diff --git a/compiler/rustc_builtin_macros/src/deriving/bounds.rs b/compiler/rustc_builtin_macros/src/deriving/bounds.rs
index a98e9c6d1c7fc..dd8f0e46a0e03 100644
--- a/compiler/rustc_builtin_macros/src/deriving/bounds.rs
+++ b/compiler/rustc_builtin_macros/src/deriving/bounds.rs
@@ -23,6 +23,7 @@ pub(crate) fn expand_deriving_copy(
         methods: Vec::new(),
         associated_types: Vec::new(),
         is_const,
+        is_staged_api_crate: cx.ecfg.features.staged_api(),
     };
 
     trait_def.expand(cx, mitem, item, push);
@@ -46,6 +47,7 @@ pub(crate) fn expand_deriving_const_param_ty(
         methods: Vec::new(),
         associated_types: Vec::new(),
         is_const,
+        is_staged_api_crate: cx.ecfg.features.staged_api(),
     };
 
     trait_def.expand(cx, mitem, item, push);
@@ -60,6 +62,7 @@ pub(crate) fn expand_deriving_const_param_ty(
         methods: Vec::new(),
         associated_types: Vec::new(),
         is_const,
+        is_staged_api_crate: cx.ecfg.features.staged_api(),
     };
 
     trait_def.expand(cx, mitem, item, push);
@@ -83,6 +86,7 @@ pub(crate) fn expand_deriving_unsized_const_param_ty(
         methods: Vec::new(),
         associated_types: Vec::new(),
         is_const,
+        is_staged_api_crate: cx.ecfg.features.staged_api(),
     };
 
     trait_def.expand(cx, mitem, item, push);
diff --git a/compiler/rustc_builtin_macros/src/deriving/clone.rs b/compiler/rustc_builtin_macros/src/deriving/clone.rs
index 69f8c273797e4..3c78f53c5cb0a 100644
--- a/compiler/rustc_builtin_macros/src/deriving/clone.rs
+++ b/compiler/rustc_builtin_macros/src/deriving/clone.rs
@@ -87,6 +87,7 @@ pub(crate) fn expand_deriving_clone(
         }],
         associated_types: Vec::new(),
         is_const,
+        is_staged_api_crate: cx.ecfg.features.staged_api(),
     };
 
     trait_def.expand_ext(cx, mitem, item, push, is_simple)
diff --git a/compiler/rustc_builtin_macros/src/deriving/cmp/eq.rs b/compiler/rustc_builtin_macros/src/deriving/cmp/eq.rs
index eca79e4dc4897..29d531219a69c 100644
--- a/compiler/rustc_builtin_macros/src/deriving/cmp/eq.rs
+++ b/compiler/rustc_builtin_macros/src/deriving/cmp/eq.rs
@@ -43,6 +43,7 @@ pub(crate) fn expand_deriving_eq(
         }],
         associated_types: Vec::new(),
         is_const,
+        is_staged_api_crate: cx.ecfg.features.staged_api(),
     };
     trait_def.expand_ext(cx, mitem, item, push, true)
 }
diff --git a/compiler/rustc_builtin_macros/src/deriving/cmp/ord.rs b/compiler/rustc_builtin_macros/src/deriving/cmp/ord.rs
index 1ed44c20bc61e..0e1ecf3118ac3 100644
--- a/compiler/rustc_builtin_macros/src/deriving/cmp/ord.rs
+++ b/compiler/rustc_builtin_macros/src/deriving/cmp/ord.rs
@@ -34,6 +34,7 @@ pub(crate) fn expand_deriving_ord(
         }],
         associated_types: Vec::new(),
         is_const,
+        is_staged_api_crate: cx.ecfg.features.staged_api(),
     };
 
     trait_def.expand(cx, mitem, item, push)
diff --git a/compiler/rustc_builtin_macros/src/deriving/cmp/partial_eq.rs b/compiler/rustc_builtin_macros/src/deriving/cmp/partial_eq.rs
index b1d950b8d89de..990835fa27739 100644
--- a/compiler/rustc_builtin_macros/src/deriving/cmp/partial_eq.rs
+++ b/compiler/rustc_builtin_macros/src/deriving/cmp/partial_eq.rs
@@ -30,6 +30,7 @@ pub(crate) fn expand_deriving_partial_eq(
         methods: Vec::new(),
         associated_types: Vec::new(),
         is_const: false,
+        is_staged_api_crate: cx.ecfg.features.staged_api(),
     };
     structural_trait_def.expand(cx, mitem, item, push);
 
@@ -58,6 +59,7 @@ pub(crate) fn expand_deriving_partial_eq(
         methods,
         associated_types: Vec::new(),
         is_const,
+        is_staged_api_crate: cx.ecfg.features.staged_api(),
     };
     trait_def.expand(cx, mitem, item, push)
 }
diff --git a/compiler/rustc_builtin_macros/src/deriving/cmp/partial_ord.rs b/compiler/rustc_builtin_macros/src/deriving/cmp/partial_ord.rs
index 0a076dd670b34..f5d262ece36e3 100644
--- a/compiler/rustc_builtin_macros/src/deriving/cmp/partial_ord.rs
+++ b/compiler/rustc_builtin_macros/src/deriving/cmp/partial_ord.rs
@@ -64,6 +64,7 @@ pub(crate) fn expand_deriving_partial_ord(
         methods: vec![partial_cmp_def],
         associated_types: Vec::new(),
         is_const,
+        is_staged_api_crate: cx.ecfg.features.staged_api(),
     };
     trait_def.expand(cx, mitem, item, push)
 }
diff --git a/compiler/rustc_builtin_macros/src/deriving/debug.rs b/compiler/rustc_builtin_macros/src/deriving/debug.rs
index 8ab21986e68a0..1d63ce7d5fd27 100644
--- a/compiler/rustc_builtin_macros/src/deriving/debug.rs
+++ b/compiler/rustc_builtin_macros/src/deriving/debug.rs
@@ -41,6 +41,7 @@ pub(crate) fn expand_deriving_debug(
         }],
         associated_types: Vec::new(),
         is_const,
+        is_staged_api_crate: cx.ecfg.features.staged_api(),
     };
     trait_def.expand(cx, mitem, item, push)
 }
diff --git a/compiler/rustc_builtin_macros/src/deriving/default.rs b/compiler/rustc_builtin_macros/src/deriving/default.rs
index 1fe567e23f455..b4e2d27fed333 100644
--- a/compiler/rustc_builtin_macros/src/deriving/default.rs
+++ b/compiler/rustc_builtin_macros/src/deriving/default.rs
@@ -51,6 +51,7 @@ pub(crate) fn expand_deriving_default(
         }],
         associated_types: Vec::new(),
         is_const,
+        is_staged_api_crate: cx.ecfg.features.staged_api(),
     };
     trait_def.expand(cx, mitem, item, push)
 }
diff --git a/compiler/rustc_builtin_macros/src/deriving/generic/mod.rs b/compiler/rustc_builtin_macros/src/deriving/generic/mod.rs
index c55a9e73e3822..b24e55637613a 100644
--- a/compiler/rustc_builtin_macros/src/deriving/generic/mod.rs
+++ b/compiler/rustc_builtin_macros/src/deriving/generic/mod.rs
@@ -181,9 +181,11 @@ use std::{iter, vec};
 pub(crate) use StaticFields::*;
 pub(crate) use SubstructureFields::*;
 use rustc_ast::ptr::P;
+use rustc_ast::token::{IdentIsRaw, LitKind, Token, TokenKind};
+use rustc_ast::tokenstream::{DelimSpan, Spacing, TokenTree};
 use rustc_ast::{
-    self as ast, AnonConst, BindingMode, ByRef, EnumDef, Expr, GenericArg, GenericParamKind,
-    Generics, Mutability, PatKind, VariantData,
+    self as ast, AnonConst, AttrArgs, BindingMode, ByRef, DelimArgs, EnumDef, Expr, GenericArg,
+    GenericParamKind, Generics, Mutability, PatKind, Safety, VariantData,
 };
 use rustc_attr_data_structures::{AttributeKind, ReprPacked};
 use rustc_attr_parsing::AttributeParser;
@@ -222,6 +224,8 @@ pub(crate) struct TraitDef<'a> {
     pub associated_types: Vec<(Ident, Ty)>,
 
     pub is_const: bool,
+
+    pub is_staged_api_crate: bool,
 }
 
 pub(crate) struct MethodDef<'a> {
@@ -784,8 +788,45 @@ impl<'a> TraitDef<'a> {
         // Create the type of `self`.
         let path = cx.path_all(self.span, false, vec![type_ident], self_params);
         let self_type = cx.ty_path(path);
+        let rustc_const_unstable =
+            cx.path_ident(self.span, Ident::new(sym::rustc_const_unstable, self.span));
+
+        let mut attrs = thin_vec![cx.attr_word(sym::automatically_derived, self.span),];
+
+        // Only add `rustc_const_unstable` attributes if `derive_const` is used within libcore/libstd,
+        // Other crates don't need stability attributes, so adding them is not useful, but libcore needs them
+        // on all const trait impls.
+        if self.is_const && self.is_staged_api_crate {
+            attrs.push(
+                cx.attr_nested(
+                    rustc_ast::AttrItem {
+                        unsafety: Safety::Default,
+                        path: rustc_const_unstable,
+                        args: AttrArgs::Delimited(DelimArgs {
+                            dspan: DelimSpan::from_single(self.span),
+                            delim: rustc_ast::token::Delimiter::Parenthesis,
+                            tokens: [
+                                TokenKind::Ident(sym::feature, IdentIsRaw::No),
+                                TokenKind::Eq,
+                                TokenKind::lit(LitKind::Str, sym::derive_const, None),
+                                TokenKind::Comma,
+                                TokenKind::Ident(sym::issue, IdentIsRaw::No),
+                                TokenKind::Eq,
+                                TokenKind::lit(LitKind::Str, sym::derive_const_issue, None),
+                            ]
+                            .into_iter()
+                            .map(|kind| {
+                                TokenTree::Token(Token { kind, span: self.span }, Spacing::Alone)
+                            })
+                            .collect(),
+                        }),
+                        tokens: None,
+                    },
+                    self.span,
+                ),
+            )
+        }
 
