Auto merge of #108386 - matthiaskrgr:rollup-nojivk9, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - #108063 (Ban associated type bounds in bad positions)
 - #108208 (Correctly handle aggregates in DataflowConstProp)
 - #108218 (Windows: Quote more batch file arguments)
 - #108349 (rustdoc: Prevent duplicated imports)
 - #108350 (Use associated type bounds in some places in the compiler)
 - #108358 (Add git config command to `.git-blame-ignore-revs`)
 - #108373 (hir-analysis: make where-clause-on-main diagnostic translatable)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

61 files changed, 455 insertions, 351 deletions

diff --git a/.git-blame-ignore-revs b/.git-blame-ignore-revs
index d20f19e60e8..353bfcb6ac1 100644
--- a/.git-blame-ignore-revs
+++ b/.git-blame-ignore-revs
@@ -1,3 +1,5 @@
+# Use `git config blame.ignorerevsfile .git-blame-ignore-revs` to make `git blame` ignore the following commits.
+
 # format the world
 a06baa56b95674fc626b3c3fd680d6a65357fe60
 # format libcore
diff --git a/compiler/rustc_ast_lowering/locales/en-US.ftl b/compiler/rustc_ast_lowering/locales/en-US.ftl
index 03c88c6c0eb..a2837deafde 100644
--- a/compiler/rustc_ast_lowering/locales/en-US.ftl
+++ b/compiler/rustc_ast_lowering/locales/en-US.ftl
@@ -19,6 +19,9 @@ ast_lowering_remove_parentheses = remove these parentheses
 ast_lowering_misplaced_impl_trait =
     `impl Trait` only allowed in function and inherent method return types, not in {$position}
 
+ast_lowering_misplaced_assoc_ty_binding =
+    associated type bounds are only allowed in where clauses and function signatures, not in {$position}
+
 ast_lowering_rustc_box_attribute_error =
     #[rustc_box] requires precisely one argument and no other attributes are allowed
 
diff --git a/compiler/rustc_ast_lowering/src/errors.rs b/compiler/rustc_ast_lowering/src/errors.rs
index 8b302ac2142..def74c2adee 100644
--- a/compiler/rustc_ast_lowering/src/errors.rs
+++ b/compiler/rustc_ast_lowering/src/errors.rs
@@ -79,6 +79,14 @@ pub struct MisplacedImplTrait<'a> {
     pub position: DiagnosticArgFromDisplay<'a>,
 }
 
+#[derive(Diagnostic)]
+#[diag(ast_lowering_misplaced_assoc_ty_binding)]
+pub struct MisplacedAssocTyBinding<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub position: DiagnosticArgFromDisplay<'a>,
+}
+
 #[derive(Diagnostic, Clone, Copy)]
 #[diag(ast_lowering_rustc_box_attribute_error)]
 pub struct RustcBoxAttributeError {
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index a726fbb72e9..c5b144e68dc 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -288,31 +288,31 @@ enum ImplTraitPosition {
 impl std::fmt::Display for ImplTraitPosition {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         let name = match self {
-            ImplTraitPosition::Path => "path",
-            ImplTraitPosition::Variable => "variable binding",
-            ImplTraitPosition::Trait => "trait",
-            ImplTraitPosition::AsyncBlock => "async block",
-            ImplTraitPosition::Bound => "bound",
-            ImplTraitPosition::Generic => "generic",
-            ImplTraitPosition::ExternFnParam => "`extern fn` param",
-            ImplTraitPosition::ClosureParam => "closure param",
-            ImplTraitPosition::PointerParam => "`fn` pointer param",
-            ImplTraitPosition::FnTraitParam => "`Fn` trait param",
-            ImplTraitPosition::TraitParam => "trait method param",
-            ImplTraitPosition::ImplParam => "`impl` method param",
-            ImplTraitPosition::ExternFnReturn => "`extern fn` return",
-            ImplTraitPosition::ClosureReturn => "closure return",
-            ImplTraitPosition::PointerReturn => "`fn` pointer return",
-            ImplTraitPosition::FnTraitReturn => "`Fn` trait return",
-            ImplTraitPosition::TraitReturn => "trait method return",
-            ImplTraitPosition::ImplReturn => "`impl` method return",
-            ImplTraitPosition::GenericDefault => "generic parameter default",
-            ImplTraitPosition::ConstTy => "const type",
-            ImplTraitPosition::StaticTy => "static type",
-            ImplTraitPosition::AssocTy => "associated type",
-            ImplTraitPosition::FieldTy => "field type",
-            ImplTraitPosition::Cast => "cast type",
-            ImplTraitPosition::ImplSelf => "impl header",
+            ImplTraitPosition::Path => "paths",
+            ImplTraitPosition::Variable => "variable bindings",
+            ImplTraitPosition::Trait => "traits",
+            ImplTraitPosition::AsyncBlock => "async blocks",
+            ImplTraitPosition::Bound => "bounds",
+            ImplTraitPosition::Generic => "generics",
+            ImplTraitPosition::ExternFnParam => "`extern fn` params",
+            ImplTraitPosition::ClosureParam => "closure params",
+            ImplTraitPosition::PointerParam => "`fn` pointer params",
+            ImplTraitPosition::FnTraitParam => "`Fn` trait params",
+            ImplTraitPosition::TraitParam => "trait method params",
+            ImplTraitPosition::ImplParam => "`impl` method params",
+            ImplTraitPosition::ExternFnReturn => "`extern fn` return types",
+            ImplTraitPosition::ClosureReturn => "closure return types",
+            ImplTraitPosition::PointerReturn => "`fn` pointer return types",
+            ImplTraitPosition::FnTraitReturn => "`Fn` trait return types",
+            ImplTraitPosition::TraitReturn => "trait method return types",
+            ImplTraitPosition::ImplReturn => "`impl` method return types",
+            ImplTraitPosition::GenericDefault => "generic parameter defaults",
+            ImplTraitPosition::ConstTy => "const types",
+            ImplTraitPosition::StaticTy => "static types",
+            ImplTraitPosition::AssocTy => "associated types",
+            ImplTraitPosition::FieldTy => "field types",
+            ImplTraitPosition::Cast => "cast types",
+            ImplTraitPosition::ImplSelf => "impl headers",
         };
 
