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-rw-r--r--compiler/rustc_codegen_cranelift/src/intrinsics/mod.rs6
-rw-r--r--compiler/rustc_codegen_gcc/src/context.rs7
-rw-r--r--compiler/rustc_codegen_gcc/src/intrinsic/mod.rs6
-rw-r--r--compiler/rustc_codegen_llvm/src/context.rs14
-rw-r--r--compiler/rustc_codegen_llvm/src/intrinsic.rs4
-rw-r--r--compiler/rustc_const_eval/src/const_eval/machine.rs5
-rw-r--r--compiler/rustc_const_eval/src/errors.rs7
-rw-r--r--compiler/rustc_const_eval/src/interpret/operand.rs6
-rw-r--r--compiler/rustc_const_eval/src/interpret/place.rs19
-rw-r--r--compiler/rustc_const_eval/src/interpret/projection.rs49
-rw-r--r--compiler/rustc_const_eval/src/util/mod.rs4
-rw-r--r--compiler/rustc_hir/src/lang_items.rs4
-rw-r--r--compiler/rustc_hir_analysis/src/check/intrinsic.rs2
-rw-r--r--compiler/rustc_hir_analysis/src/coherence/builtin.rs150
-rw-r--r--compiler/rustc_hir_analysis/src/coherence/mod.rs55
-rw-r--r--compiler/rustc_hir_analysis/src/coherence/unsafety.rs16
-rw-r--r--compiler/rustc_hir_analysis/src/lib.rs16
-rw-r--r--compiler/rustc_hir_typeck/src/callee.rs11
-rw-r--r--compiler/rustc_infer/src/infer/error_reporting/note_and_explain.rs69
-rw-r--r--compiler/rustc_macros/src/query.rs3
-rw-r--r--compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs9
-rw-r--r--compiler/rustc_metadata/src/rmeta/encoder.rs2
-rw-r--r--compiler/rustc_middle/src/mir/interpret/error.rs2
-rw-r--r--compiler/rustc_middle/src/query/erase.rs5
-rw-r--r--compiler/rustc_middle/src/query/mod.rs8
-rw-r--r--compiler/rustc_middle/src/ty/util.rs2
-rw-r--r--compiler/rustc_mir_transform/src/const_prop.rs167
-rw-r--r--compiler/rustc_mir_transform/src/const_prop_lint.rs512
-rw-r--r--compiler/rustc_mir_transform/src/coverage/mod.rs311
-rw-r--r--compiler/rustc_mir_transform/src/coverage/spans.rs119
-rw-r--r--compiler/rustc_mir_transform/src/coverage/spans/from_mir.rs6
-rw-r--r--compiler/rustc_mir_transform/src/dataflow_const_prop.rs7
-rw-r--r--compiler/rustc_mir_transform/src/errors.rs42
-rw-r--r--compiler/rustc_monomorphize/src/collector.rs8
-rw-r--r--compiler/rustc_monomorphize/src/lib.rs5
-rw-r--r--compiler/rustc_privacy/src/lib.rs90
-rw-r--r--compiler/rustc_session/src/session.rs37
-rw-r--r--compiler/rustc_span/src/symbol.rs8
-rw-r--r--compiler/rustc_target/src/spec/base/wasm.rs3
-rw-r--r--compiler/rustc_target/src/spec/mod.rs1
-rw-r--r--compiler/rustc_target/src/spec/targets/wasm32_unknown_emscripten.rs5
-rw-r--r--compiler/rustc_target/src/spec/targets/wasm32_wasi_preview1_threads.rs3
-rw-r--r--compiler/rustc_target/src/spec/targets/wasm32_wasi_preview2.rs64
-rw-r--r--compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs242
-rw-r--r--library/core/src/intrinsics.rs60
-rw-r--r--library/core/src/lib.rs1
-rw-r--r--library/core/src/num/int_macros.rs284
-rw-r--r--library/core/src/num/nonzero.rs37
-rw-r--r--library/core/src/num/uint_macros.rs249
-rw-r--r--library/core/src/ops/async_function.rs108
-rw-r--r--library/core/src/ops/mod.rs4
-rw-r--r--library/std/src/os/mod.rs3
-rw-r--r--library/std/src/os/wasi/mod.rs3
-rw-r--r--library/std/src/os/wasi_preview2/mod.rs5
-rw-r--r--library/std/src/sys/pal/mod.rs3
-rw-r--r--library/std/src/sys/pal/wasi/helpers.rs123
-rw-r--r--library/std/src/sys/pal/wasi/mod.rs132
-rw-r--r--library/std/src/sys/pal/wasi_preview2/mod.rs78
-rw-r--r--src/bootstrap/src/core/build_steps/compile.rs7
-rw-r--r--src/bootstrap/src/lib.rs2
-rw-r--r--src/doc/rustc/src/SUMMARY.md1
-rw-r--r--src/doc/rustc/src/platform-support.md1
-rw-r--r--src/doc/rustc/src/platform-support/wasm32-wasi-preview2.md30
-rw-r--r--src/doc/style-guide/src/editions.md4
-rw-r--r--src/doc/style-guide/src/expressions.md55
-rw-r--r--src/tools/clippy/tests/ui/modulo_one.rs3
-rw-r--r--src/tools/clippy/tests/ui/modulo_one.stderr8
-rw-r--r--src/tools/compiletest/src/header.rs3
-rw-r--r--src/tools/compiletest/src/header/tests.rs21
-rw-r--r--src/tools/miri/src/shims/intrinsics/mod.rs12
-rw-r--r--src/tools/miri/tests/pass/intrinsics.rs15
-rw-r--r--tests/assembly/targets/targets-elf.rs3
-rw-r--r--tests/codegen/alloc-optimisation.rs2
-rw-r--r--tests/codegen/array-map.rs3
-rw-r--r--tests/codegen/dealloc-no-unwind.rs1
-rw-r--r--tests/codegen/fewer-names.rs1
-rw-r--r--tests/codegen/integer-overflow.rs1
-rw-r--r--tests/codegen/is_val_statically_known.rs48
-rw-r--r--tests/codegen/issues/issue-116878.rs1
-rw-r--r--tests/codegen/issues/issue-44056-macos-tls-align.rs1
-rw-r--r--tests/codegen/issues/issue-69101-bounds-check.rs1
-rw-r--r--tests/codegen/match-optimizes-away.rs1
-rw-r--r--tests/codegen/pow_of_two.rs55
-rw-r--r--tests/codegen/ptr-read-metadata.rs1
-rw-r--r--tests/codegen/slice-as_chunks.rs1
-rw-r--r--tests/codegen/slice-iter-len-eq-zero.rs1
-rw-r--r--tests/codegen/slice-iter-nonnull.rs1
-rw-r--r--tests/codegen/slice-position-bounds-check.rs1
-rw-r--r--tests/codegen/vec-iter-collect-len.rs1
-rw-r--r--tests/codegen/vec-optimizes-away.rs1
-rw-r--r--tests/coverage-run-rustdoc/doctest.coverage5
-rw-r--r--tests/coverage/bad_counter_ids.cov-map16
-rw-r--r--tests/coverage/bad_counter_ids.coverage2
-rw-r--r--tests/coverage/issue-83601.cov-map16
-rw-r--r--tests/coverage/issue-83601.coverage3
-rw-r--r--tests/coverage/issue-84561.cov-map8
-rw-r--r--tests/coverage/issue-84561.coverage2
-rw-r--r--tests/coverage/partial_eq.cov-map48
-rw-r--r--tests/coverage/partial_eq.coverage3
-rw-r--r--tests/rustdoc/doc-cfg-target-feature.rs1
-rw-r--r--tests/ui/array-slice-vec/repeat_empty_ok.stderr4
-rw-r--r--tests/ui/associated-consts/issue-105330.rs1
-rw-r--r--tests/ui/associated-consts/issue-105330.stderr12
-rw-r--r--tests/ui/associated-types/impl-wf-cycle-1.stderr7
-rw-r--r--tests/ui/associated-types/impl-wf-cycle-2.stderr8
-rw-r--r--tests/ui/associated-types/impl-wf-cycle-3.rs13
-rw-r--r--tests/ui/associated-types/impl-wf-cycle-3.stderr27
-rw-r--r--tests/ui/associated-types/impl-wf-cycle-4.rs15
-rw-r--r--tests/ui/associated-types/impl-wf-cycle-4.stderr25
-rw-r--r--tests/ui/associated-types/impl-wf-cycle-5.fixed31
-rw-r--r--tests/ui/associated-types/impl-wf-cycle-5.rs32
-rw-r--r--tests/ui/associated-types/impl-wf-cycle-5.stderr31
-rw-r--r--tests/ui/associated-types/impl-wf-cycle-6.fixed30
-rw-r--r--tests/ui/associated-types/impl-wf-cycle-6.rs31
-rw-r--r--tests/ui/associated-types/impl-wf-cycle-6.stderr29
-rw-r--r--tests/ui/associated-types/issue-38821.rs15
-rw-r--r--tests/ui/associated-types/issue-38821.stderr268
-rw-r--r--tests/ui/async-await/async-fn/simple.rs16
-rw-r--r--tests/ui/check-cfg/well-known-values.stderr4
-rw-r--r--tests/ui/coercion/issue-53475.rs2
-rw-r--r--tests/ui/const-generics/bad-generic-in-copy-impl.rs1
-rw-r--r--tests/ui/const-generics/bad-generic-in-copy-impl.stderr10
-rw-r--r--tests/ui/const-generics/issues/issue-61336-2.stderr2
-rw-r--r--tests/ui/const-generics/issues/issue-61336.stderr2
-rw-r--r--tests/ui/consts/const-blocks/migrate-fail.stderr4
-rw-r--r--tests/ui/consts/const-blocks/nll-fail.stderr4
-rw-r--r--tests/ui/consts/const-err-late.stderr8
-rw-r--r--tests/ui/consts/is_val_statically_known.rs15
-rw-r--r--tests/ui/consts/issue-65348.rs7
-rw-r--r--tests/ui/did_you_mean/bad-assoc-ty.stderr9
-rw-r--r--tests/ui/dst/dst-bad-assign-3.stderr1
-rw-r--r--tests/ui/dst/dst-bad-assign.stderr1
-rw-r--r--tests/ui/dyn-star/no-implicit-dyn-star.stderr1
-rw-r--r--tests/ui/enum-discriminant/issue-72554.rs1
-rw-r--r--tests/ui/enum-discriminant/issue-72554.stderr21
-rw-r--r--tests/ui/for-loop-while/issue-69841.rs1
-rw-r--r--tests/ui/generic-associated-types/issue-79422.extended.stderr1
-rw-r--r--tests/ui/impl-trait/dyn-impl-type-mismatch.rs18
-rw-r--r--tests/ui/impl-trait/dyn-impl-type-mismatch.stderr43
-rw-r--r--tests/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr2
-rw-r--r--tests/ui/issue-76387-llvm-miscompile.rs1
-rw-r--r--tests/ui/methods/issues/issue-61525.stderr1
-rw-r--r--tests/ui/privacy/private-type-in-interface.rs3
-rw-r--r--tests/ui/privacy/private-type-in-interface.stderr16
-rw-r--r--tests/ui/repeat-expr/repeat-to-run-dtor-twice.stderr2
-rw-r--r--tests/ui/rfcs/rfc-2632-const-trait-impl/specializing-constness-2.stderr14
-rw-r--r--tests/ui/specialization/min_specialization/bad-const-wf-doesnt-specialize.rs1
-rw-r--r--tests/ui/specialization/min_specialization/bad-const-wf-doesnt-specialize.stderr22
-rw-r--r--tests/ui/trait-bounds/issue-119530-sugg-from-fn.stderr2
-rw-r--r--tests/ui/typeck/typeck_type_placeholder_item.rs1
-rw-r--r--tests/ui/typeck/typeck_type_placeholder_item.stderr37
-rw-r--r--triagebot.toml136
152 files changed, 3113 insertions, 1468 deletions
diff --git a/compiler/rustc_codegen_cranelift/src/intrinsics/mod.rs b/compiler/rustc_codegen_cranelift/src/intrinsics/mod.rs
index a27853fa0a8..819cb5ef137 100644
--- a/compiler/rustc_codegen_cranelift/src/intrinsics/mod.rs
+++ b/compiler/rustc_codegen_cranelift/src/intrinsics/mod.rs
@@ -443,6 +443,12 @@ fn codegen_regular_intrinsic_call<'tcx>(
 
             ret.write_cvalue(fx, a);
         }
+        sym::is_val_statically_known => {
+            intrinsic_args!(fx, args => (_a); intrinsic);
+
+            let res = fx.bcx.ins().iconst(types::I8, 0);
+            ret.write_cvalue(fx, CValue::by_val(res, ret.layout()));
+        }
         sym::breakpoint => {
             intrinsic_args!(fx, args => (); intrinsic);
 
diff --git a/compiler/rustc_codegen_gcc/src/context.rs b/compiler/rustc_codegen_gcc/src/context.rs
index 053f759329f..5760d96165d 100644
--- a/compiler/rustc_codegen_gcc/src/context.rs
+++ b/compiler/rustc_codegen_gcc/src/context.rs
@@ -196,15 +196,16 @@ impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
 
         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_unreachable", "abort", "__builtin_expect", /*"__builtin_expect_with_probability",*/
+            "__builtin_constant_p", "__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() {
diff --git a/compiler/rustc_codegen_gcc/src/intrinsic/mod.rs b/compiler/rustc_codegen_gcc/src/intrinsic/mod.rs
index 85b891fce3e..eac8cb43779 100644
--- a/compiler/rustc_codegen_gcc/src/intrinsic/mod.rs
+++ b/compiler/rustc_codegen_gcc/src/intrinsic/mod.rs
@@ -123,6 +123,12 @@ impl<'a, 'gcc, 'tcx> IntrinsicCallMethods<'tcx> for Builder<'a, 'gcc, 'tcx> {
                 sym::unlikely => {
                     self.expect(args[0].immediate(), false)
                 }
+                sym::is_val_statically_known => {
+                    let a = args[0].immediate();
+                    let builtin = self.context.get_builtin_function("__builtin_constant_p");
+                    let res = self.context.new_call(None, builtin, &[a]);
+                    self.icmp(IntPredicate::IntEQ, res, self.const_i32(0))
+                }
                 kw::Try => {
                     try_intrinsic(
                         self,
diff --git a/compiler/rustc_codegen_llvm/src/context.rs b/compiler/rustc_codegen_llvm/src/context.rs
index f3b2caf9b80..5ef05dfbe4c 100644
--- a/compiler/rustc_codegen_llvm/src/context.rs
+++ b/compiler/rustc_codegen_llvm/src/context.rs
@@ -916,6 +916,20 @@ impl<'ll> CodegenCx<'ll, '_> {
         ifn!("llvm.lifetime.start.p0i8", fn(t_i64, ptr) -> void);
         ifn!("llvm.lifetime.end.p0i8", fn(t_i64, ptr) -> void);
 
+        // FIXME: This is an infinitesimally small portion of the types you can
+        // pass to this intrinsic, if we can ever lazily register intrinsics we
+        // should register these when they're used, that way any type can be
+        // passed.
+        ifn!("llvm.is.constant.i1", fn(i1) -> i1);
+        ifn!("llvm.is.constant.i8", fn(t_i8) -> i1);
+        ifn!("llvm.is.constant.i16", fn(t_i16) -> i1);
+        ifn!("llvm.is.constant.i32", fn(t_i32) -> i1);
+        ifn!("llvm.is.constant.i64", fn(t_i64) -> i1);
+        ifn!("llvm.is.constant.i128", fn(t_i128) -> i1);
+        ifn!("llvm.is.constant.isize", fn(t_isize) -> i1);
+        ifn!("llvm.is.constant.f32", fn(t_f32) -> i1);
+        ifn!("llvm.is.constant.f64", fn(t_f64) -> i1);
+
         ifn!("llvm.expect.i1", fn(i1, i1) -> i1);
         ifn!("llvm.eh.typeid.for", fn(ptr) -> t_i32);
         ifn!("llvm.localescape", fn(...) -> void);
diff --git a/compiler/rustc_codegen_llvm/src/intrinsic.rs b/compiler/rustc_codegen_llvm/src/intrinsic.rs
index a0f9d5cf7cd..f1a6f7bd8e6 100644
--- a/compiler/rustc_codegen_llvm/src/intrinsic.rs
+++ b/compiler/rustc_codegen_llvm/src/intrinsic.rs
@@ -119,6 +119,10 @@ impl<'ll, 'tcx> IntrinsicCallMethods<'tcx> for Builder<'_, 'll, 'tcx> {
             sym::likely => {
                 self.call_intrinsic("llvm.expect.i1", &[args[0].immediate(), self.const_bool(true)])
             }
+            sym::is_val_statically_known => self.call_intrinsic(
+                &format!("llvm.is.constant.{:?}", args[0].layout.immediate_llvm_type(self.cx)),
+                &[args[0].immediate()],
+            ),
             sym::unlikely => self
                 .call_intrinsic("llvm.expect.i1", &[args[0].immediate(), self.const_bool(false)]),
             kw::Try => {
diff --git a/compiler/rustc_const_eval/src/const_eval/machine.rs b/compiler/rustc_const_eval/src/const_eval/machine.rs
index d5a33b6f01e..274ff25fb9b 100644
--- a/compiler/rustc_const_eval/src/const_eval/machine.rs
+++ b/compiler/rustc_const_eval/src/const_eval/machine.rs
@@ -531,6 +531,11 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
                     )?;
                 }
             }
+            // The intrinsic represents whether the value is known to the optimizer (LLVM).
+            // We're not doing any optimizations here, so there is no optimizer that could know the value.
+            // (We know the value here in the machine of course, but this is the runtime of that code,
+            // not the optimization stage.)
+            sym::is_val_statically_known => ecx.write_scalar(Scalar::from_bool(false), dest)?,
             _ => {
                 throw_unsup_format!(
                     "intrinsic `{intrinsic_name}` is not supported at compile-time"
diff --git a/compiler/rustc_const_eval/src/errors.rs b/compiler/rustc_const_eval/src/errors.rs
index 4a654480ef5..064d97a49d7 100644
--- a/compiler/rustc_const_eval/src/errors.rs
+++ b/compiler/rustc_const_eval/src/errors.rs
@@ -864,9 +864,6 @@ impl<'tcx> ReportErrorExt for InvalidProgramInfo<'tcx> {
             InvalidProgramInfo::FnAbiAdjustForForeignAbi(_) => {
                 rustc_middle::error::middle_adjust_for_foreign_abi_error
             }
-            InvalidProgramInfo::ConstPropNonsense => {
-                panic!("We had const-prop nonsense, this should never be printed")
-            }
         }
     }
     fn add_args<G: EmissionGuarantee>(
@@ -875,9 +872,7 @@ impl<'tcx> ReportErrorExt for InvalidProgramInfo<'tcx> {
         builder: &mut DiagnosticBuilder<'_, G>,
     ) {
         match self {
-            InvalidProgramInfo::TooGeneric
-            | InvalidProgramInfo::AlreadyReported(_)
-            | InvalidProgramInfo::ConstPropNonsense => {}
+            InvalidProgramInfo::TooGeneric | InvalidProgramInfo::AlreadyReported(_) => {}
             InvalidProgramInfo::Layout(e) => {
                 // The level doesn't matter, `diag` is consumed without it being used.
                 let dummy_level = Level::Bug;
diff --git a/compiler/rustc_const_eval/src/interpret/operand.rs b/compiler/rustc_const_eval/src/interpret/operand.rs
index b39b219b46a..80d4bda4827 100644
--- a/compiler/rustc_const_eval/src/interpret/operand.rs
+++ b/compiler/rustc_const_eval/src/interpret/operand.rs
@@ -643,11 +643,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         let layout = self.layout_of_local(frame, local, layout)?;
         let op = *frame.locals[local].access()?;
         if matches!(op, Operand::Immediate(_)) {
-            if layout.is_unsized() {
-                // ConstProp marks *all* locals as `Immediate::Uninit` since it cannot
-                // efficiently check whether they are sized. We have to catch that case here.
-                throw_inval!(ConstPropNonsense);
-            }
+            assert!(!layout.is_unsized());
         }
         Ok(OpTy { op, layout })
     }
diff --git a/compiler/rustc_const_eval/src/interpret/place.rs b/compiler/rustc_const_eval/src/interpret/place.rs
index b39efad61bb..772445f4f62 100644
--- a/compiler/rustc_const_eval/src/interpret/place.rs
+++ b/compiler/rustc_const_eval/src/interpret/place.rs
@@ -519,11 +519,7 @@ where
         } else {
             // Unsized `Local` isn't okay (we cannot store the metadata).
             match frame_ref.locals[local].access()? {
-                Operand::Immediate(_) => {
-                    // ConstProp marks *all* locals as `Immediate::Uninit` since it cannot
-                    // efficiently check whether they are sized. We have to catch that case here.
-                    throw_inval!(ConstPropNonsense);
-                }
+                Operand::Immediate(_) => bug!(),
                 Operand::Indirect(mplace) => Place::Ptr(*mplace),
             }
         };
@@ -816,17 +812,8 @@ where
         // avoid force_allocation.
         let src = match self.read_immediate_raw(src)? {
             Right(src_val) => {
-                // FIXME(const_prop): Const-prop can possibly evaluate an
-                // unsized copy operation when it thinks that the type is
-                // actually sized, due to a trivially false where-clause
-                // predicate like `where Self: Sized` with `Self = dyn Trait`.
-                // See #102553 for an example of such a predicate.
-                if src.layout().is_unsized() {
-                    throw_inval!(ConstPropNonsense);
-                }
-                if dest.layout().is_unsized() {
-                    throw_inval!(ConstPropNonsense);
-                }
+                assert!(!src.layout().is_unsized());
+                assert!(!dest.layout().is_unsized());
                 assert_eq!(src.layout().size, dest.layout().size);
                 // Yay, we got a value that we can write directly.
                 return if layout_compat {
diff --git a/compiler/rustc_const_eval/src/interpret/projection.rs b/compiler/rustc_const_eval/src/interpret/projection.rs
index 9a034ba22b9..bd60e066f72 100644
--- a/compiler/rustc_const_eval/src/interpret/projection.rs
+++ b/compiler/rustc_const_eval/src/interpret/projection.rs
@@ -153,11 +153,7 @@ where
 
         // Offset may need adjustment for unsized fields.
         let (meta, offset) = if field_layout.is_unsized() {
-            if base.layout().is_sized() {
-                // An unsized field of a sized type? Sure...
-                // But const-prop actually feeds us such nonsense MIR! (see test `const_prop/issue-86351.rs`)
-                throw_inval!(ConstPropNonsense);
-            }
+            assert!(!base.layout().is_sized());
             let base_meta = base.meta();
             // Re-use parent metadata to determine dynamic field layout.
             // With custom DSTS, this *will* execute user-defined code, but the same
@@ -205,29 +201,26 @@ where
         // see https://github.com/rust-lang/rust/issues/93688#issuecomment-1032929496.)
         // So we just "offset" by 0.
         let layout = base.layout().for_variant(self, variant);
-        if layout.abi.is_uninhabited() {
-            // `read_discriminant` should have excluded uninhabited variants... but ConstProp calls
-            // us on dead code.
-            // In the future we might want to allow this to permit code like this:
-            // (this is a Rust/MIR pseudocode mix)
-            // ```
-            // enum Option2 {
-            //   Some(i32, !),
-            //   None,
-            // }
-            //
-            // fn panic() -> ! { panic!() }
-            //
-            // let x: Option2;
-            // x.Some.0 = 42;
-            // x.Some.1 = panic();
-            // SetDiscriminant(x, Some);
-            // ```
-            // However, for now we don't generate such MIR, and this check here *has* found real
-            // bugs (see https://github.com/rust-lang/rust/issues/115145), so we will keep rejecting
-            // it.
-            throw_inval!(ConstPropNonsense)
-        }
+        // In the future we might want to allow this to permit code like this:
+        // (this is a Rust/MIR pseudocode mix)
+        // ```
+        // enum Option2 {
+        //   Some(i32, !),
+        //   None,
+        // }
+        //
+        // fn panic() -> ! { panic!() }
+        //
+        // let x: Option2;
+        // x.Some.0 = 42;
+        // x.Some.1 = panic();
+        // SetDiscriminant(x, Some);
+        // ```
+        // However, for now we don't generate such MIR, and this check here *has* found real
+        // bugs (see https://github.com/rust-lang/rust/issues/115145), so we will keep rejecting
+        // it.
+        assert!(!layout.abi.is_uninhabited());
+
         // This cannot be `transmute` as variants *can* have a smaller size than the entire enum.
         base.offset(Size::ZERO, layout, self)
     }
diff --git a/compiler/rustc_const_eval/src/util/mod.rs b/compiler/rustc_const_eval/src/util/mod.rs
index 1e58bd645cd..a8060463b69 100644
--- a/compiler/rustc_const_eval/src/util/mod.rs
+++ b/compiler/rustc_const_eval/src/util/mod.rs
@@ -14,7 +14,7 @@ pub use self::type_name::type_name;
 /// Classify whether an operator is "left-homogeneous", i.e., the LHS has the
 /// same type as the result.
 #[inline]
-pub(crate) fn binop_left_homogeneous(op: mir::BinOp) -> bool {
+pub fn binop_left_homogeneous(op: mir::BinOp) -> bool {
     use rustc_middle::mir::BinOp::*;
     match op {
         Add | AddUnchecked | Sub | SubUnchecked | Mul | MulUnchecked | Div | Rem | BitXor
@@ -26,7 +26,7 @@ pub(crate) fn binop_left_homogeneous(op: mir::BinOp) -> bool {
 /// Classify whether an operator is "right-homogeneous", i.e., the RHS has the
 /// same type as the LHS.
 #[inline]
-pub(crate) fn binop_right_homogeneous(op: mir::BinOp) -> bool {
+pub fn binop_right_homogeneous(op: mir::BinOp) -> bool {
     use rustc_middle::mir::BinOp::*;
     match op {
         Add | AddUnchecked | Sub | SubUnchecked | Mul | MulUnchecked | Div | Rem | BitXor
diff --git a/compiler/rustc_hir/src/lang_items.rs b/compiler/rustc_hir/src/lang_items.rs
index 85d10872b3d..9fb318e2ae7 100644
--- a/compiler/rustc_hir/src/lang_items.rs
+++ b/compiler/rustc_hir/src/lang_items.rs
@@ -208,6 +208,10 @@ language_item_table! {
     FnMut,                   sym::fn_mut,              fn_mut_trait,               Target::Trait,          GenericRequirement::Exact(1);
     FnOnce,                  sym::fn_once,             fn_once_trait,              Target::Trait,          GenericRequirement::Exact(1);
 
+    AsyncFn,                 sym::async_fn,            async_fn_trait,             Target::Trait,          GenericRequirement::Exact(1);
+    AsyncFnMut,              sym::async_fn_mut,        async_fn_mut_trait,         Target::Trait,          GenericRequirement::Exact(1);
+    AsyncFnOnce,             sym::async_fn_once,       async_fn_once_trait,        Target::Trait,          GenericRequirement::Exact(1);
+
     FnOnceOutput,            sym::fn_once_output,      fn_once_output,             Target::AssocTy,        GenericRequirement::None;
 
     Iterator,                sym::iterator,            iterator_trait,             Target::Trait,          GenericRequirement::Exact(0);
diff --git a/compiler/rustc_hir_analysis/src/check/intrinsic.rs b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
index 7c3e296dfce..60e4403c1c7 100644
--- a/compiler/rustc_hir_analysis/src/check/intrinsic.rs
+++ b/compiler/rustc_hir_analysis/src/check/intrinsic.rs
@@ -453,6 +453,8 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
 
             sym::black_box => (1, vec![param(0)], param(0)),
 
+            sym::is_val_statically_known => (1, vec![param(0)], tcx.types.bool),
+
             sym::const_eval_select => (4, vec![param(0), param(1), param(2)], param(3)),
 
             sym::vtable_size | sym::vtable_align => {
diff --git a/compiler/rustc_hir_analysis/src/coherence/builtin.rs b/compiler/rustc_hir_analysis/src/coherence/builtin.rs
index 8d362f74b0a..5a387844593 100644
--- a/compiler/rustc_hir_analysis/src/coherence/builtin.rs
+++ b/compiler/rustc_hir_analysis/src/coherence/builtin.rs
@@ -25,14 +25,21 @@ use rustc_trait_selection::traits::ObligationCtxt;
 use rustc_trait_selection::traits::{self, ObligationCause};
 use std::collections::BTreeMap;
 
-pub fn check_trait(tcx: TyCtxt<'_>, trait_def_id: DefId) {
+pub fn check_trait(tcx: TyCtxt<'_>, trait_def_id: DefId) -> Result<(), ErrorGuaranteed> {
     let lang_items = tcx.lang_items();
-    Checker { tcx, trait_def_id }
-        .check(lang_items.drop_trait(), visit_implementation_of_drop)
-        .check(lang_items.copy_trait(), visit_implementation_of_copy)
-        .check(lang_items.const_param_ty_trait(), visit_implementation_of_const_param_ty)
-        .check(lang_items.coerce_unsized_trait(), visit_implementation_of_coerce_unsized)
-        .check(lang_items.dispatch_from_dyn_trait(), visit_implementation_of_dispatch_from_dyn);
+    let checker = Checker { tcx, trait_def_id };
+    let mut res = checker.check(lang_items.drop_trait(), visit_implementation_of_drop);
+    res = res.and(checker.check(lang_items.copy_trait(), visit_implementation_of_copy));
+    res = res.and(
+        checker.check(lang_items.const_param_ty_trait(), visit_implementation_of_const_param_ty),
+    );
+    res = res.and(
+        checker.check(lang_items.coerce_unsized_trait(), visit_implementation_of_coerce_unsized),
+    );
+    res.and(
+        checker
+            .check(lang_items.dispatch_from_dyn_trait(), visit_implementation_of_dispatch_from_dyn),
+    )
 }
 
 struct Checker<'tcx> {
@@ -41,33 +48,40 @@ struct Checker<'tcx> {
 }
 
 impl<'tcx> Checker<'tcx> {
-    fn check<F>(&self, trait_def_id: Option<DefId>, mut f: F) -> &Self
+    fn check<F>(&self, trait_def_id: Option<DefId>, mut f: F) -> Result<(), ErrorGuaranteed>
     where
-        F: FnMut(TyCtxt<'tcx>, LocalDefId),
+        F: FnMut(TyCtxt<'tcx>, LocalDefId) -> Result<(), ErrorGuaranteed>,
     {
+        let mut res = Ok(());
         if Some(self.trait_def_id) == trait_def_id {
             for &impl_def_id in self.tcx.hir().trait_impls(self.trait_def_id) {
-                f(self.tcx, impl_def_id);
+                res = res.and(f(self.tcx, impl_def_id));
             }
         }
-        self
+        res
     }
 }
 
-fn visit_implementation_of_drop(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
+fn visit_implementation_of_drop(
+    tcx: TyCtxt<'_>,
+    impl_did: LocalDefId,
+) -> Result<(), ErrorGuaranteed> {
     // Destructors only work on local ADT types.
     match tcx.type_of(impl_did).instantiate_identity().kind() {
-        ty::Adt(def, _) if def.did().is_local() => return,
-        ty::Error(_) => return,
+        ty::Adt(def, _) if def.did().is_local() => return Ok(()),
+        ty::Error(_) => return Ok(()),
         _ => {}
     }
 
     let impl_ = tcx.hir().expect_item(impl_did).expect_impl();
 
-    tcx.dcx().emit_err(errors::DropImplOnWrongItem { span: impl_.self_ty.span });
+    Err(tcx.dcx().emit_err(errors::DropImplOnWrongItem { span: impl_.self_ty.span }))
 }
 
-fn visit_implementation_of_copy(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
+fn visit_implementation_of_copy(
+    tcx: TyCtxt<'_>,
+    impl_did: LocalDefId,
+) -> Result<(), ErrorGuaranteed> {
     debug!("visit_implementation_of_copy: impl_did={:?}", impl_did);
 
     let self_type = tcx.type_of(impl_did).instantiate_identity();
@@ -79,59 +93,68 @@ fn visit_implementation_of_copy(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
     debug!("visit_implementation_of_copy: self_type={:?} (free)", self_type);
 
     let span = match tcx.hir().expect_item(impl_did).expect_impl() {
-        hir::Impl { polarity: hir::ImplPolarity::Negative(_), .. } => return,
+        hir::Impl { polarity: hir::ImplPolarity::Negative(_), .. } => return Ok(()),
         hir::Impl { self_ty, .. } => self_ty.span,
     };
 
     let cause = traits::ObligationCause::misc(span, impl_did);
     match type_allowed_to_implement_copy(tcx, param_env, self_type, cause) {
-        Ok(()) => {}
+        Ok(()) => Ok(()),
         Err(CopyImplementationError::InfringingFields(fields)) => {
-            infringing_fields_error(tcx, fields, LangItem::Copy, impl_did, span);
+            Err(infringing_fields_error(tcx, fields, LangItem::Copy, impl_did, span))
         }
         Err(CopyImplementationError::NotAnAdt) => {
-            tcx.dcx().emit_err(errors::CopyImplOnNonAdt { span });
+            Err(tcx.dcx().emit_err(errors::CopyImplOnNonAdt { span }))
         }
         Err(CopyImplementationError::HasDestructor) => {
-            tcx.dcx().emit_err(errors::CopyImplOnTypeWithDtor { span });
+            Err(tcx.dcx().emit_err(errors::CopyImplOnTypeWithDtor { span }))
         }
     }
 }
 
-fn visit_implementation_of_const_param_ty(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
+fn visit_implementation_of_const_param_ty(
+    tcx: TyCtxt<'_>,
+    impl_did: LocalDefId,
+) -> Result<(), ErrorGuaranteed> {
     let self_type = tcx.type_of(impl_did).instantiate_identity();
     assert!(!self_type.has_escaping_bound_vars());
 
     let param_env = tcx.param_env(impl_did);
 
     let span = match tcx.hir().expect_item(impl_did).expect_impl() {
-        hir::Impl { polarity: hir::ImplPolarity::Negative(_), .. } => return,
+        hir::Impl { polarity: hir::ImplPolarity::Negative(_), .. } => return Ok(()),
         impl_ => impl_.self_ty.span,
     };
 
     let cause = traits::ObligationCause::misc(span, impl_did);
     match type_allowed_to_implement_const_param_ty(tcx, param_env, self_type, cause) {
-        Ok(()) => {}
+        Ok(()) => Ok(()),
         Err(ConstParamTyImplementationError::InfrigingFields(fields)) => {
-            infringing_fields_error(tcx, fields, LangItem::ConstParamTy, impl_did, span);
+            Err(infringing_fields_error(tcx, fields, LangItem::ConstParamTy, impl_did, span))
         }
         Err(ConstParamTyImplementationError::NotAnAdtOrBuiltinAllowed) => {
-            tcx.dcx().emit_err(errors::ConstParamTyImplOnNonAdt { span });
+            Err(tcx.dcx().emit_err(errors::ConstParamTyImplOnNonAdt { span }))
         }
     }
 }
 
-fn visit_implementation_of_coerce_unsized(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
+fn visit_implementation_of_coerce_unsized(
+    tcx: TyCtxt<'_>,
+    impl_did: LocalDefId,
+) -> Result<(), ErrorGuaranteed> {
     debug!("visit_implementation_of_coerce_unsized: impl_did={:?}", impl_did);
 
     // Just compute this for the side-effects, in particular reporting
     // errors; other parts of the code may demand it for the info of
     // course.
     let span = tcx.def_span(impl_did);
-    tcx.at(span).coerce_unsized_info(impl_did);
+    tcx.at(span).ensure().coerce_unsized_info(impl_did)
 }
 
-fn visit_implementation_of_dispatch_from_dyn(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
+fn visit_implementation_of_dispatch_from_dyn(
+    tcx: TyCtxt<'_>,
+    impl_did: LocalDefId,
+) -> Result<(), ErrorGuaranteed> {
     debug!("visit_implementation_of_dispatch_from_dyn: impl_did={:?}", impl_did);
 
     let span = tcx.def_span(impl_did);
@@ -166,26 +189,28 @@ fn visit_implementation_of_dispatch_from_dyn(tcx: TyCtxt<'_>, impl_did: LocalDef
     match (source.kind(), target.kind()) {
         (&Ref(r_a, _, mutbl_a), Ref(r_b, _, mutbl_b))
             if infcx.at(&cause, param_env).eq(DefineOpaqueTypes::No, r_a, *r_b).is_ok()
-                && mutbl_a == *mutbl_b => {}
-        (&RawPtr(tm_a), &RawPtr(tm_b)) if tm_a.mutbl == tm_b.mutbl => (),
+                && mutbl_a == *mutbl_b =>
+        {
+            Ok(())
+        }
+        (&RawPtr(tm_a), &RawPtr(tm_b)) if tm_a.mutbl == tm_b.mutbl => Ok(()),
         (&Adt(def_a, args_a), &Adt(def_b, args_b)) if def_a.is_struct() && def_b.is_struct() => {
             if def_a != def_b {
                 let source_path = tcx.def_path_str(def_a.did());
                 let target_path = tcx.def_path_str(def_b.did());
 
-                tcx.dcx().emit_err(errors::DispatchFromDynCoercion {
+                return Err(tcx.dcx().emit_err(errors::DispatchFromDynCoercion {
                     span,
                     trait_name: "DispatchFromDyn",
                     note: true,
                     source_path,
                     target_path,
-                });
-
-                return;
+                }));
             }
 
+            let mut res = Ok(());
             if def_a.repr().c() || def_a.repr().packed() {
-                tcx.dcx().emit_err(errors::DispatchFromDynRepr { span });
+                res = Err(tcx.dcx().emit_err(errors::DispatchFromDynRepr { span }));
             }
 
             let fields = &def_a.non_enum_variant().fields;
@@ -207,11 +232,11 @@ fn visit_implementation_of_dispatch_from_dyn(tcx: TyCtxt<'_>, impl_did: LocalDef
                         infcx.at(&cause, param_env).eq(DefineOpaqueTypes::No, ty_a, ty_b)
                     {
                         if ok.obligations.is_empty() {
-                            tcx.dcx().emit_err(errors::DispatchFromDynZST {
+                            res = Err(tcx.dcx().emit_err(errors::DispatchFromDynZST {
                                 span,
                                 name: field.name,
                                 ty: ty_a,
-                            });
+                            }));
 
                             return false;
                         }
@@ -222,13 +247,13 @@ fn visit_implementation_of_dispatch_from_dyn(tcx: TyCtxt<'_>, impl_did: LocalDef
                 .collect::<Vec<_>>();
 
             if coerced_fields.is_empty() {
-                tcx.dcx().emit_err(errors::DispatchFromDynSingle {
+                res = Err(tcx.dcx().emit_err(errors::DispatchFromDynSingle {
                     span,
                     trait_name: "DispatchFromDyn",
                     note: true,
-                });
+                }));
             } else if coerced_fields.len() > 1 {
-                tcx.dcx().emit_err(errors::DispatchFromDynMulti {
+                res = Err(tcx.dcx().emit_err(errors::DispatchFromDynMulti {
                     span,
                     coercions_note: true,
                     number: coerced_fields.len(),
@@ -244,7 +269,7 @@ fn visit_implementation_of_dispatch_from_dyn(tcx: TyCtxt<'_>, impl_did: LocalDef
                         })
                         .collect::<Vec<_>>()
                         .join(", "),
-                });
+                }));
             } else {
                 let ocx = ObligationCtxt::new(&infcx);
                 for field in coerced_fields {
@@ -261,21 +286,25 @@ fn visit_implementation_of_dispatch_from_dyn(tcx: TyCtxt<'_>, impl_did: LocalDef
                 }
                 let errors = ocx.select_all_or_error();
                 if !errors.is_empty() {
-                    infcx.err_ctxt().report_fulfillment_errors(errors);
+                    res = Err(infcx.err_ctxt().report_fulfillment_errors(errors));
                 }
 
                 // Finally, resolve all regions.
                 let outlives_env = OutlivesEnvironment::new(param_env);
-                let _ = ocx.resolve_regions_and_report_errors(impl_did, &outlives_env);
+                res = res.and(ocx.resolve_regions_and_report_errors(impl_did, &outlives_env));
             }
+            res
         }
-        _ => {
-            tcx.dcx().emit_err(errors::CoerceUnsizedMay { span, trait_name: "DispatchFromDyn" });
-        }
+        _ => Err(tcx
+            .dcx()
+            .emit_err(errors::CoerceUnsizedMay { span, trait_name: "DispatchFromDyn" })),
     }
 }
 
-pub fn coerce_unsized_info<'tcx>(tcx: TyCtxt<'tcx>, impl_did: LocalDefId) -> CoerceUnsizedInfo {
+pub fn coerce_unsized_info<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    impl_did: LocalDefId,
+) -> Result<CoerceUnsizedInfo, ErrorGuaranteed> {
     debug!("compute_coerce_unsized_info(impl_did={:?})", impl_did);
     let span = tcx.def_span(impl_did);
 
@@ -292,8 +321,6 @@ pub fn coerce_unsized_info<'tcx>(tcx: TyCtxt<'tcx>, impl_did: LocalDefId) -> Coe
     let param_env = tcx.param_env(impl_did);
     assert!(!source.has_escaping_bound_vars());
 
-    let err_info = CoerceUnsizedInfo { custom_kind: None };
-
     debug!("visit_implementation_of_coerce_unsized: {:?} -> {:?} (free)", source, target);
 
     let infcx = tcx.infer_ctxt().build();
@@ -337,14 +364,13 @@ pub fn coerce_unsized_info<'tcx>(tcx: TyCtxt<'tcx>, impl_did: LocalDefId) -> Coe
             if def_a != def_b {
                 let source_path = tcx.def_path_str(def_a.did());
                 let target_path = tcx.def_path_str(def_b.did());
-                tcx.dcx().emit_err(errors::DispatchFromDynSame {
+                return Err(tcx.dcx().emit_err(errors::DispatchFromDynSame {
                     span,
                     trait_name: "CoerceUnsized",
                     note: true,
                     source_path,
                     target_path,
-                });
-                return err_info;
+                }));
             }
 
