))
+        && over(&l.attrs, &r.attrs, eq_attr)
 }
 
 pub fn eq_qself(l: &QSelf, r: &QSelf) -> bool {
@@ -92,7 +89,7 @@ pub fn eq_maybe_qself(l: &Option<QSelf>, r: &Option<QSelf>) -> bool {
 }
 
 pub fn eq_path(l: &Path, r: &Path) -> bool {
-    over(&l.segments, &r.segments, |l, r| eq_path_seg(l, r))
+    over(&l.segments, &r.segments, eq_path_seg)
 }
 
 pub fn eq_path_seg(l: &PathSegment, r: &PathSegment) -> bool {
@@ -101,9 +98,7 @@ pub fn eq_path_seg(l: &PathSegment, r: &PathSegment) -> bool {
 
 pub fn eq_generic_args(l: &GenericArgs, r: &GenericArgs) -> bool {
     match (l, r) {
-        (GenericArgs::AngleBracketed(l), GenericArgs::AngleBracketed(r)) => {
-            over(&l.args, &r.args, |l, r| eq_angle_arg(l, r))
-        },
+        (GenericArgs::AngleBracketed(l), GenericArgs::AngleBracketed(r)) => over(&l.args, &r.args, eq_angle_arg),
         (GenericArgs::Parenthesized(l), GenericArgs::Parenthesized(r)) => {
             over(&l.inputs, &r.inputs, |l, r| eq_ty(l, r)) && eq_fn_ret_ty(&l.output, &r.output)
         },
@@ -142,7 +137,7 @@ pub fn eq_struct_rest(l: &StructRest, r: &StructRest) -> bool {
 
 pub fn eq_expr(l: &Expr, r: &Expr) -> bool {
     use ExprKind::*;
-    if !over(&l.attrs, &r.attrs, |l, r| eq_attr(l, r)) {
+    if !over(&l.attrs, &r.attrs, eq_attr) {
         return false;
     }
     match (&l.kind, &r.kind) {
@@ -173,20 +168,20 @@ pub fn eq_expr(l: &Expr, r: &Expr) -> bool {
         (Assign(l1, l2, _), Assign(r1, r2, _)) | (Index(l1, l2), Index(r1, r2)) => eq_expr(l1, r1) && eq_expr(l2, r2),
         (AssignOp(lo, lp, lv), AssignOp(ro, rp, rv)) => lo.node == ro.node && eq_expr(lp, rp) && eq_expr(lv, rv),
         (Field(lp, lf), Field(rp, rf)) => eq_id(*lf, *rf) && eq_expr(lp, rp),
-        (Match(ls, la), Match(rs, ra)) => eq_expr(ls, rs) && over(la, ra, |l, r| eq_arm(l, r)),
+        (Match(ls, la), Match(rs, ra)) => eq_expr(ls, rs) && over(la, ra, eq_arm),
         (Closure(lc, la, lm, lf, lb, _), Closure(rc, ra, rm, rf, rb, _)) => {
             lc == rc && la.is_async() == ra.is_async() && lm == rm && eq_fn_decl(lf, rf) && eq_expr(lb, rb)
         },
         (Async(lc, _, lb), Async(rc, _, rb)) => lc == rc && eq_block(lb, rb),
         (Range(lf, lt, ll), Range(rf, rt, rl)) => ll == rl && eq_expr_opt(lf, rf) && eq_expr_opt(lt, rt),
         (AddrOf(lbk, lm, le), AddrOf(rbk, rm, re)) => lbk == rbk && lm == rm && eq_expr(le, re),
-        (Path(lq, lp), Path(rq, rp)) => both(lq, rq, |l, r| eq_qself(l, r)) && eq_path(lp, rp),
+        (Path(lq, lp), Path(rq, rp)) => both(lq, rq, eq_qself) && eq_path(lp, rp),
         (MacCall(l), MacCall(r)) => eq_mac_call(l, r),
         (Struct(lse), Struct(rse)) => {
             eq_maybe_qself(&lse.qself, &rse.qself)
                 && eq_path(&lse.path, &rse.path)
                 && eq_struct_rest(&lse.rest, &rse.rest)
-                && unordered_over(&lse.fields, &rse.fields, |l, r| eq_field(l, r))
+                && unordered_over(&lse.fields, &rse.fields, eq_field)
         },
         _ => false,
     }
@@ -196,7 +191,7 @@ pub fn eq_field(l: &ExprField, r: &ExprField) -> bool {
     l.is_placeholder == r.is_placeholder
         && eq_id(l.ident, r.ident)
         && eq_expr(&l.expr, &r.expr)
-        && over(&l.attrs, &r.attrs, |l, r| eq_attr(l, r))
+        && over(&l.attrs, &r.attrs, eq_attr)
 }
 
 pub fn eq_arm(l: &Arm, r: &Arm) -> bool {
@@ -204,7 +199,7 @@ pub fn eq_arm(l: &Arm, r: &Arm) -> bool {
         && eq_pat(&l.pat, &r.pat)
         && eq_expr(&l.body, &r.body)
         && eq_expr_opt(&l.guard, &r.guard)
-        && over(&l.attrs, &r.attrs, |l, r| eq_attr(l, r))
+        && over(&l.attrs, &r.attrs, eq_attr)
 }
 
 pub fn eq_label(l: &Option<Label>, r: &Option<Label>) -> bool {
@@ -212,7 +207,7 @@ pub fn eq_label(l: &Option<Label>, r: &Option<Label>) -> bool {
 }
 
 pub fn eq_block(l: &Block, r: &Block) -> bool {
-    l.rules == r.rules && over(&l.stmts, &r.stmts, |l, r| eq_stmt(l, r))
+    l.rules == r.rules && over(&l.stmts, &r.stmts, eq_stmt)
 }
 
 pub fn eq_stmt(l: &Stmt, r: &Stmt) -> bool {
@@ -222,13 +217,13 @@ pub fn eq_stmt(l: &Stmt, r: &Stmt) -> bool {
             eq_pat(&l.pat, &r.pat)
                 && both(&l.ty, &r.ty, |l, r| eq_ty(l, r))
                 && eq_local_kind(&l.kind, &r.kind)
-                && over(&l.attrs, &r.attrs, |l, r| eq_attr(l, r))
+                && over(&l.attrs, &r.attrs, eq_attr)
         },
         (Item(l), Item(r)) => eq_item(l, r, eq_item_kind),
         (Expr(l), Expr(r)) | (Semi(l), Semi(r)) => eq_expr(l, r),
         (Empty, Empty) => true,
         (MacCall(l), MacCall(r)) => {
-            l.style == r.style && eq_mac_call(&l.mac, &r.mac) && over(&l.attrs, &r.attrs, |l, r| eq_attr(l, r))
+            l.style == r.style && eq_mac_call(&l.mac, &r.mac) && over(&l.attrs, &r.attrs, eq_attr)
         },
         _ => false,
     }
@@ -245,10 +240,7 @@ pub fn eq_local_kind(l: &LocalKind, r: &LocalKind) -> bool {
 }
 
 pub fn eq_item<K>(l: &Item<K>, r: &Item<K>, mut eq_kind: impl FnMut(&K, &K) -> bool) -> bool {
-    eq_id(l.ident, r.ident)
-        && over(&l.attrs, &r.attrs, |l, r| eq_attr(l, r))
-        && eq_vis(&l.vis, &r.vis)
-        && eq_kind(&l.kind, &r.kind)
+    eq_id(l.ident, r.ident) && over(&l.attrs, &r.attrs, eq_attr) && eq_vis(&l.vis, &r.vis) && eq_kind(&l.kind, &r.kind)
 }
 
 pub fn eq_item_kind(l: &ItemKind, r: &ItemKind) -> bool {
@@ -272,18 +264,15 @@ pub fn eq_item_kind(l: &ItemKind, r: &ItemKind) -> bool {
                 }
         },
         (ForeignMod(l), ForeignMod(r)) => {
-            both(&l.abi, &r.abi, |l, r| eq_str_lit(l, r))
-                && over(&l.items, &r.items, |l, r| eq_item(l, r, eq_foreign_item_kind))
+            both(&l.abi, &r.abi, eq_str_lit) && over(&l.items, &r.items, |l, r| eq_item(l, r, eq_foreign_item_kind))
         },
         (TyAlias(box TyAliasKind(ld, lg, lb, lt)), TyAlias(box TyAliasKind(rd, rg, rb, rt))) => {
             eq_defaultness(*ld, *rd)
                 && eq_generics(lg, rg)
-                && over(lb, rb, |l, r| eq_generic_bound(l, r))
+                && over(lb, rb, eq_generic_bound)
                 && both(lt, rt, |l, r| eq_ty(l, r))
         },
-        (Enum(le, lg), Enum(re, rg)) => {
-            over(&le.variants, &re.variants, |l, r| eq_variant(l, r)) && eq_generics(lg, rg)
-        },
+        (Enum(le, lg), Enum(re, rg)) => over(&le.variants, &re.variants, eq_variant) && eq_generics(lg, rg),
         (Struct(lv, lg), Struct(rv, rg)) | (Union(lv, lg), Union(rv, rg)) => {
             eq_variant_data(lv, rv) && eq_generics(lg, rg)
         },
@@ -291,10 +280,10 @@ pub fn eq_item_kind(l: &ItemKind, r: &ItemKind) -> bool {
             la == ra
                 && matches!(lu, Unsafe::No) == matches!(ru, Unsafe::No)
                 && eq_generics(lg, rg)
-                && over(lb, rb, |l, r| eq_generic_bound(l, r))
+                && over(lb, rb, eq_generic_bound)
                 && over(li, ri, |l, r| eq_item(l, r, eq_assoc_item_kind))
         },
-        (TraitAlias(lg, lb), TraitAlias(rg, rb)) => eq_generics(lg, rg) && over(lb, rb, |l, r| eq_generic_bound(l, r)),
+        (TraitAlias(lg, lb), TraitAlias(rg, rb)) => eq_generics(lg, rg) && over(lb, rb, eq_generic_bound),
         (
             Impl(box ImplKind {
                 unsafety: lu,
@@ -342,7 +331,7 @@ pub fn eq_foreign_item_kind(l: &ForeignItemKind, r: &ForeignItemKind) -> bool {
         (TyAlias(box TyAliasKind(ld, lg, lb, lt)), TyAlias(box TyAliasKind(rd, rg, rb, rt))) => {
             eq_defaultness(*ld, *rd)
                 && eq_generics(lg, rg)
-                && over(lb, rb, |l, r| eq_generic_bound(l, r))
+                && over(lb, rb, eq_generic_bound)
                 && both(lt, rt, |l, r| eq_ty(l, r))
         },
         (MacCall(l), MacCall(r)) => eq_mac_call(l, r),
@@ -360,7 +349,7 @@ pub fn eq_assoc_item_kind(l: &AssocItemKind, r: &AssocItemKind) -> bool {
         (TyAlias(box TyAliasKind(ld, lg, lb, lt)), TyAlias(box TyAliasKind(rd, rg, rb, rt))) => {
             eq_defaultness(*ld, *rd)
                 && eq_generics(lg, rg)
-                && over(lb, rb, |l, r| eq_generic_bound(l, r))
+                && over(lb, rb, eq_generic_bound)
                 && both(lt, rt, |l, r| eq_ty(l, r))
         },
         (MacCall(l), MacCall(r)) => eq_mac_call(l, r),
@@ -370,7 +359,7 @@ pub fn eq_assoc_item_kind(l: &AssocItemKind, r: &AssocItemKind) -> bool {
 
 pub fn eq_variant(l: &Variant, r: &Variant) -> bool {
     l.is_placeholder == r.is_placeholder
-        && over(&l.attrs, &r.attrs, |l, r| eq_attr(l, r))
+        && over(&l.attrs, &r.attrs, eq_attr)
         && eq_vis(&l.vis, &r.vis)
         && eq_id(l.ident, r.ident)
         && eq_variant_data(&l.data, &r.data)
@@ -381,14 +370,14 @@ pub fn eq_variant_data(l: &VariantData, r: &VariantData) -> bool {
     use VariantData::*;
     match (l, r) {
         (Unit(_), Unit(_)) => true,
-        (Struct(l, _), Struct(r, _)) | (Tuple(l, _), Tuple(r, _)) => over(l, r, |l, r| eq_struct_field(l, r)),
+        (Struct(l, _), Struct(r, _)) | (Tuple(l, _), Tuple(r, _)) => over(l, r, eq_struct_field),
         _ => false,
     }
 }
 
 pub fn eq_struct_field(l: &FieldDef, r: &FieldDef) -> bool {
     l.is_placeholder == r.is_placeholder
-        && over(&l.attrs, &r.attrs, |l, r| eq_attr(l, r))
+        && over(&l.attrs, &r.attrs, eq_attr)
         && eq_vis(&l.vis, &r.vis)
         && both(&l.ident, &r.ident, |l, r| eq_id(*l, *r))
         && eq_ty(&l.ty, &r.ty)
@@ -406,7 +395,7 @@ pub fn eq_fn_header(l: &FnHeader, r: &FnHeader) -> bool {
 }
 
 pub fn eq_generics(l: &Generics, r: &Generics) -> bool {
-    over(&l.params, &r.params, |l, r| eq_generic_param(l, r))
+    over(&l.params, &r.params, eq_generic_param)
         && over(&l.where_clause.predicates, &r.where_clause.predicates, |l, r| {
             eq_where_predicate(l, r)
         })
@@ -419,10 +408,10 @@ pub fn eq_where_predicate(l: &WherePredicate, r: &WherePredicate) -> bool {
             over(&l.bound_generic_params, &r.bound_generic_params, |l, r| {
                 eq_generic_param(l, r)
             }) && eq_ty(&l.bounded_ty, &r.bounded_ty)
-                && over(&l.bounds, &r.bounds, |l, r| eq_generic_bound(l, r))
+                && over(&l.bounds, &r.bounds, eq_generic_bound)
         },
         (RegionPredicate(l), RegionPredicate(r)) => {
-            eq_id(l.lifetime.ident, r.lifetime.ident) && over(&l.bounds, &r.bounds, |l, r| eq_generic_bound(l, r))
+            eq_id(l.lifetime.ident, r.lifetime.ident) && over(&l.bounds, &r.bounds, eq_generic_bound)
         },
         (EqPredicate(l), EqPredicate(r)) => eq_ty(&l.lhs_ty, &r.lhs_ty) && eq_ty(&l.rhs_ty, &r.rhs_ty),
         _ => false,
@@ -469,7 +458,7 @@ pub fn eq_fn_decl(l: &FnDecl, r: &FnDecl) -> bool {
             l.is_placeholder == r.is_placeholder
                 && eq_pat(&l.pat, &r.pat)
                 && eq_ty(&l.ty, &r.ty)
-                && over(&l.attrs, &r.attrs, |l, r| eq_attr(l, r))
+                && over(&l.attrs, &r.attrs, eq_attr)
         })
 }
 
@@ -496,13 +485,13 @@ pub fn eq_ty(l: &Ty, r: &Ty) -> bool {
         (BareFn(l), BareFn(r)) => {
             l.unsafety == r.unsafety
                 && eq_ext(&l.ext, &r.ext)
-                && over(&l.generic_params, &r.generic_params, |l, r| eq_generic_param(l, r))
+                && over(&l.generic_params, &r.generic_params, eq_generic_param)
                 && eq_fn_decl(&l.decl, &r.decl)
         },
         (Tup(l), Tup(r)) => over(l, r, |l, r| eq_ty(l, r)),
-        (Path(lq, lp), Path(rq, rp)) => both(lq, rq, |l, r| eq_qself(l, r)) && eq_path(lp, rp),
-        (TraitObject(lg, ls), TraitObject(rg, rs)) => ls == rs && over(lg, rg, |l, r| eq_generic_bound(l, r)),
-        (ImplTrait(_, lg), ImplTrait(_, rg)) => over(lg, rg, |l, r| eq_generic_bound(l, r)),
+        (Path(lq, lp), Path(rq, rp)) => both(lq, rq, eq_qself) && eq_path(lp, rp),
+        (TraitObject(lg, ls), TraitObject(rg, rs)) => ls == rs && over(lg, rg, eq_generic_bound),
+        (ImplTrait(_, lg), ImplTrait(_, rg)) => over(lg, rg, eq_generic_bound),
         (Typeof(l), Typeof(r)) => eq_expr(&l.value, &r.value),
         (MacCall(l), MacCall(r)) => eq_mac_call(l, r),
         _ => false,
@@ -533,7 +522,7 @@ pub fn eq_generic_param(l: &GenericParam, r: &GenericParam) -> bool {
     use GenericParamKind::*;
     l.is_placeholder == r.is_placeholder
         && eq_id(l.ident, r.ident)
-        && over(&l.bounds, &r.bounds, |l, r| eq_generic_bound(l, r))
+        && over(&l.bounds, &r.bounds, eq_generic_bound)
         && match (&l.kind, &r.kind) {
             (Lifetime, Lifetime) => true,
             (Type { default: l }, Type { default: r }) => both(l, r, |l, r| eq_ty(l, r)),
@@ -548,10 +537,10 @@ pub fn eq_generic_param(l: &GenericParam, r: &GenericParam) -> bool {
                     kw_span: _,
                     default: rd,
                 },
-            ) => eq_ty(lt, rt) && both(ld, rd, |ld, rd| eq_anon_const(ld, rd)),
+            ) => eq_ty(lt, rt) && both(ld, rd, eq_anon_const),
             _ => false,
         }
-        && over(&l.attrs, &r.attrs, |l, r| eq_attr(l, r))
+        && over(&l.attrs, &r.attrs, eq_attr)
 }
 
 pub fn eq_generic_bound(l: &GenericBound, r: &GenericBound) -> bool {
@@ -568,7 +557,7 @@ pub fn eq_assoc_constraint(l: &AssocTyConstraint, r: &AssocTyConstraint) -> bool
     eq_id(l.ident, r.ident)
         && match (&l.kind, &r.kind) {
             (Equality { ty: l }, Equality { ty: r }) => eq_ty(l, r),
-            (Bound { bounds: l }, Bound { bounds: r }) => over(l, r, |l, r| eq_generic_bound(l, r)),
+            (Bound { bounds: l }, Bound { bounds: r }) => over(l, r, eq_generic_bound),
             _ => false,
         }
 }
diff --git a/src/tools/clippy/clippy_utils/src/eager_or_lazy.rs b/src/tools/clippy/clippy_utils/src/eager_or_lazy.rs
index 29e2559fc6d..9650294fc7b 100644
--- a/src/tools/clippy/clippy_utils/src/eager_or_lazy.rs
+++ b/src/tools/clippy/clippy_utils/src/eager_or_lazy.rs
@@ -27,10 +27,9 @@ fn identify_some_pure_patterns(expr: &Expr<'_>) -> bool {
     match expr.kind {
         ExprKind::Lit(..) | ExprKind::ConstBlock(..) | ExprKind::Path(..) | ExprKind::Field(..) => true,
         ExprKind::AddrOf(_, _, addr_of_expr) => identify_some_pure_patterns(addr_of_expr),
-        ExprKind::Tup(tup_exprs) => tup_exprs.iter().all(|expr| identify_some_pure_patterns(expr)),
+        ExprKind::Tup(tup_exprs) => tup_exprs.iter().all(identify_some_pure_patterns),
         ExprKind::Struct(_, fields, expr) => {
-            fields.iter().all(|f| identify_some_pure_patterns(f.expr))
-                && expr.map_or(true, |e| identify_some_pure_patterns(e))
+            fields.iter().all(|f| identify_some_pure_patterns(f.expr)) && expr.map_or(true, identify_some_pure_patterns)
         },
         ExprKind::Call(
             &Expr {
@@ -45,7 +44,7 @@ fn identify_some_pure_patterns(expr: &Expr<'_>) -> bool {
                 ..
             },
             args,
-        ) => args.iter().all(|expr| identify_some_pure_patterns(expr)),
+        ) => args.iter().all(identify_some_pure_patterns),
         ExprKind::Block(
             &Block {
                 stmts,
diff --git a/src/tools/clippy/clippy_utils/src/higher.rs b/src/tools/clippy/clippy_utils/src/higher.rs
index e6c06224999..ba4d50bf744 100644
--- a/src/tools/clippy/clippy_utils/src/higher.rs
+++ b/src/tools/clippy/clippy_utils/src/higher.rs
@@ -602,3 +602,33 @@ pub fn is_from_for_desugar(local: &hir::Local<'_>) -> bool {
 
     false
 }
+
+/// A parsed `panic!` expansion
+pub struct PanicExpn<'tcx> {
+    /// Span of `panic!(..)`
+    pub call_site: Span,
+    /// Inner `format_args!` expansion
+    pub format_args: FormatArgsExpn<'tcx>,
+}
+
+impl PanicExpn<'tcx> {
+    /// Parses an expanded `panic!` invocation
+    pub fn parse(expr: &'tcx Expr<'tcx>) -> Option<Self> {
+        if_chain! {
+            if let ExprKind::Block(block, _) = expr.kind;
+            if let Some(init) = block.expr;
+            if let ExprKind::Call(_, [format_args]) = init.kind;
+            let expn_data = expr.span.ctxt().outer_expn_data();
+            if let ExprKind::AddrOf(_, _, format_args) = format_args.kind;
+            if let Some(format_args) = FormatArgsExpn::parse(format_args);
+            then {
+                Some(PanicExpn {
+                    call_site: expn_data.call_site,
+                    format_args,
+                })
+            } else {
+                None
+            }
+        }
+    }
+}
diff --git a/src/tools/clippy/clippy_utils/src/hir_utils.rs b/src/tools/clippy/clippy_utils/src/hir_utils.rs
index 6e9a1de21ee..7438b6eabf9 100644
--- a/src/tools/clippy/clippy_utils/src/hir_utils.rs
+++ b/src/tools/clippy/clippy_utils/src/hir_utils.rs
@@ -540,7 +540,7 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
         std::mem::discriminant(&b.rules).hash(&mut self.s);
     }
 