         write!(f, "{name}")
@@ -1002,8 +1002,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         } else {
             self.arena.alloc(hir::GenericArgs::none())
         };
-        let itctx_tait = &ImplTraitContext::TypeAliasesOpaqueTy;
-
         let kind = match &constraint.kind {
             AssocConstraintKind::Equality { term } => {
                 let term = match term {
@@ -1013,8 +1011,14 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 hir::TypeBindingKind::Equality { term }
             }
             AssocConstraintKind::Bound { bounds } => {
+                enum DesugarKind<'a> {
+                    ImplTrait,
+                    Error(&'a ImplTraitPosition),
+                    Bound,
+                }
+
                 // Piggy-back on the `impl Trait` context to figure out the correct behavior.
-                let (desugar_to_impl_trait, itctx) = match itctx {
+                let desugar_kind = match itctx {
                     // We are in the return position:
                     //
                     //     fn foo() -> impl Iterator<Item: Debug>
@@ -1023,7 +1027,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     //
                     //     fn foo() -> impl Iterator<Item = impl Debug>
                     ImplTraitContext::ReturnPositionOpaqueTy { .. }
-                    | ImplTraitContext::TypeAliasesOpaqueTy { .. } => (true, itctx),
+                    | ImplTraitContext::TypeAliasesOpaqueTy { .. } => DesugarKind::ImplTrait,
 
                     // We are in the argument position, but within a dyn type:
                     //
@@ -1032,15 +1036,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     // so desugar to
                     //
                     //     fn foo(x: dyn Iterator<Item = impl Debug>)
-                    ImplTraitContext::Universal if self.is_in_dyn_type => (true, itctx),
+                    ImplTraitContext::Universal if self.is_in_dyn_type => DesugarKind::ImplTrait,
 
-                    // In `type Foo = dyn Iterator<Item: Debug>` we desugar to
-                    // `type Foo = dyn Iterator<Item = impl Debug>` but we have to override the
-                    // "impl trait context" to permit `impl Debug` in this position (it desugars
-                    // then to an opaque type).
-                    //
-                    // FIXME: this is only needed until `impl Trait` is allowed in type aliases.
-                    ImplTraitContext::Disallowed(_) if self.is_in_dyn_type => (true, itctx_tait),
+                    ImplTraitContext::Disallowed(position) if self.is_in_dyn_type => {
+                        DesugarKind::Error(position)
+                    }
 
                     // We are in the parameter position, but not within a dyn type:
                     //
@@ -1049,35 +1049,46 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     // so we leave it as is and this gets expanded in astconv to a bound like
                     // `<T as Iterator>::Item: Debug` where `T` is the type parameter for the
                     // `impl Iterator`.
-                    _ => (false, itctx),
+                    _ => DesugarKind::Bound,
                 };
 
-                if desugar_to_impl_trait {
-                    // Desugar `AssocTy: Bounds` into `AssocTy = impl Bounds`. We do this by
-                    // constructing the HIR for `impl bounds...` and then lowering that.
-
-                    let impl_trait_node_id = self.next_node_id();
-
-                    self.with_dyn_type_scope(false, |this| {
-                        let node_id = this.next_node_id();
-                        let ty = this.lower_ty(
-                            &Ty {
-                                id: node_id,
-                                kind: TyKind::ImplTrait(impl_trait_node_id, bounds.clone()),
-                                span: this.lower_span(constraint.span),
-                                tokens: None,
-                            },
-                            itctx,
-                        );
+                match desugar_kind {
+                    DesugarKind::ImplTrait => {
+                        // Desugar `AssocTy: Bounds` into `AssocTy = impl Bounds`. We do this by
+                        // constructing the HIR for `impl bounds...` and then lowering that.
 