             // Here we are considering a case of converting
@@ -419,12 +445,11 @@ pub fn coerce_unsized_info<'tcx>(tcx: TyCtxt<'tcx>, impl_did: LocalDefId) -> Coe
                 .collect::<Vec<_>>();
 
             if diff_fields.is_empty() {
-                tcx.dcx().emit_err(errors::CoerceUnsizedOneField {
+                return Err(tcx.dcx().emit_err(errors::CoerceUnsizedOneField {
                     span,
                     trait_name: "CoerceUnsized",
                     note: true,
-                });
-                return err_info;
+                }));
             } else if diff_fields.len() > 1 {
                 let item = tcx.hir().expect_item(impl_did);
                 let span = if let ItemKind::Impl(hir::Impl { of_trait: Some(t), .. }) = &item.kind {
@@ -433,7 +458,7 @@ pub fn coerce_unsized_info<'tcx>(tcx: TyCtxt<'tcx>, impl_did: LocalDefId) -> Coe
                     tcx.def_span(impl_did)
                 };
 
-                tcx.dcx().emit_err(errors::CoerceUnsizedMulti {
+                return Err(tcx.dcx().emit_err(errors::CoerceUnsizedMulti {
                     span,
                     coercions_note: true,
                     number: diff_fields.len(),
@@ -442,9 +467,7 @@ pub fn coerce_unsized_info<'tcx>(tcx: TyCtxt<'tcx>, impl_did: LocalDefId) -> Coe
                         .map(|&(i, a, b)| format!("`{}` (`{}` to `{}`)", fields[i].name, a, b))
                         .collect::<Vec<_>>()
                         .join(", "),
-                });
-
-                return err_info;
+                }));
             }
 
             let (i, a, b) = diff_fields[0];
@@ -453,8 +476,9 @@ pub fn coerce_unsized_info<'tcx>(tcx: TyCtxt<'tcx>, impl_did: LocalDefId) -> Coe
         }
 
         _ => {
-            tcx.dcx().emit_err(errors::DispatchFromDynStruct { span, trait_name: "CoerceUnsized" });
-            return err_info;
+            return Err(tcx
+                .dcx()
+                .emit_err(errors::DispatchFromDynStruct { span, trait_name: "CoerceUnsized" }));
         }
     };
 
@@ -477,7 +501,7 @@ pub fn coerce_unsized_info<'tcx>(tcx: TyCtxt<'tcx>, impl_did: LocalDefId) -> Coe
     let outlives_env = OutlivesEnvironment::new(param_env);
     let _ = ocx.resolve_regions_and_report_errors(impl_did, &outlives_env);
 
-    CoerceUnsizedInfo { custom_kind: kind }
+    Ok(CoerceUnsizedInfo { custom_kind: kind })
 }
 
 fn infringing_fields_error(
diff --git a/compiler/rustc_hir_analysis/src/coherence/mod.rs b/compiler/rustc_hir_analysis/src/coherence/mod.rs
index 561a254e89e..dafa899ef24 100644
--- a/compiler/rustc_hir_analysis/src/coherence/mod.rs
+++ b/compiler/rustc_hir_analysis/src/coherence/mod.rs
@@ -10,6 +10,7 @@ use rustc_errors::{error_code, struct_span_code_err};
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_middle::query::Providers;
 use rustc_middle::ty::{self, TyCtxt, TypeVisitableExt};
+use rustc_span::ErrorGuaranteed;
 use rustc_trait_selection::traits;
 
 mod builtin;
@@ -18,7 +19,11 @@ mod inherent_impls_overlap;
 mod orphan;
 mod unsafety;
 
-fn check_impl(tcx: TyCtxt<'_>, impl_def_id: LocalDefId, trait_ref: ty::TraitRef<'_>) {
+fn check_impl(
+    tcx: TyCtxt<'_>,
+    impl_def_id: LocalDefId,
+    trait_ref: ty::TraitRef<'_>,
+) -> Result<(), ErrorGuaranteed> {
     debug!(
         "(checking implementation) adding impl for trait '{:?}', item '{}'",
         trait_ref,
@@ -28,18 +33,18 @@ fn check_impl(tcx: TyCtxt<'_>, impl_def_id: LocalDefId, trait_ref: ty::TraitRef<
     // Skip impls where one of the self type is an error type.
     // This occurs with e.g., resolve failures (#30589).
     if trait_ref.references_error() {
-        return;
+        return Ok(());
     }
 
-    enforce_trait_manually_implementable(tcx, impl_def_id, trait_ref.def_id);
-    enforce_empty_impls_for_marker_traits(tcx, impl_def_id, trait_ref.def_id);
+    enforce_trait_manually_implementable(tcx, impl_def_id, trait_ref.def_id)
+        .and(enforce_empty_impls_for_marker_traits(tcx, impl_def_id, trait_ref.def_id))
 }
 
 fn enforce_trait_manually_implementable(
     tcx: TyCtxt<'_>,
     impl_def_id: LocalDefId,
     trait_def_id: DefId,
-) {
+) -> Result<(), ErrorGuaranteed> {
     let impl_header_span = tcx.def_span(impl_def_id);
 
     // Disallow *all* explicit impls of traits marked `#[rustc_deny_explicit_impl]`
@@ -59,18 +64,17 @@ fn enforce_trait_manually_implementable(
             err.code(error_code!(E0328));
         }
 
-        err.emit();
-        return;
+        return Err(err.emit());
     }
 
     if let ty::trait_def::TraitSpecializationKind::AlwaysApplicable =
         tcx.trait_def(trait_def_id).specialization_kind
     {
         if !tcx.features().specialization && !tcx.features().min_specialization {
-            tcx.dcx().emit_err(errors::SpecializationTrait { span: impl_header_span });
-            return;
+            return Err(tcx.dcx().emit_err(errors::SpecializationTrait { span: impl_header_span }));
         }
     }
+    Ok(())
 }
 
 /// We allow impls of marker traits to overlap, so they can't override impls
@@ -79,22 +83,22 @@ fn enforce_empty_impls_for_marker_traits(
     tcx: TyCtxt<'_>,
     impl_def_id: LocalDefId,
     trait_def_id: DefId,
-) {
+) -> Result<(), ErrorGuaranteed> {
     if !tcx.trait_def(trait_def_id).is_marker {
-        return;
+        return Ok(());
     }
 
     if tcx.associated_item_def_ids(trait_def_id).is_empty() {
-        return;
+        return Ok(());
     }
 
-    struct_span_code_err!(
+    Err(struct_span_code_err!(
         tcx.dcx(),
         tcx.def_span(impl_def_id),
         E0715,
         "impls for marker traits cannot contain items"
     )
-    .emit();
+    .emit())
 }
 
 pub fn provide(providers: &mut Providers) {
@@ -115,23 +119,23 @@ pub fn provide(providers: &mut Providers) {
     };
 }
 
-fn coherent_trait(tcx: TyCtxt<'_>, def_id: DefId) {
+fn coherent_trait(tcx: TyCtxt<'_>, def_id: DefId) -> Result<(), ErrorGuaranteed> {
     // Trigger building the specialization graph for the trait. This will detect and report any
     // overlap errors.
-    tcx.ensure().specialization_graph_of(def_id);
+    let mut res = tcx.ensure().specialization_graph_of(def_id);
 
     let impls = tcx.hir().trait_impls(def_id);
     for &impl_def_id in impls {
         let trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap().instantiate_identity();
 
-        check_impl(tcx, impl_def_id, trait_ref);
-        check_object_overlap(tcx, impl_def_id, trait_ref);
+        res = res.and(check_impl(tcx, impl_def_id, trait_ref));
+        res = res.and(check_object_overlap(tcx, impl_def_id, trait_ref));
 
-        unsafety::check_item(tcx, impl_def_id);
-        tcx.ensure().orphan_check_impl(impl_def_id);
+        res = res.and(unsafety::check_item(tcx, impl_def_id));
+        res = res.and(tcx.ensure().orphan_check_impl(impl_def_id));
     }
 
-    builtin::check_trait(tcx, def_id);
+    res.and(builtin::check_trait(tcx, def_id))
 }
 
 /// Checks whether an impl overlaps with the automatic `impl Trait for dyn Trait`.
@@ -139,12 +143,12 @@ fn check_object_overlap<'tcx>(
     tcx: TyCtxt<'tcx>,
     impl_def_id: LocalDefId,
     trait_ref: ty::TraitRef<'tcx>,
-) {
+) -> Result<(), ErrorGuaranteed> {
     let trait_def_id = trait_ref.def_id;
 
     if trait_ref.references_error() {
         debug!("coherence: skipping impl {:?} with error {:?}", impl_def_id, trait_ref);
-        return;
+        return Ok(());
     }
 
     // check for overlap with the automatic `impl Trait for dyn Trait`
@@ -173,7 +177,7 @@ fn check_object_overlap<'tcx>(
                 let mut supertrait_def_ids = traits::supertrait_def_ids(tcx, component_def_id);
                 if supertrait_def_ids.any(|d| d == trait_def_id) {
                     let span = tcx.def_span(impl_def_id);
-                    struct_span_code_err!(
+                    return Err(struct_span_code_err!(
                         tcx.dcx(),
                         span,
                         E0371,
@@ -189,9 +193,10 @@ fn check_object_overlap<'tcx>(
                             tcx.def_path_str(trait_def_id)
                         ),
                     )
-                    .emit();
+                    .emit());
                 }
             }
         }
     }
+    Ok(())
 }
diff --git a/compiler/rustc_hir_analysis/src/coherence/unsafety.rs b/compiler/rustc_hir_analysis/src/coherence/unsafety.rs
index 7b146573a1b..e4c407af53f 100644
--- a/compiler/rustc_hir_analysis/src/coherence/unsafety.rs
+++ b/compiler/rustc_hir_analysis/src/coherence/unsafety.rs
@@ -6,8 +6,9 @@ use rustc_hir as hir;
 use rustc_hir::Unsafety;
 use rustc_middle::ty::TyCtxt;
 use rustc_span::def_id::LocalDefId;
+use rustc_span::ErrorGuaranteed;
 
-pub(super) fn check_item(tcx: TyCtxt<'_>, def_id: LocalDefId) {
+pub(super) fn check_item(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Result<(), ErrorGuaranteed> {
     let item = tcx.hir().expect_item(def_id);
     let impl_ = item.expect_impl();
 
@@ -18,7 +19,7 @@ pub(super) fn check_item(tcx: TyCtxt<'_>, def_id: LocalDefId) {
             impl_.generics.params.iter().find(|p| p.pure_wrt_drop).map(|_| "may_dangle");
         match (trait_def.unsafety, unsafe_attr, impl_.unsafety, impl_.polarity) {
             (Unsafety::Normal, None, Unsafety::Unsafe, hir::ImplPolarity::Positive) => {
-                struct_span_code_err!(
+                return Err(struct_span_code_err!(
                     tcx.dcx(),
                     tcx.def_span(def_id),
                     E0199,
@@ -31,11 +32,11 @@ pub(super) fn check_item(tcx: TyCtxt<'_>, def_id: LocalDefId) {
                     "",
                     rustc_errors::Applicability::MachineApplicable,
                 )
-                .emit();
+                .emit());
             }
 
             (Unsafety::Unsafe, _, Unsafety::Normal, hir::ImplPolarity::Positive) => {
-                struct_span_code_err!(
+                return Err(struct_span_code_err!(
                     tcx.dcx(),
                     tcx.def_span(def_id),
                     E0200,
@@ -54,11 +55,11 @@ pub(super) fn check_item(tcx: TyCtxt<'_>, def_id: LocalDefId) {
                     "unsafe ",
                     rustc_errors::Applicability::MaybeIncorrect,
                 )
-                .emit();
+                .emit());
             }
 
             (Unsafety::Normal, Some(attr_name), Unsafety::Normal, hir::ImplPolarity::Positive) => {
-                struct_span_code_err!(
+                return Err(struct_span_code_err!(
                     tcx.dcx(),
                     tcx.def_span(def_id),
                     E0569,
@@ -77,7 +78,7 @@ pub(super) fn check_item(tcx: TyCtxt<'_>, def_id: LocalDefId) {
                     "unsafe ",
                     rustc_errors::Applicability::MaybeIncorrect,
                 )
-                .emit();
+                .emit());
             }
 
             (_, _, Unsafety::Unsafe, hir::ImplPolarity::Negative(_)) => {
@@ -92,4 +93,5 @@ pub(super) fn check_item(tcx: TyCtxt<'_>, def_id: LocalDefId) {
             }
         }
     }
+    Ok(())
 }
diff --git a/compiler/rustc_hir_analysis/src/lib.rs b/compiler/rustc_hir_analysis/src/lib.rs
index 0a3a71ba1a2..ad5b6664677 100644
--- a/compiler/rustc_hir_analysis/src/lib.rs
+++ b/compiler/rustc_hir_analysis/src/lib.rs
@@ -172,19 +172,15 @@ pub fn check_crate(tcx: TyCtxt<'_>) -> Result<(), ErrorGuaranteed> {
 
     tcx.sess.time("coherence_checking", || {
         // Check impls constrain their parameters
-        let res =
+        let mut res =
             tcx.hir().try_par_for_each_module(|module| tcx.ensure().check_mod_impl_wf(module));
 
-        // FIXME(matthewjasper) We shouldn't need to use `track_errors` anywhere in this function
-        // or the compiler in general.
-        res.and(tcx.sess.track_errors(|| {
-            for &trait_def_id in tcx.all_local_trait_impls(()).keys() {
-                tcx.ensure().coherent_trait(trait_def_id);
-            }
-        }))
+        for &trait_def_id in tcx.all_local_trait_impls(()).keys() {
+            res = res.and(tcx.ensure().coherent_trait(trait_def_id));
+        }
         // these queries are executed for side-effects (error reporting):
-        .and(tcx.ensure().crate_inherent_impls(()))
-        .and(tcx.ensure().crate_inherent_impls_overlap_check(()))
+        res.and(tcx.ensure().crate_inherent_impls(()))
+            .and(tcx.ensure().crate_inherent_impls_overlap_check(()))
     })?;
 
     if tcx.features().rustc_attrs {
diff --git a/compiler/rustc_hir_typeck/src/callee.rs b/compiler/rustc_hir_typeck/src/callee.rs
index d486f069989..9dc365526d4 100644
--- a/compiler/rustc_hir_typeck/src/callee.rs
+++ b/compiler/rustc_hir_typeck/src/callee.rs
@@ -220,6 +220,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             (self.tcx.lang_items().fn_trait(), Ident::with_dummy_span(sym::call), true),
             (self.tcx.lang_items().fn_mut_trait(), Ident::with_dummy_span(sym::call_mut), true),
             (self.tcx.lang_items().fn_once_trait(), Ident::with_dummy_span(sym::call_once), false),
+            (self.tcx.lang_items().async_fn_trait(), Ident::with_dummy_span(sym::async_call), true),
+            (
+                self.tcx.lang_items().async_fn_mut_trait(),
+                Ident::with_dummy_span(sym::async_call_mut),
+                true,
+            ),
+            (
+                self.tcx.lang_items().async_fn_once_trait(),
+                Ident::with_dummy_span(sym::async_call_once),
+                false,
+            ),
         ] {
             let Some(trait_def_id) = opt_trait_def_id else { continue };
 
diff --git a/compiler/rustc_infer/src/infer/error_reporting/note_and_explain.rs b/compiler/rustc_infer/src/infer/error_reporting/note_and_explain.rs
index 01cd3c57925..21ea48c6c83 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/note_and_explain.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/note_and_explain.rs
@@ -294,6 +294,75 @@ impl<T> Trait<T> for X {
                             );
                         }
                     }
+                    (ty::Dynamic(t, _, ty::DynKind::Dyn), ty::Alias(ty::Opaque, alias))
+                        if let Some(def_id) = t.principal_def_id()
+                            && tcx.explicit_item_bounds(alias.def_id).skip_binder().iter().any(
+                                |(pred, _span)| match pred.kind().skip_binder() {
+                                    ty::ClauseKind::Trait(trait_predicate)
+                                        if trait_predicate.polarity
+                                            == ty::ImplPolarity::Positive =>
+                                    {
+                                        trait_predicate.def_id() == def_id
+                                    }
+                                    _ => false,
+                                },
+                            ) =>
+                    {
+                        diag.help(format!(
+                            "you can box the `{}` to coerce it to `Box<{}>`, but you'll have to \
+                             change the expected type as well",
+                            values.found, values.expected,
+                        ));
+                    }
+                    (ty::Dynamic(t, _, ty::DynKind::Dyn), _)
+                        if let Some(def_id) = t.principal_def_id() =>
+                    {
+                        let mut impl_def_ids = vec![];
+                        tcx.for_each_relevant_impl(def_id, values.found, |did| {
+                            impl_def_ids.push(did)
+                        });
+                        if let [_] = &impl_def_ids[..] {
+                            let trait_name = tcx.item_name(def_id);
+                            diag.help(format!(
+                                "`{}` implements `{trait_name}` so you could box the found value \
+                                 and coerce it to the trait object `Box<dyn {trait_name}>`, you \
+                                 will have to change the expected type as well",
+                                values.found,
+                            ));
+                        }
+                    }
+                    (_, ty::Dynamic(t, _, ty::DynKind::Dyn))
+                        if let Some(def_id) = t.principal_def_id() =>
+                    {
+                        let mut impl_def_ids = vec![];
+                        tcx.for_each_relevant_impl(def_id, values.expected, |did| {
+                            impl_def_ids.push(did)
+                        });
+                        if let [_] = &impl_def_ids[..] {
+                            let trait_name = tcx.item_name(def_id);
+                            diag.help(format!(
+                                "`{}` implements `{trait_name}` so you could change the expected \
+                                 type to `Box<dyn {trait_name}>`",
+                                values.expected,
+                            ));
+                        }
+                    }
+                    (ty::Dynamic(t, _, ty::DynKind::DynStar), _)
+                        if let Some(def_id) = t.principal_def_id() =>
+                    {
+                        let mut impl_def_ids = vec![];
+                        tcx.for_each_relevant_impl(def_id, values.found, |did| {
+                            impl_def_ids.push(did)
+                        });
+                        if let [_] = &impl_def_ids[..] {
+                            let trait_name = tcx.item_name(def_id);
+                            diag.help(format!(
+                                "`{}` implements `{trait_name}`, `#[feature(dyn_star)]` is likely \
+                                 not enabled; that feature it is currently incomplete",
+                                values.found,
+                            ));
+                        }
+                    }
                     (_, ty::Alias(ty::Opaque, opaque_ty))
                     | (ty::Alias(ty::Opaque, opaque_ty), _) => {
                         if opaque_ty.def_id.is_local()
diff --git a/compiler/rustc_macros/src/query.rs b/compiler/rustc_macros/src/query.rs
index ad1980136f3..25675e06e38 100644
--- a/compiler/rustc_macros/src/query.rs
+++ b/compiler/rustc_macros/src/query.rs
@@ -120,7 +120,8 @@ struct QueryModifiers {
 
     /// Forward the result on ensure if the query gets recomputed, and
     /// return `Ok(())` otherwise. Only applicable to queries returning
-    /// `Result<(), ErrorGuaranteed>`
+    /// `Result<T, ErrorGuaranteed>`. The `T` is not returned from `ensure`
+    /// invocations.
     ensure_forwards_result_if_red: Option<Ident>,
 }
 
diff --git a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
index c3d6c21c402..0b352a02b64 100644
--- a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
+++ b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
@@ -236,7 +236,14 @@ provide! { tcx, def_id, other, cdata,
     impl_polarity => { table_direct }
     defaultness => { table_direct }
     constness => { table_direct }
-    coerce_unsized_info => { table }
+    coerce_unsized_info => {
+        Ok(cdata
+            .root
+            .tables
+            .coerce_unsized_info
+            .get(cdata, def_id.index)
+            .map(|lazy| lazy.decode((cdata, tcx)))
+            .process_decoded(tcx, || panic!("{def_id:?} does not have coerce_unsized_info"))) }
     mir_const_qualif => { table }
     rendered_const => { table }
     asyncness => { table_direct }
diff --git a/compiler/rustc_metadata/src/rmeta/encoder.rs b/compiler/rustc_metadata/src/rmeta/encoder.rs
index 2d4e49e27d9..542caf86223 100644
--- a/compiler/rustc_metadata/src/rmeta/encoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/encoder.rs
@@ -1994,7 +1994,7 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                 // if this is an impl of `CoerceUnsized`, create its
                 // "unsized info", else just store None
                 if Some(trait_ref.def_id) == tcx.lang_items().coerce_unsized_trait() {
-                    let coerce_unsized_info = tcx.coerce_unsized_info(def_id);
+                    let coerce_unsized_info = tcx.coerce_unsized_info(def_id).unwrap();
                     record!(self.tables.coerce_unsized_info[def_id] <- coerce_unsized_info);
                 }
             }
diff --git a/compiler/rustc_middle/src/mir/interpret/error.rs b/compiler/rustc_middle/src/mir/interpret/error.rs
index 1c9b4e558f0..7a1df495451 100644
--- a/compiler/rustc_middle/src/mir/interpret/error.rs
+++ b/compiler/rustc_middle/src/mir/interpret/error.rs
@@ -200,8 +200,6 @@ pub enum InvalidProgramInfo<'tcx> {
     /// (which unfortunately typeck does not reject).
     /// Not using `FnAbiError` as that contains a nested `LayoutError`.
     FnAbiAdjustForForeignAbi(call::AdjustForForeignAbiError),
-    /// We are runnning into a nonsense situation due to ConstProp violating our invariants.
-    ConstPropNonsense,
 }
 
 /// Details of why a pointer had to be in-bounds.
diff --git a/compiler/rustc_middle/src/query/erase.rs b/compiler/rustc_middle/src/query/erase.rs
index 778b4308d2e..1b01df6a187 100644
--- a/compiler/rustc_middle/src/query/erase.rs
+++ b/compiler/rustc_middle/src/query/erase.rs
@@ -1,6 +1,7 @@
 use crate::mir;
 use crate::query::CyclePlaceholder;
 use crate::traits;
+use crate::ty::adjustment::CoerceUnsizedInfo;
 use crate::ty::{self, Ty};
 use std::intrinsics::transmute_unchecked;
 use std::mem::{size_of, MaybeUninit};
@@ -105,6 +106,10 @@ impl EraseType for Result<Option<ty::Instance<'_>>, rustc_errors::ErrorGuarantee
         [u8; size_of::<Result<Option<ty::Instance<'static>>, rustc_errors::ErrorGuaranteed>>()];
 }
 
+impl EraseType for Result<CoerceUnsizedInfo, rustc_errors::ErrorGuaranteed> {
+    type Result = [u8; size_of::<Result<CoerceUnsizedInfo, rustc_errors::ErrorGuaranteed>>()];
+}
+
 impl EraseType for Result<Option<ty::EarlyBinder<ty::Const<'_>>>, rustc_errors::ErrorGuaranteed> {
     type Result = [u8; size_of::<
         Result<Option<ty::EarlyBinder<ty::Const<'static>>>, rustc_errors::ErrorGuaranteed>,
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 23daefd5a65..2f7ae68c692 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -977,10 +977,11 @@ rustc_queries! {
     }
 
     /// Caches `CoerceUnsized` kinds for impls on custom types.
-    query coerce_unsized_info(key: DefId) -> ty::adjustment::CoerceUnsizedInfo {
+    query coerce_unsized_info(key: DefId) -> Result<ty::adjustment::CoerceUnsizedInfo, ErrorGuaranteed> {
         desc { |tcx| "computing CoerceUnsized info for `{}`", tcx.def_path_str(key) }
         cache_on_disk_if { key.is_local() }
         separate_provide_extern
+        ensure_forwards_result_if_red
     }
 
     query typeck(key: LocalDefId) -> &'tcx ty::TypeckResults<'tcx> {
@@ -1000,8 +1001,9 @@ rustc_queries! {
         desc { |tcx| "checking whether `{}` has a body", tcx.def_path_str(def_id) }
     }
 
-    query coherent_trait(def_id: DefId) -> () {
+    query coherent_trait(def_id: DefId) -> Result<(), ErrorGuaranteed> {
         desc { |tcx| "coherence checking all impls of trait `{}`", tcx.def_path_str(def_id) }
+        ensure_forwards_result_if_red
     }
 
     /// Borrow-checks the function body. If this is a closure, returns
@@ -1032,6 +1034,7 @@ rustc_queries! {
             "checking whether impl `{}` follows the orphan rules",
             tcx.def_path_str(key),
         }
+        ensure_forwards_result_if_red
     }
 
     /// Check whether the function has any recursion that could cause the inliner to trigger
@@ -1300,6 +1303,7 @@ rustc_queries! {
     query specialization_graph_of(trait_id: DefId) -> Result<&'tcx specialization_graph::Graph, ErrorGuaranteed> {
         desc { |tcx| "building specialization graph of trait `{}`", tcx.def_path_str(trait_id) }
         cache_on_disk_if { true }
+        ensure_forwards_result_if_red
     }
     query object_safety_violations(trait_id: DefId) -> &'tcx [ObjectSafetyViolation] {
         desc { |tcx| "determining object safety of trait `{}`", tcx.def_path_str(trait_id) }
diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs
index ef621f29bfd..1f81678d6a5 100644
--- a/compiler/rustc_middle/src/ty/util.rs
+++ b/compiler/rustc_middle/src/ty/util.rs
@@ -350,7 +350,7 @@ impl<'tcx> TyCtxt<'tcx> {
         validate: impl Fn(Self, DefId) -> Result<(), ErrorGuaranteed>,
     ) -> Option<ty::Destructor> {
         let drop_trait = self.lang_items().drop_trait()?;
-        self.ensure().coherent_trait(drop_trait);
+        self.ensure().coherent_trait(drop_trait).ok()?;
 
         let ty = self.type_of(adt_did).instantiate_identity();
         let mut dtor_candidate = None;
diff --git a/compiler/rustc_mir_transform/src/const_prop.rs b/compiler/rustc_mir_transform/src/const_prop.rs
index c5824c30770..8b9e507c8c7 100644
--- a/compiler/rustc_mir_transform/src/const_prop.rs
+++ b/compiler/rustc_mir_transform/src/const_prop.rs
@@ -1,21 +1,12 @@
 //! Propagates constants for early reporting of statically known
 //! assertion failures
 
-use rustc_const_eval::interpret::{
-    self, compile_time_machine, AllocId, ConstAllocation, FnArg, Frame, ImmTy, InterpCx,
-    InterpResult, OpTy, PlaceTy, Pointer,
-};
-use rustc_data_structures::fx::FxHashSet;
 use rustc_index::bit_set::BitSet;
 use rustc_index::IndexVec;
 use rustc_middle::mir::visit::{MutatingUseContext, NonMutatingUseContext, PlaceContext, Visitor};
 use rustc_middle::mir::*;
-use rustc_middle::query::TyCtxtAt;
-use rustc_middle::ty::layout::TyAndLayout;
-use rustc_middle::ty::{self, ParamEnv, TyCtxt};
-use rustc_span::def_id::DefId;
+use rustc_middle::ty::{ParamEnv, TyCtxt};
 use rustc_target::abi::Size;
-use rustc_target::spec::abi::Abi as CallAbi;
 
 /// The maximum number of bytes that we'll allocate space for a local or the return value.
 /// Needed for #66397, because otherwise we eval into large places and that can cause OOM or just
@@ -49,162 +40,6 @@ pub(crate) macro throw_machine_stop_str($($tt:tt)*) {{
     throw_machine_stop!(Zst)
 }}
 
-pub(crate) struct ConstPropMachine<'mir, 'tcx> {
-    /// The virtual call stack.
-    stack: Vec<Frame<'mir, 'tcx>>,
-    pub written_only_inside_own_block_locals: FxHashSet<Local>,
-    pub can_const_prop: IndexVec<Local, ConstPropMode>,
-}
-
-impl ConstPropMachine<'_, '_> {
-    pub fn new(can_const_prop: IndexVec<Local, ConstPropMode>) -> Self {
-        Self {
-            stack: Vec::new(),
-            written_only_inside_own_block_locals: Default::default(),
-            can_const_prop,
-        }
-    }
-}
-
-impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for ConstPropMachine<'mir, 'tcx> {
-    compile_time_machine!(<'mir, 'tcx>);
-
-    const PANIC_ON_ALLOC_FAIL: bool = true; // all allocations are small (see `MAX_ALLOC_LIMIT`)
-
-    const POST_MONO_CHECKS: bool = false; // this MIR is still generic!
-
-    type MemoryKind = !;
-
-    #[inline(always)]
-    fn enforce_alignment(_ecx: &InterpCx<'mir, 'tcx, Self>) -> bool {
-        false // no reason to enforce alignment
-    }
-
-    #[inline(always)]
-    fn enforce_validity(_ecx: &InterpCx<'mir, 'tcx, Self>, _layout: TyAndLayout<'tcx>) -> bool {
-        false // for now, we don't enforce validity
-    }
-
-    fn load_mir(
-        _ecx: &InterpCx<'mir, 'tcx, Self>,
-        _instance: ty::InstanceDef<'tcx>,
-    ) -> InterpResult<'tcx, &'tcx Body<'tcx>> {
-        throw_machine_stop_str!("calling functions isn't supported in ConstProp")
-    }
-
-    fn panic_nounwind(_ecx: &mut InterpCx<'mir, 'tcx, Self>, _msg: &str) -> InterpResult<'tcx> {
-        throw_machine_stop_str!("panicking isn't supported in ConstProp")
-    }
-
-    fn find_mir_or_eval_fn(
-        _ecx: &mut InterpCx<'mir, 'tcx, Self>,
-        _instance: ty::Instance<'tcx>,
-        _abi: CallAbi,
-        _args: &[FnArg<'tcx>],
-        _destination: &PlaceTy<'tcx>,
-        _target: Option<BasicBlock>,
-        _unwind: UnwindAction,
-    ) -> InterpResult<'tcx, Option<(&'mir Body<'tcx>, ty::Instance<'tcx>)>> {
-        Ok(None)
-    }
-
-    fn call_intrinsic(
-        _ecx: &mut InterpCx<'mir, 'tcx, Self>,
-        _instance: ty::Instance<'tcx>,
-        _args: &[OpTy<'tcx>],
-        _destination: &PlaceTy<'tcx>,
-        _target: Option<BasicBlock>,
-        _unwind: UnwindAction,
-    ) -> InterpResult<'tcx> {
-        throw_machine_stop_str!("calling intrinsics isn't supported in ConstProp")
-    }
-
-    fn assert_panic(
-        _ecx: &mut InterpCx<'mir, 'tcx, Self>,
-        _msg: &rustc_middle::mir::AssertMessage<'tcx>,
-        _unwind: rustc_middle::mir::UnwindAction,
-    ) -> InterpResult<'tcx> {
-        bug!("panics terminators are not evaluated in ConstProp")
-    }
-
-    fn binary_ptr_op(
-        _ecx: &InterpCx<'mir, 'tcx, Self>,
-        _bin_op: BinOp,
-        _left: &ImmTy<'tcx>,
-        _right: &ImmTy<'tcx>,
-    ) -> InterpResult<'tcx, (ImmTy<'tcx>, bool)> {
-        // We can't do this because aliasing of memory can differ between const eval and llvm
-        throw_machine_stop_str!("pointer arithmetic or comparisons aren't supported in ConstProp")
-    }
-
-    fn before_access_local_mut<'a>(
-        ecx: &'a mut InterpCx<'mir, 'tcx, Self>,
-        frame: usize,
-        local: Local,
-    ) -> InterpResult<'tcx> {
-        assert_eq!(frame, 0);
-        match ecx.machine.can_const_prop[local] {
-            ConstPropMode::NoPropagation => {
-                throw_machine_stop_str!(
-                    "tried to write to a local that is marked as not propagatable"
-                )
-            }
-            ConstPropMode::OnlyInsideOwnBlock => {
-                ecx.machine.written_only_inside_own_block_locals.insert(local);
-            }
-            ConstPropMode::FullConstProp => {}
-        }
-        Ok(())
-    }
-
-    fn before_access_global(
-        _tcx: TyCtxtAt<'tcx>,
-        _machine: &Self,
-        _alloc_id: AllocId,
-        alloc: ConstAllocation<'tcx>,
-        _static_def_id: Option<DefId>,
-        is_write: bool,
-    ) -> InterpResult<'tcx> {
-        if is_write {
-            throw_machine_stop_str!("can't write to global");
-        }
-        // If the static allocation is mutable, then we can't const prop it as its content
-        // might be different at runtime.
-        if alloc.inner().mutability.is_mut() {
-            throw_machine_stop_str!("can't access mutable globals in ConstProp");
-        }
-
-        Ok(())
-    }
-
-    #[inline(always)]
-    fn expose_ptr(_ecx: &mut InterpCx<'mir, 'tcx, Self>, _ptr: Pointer) -> InterpResult<'tcx> {
-        throw_machine_stop_str!("exposing pointers isn't supported in ConstProp")
-    }
-
-    #[inline(always)]
-    fn init_frame_extra(
-        _ecx: &mut InterpCx<'mir, 'tcx, Self>,
-        frame: Frame<'mir, 'tcx>,
-    ) -> InterpResult<'tcx, Frame<'mir, 'tcx>> {
-        Ok(frame)
-    }
-
-    #[inline(always)]
-    fn stack<'a>(
-        ecx: &'a InterpCx<'mir, 'tcx, Self>,
-    ) -> &'a [Frame<'mir, 'tcx, Self::Provenance, Self::FrameExtra>] {
-        &ecx.machine.stack
-    }
-
-    #[inline(always)]
-    fn stack_mut<'a>(
-        ecx: &'a mut InterpCx<'mir, 'tcx, Self>,
-    ) -> &'a mut Vec<Frame<'mir, 'tcx, Self::Provenance, Self::FrameExtra>> {
-        &mut ecx.machine.stack
-    }
-}
-
 /// The mode that `ConstProp` is allowed to run in for a given `Local`.
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub enum ConstPropMode {
diff --git a/compiler/rustc_mir_transform/src/const_prop_lint.rs b/compiler/rustc_mir_transform/src/const_prop_lint.rs
index b8fecaf635a..aa22b8c7c58 100644
--- a/compiler/rustc_mir_transform/src/const_prop_lint.rs
+++ b/compiler/rustc_mir_transform/src/const_prop_lint.rs
@@ -3,37 +3,26 @@
 
 use std::fmt::Debug;
 
-use either::Left;
-
-use rustc_const_eval::interpret::Immediate;
-use rustc_const_eval::interpret::{
-    InterpCx, InterpResult, MemoryKind, OpTy, Scalar, StackPopCleanup,
-};
-use rustc_const_eval::ReportErrorExt;
+use rustc_const_eval::interpret::{ImmTy, Projectable};
+use rustc_const_eval::interpret::{InterpCx, InterpResult, Scalar};
+use rustc_data_structures::fx::FxHashSet;
 use rustc_hir::def::DefKind;
 use rustc_hir::HirId;
 use rustc_index::bit_set::BitSet;
+use rustc_index::{Idx, IndexVec};
 use rustc_middle::mir::visit::Visitor;
 use rustc_middle::mir::*;
 use rustc_middle::ty::layout::{LayoutError, LayoutOf, LayoutOfHelpers, TyAndLayout};
-use rustc_middle::ty::GenericArgs;
-use rustc_middle::ty::{
-    self, ConstInt, Instance, ParamEnv, ScalarInt, Ty, TyCtxt, TypeVisitableExt,
-};
+use rustc_middle::ty::{self, ConstInt, ParamEnv, ScalarInt, Ty, TyCtxt, TypeVisitableExt};
 use rustc_span::Span;
-use rustc_target::abi::{HasDataLayout, Size, TargetDataLayout};
+use rustc_target::abi::{Abi, FieldIdx, HasDataLayout, Size, TargetDataLayout, VariantIdx};
 
 use crate::const_prop::CanConstProp;
-use crate::const_prop::ConstPropMachine;
 use crate::const_prop::ConstPropMode;
-use crate::errors::AssertLint;
+use crate::dataflow_const_prop::DummyMachine;
+use crate::errors::{AssertLint, AssertLintKind};
 use crate::MirLint;
 
-/// The maximum number of bytes that we'll allocate space for a local or the return value.
-/// Needed for #66397, because otherwise we eval into large places and that can cause OOM or just
-/// Severely regress performance.
-const MAX_ALLOC_LIMIT: u64 = 1024;
-
 pub struct ConstPropLint;
 
 impl<'tcx> MirLint<'tcx> for ConstPropLint {
@@ -81,11 +70,85 @@ impl<'tcx> MirLint<'tcx> for ConstPropLint {
 
 /// Finds optimization opportunities on the MIR.
 struct ConstPropagator<'mir, 'tcx> {
-    ecx: InterpCx<'mir, 'tcx, ConstPropMachine<'mir, 'tcx>>,
+    ecx: InterpCx<'mir, 'tcx, DummyMachine>,
     tcx: TyCtxt<'tcx>,
     param_env: ParamEnv<'tcx>,
     worklist: Vec<BasicBlock>,
     visited_blocks: BitSet<BasicBlock>,
+    locals: IndexVec<Local, Value<'tcx>>,
+    body: &'mir Body<'tcx>,
+    written_only_inside_own_block_locals: FxHashSet<Local>,
+    can_const_prop: IndexVec<Local, ConstPropMode>,
+}
+
+#[derive(Debug, Clone)]
+enum Value<'tcx> {
+    Immediate(ImmTy<'tcx>),
+    Aggregate { variant: VariantIdx, fields: IndexVec<FieldIdx, Value<'tcx>> },
+    Uninit,
+}
+
+impl<'tcx> From<ImmTy<'tcx>> for Value<'tcx> {
+    fn from(v: ImmTy<'tcx>) -> Self {
+        Self::Immediate(v)
+    }
+}
+
+impl<'tcx> Value<'tcx> {
+    fn project(
+        &self,
+        proj: &[PlaceElem<'tcx>],
+        prop: &ConstPropagator<'_, 'tcx>,
+    ) -> Option<&Value<'tcx>> {
+        let mut this = self;
+        for proj in proj {
+            this = match (*proj, this) {
+                (PlaceElem::Field(idx, _), Value::Aggregate { fields, .. }) => {
+                    fields.get(idx).unwrap_or(&Value::Uninit)
+                }
+                (PlaceElem::Index(idx), Value::Aggregate { fields, .. }) => {
+                    let idx = prop.get_const(idx.into())?.immediate()?;
+                    let idx = prop.ecx.read_target_usize(idx).ok()?;
+                    fields.get(FieldIdx::from_u32(idx.try_into().ok()?)).unwrap_or(&Value::Uninit)
+                }
+                (
+                    PlaceElem::ConstantIndex { offset, min_length: _, from_end: false },
+                    Value::Aggregate { fields, .. },
+                ) => fields
+                    .get(FieldIdx::from_u32(offset.try_into().ok()?))
+                    .unwrap_or(&Value::Uninit),
+                _ => return None,
+            };
+        }
+        Some(this)
+    }
+
+    fn project_mut(&mut self, proj: &[PlaceElem<'_>]) -> Option<&mut Value<'tcx>> {
+        let mut this = self;
+        for proj in proj {
+            this = match (proj, this) {
+                (PlaceElem::Field(idx, _), Value::Aggregate { fields, .. }) => {
+                    fields.ensure_contains_elem(*idx, || Value::Uninit)
+                }
+                (PlaceElem::Field(..), val @ Value::Uninit) => {
+                    *val = Value::Aggregate {
+                        variant: VariantIdx::new(0),
+                        fields: Default::default(),
+                    };
+                    val.project_mut(&[*proj])?
+                }
+                _ => return None,
+            };
+        }
+        Some(this)
+    }
+
+    fn immediate(&self) -> Option<&ImmTy<'tcx>> {
+        match self {
+            Value::Immediate(op) => Some(op),
+            _ => None,
+        }
+    }
 }
 
 impl<'tcx> LayoutOfHelpers<'tcx> for ConstPropagator<'_, 'tcx> {
@@ -121,49 +184,10 @@ impl<'tcx> ty::layout::HasParamEnv<'tcx> for ConstPropagator<'_, 'tcx> {
 impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
     fn new(body: &'mir Body<'tcx>, tcx: TyCtxt<'tcx>) -> ConstPropagator<'mir, 'tcx> {
         let def_id = body.source.def_id();
-        let args = &GenericArgs::identity_for_item(tcx, def_id);
         let param_env = tcx.param_env_reveal_all_normalized(def_id);
 
         let can_const_prop = CanConstProp::check(tcx, param_env, body);
-        let mut ecx = InterpCx::new(
-            tcx,
-            tcx.def_span(def_id),
-            param_env,
-            ConstPropMachine::new(can_const_prop),
-        );
-
-        let ret_layout = ecx
-            .layout_of(body.bound_return_ty().instantiate(tcx, args))
-            .ok()
-            // Don't bother allocating memory for large values.
-            // I don't know how return types can seem to be unsized but this happens in the
-            // `type/type-unsatisfiable.rs` test.
-            .filter(|ret_layout| {
-                ret_layout.is_sized() && ret_layout.size < Size::from_bytes(MAX_ALLOC_LIMIT)
-            })
-            .unwrap_or_else(|| ecx.layout_of(tcx.types.unit).unwrap());
-
-        let ret = ecx
-            .allocate(ret_layout, MemoryKind::Stack)
-            .expect("couldn't perform small allocation")
-            .into();
-
-        ecx.push_stack_frame(
-            Instance::new(def_id, args),
-            body,
-            &ret,
-            StackPopCleanup::Root { cleanup: false },
-        )
-        .expect("failed to push initial stack frame");
-
-        for local in body.local_decls.indices() {
-            // Mark everything initially live.
-            // This is somewhat dicey since some of them might be unsized and it is incoherent to
-            // mark those as live... We rely on `local_to_place`/`local_to_op` in the interpreter
-            // stopping us before those unsized immediates can cause issues deeper in the
-            // interpreter.
-            ecx.frame_mut().locals[local].make_live_uninit();
-        }
+        let ecx = InterpCx::new(tcx, tcx.def_span(def_id), param_env, DummyMachine);
 
         ConstPropagator {
             ecx,
@@ -171,61 +195,47 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
             param_env,
             worklist: vec![START_BLOCK],
             visited_blocks: BitSet::new_empty(body.basic_blocks.len()),
+            locals: IndexVec::from_elem_n(Value::Uninit, body.local_decls.len()),
+            body,
+            can_const_prop,
+            written_only_inside_own_block_locals: Default::default(),
         }
     }
 
-    fn body(&self) -> &'mir Body<'tcx> {
-        self.ecx.frame().body
-    }
-
     fn local_decls(&self) -> &'mir LocalDecls<'tcx> {
-        &self.body().local_decls
+        &self.body.local_decls
     }
 