-    #[allow(clippy::many_single_char_names, clippy::too_many_lines)]
+    #[allow(clippy::too_many_lines)]
     pub fn hash_expr(&mut self, e: &Expr<'_>) {
         let simple_const = self
             .maybe_typeck_results
diff --git a/src/tools/clippy/clippy_utils/src/paths.rs b/src/tools/clippy/clippy_utils/src/paths.rs
index 80be4350c3c..7a8208c12c0 100644
--- a/src/tools/clippy/clippy_utils/src/paths.rs
+++ b/src/tools/clippy/clippy_utils/src/paths.rs
@@ -68,6 +68,7 @@ pub const IO_WRITE: [&str; 3] = ["std", "io", "Write"];
 pub const IPADDR_V4: [&str; 5] = ["std", "net", "ip", "IpAddr", "V4"];
 pub const IPADDR_V6: [&str; 5] = ["std", "net", "ip", "IpAddr", "V6"];
 pub const ITER_REPEAT: [&str; 5] = ["core", "iter", "sources", "repeat", "repeat"];
+#[allow(clippy::invalid_paths)] // internal lints do not know about all external crates
 pub const ITERTOOLS_NEXT_TUPLE: [&str; 3] = ["itertools", "Itertools", "next_tuple"];
 #[cfg(feature = "internal-lints")]
 pub const KW_MODULE: [&str; 3] = ["rustc_span", "symbol", "kw"];
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 e2f2e2008bb..238728f090f 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
@@ -192,9 +192,8 @@ fn check_rvalue(tcx: TyCtxt<'tcx>, body: &Body<'tcx>, def_id: DefId, rvalue: &Rv
                 ))
             }
         },
-        Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf, _) => Ok(()),
+        Rvalue::NullaryOp(NullOp::SizeOf | NullOp::AlignOf, _) | Rvalue::ShallowInitBox(_, _) => Ok(()),
         Rvalue::NullaryOp(NullOp::Box, _) => Err((span, "heap allocations are not allowed in const fn".into())),
-        Rvalue::ShallowInitBox(_, _) => Ok(()),
         Rvalue::UnaryOp(_, operand) => {
             let ty = operand.ty(body, tcx);
             if ty.is_integral() || ty.is_bool() {
diff --git a/src/tools/clippy/lintcheck/src/main.rs b/src/tools/clippy/lintcheck/src/main.rs
index f1e03ba4296..97d3794fb84 100644
--- a/src/tools/clippy/lintcheck/src/main.rs
+++ b/src/tools/clippy/lintcheck/src/main.rs
@@ -15,6 +15,8 @@ use std::{
     env, fmt,
     fs::write,
     path::{Path, PathBuf},
+    thread,
+    time::Duration,
 };
 
 use clap::{App, Arg, ArgMatches};
@@ -109,6 +111,22 @@ impl std::fmt::Display for ClippyWarning {
     }
 }
 
+fn get(path: &str) -> Result<ureq::Response, ureq::Error> {
+    const MAX_RETRIES: u8 = 4;
+    let mut retries = 0;
+    loop {
+        match ureq::get(path).call() {
+            Ok(res) => return Ok(res),
+            Err(e) if retries >= MAX_RETRIES => return Err(e),
+            Err(ureq::Error::Transport(e)) => eprintln!("Error: {}", e),
+            Err(e) => return Err(e),
+        }
+        eprintln!("retrying in {} seconds...", retries);
+        thread::sleep(Duration::from_secs(retries as u64));
+        retries += 1;
+    }
+}
+
 impl CrateSource {
     /// Makes the sources available on the disk for clippy to check.
     /// Clones a git repo and checks out the specified commit or downloads a crate from crates.io or
@@ -129,7 +147,7 @@ impl CrateSource {
                 if !krate_file_path.is_file() {
                     // create a file path to download and write the crate data into
                     let mut krate_dest = std::fs::File::create(&krate_file_path).unwrap();
-                    let mut krate_req = ureq::get(&url).call().unwrap().into_reader();
+                    let mut krate_req = get(&url).unwrap().into_reader();
                     // copy the crate into the file
                     std::io::copy(&mut krate_req, &mut krate_dest).unwrap();
 
diff --git a/src/tools/clippy/rust-toolchain b/src/tools/clippy/rust-toolchain
index 92bde3423a2..660401ff28c 100644
--- a/src/tools/clippy/rust-toolchain
+++ b/src/tools/clippy/rust-toolchain
@@ -1,3 +1,3 @@
 [toolchain]
-channel = "nightly-2021-09-08"
+channel = "nightly-2021-09-28"
 components = ["llvm-tools-preview", "rustc-dev", "rust-src"]
diff --git a/src/tools/clippy/src/main.rs b/src/tools/clippy/src/main.rs
index 7589f42a7b4..7ebdd947893 100644
--- a/src/tools/clippy/src/main.rs
+++ b/src/tools/clippy/src/main.rs
@@ -4,7 +4,6 @@
 
 use rustc_tools_util::VersionInfo;
 use std::env;
-use std::ffi::OsString;
 use std::path::PathBuf;
 use std::process::{self, Command};
 
@@ -14,7 +13,7 @@ Usage:
     cargo clippy [options] [--] [<opts>...]
 
 Common options:
-    --no-deps                Run Clippy only on the given crate, without linting the dependencies 
+    --no-deps                Run Clippy only on the given crate, without linting the dependencies
     --fix                    Automatically apply lint suggestions. This flag implies `--no-deps`
     -h, --help               Print this message
     -V, --version            Print version info and exit
@@ -116,22 +115,6 @@ impl ClippyCmd {
         path
     }
 
-    fn target_dir() -> Option<(&'static str, OsString)> {
-        env::var_os("CLIPPY_DOGFOOD")
-            .map(|_| {
-                env::var_os("CARGO_MANIFEST_DIR").map_or_else(
-                    || std::ffi::OsString::from("clippy_dogfood"),
-                    |d| {
-                        std::path::PathBuf::from(d)
-                            .join("target")
-                            .join("dogfood")
-                            .into_os_string()
-                    },
-                )
-            })
-            .map(|p| ("CARGO_TARGET_DIR", p))
-    }
-
     fn into_std_cmd(self) -> Command {
         let mut cmd = Command::new("cargo");
         let clippy_args: String = self
@@ -141,7 +124,6 @@ impl ClippyCmd {
             .collect();
 
         cmd.env("RUSTC_WORKSPACE_WRAPPER", Self::path())
-            .envs(ClippyCmd::target_dir())
             .env("CLIPPY_ARGS", clippy_args)
             .arg(self.cargo_subcommand)
             .args(&self.args);
diff --git a/src/tools/clippy/tests/cargo/mod.rs b/src/tools/clippy/tests/cargo/mod.rs
index a8f3e3145f6..4dbe71e4b6a 100644
--- a/src/tools/clippy/tests/cargo/mod.rs
+++ b/src/tools/clippy/tests/cargo/mod.rs
@@ -1,25 +1,3 @@
-use std::env;
-use std::lazy::SyncLazy;
-use std::path::PathBuf;
-
-pub static CARGO_TARGET_DIR: SyncLazy<PathBuf> = SyncLazy::new(|| match env::var_os("CARGO_TARGET_DIR") {
-    Some(v) => v.into(),
-    None => env::current_dir().unwrap().join("target"),
-});
-
-pub static TARGET_LIB: SyncLazy<PathBuf> = SyncLazy::new(|| {
-    if let Some(path) = option_env!("TARGET_LIBS") {
-        path.into()
-    } else {
-        let mut dir = CARGO_TARGET_DIR.clone();
-        if let Some(target) = env::var_os("CARGO_BUILD_TARGET") {
-            dir.push(target);
-        }
-        dir.push(env!("PROFILE"));
-        dir
-    }
-});
-
 #[must_use]
 pub fn is_rustc_test_suite() -> bool {
     option_env!("RUSTC_TEST_SUITE").is_some()
diff --git a/src/tools/clippy/tests/compile-test.rs b/src/tools/clippy/tests/compile-test.rs
index c63c47690d5..d7596f6ff0c 100644
--- a/src/tools/clippy/tests/compile-test.rs
+++ b/src/tools/clippy/tests/compile-test.rs
@@ -1,5 +1,4 @@
 #![feature(test)] // compiletest_rs requires this attribute
-#![feature(once_cell)]
 #![cfg_attr(feature = "deny-warnings", deny(warnings))]
 #![warn(rust_2018_idioms, unused_lifetimes)]
 
@@ -46,14 +45,6 @@ extern crate quote;
 #[allow(unused_extern_crates)]
 extern crate syn;
 
-fn host_lib() -> PathBuf {
-    option_env!("HOST_LIBS").map_or(cargo::CARGO_TARGET_DIR.join(env!("PROFILE")), PathBuf::from)
-}
-
-fn clippy_driver_path() -> PathBuf {
-    option_env!("CLIPPY_DRIVER_PATH").map_or(cargo::TARGET_LIB.join("clippy-driver"), PathBuf::from)
-}
-
 /// Produces a string with an `--extern` flag for all UI test crate
 /// dependencies.
 ///
@@ -99,12 +90,14 @@ fn extern_flags() -> String {
         .copied()
         .filter(|n| !crates.contains_key(n))
         .collect();
-    if !not_found.is_empty() {
-        panic!("dependencies not found in depinfo: {:?}", not_found);
-    }
+    assert!(
+        not_found.is_empty(),
+        "dependencies not found in depinfo: {:?}",
+        not_found
+    );
     crates
         .into_iter()
-        .map(|(name, path)| format!("--extern {}={} ", name, path))
+        .map(|(name, path)| format!(" --extern {}={}", name, path))
         .collect()
 }
 
@@ -120,19 +113,29 @@ fn default_config() -> compiletest::Config {
         config.run_lib_path = path.clone();
         config.compile_lib_path = path;
     }
+    let current_exe_path = std::env::current_exe().unwrap();
+    let deps_path = current_exe_path.parent().unwrap();
+    let profile_path = deps_path.parent().unwrap();
 
     // Using `-L dependency={}` enforces that external dependencies are added with `--extern`.
     // This is valuable because a) it allows us to monitor what external dependencies are used
     // and b) it ensures that conflicting rlibs are resolved properly.
+    let host_libs = option_env!("HOST_LIBS")
+        .map(|p| format!(" -L dependency={}", Path::new(p).join("deps").display()))
+        .unwrap_or_default();
     config.target_rustcflags = Some(format!(
-        "--emit=metadata -L dependency={} -L dependency={} -Dwarnings -Zui-testing {}",
-        host_lib().join("deps").display(),
-        cargo::TARGET_LIB.join("deps").display(),
+        "--emit=metadata -Dwarnings -Zui-testing -L dependency={}{}{}",
+        deps_path.display(),
+        host_libs,
         extern_flags(),
     ));
 
-    config.build_base = host_lib().join("test_build_base");
-    config.rustc_path = clippy_driver_path();
+    config.build_base = profile_path.join("test");
+    config.rustc_path = profile_path.join(if cfg!(windows) {
+        "clippy-driver.exe"
+    } else {
+        "clippy-driver"
+    });
     config
 }
 
diff --git a/src/tools/clippy/tests/dogfood.rs b/src/tools/clippy/tests/dogfood.rs
index 54f452172de..a37cdfed126 100644
--- a/src/tools/clippy/tests/dogfood.rs
+++ b/src/tools/clippy/tests/dogfood.rs
@@ -15,7 +15,12 @@ use std::process::Command;
 
 mod cargo;
 
-static CLIPPY_PATH: SyncLazy<PathBuf> = SyncLazy::new(|| cargo::TARGET_LIB.join("cargo-clippy"));
+static CLIPPY_PATH: SyncLazy<PathBuf> = SyncLazy::new(|| {
+    let mut path = std::env::current_exe().unwrap();
+    assert!(path.pop()); // deps
+    path.set_file_name("cargo-clippy");
+    path
+});
 
 #[test]
 fn dogfood_clippy() {
@@ -28,7 +33,6 @@ fn dogfood_clippy() {
     let mut command = Command::new(&*CLIPPY_PATH);
     command
         .current_dir(root_dir)
-        .env("CLIPPY_DOGFOOD", "1")
         .env("CARGO_INCREMENTAL", "0")
         .arg("clippy")
         .arg("--all-targets")
@@ -74,7 +78,6 @@ fn test_no_deps_ignores_path_deps_in_workspaces() {
     // Make sure that with the `--no-deps` argument Clippy does not run on `path_dep`.
     let output = Command::new(&*CLIPPY_PATH)
         .current_dir(&cwd)
-        .env("CLIPPY_DOGFOOD", "1")
         .env("CARGO_INCREMENTAL", "0")
         .arg("clippy")
         .args(&["-p", "subcrate"])
@@ -94,7 +97,6 @@ fn test_no_deps_ignores_path_deps_in_workspaces() {
         // Test that without the `--no-deps` argument, `path_dep` is linted.
         let output = Command::new(&*CLIPPY_PATH)
             .current_dir(&cwd)
-            .env("CLIPPY_DOGFOOD", "1")
             .env("CARGO_INCREMENTAL", "0")
             .arg("clippy")
             .args(&["-p", "subcrate"])
@@ -121,7 +123,6 @@ fn test_no_deps_ignores_path_deps_in_workspaces() {
     let successful_build = || {
         let output = Command::new(&*CLIPPY_PATH)
             .current_dir(&cwd)
-            .env("CLIPPY_DOGFOOD", "1")
             .env("CARGO_INCREMENTAL", "0")
             .arg("clippy")
             .args(&["-p", "subcrate"])
@@ -223,7 +224,6 @@ fn run_clippy_for_project(project: &str) {
 
     command
         .current_dir(root_dir.join(project))
-        .env("CLIPPY_DOGFOOD", "1")
         .env("CARGO_INCREMENTAL", "0")
         .arg("clippy")
         .arg("--all-targets")
diff --git a/src/tools/clippy/tests/integration.rs b/src/tools/clippy/tests/integration.rs
index 7e3eff3c732..c64425fa01a 100644
--- a/src/tools/clippy/tests/integration.rs
+++ b/src/tools/clippy/tests/integration.rs
@@ -74,8 +74,11 @@ fn integration_test() {
         panic!("incompatible crate versions");
     } else if stderr.contains("failed to run `rustc` to learn about target-specific information") {
         panic!("couldn't find librustc_driver, consider setting `LD_LIBRARY_PATH`");
-    } else if stderr.contains("toolchain") && stderr.contains("is not installed") {
-        panic!("missing required toolchain");
+    } else {
+        assert!(
+            !stderr.contains("toolchain") || !stderr.contains("is not installed"),
+            "missing required toolchain"
+        );
     }
 
     match output.status.code() {
diff --git a/src/tools/clippy/tests/ui-internal/invalid_paths.stderr b/src/tools/clippy/tests/ui-internal/invalid_paths.stderr
index bd69d661b71..20aa81b98a0 100644
--- a/src/tools/clippy/tests/ui-internal/invalid_paths.stderr
+++ b/src/tools/clippy/tests/ui-internal/invalid_paths.stderr
@@ -4,7 +4,7 @@ error: invalid path
 LL |     pub const BAD_CRATE_PATH: [&str; 2] = ["bad", "path"];
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: `-D clippy::clippy-lints-internal` implied by `-D warnings`
+   = note: `-D clippy::invalid-paths` implied by `-D warnings`
 
 error: invalid path
   --> $DIR/invalid_paths.rs:20:5
diff --git a/src/tools/clippy/tests/ui-toml/toml_disallowed_method/clippy.toml b/src/tools/clippy/tests/ui-toml/toml_disallowed_method/clippy.toml
index a3245da6825..f1d4a4619c5 100644
--- a/src/tools/clippy/tests/ui-toml/toml_disallowed_method/clippy.toml
+++ b/src/tools/clippy/tests/ui-toml/toml_disallowed_method/clippy.toml
@@ -1,5 +1,8 @@
 disallowed-methods = [
+    # just a string is shorthand for path only
     "std::iter::Iterator::sum",
-    "regex::Regex::is_match",
-    "regex::Regex::new"
+    # can give path and reason with an inline table
+    { path = "regex::Regex::is_match", reason = "no matching allowed" },
+    # can use an inline table but omit reason
+    { path = "regex::Regex::new" },
 ]
diff --git a/src/tools/clippy/tests/ui-toml/toml_disallowed_method/conf_disallowed_method.stderr b/src/tools/clippy/tests/ui-toml/toml_disallowed_method/conf_disallowed_method.stderr
index 2b628c67fa7..38123220a43 100644
--- a/src/tools/clippy/tests/ui-toml/toml_disallowed_method/conf_disallowed_method.stderr
+++ b/src/tools/clippy/tests/ui-toml/toml_disallowed_method/conf_disallowed_method.stderr
@@ -1,4 +1,4 @@
-error: use of a disallowed method `regex::re_unicode::Regex::new`
+error: use of a disallowed method `regex::Regex::new`
   --> $DIR/conf_disallowed_method.rs:7:14
    |
 LL |     let re = Regex::new(r"ab.*c").unwrap();
@@ -6,13 +6,15 @@ LL |     let re = Regex::new(r"ab.*c").unwrap();
    |
    = note: `-D clippy::disallowed-method` implied by `-D warnings`
 
-error: use of a disallowed method `regex::re_unicode::Regex::is_match`
+error: use of a disallowed method `regex::Regex::is_match`
   --> $DIR/conf_disallowed_method.rs:8:5
    |
 LL |     re.is_match("abc");
    |     ^^^^^^^^^^^^^^^^^^
+   |
+   = note: no matching allowed (from clippy.toml)
 
-error: use of a disallowed method `core::iter::traits::iterator::Iterator::sum`
+error: use of a disallowed method `std::iter::Iterator::sum`
   --> $DIR/conf_disallowed_method.rs:11:5
    |
 LL |     a.iter().sum::<i32>();
diff --git a/src/tools/clippy/tests/ui-toml/toml_trivially_copy/test.rs b/src/tools/clippy/tests/ui-toml/toml_trivially_copy/test.rs
index 19019a25416..fb0e226f3aa 100644
--- a/src/tools/clippy/tests/ui-toml/toml_trivially_copy/test.rs
+++ b/src/tools/clippy/tests/ui-toml/toml_trivially_copy/test.rs
@@ -2,7 +2,6 @@
 // normalize-stderr-test "\(limit: \d+ byte\)" -> "(limit: N byte)"
 
 #![deny(clippy::trivially_copy_pass_by_ref)]
-#![allow(clippy::many_single_char_names)]
 
 #[derive(Copy, Clone)]
 struct Foo(u8);
diff --git a/src/tools/clippy/tests/ui-toml/toml_trivially_copy/test.stderr b/src/tools/clippy/tests/ui-toml/toml_trivially_copy/test.stderr
index 912761a8f00..b3ef5928e8e 100644
--- a/src/tools/clippy/tests/ui-toml/toml_trivially_copy/test.stderr
+++ b/src/tools/clippy/tests/ui-toml/toml_trivially_copy/test.stderr
@@ -1,5 +1,5 @@
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/test.rs:15:11
+  --> $DIR/test.rs:14:11
    |
 LL | fn bad(x: &u16, y: &Foo) {}
    |           ^^^^ help: consider passing by value instead: `u16`
@@ -11,7 +11,7 @@ LL | #![deny(clippy::trivially_copy_pass_by_ref)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/test.rs:15:20
+  --> $DIR/test.rs:14:20
    |
 LL | fn bad(x: &u16, y: &Foo) {}
    |                    ^^^^ help: consider passing by value instead: `Foo`
diff --git a/src/tools/clippy/tests/ui/auxiliary/proc_macro_suspicious_else_formatting.rs b/src/tools/clippy/tests/ui/auxiliary/proc_macro_suspicious_else_formatting.rs
new file mode 100644
index 00000000000..26c88489b03
--- /dev/null
+++ b/src/tools/clippy/tests/ui/auxiliary/proc_macro_suspicious_else_formatting.rs
@@ -0,0 +1,75 @@
+// compile-flags: --emit=link
+// no-prefer-dynamic
+
+#![crate_type = "proc-macro"]
+
+extern crate proc_macro;
+use proc_macro::{token_stream, Delimiter, Group, Ident, Span, TokenStream, TokenTree};
+use std::iter::FromIterator;
+
+fn read_ident(iter: &mut token_stream::IntoIter) -> Ident {
+    match iter.next() {
+        Some(TokenTree::Ident(i)) => i,
+        _ => panic!("expected ident"),
+    }
+}
+
+#[proc_macro_derive(DeriveBadSpan)]
+pub fn derive_bad_span(input: TokenStream) -> TokenStream {
+    let mut input = input.into_iter();
+    assert_eq!(read_ident(&mut input).to_string(), "struct");
+    let ident = read_ident(&mut input);
+    let mut tys = match input.next() {
+        Some(TokenTree::Group(g)) if g.delimiter() == Delimiter::Parenthesis => g.stream().into_iter(),
+        _ => panic!(),
+    };
+    let field1 = read_ident(&mut tys);
+    tys.next();
+    let field2 = read_ident(&mut tys);
+
+    <TokenStream as FromIterator<TokenTree>>::from_iter(
+        [
+            Ident::new("impl", Span::call_site()).into(),
+            ident.into(),
+            Group::new(
+                Delimiter::Brace,
+                <TokenStream as FromIterator<TokenTree>>::from_iter(
+                    [
+                        Ident::new("fn", Span::call_site()).into(),
+                        Ident::new("_foo", Span::call_site()).into(),
+                        Group::new(Delimiter::Parenthesis, TokenStream::new()).into(),
+                        Group::new(
+                            Delimiter::Brace,
+                            <TokenStream as FromIterator<TokenTree>>::from_iter(
+                                [
+                                    Ident::new("if", field1.span()).into(),
+                                    Ident::new("true", field1.span()).into(),
+                                    {
+                                        let mut group = Group::new(Delimiter::Brace, TokenStream::new());
+                                        group.set_span(field1.span());
+                                        group.into()
+                                    },
+                                    Ident::new("if", field2.span()).into(),
+                                    Ident::new("true", field2.span()).into(),
+                                    {
+                                        let mut group = Group::new(Delimiter::Brace, TokenStream::new());
+                                        group.set_span(field2.span());
+                                        group.into()
+                                    },
+                                ]
+                                .iter()
+                                .cloned(),
+                            ),
+                        )
+                        .into(),
+                    ]
+                    .iter()
+                    .cloned(),
+                ),
+            )
+            .into(),
+        ]
+        .iter()
+        .cloned(),
+    )
+}
diff --git a/src/tools/clippy/tests/ui/box_vec.rs b/src/tools/clippy/tests/ui/box_collection.rs
index 1d6366972da..e00f061f28a 100644
--- a/src/tools/clippy/tests/ui/box_vec.rs
+++ b/src/tools/clippy/tests/ui/box_collection.rs
@@ -6,6 +6,8 @@
     unused
 )]
 
+use std::collections::HashMap;
+
 macro_rules! boxit {
     ($init:expr, $x:ty) => {
         let _: Box<$x> = Box::new($init);
@@ -15,6 +17,7 @@ macro_rules! boxit {
 fn test_macro() {
     boxit!(Vec::new(), Vec<u8>);
 }
+
 fn test(foo: Box<Vec<bool>>) {}
 
 fn test2(foo: Box<dyn Fn(Vec<u32>)>) {
@@ -22,6 +25,10 @@ fn test2(foo: Box<dyn Fn(Vec<u32>)>) {
     foo(vec![1, 2, 3])
 }
 
