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-rw-r--r--.gitmodules2
-rw-r--r--Cargo.lock1
-rw-r--r--compiler/rustc_ast_lowering/src/lib.rs32
-rw-r--r--compiler/rustc_ast_lowering/src/path.rs19
-rw-r--r--compiler/rustc_codegen_ssa/src/back/link.rs2
-rw-r--r--compiler/rustc_const_eval/src/interpret/machine.rs16
-rw-r--r--compiler/rustc_const_eval/src/interpret/step.rs39
-rw-r--r--compiler/rustc_driver/src/lib.rs9
-rw-r--r--compiler/rustc_expand/src/base.rs2
-rw-r--r--compiler/rustc_expand/src/expand.rs2
-rw-r--r--compiler/rustc_hir/src/hir.rs2
-rw-r--r--compiler/rustc_hir/src/tests.rs38
-rw-r--r--compiler/rustc_hir_analysis/src/collect/generics_of.rs16
-rw-r--r--compiler/rustc_hir_typeck/src/check.rs3
-rw-r--r--compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs3
-rw-r--r--compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs5
-rw-r--r--compiler/rustc_hir_typeck/src/lib.rs32
-rw-r--r--compiler/rustc_incremental/src/persist/fs.rs5
-rw-r--r--compiler/rustc_infer/src/infer/error_reporting/mod.rs843
-rw-r--r--compiler/rustc_infer/src/infer/error_reporting/note.rs2
-rw-r--r--compiler/rustc_infer/src/infer/error_reporting/note_region.rs427
-rw-r--r--compiler/rustc_infer/src/infer/error_reporting/suggest.rs672
-rw-r--r--compiler/rustc_infer/src/infer/note.rs203
-rw-r--r--compiler/rustc_interface/src/passes.rs40
-rw-r--r--compiler/rustc_interface/src/queries.rs21
-rw-r--r--compiler/rustc_metadata/src/creader.rs6
-rw-r--r--compiler/rustc_metadata/src/fs.rs3
-rw-r--r--compiler/rustc_middle/src/mir/syntax.rs2
-rw-r--r--compiler/rustc_middle/src/ty/context.rs4
-rw-r--r--compiler/rustc_middle/src/ty/error.rs31
-rw-r--r--compiler/rustc_mir_transform/src/add_retag.rs53
-rw-r--r--compiler/rustc_mir_transform/src/generator.rs10
-rw-r--r--compiler/rustc_mir_transform/src/shim.rs10
-rw-r--r--compiler/rustc_resolve/src/lib.rs2
-rw-r--r--compiler/rustc_save_analysis/src/dump_visitor.rs6
-rw-r--r--compiler/rustc_save_analysis/src/lib.rs8
-rw-r--r--compiler/rustc_session/Cargo.toml1
-rw-r--r--compiler/rustc_session/src/errors.rs8
-rw-r--r--compiler/rustc_session/src/output.rs29
-rw-r--r--compiler/rustc_session/src/session.rs11
-rw-r--r--compiler/rustc_span/src/def_id.rs8
-rw-r--r--compiler/rustc_target/src/spec/wasm32_unknown_unknown.rs7
-rw-r--r--compiler/rustc_trait_selection/src/traits/mod.rs370
-rw-r--r--compiler/rustc_trait_selection/src/traits/select/confirmation.rs13
-rw-r--r--compiler/rustc_trait_selection/src/traits/structural_match.rs48
-rw-r--r--compiler/rustc_trait_selection/src/traits/util.rs10
-rw-r--r--compiler/rustc_trait_selection/src/traits/vtable.rs386
-rw-r--r--compiler/rustc_traits/src/codegen.rs (renamed from compiler/rustc_trait_selection/src/traits/codegen.rs)12
-rw-r--r--compiler/rustc_traits/src/lib.rs2
-rw-r--r--compiler/rustc_ty_utils/src/lib.rs2
-rw-r--r--compiler/rustc_ty_utils/src/structural_match.rs44
-rw-r--r--library/core/src/num/mod.rs4
-rw-r--r--library/core/src/slice/mod.rs18
-rw-r--r--library/std/src/sys/itron/condvar.rs4
-rw-r--r--library/std/src/sys/itron/mutex.rs2
-rw-r--r--library/std/src/sys/itron/thread.rs48
-rw-r--r--library/std/src/sys/solid/io.rs4
-rw-r--r--library/std/src/sys/solid/os.rs3
-rw-r--r--src/ci/docker/host-x86_64/dist-powerpc64le-linux/Dockerfile2
-rw-r--r--src/ci/docker/host-x86_64/x86_64-gnu-llvm-13/Dockerfile2
-rw-r--r--src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile2
-rw-r--r--src/librustdoc/config.rs5
-rw-r--r--src/librustdoc/html/render/mod.rs19
-rw-r--r--src/librustdoc/html/static/css/rustdoc.css51
-rw-r--r--src/librustdoc/html/static/css/themes/ayu.css1
-rw-r--r--src/librustdoc/html/static/css/themes/dark.css1
-rw-r--r--src/librustdoc/html/static/css/themes/light.css1
-rw-r--r--src/librustdoc/html/static/js/main.js2
-rw-r--r--src/librustdoc/html/static/js/scrape-examples.js32
-rw-r--r--src/librustdoc/html/static/scrape-examples-help.md5
-rw-r--r--src/librustdoc/lib.rs14
-rw-r--r--src/librustdoc/scrape_examples.rs10
m---------src/llvm-project0
-rw-r--r--src/test/mir-opt/inline/inline_retag.bar.Inline.after.mir4
-rw-r--r--src/test/mir-opt/retag.array_casts.SimplifyCfg-elaborate-drops.after.mir10
-rw-r--r--src/test/mir-opt/retag.core.ptr-drop_in_place.Test.SimplifyCfg-make_shim.after.mir1
-rw-r--r--src/test/mir-opt/retag.main-{closure#0}.SimplifyCfg-elaborate-drops.after.mir1
-rw-r--r--src/test/mir-opt/retag.main.SimplifyCfg-elaborate-drops.after.mir11
-rw-r--r--src/test/mir-opt/retag.{impl#0}-foo.SimplifyCfg-elaborate-drops.after.mir2
-rw-r--r--src/test/run-make-fulldeps/hotplug_codegen_backend/the_backend.rs2
-rw-r--r--src/test/run-make/coverage-reports/Makefile2
-rw-r--r--src/test/rustdoc-gui/basic.goml4
-rw-r--r--src/test/rustdoc-gui/docblock-table.goml47
-rw-r--r--src/test/rustdoc-gui/scrape-examples-button-focus.goml2
-rw-r--r--src/test/rustdoc-gui/scrape-examples-toggle.goml14
-rw-r--r--src/test/rustdoc-gui/src/test_docs/lib.rs3
-rw-r--r--src/test/rustdoc-ui/const-evalutation-ice.rs (renamed from src/test/rustdoc/const-evalutation-ice.rs)3
-rw-r--r--src/test/rustdoc-ui/const-evalutation-ice.stderr9
-rw-r--r--src/test/ui/async-await/in-trait/nested-rpit.rs17
-rw-r--r--src/test/ui/diagnostic-width/long-E0308.rs86
-rw-r--r--src/test/ui/diagnostic-width/long-E0308.stderr80
-rw-r--r--src/test/ui/error-codes/E0275.stderr2
-rw-r--r--src/test/ui/feature-gates/feature-gate-impl_trait_in_fn_trait_return.stderr6
-rw-r--r--src/test/ui/issues/issue-20413.stderr10
-rw-r--r--src/test/ui/issues/issue-23122-2.stderr2
-rw-r--r--src/test/ui/recursion/issue-83150.stderr2
-rw-r--r--src/test/ui/regions/issue-102374.rs1
-rw-r--r--src/test/ui/regions/issue-102374.stderr5
-rw-r--r--src/test/ui/traits/issue-91949-hangs-on-recursion.stderr2
-rw-r--r--src/tools/miri/src/borrow_tracker/mod.rs13
-rw-r--r--src/tools/miri/src/borrow_tracker/stacked_borrows/diagnostics.rs4
-rw-r--r--src/tools/miri/src/borrow_tracker/stacked_borrows/mod.rs369
-rw-r--r--src/tools/miri/src/diagnostics.rs10
-rw-r--r--src/tools/miri/src/machine.rs22
104 files changed, 2775 insertions, 1723 deletions
diff --git a/.gitmodules b/.gitmodules
index c8504937806..4011a6fa6b9 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -28,7 +28,7 @@
 [submodule "src/llvm-project"]
 	path = src/llvm-project
 	url = https://github.com/rust-lang/llvm-project.git
-	branch = rustc/15.0-2022-08-09
+	branch = rustc/15.0-2022-12-07
 [submodule "src/doc/embedded-book"]
 	path = src/doc/embedded-book
 	url = https://github.com/rust-embedded/book.git
diff --git a/Cargo.lock b/Cargo.lock
index 150a70341f5..844cf99b468 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4348,6 +4348,7 @@ dependencies = [
  "rustc_span",
  "rustc_target",
  "smallvec",
+ "termize",
  "tracing",
  "winapi",
 ]
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index 07558ca075d..4fa18907fcd 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -259,6 +259,8 @@ enum ImplTraitContext {
     },
     /// Impl trait in type aliases.
     TypeAliasesOpaqueTy,
+    /// `impl Trait` is unstably accepted in this position.
+    FeatureGated(ImplTraitPosition, Symbol),
     /// `impl Trait` is not accepted in this position.
     Disallowed(ImplTraitPosition),
 }
@@ -1372,17 +1374,15 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                         }
                         path
                     }
-                    ImplTraitContext::Disallowed(
-                        position @ (ImplTraitPosition::TraitReturn | ImplTraitPosition::ImplReturn),
-                    ) => {
+                    ImplTraitContext::FeatureGated(position, feature) => {
                         self.tcx
                             .sess
                             .create_feature_err(
                                 MisplacedImplTrait {
                                     span: t.span,
-                                    position: DiagnosticArgFromDisplay(&position),
+                                    position: DiagnosticArgFromDisplay(position),
                                 },
-                                sym::return_position_impl_trait_in_trait,
+                                *feature,
                             )
                             .emit();
                         hir::TyKind::Err
@@ -1390,7 +1390,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     ImplTraitContext::Disallowed(position) => {
                         self.tcx.sess.emit_err(MisplacedImplTrait {
                             span: t.span,
-                            position: DiagnosticArgFromDisplay(&position),
+                            position: DiagnosticArgFromDisplay(position),
                         });
                         hir::TyKind::Err
                     }
@@ -1739,14 +1739,14 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         } else {
             match &decl.output {
                 FnRetTy::Ty(ty) => {
-                    let mut context = if kind.return_impl_trait_allowed(self.tcx) {
+                    let context = if kind.return_impl_trait_allowed(self.tcx) {
                         let fn_def_id = self.local_def_id(fn_node_id);
                         ImplTraitContext::ReturnPositionOpaqueTy {
                             origin: hir::OpaqueTyOrigin::FnReturn(fn_def_id),
                             in_trait: matches!(kind, FnDeclKind::Trait),
                         }
                     } else {
-                        ImplTraitContext::Disallowed(match kind {
+                        let position = match kind {
                             FnDeclKind::Fn | FnDeclKind::Inherent => {
                                 unreachable!("fn should allow in-band lifetimes")
                             }
@@ -1755,9 +1755,16 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                             FnDeclKind::Pointer => ImplTraitPosition::PointerReturn,
                             FnDeclKind::Trait => ImplTraitPosition::TraitReturn,
                             FnDeclKind::Impl => ImplTraitPosition::ImplReturn,
-                        })
+                        };
+                        match kind {
+                            FnDeclKind::Trait | FnDeclKind::Impl => ImplTraitContext::FeatureGated(
+                                position,
+                                sym::return_position_impl_trait_in_trait,
+                            ),
+                            _ => ImplTraitContext::Disallowed(position),
+                        }
                     };
-                    hir::FnRetTy::Return(self.lower_ty(ty, &mut context))
+                    hir::FnRetTy::Return(self.lower_ty(ty, &context))
                 }
                 FnRetTy::Default(span) => hir::FnRetTy::DefaultReturn(self.lower_span(*span)),
             }
@@ -1938,7 +1945,10 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     output,
                     span,
                     if in_trait && !this.tcx.features().return_position_impl_trait_in_trait {
-                        ImplTraitContext::Disallowed(ImplTraitPosition::TraitReturn)
+                        ImplTraitContext::FeatureGated(
+                            ImplTraitPosition::TraitReturn,
+                            sym::return_position_impl_trait_in_trait,
+                        )
                     } else {
                         ImplTraitContext::ReturnPositionOpaqueTy {
                             origin: hir::OpaqueTyOrigin::FnReturn(fn_def_id),
diff --git a/compiler/rustc_ast_lowering/src/path.rs b/compiler/rustc_ast_lowering/src/path.rs
index 8d23c26e603..592fc5aa645 100644
--- a/compiler/rustc_ast_lowering/src/path.rs
+++ b/compiler/rustc_ast_lowering/src/path.rs
@@ -9,7 +9,7 @@ use rustc_ast::{self as ast, *};
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, PartialRes, Res};
 use rustc_hir::GenericArg;
-use rustc_span::symbol::{kw, Ident};
+use rustc_span::symbol::{kw, sym, Ident};
 use rustc_span::{BytePos, Span, DUMMY_SP};
 
 use smallvec::{smallvec, SmallVec};
@@ -352,11 +352,18 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             // fn f(_: impl Fn() -> impl Debug) -> impl Fn() -> impl Debug
             // //      disallowed --^^^^^^^^^^        allowed --^^^^^^^^^^
             // ```
-            FnRetTy::Ty(ty)
-                if matches!(itctx, ImplTraitContext::ReturnPositionOpaqueTy { .. })
-                    && self.tcx.features().impl_trait_in_fn_trait_return =>
-            {
-                self.lower_ty(&ty, itctx)
+            FnRetTy::Ty(ty) if matches!(itctx, ImplTraitContext::ReturnPositionOpaqueTy { .. }) => {
+                if self.tcx.features().impl_trait_in_fn_trait_return {
+                    self.lower_ty(&ty, itctx)
+                } else {
+                    self.lower_ty(
+                        &ty,
+                        &ImplTraitContext::FeatureGated(
+                            ImplTraitPosition::FnTraitReturn,
+                            sym::impl_trait_in_fn_trait_return,
+                        ),
+                    )
+                }
             }
             FnRetTy::Ty(ty) => {
                 self.lower_ty(&ty, &ImplTraitContext::Disallowed(ImplTraitPosition::FnTraitReturn))
diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index 540f15c89e9..882430694e1 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -102,7 +102,7 @@ pub fn link_binary<'a>(
                 sess,
                 crate_type,
                 outputs,
-                codegen_results.crate_info.local_crate_name.as_str(),
+                codegen_results.crate_info.local_crate_name,
             );
             match crate_type {
                 CrateType::Rlib => {
diff --git a/compiler/rustc_const_eval/src/interpret/machine.rs b/compiler/rustc_const_eval/src/interpret/machine.rs
index 88d25be6bd8..0604d5ee6fa 100644
--- a/compiler/rustc_const_eval/src/interpret/machine.rs
+++ b/compiler/rustc_const_eval/src/interpret/machine.rs
@@ -373,9 +373,21 @@ pub trait Machine<'mir, 'tcx>: Sized {
         Ok(())
     }
 
-    /// Executes a retagging operation.
+    /// Executes a retagging operation for a single pointer.
+    /// Returns the possibly adjusted pointer.
     #[inline]
-    fn retag(
+    fn retag_ptr_value(
+        _ecx: &mut InterpCx<'mir, 'tcx, Self>,
+        _kind: mir::RetagKind,
+        val: &ImmTy<'tcx, Self::Provenance>,
+    ) -> InterpResult<'tcx, ImmTy<'tcx, Self::Provenance>> {
+        Ok(val.clone())
+    }
+
+    /// Executes a retagging operation on a compound value.
+    /// Replaces all pointers stored in the given place.
+    #[inline]
+    fn retag_place_contents(
         _ecx: &mut InterpCx<'mir, 'tcx, Self>,
         _kind: mir::RetagKind,
         _place: &PlaceTy<'tcx, Self::Provenance>,
diff --git a/compiler/rustc_const_eval/src/interpret/step.rs b/compiler/rustc_const_eval/src/interpret/step.rs
index 60578246eed..81b44a49484 100644
--- a/compiler/rustc_const_eval/src/interpret/step.rs
+++ b/compiler/rustc_const_eval/src/interpret/step.rs
@@ -8,7 +8,7 @@ use rustc_middle::mir;
 use rustc_middle::mir::interpret::{InterpResult, Scalar};
 use rustc_middle::ty::layout::LayoutOf;
 
-use super::{InterpCx, Machine};
+use super::{ImmTy, InterpCx, Machine};
 
 /// Classify whether an operator is "left-homogeneous", i.e., the LHS has the
 /// same type as the result.
@@ -108,7 +108,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             // Stacked Borrows.
             Retag(kind, place) => {
                 let dest = self.eval_place(**place)?;
-                M::retag(self, *kind, &dest)?;
+                M::retag_place_contents(self, *kind, &dest)?;
             }
 
             Intrinsic(box ref intrinsic) => self.emulate_nondiverging_intrinsic(intrinsic)?,
@@ -247,10 +247,41 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 self.write_scalar(Scalar::from_machine_usize(len, self), &dest)?;
             }
 
-            AddressOf(_, place) | Ref(_, _, place) => {
+            Ref(_, borrow_kind, place) => {
                 let src = self.eval_place(place)?;
                 let place = self.force_allocation(&src)?;
-                self.write_immediate(place.to_ref(self), &dest)?;
+                let val = ImmTy::from_immediate(place.to_ref(self), dest.layout);
+                // A fresh reference was created, make sure it gets retagged.
+                let val = M::retag_ptr_value(
+                    self,
+                    if borrow_kind.allows_two_phase_borrow() {
+                        mir::RetagKind::TwoPhase
+                    } else {
+                        mir::RetagKind::Default
+                    },
+                    &val,
+                )?;
+                self.write_immediate(*val, &dest)?;
+            }
+
+            AddressOf(_, place) => {
+                // Figure out whether this is an addr_of of an already raw place.
+                let place_base_raw = if place.has_deref() {
+                    let ty = self.frame().body.local_decls[place.local].ty;
+                    ty.is_unsafe_ptr()
+                } else {
+                    // Not a deref, and thus not raw.
+                    false
+                };
+
+                let src = self.eval_place(place)?;
+                let place = self.force_allocation(&src)?;
+                let mut val = ImmTy::from_immediate(place.to_ref(self), dest.layout);
+                if !place_base_raw {
+                    // If this was not already raw, it needs retagging.
+                    val = M::retag_ptr_value(self, mir::RetagKind::Raw, &val)?;
+                }
+                self.write_immediate(*val, &dest)?;
             }
 
             NullaryOp(null_op, ty) => {
diff --git a/compiler/rustc_driver/src/lib.rs b/compiler/rustc_driver/src/lib.rs
index 22f87514dd8..f06ca5a0733 100644
--- a/compiler/rustc_driver/src/lib.rs
+++ b/compiler/rustc_driver/src/lib.rs
@@ -25,6 +25,7 @@ use rustc_data_structures::sync::SeqCst;
 use rustc_errors::registry::{InvalidErrorCode, Registry};
 use rustc_errors::{ErrorGuaranteed, PResult};
 use rustc_feature::find_gated_cfg;
+use rustc_hir::def_id::LOCAL_CRATE;
 use rustc_interface::util::{self, collect_crate_types, get_codegen_backend};
 use rustc_interface::{interface, Queries};
 use rustc_lint::LintStore;
@@ -374,14 +375,14 @@ fn run_compiler(
             queries.global_ctxt()?.peek_mut().enter(|tcx| {
                 let result = tcx.analysis(());
                 if sess.opts.unstable_opts.save_analysis {
-                    let crate_name = queries.crate_name()?.peek().clone();
+                    let crate_name = tcx.crate_name(LOCAL_CRATE);
                     sess.time("save_analysis", || {
                         save::process_crate(
                             tcx,
-                            &crate_name,
+                            crate_name,
                             compiler.input(),
                             None,
-                            DumpHandler::new(compiler.output_dir().as_deref(), &crate_name),
+                            DumpHandler::new(compiler.output_dir().as_deref(), crate_name),
                         )
                     });
                 }
@@ -678,7 +679,7 @@ fn print_crate_info(
                 let crate_types = collect_crate_types(sess, attrs);
                 for &style in &crate_types {
                     let fname =
-                        rustc_session::output::filename_for_input(sess, style, &id, &t_outputs);
+                        rustc_session::output::filename_for_input(sess, style, id, &t_outputs);
                     println!("{}", fname.file_name().unwrap().to_string_lossy());
                 }
             }
diff --git a/compiler/rustc_expand/src/base.rs b/compiler/rustc_expand/src/base.rs
index 13e2d1ebbe7..9d6a4f9a1fd 100644
--- a/compiler/rustc_expand/src/base.rs
+++ b/compiler/rustc_expand/src/base.rs
@@ -960,7 +960,7 @@ pub trait LintStoreExpand {
         node_id: NodeId,
         attrs: &[Attribute],
         items: &[P<Item>],
-        name: &str,
+        name: Symbol,
     );
 }
 
diff --git a/compiler/rustc_expand/src/expand.rs b/compiler/rustc_expand/src/expand.rs
index e799fa404f6..1014ec2209c 100644
--- a/compiler/rustc_expand/src/expand.rs
+++ b/compiler/rustc_expand/src/expand.rs
@@ -1122,7 +1122,7 @@ impl InvocationCollectorNode for P<ast::Item> {
                         ecx.current_expansion.lint_node_id,
                         &attrs,
                         &items,
-                        ident.name.as_str(),
+                        ident.name,
                     );
                 }
 
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index 636e6e1b48d..8bc022e1e17 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -827,7 +827,7 @@ impl<'tcx> AttributeMap<'tcx> {
 pub struct OwnerNodes<'tcx> {
     /// Pre-computed hash of the full HIR.
     pub hash_including_bodies: Fingerprint,
-    /// Pre-computed hash of the item signature, sithout recursing into the body.
+    /// Pre-computed hash of the item signature, without recursing into the body.
     pub hash_without_bodies: Fingerprint,
     /// Full HIR for the current owner.
     // The zeroth node's parent should never be accessed: the owner's parent is computed by the
diff --git a/compiler/rustc_hir/src/tests.rs b/compiler/rustc_hir/src/tests.rs
index 4636d515249..d4791150947 100644
--- a/compiler/rustc_hir/src/tests.rs
+++ b/compiler/rustc_hir/src/tests.rs
@@ -1,5 +1,7 @@
 use crate::definitions::{DefKey, DefPathData, DisambiguatedDefPathData};
 use rustc_span::def_id::{DefPathHash, StableCrateId};
+use rustc_span::edition::Edition;
+use rustc_span::{create_session_if_not_set_then, Symbol};
 
 #[test]
 fn def_path_hash_depends_on_crate_id() {
@@ -11,26 +13,28 @@ fn def_path_hash_depends_on_crate_id() {
     // the crate by changing the crate disambiguator (e.g. via bumping the
     // crate's version number).
 
-    let id0 = StableCrateId::new("foo", false, vec!["1".to_string()]);
-    let id1 = StableCrateId::new("foo", false, vec!["2".to_string()]);
+    create_session_if_not_set_then(Edition::Edition2024, |_| {
+        let id0 = StableCrateId::new(Symbol::intern("foo"), false, vec!["1".to_string()]);
+        let id1 = StableCrateId::new(Symbol::intern("foo"), false, vec!["2".to_string()]);
 
-    let h0 = mk_test_hash(id0);
-    let h1 = mk_test_hash(id1);
+        let h0 = mk_test_hash(id0);
+        let h1 = mk_test_hash(id1);
 
-    assert_ne!(h0.stable_crate_id(), h1.stable_crate_id());
-    assert_ne!(h0.local_hash(), h1.local_hash());
+        assert_ne!(h0.stable_crate_id(), h1.stable_crate_id());
+        assert_ne!(h0.local_hash(), h1.local_hash());
 
-    fn mk_test_hash(stable_crate_id: StableCrateId) -> DefPathHash {
-        let parent_hash = DefPathHash::new(stable_crate_id, 0);
+        fn mk_test_hash(stable_crate_id: StableCrateId) -> DefPathHash {
+            let parent_hash = DefPathHash::new(stable_crate_id, 0);
 
-        let key = DefKey {
-            parent: None,
-            disambiguated_data: DisambiguatedDefPathData {
-                data: DefPathData::CrateRoot,
-                disambiguator: 0,
-            },
-        };
+            let key = DefKey {
+                parent: None,
+                disambiguated_data: DisambiguatedDefPathData {
+                    data: DefPathData::CrateRoot,
+                    disambiguator: 0,
+                },
+            };
 
-        key.compute_stable_hash(parent_hash)
-    }
+            key.compute_stable_hash(parent_hash)
+        }
+    })
 }
diff --git a/compiler/rustc_hir_analysis/src/collect/generics_of.rs b/compiler/rustc_hir_analysis/src/collect/generics_of.rs
index 639f81f20bf..0a7e25300cb 100644
--- a/compiler/rustc_hir_analysis/src/collect/generics_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/generics_of.rs
@@ -4,7 +4,6 @@ use hir::{
     GenericParamKind, HirId, Node,
 };
 use rustc_hir as hir;
-use rustc_hir::def::DefKind;
 use rustc_hir::def_id::DefId;
 use rustc_middle::ty::{self, TyCtxt};
 use rustc_session::lint;
@@ -143,20 +142,7 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
             Some(tcx.typeck_root_def_id(def_id))
         }
         Node::Item(item) => match item.kind {
-            ItemKind::OpaqueTy(hir::OpaqueTy {
-                origin:
-                    hir::OpaqueTyOrigin::FnReturn(fn_def_id) | hir::OpaqueTyOrigin::AsyncFn(fn_def_id),
-                in_trait,
-                ..
-            }) => {
-                if in_trait {
-                    assert!(matches!(tcx.def_kind(fn_def_id), DefKind::AssocFn))
-                } else {
-                    assert!(matches!(tcx.def_kind(fn_def_id), DefKind::AssocFn | DefKind::Fn))
-                }
-                Some(fn_def_id.to_def_id())
-            }
-            ItemKind::OpaqueTy(hir::OpaqueTy { origin: hir::OpaqueTyOrigin::TyAlias, .. }) => {
+            ItemKind::OpaqueTy(hir::OpaqueTy { .. }) => {
                 let parent_id = tcx.hir().get_parent_item(hir_id);
                 assert_ne!(parent_id, hir::CRATE_OWNER_ID);
                 debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id);
diff --git a/compiler/rustc_hir_typeck/src/check.rs b/compiler/rustc_hir_typeck/src/check.rs
index 0c9a350c295..32f86b8042c 100644
--- a/compiler/rustc_hir_typeck/src/check.rs
+++ b/compiler/rustc_hir_typeck/src/check.rs
@@ -1,7 +1,7 @@
 use crate::coercion::CoerceMany;
 use crate::gather_locals::GatherLocalsVisitor;
 use crate::FnCtxt;
-use crate::{GeneratorTypes, UnsafetyState};
+use crate::GeneratorTypes;
 use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::intravisit::Visitor;
@@ -30,7 +30,6 @@ pub(super) fn check_fn<'a, 'tcx>(
     can_be_generator: Option<hir::Movability>,
 ) -> Option<GeneratorTypes<'tcx>> {
     let fn_id = fcx.tcx.hir().local_def_id_to_hir_id(fn_def_id);
-    fcx.ps.set(UnsafetyState::function(fn_sig.unsafety, fn_id));
 
     let tcx = fcx.tcx;
     let hir = tcx.hir();
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
index 8a875e05b19..60fec05d36d 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
@@ -1393,8 +1393,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         blk: &'tcx hir::Block<'tcx>,
         expected: Expectation<'tcx>,
     ) -> Ty<'tcx> {
-        let prev = self.ps.replace(self.ps.get().recurse(blk));
-
         // In some cases, blocks have just one exit, but other blocks
         // can be targeted by multiple breaks. This can happen both
         // with labeled blocks as well as when we desugar
@@ -1558,7 +1556,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         self.write_ty(blk.hir_id, ty);
 
-        self.ps.set(prev);
         ty
     }
 
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
index 1e9b5752130..30b59da7852 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
@@ -8,7 +8,7 @@ use rustc_errors::ErrorGuaranteed;
 pub use suggestions::*;
 
 use crate::coercion::DynamicCoerceMany;
-use crate::{Diverges, EnclosingBreakables, Inherited, UnsafetyState};
+use crate::{Diverges, EnclosingBreakables, Inherited};
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_hir_analysis::astconv::AstConv;
@@ -74,8 +74,6 @@ pub struct FnCtxt<'a, 'tcx> {
 
     pub(super) resume_yield_tys: Option<(Ty<'tcx>, Ty<'tcx>)>,
 
-    pub(super) ps: Cell<UnsafetyState>,
-
     /// Whether the last checked node generates a divergence (e.g.,
     /// `return` will set this to `Always`). In general, when entering
     /// an expression or other node in the tree, the initial value
@@ -129,7 +127,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             ret_coercion: None,
             ret_coercion_span: Cell::new(None),
             resume_yield_tys: None,
-            ps: Cell::new(UnsafetyState::function(hir::Unsafety::Normal, hir::CRATE_HIR_ID)),
             diverges: Cell::new(Diverges::Maybe),
             enclosing_breakables: RefCell::new(EnclosingBreakables {
                 stack: Vec::new(),
diff --git a/compiler/rustc_hir_typeck/src/lib.rs b/compiler/rustc_hir_typeck/src/lib.rs
index 09bd123350d..5b2352cda34 100644
--- a/compiler/rustc_hir_typeck/src/lib.rs
+++ b/compiler/rustc_hir_typeck/src/lib.rs
@@ -89,38 +89,6 @@ pub struct LocalTy<'tcx> {
     revealed_ty: Ty<'tcx>,
 }
 
-#[derive(Copy, Clone)]
-pub struct UnsafetyState {
-    pub def: hir::HirId,
-    pub unsafety: hir::Unsafety,
-    from_fn: bool,
-}
-
-impl UnsafetyState {
-    pub fn function(unsafety: hir::Unsafety, def: hir::HirId) -> UnsafetyState {
-        UnsafetyState { def, unsafety, from_fn: true }
-    }
-
-    pub fn recurse(self, blk: &hir::Block<'_>) -> UnsafetyState {
-        use hir::BlockCheckMode;
-        match self.unsafety {
-            // If this unsafe, then if the outer function was already marked as
-            // unsafe we shouldn't attribute the unsafe'ness to the block. This
-            // way the block can be warned about instead of ignoring this
-            // extraneous block (functions are never warned about).
-            hir::Unsafety::Unsafe if self.from_fn => self,
-
-            unsafety => {
-                let (unsafety, def) = match blk.rules {
-                    BlockCheckMode::UnsafeBlock(..) => (hir::Unsafety::Unsafe, blk.hir_id),
-                    BlockCheckMode::DefaultBlock => (unsafety, self.def),
-                };
-                UnsafetyState { def, unsafety, from_fn: false }
-            }
-        }
-    }
-}
-
 /// If this `DefId` is a "primary tables entry", returns
 /// `Some((body_id, body_ty, fn_sig))`. Otherwise, returns `None`.
 ///
diff --git a/compiler/rustc_incremental/src/persist/fs.rs b/compiler/rustc_incremental/src/persist/fs.rs
index 58d6e6d7efd..97ebed05855 100644
--- a/compiler/rustc_incremental/src/persist/fs.rs
+++ b/compiler/rustc_incremental/src/persist/fs.rs
@@ -109,6 +109,7 @@ use rustc_data_structures::{base_n, flock};
 use rustc_errors::ErrorGuaranteed;
 use rustc_fs_util::{link_or_copy, LinkOrCopy};
 use rustc_session::{Session, StableCrateId};
+use rustc_span::Symbol;
 
 use std::fs as std_fs;
 use std::io::{self, ErrorKind};
@@ -202,7 +203,7 @@ pub fn in_incr_comp_dir(incr_comp_session_dir: &Path, file_name: &str) -> PathBu
 /// [`rustc_interface::queries::dep_graph`]: ../../rustc_interface/struct.Queries.html#structfield.dep_graph
 pub fn prepare_session_directory(
     sess: &Session,
-    crate_name: &str,
+    crate_name: Symbol,
     stable_crate_id: StableCrateId,
 ) -> Result<(), ErrorGuaranteed> {
     if sess.opts.incremental.is_none() {
@@ -657,7 +658,7 @@ fn string_to_timestamp(s: &str) -> Result<SystemTime, ()> {
     Ok(UNIX_EPOCH + duration)
 }
 
-fn crate_path(sess: &Session, crate_name: &str, stable_crate_id: StableCrateId) -> PathBuf {
+fn crate_path(sess: &Session, crate_name: Symbol, stable_crate_id: StableCrateId) -> PathBuf {
     let incr_dir = sess.opts.incremental.as_ref().unwrap().clone();
 
     let stable_crate_id = base_n::encode(stable_crate_id.to_u64() as u128, INT_ENCODE_BASE);
diff --git a/compiler/rustc_infer/src/infer/error_reporting/mod.rs b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
index 3256ca1fb20..987559d7e47 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/mod.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/mod.rs
@@ -56,22 +56,17 @@ use crate::infer::ExpectedFound;
 use crate::traits::error_reporting::report_object_safety_error;
 use crate::traits::{
     IfExpressionCause, MatchExpressionArmCause, ObligationCause, ObligationCauseCode,
-    StatementAsExpression,
 };
 
-use crate::errors::SuggAddLetForLetChains;
-use hir::intravisit::{walk_expr, walk_stmt};
 use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
 use rustc_errors::{pluralize, struct_span_err, Diagnostic, ErrorGuaranteed, IntoDiagnosticArg};
 use rustc_errors::{Applicability, DiagnosticBuilder, DiagnosticStyledString, MultiSpan};
 use rustc_hir as hir;
-use rustc_hir::def::{CtorKind, DefKind};
+use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LocalDefId};
-use rustc_hir::intravisit::Visitor;
 use rustc_hir::lang_items::LangItem;
 use rustc_hir::Node;
 use rustc_middle::dep_graph::DepContext;
-use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::relate::{self, RelateResult, TypeRelation};
 use rustc_middle::ty::{
     self, error::TypeError, List, Region, Ty, TyCtxt, TypeFoldable, TypeSuperVisitable,
@@ -80,9 +75,11 @@ use rustc_middle::ty::{
 use rustc_span::{sym, symbol::kw, BytePos, DesugaringKind, Pos, Span};
 use rustc_target::spec::abi;
 use std::ops::{ControlFlow, Deref};
+use std::path::PathBuf;
 use std::{cmp, fmt, iter};
 
 mod note;
+mod suggest;
 
 pub(crate) mod need_type_info;
 pub use need_type_info::TypeAnnotationNeeded;
@@ -806,87 +803,6 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         }
     }
 
-    fn suggest_remove_semi_or_return_binding(
-        &self,
-        err: &mut Diagnostic,
-        first_id: Option<hir::HirId>,
-        first_ty: Ty<'tcx>,
-        first_span: Span,
-        second_id: Option<hir::HirId>,
-        second_ty: Ty<'tcx>,
-        second_span: Span,
-    ) {
-        let remove_semicolon = [
-            (first_id, self.resolve_vars_if_possible(second_ty)),
-            (second_id, self.resolve_vars_if_possible(first_ty)),
-        ]
-        .into_iter()
-        .find_map(|(id, ty)| {
-            let hir::Node::Block(blk) = self.tcx.hir().get(id?) else { return None };
-            self.could_remove_semicolon(blk, ty)
-        });
-        match remove_semicolon {
-            Some((sp, StatementAsExpression::NeedsBoxing)) => {
-                err.multipart_suggestion(
-                    "consider removing this semicolon and boxing the expressions",
-                    vec![
-                        (first_span.shrink_to_lo(), "Box::new(".to_string()),
-                        (first_span.shrink_to_hi(), ")".to_string()),
-                        (second_span.shrink_to_lo(), "Box::new(".to_string()),
-                        (second_span.shrink_to_hi(), ")".to_string()),
-                        (sp, String::new()),
-                    ],
-                    Applicability::MachineApplicable,
-                );
-            }
-            Some((sp, StatementAsExpression::CorrectType)) => {
-                err.span_suggestion_short(
-                    sp,
-                    "consider removing this semicolon",
-                    "",
-                    Applicability::MachineApplicable,
-                );
-            }
-            None => {
-                for (id, ty) in [(first_id, second_ty), (second_id, first_ty)] {
-                    if let Some(id) = id
-                        && let hir::Node::Block(blk) = self.tcx.hir().get(id)
-                        && self.consider_returning_binding(blk, ty, err)
-                    {
-                        break;
-                    }
-                }
-            }
-        }
-    }
-
-    fn suggest_boxing_for_return_impl_trait(
-        &self,
-        err: &mut Diagnostic,
-        return_sp: Span,
-        arm_spans: impl Iterator<Item = Span>,
-    ) {
-        err.multipart_suggestion(
-            "you could change the return type to be a boxed trait object",
-            vec![
-                (return_sp.with_hi(return_sp.lo() + BytePos(4)), "Box<dyn".to_string()),
-                (return_sp.shrink_to_hi(), ">".to_string()),
-            ],
-            Applicability::MaybeIncorrect,
-        );
-        let sugg = arm_spans
-            .flat_map(|sp| {
-                [(sp.shrink_to_lo(), "Box::new(".to_string()), (sp.shrink_to_hi(), ")".to_string())]
-                    .into_iter()
-            })
-            .collect::<Vec<_>>();
-        err.multipart_suggestion(
-            "if you change the return type to expect trait objects, box the returned expressions",
-            sugg,
-            Applicability::MaybeIncorrect,
-        );
-    }
-
     /// Given that `other_ty` is the same as a type argument for `name` in `sub`, populate `value`
     /// highlighting `name` and every type argument that isn't at `pos` (which is `other_ty`), and
     /// populate `other_value` with `other_ty`.
@@ -1352,10 +1268,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                             .map(|(mod_str, _)| mod_str.len() + separator_len)
                             .sum();
 