-        let attrs = thin_vec![cx.attr_word(sym::automatically_derived, self.span),];
         let opt_trait_ref = Some(trait_ref);
 
         cx.item(
diff --git a/compiler/rustc_builtin_macros/src/deriving/hash.rs b/compiler/rustc_builtin_macros/src/deriving/hash.rs
index 6e6dbe19e4d1a..78534449895c2 100644
--- a/compiler/rustc_builtin_macros/src/deriving/hash.rs
+++ b/compiler/rustc_builtin_macros/src/deriving/hash.rs
@@ -41,6 +41,7 @@ pub(crate) fn expand_deriving_hash(
         }],
         associated_types: Vec::new(),
         is_const,
+        is_staged_api_crate: cx.ecfg.features.staged_api(),
     };
 
     hash_trait_def.expand(cx, mitem, item, push);
diff --git a/compiler/rustc_expand/src/build.rs b/compiler/rustc_expand/src/build.rs
index 85683c1a03ff2..51d6e43ab6720 100644
--- a/compiler/rustc_expand/src/build.rs
+++ b/compiler/rustc_expand/src/build.rs
@@ -3,8 +3,8 @@ use rustc_ast::token::Delimiter;
 use rustc_ast::tokenstream::TokenStream;
 use rustc_ast::util::literal;
 use rustc_ast::{
-    self as ast, AnonConst, AttrVec, BlockCheckMode, Expr, LocalKind, MatchKind, PatKind, UnOp,
-    attr, token, tokenstream,
+    self as ast, AnonConst, AttrItem, AttrVec, BlockCheckMode, Expr, LocalKind, MatchKind, PatKind,
+    UnOp, attr, token, tokenstream,
 };
 use rustc_span::source_map::Spanned;
 use rustc_span::{DUMMY_SP, Ident, Span, Symbol, kw, sym};
@@ -766,4 +766,10 @@ impl<'a> ExtCtxt<'a> {
             span,
         )
     }
+
+    // Builds an attribute fully manually.
+    pub fn attr_nested(&self, inner: AttrItem, span: Span) -> ast::Attribute {
+        let g = &self.sess.psess.attr_id_generator;
+        attr::mk_attr_from_item(g, inner, None, ast::AttrStyle::Outer, span)
+    }
 }
diff --git a/compiler/rustc_hir_analysis/messages.ftl b/compiler/rustc_hir_analysis/messages.ftl
index a20becbe7e843..e38ca9e80cea9 100644
--- a/compiler/rustc_hir_analysis/messages.ftl
+++ b/compiler/rustc_hir_analysis/messages.ftl
@@ -158,7 +158,7 @@ hir_analysis_dispatch_from_dyn_zst = the trait `DispatchFromDyn` may only be imp
 hir_analysis_drop_impl_negative = negative `Drop` impls are not supported
 
 hir_analysis_drop_impl_on_wrong_item =
-    the `Drop` trait may only be implemented for local structs, enums, and unions
+    the `{$trait_}` trait may only be implemented for local structs, enums, and unions
     .label = must be a struct, enum, or union in the current crate
 
 hir_analysis_drop_impl_reservation = reservation `Drop` impls are not supported
diff --git a/compiler/rustc_hir_analysis/src/coherence/builtin.rs b/compiler/rustc_hir_analysis/src/coherence/builtin.rs
index 8356a0af63c35..27948f50a4ad5 100644
--- a/compiler/rustc_hir_analysis/src/coherence/builtin.rs
+++ b/compiler/rustc_hir_analysis/src/coherence/builtin.rs
@@ -37,6 +37,7 @@ pub(super) fn check_trait<'tcx>(
     let lang_items = tcx.lang_items();
     let checker = Checker { tcx, trait_def_id, impl_def_id, impl_header };
     checker.check(lang_items.drop_trait(), visit_implementation_of_drop)?;
+    checker.check(lang_items.async_drop_trait(), visit_implementation_of_drop)?;
     checker.check(lang_items.copy_trait(), visit_implementation_of_copy)?;
     checker.check(lang_items.const_param_ty_trait(), |checker| {
         visit_implementation_of_const_param_ty(checker, LangItem::ConstParamTy)
@@ -83,7 +84,10 @@ fn visit_implementation_of_drop(checker: &Checker<'_>) -> Result<(), ErrorGuaran
 
     let impl_ = tcx.hir_expect_item(impl_did).expect_impl();
 
-    Err(tcx.dcx().emit_err(errors::DropImplOnWrongItem { span: impl_.self_ty.span }))
+    Err(tcx.dcx().emit_err(errors::DropImplOnWrongItem {
+        span: impl_.self_ty.span,
+        trait_: tcx.item_name(checker.impl_header.trait_ref.skip_binder().def_id),
+    }))
 }
 
 fn visit_implementation_of_copy(checker: &Checker<'_>) -> Result<(), ErrorGuaranteed> {
diff --git a/compiler/rustc_hir_analysis/src/errors.rs b/compiler/rustc_hir_analysis/src/errors.rs
index eb65050c17c78..fbd21f8b10003 100644
--- a/compiler/rustc_hir_analysis/src/errors.rs
+++ b/compiler/rustc_hir_analysis/src/errors.rs
@@ -205,6 +205,7 @@ pub(crate) struct DropImplOnWrongItem {
     #[primary_span]
     #[label]
     pub span: Span,
+    pub trait_: Symbol,
 }
 
 #[derive(Diagnostic)]
diff --git a/compiler/rustc_hir_typeck/src/method/probe.rs b/compiler/rustc_hir_typeck/src/method/probe.rs
index 3261327a9fda9..1f3969bd93c3c 100644
--- a/compiler/rustc_hir_typeck/src/method/probe.rs
+++ b/compiler/rustc_hir_typeck/src/method/probe.rs
@@ -1650,7 +1650,8 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                 }
             }
 
-            let sources = candidates.iter().map(|p| self.candidate_source(p, self_ty)).collect();
+            let sources =
+                applicable_candidates.iter().map(|p| self.candidate_source(p.0, self_ty)).collect();
             return Some(Err(MethodError::Ambiguity(sources)));
         }
 
diff --git a/compiler/rustc_mir_transform/src/inline/cycle.rs b/compiler/rustc_mir_transform/src/inline/cycle.rs
index 93a81f0dca510..7f9234d1dc891 100644
--- a/compiler/rustc_mir_transform/src/inline/cycle.rs
+++ b/compiler/rustc_mir_transform/src/inline/cycle.rs
@@ -64,15 +64,15 @@ fn process<'tcx>(
     typing_env: ty::TypingEnv<'tcx>,
     caller: ty::Instance<'tcx>,
     target: LocalDefId,
-    seen: &mut FxHashSet<ty::Instance<'tcx>>,
+    seen: &mut FxHashMap<ty::Instance<'tcx>, bool>,
     involved: &mut FxHashSet<LocalDefId>,
     recursion_limiter: &mut FxHashMap<DefId, usize>,
     recursion_limit: Limit,
 ) -> bool {
     trace!(%caller);
-    let mut cycle_found = false;
+    let mut reaches_root = false;
 
-    for &(callee, args) in tcx.mir_inliner_callees(caller.def) {
+    for &(callee_def_id, args) in tcx.mir_inliner_callees(caller.def) {
         let Ok(args) = caller.try_instantiate_mir_and_normalize_erasing_regions(
             tcx,
             typing_env,
@@ -81,14 +81,17 @@ fn process<'tcx>(
             trace!(?caller, ?typing_env, ?args, "cannot normalize, skipping");
             continue;
         };
-        let Ok(Some(callee)) = ty::Instance::try_resolve(tcx, typing_env, callee, args) else {
-            trace!(?callee, "cannot resolve, skipping");
+        let Ok(Some(callee)) = ty::Instance::try_resolve(tcx, typing_env, callee_def_id, args)
+        else {
+            trace!(?callee_def_id, "cannot resolve, skipping");
             continue;
         };
 
         // Found a path.
         if callee.def_id() == target.to_def_id() {
-            cycle_found = true;
+            reaches_root = true;
+            seen.insert(callee, true);
+            continue;
         }
 
         if tcx.is_constructor(callee.def_id()) {
@@ -101,10 +104,17 @@ fn process<'tcx>(
             continue;
         }
 
-        if seen.insert(callee) {
+        let callee_reaches_root = if let Some(&c) = seen.get(&callee) {
+            // Even if we have seen this callee before, and thus don't need
+            // to recurse into it, we still need to propagate whether it reaches
+            // the root so that we can mark all the involved callers, in case we
+            // end up reaching that same recursive callee through some *other* cycle.
+            c
+        } else {
+            seen.insert(callee, false);
             let recursion = recursion_limiter.entry(callee.def_id()).or_default();
             trace!(?callee, recursion = *recursion);
-            let found_recursion = if recursion_limit.value_within_limit(*recursion) {
+            let callee_reaches_root = if recursion_limit.value_within_limit(*recursion) {
                 *recursion += 1;
                 ensure_sufficient_stack(|| {
                     process(
@@ -122,17 +132,19 @@ fn process<'tcx>(
                 // Pessimistically assume that there could be recursion.
                 true
             };
-            if found_recursion {
-                if let Some(callee) = callee.def_id().as_local() {
-                    // Calling `optimized_mir` of a non-local definition cannot cycle.
-                    involved.insert(callee);
-                }
-                cycle_found = true;
+            seen.insert(callee, callee_reaches_root);
+            callee_reaches_root
+        };
+        if callee_reaches_root {
+            if let Some(callee_def_id) = callee.def_id().as_local() {
+                // Calling `optimized_mir` of a non-local definition cannot cycle.
+                involved.insert(callee_def_id);
             }
+            reaches_root = true;
         }
     }
 
-    cycle_found
+    reaches_root
 }
 
 #[instrument(level = "debug", skip(tcx), ret)]
@@ -166,7 +178,7 @@ pub(crate) fn mir_callgraph_cyclic<'tcx>(
         typing_env,
         root_instance,
         root,
-        &mut FxHashSet::default(),
+        &mut FxHashMap::default(),
         &mut involved,
         &mut FxHashMap::default(),
         recursion_limit,
diff --git a/compiler/rustc_public/src/rustc_internal/mod.rs b/compiler/rustc_public/src/rustc_internal/mod.rs
index 5d7c8256d5bf0..01354fc7bd422 100644
--- a/compiler/rustc_public/src/rustc_internal/mod.rs
+++ b/compiler/rustc_public/src/rustc_internal/mod.rs
@@ -144,10 +144,10 @@ where
 #[macro_export]
 macro_rules! run {
     ($args:expr, $callback_fn:ident) => {
-        run_driver!($args, || $callback_fn())
+        $crate::run_driver!($args, || $callback_fn())
     };
     ($args:expr, $callback:expr) => {
-        run_driver!($args, $callback)
+        $crate::run_driver!($args, $callback)
     };
 }
 
