Merge from rustc

289 files changed, 3993 insertions, 2424 deletions

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0bce8389d8e..566ae223500 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -234,8 +234,8 @@ jobs:
           fi
           exit ${STATUS}
         env:
-          AWS_ACCESS_KEY_ID: ${{ env.CACHES_AWS_ACCESS_KEY_ID }}
-          AWS_SECRET_ACCESS_KEY: ${{ secrets[format('AWS_SECRET_ACCESS_KEY_{0}', env.CACHES_AWS_ACCESS_KEY_ID)] }}
+          AWS_ACCESS_KEY_ID: ${{ (github.repository == 'rust-lang/rust' && secrets.CACHES_AWS_ACCESS_KEY_ID) || env.CACHES_AWS_ACCESS_KEY_ID }}
+          AWS_SECRET_ACCESS_KEY: ${{ (github.repository == 'rust-lang/rust' && secrets.CACHES_AWS_SECRET_ACCESS_KEY) || secrets[format('AWS_SECRET_ACCESS_KEY_{0}', env.CACHES_AWS_ACCESS_KEY_ID)] }}
 
       - name: create github artifacts
         run: src/ci/scripts/create-doc-artifacts.sh
@@ -257,8 +257,8 @@ jobs:
       - name: upload artifacts to S3
         run: src/ci/scripts/upload-artifacts.sh
         env:
-          AWS_ACCESS_KEY_ID: ${{ env.ARTIFACTS_AWS_ACCESS_KEY_ID }}
-          AWS_SECRET_ACCESS_KEY: ${{ secrets[format('AWS_SECRET_ACCESS_KEY_{0}', env.ARTIFACTS_AWS_ACCESS_KEY_ID)] }}
+          AWS_ACCESS_KEY_ID: ${{ (github.repository == 'rust-lang/rust' && secrets.ARTIFACTS_AWS_ACCESS_KEY_ID) || env.ARTIFACTS_AWS_ACCESS_KEY_ID }}
+          AWS_SECRET_ACCESS_KEY: ${{ (github.repository == 'rust-lang/rust' && secrets.ARTIFACTS_AWS_SECRET_ACCESS_KEY) || secrets[format('AWS_SECRET_ACCESS_KEY_{0}', env.ARTIFACTS_AWS_ACCESS_KEY_ID)] }}
         # Adding a condition on DEPLOY=1 or DEPLOY_ALT=1 is not needed as all deploy
         # builders *should* have the AWS credentials available. Still, explicitly
         # adding the condition is helpful as this way CI will not silently skip
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index e155e253784..aadc7c48ea8 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -5,7 +5,7 @@ and we appreciate all of them.
 
 The best way to get started is by asking for help in the [#new
 members](https://rust-lang.zulipchat.com/#narrow/stream/122652-new-members)
-Zulip stream. We have lots of docs below of how to get started on your own, but
+Zulip stream. We have a lot of documentation below on how to get started on your own, but
 the Zulip stream is the best place to *ask* for help.
 
 Documentation for contributing to the compiler or tooling is located in the [Guide to Rustc
@@ -14,7 +14,7 @@ standard library in the [Standard library developers Guide][std-dev-guide], comm
 
 ## Making changes to subtrees and submodules
 
-For submodules, changes need to be made against the repository corresponding the
+For submodules, changes need to be made against the repository corresponding to the
 submodule, and not the main `rust-lang/rust` repository.
 
 For subtrees, prefer sending a PR against the subtree's repository if it does
@@ -25,7 +25,7 @@ rustc-dev-guide change that does not accompany a compiler change).
 
 The [rustc-dev-guide] is meant to help document how rustc –the Rust compiler– works,
 as well as to help new contributors get involved in rustc development. It is recommended
-to read and understand the [rustc-dev-guide] before making a contribution. This guide
+that you read and understand the [rustc-dev-guide] before making a contribution. This guide
 talks about the different bots in the Rust ecosystem, the Rust development tools,
 bootstrapping, the compiler architecture, source code representation, and more.
 
@@ -33,7 +33,7 @@ bootstrapping, the compiler architecture, source code representation, and more.
 
 There are many ways you can get help when you're stuck. Rust has many platforms for this:
 [internals], [rust-zulip], and [rust-discord]. It is recommended to ask for help on
-the [rust-zulip], but any of these platforms are a great way to seek help and even
+the [rust-zulip], but any of these platforms are great ways to seek help and even
 find a mentor! You can learn more about asking questions and getting help in the
 [Asking Questions](https://rustc-dev-guide.rust-lang.org/getting-started.html#asking-questions) chapter of the [rustc-dev-guide].
 
diff --git a/Cargo.lock b/Cargo.lock
index 4e5040349e0..177ff6594e2 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -183,7 +183,20 @@ version = "0.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5d4744ed2eef2645831b441d8f5459689ade2ab27c854488fbab1fbe94fce1a7"
 dependencies = [
- "askama_derive",
+ "askama_derive 0.13.1",
+ "itoa",
+ "percent-encoding",
+ "serde",
+ "serde_json",
+]
+
+[[package]]
+name = "askama"
+version = "0.14.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f75363874b771be265f4ffe307ca705ef6f3baa19011c149da8674a87f1b75c4"
+dependencies = [
+ "askama_derive 0.14.0",
  "itoa",
  "percent-encoding",
  "serde",
@@ -196,7 +209,24 @@ version = "0.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d661e0f57be36a5c14c48f78d09011e67e0cb618f269cca9f2fd8d15b68c46ac"
 dependencies = [
- "askama_parser",
+ "askama_parser 0.13.0",
+ "basic-toml",
+ "memchr",
+ "proc-macro2",
+ "quote",
+ "rustc-hash 2.1.1",
+ "serde",
+ "serde_derive",
+ "syn 2.0.101",
+]
+
+[[package]]
+name = "askama_derive"
+version = "0.14.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "129397200fe83088e8a68407a8e2b1f826cf0086b21ccdb866a722c8bcd3a94f"
+dependencies = [
+ "askama_parser 0.14.0",
  "basic-toml",
  "memchr",
  "proc-macro2",
@@ -220,6 +250,18 @@ dependencies = [
 ]
 
 [[package]]
+name = "askama_parser"
+version = "0.14.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d6ab5630b3d5eaf232620167977f95eb51f3432fc76852328774afbd242d4358"
+dependencies = [
+ "memchr",
+ "serde",
+ "serde_derive",
+ "winnow 0.7.10",
+]
+
+[[package]]
 name = "autocfg"
 version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -540,7 +582,7 @@ name = "clippy"
 version = "0.1.89"
 dependencies = [
  "anstream",
- "askama",
+ "askama 0.13.1",
  "cargo_metadata 0.18.1",
  "clippy_config",
  "clippy_lints",
@@ -1389,7 +1431,7 @@ name = "generate-copyright"
 version = "0.1.0"
 dependencies = [
  "anyhow",
- "askama",
+ "askama 0.14.0",
  "cargo_metadata 0.18.1",
  "serde",
  "serde_json",
@@ -4622,7 +4664,7 @@ name = "rustdoc"
 version = "0.0.0"
 dependencies = [
  "arrayvec",
- "askama",
+ "askama 0.14.0",
  "base64",
  "expect-test",
  "indexmap",
diff --git a/compiler/rustc_ast_lowering/src/format.rs b/compiler/rustc_ast_lowering/src/format.rs
index 0de0319c667..17b443b8ecc 100644
--- a/compiler/rustc_ast_lowering/src/format.rs
+++ b/compiler/rustc_ast_lowering/src/format.rs
@@ -6,7 +6,7 @@ use rustc_ast::*;
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_hir as hir;
 use rustc_session::config::FmtDebug;
-use rustc_span::{Ident, Span, Symbol, kw, sym};
+use rustc_span::{Ident, Span, Symbol, sym};
 
 use super::LoweringContext;
 
@@ -418,7 +418,7 @@ fn expand_format_args<'hir>(
                 &FormatArgsPiece::Placeholder(_) => {
                     // Inject empty string before placeholders when not already preceded by a literal piece.
                     if i == 0 || matches!(fmt.template[i - 1], FormatArgsPiece::Placeholder(_)) {
-                        Some(ctx.expr_str(fmt.span, kw::Empty))
+                        Some(ctx.expr_str(fmt.span, sym::empty))
                     } else {
                         None
                     }
diff --git a/compiler/rustc_borrowck/src/type_check/free_region_relations.rs b/compiler/rustc_borrowck/src/type_check/free_region_relations.rs
index 92732aba29b..f642d34ea67 100644
--- a/compiler/rustc_borrowck/src/type_check/free_region_relations.rs
+++ b/compiler/rustc_borrowck/src/type_check/free_region_relations.rs
@@ -131,7 +131,8 @@ impl UniversalRegionRelations<'_> {
         assert!(self.universal_regions.is_universal_region(fr0));
 
         let mut external_parents = vec![];
-        let mut queue = vec![fr0];
+
+        let mut queue = vec![relation.minimal_scc_representative(fr0)];
 
         // Keep expanding `fr` into its parents until we reach
         // non-local regions.
diff --git a/compiler/rustc_codegen_gcc/src/consts.rs b/compiler/rustc_codegen_gcc/src/consts.rs
index 033afc0f8fb..8aed04c836a 100644
--- a/compiler/rustc_codegen_gcc/src/consts.rs
+++ b/compiler/rustc_codegen_gcc/src/consts.rs
@@ -154,7 +154,7 @@ impl<'gcc, 'tcx> StaticCodegenMethods for CodegenCx<'gcc, 'tcx> {
             // TODO(antoyo): set link section.
         }
 
-        if attrs.flags.contains(CodegenFnAttrFlags::USED)
+        if attrs.flags.contains(CodegenFnAttrFlags::USED_COMPILER)
             || attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER)
         {
             self.add_used_global(global.to_rvalue());
diff --git a/compiler/rustc_codegen_llvm/src/consts.rs b/compiler/rustc_codegen_llvm/src/consts.rs
index bf81eb648f8..fe2f2027327 100644
--- a/compiler/rustc_codegen_llvm/src/consts.rs
+++ b/compiler/rustc_codegen_llvm/src/consts.rs
@@ -527,7 +527,7 @@ impl<'ll> CodegenCx<'ll, '_> {
 
             base::set_variable_sanitizer_attrs(g, attrs);
 
-            if attrs.flags.contains(CodegenFnAttrFlags::USED) {
+            if attrs.flags.contains(CodegenFnAttrFlags::USED_COMPILER) {
                 // `USED` and `USED_LINKER` can't be used together.
                 assert!(!attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER));
 
@@ -551,7 +551,7 @@ impl<'ll> CodegenCx<'ll, '_> {
             }
             if attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER) {
                 // `USED` and `USED_LINKER` can't be used together.
-                assert!(!attrs.flags.contains(CodegenFnAttrFlags::USED));
+                assert!(!attrs.flags.contains(CodegenFnAttrFlags::USED_COMPILER));
 
                 self.add_used_global(g);
             }
diff --git a/compiler/rustc_codegen_ssa/messages.ftl b/compiler/rustc_codegen_ssa/messages.ftl
index 2621935eecf..acb4cbaa13f 100644
--- a/compiler/rustc_codegen_ssa/messages.ftl
+++ b/compiler/rustc_codegen_ssa/messages.ftl
@@ -1,5 +1,7 @@
 codegen_ssa_L4Bender_exporting_symbols_unimplemented = exporting symbols not implemented yet for L4Bender
 
+codegen_ssa_aarch64_softfloat_neon = enabling the `neon` target feature on the current target is unsound due to ABI issues
+
 codegen_ssa_add_native_library = failed to add native library {$library_path}: {$error}
 
 codegen_ssa_aix_strip_not_used = using host's `strip` binary to cross-compile to AIX which is not guaranteed to work
diff --git a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
index 96aec9769d2..e26f999773d 100644
--- a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
+++ b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
@@ -128,7 +128,7 @@ fn reachable_non_generics_provider(tcx: TyCtxt<'_>, _: LocalCrate) -> DefIdMap<S
                 } else {
                     SymbolExportKind::Text
                 },
-                used: codegen_attrs.flags.contains(CodegenFnAttrFlags::USED)
+                used: codegen_attrs.flags.contains(CodegenFnAttrFlags::USED_COMPILER)
                     || codegen_attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER)
                     || used,
             };
diff --git a/compiler/rustc_codegen_ssa/src/codegen_attrs.rs b/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
index aa55a0e0f14..4bcafa3be36 100644
--- a/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
+++ b/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
@@ -189,7 +189,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
                             )
                             .emit();
                         }
-                        codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
+                        codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED_COMPILER;
                     }
                     Some(_) => {
                         tcx.dcx().emit_err(errors::ExpectedUsedSymbol { span: attr.span() });
@@ -220,7 +220,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
                             || tcx.sess.target.is_like_windows
                             || tcx.sess.target.is_like_wasm);
                         codegen_fn_attrs.flags |= if is_like_elf {
-                            CodegenFnAttrFlags::USED
+                            CodegenFnAttrFlags::USED_COMPILER
                         } else {
                             CodegenFnAttrFlags::USED_LINKER
                         };
@@ -299,6 +299,7 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
                 }
                 from_target_feature_attr(
                     tcx,
+                    did,
                     attr,
                     rust_target_features,
                     &mut codegen_fn_attrs.target_features,
diff --git a/compiler/rustc_codegen_ssa/src/errors.rs b/compiler/rustc_codegen_ssa/src/errors.rs
index d49aac75d05..572d7b1e06a 100644
--- a/compiler/rustc_codegen_ssa/src/errors.rs
+++ b/compiler/rustc_codegen_ssa/src/errors.rs
@@ -1316,3 +1316,7 @@ pub(crate) struct XcrunSdkPathWarning {
     pub sdk_name: &'static str,
     pub stderr: String,
 }
+
+#[derive(LintDiagnostic)]
+#[diag(codegen_ssa_aarch64_softfloat_neon)]
+pub(crate) struct Aarch64SoftfloatNeon;
diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs
index 950f19a6f0f..600d6ff6801 100644
--- a/compiler/rustc_codegen_ssa/src/mir/block.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/block.rs
@@ -1181,6 +1181,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             (_, Some(llfn)) => llfn,
             _ => span_bug!(span, "no instance or llfn for call"),
         };
+        self.set_debug_loc(bx, mir::SourceInfo { span: fn_span, ..source_info });
         helper.do_call(
             self,
             bx,
diff --git a/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs b/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs
index 5924c8991ad..f731613d67e 100644
--- a/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs
@@ -10,7 +10,7 @@ use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
 use rustc_middle::ty::{Instance, Ty};
 use rustc_middle::{bug, mir, ty};
 use rustc_session::config::DebugInfo;
-use rustc_span::{BytePos, Span, Symbol, hygiene, kw};
+use rustc_span::{BytePos, Span, Symbol, hygiene, sym};
 
 use super::operand::{OperandRef, OperandValue};
 use super::place::{PlaceRef, PlaceValue};
@@ -283,7 +283,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 // (after #67586 gets fixed).
                 None
             } else {
-                let name = kw::Empty;
+                let name = sym::empty;
                 let decl = &self.mir.local_decls[local];
                 let dbg_var = if full_debug_info {
                     self.adjusted_span_and_dbg_scope(decl.source_info).map(
@@ -318,7 +318,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             None
         } else {
             Some(match whole_local_var.or(fallback_var.clone()) {
-                Some(var) if var.name != kw::Empty => var.name.to_string(),
+                Some(var) if var.name != sym::empty => var.name.to_string(),
                 _ => format!("{local:?}"),
             })
         };
diff --git a/compiler/rustc_codegen_ssa/src/target_features.rs b/compiler/rustc_codegen_ssa/src/target_features.rs
index 3ecea522837..6bb3150c1c5 100644
--- a/compiler/rustc_codegen_ssa/src/target_features.rs
+++ b/compiler/rustc_codegen_ssa/src/target_features.rs
@@ -8,6 +8,7 @@ use rustc_hir::def_id::{DefId, LOCAL_CRATE, LocalDefId};
 use rustc_middle::middle::codegen_fn_attrs::TargetFeature;
 use rustc_middle::query::Providers;
 use rustc_middle::ty::TyCtxt;
+use rustc_session::lint::builtin::AARCH64_SOFTFLOAT_NEON;
 use rustc_session::parse::feature_err;
 use rustc_span::{Span, Symbol, sym};
 use rustc_target::target_features::{self, Stability};
@@ -18,6 +19,7 @@ use crate::errors;
 /// Enabled target features are added to `target_features`.
 pub(crate) fn from_target_feature_attr(
     tcx: TyCtxt<'_>,
+    did: LocalDefId,
     attr: &hir::Attribute,
     rust_target_features: &UnordMap<String, target_features::Stability>,
     target_features: &mut Vec<TargetFeature>,
@@ -92,11 +94,22 @@ pub(crate) fn from_target_feature_attr(
                     // generating code so "it's fine".
                     if !tcx.sess.opts.actually_rustdoc {
                         if abi_feature_constraints.incompatible.contains(&name.as_str()) {
-                            tcx.dcx().emit_err(errors::ForbiddenTargetFeatureAttr {
-                                span: item.span(),
-                                feature: name.as_str(),
-                                reason: "this feature is incompatible with the target ABI",
-                            });
+                            // For "neon" specifically, we emit an FCW instead of a hard error.
+                            // See <https://github.com/rust-lang/rust/issues/134375>.
+                            if tcx.sess.target.arch == "aarch64" && name.as_str() == "neon" {
+                                tcx.emit_node_span_lint(
+                                    AARCH64_SOFTFLOAT_NEON,
+                                    tcx.local_def_id_to_hir_id(did),
+                                    item.span(),
+                                    errors::Aarch64SoftfloatNeon,
+                                );
+                            } else {
+                                tcx.dcx().emit_err(errors::ForbiddenTargetFeatureAttr {
+                                    span: item.span(),
+                                    feature: name.as_str(),
+                                    reason: "this feature is incompatible with the target ABI",
+                                });
+                            }
                         }
                     }
                     target_features.push(TargetFeature { name, implied: name != feature_sym })
diff --git a/compiler/rustc_data_structures/src/transitive_relation.rs b/compiler/rustc_data_structures/src/transitive_relation.rs
index 33ac279f3e0..31abea93819 100644
--- a/compiler/rustc_data_structures/src/transitive_relation.rs
+++ b/compiler/rustc_data_structures/src/transitive_relation.rs
@@ -354,6 +354,20 @@ impl<T: Eq + Hash + Copy> TransitiveRelation<T> {
             .collect()
     }
 
+    /// Given an element A, elements B with the lowest index such that `A R B`
+    /// and `B R A`, or `A` if no such element exists.
+    pub fn minimal_scc_representative(&self, a: T) -> T {
+        match self.index(a) {
+            Some(a_i) => self.with_closure(|closure| {
+                closure
+                    .iter(a_i.0)
+                    .find(|i| closure.contains(*i, a_i.0))
+                    .map_or(a, |i| self.elements[i])
+            }),
+            None => a,
+        }
+    }
+
     fn with_closure<OP, R>(&self, op: OP) -> R
     where
         OP: FnOnce(&BitMatrix<usize, usize>) -> R,
diff --git a/compiler/rustc_data_structures/src/transitive_relation/tests.rs b/compiler/rustc_data_structures/src/transitive_relation/tests.rs
index e756c546e41..cba14b5b64b 100644
--- a/compiler/rustc_data_structures/src/transitive_relation/tests.rs
+++ b/compiler/rustc_data_structures/src/transitive_relation/tests.rs
@@ -376,3 +376,44 @@ fn parent() {
     let p = relation.postdom_parent(3);
     assert_eq!(p, Some(0));
 }
+
+#[test]
+fn minimal_scc_representative_1() {
+    //      +---------+
+    //      v         |
+    // a -> c -> d -> e
+    //           ^    ^
+    //           |    |
+    //           b ---+
+
+    // "digraph { a -> c -> d -> e -> c; b -> d; b -> e; }",
+    let mut relation = TransitiveRelationBuilder::default();
+    relation.add("a", "c");
+    relation.add("c", "d");
+    relation.add("d", "e");
+    relation.add("e", "c");
+    relation.add("b", "d");
+    relation.add("b", "e");
+    let relation = relation.freeze();
+
+    assert_eq!(relation.minimal_scc_representative("a"), "a");
+    assert_eq!(relation.minimal_scc_representative("b"), "b");
+    assert_eq!(relation.minimal_scc_representative("c"), "c");
+    assert_eq!(relation.minimal_scc_representative("d"), "c");
+    assert_eq!(relation.minimal_scc_representative("e"), "c");
+}
+
+#[test]
+fn minimal_scc_representative_2() {
+    // "digraph { a -> b; a -> a; b -> a; c -> c}",
+    let mut relation = TransitiveRelationBuilder::default();
+    relation.add("a", "b");
+    relation.add("b", "a");
+    relation.add("a", "a");
+    relation.add("c", "c");
+    let relation = relation.freeze();
+
+    assert_eq!(relation.minimal_scc_representative("a"), "a");
+    assert_eq!(relation.minimal_scc_representative("b"), "a");
+    assert_eq!(relation.minimal_scc_representative("c"), "c");
+}
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index fa1d1ec0a86..f63ab303689 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -85,7 +85,7 @@ impl From<Ident> for LifetimeSyntax {
     fn from(ident: Ident) -> Self {
         let name = ident.name;
 
-        if name == kw::Empty {
+        if name == sym::empty {
             unreachable!("A lifetime name should never be empty");
         } else if name == kw::UnderscoreLifetime {
             LifetimeSyntax::Anonymous
diff --git a/compiler/rustc_hir_analysis/messages.ftl b/compiler/rustc_hir_analysis/messages.ftl
index f7f2b78f052..a3a0e276f74 100644
--- a/compiler/rustc_hir_analysis/messages.ftl
+++ b/compiler/rustc_hir_analysis/messages.ftl
@@ -37,7 +37,7 @@ hir_analysis_assoc_kind_mismatch = expected {$expected}, found {$got}
 
 hir_analysis_assoc_kind_mismatch_wrap_in_braces_sugg = consider adding braces here
 
-hir_analysis_associated_type_trait_uninferred_generic_params = cannot use the associated {$what} of a trait with uninferred generic parameters
+hir_analysis_associated_type_trait_uninferred_generic_params = cannot use the {$what} of a trait with uninferred generic parameters
     .suggestion = use a fully qualified path with inferred lifetimes
 
 hir_analysis_associated_type_trait_uninferred_generic_params_multipart_suggestion = use a fully qualified path with explicit lifetimes
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
index 4520fbe352c..f5206d9a015 100644
--- a/compiler/rustc_hir_analysis/src/collect.rs
+++ b/compiler/rustc_hir_analysis/src/collect.rs
@@ -44,7 +44,6 @@ use rustc_trait_selection::traits::ObligationCtxt;
 use tracing::{debug, instrument};
 
 use crate::errors;
-use crate::hir_ty_lowering::errors::assoc_tag_str;
 use crate::hir_ty_lowering::{FeedConstTy, HirTyLowerer, RegionInferReason};
 
 pub(crate) mod dump;
@@ -89,6 +88,7 @@ pub(crate) fn provide(providers: &mut Providers) {
         opaque_ty_origin,
         rendered_precise_capturing_args,
         const_param_default,
+        anon_const_kind,
         ..*providers
     };
 }
@@ -444,13 +444,12 @@ impl<'tcx> HirTyLowerer<'tcx> for ItemCtxt<'tcx> {
         self.tcx.at(span).type_param_predicates((self.item_def_id, def_id, assoc_ident))
     }
 
-    fn lower_assoc_shared(
+    fn lower_assoc_item_path(
         &self,
         span: Span,
         item_def_id: DefId,
         item_segment: &rustc_hir::PathSegment<'tcx>,
         poly_trait_ref: ty::PolyTraitRef<'tcx>,
-        assoc_tag: ty::AssocTag,
     ) -> Result<(DefId, ty::GenericArgsRef<'tcx>), ErrorGuaranteed> {
         if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
             let item_args = self.lowerer().lower_generic_args_of_assoc_item(
@@ -525,7 +524,7 @@ impl<'tcx> HirTyLowerer<'tcx> for ItemCtxt<'tcx> {
                 inferred_sugg,
                 bound,
                 mpart_sugg,
-                what: assoc_tag_str(assoc_tag),
+                what: self.tcx.def_descr(item_def_id),
             }))
         }
     }
@@ -1828,3 +1827,27 @@ fn const_param_default<'tcx>(
         .lower_const_arg(default_ct, FeedConstTy::Param(def_id.to_def_id(), identity_args));
     ty::EarlyBinder::bind(ct)
 }
+
+fn anon_const_kind<'tcx>(tcx: TyCtxt<'tcx>, def: LocalDefId) -> ty::AnonConstKind {
+    let hir_id = tcx.local_def_id_to_hir_id(def);
+    let const_arg_id = tcx.parent_hir_id(hir_id);
+    match tcx.hir_node(const_arg_id) {
+        hir::Node::ConstArg(_) => {
+            if tcx.features().generic_const_exprs() {
+                ty::AnonConstKind::GCE
+            } else if tcx.features().min_generic_const_args() {
+                ty::AnonConstKind::MCG
+            } else if let hir::Node::Expr(hir::Expr {
+                kind: hir::ExprKind::Repeat(_, repeat_count),
+                ..
+            }) = tcx.hir_node(tcx.parent_hir_id(const_arg_id))
+                && repeat_count.hir_id == const_arg_id
+            {
+                ty::AnonConstKind::RepeatExprCount
+            } else {
+                ty::AnonConstKind::MCG
+            }
+        }
+        _ => ty::AnonConstKind::NonTypeSystem,
+    }
+}
diff --git a/compiler/rustc_hir_analysis/src/collect/generics_of.rs b/compiler/rustc_hir_analysis/src/collect/generics_of.rs
index 2bed28d7b71..7eb896f0bf1 100644
--- a/compiler/rustc_hir_analysis/src/collect/generics_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/generics_of.rs
@@ -104,19 +104,27 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
                 }
             }
 
-            if in_param_ty {
-                // We do not allow generic parameters in anon consts if we are inside
-                // of a const parameter type, e.g. `struct Foo<const N: usize, const M: [u8; N]>` is not allowed.
-                None
-            } else if tcx.features().generic_const_exprs() {
-                let parent_node = tcx.parent_hir_node(hir_id);
-                debug!(?parent_node);
-                if let Node::Variant(Variant { disr_expr: Some(constant), .. }) = parent_node
-                    && constant.hir_id == hir_id
-                {
-                    // enum variant discriminants are not allowed to use any kind of generics
-                    None
-                } else if let Some(param_id) = tcx.hir_opt_const_param_default_param_def_id(hir_id)
+            match tcx.anon_const_kind(def_id) {
+                // Stable: anon consts are not able to use any generic parameters...
+                ty::AnonConstKind::MCG => None,
+                // we provide generics to repeat expr counts as a backwards compatibility hack. #76200
+                ty::AnonConstKind::RepeatExprCount => Some(parent_did),
+
+                // Even GCE anon const should not be allowed to use generic parameters as it would be
+                // trivially forward declared uses once desugared. E.g. `const N: [u8; ANON::<N>]`.
+                //
+                // We could potentially mirror the hack done for defaults of generic parameters but
+                // this case just doesn't come up much compared to `const N: u32 = ...`. Long term the
+                // hack for defaulted parameters should be removed eventually anyway.
+                ty::AnonConstKind::GCE if in_param_ty => None,
+                // GCE anon consts as a default for a generic parameter should have their provided generics
+                // "truncated" up to whatever generic parameter this anon const is within the default of.
+                //
+                // FIXME(generic_const_exprs): This only handles `const N: usize = /*defid*/` but not type
+                // parameter defaults, e.g. `T = Foo</*defid*/>`.
+                ty::AnonConstKind::GCE
+                    if let Some(param_id) =
+                        tcx.hir_opt_const_param_default_param_def_id(hir_id) =>
                 {
                     // If the def_id we are calling generics_of on is an anon ct default i.e:
                     //
@@ -160,36 +168,17 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
                         has_self: generics.has_self,
                         has_late_bound_regions: generics.has_late_bound_regions,
                     };
-                } else {
-                    // HACK(eddyb) this provides the correct generics when
-                    // `feature(generic_const_expressions)` is enabled, so that const expressions
-                    // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
-                    //
-                    // Note that we do not supply the parent generics when using
-                    // `min_const_generics`.
-                    Some(parent_did)
                 }
-            } else {
-                let parent_node = tcx.parent_hir_node(hir_id);
-                let parent_node = match parent_node {
-                    Node::ConstArg(ca) => tcx.parent_hir_node(ca.hir_id),
-                    _ => parent_node,
-                };
-                match parent_node {
-                    // HACK(eddyb) this provides the correct generics for repeat
-                    // expressions' count (i.e. `N` in `[x; N]`), and explicit
-                    // `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`),
-                    // as they shouldn't be able to cause query cycle errors.
-                    Node::Expr(Expr { kind: ExprKind::Repeat(_, ct), .. })
-                        if ct.anon_const_hir_id() == Some(hir_id) =>
-                    {
-                        Some(parent_did)
-                    }
-                    Node::TyPat(_) => Some(parent_did),
-                    // Field default values inherit the ADT's generics.
-                    Node::Field(_) => Some(parent_did),
-                    _ => None,
+                ty::AnonConstKind::GCE => Some(parent_did),
+
+                // Field defaults are allowed to use generic parameters, e.g. `field: u32 = /*defid: N + 1*/`
+                ty::AnonConstKind::NonTypeSystem
+                    if matches!(tcx.parent_hir_node(hir_id), Node::TyPat(_) | Node::Field(_)) =>
+                {
+                    Some(parent_did)
                 }
+                // Default to no generic parameters for other kinds of anon consts
+                ty::AnonConstKind::NonTypeSystem => None,
             }
         }
         Node::ConstBlock(_)
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs
index 4419d5dc7d6..bdc42c7a2d9 100644
--- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs
+++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs
@@ -4,9 +4,9 @@ use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
 use rustc_errors::codes::*;
 use rustc_errors::struct_span_code_err;
 use rustc_hir as hir;
+use rustc_hir::AmbigArg;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{DefId, LocalDefId};
-use rustc_hir::{AmbigArg, HirId};
 use rustc_middle::bug;
 use rustc_middle::ty::{
     self as ty, IsSuggestable, Ty, TyCtxt, TypeFoldable, TypeSuperVisitable, TypeVisitable,
@@ -309,7 +309,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                     false => "`?Sized`",
                 };
                 // There was a `?Trait` bound, but it was neither `?Sized` nor `experimental_default_bounds`.
-                tcx.dcx().span_err(
+                self.dcx().span_err(
                     unbound.span,
                     format!(
                         "relaxing a default bound only does something for {}; \
@@ -675,7 +675,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
 
                 // Good error for `where Trait::method(..): Send`.
                 let Some(self_ty) = opt_self_ty else {
-                    let guar = self.error_missing_qpath_self_ty(
+                    let guar = self.report_missing_self_ty_for_resolved_path(
                         trait_def_id,
                         hir_ty.span,
                         item_segment,
@@ -713,120 +713,51 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                     Err(guar) => Ty::new_error(tcx, guar),
                 }
             }
-            hir::QPath::TypeRelative(qself, item_segment)
-                if item_segment.args.is_some_and(|args| {
+            hir::QPath::TypeRelative(hir_self_ty, segment)
+                if segment.args.is_some_and(|args| {
                     matches!(args.parenthesized, hir::GenericArgsParentheses::ReturnTypeNotation)
                 }) =>
             {
-                match self
-                    .resolve_type_relative_return_type_notation(
-                        qself,
-                        item_segment,
-                        hir_ty.hir_id,
-                        hir_ty.span,
-                    )
-                    .and_then(|(candidate, item_def_id)| {
-                        self.lower_return_type_notation_ty(candidate, item_def_id, hir_ty.span)
-                    }) {
-                    Ok(ty) => Ty::new_alias(tcx, ty::Projection, ty),
-                    Err(guar) => Ty::new_error(tcx, guar),
-                }
-            }
-            _ => self.lower_ty(hir_ty),
-        }
-    }
-
-    /// Perform type-dependent lookup for a *method* for return type notation.
-    /// This generally mirrors `<dyn HirTyLowerer>::lower_assoc_path`.
-    fn resolve_type_relative_return_type_notation(
-        &self,
-        qself: &'tcx hir::Ty<'tcx>,
-        item_segment: &'tcx hir::PathSegment<'tcx>,
-        qpath_hir_id: HirId,
-        span: Span,
-    ) -> Result<(ty::PolyTraitRef<'tcx>, DefId), ErrorGuaranteed> {
-        let tcx = self.tcx();
-        let qself_ty = self.lower_ty(qself);
-        let assoc_ident = item_segment.ident;
-        let qself_res = if let hir::TyKind::Path(hir::QPath::Resolved(_, path)) = &qself.kind {
-            path.res
-        } else {
-            Res::Err
-        };
-
-        let bound = match (qself_ty.kind(), qself_res) {
-            (_, Res::SelfTyAlias { alias_to: impl_def_id, is_trait_impl: true, .. }) => {
-                // `Self` in an impl of a trait -- we have a concrete self type and a
-                // trait reference.
-                let Some(trait_ref) = tcx.impl_trait_ref(impl_def_id) else {
-                    // A cycle error occurred, most likely.
-                    self.dcx().span_bug(span, "expected cycle error");
-                };
-
-                self.probe_single_bound_for_assoc_item(
-                    || {
-                        traits::supertraits(
-                            tcx,
-                            ty::Binder::dummy(trait_ref.instantiate_identity()),
-                        )
-                    },
-                    AssocItemQSelf::SelfTyAlias,
+                let self_ty = self.lower_ty(hir_self_ty);
+                let (item_def_id, bound) = match self.resolve_type_relative_path(
+                    self_ty,
+                    hir_self_ty,
                     ty::AssocTag::Fn,
-                    assoc_ident,
-                    span,
+                    segment,
+                    hir_ty.hir_id,
+                    hir_ty.span,
                     None,
-                )?
-            }
-            (
-                &ty::Param(_),
-                Res::SelfTyParam { trait_: param_did } | Res::Def(DefKind::TyParam, param_did),
-            ) => self.probe_single_ty_param_bound_for_assoc_item(
-                param_did.expect_local(),
-                qself.span,
-                ty::AssocTag::Fn,
-                assoc_ident,
-                span,
-            )?,
-            _ => {
-                if let Err(reported) = qself_ty.error_reported() {
-                    return Err(reported);
-                } else {
-                    // FIXME(return_type_notation): Provide some structured suggestion here.
-                    let err = struct_span_code_err!(
-                        self.dcx(),
-                        span,
-                        E0223,
-                        "ambiguous associated function"
+                ) {
+                    Ok(result) => result,
+                    Err(guar) => return Ty::new_error(tcx, guar),
+                };
+
+                // Don't let `T::method` resolve to some `for<'a> <T as Tr<'a>>::method`,
+                // which may happen via a higher-ranked where clause or supertrait.
+                // This is the same restrictions as associated types; even though we could
+                // support it, it just makes things a lot more difficult to support in
+                // `resolve_bound_vars`, since we'd need to introduce those as elided
+                // bound vars on the where clause too.
+                if bound.has_bound_vars() {
+                    return Ty::new_error(
+                        tcx,
+                        self.dcx().emit_err(errors::AssociatedItemTraitUninferredGenericParams {
+                            span: hir_ty.span,
+                            inferred_sugg: Some(hir_ty.span.with_hi(segment.ident.span.lo())),
+                            bound: format!("{}::", tcx.anonymize_bound_vars(bound).skip_binder()),
+                            mpart_sugg: None,
+                            what: tcx.def_descr(item_def_id),
+                        }),
                     );
-                    return Err(err.emit());
                 }
-            }
-        };
 
-        // Don't let `T::method` resolve to some `for<'a> <T as Tr<'a>>::method`,
-        // which may happen via a higher-ranked where clause or supertrait.
-        // This is the same restrictions as associated types; even though we could
-        // support it, it just makes things a lot more difficult to support in
-        // `resolve_bound_vars`, since we'd need to introduce those as elided
-        // bound vars on the where clause too.
-        if bound.has_bound_vars() {
-            return Err(self.tcx().dcx().emit_err(
-                errors::AssociatedItemTraitUninferredGenericParams {
-                    span,
-                    inferred_sugg: Some(span.with_hi(item_segment.ident.span.lo())),
-                    bound: format!("{}::", tcx.anonymize_bound_vars(bound).skip_binder(),),
-                    mpart_sugg: None,
-                    what: "function",
-                },
-            ));
+                match self.lower_return_type_notation_ty(bound, item_def_id, hir_ty.span) {
+                    Ok(ty) => Ty::new_alias(tcx, ty::Projection, ty),
+                    Err(guar) => Ty::new_error(tcx, guar),
+                }
+            }
+            _ => self.lower_ty(hir_ty),
         }
-
-        let trait_def_id = bound.def_id();
-        let assoc_ty = self
-            .probe_assoc_item(assoc_ident, ty::AssocTag::Fn, qpath_hir_id, span, trait_def_id)
-            .expect("failed to find associated type");
-
-        Ok((bound, assoc_ty.def_id))
     }
 
     /// Do the common parts of lowering an RTN type. This involves extending the
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/cmse.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/cmse.rs
index d1ee5a5494c..ebeb3b58208 100644
--- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/cmse.rs
+++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/cmse.rs
@@ -35,7 +35,7 @@ pub(crate) fn validate_cmse_abi<'tcx>(
                     _ => tcx.hir_span(hir_id),
                 };
                 struct_span_code_err!(
-                    tcx.dcx(),
+                    dcx,
                     span,
                     E0781,
                     "the `\"C-cmse-nonsecure-call\"` ABI is only allowed on function pointers"
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs
index f6e5149bd2b..9e44b645aca 100644
--- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs
+++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/dyn_compatibility.rs
@@ -78,15 +78,13 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
 
         // We  don't support empty trait objects.
         if regular_traits.is_empty() && auto_traits.is_empty() {
-            let guar = self.report_trait_object_with_no_traits_error(
-                span,
-                user_written_bounds.iter().copied(),
-            );
+            let guar =
+                self.report_trait_object_with_no_traits(span, user_written_bounds.iter().copied());
             return Ty::new_error(tcx, guar);
         }
         // We don't support >1 principal
         if regular_traits.len() > 1 {
-            let guar = self.report_trait_object_addition_traits_error(&regular_traits);
+            let guar = self.report_trait_object_addition_traits(&regular_traits);
             return Ty::new_error(tcx, guar);
         }
         // Don't create a dyn trait if we have errors in the principal.
@@ -132,7 +130,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                     if references_self {
                         // With trait alias and type alias combined, type resolver
                         // may not be able to catch all illegal `Self` usages (issue 139082)
-                        let guar = tcx.dcx().emit_err(SelfInTypeAlias { span });
+                        let guar = self.dcx().emit_err(SelfInTypeAlias { span });
                         b.term = replace_dummy_self_with_error(tcx, b.term, guar);
                     }
                 }
@@ -360,7 +358,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                     hir_bound.trait_ref.path.res == Res::Def(DefKind::Trait, trait_ref.def_id)
                         && hir_bound.span.contains(span)
                 });
-                self.complain_about_missing_type_params(
+                self.report_missing_type_params(
                     missing_type_params,
                     trait_ref.def_id,
                     span,
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs
index 3759a224ff7..45fee0fa402 100644
--- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs
+++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs
@@ -3,11 +3,12 @@ use rustc_data_structures::sorted_map::SortedMap;
 use rustc_data_structures::unord::UnordMap;
 use rustc_errors::codes::*;
 use rustc_errors::{
-    Applicability, Diag, ErrorGuaranteed, MultiSpan, listify, pluralize, struct_span_code_err,
+    Applicability, Diag, ErrorGuaranteed, MultiSpan, SuggestionStyle, listify, pluralize,
+    struct_span_code_err,
 };
-use rustc_hir as hir;
 use rustc_hir::def::{CtorOf, DefKind, Res};
 use rustc_hir::def_id::DefId;
+use rustc_hir::{self as hir, HirId};
 use rustc_middle::bug;
 use rustc_middle::ty::fast_reject::{TreatParams, simplify_type};
 use rustc_middle::ty::print::{PrintPolyTraitRefExt as _, PrintTraitRefExt as _};
@@ -23,6 +24,7 @@ use rustc_trait_selection::traits::{
     FulfillmentError, dyn_compatibility_violations_for_assoc_item,
 };
 use smallvec::SmallVec;
+use tracing::debug;
 
 use crate::errors::{
     self, AssocItemConstraintsNotAllowedHere, ManualImplementation, MissingTypeParams,
@@ -34,7 +36,7 @@ use crate::hir_ty_lowering::{AssocItemQSelf, HirTyLowerer};
 impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
     /// On missing type parameters, emit an E0393 error and provide a structured suggestion using
     /// the type parameter's name as a placeholder.
-    pub(crate) fn complain_about_missing_type_params(
+    pub(crate) fn report_missing_type_params(
         &self,
         missing_type_params: Vec<Symbol>,
         def_id: DefId,
@@ -56,7 +58,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
 
     /// When the code is using the `Fn` traits directly, instead of the `Fn(A) -> B` syntax, emit
     /// an error and attempt to build a reasonable structured suggestion.
-    pub(crate) fn complain_about_internal_fn_trait(
+    pub(crate) fn report_internal_fn_trait(
         &self,
         span: Span,
         trait_def_id: DefId,
@@ -112,7 +114,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         }
     }
 
-    pub(super) fn complain_about_assoc_item_not_found<I>(
+    pub(super) fn report_unresolved_assoc_item<I>(
         &self,
         all_candidates: impl Fn() -> I,
         qself: AssocItemQSelf,
@@ -132,7 +134,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 .filter_by_name_unhygienic(assoc_ident.name)
                 .find(|item| tcx.hygienic_eq(assoc_ident, item.ident(tcx), r.def_id()))
         }) {
-            return self.complain_about_assoc_kind_mismatch(
+            return self.report_assoc_kind_mismatch(
                 assoc_item,
                 assoc_tag,
                 assoc_ident,
@@ -331,7 +333,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         self.dcx().emit_err(err)
     }
 
-    fn complain_about_assoc_kind_mismatch(
+    fn report_assoc_kind_mismatch(
         &self,
         assoc_item: &ty::AssocItem,
         assoc_tag: ty::AssocTag,
@@ -396,12 +398,177 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         })
     }
 
-    pub(super) fn report_ambiguous_assoc(
+    pub(crate) fn report_missing_self_ty_for_resolved_path(
+        &self,
+        trait_def_id: DefId,
+        span: Span,
+        item_segment: &hir::PathSegment<'tcx>,
+        assoc_tag: ty::AssocTag,
+    ) -> ErrorGuaranteed {
+        let tcx = self.tcx();
+        let path_str = tcx.def_path_str(trait_def_id);
+
+        let def_id = self.item_def_id();
+        debug!(item_def_id = ?def_id);
+
+        // FIXME: document why/how this is different from `tcx.local_parent(def_id)`
+        let parent_def_id = tcx.hir_get_parent_item(tcx.local_def_id_to_hir_id(def_id)).to_def_id();
+        debug!(?parent_def_id);
+
+        // If the trait in segment is the same as the trait defining the item,
+        // use the `<Self as ..>` syntax in the error.
+        let is_part_of_self_trait_constraints = def_id.to_def_id() == trait_def_id;
+        let is_part_of_fn_in_self_trait = parent_def_id == trait_def_id;
+
+        let type_names = if is_part_of_self_trait_constraints || is_part_of_fn_in_self_trait {
+            vec!["Self".to_string()]
+        } else {
+            // Find all the types that have an `impl` for the trait.
+            tcx.all_impls(trait_def_id)
+                .filter_map(|impl_def_id| tcx.impl_trait_header(impl_def_id))
+                .filter(|header| {
+                    // Consider only accessible traits
+                    tcx.visibility(trait_def_id).is_accessible_from(self.item_def_id(), tcx)
+                        && header.polarity != ty::ImplPolarity::Negative
+                })
+                .map(|header| header.trait_ref.instantiate_identity().self_ty())
+                // We don't care about blanket impls.
+                .filter(|self_ty| !self_ty.has_non_region_param())
+                .map(|self_ty| tcx.erase_regions(self_ty).to_string())
+                .collect()
+        };
+        // FIXME: also look at `tcx.generics_of(self.item_def_id()).params` any that
+        // references the trait. Relevant for the first case in
+        // `src/test/ui/associated-types/associated-types-in-ambiguous-context.rs`
+        self.report_ambiguous_assoc_item_path(
+            span,
+            &type_names,
+            &[path_str],
+            item_segment.ident,
+            assoc_tag,
+        )
+    }
+
+    pub(super) fn report_unresolved_type_relative_path(
+        &self,
+        self_ty: Ty<'tcx>,
+        hir_self_ty: &hir::Ty<'_>,
+        assoc_tag: ty::AssocTag,
+        ident: Ident,
+        qpath_hir_id: HirId,
+        span: Span,
+        variant_def_id: Option<DefId>,
+    ) -> ErrorGuaranteed {
+        let tcx = self.tcx();
+        let kind_str = assoc_tag_str(assoc_tag);
+        if variant_def_id.is_some() {
+            // Variant in type position
+            let msg = format!("expected {kind_str}, found variant `{ident}`");
+            self.dcx().span_err(span, msg)
+        } else if self_ty.is_enum() {
+            let mut err = self.dcx().create_err(errors::NoVariantNamed {
+                span: ident.span,
+                ident,
+                ty: self_ty,
+            });
+
+            let adt_def = self_ty.ty_adt_def().expect("enum is not an ADT");
+            if let Some(variant_name) = find_best_match_for_name(
+                &adt_def.variants().iter().map(|variant| variant.name).collect::<Vec<Symbol>>(),
+                ident.name,
+                None,
+            ) && let Some(variant) = adt_def.variants().iter().find(|s| s.name == variant_name)
+            {
+                let mut suggestion = vec![(ident.span, variant_name.to_string())];
+                if let hir::Node::Stmt(&hir::Stmt { kind: hir::StmtKind::Semi(expr), .. })
+                | hir::Node::Expr(expr) = tcx.parent_hir_node(qpath_hir_id)
+                    && let hir::ExprKind::Struct(..) = expr.kind
+                {
+                    match variant.ctor {
+                        None => {
+                            // struct
+                            suggestion = vec![(
+                                ident.span.with_hi(expr.span.hi()),
+                                if variant.fields.is_empty() {
+                                    format!("{variant_name} {{}}")
+                                } else {
+                                    format!(
+                                        "{variant_name} {{ {} }}",
+                                        variant
+                                            .fields
+                                            .iter()
+                                            .map(|f| format!("{}: /* value */", f.name))
+                                            .collect::<Vec<_>>()
+                                            .join(", ")
+                                    )
+                                },
+                            )];
+                        }
+                        Some((hir::def::CtorKind::Fn, def_id)) => {
+                            // tuple
+                            let fn_sig = tcx.fn_sig(def_id).instantiate_identity();
+                            let inputs = fn_sig.inputs().skip_binder();
+                            suggestion = vec![(
+                                ident.span.with_hi(expr.span.hi()),
+                                format!(
+                                    "{variant_name}({})",
+                                    inputs
+                                        .iter()
+                                        .map(|i| format!("/* {i} */"))
+                                        .collect::<Vec<_>>()
+                                        .join(", ")
+                                ),
+                            )];
+                        }
+                        Some((hir::def::CtorKind::Const, _)) => {
+                            // unit
+                            suggestion = vec![(
+                                ident.span.with_hi(expr.span.hi()),
+                                variant_name.to_string(),
+                            )];
+                        }
+                    }
+                }
+                err.multipart_suggestion_verbose(
+                    "there is a variant with a similar name",
+                    suggestion,
+                    Applicability::HasPlaceholders,
+                );
+            } else {
+                err.span_label(ident.span, format!("variant not found in `{self_ty}`"));
+            }
+
+            if let Some(sp) = tcx.hir_span_if_local(adt_def.did()) {
+                err.span_label(sp, format!("variant `{ident}` not found here"));
+            }
+
+            err.emit()
+        } else if let Err(reported) = self_ty.error_reported() {
+            reported
+        } else {
+            match self.maybe_report_similar_assoc_fn(span, self_ty, hir_self_ty) {
+                Ok(()) => {}
+                Err(reported) => return reported,
+            }
+
+            let traits: Vec<_> = self.probe_traits_that_match_assoc_ty(self_ty, ident);
+
+            self.report_ambiguous_assoc_item_path(
+                span,
+                &[self_ty.to_string()],
+                &traits,
+                ident,
+                assoc_tag,
+            )
+        }
+    }
+
+    pub(super) fn report_ambiguous_assoc_item_path(
         &self,
         span: Span,
         types: &[String],
         traits: &[String],
-        name: Symbol,
+        ident: Ident,
         assoc_tag: ty::AssocTag,
     ) -> ErrorGuaranteed {
         let kind_str = assoc_tag_str(assoc_tag);
@@ -421,6 +588,8 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 Applicability::MachineApplicable,
             );
         } else {
+            let sugg_sp = span.until(ident.span);
+
             let mut types = types.to_vec();
             types.sort();
             let mut traits = traits.to_vec();
@@ -428,76 +597,79 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             match (&types[..], &traits[..]) {
                 ([], []) => {
                     err.span_suggestion_verbose(
-                        span,
+                        sugg_sp,
                         format!(
                             "if there were a type named `Type` that implements a trait named \
-                             `Trait` with associated {kind_str} `{name}`, you could use the \
+                             `Trait` with associated {kind_str} `{ident}`, you could use the \
                              fully-qualified path",
                         ),
-                        format!("<Type as Trait>::{name}"),
+                        "<Type as Trait>::",
                         Applicability::HasPlaceholders,
                     );
                 }
                 ([], [trait_str]) => {
                     err.span_suggestion_verbose(
-                        span,
+                        sugg_sp,
                         format!(
                             "if there were a type named `Example` that implemented `{trait_str}`, \
                              you could use the fully-qualified path",
                         ),
-                        format!("<Example as {trait_str}>::{name}"),
+                        format!("<Example as {trait_str}>::"),
                         Applicability::HasPlaceholders,
                     );
                 }
                 ([], traits) => {
-                    err.span_suggestions(
-                        span,
+                    err.span_suggestions_with_style(
+                        sugg_sp,
                         format!(
                             "if there were a type named `Example` that implemented one of the \
-                             traits with associated {kind_str} `{name}`, you could use the \
+                             traits with associated {kind_str} `{ident}`, you could use the \
                              fully-qualified path",
                         ),
-                        traits.iter().map(|trait_str| format!("<Example as {trait_str}>::{name}")),
+                        traits.iter().map(|trait_str| format!("<Example as {trait_str}>::")),
                         Applicability::HasPlaceholders,
+                        SuggestionStyle::ShowAlways,
                     );
                 }
                 ([type_str], []) => {
                     err.span_suggestion_verbose(
-                        span,
+                        sugg_sp,
                         format!(
-                            "if there were a trait named `Example` with associated {kind_str} `{name}` \
+                            "if there were a trait named `Example` with associated {kind_str} `{ident}` \
                              implemented for `{type_str}`, you could use the fully-qualified path",
                         ),
-                        format!("<{type_str} as Example>::{name}"),
+                        format!("<{type_str} as Example>::"),
                         Applicability::HasPlaceholders,
                     );
                 }
                 (types, []) => {
-                    err.span_suggestions(
-                        span,
+                    err.span_suggestions_with_style(
+                        sugg_sp,
                         format!(
-                            "if there were a trait named `Example` with associated {kind_str} `{name}` \
+                            "if there were a trait named `Example` with associated {kind_str} `{ident}` \
                              implemented for one of the types, you could use the fully-qualified \
                              path",
                         ),
                         types
                             .into_iter()
-                            .map(|type_str| format!("<{type_str} as Example>::{name}")),
+                            .map(|type_str| format!("<{type_str} as Example>::")),
                         Applicability::HasPlaceholders,
+                        SuggestionStyle::ShowAlways,
                     );
                 }
                 (types, traits) => {
                     let mut suggestions = vec![];
                     for type_str in types {
                         for trait_str in traits {
-                            suggestions.push(format!("<{type_str} as {trait_str}>::{name}"));
+                            suggestions.push(format!("<{type_str} as {trait_str}>::"));
                         }
                     }
-                    err.span_suggestions(
-                        span,
+                    err.span_suggestions_with_style(
+                        sugg_sp,
                         "use fully-qualified syntax",
                         suggestions,
                         Applicability::MachineApplicable,
+                        SuggestionStyle::ShowAlways,
                     );
                 }
             }
@@ -505,7 +677,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         err.emit()
     }
 
-    pub(crate) fn complain_about_ambiguous_inherent_assoc(
+    pub(crate) fn report_ambiguous_inherent_assoc_item(
         &self,
         name: Ident,
         candidates: Vec<DefId>,
@@ -518,12 +690,12 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             "multiple applicable items in scope"
         );
         err.span_label(name.span, format!("multiple `{name}` found"));
-        self.note_ambiguous_inherent_assoc_ty(&mut err, candidates, span);
+        self.note_ambiguous_inherent_assoc_item(&mut err, candidates, span);
         err.emit()
     }
 
     // FIXME(fmease): Heavily adapted from `rustc_hir_typeck::method::suggest`. Deduplicate.
-    fn note_ambiguous_inherent_assoc_ty(
+    fn note_ambiguous_inherent_assoc_item(
         &self,
         err: &mut Diag<'_>,
         candidates: Vec<DefId>,
@@ -566,7 +738,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
     }
 
     // FIXME(inherent_associated_types): Find similarly named associated types and suggest them.
-    pub(crate) fn complain_about_inherent_assoc_not_found(
+    pub(crate) fn report_unresolved_inherent_assoc_item(
         &self,
         name: Ident,
         self_ty: Ty<'tcx>,
@@ -1046,7 +1218,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         }
     }
 
-    pub fn report_prohibit_generics_error<'a>(
+    pub fn report_prohibited_generic_args<'a>(
         &self,
         segments: impl Iterator<Item = &'a hir::PathSegment<'a>> + Clone,
         args_visitors: impl Iterator<Item = &'a hir::GenericArg<'a>> + Clone,
@@ -1128,7 +1300,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         err.emit()
     }
 
-    pub fn report_trait_object_addition_traits_error(
+    pub fn report_trait_object_addition_traits(
         &self,
         regular_traits: &Vec<(ty::PolyTraitPredicate<'tcx>, SmallVec<[Span; 1]>)>,
     ) -> ErrorGuaranteed {
@@ -1171,7 +1343,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         err.emit()
     }
 
-    pub fn report_trait_object_with_no_traits_error(
+    pub fn report_trait_object_with_no_traits(
         &self,
         span: Span,
         user_written_clauses: impl IntoIterator<Item = (ty::Clause<'tcx>, Span)>,
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs
index 483b61add33..1f4692b19f1 100644
--- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs
+++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs
@@ -103,7 +103,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             // In case there is an associated type with the same name
             // Add the suggestion to this error
             if let Some(mut sugg) =
-                tcx.dcx().steal_non_err(self_ty.span, StashKey::AssociatedTypeSuggestion)
+                self.dcx().steal_non_err(self_ty.span, StashKey::AssociatedTypeSuggestion)
                 && let Suggestions::Enabled(ref mut s1) = diag.suggestions
                 && let Suggestions::Enabled(ref mut s2) = sugg.suggestions
             {
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
index 5e79e932015..6b21bbbfcd8 100644
--- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
+++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs
@@ -38,22 +38,20 @@ use rustc_middle::middle::stability::AllowUnstable;
 use rustc_middle::mir::interpret::LitToConstInput;
 use rustc_middle::ty::print::PrintPolyTraitRefExt as _;
 use rustc_middle::ty::{
-    self, AssocTag, Const, GenericArgKind, GenericArgsRef, GenericParamDefKind, ParamEnv, Ty,
-    TyCtxt, TypeVisitableExt, TypingMode, Upcast, fold_regions,
+    self, Const, GenericArgKind, GenericArgsRef, GenericParamDefKind, ParamEnv, Ty, TyCtxt,
+    TypeVisitableExt, TypingMode, Upcast, fold_regions,
 };
 use rustc_middle::{bug, span_bug};
 use rustc_session::lint::builtin::AMBIGUOUS_ASSOCIATED_ITEMS;
 use rustc_session::parse::feature_err;
-use rustc_span::edit_distance::find_best_match_for_name;
-use rustc_span::{DUMMY_SP, Ident, Span, Symbol, kw, sym};
+use rustc_span::{DUMMY_SP, Ident, Span, kw, sym};
 use rustc_trait_selection::infer::InferCtxtExt;
 use rustc_trait_selection::traits::wf::object_region_bounds;
 use rustc_trait_selection::traits::{self, ObligationCtxt};
 use tracing::{debug, instrument};
 
-use self::errors::assoc_tag_str;
 use crate::check::check_abi_fn_ptr;
-use crate::errors::{AmbiguousLifetimeBound, BadReturnTypeNotation, NoVariantNamed};
+use crate::errors::{AmbiguousLifetimeBound, BadReturnTypeNotation};
 use crate::hir_ty_lowering::errors::{GenericsArgsErrExtend, prohibit_assoc_item_constraint};
 use crate::hir_ty_lowering::generics::{check_generic_arg_count, lower_generic_args};
 use crate::middle::resolve_bound_vars as rbv;
@@ -150,7 +148,7 @@ pub trait HirTyLowerer<'tcx> {
         assoc_ident: Ident,
     ) -> ty::EarlyBinder<'tcx, &'tcx [(ty::Clause<'tcx>, Span)]>;
 
-    /// Lower an associated type/const (from a trait) to a projection.
+    /// Lower a path to an associated item (of a trait) to a projection.
     ///
     /// This method has to be defined by the concrete lowering context because
     /// dealing with higher-ranked trait references depends on its capabilities:
@@ -162,13 +160,12 @@ pub trait HirTyLowerer<'tcx> {
     ///
     /// The canonical example of this is associated type `T::P` where `T` is a type
     /// param constrained by `T: for<'a> Trait<'a>` and where `Trait` defines `P`.
-    fn lower_assoc_shared(
+    fn lower_assoc_item_path(
         &self,
         span: Span,
         item_def_id: DefId,
         item_segment: &hir::PathSegment<'tcx>,
         poly_trait_ref: ty::PolyTraitRef<'tcx>,
-        assoc_tag: ty::AssocTag,
     ) -> Result<(DefId, GenericArgsRef<'tcx>), ErrorGuaranteed>;
 
     fn lower_fn_sig(
@@ -245,39 +242,46 @@ pub enum FeedConstTy<'a, 'tcx> {
 }
 
 #[derive(Debug, Clone, Copy)]
-enum LowerAssocMode {
-    Type { permit_variants: bool },
+enum LowerTypeRelativePathMode {
+    Type(PermitVariants),
     Const,
 }
 
-impl LowerAssocMode {
+impl LowerTypeRelativePathMode {
     fn assoc_tag(self) -> ty::AssocTag {
         match self {
-            LowerAssocMode::Type { .. } => ty::AssocTag::Type,
-            LowerAssocMode::Const => ty::AssocTag::Const,
+            Self::Type(_) => ty::AssocTag::Type,
+            Self::Const => ty::AssocTag::Const,
         }
     }
 
     fn def_kind(self) -> DefKind {
         match self {
-            LowerAssocMode::Type { .. } => DefKind::AssocTy,
-            LowerAssocMode::Const => DefKind::AssocConst,
+            Self::Type(_) => DefKind::AssocTy,
+            Self::Const => DefKind::AssocConst,
         }
     }
 
-    fn permit_variants(self) -> bool {
+    fn permit_variants(self) -> PermitVariants {
         match self {
-            LowerAssocMode::Type { permit_variants } => permit_variants,
+            Self::Type(permit_variants) => permit_variants,
             // FIXME(mgca): Support paths like `Option::<T>::None` or `Option::<T>::Some` which
             // resolve to const ctors/fn items respectively.
-            LowerAssocMode::Const => false,
+            Self::Const => PermitVariants::No,
         }
     }
 }
 
+/// Whether to permit a path to resolve to an enum variant.
 #[derive(Debug, Clone, Copy)]
-enum LoweredAssoc<'tcx> {
-    Term(DefId, GenericArgsRef<'tcx>),
+pub enum PermitVariants {
+    Yes,
+    No,
+}
+
+#[derive(Debug, Clone, Copy)]
+enum TypeRelativePath<'tcx> {
+    AssocItem(DefId, GenericArgsRef<'tcx>),
     Variant { adt: Ty<'tcx>, variant_did: DefId },
 }
 
@@ -745,7 +749,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             trait_ref.path.segments.split_last().unwrap().1.iter(),
             GenericsArgsErrExtend::None,
         );
-        self.complain_about_internal_fn_trait(span, trait_def_id, trait_segment, false);
+        self.report_internal_fn_trait(span, trait_def_id, trait_segment, false);
 
         let (generic_args, arg_count) = self.lower_generic_args_of_path(
             trait_ref.path.span,
@@ -920,7 +924,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         trait_segment: &hir::PathSegment<'tcx>,
         is_impl: bool,
     ) -> ty::TraitRef<'tcx> {
-        self.complain_about_internal_fn_trait(span, trait_def_id, trait_segment, is_impl);
+        self.report_internal_fn_trait(span, trait_def_id, trait_segment, is_impl);
 
         let (generic_args, _) =
             self.lower_generic_args_of_path(span, trait_def_id, &[], trait_segment, Some(self_ty));
@@ -933,7 +937,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
     fn probe_trait_that_defines_assoc_item(
         &self,
         trait_def_id: DefId,
-        assoc_tag: AssocTag,
+        assoc_tag: ty::AssocTag,
         assoc_ident: Ident,
     ) -> bool {
         self.tcx()
@@ -976,7 +980,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         &self,
         ty_param_def_id: LocalDefId,
         ty_param_span: Span,
-        assoc_tag: AssocTag,
+        assoc_tag: ty::AssocTag,
         assoc_ident: Ident,
         span: Span,
     ) -> Result<ty::PolyTraitRef<'tcx>, ErrorGuaranteed> {
@@ -1011,7 +1015,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         &self,
         all_candidates: impl Fn() -> I,
         qself: AssocItemQSelf,
-        assoc_tag: AssocTag,
+        assoc_tag: ty::AssocTag,
         assoc_ident: Ident,
         span: Span,
         constraint: Option<&hir::AssocItemConstraint<'tcx>>,
@@ -1026,15 +1030,14 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         });
 
         let Some(bound) = matching_candidates.next() else {
-            let reported = self.complain_about_assoc_item_not_found(
+            return Err(self.report_unresolved_assoc_item(
                 all_candidates,
                 qself,
                 assoc_tag,
                 assoc_ident,
                 span,
                 constraint,
-            );
-            return Err(reported);
+            ));
         };
         debug!(?bound);
 
@@ -1127,7 +1130,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         Ok(bound)
     }
 
-    /// Lower a [type-relative] path referring to an associated type or to an enum variant.
+    /// Lower a [type-relative](hir::QPath::TypeRelative) path in type position to a type.
     ///
     /// If the path refers to an enum variant and `permit_variants` holds,
     /// the returned type is simply the provided self type `qself_ty`.
@@ -1148,61 +1151,63 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
     /// described in the previous paragraph and their modeling of projections would likely be
     /// very similar in nature.
     ///
-    /// [type-relative]: hir::QPath::TypeRelative
     /// [#22519]: https://github.com/rust-lang/rust/issues/22519
     /// [iat]: https://github.com/rust-lang/rust/issues/8995#issuecomment-1569208403
     //
     // NOTE: When this function starts resolving `Trait::AssocTy` successfully
     // it should also start reporting the `BARE_TRAIT_OBJECTS` lint.
     #[instrument(level = "debug", skip_all, ret)]
-    pub fn lower_assoc_path_ty(
+    pub fn lower_type_relative_ty_path(
         &self,
-        hir_ref_id: HirId,
+        self_ty: Ty<'tcx>,
+        hir_self_ty: &'tcx hir::Ty<'tcx>,
+        segment: &'tcx hir::PathSegment<'tcx>,
+        qpath_hir_id: HirId,
         span: Span,
-        qself_ty: Ty<'tcx>,
-        qself: &'tcx hir::Ty<'tcx>,
-        assoc_segment: &'tcx hir::PathSegment<'tcx>,
-        permit_variants: bool,
+        permit_variants: PermitVariants,
     ) -> Result<(Ty<'tcx>, DefKind, DefId), ErrorGuaranteed> {
         let tcx = self.tcx();
-        match self.lower_assoc_path_shared(
-            hir_ref_id,
+        match self.lower_type_relative_path(
+            self_ty,
+            hir_self_ty,
+            segment,
+            qpath_hir_id,
             span,
-            qself_ty,
-            qself,
-            assoc_segment,
-            LowerAssocMode::Type { permit_variants },
+            LowerTypeRelativePathMode::Type(permit_variants),
         )? {
-            LoweredAssoc::Term(def_id, args) => {
+            TypeRelativePath::AssocItem(def_id, args) => {
                 let alias_ty = ty::AliasTy::new_from_args(tcx, def_id, args);
                 let ty = Ty::new_alias(tcx, alias_ty.kind(tcx), alias_ty);
                 Ok((ty, tcx.def_kind(def_id), def_id))
             }
-            LoweredAssoc::Variant { adt, variant_did } => Ok((adt, DefKind::Variant, variant_did)),
+            TypeRelativePath::Variant { adt, variant_did } => {
+                Ok((adt, DefKind::Variant, variant_did))
+            }
         }
     }
 
+    /// Lower a [type-relative][hir::QPath::TypeRelative] path to a (type-level) constant.
     #[instrument(level = "debug", skip_all, ret)]
-    fn lower_assoc_path_const(
+    fn lower_type_relative_const_path(
         &self,
-        hir_ref_id: HirId,
+        self_ty: Ty<'tcx>,
+        hir_self_ty: &'tcx hir::Ty<'tcx>,
+        segment: &'tcx hir::PathSegment<'tcx>,
+        qpath_hir_id: HirId,
         span: Span,
-        qself_ty: Ty<'tcx>,
-        qself: &'tcx hir::Ty<'tcx>,
-        assoc_segment: &'tcx hir::PathSegment<'tcx>,
     ) -> Result<Const<'tcx>, ErrorGuaranteed> {
         let tcx = self.tcx();
-        let (def_id, args) = match self.lower_assoc_path_shared(
-            hir_ref_id,
+        let (def_id, args) = match self.lower_type_relative_path(
+            self_ty,
+            hir_self_ty,
+            segment,
+            qpath_hir_id,
             span,
-            qself_ty,
-            qself,
-            assoc_segment,
-            LowerAssocMode::Const,
+            LowerTypeRelativePathMode::Const,
         )? {
-            LoweredAssoc::Term(def_id, args) => {
+            TypeRelativePath::AssocItem(def_id, args) => {
                 if !tcx.associated_item(def_id).is_type_const_capable(tcx) {
-                    let mut err = tcx.dcx().struct_span_err(
+                    let mut err = self.dcx().struct_span_err(
                         span,
                         "use of trait associated const without `#[type_const]`",
                     );
@@ -1213,75 +1218,134 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             }
             // FIXME(mgca): implement support for this once ready to support all adt ctor expressions,
             // not just const ctors
-            LoweredAssoc::Variant { .. } => {
+            TypeRelativePath::Variant { .. } => {
                 span_bug!(span, "unexpected variant res for type associated const path")
             }
         };
         Ok(Const::new_unevaluated(tcx, ty::UnevaluatedConst::new(def_id, args)))
     }
 
+    /// Lower a [type-relative][hir::QPath::TypeRelative] (and type-level) path.
     #[instrument(level = "debug", skip_all, ret)]
-    fn lower_assoc_path_shared(
+    fn lower_type_relative_path(
         &self,
-        hir_ref_id: HirId,
+        self_ty: Ty<'tcx>,
+        hir_self_ty: &'tcx hir::Ty<'tcx>,
+        segment: &'tcx hir::PathSegment<'tcx>,
+        qpath_hir_id: HirId,
         span: Span,
-        qself_ty: Ty<'tcx>,
-        qself: &'tcx hir::Ty<'tcx>,
-        assoc_segment: &'tcx hir::PathSegment<'tcx>,
-        mode: LowerAssocMode,
-    ) -> Result<LoweredAssoc<'tcx>, ErrorGuaranteed> {
-        debug!(%qself_ty, ?assoc_segment.ident);
+        mode: LowerTypeRelativePathMode,
+    ) -> Result<TypeRelativePath<'tcx>, ErrorGuaranteed> {
+        debug!(%self_ty, ?segment.ident);
         let tcx = self.tcx();
 
-        let assoc_ident = assoc_segment.ident;
-
         // Check if we have an enum variant or an inherent associated type.
-        let mut variant_resolution = None;
-        if let Some(adt_def) = self.probe_adt(span, qself_ty) {
+        let mut variant_def_id = None;
+        if let Some(adt_def) = self.probe_adt(span, self_ty) {
             if adt_def.is_enum() {
                 let variant_def = adt_def
                     .variants()
                     .iter()
-                    .find(|vd| tcx.hygienic_eq(assoc_ident, vd.ident(tcx), adt_def.did()));
+                    .find(|vd| tcx.hygienic_eq(segment.ident, vd.ident(tcx), adt_def.did()));
                 if let Some(variant_def) = variant_def {
-                    if mode.permit_variants() {
-                        tcx.check_stability(variant_def.def_id, Some(hir_ref_id), span, None);
+                    if let PermitVariants::Yes = mode.permit_variants() {
+                        tcx.check_stability(variant_def.def_id, Some(qpath_hir_id), span, None);
                         let _ = self.prohibit_generic_args(
-                            slice::from_ref(assoc_segment).iter(),
-                            GenericsArgsErrExtend::EnumVariant { qself, assoc_segment, adt_def },
+                            slice::from_ref(segment).iter(),
+                            GenericsArgsErrExtend::EnumVariant {
+                                qself: hir_self_ty,
+                                assoc_segment: segment,
+                                adt_def,
+                            },
                         );
-                        return Ok(LoweredAssoc::Variant {
-                            adt: qself_ty,
+                        return Ok(TypeRelativePath::Variant {
+                            adt: self_ty,
                             variant_did: variant_def.def_id,
                         });
                     } else {
-                        variant_resolution = Some(variant_def.def_id);
+                        variant_def_id = Some(variant_def.def_id);
                     }
                 }
             }
 
             // FIXME(inherent_associated_types, #106719): Support self types other than ADTs.
-            if let Some((did, args)) = self.probe_inherent_assoc_shared(
-                assoc_segment,
+            if let Some((did, args)) = self.probe_inherent_assoc_item(
+                segment,
                 adt_def.did(),
-                qself_ty,
-                hir_ref_id,
+                self_ty,
+                qpath_hir_id,
                 span,
                 mode.assoc_tag(),
             )? {
-                return Ok(LoweredAssoc::Term(did, args));
+                return Ok(TypeRelativePath::AssocItem(did, args));
             }
         }
 