-                    debug!(
-                        "cmp: separator_len={}, split_idx={}, min_len={}",
-                        separator_len, split_idx, min_len
-                    );
+                    debug!(?separator_len, ?split_idx, ?min_len, "cmp");
 
                     if split_idx >= min_len {
                         // paths are identical, highlight everything
@@ -1366,7 +1279,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     } else {
                         let (common, uniq1) = t1_str.split_at(split_idx);
                         let (_, uniq2) = t2_str.split_at(split_idx);
-                        debug!("cmp: common={}, uniq1={}, uniq2={}", common, uniq1, uniq2);
+                        debug!(?common, ?uniq1, ?uniq2, "cmp");
 
                         values.0.push_normal(common);
                         values.0.push_highlighted(uniq1);
@@ -1659,17 +1572,14 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     }
                     ValuePairs::Regions(_) => (false, Mismatch::Fixed("lifetime")),
                 };
-                let vals = match self.values_str(values) {
-                    Some((expected, found)) => Some((expected, found)),
-                    None => {
-                        // Derived error. Cancel the emitter.
-                        // NOTE(eddyb) this was `.cancel()`, but `diag`
-                        // is borrowed, so we can't fully defuse it.
-                        diag.downgrade_to_delayed_bug();
-                        return;
-                    }
+                let Some(vals) = self.values_str(values) else {
+                    // Derived error. Cancel the emitter.
+                    // NOTE(eddyb) this was `.cancel()`, but `diag`
+                    // is borrowed, so we can't fully defuse it.
+                    diag.downgrade_to_delayed_bug();
+                    return;
                 };
-                (vals, exp_found, is_simple_error, Some(values))
+                (Some(vals), exp_found, is_simple_error, Some(values))
             }
         };
 
@@ -1701,7 +1611,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             label_or_note(span, &terr.to_string());
         }
 
-        if let Some((expected, found)) = expected_found {
+        if let Some((expected, found, exp_p, found_p)) = expected_found {
             let (expected_label, found_label, exp_found) = match exp_found {
                 Mismatch::Variable(ef) => (
                     ef.expected.prefix_string(self.tcx),
@@ -1818,32 +1728,41 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                 }
                 TypeError::Sorts(values) => {
                     let extra = expected == found;
-                    let sort_string = |ty: Ty<'tcx>| match (extra, ty.kind()) {
-                        (true, ty::Opaque(def_id, _)) => {
-                            let sm = self.tcx.sess.source_map();
-                            let pos = sm.lookup_char_pos(self.tcx.def_span(*def_id).lo());
-                            format!(
-                                " (opaque type at <{}:{}:{}>)",
-                                sm.filename_for_diagnostics(&pos.file.name),
-                                pos.line,
-                                pos.col.to_usize() + 1,
-                            )
-                        }
-                        (true, ty::Projection(proj))
-                            if self.tcx.def_kind(proj.item_def_id)
-                                == DefKind::ImplTraitPlaceholder =>
-                        {
-                            let sm = self.tcx.sess.source_map();
-                            let pos = sm.lookup_char_pos(self.tcx.def_span(proj.item_def_id).lo());
-                            format!(
-                                " (trait associated opaque type at <{}:{}:{}>)",
-                                sm.filename_for_diagnostics(&pos.file.name),
-                                pos.line,
-                                pos.col.to_usize() + 1,
-                            )
+                    let sort_string = |ty: Ty<'tcx>, path: Option<PathBuf>| {
+                        let mut s = match (extra, ty.kind()) {
+                            (true, ty::Opaque(def_id, _)) => {
+                                let sm = self.tcx.sess.source_map();
+                                let pos = sm.lookup_char_pos(self.tcx.def_span(*def_id).lo());
+                                format!(
+                                    " (opaque type at <{}:{}:{}>)",
+                                    sm.filename_for_diagnostics(&pos.file.name),
+                                    pos.line,
+                                    pos.col.to_usize() + 1,
+                                )
+                            }
+                            (true, ty::Projection(proj))
+                                if self.tcx.def_kind(proj.item_def_id)
+                                    == DefKind::ImplTraitPlaceholder =>
+                            {
+                                let sm = self.tcx.sess.source_map();
+                                let pos = sm.lookup_char_pos(self.tcx.def_span(proj.item_def_id).lo());
+                                format!(
+                                    " (trait associated opaque type at <{}:{}:{}>)",
+                                    sm.filename_for_diagnostics(&pos.file.name),
+                                    pos.line,
+                                    pos.col.to_usize() + 1,
+                                )
+                            }
+                            (true, _) => format!(" ({})", ty.sort_string(self.tcx)),
+                            (false, _) => "".to_string(),
+                        };
+                        if let Some(path) = path {
+                            s.push_str(&format!(
+                                "\nthe full type name has been written to '{}'",
+                                path.display(),
+                            ));
                         }
-                        (true, _) => format!(" ({})", ty.sort_string(self.tcx)),
-                        (false, _) => "".to_string(),
+                        s
                     };
                     if !(values.expected.is_simple_text() && values.found.is_simple_text())
                         || (exp_found.map_or(false, |ef| {
@@ -1865,8 +1784,8 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                             expected,
                             &found_label,
                             found,
-                            &sort_string(values.expected),
-                            &sort_string(values.found),
+                            &sort_string(values.expected, exp_p),
+                            &sort_string(values.found, found_p),
                         );
                     }
                 }
@@ -1940,310 +1859,6 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         debug!(?diag);
     }
 
-    fn suggest_tuple_pattern(
-        &self,
-        cause: &ObligationCause<'tcx>,
-        exp_found: &ty::error::ExpectedFound<Ty<'tcx>>,
-        diag: &mut Diagnostic,
-    ) {
-        // Heavily inspired by `FnCtxt::suggest_compatible_variants`, with
-        // some modifications due to that being in typeck and this being in infer.
-        if let ObligationCauseCode::Pattern { .. } = cause.code() {
-            if let ty::Adt(expected_adt, substs) = exp_found.expected.kind() {
-                let compatible_variants: Vec<_> = expected_adt
-                    .variants()
-                    .iter()
-                    .filter(|variant| {
-                        variant.fields.len() == 1 && variant.ctor_kind() == Some(CtorKind::Fn)
-                    })
-                    .filter_map(|variant| {
-                        let sole_field = &variant.fields[0];
-                        let sole_field_ty = sole_field.ty(self.tcx, substs);
-                        if self.same_type_modulo_infer(sole_field_ty, exp_found.found) {
-                            let variant_path =
-                                with_no_trimmed_paths!(self.tcx.def_path_str(variant.def_id));
-                            // FIXME #56861: DRYer prelude filtering
-                            if let Some(path) = variant_path.strip_prefix("std::prelude::") {
-                                if let Some((_, path)) = path.split_once("::") {
-                                    return Some(path.to_string());
-                                }
-                            }
-                            Some(variant_path)
-                        } else {
-                            None
-                        }
-                    })
-                    .collect();
-                match &compatible_variants[..] {
-                    [] => {}
-                    [variant] => {
-                        diag.multipart_suggestion_verbose(
-                            &format!("try wrapping the pattern in `{}`", variant),
-                            vec![
-                                (cause.span.shrink_to_lo(), format!("{}(", variant)),
-                                (cause.span.shrink_to_hi(), ")".to_string()),
-                            ],
-                            Applicability::MaybeIncorrect,
-                        );
-                    }
-                    _ => {
-                        // More than one matching variant.
-                        diag.multipart_suggestions(
-                            &format!(
-                                "try wrapping the pattern in a variant of `{}`",
-                                self.tcx.def_path_str(expected_adt.did())
-                            ),
-                            compatible_variants.into_iter().map(|variant| {
-                                vec![
-                                    (cause.span.shrink_to_lo(), format!("{}(", variant)),
-                                    (cause.span.shrink_to_hi(), ")".to_string()),
-                                ]
-                            }),
-                            Applicability::MaybeIncorrect,
-                        );
-                    }
-                }
-            }
-        }
-    }
-
-    /// A possible error is to forget to add `.await` when using futures:
-    ///
-    /// ```compile_fail,E0308
-    /// async fn make_u32() -> u32 {
-    ///     22
-    /// }
-    ///
-    /// fn take_u32(x: u32) {}
-    ///
-    /// async fn foo() {
-    ///     let x = make_u32();
-    ///     take_u32(x);
-    /// }
-    /// ```
-    ///
-    /// This routine checks if the found type `T` implements `Future<Output=U>` where `U` is the
-    /// expected type. If this is the case, and we are inside of an async body, it suggests adding
-    /// `.await` to the tail of the expression.
-    fn suggest_await_on_expect_found(
-        &self,
-        cause: &ObligationCause<'tcx>,
-        exp_span: Span,
-        exp_found: &ty::error::ExpectedFound<Ty<'tcx>>,
-        diag: &mut Diagnostic,
-    ) {
-        debug!(
-            "suggest_await_on_expect_found: exp_span={:?}, expected_ty={:?}, found_ty={:?}",
-            exp_span, exp_found.expected, exp_found.found,
-        );
-
-        if let ObligationCauseCode::CompareImplItemObligation { .. } = cause.code() {
-            return;
-        }
-
-        match (
-            self.get_impl_future_output_ty(exp_found.expected),
-            self.get_impl_future_output_ty(exp_found.found),
-        ) {
-            (Some(exp), Some(found)) if self.same_type_modulo_infer(exp, found) => match cause
-                .code()
-            {
-                ObligationCauseCode::IfExpression(box IfExpressionCause { then_id, .. }) => {
-                    let then_span = self.find_block_span_from_hir_id(*then_id);
-                    diag.multipart_suggestion(
-                        "consider `await`ing on both `Future`s",
-                        vec![
-                            (then_span.shrink_to_hi(), ".await".to_string()),
-                            (exp_span.shrink_to_hi(), ".await".to_string()),
-                        ],
-                        Applicability::MaybeIncorrect,
-                    );
-                }
-                ObligationCauseCode::MatchExpressionArm(box MatchExpressionArmCause {
-                    prior_arms,
-                    ..
-                }) => {
-                    if let [.., arm_span] = &prior_arms[..] {
-                        diag.multipart_suggestion(
-                            "consider `await`ing on both `Future`s",
-                            vec![
-                                (arm_span.shrink_to_hi(), ".await".to_string()),
-                                (exp_span.shrink_to_hi(), ".await".to_string()),
-                            ],
-                            Applicability::MaybeIncorrect,
-                        );
-                    } else {
-                        diag.help("consider `await`ing on both `Future`s");
-                    }
-                }
-                _ => {
-                    diag.help("consider `await`ing on both `Future`s");
-                }
-            },
-            (_, Some(ty)) if self.same_type_modulo_infer(exp_found.expected, ty) => {
-                diag.span_suggestion_verbose(
-                    exp_span.shrink_to_hi(),
-                    "consider `await`ing on the `Future`",
-                    ".await",
-                    Applicability::MaybeIncorrect,
-                );
-            }
-            (Some(ty), _) if self.same_type_modulo_infer(ty, exp_found.found) => match cause.code()
-            {
-                ObligationCauseCode::Pattern { span: Some(then_span), .. } => {
-                    diag.span_suggestion_verbose(
-                        then_span.shrink_to_hi(),
-                        "consider `await`ing on the `Future`",
-                        ".await",
-                        Applicability::MaybeIncorrect,
-                    );
-                }
-                ObligationCauseCode::IfExpression(box IfExpressionCause { then_id, .. }) => {
-                    let then_span = self.find_block_span_from_hir_id(*then_id);
-                    diag.span_suggestion_verbose(
-                        then_span.shrink_to_hi(),
-                        "consider `await`ing on the `Future`",
-                        ".await",
-                        Applicability::MaybeIncorrect,
-                    );
-                }
-                ObligationCauseCode::MatchExpressionArm(box MatchExpressionArmCause {
-                    ref prior_arms,
-                    ..
-                }) => {
-                    diag.multipart_suggestion_verbose(
-                        "consider `await`ing on the `Future`",
-                        prior_arms
-                            .iter()
-                            .map(|arm| (arm.shrink_to_hi(), ".await".to_string()))
-                            .collect(),
-                        Applicability::MaybeIncorrect,
-                    );
-                }
-                _ => {}
-            },
-            _ => {}
-        }
-    }
-
-    fn suggest_accessing_field_where_appropriate(
-        &self,
-        cause: &ObligationCause<'tcx>,
-        exp_found: &ty::error::ExpectedFound<Ty<'tcx>>,
-        diag: &mut Diagnostic,
-    ) {
-        debug!(
-            "suggest_accessing_field_where_appropriate(cause={:?}, exp_found={:?})",
-            cause, exp_found
-        );
-        if let ty::Adt(expected_def, expected_substs) = exp_found.expected.kind() {
-            if expected_def.is_enum() {
-                return;
-            }
-
-            if let Some((name, ty)) = expected_def
-                .non_enum_variant()
-                .fields
-                .iter()
-                .filter(|field| field.vis.is_accessible_from(field.did, self.tcx))
-                .map(|field| (field.name, field.ty(self.tcx, expected_substs)))
-                .find(|(_, ty)| self.same_type_modulo_infer(*ty, exp_found.found))
-            {
-                if let ObligationCauseCode::Pattern { span: Some(span), .. } = *cause.code() {
-                    if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) {
-                        let suggestion = if expected_def.is_struct() {
-                            format!("{}.{}", snippet, name)
-                        } else if expected_def.is_union() {
-                            format!("unsafe {{ {}.{} }}", snippet, name)
-                        } else {
-                            return;
-                        };
-                        diag.span_suggestion(
-                            span,
-                            &format!(
-                                "you might have meant to use field `{}` whose type is `{}`",
-                                name, ty
-                            ),
-                            suggestion,
-                            Applicability::MaybeIncorrect,
-                        );
-                    }
-                }
-            }
-        }
-    }
-
-    /// When encountering a case where `.as_ref()` on a `Result` or `Option` would be appropriate,
-    /// suggests it.
-    fn suggest_as_ref_where_appropriate(
-        &self,
-        span: Span,
-        exp_found: &ty::error::ExpectedFound<Ty<'tcx>>,
-        diag: &mut Diagnostic,
-    ) {
-        if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span)
-            && let Some(msg) = self.should_suggest_as_ref(exp_found.expected, exp_found.found)
-        {
-            diag.span_suggestion(
-                span,
-                msg,
-                // HACK: fix issue# 100605, suggesting convert from &Option<T> to Option<&T>, remove the extra `&`
-                format!("{}.as_ref()", snippet.trim_start_matches('&')),
-                Applicability::MachineApplicable,
-            );
-        }
-    }
-
-    pub fn should_suggest_as_ref(&self, expected: Ty<'tcx>, found: Ty<'tcx>) -> Option<&str> {
-        if let (ty::Adt(exp_def, exp_substs), ty::Ref(_, found_ty, _)) =
-            (expected.kind(), found.kind())
-        {
-            if let ty::Adt(found_def, found_substs) = *found_ty.kind() {
-                if exp_def == &found_def {
-                    let have_as_ref = &[
-                        (
-                            sym::Option,
-                            "you can convert from `&Option<T>` to `Option<&T>` using \
-                        `.as_ref()`",
-                        ),
-                        (
-                            sym::Result,
-                            "you can convert from `&Result<T, E>` to \
-                        `Result<&T, &E>` using `.as_ref()`",
-                        ),
-                    ];
-                    if let Some(msg) = have_as_ref.iter().find_map(|(name, msg)| {
-                        self.tcx.is_diagnostic_item(*name, exp_def.did()).then_some(msg)
-                    }) {
-                        let mut show_suggestion = true;
-                        for (exp_ty, found_ty) in
-                            iter::zip(exp_substs.types(), found_substs.types())
-                        {
-                            match *exp_ty.kind() {
-                                ty::Ref(_, exp_ty, _) => {
-                                    match (exp_ty.kind(), found_ty.kind()) {
-                                        (_, ty::Param(_))
-                                        | (_, ty::Infer(_))
-                                        | (ty::Param(_), _)
-                                        | (ty::Infer(_), _) => {}
-                                        _ if self.same_type_modulo_infer(exp_ty, found_ty) => {}
-                                        _ => show_suggestion = false,
-                                    };
-                                }
-                                ty::Param(_) | ty::Infer(_) => {}
-                                _ => show_suggestion = false,
-                            }
-                        }
-                        if show_suggestion {
-                            return Some(*msg);
-                        }
-                    }
-                }
-            }
-        }
-        None
-    }
-
     pub fn report_and_explain_type_error(
         &self,
         trace: TypeTrace<'tcx>,
@@ -2339,7 +1954,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                 let code = trace.cause.code();
                 if let &MatchExpressionArm(box MatchExpressionArmCause { source, .. }) = code
                     && let hir::MatchSource::TryDesugar = source
-                    && let Some((expected_ty, found_ty)) = self.values_str(trace.values)
+                    && let Some((expected_ty, found_ty, _, _)) = self.values_str(trace.values)
                 {
                     err.note(&format!(
                         "`?` operator cannot convert from `{}` to `{}`",
@@ -2357,67 +1972,6 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         diag
     }
 
-    /// Try to find code with pattern `if Some(..) = expr`
-    /// use a `visitor` to mark the `if` which its span contains given error span,
-    /// and then try to find a assignment in the `cond` part, which span is equal with error span
-    fn suggest_let_for_letchains(
-        &self,
-        err: &mut Diagnostic,
-        cause: &ObligationCause<'_>,
-        span: Span,
-    ) {
-        let hir = self.tcx.hir();
-        let fn_hir_id = hir.get_parent_node(cause.body_id);
-        if let Some(node) = self.tcx.hir().find(fn_hir_id) &&
-            let hir::Node::Item(hir::Item {
-                    kind: hir::ItemKind::Fn(_sig, _, body_id), ..
-                }) = node {
-        let body = hir.body(*body_id);
-
-        /// Find the if expression with given span
-        struct IfVisitor {
-            pub result: bool,
-            pub found_if: bool,
-            pub err_span: Span,
-        }
-
-        impl<'v> Visitor<'v> for IfVisitor {
-            fn visit_expr(&mut self, ex: &'v hir::Expr<'v>) {
-                if self.result { return; }
-                match ex.kind {
-                    hir::ExprKind::If(cond, _, _) => {
-                        self.found_if = true;
-                        walk_expr(self, cond);
-                        self.found_if = false;
-                    }
-                    _ => walk_expr(self, ex),
-                }
-            }
-
-            fn visit_stmt(&mut self, ex: &'v hir::Stmt<'v>) {
-                if let hir::StmtKind::Local(hir::Local {
-                        span, pat: hir::Pat{..}, ty: None, init: Some(_), ..
-                    }) = &ex.kind
-                    && self.found_if
-                    && span.eq(&self.err_span) {
-                        self.result = true;
-                }
-                walk_stmt(self, ex);
-            }
-
-            fn visit_body(&mut self, body: &'v hir::Body<'v>) {
-                hir::intravisit::walk_body(self, body);
-            }
-        }
-
-        let mut visitor = IfVisitor { err_span: span, found_if: false, result: false };
-        visitor.visit_body(&body);
-        if visitor.result {
-                err.subdiagnostic(SuggAddLetForLetChains{span: span.shrink_to_lo()});
-            }
-        }
-    }
-
     fn emit_tuple_wrap_err(
         &self,
         err: &mut Diagnostic,
@@ -2455,7 +2009,8 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
     fn values_str(
         &self,
         values: ValuePairs<'tcx>,
-    ) -> Option<(DiagnosticStyledString, DiagnosticStyledString)> {
+    ) -> Option<(DiagnosticStyledString, DiagnosticStyledString, Option<PathBuf>, Option<PathBuf>)>
+    {
         match values {
             infer::Regions(exp_found) => self.expected_found_str(exp_found),
             infer::Terms(exp_found) => self.expected_found_str_term(exp_found),
@@ -2465,7 +2020,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     found: exp_found.found.print_only_trait_path(),
                 };
                 match self.expected_found_str(pretty_exp_found) {
-                    Some((expected, found)) if expected == found => {
+                    Some((expected, found, _, _)) if expected == found => {
                         self.expected_found_str(exp_found)
                     }
                     ret => ret,
@@ -2477,7 +2032,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     found: exp_found.found.print_only_trait_path(),
                 };
                 match self.expected_found_str(pretty_exp_found) {
-                    Some((expected, found)) if expected == found => {
+                    Some((expected, found, _, _)) if expected == found => {
                         self.expected_found_str(exp_found)
                     }
                     ret => ret,
@@ -2489,17 +2044,41 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
     fn expected_found_str_term(
         &self,
         exp_found: ty::error::ExpectedFound<ty::Term<'tcx>>,
-    ) -> Option<(DiagnosticStyledString, DiagnosticStyledString)> {
+    ) -> Option<(DiagnosticStyledString, DiagnosticStyledString, Option<PathBuf>, Option<PathBuf>)>
+    {
         let exp_found = self.resolve_vars_if_possible(exp_found);
         if exp_found.references_error() {
             return None;
         }
 
         Some(match (exp_found.expected.unpack(), exp_found.found.unpack()) {
-            (ty::TermKind::Ty(expected), ty::TermKind::Ty(found)) => self.cmp(expected, found),
+            (ty::TermKind::Ty(expected), ty::TermKind::Ty(found)) => {
+                let (mut exp, mut fnd) = self.cmp(expected, found);
+                // Use the terminal width as the basis to determine when to compress the printed
+                // out type, but give ourselves some leeway to avoid ending up creating a file for
+                // a type that is somewhat shorter than the path we'd write to.
+                let len = self.tcx.sess().diagnostic_width() + 40;
+                let exp_s = exp.content();
+                let fnd_s = fnd.content();
+                let mut exp_p = None;
+                let mut fnd_p = None;
+                if exp_s.len() > len {
+                    let (exp_s, exp_path) = self.tcx.short_ty_string(expected);
+                    exp = DiagnosticStyledString::highlighted(exp_s);
+                    exp_p = exp_path;
+                }
+                if fnd_s.len() > len {
+                    let (fnd_s, fnd_path) = self.tcx.short_ty_string(found);
+                    fnd = DiagnosticStyledString::highlighted(fnd_s);
+                    fnd_p = fnd_path;
+                }
+                (exp, fnd, exp_p, fnd_p)
+            }
             _ => (
                 DiagnosticStyledString::highlighted(exp_found.expected.to_string()),
                 DiagnosticStyledString::highlighted(exp_found.found.to_string()),
+                None,
+                None,
             ),
         })
     }
@@ -2508,7 +2087,8 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
     fn expected_found_str<T: fmt::Display + TypeFoldable<'tcx>>(
         &self,
         exp_found: ty::error::ExpectedFound<T>,
-    ) -> Option<(DiagnosticStyledString, DiagnosticStyledString)> {
+    ) -> Option<(DiagnosticStyledString, DiagnosticStyledString, Option<PathBuf>, Option<PathBuf>)>
+    {
         let exp_found = self.resolve_vars_if_possible(exp_found);
         if exp_found.references_error() {
             return None;
@@ -2517,6 +2097,8 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         Some((
             DiagnosticStyledString::highlighted(exp_found.expected.to_string()),
             DiagnosticStyledString::highlighted(exp_found.found.to_string()),
+            None,
+            None,
         ))
     }
 
@@ -2850,36 +2432,29 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         debug!("report_sub_sup_conflict: sup_region={:?}", sup_region);
         debug!("report_sub_sup_conflict: sup_origin={:?}", sup_origin);
 
-        if let (&infer::Subtype(ref sup_trace), &infer::Subtype(ref sub_trace)) =
-            (&sup_origin, &sub_origin)
+        if let infer::Subtype(ref sup_trace) = sup_origin
+            && let infer::Subtype(ref sub_trace) = sub_origin
+            && let Some((sup_expected, sup_found, _, _)) = self.values_str(sup_trace.values)
+            && let Some((sub_expected, sub_found, _, _)) = self.values_str(sub_trace.values)
+            && sub_expected == sup_expected
+            && sub_found == sup_found
         {
-            debug!("report_sub_sup_conflict: sup_trace={:?}", sup_trace);
-            debug!("report_sub_sup_conflict: sub_trace={:?}", sub_trace);
-            debug!("report_sub_sup_conflict: sup_trace.values={:?}", sup_trace.values);
-            debug!("report_sub_sup_conflict: sub_trace.values={:?}", sub_trace.values);
-
-            if let (Some((sup_expected, sup_found)), Some((sub_expected, sub_found))) =
-                (self.values_str(sup_trace.values), self.values_str(sub_trace.values))
-            {
-                if sub_expected == sup_expected && sub_found == sup_found {
-                    note_and_explain_region(
-                        self.tcx,
-                        &mut err,
-                        "...but the lifetime must also be valid for ",
-                        sub_region,
-                        "...",
-                        None,
-                    );
-                    err.span_note(
-                        sup_trace.cause.span,
-                        &format!("...so that the {}", sup_trace.cause.as_requirement_str()),
-                    );
+            note_and_explain_region(
+                self.tcx,
+                &mut err,
+                "...but the lifetime must also be valid for ",
+                sub_region,
+                "...",
+                None,
+            );
+            err.span_note(
+                sup_trace.cause.span,
+                &format!("...so that the {}", sup_trace.cause.as_requirement_str()),
+            );
 
-                    err.note_expected_found(&"", sup_expected, &"", sup_found);
-                    err.emit();
-                    return;
-                }
-            }
+            err.note_expected_found(&"", sup_expected, &"", sup_found);
+            err.emit();
+            return;
         }
 