@@ -158,10 +158,10 @@ macro_rules! run {
 #[macro_export]
 macro_rules! run_with_tcx {
     ($args:expr, $callback_fn:ident) => {
-        run_driver!($args, |tcx| $callback_fn(tcx), with_tcx)
+        $crate::run_driver!($args, |tcx| $callback_fn(tcx), with_tcx)
     };
     ($args:expr, $callback:expr) => {
-        run_driver!($args, $callback, with_tcx)
+        $crate::run_driver!($args, $callback, with_tcx)
     };
 }
 
@@ -191,11 +191,11 @@ macro_rules! run_driver {
         use rustc_public::CompilerError;
         use std::ops::ControlFlow;
 
-        pub struct StableMir<B = (), C = (), F = fn($(optional!($with_tcx TyCtxt))?) -> ControlFlow<B, C>>
+        pub struct StableMir<B = (), C = (), F = fn($($crate::optional!($with_tcx TyCtxt))?) -> ControlFlow<B, C>>
         where
             B: Send,
             C: Send,
-            F: FnOnce($(optional!($with_tcx TyCtxt))?) -> ControlFlow<B, C> + Send,
+            F: FnOnce($($crate::optional!($with_tcx TyCtxt))?) -> ControlFlow<B, C> + Send,
         {
             callback: Option<F>,
             result: Option<ControlFlow<B, C>>,
@@ -205,7 +205,7 @@ macro_rules! run_driver {
         where
             B: Send,
             C: Send,
-            F: FnOnce($(optional!($with_tcx TyCtxt))?) -> ControlFlow<B, C> + Send,
+            F: FnOnce($($crate::optional!($with_tcx TyCtxt))?) -> ControlFlow<B, C> + Send,
         {
             /// Creates a new `StableMir` instance, with given test_function and arguments.
             pub fn new(callback: F) -> Self {
@@ -240,7 +240,7 @@ macro_rules! run_driver {
         where
             B: Send,
             C: Send,
-            F: FnOnce($(optional!($with_tcx TyCtxt))?) -> ControlFlow<B, C> + Send,
+            F: FnOnce($($crate::optional!($with_tcx TyCtxt))?) -> ControlFlow<B, C> + Send,
         {
             /// Called after analysis. Return value instructs the compiler whether to
             /// continue the compilation afterwards (defaults to `Compilation::Continue`)
@@ -251,7 +251,7 @@ macro_rules! run_driver {
             ) -> Compilation {
                 if let Some(callback) = self.callback.take() {
                     rustc_internal::run(tcx, || {
-                        self.result = Some(callback($(optional!($with_tcx tcx))?));
+                        self.result = Some(callback($($crate::optional!($with_tcx tcx))?));
                     })
                     .unwrap();
                     if self.result.as_ref().is_some_and(|val| val.is_continue()) {
diff --git a/compiler/rustc_resolve/src/build_reduced_graph.rs b/compiler/rustc_resolve/src/build_reduced_graph.rs
index e56aabfd4144e..675ea9d1e98ee 100644
--- a/compiler/rustc_resolve/src/build_reduced_graph.rs
+++ b/compiler/rustc_resolve/src/build_reduced_graph.rs
@@ -49,8 +49,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         ns: Namespace,
         binding: NameBinding<'ra>,
     ) {
-        let key = self.new_disambiguated_key(ident, ns);
-        if let Err(old_binding) = self.try_define(parent, key, binding, false) {
+        if let Err(old_binding) = self.try_define(parent, ident, ns, binding, false) {
             self.report_conflict(parent, ident, ns, old_binding, binding);
         }
     }
@@ -442,16 +441,18 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
 
         self.r.indeterminate_imports.push(import);
         match import.kind {
-            // Don't add unresolved underscore imports to modules
-            ImportKind::Single { target: Ident { name: kw::Underscore, .. }, .. } => {}
             ImportKind::Single { target, type_ns_only, .. } => {
-                self.r.per_ns(|this, ns| {
-                    if !type_ns_only || ns == TypeNS {
-                        let key = BindingKey::new(target, ns);
-                        let mut resolution = this.resolution(current_module, key).borrow_mut();
-                        resolution.single_imports.insert(import);
-                    }
-                });
+                // Don't add underscore imports to `single_imports`
+                // because they cannot define any usable names.
+                if target.name != kw::Underscore {
+                    self.r.per_ns(|this, ns| {
+                        if !type_ns_only || ns == TypeNS {
+                            let key = BindingKey::new(target, ns);
+                            let mut resolution = this.resolution(current_module, key).borrow_mut();
+                            resolution.single_imports.insert(import);
+                        }
+                    });
+                }
             }
             // We don't add prelude imports to the globs since they only affect lexical scopes,
             // which are not relevant to import resolution.
@@ -1405,9 +1406,12 @@ impl<'a, 'ra, 'tcx> Visitor<'a> for BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
             let parent = self.parent_scope.module;
             let expansion = self.parent_scope.expansion;
             self.r.define(parent, ident, ns, self.res(def_id), vis, item.span, expansion);
-        } else if !matches!(&item.kind, AssocItemKind::Delegation(deleg) if deleg.from_glob) {
+        } else if !matches!(&item.kind, AssocItemKind::Delegation(deleg) if deleg.from_glob)
+            && ident.name != kw::Underscore
+        {
+            // Don't add underscore names, they cannot be looked up anyway.
             let impl_def_id = self.r.tcx.local_parent(local_def_id);
-            let key = BindingKey::new(ident.normalize_to_macros_2_0(), ns);
+            let key = BindingKey::new(ident, ns);
             self.r.impl_binding_keys.entry(impl_def_id).or_default().insert(key);
         }
 
diff --git a/compiler/rustc_resolve/src/imports.rs b/compiler/rustc_resolve/src/imports.rs
index 0a4c25b0eb052..b4c15ed1ca7e9 100644
--- a/compiler/rustc_resolve/src/imports.rs
+++ b/compiler/rustc_resolve/src/imports.rs
@@ -25,7 +25,7 @@ use rustc_span::{Ident, Span, Symbol, kw, sym};
 use smallvec::SmallVec;
 use tracing::debug;
 
-use crate::Namespace::*;
+use crate::Namespace::{self, *};
 use crate::diagnostics::{DiagMode, Suggestion, import_candidates};
 use crate::errors::{
     CannotBeReexportedCratePublic, CannotBeReexportedCratePublicNS, CannotBeReexportedPrivate,
@@ -338,13 +338,20 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
     pub(crate) fn try_define(
         &mut self,
         module: Module<'ra>,
-        key: BindingKey,
+        ident: Ident,
+        ns: Namespace,
         binding: NameBinding<'ra>,
         warn_ambiguity: bool,
     ) -> Result<(), NameBinding<'ra>> {
         let res = binding.res();
-        self.check_reserved_macro_name(key.ident, res);
+        self.check_reserved_macro_name(ident, res);
         self.set_binding_parent_module(binding, module);
+        // Even if underscore names cannot be looked up, we still need to add them to modules,
+        // because they can be fetched by glob imports from those modules, and bring traits
+        // into scope both directly and through glob imports.
+        let key = BindingKey::new_disambiguated(ident, ns, || {
+            (module.0.0.lazy_resolutions.borrow().len() + 1).try_into().unwrap()
+        });
         self.update_resolution(module, key, warn_ambiguity, |this, resolution| {
             if let Some(old_binding) = resolution.best_binding() {
                 if res == Res::Err && old_binding.res() != Res::Err {
@@ -383,7 +390,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     (old_glob @ true, false) | (old_glob @ false, true) => {
                         let (glob_binding, non_glob_binding) =
                             if old_glob { (old_binding, binding) } else { (binding, old_binding) };
-                        if key.ns == MacroNS
+                        if ns == MacroNS
                             && non_glob_binding.expansion != LocalExpnId::ROOT
                             && glob_binding.res() != non_glob_binding.res()
                         {
@@ -489,10 +496,10 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             };
             if self.is_accessible_from(binding.vis, scope) {
                 let imported_binding = self.import(binding, *import);
-                let key = BindingKey { ident, ..key };
                 let _ = self.try_define(
                     import.parent_scope.module,
-                    key,
+                    ident,
+                    key.ns,
                     imported_binding,
                     warn_ambiguity,
                 );
@@ -514,11 +521,15 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             let dummy_binding = self.dummy_binding;
             let dummy_binding = self.import(dummy_binding, import);
             self.per_ns(|this, ns| {
-                let key = BindingKey::new(target, ns);
-                let _ = this.try_define(import.parent_scope.module, key, dummy_binding, false);
-                this.update_resolution(import.parent_scope.module, key, false, |_, resolution| {
-                    resolution.single_imports.swap_remove(&import);
-                })
+                let module = import.parent_scope.module;
+                let _ = this.try_define(module, target, ns, dummy_binding, false);
+                // Don't remove underscores from `single_imports`, they were never added.
+                if target.name != kw::Underscore {
+                    let key = BindingKey::new(target, ns);
+                    this.update_resolution(module, key, false, |_, resolution| {
+                        resolution.single_imports.swap_remove(&import);
+                    })
+                }
             });
             self.record_use(target, dummy_binding, Used::Other);
         } else if import.imported_module.get().is_none() {
@@ -895,7 +906,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         PendingBinding::Ready(Some(imported_binding))
                     }
                     Err(Determinacy::Determined) => {
-                        // Don't update the resolution for underscores, because it was never added.
+                        // Don't remove underscores from `single_imports`, they were never added.
                         if target.name != kw::Underscore {
                             let key = BindingKey::new(target, ns);
                             this.update_resolution(parent, key, false, |_, resolution| {
@@ -1510,7 +1521,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     .is_some_and(|binding| binding.warn_ambiguity_recursive());
                 let _ = self.try_define(
                     import.parent_scope.module,
-                    key,
+                    key.ident,
+                    key.ns,
                     imported_binding,
                     warn_ambiguity,
                 );
diff --git a/compiler/rustc_resolve/src/late.rs b/compiler/rustc_resolve/src/late.rs
index 753b9365cd877..93cec8daa5a4a 100644
--- a/compiler/rustc_resolve/src/late.rs
+++ b/compiler/rustc_resolve/src/late.rs
@@ -2899,9 +2899,21 @@ impl<'a, 'ast, 'ra, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
                 }
 
