diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index 37ee9a5140a06..03ad75ca8b4a4 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -427,7 +427,7 @@ pub fn lower_to_hir(tcx: TyCtxt<'_>, (): ()) -> hir::Crate<'_> {
     tcx.ensure_with_value().early_lint_checks(());
     tcx.ensure_with_value().debugger_visualizers(LOCAL_CRATE);
     tcx.ensure_with_value().get_lang_items(());
-    let (mut resolver, krate) = tcx.resolver_for_lowering(()).steal();
+    let (mut resolver, krate) = tcx.resolver_for_lowering().steal();
 
     let ast_index = index_crate(&resolver.node_id_to_def_id, &krate);
     let mut owners = IndexVec::from_fn_n(
diff --git a/compiler/rustc_ast_passes/src/ast_validation.rs b/compiler/rustc_ast_passes/src/ast_validation.rs
index 5321ba8a7cbab..2bef4c9122456 100644
--- a/compiler/rustc_ast_passes/src/ast_validation.rs
+++ b/compiler/rustc_ast_passes/src/ast_validation.rs
@@ -929,35 +929,38 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                         only_trait: only_trait.then_some(()),
                     };
 
-                self.visibility_not_permitted(
-                    &item.vis,
-                    errors::VisibilityNotPermittedNote::IndividualImplItems,
-                );
-                if let &Unsafe::Yes(span) = unsafety {
-                    self.dcx().emit_err(errors::InherentImplCannotUnsafe {
-                        span: self_ty.span,
-                        annotation_span: span,
-                        annotation: "unsafe",
-                        self_ty: self_ty.span,
-                    });
-                }
-                if let &ImplPolarity::Negative(span) = polarity {
-                    self.dcx().emit_err(error(span, "negative", false));
-                }
-                if let &Defaultness::Default(def_span) = defaultness {
-                    self.dcx().emit_err(error(def_span, "`default`", true));
-                }
-                if let &Const::Yes(span) = constness {
-                    self.dcx().emit_err(error(span, "`const`", true));
-                }
+                self.with_in_trait_impl(None, |this| {
+                    this.visibility_not_permitted(
+                        &item.vis,
+                        errors::VisibilityNotPermittedNote::IndividualImplItems,
+                    );
+                    if let &Unsafe::Yes(span) = unsafety {
+                        this.dcx().emit_err(errors::InherentImplCannotUnsafe {
+                            span: self_ty.span,
+                            annotation_span: span,
+                            annotation: "unsafe",
+                            self_ty: self_ty.span,
+                        });
+                    }
+                    if let &ImplPolarity::Negative(span) = polarity {
+                        this.dcx().emit_err(error(span, "negative", false));
+                    }
+                    if let &Defaultness::Default(def_span) = defaultness {
+                        this.dcx().emit_err(error(def_span, "`default`", true));
+                    }
+                    if let &Const::Yes(span) = constness {
+                        this.dcx().emit_err(error(span, "`const`", true));
+                    }
 
-                self.visit_vis(&item.vis);
-                self.visit_ident(item.ident);
-                self.with_tilde_const(Some(DisallowTildeConstContext::Impl(item.span)), |this| {
-                    this.visit_generics(generics)
+                    this.visit_vis(&item.vis);
+                    this.visit_ident(item.ident);
+                    this.with_tilde_const(
+                        Some(DisallowTildeConstContext::Impl(item.span)),
+                        |this| this.visit_generics(generics),
+                    );
+                    this.visit_ty(self_ty);
+                    walk_list!(this, visit_assoc_item, items, AssocCtxt::Impl);
                 });
-                self.visit_ty(self_ty);
-                walk_list!(self, visit_assoc_item, items, AssocCtxt::Impl);
                 walk_list!(self, visit_attribute, &item.attrs);
                 return; // Avoid visiting again.
             }
diff --git a/compiler/rustc_ast_passes/src/feature_gate.rs b/compiler/rustc_ast_passes/src/feature_gate.rs
index d9e3f028697e0..2e14238f950f2 100644
--- a/compiler/rustc_ast_passes/src/feature_gate.rs
+++ b/compiler/rustc_ast_passes/src/feature_gate.rs
@@ -206,14 +206,6 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                 );
             }
         }
-        if !attr.is_doc_comment()
-            && let [seg, _] = attr.get_normal_item().path.segments.as_slice()
-            && seg.ident.name == sym::diagnostic
-            && !self.features.diagnostic_namespace
-        {
-            let msg = "`#[diagnostic]` attribute name space is experimental";
-            gate!(self, diagnostic_namespace, seg.ident.span, msg);
-        }
 
         // Emit errors for non-staged-api crates.
         if !self.features.staged_api {
diff --git a/compiler/rustc_driver_impl/src/lib.rs b/compiler/rustc_driver_impl/src/lib.rs
index 3b6bf0005a3b1..89ab5c6bd3b76 100644
--- a/compiler/rustc_driver_impl/src/lib.rs
+++ b/compiler/rustc_driver_impl/src/lib.rs
@@ -418,7 +418,7 @@ fn run_compiler(
             }
 
             // Make sure name resolution and macro expansion is run.
-            queries.global_ctxt()?.enter(|tcx| tcx.resolver_for_lowering(()));
+            queries.global_ctxt()?.enter(|tcx| tcx.resolver_for_lowering());
 
             if callbacks.after_expansion(compiler, queries) == Compilation::Stop {
                 return early_exit();
diff --git a/compiler/rustc_driver_impl/src/pretty.rs b/compiler/rustc_driver_impl/src/pretty.rs
index 768d98ce01efe..c9bbe45b21276 100644
--- a/compiler/rustc_driver_impl/src/pretty.rs
+++ b/compiler/rustc_driver_impl/src/pretty.rs
@@ -229,7 +229,7 @@ impl<'tcx> PrintExtra<'tcx> {
     {
         match self {
             PrintExtra::AfterParsing { krate, .. } => f(krate),
-            PrintExtra::NeedsAstMap { tcx } => f(&tcx.resolver_for_lowering(()).borrow().1),
+            PrintExtra::NeedsAstMap { tcx } => f(&tcx.resolver_for_lowering().borrow().1),
         }
     }
 
@@ -281,7 +281,7 @@ pub fn print<'tcx>(sess: &Session, ppm: PpMode, ex: PrintExtra<'tcx>) {
         }
         AstTreeExpanded => {
             debug!("pretty-printing expanded AST");
-            format!("{:#?}", ex.tcx().resolver_for_lowering(()).borrow().1)
+            format!("{:#?}", ex.tcx().resolver_for_lowering().borrow().1)
         }
         Hir(s) => {
             debug!("pretty printing HIR {:?}", s);
diff --git a/compiler/rustc_feature/src/accepted.rs b/compiler/rustc_feature/src/accepted.rs
index 1b2993dabdb83..7e5197f16f91e 100644
--- a/compiler/rustc_feature/src/accepted.rs
+++ b/compiler/rustc_feature/src/accepted.rs
@@ -146,6 +146,8 @@ declare_features! (
     (accepted, derive_default_enum, "1.62.0", Some(86985)),
     /// Allows the use of destructuring assignments.
     (accepted, destructuring_assignment, "1.59.0", Some(71126)),
+    /// Allows using the `#[diagnostic]` attribute tool namespace
+    (accepted, diagnostic_namespace, "CURRENT_RUSTC_VERSION", Some(111996)),
     /// Allows `#[doc(alias = "...")]`.
     (accepted, doc_alias, "1.48.0", Some(50146)),
     /// Allows `..` in tuple (struct) patterns.
diff --git a/compiler/rustc_feature/src/unstable.rs b/compiler/rustc_feature/src/unstable.rs
index 17c4d81474e27..9f4bead21dc6d 100644
--- a/compiler/rustc_feature/src/unstable.rs
+++ b/compiler/rustc_feature/src/unstable.rs
@@ -436,8 +436,6 @@ declare_features! (
     (unstable, deprecated_safe, "1.61.0", Some(94978)),
     /// Allows having using `suggestion` in the `#[deprecated]` attribute.
     (unstable, deprecated_suggestion, "1.61.0", Some(94785)),
-    /// Allows using the `#[diagnostic]` attribute tool namespace
-    (unstable, diagnostic_namespace, "1.73.0", Some(111996)),
     /// Controls errors in trait implementations.
     (unstable, do_not_recommend, "1.67.0", Some(51992)),
     /// Tells rustdoc to automatically generate `#[doc(cfg(...))]`.
diff --git a/compiler/rustc_infer/src/infer/higher_ranked/README.md b/compiler/rustc_infer/src/infer/higher_ranked/README.md
deleted file mode 100644
index 533d0ef7e6c4b..0000000000000
--- a/compiler/rustc_infer/src/infer/higher_ranked/README.md
+++ /dev/null
@@ -1,8 +0,0 @@
-To learn more about how Higher-ranked trait bounds work in the _old_ trait
-solver, see [this chapter][oldhrtb] of the rustc-dev-guide.
-
-To learn more about how they work in the _new_ trait solver, see [this
-chapter][newhrtb].
-
-[oldhrtb]: https://rustc-dev-guide.rust-lang.org/traits/hrtb.html
-[newhrtb]: https://rustc-dev-guide.rust-lang.org/borrow_check/region_inference.html#placeholders-and-universes
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index 73a25637e1ade..15cdd6a910e77 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -1,23 +1,25 @@
-pub use self::at::DefineOpaqueTypes;
-pub use self::freshen::TypeFreshener;
-pub use self::lexical_region_resolve::RegionResolutionError;
-pub use self::BoundRegionConversionTime::*;
-pub use self::RegionVariableOrigin::*;
-pub use self::SubregionOrigin::*;
-pub use self::ValuePairs::*;
+pub use at::DefineOpaqueTypes;
+pub use freshen::TypeFreshener;
+pub use lexical_region_resolve::RegionResolutionError;
+pub use relate::combine::CombineFields;
 pub use relate::combine::ObligationEmittingRelation;
-use rustc_data_structures::captures::Captures;
-use rustc_data_structures::undo_log::UndoLogs;
-use rustc_middle::infer::unify_key::EffectVarValue;
-use rustc_middle::infer::unify_key::{ConstVidKey, EffectVidKey};
-
-use self::opaque_types::OpaqueTypeStorage;
-pub(crate) use self::undo_log::{InferCtxtUndoLogs, Snapshot, UndoLog};
+pub use relate::StructurallyRelateAliases;
+pub use rustc_middle::ty::IntVarValue;
+pub use BoundRegionConversionTime::*;
+pub use RegionVariableOrigin::*;
+pub use SubregionOrigin::*;
+pub use ValuePairs::*;
 
 use crate::traits::{
     self, ObligationCause, ObligationInspector, PredicateObligations, TraitEngine, TraitEngineExt,
 };
-
+use error_reporting::TypeErrCtxt;
+use free_regions::RegionRelations;
+use lexical_region_resolve::LexicalRegionResolutions;
+use opaque_types::OpaqueTypeStorage;
+use region_constraints::{GenericKind, VarInfos, VerifyBound};
+use region_constraints::{RegionConstraintCollector, RegionConstraintStorage};
+use rustc_data_structures::captures::Captures;
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::sync::Lrc;
@@ -27,7 +29,9 @@ use rustc_errors::{Diag, DiagCtxt, ErrorGuaranteed};
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_middle::infer::canonical::{Canonical, CanonicalVarValues};
 use rustc_middle::infer::unify_key::ConstVariableValue;
+use rustc_middle::infer::unify_key::EffectVarValue;
 use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind, ToType};
+use rustc_middle::infer::unify_key::{ConstVidKey, EffectVidKey};
 use rustc_middle::mir::interpret::{ErrorHandled, EvalToValTreeResult};
 use rustc_middle::mir::ConstraintCategory;
 use rustc_middle::traits::{select, DefiningAnchor};
@@ -36,33 +40,21 @@ use rustc_middle::ty::fold::BoundVarReplacerDelegate;
 use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
 use rustc_middle::ty::relate::RelateResult;
 use rustc_middle::ty::visit::TypeVisitableExt;
-pub use rustc_middle::ty::IntVarValue;
 use rustc_middle::ty::{self, GenericParamDefKind, InferConst, InferTy, Ty, TyCtxt};
 use rustc_middle::ty::{ConstVid, EffectVid, FloatVid, IntVid, TyVid};
 use rustc_middle::ty::{GenericArg, GenericArgKind, GenericArgs, GenericArgsRef};
 use rustc_span::symbol::Symbol;
 use rustc_span::Span;
-
+use snapshot::undo_log::InferCtxtUndoLogs;
 use std::cell::{Cell, RefCell};
 use std::fmt;
-
-use self::error_reporting::TypeErrCtxt;
-use self::free_regions::RegionRelations;
-use self::lexical_region_resolve::LexicalRegionResolutions;
-use self::region_constraints::{GenericKind, VarInfos, VerifyBound};
-use self::region_constraints::{
-    RegionConstraintCollector, RegionConstraintStorage, RegionSnapshot,
-};
-pub use self::relate::combine::CombineFields;
-pub use self::relate::StructurallyRelateAliases;
-use self::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
+use type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 
 pub mod at;
 pub mod canonical;
 pub mod error_reporting;
 pub mod free_regions;
 mod freshen;
-mod fudge;
 mod lexical_region_resolve;
 pub mod opaque_types;
 pub mod outlives;
@@ -70,8 +62,8 @@ mod projection;
 pub mod region_constraints;
 mod relate;
 pub mod resolve;
+pub(crate) mod snapshot;
 pub mod type_variable;
-mod undo_log;
 
 #[must_use]
 #[derive(Debug)]
@@ -738,13 +730,6 @@ impl<'tcx> InferOk<'tcx, ()> {
     }
 }
 
-#[must_use = "once you start a snapshot, you should always consume it"]
-pub struct CombinedSnapshot<'tcx> {
-    undo_snapshot: Snapshot<'tcx>,
-    region_constraints_snapshot: RegionSnapshot,
-    universe: ty::UniverseIndex,
-}
-
 impl<'tcx> InferCtxt<'tcx> {
     pub fn dcx(&self) -> &'tcx DiagCtxt {
         self.tcx.dcx()
@@ -842,90 +827,6 @@ impl<'tcx> InferCtxt<'tcx> {
         }
     }
 