-        let qself_res = if let hir::TyKind::Path(hir::QPath::Resolved(_, path)) = &qself.kind {
-            path.res
-        } else {
-            Res::Err
+        let (item_def_id, bound) = self.resolve_type_relative_path(
+            self_ty,
+            hir_self_ty,
+            mode.assoc_tag(),
+            segment,
+            qpath_hir_id,
+            span,
+            variant_def_id,
+        )?;
+
+        let (item_def_id, args) = self.lower_assoc_item_path(span, item_def_id, segment, bound)?;
+
+        if let Some(variant_def_id) = variant_def_id {
+            tcx.node_span_lint(AMBIGUOUS_ASSOCIATED_ITEMS, qpath_hir_id, span, |lint| {
+                lint.primary_message("ambiguous associated item");
+                let mut could_refer_to = |kind: DefKind, def_id, also| {
+                    let note_msg = format!(
+                        "`{}` could{} refer to the {} defined here",
+                        segment.ident,
+                        also,
+                        tcx.def_kind_descr(kind, def_id)
+                    );
+                    lint.span_note(tcx.def_span(def_id), note_msg);
+                };
+
+                could_refer_to(DefKind::Variant, variant_def_id, "");
+                could_refer_to(mode.def_kind(), item_def_id, " also");
+
+                lint.span_suggestion(
+                    span,
+                    "use fully-qualified syntax",
+                    format!(
+                        "<{} as {}>::{}",
+                        self_ty,
+                        tcx.item_name(bound.def_id()),
+                        segment.ident
+                    ),
+                    Applicability::MachineApplicable,
+                );
+            });
+        }
+
+        Ok(TypeRelativePath::AssocItem(item_def_id, args))
+    }
+
+    /// Resolve a [type-relative](hir::QPath::TypeRelative) (and type-level) path.
+    fn resolve_type_relative_path(
+        &self,
+        self_ty: Ty<'tcx>,
+        hir_self_ty: &'tcx hir::Ty<'tcx>,
+        assoc_tag: ty::AssocTag,
+        segment: &'tcx hir::PathSegment<'tcx>,
+        qpath_hir_id: HirId,
+        span: Span,
+        variant_def_id: Option<DefId>,
+    ) -> Result<(DefId, ty::PolyTraitRef<'tcx>), ErrorGuaranteed> {
+        let tcx = self.tcx();
+
+        let self_ty_res = match hir_self_ty.kind {
+            hir::TyKind::Path(hir::QPath::Resolved(_, path)) => path.res,
+            _ => Res::Err,
         };
 
-        // Find the type of the associated item, and the trait where the associated
-        // item is declared.
-        let bound = match (qself_ty.kind(), qself_res) {
+        // Find the type of the assoc item, and the trait where the associated item is declared.
+        let bound = match (self_ty.kind(), self_ty_res) {
             (_, Res::SelfTyAlias { alias_to: impl_def_id, is_trait_impl: true, .. }) => {
                 // `Self` in an impl of a trait -- we have a concrete self type and a
                 // trait reference.
@@ -1292,14 +1356,12 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
 
                 self.probe_single_bound_for_assoc_item(
                     || {
-                        traits::supertraits(
-                            tcx,
-                            ty::Binder::dummy(trait_ref.instantiate_identity()),
-                        )
+                        let trait_ref = ty::Binder::dummy(trait_ref.instantiate_identity());
+                        traits::supertraits(tcx, trait_ref)
                     },
                     AssocItemQSelf::SelfTyAlias,
-                    mode.assoc_tag(),
-                    assoc_ident,
+                    assoc_tag,
+                    segment.ident,
                     span,
                     None,
                 )?
@@ -1309,167 +1371,33 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 Res::SelfTyParam { trait_: param_did } | Res::Def(DefKind::TyParam, param_did),
             ) => self.probe_single_ty_param_bound_for_assoc_item(
                 param_did.expect_local(),
-                qself.span,
-                mode.assoc_tag(),
-                assoc_ident,
+                hir_self_ty.span,
+                assoc_tag,
+                segment.ident,
                 span,
             )?,
             _ => {
-                let kind_str = assoc_tag_str(mode.assoc_tag());
-                let reported = if variant_resolution.is_some() {
-                    // Variant in type position
-                    let msg = format!("expected {kind_str}, found variant `{assoc_ident}`");
-                    self.dcx().span_err(span, msg)
-                } else if qself_ty.is_enum() {
-                    let mut err = self.dcx().create_err(NoVariantNamed {
-                        span: assoc_ident.span,
-                        ident: assoc_ident,
-                        ty: qself_ty,
-                    });
-
-                    let adt_def = qself_ty.ty_adt_def().expect("enum is not an ADT");
-                    if let Some(variant_name) = find_best_match_for_name(
-                        &adt_def
-                            .variants()
-                            .iter()
-                            .map(|variant| variant.name)
-                            .collect::<Vec<Symbol>>(),
-                        assoc_ident.name,
-                        None,
-                    ) && let Some(variant) =
-                        adt_def.variants().iter().find(|s| s.name == variant_name)
-                    {
-                        let mut suggestion = vec![(assoc_ident.span, variant_name.to_string())];
-                        if let hir::Node::Stmt(&hir::Stmt {
-                            kind: hir::StmtKind::Semi(expr), ..
-                        })
-                        | hir::Node::Expr(expr) = tcx.parent_hir_node(hir_ref_id)
-                            && let hir::ExprKind::Struct(..) = expr.kind
-                        {
-                            match variant.ctor {
-                                None => {
-                                    // struct
-                                    suggestion = vec![(
-                                        assoc_ident.span.with_hi(expr.span.hi()),
-                                        if variant.fields.is_empty() {
-                                            format!("{variant_name} {{}}")
-                                        } else {
-                                            format!(
-                                                "{variant_name} {{ {} }}",
-                                                variant
-                                                    .fields
-                                                    .iter()
-                                                    .map(|f| format!("{}: /* value */", f.name))
-                                                    .collect::<Vec<_>>()
-                                                    .join(", ")
-                                            )
-                                        },
-                                    )];
-                                }
-                                Some((hir::def::CtorKind::Fn, def_id)) => {
-                                    // tuple
-                                    let fn_sig = tcx.fn_sig(def_id).instantiate_identity();
-                                    let inputs = fn_sig.inputs().skip_binder();
-                                    suggestion = vec![(
-                                        assoc_ident.span.with_hi(expr.span.hi()),
-                                        format!(
-                                            "{variant_name}({})",
-                                            inputs
-                                                .iter()
-                                                .map(|i| format!("/* {i} */"))
-                                                .collect::<Vec<_>>()
-                                                .join(", ")
-                                        ),
-                                    )];
-                                }
-                                Some((hir::def::CtorKind::Const, _)) => {
-                                    // unit
-                                    suggestion = vec![(
-                                        assoc_ident.span.with_hi(expr.span.hi()),
-                                        variant_name.to_string(),
-                                    )];
-                                }
-                            }
-                        }
-                        err.multipart_suggestion_verbose(
-                            "there is a variant with a similar name",
-                            suggestion,
-                            Applicability::HasPlaceholders,
-                        );
-                    } else {
-                        err.span_label(
-                            assoc_ident.span,
-                            format!("variant not found in `{qself_ty}`"),
-                        );
-                    }
-
-                    if let Some(sp) = tcx.hir_span_if_local(adt_def.did()) {
-                        err.span_label(sp, format!("variant `{assoc_ident}` not found here"));
-                    }
-
-                    err.emit()
-                } else if let Err(reported) = qself_ty.error_reported() {
-                    reported
-                } else {
-                    self.maybe_report_similar_assoc_fn(span, qself_ty, qself)?;
-
-                    let traits: Vec<_> =
-                        self.probe_traits_that_match_assoc_ty(qself_ty, assoc_ident);
-
-                    // Don't print `ty::Error` to the user.
-                    self.report_ambiguous_assoc(
-                        span,
-                        &[qself_ty.to_string()],
-                        &traits,
-                        assoc_ident.name,
-                        mode.assoc_tag(),
-                    )
-                };
-                return Err(reported);
+                return Err(self.report_unresolved_type_relative_path(
+                    self_ty,
+                    hir_self_ty,
+                    assoc_tag,
+                    segment.ident,
+                    qpath_hir_id,
+                    span,
+                    variant_def_id,
+                ));
             }
         };
 
-        let trait_did = bound.def_id();
         let assoc_item = self
-            .probe_assoc_item(assoc_ident, mode.assoc_tag(), hir_ref_id, span, trait_did)
+            .probe_assoc_item(segment.ident, assoc_tag, qpath_hir_id, span, bound.def_id())
             .expect("failed to find associated item");
-        let (def_id, args) = self.lower_assoc_shared(
-            span,
-            assoc_item.def_id,
-            assoc_segment,
-            bound,
-            mode.assoc_tag(),
-        )?;
-        let result = LoweredAssoc::Term(def_id, args);
-
-        if let Some(variant_def_id) = variant_resolution {
-            tcx.node_span_lint(AMBIGUOUS_ASSOCIATED_ITEMS, hir_ref_id, span, |lint| {
-                lint.primary_message("ambiguous associated item");
-                let mut could_refer_to = |kind: DefKind, def_id, also| {
-                    let note_msg = format!(
-                        "`{}` could{} refer to the {} defined here",
-                        assoc_ident,
-                        also,
-                        tcx.def_kind_descr(kind, def_id)
-                    );
-                    lint.span_note(tcx.def_span(def_id), note_msg);
-                };
 
-                could_refer_to(DefKind::Variant, variant_def_id, "");
-                could_refer_to(mode.def_kind(), assoc_item.def_id, " also");
-
-                lint.span_suggestion(
-                    span,
-                    "use fully-qualified syntax",
-                    format!("<{} as {}>::{}", qself_ty, tcx.item_name(trait_did), assoc_ident),
-                    Applicability::MachineApplicable,
-                );
-            });
-        }
-        Ok(result)
+        Ok((assoc_item.def_id, bound))
     }
 
-    fn probe_inherent_assoc_shared(
+    /// Search for inherent associated items for use at the type level.
+    fn probe_inherent_assoc_item(
         &self,
         segment: &hir::PathSegment<'tcx>,
         adt_did: DefId,
@@ -1624,7 +1552,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             .collect();
 
         match &applicable_candidates[..] {
-            &[] => Err(self.complain_about_inherent_assoc_not_found(
+            &[] => Err(self.report_unresolved_inherent_assoc_item(
                 name,
                 self_ty,
                 candidates,
@@ -1635,7 +1563,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
 
             &[applicable_candidate] => Ok(applicable_candidate),
 
-            &[_, ..] => Err(self.complain_about_ambiguous_inherent_assoc(
+            &[_, ..] => Err(self.report_ambiguous_inherent_assoc_item(
                 name,
                 applicable_candidates.into_iter().map(|(_, (candidate, _))| candidate).collect(),
                 span,
@@ -1763,9 +1691,9 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             .collect()
     }
 
-    /// Lower a qualified path to a type.
+    /// Lower a [resolved][hir::QPath::Resolved] associated type path to a projection.
     #[instrument(level = "debug", skip_all)]
-    fn lower_qpath_ty(
+    fn lower_resolved_assoc_ty_path(
         &self,
         span: Span,
         opt_self_ty: Option<Ty<'tcx>>,
@@ -1773,7 +1701,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         trait_segment: Option<&hir::PathSegment<'tcx>>,
         item_segment: &hir::PathSegment<'tcx>,
     ) -> Ty<'tcx> {
-        match self.lower_qpath_shared(
+        match self.lower_resolved_assoc_item_path(
             span,
             opt_self_ty,
             item_def_id,
@@ -1788,9 +1716,9 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         }
     }
 
-    /// Lower a qualified path to a const.
+    /// Lower a [resolved][hir::QPath::Resolved] associated const path to a (type-level) constant.
     #[instrument(level = "debug", skip_all)]
-    fn lower_qpath_const(
+    fn lower_resolved_assoc_const_path(
         &self,
         span: Span,
         opt_self_ty: Option<Ty<'tcx>>,
@@ -1798,7 +1726,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         trait_segment: Option<&hir::PathSegment<'tcx>>,
         item_segment: &hir::PathSegment<'tcx>,
     ) -> Const<'tcx> {
-        match self.lower_qpath_shared(
+        match self.lower_resolved_assoc_item_path(
             span,
             opt_self_ty,
             item_def_id,
@@ -1814,8 +1742,9 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         }
     }
 
+    /// Lower a [resolved][hir::QPath::Resolved] (type-level) associated item path.
     #[instrument(level = "debug", skip_all)]
-    fn lower_qpath_shared(
+    fn lower_resolved_assoc_item_path(
         &self,
         span: Span,
         opt_self_ty: Option<Ty<'tcx>>,
@@ -1830,7 +1759,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         debug!(?trait_def_id);
 
         let Some(self_ty) = opt_self_ty else {
-            return Err(self.error_missing_qpath_self_ty(
+            return Err(self.report_missing_self_ty_for_resolved_path(
                 trait_def_id,
                 span,
                 item_segment,
@@ -1849,57 +1778,6 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         Ok((item_def_id, item_args))
     }
 
-    fn error_missing_qpath_self_ty(
-        &self,
-        trait_def_id: DefId,
-        span: Span,
-        item_segment: &hir::PathSegment<'tcx>,
-        assoc_tag: ty::AssocTag,
-    ) -> ErrorGuaranteed {
-        let tcx = self.tcx();
-        let path_str = tcx.def_path_str(trait_def_id);
-
-        let def_id = self.item_def_id();
-        debug!(item_def_id = ?def_id);
-
-        // FIXME: document why/how this is different from `tcx.local_parent(def_id)`
-        let parent_def_id = tcx.hir_get_parent_item(tcx.local_def_id_to_hir_id(def_id)).to_def_id();
-        debug!(?parent_def_id);
-
-        // If the trait in segment is the same as the trait defining the item,
-        // use the `<Self as ..>` syntax in the error.
-        let is_part_of_self_trait_constraints = def_id.to_def_id() == trait_def_id;
-        let is_part_of_fn_in_self_trait = parent_def_id == trait_def_id;
-
-        let type_names = if is_part_of_self_trait_constraints || is_part_of_fn_in_self_trait {
-            vec!["Self".to_string()]
-        } else {
-            // Find all the types that have an `impl` for the trait.
-            tcx.all_impls(trait_def_id)
-                .filter_map(|impl_def_id| tcx.impl_trait_header(impl_def_id))
-                .filter(|header| {
-                    // Consider only accessible traits
-                    tcx.visibility(trait_def_id).is_accessible_from(self.item_def_id(), tcx)
-                        && header.polarity != ty::ImplPolarity::Negative
-                })
-                .map(|header| header.trait_ref.instantiate_identity().self_ty())
-                // We don't care about blanket impls.
-                .filter(|self_ty| !self_ty.has_non_region_param())
-                .map(|self_ty| tcx.erase_regions(self_ty).to_string())
-                .collect()
-        };
-        // FIXME: also look at `tcx.generics_of(self.item_def_id()).params` any that
-        // references the trait. Relevant for the first case in
-        // `src/test/ui/associated-types/associated-types-in-ambiguous-context.rs`
-        self.report_ambiguous_assoc(
-            span,
-            &type_names,
-            &[path_str],
-            item_segment.ident.name,
-            assoc_tag,
-        )
-    }
-
     pub fn prohibit_generic_args<'a>(
         &self,
         segments: impl Iterator<Item = &'a hir::PathSegment<'a>> + Clone,
@@ -1908,7 +1786,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         let args_visitors = segments.clone().flat_map(|segment| segment.args().args);
         let mut result = Ok(());
         if let Some(_) = args_visitors.clone().next() {
-            result = Err(self.report_prohibit_generics_error(
+            result = Err(self.report_prohibited_generic_args(
                 segments.clone(),
                 args_visitors,
                 err_extend,
@@ -2069,14 +1947,14 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         generic_segments
     }
 
-    /// Lower a type `Path` to a type.
+    /// Lower a [resolved][hir::QPath::Resolved] path to a type.
     #[instrument(level = "debug", skip_all)]
-    pub fn lower_path(
+    pub fn lower_resolved_ty_path(
         &self,
         opt_self_ty: Option<Ty<'tcx>>,
         path: &hir::Path<'tcx>,
         hir_id: HirId,
-        permit_variants: bool,
+        permit_variants: PermitVariants,
     ) -> Ty<'tcx> {
         debug!(?path.res, ?opt_self_ty, ?path.segments);
         let tcx = self.tcx();
@@ -2107,7 +1985,9 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 );
                 self.lower_path_segment(span, did, path.segments.last().unwrap())
             }
-            Res::Def(kind @ DefKind::Variant, def_id) if permit_variants => {
+            Res::Def(kind @ DefKind::Variant, def_id)
+                if let PermitVariants::Yes = permit_variants =>
+            {
                 // Lower "variant type" as if it were a real type.
                 // The resulting `Ty` is type of the variant's enum for now.
                 assert_eq!(opt_self_ty, None);
@@ -2202,7 +2082,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 } else {
                     None
                 };
-                self.lower_qpath_ty(
+                self.lower_resolved_assoc_ty_path(
                     span,
                     opt_self_ty,
                     def_id,
@@ -2298,7 +2178,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         }
     }
 
-    /// Convert a [`hir::ConstArg`] to a [`ty::Const`](Const).
+    /// Lower a [`hir::ConstArg`] to a (type-level) [`ty::Const`](Const).
     #[instrument(skip(self), level = "debug")]
     pub fn lower_const_arg(
         &self,
@@ -2323,7 +2203,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             if tcx.features().generic_const_parameter_types()
                 && (anon_const_type.has_free_regions() || anon_const_type.has_erased_regions())
             {
-                let e = tcx.dcx().span_err(
+                let e = self.dcx().span_err(
                     const_arg.span(),
                     "anonymous constants with lifetimes in their type are not yet supported",
                 );
@@ -2334,7 +2214,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             // use this type to feed the `type_of` and query results must not contain inference
             // variables otherwise we will ICE.
             if anon_const_type.has_non_region_infer() {
-                let e = tcx.dcx().span_err(
+                let e = self.dcx().span_err(
                     const_arg.span(),
                     "anonymous constants with inferred types are not yet supported",
                 );
@@ -2344,7 +2224,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             // We error when the type contains unsubstituted generics since we do not currently
             // give the anon const any of the generics from the parent.
             if anon_const_type.has_non_region_param() {
-                let e = tcx.dcx().span_err(
+                let e = self.dcx().span_err(
                     const_arg.span(),
                     "anonymous constants referencing generics are not yet supported",
                 );
@@ -2363,13 +2243,19 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             hir::ConstArgKind::Path(hir::QPath::Resolved(maybe_qself, path)) => {
                 debug!(?maybe_qself, ?path);
                 let opt_self_ty = maybe_qself.as_ref().map(|qself| self.lower_ty(qself));
-                self.lower_const_path_resolved(opt_self_ty, path, hir_id)
+                self.lower_resolved_const_path(opt_self_ty, path, hir_id)
             }
-            hir::ConstArgKind::Path(hir::QPath::TypeRelative(qself, segment)) => {
-                debug!(?qself, ?segment);
-                let ty = self.lower_ty(qself);
-                self.lower_assoc_path_const(hir_id, const_arg.span(), ty, qself, segment)
-                    .unwrap_or_else(|guar| Const::new_error(tcx, guar))
+            hir::ConstArgKind::Path(hir::QPath::TypeRelative(hir_self_ty, segment)) => {
+                debug!(?hir_self_ty, ?segment);
+                let self_ty = self.lower_ty(hir_self_ty);
+                self.lower_type_relative_const_path(
+                    self_ty,
+                    hir_self_ty,
+                    segment,
+                    hir_id,
+                    const_arg.span(),
+                )
+                .unwrap_or_else(|guar| Const::new_error(tcx, guar))
             }
             hir::ConstArgKind::Path(qpath @ hir::QPath::LangItem(..)) => {
                 ty::Const::new_error_with_message(
@@ -2383,7 +2269,8 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         }
     }
 
-    fn lower_const_path_resolved(
+    /// Lower a [resolved][hir::QPath::Resolved] path to a (type-level) constant.
+    fn lower_resolved_const_path(
         &self,
         opt_self_ty: Option<Ty<'tcx>>,
         path: &hir::Path<'tcx>,
@@ -2420,7 +2307,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 } else {
                     None
                 };
-                self.lower_qpath_const(
+                self.lower_resolved_assoc_const_path(
                     span,
                     opt_self_ty,
                     did,
@@ -2630,7 +2517,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
             hir::TyKind::Path(hir::QPath::Resolved(maybe_qself, path)) => {
                 debug!(?maybe_qself, ?path);
                 let opt_self_ty = maybe_qself.as_ref().map(|qself| self.lower_ty(qself));
-                self.lower_path(opt_self_ty, path, hir_ty.hir_id, false)
+                self.lower_resolved_ty_path(opt_self_ty, path, hir_ty.hir_id, PermitVariants::No)
             }
             &hir::TyKind::OpaqueDef(opaque_ty) => {
                 // If this is an RPITIT and we are using the new RPITIT lowering scheme, we
@@ -2684,12 +2571,19 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 let guar = self.dcx().emit_err(BadReturnTypeNotation { span: hir_ty.span });
                 Ty::new_error(tcx, guar)
             }
-            hir::TyKind::Path(hir::QPath::TypeRelative(qself, segment)) => {
-                debug!(?qself, ?segment);
-                let ty = self.lower_ty(qself);
-                self.lower_assoc_path_ty(hir_ty.hir_id, hir_ty.span, ty, qself, segment, false)
-                    .map(|(ty, _, _)| ty)
-                    .unwrap_or_else(|guar| Ty::new_error(tcx, guar))
+            hir::TyKind::Path(hir::QPath::TypeRelative(hir_self_ty, segment)) => {
+                debug!(?hir_self_ty, ?segment);
+                let self_ty = self.lower_ty(hir_self_ty);
+                self.lower_type_relative_ty_path(
+                    self_ty,
+                    hir_self_ty,
+                    segment,
+                    hir_ty.hir_id,
+                    hir_ty.span,
+                    PermitVariants::No,
+                )
+                .map(|(ty, _, _)| ty)
+                .unwrap_or_else(|guar| Ty::new_error(tcx, guar))
             }
             &hir::TyKind::Path(hir::QPath::LangItem(lang_item, span)) => {
                 let def_id = tcx.require_lang_item(lang_item, Some(span));
diff --git a/compiler/rustc_hir_typeck/src/coercion.rs b/compiler/rustc_hir_typeck/src/coercion.rs
index 9c07f97a734..4f77594deca 100644
--- a/compiler/rustc_hir_typeck/src/coercion.rs
+++ b/compiler/rustc_hir_typeck/src/coercion.rs
@@ -1854,17 +1854,16 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
             fcx.err_ctxt().report_mismatched_types(cause, fcx.param_env, expected, found, ty_err);
 
         let due_to_block = matches!(fcx.tcx.hir_node(block_or_return_id), hir::Node::Block(..));
-
-        let parent_id = fcx.tcx.parent_hir_id(block_or_return_id);
-        let parent = fcx.tcx.hir_node(parent_id);
+        let parent = fcx.tcx.parent_hir_node(block_or_return_id);
         if let Some(expr) = expression
             && let hir::Node::Expr(&hir::Expr {
                 kind: hir::ExprKind::Closure(&hir::Closure { body, .. }),
                 ..
             }) = parent
-            && !matches!(fcx.tcx.hir_body(body).value.kind, hir::ExprKind::Block(..))
         {
-            fcx.suggest_missing_semicolon(&mut err, expr, expected, true);
+            let needs_block =
+                !matches!(fcx.tcx.hir_body(body).value.kind, hir::ExprKind::Block(..));
+            fcx.suggest_missing_semicolon(&mut err, expr, expected, needs_block, true);
         }
         // Verify that this is a tail expression of a function, otherwise the
         // label pointing out the cause for the type coercion will be wrong
@@ -1872,7 +1871,7 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
         if let Some(expr) = expression
             && due_to_block
         {
-            fcx.suggest_missing_semicolon(&mut err, expr, expected, false);
+            fcx.suggest_missing_semicolon(&mut err, expr, expected, false, false);
             let pointing_at_return_type = fcx.suggest_mismatched_types_on_tail(
                 &mut err,
                 expr,
diff --git a/compiler/rustc_hir_typeck/src/expr.rs b/compiler/rustc_hir_typeck/src/expr.rs
index a1a33885b94..1d86f7d223c 100644
--- a/compiler/rustc_hir_typeck/src/expr.rs
+++ b/compiler/rustc_hir_typeck/src/expr.rs
@@ -911,7 +911,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         self,
                         &cause,
                         |mut err| {
-                            self.suggest_missing_semicolon(&mut err, expr, e_ty, false);
+                            self.suggest_missing_semicolon(&mut err, expr, e_ty, false, false);
                             self.suggest_mismatched_types_on_tail(
                                 &mut err, expr, ty, e_ty, target_id,
                             );
@@ -1900,62 +1900,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // We defer checking whether the element type is `Copy` as it is possible to have
         // an inference variable as a repeat count and it seems unlikely that `Copy` would
         // have inference side effects required for type checking to succeed.
-        if tcx.features().generic_arg_infer() {
-            self.deferred_repeat_expr_checks.borrow_mut().push((element, element_ty, count));
-        // If the length is 0, we don't create any elements, so we don't copy any.
-        // If the length is 1, we don't copy that one element, we move it. Only check
-        // for `Copy` if the length is larger, or unevaluated.
-        } else if count.try_to_target_usize(self.tcx).is_none_or(|x| x > 1) {
-            self.enforce_repeat_element_needs_copy_bound(element, element_ty);
-        }
+        self.deferred_repeat_expr_checks.borrow_mut().push((element, element_ty, count));
 
         let ty = Ty::new_array_with_const_len(tcx, t, count);
         self.register_wf_obligation(ty.into(), expr.span, ObligationCauseCode::WellFormed(None));
         ty
     }
 
-    /// Requires that `element_ty` is `Copy` (unless it's a const expression itself).
-    pub(super) fn enforce_repeat_element_needs_copy_bound(
-        &self,
-        element: &hir::Expr<'_>,
-        element_ty: Ty<'tcx>,
-    ) {
-        let tcx = self.tcx;
-        // Actual constants as the repeat element get inserted repeatedly instead of getting copied via Copy.
-        match &element.kind {
-            hir::ExprKind::ConstBlock(..) => return,
-            hir::ExprKind::Path(qpath) => {
-                let res = self.typeck_results.borrow().qpath_res(qpath, element.hir_id);
-                if let Res::Def(DefKind::Const | DefKind::AssocConst | DefKind::AnonConst, _) = res
-                {
-                    return;
-                }
-            }
-            _ => {}
-        }
-        // If someone calls a const fn or constructs a const value, they can extract that
-        // out into a separate constant (or a const block in the future), so we check that
-        // to tell them that in the diagnostic. Does not affect typeck.
-        let is_constable = match element.kind {
-            hir::ExprKind::Call(func, _args) => match *self.node_ty(func.hir_id).kind() {
-                ty::FnDef(def_id, _) if tcx.is_stable_const_fn(def_id) => traits::IsConstable::Fn,
-                _ => traits::IsConstable::No,
-            },
-            hir::ExprKind::Path(qpath) => {
-                match self.typeck_results.borrow().qpath_res(&qpath, element.hir_id) {
-                    Res::Def(DefKind::Ctor(_, CtorKind::Const), _) => traits::IsConstable::Ctor,
-                    _ => traits::IsConstable::No,
-                }
-            }
-            _ => traits::IsConstable::No,
-        };
-
-        let lang_item = self.tcx.require_lang_item(LangItem::Copy, None);
-        let code =
-            traits::ObligationCauseCode::RepeatElementCopy { is_constable, elt_span: element.span };
-        self.require_type_meets(element_ty, element.span, code, lang_item);
-    }
-
     fn check_expr_tuple(
         &self,
         elts: &'tcx [hir::Expr<'tcx>],
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
index d2cdfe22a3a..786d7639a05 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs
@@ -4,12 +4,12 @@ use itertools::Itertools;
 use rustc_data_structures::fx::FxIndexSet;
 use rustc_errors::codes::*;
 use rustc_errors::{Applicability, Diag, ErrorGuaranteed, MultiSpan, a_or_an, listify, pluralize};
-use rustc_hir::def::{CtorOf, DefKind, Res};
+use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
 use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::Visitor;
-use rustc_hir::{ExprKind, HirId, Node, QPath};
+use rustc_hir::{ExprKind, HirId, LangItem, Node, QPath};
 use rustc_hir_analysis::check::potentially_plural_count;
-use rustc_hir_analysis::hir_ty_lowering::HirTyLowerer;
+use rustc_hir_analysis::hir_ty_lowering::{HirTyLowerer, PermitVariants};
 use rustc_index::IndexVec;
 use rustc_infer::infer::{DefineOpaqueTypes, InferOk, TypeTrace};
 use rustc_middle::ty::adjustment::AllowTwoPhase;
@@ -104,24 +104,96 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     pub(in super::super) fn check_repeat_exprs(&self) {
         let mut deferred_repeat_expr_checks = self.deferred_repeat_expr_checks.borrow_mut();
         debug!("FnCtxt::check_repeat_exprs: {} deferred checks", deferred_repeat_expr_checks.len());
-        for (element, element_ty, count) in deferred_repeat_expr_checks.drain(..) {
-            // We want to emit an error if the const is not structurally resolveable as otherwise
-            // we can find up conservatively proving `Copy` which may infer the repeat expr count
-            // to something that never required `Copy` in the first place.
-            let count =
-                self.structurally_resolve_const(element.span, self.normalize(element.span, count));
-
-            // Avoid run on "`NotCopy: Copy` is not implemented" errors when the repeat expr count
-            // is erroneous/unknown. The user might wind up specifying a repeat count of 0/1.
-            if count.references_error() {
-                continue;
-            }
 
-            // If the length is 0, we don't create any elements, so we don't copy any.
-            // If the length is 1, we don't copy that one element, we move it. Only check
-            // for `Copy` if the length is larger.
-            if count.try_to_target_usize(self.tcx).is_none_or(|x| x > 1) {
-                self.enforce_repeat_element_needs_copy_bound(element, element_ty);
+        let deferred_repeat_expr_checks = deferred_repeat_expr_checks
+            .drain(..)
+            .flat_map(|(element, element_ty, count)| {
+                // Actual constants as the repeat element are inserted repeatedly instead
+                // of being copied via `Copy`, so we don't need to attempt to structurally
+                // resolve the repeat count which may unnecessarily error.
+                match &element.kind {
+                    hir::ExprKind::ConstBlock(..) => return None,
+                    hir::ExprKind::Path(qpath) => {
+                        let res = self.typeck_results.borrow().qpath_res(qpath, element.hir_id);
+                        if let Res::Def(DefKind::Const | DefKind::AssocConst, _) = res {
+                            return None;
+                        }
+                    }
+                    _ => {}
+                }
+
+                // We want to emit an error if the const is not structurally resolveable
+                // as otherwise we can wind up conservatively proving `Copy` which may
+                // infer the repeat expr count to something that never required `Copy` in
+                // the first place.
+                let count = self
+                    .structurally_resolve_const(element.span, self.normalize(element.span, count));
+
+                // Avoid run on "`NotCopy: Copy` is not implemented" errors when the
+                // repeat expr count is erroneous/unknown. The user might wind up
+                // specifying a repeat count of 0/1.
+                if count.references_error() {
+                    return None;
+                }
+
+                Some((element, element_ty, count))
+            })
+            // We collect to force the side effects of structurally resolving the repeat
+            // count to happen in one go, to avoid side effects from proving `Copy`
+            // affecting whether repeat counts are known or not. If we did not do this we
+            // would get results that depend on the order that we evaluate each repeat
+            // expr's `Copy` check.
+            .collect::<Vec<_>>();
+
+        let enforce_copy_bound = |element: &hir::Expr<'_>, element_ty| {
+            // If someone calls a const fn or constructs a const value, they can extract that
+            // out into a separate constant (or a const block in the future), so we check that
+            // to tell them that in the diagnostic. Does not affect typeck.
+            let is_constable = match element.kind {
+                hir::ExprKind::Call(func, _args) => match *self.node_ty(func.hir_id).kind() {
+                    ty::FnDef(def_id, _) if self.tcx.is_stable_const_fn(def_id) => {
+                        traits::IsConstable::Fn
+                    }
+                    _ => traits::IsConstable::No,
+                },
+                hir::ExprKind::Path(qpath) => {
+                    match self.typeck_results.borrow().qpath_res(&qpath, element.hir_id) {
+                        Res::Def(DefKind::Ctor(_, CtorKind::Const), _) => traits::IsConstable::Ctor,
+                        _ => traits::IsConstable::No,
+                    }
+                }
+                _ => traits::IsConstable::No,
+            };
+
+            let lang_item = self.tcx.require_lang_item(LangItem::Copy, None);
+            let code = traits::ObligationCauseCode::RepeatElementCopy {
+                is_constable,
+                elt_span: element.span,
+            };
+            self.require_type_meets(element_ty, element.span, code, lang_item);
+        };
+
+        for (element, element_ty, count) in deferred_repeat_expr_checks {
+            match count.kind() {
+                ty::ConstKind::Value(val) => {
+                    if val.try_to_target_usize(self.tcx).is_none_or(|count| count > 1) {
+                        enforce_copy_bound(element, element_ty)
+                    } else {
+                        // If the length is 0 or 1 we don't actually copy the element, we either don't create it
+                        // or we just use the one value.
+                    }
+                }
+
+                // If the length is a generic parameter or some rigid alias then conservatively
+                // require `element_ty: Copy` as it may wind up being `>1` after monomorphization.
+                ty::ConstKind::Param(_)
+                | ty::ConstKind::Expr(_)
+                | ty::ConstKind::Placeholder(_)
+                | ty::ConstKind::Unevaluated(_) => enforce_copy_bound(element, element_ty),
+
+                ty::ConstKind::Bound(_, _) | ty::ConstKind::Infer(_) | ty::ConstKind::Error(_) => {
+                    unreachable!()
+                }
             }
         }
     }
@@ -2105,15 +2177,25 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         match *qpath {
             QPath::Resolved(ref maybe_qself, path) => {
                 let self_ty = maybe_qself.as_ref().map(|qself| self.lower_ty(qself).raw);
-                let ty = self.lowerer().lower_path(self_ty, path, hir_id, true);
+                let ty = self.lowerer().lower_resolved_ty_path(
+                    self_ty,
+                    path,
+                    hir_id,
+                    PermitVariants::Yes,
+                );
                 (path.res, LoweredTy::from_raw(self, path_span, ty))
             }
-            QPath::TypeRelative(qself, segment) => {
-                let ty = self.lower_ty(qself);
+            QPath::TypeRelative(hir_self_ty, segment) => {
+                let self_ty = self.lower_ty(hir_self_ty);
 
-                let result = self
-                    .lowerer()
-                    .lower_assoc_path_ty(hir_id, path_span, ty.raw, qself, segment, true);
+                let result = self.lowerer().lower_type_relative_ty_path(
+                    self_ty.raw,
+                    hir_self_ty,
+                    segment,
+                    hir_id,
+                    path_span,
+                    PermitVariants::Yes,
+                );
                 let ty = result
                     .map(|(ty, _, _)| ty)
                     .unwrap_or_else(|guar| Ty::new_error(self.tcx(), guar));
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
index de189b30109..ea0adf16b1a 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs
@@ -308,17 +308,16 @@ impl<'tcx> HirTyLowerer<'tcx> for FnCtxt<'_, 'tcx> {
         ))
     }
 
-    fn lower_assoc_shared(
+    fn lower_assoc_item_path(
         &self,
         span: Span,
         item_def_id: DefId,
         item_segment: &rustc_hir::PathSegment<'tcx>,
         poly_trait_ref: ty::PolyTraitRef<'tcx>,
-        _assoc_tag: ty::AssocTag,
     ) -> Result<(DefId, ty::GenericArgsRef<'tcx>), ErrorGuaranteed> {
         let trait_ref = self.instantiate_binder_with_fresh_vars(
             span,
-            // FIXME(mgca): this should be assoc const if that is the `kind`
+            // FIXME(mgca): `item_def_id` can be an AssocConst; rename this variant.
             infer::BoundRegionConversionTime::AssocTypeProjection(item_def_id),
             poly_trait_ref,
         );
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs
index 1079262b5af..43b662ca453 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs
@@ -764,6 +764,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expression: &'tcx hir::Expr<'tcx>,
         expected: Ty<'tcx>,
         needs_block: bool,
+        parent_is_closure: bool,
     ) {
         if expected.is_unit() {
             // `BlockTailExpression` only relevant if the tail expr would be
@@ -799,6 +800,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         );
                     }
                 }
+                ExprKind::Path(..) | ExprKind::Lit(_)
+                    if parent_is_closure
+                        && !expression.span.in_external_macro(self.tcx.sess.source_map()) =>
+                {
+                    err.span_suggestion_verbose(
+                        expression.span.shrink_to_lo(),
+                        "consider ignoring the value",
+                        "_ = ",
+                        Applicability::MachineApplicable,
+                    );
+                }
                 _ => (),
             }
         }
diff --git a/compiler/rustc_hir_typeck/src/lib.rs b/compiler/rustc_hir_typeck/src/lib.rs
index a7444b45ab0..5a814822163 100644
--- a/compiler/rustc_hir_typeck/src/lib.rs
+++ b/compiler/rustc_hir_typeck/src/lib.rs
@@ -196,13 +196,16 @@ fn typeck_with_inspect<'tcx>(
         fcx.write_ty(id, expected_type);
     };
 
-    // Whether to check repeat exprs before/after inference fallback is somewhat arbitrary of a decision
-    // as neither option is strictly more permissive than the other. However, we opt to check repeat exprs
-    // first as errors from not having inferred array lengths yet seem less confusing than errors from inference
-    // fallback arbitrarily inferring something incompatible with `Copy` inference side effects.
+    // Whether to check repeat exprs before/after inference fallback is somewhat
+    // arbitrary of a decision as neither option is strictly more permissive than
+    // the other. However, we opt to check repeat exprs first as errors from not
+    // having inferred array lengths yet seem less confusing than errors from inference
+    // fallback arbitrarily inferring something incompatible with `Copy` inference
+    // side effects.
     //
-    // This should also be forwards compatible with moving repeat expr checks to a custom goal kind or using
-    // marker traits in the future.
+    // FIXME(#140855): This should also be forwards compatible with moving
+    // repeat expr checks to a custom goal kind or using marker traits in
+    // the future.
     fcx.check_repeat_exprs();
 
     fcx.type_inference_fallback();
diff --git a/compiler/rustc_hir_typeck/src/method/confirm.rs b/compiler/rustc_hir_typeck/src/method/confirm.rs
index a614b4f00ff..53b5dff9c6b 100644
--- a/compiler/rustc_hir_typeck/src/method/confirm.rs
+++ b/compiler/rustc_hir_typeck/src/method/confirm.rs
@@ -291,6 +291,14 @@ impl<'a, 'tcx> ConfirmContext<'a, 'tcx> {
             probe::ObjectPick => {
                 let trait_def_id = pick.item.container_id(self.tcx);
 
+                // If the trait is not object safe (specifically, we care about when
+                // the receiver is not valid), then there's a chance that we will not
+                // actually be able to recover the object by derefing the receiver like
+                // we should if it were valid.
+                if !self.tcx.is_dyn_compatible(trait_def_id) {
+                    return ty::GenericArgs::extend_with_error(self.tcx, trait_def_id, &[]);
+                }
+
                 // This shouldn't happen for non-region error kinds, but may occur
                 // when we have error regions. Specifically, since we canonicalize
                 // during method steps, we may successfully deref when we assemble
diff --git a/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs b/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs
index a1a0926cd81..26ecaebe97f 100644
--- a/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs
+++ b/compiler/rustc_infer/src/infer/canonical/canonicalizer.rs
@@ -17,8 +17,7 @@ use tracing::debug;
 
 use crate::infer::InferCtxt;
 use crate::infer::canonical::{
-    Canonical, CanonicalQueryInput, CanonicalTyVarKind, CanonicalVarInfo, CanonicalVarKind,
-    OriginalQueryValues,
+    Canonical, CanonicalQueryInput, CanonicalTyVarKind, CanonicalVarKind, OriginalQueryValues,
 };
 
 impl<'tcx> InferCtxt<'tcx> {
@@ -174,10 +173,8 @@ impl CanonicalizeMode for CanonicalizeQueryResponse {
         match r.kind() {
             ty::ReLateParam(_) | ty::ReErased | ty::ReStatic | ty::ReEarlyParam(..) => r,
 
-            ty::RePlaceholder(placeholder) => canonicalizer.canonical_var_for_region(
-                CanonicalVarInfo { kind: CanonicalVarKind::PlaceholderRegion(placeholder) },
-                r,
-            ),
+            ty::RePlaceholder(placeholder) => canonicalizer
+                .canonical_var_for_region(CanonicalVarKind::PlaceholderRegion(placeholder), r),
 
             ty::ReVar(vid) => {
                 let universe = infcx
@@ -186,10 +183,7 @@ impl CanonicalizeMode for CanonicalizeQueryResponse {
                     .unwrap_region_constraints()
                     .probe_value(vid)
                     .unwrap_err();
-                canonicalizer.canonical_var_for_region(
-                    CanonicalVarInfo { kind: CanonicalVarKind::Region(universe) },
-                    r,
-                )
+                canonicalizer.canonical_var_for_region(CanonicalVarKind::Region(universe), r)
             }
 
             _ => {
@@ -294,7 +288,7 @@ struct Canonicalizer<'cx, 'tcx> {
     /// Set to `None` to disable the resolution of inference variables.
     infcx: Option<&'cx InferCtxt<'tcx>>,
     tcx: TyCtxt<'tcx>,
-    variables: SmallVec<[CanonicalVarInfo<'tcx>; 8]>,
+    variables: SmallVec<[CanonicalVarKind<'tcx>; 8]>,
     query_state: &'cx mut OriginalQueryValues<'tcx>,
     // Note that indices is only used once `var_values` is big enough to be
     // heap-allocated.
@@ -368,9 +362,7 @@ impl<'cx, 'tcx> TypeFolder<TyCtxt<'tcx>> for Canonicalizer<'cx, 'tcx> {
                             ui = ty::UniverseIndex::ROOT;
                         }
                         self.canonicalize_ty_var(
-                            CanonicalVarInfo {
-                                kind: CanonicalVarKind::Ty(CanonicalTyVarKind::General(ui)),
-                            },
+                            CanonicalVarKind::Ty(CanonicalTyVarKind::General(ui)),
                             t,
                         )
                     }
@@ -382,10 +374,7 @@ impl<'cx, 'tcx> TypeFolder<TyCtxt<'tcx>> for Canonicalizer<'cx, 'tcx> {
                 if nt != t {
                     return self.fold_ty(nt);
                 } else {
-                    self.canonicalize_ty_var(
-                        CanonicalVarInfo { kind: CanonicalVarKind::Ty(CanonicalTyVarKind::Int) },
-                        t,
-                    )
+                    self.canonicalize_ty_var(CanonicalVarKind::Ty(CanonicalTyVarKind::Int), t)
                 }
             }
             ty::Infer(ty::FloatVar(vid)) => {
@@ -393,10 +382,7 @@ impl<'cx, 'tcx> TypeFolder<TyCtxt<'tcx>> for Canonicalizer<'cx, 'tcx> {
                 if nt != t {
                     return self.fold_ty(nt);
                 } else {
-                    self.canonicalize_ty_var(
-                        CanonicalVarInfo { kind: CanonicalVarKind::Ty(CanonicalTyVarKind::Float) },
-                        t,
-                    )
+                    self.canonicalize_ty_var(CanonicalVarKind::Ty(CanonicalTyVarKind::Float), t)
                 }
             }
 
@@ -408,10 +394,7 @@ impl<'cx, 'tcx> TypeFolder<TyCtxt<'tcx>> for Canonicalizer<'cx, 'tcx> {
                 if !self.canonicalize_mode.preserve_universes() {
                     placeholder.universe = ty::UniverseIndex::ROOT;
                 }
-                self.canonicalize_ty_var(
-                    CanonicalVarInfo { kind: CanonicalVarKind::PlaceholderTy(placeholder) },
-                    t,
-                )
+                self.canonicalize_ty_var(CanonicalVarKind::PlaceholderTy(placeholder), t)
             }
 
             ty::Bound(debruijn, _) => {
@@ -483,10 +466,7 @@ impl<'cx, 'tcx> TypeFolder<TyCtxt<'tcx>> for Canonicalizer<'cx, 'tcx> {
                             // FIXME: perf problem described in #55921.
                             ui = ty::UniverseIndex::ROOT;
                         }
-                        return self.canonicalize_const_var(
-                            CanonicalVarInfo { kind: CanonicalVarKind::Const(ui) },
-                            ct,
-                        );
+                        return self.canonicalize_const_var(CanonicalVarKind::Const(ui), ct);
                     }
                 }
             }
@@ -501,10 +481,8 @@ impl<'cx, 'tcx> TypeFolder<TyCtxt<'tcx>> for Canonicalizer<'cx, 'tcx> {
                 }
             }
             ty::ConstKind::Placeholder(placeholder) => {
-                return self.canonicalize_const_var(
-                    CanonicalVarInfo { kind: CanonicalVarKind::PlaceholderConst(placeholder) },
-                    ct,
-                );
+                return self
+                    .canonicalize_const_var(CanonicalVarKind::PlaceholderConst(placeholder), ct);
             }
             _ => {}
         }
@@ -595,7 +573,7 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
         debug_assert!(!out_value.has_infer() && !out_value.has_placeholders());
 
         let canonical_variables =
-            tcx.mk_canonical_var_infos(&canonicalizer.universe_canonicalized_variables());
+            tcx.mk_canonical_var_kinds(&canonicalizer.universe_canonicalized_variables());
 
         let max_universe = canonical_variables
             .iter()
@@ -610,18 +588,22 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
     /// or returns an existing variable if `kind` has already been
     /// seen. `kind` is expected to be an unbound variable (or
     /// potentially a free region).
-    fn canonical_var(&mut self, info: CanonicalVarInfo<'tcx>, kind: GenericArg<'tcx>) -> BoundVar {
+    fn canonical_var(
+        &mut self,
+        var_kind: CanonicalVarKind<'tcx>,
+        value: GenericArg<'tcx>,
+    ) -> BoundVar {
         let Canonicalizer { variables, query_state, indices, .. } = self;
 
         let var_values = &mut query_state.var_values;
 
-        let universe = info.universe();
+        let universe = var_kind.universe();
         if universe != ty::UniverseIndex::ROOT {
             assert!(self.canonicalize_mode.preserve_universes());
 
             // Insert universe into the universe map. To preserve the order of the
             // universes in the value being canonicalized, we don't update the
-            // universe in `info` until we have finished canonicalizing.
+            // universe in `var_kind` until we have finished canonicalizing.
             match query_state.universe_map.binary_search(&universe) {
                 Err(idx) => query_state.universe_map.insert(idx, universe),
                 Ok(_) => {}
@@ -636,14 +618,14 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
         if !var_values.spilled() {
             // `var_values` is stack-allocated. `indices` isn't used yet. Do a
             // direct linear search of `var_values`.
-            if let Some(idx) = var_values.iter().position(|&k| k == kind) {
+            if let Some(idx) = var_values.iter().position(|&v| v == value) {
                 // `kind` is already present in `var_values`.
                 BoundVar::new(idx)
             } else {
                 // `kind` isn't present in `var_values`. Append it. Likewise
-                // for `info` and `variables`.
-                variables.push(info);
-                var_values.push(kind);
+                // for `var_kind` and `variables`.
+                variables.push(var_kind);
+                var_values.push(value);
                 assert_eq!(variables.len(), var_values.len());
 
                 // If `var_values` has become big enough to be heap-allocated,
@@ -653,7 +635,7 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
                     *indices = var_values
                         .iter()
                         .enumerate()
-                        .map(|(i, &kind)| (kind, BoundVar::new(i)))
+                        .map(|(i, &value)| (value, BoundVar::new(i)))
                         .collect();
                 }
                 // The cv is the index of the appended element.
@@ -661,9 +643,9 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
             }
         } else {
             // `var_values` is large. Do a hashmap search via `indices`.
-            *indices.entry(kind).or_insert_with(|| {
-                variables.push(info);
-                var_values.push(kind);
+            *indices.entry(value).or_insert_with(|| {
+                variables.push(var_kind);
+                var_values.push(value);
                 assert_eq!(variables.len(), var_values.len());
                 BoundVar::new(variables.len() - 1)
             })
@@ -673,7 +655,7 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
     /// Replaces the universe indexes used in `var_values` with their index in
     /// `query_state.universe_map`. This minimizes the maximum universe used in
     /// the canonicalized value.
-    fn universe_canonicalized_variables(self) -> SmallVec<[CanonicalVarInfo<'tcx>; 8]> {
+    fn universe_canonicalized_variables(self) -> SmallVec<[CanonicalVarKind<'tcx>; 8]> {
         if self.query_state.universe_map.len() == 1 {
             return self.variables;
         }
@@ -688,37 +670,33 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
 
         self.variables
             .iter()
-            .map(|v| CanonicalVarInfo {
-                kind: match v.kind {
-                    CanonicalVarKind::Ty(CanonicalTyVarKind::Int | CanonicalTyVarKind::Float) => {
-                        return *v;
-                    }
-                    CanonicalVarKind::Ty(CanonicalTyVarKind::General(u)) => {
-                        CanonicalVarKind::Ty(CanonicalTyVarKind::General(reverse_universe_map[&u]))
-                    }
-                    CanonicalVarKind::Region(u) => {
-                        CanonicalVarKind::Region(reverse_universe_map[&u])
-                    }
-                    CanonicalVarKind::Const(u) => CanonicalVarKind::Const(reverse_universe_map[&u]),
-                    CanonicalVarKind::PlaceholderTy(placeholder) => {
-                        CanonicalVarKind::PlaceholderTy(ty::Placeholder {
-                            universe: reverse_universe_map[&placeholder.universe],
-                            ..placeholder
-                        })
-                    }
-                    CanonicalVarKind::PlaceholderRegion(placeholder) => {
-                        CanonicalVarKind::PlaceholderRegion(ty::Placeholder {
-                            universe: reverse_universe_map[&placeholder.universe],
-                            ..placeholder
-                        })
-                    }
-                    CanonicalVarKind::PlaceholderConst(placeholder) => {
-                        CanonicalVarKind::PlaceholderConst(ty::Placeholder {
-                            universe: reverse_universe_map[&placeholder.universe],
-                            ..placeholder
-                        })
-                    }
-                },
+            .map(|&kind| match kind {
+                CanonicalVarKind::Ty(CanonicalTyVarKind::Int | CanonicalTyVarKind::Float) => {
+                    return kind;
+                }
+                CanonicalVarKind::Ty(CanonicalTyVarKind::General(u)) => {
+                    CanonicalVarKind::Ty(CanonicalTyVarKind::General(reverse_universe_map[&u]))
+                }
+                CanonicalVarKind::Region(u) => CanonicalVarKind::Region(reverse_universe_map[&u]),
+                CanonicalVarKind::Const(u) => CanonicalVarKind::Const(reverse_universe_map[&u]),
+                CanonicalVarKind::PlaceholderTy(placeholder) => {
+                    CanonicalVarKind::PlaceholderTy(ty::Placeholder {
+                        universe: reverse_universe_map[&placeholder.universe],
+                        ..placeholder
+                    })
+                }
+                CanonicalVarKind::PlaceholderRegion(placeholder) => {
+                    CanonicalVarKind::PlaceholderRegion(ty::Placeholder {
+                        universe: reverse_universe_map[&placeholder.universe],
+                        ..placeholder
+                    })
+                }
+                CanonicalVarKind::PlaceholderConst(placeholder) => {
+                    CanonicalVarKind::PlaceholderConst(ty::Placeholder {
+                        universe: reverse_universe_map[&placeholder.universe],
+                        ..placeholder
+                    })
+                }
             })
             .collect()
     }
@@ -740,20 +718,17 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
         &mut self,
         r: ty::Region<'tcx>,
     ) -> ty::Region<'tcx> {
-        self.canonical_var_for_region(
-            CanonicalVarInfo { kind: CanonicalVarKind::Region(ty::UniverseIndex::ROOT) },
-            r,
-        )
+        self.canonical_var_for_region(CanonicalVarKind::Region(ty::UniverseIndex::ROOT), r)
     }
 
     /// Creates a canonical variable (with the given `info`)
     /// representing the region `r`; return a region referencing it.
     fn canonical_var_for_region(
         &mut self,
-        info: CanonicalVarInfo<'tcx>,
+        var_kind: CanonicalVarKind<'tcx>,
         r: ty::Region<'tcx>,
     ) -> ty::Region<'tcx> {
-        let var = self.canonical_var(info, r.into());
+        let var = self.canonical_var(var_kind, r.into());
         let br = ty::BoundRegion { var, kind: ty::BoundRegionKind::Anon };
         ty::Region::new_bound(self.cx(), self.binder_index, br)
     }
@@ -762,9 +737,13 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
     /// if `ty_var` is bound to anything; if so, canonicalize
     /// *that*. Otherwise, create a new canonical variable for
     /// `ty_var`.
-    fn canonicalize_ty_var(&mut self, info: CanonicalVarInfo<'tcx>, ty_var: Ty<'tcx>) -> Ty<'tcx> {
+    fn canonicalize_ty_var(
+        &mut self,
+        var_kind: CanonicalVarKind<'tcx>,
+        ty_var: Ty<'tcx>,
+    ) -> Ty<'tcx> {
         debug_assert!(!self.infcx.is_some_and(|infcx| ty_var != infcx.shallow_resolve(ty_var)));
-        let var = self.canonical_var(info, ty_var.into());
+        let var = self.canonical_var(var_kind, ty_var.into());
         Ty::new_bound(self.tcx, self.binder_index, var.into())
     }
 
@@ -774,13 +753,13 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
     /// `const_var`.
     fn canonicalize_const_var(
         &mut self,
-        info: CanonicalVarInfo<'tcx>,
-        const_var: ty::Const<'tcx>,
+        var_kind: CanonicalVarKind<'tcx>,
+        ct_var: ty::Const<'tcx>,
     ) -> ty::Const<'tcx> {
         debug_assert!(
-            !self.infcx.is_some_and(|infcx| const_var != infcx.shallow_resolve_const(const_var))
+            !self.infcx.is_some_and(|infcx| ct_var != infcx.shallow_resolve_const(ct_var))
         );
-        let var = self.canonical_var(info, const_var.into());
+        let var = self.canonical_var(var_kind, ct_var.into());
         ty::Const::new_bound(self.tcx, self.binder_index, var)
     }
 }
diff --git a/compiler/rustc_infer/src/infer/canonical/mod.rs b/compiler/rustc_infer/src/infer/canonical/mod.rs
index 3be07dbe208..5dffedc7099 100644
--- a/compiler/rustc_infer/src/infer/canonical/mod.rs
+++ b/compiler/rustc_infer/src/infer/canonical/mod.rs
@@ -81,14 +81,14 @@ impl<'tcx> InferCtxt<'tcx> {
     fn instantiate_canonical_vars(
         &self,
         span: Span,
-        variables: &List<CanonicalVarInfo<'tcx>>,
+        variables: &List<CanonicalVarKind<'tcx>>,
         universe_map: impl Fn(ty::UniverseIndex) -> ty::UniverseIndex,
     ) -> CanonicalVarValues<'tcx> {
         CanonicalVarValues {
             var_values: self.tcx.mk_args_from_iter(
                 variables
                     .iter()
-                    .map(|info| self.instantiate_canonical_var(span, info, &universe_map)),
+                    .map(|kind| self.instantiate_canonical_var(span, kind, &universe_map)),
             ),
         }
     }
@@ -104,10 +104,10 @@ impl<'tcx> InferCtxt<'tcx> {
     pub fn instantiate_canonical_var(
         &self,
         span: Span,
-        cv_info: CanonicalVarInfo<'tcx>,
+        kind: CanonicalVarKind<'tcx>,
         universe_map: impl Fn(ty::UniverseIndex) -> ty::UniverseIndex,
     ) -> GenericArg<'tcx> {
-        match cv_info.kind {
+        match kind {
             CanonicalVarKind::Ty(ty_kind) => {
                 let ty = match ty_kind {
                     CanonicalTyVarKind::General(ui) => {
diff --git a/compiler/rustc_infer/src/infer/canonical/query_response.rs b/compiler/rustc_infer/src/infer/canonical/query_response.rs
index 1ae864c454f..ec72e05494b 100644
--- a/compiler/rustc_infer/src/infer/canonical/query_response.rs
+++ b/compiler/rustc_infer/src/infer/canonical/query_response.rs
@@ -445,17 +445,17 @@ impl<'tcx> InferCtxt<'tcx> {
         // a fresh inference variable.
         let result_args = CanonicalVarValues {
             var_values: self.tcx.mk_args_from_iter(
-                query_response.variables.iter().enumerate().map(|(index, info)| {
-                    if info.universe() != ty::UniverseIndex::ROOT {
+                query_response.variables.iter().enumerate().map(|(index, var_kind)| {
+                    if var_kind.universe() != ty::UniverseIndex::ROOT {
                         // A variable from inside a binder of the query. While ideally these shouldn't
                         // exist at all, we have to deal with them for now.
-                        self.instantiate_canonical_var(cause.span, info, |u| {
+                        self.instantiate_canonical_var(cause.span, var_kind, |u| {
                             universe_map[u.as_usize()]
                         })
-                    } else if info.is_existential() {
+                    } else if var_kind.is_existential() {
                         match opt_values[BoundVar::new(index)] {
                             Some(k) => k,
-                            None => self.instantiate_canonical_var(cause.span, info, |u| {
+                            None => self.instantiate_canonical_var(cause.span, var_kind, |u| {
                                 universe_map[u.as_usize()]
                             }),
                         }
diff --git a/compiler/rustc_lint/messages.ftl b/compiler/rustc_lint/messages.ftl
index 999ae6360ed..b470dea5e82 100644
--- a/compiler/rustc_lint/messages.ftl
+++ b/compiler/rustc_lint/messages.ftl
@@ -837,6 +837,7 @@ lint_unexpected_cfg_name_similar_name = there is a config with a similar name
 lint_unexpected_cfg_name_similar_name_different_values = there is a config with a similar name and different values
 lint_unexpected_cfg_name_similar_name_no_value = there is a config with a similar name and no value
 lint_unexpected_cfg_name_similar_name_value = there is a config with a similar name and value
+lint_unexpected_cfg_name_version_syntax = there is a similar config predicate: `version("..")`
 lint_unexpected_cfg_name_with_similar_value = found config with similar value
 
 lint_unexpected_cfg_value = unexpected `cfg` condition value: {$has_value ->
diff --git a/compiler/rustc_lint/src/early/diagnostics/check_cfg.rs b/compiler/rustc_lint/src/early/diagnostics/check_cfg.rs
index 946dbc34f71..e2f5dd315d5 100644
--- a/compiler/rustc_lint/src/early/diagnostics/check_cfg.rs
+++ b/compiler/rustc_lint/src/early/diagnostics/check_cfg.rs
@@ -140,6 +140,14 @@ pub(super) fn unexpected_cfg_name(
 
     let code_sugg = if is_feature_cfg && is_from_cargo {
         lints::unexpected_cfg_name::CodeSuggestion::DefineFeatures
+    // Suggest correct `version("..")` predicate syntax
+    } else if let Some((_value, value_span)) = value
+        && name == sym::version
+    {
+        lints::unexpected_cfg_name::CodeSuggestion::VersionSyntax {
+            between_name_and_value: name_span.between(value_span),
+            after_value: value_span.shrink_to_hi(),
+        }
     // Suggest the most probable if we found one
     } else if let Some(best_match) = find_best_match_for_name(&possibilities, name, None) {
         is_feature_cfg |= best_match == sym::feature;
diff --git a/compiler/rustc_lint/src/lints.rs b/compiler/rustc_lint/src/lints.rs
index 686d4e84fce..caad2694f19 100644
--- a/compiler/rustc_lint/src/lints.rs
+++ b/compiler/rustc_lint/src/lints.rs
@@ -2299,6 +2299,16 @@ pub(crate) mod unexpected_cfg_name {
     pub(crate) enum CodeSuggestion {
         #[help(lint_unexpected_cfg_define_features)]
         DefineFeatures,
+        #[multipart_suggestion(
+            lint_unexpected_cfg_name_version_syntax,
+            applicability = "machine-applicable"
+        )]
+        VersionSyntax {
+            #[suggestion_part(code = "(")]
+            between_name_and_value: Span,
+            #[suggestion_part(code = ")")]
+            after_value: Span,
+        },
         #[suggestion(
             lint_unexpected_cfg_name_similar_name_value,
             applicability = "maybe-incorrect",
diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index 3cea24634fe..b8d242bad86 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -16,6 +16,7 @@ declare_lint_pass! {
     /// that are used by other parts of the compiler.
     HardwiredLints => [
         // tidy-alphabetical-start
+        AARCH64_SOFTFLOAT_NEON,
         ABSOLUTE_PATHS_NOT_STARTING_WITH_CRATE,
         AMBIGUOUS_ASSOCIATED_ITEMS,
         AMBIGUOUS_GLOB_IMPORTS,
@@ -5043,14 +5044,14 @@ declare_lint! {
     ///
     /// ```text
     /// error: this function function definition is affected by the wasm ABI transition: it passes an argument of non-scalar type `MyType`
-    /// --> $DIR/wasm_c_abi_transition.rs:17:1
-    ///  |
-    ///  | pub extern "C" fn my_fun(_x: MyType) {}
-    ///  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-    ///  |
-    ///  = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-    ///  = note: for more information, see issue #138762 <https://github.com/rust-lang/rust/issues/138762>
-    ///  = help: the "C" ABI Rust uses on wasm32-unknown-unknown will change to align with the standard "C" ABI for this target
+    ///   --> $DIR/wasm_c_abi_transition.rs:17:1
+    ///    |
+    ///    | pub extern "C" fn my_fun(_x: MyType) {}
+    ///    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+    ///    |
+    ///    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    ///    = note: for more information, see issue #138762 <https://github.com/rust-lang/rust/issues/138762>
+    ///    = help: the "C" ABI Rust uses on wasm32-unknown-unknown will change to align with the standard "C" ABI for this target
     /// ```
     ///
     /// ### Explanation
@@ -5067,3 +5068,44 @@ declare_lint! {
         reference: "issue #138762 <https://github.com/rust-lang/rust/issues/138762>",
     };
 }
+
+declare_lint! {
+    /// The `aarch64_softfloat_neon` lint detects usage of `#[target_feature(enable = "neon")]` on
+    /// softfloat aarch64 targets. Enabling this target feature causes LLVM to alter the ABI of
+    /// function calls, making this attribute unsound to use.
+    ///
+    /// ### Example
+    ///
+    /// ```rust,ignore (needs aarch64-unknown-none-softfloat)
+    /// #[target_feature(enable = "neon")]
+    /// fn with_neon() {}
+    /// ```
+    ///
+    /// This will produce:
+    ///
+    /// ```text
+    /// error: enabling the `neon` target feature on the current target is unsound due to ABI issues
+    ///   --> $DIR/abi-incompatible-target-feature-attribute-fcw.rs:11:18
+    ///    |
+    ///    | #[target_feature(enable = "neon")]
+    ///    |                  ^^^^^^^^^^^^^^^
+    ///    |
+    ///    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+    ///    = note: for more information, see issue #134375 <https://github.com/rust-lang/rust/issues/134375>
+    /// ```
+    ///
+    /// ### Explanation
+    ///
+    /// If a function like `with_neon` above ends up containing calls to LLVM builtins, those will
+    /// not use the correct ABI. This is caused by a lack of support in LLVM for mixing code with
+    /// and without the `neon` target feature. The target feature should never have been stabilized
+    /// on this target due to this issue, but the problem was not known at the time of
+    /// stabilization.
+    pub AARCH64_SOFTFLOAT_NEON,
+    Warn,
+    "detects code that could be affected by ABI issues on aarch64 softfloat targets",
+    @future_incompatible = FutureIncompatibleInfo {
+        reason: FutureIncompatibilityReason::FutureReleaseErrorReportInDeps,
+        reference: "issue #134375 <https://github.com/rust-lang/rust/issues/134375>",
+    };
+}
diff --git a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
index 97d31565733..f40a2374bea 100644
--- a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
+++ b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
@@ -425,6 +425,7 @@ provide! { tcx, def_id, other, cdata,
     doc_link_traits_in_scope => {
         tcx.arena.alloc_from_iter(cdata.get_doc_link_traits_in_scope(def_id.index))
     }
+    anon_const_kind => { table }
 }
 
 pub(in crate::rmeta) fn provide(providers: &mut Providers) {
diff --git a/compiler/rustc_metadata/src/rmeta/encoder.rs b/compiler/rustc_metadata/src/rmeta/encoder.rs
index 7ac72ef814a..3ab989d2d3b 100644
--- a/compiler/rustc_metadata/src/rmeta/encoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/encoder.rs
@@ -1569,6 +1569,9 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
                         <- tcx.explicit_implied_const_bounds(def_id).skip_binder());
                 }
             }
+            if let DefKind::AnonConst = def_kind {
+                record!(self.tables.anon_const_kind[def_id] <- self.tcx.anon_const_kind(def_id));
+            }
             if tcx.impl_method_has_trait_impl_trait_tys(def_id)
                 && let Ok(table) = self.tcx.collect_return_position_impl_trait_in_trait_tys(def_id)
             {
diff --git a/compiler/rustc_metadata/src/rmeta/mod.rs b/compiler/rustc_metadata/src/rmeta/mod.rs
index d3d928aa88e..077835283e9 100644
--- a/compiler/rustc_metadata/src/rmeta/mod.rs
+++ b/compiler/rustc_metadata/src/rmeta/mod.rs
@@ -480,6 +480,7 @@ define_tables! {
     doc_link_traits_in_scope: Table<DefIndex, LazyArray<DefId>>,
     assumed_wf_types_for_rpitit: Table<DefIndex, LazyArray<(Ty<'static>, Span)>>,
     opaque_ty_origin: Table<DefIndex, LazyValue<hir::OpaqueTyOrigin<DefId>>>,
+    anon_const_kind: Table<DefIndex, LazyValue<ty::AnonConstKind>>,
 }
 
 #[derive(TyEncodable, TyDecodable)]
diff --git a/compiler/rustc_middle/src/infer/canonical.rs b/compiler/rustc_middle/src/infer/canonical.rs
index 5b860374496..2bbc48b633c 100644
--- a/compiler/rustc_middle/src/infer/canonical.rs
+++ b/compiler/rustc_middle/src/infer/canonical.rs
@@ -27,7 +27,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::Lock;
 use rustc_macros::{HashStable, TypeFoldable, TypeVisitable};
 pub use rustc_type_ir as ir;
-pub use rustc_type_ir::{CanonicalTyVarKind, CanonicalVarKind};
+pub use rustc_type_ir::CanonicalTyVarKind;
 use smallvec::SmallVec;
 
 use crate::mir::ConstraintCategory;
@@ -35,9 +35,9 @@ use crate::ty::{self, GenericArg, List, Ty, TyCtxt, TypeFlags, TypeVisitableExt}
 
 pub type CanonicalQueryInput<'tcx, V> = ir::CanonicalQueryInput<TyCtxt<'tcx>, V>;
 pub type Canonical<'tcx, V> = ir::Canonical<TyCtxt<'tcx>, V>;
-pub type CanonicalVarInfo<'tcx> = ir::CanonicalVarInfo<TyCtxt<'tcx>>;
+pub type CanonicalVarKind<'tcx> = ir::CanonicalVarKind<TyCtxt<'tcx>>;
 pub type CanonicalVarValues<'tcx> = ir::CanonicalVarValues<TyCtxt<'tcx>>;
-pub type CanonicalVarInfos<'tcx> = &'tcx List<CanonicalVarInfo<'tcx>>;
+pub type CanonicalVarKinds<'tcx> = &'tcx List<CanonicalVarKind<'tcx>>;
 