+fn test3(foo: Box<String>) {}
+
+fn test4(foo: Box<HashMap<String, String>>) {}
+
 fn test_local_not_linted() {
     let _: Box<Vec<bool>>;
 }
@@ -29,6 +36,7 @@ fn test_local_not_linted() {
 // All of these test should be allowed because they are part of the
 // public api and `avoid_breaking_exported_api` is `false` by default.
 pub fn pub_test(foo: Box<Vec<bool>>) {}
+
 pub fn pub_test_ret() -> Box<Vec<bool>> {
     Box::new(Vec::new())
 }
diff --git a/src/tools/clippy/tests/ui/box_collection.stderr b/src/tools/clippy/tests/ui/box_collection.stderr
new file mode 100644
index 00000000000..6de85d05a99
--- /dev/null
+++ b/src/tools/clippy/tests/ui/box_collection.stderr
@@ -0,0 +1,27 @@
+error: you seem to be trying to use `Box<Vec<..>>`. Consider using just `Vec<..>`
+  --> $DIR/box_collection.rs:21:14
+   |
+LL | fn test(foo: Box<Vec<bool>>) {}
+   |              ^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::box-collection` implied by `-D warnings`
+   = help: `Vec<..>` is already on the heap, `Box<Vec<..>>` makes an extra allocation
+
+error: you seem to be trying to use `Box<String>`. Consider using just `String`
+  --> $DIR/box_collection.rs:28:15
+   |
+LL | fn test3(foo: Box<String>) {}
+   |               ^^^^^^^^^^^
+   |
+   = help: `String` is already on the heap, `Box<String>` makes an extra allocation
+
+error: you seem to be trying to use `Box<HashMap<..>>`. Consider using just `HashMap<..>`
+  --> $DIR/box_collection.rs:30:15
+   |
+LL | fn test4(foo: Box<HashMap<String, String>>) {}
+   |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: `HashMap<..>` is already on the heap, `Box<HashMap<..>>` makes an extra allocation
+
+error: aborting due to 3 previous errors
+
diff --git a/src/tools/clippy/tests/ui/box_vec.stderr b/src/tools/clippy/tests/ui/box_vec.stderr
deleted file mode 100644
index 58c1f13fb87..00000000000
--- a/src/tools/clippy/tests/ui/box_vec.stderr
+++ /dev/null
@@ -1,11 +0,0 @@
-error: you seem to be trying to use `Box<Vec<T>>`. Consider using just `Vec<T>`
-  --> $DIR/box_vec.rs:18:14
-   |
-LL | fn test(foo: Box<Vec<bool>>) {}
-   |              ^^^^^^^^^^^^^^
-   |
-   = note: `-D clippy::box-vec` implied by `-D warnings`
-   = help: `Vec<T>` is already on the heap, `Box<Vec<T>>` makes an extra allocation
-
-error: aborting due to previous error
-
diff --git a/src/tools/clippy/tests/ui/def_id_nocore.rs b/src/tools/clippy/tests/ui/def_id_nocore.rs
index cba7666c2d8..1ed78547a60 100644
--- a/src/tools/clippy/tests/ui/def_id_nocore.rs
+++ b/src/tools/clippy/tests/ui/def_id_nocore.rs
@@ -15,11 +15,12 @@ pub trait Copy {}
 pub unsafe trait Freeze {}
 
 #[lang = "start"]
-#[start]
-fn start(_argc: isize, _argv: *const *const u8) -> isize {
+fn start<T>(_main: fn() -> T, _argc: isize, _argv: *const *const u8) -> isize {
     0
 }
 
+fn main() {}
+
 struct A;
 
 impl A {
diff --git a/src/tools/clippy/tests/ui/def_id_nocore.stderr b/src/tools/clippy/tests/ui/def_id_nocore.stderr
index 702684f6b43..6210d7c6cfd 100644
--- a/src/tools/clippy/tests/ui/def_id_nocore.stderr
+++ b/src/tools/clippy/tests/ui/def_id_nocore.stderr
@@ -1,5 +1,5 @@
 error: methods called `as_*` usually take `self` by reference or `self` by mutable reference
-  --> $DIR/def_id_nocore.rs:26:19
+  --> $DIR/def_id_nocore.rs:27:19
    |
 LL |     pub fn as_ref(self) -> &'static str {
    |                   ^^^^
diff --git a/src/tools/clippy/tests/ui/default_trait_access.fixed b/src/tools/clippy/tests/ui/default_trait_access.fixed
index f1f9c123dc8..9114d8754dc 100644
--- a/src/tools/clippy/tests/ui/default_trait_access.fixed
+++ b/src/tools/clippy/tests/ui/default_trait_access.fixed
@@ -1,6 +1,6 @@
 // run-rustfix
 
-#![allow(unused_imports,dead_code)]
+#![allow(unused_imports, dead_code)]
 #![deny(clippy::default_trait_access)]
 
 use std::default;
diff --git a/src/tools/clippy/tests/ui/default_trait_access.rs b/src/tools/clippy/tests/ui/default_trait_access.rs
index 7f3dfc7f013..8a5f0d6a749 100644
--- a/src/tools/clippy/tests/ui/default_trait_access.rs
+++ b/src/tools/clippy/tests/ui/default_trait_access.rs
@@ -1,6 +1,6 @@
 // run-rustfix
 
-#![allow(unused_imports,dead_code)]
+#![allow(unused_imports, dead_code)]
 #![deny(clippy::default_trait_access)]
 
 use std::default;
diff --git a/src/tools/clippy/tests/ui/deref_addrof.fixed b/src/tools/clippy/tests/ui/deref_addrof.fixed
index 0795900558b..d4832daa689 100644
--- a/src/tools/clippy/tests/ui/deref_addrof.fixed
+++ b/src/tools/clippy/tests/ui/deref_addrof.fixed
@@ -9,7 +9,7 @@ fn get_reference(n: &usize) -> &usize {
     n
 }
 
-#[allow(clippy::many_single_char_names, clippy::double_parens)]
+#[allow(clippy::double_parens)]
 #[allow(unused_variables, unused_parens)]
 fn main() {
     let a = 10;
diff --git a/src/tools/clippy/tests/ui/deref_addrof.rs b/src/tools/clippy/tests/ui/deref_addrof.rs
index 60c4318601b..be7cc669b5b 100644
--- a/src/tools/clippy/tests/ui/deref_addrof.rs
+++ b/src/tools/clippy/tests/ui/deref_addrof.rs
@@ -9,7 +9,7 @@ fn get_reference(n: &usize) -> &usize {
     n
 }
 
-#[allow(clippy::many_single_char_names, clippy::double_parens)]
+#[allow(clippy::double_parens)]
 #[allow(unused_variables, unused_parens)]
 fn main() {
     let a = 10;
diff --git a/src/tools/clippy/tests/ui/derivable_impls.rs b/src/tools/clippy/tests/ui/derivable_impls.rs
index 336a743de72..ebbc0c77e32 100644
--- a/src/tools/clippy/tests/ui/derivable_impls.rs
+++ b/src/tools/clippy/tests/ui/derivable_impls.rs
@@ -167,4 +167,44 @@ impl Default for WithoutSelfParan {
     }
 }
 
+// https://github.com/rust-lang/rust-clippy/issues/7655
+
+pub struct SpecializedImpl2<T> {
+    v: Vec<T>,
+}
+
+impl Default for SpecializedImpl2<String> {
+    fn default() -> Self {
+        Self { v: Vec::new() }
+    }
+}
+
+// https://github.com/rust-lang/rust-clippy/issues/7654
+
+pub struct Color {
+    pub r: u8,
+    pub g: u8,
+    pub b: u8,
+}
+
+/// `#000000`
+impl Default for Color {
+    fn default() -> Self {
+        Color { r: 0, g: 0, b: 0 }
+    }
+}
+
+pub struct Color2 {
+    pub r: u8,
+    pub g: u8,
+    pub b: u8,
+}
+
+impl Default for Color2 {
+    /// `#000000`
+    fn default() -> Self {
+        Self { r: 0, g: 0, b: 0 }
+    }
+}
+
 fn main() {}
diff --git a/src/tools/clippy/tests/ui/eq_op.rs b/src/tools/clippy/tests/ui/eq_op.rs
index 7ab23320db6..707b449f82e 100644
--- a/src/tools/clippy/tests/ui/eq_op.rs
+++ b/src/tools/clippy/tests/ui/eq_op.rs
@@ -2,7 +2,7 @@
 
 #[rustfmt::skip]
 #[warn(clippy::eq_op)]
-#[allow(clippy::identity_op, clippy::double_parens, clippy::many_single_char_names)]
+#[allow(clippy::identity_op, clippy::double_parens)]
 #[allow(clippy::no_effect, unused_variables, clippy::unnecessary_operation, clippy::short_circuit_statement)]
 #[allow(clippy::nonminimal_bool)]
 #[allow(unused)]
diff --git a/src/tools/clippy/tests/ui/eta.fixed b/src/tools/clippy/tests/ui/eta.fixed
index 91b837f9a85..1de79667f55 100644
--- a/src/tools/clippy/tests/ui/eta.fixed
+++ b/src/tools/clippy/tests/ui/eta.fixed
@@ -4,7 +4,6 @@
     unused,
     clippy::no_effect,
     clippy::redundant_closure_call,
-    clippy::many_single_char_names,
     clippy::needless_pass_by_value,
     clippy::option_map_unit_fn
 )]
@@ -14,7 +13,7 @@
     clippy::needless_borrow
 )]
 
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
 
 macro_rules! mac {
     () => {
@@ -30,19 +29,18 @@ macro_rules! closure_mac {
 
 fn main() {
     let a = Some(1u8).map(foo);
-    meta(foo);
     let c = Some(1u8).map(|a| {1+2; foo}(a));
     true.then(|| mac!()); // don't lint function in macro expansion
     Some(1).map(closure_mac!()); // don't lint closure in macro expansion
     let _: Option<Vec<u8>> = true.then(std::vec::Vec::new); // special case vec!
-    let d = Some(1u8).map(|a| foo((|b| foo2(b))(a))); //is adjusted?
-    all(&[1, 2, 3], &2, |x, y| below(x, y)); //is adjusted
+    let d = Some(1u8).map(|a| foo(foo2(a))); //is adjusted?
+    all(&[1, 2, 3], &2, below); //is adjusted
     unsafe {
         Some(1u8).map(|a| unsafe_fn(a)); // unsafe fn
     }
 
     // See #815
-    let e = Some(1u8).map(|a| divergent(a));
+    let e = Some(1u8).map(divergent);
     let e = Some(1u8).map(generic);
     let e = Some(1u8).map(generic);
     // See #515
@@ -90,24 +88,17 @@ impl<'a> std::ops::Deref for TestStruct<'a> {
 fn test_redundant_closures_containing_method_calls() {
     let i = 10;
     let e = Some(TestStruct { some_ref: &i }).map(TestStruct::foo);
-    let e = Some(TestStruct { some_ref: &i }).map(TestStruct::foo);
     let e = Some(TestStruct { some_ref: &i }).map(TestTrait::trait_foo);
     let e = Some(TestStruct { some_ref: &i }).map(|a| a.trait_foo_ref());
-    let e = Some(TestStruct { some_ref: &i }).map(TestTrait::trait_foo);
-    let e = Some(&mut vec![1, 2, 3]).map(std::vec::Vec::clear);
     let e = Some(&mut vec![1, 2, 3]).map(std::vec::Vec::clear);
     unsafe {
         let e = Some(TestStruct { some_ref: &i }).map(|a| a.foo_unsafe());
     }
     let e = Some("str").map(std::string::ToString::to_string);
-    let e = Some("str").map(str::to_string);
-    let e = Some('a').map(char::to_uppercase);
     let e = Some('a').map(char::to_uppercase);
     let e: std::vec::Vec<usize> = vec!['a', 'b', 'c'].iter().map(|c| c.len_utf8()).collect();
     let e: std::vec::Vec<char> = vec!['a', 'b', 'c'].iter().map(char::to_ascii_uppercase).collect();
-    let e: std::vec::Vec<char> = vec!['a', 'b', 'c'].iter().map(char::to_ascii_uppercase).collect();
-    let p = Some(PathBuf::new());
-    let e = p.as_ref().and_then(|s| s.to_str());
+    let e = Some(PathBuf::new()).as_ref().and_then(|s| s.to_str());
     let c = Some(TestStruct { some_ref: &i })
         .as_ref()
         .map(|c| c.to_ascii_uppercase());
@@ -119,10 +110,6 @@ fn test_redundant_closures_containing_method_calls() {
         t.iter().filter(|x| x.trait_foo_ref());
         t.iter().map(|x| x.trait_foo_ref());
     }
-
-    let mut some = Some(|x| x * x);
-    let arr = [Ok(1), Err(2)];
-    let _: Vec<_> = arr.iter().map(|x| x.map_err(|e| some.take().unwrap()(e))).collect();
 }
 
 struct Thunk<T>(Box<dyn FnMut() -> T>);
@@ -145,13 +132,6 @@ fn foobar() {
     thunk.unwrap()
 }
 
-fn meta<F>(f: F)
-where
-    F: Fn(u8),
-{
-    f(1u8)
-}
-
 fn foo(_: u8) {}
 
 fn foo2(_: u8) -> u8 {
@@ -180,7 +160,7 @@ fn generic<T>(_: T) -> u8 {
 }
 
 fn passes_fn_mut(mut x: Box<dyn FnMut()>) {
-    requires_fn_once(|| x());
+    requires_fn_once(x);
 }
 fn requires_fn_once<T: FnOnce()>(_: T) {}
 
@@ -236,3 +216,35 @@ fn mutable_closure_in_loop() {
         Some(1).map(&mut closure);
     }
 }
+
+fn late_bound_lifetimes() {
+    fn take_asref_path<P: AsRef<Path>>(path: P) {}
+
+    fn map_str<F>(thunk: F)
+    where
+        F: FnOnce(&str),
+    {
+    }
+
+    fn map_str_to_path<F>(thunk: F)
+    where
+        F: FnOnce(&str) -> &Path,
+    {
+    }
+    map_str(|s| take_asref_path(s));
+    map_str_to_path(std::convert::AsRef::as_ref);
+}
+
+mod type_param_bound {
+    trait Trait {
+        fn fun();
+    }
+
+    fn take<T: 'static>(_: T) {}
+
+    fn test<X: Trait>() {
+        // don't lint, but it's questionable that rust requires a cast
+        take(|| X::fun());
+        take(X::fun as fn());
+    }
+}
diff --git a/src/tools/clippy/tests/ui/eta.rs b/src/tools/clippy/tests/ui/eta.rs
index 1b53700289d..86abd347baa 100644
--- a/src/tools/clippy/tests/ui/eta.rs
+++ b/src/tools/clippy/tests/ui/eta.rs
@@ -4,7 +4,6 @@
     unused,
     clippy::no_effect,
     clippy::redundant_closure_call,
-    clippy::many_single_char_names,
     clippy::needless_pass_by_value,
     clippy::option_map_unit_fn
 )]
@@ -14,7 +13,7 @@
     clippy::needless_borrow
 )]
 
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
 
 macro_rules! mac {
     () => {
@@ -30,7 +29,6 @@ macro_rules! closure_mac {
 
 fn main() {
     let a = Some(1u8).map(|a| foo(a));
-    meta(|a| foo(a));
     let c = Some(1u8).map(|a| {1+2; foo}(a));
     true.then(|| mac!()); // don't lint function in macro expansion
     Some(1).map(closure_mac!()); // don't lint closure in macro expansion
@@ -90,24 +88,17 @@ impl<'a> std::ops::Deref for TestStruct<'a> {
 fn test_redundant_closures_containing_method_calls() {
     let i = 10;
     let e = Some(TestStruct { some_ref: &i }).map(|a| a.foo());
-    let e = Some(TestStruct { some_ref: &i }).map(TestStruct::foo);
     let e = Some(TestStruct { some_ref: &i }).map(|a| a.trait_foo());
     let e = Some(TestStruct { some_ref: &i }).map(|a| a.trait_foo_ref());
-    let e = Some(TestStruct { some_ref: &i }).map(TestTrait::trait_foo);
     let e = Some(&mut vec![1, 2, 3]).map(|v| v.clear());
-    let e = Some(&mut vec![1, 2, 3]).map(std::vec::Vec::clear);
     unsafe {
         let e = Some(TestStruct { some_ref: &i }).map(|a| a.foo_unsafe());
     }
     let e = Some("str").map(|s| s.to_string());
-    let e = Some("str").map(str::to_string);
     let e = Some('a').map(|s| s.to_uppercase());
-    let e = Some('a').map(char::to_uppercase);
     let e: std::vec::Vec<usize> = vec!['a', 'b', 'c'].iter().map(|c| c.len_utf8()).collect();
     let e: std::vec::Vec<char> = vec!['a', 'b', 'c'].iter().map(|c| c.to_ascii_uppercase()).collect();
-    let e: std::vec::Vec<char> = vec!['a', 'b', 'c'].iter().map(char::to_ascii_uppercase).collect();
-    let p = Some(PathBuf::new());
-    let e = p.as_ref().and_then(|s| s.to_str());
+    let e = Some(PathBuf::new()).as_ref().and_then(|s| s.to_str());
     let c = Some(TestStruct { some_ref: &i })
         .as_ref()
         .map(|c| c.to_ascii_uppercase());
@@ -119,10 +110,6 @@ fn test_redundant_closures_containing_method_calls() {
         t.iter().filter(|x| x.trait_foo_ref());
         t.iter().map(|x| x.trait_foo_ref());
     }
-
-    let mut some = Some(|x| x * x);
-    let arr = [Ok(1), Err(2)];
-    let _: Vec<_> = arr.iter().map(|x| x.map_err(|e| some.take().unwrap()(e))).collect();
 }
 
 struct Thunk<T>(Box<dyn FnMut() -> T>);
@@ -145,13 +132,6 @@ fn foobar() {
     thunk.unwrap()
 }
 
-fn meta<F>(f: F)
-where
-    F: Fn(u8),
-{
-    f(1u8)
-}
-
 fn foo(_: u8) {}
 
 fn foo2(_: u8) -> u8 {
@@ -236,3 +216,35 @@ fn mutable_closure_in_loop() {
         Some(1).map(|n| closure(n));
     }
 }
+
+fn late_bound_lifetimes() {
+    fn take_asref_path<P: AsRef<Path>>(path: P) {}
+
+    fn map_str<F>(thunk: F)
+    where
+        F: FnOnce(&str),
+    {
+    }
+
+    fn map_str_to_path<F>(thunk: F)
+    where
+        F: FnOnce(&str) -> &Path,
+    {
+    }
+    map_str(|s| take_asref_path(s));
+    map_str_to_path(|s| s.as_ref());
+}
+
+mod type_param_bound {
+    trait Trait {
+        fn fun();
+    }
+
+    fn take<T: 'static>(_: T) {}
+
+    fn test<X: Trait>() {
+        // don't lint, but it's questionable that rust requires a cast
+        take(|| X::fun());
+        take(X::fun as fn());
+    }
+}
diff --git a/src/tools/clippy/tests/ui/eta.stderr b/src/tools/clippy/tests/ui/eta.stderr
index 28da8941346..8092f04c3fc 100644
--- a/src/tools/clippy/tests/ui/eta.stderr
+++ b/src/tools/clippy/tests/ui/eta.stderr
@@ -1,5 +1,5 @@
 error: redundant closure
-  --> $DIR/eta.rs:32:27
+  --> $DIR/eta.rs:31:27
    |
 LL |     let a = Some(1u8).map(|a| foo(a));
    |                           ^^^^^^^^^^ help: replace the closure with the function itself: `foo`
@@ -7,19 +7,19 @@ LL |     let a = Some(1u8).map(|a| foo(a));
    = note: `-D clippy::redundant-closure` implied by `-D warnings`
 
 error: redundant closure
-  --> $DIR/eta.rs:33:10
+  --> $DIR/eta.rs:35:40
    |
-LL |     meta(|a| foo(a));
-   |          ^^^^^^^^^^ help: replace the closure with the function itself: `foo`
+LL |     let _: Option<Vec<u8>> = true.then(|| vec![]); // special case vec!
+   |                                        ^^^^^^^^^ help: replace the closure with `Vec::new`: `std::vec::Vec::new`
 
 error: redundant closure
-  --> $DIR/eta.rs:37:40
+  --> $DIR/eta.rs:36:35
    |
-LL |     let _: Option<Vec<u8>> = true.then(|| vec![]); // special case vec!
-   |                                        ^^^^^^^^^ help: replace the closure with `Vec::new`: `std::vec::Vec::new`
+LL |     let d = Some(1u8).map(|a| foo((|b| foo2(b))(a))); //is adjusted?
+   |                                   ^^^^^^^^^^^^^ help: replace the closure with the function itself: `foo2`
 
 error: this expression borrows a reference (`&u8`) that is immediately dereferenced by the compiler
-  --> $DIR/eta.rs:39:21
+  --> $DIR/eta.rs:37:21
    |
 LL |     all(&[1, 2, 3], &&2, |x, y| below(x, y)); //is adjusted
    |                     ^^^ help: change this to: `&2`
@@ -27,13 +27,25 @@ LL |     all(&[1, 2, 3], &&2, |x, y| below(x, y)); //is adjusted
    = note: `-D clippy::needless-borrow` implied by `-D warnings`
 
 error: redundant closure
-  --> $DIR/eta.rs:46:27
+  --> $DIR/eta.rs:37:26
+   |
+LL |     all(&[1, 2, 3], &&2, |x, y| below(x, y)); //is adjusted
+   |                          ^^^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `below`
+
+error: redundant closure
+  --> $DIR/eta.rs:43:27
+   |
+LL |     let e = Some(1u8).map(|a| divergent(a));
+   |                           ^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `divergent`
+
+error: redundant closure
+  --> $DIR/eta.rs:44:27
    |
 LL |     let e = Some(1u8).map(|a| generic(a));
    |                           ^^^^^^^^^^^^^^ help: replace the closure with the function itself: `generic`
 
 error: redundant closure
-  --> $DIR/eta.rs:92:51
+  --> $DIR/eta.rs:90:51
    |
 LL |     let e = Some(TestStruct { some_ref: &i }).map(|a| a.foo());
    |                                                   ^^^^^^^^^^^ help: replace the closure with the method itself: `TestStruct::foo`
@@ -41,70 +53,82 @@ LL |     let e = Some(TestStruct { some_ref: &i }).map(|a| a.foo());
    = note: `-D clippy::redundant-closure-for-method-calls` implied by `-D warnings`
 
 error: redundant closure
-  --> $DIR/eta.rs:94:51
+  --> $DIR/eta.rs:91:51
    |
 LL |     let e = Some(TestStruct { some_ref: &i }).map(|a| a.trait_foo());
    |                                                   ^^^^^^^^^^^^^^^^^ help: replace the closure with the method itself: `TestTrait::trait_foo`
 
 error: redundant closure
-  --> $DIR/eta.rs:97:42
+  --> $DIR/eta.rs:93:42
    |
 LL |     let e = Some(&mut vec![1, 2, 3]).map(|v| v.clear());
    |                                          ^^^^^^^^^^^^^ help: replace the closure with the method itself: `std::vec::Vec::clear`
 
 error: redundant closure
-  --> $DIR/eta.rs:102:29
+  --> $DIR/eta.rs:97:29
    |
 LL |     let e = Some("str").map(|s| s.to_string());
    |                             ^^^^^^^^^^^^^^^^^ help: replace the closure with the method itself: `std::string::ToString::to_string`
 
 error: redundant closure
-  --> $DIR/eta.rs:104:27
+  --> $DIR/eta.rs:98:27
    |
 LL |     let e = Some('a').map(|s| s.to_uppercase());
    |                           ^^^^^^^^^^^^^^^^^^^^ help: replace the closure with the method itself: `char::to_uppercase`
 
 error: redundant closure
-  --> $DIR/eta.rs:107:65
+  --> $DIR/eta.rs:100:65
    |
 LL |     let e: std::vec::Vec<char> = vec!['a', 'b', 'c'].iter().map(|c| c.to_ascii_uppercase()).collect();
    |                                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace the closure with the method itself: `char::to_ascii_uppercase`
 
 error: redundant closure
-  --> $DIR/eta.rs:190:27
+  --> $DIR/eta.rs:163:22
+   |
+LL |     requires_fn_once(|| x());
+   |                      ^^^^^^ help: replace the closure with the function itself: `x`
+
+error: redundant closure
+  --> $DIR/eta.rs:170:27
    |
 LL |     let a = Some(1u8).map(|a| foo_ptr(a));
    |                           ^^^^^^^^^^^^^^ help: replace the closure with the function itself: `foo_ptr`
 
 error: redundant closure
-  --> $DIR/eta.rs:195:27
+  --> $DIR/eta.rs:175:27
    |
 LL |     let a = Some(1u8).map(|a| closure(a));
    |                           ^^^^^^^^^^^^^^ help: replace the closure with the function itself: `closure`
 
 error: redundant closure
-  --> $DIR/eta.rs:227:28
+  --> $DIR/eta.rs:207:28
    |
 LL |     x.into_iter().for_each(|x| add_to_res(x));
    |                            ^^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `&mut add_to_res`
 
 error: redundant closure
-  --> $DIR/eta.rs:228:28
+  --> $DIR/eta.rs:208:28
    |
 LL |     y.into_iter().for_each(|x| add_to_res(x));
    |                            ^^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `&mut add_to_res`
 
 error: redundant closure
-  --> $DIR/eta.rs:229:28
+  --> $DIR/eta.rs:209:28
    |
 LL |     z.into_iter().for_each(|x| add_to_res(x));
    |                            ^^^^^^^^^^^^^^^^^ help: replace the closure with the function itself: `add_to_res`
 
 error: redundant closure
-  --> $DIR/eta.rs:236:21
+  --> $DIR/eta.rs:216:21
    |
 LL |         Some(1).map(|n| closure(n));
    |                     ^^^^^^^^^^^^^^ help: replace the closure with the function itself: `&mut closure`
 