-    fn get_const(&self, place: Place<'tcx>) -> Option<OpTy<'tcx>> {
-        let op = match self.ecx.eval_place_to_op(place, None) {
-            Ok(op) => {
-                if op
-                    .as_mplace_or_imm()
-                    .right()
-                    .is_some_and(|imm| matches!(*imm, Immediate::Uninit))
-                {
-                    // Make sure nobody accidentally uses this value.
-                    return None;
-                }
-                op
-            }
-            Err(e) => {
-                trace!("get_const failed: {:?}", e.into_kind().debug());
-                return None;
-            }
-        };
-
-        // Try to read the local as an immediate so that if it is representable as a scalar, we can
-        // handle it as such, but otherwise, just return the value as is.
-        Some(match self.ecx.read_immediate_raw(&op) {
-            Ok(Left(imm)) => imm.into(),
-            _ => op,
-        })
+    fn get_const(&self, place: Place<'tcx>) -> Option<&Value<'tcx>> {
+        self.locals[place.local].project(&place.projection, self)
     }
 
     /// Remove `local` from the pool of `Locals`. Allows writing to them,
     /// but not reading from them anymore.
-    fn remove_const(ecx: &mut InterpCx<'mir, 'tcx, ConstPropMachine<'mir, 'tcx>>, local: Local) {
-        ecx.frame_mut().locals[local].make_live_uninit();
-        ecx.machine.written_only_inside_own_block_locals.remove(&local);
+    fn remove_const(&mut self, local: Local) {
+        self.locals[local] = Value::Uninit;
+        self.written_only_inside_own_block_locals.remove(&local);
+    }
+
+    fn access_mut(&mut self, place: &Place<'_>) -> Option<&mut Value<'tcx>> {
+        match self.can_const_prop[place.local] {
+            ConstPropMode::NoPropagation => return None,
+            ConstPropMode::OnlyInsideOwnBlock => {
+                self.written_only_inside_own_block_locals.insert(place.local);
+            }
+            ConstPropMode::FullConstProp => {}
+        }
+        self.locals[place.local].project_mut(place.projection)
     }
 
     fn lint_root(&self, source_info: SourceInfo) -> Option<HirId> {
-        source_info.scope.lint_root(&self.body().source_scopes)
+        source_info.scope.lint_root(&self.body.source_scopes)
     }
 
-    fn use_ecx<F, T>(&mut self, location: Location, f: F) -> Option<T>
+    fn use_ecx<F, T>(&mut self, f: F) -> Option<T>
     where
         F: FnOnce(&mut Self) -> InterpResult<'tcx, T>,
     {
-        // Overwrite the PC -- whatever the interpreter does to it does not make any sense anyway.
-        self.ecx.frame_mut().loc = Left(location);
         match f(self) {
             Ok(val) => Some(val),
             Err(error) => {
@@ -244,7 +254,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
     }
 
     /// Returns the value, if any, of evaluating `c`.
-    fn eval_constant(&mut self, c: &ConstOperand<'tcx>, location: Location) -> Option<OpTy<'tcx>> {
+    fn eval_constant(&mut self, c: &ConstOperand<'tcx>) -> Option<ImmTy<'tcx>> {
         // FIXME we need to revisit this for #67176
         if c.has_param() {
             return None;
@@ -258,46 +268,62 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
         // manually normalized.
         let val = self.tcx.try_normalize_erasing_regions(self.param_env, c.const_).ok()?;
 
-        self.use_ecx(location, |this| this.ecx.eval_mir_constant(&val, Some(c.span), None))
+        self.use_ecx(|this| this.ecx.eval_mir_constant(&val, Some(c.span), None))?
+            .as_mplace_or_imm()
+            .right()
     }
 
     /// Returns the value, if any, of evaluating `place`.
-    fn eval_place(&mut self, place: Place<'tcx>, location: Location) -> Option<OpTy<'tcx>> {
-        trace!("eval_place(place={:?})", place);
-        self.use_ecx(location, |this| this.ecx.eval_place_to_op(place, None))
+    #[instrument(level = "trace", skip(self), ret)]
+    fn eval_place(&mut self, place: Place<'tcx>) -> Option<ImmTy<'tcx>> {
+        match self.get_const(place)? {
+            Value::Immediate(imm) => Some(imm.clone()),
+            Value::Aggregate { .. } => None,
+            Value::Uninit => None,
+        }
     }
 
     /// Returns the value, if any, of evaluating `op`. Calls upon `eval_constant`
     /// or `eval_place`, depending on the variant of `Operand` used.
-    fn eval_operand(&mut self, op: &Operand<'tcx>, location: Location) -> Option<OpTy<'tcx>> {
+    fn eval_operand(&mut self, op: &Operand<'tcx>) -> Option<ImmTy<'tcx>> {
         match *op {
-            Operand::Constant(ref c) => self.eval_constant(c, location),
-            Operand::Move(place) | Operand::Copy(place) => self.eval_place(place, location),
+            Operand::Constant(ref c) => self.eval_constant(c),
+            Operand::Move(place) | Operand::Copy(place) => self.eval_place(place),
         }
     }
 
-    fn report_assert_as_lint(&self, source_info: &SourceInfo, lint: AssertLint<impl Debug>) {
+    fn report_assert_as_lint(
+        &self,
+        location: Location,
+        lint_kind: AssertLintKind,
+        assert_kind: AssertKind<impl Debug>,
+    ) {
+        let source_info = self.body.source_info(location);
         if let Some(lint_root) = self.lint_root(*source_info) {
-            self.tcx.emit_node_span_lint(lint.lint(), lint_root, source_info.span, lint);
+            let span = source_info.span;
+            self.tcx.emit_node_span_lint(
+                lint_kind.lint(),
+                lint_root,
+                span,
+                AssertLint { span, assert_kind, lint_kind },
+            );
         }
     }
 
     fn check_unary_op(&mut self, op: UnOp, arg: &Operand<'tcx>, location: Location) -> Option<()> {
-        if let (val, true) = self.use_ecx(location, |this| {
-            let val = this.ecx.read_immediate(&this.ecx.eval_operand(arg, None)?)?;
+        let arg = self.eval_operand(arg)?;
+        if let (val, true) = self.use_ecx(|this| {
+            let val = this.ecx.read_immediate(&arg)?;
             let (_res, overflow) = this.ecx.overflowing_unary_op(op, &val)?;
             Ok((val, overflow))
         })? {
             // `AssertKind` only has an `OverflowNeg` variant, so make sure that is
             // appropriate to use.
             assert_eq!(op, UnOp::Neg, "Neg is the only UnOp that can overflow");
-            let source_info = self.body().source_info(location);
             self.report_assert_as_lint(
-                source_info,
-                AssertLint::ArithmeticOverflow(
-                    source_info.span,
-                    AssertKind::OverflowNeg(val.to_const_int()),
-                ),
+                location,
+                AssertLintKind::ArithmeticOverflow,
+                AssertKind::OverflowNeg(val.to_const_int()),
             );
             return None;
         }
@@ -312,11 +338,10 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
         right: &Operand<'tcx>,
         location: Location,
     ) -> Option<()> {
-        let r = self.use_ecx(location, |this| {
-            this.ecx.read_immediate(&this.ecx.eval_operand(right, None)?)
-        });
-        let l = self
-            .use_ecx(location, |this| this.ecx.read_immediate(&this.ecx.eval_operand(left, None)?));
+        let r =
+            self.eval_operand(right).and_then(|r| self.use_ecx(|this| this.ecx.read_immediate(&r)));
+        let l =
+            self.eval_operand(left).and_then(|l| self.use_ecx(|this| this.ecx.read_immediate(&l)));
         // Check for exceeding shifts *even if* we cannot evaluate the LHS.
         if matches!(op, BinOp::Shr | BinOp::Shl) {
             let r = r.clone()?;
@@ -328,7 +353,6 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
             let r_bits = r.to_scalar().to_bits(right_size).ok();
             if r_bits.is_some_and(|b| b >= left_size.bits() as u128) {
                 debug!("check_binary_op: reporting assert for {:?}", location);
-                let source_info = self.body().source_info(location);
                 let panic = AssertKind::Overflow(
                     op,
                     match l {
@@ -342,27 +366,21 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
                     },
                     r.to_const_int(),
                 );
-                self.report_assert_as_lint(
-                    source_info,
-                    AssertLint::ArithmeticOverflow(source_info.span, panic),
-                );
+                self.report_assert_as_lint(location, AssertLintKind::ArithmeticOverflow, panic);
                 return None;
             }
         }
 
         if let (Some(l), Some(r)) = (l, r) {
             // The remaining operators are handled through `overflowing_binary_op`.
-            if self.use_ecx(location, |this| {
+            if self.use_ecx(|this| {
                 let (_res, overflow) = this.ecx.overflowing_binary_op(op, &l, &r)?;
                 Ok(overflow)
             })? {
-                let source_info = self.body().source_info(location);
                 self.report_assert_as_lint(
-                    source_info,
-                    AssertLint::ArithmeticOverflow(
-                        source_info.span,
-                        AssertKind::Overflow(op, l.to_const_int(), r.to_const_int()),
-                    ),
+                    location,
+                    AssertLintKind::ArithmeticOverflow,
+                    AssertKind::Overflow(op, l.to_const_int(), r.to_const_int()),
                 );
                 return None;
             }
@@ -411,7 +429,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
                 // value the local has right now.
                 // Thus, all locals that have their reference taken
                 // must not take part in propagation.
-                Self::remove_const(&mut self.ecx, place.local);
+                self.remove_const(place.local);
 
                 return None;
             }
@@ -453,17 +471,17 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
         cond: &Operand<'tcx>,
         location: Location,
     ) -> Option<!> {
-        let value = &self.eval_operand(cond, location)?;
+        let value = &self.eval_operand(cond)?;
         trace!("assertion on {:?} should be {:?}", value, expected);
 
         let expected = Scalar::from_bool(expected);
-        let value_const = self.use_ecx(location, |this| this.ecx.read_scalar(value))?;
+        let value_const = self.use_ecx(|this| this.ecx.read_scalar(value))?;
 
         if expected != value_const {
             // Poison all places this operand references so that further code
             // doesn't use the invalid value
             if let Some(place) = cond.place() {
-                Self::remove_const(&mut self.ecx, place.local);
+                self.remove_const(place.local);
             }
 
             enum DbgVal<T> {
@@ -481,7 +499,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
             let mut eval_to_int = |op| {
                 // This can be `None` if the lhs wasn't const propagated and we just
                 // triggered the assert on the value of the rhs.
-                self.eval_operand(op, location)
+                self.eval_operand(op)
                     .and_then(|op| self.ecx.read_immediate(&op).ok())
                     .map_or(DbgVal::Underscore, |op| DbgVal::Val(op.to_const_int()))
             };
@@ -503,11 +521,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
                 // Need proper const propagator for these.
                 _ => return None,
             };
-            let source_info = self.body().source_info(location);
-            self.report_assert_as_lint(
-                source_info,
-                AssertLint::UnconditionalPanic(source_info.span, msg),
-            );
+            self.report_assert_as_lint(location, AssertLintKind::UnconditionalPanic, msg);
         }
 
         None
@@ -515,16 +529,176 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
 
     fn ensure_not_propagated(&self, local: Local) {
         if cfg!(debug_assertions) {
+            let val = self.get_const(local.into());
             assert!(
-                self.get_const(local.into()).is_none()
+                matches!(val, Some(Value::Uninit))
                     || self
                         .layout_of(self.local_decls()[local].ty)
                         .map_or(true, |layout| layout.is_zst()),
-                "failed to remove values for `{local:?}`, value={:?}",
-                self.get_const(local.into()),
+                "failed to remove values for `{local:?}`, value={val:?}",
             )
         }
     }
+
+    #[instrument(level = "trace", skip(self), ret)]
+    fn eval_rvalue(
+        &mut self,
+        rvalue: &Rvalue<'tcx>,
+        location: Location,
+        dest: &Place<'tcx>,
+    ) -> Option<()> {
+        if !dest.projection.is_empty() {
+            return None;
+        }
+        use rustc_middle::mir::Rvalue::*;
+        let layout = self.ecx.layout_of(dest.ty(self.body, self.tcx).ty).ok()?;
+        trace!(?layout);
+
+        let val: Value<'_> = match *rvalue {
+            ThreadLocalRef(_) => return None,
+
+            Use(ref operand) => self.eval_operand(operand)?.into(),
+
+            CopyForDeref(place) => self.eval_place(place)?.into(),
+
+            BinaryOp(bin_op, box (ref left, ref right)) => {
+                let left = self.eval_operand(left)?;
+                let left = self.use_ecx(|this| this.ecx.read_immediate(&left))?;
+
+                let right = self.eval_operand(right)?;
+                let right = self.use_ecx(|this| this.ecx.read_immediate(&right))?;
+
+                let val =
+                    self.use_ecx(|this| this.ecx.wrapping_binary_op(bin_op, &left, &right))?;
+                val.into()
+            }
+
+            CheckedBinaryOp(bin_op, box (ref left, ref right)) => {
+                let left = self.eval_operand(left)?;
+                let left = self.use_ecx(|this| this.ecx.read_immediate(&left))?;
+
+                let right = self.eval_operand(right)?;
+                let right = self.use_ecx(|this| this.ecx.read_immediate(&right))?;
+
+                let (val, overflowed) =
+                    self.use_ecx(|this| this.ecx.overflowing_binary_op(bin_op, &left, &right))?;
+                let overflowed = ImmTy::from_bool(overflowed, self.tcx);
+                Value::Aggregate {
+                    variant: VariantIdx::new(0),
+                    fields: [Value::from(val), overflowed.into()].into_iter().collect(),
+                }
+            }
+
+            UnaryOp(un_op, ref operand) => {
+                let operand = self.eval_operand(operand)?;
+                let val = self.use_ecx(|this| this.ecx.read_immediate(&operand))?;
+
+                let val = self.use_ecx(|this| this.ecx.wrapping_unary_op(un_op, &val))?;
+                val.into()
+            }
+
+            Aggregate(ref kind, ref fields) => Value::Aggregate {
+                fields: fields
+                    .iter()
+                    .map(|field| self.eval_operand(field).map_or(Value::Uninit, Value::Immediate))
+                    .collect(),
+                variant: match **kind {
+                    AggregateKind::Adt(_, variant, _, _, _) => variant,
+                    AggregateKind::Array(_)
+                    | AggregateKind::Tuple
+                    | AggregateKind::Closure(_, _)
+                    | AggregateKind::Coroutine(_, _) => VariantIdx::new(0),
+                },
+            },
+
+            Repeat(ref op, n) => {
+                trace!(?op, ?n);
+                return None;
+            }
+
+            Len(place) => {
+                let len = match self.get_const(place)? {
+                    Value::Immediate(src) => src.len(&self.ecx).ok()?,
+                    Value::Aggregate { fields, .. } => fields.len() as u64,
+                    Value::Uninit => match place.ty(self.local_decls(), self.tcx).ty.kind() {
+                        ty::Array(_, n) => n.try_eval_target_usize(self.tcx, self.param_env)?,
+                        _ => return None,
+                    },
+                };
+                ImmTy::from_scalar(Scalar::from_target_usize(len, self), layout).into()
+            }
+
+            Ref(..) | AddressOf(..) => return None,
+
+            NullaryOp(ref null_op, ty) => {
+                let op_layout = self.use_ecx(|this| this.ecx.layout_of(ty))?;
+                let val = match null_op {
+                    NullOp::SizeOf => op_layout.size.bytes(),
+                    NullOp::AlignOf => op_layout.align.abi.bytes(),
+                    NullOp::OffsetOf(fields) => {
+                        op_layout.offset_of_subfield(self, fields.iter()).bytes()
+                    }
+                };
+                ImmTy::from_scalar(Scalar::from_target_usize(val, self), layout).into()
+            }
+
+            ShallowInitBox(..) => return None,
+
+            Cast(ref kind, ref value, to) => match kind {
+                CastKind::IntToInt | CastKind::IntToFloat => {
+                    let value = self.eval_operand(value)?;
+                    let value = self.ecx.read_immediate(&value).ok()?;
+                    let to = self.ecx.layout_of(to).ok()?;
+                    let res = self.ecx.int_to_int_or_float(&value, to).ok()?;
+                    res.into()
+                }
+                CastKind::FloatToFloat | CastKind::FloatToInt => {
+                    let value = self.eval_operand(value)?;
+                    let value = self.ecx.read_immediate(&value).ok()?;
+                    let to = self.ecx.layout_of(to).ok()?;
+                    let res = self.ecx.float_to_float_or_int(&value, to).ok()?;
+                    res.into()
+                }
+                CastKind::Transmute => {
+                    let value = self.eval_operand(value)?;
+                    let to = self.ecx.layout_of(to).ok()?;
+                    // `offset` for immediates only supports scalar/scalar-pair ABIs,
+                    // so bail out if the target is not one.
+                    match (value.layout.abi, to.abi) {
+                        (Abi::Scalar(..), Abi::Scalar(..)) => {}
+                        (Abi::ScalarPair(..), Abi::ScalarPair(..)) => {}
+                        _ => return None,
+                    }
+
+                    value.offset(Size::ZERO, to, &self.ecx).ok()?.into()
+                }
+                _ => return None,
+            },
+
+            Discriminant(place) => {
+                let variant = match self.get_const(place)? {
+                    Value::Immediate(op) => {
+                        let op = op.clone();
+                        self.use_ecx(|this| this.ecx.read_discriminant(&op))?
+                    }
+                    Value::Aggregate { variant, .. } => *variant,
+                    Value::Uninit => return None,
+                };
+                let imm = self.use_ecx(|this| {
+                    this.ecx.discriminant_for_variant(
+                        place.ty(this.local_decls(), this.tcx).ty,
+                        variant,
+                    )
+                })?;
+                imm.into()
+            }
+        };
+        trace!(?val);
+
+        *self.access_mut(dest)? = val;
+
+        Some(())
+    }
 }
 
 impl<'tcx> Visitor<'tcx> for ConstPropagator<'_, 'tcx> {
@@ -546,7 +720,7 @@ impl<'tcx> Visitor<'tcx> for ConstPropagator<'_, 'tcx> {
     fn visit_constant(&mut self, constant: &ConstOperand<'tcx>, location: Location) {
         trace!("visit_constant: {:?}", constant);
         self.super_constant(constant, location);
-        self.eval_constant(constant, location);
+        self.eval_constant(constant);
     }
 
     fn visit_assign(&mut self, place: &Place<'tcx>, rvalue: &Rvalue<'tcx>, location: Location) {
@@ -554,15 +728,12 @@ impl<'tcx> Visitor<'tcx> for ConstPropagator<'_, 'tcx> {
 
         let Some(()) = self.check_rvalue(rvalue, location) else { return };
 
-        match self.ecx.machine.can_const_prop[place.local] {
+        match self.can_const_prop[place.local] {
             // Do nothing if the place is indirect.
             _ if place.is_indirect() => {}
             ConstPropMode::NoPropagation => self.ensure_not_propagated(place.local),
             ConstPropMode::OnlyInsideOwnBlock | ConstPropMode::FullConstProp => {
-                if self
-                    .use_ecx(location, |this| this.ecx.eval_rvalue_into_place(rvalue, *place))
-                    .is_none()
-                {
+                if self.eval_rvalue(rvalue, location, place).is_none() {
                     // Const prop failed, so erase the destination, ensuring that whatever happens
                     // from here on, does not know about the previous value.
                     // This is important in case we have
@@ -578,7 +749,7 @@ impl<'tcx> Visitor<'tcx> for ConstPropagator<'_, 'tcx> {
                         Nuking the entire site from orbit, it's the only way to be sure",
                         place,
                     );
-                    Self::remove_const(&mut self.ecx, place.local);
+                    self.remove_const(place.local);
                 }
             }
         }
@@ -592,28 +763,24 @@ impl<'tcx> Visitor<'tcx> for ConstPropagator<'_, 'tcx> {
         self.super_statement(statement, location);
 
         match statement.kind {
-            StatementKind::SetDiscriminant { ref place, .. } => {
-                match self.ecx.machine.can_const_prop[place.local] {
+            StatementKind::SetDiscriminant { ref place, variant_index } => {
+                match self.can_const_prop[place.local] {
                     // Do nothing if the place is indirect.
                     _ if place.is_indirect() => {}
                     ConstPropMode::NoPropagation => self.ensure_not_propagated(place.local),
                     ConstPropMode::FullConstProp | ConstPropMode::OnlyInsideOwnBlock => {
-                        if self.use_ecx(location, |this| this.ecx.statement(statement)).is_some() {
-                            trace!("propped discriminant into {:?}", place);
-                        } else {
-                            Self::remove_const(&mut self.ecx, place.local);
+                        match self.access_mut(place) {
+                            Some(Value::Aggregate { variant, .. }) => *variant = variant_index,
+                            _ => self.remove_const(place.local),
                         }
                     }
                 }
             }
             StatementKind::StorageLive(local) => {
-                let frame = self.ecx.frame_mut();
-                frame.locals[local].make_live_uninit();
+                self.remove_const(local);
             }
             StatementKind::StorageDead(local) => {
-                let frame = self.ecx.frame_mut();
-                // We don't actually track liveness, so the local remains live. But forget its value.
-                frame.locals[local].make_live_uninit();
+                self.remove_const(local);
             }
             _ => {}
         }
@@ -626,9 +793,8 @@ impl<'tcx> Visitor<'tcx> for ConstPropagator<'_, 'tcx> {
                 self.check_assertion(*expected, msg, cond, location);
             }
             TerminatorKind::SwitchInt { ref discr, ref targets } => {
-                if let Some(ref value) = self.eval_operand(discr, location)
-                    && let Some(value_const) =
-                        self.use_ecx(location, |this| this.ecx.read_scalar(value))
+                if let Some(ref value) = self.eval_operand(discr)
+                    && let Some(value_const) = self.use_ecx(|this| this.ecx.read_scalar(value))
                     && let Ok(constant) = value_const.try_to_int()
                     && let Ok(constant) = constant.to_bits(constant.size())
                 {
@@ -665,7 +831,7 @@ impl<'tcx> Visitor<'tcx> for ConstPropagator<'_, 'tcx> {
         // which were modified in the current block.
         // Take it out of the ecx so we can get a mutable reference to the ecx for `remove_const`.
         let mut written_only_inside_own_block_locals =
-            std::mem::take(&mut self.ecx.machine.written_only_inside_own_block_locals);
+            std::mem::take(&mut self.written_only_inside_own_block_locals);
 
         // This loop can get very hot for some bodies: it check each local in each bb.
         // To avoid this quadratic behaviour, we only clear the locals that were modified inside
@@ -673,17 +839,13 @@ impl<'tcx> Visitor<'tcx> for ConstPropagator<'_, 'tcx> {
         // The order in which we remove consts does not matter.
         #[allow(rustc::potential_query_instability)]
         for local in written_only_inside_own_block_locals.drain() {
-            debug_assert_eq!(
-                self.ecx.machine.can_const_prop[local],
-                ConstPropMode::OnlyInsideOwnBlock
-            );
-            Self::remove_const(&mut self.ecx, local);
+            debug_assert_eq!(self.can_const_prop[local], ConstPropMode::OnlyInsideOwnBlock);
+            self.remove_const(local);
         }
-        self.ecx.machine.written_only_inside_own_block_locals =
-            written_only_inside_own_block_locals;
+        self.written_only_inside_own_block_locals = written_only_inside_own_block_locals;
 
         if cfg!(debug_assertions) {
-            for (local, &mode) in self.ecx.machine.can_const_prop.iter_enumerated() {
+            for (local, &mode) in self.can_const_prop.iter_enumerated() {
                 match mode {
                     ConstPropMode::FullConstProp => {}
                     ConstPropMode::NoPropagation | ConstPropMode::OnlyInsideOwnBlock => {
diff --git a/compiler/rustc_mir_transform/src/coverage/mod.rs b/compiler/rustc_mir_transform/src/coverage/mod.rs
index a11d224e8f1..ad5fcc3acf1 100644
--- a/compiler/rustc_mir_transform/src/coverage/mod.rs
+++ b/compiler/rustc_mir_transform/src/coverage/mod.rs
@@ -59,167 +59,154 @@ impl<'tcx> MirPass<'tcx> for InstrumentCoverage {
             _ => {}
         }
 
-        trace!("InstrumentCoverage starting for {def_id:?}");
-        Instrumentor::new(tcx, mir_body).inject_counters();
-        trace!("InstrumentCoverage done for {def_id:?}");
+        instrument_function_for_coverage(tcx, mir_body);
     }
 }
 
-struct Instrumentor<'a, 'tcx> {
-    tcx: TyCtxt<'tcx>,
-    mir_body: &'a mut mir::Body<'tcx>,
-    hir_info: ExtractedHirInfo,
-    basic_coverage_blocks: CoverageGraph,
-}
-
-impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
-    fn new(tcx: TyCtxt<'tcx>, mir_body: &'a mut mir::Body<'tcx>) -> Self {
-        let hir_info = extract_hir_info(tcx, mir_body.source.def_id().expect_local());
+fn instrument_function_for_coverage<'tcx>(tcx: TyCtxt<'tcx>, mir_body: &mut mir::Body<'tcx>) {
+    let def_id = mir_body.source.def_id();
+    let _span = debug_span!("instrument_function_for_coverage", ?def_id).entered();
 
-        debug!(?hir_info, "instrumenting {:?}", mir_body.source.def_id());
+    let hir_info = extract_hir_info(tcx, def_id.expect_local());
+    let basic_coverage_blocks = CoverageGraph::from_mir(mir_body);
 
-        let basic_coverage_blocks = CoverageGraph::from_mir(mir_body);
+    ////////////////////////////////////////////////////
+    // Compute coverage spans from the `CoverageGraph`.
+    let Some(coverage_spans) =
+        spans::generate_coverage_spans(mir_body, &hir_info, &basic_coverage_blocks)
+    else {
+        // No relevant spans were found in MIR, so skip instrumenting this function.
+        return;
+    };
 
-        Self { tcx, mir_body, hir_info, basic_coverage_blocks }
+    ////////////////////////////////////////////////////
+    // Create an optimized mix of `Counter`s and `Expression`s for the `CoverageGraph`. Ensure
+    // every coverage span has a `Counter` or `Expression` assigned to its `BasicCoverageBlock`
+    // and all `Expression` dependencies (operands) are also generated, for any other
+    // `BasicCoverageBlock`s not already associated with a coverage span.
+    let bcb_has_coverage_spans = |bcb| coverage_spans.bcb_has_coverage_spans(bcb);
+    let coverage_counters =
+        CoverageCounters::make_bcb_counters(&basic_coverage_blocks, bcb_has_coverage_spans);
+
+    let mappings = create_mappings(tcx, &hir_info, &coverage_spans, &coverage_counters);
+    if mappings.is_empty() {
+        // No spans could be converted into valid mappings, so skip this function.
+        debug!("no spans could be converted into valid mappings; skipping");
+        return;
     }
 
-    fn inject_counters(&'a mut self) {
-        ////////////////////////////////////////////////////
-        // Compute coverage spans from the `CoverageGraph`.
-        let Some(coverage_spans) = CoverageSpans::generate_coverage_spans(
-            self.mir_body,
-            &self.hir_info,
-            &self.basic_coverage_blocks,
-        ) else {
-            // No relevant spans were found in MIR, so skip instrumenting this function.
-            return;
-        };
-
-        ////////////////////////////////////////////////////
-        // Create an optimized mix of `Counter`s and `Expression`s for the `CoverageGraph`. Ensure
-        // every coverage span has a `Counter` or `Expression` assigned to its `BasicCoverageBlock`
-        // and all `Expression` dependencies (operands) are also generated, for any other
-        // `BasicCoverageBlock`s not already associated with a coverage span.
-        let bcb_has_coverage_spans = |bcb| coverage_spans.bcb_has_coverage_spans(bcb);
-        let coverage_counters = CoverageCounters::make_bcb_counters(
-            &self.basic_coverage_blocks,
-            bcb_has_coverage_spans,
-        );
+    inject_coverage_statements(
+        mir_body,
+        &basic_coverage_blocks,
+        bcb_has_coverage_spans,
+        &coverage_counters,
+    );
 
-        let mappings = self.create_mappings(&coverage_spans, &coverage_counters);
-        if mappings.is_empty() {
-            // No spans could be converted into valid mappings, so skip this function.
-            debug!("no spans could be converted into valid mappings; skipping");
-            return;
-        }
+    mir_body.function_coverage_info = Some(Box::new(FunctionCoverageInfo {
+        function_source_hash: hir_info.function_source_hash,
+        num_counters: coverage_counters.num_counters(),
+        expressions: coverage_counters.into_expressions(),
+        mappings,
+    }));
+}
 
-        self.inject_coverage_statements(bcb_has_coverage_spans, &coverage_counters);
+/// For each coverage span extracted from MIR, create a corresponding
+/// mapping.
+///
+/// Precondition: All BCBs corresponding to those spans have been given
+/// coverage counters.
+fn create_mappings<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    hir_info: &ExtractedHirInfo,
+    coverage_spans: &CoverageSpans,
+    coverage_counters: &CoverageCounters,
+) -> Vec<Mapping> {
+    let source_map = tcx.sess.source_map();
+    let body_span = hir_info.body_span;
+
+    let source_file = source_map.lookup_source_file(body_span.lo());
+    use rustc_session::RemapFileNameExt;
+    let file_name = Symbol::intern(&source_file.name.for_codegen(tcx.sess).to_string_lossy());
+
+    let term_for_bcb = |bcb| {
+        coverage_counters
+            .bcb_counter(bcb)
+            .expect("all BCBs with spans were given counters")
+            .as_term()
+    };
 
-        self.mir_body.function_coverage_info = Some(Box::new(FunctionCoverageInfo {
-            function_source_hash: self.hir_info.function_source_hash,
-            num_counters: coverage_counters.num_counters(),
-            expressions: coverage_counters.into_expressions(),
-            mappings,
-        }));
-    }
+    coverage_spans
+        .all_bcb_mappings()
+        .filter_map(|&BcbMapping { kind: bcb_mapping_kind, span }| {
+            let kind = match bcb_mapping_kind {
+                BcbMappingKind::Code(bcb) => MappingKind::Code(term_for_bcb(bcb)),
+            };
+            let code_region = make_code_region(source_map, file_name, span, body_span)?;
+            Some(Mapping { kind, code_region })
+        })
+        .collect::<Vec<_>>()
+}
 
-    /// For each coverage span extracted from MIR, create a corresponding
-    /// mapping.
-    ///
-    /// Precondition: All BCBs corresponding to those spans have been given
-    /// coverage counters.
-    fn create_mappings(
-        &self,
-        coverage_spans: &CoverageSpans,
-        coverage_counters: &CoverageCounters,
-    ) -> Vec<Mapping> {
-        let source_map = self.tcx.sess.source_map();
-        let body_span = self.hir_info.body_span;
-
-        let source_file = source_map.lookup_source_file(body_span.lo());
-        use rustc_session::RemapFileNameExt;
-        let file_name =
-            Symbol::intern(&source_file.name.for_codegen(self.tcx.sess).to_string_lossy());
-
-        let term_for_bcb = |bcb| {
-            coverage_counters
-                .bcb_counter(bcb)
-                .expect("all BCBs with spans were given counters")
-                .as_term()
+/// For each BCB node or BCB edge that has an associated coverage counter,
+/// inject any necessary coverage statements into MIR.
+fn inject_coverage_statements<'tcx>(
+    mir_body: &mut mir::Body<'tcx>,
+    basic_coverage_blocks: &CoverageGraph,
+    bcb_has_coverage_spans: impl Fn(BasicCoverageBlock) -> bool,
+    coverage_counters: &CoverageCounters,
+) {
+    // Process the counters associated with BCB nodes.
+    for (bcb, counter_kind) in coverage_counters.bcb_node_counters() {
+        let do_inject = match counter_kind {
+            // Counter-increment statements always need to be injected.
+            BcbCounter::Counter { .. } => true,
+            // The only purpose of expression-used statements is to detect
+            // when a mapping is unreachable, so we only inject them for
+            // expressions with one or more mappings.
+            BcbCounter::Expression { .. } => bcb_has_coverage_spans(bcb),
         };
-
-        coverage_spans
-            .all_bcb_mappings()
-            .filter_map(|&BcbMapping { kind: bcb_mapping_kind, span }| {
-                let kind = match bcb_mapping_kind {
-                    BcbMappingKind::Code(bcb) => MappingKind::Code(term_for_bcb(bcb)),
-                };
-                let code_region = make_code_region(source_map, file_name, span, body_span)?;
-                Some(Mapping { kind, code_region })
-            })
-            .collect::<Vec<_>>()
+        if do_inject {
+            inject_statement(
+                mir_body,
+                make_mir_coverage_kind(counter_kind),
+                basic_coverage_blocks[bcb].leader_bb(),
+            );
+        }
     }
 
-    /// For each BCB node or BCB edge that has an associated coverage counter,
-    /// inject any necessary coverage statements into MIR.
-    fn inject_coverage_statements(
-        &mut self,
-        bcb_has_coverage_spans: impl Fn(BasicCoverageBlock) -> bool,
-        coverage_counters: &CoverageCounters,
-    ) {
-        // Process the counters associated with BCB nodes.
-        for (bcb, counter_kind) in coverage_counters.bcb_node_counters() {
-            let do_inject = match counter_kind {
-                // Counter-increment statements always need to be injected.
-                BcbCounter::Counter { .. } => true,
-                // The only purpose of expression-used statements is to detect
-                // when a mapping is unreachable, so we only inject them for
-                // expressions with one or more mappings.
-                BcbCounter::Expression { .. } => bcb_has_coverage_spans(bcb),
-            };
-            if do_inject {
-                inject_statement(
-                    self.mir_body,
-                    self.make_mir_coverage_kind(counter_kind),
-                    self.basic_coverage_blocks[bcb].leader_bb(),
-                );
-            }
+    // Process the counters associated with BCB edges.
+    for (from_bcb, to_bcb, counter_kind) in coverage_counters.bcb_edge_counters() {
+        let do_inject = match counter_kind {
+            // Counter-increment statements always need to be injected.
+            BcbCounter::Counter { .. } => true,
+            // BCB-edge expressions never have mappings, so they never need
+            // a corresponding statement.
+            BcbCounter::Expression { .. } => false,
+        };
+        if !do_inject {
+            continue;
         }
 
-        // Process the counters associated with BCB edges.
-        for (from_bcb, to_bcb, counter_kind) in coverage_counters.bcb_edge_counters() {
-            let do_inject = match counter_kind {
-                // Counter-increment statements always need to be injected.
-                BcbCounter::Counter { .. } => true,
-                // BCB-edge expressions never have mappings, so they never need
-                // a corresponding statement.
-                BcbCounter::Expression { .. } => false,
-            };
-            if !do_inject {
-                continue;
-            }
-
-            // We need to inject a coverage statement into a new BB between the
-            // last BB of `from_bcb` and the first BB of `to_bcb`.
-            let from_bb = self.basic_coverage_blocks[from_bcb].last_bb();
-            let to_bb = self.basic_coverage_blocks[to_bcb].leader_bb();
+        // We need to inject a coverage statement into a new BB between the
+        // last BB of `from_bcb` and the first BB of `to_bcb`.
+        let from_bb = basic_coverage_blocks[from_bcb].last_bb();
+        let to_bb = basic_coverage_blocks[to_bcb].leader_bb();
 
-            let new_bb = inject_edge_counter_basic_block(self.mir_body, from_bb, to_bb);
-            debug!(
-                "Edge {from_bcb:?} (last {from_bb:?}) -> {to_bcb:?} (leader {to_bb:?}) \
+        let new_bb = inject_edge_counter_basic_block(mir_body, from_bb, to_bb);
+        debug!(
+            "Edge {from_bcb:?} (last {from_bb:?}) -> {to_bcb:?} (leader {to_bb:?}) \
                 requires a new MIR BasicBlock {new_bb:?} for edge counter {counter_kind:?}",
-            );
+        );
 
-            // Inject a counter into the newly-created BB.
-            inject_statement(self.mir_body, self.make_mir_coverage_kind(counter_kind), new_bb);
-        }
+        // Inject a counter into the newly-created BB.
+        inject_statement(mir_body, make_mir_coverage_kind(counter_kind), new_bb);
     }
+}
 
-    fn make_mir_coverage_kind(&self, counter_kind: &BcbCounter) -> CoverageKind {
-        match *counter_kind {
-            BcbCounter::Counter { id } => CoverageKind::CounterIncrement { id },
-            BcbCounter::Expression { id } => CoverageKind::ExpressionUsed { id },
-        }
+fn make_mir_coverage_kind(counter_kind: &BcbCounter) -> CoverageKind {
+    match *counter_kind {
+        BcbCounter::Counter { id } => CoverageKind::CounterIncrement { id },
+        BcbCounter::Expression { id } => CoverageKind::ExpressionUsed { id },
     }
 }
 
@@ -329,7 +316,7 @@ fn make_code_region(
     start_line = source_map.doctest_offset_line(&file.name, start_line);
     end_line = source_map.doctest_offset_line(&file.name, end_line);
 
-    Some(CodeRegion {
+    check_code_region(CodeRegion {
         file_name,
         start_line: start_line as u32,
         start_col: start_col as u32,
@@ -338,6 +325,39 @@ fn make_code_region(
     })
 }
 
+/// If `llvm-cov` sees a code region that is improperly ordered (end < start),
+/// it will immediately exit with a fatal error. To prevent that from happening,
+/// discard regions that are improperly ordered, or might be interpreted in a
+/// way that makes them improperly ordered.
+fn check_code_region(code_region: CodeRegion) -> Option<CodeRegion> {
+    let CodeRegion { file_name: _, start_line, start_col, end_line, end_col } = code_region;
+
+    // Line/column coordinates are supposed to be 1-based. If we ever emit
+    // coordinates of 0, `llvm-cov` might misinterpret them.
+    let all_nonzero = [start_line, start_col, end_line, end_col].into_iter().all(|x| x != 0);
+    // Coverage mappings use the high bit of `end_col` to indicate that a
+    // region is actually a "gap" region, so make sure it's unset.
+    let end_col_has_high_bit_unset = (end_col & (1 << 31)) == 0;
+    // If a region is improperly ordered (end < start), `llvm-cov` will exit
+    // with a fatal error, which is inconvenient for users and hard to debug.
+    let is_ordered = (start_line, start_col) <= (end_line, end_col);
+
+    if all_nonzero && end_col_has_high_bit_unset && is_ordered {
+        Some(code_region)
+    } else {
+        debug!(
+            ?code_region,
+            ?all_nonzero,
+            ?end_col_has_high_bit_unset,
+            ?is_ordered,
+            "Skipping code region that would be misinterpreted or rejected by LLVM"
+        );
+        // If this happens in a debug build, ICE to make it easier to notice.
+        debug_assert!(false, "Improper code region: {code_region:?}");
+        None
+    }
+}
+
 fn is_eligible_for_coverage(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
     // Only instrument functions, methods, and closures (not constants since they are evaluated
     // at compile time by Miri).
@@ -351,7 +371,18 @@ fn is_eligible_for_coverage(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
         return false;
     }
 
+    // Don't instrument functions with `#[automatically_derived]` on their
+    // enclosing impl block, on the assumption that most users won't care about
+    // coverage for derived impls.
+    if let Some(impl_of) = tcx.impl_of_method(def_id.to_def_id())
+        && tcx.is_automatically_derived(impl_of)
+    {
+        trace!("InstrumentCoverage skipped for {def_id:?} (automatically derived)");
+        return false;
+    }
+
     if tcx.codegen_fn_attrs(def_id).flags.contains(CodegenFnAttrFlags::NO_COVERAGE) {
+        trace!("InstrumentCoverage skipped for {def_id:?} (`#[coverage(off)]`)");
         return false;
     }
 
diff --git a/compiler/rustc_mir_transform/src/coverage/spans.rs b/compiler/rustc_mir_transform/src/coverage/spans.rs
index 81f6c831206..dee6a3b7143 100644
--- a/compiler/rustc_mir_transform/src/coverage/spans.rs
+++ b/compiler/rustc_mir_transform/src/coverage/spans.rs
@@ -26,45 +26,6 @@ pub(super) struct CoverageSpans {
 }
 
 impl CoverageSpans {
-    /// Extracts coverage-relevant spans from MIR, and associates them with
-    /// their corresponding BCBs.
-    ///
-    /// Returns `None` if no coverage-relevant spans could be extracted.
-    pub(super) fn generate_coverage_spans(
-        mir_body: &mir::Body<'_>,
-        hir_info: &ExtractedHirInfo,
-        basic_coverage_blocks: &CoverageGraph,
-    ) -> Option<Self> {
-        let mut mappings = vec![];
-
-        let coverage_spans = CoverageSpansGenerator::generate_coverage_spans(
-            mir_body,
-            hir_info,
-            basic_coverage_blocks,
-        );
-        mappings.extend(coverage_spans.into_iter().map(|CoverageSpan { bcb, span, .. }| {
-            // Each span produced by the generator represents an ordinary code region.
-            BcbMapping { kind: BcbMappingKind::Code(bcb), span }
-        }));
-
-        if mappings.is_empty() {
-            return None;
-        }
-
-        // Identify which BCBs have one or more mappings.
-        let mut bcb_has_mappings = BitSet::new_empty(basic_coverage_blocks.num_nodes());
-        let mut insert = |bcb| {
-            bcb_has_mappings.insert(bcb);
-        };
-        for &BcbMapping { kind, span: _ } in &mappings {
-            match kind {
-                BcbMappingKind::Code(bcb) => insert(bcb),
-            }
-        }
-
-        Some(Self { bcb_has_mappings, mappings })
-    }
-
     pub(super) fn bcb_has_coverage_spans(&self, bcb: BasicCoverageBlock) -> bool {
         self.bcb_has_mappings.contains(bcb)
     }
@@ -74,6 +35,43 @@ impl CoverageSpans {
     }
 }
 