         self.note_region_origin(&mut err, &sup_origin);
@@ -3228,211 +2803,3 @@ impl<'tcx> InferCtxt<'tcx> {
         }
     }
 }
-
-impl<'tcx> TypeErrCtxt<'_, 'tcx> {
-    /// Be helpful when the user wrote `{... expr; }` and taking the `;` off
-    /// is enough to fix the error.
-    pub fn could_remove_semicolon(
-        &self,
-        blk: &'tcx hir::Block<'tcx>,
-        expected_ty: Ty<'tcx>,
-    ) -> Option<(Span, StatementAsExpression)> {
-        let blk = blk.innermost_block();
-        // Do not suggest if we have a tail expr.
-        if blk.expr.is_some() {
-            return None;
-        }
-        let last_stmt = blk.stmts.last()?;
-        let hir::StmtKind::Semi(ref last_expr) = last_stmt.kind else {
-            return None;
-        };
-        let last_expr_ty = self.typeck_results.as_ref()?.expr_ty_opt(*last_expr)?;
-        let needs_box = match (last_expr_ty.kind(), expected_ty.kind()) {
-            _ if last_expr_ty.references_error() => return None,
-            _ if self.same_type_modulo_infer(last_expr_ty, expected_ty) => {
-                StatementAsExpression::CorrectType
-            }
-            (ty::Opaque(last_def_id, _), ty::Opaque(exp_def_id, _))
-                if last_def_id == exp_def_id =>
-            {
-                StatementAsExpression::CorrectType
-            }
-            (ty::Opaque(last_def_id, last_bounds), ty::Opaque(exp_def_id, exp_bounds)) => {
-                debug!(
-                    "both opaque, likely future {:?} {:?} {:?} {:?}",
-                    last_def_id, last_bounds, exp_def_id, exp_bounds
-                );
-
-                let last_local_id = last_def_id.as_local()?;
-                let exp_local_id = exp_def_id.as_local()?;
-
-                match (
-                    &self.tcx.hir().expect_item(last_local_id).kind,
-                    &self.tcx.hir().expect_item(exp_local_id).kind,
-                ) {
-                    (
-                        hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds: last_bounds, .. }),
-                        hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds: exp_bounds, .. }),
-                    ) if iter::zip(*last_bounds, *exp_bounds).all(|(left, right)| {
-                        match (left, right) {
-                            (
-                                hir::GenericBound::Trait(tl, ml),
-                                hir::GenericBound::Trait(tr, mr),
-                            ) if tl.trait_ref.trait_def_id() == tr.trait_ref.trait_def_id()
-                                && ml == mr =>
-                            {
-                                true
-                            }
-                            (
-                                hir::GenericBound::LangItemTrait(langl, _, _, argsl),
-                                hir::GenericBound::LangItemTrait(langr, _, _, argsr),
-                            ) if langl == langr => {
-                                // FIXME: consider the bounds!
-                                debug!("{:?} {:?}", argsl, argsr);
-                                true
-                            }
-                            _ => false,
-                        }
-                    }) =>
-                    {
-                        StatementAsExpression::NeedsBoxing
-                    }
-                    _ => StatementAsExpression::CorrectType,
-                }
-            }
-            _ => return None,
-        };
-        let span = if last_stmt.span.from_expansion() {
-            let mac_call = rustc_span::source_map::original_sp(last_stmt.span, blk.span);
-            self.tcx.sess.source_map().mac_call_stmt_semi_span(mac_call)?
-        } else {
-            last_stmt.span.with_lo(last_stmt.span.hi() - BytePos(1))
-        };
-        Some((span, needs_box))
-    }
-
-    /// Suggest returning a local binding with a compatible type if the block
-    /// has no return expression.
-    pub fn consider_returning_binding(
-        &self,
-        blk: &'tcx hir::Block<'tcx>,
-        expected_ty: Ty<'tcx>,
-        err: &mut Diagnostic,
-    ) -> bool {
-        let blk = blk.innermost_block();
-        // Do not suggest if we have a tail expr.
-        if blk.expr.is_some() {
-            return false;
-        }
-        let mut shadowed = FxIndexSet::default();
-        let mut candidate_idents = vec![];
-        let mut find_compatible_candidates = |pat: &hir::Pat<'_>| {
-            if let hir::PatKind::Binding(_, hir_id, ident, _) = &pat.kind
-                && let Some(pat_ty) = self
-                    .typeck_results
-                    .as_ref()
-                    .and_then(|typeck_results| typeck_results.node_type_opt(*hir_id))
-            {
-                let pat_ty = self.resolve_vars_if_possible(pat_ty);
-                if self.same_type_modulo_infer(pat_ty, expected_ty)
-                    && !(pat_ty, expected_ty).references_error()
-                    && shadowed.insert(ident.name)
-                {
-                    candidate_idents.push((*ident, pat_ty));
-                }
-            }
-            true
-        };
-
-        let hir = self.tcx.hir();
-        for stmt in blk.stmts.iter().rev() {
-            let hir::StmtKind::Local(local) = &stmt.kind else { continue; };
-            local.pat.walk(&mut find_compatible_candidates);
-        }
-        match hir.find(hir.get_parent_node(blk.hir_id)) {
-            Some(hir::Node::Expr(hir::Expr { hir_id, .. })) => {
-                match hir.find(hir.get_parent_node(*hir_id)) {
-                    Some(hir::Node::Arm(hir::Arm { pat, .. })) => {
-                        pat.walk(&mut find_compatible_candidates);
-                    }
-                    Some(
-                        hir::Node::Item(hir::Item { kind: hir::ItemKind::Fn(_, _, body), .. })
-                        | hir::Node::ImplItem(hir::ImplItem {
-                            kind: hir::ImplItemKind::Fn(_, body),
-                            ..
-                        })
-                        | hir::Node::TraitItem(hir::TraitItem {
-                            kind: hir::TraitItemKind::Fn(_, hir::TraitFn::Provided(body)),
-                            ..
-                        })
-                        | hir::Node::Expr(hir::Expr {
-                            kind: hir::ExprKind::Closure(hir::Closure { body, .. }),
-                            ..
-                        }),
-                    ) => {
-                        for param in hir.body(*body).params {
-                            param.pat.walk(&mut find_compatible_candidates);
-                        }
-                    }
-                    Some(hir::Node::Expr(hir::Expr {
-                        kind:
-                            hir::ExprKind::If(
-                                hir::Expr { kind: hir::ExprKind::Let(let_), .. },
-                                then_block,
-                                _,
-                            ),
-                        ..
-                    })) if then_block.hir_id == *hir_id => {
-                        let_.pat.walk(&mut find_compatible_candidates);
-                    }
-                    _ => {}
-                }
-            }
-            _ => {}
-        }
-
-        match &candidate_idents[..] {
-            [(ident, _ty)] => {
-                let sm = self.tcx.sess.source_map();
-                if let Some(stmt) = blk.stmts.last() {
-                    let stmt_span = sm.stmt_span(stmt.span, blk.span);
-                    let sugg = if sm.is_multiline(blk.span)
-                        && let Some(spacing) = sm.indentation_before(stmt_span)
-                    {
-                        format!("\n{spacing}{ident}")
-                    } else {
-                        format!(" {ident}")
-                    };
-                    err.span_suggestion_verbose(
-                        stmt_span.shrink_to_hi(),
-                        format!("consider returning the local binding `{ident}`"),
-                        sugg,
-                        Applicability::MaybeIncorrect,
-                    );
-                } else {
-                    let sugg = if sm.is_multiline(blk.span)
-                        && let Some(spacing) = sm.indentation_before(blk.span.shrink_to_lo())
-                    {
-                        format!("\n{spacing}    {ident}\n{spacing}")
-                    } else {
-                        format!(" {ident} ")
-                    };
-                    let left_span = sm.span_through_char(blk.span, '{').shrink_to_hi();
-                    err.span_suggestion_verbose(
-                        sm.span_extend_while(left_span, |c| c.is_whitespace()).unwrap_or(left_span),
-                        format!("consider returning the local binding `{ident}`"),
-                        sugg,
-                        Applicability::MaybeIncorrect,
-                    );
-                }
-                true
-            }
-            values if (1..3).contains(&values.len()) => {
-                let spans = values.iter().map(|(ident, _)| ident.span).collect::<Vec<_>>();
-                err.span_note(spans, "consider returning one of these bindings");
-                true
-            }
-            _ => false,
-        }
-    }
-}
diff --git a/compiler/rustc_infer/src/infer/error_reporting/note.rs b/compiler/rustc_infer/src/infer/error_reporting/note.rs
index 41b115f3377..d2dffa4a0b7 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/note.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/note.rs
@@ -16,7 +16,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             infer::Subtype(ref trace) => RegionOriginNote::WithRequirement {
                 span: trace.cause.span,
                 requirement: ObligationCauseAsDiagArg(trace.cause.clone()),
-                expected_found: self.values_str(trace.values),
+                expected_found: self.values_str(trace.values).map(|(e, f, _, _)| (e, f)),
             }
             .add_to_diagnostic(err),
             infer::Reborrow(span) => {
diff --git a/compiler/rustc_infer/src/infer/error_reporting/note_region.rs b/compiler/rustc_infer/src/infer/error_reporting/note_region.rs
new file mode 100644
index 00000000000..41b115f3377
--- /dev/null
+++ b/compiler/rustc_infer/src/infer/error_reporting/note_region.rs
@@ -0,0 +1,427 @@
+use crate::errors::RegionOriginNote;
+use crate::infer::error_reporting::{note_and_explain_region, TypeErrCtxt};
+use crate::infer::{self, SubregionOrigin};
+use rustc_errors::{
+    fluent, struct_span_err, AddToDiagnostic, Diagnostic, DiagnosticBuilder, ErrorGuaranteed,
+};
+use rustc_middle::traits::ObligationCauseCode;
+use rustc_middle::ty::error::TypeError;
+use rustc_middle::ty::{self, Region};
+
+use super::ObligationCauseAsDiagArg;
+
+impl<'tcx> TypeErrCtxt<'_, 'tcx> {
+    pub(super) fn note_region_origin(&self, err: &mut Diagnostic, origin: &SubregionOrigin<'tcx>) {
+        match *origin {
+            infer::Subtype(ref trace) => RegionOriginNote::WithRequirement {
+                span: trace.cause.span,
+                requirement: ObligationCauseAsDiagArg(trace.cause.clone()),
+                expected_found: self.values_str(trace.values),
+            }
+            .add_to_diagnostic(err),
+            infer::Reborrow(span) => {
+                RegionOriginNote::Plain { span, msg: fluent::infer_reborrow }.add_to_diagnostic(err)
+            }
+            infer::ReborrowUpvar(span, ref upvar_id) => {
+                let var_name = self.tcx.hir().name(upvar_id.var_path.hir_id);
+                RegionOriginNote::WithName {
+                    span,
+                    msg: fluent::infer_reborrow,
+                    name: &var_name.to_string(),
+                    continues: false,
+                }
+                .add_to_diagnostic(err);
+            }
+            infer::RelateObjectBound(span) => {
+                RegionOriginNote::Plain { span, msg: fluent::infer_relate_object_bound }
+                    .add_to_diagnostic(err);
+            }
+            infer::DataBorrowed(ty, span) => {
+                RegionOriginNote::WithName {
+                    span,
+                    msg: fluent::infer_data_borrowed,
+                    name: &self.ty_to_string(ty),
+                    continues: false,
+                }
+                .add_to_diagnostic(err);
+            }
+            infer::ReferenceOutlivesReferent(ty, span) => {
+                RegionOriginNote::WithName {
+                    span,
+                    msg: fluent::infer_reference_outlives_referent,
+                    name: &self.ty_to_string(ty),
+                    continues: false,
+                }
+                .add_to_diagnostic(err);
+            }
+            infer::RelateParamBound(span, ty, opt_span) => {
+                RegionOriginNote::WithName {
+                    span,
+                    msg: fluent::infer_relate_param_bound,
+                    name: &self.ty_to_string(ty),
+                    continues: opt_span.is_some(),
+                }
+                .add_to_diagnostic(err);
+                if let Some(span) = opt_span {
+                    RegionOriginNote::Plain { span, msg: fluent::infer_relate_param_bound_2 }
+                        .add_to_diagnostic(err);
+                }
+            }
+            infer::RelateRegionParamBound(span) => {
+                RegionOriginNote::Plain { span, msg: fluent::infer_relate_region_param_bound }
+                    .add_to_diagnostic(err);
+            }
+            infer::CompareImplItemObligation { span, .. } => {
+                RegionOriginNote::Plain { span, msg: fluent::infer_compare_impl_item_obligation }
+                    .add_to_diagnostic(err);
+            }
+            infer::CheckAssociatedTypeBounds { ref parent, .. } => {
+                self.note_region_origin(err, &parent);
+            }
+            infer::AscribeUserTypeProvePredicate(span) => {
+                RegionOriginNote::Plain {
+                    span,
+                    msg: fluent::infer_ascribe_user_type_prove_predicate,
+                }
+                .add_to_diagnostic(err);
+            }
+        }
+    }
+
+    pub(super) fn report_concrete_failure(
+        &self,
+        origin: SubregionOrigin<'tcx>,
+        sub: Region<'tcx>,
+        sup: Region<'tcx>,
+    ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
+        match origin {
+            infer::Subtype(box trace) => {
+                let terr = TypeError::RegionsDoesNotOutlive(sup, sub);
+                let mut err = self.report_and_explain_type_error(trace, terr);
+                match (*sub, *sup) {
+                    (ty::RePlaceholder(_), ty::RePlaceholder(_)) => {}
+                    (ty::RePlaceholder(_), _) => {
+                        note_and_explain_region(
+                            self.tcx,
+                            &mut err,
+                            "",
+                            sup,
+                            " doesn't meet the lifetime requirements",
+                            None,
+                        );
+                    }
+                    (_, ty::RePlaceholder(_)) => {
+                        note_and_explain_region(
+                            self.tcx,
+                            &mut err,
+                            "the required lifetime does not necessarily outlive ",
+                            sub,
+                            "",
+                            None,
+                        );
+                    }
+                    _ => {
+                        note_and_explain_region(self.tcx, &mut err, "", sup, "...", None);
+                        note_and_explain_region(
+                            self.tcx,
+                            &mut err,
+                            "...does not necessarily outlive ",
+                            sub,
+                            "",
+                            None,
+                        );
+                    }
+                }
+                err
+            }
+            infer::Reborrow(span) => {
+                let mut err = struct_span_err!(
+                    self.tcx.sess,
+                    span,
+                    E0312,
+                    "lifetime of reference outlives lifetime of borrowed content..."
+                );
+                note_and_explain_region(
+                    self.tcx,
+                    &mut err,
+                    "...the reference is valid for ",
+                    sub,
+                    "...",
+                    None,
+                );
+                note_and_explain_region(
+                    self.tcx,
+                    &mut err,
+                    "...but the borrowed content is only valid for ",
+                    sup,
+                    "",
+                    None,
+                );
+                err
+            }
+            infer::ReborrowUpvar(span, ref upvar_id) => {
+                let var_name = self.tcx.hir().name(upvar_id.var_path.hir_id);
+                let mut err = struct_span_err!(
+                    self.tcx.sess,
+                    span,
+                    E0313,
+                    "lifetime of borrowed pointer outlives lifetime of captured variable `{}`...",
+                    var_name
+                );
+                note_and_explain_region(
+                    self.tcx,
+                    &mut err,
+                    "...the borrowed pointer is valid for ",
+                    sub,
+                    "...",
+                    None,
+                );
+                note_and_explain_region(
+                    self.tcx,
+                    &mut err,
+                    &format!("...but `{}` is only valid for ", var_name),
+                    sup,
+                    "",
+                    None,
+                );
+                err
+            }
+            infer::RelateObjectBound(span) => {
+                let mut err = struct_span_err!(
+                    self.tcx.sess,
+                    span,
+                    E0476,
+                    "lifetime of the source pointer does not outlive lifetime bound of the \
+                     object type"
+                );
+                note_and_explain_region(
+                    self.tcx,
+                    &mut err,
+                    "object type is valid for ",
+                    sub,
+                    "",
+                    None,
+                );
+                note_and_explain_region(
+                    self.tcx,
+                    &mut err,
+                    "source pointer is only valid for ",
+                    sup,
+                    "",
+                    None,
+                );
+                err
+            }
+            infer::RelateParamBound(span, ty, opt_span) => {
+                let mut err = struct_span_err!(
+                    self.tcx.sess,
+                    span,
+                    E0477,
+                    "the type `{}` does not fulfill the required lifetime",
+                    self.ty_to_string(ty)
+                );
+                match *sub {
+                    ty::ReStatic => note_and_explain_region(
+                        self.tcx,
+                        &mut err,
+                        "type must satisfy ",
+                        sub,
+                        if opt_span.is_some() { " as required by this binding" } else { "" },
+                        opt_span,
+                    ),
+                    _ => note_and_explain_region(
+                        self.tcx,
+                        &mut err,
+                        "type must outlive ",
+                        sub,
+                        if opt_span.is_some() { " as required by this binding" } else { "" },
+                        opt_span,
+                    ),
+                }
+                err
+            }
+            infer::RelateRegionParamBound(span) => {
+                let mut err =
+                    struct_span_err!(self.tcx.sess, span, E0478, "lifetime bound not satisfied");
+                note_and_explain_region(
+                    self.tcx,
+                    &mut err,
+                    "lifetime parameter instantiated with ",
+                    sup,
+                    "",
+                    None,
+                );
+                note_and_explain_region(
+                    self.tcx,
+                    &mut err,
+                    "but lifetime parameter must outlive ",
+                    sub,
+                    "",
+                    None,
+                );
+                err
+            }
+            infer::DataBorrowed(ty, span) => {
+                let mut err = struct_span_err!(
+                    self.tcx.sess,
+                    span,
+                    E0490,
+                    "a value of type `{}` is borrowed for too long",
+                    self.ty_to_string(ty)
+                );
+                note_and_explain_region(
+                    self.tcx,
+                    &mut err,
+                    "the type is valid for ",
+                    sub,
+                    "",
+                    None,
+                );
+                note_and_explain_region(
+                    self.tcx,
+                    &mut err,
+                    "but the borrow lasts for ",
+                    sup,
+                    "",
+                    None,
+                );
+                err
+            }
+            infer::ReferenceOutlivesReferent(ty, span) => {
+                let mut err = struct_span_err!(
+                    self.tcx.sess,
+                    span,
+                    E0491,
+                    "in type `{}`, reference has a longer lifetime than the data it references",
+                    self.ty_to_string(ty)
+                );
+                note_and_explain_region(
+                    self.tcx,
+                    &mut err,
+                    "the pointer is valid for ",
+                    sub,
+                    "",
+                    None,
+                );
+                note_and_explain_region(
+                    self.tcx,
+                    &mut err,
+                    "but the referenced data is only valid for ",
+                    sup,
+                    "",
+                    None,
+                );
+                err
+            }
+            infer::CompareImplItemObligation { span, impl_item_def_id, trait_item_def_id } => self
+                .report_extra_impl_obligation(
+                    span,
+                    impl_item_def_id,
+                    trait_item_def_id,
+                    &format!("`{}: {}`", sup, sub),
+                ),
+            infer::CheckAssociatedTypeBounds { impl_item_def_id, trait_item_def_id, parent } => {
+                let mut err = self.report_concrete_failure(*parent, sub, sup);
+
+                let trait_item_span = self.tcx.def_span(trait_item_def_id);
+                let item_name = self.tcx.item_name(impl_item_def_id.to_def_id());
+                err.span_label(
+                    trait_item_span,
+                    format!("definition of `{}` from trait", item_name),
+                );
+
+                let trait_predicates = self.tcx.explicit_predicates_of(trait_item_def_id);
+                let impl_predicates = self.tcx.explicit_predicates_of(impl_item_def_id);
+
+                let impl_predicates: rustc_data_structures::fx::FxHashSet<_> =
+                    impl_predicates.predicates.into_iter().map(|(pred, _)| pred).collect();
+                let clauses: Vec<_> = trait_predicates
+                    .predicates
+                    .into_iter()
+                    .filter(|&(pred, _)| !impl_predicates.contains(pred))
+                    .map(|(pred, _)| format!("{}", pred))
+                    .collect();
+
+                if !clauses.is_empty() {
+                    let generics = self.tcx.hir().get_generics(impl_item_def_id).unwrap();
+                    let where_clause_span = generics.tail_span_for_predicate_suggestion();
+
+                    let suggestion = format!(
+                        "{} {}",
+                        generics.add_where_or_trailing_comma(),
+                        clauses.join(", "),
+                    );
+                    err.span_suggestion(
+                        where_clause_span,
+                        &format!(
+                            "try copying {} from the trait",
+                            if clauses.len() > 1 { "these clauses" } else { "this clause" }
+                        ),
+                        suggestion,
+                        rustc_errors::Applicability::MaybeIncorrect,
+                    );
+                }
+
+                err
+            }
+            infer::AscribeUserTypeProvePredicate(span) => {
+                let mut err =
+                    struct_span_err!(self.tcx.sess, span, E0478, "lifetime bound not satisfied");
+                note_and_explain_region(
+                    self.tcx,
+                    &mut err,
+                    "lifetime instantiated with ",
+                    sup,
+                    "",
+                    None,
+                );
+                note_and_explain_region(
+                    self.tcx,
+                    &mut err,
+                    "but lifetime must outlive ",
+                    sub,
+                    "",
+                    None,
+                );
+                err
+            }
+        }
+    }
+
+    pub(super) fn report_placeholder_failure(
+        &self,
+        placeholder_origin: SubregionOrigin<'tcx>,
+        sub: Region<'tcx>,
+        sup: Region<'tcx>,
+    ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
+        // I can't think how to do better than this right now. -nikomatsakis
+        debug!(?placeholder_origin, ?sub, ?sup, "report_placeholder_failure");
+        match placeholder_origin {
+            infer::Subtype(box ref trace)
+                if matches!(
+                    &trace.cause.code().peel_derives(),
+                    ObligationCauseCode::BindingObligation(..)
+                        | ObligationCauseCode::ExprBindingObligation(..)
+                ) =>
+            {
+                // Hack to get around the borrow checker because trace.cause has an `Rc`.
+                if let ObligationCauseCode::BindingObligation(_, span)
+                | ObligationCauseCode::ExprBindingObligation(_, span, ..) =
+                    &trace.cause.code().peel_derives()
+                {
+                    let span = *span;
+                    let mut err = self.report_concrete_failure(placeholder_origin, sub, sup);
+                    err.span_note(span, "the lifetime requirement is introduced here");
+                    err
+                } else {
+                    unreachable!()
+                }
+            }
+            infer::Subtype(box trace) => {
+                let terr = TypeError::RegionsPlaceholderMismatch;
+                return self.report_and_explain_type_error(trace, terr);
+            }
+            _ => return self.report_concrete_failure(placeholder_origin, sub, sup),
+        }
+    }
+}
diff --git a/compiler/rustc_infer/src/infer/error_reporting/suggest.rs b/compiler/rustc_infer/src/infer/error_reporting/suggest.rs
new file mode 100644
index 00000000000..73b5a2cc4ad
--- /dev/null
+++ b/compiler/rustc_infer/src/infer/error_reporting/suggest.rs
@@ -0,0 +1,672 @@
+use hir::def::CtorKind;
+use hir::intravisit::{walk_expr, walk_stmt, Visitor};
+use rustc_data_structures::fx::FxIndexSet;
+use rustc_errors::{Applicability, Diagnostic};
+use rustc_hir as hir;
+use rustc_middle::traits::{
+    IfExpressionCause, MatchExpressionArmCause, ObligationCause, ObligationCauseCode,
+    StatementAsExpression,
+};
+use rustc_middle::ty::print::with_no_trimmed_paths;
+use rustc_middle::ty::{self as ty, Ty, TypeVisitable};
+use rustc_span::{sym, BytePos, Span};
+
+use crate::errors::SuggAddLetForLetChains;
+
+use super::TypeErrCtxt;
+
+impl<'tcx> TypeErrCtxt<'_, 'tcx> {
+    pub(super) fn suggest_remove_semi_or_return_binding(
+        &self,
+        err: &mut Diagnostic,
+        first_id: Option<hir::HirId>,
+        first_ty: Ty<'tcx>,
+        first_span: Span,
+        second_id: Option<hir::HirId>,
+        second_ty: Ty<'tcx>,
+        second_span: Span,
+    ) {
+        let remove_semicolon = [
+            (first_id, self.resolve_vars_if_possible(second_ty)),
+            (second_id, self.resolve_vars_if_possible(first_ty)),
+        ]
+        .into_iter()
+        .find_map(|(id, ty)| {
+            let hir::Node::Block(blk) = self.tcx.hir().get(id?) else { return None };
+            self.could_remove_semicolon(blk, ty)
+        });
+        match remove_semicolon {
+            Some((sp, StatementAsExpression::NeedsBoxing)) => {
+                err.multipart_suggestion(
+                    "consider removing this semicolon and boxing the expressions",
+                    vec![
+                        (first_span.shrink_to_lo(), "Box::new(".to_string()),
+                        (first_span.shrink_to_hi(), ")".to_string()),
+                        (second_span.shrink_to_lo(), "Box::new(".to_string()),
+                        (second_span.shrink_to_hi(), ")".to_string()),
+                        (sp, String::new()),
+                    ],
+                    Applicability::MachineApplicable,
+                );
+            }
+            Some((sp, StatementAsExpression::CorrectType)) => {
+                err.span_suggestion_short(
+                    sp,
+                    "consider removing this semicolon",
+                    "",
+                    Applicability::MachineApplicable,
+                );
+            }
+            None => {
+                for (id, ty) in [(first_id, second_ty), (second_id, first_ty)] {
+                    if let Some(id) = id
+                        && let hir::Node::Block(blk) = self.tcx.hir().get(id)
+                        && self.consider_returning_binding(blk, ty, err)
+                    {
+                        break;
+                    }
+                }
+            }
+        }
+    }
+
+    pub(super) fn suggest_boxing_for_return_impl_trait(
+        &self,
+        err: &mut Diagnostic,
+        return_sp: Span,
+        arm_spans: impl Iterator<Item = Span>,
+    ) {
+        err.multipart_suggestion(
+            "you could change the return type to be a boxed trait object",
+            vec![
+                (return_sp.with_hi(return_sp.lo() + BytePos(4)), "Box<dyn".to_string()),
+                (return_sp.shrink_to_hi(), ">".to_string()),
+            ],
+            Applicability::MaybeIncorrect,
+        );
+        let sugg = arm_spans
+            .flat_map(|sp| {
+                [(sp.shrink_to_lo(), "Box::new(".to_string()), (sp.shrink_to_hi(), ")".to_string())]
+                    .into_iter()
+            })
+            .collect::<Vec<_>>();
+        err.multipart_suggestion(
+            "if you change the return type to expect trait objects, box the returned expressions",
+            sugg,
+            Applicability::MaybeIncorrect,
+        );
+    }
+
+    pub(super) fn suggest_tuple_pattern(
+        &self,
+        cause: &ObligationCause<'tcx>,
+        exp_found: &ty::error::ExpectedFound<Ty<'tcx>>,
+        diag: &mut Diagnostic,
+    ) {
+        // Heavily inspired by `FnCtxt::suggest_compatible_variants`, with
+        // some modifications due to that being in typeck and this being in infer.
+        if let ObligationCauseCode::Pattern { .. } = cause.code() {
+            if let ty::Adt(expected_adt, substs) = exp_found.expected.kind() {
+                let compatible_variants: Vec<_> = expected_adt
+                    .variants()
+                    .iter()
+                    .filter(|variant| {
+                        variant.fields.len() == 1 && variant.ctor_kind() == Some(CtorKind::Fn)
+                    })
+                    .filter_map(|variant| {
+                        let sole_field = &variant.fields[0];
+                        let sole_field_ty = sole_field.ty(self.tcx, substs);
+                        if self.same_type_modulo_infer(sole_field_ty, exp_found.found) {
+                            let variant_path =
+                                with_no_trimmed_paths!(self.tcx.def_path_str(variant.def_id));
+                            // FIXME #56861: DRYer prelude filtering
+                            if let Some(path) = variant_path.strip_prefix("std::prelude::") {
+                                if let Some((_, path)) = path.split_once("::") {
+                                    return Some(path.to_string());
+                                }
+                            }
+                            Some(variant_path)
+                        } else {
+                            None
+                        }
+                    })
+                    .collect();
+                match &compatible_variants[..] {
+                    [] => {}
+                    [variant] => {
+                        diag.multipart_suggestion_verbose(
+                            &format!("try wrapping the pattern in `{}`", variant),
+                            vec![
+                                (cause.span.shrink_to_lo(), format!("{}(", variant)),
+                                (cause.span.shrink_to_hi(), ")".to_string()),
+                            ],
+                            Applicability::MaybeIncorrect,
+                        );
+                    }
+                    _ => {
+                        // More than one matching variant.
+                        diag.multipart_suggestions(
+                            &format!(
+                                "try wrapping the pattern in a variant of `{}`",
+                                self.tcx.def_path_str(expected_adt.did())
+                            ),
+                            compatible_variants.into_iter().map(|variant| {
+                                vec![
+                                    (cause.span.shrink_to_lo(), format!("{}(", variant)),
+                                    (cause.span.shrink_to_hi(), ")".to_string()),
+                                ]
+                            }),
+                            Applicability::MaybeIncorrect,
+                        );
+                    }
+                }
+            }
+        }
+    }
+
+    /// A possible error is to forget to add `.await` when using futures:
+    ///
+    /// ```compile_fail,E0308
+    /// async fn make_u32() -> u32 {
+    ///     22
+    /// }
+    ///
+    /// fn take_u32(x: u32) {}
+    ///
+    /// async fn foo() {
+    ///     let x = make_u32();
+    ///     take_u32(x);
+    /// }
+    /// ```
+    ///
+    /// This routine checks if the found type `T` implements `Future<Output=U>` where `U` is the
+    /// expected type. If this is the case, and we are inside of an async body, it suggests adding
+    /// `.await` to the tail of the expression.
+    pub(super) fn suggest_await_on_expect_found(
+        &self,
+        cause: &ObligationCause<'tcx>,
+        exp_span: Span,
+        exp_found: &ty::error::ExpectedFound<Ty<'tcx>>,
+        diag: &mut Diagnostic,
+    ) {
+        debug!(
+            "suggest_await_on_expect_found: exp_span={:?}, expected_ty={:?}, found_ty={:?}",
+            exp_span, exp_found.expected, exp_found.found,
+        );
+
+        if let ObligationCauseCode::CompareImplItemObligation { .. } = cause.code() {
+            return;
+        }
+
+        match (
+            self.get_impl_future_output_ty(exp_found.expected),
+            self.get_impl_future_output_ty(exp_found.found),
+        ) {
+            (Some(exp), Some(found)) if self.same_type_modulo_infer(exp, found) => match cause
+                .code()
+            {
+                ObligationCauseCode::IfExpression(box IfExpressionCause { then_id, .. }) => {
+                    let then_span = self.find_block_span_from_hir_id(*then_id);
+                    diag.multipart_suggestion(
+                        "consider `await`ing on both `Future`s",
+                        vec![
+                            (then_span.shrink_to_hi(), ".await".to_string()),
+                            (exp_span.shrink_to_hi(), ".await".to_string()),
+                        ],
+                        Applicability::MaybeIncorrect,
+                    );
+                }
+                ObligationCauseCode::MatchExpressionArm(box MatchExpressionArmCause {
+                    prior_arms,
+                    ..
+                }) => {
+                    if let [.., arm_span] = &prior_arms[..] {
+                        diag.multipart_suggestion(
+                            "consider `await`ing on both `Future`s",
+                            vec![
+                                (arm_span.shrink_to_hi(), ".await".to_string()),
+                                (exp_span.shrink_to_hi(), ".await".to_string()),
+                            ],
+                            Applicability::MaybeIncorrect,
+                        );
+                    } else {
+                        diag.help("consider `await`ing on both `Future`s");
+                    }
+                }
+                _ => {
+                    diag.help("consider `await`ing on both `Future`s");
+                }
+            },
+            (_, Some(ty)) if self.same_type_modulo_infer(exp_found.expected, ty) => {
+                diag.span_suggestion_verbose(
+                    exp_span.shrink_to_hi(),
+                    "consider `await`ing on the `Future`",
+                    ".await",
+                    Applicability::MaybeIncorrect,
+                );
+            }
+            (Some(ty), _) if self.same_type_modulo_infer(ty, exp_found.found) => match cause.code()
+            {
+                ObligationCauseCode::Pattern { span: Some(then_span), .. } => {
+                    diag.span_suggestion_verbose(
+                        then_span.shrink_to_hi(),
+                        "consider `await`ing on the `Future`",
+                        ".await",
+                        Applicability::MaybeIncorrect,
+                    );
+                }
+                ObligationCauseCode::IfExpression(box IfExpressionCause { then_id, .. }) => {
+                    let then_span = self.find_block_span_from_hir_id(*then_id);
+                    diag.span_suggestion_verbose(
+                        then_span.shrink_to_hi(),
+                        "consider `await`ing on the `Future`",
+                        ".await",
+                        Applicability::MaybeIncorrect,
+                    );
+                }
+                ObligationCauseCode::MatchExpressionArm(box MatchExpressionArmCause {
+                    ref prior_arms,
+                    ..
+                }) => {
+                    diag.multipart_suggestion_verbose(
+                        "consider `await`ing on the `Future`",
+                        prior_arms
+                            .iter()
+                            .map(|arm| (arm.shrink_to_hi(), ".await".to_string()))
+                            .collect(),
+                        Applicability::MaybeIncorrect,
+                    );
+                }
+                _ => {}
+            },
+            _ => {}
+        }
+    }
+
+    pub(super) fn suggest_accessing_field_where_appropriate(
+        &self,
+        cause: &ObligationCause<'tcx>,
+        exp_found: &ty::error::ExpectedFound<Ty<'tcx>>,
+        diag: &mut Diagnostic,
+    ) {
+        debug!(
+            "suggest_accessing_field_where_appropriate(cause={:?}, exp_found={:?})",
+            cause, exp_found
+        );
+        if let ty::Adt(expected_def, expected_substs) = exp_found.expected.kind() {
+            if expected_def.is_enum() {
+                return;
+            }
+
+            if let Some((name, ty)) = expected_def
+                .non_enum_variant()
+                .fields
+                .iter()
+                .filter(|field| field.vis.is_accessible_from(field.did, self.tcx))
+                .map(|field| (field.name, field.ty(self.tcx, expected_substs)))
+                .find(|(_, ty)| self.same_type_modulo_infer(*ty, exp_found.found))
+            {
+                if let ObligationCauseCode::Pattern { span: Some(span), .. } = *cause.code() {
+                    if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) {
+                        let suggestion = if expected_def.is_struct() {
+                            format!("{}.{}", snippet, name)
+                        } else if expected_def.is_union() {
+                            format!("unsafe {{ {}.{} }}", snippet, name)
+                        } else {
+                            return;
+                        };
+                        diag.span_suggestion(
+                            span,
+                            &format!(
+                                "you might have meant to use field `{}` whose type is `{}`",
+                                name, ty
+                            ),
+                            suggestion,
+                            Applicability::MaybeIncorrect,
+                        );
+                    }
+                }
+            }
+        }
+    }
+
+    /// When encountering a case where `.as_ref()` on a `Result` or `Option` would be appropriate,
+    /// suggests it.
+    pub(super) fn suggest_as_ref_where_appropriate(
+        &self,
+        span: Span,
+        exp_found: &ty::error::ExpectedFound<Ty<'tcx>>,
+        diag: &mut Diagnostic,
+    ) {
+        if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span)
+            && let Some(msg) = self.should_suggest_as_ref(exp_found.expected, exp_found.found)
+        {
+            diag.span_suggestion(
+                span,
+                msg,
+                // HACK: fix issue# 100605, suggesting convert from &Option<T> to Option<&T>, remove the extra `&`
+                format!("{}.as_ref()", snippet.trim_start_matches('&')),
+                Applicability::MachineApplicable,
+            );
+        }
+    }
+
+    pub fn should_suggest_as_ref(&self, expected: Ty<'tcx>, found: Ty<'tcx>) -> Option<&str> {
+        if let (ty::Adt(exp_def, exp_substs), ty::Ref(_, found_ty, _)) =
+            (expected.kind(), found.kind())
+        {
+            if let ty::Adt(found_def, found_substs) = *found_ty.kind() {
+                if exp_def == &found_def {
+                    let have_as_ref = &[
+                        (
+                            sym::Option,
+                            "you can convert from `&Option<T>` to `Option<&T>` using \
+                        `.as_ref()`",
+                        ),
+                        (
+                            sym::Result,
+                            "you can convert from `&Result<T, E>` to \
+                        `Result<&T, &E>` using `.as_ref()`",
+                        ),
+                    ];
+                    if let Some(msg) = have_as_ref.iter().find_map(|(name, msg)| {
+                        self.tcx.is_diagnostic_item(*name, exp_def.did()).then_some(msg)
+                    }) {
+                        let mut show_suggestion = true;
+                        for (exp_ty, found_ty) in
+                            std::iter::zip(exp_substs.types(), found_substs.types())
+                        {
+                            match *exp_ty.kind() {
+                                ty::Ref(_, exp_ty, _) => {
+                                    match (exp_ty.kind(), found_ty.kind()) {
+                                        (_, ty::Param(_))
+                                        | (_, ty::Infer(_))
+                                        | (ty::Param(_), _)
+                                        | (ty::Infer(_), _) => {}
+                                        _ if self.same_type_modulo_infer(exp_ty, found_ty) => {}
+                                        _ => show_suggestion = false,
+                                    };
+                                }
+                                ty::Param(_) | ty::Infer(_) => {}
+                                _ => show_suggestion = false,
+                            }
+                        }
+                        if show_suggestion {
+                            return Some(*msg);
+                        }
+                    }
+                }
+            }
+        }
+        None
+    }
+
+    /// Try to find code with pattern `if Some(..) = expr`
+    /// use a `visitor` to mark the `if` which its span contains given error span,
+    /// and then try to find a assignment in the `cond` part, which span is equal with error span
+    pub(super) fn suggest_let_for_letchains(
+        &self,
+        err: &mut Diagnostic,
+        cause: &ObligationCause<'_>,
+        span: Span,
+    ) {
+        let hir = self.tcx.hir();
+        let fn_hir_id = hir.get_parent_node(cause.body_id);
+        if let Some(node) = self.tcx.hir().find(fn_hir_id) &&
+            let hir::Node::Item(hir::Item {
+                    kind: hir::ItemKind::Fn(_sig, _, body_id), ..
+                }) = node {
+        let body = hir.body(*body_id);
+
+        /// Find the if expression with given span
+        struct IfVisitor {
+            pub result: bool,
+            pub found_if: bool,
+            pub err_span: Span,
+        }
+
+        impl<'v> Visitor<'v> for IfVisitor {
+            fn visit_expr(&mut self, ex: &'v hir::Expr<'v>) {
+                if self.result { return; }
+                match ex.kind {
+                    hir::ExprKind::If(cond, _, _) => {
+                        self.found_if = true;
+                        walk_expr(self, cond);
+                        self.found_if = false;
+                    }
+                    _ => walk_expr(self, ex),
+                }
+            }
+
+            fn visit_stmt(&mut self, ex: &'v hir::Stmt<'v>) {
+                if let hir::StmtKind::Local(hir::Local {
+                        span, pat: hir::Pat{..}, ty: None, init: Some(_), ..
+                    }) = &ex.kind
+                    && self.found_if
+                    && span.eq(&self.err_span) {
+                        self.result = true;
+                }
+                walk_stmt(self, ex);
+            }
+
+            fn visit_body(&mut self, body: &'v hir::Body<'v>) {
+                hir::intravisit::walk_body(self, body);
+            }
+        }
+
+        let mut visitor = IfVisitor { err_span: span, found_if: false, result: false };
+        visitor.visit_body(&body);
+        if visitor.result {
+                err.subdiagnostic(SuggAddLetForLetChains{span: span.shrink_to_lo()});
+            }
+        }
+    }
+}
+
+impl<'tcx> TypeErrCtxt<'_, 'tcx> {
+    /// Be helpful when the user wrote `{... expr; }` and taking the `;` off
+    /// is enough to fix the error.
+    pub fn could_remove_semicolon(
+        &self,
+        blk: &'tcx hir::Block<'tcx>,
+        expected_ty: Ty<'tcx>,
+    ) -> Option<(Span, StatementAsExpression)> {
+        let blk = blk.innermost_block();
+        // Do not suggest if we have a tail expr.
+        if blk.expr.is_some() {
+            return None;
+        }
+        let last_stmt = blk.stmts.last()?;
+        let hir::StmtKind::Semi(ref last_expr) = last_stmt.kind else {
+            return None;
+        };
+        let last_expr_ty = self.typeck_results.as_ref()?.expr_ty_opt(*last_expr)?;
+        let needs_box = match (last_expr_ty.kind(), expected_ty.kind()) {
+            _ if last_expr_ty.references_error() => return None,
+            _ if self.same_type_modulo_infer(last_expr_ty, expected_ty) => {
+                StatementAsExpression::CorrectType
+            }
+            (ty::Opaque(last_def_id, _), ty::Opaque(exp_def_id, _))
+                if last_def_id == exp_def_id =>
+            {
+                StatementAsExpression::CorrectType
+            }
+            (ty::Opaque(last_def_id, last_bounds), ty::Opaque(exp_def_id, exp_bounds)) => {
+                debug!(
+                    "both opaque, likely future {:?} {:?} {:?} {:?}",
+                    last_def_id, last_bounds, exp_def_id, exp_bounds
+                );
+
+                let last_local_id = last_def_id.as_local()?;
+                let exp_local_id = exp_def_id.as_local()?;
+
+                match (
+                    &self.tcx.hir().expect_item(last_local_id).kind,
+                    &self.tcx.hir().expect_item(exp_local_id).kind,
+                ) {
+                    (
+                        hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds: last_bounds, .. }),
+                        hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds: exp_bounds, .. }),
+                    ) if std::iter::zip(*last_bounds, *exp_bounds).all(|(left, right)| {
+                        match (left, right) {
+                            (
+                                hir::GenericBound::Trait(tl, ml),
+                                hir::GenericBound::Trait(tr, mr),
+                            ) if tl.trait_ref.trait_def_id() == tr.trait_ref.trait_def_id()
+                                && ml == mr =>
+                            {
+                                true
+                            }
+                            (
+                                hir::GenericBound::LangItemTrait(langl, _, _, argsl),
+                                hir::GenericBound::LangItemTrait(langr, _, _, argsr),
+                            ) if langl == langr => {
+                                // FIXME: consider the bounds!
+                                debug!("{:?} {:?}", argsl, argsr);
+                                true
+                            }
+                            _ => false,
+                        }
+                    }) =>
+                    {
+                        StatementAsExpression::NeedsBoxing
+                    }
+                    _ => StatementAsExpression::CorrectType,
+                }
+            }
+            _ => return None,
+        };
+        let span = if last_stmt.span.from_expansion() {
+            let mac_call = rustc_span::source_map::original_sp(last_stmt.span, blk.span);
+            self.tcx.sess.source_map().mac_call_stmt_semi_span(mac_call)?
+        } else {
+            last_stmt.span.with_lo(last_stmt.span.hi() - BytePos(1))
+        };
+        Some((span, needs_box))
+    }
+
+    /// Suggest returning a local binding with a compatible type if the block
+    /// has no return expression.
+    pub fn consider_returning_binding(
+        &self,
+        blk: &'tcx hir::Block<'tcx>,
+        expected_ty: Ty<'tcx>,
+        err: &mut Diagnostic,
+    ) -> bool {
+        let blk = blk.innermost_block();
+        // Do not suggest if we have a tail expr.
+        if blk.expr.is_some() {
+            return false;
+        }
+        let mut shadowed = FxIndexSet::default();
+        let mut candidate_idents = vec![];
+        let mut find_compatible_candidates = |pat: &hir::Pat<'_>| {
+            if let hir::PatKind::Binding(_, hir_id, ident, _) = &pat.kind
+                && let Some(pat_ty) = self
+                    .typeck_results
+                    .as_ref()
+                    .and_then(|typeck_results| typeck_results.node_type_opt(*hir_id))
+            {
+                let pat_ty = self.resolve_vars_if_possible(pat_ty);
+                if self.same_type_modulo_infer(pat_ty, expected_ty)
+                    && !(pat_ty, expected_ty).references_error()
+                    && shadowed.insert(ident.name)
+                {
+                    candidate_idents.push((*ident, pat_ty));
+                }
+            }
+            true
+        };
+
+        let hir = self.tcx.hir();
+        for stmt in blk.stmts.iter().rev() {
+            let hir::StmtKind::Local(local) = &stmt.kind else { continue; };
+            local.pat.walk(&mut find_compatible_candidates);
+        }
+        match hir.find(hir.get_parent_node(blk.hir_id)) {
+            Some(hir::Node::Expr(hir::Expr { hir_id, .. })) => {
+                match hir.find(hir.get_parent_node(*hir_id)) {
+                    Some(hir::Node::Arm(hir::Arm { pat, .. })) => {
+                        pat.walk(&mut find_compatible_candidates);
+                    }
+                    Some(
+                        hir::Node::Item(hir::Item { kind: hir::ItemKind::Fn(_, _, body), .. })
+                        | hir::Node::ImplItem(hir::ImplItem {
+                            kind: hir::ImplItemKind::Fn(_, body),
+                            ..
+                        })
+                        | hir::Node::TraitItem(hir::TraitItem {
+                            kind: hir::TraitItemKind::Fn(_, hir::TraitFn::Provided(body)),
+                            ..
+                        })
+                        | hir::Node::Expr(hir::Expr {
+                            kind: hir::ExprKind::Closure(hir::Closure { body, .. }),
+                            ..
+                        }),
+                    ) => {
+                        for param in hir.body(*body).params {
+                            param.pat.walk(&mut find_compatible_candidates);
+                        }
+                    }
+                    Some(hir::Node::Expr(hir::Expr {
+                        kind:
+                            hir::ExprKind::If(
+                                hir::Expr { kind: hir::ExprKind::Let(let_), .. },
+                                then_block,
+                                _,
+                            ),
+                        ..
+                    })) if then_block.hir_id == *hir_id => {
+                        let_.pat.walk(&mut find_compatible_candidates);
+                    }
+                    _ => {}
+                }
+            }
+            _ => {}
+        }
+
+        match &candidate_idents[..] {
+            [(ident, _ty)] => {
+                let sm = self.tcx.sess.source_map();
+                if let Some(stmt) = blk.stmts.last() {
+                    let stmt_span = sm.stmt_span(stmt.span, blk.span);
+                    let sugg = if sm.is_multiline(blk.span)
+                        && let Some(spacing) = sm.indentation_before(stmt_span)
+                    {
+                        format!("\n{spacing}{ident}")
+                    } else {
+                        format!(" {ident}")
+                    };
+                    err.span_suggestion_verbose(
+                        stmt_span.shrink_to_hi(),
+                        format!("consider returning the local binding `{ident}`"),
+                        sugg,
+                        Applicability::MaybeIncorrect,
+                    );
+                } else {
+                    let sugg = if sm.is_multiline(blk.span)
+                        && let Some(spacing) = sm.indentation_before(blk.span.shrink_to_lo())
+                    {
+                        format!("\n{spacing}    {ident}\n{spacing}")
+                    } else {
+                        format!(" {ident} ")
+                    };
+                    let left_span = sm.span_through_char(blk.span, '{').shrink_to_hi();
+                    err.span_suggestion_verbose(
+                        sm.span_extend_while(left_span, |c| c.is_whitespace()).unwrap_or(left_span),
+                        format!("consider returning the local binding `{ident}`"),
+                        sugg,
+                        Applicability::MaybeIncorrect,
+                    );
+                }
+                true
+            }
+            values if (1..3).contains(&values.len()) => {
+                let spans = values.iter().map(|(ident, _)| ident.span).collect::<Vec<_>>();
+                err.span_note(spans, "consider returning one of these bindings");
+                true
+            }
+            _ => false,
+        }
+    }
+}
diff --git a/compiler/rustc_infer/src/infer/note.rs b/compiler/rustc_infer/src/infer/note.rs
new file mode 100644
index 00000000000..2ccbd164faa
--- /dev/null
+++ b/compiler/rustc_infer/src/infer/note.rs
@@ -0,0 +1,203 @@
+impl<'tcx> TypeErrCtxt<'_, 'tcx> {
+    fn note_error_origin(
+        &self,
+        err: &mut Diagnostic,
+        cause: &ObligationCause<'tcx>,
+        exp_found: Option<ty::error::ExpectedFound<Ty<'tcx>>>,
+        terr: TypeError<'tcx>,
+    ) {
+        match *cause.code() {
+            ObligationCauseCode::Pattern { origin_expr: true, span: Some(span), root_ty } => {
+                let ty = self.resolve_vars_if_possible(root_ty);
+                if !matches!(ty.kind(), ty::Infer(ty::InferTy::TyVar(_) | ty::InferTy::FreshTy(_)))
+                {
+                    // don't show type `_`
+                    if span.desugaring_kind() == Some(DesugaringKind::ForLoop)
+                        && let ty::Adt(def, substs) = ty.kind()
+                        && Some(def.did()) == self.tcx.get_diagnostic_item(sym::Option)
+                    {
+                        err.span_label(span, format!("this is an iterator with items of type `{}`", substs.type_at(0)));
+                    } else {
+                    err.span_label(span, format!("this expression has type `{}`", ty));
+                }
+                }
+                if let Some(ty::error::ExpectedFound { found, .. }) = exp_found
+                    && ty.is_box() && ty.boxed_ty() == found
+                    && let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span)
+                {
+                    err.span_suggestion(
+                        span,
+                        "consider dereferencing the boxed value",
+                        format!("*{}", snippet),
+                        Applicability::MachineApplicable,
+                    );
+                }
+            }
+            ObligationCauseCode::Pattern { origin_expr: false, span: Some(span), .. } => {
+                err.span_label(span, "expected due to this");
+            }
+            ObligationCauseCode::MatchExpressionArm(box MatchExpressionArmCause {
+                arm_block_id,
+                arm_span,
+                arm_ty,
+                prior_arm_block_id,
+                prior_arm_span,
+                prior_arm_ty,
+                source,
+                ref prior_arms,
+                scrut_hir_id,
+                opt_suggest_box_span,
+                scrut_span,
+                ..
+            }) => match source {
+                hir::MatchSource::TryDesugar => {
+                    if let Some(ty::error::ExpectedFound { expected, .. }) = exp_found {
+                        let scrut_expr = self.tcx.hir().expect_expr(scrut_hir_id);
+                        let scrut_ty = if let hir::ExprKind::Call(_, args) = &scrut_expr.kind {
+                            let arg_expr = args.first().expect("try desugaring call w/out arg");
+                            self.typeck_results.as_ref().and_then(|typeck_results| {
+                                typeck_results.expr_ty_opt(arg_expr)
+                            })
+                        } else {
+                            bug!("try desugaring w/out call expr as scrutinee");
+                        };
+
+                        match scrut_ty {
+                            Some(ty) if expected == ty => {
+                                let source_map = self.tcx.sess.source_map();
+                                err.span_suggestion(
+                                    source_map.end_point(cause.span),
+                                    "try removing this `?`",
+                                    "",
+                                    Applicability::MachineApplicable,
+                                );
+                            }
+                            _ => {}
+                        }
+                    }
+                }
+                _ => {
+                    // `prior_arm_ty` can be `!`, `expected` will have better info when present.
+                    let t = self.resolve_vars_if_possible(match exp_found {
+                        Some(ty::error::ExpectedFound { expected, .. }) => expected,
+                        _ => prior_arm_ty,
+                    });
+                    let source_map = self.tcx.sess.source_map();
+                    let mut any_multiline_arm = source_map.is_multiline(arm_span);
+                    if prior_arms.len() <= 4 {
+                        for sp in prior_arms {
+                            any_multiline_arm |= source_map.is_multiline(*sp);
+                            err.span_label(*sp, format!("this is found to be of type `{}`", t));
+                        }
+                    } else if let Some(sp) = prior_arms.last() {
+                        any_multiline_arm |= source_map.is_multiline(*sp);
+                        err.span_label(
+                            *sp,
+                            format!("this and all prior arms are found to be of type `{}`", t),
+                        );
+                    }
+                    let outer_error_span = if any_multiline_arm {
+                        // Cover just `match` and the scrutinee expression, not
+                        // the entire match body, to reduce diagram noise.
+                        cause.span.shrink_to_lo().to(scrut_span)
+                    } else {
+                        cause.span
+                    };
+                    let msg = "`match` arms have incompatible types";
+                    err.span_label(outer_error_span, msg);
+                    self.suggest_remove_semi_or_return_binding(
+                        err,
+                        prior_arm_block_id,
+                        prior_arm_ty,
+                        prior_arm_span,
+                        arm_block_id,
+                        arm_ty,
+                        arm_span,
+                    );
+                    if let Some(ret_sp) = opt_suggest_box_span {
+                        // Get return type span and point to it.
+                        self.suggest_boxing_for_return_impl_trait(
+                            err,
+                            ret_sp,
+                            prior_arms.iter().chain(std::iter::once(&arm_span)).map(|s| *s),
+                        );
+                    }
+                }
+            },
+            ObligationCauseCode::IfExpression(box IfExpressionCause {
+                then_id,
+                else_id,
+                then_ty,
+                else_ty,
+                outer_span,
+                opt_suggest_box_span,
+            }) => {
+                let then_span = self.find_block_span_from_hir_id(then_id);
+                let else_span = self.find_block_span_from_hir_id(else_id);
+                err.span_label(then_span, "expected because of this");
+                if let Some(sp) = outer_span {
+                    err.span_label(sp, "`if` and `else` have incompatible types");
+                }
+                self.suggest_remove_semi_or_return_binding(
+                    err,
+                    Some(then_id),
+                    then_ty,
+                    then_span,
+                    Some(else_id),
+                    else_ty,
+                    else_span,
+                );
+                if let Some(ret_sp) = opt_suggest_box_span {
+                    self.suggest_boxing_for_return_impl_trait(
+                        err,
+                        ret_sp,
+                        [then_span, else_span].into_iter(),
+                    );
+                }
+            }
+            ObligationCauseCode::LetElse => {
+                err.help("try adding a diverging expression, such as `return` or `panic!(..)`");
+                err.help("...or use `match` instead of `let...else`");
+            }
+            _ => {
+                if let ObligationCauseCode::BindingObligation(_, span)
+                | ObligationCauseCode::ExprBindingObligation(_, span, ..)
+                = cause.code().peel_derives()
+                    && let TypeError::RegionsPlaceholderMismatch = terr
+                {
+                    err.span_note( * span,
+                    "the lifetime requirement is introduced here");
+                }
+            }
+        }
+    }
+}
+
+impl<'tcx> InferCtxt<'tcx> {
+    /// Given a [`hir::Block`], get the span of its last expression or
+    /// statement, peeling off any inner blocks.
+    pub fn find_block_span(&self, block: &'tcx hir::Block<'tcx>) -> Span {
+        let block = block.innermost_block();
+        if let Some(expr) = &block.expr {
+            expr.span
+        } else if let Some(stmt) = block.stmts.last() {
+            // possibly incorrect trailing `;` in the else arm
+            stmt.span
+        } else {
+            // empty block; point at its entirety
+            block.span
+        }
+    }
+
+    /// Given a [`hir::HirId`] for a block, get the span of its last expression
+    /// or statement, peeling off any inner blocks.
+    pub fn find_block_span_from_hir_id(&self, hir_id: hir::HirId) -> Span {
+        match self.tcx.hir().get(hir_id) {
+            hir::Node::Block(blk) => self.find_block_span(blk),
+            // The parser was in a weird state if either of these happen, but
+            // it's better not to panic.
+            hir::Node::Expr(e) => e.span,
+            _ => rustc_span::DUMMY_SP,
+        }
+    }
+}
diff --git a/compiler/rustc_interface/src/passes.rs b/compiler/rustc_interface/src/passes.rs
index f75c8669fa1..f808c1438bf 100644
--- a/compiler/rustc_interface/src/passes.rs
+++ b/compiler/rustc_interface/src/passes.rs
@@ -158,7 +158,7 @@ pub fn create_resolver(
     sess: Lrc<Session>,
     metadata_loader: Box<MetadataLoaderDyn>,
     krate: &ast::Crate,
-    crate_name: &str,
+    crate_name: Symbol,
 ) -> BoxedResolver {
     trace!("create_resolver");
     BoxedResolver::new(sess, move |sess, resolver_arenas| {
@@ -171,7 +171,7 @@ pub fn register_plugins<'a>(
     metadata_loader: &'a dyn MetadataLoader,
     register_lints: impl Fn(&Session, &mut LintStore),
     mut krate: ast::Crate,
-    crate_name: &str,
+    crate_name: Symbol,
 ) -> Result<(ast::Crate, LintStore)> {
     krate = sess.time("attributes_injection", || {
         rustc_builtin_macros::cmdline_attrs::inject(
@@ -228,19 +228,21 @@ fn pre_expansion_lint<'a>(
     lint_store: &LintStore,
     registered_tools: &RegisteredTools,
     check_node: impl EarlyCheckNode<'a>,
-    node_name: &str,
+    node_name: Symbol,
 ) {
-    sess.prof.generic_activity_with_arg("pre_AST_expansion_lint_checks", node_name).run(|| {
-        rustc_lint::check_ast_node(
-            sess,
-            true,
-            lint_store,
-            registered_tools,
-            None,
-            rustc_lint::BuiltinCombinedPreExpansionLintPass::new(),
-            check_node,
-        );
-    });
+    sess.prof.generic_activity_with_arg("pre_AST_expansion_lint_checks", node_name.as_str()).run(
+        || {
+            rustc_lint::check_ast_node(
+                sess,
+                true,
+                lint_store,
+                registered_tools,
+                None,
+                rustc_lint::BuiltinCombinedPreExpansionLintPass::new(),
+                check_node,
+            );
+        },
+    );
 }
 