-error: aborting due to 17 previous errors
+error: redundant closure
+  --> $DIR/eta.rs:235:21
+   |
+LL |     map_str_to_path(|s| s.as_ref());
+   |                     ^^^^^^^^^^^^^^ help: replace the closure with the method itself: `std::convert::AsRef::as_ref`
+
+error: aborting due to 21 previous errors
 
diff --git a/src/tools/clippy/tests/ui/eval_order_dependence.rs b/src/tools/clippy/tests/ui/eval_order_dependence.rs
index d742856bc41..8e6a32b7be3 100644
--- a/src/tools/clippy/tests/ui/eval_order_dependence.rs
+++ b/src/tools/clippy/tests/ui/eval_order_dependence.rs
@@ -4,7 +4,6 @@
 #[allow(
     unused_assignments,
     unused_variables,
-    clippy::many_single_char_names,
     clippy::no_effect,
     dead_code,
     clippy::blacklisted_name
diff --git a/src/tools/clippy/tests/ui/eval_order_dependence.stderr b/src/tools/clippy/tests/ui/eval_order_dependence.stderr
index 35eb85e95a3..4f611e308e1 100644
--- a/src/tools/clippy/tests/ui/eval_order_dependence.stderr
+++ b/src/tools/clippy/tests/ui/eval_order_dependence.stderr
@@ -1,48 +1,48 @@
 error: unsequenced read of `x`
-  --> $DIR/eval_order_dependence.rs:17:9
+  --> $DIR/eval_order_dependence.rs:16:9
    |
 LL |     } + x;
    |         ^
    |
    = note: `-D clippy::eval-order-dependence` implied by `-D warnings`
 note: whether read occurs before this write depends on evaluation order
-  --> $DIR/eval_order_dependence.rs:15:9
+  --> $DIR/eval_order_dependence.rs:14:9
    |
 LL |         x = 1;
    |         ^^^^^
 
 error: unsequenced read of `x`
-  --> $DIR/eval_order_dependence.rs:20:5
+  --> $DIR/eval_order_dependence.rs:19:5
    |
 LL |     x += {
    |     ^
    |
 note: whether read occurs before this write depends on evaluation order
-  --> $DIR/eval_order_dependence.rs:21:9
+  --> $DIR/eval_order_dependence.rs:20:9
    |
 LL |         x = 20;
    |         ^^^^^^
 
 error: unsequenced read of `x`
-  --> $DIR/eval_order_dependence.rs:33:12
+  --> $DIR/eval_order_dependence.rs:32:12
    |
 LL |         a: x,
    |            ^
    |
 note: whether read occurs before this write depends on evaluation order
-  --> $DIR/eval_order_dependence.rs:35:13
+  --> $DIR/eval_order_dependence.rs:34:13
    |
 LL |             x = 6;
    |             ^^^^^
 
 error: unsequenced read of `x`
-  --> $DIR/eval_order_dependence.rs:42:9
+  --> $DIR/eval_order_dependence.rs:41:9
    |
 LL |         x += {
    |         ^
    |
 note: whether read occurs before this write depends on evaluation order
-  --> $DIR/eval_order_dependence.rs:43:13
+  --> $DIR/eval_order_dependence.rs:42:13
    |
 LL |             x = 20;
    |             ^^^^^^
diff --git a/src/tools/clippy/tests/ui/excessive_precision.fixed b/src/tools/clippy/tests/ui/excessive_precision.fixed
index bf0325fec79..90376620a9f 100644
--- a/src/tools/clippy/tests/ui/excessive_precision.fixed
+++ b/src/tools/clippy/tests/ui/excessive_precision.fixed
@@ -17,8 +17,8 @@ fn main() {
     const BAD32_3: f32 = 0.1;
     const BAD32_EDGE: f32 = 1.000_001;
 
-    const BAD64_1: f64 = 0.123_456_789_012_345_66_f64;
-    const BAD64_2: f64 = 0.123_456_789_012_345_66;
+    const BAD64_1: f64 = 0.123_456_789_012_345_67f64;
+    const BAD64_2: f64 = 0.123_456_789_012_345_67;
     const BAD64_3: f64 = 0.1;
 
     // Literal as param
@@ -37,9 +37,9 @@ fn main() {
     let bad32_suf: f32 = 1.123_456_8_f32;
     let bad32_inf = 1.123_456_8_f32;
 
-    let bad64: f64 = 0.123_456_789_012_345_66;
-    let bad64_suf: f64 = 0.123_456_789_012_345_66_f64;
-    let bad64_inf = 0.123_456_789_012_345_66;
+    let bad64: f64 = 0.123_456_789_012_345_67;
+    let bad64_suf: f64 = 0.123_456_789_012_345_67f64;
+    let bad64_inf = 0.123_456_789_012_345_67;
 
     // Vectors
     let good_vec32: Vec<f32> = vec![0.123_456];
diff --git a/src/tools/clippy/tests/ui/excessive_precision.stderr b/src/tools/clippy/tests/ui/excessive_precision.stderr
index 599773f2f70..e59c20c30b4 100644
--- a/src/tools/clippy/tests/ui/excessive_precision.stderr
+++ b/src/tools/clippy/tests/ui/excessive_precision.stderr
@@ -25,18 +25,6 @@ LL |     const BAD32_EDGE: f32 = 1.000_000_9;
    |                             ^^^^^^^^^^^ help: consider changing the type or truncating it to: `1.000_001`
 
 error: float has excessive precision
-  --> $DIR/excessive_precision.rs:20:26
-   |
-LL |     const BAD64_1: f64 = 0.123_456_789_012_345_67f64;
-   |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `0.123_456_789_012_345_66_f64`
-
-error: float has excessive precision
-  --> $DIR/excessive_precision.rs:21:26
-   |
-LL |     const BAD64_2: f64 = 0.123_456_789_012_345_67;
-   |                          ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `0.123_456_789_012_345_66`
-
-error: float has excessive precision
   --> $DIR/excessive_precision.rs:22:26
    |
 LL |     const BAD64_3: f64 = 0.100_000_000_000_000_000_1;
@@ -67,24 +55,6 @@ LL |     let bad32_inf = 1.123_456_789_f32;
    |                     ^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `1.123_456_8_f32`
 
 error: float has excessive precision
-  --> $DIR/excessive_precision.rs:40:22
-   |
-LL |     let bad64: f64 = 0.123_456_789_012_345_67;
-   |                      ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `0.123_456_789_012_345_66`
-
-error: float has excessive precision
-  --> $DIR/excessive_precision.rs:41:26
-   |
-LL |     let bad64_suf: f64 = 0.123_456_789_012_345_67f64;
-   |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `0.123_456_789_012_345_66_f64`
-
-error: float has excessive precision
-  --> $DIR/excessive_precision.rs:42:21
-   |
-LL |     let bad64_inf = 0.123_456_789_012_345_67;
-   |                     ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `0.123_456_789_012_345_66`
-
-error: float has excessive precision
   --> $DIR/excessive_precision.rs:48:36
    |
 LL |     let bad_vec32: Vec<f32> = vec![0.123_456_789];
@@ -108,5 +78,5 @@ error: float has excessive precision
 LL |     let bad_bige32: f32 = 1.123_456_788_888E-10;
    |                           ^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `1.123_456_8E-10`
 
-error: aborting due to 18 previous errors
+error: aborting due to 13 previous errors
 
diff --git a/src/tools/clippy/tests/ui/explicit_deref_methods.fixed b/src/tools/clippy/tests/ui/explicit_deref_methods.fixed
index 51d0468e47c..48e2aae75d0 100644
--- a/src/tools/clippy/tests/ui/explicit_deref_methods.fixed
+++ b/src/tools/clippy/tests/ui/explicit_deref_methods.fixed
@@ -1,6 +1,6 @@
 // run-rustfix
 
-#![allow(unused_variables, clippy::many_single_char_names, clippy::clone_double_ref)]
+#![allow(unused_variables, clippy::clone_double_ref)]
 #![warn(clippy::explicit_deref_methods)]
 
 use std::ops::{Deref, DerefMut};
diff --git a/src/tools/clippy/tests/ui/explicit_deref_methods.rs b/src/tools/clippy/tests/ui/explicit_deref_methods.rs
index 680664bd4f6..d8c8c0c5ca3 100644
--- a/src/tools/clippy/tests/ui/explicit_deref_methods.rs
+++ b/src/tools/clippy/tests/ui/explicit_deref_methods.rs
@@ -1,6 +1,6 @@
 // run-rustfix
 
-#![allow(unused_variables, clippy::many_single_char_names, clippy::clone_double_ref)]
+#![allow(unused_variables, clippy::clone_double_ref)]
 #![warn(clippy::explicit_deref_methods)]
 
 use std::ops::{Deref, DerefMut};
diff --git a/src/tools/clippy/tests/ui/fallible_impl_from.rs b/src/tools/clippy/tests/ui/fallible_impl_from.rs
index 5d5af4e4632..495cd97e05e 100644
--- a/src/tools/clippy/tests/ui/fallible_impl_from.rs
+++ b/src/tools/clippy/tests/ui/fallible_impl_from.rs
@@ -1,4 +1,5 @@
 #![deny(clippy::fallible_impl_from)]
+#![allow(clippy::if_then_panic)]
 
 // docs example
 struct Foo(i32);
diff --git a/src/tools/clippy/tests/ui/fallible_impl_from.stderr b/src/tools/clippy/tests/ui/fallible_impl_from.stderr
index 64c8ea85727..8b8054586e6 100644
--- a/src/tools/clippy/tests/ui/fallible_impl_from.stderr
+++ b/src/tools/clippy/tests/ui/fallible_impl_from.stderr
@@ -1,5 +1,5 @@
 error: consider implementing `TryFrom` instead
-  --> $DIR/fallible_impl_from.rs:5:1
+  --> $DIR/fallible_impl_from.rs:6:1
    |
 LL | / impl From<String> for Foo {
 LL | |     fn from(s: String) -> Self {
@@ -15,13 +15,13 @@ LL | #![deny(clippy::fallible_impl_from)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^
    = help: `From` is intended for infallible conversions only. Use `TryFrom` if there's a possibility for the conversion to fail
 note: potential failure(s)
-  --> $DIR/fallible_impl_from.rs:7:13
+  --> $DIR/fallible_impl_from.rs:8:13
    |
 LL |         Foo(s.parse().unwrap())
    |             ^^^^^^^^^^^^^^^^^^
 
 error: consider implementing `TryFrom` instead
-  --> $DIR/fallible_impl_from.rs:26:1
+  --> $DIR/fallible_impl_from.rs:27:1
    |
 LL | / impl From<usize> for Invalid {
 LL | |     fn from(i: usize) -> Invalid {
@@ -34,14 +34,14 @@ LL | | }
    |
    = help: `From` is intended for infallible conversions only. Use `TryFrom` if there's a possibility for the conversion to fail
 note: potential failure(s)
-  --> $DIR/fallible_impl_from.rs:29:13
+  --> $DIR/fallible_impl_from.rs:30:13
    |
 LL |             panic!();
    |             ^^^^^^^^^
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: consider implementing `TryFrom` instead
-  --> $DIR/fallible_impl_from.rs:35:1
+  --> $DIR/fallible_impl_from.rs:36:1
    |
 LL | / impl From<Option<String>> for Invalid {
 LL | |     fn from(s: Option<String>) -> Invalid {
@@ -54,7 +54,7 @@ LL | | }
    |
    = help: `From` is intended for infallible conversions only. Use `TryFrom` if there's a possibility for the conversion to fail
 note: potential failure(s)
-  --> $DIR/fallible_impl_from.rs:37:17
+  --> $DIR/fallible_impl_from.rs:38:17
    |
 LL |         let s = s.unwrap();
    |                 ^^^^^^^^^^
@@ -68,7 +68,7 @@ LL |             panic!("{:?}", s);
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: consider implementing `TryFrom` instead
-  --> $DIR/fallible_impl_from.rs:53:1
+  --> $DIR/fallible_impl_from.rs:54:1
    |
 LL | / impl<'a> From<&'a mut <Box<u32> as ProjStrTrait>::ProjString> for Invalid {
 LL | |     fn from(s: &'a mut <Box<u32> as ProjStrTrait>::ProjString) -> Invalid {
@@ -81,7 +81,7 @@ LL | | }
    |
    = help: `From` is intended for infallible conversions only. Use `TryFrom` if there's a possibility for the conversion to fail
 note: potential failure(s)
-  --> $DIR/fallible_impl_from.rs:55:12
+  --> $DIR/fallible_impl_from.rs:56:12
    |
 LL |         if s.parse::<u32>().ok().unwrap() != 42 {
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/src/tools/clippy/tests/ui/float_cmp.rs b/src/tools/clippy/tests/ui/float_cmp.rs
index ad5d1a09c03..a34458b9419 100644
--- a/src/tools/clippy/tests/ui/float_cmp.rs
+++ b/src/tools/clippy/tests/ui/float_cmp.rs
@@ -4,8 +4,7 @@
     clippy::no_effect,
     clippy::op_ref,
     clippy::unnecessary_operation,
-    clippy::cast_lossless,
-    clippy::many_single_char_names
+    clippy::cast_lossless
 )]
 
 use std::ops::Add;
diff --git a/src/tools/clippy/tests/ui/float_cmp.stderr b/src/tools/clippy/tests/ui/float_cmp.stderr
index cb5b68b2e95..9cc1f1b75ed 100644
--- a/src/tools/clippy/tests/ui/float_cmp.stderr
+++ b/src/tools/clippy/tests/ui/float_cmp.stderr
@@ -1,5 +1,5 @@
 error: strict comparison of `f32` or `f64`
-  --> $DIR/float_cmp.rs:58:5
+  --> $DIR/float_cmp.rs:57:5
    |
 LL |     ONE as f64 != 2.0;
    |     ^^^^^^^^^^^^^^^^^ help: consider comparing them within some margin of error: `(ONE as f64 - 2.0).abs() > error_margin`
@@ -8,7 +8,7 @@ LL |     ONE as f64 != 2.0;
    = note: `f32::EPSILON` and `f64::EPSILON` are available for the `error_margin`
 
 error: strict comparison of `f32` or `f64`
-  --> $DIR/float_cmp.rs:63:5
+  --> $DIR/float_cmp.rs:62:5
    |
 LL |     x == 1.0;
    |     ^^^^^^^^ help: consider comparing them within some margin of error: `(x - 1.0).abs() < error_margin`
@@ -16,7 +16,7 @@ LL |     x == 1.0;
    = note: `f32::EPSILON` and `f64::EPSILON` are available for the `error_margin`
 
 error: strict comparison of `f32` or `f64`
-  --> $DIR/float_cmp.rs:66:5
+  --> $DIR/float_cmp.rs:65:5
    |
 LL |     twice(x) != twice(ONE as f64);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider comparing them within some margin of error: `(twice(x) - twice(ONE as f64)).abs() > error_margin`
@@ -24,7 +24,7 @@ LL |     twice(x) != twice(ONE as f64);
    = note: `f32::EPSILON` and `f64::EPSILON` are available for the `error_margin`
 
 error: strict comparison of `f32` or `f64`
-  --> $DIR/float_cmp.rs:86:5
+  --> $DIR/float_cmp.rs:85:5
    |
 LL |     NON_ZERO_ARRAY[i] == NON_ZERO_ARRAY[j];
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider comparing them within some margin of error: `(NON_ZERO_ARRAY[i] - NON_ZERO_ARRAY[j]).abs() < error_margin`
@@ -32,7 +32,7 @@ LL |     NON_ZERO_ARRAY[i] == NON_ZERO_ARRAY[j];
    = note: `f32::EPSILON` and `f64::EPSILON` are available for the `error_margin`
 
 error: strict comparison of `f32` or `f64` arrays
-  --> $DIR/float_cmp.rs:91:5
+  --> $DIR/float_cmp.rs:90:5
    |
 LL |     a1 == a2;
    |     ^^^^^^^^
@@ -40,7 +40,7 @@ LL |     a1 == a2;
    = note: `f32::EPSILON` and `f64::EPSILON` are available for the `error_margin`
 
 error: strict comparison of `f32` or `f64`
-  --> $DIR/float_cmp.rs:92:5
+  --> $DIR/float_cmp.rs:91:5
    |
 LL |     a1[0] == a2[0];
    |     ^^^^^^^^^^^^^^ help: consider comparing them within some margin of error: `(a1[0] - a2[0]).abs() < error_margin`
diff --git a/src/tools/clippy/tests/ui/for_loop_fixable.fixed b/src/tools/clippy/tests/ui/for_loop_fixable.fixed
index f44928d4083..f0e4835415f 100644
--- a/src/tools/clippy/tests/ui/for_loop_fixable.fixed
+++ b/src/tools/clippy/tests/ui/for_loop_fixable.fixed
@@ -29,7 +29,7 @@ impl Unrelated {
     clippy::unnecessary_mut_passed,
     clippy::similar_names
 )]
-#[allow(clippy::many_single_char_names, unused_variables)]
+#[allow(unused_variables)]
 fn main() {
     let mut vec = vec![1, 2, 3, 4];
 
diff --git a/src/tools/clippy/tests/ui/for_loop_fixable.rs b/src/tools/clippy/tests/ui/for_loop_fixable.rs
index 5b1eb3ee4dc..1edef175fb9 100644
--- a/src/tools/clippy/tests/ui/for_loop_fixable.rs
+++ b/src/tools/clippy/tests/ui/for_loop_fixable.rs
@@ -29,7 +29,7 @@ impl Unrelated {
     clippy::unnecessary_mut_passed,
     clippy::similar_names
 )]
-#[allow(clippy::many_single_char_names, unused_variables)]
+#[allow(unused_variables)]
 fn main() {
     let mut vec = vec![1, 2, 3, 4];
 
diff --git a/src/tools/clippy/tests/ui/if_let_some_result.fixed b/src/tools/clippy/tests/ui/if_let_some_result.fixed
deleted file mode 100644
index 1bddc47721e..00000000000
--- a/src/tools/clippy/tests/ui/if_let_some_result.fixed
+++ /dev/null
@@ -1,28 +0,0 @@
-// run-rustfix
-
-#![warn(clippy::if_let_some_result)]
-#![allow(dead_code)]
-
-fn str_to_int(x: &str) -> i32 {
-    if let Ok(y) = x.parse() { y } else { 0 }
-}
-
-fn str_to_int_ok(x: &str) -> i32 {
-    if let Ok(y) = x.parse() { y } else { 0 }
-}
-
-#[rustfmt::skip]
-fn strange_some_no_else(x: &str) -> i32 {
-    {
-        if let Ok(y) = x   .   parse()       {
-            return y;
-        };
-        0
-    }
-}
-
-fn negative() {
-    while let Some(1) = "".parse().ok() {}
-}
-
-fn main() {}
diff --git a/src/tools/clippy/tests/ui/if_let_some_result.rs b/src/tools/clippy/tests/ui/if_let_some_result.rs
deleted file mode 100644
index d4a52ec9881..00000000000
--- a/src/tools/clippy/tests/ui/if_let_some_result.rs
+++ /dev/null
@@ -1,28 +0,0 @@
-// run-rustfix
-
-#![warn(clippy::if_let_some_result)]
-#![allow(dead_code)]
-
-fn str_to_int(x: &str) -> i32 {
-    if let Some(y) = x.parse().ok() { y } else { 0 }
-}
-
-fn str_to_int_ok(x: &str) -> i32 {
-    if let Ok(y) = x.parse() { y } else { 0 }
-}
-
-#[rustfmt::skip]
-fn strange_some_no_else(x: &str) -> i32 {
-    {
-        if let Some(y) = x   .   parse()   .   ok   ()    {
-            return y;
-        };
-        0
-    }
-}
-
-fn negative() {
-    while let Some(1) = "".parse().ok() {}
-}
-
-fn main() {}
diff --git a/src/tools/clippy/tests/ui/if_then_panic.fixed b/src/tools/clippy/tests/ui/if_then_panic.fixed
new file mode 100644
index 00000000000..fc57ae0dfa5
--- /dev/null
+++ b/src/tools/clippy/tests/ui/if_then_panic.fixed
@@ -0,0 +1,34 @@
+// run-rustfix
+#![warn(clippy::if_then_panic)]
+
+fn main() {
+    let a = vec![1, 2, 3];
+    let c = Some(2);
+    if !a.is_empty()
+        && a.len() == 3
+        && c != None
+        && !a.is_empty()
+        && a.len() == 3
+        && !a.is_empty()
+        && a.len() == 3
+        && !a.is_empty()
+        && a.len() == 3
+    {
+        panic!("qaqaq{:?}", a);
+    }
+    assert!(a.is_empty(), "qaqaq{:?}", a);
+    assert!(a.is_empty(), "qwqwq");
+    if a.len() == 3 {
+        println!("qwq");
+        println!("qwq");
+        println!("qwq");
+    }
+    if let Some(b) = c {
+        panic!("orz {}", b);
+    }
+    if a.len() == 3 {
+        panic!("qaqaq");
+    } else {
+        println!("qwq");
+    }
+}
diff --git a/src/tools/clippy/tests/ui/if_then_panic.rs b/src/tools/clippy/tests/ui/if_then_panic.rs
new file mode 100644
index 00000000000..d1ac93d8d41
--- /dev/null
+++ b/src/tools/clippy/tests/ui/if_then_panic.rs
@@ -0,0 +1,38 @@
+// run-rustfix
+#![warn(clippy::if_then_panic)]
+
+fn main() {
+    let a = vec![1, 2, 3];
+    let c = Some(2);
+    if !a.is_empty()
+        && a.len() == 3
+        && c != None
+        && !a.is_empty()
+        && a.len() == 3
+        && !a.is_empty()
+        && a.len() == 3
+        && !a.is_empty()
+        && a.len() == 3
+    {
+        panic!("qaqaq{:?}", a);
+    }
+    if !a.is_empty() {
+        panic!("qaqaq{:?}", a);
+    }
+    if !a.is_empty() {
+        panic!("qwqwq");
+    }
+    if a.len() == 3 {
+        println!("qwq");
+        println!("qwq");
+        println!("qwq");
+    }
+    if let Some(b) = c {
+        panic!("orz {}", b);
+    }
+    if a.len() == 3 {
+        panic!("qaqaq");
+    } else {
+        println!("qwq");
+    }
+}
diff --git a/src/tools/clippy/tests/ui/if_then_panic.stderr b/src/tools/clippy/tests/ui/if_then_panic.stderr
new file mode 100644
index 00000000000..b92c9bdf674
--- /dev/null
+++ b/src/tools/clippy/tests/ui/if_then_panic.stderr
@@ -0,0 +1,20 @@
+error: only a `panic!` in `if`-then statement
+  --> $DIR/if_then_panic.rs:19:5
+   |
+LL | /     if !a.is_empty() {
+LL | |         panic!("qaqaq{:?}", a);
+LL | |     }
+   | |_____^ help: try: `assert!(a.is_empty(), "qaqaq{:?}", a);`
+   |
+   = note: `-D clippy::if-then-panic` implied by `-D warnings`
+
+error: only a `panic!` in `if`-then statement
+  --> $DIR/if_then_panic.rs:22:5
+   |
+LL | /     if !a.is_empty() {
+LL | |         panic!("qwqwq");
+LL | |     }
+   | |_____^ help: try: `assert!(a.is_empty(), "qwqwq");`
+
+error: aborting due to 2 previous errors
+
diff --git a/src/tools/clippy/tests/ui/infinite_loop.rs b/src/tools/clippy/tests/ui/infinite_loop.rs
index e518b2677b7..e86bd7bcf4f 100644
--- a/src/tools/clippy/tests/ui/infinite_loop.rs
+++ b/src/tools/clippy/tests/ui/infinite_loop.rs
@@ -16,7 +16,6 @@ fn foob() -> bool {
     unimplemented!()
 }
 