+/// Extracts coverage-relevant spans from MIR, and associates them with
+/// their corresponding BCBs.
+///
+/// Returns `None` if no coverage-relevant spans could be extracted.
+pub(super) fn generate_coverage_spans(
+    mir_body: &mir::Body<'_>,
+    hir_info: &ExtractedHirInfo,
+    basic_coverage_blocks: &CoverageGraph,
+) -> Option<CoverageSpans> {
+    let mut mappings = vec![];
+
+    let sorted_spans =
+        from_mir::mir_to_initial_sorted_coverage_spans(mir_body, hir_info, basic_coverage_blocks);
+    let coverage_spans = SpansRefiner::refine_sorted_spans(basic_coverage_blocks, sorted_spans);
+    mappings.extend(coverage_spans.into_iter().map(|CoverageSpan { bcb, span, .. }| {
+        // Each span produced by the generator represents an ordinary code region.
+        BcbMapping { kind: BcbMappingKind::Code(bcb), span }
+    }));
+
+    if mappings.is_empty() {
+        return None;
+    }
+
+    // Identify which BCBs have one or more mappings.
+    let mut bcb_has_mappings = BitSet::new_empty(basic_coverage_blocks.num_nodes());
+    let mut insert = |bcb| {
+        bcb_has_mappings.insert(bcb);
+    };
+    for &BcbMapping { kind, span: _ } in &mappings {
+        match kind {
+            BcbMappingKind::Code(bcb) => insert(bcb),
+        }
+    }
+
+    Some(CoverageSpans { bcb_has_mappings, mappings })
+}
+
 /// A BCB is deconstructed into one or more `Span`s. Each `Span` maps to a `CoverageSpan` that
 /// references the originating BCB and one or more MIR `Statement`s and/or `Terminator`s.
 /// Initially, the `Span`s come from the `Statement`s and `Terminator`s, but subsequent
@@ -130,7 +128,7 @@ impl CoverageSpan {
 ///  * Merge spans that represent continuous (both in source code and control flow), non-branching
 ///    execution
 ///  * Carve out (leave uncovered) any span that will be counted by another MIR (notably, closures)
-struct CoverageSpansGenerator<'a> {
+struct SpansRefiner<'a> {
     /// The BasicCoverageBlock Control Flow Graph (BCB CFG).
     basic_coverage_blocks: &'a CoverageGraph,
 
@@ -173,40 +171,15 @@ struct CoverageSpansGenerator<'a> {
     refined_spans: Vec<CoverageSpan>,
 }
 
-impl<'a> CoverageSpansGenerator<'a> {
-    /// Generate a minimal set of `CoverageSpan`s, each representing a contiguous code region to be
-    /// counted.
-    ///
-    /// The basic steps are:
-    ///
-    /// 1. Extract an initial set of spans from the `Statement`s and `Terminator`s of each
-    ///    `BasicCoverageBlockData`.
-    /// 2. Sort the spans by span.lo() (starting position). Spans that start at the same position
-    ///    are sorted with longer spans before shorter spans; and equal spans are sorted
-    ///    (deterministically) based on "dominator" relationship (if any).
-    /// 3. Traverse the spans in sorted order to identify spans that can be dropped (for instance,
-    ///    if another span or spans are already counting the same code region), or should be merged
-    ///    into a broader combined span (because it represents a contiguous, non-branching, and
-    ///    uninterrupted region of source code).
-    ///
-    ///    Closures are exposed in their enclosing functions as `Assign` `Rvalue`s, and since
-    ///    closures have their own MIR, their `Span` in their enclosing function should be left
-    ///    "uncovered".
-    ///
-    /// Note the resulting vector of `CoverageSpan`s may not be fully sorted (and does not need
-    /// to be).
-    pub(super) fn generate_coverage_spans(
-        mir_body: &mir::Body<'_>,
-        hir_info: &ExtractedHirInfo,
+impl<'a> SpansRefiner<'a> {
+    /// Takes the initial list of (sorted) spans extracted from MIR, and "refines"
+    /// them by merging compatible adjacent spans, removing redundant spans,
+    /// and carving holes in spans when they overlap in unwanted ways.
+    fn refine_sorted_spans(
         basic_coverage_blocks: &'a CoverageGraph,
+        sorted_spans: Vec<CoverageSpan>,
     ) -> Vec<CoverageSpan> {
-        let sorted_spans = from_mir::mir_to_initial_sorted_coverage_spans(
-            mir_body,
-            hir_info,
-            basic_coverage_blocks,
-        );
-
-        let coverage_spans = Self {
+        let this = Self {
             basic_coverage_blocks,
             sorted_spans_iter: sorted_spans.into_iter(),
             some_curr: None,
@@ -217,7 +190,7 @@ impl<'a> CoverageSpansGenerator<'a> {
             refined_spans: Vec::with_capacity(basic_coverage_blocks.num_nodes() * 2),
         };
 
-        coverage_spans.to_refined_spans()
+        this.to_refined_spans()
     }
 
     /// Iterate through the sorted `CoverageSpan`s, and return the refined list of merged and
diff --git a/compiler/rustc_mir_transform/src/coverage/spans/from_mir.rs b/compiler/rustc_mir_transform/src/coverage/spans/from_mir.rs
index 1b6dfccd574..8d8e8e61327 100644
--- a/compiler/rustc_mir_transform/src/coverage/spans/from_mir.rs
+++ b/compiler/rustc_mir_transform/src/coverage/spans/from_mir.rs
@@ -12,6 +12,12 @@ use crate::coverage::graph::{
 use crate::coverage::spans::CoverageSpan;
 use crate::coverage::ExtractedHirInfo;
 
+/// Traverses the MIR body to produce an initial collection of coverage-relevant
+/// spans, each associated with a node in the coverage graph (BCB) and possibly
+/// other metadata.
+///
+/// The returned spans are sorted in a specific order that is expected by the
+/// subsequent span-refinement step.
 pub(super) fn mir_to_initial_sorted_coverage_spans(
     mir_body: &mir::Body<'_>,
     hir_info: &ExtractedHirInfo,
diff --git a/compiler/rustc_mir_transform/src/dataflow_const_prop.rs b/compiler/rustc_mir_transform/src/dataflow_const_prop.rs
index ad12bce9b02..d5f22b2cdbc 100644
--- a/compiler/rustc_mir_transform/src/dataflow_const_prop.rs
+++ b/compiler/rustc_mir_transform/src/dataflow_const_prop.rs
@@ -403,7 +403,12 @@ impl<'a, 'tcx> ConstAnalysis<'a, 'tcx> {
             operand,
             &mut |elem, op| match elem {
                 TrackElem::Field(idx) => self.ecx.project_field(op, idx.as_usize()).ok(),
-                TrackElem::Variant(idx) => self.ecx.project_downcast(op, idx).ok(),
+                TrackElem::Variant(idx) => {
+                    if op.layout.for_variant(&self.ecx, idx).abi.is_uninhabited() {
+                        return None;
+                    }
+                    self.ecx.project_downcast(op, idx).ok()
+                }
                 TrackElem::Discriminant => {
                     let variant = self.ecx.read_discriminant(op).ok()?;
                     let discr_value =
diff --git a/compiler/rustc_mir_transform/src/errors.rs b/compiler/rustc_mir_transform/src/errors.rs
index 2ee660ddc9b..4574cb4d28d 100644
--- a/compiler/rustc_mir_transform/src/errors.rs
+++ b/compiler/rustc_mir_transform/src/errors.rs
@@ -201,45 +201,39 @@ impl<'a> DecorateLint<'a, ()> for UnsafeOpInUnsafeFn {
     }
 }
 
-pub(crate) enum AssertLint<P> {
-    ArithmeticOverflow(Span, AssertKind<P>),
-    UnconditionalPanic(Span, AssertKind<P>),
+pub(crate) struct AssertLint<P> {
+    pub span: Span,
+    pub assert_kind: AssertKind<P>,
+    pub lint_kind: AssertLintKind,
+}
+
+pub(crate) enum AssertLintKind {
+    ArithmeticOverflow,
+    UnconditionalPanic,
 }
 
 impl<'a, P: std::fmt::Debug> DecorateLint<'a, ()> for AssertLint<P> {
     fn decorate_lint<'b>(self, diag: &'b mut DiagnosticBuilder<'a, ()>) {
-        let span = self.span();
-        let assert_kind = self.panic();
-        let message = assert_kind.diagnostic_message();
-        assert_kind.add_args(&mut |name, value| {
+        let message = self.assert_kind.diagnostic_message();
+        self.assert_kind.add_args(&mut |name, value| {
             diag.arg(name, value);
         });
-        diag.span_label(span, message);
+        diag.span_label(self.span, message);
     }
 
     fn msg(&self) -> DiagnosticMessage {
-        match self {
-            AssertLint::ArithmeticOverflow(..) => fluent::mir_transform_arithmetic_overflow,
-            AssertLint::UnconditionalPanic(..) => fluent::mir_transform_operation_will_panic,
+        match self.lint_kind {
+            AssertLintKind::ArithmeticOverflow => fluent::mir_transform_arithmetic_overflow,
+            AssertLintKind::UnconditionalPanic => fluent::mir_transform_operation_will_panic,
         }
     }
 }
 
-impl<P> AssertLint<P> {
+impl AssertLintKind {
     pub fn lint(&self) -> &'static Lint {
         match self {
-            AssertLint::ArithmeticOverflow(..) => lint::builtin::ARITHMETIC_OVERFLOW,
-            AssertLint::UnconditionalPanic(..) => lint::builtin::UNCONDITIONAL_PANIC,
-        }
-    }
-    pub fn span(&self) -> Span {
-        match self {
-            AssertLint::ArithmeticOverflow(sp, _) | AssertLint::UnconditionalPanic(sp, _) => *sp,
-        }
-    }
-    pub fn panic(self) -> AssertKind<P> {
-        match self {
-            AssertLint::ArithmeticOverflow(_, p) | AssertLint::UnconditionalPanic(_, p) => p,
+            AssertLintKind::ArithmeticOverflow => lint::builtin::ARITHMETIC_OVERFLOW,
+            AssertLintKind::UnconditionalPanic => lint::builtin::UNCONDITIONAL_PANIC,
         }
     }
 }
diff --git a/compiler/rustc_monomorphize/src/collector.rs b/compiler/rustc_monomorphize/src/collector.rs
index 8b991268819..b86244e5a4b 100644
--- a/compiler/rustc_monomorphize/src/collector.rs
+++ b/compiler/rustc_monomorphize/src/collector.rs
@@ -1113,7 +1113,13 @@ fn find_vtable_types_for_unsizing<'tcx>(
             assert_eq!(source_adt_def, target_adt_def);
 
             let CustomCoerceUnsized::Struct(coerce_index) =
-                crate::custom_coerce_unsize_info(tcx, source_ty, target_ty);
+                match crate::custom_coerce_unsize_info(tcx, source_ty, target_ty) {
+                    Ok(ccu) => ccu,
+                    Err(e) => {
+                        let e = Ty::new_error(tcx.tcx, e);
+                        return (e, e);
+                    }
+                };
 
             let source_fields = &source_adt_def.non_enum_variant().fields;
             let target_fields = &target_adt_def.non_enum_variant().fields;
diff --git a/compiler/rustc_monomorphize/src/lib.rs b/compiler/rustc_monomorphize/src/lib.rs
index 2f5f2d15cd4..3fa40db3c80 100644
--- a/compiler/rustc_monomorphize/src/lib.rs
+++ b/compiler/rustc_monomorphize/src/lib.rs
@@ -15,6 +15,7 @@ use rustc_middle::query::{Providers, TyCtxtAt};
 use rustc_middle::traits;
 use rustc_middle::ty::adjustment::CustomCoerceUnsized;
 use rustc_middle::ty::{self, Ty};
+use rustc_span::ErrorGuaranteed;
 
 mod collector;
 mod errors;
@@ -28,7 +29,7 @@ fn custom_coerce_unsize_info<'tcx>(
     tcx: TyCtxtAt<'tcx>,
     source_ty: Ty<'tcx>,
     target_ty: Ty<'tcx>,
-) -> CustomCoerceUnsized {
+) -> Result<CustomCoerceUnsized, ErrorGuaranteed> {
     let trait_ref = ty::TraitRef::from_lang_item(
         tcx.tcx,
         LangItem::CoerceUnsized,
@@ -40,7 +41,7 @@ fn custom_coerce_unsize_info<'tcx>(
         Ok(traits::ImplSource::UserDefined(traits::ImplSourceUserDefinedData {
             impl_def_id,
             ..
-        })) => tcx.coerce_unsized_info(impl_def_id).custom_kind.unwrap(),
+        })) => Ok(tcx.coerce_unsized_info(impl_def_id)?.custom_kind.unwrap()),
         impl_source => {
             bug!("invalid `CoerceUnsized` impl_source: {:?}", impl_source);
         }
diff --git a/compiler/rustc_privacy/src/lib.rs b/compiler/rustc_privacy/src/lib.rs
index 0d4ee1e8dca..ae10695fae4 100644
--- a/compiler/rustc_privacy/src/lib.rs
+++ b/compiler/rustc_privacy/src/lib.rs
@@ -24,13 +24,13 @@ use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{DefId, LocalDefId, LocalModDefId, CRATE_DEF_ID};
 use rustc_hir::intravisit::{self, Visitor};
 use rustc_hir::{AssocItemKind, ForeignItemKind, ItemId, PatKind};
-use rustc_middle::bug;
 use rustc_middle::hir::nested_filter;
 use rustc_middle::middle::privacy::{EffectiveVisibilities, EffectiveVisibility, Level};
 use rustc_middle::query::Providers;
 use rustc_middle::ty::GenericArgs;
 use rustc_middle::ty::{self, Const, GenericParamDefKind};
 use rustc_middle::ty::{TraitRef, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitor};
+use rustc_middle::{bug, span_bug};
 use rustc_session::lint;
 use rustc_span::hygiene::Transparency;
 use rustc_span::symbol::{kw, sym, Ident};
@@ -1064,29 +1064,22 @@ impl<'tcx> Visitor<'tcx> for NamePrivacyVisitor<'tcx> {
 
 struct TypePrivacyVisitor<'tcx> {
     tcx: TyCtxt<'tcx>,
+    module_def_id: LocalModDefId,
     maybe_typeck_results: Option<&'tcx ty::TypeckResults<'tcx>>,
-    current_item: LocalDefId,
     span: Span,
 }
 
 impl<'tcx> TypePrivacyVisitor<'tcx> {
-    /// Gets the type-checking results for the current body.
-    /// As this will ICE if called outside bodies, only call when working with
-    /// `Expr` or `Pat` nodes (they are guaranteed to be found only in bodies).
-    #[track_caller]
-    fn typeck_results(&self) -> &'tcx ty::TypeckResults<'tcx> {
-        self.maybe_typeck_results
-            .expect("`TypePrivacyVisitor::typeck_results` called outside of body")
-    }
-
     fn item_is_accessible(&self, did: DefId) -> bool {
-        self.tcx.visibility(did).is_accessible_from(self.current_item, self.tcx)
+        self.tcx.visibility(did).is_accessible_from(self.module_def_id, self.tcx)
     }
 
     // Take node-id of an expression or pattern and check its type for privacy.
     fn check_expr_pat_type(&mut self, id: hir::HirId, span: Span) -> bool {
         self.span = span;
-        let typeck_results = self.typeck_results();
+        let typeck_results = self
+            .maybe_typeck_results
+            .unwrap_or_else(|| span_bug!(span, "`hir::Expr` or `hir::Pat` outside of a body"));
         let result: ControlFlow<()> = try {
             self.visit(typeck_results.node_type(id))?;
             self.visit(typeck_results.node_args(id))?;
@@ -1107,35 +1100,13 @@ impl<'tcx> TypePrivacyVisitor<'tcx> {
 }
 
 impl<'tcx> Visitor<'tcx> for TypePrivacyVisitor<'tcx> {
-    type NestedFilter = nested_filter::All;
-
-    /// We want to visit items in the context of their containing
-    /// module and so forth, so supply a crate for doing a deep walk.
-    fn nested_visit_map(&mut self) -> Self::Map {
-        self.tcx.hir()
-    }
-
-    fn visit_mod(&mut self, _m: &'tcx hir::Mod<'tcx>, _s: Span, _n: hir::HirId) {
-        // Don't visit nested modules, since we run a separate visitor walk
-        // for each module in `effective_visibilities`
-    }
-
-    fn visit_nested_body(&mut self, body: hir::BodyId) {
+    fn visit_nested_body(&mut self, body_id: hir::BodyId) {
         let old_maybe_typeck_results =
-            self.maybe_typeck_results.replace(self.tcx.typeck_body(body));
-        let body = self.tcx.hir().body(body);
-        self.visit_body(body);
+            self.maybe_typeck_results.replace(self.tcx.typeck_body(body_id));
+        self.visit_body(self.tcx.hir().body(body_id));
         self.maybe_typeck_results = old_maybe_typeck_results;
     }
 
-    fn visit_generic_arg(&mut self, generic_arg: &'tcx hir::GenericArg<'tcx>) {
-        match generic_arg {
-            hir::GenericArg::Type(t) => self.visit_ty(t),
-            hir::GenericArg::Infer(inf) => self.visit_infer(inf),
-            hir::GenericArg::Lifetime(_) | hir::GenericArg::Const(_) => {}
-        }
-    }
-
     fn visit_ty(&mut self, hir_ty: &'tcx hir::Ty<'tcx>) {
         self.span = hir_ty.span;
         if let Some(typeck_results) = self.maybe_typeck_results {
@@ -1163,19 +1134,19 @@ impl<'tcx> Visitor<'tcx> for TypePrivacyVisitor<'tcx> {
                     return;
                 }
             } else {
-                // We don't do anything for const infers here.
+                // FIXME: check types of const infers here.
             }
         } else {
-            bug!("visit_infer without typeck_results");
+            span_bug!(self.span, "`hir::InferArg` outside of a body");
         }
         intravisit::walk_inf(self, inf);
     }
 
     fn visit_trait_ref(&mut self, trait_ref: &'tcx hir::TraitRef<'tcx>) {
         self.span = trait_ref.path.span;
-        if self.maybe_typeck_results.is_none() {
-            // Avoid calling `hir_trait_to_predicates` in bodies, it will ICE.
-            // The traits' privacy in bodies is already checked as a part of trait object types.
+        if self.maybe_typeck_results.is_some() {
+            // Privacy of traits in bodies is checked as a part of trait object types.
+        } else {
             let bounds = rustc_hir_analysis::hir_trait_to_predicates(
                 self.tcx,
                 trait_ref,
@@ -1223,7 +1194,10 @@ impl<'tcx> Visitor<'tcx> for TypePrivacyVisitor<'tcx> {
             hir::ExprKind::MethodCall(segment, ..) => {
                 // Method calls have to be checked specially.
                 self.span = segment.ident.span;
-                if let Some(def_id) = self.typeck_results().type_dependent_def_id(expr.hir_id) {
+                let typeck_results = self
+                    .maybe_typeck_results
+                    .unwrap_or_else(|| span_bug!(self.span, "`hir::Expr` outside of a body"));
+                if let Some(def_id) = typeck_results.type_dependent_def_id(expr.hir_id) {
                     if self.visit(self.tcx.type_of(def_id).instantiate_identity()).is_break() {
                         return;
                     }
@@ -1251,9 +1225,13 @@ impl<'tcx> Visitor<'tcx> for TypePrivacyVisitor<'tcx> {
                 Res::Def(kind, def_id) => Some((kind, def_id)),
                 _ => None,
             },
-            hir::QPath::TypeRelative(..) | hir::QPath::LangItem(..) => self
-                .maybe_typeck_results
-                .and_then(|typeck_results| typeck_results.type_dependent_def(id)),
+            hir::QPath::TypeRelative(..) | hir::QPath::LangItem(..) => {
+                match self.maybe_typeck_results {
+                    Some(typeck_results) => typeck_results.type_dependent_def(id),
+                    // FIXME: Check type-relative associated types in signatures.
+                    None => None,
+                }
+            }
         };
         let def = def.filter(|(kind, _)| {
             matches!(
@@ -1307,15 +1285,6 @@ impl<'tcx> Visitor<'tcx> for TypePrivacyVisitor<'tcx> {
 
         intravisit::walk_local(self, local);
     }
-
-    // Check types in item interfaces.
-    fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
-        let orig_current_item = mem::replace(&mut self.current_item, item.owner_id.def_id);
-        let old_maybe_typeck_results = self.maybe_typeck_results.take();
-        intravisit::walk_item(self, item);
-        self.maybe_typeck_results = old_maybe_typeck_results;
-        self.current_item = orig_current_item;
-    }
 }
 
 impl<'tcx> DefIdVisitor<'tcx> for TypePrivacyVisitor<'tcx> {
@@ -1785,13 +1754,8 @@ fn check_mod_privacy(tcx: TyCtxt<'_>, module_def_id: LocalModDefId) {
 
     // Check privacy of explicitly written types and traits as well as
     // inferred types of expressions and patterns.
-    let mut visitor = TypePrivacyVisitor {
-        tcx,
-        maybe_typeck_results: None,
-        current_item: module_def_id.to_local_def_id(),
-        span,
-    };
-    intravisit::walk_mod(&mut visitor, module, hir_id);
+    let mut visitor = TypePrivacyVisitor { tcx, module_def_id, maybe_typeck_results: None, span };
+    tcx.hir().visit_item_likes_in_module(module_def_id, &mut visitor);
 }
 
 fn effective_visibilities(tcx: TyCtxt<'_>, (): ()) -> &EffectiveVisibilities {
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index 24aa336c68f..891a83ce80c 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -332,20 +332,6 @@ impl Session {
         }
     }
 
-    // FIXME(matthewjasper) Remove this method, it should never be needed.
-    pub fn track_errors<F, T>(&self, f: F) -> Result<T, ErrorGuaranteed>
-    where
-        F: FnOnce() -> T,
-    {
-        let old_count = self.dcx().err_count();
-        let result = f();
-        if self.dcx().err_count() == old_count {
-            Ok(result)
-        } else {
-            Err(self.dcx().delayed_bug("`self.err_count()` changed but an error was not emitted"))
-        }
-    }
-
     /// Used for code paths of expensive computations that should only take place when
     /// warnings or errors are emitted. If no messages are emitted ("good path"), then
     /// it's likely a bug.
@@ -1524,16 +1510,25 @@ pub trait RemapFileNameExt {
     where
         Self: 'a;
 
-    fn for_scope(&self, sess: &Session, scopes: RemapPathScopeComponents) -> Self::Output<'_>;
+    /// Returns a possibly remapped filename based on the passed scope and remap cli options.
+    ///
+    /// One and only one scope should be passed to this method. For anything related to
+    /// "codegen" see the [`RemapFileNameExt::for_codegen`] method.
+    fn for_scope(&self, sess: &Session, scope: RemapPathScopeComponents) -> Self::Output<'_>;
 
+    /// Return a possibly remapped filename, to be used in "codegen" related parts.
     fn for_codegen(&self, sess: &Session) -> Self::Output<'_>;
 }
 
 impl RemapFileNameExt for rustc_span::FileName {
     type Output<'a> = rustc_span::FileNameDisplay<'a>;
 
-    fn for_scope(&self, sess: &Session, scopes: RemapPathScopeComponents) -> Self::Output<'_> {
-        if sess.opts.unstable_opts.remap_path_scope.contains(scopes) {
+    fn for_scope(&self, sess: &Session, scope: RemapPathScopeComponents) -> Self::Output<'_> {
+        assert!(
+            scope.bits().count_ones() == 1,
+            "one and only one scope should be passed to for_scope"
+        );
+        if sess.opts.unstable_opts.remap_path_scope.contains(scope) {
             self.prefer_remapped_unconditionaly()
         } else {
             self.prefer_local()
@@ -1552,8 +1547,12 @@ impl RemapFileNameExt for rustc_span::FileName {
 impl RemapFileNameExt for rustc_span::RealFileName {
     type Output<'a> = &'a Path;
 
-    fn for_scope(&self, sess: &Session, scopes: RemapPathScopeComponents) -> Self::Output<'_> {
-        if sess.opts.unstable_opts.remap_path_scope.contains(scopes) {
+    fn for_scope(&self, sess: &Session, scope: RemapPathScopeComponents) -> Self::Output<'_> {
+        assert!(
+            scope.bits().count_ones() == 1,
+            "one and only one scope should be passed to for_scope"
+        );
+        if sess.opts.unstable_opts.remap_path_scope.contains(scope) {
             self.remapped_path_if_available()
         } else {
             self.local_path_if_available()
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 90a38b26f73..efd5e3727b9 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -425,8 +425,14 @@ symbols! {
         assume,
         assume_init,
         async_await,
+        async_call,
+        async_call_mut,
+        async_call_once,
         async_closure,
+        async_fn,
         async_fn_in_trait,
+        async_fn_mut,
+        async_fn_once,
         async_fn_track_caller,
         async_for_loop,
         async_iterator,
@@ -910,6 +916,7 @@ symbols! {
         io_stderr,
         io_stdout,
         irrefutable_let_patterns,
+        is_val_statically_known,
         isa_attribute,
         isize,
         issue,
@@ -1793,6 +1800,7 @@ symbols! {
         warn,
         wasm_abi,
         wasm_import_module,
+        wasm_preview2,
         wasm_target_feature,
         while_let,
         windows,
diff --git a/compiler/rustc_target/src/spec/base/wasm.rs b/compiler/rustc_target/src/spec/base/wasm.rs
index 87ade9e58cf..4b4d2aca26e 100644
--- a/compiler/rustc_target/src/spec/base/wasm.rs
+++ b/compiler/rustc_target/src/spec/base/wasm.rs
@@ -38,9 +38,6 @@ pub fn options() -> TargetOptions {
                 // supposed to be imported and have all other symbols generate errors if
                 // they remain undefined.
                 concat!($prefix, "--allow-undefined"),
-                // Rust code should never have warnings, and warnings are often
-                // indicative of bugs, let's prevent them.
-                concat!($prefix, "--fatal-warnings"),
                 // LLD only implements C++-like demangling, which doesn't match our own
                 // mangling scheme. Tell LLD to not demangle anything and leave it up to
                 // us to demangle these symbols later. Currently rustc does not perform
diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs
index 884bd23e8cc..ead3be7fd52 100644
--- a/compiler/rustc_target/src/spec/mod.rs
+++ b/compiler/rustc_target/src/spec/mod.rs
@@ -1574,6 +1574,7 @@ supported_targets! {
     ("wasm32-unknown-emscripten", wasm32_unknown_emscripten),
     ("wasm32-unknown-unknown", wasm32_unknown_unknown),
     ("wasm32-wasi", wasm32_wasi),
+    ("wasm32-wasi-preview2", wasm32_wasi_preview2),
     ("wasm32-wasi-preview1-threads", wasm32_wasi_preview1_threads),
     ("wasm64-unknown-unknown", wasm64_unknown_unknown),
 
diff --git a/compiler/rustc_target/src/spec/targets/wasm32_unknown_emscripten.rs b/compiler/rustc_target/src/spec/targets/wasm32_unknown_emscripten.rs
index 394f02ecac4..e9e874297d3 100644
--- a/compiler/rustc_target/src/spec/targets/wasm32_unknown_emscripten.rs
+++ b/compiler/rustc_target/src/spec/targets/wasm32_unknown_emscripten.rs
@@ -5,10 +5,7 @@ use crate::spec::{
 pub fn target() -> Target {
     // Reset flags for non-Em flavors back to empty to satisfy sanity checking tests.
     let pre_link_args = LinkArgs::new();
-    let post_link_args = TargetOptions::link_args(
-        LinkerFlavor::EmCc,
-        &["-sABORTING_MALLOC=0", "-Wl,--fatal-warnings"],
-    );
+    let post_link_args = TargetOptions::link_args(LinkerFlavor::EmCc, &["-sABORTING_MALLOC=0"]);
 
     let opts = TargetOptions {
         os: "emscripten".into(),
diff --git a/compiler/rustc_target/src/spec/targets/wasm32_wasi_preview1_threads.rs b/compiler/rustc_target/src/spec/targets/wasm32_wasi_preview1_threads.rs
index 28ea4cc9ece..389c67f8ae9 100644
--- a/compiler/rustc_target/src/spec/targets/wasm32_wasi_preview1_threads.rs
+++ b/compiler/rustc_target/src/spec/targets/wasm32_wasi_preview1_threads.rs
@@ -72,11 +72,12 @@
 //! best we can with this target. Don't start relying on too much here unless
 //! you know what you're getting in to!
 
-use crate::spec::{base, crt_objects, Cc, LinkSelfContainedDefault, LinkerFlavor, Target};
+use crate::spec::{base, crt_objects, cvs, Cc, LinkSelfContainedDefault, LinkerFlavor, Target};
 
 pub fn target() -> Target {
     let mut options = base::wasm::options();
 
+    options.families = cvs!["wasm", "wasi"];
     options.os = "wasi".into();
 
     options.add_pre_link_args(
diff --git a/compiler/rustc_target/src/spec/targets/wasm32_wasi_preview2.rs b/compiler/rustc_target/src/spec/targets/wasm32_wasi_preview2.rs
new file mode 100644
index 00000000000..fc44e5d4cbc
--- /dev/null
+++ b/compiler/rustc_target/src/spec/targets/wasm32_wasi_preview2.rs
@@ -0,0 +1,64 @@
+//! The `wasm32-wasi-preview2` target is the next evolution of the
+//! wasm32-wasi target. While the wasi specification is still under
+//! active development, the {review 2 iteration is considered an "island
+//! of stability" that should allow users to rely on it indefinitely.
+//!
+//! The `wasi` target is a proposal to define a standardized set of WebAssembly
+//! component imports that allow it to interoperate with the host system in a
+//! standardized way. This set of imports is intended to empower WebAssembly
+//! binaries with host capabilities such as filesystem access, network access, etc.
+//!
+//! Wasi Preview 2 relies on the WebAssembly component model which is an extension of
+//! the core WebAssembly specification which allows interoperability between WebAssembly
+//! modules (known as "components") through high-level, shared-nothing APIs instead of the
+//! low-level, shared-everything linear memory model of the core WebAssembly specification.
+//!
+//! You can see more about wasi at <https://wasi.dev> and the component model at
+//! <https://github.com/WebAssembly/component-model>.
+
+use crate::spec::crt_objects;
+use crate::spec::LinkSelfContainedDefault;
+use crate::spec::{base, Target};
+
+pub fn target() -> Target {
+    let mut options = base::wasm::options();
+
+    options.os = "wasi".into();
+    options.env = "preview2".into();
+    options.linker = Some("wasm-component-ld".into());
+
+    options.pre_link_objects_self_contained = crt_objects::pre_wasi_self_contained();
+    options.post_link_objects_self_contained = crt_objects::post_wasi_self_contained();
+
+    // FIXME: Figure out cases in which WASM needs to link with a native toolchain.
+    options.link_self_contained = LinkSelfContainedDefault::True;
+
+    // Right now this is a bit of a workaround but we're currently saying that
+    // the target by default has a static crt which we're taking as a signal
+    // for "use the bundled crt". If that's turned off then the system's crt
+    // will be used, but this means that default usage of this target doesn't
+    // need an external compiler but it's still interoperable with an external
+    // compiler if configured correctly.
+    options.crt_static_default = true;
+    options.crt_static_respected = true;
+
+    // Allow `+crt-static` to create a "cdylib" output which is just a wasm file
+    // without a main function.
+    options.crt_static_allows_dylibs = true;
+
+    // WASI's `sys::args::init` function ignores its arguments; instead,
+    // `args::args()` makes the WASI API calls itself.
+    options.main_needs_argc_argv = false;
+
+    // And, WASI mangles the name of "main" to distinguish between different
+    // signatures.
+    options.entry_name = "__main_void".into();
+
+    Target {
+        llvm_target: "wasm32-unknown-unknown".into(),
+        pointer_width: 32,
+        data_layout: "e-m:e-p:32:32-p10:8:8-p20:8:8-i64:64-n32:64-S128-ni:1:10:20".into(),
+        arch: "wasm32".into(),
+        options,
+    }
+}
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 e31aaaa1969..6a40ffebdad 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
@@ -7,7 +7,7 @@ use super::{
 
 use crate::errors;
 use crate::infer::InferCtxt;
-use crate::traits::{NormalizeExt, ObligationCtxt};
+use crate::traits::{ImplDerivedObligationCause, NormalizeExt, ObligationCtxt};
 
 use hir::def::CtorOf;
 use rustc_data_structures::fx::FxHashSet;
@@ -2973,7 +2973,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
             | ObligationCauseCode::ObjectTypeBound(..) => {}
             ObligationCauseCode::RustCall => {
                 if let Some(pred) = predicate.to_opt_poly_trait_pred()
-                    && Some(pred.def_id()) == self.tcx.lang_items().sized_trait()
+                    && Some(pred.def_id()) == tcx.lang_items().sized_trait()
                 {
                     err.note("argument required to be sized due to `extern \"rust-call\"` ABI");
                 }
@@ -3022,15 +3022,15 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                         let def_id = trait_pred.def_id();
                         let visible_item = if let Some(local) = def_id.as_local() {
                             // Check for local traits being reachable.
-                            let vis = &self.tcx.resolutions(()).effective_visibilities;
+                            let vis = &tcx.resolutions(()).effective_visibilities;
                             // Account for non-`pub` traits in the root of the local crate.
-                            let is_locally_reachable = self.tcx.parent(def_id).is_crate_root();
+                            let is_locally_reachable = tcx.parent(def_id).is_crate_root();
                             vis.is_reachable(local) || is_locally_reachable
                         } else {
                             // Check for foreign traits being reachable.
-                            self.tcx.visible_parent_map(()).get(&def_id).is_some()
+                            tcx.visible_parent_map(()).get(&def_id).is_some()
                         };
-                        if Some(def_id) == self.tcx.lang_items().sized_trait()
+                        if Some(def_id) == tcx.lang_items().sized_trait()
                             && let Some(hir::Node::TraitItem(hir::TraitItem {
                                 ident,
                                 kind: hir::TraitItemKind::Type(bounds, None),
@@ -3039,7 +3039,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                             // Do not suggest relaxing if there is an explicit `Sized` obligation.
                             && !bounds.iter()
                                 .filter_map(|bound| bound.trait_ref())
-                                .any(|tr| tr.trait_def_id() == self.tcx.lang_items().sized_trait())
+                                .any(|tr| tr.trait_def_id() == tcx.lang_items().sized_trait())
                         {
                             let (span, separator) = if let [.., last] = bounds {
                                 (last.span().shrink_to_hi(), " +")
@@ -3102,10 +3102,8 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
             }
             ObligationCauseCode::Coercion { source, target } => {
                 let mut file = None;
-                let source =
-                    self.tcx.short_ty_string(self.resolve_vars_if_possible(source), &mut file);
-                let target =
-                    self.tcx.short_ty_string(self.resolve_vars_if_possible(target), &mut file);
+                let source = tcx.short_ty_string(self.resolve_vars_if_possible(source), &mut file);
+                let target = tcx.short_ty_string(self.resolve_vars_if_possible(target), &mut file);
                 err.note(with_forced_trimmed_paths!(format!(
                     "required for the cast from `{source}` to `{target}`",
                 )));
@@ -3155,10 +3153,10 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 } else {
                     // FIXME: we may suggest array::repeat instead
                     err.help("consider using `core::array::from_fn` to initialize the array");
-                    err.help("see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html# for more information");
+                    err.help("see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html for more information");
                 }
 
-                if self.tcx.sess.is_nightly_build()
+                if tcx.sess.is_nightly_build()
                     && matches!(is_constable, IsConstable::Fn | IsConstable::Ctor)
                 {
                     err.help(
@@ -3168,8 +3166,8 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 }
             }
             ObligationCauseCode::VariableType(hir_id) => {
-                let parent_node = self.tcx.hir().parent_id(hir_id);
-                match self.tcx.opt_hir_node(parent_node) {
+                let parent_node = tcx.hir().parent_id(hir_id);
+                match tcx.opt_hir_node(parent_node) {
                     Some(Node::Local(hir::Local { ty: Some(ty), .. })) => {
                         err.span_suggestion_verbose(
                             ty.span.shrink_to_lo(),
@@ -3207,7 +3205,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                         err.note("all local variables must have a statically known size");
                     }
                 }
-                if !self.tcx.features().unsized_locals {
+                if !tcx.features().unsized_locals {
                     err.help("unsized locals are gated as an unstable feature");
                 }
             }
@@ -3289,7 +3287,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                     err.note("all function arguments must have a statically known size");
                 }
                 if tcx.sess.opts.unstable_features.is_nightly_build()
-                    && !self.tcx.features().unsized_fn_params
+                    && !tcx.features().unsized_fn_params
                 {
                     err.help("unsized fn params are gated as an unstable feature");
                 }
@@ -3358,7 +3356,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                     "all values captured by value by a closure must have a statically known size",
                 );
                 let hir::ExprKind::Closure(closure) =
-                    self.tcx.hir_node_by_def_id(closure_def_id).expect_expr().kind
+                    tcx.hir_node_by_def_id(closure_def_id).expect_expr().kind
                 else {
                     bug!("expected closure in SizedClosureCapture obligation");
                 };
@@ -3369,7 +3367,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 }
             }
             ObligationCauseCode::SizedCoroutineInterior(coroutine_def_id) => {
-                let what = match self.tcx.coroutine_kind(coroutine_def_id) {
+                let what = match tcx.coroutine_kind(coroutine_def_id) {
                     None
                     | Some(hir::CoroutineKind::Coroutine(_))
                     | Some(hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Gen, _)) => {
@@ -3420,10 +3418,10 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 'print: {
                     if !is_upvar_tys_infer_tuple {
                         let mut file = None;
-                        let ty_str = self.tcx.short_ty_string(ty, &mut file);
+                        let ty_str = tcx.short_ty_string(ty, &mut file);
                         let msg = format!("required because it appears within the type `{ty_str}`");
                         match ty.kind() {
-                            ty::Adt(def, _) => match self.tcx.opt_item_ident(def.did()) {
+                            ty::Adt(def, _) => match tcx.opt_item_ident(def.did()) {
                                 Some(ident) => err.span_note(ident.span, msg),
                                 None => err.note(msg),
                             },
@@ -3446,7 +3444,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                                 {
                                     break 'print;
                                 }
-                                err.span_note(self.tcx.def_span(def_id), msg)
+                                err.span_note(tcx.def_span(def_id), msg)
                             }
                             ty::CoroutineWitness(def_id, args) => {
                                 use std::fmt::Write;
@@ -3463,7 +3461,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                                 err.note(msg.trim_end_matches(", ").to_string())
                             }
                             ty::Coroutine(def_id, _) => {
-                                let sp = self.tcx.def_span(def_id);
+                                let sp = tcx.def_span(def_id);
 
                                 // Special-case this to say "async block" instead of `[static coroutine]`.
                                 let kind = tcx.coroutine_kind(def_id).unwrap();
@@ -3475,7 +3473,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                                 )
                             }
                             ty::Closure(def_id, _) => err.span_note(
-                                self.tcx.def_span(def_id),
+                                tcx.def_span(def_id),
                                 "required because it's used within this closure",
                             ),
                             ty::Str => err.note("`str` is considered to contain a `[u8]` slice for auto trait purposes"),
@@ -3519,14 +3517,12 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                     self.resolve_vars_if_possible(data.derived.parent_trait_pred);
                 let parent_def_id = parent_trait_pred.def_id();
                 let mut file = None;
-                let self_ty =
-                    self.tcx.short_ty_string(parent_trait_pred.skip_binder().self_ty(), &mut file);
-                let msg = format!(
-                    "required for `{self_ty}` to implement `{}`",
-                    parent_trait_pred.print_modifiers_and_trait_path()
-                );
+                let self_ty_str =
+                    tcx.short_ty_string(parent_trait_pred.skip_binder().self_ty(), &mut file);
+                let trait_name = parent_trait_pred.print_modifiers_and_trait_path().to_string();
+                let msg = format!("required for `{self_ty_str}` to implement `{trait_name}`");
                 let mut is_auto_trait = false;
-                match self.tcx.hir().get_if_local(data.impl_or_alias_def_id) {
+                match tcx.hir().get_if_local(data.impl_or_alias_def_id) {
                     Some(Node::Item(hir::Item {
                         kind: hir::ItemKind::Trait(is_auto, ..),
                         ident,
@@ -3538,7 +3534,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                         err.span_note(ident.span, msg);
                     }
                     Some(Node::Item(hir::Item {
-                        kind: hir::ItemKind::Impl(hir::Impl { of_trait, self_ty, .. }),
+                        kind: hir::ItemKind::Impl(hir::Impl { of_trait, self_ty, generics, .. }),
                         ..
                     })) => {
                         let mut spans = Vec::with_capacity(2);
@@ -3565,6 +3561,15 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                             );
                         }
                         err.span_note(spans, msg);
+                        point_at_assoc_type_restriction(
+                            tcx,
+                            err,
+                            &self_ty_str,
+                            &trait_name,
+                            predicate,
+                            &generics,
+                            &data,
+                        );
                     }
                     _ => {
                         err.note(msg);
@@ -3618,9 +3623,8 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                         pluralize!(count)
                     ));
                     let mut file = None;
-                    let self_ty = self
-                        .tcx
-                        .short_ty_string(parent_trait_pred.skip_binder().self_ty(), &mut file);
+                    let self_ty =
+                        tcx.short_ty_string(parent_trait_pred.skip_binder().self_ty(), &mut file);
                     err.note(format!(
                         "required for `{self_ty}` to implement `{}`",
                         parent_trait_pred.print_modifiers_and_trait_path()
@@ -3678,10 +3682,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 multispan.push_span_label(span, "required by this bound");
                 err.span_note(
                     multispan,
-                    format!(
-                        "required by a bound on the type alias `{}`",
-                        self.infcx.tcx.item_name(def_id)
-                    ),
+                    format!("required by a bound on the type alias `{}`", tcx.item_name(def_id)),
                 );
             }
             ObligationCauseCode::FunctionArgumentObligation {
@@ -3712,25 +3713,23 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 });
             }
             ObligationCauseCode::CompareImplItemObligation { trait_item_def_id, kind, .. } => {
-                let item_name = self.tcx.item_name(trait_item_def_id);
+                let item_name = tcx.item_name(trait_item_def_id);
                 let msg = format!(
                     "the requirement `{predicate}` appears on the `impl`'s {kind} \
                      `{item_name}` but not on the corresponding trait's {kind}",
                 );
-                let sp = self
-                    .tcx
+                let sp = tcx
                     .opt_item_ident(trait_item_def_id)
                     .map(|i| i.span)
-                    .unwrap_or_else(|| self.tcx.def_span(trait_item_def_id));
+                    .unwrap_or_else(|| tcx.def_span(trait_item_def_id));
                 let mut assoc_span: MultiSpan = sp.into();
                 assoc_span.push_span_label(
                     sp,
                     format!("this trait's {kind} doesn't have the requirement `{predicate}`"),
                 );
-                if let Some(ident) = self
-                    .tcx
+                if let Some(ident) = tcx
                     .opt_associated_item(trait_item_def_id)
-                    .and_then(|i| self.tcx.opt_item_ident(i.container_id(self.tcx)))
+                    .and_then(|i| tcx.opt_item_ident(i.container_id(tcx)))
                 {
                     assoc_span.push_span_label(ident.span, "in this trait");
                 }
@@ -4820,6 +4819,29 @@ fn hint_missing_borrow<'tcx>(
     }
 }
 