 /// When we canonicalize a value to form a query, we wind up replacing
 /// various parts of it with canonical variables. This struct stores
diff --git a/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs b/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
index 00da1a6aeec..f21cf5fa45e 100644
--- a/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
+++ b/compiler/rustc_middle/src/middle/codegen_fn_attrs.rs
@@ -96,49 +96,46 @@ bitflags::bitflags! {
         /// `#[cold]`: a hint to LLVM that this function, when called, is never on
         /// the hot path.
         const COLD                      = 1 << 0;
-        /// `#[rustc_allocator]`: a hint to LLVM that the pointer returned from this
-        /// function is never null and the function has no side effects other than allocating.
-        const ALLOCATOR                 = 1 << 1;
-        /// An indicator that function will never unwind. Will become obsolete
-        /// once C-unwind is fully stabilized.
-        const NEVER_UNWIND              = 1 << 3;
+        /// `#[rustc_nounwind]`: An indicator that function will never unwind.
+        const NEVER_UNWIND              = 1 << 1;
         /// `#[naked]`: an indicator to LLVM that no function prologue/epilogue
         /// should be generated.
-        const NAKED                     = 1 << 4;
+        const NAKED                     = 1 << 2;
         /// `#[no_mangle]`: an indicator that the function's name should be the same
         /// as its symbol.
-        const NO_MANGLE                 = 1 << 5;
+        const NO_MANGLE                 = 1 << 3;
         /// `#[rustc_std_internal_symbol]`: an indicator that this symbol is a
         /// "weird symbol" for the standard library in that it has slightly
         /// different linkage, visibility, and reachability rules.
-        const RUSTC_STD_INTERNAL_SYMBOL = 1 << 6;
+        const RUSTC_STD_INTERNAL_SYMBOL = 1 << 4;
         /// `#[thread_local]`: indicates a static is actually a thread local
         /// piece of memory
-        const THREAD_LOCAL              = 1 << 8;
-        /// `#[used]`: indicates that LLVM can't eliminate this function (but the
+        const THREAD_LOCAL              = 1 << 5;
+        /// `#[used(compiler)]`: indicates that LLVM can't eliminate this function (but the
         /// linker can!).
-        const USED                      = 1 << 9;
+        const USED_COMPILER             = 1 << 6;
+        /// `#[used(linker)]`:
+        /// indicates that neither LLVM nor the linker will eliminate this function.
+        const USED_LINKER               = 1 << 7;
         /// `#[track_caller]`: allow access to the caller location
-        const TRACK_CALLER              = 1 << 10;
+        const TRACK_CALLER              = 1 << 8;
         /// #[ffi_pure]: applies clang's `pure` attribute to a foreign function
         /// declaration.
-        const FFI_PURE                  = 1 << 11;
+        const FFI_PURE                  = 1 << 9;
         /// #[ffi_const]: applies clang's `const` attribute to a foreign function
         /// declaration.
-        const FFI_CONST                 = 1 << 12;
-        // (Bit 13 was used for `#[cmse_nonsecure_entry]`, but is now unused.)
-        // (Bit 14 was used for `#[coverage(off)]`, but is now unused.)
-        /// `#[used(linker)]`:
-        /// indicates that neither LLVM nor the linker will eliminate this function.
-        const USED_LINKER               = 1 << 15;
+        const FFI_CONST                 = 1 << 10;
+        /// `#[rustc_allocator]`: a hint to LLVM that the pointer returned from this
+        /// function is never null and the function has no side effects other than allocating.
+        const ALLOCATOR                 = 1 << 11;
         /// `#[rustc_deallocator]`: a hint to LLVM that the function only deallocates memory.
-        const DEALLOCATOR               = 1 << 16;
+        const DEALLOCATOR               = 1 << 12;
         /// `#[rustc_reallocator]`: a hint to LLVM that the function only reallocates memory.
-        const REALLOCATOR               = 1 << 17;
+        const REALLOCATOR               = 1 << 13;
         /// `#[rustc_allocator_zeroed]`: a hint to LLVM that the function only allocates zeroed memory.
-        const ALLOCATOR_ZEROED          = 1 << 18;
+        const ALLOCATOR_ZEROED          = 1 << 14;
         /// `#[no_builtins]`: indicates that disable implicit builtin knowledge of functions for the function.
-        const NO_BUILTINS               = 1 << 19;
+        const NO_BUILTINS               = 1 << 15;
     }
 }
 rustc_data_structures::external_bitflags_debug! { CodegenFnAttrFlags }
diff --git a/compiler/rustc_middle/src/query/erase.rs b/compiler/rustc_middle/src/query/erase.rs
index 5bd111fa2f2..6035056baaf 100644
--- a/compiler/rustc_middle/src/query/erase.rs
+++ b/compiler/rustc_middle/src/query/erase.rs
@@ -6,7 +6,7 @@ use rustc_span::ErrorGuaranteed;
 
 use crate::query::CyclePlaceholder;
 use crate::ty::adjustment::CoerceUnsizedInfo;
-use crate::ty::{self, Ty};
+use crate::ty::{self, Ty, TyCtxt};
 use crate::{mir, traits};
 
 #[derive(Copy, Clone)]
@@ -207,6 +207,11 @@ impl EraseType for ty::Binder<'_, ty::FnSig<'_>> {
     type Result = [u8; size_of::<ty::Binder<'static, ty::FnSig<'static>>>()];
 }
 
+impl EraseType for ty::Binder<'_, ty::CoroutineWitnessTypes<TyCtxt<'_>>> {
+    type Result =
+        [u8; size_of::<ty::Binder<'static, ty::CoroutineWitnessTypes<TyCtxt<'static>>>>()];
+}
+
 impl EraseType for ty::Binder<'_, &'_ ty::List<Ty<'_>>> {
     type Result = [u8; size_of::<ty::Binder<'static, &'static ty::List<Ty<'static>>>>()];
 }
@@ -311,6 +316,7 @@ trivial! {
     rustc_middle::ty::Asyncness,
     rustc_middle::ty::AsyncDestructor,
     rustc_middle::ty::BoundVariableKind,
+    rustc_middle::ty::AnonConstKind,
     rustc_middle::ty::DeducedParamAttrs,
     rustc_middle::ty::Destructor,
     rustc_middle::ty::fast_reject::SimplifiedType,
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index b2133fea08c..30245bc82d4 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -922,6 +922,12 @@ rustc_queries! {
         separate_provide_extern
     }
 
+    query coroutine_hidden_types(
+        def_id: DefId
+    ) -> ty::EarlyBinder<'tcx, ty::Binder<'tcx, ty::CoroutineWitnessTypes<TyCtxt<'tcx>>>> {
+        desc { "looking up the hidden types stored across await points in a coroutine" }
+    }
+
     /// Gets a map with the variances of every item in the local crate.
     ///
     /// <div class="warning">
@@ -2586,6 +2592,11 @@ rustc_queries! {
         desc { "estimating codegen size of `{}`", key }
         cache_on_disk_if { true }
     }
+
+    query anon_const_kind(def_id: DefId) -> ty::AnonConstKind {
+        desc { |tcx| "looking up anon const kind of `{}`", tcx.def_path_str(def_id) }
+        separate_provide_extern
+    }
 }
 
 rustc_with_all_queries! { define_callbacks! }
diff --git a/compiler/rustc_middle/src/ty/codec.rs b/compiler/rustc_middle/src/ty/codec.rs
index 5ff87959a80..e0f70737add 100644
--- a/compiler/rustc_middle/src/ty/codec.rs
+++ b/compiler/rustc_middle/src/ty/codec.rs
@@ -18,7 +18,7 @@ use rustc_span::source_map::Spanned;
 use rustc_span::{Span, SpanDecoder, SpanEncoder};
 
 use crate::arena::ArenaAllocatable;
-use crate::infer::canonical::{CanonicalVarInfo, CanonicalVarInfos};
+use crate::infer::canonical::{CanonicalVarKind, CanonicalVarKinds};
 use crate::mir::interpret::{AllocId, ConstAllocation, CtfeProvenance};
 use crate::mir::mono::MonoItem;
 use crate::mir::{self};
@@ -310,11 +310,11 @@ impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for ty::Region<'tcx> {
     }
 }
 
-impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for CanonicalVarInfos<'tcx> {
+impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for CanonicalVarKinds<'tcx> {
     fn decode(decoder: &mut D) -> Self {
         let len = decoder.read_usize();
         decoder.interner().mk_canonical_var_infos_from_iter(
-            (0..len).map::<CanonicalVarInfo<'tcx>, _>(|_| Decodable::decode(decoder)),
+            (0..len).map::<CanonicalVarKind<'tcx>, _>(|_| Decodable::decode(decoder)),
         )
     }
 }
diff --git a/compiler/rustc_middle/src/ty/consts.rs b/compiler/rustc_middle/src/ty/consts.rs
index dc5fe2d8f8b..455ac660412 100644
--- a/compiler/rustc_middle/src/ty/consts.rs
+++ b/compiler/rustc_middle/src/ty/consts.rs
@@ -2,7 +2,7 @@ use std::borrow::Cow;
 
 use rustc_data_structures::intern::Interned;
 use rustc_error_messages::MultiSpan;
-use rustc_macros::HashStable;
+use rustc_macros::{HashStable, TyDecodable, TyEncodable};
 use rustc_type_ir::walk::TypeWalker;
 use rustc_type_ir::{self as ir, TypeFlags, WithCachedTypeInfo};
 
@@ -259,3 +259,16 @@ impl<'tcx> Const<'tcx> {
         TypeWalker::new(self.into())
     }
 }
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable, HashStable)]
+pub enum AnonConstKind {
+    /// `feature(generic_const_exprs)` anon consts are allowed to use arbitrary generic parameters in scope
+    GCE,
+    /// stable `min_const_generics` anon consts are not allowed to use any generic parameters
+    MCG,
+    /// anon consts used as the length of a repeat expr are syntactically allowed to use generic parameters
+    /// but must not depend on the actual instantiation. See #76200 for more information
+    RepeatExprCount,
+    /// anon consts outside of the type system, e.g. enum discriminants
+    NonTypeSystem,
+}
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 0759fa3da42..8c915fea950 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -60,7 +60,7 @@ use tracing::{debug, instrument};
 
 use crate::arena::Arena;
 use crate::dep_graph::{DepGraph, DepKindStruct};
-use crate::infer::canonical::{CanonicalParamEnvCache, CanonicalVarInfo, CanonicalVarInfos};
+use crate::infer::canonical::{CanonicalParamEnvCache, CanonicalVarKind, CanonicalVarKinds};
 use crate::lint::lint_level;
 use crate::metadata::ModChild;
 use crate::middle::codegen_fn_attrs::{CodegenFnAttrs, TargetFeature};
@@ -107,9 +107,12 @@ impl<'tcx> Interner for TyCtxt<'tcx> {
         self.mk_predefined_opaques_in_body(data)
     }
     type LocalDefIds = &'tcx ty::List<LocalDefId>;
-    type CanonicalVars = CanonicalVarInfos<'tcx>;
-    fn mk_canonical_var_infos(self, infos: &[ty::CanonicalVarInfo<Self>]) -> Self::CanonicalVars {
-        self.mk_canonical_var_infos(infos)
+    type CanonicalVarKinds = CanonicalVarKinds<'tcx>;
+    fn mk_canonical_var_kinds(
+        self,
+        kinds: &[ty::CanonicalVarKind<Self>],
+    ) -> Self::CanonicalVarKinds {
+        self.mk_canonical_var_kinds(kinds)
     }
 
     type ExternalConstraints = ExternalConstraints<'tcx>;
@@ -340,7 +343,7 @@ impl<'tcx> Interner for TyCtxt<'tcx> {
     fn coroutine_hidden_types(
         self,
         def_id: DefId,
-    ) -> ty::EarlyBinder<'tcx, ty::Binder<'tcx, &'tcx ty::List<Ty<'tcx>>>> {
+    ) -> ty::EarlyBinder<'tcx, ty::Binder<'tcx, ty::CoroutineWitnessTypes<TyCtxt<'tcx>>>> {
         self.coroutine_hidden_types(def_id)
     }
 
@@ -833,7 +836,7 @@ pub struct CtxtInterners<'tcx> {
     const_lists: InternedSet<'tcx, List<ty::Const<'tcx>>>,
     args: InternedSet<'tcx, GenericArgs<'tcx>>,
     type_lists: InternedSet<'tcx, List<Ty<'tcx>>>,
-    canonical_var_infos: InternedSet<'tcx, List<CanonicalVarInfo<'tcx>>>,
+    canonical_var_kinds: InternedSet<'tcx, List<CanonicalVarKind<'tcx>>>,
     region: InternedSet<'tcx, RegionKind<'tcx>>,
     poly_existential_predicates: InternedSet<'tcx, List<PolyExistentialPredicate<'tcx>>>,
     predicate: InternedSet<'tcx, WithCachedTypeInfo<ty::Binder<'tcx, PredicateKind<'tcx>>>>,
@@ -872,7 +875,7 @@ impl<'tcx> CtxtInterners<'tcx> {
             type_lists: InternedSet::with_capacity(N * 4),
             region: InternedSet::with_capacity(N * 4),
             poly_existential_predicates: InternedSet::with_capacity(N / 4),
-            canonical_var_infos: InternedSet::with_capacity(N / 2),
+            canonical_var_kinds: InternedSet::with_capacity(N / 2),
             predicate: InternedSet::with_capacity(N),
             clauses: InternedSet::with_capacity(N),
             projs: InternedSet::with_capacity(N * 4),
@@ -2675,7 +2678,7 @@ slice_interners!(
     const_lists: pub mk_const_list(Const<'tcx>),
     args: pub mk_args(GenericArg<'tcx>),
     type_lists: pub mk_type_list(Ty<'tcx>),
-    canonical_var_infos: pub mk_canonical_var_infos(CanonicalVarInfo<'tcx>),
+    canonical_var_kinds: pub mk_canonical_var_kinds(CanonicalVarKind<'tcx>),
     poly_existential_predicates: intern_poly_existential_predicates(PolyExistentialPredicate<'tcx>),
     projs: pub mk_projs(ProjectionKind),
     place_elems: pub mk_place_elems(PlaceElem<'tcx>),
@@ -3055,9 +3058,9 @@ impl<'tcx> TyCtxt<'tcx> {
     pub fn mk_canonical_var_infos_from_iter<I, T>(self, iter: I) -> T::Output
     where
         I: Iterator<Item = T>,
-        T: CollectAndApply<CanonicalVarInfo<'tcx>, &'tcx List<CanonicalVarInfo<'tcx>>>,
+        T: CollectAndApply<CanonicalVarKind<'tcx>, &'tcx List<CanonicalVarKind<'tcx>>>,
     {
-        T::collect_and_apply(iter, |xs| self.mk_canonical_var_infos(xs))
+        T::collect_and_apply(iter, |xs| self.mk_canonical_var_kinds(xs))
     }
 
     pub fn mk_place_elems_from_iter<I, T>(self, iter: I) -> T::Output
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index b2a58897c31..f57329608ef 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -74,8 +74,8 @@ pub use self::closure::{
     place_to_string_for_capture,
 };
 pub use self::consts::{
-    Const, ConstInt, ConstKind, Expr, ExprKind, ScalarInt, UnevaluatedConst, ValTree, ValTreeKind,
-    Value,
+    AnonConstKind, Const, ConstInt, ConstKind, Expr, ExprKind, ScalarInt, UnevaluatedConst,
+    ValTree, ValTreeKind, Value,
 };
 pub use self::context::{
     CtxtInterners, CurrentGcx, DeducedParamAttrs, Feed, FreeRegionInfo, GlobalCtxt, Lift, TyCtxt,
diff --git a/compiler/rustc_middle/src/ty/parameterized.rs b/compiler/rustc_middle/src/ty/parameterized.rs
index ecd6132b3ef..3858778bfc8 100644
--- a/compiler/rustc_middle/src/ty/parameterized.rs
+++ b/compiler/rustc_middle/src/ty/parameterized.rs
@@ -68,6 +68,7 @@ trivially_parameterized_over_tcx! {
     ty::AsyncDestructor,
     ty::AssocItemContainer,
     ty::Asyncness,
+    ty::AnonConstKind,
     ty::DeducedParamAttrs,
     ty::Destructor,
     ty::Generics,
diff --git a/compiler/rustc_middle/src/ty/util.rs b/compiler/rustc_middle/src/ty/util.rs
index 9676aa40448..ecf83926df7 100644
--- a/compiler/rustc_middle/src/ty/util.rs
+++ b/compiler/rustc_middle/src/ty/util.rs
@@ -26,7 +26,7 @@ use crate::query::Providers;
 use crate::ty::layout::{FloatExt, IntegerExt};
 use crate::ty::{
     self, Asyncness, FallibleTypeFolder, GenericArgKind, GenericArgsRef, Ty, TyCtxt, TypeFoldable,
-    TypeFolder, TypeSuperFoldable, TypeVisitableExt, Upcast, fold_regions,
+    TypeFolder, TypeSuperFoldable, TypeVisitableExt, Upcast,
 };
 
 #[derive(Copy, Clone, Debug)]
@@ -737,40 +737,6 @@ impl<'tcx> TyCtxt<'tcx> {
         }
     }
 
-    /// Return the set of types that should be taken into account when checking
-    /// trait bounds on a coroutine's internal state. This properly replaces
-    /// `ReErased` with new existential bound lifetimes.
-    pub fn coroutine_hidden_types(
-        self,
-        def_id: DefId,
-    ) -> ty::EarlyBinder<'tcx, ty::Binder<'tcx, &'tcx ty::List<Ty<'tcx>>>> {
-        let coroutine_layout = self.mir_coroutine_witnesses(def_id);
-        let mut vars = vec![];
-        let bound_tys = self.mk_type_list_from_iter(
-            coroutine_layout
-                .as_ref()
-                .map_or_else(|| [].iter(), |l| l.field_tys.iter())
-                .filter(|decl| !decl.ignore_for_traits)
-                .map(|decl| {
-                    let ty = fold_regions(self, decl.ty, |re, debruijn| {
-                        assert_eq!(re, self.lifetimes.re_erased);
-                        let var = ty::BoundVar::from_usize(vars.len());
-                        vars.push(ty::BoundVariableKind::Region(ty::BoundRegionKind::Anon));
-                        ty::Region::new_bound(
-                            self,
-                            debruijn,
-                            ty::BoundRegion { var, kind: ty::BoundRegionKind::Anon },
-                        )
-                    });
-                    ty
-                }),
-        );
-        ty::EarlyBinder::bind(ty::Binder::bind_with_vars(
-            bound_tys,
-            self.mk_bound_variable_kinds(&vars),
-        ))
-    }
-
     /// Expands the given impl trait type, stopping if the type is recursive.
     #[instrument(skip(self), level = "debug", ret)]
     pub fn try_expand_impl_trait_type(
diff --git a/compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs b/compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs
index b7d203e3cd7..e233358f386 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs
@@ -382,6 +382,9 @@ fn extend_type_not_partial_eq<'tcx>(
         fn visit_ty(&mut self, ty: Ty<'tcx>) -> Self::Result {
             match ty.kind() {
                 ty::Dynamic(..) => return ControlFlow::Break(()),
+                // Unsafe binders never implement `PartialEq`, so avoid walking into them
+                // which would require instantiating its binder with placeholders too.
+                ty::UnsafeBinder(..) => return ControlFlow::Break(()),
                 ty::FnPtr(..) => return ControlFlow::Continue(()),
                 ty::Adt(def, _args) => {
                     let ty_def_id = def.did();
diff --git a/compiler/rustc_mir_transform/src/check_unnecessary_transmutes.rs b/compiler/rustc_mir_transform/src/check_unnecessary_transmutes.rs
index 0514de3ea13..1a3715465ad 100644
--- a/compiler/rustc_mir_transform/src/check_unnecessary_transmutes.rs
+++ b/compiler/rustc_mir_transform/src/check_unnecessary_transmutes.rs
@@ -30,6 +30,7 @@ impl<'a, 'tcx> UnnecessaryTransmuteChecker<'a, 'tcx> {
         function: &Operand<'tcx>,
         arg: String,
         span: Span,
+        is_in_const: bool,
     ) -> Option<Error> {
         let fn_sig = function.ty(self.body, self.tcx).fn_sig(self.tcx).skip_binder();
         let [input] = fn_sig.inputs() else { return None };
@@ -97,8 +98,14 @@ impl<'a, 'tcx> UnnecessaryTransmuteChecker<'a, 'tcx> {
             )),
             // uNN → fNN
             (Uint(_), Float(ty)) => err(format!("{}::from_bits({arg})", ty.name_str())),
-            // bool → { x8 }
-            (Bool, Int(..) | Uint(..)) => err(format!("({arg}) as {}", fn_sig.output())),
+            // bool → { x8 } in const context since `From::from` is not const yet
+            // FIXME: is it possible to know when the parentheses arent necessary?
+            // FIXME(const_traits): Remove this when From::from is constified?
+            (Bool, Int(..) | Uint(..)) if is_in_const => {
+                err(format!("({arg}) as {}", fn_sig.output()))
+            }
+            // " using `x8::from`
+            (Bool, Int(..) | Uint(..)) => err(format!("{}::from({arg})", fn_sig.output())),
             _ => return None,
         })
     }
@@ -114,7 +121,13 @@ impl<'tcx> Visitor<'tcx> for UnnecessaryTransmuteChecker<'_, 'tcx> {
             && self.tcx.is_intrinsic(func_def_id, sym::transmute)
             && let span = self.body.source_info(location).span
             && let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(arg)
-            && let Some(lint) = self.is_unnecessary_transmute(func, snippet, span)
+            && let def_id = self.body.source.def_id()
+            && let Some(lint) = self.is_unnecessary_transmute(
+                func,
+                snippet,
+                span,
+                self.tcx.hir_body_const_context(def_id.expect_local()).is_some(),
+            )
             && let Some(hir_id) = terminator.source_info.scope.lint_root(&self.body.source_scopes)
         {
             self.tcx.emit_node_span_lint(UNNECESSARY_TRANSMUTES, hir_id, span, lint);
diff --git a/compiler/rustc_mir_transform/src/shim/async_destructor_ctor.rs b/compiler/rustc_mir_transform/src/shim/async_destructor_ctor.rs
index 7976b65aae7..fbc8ee9b06c 100644
--- a/compiler/rustc_mir_transform/src/shim/async_destructor_ctor.rs
+++ b/compiler/rustc_mir_transform/src/shim/async_destructor_ctor.rs
@@ -6,7 +6,7 @@ use rustc_middle::mir::{
     BasicBlock, BasicBlockData, Body, Local, LocalDecl, MirSource, Operand, Place, Rvalue,
     SourceInfo, Statement, StatementKind, Terminator, TerminatorKind,
 };
-use rustc_middle::ty::{self, EarlyBinder, Ty, TyCtxt};
+use rustc_middle::ty::{self, EarlyBinder, Ty, TyCtxt, TypeVisitableExt};
 
 use super::*;
 use crate::patch::MirPatch;
@@ -121,9 +121,10 @@ pub(super) fn build_async_drop_shim<'tcx>(
         parent_args.as_coroutine().resume_ty(),
     )));
     body.phase = MirPhase::Runtime(RuntimePhase::Initial);
-    if !needs_async_drop {
+    if !needs_async_drop || drop_ty.references_error() {
         // Returning noop body for types without `need async drop`
-        // (or sync Drop in case of !`need async drop` && `need drop`)
+        // (or sync Drop in case of !`need async drop` && `need drop`).
+        // And also for error types.
         return body;
     }
 
diff --git a/compiler/rustc_next_trait_solver/src/canonicalizer.rs b/compiler/rustc_next_trait_solver/src/canonicalizer.rs
index bbb4a162027..93b8940ee37 100644
--- a/compiler/rustc_next_trait_solver/src/canonicalizer.rs
+++ b/compiler/rustc_next_trait_solver/src/canonicalizer.rs
@@ -4,8 +4,8 @@ use rustc_type_ir::data_structures::{HashMap, ensure_sufficient_stack};
 use rustc_type_ir::inherent::*;
 use rustc_type_ir::solve::{Goal, QueryInput};
 use rustc_type_ir::{
-    self as ty, Canonical, CanonicalTyVarKind, CanonicalVarInfo, CanonicalVarKind, InferCtxtLike,
-    Interner, TypeFoldable, TypeFolder, TypeSuperFoldable, TypeVisitableExt,
+    self as ty, Canonical, CanonicalTyVarKind, CanonicalVarKind, InferCtxtLike, Interner,
+    TypeFoldable, TypeFolder, TypeSuperFoldable, TypeVisitableExt,
 };
 
 use crate::delegate::SolverDelegate;
@@ -50,7 +50,7 @@ pub struct Canonicalizer<'a, D: SolverDelegate<Interner = I>, I: Interner> {
 
     // Mutable fields.
     variables: &'a mut Vec<I::GenericArg>,
-    primitive_var_infos: Vec<CanonicalVarInfo<I>>,
+    var_kinds: Vec<CanonicalVarKind<I>>,
     variable_lookup_table: HashMap<I::GenericArg, usize>,
     binder_index: ty::DebruijnIndex,
 
@@ -73,7 +73,7 @@ impl<'a, D: SolverDelegate<Interner = I>, I: Interner> Canonicalizer<'a, D, I> {
 
             variables,
             variable_lookup_table: Default::default(),
-            primitive_var_infos: Vec::new(),
+            var_kinds: Vec::new(),
             binder_index: ty::INNERMOST,
 
             cache: Default::default(),
@@ -106,7 +106,7 @@ impl<'a, D: SolverDelegate<Interner = I>, I: Interner> Canonicalizer<'a, D, I> {
 
             variables,
             variable_lookup_table: Default::default(),
-            primitive_var_infos: Vec::new(),
+            var_kinds: Vec::new(),
             binder_index: ty::INNERMOST,
 
             cache: Default::default(),
@@ -123,7 +123,7 @@ impl<'a, D: SolverDelegate<Interner = I>, I: Interner> Canonicalizer<'a, D, I> {
             // We're able to reuse the `variable_lookup_table` as whether or not
             // it already contains an entry for `'static` does not matter.
             variable_lookup_table: env_canonicalizer.variable_lookup_table,
-            primitive_var_infos: env_canonicalizer.primitive_var_infos,
+            var_kinds: env_canonicalizer.var_kinds,
             binder_index: ty::INNERMOST,
 
             // We do not reuse the cache as it may contain entries whose canonicalized
@@ -149,7 +149,7 @@ impl<'a, D: SolverDelegate<Interner = I>, I: Interner> Canonicalizer<'a, D, I> {
     fn get_or_insert_bound_var(
         &mut self,
         arg: impl Into<I::GenericArg>,
-        canonical_var_info: CanonicalVarInfo<I>,
+        kind: CanonicalVarKind<I>,
     ) -> ty::BoundVar {
         // FIXME: 16 is made up and arbitrary. We should look at some
         // perf data here.
@@ -162,14 +162,14 @@ impl<'a, D: SolverDelegate<Interner = I>, I: Interner> Canonicalizer<'a, D, I> {
             *self.variable_lookup_table.entry(arg).or_insert_with(|| {
                 let var = self.variables.len();
                 self.variables.push(arg);
-                self.primitive_var_infos.push(canonical_var_info);
+                self.var_kinds.push(kind);
                 var
             })
         } else {
             self.variables.iter().position(|&v| v == arg).unwrap_or_else(|| {
                 let var = self.variables.len();
                 self.variables.push(arg);
-                self.primitive_var_infos.push(canonical_var_info);
+                self.var_kinds.push(kind);
                 var
             })
         };
@@ -177,8 +177,8 @@ impl<'a, D: SolverDelegate<Interner = I>, I: Interner> Canonicalizer<'a, D, I> {
         ty::BoundVar::from(idx)
     }
 
-    fn finalize(self) -> (ty::UniverseIndex, I::CanonicalVars) {
-        let mut var_infos = self.primitive_var_infos;
+    fn finalize(self) -> (ty::UniverseIndex, I::CanonicalVarKinds) {
+        let mut var_kinds = self.var_kinds;
         // See the rustc-dev-guide section about how we deal with universes
         // during canonicalization in the new solver.
         match self.canonicalize_mode {
@@ -192,25 +192,25 @@ impl<'a, D: SolverDelegate<Interner = I>, I: Interner> Canonicalizer<'a, D, I> {
             // information for placeholders and inference variables created inside
             // of the query.
             CanonicalizeMode::Response { max_input_universe } => {
-                for var in var_infos.iter_mut() {
+                for var in var_kinds.iter_mut() {
                     let uv = var.universe();
                     let new_uv = ty::UniverseIndex::from(
                         uv.index().saturating_sub(max_input_universe.index()),
                     );
                     *var = var.with_updated_universe(new_uv);
                 }
-                let max_universe = var_infos
+                let max_universe = var_kinds
                     .iter()
-                    .map(|info| info.universe())
+                    .map(|kind| kind.universe())
                     .max()
                     .unwrap_or(ty::UniverseIndex::ROOT);
 
-                let var_infos = self.delegate.cx().mk_canonical_var_infos(&var_infos);
-                return (max_universe, var_infos);
+                let var_kinds = self.delegate.cx().mk_canonical_var_kinds(&var_kinds);
+                return (max_universe, var_kinds);
             }
         }
 
-        // Given a `var_infos` with existentials `En` and universals `Un` in
+        // Given a `var_kinds` with existentials `En` and universals `Un` in
         // universes `n`, this algorithm compresses them in place so that:
         //
         // - the new universe indices are as small as possible
@@ -219,12 +219,12 @@ impl<'a, D: SolverDelegate<Interner = I>, I: Interner> Canonicalizer<'a, D, I> {
         //   2. put a placeholder in the same universe as an existential which cannot name it
         //
         // Let's walk through an example:
-        // - var_infos: [E0, U1, E5, U2, E2, E6, U6], curr_compressed_uv: 0, next_orig_uv: 0
-        // - var_infos: [E0, U1, E5, U2, E2, E6, U6], curr_compressed_uv: 0, next_orig_uv: 1
-        // - var_infos: [E0, U1, E5, U2, E2, E6, U6], curr_compressed_uv: 1, next_orig_uv: 2
-        // - var_infos: [E0, U1, E5, U1, E1, E6, U6], curr_compressed_uv: 1, next_orig_uv: 5
-        // - var_infos: [E0, U1, E2, U1, E1, E6, U6], curr_compressed_uv: 2, next_orig_uv: 6
-        // - var_infos: [E0, U1, E1, U1, E1, E3, U3], curr_compressed_uv: 2, next_orig_uv: -
+        // - var_kinds: [E0, U1, E5, U2, E2, E6, U6], curr_compressed_uv: 0, next_orig_uv: 0
+        // - var_kinds: [E0, U1, E5, U2, E2, E6, U6], curr_compressed_uv: 0, next_orig_uv: 1
+        // - var_kinds: [E0, U1, E5, U2, E2, E6, U6], curr_compressed_uv: 1, next_orig_uv: 2
+        // - var_kinds: [E0, U1, E5, U1, E1, E6, U6], curr_compressed_uv: 1, next_orig_uv: 5
+        // - var_kinds: [E0, U1, E2, U1, E1, E6, U6], curr_compressed_uv: 2, next_orig_uv: 6
+        // - var_kinds: [E0, U1, E1, U1, E1, E3, U3], curr_compressed_uv: 2, next_orig_uv: -
         //
         // This algorithm runs in `O(mn)` where `n` is the number of different universes and
         // `m` the number of variables. This should be fine as both are expected to be small.
@@ -232,7 +232,7 @@ impl<'a, D: SolverDelegate<Interner = I>, I: Interner> Canonicalizer<'a, D, I> {
         let mut existential_in_new_uv = None;
         let mut next_orig_uv = Some(ty::UniverseIndex::ROOT);
         while let Some(orig_uv) = next_orig_uv.take() {
-            let mut update_uv = |var: &mut CanonicalVarInfo<I>, orig_uv, is_existential| {
+            let mut update_uv = |var: &mut CanonicalVarKind<I>, orig_uv, is_existential| {
                 let uv = var.universe();
                 match uv.cmp(&orig_uv) {
                     Ordering::Less => (), // Already updated
@@ -284,7 +284,7 @@ impl<'a, D: SolverDelegate<Interner = I>, I: Interner> Canonicalizer<'a, D, I> {
             // Whenever we compress the universe of a placeholder, no existential with
             // an already compressed universe can name that placeholder.
             for is_existential in [false, true] {
-                for var in var_infos.iter_mut() {
+                for var in var_kinds.iter_mut() {
                     // We simply put all regions from the input into the highest
                     // compressed universe, so we only deal with them at the end.
                     if !var.is_region() {
@@ -298,7 +298,7 @@ impl<'a, D: SolverDelegate<Interner = I>, I: Interner> Canonicalizer<'a, D, I> {
 
         // We put all regions into a separate universe.
         let mut first_region = true;
-        for var in var_infos.iter_mut() {
+        for var in var_kinds.iter_mut() {
             if var.is_region() {
                 if first_region {
                     first_region = false;
@@ -309,8 +309,8 @@ impl<'a, D: SolverDelegate<Interner = I>, I: Interner> Canonicalizer<'a, D, I> {
             }
         }
 
-        let var_infos = self.delegate.cx().mk_canonical_var_infos(&var_infos);
-        (curr_compressed_uv, var_infos)
+        let var_kinds = self.delegate.cx().mk_canonical_var_kinds(&var_kinds);
+        (curr_compressed_uv, var_kinds)
     }
 
     fn cached_fold_ty(&mut self, t: I::Ty) -> I::Ty {
@@ -391,7 +391,7 @@ impl<'a, D: SolverDelegate<Interner = I>, I: Interner> Canonicalizer<'a, D, I> {
             }
         };
 
-        let var = self.get_or_insert_bound_var(t, CanonicalVarInfo { kind });
+        let var = self.get_or_insert_bound_var(t, kind);
 
         Ty::new_anon_bound(self.cx(), self.binder_index, var)
     }
@@ -475,7 +475,7 @@ impl<D: SolverDelegate<Interner = I>, I: Interner> TypeFolder<I> for Canonicaliz
             }
         };
 
-        let var = self.get_or_insert_bound_var(r, CanonicalVarInfo { kind });
+        let var = self.get_or_insert_bound_var(r, kind);
 
         Region::new_anon_bound(self.cx(), self.binder_index, var)
     }
@@ -525,7 +525,7 @@ impl<D: SolverDelegate<Interner = I>, I: Interner> TypeFolder<I> for Canonicaliz
             | ty::ConstKind::Expr(_) => return c.super_fold_with(self),
         };
 
-        let var = self.get_or_insert_bound_var(c, CanonicalVarInfo { kind });
+        let var = self.get_or_insert_bound_var(c, kind);
 
         Const::new_anon_bound(self.cx(), self.binder_index, var)
     }
diff --git a/compiler/rustc_next_trait_solver/src/delegate.rs b/compiler/rustc_next_trait_solver/src/delegate.rs
index bb923612cff..32dc85b3e6a 100644
--- a/compiler/rustc_next_trait_solver/src/delegate.rs
+++ b/compiler/rustc_next_trait_solver/src/delegate.rs
@@ -61,7 +61,7 @@ pub trait SolverDelegate: Deref<Target = Self::Infcx> + Sized {
 
     fn instantiate_canonical_var_with_infer(
         &self,
-        cv_info: ty::CanonicalVarInfo<Self::Interner>,
+        kind: ty::CanonicalVarKind<Self::Interner>,
         span: <Self::Interner as Interner>::Span,
         universe_map: impl Fn(ty::UniverseIndex) -> ty::UniverseIndex,
     ) -> <Self::Interner as Interner>::GenericArg;
diff --git a/compiler/rustc_next_trait_solver/src/solve/assembly/structural_traits.rs b/compiler/rustc_next_trait_solver/src/solve/assembly/structural_traits.rs
index 2a2b462a36c..4a2a7761f7f 100644
--- a/compiler/rustc_next_trait_solver/src/solve/assembly/structural_traits.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/assembly/structural_traits.rs
@@ -83,7 +83,7 @@ where
             .cx()
             .coroutine_hidden_types(def_id)
             .instantiate(cx, args)
-            .map_bound(|tys| tys.to_vec())),
+            .map_bound(|bound| bound.types.to_vec())),
 
         ty::UnsafeBinder(bound_ty) => Ok(bound_ty.map_bound(|ty| vec![ty])),
 
@@ -249,7 +249,7 @@ where
             .cx()
             .coroutine_hidden_types(def_id)
             .instantiate(ecx.cx(), args)
-            .map_bound(|tys| tys.to_vec())),
+            .map_bound(|bound| bound.types.to_vec())),
     }
 }
 
@@ -327,7 +327,7 @@ pub(in crate::solve) fn extract_tupled_inputs_and_output_from_callable<I: Intern
                 // always be called once. It additionally implements `Fn`/`FnMut`
                 // only if it has no upvars referencing the closure-env lifetime,
                 // and if the closure kind permits it.
-                if closure_kind != ty::ClosureKind::FnOnce && args.has_self_borrows() {
+                if goal_kind != ty::ClosureKind::FnOnce && args.has_self_borrows() {
                     return Err(NoSolution);
                 }
 
diff --git a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/canonical.rs b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/canonical.rs
index c62f2e2e0e9..455a178595b 100644
--- a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/canonical.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/canonical.rs
@@ -360,15 +360,15 @@ where
         }
 
         let var_values = delegate.cx().mk_args_from_iter(
-            response.variables.iter().enumerate().map(|(index, info)| {
-                if info.universe() != ty::UniverseIndex::ROOT {
+            response.variables.iter().enumerate().map(|(index, var_kind)| {
+                if var_kind.universe() != ty::UniverseIndex::ROOT {
                     // A variable from inside a binder of the query. While ideally these shouldn't
                     // exist at all (see the FIXME at the start of this method), we have to deal with
                     // them for now.
-                    delegate.instantiate_canonical_var_with_infer(info, span, |idx| {
+                    delegate.instantiate_canonical_var_with_infer(var_kind, span, |idx| {
                         prev_universe + idx.index()
                     })
-                } else if info.is_existential() {
+                } else if var_kind.is_existential() {
                     // As an optimization we sometimes avoid creating a new inference variable here.
                     //
                     // All new inference variables we create start out in the current universe of the caller.
@@ -379,12 +379,13 @@ where
                     if let Some(v) = opt_values[ty::BoundVar::from_usize(index)] {
                         v
                     } else {
-                        delegate.instantiate_canonical_var_with_infer(info, span, |_| prev_universe)
+                        delegate
+                            .instantiate_canonical_var_with_infer(var_kind, span, |_| prev_universe)
                     }
                 } else {
                     // For placeholders which were already part of the input, we simply map this
                     // universal bound variable back the placeholder of the input.
-                    original_values[info.expect_placeholder_index()]
+                    original_values[var_kind.expect_placeholder_index()]
                 }
             }),
         );
diff --git a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs
index 9a4b95903a9..dfabb94ebfc 100644
--- a/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs
@@ -91,7 +91,7 @@ where
 
     /// The variable info for the `var_values`, only used to make an ambiguous response
     /// with no constraints.
-    variables: I::CanonicalVars,
+    variables: I::CanonicalVarKinds,
 
     /// What kind of goal we're currently computing, see the enum definition
     /// for more info.
diff --git a/compiler/rustc_next_trait_solver/src/solve/mod.rs b/compiler/rustc_next_trait_solver/src/solve/mod.rs
index 8173146e2fe..2a641807154 100644
--- a/compiler/rustc_next_trait_solver/src/solve/mod.rs
+++ b/compiler/rustc_next_trait_solver/src/solve/mod.rs
@@ -354,7 +354,7 @@ where
 fn response_no_constraints_raw<I: Interner>(
     cx: I,
     max_universe: ty::UniverseIndex,
-    variables: I::CanonicalVars,
+    variables: I::CanonicalVarKinds,
     certainty: Certainty,
 ) -> CanonicalResponse<I> {
     ty::Canonical {
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index 5c0d0cf4796..1d024694049 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -35,7 +35,7 @@ use rustc_session::lint::builtin::{
     UNKNOWN_OR_MALFORMED_DIAGNOSTIC_ATTRIBUTES, UNUSED_ATTRIBUTES,
 };
 use rustc_session::parse::feature_err;
-use rustc_span::{BytePos, DUMMY_SP, Span, Symbol, edition, kw, sym};
+use rustc_span::{BytePos, DUMMY_SP, Span, Symbol, edition, sym};
 use rustc_trait_selection::error_reporting::InferCtxtErrorExt;
 use rustc_trait_selection::infer::{TyCtxtInferExt, ValuePairs};
 use rustc_trait_selection::traits::ObligationCtxt;
@@ -936,7 +936,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         let span = meta.name_value_literal_span().unwrap_or_else(|| meta.span());
         let attr_str =
             &format!("`#[doc(alias{})]`", if is_list { "(\"...\")" } else { " = \"...\"" });
-        if doc_alias == kw::Empty {
+        if doc_alias == sym::empty {
             tcx.dcx().emit_err(errors::DocAliasEmpty { span, attr_str });
             return;
         }
@@ -1068,7 +1068,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
         }
 
         let doc_keyword = match meta.value_str() {
-            Some(value) if value != kw::Empty => value,
+            Some(value) if value != sym::empty => value,
             _ => return self.doc_attr_str_error(meta, "keyword"),
         };
 
diff --git a/compiler/rustc_passes/src/dead.rs b/compiler/rustc_passes/src/dead.rs
index 0060e726a8e..6e5357d8007 100644
--- a/compiler/rustc_passes/src/dead.rs
+++ b/compiler/rustc_passes/src/dead.rs
@@ -707,7 +707,7 @@ fn has_allow_dead_code_or_lang_attr(
             // #[used], #[no_mangle], #[export_name], etc also keeps the item alive
             // forcefully, e.g., for placing it in a specific section.
             cg_attrs.contains_extern_indicator()
-                || cg_attrs.flags.contains(CodegenFnAttrFlags::USED)
+                || cg_attrs.flags.contains(CodegenFnAttrFlags::USED_COMPILER)
                 || cg_attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER)
         }
     }
diff --git a/compiler/rustc_passes/src/reachable.rs b/compiler/rustc_passes/src/reachable.rs
index f0e8fa986fe..7e15267a953 100644
--- a/compiler/rustc_passes/src/reachable.rs
+++ b/compiler/rustc_passes/src/reachable.rs
@@ -427,7 +427,7 @@ fn has_custom_linkage(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
         // FIXME(nbdd0121): `#[used]` are marked as reachable here so it's picked up by
         // `linked_symbols` in cg_ssa. They won't be exported in binary or cdylib due to their
         // `SymbolExportLevel::Rust` export level but may end up being exported in dylibs.
-        || codegen_attrs.flags.contains(CodegenFnAttrFlags::USED)
+        || codegen_attrs.flags.contains(CodegenFnAttrFlags::USED_COMPILER)
         || codegen_attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER)
 }
 
diff --git a/compiler/rustc_resolve/src/rustdoc.rs b/compiler/rustc_resolve/src/rustdoc.rs
index a32fe699016..01bb1324645 100644
--- a/compiler/rustc_resolve/src/rustdoc.rs
+++ b/compiler/rustc_resolve/src/rustdoc.rs
@@ -12,7 +12,7 @@ use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::unord::UnordSet;
 use rustc_middle::ty::TyCtxt;
 use rustc_span::def_id::DefId;
-use rustc_span::{DUMMY_SP, InnerSpan, Span, Symbol, kw, sym};
+use rustc_span::{DUMMY_SP, InnerSpan, Span, Symbol, sym};
 use thin_vec::ThinVec;
 use tracing::{debug, trace};
 
@@ -157,7 +157,7 @@ pub fn unindent_doc_fragments(docs: &mut [DocFragment]) {
     };
 
     for fragment in docs {
-        if fragment.doc == kw::Empty {
+        if fragment.doc == sym::empty {
             continue;
         }
 
@@ -177,7 +177,7 @@ pub fn unindent_doc_fragments(docs: &mut [DocFragment]) {
 ///
 /// Note: remove the trailing newline where appropriate
 pub fn add_doc_fragment(out: &mut String, frag: &DocFragment) {
-    if frag.doc == kw::Empty {
+    if frag.doc == sym::empty {
         out.push('\n');
         return;
     }
@@ -514,20 +514,30 @@ pub fn span_of_fragments(fragments: &[DocFragment]) -> Option<Span> {
 /// This method does not always work, because markdown bytes don't necessarily match source bytes,
 /// like if escapes are used in the string. In this case, it returns `None`.
 ///
-/// This method will return `Some` only if:
+/// `markdown` is typically the entire documentation for an item,
+/// after combining fragments.
+///
+/// This method will return `Some` only if one of the following is true:
 ///
 /// - The doc is made entirely from sugared doc comments, which cannot contain escapes
-/// - The doc is entirely from a single doc fragment, with a string literal, exactly equal
+/// - The doc is entirely from a single doc fragment with a string literal exactly equal to `markdown`.
 /// - The doc comes from `include_str!`
+/// - The doc includes exactly one substring matching `markdown[md_range]` which is contained in a single doc fragment.
+///
+/// This function is defined in the compiler so it can be used by
+/// both `rustdoc` and `clippy`.
 pub fn source_span_for_markdown_range(
     tcx: TyCtxt<'_>,
     markdown: &str,
     md_range: &Range<usize>,
     fragments: &[DocFragment],
 ) -> Option<Span> {
+    use rustc_span::BytePos;
+
+    let map = tcx.sess.source_map();
     if let &[fragment] = &fragments
         && fragment.kind == DocFragmentKind::RawDoc
-        && let Ok(snippet) = tcx.sess.source_map().span_to_snippet(fragment.span)
+        && let Ok(snippet) = map.span_to_snippet(fragment.span)
         && snippet.trim_end() == markdown.trim_end()
         && let Ok(md_range_lo) = u32::try_from(md_range.start)
         && let Ok(md_range_hi) = u32::try_from(md_range.end)
@@ -544,10 +554,43 @@ pub fn source_span_for_markdown_range(
     let is_all_sugared_doc = fragments.iter().all(|frag| frag.kind == DocFragmentKind::SugaredDoc);
 
     if !is_all_sugared_doc {
+        // This case ignores the markdown outside of the range so that it can
+        // work in cases where the markdown is made from several different
+        // doc fragments, but the target range does not span across multiple
+        // fragments.
+        let mut match_data = None;
+        let pat = &markdown[md_range.clone()];
+        // This heirustic doesn't make sense with a zero-sized range.
+        if pat.is_empty() {
+            return None;
+        }
+        for (i, fragment) in fragments.iter().enumerate() {
+            if let Ok(snippet) = map.span_to_snippet(fragment.span)
+                && let Some(match_start) = snippet.find(pat)
+            {
+                // If there is either a match in a previous fragment, or
+                // multiple matches in this fragment, there is ambiguity.
+                if match_data.is_none() && !snippet[match_start + 1..].contains(pat) {
+                    match_data = Some((i, match_start));
+                } else {
+                    // Heirustic produced ambiguity, return nothing.
+                    return None;
+                }
+            }
+        }
+        if let Some((i, match_start)) = match_data {
+            let sp = fragments[i].span;
+            // we need to calculate the span start,
+            // then use that in our calulations for the span end
+            let lo = sp.lo() + BytePos(match_start as u32);
+            return Some(
+                sp.with_lo(lo).with_hi(lo + BytePos((md_range.end - md_range.start) as u32)),
+            );
+        }
         return None;
     }
 
-    let snippet = tcx.sess.source_map().span_to_snippet(span_of_fragments(fragments)?).ok()?;
+    let snippet = map.span_to_snippet(span_of_fragments(fragments)?).ok()?;
 
     let starting_line = markdown[..md_range.start].matches('\n').count();
     let ending_line = starting_line + markdown[md_range.start..md_range.end].matches('\n').count();
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index fbe3b4ca6f5..6b10d2728b2 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -34,17 +34,8 @@ symbols! {
         // unnamed method parameters, crate root module, error recovery etc.
         // Matching predicates: `is_special`/`is_reserved`
         //
-        // Notes about `kw::Empty`:
-        // - Its use can blur the lines between "empty symbol" and "no symbol".
-        //   Using `Option<Symbol>` is preferable, where possible, because that
-        //   is unambiguous.
-        // - For dummy symbols that are never used and absolutely must be
-        //   present, it's better to use `sym::dummy` than `kw::Empty`, because
-        //   it's clearer that it's intended as a dummy value, and more likely
-        //   to be detected if it accidentally does get used.
         // tidy-alphabetical-start
         DollarCrate:        "$crate",
-        Empty:              "",
         PathRoot:           "{{root}}",
         Underscore:         "_",
         // tidy-alphabetical-end
@@ -398,7 +389,6 @@ symbols! {
         Wrapping,
         Yield,
         _DECLS,
-        _Self,
         __D,
         __H,
         __S,
@@ -864,7 +854,7 @@ symbols! {
         drop_types_in_const,
         dropck_eyepatch,
         dropck_parametricity,
-        dummy: "<!dummy!>", // use this instead of `kw::Empty` for symbols that won't be used
+        dummy: "<!dummy!>", // use this instead of `sym::empty` for symbols that won't be used
         dummy_cgu_name,
         dylib,
         dyn_compatible_for_dispatch,
@@ -883,6 +873,14 @@ symbols! {
         emit_enum_variant_arg,
         emit_struct,
         emit_struct_field,
+        // Notes about `sym::empty`:
+        // - It should only be used when it genuinely means "empty symbol". Use
+        //   `Option<Symbol>` when "no symbol" is a possibility.
+        // - For dummy symbols that are never used and absolutely must be
+        //   present, it's better to use `sym::dummy` than `sym::empty`, because
+        //   it's clearer that it's intended as a dummy value, and more likely
+        //   to be detected if it accidentally does get used.
+        empty: "",
         emscripten_wasm_eh,
         enable,
         encode,
@@ -2362,7 +2360,7 @@ impl Ident {
     #[inline]
     /// Constructs a new identifier from a symbol and a span.
     pub fn new(name: Symbol, span: Span) -> Ident {
-        debug_assert_ne!(name, kw::Empty);
+        debug_assert_ne!(name, sym::empty);
         Ident { name, span }
     }
 
@@ -2584,7 +2582,7 @@ impl Symbol {
     }
 
     pub fn is_empty(self) -> bool {
-        self == kw::Empty
+        self == sym::empty
     }
 
     /// This method is supposed to be used in error messages, so it's expected to be
@@ -2593,7 +2591,7 @@ impl Symbol {
     /// or edition, so we have to guess the rawness using the global edition.
     pub fn to_ident_string(self) -> String {
         // Avoid creating an empty identifier, because that asserts in debug builds.
-        if self == kw::Empty { String::new() } else { Ident::with_dummy_span(self).to_string() }
+        if self == sym::empty { String::new() } else { Ident::with_dummy_span(self).to_string() }
     }
 }
 
@@ -2773,7 +2771,7 @@ impl Symbol {
 
     /// Returns `true` if this symbol can be a raw identifier.
     pub fn can_be_raw(self) -> bool {
-        self != kw::Empty && self != kw::Underscore && !self.is_path_segment_keyword()
+        self != sym::empty && self != kw::Underscore && !self.is_path_segment_keyword()
     }
 
     /// Was this symbol predefined in the compiler's `symbols!` macro
@@ -2823,7 +2821,7 @@ impl Ident {
     /// Whether this would be the identifier for a tuple field like `self.0`, as
     /// opposed to a named field like `self.thing`.
     pub fn is_numeric(self) -> bool {
-        !self.name.is_empty() && self.as_str().bytes().all(|b| b.is_ascii_digit())
+        self.as_str().bytes().all(|b| b.is_ascii_digit())
     }
 }
 
diff --git a/compiler/rustc_symbol_mangling/src/v0.rs b/compiler/rustc_symbol_mangling/src/v0.rs
index 4a99ce09b39..644031af859 100644
--- a/compiler/rustc_symbol_mangling/src/v0.rs
+++ b/compiler/rustc_symbol_mangling/src/v0.rs
@@ -20,7 +20,7 @@ use rustc_middle::ty::{
     self, FloatTy, GenericArg, GenericArgKind, Instance, IntTy, ReifyReason, Ty, TyCtxt,
     TypeVisitable, TypeVisitableExt, UintTy,
 };
-use rustc_span::kw;
+use rustc_span::sym;
 
 pub(super) fn mangle<'tcx>(
     tcx: TyCtxt<'tcx>,
@@ -902,7 +902,7 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
             print_prefix,
             ns,
             disambiguated_data.disambiguator as u64,
-            name.unwrap_or(kw::Empty).as_str(),
+            name.unwrap_or(sym::empty).as_str(),
         )
     }
 
diff --git a/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_linux_gnu.rs
index 87c07cd3109..4b75a6e5dbf 100644
--- a/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_linux_gnu.rs
@@ -1,6 +1,6 @@
 use rustc_abi::Endian;
 
-use crate::spec::{StackProbeType, Target, TargetMetadata, TargetOptions, base};
+use crate::spec::{FramePointer, StackProbeType, Target, TargetMetadata, TargetOptions, base};
 
 pub(crate) fn target() -> Target {
     Target {
@@ -16,6 +16,10 @@ pub(crate) fn target() -> Target {
         arch: "aarch64".into(),
         options: TargetOptions {
             features: "+v8a,+outline-atomics".into(),
+            // the AAPCS64 expects use of non-leaf frame pointers per
+            // https://github.com/ARM-software/abi-aa/blob/4492d1570eb70c8fd146623e0db65b2d241f12e7/aapcs64/aapcs64.rst#the-frame-pointer
+            // and we tend to encounter interesting bugs in AArch64 unwinding code if we do not
+            frame_pointer: FramePointer::NonLeaf,
             max_atomic_width: Some(128),
             stack_probes: StackProbeType::Inline,
             mcount: "\u{1}_mcount".into(),
diff --git a/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_linux_gnu_ilp32.rs b/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_linux_gnu_ilp32.rs
index e785069c78a..2a16d1de3b5 100644
--- a/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_linux_gnu_ilp32.rs
+++ b/compiler/rustc_target/src/spec/targets/aarch64_be_unknown_linux_gnu_ilp32.rs
@@ -1,6 +1,6 @@
 use rustc_abi::Endian;
 
-use crate::spec::{StackProbeType, Target, TargetMetadata, TargetOptions, base};
+use crate::spec::{FramePointer, StackProbeType, Target, TargetMetadata, TargetOptions, base};
 
 pub(crate) fn target() -> Target {
     let mut base = base::linux_gnu::opts();
@@ -20,6 +20,10 @@ pub(crate) fn target() -> Target {
         options: TargetOptions {
             abi: "ilp32".into(),
             features: "+v8a,+outline-atomics".into(),
+            // the AAPCS64 expects use of non-leaf frame pointers per
+            // https://github.com/ARM-software/abi-aa/blob/4492d1570eb70c8fd146623e0db65b2d241f12e7/aapcs64/aapcs64.rst#the-frame-pointer
+            // and we tend to encounter interesting bugs in AArch64 unwinding code if we do not
+            frame_pointer: FramePointer::NonLeaf,
             stack_probes: StackProbeType::Inline,
             mcount: "\u{1}_mcount".into(),
             endian: Endian::Big,
diff --git a/compiler/rustc_target/src/spec/targets/aarch64_linux_android.rs b/compiler/rustc_target/src/spec/targets/aarch64_linux_android.rs
index 41c25393e12..d8651f305fe 100644
--- a/compiler/rustc_target/src/spec/targets/aarch64_linux_android.rs
+++ b/compiler/rustc_target/src/spec/targets/aarch64_linux_android.rs
@@ -1,4 +1,6 @@
-use crate::spec::{SanitizerSet, StackProbeType, Target, TargetMetadata, TargetOptions, base};
+use crate::spec::{
+    FramePointer, SanitizerSet, StackProbeType, Target, TargetMetadata, TargetOptions, base,
+};
 
 // See https://developer.android.com/ndk/guides/abis.html#arm64-v8a
 // for target ABI requirements.
@@ -20,6 +22,10 @@ pub(crate) fn target() -> Target {
             // As documented in https://developer.android.com/ndk/guides/cpu-features.html
             // the neon (ASIMD) and FP must exist on all android aarch64 targets.
             features: "+v8a,+neon,+fp-armv8".into(),
+            // the AAPCS64 expects use of non-leaf frame pointers per
+            // https://github.com/ARM-software/abi-aa/blob/4492d1570eb70c8fd146623e0db65b2d241f12e7/aapcs64/aapcs64.rst#the-frame-pointer
+            // and we tend to encounter interesting bugs in AArch64 unwinding code if we do not
+            frame_pointer: FramePointer::NonLeaf,
             stack_probes: StackProbeType::Inline,
             supported_sanitizers: SanitizerSet::CFI
                 | SanitizerSet::HWADDRESS
diff --git a/compiler/rustc_target/src/spec/targets/aarch64_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/targets/aarch64_unknown_linux_gnu.rs
index c6be2c20ea2..4220d74dfc8 100644
--- a/compiler/rustc_target/src/spec/targets/aarch64_unknown_linux_gnu.rs
+++ b/compiler/rustc_target/src/spec/targets/aarch64_unknown_linux_gnu.rs
@@ -1,4 +1,6 @@
-use crate::spec::{SanitizerSet, StackProbeType, Target, TargetMetadata, TargetOptions, base};
+use crate::spec::{
+    FramePointer, SanitizerSet, StackProbeType, Target, TargetMetadata, TargetOptions, base,
+};
 
 pub(crate) fn target() -> Target {
     Target {
@@ -14,6 +16,10 @@ pub(crate) fn target() -> Target {
         arch: "aarch64".into(),
         options: TargetOptions {
             features: "+v8a,+outline-atomics".into(),
+            // the AAPCS64 expects use of non-leaf frame pointers per
+            // https://github.com/ARM-software/abi-aa/blob/4492d1570eb70c8fd146623e0db65b2d241f12e7/aapcs64/aapcs64.rst#the-frame-pointer
+            // and we tend to encounter interesting bugs in AArch64 unwinding code if we do not
+            frame_pointer: FramePointer::NonLeaf,
             mcount: "\u{1}_mcount".into(),
             max_atomic_width: Some(128),
             stack_probes: StackProbeType::Inline,
diff --git a/compiler/rustc_target/src/spec/targets/aarch64_unknown_linux_gnu_ilp32.rs b/compiler/rustc_target/src/spec/targets/aarch64_unknown_linux_gnu_ilp32.rs
index 166bb1ed215..a22c1289677 100644
--- a/compiler/rustc_target/src/spec/targets/aarch64_unknown_linux_gnu_ilp32.rs
+++ b/compiler/rustc_target/src/spec/targets/aarch64_unknown_linux_gnu_ilp32.rs
@@ -1,4 +1,4 @@
-use crate::spec::{StackProbeType, Target, TargetMetadata, TargetOptions, base};
+use crate::spec::{FramePointer, StackProbeType, Target, TargetMetadata, TargetOptions, base};
 
 pub(crate) fn target() -> Target {
     Target {
@@ -15,6 +15,10 @@ pub(crate) fn target() -> Target {
         options: TargetOptions {
             abi: "ilp32".into(),
             features: "+v8a,+outline-atomics".into(),
+            // the AAPCS64 expects use of non-leaf frame pointers per
+            // https://github.com/ARM-software/abi-aa/blob/4492d1570eb70c8fd146623e0db65b2d241f12e7/aapcs64/aapcs64.rst#the-frame-pointer
+            // and we tend to encounter interesting bugs in AArch64 unwinding code if we do not
+            frame_pointer: FramePointer::NonLeaf,
             max_atomic_width: Some(128),
             stack_probes: StackProbeType::Inline,
             mcount: "\u{1}_mcount".into(),
diff --git a/compiler/rustc_target/src/spec/targets/aarch64_unknown_linux_musl.rs b/compiler/rustc_target/src/spec/targets/aarch64_unknown_linux_musl.rs
index 58ba06e124c..58daaa03675 100644
--- a/compiler/rustc_target/src/spec/targets/aarch64_unknown_linux_musl.rs
+++ b/compiler/rustc_target/src/spec/targets/aarch64_unknown_linux_musl.rs
@@ -1,4 +1,6 @@
-use crate::spec::{SanitizerSet, StackProbeType, Target, TargetMetadata, TargetOptions, base};
+use crate::spec::{
+    FramePointer, SanitizerSet, StackProbeType, Target, TargetMetadata, TargetOptions, base,
+};
 
 pub(crate) fn target() -> Target {
     let mut base = base::linux_musl::opts();
@@ -26,6 +28,12 @@ pub(crate) fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32".into(),
         arch: "aarch64".into(),
-        options: TargetOptions { mcount: "\u{1}_mcount".into(), ..base },
+        options: TargetOptions {
+            // the AAPCS64 expects use of non-leaf frame pointers per
+            // https://github.com/ARM-software/abi-aa/blob/4492d1570eb70c8fd146623e0db65b2d241f12e7/aapcs64/aapcs64.rst#the-frame-pointer
+            // and we tend to encounter interesting bugs in AArch64 unwinding code if we do not
+            frame_pointer: FramePointer::NonLeaf,
+             mcount: "\u{1}_mcount".into(), ..base
+         },
     }
 }
diff --git a/compiler/rustc_target/src/spec/targets/aarch64_unknown_linux_ohos.rs b/compiler/rustc_target/src/spec/targets/aarch64_unknown_linux_ohos.rs
index f2994b1232e..51cdebf22db 100644
--- a/compiler/rustc_target/src/spec/targets/aarch64_unknown_linux_ohos.rs
+++ b/compiler/rustc_target/src/spec/targets/aarch64_unknown_linux_ohos.rs
@@ -1,4 +1,6 @@
-use crate::spec::{SanitizerSet, StackProbeType, Target, TargetMetadata, TargetOptions, base};
+use crate::spec::{
+    FramePointer, SanitizerSet, StackProbeType, Target, TargetMetadata, TargetOptions, base,
+};
 
 pub(crate) fn target() -> Target {
     let mut base = base::linux_ohos::opts();
@@ -16,6 +18,10 @@ pub(crate) fn target() -> Target {
         data_layout: "e-m:e-p270:32:32-p271:32:32-p272:64:64-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-Fn32".into(),
         arch: "aarch64".into(),
         options: TargetOptions {
+            // the AAPCS64 expects use of non-leaf frame pointers per
+            // https://github.com/ARM-software/abi-aa/blob/4492d1570eb70c8fd146623e0db65b2d241f12e7/aapcs64/aapcs64.rst#the-frame-pointer
+            // and we tend to encounter interesting bugs in AArch64 unwinding code if we do not
+            frame_pointer: FramePointer::NonLeaf,
             mcount: "\u{1}_mcount".into(),
             stack_probes: StackProbeType::Inline,
             supported_sanitizers: SanitizerSet::ADDRESS
diff --git a/compiler/rustc_target/src/target_features.rs b/compiler/rustc_target/src/target_features.rs
index 99b04ac2720..576c9bd6b57 100644
--- a/compiler/rustc_target/src/target_features.rs
+++ b/compiler/rustc_target/src/target_features.rs
@@ -980,14 +980,16 @@ impl Target {
                 // the use of soft-float, so all we can do here is some crude hacks.
                 match &*self.abi {
                     "softfloat" => {
-                        // This is not fully correct, LLVM actually doesn't let us enforce the softfloat
-                        // ABI properly... see <https://github.com/rust-lang/rust/issues/134375>.
-                        // FIXME: should we forbid "neon" here? But that would be a breaking change.
-                        NOTHING
+                        // LLVM will use float registers when `fp-armv8` is available, e.g. for
+                        // calls to built-ins. The only way to ensure a consistent softfloat ABI
+                        // on aarch64 is to never enable `fp-armv8`, so we enforce that.
+                        // In Rust we tie `neon` and `fp-armv8` together, therefore `neon` is the
+                        // feature we have to mark as incompatible.
+                        FeatureConstraints { required: &[], incompatible: &["neon"] }
                     }
                     _ => {
                         // Everything else is assumed to use a hardfloat ABI. neon and fp-armv8 must be enabled.
-                        // These are Rust feature names and we use "neon" to control both of them.
+                        // `FeatureConstraints` uses Rust feature names, hence only "neon" shows up.
                         FeatureConstraints { required: &["neon"], incompatible: &[] }
                     }
                 }
diff --git a/compiler/rustc_trait_selection/messages.ftl b/compiler/rustc_trait_selection/messages.ftl
index 00922c6038e..9b949a0a795 100644
--- a/compiler/rustc_trait_selection/messages.ftl
+++ b/compiler/rustc_trait_selection/messages.ftl
@@ -337,6 +337,8 @@ trait_selection_rustc_on_unimplemented_expected_one_predicate_in_not = expected
     .label = unexpected quantity of predicates here
 trait_selection_rustc_on_unimplemented_invalid_flag = invalid flag in `on`-clause
     .label = expected one of the `crate_local`, `direct` or `from_desugaring` flags, not `{$invalid_flag}`
+trait_selection_rustc_on_unimplemented_invalid_name = invalid name in `on`-clause
+    .label = expected one of `cause`, `from_desugaring`, `Self` or any generic parameter of the trait, not `{$invalid_name}`
 trait_selection_rustc_on_unimplemented_invalid_predicate = this predicate is invalid
     .label = expected one of `any`, `all` or `not` here, not `{$invalid_pred}`
 trait_selection_rustc_on_unimplemented_missing_value = this attribute must have a value
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
index 970160ba212..b88040a0f98 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
@@ -841,16 +841,17 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                 return None;
             };
 
-        let (closure_def_id, found_args, by_ref_captures) = match *self_ty.kind() {
+        let (closure_def_id, found_args, has_self_borrows) = match *self_ty.kind() {
             ty::Closure(def_id, args) => {
-                (def_id, args.as_closure().sig().map_bound(|sig| sig.inputs()[0]), None)
+                (def_id, args.as_closure().sig().map_bound(|sig| sig.inputs()[0]), false)
             }
             ty::CoroutineClosure(def_id, args) => (
                 def_id,
                 args.as_coroutine_closure()
                     .coroutine_closure_sig()
                     .map_bound(|sig| sig.tupled_inputs_ty),
-                Some(args.as_coroutine_closure().coroutine_captures_by_ref_ty()),
+                !args.as_coroutine_closure().tupled_upvars_ty().is_ty_var()
+                    && args.as_coroutine_closure().has_self_borrows(),
             ),
             _ => return None,
         };
@@ -884,10 +885,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         // If the closure has captures, then perhaps the reason that the trait
         // is unimplemented is because async closures don't implement `Fn`/`FnMut`
         // if they have captures.
-        if let Some(by_ref_captures) = by_ref_captures
-            && let ty::FnPtr(sig_tys, _) = by_ref_captures.kind()
-            && !sig_tys.skip_binder().output().is_unit()
-        {
+        if has_self_borrows && expected_kind != ty::ClosureKind::FnOnce {
             let mut err = self.dcx().create_err(AsyncClosureNotFn {
                 span: self.tcx.def_span(closure_def_id),
                 kind: expected_kind.as_str(),
@@ -1503,11 +1501,11 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                     return None;
                 };
 
-                let Ok(Some(ImplSource::UserDefined(impl_data))) = SelectionContext::new(self)
-                    .poly_select(&obligation.with(
-                        self.tcx,
-                        predicate.kind().rebind(proj.projection_term.trait_ref(self.tcx)),
-                    ))
+                let trait_ref = self.enter_forall_and_leak_universe(
+                    predicate.kind().rebind(proj.projection_term.trait_ref(self.tcx)),
+                );
+                let Ok(Some(ImplSource::UserDefined(impl_data))) =
+                    SelectionContext::new(self).select(&obligation.with(self.tcx, trait_ref))
                 else {
                     return None;
                 };
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented.rs
index d5ee6e2123a..37968386e9a 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented.rs
@@ -429,7 +429,19 @@ impl<'tcx> OnUnimplementedDirective {
                 .next()
                 .ok_or_else(|| tcx.dcx().emit_err(InvalidOnClause::Empty { span }))?;
 
-            match OnUnimplementedCondition::parse(cond) {
+            let generics: Vec<Symbol> = tcx
+                .generics_of(item_def_id)
+                .own_params
+                .iter()
+                .filter_map(|param| {
+                    if matches!(param.kind, GenericParamDefKind::Lifetime) {
+                        None
+                    } else {
+                        Some(param.name)
+                    }
+                })
+                .collect();
+            match OnUnimplementedCondition::parse(cond, &generics) {
                 Ok(condition) => Some(condition),
                 Err(e) => return Err(tcx.dcx().emit_err(e)),
             }
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented_condition.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented_condition.rs
index 13753761f09..e8ea9f2d23e 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented_condition.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented_condition.rs
@@ -26,9 +26,12 @@ impl OnUnimplementedCondition {
         })
     }
 
-    pub(crate) fn parse(input: &MetaItemInner) -> Result<Self, InvalidOnClause> {
+    pub(crate) fn parse(
+        input: &MetaItemInner,
+        generics: &[Symbol],
+    ) -> Result<Self, InvalidOnClause> {
         let span = input.span();
-        let pred = Predicate::parse(input)?;
+        let pred = Predicate::parse(input, generics)?;
         Ok(OnUnimplementedCondition { span, pred })
     }
 }
@@ -52,7 +55,7 @@ enum Predicate {
 }
 
 impl Predicate {
-    fn parse(input: &MetaItemInner) -> Result<Self, InvalidOnClause> {
+    fn parse(input: &MetaItemInner, generics: &[Symbol]) -> Result<Self, InvalidOnClause> {
         let meta_item = match input {
             MetaItemInner::MetaItem(meta_item) => meta_item,
             MetaItemInner::Lit(lit) => {
@@ -69,10 +72,10 @@ impl Predicate {
 
         match meta_item.kind {
             MetaItemKind::List(ref mis) => match predicate.name {
-                sym::any => Ok(Predicate::Any(Predicate::parse_sequence(mis)?)),
-                sym::all => Ok(Predicate::All(Predicate::parse_sequence(mis)?)),
+                sym::any => Ok(Predicate::Any(Predicate::parse_sequence(mis, generics)?)),
+                sym::all => Ok(Predicate::All(Predicate::parse_sequence(mis, generics)?)),
                 sym::not => match &**mis {
-                    [one] => Ok(Predicate::Not(Box::new(Predicate::parse(one)?))),
+                    [one] => Ok(Predicate::Not(Box::new(Predicate::parse(one, generics)?))),
                     [first, .., last] => Err(InvalidOnClause::ExpectedOnePredInNot {
                         span: first.span().to(last.span()),
                     }),
@@ -83,7 +86,7 @@ impl Predicate {
                 }
             },
             MetaItemKind::NameValue(MetaItemLit { symbol, .. }) => {
-                let name = Name::parse(predicate);
+                let name = Name::parse(predicate, generics)?;
                 let value = FilterFormatString::parse(symbol);
                 let kv = NameValue { name, value };
                 Ok(Predicate::Match(kv))
@@ -95,8 +98,11 @@ impl Predicate {
         }
     }
 