-#[allow(clippy::many_single_char_names)]
 fn immutable_condition() {
     // Should warn when all vars mentioned are immutable
     let y = 0;
diff --git a/src/tools/clippy/tests/ui/infinite_loop.stderr b/src/tools/clippy/tests/ui/infinite_loop.stderr
index 2736753c14b..69309b0da87 100644
--- a/src/tools/clippy/tests/ui/infinite_loop.stderr
+++ b/src/tools/clippy/tests/ui/infinite_loop.stderr
@@ -1,5 +1,5 @@
 error: variables in the condition are not mutated in the loop body
-  --> $DIR/infinite_loop.rs:23:11
+  --> $DIR/infinite_loop.rs:22:11
    |
 LL |     while y < 10 {
    |           ^^^^^^
@@ -8,7 +8,7 @@ LL |     while y < 10 {
    = note: this may lead to an infinite or to a never running loop
 
 error: variables in the condition are not mutated in the loop body
-  --> $DIR/infinite_loop.rs:28:11
+  --> $DIR/infinite_loop.rs:27:11
    |
 LL |     while y < 10 && x < 3 {
    |           ^^^^^^^^^^^^^^^
@@ -16,7 +16,7 @@ LL |     while y < 10 && x < 3 {
    = note: this may lead to an infinite or to a never running loop
 
 error: variables in the condition are not mutated in the loop body
-  --> $DIR/infinite_loop.rs:35:11
+  --> $DIR/infinite_loop.rs:34:11
    |
 LL |     while !cond {
    |           ^^^^^
@@ -24,7 +24,7 @@ LL |     while !cond {
    = note: this may lead to an infinite or to a never running loop
 
 error: variables in the condition are not mutated in the loop body
-  --> $DIR/infinite_loop.rs:79:11
+  --> $DIR/infinite_loop.rs:78:11
    |
 LL |     while i < 3 {
    |           ^^^^^
@@ -32,7 +32,7 @@ LL |     while i < 3 {
    = note: this may lead to an infinite or to a never running loop
 
 error: variables in the condition are not mutated in the loop body
-  --> $DIR/infinite_loop.rs:84:11
+  --> $DIR/infinite_loop.rs:83:11
    |
 LL |     while i < 3 && j > 0 {
    |           ^^^^^^^^^^^^^^
@@ -40,7 +40,7 @@ LL |     while i < 3 && j > 0 {
    = note: this may lead to an infinite or to a never running loop
 
 error: variables in the condition are not mutated in the loop body
-  --> $DIR/infinite_loop.rs:88:11
+  --> $DIR/infinite_loop.rs:87:11
    |
 LL |     while i < 3 {
    |           ^^^^^
@@ -48,7 +48,7 @@ LL |     while i < 3 {
    = note: this may lead to an infinite or to a never running loop
 
 error: variables in the condition are not mutated in the loop body
-  --> $DIR/infinite_loop.rs:103:11
+  --> $DIR/infinite_loop.rs:102:11
    |
 LL |     while i < 3 {
    |           ^^^^^
@@ -56,7 +56,7 @@ LL |     while i < 3 {
    = note: this may lead to an infinite or to a never running loop
 
 error: variables in the condition are not mutated in the loop body
-  --> $DIR/infinite_loop.rs:108:11
+  --> $DIR/infinite_loop.rs:107:11
    |
 LL |     while i < 3 {
    |           ^^^^^
@@ -64,7 +64,7 @@ LL |     while i < 3 {
    = note: this may lead to an infinite or to a never running loop
 
 error: variables in the condition are not mutated in the loop body
-  --> $DIR/infinite_loop.rs:174:15
+  --> $DIR/infinite_loop.rs:173:15
    |
 LL |         while self.count < n {
    |               ^^^^^^^^^^^^^^
@@ -72,7 +72,7 @@ LL |         while self.count < n {
    = note: this may lead to an infinite or to a never running loop
 
 error: variables in the condition are not mutated in the loop body
-  --> $DIR/infinite_loop.rs:182:11
+  --> $DIR/infinite_loop.rs:181:11
    |
 LL |     while y < 10 {
    |           ^^^^^^
@@ -82,7 +82,7 @@ LL |     while y < 10 {
    = help: rewrite it as `if cond { loop { } }`
 
 error: variables in the condition are not mutated in the loop body
-  --> $DIR/infinite_loop.rs:189:11
+  --> $DIR/infinite_loop.rs:188:11
    |
 LL |     while y < 10 {
    |           ^^^^^^
diff --git a/src/tools/clippy/tests/ui/inherent_to_string.rs b/src/tools/clippy/tests/ui/inherent_to_string.rs
index 6e65fdbd04e..aeb0a0c1e2e 100644
--- a/src/tools/clippy/tests/ui/inherent_to_string.rs
+++ b/src/tools/clippy/tests/ui/inherent_to_string.rs
@@ -1,6 +1,5 @@
 #![warn(clippy::inherent_to_string)]
 #![deny(clippy::inherent_to_string_shadow_display)]
-#![allow(clippy::many_single_char_names)]
 
 use std::fmt;
 
diff --git a/src/tools/clippy/tests/ui/inherent_to_string.stderr b/src/tools/clippy/tests/ui/inherent_to_string.stderr
index f5fcc193b4d..4f331f5bec9 100644
--- a/src/tools/clippy/tests/ui/inherent_to_string.stderr
+++ b/src/tools/clippy/tests/ui/inherent_to_string.stderr
@@ -1,5 +1,5 @@
 error: implementation of inherent method `to_string(&self) -> String` for type `A`
-  --> $DIR/inherent_to_string.rs:21:5
+  --> $DIR/inherent_to_string.rs:20:5
    |
 LL | /     fn to_string(&self) -> String {
 LL | |         "A.to_string()".to_string()
@@ -10,7 +10,7 @@ LL | |     }
    = help: implement trait `Display` for type `A` instead
 
 error: type `C` implements inherent method `to_string(&self) -> String` which shadows the implementation of `Display`
-  --> $DIR/inherent_to_string.rs:45:5
+  --> $DIR/inherent_to_string.rs:44:5
    |
 LL | /     fn to_string(&self) -> String {
 LL | |         "C.to_string()".to_string()
diff --git a/src/tools/clippy/tests/ui/iter_not_returning_iterator.rs b/src/tools/clippy/tests/ui/iter_not_returning_iterator.rs
new file mode 100644
index 00000000000..377f760b3c4
--- /dev/null
+++ b/src/tools/clippy/tests/ui/iter_not_returning_iterator.rs
@@ -0,0 +1,47 @@
+#![warn(clippy::iter_not_returning_iterator)]
+
+struct Data {
+    begin: u32,
+}
+
+struct Counter {
+    count: u32,
+}
+
+impl Data {
+    fn iter(&self) -> Counter {
+        todo!()
+    }
+
+    fn iter_mut(&self) -> Counter {
+        todo!()
+    }
+}
+
+struct Data2 {
+    begin: u32,
+}
+
+struct Counter2 {
+    count: u32,
+}
+
+impl Data2 {
+    fn iter(&self) -> Counter2 {
+        todo!()
+    }
+
+    fn iter_mut(&self) -> Counter2 {
+        todo!()
+    }
+}
+
+impl Iterator for Counter {
+    type Item = u32;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        todo!()
+    }
+}
+
+fn main() {}
diff --git a/src/tools/clippy/tests/ui/iter_not_returning_iterator.stderr b/src/tools/clippy/tests/ui/iter_not_returning_iterator.stderr
new file mode 100644
index 00000000000..2273cd0be66
--- /dev/null
+++ b/src/tools/clippy/tests/ui/iter_not_returning_iterator.stderr
@@ -0,0 +1,16 @@
+error: this method is named `iter` but its return type does not implement `Iterator`
+  --> $DIR/iter_not_returning_iterator.rs:30:5
+   |
+LL |     fn iter(&self) -> Counter2 {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::iter-not-returning-iterator` implied by `-D warnings`
+
+error: this method is named `iter_mut` but its return type does not implement `Iterator`
+  --> $DIR/iter_not_returning_iterator.rs:34:5
+   |
+LL |     fn iter_mut(&self) -> Counter2 {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+
diff --git a/src/tools/clippy/tests/ui/logic_bug.rs b/src/tools/clippy/tests/ui/logic_bug.rs
index a01c6ef99db..4eaa2dd98eb 100644
--- a/src/tools/clippy/tests/ui/logic_bug.rs
+++ b/src/tools/clippy/tests/ui/logic_bug.rs
@@ -1,4 +1,4 @@
-#![allow(unused, clippy::many_single_char_names, clippy::diverging_sub_expression)]
+#![allow(unused, clippy::diverging_sub_expression)]
 #![warn(clippy::logic_bug)]
 
 fn main() {
diff --git a/src/tools/clippy/tests/ui/manual_split_once.fixed b/src/tools/clippy/tests/ui/manual_split_once.fixed
index 3a0332939d4..992baf1f185 100644
--- a/src/tools/clippy/tests/ui/manual_split_once.fixed
+++ b/src/tools/clippy/tests/ui/manual_split_once.fixed
@@ -36,6 +36,12 @@ fn main() {
 
     // Don't lint, slices don't have `split_once`
     let _ = [0, 1, 2].splitn(2, |&x| x == 1).nth(1).unwrap();
+
+    // `rsplitn` gives the results in the reverse order of `rsplit_once`
+    let _ = "key=value".rsplit_once('=').unwrap().1;
+    let _ = "key=value".rsplit_once('=').map_or("key=value", |x| x.0);
+    let _ = "key=value".rsplit_once('=').map(|x| x.1);
+    let (_, _) = "key=value".rsplit_once('=').map(|(x, y)| (y, x)).unwrap();
 }
 
 fn _msrv_1_51() {
diff --git a/src/tools/clippy/tests/ui/manual_split_once.rs b/src/tools/clippy/tests/ui/manual_split_once.rs
index e6093b63fe8..4f92ab6b812 100644
--- a/src/tools/clippy/tests/ui/manual_split_once.rs
+++ b/src/tools/clippy/tests/ui/manual_split_once.rs
@@ -36,6 +36,12 @@ fn main() {
 
     // Don't lint, slices don't have `split_once`
     let _ = [0, 1, 2].splitn(2, |&x| x == 1).nth(1).unwrap();
+
+    // `rsplitn` gives the results in the reverse order of `rsplit_once`
+    let _ = "key=value".rsplitn(2, '=').next().unwrap();
+    let _ = "key=value".rsplitn(2, '=').nth(1).unwrap();
+    let _ = "key=value".rsplitn(2, '=').nth(0);
+    let (_, _) = "key=value".rsplitn(2, '=').next_tuple().unwrap();
 }
 
 fn _msrv_1_51() {
diff --git a/src/tools/clippy/tests/ui/manual_split_once.stderr b/src/tools/clippy/tests/ui/manual_split_once.stderr
index 4f15196b469..7bea2303d92 100644
--- a/src/tools/clippy/tests/ui/manual_split_once.stderr
+++ b/src/tools/clippy/tests/ui/manual_split_once.stderr
@@ -72,11 +72,35 @@ error: manual implementation of `split_once`
 LL |         let _ = s.splitn(2, "key=value").skip(1).next()?;
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `s.split_once("key=value")?.1`
 
+error: manual implementation of `rsplit_once`
+  --> $DIR/manual_split_once.rs:41:13
+   |
+LL |     let _ = "key=value".rsplitn(2, '=').next().unwrap();
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `"key=value".rsplit_once('=').unwrap().1`
+
+error: manual implementation of `rsplit_once`
+  --> $DIR/manual_split_once.rs:42:13
+   |
+LL |     let _ = "key=value".rsplitn(2, '=').nth(1).unwrap();
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `"key=value".rsplit_once('=').map_or("key=value", |x| x.0)`
+
+error: manual implementation of `rsplit_once`
+  --> $DIR/manual_split_once.rs:43:13
+   |
+LL |     let _ = "key=value".rsplitn(2, '=').nth(0);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `"key=value".rsplit_once('=').map(|x| x.1)`
+
+error: manual implementation of `rsplit_once`
+  --> $DIR/manual_split_once.rs:44:18
+   |
+LL |     let (_, _) = "key=value".rsplitn(2, '=').next_tuple().unwrap();
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `"key=value".rsplit_once('=').map(|(x, y)| (y, x))`
+
 error: manual implementation of `split_once`
-  --> $DIR/manual_split_once.rs:49:13
+  --> $DIR/manual_split_once.rs:55:13
    |
 LL |     let _ = "key=value".splitn(2, '=').nth(1).unwrap();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `"key=value".split_once('=').unwrap().1`
 
-error: aborting due to 13 previous errors
+error: aborting due to 17 previous errors
 
diff --git a/src/tools/clippy/tests/ui/many_single_char_names.rs b/src/tools/clippy/tests/ui/many_single_char_names.rs
index 80800e48724..65769819110 100644
--- a/src/tools/clippy/tests/ui/many_single_char_names.rs
+++ b/src/tools/clippy/tests/ui/many_single_char_names.rs
@@ -1,4 +1,4 @@
-#[warn(clippy::many_single_char_names)]
+#![warn(clippy::many_single_char_names)]
 
 fn bla() {
     let a: i32;
diff --git a/src/tools/clippy/tests/ui/map_flatten.fixed b/src/tools/clippy/tests/ui/map_flatten.fixed
index 18846c898da..fec3a95edd6 100644
--- a/src/tools/clippy/tests/ui/map_flatten.fixed
+++ b/src/tools/clippy/tests/ui/map_flatten.fixed
@@ -4,6 +4,7 @@
 #![allow(clippy::let_underscore_drop)]
 #![allow(clippy::missing_docs_in_private_items)]
 #![allow(clippy::map_identity)]
+#![allow(clippy::redundant_closure)]
 #![allow(clippy::unnecessary_wraps)]
 #![feature(result_flattening)]
 
diff --git a/src/tools/clippy/tests/ui/map_flatten.rs b/src/tools/clippy/tests/ui/map_flatten.rs
index 01db27876da..aa1f76e335a 100644
--- a/src/tools/clippy/tests/ui/map_flatten.rs
+++ b/src/tools/clippy/tests/ui/map_flatten.rs
@@ -4,6 +4,7 @@
 #![allow(clippy::let_underscore_drop)]
 #![allow(clippy::missing_docs_in_private_items)]
 #![allow(clippy::map_identity)]
+#![allow(clippy::redundant_closure)]
 #![allow(clippy::unnecessary_wraps)]
 #![feature(result_flattening)]
 
diff --git a/src/tools/clippy/tests/ui/map_flatten.stderr b/src/tools/clippy/tests/ui/map_flatten.stderr
index 38457c8ea4d..bcd2047e6fa 100644
--- a/src/tools/clippy/tests/ui/map_flatten.stderr
+++ b/src/tools/clippy/tests/ui/map_flatten.stderr
@@ -1,5 +1,5 @@
 error: called `map(..).flatten()` on an `Iterator`
-  --> $DIR/map_flatten.rs:17:46
+  --> $DIR/map_flatten.rs:18:46
    |
 LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id).flatten().collect();
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using `filter_map` instead: `.filter_map(option_id)`
@@ -7,37 +7,37 @@ LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id).flatten().coll
    = note: `-D clippy::map-flatten` implied by `-D warnings`
 
 error: called `map(..).flatten()` on an `Iterator`
-  --> $DIR/map_flatten.rs:18:46
+  --> $DIR/map_flatten.rs:19:46
    |
 LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id_ref).flatten().collect();
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using `filter_map` instead: `.filter_map(option_id_ref)`
 
 error: called `map(..).flatten()` on an `Iterator`
-  --> $DIR/map_flatten.rs:19:46
+  --> $DIR/map_flatten.rs:20:46
    |
 LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id_closure).flatten().collect();
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using `filter_map` instead: `.filter_map(option_id_closure)`
 
 error: called `map(..).flatten()` on an `Iterator`
-  --> $DIR/map_flatten.rs:20:46
+  --> $DIR/map_flatten.rs:21:46
    |
 LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(|x| x.checked_add(1)).flatten().collect();
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using `filter_map` instead: `.filter_map(|x| x.checked_add(1))`
 
 error: called `map(..).flatten()` on an `Iterator`
-  --> $DIR/map_flatten.rs:23:46
+  --> $DIR/map_flatten.rs:24:46
    |
 LL |     let _: Vec<_> = vec![5_i8; 6].into_iter().map(|x| 0..x).flatten().collect();
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^ help: try using `flat_map` instead: `.flat_map(|x| 0..x)`
 
 error: called `map(..).flatten()` on an `Option`
-  --> $DIR/map_flatten.rs:26:39
+  --> $DIR/map_flatten.rs:27:39
    |
 LL |     let _: Option<_> = (Some(Some(1))).map(|x| x).flatten();
    |                                       ^^^^^^^^^^^^^^^^^^^^^ help: try using `and_then` instead: `.and_then(|x| x)`
 
 error: called `map(..).flatten()` on an `Result`
-  --> $DIR/map_flatten.rs:29:41
+  --> $DIR/map_flatten.rs:30:41
    |
 LL |     let _: Result<_, &str> = (Ok(Ok(1))).map(|x| x).flatten();
    |                                         ^^^^^^^^^^^^^^^^^^^^^ help: try using `and_then` instead: `.and_then(|x| x)`
diff --git a/src/tools/clippy/tests/ui/match_result_ok.fixed b/src/tools/clippy/tests/ui/match_result_ok.fixed
new file mode 100644
index 00000000000..d4760a97567
--- /dev/null
+++ b/src/tools/clippy/tests/ui/match_result_ok.fixed
@@ -0,0 +1,63 @@
+// run-rustfix
+
+#![warn(clippy::match_result_ok)]
+#![allow(clippy::boxed_local)]
+#![allow(dead_code)]
+
+// Checking `if` cases
+
+fn str_to_int(x: &str) -> i32 {
+    if let Ok(y) = x.parse() { y } else { 0 }
+}
+
+fn str_to_int_ok(x: &str) -> i32 {
+    if let Ok(y) = x.parse() { y } else { 0 }
+}
+
+#[rustfmt::skip]
+fn strange_some_no_else(x: &str) -> i32 {
+    {
+        if let Ok(y) = x   .   parse()       {
+            return y;
+        };
+        0
+    }
+}
+
+// Checking `while` cases
+
+struct Wat {
+    counter: i32,
+}
+
+impl Wat {
+    fn next(&mut self) -> Result<i32, &str> {
+        self.counter += 1;
+        if self.counter < 5 {
+            Ok(self.counter)
+        } else {
+            Err("Oh no")
+        }
+    }
+}
+
+fn base_1(x: i32) {
+    let mut wat = Wat { counter: x };
+    while let Ok(a) = wat.next() {
+        println!("{}", a);
+    }
+}
+
+fn base_2(x: i32) {
+    let mut wat = Wat { counter: x };
+    while let Ok(a) = wat.next() {
+        println!("{}", a);
+    }
+}
+
+fn base_3(test_func: Box<Result<i32, &str>>) {
+    // Expected to stay as is
+    while let Some(_b) = test_func.ok() {}
+}
+
+fn main() {}
diff --git a/src/tools/clippy/tests/ui/match_result_ok.rs b/src/tools/clippy/tests/ui/match_result_ok.rs
new file mode 100644
index 00000000000..0b818723d98
--- /dev/null
+++ b/src/tools/clippy/tests/ui/match_result_ok.rs
@@ -0,0 +1,63 @@
+// run-rustfix
+
+#![warn(clippy::match_result_ok)]
+#![allow(clippy::boxed_local)]
+#![allow(dead_code)]
+
+// Checking `if` cases
+
+fn str_to_int(x: &str) -> i32 {
+    if let Some(y) = x.parse().ok() { y } else { 0 }
+}
+
+fn str_to_int_ok(x: &str) -> i32 {
+    if let Ok(y) = x.parse() { y } else { 0 }
+}
+
+#[rustfmt::skip]
+fn strange_some_no_else(x: &str) -> i32 {
+    {
+        if let Some(y) = x   .   parse()   .   ok   ()    {
+            return y;
+        };
+        0
+    }
+}
+
+// Checking `while` cases
+
+struct Wat {
+    counter: i32,
+}
+
+impl Wat {
+    fn next(&mut self) -> Result<i32, &str> {
+        self.counter += 1;
+        if self.counter < 5 {
+            Ok(self.counter)
+        } else {
+            Err("Oh no")
+        }
+    }
+}
+
+fn base_1(x: i32) {
+    let mut wat = Wat { counter: x };
+    while let Some(a) = wat.next().ok() {
+        println!("{}", a);
+    }
+}
+
+fn base_2(x: i32) {
+    let mut wat = Wat { counter: x };
+    while let Ok(a) = wat.next() {
+        println!("{}", a);
+    }
+}
+
+fn base_3(test_func: Box<Result<i32, &str>>) {
+    // Expected to stay as is
+    while let Some(_b) = test_func.ok() {}
+}
+
+fn main() {}
diff --git a/src/tools/clippy/tests/ui/if_let_some_result.stderr b/src/tools/clippy/tests/ui/match_result_ok.stderr
index bc3a5e7698d..cc3bc8c76ff 100644
--- a/src/tools/clippy/tests/ui/if_let_some_result.stderr
+++ b/src/tools/clippy/tests/ui/match_result_ok.stderr
@@ -1,17 +1,17 @@
 error: matching on `Some` with `ok()` is redundant
-  --> $DIR/if_let_some_result.rs:7:5
+  --> $DIR/match_result_ok.rs:10:5
    |
 LL |     if let Some(y) = x.parse().ok() { y } else { 0 }
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: `-D clippy::if-let-some-result` implied by `-D warnings`
+   = note: `-D clippy::match-result-ok` implied by `-D warnings`
 help: consider matching on `Ok(y)` and removing the call to `ok` instead
    |
 LL |     if let Ok(y) = x.parse() { y } else { 0 }
    |     ~~~~~~~~~~~~~~~~~~~~~~~~
 
 error: matching on `Some` with `ok()` is redundant
-  --> $DIR/if_let_some_result.rs:17:9
+  --> $DIR/match_result_ok.rs:20:9
    |
 LL |         if let Some(y) = x   .   parse()   .   ok   ()    {
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -21,5 +21,16 @@ help: consider matching on `Ok(y)` and removing the call to `ok` instead
 LL |         if let Ok(y) = x   .   parse()       {
    |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-error: aborting due to 2 previous errors
+error: matching on `Some` with `ok()` is redundant
+  --> $DIR/match_result_ok.rs:46:5
+   |
+LL |     while let Some(a) = wat.next().ok() {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: consider matching on `Ok(a)` and removing the call to `ok` instead
+   |
+LL |     while let Ok(a) = wat.next() {
+   |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+error: aborting due to 3 previous errors
 
diff --git a/src/tools/clippy/tests/ui/match_single_binding.fixed b/src/tools/clippy/tests/ui/match_single_binding.fixed
index 30bf6402253..b4ec525ada0 100644
--- a/src/tools/clippy/tests/ui/match_single_binding.fixed
+++ b/src/tools/clippy/tests/ui/match_single_binding.fixed
@@ -1,7 +1,7 @@
 // run-rustfix
 