-                        hir::TypeBindingKind::Equality { term: ty.into() }
-                    })
-                } else {
-                    // Desugar `AssocTy: Bounds` into a type binding where the
-                    // later desugars into a trait predicate.
-                    let bounds = self.lower_param_bounds(bounds, itctx);
+                        let impl_trait_node_id = self.next_node_id();
 
-                    hir::TypeBindingKind::Constraint { bounds }
+                        self.with_dyn_type_scope(false, |this| {
+                            let node_id = this.next_node_id();
+                            let ty = this.lower_ty(
+                                &Ty {
+                                    id: node_id,
+                                    kind: TyKind::ImplTrait(impl_trait_node_id, bounds.clone()),
+                                    span: this.lower_span(constraint.span),
+                                    tokens: None,
+                                },
+                                itctx,
+                            );
+
+                            hir::TypeBindingKind::Equality { term: ty.into() }
+                        })
+                    }
+                    DesugarKind::Bound => {
+                        // Desugar `AssocTy: Bounds` into a type binding where the
+                        // later desugars into a trait predicate.
+                        let bounds = self.lower_param_bounds(bounds, itctx);
+
+                        hir::TypeBindingKind::Constraint { bounds }
+                    }
+                    DesugarKind::Error(position) => {
+                        self.tcx.sess.emit_err(errors::MisplacedAssocTyBinding {
+                            span: constraint.span,
+                            position: DiagnosticArgFromDisplay(position),
+                        });
+                        let err_ty = &*self.arena.alloc(self.ty(constraint.span, hir::TyKind::Err));
+                        hir::TypeBindingKind::Equality { term: err_ty.into() }
+                    }
                 }
             }
         };
diff --git a/compiler/rustc_ast_passes/locales/en-US.ftl b/compiler/rustc_ast_passes/locales/en-US.ftl
index 5f28839f136..128e7255c61 100644
--- a/compiler/rustc_ast_passes/locales/en-US.ftl
+++ b/compiler/rustc_ast_passes/locales/en-US.ftl
@@ -11,9 +11,6 @@ ast_passes_forbidden_let_stable =
 ast_passes_deprecated_where_clause_location =
     where clause not allowed here
 
-ast_passes_forbidden_assoc_constraint =
-    associated type bounds are not allowed within structs, enums, or unions
-
 ast_passes_keyword_lifetime =
     lifetimes cannot use keyword names
 
diff --git a/compiler/rustc_ast_passes/src/ast_validation.rs b/compiler/rustc_ast_passes/src/ast_validation.rs
index 56977e45a1a..ee861e87355 100644
--- a/compiler/rustc_ast_passes/src/ast_validation.rs
+++ b/compiler/rustc_ast_passes/src/ast_validation.rs
@@ -71,10 +71,6 @@ struct AstValidator<'a> {
     /// or `Foo::Bar<impl Trait>`
     is_impl_trait_banned: bool,
 
-    /// Used to ban associated type bounds (i.e., `Type<AssocType: Bounds>`) in
-    /// certain positions.
-    is_assoc_ty_bound_banned: bool,
-
     /// See [ForbiddenLetReason]
     forbidden_let_reason: Option<ForbiddenLetReason>,
 
@@ -180,30 +176,12 @@ impl<'a> AstValidator<'a> {
         }
     }
 
-    fn with_banned_assoc_ty_bound(&mut self, f: impl FnOnce(&mut Self)) {
-        let old = mem::replace(&mut self.is_assoc_ty_bound_banned, true);
-        f(self);
-        self.is_assoc_ty_bound_banned = old;
-    }
-
     fn with_impl_trait(&mut self, outer: Option<Span>, f: impl FnOnce(&mut Self)) {
         let old = mem::replace(&mut self.outer_impl_trait, outer);
         f(self);
         self.outer_impl_trait = old;
     }
 