 // Cannot implement directly for `LintStore` due to trait coherence.
@@ -254,7 +256,7 @@ impl LintStoreExpand for LintStoreExpandImpl<'_> {
         node_id: ast::NodeId,
         attrs: &[ast::Attribute],
         items: &[rustc_ast::ptr::P<ast::Item>],
-        name: &str,
+        name: Symbol,
     ) {
         pre_expansion_lint(sess, self.0, registered_tools, (node_id, attrs, items), name);
     }
@@ -268,7 +270,7 @@ pub fn configure_and_expand(
     sess: &Session,
     lint_store: &LintStore,
     mut krate: ast::Crate,
-    crate_name: &str,
+    crate_name: Symbol,
     resolver: &mut Resolver<'_>,
 ) -> Result<ast::Crate> {
     trace!("configure_and_expand");
@@ -462,7 +464,7 @@ fn generated_output_paths(
     sess: &Session,
     outputs: &OutputFilenames,
     exact_name: bool,
-    crate_name: &str,
+    crate_name: Symbol,
 ) -> Vec<PathBuf> {
     let mut out_filenames = Vec::new();
     for output_type in sess.opts.output_types.keys() {
@@ -661,7 +663,7 @@ pub fn prepare_outputs(
     compiler: &Compiler,
     krate: &ast::Crate,
     boxed_resolver: &RefCell<BoxedResolver>,
-    crate_name: &str,
+    crate_name: Symbol,
 ) -> Result<OutputFilenames> {
     let _timer = sess.timer("prepare_outputs");
 
@@ -771,7 +773,7 @@ pub fn create_global_ctxt<'tcx>(
     dep_graph: DepGraph,
     resolver: Rc<RefCell<BoxedResolver>>,
     outputs: OutputFilenames,
-    crate_name: &str,
+    crate_name: Symbol,
     queries: &'tcx OnceCell<TcxQueries<'tcx>>,
     global_ctxt: &'tcx OnceCell<GlobalCtxt<'tcx>>,
     arena: &'tcx WorkerLocal<Arena<'tcx>>,
diff --git a/compiler/rustc_interface/src/queries.rs b/compiler/rustc_interface/src/queries.rs
index f5ddd647b24..39e1f2204b0 100644
--- a/compiler/rustc_interface/src/queries.rs
+++ b/compiler/rustc_interface/src/queries.rs
@@ -17,6 +17,7 @@ use rustc_query_impl::Queries as TcxQueries;
 use rustc_session::config::{self, OutputFilenames, OutputType};
 use rustc_session::{output::find_crate_name, Session};
 use rustc_span::symbol::sym;
+use rustc_span::Symbol;
 use std::any::Any;
 use std::cell::{Ref, RefCell, RefMut};
 use std::rc::Rc;
@@ -74,7 +75,7 @@ pub struct Queries<'tcx> {
 
     dep_graph_future: Query<Option<DepGraphFuture>>,
     parse: Query<ast::Crate>,
-    crate_name: Query<String>,
+    crate_name: Query<Symbol>,
     register_plugins: Query<(ast::Crate, Lrc<LintStore>)>,
     expansion: Query<(Lrc<ast::Crate>, Rc<RefCell<BoxedResolver>>, Lrc<LintStore>)>,
     dep_graph: Query<DepGraph>,
@@ -135,7 +136,7 @@ impl<'tcx> Queries<'tcx> {
                 &*self.codegen_backend().metadata_loader(),
                 self.compiler.register_lints.as_deref().unwrap_or_else(|| empty),
                 krate,
-                &crate_name,
+                crate_name,
             )?;
 
             // Compute the dependency graph (in the background). We want to do
@@ -149,7 +150,7 @@ impl<'tcx> Queries<'tcx> {
         })
     }
 
-    pub fn crate_name(&self) -> Result<&Query<String>> {
+    pub fn crate_name(&self) -> Result<&Query<Symbol>> {
         self.crate_name.compute(|| {
             Ok({
                 let parse_result = self.parse()?;
@@ -165,7 +166,7 @@ impl<'tcx> Queries<'tcx> {
     ) -> Result<&Query<(Lrc<ast::Crate>, Rc<RefCell<BoxedResolver>>, Lrc<LintStore>)>> {
         trace!("expansion");
         self.expansion.compute(|| {
-            let crate_name = self.crate_name()?.peek().clone();
+            let crate_name = *self.crate_name()?.peek();
             let (krate, lint_store) = self.register_plugins()?.take();
             let _timer = self.session().timer("configure_and_expand");
             let sess = self.session();
@@ -173,10 +174,10 @@ impl<'tcx> Queries<'tcx> {
                 sess.clone(),
                 self.codegen_backend().metadata_loader(),
                 &krate,
-                &crate_name,
+                crate_name,
             );
             let krate = resolver.access(|resolver| {
-                passes::configure_and_expand(sess, &lint_store, krate, &crate_name, resolver)
+                passes::configure_and_expand(sess, &lint_store, krate, crate_name, resolver)
             })?;
             Ok((Lrc::new(krate), Rc::new(RefCell::new(resolver)), lint_store))
         })
@@ -201,20 +202,20 @@ impl<'tcx> Queries<'tcx> {
     pub fn prepare_outputs(&self) -> Result<&Query<OutputFilenames>> {
         self.prepare_outputs.compute(|| {
             let (krate, boxed_resolver, _) = &*self.expansion()?.peek();
-            let crate_name = self.crate_name()?.peek();
+            let crate_name = *self.crate_name()?.peek();
             passes::prepare_outputs(
                 self.session(),
                 self.compiler,
                 krate,
                 &*boxed_resolver,
-                &crate_name,
+                crate_name,
             )
         })
     }
 
     pub fn global_ctxt(&'tcx self) -> Result<&Query<QueryContext<'tcx>>> {
         self.global_ctxt.compute(|| {
-            let crate_name = self.crate_name()?.peek().clone();
+            let crate_name = *self.crate_name()?.peek();
             let outputs = self.prepare_outputs()?.take();
             let dep_graph = self.dep_graph()?.peek().clone();
             let (krate, resolver, lint_store) = self.expansion()?.take();
@@ -225,7 +226,7 @@ impl<'tcx> Queries<'tcx> {
                 dep_graph,
                 resolver,
                 outputs,
-                &crate_name,
+                crate_name,
                 &self.queries,
                 &self.gcx,
                 &self.arena,
diff --git a/compiler/rustc_metadata/src/creader.rs b/compiler/rustc_metadata/src/creader.rs
index 1a2389c7a84..efeaac8fe9a 100644
--- a/compiler/rustc_metadata/src/creader.rs
+++ b/compiler/rustc_metadata/src/creader.rs
@@ -245,7 +245,7 @@ impl<'a> CrateLoader<'a> {
     pub fn new(
         sess: &'a Session,
         metadata_loader: Box<MetadataLoaderDyn>,
-        local_crate_name: &str,
+        local_crate_name: Symbol,
     ) -> Self {
         let mut stable_crate_ids = FxHashMap::default();
         stable_crate_ids.insert(sess.local_stable_crate_id(), LOCAL_CRATE);
@@ -253,7 +253,7 @@ impl<'a> CrateLoader<'a> {
         CrateLoader {
             sess,
             metadata_loader,
-            local_crate_name: Symbol::intern(local_crate_name),
+            local_crate_name,
             cstore: CStore {
                 // We add an empty entry for LOCAL_CRATE (which maps to zero) in
                 // order to make array indices in `metas` match with the
@@ -1000,7 +1000,7 @@ impl<'a> CrateLoader<'a> {
                 );
                 let name = match orig_name {
                     Some(orig_name) => {
-                        validate_crate_name(self.sess, orig_name.as_str(), Some(item.span));
+                        validate_crate_name(self.sess, orig_name, Some(item.span));
                         orig_name
                     }
                     None => item.ident.name,
diff --git a/compiler/rustc_metadata/src/fs.rs b/compiler/rustc_metadata/src/fs.rs
index 4fa440c7ca6..7601f6bd322 100644
--- a/compiler/rustc_metadata/src/fs.rs
+++ b/compiler/rustc_metadata/src/fs.rs
@@ -61,8 +61,7 @@ pub fn encode_and_write_metadata(tcx: TyCtxt<'_>) -> (EncodedMetadata, bool) {
         .unwrap_or(MetadataKind::None);
 
     let crate_name = tcx.crate_name(LOCAL_CRATE);
-    let out_filename =
-        filename_for_metadata(tcx.sess, crate_name.as_str(), tcx.output_filenames(()));
+    let out_filename = filename_for_metadata(tcx.sess, crate_name, tcx.output_filenames(()));
     // To avoid races with another rustc process scanning the output directory,
     // we need to write the file somewhere else and atomically move it to its
     // final destination, with an `fs::rename` call. In order for the rename to
diff --git a/compiler/rustc_middle/src/mir/syntax.rs b/compiler/rustc_middle/src/mir/syntax.rs
index 988d27ba262..5ba053820e0 100644
--- a/compiler/rustc_middle/src/mir/syntax.rs
+++ b/compiler/rustc_middle/src/mir/syntax.rs
@@ -408,7 +408,7 @@ impl std::fmt::Display for NonDivergingIntrinsic<'_> {
 #[derive(Copy, Clone, TyEncodable, TyDecodable, Debug, PartialEq, Eq, Hash, HashStable)]
 #[rustc_pass_by_value]
 pub enum RetagKind {
-    /// The initial retag when entering a function.
+    /// The initial retag of arguments when entering a function.
     FnEntry,
     /// Retag preparing for a two-phase borrow.
     TwoPhase,
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index af573376a26..b44bc14ec26 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -1285,7 +1285,7 @@ impl<'tcx> TyCtxt<'tcx> {
         on_disk_cache: Option<&'tcx dyn OnDiskCache<'tcx>>,
         queries: &'tcx dyn query::QueryEngine<'tcx>,
         query_kinds: &'tcx [DepKindStruct<'tcx>],
-        crate_name: &str,
+        crate_name: Symbol,
         output_filenames: OutputFilenames,
     ) -> GlobalCtxt<'tcx> {
         let data_layout = s.target.parse_data_layout().unwrap_or_else(|err| {
@@ -1325,7 +1325,7 @@ impl<'tcx> TyCtxt<'tcx> {
             pred_rcache: Default::default(),
             selection_cache: Default::default(),
             evaluation_cache: Default::default(),
-            crate_name: Symbol::intern(crate_name),
+            crate_name,
             data_layout,
             alloc_map: Lock::new(interpret::AllocMap::new()),
             output_filenames: Arc::new(output_filenames),
diff --git a/compiler/rustc_middle/src/ty/error.rs b/compiler/rustc_middle/src/ty/error.rs
index d83e17574a0..aa61c39b8d8 100644
--- a/compiler/rustc_middle/src/ty/error.rs
+++ b/compiler/rustc_middle/src/ty/error.rs
@@ -986,23 +986,32 @@ fn foo(&self) -> Self::T { String::new() }
     }
 
     pub fn short_ty_string(self, ty: Ty<'tcx>) -> (String, Option<PathBuf>) {
-        let length_limit = 50;
-        let type_limit = 4;
+        let width = self.sess.diagnostic_width();
+        let length_limit = width.saturating_sub(30);
+        let mut type_limit = 50;
         let regular = FmtPrinter::new(self, hir::def::Namespace::TypeNS)
             .pretty_print_type(ty)
             .expect("could not write to `String`")
             .into_buffer();
-        if regular.len() <= length_limit {
+        if regular.len() <= width {
             return (regular, None);
         }
-        let short = FmtPrinter::new_with_limit(
-            self,
-            hir::def::Namespace::TypeNS,
-            rustc_session::Limit(type_limit),
-        )
-        .pretty_print_type(ty)
-        .expect("could not write to `String`")
-        .into_buffer();
+        let mut short;
+        loop {
+            // Look for the longest properly trimmed path that still fits in lenght_limit.
+            short = FmtPrinter::new_with_limit(
+                self,
+                hir::def::Namespace::TypeNS,
+                rustc_session::Limit(type_limit),
+            )
+            .pretty_print_type(ty)
+            .expect("could not write to `String`")
+            .into_buffer();
+            if short.len() <= length_limit || type_limit == 0 {
+                break;
+            }
+            type_limit -= 1;
+        }
         if regular == short {
             return (regular, None);
         }
diff --git a/compiler/rustc_mir_transform/src/add_retag.rs b/compiler/rustc_mir_transform/src/add_retag.rs
index 036b5589849..3d22035f078 100644
--- a/compiler/rustc_mir_transform/src/add_retag.rs
+++ b/compiler/rustc_mir_transform/src/add_retag.rs
@@ -10,16 +10,6 @@ use rustc_middle::ty::{self, Ty, TyCtxt};
 
 pub struct AddRetag;
 
-/// Determines whether this place is "stable": Whether, if we evaluate it again
-/// after the assignment, we can be sure to obtain the same place value.
-/// (Concurrent accesses by other threads are no problem as these are anyway non-atomic
-/// copies.  Data races are UB.)
-fn is_stable(place: PlaceRef<'_>) -> bool {
-    // Which place this evaluates to can change with any memory write,
-    // so cannot assume deref to be stable.
-    !place.has_deref()
-}
-
 /// Determine whether this type may contain a reference (or box), and thus needs retagging.
 /// We will only recurse `depth` times into Tuples/ADTs to bound the cost of this.
 fn may_contain_reference<'tcx>(ty: Ty<'tcx>, depth: u32, tcx: TyCtxt<'tcx>) -> bool {
@@ -69,22 +59,10 @@ impl<'tcx> MirPass<'tcx> for AddRetag {
         let basic_blocks = body.basic_blocks.as_mut();
         let local_decls = &body.local_decls;
         let needs_retag = |place: &Place<'tcx>| {
-            // FIXME: Instead of giving up for unstable places, we should introduce
-            // a temporary and retag on that.
-            is_stable(place.as_ref())
+            !place.has_deref() // we're not eally interested in stores to "outside" locations, they are hard to keep track of anyway
                 && may_contain_reference(place.ty(&*local_decls, tcx).ty, /*depth*/ 3, tcx)
                 && !local_decls[place.local].is_deref_temp()
         };
-        let place_base_raw = |place: &Place<'tcx>| {
-            // If this is a `Deref`, get the type of what we are deref'ing.
-            if place.has_deref() {
-                let ty = &local_decls[place.local].ty;
-                ty.is_unsafe_ptr()
-            } else {
-                // Not a deref, and thus not raw.
-                false
-            }
-        };
 
         // PART 1
         // Retag arguments at the beginning of the start block.
@@ -108,7 +86,7 @@ impl<'tcx> MirPass<'tcx> for AddRetag {
         }
 
         // PART 2
-        // Retag return values of functions.  Also escape-to-raw the argument of `drop`.
+        // Retag return values of functions.
         // We collect the return destinations because we cannot mutate while iterating.
         let returns = basic_blocks
             .iter_mut()
@@ -140,30 +118,25 @@ impl<'tcx> MirPass<'tcx> for AddRetag {
         }
 
         // PART 3
-        // Add retag after assignment.
+        // Add retag after assignments where data "enters" this function: the RHS is behind a deref and the LHS is not.
         for block_data in basic_blocks {
             // We want to insert statements as we iterate.  To this end, we
             // iterate backwards using indices.
             for i in (0..block_data.statements.len()).rev() {
                 let (retag_kind, place) = match block_data.statements[i].kind {
-                    // Retag-as-raw after escaping to a raw pointer, if the referent
-                    // is not already a raw pointer.
-                    StatementKind::Assign(box (lplace, Rvalue::AddressOf(_, ref rplace)))
-                        if !place_base_raw(rplace) =>
-                    {
-                        (RetagKind::Raw, lplace)
-                    }
                     // Retag after assignments of reference type.
                     StatementKind::Assign(box (ref place, ref rvalue)) if needs_retag(place) => {
-                        let kind = match rvalue {
-                            Rvalue::Ref(_, borrow_kind, _)
-                                if borrow_kind.allows_two_phase_borrow() =>
-                            {
-                                RetagKind::TwoPhase
-                            }
-                            _ => RetagKind::Default,
+                        let add_retag = match rvalue {
+                            // Ptr-creating operations already do their own internal retagging, no
+                            // need to also add a retag statement.
+                            Rvalue::Ref(..) | Rvalue::AddressOf(..) => false,
+                            _ => true,
                         };
-                        (kind, *place)
+                        if add_retag {
+                            (RetagKind::Default, *place)
+                        } else {
+                            continue;
+                        }
                     }
                     // Do nothing for the rest
                     _ => continue,
diff --git a/compiler/rustc_mir_transform/src/generator.rs b/compiler/rustc_mir_transform/src/generator.rs
index 8922298ecaf..69f96fe48ea 100644
--- a/compiler/rustc_mir_transform/src/generator.rs
+++ b/compiler/rustc_mir_transform/src/generator.rs
@@ -985,16 +985,6 @@ fn create_generator_drop_shim<'tcx>(
         tcx.mk_ptr(ty::TypeAndMut { ty: gen_ty, mutbl: hir::Mutability::Mut }),
         source_info,
     );
-    if tcx.sess.opts.unstable_opts.mir_emit_retag {
-        // Alias tracking must know we changed the type
-        body.basic_blocks_mut()[START_BLOCK].statements.insert(
-            0,
-            Statement {
-                source_info,
-                kind: StatementKind::Retag(RetagKind::Raw, Box::new(Place::from(SELF_ARG))),
-            },
-        )
-    }
 
     // Make sure we remove dead blocks to remove
     // unrelated code from the resume part of the function
diff --git a/compiler/rustc_mir_transform/src/shim.rs b/compiler/rustc_mir_transform/src/shim.rs
index a115bb2831a..16b7dcad17e 100644
--- a/compiler/rustc_mir_transform/src/shim.rs
+++ b/compiler/rustc_mir_transform/src/shim.rs
@@ -177,16 +177,6 @@ fn build_drop_shim<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, ty: Option<Ty<'tcx>>)
     if ty.is_some() {
         // The first argument (index 0), but add 1 for the return value.
         let dropee_ptr = Place::from(Local::new(1 + 0));
-        if tcx.sess.opts.unstable_opts.mir_emit_retag {
-            // Function arguments should be retagged, and we make this one raw.
-            body.basic_blocks_mut()[START_BLOCK].statements.insert(
-                0,
-                Statement {
-                    source_info,
-                    kind: StatementKind::Retag(RetagKind::Raw, Box::new(dropee_ptr)),
-                },
-            );
-        }
         let patch = {
             let param_env = tcx.param_env_reveal_all_normalized(def_id);
             let mut elaborator =
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index 4ef89cfb255..82f5d0f534a 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -1196,7 +1196,7 @@ impl<'a> Resolver<'a> {
     pub fn new(
         session: &'a Session,
         krate: &Crate,
-        crate_name: &str,
+        crate_name: Symbol,
         metadata_loader: Box<MetadataLoaderDyn>,
         arenas: &'a ResolverArenas<'a>,
     ) -> Resolver<'a> {
diff --git a/compiler/rustc_save_analysis/src/dump_visitor.rs b/compiler/rustc_save_analysis/src/dump_visitor.rs
index b4528853825..9ae07cb005b 100644
--- a/compiler/rustc_save_analysis/src/dump_visitor.rs
+++ b/compiler/rustc_save_analysis/src/dump_visitor.rs
@@ -111,7 +111,7 @@ impl<'tcx> DumpVisitor<'tcx> {
         self.save_ctxt.lookup_def_id(ref_id)
     }
 
-    pub fn dump_crate_info(&mut self, name: &str) {
+    pub fn dump_crate_info(&mut self, name: Symbol) {
         let source_file = self.tcx.sess.local_crate_source_file.as_ref();
         let crate_root = source_file.map(|source_file| {
             let source_file = Path::new(source_file);
@@ -124,7 +124,7 @@ impl<'tcx> DumpVisitor<'tcx> {
 
         let data = CratePreludeData {
             crate_id: GlobalCrateId {
-                name: name.into(),
+                name: name.to_string(),
                 disambiguator: (self.tcx.sess.local_stable_crate_id().to_u64(), 0),
             },
             crate_root: crate_root.unwrap_or_else(|| "<no source>".to_owned()),
@@ -135,7 +135,7 @@ impl<'tcx> DumpVisitor<'tcx> {
         self.dumper.crate_prelude(data);
     }
 
-    pub fn dump_compilation_options(&mut self, input: &Input, crate_name: &str) {
+    pub fn dump_compilation_options(&mut self, input: &Input, crate_name: Symbol) {
         // Apply possible `remap-path-prefix` remapping to the input source file
         // (and don't include remapping args anymore)
         let (program, arguments) = {
diff --git a/compiler/rustc_save_analysis/src/lib.rs b/compiler/rustc_save_analysis/src/lib.rs
index f05eb2b7432..7735c571310 100644
--- a/compiler/rustc_save_analysis/src/lib.rs
+++ b/compiler/rustc_save_analysis/src/lib.rs
@@ -95,7 +95,7 @@ impl<'tcx> SaveContext<'tcx> {
     }
 
     /// Returns path to the compilation output (e.g., libfoo-12345678.rmeta)
-    pub fn compilation_output(&self, crate_name: &str) -> PathBuf {
+    pub fn compilation_output(&self, crate_name: Symbol) -> PathBuf {
         let sess = &self.tcx.sess;
         // Save-analysis is emitted per whole session, not per each crate type
         let crate_type = sess.crate_types()[0];
@@ -894,8 +894,8 @@ pub struct DumpHandler<'a> {
 }
 
 impl<'a> DumpHandler<'a> {
-    pub fn new(odir: Option<&'a Path>, cratename: &str) -> DumpHandler<'a> {
-        DumpHandler { odir, cratename: cratename.to_owned() }
+    pub fn new(odir: Option<&'a Path>, cratename: Symbol) -> DumpHandler<'a> {
+        DumpHandler { odir, cratename: cratename.to_string() }
     }
 
     fn output_file(&self, ctx: &SaveContext<'_>) -> (BufWriter<File>, PathBuf) {
@@ -960,7 +960,7 @@ impl SaveHandler for CallbackHandler<'_> {
 
 pub fn process_crate<'l, 'tcx, H: SaveHandler>(
     tcx: TyCtxt<'tcx>,
-    cratename: &str,
+    cratename: Symbol,
     input: &'l Input,
     config: Option<Config>,
     mut handler: H,
diff --git a/compiler/rustc_session/Cargo.toml b/compiler/rustc_session/Cargo.toml
index a052f293341..cbbba2252bf 100644
--- a/compiler/rustc_session/Cargo.toml
+++ b/compiler/rustc_session/Cargo.toml
@@ -18,6 +18,7 @@ rustc_fs_util = { path = "../rustc_fs_util" }
 rustc_ast = { path = "../rustc_ast" }
 rustc_lint_defs = { path = "../rustc_lint_defs" }
 smallvec = "1.8.1"
+termize = "0.1.1"
 
 [target.'cfg(unix)'.dependencies]
 libc = "0.2"
diff --git a/compiler/rustc_session/src/errors.rs b/compiler/rustc_session/src/errors.rs
index 8cb9e1a6f1a..ee492f802a7 100644
--- a/compiler/rustc_session/src/errors.rs
+++ b/compiler/rustc_session/src/errors.rs
@@ -129,10 +129,10 @@ pub struct FileIsNotWriteable<'a> {
 
 #[derive(Diagnostic)]
 #[diag(session_crate_name_does_not_match)]
-pub struct CrateNameDoesNotMatch<'a> {
+pub struct CrateNameDoesNotMatch {
     #[primary_span]
     pub span: Span,
-    pub s: &'a str,
+    pub s: Symbol,
     pub name: Symbol,
 }
 
@@ -151,11 +151,11 @@ pub struct CrateNameEmpty {
 
 #[derive(Diagnostic)]
 #[diag(session_invalid_character_in_create_name)]
-pub struct InvalidCharacterInCrateName<'a> {
+pub struct InvalidCharacterInCrateName {
     #[primary_span]
     pub span: Option<Span>,
     pub character: char,
-    pub crate_name: &'a str,
+    pub crate_name: Symbol,
 }
 
 #[derive(Subdiagnostic)]
diff --git a/compiler/rustc_session/src/output.rs b/compiler/rustc_session/src/output.rs
index 2511bee46af..8ee3057de62 100644
--- a/compiler/rustc_session/src/output.rs
+++ b/compiler/rustc_session/src/output.rs
@@ -7,14 +7,14 @@ use crate::errors::{
 use crate::Session;
 use rustc_ast as ast;
 use rustc_span::symbol::sym;
-use rustc_span::Span;
+use rustc_span::{Span, Symbol};
 use std::path::{Path, PathBuf};
 
 pub fn out_filename(
     sess: &Session,
     crate_type: CrateType,
     outputs: &OutputFilenames,
-    crate_name: &str,
+    crate_name: Symbol,
 ) -> PathBuf {
     let default_filename = filename_for_input(sess, crate_type, crate_name, outputs);
     let out_filename = outputs
@@ -45,9 +45,9 @@ fn is_writeable(p: &Path) -> bool {
     }
 }
 
-pub fn find_crate_name(sess: &Session, attrs: &[ast::Attribute], input: &Input) -> String {
-    let validate = |s: String, span: Option<Span>| {
-        validate_crate_name(sess, &s, span);
+pub fn find_crate_name(sess: &Session, attrs: &[ast::Attribute], input: &Input) -> Symbol {
+    let validate = |s: Symbol, span: Option<Span>| {
+        validate_crate_name(sess, s, span);
         s
     };
 
@@ -59,38 +59,39 @@ pub fn find_crate_name(sess: &Session, attrs: &[ast::Attribute], input: &Input)
         sess.find_by_name(attrs, sym::crate_name).and_then(|at| at.value_str().map(|s| (at, s)));
 
     if let Some(ref s) = sess.opts.crate_name {
+        let s = Symbol::intern(s);
         if let Some((attr, name)) = attr_crate_name {
-            if name.as_str() != s {
+            if name != s {
                 sess.emit_err(CrateNameDoesNotMatch { span: attr.span, s, name });
             }
         }
-        return validate(s.clone(), None);
+        return validate(s, None);
     }
 
     if let Some((attr, s)) = attr_crate_name {
-        return validate(s.to_string(), Some(attr.span));
+        return validate(s, Some(attr.span));
     }
     if let Input::File(ref path) = *input {
         if let Some(s) = path.file_stem().and_then(|s| s.to_str()) {
             if s.starts_with('-') {
                 sess.emit_err(CrateNameInvalid { s });
             } else {
-                return validate(s.replace('-', "_"), None);
+                return validate(Symbol::intern(&s.replace('-', "_")), None);
             }
         }
     }
 
-    "rust_out".to_string()
+    Symbol::intern("rust_out")
 }
 
-pub fn validate_crate_name(sess: &Session, s: &str, sp: Option<Span>) {
+pub fn validate_crate_name(sess: &Session, s: Symbol, sp: Option<Span>) {
     let mut err_count = 0;
     {
         if s.is_empty() {
             err_count += 1;
             sess.emit_err(CrateNameEmpty { span: sp });
         }
-        for c in s.chars() {
+        for c in s.as_str().chars() {
             if c.is_alphanumeric() {
                 continue;
             }
@@ -109,7 +110,7 @@ pub fn validate_crate_name(sess: &Session, s: &str, sp: Option<Span>) {
 
 pub fn filename_for_metadata(
     sess: &Session,
-    crate_name: &str,
+    crate_name: Symbol,
     outputs: &OutputFilenames,
 ) -> PathBuf {
     // If the command-line specified the path, use that directly.
@@ -132,7 +133,7 @@ pub fn filename_for_metadata(
 pub fn filename_for_input(
     sess: &Session,
     crate_type: CrateType,
-    crate_name: &str,
+    crate_name: Symbol,
     outputs: &OutputFilenames,
 ) -> PathBuf {
     let libname = format!("{}{}", crate_name, sess.opts.cg.extra_filename);
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index e99e460913e..4c049a8d628 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -952,6 +952,17 @@ impl Session {
     ) -> Option<Symbol> {
         attrs.iter().find(|at| at.has_name(name)).and_then(|at| at.value_str())
     }
+
+    pub fn diagnostic_width(&self) -> usize {
+        let default_column_width = 140;
+        if let Some(width) = self.opts.diagnostic_width {
+            width
+        } else if self.opts.unstable_opts.ui_testing {
+            default_column_width
+        } else {
+            termize::dimensions().map_or(default_column_width, |(w, _)| w)
+        }
+    }
 }
 
 // JUSTIFICATION: defn of the suggested wrapper fns
diff --git a/compiler/rustc_span/src/def_id.rs b/compiler/rustc_span/src/def_id.rs
index 0ad1f1a0da7..e62ce2c266a 100644
--- a/compiler/rustc_span/src/def_id.rs
+++ b/compiler/rustc_span/src/def_id.rs
@@ -1,4 +1,4 @@
-use crate::HashStableContext;
+use crate::{HashStableContext, Symbol};
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey};
 use rustc_data_structures::AtomicRef;
@@ -149,9 +149,11 @@ impl StableCrateId {
 