+/// Collect all the paths that reference `Self`.
+/// Used to suggest replacing associated types with an explicit type in `where` clauses.
+#[derive(Debug)]
+pub struct SelfVisitor<'v> {
+    pub paths: Vec<&'v hir::Ty<'v>>,
+    pub name: Option<Symbol>,
+}
+
+impl<'v> Visitor<'v> for SelfVisitor<'v> {
+    fn visit_ty(&mut self, ty: &'v hir::Ty<'v>) {
+        if let hir::TyKind::Path(path) = ty.kind
+            && let hir::QPath::TypeRelative(inner_ty, segment) = path
+            && (Some(segment.ident.name) == self.name || self.name.is_none())
+            && let hir::TyKind::Path(inner_path) = inner_ty.kind
+            && let hir::QPath::Resolved(None, inner_path) = inner_path
+            && let Res::SelfTyAlias { .. } = inner_path.res
+        {
+            self.paths.push(ty);
+        }
+        hir::intravisit::walk_ty(self, ty);
+    }
+}
+
 /// Collect all the returned expressions within the input expression.
 /// Used to point at the return spans when we want to suggest some change to them.
 #[derive(Default)]
@@ -5064,6 +5086,134 @@ pub fn suggest_desugaring_async_fn_to_impl_future_in_trait<'tcx>(
     Some(sugg)
 }
 
+/// On `impl` evaluation cycles, look for `Self::AssocTy` restrictions in `where` clauses, explain
+/// they are not allowed and if possible suggest alternatives.
+fn point_at_assoc_type_restriction(
+    tcx: TyCtxt<'_>,
+    err: &mut Diagnostic,
+    self_ty_str: &str,
+    trait_name: &str,
+    predicate: ty::Predicate<'_>,
+    generics: &hir::Generics<'_>,
+    data: &ImplDerivedObligationCause<'_>,
+) {
+    let ty::PredicateKind::Clause(clause) = predicate.kind().skip_binder() else {
+        return;
+    };
+    let ty::ClauseKind::Projection(proj) = clause else {
+        return;
+    };
+    let name = tcx.item_name(proj.projection_ty.def_id);
+    let mut predicates = generics.predicates.iter().peekable();
+    let mut prev: Option<&hir::WhereBoundPredicate<'_>> = None;
+    while let Some(pred) = predicates.next() {
+        let hir::WherePredicate::BoundPredicate(pred) = pred else {
+            continue;
+        };
+        let mut bounds = pred.bounds.iter().peekable();
+        while let Some(bound) = bounds.next() {
+            let Some(trait_ref) = bound.trait_ref() else {
+                continue;
+            };
+            if bound.span() != data.span {
+                continue;
+            }
+            if let hir::TyKind::Path(path) = pred.bounded_ty.kind
+                && let hir::QPath::TypeRelative(ty, segment) = path
+                && segment.ident.name == name
+                && let hir::TyKind::Path(inner_path) = ty.kind
+                && let hir::QPath::Resolved(None, inner_path) = inner_path
+                && let Res::SelfTyAlias { .. } = inner_path.res
+            {
+                // The following block is to determine the right span to delete for this bound
+                // that will leave valid code after the suggestion is applied.
+                let span = if pred.origin == hir::PredicateOrigin::WhereClause
+                    && generics
+                        .predicates
+                        .iter()
+                        .filter(|p| {
+                            matches!(
+                                p,
+                                hir::WherePredicate::BoundPredicate(p)
+                                if hir::PredicateOrigin::WhereClause == p.origin
+                            )
+                        })
+                        .count()
+                        == 1
+                {
+                    // There's only one `where` bound, that needs to be removed. Remove the whole
+                    // `where` clause.
+                    generics.where_clause_span
+                } else if let Some(hir::WherePredicate::BoundPredicate(next)) = predicates.peek()
+                    && pred.origin == next.origin
+                {
+                    // There's another bound, include the comma for the current one.
+                    pred.span.until(next.span)
+                } else if let Some(prev) = prev
+                    && pred.origin == prev.origin
+                {
+                    // Last bound, try to remove the previous comma.
+                    prev.span.shrink_to_hi().to(pred.span)
+                } else if pred.origin == hir::PredicateOrigin::WhereClause {
+                    pred.span.with_hi(generics.where_clause_span.hi())
+                } else {
+                    pred.span
+                };
+
+                err.span_suggestion_verbose(
+                    span,
+                    "associated type for the current `impl` cannot be restricted in `where` \
+                     clauses, remove this bound",
+                    "",
+                    Applicability::MaybeIncorrect,
+                );
+            }
+            if let Some(new) =
+                tcx.associated_items(data.impl_or_alias_def_id).find_by_name_and_kind(
+                    tcx,
+                    Ident::with_dummy_span(name),
+                    ty::AssocKind::Type,
+                    data.impl_or_alias_def_id,
+                )
+            {
+                // The associated type is specified in the `impl` we're
+                // looking at. Point at it.
+                let span = tcx.def_span(new.def_id);
+                err.span_label(
+                    span,
+                    format!(
+                        "associated type `<{self_ty_str} as {trait_name}>::{name}` is specified \
+                         here",
+                    ),
+                );
+                // Search for the associated type `Self::{name}`, get
+                // its type and suggest replacing the bound with it.
+                let mut visitor = SelfVisitor { paths: vec![], name: Some(name) };
+                visitor.visit_trait_ref(trait_ref);
+                for path in visitor.paths {
+                    err.span_suggestion_verbose(
+                        path.span,
+                        "replace the associated type with the type specified in this `impl`",
+                        tcx.type_of(new.def_id).skip_binder().to_string(),
+                        Applicability::MachineApplicable,
+                    );
+                }
+            } else {
+                let mut visitor = SelfVisitor { paths: vec![], name: None };
+                visitor.visit_trait_ref(trait_ref);
+                let span: MultiSpan =
+                    visitor.paths.iter().map(|p| p.span).collect::<Vec<Span>>().into();
+                err.span_note(
+                    span,
+                    "associated types for the current `impl` cannot be restricted in `where` \
+                     clauses",
+                );
+            }
+        }
+        prev = Some(pred);
+    }
+}
+
 fn get_deref_type_and_refs(mut ty: Ty<'_>) -> (Ty<'_>, Vec<hir::Mutability>) {
     let mut refs = vec![];
 
diff --git a/library/core/src/intrinsics.rs b/library/core/src/intrinsics.rs
index 5d917dc6fbb..76a53a9366a 100644
--- a/library/core/src/intrinsics.rs
+++ b/library/core/src/intrinsics.rs
@@ -2517,6 +2517,66 @@ extern "rust-intrinsic" {
     where
         G: FnOnce<ARG, Output = RET>,
         F: FnOnce<ARG, Output = RET>;
+
+    /// Returns whether the argument's value is statically known at
+    /// compile-time.
+    ///
+    /// This is useful when there is a way of writing the code that will
+    /// be *faster* when some variables have known values, but *slower*
+    /// in the general case: an `if is_val_statically_known(var)` can be used
+    /// to select between these two variants. The `if` will be optimized away
+    /// and only the desired branch remains.
+    ///
+    /// Formally speaking, this function non-deterministically returns `true`
+    /// or `false`, and the caller has to ensure sound behavior for both cases.
+    /// In other words, the following code has *Undefined Behavior*:
+    ///
+    /// ```
+    /// #![feature(is_val_statically_known)]
+    /// #![feature(core_intrinsics)]
+    /// # #![allow(internal_features)]
+    /// use std::hint::unreachable_unchecked;
+    /// use std::intrinsics::is_val_statically_known;
+    ///
+    /// unsafe {
+    ///    if !is_val_statically_known(0) { unreachable_unchecked(); }
+    /// }
+    /// ```
+    ///
+    /// This also means that the following code's behavior is unspecified; it
+    /// may panic, or it may not:
+    ///
+    /// ```no_run
+    /// #![feature(is_val_statically_known)]
+    /// #![feature(core_intrinsics)]
+    /// # #![allow(internal_features)]
+    /// use std::intrinsics::is_val_statically_known;
+    ///
+    /// unsafe {
+    ///     assert_eq!(is_val_statically_known(0), is_val_statically_known(0));
+    /// }
+    /// ```
+    ///
+    /// Unsafe code may not rely on `is_val_statically_known` returning any
+    /// particular value, ever. However, the compiler will generally make it
+    /// return `true` only if the value of the argument is actually known.
+    ///
+    /// When calling this in a `const fn`, both paths must be semantically
+    /// equivalent, that is, the result of the `true` branch and the `false`
+    /// branch must return the same value and have the same side-effects *no
+    /// matter what*.
+    #[rustc_const_unstable(feature = "is_val_statically_known", issue = "none")]
+    #[rustc_nounwind]
+    #[cfg(not(bootstrap))]
+    pub fn is_val_statically_known<T: Copy>(arg: T) -> bool;
+}
+
+// FIXME: Seems using `unstable` here completely ignores `rustc_allow_const_fn_unstable`
+// and thus compiling stage0 core doesn't work.
+#[rustc_const_stable(feature = "is_val_statically_known", since = "0.0.0")]
+#[cfg(bootstrap)]
+pub const unsafe fn is_val_statically_known<T: Copy>(_arg: T) -> bool {
+    false
 }
 
 // Some functions are defined here because they accidentally got made
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index ead8cbe0e2f..2af242d4b50 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -200,6 +200,7 @@
 //
 // Language features:
 // tidy-alphabetical-start
+#![cfg_attr(not(bootstrap), feature(is_val_statically_known))]
 #![feature(abi_unadjusted)]
 #![feature(adt_const_params)]
 #![feature(allow_internal_unsafe)]
diff --git a/library/core/src/num/int_macros.rs b/library/core/src/num/int_macros.rs
index d052dcc3e6e..bb35b6128ea 100644
--- a/library/core/src/num/int_macros.rs
+++ b/library/core/src/num/int_macros.rs
@@ -1374,26 +1374,59 @@ macro_rules! int_impl {
         #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
+        #[rustc_allow_const_fn_unstable(is_val_statically_known, const_int_unchecked_arith)]
         #[inline]
         pub const fn checked_pow(self, mut exp: u32) -> Option<Self> {
-            if exp == 0 {
-                return Some(1);
-            }
-            let mut base = self;
-            let mut acc: Self = 1;
-
-            while exp > 1 {
-                if (exp & 1) == 1 {
-                    acc = try_opt!(acc.checked_mul(base));
+            // SAFETY: This path has the same behavior as the other.
+            if unsafe { intrinsics::is_val_statically_known(self) }
+                && self.unsigned_abs().is_power_of_two()
+            {
+                if self == 1 { // Avoid divide by zero
+                    return Some(1);
                 }
-                exp /= 2;
-                base = try_opt!(base.checked_mul(base));
+                if self == -1 { // Avoid divide by zero
+                    return Some(if exp & 1 != 0 { -1 } else { 1 });
+                }
+                // SAFETY: We just checked this is a power of two. and above zero.
+                let power_used = unsafe { intrinsics::cttz_nonzero(self.wrapping_abs()) as u32 };
+                if exp > Self::BITS / power_used { return None; } // Division of constants is free
+
+                // SAFETY: exp <= Self::BITS / power_used
+                let res = unsafe { intrinsics::unchecked_shl(
+                    1 as Self,
+                    intrinsics::unchecked_mul(power_used, exp) as Self
+                )};
+                // LLVM doesn't always optimize out the checks
+                // at the ir level.
+
+                let sign = self.is_negative() && exp & 1 != 0;
+                if !sign && res == Self::MIN  {
+                    None
+                } else if sign {
+                    Some(res.wrapping_neg())
+                } else {
+                    Some(res)
+                }
+            } else {
+                if exp == 0 {
+                    return Some(1);
+                }
+                let mut base = self;
+                let mut acc: Self = 1;
+
+                while exp > 1 {
+                    if (exp & 1) == 1 {
+                        acc = try_opt!(acc.checked_mul(base));
+                    }
+                    exp /= 2;
+                    base = try_opt!(base.checked_mul(base));
+                }
+                // since exp!=0, finally the exp must be 1.
+                // Deal with the final bit of the exponent separately, since
+                // squaring the base afterwards is not necessary and may cause a
+                // needless overflow.
+                acc.checked_mul(base)
             }
-            // since exp!=0, finally the exp must be 1.
-            // Deal with the final bit of the exponent separately, since
-            // squaring the base afterwards is not necessary and may cause a
-            // needless overflow.
-            acc.checked_mul(base)
         }
 
         /// Strict exponentiation. Computes `self.pow(exp)`, panicking if
@@ -2058,27 +2091,58 @@ macro_rules! int_impl {
         #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
+        #[rustc_allow_const_fn_unstable(is_val_statically_known, const_int_unchecked_arith)]
         #[inline]
         pub const fn wrapping_pow(self, mut exp: u32) -> Self {
-            if exp == 0 {
-                return 1;
-            }
-            let mut base = self;
-            let mut acc: Self = 1;
-
-            while exp > 1 {
-                if (exp & 1) == 1 {
-                    acc = acc.wrapping_mul(base);
+            // SAFETY: This path has the same behavior as the other.
+            if unsafe { intrinsics::is_val_statically_known(self) }
+                && self.unsigned_abs().is_power_of_two()
+            {
+                if self == 1 { // Avoid divide by zero
+                    return 1;
+                }
+                if self == -1 { // Avoid divide by zero
+                    return if exp & 1 != 0 { -1 } else { 1 };
+                }
+                // SAFETY: We just checked this is a power of two. and above zero.
+                let power_used = unsafe { intrinsics::cttz_nonzero(self.wrapping_abs()) as u32 };
+                if exp > Self::BITS / power_used { return 0; } // Division of constants is free
+
+                // SAFETY: exp <= Self::BITS / power_used
+                let res = unsafe { intrinsics::unchecked_shl(
+                    1 as Self,
+                    intrinsics::unchecked_mul(power_used, exp) as Self
+                )};
+                // LLVM doesn't always optimize out the checks
+                // at the ir level.
+
+                let sign = self.is_negative() && exp & 1 != 0;
+                if sign {
+                    res.wrapping_neg()
+                } else {
+                    res
+                }
+            } else {
+                if exp == 0 {
+                    return 1;
+                }
+                let mut base = self;
+                let mut acc: Self = 1;
+
+                while exp > 1 {
+                    if (exp & 1) == 1 {
+                        acc = acc.wrapping_mul(base);
+                    }
+                    exp /= 2;
+                    base = base.wrapping_mul(base);
                 }
-                exp /= 2;
-                base = base.wrapping_mul(base);
-            }
 
-            // since exp!=0, finally the exp must be 1.
-            // Deal with the final bit of the exponent separately, since
-            // squaring the base afterwards is not necessary and may cause a
-            // needless overflow.
-            acc.wrapping_mul(base)
+                // since exp!=0, finally the exp must be 1.
+                // Deal with the final bit of the exponent separately, since
+                // squaring the base afterwards is not necessary and may cause a
+                // needless overflow.
+                acc.wrapping_mul(base)
+            }
         }
 
         /// Calculates `self` + `rhs`
@@ -2561,36 +2625,68 @@ macro_rules! int_impl {
         #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
+        #[rustc_allow_const_fn_unstable(is_val_statically_known, const_int_unchecked_arith)]
         #[inline]
         pub const fn overflowing_pow(self, mut exp: u32) -> (Self, bool) {
-            if exp == 0 {
-                return (1,false);
-            }
-            let mut base = self;
-            let mut acc: Self = 1;
-            let mut overflown = false;
-            // Scratch space for storing results of overflowing_mul.
-            let mut r;
-
-            while exp > 1 {
-                if (exp & 1) == 1 {
-                    r = acc.overflowing_mul(base);
-                    acc = r.0;
+            // SAFETY: This path has the same behavior as the other.
+            if unsafe { intrinsics::is_val_statically_known(self) }
+                && self.unsigned_abs().is_power_of_two()
+            {
+                if self == 1 { // Avoid divide by zero
+                    return (1, false);
+                }
+                if self == -1 { // Avoid divide by zero
+                    return (if exp & 1 != 0 { -1 } else { 1 }, false);
+                }
+                // SAFETY: We just checked this is a power of two. and above zero.
+                let power_used = unsafe { intrinsics::cttz_nonzero(self.wrapping_abs()) as u32 };
+                if exp > Self::BITS / power_used { return (0, true); } // Division of constants is free
+
+                // SAFETY: exp <= Self::BITS / power_used
+                let res = unsafe { intrinsics::unchecked_shl(
+                    1 as Self,
+                    intrinsics::unchecked_mul(power_used, exp) as Self
+                )};
+                // LLVM doesn't always optimize out the checks
+                // at the ir level.
+
+                let sign = self.is_negative() && exp & 1 != 0;
+                let overflow = res == Self::MIN;
+                if sign {
+                    (res.wrapping_neg(), overflow)
+                } else {
+                    (res, overflow)
+                }
+            } else {
+                if exp == 0 {
+                    return (1,false);
+                }
+                let mut base = self;
+                let mut acc: Self = 1;
+                let mut overflown = false;
+                // Scratch space for storing results of overflowing_mul.
+                let mut r;
+
+                while exp > 1 {
+                    if (exp & 1) == 1 {
+                        r = acc.overflowing_mul(base);
+                        acc = r.0;
+                        overflown |= r.1;
+                    }
+                    exp /= 2;
+                    r = base.overflowing_mul(base);
+                    base = r.0;
                     overflown |= r.1;
                 }
-                exp /= 2;
-                r = base.overflowing_mul(base);
-                base = r.0;
-                overflown |= r.1;
-            }
 
-            // since exp!=0, finally the exp must be 1.
-            // Deal with the final bit of the exponent separately, since
-            // squaring the base afterwards is not necessary and may cause a
-            // needless overflow.
-            r = acc.overflowing_mul(base);
-            r.1 |= overflown;
-            r
+                // since exp!=0, finally the exp must be 1.
+                // Deal with the final bit of the exponent separately, since
+                // squaring the base afterwards is not necessary and may cause a
+                // needless overflow.
+                r = acc.overflowing_mul(base);
+                r.1 |= overflown;
+                r
+            }
         }
 
         /// Raises self to the power of `exp`, using exponentiation by squaring.
@@ -2608,28 +2704,68 @@ macro_rules! int_impl {
         #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
+        #[rustc_allow_const_fn_unstable(is_val_statically_known, const_int_unchecked_arith)]
         #[inline]
         #[rustc_inherit_overflow_checks]
+        #[track_caller] // Hides the hackish overflow check for powers of two.
         pub const fn pow(self, mut exp: u32) -> Self {
-            if exp == 0 {
-                return 1;
-            }
-            let mut base = self;
-            let mut acc = 1;
+            // SAFETY: This path has the same behavior as the other.
+            if unsafe { intrinsics::is_val_statically_known(self) }
+                && self.unsigned_abs().is_power_of_two()
+            {
+                if self == 1 { // Avoid divide by zero
+                    return 1;
+                }
+                if self == -1 { // Avoid divide by zero
+                    return if exp & 1 != 0 { -1 } else { 1 };
+                }
+                // SAFETY: We just checked this is a power of two. and above zero.
+                let power_used = unsafe { intrinsics::cttz_nonzero(self.wrapping_abs()) as u32 };
+                if exp > Self::BITS / power_used { // Division of constants is free
+                    #[allow(arithmetic_overflow)]
+                    return Self::MAX * Self::MAX * 0;
+                }
 
-            while exp > 1 {
-                if (exp & 1) == 1 {
-                    acc = acc * base;
+                // SAFETY: exp <= Self::BITS / power_used
+                let res = unsafe { intrinsics::unchecked_shl(
+                    1 as Self,
+                    intrinsics::unchecked_mul(power_used, exp) as Self
+                )};
+                // LLVM doesn't always optimize out the checks
+                // at the ir level.
+
+                let sign = self.is_negative() && exp & 1 != 0;
+                #[allow(arithmetic_overflow)]
+                if !sign && res == Self::MIN  {
+                    // So it panics.
+                    _ = Self::MAX * Self::MAX;
+                }
+                if sign {
+                    res.wrapping_neg()
+                } else {
+                    res
+                }
+            } else {
+                if exp == 0 {
+                    return 1;
+                }
+                let mut base = self;
+                let mut acc = 1;
+
+                while exp > 1 {
+                    if (exp & 1) == 1 {
+                        acc = acc * base;
+                    }
+                    exp /= 2;
+                    base = base * base;
                 }
-                exp /= 2;
-                base = base * base;
-            }
 
-            // since exp!=0, finally the exp must be 1.
-            // Deal with the final bit of the exponent separately, since
-            // squaring the base afterwards is not necessary and may cause a
-            // needless overflow.
-            acc * base
+                // since exp!=0, finally the exp must be 1.
+                // Deal with the final bit of the exponent separately, since
+                // squaring the base afterwards is not necessary and may cause a
+                // needless overflow.
+                acc * base
+            }
         }
 
         /// Returns the square root of the number, rounded down.
diff --git a/library/core/src/num/nonzero.rs b/library/core/src/num/nonzero.rs
index 640f1e3fa85..45ac544ceaa 100644
--- a/library/core/src/num/nonzero.rs
+++ b/library/core/src/num/nonzero.rs
@@ -288,6 +288,43 @@ macro_rules! nonzero_integer {
                 unsafe { intrinsics::cttz_nonzero(self.get() as $UnsignedPrimitive) as u32 }
             }
 
+            /// Returns the number of ones in the binary representation of `self`.
+            ///
+            /// # Examples
+            ///
+            /// Basic usage:
+            ///
+            /// ```
+            /// #![feature(non_zero_count_ones)]
+            /// # fn main() { test().unwrap(); }
+            /// # fn test() -> Option<()> {
+            #[doc = concat!("# use std::num::{self, ", stringify!($Ty), "};")]
+            ///
+            /// let one = num::NonZeroU32::new(1)?;
+            /// let three = num::NonZeroU32::new(3)?;
+            #[doc = concat!("let a = ", stringify!($Ty), "::new(0b100_0000)?;")]
+            #[doc = concat!("let b = ", stringify!($Ty), "::new(0b100_0011)?;")]
+            ///
+            /// assert_eq!(a.count_ones(), one);
+            /// assert_eq!(b.count_ones(), three);
+            /// # Some(())
+            /// # }
+            /// ```
+            ///
+            #[unstable(feature = "non_zero_count_ones", issue = "120287")]
+            #[rustc_const_unstable(feature = "non_zero_count_ones", issue = "120287")]
+            #[doc(alias = "popcount")]
+            #[doc(alias = "popcnt")]
+            #[must_use = "this returns the result of the operation, \
+                        without modifying the original"]
+            #[inline(always)]
+            pub const fn count_ones(self) -> NonZeroU32 {
+                // SAFETY:
+                // `self` is non-zero, which means it has at least one bit set, which means
+                // that the result of `count_ones` is non-zero.
+                unsafe { NonZeroU32::new_unchecked(self.get().count_ones()) }
+            }
+
             nonzero_integer_signedness_dependent_methods! {
                 Self = $Ty,
                 Primitive = $signedness $Int,
diff --git a/library/core/src/num/uint_macros.rs b/library/core/src/num/uint_macros.rs
index a217c2e259d..d450c68a5b2 100644
--- a/library/core/src/num/uint_macros.rs
+++ b/library/core/src/num/uint_macros.rs
@@ -1364,28 +1364,49 @@ macro_rules! uint_impl {
         #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
+        #[rustc_allow_const_fn_unstable(is_val_statically_known, const_int_unchecked_arith)]
         #[inline]
         pub const fn checked_pow(self, mut exp: u32) -> Option<Self> {
-            if exp == 0 {
-                return Some(1);
-            }
-            let mut base = self;
-            let mut acc: Self = 1;
-
-            while exp > 1 {
-                if (exp & 1) == 1 {
-                    acc = try_opt!(acc.checked_mul(base));
+            // SAFETY: This path has the same behavior as the other.
+            if unsafe { intrinsics::is_val_statically_known(self) }
+                && self.is_power_of_two()
+            {
+                if self == 1 { // Avoid divide by zero
+                    return Some(1);
+                }
+                // SAFETY: We just checked this is a power of two. and above zero.
+                let power_used = unsafe { intrinsics::cttz_nonzero(self) as u32 };
+                if exp > Self::BITS / power_used { return None; } // Division of constants is free
+
+                // SAFETY: exp <= Self::BITS / power_used
+                unsafe { Some(intrinsics::unchecked_shl(
+                    1 as Self,
+                    intrinsics::unchecked_mul(power_used, exp) as Self
+                )) }
+                // LLVM doesn't always optimize out the checks
+                // at the ir level.
+            } else {
+                if exp == 0 {
+                    return Some(1);
+                }
+                let mut base = self;
+                let mut acc: Self = 1;
+
+                while exp > 1 {
+                    if (exp & 1) == 1 {
+                        acc = try_opt!(acc.checked_mul(base));
+                    }
+                    exp /= 2;
+                    base = try_opt!(base.checked_mul(base));
                 }
-                exp /= 2;
-                base = try_opt!(base.checked_mul(base));
-            }
 
-            // since exp!=0, finally the exp must be 1.
-            // Deal with the final bit of the exponent separately, since
-            // squaring the base afterwards is not necessary and may cause a
-            // needless overflow.
+                // since exp!=0, finally the exp must be 1.
+                // Deal with the final bit of the exponent separately, since
+                // squaring the base afterwards is not necessary and may cause a
+                // needless overflow.
 
-            acc.checked_mul(base)
+                acc.checked_mul(base)
+            }
         }
 
         /// Strict exponentiation. Computes `self.pow(exp)`, panicking if
@@ -1887,27 +1908,48 @@ macro_rules! uint_impl {
         #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
+        #[rustc_allow_const_fn_unstable(is_val_statically_known, const_int_unchecked_arith)]
         #[inline]
         pub const fn wrapping_pow(self, mut exp: u32) -> Self {
-            if exp == 0 {
-                return 1;
-            }
-            let mut base = self;
-            let mut acc: Self = 1;
-
-            while exp > 1 {
-                if (exp & 1) == 1 {
-                    acc = acc.wrapping_mul(base);
+            // SAFETY: This path has the same behavior as the other.
+            if unsafe { intrinsics::is_val_statically_known(self) }
+                && self.is_power_of_two()
+            {
+                if self == 1 { // Avoid divide by zero
+                    return 1;
+                }
+                // SAFETY: We just checked this is a power of two. and above zero.
+                let power_used = unsafe { intrinsics::cttz_nonzero(self) as u32 };
+                if exp > Self::BITS / power_used {  return 0; } // Division of constants is free
+
+                // SAFETY: exp <= Self::BITS / power_used
+                unsafe { intrinsics::unchecked_shl(
+                    1 as Self,
+                    intrinsics::unchecked_mul(power_used, exp) as Self
+                )}
+                // LLVM doesn't always optimize out the checks
+                // at the ir level.
+            } else {
+                if exp == 0 {
+                    return 1;
+                }
+                let mut base = self;
+                let mut acc: Self = 1;
+
+                while exp > 1 {
+                    if (exp & 1) == 1 {
+                        acc = acc.wrapping_mul(base);
+                    }
+                    exp /= 2;
+                    base = base.wrapping_mul(base);
                 }
-                exp /= 2;
-                base = base.wrapping_mul(base);
-            }
 
-            // since exp!=0, finally the exp must be 1.
-            // Deal with the final bit of the exponent separately, since
-            // squaring the base afterwards is not necessary and may cause a
-            // needless overflow.
-            acc.wrapping_mul(base)
+                // since exp!=0, finally the exp must be 1.
+                // Deal with the final bit of the exponent separately, since
+                // squaring the base afterwards is not necessary and may cause a
+                // needless overflow.
+                acc.wrapping_mul(base)
+            }
         }
 
         /// Calculates `self` + `rhs`
@@ -2341,37 +2383,58 @@ macro_rules! uint_impl {
         #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
+        #[rustc_allow_const_fn_unstable(is_val_statically_known, const_int_unchecked_arith)]
         #[inline]
         pub const fn overflowing_pow(self, mut exp: u32) -> (Self, bool) {
-            if exp == 0{
-                return (1,false);
-            }
-            let mut base = self;
-            let mut acc: Self = 1;
-            let mut overflown = false;
-            // Scratch space for storing results of overflowing_mul.
-            let mut r;
-
-            while exp > 1 {
-                if (exp & 1) == 1 {
-                    r = acc.overflowing_mul(base);
-                    acc = r.0;
+            // SAFETY: This path has the same behavior as the other.
+            if unsafe { intrinsics::is_val_statically_known(self) }
+                && self.is_power_of_two()
+            {
+                if self == 1 { // Avoid divide by zero
+                    return (1, false);
+                }
+                // SAFETY: We just checked this is a power of two. and above zero.
+                let power_used = unsafe { intrinsics::cttz_nonzero(self) as u32 };
+                if exp > Self::BITS / power_used {  return (0, true); } // Division of constants is free
+
+                // SAFETY: exp <= Self::BITS / power_used
+                unsafe { (intrinsics::unchecked_shl(
+                    1 as Self,
+                    intrinsics::unchecked_mul(power_used, exp) as Self
+                ), false) }
+                // LLVM doesn't always optimize out the checks
+                // at the ir level.
+            } else {
+                if exp == 0{
+                    return (1,false);
+                }
+                let mut base = self;
+                let mut acc: Self = 1;
+                let mut overflown = false;
+                // Scratch space for storing results of overflowing_mul.
+                let mut r;
+
+                while exp > 1 {
+                    if (exp & 1) == 1 {
+                        r = acc.overflowing_mul(base);
+                        acc = r.0;
+                        overflown |= r.1;
+                    }
+                    exp /= 2;
+                    r = base.overflowing_mul(base);
+                    base = r.0;
                     overflown |= r.1;
                 }
-                exp /= 2;
-                r = base.overflowing_mul(base);
-                base = r.0;
-                overflown |= r.1;
-            }
 
-            // since exp!=0, finally the exp must be 1.
-            // Deal with the final bit of the exponent separately, since
-            // squaring the base afterwards is not necessary and may cause a
-            // needless overflow.
-            r = acc.overflowing_mul(base);
-            r.1 |= overflown;
+                // since exp!=0, finally the exp must be 1.
+                // Deal with the final bit of the exponent separately, since
+                // squaring the base afterwards is not necessary and may cause a
+                // needless overflow.
+                r = acc.overflowing_mul(base);
+                r.1 |= overflown;
 
-            r
+                r
+            }
         }
 
         /// Raises self to the power of `exp`, using exponentiation by squaring.
@@ -2387,28 +2450,64 @@ macro_rules! uint_impl {
         #[rustc_const_stable(feature = "const_int_pow", since = "1.50.0")]
         #[must_use = "this returns the result of the operation, \
                       without modifying the original"]
+        #[rustc_allow_const_fn_unstable(is_val_statically_known, const_int_unchecked_arith)]
         #[inline]
         #[rustc_inherit_overflow_checks]
+        #[track_caller] // Hides the hackish overflow check for powers of two.
         pub const fn pow(self, mut exp: u32) -> Self {
-            if exp == 0 {
-                return 1;
-            }
-            let mut base = self;
-            let mut acc = 1;
+            // LLVM now knows that `self` is a constant value, but not a
+            // constant in Rust. This allows us to compute the power used at
+            // compile-time.
+            //
+            // This will likely add a branch in debug builds, but this should
+            // be ok.
+            //
+            // This is a massive performance boost in release builds as you can
+            // get the power of a power of two and the exponent through a `shl`
+            // instruction, but we must add a couple more checks for parity with
+            // our own `pow`.
+            // SAFETY: This path has the same behavior as the other.
+            if unsafe { intrinsics::is_val_statically_known(self) }
+                && self.is_power_of_two()
+            {
+                if self == 1 { // Avoid divide by zero
+                    return 1;
+                }
+                // SAFETY: We just checked this is a power of two. and above zero.
+                let power_used = unsafe { intrinsics::cttz_nonzero(self) as u32 };
+                if exp > Self::BITS / power_used { // Division of constants is free
+                    #[allow(arithmetic_overflow)]
+                    return Self::MAX * Self::MAX * 0;
+                }
 
-            while exp > 1 {
-                if (exp & 1) == 1 {
-                    acc = acc * base;
+                // SAFETY: exp <= Self::BITS / power_used
+                unsafe { intrinsics::unchecked_shl(
+                    1 as Self,
+                    intrinsics::unchecked_mul(power_used, exp) as Self
+                )}
+                // LLVM doesn't always optimize out the checks
+                // at the ir level.
+            } else {
+                if exp == 0 {
+                    return 1;
+                }
+                let mut base = self;
+                let mut acc = 1;
+
+                while exp > 1 {
+                    if (exp & 1) == 1 {
+                        acc = acc * base;
+                    }
+                    exp /= 2;
+                    base = base * base;
                 }
-                exp /= 2;
-                base = base * base;
-            }
 
-            // since exp!=0, finally the exp must be 1.
-            // Deal with the final bit of the exponent separately, since
-            // squaring the base afterwards is not necessary and may cause a
-            // needless overflow.
-            acc * base
+                // since exp!=0, finally the exp must be 1.
+                // Deal with the final bit of the exponent separately, since
+                // squaring the base afterwards is not necessary and may cause a
+                // needless overflow.
+                acc * base
+            }
         }
 
         /// Returns the square root of the number, rounded down.
diff --git a/library/core/src/ops/async_function.rs b/library/core/src/ops/async_function.rs
new file mode 100644
index 00000000000..965873f163e
--- /dev/null
+++ b/library/core/src/ops/async_function.rs
@@ -0,0 +1,108 @@
+use crate::future::Future;
+use crate::marker::Tuple;
+
+/// An async-aware version of the [`Fn`](crate::ops::Fn) trait.
+///
+/// All `async fn` and functions returning futures implement this trait.
+#[unstable(feature = "async_fn_traits", issue = "none")]
+#[rustc_paren_sugar]
+#[fundamental]
+#[must_use = "async closures are lazy and do nothing unless called"]
+#[cfg_attr(not(bootstrap), lang = "async_fn")]
+pub trait AsyncFn<Args: Tuple>: AsyncFnMut<Args> {
+    /// Future returned by [`AsyncFn::async_call`].
+    #[unstable(feature = "async_fn_traits", issue = "none")]
+    type CallFuture<'a>: Future<Output = Self::Output>
+    where
+        Self: 'a;
+
+    /// Call the [`AsyncFn`], returning a future which may borrow from the called closure.
+    #[unstable(feature = "async_fn_traits", issue = "none")]
+    extern "rust-call" fn async_call(&self, args: Args) -> Self::CallFuture<'_>;
+}
+
+/// An async-aware version of the [`FnMut`](crate::ops::FnMut) trait.
+///
+/// All `async fn` and functions returning futures implement this trait.
+#[unstable(feature = "async_fn_traits", issue = "none")]
+#[rustc_paren_sugar]
+#[fundamental]
+#[must_use = "async closures are lazy and do nothing unless called"]
+#[cfg_attr(not(bootstrap), lang = "async_fn_mut")]
+pub trait AsyncFnMut<Args: Tuple>: AsyncFnOnce<Args> {
+    /// Future returned by [`AsyncFnMut::async_call_mut`].
+    #[unstable(feature = "async_fn_traits", issue = "none")]
+    type CallMutFuture<'a>: Future<Output = Self::Output>
+    where
+        Self: 'a;
+
+    /// Call the [`AsyncFnMut`], returning a future which may borrow from the called closure.
+    #[unstable(feature = "async_fn_traits", issue = "none")]
+    extern "rust-call" fn async_call_mut(&mut self, args: Args) -> Self::CallMutFuture<'_>;
+}
+
+/// An async-aware version of the [`FnOnce`](crate::ops::FnOnce) trait.
+///
+/// All `async fn` and functions returning futures implement this trait.
+#[unstable(feature = "async_fn_traits", issue = "none")]
+#[rustc_paren_sugar]
+#[fundamental]
+#[must_use = "async closures are lazy and do nothing unless called"]
+#[cfg_attr(not(bootstrap), lang = "async_fn_once")]
+pub trait AsyncFnOnce<Args: Tuple> {
+    /// Future returned by [`AsyncFnOnce::async_call_once`].
+    #[unstable(feature = "async_fn_traits", issue = "none")]
+    type CallOnceFuture: Future<Output = Self::Output>;
+
+    /// Output type of the called closure's future.
+    #[unstable(feature = "async_fn_traits", issue = "none")]
+    type Output;
+
+    /// Call the [`AsyncFnOnce`], returning a future which may move out of the called closure.
+    #[unstable(feature = "async_fn_traits", issue = "none")]
+    extern "rust-call" fn async_call_once(self, args: Args) -> Self::CallOnceFuture;
+}
+
+mod impls {
+    use super::{AsyncFn, AsyncFnMut, AsyncFnOnce};
+    use crate::future::Future;
+    use crate::marker::Tuple;
+
+    #[unstable(feature = "async_fn_traits", issue = "none")]
+    impl<F: Fn<A>, A: Tuple> AsyncFn<A> for F
+    where
+        <F as FnOnce<A>>::Output: Future,
+    {
+        type CallFuture<'a> = <F as FnOnce<A>>::Output where Self: 'a;
+
+        extern "rust-call" fn async_call(&self, args: A) -> Self::CallFuture<'_> {
+            self.call(args)
+        }
+    }
+
+    #[unstable(feature = "async_fn_traits", issue = "none")]
+    impl<F: FnMut<A>, A: Tuple> AsyncFnMut<A> for F
+    where
+        <F as FnOnce<A>>::Output: Future,
+    {
+        type CallMutFuture<'a> = <F as FnOnce<A>>::Output where Self: 'a;
+
+        extern "rust-call" fn async_call_mut(&mut self, args: A) -> Self::CallMutFuture<'_> {
+            self.call_mut(args)
+        }
+    }
+
+    #[unstable(feature = "async_fn_traits", issue = "none")]
+    impl<F: FnOnce<A>, A: Tuple> AsyncFnOnce<A> for F
+    where
+        <F as FnOnce<A>>::Output: Future,
+    {
+        type CallOnceFuture = <F as FnOnce<A>>::Output;
+
+        type Output = <<F as FnOnce<A>>::Output as Future>::Output;
+
+        extern "rust-call" fn async_call_once(self, args: A) -> Self::CallOnceFuture {
+            self.call_once(args)
+        }
+    }
+}
diff --git a/library/core/src/ops/mod.rs b/library/core/src/ops/mod.rs
index 35654d0b853..4289a86f89b 100644
--- a/library/core/src/ops/mod.rs
+++ b/library/core/src/ops/mod.rs
@@ -139,6 +139,7 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 mod arith;
+mod async_function;
 mod bit;
 mod control_flow;
 mod coroutine;
@@ -173,6 +174,9 @@ pub use self::drop::Drop;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::function::{Fn, FnMut, FnOnce};
 
+#[unstable(feature = "async_fn_traits", issue = "none")]
+pub use self::async_function::{AsyncFn, AsyncFnMut, AsyncFnOnce};
+
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::index::{Index, IndexMut};
 
diff --git a/library/std/src/os/mod.rs b/library/std/src/os/mod.rs
index 6e11b92b618..f03e0790305 100644
--- a/library/std/src/os/mod.rs
+++ b/library/std/src/os/mod.rs
@@ -85,6 +85,9 @@ pub mod linux;
 #[cfg(any(target_os = "wasi", doc))]
 pub mod wasi;
 
+#[cfg(any(all(target_os = "wasi", target_env = "preview2"), doc))]
+pub mod wasi_preview2;
+
 // windows
 #[cfg(not(all(
     doc,
diff --git a/library/std/src/os/wasi/mod.rs b/library/std/src/os/wasi/mod.rs
index bbaf328f457..05c8d30073f 100644
--- a/library/std/src/os/wasi/mod.rs
+++ b/library/std/src/os/wasi/mod.rs
@@ -28,7 +28,8 @@
 //! [`OsStr`]: crate::ffi::OsStr
 //! [`OsString`]: crate::ffi::OsString
 
-#![stable(feature = "rust1", since = "1.0.0")]
+#![cfg_attr(not(target_env = "preview2"), stable(feature = "rust1", since = "1.0.0"))]
+#![cfg_attr(target_env = "preview2", unstable(feature = "wasm_preview2", issue = "none"))]
 #![deny(unsafe_op_in_unsafe_fn)]
 #![doc(cfg(target_os = "wasi"))]
 
diff --git a/library/std/src/os/wasi_preview2/mod.rs b/library/std/src/os/wasi_preview2/mod.rs
new file mode 100644
index 00000000000..1d44dd72814
--- /dev/null
+++ b/library/std/src/os/wasi_preview2/mod.rs
@@ -0,0 +1,5 @@
+//! Platform-specific extensions to `std` for Preview 2 of the WebAssembly System Interface (WASI).
+//!
+//! This module is currently empty, but will be filled over time as wasi-libc support for WASI Preview 2 is stabilized.
+
+#![stable(feature = "raw_ext", since = "1.1.0")]
diff --git a/library/std/src/sys/pal/mod.rs b/library/std/src/sys/pal/mod.rs
index 041b7c35582..f927d88d46c 100644
--- a/library/std/src/sys/pal/mod.rs
+++ b/library/std/src/sys/pal/mod.rs
@@ -40,6 +40,9 @@ cfg_if::cfg_if! {
     } else if #[cfg(target_os = "wasi")] {
         mod wasi;
         pub use self::wasi::*;
+    } else if #[cfg(all(target_os = "wasi", target_env = "preview2"))] {
+        mod wasi_preview2;
+        pub use self::wasi_preview2::*;
     } else if #[cfg(target_family = "wasm")] {
         mod wasm;
         pub use self::wasm::*;
diff --git a/library/std/src/sys/pal/wasi/helpers.rs b/library/std/src/sys/pal/wasi/helpers.rs
new file mode 100644
index 00000000000..82149cef8fa
--- /dev/null
+++ b/library/std/src/sys/pal/wasi/helpers.rs
@@ -0,0 +1,123 @@
+use crate::io as std_io;
+use crate::mem;
+
+#[inline]
+pub fn is_interrupted(errno: i32) -> bool {
+    errno == wasi::ERRNO_INTR.raw().into()
+}
+
+pub fn decode_error_kind(errno: i32) -> std_io::ErrorKind {
+    use std_io::ErrorKind;
+
+    let Ok(errno) = u16::try_from(errno) else {
+        return ErrorKind::Uncategorized;
+    };
+
+    macro_rules! match_errno {
+        ($($($errno:ident)|+ => $errkind:ident),*, _ => $wildcard:ident $(,)?) => {
+            match errno {
+                $(e if $(e == ::wasi::$errno.raw())||+ => ErrorKind::$errkind),*,
+                _ => ErrorKind::$wildcard,
+            }
+        };
+    }
+
+    match_errno! {
+        ERRNO_2BIG           => ArgumentListTooLong,
+        ERRNO_ACCES          => PermissionDenied,
+        ERRNO_ADDRINUSE      => AddrInUse,
+        ERRNO_ADDRNOTAVAIL   => AddrNotAvailable,
+        ERRNO_AFNOSUPPORT    => Unsupported,
+        ERRNO_AGAIN          => WouldBlock,
+        //    ALREADY        => "connection already in progress",
+        //    BADF           => "bad file descriptor",
+        //    BADMSG         => "bad message",
+        ERRNO_BUSY           => ResourceBusy,
+        //    CANCELED       => "operation canceled",
+        //    CHILD          => "no child processes",
+        ERRNO_CONNABORTED    => ConnectionAborted,
+        ERRNO_CONNREFUSED    => ConnectionRefused,
+        ERRNO_CONNRESET      => ConnectionReset,
+        ERRNO_DEADLK         => Deadlock,
+        //    DESTADDRREQ    => "destination address required",
+        ERRNO_DOM            => InvalidInput,
+        //    DQUOT          => /* reserved */,
+        ERRNO_EXIST          => AlreadyExists,
+        //    FAULT          => "bad address",
+        ERRNO_FBIG           => FileTooLarge,
+        ERRNO_HOSTUNREACH    => HostUnreachable,
+        //    IDRM           => "identifier removed",
+        //    ILSEQ          => "illegal byte sequence",
+        //    INPROGRESS     => "operation in progress",
+        ERRNO_INTR           => Interrupted,
+        ERRNO_INVAL          => InvalidInput,
+        ERRNO_IO             => Uncategorized,
+        //    ISCONN         => "socket is connected",
+        ERRNO_ISDIR          => IsADirectory,
+        ERRNO_LOOP           => FilesystemLoop,
+        //    MFILE          => "file descriptor value too large",
+        ERRNO_MLINK          => TooManyLinks,
+        //    MSGSIZE        => "message too large",
+        //    MULTIHOP       => /* reserved */,
+        ERRNO_NAMETOOLONG    => InvalidFilename,
+        ERRNO_NETDOWN        => NetworkDown,
+        //    NETRESET       => "connection aborted by network",
+        ERRNO_NETUNREACH     => NetworkUnreachable,
+        //    NFILE          => "too many files open in system",
+        //    NOBUFS         => "no buffer space available",
+        ERRNO_NODEV          => NotFound,
+        ERRNO_NOENT          => NotFound,
+        //    NOEXEC         => "executable file format error",
+        //    NOLCK          => "no locks available",
+        //    NOLINK         => /* reserved */,
+        ERRNO_NOMEM          => OutOfMemory,
+        //    NOMSG          => "no message of the desired type",
+        //    NOPROTOOPT     => "protocol not available",
+        ERRNO_NOSPC          => StorageFull,
+        ERRNO_NOSYS          => Unsupported,
+        ERRNO_NOTCONN        => NotConnected,
+        ERRNO_NOTDIR         => NotADirectory,
+        ERRNO_NOTEMPTY       => DirectoryNotEmpty,
+        //    NOTRECOVERABLE => "state not recoverable",
+        //    NOTSOCK        => "not a socket",
+        ERRNO_NOTSUP         => Unsupported,
+        //    NOTTY          => "inappropriate I/O control operation",
+        ERRNO_NXIO           => NotFound,
+        //    OVERFLOW       => "value too large to be stored in data type",
+        //    OWNERDEAD      => "previous owner died",
+        ERRNO_PERM           => PermissionDenied,
+        ERRNO_PIPE           => BrokenPipe,
+        //    PROTO          => "protocol error",
+        ERRNO_PROTONOSUPPORT => Unsupported,
+        //    PROTOTYPE      => "protocol wrong type for socket",
+        //    RANGE          => "result too large",
+        ERRNO_ROFS           => ReadOnlyFilesystem,
+        ERRNO_SPIPE          => NotSeekable,
+        ERRNO_SRCH           => NotFound,
+        //    STALE          => /* reserved */,
+        ERRNO_TIMEDOUT       => TimedOut,
+        ERRNO_TXTBSY         => ResourceBusy,
+        ERRNO_XDEV           => CrossesDevices,
+        ERRNO_NOTCAPABLE     => PermissionDenied,
+        _                    => Uncategorized,
+    }
+}
+
+pub fn abort_internal() -> ! {
+    unsafe { libc::abort() }
+}
+
+pub fn hashmap_random_keys() -> (u64, u64) {
+    let mut ret = (0u64, 0u64);
+    unsafe {
+        let base = &mut ret as *mut (u64, u64) as *mut u8;
+        let len = mem::size_of_val(&ret);
+        wasi::random_get(base, len).expect("random_get failure");
+    }
+    return ret;
+}
+
+#[inline]
+pub(crate) fn err2io(err: wasi::Errno) -> std_io::Error {
+    std_io::Error::from_raw_os_error(err.raw().into())
+}
diff --git a/library/std/src/sys/pal/wasi/mod.rs b/library/std/src/sys/pal/wasi/mod.rs
index 4ffc8ecdd67..a4b55093bf4 100644
--- a/library/std/src/sys/pal/wasi/mod.rs
+++ b/library/std/src/sys/pal/wasi/mod.rs
@@ -14,9 +14,6 @@
 //! compiling for wasm. That way it's a compile time error for something that's
 //! guaranteed to be a runtime error!
 