-    pub fn in_snapshot(&self) -> bool {
-        UndoLogs::<UndoLog<'tcx>>::in_snapshot(&self.inner.borrow_mut().undo_log)
-    }
-
-    pub fn num_open_snapshots(&self) -> usize {
-        UndoLogs::<UndoLog<'tcx>>::num_open_snapshots(&self.inner.borrow_mut().undo_log)
-    }
-
-    fn start_snapshot(&self) -> CombinedSnapshot<'tcx> {
-        debug!("start_snapshot()");
-
-        let mut inner = self.inner.borrow_mut();
-
-        CombinedSnapshot {
-            undo_snapshot: inner.undo_log.start_snapshot(),
-            region_constraints_snapshot: inner.unwrap_region_constraints().start_snapshot(),
-            universe: self.universe(),
-        }
-    }
-
-    #[instrument(skip(self, snapshot), level = "debug")]
-    fn rollback_to(&self, snapshot: CombinedSnapshot<'tcx>) {
-        let CombinedSnapshot { undo_snapshot, region_constraints_snapshot, universe } = snapshot;
-
-        self.universe.set(universe);
-
-        let mut inner = self.inner.borrow_mut();
-        inner.rollback_to(undo_snapshot);
-        inner.unwrap_region_constraints().rollback_to(region_constraints_snapshot);
-    }
-
-    #[instrument(skip(self, snapshot), level = "debug")]
-    fn commit_from(&self, snapshot: CombinedSnapshot<'tcx>) {
-        let CombinedSnapshot { undo_snapshot, region_constraints_snapshot: _, universe: _ } =
-            snapshot;
-
-        self.inner.borrow_mut().commit(undo_snapshot);
-    }
-
-    /// Execute `f` and commit the bindings if closure `f` returns `Ok(_)`.
-    #[instrument(skip(self, f), level = "debug")]
-    pub fn commit_if_ok<T, E, F>(&self, f: F) -> Result<T, E>
-    where
-        F: FnOnce(&CombinedSnapshot<'tcx>) -> Result<T, E>,
-    {
-        let snapshot = self.start_snapshot();
-        let r = f(&snapshot);
-        debug!("commit_if_ok() -- r.is_ok() = {}", r.is_ok());
-        match r {
-            Ok(_) => {
-                self.commit_from(snapshot);
-            }
-            Err(_) => {
-                self.rollback_to(snapshot);
-            }
-        }
-        r
-    }
-
-    /// Execute `f` then unroll any bindings it creates.
-    #[instrument(skip(self, f), level = "debug")]
-    pub fn probe<R, F>(&self, f: F) -> R
-    where
-        F: FnOnce(&CombinedSnapshot<'tcx>) -> R,
-    {
-        let snapshot = self.start_snapshot();
-        let r = f(&snapshot);
-        self.rollback_to(snapshot);
-        r
-    }
-
-    /// Scan the constraints produced since `snapshot` and check whether
-    /// we added any region constraints.
-    pub fn region_constraints_added_in_snapshot(&self, snapshot: &CombinedSnapshot<'tcx>) -> bool {
-        self.inner
-            .borrow_mut()
-            .unwrap_region_constraints()
-            .region_constraints_added_in_snapshot(&snapshot.undo_snapshot)
-    }
-
-    pub fn opaque_types_added_in_snapshot(&self, snapshot: &CombinedSnapshot<'tcx>) -> bool {
-        self.inner.borrow().undo_log.opaque_types_in_snapshot(&snapshot.undo_snapshot)
-    }
-
     pub fn can_sub<T>(&self, param_env: ty::ParamEnv<'tcx>, expected: T, actual: T) -> bool
     where
         T: at::ToTrace<'tcx>,
diff --git a/compiler/rustc_infer/src/infer/opaque_types.rs b/compiler/rustc_infer/src/infer/opaque_types/mod.rs
similarity index 100%
rename from compiler/rustc_infer/src/infer/opaque_types.rs
rename to compiler/rustc_infer/src/infer/opaque_types/mod.rs
diff --git a/compiler/rustc_infer/src/infer/opaque_types/table.rs b/compiler/rustc_infer/src/infer/opaque_types/table.rs
index 9f49ed00219c9..a7ddf47543628 100644
--- a/compiler/rustc_infer/src/infer/opaque_types/table.rs
+++ b/compiler/rustc_infer/src/infer/opaque_types/table.rs
@@ -1,7 +1,7 @@
 use rustc_data_structures::undo_log::UndoLogs;
 use rustc_middle::ty::{self, OpaqueHiddenType, OpaqueTypeKey, Ty};
 
-use crate::infer::{InferCtxtUndoLogs, UndoLog};
+use crate::infer::snapshot::undo_log::{InferCtxtUndoLogs, UndoLog};
 
 use super::{OpaqueTypeDecl, OpaqueTypeMap};
 
diff --git a/compiler/rustc_infer/src/infer/outlives/obligations.rs b/compiler/rustc_infer/src/infer/outlives/obligations.rs
index 8dd3a1f40cc10..fe323982ec03c 100644
--- a/compiler/rustc_infer/src/infer/outlives/obligations.rs
+++ b/compiler/rustc_infer/src/infer/outlives/obligations.rs
@@ -63,9 +63,8 @@ use crate::infer::outlives::components::{push_outlives_components, Component};
 use crate::infer::outlives::env::RegionBoundPairs;
 use crate::infer::outlives::verify::VerifyBoundCx;
 use crate::infer::resolve::OpportunisticRegionResolver;
-use crate::infer::{
-    self, GenericKind, InferCtxt, RegionObligation, SubregionOrigin, UndoLog, VerifyBound,
-};
+use crate::infer::snapshot::undo_log::UndoLog;
+use crate::infer::{self, GenericKind, InferCtxt, RegionObligation, SubregionOrigin, VerifyBound};
 use crate::traits::{ObligationCause, ObligationCauseCode};
 use rustc_data_structures::undo_log::UndoLogs;
 use rustc_middle::mir::ConstraintCategory;
diff --git a/compiler/rustc_infer/src/infer/region_constraints/leak_check.rs b/compiler/rustc_infer/src/infer/region_constraints/leak_check.rs
index 9e2f3a10b6a6e..06f8dd4a4c6cd 100644
--- a/compiler/rustc_infer/src/infer/region_constraints/leak_check.rs
+++ b/compiler/rustc_infer/src/infer/region_constraints/leak_check.rs
@@ -1,9 +1,7 @@
 use super::*;
-use crate::infer::CombinedSnapshot;
-use rustc_data_structures::{
-    fx::FxIndexMap,
-    graph::{scc::Sccs, vec_graph::VecGraph},
-};
+use crate::infer::snapshot::CombinedSnapshot;
+use rustc_data_structures::fx::FxIndexMap;
+use rustc_data_structures::graph::{scc::Sccs, vec_graph::VecGraph};
 use rustc_index::Idx;
 use rustc_middle::ty::error::TypeError;
 use rustc_middle::ty::relate::RelateResult;
diff --git a/compiler/rustc_infer/src/infer/region_constraints/mod.rs b/compiler/rustc_infer/src/infer/region_constraints/mod.rs
index ee97dd3680759..0f3f2bc5fa634 100644
--- a/compiler/rustc_infer/src/infer/region_constraints/mod.rs
+++ b/compiler/rustc_infer/src/infer/region_constraints/mod.rs
@@ -3,9 +3,8 @@
 use self::CombineMapType::*;
 use self::UndoLog::*;
 
-use super::{
-    InferCtxtUndoLogs, MiscVariable, RegionVariableOrigin, Rollback, Snapshot, SubregionOrigin,
-};
+use super::{MiscVariable, RegionVariableOrigin, Rollback, SubregionOrigin};
+use crate::infer::snapshot::undo_log::{InferCtxtUndoLogs, Snapshot};
 
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::Lrc;
@@ -360,7 +359,7 @@ impl<'tcx> RegionConstraintCollector<'_, 'tcx> {
     ///
     /// Not legal during a snapshot.
     pub fn into_infos_and_data(self) -> (VarInfos, RegionConstraintData<'tcx>) {
-        assert!(!UndoLogs::<super::UndoLog<'_>>::in_snapshot(&self.undo_log));
+        assert!(!UndoLogs::<UndoLog<'_>>::in_snapshot(&self.undo_log));
         (mem::take(&mut self.storage.var_infos), mem::take(&mut self.storage.data))
     }
 
@@ -377,7 +376,7 @@ impl<'tcx> RegionConstraintCollector<'_, 'tcx> {
     ///
     /// Not legal during a snapshot.
     pub fn take_and_reset_data(&mut self) -> RegionConstraintData<'tcx> {
-        assert!(!UndoLogs::<super::UndoLog<'_>>::in_snapshot(&self.undo_log));
+        assert!(!UndoLogs::<UndoLog<'_>>::in_snapshot(&self.undo_log));
 
         // If you add a new field to `RegionConstraintCollector`, you
         // should think carefully about whether it needs to be cleared
diff --git a/compiler/rustc_infer/src/infer/relate/higher_ranked.rs b/compiler/rustc_infer/src/infer/relate/higher_ranked.rs
index cc0f00254ffd8..70ed7cf9af1ac 100644
--- a/compiler/rustc_infer/src/infer/relate/higher_ranked.rs
+++ b/compiler/rustc_infer/src/infer/relate/higher_ranked.rs
@@ -1,7 +1,7 @@
 //! Helper routines for higher-ranked things. See the `doc` module at
 //! the end of the file for details.
 
-use crate::infer::CombinedSnapshot;
+use crate::infer::snapshot::CombinedSnapshot;
 use crate::infer::InferCtxt;
 use rustc_middle::ty::fold::FnMutDelegate;
 use rustc_middle::ty::relate::RelateResult;
diff --git a/compiler/rustc_infer/src/infer/fudge.rs b/compiler/rustc_infer/src/infer/snapshot/fudge.rs
similarity index 98%
rename from compiler/rustc_infer/src/infer/fudge.rs
rename to compiler/rustc_infer/src/infer/snapshot/fudge.rs
index 99033922bdf76..14de461cd17eb 100644
--- a/compiler/rustc_infer/src/infer/fudge.rs
+++ b/compiler/rustc_infer/src/infer/snapshot/fudge.rs
@@ -2,9 +2,9 @@ use rustc_middle::infer::unify_key::{ConstVariableOriginKind, ConstVariableValue
 use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
 use rustc_middle::ty::{self, ConstVid, FloatVid, IntVid, RegionVid, Ty, TyCtxt, TyVid};
 
-use super::type_variable::TypeVariableOrigin;
-use super::InferCtxt;
-use super::{ConstVariableOrigin, RegionVariableOrigin, UnificationTable};
+use crate::infer::type_variable::TypeVariableOrigin;
+use crate::infer::InferCtxt;
+use crate::infer::{ConstVariableOrigin, RegionVariableOrigin, UnificationTable};
 
 use rustc_data_structures::snapshot_vec as sv;
 use rustc_data_structures::unify as ut;
diff --git a/compiler/rustc_infer/src/infer/snapshot/mod.rs b/compiler/rustc_infer/src/infer/snapshot/mod.rs
new file mode 100644
index 0000000000000..9eef1471b1af2
--- /dev/null
+++ b/compiler/rustc_infer/src/infer/snapshot/mod.rs
@@ -0,0 +1,102 @@
+use super::region_constraints::RegionSnapshot;
+use super::InferCtxt;
+use rustc_data_structures::undo_log::UndoLogs;
+use rustc_middle::ty;
+
+mod fudge;
+pub(crate) mod undo_log;
+
+use undo_log::{Snapshot, UndoLog};
+
+#[must_use = "once you start a snapshot, you should always consume it"]
+pub struct CombinedSnapshot<'tcx> {
+    pub(super) undo_snapshot: Snapshot<'tcx>,
+    region_constraints_snapshot: RegionSnapshot,
+    universe: ty::UniverseIndex,
+}
+
+impl<'tcx> InferCtxt<'tcx> {
+    pub fn in_snapshot(&self) -> bool {
+        UndoLogs::<UndoLog<'tcx>>::in_snapshot(&self.inner.borrow_mut().undo_log)
+    }
+
+    pub fn num_open_snapshots(&self) -> usize {
+        UndoLogs::<UndoLog<'tcx>>::num_open_snapshots(&self.inner.borrow_mut().undo_log)
+    }
+
+    fn start_snapshot(&self) -> CombinedSnapshot<'tcx> {
+        debug!("start_snapshot()");
+
+        let mut inner = self.inner.borrow_mut();
+
+        CombinedSnapshot {
+            undo_snapshot: inner.undo_log.start_snapshot(),
+            region_constraints_snapshot: inner.unwrap_region_constraints().start_snapshot(),
+            universe: self.universe(),
+        }
+    }
+
+    #[instrument(skip(self, snapshot), level = "debug")]
+    fn rollback_to(&self, snapshot: CombinedSnapshot<'tcx>) {
+        let CombinedSnapshot { undo_snapshot, region_constraints_snapshot, universe } = snapshot;
+
+        self.universe.set(universe);
+
+        let mut inner = self.inner.borrow_mut();
+        inner.rollback_to(undo_snapshot);
+        inner.unwrap_region_constraints().rollback_to(region_constraints_snapshot);
+    }
+
+    #[instrument(skip(self, snapshot), level = "debug")]
+    fn commit_from(&self, snapshot: CombinedSnapshot<'tcx>) {
+        let CombinedSnapshot { undo_snapshot, region_constraints_snapshot: _, universe: _ } =
+            snapshot;
+
+        self.inner.borrow_mut().commit(undo_snapshot);
+    }
+
+    /// Execute `f` and commit the bindings if closure `f` returns `Ok(_)`.
+    #[instrument(skip(self, f), level = "debug")]
+    pub fn commit_if_ok<T, E, F>(&self, f: F) -> Result<T, E>
+    where
+        F: FnOnce(&CombinedSnapshot<'tcx>) -> Result<T, E>,
+    {
+        let snapshot = self.start_snapshot();
+        let r = f(&snapshot);
+        debug!("commit_if_ok() -- r.is_ok() = {}", r.is_ok());
+        match r {
+            Ok(_) => {
+                self.commit_from(snapshot);
+            }
+            Err(_) => {
+                self.rollback_to(snapshot);
+            }
+        }
+        r
+    }
+
+    /// Execute `f` then unroll any bindings it creates.
+    #[instrument(skip(self, f), level = "debug")]
+    pub fn probe<R, F>(&self, f: F) -> R
+    where
+        F: FnOnce(&CombinedSnapshot<'tcx>) -> R,
+    {
+        let snapshot = self.start_snapshot();
+        let r = f(&snapshot);
+        self.rollback_to(snapshot);
+        r
+    }
+
+    /// Scan the constraints produced since `snapshot` and check whether
+    /// we added any region constraints.
+    pub fn region_constraints_added_in_snapshot(&self, snapshot: &CombinedSnapshot<'tcx>) -> bool {
+        self.inner
+            .borrow_mut()
+            .unwrap_region_constraints()
+            .region_constraints_added_in_snapshot(&snapshot.undo_snapshot)
+    }
+
+    pub fn opaque_types_added_in_snapshot(&self, snapshot: &CombinedSnapshot<'tcx>) -> bool {
+        self.inner.borrow().undo_log.opaque_types_in_snapshot(&snapshot.undo_snapshot)
+    }
+}
diff --git a/compiler/rustc_infer/src/infer/undo_log.rs b/compiler/rustc_infer/src/infer/snapshot/undo_log.rs
similarity index 100%
rename from compiler/rustc_infer/src/infer/undo_log.rs
rename to compiler/rustc_infer/src/infer/snapshot/undo_log.rs
diff --git a/compiler/rustc_infer/src/traits/project.rs b/compiler/rustc_infer/src/traits/project.rs
index afba2e50a23c5..31ceb2343324d 100644
--- a/compiler/rustc_infer/src/traits/project.rs
+++ b/compiler/rustc_infer/src/traits/project.rs
@@ -2,7 +2,7 @@
 
 use super::PredicateObligation;
 
-use crate::infer::InferCtxtUndoLogs;
+use crate::infer::snapshot::undo_log::InferCtxtUndoLogs;
 
 use rustc_data_structures::{
     snapshot_map::{self, SnapshotMapRef, SnapshotMapStorage},
diff --git a/compiler/rustc_interface/src/passes.rs b/compiler/rustc_interface/src/passes.rs
index 61f0ab14e8c1c..4b4c1d6cf672b 100644
--- a/compiler/rustc_interface/src/passes.rs
+++ b/compiler/rustc_interface/src/passes.rs
@@ -280,7 +280,7 @@ fn configure_and_expand(
 
 fn early_lint_checks(tcx: TyCtxt<'_>, (): ()) {
     let sess = tcx.sess;
-    let (resolver, krate) = &*tcx.resolver_for_lowering(()).borrow();
+    let (resolver, krate) = &*tcx.resolver_for_lowering().borrow();
     let mut lint_buffer = resolver.lint_buffer.steal();
 
     if sess.opts.unstable_opts.input_stats {
@@ -531,10 +531,10 @@ fn write_out_deps(tcx: TyCtxt<'_>, outputs: &OutputFilenames, out_filenames: &[P
     }
 }
 