     /// Computes the stable ID for a crate with the given name and
     /// `-Cmetadata` arguments.
-    pub fn new(crate_name: &str, is_exe: bool, mut metadata: Vec<String>) -> StableCrateId {
+    pub fn new(crate_name: Symbol, is_exe: bool, mut metadata: Vec<String>) -> StableCrateId {
         let mut hasher = StableHasher::new();
-        crate_name.hash(&mut hasher);
+        // We must hash the string text of the crate name, not the id, as the id is not stable
+        // across builds.
+        crate_name.as_str().hash(&mut hasher);
 
         // We don't want the stable crate ID to depend on the order of
         // -C metadata arguments, so sort them:
diff --git a/compiler/rustc_target/src/spec/wasm32_unknown_unknown.rs b/compiler/rustc_target/src/spec/wasm32_unknown_unknown.rs
index 8dad941b534..06529c2e403 100644
--- a/compiler/rustc_target/src/spec/wasm32_unknown_unknown.rs
+++ b/compiler/rustc_target/src/spec/wasm32_unknown_unknown.rs
@@ -33,12 +33,6 @@ pub fn target() -> Target {
             // For now this target just never has an entry symbol no matter the output
             // type, so unconditionally pass this.
             "--no-entry",
-            // Rust really needs a way for users to specify exports and imports in
-            // the source code. --export-dynamic isn't the right tool for this job,
-            // however it does have the side effect of automatically exporting a lot
-            // of symbols, which approximates what people want when compiling for
-            // wasm32-unknown-unknown expect, so use it for now.
-            "--export-dynamic",
         ],
     );
     options.add_pre_link_args(
@@ -48,7 +42,6 @@ pub fn target() -> Target {
             // otherwise
             "--target=wasm32-unknown-unknown",
             "-Wl,--no-entry",
-            "-Wl,--export-dynamic",
         ],
     );
 
diff --git a/compiler/rustc_trait_selection/src/traits/mod.rs b/compiler/rustc_trait_selection/src/traits/mod.rs
index d3cfd61e195..ea4bf42c515 100644
--- a/compiler/rustc_trait_selection/src/traits/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/mod.rs
@@ -4,7 +4,6 @@
 
 pub mod auto_trait;
 mod chalk_fulfill;
-pub mod codegen;
 mod coherence;
 pub mod const_evaluatable;
 mod engine;
@@ -20,9 +19,9 @@ mod select;
 mod specialize;
 mod structural_match;
 mod util;
+mod vtable;
 pub mod wf;
 
-use crate::errors::DumpVTableEntries;
 use crate::infer::outlives::env::OutlivesEnvironment;
 use crate::infer::{InferCtxt, TyCtxtInferExt};
 use crate::traits::error_reporting::TypeErrCtxtExt as _;
@@ -30,15 +29,11 @@ use crate::traits::query::evaluate_obligation::InferCtxtExt as _;
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
-use rustc_hir::lang_items::LangItem;
 use rustc_middle::ty::fold::TypeFoldable;
 use rustc_middle::ty::visit::TypeVisitable;
-use rustc_middle::ty::{
-    self, DefIdTree, GenericParamDefKind, ToPredicate, Ty, TyCtxt, TypeSuperVisitable, VtblEntry,
-};
+use rustc_middle::ty::{self, DefIdTree, ToPredicate, Ty, TyCtxt, TypeSuperVisitable};
 use rustc_middle::ty::{InternalSubsts, SubstsRef};
-use rustc_span::{sym, Span};
-use smallvec::SmallVec;
+use rustc_span::Span;
 
 use std::fmt::Debug;
 use std::ops::ControlFlow;
@@ -567,369 +562,12 @@ fn is_impossible_method<'tcx>(
     false
 }
 
-#[derive(Clone, Debug)]
-enum VtblSegment<'tcx> {
-    MetadataDSA,
-    TraitOwnEntries { trait_ref: ty::PolyTraitRef<'tcx>, emit_vptr: bool },
-}
-
-/// Prepare the segments for a vtable
-fn prepare_vtable_segments<'tcx, T>(
-    tcx: TyCtxt<'tcx>,
-    trait_ref: ty::PolyTraitRef<'tcx>,
-    mut segment_visitor: impl FnMut(VtblSegment<'tcx>) -> ControlFlow<T>,
-) -> Option<T> {
-    // The following constraints holds for the final arrangement.
-    // 1. The whole virtual table of the first direct super trait is included as the
-    //    the prefix. If this trait doesn't have any super traits, then this step
-    //    consists of the dsa metadata.
-    // 2. Then comes the proper pointer metadata(vptr) and all own methods for all
-    //    other super traits except those already included as part of the first
-    //    direct super trait virtual table.
-    // 3. finally, the own methods of this trait.
-
-    // This has the advantage that trait upcasting to the first direct super trait on each level
-    // is zero cost, and to another trait includes only replacing the pointer with one level indirection,
-    // while not using too much extra memory.
-
-    // For a single inheritance relationship like this,
-    //   D --> C --> B --> A
-    // The resulting vtable will consists of these segments:
-    //  DSA, A, B, C, D
-
-    // For a multiple inheritance relationship like this,
-    //   D --> C --> A
-    //           \-> B
-    // The resulting vtable will consists of these segments:
-    //  DSA, A, B, B-vptr, C, D
-
-    // For a diamond inheritance relationship like this,
-    //   D --> B --> A
-    //     \-> C -/
-    // The resulting vtable will consists of these segments:
-    //  DSA, A, B, C, C-vptr, D
-
-    // For a more complex inheritance relationship like this:
-    //   O --> G --> C --> A
-    //     \     \     \-> B
-    //     |     |-> F --> D
-    //     |           \-> E
-    //     |-> N --> J --> H
-    //           \     \-> I
-    //           |-> M --> K
-    //                 \-> L
-    // The resulting vtable will consists of these segments:
-    //  DSA, A, B, B-vptr, C, D, D-vptr, E, E-vptr, F, F-vptr, G,
-    //  H, H-vptr, I, I-vptr, J, J-vptr, K, K-vptr, L, L-vptr, M, M-vptr,
-    //  N, N-vptr, O
-
-    // emit dsa segment first.
-    if let ControlFlow::Break(v) = (segment_visitor)(VtblSegment::MetadataDSA) {
-        return Some(v);
-    }
-
-    let mut emit_vptr_on_new_entry = false;
-    let mut visited = util::PredicateSet::new(tcx);
-    let predicate = trait_ref.without_const().to_predicate(tcx);
-    let mut stack: SmallVec<[(ty::PolyTraitRef<'tcx>, _, _); 5]> =
-        smallvec![(trait_ref, emit_vptr_on_new_entry, None)];
-    visited.insert(predicate);
-
-    // the main traversal loop:
-    // basically we want to cut the inheritance directed graph into a few non-overlapping slices of nodes
-    // that each node is emitted after all its descendents have been emitted.
-    // so we convert the directed graph into a tree by skipping all previously visited nodes using a visited set.
-    // this is done on the fly.
-    // Each loop run emits a slice - it starts by find a "childless" unvisited node, backtracking upwards, and it
-    // stops after it finds a node that has a next-sibling node.
-    // This next-sibling node will used as the starting point of next slice.
-
-    // Example:
-    // For a diamond inheritance relationship like this,
-    //   D#1 --> B#0 --> A#0
-    //     \-> C#1 -/
-
-    // Starting point 0 stack [D]
-    // Loop run #0: Stack after diving in is [D B A], A is "childless"
-    // after this point, all newly visited nodes won't have a vtable that equals to a prefix of this one.
-    // Loop run #0: Emitting the slice [B A] (in reverse order), B has a next-sibling node, so this slice stops here.
-    // Loop run #0: Stack after exiting out is [D C], C is the next starting point.
-    // Loop run #1: Stack after diving in is [D C], C is "childless", since its child A is skipped(already emitted).
-    // Loop run #1: Emitting the slice [D C] (in reverse order). No one has a next-sibling node.
-    // Loop run #1: Stack after exiting out is []. Now the function exits.
-
-    loop {
-        // dive deeper into the stack, recording the path
-        'diving_in: loop {
-            if let Some((inner_most_trait_ref, _, _)) = stack.last() {
-                let inner_most_trait_ref = *inner_most_trait_ref;
-                let mut direct_super_traits_iter = tcx
-                    .super_predicates_of(inner_most_trait_ref.def_id())
-                    .predicates
-                    .into_iter()
-                    .filter_map(move |(pred, _)| {
-                        pred.subst_supertrait(tcx, &inner_most_trait_ref).to_opt_poly_trait_pred()
-                    });
-
-                'diving_in_skip_visited_traits: loop {
-                    if let Some(next_super_trait) = direct_super_traits_iter.next() {
-                        if visited.insert(next_super_trait.to_predicate(tcx)) {
-                            // We're throwing away potential constness of super traits here.
-                            // FIXME: handle ~const super traits
-                            let next_super_trait = next_super_trait.map_bound(|t| t.trait_ref);
-                            stack.push((
-                                next_super_trait,
-                                emit_vptr_on_new_entry,
-                                Some(direct_super_traits_iter),
-                            ));
-                            break 'diving_in_skip_visited_traits;
-                        } else {
-                            continue 'diving_in_skip_visited_traits;
-                        }
-                    } else {
-                        break 'diving_in;
-                    }
-                }
-            }
-        }
-
-        // Other than the left-most path, vptr should be emitted for each trait.
-        emit_vptr_on_new_entry = true;
-
-        // emit innermost item, move to next sibling and stop there if possible, otherwise jump to outer level.
-        'exiting_out: loop {
-            if let Some((inner_most_trait_ref, emit_vptr, siblings_opt)) = stack.last_mut() {
-                if let ControlFlow::Break(v) = (segment_visitor)(VtblSegment::TraitOwnEntries {
-                    trait_ref: *inner_most_trait_ref,
-                    emit_vptr: *emit_vptr,
-                }) {
-                    return Some(v);
-                }
-
-                'exiting_out_skip_visited_traits: loop {
-                    if let Some(siblings) = siblings_opt {
-                        if let Some(next_inner_most_trait_ref) = siblings.next() {
-                            if visited.insert(next_inner_most_trait_ref.to_predicate(tcx)) {
-                                // We're throwing away potential constness of super traits here.
-                                // FIXME: handle ~const super traits
-                                let next_inner_most_trait_ref =
-                                    next_inner_most_trait_ref.map_bound(|t| t.trait_ref);
-                                *inner_most_trait_ref = next_inner_most_trait_ref;
-                                *emit_vptr = emit_vptr_on_new_entry;
-                                break 'exiting_out;
-                            } else {
-                                continue 'exiting_out_skip_visited_traits;
-                            }
-                        }
-                    }
-                    stack.pop();
-                    continue 'exiting_out;
-                }
-            }
-            // all done
-            return None;
-        }
-    }
-}
-
-fn dump_vtable_entries<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    sp: Span,
-    trait_ref: ty::PolyTraitRef<'tcx>,
-    entries: &[VtblEntry<'tcx>],
-) {
-    tcx.sess.emit_err(DumpVTableEntries {
-        span: sp,
-        trait_ref,
-        entries: format!("{:#?}", entries),
-    });
-}
-
-fn own_existential_vtable_entries<'tcx>(tcx: TyCtxt<'tcx>, trait_def_id: DefId) -> &'tcx [DefId] {
-    let trait_methods = tcx
-        .associated_items(trait_def_id)
-        .in_definition_order()
-        .filter(|item| item.kind == ty::AssocKind::Fn);
-    // Now list each method's DefId (for within its trait).
-    let own_entries = trait_methods.filter_map(move |trait_method| {
-        debug!("own_existential_vtable_entry: trait_method={:?}", trait_method);
-        let def_id = trait_method.def_id;
-
-        // Some methods cannot be called on an object; skip those.
-        if !is_vtable_safe_method(tcx, trait_def_id, &trait_method) {
-            debug!("own_existential_vtable_entry: not vtable safe");
-            return None;
-        }
-
-        Some(def_id)
-    });
-
-    tcx.arena.alloc_from_iter(own_entries.into_iter())
-}
-
-/// Given a trait `trait_ref`, iterates the vtable entries
-/// that come from `trait_ref`, including its supertraits.
-fn vtable_entries<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    trait_ref: ty::PolyTraitRef<'tcx>,
-) -> &'tcx [VtblEntry<'tcx>] {
-    debug!("vtable_entries({:?})", trait_ref);
-
-    let mut entries = vec![];
-
-    let vtable_segment_callback = |segment| -> ControlFlow<()> {
-        match segment {
-            VtblSegment::MetadataDSA => {
-                entries.extend(TyCtxt::COMMON_VTABLE_ENTRIES);
-            }
-            VtblSegment::TraitOwnEntries { trait_ref, emit_vptr } => {
-                let existential_trait_ref = trait_ref
-                    .map_bound(|trait_ref| ty::ExistentialTraitRef::erase_self_ty(tcx, trait_ref));
-
-                // Lookup the shape of vtable for the trait.
-                let own_existential_entries =
-                    tcx.own_existential_vtable_entries(existential_trait_ref.def_id());
-
-                let own_entries = own_existential_entries.iter().copied().map(|def_id| {
-                    debug!("vtable_entries: trait_method={:?}", def_id);
-
-                    // The method may have some early-bound lifetimes; add regions for those.
-                    let substs = trait_ref.map_bound(|trait_ref| {
-                        InternalSubsts::for_item(tcx, def_id, |param, _| match param.kind {
-                            GenericParamDefKind::Lifetime => tcx.lifetimes.re_erased.into(),
-                            GenericParamDefKind::Type { .. }
-                            | GenericParamDefKind::Const { .. } => {
-                                trait_ref.substs[param.index as usize]
-                            }
-                        })
-                    });
-
-                    // The trait type may have higher-ranked lifetimes in it;
-                    // erase them if they appear, so that we get the type
-                    // at some particular call site.
-                    let substs = tcx
-                        .normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), substs);
-
-                    // It's possible that the method relies on where-clauses that
-                    // do not hold for this particular set of type parameters.
-                    // Note that this method could then never be called, so we
-                    // do not want to try and codegen it, in that case (see #23435).
-                    let predicates = tcx.predicates_of(def_id).instantiate_own(tcx, substs);
-                    if impossible_predicates(tcx, predicates.predicates) {
-                        debug!("vtable_entries: predicates do not hold");
-                        return VtblEntry::Vacant;
-                    }
-
-                    let instance = ty::Instance::resolve_for_vtable(
-                        tcx,
-                        ty::ParamEnv::reveal_all(),
-                        def_id,
-                        substs,
-                    )
-                    .expect("resolution failed during building vtable representation");
-                    VtblEntry::Method(instance)
-                });
-
-                entries.extend(own_entries);
-
-                if emit_vptr {
-                    entries.push(VtblEntry::TraitVPtr(trait_ref));
-                }
-            }
-        }
-
-        ControlFlow::Continue(())
-    };
-
-    let _ = prepare_vtable_segments(tcx, trait_ref, vtable_segment_callback);
-
-    if tcx.has_attr(trait_ref.def_id(), sym::rustc_dump_vtable) {
-        let sp = tcx.def_span(trait_ref.def_id());
-        dump_vtable_entries(tcx, sp, trait_ref, &entries);
-    }
-
-    tcx.arena.alloc_from_iter(entries.into_iter())
-}
-
-/// Find slot base for trait methods within vtable entries of another trait
-fn vtable_trait_first_method_offset<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    key: (
-        ty::PolyTraitRef<'tcx>, // trait_to_be_found
-        ty::PolyTraitRef<'tcx>, // trait_owning_vtable
-    ),
-) -> usize {
-    let (trait_to_be_found, trait_owning_vtable) = key;
-
-    // #90177
-    let trait_to_be_found_erased = tcx.erase_regions(trait_to_be_found);
-
-    let vtable_segment_callback = {
-        let mut vtable_base = 0;
-
-        move |segment| {
-            match segment {
-                VtblSegment::MetadataDSA => {
-                    vtable_base += TyCtxt::COMMON_VTABLE_ENTRIES.len();
-                }
-                VtblSegment::TraitOwnEntries { trait_ref, emit_vptr } => {
-                    if tcx.erase_regions(trait_ref) == trait_to_be_found_erased {
-                        return ControlFlow::Break(vtable_base);
-                    }
-                    vtable_base += util::count_own_vtable_entries(tcx, trait_ref);
-                    if emit_vptr {
-                        vtable_base += 1;
-                    }
-                }
-            }
-            ControlFlow::Continue(())
-        }
-    };
-
-    if let Some(vtable_base) =
-        prepare_vtable_segments(tcx, trait_owning_vtable, vtable_segment_callback)
-    {
-        vtable_base
-    } else {
-        bug!("Failed to find info for expected trait in vtable");
-    }
-}
-
-/// Find slot offset for trait vptr within vtable entries of another trait
-pub fn vtable_trait_upcasting_coercion_new_vptr_slot<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    key: (
-        Ty<'tcx>, // trait object type whose trait owning vtable
-        Ty<'tcx>, // trait object for supertrait
-    ),
-) -> Option<usize> {
-    let (source, target) = key;
-    assert!(matches!(&source.kind(), &ty::Dynamic(..)) && !source.needs_infer());
-    assert!(matches!(&target.kind(), &ty::Dynamic(..)) && !target.needs_infer());
-
-    // this has been typecked-before, so diagnostics is not really needed.
-    let unsize_trait_did = tcx.require_lang_item(LangItem::Unsize, None);
-
-    let trait_ref = tcx.mk_trait_ref(unsize_trait_did, [source, target]);
-
-    match tcx.codegen_select_candidate((ty::ParamEnv::reveal_all(), ty::Binder::dummy(trait_ref))) {
-        Ok(ImplSource::TraitUpcasting(implsrc_traitcasting)) => {
-            implsrc_traitcasting.vtable_vptr_slot
-        }
-        otherwise => bug!("expected TraitUpcasting candidate, got {otherwise:?}"),
-    }
-}
-
 pub fn provide(providers: &mut ty::query::Providers) {
     object_safety::provide(providers);
-    structural_match::provide(providers);
+    vtable::provide(providers);
     *providers = ty::query::Providers {
         specialization_graph_of: specialize::specialization_graph_provider,
         specializes: specialize::specializes,
-        codegen_select_candidate: codegen::codegen_select_candidate,
-        own_existential_vtable_entries,
-        vtable_entries,
-        vtable_trait_upcasting_coercion_new_vptr_slot,
         subst_and_check_impossible_predicates,
         is_impossible_method,
         ..*providers
diff --git a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
index 22cd700dcb5..fda415155c4 100644
--- a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
@@ -19,6 +19,10 @@ use rustc_span::def_id::DefId;
 
 use crate::traits::project::{normalize_with_depth, normalize_with_depth_to};
 use crate::traits::util::{self, closure_trait_ref_and_return_type, predicate_for_trait_def};
+use crate::traits::vtable::{
+    count_own_vtable_entries, prepare_vtable_segments, vtable_trait_first_method_offset,
+    VtblSegment,
+};
 use crate::traits::{
     BuiltinDerivedObligation, ImplDerivedObligation, ImplDerivedObligationCause, ImplSource,
     ImplSourceAutoImplData, ImplSourceBuiltinData, ImplSourceClosureData,
@@ -26,7 +30,7 @@ use crate::traits::{
     ImplSourceGeneratorData, ImplSourceObjectData, ImplSourceTraitAliasData,
     ImplSourceTraitUpcastingData, ImplSourceUserDefinedData, Normalized, ObjectCastObligation,
     Obligation, ObligationCause, OutputTypeParameterMismatch, PredicateObligation, Selection,
-    SelectionError, TraitNotObjectSafe, TraitObligation, Unimplemented, VtblSegment,
+    SelectionError, TraitNotObjectSafe, TraitObligation, Unimplemented,
 };
 
 use super::BuiltinImplConditions;
@@ -583,7 +587,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
 
         debug!(?nested, "object nested obligations");
 
-        let vtable_base = super::super::vtable_trait_first_method_offset(
+        let vtable_base = vtable_trait_first_method_offset(
             tcx,
             (unnormalized_upcast_trait_ref, ty::Binder::dummy(object_trait_ref)),
         );
@@ -904,7 +908,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                         vptr_offset += TyCtxt::COMMON_VTABLE_ENTRIES.len();
                     }
                     VtblSegment::TraitOwnEntries { trait_ref, emit_vptr } => {
-                        vptr_offset += util::count_own_vtable_entries(tcx, trait_ref);
+                        vptr_offset += count_own_vtable_entries(tcx, trait_ref);
                         if trait_ref == upcast_trait_ref {
                             if emit_vptr {
                                 return ControlFlow::Break(Some(vptr_offset));
@@ -923,8 +927,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         };
 
         let vtable_vptr_slot =
-            super::super::prepare_vtable_segments(tcx, source_trait_ref, vtable_segment_callback)
-                .unwrap();
+            prepare_vtable_segments(tcx, source_trait_ref, vtable_segment_callback).unwrap();
 
         Ok(ImplSourceTraitUpcastingData { upcast_trait_ref, vtable_vptr_slot, nested })
     }
diff --git a/compiler/rustc_trait_selection/src/traits/structural_match.rs b/compiler/rustc_trait_selection/src/traits/structural_match.rs
index 40dbe0b3ff0..4dc08e0f9da 100644
--- a/compiler/rustc_trait_selection/src/traits/structural_match.rs
+++ b/compiler/rustc_trait_selection/src/traits/structural_match.rs
@@ -1,10 +1,5 @@
-use crate::infer::{InferCtxt, TyCtxtInferExt};
-use crate::traits::{ObligationCause, ObligationCtxt};
-
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir as hir;
-use rustc_hir::lang_items::LangItem;
-use rustc_middle::ty::query::Providers;
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitor};
 use rustc_span::Span;
 use std::ops::ControlFlow;
@@ -59,41 +54,6 @@ pub fn search_for_adt_const_param_violation<'tcx>(
         .break_value()
 }
 
-/// This method returns true if and only if `adt_ty` itself has been marked as
-/// eligible for structural-match: namely, if it implements both
-/// `StructuralPartialEq` and `StructuralEq` (which are respectively injected by
-/// `#[derive(PartialEq)]` and `#[derive(Eq)]`).
-///
-/// Note that this does *not* recursively check if the substructure of `adt_ty`
-/// implements the traits.
-fn type_marked_structural<'tcx>(
-    infcx: &InferCtxt<'tcx>,
-    adt_ty: Ty<'tcx>,
-    cause: ObligationCause<'tcx>,
-) -> bool {
-    let ocx = ObligationCtxt::new(infcx);
-    // require `#[derive(PartialEq)]`
-    let structural_peq_def_id =
-        infcx.tcx.require_lang_item(LangItem::StructuralPeq, Some(cause.span));
-    ocx.register_bound(cause.clone(), ty::ParamEnv::empty(), adt_ty, structural_peq_def_id);
-    // for now, require `#[derive(Eq)]`. (Doing so is a hack to work around
-    // the type `for<'a> fn(&'a ())` failing to implement `Eq` itself.)
-    let structural_teq_def_id =
-        infcx.tcx.require_lang_item(LangItem::StructuralTeq, Some(cause.span));
-    ocx.register_bound(cause, ty::ParamEnv::empty(), adt_ty, structural_teq_def_id);
-
-    // We deliberately skip *reporting* fulfillment errors (via
-    // `report_fulfillment_errors`), for two reasons:
-    //
-    // 1. The error messages would mention `std::marker::StructuralPartialEq`
-    //    (a trait which is solely meant as an implementation detail
-    //    for now), and
-    //
-    // 2. We are sometimes doing future-incompatibility lints for
-    //    now, so we do not want unconditional errors here.
-    ocx.select_all_or_error().is_empty()
-}
-
 /// This implements the traversal over the structure of a given type to try to
 /// find instances of ADTs (specifically structs or enums) that do not implement
 /// the structural-match traits (`StructuralPartialEq` and `StructuralEq`).
@@ -249,11 +209,3 @@ impl<'tcx> TypeVisitor<'tcx> for Search<'tcx> {
         })
     }
 }
-
-pub fn provide(providers: &mut Providers) {
-    providers.has_structural_eq_impls = |tcx, ty| {
-        let infcx = tcx.infer_ctxt().build();
-        let cause = ObligationCause::dummy();
-        type_marked_structural(&infcx, ty, cause)
-    };
-}
diff --git a/compiler/rustc_trait_selection/src/traits/util.rs b/compiler/rustc_trait_selection/src/traits/util.rs
index 51968c2d7a1..f3ca6a6c779 100644
--- a/compiler/rustc_trait_selection/src/traits/util.rs
+++ b/compiler/rustc_trait_selection/src/traits/util.rs
@@ -261,16 +261,6 @@ pub fn upcast_choices<'tcx>(
     supertraits(tcx, source_trait_ref).filter(|r| r.def_id() == target_trait_def_id).collect()
 }
 
-/// Given a trait `trait_ref`, returns the number of vtable entries
-/// that come from `trait_ref`, excluding its supertraits. Used in
-/// computing the vtable base for an upcast trait of a trait object.
-pub fn count_own_vtable_entries<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    trait_ref: ty::PolyTraitRef<'tcx>,
-) -> usize {
-    tcx.own_existential_vtable_entries(trait_ref.def_id()).len()
-}
-
 /// Given an upcast trait object described by `object`, returns the
 /// index of the method `method_def_id` (which should be part of
 /// `object.upcast_trait_ref`) within the vtable for `object`.
diff --git a/compiler/rustc_trait_selection/src/traits/vtable.rs b/compiler/rustc_trait_selection/src/traits/vtable.rs
new file mode 100644
index 00000000000..41ce6cdf789
--- /dev/null
+++ b/compiler/rustc_trait_selection/src/traits/vtable.rs
@@ -0,0 +1,386 @@
+use crate::errors::DumpVTableEntries;
+use crate::traits::{impossible_predicates, is_vtable_safe_method};
+use rustc_hir::def_id::DefId;
+use rustc_hir::lang_items::LangItem;
+use rustc_infer::traits::util::PredicateSet;
+use rustc_infer::traits::ImplSource;
+use rustc_middle::ty::visit::TypeVisitable;
+use rustc_middle::ty::InternalSubsts;
+use rustc_middle::ty::{self, GenericParamDefKind, ToPredicate, Ty, TyCtxt, VtblEntry};
+use rustc_span::{sym, Span};
+use smallvec::SmallVec;
+
+use std::fmt::Debug;
+use std::ops::ControlFlow;
+
+#[derive(Clone, Debug)]
+pub(super) enum VtblSegment<'tcx> {
+    MetadataDSA,
+    TraitOwnEntries { trait_ref: ty::PolyTraitRef<'tcx>, emit_vptr: bool },
+}
+
+/// Prepare the segments for a vtable
+pub(super) fn prepare_vtable_segments<'tcx, T>(
+    tcx: TyCtxt<'tcx>,
+    trait_ref: ty::PolyTraitRef<'tcx>,
+    mut segment_visitor: impl FnMut(VtblSegment<'tcx>) -> ControlFlow<T>,
+) -> Option<T> {
+    // The following constraints holds for the final arrangement.
+    // 1. The whole virtual table of the first direct super trait is included as the
+    //    the prefix. If this trait doesn't have any super traits, then this step
+    //    consists of the dsa metadata.
+    // 2. Then comes the proper pointer metadata(vptr) and all own methods for all
+    //    other super traits except those already included as part of the first
+    //    direct super trait virtual table.
+    // 3. finally, the own methods of this trait.
+
+    // This has the advantage that trait upcasting to the first direct super trait on each level
+    // is zero cost, and to another trait includes only replacing the pointer with one level indirection,
+    // while not using too much extra memory.
+
+    // For a single inheritance relationship like this,
+    //   D --> C --> B --> A
+    // The resulting vtable will consists of these segments:
+    //  DSA, A, B, C, D
+
+    // For a multiple inheritance relationship like this,
+    //   D --> C --> A
+    //           \-> B
+    // The resulting vtable will consists of these segments:
+    //  DSA, A, B, B-vptr, C, D
+
+    // For a diamond inheritance relationship like this,
+    //   D --> B --> A
+    //     \-> C -/
+    // The resulting vtable will consists of these segments:
+    //  DSA, A, B, C, C-vptr, D
+
+    // For a more complex inheritance relationship like this:
+    //   O --> G --> C --> A
+    //     \     \     \-> B
+    //     |     |-> F --> D
+    //     |           \-> E
+    //     |-> N --> J --> H
+    //           \     \-> I
+    //           |-> M --> K
+    //                 \-> L
+    // The resulting vtable will consists of these segments:
+    //  DSA, A, B, B-vptr, C, D, D-vptr, E, E-vptr, F, F-vptr, G,
+    //  H, H-vptr, I, I-vptr, J, J-vptr, K, K-vptr, L, L-vptr, M, M-vptr,
+    //  N, N-vptr, O
+
+    // emit dsa segment first.
+    if let ControlFlow::Break(v) = (segment_visitor)(VtblSegment::MetadataDSA) {
+        return Some(v);
+    }
+
+    let mut emit_vptr_on_new_entry = false;
+    let mut visited = PredicateSet::new(tcx);
+    let predicate = trait_ref.without_const().to_predicate(tcx);
+    let mut stack: SmallVec<[(ty::PolyTraitRef<'tcx>, _, _); 5]> =
+        smallvec![(trait_ref, emit_vptr_on_new_entry, None)];
+    visited.insert(predicate);
+
+    // the main traversal loop:
+    // basically we want to cut the inheritance directed graph into a few non-overlapping slices of nodes
+    // that each node is emitted after all its descendents have been emitted.
+    // so we convert the directed graph into a tree by skipping all previously visited nodes using a visited set.
+    // this is done on the fly.
+    // Each loop run emits a slice - it starts by find a "childless" unvisited node, backtracking upwards, and it
+    // stops after it finds a node that has a next-sibling node.
+    // This next-sibling node will used as the starting point of next slice.
+
+    // Example:
+    // For a diamond inheritance relationship like this,
+    //   D#1 --> B#0 --> A#0
+    //     \-> C#1 -/
+
+    // Starting point 0 stack [D]
+    // Loop run #0: Stack after diving in is [D B A], A is "childless"
+    // after this point, all newly visited nodes won't have a vtable that equals to a prefix of this one.
+    // Loop run #0: Emitting the slice [B A] (in reverse order), B has a next-sibling node, so this slice stops here.
+    // Loop run #0: Stack after exiting out is [D C], C is the next starting point.
+    // Loop run #1: Stack after diving in is [D C], C is "childless", since its child A is skipped(already emitted).
+    // Loop run #1: Emitting the slice [D C] (in reverse order). No one has a next-sibling node.
+    // Loop run #1: Stack after exiting out is []. Now the function exits.
+
+    loop {
+        // dive deeper into the stack, recording the path
+        'diving_in: loop {
+            if let Some((inner_most_trait_ref, _, _)) = stack.last() {
+                let inner_most_trait_ref = *inner_most_trait_ref;
+                let mut direct_super_traits_iter = tcx
+                    .super_predicates_of(inner_most_trait_ref.def_id())
+                    .predicates
+                    .into_iter()
+                    .filter_map(move |(pred, _)| {
+                        pred.subst_supertrait(tcx, &inner_most_trait_ref).to_opt_poly_trait_pred()
+                    });
+
+                'diving_in_skip_visited_traits: loop {
+                    if let Some(next_super_trait) = direct_super_traits_iter.next() {
+                        if visited.insert(next_super_trait.to_predicate(tcx)) {
+                            // We're throwing away potential constness of super traits here.
+                            // FIXME: handle ~const super traits
+                            let next_super_trait = next_super_trait.map_bound(|t| t.trait_ref);
+                            stack.push((
+                                next_super_trait,
+                                emit_vptr_on_new_entry,
+                                Some(direct_super_traits_iter),
+                            ));
+                            break 'diving_in_skip_visited_traits;
+                        } else {
+                            continue 'diving_in_skip_visited_traits;
+                        }
+                    } else {
+                        break 'diving_in;
+                    }
+                }
+            }
+        }
+
+        // Other than the left-most path, vptr should be emitted for each trait.
+        emit_vptr_on_new_entry = true;
+
+        // emit innermost item, move to next sibling and stop there if possible, otherwise jump to outer level.
+        'exiting_out: loop {
+            if let Some((inner_most_trait_ref, emit_vptr, siblings_opt)) = stack.last_mut() {
+                if let ControlFlow::Break(v) = (segment_visitor)(VtblSegment::TraitOwnEntries {
+                    trait_ref: *inner_most_trait_ref,
+                    emit_vptr: *emit_vptr,
+                }) {
+                    return Some(v);
+                }
+
+                'exiting_out_skip_visited_traits: loop {
+                    if let Some(siblings) = siblings_opt {
+                        if let Some(next_inner_most_trait_ref) = siblings.next() {
+                            if visited.insert(next_inner_most_trait_ref.to_predicate(tcx)) {
+                                // We're throwing away potential constness of super traits here.
+                                // FIXME: handle ~const super traits
+                                let next_inner_most_trait_ref =
+                                    next_inner_most_trait_ref.map_bound(|t| t.trait_ref);
+                                *inner_most_trait_ref = next_inner_most_trait_ref;
+                                *emit_vptr = emit_vptr_on_new_entry;
+                                break 'exiting_out;
+                            } else {
+                                continue 'exiting_out_skip_visited_traits;
+                            }
+                        }
+                    }
+                    stack.pop();
+                    continue 'exiting_out;
+                }
+            }
+            // all done
+            return None;
+        }
+    }
+}
+
+fn dump_vtable_entries<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    sp: Span,
+    trait_ref: ty::PolyTraitRef<'tcx>,
+    entries: &[VtblEntry<'tcx>],
+) {
+    tcx.sess.emit_err(DumpVTableEntries {
+        span: sp,
+        trait_ref,
+        entries: format!("{:#?}", entries),
+    });
+}
+
+fn own_existential_vtable_entries<'tcx>(tcx: TyCtxt<'tcx>, trait_def_id: DefId) -> &'tcx [DefId] {
+    let trait_methods = tcx
+        .associated_items(trait_def_id)
+        .in_definition_order()
+        .filter(|item| item.kind == ty::AssocKind::Fn);
+    // Now list each method's DefId (for within its trait).
+    let own_entries = trait_methods.filter_map(move |trait_method| {
+        debug!("own_existential_vtable_entry: trait_method={:?}", trait_method);
+        let def_id = trait_method.def_id;
+
+        // Some methods cannot be called on an object; skip those.
+        if !is_vtable_safe_method(tcx, trait_def_id, &trait_method) {
+            debug!("own_existential_vtable_entry: not vtable safe");
+            return None;
+        }
+
+        Some(def_id)
+    });
+
+    tcx.arena.alloc_from_iter(own_entries.into_iter())
+}
+
+/// Given a trait `trait_ref`, iterates the vtable entries
+/// that come from `trait_ref`, including its supertraits.
+fn vtable_entries<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    trait_ref: ty::PolyTraitRef<'tcx>,
+) -> &'tcx [VtblEntry<'tcx>] {
+    debug!("vtable_entries({:?})", trait_ref);
+
+    let mut entries = vec![];
+
+    let vtable_segment_callback = |segment| -> ControlFlow<()> {
+        match segment {
+            VtblSegment::MetadataDSA => {
+                entries.extend(TyCtxt::COMMON_VTABLE_ENTRIES);
+            }
+            VtblSegment::TraitOwnEntries { trait_ref, emit_vptr } => {
+                let existential_trait_ref = trait_ref
+                    .map_bound(|trait_ref| ty::ExistentialTraitRef::erase_self_ty(tcx, trait_ref));
+
+                // Lookup the shape of vtable for the trait.
+                let own_existential_entries =
+                    tcx.own_existential_vtable_entries(existential_trait_ref.def_id());
+
+                let own_entries = own_existential_entries.iter().copied().map(|def_id| {
+                    debug!("vtable_entries: trait_method={:?}", def_id);
+
+                    // The method may have some early-bound lifetimes; add regions for those.
+                    let substs = trait_ref.map_bound(|trait_ref| {
+                        InternalSubsts::for_item(tcx, def_id, |param, _| match param.kind {
+                            GenericParamDefKind::Lifetime => tcx.lifetimes.re_erased.into(),
+                            GenericParamDefKind::Type { .. }
+                            | GenericParamDefKind::Const { .. } => {
+                                trait_ref.substs[param.index as usize]
+                            }
+                        })
+                    });
+
+                    // The trait type may have higher-ranked lifetimes in it;
+                    // erase them if they appear, so that we get the type
+                    // at some particular call site.
+                    let substs = tcx
+                        .normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), substs);
+
+                    // It's possible that the method relies on where-clauses that
+                    // do not hold for this particular set of type parameters.
+                    // Note that this method could then never be called, so we
+                    // do not want to try and codegen it, in that case (see #23435).
+                    let predicates = tcx.predicates_of(def_id).instantiate_own(tcx, substs);
+                    if impossible_predicates(tcx, predicates.predicates) {
+                        debug!("vtable_entries: predicates do not hold");
+                        return VtblEntry::Vacant;
+                    }
+
+                    let instance = ty::Instance::resolve_for_vtable(
+                        tcx,
+                        ty::ParamEnv::reveal_all(),
+                        def_id,
+                        substs,
+                    )
+                    .expect("resolution failed during building vtable representation");
+                    VtblEntry::Method(instance)
+                });
+
+                entries.extend(own_entries);
+
+                if emit_vptr {
+                    entries.push(VtblEntry::TraitVPtr(trait_ref));
+                }
+            }
+        }
+
+        ControlFlow::Continue(())
+    };
+
+    let _ = prepare_vtable_segments(tcx, trait_ref, vtable_segment_callback);
+
+    if tcx.has_attr(trait_ref.def_id(), sym::rustc_dump_vtable) {
+        let sp = tcx.def_span(trait_ref.def_id());
+        dump_vtable_entries(tcx, sp, trait_ref, &entries);
+    }
+
+    tcx.arena.alloc_from_iter(entries.into_iter())
+}
+
+/// Find slot base for trait methods within vtable entries of another trait
+pub(super) fn vtable_trait_first_method_offset<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    key: (
+        ty::PolyTraitRef<'tcx>, // trait_to_be_found
+        ty::PolyTraitRef<'tcx>, // trait_owning_vtable
+    ),
+) -> usize {
+    let (trait_to_be_found, trait_owning_vtable) = key;
+
+    // #90177
+    let trait_to_be_found_erased = tcx.erase_regions(trait_to_be_found);
+
+    let vtable_segment_callback = {
+        let mut vtable_base = 0;
+
+        move |segment| {
+            match segment {
+                VtblSegment::MetadataDSA => {
+                    vtable_base += TyCtxt::COMMON_VTABLE_ENTRIES.len();
+                }
+                VtblSegment::TraitOwnEntries { trait_ref, emit_vptr } => {
+                    if tcx.erase_regions(trait_ref) == trait_to_be_found_erased {
+                        return ControlFlow::Break(vtable_base);
+                    }
+                    vtable_base += count_own_vtable_entries(tcx, trait_ref);
+                    if emit_vptr {
+                        vtable_base += 1;
+                    }
+                }
+            }
+            ControlFlow::Continue(())
+        }
+    };
+
+    if let Some(vtable_base) =
+        prepare_vtable_segments(tcx, trait_owning_vtable, vtable_segment_callback)
+    {
+        vtable_base
+    } else {
+        bug!("Failed to find info for expected trait in vtable");
+    }
+}
+
+/// Find slot offset for trait vptr within vtable entries of another trait
+pub(crate) fn vtable_trait_upcasting_coercion_new_vptr_slot<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    key: (
+        Ty<'tcx>, // trait object type whose trait owning vtable
+        Ty<'tcx>, // trait object for supertrait
+    ),
+) -> Option<usize> {
+    let (source, target) = key;
+    assert!(matches!(&source.kind(), &ty::Dynamic(..)) && !source.needs_infer());
+    assert!(matches!(&target.kind(), &ty::Dynamic(..)) && !target.needs_infer());
+
+    // this has been typecked-before, so diagnostics is not really needed.
+    let unsize_trait_did = tcx.require_lang_item(LangItem::Unsize, None);
+
+    let trait_ref = tcx.mk_trait_ref(unsize_trait_did, [source, target]);
+
+    match tcx.codegen_select_candidate((ty::ParamEnv::reveal_all(), ty::Binder::dummy(trait_ref))) {
+        Ok(ImplSource::TraitUpcasting(implsrc_traitcasting)) => {
+            implsrc_traitcasting.vtable_vptr_slot
+        }
+        otherwise => bug!("expected TraitUpcasting candidate, got {otherwise:?}"),
+    }
+}
+
+/// Given a trait `trait_ref`, returns the number of vtable entries
+/// that come from `trait_ref`, excluding its supertraits. Used in
+/// computing the vtable base for an upcast trait of a trait object.
+pub(crate) fn count_own_vtable_entries<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    trait_ref: ty::PolyTraitRef<'tcx>,
+) -> usize {
+    tcx.own_existential_vtable_entries(trait_ref.def_id()).len()
+}
+
+pub(super) fn provide(providers: &mut ty::query::Providers) {
+    *providers = ty::query::Providers {
+        own_existential_vtable_entries,
+        vtable_entries,
+        vtable_trait_upcasting_coercion_new_vptr_slot,
+        ..*providers
+    };
+}
diff --git a/compiler/rustc_trait_selection/src/traits/codegen.rs b/compiler/rustc_traits/src/codegen.rs
index 0102d268b42..f8f74b732ef 100644
--- a/compiler/rustc_trait_selection/src/traits/codegen.rs
+++ b/compiler/rustc_traits/src/codegen.rs
@@ -3,15 +3,15 @@
 // seems likely that they should eventually be merged into more
 // general routines.
 