-use crate::io as std_io;
-use crate::mem;
-
 #[path = "../unix/alloc.rs"]
 pub mod alloc;
 pub mod args;
@@ -72,123 +69,12 @@ cfg_if::cfg_if! {
 mod common;
 pub use common::*;
 
-#[inline]
-pub fn is_interrupted(errno: i32) -> bool {
-    errno == wasi::ERRNO_INTR.raw().into()
-}
-
-pub fn decode_error_kind(errno: i32) -> std_io::ErrorKind {
-    use std_io::ErrorKind;
-
-    let Ok(errno) = u16::try_from(errno) else {
-        return ErrorKind::Uncategorized;
-    };
-
-    macro_rules! match_errno {
-        ($($($errno:ident)|+ => $errkind:ident),*, _ => $wildcard:ident $(,)?) => {
-            match errno {
-                $(e if $(e == ::wasi::$errno.raw())||+ => ErrorKind::$errkind),*,
-                _ => ErrorKind::$wildcard,
-            }
-        };
-    }
-
-    match_errno! {
-        ERRNO_2BIG           => ArgumentListTooLong,
-        ERRNO_ACCES          => PermissionDenied,
-        ERRNO_ADDRINUSE      => AddrInUse,
-        ERRNO_ADDRNOTAVAIL   => AddrNotAvailable,
-        ERRNO_AFNOSUPPORT    => Unsupported,
-        ERRNO_AGAIN          => WouldBlock,
-        //    ALREADY        => "connection already in progress",
-        //    BADF           => "bad file descriptor",
-        //    BADMSG         => "bad message",
-        ERRNO_BUSY           => ResourceBusy,
-        //    CANCELED       => "operation canceled",
-        //    CHILD          => "no child processes",
-        ERRNO_CONNABORTED    => ConnectionAborted,
-        ERRNO_CONNREFUSED    => ConnectionRefused,
-        ERRNO_CONNRESET      => ConnectionReset,
-        ERRNO_DEADLK         => Deadlock,
-        //    DESTADDRREQ    => "destination address required",
-        ERRNO_DOM            => InvalidInput,
-        //    DQUOT          => /* reserved */,
-        ERRNO_EXIST          => AlreadyExists,
-        //    FAULT          => "bad address",
-        ERRNO_FBIG           => FileTooLarge,
-        ERRNO_HOSTUNREACH    => HostUnreachable,
-        //    IDRM           => "identifier removed",
-        //    ILSEQ          => "illegal byte sequence",
-        //    INPROGRESS     => "operation in progress",
-        ERRNO_INTR           => Interrupted,
-        ERRNO_INVAL          => InvalidInput,
-        ERRNO_IO             => Uncategorized,
-        //    ISCONN         => "socket is connected",
-        ERRNO_ISDIR          => IsADirectory,
-        ERRNO_LOOP           => FilesystemLoop,
-        //    MFILE          => "file descriptor value too large",
-        ERRNO_MLINK          => TooManyLinks,
-        //    MSGSIZE        => "message too large",
-        //    MULTIHOP       => /* reserved */,
-        ERRNO_NAMETOOLONG    => InvalidFilename,
-        ERRNO_NETDOWN        => NetworkDown,
-        //    NETRESET       => "connection aborted by network",
-        ERRNO_NETUNREACH     => NetworkUnreachable,
-        //    NFILE          => "too many files open in system",
-        //    NOBUFS         => "no buffer space available",
-        ERRNO_NODEV          => NotFound,
-        ERRNO_NOENT          => NotFound,
-        //    NOEXEC         => "executable file format error",
-        //    NOLCK          => "no locks available",
-        //    NOLINK         => /* reserved */,
-        ERRNO_NOMEM          => OutOfMemory,
-        //    NOMSG          => "no message of the desired type",
-        //    NOPROTOOPT     => "protocol not available",
-        ERRNO_NOSPC          => StorageFull,
-        ERRNO_NOSYS          => Unsupported,
-        ERRNO_NOTCONN        => NotConnected,
-        ERRNO_NOTDIR         => NotADirectory,
-        ERRNO_NOTEMPTY       => DirectoryNotEmpty,
-        //    NOTRECOVERABLE => "state not recoverable",
-        //    NOTSOCK        => "not a socket",
-        ERRNO_NOTSUP         => Unsupported,
-        //    NOTTY          => "inappropriate I/O control operation",
-        ERRNO_NXIO           => NotFound,
-        //    OVERFLOW       => "value too large to be stored in data type",
-        //    OWNERDEAD      => "previous owner died",
-        ERRNO_PERM           => PermissionDenied,
-        ERRNO_PIPE           => BrokenPipe,
-        //    PROTO          => "protocol error",
-        ERRNO_PROTONOSUPPORT => Unsupported,
-        //    PROTOTYPE      => "protocol wrong type for socket",
-        //    RANGE          => "result too large",
-        ERRNO_ROFS           => ReadOnlyFilesystem,
-        ERRNO_SPIPE          => NotSeekable,
-        ERRNO_SRCH           => NotFound,
-        //    STALE          => /* reserved */,
-        ERRNO_TIMEDOUT       => TimedOut,
-        ERRNO_TXTBSY         => ResourceBusy,
-        ERRNO_XDEV           => CrossesDevices,
-        ERRNO_NOTCAPABLE     => PermissionDenied,
-        _                    => Uncategorized,
-    }
-}
-
-pub fn abort_internal() -> ! {
-    unsafe { libc::abort() }
-}
-
-pub fn hashmap_random_keys() -> (u64, u64) {
-    let mut ret = (0u64, 0u64);
-    unsafe {
-        let base = &mut ret as *mut (u64, u64) as *mut u8;
-        let len = mem::size_of_val(&ret);
-        wasi::random_get(base, len).expect("random_get failure");
-    }
-    return ret;
-}
-
-#[inline]
-fn err2io(err: wasi::Errno) -> std_io::Error {
-    std_io::Error::from_raw_os_error(err.raw().into())
-}
+mod helpers;
+// These exports are listed individually to work around Rust's glob import
+// conflict rules. If we glob export `helpers` and `common` together, then
+// the compiler complains about conflicts.
+pub use helpers::abort_internal;
+pub use helpers::decode_error_kind;
+use helpers::err2io;
+pub use helpers::hashmap_random_keys;
+pub use helpers::is_interrupted;
diff --git a/library/std/src/sys/pal/wasi_preview2/mod.rs b/library/std/src/sys/pal/wasi_preview2/mod.rs
new file mode 100644
index 00000000000..b61695015bb
--- /dev/null
+++ b/library/std/src/sys/pal/wasi_preview2/mod.rs
@@ -0,0 +1,78 @@
+//! System bindings for the wasi preview 2 target.
+//!
+//! This is the next evolution of the original wasi target, and is intended to
+//! replace that target over time.
+//!
+//! To begin with, this target mirrors the wasi target 1 to 1, but over
+//! time this will change significantly.
+
+#[path = "../unix/alloc.rs"]
+pub mod alloc;
+#[path = "../wasi/args.rs"]
+pub mod args;
+#[path = "../unix/cmath.rs"]
+pub mod cmath;
+#[path = "../wasi/env.rs"]
+pub mod env;
+#[path = "../wasi/fd.rs"]
+pub mod fd;
+#[path = "../wasi/fs.rs"]
+pub mod fs;
+#[allow(unused)]
+#[path = "../wasm/atomics/futex.rs"]
+pub mod futex;
+#[path = "../wasi/io.rs"]
+pub mod io;
+
+#[path = "../wasi/net.rs"]
+pub mod net;
+#[path = "../wasi/os.rs"]
+pub mod os;
+#[path = "../unix/os_str.rs"]
+pub mod os_str;
+#[path = "../unix/path.rs"]
+pub mod path;
+#[path = "../unsupported/pipe.rs"]
+pub mod pipe;
+#[path = "../unsupported/process.rs"]
+pub mod process;
+#[path = "../wasi/stdio.rs"]
+pub mod stdio;
+#[path = "../wasi/thread.rs"]
+pub mod thread;
+#[path = "../unsupported/thread_local_dtor.rs"]
+pub mod thread_local_dtor;
+#[path = "../unsupported/thread_local_key.rs"]
+pub mod thread_local_key;
+#[path = "../wasi/time.rs"]
+pub mod time;
+
+cfg_if::cfg_if! {
+    if #[cfg(target_feature = "atomics")] {
+        compile_error!("The wasm32-wasi-preview2 target does not support atomics");
+    } else {
+        #[path = "../unsupported/locks/mod.rs"]
+        pub mod locks;
+        #[path = "../unsupported/once.rs"]
+        pub mod once;
+        #[path = "../unsupported/thread_parking.rs"]
+        pub mod thread_parking;
+    }
+}
+
+#[path = "../unsupported/common.rs"]
+#[deny(unsafe_op_in_unsafe_fn)]
+#[allow(unused)]
+mod common;
+pub use common::*;
+
+#[path = "../wasi/helpers.rs"]
+mod helpers;
+// These exports are listed individually to work around Rust's glob import
+// conflict rules. If we glob export `helpers` and `common` together, then
+// the compiler complains about conflicts.
+pub use helpers::abort_internal;
+pub use helpers::decode_error_kind;
+use helpers::err2io;
+pub use helpers::hashmap_random_keys;
+pub use helpers::is_interrupted;
diff --git a/src/bootstrap/src/core/build_steps/compile.rs b/src/bootstrap/src/core/build_steps/compile.rs
index f954f01fe4e..e06bc3fb09a 100644
--- a/src/bootstrap/src/core/build_steps/compile.rs
+++ b/src/bootstrap/src/core/build_steps/compile.rs
@@ -367,10 +367,13 @@ fn copy_self_contained_objects(
         let srcdir = builder
             .wasi_root(target)
             .unwrap_or_else(|| {
-                panic!("Target {:?} does not have a \"wasi-root\" key", target.triple)
+                panic!(
+                    "Target {:?} does not have a \"wasi-root\" key in Config.toml",
+                    target.triple
+                )
             })
             .join("lib")
-            .join(target.to_string().replace("-preview1", ""));
+            .join(target.to_string().replace("-preview1", "").replace("-preview2", ""));
         for &obj in &["libc.a", "crt1-command.o", "crt1-reactor.o"] {
             copy_and_stamp(
                 builder,
diff --git a/src/bootstrap/src/lib.rs b/src/bootstrap/src/lib.rs
index 1336abf6c7a..1726e7aacbc 100644
--- a/src/bootstrap/src/lib.rs
+++ b/src/bootstrap/src/lib.rs
@@ -88,7 +88,7 @@ const EXTRA_CHECK_CFGS: &[(Option<Mode>, &str, Option<&[&'static str]>)] = &[
     (Some(Mode::Std), "no_sync", None),
     (Some(Mode::Std), "backtrace_in_libstd", None),
     /* Extra values not defined in the built-in targets yet, but used in std */
-    (Some(Mode::Std), "target_env", Some(&["libnx"])),
+    (Some(Mode::Std), "target_env", Some(&["libnx", "preview2"])),
     // (Some(Mode::Std), "target_os", Some(&[])),
     // #[cfg(bootstrap)] zkvm
     (Some(Mode::Std), "target_os", Some(&["zkvm"])),
diff --git a/src/doc/rustc/src/SUMMARY.md b/src/doc/rustc/src/SUMMARY.md
index 1998b008dc8..990998ea704 100644
--- a/src/doc/rustc/src/SUMMARY.md
+++ b/src/doc/rustc/src/SUMMARY.md
@@ -59,6 +59,7 @@
     - [*-unknown-openbsd](platform-support/openbsd.md)
     - [\*-unknown-uefi](platform-support/unknown-uefi.md)
     - [wasm32-wasi-preview1-threads](platform-support/wasm32-wasi-preview1-threads.md)
+    - [wasm32-wasi-preview2](platform-support/wasm32-wasi-preview2.md)
     - [wasm64-unknown-unknown](platform-support/wasm64-unknown-unknown.md)
     - [\*-win7-windows-msvc](platform-support/win7-windows-msvc.md)
     - [x86_64-fortanix-unknown-sgx](platform-support/x86_64-fortanix-unknown-sgx.md)
diff --git a/src/doc/rustc/src/platform-support.md b/src/doc/rustc/src/platform-support.md
index f648a60b6c4..fb751b7229e 100644
--- a/src/doc/rustc/src/platform-support.md
+++ b/src/doc/rustc/src/platform-support.md
@@ -360,6 +360,7 @@ target | std | host | notes
 `thumbv7a-pc-windows-msvc` | ? |  |
 `thumbv7a-uwp-windows-msvc` | ✓ |  |
 `thumbv7neon-unknown-linux-musleabihf` | ? |  | Thumb2-mode ARMv7-A Linux with NEON, MUSL
+[`wasm32-wasi-preview2`](platform-support/wasm32-wasi-preview2.md) | ✓ |  | WebAssembly
 [`wasm64-unknown-unknown`](platform-support/wasm64-unknown-unknown.md) | ? |  | WebAssembly
 `x86_64-apple-ios-macabi` | ✓ |  | Apple Catalyst on x86_64
 [`x86_64-apple-tvos`](platform-support/apple-tvos.md) | ? |  | x86 64-bit tvOS
diff --git a/src/doc/rustc/src/platform-support/wasm32-wasi-preview2.md b/src/doc/rustc/src/platform-support/wasm32-wasi-preview2.md
new file mode 100644
index 00000000000..837efd13d41
--- /dev/null
+++ b/src/doc/rustc/src/platform-support/wasm32-wasi-preview2.md
@@ -0,0 +1,30 @@
+# `wasm32-wasi-preview2`
+
+**Tier: 3**
+
+The `wasm32-wasi-preview2` target is a new and still (as of January 2024) an
+experimental target. This target is an extension to `wasm32-wasi-preview1` target,
+originally known as `wasm32-wasi`. It is the next evolution in the development of
+wasi (the [WebAssembly System Interface](https://wasi.dev)) that uses the WebAssembly
+[component model] to allow for a standardized set of syscalls that are intended to empower
+WebAssembly binaries with native host capabilities.
+
+[component model]: https://github.com/WebAssembly/component-model
+
+## Target maintainers
+
+- Alex Crichton, https://github.com/alexcrichton
+- Ryan Levick, https://github.com/rylev
+
+## Requirements
+
+This target is cross-compiled. The target supports `std` fully.
+
+## Platform requirements
+
+The WebAssembly runtime should support the wasi preview 2 API set.
+
+This target is not a stable target. This means that there are only a few engines
+which implement wasi preview 2, for example:
+
+* Wasmtime - `-W component-model`
diff --git a/src/doc/style-guide/src/editions.md b/src/doc/style-guide/src/editions.md
index 19e62c4867c..b9a89c20cee 100644
--- a/src/doc/style-guide/src/editions.md
+++ b/src/doc/style-guide/src/editions.md
@@ -36,6 +36,10 @@ For a full history of changes in the Rust 2024 style edition, see the git
 history of the style guide. Notable changes in the Rust 2024 style edition
 include:
 
+- [#114764](https://github.com/rust-lang/rust/pull/114764) As the last member
+  of a delimited expression, delimited expressions are generally combinable,
+  regardless of the number of members. Previously only applied with exactly
+  one member (except for closures with explicit blocks).
 - Miscellaneous `rustfmt` bugfixes.
 - Use version-sort (sort `x8`, `x16`, `x32`, `x64`, `x128` in that order).
 - Change "ASCIIbetical" sort to Unicode-aware "non-lowercase before lowercase".
diff --git a/src/doc/style-guide/src/expressions.md b/src/doc/style-guide/src/expressions.md
index 12037b5992e..171a24cd89d 100644
--- a/src/doc/style-guide/src/expressions.md
+++ b/src/doc/style-guide/src/expressions.md
@@ -818,11 +818,11 @@ E.g., `&&Some(foo)` matches, `Foo(4, Bar)` does not.
 
 ## Combinable expressions
 
-Where a function call has a single argument, and that argument is formatted
-across multiple-lines, format the outer call as if it were a single-line call,
+When the last argument in a function call is formatted across
+multiple-lines, format the outer call as if it were a single-line call,
 if the result fits. Apply the same combining behaviour to any similar
 expressions which have multi-line, block-indented lists of sub-expressions
-delimited by parentheses (e.g., macros or tuple struct literals). E.g.,
+delimited by parentheses, brackets, or braces. E.g.,
 
 ```rust
 foo(bar(
@@ -848,20 +848,61 @@ let arr = [combinable(
     an_expr,
     another_expr,
 )];
+
+let x = Thing(an_expr, another_expr, match cond {
+    A => 1,
+    B => 2,
+});
+
+let x = format!("Stuff: {}", [
+    an_expr,
+    another_expr,
+]);
+
+let x = func(an_expr, another_expr, SomeStruct {
+    field: this_is_long,
+    another_field: 123,
+});
 ```
 
 Apply this behavior recursively.
 
-For a function with multiple arguments, if the last argument is a multi-line
-closure with an explicit block, there are no other closure arguments, and all
-the arguments and the first line of the closure fit on the first line, use the
-same combining behavior:
+If the last argument is a multi-line closure with an explicit block,
+only apply the combining behavior if there are no other closure arguments.
 
 ```rust
+// Combinable
 foo(first_arg, x, |param| {
     action();
     foo(param)
 })
+// Not combinable, because the closure is not the last argument
+foo(
+    first_arg,
+    |param| {
+        action();
+        foo(param)
+    },
+    whatever,
+)
+// Not combinable, because the first line of the closure does not fit
+foo(
+    first_arg,
+    x,
+    move |very_long_param_causing_line_to_overflow| -> Bar {
+        action();
+        foo(param)
+    },
+)
+// Not combinable, because there is more than one closure argument
+foo(
+    first_arg,
+    |x| x.bar(),
+    |param| {
+        action();
+        foo(param)
+    },
+)
 ```
 
 ## Ranges
diff --git a/src/tools/clippy/tests/ui/modulo_one.rs b/src/tools/clippy/tests/ui/modulo_one.rs
index c1dbe9d9a87..c332a15f157 100644
--- a/src/tools/clippy/tests/ui/modulo_one.rs
+++ b/src/tools/clippy/tests/ui/modulo_one.rs
@@ -33,7 +33,6 @@ fn main() {
     INT_MIN % NEG_ONE;
     //~^ ERROR: this operation will panic at runtime
     //~| ERROR: any number modulo -1 will panic/overflow or result in 0
-    // ONLY caught by rustc
+    // Not caught by lint, we don't look into static items, even if entirely immutable.
     INT_MIN % STATIC_NEG_ONE;
-    //~^ ERROR: this operation will panic at runtime
 }
diff --git a/src/tools/clippy/tests/ui/modulo_one.stderr b/src/tools/clippy/tests/ui/modulo_one.stderr
index cc211ab6cd3..06bbb0f5d9a 100644
--- a/src/tools/clippy/tests/ui/modulo_one.stderr
+++ b/src/tools/clippy/tests/ui/modulo_one.stderr
@@ -12,12 +12,6 @@ error: this operation will panic at runtime
 LL |     INT_MIN % NEG_ONE;
    |     ^^^^^^^^^^^^^^^^^ attempt to compute `i64::MIN % -1_i64`, which would overflow
 
-error: this operation will panic at runtime
-  --> $DIR/modulo_one.rs:37:5
-   |
-LL |     INT_MIN % STATIC_NEG_ONE;
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^ attempt to compute `i64::MIN % -1_i64`, which would overflow
-
 error: any number modulo 1 will be 0
   --> $DIR/modulo_one.rs:8:5
    |
@@ -57,5 +51,5 @@ error: any number modulo -1 will panic/overflow or result in 0
 LL |     INT_MIN % NEG_ONE;
    |     ^^^^^^^^^^^^^^^^^
 
-error: aborting due to 9 previous errors
+error: aborting due to 8 previous errors
 
diff --git a/src/tools/compiletest/src/header.rs b/src/tools/compiletest/src/header.rs
index e70e01e8757..ff907152ca9 100644
--- a/src/tools/compiletest/src/header.rs
+++ b/src/tools/compiletest/src/header.rs
@@ -1109,9 +1109,6 @@ fn ignore_lldb(config: &Config, line: &str) -> IgnoreDecision {
 }
 
 fn ignore_llvm(config: &Config, line: &str) -> IgnoreDecision {
-    if config.system_llvm && line.starts_with("no-system-llvm") {
-        return IgnoreDecision::Ignore { reason: "ignored when the system LLVM is used".into() };
-    }
     if let Some(needed_components) =
         config.parse_name_value_directive(line, "needs-llvm-components")
     {
diff --git a/src/tools/compiletest/src/header/tests.rs b/src/tools/compiletest/src/header/tests.rs
index 8882f1582ac..c859e8acade 100644
--- a/src/tools/compiletest/src/header/tests.rs
+++ b/src/tools/compiletest/src/header/tests.rs
@@ -243,15 +243,6 @@ fn aux_build() {
 }
 
 #[test]
-fn no_system_llvm() {
-    let config: Config = cfg().system_llvm(false).build();
-    assert!(!check_ignore(&config, "// no-system-llvm"));
-
-    let config: Config = cfg().system_llvm(true).build();
-    assert!(check_ignore(&config, "// no-system-llvm"));
-}
-
-#[test]
 fn llvm_version() {
     let config: Config = cfg().llvm_version("8.1.2").build();
     assert!(check_ignore(&config, "// min-llvm-version: 9.0"));
@@ -267,6 +258,18 @@ fn llvm_version() {
 }
 
 #[test]
+fn system_llvm_version() {
+    let config: Config = cfg().system_llvm(true).llvm_version("17.0.0").build();
+    assert!(check_ignore(&config, "// min-system-llvm-version: 18.0"));
+
+    let config: Config = cfg().system_llvm(true).llvm_version("18.0.0").build();
+    assert!(!check_ignore(&config, "// min-system-llvm-version: 18.0"));
+
+    let config: Config = cfg().llvm_version("17.0.0").build();
+    assert!(!check_ignore(&config, "// min-system-llvm-version: 18.0"));
+}
+
+#[test]
 fn ignore_target() {
     let config: Config = cfg().target("x86_64-unknown-linux-gnu").build();
 
diff --git a/src/tools/miri/src/shims/intrinsics/mod.rs b/src/tools/miri/src/shims/intrinsics/mod.rs
index a1db7bf74f2..8edc0a4220d 100644
--- a/src/tools/miri/src/shims/intrinsics/mod.rs
+++ b/src/tools/miri/src/shims/intrinsics/mod.rs
@@ -5,6 +5,7 @@ use std::iter;
 
 use log::trace;
 
+use rand::Rng;
 use rustc_apfloat::{Float, Round};
 use rustc_middle::ty::layout::LayoutOf;
 use rustc_middle::{
@@ -141,6 +142,17 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
                 this.write_pointer(Pointer::new(ptr.provenance, masked_addr), dest)?;
             }
 
+            // We want to return either `true` or `false` at random, or else something like
+            // ```
+            // if !is_val_statically_known(0) { unreachable_unchecked(); }
+            // ```
+            // Would not be considered UB, or the other way around (`is_val_statically_known(0)`).
+            "is_val_statically_known" => {
+                let [_] = check_arg_count(args)?;
+                let branch: bool = this.machine.rng.get_mut().gen();
+                this.write_scalar(Scalar::from_bool(branch), dest)?;
+            }
+
             // Floating-point operations
             "fabsf32" => {
                 let [f] = check_arg_count(args)?;
diff --git a/src/tools/miri/tests/pass/intrinsics.rs b/src/tools/miri/tests/pass/intrinsics.rs
index 8c6eeab2219..8e46bd7ad48 100644
--- a/src/tools/miri/tests/pass/intrinsics.rs
+++ b/src/tools/miri/tests/pass/intrinsics.rs
@@ -33,6 +33,21 @@ fn main() {
     assert_eq!(intrinsics::likely(false), false);
     assert_eq!(intrinsics::unlikely(true), true);
 
+    let mut saw_true = false;
+    let mut saw_false = false;
+
+    for _ in 0..50 {
+        if unsafe { intrinsics::is_val_statically_known(0) } {
+            saw_true = true;
+        } else {
+            saw_false = true;
+        }
+    }
+    assert!(
+        saw_true && saw_false,
+        "`is_val_statically_known` failed to return both true and false. Congrats, you won the lottery!"
+    );
+
     intrinsics::forget(Bomb);
 
     let _v = intrinsics::discriminant_value(&Some(()));
diff --git a/tests/assembly/targets/targets-elf.rs b/tests/assembly/targets/targets-elf.rs
index 6eec05e85ac..f6f2f5e88ff 100644
--- a/tests/assembly/targets/targets-elf.rs
+++ b/tests/assembly/targets/targets-elf.rs
@@ -534,6 +534,9 @@
 // revisions: wasm64_unknown_unknown
 // [wasm64_unknown_unknown] compile-flags: --target wasm64-unknown-unknown
 // [wasm64_unknown_unknown] needs-llvm-components: webassembly
+// revisions: wasm32_wasi_preview2
+// [wasm32_wasi_preview2] compile-flags: --target wasm32-wasi-preview2
+// [wasm32_wasi_preview2] needs-llvm-components: webassembly
 // revisions: x86_64_apple_darwin
 // [x86_64_apple_darwin] compile-flags: --target x86_64-apple-darwin
 // [x86_64_apple_darwin] needs-llvm-components: x86
diff --git a/tests/codegen/alloc-optimisation.rs b/tests/codegen/alloc-optimisation.rs
index f88d695d87e..900eb687a45 100644
--- a/tests/codegen/alloc-optimisation.rs
+++ b/tests/codegen/alloc-optimisation.rs
@@ -1,5 +1,3 @@
-//
-// no-system-llvm
 // compile-flags: -O
 #![crate_type = "lib"]
 
diff --git a/tests/codegen/array-map.rs b/tests/codegen/array-map.rs
index 4d218e6a951..9846cc7f5c8 100644
--- a/tests/codegen/array-map.rs
+++ b/tests/codegen/array-map.rs
@@ -1,5 +1,4 @@
 // compile-flags: -C opt-level=3 -C target-cpu=x86-64-v3
-// no-system-llvm
 // only-x86_64
 // ignore-debug (the extra assertions get in the way)
 
@@ -10,7 +9,7 @@
 pub fn short_integer_map(x: [u32; 8]) -> [u32; 8] {
     // CHECK: load <8 x i32>
     // CHECK: shl <8 x i32>
-    // CHECK: or <8 x i32>
+    // CHECK: or{{( disjoint)?}} <8 x i32>
     // CHECK: store <8 x i32>
     x.map(|x| 2 * x + 1)
 }
diff --git a/tests/codegen/dealloc-no-unwind.rs b/tests/codegen/dealloc-no-unwind.rs
index 3812ef44ff2..c2656908f16 100644
--- a/tests/codegen/dealloc-no-unwind.rs
+++ b/tests/codegen/dealloc-no-unwind.rs
@@ -1,4 +1,3 @@
-// no-system-llvm
 // compile-flags: -O
 
 #![crate_type="lib"]
diff --git a/tests/codegen/fewer-names.rs b/tests/codegen/fewer-names.rs
index df1080bff2b..05643fab96a 100644
--- a/tests/codegen/fewer-names.rs
+++ b/tests/codegen/fewer-names.rs
@@ -1,4 +1,3 @@
-// no-system-llvm
 // compile-flags: -Coverflow-checks=no -O
 // revisions: YES NO
 // [YES]compile-flags: -Zfewer-names=yes
diff --git a/tests/codegen/integer-overflow.rs b/tests/codegen/integer-overflow.rs
index 183de56db96..b5c351b5e35 100644
--- a/tests/codegen/integer-overflow.rs
+++ b/tests/codegen/integer-overflow.rs
@@ -1,4 +1,3 @@
-// no-system-llvm
 // compile-flags: -O -C overflow-checks=on
 
 #![crate_type = "lib"]
diff --git a/tests/codegen/is_val_statically_known.rs b/tests/codegen/is_val_statically_known.rs
new file mode 100644
index 00000000000..44187d4f667
--- /dev/null
+++ b/tests/codegen/is_val_statically_known.rs
@@ -0,0 +1,48 @@
+// compile-flags: --crate-type=lib -Zmerge-functions=disabled -O
+
+#![feature(core_intrinsics)]
+
+use std::intrinsics::is_val_statically_known;
+
+pub struct A(u32);
+pub enum B {
+    Ye(u32),
+}
+
+#[inline]
+pub fn _u32(a: u32) -> i32 {
+    if unsafe { is_val_statically_known(a) } { 1 } else { 0 }
+}
+
+// CHECK-LABEL: @_u32_true(
+#[no_mangle]
+pub fn _u32_true() -> i32 {
+    // CHECK: ret i32 1
+    _u32(1)
+}
+
+// CHECK-LABEL: @_u32_false(
+#[no_mangle]
+pub fn _u32_false(a: u32) -> i32 {
+    // CHECK: ret i32 0
+    _u32(a)
+}
+
+#[inline]
+pub fn _bool(b: bool) -> i32 {
+    if unsafe { is_val_statically_known(b) } { 3 } else { 2 }
+}
+
+// CHECK-LABEL: @_bool_true(
+#[no_mangle]
+pub fn _bool_true() -> i32 {
+    // CHECK: ret i32 3
+    _bool(true)
+}
+
+// CHECK-LABEL: @_bool_false(
+#[no_mangle]
+pub fn _bool_false(b: bool) -> i32 {
+    // CHECK: ret i32 2
+    _bool(b)
+}
diff --git a/tests/codegen/issues/issue-116878.rs b/tests/codegen/issues/issue-116878.rs
index d5f679459f7..5864f532324 100644
--- a/tests/codegen/issues/issue-116878.rs
+++ b/tests/codegen/issues/issue-116878.rs
@@ -1,4 +1,3 @@
-// no-system-llvm
 // compile-flags: -O
 // ignore-debug: the debug assertions get in the way
 #![crate_type = "lib"]
diff --git a/tests/codegen/issues/issue-44056-macos-tls-align.rs b/tests/codegen/issues/issue-44056-macos-tls-align.rs
index 1a3923f1bb1..44aa9766d3c 100644
--- a/tests/codegen/issues/issue-44056-macos-tls-align.rs
+++ b/tests/codegen/issues/issue-44056-macos-tls-align.rs
@@ -1,6 +1,5 @@
 //
 // only-macos
-// no-system-llvm
 // compile-flags: -O
 
 #![crate_type = "rlib"]
diff --git a/tests/codegen/issues/issue-69101-bounds-check.rs b/tests/codegen/issues/issue-69101-bounds-check.rs
index a3aca3a2912..655de45fd51 100644
--- a/tests/codegen/issues/issue-69101-bounds-check.rs
+++ b/tests/codegen/issues/issue-69101-bounds-check.rs
@@ -1,4 +1,3 @@
-// no-system-llvm
 // compile-flags: -O
 // ignore-debug: the debug assertions get in the way
 #![crate_type = "lib"]
diff --git a/tests/codegen/match-optimizes-away.rs b/tests/codegen/match-optimizes-away.rs
index 8f66c518ccf..400606b42d5 100644
--- a/tests/codegen/match-optimizes-away.rs
+++ b/tests/codegen/match-optimizes-away.rs
@@ -1,5 +1,4 @@
 //
-// no-system-llvm
 // compile-flags: -O
 #![crate_type="lib"]
 
diff --git a/tests/codegen/pow_of_two.rs b/tests/codegen/pow_of_two.rs
new file mode 100644
index 00000000000..a8c0550e332
--- /dev/null
+++ b/tests/codegen/pow_of_two.rs
@@ -0,0 +1,55 @@
+// compile-flags: --crate-type=lib -Zmerge-functions=disabled -O -C overflow-checks=false
+
+// CHECK-LABEL: @a(
+#[no_mangle]
+pub fn a(exp: u32) -> u64 {
+    // CHECK: %{{[^ ]+}} = icmp ugt i32 %exp, 64
+    // CHECK: %{{[^ ]+}} = zext i32 %exp to i64
+    // CHECK: %{{[^ ]+}} = shl nuw i64 {{[^ ]+}}, %{{[^ ]+}}
+    // CHECK: ret i64 %{{[^ ]+}}
+    2u64.pow(exp)
+}
+
+// CHECK-LABEL: @b(
+#[no_mangle]
+pub fn b(exp: u32) -> i64 {
+    // CHECK: %{{[^ ]+}} = icmp ugt i32 %exp, 64
+    // CHECK: %{{[^ ]+}} = zext i32 %exp to i64
+    // CHECK: %{{[^ ]+}} = shl nuw i64 {{[^ ]+}}, %{{[^ ]+}}
+    // CHECK: ret i64 %{{[^ ]+}}
+    2i64.pow(exp)
+}
+
+// CHECK-LABEL: @c(
+#[no_mangle]
+pub fn c(exp: u32) -> u32 {
+    // CHECK: %{{[^ ]+}} = icmp ugt i32 %exp, 16
+    // CHECK: %{{[^ ]+}} = shl nuw nsw i32 %exp, 1
+    // CHECK: %{{[^ ]+}} = shl nuw i32 1, %{{[^ ]+}}
+    // CHECK: %{{[^ ]+}} = select i1 %{{[^ ]+}}, i32 0, i32 %{{[^ ]+}}
+    // CHECK: ret i32 %{{[^ ]+}}
+    4u32.pow(exp)
+}
+
+// CHECK-LABEL: @d(
+#[no_mangle]
+pub fn d(exp: u32) -> u32 {
+    // CHECK: %{{[^ ]+}} = icmp ugt i32 %exp, 6
+    // CHECK: %{{[^ ]+}} = mul nuw nsw i32 %exp, 5
+    // CHECK: %{{[^ ]+}} = shl nuw nsw i32 1, %{{[^ ]+}}
+    // CHECK: %{{[^ ]+}} = select i1 {{[^ ]+}}, i32 0, i32 %{{[^ ]+}}
+    // CHECK: ret i32 %{{[^ ]+}}
+    32u32.pow(exp)
+}
+
+// CHECK-LABEL: @e(
+#[no_mangle]
+pub fn e(exp: u32) -> i32 {
+    // CHECK: %{{[^ ]+}} = icmp ugt i32 %exp, 6
+    // CHECK: %{{[^ ]+}} = mul nuw {{(nsw )?}}i32 %exp, 5
+    // CHECK: %{{[^ ]+}} = shl nuw {{(nsw )?}}i32 1, %{{[^ ]+}}
+    // CHECK: %{{[^ ]+}} = select i1 {{[^ ]+}}, i32 0, i32 %{{[^ ]+}}
+    // CHECK: ret i32 %{{[^ ]+}}
+    32i32.pow(exp)
+}
+// note: d and e are expected to yield the same IR
diff --git a/tests/codegen/ptr-read-metadata.rs b/tests/codegen/ptr-read-metadata.rs
index 73d1db6df27..94152ed11ba 100644
--- a/tests/codegen/ptr-read-metadata.rs
+++ b/tests/codegen/ptr-read-metadata.rs
@@ -1,5 +1,4 @@
 // compile-flags: -O -Z merge-functions=disabled
-// no-system-llvm
 // ignore-debug (the extra assertions get in the way)
 