-fn resolver_for_lowering<'tcx>(
+fn resolver_for_lowering_raw<'tcx>(
     tcx: TyCtxt<'tcx>,
     (): (),
-) -> &'tcx Steal<(ty::ResolverAstLowering, Lrc<ast::Crate>)> {
+) -> (&'tcx Steal<(ty::ResolverAstLowering, Lrc<ast::Crate>)>, &'tcx ty::ResolverGlobalCtxt) {
     let arenas = Resolver::arenas();
     let _ = tcx.registered_tools(()); // Uses `crate_for_resolver`.
     let (krate, pre_configured_attrs) = tcx.crate_for_resolver(()).steal();
@@ -549,16 +549,15 @@ fn resolver_for_lowering<'tcx>(
         ast_lowering: untracked_resolver_for_lowering,
     } = resolver.into_outputs();
 
-    let feed = tcx.feed_unit_query();
-    feed.resolutions(tcx.arena.alloc(untracked_resolutions));
-    tcx.arena.alloc(Steal::new((untracked_resolver_for_lowering, Lrc::new(krate))))
+    let resolutions = tcx.arena.alloc(untracked_resolutions);
+    (tcx.arena.alloc(Steal::new((untracked_resolver_for_lowering, Lrc::new(krate)))), resolutions)
 }
 
 pub(crate) fn write_dep_info(tcx: TyCtxt<'_>) {
     // Make sure name resolution and macro expansion is run for
     // the side-effect of providing a complete set of all
     // accessed files and env vars.
-    let _ = tcx.resolver_for_lowering(());
+    let _ = tcx.resolver_for_lowering();
 
     let sess = tcx.sess;
     let _timer = sess.timer("write_dep_info");
@@ -607,7 +606,10 @@ pub static DEFAULT_QUERY_PROVIDERS: LazyLock<Providers> = LazyLock::new(|| {
     let providers = &mut Providers::default();
     providers.analysis = analysis;
     providers.hir_crate = rustc_ast_lowering::lower_to_hir;
-    providers.resolver_for_lowering = resolver_for_lowering;
+    providers.resolver_for_lowering_raw = resolver_for_lowering_raw;
+    providers.stripped_cfg_items =
+        |tcx, _| tcx.arena.alloc_from_iter(tcx.resolutions(()).stripped_cfg_items.steal());
+    providers.resolutions = |tcx, ()| tcx.resolver_for_lowering_raw(()).1;
     providers.early_lint_checks = early_lint_checks;
     proc_macro_decls::provide(providers);
     rustc_const_eval::provide(providers);
diff --git a/compiler/rustc_interface/src/queries.rs b/compiler/rustc_interface/src/queries.rs
index 7cdf7cd25b1c1..da11d090b7497 100644
--- a/compiler/rustc_interface/src/queries.rs
+++ b/compiler/rustc_interface/src/queries.rs
@@ -8,8 +8,7 @@ use rustc_codegen_ssa::CodegenResults;
 use rustc_data_structures::steal::Steal;
 use rustc_data_structures::svh::Svh;
 use rustc_data_structures::sync::{AppendOnlyIndexVec, FreezeLock, OnceLock, WorkerLocal};
-use rustc_hir::def::DefKind;
-use rustc_hir::def_id::{StableCrateId, CRATE_DEF_ID, LOCAL_CRATE};
+use rustc_hir::def_id::{StableCrateId, LOCAL_CRATE};
 use rustc_hir::definitions::Definitions;
 use rustc_incremental::setup_dep_graph;
 use rustc_metadata::creader::CStore;
@@ -144,10 +143,8 @@ impl<'tcx> Queries<'tcx> {
                 stable_crate_id,
             )) as _);
             let definitions = FreezeLock::new(Definitions::new(stable_crate_id));
-            let source_span = AppendOnlyIndexVec::new();
-            let _id = source_span.push(krate.spans.inner_span);
-            debug_assert_eq!(_id, CRATE_DEF_ID);
-            let untracked = Untracked { cstore, source_span, definitions };
+            let untracked =
+                Untracked { cstore, source_span: AppendOnlyIndexVec::new(), definitions };
 
             let qcx = passes::create_global_ctxt(
                 self.compiler,
@@ -172,9 +169,6 @@ impl<'tcx> Queries<'tcx> {
                 )));
                 feed.crate_for_resolver(tcx.arena.alloc(Steal::new((krate, pre_configured_attrs))));
                 feed.output_filenames(Arc::new(outputs));
-
-                let feed = tcx.feed_local_def_id(CRATE_DEF_ID);
-                feed.def_kind(DefKind::Mod);
             });
             Ok(qcx)
         })
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 0268c530c9ee2..7c6e9762f2ae5 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -125,12 +125,11 @@ rustc_queries! {
     }
 
     query resolutions(_: ()) -> &'tcx ty::ResolverGlobalCtxt {
-        feedable
         no_hash
         desc { "getting the resolver outputs" }
     }
 
-    query resolver_for_lowering(_: ()) -> &'tcx Steal<(ty::ResolverAstLowering, Lrc<ast::Crate>)> {
+    query resolver_for_lowering_raw(_: ()) -> (&'tcx Steal<(ty::ResolverAstLowering, Lrc<ast::Crate>)>, &'tcx ty::ResolverGlobalCtxt) {
         eval_always
         no_hash
         desc { "getting the resolver for lowering" }
@@ -2216,7 +2215,6 @@ rustc_queries! {
     /// Should not be called for the local crate before the resolver outputs are created, as it
     /// is only fed there.
     query stripped_cfg_items(cnum: CrateNum) -> &'tcx [StrippedCfgItem] {
-        feedable
         desc { "getting cfg-ed out item names" }
         separate_provide_extern
     }
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index da81b9dd37558..4f8e4aa90f403 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -39,7 +39,7 @@ use rustc_data_structures::profiling::SelfProfilerRef;
 use rustc_data_structures::sharded::{IntoPointer, ShardedHashMap};
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::steal::Steal;
-use rustc_data_structures::sync::{self, FreezeReadGuard, Lock, WorkerLocal};
+use rustc_data_structures::sync::{self, FreezeReadGuard, Lock, Lrc, WorkerLocal};
 #[cfg(parallel_compiler)]
 use rustc_data_structures::sync::{DynSend, DynSync};
 use rustc_data_structures::unord::UnordSet;
@@ -60,7 +60,7 @@ use rustc_session::config::CrateType;
 use rustc_session::cstore::{CrateStoreDyn, Untracked};
 use rustc_session::lint::Lint;
 use rustc_session::{Limit, MetadataKind, Session};
-use rustc_span::def_id::{DefPathHash, StableCrateId};
+use rustc_span::def_id::{DefPathHash, StableCrateId, CRATE_DEF_ID};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{Span, DUMMY_SP};
 use rustc_target::abi::{FieldIdx, Layout, LayoutS, TargetDataLayout, VariantIdx};
@@ -74,6 +74,7 @@ use std::cmp::Ordering;
 use std::fmt;
 use std::hash::{Hash, Hasher};
 use std::iter;
+use std::marker::PhantomData;
 use std::mem;
 use std::ops::{Bound, Deref};
 
@@ -498,14 +499,55 @@ pub struct TyCtxtFeed<'tcx, KEY: Copy> {
     key: KEY,
 }
 
+/// Never return a `Feed` from a query. Only queries that create a `DefId` are
+/// allowed to feed queries for that `DefId`.
+impl<KEY: Copy, CTX> !HashStable<CTX> for TyCtxtFeed<'_, KEY> {}
+
+/// The same as `TyCtxtFeed`, but does not contain a `TyCtxt`.
+/// Use this to pass around when you have a `TyCtxt` elsewhere.
+/// Just an optimization to save space and not store hundreds of
+/// `TyCtxtFeed` in the resolver.
+#[derive(Copy, Clone)]
+pub struct Feed<'tcx, KEY: Copy> {
+    _tcx: PhantomData<TyCtxt<'tcx>>,
+    // Do not allow direct access, as downstream code must not mutate this field.
+    key: KEY,
+}
+
+/// Never return a `Feed` from a query. Only queries that create a `DefId` are
+/// allowed to feed queries for that `DefId`.
+impl<KEY: Copy, CTX> !HashStable<CTX> for Feed<'_, KEY> {}
+
+impl<T: fmt::Debug + Copy> fmt::Debug for Feed<'_, T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.key.fmt(f)
+    }
+}
+
+/// Some workarounds to use cases that cannot use `create_def`.
+/// Do not add new ways to create `TyCtxtFeed` without consulting
+/// with T-compiler and making an analysis about why your addition
+/// does not cause incremental compilation issues.
 impl<'tcx> TyCtxt<'tcx> {
+    /// Can only be fed before queries are run, and is thus exempt from any
+    /// incremental issues. Do not use except for the initial query feeding.
     pub fn feed_unit_query(self) -> TyCtxtFeed<'tcx, ()> {
+        self.dep_graph.assert_ignored();
         TyCtxtFeed { tcx: self, key: () }
     }
+
+    /// Can only be fed before queries are run, and is thus exempt from any
+    /// incremental issues. Do not use except for the initial query feeding.
     pub fn feed_local_crate(self) -> TyCtxtFeed<'tcx, CrateNum> {
+        self.dep_graph.assert_ignored();
         TyCtxtFeed { tcx: self, key: LOCAL_CRATE }
     }
-    pub fn feed_local_def_id(self, key: LocalDefId) -> TyCtxtFeed<'tcx, LocalDefId> {
+
+    /// Only used in the resolver to register the `CRATE_DEF_ID` `DefId` and feed
+    /// some queries for it. It will panic if used twice.
+    pub fn create_local_crate_def_id(self, span: Span) -> TyCtxtFeed<'tcx, LocalDefId> {
+        let key = self.untracked().source_span.push(span);
+        assert_eq!(key, CRATE_DEF_ID);
         TyCtxtFeed { tcx: self, key }
     }
 
@@ -523,6 +565,23 @@ impl<'tcx, KEY: Copy> TyCtxtFeed<'tcx, KEY> {
     pub fn key(&self) -> KEY {
         self.key
     }
+
+    #[inline(always)]
+    pub fn downgrade(self) -> Feed<'tcx, KEY> {
+        Feed { _tcx: PhantomData, key: self.key }
+    }
+}
+
+impl<'tcx, KEY: Copy> Feed<'tcx, KEY> {
+    #[inline(always)]
+    pub fn key(&self) -> KEY {
+        self.key
+    }
+
+    #[inline(always)]
+    pub fn upgrade(self, tcx: TyCtxt<'tcx>) -> TyCtxtFeed<'tcx, KEY> {
+        TyCtxtFeed { tcx, key: self.key }
+    }
 }
 
 impl<'tcx> TyCtxtFeed<'tcx, LocalDefId> {
@@ -1067,7 +1126,7 @@ impl<'tcx> TyCtxt<'tcx> {
         // needs to be re-evaluated.
         self.dep_graph.read_index(DepNodeIndex::FOREVER_RED_NODE);
 
-        let feed = self.feed_local_def_id(def_id);
+        let feed = TyCtxtFeed { tcx: self, key: def_id };
         feed.def_kind(def_kind);
         // Unique types created for closures participate in type privacy checking.
         // They have visibilities inherited from the module they are defined in.
@@ -2304,6 +2363,10 @@ impl<'tcx> TyCtxt<'tcx> {
         self.resolutions(()).module_children.get(&def_id).map_or(&[], |v| &v[..])
     }
 
+    pub fn resolver_for_lowering(self) -> &'tcx Steal<(ty::ResolverAstLowering, Lrc<ast::Crate>)> {
+        self.resolver_for_lowering_raw(()).0
+    }
+
     /// Given an `impl_id`, return the trait it implements.
     /// Return `None` if this is an inherent impl.
     pub fn impl_trait_ref(
diff --git a/compiler/rustc_middle/src/ty/instance.rs b/compiler/rustc_middle/src/ty/instance.rs
index 260d0885089ef..9fc8d418f5b25 100644
--- a/compiler/rustc_middle/src/ty/instance.rs
+++ b/compiler/rustc_middle/src/ty/instance.rs
@@ -694,6 +694,7 @@ impl<'tcx> Instance<'tcx> {
     }
 
     #[inline(always)]
+    // Keep me in sync with try_instantiate_mir_and_normalize_erasing_regions
     pub fn instantiate_mir_and_normalize_erasing_regions<T>(
         &self,
         tcx: TyCtxt<'tcx>,
@@ -701,16 +702,17 @@ impl<'tcx> Instance<'tcx> {
         v: EarlyBinder<T>,
     ) -> T
     where
-        T: TypeFoldable<TyCtxt<'tcx>> + Clone,
+        T: TypeFoldable<TyCtxt<'tcx>>,
     {
         if let Some(args) = self.args_for_mir_body() {
             tcx.instantiate_and_normalize_erasing_regions(args, param_env, v)
         } else {
-            tcx.normalize_erasing_regions(param_env, v.skip_binder())
+            tcx.normalize_erasing_regions(param_env, v.instantiate_identity())
         }
     }
 
     #[inline(always)]
+    // Keep me in sync with instantiate_mir_and_normalize_erasing_regions
     pub fn try_instantiate_mir_and_normalize_erasing_regions<T>(
         &self,
         tcx: TyCtxt<'tcx>,
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index d9f7ece83e0c9..4edec0e6951cd 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -32,6 +32,7 @@ pub use generic_args::*;
 pub use generics::*;
 pub use intrinsic::IntrinsicDef;
 use rustc_ast as ast;
+use rustc_ast::expand::StrippedCfgItem;
 use rustc_ast::node_id::NodeMap;
 pub use rustc_ast_ir::{try_visit, Movability, Mutability};
 use rustc_attr as attr;
@@ -85,7 +86,8 @@ pub use self::consts::{
     Const, ConstData, ConstInt, ConstKind, Expr, ScalarInt, UnevaluatedConst, ValTree,
 };
 pub use self::context::{
-    tls, CtxtInterners, DeducedParamAttrs, FreeRegionInfo, GlobalCtxt, Lift, TyCtxt, TyCtxtFeed,
+    tls, CtxtInterners, DeducedParamAttrs, Feed, FreeRegionInfo, GlobalCtxt, Lift, TyCtxt,
+    TyCtxtFeed,
 };
 pub use self::instance::{Instance, InstanceDef, ShortInstance, UnusedGenericParams};
 pub use self::list::List;
@@ -189,6 +191,7 @@ pub struct ResolverGlobalCtxt {
     pub doc_link_resolutions: FxHashMap<LocalDefId, DocLinkResMap>,
     pub doc_link_traits_in_scope: FxHashMap<LocalDefId, Vec<DefId>>,
     pub all_macro_rules: FxHashMap<Symbol, Res<ast::NodeId>>,
+    pub stripped_cfg_items: Steal<Vec<StrippedCfgItem>>,
 }
 
 /// Resolutions that should only be used for lowering.
diff --git a/compiler/rustc_mir_build/src/build/expr/into.rs b/compiler/rustc_mir_build/src/build/expr/into.rs
index 69f3d3101fa21..8a9dc34bc7bad 100644
--- a/compiler/rustc_mir_build/src/build/expr/into.rs
+++ b/compiler/rustc_mir_build/src/build/expr/into.rs
@@ -83,7 +83,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                                     block,
                                     cond,
                                     Some(condition_scope), // Temp scope
-                                    condition_scope,
                                     source_info,
                                     true, // Declare `let` bindings normally
                                 ));
@@ -156,7 +155,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                             block,
                             lhs,
                             Some(condition_scope), // Temp scope
-                            condition_scope,
                             source_info,
                             // This flag controls how inner `let` expressions are lowered,
                             // but either way there shouldn't be any of those in here.
diff --git a/compiler/rustc_mir_build/src/build/matches/mod.rs b/compiler/rustc_mir_build/src/build/matches/mod.rs
index 29ee07f5d79b7..31591983101f3 100644
--- a/compiler/rustc_mir_build/src/build/matches/mod.rs
+++ b/compiler/rustc_mir_build/src/build/matches/mod.rs
@@ -37,9 +37,6 @@ struct ThenElseArgs {
     /// Used as the temp scope for lowering `expr`. If absent (for match guards),
     /// `self.local_scope()` is used.
     temp_scope_override: Option<region::Scope>,
-    /// Scope to pass to [`Builder::break_for_else`]. Must match the scope used
-    /// by the enclosing call to [`Builder::in_if_then_scope`].
-    break_scope: region::Scope,
     variable_source_info: SourceInfo,
     /// Forwarded to [`Builder::lower_let_expr`] when lowering [`ExprKind::Let`].
     /// When false (for match guards), `let` bindings won't be declared.
@@ -58,19 +55,13 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         block: BasicBlock,
         expr_id: ExprId,
         temp_scope_override: Option<region::Scope>,
-        break_scope: region::Scope,
         variable_source_info: SourceInfo,
         declare_let_bindings: bool,
     ) -> BlockAnd<()> {
         self.then_else_break_inner(
             block,
             expr_id,
-            ThenElseArgs {
-                temp_scope_override,
-                break_scope,
-                variable_source_info,
-                declare_let_bindings,
-            },
+            ThenElseArgs { temp_scope_override, variable_source_info, declare_let_bindings },
         )
     }
 