                 if param.ident.name == kw::UnderscoreLifetime {
+                    // To avoid emitting two similar errors,
+                    // we need to check if the span is a raw underscore lifetime, see issue #143152
+                    let is_raw_underscore_lifetime = self
+                        .r
+                        .tcx
+                        .sess
+                        .psess
+                        .raw_identifier_spans
+                        .iter()
+                        .any(|span| span == param.span());
+
                     self.r
                         .dcx()
-                        .emit_err(errors::UnderscoreLifetimeIsReserved { span: param.ident.span });
+                        .create_err(errors::UnderscoreLifetimeIsReserved { span: param.ident.span })
+                        .emit_unless(is_raw_underscore_lifetime);
                     // Record lifetime res, so lowering knows there is something fishy.
                     self.record_lifetime_param(param.id, LifetimeRes::Error);
                     continue;
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index dae30b77ec1c3..f38fee8dea5d9 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -532,15 +532,26 @@ struct BindingKey {
     /// identifier.
     ident: Ident,
     ns: Namespace,
-    /// 0 if ident is not `_`, otherwise a value that's unique to the specific
-    /// `_` in the expanded AST that introduced this binding.
+    /// When we add an underscore binding (with ident `_`) to some module, this field has
+    /// a non-zero value that uniquely identifies this binding in that module.
+    /// For non-underscore bindings this field is zero.
+    /// When a key is constructed for name lookup (as opposed to name definition), this field is
+    /// also zero, even for underscore names, so for underscores the lookup will never succeed.
     disambiguator: u32,
 }
 
 impl BindingKey {
     fn new(ident: Ident, ns: Namespace) -> Self {
-        let ident = ident.normalize_to_macros_2_0();
-        BindingKey { ident, ns, disambiguator: 0 }
+        BindingKey { ident: ident.normalize_to_macros_2_0(), ns, disambiguator: 0 }
+    }
+
+    fn new_disambiguated(
+        ident: Ident,
+        ns: Namespace,
+        disambiguator: impl FnOnce() -> u32,
+    ) -> BindingKey {
+        let disambiguator = if ident.name == kw::Underscore { disambiguator() } else { 0 };
+        BindingKey { ident: ident.normalize_to_macros_2_0(), ns, disambiguator }
     }
 }
 
@@ -1087,8 +1098,6 @@ pub struct Resolver<'ra, 'tcx> {
     extern_module_map: RefCell<FxIndexMap<DefId, Module<'ra>>>,
     binding_parent_modules: FxHashMap<NameBinding<'ra>, Module<'ra>>,
 
-    underscore_disambiguator: u32,
-
     /// Maps glob imports to the names of items actually imported.
     glob_map: FxIndexMap<LocalDefId, FxIndexSet<Symbol>>,
     glob_error: Option<ErrorGuaranteed>,
@@ -1501,7 +1510,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             extern_crate_map: Default::default(),
             module_children: Default::default(),
             trait_map: NodeMap::default(),
-            underscore_disambiguator: 0,
             empty_module,
             local_module_map,
             extern_module_map: Default::default(),
@@ -1887,17 +1895,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         import_ids
     }
 
-    fn new_disambiguated_key(&mut self, ident: Ident, ns: Namespace) -> BindingKey {
-        let ident = ident.normalize_to_macros_2_0();
-        let disambiguator = if ident.name == kw::Underscore {
-            self.underscore_disambiguator += 1;
-            self.underscore_disambiguator
-        } else {
-            0
-        };
-        BindingKey { ident, ns, disambiguator }
-    }
-
     fn resolutions(&mut self, module: Module<'ra>) -> &'ra Resolutions<'ra> {
         if module.populate_on_access.get() {
             module.populate_on_access.set(false);
diff --git a/compiler/rustc_resolve/src/macros.rs b/compiler/rustc_resolve/src/macros.rs
index 77ef7f56c094c..0e8904a7deab6 100644
--- a/compiler/rustc_resolve/src/macros.rs
+++ b/compiler/rustc_resolve/src/macros.rs
@@ -530,7 +530,7 @@ impl<'ra, 'tcx> ResolverExpand for Resolver<'ra, 'tcx> {
         target_trait.for_each_child(self, |this, ident, ns, _binding| {
             // FIXME: Adjust hygiene for idents from globs, like for glob imports.
             if let Some(overriding_keys) = this.impl_binding_keys.get(&impl_def_id)
-                && overriding_keys.contains(&BindingKey::new(ident.normalize_to_macros_2_0(), ns))
+                && overriding_keys.contains(&BindingKey::new(ident, ns))
             {
                 // The name is overridden, do not produce it from the glob delegation.
             } else {
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 7147f37efc102..d28a73bc13978 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -840,6 +840,7 @@ symbols! {
         derive,
         derive_coerce_pointee,
         derive_const,
+        derive_const_issue: "118304",
         derive_default_enum,
         derive_smart_pointer,
         destruct,
diff --git a/library/alloc/src/fmt.rs b/library/alloc/src/fmt.rs
index 30f42050ac8ac..d0ba9c398864f 100644
--- a/library/alloc/src/fmt.rs
+++ b/library/alloc/src/fmt.rs
@@ -348,13 +348,13 @@
 //! format := '{' [ argument ] [ ':' format_spec ] [ ws ] * '}'
 //! argument := integer | identifier
 //!
-//! format_spec := [[fill]align][sign]['#']['0'][width]['.' precision]type
+//! format_spec := [[fill]align][sign]['#']['0'][width]['.' precision][type]
 //! fill := character
 //! align := '<' | '^' | '>'
 //! sign := '+' | '-'
 //! width := count
 //! precision := count | '*'
-//! type := '' | '?' | 'x?' | 'X?' | identifier
+//! type := '?' | 'x?' | 'X?' | identifier
 //! count := parameter | integer
 //! parameter := argument '$'
 //! ```
diff --git a/library/core/src/cmp.rs b/library/core/src/cmp.rs
index 03b120fbf0c34..6419ae9911359 100644
--- a/library/core/src/cmp.rs
+++ b/library/core/src/cmp.rs
@@ -381,7 +381,8 @@ pub struct AssertParamIsEq<T: Eq + PointeeSized> {
 ///
 /// assert_eq!(2.cmp(&1), Ordering::Greater);
 /// ```
-#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug, Hash)]
+#[derive(Clone, Copy, Eq, PartialOrd, Ord, Debug, Hash)]
+#[derive_const(PartialEq)]
 #[stable(feature = "rust1", since = "1.0.0")]
 // This is a lang item only so that `BinOp::Cmp` in MIR can return it.
 // It has no special behavior, but does require that the three variants
diff --git a/library/core/src/cmp/bytewise.rs b/library/core/src/cmp/bytewise.rs
index a06a5227fe285..7d61c9345ecf8 100644
--- a/library/core/src/cmp/bytewise.rs
+++ b/library/core/src/cmp/bytewise.rs
@@ -17,11 +17,15 @@ use crate::num::NonZero;
 /// - Neither `Self` nor `Rhs` have provenance, so integer comparisons are correct.
 /// - `<Self as PartialEq<Rhs>>::{eq,ne}` are equivalent to comparing the bytes.
 #[rustc_specialization_trait]
-pub(crate) unsafe trait BytewiseEq<Rhs = Self>: PartialEq<Rhs> + Sized {}
+#[const_trait]
+pub(crate) unsafe trait BytewiseEq<Rhs = Self>:
+    ~const PartialEq<Rhs> + Sized
+{
+}
 
 macro_rules! is_bytewise_comparable {
     ($($t:ty),+ $(,)?) => {$(
-        unsafe impl BytewiseEq for $t {}
+        unsafe impl const BytewiseEq for $t {}
     )+};
 }
 
diff --git a/library/core/src/intrinsics/mod.rs b/library/core/src/intrinsics/mod.rs
index fa27acac21721..f90e6851d1f5f 100644
--- a/library/core/src/intrinsics/mod.rs
+++ b/library/core/src/intrinsics/mod.rs
@@ -2208,6 +2208,7 @@ pub const unsafe fn raw_eq<T>(a: &T, b: &T) -> bool;
 /// [valid]: crate::ptr#safety
 #[rustc_nounwind]
 #[rustc_intrinsic]
+#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
 pub const unsafe fn compare_bytes(left: *const u8, right: *const u8, bytes: usize) -> i32;
 
 /// See documentation of [`std::hint::black_box`] for details.
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index e08edde3b38bb..729de5ffc8f6e 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -103,6 +103,7 @@
 #![feature(cfg_select)]
 #![feature(cfg_target_has_reliable_f16_f128)]
 #![feature(const_carrying_mul_add)]
+#![feature(const_cmp)]
 #![feature(const_destruct)]
 #![feature(const_eval_select)]
 #![feature(core_intrinsics)]
@@ -146,6 +147,7 @@
 #![feature(const_trait_impl)]
 #![feature(decl_macro)]
 #![feature(deprecated_suggestion)]
+#![feature(derive_const)]
 #![feature(doc_cfg)]
 #![feature(doc_cfg_hide)]
 #![feature(doc_notable_trait)]
diff --git a/library/core/src/macros/mod.rs b/library/core/src/macros/mod.rs
index 1b6dbc2f428f7..8ac6ce2242d4e 100644
--- a/library/core/src/macros/mod.rs
+++ b/library/core/src/macros/mod.rs
@@ -1615,7 +1615,7 @@ pub(crate) mod builtin {
     /// See [the reference] for more info.
     ///
     /// [the reference]: ../../../reference/attributes/derive.html
-    #[unstable(feature = "derive_const", issue = "none")]
+    #[unstable(feature = "derive_const", issue = "118304")]
     #[rustc_builtin_macro]
     pub macro derive_const($item:item) {
         /* compiler built-in */
diff --git a/library/core/src/num/nonzero.rs b/library/core/src/num/nonzero.rs
index 11d50e0f89f30..b8900c4113ad3 100644
--- a/library/core/src/num/nonzero.rs
+++ b/library/core/src/num/nonzero.rs
@@ -200,9 +200,10 @@ impl<T> UseCloned for NonZero<T> where T: ZeroablePrimitive {}
 impl<T> Copy for NonZero<T> where T: ZeroablePrimitive {}
 