-    fn visit_assoc_constraint_from_generic_args(&mut self, constraint: &'a AssocConstraint) {
-        match constraint.kind {
-            AssocConstraintKind::Equality { .. } => {}
-            AssocConstraintKind::Bound { .. } => {
-                if self.is_assoc_ty_bound_banned {
-                    self.session.emit_err(ForbiddenAssocConstraint { span: constraint.span });
-                }
-            }
-        }
-        self.visit_assoc_constraint(constraint);
-    }
-
     // Mirrors `visit::walk_ty`, but tracks relevant state.
     fn walk_ty(&mut self, t: &'a Ty) {
         match &t.kind {
@@ -1248,7 +1226,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                         // are allowed to contain nested `impl Trait`.
                         AngleBracketedArg::Constraint(constraint) => {
                             self.with_impl_trait(None, |this| {
-                                this.visit_assoc_constraint_from_generic_args(constraint);
+                                this.visit_assoc_constraint(constraint);
                             });
                         }
                     }
@@ -1373,14 +1351,6 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
         visit::walk_param_bound(self, bound)
     }
 
-    fn visit_variant_data(&mut self, s: &'a VariantData) {
-        self.with_banned_assoc_ty_bound(|this| visit::walk_struct_def(this, s))
-    }
-
-    fn visit_enum_def(&mut self, enum_definition: &'a EnumDef) {
-        self.with_banned_assoc_ty_bound(|this| visit::walk_enum_def(this, enum_definition))
-    }
-
     fn visit_fn(&mut self, fk: FnKind<'a>, span: Span, id: NodeId) {
         // Only associated `fn`s can have `self` parameters.
         let self_semantic = match fk.ctxt() {
@@ -1709,7 +1679,6 @@ pub fn check_crate(session: &Session, krate: &Crate, lints: &mut LintBuffer) ->
         outer_impl_trait: None,
         disallow_tilde_const: None,
         is_impl_trait_banned: false,
-        is_assoc_ty_bound_banned: false,
         forbidden_let_reason: Some(ForbiddenLetReason::GenericForbidden),
         lint_buffer: lints,
     };
diff --git a/compiler/rustc_ast_passes/src/errors.rs b/compiler/rustc_ast_passes/src/errors.rs
index 69ce8daa455..f304f5a1956 100644
--- a/compiler/rustc_ast_passes/src/errors.rs
+++ b/compiler/rustc_ast_passes/src/errors.rs
@@ -24,13 +24,6 @@ pub struct ForbiddenLetStable {
 }
 
 #[derive(Diagnostic)]
-#[diag(ast_passes_forbidden_assoc_constraint)]
-pub struct ForbiddenAssocConstraint {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
 #[diag(ast_passes_keyword_lifetime)]
 pub struct KeywordLifetime {
     #[primary_span]
diff --git a/compiler/rustc_borrowck/src/lib.rs b/compiler/rustc_borrowck/src/lib.rs
index 42949143431..18d7bde60d7 100644
--- a/compiler/rustc_borrowck/src/lib.rs
+++ b/compiler/rustc_borrowck/src/lib.rs
@@ -1,6 +1,7 @@
 //! This query borrow-checks the MIR to (further) ensure it is not broken.
 
 #![allow(rustc::potential_query_instability)]
+#![feature(associated_type_bounds)]
 #![feature(box_patterns)]
 #![feature(let_chains)]
 #![feature(min_specialization)]
diff --git a/compiler/rustc_borrowck/src/type_check/canonical.rs b/compiler/rustc_borrowck/src/type_check/canonical.rs
index 1be20f18707..b27d5d20532 100644
--- a/compiler/rustc_borrowck/src/type_check/canonical.rs
+++ b/compiler/rustc_borrowck/src/type_check/canonical.rs
@@ -117,7 +117,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
 
     pub(super) fn prove_predicates(
         &mut self,
-        predicates: impl IntoIterator<Item = impl ToPredicate<'tcx> + std::fmt::Debug>,
+        predicates: impl IntoIterator<Item: ToPredicate<'tcx> + std::fmt::Debug>,
         locations: Locations,
         category: ConstraintCategory<'tcx>,
     ) {
diff --git a/compiler/rustc_hir_analysis/locales/en-US.ftl b/compiler/rustc_hir_analysis/locales/en-US.ftl
index aa56e60ec75..7e3a31f3355 100644
--- a/compiler/rustc_hir_analysis/locales/en-US.ftl
+++ b/compiler/rustc_hir_analysis/locales/en-US.ftl
@@ -127,5 +127,8 @@ hir_analysis_auto_deref_reached_recursion_limit = reached the recursion limit wh
     .label = deref recursion limit reached
     .help = consider increasing the recursion limit by adding a `#![recursion_limit = "{$suggested_limit}"]` attribute to your crate (`{$crate_name}`)
 