@@ -97,11 +88,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         this.then_else_break_inner(
                             block,
                             lhs,
-                            ThenElseArgs {
-                                break_scope: local_scope,
-                                declare_let_bindings: true,
-                                ..args
-                            },
+                            ThenElseArgs { declare_let_bindings: true, ..args },
                         )
                     });
                 let rhs_success_block = unpack!(this.then_else_break_inner(
@@ -130,14 +117,10 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         this.then_else_break_inner(
                             block,
                             arg,
-                            ThenElseArgs {
-                                break_scope: local_scope,
-                                declare_let_bindings: true,
-                                ..args
-                            },
+                            ThenElseArgs { declare_let_bindings: true, ..args },
                         )
                     });
-                this.break_for_else(success_block, args.break_scope, args.variable_source_info);
+                this.break_for_else(success_block, args.variable_source_info);
                 failure_block.unit()
             }
             ExprKind::Scope { region_scope, lint_level, value } => {
@@ -151,7 +134,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 block,
                 expr,
                 pat,
-                args.break_scope,
                 Some(args.variable_source_info.scope),
                 args.variable_source_info.span,
                 args.declare_let_bindings,
@@ -170,7 +152,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
 
                 let source_info = this.source_info(expr_span);
                 this.cfg.terminate(block, source_info, term);
-                this.break_for_else(else_block, args.break_scope, source_info);
+                this.break_for_else(else_block, source_info);
 
                 then_block.unit()
             }
@@ -1911,7 +1893,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         mut block: BasicBlock,
         expr_id: ExprId,
         pat: &Pat<'tcx>,
-        else_target: region::Scope,
         source_scope: Option<SourceScope>,
         span: Span,
         declare_bindings: bool,
@@ -1933,7 +1914,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         let expr_place = expr_place_builder.try_to_place(self);
         let opt_expr_place = expr_place.as_ref().map(|place| (Some(place), expr_span));
         let otherwise_post_guard_block = otherwise_candidate.pre_binding_block.unwrap();
-        self.break_for_else(otherwise_post_guard_block, else_target, self.source_info(expr_span));
+        self.break_for_else(otherwise_post_guard_block, self.source_info(expr_span));
 
         if declare_bindings {
             self.declare_bindings(source_scope, pat.span.to(span), pat, None, opt_expr_place);
@@ -2110,7 +2091,6 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         block,
                         guard,
                         None, // Use `self.local_scope()` as the temp scope
-                        match_scope,
                         this.source_info(arm.span),
                         false, // For guards, `let` bindings are declared separately
                     )
@@ -2443,7 +2423,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 None,
                 true,
             );
-            this.break_for_else(failure, *let_else_scope, this.source_info(initializer_span));
+            this.break_for_else(failure, this.source_info(initializer_span));
             matching.unit()
         });
         matching.and(failure)
diff --git a/compiler/rustc_mir_build/src/build/scope.rs b/compiler/rustc_mir_build/src/build/scope.rs
index 04740a9629152..961502566baaa 100644
--- a/compiler/rustc_mir_build/src/build/scope.rs
+++ b/compiler/rustc_mir_build/src/build/scope.rs
@@ -683,20 +683,23 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         self.cfg.start_new_block().unit()
     }
 
-    pub(crate) fn break_for_else(
-        &mut self,
-        block: BasicBlock,
-        target: region::Scope,
-        source_info: SourceInfo,
-    ) {
-        let scope_index = self.scopes.scope_index(target, source_info.span);
+    /// Sets up the drops for breaking from `block` due to an `if` condition
+    /// that turned out to be false.
+    ///
+    /// Must be called in the context of [`Builder::in_if_then_scope`], so that
+    /// there is an if-then scope to tell us what the target scope is.
+    pub(crate) fn break_for_else(&mut self, block: BasicBlock, source_info: SourceInfo) {
         let if_then_scope = self
             .scopes
             .if_then_scope
-            .as_mut()
+            .as_ref()
             .unwrap_or_else(|| span_bug!(source_info.span, "no if-then scope found"));
 
-        assert_eq!(if_then_scope.region_scope, target, "breaking to incorrect scope");
+        let target = if_then_scope.region_scope;
+        let scope_index = self.scopes.scope_index(target, source_info.span);
+
+        // Upgrade `if_then_scope` to `&mut`.
+        let if_then_scope = self.scopes.if_then_scope.as_mut().expect("upgrading & to &mut");
 
         let mut drop_idx = ROOT_NODE;
         let drops = &mut if_then_scope.else_drops;
diff --git a/compiler/rustc_passes/src/debugger_visualizer.rs b/compiler/rustc_passes/src/debugger_visualizer.rs
index 4bfe6be549377..96893e585491f 100644
--- a/compiler/rustc_passes/src/debugger_visualizer.rs
+++ b/compiler/rustc_passes/src/debugger_visualizer.rs
@@ -87,7 +87,7 @@ impl<'ast> rustc_ast::visit::Visitor<'ast> for DebuggerVisualizerCollector<'_> {
 
 /// Traverses and collects the debugger visualizers for a specific crate.
 fn debugger_visualizers(tcx: TyCtxt<'_>, _: LocalCrate) -> Vec<DebuggerVisualizerFile> {
-    let resolver_and_krate = tcx.resolver_for_lowering(()).borrow();
+    let resolver_and_krate = tcx.resolver_for_lowering().borrow();
     let krate = &*resolver_and_krate.1;
 
     let mut visitor = DebuggerVisualizerCollector { sess: tcx.sess, visualizers: Vec::new() };
diff --git a/compiler/rustc_passes/src/lang_items.rs b/compiler/rustc_passes/src/lang_items.rs
index d3e3e183845ee..d1368267224a7 100644
--- a/compiler/rustc_passes/src/lang_items.rs
+++ b/compiler/rustc_passes/src/lang_items.rs
@@ -243,7 +243,7 @@ impl<'ast, 'tcx> LanguageItemCollector<'ast, 'tcx> {
 
 /// Traverses and collects all the lang items in all crates.
 fn get_lang_items(tcx: TyCtxt<'_>, (): ()) -> LanguageItems {
-    let resolver = tcx.resolver_for_lowering(()).borrow();
+    let resolver = tcx.resolver_for_lowering().borrow();
     let (resolver, krate) = &*resolver;
 
     // Initialize the collector.
diff --git a/compiler/rustc_resolve/src/build_reduced_graph.rs b/compiler/rustc_resolve/src/build_reduced_graph.rs
index 1c4aeefcbcfd0..dd18ab7d9d23e 100644
--- a/compiler/rustc_resolve/src/build_reduced_graph.rs
+++ b/compiler/rustc_resolve/src/build_reduced_graph.rs
@@ -25,6 +25,7 @@ use rustc_hir::def::{self, *};
 use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID};
 use rustc_metadata::creader::LoadedMacro;
 use rustc_middle::metadata::ModChild;
+use rustc_middle::ty::Feed;
 use rustc_middle::{bug, ty};
 use rustc_span::hygiene::{ExpnId, LocalExpnId, MacroKind};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
@@ -407,7 +408,7 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
         // Top level use tree reuses the item's id and list stems reuse their parent
         // use tree's ids, so in both cases their visibilities are already filled.
         if nested && !list_stem {
-            self.r.feed_visibility(self.r.local_def_id(id), vis);
+            self.r.feed_visibility(self.r.feed(id), vis);
         }
 
         let mut prefix_iter = parent_prefix
@@ -632,7 +633,7 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
         &mut self,
         fields: &[ast::FieldDef],
         ident: Ident,
-        def_id: LocalDefId,
+        feed: Feed<'tcx, LocalDefId>,
         adt_res: Res,
         adt_vis: ty::Visibility,
         adt_span: Span,
@@ -643,7 +644,8 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
 
         // Define a name in the type namespace if it is not anonymous.
         self.r.define(parent, ident, TypeNS, (adt_res, adt_vis, adt_span, expansion));
-        self.r.feed_visibility(def_id, adt_vis);
+        self.r.feed_visibility(feed, adt_vis);
+        let def_id = feed.key();
 
         // Record field names for error reporting.
         self.insert_field_def_ids(def_id, fields);
@@ -653,14 +655,15 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
             match &field.ty.kind {
                 ast::TyKind::AnonStruct(id, nested_fields)
                 | ast::TyKind::AnonUnion(id, nested_fields) => {
-                    let local_def_id = self.r.local_def_id(*id);
+                    let feed = self.r.feed(*id);
+                    let local_def_id = feed.key();
                     let def_id = local_def_id.to_def_id();
                     let def_kind = self.r.tcx.def_kind(local_def_id);
                     let res = Res::Def(def_kind, def_id);
                     self.build_reduced_graph_for_struct_variant(
                         &nested_fields,
                         Ident::empty(),
-                        local_def_id,
+                        feed,
                         res,
                         // Anonymous adts inherit visibility from their parent adts.
                         adt_vis,
@@ -680,12 +683,13 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
         let ident = item.ident;
         let sp = item.span;
         let vis = self.resolve_visibility(&item.vis);
-        let local_def_id = self.r.local_def_id(item.id);
+        let feed = self.r.feed(item.id);
+        let local_def_id = feed.key();
         let def_id = local_def_id.to_def_id();
         let def_kind = self.r.tcx.def_kind(def_id);
         let res = Res::Def(def_kind, def_id);
 
-        self.r.feed_visibility(local_def_id, vis);
+        self.r.feed_visibility(feed, vis);
 
         match item.kind {
             ItemKind::Use(ref use_tree) => {
@@ -762,7 +766,7 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
                 self.build_reduced_graph_for_struct_variant(
                     vdata.fields(),
                     ident,
-                    local_def_id,
+                    feed,
                     res,
                     vis,
                     sp,
@@ -795,10 +799,11 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
                         }
                         ret_fields.push(field_vis.to_def_id());
                     }
-                    let ctor_def_id = self.r.local_def_id(ctor_node_id);
+                    let feed = self.r.feed(ctor_node_id);
+                    let ctor_def_id = feed.key();
                     let ctor_res = self.res(ctor_def_id);
                     self.r.define(parent, ident, ValueNS, (ctor_res, ctor_vis, sp, expansion));
-                    self.r.feed_visibility(ctor_def_id, ctor_vis);
+                    self.r.feed_visibility(feed, ctor_vis);
                     // We need the field visibility spans also for the constructor for E0603.
                     self.insert_field_visibilities_local(ctor_def_id.to_def_id(), vdata.fields());
 
@@ -812,7 +817,7 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
                 self.build_reduced_graph_for_struct_variant(
                     vdata.fields(),
                     ident,
-                    local_def_id,
+                    feed,
                     res,
                     vis,
                     sp,
@@ -919,7 +924,8 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
 
     /// Constructs the reduced graph for one foreign item.
     fn build_reduced_graph_for_foreign_item(&mut self, item: &ForeignItem) {
-        let local_def_id = self.r.local_def_id(item.id);
+        let feed = self.r.feed(item.id);
+        let local_def_id = feed.key();
         let def_id = local_def_id.to_def_id();
         let ns = match item.kind {
             ForeignItemKind::Fn(..) => ValueNS,
@@ -931,7 +937,7 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
         let expansion = self.parent_scope.expansion;
         let vis = self.resolve_visibility(&item.vis);
         self.r.define(parent, item.ident, ns, (self.res(def_id), vis, item.span, expansion));
-        self.r.feed_visibility(local_def_id, vis);
+        self.r.feed_visibility(feed, vis);
     }
 
     fn build_reduced_graph_for_block(&mut self, block: &Block) {
@@ -1218,7 +1224,8 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
     fn define_macro(&mut self, item: &ast::Item) -> MacroRulesScopeRef<'a> {
         let parent_scope = self.parent_scope;
         let expansion = parent_scope.expansion;
-        let def_id = self.r.local_def_id(item.id);
+        let feed = self.r.feed(item.id);
+        let def_id = feed.key();
         let (res, ident, span, macro_rules) = match &item.kind {
             ItemKind::MacroDef(def) => (self.res(def_id), item.ident, item.span, def.macro_rules),
             ItemKind::Fn(..) => match self.proc_macro_stub(item) {
@@ -1269,7 +1276,7 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
                 self.r.check_reserved_macro_name(ident, res);
                 self.insert_unused_macro(ident, def_id, item.id);
             }
-            self.r.feed_visibility(def_id, vis);
+            self.r.feed_visibility(feed, vis);
             let scope = self.r.arenas.alloc_macro_rules_scope(MacroRulesScope::Binding(
                 self.r.arenas.alloc_macro_rules_binding(MacroRulesBinding {
                     parent_macro_rules_scope: parent_scope.macro_rules,
@@ -1293,7 +1300,7 @@ impl<'a, 'b, 'tcx> BuildReducedGraphVisitor<'a, 'b, 'tcx> {
                 self.insert_unused_macro(ident, def_id, item.id);
             }
             self.r.define(module, ident, MacroNS, (res, vis, span, expansion));
-            self.r.feed_visibility(def_id, vis);
+            self.r.feed_visibility(feed, vis);
             self.parent_scope.macro_rules
         }
     }
@@ -1385,7 +1392,8 @@ impl<'a, 'b, 'tcx> Visitor<'b> for BuildReducedGraphVisitor<'a, 'b, 'tcx> {
         }
 
         let vis = self.resolve_visibility(&item.vis);
-        let local_def_id = self.r.local_def_id(item.id);
+        let feed = self.r.feed(item.id);
+        let local_def_id = feed.key();
         let def_id = local_def_id.to_def_id();
 
         if !(ctxt == AssocCtxt::Impl
@@ -1395,7 +1403,7 @@ impl<'a, 'b, 'tcx> Visitor<'b> for BuildReducedGraphVisitor<'a, 'b, 'tcx> {
             // Trait impl item visibility is inherited from its trait when not specified
             // explicitly. In that case we cannot determine it here in early resolve,
             // so we leave a hole in the visibility table to be filled later.
-            self.r.feed_visibility(local_def_id, vis);
+            self.r.feed_visibility(feed, vis);
         }
 
         if ctxt == AssocCtxt::Trait {
@@ -1469,7 +1477,7 @@ impl<'a, 'b, 'tcx> Visitor<'b> for BuildReducedGraphVisitor<'a, 'b, 'tcx> {
             self.visit_invoc(sf.id);
         } else {
             let vis = self.resolve_visibility(&sf.vis);
-            self.r.feed_visibility(self.r.local_def_id(sf.id), vis);
+            self.r.feed_visibility(self.r.feed(sf.id), vis);
             visit::walk_field_def(self, sf);
         }
     }
@@ -1487,10 +1495,11 @@ impl<'a, 'b, 'tcx> Visitor<'b> for BuildReducedGraphVisitor<'a, 'b, 'tcx> {
         let ident = variant.ident;
 