 #[stable(feature = "nonzero", since = "1.28.0")]
-impl<T> PartialEq for NonZero<T>
+#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
+impl<T> const PartialEq for NonZero<T>
 where
-    T: ZeroablePrimitive + PartialEq,
+    T: ZeroablePrimitive + ~const PartialEq,
 {
     #[inline]
     fn eq(&self, other: &Self) -> bool {
diff --git a/library/core/src/option.rs b/library/core/src/option.rs
index 9f432758a66f6..da6e311ff5e1b 100644
--- a/library/core/src/option.rs
+++ b/library/core/src/option.rs
@@ -2243,7 +2243,8 @@ impl<'a, T> From<&'a mut Option<T>> for Option<&'a mut T> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> crate::marker::StructuralPartialEq for Option<T> {}
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T: PartialEq> PartialEq for Option<T> {
+#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
+impl<T: ~const PartialEq> const PartialEq for Option<T> {
     #[inline]
     fn eq(&self, other: &Self) -> bool {
         // Spelling out the cases explicitly optimizes better than
diff --git a/library/core/src/prelude/v1.rs b/library/core/src/prelude/v1.rs
index 7b9e04920d51d..a4be66b90cab3 100644
--- a/library/core/src/prelude/v1.rs
+++ b/library/core/src/prelude/v1.rs
@@ -80,7 +80,7 @@ pub use crate::macros::builtin::{
     alloc_error_handler, bench, derive, global_allocator, test, test_case,
 };
 
-#[unstable(feature = "derive_const", issue = "none")]
+#[unstable(feature = "derive_const", issue = "118304")]
 pub use crate::macros::builtin::derive_const;
 
 #[unstable(
diff --git a/library/core/src/slice/cmp.rs b/library/core/src/slice/cmp.rs
index 5ce72b46eee36..1eda8bc1bec40 100644
--- a/library/core/src/slice/cmp.rs
+++ b/library/core/src/slice/cmp.rs
@@ -8,9 +8,10 @@ use crate::num::NonZero;
 use crate::ops::ControlFlow;
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<T, U> PartialEq<[U]> for [T]
+#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
+impl<T, U> const PartialEq<[U]> for [T]
 where
-    T: PartialEq<U>,
+    T: ~const PartialEq<U>,
 {
     fn eq(&self, other: &[U]) -> bool {
         SlicePartialEq::equal(self, other)
@@ -94,6 +95,8 @@ impl<T: PartialOrd> PartialOrd for [T] {
 
 #[doc(hidden)]
 // intermediate trait for specialization of slice's PartialEq
+#[const_trait]
+#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
 trait SlicePartialEq<B> {
     fn equal(&self, other: &[B]) -> bool;
 
@@ -103,9 +106,10 @@ trait SlicePartialEq<B> {
 }
 
 // Generic slice equality
-impl<A, B> SlicePartialEq<B> for [A]
+#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
+impl<A, B> const SlicePartialEq<B> for [A]
 where
-    A: PartialEq<B>,
+    A: ~const PartialEq<B>,
 {
     default fn equal(&self, other: &[B]) -> bool {
         if self.len() != other.len() {
@@ -115,11 +119,14 @@ where
         // Implemented as explicit indexing rather
         // than zipped iterators for performance reasons.
         // See PR https://github.com/rust-lang/rust/pull/116846
-        for idx in 0..self.len() {
+        // FIXME(const_hack): make this a `for idx in 0..self.len()` loop.
+        let mut idx = 0;
+        while idx < self.len() {
             // bound checks are optimized away
             if self[idx] != other[idx] {
                 return false;
             }
+            idx += 1;
         }
 
         true
@@ -128,9 +135,10 @@ where
 
 // When each element can be compared byte-wise, we can compare all the bytes
 // from the whole size in one call to the intrinsics.
-impl<A, B> SlicePartialEq<B> for [A]
+#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
+impl<A, B> const SlicePartialEq<B> for [A]
 where
-    A: BytewiseEq<B>,
+    A: ~const BytewiseEq<B>,
 {
     fn equal(&self, other: &[B]) -> bool {
         if self.len() != other.len() {
diff --git a/library/core/src/str/traits.rs b/library/core/src/str/traits.rs
index 42ffc591b5bbf..d0f2b9226bf6d 100644
--- a/library/core/src/str/traits.rs
+++ b/library/core/src/str/traits.rs
@@ -23,7 +23,8 @@ impl Ord for str {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl PartialEq for str {
+#[rustc_const_unstable(feature = "const_cmp", issue = "143800")]
+impl const PartialEq for str {
     #[inline]
     fn eq(&self, other: &str) -> bool {
         self.as_bytes() == other.as_bytes()
diff --git a/library/std/src/prelude/v1.rs b/library/std/src/prelude/v1.rs
index 69f0335315356..70c1113155656 100644
--- a/library/std/src/prelude/v1.rs
+++ b/library/std/src/prelude/v1.rs
@@ -67,7 +67,7 @@ pub use core::prelude::v1::{
     alloc_error_handler, bench, derive, global_allocator, test, test_case,
 };
 
-#[unstable(feature = "derive_const", issue = "none")]
+#[unstable(feature = "derive_const", issue = "118304")]
 pub use core::prelude::v1::derive_const;
 
 // Do not `doc(no_inline)` either.
diff --git a/src/ci/github-actions/jobs.yml b/src/ci/github-actions/jobs.yml
index 6c5e37b51ef23..f0c52fe3d1ca0 100644
--- a/src/ci/github-actions/jobs.yml
+++ b/src/ci/github-actions/jobs.yml
@@ -34,6 +34,8 @@ runners:
     os: windows-2022
     <<: *base-job
 
+  # NOTE: windows-2025 has less disk space available than windows-2022,
+  # because the D drive is missing.
   - &job-windows-25
     os: windows-2025
     <<: *base-job
@@ -542,13 +544,13 @@ auto:
     env:
       RUST_CONFIGURE_ARGS: --build=x86_64-pc-windows-msvc --enable-sanitizers --enable-profiler
       SCRIPT: make ci-msvc-py
-    <<: *job-windows-25
+    <<: *job-windows
 
   - name: x86_64-msvc-2
     env:
       RUST_CONFIGURE_ARGS: --build=x86_64-pc-windows-msvc --enable-sanitizers --enable-profiler
       SCRIPT: make ci-msvc-ps1
-    <<: *job-windows-25
+    <<: *job-windows
 