-use crate::infer::{DefiningAnchor, TyCtxtInferExt};
-use crate::traits::error_reporting::TypeErrCtxtExt;
-use crate::traits::{
-    ImplSource, Obligation, ObligationCause, SelectionContext, TraitEngine, TraitEngineExt,
-    Unimplemented,
-};
+use rustc_infer::infer::{DefiningAnchor, TyCtxtInferExt};
 use rustc_infer::traits::FulfillmentErrorCode;
 use rustc_middle::traits::CodegenObligationError;
 use rustc_middle::ty::{self, TyCtxt};
+use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
+use rustc_trait_selection::traits::{
+    ImplSource, Obligation, ObligationCause, SelectionContext, TraitEngine, TraitEngineExt,
+    Unimplemented,
+};
 
 /// Attempts to resolve an obligation to an `ImplSource`. The result is
 /// a shallow `ImplSource` resolution, meaning that we do not
diff --git a/compiler/rustc_traits/src/lib.rs b/compiler/rustc_traits/src/lib.rs
index 0ffa92f1ad5..9aa26667e7b 100644
--- a/compiler/rustc_traits/src/lib.rs
+++ b/compiler/rustc_traits/src/lib.rs
@@ -12,6 +12,7 @@ extern crate tracing;
 extern crate rustc_middle;
 
 mod chalk;
+mod codegen;
 mod dropck_outlives;
 mod evaluate_obligation;
 mod implied_outlives_bounds;
@@ -31,4 +32,5 @@ pub fn provide(p: &mut Providers) {
     normalize_projection_ty::provide(p);
     normalize_erasing_regions::provide(p);
     type_op::provide(p);
+    p.codegen_select_candidate = codegen::codegen_select_candidate;
 }
diff --git a/compiler/rustc_ty_utils/src/lib.rs b/compiler/rustc_ty_utils/src/lib.rs
index cce5a79ddc8..7ad5cbc01cc 100644
--- a/compiler/rustc_ty_utils/src/lib.rs
+++ b/compiler/rustc_ty_utils/src/lib.rs
@@ -29,6 +29,7 @@ mod layout;
 mod layout_sanity_check;
 mod needs_drop;
 pub mod representability;
+mod structural_match;
 mod ty;
 
 pub fn provide(providers: &mut Providers) {
@@ -42,4 +43,5 @@ pub fn provide(providers: &mut Providers) {
     representability::provide(providers);
     ty::provide(providers);
     instance::provide(providers);
+    structural_match::provide(providers);
 }
diff --git a/compiler/rustc_ty_utils/src/structural_match.rs b/compiler/rustc_ty_utils/src/structural_match.rs
new file mode 100644
index 00000000000..a55bb7e7e90
--- /dev/null
+++ b/compiler/rustc_ty_utils/src/structural_match.rs
@@ -0,0 +1,44 @@
+use rustc_hir::lang_items::LangItem;
+use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::{self, Ty, TyCtxt};
+
+use rustc_infer::infer::TyCtxtInferExt;
+use rustc_trait_selection::traits::{ObligationCause, ObligationCtxt};
+
+/// This method returns true if and only if `adt_ty` itself has been marked as
+/// eligible for structural-match: namely, if it implements both
+/// `StructuralPartialEq` and `StructuralEq` (which are respectively injected by
+/// `#[derive(PartialEq)]` and `#[derive(Eq)]`).
+///
+/// Note that this does *not* recursively check if the substructure of `adt_ty`
+/// implements the traits.
+fn has_structural_eq_impls<'tcx>(tcx: TyCtxt<'tcx>, adt_ty: Ty<'tcx>) -> bool {
+    let ref infcx = tcx.infer_ctxt().build();
+    let cause = ObligationCause::dummy();
+
+    let ocx = ObligationCtxt::new(infcx);
+    // require `#[derive(PartialEq)]`
+    let structural_peq_def_id =
+        infcx.tcx.require_lang_item(LangItem::StructuralPeq, Some(cause.span));
+    ocx.register_bound(cause.clone(), ty::ParamEnv::empty(), adt_ty, structural_peq_def_id);
+    // for now, require `#[derive(Eq)]`. (Doing so is a hack to work around
+    // the type `for<'a> fn(&'a ())` failing to implement `Eq` itself.)
+    let structural_teq_def_id =
+        infcx.tcx.require_lang_item(LangItem::StructuralTeq, Some(cause.span));
+    ocx.register_bound(cause, ty::ParamEnv::empty(), adt_ty, structural_teq_def_id);
+
+    // We deliberately skip *reporting* fulfillment errors (via
+    // `report_fulfillment_errors`), for two reasons:
+    //
+    // 1. The error messages would mention `std::marker::StructuralPartialEq`
+    //    (a trait which is solely meant as an implementation detail
+    //    for now), and
+    //
+    // 2. We are sometimes doing future-incompatibility lints for
+    //    now, so we do not want unconditional errors here.
+    ocx.select_all_or_error().is_empty()
+}
+
+pub fn provide(providers: &mut Providers) {
+    providers.has_structural_eq_impls = has_structural_eq_impls;
+}
diff --git a/library/core/src/num/mod.rs b/library/core/src/num/mod.rs
index b2328b001de..ac7f579ebb5 100644
--- a/library/core/src/num/mod.rs
+++ b/library/core/src/num/mod.rs
@@ -4,12 +4,14 @@
 
 use crate::ascii;
 use crate::convert::TryInto;
-use crate::error::Error;
 use crate::intrinsics;
 use crate::mem;
 use crate::ops::{Add, Mul, Sub};
 use crate::str::FromStr;
 
+#[cfg(not(no_fp_fmt_parse))]
+use crate::error::Error;
+
 // Used because the `?` operator is not allowed in a const context.
 macro_rules! try_opt {
     ($e:expr) => {
diff --git a/library/core/src/slice/mod.rs b/library/core/src/slice/mod.rs
index 04486ed2d14..3d7a7cfaf35 100644
--- a/library/core/src/slice/mod.rs
+++ b/library/core/src/slice/mod.rs
@@ -3468,10 +3468,11 @@ impl<T> [T] {
     /// maintained.
     ///
     /// This method splits the slice into three distinct slices: prefix, correctly aligned middle
-    /// slice of a new type, and the suffix slice. The method may make the middle slice the greatest
-    /// length possible for a given type and input slice, but only your algorithm's performance
-    /// should depend on that, not its correctness. It is permissible for all of the input data to
-    /// be returned as the prefix or suffix slice.
+    /// slice of a new type, and the suffix slice. How exactly the slice is split up is not
+    /// specified; the middle part may be smaller than necessary. However, if this fails to return a
+    /// maximal middle part, that is because code is running in a context where performance does not
+    /// matter, such as a sanitizer attempting to find alignment bugs. Regular code running
+    /// in a default (debug or release) execution *will* return a maximal middle part.
     ///
     /// This method has no purpose when either input element `T` or output element `U` are
     /// zero-sized and will return the original slice without splitting anything.
@@ -3529,10 +3530,11 @@ impl<T> [T] {
     /// types is maintained.
     ///
     /// This method splits the slice into three distinct slices: prefix, correctly aligned middle
-    /// slice of a new type, and the suffix slice. The method may make the middle slice the greatest
-    /// length possible for a given type and input slice, but only your algorithm's performance
-    /// should depend on that, not its correctness. It is permissible for all of the input data to
-    /// be returned as the prefix or suffix slice.
+    /// slice of a new type, and the suffix slice. How exactly the slice is split up is not
+    /// specified; the middle part may be smaller than necessary. However, if this fails to return a
+    /// maximal middle part, that is because code is running in a context where performance does not
+    /// matter, such as a sanitizer attempting to find alignment bugs. Regular code running
+    /// in a default (debug or release) execution *will* return a maximal middle part.
     ///
     /// This method has no purpose when either input element `T` or output element `U` are
     /// zero-sized and will return the original slice without splitting anything.
diff --git a/library/std/src/sys/itron/condvar.rs b/library/std/src/sys/itron/condvar.rs
index f70aa434e48..7a47cc6696a 100644
--- a/library/std/src/sys/itron/condvar.rs
+++ b/library/std/src/sys/itron/condvar.rs
@@ -71,7 +71,7 @@ impl Condvar {
             }
         }
 
-        unsafe { mutex.lock() };
+        mutex.lock();
     }
 
     pub unsafe fn wait_timeout(&self, mutex: &Mutex, dur: Duration) -> bool {
@@ -109,7 +109,7 @@ impl Condvar {
         // we woke up because of `notify_*`.
         let success = self.waiters.with_locked(|waiters| unsafe { !waiters.remove(waiter) });
 
-        unsafe { mutex.lock() };
+        mutex.lock();
         success
     }
 }
diff --git a/library/std/src/sys/itron/mutex.rs b/library/std/src/sys/itron/mutex.rs
index f2eed8e771c..1f6cc419476 100644
--- a/library/std/src/sys/itron/mutex.rs
+++ b/library/std/src/sys/itron/mutex.rs
@@ -72,7 +72,7 @@ pub(super) struct MutexGuard<'a>(&'a Mutex);
 impl<'a> MutexGuard<'a> {
     #[inline]
     pub(super) fn lock(x: &'a Mutex) -> Self {
-        unsafe { x.lock() };
+        x.lock();
         Self(x)
     }
 }
diff --git a/library/std/src/sys/itron/thread.rs b/library/std/src/sys/itron/thread.rs
index d28f57f33be..c2b36680872 100644
--- a/library/std/src/sys/itron/thread.rs
+++ b/library/std/src/sys/itron/thread.rs
@@ -11,18 +11,25 @@ use crate::{
     ffi::CStr,
     hint, io,
     mem::ManuallyDrop,
+    ptr::NonNull,
     sync::atomic::{AtomicUsize, Ordering},
     sys::thread_local_dtor::run_dtors,
     time::Duration,
 };
 
 pub struct Thread {
-    inner: ManuallyDrop<Box<ThreadInner>>,
+    p_inner: NonNull<ThreadInner>,
 
     /// The ID of the underlying task.
     task: abi::ID,
 }
 
+// Safety: There's nothing in `Thread` that ties it to the original creator. It
+//         can be dropped by any threads.
+unsafe impl Send for Thread {}
+// Safety: `Thread` provides no methods that take `&self`.
+unsafe impl Sync for Thread {}
+
 /// State data shared between a parent thread and child thread. It's dropped on
 /// a transition to one of the final states.
 struct ThreadInner {
@@ -90,8 +97,9 @@ impl Thread {
         });
 
         unsafe extern "C" fn trampoline(exinf: isize) {
+            let p_inner: *mut ThreadInner = crate::ptr::from_exposed_addr_mut(exinf as usize);
             // Safety: `ThreadInner` is alive at this point
-            let inner = unsafe { &*(exinf as *const ThreadInner) };
+            let inner = unsafe { &*p_inner };
 
             // Safety: Since `trampoline` is called only once for each
             //         `ThreadInner` and only `trampoline` touches `start`,
@@ -119,13 +127,13 @@ impl Thread {
                     // No one will ever join, so we'll ask the collector task to
                     // delete the task.
 
-                    // In this case, `inner`'s ownership has been moved to us,
-                    // And we are responsible for dropping it. The acquire
+                    // In this case, `*p_inner`'s ownership has been moved to
+                    // us, and we are responsible for dropping it. The acquire
                     // ordering is not necessary because the parent thread made
                     // no memory access needing synchronization since the call
                     // to `acre_tsk`.
                     // Safety: See above.
-                    let _ = unsafe { Box::from_raw(inner as *const _ as *mut ThreadInner) };
+                    let _ = unsafe { Box::from_raw(p_inner) };
 
                     // Safety: There are no pinned references to the stack
                     unsafe { terminate_and_delete_current_task() };
@@ -162,13 +170,14 @@ impl Thread {
             }
         }
 
-        let inner_ptr = (&*inner) as *const ThreadInner;
+        // Safety: `Box::into_raw` returns a non-null pointer
+        let p_inner = unsafe { NonNull::new_unchecked(Box::into_raw(inner)) };
 
         let new_task = ItronError::err_if_negative(unsafe {
             abi::acre_tsk(&abi::T_CTSK {
                 // Activate this task immediately
                 tskatr: abi::TA_ACT,
-                exinf: inner_ptr as abi::EXINF,
+                exinf: p_inner.as_ptr().expose_addr() as abi::EXINF,
                 // The entry point
                 task: Some(trampoline),
                 // Inherit the calling task's base priority
@@ -180,7 +189,7 @@ impl Thread {
         })
         .map_err(|e| e.as_io_error())?;
 
-        Ok(Self { inner: ManuallyDrop::new(inner), task: new_task })
+        Ok(Self { p_inner, task: new_task })
     }
 
     pub fn yield_now() {
@@ -197,8 +206,9 @@ impl Thread {
         }
     }
 
-    pub fn join(mut self) {
-        let inner = &*self.inner;
+    pub fn join(self) {
+        // Safety: `ThreadInner` is alive at this point
+        let inner = unsafe { self.p_inner.as_ref() };
         // Get the current task ID. Panicking here would cause a resource leak,
         // so just abort on failure.
         let current_task = task::current_task_id_aborting();
@@ -243,8 +253,8 @@ impl Thread {
         unsafe { terminate_and_delete_task(self.task) };
 
         // In either case, we are responsible for dropping `inner`.
-        // Safety: The contents of `self.inner` will not be accessed hereafter
-        let _inner = unsafe { ManuallyDrop::take(&mut self.inner) };
+        // Safety: The contents of `*p_inner` will not be accessed hereafter
+        let _inner = unsafe { Box::from_raw(self.p_inner.as_ptr()) };
 
         // Skip the destructor (because it would attempt to detach the thread)
         crate::mem::forget(self);
@@ -253,13 +263,16 @@ impl Thread {
 
 impl Drop for Thread {
     fn drop(&mut self) {
+        // Safety: `ThreadInner` is alive at this point
+        let inner = unsafe { self.p_inner.as_ref() };
+
         // Detach the thread.
-        match self.inner.lifecycle.swap(LIFECYCLE_DETACHED_OR_JOINED, Ordering::Acquire) {
+        match inner.lifecycle.swap(LIFECYCLE_DETACHED_OR_JOINED, Ordering::Acquire) {
             LIFECYCLE_INIT => {
                 // [INIT → DETACHED]
                 // When the time comes, the child will figure out that no
                 // one will ever join it.
-                // The ownership of `self.inner` is moved to the child thread.
+                // The ownership of `*p_inner` is moved to the child thread.
                 // However, the release ordering is not necessary because we
                 // made no memory access needing synchronization since the call
                 // to `acre_tsk`.
@@ -278,10 +291,9 @@ impl Drop for Thread {
                 //         delete by entering the `FINISHED` state.
                 unsafe { terminate_and_delete_task(self.task) };
 
-                // Wwe are responsible for dropping `inner`.
-                // Safety: The contents of `self.inner` will not be accessed
-                //         hereafter
-                unsafe { ManuallyDrop::drop(&mut self.inner) };
+                // Wwe are responsible for dropping `*p_inner`.
+                // Safety: The contents of `*p_inner` will not be accessed hereafter
+                let _ = unsafe { Box::from_raw(self.p_inner.as_ptr()) };
             }
             _ => unsafe { hint::unreachable_unchecked() },
         }
diff --git a/library/std/src/sys/solid/io.rs b/library/std/src/sys/solid/io.rs
index 9eb17a10daa..a862bb78702 100644
--- a/library/std/src/sys/solid/io.rs
+++ b/library/std/src/sys/solid/io.rs
@@ -75,3 +75,7 @@ impl<'a> IoSliceMut<'a> {
         unsafe { slice::from_raw_parts_mut(self.vec.iov_base as *mut u8, self.vec.iov_len) }
     }
 }
+
+pub fn is_terminal<T>(_: &T) -> bool {
+    false
+}
diff --git a/library/std/src/sys/solid/os.rs b/library/std/src/sys/solid/os.rs
index 4906c62689d..6135921f0b5 100644
--- a/library/std/src/sys/solid/os.rs
+++ b/library/std/src/sys/solid/os.rs
@@ -1,7 +1,6 @@
 use super::unsupported;
-use crate::convert::TryFrom;
 use crate::error::Error as StdError;
-use crate::ffi::{CStr, CString, OsStr, OsString};
+use crate::ffi::{CStr, OsStr, OsString};
 use crate::fmt;
 use crate::io;
 use crate::os::{
diff --git a/src/ci/docker/host-x86_64/dist-powerpc64le-linux/Dockerfile b/src/ci/docker/host-x86_64/dist-powerpc64le-linux/Dockerfile
index 9a290edd561..6b7b32a8bc7 100644
--- a/src/ci/docker/host-x86_64/dist-powerpc64le-linux/Dockerfile
+++ b/src/ci/docker/host-x86_64/dist-powerpc64le-linux/Dockerfile
@@ -24,5 +24,5 @@ ENV \
 
 ENV HOSTS=powerpc64le-unknown-linux-gnu
 
-ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
+ENV RUST_CONFIGURE_ARGS --enable-extended --enable-profiler --disable-docs
 ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-llvm-13/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-llvm-13/Dockerfile
index c3b47c3510d..06f15bd1211 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-llvm-13/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-llvm-13/Dockerfile
@@ -25,7 +25,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   zlib1g-dev \
   xz-utils \
   nodejs \
-
+  \
 # Install powershell so we can test x.ps1 on Linux
     apt-transport-https software-properties-common && \
     curl -s "https://packages.microsoft.com/config/ubuntu/$(lsb_release -rs)/packages-microsoft-prod.deb" > packages-microsoft-prod.deb && \
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
index 501d2781646..58c0c5db1a5 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
@@ -15,7 +15,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   sudo \
   xz-utils \
   tidy \
-
+  \
 # Install dependencies for chromium browser
   gconf-service \
   libasound2 \
diff --git a/src/librustdoc/config.rs b/src/librustdoc/config.rs
index e0cdb86d9d1..56b40d8c66b 100644
--- a/src/librustdoc/config.rs
+++ b/src/librustdoc/config.rs
@@ -69,6 +69,8 @@ pub(crate) struct Options {
     pub(crate) input: PathBuf,
     /// The name of the crate being documented.
     pub(crate) crate_name: Option<String>,
+    /// Whether or not this is a bin crate
+    pub(crate) bin_crate: bool,
     /// Whether or not this is a proc-macro crate
     pub(crate) proc_macro_crate: bool,
     /// How to format errors and warnings.
@@ -176,6 +178,7 @@ impl fmt::Debug for Options {
         f.debug_struct("Options")
             .field("input", &self.input)
             .field("crate_name", &self.crate_name)
+            .field("bin_crate", &self.bin_crate)
             .field("proc_macro_crate", &self.proc_macro_crate)
             .field("error_format", &self.error_format)
             .field("libs", &self.libs)
@@ -667,6 +670,7 @@ impl Options {
             None => OutputFormat::default(),
         };
         let crate_name = matches.opt_str("crate-name");
+        let bin_crate = crate_types.contains(&CrateType::Executable);
         let proc_macro_crate = crate_types.contains(&CrateType::ProcMacro);
         let playground_url = matches.opt_str("playground-url");
         let maybe_sysroot = matches.opt_str("sysroot").map(PathBuf::from);
@@ -718,6 +722,7 @@ impl Options {
             rustc_feature::UnstableFeatures::from_environment(crate_name.as_deref());
         let options = Options {
             input,
+            bin_crate,
             proc_macro_crate,
             error_format,
             diagnostic_width,
diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs
index 08f8096b07b..36d15ec3b86 100644
--- a/src/librustdoc/html/render/mod.rs
+++ b/src/librustdoc/html/render/mod.rs
@@ -2957,14 +2957,23 @@ fn render_call_locations(w: &mut Buffer, cx: &mut Context<'_>, item: &clean::Ite
 
     // The call locations are output in sequence, so that sequence needs to be determined.
     // Ideally the most "relevant" examples would be shown first, but there's no general algorithm
-    // for determining relevance. Instead, we prefer the smallest examples being likely the easiest to
-    // understand at a glance.
+    // for determining relevance. We instead proxy relevance with the following heuristics:
+    //   1. Code written to be an example is better than code not written to be an example, e.g.
+    //      a snippet from examples/foo.rs is better than src/lib.rs. We don't know the Cargo
+    //      directory structure in Rustdoc, so we proxy this by prioritizing code that comes from
+    //      a --crate-type bin.
+    //   2. Smaller examples are better than large examples. So we prioritize snippets that have
+    //      the smallest number of lines in their enclosing item.
+    //   3. Finally we sort by the displayed file name, which is arbitrary but prevents the
+    //      ordering of examples from randomly changing between Rustdoc invocations.
     let ordered_locations = {
-        let sort_criterion = |(_, call_data): &(_, &CallData)| {
+        fn sort_criterion<'a>(
+            (_, call_data): &(&PathBuf, &'a CallData),
+        ) -> (bool, u32, &'a String) {
             // Use the first location because that's what the user will see initially
             let (lo, hi) = call_data.locations[0].enclosing_item.byte_span;
-            hi - lo
-        };
+            (!call_data.is_bin, hi - lo, &call_data.display_name)
+        }
 
         let mut locs = call_locations.iter().collect::<Vec<_>>();
         locs.sort_by_key(sort_criterion);
diff --git a/src/librustdoc/html/static/css/rustdoc.css b/src/librustdoc/html/static/css/rustdoc.css
index 11136179607..afcb4022402 100644
--- a/src/librustdoc/html/static/css/rustdoc.css
+++ b/src/librustdoc/html/static/css/rustdoc.css
@@ -630,22 +630,16 @@ pre, .rustdoc.source .example-wrap {
 
 .docblock table {
 	margin: .5em 0;
-	width: calc(100% - 2px);
-	overflow-x: auto;
-	display: block;
 	border-collapse: collapse;
 }
 
-.docblock table td {
+.docblock table td, .docblock table th {
 	padding: .5em;
-	border: 1px dashed var(--border-color);
-	vertical-align: top;
+	border: 1px solid var(--border-color);
 }
 
-.docblock table th {
-	padding: .5em;
-	text-align: left;
-	border: 1px solid var(--border-color);
+.docblock table tbody tr:nth-child(2n) {
+	background: var(--table-alt-row-background-color);
 }
 
 /* Shift "where ..." part of method or fn definition down a line */
@@ -1813,6 +1807,22 @@ in storage.js
 	}
 }
 
+/* Should have min-width: (N + 1)px where N is the mobile breakpoint above. */
+@media (min-width: 701px) {
+	/* Places file-link for a scraped example on top of the example to save space.
+	   We only do this on large screens so the file-link doesn't overlap too much
+		 with the example's content. */
+	.scraped-example-title {
+		position: absolute;
+		z-index: 10;
+		background: var(--main-background-color);
+		bottom: 8px;
+		right: 5px;
+		padding: 2px 4px;
+		box-shadow: 0 0 4px var(--main-background-color);
+	}
+}
+
 @media print {
 	nav.sidebar, nav.sub, .out-of-band, a.srclink, #copy-path,
 	details.rustdoc-toggle[open] > summary::before, details.rustdoc-toggle > summary::before,
@@ -1899,6 +1909,11 @@ in storage.js
 	border-radius: 50px;
 }
 
+.scraped-example {
+	/* So .scraped-example-title can be positioned absolutely */
+	position: relative;
+}
+
 .scraped-example .code-wrapper {
 	position: relative;
 	display: flex;
@@ -1908,18 +1923,30 @@ in storage.js
 }
 
 .scraped-example:not(.expanded) .code-wrapper {
-	max-height: 240px;
+	/* scrape-examples.js has a constant DEFAULT_MAX_LINES (call it N) for the number
+	 * of lines shown in the un-expanded example code viewer. This pre needs to have
+	 * a max-height equal to line-height * N. The line-height is currently 1.5em,
+	 * and we include additional 10px for padding. */
+	 max-height: calc(1.5em * 5 + 10px);
 }
 
 .scraped-example:not(.expanded) .code-wrapper pre {
 	overflow-y: hidden;
-	max-height: 240px;
 	padding-bottom: 0;
+	/* See above comment, should be the same max-height. */
+	max-height: calc(1.5em * 5 + 10px);
+}
+
+.more-scraped-examples .scraped-example:not(.expanded) .code-wrapper,
+.more-scraped-examples .scraped-example:not(.expanded) .code-wrapper pre {
+	/* See above comment, except this height is based on HIDDEN_MAX_LINES. */
+	max-height: calc(1.5em * 10 + 10px);
 }
 
 .scraped-example .code-wrapper .next,
 .scraped-example .code-wrapper .prev,
 .scraped-example .code-wrapper .expand {
+	color: var(--main-color);
 	position: absolute;
 	top: 0.25em;
 	z-index: 1;
diff --git a/src/librustdoc/html/static/css/themes/ayu.css b/src/librustdoc/html/static/css/themes/ayu.css
index 6e0905e730d..0436fe0138e 100644
--- a/src/librustdoc/html/static/css/themes/ayu.css
+++ b/src/librustdoc/html/static/css/themes/ayu.css
@@ -87,6 +87,7 @@ Original by Dempfi (https://github.com/dempfi/ayu)
 	--crate-search-hover-border: #e0e0e0;
 	--source-sidebar-background-selected: #14191f;
 	--source-sidebar-background-hover: #14191f;
+	--table-alt-row-background-color: #191f26;
 }
 
 h1, h2, h3, h4 {
diff --git a/src/librustdoc/html/static/css/themes/dark.css b/src/librustdoc/html/static/css/themes/dark.css
index 334fc3de561..d945e956c53 100644
--- a/src/librustdoc/html/static/css/themes/dark.css
+++ b/src/librustdoc/html/static/css/themes/dark.css
@@ -82,6 +82,7 @@
 	--crate-search-hover-border: #2196f3;
 	--source-sidebar-background-selected: #333;
 	--source-sidebar-background-hover: #444;
+	--table-alt-row-background-color: #2A2A2A;
 }
 
 .content .item-info::before { color: #ccc; }
diff --git a/src/librustdoc/html/static/css/themes/light.css b/src/librustdoc/html/static/css/themes/light.css
index 453e7508af4..58955a79316 100644
--- a/src/librustdoc/html/static/css/themes/light.css
+++ b/src/librustdoc/html/static/css/themes/light.css
@@ -79,6 +79,7 @@
 	--crate-search-hover-border: #717171;
 	--source-sidebar-background-selected: #fff;
 	--source-sidebar-background-hover: #e0e0e0;
+	--table-alt-row-background-color: #F5F5F5;
 }
 
 .content .item-info::before { color: #ccc; }
diff --git a/src/librustdoc/html/static/js/main.js b/src/librustdoc/html/static/js/main.js
index 623f46b1096..152116089c7 100644
--- a/src/librustdoc/html/static/js/main.js
+++ b/src/librustdoc/html/static/js/main.js
@@ -622,7 +622,7 @@ function loadCss(cssUrl) {
         const innerToggle = document.getElementById(toggleAllDocsId);
         removeClass(innerToggle, "will-expand");
         onEachLazy(document.getElementsByClassName("rustdoc-toggle"), e => {
-            if (!hasClass(e, "type-contents-toggle")) {
+            if (!hasClass(e, "type-contents-toggle") && !hasClass(e, "more-examples-toggle")) {
                 e.open = true;
             }
         });
diff --git a/src/librustdoc/html/static/js/scrape-examples.js b/src/librustdoc/html/static/js/scrape-examples.js
index e328e656edd..7a3a9c5f340 100644
--- a/src/librustdoc/html/static/js/scrape-examples.js
+++ b/src/librustdoc/html/static/js/scrape-examples.js
@@ -3,25 +3,33 @@
 "use strict";
 
 (function() {
-    // Number of lines shown when code viewer is not expanded
-    const MAX_LINES = 10;
+    // Number of lines shown when code viewer is not expanded.
+    // DEFAULT is the first example shown by default, while HIDDEN is
+    // the examples hidden beneath the "More examples" toggle.
+    //
+    // NOTE: these values MUST be synchronized with certain rules in rustdoc.css!
+    const DEFAULT_MAX_LINES = 5;
+    const HIDDEN_MAX_LINES = 10;
 
     // Scroll code block to the given code location
-    function scrollToLoc(elt, loc) {
+    function scrollToLoc(elt, loc, isHidden) {
         const lines = elt.querySelector(".src-line-numbers");
         let scrollOffset;
 
         // If the block is greater than the size of the viewer,
         // then scroll to the top of the block. Otherwise scroll
         // to the middle of the block.
-        if (loc[1] - loc[0] > MAX_LINES) {
+        const maxLines = isHidden ? HIDDEN_MAX_LINES : DEFAULT_MAX_LINES;
+        if (loc[1] - loc[0] > maxLines) {
             const line = Math.max(0, loc[0] - 1);
             scrollOffset = lines.children[line].offsetTop;
         } else {
             const wrapper = elt.querySelector(".code-wrapper");
             const halfHeight = wrapper.offsetHeight / 2;
-            const offsetMid = (lines.children[loc[0]].offsetTop
-                             + lines.children[loc[1]].offsetTop) / 2;
+            const offsetTop = lines.children[loc[0]].offsetTop;
+            const lastLine = lines.children[loc[1]];
+            const offsetBot = lastLine.offsetTop + lastLine.offsetHeight;
+            const offsetMid = (offsetTop + offsetBot) / 2;
             scrollOffset = offsetMid - halfHeight;
         }
 
@@ -29,7 +37,7 @@
         elt.querySelector(".rust").scrollTo(0, scrollOffset);
     }
 
-    function updateScrapedExample(example) {
+    function updateScrapedExample(example, isHidden) {
         const locs = JSON.parse(example.attributes.getNamedItem("data-locs").textContent);
         let locIndex = 0;
         const highlights = Array.prototype.slice.call(example.querySelectorAll(".highlight"));
@@ -40,7 +48,7 @@
             const onChangeLoc = changeIndex => {
                 removeClass(highlights[locIndex], "focus");
                 changeIndex();
-                scrollToLoc(example, locs[locIndex][0]);
+                scrollToLoc(example, locs[locIndex][0], isHidden);
                 addClass(highlights[locIndex], "focus");
 
                 const url = locs[locIndex][1];
@@ -70,7 +78,7 @@
             expandButton.addEventListener("click", () => {
                 if (hasClass(example, "expanded")) {
                     removeClass(example, "expanded");
-                    scrollToLoc(example, locs[0][0]);
+                    scrollToLoc(example, locs[0][0], isHidden);
                 } else {
                     addClass(example, "expanded");
                 }
@@ -78,11 +86,11 @@
         }
 