         // Define a name in the type namespace.
-        let def_id = self.r.local_def_id(variant.id);
+        let feed = self.r.feed(variant.id);
+        let def_id = feed.key();
         let vis = self.resolve_visibility(&variant.vis);
         self.r.define(parent, ident, TypeNS, (self.res(def_id), vis, variant.span, expn_id));
-        self.r.feed_visibility(def_id, vis);
+        self.r.feed_visibility(feed, vis);
 
         // If the variant is marked as non_exhaustive then lower the visibility to within the crate.
         let ctor_vis =
@@ -1502,10 +1511,11 @@ impl<'a, 'b, 'tcx> Visitor<'b> for BuildReducedGraphVisitor<'a, 'b, 'tcx> {
 
         // Define a constructor name in the value namespace.
         if let Some(ctor_node_id) = variant.data.ctor_node_id() {
-            let ctor_def_id = self.r.local_def_id(ctor_node_id);
+            let feed = self.r.feed(ctor_node_id);
+            let ctor_def_id = feed.key();
             let ctor_res = self.res(ctor_def_id);
             self.r.define(parent, ident, ValueNS, (ctor_res, ctor_vis, variant.span, expn_id));
-            self.r.feed_visibility(ctor_def_id, ctor_vis);
+            self.r.feed_visibility(feed, ctor_vis);
         }
 
         // Record field names for error reporting.
diff --git a/compiler/rustc_resolve/src/def_collector.rs b/compiler/rustc_resolve/src/def_collector.rs
index 12bf462a6fdfd..bb3b902c0de64 100644
--- a/compiler/rustc_resolve/src/def_collector.rs
+++ b/compiler/rustc_resolve/src/def_collector.rs
@@ -38,14 +38,16 @@ impl<'a, 'b, 'tcx> DefCollector<'a, 'b, 'tcx> {
             "create_def(node_id={:?}, def_kind={:?}, parent_def={:?})",
             node_id, def_kind, parent_def
         );
-        self.resolver.create_def(
-            parent_def,
-            node_id,
-            name,
-            def_kind,
-            self.expansion.to_expn_id(),
-            span.with_parent(None),
-        )
+        self.resolver
+            .create_def(
+                parent_def,
+                node_id,
+                name,
+                def_kind,
+                self.expansion.to_expn_id(),
+                span.with_parent(None),
+            )
+            .def_id()
     }
 
     fn with_parent<F: FnOnce(&mut Self)>(&mut self, parent_def: LocalDefId, f: F) {
diff --git a/compiler/rustc_resolve/src/late.rs b/compiler/rustc_resolve/src/late.rs
index 18abc5d22b711..455afb8de8eda 100644
--- a/compiler/rustc_resolve/src/late.rs
+++ b/compiler/rustc_resolve/src/late.rs
@@ -3121,7 +3121,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                 );
                 rustc_middle::ty::Visibility::Public
             };
-            this.r.feed_visibility(this.r.local_def_id(id), vis);
+            this.r.feed_visibility(this.r.feed(id), vis);
         };
 
         let Some(binding) = binding else {
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index 5de147c2b2444..ccb67ea78cfdb 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -52,8 +52,8 @@ use rustc_middle::metadata::ModChild;
 use rustc_middle::middle::privacy::EffectiveVisibilities;
 use rustc_middle::query::Providers;
 use rustc_middle::span_bug;
-use rustc_middle::ty::{self, MainDefinition, RegisteredTools, TyCtxt};
-use rustc_middle::ty::{ResolverGlobalCtxt, ResolverOutputs};
+use rustc_middle::ty::{self, MainDefinition, RegisteredTools, TyCtxt, TyCtxtFeed};
+use rustc_middle::ty::{Feed, ResolverGlobalCtxt, ResolverOutputs};
 use rustc_query_system::ich::StableHashingContext;
 use rustc_session::lint::builtin::PRIVATE_MACRO_USE;
 use rustc_session::lint::LintBuffer;
@@ -1117,7 +1117,7 @@ pub struct Resolver<'a, 'tcx> {
 
     next_node_id: NodeId,
 
-    node_id_to_def_id: NodeMap<LocalDefId>,
+    node_id_to_def_id: NodeMap<Feed<'tcx, LocalDefId>>,
     def_id_to_node_id: IndexVec<LocalDefId, ast::NodeId>,
 
     /// Indices of unnamed struct or variant fields with unresolved attributes.
@@ -1233,11 +1233,19 @@ impl<'a, 'tcx> AsMut<Resolver<'a, 'tcx>> for Resolver<'a, 'tcx> {
 
 impl<'tcx> Resolver<'_, 'tcx> {
     fn opt_local_def_id(&self, node: NodeId) -> Option<LocalDefId> {
-        self.node_id_to_def_id.get(&node).copied()
+        self.opt_feed(node).map(|f| f.key())
     }
 
     fn local_def_id(&self, node: NodeId) -> LocalDefId {
-        self.opt_local_def_id(node).unwrap_or_else(|| panic!("no entry for node id: `{node:?}`"))
+        self.feed(node).key()
+    }
+
+    fn opt_feed(&self, node: NodeId) -> Option<Feed<'tcx, LocalDefId>> {
+        self.node_id_to_def_id.get(&node).copied()
+    }
+
+    fn feed(&self, node: NodeId) -> Feed<'tcx, LocalDefId> {
+        self.opt_feed(node).unwrap_or_else(|| panic!("no entry for node id: `{node:?}`"))
     }
 
     fn local_def_kind(&self, node: NodeId) -> DefKind {
@@ -1253,18 +1261,19 @@ impl<'tcx> Resolver<'_, 'tcx> {
         def_kind: DefKind,
         expn_id: ExpnId,
         span: Span,
-    ) -> LocalDefId {
+    ) -> TyCtxtFeed<'tcx, LocalDefId> {
         let data = def_kind.def_path_data(name);
         assert!(
             !self.node_id_to_def_id.contains_key(&node_id),
             "adding a def'n for node-id {:?} and data {:?} but a previous def'n exists: {:?}",
             node_id,
             data,
-            self.tcx.definitions_untracked().def_key(self.node_id_to_def_id[&node_id]),
+            self.tcx.definitions_untracked().def_key(self.node_id_to_def_id[&node_id].key()),
         );
 
         // FIXME: remove `def_span` body, pass in the right spans here and call `tcx.at().create_def()`
-        let def_id = self.tcx.create_def(parent, name, def_kind).def_id();
+        let feed = self.tcx.create_def(parent, name, def_kind);
+        let def_id = feed.def_id();
 
         // Create the definition.
         if expn_id != ExpnId::root() {
@@ -1281,11 +1290,11 @@ impl<'tcx> Resolver<'_, 'tcx> {
         // we don't need a mapping from `NodeId` to `LocalDefId`.
         if node_id != ast::DUMMY_NODE_ID {
             debug!("create_def: def_id_to_node_id[{:?}] <-> {:?}", def_id, node_id);
-            self.node_id_to_def_id.insert(node_id, def_id);
+            self.node_id_to_def_id.insert(node_id, feed.downgrade());
         }
         assert_eq!(self.def_id_to_node_id.push(node_id), def_id);
 
-        def_id
+        feed
     }
 
     fn item_generics_num_lifetimes(&self, def_id: DefId) -> usize {
@@ -1333,7 +1342,11 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         let mut def_id_to_node_id = IndexVec::default();
         assert_eq!(def_id_to_node_id.push(CRATE_NODE_ID), CRATE_DEF_ID);
         let mut node_id_to_def_id = NodeMap::default();
-        node_id_to_def_id.insert(CRATE_NODE_ID, CRATE_DEF_ID);
+        let crate_feed = tcx.create_local_crate_def_id(crate_span);
+
+        crate_feed.def_kind(DefKind::Mod);
+        let crate_feed = crate_feed.downgrade();
+        node_id_to_def_id.insert(CRATE_NODE_ID, crate_feed);
 
         let mut invocation_parents = FxHashMap::default();
         invocation_parents.insert(LocalExpnId::ROOT, (CRATE_DEF_ID, ImplTraitContext::Existential));
@@ -1484,7 +1497,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
 
         let root_parent_scope = ParentScope::module(graph_root, &resolver);
         resolver.invocation_parent_scopes.insert(LocalExpnId::ROOT, root_parent_scope);
-        resolver.feed_visibility(CRATE_DEF_ID, ty::Visibility::Public);
+        resolver.feed_visibility(crate_feed, ty::Visibility::Public);
 
         resolver
     }
@@ -1532,9 +1545,10 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         Default::default()
     }
 
-    fn feed_visibility(&mut self, def_id: LocalDefId, vis: ty::Visibility) {
-        self.tcx.feed_local_def_id(def_id).visibility(vis.to_def_id());
-        self.visibilities_for_hashing.push((def_id, vis));
+    fn feed_visibility(&mut self, feed: Feed<'tcx, LocalDefId>, vis: ty::Visibility) {
+        let feed = feed.upgrade(self.tcx);
+        feed.visibility(vis.to_def_id());
+        self.visibilities_for_hashing.push((feed.def_id(), vis));
     }
 
     pub fn into_outputs(self) -> ResolverOutputs {
@@ -1547,12 +1561,16 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         let confused_type_with_std_module = self.confused_type_with_std_module;
         let effective_visibilities = self.effective_visibilities;
 
-        self.tcx.feed_local_crate().stripped_cfg_items(self.tcx.arena.alloc_from_iter(
-            self.stripped_cfg_items.into_iter().filter_map(|item| {
-                let parent_module = self.node_id_to_def_id.get(&item.parent_module)?.to_def_id();
-                Some(StrippedCfgItem { parent_module, name: item.name, cfg: item.cfg })
-            }),
-        ));
+        let stripped_cfg_items = Steal::new(
+            self.stripped_cfg_items
+                .into_iter()
+                .filter_map(|item| {
+                    let parent_module =
+                        self.node_id_to_def_id.get(&item.parent_module)?.key().to_def_id();
+                    Some(StrippedCfgItem { parent_module, name: item.name, cfg: item.cfg })
+                })
+                .collect(),
+        );
 
         let global_ctxt = ResolverGlobalCtxt {
             expn_that_defined,
@@ -1569,6 +1587,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             doc_link_resolutions: self.doc_link_resolutions,
             doc_link_traits_in_scope: self.doc_link_traits_in_scope,
             all_macro_rules: self.all_macro_rules,
+            stripped_cfg_items,
         };
         let ast_lowering = ty::ResolverAstLowering {
             legacy_const_generic_args: self.legacy_const_generic_args,
@@ -1578,7 +1597,11 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             lifetimes_res_map: self.lifetimes_res_map,
             extra_lifetime_params_map: self.extra_lifetime_params_map,
             next_node_id: self.next_node_id,
-            node_id_to_def_id: self.node_id_to_def_id,
+            node_id_to_def_id: self
+                .node_id_to_def_id
+                .into_items()
+                .map(|(k, f)| (k, f.key()))
+                .collect(),
             def_id_to_node_id: self.def_id_to_node_id,
             trait_map: self.trait_map,
             lifetime_elision_allowed: self.lifetime_elision_allowed,
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 7b735d48bdfce..0f7885769c267 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -202,6 +202,7 @@
 //
 // Language features:
 // tidy-alphabetical-start
+#![cfg_attr(bootstrap, feature(diagnostic_namespace))]
 #![cfg_attr(bootstrap, feature(platform_intrinsics))]
 #![feature(abi_unadjusted)]
 #![feature(adt_const_params)]
@@ -223,7 +224,6 @@
 #![feature(const_trait_impl)]
 #![feature(decl_macro)]
 #![feature(deprecated_suggestion)]
-#![feature(diagnostic_namespace)]
 #![feature(doc_cfg)]
 #![feature(doc_cfg_hide)]
 #![feature(doc_notable_trait)]
diff --git a/library/std/src/os/unix/mod.rs b/library/std/src/os/unix/mod.rs
index 5ba8719e6ffeb..b0633fd7bfccb 100644
--- a/library/std/src/os/unix/mod.rs
+++ b/library/std/src/os/unix/mod.rs
@@ -95,22 +95,6 @@ pub mod process;
 pub mod raw;
 pub mod thread;
 
-#[unstable(feature = "peer_credentials_unix_socket", issue = "42839", reason = "unstable")]
-#[cfg(any(
-    target_os = "android",
-    target_os = "linux",
-    target_os = "dragonfly",
-    target_os = "freebsd",
-    target_os = "ios",
-    target_os = "tvos",
-    target_os = "watchos",
-    target_os = "macos",
-    target_os = "netbsd",
-    target_os = "openbsd",
-    target_os = "nto",
-))]
-pub mod ucred;
-
 /// A prelude for conveniently writing platform-specific code.
 ///
 /// Includes all extension traits, and some important type definitions.
diff --git a/library/std/src/os/unix/net/mod.rs b/library/std/src/os/unix/net/mod.rs
index 6da3e350bf12f..28c1188677b6e 100644
--- a/library/std/src/os/unix/net/mod.rs
+++ b/library/std/src/os/unix/net/mod.rs
@@ -12,6 +12,20 @@ mod listener;
 mod stream;
 #[cfg(all(test, not(target_os = "emscripten")))]
 mod tests;
+#[cfg(any(
+    target_os = "android",
+    target_os = "linux",
+    target_os = "dragonfly",
+    target_os = "freebsd",
+    target_os = "ios",
+    target_os = "tvos",
+    target_os = "watchos",
+    target_os = "macos",
+    target_os = "netbsd",
+    target_os = "openbsd",
+    target_os = "nto",
+))]
+mod ucred;
 
 #[stable(feature = "unix_socket", since = "1.10.0")]
 pub use self::addr::*;
@@ -24,3 +38,18 @@ pub use self::datagram::*;
 pub use self::listener::*;
 #[stable(feature = "unix_socket", since = "1.10.0")]
 pub use self::stream::*;
+#[cfg(any(
+    target_os = "android",
+    target_os = "linux",
+    target_os = "dragonfly",
+    target_os = "freebsd",
+    target_os = "ios",
+    target_os = "tvos",
+    target_os = "watchos",
+    target_os = "macos",
+    target_os = "netbsd",
+    target_os = "openbsd",
+    target_os = "nto",
+))]
+#[unstable(feature = "peer_credentials_unix_socket", issue = "42839", reason = "unstable")]
+pub use self::ucred::*;
diff --git a/library/std/src/os/unix/net/stream.rs b/library/std/src/os/unix/net/stream.rs
index b1cd504e21939..069cb299e287c 100644
--- a/library/std/src/os/unix/net/stream.rs
+++ b/library/std/src/os/unix/net/stream.rs
@@ -1,10 +1,3 @@
-#[cfg(any(doc, target_os = "android", target_os = "linux"))]
-use super::{recv_vectored_with_ancillary_from, send_vectored_with_ancillary_to, SocketAncillary};
-use super::{sockaddr_un, SocketAddr};
-use crate::fmt;
-use crate::io::{self, IoSlice, IoSliceMut};
-use crate::net::Shutdown;
-use crate::os::unix::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, OwnedFd, RawFd};
 #[cfg(any(
     target_os = "android",
     target_os = "linux",
@@ -17,28 +10,20 @@ use crate::os::unix::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, Owned
     target_os = "netbsd",
     target_os = "openbsd"
 ))]
-use crate::os::unix::ucred;
+use super::{peer_cred, UCred};
+#[cfg(any(doc, target_os = "android", target_os = "linux"))]
+use super::{recv_vectored_with_ancillary_from, send_vectored_with_ancillary_to, SocketAncillary};
+use super::{sockaddr_un, SocketAddr};
+use crate::fmt;
+use crate::io::{self, IoSlice, IoSliceMut};
+use crate::net::Shutdown;
+use crate::os::unix::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, OwnedFd, RawFd};
 use crate::path::Path;
 use crate::sys::cvt;
 use crate::sys::net::Socket;
 use crate::sys_common::{AsInner, FromInner};
 use crate::time::Duration;
 