-    fn parse_sequence(sequence: &[MetaItemInner]) -> Result<Vec<Self>, InvalidOnClause> {
-        sequence.iter().map(Predicate::parse).collect()
+    fn parse_sequence(
+        sequence: &[MetaItemInner],
+        generics: &[Symbol],
+    ) -> Result<Vec<Self>, InvalidOnClause> {
+        sequence.iter().map(|item| Predicate::parse(item, generics)).collect()
     }
 
     fn eval(&self, eval: &mut impl FnMut(FlagOrNv<'_>) -> bool) -> bool {
@@ -156,14 +162,13 @@ enum Name {
 }
 
 impl Name {
-    fn parse(Ident { name, .. }: Ident) -> Self {
+    fn parse(Ident { name, span }: Ident, generics: &[Symbol]) -> Result<Self, InvalidOnClause> {
         match name {
-            sym::_Self | kw::SelfUpper => Name::SelfUpper,
-            sym::from_desugaring => Name::FromDesugaring,
-            sym::cause => Name::Cause,
-            // FIXME(mejrs) Perhaps we should start checking that
-            // this actually is a valid generic parameter?
-            generic => Name::GenericArg(generic),
+            kw::SelfUpper => Ok(Name::SelfUpper),
+            sym::from_desugaring => Ok(Name::FromDesugaring),
+            sym::cause => Ok(Name::Cause),
+            generic if generics.contains(&generic) => Ok(Name::GenericArg(generic)),
+            invalid_name => Err(InvalidOnClause::InvalidName { invalid_name, span }),
         }
     }
 }
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented_format.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented_format.rs
index ce170f820e1..7c1dfc1728f 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented_format.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented_format.rs
@@ -2,8 +2,8 @@ use std::fmt;
 use std::ops::Range;
 
 use errors::*;
-use rustc_middle::ty::TyCtxt;
 use rustc_middle::ty::print::TraitRefPrintSugared;
+use rustc_middle::ty::{GenericParamDefKind, TyCtxt};
 use rustc_parse_format::{
     Alignment, Argument, Count, FormatSpec, ParseError, ParseMode, Parser, Piece as RpfPiece,
     Position,
@@ -232,48 +232,16 @@ fn parse_arg<'tcx>(
 ) -> FormatArg {
     let (Ctx::RustcOnUnimplemented { tcx, trait_def_id }
     | Ctx::DiagnosticOnUnimplemented { tcx, trait_def_id }) = ctx;
-    let trait_name = tcx.item_ident(*trait_def_id);
-    let generics = tcx.generics_of(trait_def_id);
+
     let span = slice_span(input_span, arg.position_span.clone());
 
     match arg.position {
         // Something like "hello {name}"
         Position::ArgumentNamed(name) => match (ctx, Symbol::intern(name)) {
-            // accepted, but deprecated
-            (Ctx::RustcOnUnimplemented { .. }, sym::_Self) => {
-                warnings
-                    .push(FormatWarning::FutureIncompat { span, help: String::from("use {Self}") });
-                FormatArg::SelfUpper
-            }
-            (
-                Ctx::RustcOnUnimplemented { .. },
-                sym::from_desugaring
-                | sym::crate_local
-                | sym::direct
-                | sym::cause
-                | sym::float
-                | sym::integer_
-                | sym::integral,
-            ) => {
-                warnings.push(FormatWarning::FutureIncompat {
-                    span,
-                    help: String::from("don't use this in a format string"),
-                });
-                FormatArg::AsIs(String::new())
-            }
-
             // Only `#[rustc_on_unimplemented]` can use these
             (Ctx::RustcOnUnimplemented { .. }, sym::ItemContext) => FormatArg::ItemContext,
             (Ctx::RustcOnUnimplemented { .. }, sym::This) => FormatArg::This,
             (Ctx::RustcOnUnimplemented { .. }, sym::Trait) => FormatArg::Trait,
-            // `{ThisTraitsName}`. Some attrs in std use this, but I'd like to change it to the more general `{This}`
-            // because that'll be simpler to parse and extend in the future
-            (Ctx::RustcOnUnimplemented { .. }, name) if name == trait_name.name => {
-                warnings
-                    .push(FormatWarning::FutureIncompat { span, help: String::from("use {This}") });
-                FormatArg::This
-            }
-
             // Any attribute can use these
             (
                 Ctx::RustcOnUnimplemented { .. } | Ctx::DiagnosticOnUnimplemented { .. },
@@ -282,7 +250,10 @@ fn parse_arg<'tcx>(
             (
                 Ctx::RustcOnUnimplemented { .. } | Ctx::DiagnosticOnUnimplemented { .. },
                 generic_param,
-            ) if generics.own_params.iter().any(|param| param.name == generic_param) => {
+            ) if tcx.generics_of(trait_def_id).own_params.iter().any(|param| {
+                !matches!(param.kind, GenericParamDefKind::Lifetime) && param.name == generic_param
+            }) =>
+            {
                 FormatArg::GenericParam { generic_param }
             }
 
@@ -375,39 +346,4 @@ pub mod errors {
     #[diag(trait_selection_missing_options_for_on_unimplemented_attr)]
     #[help]
     pub struct MissingOptionsForOnUnimplementedAttr;
-
-    #[derive(LintDiagnostic)]
-    #[diag(trait_selection_ignored_diagnostic_option)]
-    pub struct IgnoredDiagnosticOption {
-        pub option_name: &'static str,
-        #[label]
-        pub span: Span,
-        #[label(trait_selection_other_label)]
-        pub prev_span: Span,
-    }
-
-    impl IgnoredDiagnosticOption {
-        pub fn maybe_emit_warning<'tcx>(
-            tcx: TyCtxt<'tcx>,
-            item_def_id: DefId,
-            new: Option<Span>,
-            old: Option<Span>,
-            option_name: &'static str,
-        ) {
-            if let (Some(new_item), Some(old_item)) = (new, old) {
-                if let Some(item_def_id) = item_def_id.as_local() {
-                    tcx.emit_node_span_lint(
-                        UNKNOWN_OR_MALFORMED_DIAGNOSTIC_ATTRIBUTES,
-                        tcx.local_def_id_to_hir_id(item_def_id),
-                        new_item,
-                        IgnoredDiagnosticOption {
-                            span: new_item,
-                            prev_span: old_item,
-                            option_name,
-                        },
-                    );
-                }
-            }
-        }
-    }
 }
diff --git a/compiler/rustc_trait_selection/src/errors.rs b/compiler/rustc_trait_selection/src/errors.rs
index 8ab4d795c45..779c861637a 100644
--- a/compiler/rustc_trait_selection/src/errors.rs
+++ b/compiler/rustc_trait_selection/src/errors.rs
@@ -72,6 +72,13 @@ pub enum InvalidOnClause {
         span: Span,
         invalid_flag: Symbol,
     },
+    #[diag(trait_selection_rustc_on_unimplemented_invalid_name, code = E0232)]
+    InvalidName {
+        #[primary_span]
+        #[label]
+        span: Span,
+        invalid_name: Symbol,
+    },
 }
 
 #[derive(Diagnostic)]
diff --git a/compiler/rustc_trait_selection/src/solve/delegate.rs b/compiler/rustc_trait_selection/src/solve/delegate.rs
index a60642b953c..b68a7845366 100644
--- a/compiler/rustc_trait_selection/src/solve/delegate.rs
+++ b/compiler/rustc_trait_selection/src/solve/delegate.rs
@@ -5,7 +5,7 @@ use rustc_hir::LangItem;
 use rustc_hir::def_id::{CRATE_DEF_ID, DefId};
 use rustc_infer::infer::canonical::query_response::make_query_region_constraints;
 use rustc_infer::infer::canonical::{
-    Canonical, CanonicalExt as _, CanonicalQueryInput, CanonicalVarInfo, CanonicalVarValues,
+    Canonical, CanonicalExt as _, CanonicalQueryInput, CanonicalVarKind, CanonicalVarValues,
 };
 use rustc_infer::infer::{InferCtxt, RegionVariableOrigin, SubregionOrigin, TyCtxtInferExt};
 use rustc_infer::traits::solve::Goal;
@@ -190,11 +190,11 @@ impl<'tcx> rustc_next_trait_solver::delegate::SolverDelegate for SolverDelegate<
 
     fn instantiate_canonical_var_with_infer(
         &self,
-        cv_info: CanonicalVarInfo<'tcx>,
+        kind: CanonicalVarKind<'tcx>,
         span: Span,
         universe_map: impl Fn(ty::UniverseIndex) -> ty::UniverseIndex,
     ) -> ty::GenericArg<'tcx> {
-        self.0.instantiate_canonical_var(span, cv_info, universe_map)
+        self.0.instantiate_canonical_var(span, kind, universe_map)
     }
 
     fn add_item_bounds_for_hidden_type(
diff --git a/compiler/rustc_trait_selection/src/solve/select.rs b/compiler/rustc_trait_selection/src/solve/select.rs
index 4fdaf740287..1f3168fafb1 100644
--- a/compiler/rustc_trait_selection/src/solve/select.rs
+++ b/compiler/rustc_trait_selection/src/solve/select.rs
@@ -5,7 +5,7 @@ use rustc_infer::traits::solve::inspect::ProbeKind;
 use rustc_infer::traits::solve::{CandidateSource, Certainty, Goal};
 use rustc_infer::traits::{
     BuiltinImplSource, ImplSource, ImplSourceUserDefinedData, Obligation, ObligationCause,
-    PolyTraitObligation, Selection, SelectionError, SelectionResult,
+    Selection, SelectionError, SelectionResult, TraitObligation,
 };
 use rustc_macros::extension;
 use rustc_middle::{bug, span_bug};
@@ -17,7 +17,7 @@ use crate::solve::inspect::{self, ProofTreeInferCtxtExt};
 impl<'tcx> InferCtxt<'tcx> {
     fn select_in_new_trait_solver(
         &self,
-        obligation: &PolyTraitObligation<'tcx>,
+        obligation: &TraitObligation<'tcx>,
     ) -> SelectionResult<'tcx, Selection<'tcx>> {
         assert!(self.next_trait_solver());
 
diff --git a/compiler/rustc_trait_selection/src/traits/mod.rs b/compiler/rustc_trait_selection/src/traits/mod.rs
index f73603c0053..a9bdb909bdc 100644
--- a/compiler/rustc_trait_selection/src/traits/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/mod.rs
@@ -540,10 +540,13 @@ pub fn try_evaluate_const<'tcx>(
         | ty::ConstKind::Placeholder(_)
         | ty::ConstKind::Expr(_) => Err(EvaluateConstErr::HasGenericsOrInfers),
         ty::ConstKind::Unevaluated(uv) => {
+            let opt_anon_const_kind =
+                (tcx.def_kind(uv.def) == DefKind::AnonConst).then(|| tcx.anon_const_kind(uv.def));
+
             // Postpone evaluation of constants that depend on generic parameters or
             // inference variables.
             //
-            // We use `TypingMode::PostAnalysis`  here which is not *technically* correct
+            // We use `TypingMode::PostAnalysis` here which is not *technically* correct
             // to be revealing opaque types here as borrowcheck has not run yet. However,
             // CTFE itself uses `TypingMode::PostAnalysis` unconditionally even during
             // typeck and not doing so has a lot of (undesirable) fallout (#101478, #119821).
@@ -551,65 +554,95 @@ pub fn try_evaluate_const<'tcx>(
             //
             // FIXME: `const_eval_resolve_for_typeck` should probably just modify the env itself
             // instead of having this logic here
-            let (args, typing_env) = if tcx.features().generic_const_exprs()
-                && uv.has_non_region_infer()
-            {
-                // `feature(generic_const_exprs)` causes anon consts to inherit all parent generics. This can cause
-                // inference variables and generic parameters to show up in `ty::Const` even though the anon const
-                // does not actually make use of them. We handle this case specially and attempt to evaluate anyway.
-                match tcx.thir_abstract_const(uv.def) {
-                    Ok(Some(ct)) => {
-                        let ct = tcx.expand_abstract_consts(ct.instantiate(tcx, uv.args));
-                        if let Err(e) = ct.error_reported() {
-                            return Err(EvaluateConstErr::EvaluationFailure(e));
-                        } else if ct.has_non_region_infer() || ct.has_non_region_param() {
-                            // If the anon const *does* actually use generic parameters or inference variables from
-                            // the generic arguments provided for it, then we should *not* attempt to evaluate it.
-                            return Err(EvaluateConstErr::HasGenericsOrInfers);
-                        } else {
-                            let args = replace_param_and_infer_args_with_placeholder(tcx, uv.args);
-                            let typing_env = infcx
-                                .typing_env(tcx.erase_regions(param_env))
-                                .with_post_analysis_normalized(tcx);
-                            (args, typing_env)
+            let (args, typing_env) = match opt_anon_const_kind {
+                // We handle `generic_const_exprs` separately as reasonable ways of handling constants in the type system
+                // completely fall apart under `generic_const_exprs` and makes this whole function Really hard to reason
+                // about if you have to consider gce whatsoever.
+                Some(ty::AnonConstKind::GCE) => {
+                    if uv.has_non_region_infer() || uv.has_non_region_param() {
+                        // `feature(generic_const_exprs)` causes anon consts to inherit all parent generics. This can cause
+                        // inference variables and generic parameters to show up in `ty::Const` even though the anon const
+                        // does not actually make use of them. We handle this case specially and attempt to evaluate anyway.
+                        match tcx.thir_abstract_const(uv.def) {
+                            Ok(Some(ct)) => {
+                                let ct = tcx.expand_abstract_consts(ct.instantiate(tcx, uv.args));
+                                if let Err(e) = ct.error_reported() {
+                                    return Err(EvaluateConstErr::EvaluationFailure(e));
+                                } else if ct.has_non_region_infer() || ct.has_non_region_param() {
+                                    // If the anon const *does* actually use generic parameters or inference variables from
+                                    // the generic arguments provided for it, then we should *not* attempt to evaluate it.
+                                    return Err(EvaluateConstErr::HasGenericsOrInfers);
+                                } else {
+                                    let args =
+                                        replace_param_and_infer_args_with_placeholder(tcx, uv.args);
+                                    let typing_env = infcx
+                                        .typing_env(tcx.erase_regions(param_env))
+                                        .with_post_analysis_normalized(tcx);
+                                    (args, typing_env)
+                                }
+                            }
+                            Err(_) | Ok(None) => {
+                                let args = GenericArgs::identity_for_item(tcx, uv.def);
+                                let typing_env = ty::TypingEnv::post_analysis(tcx, uv.def);
+                                (args, typing_env)
+                            }
                         }
+                    } else {
+                        let typing_env = infcx
+                            .typing_env(tcx.erase_regions(param_env))
+                            .with_post_analysis_normalized(tcx);
+                        (uv.args, typing_env)
                     }
-                    Err(_) | Ok(None) => {
-                        let args = GenericArgs::identity_for_item(tcx, uv.def);
-                        let typing_env = ty::TypingEnv::post_analysis(tcx, uv.def);
-                        (args, typing_env)
+                }
+                Some(ty::AnonConstKind::RepeatExprCount) => {
+                    if uv.has_non_region_infer() {
+                        // Diagnostics will sometimes replace the identity args of anon consts in
+                        // array repeat expr counts with inference variables so we have to handle this
+                        // even though it is not something we should ever actually encounter.
+                        //
+                        // Array repeat expr counts are allowed to syntactically use generic parameters
+                        // but must not actually depend on them in order to evalaute successfully. This means
+                        // that it is actually fine to evalaute them in their own environment rather than with
+                        // the actually provided generic arguments.
+                        tcx.dcx().delayed_bug("AnonConst with infer args but no error reported");
                     }
+
+                    // The generic args of repeat expr counts under `min_const_generics` are not supposed to
+                    // affect evaluation of the constant as this would make it a "truly" generic const arg.
+                    // To prevent this we discard all the generic arguments and evalaute with identity args
+                    // and in its own environment instead of the current environment we are normalizing in.
+                    let args = GenericArgs::identity_for_item(tcx, uv.def);
+                    let typing_env = ty::TypingEnv::post_analysis(tcx, uv.def);
+
+                    (args, typing_env)
+                }
+                _ => {
+                    // We are only dealing with "truly" generic/uninferred constants here:
+                    // - GCEConsts have been handled separately
+                    // - Repeat expr count back compat consts have also been handled separately
+                    // So we are free to simply defer evaluation here.
+                    //
+                    // FIXME: This assumes that `args` are normalized which is not necessarily true
+                    //
+                    // Const patterns are converted to type system constants before being
+                    // evaluated. However, we don't care about them here as pattern evaluation
+                    // logic does not go through type system normalization. If it did this would
+                    // be a backwards compatibility problem as we do not enforce "syntactic" non-
+                    // usage of generic parameters like we do here.
+                    if uv.args.has_non_region_param() || uv.args.has_non_region_infer() {
+                        return Err(EvaluateConstErr::HasGenericsOrInfers);
+                    }
+
+                    let typing_env = infcx
+                        .typing_env(tcx.erase_regions(param_env))
+                        .with_post_analysis_normalized(tcx);
+                    (uv.args, typing_env)
                 }
-            } else if tcx.def_kind(uv.def) == DefKind::AnonConst && uv.has_non_region_infer() {
-                // FIXME: remove this when `const_evaluatable_unchecked` is a hard error.
-                //
-                // Diagnostics will sometimes replace the identity args of anon consts in
-                // array repeat expr counts with inference variables so we have to handle this
-                // even though it is not something we should ever actually encounter.
-                //
-                // Array repeat expr counts are allowed to syntactically use generic parameters
-                // but must not actually depend on them in order to evalaute successfully. This means
-                // that it is actually fine to evalaute them in their own environment rather than with
-                // the actually provided generic arguments.
-                tcx.dcx().delayed_bug(
-                    "Encountered anon const with inference variable args but no error reported",
-                );
-
-                let args = GenericArgs::identity_for_item(tcx, uv.def);
-                let typing_env = ty::TypingEnv::post_analysis(tcx, uv.def);
-                (args, typing_env)
-            } else {
-                // FIXME: This codepath is reachable under `associated_const_equality` and in the
-                // future will be reachable by `min_generic_const_args`. We should handle inference
-                // variables and generic parameters properly instead of doing nothing.
-                let typing_env = infcx
-                    .typing_env(tcx.erase_regions(param_env))
-                    .with_post_analysis_normalized(tcx);
-                (uv.args, typing_env)
             };
-            let uv = ty::UnevaluatedConst::new(uv.def, args);
 
+            let uv = ty::UnevaluatedConst::new(uv.def, args);
             let erased_uv = tcx.erase_regions(uv);
+
             use rustc_middle::mir::interpret::ErrorHandled;
             match tcx.const_eval_resolve_for_typeck(typing_env, erased_uv, DUMMY_SP) {
                 Ok(Ok(val)) => Ok(ty::Const::new_value(
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs
index ca58da5ca6d..ed0f34b5aa9 100644
--- a/compiler/rustc_trait_selection/src/traits/project.rs
+++ b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -378,6 +378,7 @@ pub(super) fn opt_normalize_projection_term<'a, 'b, 'tcx>(
             term: projected_term,
             obligations: mut projected_obligations,
         })) => {
+            debug!("opt_normalize_projection_type: progress");
             // if projection succeeded, then what we get out of this
             // is also non-normalized (consider: it was derived from
             // an impl, where-clause etc) and hence we must
@@ -408,6 +409,7 @@ pub(super) fn opt_normalize_projection_term<'a, 'b, 'tcx>(
             Ok(Some(result.value))
         }
         Ok(Projected::NoProgress(projected_ty)) => {
+            debug!("opt_normalize_projection_type: no progress");
             let result =
                 Normalized { value: projected_ty, obligations: PredicateObligations::new() };
             infcx.inner.borrow_mut().projection_cache().insert_term(cache_key, result.clone());
@@ -621,8 +623,17 @@ struct Progress<'tcx> {
 }
 
 impl<'tcx> Progress<'tcx> {
-    fn error(tcx: TyCtxt<'tcx>, guar: ErrorGuaranteed) -> Self {
-        Progress { term: Ty::new_error(tcx, guar).into(), obligations: PredicateObligations::new() }
+    fn error_for_term(
+        tcx: TyCtxt<'tcx>,
+        alias_term: ty::AliasTerm<'tcx>,
+        guar: ErrorGuaranteed,
+    ) -> Self {
+        let err_term = if alias_term.kind(tcx).is_type() {
+            Ty::new_error(tcx, guar).into()
+        } else {
+            ty::Const::new_error(tcx, guar).into()
+        };
+        Progress { term: err_term, obligations: PredicateObligations::new() }
     }
 
     fn with_addl_obligations(mut self, mut obligations: PredicateObligations<'tcx>) -> Self {
@@ -650,7 +661,11 @@ fn project<'cx, 'tcx>(
     }
 
     if let Err(guar) = obligation.predicate.error_reported() {
-        return Ok(Projected::Progress(Progress::error(selcx.tcx(), guar)));
+        return Ok(Projected::Progress(Progress::error_for_term(
+            selcx.tcx(),
+            obligation.predicate,
+            guar,
+        )));
     }
 
     let mut candidates = ProjectionCandidateSet::None;
@@ -1965,7 +1980,13 @@ fn confirm_impl_candidate<'cx, 'tcx>(
     let param_env = obligation.param_env;
     let assoc_term = match specialization_graph::assoc_def(tcx, impl_def_id, assoc_item_id) {
         Ok(assoc_term) => assoc_term,
-        Err(guar) => return Ok(Projected::Progress(Progress::error(tcx, guar))),
+        Err(guar) => {
+            return Ok(Projected::Progress(Progress::error_for_term(
+                tcx,
+                obligation.predicate,
+                guar,
+            )));
+        }
     };
 
     // This means that the impl is missing a definition for the
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index 44a76f6e083..2be799735a8 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -265,9 +265,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         &mut self,
         obligation: &PolyTraitObligation<'tcx>,
     ) -> SelectionResult<'tcx, Selection<'tcx>> {
-        if self.infcx.next_trait_solver() {
-            return self.infcx.select_in_new_trait_solver(obligation);
-        }
+        assert!(!self.infcx.next_trait_solver());
 
         let candidate = match self.select_from_obligation(obligation) {
             Err(SelectionError::Overflow(OverflowError::Canonical)) => {
@@ -299,6 +297,10 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         &mut self,
         obligation: &TraitObligation<'tcx>,
     ) -> SelectionResult<'tcx, Selection<'tcx>> {
+        if self.infcx.next_trait_solver() {
+            return self.infcx.select_in_new_trait_solver(obligation);
+        }
+
         self.poly_select(&Obligation {
             cause: obligation.cause.clone(),
             param_env: obligation.param_env,
@@ -2866,7 +2868,7 @@ fn rebind_coroutine_witness_types<'tcx>(
     let shifted_coroutine_types =
         tcx.shift_bound_var_indices(bound_vars.len(), bound_coroutine_types.skip_binder());
     ty::Binder::bind_with_vars(
-        ty::EarlyBinder::bind(shifted_coroutine_types.to_vec()).instantiate(tcx, args),
+        ty::EarlyBinder::bind(shifted_coroutine_types.types.to_vec()).instantiate(tcx, args),
         tcx.mk_bound_variable_kinds_from_iter(
             bound_vars.iter().chain(bound_coroutine_types.bound_vars()),
         ),
diff --git a/compiler/rustc_traits/src/coroutine_witnesses.rs b/compiler/rustc_traits/src/coroutine_witnesses.rs
new file mode 100644
index 00000000000..447e13126cc
--- /dev/null
+++ b/compiler/rustc_traits/src/coroutine_witnesses.rs
@@ -0,0 +1,37 @@
+use rustc_hir::def_id::DefId;
+use rustc_middle::ty::{self, TyCtxt, fold_regions};
+
+/// Return the set of types that should be taken into account when checking
+/// trait bounds on a coroutine's internal state. This properly replaces
+/// `ReErased` with new existential bound lifetimes.
+pub(crate) fn coroutine_hidden_types<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    def_id: DefId,
+) -> ty::EarlyBinder<'tcx, ty::Binder<'tcx, ty::CoroutineWitnessTypes<TyCtxt<'tcx>>>> {
+    let coroutine_layout = tcx.mir_coroutine_witnesses(def_id);
+    let mut vars = vec![];
+    let bound_tys = tcx.mk_type_list_from_iter(
+        coroutine_layout
+            .as_ref()
+            .map_or_else(|| [].iter(), |l| l.field_tys.iter())
+            .filter(|decl| !decl.ignore_for_traits)
+            .map(|decl| {
+                let ty = fold_regions(tcx, decl.ty, |re, debruijn| {
+                    assert_eq!(re, tcx.lifetimes.re_erased);
+                    let var = ty::BoundVar::from_usize(vars.len());
+                    vars.push(ty::BoundVariableKind::Region(ty::BoundRegionKind::Anon));
+                    ty::Region::new_bound(
+                        tcx,
+                        debruijn,
+                        ty::BoundRegion { var, kind: ty::BoundRegionKind::Anon },
+                    )
+                });
+                ty
+            }),
+    );
+
+    ty::EarlyBinder::bind(ty::Binder::bind_with_vars(
+        ty::CoroutineWitnessTypes { types: bound_tys },
+        tcx.mk_bound_variable_kinds(&vars),
+    ))
+}
diff --git a/compiler/rustc_traits/src/lib.rs b/compiler/rustc_traits/src/lib.rs
index 697c8391803..32d8c3f58e0 100644
--- a/compiler/rustc_traits/src/lib.rs
+++ b/compiler/rustc_traits/src/lib.rs
@@ -5,6 +5,7 @@
 // tidy-alphabetical-end
 
 mod codegen;
+mod coroutine_witnesses;
 mod dropck_outlives;
 mod evaluate_obligation;
 mod implied_outlives_bounds;
@@ -24,4 +25,5 @@ pub fn provide(p: &mut Providers) {
     normalize_erasing_regions::provide(p);
     type_op::provide(p);
     p.codegen_select_candidate = codegen::codegen_select_candidate;
+    p.coroutine_hidden_types = coroutine_witnesses::coroutine_hidden_types;
 }
diff --git a/compiler/rustc_type_ir/src/canonical.rs b/compiler/rustc_type_ir/src/canonical.rs
index 67b67df4b28..2b1b0617cef 100644
--- a/compiler/rustc_type_ir/src/canonical.rs
+++ b/compiler/rustc_type_ir/src/canonical.rs
@@ -41,7 +41,7 @@ pub struct CanonicalQueryInput<I: Interner, V> {
 pub struct Canonical<I: Interner, V> {
     pub value: V,
     pub max_universe: UniverseIndex,
-    pub variables: I::CanonicalVars,
+    pub variables: I::CanonicalVarKinds,
 }
 
 impl<I: Interner, V> Canonical<I, V> {
@@ -89,63 +89,6 @@ impl<I: Interner, V: fmt::Display> fmt::Display for Canonical<I, V> {
 /// a copy of the canonical value in some other inference context,
 /// with fresh inference variables replacing the canonical values.
 #[derive_where(Clone, Copy, Hash, PartialEq, Eq, Debug; I: Interner)]
-#[derive(TypeVisitable_Generic, TypeFoldable_Generic)]
-#[cfg_attr(
-    feature = "nightly",
-    derive(Decodable_NoContext, Encodable_NoContext, HashStable_NoContext)
-)]
-pub struct CanonicalVarInfo<I: Interner> {
-    pub kind: CanonicalVarKind<I>,
-}
-
-impl<I: Interner> CanonicalVarInfo<I> {
-    pub fn universe(self) -> UniverseIndex {
-        self.kind.universe()
-    }
-
-    #[must_use]
-    pub fn with_updated_universe(self, ui: UniverseIndex) -> CanonicalVarInfo<I> {
-        CanonicalVarInfo { kind: self.kind.with_updated_universe(ui) }
-    }
-
-    pub fn is_existential(&self) -> bool {
-        match self.kind {
-            CanonicalVarKind::Ty(_) => true,
-            CanonicalVarKind::PlaceholderTy(_) => false,
-            CanonicalVarKind::Region(_) => true,
-            CanonicalVarKind::PlaceholderRegion(..) => false,
-            CanonicalVarKind::Const(_) => true,
-            CanonicalVarKind::PlaceholderConst(_) => false,
-        }
-    }
-
-    pub fn is_region(&self) -> bool {
-        match self.kind {
-            CanonicalVarKind::Region(_) | CanonicalVarKind::PlaceholderRegion(_) => true,
-            CanonicalVarKind::Ty(_)
-            | CanonicalVarKind::PlaceholderTy(_)
-            | CanonicalVarKind::Const(_)
-            | CanonicalVarKind::PlaceholderConst(_) => false,
-        }
-    }
-
-    pub fn expect_placeholder_index(self) -> usize {
-        match self.kind {
-            CanonicalVarKind::Ty(_) | CanonicalVarKind::Region(_) | CanonicalVarKind::Const(_) => {
-                panic!("expected placeholder: {self:?}")
-            }
-
-            CanonicalVarKind::PlaceholderRegion(placeholder) => placeholder.var().as_usize(),
-            CanonicalVarKind::PlaceholderTy(placeholder) => placeholder.var().as_usize(),
-            CanonicalVarKind::PlaceholderConst(placeholder) => placeholder.var().as_usize(),
-        }
-    }
-}
-
-/// Describes the "kind" of the canonical variable. This is a "kind"
-/// in the type-theory sense of the term -- i.e., a "meta" type system
-/// that analyzes type-like values.
-#[derive_where(Clone, Copy, Hash, PartialEq, Eq, Debug; I: Interner)]
 #[cfg_attr(
     feature = "nightly",
     derive(Decodable_NoContext, Encodable_NoContext, HashStable_NoContext)
@@ -214,6 +157,39 @@ impl<I: Interner> CanonicalVarKind<I> {
             }
         }
     }
+
+    pub fn is_existential(self) -> bool {
+        match self {
+            CanonicalVarKind::Ty(_) => true,
+            CanonicalVarKind::PlaceholderTy(_) => false,
+            CanonicalVarKind::Region(_) => true,
+            CanonicalVarKind::PlaceholderRegion(..) => false,
+            CanonicalVarKind::Const(_) => true,
+            CanonicalVarKind::PlaceholderConst(_) => false,
+        }
+    }
+
+    pub fn is_region(self) -> bool {
+        match self {
+            CanonicalVarKind::Region(_) | CanonicalVarKind::PlaceholderRegion(_) => true,
+            CanonicalVarKind::Ty(_)
+            | CanonicalVarKind::PlaceholderTy(_)
+            | CanonicalVarKind::Const(_)
+            | CanonicalVarKind::PlaceholderConst(_) => false,
+        }
+    }
+
+    pub fn expect_placeholder_index(self) -> usize {
+        match self {
+            CanonicalVarKind::Ty(_) | CanonicalVarKind::Region(_) | CanonicalVarKind::Const(_) => {
+                panic!("expected placeholder: {self:?}")
+            }
+
+            CanonicalVarKind::PlaceholderRegion(placeholder) => placeholder.var().as_usize(),
+            CanonicalVarKind::PlaceholderTy(placeholder) => placeholder.var().as_usize(),
+            CanonicalVarKind::PlaceholderConst(placeholder) => placeholder.var().as_usize(),
+        }
+    }
 }
 
 /// Rust actually has more than one category of type variables;
@@ -306,11 +282,11 @@ impl<I: Interner> CanonicalVarValues<I> {
 
     // Given a list of canonical variables, construct a set of values which are
     // the identity response.
-    pub fn make_identity(cx: I, infos: I::CanonicalVars) -> CanonicalVarValues<I> {
+    pub fn make_identity(cx: I, infos: I::CanonicalVarKinds) -> CanonicalVarValues<I> {
         CanonicalVarValues {
             var_values: cx.mk_args_from_iter(infos.iter().enumerate().map(
-                |(i, info)| -> I::GenericArg {
-                    match info.kind {
+                |(i, kind)| -> I::GenericArg {
+                    match kind {
                         CanonicalVarKind::Ty(_) | CanonicalVarKind::PlaceholderTy(_) => {
                             Ty::new_anon_bound(cx, ty::INNERMOST, ty::BoundVar::from_usize(i))
                                 .into()
diff --git a/compiler/rustc_type_ir/src/interner.rs b/compiler/rustc_type_ir/src/interner.rs
index 0fd2d9f3ad3..7e88114df46 100644
--- a/compiler/rustc_type_ir/src/interner.rs
+++ b/compiler/rustc_type_ir/src/interner.rs
@@ -64,13 +64,16 @@ pub trait Interner:
         + TypeVisitable<Self>
         + SliceLike<Item = Self::LocalDefId>;
 
-    type CanonicalVars: Copy
+    type CanonicalVarKinds: Copy
         + Debug
         + Hash
         + Eq
-        + SliceLike<Item = ty::CanonicalVarInfo<Self>>
+        + SliceLike<Item = ty::CanonicalVarKind<Self>>
         + Default;
-    fn mk_canonical_var_infos(self, infos: &[ty::CanonicalVarInfo<Self>]) -> Self::CanonicalVars;
+    fn mk_canonical_var_kinds(
+        self,
+        kinds: &[ty::CanonicalVarKind<Self>],
+    ) -> Self::CanonicalVarKinds;
 
     type ExternalConstraints: Copy
         + Debug
@@ -210,7 +213,7 @@ pub trait Interner:
     fn coroutine_hidden_types(
         self,
         def_id: Self::DefId,
-    ) -> ty::EarlyBinder<Self, ty::Binder<Self, Self::Tys>>;
+    ) -> ty::EarlyBinder<Self, ty::Binder<Self, ty::CoroutineWitnessTypes<Self>>>;
 
     fn fn_sig(
         self,
diff --git a/compiler/rustc_type_ir/src/ty_kind.rs b/compiler/rustc_type_ir/src/ty_kind.rs
index cf2e4284d10..0cd98b5aa53 100644
--- a/compiler/rustc_type_ir/src/ty_kind.rs
+++ b/compiler/rustc_type_ir/src/ty_kind.rs
@@ -1163,3 +1163,13 @@ pub struct FnHeader<I: Interner> {
     pub safety: I::Safety,
     pub abi: I::Abi,
 }
+
+#[derive_where(Clone, Copy, Debug, PartialEq, Eq, Hash; I: Interner)]
+#[cfg_attr(
+    feature = "nightly",
+    derive(Encodable_NoContext, Decodable_NoContext, HashStable_NoContext)
+)]
+#[derive(TypeVisitable_Generic, TypeFoldable_Generic, Lift_Generic)]
+pub struct CoroutineWitnessTypes<I: Interner> {
+    pub types: I::Tys,
+}
diff --git a/library/core/src/array/mod.rs b/library/core/src/array/mod.rs
index 4476e3f7923..221ca91e005 100644
--- a/library/core/src/array/mod.rs
+++ b/library/core/src/array/mod.rs
@@ -588,7 +588,7 @@ impl<T, const N: usize> [T; N] {
     /// Returns a mutable slice containing the entire array. Equivalent to
     /// `&mut s[..]`.
     #[stable(feature = "array_as_slice", since = "1.57.0")]
-    #[rustc_const_unstable(feature = "const_array_as_mut_slice", issue = "133333")]
+    #[rustc_const_stable(feature = "const_array_as_mut_slice", since = "CURRENT_RUSTC_VERSION")]
     pub const fn as_mut_slice(&mut self) -> &mut [T] {
         self
     }
diff --git a/library/core/src/convert/mod.rs b/library/core/src/convert/mod.rs
index c542a28beb8..d86dc24fb57 100644
--- a/library/core/src/convert/mod.rs
+++ b/library/core/src/convert/mod.rs
@@ -575,7 +575,7 @@ pub trait Into<T>: Sized {
 #[rustc_diagnostic_item = "From"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_on_unimplemented(on(
-    all(_Self = "&str", T = "alloc::string::String"),
+    all(Self = "&str", T = "alloc::string::String"),
     note = "to coerce a `{T}` into a `{Self}`, use `&*` as a prefix",
 ))]
 #[doc(search_unbox)]
diff --git a/library/core/src/ffi/c_str.rs b/library/core/src/ffi/c_str.rs
index ac07c645c01..825402116e5 100644
--- a/library/core/src/ffi/c_str.rs
+++ b/library/core/src/ffi/c_str.rs
@@ -511,13 +511,8 @@ impl CStr {
     /// # Examples
     ///
     /// ```
-    /// use std::ffi::CStr;
-    ///
-    /// let cstr = CStr::from_bytes_with_nul(b"foo\0").unwrap();
-    /// assert_eq!(cstr.count_bytes(), 3);
-    ///
-    /// let cstr = CStr::from_bytes_with_nul(b"\0").unwrap();
-    /// assert_eq!(cstr.count_bytes(), 0);
+    /// assert_eq!(c"foo".count_bytes(), 3);
+    /// assert_eq!(c"".count_bytes(), 0);
     /// ```
     #[inline]
     #[must_use]
@@ -533,19 +528,8 @@ impl CStr {
     /// # Examples
     ///
     /// ```
-    /// use std::ffi::CStr;
-    /// # use std::ffi::FromBytesWithNulError;
-    ///
-    /// # fn main() { test().unwrap(); }
-    /// # fn test() -> Result<(), FromBytesWithNulError> {
-    /// let cstr = CStr::from_bytes_with_nul(b"foo\0")?;
-    /// assert!(!cstr.is_empty());
-    ///
-    /// let empty_cstr = CStr::from_bytes_with_nul(b"\0")?;
-    /// assert!(empty_cstr.is_empty());
+    /// assert!(!c"foo".is_empty());
     /// assert!(c"".is_empty());
-    /// # Ok(())
-    /// # }
     /// ```
     #[inline]
     #[stable(feature = "cstr_is_empty", since = "1.71.0")]
@@ -569,10 +553,7 @@ impl CStr {
     /// # Examples
     ///
     /// ```
-    /// use std::ffi::CStr;
-    ///
-    /// let cstr = CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed");
-    /// assert_eq!(cstr.to_bytes(), b"foo");
+    /// assert_eq!(c"foo".to_bytes(), b"foo");
     /// ```
     #[inline]
     #[must_use = "this returns the result of the operation, \
@@ -598,10 +579,7 @@ impl CStr {
     /// # Examples
     ///
     /// ```
-    /// use std::ffi::CStr;
-    ///
-    /// let cstr = CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed");
-    /// assert_eq!(cstr.to_bytes_with_nul(), b"foo\0");
+    /// assert_eq!(c"foo".to_bytes_with_nul(), b"foo\0");
     /// ```
     #[inline]
     #[must_use = "this returns the result of the operation, \
@@ -623,10 +601,8 @@ impl CStr {
     ///
     /// ```
     /// #![feature(cstr_bytes)]
-    /// use std::ffi::CStr;
     ///
-    /// let cstr = CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed");
-    /// assert!(cstr.bytes().eq(*b"foo"));
+    /// assert!(c"foo".bytes().eq(*b"foo"));
     /// ```
     #[inline]
     #[unstable(feature = "cstr_bytes", issue = "112115")]
@@ -645,10 +621,7 @@ impl CStr {
     /// # Examples
     ///
     /// ```
-    /// use std::ffi::CStr;
-    ///
-    /// let cstr = CStr::from_bytes_with_nul(b"foo\0").expect("CStr::from_bytes_with_nul failed");
-    /// assert_eq!(cstr.to_str(), Ok("foo"));
+    /// assert_eq!(c"foo".to_str(), Ok("foo"));
     /// ```
     #[stable(feature = "cstr_to_str", since = "1.4.0")]
     #[rustc_const_stable(feature = "const_cstr_methods", since = "1.72.0")]
diff --git a/library/core/src/fmt/mod.rs b/library/core/src/fmt/mod.rs
index 4f7f8a5b84d..5978cb660f6 100644
--- a/library/core/src/fmt/mod.rs
+++ b/library/core/src/fmt/mod.rs
@@ -856,10 +856,10 @@ impl Display for Arguments<'_> {
     on(
         crate_local,
         label = "`{Self}` cannot be formatted using `{{:?}}`",
-        note = "add `#[derive(Debug)]` to `{Self}` or manually `impl {Debug} for {Self}`"
+        note = "add `#[derive(Debug)]` to `{Self}` or manually `impl {This} for {Self}`"
     ),
-    message = "`{Self}` doesn't implement `{Debug}`",
-    label = "`{Self}` cannot be formatted using `{{:?}}` because it doesn't implement `{Debug}`"
+    message = "`{Self}` doesn't implement `{This}`",
+    label = "`{Self}` cannot be formatted using `{{:?}}` because it doesn't implement `{This}`"
 )]
 #[doc(alias = "{:?}")]
 #[rustc_diagnostic_item = "Debug"]
@@ -969,12 +969,12 @@ pub use macros::Debug;
 /// ```
 #[rustc_on_unimplemented(
     on(
-        any(_Self = "std::path::Path", _Self = "std::path::PathBuf"),
+        any(Self = "std::path::Path", Self = "std::path::PathBuf"),
         label = "`{Self}` cannot be formatted with the default formatter; call `.display()` on it",
         note = "call `.display()` or `.to_string_lossy()` to safely print paths, \
                 as they may contain non-Unicode data"
     ),
-    message = "`{Self}` doesn't implement `{Display}`",
+    message = "`{Self}` doesn't implement `{This}`",
     label = "`{Self}` cannot be formatted with the default formatter",
     note = "in format strings you may be able to use `{{:?}}` (or {{:#?}} for pretty-print) instead"
 )]
diff --git a/library/core/src/hint.rs b/library/core/src/hint.rs
index 6eefb304689..8ea9de7e9e5 100644
--- a/library/core/src/hint.rs
+++ b/library/core/src/hint.rs
@@ -231,7 +231,7 @@ pub const unsafe fn assert_unchecked(cond: bool) {
 ///
 /// # Examples
 ///
-/// ```
+/// ```ignore-wasm
 /// use std::sync::atomic::{AtomicBool, Ordering};
 /// use std::sync::Arc;
 /// use std::{hint, thread};
diff --git a/library/core/src/intrinsics/mod.rs b/library/core/src/intrinsics/mod.rs
index 23bafa778bc..e9fa3b1b3f6 100644
--- a/library/core/src/intrinsics/mod.rs
+++ b/library/core/src/intrinsics/mod.rs
@@ -2296,12 +2296,6 @@ pub fn round_ties_even_f16(x: f16) -> f16;
 #[rustc_nounwind]
 pub fn round_ties_even_f32(x: f32) -> f32;
 
-/// Provided for compatibility with stdarch. DO NOT USE.
-#[inline(always)]
-pub unsafe fn rintf32(x: f32) -> f32 {
-    round_ties_even_f32(x)
-}
-
 /// Returns the nearest integer to an `f64`. Rounds half-way cases to the number with an even
 /// least significant digit.
 ///
@@ -2311,12 +2305,6 @@ pub unsafe fn rintf32(x: f32) -> f32 {
 #[rustc_nounwind]
 pub fn round_ties_even_f64(x: f64) -> f64;
 
-/// Provided for compatibility with stdarch. DO NOT USE.
-#[inline(always)]
-pub unsafe fn rintf64(x: f64) -> f64 {
-    round_ties_even_f64(x)
-}
-
 /// Returns the nearest integer to an `f128`. Rounds half-way cases to the number with an even
 /// least significant digit.
 ///
diff --git a/library/core/src/iter/traits/collect.rs b/library/core/src/iter/traits/collect.rs
index 97bb21c8a36..3bc9cff8072 100644
--- a/library/core/src/iter/traits/collect.rs
+++ b/library/core/src/iter/traits/collect.rs
@@ -97,32 +97,32 @@ use super::TrustedLen;
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_on_unimplemented(
     on(
-        _Self = "&[{A}]",
+        Self = "&[{A}]",
         message = "a slice of type `{Self}` cannot be built since we need to store the elements somewhere",
         label = "try explicitly collecting into a `Vec<{A}>`",
     ),
     on(
-        all(A = "{integer}", any(_Self = "&[{integral}]",)),
+        all(A = "{integer}", any(Self = "&[{integral}]",)),
         message = "a slice of type `{Self}` cannot be built since we need to store the elements somewhere",
         label = "try explicitly collecting into a `Vec<{A}>`",
     ),
     on(
-        _Self = "[{A}]",
+        Self = "[{A}]",
         message = "a slice of type `{Self}` cannot be built since `{Self}` has no definite size",
         label = "try explicitly collecting into a `Vec<{A}>`",
     ),
     on(
-        all(A = "{integer}", any(_Self = "[{integral}]",)),
+        all(A = "{integer}", any(Self = "[{integral}]",)),
         message = "a slice of type `{Self}` cannot be built since `{Self}` has no definite size",
         label = "try explicitly collecting into a `Vec<{A}>`",
     ),
     on(
-        _Self = "[{A}; _]",
+        Self = "[{A}; _]",
         message = "an array of type `{Self}` cannot be built directly from an iterator",
         label = "try collecting into a `Vec<{A}>`, then using `.try_into()`",
     ),
     on(
-        all(A = "{integer}", any(_Self = "[{integral}; _]",)),
+        all(A = "{integer}", any(Self = "[{integral}; _]",)),
         message = "an array of type `{Self}` cannot be built directly from an iterator",
         label = "try collecting into a `Vec<{A}>`, then using `.try_into()`",
     ),
@@ -239,41 +239,38 @@ pub trait FromIterator<A>: Sized {
 #[rustc_diagnostic_item = "IntoIterator"]
 #[rustc_on_unimplemented(
     on(
-        _Self = "core::ops::range::RangeTo<Idx>",
+        Self = "core::ops::range::RangeTo<Idx>",
         label = "if you meant to iterate until a value, add a starting value",
         note = "`..end` is a `RangeTo`, which cannot be iterated on; you might have meant to have a \
               bounded `Range`: `0..end`"
     ),
     on(
-        _Self = "core::ops::range::RangeToInclusive<Idx>",
+        Self = "core::ops::range::RangeToInclusive<Idx>",
         label = "if you meant to iterate until a value (including it), add a starting value",
         note = "`..=end` is a `RangeToInclusive`, which cannot be iterated on; you might have meant \
               to have a bounded `RangeInclusive`: `0..=end`"
     ),
     on(
-        _Self = "[]",
+        Self = "[]",
         label = "`{Self}` is not an iterator; try calling `.into_iter()` or `.iter()`"
     ),
-    on(_Self = "&[]", label = "`{Self}` is not an iterator; try calling `.iter()`"),
+    on(Self = "&[]", label = "`{Self}` is not an iterator; try calling `.iter()`"),
     on(
-        _Self = "alloc::vec::Vec<T, A>",
+        Self = "alloc::vec::Vec<T, A>",
         label = "`{Self}` is not an iterator; try calling `.into_iter()` or `.iter()`"
     ),
+    on(Self = "&str", label = "`{Self}` is not an iterator; try calling `.chars()` or `.bytes()`"),
     on(
-        _Self = "&str",
+        Self = "alloc::string::String",
         label = "`{Self}` is not an iterator; try calling `.chars()` or `.bytes()`"
     ),
     on(
-        _Self = "alloc::string::String",
-        label = "`{Self}` is not an iterator; try calling `.chars()` or `.bytes()`"
-    ),
-    on(
-        _Self = "{integral}",
+        Self = "{integral}",
         note = "if you want to iterate between `start` until a value `end`, use the exclusive range \
               syntax `start..end` or the inclusive range syntax `start..=end`"
     ),
     on(
-        _Self = "{float}",
+        Self = "{float}",
         note = "if you want to iterate between `start` until a value `end`, use the exclusive range \
               syntax `start..end` or the inclusive range syntax `start..=end`"
     ),
diff --git a/library/core/src/iter/traits/iterator.rs b/library/core/src/iter/traits/iterator.rs
index d1e71f0e60f..cf85bdb1352 100644
--- a/library/core/src/iter/traits/iterator.rs
+++ b/library/core/src/iter/traits/iterator.rs
@@ -22,11 +22,11 @@ fn _assert_is_dyn_compatible(_: &dyn Iterator<Item = ()>) {}
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_on_unimplemented(
     on(
-        _Self = "core::ops::range::RangeTo<Idx>",
+        Self = "core::ops::range::RangeTo<Idx>",
         note = "you might have meant to use a bounded `Range`"
     ),
     on(
-        _Self = "core::ops::range::RangeToInclusive<Idx>",
+        Self = "core::ops::range::RangeToInclusive<Idx>",
         note = "you might have meant to use a bounded `RangeInclusive`"
     ),
     label = "`{Self}` is not an iterator",
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index b76213fdd41..c49513f7a6d 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -158,7 +158,6 @@
 #![feature(intra_doc_pointers)]
 #![feature(intrinsics)]
 #![feature(lang_items)]
-#![feature(let_chains)]
 #![feature(link_llvm_intrinsics)]
 #![feature(macro_metavar_expr)]
 #![feature(marker_trait_attr)]
diff --git a/library/core/src/marker.rs b/library/core/src/marker.rs
index f33b8d188d8..700fb0f386e 100644
--- a/library/core/src/marker.rs
+++ b/library/core/src/marker.rs
@@ -550,72 +550,72 @@ pub trait BikeshedGuaranteedNoDrop {}
 #[lang = "sync"]
 #[rustc_on_unimplemented(
     on(
-        _Self = "core::cell::once::OnceCell<T>",
+        Self = "core::cell::once::OnceCell<T>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::OnceLock` instead"
     ),
     on(
-        _Self = "core::cell::Cell<u8>",
+        Self = "core::cell::Cell<u8>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicU8` instead",
     ),
     on(
-        _Self = "core::cell::Cell<u16>",
+        Self = "core::cell::Cell<u16>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicU16` instead",
     ),
     on(
-        _Self = "core::cell::Cell<u32>",
+        Self = "core::cell::Cell<u32>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicU32` instead",
     ),
     on(
-        _Self = "core::cell::Cell<u64>",
+        Self = "core::cell::Cell<u64>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicU64` instead",
     ),
     on(
-        _Self = "core::cell::Cell<usize>",
+        Self = "core::cell::Cell<usize>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicUsize` instead",
     ),
     on(
-        _Self = "core::cell::Cell<i8>",
+        Self = "core::cell::Cell<i8>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicI8` instead",
     ),
     on(
-        _Self = "core::cell::Cell<i16>",
+        Self = "core::cell::Cell<i16>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicI16` instead",
     ),
     on(
-        _Self = "core::cell::Cell<i32>",
+        Self = "core::cell::Cell<i32>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicI32` instead",
     ),
     on(
-        _Self = "core::cell::Cell<i64>",
+        Self = "core::cell::Cell<i64>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicI64` instead",
     ),
     on(
-        _Self = "core::cell::Cell<isize>",
+        Self = "core::cell::Cell<isize>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicIsize` instead",
     ),
     on(
-        _Self = "core::cell::Cell<bool>",
+        Self = "core::cell::Cell<bool>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` or `std::sync::atomic::AtomicBool` instead",
     ),
     on(
         all(
-            _Self = "core::cell::Cell<T>",
-            not(_Self = "core::cell::Cell<u8>"),
-            not(_Self = "core::cell::Cell<u16>"),
-            not(_Self = "core::cell::Cell<u32>"),
-            not(_Self = "core::cell::Cell<u64>"),
-            not(_Self = "core::cell::Cell<usize>"),
-            not(_Self = "core::cell::Cell<i8>"),
-            not(_Self = "core::cell::Cell<i16>"),
-            not(_Self = "core::cell::Cell<i32>"),
-            not(_Self = "core::cell::Cell<i64>"),
-            not(_Self = "core::cell::Cell<isize>"),
-            not(_Self = "core::cell::Cell<bool>")
+            Self = "core::cell::Cell<T>",
+            not(Self = "core::cell::Cell<u8>"),
+            not(Self = "core::cell::Cell<u16>"),
+            not(Self = "core::cell::Cell<u32>"),
+            not(Self = "core::cell::Cell<u64>"),
+            not(Self = "core::cell::Cell<usize>"),
+            not(Self = "core::cell::Cell<i8>"),
+            not(Self = "core::cell::Cell<i16>"),
+            not(Self = "core::cell::Cell<i32>"),
+            not(Self = "core::cell::Cell<i64>"),
+            not(Self = "core::cell::Cell<isize>"),
+            not(Self = "core::cell::Cell<bool>")
         ),
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock`",
     ),
     on(
-        _Self = "core::cell::RefCell<T>",
+        Self = "core::cell::RefCell<T>",
         note = "if you want to do aliasing and mutation between multiple threads, use `std::sync::RwLock` instead",
     ),
     message = "`{Self}` cannot be shared between threads safely",
diff --git a/library/core/src/ops/arith.rs b/library/core/src/ops/arith.rs
index 54d79beca95..098ce4531f0 100644
--- a/library/core/src/ops/arith.rs
+++ b/library/core/src/ops/arith.rs
@@ -67,8 +67,8 @@
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_const_unstable(feature = "const_ops", issue = "90080")]
 #[rustc_on_unimplemented(
-    on(all(_Self = "{integer}", Rhs = "{float}"), message = "cannot add a float to an integer",),
-    on(all(_Self = "{float}", Rhs = "{integer}"), message = "cannot add an integer to a float",),
+    on(all(Self = "{integer}", Rhs = "{float}"), message = "cannot add a float to an integer",),
+    on(all(Self = "{float}", Rhs = "{integer}"), message = "cannot add an integer to a float",),
     message = "cannot add `{Rhs}` to `{Self}`",
     label = "no implementation for `{Self} + {Rhs}`",
     append_const_msg
diff --git a/library/core/src/ops/function.rs b/library/core/src/ops/function.rs
index e9014458b48..df48c104410 100644
--- a/library/core/src/ops/function.rs
+++ b/library/core/src/ops/function.rs
@@ -62,7 +62,7 @@ use crate::marker::Tuple;
         note = "wrap the `{Self}` in a closure with no arguments: `|| {{ /* code */ }}`"
     ),
     on(
-        _Self = "unsafe fn",
+        Self = "unsafe fn",
         note = "unsafe function cannot be called generically without an unsafe block",
         // SAFETY: tidy is not smart enough to tell that the below unsafe block is a string
         label = "call the function in a closure: `|| unsafe {{ /* code */ }}`"
@@ -149,7 +149,7 @@ pub trait Fn<Args: Tuple>: FnMut<Args> {
         note = "wrap the `{Self}` in a closure with no arguments: `|| {{ /* code */ }}`"
     ),
     on(
-        _Self = "unsafe fn",
+        Self = "unsafe fn",
         note = "unsafe function cannot be called generically without an unsafe block",
         // SAFETY: tidy is not smart enough to tell that the below unsafe block is a string
         label = "call the function in a closure: `|| unsafe {{ /* code */ }}`"
@@ -228,7 +228,7 @@ pub trait FnMut<Args: Tuple>: FnOnce<Args> {
         note = "wrap the `{Self}` in a closure with no arguments: `|| {{ /* code */ }}`"
     ),
     on(
-        _Self = "unsafe fn",
+        Self = "unsafe fn",
         note = "unsafe function cannot be called generically without an unsafe block",
         // SAFETY: tidy is not smart enough to tell that the below unsafe block is a string
         label = "call the function in a closure: `|| unsafe {{ /* code */ }}`"
diff --git a/library/core/src/ops/index.rs b/library/core/src/ops/index.rs
index 46e19bed43a..8092fa9eb2f 100644
--- a/library/core/src/ops/index.rs
+++ b/library/core/src/ops/index.rs
@@ -144,17 +144,17 @@ pub trait Index<Idx: ?Sized> {
 #[lang = "index_mut"]
 #[rustc_on_unimplemented(
     on(
-        _Self = "&str",
+        Self = "&str",
         note = "you can use `.chars().nth()` or `.bytes().nth()`
 see chapter in The Book <https://doc.rust-lang.org/book/ch08-02-strings.html#indexing-into-strings>"
     ),
     on(
-        _Self = "str",
+        Self = "str",
         note = "you can use `.chars().nth()` or `.bytes().nth()`
 see chapter in The Book <https://doc.rust-lang.org/book/ch08-02-strings.html#indexing-into-strings>"
     ),
     on(
-        _Self = "alloc::string::String",
+        Self = "alloc::string::String",
         note = "you can use `.chars().nth()` or `.bytes().nth()`
 see chapter in The Book <https://doc.rust-lang.org/book/ch08-02-strings.html#indexing-into-strings>"
     ),
diff --git a/library/core/src/ops/try_trait.rs b/library/core/src/ops/try_trait.rs
index 3ba2957526f..bac8ffb074b 100644
--- a/library/core/src/ops/try_trait.rs
+++ b/library/core/src/ops/try_trait.rs
@@ -117,12 +117,12 @@ use crate::ops::ControlFlow;
     on(
         all(from_desugaring = "TryBlock"),
         message = "a `try` block must return `Result` or `Option` \
-                    (or another type that implements `{Try}`)",
+                    (or another type that implements `{This}`)",
         label = "could not wrap the final value of the block as `{Self}` doesn't implement `Try`",
     ),
     on(
         all(from_desugaring = "QuestionMark"),
-        message = "the `?` operator can only be applied to values that implement `{Try}`",
+        message = "the `?` operator can only be applied to values that implement `{This}`",
         label = "the `?` operator cannot be applied to type `{Self}`"
     )
 )]
@@ -226,7 +226,7 @@ pub trait Try: FromResidual {
     on(
         all(
             from_desugaring = "QuestionMark",
-            _Self = "core::result::Result<T, E>",
+            Self = "core::result::Result<T, E>",
             R = "core::option::Option<core::convert::Infallible>",
         ),
         message = "the `?` operator can only be used on `Result`s, not `Option`s, \
@@ -237,7 +237,7 @@ pub trait Try: FromResidual {
     on(
         all(
             from_desugaring = "QuestionMark",
-            _Self = "core::result::Result<T, E>",
+            Self = "core::result::Result<T, E>",
         ),
         // There's a special error message in the trait selection code for
         // `From` in `?`, so this is not shown for result-in-result errors,
@@ -250,7 +250,7 @@ pub trait Try: FromResidual {
     on(
         all(
             from_desugaring = "QuestionMark",
-            _Self = "core::option::Option<T>",
+            Self = "core::option::Option<T>",
             R = "core::result::Result<T, E>",
         ),
         message = "the `?` operator can only be used on `Option`s, not `Result`s, \
@@ -261,7 +261,7 @@ pub trait Try: FromResidual {
     on(
         all(
             from_desugaring = "QuestionMark",
-            _Self = "core::option::Option<T>",
+            Self = "core::option::Option<T>",
         ),
         // `Option`-in-`Option` always works, as there's only one possible
         // residual, so this can also be phrased strongly.
@@ -273,7 +273,7 @@ pub trait Try: FromResidual {
     on(
         all(
             from_desugaring = "QuestionMark",
-            _Self = "core::ops::control_flow::ControlFlow<B, C>",
+            Self = "core::ops::control_flow::ControlFlow<B, C>",
             R = "core::ops::control_flow::ControlFlow<B, C>",
         ),
         message = "the `?` operator in {ItemContext} that returns `ControlFlow<B, _>` \
@@ -285,7 +285,7 @@ pub trait Try: FromResidual {
     on(
         all(
             from_desugaring = "QuestionMark",
-            _Self = "core::ops::control_flow::ControlFlow<B, C>",
+            Self = "core::ops::control_flow::ControlFlow<B, C>",
             // `R` is not a `ControlFlow`, as that case was matched previously
         ),
         message = "the `?` operator can only be used on `ControlFlow`s \
@@ -297,7 +297,7 @@ pub trait Try: FromResidual {
         all(from_desugaring = "QuestionMark"),
         message = "the `?` operator can only be used in {ItemContext} \
                     that returns `Result` or `Option` \
-                    (or another type that implements `{FromResidual}`)",
+                    (or another type that implements `{This}`)",
         label = "cannot use the `?` operator in {ItemContext} that returns `{Self}`",
         parent_label = "this function should return `Result` or `Option` to accept `?`"
     ),
diff --git a/library/core/src/option.rs b/library/core/src/option.rs
index aed5a043c11..1d264b26076 100644
--- a/library/core/src/option.rs
+++ b/library/core/src/option.rs
@@ -120,20 +120,22 @@
 //!
 //! Rust guarantees to optimize the following types `T` such that
 //! [`Option<T>`] has the same size, alignment, and [function call ABI] as `T`. In some
-//! of these cases, Rust further guarantees that
-//! `transmute::<_, Option<T>>([0u8; size_of::<T>()])` is sound and
-//! produces `Option::<T>::None`. These cases are identified by the
-//! second column:
-//!
-//! | `T`                                                                 | `transmute::<_, Option<T>>([0u8; size_of::<T>()])` sound? |
-//! |---------------------------------------------------------------------|----------------------------------------------------------------------|
-//! | [`Box<U>`] (specifically, only `Box<U, Global>`)                    | when `U: Sized`                                                      |
-//! | `&U`                                                                | when `U: Sized`                                                      |
-//! | `&mut U`                                                            | when `U: Sized`                                                      |
-//! | `fn`, `extern "C" fn`[^extern_fn]                                   | always                                                               |
-//! | [`num::NonZero*`]                                                   | always                                                               |
-//! | [`ptr::NonNull<U>`]                                                 | when `U: Sized`                                                      |
-//! | `#[repr(transparent)]` struct around one of the types in this list. | when it holds for the inner type                                     |
+//! of these cases, Rust further guarantees the following:
+//! - `transmute::<_, Option<T>>([0u8; size_of::<T>()])` is sound and produces
+//!   `Option::<T>::None`
+//! - `transmute::<_, [u8; size_of::<T>()]>(Option::<T>::None)` is sound and produces
+//!   `[0u8; size_of::<T>()]`
+//! These cases are identified by the second column:
+//!
+//! | `T`                                                                 | Transmuting between `[0u8; size_of::<T>()]` and `Option::<T>::None` sound? |
+//! |---------------------------------------------------------------------|----------------------------------------------------------------------------|
+//! | [`Box<U>`] (specifically, only `Box<U, Global>`)                    | when `U: Sized`                                                            |
+//! | `&U`                                                                | when `U: Sized`                                                            |
+//! | `&mut U`                                                            | when `U: Sized`                                                            |
+//! | `fn`, `extern "C" fn`[^extern_fn]                                   | always                                                                     |
+//! | [`num::NonZero*`]                                                   | always                                                                     |
+//! | [`ptr::NonNull<U>`]                                                 | when `U: Sized`                                                            |
+//! | `#[repr(transparent)]` struct around one of the types in this list. | when it holds for the inner type                                           |
 //!
 //! [^extern_fn]: this remains true for any argument/return types and any other ABI: `extern "abi" fn` (_e.g._, `extern "system" fn`)
 //!
diff --git a/library/core/src/ptr/const_ptr.rs b/library/core/src/ptr/const_ptr.rs
index f6109cafe86..19ed7599a51 100644
--- a/library/core/src/ptr/const_ptr.rs
+++ b/library/core/src/ptr/const_ptr.rs
@@ -76,15 +76,13 @@ impl<T: ?Sized> *const T {
     /// ```rust
     /// #![feature(pointer_try_cast_aligned)]
     ///
-    /// let aligned: *const u8 = 0x1000 as _;
+    /// let x = 0u64;
     ///
-    /// // i32 has at most 4-byte alignment, so this will succeed
-    /// assert!(aligned.try_cast_aligned::<i32>().is_some());
+    /// let aligned: *const u64 = &x;
+    /// let unaligned = unsafe { aligned.byte_add(1) };
     ///
-    /// let unaligned: *const u8 = 0x1001 as _;
-    ///
-    /// // i32 has at least 2-byte alignment, so this will fail
-    /// assert!(unaligned.try_cast_aligned::<i32>().is_none());
+    /// assert!(aligned.try_cast_aligned::<u32>().is_some());
+    /// assert!(unaligned.try_cast_aligned::<u32>().is_none());
     /// ```
     #[unstable(feature = "pointer_try_cast_aligned", issue = "141221")]
     #[must_use = "this returns the result of the operation, \
diff --git a/library/core/src/ptr/mut_ptr.rs b/library/core/src/ptr/mut_ptr.rs
index 2662a4fdc31..53aa3ab4938 100644
--- a/library/core/src/ptr/mut_ptr.rs
+++ b/library/core/src/ptr/mut_ptr.rs
@@ -58,15 +58,13 @@ impl<T: ?Sized> *mut T {
     /// ```rust
     /// #![feature(pointer_try_cast_aligned)]
     ///
-    /// let aligned: *mut u8 = 0x1000 as _;
+    /// let mut x = 0u64;
     ///
-    /// // i32 has at most 4-byte alignment, so this will succeed
-    /// assert!(aligned.try_cast_aligned::<i32>().is_some());
+    /// let aligned: *mut u64 = &mut x;
+    /// let unaligned = unsafe { aligned.byte_add(1) };
     ///
-    /// let unaligned: *mut u8 = 0x1001 as _;
-    ///
-    /// // i32 has at least 2-byte alignment, so this will fail
-    /// assert!(unaligned.try_cast_aligned::<i32>().is_none());
+    /// assert!(aligned.try_cast_aligned::<u32>().is_some());
+    /// assert!(unaligned.try_cast_aligned::<u32>().is_none());
     /// ```
     #[unstable(feature = "pointer_try_cast_aligned", issue = "141221")]
     #[must_use = "this returns the result of the operation, \
diff --git a/library/core/src/ptr/non_null.rs b/library/core/src/ptr/non_null.rs
index bb344c6a0d3..7c9b898f8e9 100644
--- a/library/core/src/ptr/non_null.rs
+++ b/library/core/src/ptr/non_null.rs
@@ -501,15 +501,13 @@ impl<T: ?Sized> NonNull<T> {
     /// #![feature(pointer_try_cast_aligned)]
     /// use std::ptr::NonNull;
     ///
-    /// let aligned: NonNull<u8> = NonNull::new(0x1000 as _).unwrap();
+    /// let mut x = 0u64;
     ///
-    /// // i32 has at most 4-byte alignment, so this will succeed
-    /// assert!(aligned.try_cast_aligned::<i32>().is_some());
+    /// let aligned = NonNull::from_mut(&mut x);
+    /// let unaligned = unsafe { aligned.byte_add(1) };
     ///
-    /// let unaligned: NonNull<u8> = NonNull::new(0x1001 as _).unwrap();
-    ///
-    /// // i32 has at least 2-byte alignment, so this will fail
-    /// assert!(unaligned.try_cast_aligned::<i32>().is_none());
+    /// assert!(aligned.try_cast_aligned::<u32>().is_some());
+    /// assert!(unaligned.try_cast_aligned::<u32>().is_none());
     /// ```
     #[unstable(feature = "pointer_try_cast_aligned", issue = "141221")]
     #[must_use = "this returns the result of the operation, \
diff --git a/library/core/src/slice/index.rs b/library/core/src/slice/index.rs
index aafa19c0dd3..409bad9f061 100644
--- a/library/core/src/slice/index.rs
+++ b/library/core/src/slice/index.rs
@@ -161,7 +161,7 @@ mod private_slice_index {
 #[rustc_on_unimplemented(
     on(T = "str", label = "string indices are ranges of `usize`",),
     on(
-        all(any(T = "str", T = "&str", T = "alloc::string::String"), _Self = "{integer}"),
+        all(any(T = "str", T = "&str", T = "alloc::string::String"), Self = "{integer}"),
         note = "you can use `.chars().nth()` or `.bytes().nth()`\n\
                 for more information, see chapter 8 in The Book: \
                 <https://doc.rust-lang.org/book/ch08-02-strings.html#indexing-into-strings>"
diff --git a/library/core/src/sync/atomic.rs b/library/core/src/sync/atomic.rs
index 84c7f1aafe1..bd5a58d74ba 100644
--- a/library/core/src/sync/atomic.rs
+++ b/library/core/src/sync/atomic.rs
@@ -193,7 +193,7 @@
 //!
 //! A simple spinlock:
 //!
-//! ```
+//! ```ignore-wasm
 //! use std::sync::Arc;
 //! use std::sync::atomic::{AtomicUsize, Ordering};
 //! use std::{hint, thread};
@@ -622,7 +622,7 @@ impl AtomicBool {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```ignore-wasm
     /// #![feature(atomic_from_mut)]
     /// use std::sync::atomic::{AtomicBool, Ordering};
     ///
@@ -653,7 +653,7 @@ impl AtomicBool {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```rust,ignore-wasm
     /// #![feature(atomic_from_mut)]
     /// use std::sync::atomic::{AtomicBool, Ordering};
     ///
@@ -1548,7 +1548,7 @@ impl<T> AtomicPtr<T> {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```ignore-wasm
     /// #![feature(atomic_from_mut)]
     /// use std::ptr::null_mut;
     /// use std::sync::atomic::{AtomicPtr, Ordering};
@@ -1585,7 +1585,7 @@ impl<T> AtomicPtr<T> {
     ///
     /// # Examples
     ///
-    /// ```
+    /// ```ignore-wasm
     /// #![feature(atomic_from_mut)]
     /// use std::ptr::null_mut;
     /// use std::sync::atomic::{AtomicPtr, Ordering};
@@ -2692,7 +2692,7 @@ macro_rules! atomic_int {
             ///
             /// # Examples
             ///
-            /// ```
+            /// ```ignore-wasm
             /// #![feature(atomic_from_mut)]
             #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")]
             ///
@@ -2725,7 +2725,7 @@ macro_rules! atomic_int {
             ///
             /// # Examples
             ///
-            /// ```
+            /// ```ignore-wasm
             /// #![feature(atomic_from_mut)]
             #[doc = concat!($extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};")]
             ///
diff --git a/library/std/src/io/pipe.rs b/library/std/src/io/pipe.rs
index 47243806cd2..16727d44541 100644
--- a/library/std/src/io/pipe.rs
+++ b/library/std/src/io/pipe.rs
@@ -38,30 +38,44 @@ use crate::sys_common::{FromInner, IntoInner};
 /// > not rely on a particular capacity: an application should be designed so that a reading process
 /// > consumes data as soon as it is available, so that a writing process does not remain blocked.
 ///
-/// # Examples
+/// # Example
 ///
 /// ```no_run
 /// # #[cfg(miri)] fn main() {}
 /// # #[cfg(not(miri))]
 /// # fn main() -> std::io::Result<()> {
+/// use std::io::{Read, Write, pipe};
 /// use std::process::Command;
-/// use std::io::{pipe, Read, Write};
-/// let (ping_rx, mut ping_tx) = pipe()?;
-/// let (mut pong_rx, pong_tx) = pipe()?;
+/// let (ping_reader, mut ping_writer) = pipe()?;
+/// let (mut pong_reader, pong_writer) = pipe()?;
 ///
-/// // Spawn a process that echoes its input.
-/// let mut echo_server = Command::new("cat").stdin(ping_rx).stdout(pong_tx).spawn()?;
+/// // Spawn a child process that echoes its input.
+/// let mut echo_command = Command::new("cat");
+/// echo_command.stdin(ping_reader);
+/// echo_command.stdout(pong_writer);
+/// let mut echo_child = echo_command.spawn()?;
 ///
-/// ping_tx.write_all(b"hello")?;
-/// // Close to unblock echo_server's reader.
-/// drop(ping_tx);
+/// // Send input to the child process. Note that because we're writing all the input before we
+/// // read any output, this could deadlock if the child's input and output pipe buffers both
+/// // filled up. Those buffers are usually at least a few KB, so "hello" is fine, but for longer
+/// // inputs we'd need to read and write at the same time, e.g. using threads.
+/// ping_writer.write_all(b"hello")?;
+///
+/// // `cat` exits when it reads EOF from stdin, but that can't happen while any ping writer
+/// // remains open. We need to drop our ping writer, or read_to_string will deadlock below.
+/// drop(ping_writer);
+///
+/// // The pong reader can't report EOF while any pong writer remains open. Our Command object is
+/// // holding a pong writer, and again read_to_string will deadlock if we don't drop it.
+/// drop(echo_command);
 ///
 /// let mut buf = String::new();
-/// // Block until echo_server's writer is closed.
-/// pong_rx.read_to_string(&mut buf)?;
+/// // Block until `cat` closes its stdout (a pong writer).
+/// pong_reader.read_to_string(&mut buf)?;
 /// assert_eq!(&buf, "hello");
 ///
-/// echo_server.wait()?;
+/// // At this point we know `cat` has exited, but we still need to wait to clean up the "zombie".
+/// echo_child.wait()?;
 /// # Ok(())
 /// # }
 /// ```
diff --git a/library/std/src/os/net/linux_ext/addr.rs b/library/std/src/os/net/linux_ext/addr.rs
index aed772056e1..41009c0e284 100644
--- a/library/std/src/os/net/linux_ext/addr.rs
+++ b/library/std/src/os/net/linux_ext/addr.rs
@@ -23,7 +23,10 @@ pub trait SocketAddrExt: Sealed {
     ///
     /// ```no_run
     /// use std::os::unix::net::{UnixListener, SocketAddr};
+    /// #[cfg(target_os = "linux")]
     /// use std::os::linux::net::SocketAddrExt;
+    /// #[cfg(target_os = "android")]
+    /// use std::os::android::net::SocketAddrExt;
     ///
     /// fn main() -> std::io::Result<()> {
     ///     let addr = SocketAddr::from_abstract_name(b"hidden")?;
@@ -48,7 +51,10 @@ pub trait SocketAddrExt: Sealed {
     ///
     /// ```no_run
     /// use std::os::unix::net::{UnixListener, SocketAddr};
+    /// #[cfg(target_os = "linux")]
     /// use std::os::linux::net::SocketAddrExt;
+    /// #[cfg(target_os = "android")]
+    /// use std::os::android::net::SocketAddrExt;
     ///
     /// fn main() -> std::io::Result<()> {
     ///     let name = b"hidden";
diff --git a/library/std/src/os/net/linux_ext/socket.rs b/library/std/src/os/net/linux_ext/socket.rs
index 4e4168f693c..a15feb6bd9f 100644
--- a/library/std/src/os/net/linux_ext/socket.rs
+++ b/library/std/src/os/net/linux_ext/socket.rs
@@ -27,7 +27,10 @@ pub trait UnixSocketExt: Sealed {
     ///
     /// ```no_run
     /// #![feature(unix_socket_ancillary_data)]
+    /// #[cfg(target_os = "linux")]
     /// use std::os::linux::net::UnixSocketExt;
+    /// #[cfg(target_os = "android")]
+    /// use std::os::android::net::UnixSocketExt;
     /// use std::os::unix::net::UnixDatagram;
     ///
     /// fn main() -> std::io::Result<()> {
diff --git a/library/std/src/os/net/linux_ext/tcp.rs b/library/std/src/os/net/linux_ext/tcp.rs
index c8d012962d4..95dffb3bc43 100644
--- a/library/std/src/os/net/linux_ext/tcp.rs
+++ b/library/std/src/os/net/linux_ext/tcp.rs
@@ -25,7 +25,10 @@ pub trait TcpStreamExt: Sealed {
     /// ```no_run
     /// #![feature(tcp_quickack)]
     /// use std::net::TcpStream;
+    /// #[cfg(target_os = "linux")]
     /// use std::os::linux::net::TcpStreamExt;
+    /// #[cfg(target_os = "android")]
+    /// use std::os::android::net::TcpStreamExt;
     ///
     /// let stream = TcpStream::connect("127.0.0.1:8080")
     ///         .expect("Couldn't connect to the server...");
@@ -43,7 +46,10 @@ pub trait TcpStreamExt: Sealed {
     /// ```no_run
     /// #![feature(tcp_quickack)]
     /// use std::net::TcpStream;
+    /// #[cfg(target_os = "linux")]
     /// use std::os::linux::net::TcpStreamExt;
+    /// #[cfg(target_os = "android")]
+    /// use std::os::android::net::TcpStreamExt;
     ///
     /// let stream = TcpStream::connect("127.0.0.1:8080")
     ///         .expect("Couldn't connect to the server...");
diff --git a/library/std/src/panic.rs b/library/std/src/panic.rs
index f3b26ac64df..234fb284a59 100644
--- a/library/std/src/panic.rs
+++ b/library/std/src/panic.rs
@@ -356,7 +356,7 @@ pub use core::panic::abort_unwind;
 /// ```
 #[stable(feature = "catch_unwind", since = "1.9.0")]
 pub fn catch_unwind<F: FnOnce() -> R + UnwindSafe, R>(f: F) -> Result<R> {
-    unsafe { panicking::r#try(f) }
+    unsafe { panicking::catch_unwind(f) }
 }
 