         // Start with the first example in view
-        scrollToLoc(example, locs[0][0]);
+        scrollToLoc(example, locs[0][0], isHidden);
     }
 
     const firstExamples = document.querySelectorAll(".scraped-example-list > .scraped-example");
-    onEachLazy(firstExamples, updateScrapedExample);
+    onEachLazy(firstExamples, el => updateScrapedExample(el, false));
     onEachLazy(document.querySelectorAll(".more-examples-toggle"), toggle => {
         // Allow users to click the left border of the <details> section to close it,
         // since the section can be large and finding the [+] button is annoying.
@@ -99,7 +107,7 @@
             // depends on offsetHeight, a property that requires an element to be visible to
             // compute correctly.
             setTimeout(() => {
-                onEachLazy(moreExamples, updateScrapedExample);
+                onEachLazy(moreExamples, el => updateScrapedExample(el, true));
             });
         }, {once: true});
     });
diff --git a/src/librustdoc/html/static/scrape-examples-help.md b/src/librustdoc/html/static/scrape-examples-help.md
index 035b2e18b00..002d19ec9b6 100644
--- a/src/librustdoc/html/static/scrape-examples-help.md
+++ b/src/librustdoc/html/static/scrape-examples-help.md
@@ -1,4 +1,4 @@
-Rustdoc will automatically scrape examples of documented items from the `examples/` directory of a project. These examples will be included within the generated documentation for that item. For example, if your library contains a public function:
+Rustdoc will automatically scrape examples of documented items from a project's source code. These examples will be included within the generated documentation for that item. For example, if your library contains a public function:
 
 ```rust
 // src/lib.rs
@@ -16,6 +16,7 @@ fn main() {
 
 Then this code snippet will be included in the documentation for `a_func`.
 
+
 ## How to read scraped examples
 
 Scraped examples are shown as blocks of code from a given file. The relevant item will be highlighted. If the file is larger than a couple lines, only a small window will be shown which you can expand by clicking &varr; in the top-right. If a file contains multiple instances of an item, you can use the &pr; and &sc; buttons to toggle through each instance.
@@ -25,7 +26,7 @@ If there is more than one file that contains examples, then you should click "Mo
 
 ## How Rustdoc scrapes examples
 
-When you run `cargo doc`, Rustdoc will analyze all the crates that match Cargo's `--examples` filter for instances of items that occur in the crates being documented. Then Rustdoc will include the source code of these instances in the generated documentation.
+When you run `cargo doc -Zunstable-options -Zrustdoc-scrape-examples`, Rustdoc will analyze all the documented crates for uses of documented items. Then Rustdoc will include the source code of these instances in the generated documentation.
 
 Rustdoc has a few techniques to ensure this doesn't overwhelm documentation readers, and that it doesn't blow up the page size:
 
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index 6d34f484754..ef1d7da5a34 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -674,7 +674,7 @@ type MainResult = Result<(), ErrorGuaranteed>;
 
 fn wrap_return(diag: &rustc_errors::Handler, res: Result<(), String>) -> MainResult {
     match res {
-        Ok(()) => Ok(()),
+        Ok(()) => diag.has_errors().map_or(Ok(()), Err),
         Err(err) => {
             let reported = diag.struct_err(&err).emit();
             Err(reported)
@@ -689,7 +689,7 @@ fn run_renderer<'tcx, T: formats::FormatRenderer<'tcx>>(
     tcx: TyCtxt<'tcx>,
 ) -> MainResult {
     match formats::run_format::<T>(krate, renderopts, cache, tcx) {
-        Ok(_) => Ok(()),
+        Ok(_) => tcx.sess.has_errors().map_or(Ok(()), Err),
         Err(e) => {
             let mut msg =
                 tcx.sess.struct_err(&format!("couldn't generate documentation: {}", e.error));
@@ -774,6 +774,7 @@ fn main_args(at_args: &[String]) -> MainResult {
     let output_format = options.output_format;
     let externs = options.externs.clone();
     let scrape_examples_options = options.scrape_examples_options.clone();
+    let bin_crate = options.bin_crate;
 
     let config = core::create_config(options);
 
@@ -832,7 +833,14 @@ fn main_args(at_args: &[String]) -> MainResult {
                 info!("finished with rustc");
 
                 if let Some(options) = scrape_examples_options {
-                    return scrape_examples::run(krate, render_opts, cache, tcx, options);
+                    return scrape_examples::run(
+                        krate,
+                        render_opts,
+                        cache,
+                        tcx,
+                        options,
+                        bin_crate,
+                    );
                 }
 
                 cache.crate_version = crate_version;
diff --git a/src/librustdoc/scrape_examples.rs b/src/librustdoc/scrape_examples.rs
index dfa6ba38b88..f2ee99cd9d4 100644
--- a/src/librustdoc/scrape_examples.rs
+++ b/src/librustdoc/scrape_examples.rs
@@ -110,6 +110,7 @@ pub(crate) struct CallData {
     pub(crate) url: String,
     pub(crate) display_name: String,
     pub(crate) edition: Edition,
+    pub(crate) is_bin: bool,
 }
 
 pub(crate) type FnCallLocations = FxHashMap<PathBuf, CallData>;
@@ -122,6 +123,7 @@ struct FindCalls<'a, 'tcx> {
     cx: Context<'tcx>,
     target_crates: Vec<CrateNum>,
     calls: &'a mut AllCallLocations,
+    bin_crate: bool,
 }
 
 impl<'a, 'tcx> Visitor<'tcx> for FindCalls<'a, 'tcx>
@@ -245,7 +247,9 @@ where
                 let mk_call_data = || {
                     let display_name = file_path.display().to_string();
                     let edition = call_span.edition();
-                    CallData { locations: Vec::new(), url, display_name, edition }
+                    let is_bin = self.bin_crate;
+
+                    CallData { locations: Vec::new(), url, display_name, edition, is_bin }
                 };
 
                 let fn_key = tcx.def_path_hash(*def_id);
@@ -274,6 +278,7 @@ pub(crate) fn run(
     cache: formats::cache::Cache,
     tcx: TyCtxt<'_>,
     options: ScrapeExamplesOptions,
+    bin_crate: bool,
 ) -> interface::Result<()> {
     let inner = move || -> Result<(), String> {
         // Generates source files for examples
@@ -300,7 +305,8 @@ pub(crate) fn run(
 
         // Run call-finder on all items
         let mut calls = FxHashMap::default();
-        let mut finder = FindCalls { calls: &mut calls, tcx, map: tcx.hir(), cx, target_crates };
+        let mut finder =
+            FindCalls { calls: &mut calls, tcx, map: tcx.hir(), cx, target_crates, bin_crate };
         tcx.hir().visit_all_item_likes_in_crate(&mut finder);
 
         // The visitor might have found a type error, which we need to
diff --git a/src/llvm-project b/src/llvm-project
-Subproject a1232c451fc27173f8718e05d174b2503ca0b60
+Subproject 3dfd4d93fa013e1c0578d3ceac5c8f4ebba4b6e
diff --git a/src/test/mir-opt/inline/inline_retag.bar.Inline.after.mir b/src/test/mir-opt/inline/inline_retag.bar.Inline.after.mir
index 75af20d482d..60149ff3606 100644
--- a/src/test/mir-opt/inline/inline_retag.bar.Inline.after.mir
+++ b/src/test/mir-opt/inline/inline_retag.bar.Inline.after.mir
@@ -38,9 +38,7 @@ fn bar() -> bool {
                                          // + literal: Const { ty: &i32, val: Unevaluated(bar, [], Some(promoted[1])) }
         Retag(_10);                      // scope 1 at $DIR/inline_retag.rs:+2:7: +2:9
         _4 = &(*_10);                    // scope 1 at $DIR/inline_retag.rs:+2:7: +2:9
-        Retag(_4);                       // scope 1 at $DIR/inline_retag.rs:+2:7: +2:9
         _3 = &(*_4);                     // scope 1 at $DIR/inline_retag.rs:+2:7: +2:9
-        Retag(_3);                       // scope 1 at $DIR/inline_retag.rs:+2:7: +2:9
         StorageLive(_6);                 // scope 1 at $DIR/inline_retag.rs:+2:11: +2:14
         StorageLive(_7);                 // scope 1 at $DIR/inline_retag.rs:+2:11: +2:14
         _9 = const _;                    // scope 1 at $DIR/inline_retag.rs:+2:11: +2:14
@@ -49,9 +47,7 @@ fn bar() -> bool {
                                          // + literal: Const { ty: &i32, val: Unevaluated(bar, [], Some(promoted[0])) }
         Retag(_9);                       // scope 1 at $DIR/inline_retag.rs:+2:11: +2:14
         _7 = &(*_9);                     // scope 1 at $DIR/inline_retag.rs:+2:11: +2:14
-        Retag(_7);                       // scope 1 at $DIR/inline_retag.rs:+2:11: +2:14
         _6 = &(*_7);                     // scope 1 at $DIR/inline_retag.rs:+2:11: +2:14
-        Retag(_6);                       // scope 1 at $DIR/inline_retag.rs:+2:11: +2:14
         Retag(_3);                       // scope 2 at $DIR/inline_retag.rs:16:8: 16:9
         Retag(_6);                       // scope 2 at $DIR/inline_retag.rs:16:17: 16:18
         StorageLive(_11);                // scope 2 at $DIR/inline_retag.rs:17:5: 17:7
diff --git a/src/test/mir-opt/retag.array_casts.SimplifyCfg-elaborate-drops.after.mir b/src/test/mir-opt/retag.array_casts.SimplifyCfg-elaborate-drops.after.mir
index fe57e32a7ac..7b69b3e07d6 100644
--- a/src/test/mir-opt/retag.array_casts.SimplifyCfg-elaborate-drops.after.mir
+++ b/src/test/mir-opt/retag.array_casts.SimplifyCfg-elaborate-drops.after.mir
@@ -68,9 +68,7 @@ fn array_casts() -> () {
         StorageLive(_3);                 // scope 1 at $DIR/retag.rs:+2:13: +2:19
         StorageLive(_4);                 // scope 1 at $DIR/retag.rs:+2:13: +2:19
         _4 = &mut _1;                    // scope 1 at $DIR/retag.rs:+2:13: +2:19
-        Retag(_4);                       // scope 1 at $DIR/retag.rs:+2:13: +2:19
         _3 = &raw mut (*_4);             // scope 1 at $DIR/retag.rs:+2:13: +2:19
-        Retag([raw] _3);                 // scope 1 at $DIR/retag.rs:+2:13: +2:19
         _2 = move _3 as *mut usize (Pointer(ArrayToPointer)); // scope 1 at $DIR/retag.rs:+2:13: +2:33
         StorageDead(_3);                 // scope 1 at $DIR/retag.rs:+2:32: +2:33
         StorageDead(_4);                 // scope 1 at $DIR/retag.rs:+2:33: +2:34
@@ -96,9 +94,7 @@ fn array_casts() -> () {
         StorageLive(_10);                // scope 4 at $DIR/retag.rs:+6:13: +6:15
         StorageLive(_11);                // scope 4 at $DIR/retag.rs:+6:13: +6:15
         _11 = &_8;                       // scope 4 at $DIR/retag.rs:+6:13: +6:15
-        Retag(_11);                      // scope 4 at $DIR/retag.rs:+6:13: +6:15
         _10 = &raw const (*_11);         // scope 4 at $DIR/retag.rs:+6:13: +6:15
-        Retag([raw] _10);                // scope 4 at $DIR/retag.rs:+6:13: +6:15
         _9 = move _10 as *const usize (Pointer(ArrayToPointer)); // scope 4 at $DIR/retag.rs:+6:13: +6:31
         StorageDead(_10);                // scope 4 at $DIR/retag.rs:+6:30: +6:31
         StorageDead(_11);                // scope 4 at $DIR/retag.rs:+6:31: +6:32
@@ -119,7 +115,6 @@ fn array_casts() -> () {
         StorageDead(_17);                // scope 6 at $DIR/retag.rs:+7:33: +7:34
         _15 = (*_16);                    // scope 6 at $DIR/retag.rs:+7:25: +7:34
         _14 = &_15;                      // scope 5 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
-        Retag(_14);                      // scope 5 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
         StorageLive(_18);                // scope 5 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
         _35 = const _;                   // scope 5 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
                                          // mir::Constant
@@ -127,7 +122,6 @@ fn array_casts() -> () {
                                          // + literal: Const { ty: &usize, val: Unevaluated(array_casts, [], Some(promoted[0])) }
         Retag(_35);                      // scope 5 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
         _18 = &(*_35);                   // scope 5 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
-        Retag(_18);                      // scope 5 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
         Deinit(_13);                     // scope 5 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
         (_13.0: &usize) = move _14;      // scope 5 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
         (_13.1: &usize) = move _18;      // scope 5 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
@@ -164,15 +158,11 @@ fn array_casts() -> () {
         StorageLive(_30);                // scope 8 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
         StorageLive(_31);                // scope 8 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
         _31 = &(*_20);                   // scope 8 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
-        Retag(_31);                      // scope 8 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
         _30 = &(*_31);                   // scope 8 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
-        Retag(_30);                      // scope 8 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
         StorageLive(_32);                // scope 8 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
         StorageLive(_33);                // scope 8 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
         _33 = &(*_21);                   // scope 8 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
-        Retag(_33);                      // scope 8 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
         _32 = &(*_33);                   // scope 8 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
-        Retag(_32);                      // scope 8 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
         StorageLive(_34);                // scope 8 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
         Deinit(_34);                     // scope 8 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
         discriminant(_34) = 0;           // scope 8 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
diff --git a/src/test/mir-opt/retag.core.ptr-drop_in_place.Test.SimplifyCfg-make_shim.after.mir b/src/test/mir-opt/retag.core.ptr-drop_in_place.Test.SimplifyCfg-make_shim.after.mir
index cdc413c568f..14f297e948b 100644
--- a/src/test/mir-opt/retag.core.ptr-drop_in_place.Test.SimplifyCfg-make_shim.after.mir
+++ b/src/test/mir-opt/retag.core.ptr-drop_in_place.Test.SimplifyCfg-make_shim.after.mir
@@ -6,7 +6,6 @@ fn std::ptr::drop_in_place(_1: *mut Test) -> () {
     let mut _3: ();                      // in scope 0 at $SRC_DIR/core/src/ptr/mod.rs:+0:1: +0:56
 
     bb0: {
-        Retag([raw] _1);                 // scope 0 at $SRC_DIR/core/src/ptr/mod.rs:+0:1: +0:56
         _2 = &mut (*_1);                 // scope 0 at $SRC_DIR/core/src/ptr/mod.rs:+0:1: +0:56
         _3 = <Test as Drop>::drop(move _2) -> bb1; // scope 0 at $SRC_DIR/core/src/ptr/mod.rs:+0:1: +0:56
                                          // mir::Constant
diff --git a/src/test/mir-opt/retag.main-{closure#0}.SimplifyCfg-elaborate-drops.after.mir b/src/test/mir-opt/retag.main-{closure#0}.SimplifyCfg-elaborate-drops.after.mir
index 96fc7e6493a..9e5c119a2b2 100644
--- a/src/test/mir-opt/retag.main-{closure#0}.SimplifyCfg-elaborate-drops.after.mir
+++ b/src/test/mir-opt/retag.main-{closure#0}.SimplifyCfg-elaborate-drops.after.mir
@@ -15,7 +15,6 @@ fn main::{closure#0}(_1: &[closure@main::{closure#0}], _2: &i32) -> &i32 {
         _3 = _2;                         // scope 0 at $DIR/retag.rs:+1:18: +1:19
         Retag(_3);                       // scope 0 at $DIR/retag.rs:+1:18: +1:19
         _0 = &(*_2);                     // scope 1 at $DIR/retag.rs:+2:9: +2:10
-        Retag(_0);                       // scope 1 at $DIR/retag.rs:+2:9: +2:10
         StorageDead(_3);                 // scope 0 at $DIR/retag.rs:+3:5: +3:6
         return;                          // scope 0 at $DIR/retag.rs:+3:6: +3:6
     }
diff --git a/src/test/mir-opt/retag.main.SimplifyCfg-elaborate-drops.after.mir b/src/test/mir-opt/retag.main.SimplifyCfg-elaborate-drops.after.mir
index 81225b44ebf..b853e450541 100644
--- a/src/test/mir-opt/retag.main.SimplifyCfg-elaborate-drops.after.mir
+++ b/src/test/mir-opt/retag.main.SimplifyCfg-elaborate-drops.after.mir
@@ -65,13 +65,10 @@ fn main() -> () {
         Deinit(_5);                      // scope 1 at $DIR/retag.rs:+3:17: +3:24
         (_5.0: i32) = const 0_i32;       // scope 1 at $DIR/retag.rs:+3:17: +3:24
         _4 = &_5;                        // scope 1 at $DIR/retag.rs:+3:17: +3:36
-        Retag(_4);                       // scope 1 at $DIR/retag.rs:+3:17: +3:36
         StorageLive(_6);                 // scope 1 at $DIR/retag.rs:+3:29: +3:35
         StorageLive(_7);                 // scope 1 at $DIR/retag.rs:+3:29: +3:35
         _7 = &mut _1;                    // scope 1 at $DIR/retag.rs:+3:29: +3:35
-        Retag(_7);                       // scope 1 at $DIR/retag.rs:+3:29: +3:35
         _6 = &mut (*_7);                 // scope 1 at $DIR/retag.rs:+3:29: +3:35
-        Retag([2phase] _6);              // scope 1 at $DIR/retag.rs:+3:29: +3:35
         _3 = Test::foo(move _4, move _6) -> [return: bb1, unwind: bb8]; // scope 1 at $DIR/retag.rs:+3:17: +3:36
                                          // mir::Constant
                                          // + span: $DIR/retag.rs:33:25: 33:28
@@ -93,7 +90,6 @@ fn main() -> () {
         _9 = move _3;                    // scope 2 at $DIR/retag.rs:+4:19: +4:20
         Retag(_9);                       // scope 2 at $DIR/retag.rs:+4:19: +4:20
         _8 = &mut (*_9);                 // scope 2 at $DIR/retag.rs:+4:19: +4:20
-        Retag(_8);                       // scope 2 at $DIR/retag.rs:+4:19: +4:20
         StorageDead(_9);                 // scope 2 at $DIR/retag.rs:+4:22: +4:23
         StorageLive(_10);                // scope 3 at $DIR/retag.rs:+5:13: +5:14
         _10 = move _8;                   // scope 3 at $DIR/retag.rs:+5:17: +5:18
@@ -101,7 +97,6 @@ fn main() -> () {
         StorageLive(_11);                // scope 4 at $DIR/retag.rs:+7:13: +7:15
         StorageLive(_12);                // scope 4 at $DIR/retag.rs:+7:18: +7:29
         _12 = &raw mut (*_10);           // scope 4 at $DIR/retag.rs:+7:18: +7:19
-        Retag([raw] _12);                // scope 4 at $DIR/retag.rs:+7:18: +7:19
         _11 = _12;                       // scope 4 at $DIR/retag.rs:+7:18: +7:29
         StorageDead(_12);                // scope 4 at $DIR/retag.rs:+7:29: +7:30
         _2 = const ();                   // scope 1 at $DIR/retag.rs:+2:5: +8:6
@@ -122,9 +117,7 @@ fn main() -> () {
         StorageLive(_17);                // scope 6 at $DIR/retag.rs:+15:16: +15:18
         StorageLive(_18);                // scope 6 at $DIR/retag.rs:+15:16: +15:18
         _18 = &_1;                       // scope 6 at $DIR/retag.rs:+15:16: +15:18
-        Retag(_18);                      // scope 6 at $DIR/retag.rs:+15:16: +15:18
         _17 = &(*_18);                   // scope 6 at $DIR/retag.rs:+15:16: +15:18
-        Retag(_17);                      // scope 6 at $DIR/retag.rs:+15:16: +15:18
         _15 = move _16(move _17) -> bb3; // scope 6 at $DIR/retag.rs:+15:14: +15:19
     }
 
@@ -139,7 +132,6 @@ fn main() -> () {
         Deinit(_21);                     // scope 7 at $DIR/retag.rs:+18:5: +18:12
         (_21.0: i32) = const 0_i32;      // scope 7 at $DIR/retag.rs:+18:5: +18:12
         _20 = &_21;                      // scope 7 at $DIR/retag.rs:+18:5: +18:24
-        Retag(_20);                      // scope 7 at $DIR/retag.rs:+18:5: +18:24
         StorageLive(_22);                // scope 7 at $DIR/retag.rs:+18:21: +18:23
         StorageLive(_23);                // scope 7 at $DIR/retag.rs:+18:21: +18:23
         _28 = const _;                   // scope 7 at $DIR/retag.rs:+18:21: +18:23
@@ -148,9 +140,7 @@ fn main() -> () {
                                          // + literal: Const { ty: &i32, val: Unevaluated(main, [], Some(promoted[0])) }
         Retag(_28);                      // scope 7 at $DIR/retag.rs:+18:21: +18:23
         _23 = &(*_28);                   // scope 7 at $DIR/retag.rs:+18:21: +18:23
-        Retag(_23);                      // scope 7 at $DIR/retag.rs:+18:21: +18:23
         _22 = &(*_23);                   // scope 7 at $DIR/retag.rs:+18:21: +18:23
-        Retag(_22);                      // scope 7 at $DIR/retag.rs:+18:21: +18:23
         _19 = Test::foo_shr(move _20, move _22) -> [return: bb4, unwind: bb7]; // scope 7 at $DIR/retag.rs:+18:5: +18:24
                                          // mir::Constant
                                          // + span: $DIR/retag.rs:48:13: 48:20
@@ -171,7 +161,6 @@ fn main() -> () {
         StorageLive(_25);                // scope 7 at $DIR/retag.rs:+21:9: +21:11
         StorageLive(_26);                // scope 7 at $DIR/retag.rs:+21:14: +21:28
         _26 = &raw const (*_15);         // scope 7 at $DIR/retag.rs:+21:14: +21:16
-        Retag([raw] _26);                // scope 7 at $DIR/retag.rs:+21:14: +21:16
         _25 = _26;                       // scope 7 at $DIR/retag.rs:+21:14: +21:28
         StorageDead(_26);                // scope 7 at $DIR/retag.rs:+21:28: +21:29
         StorageLive(_27);                // scope 8 at $DIR/retag.rs:+23:5: +23:18
diff --git a/src/test/mir-opt/retag.{impl#0}-foo.SimplifyCfg-elaborate-drops.after.mir b/src/test/mir-opt/retag.{impl#0}-foo.SimplifyCfg-elaborate-drops.after.mir
index 08fd655ae29..4b50205fa80 100644
--- a/src/test/mir-opt/retag.{impl#0}-foo.SimplifyCfg-elaborate-drops.after.mir
+++ b/src/test/mir-opt/retag.{impl#0}-foo.SimplifyCfg-elaborate-drops.after.mir
@@ -11,9 +11,7 @@ fn <impl at $DIR/retag.rs:12:1: 12:10>::foo(_1: &Test, _2: &mut i32) -> &mut i32
         Retag([fn entry] _2);            // scope 0 at $DIR/retag.rs:+0:23: +0:24
         StorageLive(_3);                 // scope 0 at $DIR/retag.rs:+1:9: +1:10
         _3 = &mut (*_2);                 // scope 0 at $DIR/retag.rs:+1:9: +1:10
-        Retag(_3);                       // scope 0 at $DIR/retag.rs:+1:9: +1:10
         _0 = &mut (*_3);                 // scope 0 at $DIR/retag.rs:+1:9: +1:10
-        Retag(_0);                       // scope 0 at $DIR/retag.rs:+1:9: +1:10
         StorageDead(_3);                 // scope 0 at $DIR/retag.rs:+2:5: +2:6
         return;                          // scope 0 at $DIR/retag.rs:+2:6: +2:6
     }
diff --git a/src/test/run-make-fulldeps/hotplug_codegen_backend/the_backend.rs b/src/test/run-make-fulldeps/hotplug_codegen_backend/the_backend.rs
index 2c4309fbe66..3aa57d58908 100644
--- a/src/test/run-make-fulldeps/hotplug_codegen_backend/the_backend.rs
+++ b/src/test/run-make-fulldeps/hotplug_codegen_backend/the_backend.rs
@@ -67,7 +67,7 @@ impl CodegenBackend for TheBackend {
             if crate_type != CrateType::Rlib {
                 sess.fatal(&format!("Crate type is {:?}", crate_type));
             }
-            let output_name = out_filename(sess, crate_type, &outputs, &*crate_name.as_str());
+            let output_name = out_filename(sess, crate_type, &outputs, crate_name);
             let mut out_file = ::std::fs::File::create(output_name).unwrap();
             write!(out_file, "This has been \"compiled\" successfully.").unwrap();
         }
diff --git a/src/test/run-make/coverage-reports/Makefile b/src/test/run-make/coverage-reports/Makefile
index 436aebf1174..d06cd9c6a54 100644
--- a/src/test/run-make/coverage-reports/Makefile
+++ b/src/test/run-make/coverage-reports/Makefile
@@ -80,7 +80,7 @@ ifdef RUSTC_BLESS_TEST
 	rm -f expected_*
 endif
 
-include clear_expected_if_blessed
+-include clear_expected_if_blessed
 
 %: $(SOURCEDIR)/lib/%.rs
 	# Compile the test library with coverage instrumentation
diff --git a/src/test/rustdoc-gui/basic.goml b/src/test/rustdoc-gui/basic.goml
deleted file mode 100644
index 60292835bc0..00000000000
--- a/src/test/rustdoc-gui/basic.goml
+++ /dev/null
@@ -1,4 +0,0 @@
-goto: "file://" + |DOC_PATH| + "/test_docs/index.html"
-assert: ("#functions")
-goto: "./struct.Foo.html"
-assert: ("div.item-decl")
diff --git a/src/test/rustdoc-gui/docblock-table.goml b/src/test/rustdoc-gui/docblock-table.goml
index 4e316ce0bcb..8645c1b1949 100644
--- a/src/test/rustdoc-gui/docblock-table.goml
+++ b/src/test/rustdoc-gui/docblock-table.goml
@@ -2,3 +2,50 @@ goto: "file://" + |DOC_PATH| + "/test_docs/doc_block_table/struct.DocBlockTable.
 
 compare-elements-css: (".impl-items .docblock table th", ".top-doc .docblock table th", ["border"])
 compare-elements-css: (".impl-items .docblock table td", ".top-doc .docblock table td", ["border"])
+
+define-function: (
+    "check-colors",
+    (theme, border_color, zebra_stripe_color),
+    [
+        ("local-storage", {"rustdoc-use-system-theme": "false", "rustdoc-theme": |theme|}),
+        ("reload"),
+        ("assert-css", (".top-doc .docblock table tbody tr:nth-child(1)", {
+            "background-color": "rgba(0, 0, 0, 0)",
+        })),
+        ("assert-css", (".top-doc .docblock table tbody tr:nth-child(2)", {
+            "background-color": |zebra_stripe_color|,
+        })),
+        ("assert-css", (".top-doc .docblock table tbody tr:nth-child(3)", {
+            "background-color": "rgba(0, 0, 0, 0)",
+        })),
+        ("assert-css", (".top-doc .docblock table tbody tr:nth-child(4)", {
+            "background-color": |zebra_stripe_color|,
+        })),
+        ("assert-css", (".top-doc .docblock table td", {
+            "border-style": "solid",
+            "border-width": "1px",
+            "border-color": |border_color|,
+        })),
+        ("assert-css", (".top-doc .docblock table th", {
+            "border-style": "solid",
+            "border-width": "1px",
+            "border-color": |border_color|,
+        })),
+    ]
+)
+
+call-function: ("check-colors", {
+    "theme": "dark",
+    "border_color": "rgb(224, 224, 224)",
+    "zebra_stripe_color": "rgb(42, 42, 42)",
+})
+call-function: ("check-colors", {
+    "theme": "ayu",
+    "border_color": "rgb(92, 103, 115)",
+    "zebra_stripe_color": "rgb(25, 31, 38)",
+})
+call-function: ("check-colors", {
+    "theme": "light",
+    "border_color": "rgb(224, 224, 224)",
+    "zebra_stripe_color": "rgb(245, 245, 245)",
+})
diff --git a/src/test/rustdoc-gui/scrape-examples-button-focus.goml b/src/test/rustdoc-gui/scrape-examples-button-focus.goml
index a222139f1dc..bba518db099 100644
--- a/src/test/rustdoc-gui/scrape-examples-button-focus.goml
+++ b/src/test/rustdoc-gui/scrape-examples-button-focus.goml
@@ -1,5 +1,6 @@
 goto: "file://" + |DOC_PATH| + "/scrape_examples/fn.test.html"
 
+// The next/prev buttons vertically scroll the code viewport between examples
 store-property: (initialScrollTop, ".scraped-example-list > .scraped-example pre", "scrollTop")
 focus: ".scraped-example-list > .scraped-example .next"
 press-key: "Enter"
@@ -12,6 +13,7 @@ assert-property: (".scraped-example-list > .scraped-example pre", {
 	"scrollTop": |initialScrollTop|
 })
 
+// The expand button increases the scrollHeight of the minimized code viewport
 store-property: (smallOffsetHeight, ".scraped-example-list > .scraped-example pre", "offsetHeight")
 assert-property-false: (".scraped-example-list > .scraped-example pre", {
 	"scrollHeight": |smallOffsetHeight|
diff --git a/src/test/rustdoc-gui/scrape-examples-toggle.goml b/src/test/rustdoc-gui/scrape-examples-toggle.goml
new file mode 100644
index 00000000000..ee720afb788
--- /dev/null
+++ b/src/test/rustdoc-gui/scrape-examples-toggle.goml
@@ -0,0 +1,14 @@
+goto: "file://" + |DOC_PATH| + "/scrape_examples/fn.test_many.html"
+
+// Clicking "More examples..." will open additional examples
+assert-attribute-false: (".more-examples-toggle", {"open": ""})
+click: ".more-examples-toggle"
+assert-attribute: (".more-examples-toggle", {"open": ""})
+
+// Toggling all docs will close additional examples
+click: "#toggle-all-docs"
+assert-attribute-false: (".more-examples-toggle", {"open": ""})
+
+// After re-opening the docs, the additional examples should stay closed
+click: "#toggle-all-docs"
+assert-attribute-false: (".more-examples-toggle", {"open": ""})
diff --git a/src/test/rustdoc-gui/src/test_docs/lib.rs b/src/test/rustdoc-gui/src/test_docs/lib.rs
index 1340511d472..d6eeab803df 100644
--- a/src/test/rustdoc-gui/src/test_docs/lib.rs
+++ b/src/test/rustdoc-gui/src/test_docs/lib.rs
@@ -343,6 +343,9 @@ pub mod doc_block_table {
     /// | header1                  | header2                  |
     /// |--------------------------|--------------------------|
     /// | Lorem Ipsum, Lorem Ipsum | Lorem Ipsum, Lorem Ipsum |
+    /// | Lorem Ipsum, Lorem Ipsum | Lorem Ipsum, Lorem Ipsum |
+    /// | Lorem Ipsum, Lorem Ipsum | Lorem Ipsum, Lorem Ipsum |
+    /// | Lorem Ipsum, Lorem Ipsum | Lorem Ipsum, Lorem Ipsum |
     pub struct DocBlockTable {}
 
     impl DocBlockTableTrait for DocBlockTable {
diff --git a/src/test/rustdoc/const-evalutation-ice.rs b/src/test/rustdoc-ui/const-evalutation-ice.rs
index 68c7f9c5686..0dd3bcaa289 100644
--- a/src/test/rustdoc/const-evalutation-ice.rs
+++ b/src/test/rustdoc-ui/const-evalutation-ice.rs
@@ -7,4 +7,5 @@ pub struct S {
     s: Cell<usize>
 }
 
-pub const N: usize = 0 - (mem::size_of::<S>() != 4) as usize;
+pub const N: usize = 0 - (mem::size_of::<S>() != 400) as usize;
+//~^ ERROR evaluation of constant value failed
diff --git a/src/test/rustdoc-ui/const-evalutation-ice.stderr b/src/test/rustdoc-ui/const-evalutation-ice.stderr
new file mode 100644
index 00000000000..5d9c16c0765
--- /dev/null
+++ b/src/test/rustdoc-ui/const-evalutation-ice.stderr
@@ -0,0 +1,9 @@
+error[E0080]: evaluation of constant value failed
+  --> $DIR/const-evalutation-ice.rs:10:22
+   |
+LL | pub const N: usize = 0 - (mem::size_of::<S>() != 400) as usize;
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ attempt to compute `0_usize - 1_usize`, which would overflow
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0080`.
diff --git a/src/test/ui/async-await/in-trait/nested-rpit.rs b/src/test/ui/async-await/in-trait/nested-rpit.rs
new file mode 100644
index 00000000000..ae8e0aed0cc
--- /dev/null
+++ b/src/test/ui/async-await/in-trait/nested-rpit.rs
@@ -0,0 +1,17 @@
+// check-pass
+// edition: 2021
+
+#![feature(async_fn_in_trait)]
+#![feature(return_position_impl_trait_in_trait)]
+#![allow(incomplete_features)]
+
+use std::future::Future;
+use std::marker::PhantomData;
+
+trait Lockable<K, V> {
+    async fn lock_all_entries(&self) -> impl Future<Output = Guard<'_>>;
+}
+
+struct Guard<'a>(PhantomData<&'a ()>);
+
+fn main() {}
diff --git a/src/test/ui/diagnostic-width/long-E0308.rs b/src/test/ui/diagnostic-width/long-E0308.rs
new file mode 100644
index 00000000000..3fd7a7110fd
--- /dev/null
+++ b/src/test/ui/diagnostic-width/long-E0308.rs
@@ -0,0 +1,86 @@
+// compile-flags: --diagnostic-width=60
+// normalize-stderr-test: "long-type-\d+" -> "long-type-hash"
+
+struct Atype<T, K>(T, K);
+struct Btype<T, K>(T, K);
+struct Ctype<T, K>(T, K);
+
+fn main() {
+    let x: Atype<
+      Btype<
+        Ctype<
+          Atype<
+            Btype<
+              Ctype<
+                Atype<
+                  Btype<
+                    Ctype<i32, i32>,
+                    i32
+                  >,
+                  i32
+                >,
+                i32
+              >,
+              i32
+            >,
+            i32
+          >,
+          i32
+        >,
+        i32
+      >,
+      i32
+    > = Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(
+        Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(
+            Ok("")
+        ))))))))))))))))))))))))))))))
+    ))))))))))))))))))))))))))))));
+    //~^^^^^ ERROR E0308
+
+    let _ = Some(Ok(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(
+        Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(
+            Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(Some(
+                Some(Some(Some(Some(Some(Some(Some(Some(Some("")))))))))
+            )))))))))))))))))
+        ))))))))))))))))))
+    ))))))))))))))))) == Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(
+        Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(
+            Ok(Ok(Ok(Ok(Ok(Ok(Ok("")))))))
+        ))))))))))))))))))))))))))))))
+    ))))))))))))))))))))))));
+    //~^^^^^ ERROR E0308
+
+    let x: Atype<
+      Btype<
+        Ctype<
+          Atype<
+            Btype<
+              Ctype<
+                Atype<
+                  Btype<
+                    Ctype<i32, i32>,
+                    i32
+                  >,
+                  i32
+                >,
+                i32
+              >,
+              i32
+            >,
+            i32
+          >,
+          i32
+        >,
+        i32
+      >,
+      i32
+    > = ();
+    //~^ ERROR E0308
+
+    let _: () = Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(
+        Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(
+            Ok(Ok(Ok(Ok(Ok(Ok(Ok("")))))))
+        ))))))))))))))))))))))))))))))
+    ))))))))))))))))))))))));
+    //~^^^^^ ERROR E0308
+}
diff --git a/src/test/ui/diagnostic-width/long-E0308.stderr b/src/test/ui/diagnostic-width/long-E0308.stderr
new file mode 100644
index 00000000000..487ab23a1c1
--- /dev/null
+++ b/src/test/ui/diagnostic-width/long-E0308.stderr
@@ -0,0 +1,80 @@
+error[E0308]: mismatched types
+  --> $DIR/long-E0308.rs:33:9
+   |
+LL |        let x: Atype<
+   |  _____________-
+LL | |        Btype<
+LL | |          Ctype<
+LL | |            Atype<
+...  |
+LL | |        i32
+LL | |      > = Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok...
+   | | _____-___^
+   | ||_____|
+   |  |     expected due to this
+LL |  |         Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok...
+LL |  |             Ok("")
+LL |  |         ))))))))))))))))))))))))))))))
+LL |  |     ))))))))))))))))))))))))))))));
+   |  |__________________________________^ expected struct `Atype`, found enum `Result`
+   |
+   = note: expected struct `Atype<Btype<..., ...>, ...>`
+           the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308/long-E0308.long-type-hash.txt'
+                found enum `Result<Result<..., ...>, ...>`
+           the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308/long-E0308.long-type-hash.txt'
+
+error[E0308]: mismatched types
+  --> $DIR/long-E0308.rs:46:26
+   |
+LL |       ))))))))))))))))) == Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(O...
+   |  __________________________^
+LL | |         Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(...
+LL | |             Ok(Ok(Ok(Ok(Ok(Ok(Ok("")))))))
+LL | |         ))))))))))))))))))))))))))))))
+LL | |     ))))))))))))))))))))))));
+   | |____________________________^ expected enum `Option`, found enum `Result`
+   |
+   = note: expected enum `Option<Result<..., ...>>`
+           the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308/long-E0308.long-type-hash.txt'
+              found enum `Result<Result<..., ...>, ...>`
+           the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308/long-E0308.long-type-hash.txt'
+
+error[E0308]: mismatched types
+  --> $DIR/long-E0308.rs:77:9
+   |
+LL |       let x: Atype<
+   |  ____________-
+LL | |       Btype<
+LL | |         Ctype<
+LL | |           Atype<
+...  |
+LL | |       i32
+LL | |     > = ();
+   | |     -   ^^ expected struct `Atype`, found `()`
+   | |_____|
+   |       expected due to this
+   |
+   = note: expected struct `Atype<Btype<..., ...>, ...>`
+           the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308/long-E0308.long-type-hash.txt'
+           found unit type `()`
+
+error[E0308]: mismatched types
+  --> $DIR/long-E0308.rs:80:17
+   |
+LL |       let _: () = Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(O...
+   |  ____________--___^
+   | |            |
+   | |            expected due to this
+LL | |         Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(...
+LL | |             Ok(Ok(Ok(Ok(Ok(Ok(Ok("")))))))
+LL | |         ))))))))))))))))))))))))))))))
+LL | |     ))))))))))))))))))))))));
+   | |____________________________^ expected `()`, found enum `Result`
+   |
+   = note: expected unit type `()`
+                   found enum `Result<Result<..., ...>, ...>`
+           the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308/long-E0308.long-type-hash.txt'
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/error-codes/E0275.stderr b/src/test/ui/error-codes/E0275.stderr
index 49a4d984af9..451a683ac8a 100644
--- a/src/test/ui/error-codes/E0275.stderr
+++ b/src/test/ui/error-codes/E0275.stderr
@@ -5,7 +5,7 @@ LL | impl<T> Foo for T where Bar<T>: Foo {}
    |                                 ^^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`E0275`)
-note: required for `Bar<Bar<Bar<Bar<Bar<Bar<...>>>>>>` to implement `Foo`
+note: required for `Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<Bar<...>>>>>>>>>>>>>>>>>>>>>` to implement `Foo`
   --> $DIR/E0275.rs:6:9
    |
 LL | impl<T> Foo for T where Bar<T>: Foo {}
diff --git a/src/test/ui/feature-gates/feature-gate-impl_trait_in_fn_trait_return.stderr b/src/test/ui/feature-gates/feature-gate-impl_trait_in_fn_trait_return.stderr
index c485bc5c3ab..760dcb615c8 100644
--- a/src/test/ui/feature-gates/feature-gate-impl_trait_in_fn_trait_return.stderr
+++ b/src/test/ui/feature-gates/feature-gate-impl_trait_in_fn_trait_return.stderr
@@ -3,12 +3,18 @@ error[E0562]: `impl Trait` only allowed in function and inherent method return t
    |
 LL | fn f() -> impl Fn() -> impl Sized { || () }
    |                        ^^^^^^^^^^
+   |
+   = note: see issue #99697 <https://github.com/rust-lang/rust/issues/99697> for more information
+   = help: add `#![feature(impl_trait_in_fn_trait_return)]` to the crate attributes to enable
 
 error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait return
   --> $DIR/feature-gate-impl_trait_in_fn_trait_return.rs:3:32
    |
 LL | fn g() -> &'static dyn Fn() -> impl Sized { &|| () }
    |                                ^^^^^^^^^^
+   |
+   = note: see issue #99697 <https://github.com/rust-lang/rust/issues/99697> for more information
+   = help: add `#![feature(impl_trait_in_fn_trait_return)]` to the crate attributes to enable
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/issues/issue-20413.stderr b/src/test/ui/issues/issue-20413.stderr
index 91509ceace8..78df445972c 100644
--- a/src/test/ui/issues/issue-20413.stderr
+++ b/src/test/ui/issues/issue-20413.stderr
@@ -14,7 +14,7 @@ LL | impl<T> Foo for T where NoData<T>: Foo {
    |                                    ^^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_20413`)