 #![warn(clippy::match_single_binding)]
-#![allow(unused_variables, clippy::many_single_char_names, clippy::toplevel_ref_arg)]
+#![allow(unused_variables, clippy::toplevel_ref_arg)]
 
 struct Point {
     x: i32,
diff --git a/src/tools/clippy/tests/ui/match_single_binding.rs b/src/tools/clippy/tests/ui/match_single_binding.rs
index d8bb80d8b96..e04c4018b98 100644
--- a/src/tools/clippy/tests/ui/match_single_binding.rs
+++ b/src/tools/clippy/tests/ui/match_single_binding.rs
@@ -1,7 +1,7 @@
 // run-rustfix
 
 #![warn(clippy::match_single_binding)]
-#![allow(unused_variables, clippy::many_single_char_names, clippy::toplevel_ref_arg)]
+#![allow(unused_variables, clippy::toplevel_ref_arg)]
 
 struct Point {
     x: i32,
diff --git a/src/tools/clippy/tests/ui/mut_key.rs b/src/tools/clippy/tests/ui/mut_key.rs
index 2d227e6654c..1c0ba664580 100644
--- a/src/tools/clippy/tests/ui/mut_key.rs
+++ b/src/tools/clippy/tests/ui/mut_key.rs
@@ -1,6 +1,9 @@
-use std::collections::{HashMap, HashSet};
+use std::cell::Cell;
+use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
 use std::hash::{Hash, Hasher};
+use std::rc::Rc;
 use std::sync::atomic::{AtomicUsize, Ordering::Relaxed};
+use std::sync::Arc;
 
 struct Key(AtomicUsize);
 
@@ -31,11 +34,19 @@ fn should_not_take_this_arg(m: &mut HashMap<Key, usize>, _n: usize) -> HashSet<K
 
 fn this_is_ok(_m: &mut HashMap<usize, Key>) {}
 
+// Raw pointers are hashed by the address they point to, so it doesn't matter if they point to a
+// type with interior mutability.  See:
+// - clippy issue: https://github.com/rust-lang/rust-clippy/issues/6745
+// - std lib: https://github.com/rust-lang/rust/blob/1.54.0/library/core/src/hash/mod.rs#L717-L736
+// So these are OK:
+fn raw_ptr_is_ok(_m: &mut HashMap<*const Key, ()>) {}
+fn raw_mut_ptr_is_ok(_m: &mut HashMap<*mut Key, ()>) {}
+
 #[allow(unused)]
 trait Trait {
     type AssociatedType;
 
-    fn trait_fn(&self, set: std::collections::HashSet<Self::AssociatedType>);
+    fn trait_fn(&self, set: HashSet<Self::AssociatedType>);
 }
 
 fn generics_are_ok_too<K>(_m: &mut HashSet<K>) {
@@ -52,4 +63,23 @@ fn main() {
     tuples::<Key>(&mut HashMap::new());
     tuples::<()>(&mut HashMap::new());
     tuples_bad::<()>(&mut HashMap::new());
+
+    raw_ptr_is_ok(&mut HashMap::new());
+    raw_mut_ptr_is_ok(&mut HashMap::new());
+
+    let _map = HashMap::<Cell<usize>, usize>::new();
+    let _map = HashMap::<&mut Cell<usize>, usize>::new();
+    let _map = HashMap::<&mut usize, usize>::new();
+    // Collection types from `std` who's impl of `Hash` or `Ord` delegate their type parameters
+    let _map = HashMap::<Vec<Cell<usize>>, usize>::new();
+    let _map = HashMap::<BTreeMap<Cell<usize>, ()>, usize>::new();
+    let _map = HashMap::<BTreeMap<(), Cell<usize>>, usize>::new();
+    let _map = HashMap::<BTreeSet<Cell<usize>>, usize>::new();
+    let _map = HashMap::<Option<Cell<usize>>, usize>::new();
+    let _map = HashMap::<Option<Vec<Cell<usize>>>, usize>::new();
+    let _map = HashMap::<Result<&mut usize, ()>, usize>::new();
+    // Smart pointers from `std` who's impl of `Hash` or `Ord` delegate their type parameters
+    let _map = HashMap::<Box<Cell<usize>>, usize>::new();
+    let _map = HashMap::<Rc<Cell<usize>>, usize>::new();
+    let _map = HashMap::<Arc<Cell<usize>>, usize>::new();
 }
diff --git a/src/tools/clippy/tests/ui/mut_key.stderr b/src/tools/clippy/tests/ui/mut_key.stderr
index a8460b06ca6..25dd029b16e 100644
--- a/src/tools/clippy/tests/ui/mut_key.stderr
+++ b/src/tools/clippy/tests/ui/mut_key.stderr
@@ -1,5 +1,5 @@
 error: mutable key type
-  --> $DIR/mut_key.rs:27:32
+  --> $DIR/mut_key.rs:30:32
    |
 LL | fn should_not_take_this_arg(m: &mut HashMap<Key, usize>, _n: usize) -> HashSet<Key> {
    |                                ^^^^^^^^^^^^^^^^^^^^^^^^
@@ -7,22 +7,100 @@ LL | fn should_not_take_this_arg(m: &mut HashMap<Key, usize>, _n: usize) -> Hash
    = note: `-D clippy::mutable-key-type` implied by `-D warnings`
 
 error: mutable key type
-  --> $DIR/mut_key.rs:27:72
+  --> $DIR/mut_key.rs:30:72
    |
 LL | fn should_not_take_this_arg(m: &mut HashMap<Key, usize>, _n: usize) -> HashSet<Key> {
    |                                                                        ^^^^^^^^^^^^
 
 error: mutable key type
-  --> $DIR/mut_key.rs:28:5
+  --> $DIR/mut_key.rs:31:5
    |
 LL |     let _other: HashMap<Key, bool> = HashMap::new();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: mutable key type
-  --> $DIR/mut_key.rs:47:22
+  --> $DIR/mut_key.rs:58:22
    |
 LL | fn tuples_bad<U>(_m: &mut HashMap<(Key, U), bool>) {}
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 4 previous errors
+error: mutable key type
+  --> $DIR/mut_key.rs:70:5
+   |
+LL |     let _map = HashMap::<Cell<usize>, usize>::new();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: mutable key type
+  --> $DIR/mut_key.rs:71:5
+   |
+LL |     let _map = HashMap::<&mut Cell<usize>, usize>::new();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: mutable key type
+  --> $DIR/mut_key.rs:72:5
+   |
+LL |     let _map = HashMap::<&mut usize, usize>::new();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: mutable key type
+  --> $DIR/mut_key.rs:74:5
+   |
+LL |     let _map = HashMap::<Vec<Cell<usize>>, usize>::new();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: mutable key type
+  --> $DIR/mut_key.rs:75:5
+   |
+LL |     let _map = HashMap::<BTreeMap<Cell<usize>, ()>, usize>::new();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: mutable key type
+  --> $DIR/mut_key.rs:76:5
+   |
+LL |     let _map = HashMap::<BTreeMap<(), Cell<usize>>, usize>::new();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: mutable key type
+  --> $DIR/mut_key.rs:77:5
+   |
+LL |     let _map = HashMap::<BTreeSet<Cell<usize>>, usize>::new();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: mutable key type
+  --> $DIR/mut_key.rs:78:5
+   |
+LL |     let _map = HashMap::<Option<Cell<usize>>, usize>::new();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: mutable key type
+  --> $DIR/mut_key.rs:79:5
+   |
+LL |     let _map = HashMap::<Option<Vec<Cell<usize>>>, usize>::new();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: mutable key type
+  --> $DIR/mut_key.rs:80:5
+   |
+LL |     let _map = HashMap::<Result<&mut usize, ()>, usize>::new();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: mutable key type
+  --> $DIR/mut_key.rs:82:5
+   |
+LL |     let _map = HashMap::<Box<Cell<usize>>, usize>::new();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: mutable key type
+  --> $DIR/mut_key.rs:83:5
+   |
+LL |     let _map = HashMap::<Rc<Cell<usize>>, usize>::new();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: mutable key type
+  --> $DIR/mut_key.rs:84:5
+   |
+LL |     let _map = HashMap::<Arc<Cell<usize>>, usize>::new();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 17 previous errors
 
diff --git a/src/tools/clippy/tests/ui/needless_borrow.fixed b/src/tools/clippy/tests/ui/needless_borrow.fixed
index a87171dc3f2..42c2bb9f414 100644
--- a/src/tools/clippy/tests/ui/needless_borrow.fixed
+++ b/src/tools/clippy/tests/ui/needless_borrow.fixed
@@ -1,17 +1,16 @@
 // run-rustfix
 
-#![allow(clippy::needless_borrowed_reference)]
-
-fn x(y: &i32) -> i32 {
-    *y
-}
-
 #[warn(clippy::all, clippy::needless_borrow)]
 #[allow(unused_variables)]
 fn main() {
     let a = 5;
-    let b = x(&a);
-    let c = x(&a);
+    let _ = x(&a); // no warning
+    let _ = x(&a); // warn
+
+    let mut b = 5;
+    mut_ref(&mut b); // no warning
+    mut_ref(&mut b); // warn
+
     let s = &String::from("hi");
     let s_ident = f(&s); // should not error, because `&String` implements Copy, but `String` does not
     let g_val = g(&Vec::new()); // should not error, because `&Vec<T>` derefs to `&[T]`
@@ -29,6 +28,15 @@ fn main() {
     };
 }
 
+#[allow(clippy::needless_borrowed_reference)]
+fn x(y: &i32) -> i32 {
+    *y
+}
+
+fn mut_ref(y: &mut i32) {
+    *y = 5;
+}
+
 fn f<T: Copy>(y: &T) -> T {
     *y
 }
diff --git a/src/tools/clippy/tests/ui/needless_borrow.rs b/src/tools/clippy/tests/ui/needless_borrow.rs
index 059dc8ceac3..31977416bc7 100644
--- a/src/tools/clippy/tests/ui/needless_borrow.rs
+++ b/src/tools/clippy/tests/ui/needless_borrow.rs
@@ -1,17 +1,16 @@
 // run-rustfix
 
-#![allow(clippy::needless_borrowed_reference)]
-
-fn x(y: &i32) -> i32 {
-    *y
-}
-
 #[warn(clippy::all, clippy::needless_borrow)]
 #[allow(unused_variables)]
 fn main() {
     let a = 5;
-    let b = x(&a);
-    let c = x(&&a);
+    let _ = x(&a); // no warning
+    let _ = x(&&a); // warn
+
+    let mut b = 5;
+    mut_ref(&mut b); // no warning
+    mut_ref(&mut &mut b); // warn
+
     let s = &String::from("hi");
     let s_ident = f(&s); // should not error, because `&String` implements Copy, but `String` does not
     let g_val = g(&Vec::new()); // should not error, because `&Vec<T>` derefs to `&[T]`
@@ -29,6 +28,15 @@ fn main() {
     };
 }
 
+#[allow(clippy::needless_borrowed_reference)]
+fn x(y: &i32) -> i32 {
+    *y
+}
+
+fn mut_ref(y: &mut i32) {
+    *y = 5;
+}
+
 fn f<T: Copy>(y: &T) -> T {
     *y
 }
diff --git a/src/tools/clippy/tests/ui/needless_borrow.stderr b/src/tools/clippy/tests/ui/needless_borrow.stderr
index 6eddf26db06..012d62e2871 100644
--- a/src/tools/clippy/tests/ui/needless_borrow.stderr
+++ b/src/tools/clippy/tests/ui/needless_borrow.stderr
@@ -1,16 +1,22 @@
 error: this expression borrows a reference (`&i32`) that is immediately dereferenced by the compiler
-  --> $DIR/needless_borrow.rs:14:15
+  --> $DIR/needless_borrow.rs:8:15
    |
-LL |     let c = x(&&a);
+LL |     let _ = x(&&a); // warn
    |               ^^^ help: change this to: `&a`
    |
    = note: `-D clippy::needless-borrow` implied by `-D warnings`
 
+error: this expression borrows a reference (`&mut i32`) that is immediately dereferenced by the compiler
+  --> $DIR/needless_borrow.rs:12:13
+   |
+LL |     mut_ref(&mut &mut b); // warn
+   |             ^^^^^^^^^^^ help: change this to: `&mut b`
+
 error: this expression borrows a reference (`&i32`) that is immediately dereferenced by the compiler
-  --> $DIR/needless_borrow.rs:27:15
+  --> $DIR/needless_borrow.rs:26:15
    |
 LL |         46 => &&a,
    |               ^^^ help: change this to: `&a`
 
-error: aborting due to 2 previous errors
+error: aborting due to 3 previous errors
 
diff --git a/src/tools/clippy/tests/ui/needless_pass_by_value.rs b/src/tools/clippy/tests/ui/needless_pass_by_value.rs
index 7a9ba55590d..5a35b100afe 100644
--- a/src/tools/clippy/tests/ui/needless_pass_by_value.rs
+++ b/src/tools/clippy/tests/ui/needless_pass_by_value.rs
@@ -3,7 +3,6 @@
     dead_code,
     clippy::single_match,
     clippy::redundant_pattern_matching,
-    clippy::many_single_char_names,
     clippy::option_option,
     clippy::redundant_clone
 )]
diff --git a/src/tools/clippy/tests/ui/needless_pass_by_value.stderr b/src/tools/clippy/tests/ui/needless_pass_by_value.stderr
index 2f61ba241c4..d960c86a9f0 100644
--- a/src/tools/clippy/tests/ui/needless_pass_by_value.stderr
+++ b/src/tools/clippy/tests/ui/needless_pass_by_value.stderr
@@ -1,5 +1,5 @@
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:18:23
+  --> $DIR/needless_pass_by_value.rs:17:23
    |
 LL | fn foo<T: Default>(v: Vec<T>, w: Vec<T>, mut x: Vec<T>, y: Vec<T>) -> Vec<T> {
    |                       ^^^^^^ help: consider changing the type to: `&[T]`
@@ -7,55 +7,55 @@ LL | fn foo<T: Default>(v: Vec<T>, w: Vec<T>, mut x: Vec<T>, y: Vec<T>) -> Vec<T
    = note: `-D clippy::needless-pass-by-value` implied by `-D warnings`
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:32:11
+  --> $DIR/needless_pass_by_value.rs:31:11
    |
 LL | fn bar(x: String, y: Wrapper) {
    |           ^^^^^^ help: consider changing the type to: `&str`
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:32:22
+  --> $DIR/needless_pass_by_value.rs:31:22
    |
 LL | fn bar(x: String, y: Wrapper) {
    |                      ^^^^^^^ help: consider taking a reference instead: `&Wrapper`
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:38:71
+  --> $DIR/needless_pass_by_value.rs:37:71
    |
 LL | fn test_borrow_trait<T: Borrow<str>, U: AsRef<str>, V>(t: T, u: U, v: V) {
    |                                                                       ^ help: consider taking a reference instead: `&V`
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:50:18
+  --> $DIR/needless_pass_by_value.rs:49:18
    |
 LL | fn test_match(x: Option<Option<String>>, y: Option<Option<String>>) {
    |                  ^^^^^^^^^^^^^^^^^^^^^^ help: consider taking a reference instead: `&Option<Option<String>>`
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:63:24
+  --> $DIR/needless_pass_by_value.rs:62:24
    |
 LL | fn test_destructure(x: Wrapper, y: Wrapper, z: Wrapper) {
    |                        ^^^^^^^ help: consider taking a reference instead: `&Wrapper`
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:63:36
+  --> $DIR/needless_pass_by_value.rs:62:36
    |
 LL | fn test_destructure(x: Wrapper, y: Wrapper, z: Wrapper) {
    |                                    ^^^^^^^ help: consider taking a reference instead: `&Wrapper`
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:79:49
+  --> $DIR/needless_pass_by_value.rs:78:49
    |
 LL | fn test_blanket_ref<T: Foo, S: Serialize>(_foo: T, _serializable: S) {}
    |                                                 ^ help: consider taking a reference instead: `&T`
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:81:18
+  --> $DIR/needless_pass_by_value.rs:80:18
    |
 LL | fn issue_2114(s: String, t: String, u: Vec<i32>, v: Vec<i32>) {
    |                  ^^^^^^ help: consider taking a reference instead: `&String`
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:81:29
+  --> $DIR/needless_pass_by_value.rs:80:29
    |
 LL | fn issue_2114(s: String, t: String, u: Vec<i32>, v: Vec<i32>) {
    |                             ^^^^^^
@@ -70,13 +70,13 @@ LL |     let _ = t.to_string();
    |             ~~~~~~~~~~~~~
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:81:40
+  --> $DIR/needless_pass_by_value.rs:80:40
    |
 LL | fn issue_2114(s: String, t: String, u: Vec<i32>, v: Vec<i32>) {
    |                                        ^^^^^^^^ help: consider taking a reference instead: `&Vec<i32>`
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:81:53
+  --> $DIR/needless_pass_by_value.rs:80:53
    |
 LL | fn issue_2114(s: String, t: String, u: Vec<i32>, v: Vec<i32>) {
    |                                                     ^^^^^^^^
@@ -91,85 +91,85 @@ LL |     let _ = v.to_owned();
    |             ~~~~~~~~~~~~
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:94:12
+  --> $DIR/needless_pass_by_value.rs:93:12
    |
 LL |         s: String,
    |            ^^^^^^ help: consider changing the type to: `&str`
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:95:12
+  --> $DIR/needless_pass_by_value.rs:94:12
    |
 LL |         t: String,
    |            ^^^^^^ help: consider taking a reference instead: `&String`
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:104:23
+  --> $DIR/needless_pass_by_value.rs:103:23
    |
 LL |     fn baz(&self, _u: U, _s: Self) {}
    |                       ^ help: consider taking a reference instead: `&U`
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:104:30
+  --> $DIR/needless_pass_by_value.rs:103:30
    |
 LL |     fn baz(&self, _u: U, _s: Self) {}
    |                              ^^^^ help: consider taking a reference instead: `&Self`
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:126:24
+  --> $DIR/needless_pass_by_value.rs:125:24
    |
 LL | fn bar_copy(x: u32, y: CopyWrapper) {
    |                        ^^^^^^^^^^^ help: consider taking a reference instead: `&CopyWrapper`
    |
 help: consider marking this type as `Copy`
-  --> $DIR/needless_pass_by_value.rs:124:1
+  --> $DIR/needless_pass_by_value.rs:123:1
    |
 LL | struct CopyWrapper(u32);
    | ^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:132:29
+  --> $DIR/needless_pass_by_value.rs:131:29
    |
 LL | fn test_destructure_copy(x: CopyWrapper, y: CopyWrapper, z: CopyWrapper) {
    |                             ^^^^^^^^^^^ help: consider taking a reference instead: `&CopyWrapper`
    |
 help: consider marking this type as `Copy`
-  --> $DIR/needless_pass_by_value.rs:124:1
+  --> $DIR/needless_pass_by_value.rs:123:1
    |
 LL | struct CopyWrapper(u32);
    | ^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:132:45
+  --> $DIR/needless_pass_by_value.rs:131:45
    |
 LL | fn test_destructure_copy(x: CopyWrapper, y: CopyWrapper, z: CopyWrapper) {
    |                                             ^^^^^^^^^^^ help: consider taking a reference instead: `&CopyWrapper`
    |
 help: consider marking this type as `Copy`
-  --> $DIR/needless_pass_by_value.rs:124:1
+  --> $DIR/needless_pass_by_value.rs:123:1
    |
 LL | struct CopyWrapper(u32);
    | ^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:132:61
+  --> $DIR/needless_pass_by_value.rs:131:61
    |
 LL | fn test_destructure_copy(x: CopyWrapper, y: CopyWrapper, z: CopyWrapper) {
    |                                                             ^^^^^^^^^^^ help: consider taking a reference instead: `&CopyWrapper`
    |
 help: consider marking this type as `Copy`
-  --> $DIR/needless_pass_by_value.rs:124:1
+  --> $DIR/needless_pass_by_value.rs:123:1
    |
 LL | struct CopyWrapper(u32);
    | ^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:144:40
+  --> $DIR/needless_pass_by_value.rs:143:40
    |
 LL | fn some_fun<'b, S: Bar<'b, ()>>(_item: S) {}
    |                                        ^ help: consider taking a reference instead: `&S`
 
 error: this argument is passed by value, but not consumed in the function body
-  --> $DIR/needless_pass_by_value.rs:149:20
+  --> $DIR/needless_pass_by_value.rs:148:20
    |
 LL | fn more_fun(_item: impl Club<'static, i32>) {}
    |                    ^^^^^^^^^^^^^^^^^^^^^^^ help: consider taking a reference instead: `&impl Club<'static, i32>`
diff --git a/src/tools/clippy/tests/ui/needless_return.fixed b/src/tools/clippy/tests/ui/needless_return.fixed
index 5c4fd466c04..37efa6274df 100644
--- a/src/tools/clippy/tests/ui/needless_return.fixed
+++ b/src/tools/clippy/tests/ui/needless_return.fixed
@@ -1,13 +1,9 @@
 // run-rustfix
 // edition:2018
 
+#![feature(let_else)]
 #![allow(unused)]
-#![allow(
-    clippy::if_same_then_else,
-    clippy::single_match,
-    clippy::branches_sharing_code,
-    clippy::needless_bool
-)]
+#![allow(clippy::if_same_then_else, clippy::single_match, clippy::needless_bool)]
 #![warn(clippy::needless_return)]
 
 macro_rules! the_answer {
@@ -207,4 +203,8 @@ async fn async_test_return_in_macro() {
     needed_return!(0);
 }
 