 /// Triggers a panic without invoking the panic hook.
diff --git a/library/std/src/panicking.rs b/library/std/src/panicking.rs
index 4bfedf78366..7873049d20b 100644
--- a/library/std/src/panicking.rs
+++ b/library/std/src/panicking.rs
@@ -499,13 +499,13 @@ pub use realstd::rt::panic_count;
 
 /// Invoke a closure, capturing the cause of an unwinding panic if one occurs.
 #[cfg(feature = "panic_immediate_abort")]
-pub unsafe fn r#try<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>> {
+pub unsafe fn catch_unwind<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>> {
     Ok(f())
 }
 
 /// Invoke a closure, capturing the cause of an unwinding panic if one occurs.
 #[cfg(not(feature = "panic_immediate_abort"))]
-pub unsafe fn r#try<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>> {
+pub unsafe fn catch_unwind<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>> {
     union Data<F, R> {
         f: ManuallyDrop<F>,
         r: ManuallyDrop<R>,
@@ -541,7 +541,7 @@ pub unsafe fn r#try<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>>
     let data_ptr = (&raw mut data) as *mut u8;
     // SAFETY:
     //
-    // Access to the union's fields: this is `std` and we know that the `r#try`
+    // Access to the union's fields: this is `std` and we know that the `catch_unwind`
     // intrinsic fills in the `r` or `p` union field based on its return value.
     //
     // The call to `intrinsics::catch_unwind` is made safe by:
@@ -602,7 +602,7 @@ pub unsafe fn r#try<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>>
     // This function cannot be marked as `unsafe` because `intrinsics::catch_unwind`
     // expects normal function pointers.
     #[inline]
-    #[rustc_nounwind] // `intrinsic::r#try` requires catch fn to be nounwind
+    #[rustc_nounwind] // `intrinsic::catch_unwind` requires catch fn to be nounwind
     fn do_catch<F: FnOnce() -> R, R>(data: *mut u8, payload: *mut u8) {
         // SAFETY: this is the responsibility of the caller, see above.
         //
diff --git a/library/std/src/process.rs b/library/std/src/process.rs
index df6b9a6e563..373584d0117 100644
--- a/library/std/src/process.rs
+++ b/library/std/src/process.rs
@@ -1348,7 +1348,7 @@ impl Output {
     ///
     /// ```
     /// #![feature(exit_status_error)]
-    /// # #[cfg(unix)] {
+    /// # #[cfg(all(unix, not(target_os = "android")))] {
     /// use std::process::Command;
     /// assert!(Command::new("false").output().unwrap().exit_ok().is_err());
     /// # }
@@ -1695,7 +1695,7 @@ impl From<io::Stdout> for Stdio {
     /// # Ok(())
     /// # }
     /// #
-    /// # if cfg!(unix) {
+    /// # if cfg!(all(unix, not(target_os = "android"))) {
     /// #     test().unwrap();
     /// # }
     /// ```
@@ -1724,7 +1724,7 @@ impl From<io::Stderr> for Stdio {
     /// # Ok(())
     /// # }
     /// #
-    /// # if cfg!(unix) {
+    /// # if cfg!(all(unix, not(target_os = "android"))) {
     /// #     test().unwrap();
     /// # }
     /// ```
@@ -1907,7 +1907,7 @@ impl crate::sealed::Sealed for ExitStatusError {}
 ///
 /// ```
 /// #![feature(exit_status_error)]
-/// # if cfg!(unix) {
+/// # if cfg!(all(unix, not(target_os = "android"))) {
 /// use std::process::{Command, ExitStatusError};
 ///
 /// fn run(cmd: &str) -> Result<(), ExitStatusError> {
@@ -1950,7 +1950,7 @@ impl ExitStatusError {
     ///
     /// ```
     /// #![feature(exit_status_error)]
-    /// # #[cfg(unix)] {
+    /// # #[cfg(all(unix, not(target_os = "android")))] {
     /// use std::process::Command;
     ///
     /// let bad = Command::new("false").status().unwrap().exit_ok().unwrap_err();
@@ -1975,7 +1975,7 @@ impl ExitStatusError {
     /// ```
     /// #![feature(exit_status_error)]
     ///
-    /// # if cfg!(unix) {
+    /// # if cfg!(all(unix, not(target_os = "android"))) {
     /// use std::num::NonZero;
     /// use std::process::Command;
     ///
@@ -2532,7 +2532,7 @@ pub fn id() -> u32 {
 #[rustc_on_unimplemented(on(
     cause = "MainFunctionType",
     message = "`main` has invalid return type `{Self}`",
-    label = "`main` can only return types that implement `{Termination}`"
+    label = "`main` can only return types that implement `{This}`"
 ))]
 pub trait Termination {
     /// Is called to get the representation of the value as status code.
diff --git a/library/std/src/sync/mpmc/list.rs b/library/std/src/sync/mpmc/list.rs
index 3fcfb85cf2a..050f26b097a 100644
--- a/library/std/src/sync/mpmc/list.rs
+++ b/library/std/src/sync/mpmc/list.rs
@@ -575,7 +575,7 @@ impl<T> Channel<T> {
         // After this point `head.block` is not modified again and it will be deallocated if it's
         // non-null. The `Drop` code of the channel, which runs after this function, also attempts
         // to deallocate `head.block` if it's non-null. Therefore this function must maintain the
-        // invariant that if a deallocation of head.block is attemped then it must also be set to
+        // invariant that if a deallocation of head.block is attempted then it must also be set to
         // NULL. Failing to do so will lead to the Drop code attempting a double free. For this
         // reason both reads above do an atomic swap instead of a simple atomic load.
 
diff --git a/library/std/src/sys/net/connection/uefi/mod.rs b/library/std/src/sys/net/connection/uefi/mod.rs
index da217439626..46d67c8e510 100644
--- a/library/std/src/sys/net/connection/uefi/mod.rs
+++ b/library/std/src/sys/net/connection/uefi/mod.rs
@@ -4,11 +4,14 @@ use crate::net::{Ipv4Addr, Ipv6Addr, Shutdown, SocketAddr};
 use crate::sys::unsupported;
 use crate::time::Duration;
 
-pub struct TcpStream(!);
+mod tcp;
+pub(crate) mod tcp4;
+
+pub struct TcpStream(#[expect(dead_code)] tcp::Tcp);
 
 impl TcpStream {
-    pub fn connect(_: io::Result<&SocketAddr>) -> io::Result<TcpStream> {
-        unsupported()
+    pub fn connect(addr: io::Result<&SocketAddr>) -> io::Result<TcpStream> {
+        tcp::Tcp::connect(addr?).map(Self)
     }
 
     pub fn connect_timeout(_: &SocketAddr, _: Duration) -> io::Result<TcpStream> {
@@ -16,105 +19,105 @@ impl TcpStream {
     }
 
     pub fn set_read_timeout(&self, _: Option<Duration>) -> io::Result<()> {
-        self.0
+        unsupported()
     }
 
     pub fn set_write_timeout(&self, _: Option<Duration>) -> io::Result<()> {
-        self.0
+        unsupported()
     }
 
     pub fn read_timeout(&self) -> io::Result<Option<Duration>> {
-        self.0
+        unsupported()
     }
 
     pub fn write_timeout(&self) -> io::Result<Option<Duration>> {
-        self.0
+        unsupported()
     }
 
     pub fn peek(&self, _: &mut [u8]) -> io::Result<usize> {
-        self.0
+        unsupported()
     }
 
     pub fn read(&self, _: &mut [u8]) -> io::Result<usize> {
-        self.0
+        unsupported()
     }
 
     pub fn read_buf(&self, _buf: BorrowedCursor<'_>) -> io::Result<()> {
-        self.0
+        unsupported()
     }
 
     pub fn read_vectored(&self, _: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
-        self.0
+        unsupported()
     }
 
     pub fn is_read_vectored(&self) -> bool {
-        self.0
+        false
     }
 
     pub fn write(&self, _: &[u8]) -> io::Result<usize> {
-        self.0
+        unsupported()
     }
 
     pub fn write_vectored(&self, _: &[IoSlice<'_>]) -> io::Result<usize> {
-        self.0
+        unsupported()
     }
 
     pub fn is_write_vectored(&self) -> bool {
-        self.0
+        false
     }
 
     pub fn peer_addr(&self) -> io::Result<SocketAddr> {
-        self.0
+        unsupported()
     }
 
     pub fn socket_addr(&self) -> io::Result<SocketAddr> {
-        self.0
+        unsupported()
     }
 
     pub fn shutdown(&self, _: Shutdown) -> io::Result<()> {
-        self.0
+        unsupported()
     }
 
     pub fn duplicate(&self) -> io::Result<TcpStream> {
-        self.0
+        unsupported()
     }
 
     pub fn set_linger(&self, _: Option<Duration>) -> io::Result<()> {
-        self.0
+        unsupported()
     }
 
     pub fn linger(&self) -> io::Result<Option<Duration>> {
-        self.0
+        unsupported()
     }
 
     pub fn set_nodelay(&self, _: bool) -> io::Result<()> {
-        self.0
+        unsupported()
     }
 
     pub fn nodelay(&self) -> io::Result<bool> {
-        self.0
+        unsupported()
     }
 
     pub fn set_ttl(&self, _: u32) -> io::Result<()> {
-        self.0
+        unsupported()
     }
 
     pub fn ttl(&self) -> io::Result<u32> {
-        self.0
+        unsupported()
     }
 
     pub fn take_error(&self) -> io::Result<Option<io::Error>> {
-        self.0
+        unsupported()
     }
 
     pub fn set_nonblocking(&self, _: bool) -> io::Result<()> {
-        self.0
+        unsupported()
     }
 }
 
 impl fmt::Debug for TcpStream {
     fn fmt(&self, _f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        self.0
+        todo!()
     }
 }
 
diff --git a/library/std/src/sys/net/connection/uefi/tcp.rs b/library/std/src/sys/net/connection/uefi/tcp.rs
new file mode 100644
index 00000000000..f87accdc41d
--- /dev/null
+++ b/library/std/src/sys/net/connection/uefi/tcp.rs
@@ -0,0 +1,21 @@
+use super::tcp4;
+use crate::io;
+use crate::net::SocketAddr;
+
+pub(crate) enum Tcp {
+    V4(#[expect(dead_code)] tcp4::Tcp4),
+}
+
+impl Tcp {
+    pub(crate) fn connect(addr: &SocketAddr) -> io::Result<Self> {
+        match addr {
+            SocketAddr::V4(x) => {
+                let temp = tcp4::Tcp4::new()?;
+                temp.configure(true, Some(x), None)?;
+                temp.connect()?;
+                Ok(Tcp::V4(temp))
+            }
+            SocketAddr::V6(_) => todo!(),
+        }
+    }
+}
diff --git a/library/std/src/sys/net/connection/uefi/tcp4.rs b/library/std/src/sys/net/connection/uefi/tcp4.rs
new file mode 100644
index 00000000000..f7ca373b52b
--- /dev/null
+++ b/library/std/src/sys/net/connection/uefi/tcp4.rs
@@ -0,0 +1,118 @@
+use r_efi::efi::{self, Status};
+use r_efi::protocols::tcp4;
+
+use crate::io;
+use crate::net::SocketAddrV4;
+use crate::ptr::NonNull;
+use crate::sync::atomic::{AtomicBool, Ordering};
+use crate::sys::pal::helpers;
+
+const TYPE_OF_SERVICE: u8 = 8;
+const TIME_TO_LIVE: u8 = 255;
+
+pub(crate) struct Tcp4 {
+    protocol: NonNull<tcp4::Protocol>,
+    flag: AtomicBool,
+    #[expect(dead_code)]
+    service_binding: helpers::ServiceProtocol,
+}
+
+const DEFAULT_ADDR: efi::Ipv4Address = efi::Ipv4Address { addr: [0u8; 4] };
+
+impl Tcp4 {
+    pub(crate) fn new() -> io::Result<Self> {
+        let service_binding = helpers::ServiceProtocol::open(tcp4::SERVICE_BINDING_PROTOCOL_GUID)?;
+        let protocol = helpers::open_protocol(service_binding.child_handle(), tcp4::PROTOCOL_GUID)?;
+
+        Ok(Self { service_binding, protocol, flag: AtomicBool::new(false) })
+    }
+
+    pub(crate) fn configure(
+        &self,
+        active: bool,
+        remote_address: Option<&SocketAddrV4>,
+        station_address: Option<&SocketAddrV4>,
+    ) -> io::Result<()> {
+        let protocol = self.protocol.as_ptr();
+
+        let (remote_address, remote_port) = if let Some(x) = remote_address {
+            (helpers::ipv4_to_r_efi(*x.ip()), x.port())
+        } else {
+            (DEFAULT_ADDR, 0)
+        };
+
+        // FIXME: Remove when passive connections with proper subnet handling are added
+        assert!(station_address.is_none());
+        let use_default_address = efi::Boolean::TRUE;
+        let (station_address, station_port) = (DEFAULT_ADDR, 0);
+        let subnet_mask = helpers::ipv4_to_r_efi(crate::net::Ipv4Addr::new(0, 0, 0, 0));
+
+        let mut config_data = tcp4::ConfigData {
+            type_of_service: TYPE_OF_SERVICE,
+            time_to_live: TIME_TO_LIVE,
+            access_point: tcp4::AccessPoint {
+                use_default_address,
+                remote_address,
+                remote_port,
+                active_flag: active.into(),
+                station_address,
+                station_port,
+                subnet_mask,
+            },
+            control_option: crate::ptr::null_mut(),
+        };
+
+        let r = unsafe { ((*protocol).configure)(protocol, &mut config_data) };
+        if r.is_error() { Err(crate::io::Error::from_raw_os_error(r.as_usize())) } else { Ok(()) }
+    }
+
+    pub(crate) fn connect(&self) -> io::Result<()> {
+        let evt = unsafe { self.create_evt() }?;
+        let completion_token =
+            tcp4::CompletionToken { event: evt.as_ptr(), status: Status::SUCCESS };
+
+        let protocol = self.protocol.as_ptr();
+        let mut conn_token = tcp4::ConnectionToken { completion_token };
+
+        let r = unsafe { ((*protocol).connect)(protocol, &mut conn_token) };
+        if r.is_error() {
+            return Err(io::Error::from_raw_os_error(r.as_usize()));
+        }
+
+        self.wait_for_flag();
+
+        if completion_token.status.is_error() {
+            Err(io::Error::from_raw_os_error(completion_token.status.as_usize()))
+        } else {
+            Ok(())
+        }
+    }
+
+    unsafe fn create_evt(&self) -> io::Result<helpers::OwnedEvent> {
+        self.flag.store(false, Ordering::Relaxed);
+        helpers::OwnedEvent::new(
+            efi::EVT_NOTIFY_SIGNAL,
+            efi::TPL_CALLBACK,
+            Some(toggle_atomic_flag),
+            Some(unsafe { NonNull::new_unchecked(self.flag.as_ptr().cast()) }),
+        )
+    }
+
+    fn wait_for_flag(&self) {
+        while !self.flag.load(Ordering::Relaxed) {
+            let _ = self.poll();
+        }
+    }
+
+    fn poll(&self) -> io::Result<()> {
+        let protocol = self.protocol.as_ptr();
+        let r = unsafe { ((*protocol).poll)(protocol) };
+
+        if r.is_error() { Err(io::Error::from_raw_os_error(r.as_usize())) } else { Ok(()) }
+    }
+}
+
+extern "efiapi" fn toggle_atomic_flag(_: r_efi::efi::Event, ctx: *mut crate::ffi::c_void) {
+    let flag = unsafe { AtomicBool::from_ptr(ctx.cast()) };
+    flag.store(true, Ordering::Relaxed);
+}
diff --git a/library/std/src/sys/pal/uefi/helpers.rs b/library/std/src/sys/pal/uefi/helpers.rs
index 6ee3e0a8b66..e47263348db 100644
--- a/library/std/src/sys/pal/uefi/helpers.rs
+++ b/library/std/src/sys/pal/uefi/helpers.rs
@@ -653,7 +653,6 @@ pub(crate) struct ServiceProtocol {
 }
 
 impl ServiceProtocol {
-    #[expect(dead_code)]
     pub(crate) fn open(service_guid: r_efi::efi::Guid) -> io::Result<Self> {
         let handles = locate_handles(service_guid)?;
 
@@ -670,7 +669,6 @@ impl ServiceProtocol {
         Err(io::const_error!(io::ErrorKind::NotFound, "no service binding protocol found"))
     }
 
-    #[expect(dead_code)]
     pub(crate) fn child_handle(&self) -> NonNull<crate::ffi::c_void> {
         self.child_handle
     }
@@ -732,6 +730,10 @@ impl OwnedEvent {
         }
     }
 
+    pub(crate) fn as_ptr(&self) -> efi::Event {
+        self.0.as_ptr()
+    }
+
     pub(crate) fn into_raw(self) -> *mut crate::ffi::c_void {
         let r = self.0.as_ptr();
         crate::mem::forget(self);
@@ -755,3 +757,7 @@ impl Drop for OwnedEvent {
         }
     }
 }
+
+pub(crate) const fn ipv4_to_r_efi(addr: crate::net::Ipv4Addr) -> efi::Ipv4Address {
+    efi::Ipv4Address { addr: addr.octets() }
+}
diff --git a/library/std/src/sys/pal/windows/os.rs b/library/std/src/sys/pal/windows/os.rs
index 1ebbbec9e91..f331282d2d7 100644
--- a/library/std/src/sys/pal/windows/os.rs
+++ b/library/std/src/sys/pal/windows/os.rs
@@ -202,8 +202,6 @@ fn home_dir_crt() -> Option<PathBuf> {
             |buf, mut sz| {
                 // GetUserProfileDirectoryW does not quite use the usual protocol for
                 // negotiating the buffer size, so we have to translate.
-                // FIXME(#141254): We rely on the *undocumented* property that this function will
-                // always set the size, not just on failure.
                 match c::GetUserProfileDirectoryW(
                     ptr::without_provenance_mut(CURRENT_PROCESS_TOKEN),
                     buf,
diff --git a/library/std/src/sys/process/unix/common.rs b/library/std/src/sys/process/unix/common.rs
index e205a839005..b6777b76668 100644
--- a/library/std/src/sys/process/unix/common.rs
+++ b/library/std/src/sys/process/unix/common.rs
@@ -1,8 +1,10 @@
 #[cfg(all(test, not(target_os = "emscripten")))]
 mod tests;
 
-use libc::{EXIT_FAILURE, EXIT_SUCCESS, c_char, c_int, gid_t, pid_t, uid_t};
+use libc::{EXIT_FAILURE, EXIT_SUCCESS, c_int, gid_t, pid_t, uid_t};
 
+pub use self::cstring_array::CStringArray;
+use self::cstring_array::CStringIter;
 use crate::collections::BTreeMap;
 use crate::ffi::{CStr, CString, OsStr, OsString};
 use crate::os::unix::prelude::*;
@@ -14,7 +16,9 @@ use crate::sys::fs::OpenOptions;
 use crate::sys::pipe::{self, AnonPipe};
 use crate::sys::process::env::{CommandEnv, CommandEnvs};
 use crate::sys_common::{FromInner, IntoInner};
-use crate::{fmt, io, ptr};
+use crate::{fmt, io};
+
+mod cstring_array;
 
 cfg_if::cfg_if! {
     if #[cfg(target_os = "fuchsia")] {
@@ -77,13 +81,7 @@ cfg_if::cfg_if! {
 
 pub struct Command {
     program: CString,
-    args: Vec<CString>,
-    /// Exactly what will be passed to `execvp`.
-    ///
-    /// First element is a pointer to `program`, followed by pointers to
-    /// `args`, followed by a `null`. Be careful when modifying `program` or
-    /// `args` to properly update this as well.
-    argv: Argv,
+    args: CStringArray,
     env: CommandEnv,
 
     program_kind: ProgramKind,
@@ -102,14 +100,6 @@ pub struct Command {
     pgroup: Option<pid_t>,
 }
 
-// Create a new type for argv, so that we can make it `Send` and `Sync`
-struct Argv(Vec<*const c_char>);
-
-// It is safe to make `Argv` `Send` and `Sync`, because it contains
-// pointers to memory owned by `Command.args`
-unsafe impl Send for Argv {}
-unsafe impl Sync for Argv {}
-
 // passed back to std::process with the pipes connected to the child, if any
 // were requested
 pub struct StdioPipes {
@@ -171,42 +161,17 @@ impl ProgramKind {
 }
 
 impl Command {
-    #[cfg(not(target_os = "linux"))]
     pub fn new(program: &OsStr) -> Command {
         let mut saw_nul = false;
         let program_kind = ProgramKind::new(program.as_ref());
         let program = os2c(program, &mut saw_nul);
+        let mut args = CStringArray::with_capacity(1);
+        args.push(program.clone());
         Command {
-            argv: Argv(vec![program.as_ptr(), ptr::null()]),
-            args: vec![program.clone()],
             program,
-            program_kind,
+            args,
             env: Default::default(),
-            cwd: None,
-            chroot: None,
-            uid: None,
-            gid: None,
-            saw_nul,
-            closures: Vec::new(),
-            groups: None,
-            stdin: None,
-            stdout: None,
-            stderr: None,
-            pgroup: None,
-        }
-    }
-
-    #[cfg(target_os = "linux")]
-    pub fn new(program: &OsStr) -> Command {
-        let mut saw_nul = false;
-        let program_kind = ProgramKind::new(program.as_ref());
-        let program = os2c(program, &mut saw_nul);
-        Command {
-            argv: Argv(vec![program.as_ptr(), ptr::null()]),
-            args: vec![program.clone()],
-            program,
             program_kind,
-            env: Default::default(),
             cwd: None,
             chroot: None,
             uid: None,
@@ -217,6 +182,7 @@ impl Command {
             stdin: None,
             stdout: None,
             stderr: None,
+            #[cfg(target_os = "linux")]
             create_pidfd: false,
             pgroup: None,
         }
@@ -225,20 +191,11 @@ impl Command {
     pub fn set_arg_0(&mut self, arg: &OsStr) {
         // Set a new arg0
         let arg = os2c(arg, &mut self.saw_nul);
-        debug_assert!(self.argv.0.len() > 1);
-        self.argv.0[0] = arg.as_ptr();
-        self.args[0] = arg;
+        self.args.write(0, arg);
     }
 
     pub fn arg(&mut self, arg: &OsStr) {
-        // Overwrite the trailing null pointer in `argv` and then add a new null
-        // pointer.
         let arg = os2c(arg, &mut self.saw_nul);
-        self.argv.0[self.args.len()] = arg.as_ptr();
-        self.argv.0.push(ptr::null());
-
-        // Also make sure we keep track of the owned value to schedule a
-        // destructor for this memory.
         self.args.push(arg);
     }
 
@@ -295,6 +252,8 @@ impl Command {
 
     pub fn get_args(&self) -> CommandArgs<'_> {
         let mut iter = self.args.iter();
+        // argv[0] contains the program name, but we are only interested in the
+        // arguments so skip it.
         iter.next();
         CommandArgs { iter }
     }
@@ -307,12 +266,12 @@ impl Command {
         self.cwd.as_ref().map(|cs| Path::new(OsStr::from_bytes(cs.as_bytes())))
     }
 
-    pub fn get_argv(&self) -> &Vec<*const c_char> {
-        &self.argv.0
+    pub fn get_argv(&self) -> &CStringArray {
+        &self.args
     }
 
     pub fn get_program_cstr(&self) -> &CStr {
-        &*self.program
+        &self.program
     }
 
     #[allow(dead_code)]
@@ -405,32 +364,6 @@ fn os2c(s: &OsStr, saw_nul: &mut bool) -> CString {
     })
 }
 
-// Helper type to manage ownership of the strings within a C-style array.
-pub struct CStringArray {
-    items: Vec<CString>,
-    ptrs: Vec<*const c_char>,
-}
-
-impl CStringArray {
-    pub fn with_capacity(capacity: usize) -> Self {
-        let mut result = CStringArray {
-            items: Vec::with_capacity(capacity),
-            ptrs: Vec::with_capacity(capacity + 1),
-        };
-        result.ptrs.push(ptr::null());
-        result
-    }
-    pub fn push(&mut self, item: CString) {
-        let l = self.ptrs.len();
-        self.ptrs[l - 1] = item.as_ptr();
-        self.ptrs.push(ptr::null());
-        self.items.push(item);
-    }
-    pub fn as_ptr(&self) -> *const *const c_char {
-        self.ptrs.as_ptr()
-    }
-}
-
 fn construct_envp(env: BTreeMap<OsString, OsString>, saw_nul: &mut bool) -> CStringArray {
     let mut result = CStringArray::with_capacity(env.len());
     for (mut k, v) in env {
@@ -619,14 +552,16 @@ impl fmt::Debug for Command {
                     write!(f, "{}={value:?} ", key.to_string_lossy())?;
                 }
             }
-            if self.program != self.args[0] {
+
+            if *self.program != self.args[0] {
                 write!(f, "[{:?}] ", self.program)?;
             }
-            write!(f, "{:?}", self.args[0])?;
+            write!(f, "{:?}", &self.args[0])?;
 
-            for arg in &self.args[1..] {
+            for arg in self.get_args() {
                 write!(f, " {:?}", arg)?;
             }
+
             Ok(())
         }
     }
@@ -658,14 +593,16 @@ impl From<u8> for ExitCode {
 }
 
 pub struct CommandArgs<'a> {
-    iter: crate::slice::Iter<'a, CString>,
+    iter: CStringIter<'a>,
 }
 
 impl<'a> Iterator for CommandArgs<'a> {
     type Item = &'a OsStr;
+
     fn next(&mut self) -> Option<&'a OsStr> {
-        self.iter.next().map(|cs| OsStr::from_bytes(cs.as_bytes()))
+        self.iter.next().map(|cs| OsStr::from_bytes(cs.to_bytes()))
     }
+
     fn size_hint(&self) -> (usize, Option<usize>) {
         self.iter.size_hint()
     }
@@ -675,6 +612,7 @@ impl<'a> ExactSizeIterator for CommandArgs<'a> {
     fn len(&self) -> usize {
         self.iter.len()
     }
+
     fn is_empty(&self) -> bool {
         self.iter.is_empty()
     }
diff --git a/library/std/src/sys/process/unix/common/cstring_array.rs b/library/std/src/sys/process/unix/common/cstring_array.rs
new file mode 100644
index 00000000000..1c840a85df9
--- /dev/null
+++ b/library/std/src/sys/process/unix/common/cstring_array.rs
@@ -0,0 +1,115 @@
+use crate::ffi::{CStr, CString, c_char};
+use crate::ops::Index;
+use crate::{fmt, mem, ptr};
+
+/// Helper type to manage ownership of the strings within a C-style array.
+///
+/// This type manages an array of C-string pointers terminated by a null
+/// pointer. The pointer to the array (as returned by `as_ptr`) can be used as
+/// a value of `argv` or `environ`.
+pub struct CStringArray {
+    ptrs: Vec<*const c_char>,
+}
+
+impl CStringArray {
+    /// Creates a new `CStringArray` with enough capacity to hold `capacity`
+    /// strings.
+    pub fn with_capacity(capacity: usize) -> Self {
+        let mut result = CStringArray { ptrs: Vec::with_capacity(capacity + 1) };
+        result.ptrs.push(ptr::null());
+        result
+    }
+
+    /// Replace the string at position `index`.
+    pub fn write(&mut self, index: usize, item: CString) {
+        let argc = self.ptrs.len() - 1;
+        let ptr = &mut self.ptrs[..argc][index];
+        let old = mem::replace(ptr, item.into_raw());
+        // SAFETY:
+        // `CStringArray` owns all of its strings, and they were all transformed
+        // into pointers using `CString::into_raw`. Also, this is not the null
+        // pointer since the indexing above would have failed.
+        drop(unsafe { CString::from_raw(old.cast_mut()) });
+    }
+
+    /// Push an additional string to the array.
+    pub fn push(&mut self, item: CString) {
+        let argc = self.ptrs.len() - 1;
+        // Replace the null pointer at the end of the array...
+        self.ptrs[argc] = item.into_raw();
+        // ... and recreate it to restore the data structure invariant.
+        self.ptrs.push(ptr::null());
+    }
+
+    /// Returns a pointer to the C-string array managed by this type.
+    pub fn as_ptr(&self) -> *const *const c_char {
+        self.ptrs.as_ptr()
+    }
+
+    /// Returns an iterator over all `CStr`s contained in this array.
+    pub fn iter(&self) -> CStringIter<'_> {
+        CStringIter { iter: self.ptrs[..self.ptrs.len() - 1].iter() }
+    }
+}
+
+impl Index<usize> for CStringArray {
+    type Output = CStr;
+    fn index(&self, index: usize) -> &CStr {
+        let ptr = self.ptrs[..self.ptrs.len() - 1][index];
+        // SAFETY:
+        // `CStringArray` owns all of its strings. Also, this is not the null
+        // pointer since the indexing above would have failed.
+        unsafe { CStr::from_ptr(ptr) }
+    }
+}
+
+impl fmt::Debug for CStringArray {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_list().entries(self.iter()).finish()
+    }
+}
+
+// SAFETY: `CStringArray` is basically just a `Vec<CString>`
+unsafe impl Send for CStringArray {}
+// SAFETY: `CStringArray` is basically just a `Vec<CString>`
+unsafe impl Sync for CStringArray {}
+
+impl Drop for CStringArray {
+    fn drop(&mut self) {
+        // SAFETY:
+        // `CStringArray` owns all of its strings, and they were all transformed
+        // into pointers using `CString::into_raw`.
+        self.ptrs[..self.ptrs.len() - 1]
+            .iter()
+            .for_each(|&p| drop(unsafe { CString::from_raw(p.cast_mut()) }))
+    }
+}
+
+/// An iterator over all `CStr`s contained in a `CStringArray`.
+#[derive(Clone)]
+pub struct CStringIter<'a> {
+    iter: crate::slice::Iter<'a, *const c_char>,
+}
+
+impl<'a> Iterator for CStringIter<'a> {
+    type Item = &'a CStr;
+    fn next(&mut self) -> Option<&'a CStr> {
+        // SAFETY:
+        // `CStringArray` owns all of its strings. Also, this is not the null
+        // pointer since the last element is excluded when creating `iter`.
+        self.iter.next().map(|&p| unsafe { CStr::from_ptr(p) })
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.iter.size_hint()
+    }
+}
+
+impl<'a> ExactSizeIterator for CStringIter<'a> {
+    fn len(&self) -> usize {
+        self.iter.len()
+    }
+    fn is_empty(&self) -> bool {
+        self.iter.is_empty()
+    }
+}
diff --git a/library/std/src/sys/thread_local/guard/key.rs b/library/std/src/sys/thread_local/guard/key.rs
index 59581e6f281..f91471419c1 100644
--- a/library/std/src/sys/thread_local/guard/key.rs
+++ b/library/std/src/sys/thread_local/guard/key.rs
@@ -32,7 +32,7 @@ pub fn enable() {
 
 /// On platforms with key-based TLS, the system runs the destructors for us.
 /// We still have to make sure that [`crate::rt::thread_cleanup`] is called,
-/// however. This is done by defering the execution of a TLS destructor to
+/// however. This is done by deferring the execution of a TLS destructor to
 /// the next round of destruction inside the TLS destructors.
 #[cfg(not(target_thread_local))]
 pub fn enable() {
@@ -46,7 +46,7 @@ pub fn enable() {
     unsafe extern "C" fn run(state: *mut u8) {
         if state == DEFER {
             // Make sure that this function is run again in the next round of
-            // TLS destruction. If there is no futher round, there will be leaks,
+            // TLS destruction. If there is no further round, there will be leaks,
             // but that's okay, `thread_cleanup` is not guaranteed to be called.
             unsafe { set(CLEANUP.force(), RUN) }
         } else {
diff --git a/library/std/tests/path.rs b/library/std/tests/path.rs
index 978402b6fda..87e0d226cbd 100644
--- a/library/std/tests/path.rs
+++ b/library/std/tests/path.rs
@@ -1976,3 +1976,34 @@ fn clone_to_uninit() {
     unsafe { a.clone_to_uninit(ptr::from_mut::<Path>(&mut b).cast()) };
     assert_eq!(a, &*b);
 }
+
+// Test: Only separators (e.g., "/" or "\\")
+// This test checks how Path handles a string that consists only of path separators.
+// It should recognize the root and not treat it as a normal component.
+#[test]
+fn test_only_separators() {
+    let path = Path::new("/////");
+    assert!(path.has_root());
+    assert_eq!(path.iter().count(), 1);
+    assert_eq!(path.parent(), None);
+}
+
+// Test: Non-ASCII/Unicode
+// This test verifies that Path can handle Unicode and non-ASCII characters in the path.
+// It ensures that such paths are not rejected or misinterpreted.
+#[test]
+fn test_non_ascii_unicode() {
+    let path = Path::new("/tmp/❤/🚀/file.txt");
+    assert!(path.to_str().is_some());
+    assert_eq!(path.file_name(), Some(OsStr::new("file.txt")));
+}
+
+// Test: Embedded newlines
+// This test verifies that newlines within path components are preserved and do not break path parsing.
+// It ensures that Path treats newlines as normal characters.
+#[test]
+fn test_embedded_newline() {
+    let path = Path::new("foo\nbar");
+    assert_eq!(path.file_name(), Some(OsStr::new("foo\nbar")));
+    assert_eq!(path.to_str(), Some("foo\nbar"));
+}
diff --git a/src/bootstrap/src/core/build_steps/setup.rs b/src/bootstrap/src/core/build_steps/setup.rs
index 31ec462134d..5e22c2d1acb 100644
--- a/src/bootstrap/src/core/build_steps/setup.rs
+++ b/src/bootstrap/src/core/build_steps/setup.rs
@@ -585,11 +585,13 @@ Select which editor you would like to set up [default: None]: ";
                 "d29af4d949bbe2371eac928a3c31cf9496b1701aa1c45f11cd6c759865ad5c45",
                 "b5dd299b93dca3ceeb9b335f929293cb3d4bf4977866fbe7ceeac2a8a9f99088",
                 "631c837b0e98ae35fd48b0e5f743b1ca60adadf2d0a2b23566ba25df372cf1a9",
+                "080955765db84bb6cbf178879f489c4e2369397626a6ecb3debedb94a9d0b3ce",
             ],
             EditorKind::Helix => &[
                 "2d3069b8cf1b977e5d4023965eb6199597755e6c96c185ed5f2854f98b83d233",
                 "6736d61409fbebba0933afd2e4c44ff2f97c1cb36cf0299a7f4a7819b8775040",
                 "f252dcc30ca85a193a699581e5e929d5bd6c19d40d7a7ade5e257a9517a124a5",
+                "198c195ed0c070d15907b279b8b4ea96198ca71b939f5376454f3d636ab54da5",
             ],
             EditorKind::Vim | EditorKind::VsCode => &[
                 "ea67e259dedf60d4429b6c349a564ffcd1563cf41c920a856d1f5b16b4701ac8",
@@ -604,11 +606,13 @@ Select which editor you would like to set up [default: None]: ";
                 "c394386e6133bbf29ffd32c8af0bb3d4aac354cba9ee051f29612aa9350f8f8d",
                 "e53e9129ca5ee5dcbd6ec8b68c2d87376474eb154992deba3c6d9ab1703e0717",
                 "f954316090936c7e590c253ca9d524008375882fa13c5b41d7e2547a896ff893",
+                "701b73751efd7abd6487f2c79348dab698af7ac4427b79fa3d2087c867144b12",
             ],
             EditorKind::Zed => &[
                 "bbce727c269d1bd0c98afef4d612eb4ce27aea3c3a8968c5f10b31affbc40b6c",
                 "a5380cf5dd9328731aecc5dfb240d16dac46ed272126b9728006151ef42f5909",
                 "2e96bf0d443852b12f016c8fc9840ab3d0a2b4fe0b0fb3a157e8d74d5e7e0e26",
+                "4fadd4c87389a601a27db0d3d74a142fa3a2e656ae78982e934dbe24bee32ad6",
             ],
         }
     }
diff --git a/src/bootstrap/src/utils/shared_helpers.rs b/src/bootstrap/src/utils/shared_helpers.rs
index 08e1c21e58e..561af34a447 100644
--- a/src/bootstrap/src/utils/shared_helpers.rs
+++ b/src/bootstrap/src/utils/shared_helpers.rs
@@ -46,7 +46,16 @@ pub fn dylib_path() -> Vec<std::path::PathBuf> {
 /// Given an executable called `name`, return the filename for the
 /// executable for a particular target.
 pub fn exe(name: &str, target: &str) -> String {
-    if target.contains("windows") {
+    // On Cygwin, the decision to append .exe or not is not as straightforward.
+    // Executable files do actually have .exe extensions so on hosts other than
+    // Cygwin it is necessary.  But on a Cygwin host there is magic happening
+    // that redirects requests for file X to file X.exe if it exists, and
+    // furthermore /proc/self/exe (and thus std::env::current_exe) always
+    // returns the name *without* the .exe extension.  For comparisons against
+    // that to match, we therefore do not append .exe for Cygwin targets on
+    // a Cygwin host.
+    if target.contains("windows") || (cfg!(not(target_os = "cygwin")) && target.contains("cygwin"))
+    {
         format!("{name}.exe")
     } else if target.contains("uefi") {
         format!("{name}.efi")
diff --git a/src/ci/citool/Cargo.lock b/src/ci/citool/Cargo.lock
index 43321d12caf..571f18e7cf1 100644
--- a/src/ci/citool/Cargo.lock
+++ b/src/ci/citool/Cargo.lock
@@ -66,9 +66,9 @@ checksum = "34ac096ce696dc2fcabef30516bb13c0a68a11d30131d3df6f04711467681b04"
 
 [[package]]
 name = "askama"
-version = "0.13.1"
+version = "0.14.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5d4744ed2eef2645831b441d8f5459689ade2ab27c854488fbab1fbe94fce1a7"
+checksum = "f75363874b771be265f4ffe307ca705ef6f3baa19011c149da8674a87f1b75c4"
 dependencies = [
  "askama_derive",
  "itoa",
@@ -79,9 +79,9 @@ dependencies = [
 
 [[package]]
 name = "askama_derive"
-version = "0.13.1"
+version = "0.14.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d661e0f57be36a5c14c48f78d09011e67e0cb618f269cca9f2fd8d15b68c46ac"
+checksum = "129397200fe83088e8a68407a8e2b1f826cf0086b21ccdb866a722c8bcd3a94f"
 dependencies = [
  "askama_parser",
  "basic-toml",
@@ -96,9 +96,9 @@ dependencies = [
 
 [[package]]
 name = "askama_parser"
-version = "0.13.0"
+version = "0.14.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cf315ce6524c857bb129ff794935cf6d42c82a6cff60526fe2a63593de4d0d4f"
+checksum = "d6ab5630b3d5eaf232620167977f95eb51f3432fc76852328774afbd242d4358"
 dependencies = [
  "memchr",
  "serde",
diff --git a/src/ci/citool/Cargo.toml b/src/ci/citool/Cargo.toml
index 0e2aba3b9e3..f61243a4d71 100644
--- a/src/ci/citool/Cargo.toml
+++ b/src/ci/citool/Cargo.toml
@@ -5,7 +5,7 @@ edition = "2021"
 
 [dependencies]
 anyhow = "1"
-askama = "0.13"
+askama = "0.14"
 clap = { version = "4.5", features = ["derive"] }
 csv = "1"
 diff = "0.1"
diff --git a/src/ci/citool/src/jobs.rs b/src/ci/citool/src/jobs.rs
index 5600d7b4db5..60cbf50c7a3 100644
--- a/src/ci/citool/src/jobs.rs
+++ b/src/ci/citool/src/jobs.rs
@@ -85,14 +85,20 @@ impl JobDatabase {
 }
 
 pub fn load_job_db(db: &str) -> anyhow::Result<JobDatabase> {
-    let mut db: Value = serde_yaml::from_str(db)?;
+    let mut db: Value = serde_yaml::from_str(db).context("failed to parse YAML content")?;
 
     // We need to expand merge keys (<<), because serde_yaml can't deal with them
     // `apply_merge` only applies the merge once, so do it a few times to unwrap nested merges.
-    db.apply_merge()?;
-    db.apply_merge()?;
 
-    let db: JobDatabase = serde_yaml::from_value(db)?;
+    let apply_merge = |db: &mut Value| -> anyhow::Result<()> {
+        db.apply_merge().context("failed to apply merge keys")
+    };
+
+    // Apply merge twice to handle nested merges
+    apply_merge(&mut db)?;
+    apply_merge(&mut db)?;
+
+    let db: JobDatabase = serde_yaml::from_value(db).context("failed to parse job database")?;
     Ok(db)
 }
 
diff --git a/src/ci/docker/scripts/rfl-build.sh b/src/ci/docker/scripts/rfl-build.sh
index 1d280948ebe..fa18f67583f 100755
--- a/src/ci/docker/scripts/rfl-build.sh
+++ b/src/ci/docker/scripts/rfl-build.sh
@@ -2,7 +2,8 @@
 
 set -euo pipefail
 
-LINUX_VERSION=v6.15-rc4
+# https://github.com/Rust-for-Linux/linux/issues/1163
+LINUX_VERSION=3ca02fc80cc4fdac63aaa6796642f1e07be591d6
 
 # Build rustc, rustdoc, cargo, clippy-driver and rustfmt
 ../x.py build --stage 2 library rustdoc clippy rustfmt
diff --git a/src/ci/github-actions/jobs.yml b/src/ci/github-actions/jobs.yml
index 005007bbccd..2daa8624605 100644
--- a/src/ci/github-actions/jobs.yml
+++ b/src/ci/github-actions/jobs.yml
@@ -228,7 +228,7 @@ auto:
   - name: dist-x86_64-linux
     env:
       CODEGEN_BACKENDS: llvm,cranelift
-    <<: *job-linux-36c-codebuild
+    <<: *job-linux-16c
 
   - name: dist-x86_64-linux-alt
     env:
@@ -324,7 +324,7 @@ auto:
     <<: *job-linux-4c
 
   - name: x86_64-gnu-distcheck
-    <<: *job-linux-8c
+    <<: *job-linux-4c
 
   # The x86_64-gnu-llvm-20 job is split into multiple jobs to run tests in parallel.
   # x86_64-gnu-llvm-20-1 skips tests that run in x86_64-gnu-llvm-20-{2,3}.
diff --git a/src/doc/rustc/src/platform-support/solaris.md b/src/doc/rustc/src/platform-support/solaris.md
index 0452d76f6c2..c22b5c24c12 100644
--- a/src/doc/rustc/src/platform-support/solaris.md
+++ b/src/doc/rustc/src/platform-support/solaris.md
@@ -8,6 +8,7 @@ Rust for Solaris operating system.
 ## Target maintainers
 
 [@psumbera](https://github.com/psumbera)
+[@kulikjak](https://github.com/kulikjak)
 