+hir_analysis_where_clause_on_main = `main` function is not allowed to have a `where` clause
+    .label = `main` cannot have a `where` clause
+
 hir_analysis_track_caller_on_main = `main` function is not allowed to be `#[track_caller]`
     .label = `main` function is not allowed to be `#[track_caller]`
diff --git a/compiler/rustc_hir_analysis/src/errors.rs b/compiler/rustc_hir_analysis/src/errors.rs
index be3ef03192c..d0fb7aff30e 100644
--- a/compiler/rustc_hir_analysis/src/errors.rs
+++ b/compiler/rustc_hir_analysis/src/errors.rs
@@ -317,6 +317,15 @@ pub struct AutoDerefReachedRecursionLimit<'a> {
 }
 
 #[derive(Diagnostic)]
+#[diag(hir_analysis_where_clause_on_main, code = "E0646")]
+pub(crate) struct WhereClauseOnMain {
+    #[primary_span]
+    pub span: Span,
+    #[label]
+    pub generics_span: Option<Span>,
+}
+
+#[derive(Diagnostic)]
 #[diag(hir_analysis_track_caller_on_main)]
 pub(crate) struct TrackCallerOnMain {
     #[primary_span]
diff --git a/compiler/rustc_hir_analysis/src/lib.rs b/compiler/rustc_hir_analysis/src/lib.rs
index d54e569905f..9a43ca685e3 100644
--- a/compiler/rustc_hir_analysis/src/lib.rs
+++ b/compiler/rustc_hir_analysis/src/lib.rs
@@ -271,16 +271,10 @@ fn check_main_fn_ty(tcx: TyCtxt<'_>, main_def_id: DefId) {
     } else if !main_fn_predicates.predicates.is_empty() {
         // generics may bring in implicit predicates, so we skip this check if generics is present.
         let generics_where_clauses_span = main_fn_where_clauses_span(tcx, main_def_id);
-        let mut diag = struct_span_err!(
-            tcx.sess,
-            generics_where_clauses_span.unwrap_or(main_span),
-            E0646,
-            "`main` function is not allowed to have a `where` clause"
-        );
-        if let Some(generics_where_clauses_span) = generics_where_clauses_span {
-            diag.span_label(generics_where_clauses_span, "`main` cannot have a `where` clause");
-        }
-        diag.emit();
+        tcx.sess.emit_err(errors::WhereClauseOnMain {
+            span: generics_where_clauses_span.unwrap_or(main_span),
+            generics_span: generics_where_clauses_span,
+        });
         error = true;
     }
 
diff --git a/compiler/rustc_infer/src/infer/combine.rs b/compiler/rustc_infer/src/infer/combine.rs
index 243545640f9..33292e871b1 100644
--- a/compiler/rustc_infer/src/infer/combine.rs
+++ b/compiler/rustc_infer/src/infer/combine.rs
@@ -478,10 +478,7 @@ impl<'infcx, 'tcx> CombineFields<'infcx, 'tcx> {
         self.obligations.extend(obligations.into_iter());
     }
 
-    pub fn register_predicates(
-        &mut self,
-        obligations: impl IntoIterator<Item = impl ToPredicate<'tcx>>,
-    ) {
+    pub fn register_predicates(&mut self, obligations: impl IntoIterator<Item: ToPredicate<'tcx>>) {
         self.obligations.extend(obligations.into_iter().map(|to_pred| {
             Obligation::new(self.infcx.tcx, self.trace.cause.clone(), self.param_env, to_pred)
         }))
@@ -814,10 +811,7 @@ pub trait ObligationEmittingRelation<'tcx>: TypeRelation<'tcx> {
     /// Register predicates that must hold in order for this relation to hold. Uses
     /// a default obligation cause, [`ObligationEmittingRelation::register_obligations`] should
     /// be used if control over the obligaton causes is required.
-    fn register_predicates(
-        &mut self,
-        obligations: impl IntoIterator<Item = impl ToPredicate<'tcx>>,
-    );
+    fn register_predicates(&mut self, obligations: impl IntoIterator<Item: ToPredicate<'tcx>>);
 