-note: required for `NoData<NoData<NoData<NoData<NoData<NoData<...>>>>>>` to implement `Foo`
+note: required for `NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<NoData<...>>>>>>>>>>>>>` to implement `Foo`
   --> $DIR/issue-20413.rs:9:9
    |
 LL | impl<T> Foo for T where NoData<T>: Foo {
@@ -30,13 +30,13 @@ LL | impl<T> Bar for T where EvenLessData<T>: Baz {
    |                                          ^^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_20413`)
-note: required for `AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<...>>>>>>` to implement `Bar`
+note: required for `AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<...>>>>>>>` to implement `Bar`
   --> $DIR/issue-20413.rs:28:9
    |
 LL | impl<T> Bar for T where EvenLessData<T>: Baz {
    |         ^^^     ^
    = note: the full type name has been written to '$TEST_BUILD_DIR/issues/issue-20413/issue-20413.long-type-hash.txt'
-note: required for `EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<...>>>>>>` to implement `Baz`
+note: required for `EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<...>>>>>>>` to implement `Baz`
   --> $DIR/issue-20413.rs:35:9
    |
 LL | impl<T> Baz for T where AlmostNoData<T>: Bar {
@@ -52,13 +52,13 @@ LL | impl<T> Baz for T where AlmostNoData<T>: Bar {
    |                                          ^^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_20413`)
-note: required for `EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<...>>>>>>` to implement `Baz`
+note: required for `EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<...>>>>>>>` to implement `Baz`
   --> $DIR/issue-20413.rs:35:9
    |
 LL | impl<T> Baz for T where AlmostNoData<T>: Bar {
    |         ^^^     ^
    = note: the full type name has been written to '$TEST_BUILD_DIR/issues/issue-20413/issue-20413.long-type-hash.txt'
-note: required for `AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<...>>>>>>` to implement `Bar`
+note: required for `AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<EvenLessData<AlmostNoData<...>>>>>>>` to implement `Bar`
   --> $DIR/issue-20413.rs:28:9
    |
 LL | impl<T> Bar for T where EvenLessData<T>: Baz {
diff --git a/src/test/ui/issues/issue-23122-2.stderr b/src/test/ui/issues/issue-23122-2.stderr
index 5828e027b59..1f50b06a0e4 100644
--- a/src/test/ui/issues/issue-23122-2.stderr
+++ b/src/test/ui/issues/issue-23122-2.stderr
@@ -5,7 +5,7 @@ LL |     type Next = <GetNext<T::Next> as Next>::Next;
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_23122_2`)
-note: required for `GetNext<<<<<<... as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next>` to implement `Next`
+note: required for `GetNext<<<<<<<... as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next as Next>::Next>` to implement `Next`
   --> $DIR/issue-23122-2.rs:10:15
    |
 LL | impl<T: Next> Next for GetNext<T> {
diff --git a/src/test/ui/recursion/issue-83150.stderr b/src/test/ui/recursion/issue-83150.stderr
index 4d00a708313..dde8ad1b6b3 100644
--- a/src/test/ui/recursion/issue-83150.stderr
+++ b/src/test/ui/recursion/issue-83150.stderr
@@ -12,7 +12,7 @@ LL |     func(&mut iter.map(|x| x + 1))
 error[E0275]: overflow evaluating the requirement `Map<&mut Map<&mut Map<&mut Map<..., ...>, ...>, ...>, ...>: Iterator`
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`issue_83150`)
-   = note: required for `&mut Map<&mut Map<&mut Map<..., ...>, ...>, ...>` to implement `Iterator`
+   = note: required for `&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<&mut Map<..., ...>, ...>, ...>, ...>, ...>, ...>, ...>` to implement `Iterator`
    = note: the full type name has been written to '$TEST_BUILD_DIR/recursion/issue-83150/issue-83150.long-type-hash.txt'
 
 error: aborting due to previous error; 1 warning emitted
diff --git a/src/test/ui/regions/issue-102374.rs b/src/test/ui/regions/issue-102374.rs
index e0a1164211a..fd71248d9cb 100644
--- a/src/test/ui/regions/issue-102374.rs
+++ b/src/test/ui/regions/issue-102374.rs
@@ -1,3 +1,4 @@
+// normalize-stderr-test: "long-type-\d+" -> "long-type-hash"
 use std::cell::Cell;
 
 #[rustfmt::skip]
diff --git a/src/test/ui/regions/issue-102374.stderr b/src/test/ui/regions/issue-102374.stderr
index 31b855c36be..157850693ab 100644
--- a/src/test/ui/regions/issue-102374.stderr
+++ b/src/test/ui/regions/issue-102374.stderr
@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/issue-102374.rs:16:5
+  --> $DIR/issue-102374.rs:17:5
    |
 LL | ) -> i32 {
    |      --- expected `i32` because of return type
@@ -7,7 +7,8 @@ LL |     f
    |     ^ expected `i32`, found fn pointer
    |
    = note:    expected type `i32`
-           found fn pointer `for<'z1, 'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, 'i, 'j, 'k, 'l, 'm, 'n, 'o, 'p, 'q, 'r, 's, 't, 'u, 'v, 'w, 'x, 'y, 'z, 'z0> fn(Cell<(&'z1 i32, &'a i32, &'b i32, &'c i32, &'d i32, &'e i32, &'f i32, &'g i32, &'h i32, &'i i32, &'j i32, &'k i32, &'l i32, &'m i32, &'n i32, &'o i32, &'p i32, &'q i32, &'r i32, &'s i32, &'t i32, &'u i32, &'v i32, &'w i32, &'x i32, &'y i32, &'z i32, &'z0 i32)>)`
+           found fn pointer `for<'z1, 'a, 'b, 'c, 'd, 'e, 'f, 'g, 'h, 'i, 'j, 'k, 'l, 'm, 'n, 'o, 'p, 'q, 'r, 's, 't, 'u, 'v, 'w, 'x, 'y, 'z, 'z0> fn(Cell<...>)`
+           the full type name has been written to '$TEST_BUILD_DIR/regions/issue-102374/issue-102374.long-type-hash.txt'
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/traits/issue-91949-hangs-on-recursion.stderr b/src/test/ui/traits/issue-91949-hangs-on-recursion.stderr
index a74d2524996..1f18c5daf66 100644
--- a/src/test/ui/traits/issue-91949-hangs-on-recursion.stderr
+++ b/src/test/ui/traits/issue-91949-hangs-on-recursion.stderr
@@ -17,7 +17,7 @@ error[E0275]: overflow evaluating the requirement `(): Sized`
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "512"]` attribute to your crate (`issue_91949_hangs_on_recursion`)
    = note: required for `std::iter::Empty<()>` to implement `Iterator`
    = note: 171 redundant requirements hidden
-   = note: required for `IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<..., ...>>, ...>>` to implement `Iterator`
+   = note: required for `IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<IteratorOfWrapped<(), Map<..., ...>>, ...>>, ...>>` to implement `Iterator`
    = note: the full type name has been written to '$TEST_BUILD_DIR/traits/issue-91949-hangs-on-recursion/issue-91949-hangs-on-recursion.long-type-hash.txt'
 
 error: aborting due to previous error; 1 warning emitted
diff --git a/src/tools/miri/src/borrow_tracker/mod.rs b/src/tools/miri/src/borrow_tracker/mod.rs
index 10e6e252e94..f896a337f42 100644
--- a/src/tools/miri/src/borrow_tracker/mod.rs
+++ b/src/tools/miri/src/borrow_tracker/mod.rs
@@ -11,7 +11,6 @@ use rustc_target::abi::Size;
 
 use crate::*;
 pub mod stacked_borrows;
-use stacked_borrows::diagnostics::RetagCause;
 
 pub type CallId = NonZeroU64;
 
@@ -265,11 +264,19 @@ impl GlobalStateInner {
 
 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriInterpCx<'mir, 'tcx> {}
 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
-    fn retag(&mut self, kind: RetagKind, place: &PlaceTy<'tcx, Provenance>) -> InterpResult<'tcx> {
+    fn retag_ptr_value(&mut self, kind: RetagKind, val: &ImmTy<'tcx, Provenance>) -> InterpResult<'tcx, ImmTy<'tcx, Provenance>> {
         let this = self.eval_context_mut();
         let method = this.machine.borrow_tracker.as_ref().unwrap().borrow().borrow_tracker_method;
         match method {
-            BorrowTrackerMethod::StackedBorrows => this.sb_retag(kind, place),
+            BorrowTrackerMethod::StackedBorrows => this.sb_retag_ptr_value(kind, val),
+        }
+    }
+
+    fn retag_place_contents(&mut self, kind: RetagKind, place: &PlaceTy<'tcx, Provenance>) -> InterpResult<'tcx> {
+        let this = self.eval_context_mut();
+        let method = this.machine.borrow_tracker.as_ref().unwrap().borrow().borrow_tracker_method;
+        match method {
+            BorrowTrackerMethod::StackedBorrows => this.sb_retag_place_contents(kind, place),
         }
     }
 
diff --git a/src/tools/miri/src/borrow_tracker/stacked_borrows/diagnostics.rs b/src/tools/miri/src/borrow_tracker/stacked_borrows/diagnostics.rs
index 9a7b38b13a3..24b3489e0d1 100644
--- a/src/tools/miri/src/borrow_tracker/stacked_borrows/diagnostics.rs
+++ b/src/tools/miri/src/borrow_tracker/stacked_borrows/diagnostics.rs
@@ -459,10 +459,10 @@ impl<'history, 'ecx, 'mir, 'tcx> DiagnosticCx<'history, 'ecx, 'mir, 'tcx> {
             Operation::Dealloc(_) => format!(" due to deallocation"),
             Operation::Access(AccessOp { kind, tag, .. }) =>
                 format!(" due to {kind:?} access for {tag:?}"),
-            Operation::Retag(RetagOp { orig_tag, permission, .. }) => {
+            Operation::Retag(RetagOp { orig_tag, permission, new_tag, .. }) => {
                 let permission = permission
                     .expect("start_grant should set the current permission before popping a tag");
-                format!(" due to {permission:?} retag from {orig_tag:?}")
+                format!(" due to {permission:?} retag from {orig_tag:?} (that retag created {new_tag:?})")
             }
         };
 
diff --git a/src/tools/miri/src/borrow_tracker/stacked_borrows/mod.rs b/src/tools/miri/src/borrow_tracker/stacked_borrows/mod.rs
index bcac873251f..ffbc0086402 100644
--- a/src/tools/miri/src/borrow_tracker/stacked_borrows/mod.rs
+++ b/src/tools/miri/src/borrow_tracker/stacked_borrows/mod.rs
@@ -1,9 +1,13 @@
 //! Implements "Stacked Borrows".  See <https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md>
 //! for further information.
 
+pub mod diagnostics;
+mod item;
+mod stack;
+
 use log::trace;
 use std::cmp;
-use std::fmt::{self, Write};
+use std::fmt::Write;
 
 use rustc_data_structures::fx::FxHashSet;
 use rustc_middle::mir::{Mutability, RetagKind};
@@ -15,15 +19,13 @@ use rustc_target::abi::{Abi, Size};
 
 use crate::borrow_tracker::{
     stacked_borrows::diagnostics::{AllocHistory, DiagnosticCx, DiagnosticCxBuilder, TagHistory},
-    AccessKind, GlobalStateInner, ProtectorKind, RetagCause, RetagFields,
+    AccessKind, GlobalStateInner, ProtectorKind, RetagFields,
 };
 use crate::*;
 
-mod item;
+use diagnostics::RetagCause;
 pub use item::{Item, Permission};
-mod stack;
 pub use stack::Stack;
-pub mod diagnostics;
 
 pub type AllocState = Stacks;
 
@@ -40,30 +42,104 @@ pub struct Stacks {
     modified_since_last_gc: bool,
 }
 
-/// Indicates which kind of reference is being created.
-/// Used by high-level `reborrow` to compute which permissions to grant to the
-/// new pointer.
-#[derive(Copy, Clone, Hash, PartialEq, Eq)]
-enum RefKind {
-    /// `Box`.
-    Box,
-    /// `&mut`.
-    Unique { two_phase: bool },
-    /// `&` with or without interior mutability.
-    Shared,
-    /// `*mut`/`*const` (raw pointers).
-    Raw { mutable: bool },
+/// Indicates which permissions to grant to the retagged pointer.
+#[derive(Clone, Debug)]
+enum NewPermission {
+    Uniform {
+        perm: Permission,
+        access: Option<AccessKind>,
+        protector: Option<ProtectorKind>,
+    },
+    FreezeSensitive {
+        freeze_perm: Permission,
+        freeze_access: Option<AccessKind>,
+        freeze_protector: Option<ProtectorKind>,
+        nonfreeze_perm: Permission,
+        nonfreeze_access: Option<AccessKind>,
+        // nonfreeze_protector must always be None
+    },
 }
 
-impl fmt::Display for RefKind {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+impl NewPermission {
+    /// A key function: determine the permissions to grant at a retag for the given kind of
+    /// reference/pointer.
+    fn from_ref_ty<'tcx>(
+        ty: ty::Ty<'tcx>,
+        kind: RetagKind,
+        cx: &crate::MiriInterpCx<'_, 'tcx>,
+    ) -> Self {
+        let protector = (kind == RetagKind::FnEntry).then_some(ProtectorKind::StrongProtector);
+        match ty.kind() {
+            ty::Ref(_, pointee, Mutability::Mut) => {
+                if kind == RetagKind::TwoPhase {
+                    // We mostly just give up on 2phase-borrows, and treat these exactly like raw pointers.
+                    assert!(protector.is_none()); // RetagKind can't be both FnEntry and TwoPhase.
+                    NewPermission::Uniform {
+                        perm: Permission::SharedReadWrite,
+                        access: None,
+                        protector: None,
+                    }
+                } else if pointee.is_unpin(*cx.tcx, cx.param_env()) {
+                    // A regular full mutable reference.
+                    NewPermission::Uniform {
+                        perm: Permission::Unique,
+                        access: Some(AccessKind::Write),
+                        protector,
+                    }
+                } else {
+                    NewPermission::Uniform {
+                        perm: Permission::SharedReadWrite,
+                        // FIXME: We emit `dereferenceable` for `!Unpin` mutable references, so we
+                        // should do fake accesses here. But then we run into
+                        // <https://github.com/rust-lang/unsafe-code-guidelines/issues/381>, so for now
+                        // we don't do that.
+                        access: None,
+                        protector,
+                    }
+                }
+            }
+            ty::RawPtr(ty::TypeAndMut { mutbl: Mutability::Mut, .. }) => {
+                assert!(protector.is_none()); // RetagKind can't be both FnEntry and Raw.
+                // Mutable raw pointer. No access, not protected.
+                NewPermission::Uniform {
+                    perm: Permission::SharedReadWrite,
+                    access: None,
+                    protector: None,
+                }
+            }
+            ty::Ref(_, _pointee, Mutability::Not) => {
+                NewPermission::FreezeSensitive {
+                    freeze_perm: Permission::SharedReadOnly,
+                    freeze_access: Some(AccessKind::Read),
+                    freeze_protector: protector,
+                    nonfreeze_perm: Permission::SharedReadWrite,
+                    // Inside UnsafeCell, this does *not* count as an access, as there
+                    // might actually be mutable references further up the stack that
+                    // we have to keep alive.
+                    nonfreeze_access: None,
+                    // We do not protect inside UnsafeCell.
+                    // This fixes https://github.com/rust-lang/rust/issues/55005.
+                }
+            }
+            ty::RawPtr(ty::TypeAndMut { mutbl: Mutability::Not, .. }) => {
+                assert!(protector.is_none()); // RetagKind can't be both FnEntry and Raw.
+                // `*const T`, when freshly created, are read-only in the frozen part.
+                NewPermission::FreezeSensitive {
+                    freeze_perm: Permission::SharedReadOnly,
+                    freeze_access: Some(AccessKind::Read),
+                    freeze_protector: None,
+                    nonfreeze_perm: Permission::SharedReadWrite,
+                    nonfreeze_access: None,
+                }
+            }
+            _ => unreachable!(),
+        }
+    }
+
+    fn protector(&self) -> Option<ProtectorKind> {
         match self {
-            RefKind::Box => write!(f, "Box"),
-            RefKind::Unique { two_phase: false } => write!(f, "unique reference"),
-            RefKind::Unique { two_phase: true } => write!(f, "unique reference (two-phase)"),
-            RefKind::Shared => write!(f, "shared reference"),
-            RefKind::Raw { mutable: true } => write!(f, "raw (mutable) pointer"),
-            RefKind::Raw { mutable: false } => write!(f, "raw (constant) pointer"),
+            NewPermission::Uniform { protector, .. } => *protector,
+            NewPermission::FreezeSensitive { freeze_protector, .. } => *freeze_protector,
         }
     }
 }
@@ -518,10 +594,9 @@ trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'
         &mut self,
         place: &MPlaceTy<'tcx, Provenance>,
         size: Size,
-        kind: RefKind,
-        retag_cause: RetagCause, // What caused this retag, for diagnostics only
+        new_perm: NewPermission,
         new_tag: BorTag,
-        protect: Option<ProtectorKind>,
+        retag_cause: RetagCause, // What caused this retag, for diagnostics only
     ) -> InterpResult<'tcx, Option<AllocId>> {
         let this = self.eval_context_mut();
 
@@ -532,20 +607,16 @@ trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'
             let global = this.machine.borrow_tracker.as_ref().unwrap().borrow();
             let ty = place.layout.ty;
             if global.tracked_pointer_tags.contains(&new_tag) {
-                let mut kind_str = format!("{kind}");
-                match kind {
-                    RefKind::Unique { two_phase: false }
-                        if !ty.is_unpin(*this.tcx, this.param_env()) =>
-                    {
-                        write!(kind_str, " (!Unpin pointee type {ty})").unwrap()
-                    },
-                    RefKind::Shared
-                        if !ty.is_freeze(*this.tcx, this.param_env()) =>
-                    {
-                        write!(kind_str, " (!Freeze pointee type {ty})").unwrap()
-                    },
-                    _ => write!(kind_str, " (pointee type {ty})").unwrap(),
-                };
+                let mut kind_str = String::new();
+                match new_perm {
+                    NewPermission::Uniform { perm, .. } =>
+                        write!(kind_str, "{perm:?} permission").unwrap(),
+                    NewPermission::FreezeSensitive { freeze_perm, .. } if ty.is_freeze(*this.tcx, this.param_env()) =>
+                        write!(kind_str, "{freeze_perm:?} permission").unwrap(),
+                    NewPermission::FreezeSensitive { freeze_perm, nonfreeze_perm, .. }  =>
+                        write!(kind_str, "{freeze_perm:?}/{nonfreeze_perm:?} permission for frozen/non-frozen parts").unwrap(),
+                }
+                write!(kind_str, " (pointee type {ty})").unwrap();
                 this.emit_diagnostic(NonHaltingDiagnostic::CreatedPointerTag(
                     new_tag.inner(),
                     Some(kind_str),
@@ -579,7 +650,7 @@ trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'
                     );
                     let mut dcx = dcx.build(&mut stacked_borrows.history, base_offset);
                     dcx.log_creation();
-                    if protect.is_some() {
+                    if new_perm.protector().is_some() {
                         dcx.log_protector();
                     }
                 },
@@ -592,8 +663,7 @@ trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'
 
         if size == Size::ZERO {
             trace!(
-                "reborrow of size 0: {} reference {:?} derived from {:?} (pointee {})",
-                kind,
+                "reborrow of size 0: reference {:?} derived from {:?} (pointee {})",
                 new_tag,
                 place.ptr,
                 place.layout.ty,
@@ -630,8 +700,7 @@ trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'
         }
 
         trace!(
-            "reborrow: {} reference {:?} derived from {:?} (pointee {}): {:?}, size {}",
-            kind,
+            "reborrow: reference {:?} derived from {:?} (pointee {}): {:?}, size {}",
             new_tag,
             orig_tag,
             place.layout.ty,
@@ -639,7 +708,7 @@ trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'
             size.bytes()
         );
 
-        if let Some(protect) = protect {
+        if let Some(protect) = new_perm.protector() {
             // See comment in `Stack::item_invalidated` for why we store the tag twice.
             this.frame_mut().extra.borrow_tracker.as_mut().unwrap().protected_tags.push(new_tag);
             this.machine
@@ -651,30 +720,45 @@ trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'
                 .insert(new_tag, protect);
         }
 
-        // Update the stacks.
-        // Make sure that raw pointers and mutable shared references are reborrowed "weak":
-        // There could be existing unique pointers reborrowed from them that should remain valid!
-        let (perm, access) = match kind {
-            RefKind::Unique { two_phase } => {
-                // Permission is Unique only if the type is `Unpin` and this is not twophase
-                if !two_phase && place.layout.ty.is_unpin(*this.tcx, this.param_env()) {
-                    (Permission::Unique, Some(AccessKind::Write))
-                } else {
-                    // FIXME: We emit `dereferenceable` for `!Unpin` mutable references, so we
-                    // should do fake accesses here. But then we run into
-                    // <https://github.com/rust-lang/unsafe-code-guidelines/issues/381>, so for now
-                    // we don't do that.
-                    (Permission::SharedReadWrite, None)
+        // Update the stacks, according to the new permission information we are given.
+        match new_perm {
+            NewPermission::Uniform { perm, access, protector } => {
+                assert!(perm != Permission::SharedReadOnly);
+                // Here we can avoid `borrow()` calls because we have mutable references.
+                // Note that this asserts that the allocation is mutable -- but since we are creating a
+                // mutable pointer, that seems reasonable.
+                let (alloc_extra, machine) = this.get_alloc_extra_mut(alloc_id)?;
+                let stacked_borrows = alloc_extra.borrow_tracker_sb_mut().get_mut();
+                let item = Item::new(new_tag, perm, protector.is_some());
+                let range = alloc_range(base_offset, size);
+                let global = machine.borrow_tracker.as_ref().unwrap().borrow();
+                let dcx = DiagnosticCxBuilder::retag(
+                    machine,
+                    retag_cause,
+                    new_tag,
+                    orig_tag,
+                    alloc_range(base_offset, size),
+                );
+                stacked_borrows.for_each(range, dcx, |stack, dcx, exposed_tags| {
+                    stack.grant(orig_tag, item, access, &global, dcx, exposed_tags)
+                })?;
+                drop(global);
+                if let Some(access) = access {
+                    assert_eq!(access, AccessKind::Write);
+                    // Make sure the data race model also knows about this.
+                    if let Some(data_race) = alloc_extra.data_race.as_mut() {
+                        data_race.write(alloc_id, range, machine)?;
+                    }
                 }
             }
-            RefKind::Box => (Permission::Unique, Some(AccessKind::Write)),
-            RefKind::Raw { mutable: true } => {
-                // Creating a raw ptr does not count as an access
-                (Permission::SharedReadWrite, None)
-            }
-            RefKind::Shared | RefKind::Raw { mutable: false } => {
-                // Shared references and *const are a whole different kind of game, the
-                // permission is not uniform across the entire range!
+            NewPermission::FreezeSensitive {
+                freeze_perm,
+                freeze_access,
+                freeze_protector,
+                nonfreeze_perm,
+                nonfreeze_access,
+            } => {
+                // The permission is not uniform across the entire range!
                 // We need a frozen-sensitive reborrow.
                 // We have to use shared references to alloc/memory_extra here since
                 // `visit_freeze_sensitive` needs to access the global state.
@@ -684,22 +768,12 @@ trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'
                     // Adjust range.
                     range.start += base_offset;
                     // We are only ever `SharedReadOnly` inside the frozen bits.
-                    let (perm, access) = if frozen {
-                        (Permission::SharedReadOnly, Some(AccessKind::Read))
-                    } else {
-                        // Inside UnsafeCell, this does *not* count as an access, as there
-                        // might actually be mutable references further up the stack that
-                        // we have to keep alive.
-                        (Permission::SharedReadWrite, None)
-                    };
-                    let protected = if frozen {
-                        protect.is_some()
+                    let (perm, access, protector) = if frozen {
+                        (freeze_perm, freeze_access, freeze_protector)
                     } else {
-                        // We do not protect inside UnsafeCell.
-                        // This fixes https://github.com/rust-lang/rust/issues/55005.
-                        false
+                        (nonfreeze_perm, nonfreeze_access, None)
                     };
-                    let item = Item::new(new_tag, perm, protected);
+                    let item = Item::new(new_tag, perm, protector.is_some());
                     let global = this.machine.borrow_tracker.as_ref().unwrap().borrow();
                     let dcx = DiagnosticCxBuilder::retag(
                         &this.machine,
@@ -721,34 +795,6 @@ trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'
                     }
                     Ok(())
                 })?;
-                return Ok(Some(alloc_id));
-            }
-        };
-
-        // Here we can avoid `borrow()` calls because we have mutable references.
-        // Note that this asserts that the allocation is mutable -- but since we are creating a
-        // mutable pointer, that seems reasonable.
-        let (alloc_extra, machine) = this.get_alloc_extra_mut(alloc_id)?;
-        let stacked_borrows = alloc_extra.borrow_tracker_sb_mut().get_mut();
-        let item = Item::new(new_tag, perm, protect.is_some());
-        let range = alloc_range(base_offset, size);
-        let global = machine.borrow_tracker.as_ref().unwrap().borrow();
-        let dcx = DiagnosticCxBuilder::retag(
-            machine,
-            retag_cause,
-            new_tag,
-            orig_tag,
-            alloc_range(base_offset, size),
-        );
-        stacked_borrows.for_each(range, dcx, |stack, dcx, exposed_tags| {
-            stack.grant(orig_tag, item, access, &global, dcx, exposed_tags)
-        })?;
-        drop(global);
-        if let Some(access) = access {
-            assert_eq!(access, AccessKind::Write);
-            // Make sure the data race model also knows about this.
-            if let Some(data_race) = alloc_extra.data_race.as_mut() {
-                data_race.write(alloc_id, range, machine)?;
             }
         }
 
@@ -760,9 +806,8 @@ trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'
     fn sb_retag_reference(
         &mut self,
         val: &ImmTy<'tcx, Provenance>,
-        kind: RefKind,
-        retag_cause: RetagCause, // What caused this retag, for diagnostics only
-        protect: Option<ProtectorKind>,
+        new_perm: NewPermission,
+        cause: RetagCause, // What caused this retag, for diagnostics only
     ) -> InterpResult<'tcx, ImmTy<'tcx, Provenance>> {
         let this = self.eval_context_mut();
         // We want a place for where the ptr *points to*, so we get one.
@@ -780,7 +825,7 @@ trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'
         let new_tag = this.machine.borrow_tracker.as_mut().unwrap().get_mut().new_ptr();
 
         // Reborrow.
-        let alloc_id = this.sb_reborrow(&place, size, kind, retag_cause, new_tag, protect)?;
+        let alloc_id = this.sb_reborrow(&place, size, new_perm, new_tag, cause)?;
 
         // Adjust pointer.
         let new_place = place.map_provenance(|p| {
@@ -807,7 +852,22 @@ trait EvalContextPrivExt<'mir: 'ecx, 'tcx: 'mir, 'ecx>: crate::MiriInterpCxExt<'
 
 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriInterpCx<'mir, 'tcx> {}
 pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
-    fn sb_retag(
+    fn sb_retag_ptr_value(
+        &mut self,
+        kind: RetagKind,
+        val: &ImmTy<'tcx, Provenance>,
+    ) -> InterpResult<'tcx, ImmTy<'tcx, Provenance>> {
+        let this = self.eval_context_mut();
+        let new_perm = NewPermission::from_ref_ty(val.layout.ty, kind, this);
+        let retag_cause = match kind {
+            RetagKind::TwoPhase { .. } => RetagCause::TwoPhase,
+            RetagKind::FnEntry => unreachable!(),
+            RetagKind::Raw | RetagKind::Default => RetagCause::Normal,
+        };
+        this.sb_retag_reference(&val, new_perm, retag_cause)
+    }
+
+    fn sb_retag_place_contents(
         &mut self,
         kind: RetagKind,
         place: &PlaceTy<'tcx, Provenance>,
@@ -815,9 +875,9 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
         let this = self.eval_context_mut();
         let retag_fields = this.machine.borrow_tracker.as_mut().unwrap().get_mut().retag_fields;
         let retag_cause = match kind {
-            RetagKind::TwoPhase { .. } => RetagCause::TwoPhase,
+            RetagKind::Raw | RetagKind::TwoPhase { .. } => unreachable!(), // these can only happen in `retag_ptr_value`
             RetagKind::FnEntry => RetagCause::FnEntry,
-            RetagKind::Raw | RetagKind::Default => RetagCause::Normal,
+            RetagKind::Default => RetagCause::Normal,
         };
         let mut visitor = RetagVisitor { ecx: this, kind, retag_cause, retag_fields };
         return visitor.visit_value(place);
@@ -831,15 +891,14 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
         }
         impl<'ecx, 'mir, 'tcx> RetagVisitor<'ecx, 'mir, 'tcx> {
             #[inline(always)] // yes this helps in our benchmarks
-            fn retag_place(
+            fn retag_ptr_inplace(
                 &mut self,
                 place: &PlaceTy<'tcx, Provenance>,
-                ref_kind: RefKind,
+                new_perm: NewPermission,
                 retag_cause: RetagCause,
-                protector: Option<ProtectorKind>,
             ) -> InterpResult<'tcx> {
                 let val = self.ecx.read_immediate(&self.ecx.place_to_op(place)?)?;
-                let val = self.ecx.sb_retag_reference(&val, ref_kind, retag_cause, protector)?;
+                let val = self.ecx.sb_retag_reference(&val, new_perm, retag_cause)?;
                 self.ecx.write_immediate(*val, place)?;
                 Ok(())
             }
@@ -856,13 +915,13 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
 
             fn visit_box(&mut self, place: &PlaceTy<'tcx, Provenance>) -> InterpResult<'tcx> {
                 // Boxes get a weak protectors, since they may be deallocated.
-                self.retag_place(
-                    place,
-                    RefKind::Box,
-                    self.retag_cause,
-                    /*protector*/
-                    (self.kind == RetagKind::FnEntry).then_some(ProtectorKind::WeakProtector),
-                )
+                let new_perm = NewPermission::Uniform {
+                    perm: Permission::Unique,
+                    access: Some(AccessKind::Write),
+                    protector: (self.kind == RetagKind::FnEntry)
+                        .then_some(ProtectorKind::WeakProtector),
+                };
+                self.retag_ptr_inplace(place, new_perm, self.retag_cause)
             }
 
             fn visit_value(&mut self, place: &PlaceTy<'tcx, Provenance>) -> InterpResult<'tcx> {
@@ -876,36 +935,16 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
 
                 // Check the type of this value to see what to do with it (retag, or recurse).
                 match place.layout.ty.kind() {
-                    ty::Ref(_, _, mutbl) => {
-                        let ref_kind = match mutbl {
-                            Mutability::Mut =>
-                                RefKind::Unique { two_phase: self.kind == RetagKind::TwoPhase },
-                            Mutability::Not => RefKind::Shared,
-                        };
-                        self.retag_place(
-                            place,
-                            ref_kind,
-                            self.retag_cause,
-                            /*protector*/
-                            (self.kind == RetagKind::FnEntry)
-                                .then_some(ProtectorKind::StrongProtector),
-                        )?;
+                    ty::Ref(..) => {
+                        let new_perm =
+                            NewPermission::from_ref_ty(place.layout.ty, self.kind, self.ecx);
+                        self.retag_ptr_inplace(place, new_perm, self.retag_cause)?;
                     }
-                    ty::RawPtr(tym) => {
-                        // We definitely do *not* want to recurse into raw pointers -- wide raw
-                        // pointers have fields, and for dyn Trait pointees those can have reference
-                        // type!
-                        if self.kind == RetagKind::Raw {
-                            // Raw pointers need to be enabled.
-                            self.retag_place(
-                                place,
-                                RefKind::Raw { mutable: tym.mutbl == Mutability::Mut },
-                                self.retag_cause,
-                                /*protector*/ None,
-                            )?;
-                        }
+                    ty::RawPtr(..) => {
+                        // We do *not* want to recurse into raw pointers -- wide raw pointers have
+                        // fields, and for dyn Trait pointees those can have reference type!
                     }
-                    _ if place.layout.ty.ty_adt_def().is_some_and(|adt| adt.is_box()) => {
+                    ty::Adt(adt, _) if adt.is_box() => {
                         // Recurse for boxes, they require some tricky handling and will end up in `visit_box` above.
                         // (Yes this means we technically also recursively retag the allocator itself
                         // even if field retagging is not enabled. *shrug*)
@@ -953,12 +992,12 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
         let ptr_layout = this.layout_of(this.tcx.mk_mut_ptr(return_place.layout.ty))?;
         let val = ImmTy::from_immediate(return_place.to_ref(this), ptr_layout);
         // Reborrow it. With protection! That is part of the point.
-        let val = this.sb_retag_reference(
-            &val,
-            RefKind::Unique { two_phase: false },
-            RetagCause::FnReturn,
-            /*protector*/ Some(ProtectorKind::StrongProtector),
-        )?;
+        let new_perm = NewPermission::Uniform {
+            perm: Permission::Unique,
+            access: Some(AccessKind::Write),
+            protector: Some(ProtectorKind::StrongProtector),
+        };
+        let val = this.sb_retag_reference(&val, new_perm, RetagCause::FnReturn)?;
         // And use reborrowed pointer for return place.
         let return_place = this.ref_to_mplace(&val)?;
         this.frame_mut().return_place = return_place.into();
diff --git a/src/tools/miri/src/diagnostics.rs b/src/tools/miri/src/diagnostics.rs
index 074fa032dcc..d0fb9f9b0b5 100644
--- a/src/tools/miri/src/diagnostics.rs
+++ b/src/tools/miri/src/diagnostics.rs
@@ -63,9 +63,9 @@ impl MachineStopType for TerminationInfo {}
 
 /// Miri specific diagnostics
 pub enum NonHaltingDiagnostic {
-    /// (new_tag, new_kind, (alloc_id, base_offset, orig_tag))
+    /// (new_tag, new_perm, (alloc_id, base_offset, orig_tag))
     ///
-    /// new_kind is `None` for base tags.
+    /// new_perm is `None` for base tags.
     CreatedPointerTag(NonZeroU64, Option<String>, Option<(AllocId, AllocRange, ProvenanceExtra)>),
     /// This `Item` was popped from the borrow stack. The string explains the reason.
     PoppedPointerTag(Item, String),
@@ -393,10 +393,10 @@ impl<'mir, 'tcx> MiriMachine<'mir, 'tcx> {
 
         let msg = match &e {
             CreatedPointerTag(tag, None, _) => format!("created base tag {tag:?}"),
-            CreatedPointerTag(tag, Some(kind), None) => format!("created {tag:?} for {kind}"),
-            CreatedPointerTag(tag, Some(kind), Some((alloc_id, range, orig_tag))) =>
+            CreatedPointerTag(tag, Some(perm), None) => format!("created {tag:?} with {perm} derived from unknown tag"),
+            CreatedPointerTag(tag, Some(perm), Some((alloc_id, range, orig_tag))) =>
                 format!(
-                    "created tag {tag:?} for {kind} at {alloc_id:?}{range:?} derived from {orig_tag:?}"
+                    "created tag {tag:?} with {perm} at {alloc_id:?}{range:?} derived from {orig_tag:?}"
                 ),
             PoppedPointerTag(item, cause) => format!("popped tracked tag for item {item:?}{cause}"),
             CreatedCallId(id) => format!("function call with id {id}"),
diff --git a/src/tools/miri/src/machine.rs b/src/tools/miri/src/machine.rs
index c110229c985..e5b1eb2e487 100644
--- a/src/tools/miri/src/machine.rs
+++ b/src/tools/miri/src/machine.rs
@@ -967,8 +967,9 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
         ptr: Pointer<Self::Provenance>,
     ) -> InterpResult<'tcx> {
         match ptr.provenance {
-            Provenance::Concrete { alloc_id, tag } =>
-                intptrcast::GlobalStateInner::expose_ptr(ecx, alloc_id, tag),
+            Provenance::Concrete { alloc_id, tag } => {
+                intptrcast::GlobalStateInner::expose_ptr(ecx, alloc_id, tag)
+            }
             Provenance::Wildcard => {
                 // No need to do anything for wildcard pointers as
                 // their provenances have already been previously exposed.
@@ -1055,13 +1056,26 @@ impl<'mir, 'tcx> Machine<'mir, 'tcx> for MiriMachine<'mir, 'tcx> {
     }
 
     #[inline(always)]
-    fn retag(
+    fn retag_ptr_value(
+        ecx: &mut InterpCx<'mir, 'tcx, Self>,
+        kind: mir::RetagKind,
+        val: &ImmTy<'tcx, Provenance>,
+    ) -> InterpResult<'tcx, ImmTy<'tcx, Provenance>> {
+        if ecx.machine.borrow_tracker.is_some() {
+            ecx.retag_ptr_value(kind, val)
+        } else {
+            Ok(val.clone())
+        }
+    }
+
+    #[inline(always)]
+    fn retag_place_contents(
         ecx: &mut InterpCx<'mir, 'tcx, Self>,
         kind: mir::RetagKind,
         place: &PlaceTy<'tcx, Provenance>,
     ) -> InterpResult<'tcx> {
         if ecx.machine.borrow_tracker.is_some() {
-            ecx.retag(kind, place)?;
+            ecx.retag_place_contents(kind, place)?;
         }
         Ok(())
     }