 ## Requirements
 
diff --git a/src/doc/rustdoc/src/write-documentation/the-doc-attribute.md b/src/doc/rustdoc/src/write-documentation/the-doc-attribute.md
index 45146993371..6ec93d1746c 100644
--- a/src/doc/rustdoc/src/write-documentation/the-doc-attribute.md
+++ b/src/doc/rustdoc/src/write-documentation/the-doc-attribute.md
@@ -88,8 +88,10 @@ on your documentation examples make requests to.
 ```
 
 Now, when you press "run", the button will make a request to this domain. The request
-URL will contain 2 query parameters: `code` and `edition` for the code in the documentation
-and the Rust edition respectively.
+URL will contain 3 query parameters:
+1. `code` for the code in the documentation
+2. `version` for the Rust channel, e.g. nightly, which is decided by whether `code` contain unstable features
+3. `edition` for the Rust edition, e.g. 2024
 
 If you don't use this attribute, there will be no run buttons.
 
diff --git a/src/doc/unstable-book/src/compiler-flags/eagerly-emit-delayed-bugs.md b/src/doc/unstable-book/src/compiler-flags/eagerly-emit-delayed-bugs.md
new file mode 100644
index 00000000000..39f0c04a1b5
--- /dev/null
+++ b/src/doc/unstable-book/src/compiler-flags/eagerly-emit-delayed-bugs.md
@@ -0,0 +1,12 @@
+# `eagerly-emit-delayed-bugs`
+
+This feature is perma-unstable and has no tracking issue.
+
+------------------------
+
+This flag converts all [`span_delayed_bug()`] calls to [`bug!`] calls, exiting the compiler immediately and allowing you to generate a backtrace of where the delayed bug occurred.
+For full documentation, see [the rustc-dev-guide][dev-guide-delayed].
+
+[`bug!`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/macro.bug.html
+[`span_delayed_bug()`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_errors/struct.DiagCtxtHandle.html#method.span_delayed_bug
+[dev-guide-delayed]: https://rustc-dev-guide.rust-lang.org/compiler-debugging.html#debugging-delayed-bugs
diff --git a/src/doc/unstable-book/src/compiler-flags/track-diagnostics.md b/src/doc/unstable-book/src/compiler-flags/track-diagnostics.md
new file mode 100644
index 00000000000..48620214407
--- /dev/null
+++ b/src/doc/unstable-book/src/compiler-flags/track-diagnostics.md
@@ -0,0 +1,11 @@
+# `track-diagnostics`
+
+This feature is perma-unstable and has no tracking issue.
+
+------------------------
+
+This flag prints the source code span in the compiler where a diagnostic was generated, respecting [`#[track_caller]`][track_caller]. Note that this may be different from the place it was emitted.
+For full documentation, see [the rustc-dev-guide][dev-guide-track-diagnostics].
+
+[track_caller]: https://doc.rust-lang.org/reference/attributes/codegen.html#the-track_caller-attribute
+[dev-guide-track-diagnostics]: https://rustc-dev-guide.rust-lang.org/compiler-debugging.html#getting-the-error-creation-location
diff --git a/src/doc/unstable-book/src/compiler-flags/treat-err-as-bug.md b/src/doc/unstable-book/src/compiler-flags/treat-err-as-bug.md
new file mode 100644
index 00000000000..df7c380a50b
--- /dev/null
+++ b/src/doc/unstable-book/src/compiler-flags/treat-err-as-bug.md
@@ -0,0 +1,13 @@
+# `treat-err-as-bug`
+
+This feature is perma-unstable and has no tracking issue.
+
+------------------------
+
+This flag converts the selected error to a [`bug!`] call, exiting the compiler immediately and allowing you to generate a backtrace of where the error occurred.
+For full documentation, see [the rustc-dev-guide][dev-guide-backtrace].
+
+Note that the compiler automatically sets `RUST_BACKTRACE=1` for itself, and so you do not need to set it yourself when using this flag.
+
+[`bug!`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/macro.bug.html
+[dev-guide-backtrace]: https://rustc-dev-guide.rust-lang.org/compiler-debugging.html#getting-a-backtrace-for-errors
diff --git a/src/etc/rust_analyzer_eglot.el b/src/etc/rust_analyzer_eglot.el
index 90bd38aa894..3cb229cd98c 100644
--- a/src/etc/rust_analyzer_eglot.el
+++ b/src/etc/rust_analyzer_eglot.el
@@ -14,7 +14,7 @@
                                   "src/bootstrap/Cargo.toml"
                                   "src/tools/rust-analyzer/Cargo.toml"]
                  :rustfmt ( :overrideCommand ["build/host/rustfmt/bin/rustfmt"
-                                              "--edition=2021"])
+                                              "--edition=2024"])
                  :procMacro ( :server "build/host/stage0/libexec/rust-analyzer-proc-macro-srv"
                                       :enable t)
                  :cargo ( :buildScripts ( :enable t
diff --git a/src/etc/rust_analyzer_helix.toml b/src/etc/rust_analyzer_helix.toml
index 05fc7716a72..1a6a14991ec 100644
--- a/src/etc/rust_analyzer_helix.toml
+++ b/src/etc/rust_analyzer_helix.toml
@@ -32,7 +32,7 @@ overrideCommand = [
 [language-server.rust-analyzer.config.rustfmt]
 overrideCommand = [
     "build/rust-analyzer/host/rustfmt/bin/rustfmt",
-    "--edition=2021"
+    "--edition=2024"
 ]
 
 [language-server.rust-analyzer.config.procMacro]
diff --git a/src/etc/rust_analyzer_settings.json b/src/etc/rust_analyzer_settings.json
index 5ce886a9b65..a960cc01732 100644
--- a/src/etc/rust_analyzer_settings.json
+++ b/src/etc/rust_analyzer_settings.json
@@ -17,7 +17,7 @@
     ],
     "rust-analyzer.rustfmt.overrideCommand": [
         "${workspaceFolder}/build/host/rustfmt/bin/rustfmt",
-        "--edition=2021"
+        "--edition=2024"
     ],
     "rust-analyzer.procMacro.server": "${workspaceFolder}/build/host/stage0/libexec/rust-analyzer-proc-macro-srv",
     "rust-analyzer.procMacro.enable": true,
diff --git a/src/etc/rust_analyzer_zed.json b/src/etc/rust_analyzer_zed.json
index 3461ff887d9..27fc524e9b5 100644
--- a/src/etc/rust_analyzer_zed.json
+++ b/src/etc/rust_analyzer_zed.json
@@ -29,15 +29,15 @@
         ],
         "procMacro": {
           "enable": true,
-          "server": "${workspaceFolder}/build/host/stage0/libexec/rust-analyzer-proc-macro-srv"
+          "server": "build/host/stage0/libexec/rust-analyzer-proc-macro-srv"
         },
         "rustc": {
           "source": "./Cargo.toml"
         },
         "rustfmt": {
           "overrideCommand": [
-            "${workspaceFolder}/build/host/rustfmt/bin/rustfmt",
-            "--edition=2021"
+            "build/host/rustfmt/bin/rustfmt",
+            "--edition=2024"
           ]
         },
         "server": {
diff --git a/src/librustdoc/Cargo.toml b/src/librustdoc/Cargo.toml
index dbfdd8ebd16..bba8e630bcc 100644
--- a/src/librustdoc/Cargo.toml
+++ b/src/librustdoc/Cargo.toml
@@ -9,7 +9,7 @@ path = "lib.rs"
 
 [dependencies]
 arrayvec = { version = "0.7", default-features = false }
-askama = { version = "0.13", default-features = false, features = ["alloc", "config", "derive"] }
+askama = { version = "0.14", default-features = false, features = ["alloc", "config", "derive"] }
 base64 = "0.21.7"
 itertools = "0.12"
 indexmap = "2"
diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
index e45f28444fe..07ecd98f775 100644
--- a/src/librustdoc/clean/types.rs
+++ b/src/librustdoc/clean/types.rs
@@ -774,20 +774,11 @@ impl Item {
             .filter_map(|attr| {
                 if is_json {
                     match attr {
-                        hir::Attribute::Parsed(AttributeKind::Deprecation { .. }) => {
-                            // rustdoc-json stores this in `Item::deprecation`, so we
-                            // don't want it it `Item::attrs`.
-                            None
-                        }
-                        rustc_hir::Attribute::Parsed(
-                            rustc_attr_data_structures::AttributeKind::Repr(..),
-                        ) => {
-                            // We have separate pretty-printing logic for `#[repr(..)]` attributes.
-                            // For example, there are circumstances where `#[repr(transparent)]`
-                            // is applied but should not be publicly shown in rustdoc
-                            // because it isn't public API.
-                            None
-                        }
+                        // rustdoc-json stores this in `Item::deprecation`, so we
+                        // don't want it it `Item::attrs`.
+                        hir::Attribute::Parsed(AttributeKind::Deprecation { .. }) => None,
+                        // We have separate pretty-printing logic for `#[repr(..)]` attributes.
+                        hir::Attribute::Parsed(AttributeKind::Repr(..)) => None,
                         _ => Some({
                             let mut s = rustc_hir_pretty::attribute_to_string(&tcx, attr);
                             assert_eq!(s.pop(), Some('\n'));
@@ -820,7 +811,8 @@ impl Item {
             if repr.transparent() {
                 // Render `repr(transparent)` iff the non-1-ZST field is public or at least one
                 // field is public in case all fields are 1-ZST fields.
-                let render_transparent = cache.document_private
+                let render_transparent = is_json
+                    || cache.document_private
                     || adt
                         .all_fields()
                         .find(|field| {
diff --git a/src/librustdoc/clean/utils.rs b/src/librustdoc/clean/utils.rs
index af7986d030e..2e38b6cdc65 100644
--- a/src/librustdoc/clean/utils.rs
+++ b/src/librustdoc/clean/utils.rs
@@ -1,7 +1,7 @@
 use std::assert_matches::debug_assert_matches;
 use std::fmt::{self, Display, Write as _};
-use std::mem;
 use std::sync::LazyLock as Lazy;
+use std::{ascii, mem};
 
 use rustc_ast::tokenstream::TokenTree;
 use rustc_hir::def::{DefKind, Res};
@@ -24,7 +24,7 @@ use crate::clean::{
     clean_middle_ty, inline,
 };
 use crate::core::DocContext;
-use crate::display::Joined as _;
+use crate::display::{Joined as _, MaybeDisplay as _};
 
 #[cfg(test)]
 mod tests;
@@ -254,14 +254,7 @@ pub(crate) fn qpath_to_string(p: &hir::QPath<'_>) -> String {
     fmt::from_fn(|f| {
         segments
             .iter()
-            .map(|seg| {
-                fmt::from_fn(|f| {
-                    if seg.ident.name != kw::PathRoot {
-                        write!(f, "{}", seg.ident)?;
-                    }
-                    Ok(())
-                })
-            })
+            .map(|seg| (seg.ident.name != kw::PathRoot).then_some(seg.ident).maybe_display())
             .joined("::", f)
     })
     .to_string()
@@ -391,30 +384,12 @@ pub(crate) fn print_evaluated_const(
     })
 }
 
-fn format_integer_with_underscore_sep(num: &str) -> String {
-    let num_chars: Vec<_> = num.chars().collect();
-    let mut num_start_index = if num_chars.first() == Some(&'-') { 1 } else { 0 };
-    let chunk_size = match &num.as_bytes()[num_start_index..] {
-        [b'0', b'b' | b'x', ..] => {
-            num_start_index += 2;
-            4
-        }
-        [b'0', b'o', ..] => {
-            num_start_index += 2;
-            let remaining_chars = num_chars.len() - num_start_index;
-            if remaining_chars <= 6 {
-                // don't add underscores to Unix permissions like 0755 or 100755
-                return num.to_string();
-            }
-            3
-        }
-        _ => 3,
-    };
-
-    num_chars[..num_start_index]
-        .iter()
-        .chain(num_chars[num_start_index..].rchunks(chunk_size).rev().intersperse(&['_']).flatten())
-        .collect()
+fn format_integer_with_underscore_sep(num: u128, is_negative: bool) -> String {
+    let num = num.to_string();
+    let chars = num.as_ascii().unwrap();
+    let mut result = if is_negative { "-".to_string() } else { String::new() };
+    result.extend(chars.rchunks(3).rev().intersperse(&[ascii::Char::LowLine]).flatten());
+    result
 }
 
 fn print_const_with_custom_print_scalar<'tcx>(
@@ -428,7 +403,10 @@ fn print_const_with_custom_print_scalar<'tcx>(
     match (ct, ct.ty().kind()) {
         (mir::Const::Val(mir::ConstValue::Scalar(int), _), ty::Uint(ui)) => {
             let mut output = if with_underscores {
-                format_integer_with_underscore_sep(&int.to_string())
+                format_integer_with_underscore_sep(
+                    int.assert_scalar_int().to_bits_unchecked(),
+                    false,
+                )
             } else {
                 int.to_string()
             };
@@ -445,7 +423,10 @@ fn print_const_with_custom_print_scalar<'tcx>(
                 .size;
             let sign_extended_data = int.assert_scalar_int().to_int(size);
             let mut output = if with_underscores {
-                format_integer_with_underscore_sep(&sign_extended_data.to_string())
+                format_integer_with_underscore_sep(
+                    sign_extended_data.unsigned_abs(),
+                    sign_extended_data.is_negative(),
+                )
             } else {
                 sign_extended_data.to_string()
             };
diff --git a/src/librustdoc/clean/utils/tests.rs b/src/librustdoc/clean/utils/tests.rs
index ebf4b495483..65c8255b2f2 100644
--- a/src/librustdoc/clean/utils/tests.rs
+++ b/src/librustdoc/clean/utils/tests.rs
@@ -2,40 +2,10 @@ use super::*;
 
 #[test]
 fn int_format_decimal() {
-    assert_eq!(format_integer_with_underscore_sep("12345678"), "12_345_678");
-    assert_eq!(format_integer_with_underscore_sep("123"), "123");
-    assert_eq!(format_integer_with_underscore_sep("123459"), "123_459");
-    assert_eq!(format_integer_with_underscore_sep("-12345678"), "-12_345_678");
-    assert_eq!(format_integer_with_underscore_sep("-123"), "-123");
-    assert_eq!(format_integer_with_underscore_sep("-123459"), "-123_459");
-}
-
-#[test]
-fn int_format_hex() {
-    assert_eq!(format_integer_with_underscore_sep("0xab3"), "0xab3");
-    assert_eq!(format_integer_with_underscore_sep("0xa2345b"), "0xa2_345b");
-    assert_eq!(format_integer_with_underscore_sep("0xa2e6345b"), "0xa2e6_345b");
-    assert_eq!(format_integer_with_underscore_sep("-0xab3"), "-0xab3");
-    assert_eq!(format_integer_with_underscore_sep("-0xa2345b"), "-0xa2_345b");
-    assert_eq!(format_integer_with_underscore_sep("-0xa2e6345b"), "-0xa2e6_345b");
-}
-
-#[test]
-fn int_format_binary() {
-    assert_eq!(format_integer_with_underscore_sep("0o12345671"), "0o12_345_671");
-    assert_eq!(format_integer_with_underscore_sep("0o123"), "0o123");
-    assert_eq!(format_integer_with_underscore_sep("0o123451"), "0o123451");
-    assert_eq!(format_integer_with_underscore_sep("-0o12345671"), "-0o12_345_671");
-    assert_eq!(format_integer_with_underscore_sep("-0o123"), "-0o123");
-    assert_eq!(format_integer_with_underscore_sep("-0o123451"), "-0o123451");
-}
-
-#[test]
-fn int_format_octal() {
-    assert_eq!(format_integer_with_underscore_sep("0b101"), "0b101");
-    assert_eq!(format_integer_with_underscore_sep("0b101101011"), "0b1_0110_1011");
-    assert_eq!(format_integer_with_underscore_sep("0b01101011"), "0b0110_1011");
-    assert_eq!(format_integer_with_underscore_sep("-0b101"), "-0b101");
-    assert_eq!(format_integer_with_underscore_sep("-0b101101011"), "-0b1_0110_1011");
-    assert_eq!(format_integer_with_underscore_sep("-0b01101011"), "-0b0110_1011");
+    assert_eq!(format_integer_with_underscore_sep(12345678, false), "12_345_678");
+    assert_eq!(format_integer_with_underscore_sep(123, false), "123");
+    assert_eq!(format_integer_with_underscore_sep(123459, false), "123_459");
+    assert_eq!(format_integer_with_underscore_sep(12345678, true), "-12_345_678");
+    assert_eq!(format_integer_with_underscore_sep(123, true), "-123");
+    assert_eq!(format_integer_with_underscore_sep(123459, true), "-123_459");
 }
diff --git a/src/librustdoc/html/render/sidebar.rs b/src/librustdoc/html/render/sidebar.rs
index a9029972d96..361966325fb 100644
--- a/src/librustdoc/html/render/sidebar.rs
+++ b/src/librustdoc/html/render/sidebar.rs
@@ -127,7 +127,7 @@ pub(crate) mod filters {
     use askama::filters::Safe;
 
     use crate::html::escape::EscapeBodyTextWithWbr;
-    pub(crate) fn wrapped<T>(v: T) -> askama::Result<Safe<impl Display>>
+    pub(crate) fn wrapped<T, V: askama::Values>(v: T, _: V) -> askama::Result<Safe<impl Display>>
     where
         T: Display,
     {
diff --git a/src/librustdoc/html/render/write_shared.rs b/src/librustdoc/html/render/write_shared.rs
index b2bbf4614bf..4f6e9abdbca 100644
--- a/src/librustdoc/html/render/write_shared.rs
+++ b/src/librustdoc/html/render/write_shared.rs
@@ -611,7 +611,7 @@ impl TypeAliasPart {
                 .impl_
                 .values()
                 .flat_map(|AliasedTypeImpl { impl_, type_aliases }| {
-                    let mut ret = Vec::new();
+                    let mut ret: Vec<AliasSerializableImpl> = Vec::new();
                     let trait_ = impl_
                         .inner_impl()
                         .trait_
@@ -623,42 +623,43 @@ impl TypeAliasPart {
                     for &(type_alias_fqp, type_alias_item) in type_aliases {
                         cx.id_map.borrow_mut().clear();
                         cx.deref_id_map.borrow_mut().clear();
-                        let target_did = impl_
-                            .inner_impl()
-                            .trait_
-                            .as_ref()
-                            .map(|trait_| trait_.def_id())
-                            .or_else(|| impl_.inner_impl().for_.def_id(&cx.shared.cache));
-                        let provided_methods;
-                        let assoc_link = if let Some(target_did) = target_did {
-                            provided_methods = impl_.inner_impl().provided_trait_methods(cx.tcx());
-                            AssocItemLink::GotoSource(ItemId::DefId(target_did), &provided_methods)
-                        } else {
-                            AssocItemLink::Anchor(None)
-                        };
-                        let text = super::render_impl(
-                            cx,
-                            impl_,
-                            type_alias_item,
-                            assoc_link,
-                            RenderMode::Normal,
-                            None,
-                            &[],
-                            ImplRenderingParameters {
-                                show_def_docs: true,
-                                show_default_items: true,
-                                show_non_assoc_items: true,
-                                toggle_open_by_default: true,
-                            },
-                        )
-                        .to_string();
                         let type_alias_fqp = (*type_alias_fqp).iter().join("::");
-                        if Some(&text) == ret.last().map(|s: &AliasSerializableImpl| &s.text) {
-                            ret.last_mut()
-                                .expect("already established that ret.last() is Some()")
-                                .aliases
-                                .push(type_alias_fqp);
+                        if let Some(last) = ret.last_mut() {
+                            last.aliases.push(type_alias_fqp);
                         } else {
+                            let target_did = impl_
+                                .inner_impl()
+                                .trait_
+                                .as_ref()
+                                .map(|trait_| trait_.def_id())
+                                .or_else(|| impl_.inner_impl().for_.def_id(&cx.shared.cache));
+                            let provided_methods;
+                            let assoc_link = if let Some(target_did) = target_did {
+                                provided_methods =
+                                    impl_.inner_impl().provided_trait_methods(cx.tcx());
+                                AssocItemLink::GotoSource(
+                                    ItemId::DefId(target_did),
+                                    &provided_methods,
+                                )
+                            } else {
+                                AssocItemLink::Anchor(None)
+                            };
+                            let text = super::render_impl(
+                                cx,
+                                impl_,
+                                type_alias_item,
+                                assoc_link,
+                                RenderMode::Normal,
+                                None,
+                                &[],
+                                ImplRenderingParameters {
+                                    show_def_docs: true,
+                                    show_default_items: true,
+                                    show_non_assoc_items: true,
+                                    toggle_open_by_default: true,
+                                },
+                            )
+                            .to_string();
                             ret.push(AliasSerializableImpl {
                                 text,
                                 trait_: trait_.clone(),
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index 001668c54a7..025c135aff2 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -3,6 +3,8 @@
     html_playground_url = "https://play.rust-lang.org/"
 )]
 #![feature(rustc_private)]
+#![feature(ascii_char)]
+#![feature(ascii_char_variants)]
 #![feature(assert_matches)]
 #![feature(box_patterns)]
 #![feature(debug_closure_helpers)]
diff --git a/src/librustdoc/passes/collect_intra_doc_links.rs b/src/librustdoc/passes/collect_intra_doc_links.rs
index f3e2138d1a5..37628f16600 100644
--- a/src/librustdoc/passes/collect_intra_doc_links.rs
+++ b/src/librustdoc/passes/collect_intra_doc_links.rs
@@ -59,12 +59,7 @@ fn filter_assoc_items_by_name_and_namespace(
     ident: Ident,
     ns: Namespace,
 ) -> impl Iterator<Item = &ty::AssocItem> {
-    let iter: Box<dyn Iterator<Item = &ty::AssocItem>> = if !ident.name.is_empty() {
-        Box::new(tcx.associated_items(assoc_items_of).filter_by_name_unhygienic(ident.name))
-    } else {
-        Box::new([].iter())
-    };
-    iter.filter(move |item| {
+    tcx.associated_items(assoc_items_of).filter_by_name_unhygienic(ident.name).filter(move |item| {
         item.namespace() == ns && tcx.hygienic_eq(ident, item.ident(tcx), assoc_items_of)
     })
 }
diff --git a/src/librustdoc/passes/lint/bare_urls.rs b/src/librustdoc/passes/lint/bare_urls.rs
index 1e07277d38e..3b3ce3e9220 100644
--- a/src/librustdoc/passes/lint/bare_urls.rs
+++ b/src/librustdoc/passes/lint/bare_urls.rs
@@ -18,12 +18,15 @@ use crate::html::markdown::main_body_opts;
 
 pub(super) fn visit_item(cx: &DocContext<'_>, item: &Item, hir_id: HirId, dox: &str) {
     let report_diag = |cx: &DocContext<'_>, msg: &'static str, range: Range<usize>| {
-        let sp = source_span_for_markdown_range(cx.tcx, dox, &range, &item.attrs.doc_strings)
-            .unwrap_or_else(|| item.attr_span(cx.tcx));
+        let maybe_sp = source_span_for_markdown_range(cx.tcx, dox, &range, &item.attrs.doc_strings);
+        let sp = maybe_sp.unwrap_or_else(|| item.attr_span(cx.tcx));
         cx.tcx.node_span_lint(crate::lint::BARE_URLS, hir_id, sp, |lint| {
             lint.primary_message(msg)
-                .note("bare URLs are not automatically turned into clickable links")
-                .multipart_suggestion(
+                .note("bare URLs are not automatically turned into clickable links");
+            // The fallback of using the attribute span is suitable for
+            // highlighting where the error is, but not for placing the < and >
+            if let Some(sp) = maybe_sp {
+                lint.multipart_suggestion(
                     "use an automatic link instead",
                     vec![
                         (sp.shrink_to_lo(), "<".to_string()),
@@ -31,6 +34,7 @@ pub(super) fn visit_item(cx: &DocContext<'_>, item: &Item, hir_id: HirId, dox: &
                     ],
                     Applicability::MachineApplicable,
                 );
+            }
         });
     };
 
diff --git a/src/rustdoc-json-types/lib.rs b/src/rustdoc-json-types/lib.rs
index 0b8a9065294..c091c955ed5 100644
--- a/src/rustdoc-json-types/lib.rs
+++ b/src/rustdoc-json-types/lib.rs
@@ -30,7 +30,7 @@ pub type FxHashMap<K, V> = HashMap<K, V>; // re-export for use in src/librustdoc
 /// This integer is incremented with every breaking change to the API,
 /// and is returned along with the JSON blob as [`Crate::format_version`].
 /// Consuming code should assert that this value matches the format version(s) that it supports.
-pub const FORMAT_VERSION: u32 = 45;
+pub const FORMAT_VERSION: u32 = 46;
 
 /// The root of the emitted JSON blob.
 ///
diff --git a/src/tools/cargo b/src/tools/cargo
-Subproject 47c911e9e6f6461f90ce19142031fe16876a3b9
+Subproject 68db37499f2de8acef704c73d9031be6fbcbaee
diff --git a/src/tools/clippy/clippy_lints/src/manual_string_new.rs b/src/tools/clippy/clippy_lints/src/manual_string_new.rs
index 7ca3b712066..73ee1c3c78a 100644
--- a/src/tools/clippy/clippy_lints/src/manual_string_new.rs
+++ b/src/tools/clippy/clippy_lints/src/manual_string_new.rs
@@ -5,7 +5,7 @@ use rustc_hir::{Expr, ExprKind, PathSegment, QPath, TyKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty;
 use rustc_session::declare_lint_pass;
-use rustc_span::{Span, sym, symbol};
+use rustc_span::{Span, sym};
 
 declare_clippy_lint! {
     /// ### What it does
@@ -67,7 +67,7 @@ impl LateLintPass<'_> for ManualStringNew {
 fn is_expr_kind_empty_str(expr_kind: &ExprKind<'_>) -> bool {
     if let ExprKind::Lit(lit) = expr_kind
         && let LitKind::Str(value, _) = lit.node
-        && value == symbol::kw::Empty
+        && value == sym::empty
     {
         return true;
     }
diff --git a/src/tools/clippy/clippy_lints/src/methods/or_fun_call.rs b/src/tools/clippy/clippy_lints/src/methods/or_fun_call.rs
index c74c42e9e5b..38cb4d51ca0 100644
--- a/src/tools/clippy/clippy_lints/src/methods/or_fun_call.rs
+++ b/src/tools/clippy/clippy_lints/src/methods/or_fun_call.rs
@@ -12,7 +12,7 @@ use rustc_errors::Applicability;
 use rustc_lint::LateContext;
 use rustc_middle::ty;
 use rustc_span::Span;
-use rustc_span::symbol::{self, Symbol};
+use rustc_span::Symbol;
 use {rustc_ast as ast, rustc_hir as hir};
 
 use super::{OR_FUN_CALL, UNWRAP_OR_DEFAULT};
@@ -265,7 +265,7 @@ fn closure_body_returns_empty_to_string(cx: &LateContext<'_>, e: &hir::Expr<'_>)
             && ident.name == sym::to_string
             && let hir::Expr { kind, .. } = self_arg
             && let hir::ExprKind::Lit(lit) = kind
-            && let ast::LitKind::Str(symbol::kw::Empty, _) = lit.node
+            && let ast::LitKind::Str(rustc_span::sym::empty, _) = lit.node
         {
             return true;
         }
diff --git a/src/tools/clippy/tests/ui/duplicated_attributes.rs b/src/tools/clippy/tests/ui/duplicated_attributes.rs
index 874f5d22075..3ca91d6f182 100644
--- a/src/tools/clippy/tests/ui/duplicated_attributes.rs
+++ b/src/tools/clippy/tests/ui/duplicated_attributes.rs
@@ -21,7 +21,7 @@ fn foo() {}
 fn bar() {}
 
 // No warning:
-#[rustc_on_unimplemented(on(_Self = "&str", label = "`a"), on(_Self = "alloc::string::String", label = "a"))]
+#[rustc_on_unimplemented(on(Self = "&str", label = "`a"), on(Self = "alloc::string::String", label = "a"))]
 trait Abc {}
 
 #[proc_macro_attr::duplicated_attr()] // Should not warn!
diff --git a/src/tools/generate-copyright/Cargo.toml b/src/tools/generate-copyright/Cargo.toml
index ab76d0fc01e..e420a450d42 100644
--- a/src/tools/generate-copyright/Cargo.toml
+++ b/src/tools/generate-copyright/Cargo.toml
@@ -8,7 +8,7 @@ description = "Produces a manifest of all the copyrighted materials in the Rust
 
 [dependencies]
 anyhow = "1.0.65"
-askama = "0.13.0"
+askama = "0.14.0"
 cargo_metadata = "0.18.1"
 serde = { version = "1.0.147", features = ["derive"] }
 serde_json = "1.0.85"
diff --git a/src/tools/miri/src/bin/miri.rs b/src/tools/miri/src/bin/miri.rs
index 469fc264970..7098ef5130d 100644
--- a/src/tools/miri/src/bin/miri.rs
+++ b/src/tools/miri/src/bin/miri.rs
@@ -281,7 +281,7 @@ impl rustc_driver::Callbacks for MiriBeRustCompilerCalls {
                             }
                             let codegen_fn_attrs = tcx.codegen_fn_attrs(local_def_id);
                             if codegen_fn_attrs.contains_extern_indicator()
-                                || codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::USED)
+                                || codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::USED_COMPILER)
                                 || codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER)
                             {
                                 Some((
diff --git a/src/tools/miri/src/helpers.rs b/src/tools/miri/src/helpers.rs
index ff2ec1b3e60..6a6adc966a8 100644
--- a/src/tools/miri/src/helpers.rs
+++ b/src/tools/miri/src/helpers.rs
@@ -135,7 +135,7 @@ pub fn iter_exported_symbols<'tcx>(
             let codegen_attrs = tcx.codegen_fn_attrs(def_id);
             codegen_attrs.contains_extern_indicator()
                 || codegen_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL)
-                || codegen_attrs.flags.contains(CodegenFnAttrFlags::USED)
+                || codegen_attrs.flags.contains(CodegenFnAttrFlags::USED_COMPILER)
                 || codegen_attrs.flags.contains(CodegenFnAttrFlags::USED_LINKER)
         };
         if exported {
diff --git a/src/tools/miri/src/shims/panic.rs b/src/tools/miri/src/shims/panic.rs
index b5ed5ea837b..549d859a6e1 100644
--- a/src/tools/miri/src/shims/panic.rs
+++ b/src/tools/miri/src/shims/panic.rs
@@ -56,7 +56,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         interp_ok(())
     }
 
-    /// Handles the `try` intrinsic, the underlying implementation of `std::panicking::try`.
+    /// Handles the `catch_unwind` intrinsic.
     fn handle_catch_unwind(
         &mut self,
         args: &[OpTy<'tcx>],
@@ -66,7 +66,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         let this = self.eval_context_mut();
 
         // Signature:
-        //   fn r#try(try_fn: fn(*mut u8), data: *mut u8, catch_fn: fn(*mut u8, *mut u8)) -> i32
+        //   fn catch_unwind(try_fn: fn(*mut u8), data: *mut u8, catch_fn: fn(*mut u8, *mut u8)) -> i32
         // Calls `try_fn` with `data` as argument. If that executes normally, returns 0.
         // If that unwinds, calls `catch_fn` with the first argument being `data` and
         // then second argument being a target-dependent `payload` (i.e. it is up to us to define
@@ -120,14 +120,14 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         // We only care about `catch_panic` if we're unwinding - if we're doing a normal
         // return, then we don't need to do anything special.
         if let (true, Some(catch_unwind)) = (unwinding, extra.catch_unwind.take()) {
-            // We've just popped a frame that was pushed by `try`,
+            // We've just popped a frame that was pushed by `catch_unwind`,
             // and we are unwinding, so we should catch that.
             trace!(
                 "unwinding: found catch_panic frame during unwinding: {:?}",
                 this.frame().instance()
             );
 
-            // We set the return value of `try` to 1, since there was a panic.
+            // We set the return value of `catch_unwind` to 1, since there was a panic.
             this.write_scalar(Scalar::from_i32(1), &catch_unwind.dest)?;
 
             // The Thread's `panic_payload` holds what was passed to `miri_start_unwind`.
@@ -142,7 +142,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 ExternAbi::Rust,
                 &[catch_unwind.data, payload],
                 None,
-                // Directly return to caller of `try`.
+                // Directly return to caller of `catch_unwind`.
                 StackPopCleanup::Goto {
                     ret: catch_unwind.ret,
                     // `catch_fn` must not unwind.
diff --git a/src/tools/miri/src/shims/windows/env.rs b/src/tools/miri/src/shims/windows/env.rs
index 0cbabc52d2a..a7c26d601e5 100644
--- a/src/tools/miri/src/shims/windows/env.rs
+++ b/src/tools/miri/src/shims/windows/env.rs
@@ -230,7 +230,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         interp_ok(match directories::UserDirs::new() {
             Some(dirs) => {
                 let home = dirs.home_dir();
-                let size_avail = if this.ptr_is_null(size.ptr())? {
+                let size_avail = if this.ptr_is_null(buf)? {
                     0 // if the buf pointer is null, we can't write to it; `size` will be updated to the required length
                 } else {
                     this.read_scalar(&size)?.to_u32()?
@@ -238,8 +238,8 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 // Of course we cannot use `windows_check_buffer_size` here since this uses
                 // a different method for dealing with a too-small buffer than the other functions...
                 let (success, len) = this.write_path_to_wide_str(home, buf, size_avail.into())?;
-                // The Windows docs just say that this is written on failure, but std relies on it
-                // always being written. Also see <https://github.com/rust-lang/rust/issues/141254>.
+                // As per <https://github.com/MicrosoftDocs/sdk-api/pull/1810>, the size is always
+                // written, not just on failure.
                 this.write_scalar(Scalar::from_u32(len.try_into().unwrap()), &size)?;
                 if success {
                     Scalar::from_i32(1) // return TRUE
diff --git a/src/tools/miri/tests/fail/panic/bad_unwind.stderr b/src/tools/miri/tests/fail/panic/bad_unwind.stderr
index 6ba39e8f7e2..8c269eae62a 100644
--- a/src/tools/miri/tests/fail/panic/bad_unwind.stderr
+++ b/src/tools/miri/tests/fail/panic/bad_unwind.stderr
@@ -13,8 +13,8 @@ LL |     std::panic::catch_unwind(|| unwind()).unwrap_err();
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
    = note: BACKTRACE:
    = note: inside closure at tests/fail/panic/bad_unwind.rs:LL:CC
-   = note: inside `std::panicking::r#try::do_call::<{closure@tests/fail/panic/bad_unwind.rs:LL:CC}, ()>` at RUSTLIB/std/src/panicking.rs:LL:CC
-   = note: inside `std::panicking::r#try::<(), {closure@tests/fail/panic/bad_unwind.rs:LL:CC}>` at RUSTLIB/std/src/panicking.rs:LL:CC
+   = note: inside `std::panicking::catch_unwind::do_call::<{closure@tests/fail/panic/bad_unwind.rs:LL:CC}, ()>` at RUSTLIB/std/src/panicking.rs:LL:CC
+   = note: inside `std::panicking::catch_unwind::<(), {closure@tests/fail/panic/bad_unwind.rs:LL:CC}>` at RUSTLIB/std/src/panicking.rs:LL:CC
    = note: inside `std::panic::catch_unwind::<{closure@tests/fail/panic/bad_unwind.rs:LL:CC}, ()>` at RUSTLIB/std/src/panic.rs:LL:CC
 note: inside `main`
   --> tests/fail/panic/bad_unwind.rs:LL:CC
diff --git a/src/tools/miri/tests/fail/tail_calls/cc-mismatch.stderr b/src/tools/miri/tests/fail/tail_calls/cc-mismatch.stderr
index 61ddea64472..589e30d632e 100644
--- a/src/tools/miri/tests/fail/tail_calls/cc-mismatch.stderr
+++ b/src/tools/miri/tests/fail/tail_calls/cc-mismatch.stderr
@@ -11,12 +11,12 @@ LL |     extern "rust-call" fn call_once(self, args: Args) -> Self::Output;
    = note: inside `std::sys::backtrace::__rust_begin_short_backtrace::<fn(), ()>` at RUSTLIB/std/src/sys/backtrace.rs:LL:CC
    = note: inside closure at RUSTLIB/std/src/rt.rs:LL:CC
    = note: inside `std::ops::function::impls::<impl std::ops::FnOnce<()> for &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe>::call_once` at RUSTLIB/core/src/ops/function.rs:LL:CC
-   = note: inside `std::panicking::r#try::do_call::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32>` at RUSTLIB/std/src/panicking.rs:LL:CC
-   = note: inside `std::panicking::r#try::<i32, &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe>` at RUSTLIB/std/src/panicking.rs:LL:CC
+   = note: inside `std::panicking::catch_unwind::do_call::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32>` at RUSTLIB/std/src/panicking.rs:LL:CC
+   = note: inside `std::panicking::catch_unwind::<i32, &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe>` at RUSTLIB/std/src/panicking.rs:LL:CC
    = note: inside `std::panic::catch_unwind::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32>` at RUSTLIB/std/src/panic.rs:LL:CC
    = note: inside closure at RUSTLIB/std/src/rt.rs:LL:CC
-   = note: inside `std::panicking::r#try::do_call::<{closure@std::rt::lang_start_internal::{closure#0}}, isize>` at RUSTLIB/std/src/panicking.rs:LL:CC
-   = note: inside `std::panicking::r#try::<isize, {closure@std::rt::lang_start_internal::{closure#0}}>` at RUSTLIB/std/src/panicking.rs:LL:CC
+   = note: inside `std::panicking::catch_unwind::do_call::<{closure@std::rt::lang_start_internal::{closure#0}}, isize>` at RUSTLIB/std/src/panicking.rs:LL:CC
+   = note: inside `std::panicking::catch_unwind::<isize, {closure@std::rt::lang_start_internal::{closure#0}}>` at RUSTLIB/std/src/panicking.rs:LL:CC
    = note: inside `std::panic::catch_unwind::<{closure@std::rt::lang_start_internal::{closure#0}}, isize>` at RUSTLIB/std/src/panic.rs:LL:CC
    = note: inside `std::rt::lang_start_internal` at RUSTLIB/std/src/rt.rs:LL:CC
    = note: inside `std::rt::lang_start::<()>` at RUSTLIB/std/src/rt.rs:LL:CC
diff --git a/src/tools/miri/tests/pass/backtrace/backtrace-api-v1.stderr b/src/tools/miri/tests/pass/backtrace/backtrace-api-v1.stderr
index 1ee5298f17d..8e167dbadef 100644
--- a/src/tools/miri/tests/pass/backtrace/backtrace-api-v1.stderr
+++ b/src/tools/miri/tests/pass/backtrace/backtrace-api-v1.stderr
@@ -7,12 +7,12 @@ RUSTLIB/core/src/ops/function.rs:LL:CC (<fn() as std::ops::FnOnce<()>>::call_onc
 RUSTLIB/std/src/sys/backtrace.rs:LL:CC (std::sys::backtrace::__rust_begin_short_backtrace)
 RUSTLIB/std/src/rt.rs:LL:CC (std::rt::lang_start::{closure#0})
 RUSTLIB/core/src/ops/function.rs:LL:CC (std::ops::function::impls::call_once)
-RUSTLIB/std/src/panicking.rs:LL:CC (std::panicking::r#try::do_call)
-RUSTLIB/std/src/panicking.rs:LL:CC (std::panicking::r#try)
+RUSTLIB/std/src/panicking.rs:LL:CC (std::panicking::catch_unwind::do_call)
+RUSTLIB/std/src/panicking.rs:LL:CC (std::panicking::catch_unwind)
 RUSTLIB/std/src/panic.rs:LL:CC (std::panic::catch_unwind)
 RUSTLIB/std/src/rt.rs:LL:CC (std::rt::lang_start_internal::{closure#0})
-RUSTLIB/std/src/panicking.rs:LL:CC (std::panicking::r#try::do_call)
-RUSTLIB/std/src/panicking.rs:LL:CC (std::panicking::r#try)
+RUSTLIB/std/src/panicking.rs:LL:CC (std::panicking::catch_unwind::do_call)
+RUSTLIB/std/src/panicking.rs:LL:CC (std::panicking::catch_unwind)
 RUSTLIB/std/src/panic.rs:LL:CC (std::panic::catch_unwind)
 RUSTLIB/std/src/rt.rs:LL:CC (std::rt::lang_start_internal)
 RUSTLIB/std/src/rt.rs:LL:CC (std::rt::lang_start)
diff --git a/src/tools/miri/tests/pass/backtrace/backtrace-global-alloc.stderr b/src/tools/miri/tests/pass/backtrace/backtrace-global-alloc.stderr
index 26cdee18e3c..588bb85f35a 100644
--- a/src/tools/miri/tests/pass/backtrace/backtrace-global-alloc.stderr
+++ b/src/tools/miri/tests/pass/backtrace/backtrace-global-alloc.stderr
@@ -8,17 +8,17 @@
  at RUSTLIB/std/src/rt.rs:LL:CC
    4: std::ops::function::impls::call_once
  at RUSTLIB/core/src/ops/function.rs:LL:CC
-   5: std::panicking::r#try::do_call
+   5: std::panicking::catch_unwind::do_call
  at RUSTLIB/std/src/panicking.rs:LL:CC
-   6: std::panicking::r#try
+   6: std::panicking::catch_unwind
  at RUSTLIB/std/src/panicking.rs:LL:CC
    7: std::panic::catch_unwind
  at RUSTLIB/std/src/panic.rs:LL:CC
    8: std::rt::lang_start_internal::{closure#0}
  at RUSTLIB/std/src/rt.rs:LL:CC
-   9: std::panicking::r#try::do_call
+   9: std::panicking::catch_unwind::do_call
  at RUSTLIB/std/src/panicking.rs:LL:CC
-  10: std::panicking::r#try
+  10: std::panicking::catch_unwind
  at RUSTLIB/std/src/panicking.rs:LL:CC
   11: std::panic::catch_unwind
  at RUSTLIB/std/src/panic.rs:LL:CC
diff --git a/src/tools/miri/tests/pass/backtrace/backtrace-std.stderr b/src/tools/miri/tests/pass/backtrace/backtrace-std.stderr
index d89ae3837b9..9c952755957 100644
--- a/src/tools/miri/tests/pass/backtrace/backtrace-std.stderr
+++ b/src/tools/miri/tests/pass/backtrace/backtrace-std.stderr
@@ -16,17 +16,17 @@
  at RUSTLIB/std/src/rt.rs:LL:CC
    8: std::ops::function::impls::call_once
  at RUSTLIB/core/src/ops/function.rs:LL:CC
-   9: std::panicking::r#try::do_call
+   9: std::panicking::catch_unwind::do_call
  at RUSTLIB/std/src/panicking.rs:LL:CC
-  10: std::panicking::r#try
+  10: std::panicking::catch_unwind
  at RUSTLIB/std/src/panicking.rs:LL:CC
   11: std::panic::catch_unwind
  at RUSTLIB/std/src/panic.rs:LL:CC
   12: std::rt::lang_start_internal::{closure#0}
  at RUSTLIB/std/src/rt.rs:LL:CC
-  13: std::panicking::r#try::do_call
+  13: std::panicking::catch_unwind::do_call
  at RUSTLIB/std/src/panicking.rs:LL:CC
-  14: std::panicking::r#try
+  14: std::panicking::catch_unwind
  at RUSTLIB/std/src/panicking.rs:LL:CC
   15: std::panic::catch_unwind
  at RUSTLIB/std/src/panic.rs:LL:CC
diff --git a/src/tools/rustbook/Cargo.lock b/src/tools/rustbook/Cargo.lock
index 0b389377011..5c862e95400 100644
--- a/src/tools/rustbook/Cargo.lock
+++ b/src/tools/rustbook/Cargo.lock
@@ -344,17 +344,6 @@ dependencies = [
 ]
 
 [[package]]
-name = "dbus"
-version = "0.9.7"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1bb21987b9fb1613058ba3843121dd18b163b254d8a6e797e144cbac14d96d1b"
-dependencies = [
- "libc",
- "libdbus-sys",
- "winapi",
-]
-
-[[package]]
 name = "derive_builder"
 version = "0.20.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -824,16 +813,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d750af042f7ef4f724306de029d18836c26c1765a54a6a3f094cbd23a7267ffa"
 
 [[package]]
-name = "libdbus-sys"
-version = "0.2.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "06085512b750d640299b79be4bad3d2fa90a9c00b1fd9e1b46364f66f0485c72"
-dependencies = [
- "cc",
- "pkg-config",
-]
-
-[[package]]
 name = "linereader"
 version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -906,9 +885,9 @@ dependencies = [
 
 [[package]]
 name = "mdbook"
-version = "0.4.49"
+version = "0.4.50"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d1daacee059634081dee4250d2814763a365b92dfe14bfdef964bc27835209d4"
+checksum = "f72bc08f096e1fb15cfc382babe218317c2897d2040f967c4db40d156ca28e21"
 dependencies = [
  "ammonia",
  "anyhow",
@@ -921,7 +900,6 @@ dependencies = [
  "hex",
  "log",
  "memchr",
- "once_cell",
  "opener",
  "pulldown-cmark 0.10.3",
  "regex",
@@ -1070,12 +1048,11 @@ dependencies = [
 
 [[package]]
 name = "opener"
-version = "0.7.2"
+version = "0.8.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d0812e5e4df08da354c851a3376fead46db31c2214f849d3de356d774d057681"
+checksum = "de96cad6ee771be7f68df884d3767460b4684012308d8342ed5623fe62b2628c"
 dependencies = [
  "bstr",
- "dbus",
  "normpath",
  "windows-sys",
 ]
@@ -1906,22 +1883,6 @@ dependencies = [
 ]
 
 [[package]]
-name = "winapi"
-version = "0.3.9"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5c839a674fcd7a98952e593242ea400abe93992746761e38641405d28b00f419"
-dependencies = [
- "winapi-i686-pc-windows-gnu",
- "winapi-x86_64-pc-windows-gnu",
-]
-
-[[package]]
-name = "winapi-i686-pc-windows-gnu"
-version = "0.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
-
-[[package]]
 name = "winapi-util"
 version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1931,12 +1892,6 @@ dependencies = [
 ]
 
 [[package]]
-name = "winapi-x86_64-pc-windows-gnu"
-version = "0.4.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
-
-[[package]]
 name = "windows-core"
 version = "0.61.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
diff --git a/src/tools/rustbook/Cargo.toml b/src/tools/rustbook/Cargo.toml
index 10fde31306d..ee2ada5aa2b 100644
--- a/src/tools/rustbook/Cargo.toml
+++ b/src/tools/rustbook/Cargo.toml
@@ -15,6 +15,6 @@ mdbook-i18n-helpers = "0.3.3"
 mdbook-spec = { path = "../../doc/reference/mdbook-spec" }
 
 [dependencies.mdbook]
-version = "0.4.49"
+version = "0.4.50"
 default-features = false
 features = ["search"]
diff --git a/tests/assembly/asm/aarch64-types.rs b/tests/assembly/asm/aarch64-types.rs
index ad2770d43e3..b7abeb02298 100644
--- a/tests/assembly/asm/aarch64-types.rs
+++ b/tests/assembly/asm/aarch64-types.rs
@@ -86,12 +86,11 @@ pub unsafe fn sym_static() {
 
 // Regression test for #75761
 // CHECK-LABEL: {{("#)?}}issue_75761{{"?}}
-// aarch64: str {{.*}}x30
-// arm64ec: stp {{.*}}x30
+// x29 holds the frame pointer, right next to x30, so ldp/stp happens sometimes
+// CHECK: st[[MAY_PAIR:(r|p).*]]x30
 // CHECK: //APP
 // CHECK: //NO_APP
-// aarch64: ldr {{.*}}x30
-// arm64ec: ldp {{.*}}x30
+// CHECK: ld[[MAY_PAIR]]x30
 #[no_mangle]
 pub unsafe fn issue_75761() {
     asm!("", out("v0") _, out("x30") _);
diff --git a/tests/codegen/frame-pointer.rs b/tests/codegen/frame-pointer.rs
index 1f7c9a59c98..23989653fa8 100644
--- a/tests/codegen/frame-pointer.rs
+++ b/tests/codegen/frame-pointer.rs
@@ -26,8 +26,10 @@ pub fn peach(x: u32) -> u32 {
 
 // CHECK: attributes [[PEACH_ATTRS]] = {
 // x64-linux-NOT: {{.*}}"frame-pointer"{{.*}}
-// aarch64-linux-NOT: {{.*}}"frame-pointer"{{.*}}
 // x64-apple-SAME: {{.*}}"frame-pointer"="all"
 // force-SAME: {{.*}}"frame-pointer"="all"
+//
+// AAPCS64 demands frame pointers:
+// aarch64-linux-SAME: {{.*}}"frame-pointer"="non-leaf"
 // aarch64-apple-SAME: {{.*}}"frame-pointer"="non-leaf"
 // CHECK-SAME: }
diff --git a/tests/crashes/122704.rs b/tests/crashes/122704.rs
deleted file mode 100644
index d6c07be8318..00000000000
--- a/tests/crashes/122704.rs
+++ /dev/null
@@ -1,14 +0,0 @@
-//@ known-bug: #122704
-use std::any::Any;
-
-pub struct Foo {
-    bar: Box<dyn for<'a> Fn(&'a usize) -> Box<dyn Any + 'a>>,
-}
-
-impl Foo {
-    pub fn ack<I>(&mut self, f: impl for<'a> Fn(&'a usize) -> Box<I>) {
-        self.bar = Box::new(|baz| Box::new(f(baz)));
-    }
-}
-
-fn main() {}
diff --git a/tests/crashes/133199.rs b/tests/crashes/133199.rs
deleted file mode 100644
index 76535fa83a6..00000000000
--- a/tests/crashes/133199.rs
+++ /dev/null
@@ -1,11 +0,0 @@
-//@ known-bug: #133199
-//@ aux-build: aux133199.rs
-
-extern crate aux133199;
-
-use aux133199::FixedBitSet;
-
-fn main() {
-    FixedBitSet::<7>::new();
-    //~^ ERROR
-}
diff --git a/tests/crashes/136894.rs b/tests/crashes/136894.rs
deleted file mode 100644
index 26bbb78717e..00000000000
--- a/tests/crashes/136894.rs
+++ /dev/null
@@ -1,8 +0,0 @@
-//@ known-bug: #136894
-#![feature(generic_const_exprs)]
-#![crate_type = "lib"]
-#![allow(incomplete_features, dead_code)]
-
-struct X<T>([(); f::<T>()]) where [(); f::<T>()]:;
-
-const fn f<T>() -> usize { panic!() }
diff --git a/tests/crashes/137813.rs b/tests/crashes/137813.rs
deleted file mode 100644
index 5d205ee5331..00000000000
--- a/tests/crashes/137813.rs
+++ /dev/null
@@ -1,18 +0,0 @@
-//@ known-bug: #137813
-trait AssocConst {
-    const A: u8;
-}
-
-impl<T> AssocConst for (T,) {
-    const A: u8 = 0;
-}
-
-trait Trait {}
-
-impl<U> Trait for () where (U,): AssocConst<A = { 0 }> {}
-
-fn foo()
-where
-    (): Trait,
-{
-}
diff --git a/tests/crashes/140642.rs b/tests/crashes/140642.rs
deleted file mode 100644
index ff75a6ec2f2..00000000000
--- a/tests/crashes/140642.rs
+++ /dev/null
@@ -1,8 +0,0 @@
-//@ known-bug: #140642
-#![feature(min_generic_const_args)]
-
-pub trait Tr<A> {
-    const SIZE: usize;
-}
-
-fn mk_array(_x: T) -> [(); <T as Tr<bool>>::SIZE] {}
diff --git a/tests/debuginfo/multiline-calls.rs b/tests/debuginfo/multiline-calls.rs
new file mode 100644
index 00000000000..724ad29729f
--- /dev/null
+++ b/tests/debuginfo/multiline-calls.rs
@@ -0,0 +1,35 @@
+//@ compile-flags:-g
+//@ min-gdb-version: 16.0
+
+// === GDB TESTS ===================================================================================
+
+// gdb-command: run
+// gdb-check:[...]#break[...]
+// gdb-command: up
+// gdb-check:[...]zzz[...]
+
+// === LLDB TESTS ==================================================================================
+
+// lldb-command:run
+// lldb-check:[...]#break[...]
+// lldb-command: up
+// lldb-check:[...]zzz[...]
+
+struct Foo;
+
+impl Foo {
+    fn bar(self) -> Foo {
+        println!("bar");
+        self
+    }
+    fn baz(self) -> Foo {
+        println!("baz"); // #break
+        self
+    }
+}
+
+fn main() {
+    let f = Foo;
+    f.bar()              // aaa
+        .baz();          // zzz
+}
diff --git a/tests/mir-opt/address_of.address_of_reborrow.SimplifyCfg-initial.after.mir b/tests/mir-opt/address_of.address_of_reborrow.SimplifyCfg-initial.after.mir
index 5fc77f95eaf..8afb6ad250e 100644
--- a/tests/mir-opt/address_of.address_of_reborrow.SimplifyCfg-initial.after.mir
+++ b/tests/mir-opt/address_of.address_of_reborrow.SimplifyCfg-initial.after.mir
@@ -1,34 +1,34 @@
 // MIR for `address_of_reborrow` after SimplifyCfg-initial
 
 | User Type Annotations
-| 0: user_ty: Canonical { value: Ty(*const ^0), max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }] }, span: $DIR/address_of.rs:8:10: 8:18, inferred_ty: *const [i32; 10]
-| 1: user_ty: Canonical { value: Ty(*const dyn std::marker::Send), max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }] }, span: $DIR/address_of.rs:10:10: 10:25, inferred_ty: *const dyn std::marker::Send
-| 2: user_ty: Canonical { value: Ty(*const ^0), max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }] }, span: $DIR/address_of.rs:14:12: 14:20, inferred_ty: *const [i32; 10]
-| 3: user_ty: Canonical { value: Ty(*const ^0), max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }] }, span: $DIR/address_of.rs:14:12: 14:20, inferred_ty: *const [i32; 10]
+| 0: user_ty: Canonical { value: Ty(*const ^0), max_universe: U0, variables: [Ty(General(U0))] }, span: $DIR/address_of.rs:8:10: 8:18, inferred_ty: *const [i32; 10]
+| 1: user_ty: Canonical { value: Ty(*const dyn std::marker::Send), max_universe: U0, variables: [Region(U0)] }, span: $DIR/address_of.rs:10:10: 10:25, inferred_ty: *const dyn std::marker::Send
+| 2: user_ty: Canonical { value: Ty(*const ^0), max_universe: U0, variables: [Ty(General(U0))] }, span: $DIR/address_of.rs:14:12: 14:20, inferred_ty: *const [i32; 10]
+| 3: user_ty: Canonical { value: Ty(*const ^0), max_universe: U0, variables: [Ty(General(U0))] }, span: $DIR/address_of.rs:14:12: 14:20, inferred_ty: *const [i32; 10]
 | 4: user_ty: Canonical { value: Ty(*const [i32; 10]), max_universe: U0, variables: [] }, span: $DIR/address_of.rs:15:12: 15:28, inferred_ty: *const [i32; 10]
 | 5: user_ty: Canonical { value: Ty(*const [i32; 10]), max_universe: U0, variables: [] }, span: $DIR/address_of.rs:15:12: 15:28, inferred_ty: *const [i32; 10]
-| 6: user_ty: Canonical { value: Ty(*const dyn std::marker::Send), max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }] }, span: $DIR/address_of.rs:16:12: 16:27, inferred_ty: *const dyn std::marker::Send
-| 7: user_ty: Canonical { value: Ty(*const dyn std::marker::Send), max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }] }, span: $DIR/address_of.rs:16:12: 16:27, inferred_ty: *const dyn std::marker::Send
+| 6: user_ty: Canonical { value: Ty(*const dyn std::marker::Send), max_universe: U0, variables: [Region(U0)] }, span: $DIR/address_of.rs:16:12: 16:27, inferred_ty: *const dyn std::marker::Send
+| 7: user_ty: Canonical { value: Ty(*const dyn std::marker::Send), max_universe: U0, variables: [Region(U0)] }, span: $DIR/address_of.rs:16:12: 16:27, inferred_ty: *const dyn std::marker::Send
 | 8: user_ty: Canonical { value: Ty(*const [i32]), max_universe: U0, variables: [] }, span: $DIR/address_of.rs:17:12: 17:24, inferred_ty: *const [i32]
 | 9: user_ty: Canonical { value: Ty(*const [i32]), max_universe: U0, variables: [] }, span: $DIR/address_of.rs:17:12: 17:24, inferred_ty: *const [i32]
-| 10: user_ty: Canonical { value: Ty(*const ^0), max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }] }, span: $DIR/address_of.rs:19:10: 19:18, inferred_ty: *const [i32; 10]
-| 11: user_ty: Canonical { value: Ty(*const dyn std::marker::Send), max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }] }, span: $DIR/address_of.rs:21:10: 21:25, inferred_ty: *const dyn std::marker::Send
-| 12: user_ty: Canonical { value: Ty(*const ^0), max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }] }, span: $DIR/address_of.rs:24:12: 24:20, inferred_ty: *const [i32; 10]
-| 13: user_ty: Canonical { value: Ty(*const ^0), max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }] }, span: $DIR/address_of.rs:24:12: 24:20, inferred_ty: *const [i32; 10]
+| 10: user_ty: Canonical { value: Ty(*const ^0), max_universe: U0, variables: [Ty(General(U0))] }, span: $DIR/address_of.rs:19:10: 19:18, inferred_ty: *const [i32; 10]
+| 11: user_ty: Canonical { value: Ty(*const dyn std::marker::Send), max_universe: U0, variables: [Region(U0)] }, span: $DIR/address_of.rs:21:10: 21:25, inferred_ty: *const dyn std::marker::Send
+| 12: user_ty: Canonical { value: Ty(*const ^0), max_universe: U0, variables: [Ty(General(U0))] }, span: $DIR/address_of.rs:24:12: 24:20, inferred_ty: *const [i32; 10]
+| 13: user_ty: Canonical { value: Ty(*const ^0), max_universe: U0, variables: [Ty(General(U0))] }, span: $DIR/address_of.rs:24:12: 24:20, inferred_ty: *const [i32; 10]
 | 14: user_ty: Canonical { value: Ty(*const [i32; 10]), max_universe: U0, variables: [] }, span: $DIR/address_of.rs:25:12: 25:28, inferred_ty: *const [i32; 10]
 | 15: user_ty: Canonical { value: Ty(*const [i32; 10]), max_universe: U0, variables: [] }, span: $DIR/address_of.rs:25:12: 25:28, inferred_ty: *const [i32; 10]
-| 16: user_ty: Canonical { value: Ty(*const dyn std::marker::Send), max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }] }, span: $DIR/address_of.rs:26:12: 26:27, inferred_ty: *const dyn std::marker::Send
-| 17: user_ty: Canonical { value: Ty(*const dyn std::marker::Send), max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }] }, span: $DIR/address_of.rs:26:12: 26:27, inferred_ty: *const dyn std::marker::Send
+| 16: user_ty: Canonical { value: Ty(*const dyn std::marker::Send), max_universe: U0, variables: [Region(U0)] }, span: $DIR/address_of.rs:26:12: 26:27, inferred_ty: *const dyn std::marker::Send
+| 17: user_ty: Canonical { value: Ty(*const dyn std::marker::Send), max_universe: U0, variables: [Region(U0)] }, span: $DIR/address_of.rs:26:12: 26:27, inferred_ty: *const dyn std::marker::Send
 | 18: user_ty: Canonical { value: Ty(*const [i32]), max_universe: U0, variables: [] }, span: $DIR/address_of.rs:27:12: 27:24, inferred_ty: *const [i32]
 | 19: user_ty: Canonical { value: Ty(*const [i32]), max_universe: U0, variables: [] }, span: $DIR/address_of.rs:27:12: 27:24, inferred_ty: *const [i32]
-| 20: user_ty: Canonical { value: Ty(*mut ^0), max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }] }, span: $DIR/address_of.rs:29:10: 29:16, inferred_ty: *mut [i32; 10]
-| 21: user_ty: Canonical { value: Ty(*mut dyn std::marker::Send), max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }] }, span: $DIR/address_of.rs:31:10: 31:23, inferred_ty: *mut dyn std::marker::Send
-| 22: user_ty: Canonical { value: Ty(*mut ^0), max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }] }, span: $DIR/address_of.rs:34:12: 34:18, inferred_ty: *mut [i32; 10]
-| 23: user_ty: Canonical { value: Ty(*mut ^0), max_universe: U0, variables: [CanonicalVarInfo { kind: Ty(General(U0)) }] }, span: $DIR/address_of.rs:34:12: 34:18, inferred_ty: *mut [i32; 10]
+| 20: user_ty: Canonical { value: Ty(*mut ^0), max_universe: U0, variables: [Ty(General(U0))] }, span: $DIR/address_of.rs:29:10: 29:16, inferred_ty: *mut [i32; 10]
+| 21: user_ty: Canonical { value: Ty(*mut dyn std::marker::Send), max_universe: U0, variables: [Region(U0)] }, span: $DIR/address_of.rs:31:10: 31:23, inferred_ty: *mut dyn std::marker::Send
+| 22: user_ty: Canonical { value: Ty(*mut ^0), max_universe: U0, variables: [Ty(General(U0))] }, span: $DIR/address_of.rs:34:12: 34:18, inferred_ty: *mut [i32; 10]
+| 23: user_ty: Canonical { value: Ty(*mut ^0), max_universe: U0, variables: [Ty(General(U0))] }, span: $DIR/address_of.rs:34:12: 34:18, inferred_ty: *mut [i32; 10]
 | 24: user_ty: Canonical { value: Ty(*mut [i32; 10]), max_universe: U0, variables: [] }, span: $DIR/address_of.rs:35:12: 35:26, inferred_ty: *mut [i32; 10]
 | 25: user_ty: Canonical { value: Ty(*mut [i32; 10]), max_universe: U0, variables: [] }, span: $DIR/address_of.rs:35:12: 35:26, inferred_ty: *mut [i32; 10]
-| 26: user_ty: Canonical { value: Ty(*mut dyn std::marker::Send), max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }] }, span: $DIR/address_of.rs:36:12: 36:25, inferred_ty: *mut dyn std::marker::Send
-| 27: user_ty: Canonical { value: Ty(*mut dyn std::marker::Send), max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }] }, span: $DIR/address_of.rs:36:12: 36:25, inferred_ty: *mut dyn std::marker::Send
+| 26: user_ty: Canonical { value: Ty(*mut dyn std::marker::Send), max_universe: U0, variables: [Region(U0)] }, span: $DIR/address_of.rs:36:12: 36:25, inferred_ty: *mut dyn std::marker::Send
+| 27: user_ty: Canonical { value: Ty(*mut dyn std::marker::Send), max_universe: U0, variables: [Region(U0)] }, span: $DIR/address_of.rs:36:12: 36:25, inferred_ty: *mut dyn std::marker::Send
 | 28: user_ty: Canonical { value: Ty(*mut [i32]), max_universe: U0, variables: [] }, span: $DIR/address_of.rs:37:12: 37:22, inferred_ty: *mut [i32]
 | 29: user_ty: Canonical { value: Ty(*mut [i32]), max_universe: U0, variables: [] }, span: $DIR/address_of.rs:37:12: 37:22, inferred_ty: *mut [i32]
 |
diff --git a/tests/mir-opt/building/receiver_ptr_mutability.main.built.after.mir b/tests/mir-opt/building/receiver_ptr_mutability.main.built.after.mir
index 6e349a2a24f..744553c7cd2 100644
--- a/tests/mir-opt/building/receiver_ptr_mutability.main.built.after.mir
+++ b/tests/mir-opt/building/receiver_ptr_mutability.main.built.after.mir
@@ -3,8 +3,8 @@
 | User Type Annotations
 | 0: user_ty: Canonical { value: Ty(*mut Test), max_universe: U0, variables: [] }, span: $DIR/receiver_ptr_mutability.rs:15:14: 15:23, inferred_ty: *mut Test
 | 1: user_ty: Canonical { value: Ty(*mut Test), max_universe: U0, variables: [] }, span: $DIR/receiver_ptr_mutability.rs:15:14: 15:23, inferred_ty: *mut Test
-| 2: user_ty: Canonical { value: Ty(&&&&*mut Test), max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }] }, span: $DIR/receiver_ptr_mutability.rs:19:18: 19:31, inferred_ty: &&&&*mut Test
-| 3: user_ty: Canonical { value: Ty(&&&&*mut Test), max_universe: U0, variables: [CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }, CanonicalVarInfo { kind: Region(U0) }] }, span: $DIR/receiver_ptr_mutability.rs:19:18: 19:31, inferred_ty: &&&&*mut Test
+| 2: user_ty: Canonical { value: Ty(&&&&*mut Test), max_universe: U0, variables: [Region(U0), Region(U0), Region(U0), Region(U0)] }, span: $DIR/receiver_ptr_mutability.rs:19:18: 19:31, inferred_ty: &&&&*mut Test
+| 3: user_ty: Canonical { value: Ty(&&&&*mut Test), max_universe: U0, variables: [Region(U0), Region(U0), Region(U0), Region(U0)] }, span: $DIR/receiver_ptr_mutability.rs:19:18: 19:31, inferred_ty: &&&&*mut Test
 |
 fn main() -> () {
     let mut _0: ();
diff --git a/tests/rustdoc-js/auxiliary/interner.rs b/tests/rustdoc-js/auxiliary/interner.rs
index e4e4ff6276d..8af3b732ef7 100644
--- a/tests/rustdoc-js/auxiliary/interner.rs
+++ b/tests/rustdoc-js/auxiliary/interner.rs
@@ -18,7 +18,7 @@ pub trait Interner: Sized {
     type Binder<T: TypeVisitable<Self>>: BoundVars<Self> + TypeSuperVisitable<Self>;
     type BoundVars: IntoIterator<Item = Self::BoundVar>;
     type BoundVar;
-    type CanonicalVars: Copy + Debug + Hash + Eq + IntoIterator<Item = CanonicalVarInfo<Self>>;
+    type CanonicalVarKinds: Copy + Debug + Hash + Eq + IntoIterator<Item = CanonicalVarKind<Self>>;
     type Ty: Copy
         + DebugWithInfcx<Self>
         + Hash
@@ -77,7 +77,7 @@ pub trait Interner: Sized {
     type ClosureKind: Copy + Debug + Hash + Eq;
 
     // Required method
-    fn mk_canonical_var_infos(self, infos: &[CanonicalVarInfo<Self>]) -> Self::CanonicalVars;
+    fn mk_canonical_var_kinds(self, kinds: &[CanonicalVarKind<Self>]) -> Self::CanonicalVarKinds;
 }
 
 pub trait DebugWithInfcx<I: Interner>: Debug {
@@ -104,10 +104,6 @@ pub trait TypeSuperVisitable<I: Interner>: TypeVisitable<I> {
     fn super_visit_with<V: TypeVisitor<I>>(&self, visitor: &mut V) -> V::Result;
 }
 
-pub struct CanonicalVarInfo<I: Interner> {
-    pub kind: CanonicalVarKind<I>,
-}
-
 pub struct CanonicalVarKind<I>(std::marker::PhantomData<I>);
 
 pub struct TyKind<I>(std::marker::PhantomData<I>);
diff --git a/tests/rustdoc-js/looks-like-rustc-interner.js b/tests/rustdoc-js/looks-like-rustc-interner.js
index d6d2764c3ae..7d051194454 100644
--- a/tests/rustdoc-js/looks-like-rustc-interner.js
+++ b/tests/rustdoc-js/looks-like-rustc-interner.js
@@ -3,13 +3,13 @@
 
 const EXPECTED = [
     {
-        'query': 'canonicalvarinfo, intoiterator -> intoiterator',
+        'query': 'CanonicalVarKind, intoiterator -> intoiterator',
         'others': [],
     },
     {
-        'query': '[canonicalvarinfo], interner<tys=intoiterator> -> intoiterator',
+        'query': '[CanonicalVarKind], interner<tys=intoiterator> -> intoiterator',
         'others': [
-            { 'path': 'looks_like_rustc_interner::Interner', 'name': 'mk_canonical_var_infos' },
+            { 'path': 'looks_like_rustc_interner::Interner', 'name': 'mk_canonical_var_kinds' },
         ],
     },
 ];
diff --git a/tests/rustdoc-json/attrs/repr_combination.rs b/tests/rustdoc-json/attrs/repr_combination.rs
index 0e8e2ef0d83..6fe29c5eac0 100644
--- a/tests/rustdoc-json/attrs/repr_combination.rs
+++ b/tests/rustdoc-json/attrs/repr_combination.rs
@@ -77,3 +77,7 @@ pub enum AlignedExplicitRepr {
 pub enum ReorderedAlignedExplicitRepr {
     First,
 }
+
+//@ is "$.index[?(@.name=='Transparent')].attrs" '["#[repr(transparent)]"]'
+#[repr(transparent)]
+pub struct Transparent(i64);
diff --git a/tests/rustdoc-json/attrs/repr_transparent.rs b/tests/rustdoc-json/attrs/repr_transparent.rs
deleted file mode 100644
index 1e634ca901d..00000000000
--- a/tests/rustdoc-json/attrs/repr_transparent.rs
+++ /dev/null
@@ -1,37 +0,0 @@
-#![no_std]
-
-// Rustdoc JSON *only* includes `#[repr(transparent)]`
-// if the transparency is public API:
-// - if a non-1-ZST field exists, it has to be public
-// - otherwise, all fields are 1-ZST and at least one of them is public
-//
-// More info: https://doc.rust-lang.org/nomicon/other-reprs.html#reprtransparent
-
-// Here, the non-1-ZST field is public.
-// We expect `#[repr(transparent)]` in the attributes.
-//
-//@ is "$.index[?(@.name=='Transparent')].attrs" '["#[repr(transparent)]"]'
-#[repr(transparent)]
-pub struct Transparent(pub i64);
-
-// Here the non-1-ZST field isn't public, so the attribute isn't included.
-//
-//@ has "$.index[?(@.name=='TransparentNonPub')]"
-//@ is "$.index[?(@.name=='TransparentNonPub')].attrs" '[]'
-#[repr(transparent)]
-pub struct TransparentNonPub(i64);
-
-// Only 1-ZST fields here, and one of them is public.
-// We expect `#[repr(transparent)]` in the attributes.
-//
-//@ is "$.index[?(@.name=='AllZst')].attrs" '["#[repr(transparent)]"]'
-#[repr(transparent)]
-pub struct AllZst<'a>(pub core::marker::PhantomData<&'a ()>, ());
-
-// Only 1-ZST fields here but none of them are public.
-// The attribute isn't included.
-//
-//@ has "$.index[?(@.name=='AllZstNotPublic')]"
-//@ is "$.index[?(@.name=='AllZstNotPublic')].attrs" '[]'
-#[repr(transparent)]
-pub struct AllZstNotPublic<'a>(core::marker::PhantomData<&'a ()>, ());
diff --git a/tests/rustdoc-ui/intra-doc/warning.stderr b/tests/rustdoc-ui/intra-doc/warning.stderr
index 3a06f1787e0..9b3f6f822d7 100644
--- a/tests/rustdoc-ui/intra-doc/warning.stderr
+++ b/tests/rustdoc-ui/intra-doc/warning.stderr
@@ -69,29 +69,19 @@ LL | bar [BarC] bar
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 warning: unresolved link to `BarD`
-  --> $DIR/warning.rs:45:9
+  --> $DIR/warning.rs:45:20
    |
 LL | #[doc = "Foo\nbar [BarD] bar\nbaz"]
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                    ^^^^ no item named `BarD` in scope
    |
-   = note: the link appears in this line:
-           
-           bar [BarD] bar
-                ^^^^
-   = note: no item named `BarD` in scope
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 warning: unresolved link to `BarF`
-  --> $DIR/warning.rs:54:4
+  --> $DIR/warning.rs:54:15
    |
 LL | f!("Foo\nbar [BarF] bar\nbaz");
-   |    ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |               ^^^^ no item named `BarF` in scope
    |
-   = note: the link appears in this line:
-           
-           bar [BarF] bar
-                ^^^^
-   = note: no item named `BarF` in scope
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
    = note: this warning originates in the macro `f` (in Nightly builds, run with -Z macro-backtrace for more info)
 
@@ -112,29 +102,19 @@ LL |  * time to introduce a link [error]
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 warning: unresolved link to `error`
-  --> $DIR/warning.rs:68:9
+  --> $DIR/warning.rs:68:23
    |
 LL | #[doc = "single line [error]"]
-   |         ^^^^^^^^^^^^^^^^^^^^^
+   |                       ^^^^^ no item named `error` in scope
    |
-   = note: the link appears in this line:
-           
-           single line [error]
-                        ^^^^^
-   = note: no item named `error` in scope
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 warning: unresolved link to `error`
-  --> $DIR/warning.rs:71:9
+  --> $DIR/warning.rs:71:41
    |
 LL | #[doc = "single line with \"escaping\" [error]"]
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                                         ^^^^^ no item named `error` in scope
    |
-   = note: the link appears in this line:
-           
-           single line with "escaping" [error]
-                                        ^^^^^
-   = note: no item named `error` in scope
    = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
 
 warning: unresolved link to `error`
diff --git a/tests/rustdoc-ui/lints/bare-urls-limit.rs b/tests/rustdoc-ui/lints/bare-urls-limit.rs
new file mode 100644
index 00000000000..f64154b0496
--- /dev/null
+++ b/tests/rustdoc-ui/lints/bare-urls-limit.rs
@@ -0,0 +1,12 @@
+//@ check-fail
+
+#![deny(rustdoc::bare_urls)]
+
+// examples of bare urls that are beyond our ability to generate suggestions for
+
+// this falls through every heuristic in `source_span_for_markdown_range`,
+// and thus does not get any suggestion.
+#[doc = "good: <https://example.com/> \n\n"]
+//~^ ERROR this URL is not a hyperlink
+#[doc = "bad: https://example.com/"]
+pub fn duplicate_raw() {}
diff --git a/tests/rustdoc-ui/lints/bare-urls-limit.stderr b/tests/rustdoc-ui/lints/bare-urls-limit.stderr
new file mode 100644
index 00000000000..9573665cb13
--- /dev/null
+++ b/tests/rustdoc-ui/lints/bare-urls-limit.stderr
@@ -0,0 +1,18 @@
+error: this URL is not a hyperlink
+  --> $DIR/bare-urls-limit.rs:9:9
+   |
+LL |   #[doc = "good: <https://example.com/> \n\n"]
+   |  _________^
+LL | |
+LL | | #[doc = "bad: https://example.com/"]
+   | |___________________________________^
+   |
+   = note: bare URLs are not automatically turned into clickable links
+note: the lint level is defined here
+  --> $DIR/bare-urls-limit.rs:3:9
+   |
+LL | #![deny(rustdoc::bare_urls)]
+   |         ^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
diff --git a/tests/rustdoc-ui/lints/bare-urls.fixed b/tests/rustdoc-ui/lints/bare-urls.fixed
index 7938d715199..a91573146b8 100644
--- a/tests/rustdoc-ui/lints/bare-urls.fixed
+++ b/tests/rustdoc-ui/lints/bare-urls.fixed
@@ -38,6 +38,16 @@
 //~^ ERROR this URL is not a hyperlink
 pub fn c() {}
 
+#[doc = "here's a thing: <https://example.com/>"]
+//~^ ERROR this URL is not a hyperlink
+pub fn f() {}
+
+/// <https://example.com/sugar>
+//~^ ERROR this URL is not a hyperlink
+#[doc = "<https://example.com/raw>"]
+//~^ ERROR this URL is not a hyperlink
+pub fn mixed() {}
+
 /// <https://somewhere.com>
 /// [a](http://a.com)
 /// [b]
diff --git a/tests/rustdoc-ui/lints/bare-urls.rs b/tests/rustdoc-ui/lints/bare-urls.rs
index 75f42b78ffb..5b008cdafa2 100644
--- a/tests/rustdoc-ui/lints/bare-urls.rs
+++ b/tests/rustdoc-ui/lints/bare-urls.rs
@@ -38,6 +38,16 @@
 //~^ ERROR this URL is not a hyperlink
 pub fn c() {}
 
+#[doc = "here's a thing: https://example.com/"]
+//~^ ERROR this URL is not a hyperlink
+pub fn f() {}
+
+/// https://example.com/sugar
+//~^ ERROR this URL is not a hyperlink
+#[doc = "https://example.com/raw"]
+//~^ ERROR this URL is not a hyperlink
+pub fn mixed() {}
+
 /// <https://somewhere.com>
 /// [a](http://a.com)
 /// [b]
diff --git a/tests/rustdoc-ui/lints/bare-urls.stderr b/tests/rustdoc-ui/lints/bare-urls.stderr
index ddfc387eaf6..e1108c7e7f8 100644
--- a/tests/rustdoc-ui/lints/bare-urls.stderr
+++ b/tests/rustdoc-ui/lints/bare-urls.stderr
@@ -207,5 +207,41 @@ help: use an automatic link instead
 LL | /// hey! <https://somewhere.com/a?hello=12&bye=11#xyz>
    |          +                                           +
 
-error: aborting due to 17 previous errors
+error: this URL is not a hyperlink
+  --> $DIR/bare-urls.rs:41:26
+   |
+LL | #[doc = "here's a thing: https://example.com/"]
+   |                          ^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: bare URLs are not automatically turned into clickable links
+help: use an automatic link instead
+   |
+LL | #[doc = "here's a thing: <https://example.com/>"]
+   |                          +                    +
+
+error: this URL is not a hyperlink
+  --> $DIR/bare-urls.rs:45:5
+   |
+LL | /// https://example.com/sugar
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: bare URLs are not automatically turned into clickable links
+help: use an automatic link instead
+   |
+LL | /// <https://example.com/sugar>
+   |     +                         +
+
+error: this URL is not a hyperlink
+  --> $DIR/bare-urls.rs:47:10
+   |
+LL | #[doc = "https://example.com/raw"]
+   |          ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: bare URLs are not automatically turned into clickable links
+help: use an automatic link instead
+   |
+LL | #[doc = "<https://example.com/raw>"]
+   |          +                       +
+
+error: aborting due to 20 previous errors
 
diff --git a/tests/rustdoc-ui/unescaped_backticks.stderr b/tests/rustdoc-ui/unescaped_backticks.stderr
index d93aaf5f3ca..1bcb88e108f 100644
--- a/tests/rustdoc-ui/unescaped_backticks.stderr
+++ b/tests/rustdoc-ui/unescaped_backticks.stderr
@@ -628,10 +628,10 @@ LL | /// or even to add a number `n` to 42 (`add(42, n)\`)!
    |                                                   +
 
 error: unescaped backtick
-  --> $DIR/unescaped_backticks.rs:108:9
+  --> $DIR/unescaped_backticks.rs:108:10
    |
 LL | #[doc = "`"]
-   |         ^^^
+   |          ^
    |
    = help: the opening or closing backtick of an inline code may be missing
    = help: if you meant to use a literal backtick, escape it
@@ -639,10 +639,10 @@ LL | #[doc = "`"]
            to this: \`
 
 error: unescaped backtick
-  --> $DIR/unescaped_backticks.rs:115:9
+  --> $DIR/unescaped_backticks.rs:115:26
    |
 LL | #[doc = concat!("\\", "`")]
-   |         ^^^^^^^^^^^^^^^^^^^^
+   |                          ^
    |
    = help: the opening backtick of an inline code may be missing
             change: \`
diff --git a/tests/ui/associated-inherent-types/not-found-self-type-differs-shadowing-trait-item.uncovered.stderr b/tests/ui/associated-inherent-types/not-found-self-type-differs-shadowing-trait-item.uncovered.stderr
index 978305c2ce3..3e914e0538d 100644
--- a/tests/ui/associated-inherent-types/not-found-self-type-differs-shadowing-trait-item.uncovered.stderr
+++ b/tests/ui/associated-inherent-types/not-found-self-type-differs-shadowing-trait-item.uncovered.stderr
@@ -2,7 +2,13 @@ error[E0223]: ambiguous associated type
   --> $DIR/not-found-self-type-differs-shadowing-trait-item.rs:28:12
    |
 LL |     let _: S::<bool>::Pr = ();
-   |            ^^^^^^^^^^^^^ help: use fully-qualified syntax: `<S<bool> as Tr>::Pr`
+   |            ^^^^^^^^^^^^^
+   |
+help: use fully-qualified syntax
+   |
+LL -     let _: S::<bool>::Pr = ();
+LL +     let _: <S<bool> as Tr>::Pr = ();
+   |