     /// Register an obligation that both constants must be equal to each other.
     ///
diff --git a/compiler/rustc_infer/src/infer/equate.rs b/compiler/rustc_infer/src/infer/equate.rs
index f830e9b3c53..54a62326ef7 100644
--- a/compiler/rustc_infer/src/infer/equate.rs
+++ b/compiler/rustc_infer/src/infer/equate.rs
@@ -201,10 +201,7 @@ impl<'tcx> TypeRelation<'tcx> for Equate<'_, '_, 'tcx> {
 }
 
 impl<'tcx> ObligationEmittingRelation<'tcx> for Equate<'_, '_, 'tcx> {
-    fn register_predicates(
-        &mut self,
-        obligations: impl IntoIterator<Item = impl ty::ToPredicate<'tcx>>,
-    ) {
+    fn register_predicates(&mut self, obligations: impl IntoIterator<Item: ty::ToPredicate<'tcx>>) {
         self.fields.register_predicates(obligations);
     }
 
diff --git a/compiler/rustc_infer/src/infer/glb.rs b/compiler/rustc_infer/src/infer/glb.rs
index 37ef022f827..49df393d83b 100644
--- a/compiler/rustc_infer/src/infer/glb.rs
+++ b/compiler/rustc_infer/src/infer/glb.rs
@@ -148,10 +148,7 @@ impl<'combine, 'infcx, 'tcx> LatticeDir<'infcx, 'tcx> for Glb<'combine, 'infcx,
 }
 
 impl<'tcx> ObligationEmittingRelation<'tcx> for Glb<'_, '_, 'tcx> {
-    fn register_predicates(
-        &mut self,
-        obligations: impl IntoIterator<Item = impl ty::ToPredicate<'tcx>>,
-    ) {
+    fn register_predicates(&mut self, obligations: impl IntoIterator<Item: ty::ToPredicate<'tcx>>) {
         self.fields.register_predicates(obligations);
     }
 
diff --git a/compiler/rustc_infer/src/infer/lub.rs b/compiler/rustc_infer/src/infer/lub.rs
index f541fcbceed..c871ccb21f8 100644
--- a/compiler/rustc_infer/src/infer/lub.rs
+++ b/compiler/rustc_infer/src/infer/lub.rs
@@ -148,10 +148,7 @@ impl<'combine, 'infcx, 'tcx> LatticeDir<'infcx, 'tcx> for Lub<'combine, 'infcx,
 }
 
 impl<'tcx> ObligationEmittingRelation<'tcx> for Lub<'_, '_, 'tcx> {
-    fn register_predicates(
-        &mut self,
-        obligations: impl IntoIterator<Item = impl ty::ToPredicate<'tcx>>,
-    ) {
+    fn register_predicates(&mut self, obligations: impl IntoIterator<Item: ty::ToPredicate<'tcx>>) {
         self.fields.register_predicates(obligations);
     }
 
diff --git a/compiler/rustc_infer/src/infer/nll_relate/mod.rs b/compiler/rustc_infer/src/infer/nll_relate/mod.rs
index 214a5850fb6..6e413a7f412 100644
--- a/compiler/rustc_infer/src/infer/nll_relate/mod.rs
+++ b/compiler/rustc_infer/src/infer/nll_relate/mod.rs
@@ -763,10 +763,7 @@ impl<'tcx, D> ObligationEmittingRelation<'tcx> for TypeRelating<'_, 'tcx, D>
 where
     D: TypeRelatingDelegate<'tcx>,
 {
-    fn register_predicates(
-        &mut self,
-        obligations: impl IntoIterator<Item = impl ty::ToPredicate<'tcx>>,
-    ) {
+    fn register_predicates(&mut self, obligations: impl IntoIterator<Item: ty::ToPredicate<'tcx>>) {
         self.delegate.register_obligations(
             obligations
                 .into_iter()
diff --git a/compiler/rustc_infer/src/infer/sub.rs b/compiler/rustc_infer/src/infer/sub.rs
index b4e647dcc9b..4c003789a4e 100644
--- a/compiler/rustc_infer/src/infer/sub.rs
+++ b/compiler/rustc_infer/src/infer/sub.rs
@@ -228,10 +228,7 @@ impl<'tcx> TypeRelation<'tcx> for Sub<'_, '_, 'tcx> {
 }
 
 impl<'tcx> ObligationEmittingRelation<'tcx> for Sub<'_, '_, 'tcx> {
-    fn register_predicates(
-        &mut self,
-        obligations: impl IntoIterator<Item = impl ty::ToPredicate<'tcx>>,
-    ) {
+    fn register_predicates(&mut self, obligations: impl IntoIterator<Item: ty::ToPredicate<'tcx>>) {
         self.fields.register_predicates(obligations);
     }
 