   # i686-msvc is split into two jobs to run tests in parallel.
   - name: i686-msvc-1
diff --git a/tests/mir-opt/inline_double_cycle.a.Inline.panic-unwind.diff b/tests/mir-opt/inline_double_cycle.a.Inline.panic-unwind.diff
new file mode 100644
index 0000000000000..55da685a3d430
--- /dev/null
+++ b/tests/mir-opt/inline_double_cycle.a.Inline.panic-unwind.diff
@@ -0,0 +1,48 @@
+- // MIR for `a` before Inline
++ // MIR for `a` after Inline
+  
+  fn a() -> () {
+      let mut _0: ();
+      let _1: ();
+      let mut _2: ();
+      let _3: ();
+      let mut _4: ();
++     let mut _5: fn() {a};
++     let mut _6: fn() {b};
++     scope 1 (inlined <fn() {a} as FnOnce<()>>::call_once - shim(fn() {a})) {
++     }
++     scope 2 (inlined <fn() {b} as FnOnce<()>>::call_once - shim(fn() {b})) {
++     }
+  
+      bb0: {
+          StorageLive(_1);
+          StorageLive(_2);
+          _2 = ();
+-         _1 = <fn() {a} as FnOnce<()>>::call_once(a, move _2) -> [return: bb1, unwind continue];
++         StorageLive(_5);
++         _5 = a;
++         _1 = move _5() -> [return: bb1, unwind continue];
+      }
+  
+      bb1: {
++         StorageDead(_5);
+          StorageDead(_2);
+          StorageDead(_1);
+          StorageLive(_3);
+          StorageLive(_4);
+          _4 = ();
+-         _3 = <fn() {b} as FnOnce<()>>::call_once(b, move _4) -> [return: bb2, unwind continue];
++         StorageLive(_6);
++         _6 = b;
++         _3 = move _6() -> [return: bb2, unwind continue];
+      }
+  
+      bb2: {
++         StorageDead(_6);
+          StorageDead(_4);
+          StorageDead(_3);
+          _0 = const ();
+          return;
+      }
+  }
+  
diff --git a/tests/mir-opt/inline_double_cycle.b.Inline.panic-unwind.diff b/tests/mir-opt/inline_double_cycle.b.Inline.panic-unwind.diff
new file mode 100644
index 0000000000000..9e6eef1fa3049
--- /dev/null
+++ b/tests/mir-opt/inline_double_cycle.b.Inline.panic-unwind.diff
@@ -0,0 +1,48 @@
+- // MIR for `b` before Inline
++ // MIR for `b` after Inline
+  
+  fn b() -> () {
+      let mut _0: ();
+      let _1: ();
+      let mut _2: ();
+      let _3: ();
+      let mut _4: ();
++     let mut _5: fn() {b};
++     let mut _6: fn() {a};
++     scope 1 (inlined <fn() {b} as FnOnce<()>>::call_once - shim(fn() {b})) {
++     }
++     scope 2 (inlined <fn() {a} as FnOnce<()>>::call_once - shim(fn() {a})) {
++     }
+  
+      bb0: {
+          StorageLive(_1);
+          StorageLive(_2);
+          _2 = ();
+-         _1 = <fn() {b} as FnOnce<()>>::call_once(b, move _2) -> [return: bb1, unwind continue];
++         StorageLive(_5);
++         _5 = b;
++         _1 = move _5() -> [return: bb1, unwind continue];
+      }
+  
+      bb1: {
++         StorageDead(_5);
+          StorageDead(_2);
+          StorageDead(_1);
+          StorageLive(_3);
+          StorageLive(_4);
+          _4 = ();
+-         _3 = <fn() {a} as FnOnce<()>>::call_once(a, move _4) -> [return: bb2, unwind continue];
++         StorageLive(_6);
++         _6 = a;
++         _3 = move _6() -> [return: bb2, unwind continue];
+      }
+  
+      bb2: {
++         StorageDead(_6);
+          StorageDead(_4);
+          StorageDead(_3);
+          _0 = const ();
+          return;
+      }
+  }
+  
diff --git a/tests/mir-opt/inline_double_cycle.rs b/tests/mir-opt/inline_double_cycle.rs
new file mode 100644
index 0000000000000..cf3b87cf0ad30
--- /dev/null
+++ b/tests/mir-opt/inline_double_cycle.rs
@@ -0,0 +1,22 @@
+// EMIT_MIR_FOR_EACH_PANIC_STRATEGY
+// skip-filecheck
+//@ test-mir-pass: Inline
+//@ edition: 2021
+//@ compile-flags: -Zinline-mir --crate-type=lib
+
+// EMIT_MIR inline_double_cycle.a.Inline.diff
+// EMIT_MIR inline_double_cycle.b.Inline.diff
+
+#![feature(fn_traits)]
+
+#[inline]
+pub fn a() {
+    FnOnce::call_once(a, ());
+    FnOnce::call_once(b, ());
+}
+
+#[inline]
+pub fn b() {
+    FnOnce::call_once(b, ());
+    FnOnce::call_once(a, ());
+}
diff --git a/tests/ui/async-await/async-drop/foreign-fundamental.rs b/tests/ui/async-await/async-drop/foreign-fundamental.rs
new file mode 100644
index 0000000000000..1c192fccd9f0c
--- /dev/null
+++ b/tests/ui/async-await/async-drop/foreign-fundamental.rs
@@ -0,0 +1,21 @@
+//@ edition: 2018
+
+#![feature(async_drop)]
+//~^ WARN the feature `async_drop` is incomplete
+
+use std::future::AsyncDrop;
+use std::pin::Pin;
+
+struct Foo;
+
+impl AsyncDrop for &Foo {
+    //~^ ERROR the `AsyncDrop` trait may only be implemented for
+    async fn drop(self: Pin<&mut Self>) {}
+}
+
+impl AsyncDrop for Pin<Foo> {
+    //~^ ERROR the `AsyncDrop` trait may only be implemented for
+    async fn drop(self: Pin<&mut Self>) {}
+}
+
+fn main() {}
diff --git a/tests/ui/async-await/async-drop/foreign-fundamental.stderr b/tests/ui/async-await/async-drop/foreign-fundamental.stderr
new file mode 100644
index 0000000000000..7b52329ac99d1
--- /dev/null
+++ b/tests/ui/async-await/async-drop/foreign-fundamental.stderr
@@ -0,0 +1,24 @@
+warning: the feature `async_drop` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/foreign-fundamental.rs:3:12
+   |
+LL | #![feature(async_drop)]
+   |            ^^^^^^^^^^
+   |
+   = note: see issue #126482 <https://github.com/rust-lang/rust/issues/126482> for more information
+   = note: `#[warn(incomplete_features)]` on by default
+
+error[E0120]: the `AsyncDrop` trait may only be implemented for local structs, enums, and unions
+  --> $DIR/foreign-fundamental.rs:11:20
+   |
+LL | impl AsyncDrop for &Foo {
+   |                    ^^^^ must be a struct, enum, or union in the current crate
+
+error[E0120]: the `AsyncDrop` trait may only be implemented for local structs, enums, and unions
+  --> $DIR/foreign-fundamental.rs:16:20
+   |
+LL | impl AsyncDrop for Pin<Foo> {
+   |                    ^^^^^^^^ must be a struct, enum, or union in the current crate
+
+error: aborting due to 2 previous errors; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0120`.
diff --git a/tests/ui/consts/const-compare-bytes-ub.rs b/tests/ui/consts/const-compare-bytes-ub.rs
index 0bc8585a4eed1..7e3df92a2bf5a 100644
--- a/tests/ui/consts/const-compare-bytes-ub.rs
+++ b/tests/ui/consts/const-compare-bytes-ub.rs
@@ -1,6 +1,6 @@
 //@ check-fail
 
-#![feature(core_intrinsics)]
+#![feature(core_intrinsics, const_cmp)]
 use std::intrinsics::compare_bytes;
 use std::mem::MaybeUninit;
 
diff --git a/tests/ui/consts/const-compare-bytes.rs b/tests/ui/consts/const-compare-bytes.rs
index cd5cdfd0400ec..9563375555cfd 100644
--- a/tests/ui/consts/const-compare-bytes.rs
+++ b/tests/ui/consts/const-compare-bytes.rs
@@ -1,6 +1,6 @@
 //@ run-pass
 
-#![feature(core_intrinsics)]
+#![feature(core_intrinsics, const_cmp)]
 use std::intrinsics::compare_bytes;
 
 fn main() {
diff --git a/tests/ui/consts/const-eval/auxiliary/stability.rs b/tests/ui/consts/const-eval/auxiliary/stability.rs
index e615955186020..48ced3bc51e62 100644
--- a/tests/ui/consts/const-eval/auxiliary/stability.rs
+++ b/tests/ui/consts/const-eval/auxiliary/stability.rs
@@ -1,10 +1,11 @@
 // Crate that exports a const fn. Used for testing cross-crate.
 
-#![crate_type="rlib"]
+#![crate_type = "rlib"]
 #![stable(feature = "rust1", since = "1.0.0")]
-
 #![feature(staged_api)]
 
 #[stable(feature = "rust1", since = "1.0.0")]
-#[rustc_const_unstable(feature="foo", issue = "none")]
-pub const fn foo() -> u32 { 42 }
+#[rustc_const_unstable(feature = "foo", issue = "none")]
+pub const fn foo() -> u32 {
+    42
+}
diff --git a/tests/ui/deduplicate-diagnostics.deduplicate.stderr b/tests/ui/diagnostic-flags/deduplicate-diagnostics.deduplicate.stderr
similarity index 80%
rename from tests/ui/deduplicate-diagnostics.deduplicate.stderr
rename to tests/ui/diagnostic-flags/deduplicate-diagnostics.deduplicate.stderr
index 5df2c687bddc2..c0d568eb5384e 100644
--- a/tests/ui/deduplicate-diagnostics.deduplicate.stderr
+++ b/tests/ui/diagnostic-flags/deduplicate-diagnostics.deduplicate.stderr
@@ -1,11 +1,11 @@
 error[E0452]: malformed lint attribute input
-  --> $DIR/deduplicate-diagnostics.rs:8:8
+  --> $DIR/deduplicate-diagnostics.rs:10:8
    |
 LL | #[deny("literal")]
    |        ^^^^^^^^^ bad attribute argument
 
 error: cannot find derive macro `Unresolved` in this scope
-  --> $DIR/deduplicate-diagnostics.rs:4:10
+  --> $DIR/deduplicate-diagnostics.rs:6:10
    |
 LL | #[derive(Unresolved)]
    |          ^^^^^^^^^^
diff --git a/tests/ui/deduplicate-diagnostics.duplicate.stderr b/tests/ui/diagnostic-flags/deduplicate-diagnostics.duplicate.stderr
similarity index 81%
rename from tests/ui/deduplicate-diagnostics.duplicate.stderr
rename to tests/ui/diagnostic-flags/deduplicate-diagnostics.duplicate.stderr
index 48e2ba7b86aa4..74d7066293f30 100644
--- a/tests/ui/deduplicate-diagnostics.duplicate.stderr
+++ b/tests/ui/diagnostic-flags/deduplicate-diagnostics.duplicate.stderr
@@ -1,17 +1,17 @@
 error[E0452]: malformed lint attribute input
-  --> $DIR/deduplicate-diagnostics.rs:8:8
+  --> $DIR/deduplicate-diagnostics.rs:10:8
    |
 LL | #[deny("literal")]
    |        ^^^^^^^^^ bad attribute argument
 
 error: cannot find derive macro `Unresolved` in this scope
-  --> $DIR/deduplicate-diagnostics.rs:4:10
+  --> $DIR/deduplicate-diagnostics.rs:6:10
    |
 LL | #[derive(Unresolved)]
    |          ^^^^^^^^^^
 
 error: cannot find derive macro `Unresolved` in this scope
-  --> $DIR/deduplicate-diagnostics.rs:4:10
+  --> $DIR/deduplicate-diagnostics.rs:6:10
    |
 LL | #[derive(Unresolved)]
    |          ^^^^^^^^^^
@@ -19,7 +19,7 @@ LL | #[derive(Unresolved)]
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error[E0452]: malformed lint attribute input
-  --> $DIR/deduplicate-diagnostics.rs:8:8
+  --> $DIR/deduplicate-diagnostics.rs:10:8
    |
 LL | #[deny("literal")]
    |        ^^^^^^^^^ bad attribute argument
@@ -27,7 +27,7 @@ LL | #[deny("literal")]
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error[E0452]: malformed lint attribute input
-  --> $DIR/deduplicate-diagnostics.rs:8:8
+  --> $DIR/deduplicate-diagnostics.rs:10:8
    |
 LL | #[deny("literal")]
    |        ^^^^^^^^^ bad attribute argument
diff --git a/tests/ui/deduplicate-diagnostics.rs b/tests/ui/diagnostic-flags/deduplicate-diagnostics.rs
similarity index 84%
rename from tests/ui/deduplicate-diagnostics.rs
rename to tests/ui/diagnostic-flags/deduplicate-diagnostics.rs
index 299c1f5f46108..48705266e3584 100644
--- a/tests/ui/deduplicate-diagnostics.rs
+++ b/tests/ui/diagnostic-flags/deduplicate-diagnostics.rs
@@ -1,3 +1,5 @@
+//! Test that `-Z deduplicate-diagnostics` flag properly deduplicates diagnostic messages.
+
 //@ revisions: duplicate deduplicate
 //@[deduplicate] compile-flags: -Z deduplicate-diagnostics=yes
 
diff --git a/tests/ui/error-codes/E0120.rs b/tests/ui/error-codes/E0120.rs
index 35f544fddfbfc..4e5cc7d6833b1 100644
--- a/tests/ui/error-codes/E0120.rs
+++ b/tests/ui/error-codes/E0120.rs
@@ -1,4 +1,4 @@
-trait MyTrait { fn foo() {} }
+trait MyTrait { fn foo(&self) {} }
 
 impl Drop for dyn MyTrait {
               //~^ ERROR E0120
diff --git a/tests/ui/expr/syntax-edge-cases-lint-clean.rs b/tests/ui/expr/weird-exprs.rs
similarity index 100%
rename from tests/ui/expr/syntax-edge-cases-lint-clean.rs
rename to tests/ui/expr/weird-exprs.rs
diff --git a/tests/ui/log-poly.rs b/tests/ui/fmt/println-debug-different-types.rs
similarity index 72%
rename from tests/ui/log-poly.rs
rename to tests/ui/fmt/println-debug-different-types.rs
index 64994a558174c..9e21be1f03fca 100644
--- a/tests/ui/log-poly.rs
+++ b/tests/ui/fmt/println-debug-different-types.rs
@@ -1,8 +1,10 @@
+//! Smoke test for println!() with debug format specifiers.
+
 //@ run-pass
 