+fn let_else() {
+    let Some(1) = Some(1) else { return };
+}
+
 fn main() {}
diff --git a/src/tools/clippy/tests/ui/needless_return.rs b/src/tools/clippy/tests/ui/needless_return.rs
index 34811db7413..cbf384ac9e4 100644
--- a/src/tools/clippy/tests/ui/needless_return.rs
+++ b/src/tools/clippy/tests/ui/needless_return.rs
@@ -1,13 +1,9 @@
 // run-rustfix
 // edition:2018
 
+#![feature(let_else)]
 #![allow(unused)]
-#![allow(
-    clippy::if_same_then_else,
-    clippy::single_match,
-    clippy::branches_sharing_code,
-    clippy::needless_bool
-)]
+#![allow(clippy::if_same_then_else, clippy::single_match, clippy::needless_bool)]
 #![warn(clippy::needless_return)]
 
 macro_rules! the_answer {
@@ -207,4 +203,8 @@ async fn async_test_return_in_macro() {
     needed_return!(0);
 }
 
+fn let_else() {
+    let Some(1) = Some(1) else { return };
+}
+
 fn main() {}
diff --git a/src/tools/clippy/tests/ui/needless_return.stderr b/src/tools/clippy/tests/ui/needless_return.stderr
index 74dda971fda..7ce7028bbae 100644
--- a/src/tools/clippy/tests/ui/needless_return.stderr
+++ b/src/tools/clippy/tests/ui/needless_return.stderr
@@ -1,5 +1,5 @@
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:24:5
+  --> $DIR/needless_return.rs:20:5
    |
 LL |     return true;
    |     ^^^^^^^^^^^^ help: remove `return`: `true`
@@ -7,187 +7,187 @@ LL |     return true;
    = note: `-D clippy::needless-return` implied by `-D warnings`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:28:5
+  --> $DIR/needless_return.rs:24:5
    |
 LL |     return true;
    |     ^^^^^^^^^^^^ help: remove `return`: `true`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:33:9
+  --> $DIR/needless_return.rs:29:9
    |
 LL |         return true;
    |         ^^^^^^^^^^^^ help: remove `return`: `true`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:35:9
+  --> $DIR/needless_return.rs:31:9
    |
 LL |         return false;
    |         ^^^^^^^^^^^^^ help: remove `return`: `false`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:41:17
+  --> $DIR/needless_return.rs:37:17
    |
 LL |         true => return false,
    |                 ^^^^^^^^^^^^ help: remove `return`: `false`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:43:13
+  --> $DIR/needless_return.rs:39:13
    |
 LL |             return true;
    |             ^^^^^^^^^^^^ help: remove `return`: `true`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:50:9
+  --> $DIR/needless_return.rs:46:9
    |
 LL |         return true;
    |         ^^^^^^^^^^^^ help: remove `return`: `true`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:52:16
+  --> $DIR/needless_return.rs:48:16
    |
 LL |     let _ = || return true;
    |                ^^^^^^^^^^^ help: remove `return`: `true`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:60:5
+  --> $DIR/needless_return.rs:56:5
    |
 LL |     return;
    |     ^^^^^^^ help: remove `return`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:65:9
+  --> $DIR/needless_return.rs:61:9
    |
 LL |         return;
    |         ^^^^^^^ help: remove `return`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:67:9
+  --> $DIR/needless_return.rs:63:9
    |
 LL |         return;
    |         ^^^^^^^ help: remove `return`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:74:14
+  --> $DIR/needless_return.rs:70:14
    |
 LL |         _ => return,
    |              ^^^^^^ help: replace `return` with an empty block: `{}`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:89:9
+  --> $DIR/needless_return.rs:85:9
    |
 LL |         return String::from("test");
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove `return`: `String::from("test")`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:91:9
+  --> $DIR/needless_return.rs:87:9
    |
 LL |         return String::new();
    |         ^^^^^^^^^^^^^^^^^^^^^ help: remove `return`: `String::new()`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:112:32
+  --> $DIR/needless_return.rs:108:32
    |
 LL |         bar.unwrap_or_else(|_| return)
    |                                ^^^^^^ help: replace `return` with an empty block: `{}`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:117:13
+  --> $DIR/needless_return.rs:113:13
    |
 LL |             return;
    |             ^^^^^^^ help: remove `return`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:119:20
+  --> $DIR/needless_return.rs:115:20
    |
 LL |         let _ = || return;
    |                    ^^^^^^ help: replace `return` with an empty block: `{}`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:125:32
+  --> $DIR/needless_return.rs:121:32
    |
 LL |         res.unwrap_or_else(|_| return Foo)
    |                                ^^^^^^^^^^ help: remove `return`: `Foo`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:134:5
+  --> $DIR/needless_return.rs:130:5
    |
 LL |     return true;
    |     ^^^^^^^^^^^^ help: remove `return`: `true`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:138:5
+  --> $DIR/needless_return.rs:134:5
    |
 LL |     return true;
    |     ^^^^^^^^^^^^ help: remove `return`: `true`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:143:9
+  --> $DIR/needless_return.rs:139:9
    |
 LL |         return true;
    |         ^^^^^^^^^^^^ help: remove `return`: `true`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:145:9
+  --> $DIR/needless_return.rs:141:9
    |
 LL |         return false;
    |         ^^^^^^^^^^^^^ help: remove `return`: `false`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:151:17
+  --> $DIR/needless_return.rs:147:17
    |
 LL |         true => return false,
    |                 ^^^^^^^^^^^^ help: remove `return`: `false`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:153:13
+  --> $DIR/needless_return.rs:149:13
    |
 LL |             return true;
    |             ^^^^^^^^^^^^ help: remove `return`: `true`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:160:9
+  --> $DIR/needless_return.rs:156:9
    |
 LL |         return true;
    |         ^^^^^^^^^^^^ help: remove `return`: `true`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:162:16
+  --> $DIR/needless_return.rs:158:16
    |
 LL |     let _ = || return true;
    |                ^^^^^^^^^^^ help: remove `return`: `true`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:170:5
+  --> $DIR/needless_return.rs:166:5
    |
 LL |     return;
    |     ^^^^^^^ help: remove `return`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:175:9
+  --> $DIR/needless_return.rs:171:9
    |
 LL |         return;
    |         ^^^^^^^ help: remove `return`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:177:9
+  --> $DIR/needless_return.rs:173:9
    |
 LL |         return;
    |         ^^^^^^^ help: remove `return`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:184:14
+  --> $DIR/needless_return.rs:180:14
    |
 LL |         _ => return,
    |              ^^^^^^ help: replace `return` with an empty block: `{}`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:199:9
+  --> $DIR/needless_return.rs:195:9
    |
 LL |         return String::from("test");
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove `return`: `String::from("test")`
 
 error: unneeded `return` statement
-  --> $DIR/needless_return.rs:201:9
+  --> $DIR/needless_return.rs:197:9
    |
 LL |         return String::new();
    |         ^^^^^^^^^^^^^^^^^^^^^ help: remove `return`: `String::new()`
diff --git a/src/tools/clippy/tests/ui/nonminimal_bool.rs b/src/tools/clippy/tests/ui/nonminimal_bool.rs
index 971be26278f..fa5743c1155 100644
--- a/src/tools/clippy/tests/ui/nonminimal_bool.rs
+++ b/src/tools/clippy/tests/ui/nonminimal_bool.rs
@@ -1,4 +1,4 @@
-#![allow(unused, clippy::many_single_char_names, clippy::diverging_sub_expression)]
+#![allow(unused, clippy::diverging_sub_expression)]
 #![warn(clippy::nonminimal_bool)]
 
 fn main() {
diff --git a/src/tools/clippy/tests/ui/nonminimal_bool_methods.rs b/src/tools/clippy/tests/ui/nonminimal_bool_methods.rs
index 90758740290..d0a289b7ea4 100644
--- a/src/tools/clippy/tests/ui/nonminimal_bool_methods.rs
+++ b/src/tools/clippy/tests/ui/nonminimal_bool_methods.rs
@@ -1,4 +1,4 @@
-#![allow(unused, clippy::many_single_char_names, clippy::diverging_sub_expression)]
+#![allow(unused, clippy::diverging_sub_expression)]
 #![warn(clippy::nonminimal_bool)]
 
 fn methods_with_negation() {
diff --git a/src/tools/clippy/tests/ui/op_ref.rs b/src/tools/clippy/tests/ui/op_ref.rs
index 6605c967c8e..ab9c4d34c88 100644
--- a/src/tools/clippy/tests/ui/op_ref.rs
+++ b/src/tools/clippy/tests/ui/op_ref.rs
@@ -1,6 +1,5 @@
 #![allow(unused_variables, clippy::blacklisted_name)]
 #![warn(clippy::op_ref)]
-#![allow(clippy::many_single_char_names)]
 use std::collections::HashSet;
 use std::ops::BitAnd;
 
diff --git a/src/tools/clippy/tests/ui/op_ref.stderr b/src/tools/clippy/tests/ui/op_ref.stderr
index 821099d8779..992417084bd 100644
--- a/src/tools/clippy/tests/ui/op_ref.stderr
+++ b/src/tools/clippy/tests/ui/op_ref.stderr
@@ -1,5 +1,5 @@
 error: needlessly taken reference of both operands
-  --> $DIR/op_ref.rs:12:15
+  --> $DIR/op_ref.rs:11:15
    |
 LL |     let foo = &5 - &6;
    |               ^^^^^^^
@@ -11,7 +11,7 @@ LL |     let foo = 5 - 6;
    |               ~   ~
 
 error: taken reference of right operand
-  --> $DIR/op_ref.rs:57:13
+  --> $DIR/op_ref.rs:56:13
    |
 LL |     let z = x & &y;
    |             ^^^^--
diff --git a/src/tools/clippy/tests/ui/overflow_check_conditional.rs b/src/tools/clippy/tests/ui/overflow_check_conditional.rs
index 84332040dba..5db75f5291b 100644
--- a/src/tools/clippy/tests/ui/overflow_check_conditional.rs
+++ b/src/tools/clippy/tests/ui/overflow_check_conditional.rs
@@ -1,4 +1,3 @@
-#![allow(clippy::many_single_char_names)]
 #![warn(clippy::overflow_check_conditional)]
 
 fn main() {
diff --git a/src/tools/clippy/tests/ui/overflow_check_conditional.stderr b/src/tools/clippy/tests/ui/overflow_check_conditional.stderr
index 19e843c2c0a..1b8b146b60a 100644
--- a/src/tools/clippy/tests/ui/overflow_check_conditional.stderr
+++ b/src/tools/clippy/tests/ui/overflow_check_conditional.stderr
@@ -1,5 +1,5 @@
 error: you are trying to use classic C overflow conditions that will fail in Rust
-  --> $DIR/overflow_check_conditional.rs:8:8
+  --> $DIR/overflow_check_conditional.rs:7:8
    |
 LL |     if a + b < a {}
    |        ^^^^^^^^^
@@ -7,43 +7,43 @@ LL |     if a + b < a {}
    = note: `-D clippy::overflow-check-conditional` implied by `-D warnings`
 
 error: you are trying to use classic C overflow conditions that will fail in Rust
-  --> $DIR/overflow_check_conditional.rs:9:8
+  --> $DIR/overflow_check_conditional.rs:8:8
    |
 LL |     if a > a + b {}
    |        ^^^^^^^^^
 
 error: you are trying to use classic C overflow conditions that will fail in Rust
-  --> $DIR/overflow_check_conditional.rs:10:8
+  --> $DIR/overflow_check_conditional.rs:9:8
    |
 LL |     if a + b < b {}
    |        ^^^^^^^^^
 
 error: you are trying to use classic C overflow conditions that will fail in Rust
-  --> $DIR/overflow_check_conditional.rs:11:8
+  --> $DIR/overflow_check_conditional.rs:10:8
    |
 LL |     if b > a + b {}
    |        ^^^^^^^^^
 
 error: you are trying to use classic C underflow conditions that will fail in Rust
-  --> $DIR/overflow_check_conditional.rs:12:8
+  --> $DIR/overflow_check_conditional.rs:11:8
    |
 LL |     if a - b > b {}
    |        ^^^^^^^^^
 
 error: you are trying to use classic C underflow conditions that will fail in Rust
-  --> $DIR/overflow_check_conditional.rs:13:8
+  --> $DIR/overflow_check_conditional.rs:12:8
    |
 LL |     if b < a - b {}
    |        ^^^^^^^^^
 
 error: you are trying to use classic C underflow conditions that will fail in Rust
-  --> $DIR/overflow_check_conditional.rs:14:8
+  --> $DIR/overflow_check_conditional.rs:13:8
    |
 LL |     if a - b > a {}
    |        ^^^^^^^^^
 
 error: you are trying to use classic C underflow conditions that will fail in Rust
-  --> $DIR/overflow_check_conditional.rs:15:8
+  --> $DIR/overflow_check_conditional.rs:14:8
    |
 LL |     if a < a - b {}
    |        ^^^^^^^^^
diff --git a/src/tools/clippy/tests/ui/ptr_arg.rs b/src/tools/clippy/tests/ui/ptr_arg.rs
index 06370dfce65..99e6d2aad8d 100644
--- a/src/tools/clippy/tests/ui/ptr_arg.rs
+++ b/src/tools/clippy/tests/ui/ptr_arg.rs
@@ -1,4 +1,9 @@
-#![allow(unused, clippy::many_single_char_names, clippy::redundant_clone)]
+#![allow(
+    unused,
+    clippy::many_single_char_names,
+    clippy::redundant_clone,
+    clippy::if_then_panic
+)]
 #![warn(clippy::ptr_arg)]
 
 use std::borrow::Cow;
diff --git a/src/tools/clippy/tests/ui/ptr_arg.stderr b/src/tools/clippy/tests/ui/ptr_arg.stderr
index 64594eb870c..42183447ead 100644
--- a/src/tools/clippy/tests/ui/ptr_arg.stderr
+++ b/src/tools/clippy/tests/ui/ptr_arg.stderr
@@ -1,5 +1,5 @@
 error: writing `&Vec<_>` instead of `&[_]` involves one more reference and cannot be used with non-Vec-based slices
-  --> $DIR/ptr_arg.rs:7:14
+  --> $DIR/ptr_arg.rs:12:14
    |
 LL | fn do_vec(x: &Vec<i64>) {
    |              ^^^^^^^^^ help: change this to: `&[i64]`
@@ -7,25 +7,25 @@ LL | fn do_vec(x: &Vec<i64>) {
    = note: `-D clippy::ptr-arg` implied by `-D warnings`
 
 error: writing `&String` instead of `&str` involves a new object where a slice will do
-  --> $DIR/ptr_arg.rs:16:14
+  --> $DIR/ptr_arg.rs:21:14
    |
 LL | fn do_str(x: &String) {
    |              ^^^^^^^ help: change this to: `&str`
 
 error: writing `&PathBuf` instead of `&Path` involves a new object where a slice will do
-  --> $DIR/ptr_arg.rs:25:15
+  --> $DIR/ptr_arg.rs:30:15
    |
 LL | fn do_path(x: &PathBuf) {
    |               ^^^^^^^^ help: change this to: `&Path`
 
 error: writing `&Vec<_>` instead of `&[_]` involves one more reference and cannot be used with non-Vec-based slices
-  --> $DIR/ptr_arg.rs:38:18
+  --> $DIR/ptr_arg.rs:43:18
    |
 LL |     fn do_vec(x: &Vec<i64>);
    |                  ^^^^^^^^^ help: change this to: `&[i64]`
 
 error: writing `&Vec<_>` instead of `&[_]` involves one more reference and cannot be used with non-Vec-based slices
-  --> $DIR/ptr_arg.rs:51:14
+  --> $DIR/ptr_arg.rs:56:14
    |
 LL | fn cloned(x: &Vec<u8>) -> Vec<u8> {
    |              ^^^^^^^^
@@ -44,7 +44,7 @@ LL |     x.to_owned()
    |
 
 error: writing `&String` instead of `&str` involves a new object where a slice will do
-  --> $DIR/ptr_arg.rs:60:18
+  --> $DIR/ptr_arg.rs:65:18
    |
 LL | fn str_cloned(x: &String) -> String {
    |                  ^^^^^^^
@@ -67,7 +67,7 @@ LL |     x.to_string()
    |
 
 error: writing `&PathBuf` instead of `&Path` involves a new object where a slice will do
-  --> $DIR/ptr_arg.rs:68:19
+  --> $DIR/ptr_arg.rs:73:19
    |
 LL | fn path_cloned(x: &PathBuf) -> PathBuf {
    |                   ^^^^^^^^
@@ -90,7 +90,7 @@ LL |     x.to_path_buf()
    |
 
 error: writing `&String` instead of `&str` involves a new object where a slice will do
-  --> $DIR/ptr_arg.rs:76:44
+  --> $DIR/ptr_arg.rs:81:44
    |
 LL | fn false_positive_capacity(x: &Vec<u8>, y: &String) {
    |                                            ^^^^^^^
@@ -109,13 +109,13 @@ LL |     let c = y;
    |             ~
 
 error: using a reference to `Cow` is not recommended
-  --> $DIR/ptr_arg.rs:90:25
+  --> $DIR/ptr_arg.rs:95:25
    |
 LL | fn test_cow_with_ref(c: &Cow<[i32]>) {}
    |                         ^^^^^^^^^^^ help: change this to: `&[i32]`
 
 error: writing `&Vec<_>` instead of `&[_]` involves one more reference and cannot be used with non-Vec-based slices
-  --> $DIR/ptr_arg.rs:143:21
+  --> $DIR/ptr_arg.rs:148:21
    |
 LL |     fn foo_vec(vec: &Vec<u8>) {
    |                     ^^^^^^^^
@@ -134,7 +134,7 @@ LL |         let _ = vec.to_owned().clone();
    |                 ~~~~~~~~~~~~~~
 
 error: writing `&PathBuf` instead of `&Path` involves a new object where a slice will do
-  --> $DIR/ptr_arg.rs:148:23
+  --> $DIR/ptr_arg.rs:153:23
    |
 LL |     fn foo_path(path: &PathBuf) {
    |                       ^^^^^^^^
@@ -153,7 +153,7 @@ LL |         let _ = path.to_path_buf().clone();
    |                 ~~~~~~~~~~~~~~~~~~
 
 error: writing `&PathBuf` instead of `&Path` involves a new object where a slice will do
-  --> $DIR/ptr_arg.rs:153:21
+  --> $DIR/ptr_arg.rs:158:21
    |
 LL |     fn foo_str(str: &PathBuf) {
    |                     ^^^^^^^^
diff --git a/src/tools/clippy/tests/ui/repeat_once.fixed b/src/tools/clippy/tests/ui/repeat_once.fixed
index a637c22fbcd..dc197e50300 100644
--- a/src/tools/clippy/tests/ui/repeat_once.fixed
+++ b/src/tools/clippy/tests/ui/repeat_once.fixed
@@ -1,6 +1,6 @@
 // run-rustfix
 #![warn(clippy::repeat_once)]
-#[allow(unused, clippy::many_single_char_names, clippy::redundant_clone)]
+#[allow(unused, clippy::redundant_clone)]
 fn main() {
     const N: usize = 1;
     let s = "str";
diff --git a/src/tools/clippy/tests/ui/repeat_once.rs b/src/tools/clippy/tests/ui/repeat_once.rs
index d99ca1b5b55..0ec5127117c 100644
--- a/src/tools/clippy/tests/ui/repeat_once.rs
+++ b/src/tools/clippy/tests/ui/repeat_once.rs
@@ -1,6 +1,6 @@
 // run-rustfix
 #![warn(clippy::repeat_once)]
-#[allow(unused, clippy::many_single_char_names, clippy::redundant_clone)]
+#[allow(unused, clippy::redundant_clone)]
 fn main() {
     const N: usize = 1;
     let s = "str";
diff --git a/src/tools/clippy/tests/ui/same_name_method.rs b/src/tools/clippy/tests/ui/same_name_method.rs
new file mode 100644
index 00000000000..12e10ba6c49
--- /dev/null
+++ b/src/tools/clippy/tests/ui/same_name_method.rs
@@ -0,0 +1,111 @@
+#![warn(clippy::same_name_method)]
+#![allow(dead_code, non_camel_case_types)]
+
+trait T1 {
+    fn foo() {}
+}
+
+trait T2 {
+    fn foo() {}
+}
+
+mod should_lint {
+
+    mod test_basic_case {
+        use crate::T1;
+
+        struct S;
+
+        impl S {
+            fn foo() {}
+        }
+
+        impl T1 for S {
+            fn foo() {}
+        }
+    }
+
+    mod test_derive {
+
+        #[derive(Clone)]
+        struct S;
+
+        impl S {
+            fn clone() {}
+        }
+    }
+
+    mod with_generic {
+        use crate::T1;
+
+        struct S<U>(U);
+
+        impl<U> S<U> {
+            fn foo() {}
+        }
+
+        impl<U: Copy> T1 for S<U> {
+            fn foo() {}
+        }
+    }
+
+    mod default_method {
+        use crate::T1;
+
+        struct S;
+
+        impl S {
+            fn foo() {}
+        }
+
+        impl T1 for S {}
+    }
+
+    mod mulitply_conflicit_trait {
+        use crate::{T1, T2};
+
+        struct S;
+
+        impl S {
+            fn foo() {}
+        }
+
+        impl T1 for S {}
+
+        impl T2 for S {}
+    }
+}
+
+mod should_not_lint {
+
+    mod not_lint_two_trait_method {
+        use crate::{T1, T2};
+
+        struct S;
+
+        impl T1 for S {
+            fn foo() {}
+        }
+
+        impl T2 for S {
+            fn foo() {}
+        }
+    }
+
+    mod only_lint_on_method {
+        trait T3 {
+            type foo;
+        }
+
+        struct S;
+
+        impl S {
+            fn foo() {}
+        }
+        impl T3 for S {
+            type foo = usize;
+        }
+    }
+}
+
+fn main() {}
diff --git a/src/tools/clippy/tests/ui/same_name_method.stderr b/src/tools/clippy/tests/ui/same_name_method.stderr
new file mode 100644
index 00000000000..0f9139b41b9
--- /dev/null
+++ b/src/tools/clippy/tests/ui/same_name_method.stderr
@@ -0,0 +1,64 @@
+error: method's name is same to an existing method in a trait
+  --> $DIR/same_name_method.rs:20:13
+   |
+LL |             fn foo() {}
+   |             ^^^^^^^^^^^
+   |
+   = note: `-D clippy::same-name-method` implied by `-D warnings`
+note: existing `foo` defined here
+  --> $DIR/same_name_method.rs:24:13
+   |
+LL |             fn foo() {}
+   |             ^^^^^^^^^^^
+
+error: method's name is same to an existing method in a trait
+  --> $DIR/same_name_method.rs:44:13
+   |
+LL |             fn foo() {}
+   |             ^^^^^^^^^^^
+   |
+note: existing `foo` defined here
+  --> $DIR/same_name_method.rs:48:13
+   |
+LL |             fn foo() {}
+   |             ^^^^^^^^^^^
+
+error: method's name is same to an existing method in a trait
+  --> $DIR/same_name_method.rs:58:13
+   |
+LL |             fn foo() {}
+   |             ^^^^^^^^^^^
+   |
+note: existing `foo` defined here
+  --> $DIR/same_name_method.rs:61:9
+   |
+LL |         impl T1 for S {}
+   |         ^^^^^^^^^^^^^^^^
+
+error: method's name is same to an existing method in a trait
+  --> $DIR/same_name_method.rs:70:13
+   |
+LL |             fn foo() {}
+   |             ^^^^^^^^^^^
+   |
+note: existing `foo` defined here
+  --> $DIR/same_name_method.rs:73:9
+   |
+LL |         impl T1 for S {}
+   |         ^^^^^^^^^^^^^^^^
+
+error: method's name is same to an existing method in a trait
+  --> $DIR/same_name_method.rs:34:13
+   |
+LL |             fn clone() {}
+   |             ^^^^^^^^^^^^^
+   |
+note: existing `clone` defined here
+  --> $DIR/same_name_method.rs:30:18
+   |
+LL |         #[derive(Clone)]
+   |                  ^^^^^
+   = note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 5 previous errors
+
diff --git a/src/tools/clippy/tests/ui/semicolon_if_nothing_returned.rs b/src/tools/clippy/tests/ui/semicolon_if_nothing_returned.rs
index 79ba7402f1f..9644a232968 100644
--- a/src/tools/clippy/tests/ui/semicolon_if_nothing_returned.rs
+++ b/src/tools/clippy/tests/ui/semicolon_if_nothing_returned.rs
@@ -1,4 +1,5 @@
 #![warn(clippy::semicolon_if_nothing_returned)]
+#![allow(clippy::redundant_closure)]
 #![feature(label_break_value)]
 