diff --git a/compiler/rustc_infer/src/lib.rs b/compiler/rustc_infer/src/lib.rs
index b03ecb59750..bdc313c2141 100644
--- a/compiler/rustc_infer/src/lib.rs
+++ b/compiler/rustc_infer/src/lib.rs
@@ -13,6 +13,7 @@
 //! This API is completely unstable and subject to change.
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
+#![feature(associated_type_bounds)]
 #![feature(box_patterns)]
 #![feature(control_flow_enum)]
 #![feature(extend_one)]
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index f347604a2cd..6bf54fa5417 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -1856,7 +1856,7 @@ impl<'tcx> TyCtxt<'tcx> {
     pub fn mk_fn_def(
         self,
         def_id: DefId,
-        substs: impl IntoIterator<Item = impl Into<GenericArg<'tcx>>>,
+        substs: impl IntoIterator<Item: Into<GenericArg<'tcx>>>,
     ) -> Ty<'tcx> {
         let substs = self.check_substs(def_id, substs);
         self.mk_ty(FnDef(def_id, substs))
@@ -1866,7 +1866,7 @@ impl<'tcx> TyCtxt<'tcx> {
     fn check_substs(
         self,
         _def_id: DefId,
-        substs: impl IntoIterator<Item = impl Into<GenericArg<'tcx>>>,
+        substs: impl IntoIterator<Item: Into<GenericArg<'tcx>>>,
     ) -> SubstsRef<'tcx> {
         let substs = substs.into_iter().map(Into::into);
         #[cfg(debug_assertions)]
@@ -1901,7 +1901,7 @@ impl<'tcx> TyCtxt<'tcx> {
     pub fn mk_projection(
         self,
         item_def_id: DefId,
-        substs: impl IntoIterator<Item = impl Into<GenericArg<'tcx>>>,
+        substs: impl IntoIterator<Item: Into<GenericArg<'tcx>>>,
     ) -> Ty<'tcx> {
         self.mk_alias(ty::Projection, self.mk_alias_ty(item_def_id, substs))
     }
@@ -2293,7 +2293,7 @@ impl<'tcx> TyCtxt<'tcx> {
     pub fn mk_trait_ref(
         self,
         trait_def_id: DefId,
-        substs: impl IntoIterator<Item = impl Into<GenericArg<'tcx>>>,
+        substs: impl IntoIterator<Item: Into<GenericArg<'tcx>>>,
     ) -> ty::TraitRef<'tcx> {
         let substs = self.check_substs(trait_def_id, substs);
         ty::TraitRef { def_id: trait_def_id, substs, _use_mk_trait_ref_instead: () }
@@ -2302,7 +2302,7 @@ impl<'tcx> TyCtxt<'tcx> {
     pub fn mk_alias_ty(
         self,
         def_id: DefId,
-        substs: impl IntoIterator<Item = impl Into<GenericArg<'tcx>>>,
+        substs: impl IntoIterator<Item: Into<GenericArg<'tcx>>>,
     ) -> ty::AliasTy<'tcx> {
         let substs = self.check_substs(def_id, substs);
         ty::AliasTy { def_id, substs, _use_mk_alias_ty_instead: () }
@@ -2472,7 +2472,7 @@ impl<'tcx> TyCtxtAt<'tcx> {
     pub fn mk_trait_ref(
         self,
         trait_lang_item: LangItem,
-        substs: impl IntoIterator<Item = impl Into<ty::GenericArg<'tcx>>>,
+        substs: impl IntoIterator<Item: Into<ty::GenericArg<'tcx>>>,
     ) -> ty::TraitRef<'tcx> {
         let trait_def_id = self.require_lang_item(trait_lang_item, Some(self.span));
         self.tcx.mk_trait_ref(trait_def_id, substs)
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index 7563656f91b..658f09a850d 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -568,7 +568,7 @@ impl<'tcx> GeneratorSubsts<'tcx> {
         self,
         def_id: DefId,
         tcx: TyCtxt<'tcx>,
-    ) -> impl Iterator<Item = impl Iterator<Item = Ty<'tcx>> + Captures<'tcx>> {
+    ) -> impl Iterator<Item: Iterator<Item = Ty<'tcx>> + Captures<'tcx>> {
         let layout = tcx.generator_layout(def_id).unwrap();
         layout.variant_fields.iter().map(move |variant| {
             variant.iter().map(move |field| {
diff --git a/compiler/rustc_mir_build/src/build/matches/test.rs b/compiler/rustc_mir_build/src/build/matches/test.rs
index 8859f5002e4..2de89f67dfd 100644
--- a/compiler/rustc_mir_build/src/build/matches/test.rs
+++ b/compiler/rustc_mir_build/src/build/matches/test.rs
@@ -832,7 +832,7 @@ fn trait_method<'tcx>(
     tcx: TyCtxt<'tcx>,
     trait_def_id: DefId,
     method_name: Symbol,
-    substs: impl IntoIterator<Item = impl Into<GenericArg<'tcx>>>,
+    substs: impl IntoIterator<Item: Into<GenericArg<'tcx>>>,
 ) -> ConstantKind<'tcx> {
     // The unhygienic comparison here is acceptable because this is only
     // used on known traits.
diff --git a/compiler/rustc_mir_transform/src/dataflow_const_prop.rs b/compiler/rustc_mir_transform/src/dataflow_const_prop.rs
index 19019e3ef74..49ded10ba1f 100644
--- a/compiler/rustc_mir_transform/src/dataflow_const_prop.rs
+++ b/compiler/rustc_mir_transform/src/dataflow_const_prop.rs
@@ -122,7 +122,10 @@ impl<'tcx> ValueAnalysis<'tcx> for ConstAnalysis<'_, 'tcx> {
     ) {