 #[derive(Debug)]
 enum Numbers {
-    Three
+    Three,
 }
 
 pub fn main() {
diff --git a/tests/ui/impl-trait/call_method_without_import.no_import.stderr b/tests/ui/impl-trait/call_method_without_import.no_import.stderr
index e59409ea27e64..dbac74b224793 100644
--- a/tests/ui/impl-trait/call_method_without_import.no_import.stderr
+++ b/tests/ui/impl-trait/call_method_without_import.no_import.stderr
@@ -22,15 +22,10 @@ LL |         x.fmt(f);
    = help: items from traits can only be used if the trait is in scope
 help: the following traits which provide `fmt` are implemented but not in scope; perhaps you want to import one of them
    |
-LL + use std::fmt::Binary;
-   |
 LL + use std::fmt::Debug;
    |
-LL + use std::fmt::Display;
-   |
-LL + use std::fmt::LowerExp;
+LL + use std::fmt::Pointer;
    |
-   = and 5 other candidates
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/impl-trait/no-method-suggested-traits.stderr b/tests/ui/impl-trait/no-method-suggested-traits.stderr
index 061c9bd8f3501..b376f205411c6 100644
--- a/tests/ui/impl-trait/no-method-suggested-traits.stderr
+++ b/tests/ui/impl-trait/no-method-suggested-traits.stderr
@@ -9,12 +9,8 @@ help: the following traits which provide `method` are implemented but not in sco
    |
 LL + use foo::Bar;
    |
-LL + use no_method_suggested_traits::Reexported;
-   |
 LL + use no_method_suggested_traits::foo::PubPub;
    |
-LL + use no_method_suggested_traits::qux::PrivPub;
-   |
 help: there is a method `method2` with a similar name
    |
 LL |     1u32.method2();
@@ -31,12 +27,8 @@ help: the following traits which provide `method` are implemented but not in sco
    |
 LL + use foo::Bar;
    |
-LL + use no_method_suggested_traits::Reexported;
-   |
 LL + use no_method_suggested_traits::foo::PubPub;
    |
-LL + use no_method_suggested_traits::qux::PrivPub;
-   |
 help: there is a method `method2` with a similar name
    |
 LL |     std::rc::Rc::new(&mut Box::new(&1u32)).method2();
diff --git a/tests/ui/darwin-ld64.rs b/tests/ui/linking/ld64-cross-compilation.rs
similarity index 71%
rename from tests/ui/darwin-ld64.rs
rename to tests/ui/linking/ld64-cross-compilation.rs
index 75acc07a002c4..d6c6d1ff91def 100644
--- a/tests/ui/darwin-ld64.rs
+++ b/tests/ui/linking/ld64-cross-compilation.rs
@@ -1,11 +1,11 @@
+//! This is a regression test for https://github.com/rust-lang/rust/issues/140686.
+//! Although this is a ld64(ld-classic) bug, we still need to support it
+//! due to cross-compilation and support for older Xcode.
+
 //@ compile-flags: -Copt-level=3 -Ccodegen-units=256 -Clink-arg=-ld_classic
 //@ run-pass
 //@ only-x86_64-apple-darwin
 
-// This is a regression test for https://github.com/rust-lang/rust/issues/140686.
-// Although this is a ld64(ld-classic) bug, we still need to support it
-// due to cross-compilation and support for older Xcode.
-
 fn main() {
     let dst: Vec<u8> = Vec::new();
     let len = broken_func(std::hint::black_box(2), dst);
diff --git a/tests/ui/methods/method-deref-to-same-trait-object-with-separate-params.stderr b/tests/ui/methods/method-deref-to-same-trait-object-with-separate-params.stderr
index 32cff62284e09..aeecb82e9d910 100644
--- a/tests/ui/methods/method-deref-to-same-trait-object-with-separate-params.stderr
+++ b/tests/ui/methods/method-deref-to-same-trait-object-with-separate-params.stderr
@@ -20,17 +20,12 @@ error[E0034]: multiple applicable items in scope
 LL |     let z = x.foo();
    |               ^^^ multiple `foo` found
    |
-note: candidate #1 is defined in the trait `FinalFoo`
-  --> $DIR/method-deref-to-same-trait-object-with-separate-params.rs:60:5
-   |
-LL |     fn foo(&self) -> u8;
-   |     ^^^^^^^^^^^^^^^^^^^^
-note: candidate #2 is defined in an impl of the trait `NuisanceFoo` for the type `T`
+note: candidate #1 is defined in an impl of the trait `NuisanceFoo` for the type `T`
   --> $DIR/method-deref-to-same-trait-object-with-separate-params.rs:73:9
    |
 LL |         fn foo(self) {}
    |         ^^^^^^^^^^^^
-note: candidate #3 is defined in an impl of the trait `X` for the type `T`
+note: candidate #2 is defined in an impl of the trait `X` for the type `T`
   --> $DIR/method-deref-to-same-trait-object-with-separate-params.rs:46:9
    |
 LL |         fn foo(self: Smaht<Self, u64>) -> u64 {
@@ -38,14 +33,9 @@ LL |         fn foo(self: Smaht<Self, u64>) -> u64 {
 help: disambiguate the method for candidate #1
    |
 LL -     let z = x.foo();
-LL +     let z = FinalFoo::foo(&x);
-   |
-help: disambiguate the method for candidate #2
-   |
-LL -     let z = x.foo();
 LL +     let z = NuisanceFoo::foo(x);
    |
-help: disambiguate the method for candidate #3
+help: disambiguate the method for candidate #2
    |
 LL -     let z = x.foo();
 LL +     let z = X::foo(x);
diff --git a/tests/ui/methods/wrong-ambig-message.rs b/tests/ui/methods/wrong-ambig-message.rs
new file mode 100644
index 0000000000000..f88d77e259d68
--- /dev/null
+++ b/tests/ui/methods/wrong-ambig-message.rs
@@ -0,0 +1,34 @@
+fn main() {
+    trait Hello {
+        fn name(&self) -> String;
+    }
+
+    #[derive(Debug)]
+    struct Container2 {
+        val: String,
+    }
+
+    trait AName2 {
+        fn name(&self) -> String;
+    }
+
+    trait BName2 {
+        fn name(&self, v: bool) -> String;
+    }
+
+    impl AName2 for Container2 {
+        fn name(&self) -> String {
+            "aname2".into()
+        }
+    }
+
+    impl BName2 for Container2 {
+        fn name(&self, _v: bool) -> String {
+            "bname2".into()
+        }
+    }
+
+    let c2 = Container2 { val: "abc".into() };
+    println!("c2 = {:?}", c2.name());
+    //~^ ERROR: multiple applicable items in scope
+}
diff --git a/tests/ui/methods/wrong-ambig-message.stderr b/tests/ui/methods/wrong-ambig-message.stderr
new file mode 100644
index 0000000000000..9a254595e40bc
--- /dev/null
+++ b/tests/ui/methods/wrong-ambig-message.stderr
@@ -0,0 +1,30 @@
+error[E0034]: multiple applicable items in scope
+  --> $DIR/wrong-ambig-message.rs:32:30
+   |
+LL |     println!("c2 = {:?}", c2.name());
+   |                              ^^^^ multiple `name` found
+   |
+note: candidate #1 is defined in an impl of the trait `AName2` for the type `Container2`
+  --> $DIR/wrong-ambig-message.rs:20:9
+   |
+LL |         fn name(&self) -> String {
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^
+note: candidate #2 is defined in an impl of the trait `BName2` for the type `Container2`
+  --> $DIR/wrong-ambig-message.rs:26:9
+   |
+LL |         fn name(&self, _v: bool) -> String {
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+help: disambiguate the method for candidate #1
+   |
+LL -     println!("c2 = {:?}", c2.name());
+LL +     println!("c2 = {:?}", AName2::name(&c2));
+   |
+help: disambiguate the method for candidate #2
+   |
+LL -     println!("c2 = {:?}", c2.name());
+LL +     println!("c2 = {:?}", BName2::name(&c2));
+   |
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0034`.
diff --git a/tests/ui/lexical-scopes.rs b/tests/ui/shadowed/shadowing-generic-item.rs
similarity index 76%
rename from tests/ui/lexical-scopes.rs
rename to tests/ui/shadowed/shadowing-generic-item.rs
index 46cfdf1efa8f0..c3a0ced04e7f0 100644
--- a/tests/ui/lexical-scopes.rs
+++ b/tests/ui/shadowed/shadowing-generic-item.rs
@@ -1,3 +1,5 @@
+//! Test that generic parameters shadow structs and modules with the same name.
+
 struct T { i: i32 }
 fn f<T>() {
     let t = T { i: 0 }; //~ ERROR expected struct, variant or union type, found type parameter `T`
diff --git a/tests/ui/lexical-scopes.stderr b/tests/ui/shadowed/shadowing-generic-item.stderr
similarity index 89%
rename from tests/ui/lexical-scopes.stderr
rename to tests/ui/shadowed/shadowing-generic-item.stderr
index f0eaa1a5c64c4..55a0bb36ea80b 100644
--- a/tests/ui/lexical-scopes.stderr
+++ b/tests/ui/shadowed/shadowing-generic-item.stderr
@@ -1,5 +1,5 @@
 error[E0574]: expected struct, variant or union type, found type parameter `T`
-  --> $DIR/lexical-scopes.rs:3:13
+  --> $DIR/shadowing-generic-item.rs:5:13
    |
 LL | struct T { i: i32 }
    |        - you might have meant to refer to this struct
@@ -9,7 +9,7 @@ LL |     let t = T { i: 0 };
    |             ^ not a struct, variant or union type
 