 #![crate_type = "lib"]
diff --git a/tests/codegen/slice-as_chunks.rs b/tests/codegen/slice-as_chunks.rs
index efac9f3d68d..e832f90d07a 100644
--- a/tests/codegen/slice-as_chunks.rs
+++ b/tests/codegen/slice-as_chunks.rs
@@ -1,4 +1,3 @@
-// no-system-llvm
 // compile-flags: -O
 // only-64bit (because the LLVM type of i64 for usize shows up)
 // ignore-debug: the debug assertions get in the way
diff --git a/tests/codegen/slice-iter-len-eq-zero.rs b/tests/codegen/slice-iter-len-eq-zero.rs
index c7515ce35a3..77febf5170d 100644
--- a/tests/codegen/slice-iter-len-eq-zero.rs
+++ b/tests/codegen/slice-iter-len-eq-zero.rs
@@ -1,4 +1,3 @@
-// no-system-llvm
 // compile-flags: -O
 // ignore-debug: the debug assertions add extra comparisons
 #![crate_type = "lib"]
diff --git a/tests/codegen/slice-iter-nonnull.rs b/tests/codegen/slice-iter-nonnull.rs
index 1e691cc34c9..93c8828ccd3 100644
--- a/tests/codegen/slice-iter-nonnull.rs
+++ b/tests/codegen/slice-iter-nonnull.rs
@@ -1,4 +1,3 @@
-// no-system-llvm
 // compile-flags: -O
 // ignore-debug (these add extra checks that make it hard to verify)
 #![crate_type = "lib"]
diff --git a/tests/codegen/slice-position-bounds-check.rs b/tests/codegen/slice-position-bounds-check.rs
index b494f42b296..57904e5e499 100644
--- a/tests/codegen/slice-position-bounds-check.rs
+++ b/tests/codegen/slice-position-bounds-check.rs
@@ -1,4 +1,3 @@
-// no-system-llvm
 // compile-flags: -O -C panic=abort
 #![crate_type = "lib"]
 
diff --git a/tests/codegen/vec-iter-collect-len.rs b/tests/codegen/vec-iter-collect-len.rs
index 73348ddd063..3a0d6c30919 100644
--- a/tests/codegen/vec-iter-collect-len.rs
+++ b/tests/codegen/vec-iter-collect-len.rs
@@ -1,5 +1,4 @@
 // ignore-debug: the debug assertions get in the way
-// no-system-llvm
 // compile-flags: -O
 #![crate_type="lib"]
 
diff --git a/tests/codegen/vec-optimizes-away.rs b/tests/codegen/vec-optimizes-away.rs
index 6f477a796b6..3be342dabeb 100644
--- a/tests/codegen/vec-optimizes-away.rs
+++ b/tests/codegen/vec-optimizes-away.rs
@@ -1,5 +1,4 @@
 // ignore-debug: the debug assertions get in the way
-// no-system-llvm
 // compile-flags: -O
 #![crate_type = "lib"]
 
diff --git a/tests/coverage-run-rustdoc/doctest.coverage b/tests/coverage-run-rustdoc/doctest.coverage
index 5797784f411..5125dc075ee 100644
--- a/tests/coverage-run-rustdoc/doctest.coverage
+++ b/tests/coverage-run-rustdoc/doctest.coverage
@@ -34,8 +34,7 @@ $DIR/doctest.rs:
    LL|       |//!
    LL|       |//! doctest returning a result:
    LL|      1|//! ```
-   LL|      2|//! #[derive(Debug, PartialEq)]
-                       ^1
+   LL|      1|//! #[derive(Debug, PartialEq)]
    LL|      1|//! struct SomeError {
    LL|      1|//!     msg: String,
    LL|      1|//! }
@@ -63,7 +62,7 @@ $DIR/doctest.rs:
    LL|      1|//!     println!("called some_func()");
    LL|      1|//! }
    LL|       |//!
-   LL|      0|//! #[derive(Debug)]
+   LL|       |//! #[derive(Debug)]
    LL|       |//! struct SomeError;
    LL|       |//!
    LL|       |//! extern crate doctest_crate;
diff --git a/tests/coverage/bad_counter_ids.cov-map b/tests/coverage/bad_counter_ids.cov-map
index 0b8081acfa6..3b51e3ef9de 100644
--- a/tests/coverage/bad_counter_ids.cov-map
+++ b/tests/coverage/bad_counter_ids.cov-map
@@ -1,19 +1,3 @@
-Function name: <bad_counter_ids::Foo as core::cmp::PartialEq>::eq
-Raw bytes (9): 0x[01, 01, 00, 01, 01, 0c, 11, 00, 1a]
-Number of files: 1
-- file 0 => global file 1
-Number of expressions: 0
-Number of file 0 mappings: 1
-- Code(Counter(0)) at (prev + 12, 17) to (start + 0, 26)
-
-Function name: <bad_counter_ids::Foo as core::fmt::Debug>::fmt
-Raw bytes (9): 0x[01, 01, 00, 01, 01, 0c, 0a, 00, 0f]
-Number of files: 1
-- file 0 => global file 1
-Number of expressions: 0
-Number of file 0 mappings: 1
-- Code(Counter(0)) at (prev + 12, 10) to (start + 0, 15)
-
 Function name: bad_counter_ids::eq_bad
 Raw bytes (14): 0x[01, 01, 00, 02, 01, 23, 01, 02, 1f, 00, 03, 01, 00, 02]
 Number of files: 1
diff --git a/tests/coverage/bad_counter_ids.coverage b/tests/coverage/bad_counter_ids.coverage
index d69ebf160ea..5474ec2f785 100644
--- a/tests/coverage/bad_counter_ids.coverage
+++ b/tests/coverage/bad_counter_ids.coverage
@@ -9,7 +9,7 @@
    LL|       |// a too-large counter ID and silently discard the entire function from its
    LL|       |// coverage reports.
    LL|       |
-   LL|      8|#[derive(Debug, PartialEq, Eq)]
+   LL|       |#[derive(Debug, PartialEq, Eq)]
    LL|       |struct Foo(u32);
    LL|       |
    LL|      1|fn eq_good() {
diff --git a/tests/coverage/issue-83601.cov-map b/tests/coverage/issue-83601.cov-map
index f5db3a89750..f2447e3c92c 100644
--- a/tests/coverage/issue-83601.cov-map
+++ b/tests/coverage/issue-83601.cov-map
@@ -1,19 +1,3 @@
-Function name: <issue_83601::Foo as core::cmp::PartialEq>::eq
-Raw bytes (9): 0x[01, 01, 00, 01, 01, 03, 11, 00, 1a]
-Number of files: 1
-- file 0 => global file 1
-Number of expressions: 0
-Number of file 0 mappings: 1
-- Code(Counter(0)) at (prev + 3, 17) to (start + 0, 26)
-
-Function name: <issue_83601::Foo as core::fmt::Debug>::fmt
-Raw bytes (9): 0x[01, 01, 00, 01, 01, 03, 0a, 00, 0f]
-Number of files: 1
-- file 0 => global file 1
-Number of expressions: 0
-Number of file 0 mappings: 1
-- Code(Counter(0)) at (prev + 3, 10) to (start + 0, 15)
-
 Function name: issue_83601::main
 Raw bytes (21): 0x[01, 01, 01, 05, 09, 03, 01, 06, 01, 02, 1c, 05, 03, 09, 01, 1c, 02, 02, 05, 03, 02]
 Number of files: 1
diff --git a/tests/coverage/issue-83601.coverage b/tests/coverage/issue-83601.coverage
index 7995332cad3..e050106e6f0 100644
--- a/tests/coverage/issue-83601.coverage
+++ b/tests/coverage/issue-83601.coverage
@@ -1,7 +1,6 @@
    LL|       |// Shows that rust-lang/rust/83601 is resolved
    LL|       |
-   LL|      3|#[derive(Debug, PartialEq, Eq)]
-                              ^2
+   LL|       |#[derive(Debug, PartialEq, Eq)]
    LL|       |struct Foo(u32);
    LL|       |
    LL|      1|fn main() {
diff --git a/tests/coverage/issue-84561.cov-map b/tests/coverage/issue-84561.cov-map
index 6d577b3d485..88436964af0 100644
--- a/tests/coverage/issue-84561.cov-map
+++ b/tests/coverage/issue-84561.cov-map
@@ -1,11 +1,3 @@
-Function name: <issue_84561::Foo as core::cmp::PartialEq>::eq
-Raw bytes (9): 0x[01, 01, 00, 01, 01, 04, 0a, 00, 13]
-Number of files: 1
-- file 0 => global file 1
-Number of expressions: 0
-Number of file 0 mappings: 1
-- Code(Counter(0)) at (prev + 4, 10) to (start + 0, 19)
-
 Function name: <issue_84561::Foo as core::fmt::Debug>::fmt
 Raw bytes (29): 0x[01, 01, 02, 01, 05, 05, 02, 04, 01, 8a, 01, 05, 01, 25, 05, 01, 25, 00, 26, 02, 01, 09, 00, 0f, 07, 01, 05, 00, 06]
 Number of files: 1
diff --git a/tests/coverage/issue-84561.coverage b/tests/coverage/issue-84561.coverage
index 9080d95eff5..90a2d069d39 100644
--- a/tests/coverage/issue-84561.coverage
+++ b/tests/coverage/issue-84561.coverage
@@ -1,7 +1,7 @@
    LL|       |// This demonstrated Issue #84561: function-like macros produce unintuitive coverage results.
    LL|       |
    LL|       |// failure-status: 101
-   LL|     21|#[derive(PartialEq, Eq)]
+   LL|       |#[derive(PartialEq, Eq)]
    LL|       |struct Foo(u32);
    LL|       |
    LL|       |#[rustfmt::skip]
diff --git a/tests/coverage/partial_eq.cov-map b/tests/coverage/partial_eq.cov-map
index 5e4aae0260b..80670fbfa5a 100644
--- a/tests/coverage/partial_eq.cov-map
+++ b/tests/coverage/partial_eq.cov-map
@@ -1,51 +1,3 @@
-Function name: <partial_eq::Version as core::clone::Clone>::clone (unused)
-Raw bytes (9): 0x[01, 01, 00, 01, 00, 04, 0a, 00, 0f]
-Number of files: 1
-- file 0 => global file 1
-Number of expressions: 0
-Number of file 0 mappings: 1
-- Code(Zero) at (prev + 4, 10) to (start + 0, 15)
-
-Function name: <partial_eq::Version as core::cmp::Ord>::cmp (unused)
-Raw bytes (14): 0x[01, 01, 00, 02, 00, 04, 33, 00, 34, 00, 00, 35, 00, 36]
-Number of files: 1
-- file 0 => global file 1
-Number of expressions: 0
-Number of file 0 mappings: 2
-- Code(Zero) at (prev + 4, 51) to (start + 0, 52)
-- Code(Zero) at (prev + 0, 53) to (start + 0, 54)
-
-Function name: <partial_eq::Version as core::cmp::PartialEq>::eq (unused)
-Raw bytes (14): 0x[01, 01, 00, 02, 00, 04, 18, 00, 19, 00, 00, 20, 00, 21]
-Number of files: 1
-- file 0 => global file 1
-Number of expressions: 0
-Number of file 0 mappings: 2
-- Code(Zero) at (prev + 4, 24) to (start + 0, 25)
-- Code(Zero) at (prev + 0, 32) to (start + 0, 33)
-
-Function name: <partial_eq::Version as core::cmp::PartialOrd>::partial_cmp
-Raw bytes (22): 0x[01, 01, 04, 07, 0b, 00, 09, 0f, 15, 00, 11, 02, 01, 04, 27, 00, 28, 03, 00, 30, 00, 31]
-Number of files: 1
-- file 0 => global file 1
-Number of expressions: 4
-- expression 0 operands: lhs = Expression(1, Add), rhs = Expression(2, Add)
-- expression 1 operands: lhs = Zero, rhs = Counter(2)
-- expression 2 operands: lhs = Expression(3, Add), rhs = Counter(5)
-- expression 3 operands: lhs = Zero, rhs = Counter(4)
-Number of file 0 mappings: 2
-- Code(Counter(0)) at (prev + 4, 39) to (start + 0, 40)
-- Code(Expression(0, Add)) at (prev + 0, 48) to (start + 0, 49)
-    = ((Zero + c2) + ((Zero + c4) + c5))
-
-Function name: <partial_eq::Version as core::fmt::Debug>::fmt
-Raw bytes (9): 0x[01, 01, 00, 01, 01, 04, 11, 00, 16]
-Number of files: 1
-- file 0 => global file 1
-Number of expressions: 0
-Number of file 0 mappings: 1
-- Code(Counter(0)) at (prev + 4, 17) to (start + 0, 22)
-
 Function name: <partial_eq::Version>::new
 Raw bytes (9): 0x[01, 01, 00, 01, 01, 0c, 05, 06, 06]
 Number of files: 1
diff --git a/tests/coverage/partial_eq.coverage b/tests/coverage/partial_eq.coverage
index 6e3696386a7..9de1c933570 100644
--- a/tests/coverage/partial_eq.coverage
+++ b/tests/coverage/partial_eq.coverage
@@ -1,8 +1,7 @@
    LL|       |// This test confirms an earlier problem was resolved, supporting the MIR graph generated by the
    LL|       |// structure of this test.
    LL|       |
-   LL|      2|#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
-                       ^0            ^0      ^0     ^1       ^1 ^0^0
+   LL|       |#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
    LL|       |pub struct Version {
    LL|       |    major: usize,
    LL|       |    minor: usize,
diff --git a/tests/rustdoc/doc-cfg-target-feature.rs b/tests/rustdoc/doc-cfg-target-feature.rs
index f1b000dc823..98d230c978b 100644
--- a/tests/rustdoc/doc-cfg-target-feature.rs
+++ b/tests/rustdoc/doc-cfg-target-feature.rs
@@ -1,7 +1,6 @@
 // only-x86_64
 // compile-flags:--test
 // should-fail
-// no-system-llvm
 
 // #49723: rustdoc didn't add target features when extracting or running doctests
 
diff --git a/tests/ui/array-slice-vec/repeat_empty_ok.stderr b/tests/ui/array-slice-vec/repeat_empty_ok.stderr
index bc3a68c905d..c272d47d961 100644
--- a/tests/ui/array-slice-vec/repeat_empty_ok.stderr
+++ b/tests/ui/array-slice-vec/repeat_empty_ok.stderr
@@ -6,7 +6,7 @@ LL |     let headers = [Header{value: &[]}; 128];
    |
    = note: the `Copy` trait is required because this value will be copied for each element of the array
    = help: consider using `core::array::from_fn` to initialize the array
-   = help: see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html# for more information
+   = help: see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html for more information
 help: consider annotating `Header<'_>` with `#[derive(Copy)]`
    |
 LL + #[derive(Copy)]
@@ -21,7 +21,7 @@ LL |     let headers = [Header{value: &[0]}; 128];
    |
    = note: the `Copy` trait is required because this value will be copied for each element of the array
    = help: consider using `core::array::from_fn` to initialize the array
-   = help: see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html# for more information
+   = help: see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html for more information
 help: consider annotating `Header<'_>` with `#[derive(Copy)]`
    |
 LL + #[derive(Copy)]
diff --git a/tests/ui/associated-consts/issue-105330.rs b/tests/ui/associated-consts/issue-105330.rs
index 6c6dae864f3..285e89cce49 100644
--- a/tests/ui/associated-consts/issue-105330.rs
+++ b/tests/ui/associated-consts/issue-105330.rs
@@ -14,6 +14,5 @@ fn foo<A: TraitWAssocConst<A=32>>() { //~ ERROR E0658
 
 fn main<A: TraitWAssocConst<A=32>>() {
     //~^ ERROR E0658
-    //~| ERROR E0131
     foo::<Demo>();
 }
diff --git a/tests/ui/associated-consts/issue-105330.stderr b/tests/ui/associated-consts/issue-105330.stderr
index b4c021d0f4f..452367bed12 100644
--- a/tests/ui/associated-consts/issue-105330.stderr
+++ b/tests/ui/associated-consts/issue-105330.stderr
@@ -43,13 +43,7 @@ LL | impl TraitWAssocConst for impl Demo {
    |
    = note: `impl Trait` is only allowed in arguments and return types of functions and methods
 
-error[E0131]: `main` function is not allowed to have generic parameters
-  --> $DIR/issue-105330.rs:15:8
-   |
-LL | fn main<A: TraitWAssocConst<A=32>>() {
-   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^ `main` cannot have generic parameters
-
-error: aborting due to 6 previous errors
+error: aborting due to 5 previous errors
 
-Some errors have detailed explanations: E0131, E0404, E0562, E0658.
-For more information about an error, try `rustc --explain E0131`.
+Some errors have detailed explanations: E0404, E0562, E0658.
+For more information about an error, try `rustc --explain E0404`.
diff --git a/tests/ui/associated-types/impl-wf-cycle-1.stderr b/tests/ui/associated-types/impl-wf-cycle-1.stderr
index 5fa36733f66..d642f9f0e36 100644
--- a/tests/ui/associated-types/impl-wf-cycle-1.stderr
+++ b/tests/ui/associated-types/impl-wf-cycle-1.stderr
@@ -7,6 +7,9 @@ LL | | where
 LL | |     Self::A: Baz,
 LL | |     Self::B: Fiz,
    | |_________________^
+LL |   {
+LL |       type A = ();
+   |       ------ associated type `<(T,) as Grault>::A` is specified here
    |
 note: required for `(T,)` to implement `Grault`
   --> $DIR/impl-wf-cycle-1.rs:15:17
@@ -18,6 +21,10 @@ LL |     Self::A: Baz,
    |              --- unsatisfied trait bound introduced here
    = note: 1 redundant requirement hidden
    = note: required for `(T,)` to implement `Grault`
+help: associated type for the current `impl` cannot be restricted in `where` clauses, remove this bound
+   |
+LL -     Self::A: Baz,
+   |
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/associated-types/impl-wf-cycle-2.stderr b/tests/ui/associated-types/impl-wf-cycle-2.stderr
index 17a96bbd934..9454d1d6697 100644
--- a/tests/ui/associated-types/impl-wf-cycle-2.stderr
+++ b/tests/ui/associated-types/impl-wf-cycle-2.stderr
@@ -6,6 +6,9 @@ LL | |
 LL | | where
 LL | |     Self::A: Copy,
    | |__________________^
+LL |   {
+LL |       type A = ();
+   |       ------ associated type `<(T,) as Grault>::A` is specified here
    |
 note: required for `(T,)` to implement `Grault`
   --> $DIR/impl-wf-cycle-2.rs:7:17
@@ -15,6 +18,11 @@ LL | impl<T: Grault> Grault for (T,)
 ...
 LL |     Self::A: Copy,
    |              ---- unsatisfied trait bound introduced here
+help: associated type for the current `impl` cannot be restricted in `where` clauses, remove this bound
+   |
+LL - where
+LL -     Self::A: Copy,
+   |
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/associated-types/impl-wf-cycle-3.rs b/tests/ui/associated-types/impl-wf-cycle-3.rs
new file mode 100644
index 00000000000..044033c5e8a
--- /dev/null
+++ b/tests/ui/associated-types/impl-wf-cycle-3.rs
@@ -0,0 +1,13 @@
+trait A<T> {}
+
+trait B {
+    type Type;
+}
+
+impl<T> B for T //~ ERROR overflow evaluating the requirement
+where
+    T: A<Self::Type>,
+{
+    type Type = bool;
+}
+fn main() {}
diff --git a/tests/ui/associated-types/impl-wf-cycle-3.stderr b/tests/ui/associated-types/impl-wf-cycle-3.stderr
new file mode 100644
index 00000000000..d3ca06f890b
--- /dev/null
+++ b/tests/ui/associated-types/impl-wf-cycle-3.stderr
@@ -0,0 +1,27 @@
+error[E0275]: overflow evaluating the requirement `<T as B>::Type == <T as B>::Type`
+  --> $DIR/impl-wf-cycle-3.rs:7:1
+   |
+LL | / impl<T> B for T
+LL | | where
+LL | |     T: A<Self::Type>,
+   | |_____________________^
+LL |   {
+LL |       type Type = bool;
+   |       --------- associated type `<T as B>::Type` is specified here
+   |
+note: required for `T` to implement `B`
+  --> $DIR/impl-wf-cycle-3.rs:7:9
+   |
+LL | impl<T> B for T
+   |         ^     ^
+LL | where
+LL |     T: A<Self::Type>,
+   |        ------------- unsatisfied trait bound introduced here
+help: replace the associated type with the type specified in this `impl`
+   |
+LL |     T: A<bool>,
+   |          ~~~~
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0275`.
diff --git a/tests/ui/associated-types/impl-wf-cycle-4.rs b/tests/ui/associated-types/impl-wf-cycle-4.rs
new file mode 100644
index 00000000000..bfa8adc71a1
--- /dev/null
+++ b/tests/ui/associated-types/impl-wf-cycle-4.rs
@@ -0,0 +1,15 @@
+trait Filter {
+    type ToMatch;
+}
+
+impl<T> Filter for T //~ ERROR overflow evaluating the requirement
+where
+    T: Fn(Self::ToMatch),
+{
+}
+
+struct JustFilter<F: Filter> {
+    filter: F,
+}
+
+fn main() {}
diff --git a/tests/ui/associated-types/impl-wf-cycle-4.stderr b/tests/ui/associated-types/impl-wf-cycle-4.stderr
new file mode 100644
index 00000000000..cdbac267d34
--- /dev/null
+++ b/tests/ui/associated-types/impl-wf-cycle-4.stderr
@@ -0,0 +1,25 @@
+error[E0275]: overflow evaluating the requirement `<T as Filter>::ToMatch == <T as Filter>::ToMatch`
+  --> $DIR/impl-wf-cycle-4.rs:5:1
+   |
+LL | / impl<T> Filter for T
+LL | | where
+LL | |     T: Fn(Self::ToMatch),
+   | |_________________________^
+   |
+note: required for `T` to implement `Filter`
+  --> $DIR/impl-wf-cycle-4.rs:5:9
+   |
+LL | impl<T> Filter for T
+   |         ^^^^^^     ^
+LL | where
+LL |     T: Fn(Self::ToMatch),
+   |        ----------------- unsatisfied trait bound introduced here
+note: associated types for the current `impl` cannot be restricted in `where` clauses
+  --> $DIR/impl-wf-cycle-4.rs:7:11
+   |
+LL |     T: Fn(Self::ToMatch),
+   |           ^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0275`.
diff --git a/tests/ui/associated-types/impl-wf-cycle-5.fixed b/tests/ui/associated-types/impl-wf-cycle-5.fixed
new file mode 100644
index 00000000000..bff6ca90975
--- /dev/null
+++ b/tests/ui/associated-types/impl-wf-cycle-5.fixed
@@ -0,0 +1,31 @@
+// run-rustfix
+
+trait Baz {}
+impl Baz for () {}
+impl<T> Baz for (T,) {}
+
+trait Fiz {}
+impl Fiz for bool {}
+
+trait Grault {
+    type A;
+    type B;
+}
+
+impl Grault for () {
+    type A = ();
+    type B = bool;
+}
+
+impl<T> Grault for (T,)
+//~^ ERROR overflow evaluating the requirement `<(T,) as Grault>::A == _`
+where
+    T: Grault,
+{
+    type A = ();
+    type B = bool;
+}
+
+fn main() {
+    let _: <((),) as Grault>::A = ();
+}
diff --git a/tests/ui/associated-types/impl-wf-cycle-5.rs b/tests/ui/associated-types/impl-wf-cycle-5.rs
new file mode 100644
index 00000000000..a822e1fb008
--- /dev/null
+++ b/tests/ui/associated-types/impl-wf-cycle-5.rs
@@ -0,0 +1,32 @@
+// run-rustfix
+
+trait Baz {}
+impl Baz for () {}
+impl<T> Baz for (T,) {}
+
+trait Fiz {}
+impl Fiz for bool {}
+
+trait Grault {
+    type A;
+    type B;
+}
+
+impl Grault for () {
+    type A = ();
+    type B = bool;
+}
+
+impl<T> Grault for (T,)
+//~^ ERROR overflow evaluating the requirement `<(T,) as Grault>::A == _`
+where
+    T: Grault,
+    Self::A: Baz,
+{
+    type A = ();
+    type B = bool;
+}
+
+fn main() {
+    let _: <((),) as Grault>::A = ();
+}
diff --git a/tests/ui/associated-types/impl-wf-cycle-5.stderr b/tests/ui/associated-types/impl-wf-cycle-5.stderr
new file mode 100644
index 00000000000..284a50bb9a3
--- /dev/null
+++ b/tests/ui/associated-types/impl-wf-cycle-5.stderr
@@ -0,0 +1,31 @@
+error[E0275]: overflow evaluating the requirement `<(T,) as Grault>::A == _`
+  --> $DIR/impl-wf-cycle-5.rs:20:1
+   |
+LL | / impl<T> Grault for (T,)
+LL | |
+LL | | where
+LL | |     T: Grault,
+LL | |     Self::A: Baz,
+   | |_________________^
+LL |   {
+LL |       type A = ();
+   |       ------ associated type `<(T,) as Grault>::A` is specified here
+   |
+note: required for `(T,)` to implement `Grault`
+  --> $DIR/impl-wf-cycle-5.rs:20:9
+   |
+LL | impl<T> Grault for (T,)
+   |         ^^^^^^     ^^^^
+...
+LL |     Self::A: Baz,
+   |              --- unsatisfied trait bound introduced here
+help: associated type for the current `impl` cannot be restricted in `where` clauses, remove this bound
+   |
+LL -     T: Grault,
+LL -     Self::A: Baz,
+LL +     T: Grault,
+   |
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0275`.
diff --git a/tests/ui/associated-types/impl-wf-cycle-6.fixed b/tests/ui/associated-types/impl-wf-cycle-6.fixed
new file mode 100644
index 00000000000..73ed64f7ce3
--- /dev/null
+++ b/tests/ui/associated-types/impl-wf-cycle-6.fixed
@@ -0,0 +1,30 @@
+// run-rustfix
+
+trait Baz {}
+impl Baz for () {}
+impl<T> Baz for (T,) {}
+
+trait Fiz {}
+impl Fiz for bool {}
+
+trait Grault {
+    type A;
+    type B;
+}
+
+impl Grault for () {
+    type A = ();
+    type B = bool;
+}
+
+impl<T: Grault> Grault for (T,)
+//~^ ERROR overflow evaluating the requirement `<(T,) as Grault>::A == _`
+
+{
+    type A = ();
+    type B = bool;
+}
+
+fn main() {
+    let _: <((),) as Grault>::A = ();
+}
diff --git a/tests/ui/associated-types/impl-wf-cycle-6.rs b/tests/ui/associated-types/impl-wf-cycle-6.rs
new file mode 100644
index 00000000000..20d635cac5d
--- /dev/null
+++ b/tests/ui/associated-types/impl-wf-cycle-6.rs
@@ -0,0 +1,31 @@
+// run-rustfix
+
+trait Baz {}
+impl Baz for () {}
+impl<T> Baz for (T,) {}
+
+trait Fiz {}
+impl Fiz for bool {}
+
+trait Grault {
+    type A;
+    type B;
+}
+
+impl Grault for () {
+    type A = ();
+    type B = bool;
+}
+
+impl<T: Grault> Grault for (T,)
+//~^ ERROR overflow evaluating the requirement `<(T,) as Grault>::A == _`
+where
+    Self::A: Baz,
+{
+    type A = ();
+    type B = bool;
+}
+
+fn main() {
+    let _: <((),) as Grault>::A = ();
+}
diff --git a/tests/ui/associated-types/impl-wf-cycle-6.stderr b/tests/ui/associated-types/impl-wf-cycle-6.stderr
new file mode 100644
index 00000000000..c9b5d8060be
--- /dev/null
+++ b/tests/ui/associated-types/impl-wf-cycle-6.stderr
@@ -0,0 +1,29 @@
+error[E0275]: overflow evaluating the requirement `<(T,) as Grault>::A == _`
+  --> $DIR/impl-wf-cycle-6.rs:20:1
+   |
+LL | / impl<T: Grault> Grault for (T,)
+LL | |
+LL | | where
+LL | |     Self::A: Baz,
+   | |_________________^
+LL |   {
+LL |       type A = ();
+   |       ------ associated type `<(T,) as Grault>::A` is specified here
+   |
+note: required for `(T,)` to implement `Grault`
+  --> $DIR/impl-wf-cycle-6.rs:20:17
+   |
+LL | impl<T: Grault> Grault for (T,)
+   |                 ^^^^^^     ^^^^
+...
+LL |     Self::A: Baz,
+   |              --- unsatisfied trait bound introduced here
+help: associated type for the current `impl` cannot be restricted in `where` clauses, remove this bound
+   |
+LL - where
+LL -     Self::A: Baz,
+   |
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0275`.
diff --git a/tests/ui/associated-types/issue-38821.rs b/tests/ui/associated-types/issue-38821.rs
index 6753860e9ff..34c35d7acf1 100644
--- a/tests/ui/associated-types/issue-38821.rs
+++ b/tests/ui/associated-types/issue-38821.rs
@@ -22,7 +22,22 @@ pub trait Column: Expression {}
 
 #[derive(Debug, Copy, Clone)]
 //~^ ERROR the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+//~| ERROR the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+//~| ERROR the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+//~| ERROR the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+//~| ERROR the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+//~| ERROR the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+//~| ERROR the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+//~| ERROR the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+//~| ERROR the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+//~| ERROR the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+//~| ERROR the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+//~| ERROR the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+//~| ERROR the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+//~| ERROR the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
 pub enum ColumnInsertValue<Col, Expr> where
+//~^ ERROR the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+//~| ERROR the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
     Col: Column,
     Expr: Expression<SqlType=<Col::SqlType as IntoNullable>::Nullable>,
 {
diff --git a/tests/ui/associated-types/issue-38821.stderr b/tests/ui/associated-types/issue-38821.stderr
index 8b628f5ae6d..0e34f541ea3 100644
--- a/tests/ui/associated-types/issue-38821.stderr
+++ b/tests/ui/associated-types/issue-38821.stderr
@@ -17,6 +17,272 @@ help: consider further restricting the associated type
 LL |     Expr: Expression<SqlType=<Col::SqlType as IntoNullable>::Nullable>, <Col as Expression>::SqlType: NotNull,
    |                                                                       +++++++++++++++++++++++++++++++++++++++
 
-error: aborting due to 1 previous error
+error[E0277]: the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+  --> $DIR/issue-38821.rs:38:1
+   |
+LL | pub enum ColumnInsertValue<Col, Expr> where
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `NotNull` is not implemented for `<Col as Expression>::SqlType`
+   |
+note: required for `<Col as Expression>::SqlType` to implement `IntoNullable`
+  --> $DIR/issue-38821.rs:9:18
+   |
+LL | impl<T: NotNull> IntoNullable for T {
+   |         -------  ^^^^^^^^^^^^     ^
+   |         |
+   |         unsatisfied trait bound introduced here
+help: consider extending the `where` clause, but there might be an alternative better way to express this requirement
+   |
+LL |     Expr: Expression<SqlType=<Col::SqlType as IntoNullable>::Nullable>, <Col as Expression>::SqlType: NotNull
+   |                                                                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+error[E0277]: the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+  --> $DIR/issue-38821.rs:38:1
+   |
+LL | / pub enum ColumnInsertValue<Col, Expr> where
+LL | |
+LL | |
+LL | |     Col: Column,
+...  |
+LL | |     Default(Col),
+LL | | }
+   | |_^ the trait `NotNull` is not implemented for `<Col as Expression>::SqlType`
+   |
+note: required for `<Col as Expression>::SqlType` to implement `IntoNullable`
+  --> $DIR/issue-38821.rs:9:18
+   |
+LL | impl<T: NotNull> IntoNullable for T {
+   |         -------  ^^^^^^^^^^^^     ^
+   |         |
+   |         unsatisfied trait bound introduced here
+help: consider extending the `where` clause, but there might be an alternative better way to express this requirement
+   |
+LL |     Expr: Expression<SqlType=<Col::SqlType as IntoNullable>::Nullable>, <Col as Expression>::SqlType: NotNull
+   |                                                                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+error[E0277]: the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+  --> $DIR/issue-38821.rs:23:10
+   |
+LL | #[derive(Debug, Copy, Clone)]
+   |          ^^^^^ the trait `NotNull` is not implemented for `<Col as Expression>::SqlType`
+   |
+note: required for `<Col as Expression>::SqlType` to implement `IntoNullable`
+  --> $DIR/issue-38821.rs:9:18
+   |
+LL | impl<T: NotNull> IntoNullable for T {
+   |         -------  ^^^^^^^^^^^^     ^
+   |         |
+   |         unsatisfied trait bound introduced here
+   = note: this error originates in the derive macro `Debug` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider further restricting the associated type
+   |
+LL |     Expr: Expression<SqlType=<Col::SqlType as IntoNullable>::Nullable>, <Col as Expression>::SqlType: NotNull,
+   |                                                                       +++++++++++++++++++++++++++++++++++++++
+
+error[E0277]: the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+  --> $DIR/issue-38821.rs:23:10
+   |
+LL | #[derive(Debug, Copy, Clone)]
+   |          ^^^^^ the trait `NotNull` is not implemented for `<Col as Expression>::SqlType`
+   |
+note: required for `<Col as Expression>::SqlType` to implement `IntoNullable`
+  --> $DIR/issue-38821.rs:9:18
+   |
+LL | impl<T: NotNull> IntoNullable for T {
+   |         -------  ^^^^^^^^^^^^     ^
+   |         |
+   |         unsatisfied trait bound introduced here
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+   = note: this error originates in the derive macro `Debug` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider further restricting the associated type
+   |
+LL |     Expr: Expression<SqlType=<Col::SqlType as IntoNullable>::Nullable>, <Col as Expression>::SqlType: NotNull,
+   |                                                                       +++++++++++++++++++++++++++++++++++++++
+
+error[E0277]: the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+  --> $DIR/issue-38821.rs:23:10
+   |
+LL | #[derive(Debug, Copy, Clone)]
+   |          ^^^^^ the trait `NotNull` is not implemented for `<Col as Expression>::SqlType`
+   |
+note: required for `<Col as Expression>::SqlType` to implement `IntoNullable`
+  --> $DIR/issue-38821.rs:9:18
+   |
+LL | impl<T: NotNull> IntoNullable for T {
+   |         -------  ^^^^^^^^^^^^     ^
+   |         |
+   |         unsatisfied trait bound introduced here
+   = note: this error originates in the derive macro `Debug` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0277]: the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+  --> $DIR/issue-38821.rs:23:10
+   |
+LL | #[derive(Debug, Copy, Clone)]
+   |          ^^^^^ the trait `NotNull` is not implemented for `<Col as Expression>::SqlType`
+   |
+note: required for `<Col as Expression>::SqlType` to implement `IntoNullable`
+  --> $DIR/issue-38821.rs:9:18
+   |
+LL | impl<T: NotNull> IntoNullable for T {
+   |         -------  ^^^^^^^^^^^^     ^
+   |         |
+   |         unsatisfied trait bound introduced here
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+   = note: this error originates in the derive macro `Debug` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0277]: the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+  --> $DIR/issue-38821.rs:23:17
+   |
+LL | #[derive(Debug, Copy, Clone)]
+   |                 ^^^^ the trait `NotNull` is not implemented for `<Col as Expression>::SqlType`
+   |
+note: required for `<Col as Expression>::SqlType` to implement `IntoNullable`
+  --> $DIR/issue-38821.rs:9:18
+   |
+LL | impl<T: NotNull> IntoNullable for T {
+   |         -------  ^^^^^^^^^^^^     ^
+   |         |
+   |         unsatisfied trait bound introduced here
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+   = note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider further restricting the associated type
+   |
+LL |     Expr: Expression<SqlType=<Col::SqlType as IntoNullable>::Nullable>, <Col as Expression>::SqlType: NotNull,
+   |                                                                       +++++++++++++++++++++++++++++++++++++++
+
+error[E0277]: the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+  --> $DIR/issue-38821.rs:23:23
+   |
+LL | #[derive(Debug, Copy, Clone)]
+   |                       ^^^^^ the trait `NotNull` is not implemented for `<Col as Expression>::SqlType`
+   |
+note: required for `<Col as Expression>::SqlType` to implement `IntoNullable`
+  --> $DIR/issue-38821.rs:9:18
+   |
+LL | impl<T: NotNull> IntoNullable for T {
+   |         -------  ^^^^^^^^^^^^     ^
+   |         |
+   |         unsatisfied trait bound introduced here
+   = note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider further restricting the associated type
+   |
+LL |     Expr: Expression<SqlType=<Col::SqlType as IntoNullable>::Nullable>, <Col as Expression>::SqlType: NotNull,
+   |                                                                       +++++++++++++++++++++++++++++++++++++++
+
+error[E0277]: the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+  --> $DIR/issue-38821.rs:23:23
+   |
+LL | #[derive(Debug, Copy, Clone)]
+   |                       ^^^^^ the trait `NotNull` is not implemented for `<Col as Expression>::SqlType`
+   |
+note: required for `<Col as Expression>::SqlType` to implement `IntoNullable`
+  --> $DIR/issue-38821.rs:9:18
+   |
+LL | impl<T: NotNull> IntoNullable for T {
+   |         -------  ^^^^^^^^^^^^     ^
+   |         |
+   |         unsatisfied trait bound introduced here
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+   = note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider further restricting the associated type
+   |
+LL |     Expr: Expression<SqlType=<Col::SqlType as IntoNullable>::Nullable>, <Col as Expression>::SqlType: NotNull,
+   |                                                                       +++++++++++++++++++++++++++++++++++++++
+
+error[E0277]: the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+  --> $DIR/issue-38821.rs:23:23
+   |
+LL | #[derive(Debug, Copy, Clone)]
+   |                       ^^^^^ the trait `NotNull` is not implemented for `<Col as Expression>::SqlType`
+   |
+note: required for `<Col as Expression>::SqlType` to implement `IntoNullable`
+  --> $DIR/issue-38821.rs:9:18
+   |
+LL | impl<T: NotNull> IntoNullable for T {
+   |         -------  ^^^^^^^^^^^^     ^
+   |         |
+   |         unsatisfied trait bound introduced here
+   = note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0277]: the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+  --> $DIR/issue-38821.rs:23:23
+   |
+LL | #[derive(Debug, Copy, Clone)]
+   |                       ^^^^^ the trait `NotNull` is not implemented for `<Col as Expression>::SqlType`
+   |
+note: required for `<Col as Expression>::SqlType` to implement `IntoNullable`
+  --> $DIR/issue-38821.rs:9:18
+   |
+LL | impl<T: NotNull> IntoNullable for T {
+   |         -------  ^^^^^^^^^^^^     ^
+   |         |
+   |         unsatisfied trait bound introduced here
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+   = note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0277]: the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+  --> $DIR/issue-38821.rs:23:10
+   |
+LL | #[derive(Debug, Copy, Clone)]
+   |          ^^^^^ the trait `NotNull` is not implemented for `<Col as Expression>::SqlType`
+   |
+note: required for `<Col as Expression>::SqlType` to implement `IntoNullable`
+  --> $DIR/issue-38821.rs:9:18
+   |
+LL | impl<T: NotNull> IntoNullable for T {
+   |         -------  ^^^^^^^^^^^^     ^
+   |         |
+   |         unsatisfied trait bound introduced here
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+   = note: this error originates in the derive macro `Debug` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0277]: the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+  --> $DIR/issue-38821.rs:23:10
+   |
+LL | #[derive(Debug, Copy, Clone)]
+   |          ^^^^^ the trait `NotNull` is not implemented for `<Col as Expression>::SqlType`
+   |
+note: required for `<Col as Expression>::SqlType` to implement `IntoNullable`
+  --> $DIR/issue-38821.rs:9:18
+   |
+LL | impl<T: NotNull> IntoNullable for T {
+   |         -------  ^^^^^^^^^^^^     ^
+   |         |
+   |         unsatisfied trait bound introduced here
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+   = note: this error originates in the derive macro `Debug` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0277]: the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+  --> $DIR/issue-38821.rs:23:23
+   |
+LL | #[derive(Debug, Copy, Clone)]
+   |                       ^^^^^ the trait `NotNull` is not implemented for `<Col as Expression>::SqlType`
+   |
+note: required for `<Col as Expression>::SqlType` to implement `IntoNullable`
+  --> $DIR/issue-38821.rs:9:18
+   |
+LL | impl<T: NotNull> IntoNullable for T {
+   |         -------  ^^^^^^^^^^^^     ^
+   |         |
+   |         unsatisfied trait bound introduced here
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+   = note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0277]: the trait bound `<Col as Expression>::SqlType: NotNull` is not satisfied
+  --> $DIR/issue-38821.rs:23:23
+   |
+LL | #[derive(Debug, Copy, Clone)]
+   |                       ^^^^^ the trait `NotNull` is not implemented for `<Col as Expression>::SqlType`
+   |
+note: required for `<Col as Expression>::SqlType` to implement `IntoNullable`
+  --> $DIR/issue-38821.rs:9:18
+   |
+LL | impl<T: NotNull> IntoNullable for T {
+   |         -------  ^^^^^^^^^^^^     ^
+   |         |
+   |         unsatisfied trait bound introduced here
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+   = note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 16 previous errors
 
 For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/async-await/async-fn/simple.rs b/tests/ui/async-await/async-fn/simple.rs
new file mode 100644
index 00000000000..99a5d56a309
--- /dev/null
+++ b/tests/ui/async-await/async-fn/simple.rs
@@ -0,0 +1,16 @@
+// edition: 2021
+// check-pass
+
+#![feature(async_fn_traits)]
+
+use std::ops::AsyncFn;
+
+async fn foo() {}
+
+async fn call_asyncly(f: impl AsyncFn(i32) -> i32) -> i32 {
+    f(1).await
+}
+
+fn main() {
+    let fut = call_asyncly(|x| async move { x + 1 });
+}
diff --git a/tests/ui/check-cfg/well-known-values.stderr b/tests/ui/check-cfg/well-known-values.stderr
index 814d4736197..d7d538c0b9e 100644
--- a/tests/ui/check-cfg/well-known-values.stderr
+++ b/tests/ui/check-cfg/well-known-values.stderr
@@ -125,7 +125,7 @@ warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
 LL |     target_env = "_UNEXPECTED_VALUE",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: expected values for `target_env` are: ``, `eabihf`, `gnu`, `gnueabihf`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `psx`, `relibc`, `sgx`, `uclibc`
+   = note: expected values for `target_env` are: ``, `eabihf`, `gnu`, `gnueabihf`, `msvc`, `musl`, `newlib`, `nto70`, `nto71`, `ohos`, `preview2`, `psx`, `relibc`, `sgx`, `uclibc`
    = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
@@ -134,7 +134,7 @@ warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
 LL |     target_family = "_UNEXPECTED_VALUE",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: expected values for `target_family` are: `unix`, `wasm`, `windows`
+   = note: expected values for `target_family` are: `unix`, `wasi`, `wasm`, `windows`
    = note: see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration
 
 warning: unexpected `cfg` condition value: `_UNEXPECTED_VALUE`
diff --git a/tests/ui/coercion/issue-53475.rs b/tests/ui/coercion/issue-53475.rs
index 3770c024fb9..f389169f954 100644
--- a/tests/ui/coercion/issue-53475.rs
+++ b/tests/ui/coercion/issue-53475.rs
@@ -3,7 +3,7 @@
 use std::any::Any;
 use std::ops::CoerceUnsized;
 