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/associated-item/ambiguous-associated-type-with-generics.stderr b/tests/ui/associated-item/ambiguous-associated-type-with-generics.stderr
index 9e1dd739807..fcf6b4c3e73 100644
--- a/tests/ui/associated-item/ambiguous-associated-type-with-generics.stderr
+++ b/tests/ui/associated-item/ambiguous-associated-type-with-generics.stderr
@@ -2,7 +2,12 @@ error[E0223]: ambiguous associated type
   --> $DIR/ambiguous-associated-type-with-generics.rs:13:13
    |
 LL |     let _x: <dyn Trait<i32>>::Ty;
-   |             ^^^^^^^^^^^^^^^^^^^^ help: use fully-qualified syntax: `<dyn Trait<i32> as Assoc>::Ty`
+   |             ^^^^^^^^^^^^^^^^^^^^
+   |
+help: use fully-qualified syntax
+   |
+LL |     let _x: <dyn Trait<i32> as Assoc>::Ty;
+   |                             ++++++++
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/associated-item/associated-item-duplicate-names-3.stderr b/tests/ui/associated-item/associated-item-duplicate-names-3.stderr
index a2346e292ac..84a9da09988 100644
--- a/tests/ui/associated-item/associated-item-duplicate-names-3.stderr
+++ b/tests/ui/associated-item/associated-item-duplicate-names-3.stderr
@@ -13,7 +13,13 @@ error[E0223]: ambiguous associated type
   --> $DIR/associated-item-duplicate-names-3.rs:18:12
    |
 LL |     let x: Baz::Bar = 5;
-   |            ^^^^^^^^ help: use fully-qualified syntax: `<Baz as Foo>::Bar`
+   |            ^^^^^^^^
+   |
+help: use fully-qualified syntax
+   |
+LL -     let x: Baz::Bar = 5;
+LL +     let x: <Baz as Foo>::Bar = 5;
+   |
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/associated-type-bounds/return-type-notation/path-no-qself.stderr b/tests/ui/associated-type-bounds/return-type-notation/path-no-qself.stderr
index aad6dfc496b..a13fdbda1bf 100644
--- a/tests/ui/associated-type-bounds/return-type-notation/path-no-qself.stderr
+++ b/tests/ui/associated-type-bounds/return-type-notation/path-no-qself.stderr
@@ -7,7 +7,7 @@ LL |     Trait::method(..): Send,
 help: if there were a type named `Example` that implemented `Trait`, you could use the fully-qualified path
    |
 LL -     Trait::method(..): Send,
-LL +     <Example as Trait>::method: Send,
+LL +     <Example as Trait>::method(..): Send,
    |
 
 error: aborting due to 1 previous error
diff --git a/tests/ui/associated-type-bounds/return-type-notation/path-non-param-qself.stderr b/tests/ui/associated-type-bounds/return-type-notation/path-non-param-qself.stderr
index 38202bdbf07..4c4c2c24079 100644
--- a/tests/ui/associated-type-bounds/return-type-notation/path-non-param-qself.stderr
+++ b/tests/ui/associated-type-bounds/return-type-notation/path-non-param-qself.stderr
@@ -3,18 +3,35 @@ error[E0223]: ambiguous associated function
    |
 LL |     <()>::method(..): Send,
    |     ^^^^^^^^^^^^^^^^
+   |
+help: if there were a trait named `Example` with associated function `method` implemented for `()`, you could use the fully-qualified path
+   |
+LL |     <() as Example>::method(..): Send,
+   |         ++++++++++
 
 error[E0223]: ambiguous associated function
   --> $DIR/path-non-param-qself.rs:13:5
    |
 LL |     i32::method(..): Send,
    |     ^^^^^^^^^^^^^^^
+   |
+help: if there were a trait named `Example` with associated function `method` implemented for `i32`, you could use the fully-qualified path
+   |
+LL -     i32::method(..): Send,
+LL +     <i32 as Example>::method(..): Send,
+   |
 
 error[E0223]: ambiguous associated function
   --> $DIR/path-non-param-qself.rs:15:5
    |
 LL |     Adt::method(..): Send,
    |     ^^^^^^^^^^^^^^^
+   |
+help: if there were a trait named `Example` with associated function `method` implemented for `Adt`, you could use the fully-qualified path
+   |
+LL -     Adt::method(..): Send,
+LL +     <Adt as Example>::method(..): Send,
+   |
 
 error: aborting due to 3 previous errors
 
diff --git a/tests/ui/associated-types/associated-types-in-ambiguous-context.stderr b/tests/ui/associated-types/associated-types-in-ambiguous-context.stderr
index 1be8db5ddf4..a7647cf26aa 100644
--- a/tests/ui/associated-types/associated-types-in-ambiguous-context.stderr
+++ b/tests/ui/associated-types/associated-types-in-ambiguous-context.stderr
@@ -14,7 +14,13 @@ error[E0223]: ambiguous associated type
   --> $DIR/associated-types-in-ambiguous-context.rs:22:17
    |
 LL | trait Foo where Foo::Assoc: Bar {
-   |                 ^^^^^^^^^^ help: use fully-qualified syntax: `<Self as Foo>::Assoc`
+   |                 ^^^^^^^^^^
+   |
+help: use fully-qualified syntax
+   |
+LL - trait Foo where Foo::Assoc: Bar {
+LL + trait Foo where <Self as Foo>::Assoc: Bar {
+   |
 
 error[E0223]: ambiguous associated type
   --> $DIR/associated-types-in-ambiguous-context.rs:27:10
@@ -42,7 +48,13 @@ error[E0223]: ambiguous associated type
   --> $DIR/associated-types-in-ambiguous-context.rs:13:23
    |
 LL |     fn grab(&self) -> Grab::Value;
-   |                       ^^^^^^^^^^^ help: use fully-qualified syntax: `<Self as Grab>::Value`
+   |                       ^^^^^^^^^^^
+   |
+help: use fully-qualified syntax
+   |
+LL -     fn grab(&self) -> Grab::Value;
+LL +     fn grab(&self) -> <Self as Grab>::Value;
+   |
 
 error[E0223]: ambiguous associated type
   --> $DIR/associated-types-in-ambiguous-context.rs:16:22
diff --git a/tests/ui/async-await/async-closures/async-fn-mut-impl-fn-once.rs b/tests/ui/async-await/async-closures/async-fn-mut-impl-fn-once.rs
new file mode 100644
index 00000000000..59d034953d7
--- /dev/null
+++ b/tests/ui/async-await/async-closures/async-fn-mut-impl-fn-once.rs
@@ -0,0 +1,15 @@
+//@ edition:2021
+//@ check-pass
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
+
+fn call_once<F>(_: impl FnOnce() -> F) {}
+
+fn main() {
+    let mut i = 0;
+    let c = async || {
+        i += 1;
+    };
+    call_once(c);
+}
diff --git a/tests/ui/async-await/async-drop/open-drop-error2.rs b/tests/ui/async-await/async-drop/open-drop-error2.rs
new file mode 100644
index 00000000000..b2a7b68190e
--- /dev/null
+++ b/tests/ui/async-await/async-drop/open-drop-error2.rs
@@ -0,0 +1,21 @@
+//@compile-flags: -Zvalidate-mir -Zinline-mir=yes --crate-type=lib
+
+#![feature(async_drop)]
+#![allow(incomplete_features)]
+
+use std::{
+    future::{Future, async_drop_in_place},
+    pin::pin,
+    task::Context,
+};
+
+fn wrong() -> impl Sized {
+    //~^ ERROR: the size for values of type `str` cannot be known at compilation time
+    *"abc" // Doesn't implement Sized
+}
+fn weird(context: &mut Context<'_>) {
+    let mut e = wrong();
+    let h = unsafe { async_drop_in_place(&raw mut e) };
+    let i = pin!(h);
+    i.poll(context);
+}
diff --git a/tests/ui/async-await/async-drop/open-drop-error2.stderr b/tests/ui/async-await/async-drop/open-drop-error2.stderr
new file mode 100644
index 00000000000..e849829b1c7
--- /dev/null
+++ b/tests/ui/async-await/async-drop/open-drop-error2.stderr
@@ -0,0 +1,19 @@
+error[E0277]: the size for values of type `str` cannot be known at compilation time
+  --> $DIR/open-drop-error2.rs:12:15
+   |
+LL | fn wrong() -> impl Sized {
+   |               ^^^^^^^^^^ doesn't have a size known at compile-time
+LL |
+LL |     *"abc" // Doesn't implement Sized
+   |     ------ return type was inferred to be `str` here
+   |
+   = help: the trait `Sized` is not implemented for `str`
+help: references are always `Sized`, even if they point to unsized data; consider not dereferencing the expression
+   |
+LL -     *"abc" // Doesn't implement Sized
+LL +     "abc" // Doesn't implement Sized
+   |
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/async-await/dyn/mut-is-pointer-like.stderr b/tests/ui/async-await/dyn/mut-is-pointer-like.stderr
index bf20473924b..07c3fd3527f 100644
--- a/tests/ui/async-await/dyn/mut-is-pointer-like.stderr
+++ b/tests/ui/async-await/dyn/mut-is-pointer-like.stderr
@@ -42,30 +42,6 @@ LL |     async fn async_dispatch(self: Pin<&mut Self>) -> Self::Output;
    = help: consider moving `async_dispatch` to another trait
    = note: required for the cast from `Pin<&mut {async block@$DIR/mut-is-pointer-like.rs:32:32: 32:37}>` to `Pin<&mut dyn AsyncTrait<Output = ()>>`
 
-error[E0277]: the trait bound `dyn AsyncTrait<Output = ()>: AsyncTrait` is not satisfied
-  --> $DIR/mut-is-pointer-like.rs:36:11
-   |
-LL |         x.async_dispatch().await;
-   |           ^^^^^^^^^^^^^^ the trait `AsyncTrait` is not implemented for `dyn AsyncTrait<Output = ()>`
-
-error[E0038]: the trait `AsyncTrait` is not dyn compatible
-  --> $DIR/mut-is-pointer-like.rs:36:9
-   |
-LL |         x.async_dispatch().await;
-   |         ^^^^^^^^^^^^^^^^^^ `AsyncTrait` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/mut-is-pointer-like.rs:16:14
-   |
-LL | trait AsyncTrait {
-   |       ---------- this trait is not dyn compatible...
-...
-LL |     async fn async_dispatch(self: Pin<&mut Self>) -> Self::Output;
-   |              ^^^^^^^^^^^^^^ ...because method `async_dispatch` is `async`
-   = help: consider moving `async_dispatch` to another trait
-
-error: aborting due to 4 previous errors; 1 warning emitted
+error: aborting due to 2 previous errors; 1 warning emitted
 
-Some errors have detailed explanations: E0038, E0277.
-For more information about an error, try `rustc --explain E0038`.
+For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/async-await/dyn/works.stderr b/tests/ui/async-await/dyn/works.stderr
index 47abeab5aac..1fe2b28eca8 100644
--- a/tests/ui/async-await/dyn/works.stderr
+++ b/tests/ui/async-await/dyn/works.stderr
@@ -42,40 +42,6 @@ LL |     async fn async_dispatch(&self);
    = help: consider moving `async_dispatch` to another trait
    = help: only type `&'static str` implements `AsyncTrait`; consider using it directly instead.
 
-error[E0038]: the trait `AsyncTrait` is not dyn compatible
-  --> $DIR/works.rs:28:11
-   |
-LL |         x.async_dispatch().await;
-   |           ^^^^^^^^^^^^^^ `AsyncTrait` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/works.rs:14:14
-   |
-LL | trait AsyncTrait {
-   |       ---------- this trait is not dyn compatible...
-LL |     async fn async_dispatch(&self);
-   |              ^^^^^^^^^^^^^^ ...because method `async_dispatch` is `async`
-   = help: consider moving `async_dispatch` to another trait
-   = help: only type `&'static str` implements `AsyncTrait`; consider using it directly instead.
-
-error[E0038]: the trait `AsyncTrait` is not dyn compatible
-  --> $DIR/works.rs:28:9
-   |
-LL |         x.async_dispatch().await;
-   |         ^^^^^^^^^^^^^^^^^^ `AsyncTrait` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/works.rs:14:14
-   |
-LL | trait AsyncTrait {
-   |       ---------- this trait is not dyn compatible...
-LL |     async fn async_dispatch(&self);
-   |              ^^^^^^^^^^^^^^ ...because method `async_dispatch` is `async`
-   = help: consider moving `async_dispatch` to another trait
-   = help: only type `&'static str` implements `AsyncTrait`; consider using it directly instead.
-
-error: aborting due to 4 previous errors; 1 warning emitted
+error: aborting due to 2 previous errors; 1 warning emitted
 
 For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/borrowck/unconstrained-closure-lifetime-generic.rs b/tests/ui/borrowck/unconstrained-closure-lifetime-generic.rs
new file mode 100644
index 00000000000..4fdf5470fea
--- /dev/null
+++ b/tests/ui/borrowck/unconstrained-closure-lifetime-generic.rs
@@ -0,0 +1,22 @@
+// Regression test for #122704
+use std::any::Any;
+
+pub struct Foo {
+    bar: Box<dyn for<'a> Fn(&'a usize) -> Box<dyn Any + 'a>>,
+}
+
+impl Foo {
+    pub fn ack<I>(&mut self, f: impl for<'a> Fn(&'a usize) -> Box<I>) {
+        self.bar = Box::new(|baz| Box::new(f(baz)));
+        //~^ ERROR the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` may not live long enough
+        //~| ERROR the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` may not live long enough
+        //~| ERROR the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` may not live long enough
+        //~| ERROR the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` may not live long enough
+        //~| ERROR the parameter type `I` may not live long enough
+        //~| ERROR the parameter type `I` may not live long enough
+        //~| ERROR the parameter type `I` may not live long enough
+        //~| ERROR `f` does not live long enough
+    }
+}
+
+fn main() {}
diff --git a/tests/ui/borrowck/unconstrained-closure-lifetime-generic.stderr b/tests/ui/borrowck/unconstrained-closure-lifetime-generic.stderr
new file mode 100644
index 00000000000..df86ce79f09
--- /dev/null
+++ b/tests/ui/borrowck/unconstrained-closure-lifetime-generic.stderr
@@ -0,0 +1,119 @@
+error[E0310]: the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` may not live long enough
+  --> $DIR/unconstrained-closure-lifetime-generic.rs:10:9
+   |
+LL |         self.bar = Box::new(|baz| Box::new(f(baz)));
+   |         ^^^^^^^^
+   |         |
+   |         the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` must be valid for the static lifetime...
+   |         ...so that the type `impl for<'a> Fn(&'a usize) -> Box<I>` will meet its required lifetime bounds
+   |
+help: consider adding an explicit lifetime bound
+   |
+LL |     pub fn ack<I>(&mut self, f: impl for<'a> Fn(&'a usize) -> Box<I> + 'static) {
+   |                                                                      +++++++++
+
+error[E0310]: the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` may not live long enough
+  --> $DIR/unconstrained-closure-lifetime-generic.rs:10:9
+   |
+LL |         self.bar = Box::new(|baz| Box::new(f(baz)));
+   |         ^^^^^^^^
+   |         |
+   |         the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` must be valid for the static lifetime...
+   |         ...so that the type `impl for<'a> Fn(&'a usize) -> Box<I>` will meet its required lifetime bounds
+   |
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+help: consider adding an explicit lifetime bound
+   |
+LL |     pub fn ack<I>(&mut self, f: impl for<'a> Fn(&'a usize) -> Box<I> + 'static) {
+   |                                                                      +++++++++
+
+error[E0310]: the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` may not live long enough
+  --> $DIR/unconstrained-closure-lifetime-generic.rs:10:20
+   |
+LL |         self.bar = Box::new(|baz| Box::new(f(baz)));
+   |                    ^^^^^^^^
+   |                    |
+   |                    the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` must be valid for the static lifetime...
+   |                    ...so that the type `impl for<'a> Fn(&'a usize) -> Box<I>` will meet its required lifetime bounds
+   |
+help: consider adding an explicit lifetime bound
+   |
+LL |     pub fn ack<I>(&mut self, f: impl for<'a> Fn(&'a usize) -> Box<I> + 'static) {
+   |                                                                      +++++++++
+
+error[E0310]: the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` may not live long enough
+  --> $DIR/unconstrained-closure-lifetime-generic.rs:10:20
+   |
+LL |         self.bar = Box::new(|baz| Box::new(f(baz)));
+   |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                    |
+   |                    the parameter type `impl for<'a> Fn(&'a usize) -> Box<I>` must be valid for the static lifetime...
+   |                    ...so that the type `impl for<'a> Fn(&'a usize) -> Box<I>` will meet its required lifetime bounds
+   |
+help: consider adding an explicit lifetime bound
+   |
+LL |     pub fn ack<I>(&mut self, f: impl for<'a> Fn(&'a usize) -> Box<I> + 'static) {
+   |                                                                      +++++++++
+
+error[E0310]: the parameter type `I` may not live long enough
+  --> $DIR/unconstrained-closure-lifetime-generic.rs:10:35
+   |
+LL |         self.bar = Box::new(|baz| Box::new(f(baz)));
+   |                                   ^^^^^^^^^^^^^^^^
+   |                                   |
+   |                                   the parameter type `I` must be valid for the static lifetime...
+   |                                   ...so that the type `I` will meet its required lifetime bounds
+   |
+help: consider adding an explicit lifetime bound
+   |
+LL |     pub fn ack<I: 'static>(&mut self, f: impl for<'a> Fn(&'a usize) -> Box<I>) {
+   |                 +++++++++
+
+error[E0310]: the parameter type `I` may not live long enough
+  --> $DIR/unconstrained-closure-lifetime-generic.rs:10:35
+   |
+LL |         self.bar = Box::new(|baz| Box::new(f(baz)));
+   |                                   ^^^^^^^^^^^^^^^^
+   |                                   |
+   |                                   the parameter type `I` must be valid for the static lifetime...
+   |                                   ...so that the type `I` will meet its required lifetime bounds
+   |
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+help: consider adding an explicit lifetime bound
+   |
+LL |     pub fn ack<I: 'static>(&mut self, f: impl for<'a> Fn(&'a usize) -> Box<I>) {
+   |                 +++++++++
+
+error[E0311]: the parameter type `I` may not live long enough
+  --> $DIR/unconstrained-closure-lifetime-generic.rs:10:35
+   |
+LL |     pub fn ack<I>(&mut self, f: impl for<'a> Fn(&'a usize) -> Box<I>) {
+   |                   --------- the parameter type `I` must be valid for the anonymous lifetime defined here...
+LL |         self.bar = Box::new(|baz| Box::new(f(baz)));
+   |                                   ^^^^^^^^^^^^^^^^ ...so that the type `I` will meet its required lifetime bounds
+   |
+help: consider adding an explicit lifetime bound
+   |
+LL |     pub fn ack<'a, I: 'a>(&'a mut self, f: impl for<'a> Fn(&'a usize) -> Box<I>) {
+   |                +++  ++++   ++
+
+error[E0597]: `f` does not live long enough
+  --> $DIR/unconstrained-closure-lifetime-generic.rs:10:44
+   |
+LL |     pub fn ack<I>(&mut self, f: impl for<'a> Fn(&'a usize) -> Box<I>) {
+   |                              - binding `f` declared here
+LL |         self.bar = Box::new(|baz| Box::new(f(baz)));
+   |         --------            -----          ^ borrowed value does not live long enough
+   |         |                   |
+   |         |                   value captured here
+   |         coercion requires that `f` is borrowed for `'static`
+...
+LL |     }
+   |     - `f` dropped here while still borrowed
+   |
+   = note: due to object lifetime defaults, `Box<dyn for<'a> Fn(&'a usize) -> Box<(dyn Any + 'a)>>` actually means `Box<(dyn for<'a> Fn(&'a usize) -> Box<(dyn Any + 'a)> + 'static)>`
+
+error: aborting due to 8 previous errors
+
+Some errors have detailed explanations: E0310, E0311, E0597.
+For more information about an error, try `rustc --explain E0310`.
diff --git a/tests/ui/borrowck/unconstrained-closure-lifetime-trait-object.rs b/tests/ui/borrowck/unconstrained-closure-lifetime-trait-object.rs
new file mode 100644
index 00000000000..3eee98d9bdb
--- /dev/null
+++ b/tests/ui/borrowck/unconstrained-closure-lifetime-trait-object.rs
@@ -0,0 +1,11 @@
+// Regression test for #139004
+use std::any::Any;
+
+type B = Box<dyn for<'a> Fn(&(dyn Any + 'a)) -> Box<dyn Any + 'a>>;
+
+fn foo<E>() -> B {
+    Box::new(|e| Box::new(e.is::<E>()))
+    //~^ ERROR the parameter type `E` may not live long enough
+}
+
+fn main() {}
diff --git a/tests/ui/borrowck/unconstrained-closure-lifetime-trait-object.stderr b/tests/ui/borrowck/unconstrained-closure-lifetime-trait-object.stderr
new file mode 100644
index 00000000000..c9d5f78828d
--- /dev/null
+++ b/tests/ui/borrowck/unconstrained-closure-lifetime-trait-object.stderr
@@ -0,0 +1,17 @@
+error[E0310]: the parameter type `E` may not live long enough
+  --> $DIR/unconstrained-closure-lifetime-trait-object.rs:7:29
+   |
+LL |     Box::new(|e| Box::new(e.is::<E>()))
+   |                             ^^
+   |                             |
+   |                             the parameter type `E` must be valid for the static lifetime...
+   |                             ...so that the type `E` will meet its required lifetime bounds
+   |
+help: consider adding an explicit lifetime bound
+   |
+LL | fn foo<E: 'static>() -> B {
+   |         +++++++++
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0310`.
diff --git a/tests/ui/check-cfg/wrong-version-syntax.fixed b/tests/ui/check-cfg/wrong-version-syntax.fixed
new file mode 100644
index 00000000000..efbe2ed1bd8
--- /dev/null
+++ b/tests/ui/check-cfg/wrong-version-syntax.fixed
@@ -0,0 +1,14 @@
+// Check warning for wrong `cfg(version("1.27"))` syntax
+//
+//@ check-pass
+//@ no-auto-check-cfg
+//@ compile-flags: --check-cfg=cfg()
+//@ run-rustfix
+
+#![feature(cfg_version)]
+
+#[cfg(not(version("1.48.0")))]
+//~^ WARNING unexpected `cfg` condition name: `version`
+pub fn g() {}
+
+pub fn main() {}
diff --git a/tests/ui/check-cfg/wrong-version-syntax.rs b/tests/ui/check-cfg/wrong-version-syntax.rs
new file mode 100644
index 00000000000..221ecf4cae8
--- /dev/null
+++ b/tests/ui/check-cfg/wrong-version-syntax.rs
@@ -0,0 +1,14 @@
+// Check warning for wrong `cfg(version("1.27"))` syntax
+//
+//@ check-pass
+//@ no-auto-check-cfg
+//@ compile-flags: --check-cfg=cfg()
+//@ run-rustfix
+
+#![feature(cfg_version)]
+
+#[cfg(not(version = "1.48.0"))]
+//~^ WARNING unexpected `cfg` condition name: `version`
+pub fn g() {}
+
+pub fn main() {}
diff --git a/tests/ui/check-cfg/wrong-version-syntax.stderr b/tests/ui/check-cfg/wrong-version-syntax.stderr
new file mode 100644
index 00000000000..97157a0c02b
--- /dev/null
+++ b/tests/ui/check-cfg/wrong-version-syntax.stderr
@@ -0,0 +1,17 @@
+warning: unexpected `cfg` condition name: `version`
+  --> $DIR/wrong-version-syntax.rs:10:11
+   |
+LL | #[cfg(not(version = "1.48.0"))]
+   |           ^^^^^^^^^^^^^^^^^^
+   |
+   = help: to expect this configuration use `--check-cfg=cfg(version, values("1.48.0"))`
+   = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration
+   = note: `#[warn(unexpected_cfgs)]` on by default
+help: there is a similar config predicate: `version("..")`
+   |
+LL - #[cfg(not(version = "1.48.0"))]
+LL + #[cfg(not(version("1.48.0")))]
+   |
+
+warning: 1 warning emitted
+
diff --git a/tests/ui/const-generics/associated_const_equality/equality_bound_with_infer.rs b/tests/ui/const-generics/associated_const_equality/equality_bound_with_infer.rs
new file mode 100644
index 00000000000..f45b7c3268b
--- /dev/null
+++ b/tests/ui/const-generics/associated_const_equality/equality_bound_with_infer.rs
@@ -0,0 +1,24 @@
+#![feature(generic_arg_infer, associated_const_equality, generic_const_items)]
+#![expect(incomplete_features)]
+
+// Regression test for #133066 where we would try to evaluate `<() as Foo>::ASSOC<_>` even
+// though it contained inference variables, which would cause ICEs.
+
+trait Foo {
+    const ASSOC<const N: u32>: u32;
+}
+
+impl Foo for () {
+    const ASSOC<const N: u32>: u32 = N;
+}
+
+fn bar<const N: u32, T: Foo<ASSOC<N> = 10>>() {}
+
+fn main() {
+    bar::<_, ()>();
+    //~^ ERROR: type mismatch resolving `<() as Foo>::ASSOC<_> == 10`
+
+    // FIXME(mgca):
+    // FIXME(associated_const_equality):
+    // This ought to start compiling once const items are aliases rather than bodies
+}
diff --git a/tests/ui/const-generics/associated_const_equality/equality_bound_with_infer.stderr b/tests/ui/const-generics/associated_const_equality/equality_bound_with_infer.stderr
new file mode 100644
index 00000000000..00741c901e4
--- /dev/null
+++ b/tests/ui/const-generics/associated_const_equality/equality_bound_with_infer.stderr
@@ -0,0 +1,17 @@
+error[E0271]: type mismatch resolving `<() as Foo>::ASSOC<_> == 10`
+  --> $DIR/equality_bound_with_infer.rs:18:14
+   |
+LL |     bar::<_, ()>();
+   |              ^^ expected `10`, found `<() as Foo>::ASSOC::<_>`
+   |
+   = note: expected constant `10`
+              found constant `<() as Foo>::ASSOC::<_>`
+note: required by a bound in `bar`
+  --> $DIR/equality_bound_with_infer.rs:15:29
+   |
+LL | fn bar<const N: u32, T: Foo<ASSOC<N> = 10>>() {}
+   |                             ^^^^^^^^^^^^^ required by this bound in `bar`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0271`.
diff --git a/tests/ui/const-generics/associated_const_equality/unconstrained_impl_param.rs b/tests/ui/const-generics/associated_const_equality/unconstrained_impl_param.rs
new file mode 100644
index 00000000000..99318ef7598
--- /dev/null
+++ b/tests/ui/const-generics/associated_const_equality/unconstrained_impl_param.rs
@@ -0,0 +1,26 @@
+// regression test for #137813 where we would assume all constants in the type system
+// cannot contain inference variables, even though associated const equality syntax
+// was still lowered without the feature gate enabled.
+
+trait AssocConst {
+    const A: u8;
+}
+
+impl<T> AssocConst for (T,) {
+    const A: u8 = 0;
+}
+
+trait Trait {}
+
+impl<U> Trait for () where (U,): AssocConst<A = { 0 }> {}
+//~^ ERROR associated const equality is incomplete
+//~| ERROR the type parameter `U` is not constrained by the impl trait
+
+fn foo()
+where
+    (): Trait,
+    //~^ ERROR type mismatch resolving
+{
+}
+
+fn main() {}
diff --git a/tests/ui/const-generics/associated_const_equality/unconstrained_impl_param.stderr b/tests/ui/const-generics/associated_const_equality/unconstrained_impl_param.stderr
new file mode 100644
index 00000000000..e6799ec5c3a
--- /dev/null
+++ b/tests/ui/const-generics/associated_const_equality/unconstrained_impl_param.stderr
@@ -0,0 +1,39 @@
+error[E0658]: associated const equality is incomplete
+  --> $DIR/unconstrained_impl_param.rs:15:45
+   |
+LL | impl<U> Trait for () where (U,): AssocConst<A = { 0 }> {}
+   |                                             ^^^^^^^^^
+   |
+   = note: see issue #92827 <https://github.com/rust-lang/rust/issues/92827> for more information
+   = help: add `#![feature(associated_const_equality)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+error[E0207]: the type parameter `U` is not constrained by the impl trait, self type, or predicates
+  --> $DIR/unconstrained_impl_param.rs:15:6
+   |
+LL | impl<U> Trait for () where (U,): AssocConst<A = { 0 }> {}
+   |      ^ unconstrained type parameter
+
+error[E0271]: type mismatch resolving `<(_,) as AssocConst>::A == 0`
+  --> $DIR/unconstrained_impl_param.rs:21:5
+   |
+LL |     (): Trait,
+   |     ^^^^^^^^^ expected `0`, found `<(_,) as AssocConst>::A`
+   |
+   = note: expected constant `0`
+              found constant `<(_,) as AssocConst>::A`
+note: required for `()` to implement `Trait`
+  --> $DIR/unconstrained_impl_param.rs:15:9
+   |
+LL | impl<U> Trait for () where (U,): AssocConst<A = { 0 }> {}
+   |         ^^^^^     ^^                        --------- unsatisfied trait bound introduced here
+   = help: see issue #48214
+help: add `#![feature(trivial_bounds)]` to the crate attributes to enable
+   |
+LL + #![feature(trivial_bounds)]
+   |
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0207, E0271, E0658.
+For more information about an error, try `rustc --explain E0207`.
diff --git a/tests/crashes/auxiliary/aux133199.rs b/tests/ui/const-generics/generic_const_exprs/auxiliary/cross-crate-2.rs
index 40765d92fbf..a8bda14f4bd 100644
--- a/tests/crashes/auxiliary/aux133199.rs
+++ b/tests/ui/const-generics/generic_const_exprs/auxiliary/cross-crate-2.rs
@@ -1,9 +1,9 @@
 #![allow(incomplete_features)]
 #![feature(generic_const_exprs)]
 
-pub struct FixedBitSet<const N: usize>;
+pub struct Foo<const N: usize>;
 
-impl<const N: usize> FixedBitSet<N>
+impl<const N: usize> Foo<N>
 where
     [u8; N.div_ceil(8)]: Sized,
 {
diff --git a/tests/ui/const-generics/generic_const_exprs/cross-crate-2.rs b/tests/ui/const-generics/generic_const_exprs/cross-crate-2.rs
new file mode 100644
index 00000000000..77998c7ec0a
--- /dev/null
+++ b/tests/ui/const-generics/generic_const_exprs/cross-crate-2.rs
@@ -0,0 +1,10 @@
+//@ check-pass
+//@ aux-build: cross-crate-2.rs
+
+extern crate cross_crate_2;
+
+use cross_crate_2::Foo;
+
+fn main() {
+    Foo::<7>::new();
+}
diff --git a/tests/ui/const-generics/generic_const_exprs/dependence_lint.full.stderr b/tests/ui/const-generics/generic_const_exprs/dependence_lint.full.stderr
index f454ff4e6c0..6b095f3818a 100644
--- a/tests/ui/const-generics/generic_const_exprs/dependence_lint.full.stderr
+++ b/tests/ui/const-generics/generic_const_exprs/dependence_lint.full.stderr
@@ -1,5 +1,5 @@
 error: generic parameters may not be used in const operations
-  --> $DIR/dependence_lint.rs:14:32
+  --> $DIR/dependence_lint.rs:15:32
    |
 LL |     let _: [u8; size_of::<*mut T>()]; // error on stable, error with gce
    |                                ^ cannot perform const operation using `T`
@@ -8,7 +8,7 @@ LL |     let _: [u8; size_of::<*mut T>()]; // error on stable, error with gce
    = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/dependence_lint.rs:21:37
+  --> $DIR/dependence_lint.rs:22:37
    |
 LL |     let _: [u8; if true { size_of::<T>() } else { 3 }]; // error on stable, error with gce
    |                                     ^ cannot perform const operation using `T`
@@ -27,7 +27,7 @@ LL |     [0; size_of::<*mut T>()]; // lint on stable, error with `generic_const_
    = note: `#[warn(const_evaluatable_unchecked)]` on by default
 
 warning: cannot use constants which depend on generic parameters in types
-  --> $DIR/dependence_lint.rs:17:9
+  --> $DIR/dependence_lint.rs:18:9
    |
 LL |     [0; if false { size_of::<T>() } else { 3 }]; // lint on stable, error with gce
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/tests/ui/const-generics/generic_const_exprs/dependence_lint.gce.stderr b/tests/ui/const-generics/generic_const_exprs/dependence_lint.gce.stderr
index f6119c17bf4..12ac980c975 100644
--- a/tests/ui/const-generics/generic_const_exprs/dependence_lint.gce.stderr
+++ b/tests/ui/const-generics/generic_const_exprs/dependence_lint.gce.stderr
@@ -9,8 +9,19 @@ help: try adding a `where` bound
 LL | fn foo<T>() where [(); size_of::<*mut T>()]: {
    |             ++++++++++++++++++++++++++++++++
 
+error: unconstrained generic constant
+  --> $DIR/dependence_lint.rs:10:5
+   |
+LL |     [0; size_of::<*mut T>()]; // lint on stable, error with `generic_const_exprs`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try adding a `where` bound
+   |
+LL | fn foo<T>() where [(); size_of::<*mut T>()]: {
+   |             ++++++++++++++++++++++++++++++++
+
 error: overly complex generic constant
-  --> $DIR/dependence_lint.rs:17:9
+  --> $DIR/dependence_lint.rs:18:9
    |
 LL |     [0; if false { size_of::<T>() } else { 3 }]; // lint on stable, error with gce
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ control flow is not supported in generic constants
@@ -18,7 +29,7 @@ LL |     [0; if false { size_of::<T>() } else { 3 }]; // lint on stable, error w
    = help: consider moving this anonymous constant into a `const` function
 
 error: unconstrained generic constant
-  --> $DIR/dependence_lint.rs:14:12
+  --> $DIR/dependence_lint.rs:15:12
    |
 LL |     let _: [u8; size_of::<*mut T>()]; // error on stable, error with gce
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -29,12 +40,12 @@ LL | fn foo<T>() where [(); size_of::<*mut T>()]: {
    |             ++++++++++++++++++++++++++++++++
 
 error: overly complex generic constant
-  --> $DIR/dependence_lint.rs:21:17
+  --> $DIR/dependence_lint.rs:22:17
    |
 LL |     let _: [u8; if true { size_of::<T>() } else { 3 }]; // error on stable, error with gce
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ control flow is not supported in generic constants
    |
    = help: consider moving this anonymous constant into a `const` function
 
-error: aborting due to 4 previous errors
+error: aborting due to 5 previous errors
 
diff --git a/tests/ui/const-generics/generic_const_exprs/dependence_lint.rs b/tests/ui/const-generics/generic_const_exprs/dependence_lint.rs
index 107466cd1d9..6b3c8f84be3 100644
--- a/tests/ui/const-generics/generic_const_exprs/dependence_lint.rs
+++ b/tests/ui/const-generics/generic_const_exprs/dependence_lint.rs
@@ -9,7 +9,8 @@ use std::mem::size_of;
 fn foo<T>() {
     [0; size_of::<*mut T>()]; // lint on stable, error with `generic_const_exprs`
     //[gce]~^ ERROR unconstrained
-    //[full]~^^ WARNING cannot use constants
+    //[gce]~| ERROR unconstrained generic constant
+    //[full]~^^^ WARNING cannot use constants
     //[full]~| WARNING this was previously accepted
     let _: [u8; size_of::<*mut T>()]; // error on stable, error with gce
     //[full]~^ ERROR generic parameters may not be used
diff --git a/tests/ui/const-generics/generic_const_exprs/different-fn.stderr b/tests/ui/const-generics/generic_const_exprs/different-fn.stderr
index ac80463480d..52917df0da1 100644
--- a/tests/ui/const-generics/generic_const_exprs/different-fn.stderr
+++ b/tests/ui/const-generics/generic_const_exprs/different-fn.stderr
@@ -2,10 +2,10 @@ error[E0308]: mismatched types
   --> $DIR/different-fn.rs:10:5
    |
 LL |     [0; size_of::<Foo<T>>()]
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^ expected `size_of::<T>()`, found `0`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^ expected `size_of::<T>()`, found `size_of::<Foo<T>>()`
    |
    = note: expected constant `size_of::<T>()`
-              found constant `0`
+              found constant `size_of::<Foo<T>>()`
 
 error: unconstrained generic constant
   --> $DIR/different-fn.rs:10:9
diff --git a/tests/ui/const-generics/generic_const_exprs/dyn-compatibility-err-ret.rs b/tests/ui/const-generics/generic_const_exprs/dyn-compatibility-err-ret.rs
index 9ab715d01f7..da9a75b50ef 100644
--- a/tests/ui/const-generics/generic_const_exprs/dyn-compatibility-err-ret.rs
+++ b/tests/ui/const-generics/generic_const_exprs/dyn-compatibility-err-ret.rs
@@ -15,7 +15,7 @@ impl Foo for () {
 }
 
 fn use_dyn(v: &dyn Foo) { //~ERROR the trait `Foo` is not dyn compatible
-    v.test(); //~ERROR the trait `Foo` is not dyn compatible
+    v.test();
 }
 
 fn main() {}
diff --git a/tests/ui/const-generics/generic_const_exprs/dyn-compatibility-err-ret.stderr b/tests/ui/const-generics/generic_const_exprs/dyn-compatibility-err-ret.stderr
index 8bc6ef093d0..120ee435e25 100644
--- a/tests/ui/const-generics/generic_const_exprs/dyn-compatibility-err-ret.stderr
+++ b/tests/ui/const-generics/generic_const_exprs/dyn-compatibility-err-ret.stderr
@@ -17,25 +17,6 @@ LL |     fn test(&self) -> [u8; bar::<Self>()];
    = help: consider moving `test` to another trait
    = help: only type `()` implements `Foo`; consider using it directly instead.
 
-error[E0038]: the trait `Foo` is not dyn compatible
-  --> $DIR/dyn-compatibility-err-ret.rs:18:5
-   |
-LL |     v.test();
-   |     ^^^^^^^^ `Foo` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/dyn-compatibility-err-ret.rs:8:8
-   |
-LL | trait Foo {
-   |       --- this trait is not dyn compatible...
-LL |     fn test(&self) -> [u8; bar::<Self>()];
-   |        ^^^^           ^^^^^^^^^^^^^^^^^^^ ...because method `test` references the `Self` type in its return type
-   |        |
-   |        ...because method `test` references the `Self` type in its `where` clause
-   = help: consider moving `test` to another trait
-   = help: only type `()` implements `Foo`; consider using it directly instead.
-
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/const-generics/generic_const_exprs/dyn-compatibility-err-where-bounds.rs b/tests/ui/const-generics/generic_const_exprs/dyn-compatibility-err-where-bounds.rs
index a7b771cd4f8..8b735188f32 100644
--- a/tests/ui/const-generics/generic_const_exprs/dyn-compatibility-err-where-bounds.rs
+++ b/tests/ui/const-generics/generic_const_exprs/dyn-compatibility-err-where-bounds.rs
@@ -15,7 +15,6 @@ impl Foo for () {
 fn use_dyn(v: &dyn Foo) {
     //~^ ERROR the trait `Foo` is not dyn compatible
     v.test();
-    //~^ ERROR the trait `Foo` is not dyn compatible
 }
 
 fn main() {}
diff --git a/tests/ui/const-generics/generic_const_exprs/dyn-compatibility-err-where-bounds.stderr b/tests/ui/const-generics/generic_const_exprs/dyn-compatibility-err-where-bounds.stderr
index f5eaaa37916..c2ad4d14988 100644
--- a/tests/ui/const-generics/generic_const_exprs/dyn-compatibility-err-where-bounds.stderr
+++ b/tests/ui/const-generics/generic_const_exprs/dyn-compatibility-err-where-bounds.stderr
@@ -15,23 +15,6 @@ LL |     fn test(&self) where [u8; bar::<Self>()]: Sized;
    = help: consider moving `test` to another trait
    = help: only type `()` implements `Foo`; consider using it directly instead.
 
-error[E0038]: the trait `Foo` is not dyn compatible
-  --> $DIR/dyn-compatibility-err-where-bounds.rs:17:5
-   |
-LL |     v.test();
-   |     ^^^^^^^^ `Foo` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/dyn-compatibility-err-where-bounds.rs:8:8
-   |
-LL | trait Foo {
-   |       --- this trait is not dyn compatible...
-LL |     fn test(&self) where [u8; bar::<Self>()]: Sized;
-   |        ^^^^ ...because method `test` references the `Self` type in its `where` clause
-   = help: consider moving `test` to another trait
-   = help: only type `()` implements `Foo`; consider using it directly instead.
-
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/const-generics/generic_const_exprs/serializing_error_guaranteed.rs b/tests/ui/const-generics/generic_const_exprs/serializing_error_guaranteed.rs
new file mode 100644
index 00000000000..83b73350f83
--- /dev/null
+++ b/tests/ui/const-generics/generic_const_exprs/serializing_error_guaranteed.rs
@@ -0,0 +1,16 @@
+//@ check-pass
+
+// regression test for #136894.
+// I (BoxyUwU) don't know what the underlying cause was here
+
+#![feature(generic_const_exprs)]
+#![crate_type = "lib"]
+#![allow(incomplete_features, dead_code)]
+
+struct X<T>([(); f::<T>()])
+where
+    [(); f::<T>()]:;
+
+const fn f<T>() -> usize {
+    panic!()
+}
diff --git a/tests/ui/const-generics/issues/issue-71202.rs b/tests/ui/const-generics/issues/issue-71202.rs
index 0f955414d84..8ff49b55e6f 100644
--- a/tests/ui/const-generics/issues/issue-71202.rs
+++ b/tests/ui/const-generics/issues/issue-71202.rs
@@ -25,7 +25,9 @@ impl<T: Copy> DataHolder<T> {
         }
 
         <IsCopy<T>>::VALUE
-    } as usize] = []; //~ ERROR unconstrained generic constant
+    } as usize] = [];
+    //~^ ERROR unconstrained generic constant
+    //~^^ ERROR mismatched types
 }
 
 fn main() {}
diff --git a/tests/ui/const-generics/issues/issue-71202.stderr b/tests/ui/const-generics/issues/issue-71202.stderr
index cc3603d1145..b7c3db494a5 100644
--- a/tests/ui/const-generics/issues/issue-71202.stderr
+++ b/tests/ui/const-generics/issues/issue-71202.stderr
@@ -59,5 +59,49 @@ LL +         <IsCopy<T>>::VALUE
 LL ~     } as usize]: = [];
    |
 
-error: aborting due to 2 previous errors
+error[E0308]: mismatched types
+  --> $DIR/issue-71202.rs:28:19
+   |
+LL |     } as usize] = [];
+   |                   ^^ expected `1 - {
+        trait NotCopy {
+            const VALUE: bool = false;
+        }
+
+        impl<__Type: ?Sized> NotCopy for __Type {}
+
+        struct IsCopy<__Type: ?Sized>(PhantomData<__Type>);
+
+        impl<__Type> IsCopy<__Type>
+        where
+            __Type: Sized + Copy,
+        {
+            const VALUE: bool = true;
+        }
+
+        <IsCopy<T>>::VALUE
+    } as usize`, found `0`
+   |
+   = note: expected constant `1 - {
+                   trait NotCopy {
+                       const VALUE: bool = false;
+                   }
+           
+                   impl<__Type: ?Sized> NotCopy for __Type {}
+           
+                   struct IsCopy<__Type: ?Sized>(PhantomData<__Type>);
+           
+                   impl<__Type> IsCopy<__Type>
+                   where
+                       __Type: Sized + Copy,
+                   {
+                       const VALUE: bool = true;
+                   }
+           
+                   <IsCopy<T>>::VALUE
+               } as usize`
+              found constant `0`
+
+error: aborting due to 3 previous errors
 
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/const-generics/issues/issue-83765.rs b/tests/ui/const-generics/issues/issue-83765.rs
index 0959f771c22..f31c61408e9 100644
--- a/tests/ui/const-generics/issues/issue-83765.rs
+++ b/tests/ui/const-generics/issues/issue-83765.rs
@@ -3,10 +3,6 @@
 
 trait TensorDimension {
     const DIM: usize;
-    //~^ ERROR cycle detected when resolving instance
-    //~| ERROR cycle detected when resolving instance
-    // FIXME Given the current state of the compiler its expected that we cycle here,
-    // but the cycle is still wrong.
     const ISSCALAR: bool = Self::DIM == 0;
     fn is_scalar(&self) -> bool {
         Self::ISSCALAR
@@ -49,6 +45,7 @@ impl<'a, T: Broadcastable, const DIM: usize> TensorDimension for LazyUpdim<'a, T
 
 impl<'a, T: Broadcastable, const DIM: usize> TensorSize for LazyUpdim<'a, T, { T::DIM }, DIM> {
     fn size(&self) -> [usize; DIM] {
+        //~^ ERROR: method not compatible with trait
         self.size
     }
 }
@@ -56,12 +53,17 @@ impl<'a, T: Broadcastable, const DIM: usize> TensorSize for LazyUpdim<'a, T, { T
 impl<'a, T: Broadcastable, const DIM: usize> Broadcastable for LazyUpdim<'a, T, { T::DIM }, DIM> {
     type Element = T::Element;
     fn bget(&self, index: [usize; DIM]) -> Option<Self::Element> {
+        //~^ ERROR: method not compatible with trait
         assert!(DIM >= T::DIM);
         if !self.inbounds(index) {
+            //~^ ERROR: unconstrained generic constant
+            //~| ERROR: mismatched types
             return None;
         }
         let size = self.size();
+        //~^ ERROR: unconstrained generic constant
         let newindex: [usize; T::DIM] = Default::default();
+        //~^ ERROR: the trait bound
         self.reference.bget(newindex)
     }
 }
@@ -82,6 +84,8 @@ impl<'a, R, T: Broadcastable, F: Fn(T::Element) -> R, const DIM: usize> TensorSi
     fn size(&self) -> [usize; DIM] {
         //~^ ERROR: method not compatible with trait
         self.reference.size()
+        //~^ ERROR: unconstrained generic constant
+        //~| ERROR: mismatched types
     }
 }
 
@@ -92,6 +96,8 @@ impl<'a, R, T: Broadcastable, F: Fn(T::Element) -> R, const DIM: usize> Broadcas
     fn bget(&self, index: [usize; DIM]) -> Option<Self::Element> {
         //~^ ERROR: method not compatible with trait
         self.reference.bget(index).map(&self.closure)
+        //~^ ERROR: unconstrained generic constant
+        //~| ERROR: mismatched types
     }
 }
 
@@ -100,12 +106,14 @@ impl<T> TensorDimension for Vec<T> {
 }
 impl<T> TensorSize for Vec<T> {
     fn size(&self) -> [usize; 1] {
+        //~^ ERROR: method not compatible with trait
         [self.len()]
     }
 }
 impl<T: Clone> Broadcastable for Vec<T> {
     type Element = T;
     fn bget(&self, index: [usize; 1]) -> Option<T> {
+        //~^ ERROR: method not compatible with trait
         self.get(index[0]).cloned()
     }
 }
diff --git a/tests/ui/const-generics/issues/issue-83765.stderr b/tests/ui/const-generics/issues/issue-83765.stderr
index 6b62012c14f..5a06ee7ddbc 100644
--- a/tests/ui/const-generics/issues/issue-83765.stderr
+++ b/tests/ui/const-generics/issues/issue-83765.stderr
@@ -1,43 +1,23 @@
-error[E0391]: cycle detected when resolving instance `<LazyUpdim<'_, T, <T as TensorDimension>::DIM, DIM> as TensorDimension>::DIM`
-  --> $DIR/issue-83765.rs:5:5
-   |
-LL |     const DIM: usize;
-   |     ^^^^^^^^^^^^^^^^
-   |
-note: ...which requires computing candidate for `<LazyUpdim<'_, T, <T as TensorDimension>::DIM, DIM> as TensorDimension>`...
-  --> $DIR/issue-83765.rs:4:1
-   |
-LL | trait TensorDimension {
-   | ^^^^^^^^^^^^^^^^^^^^^
-   = note: ...which again requires resolving instance `<LazyUpdim<'_, T, <T as TensorDimension>::DIM, DIM> as TensorDimension>::DIM`, completing the cycle
-note: cycle used when checking assoc item `<impl at $DIR/issue-83765.rs:50:1: 50:94>::size` is compatible with trait definition
-  --> $DIR/issue-83765.rs:51:5
+error[E0308]: method not compatible with trait
+  --> $DIR/issue-83765.rs:47:5
    |
 LL |     fn size(&self) -> [usize; DIM] {
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
-
-error[E0391]: cycle detected when resolving instance `<LazyUpdim<'_, T, <T as TensorDimension>::DIM, DIM> as TensorDimension>::DIM`
-  --> $DIR/issue-83765.rs:5:5
-   |
-LL |     const DIM: usize;
-   |     ^^^^^^^^^^^^^^^^
-   |
-note: ...which requires computing candidate for `<LazyUpdim<'_, T, <T as TensorDimension>::DIM, DIM> as TensorDimension>`...
-  --> $DIR/issue-83765.rs:4:1
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `Self::DIM`, found `DIM`
    |
-LL | trait TensorDimension {
-   | ^^^^^^^^^^^^^^^^^^^^^
-   = note: ...which again requires resolving instance `<LazyUpdim<'_, T, <T as TensorDimension>::DIM, DIM> as TensorDimension>::DIM`, completing the cycle
-note: cycle used when checking assoc item `<impl at $DIR/issue-83765.rs:56:1: 56:97>::bget` is compatible with trait definition
-  --> $DIR/issue-83765.rs:58:5
+   = note: expected constant `Self::DIM`
+              found constant `DIM`
+
+error[E0308]: method not compatible with trait
+  --> $DIR/issue-83765.rs:55:5
    |
 LL |     fn bget(&self, index: [usize; DIM]) -> Option<Self::Element> {
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `Self::DIM`, found `DIM`
+   |
+   = note: expected constant `Self::DIM`
+              found constant `DIM`
 
 error[E0308]: method not compatible with trait
-  --> $DIR/issue-83765.rs:82:5
+  --> $DIR/issue-83765.rs:84:5
    |
 LL |     fn size(&self) -> [usize; DIM] {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `Self::DIM`, found `DIM`
@@ -46,7 +26,7 @@ LL |     fn size(&self) -> [usize; DIM] {
               found constant `DIM`
 
 error[E0308]: method not compatible with trait
-  --> $DIR/issue-83765.rs:92:5
+  --> $DIR/issue-83765.rs:96:5
    |
 LL |     fn bget(&self, index: [usize; DIM]) -> Option<Self::Element> {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `Self::DIM`, found `DIM`
@@ -54,7 +34,127 @@ LL |     fn bget(&self, index: [usize; DIM]) -> Option<Self::Element> {
    = note: expected constant `Self::DIM`
               found constant `DIM`
 
-error: aborting due to 4 previous errors
+error[E0308]: method not compatible with trait
+  --> $DIR/issue-83765.rs:108:5
+   |
+LL |     fn size(&self) -> [usize; 1] {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `Self::DIM`, found `1`
+   |
+   = note: expected constant `Self::DIM`
+              found constant `1`
+
+error[E0308]: method not compatible with trait
+  --> $DIR/issue-83765.rs:115:5
+   |
+LL |     fn bget(&self, index: [usize; 1]) -> Option<T> {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `Self::DIM`, found `1`
+   |
+   = note: expected constant `Self::DIM`
+              found constant `1`
+
+error: unconstrained generic constant
+  --> $DIR/issue-83765.rs:58:13
+   |
+LL |         if !self.inbounds(index) {
+   |             ^^^^
+   |
+note: required by a bound in `TensorSize::inbounds`
+  --> $DIR/issue-83765.rs:14:39
+   |
+LL |     fn inbounds(&self, index: [usize; Self::DIM]) -> bool {
+   |                                       ^^^^^^^^^ required by this bound in `TensorSize::inbounds`
+help: try adding a `where` bound
+   |
+LL |     fn bget(&self, index: [usize; DIM]) -> Option<Self::Element> where [(); Self::DIM]: {
+   |                                                                  ++++++++++++++++++++++
+
+error[E0308]: mismatched types
+  --> $DIR/issue-83765.rs:58:27
+   |
+LL |         if !self.inbounds(index) {
+   |                           ^^^^^ expected `Self::DIM`, found `DIM`
+   |
+   = note: expected constant `Self::DIM`
+              found constant `DIM`
+
+error: unconstrained generic constant
+  --> $DIR/issue-83765.rs:63:25
+   |
+LL |         let size = self.size();
+   |                         ^^^^
+   |
+note: required by a bound in `TensorSize::size`
+  --> $DIR/issue-83765.rs:13:31
+   |
+LL |     fn size(&self) -> [usize; Self::DIM];
+   |                               ^^^^^^^^^ required by this bound in `TensorSize::size`
+help: try adding a `where` bound
+   |
+LL |     fn bget(&self, index: [usize; DIM]) -> Option<Self::Element> where [(); Self::DIM]: {
+   |                                                                  ++++++++++++++++++++++
+
+error[E0277]: the trait bound `[usize; T::DIM]: Default` is not satisfied
+  --> $DIR/issue-83765.rs:65:41
+   |
+LL |         let newindex: [usize; T::DIM] = Default::default();
+   |                                         ^^^^^^^^^^^^^^^^^^ the trait `Default` is not implemented for `[usize; T::DIM]`
+   |
+help: consider introducing a `where` clause, but there might be an alternative better way to express this requirement
+   |
+LL | impl<'a, T: Broadcastable, const DIM: usize> Broadcastable for LazyUpdim<'a, T, { T::DIM }, DIM> where [usize; T::DIM]: Default {
+   |                                                                                                  ++++++++++++++++++++++++++++++
+
+error: unconstrained generic constant
+  --> $DIR/issue-83765.rs:86:24
+   |
+LL |         self.reference.size()
+   |                        ^^^^
+   |
+note: required by a bound in `TensorSize::size`
+  --> $DIR/issue-83765.rs:13:31
+   |
+LL |     fn size(&self) -> [usize; Self::DIM];
+   |                               ^^^^^^^^^ required by this bound in `TensorSize::size`
+help: try adding a `where` bound
+   |
+LL |     fn size(&self) -> [usize; DIM] where [(); Self::DIM]: {
+   |                                    ++++++++++++++++++++++
+
+error[E0308]: mismatched types
+  --> $DIR/issue-83765.rs:86:9
+   |
+LL |         self.reference.size()
+   |         ^^^^^^^^^^^^^^^^^^^^^ expected `DIM`, found `Self::DIM`
+   |
+   = note: expected constant `DIM`
+              found constant `Self::DIM`
+
+error: unconstrained generic constant
+  --> $DIR/issue-83765.rs:98:9
+   |
+LL |         self.reference.bget(index).map(&self.closure)
+   |         ^^^^^^^^^^^^^^
+   |
+note: required by a bound in `Broadcastable::bget`
+  --> $DIR/issue-83765.rs:21:35
+   |
+LL |     fn bget(&self, index: [usize; Self::DIM]) -> Option<Self::Element>;
+   |                                   ^^^^^^^^^ required by this bound in `Broadcastable::bget`
+help: try adding a `where` bound
+   |
+LL |     fn bget(&self, index: [usize; DIM]) -> Option<Self::Element> where [(); Self::DIM]: {
+   |                                                                  ++++++++++++++++++++++
+
+error[E0308]: mismatched types
+  --> $DIR/issue-83765.rs:98:29
+   |
+LL |         self.reference.bget(index).map(&self.closure)
+   |                             ^^^^^ expected `Self::DIM`, found `DIM`
+   |
+   = note: expected constant `Self::DIM`
+              found constant `DIM`
+
+error: aborting due to 14 previous errors
 
-Some errors have detailed explanations: E0308, E0391.
-For more information about an error, try `rustc --explain E0308`.
+Some errors have detailed explanations: E0277, E0308.
+For more information about an error, try `rustc --explain E0277`.
diff --git a/tests/ui/const-generics/mgca/projection-error.rs b/tests/ui/const-generics/mgca/projection-error.rs
new file mode 100644
index 00000000000..d1c4fa8a492
--- /dev/null
+++ b/tests/ui/const-generics/mgca/projection-error.rs
@@ -0,0 +1,17 @@
+#![feature(min_generic_const_args)]
+#![expect(incomplete_features)]
+
+// Regression test for #140642. Test that normalizing const aliases
+// containing erroneous types normalizes to a const error instead of
+// a type error.
+
+
+pub trait Tr<A> {
+    const SIZE: usize;
+}
+
+fn mk_array(_x: T) -> [(); <T as Tr<bool>>::SIZE] {}
+//~^ ERROR: cannot find type `T` in this scope
+//~| ERROR: cannot find type `T` in this scope
+
+fn main() {}
diff --git a/tests/ui/const-generics/mgca/projection-error.stderr b/tests/ui/const-generics/mgca/projection-error.stderr
new file mode 100644
index 00000000000..e6888351da1
--- /dev/null
+++ b/tests/ui/const-generics/mgca/projection-error.stderr
@@ -0,0 +1,39 @@
+error[E0412]: cannot find type `T` in this scope
+  --> $DIR/projection-error.rs:13:17
+   |
+LL | pub trait Tr<A> {
+   | --------------- similarly named trait `Tr` defined here
+...
+LL | fn mk_array(_x: T) -> [(); <T as Tr<bool>>::SIZE] {}
+   |                 ^
+   |
+help: a trait with a similar name exists
+   |
+LL | fn mk_array(_x: Tr) -> [(); <T as Tr<bool>>::SIZE] {}
+   |                  +
+help: you might be missing a type parameter
+   |
+LL | fn mk_array<T>(_x: T) -> [(); <T as Tr<bool>>::SIZE] {}
+   |            +++
+
+error[E0412]: cannot find type `T` in this scope
+  --> $DIR/projection-error.rs:13:29
+   |
+LL | pub trait Tr<A> {
+   | --------------- similarly named trait `Tr` defined here
+...
+LL | fn mk_array(_x: T) -> [(); <T as Tr<bool>>::SIZE] {}
+   |                             ^
+   |
+help: a trait with a similar name exists
+   |
+LL | fn mk_array(_x: T) -> [(); <Tr as Tr<bool>>::SIZE] {}
+   |                              +
+help: you might be missing a type parameter
+   |
+LL | fn mk_array<T>(_x: T) -> [(); <T as Tr<bool>>::SIZE] {}
+   |            +++
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0412`.
diff --git a/tests/ui/diagnostic_namespace/on_unimplemented/do_not_accept_options_of_the_internal_rustc_attribute.rs b/tests/ui/diagnostic_namespace/on_unimplemented/do_not_accept_options_of_the_internal_rustc_attribute.rs
index b76b550fcb2..a0e497fa045 100644
--- a/tests/ui/diagnostic_namespace/on_unimplemented/do_not_accept_options_of_the_internal_rustc_attribute.rs
+++ b/tests/ui/diagnostic_namespace/on_unimplemented/do_not_accept_options_of_the_internal_rustc_attribute.rs
@@ -3,7 +3,7 @@
 //@ reference: attributes.diagnostic.on_unimplemented.syntax
 //@ reference: attributes.diagnostic.on_unimplemented.invalid-formats
 #[diagnostic::on_unimplemented(
-    on(_Self = "&str"),
+    on(Self = "&str"),
     //~^WARN malformed `on_unimplemented` attribute
     //~|WARN malformed `on_unimplemented` attribute
     message = "trait has `{Self}` and `{T}` as params",
@@ -41,7 +41,7 @@ impl Bar for i32 {}
     //~|WARN there is no parameter `integral` on trait `Baz`
     //~|WARN there is no parameter `integer` on trait `Baz`
     //~|WARN there is no parameter `integer` on trait `Baz`
-    label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
+    label = "{float}{_Self}{crate_local}{Trait}{ItemContext}{This}"
     //~^WARN there is no parameter `float` on trait `Baz`
     //~|WARN there is no parameter `float` on trait `Baz`
     //~|WARN there is no parameter `_Self` on trait `Baz`
@@ -52,6 +52,8 @@ impl Bar for i32 {}
     //~|WARN there is no parameter `Trait` on trait `Baz`
     //~|WARN there is no parameter `ItemContext` on trait `Baz`
     //~|WARN there is no parameter `ItemContext` on trait `Baz`
+    //~|WARN there is no parameter `This` on trait `Baz`
+    //~|WARN there is no parameter `This` on trait `Baz`
 )]
 trait Baz {}
 
diff --git a/tests/ui/diagnostic_namespace/on_unimplemented/do_not_accept_options_of_the_internal_rustc_attribute.stderr b/tests/ui/diagnostic_namespace/on_unimplemented/do_not_accept_options_of_the_internal_rustc_attribute.stderr
index 88816a98dcf..8dace7d9052 100644
--- a/tests/ui/diagnostic_namespace/on_unimplemented/do_not_accept_options_of_the_internal_rustc_attribute.stderr
+++ b/tests/ui/diagnostic_namespace/on_unimplemented/do_not_accept_options_of_the_internal_rustc_attribute.stderr
@@ -9,8 +9,8 @@ LL | #[diagnostic::on_unimplemented(message = "Not allowed to apply it on a impl
 warning: malformed `on_unimplemented` attribute
   --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:6:5
    |
-LL |     on(_Self = "&str"),
-   |     ^^^^^^^^^^^^^^^^^^ invalid option found here
+LL |     on(Self = "&str"),
+   |     ^^^^^^^^^^^^^^^^^ invalid option found here
    |
    = help: only `message`, `note` and `label` are allowed as options
 
@@ -81,7 +81,7 @@ LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
 warning: there is no parameter `float` on trait `Baz`
   --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:44:15
    |
-LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
+LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}{This}"
    |               ^^^^^
    |
    = help: expect either a generic argument name or `{Self}` as format argument
@@ -89,7 +89,7 @@ LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
 warning: there is no parameter `_Self` on trait `Baz`
   --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:44:22
    |
-LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
+LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}{This}"
    |                      ^^^^^
    |
    = help: expect either a generic argument name or `{Self}` as format argument
@@ -97,7 +97,7 @@ LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
 warning: there is no parameter `crate_local` on trait `Baz`
   --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:44:29
    |
-LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
+LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}{This}"
    |                             ^^^^^^^^^^^
    |
    = help: expect either a generic argument name or `{Self}` as format argument
@@ -105,7 +105,7 @@ LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
 warning: there is no parameter `Trait` on trait `Baz`
   --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:44:42
    |
-LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
+LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}{This}"
    |                                          ^^^^^
    |
    = help: expect either a generic argument name or `{Self}` as format argument
@@ -113,16 +113,24 @@ LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
 warning: there is no parameter `ItemContext` on trait `Baz`
   --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:44:49
    |
-LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
+LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}{This}"
    |                                                 ^^^^^^^^^^^
    |
    = help: expect either a generic argument name or `{Self}` as format argument
 
+warning: there is no parameter `This` on trait `Baz`
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:44:62
+   |
+LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}{This}"
+   |                                                              ^^^^
+   |
+   = help: expect either a generic argument name or `{Self}` as format argument
+
 warning: malformed `on_unimplemented` attribute
   --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:6:5
    |
-LL |     on(_Self = "&str"),
-   |     ^^^^^^^^^^^^^^^^^^ invalid option found here
+LL |     on(Self = "&str"),
+   |     ^^^^^^^^^^^^^^^^^ invalid option found here
    |
    = help: only `message`, `note` and `label` are allowed as options
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
@@ -146,7 +154,7 @@ LL |     append_const_msg
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error[E0277]: trait has `()` and `i32` as params
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:63:15
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:65:15
    |
 LL |     takes_foo(());
    |     --------- ^^ trait has `()` and `i32` as params
@@ -161,7 +169,7 @@ help: this trait has no implementations, consider adding one
 LL | trait Foo<T> {}
    | ^^^^^^^^^^^^
 note: required by a bound in `takes_foo`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:58:22
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:60:22
    |
 LL | fn takes_foo(_: impl Foo<i32>) {}
    |                      ^^^^^^^^ required by this bound in `takes_foo`
@@ -176,7 +184,7 @@ LL | #[diagnostic::on_unimplemented = "Message"]
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error[E0277]: the trait bound `(): Bar` is not satisfied
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:65:15
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:67:15
    |
 LL |     takes_bar(());
    |     --------- ^^ the trait `Bar` is not implemented for `()`
@@ -185,7 +193,7 @@ LL |     takes_bar(());
    |
    = help: the trait `Bar` is implemented for `i32`
 note: required by a bound in `takes_bar`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:59:22
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:61:22
    |
 LL | fn takes_bar(_: impl Bar) {}
    |                      ^^^ required by this bound in `takes_bar`
@@ -238,7 +246,7 @@ LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
 warning: there is no parameter `float` on trait `Baz`
   --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:44:15
    |
-LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
+LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}{This}"
    |               ^^^^^
    |
    = help: expect either a generic argument name or `{Self}` as format argument
@@ -247,7 +255,7 @@ LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
 warning: there is no parameter `_Self` on trait `Baz`
   --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:44:22
    |
-LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
+LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}{This}"
    |                      ^^^^^
    |
    = help: expect either a generic argument name or `{Self}` as format argument
@@ -256,7 +264,7 @@ LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
 warning: there is no parameter `crate_local` on trait `Baz`
   --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:44:29
    |
-LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
+LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}{This}"
    |                             ^^^^^^^^^^^
    |
    = help: expect either a generic argument name or `{Self}` as format argument
@@ -265,7 +273,7 @@ LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
 warning: there is no parameter `Trait` on trait `Baz`
   --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:44:42
    |
-LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
+LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}{This}"
    |                                          ^^^^^
    |
    = help: expect either a generic argument name or `{Self}` as format argument
@@ -274,32 +282,41 @@ LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
 warning: there is no parameter `ItemContext` on trait `Baz`
   --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:44:49
    |
-LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
+LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}{This}"
    |                                                 ^^^^^^^^^^^
    |
    = help: expect either a generic argument name or `{Self}` as format argument
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
+warning: there is no parameter `This` on trait `Baz`
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:44:62
+   |
+LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}{This}"
+   |                                                              ^^^^
+   |
+   = help: expect either a generic argument name or `{Self}` as format argument
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
 error[E0277]: {from_desugaring}{direct}{cause}{integral}{integer}
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:67:15
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:69:15
    |
 LL |     takes_baz(());
-   |     --------- ^^ {float}{_Self}{crate_local}{Trait}{ItemContext}
+   |     --------- ^^ {float}{_Self}{crate_local}{Trait}{ItemContext}{This}
    |     |
    |     required by a bound introduced by this call
    |
    = help: the trait `Baz` is not implemented for `()`
 help: this trait has no implementations, consider adding one
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:56:1
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:58:1
    |
 LL | trait Baz {}
    | ^^^^^^^^^
 note: required by a bound in `takes_baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:60:22
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:62:22
    |
 LL | fn takes_baz(_: impl Baz) {}
    |                      ^^^ required by this bound in `takes_baz`
 
-error: aborting due to 3 previous errors; 29 warnings emitted
+error: aborting due to 3 previous errors; 31 warnings emitted
 
 For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/diagnostic_namespace/on_unimplemented/do_not_fail_parsing_on_invalid_options_1.rs b/tests/ui/diagnostic_namespace/on_unimplemented/do_not_fail_parsing_on_invalid_options_1.rs
index 8328c10d2a0..08eb5707e90 100644
--- a/tests/ui/diagnostic_namespace/on_unimplemented/do_not_fail_parsing_on_invalid_options_1.rs
+++ b/tests/ui/diagnostic_namespace/on_unimplemented/do_not_fail_parsing_on_invalid_options_1.rs
@@ -14,11 +14,15 @@ struct Bar {}
 //~|WARN malformed `on_unimplemented` attribute
 trait Baz {}
 
-#[diagnostic::on_unimplemented(message = "Boom", on(_Self = "i32", message = "whatever"))]
+#[diagnostic::on_unimplemented(message = "Boom", on(Self = "i32", message = "whatever"))]
 //~^WARN malformed `on_unimplemented` attribute
 //~|WARN malformed `on_unimplemented` attribute
 trait Boom {}
 
+#[diagnostic::on_unimplemented(message = "Boom", on(_Self = "i32", message = "whatever"))]
+//~^WARN malformed `on_unimplemented` attribute
+trait _Self {}
+
 #[diagnostic::on_unimplemented = "boom"]
 //~^WARN malformed `on_unimplemented` attribute
 trait Doom {}
diff --git a/tests/ui/diagnostic_namespace/on_unimplemented/do_not_fail_parsing_on_invalid_options_1.stderr b/tests/ui/diagnostic_namespace/on_unimplemented/do_not_fail_parsing_on_invalid_options_1.stderr
index 4dd8c1afca0..80790dc3f79 100644
--- a/tests/ui/diagnostic_namespace/on_unimplemented/do_not_fail_parsing_on_invalid_options_1.stderr
+++ b/tests/ui/diagnostic_namespace/on_unimplemented/do_not_fail_parsing_on_invalid_options_1.stderr
@@ -25,13 +25,21 @@ LL | #[diagnostic::on_unimplemented(message = "Boom", unsupported = "Bar")]
 warning: malformed `on_unimplemented` attribute
   --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:17:50
    |
+LL | #[diagnostic::on_unimplemented(message = "Boom", on(Self = "i32", message = "whatever"))]
+   |                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ invalid option found here
+   |
+   = help: only `message`, `note` and `label` are allowed as options
+
+warning: malformed `on_unimplemented` attribute
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:22:50
+   |
 LL | #[diagnostic::on_unimplemented(message = "Boom", on(_Self = "i32", message = "whatever"))]
    |                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ invalid option found here
    |
    = help: only `message`, `note` and `label` are allowed as options
 
 warning: malformed `on_unimplemented` attribute
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:22:32
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:26:32
    |
 LL | #[diagnostic::on_unimplemented = "boom"]
    |                                ^^^^^^^^ invalid option found here
@@ -39,7 +47,7 @@ LL | #[diagnostic::on_unimplemented = "boom"]
    = help: only `message`, `note` and `label` are allowed as options
 
 warning: missing options for `on_unimplemented` attribute
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:26:1
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:30:1
    |
 LL | #[diagnostic::on_unimplemented]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -47,7 +55,7 @@ LL | #[diagnostic::on_unimplemented]
    = help: at least one of the `message`, `note` and `label` options are expected
 
 warning: there is no parameter `DoesNotExist` on trait `Test`
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:31:44
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:35:44
    |
 LL | #[diagnostic::on_unimplemented(message = "{DoesNotExist}")]
    |                                            ^^^^^^^^^^^^
@@ -64,7 +72,7 @@ LL | #[diagnostic::on_unimplemented(unsupported = "foo")]
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error[E0277]: the trait bound `i32: Foo` is not satisfied
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:43:14
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:47:14
    |
 LL |     take_foo(1_i32);
    |     -------- ^^^^^ the trait `Foo` is not implemented for `i32`
@@ -77,7 +85,7 @@ help: this trait has no implementations, consider adding one
 LL | trait Foo {}
    | ^^^^^^^^^
 note: required by a bound in `take_foo`
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:36:21
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:40:21
    |
 LL | fn take_foo(_: impl Foo) {}
    |                     ^^^ required by this bound in `take_foo`
@@ -92,7 +100,7 @@ LL | #[diagnostic::on_unimplemented(message = "Boom", unsupported = "Bar")]
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error[E0277]: Boom
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:45:14
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:49:14
    |
 LL |     take_baz(1_i32);
    |     -------- ^^^^^ the trait `Baz` is not implemented for `i32`
@@ -105,7 +113,7 @@ help: this trait has no implementations, consider adding one
 LL | trait Baz {}
    | ^^^^^^^^^
 note: required by a bound in `take_baz`
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:37:21
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:41:21
    |
 LL | fn take_baz(_: impl Baz) {}
    |                     ^^^ required by this bound in `take_baz`
@@ -113,14 +121,14 @@ LL | fn take_baz(_: impl Baz) {}
 warning: malformed `on_unimplemented` attribute
   --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:17:50
    |
-LL | #[diagnostic::on_unimplemented(message = "Boom", on(_Self = "i32", message = "whatever"))]
-   |                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ invalid option found here
+LL | #[diagnostic::on_unimplemented(message = "Boom", on(Self = "i32", message = "whatever"))]
+   |                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ invalid option found here
    |
    = help: only `message`, `note` and `label` are allowed as options
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error[E0277]: Boom
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:47:15
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:51:15
    |
 LL |     take_boom(1_i32);
    |     --------- ^^^^^ the trait `Boom` is not implemented for `i32`
@@ -133,13 +141,13 @@ help: this trait has no implementations, consider adding one
 LL | trait Boom {}
    | ^^^^^^^^^^
 note: required by a bound in `take_boom`
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:38:22
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:42:22
    |
 LL | fn take_boom(_: impl Boom) {}
    |                      ^^^^ required by this bound in `take_boom`
 
 warning: missing options for `on_unimplemented` attribute
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:26:1
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:30:1
    |
 LL | #[diagnostic::on_unimplemented]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -148,7 +156,7 @@ LL | #[diagnostic::on_unimplemented]
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error[E0277]: the trait bound `i32: Whatever` is not satisfied
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:49:19
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:53:19
    |
 LL |     take_whatever(1_i32);
    |     ------------- ^^^^^ the trait `Whatever` is not implemented for `i32`
@@ -156,18 +164,18 @@ LL |     take_whatever(1_i32);
    |     required by a bound introduced by this call
    |
 help: this trait has no implementations, consider adding one
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:29:1
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:33:1
    |
 LL | trait Whatever {}
    | ^^^^^^^^^^^^^^
 note: required by a bound in `take_whatever`
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:39:26
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:43:26
    |
 LL | fn take_whatever(_: impl Whatever) {}
    |                          ^^^^^^^^ required by this bound in `take_whatever`
 
 warning: there is no parameter `DoesNotExist` on trait `Test`
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:31:44
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:35:44