 fn get_unit() {}
@@ -30,8 +31,8 @@ fn unsafe_checks_error() {
     use std::ptr;
 
     let mut s = MaybeUninit::<String>::uninit();
-    let _d = || unsafe { 
-        ptr::drop_in_place(s.as_mut_ptr()) 
+    let _d = || unsafe {
+        ptr::drop_in_place(s.as_mut_ptr())
     };
 }
 
diff --git a/src/tools/clippy/tests/ui/semicolon_if_nothing_returned.stderr b/src/tools/clippy/tests/ui/semicolon_if_nothing_returned.stderr
index e88ebe2ad35..78813e7cc1c 100644
--- a/src/tools/clippy/tests/ui/semicolon_if_nothing_returned.stderr
+++ b/src/tools/clippy/tests/ui/semicolon_if_nothing_returned.stderr
@@ -1,5 +1,5 @@
 error: consider adding a `;` to the last statement for consistent formatting
-  --> $DIR/semicolon_if_nothing_returned.rs:8:5
+  --> $DIR/semicolon_if_nothing_returned.rs:9:5
    |
 LL |     println!("Hello")
    |     ^^^^^^^^^^^^^^^^^ help: add a `;` here: `println!("Hello");`
@@ -7,27 +7,27 @@ LL |     println!("Hello")
    = note: `-D clippy::semicolon-if-nothing-returned` implied by `-D warnings`
 
 error: consider adding a `;` to the last statement for consistent formatting
-  --> $DIR/semicolon_if_nothing_returned.rs:12:5
+  --> $DIR/semicolon_if_nothing_returned.rs:13:5
    |
 LL |     get_unit()
    |     ^^^^^^^^^^ help: add a `;` here: `get_unit();`
 
 error: consider adding a `;` to the last statement for consistent formatting
-  --> $DIR/semicolon_if_nothing_returned.rs:17:5
+  --> $DIR/semicolon_if_nothing_returned.rs:18:5
    |
 LL |     y = x + 1
    |     ^^^^^^^^^ help: add a `;` here: `y = x + 1;`
 
 error: consider adding a `;` to the last statement for consistent formatting
-  --> $DIR/semicolon_if_nothing_returned.rs:23:9
+  --> $DIR/semicolon_if_nothing_returned.rs:24:9
    |
 LL |         hello()
    |         ^^^^^^^ help: add a `;` here: `hello();`
 
 error: consider adding a `;` to the last statement for consistent formatting
-  --> $DIR/semicolon_if_nothing_returned.rs:34:9
+  --> $DIR/semicolon_if_nothing_returned.rs:35:9
    |
-LL |         ptr::drop_in_place(s.as_mut_ptr()) 
+LL |         ptr::drop_in_place(s.as_mut_ptr())
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add a `;` here: `ptr::drop_in_place(s.as_mut_ptr());`
 
 error: aborting due to 5 previous errors
diff --git a/src/tools/clippy/tests/ui/suspicious_else_formatting.rs b/src/tools/clippy/tests/ui/suspicious_else_formatting.rs
index 547615b10d9..be8bc22bf98 100644
--- a/src/tools/clippy/tests/ui/suspicious_else_formatting.rs
+++ b/src/tools/clippy/tests/ui/suspicious_else_formatting.rs
@@ -1,5 +1,10 @@
+// aux-build:proc_macro_suspicious_else_formatting.rs
+
 #![warn(clippy::suspicious_else_formatting)]
 
+extern crate proc_macro_suspicious_else_formatting;
+use proc_macro_suspicious_else_formatting::DeriveBadSpan;
+
 fn foo() -> bool {
     true
 }
@@ -103,3 +108,7 @@ fn main() {
     {
     }
 }
+
+// #7650 - Don't lint. Proc-macro using bad spans for `if` expressions.
+#[derive(DeriveBadSpan)]
+struct _Foo(u32, u32);
diff --git a/src/tools/clippy/tests/ui/suspicious_else_formatting.stderr b/src/tools/clippy/tests/ui/suspicious_else_formatting.stderr
index d8d67b4138a..d1db195cbb8 100644
--- a/src/tools/clippy/tests/ui/suspicious_else_formatting.stderr
+++ b/src/tools/clippy/tests/ui/suspicious_else_formatting.stderr
@@ -1,5 +1,5 @@
 error: this looks like an `else {..}` but the `else` is missing
-  --> $DIR/suspicious_else_formatting.rs:11:6
+  --> $DIR/suspicious_else_formatting.rs:16:6
    |
 LL |     } {
    |      ^
@@ -8,7 +8,7 @@ LL |     } {
    = note: to remove this lint, add the missing `else` or add a new line before the next block
 
 error: this looks like an `else if` but the `else` is missing
-  --> $DIR/suspicious_else_formatting.rs:15:6
+  --> $DIR/suspicious_else_formatting.rs:20:6
    |
 LL |     } if foo() {
    |      ^
@@ -16,7 +16,7 @@ LL |     } if foo() {
    = note: to remove this lint, add the missing `else` or add a new line before the second `if`
 
 error: this looks like an `else if` but the `else` is missing
-  --> $DIR/suspicious_else_formatting.rs:22:10
+  --> $DIR/suspicious_else_formatting.rs:27:10
    |
 LL |         } if foo() {
    |          ^
@@ -24,7 +24,7 @@ LL |         } if foo() {
    = note: to remove this lint, add the missing `else` or add a new line before the second `if`
 
 error: this looks like an `else if` but the `else` is missing
-  --> $DIR/suspicious_else_formatting.rs:30:10
+  --> $DIR/suspicious_else_formatting.rs:35:10
    |
 LL |         } if foo() {
    |          ^
@@ -32,7 +32,7 @@ LL |         } if foo() {
    = note: to remove this lint, add the missing `else` or add a new line before the second `if`
 
 error: this is an `else {..}` but the formatting might hide it
-  --> $DIR/suspicious_else_formatting.rs:39:6
+  --> $DIR/suspicious_else_formatting.rs:44:6
    |
 LL |       } else
    |  ______^
@@ -42,7 +42,7 @@ LL | |     {
    = note: to remove this lint, remove the `else` or remove the new line between `else` and `{..}`
 
 error: this is an `else if` but the formatting might hide it
-  --> $DIR/suspicious_else_formatting.rs:51:6
+  --> $DIR/suspicious_else_formatting.rs:56:6
    |
 LL |       } else
    |  ______^
@@ -52,7 +52,7 @@ LL | |     if foo() { // the span of the above error should continue here
    = note: to remove this lint, remove the `else` or remove the new line between `else` and `if`
 
 error: this is an `else if` but the formatting might hide it
-  --> $DIR/suspicious_else_formatting.rs:56:6
+  --> $DIR/suspicious_else_formatting.rs:61:6
    |
 LL |       }
    |  ______^
@@ -63,7 +63,7 @@ LL | |     if foo() { // the span of the above error should continue here
    = note: to remove this lint, remove the `else` or remove the new line between `else` and `if`
 
 error: this is an `else {..}` but the formatting might hide it
-  --> $DIR/suspicious_else_formatting.rs:83:6
+  --> $DIR/suspicious_else_formatting.rs:88:6
    |
 LL |       }
    |  ______^
@@ -75,7 +75,7 @@ LL | |     {
    = note: to remove this lint, remove the `else` or remove the new line between `else` and `{..}`
 
 error: this is an `else {..}` but the formatting might hide it
-  --> $DIR/suspicious_else_formatting.rs:91:6
+  --> $DIR/suspicious_else_formatting.rs:96:6
    |
 LL |       }
    |  ______^
diff --git a/src/tools/clippy/tests/ui/trivially_copy_pass_by_ref.rs b/src/tools/clippy/tests/ui/trivially_copy_pass_by_ref.rs
index 1a0123803a3..ea3dce17081 100644
--- a/src/tools/clippy/tests/ui/trivially_copy_pass_by_ref.rs
+++ b/src/tools/clippy/tests/ui/trivially_copy_pass_by_ref.rs
@@ -2,11 +2,7 @@
 // normalize-stderr-test "\(limit: \d+ byte\)" -> "(limit: N byte)"
 
 #![deny(clippy::trivially_copy_pass_by_ref)]
-#![allow(
-    clippy::many_single_char_names,
-    clippy::blacklisted_name,
-    clippy::redundant_field_names
-)]
+#![allow(clippy::blacklisted_name, clippy::redundant_field_names)]
 
 #[derive(Copy, Clone)]
 struct Foo(u32);
diff --git a/src/tools/clippy/tests/ui/trivially_copy_pass_by_ref.stderr b/src/tools/clippy/tests/ui/trivially_copy_pass_by_ref.stderr
index 9c4c49ceac4..a88d35f3ea5 100644
--- a/src/tools/clippy/tests/ui/trivially_copy_pass_by_ref.stderr
+++ b/src/tools/clippy/tests/ui/trivially_copy_pass_by_ref.stderr
@@ -1,5 +1,5 @@
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:51:11
+  --> $DIR/trivially_copy_pass_by_ref.rs:47:11
    |
 LL | fn bad(x: &u32, y: &Foo, z: &Baz) {}
    |           ^^^^ help: consider passing by value instead: `u32`
@@ -11,97 +11,97 @@ LL | #![deny(clippy::trivially_copy_pass_by_ref)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:51:20
+  --> $DIR/trivially_copy_pass_by_ref.rs:47:20
    |
 LL | fn bad(x: &u32, y: &Foo, z: &Baz) {}
    |                    ^^^^ help: consider passing by value instead: `Foo`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:51:29
+  --> $DIR/trivially_copy_pass_by_ref.rs:47:29
    |
 LL | fn bad(x: &u32, y: &Foo, z: &Baz) {}
    |                             ^^^^ help: consider passing by value instead: `Baz`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:58:12
+  --> $DIR/trivially_copy_pass_by_ref.rs:54:12
    |
 LL |     fn bad(&self, x: &u32, y: &Foo, z: &Baz) {}
    |            ^^^^^ help: consider passing by value instead: `self`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:58:22
+  --> $DIR/trivially_copy_pass_by_ref.rs:54:22
    |
 LL |     fn bad(&self, x: &u32, y: &Foo, z: &Baz) {}
    |                      ^^^^ help: consider passing by value instead: `u32`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:58:31
+  --> $DIR/trivially_copy_pass_by_ref.rs:54:31
    |
 LL |     fn bad(&self, x: &u32, y: &Foo, z: &Baz) {}
    |                               ^^^^ help: consider passing by value instead: `Foo`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:58:40
+  --> $DIR/trivially_copy_pass_by_ref.rs:54:40
    |
 LL |     fn bad(&self, x: &u32, y: &Foo, z: &Baz) {}
    |                                        ^^^^ help: consider passing by value instead: `Baz`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:60:16
+  --> $DIR/trivially_copy_pass_by_ref.rs:56:16
    |
 LL |     fn bad2(x: &u32, y: &Foo, z: &Baz) {}
    |                ^^^^ help: consider passing by value instead: `u32`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:60:25
+  --> $DIR/trivially_copy_pass_by_ref.rs:56:25
    |
 LL |     fn bad2(x: &u32, y: &Foo, z: &Baz) {}
    |                         ^^^^ help: consider passing by value instead: `Foo`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:60:34
+  --> $DIR/trivially_copy_pass_by_ref.rs:56:34
    |
 LL |     fn bad2(x: &u32, y: &Foo, z: &Baz) {}
    |                                  ^^^^ help: consider passing by value instead: `Baz`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:62:35
+  --> $DIR/trivially_copy_pass_by_ref.rs:58:35
    |
 LL |     fn bad_issue7518(self, other: &Self) {}
    |                                   ^^^^^ help: consider passing by value instead: `Self`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:74:16
+  --> $DIR/trivially_copy_pass_by_ref.rs:70:16
    |
 LL |     fn bad2(x: &u32, y: &Foo, z: &Baz) {}
    |                ^^^^ help: consider passing by value instead: `u32`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:74:25
+  --> $DIR/trivially_copy_pass_by_ref.rs:70:25
    |
 LL |     fn bad2(x: &u32, y: &Foo, z: &Baz) {}
    |                         ^^^^ help: consider passing by value instead: `Foo`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:74:34
+  --> $DIR/trivially_copy_pass_by_ref.rs:70:34
    |
 LL |     fn bad2(x: &u32, y: &Foo, z: &Baz) {}
    |                                  ^^^^ help: consider passing by value instead: `Baz`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:78:34
+  --> $DIR/trivially_copy_pass_by_ref.rs:74:34
    |
 LL |     fn trait_method(&self, _foo: &Foo);
    |                                  ^^^^ help: consider passing by value instead: `Foo`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:110:21
+  --> $DIR/trivially_copy_pass_by_ref.rs:106:21
    |
 LL |     fn foo_never(x: &i32) {
    |                     ^^^^ help: consider passing by value instead: `i32`
 
 error: this argument (N byte) is passed by reference, but would be more efficient if passed by value (limit: N byte)
-  --> $DIR/trivially_copy_pass_by_ref.rs:115:15
+  --> $DIR/trivially_copy_pass_by_ref.rs:111:15
    |
 LL |     fn foo(x: &i32) {
    |               ^^^^ help: consider passing by value instead: `i32`
diff --git a/src/tools/clippy/tests/ui/while_let_on_iterator.fixed b/src/tools/clippy/tests/ui/while_let_on_iterator.fixed
index cdcdd808c94..f5a34190902 100644
--- a/src/tools/clippy/tests/ui/while_let_on_iterator.fixed
+++ b/src/tools/clippy/tests/ui/while_let_on_iterator.fixed
@@ -188,7 +188,7 @@ fn issue6491() {
     // Used in outer loop, needs &mut
     let mut it = 1..40;
     while let Some(n) = it.next() {
-        for m in &mut it {
+        for m in it.by_ref() {
             if m % 10 == 0 {
                 break;
             }
@@ -219,7 +219,7 @@ fn issue6491() {
 
         // Used after the loop, needs &mut.
         let mut it = 1..40;
-        for m in &mut it {
+        for m in it.by_ref() {
             if m % 10 == 0 {
                 break;
             }
@@ -236,7 +236,7 @@ fn issue6231() {
     let mut it = 1..40;
     let mut opt = Some(0);
     while let Some(n) = opt.take().or_else(|| it.next()) {
-        for m in &mut it {
+        for m in it.by_ref() {
             if n % 10 == 0 {
                 break;
             }
@@ -251,7 +251,7 @@ fn issue1924() {
     impl<T: Iterator<Item = u32>> S<T> {
         fn f(&mut self) -> Option<u32> {
             // Used as a field.
-            for i in &mut self.0 {
+            for i in self.0.by_ref() {
                 if !(3..=7).contains(&i) {
                     return Some(i);
                 }
@@ -283,7 +283,7 @@ fn issue1924() {
                 }
             }
             // This one is fine, a different field is borrowed
-            for i in &mut self.0.0.0 {
+            for i in self.0.0.0.by_ref() {
                 if i == 1 {
                     return self.0.1.take();
                 } else {
@@ -312,7 +312,7 @@ fn issue1924() {
 
     // Needs &mut, field of the iterator is accessed after the loop
     let mut it = S2(1..40, 0);
-    for n in &mut it {
+    for n in it.by_ref() {
         if n == 0 {
             break;
         }
@@ -324,7 +324,7 @@ fn issue7249() {
     let mut it = 0..10;
     let mut x = || {
         // Needs &mut, the closure can be called multiple times
-        for x in &mut it {
+        for x in it.by_ref() {
             if x % 2 == 0 {
                 break;
             }
@@ -338,7 +338,7 @@ fn issue7510() {
     let mut it = 0..10;
     let it = &mut it;
     // Needs to reborrow `it` as the binding isn't mutable
-    for x in &mut *it {
+    for x in it.by_ref() {
         if x % 2 == 0 {
             break;
         }
@@ -349,7 +349,7 @@ fn issue7510() {
     let mut it = 0..10;
     let it = S(&mut it);
     // Needs to reborrow `it.0` as the binding isn't mutable
-    for x in &mut *it.0 {
+    for x in it.0.by_ref() {
         if x % 2 == 0 {
             break;
         }
diff --git a/src/tools/clippy/tests/ui/while_let_on_iterator.stderr b/src/tools/clippy/tests/ui/while_let_on_iterator.stderr
index ff9b08996da..5e2fce4491a 100644
--- a/src/tools/clippy/tests/ui/while_let_on_iterator.stderr
+++ b/src/tools/clippy/tests/ui/while_let_on_iterator.stderr
@@ -46,7 +46,7 @@ error: this loop could be written as a `for` loop
   --> $DIR/while_let_on_iterator.rs:191:9
    |
 LL |         while let Some(m) = it.next() {
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for m in &mut it`
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for m in it.by_ref()`
 
 error: this loop could be written as a `for` loop
   --> $DIR/while_let_on_iterator.rs:202:5
@@ -70,19 +70,19 @@ error: this loop could be written as a `for` loop
   --> $DIR/while_let_on_iterator.rs:222:9
    |
 LL |         while let Some(m) = it.next() {
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for m in &mut it`
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for m in it.by_ref()`
 
 error: this loop could be written as a `for` loop
   --> $DIR/while_let_on_iterator.rs:239:9
    |
 LL |         while let Some(m) = it.next() {
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for m in &mut it`
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for m in it.by_ref()`
 
 error: this loop could be written as a `for` loop
   --> $DIR/while_let_on_iterator.rs:254:13
    |
 LL |             while let Some(i) = self.0.next() {
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for i in &mut self.0`
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for i in self.0.by_ref()`
 
 error: manual `!RangeInclusive::contains` implementation
   --> $DIR/while_let_on_iterator.rs:255:20
@@ -96,31 +96,31 @@ error: this loop could be written as a `for` loop
   --> $DIR/while_let_on_iterator.rs:286:13
    |
 LL |             while let Some(i) = self.0.0.0.next() {
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for i in &mut self.0.0.0`
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for i in self.0.0.0.by_ref()`
 
 error: this loop could be written as a `for` loop
   --> $DIR/while_let_on_iterator.rs:315:5
    |
 LL |     while let Some(n) = it.next() {
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for n in &mut it`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for n in it.by_ref()`
 
 error: this loop could be written as a `for` loop
   --> $DIR/while_let_on_iterator.rs:327:9
    |
 LL |         while let Some(x) = it.next() {
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for x in &mut it`
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for x in it.by_ref()`
 
 error: this loop could be written as a `for` loop
   --> $DIR/while_let_on_iterator.rs:341:5
    |
 LL |     while let Some(x) = it.next() {
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for x in &mut *it`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for x in it.by_ref()`
 
 error: this loop could be written as a `for` loop
   --> $DIR/while_let_on_iterator.rs:352:5
    |
 LL |     while let Some(x) = it.0.next() {
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for x in &mut *it.0`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `for x in it.0.by_ref()`
 
 error: this loop could be written as a `for` loop
   --> $DIR/while_let_on_iterator.rs:371:5
diff --git a/src/tools/clippy/tests/ui/wrong_self_convention2.rs b/src/tools/clippy/tests/ui/wrong_self_convention2.rs
index 501bc1e6a85..0d827c1feb3 100644
--- a/src/tools/clippy/tests/ui/wrong_self_convention2.rs
+++ b/src/tools/clippy/tests/ui/wrong_self_convention2.rs
@@ -68,3 +68,40 @@ mod issue7179 {
         fn as_byte_slice(slice: &[Self]) -> &[u8];
     }
 }
+
+mod issue3414 {
+    struct CellLikeThing<T>(T);
+
+    impl<T> CellLikeThing<T> {
+        // don't trigger
+        fn into_inner(this: Self) -> T {
+            this.0
+        }
+    }
+
+    impl<T> std::ops::Deref for CellLikeThing<T> {
+        type Target = T;
+
+        fn deref(&self) -> &T {
+            &self.0
+        }
+    }
+}
+
+// don't trigger
+mod issue4546 {
+    use std::pin::Pin;
+
+    struct S;
+    impl S {
+        pub fn as_mut(self: Pin<&mut Self>) {}
+
+        pub fn as_other_thingy(self: Pin<&Self>) {}
+
+        pub fn is_other_thingy(self: Pin<&Self>) {}
+
+        pub fn to_mut(self: Pin<&mut Self>) {}
+
+        pub fn to_other_thingy(self: Pin<&Self>) {}
+    }
+}
diff --git a/src/tools/rust-analyzer b/src/tools/rust-analyzer
-Subproject f1d7f98ed07b9934286b9c4809dd4d7a4753787
+Subproject 009e6ceb1ddcd27a9ced3bcb7d0ef823379185a
diff --git a/src/tools/tidy/src/deps.rs b/src/tools/tidy/src/deps.rs
index 60703384e9e..c1719a9ffe8 100644
--- a/src/tools/tidy/src/deps.rs
+++ b/src/tools/tidy/src/deps.rs
@@ -167,6 +167,7 @@ const PERMITTED_DEPENDENCIES: &[&str] = &[
     "rand_hc",
     "rand_pcg",
     "rand_xorshift",
+    "rand_xoshiro",
     "redox_syscall",
     "regex",
     "regex-automata",
diff --git a/src/tools/tidy/src/lib.rs b/src/tools/tidy/src/lib.rs
index 35809e59926..a20ea3235ed 100644
--- a/src/tools/tidy/src/lib.rs
+++ b/src/tools/tidy/src/lib.rs
@@ -57,6 +57,7 @@ fn filter_dirs(path: &Path) -> bool {
     let skip = [
         "tidy-test-file",
         "compiler/rustc_codegen_cranelift",
+        "compiler/rustc_codegen_gcc",
         "src/llvm-project",
         "library/backtrace",
         "library/stdarch",