-#[unstable(feature = "peer_credentials_unix_socket", issue = "42839", reason = "unstable")]
-#[cfg(any(
-    target_os = "android",
-    target_os = "linux",
-    target_os = "dragonfly",
-    target_os = "freebsd",
-    target_os = "ios",
-    target_os = "tvos",
-    target_os = "macos",
-    target_os = "watchos",
-    target_os = "netbsd",
-    target_os = "openbsd"
-))]
-pub use ucred::UCred;
-
 /// A Unix stream socket.
 ///
 /// # Examples
@@ -247,7 +232,7 @@ impl UnixStream {
         target_os = "openbsd"
     ))]
     pub fn peer_cred(&self) -> io::Result<UCred> {
-        ucred::peer_cred(self)
+        peer_cred(self)
     }
 
     /// Sets the read timeout for the socket.
diff --git a/library/std/src/os/unix/ucred.rs b/library/std/src/os/unix/net/ucred.rs
similarity index 95%
rename from library/std/src/os/unix/ucred.rs
rename to library/std/src/os/unix/net/ucred.rs
index 6efa74182cc0b..de09c93840a54 100644
--- a/library/std/src/os/unix/ucred.rs
+++ b/library/std/src/os/unix/net/ucred.rs
@@ -1,5 +1,3 @@
-//! Unix peer credentials.
-
 // NOTE: Code in this file is heavily based on work done in PR 13 from the tokio-uds repository on
 //       GitHub.
 //
@@ -26,7 +24,7 @@ pub struct UCred {
 }
 
 #[cfg(any(target_os = "android", target_os = "linux"))]
-pub use self::impl_linux::peer_cred;
+pub(super) use self::impl_linux::peer_cred;
 
 #[cfg(any(
     target_os = "dragonfly",
@@ -34,13 +32,13 @@ pub use self::impl_linux::peer_cred;
     target_os = "openbsd",
     target_os = "netbsd"
 ))]
-pub use self::impl_bsd::peer_cred;
+pub(super) use self::impl_bsd::peer_cred;
 
 #[cfg(any(target_os = "macos", target_os = "ios", target_os = "tvos", target_os = "watchos"))]
-pub use self::impl_mac::peer_cred;
+pub(super) use self::impl_mac::peer_cred;
 
 #[cfg(any(target_os = "linux", target_os = "android"))]
-pub mod impl_linux {
+mod impl_linux {
     use super::UCred;
     use crate::os::unix::io::AsRawFd;
     use crate::os::unix::net::UnixStream;
@@ -82,7 +80,7 @@ pub mod impl_linux {
     target_os = "netbsd",
     target_os = "nto",
 ))]
-pub mod impl_bsd {
+mod impl_bsd {
     use super::UCred;
     use crate::io;
     use crate::os::unix::io::AsRawFd;
@@ -99,7 +97,7 @@ pub mod impl_bsd {
 }
 
 #[cfg(any(target_os = "macos", target_os = "ios", target_os = "tvos", target_os = "watchos"))]
-pub mod impl_mac {
+mod impl_mac {
     use super::UCred;
     use crate::os::unix::io::AsRawFd;
     use crate::os::unix::net::UnixStream;
diff --git a/library/std/src/os/unix/ucred/tests.rs b/library/std/src/os/unix/net/ucred/tests.rs
similarity index 100%
rename from library/std/src/os/unix/ucred/tests.rs
rename to library/std/src/os/unix/net/ucred/tests.rs
diff --git a/src/bootstrap/src/core/build_steps/dist.rs b/src/bootstrap/src/core/build_steps/dist.rs
index c8c32fb8699f5..1090edc9c927e 100644
--- a/src/bootstrap/src/core/build_steps/dist.rs
+++ b/src/bootstrap/src/core/build_steps/dist.rs
@@ -2047,7 +2047,15 @@ fn install_llvm_file(
             // projects like miri link against librustc_driver.so. We don't use a symlink, as
             // these are not allowed inside rustup components.
             let link = t!(fs::read_link(source));
-            t!(std::fs::write(full_dest, format!("INPUT({})\n", link.display())));
+            let mut linker_script = t!(fs::File::create(full_dest));
+            t!(write!(linker_script, "INPUT({})\n", link.display()));
+
+            // We also want the linker script to have the same mtime as the source, otherwise it
+            // can trigger rebuilds.
+            let meta = t!(fs::metadata(source));
+            if let Ok(mtime) = meta.modified() {
+                t!(linker_script.set_modified(mtime));
+            }
         }
     } else {
         builder.install(&source, destination, 0o644);
diff --git a/src/doc/rust.css b/src/doc/rust.css
index e0bf64c33bcf0..bd2e0b9451870 100644
--- a/src/doc/rust.css
+++ b/src/doc/rust.css
@@ -5,12 +5,13 @@ body {
 	margin: 0 auto;
 	padding: 0 15px;
 	font-size: 18px;
-	color: #333;
+	color: #000;
 	line-height: 1.428571429;
 
 	-webkit-box-sizing: unset;
 	-moz-box-sizing: unset;
 	box-sizing: unset;
+	background: #fff;
 }
 @media (min-width: 768px) {
 	body {
@@ -39,7 +40,6 @@ h4, h5, h6 {
 	padding: 5px 10px;
 }
 h5, h6 {
-	color: black;
 	text-decoration: underline;
 }
 
diff --git a/src/doc/unstable-book/src/language-features/diagnostic-namespace.md b/src/doc/unstable-book/src/language-features/diagnostic-namespace.md
deleted file mode 100644
index 7c46811a27ab8..0000000000000
--- a/src/doc/unstable-book/src/language-features/diagnostic-namespace.md
+++ /dev/null
@@ -1,84 +0,0 @@
-# `diagnostic_namespace`
-
-The tracking issue for this feature is: [#111996]
-
-[#111996]: https://github.com/rust-lang/rust/issues/111996
-
-------------------------
-
-The `diagnostic_namespace` feature permits customization of compilation errors.
-
-## diagnostic::on_unimplemented
-
-With [#114452] support for `diagnostic::on_unimplemented` was added.
-
-When used on a trait declaration, the following options are available:
-
-* `message` to customize the primary error message
-* `note` to add a customized note message to an error message
-* `label` to customize the label part of the error message
-
-The attribute will hint to the compiler to use these in error messages:
-```rust
-// some library
-#![feature(diagnostic_namespace)]
-
-#[diagnostic::on_unimplemented(
-    message = "cannot insert element",
-    label = "cannot be put into a table",
-    note = "see <link> for more information about the Table api"
-)]
-pub trait Element {
-    // ...
-}
-```
-
-```rust,compile_fail,E0277
-# #![feature(diagnostic_namespace)]
-#
-# #[diagnostic::on_unimplemented(
-#    message = "cannot insert element",
-#    label = "cannot be put into a table",
-#    note = "see <link> for more information about the Table api"
-# )]
-# pub trait Element {
-#    // ...
-# }
-# struct Table;
-# impl Table {
-#    fn insert<T: Element>(&self, element: T) {
-#        // ..
-#    }
-# }
-# fn main() {
-#    let table = Table;
-#    let element = ();
-// user code
-table.insert(element);
-# }
-```
-
-```text
-error[E0277]: cannot insert element
-  --> src/main.rs:24:18
-   |
-24 |     table.insert(element);
-   |           ------ ^^^^^^^ cannot be put into a table
-   |           |
-   |           required by a bound introduced by this call
-   |
-   = help: the trait `Element` is not implemented for `<type>`
-   = note: see <link> for more information about the Table api
-note: required by a bound in `Table::insert`
-  --> src/main.rs:15:18
-   |
-15 |     fn insert<T: Element>(&self, element: T) {
-   |                  ^^^^^^^ required by this bound in `Table::insert`
-
-For more information about this error, try `rustc --explain E0277`.
-```
-
-See [RFC 3368] for more information.
-
-[#114452]: https://github.com/rust-lang/rust/pull/114452
-[RFC 3368]: https://github.com/rust-lang/rfcs/blob/master/text/3368-diagnostic-attribute-namespace.md
diff --git a/src/tools/opt-dist/src/utils/artifact_size.rs b/src/tools/opt-dist/src/utils/artifact_size.rs
index 757f6d497095c..b6c453fb40bd3 100644
--- a/src/tools/opt-dist/src/utils/artifact_size.rs
+++ b/src/tools/opt-dist/src/utils/artifact_size.rs
@@ -15,21 +15,8 @@ pub fn print_binary_sizes(env: &Environment) -> anyhow::Result<()> {
 
     let root = env.build_artifacts().join("stage2");
 
-    let all_lib_files = get_files_from_dir(&root.join("lib"), None)?;
-
     let mut files = get_files_from_dir(&root.join("bin"), None)?;
-    files.extend(get_files_from_dir(&root.join("lib"), Some(".so"))?);
-
-    // libLLVM.so can be named libLLVM.so.<suffix>, so we try to explicitly add it here if it
-    // wasn't found by the above call.
-    if !files.iter().any(|f| f.file_name().unwrap_or_default().starts_with("libLLVM")) {
-        if let Some(llvm_lib) =
-            all_lib_files.iter().find(|f| f.file_name().unwrap_or_default().starts_with("libLLVM"))
-        {
-            files.push(llvm_lib.clone());
-        }
-    }
-
+    files.extend(get_files_from_dir(&root.join("lib"), None)?);
     files.sort_unstable();
 
     let items: Vec<_> = files
diff --git a/tests/ui/diagnostic_namespace/existing_proc_macros.rs b/tests/ui/diagnostic_namespace/existing_proc_macros.rs
index 2bc58aea8fc2c..014ec46f1b981 100644
--- a/tests/ui/diagnostic_namespace/existing_proc_macros.rs
+++ b/tests/ui/diagnostic_namespace/existing_proc_macros.rs
@@ -1,4 +1,3 @@
-#![feature(diagnostic_namespace)]
 //@ check-pass
 //@ aux-build:proc-macro-helper.rs
 
diff --git a/tests/ui/diagnostic_namespace/feature-gate-diagnostic_namespace.rs b/tests/ui/diagnostic_namespace/feature-gate-diagnostic_namespace.rs
deleted file mode 100644
index b08e291621fdc..0000000000000
--- a/tests/ui/diagnostic_namespace/feature-gate-diagnostic_namespace.rs
+++ /dev/null
@@ -1,13 +0,0 @@
-#[diagnostic::non_existing_attribute]
-//~^ERROR `#[diagnostic]` attribute name space is experimental [E0658]
-//~|WARNING unknown diagnostic attribute [unknown_or_malformed_diagnostic_attributes]
-pub trait Bar {
-}
-
-#[diagnostic::non_existing_attribute(with_option = "foo")]
-//~^ERROR `#[diagnostic]` attribute name space is experimental [E0658]
-//~|WARNING unknown diagnostic attribute [unknown_or_malformed_diagnostic_attributes]
-struct Foo;
-
-fn main() {
-}
diff --git a/tests/ui/diagnostic_namespace/feature-gate-diagnostic_namespace.stderr b/tests/ui/diagnostic_namespace/feature-gate-diagnostic_namespace.stderr
deleted file mode 100644
index 38424c13d8613..0000000000000
--- a/tests/ui/diagnostic_namespace/feature-gate-diagnostic_namespace.stderr
+++ /dev/null
@@ -1,37 +0,0 @@
-error[E0658]: `#[diagnostic]` attribute name space is experimental
-  --> $DIR/feature-gate-diagnostic_namespace.rs:1:3
-   |
-LL | #[diagnostic::non_existing_attribute]
-   |   ^^^^^^^^^^
-   |
-   = note: see issue #111996 <https://github.com/rust-lang/rust/issues/111996> for more information
-   = help: add `#![feature(diagnostic_namespace)]` 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[E0658]: `#[diagnostic]` attribute name space is experimental
-  --> $DIR/feature-gate-diagnostic_namespace.rs:7:3
-   |
-LL | #[diagnostic::non_existing_attribute(with_option = "foo")]
-   |   ^^^^^^^^^^
-   |
-   = note: see issue #111996 <https://github.com/rust-lang/rust/issues/111996> for more information
-   = help: add `#![feature(diagnostic_namespace)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
-warning: unknown diagnostic attribute
-  --> $DIR/feature-gate-diagnostic_namespace.rs:1:15
-   |
-LL | #[diagnostic::non_existing_attribute]
-   |               ^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `#[warn(unknown_or_malformed_diagnostic_attributes)]` on by default
-
-warning: unknown diagnostic attribute
-  --> $DIR/feature-gate-diagnostic_namespace.rs:7:15
-   |
-LL | #[diagnostic::non_existing_attribute(with_option = "foo")]
-   |               ^^^^^^^^^^^^^^^^^^^^^^
-
-error: aborting due to 2 previous errors; 2 warnings emitted
-
-For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/diagnostic_namespace/non_existing_attributes_accepted.rs b/tests/ui/diagnostic_namespace/non_existing_attributes_accepted.rs
index 95465701bf858..f6957b1448d18 100644
--- a/tests/ui/diagnostic_namespace/non_existing_attributes_accepted.rs
+++ b/tests/ui/diagnostic_namespace/non_existing_attributes_accepted.rs
@@ -1,4 +1,3 @@
-#![feature(diagnostic_namespace)]
 //@ check-pass
 #[diagnostic::non_existing_attribute]
 //~^WARN unknown diagnostic attribute
diff --git a/tests/ui/diagnostic_namespace/non_existing_attributes_accepted.stderr b/tests/ui/diagnostic_namespace/non_existing_attributes_accepted.stderr
index 753077b365e8f..c073ec9b103f6 100644
--- a/tests/ui/diagnostic_namespace/non_existing_attributes_accepted.stderr
+++ b/tests/ui/diagnostic_namespace/non_existing_attributes_accepted.stderr
@@ -1,5 +1,5 @@
 warning: unknown diagnostic attribute
-  --> $DIR/non_existing_attributes_accepted.rs:3:15
+  --> $DIR/non_existing_attributes_accepted.rs:2:15
    |
 LL | #[diagnostic::non_existing_attribute]
    |               ^^^^^^^^^^^^^^^^^^^^^^
@@ -7,7 +7,7 @@ LL | #[diagnostic::non_existing_attribute]
    = note: `#[warn(unknown_or_malformed_diagnostic_attributes)]` on by default
 
 warning: unknown diagnostic attribute
-  --> $DIR/non_existing_attributes_accepted.rs:8:15
+  --> $DIR/non_existing_attributes_accepted.rs:7:15
    |
 LL | #[diagnostic::non_existing_attribute(with_option = "foo")]
    |               ^^^^^^^^^^^^^^^^^^^^^^
diff --git a/tests/ui/diagnostic_namespace/on_unimplemented/auxiliary/other.rs b/tests/ui/diagnostic_namespace/on_unimplemented/auxiliary/other.rs
index 884bab2800a5b..512ef6330e5ec 100644
--- a/tests/ui/diagnostic_namespace/on_unimplemented/auxiliary/other.rs
+++ b/tests/ui/diagnostic_namespace/on_unimplemented/auxiliary/other.rs
@@ -1,5 +1,3 @@
-#![feature(diagnostic_namespace)]
-
 #[diagnostic::on_unimplemented(
     message = "Message",
     note = "Note",
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 eb985c062f3dd..30a85ff21992d 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
@@ -1,5 +1,3 @@
-#![feature(diagnostic_namespace)]
-
 #[diagnostic::on_unimplemented(
     on(_Self = "&str"),
     //~^WARN malformed `on_unimplemented` attribute
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 75a701f0b5f65..e34b917f67e10 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
@@ -1,5 +1,5 @@
 warning: `#[diagnostic::on_unimplemented]` can only be applied to trait definitions
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:24:1
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:22:1
    |
 LL | #[diagnostic::on_unimplemented(message = "Not allowed to apply it on a impl")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -7,7 +7,7 @@ LL | #[diagnostic::on_unimplemented(message = "Not allowed to apply it on a impl
    = note: `#[warn(unknown_or_malformed_diagnostic_attributes)]` on by default
 