 error[E0599]: no function or associated item named `f` found for type parameter `Foo` in the current scope
-  --> $DIR/lexical-scopes.rs:10:10
+  --> $DIR/shadowing-generic-item.rs:12:10
    |
 LL | fn g<Foo>() {
    |      --- function or associated item `f` not found for this type parameter
diff --git a/tests/ui/structs/default-field-values/const-trait-default-field-value.rs b/tests/ui/structs/default-field-values/const-trait-default-field-value.rs
new file mode 100644
index 0000000000000..60c22efabc4de
--- /dev/null
+++ b/tests/ui/structs/default-field-values/const-trait-default-field-value.rs
@@ -0,0 +1,37 @@
+//@ check-pass
+
+// Ensure that `default_field_values` and `const_default` interact properly.
+
+#![feature(const_default)]
+#![feature(const_trait_impl)]
+#![feature(default_field_values)]
+#![feature(derive_const)]
+
+#[derive(PartialEq, Eq, Debug)]
+#[derive_const(Default)]
+struct S {
+    r: Option<String> = <Option<_> as Default>::default(),
+    s: String = String::default(),
+    o: Option<String> = Option::<String>::default(),
+    p: std::marker::PhantomData<()> = std::marker::PhantomData::default(),
+    q: Option<String> = <Option<String> as Default>::default(),
+    t: Option<String> = Option::default(),
+    v: Option<String> = const { Option::default() },
+}
+
+const _: S = S { .. };
+const _: S = const { S { .. } };
+const _: S = S::default();
+const _: S = const { S::default() };
+
+fn main() {
+    let s = S { .. };
+    assert_eq!(s.r, None);
+    assert_eq!(&s.s, "");
+    assert_eq!(s.o, None);
+    assert_eq!(s.p, std::marker::PhantomData);
+    assert_eq!(s.q, None);
+    assert_eq!(s.t, None);
+    assert_eq!(s.v, None);
+    assert_eq!(s, S::default());
+}
diff --git a/tests/ui/struct-ctor-mangling.rs b/tests/ui/symbol-names/struct-constructor-mangling.rs
similarity index 54%
rename from tests/ui/struct-ctor-mangling.rs
rename to tests/ui/symbol-names/struct-constructor-mangling.rs
index f32cbb7aaae99..ec8791e215491 100644
--- a/tests/ui/struct-ctor-mangling.rs
+++ b/tests/ui/symbol-names/struct-constructor-mangling.rs
@@ -1,3 +1,5 @@
+//! Test that the symbol mangling of Foo-the-constructor-function versus Foo-the-type do not collide
+
 //@ run-pass
 
 fn size_of_val<T>(_: &T) -> usize {
@@ -6,8 +8,6 @@ fn size_of_val<T>(_: &T) -> usize {
 
 struct Foo(#[allow(dead_code)] i64);
 
-// Test that the (symbol) mangling of `Foo` (the `struct` type) and that of
-// `typeof Foo` (the function type of the `struct` constructor) don't collide.
 fn main() {
     size_of_val(&Foo(0));
     size_of_val(&Foo);
diff --git a/tests/ui/traits/const-traits/const-impl-trait.rs b/tests/ui/traits/const-traits/const-impl-trait.rs
index dc960422a4a41..da28d9a47c31e 100644
--- a/tests/ui/traits/const-traits/const-impl-trait.rs
+++ b/tests/ui/traits/const-traits/const-impl-trait.rs
@@ -1,7 +1,7 @@
 //@ compile-flags: -Znext-solver
 //@ known-bug: #110395
 
-// Broken until we have `const PartialEq` impl in stdlib
+// Broken until `(): const PartialEq`
 
 #![allow(incomplete_features)]
 #![feature(const_trait_impl, const_cmp, const_destruct)]
diff --git a/tests/ui/traits/const-traits/const_derives/derive-const-gate.stderr b/tests/ui/traits/const-traits/const_derives/derive-const-gate.stderr
index 5ed12b3705290..cbc62d602a473 100644
--- a/tests/ui/traits/const-traits/const_derives/derive-const-gate.stderr
+++ b/tests/ui/traits/const-traits/const_derives/derive-const-gate.stderr
@@ -4,6 +4,7 @@ error[E0658]: use of unstable library feature `derive_const`
 LL | #[derive_const(Debug)]
    |   ^^^^^^^^^^^^
    |
+   = note: see issue #118304 <https://github.com/rust-lang/rust/issues/118304> for more information
    = help: add `#![feature(derive_const)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
diff --git a/tests/ui/traits/const-traits/match-non-const-eq.gated.stderr b/tests/ui/traits/const-traits/match-non-const-eq.gated.stderr
deleted file mode 100644
index 89e59e5db6ed3..0000000000000
--- a/tests/ui/traits/const-traits/match-non-const-eq.gated.stderr
+++ /dev/null
@@ -1,12 +0,0 @@
-error[E0015]: cannot match on `str` in constant functions
-  --> $DIR/match-non-const-eq.rs:7:9
-   |
-LL |         "a" => (), //FIXME [gated]~ ERROR can't compare `str` with `str` in const contexts
-   |         ^^^
-   |
-   = note: `str` cannot be compared in compile-time, and therefore cannot be used in `match`es
-   = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants
-
-error: aborting due to 1 previous error
-
-For more information about this error, try `rustc --explain E0015`.
diff --git a/tests/ui/traits/const-traits/match-non-const-eq.rs b/tests/ui/traits/const-traits/match-non-const-eq.rs
index 73f8af86bd050..03adb8dc5a4e5 100644
--- a/tests/ui/traits/const-traits/match-non-const-eq.rs
+++ b/tests/ui/traits/const-traits/match-non-const-eq.rs
@@ -1,11 +1,12 @@
-//@ known-bug: #110395
 //@ revisions: stock gated
-#![cfg_attr(gated, feature(const_trait_impl))]
+#![cfg_attr(gated, feature(const_trait_impl, const_cmp))]
+//@[gated] check-pass
 
 const fn foo(input: &'static str) {
     match input {
-        "a" => (), //FIXME [gated]~ ERROR can't compare `str` with `str` in const contexts
-        //FIXME ~^ ERROR cannot match on `str` in constant functions
+        "a" => (),
+        //[stock]~^ ERROR cannot match on `str` in constant functions
+        //[stock]~| ERROR `PartialEq` is not yet stable as a const trait
         _ => (),
     }
 }
diff --git a/tests/ui/traits/const-traits/match-non-const-eq.stock.stderr b/tests/ui/traits/const-traits/match-non-const-eq.stock.stderr
index 89e59e5db6ed3..5b662447bde18 100644
--- a/tests/ui/traits/const-traits/match-non-const-eq.stock.stderr
+++ b/tests/ui/traits/const-traits/match-non-const-eq.stock.stderr
@@ -1,12 +1,26 @@
-error[E0015]: cannot match on `str` in constant functions
+error[E0658]: cannot match on `str` in constant functions
   --> $DIR/match-non-const-eq.rs:7:9
    |
-LL |         "a" => (), //FIXME [gated]~ ERROR can't compare `str` with `str` in const contexts
+LL |         "a" => (),
    |         ^^^
    |
    = note: `str` cannot be compared in compile-time, and therefore cannot be used in `match`es
    = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants
+   = note: see issue #143874 <https://github.com/rust-lang/rust/issues/143874> for more information
+   = help: add `#![feature(const_trait_impl)]` 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: aborting due to 1 previous error
+error: `PartialEq` is not yet stable as a const trait
+  --> $DIR/match-non-const-eq.rs:7:9
+   |
+LL |         "a" => (),
+   |         ^^^
+   |
+help: add `#![feature(const_cmp)]` to the crate attributes to enable
+   |
+LL + #![feature(const_cmp)]
+   |
+
+error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0015`.
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/underscore-lifetime/raw-underscore-lifetime.rs b/tests/ui/underscore-lifetime/raw-underscore-lifetime.rs
new file mode 100644
index 0000000000000..874b3d2c48dbb
--- /dev/null
+++ b/tests/ui/underscore-lifetime/raw-underscore-lifetime.rs
@@ -0,0 +1,9 @@
+// This test is to ensure that the raw underscore lifetime won't emit two duplicate errors.
+// See issue #143152
+
+//@ edition: 2021
+
+fn f<'r#_>(){}
+//~^ ERROR `_` cannot be a raw lifetime
+
+fn main() {}
diff --git a/tests/ui/underscore-lifetime/raw-underscore-lifetime.stderr b/tests/ui/underscore-lifetime/raw-underscore-lifetime.stderr
new file mode 100644
index 0000000000000..bdb357a47f4b7
--- /dev/null
+++ b/tests/ui/underscore-lifetime/raw-underscore-lifetime.stderr
@@ -0,0 +1,8 @@
+error: `_` cannot be a raw lifetime
+  --> $DIR/raw-underscore-lifetime.rs:6:6
+   |
+LL | fn f<'r#_>(){}
+   |      ^^^^
+
+error: aborting due to 1 previous error
+
diff --git a/triagebot.toml b/triagebot.toml
index 2f8114aeb3b6b..61d8a814c89ee 100644
--- a/triagebot.toml
+++ b/triagebot.toml
@@ -471,6 +471,7 @@ trigger_files = [
 
 [autolabel."T-infra"]
 trigger_files = [
+    ".github/workflows",
     "src/ci",
     "src/tools/bump-stage0",
     "src/tools/cargotest",
@@ -598,6 +599,12 @@ trigger_files = [
     "src/tools/clippy",
 ]
 
+[autolabel."A-CI"]
+trigger_files = [
+    ".github/workflows",
+    "src/ci",
+]
+
 # ------------------------------------------------------------------------------
 # Prioritization and team nominations
 # ------------------------------------------------------------------------------
@@ -1316,6 +1323,7 @@ infra-ci = [
     "@Kobzol",
     "@marcoieni",
     "@jdno",
+    "@jieyouxu",
 ]
 rustdoc = [
     "@GuillaumeGomez",