-struct Foo<T> {
+struct Foo<T: ?Sized> {
     data: Box<T>,
 }
 
diff --git a/tests/ui/const-generics/bad-generic-in-copy-impl.rs b/tests/ui/const-generics/bad-generic-in-copy-impl.rs
index b5663464cf4..092a7af236b 100644
--- a/tests/ui/const-generics/bad-generic-in-copy-impl.rs
+++ b/tests/ui/const-generics/bad-generic-in-copy-impl.rs
@@ -2,6 +2,7 @@
 pub struct Foo {
     x: [u8; SIZE],
     //~^ ERROR mismatched types
+    //~| ERROR mismatched types
 }
 
 const SIZE: u32 = 1;
diff --git a/tests/ui/const-generics/bad-generic-in-copy-impl.stderr b/tests/ui/const-generics/bad-generic-in-copy-impl.stderr
index d60d8ec0e90..fbd546d42fb 100644
--- a/tests/ui/const-generics/bad-generic-in-copy-impl.stderr
+++ b/tests/ui/const-generics/bad-generic-in-copy-impl.stderr
@@ -4,6 +4,14 @@ error[E0308]: mismatched types
 LL |     x: [u8; SIZE],
    |             ^^^^ expected `usize`, found `u32`
 
-error: aborting due to 1 previous error
+error[E0308]: mismatched types
+  --> $DIR/bad-generic-in-copy-impl.rs:3:13
+   |
+LL |     x: [u8; SIZE],
+   |             ^^^^ expected `usize`, found `u32`
+   |
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/const-generics/issues/issue-61336-2.stderr b/tests/ui/const-generics/issues/issue-61336-2.stderr
index 9064c2d0b94..b0864689f74 100644
--- a/tests/ui/const-generics/issues/issue-61336-2.stderr
+++ b/tests/ui/const-generics/issues/issue-61336-2.stderr
@@ -6,7 +6,7 @@ LL |     [x; { N }]
    |
    = note: the `Copy` trait is required because this value will be copied for each element of the array
    = help: consider using `core::array::from_fn` to initialize the array
-   = help: see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html# for more information
+   = help: see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html for more information
 help: consider restricting type parameter `T`
    |
 LL | fn g<T: std::marker::Copy, const N: usize>(x: T) -> [T; N] {
diff --git a/tests/ui/const-generics/issues/issue-61336.stderr b/tests/ui/const-generics/issues/issue-61336.stderr
index 9935d6c1689..111afbda343 100644
--- a/tests/ui/const-generics/issues/issue-61336.stderr
+++ b/tests/ui/const-generics/issues/issue-61336.stderr
@@ -6,7 +6,7 @@ LL |     [x; N]
    |
    = note: the `Copy` trait is required because this value will be copied for each element of the array
    = help: consider using `core::array::from_fn` to initialize the array
-   = help: see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html# for more information
+   = help: see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html for more information
 help: consider restricting type parameter `T`
    |
 LL | fn g<T: std::marker::Copy, const N: usize>(x: T) -> [T; N] {
diff --git a/tests/ui/consts/const-blocks/migrate-fail.stderr b/tests/ui/consts/const-blocks/migrate-fail.stderr
index 95fece0ae8a..3c116026e58 100644
--- a/tests/ui/consts/const-blocks/migrate-fail.stderr
+++ b/tests/ui/consts/const-blocks/migrate-fail.stderr
@@ -7,7 +7,7 @@ LL |         let arr: [Option<Bar>; 2] = [x; 2];
    = note: required for `Option<Bar>` to implement `Copy`
    = note: the `Copy` trait is required because this value will be copied for each element of the array
    = help: consider using `core::array::from_fn` to initialize the array
-   = help: see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html# for more information
+   = help: see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html for more information
 help: consider annotating `Bar` with `#[derive(Copy)]`
    |
 LL + #[derive(Copy)]
@@ -23,7 +23,7 @@ LL |         let arr: [Option<Bar>; 2] = [x; 2];
    = note: required for `Option<Bar>` to implement `Copy`
    = note: the `Copy` trait is required because this value will be copied for each element of the array
    = help: consider using `core::array::from_fn` to initialize the array
-   = help: see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html# for more information
+   = help: see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html for more information
 help: consider annotating `Bar` with `#[derive(Copy)]`
    |
 LL + #[derive(Copy)]
diff --git a/tests/ui/consts/const-blocks/nll-fail.stderr b/tests/ui/consts/const-blocks/nll-fail.stderr
index ed1dc78f77d..ff2b62da668 100644
--- a/tests/ui/consts/const-blocks/nll-fail.stderr
+++ b/tests/ui/consts/const-blocks/nll-fail.stderr
@@ -7,7 +7,7 @@ LL |         let arr: [Option<Bar>; 2] = [x; 2];
    = note: required for `Option<Bar>` to implement `Copy`
    = note: the `Copy` trait is required because this value will be copied for each element of the array
    = help: consider using `core::array::from_fn` to initialize the array
-   = help: see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html# for more information
+   = help: see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html for more information
 help: consider annotating `Bar` with `#[derive(Copy)]`
    |
 LL + #[derive(Copy)]
@@ -23,7 +23,7 @@ LL |         let arr: [Option<Bar>; 2] = [x; 2];
    = note: required for `Option<Bar>` to implement `Copy`
    = note: the `Copy` trait is required because this value will be copied for each element of the array
    = help: consider using `core::array::from_fn` to initialize the array
-   = help: see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html# for more information
+   = help: see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html for more information
 help: consider annotating `Bar` with `#[derive(Copy)]`
    |
 LL + #[derive(Copy)]
diff --git a/tests/ui/consts/const-err-late.stderr b/tests/ui/consts/const-err-late.stderr
index 35c3d000117..53badeafa35 100644
--- a/tests/ui/consts/const-err-late.stderr
+++ b/tests/ui/consts/const-err-late.stderr
@@ -30,6 +30,14 @@ LL |     black_box((S::<i32>::FOO, S::<u32>::FOO));
    |
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
+note: erroneous constant encountered
+  --> $DIR/const-err-late.rs:19:31
+   |
+LL |     black_box((S::<i32>::FOO, S::<u32>::FOO));
+   |                               ^^^^^^^^^^^^^
+   |
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
 error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0080`.
diff --git a/tests/ui/consts/is_val_statically_known.rs b/tests/ui/consts/is_val_statically_known.rs
new file mode 100644
index 00000000000..b0565842eb4
--- /dev/null
+++ b/tests/ui/consts/is_val_statically_known.rs
@@ -0,0 +1,15 @@
+// run-pass
+
+#![feature(core_intrinsics)]
+#![feature(is_val_statically_known)]
+
+use std::intrinsics::is_val_statically_known;
+
+const CONST_TEST: bool = unsafe { is_val_statically_known(0) };
+
+fn main() {
+    if CONST_TEST {
+        unreachable!("currently expected to return false during const eval");
+        // but note that this is not a guarantee!
+    }
+}
diff --git a/tests/ui/consts/issue-65348.rs b/tests/ui/consts/issue-65348.rs
index 5eafa831d63..01bf2a3fa42 100644
--- a/tests/ui/consts/issue-65348.rs
+++ b/tests/ui/consts/issue-65348.rs
@@ -8,15 +8,16 @@ impl<T> Generic<T> {
     const ARRAY_FIELD: Generic<(i32, [T; 0])> = Generic((0, []));
 }
 
-pub const fn array<T>() ->  &'static T {
+pub const fn array<T>() -> &'static T {
+    #[allow(unconditional_panic)]
     &Generic::<T>::ARRAY[0]
 }
 
-pub const fn newtype_array<T>() ->  &'static T {
+pub const fn newtype_array<T>() -> &'static T {
     &Generic::<T>::NEWTYPE_ARRAY.0[0]
 }
 
-pub const fn array_field<T>() ->  &'static T {
+pub const fn array_field<T>() -> &'static T {
     &(Generic::<T>::ARRAY_FIELD.0).1[0]
 }
 
diff --git a/tests/ui/did_you_mean/bad-assoc-ty.stderr b/tests/ui/did_you_mean/bad-assoc-ty.stderr
index 3c474d19d1d..eed01267224 100644
--- a/tests/ui/did_you_mean/bad-assoc-ty.stderr
+++ b/tests/ui/did_you_mean/bad-assoc-ty.stderr
@@ -191,7 +191,14 @@ error[E0223]: ambiguous associated type
   --> $DIR/bad-assoc-ty.rs:33:10
    |
 LL | type H = Fn(u8) -> (u8)::Output;
-   |          ^^^^^^^^^^^^^^^^^^^^^^ help: use fully-qualified syntax: `<(dyn Fn(u8) -> u8 + 'static) as IntoFuture>::Output`
+   |          ^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: use fully-qualified syntax
+   |
+LL | type H = <(dyn Fn(u8) -> u8 + 'static) as AsyncFnOnce>::Output;
+   |          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+LL | type H = <(dyn Fn(u8) -> u8 + 'static) as IntoFuture>::Output;
+   |          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 error[E0223]: ambiguous associated type
   --> $DIR/bad-assoc-ty.rs:39:19
diff --git a/tests/ui/dst/dst-bad-assign-3.stderr b/tests/ui/dst/dst-bad-assign-3.stderr
index 6dd3434fd21..007f6b898be 100644
--- a/tests/ui/dst/dst-bad-assign-3.stderr
+++ b/tests/ui/dst/dst-bad-assign-3.stderr
@@ -8,6 +8,7 @@ LL |     f5.2 = Bar1 {f: 36};
    |
    = note: expected trait object `dyn ToBar`
                     found struct `Bar1`
+   = help: `Bar1` implements `ToBar` so you could box the found value and coerce it to the trait object `Box<dyn ToBar>`, you will have to change the expected type as well
 
 error[E0277]: the size for values of type `dyn ToBar` cannot be known at compilation time
   --> $DIR/dst-bad-assign-3.rs:33:5
diff --git a/tests/ui/dst/dst-bad-assign.stderr b/tests/ui/dst/dst-bad-assign.stderr
index d8d1057876f..f935d27e96e 100644
--- a/tests/ui/dst/dst-bad-assign.stderr
+++ b/tests/ui/dst/dst-bad-assign.stderr
@@ -8,6 +8,7 @@ LL |     f5.ptr = Bar1 {f: 36};
    |
    = note: expected trait object `dyn ToBar`
                     found struct `Bar1`
+   = help: `Bar1` implements `ToBar` so you could box the found value and coerce it to the trait object `Box<dyn ToBar>`, you will have to change the expected type as well
 
 error[E0277]: the size for values of type `dyn ToBar` cannot be known at compilation time
   --> $DIR/dst-bad-assign.rs:35:5
diff --git a/tests/ui/dyn-star/no-implicit-dyn-star.stderr b/tests/ui/dyn-star/no-implicit-dyn-star.stderr
index 06c7bcc5748..bea334a8a69 100644
--- a/tests/ui/dyn-star/no-implicit-dyn-star.stderr
+++ b/tests/ui/dyn-star/no-implicit-dyn-star.stderr
@@ -8,6 +8,7 @@ LL |     dyn_star_foreign::require_dyn_star_display(1usize);
    |
    = note: expected trait object `(dyn* std::fmt::Display + 'static)`
                       found type `usize`
+   = help: `usize` implements `Display`, `#[feature(dyn_star)]` is likely not enabled; that feature it is currently incomplete
 note: function defined here
   --> $DIR/auxiliary/dyn-star-foreign.rs:6:8
    |
diff --git a/tests/ui/enum-discriminant/issue-72554.rs b/tests/ui/enum-discriminant/issue-72554.rs
index 54f7e9ac592..1fe9a5f4faa 100644
--- a/tests/ui/enum-discriminant/issue-72554.rs
+++ b/tests/ui/enum-discriminant/issue-72554.rs
@@ -3,6 +3,7 @@ use std::collections::BTreeSet;
 #[derive(Hash)]
 pub enum ElemDerived {
     //~^ ERROR recursive type `ElemDerived` has infinite size
+    //~| ERROR cycle detected
     A(ElemDerived)
 }
 
diff --git a/tests/ui/enum-discriminant/issue-72554.stderr b/tests/ui/enum-discriminant/issue-72554.stderr
index 381f24d351e..648680c6031 100644
--- a/tests/ui/enum-discriminant/issue-72554.stderr
+++ b/tests/ui/enum-discriminant/issue-72554.stderr
@@ -3,7 +3,7 @@ error[E0072]: recursive type `ElemDerived` has infinite size
    |
 LL | pub enum ElemDerived {
    | ^^^^^^^^^^^^^^^^^^^^
-LL |
+...
 LL |     A(ElemDerived)
    |       ----------- recursive without indirection
    |
@@ -12,6 +12,21 @@ help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to break the cycle
 LL |     A(Box<ElemDerived>)
    |       ++++           +
 
-error: aborting due to 1 previous error
+error[E0391]: cycle detected when computing drop-check constraints for `ElemDerived`
+  --> $DIR/issue-72554.rs:4:1
+   |
+LL | pub enum ElemDerived {
+   | ^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: ...which immediately requires computing drop-check constraints for `ElemDerived` again
+note: cycle used when computing drop-check constraints for `Elem`
+  --> $DIR/issue-72554.rs:11:1
+   |
+LL | pub enum Elem {
+   | ^^^^^^^^^^^^^
+   = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
+
+error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0072`.
+Some errors have detailed explanations: E0072, E0391.
+For more information about an error, try `rustc --explain E0072`.
diff --git a/tests/ui/for-loop-while/issue-69841.rs b/tests/ui/for-loop-while/issue-69841.rs
index 1aca16ca804..942b99b742b 100644
--- a/tests/ui/for-loop-while/issue-69841.rs
+++ b/tests/ui/for-loop-while/issue-69841.rs
@@ -2,7 +2,6 @@
 // LLVM bug which needed a fix to be backported.
 
 // run-pass
-// no-system-llvm
 
 fn main() {
     let buffer = [49u8, 10];
diff --git a/tests/ui/generic-associated-types/issue-79422.extended.stderr b/tests/ui/generic-associated-types/issue-79422.extended.stderr
index 14492266cda..ae1526296a7 100644
--- a/tests/ui/generic-associated-types/issue-79422.extended.stderr
+++ b/tests/ui/generic-associated-types/issue-79422.extended.stderr
@@ -27,6 +27,7 @@ LL |     type VRefCont<'a> = &'a V where Self: 'a;
    |                         ^^^^^
    = note: expected trait object `(dyn RefCont<'_, u8> + 'static)`
                  found reference `&u8`
+   = help: `&u8` implements `RefCont` so you could box the found value and coerce it to the trait object `Box<dyn RefCont>`, you will have to change the expected type as well
    = note: required for the cast from `Box<BTreeMap<u8, u8>>` to `Box<dyn MapLike<u8, u8, VRefCont = (dyn RefCont<'_, u8> + 'static)>>`
 
 error: aborting due to 2 previous errors
diff --git a/tests/ui/impl-trait/dyn-impl-type-mismatch.rs b/tests/ui/impl-trait/dyn-impl-type-mismatch.rs
new file mode 100644
index 00000000000..c6170abb582
--- /dev/null
+++ b/tests/ui/impl-trait/dyn-impl-type-mismatch.rs
@@ -0,0 +1,18 @@
+trait Trait {}
+struct Struct;
+impl Trait for Struct {}
+fn foo() -> impl Trait {
+    Struct
+}
+fn main() {
+    let a: Box<dyn Trait> = if true {
+        Box::new(Struct)
+    } else {
+        foo() //~ ERROR E0308
+    };
+    let a: dyn Trait = if true {
+        Struct //~ ERROR E0308
+    } else {
+        foo() //~ ERROR E0308
+    };
+}
diff --git a/tests/ui/impl-trait/dyn-impl-type-mismatch.stderr b/tests/ui/impl-trait/dyn-impl-type-mismatch.stderr
new file mode 100644
index 00000000000..ddbdaf3eb4b
--- /dev/null
+++ b/tests/ui/impl-trait/dyn-impl-type-mismatch.stderr
@@ -0,0 +1,43 @@
+error[E0308]: mismatched types
+  --> $DIR/dyn-impl-type-mismatch.rs:11:9
+   |
+LL | fn foo() -> impl Trait {
+   |             ---------- the found opaque type
+...
+LL |         foo()
+   |         ^^^^^ expected `Box<dyn Trait>`, found opaque type
+   |
+   = note:   expected struct `Box<dyn Trait>`
+           found opaque type `impl Trait`
+   = note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html
+help: store this in the heap by calling `Box::new`
+   |
+LL |         Box::new(foo())
+   |         +++++++++     +
+
+error[E0308]: mismatched types
+  --> $DIR/dyn-impl-type-mismatch.rs:14:9
+   |
+LL |         Struct
+   |         ^^^^^^ expected `dyn Trait`, found `Struct`
+   |
+   = note: expected trait object `dyn Trait`
+                    found struct `Struct`
+   = help: `Struct` implements `Trait` so you could box the found value and coerce it to the trait object `Box<dyn Trait>`, you will have to change the expected type as well
+
+error[E0308]: mismatched types
+  --> $DIR/dyn-impl-type-mismatch.rs:16:9
+   |
+LL | fn foo() -> impl Trait {
+   |             ---------- the found opaque type
+...
+LL |         foo()
+   |         ^^^^^ expected `dyn Trait`, found opaque type
+   |
+   = note: expected trait object `dyn Trait`
+               found opaque type `impl Trait`
+   = help: you can box the `impl Trait` to coerce it to `Box<dyn Trait>`, but you'll have to change the expected type as well
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr b/tests/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr
index 4a52f82540d..9cc199d1e0e 100644
--- a/tests/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr
+++ b/tests/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr
@@ -6,6 +6,7 @@ LL | fn fuz() -> (usize, Trait) { (42, Struct) }
    |
    = note: expected trait object `(dyn Trait + 'static)`
                     found struct `Struct`
+   = help: `Struct` implements `Trait` so you could box the found value and coerce it to the trait object `Box<dyn Trait>`, you will have to change the expected type as well
 
 error[E0277]: the size for values of type `(dyn Trait + 'static)` cannot be known at compilation time
   --> $DIR/dyn-trait-return-should-be-impl-trait.rs:7:13
@@ -27,6 +28,7 @@ LL | fn bar() -> (usize, dyn Trait) { (42, Struct) }
    |
    = note: expected trait object `(dyn Trait + 'static)`
                     found struct `Struct`
+   = help: `Struct` implements `Trait` so you could box the found value and coerce it to the trait object `Box<dyn Trait>`, you will have to change the expected type as well
 
 error[E0277]: the size for values of type `(dyn Trait + 'static)` cannot be known at compilation time
   --> $DIR/dyn-trait-return-should-be-impl-trait.rs:10:13
diff --git a/tests/ui/issue-76387-llvm-miscompile.rs b/tests/ui/issue-76387-llvm-miscompile.rs
index a9b4686c970..a7fc9da6339 100644
--- a/tests/ui/issue-76387-llvm-miscompile.rs
+++ b/tests/ui/issue-76387-llvm-miscompile.rs
@@ -1,4 +1,3 @@
-// no-system-llvm
 // compile-flags: -C opt-level=3
 // aux-build: issue-76387.rs
 // run-pass
diff --git a/tests/ui/methods/issues/issue-61525.stderr b/tests/ui/methods/issues/issue-61525.stderr
index a329b52e373..2670a3e4755 100644
--- a/tests/ui/methods/issues/issue-61525.stderr
+++ b/tests/ui/methods/issues/issue-61525.stderr
@@ -27,6 +27,7 @@ LL |         1.query::<dyn ToString>("")
    |
    = note: expected trait object `dyn ToString`
                  found reference `&'static str`
+   = help: `&'static str` implements `ToString` so you could box the found value and coerce it to the trait object `Box<dyn ToString>`, you will have to change the expected type as well
 note: method defined here
   --> $DIR/issue-61525.rs:2:8
    |
diff --git a/tests/ui/privacy/private-type-in-interface.rs b/tests/ui/privacy/private-type-in-interface.rs
index 39e0bf23cac..9f55127fd16 100644
--- a/tests/ui/privacy/private-type-in-interface.rs
+++ b/tests/ui/privacy/private-type-in-interface.rs
@@ -26,6 +26,7 @@ type A = <m::Alias as m::Trait>::X; //~ ERROR type `Priv` is private
 trait Tr2<T> {}
 impl<T> Tr2<T> for u8 {}
 fn g() -> impl Tr2<m::Alias> { 0 } //~ ERROR type `Priv` is private
+                                   //~| ERROR type `Priv` is private
 fn g_ext() -> impl Tr2<ext::Alias> { 0 } //~ ERROR type `ext::Priv` is private
-
+                                         //~| ERROR type `ext::Priv` is private
 fn main() {}
diff --git a/tests/ui/privacy/private-type-in-interface.stderr b/tests/ui/privacy/private-type-in-interface.stderr
index 03225d84fdb..a5e80d6962d 100644
--- a/tests/ui/privacy/private-type-in-interface.stderr
+++ b/tests/ui/privacy/private-type-in-interface.stderr
@@ -46,11 +46,23 @@ error: type `Priv` is private
 LL | fn g() -> impl Tr2<m::Alias> { 0 }
    |           ^^^^^^^^^^^^^^^^^^ private type
 
+error: type `Priv` is private
+  --> $DIR/private-type-in-interface.rs:28:16
+   |
+LL | fn g() -> impl Tr2<m::Alias> { 0 }
+   |                ^^^^^^^^^^^^^ private type
+
 error: type `ext::Priv` is private
-  --> $DIR/private-type-in-interface.rs:29:15
+  --> $DIR/private-type-in-interface.rs:30:15
    |
 LL | fn g_ext() -> impl Tr2<ext::Alias> { 0 }
    |               ^^^^^^^^^^^^^^^^^^^^ private type
 
-error: aborting due to 9 previous errors
+error: type `ext::Priv` is private
+  --> $DIR/private-type-in-interface.rs:30:20
+   |
+LL | fn g_ext() -> impl Tr2<ext::Alias> { 0 }
+   |                    ^^^^^^^^^^^^^^^ private type
+
+error: aborting due to 11 previous errors
 
diff --git a/tests/ui/repeat-expr/repeat-to-run-dtor-twice.stderr b/tests/ui/repeat-expr/repeat-to-run-dtor-twice.stderr
index f3fe8c10c02..1f7487e68be 100644
--- a/tests/ui/repeat-expr/repeat-to-run-dtor-twice.stderr
+++ b/tests/ui/repeat-expr/repeat-to-run-dtor-twice.stderr
@@ -6,7 +6,7 @@ LL |     let _ = [ a; 5 ];
    |
    = note: the `Copy` trait is required because this value will be copied for each element of the array
    = help: consider using `core::array::from_fn` to initialize the array
-   = help: see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html# for more information
+   = help: see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html for more information
 help: consider annotating `Foo` with `#[derive(Copy)]`
    |
 LL + #[derive(Copy)]
diff --git a/tests/ui/rfcs/rfc-2632-const-trait-impl/specializing-constness-2.stderr b/tests/ui/rfcs/rfc-2632-const-trait-impl/specializing-constness-2.stderr
index e5b9493b3ce..5210a694201 100644
--- a/tests/ui/rfcs/rfc-2632-const-trait-impl/specializing-constness-2.stderr
+++ b/tests/ui/rfcs/rfc-2632-const-trait-impl/specializing-constness-2.stderr
@@ -7,16 +7,6 @@ LL | impl<T: Default> A for T {
 LL | impl<T: Default + ~const Sup> const A for T {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation
 
-error[E0308]: mismatched types
-  --> $DIR/specializing-constness-2.rs:27:5
-   |
-LL |     <T as A>::a();
-   |     ^^^^^^^^^^^^^ expected `host`, found `true`
-   |
-   = note: expected constant `host`
-              found constant `true`
-
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 
-Some errors have detailed explanations: E0119, E0308.
-For more information about an error, try `rustc --explain E0119`.
+For more information about this error, try `rustc --explain E0119`.
diff --git a/tests/ui/specialization/min_specialization/bad-const-wf-doesnt-specialize.rs b/tests/ui/specialization/min_specialization/bad-const-wf-doesnt-specialize.rs
index 8ceecd801d3..a0ee7714417 100644
--- a/tests/ui/specialization/min_specialization/bad-const-wf-doesnt-specialize.rs
+++ b/tests/ui/specialization/min_specialization/bad-const-wf-doesnt-specialize.rs
@@ -6,7 +6,6 @@
 struct S<const L: usize>;
 
 impl<const N: i32> Copy for S<N> {}
-//~^ ERROR the constant `N` is not of type `usize`
 impl<const M: usize> Copy for S<M> {}
 //~^ ERROR: conflicting implementations of trait `Copy` for type `S<_>`
 
diff --git a/tests/ui/specialization/min_specialization/bad-const-wf-doesnt-specialize.stderr b/tests/ui/specialization/min_specialization/bad-const-wf-doesnt-specialize.stderr
index 3268a876733..2953bc95917 100644
--- a/tests/ui/specialization/min_specialization/bad-const-wf-doesnt-specialize.stderr
+++ b/tests/ui/specialization/min_specialization/bad-const-wf-doesnt-specialize.stderr
@@ -1,29 +1,11 @@
 error[E0119]: conflicting implementations of trait `Copy` for type `S<_>`
-  --> $DIR/bad-const-wf-doesnt-specialize.rs:10:1
+  --> $DIR/bad-const-wf-doesnt-specialize.rs:9:1
    |
 LL | impl<const N: i32> Copy for S<N> {}
    | -------------------------------- first implementation here
-LL |
 LL | impl<const M: usize> Copy for S<M> {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `S<_>`
 
-error: the constant `N` is not of type `usize`
-  --> $DIR/bad-const-wf-doesnt-specialize.rs:8:29
-   |
-LL | impl<const N: i32> Copy for S<N> {}
-   |                             ^^^^ expected `usize`, found `i32`
-   |
-note: required for `S<N>` to implement `Clone`
-  --> $DIR/bad-const-wf-doesnt-specialize.rs:5:10
-   |
-LL | #[derive(Clone)]
-   |          ^^^^^
-LL | struct S<const L: usize>;
-   |          ----- unsatisfied trait bound introduced in this `derive` macro
-note: required by a bound in `Copy`
-  --> $SRC_DIR/core/src/marker.rs:LL:COL
-   = note: this error originates in the derive macro `Clone` (in Nightly builds, run with -Z macro-backtrace for more info)
-
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0119`.
diff --git a/tests/ui/trait-bounds/issue-119530-sugg-from-fn.stderr b/tests/ui/trait-bounds/issue-119530-sugg-from-fn.stderr
index f394c4cf027..9217637901b 100644
--- a/tests/ui/trait-bounds/issue-119530-sugg-from-fn.stderr
+++ b/tests/ui/trait-bounds/issue-119530-sugg-from-fn.stderr
@@ -6,7 +6,7 @@ LL |     let string_arr = [foo(); 64];
    |
    = note: the `Copy` trait is required because this value will be copied for each element of the array
    = help: consider using `core::array::from_fn` to initialize the array
-   = help: see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html# for more information
+   = help: see https://doc.rust-lang.org/stable/std/array/fn.from_fn.html for more information
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/typeck/typeck_type_placeholder_item.rs b/tests/ui/typeck/typeck_type_placeholder_item.rs
index f6d1fb6a23d..4eba14f5a93 100644
--- a/tests/ui/typeck/typeck_type_placeholder_item.rs
+++ b/tests/ui/typeck/typeck_type_placeholder_item.rs
@@ -198,7 +198,6 @@ trait Qux {
     //~^ ERROR the placeholder `_` is not allowed within types on item signatures for associated types
 }
 impl Qux for Struct {
-    //~^ ERROR: not all trait items implemented, missing: `F`
     type A = _;
     //~^ ERROR the placeholder `_` is not allowed within types on item signatures for associated types
     type B = _;
diff --git a/tests/ui/typeck/typeck_type_placeholder_item.stderr b/tests/ui/typeck/typeck_type_placeholder_item.stderr
index bfcc76c1dae..a4325b01f02 100644
--- a/tests/ui/typeck/typeck_type_placeholder_item.stderr
+++ b/tests/ui/typeck/typeck_type_placeholder_item.stderr
@@ -29,7 +29,7 @@ LL | struct BadStruct2<_, T>(_, T);
    |                   ^ expected identifier, found reserved identifier
 
 error: associated constant in `impl` without body
-  --> $DIR/typeck_type_placeholder_item.rs:206:5
+  --> $DIR/typeck_type_placeholder_item.rs:205:5
    |
 LL |     const C: _;
    |     ^^^^^^^^^^-
@@ -411,7 +411,7 @@ LL | type Y = impl Trait<_>;
    |                     ^ not allowed in type signatures
 
 error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
-  --> $DIR/typeck_type_placeholder_item.rs:217:31
+  --> $DIR/typeck_type_placeholder_item.rs:216:31
    |
 LL | fn value() -> Option<&'static _> {
    |               ----------------^-
@@ -420,7 +420,7 @@ LL | fn value() -> Option<&'static _> {
    |               help: replace with the correct return type: `Option<&'static u8>`
 
 error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
-  --> $DIR/typeck_type_placeholder_item.rs:222:10
+  --> $DIR/typeck_type_placeholder_item.rs:221:10
    |
 LL | const _: Option<_> = map(value);
    |          ^^^^^^^^^
@@ -429,7 +429,7 @@ LL | const _: Option<_> = map(value);
    |          help: replace with the correct type: `Option<u8>`
 
 error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
-  --> $DIR/typeck_type_placeholder_item.rs:225:31
+  --> $DIR/typeck_type_placeholder_item.rs:224:31
    |
 LL | fn evens_squared(n: usize) -> _ {
    |                               ^
@@ -438,13 +438,13 @@ LL | fn evens_squared(n: usize) -> _ {
    |                               help: replace with an appropriate return type: `impl Iterator<Item = usize>`
 
 error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
-  --> $DIR/typeck_type_placeholder_item.rs:230:10
+  --> $DIR/typeck_type_placeholder_item.rs:229:10
    |
 LL | const _: _ = (1..10).filter(|x| x % 2 == 0).map(|x| x * x);
    |          ^ not allowed in type signatures
    |
-note: however, the inferred type `Map<Filter<Range<i32>, {closure@typeck_type_placeholder_item.rs:230:29}>, {closure@typeck_type_placeholder_item.rs:230:49}>` cannot be named
-  --> $DIR/typeck_type_placeholder_item.rs:230:14
+note: however, the inferred type `Map<Filter<Range<i32>, {closure@typeck_type_placeholder_item.rs:229:29}>, {closure@typeck_type_placeholder_item.rs:229:49}>` cannot be named
+  --> $DIR/typeck_type_placeholder_item.rs:229:14
    |
 LL | const _: _ = (1..10).filter(|x| x % 2 == 0).map(|x| x * x);
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -631,25 +631,25 @@ LL |         fn clone_from(&mut self, other: &FnTest9) { *self = FnTest9; }
    |                                         ~~~~~~~~
 
 error[E0121]: the placeholder `_` is not allowed within types on item signatures for associated types
-  --> $DIR/typeck_type_placeholder_item.rs:202:14
+  --> $DIR/typeck_type_placeholder_item.rs:201:14
    |
 LL |     type A = _;
    |              ^ not allowed in type signatures
 
 error[E0121]: the placeholder `_` is not allowed within types on item signatures for associated types
-  --> $DIR/typeck_type_placeholder_item.rs:204:14
+  --> $DIR/typeck_type_placeholder_item.rs:203:14
    |
 LL |     type B = _;
    |              ^ not allowed in type signatures
 
 error[E0121]: the placeholder `_` is not allowed within types on item signatures for associated constants
-  --> $DIR/typeck_type_placeholder_item.rs:206:14
+  --> $DIR/typeck_type_placeholder_item.rs:205:14
    |
 LL |     const C: _;
    |              ^ not allowed in type signatures
 
 error[E0121]: the placeholder `_` is not allowed within types on item signatures for associated constants
-  --> $DIR/typeck_type_placeholder_item.rs:209:14
+  --> $DIR/typeck_type_placeholder_item.rs:208:14
    |
 LL |     const D: _ = 42;
    |              ^
@@ -657,16 +657,7 @@ LL |     const D: _ = 42;
    |              not allowed in type signatures
    |              help: replace with the correct type: `i32`
 
-error[E0046]: not all trait items implemented, missing: `F`
-  --> $DIR/typeck_type_placeholder_item.rs:200:1
-   |
-LL |     type F: std::ops::Fn(_);
-   |     ----------------------- `F` from trait
-...
-LL | impl Qux for Struct {
-   | ^^^^^^^^^^^^^^^^^^^ missing `F` in implementation
-
-error: aborting due to 72 previous errors
+error: aborting due to 71 previous errors
 
-Some errors have detailed explanations: E0046, E0121, E0282, E0403.
-For more information about an error, try `rustc --explain E0046`.
+Some errors have detailed explanations: E0121, E0282, E0403.
+For more information about an error, try `rustc --explain E0121`.
diff --git a/triagebot.toml b/triagebot.toml
index 36e58f0f9d8..264f6efd982 100644
--- a/triagebot.toml
+++ b/triagebot.toml
@@ -646,6 +646,7 @@ compiler-team = [
     "@estebank",
     "@oli-obk",
     "@wesleywiser",
+    "@michaelwoerister",
 ]
 compiler-team-contributors = [
     "@TaKO8Ki",
@@ -738,6 +739,10 @@ ast_lowering = [
     "@estebank",
     "@spastorino",
 ]
+debuginfo = [
+    "@michaelwoerister",
+    "@davidtwco"
+]
 fallback = [
     "@Mark-Simulacrum"
 ]
@@ -761,66 +766,71 @@ project-stable-mir = [
 ]
 
 [assign.owners]
-"/.github/workflows" =                       ["infra-ci"]
-"/Cargo.lock" =                              ["@Mark-Simulacrum"]
-"/Cargo.toml" =                              ["@Mark-Simulacrum"]
-"/compiler" =                                ["compiler"]
-"/compiler/rustc_arena" =                    ["compiler", "arena"]
-"/compiler/rustc_ast" =                      ["compiler", "parser"]
-"/compiler/rustc_ast_lowering" =             ["compiler", "ast_lowering"]
-"/compiler/rustc_hir_analysis" =             ["compiler", "types"]
-"/compiler/rustc_lexer" =                    ["compiler", "lexer"]
-"/compiler/rustc_llvm" =                     ["@cuviper"]
-"/compiler/rustc_middle/src/mir" =           ["compiler", "mir"]
-"/compiler/rustc_middle/src/traits" =        ["compiler", "types"]
-"/compiler/rustc_middle/src/ty" =            ["compiler", "types"]
-"/compiler/rustc_const_eval/src/interpret" = ["compiler", "mir"]
-"/compiler/rustc_const_eval/src/transform" = ["compiler", "mir-opt"]
-"/compiler/rustc_mir_build/src/build" =      ["compiler", "mir"]
-"/compiler/rustc_smir" =                     ["project-stable-mir"]
-"/compiler/rustc_parse" =                    ["compiler", "parser"]
-"/compiler/rustc_parse/src/lexer" =          ["compiler", "lexer"]
-"/compiler/rustc_query_impl" =               ["compiler", "query-system"]
-"/compiler/rustc_query_system" =             ["compiler", "query-system"]
-"/compiler/rustc_trait_selection" =          ["compiler", "types"]
-"/compiler/rustc_traits" =                   ["compiler", "types"]
-"/compiler/rustc_type_ir" =                  ["compiler", "types"]
-"/compiler/stable_mir" =                     ["project-stable-mir"]
-"/library/alloc" =                           ["libs"]
-"/library/core" =                            ["libs"]
-"/library/panic_abort" =                     ["libs"]
-"/library/panic_unwind" =                    ["libs"]
-"/library/proc_macro" =                      ["@petrochenkov"]
-"/library/std" =                             ["libs"]
-"/library/std/src/sys/pal/windows" =         ["@ChrisDenton", "@thomcc"]
-"/library/stdarch" =                         ["libs"]
-"/library/test" =                            ["libs"]
-"/src/bootstrap" =                           ["bootstrap"]
-"/src/ci" =                                  ["infra-ci"]
-"/src/doc" =                                 ["docs"]
-"/src/doc/book" =                            ["@ehuss"]
-"/src/doc/edition-guide" =                   ["@ehuss"]
-"/src/doc/embedded-book" =                   ["@ehuss"]
-"/src/doc/nomicon" =                         ["@ehuss"]
-"/src/doc/reference" =                       ["@ehuss"]
-"/src/doc/rust-by-example" =                 ["@ehuss"]
-"/src/doc/rustc-dev-guide" =                 ["@ehuss"]
-"/src/doc/rustdoc" =                         ["rustdoc"]
-"/src/doc/style-guide" =                     ["style-team"]
-"/src/etc" =                                 ["@Mark-Simulacrum"]
-"/src/librustdoc" =                          ["rustdoc"]
-"/src/llvm-project" =                        ["@cuviper"]
-"/src/rustdoc-json-types" =                  ["rustdoc"]
-"/src/stage0.json" =                         ["bootstrap"]
-"/tests/ui" =                                ["compiler"]
-"/src/tools/cargo" =                         ["@ehuss", "@joshtriplett"]
-"/src/tools/compiletest" =                   ["bootstrap", "@wesleywiser", "@oli-obk", "@compiler-errors"]
-"/src/tools/linkchecker" =                   ["@ehuss"]
-"/src/tools/rust-installer" =                ["bootstrap"]
-"/src/tools/rustbook" =                      ["@ehuss"]
-"/src/tools/rustdoc" =                       ["rustdoc"]
-"/src/tools/rustdoc-js" =                    ["rustdoc"]
-"/src/tools/rustdoc-themes" =                ["rustdoc"]
-"/src/tools/tidy" =                          ["bootstrap"]
-"/src/tools/x" =                             ["bootstrap"]
-"/src/tools/rustdoc-gui-test" =              ["bootstrap", "@onur-ozkan"]
+"/.github/workflows" =                                   ["infra-ci"]
+"/Cargo.lock" =                                          ["@Mark-Simulacrum"]
+"/Cargo.toml" =                                          ["@Mark-Simulacrum"]
+"/compiler" =                                            ["compiler"]
+"/compiler/rustc_arena" =                                ["compiler", "arena"]
+"/compiler/rustc_ast" =                                  ["compiler", "parser"]
+"/compiler/rustc_ast_lowering" =                         ["compiler", "ast_lowering"]
+"/compiler/rustc_data_structures/src/stable_hasher.rs" = ["compiler", "incremental"]
+"/compiler/rustc_hir_analysis" =                         ["compiler", "types"]
+"/compiler/rustc_incremental" =                          ["compiler", "incremental"]
+"/compiler/rustc_lexer" =                                ["compiler", "lexer"]
+"/compiler/rustc_llvm" =                                 ["@cuviper"]
+"/compiler/rustc_codegen_llvm/src/debuginfo" =           ["compiler", "debuginfo"]
+"/compiler/rustc_middle/src/mir" =                       ["compiler", "mir"]
+"/compiler/rustc_middle/src/traits" =                    ["compiler", "types"]
+"/compiler/rustc_middle/src/ty" =                        ["compiler", "types"]
+"/compiler/rustc_const_eval/src/interpret" =             ["compiler", "mir"]
+"/compiler/rustc_const_eval/src/transform" =             ["compiler", "mir-opt"]
+"/compiler/rustc_mir_build/src/build" =                  ["compiler", "mir"]
+"/compiler/rustc_smir" =                                 ["project-stable-mir"]
+"/compiler/rustc_parse" =                                ["compiler", "parser"]
+"/compiler/rustc_parse/src/lexer" =                      ["compiler", "lexer"]
+"/compiler/rustc_query_impl" =                           ["compiler", "query-system"]
+"/compiler/rustc_query_system" =                         ["compiler", "query-system"]
+"/compiler/rustc_query_system/src/dep_graph" =           ["compiler", "incremental", "query-system"]
+"/compiler/rustc_query_system/src/ich" =                 ["compiler", "incremental", "query-system"]
+"/compiler/rustc_trait_selection" =                      ["compiler", "types"]
+"/compiler/rustc_traits" =                               ["compiler", "types"]
+"/compiler/rustc_type_ir" =                              ["compiler", "types"]
+"/compiler/stable_mir" =                                 ["project-stable-mir"]
+"/library/alloc" =                                       ["libs"]
+"/library/core" =                                        ["libs"]
+"/library/panic_abort" =                                 ["libs"]
+"/library/panic_unwind" =                                ["libs"]
+"/library/proc_macro" =                                  ["@petrochenkov"]
+"/library/std" =                                         ["libs"]
+"/library/std/src/sys/pal/windows" =                     ["@ChrisDenton", "@thomcc"]
+"/library/stdarch" =                                     ["libs"]
+"/library/test" =                                        ["libs"]
+"/src/bootstrap" =                                       ["bootstrap"]
+"/src/ci" =                                              ["infra-ci"]
+"/src/doc" =                                             ["docs"]
+"/src/doc/book" =                                        ["@ehuss"]
+"/src/doc/edition-guide" =                               ["@ehuss"]
+"/src/doc/embedded-book" =                               ["@ehuss"]
+"/src/doc/nomicon" =                                     ["@ehuss"]
+"/src/doc/reference" =                                   ["@ehuss"]
+"/src/doc/rust-by-example" =                             ["@ehuss"]
+"/src/doc/rustc-dev-guide" =                             ["@ehuss"]
+"/src/doc/rustdoc" =                                     ["rustdoc"]
+"/src/doc/style-guide" =                                 ["style-team"]
+"/src/etc" =                                             ["@Mark-Simulacrum"]
+"/src/librustdoc" =                                      ["rustdoc"]
+"/src/llvm-project" =                                    ["@cuviper"]
+"/src/rustdoc-json-types" =                              ["rustdoc"]
+"/src/stage0.json" =                                     ["bootstrap"]
+"/tests/ui" =                                            ["compiler"]
+"/src/tools/cargo" =                                     ["@ehuss", "@joshtriplett"]
+"/src/tools/compiletest" =                               ["bootstrap", "@wesleywiser", "@oli-obk", "@compiler-errors"]
+"/src/tools/linkchecker" =                               ["@ehuss"]
+"/src/tools/rust-installer" =                            ["bootstrap"]
+"/src/tools/rustbook" =                                  ["@ehuss"]
+"/src/tools/rustdoc" =                                   ["rustdoc"]
+"/src/tools/rustdoc-js" =                                ["rustdoc"]
+"/src/tools/rustdoc-themes" =                            ["rustdoc"]
+"/src/tools/tidy" =                                      ["bootstrap"]
+"/src/tools/x" =                                         ["bootstrap"]
+"/src/tools/rustdoc-gui-test" =                          ["bootstrap", "@onur-ozkan"]