 warning: malformed `on_unimplemented` attribute
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:4:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:2:5
    |
 LL |     on(_Self = "&str"),
    |     ^^^^^^^^^^^^^^^^^^ invalid option found here
@@ -15,7 +15,7 @@ LL |     on(_Self = "&str"),
    = help: only `message`, `note` and `label` are allowed as options
 
 warning: malformed `on_unimplemented` attribute
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:10:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:8:5
    |
 LL |     parent_label = "in this scope",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ invalid option found here
@@ -23,7 +23,7 @@ LL |     parent_label = "in this scope",
    = help: only `message`, `note` and `label` are allowed as options
 
 warning: malformed `on_unimplemented` attribute
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:13:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:11:5
    |
 LL |     append_const_msg
    |     ^^^^^^^^^^^^^^^^ invalid option found here
@@ -31,7 +31,7 @@ LL |     append_const_msg
    = help: only `message`, `note` and `label` are allowed as options
 
 warning: malformed `on_unimplemented` attribute
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:19:32
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:17:32
    |
 LL | #[diagnostic::on_unimplemented = "Message"]
    |                                ^^^^^^^^^^^ invalid option found here
@@ -39,7 +39,7 @@ LL | #[diagnostic::on_unimplemented = "Message"]
    = help: only `message`, `note` and `label` are allowed as options
 
 warning: there is no parameter `from_desugaring` on trait `Baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:31:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:29:5
    |
 LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -47,7 +47,7 @@ LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
    = help: expect either a generic argument name or `{Self}` as format argument
 
 warning: there is no parameter `direct` on trait `Baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:31:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:29:5
    |
 LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -55,7 +55,7 @@ LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
    = help: expect either a generic argument name or `{Self}` as format argument
 
 warning: there is no parameter `cause` on trait `Baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:31:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:29:5
    |
 LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -63,7 +63,7 @@ LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
    = help: expect either a generic argument name or `{Self}` as format argument
 
 warning: there is no parameter `integral` on trait `Baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:31:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:29:5
    |
 LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -71,7 +71,7 @@ LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
    = help: expect either a generic argument name or `{Self}` as format argument
 
 warning: there is no parameter `integer` on trait `Baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:31:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:29:5
    |
 LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -79,7 +79,7 @@ LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
    = help: expect either a generic argument name or `{Self}` as format argument
 
 warning: there is no parameter `float` on trait `Baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:42:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:40:5
    |
 LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -87,7 +87,7 @@ LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
    = help: expect either a generic argument name or `{Self}` as format argument
 
 warning: there is no parameter `_Self` on trait `Baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:42:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:40:5
    |
 LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -95,7 +95,7 @@ LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
    = help: expect either a generic argument name or `{Self}` as format argument
 
 warning: there is no parameter `crate_local` on trait `Baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:42:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:40:5
    |
 LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -103,7 +103,7 @@ LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
    = help: expect either a generic argument name or `{Self}` as format argument
 
 warning: there is no parameter `Trait` on trait `Baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:42:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:40:5
    |
 LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -111,7 +111,7 @@ LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
    = help: expect either a generic argument name or `{Self}` as format argument
 
 warning: there is no parameter `ItemContext` on trait `Baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:42:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:40:5
    |
 LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -119,7 +119,7 @@ LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
    = 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:4:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:2:5
    |
 LL |     on(_Self = "&str"),
    |     ^^^^^^^^^^^^^^^^^^ invalid option found here
@@ -128,7 +128,7 @@ LL |     on(_Self = "&str"),
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 warning: malformed `on_unimplemented` attribute
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:10:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:8:5
    |
 LL |     parent_label = "in this scope",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ invalid option found here
@@ -137,7 +137,7 @@ LL |     parent_label = "in this scope",
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 warning: malformed `on_unimplemented` attribute
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:13:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:11:5
    |
 LL |     append_const_msg
    |     ^^^^^^^^^^^^^^^^ invalid option found here
@@ -146,7 +146,7 @@ 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:61:15
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:59:15
    |
 LL |     takes_foo(());
    |     --------- ^^ trait has `()` and `i32` as params
@@ -156,18 +156,18 @@ LL |     takes_foo(());
    = help: the trait `Foo<i32>` is not implemented for `()`
    = note: trait has `()` and `i32` as params
 help: this trait has no implementations, consider adding one
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:17:1
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:15:1
    |
 LL | trait Foo<T> {}
    | ^^^^^^^^^^^^
 note: required by a bound in `takes_foo`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:56:22
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:54:22
    |
 LL | fn takes_foo(_: impl Foo<i32>) {}
    |                      ^^^^^^^^ required by this bound in `takes_foo`
 
 warning: malformed `on_unimplemented` attribute
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:19:32
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:17:32
    |
 LL | #[diagnostic::on_unimplemented = "Message"]
    |                                ^^^^^^^^^^^ invalid option found here
@@ -176,7 +176,7 @@ 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:63:15
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:61:15
    |
 LL |     takes_bar(());
    |     --------- ^^ the trait `Bar` is not implemented for `()`
@@ -185,13 +185,13 @@ 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:57:22
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:55:22
    |
 LL | fn takes_bar(_: impl Bar) {}
    |                      ^^^ required by this bound in `takes_bar`
 
 warning: there is no parameter `from_desugaring` on trait `Baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:31:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:29:5
    |
 LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -200,7 +200,7 @@ LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 warning: there is no parameter `direct` on trait `Baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:31:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:29:5
    |
 LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -209,7 +209,7 @@ LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 warning: there is no parameter `cause` on trait `Baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:31:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:29:5
    |
 LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -218,7 +218,7 @@ LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 warning: there is no parameter `integral` on trait `Baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:31:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:29:5
    |
 LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -227,7 +227,7 @@ LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 warning: there is no parameter `integer` on trait `Baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:31:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:29:5
    |
 LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -236,7 +236,7 @@ LL |     message = "{from_desugaring}{direct}{cause}{integral}{integer}",
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 warning: there is no parameter `float` on trait `Baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:42:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:40:5
    |
 LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -245,7 +245,7 @@ LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 warning: there is no parameter `_Self` on trait `Baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:42:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:40:5
    |
 LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -254,7 +254,7 @@ LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 warning: there is no parameter `crate_local` on trait `Baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:42:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:40:5
    |
 LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -263,7 +263,7 @@ LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 warning: there is no parameter `Trait` on trait `Baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:42:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:40:5
    |
 LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -272,7 +272,7 @@ LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 warning: there is no parameter `ItemContext` on trait `Baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:42:5
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:40:5
    |
 LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -281,7 +281,7 @@ LL |     label = "{float}{_Self}{crate_local}{Trait}{ItemContext}"
    = 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:65:15
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:63:15
    |
 LL |     takes_baz(());
    |     --------- ^^ {float}{_Self}{crate_local}{Trait}{ItemContext}
@@ -290,12 +290,12 @@ LL |     takes_baz(());
    |
    = 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:54:1
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:52:1
    |
 LL | trait Baz {}
    | ^^^^^^^^^
 note: required by a bound in `takes_baz`
-  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:58:22
+  --> $DIR/do_not_accept_options_of_the_internal_rustc_attribute.rs:56:22
    |
 LL | fn takes_baz(_: impl Baz) {}
    |                      ^^^ required by this bound in `takes_baz`
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 12fe988170ac1..b4234066bb19a 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
@@ -1,5 +1,3 @@
-#![feature(diagnostic_namespace)]
-
 #[diagnostic::on_unimplemented(unsupported = "foo")]
 //~^WARN malformed `on_unimplemented` attribute
 //~|WARN malformed `on_unimplemented` attribute
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 11263580b15e2..dc0c194823696 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
@@ -1,5 +1,5 @@
 warning: `#[diagnostic::on_unimplemented]` can only be applied to trait definitions
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:8:1
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:6:1
    |
 LL | #[diagnostic::on_unimplemented(message = "Baz")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -7,7 +7,7 @@ LL | #[diagnostic::on_unimplemented(message = "Baz")]
    = note: `#[warn(unknown_or_malformed_diagnostic_attributes)]` on by default
 
 warning: malformed `on_unimplemented` attribute
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:3:32
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:1:32
    |
 LL | #[diagnostic::on_unimplemented(unsupported = "foo")]
    |                                ^^^^^^^^^^^^^^^^^^^ invalid option found here
@@ -15,7 +15,7 @@ LL | #[diagnostic::on_unimplemented(unsupported = "foo")]
    = 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:12:50
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:10:50
    |
 LL | #[diagnostic::on_unimplemented(message = "Boom", unsupported = "Bar")]
    |                                                  ^^^^^^^^^^^^^^^^^^^ invalid option found here
@@ -23,7 +23,7 @@ LL | #[diagnostic::on_unimplemented(message = "Boom", unsupported = "Bar")]
    = 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:17:50
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:15:50
    |
 LL | #[diagnostic::on_unimplemented(message = "Boom", on(_Self = "i32", message = "whatever"))]
    |                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ invalid option found here
@@ -31,7 +31,7 @@ LL | #[diagnostic::on_unimplemented(message = "Boom", on(_Self = "i32", message
    = 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:20:32
    |
 LL | #[diagnostic::on_unimplemented = "boom"]
    |                                ^^^^^^^^ invalid option found here
@@ -39,7 +39,7 @@ 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:24:1
    |
 LL | #[diagnostic::on_unimplemented]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -47,7 +47,7 @@ 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:31:32
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:29:32
    |
 LL | #[diagnostic::on_unimplemented(message = "{DoesNotExist}")]
    |                                ^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -55,7 +55,7 @@ LL | #[diagnostic::on_unimplemented(message = "{DoesNotExist}")]
    = help: expect either a generic argument name or `{Self}` as format argument
 
 warning: malformed `on_unimplemented` attribute
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:3:32
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:1:32
    |
 LL | #[diagnostic::on_unimplemented(unsupported = "foo")]
    |                                ^^^^^^^^^^^^^^^^^^^ invalid option found here
@@ -64,7 +64,7 @@ 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:41:14
    |
 LL |     take_foo(1_i32);
    |     -------- ^^^^^ the trait `Foo` is not implemented for `i32`
@@ -72,18 +72,18 @@ LL |     take_foo(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:6:1
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:4:1
    |
 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:34:21
    |
 LL | fn take_foo(_: impl Foo) {}
    |                     ^^^ required by this bound in `take_foo`
 
 warning: malformed `on_unimplemented` attribute
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:12:50
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:10:50
    |
 LL | #[diagnostic::on_unimplemented(message = "Boom", unsupported = "Bar")]
    |                                                  ^^^^^^^^^^^^^^^^^^^ invalid option found here
@@ -92,7 +92,7 @@ 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:43:14
    |
 LL |     take_baz(1_i32);
    |     -------- ^^^^^ the trait `Baz` is not implemented for `i32`
@@ -100,18 +100,18 @@ LL |     take_baz(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:15:1
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:13:1
    |
 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:35:21
    |
 LL | fn take_baz(_: impl Baz) {}
    |                     ^^^ required by this bound in `take_baz`
 
 warning: malformed `on_unimplemented` attribute
-  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:17:50
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:15:50
    |
 LL | #[diagnostic::on_unimplemented(message = "Boom", on(_Self = "i32", message = "whatever"))]
    |                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ invalid option found here
@@ -120,7 +120,7 @@ LL | #[diagnostic::on_unimplemented(message = "Boom", on(_Self = "i32", message
    = 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:45:15
    |
 LL |     take_boom(1_i32);
    |     --------- ^^^^^ the trait `Boom` is not implemented for `i32`
@@ -128,18 +128,18 @@ LL |     take_boom(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:20:1
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:18:1
    |
 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:36:22
    |
 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:24:1
    |
 LL | #[diagnostic::on_unimplemented]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -148,7 +148,7 @@ 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:47:19
    |
 LL |     take_whatever(1_i32);
    |     ------------- ^^^^^ the trait `Whatever` is not implemented for `i32`
@@ -156,18 +156,18 @@ 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:27:1
    |
 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:37:26
    |
 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:31:32
+  --> $DIR/do_not_fail_parsing_on_invalid_options_1.rs:29:32
    |
 LL | #[diagnostic::on_unimplemented(message = "{DoesNotExist}")]
    |                                ^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -176,7 +176,7 @@ 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:49:15
    |
 LL |     take_test(());
    |     --------- ^^ the trait `Test` is not implemented for `()`
@@ -184,12 +184,12 @@ 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:32:1
    |
 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:38:22
    |
 LL | fn take_test(_: impl Test) {}
    |                      ^^^^ required by this bound in `take_test`
diff --git a/tests/ui/diagnostic_namespace/on_unimplemented/feature-gate-diagnostic_on_unimplemented.rs b/tests/ui/diagnostic_namespace/on_unimplemented/feature-gate-diagnostic_on_unimplemented.rs
deleted file mode 100644
index 609a840c118c6..0000000000000
--- a/tests/ui/diagnostic_namespace/on_unimplemented/feature-gate-diagnostic_on_unimplemented.rs
+++ /dev/null
@@ -1,7 +0,0 @@
-#[diagnostic::on_unimplemented(message = "Foo")]
-//~^ERROR `#[diagnostic]` attribute name space is experimental [E0658]
-pub trait Bar {
-}
-
-fn main() {
-}
diff --git a/tests/ui/diagnostic_namespace/on_unimplemented/feature-gate-diagnostic_on_unimplemented.stderr b/tests/ui/diagnostic_namespace/on_unimplemented/feature-gate-diagnostic_on_unimplemented.stderr
deleted file mode 100644
index 719322fa0f55e..0000000000000
--- a/tests/ui/diagnostic_namespace/on_unimplemented/feature-gate-diagnostic_on_unimplemented.stderr
+++ /dev/null
@@ -1,13 +0,0 @@
-error[E0658]: `#[diagnostic]` attribute name space is experimental
-  --> $DIR/feature-gate-diagnostic_on_unimplemented.rs:1:3
-   |
-LL | #[diagnostic::on_unimplemented(message = "Foo")]
-   |   ^^^^^^^^^^
-   |
-   = note: see issue #111996 <https://github.com/rust-lang/rust/issues/111996> for more information
-   = help: add `#![feature(diagnostic_namespace)]` 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
-
-For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/diagnostic_namespace/on_unimplemented/ignore_unsupported_options_and_continue_to_use_fallback.rs b/tests/ui/diagnostic_namespace/on_unimplemented/ignore_unsupported_options_and_continue_to_use_fallback.rs
index 0893f29c4a3b4..5b25fb234bc52 100644
--- a/tests/ui/diagnostic_namespace/on_unimplemented/ignore_unsupported_options_and_continue_to_use_fallback.rs
+++ b/tests/ui/diagnostic_namespace/on_unimplemented/ignore_unsupported_options_and_continue_to_use_fallback.rs
@@ -1,5 +1,3 @@
-#![feature(diagnostic_namespace)]
-
 #[diagnostic::on_unimplemented(
     if(Self = "()"),
     //~^WARN malformed `on_unimplemented` attribute
diff --git a/tests/ui/diagnostic_namespace/on_unimplemented/ignore_unsupported_options_and_continue_to_use_fallback.stderr b/tests/ui/diagnostic_namespace/on_unimplemented/ignore_unsupported_options_and_continue_to_use_fallback.stderr
index e00846da77be5..56d125e20e5c4 100644
--- a/tests/ui/diagnostic_namespace/on_unimplemented/ignore_unsupported_options_and_continue_to_use_fallback.stderr
+++ b/tests/ui/diagnostic_namespace/on_unimplemented/ignore_unsupported_options_and_continue_to_use_fallback.stderr
@@ -1,5 +1,5 @@
 warning: malformed `on_unimplemented` attribute
-  --> $DIR/ignore_unsupported_options_and_continue_to_use_fallback.rs:4:5
+  --> $DIR/ignore_unsupported_options_and_continue_to_use_fallback.rs:2:5
    |
 LL |     if(Self = "()"),
    |     ^^^^^^^^^^^^^^^ invalid option found here
@@ -8,7 +8,7 @@ LL |     if(Self = "()"),
    = note: `#[warn(unknown_or_malformed_diagnostic_attributes)]` on by default
 