    |
 LL | #[diagnostic::on_unimplemented(message = "{DoesNotExist}")]
    |                                            ^^^^^^^^^^^^
@@ -176,7 +184,7 @@ LL | #[diagnostic::on_unimplemented(message = "{DoesNotExist}")]
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error[E0277]: {DoesNotExist}
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:51:15
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:55:15
    |
 LL |     take_test(());
    |     --------- ^^ the trait `Test` is not implemented for `()`
@@ -184,16 +192,16 @@ LL |     take_test(());
    |     required by a bound introduced by this call
    |
 help: this trait has no implementations, consider adding one
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:34:1
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:38:1
    |
 LL | trait Test {}
    | ^^^^^^^^^^
 note: required by a bound in `take_test`
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:40:22
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:44:22
    |
 LL | fn take_test(_: impl Test) {}
    |                      ^^^^ required by this bound in `take_test`
 
-error: aborting due to 5 previous errors; 12 warnings emitted
+error: aborting due to 5 previous errors; 13 warnings emitted
 
 For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/dyn-compatibility/undispatchable-receiver-and-wc-references-Self.rs b/tests/ui/dyn-compatibility/undispatchable-receiver-and-wc-references-Self.rs
index ec32bec7785..ac3c2aadf29 100644
--- a/tests/ui/dyn-compatibility/undispatchable-receiver-and-wc-references-Self.rs
+++ b/tests/ui/dyn-compatibility/undispatchable-receiver-and-wc-references-Self.rs
@@ -25,5 +25,4 @@ pub fn foo() {
     let fetcher = fetcher();
     //~^ ERROR the trait `Fetcher` is not dyn compatible
     let _ = fetcher.get();
-    //~^ ERROR the trait `Fetcher` is not dyn compatible
 }
diff --git a/tests/ui/dyn-compatibility/undispatchable-receiver-and-wc-references-Self.stderr b/tests/ui/dyn-compatibility/undispatchable-receiver-and-wc-references-Self.stderr
index 1299167159e..867a719e2eb 100644
--- a/tests/ui/dyn-compatibility/undispatchable-receiver-and-wc-references-Self.stderr
+++ b/tests/ui/dyn-compatibility/undispatchable-receiver-and-wc-references-Self.stderr
@@ -34,24 +34,6 @@ LL | pub trait Fetcher: Send + Sync {
 LL |     fn get<'a>(self: &'a Box<Self>) -> Pin<Box<dyn Future<Output = Vec<u8>> + 'a>>
    |                      ^^^^^^^^^^^^^ ...because method `get`'s `self` parameter cannot be dispatched on
 
-error[E0038]: the trait `Fetcher` is not dyn compatible
-  --> $DIR/undispatchable-receiver-and-wc-references-Self.rs:27:13
-   |
-LL |     fn get<'a>(self: &'a Box<Self>) -> Pin<Box<dyn Future<Output = Vec<u8>> + 'a>>
-   |                      ------------- help: consider changing method `get`'s `self` parameter to be `&self`: `&Self`
-...
-LL |     let _ = fetcher.get();
-   |             ^^^^^^^^^^^^^ `Fetcher` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/undispatchable-receiver-and-wc-references-Self.rs:11:22
-   |
-LL | pub trait Fetcher: Send + Sync {
-   |           ------- this trait is not dyn compatible...
-LL |     fn get<'a>(self: &'a Box<Self>) -> Pin<Box<dyn Future<Output = Vec<u8>> + 'a>>
-   |                      ^^^^^^^^^^^^^ ...because method `get`'s `self` parameter cannot be dispatched on
-
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/error-codes/E0038.rs b/tests/ui/error-codes/E0038.rs
index a467767c3fa..9757e2ab10c 100644
--- a/tests/ui/error-codes/E0038.rs
+++ b/tests/ui/error-codes/E0038.rs
@@ -5,8 +5,6 @@ trait Trait {
 fn call_foo(x: Box<dyn Trait>) {
     //~^ ERROR E0038
     let y = x.foo();
-    //~^ ERROR E0038
-    //~| ERROR E0277
 }
 
 fn main() {
diff --git a/tests/ui/error-codes/E0038.stderr b/tests/ui/error-codes/E0038.stderr
index 63a5249a386..e09aefaa0dd 100644
--- a/tests/ui/error-codes/E0038.stderr
+++ b/tests/ui/error-codes/E0038.stderr
@@ -14,33 +14,6 @@ LL |     fn foo(&self) -> Self;
    |                      ^^^^ ...because method `foo` references the `Self` type in its return type
    = help: consider moving `foo` to another trait
 
-error[E0038]: the trait `Trait` is not dyn compatible
-  --> $DIR/E0038.rs:7:13
-   |
-LL |     let y = x.foo();
-   |             ^^^^^^^ `Trait` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/E0038.rs:2:22
-   |
-LL | trait Trait {
-   |       ----- this trait is not dyn compatible...
-LL |     fn foo(&self) -> Self;
-   |                      ^^^^ ...because method `foo` references the `Self` type in its return type
-   = help: consider moving `foo` to another trait
-
-error[E0277]: the size for values of type `dyn Trait` cannot be known at compilation time
-  --> $DIR/E0038.rs:7:9
-   |
-LL |     let y = x.foo();
-   |         ^ doesn't have a size known at compile-time
-   |
-   = help: the trait `Sized` is not implemented for `dyn Trait`
-   = note: all local variables must have a statically known size
-   = help: unsized locals are gated as an unstable feature
-
-error: aborting due to 3 previous errors
+error: aborting due to 1 previous error
 
-Some errors have detailed explanations: E0038, E0277.
-For more information about an error, try `rustc --explain E0038`.
+For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/error-codes/E0223.stderr b/tests/ui/error-codes/E0223.stderr
index e985a4c9bf0..fbfdce5689a 100644
--- a/tests/ui/error-codes/E0223.stderr
+++ b/tests/ui/error-codes/E0223.stderr
@@ -2,7 +2,13 @@ error[E0223]: ambiguous associated type
   --> $DIR/E0223.rs:8:14
    |
 LL |     let foo: MyTrait::X;
-   |              ^^^^^^^^^^ help: use fully-qualified syntax: `<MyStruct as MyTrait>::X`
+   |              ^^^^^^^^^^
+   |
+help: use fully-qualified syntax
+   |
+LL -     let foo: MyTrait::X;
+LL +     let foo: <MyStruct as MyTrait>::X;
+   |
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/feature-gates/feature-gate-async-fn-in-dyn-trait.rs b/tests/ui/feature-gates/feature-gate-async-fn-in-dyn-trait.rs
index 278a5451e84..50e5fd1ab7a 100644
--- a/tests/ui/feature-gates/feature-gate-async-fn-in-dyn-trait.rs
+++ b/tests/ui/feature-gates/feature-gate-async-fn-in-dyn-trait.rs
@@ -7,8 +7,6 @@ trait Foo {
 async fn takes_dyn_trait(x: &dyn Foo) {
     //~^ ERROR the trait `Foo` is not dyn compatible
     x.bar().await;
-    //~^ ERROR the trait `Foo` is not dyn compatible
-    //~| ERROR the trait `Foo` is not dyn compatible
 }
 
 fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-async-fn-in-dyn-trait.stderr b/tests/ui/feature-gates/feature-gate-async-fn-in-dyn-trait.stderr
index ab8c092a826..fd94b0babdb 100644
--- a/tests/ui/feature-gates/feature-gate-async-fn-in-dyn-trait.stderr
+++ b/tests/ui/feature-gates/feature-gate-async-fn-in-dyn-trait.stderr
@@ -14,38 +14,6 @@ LL |     async fn bar(&self);
    |              ^^^ ...because method `bar` is `async`
    = help: consider moving `bar` to another trait
 
-error[E0038]: the trait `Foo` is not dyn compatible
-  --> $DIR/feature-gate-async-fn-in-dyn-trait.rs:9:7
-   |
-LL |     x.bar().await;
-   |       ^^^ `Foo` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/feature-gate-async-fn-in-dyn-trait.rs:4:14
-   |
-LL | trait Foo {
-   |       --- this trait is not dyn compatible...
-LL |     async fn bar(&self);
-   |              ^^^ ...because method `bar` is `async`
-   = help: consider moving `bar` to another trait
-
-error[E0038]: the trait `Foo` is not dyn compatible
-  --> $DIR/feature-gate-async-fn-in-dyn-trait.rs:9:5
-   |
-LL |     x.bar().await;
-   |     ^^^^^^^ `Foo` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/feature-gate-async-fn-in-dyn-trait.rs:4:14
-   |
-LL | trait Foo {
-   |       --- this trait is not dyn compatible...
-LL |     async fn bar(&self);
-   |              ^^^ ...because method `bar` is `async`
-   = help: consider moving `bar` to another trait
-
-error: aborting due to 3 previous errors
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/generic-associated-types/trait-objects.rs b/tests/ui/generic-associated-types/trait-objects.rs
index 256cfee4c80..87817111b54 100644
--- a/tests/ui/generic-associated-types/trait-objects.rs
+++ b/tests/ui/generic-associated-types/trait-objects.rs
@@ -8,8 +8,6 @@ trait StreamingIterator {
 fn min_size(x: &mut dyn for<'a> StreamingIterator<Item<'a> = &'a i32>) -> usize {
     //~^ ERROR the trait `StreamingIterator` is not dyn compatible
     x.size_hint().0
-    //~^ ERROR the trait `StreamingIterator` is not dyn compatible
-    //~| ERROR the trait `StreamingIterator` is not dyn compatible
 }
 
 fn main() {}
diff --git a/tests/ui/generic-associated-types/trait-objects.stderr b/tests/ui/generic-associated-types/trait-objects.stderr
index 7d95718ec87..8c3af6b654a 100644
--- a/tests/ui/generic-associated-types/trait-objects.stderr
+++ b/tests/ui/generic-associated-types/trait-objects.stderr
@@ -14,38 +14,6 @@ LL |     type Item<'a> where Self: 'a;
    |          ^^^^ ...because it contains the generic associated type `Item`
    = help: consider moving `Item` to another trait
 
-error[E0038]: the trait `StreamingIterator` is not dyn compatible
-  --> $DIR/trait-objects.rs:10:7
-   |
-LL |     x.size_hint().0
-   |       ^^^^^^^^^ `StreamingIterator` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/trait-objects.rs:2:10
-   |
-LL | trait StreamingIterator {
-   |       ----------------- this trait is not dyn compatible...
-LL |     type Item<'a> where Self: 'a;
-   |          ^^^^ ...because it contains the generic associated type `Item`
-   = help: consider moving `Item` to another trait
-
-error[E0038]: the trait `StreamingIterator` is not dyn compatible
-  --> $DIR/trait-objects.rs:10:5
-   |
-LL |     x.size_hint().0
-   |     ^^^^^^^^^^^^^ `StreamingIterator` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/trait-objects.rs:2:10
-   |
-LL | trait StreamingIterator {
-   |       ----------------- this trait is not dyn compatible...
-LL |     type Item<'a> where Self: 'a;
-   |          ^^^^ ...because it contains the generic associated type `Item`
-   = help: consider moving `Item` to another trait
-
-error: aborting due to 3 previous errors
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/impl-trait/in-trait/dyn-compatibility.rs b/tests/ui/impl-trait/in-trait/dyn-compatibility.rs
index 85b1ba269fc..92203c470bb 100644
--- a/tests/ui/impl-trait/in-trait/dyn-compatibility.rs
+++ b/tests/ui/impl-trait/in-trait/dyn-compatibility.rs
@@ -15,6 +15,4 @@ fn main() {
     //~^ ERROR the trait `Foo` is not dyn compatible
     //~| ERROR the trait `Foo` is not dyn compatible
     let s = i.baz();
-    //~^ ERROR the trait `Foo` is not dyn compatible
-    //~| ERROR the trait `Foo` is not dyn compatible
 }
diff --git a/tests/ui/impl-trait/in-trait/dyn-compatibility.stderr b/tests/ui/impl-trait/in-trait/dyn-compatibility.stderr
index 840c27e183f..5c498548aff 100644
--- a/tests/ui/impl-trait/in-trait/dyn-compatibility.stderr
+++ b/tests/ui/impl-trait/in-trait/dyn-compatibility.stderr
@@ -16,40 +16,6 @@ LL |     fn baz(&self) -> impl Debug;
    = help: only type `u32` implements `Foo`; consider using it directly instead.
 
 error[E0038]: the trait `Foo` is not dyn compatible
-  --> $DIR/dyn-compatibility.rs:17:15
-   |
-LL |     let s = i.baz();
-   |               ^^^ `Foo` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/dyn-compatibility.rs:4:22
-   |
-LL | trait Foo {
-   |       --- this trait is not dyn compatible...
-LL |     fn baz(&self) -> impl Debug;
-   |                      ^^^^^^^^^^ ...because method `baz` references an `impl Trait` type in its return type
-   = help: consider moving `baz` to another trait
-   = help: only type `u32` implements `Foo`; consider using it directly instead.
-
-error[E0038]: the trait `Foo` is not dyn compatible
-  --> $DIR/dyn-compatibility.rs:17:13
-   |
-LL |     let s = i.baz();
-   |             ^^^^^^^ `Foo` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/dyn-compatibility.rs:4:22
-   |
-LL | trait Foo {
-   |       --- this trait is not dyn compatible...
-LL |     fn baz(&self) -> impl Debug;
-   |                      ^^^^^^^^^^ ...because method `baz` references an `impl Trait` type in its return type
-   = help: consider moving `baz` to another trait
-   = help: only type `u32` implements `Foo`; consider using it directly instead.
-
-error[E0038]: the trait `Foo` is not dyn compatible
   --> $DIR/dyn-compatibility.rs:14:13
    |
 LL |     let i = Box::new(42_u32) as Box<dyn Foo>;
@@ -67,6 +33,6 @@ LL |     fn baz(&self) -> impl Debug;
    = help: only type `u32` implements `Foo`; consider using it directly instead.
    = note: required for the cast from `Box<u32>` to `Box<dyn Foo>`
 
-error: aborting due to 4 previous errors
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/issues/issue-18959.rs b/tests/ui/issues/issue-18959.rs
index 6aeb34879ea..dbc73bafce9 100644
--- a/tests/ui/issues/issue-18959.rs
+++ b/tests/ui/issues/issue-18959.rs
@@ -11,7 +11,6 @@ impl Foo for Thing {
 fn foo(b: &dyn Bar) {
     //~^ ERROR E0038
     b.foo(&0)
-    //~^ ERROR E0038
 }
 
 fn main() {
diff --git a/tests/ui/issues/issue-18959.stderr b/tests/ui/issues/issue-18959.stderr
index 1e050b115e5..7ddfdb49d95 100644
--- a/tests/ui/issues/issue-18959.stderr
+++ b/tests/ui/issues/issue-18959.stderr
@@ -15,23 +15,7 @@ LL | pub trait Bar: Foo { }
    = help: consider moving `foo` to another trait
 
 error[E0038]: the trait `Bar` is not dyn compatible
-  --> $DIR/issue-18959.rs:13:5
-   |
-LL |     b.foo(&0)
-   |     ^^^^^^^^^ `Bar` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/issue-18959.rs:1:20
-   |
-LL | pub trait Foo { fn foo<T>(&self, ext_thing: &T); }
-   |                    ^^^ ...because method `foo` has generic type parameters
-LL | pub trait Bar: Foo { }
-   |           --- this trait is not dyn compatible...
-   = help: consider moving `foo` to another trait
-
-error[E0038]: the trait `Bar` is not dyn compatible
-  --> $DIR/issue-18959.rs:19:26
+  --> $DIR/issue-18959.rs:18:26
    |
 LL |     let test: &dyn Bar = &mut thing;
    |                          ^^^^^^^^^^ `Bar` is not dyn compatible
@@ -48,7 +32,7 @@ LL | pub trait Bar: Foo { }
    = note: required for the cast from `&mut Thing` to `&dyn Bar`
 
 error[E0038]: the trait `Bar` is not dyn compatible
-  --> $DIR/issue-18959.rs:19:15
+  --> $DIR/issue-18959.rs:18:15
    |
 LL |     let test: &dyn Bar = &mut thing;
    |               ^^^^^^^^ `Bar` is not dyn compatible
@@ -63,6 +47,6 @@ LL | pub trait Bar: Foo { }
    |           --- this trait is not dyn compatible...
    = help: consider moving `foo` to another trait
 
-error: aborting due to 4 previous errors
+error: aborting due to 3 previous errors
 
 For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/lang-items/lang-item-generic-requirements.rs b/tests/ui/lang-items/lang-item-generic-requirements.rs
index 90ed5f3f0ef..7676b5557d2 100644
--- a/tests/ui/lang-items/lang-item-generic-requirements.rs
+++ b/tests/ui/lang-items/lang-item-generic-requirements.rs
@@ -49,12 +49,14 @@ fn ice() {
     // Use index
     let arr = [0; 5];
     let _ = arr[2];
+    //~^ ERROR cannot index into a value of type `[{integer}; 5]`
 
     // Use phantomdata
     let _ = MyPhantomData::<(), i32>;
 
     // Use Foo
     let _: () = Foo;
+    //~^ ERROR mismatched types
 }
 
 // use `start`
diff --git a/tests/ui/lang-items/lang-item-generic-requirements.stderr b/tests/ui/lang-items/lang-item-generic-requirements.stderr
index 3de67d65940..409fa05d637 100644
--- a/tests/ui/lang-items/lang-item-generic-requirements.stderr
+++ b/tests/ui/lang-items/lang-item-generic-requirements.stderr
@@ -76,9 +76,23 @@ LL |     r + a;
    |     |
    |     {integer}
 
+error[E0608]: cannot index into a value of type `[{integer}; 5]`
+  --> $DIR/lang-item-generic-requirements.rs:51:16
+   |
+LL |     let _ = arr[2];
+   |                ^^^
+
+error[E0308]: mismatched types
+  --> $DIR/lang-item-generic-requirements.rs:58:17
+   |
+LL |     let _: () = Foo;
+   |            --   ^^^ expected `()`, found `Foo`
+   |            |
+   |            expected due to this
+
 error: requires `copy` lang_item
 
-error: aborting due to 10 previous errors
+error: aborting due to 12 previous errors
 
-Some errors have detailed explanations: E0369, E0392, E0718.
-For more information about an error, try `rustc --explain E0369`.
+Some errors have detailed explanations: E0308, E0369, E0392, E0608, E0718.
+For more information about an error, try `rustc --explain E0308`.
diff --git a/tests/ui/lint/bare-trait-objects-path.stderr b/tests/ui/lint/bare-trait-objects-path.stderr
index fbb647c37c5..e611abd31f3 100644
--- a/tests/ui/lint/bare-trait-objects-path.stderr
+++ b/tests/ui/lint/bare-trait-objects-path.stderr
@@ -55,7 +55,13 @@ error[E0223]: ambiguous associated type
   --> $DIR/bare-trait-objects-path.rs:23:12
    |
 LL |     let _: Dyn::Ty;
-   |            ^^^^^^^ help: use fully-qualified syntax: `<dyn Dyn as Assoc>::Ty`
+   |            ^^^^^^^
+   |
+help: use fully-qualified syntax
+   |
+LL -     let _: Dyn::Ty;
+LL +     let _: <dyn Dyn as Assoc>::Ty;
+   |
 
 error: aborting due to 1 previous error; 4 warnings emitted
 
diff --git a/tests/ui/mismatched_types/hr-projection-mismatch.current.stderr b/tests/ui/mismatched_types/hr-projection-mismatch.current.stderr
new file mode 100644
index 00000000000..a2cec972e4a
--- /dev/null
+++ b/tests/ui/mismatched_types/hr-projection-mismatch.current.stderr
@@ -0,0 +1,12 @@
+error[E0308]: mismatched types
+  --> $DIR/hr-projection-mismatch.rs:20:5
+   |
+LL |     wrap::<_, Thing>();
+   |     ^^^^^^^^^^^^^^^^ one type is more general than the other
+   |
+   = note: expected reference `&'a _`
+              found reference `&_`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/mismatched_types/hr-projection-mismatch.next.stderr b/tests/ui/mismatched_types/hr-projection-mismatch.next.stderr
new file mode 100644
index 00000000000..6ea0d43e153
--- /dev/null
+++ b/tests/ui/mismatched_types/hr-projection-mismatch.next.stderr
@@ -0,0 +1,20 @@
+error[E0271]: type mismatch resolving `<Thing as Trait<'a>>::Assoc == &i32`
+  --> $DIR/hr-projection-mismatch.rs:20:15
+   |
+LL |     wrap::<_, Thing>();
+   |               ^^^^^ type mismatch resolving `<Thing as Trait<'a>>::Assoc == &i32`
+   |
+note: types differ
+  --> $DIR/hr-projection-mismatch.rs:14:18
+   |
+LL |     type Assoc = &'a i32;
+   |                  ^^^^^^^
+note: required by a bound in `wrap`
+  --> $DIR/hr-projection-mismatch.rs:17:33
+   |
+LL | fn wrap<T, U: for<'a> Trait<'a, Assoc = T>>() {}
+   |                                 ^^^^^^^^^ required by this bound in `wrap`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0271`.
diff --git a/tests/ui/mismatched_types/hr-projection-mismatch.rs b/tests/ui/mismatched_types/hr-projection-mismatch.rs
new file mode 100644
index 00000000000..f96314a3fca
--- /dev/null
+++ b/tests/ui/mismatched_types/hr-projection-mismatch.rs
@@ -0,0 +1,25 @@
+//@ revisions: current next
+//@ ignore-compare-mode-next-solver (explicit revisions)
+//@[next] compile-flags: -Znext-solver
+
+// Regression test for <https://github.com/rust-lang/rust/issues/141322>.
+
+trait Trait<'a> {
+    type Assoc;
+}
+
+struct Thing;
+
+impl<'a> Trait<'a> for Thing {
+    type Assoc = &'a i32;
+}
+
+fn wrap<T, U: for<'a> Trait<'a, Assoc = T>>() {}
+
+fn foo() {
+    wrap::<_, Thing>();
+    //[next]~^ ERROR type mismatch resolving `<Thing as Trait<'a>>::Assoc == &i32
+    //[current]~^^ ERROR mismatched types
+}
+
+fn main() {}
diff --git a/tests/ui/on-unimplemented/bad-annotation.rs b/tests/ui/on-unimplemented/bad-annotation.rs
index 25de5978110..937e5b82da5 100644
--- a/tests/ui/on-unimplemented/bad-annotation.rs
+++ b/tests/ui/on-unimplemented/bad-annotation.rs
@@ -59,7 +59,7 @@ trait EmptyOn {}
 //~^^^ NOTE expected value here
 trait ExpectedPredicateInOn {}
 
-#[rustc_on_unimplemented(on(x = "y"), message = "y")]
+#[rustc_on_unimplemented(on(Self = "y"), message = "y")]
 trait OnWithoutDirectives {}
 
 #[rustc_on_unimplemented(on(from_desugaring, on(from_desugaring, message = "x")), message = "y")]
@@ -107,3 +107,13 @@ trait InvalidPredicate {}
 //~^ ERROR invalid flag in `on`-clause
 //~^^ NOTE expected one of the `crate_local`, `direct` or `from_desugaring` flags, not `something`
 trait InvalidFlag {}
+
+#[rustc_on_unimplemented(on(_Self = "y", message = "y"))]
+//~^ ERROR invalid name in `on`-clause
+//~^^ NOTE expected one of `cause`, `from_desugaring`, `Self` or any generic parameter of the trait, not `_Self`
+trait InvalidName {}
+
+#[rustc_on_unimplemented(on(abc = "y", message = "y"))]
+//~^ ERROR invalid name in `on`-clause
+//~^^ NOTE expected one of `cause`, `from_desugaring`, `Self` or any generic parameter of the trait, not `abc`
+trait InvalidName2 {}
diff --git a/tests/ui/on-unimplemented/bad-annotation.stderr b/tests/ui/on-unimplemented/bad-annotation.stderr
index 35b919c7b78..3fc54532774 100644
--- a/tests/ui/on-unimplemented/bad-annotation.stderr
+++ b/tests/ui/on-unimplemented/bad-annotation.stderr
@@ -125,7 +125,19 @@ error[E0232]: invalid flag in `on`-clause
 LL | #[rustc_on_unimplemented(on(something, message = "y"))]
    |                             ^^^^^^^^^ expected one of the `crate_local`, `direct` or `from_desugaring` flags, not `something`
 
-error: aborting due to 18 previous errors
+error[E0232]: invalid name in `on`-clause
+  --> $DIR/bad-annotation.rs:111:29
+   |
+LL | #[rustc_on_unimplemented(on(_Self = "y", message = "y"))]
+   |                             ^^^^^ expected one of `cause`, `from_desugaring`, `Self` or any generic parameter of the trait, not `_Self`
+
+error[E0232]: invalid name in `on`-clause
+  --> $DIR/bad-annotation.rs:116:29
+   |
+LL | #[rustc_on_unimplemented(on(abc = "y", message = "y"))]
+   |                             ^^^ expected one of `cause`, `from_desugaring`, `Self` or any generic parameter of the trait, not `abc`
+
+error: aborting due to 20 previous errors
 
 Some errors have detailed explanations: E0230, E0231, E0232.
 For more information about an error, try `rustc --explain E0230`.
diff --git a/tests/ui/on-unimplemented/on-trait.rs b/tests/ui/on-unimplemented/on-trait.rs
index 556813cd479..91630af17e9 100644
--- a/tests/ui/on-unimplemented/on-trait.rs
+++ b/tests/ui/on-unimplemented/on-trait.rs
@@ -3,7 +3,7 @@
 #![feature(rustc_attrs)]
 
 pub mod Bar {
-  #[rustc_on_unimplemented = "test error `{Self}` with `{Bar}` `{Baz}` `{Quux}` in `{Foo}`"]
+  #[rustc_on_unimplemented = "test error `{Self}` with `{Bar}` `{Baz}` `{Quux}` in `{This}`"]
   pub trait Foo<Bar, Baz, Quux> {}
 }
 
diff --git a/tests/ui/panics/location-detail-unwrap-multiline.rs b/tests/ui/panics/location-detail-unwrap-multiline.rs
new file mode 100644
index 00000000000..56e1760d851
--- /dev/null
+++ b/tests/ui/panics/location-detail-unwrap-multiline.rs
@@ -0,0 +1,12 @@
+//@ run-fail
+//@ compile-flags: -Cstrip=none -Cdebuginfo=line-tables-only -Copt-level=0
+//@ exec-env:RUST_BACKTRACE=1
+//@ regex-error-pattern: location-detail-unwrap-multiline\.rs:11(:10)?\n
+//@ needs-unwind
+//@ ignore-android FIXME #17520
+
+fn main() {
+    let opt: Option<u32> = None;
+    opt
+        .unwrap();
+}
diff --git a/tests/ui/pattern/unused-parameters-const-pattern.rs b/tests/ui/pattern/unused-parameters-const-pattern.rs
new file mode 100644
index 00000000000..107c65ddfd3
--- /dev/null
+++ b/tests/ui/pattern/unused-parameters-const-pattern.rs
@@ -0,0 +1,19 @@
+//@ check-pass
+
+// Tests that const patterns that use generic parameters are
+// allowed if we are still able to evaluate them.
+
+trait Trait { const ASSOC: usize; }
+
+impl<T> Trait for T {
+    const ASSOC: usize = 10;
+}
+
+fn foo<T>(a: usize) {
+    match a {
+        <T as Trait>::ASSOC => (),
+        _ => (),
+    }
+}
+
+fn main() {}
diff --git a/tests/ui/qualified/qualified-path-params-2.stderr b/tests/ui/qualified/qualified-path-params-2.stderr
index 6641e81013f..e70cdbdc3f4 100644
--- a/tests/ui/qualified/qualified-path-params-2.stderr
+++ b/tests/ui/qualified/qualified-path-params-2.stderr
@@ -7,7 +7,7 @@ LL | type A = <S as Tr>::A::f<u8>;
 help: if there were a trait named `Example` with associated type `f` implemented for `<S as Tr>::A`, you could use the fully-qualified path
    |
 LL - type A = <S as Tr>::A::f<u8>;
-LL + type A = <<S as Tr>::A as Example>::f;
+LL + type A = <<S as Tr>::A as Example>::f<u8>;
    |
 
 error: aborting due to 1 previous error
diff --git a/tests/ui/repeat-expr/copy-check-const-element-uninferred-count.rs b/tests/ui/repeat-expr/copy-check-const-element-uninferred-count.rs
new file mode 100644
index 00000000000..6115146539c
--- /dev/null
+++ b/tests/ui/repeat-expr/copy-check-const-element-uninferred-count.rs
@@ -0,0 +1,72 @@
+#![feature(generic_arg_infer)]
+
+// Test when deferring repeat expr copy checks to end of typechecking whether elements
+// that are const items allow for repeat counts to go uninferred without an error being
+// emitted if they would later wind up inferred by integer fallback.
+//
+// This test should be updated if we wind up deferring repeat expr checks until *after*
+// integer fallback as the point of the test is not *specifically* about integer fallback
+// but rather about the behaviour of `const` element exprs.
+
+trait Trait<const N: usize> {}
+
+// We impl `Trait` for both `i32` and `u32` to avoid being able
+// to prove `?int: Trait<?n>` from there only being one impl.
+impl Trait<2> for i32 {}
+impl Trait<2> for u32 {}
+
+fn tie_and_make_goal<const N: usize, T: Trait<N>>(_: &T, _: &[String; N]) {}
+
+fn const_block() {
+    // Deferred repeat expr `String; ?n`
+    let a = [const { String::new() }; _];
+
+    // `?int: Trait<?n>` goal
+    tie_and_make_goal(&1, &a);
+
+    // If repeat expr checks structurally resolve the `?n`s before checking if the
+    // element is a `const` then we would error here. Otherwise we avoid doing so,
+    // integer fallback occurs, allowing `?int: Trait<?n>` goals to make progress,
+    // inferring the repeat counts (to `2` but that doesn't matter as the element is `const`).
+}
+
+fn const_item() {
+    const MY_CONST: String = String::new();
+
+    // Deferred repeat expr `String; ?n`
+    let a = [MY_CONST; _];
+
+    // `?int: Trait<?n>` goal
+    tie_and_make_goal(&1, &a);
+
+    // ... same as `const_block`
+}
+
+fn assoc_const() {
+    trait Dummy {
+        const ASSOC: String;
+    }
+    impl Dummy for () {
+        const ASSOC: String = String::new();
+    }
+
+    // Deferred repeat expr `String; ?n`
+    let a = [<() as Dummy>::ASSOC; _];
+
+    // `?int: Trait<?n>` goal
+    tie_and_make_goal(&1, &a);
+
+    // ... same as `const_block`
+}
+
+fn const_block_but_uninferred() {
+    // Deferred repeat expr `String; ?n`
+    let a = [const { String::new() }; _];
+    //~^ ERROR: type annotations needed for `[String; _]`
+
+    // Even if we don't structurally resolve the repeat count as part of repeat expr
+    // checks, we still error on the repeat count being uninferred as we require all
+    // types/consts to be inferred by the end of type checking.
+}
+
+fn main() {}
diff --git a/tests/ui/repeat-expr/copy-check-const-element-uninferred-count.stderr b/tests/ui/repeat-expr/copy-check-const-element-uninferred-count.stderr
new file mode 100644
index 00000000000..2f52537fa94
--- /dev/null
+++ b/tests/ui/repeat-expr/copy-check-const-element-uninferred-count.stderr
@@ -0,0 +1,15 @@
+error[E0284]: type annotations needed for `[String; _]`
+  --> $DIR/copy-check-const-element-uninferred-count.rs:64:9
+   |
+LL |     let a = [const { String::new() }; _];
+   |         ^   ---------------------------- type must be known at this point
+   |
+   = note: the length of array `[String; _]` must be type `usize`
+help: consider giving `a` an explicit type, where the placeholders `_` are specified
+   |
+LL |     let a: [_; _] = [const { String::new() }; _];
+   |          ++++++++
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0284`.
diff --git a/tests/ui/repeat-expr/copy-check-deferred-after-fallback.rs b/tests/ui/repeat-expr/copy-check-deferred-after-fallback.rs
index d9ad93541ec..3f310f07de0 100644
--- a/tests/ui/repeat-expr/copy-check-deferred-after-fallback.rs
+++ b/tests/ui/repeat-expr/copy-check-deferred-after-fallback.rs
@@ -1,37 +1,53 @@
 #![feature(generic_arg_infer)]
 
-// Test that would start passing if we defer repeat expr copy checks to end of
-// typechecking and they're checked after integer fallback occurs. We accomplish
-// this by contriving a situation where integer fallback allows progress to be
-// made on a trait goal that infers the length of a repeat expr.
+// Test when deferring repeat expr copy checks to end of typechecking whether they're
+// checked before integer fallback occurs or not. We accomplish this by having a repeat
+// count that can only be inferred after integer fallback has occured. This test will
+// pass if we were to check repeat exprs after integer fallback.
 
 use std::marker::PhantomData;
-
-struct NotCopy;
+struct Foo<T>(PhantomData<T>);
+
+// We impl Copy/Clone for multiple (but not all) substitutions
+// to ensure that `Foo<?int>: Copy` can't be proven on the basis
+// of there only being one applying impl.
+impl Clone for Foo<u32> {
+    fn clone(&self) -> Self {
+        Foo(PhantomData)
+    }
+}
+impl Clone for Foo<i32> {
+    fn clone(&self) -> Self {
+        Foo(PhantomData)
+    }
+}
+impl Copy for Foo<u32> {}
+impl Copy for Foo<i32> {}
 
 trait Trait<const N: usize> {}
 
-impl Trait<2> for u32 {}
+// We impl `Trait` for both `i32` and `u32` to avoid being able
+// to prove `?int: Trait<?n>` from there only being one impl.
 impl Trait<1> for i32 {}
+impl Trait<2> for u32 {}
 
-fn make_goal<T: Trait<N>, const N: usize>(_: &T, _: [NotCopy; N]) {}
+fn tie_and_make_goal<const N: usize, T: Trait<N>>(_: &T, _: &[Foo<T>; N]) {}
 
 fn main() {
     let a = 1;
-    let b = [NotCopy; _];
-    //~^ ERROR: type annotations needed
-
-    // a is of type `?y`
-    // b is of type `[NotCopy; ?x]`
-    // there is a goal ?y: Trait<?x>` with two candidates:
-    // - `i32: Trait<1>`, ?y=i32 ?x=1 which doesnt require `NotCopy: Copy`
-    // - `u32: Trait<2>` ?y=u32 ?x=2 which requires `NotCopy: Copy`
-    make_goal(&a, b);
-
-    // final repeat expr checks:
-    //
-    // `NotCopy; ?x`
-    // - succeeds if fallback happens before repeat exprs as `i32: Trait<?x>` infers `?x=1`
-    // - fails if repeat expr checks happen first as `?x` is unconstrained so cannot be
-    //    structurally resolved
+    // Deferred repeat expr `Foo<?int>; ?n`
+    let b = [Foo(PhantomData); _];
+    //~^ ERROR: type annotations needed for `[Foo<{integer}>; _]`
+
+    // Introduces a `?int: Trait<?n>` goal
+    tie_and_make_goal(&a, &b);
+
+    // If fallback doesn't occur:
+    // - `Foo<?int>; ?n`is ambig as repeat count is unknown -> error
+
+    // If fallback occurs:
+    // - `?int` inferred to `i32`
+    // - `?int: Trait<?n>` becomes `i32: Trait<?n>` wihhc infers `?n=1`
+    // - Repeat expr check `Foo<?int>; ?n` is now `Foo<i32>; 1`
+    // - `Foo<i32>; 1` doesn't require `Foo<i32>: Copy`
 }
diff --git a/tests/ui/repeat-expr/copy-check-deferred-after-fallback.stderr b/tests/ui/repeat-expr/copy-check-deferred-after-fallback.stderr
index 2a0cb3fb7a3..103b074dda7 100644
--- a/tests/ui/repeat-expr/copy-check-deferred-after-fallback.stderr
+++ b/tests/ui/repeat-expr/copy-check-deferred-after-fallback.stderr
@@ -1,13 +1,13 @@
-error[E0282]: type annotations needed for `[NotCopy; _]`
-  --> $DIR/copy-check-deferred-after-fallback.rs:21:9
+error[E0282]: type annotations needed for `[Foo<{integer}>; _]`
+  --> $DIR/copy-check-deferred-after-fallback.rs:39:9
    |
-LL |     let b = [NotCopy; _];
-   |         ^    ------- type must be known at this point
+LL |     let b = [Foo(PhantomData); _];
+   |         ^    ---------------- type must be known at this point
    |
 help: consider giving `b` an explicit type, where the value of const parameter `N` is specified
    |
-LL |     let b: [_; N] = [NotCopy; _];
-   |          ++++++++
+LL |     let b: [Foo<{integer}>; N] = [Foo(PhantomData); _];
+   |          +++++++++++++++++++++
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/repeat-expr/copy-check-deferred-before-fallback.rs b/tests/ui/repeat-expr/copy-check-deferred-before-fallback.rs
index 4654d7483a6..4fbb8f0a00c 100644
--- a/tests/ui/repeat-expr/copy-check-deferred-before-fallback.rs
+++ b/tests/ui/repeat-expr/copy-check-deferred-before-fallback.rs
@@ -1,18 +1,13 @@
 //@ check-pass
-
 #![feature(generic_arg_infer)]
 
-// Test that if we defer repeat expr copy checks to end of typechecking they're
-// checked before integer fallback occurs. We accomplish this by contriving a
-// situation where we have a goal that can be proven either via another repeat expr
-// check or by integer fallback. In the integer fallback case an array length would
-// be inferred to `2` requiring `NotCopy: Copy`, and in the repeat expr case it would
-// be inferred to `1`.
+// Test when deferring repeat expr checks to end of typechecking whether they're
+// checked before integer fallback occurs. We accomplish this by having the repeat
+// expr check allow inference progress on an ambiguous goal, where the ambiguous goal
+// would fail if the inference variable was fallen back to `i32`. This test will
+// pass if we check repeat exprs before integer fallback.
 
 use std::marker::PhantomData;
-
-struct NotCopy;
-
 struct Foo<T>(PhantomData<T>);
 
 impl Clone for Foo<u32> {
@@ -20,40 +15,34 @@ impl Clone for Foo<u32> {
         Foo(PhantomData)
     }
 }
-
 impl Copy for Foo<u32> {}
 
-fn tie<T>(_: &T, _: [Foo<T>; 2]) {}
+trait Trait {}
 
-trait Trait<const N: usize> {}
+// Two impls just to ensure that `?int: Trait` wont itself succeed by unifying with
+// a self type on an impl here. It also ensures that integer fallback would actually
+// be valid for all of the stalled goals incase that's ever something we take into account.
+impl Trait for i32 {}
+impl Trait for u32 {}
 
-impl Trait<2> for i32 {}
-impl Trait<1> for u32 {}
-
-fn make_goal<T: Trait<N>, const N: usize>(_: &T, _: [NotCopy; N]) {}
+fn make_goal<T: Trait>(_: &T) {}
+fn tie<T>(_: &T, _: &[Foo<T>; 2]) {}
 
 fn main() {
     let a = 1;
+    // `?int: Trait`
+    make_goal(&a);
+
+    // Deferred `Foo<?int>: Copy` requirement
     let b: [Foo<_>; 2] = [Foo(PhantomData); _];
-    tie(&a, b);
-    let c = [NotCopy; _];
-
-    // a is of type `?y`
-    // b is of type `[Foo<?y>; 2]`
-    // c is of type `[NotCopy; ?x]`
-    // there is a goal ?y: Trait<?x>` with two candidates:
-    // - `i32: Trait<2>`, ?y=i32 ?x=2 which requires `NotCopy: Copy` when expr checks happen
-    // - `u32: Trait<1>` ?y=u32 ?x=1 which doesnt require `NotCopy: Copy`
-    make_goal(&a, c);
-
-    // final repeat expr checks:
-    //
-    // `Foo<?y>; 2`
-    // - Foo<?y>: Copy
-    // - requires ?y=u32
-    //
-    // `NotCopy; ?x`
-    // - fails if fallback happens before repeat exprs as `i32: Trait<?x>` infers `?x=2`
-    // - succeeds if repeat expr checks happen first as `?y=u32` means `u32: Trait<?x>`
-    //    infers `?x=1`
+    tie(&a, &b);
+
+    // If fallback doesn't occur:
+    // - `Foo<?int>; 2`is > 1, needs copy
+    // - `Foo<?int>: Copy` infers `?int=u32`
+    // - stalled goal `?int: Trait` can now make progress and succeed
+
+    // If fallback occurs:
+    // - `Foo<i32>; 2` is > 1, needs copy
+    // - `Foo<i32>: Copy` doesn't hold -> error
 }
diff --git a/tests/ui/repeat-expr/copy-check-inference-side-effects.rs b/tests/ui/repeat-expr/copy-check-inference-side-effects.rs
new file mode 100644
index 00000000000..4e3bfdead26
--- /dev/null
+++ b/tests/ui/repeat-expr/copy-check-inference-side-effects.rs
@@ -0,0 +1,34 @@
+#![feature(generic_arg_infer)]
+
+struct Foo<const N: usize>;
+
+impl Clone for Foo<1> {
+    fn clone(&self) -> Self {
+        Self
+    }
+}
+impl Copy for Foo<1> {}
+
+fn unify<const N: usize>(_: &[Foo<N>; 2], _: &[String; N]) {}
+
+fn works_if_inference_side_effects() {
+    // This will only pass if inference side effects from proving `Foo<?x>: Copy` are
+    // able to be relied upon by other repeat expressions.
+    let a /* : [Foo<?x>; 2] */ = [Foo::<_>; 2];
+    //~^ ERROR: type annotations needed for `[Foo<_>; 2]`
+    let b /* : [String; ?x] */ = ["string".to_string(); _];
+
+    unify(&a, &b);
+}
+
+fn works_if_fixed_point() {
+    // This will only pass if the *second* array repeat expr is checked first
+    // allowing `Foo<?x>: Copy` to infer the array length of the first repeat expr.
+    let b /* : [String; ?x] */ = ["string".to_string(); _];
+    //~^ ERROR: type annotations needed for `[String; _]`
+    let a /* : [Foo<?x>; 2] */ = [Foo::<_>; 2];
+
+    unify(&a, &b);
+}
+
+fn main() {}
diff --git a/tests/ui/repeat-expr/copy-check-inference-side-effects.stderr b/tests/ui/repeat-expr/copy-check-inference-side-effects.stderr
new file mode 100644
index 00000000000..505beff0f6b
--- /dev/null
+++ b/tests/ui/repeat-expr/copy-check-inference-side-effects.stderr
@@ -0,0 +1,28 @@
+error[E0282]: type annotations needed for `[Foo<_>; 2]`
+  --> $DIR/copy-check-inference-side-effects.rs:17:9
+   |
+LL |     let a /* : [Foo<?x>; 2] */ = [Foo::<_>; 2];
+   |         ^
+LL |
+LL |     let b /* : [String; ?x] */ = ["string".to_string(); _];
+   |                                   -------------------- type must be known at this point
+   |
+help: consider giving `a` an explicit type, where the value of const parameter `N` is specified
+   |
+LL |     let a: [Foo<N>; 2] /* : [Foo<?x>; 2] */ = [Foo::<_>; 2];
+   |          +++++++++++++
+
+error[E0282]: type annotations needed for `[String; _]`
+  --> $DIR/copy-check-inference-side-effects.rs:27:9
+   |
+LL |     let b /* : [String; ?x] */ = ["string".to_string(); _];
+   |         ^                         -------------------- type must be known at this point
+   |
+help: consider giving `b` an explicit type, where the value of const parameter `N` is specified
+   |
+LL |     let b: [_; N] /* : [String; ?x] */ = ["string".to_string(); _];
+   |          ++++++++
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/tests/ui/repeat-expr/copy-inference-side-effects-are-lazy.rs b/tests/ui/repeat-expr/copy-inference-side-effects-are-lazy.rs
index 0b0672d9c2b..d50466ac4bb 100644
--- a/tests/ui/repeat-expr/copy-inference-side-effects-are-lazy.rs
+++ b/tests/ui/repeat-expr/copy-inference-side-effects-are-lazy.rs
@@ -1,8 +1,3 @@
-//@revisions: current gai
-//@[current] check-pass
-
-#![cfg_attr(gai, feature(generic_arg_infer))]
-
 use std::marker::PhantomData;
 
 struct Foo<T>(PhantomData<T>);
@@ -20,6 +15,6 @@ fn extract<T, const N: usize>(_: [Foo<T>; N]) -> T {
 
 fn main() {
     let x = [Foo(PhantomData); 2];
-    //[gai]~^ ERROR: type annotations needed
-    _ = extract(x).max(2);
+    //~^ ERROR: type annotations needed
+    extract(x).max(2);
 }
diff --git a/tests/ui/repeat-expr/copy-inference-side-effects-are-lazy.stderr b/tests/ui/repeat-expr/copy-inference-side-effects-are-lazy.stderr
new file mode 100644
index 00000000000..ba44beb76db
--- /dev/null
+++ b/tests/ui/repeat-expr/copy-inference-side-effects-are-lazy.stderr
@@ -0,0 +1,17 @@
+error[E0282]: type annotations needed for `[Foo<_>; 2]`
+  --> $DIR/copy-inference-side-effects-are-lazy.rs:17:9
+   |
+LL |     let x = [Foo(PhantomData); 2];
+   |         ^
+LL |
+LL |     extract(x).max(2);
+   |     ---------- type must be known at this point
+   |
+help: consider giving `x` an explicit type, where the type for type parameter `T` is specified
+   |
+LL |     let x: [Foo<T>; 2] = [Foo(PhantomData); 2];
+   |          +++++++++++++
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/tests/ui/self/dispatch-dyn-incompatible-that-does-not-deref.rs b/tests/ui/self/dispatch-dyn-incompatible-that-does-not-deref.rs
new file mode 100644
index 00000000000..af35d1e0359
--- /dev/null
+++ b/tests/ui/self/dispatch-dyn-incompatible-that-does-not-deref.rs
@@ -0,0 +1,18 @@
+// Regression test for <https://github.com/rust-lang/rust/issues/141419>.
+
+use std::ops::Deref;
+
+struct W;
+
+trait Foo: Deref<Target = W> {
+    fn method(self: &W) {}
+    //~^ ERROR invalid `self` parameter type: `&W`
+}
+
+fn test(x: &dyn Foo) {
+    //~^ ERROR the trait `Foo` is not dyn compatible
+    x.method();
+    //~^ ERROR the trait `Foo` is not dyn compatible
+}
+
+fn main() {}
diff --git a/tests/ui/self/dispatch-dyn-incompatible-that-does-not-deref.stderr b/tests/ui/self/dispatch-dyn-incompatible-that-does-not-deref.stderr
new file mode 100644
index 00000000000..237bbc56715
--- /dev/null
+++ b/tests/ui/self/dispatch-dyn-incompatible-that-does-not-deref.stderr
@@ -0,0 +1,49 @@
+error[E0038]: the trait `Foo` is not dyn compatible
+  --> $DIR/dispatch-dyn-incompatible-that-does-not-deref.rs:12:13
+   |
+LL |     fn method(self: &W) {}
+   |                     -- help: consider changing method `method`'s `self` parameter to be `&self`: `&Self`
+...
+LL | fn test(x: &dyn Foo) {
+   |             ^^^^^^^ `Foo` is not dyn compatible
+   |
+note: for a trait to be dyn compatible it needs to allow building a vtable
+      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
+  --> $DIR/dispatch-dyn-incompatible-that-does-not-deref.rs:8:21
+   |
+LL | trait Foo: Deref<Target = W> {
+   |       --- this trait is not dyn compatible...
+LL |     fn method(self: &W) {}
+   |                     ^^ ...because method `method`'s `self` parameter cannot be dispatched on
+
+error[E0307]: invalid `self` parameter type: `&W`
+  --> $DIR/dispatch-dyn-incompatible-that-does-not-deref.rs:8:21
+   |
+LL |     fn method(self: &W) {}
+   |                     ^^
+   |
+   = note: type of `self` must be `Self` or a type that dereferences to it
+   = help: consider changing to `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
+
+error[E0038]: the trait `Foo` is not dyn compatible
+  --> $DIR/dispatch-dyn-incompatible-that-does-not-deref.rs:14:5
+   |
+LL |     fn method(self: &W) {}
+   |                     -- help: consider changing method `method`'s `self` parameter to be `&self`: `&Self`
+...
+LL |     x.method();
+   |     ^^^^^^^^^^ `Foo` is not dyn compatible
+   |
+note: for a trait to be dyn compatible it needs to allow building a vtable
+      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
+  --> $DIR/dispatch-dyn-incompatible-that-does-not-deref.rs:8:21
+   |
+LL | trait Foo: Deref<Target = W> {
+   |       --- this trait is not dyn compatible...
+LL |     fn method(self: &W) {}
+   |                     ^^ ...because method `method`'s `self` parameter cannot be dispatched on
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0038, E0307.
+For more information about an error, try `rustc --explain E0038`.
diff --git a/tests/ui/self/self-impl.stderr b/tests/ui/self/self-impl.stderr
index 18ffd15427f..1bda307d0eb 100644
--- a/tests/ui/self/self-impl.stderr
+++ b/tests/ui/self/self-impl.stderr
@@ -2,13 +2,25 @@ error[E0223]: ambiguous associated type
   --> $DIR/self-impl.rs:23:16
    |
 LL |         let _: <Self>::Baz = true;
-   |                ^^^^^^^^^^^ help: use fully-qualified syntax: `<Bar as Foo>::Baz`
+   |                ^^^^^^^^^^^
+   |
+help: use fully-qualified syntax
+   |
+LL -         let _: <Self>::Baz = true;
+LL +         let _: <Bar as Foo>::Baz = true;
+   |
 
 error[E0223]: ambiguous associated type
   --> $DIR/self-impl.rs:25:16
    |
 LL |         let _: Self::Baz = true;
-   |                ^^^^^^^^^ help: use fully-qualified syntax: `<Bar as Foo>::Baz`
+   |                ^^^^^^^^^
+   |
+help: use fully-qualified syntax
+   |
+LL -         let _: Self::Baz = true;
+LL +         let _: <Bar as Foo>::Baz = true;
+   |
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/structs/struct-path-associated-type.stderr b/tests/ui/structs/struct-path-associated-type.stderr
index de396e875b0..110362293ac 100644
--- a/tests/ui/structs/struct-path-associated-type.stderr
+++ b/tests/ui/structs/struct-path-associated-type.stderr
@@ -48,19 +48,37 @@ error[E0223]: ambiguous associated type
   --> $DIR/struct-path-associated-type.rs:32:13
    |
 LL |     let s = S::A {};
-   |             ^^^^ help: use fully-qualified syntax: `<S as Tr>::A`
+   |             ^^^^
+   |
+help: use fully-qualified syntax
+   |
+LL -     let s = S::A {};
+LL +     let s = <S as Tr>::A {};
+   |
 
 error[E0223]: ambiguous associated type
   --> $DIR/struct-path-associated-type.rs:33:13
    |
 LL |     let z = S::A::<u8> {};
-   |             ^^^^ help: use fully-qualified syntax: `<S as Tr>::A`
+   |             ^^^^
+   |
+help: use fully-qualified syntax
+   |
+LL -     let z = S::A::<u8> {};
+LL +     let z = <S as Tr>::A::<u8> {};
+   |
 
 error[E0223]: ambiguous associated type
   --> $DIR/struct-path-associated-type.rs:35:9
    |
 LL |         S::A {} => {}
-   |         ^^^^ help: use fully-qualified syntax: `<S as Tr>::A`
+   |         ^^^^
+   |
+help: use fully-qualified syntax
+   |
+LL -         S::A {} => {}
+LL +         <S as Tr>::A {} => {}
+   |
 
 error: aborting due to 8 previous errors
 
diff --git a/tests/ui/target-feature/abi-incompatible-target-feature-attribute-fcw.rs b/tests/ui/target-feature/abi-incompatible-target-feature-attribute-fcw.rs
new file mode 100644
index 00000000000..270874a9f58
--- /dev/null
+++ b/tests/ui/target-feature/abi-incompatible-target-feature-attribute-fcw.rs
@@ -0,0 +1,14 @@
+//@ compile-flags: --crate-type=lib
+//@ compile-flags: --target=aarch64-unknown-none-softfloat
+//@ needs-llvm-components: aarch64
+#![feature(no_core, lang_items)]
+#![no_core]
+#![deny(aarch64_softfloat_neon)]
+
+#[lang = "sized"]
+pub trait Sized {}
+
+#[target_feature(enable = "neon")]
+//~^ERROR: enabling the `neon` target feature on the current target is unsound
+//~|WARN: previously accepted
+pub unsafe fn my_fun() {}
diff --git a/tests/ui/target-feature/abi-incompatible-target-feature-attribute-fcw.stderr b/tests/ui/target-feature/abi-incompatible-target-feature-attribute-fcw.stderr
new file mode 100644
index 00000000000..bf745291a5a
--- /dev/null
+++ b/tests/ui/target-feature/abi-incompatible-target-feature-attribute-fcw.stderr
@@ -0,0 +1,31 @@
+error: enabling the `neon` target feature on the current target is unsound due to ABI issues
+  --> $DIR/abi-incompatible-target-feature-attribute-fcw.rs:11:18
+   |
+LL | #[target_feature(enable = "neon")]
+   |                  ^^^^^^^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #134375 <https://github.com/rust-lang/rust/issues/134375>
+note: the lint level is defined here
+  --> $DIR/abi-incompatible-target-feature-attribute-fcw.rs:6:9
+   |
+LL | #![deny(aarch64_softfloat_neon)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
+Future incompatibility report: Future breakage diagnostic:
+error: enabling the `neon` target feature on the current target is unsound due to ABI issues
+  --> $DIR/abi-incompatible-target-feature-attribute-fcw.rs:11:18
+   |
+LL | #[target_feature(enable = "neon")]
+   |                  ^^^^^^^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #134375 <https://github.com/rust-lang/rust/issues/134375>
+note: the lint level is defined here
+  --> $DIR/abi-incompatible-target-feature-attribute-fcw.rs:6:9
+   |
+LL | #![deny(aarch64_softfloat_neon)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^
+
diff --git a/tests/ui/traits/item-privacy.stderr b/tests/ui/traits/item-privacy.stderr
index 4fd9ef91192..1d3d8cb9843 100644
--- a/tests/ui/traits/item-privacy.stderr
+++ b/tests/ui/traits/item-privacy.stderr
@@ -230,13 +230,25 @@ error[E0223]: ambiguous associated type
   --> $DIR/item-privacy.rs:119:12
    |
 LL |     let _: S::B;
-   |            ^^^^ help: use fully-qualified syntax: `<S as assoc_ty::B>::B`
+   |            ^^^^
+   |
+help: use fully-qualified syntax
+   |
+LL -     let _: S::B;
+LL +     let _: <S as assoc_ty::B>::B;
+   |
 
 error[E0223]: ambiguous associated type
   --> $DIR/item-privacy.rs:120:12
    |
 LL |     let _: S::C;
-   |            ^^^^ help: use fully-qualified syntax: `<S as assoc_ty::C>::C`
+   |            ^^^^
+   |
+help: use fully-qualified syntax
+   |
+LL -     let _: S::C;
+LL +     let _: <S as assoc_ty::C>::C;
+   |
 
 error[E0624]: associated type `A` is private
   --> $DIR/item-privacy.rs:122:12
diff --git a/tests/ui/traits/test-2.rs b/tests/ui/traits/test-2.rs
index ffb778a0141..4ee880da87a 100644
--- a/tests/ui/traits/test-2.rs
+++ b/tests/ui/traits/test-2.rs
@@ -13,5 +13,4 @@ fn main() {
     (Box::new(10) as Box<dyn bar>).dup();
     //~^ ERROR E0038
     //~| ERROR E0038
-    //~| ERROR E0038
 }
diff --git a/tests/ui/traits/test-2.stderr b/tests/ui/traits/test-2.stderr
index 6a6cb503aa4..b52839c300e 100644
--- a/tests/ui/traits/test-2.stderr
+++ b/tests/ui/traits/test-2.stderr
@@ -50,29 +50,6 @@ LL | trait bar { fn dup(&self) -> Self; fn blah<X>(&self); }
            implementing `bar` for this new enum and using it instead
 
 error[E0038]: the trait `bar` is not dyn compatible
-  --> $DIR/test-2.rs:13:5
-   |
-LL |     (Box::new(10) as Box<dyn bar>).dup();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `bar` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $DIR/test-2.rs:4:30
-   |
-LL | trait bar { fn dup(&self) -> Self; fn blah<X>(&self); }
-   |       ---                    ^^^^     ^^^^ ...because method `blah` has generic type parameters
-   |       |                      |
-   |       |                      ...because method `dup` references the `Self` type in its return type
-   |       this trait is not dyn compatible...
-   = help: consider moving `dup` to another trait
-   = help: consider moving `blah` to another trait
-   = help: the following types implement `bar`:
-             i32
-             u32
-           consider defining an enum where each variant holds one of these types,
-           implementing `bar` for this new enum and using it instead
-
-error[E0038]: the trait `bar` is not dyn compatible
   --> $DIR/test-2.rs:13:6
    |
 LL |     (Box::new(10) as Box<dyn bar>).dup();
@@ -96,7 +73,7 @@ LL | trait bar { fn dup(&self) -> Self; fn blah<X>(&self); }
            implementing `bar` for this new enum and using it instead
    = note: required for the cast from `Box<{integer}>` to `Box<dyn bar>`
 
-error: aborting due to 5 previous errors
+error: aborting due to 4 previous errors
 
 Some errors have detailed explanations: E0038, E0107.
 For more information about an error, try `rustc --explain E0038`.
diff --git a/tests/ui/transmute/unnecessary-transmutation.fixed b/tests/ui/transmute/unnecessary-transmutation.fixed
index f6478c5aa5c..08010ec8b84 100644
--- a/tests/ui/transmute/unnecessary-transmutation.fixed
+++ b/tests/ui/transmute/unnecessary-transmutation.fixed
@@ -8,7 +8,27 @@ pub fn bytes_at_home(x: u32) -> [u8; 4] {
     //~^ ERROR
 }
 
+pub const fn intinator_const(from: bool) -> u8 {
+    unsafe { (from) as u8 }
+    //~^ ERROR
+}
+
+pub static X: u8 = unsafe { (true) as u8 };
+//~^ ERROR
+pub const Y: u8 = unsafe { (true) as u8 };
+//~^ ERROR
+
+pub struct Z {}
+impl Z {
+    pub const fn intinator_assoc(x: bool) -> u8 {
+        unsafe { (x) as u8 }
+        //~^ ERROR
+    }
+}
+
 fn main() {
+    const { unsafe { (true) as u8 } };
+    //~^ ERROR
     unsafe {
         let x: u16 = u16::from_ne_bytes(*b"01");
         //~^ ERROR
@@ -83,12 +103,12 @@ fn main() {
 
         let z: bool = transmute(1u8);
         // clippy
-        let z: u8 = (z) as u8;
+        let z: u8 = u8::from(z);
         //~^ ERROR
 
         let z: bool = transmute(1i8);
         // clippy
-        let z: i8 = (z) as i8;
+        let z: i8 = i8::from(z);
         //~^ ERROR
     }
 }
diff --git a/tests/ui/transmute/unnecessary-transmutation.rs b/tests/ui/transmute/unnecessary-transmutation.rs
index ab0af03acc2..43eefb97dc2 100644
--- a/tests/ui/transmute/unnecessary-transmutation.rs
+++ b/tests/ui/transmute/unnecessary-transmutation.rs
@@ -8,7 +8,27 @@ pub fn bytes_at_home(x: u32) -> [u8; 4] {
     //~^ ERROR
 }
 
+pub const fn intinator_const(from: bool) -> u8 {
+    unsafe { transmute(from) }
+    //~^ ERROR
+}
+
+pub static X: u8 = unsafe { transmute(true) };
+//~^ ERROR
+pub const Y: u8 = unsafe { transmute(true) };
+//~^ ERROR
+
+pub struct Z {}
+impl Z {
+    pub const fn intinator_assoc(x: bool) -> u8 {
+        unsafe { transmute(x) }
+        //~^ ERROR
+    }
+}
+
 fn main() {
+    const { unsafe { transmute::<_, u8>(true) } };
+    //~^ ERROR
     unsafe {
         let x: u16 = transmute(*b"01");
         //~^ ERROR
diff --git a/tests/ui/transmute/unnecessary-transmutation.stderr b/tests/ui/transmute/unnecessary-transmutation.stderr
index 59e933bbc81..602e964f5b2 100644
--- a/tests/ui/transmute/unnecessary-transmutation.stderr
+++ b/tests/ui/transmute/unnecessary-transmutation.stderr
@@ -1,10 +1,9 @@
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:7:14
+  --> $DIR/unnecessary-transmutation.rs:16:29
    |
-LL |     unsafe { transmute(x) }
-   |              ^^^^^^^^^^^^ help: replace this with: `u32::to_ne_bytes(x)`
+LL | pub static X: u8 = unsafe { transmute(true) };
+   |                             ^^^^^^^^^^^^^^^ help: replace this with: `(true) as u8`
    |
-   = help: there's also `to_le_bytes` and `to_be_bytes` if you expect a particular byte order
 note: the lint level is defined here
   --> $DIR/unnecessary-transmutation.rs:2:9
    |
@@ -12,7 +11,33 @@ LL | #![deny(unnecessary_transmutes)]
    |         ^^^^^^^^^^^^^^^^^^^^^^
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:13:22
+  --> $DIR/unnecessary-transmutation.rs:18:28
+   |
+LL | pub const Y: u8 = unsafe { transmute(true) };
+   |                            ^^^^^^^^^^^^^^^ help: replace this with: `(true) as u8`
+
+error: unnecessary transmute
+  --> $DIR/unnecessary-transmutation.rs:7:14
+   |
+LL |     unsafe { transmute(x) }
+   |              ^^^^^^^^^^^^ help: replace this with: `u32::to_ne_bytes(x)`
+   |
+   = help: there's also `to_le_bytes` and `to_be_bytes` if you expect a particular byte order
+
+error: unnecessary transmute
+  --> $DIR/unnecessary-transmutation.rs:12:14
+   |
+LL |     unsafe { transmute(from) }
+   |              ^^^^^^^^^^^^^^^ help: replace this with: `(from) as u8`
+
+error: unnecessary transmute
+  --> $DIR/unnecessary-transmutation.rs:24:18
+   |
+LL |         unsafe { transmute(x) }
+   |                  ^^^^^^^^^^^^ help: replace this with: `(x) as u8`
+
+error: unnecessary transmute
+  --> $DIR/unnecessary-transmutation.rs:33:22
    |
 LL |         let x: u16 = transmute(*b"01");
    |                      ^^^^^^^^^^^^^^^^^ help: replace this with: `u16::from_ne_bytes(*b"01")`
@@ -20,7 +45,7 @@ LL |         let x: u16 = transmute(*b"01");
    = help: there's also `from_le_bytes` and `from_be_bytes` if you expect a particular byte order
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:15:26
+  --> $DIR/unnecessary-transmutation.rs:35:26
    |
 LL |         let x: [u8; 2] = transmute(x);
    |                          ^^^^^^^^^^^^ help: replace this with: `u16::to_ne_bytes(x)`
@@ -28,7 +53,7 @@ LL |         let x: [u8; 2] = transmute(x);
    = help: there's also `to_le_bytes` and `to_be_bytes` if you expect a particular byte order
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:17:22
+  --> $DIR/unnecessary-transmutation.rs:37:22
    |
 LL |         let x: u32 = transmute(*b"0123");
    |                      ^^^^^^^^^^^^^^^^^^^ help: replace this with: `u32::from_ne_bytes(*b"0123")`
@@ -36,7 +61,7 @@ LL |         let x: u32 = transmute(*b"0123");
    = help: there's also `from_le_bytes` and `from_be_bytes` if you expect a particular byte order
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:19:26
+  --> $DIR/unnecessary-transmutation.rs:39:26
    |
 LL |         let x: [u8; 4] = transmute(x);
    |                          ^^^^^^^^^^^^ help: replace this with: `u32::to_ne_bytes(x)`
@@ -44,7 +69,7 @@ LL |         let x: [u8; 4] = transmute(x);
    = help: there's also `to_le_bytes` and `to_be_bytes` if you expect a particular byte order
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:21:22
+  --> $DIR/unnecessary-transmutation.rs:41:22
    |
 LL |         let x: u64 = transmute(*b"feriscat");
    |                      ^^^^^^^^^^^^^^^^^^^^^^^ help: replace this with: `u64::from_ne_bytes(*b"feriscat")`
@@ -52,7 +77,7 @@ LL |         let x: u64 = transmute(*b"feriscat");
    = help: there's also `from_le_bytes` and `from_be_bytes` if you expect a particular byte order
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:23:26
+  --> $DIR/unnecessary-transmutation.rs:43:26
    |
 LL |         let x: [u8; 8] = transmute(x);
    |                          ^^^^^^^^^^^^ help: replace this with: `u64::to_ne_bytes(x)`
@@ -60,7 +85,7 @@ LL |         let x: [u8; 8] = transmute(x);
    = help: there's also `to_le_bytes` and `to_be_bytes` if you expect a particular byte order
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:26:22
+  --> $DIR/unnecessary-transmutation.rs:46:22
    |
 LL |         let y: i16 = transmute(*b"01");
    |                      ^^^^^^^^^^^^^^^^^ help: replace this with: `i16::from_ne_bytes(*b"01")`
@@ -68,7 +93,7 @@ LL |         let y: i16 = transmute(*b"01");
    = help: there's also `from_le_bytes` and `from_be_bytes` if you expect a particular byte order
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:28:26
+  --> $DIR/unnecessary-transmutation.rs:48:26
    |
 LL |         let y: [u8; 2] = transmute(y);
    |                          ^^^^^^^^^^^^ help: replace this with: `i16::to_ne_bytes(y)`
@@ -76,7 +101,7 @@ LL |         let y: [u8; 2] = transmute(y);
    = help: there's also `to_le_bytes` and `to_be_bytes` if you expect a particular byte order
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:30:22
+  --> $DIR/unnecessary-transmutation.rs:50:22
    |
 LL |         let y: i32 = transmute(*b"0123");
    |                      ^^^^^^^^^^^^^^^^^^^ help: replace this with: `i32::from_ne_bytes(*b"0123")`
@@ -84,7 +109,7 @@ LL |         let y: i32 = transmute(*b"0123");
    = help: there's also `from_le_bytes` and `from_be_bytes` if you expect a particular byte order
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:32:26
+  --> $DIR/unnecessary-transmutation.rs:52:26
    |
 LL |         let y: [u8; 4] = transmute(y);
    |                          ^^^^^^^^^^^^ help: replace this with: `i32::to_ne_bytes(y)`
@@ -92,7 +117,7 @@ LL |         let y: [u8; 4] = transmute(y);
    = help: there's also `to_le_bytes` and `to_be_bytes` if you expect a particular byte order
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:34:22
+  --> $DIR/unnecessary-transmutation.rs:54:22
    |
 LL |         let y: i64 = transmute(*b"feriscat");
    |                      ^^^^^^^^^^^^^^^^^^^^^^^ help: replace this with: `i64::from_ne_bytes(*b"feriscat")`
@@ -100,7 +125,7 @@ LL |         let y: i64 = transmute(*b"feriscat");
    = help: there's also `from_le_bytes` and `from_be_bytes` if you expect a particular byte order
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:36:26
+  --> $DIR/unnecessary-transmutation.rs:56:26
    |
 LL |         let y: [u8; 8] = transmute(y);
    |                          ^^^^^^^^^^^^ help: replace this with: `i64::to_ne_bytes(y)`
@@ -108,7 +133,7 @@ LL |         let y: [u8; 8] = transmute(y);
    = help: there's also `to_le_bytes` and `to_be_bytes` if you expect a particular byte order
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:39:22
+  --> $DIR/unnecessary-transmutation.rs:59:22
    |
 LL |         let z: f32 = transmute(*b"0123");
    |                      ^^^^^^^^^^^^^^^^^^^ help: replace this with: `f32::from_ne_bytes(*b"0123")`
@@ -116,7 +141,7 @@ LL |         let z: f32 = transmute(*b"0123");
    = help: there's also `from_le_bytes` and `from_be_bytes` if you expect a particular byte order
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:41:26
+  --> $DIR/unnecessary-transmutation.rs:61:26
    |
 LL |         let z: [u8; 4] = transmute(z);
    |                          ^^^^^^^^^^^^ help: replace this with: `f32::to_ne_bytes(z)`
@@ -124,7 +149,7 @@ LL |         let z: [u8; 4] = transmute(z);
    = help: there's also `to_le_bytes` and `to_be_bytes` if you expect a particular byte order
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:43:22
+  --> $DIR/unnecessary-transmutation.rs:63:22
    |
 LL |         let z: f64 = transmute(*b"feriscat");
    |                      ^^^^^^^^^^^^^^^^^^^^^^^ help: replace this with: `f64::from_ne_bytes(*b"feriscat")`
@@ -132,7 +157,7 @@ LL |         let z: f64 = transmute(*b"feriscat");
    = help: there's also `from_le_bytes` and `from_be_bytes` if you expect a particular byte order
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:45:26
+  --> $DIR/unnecessary-transmutation.rs:65:26
    |
 LL |         let z: [u8; 8] = transmute(z);
    |                          ^^^^^^^^^^^^ help: replace this with: `f64::to_ne_bytes(z)`
@@ -140,13 +165,13 @@ LL |         let z: [u8; 8] = transmute(z);
    = help: there's also `to_le_bytes` and `to_be_bytes` if you expect a particular byte order
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:48:22
+  --> $DIR/unnecessary-transmutation.rs:68:22
    |
 LL |         let y: u32 = transmute('🦀');
    |                      ^^^^^^^^^^^^^^^ help: replace this with: `u32::from('🦀')`
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:50:23
+  --> $DIR/unnecessary-transmutation.rs:70:23
    |
 LL |         let y: char = transmute(y);
    |                       ^^^^^^^^^^^^ help: replace this with: `char::from_u32_unchecked(y)`
@@ -154,13 +179,13 @@ LL |         let y: char = transmute(y);
    = help: consider `char::from_u32(…).unwrap()`
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:52:22
+  --> $DIR/unnecessary-transmutation.rs:72:22
    |
 LL |         let y: i32 = transmute('🐱');
    |                      ^^^^^^^^^^^^^^^ help: replace this with: `u32::from('🐱').cast_signed()`
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:54:23
+  --> $DIR/unnecessary-transmutation.rs:74:23
    |
 LL |         let y: char = transmute(y);
    |                       ^^^^^^^^^^^^ help: replace this with: `char::from_u32_unchecked(i32::cast_unsigned(y))`
@@ -168,88 +193,94 @@ LL |         let y: char = transmute(y);
    = help: consider `char::from_u32(i32::cast_unsigned(…)).unwrap()`
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:57:22
+  --> $DIR/unnecessary-transmutation.rs:77:22
    |
 LL |         let x: u16 = transmute(8i16);
    |                      ^^^^^^^^^^^^^^^ help: replace this with: `i16::cast_unsigned(8i16)`
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:59:22
+  --> $DIR/unnecessary-transmutation.rs:79:22
    |
 LL |         let x: i16 = transmute(x);
    |                      ^^^^^^^^^^^^ help: replace this with: `u16::cast_signed(x)`
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:61:22
+  --> $DIR/unnecessary-transmutation.rs:81:22
    |
 LL |         let x: u32 = transmute(4i32);
    |                      ^^^^^^^^^^^^^^^ help: replace this with: `i32::cast_unsigned(4i32)`
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:63:22
+  --> $DIR/unnecessary-transmutation.rs:83:22
    |
 LL |         let x: i32 = transmute(x);
    |                      ^^^^^^^^^^^^ help: replace this with: `u32::cast_signed(x)`
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:65:22
+  --> $DIR/unnecessary-transmutation.rs:85:22
    |
 LL |         let x: u64 = transmute(7i64);
    |                      ^^^^^^^^^^^^^^^ help: replace this with: `i64::cast_unsigned(7i64)`
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:67:22
+  --> $DIR/unnecessary-transmutation.rs:87:22
    |
 LL |         let x: i64 = transmute(x);
    |                      ^^^^^^^^^^^^ help: replace this with: `u64::cast_signed(x)`
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:70:22
+  --> $DIR/unnecessary-transmutation.rs:90:22
    |
 LL |         let y: f32 = transmute(1u32);
    |                      ^^^^^^^^^^^^^^^ help: replace this with: `f32::from_bits(1u32)`
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:72:22
+  --> $DIR/unnecessary-transmutation.rs:92:22
    |
 LL |         let y: u32 = transmute(y);
    |                      ^^^^^^^^^^^^ help: replace this with: `f32::to_bits(y)`
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:74:22
+  --> $DIR/unnecessary-transmutation.rs:94:22
    |
 LL |         let y: f64 = transmute(3u64);
    |                      ^^^^^^^^^^^^^^^ help: replace this with: `f64::from_bits(3u64)`
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:76:22
+  --> $DIR/unnecessary-transmutation.rs:96:22
    |
 LL |         let y: u64 = transmute(2.0);
    |                      ^^^^^^^^^^^^^^ help: replace this with: `f64::to_bits(2.0)`
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:79:22
+  --> $DIR/unnecessary-transmutation.rs:99:22
    |
 LL |         let y: f64 = transmute(1i64);
    |                      ^^^^^^^^^^^^^^^ help: replace this with: `f64::from_bits(i64::cast_unsigned(1i64))`
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:81:22
+  --> $DIR/unnecessary-transmutation.rs:101:22
    |
 LL |         let y: i64 = transmute(1f64);
    |                      ^^^^^^^^^^^^^^^ help: replace this with: `f64::to_bits(1f64).cast_signed()`
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:86:21
+  --> $DIR/unnecessary-transmutation.rs:106:21
    |
 LL |         let z: u8 = transmute(z);
-   |                     ^^^^^^^^^^^^ help: replace this with: `(z) as u8`
+   |                     ^^^^^^^^^^^^ help: replace this with: `u8::from(z)`
 
 error: unnecessary transmute
-  --> $DIR/unnecessary-transmutation.rs:91:21
+  --> $DIR/unnecessary-transmutation.rs:111:21
    |
 LL |         let z: i8 = transmute(z);
-   |                     ^^^^^^^^^^^^ help: replace this with: `(z) as i8`
+   |                     ^^^^^^^^^^^^ help: replace this with: `i8::from(z)`
+
+error: unnecessary transmute
+  --> $DIR/unnecessary-transmutation.rs:30:22
+   |
+LL |     const { unsafe { transmute::<_, u8>(true) } };
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^ help: replace this with: `(true) as u8`
 
-error: aborting due to 35 previous errors
+error: aborting due to 40 previous errors
 
diff --git a/tests/ui/type-alias-impl-trait/in-where-clause.stderr b/tests/ui/type-alias-impl-trait/in-where-clause.stderr
index 9fcb26c20a6..81be8c8362e 100644
--- a/tests/ui/type-alias-impl-trait/in-where-clause.stderr
+++ b/tests/ui/type-alias-impl-trait/in-where-clause.stderr
@@ -62,6 +62,11 @@ LL | / fn foo() -> Bar
 LL | | where
 LL | |     Bar: Send,
    | |______________^
+note: ...which requires computing revealed normalized predicates of `foo::{constant#0}`...
+  --> $DIR/in-where-clause.rs:13:9
+   |
+LL |     [0; 1 + 2]
+   |         ^^^^^
    = note: ...which requires revealing opaque types in `[Binder { value: TraitPredicate(<Bar as core::marker::Send>, polarity:Positive), bound_vars: [] }]`...
 note: ...which requires computing type of `Bar::{opaque#0}`...
   --> $DIR/in-where-clause.rs:5:12
diff --git a/tests/ui/typeck/closure-ty-mismatch-issue-128561.rs b/tests/ui/typeck/closure-ty-mismatch-issue-128561.rs
new file mode 100644
index 00000000000..589a90e71d6
--- /dev/null
+++ b/tests/ui/typeck/closure-ty-mismatch-issue-128561.rs
@@ -0,0 +1,10 @@
+fn main() {
+    b"abc".iter().for_each(|x| x); //~ ERROR: mismatched types
+
+    b"abc".iter().for_each(|x| dbg!(x)); //~ ERROR: mismatched types
+
+    b"abc".iter().for_each(|x| {
+        println!("{}", x);
+        x //~ ERROR: mismatched types
+    })
+}
diff --git a/tests/ui/typeck/closure-ty-mismatch-issue-128561.stderr b/tests/ui/typeck/closure-ty-mismatch-issue-128561.stderr
new file mode 100644
index 00000000000..31acc5bb10e
--- /dev/null
+++ b/tests/ui/typeck/closure-ty-mismatch-issue-128561.stderr
@@ -0,0 +1,28 @@
+error[E0308]: mismatched types
+  --> $DIR/closure-ty-mismatch-issue-128561.rs:2:32
+   |
+LL |     b"abc".iter().for_each(|x| x);
+   |                                ^ expected `()`, found `&u8`
+   |
+help: consider ignoring the value
+   |
+LL |     b"abc".iter().for_each(|x| _ = x);
+   |                                +++
+
+error[E0308]: mismatched types
+  --> $DIR/closure-ty-mismatch-issue-128561.rs:4:32
+   |
+LL |     b"abc".iter().for_each(|x| dbg!(x));
+   |                                ^^^^^^^ expected `()`, found `&u8`
+   |
+   = note: this error originates in the macro `dbg` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0308]: mismatched types
+  --> $DIR/closure-ty-mismatch-issue-128561.rs:8:9
+   |
+LL |         x
+   |         ^ expected `()`, found `&u8`
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/typeck/ice-unexpected-region-123863.stderr b/tests/ui/typeck/ice-unexpected-region-123863.stderr
index 8a4d767c143..e5050b4d316 100644
--- a/tests/ui/typeck/ice-unexpected-region-123863.stderr
+++ b/tests/ui/typeck/ice-unexpected-region-123863.stderr
@@ -39,7 +39,7 @@ LL |     Inner::concat_strs::<"a">::A
 help: if there were a trait named `Example` with associated type `concat_strs` implemented for `Inner<_>`, you could use the fully-qualified path
    |
 LL -     Inner::concat_strs::<"a">::A
-LL +     <Inner<_> as Example>::concat_strs::A
+LL +     <Inner<_> as Example>::concat_strs::<"a">::A
    |
 
 error: aborting due to 3 previous errors
diff --git a/tests/ui/typeck/issue-107087.stderr b/tests/ui/typeck/issue-107087.stderr
index 289c8d161ae..157ba5a1672 100644
--- a/tests/ui/typeck/issue-107087.stderr
+++ b/tests/ui/typeck/issue-107087.stderr
@@ -2,7 +2,13 @@ error[E0223]: ambiguous associated type
   --> $DIR/issue-107087.rs:16:5
    |
 LL |     A::B::<>::C
-   |     ^^^^^^^^ help: use fully-qualified syntax: `<A<_> as Foo>::B`
+   |     ^^^^^^^^
+   |
+help: use fully-qualified syntax
+   |
+LL -     A::B::<>::C
+LL +     <A<_> as Foo>::B::<>::C
+   |
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/unsafe-binders/non-strucutral-type-diag.rs b/tests/ui/unsafe-binders/non-strucutral-type-diag.rs
new file mode 100644
index 00000000000..e021e9567e5
--- /dev/null
+++ b/tests/ui/unsafe-binders/non-strucutral-type-diag.rs
@@ -0,0 +1,17 @@
+// regression test for <https://github.com/rust-lang/rust/issues/141422>.
+
+#![feature(unsafe_binders)]
+#![allow(incomplete_features)]
+
+#[derive(Copy, Clone)]
+struct Adt<'a>(&'a ());
+
+const C: Option<(unsafe<'a> Adt<'a>, Box<dyn Send>)> = None;
+
+fn main() {
+    match None {
+        C => {}
+        //~^ ERROR constant of non-structural type
+        _ => {}
+    }
+}
diff --git a/tests/ui/unsafe-binders/non-strucutral-type-diag.stderr b/tests/ui/unsafe-binders/non-strucutral-type-diag.stderr
new file mode 100644
index 00000000000..ab23210b2e5
--- /dev/null
+++ b/tests/ui/unsafe-binders/non-strucutral-type-diag.stderr
@@ -0,0 +1,13 @@
+error: constant of non-structural type `Option<(unsafe<'a> Adt<'a>, Box<dyn Send>)>` in a pattern
+  --> $DIR/non-strucutral-type-diag.rs:13:9
+   |
+LL | const C: Option<(unsafe<'a> Adt<'a>, Box<dyn Send>)> = None;
+   | ---------------------------------------------------- constant defined here
+...
+LL |         C => {}
+   |         ^ constant of non-structural type
+   |
+   = note: see https://doc.rust-lang.org/stable/std/marker/trait.StructuralPartialEq.html for details
+
+error: aborting due to 1 previous error
+
diff --git a/triagebot.toml b/triagebot.toml
index fd7a861bc92..9d7a0ef5aec 100644
--- a/triagebot.toml
+++ b/triagebot.toml
@@ -44,8 +44,6 @@ remove_labels = ["S-waiting-on-author"]
 # Those labels are added when PR author requests a review from an assignee
 add_labels = ["S-waiting-on-review"]
 
-[glacier]
-
 [ping.icebreakers-llvm]
 message = """\
 Hey LLVM ICE-breakers! This bug has been identified as a good
@@ -1425,3 +1423,12 @@ compiletest = [
 
 [behind-upstream]
 days-threshold = 14
+
+# Canonicalize issue numbers to avoid closing the wrong issue
+# when commits are included in subtrees, as well as warning links in commits.
+# Documentation at: https://forge.rust-lang.org/triagebot/issue-links.html
+[issue-links]
+
+# Prevents mentions in commits to avoid users being spammed
+# Documentation at: https://forge.rust-lang.org/triagebot/no-mentions.html
+[no-mentions]