 warning: `message` is ignored due to previous definition of `message`
-  --> $DIR/ignore_unsupported_options_and_continue_to_use_fallback.rs:10:32
+  --> $DIR/ignore_unsupported_options_and_continue_to_use_fallback.rs:8:32
    |
 LL |     message = "custom message",
    |     -------------------------- `message` is first declared here
@@ -17,7 +17,7 @@ LL | #[diagnostic::on_unimplemented(message = "fallback!!")]
    |                                ^^^^^^^^^^^^^^^^^^^^^^ `message` is already declared here
 
 warning: malformed `on_unimplemented` attribute
-  --> $DIR/ignore_unsupported_options_and_continue_to_use_fallback.rs:4:5
+  --> $DIR/ignore_unsupported_options_and_continue_to_use_fallback.rs:2:5
    |
 LL |     if(Self = "()"),
    |     ^^^^^^^^^^^^^^^ invalid option found here
@@ -26,7 +26,7 @@ LL |     if(Self = "()"),
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 warning: `message` is ignored due to previous definition of `message`
-  --> $DIR/ignore_unsupported_options_and_continue_to_use_fallback.rs:10:32
+  --> $DIR/ignore_unsupported_options_and_continue_to_use_fallback.rs:8:32
    |
 LL |     message = "custom message",
    |     -------------------------- `message` is first declared here
@@ -37,7 +37,7 @@ LL | #[diagnostic::on_unimplemented(message = "fallback!!")]
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error[E0277]: custom message
-  --> $DIR/ignore_unsupported_options_and_continue_to_use_fallback.rs:20:15
+  --> $DIR/ignore_unsupported_options_and_continue_to_use_fallback.rs:18:15
    |
 LL |     takes_foo(());
    |     --------- ^^ fallback label
@@ -48,12 +48,12 @@ LL |     takes_foo(());
    = note: custom note
    = note: fallback note
 help: this trait has no implementations, consider adding one
-  --> $DIR/ignore_unsupported_options_and_continue_to_use_fallback.rs:15:1
+  --> $DIR/ignore_unsupported_options_and_continue_to_use_fallback.rs:13:1
    |
 LL | trait Foo {}
    | ^^^^^^^^^
 note: required by a bound in `takes_foo`
-  --> $DIR/ignore_unsupported_options_and_continue_to_use_fallback.rs:17:22
+  --> $DIR/ignore_unsupported_options_and_continue_to_use_fallback.rs:15:22
    |
 LL | fn takes_foo(_: impl Foo) {}
    |                      ^^^ required by this bound in `takes_foo`
diff --git a/tests/ui/diagnostic_namespace/on_unimplemented/multiple_notes.rs b/tests/ui/diagnostic_namespace/on_unimplemented/multiple_notes.rs
index 34cdb99c754b1..a5982f6492ca5 100644
--- a/tests/ui/diagnostic_namespace/on_unimplemented/multiple_notes.rs
+++ b/tests/ui/diagnostic_namespace/on_unimplemented/multiple_notes.rs
@@ -1,5 +1,3 @@
-#![feature(diagnostic_namespace)]
-
 #[diagnostic::on_unimplemented(message = "Foo", label = "Bar", note = "Baz", note = "Boom")]
 trait Foo {}
 
diff --git a/tests/ui/diagnostic_namespace/on_unimplemented/multiple_notes.stderr b/tests/ui/diagnostic_namespace/on_unimplemented/multiple_notes.stderr
index c72321d4617f0..93a0d0b3f4132 100644
--- a/tests/ui/diagnostic_namespace/on_unimplemented/multiple_notes.stderr
+++ b/tests/ui/diagnostic_namespace/on_unimplemented/multiple_notes.stderr
@@ -1,5 +1,5 @@
 error[E0277]: Foo
-  --> $DIR/multiple_notes.rs:14:15
+  --> $DIR/multiple_notes.rs:12:15
    |
 LL |     takes_foo(());
    |     --------- ^^ Bar
@@ -10,18 +10,18 @@ LL |     takes_foo(());
    = note: Baz
    = note: Boom
 help: this trait has no implementations, consider adding one
-  --> $DIR/multiple_notes.rs:4:1
+  --> $DIR/multiple_notes.rs:2:1
    |
 LL | trait Foo {}
    | ^^^^^^^^^
 note: required by a bound in `takes_foo`
-  --> $DIR/multiple_notes.rs:10:22
+  --> $DIR/multiple_notes.rs:8:22
    |
 LL | fn takes_foo(_: impl Foo) {}
    |                      ^^^ required by this bound in `takes_foo`
 
 error[E0277]: Bar
-  --> $DIR/multiple_notes.rs:16:15
+  --> $DIR/multiple_notes.rs:14:15
    |
 LL |     takes_bar(());
    |     --------- ^^ Foo
@@ -32,12 +32,12 @@ LL |     takes_bar(());
    = note: Baz
    = note: Baz2
 help: this trait has no implementations, consider adding one
-  --> $DIR/multiple_notes.rs:8:1
+  --> $DIR/multiple_notes.rs:6:1
    |
 LL | trait Bar {}
    | ^^^^^^^^^
 note: required by a bound in `takes_bar`
-  --> $DIR/multiple_notes.rs:11:22
+  --> $DIR/multiple_notes.rs:9:22
    |
 LL | fn takes_bar(_: impl Bar) {}
    |                      ^^^ required by this bound in `takes_bar`
diff --git a/tests/ui/diagnostic_namespace/on_unimplemented/on_unimplemented_simple.rs b/tests/ui/diagnostic_namespace/on_unimplemented/on_unimplemented_simple.rs
index 797edbc9ec564..7ca0312775964 100644
--- a/tests/ui/diagnostic_namespace/on_unimplemented/on_unimplemented_simple.rs
+++ b/tests/ui/diagnostic_namespace/on_unimplemented/on_unimplemented_simple.rs
@@ -1,5 +1,3 @@
-#![feature(diagnostic_namespace)]
-
 #[diagnostic::on_unimplemented(message = "Foo", label = "Bar", note = "Baz")]
 trait Foo {}
 
diff --git a/tests/ui/diagnostic_namespace/on_unimplemented/on_unimplemented_simple.stderr b/tests/ui/diagnostic_namespace/on_unimplemented/on_unimplemented_simple.stderr
index de57f7044bffe..6b17f40c6dd16 100644
--- a/tests/ui/diagnostic_namespace/on_unimplemented/on_unimplemented_simple.stderr
+++ b/tests/ui/diagnostic_namespace/on_unimplemented/on_unimplemented_simple.stderr
@@ -1,5 +1,5 @@
 error[E0277]: Foo
-  --> $DIR/on_unimplemented_simple.rs:9:15
+  --> $DIR/on_unimplemented_simple.rs:7:15
    |
 LL |     takes_foo(());
    |     --------- ^^ Bar
@@ -9,12 +9,12 @@ LL |     takes_foo(());
    = help: the trait `Foo` is not implemented for `()`
    = note: Baz
 help: this trait has no implementations, consider adding one
-  --> $DIR/on_unimplemented_simple.rs:4:1
+  --> $DIR/on_unimplemented_simple.rs:2:1
    |
 LL | trait Foo {}
    | ^^^^^^^^^
 note: required by a bound in `takes_foo`
-  --> $DIR/on_unimplemented_simple.rs:6:22
+  --> $DIR/on_unimplemented_simple.rs:4:22
    |
 LL | fn takes_foo(_: impl Foo) {}
    |                      ^^^ required by this bound in `takes_foo`
diff --git a/tests/ui/diagnostic_namespace/on_unimplemented/report_warning_on_duplicated_options.rs b/tests/ui/diagnostic_namespace/on_unimplemented/report_warning_on_duplicated_options.rs
index a7becd2f88f6d..8c0b81504177f 100644
--- a/tests/ui/diagnostic_namespace/on_unimplemented/report_warning_on_duplicated_options.rs
+++ b/tests/ui/diagnostic_namespace/on_unimplemented/report_warning_on_duplicated_options.rs
@@ -1,5 +1,3 @@
-#![feature(diagnostic_namespace)]
-
 #[diagnostic::on_unimplemented(
     message = "first message",
     label = "first label",
diff --git a/tests/ui/diagnostic_namespace/on_unimplemented/report_warning_on_duplicated_options.stderr b/tests/ui/diagnostic_namespace/on_unimplemented/report_warning_on_duplicated_options.stderr
index d30754dcf10d0..43ab6bf25a1a2 100644
--- a/tests/ui/diagnostic_namespace/on_unimplemented/report_warning_on_duplicated_options.stderr
+++ b/tests/ui/diagnostic_namespace/on_unimplemented/report_warning_on_duplicated_options.stderr
@@ -1,5 +1,5 @@
 warning: `message` is ignored due to previous definition of `message`
-  --> $DIR/report_warning_on_duplicated_options.rs:9:5
+  --> $DIR/report_warning_on_duplicated_options.rs:7:5
    |
 LL |     message = "first message",
    |     ------------------------- `message` is first declared here
@@ -10,7 +10,7 @@ LL |     message = "second message",
    = note: `#[warn(unknown_or_malformed_diagnostic_attributes)]` on by default
 
 warning: `label` is ignored due to previous definition of `label`
-  --> $DIR/report_warning_on_duplicated_options.rs:12:5
+  --> $DIR/report_warning_on_duplicated_options.rs:10:5
    |
 LL |     label = "first label",
    |     --------------------- `label` is first declared here
@@ -19,7 +19,7 @@ LL |     label = "second label",
    |     ^^^^^^^^^^^^^^^^^^^^^^ `label` is already declared here
 
 warning: `message` is ignored due to previous definition of `message`
-  --> $DIR/report_warning_on_duplicated_options.rs:9:5
+  --> $DIR/report_warning_on_duplicated_options.rs:7:5
    |
 LL |     message = "first message",
    |     ------------------------- `message` is first declared here
@@ -30,7 +30,7 @@ LL |     message = "second message",
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 warning: `label` is ignored due to previous definition of `label`
-  --> $DIR/report_warning_on_duplicated_options.rs:12:5
+  --> $DIR/report_warning_on_duplicated_options.rs:10:5
    |
 LL |     label = "first label",
    |     --------------------- `label` is first declared here
@@ -41,7 +41,7 @@ LL |     label = "second label",
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error[E0277]: first message
-  --> $DIR/report_warning_on_duplicated_options.rs:23:15
+  --> $DIR/report_warning_on_duplicated_options.rs:21:15
    |
 LL |     takes_foo(());
    |     --------- ^^ first label
@@ -52,12 +52,12 @@ LL |     takes_foo(());
    = note: custom note
    = note: second note
 help: this trait has no implementations, consider adding one
-  --> $DIR/report_warning_on_duplicated_options.rs:17:1
+  --> $DIR/report_warning_on_duplicated_options.rs:15:1
    |
 LL | trait Foo {}
    | ^^^^^^^^^
 note: required by a bound in `takes_foo`
-  --> $DIR/report_warning_on_duplicated_options.rs:20:22
+  --> $DIR/report_warning_on_duplicated_options.rs:18:22
    |
 LL | fn takes_foo(_: impl Foo) {}
    |                      ^^^ required by this bound in `takes_foo`
diff --git a/tests/ui/diagnostic_namespace/requires_path.rs b/tests/ui/diagnostic_namespace/requires_path.rs
index e8d6ca73ad0cf..4f3a1319cafff 100644
--- a/tests/ui/diagnostic_namespace/requires_path.rs
+++ b/tests/ui/diagnostic_namespace/requires_path.rs
@@ -1,5 +1,3 @@
-#![feature(diagnostic_namespace)]
-
 #[diagnostic]
 //~^ERROR cannot find attribute `diagnostic` in this scope
 pub struct Bar;
diff --git a/tests/ui/diagnostic_namespace/requires_path.stderr b/tests/ui/diagnostic_namespace/requires_path.stderr
index 5d07d3a22d50e..e02aacac8c1a7 100644
--- a/tests/ui/diagnostic_namespace/requires_path.stderr
+++ b/tests/ui/diagnostic_namespace/requires_path.stderr
@@ -1,5 +1,5 @@
 error: cannot find attribute `diagnostic` in this scope
-  --> $DIR/requires_path.rs:3:3
+  --> $DIR/requires_path.rs:1:3
    |
 LL | #[diagnostic]
    |   ^^^^^^^^^^
diff --git a/tests/ui/panics/default-backtrace-ice.stderr b/tests/ui/panics/default-backtrace-ice.stderr
index 9d27cb22ae942..82b61e43f4494 100644
--- a/tests/ui/panics/default-backtrace-ice.stderr
+++ b/tests/ui/panics/default-backtrace-ice.stderr
@@ -21,5 +21,5 @@ error: the compiler unexpectedly panicked. this is a bug.
 
 
 query stack during panic:
-#0 [resolver_for_lowering] getting the resolver for lowering
+#0 [resolver_for_lowering_raw] getting the resolver for lowering
 end of query stack
diff --git a/tests/ui/parser/impls-nested-within-anon-consts-semantic.rs b/tests/ui/parser/impls-nested-within-anon-consts-semantic.rs
new file mode 100644
index 0000000000000..36a7825cec8f1
--- /dev/null
+++ b/tests/ui/parser/impls-nested-within-anon-consts-semantic.rs
@@ -0,0 +1,35 @@
+// Regression test for issue #89342 and for part of #119924.
+//@ check-pass
+
+struct Expr<const N: u32>;
+
+trait Trait0 {
+    fn required(_: Expr<{
+        struct Type;
+
+        impl Type {
+            // This visibility qualifier used to get rejected.
+            pub fn perform() {}
+        }
+
+        0
+    }>);
+}
+
+trait Trait1 {}
+
+impl Trait1 for ()
+where
+    [(); {
+        struct Type;
+
+        impl Type {
+            // This visibility qualifier used to get rejected.
+            pub const STORE: Self = Self;
+        }
+
+        0
+    }]:
+{}
+
+fn main() {}
diff --git a/tests/ui/parser/impls-nested-within-fns-semantic-0.rs b/tests/ui/parser/impls-nested-within-fns-semantic-0.rs
new file mode 100644
index 0000000000000..107380d33c70a
--- /dev/null
+++ b/tests/ui/parser/impls-nested-within-fns-semantic-0.rs
@@ -0,0 +1,15 @@
+// Regression test for #121607 and for part of issue #119924.
+//@ check-pass
+
+trait Trait {
+    fn provided() {
+        pub struct Type;
+
+        impl Type {
+            // This visibility qualifier used to get rejected.
+            pub fn perform() {}
+        }
+    }
+}
+
+fn main() {}
diff --git a/tests/ui/parser/impls-nested-within-fns-semantic-1.rs b/tests/ui/parser/impls-nested-within-fns-semantic-1.rs
new file mode 100644
index 0000000000000..43530e41a66c1
--- /dev/null
+++ b/tests/ui/parser/impls-nested-within-fns-semantic-1.rs
@@ -0,0 +1,22 @@
+// Regression test for part of issue #119924.
+//@ check-pass
+
+#![feature(const_trait_impl, effects)]
+
+#[const_trait]
+trait Trait {
+    fn required();
+}
+
+impl const Trait for () {
+    fn required() {
+        pub struct Type;
+
+        impl Type {
+            // This visibility qualifier used to get rejected.
+            pub fn perform() {}
+        }
+    }
+}
+
+fn main() {}