         match rvalue {
             Rvalue::Aggregate(kind, operands) => {
-                state.flood_with(target.as_ref(), self.map(), FlatSet::Bottom);
+                // If we assign `target = Enum::Variant#0(operand)`,
+                // we must make sure that all `target as Variant#i` are `Top`.
+                state.flood(target.as_ref(), self.map());
+
                 if let Some(target_idx) = self.map().find(target.as_ref()) {
                     let (variant_target, variant_index) = match **kind {
                         AggregateKind::Tuple | AggregateKind::Closure(..) => {
@@ -131,18 +134,21 @@ impl<'tcx> ValueAnalysis<'tcx> for ConstAnalysis<'_, 'tcx> {
                         AggregateKind::Adt(def_id, variant_index, ..) => {
                             match self.tcx.def_kind(def_id) {
                                 DefKind::Struct => (Some(target_idx), None),
-                                DefKind::Enum => (Some(target_idx), Some(variant_index)),
+                                DefKind::Enum => (
+                                    self.map.apply(target_idx, TrackElem::Variant(variant_index)),
+                                    Some(variant_index),
+                                ),
                                 _ => (None, None),
                             }
                         }
                         _ => (None, None),
                     };
-                    if let Some(target) = variant_target {
+                    if let Some(variant_target_idx) = variant_target {
                         for (field_index, operand) in operands.iter().enumerate() {
-                            if let Some(field) = self
-                                .map()
-                                .apply(target, TrackElem::Field(Field::from_usize(field_index)))
-                            {
+                            if let Some(field) = self.map().apply(
+                                variant_target_idx,
+                                TrackElem::Field(Field::from_usize(field_index)),
+                            ) {
                                 let result = self.handle_operand(operand, state);
                                 state.insert_idx(field, result, self.map());
                             }
@@ -151,6 +157,11 @@ impl<'tcx> ValueAnalysis<'tcx> for ConstAnalysis<'_, 'tcx> {
                     if let Some(variant_index) = variant_index
                         && let Some(discr_idx) = self.map().apply(target_idx, TrackElem::Discriminant)
                     {
+                        // We are assigning the discriminant as part of an aggregate.
+                        // This discriminant can only alias a variant field's value if the operand
+                        // had an invalid value for that type.
+                        // Using invalid values is UB, so we are allowed to perform the assignment
+                        // without extra flooding.
                         let enum_ty = target.ty(self.local_decls, self.tcx).ty;
                         if let Some(discr_val) = self.eval_discriminant(enum_ty, variant_index) {
                             state.insert_value_idx(discr_idx, FlatSet::Elem(discr_val), &self.map);
diff --git a/compiler/rustc_trait_selection/src/infer.rs b/compiler/rustc_trait_selection/src/infer.rs
index 015029b7ac4..9b47c7299bb 100644
--- a/compiler/rustc_trait_selection/src/infer.rs
+++ b/compiler/rustc_trait_selection/src/infer.rs
@@ -42,7 +42,7 @@ pub trait InferCtxtExt<'tcx> {
     fn type_implements_trait(
         &self,
         trait_def_id: DefId,
-        params: impl IntoIterator<Item = impl Into<GenericArg<'tcx>>>,
+        params: impl IntoIterator<Item: Into<GenericArg<'tcx>>>,
         param_env: ty::ParamEnv<'tcx>,
     ) -> traits::EvaluationResult;
 }
@@ -82,7 +82,7 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
     fn type_implements_trait(
         &self,
         trait_def_id: DefId,
-        params: impl IntoIterator<Item = impl Into<GenericArg<'tcx>>>,
+        params: impl IntoIterator<Item: Into<GenericArg<'tcx>>>,
         param_env: ty::ParamEnv<'tcx>,
     ) -> traits::EvaluationResult {
         let trait_ref = self.tcx.mk_trait_ref(trait_def_id, params);
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/method_chain.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/method_chain.rs
index 9474c70cb53..1174efdbfa8 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/method_chain.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/method_chain.rs
@@ -98,7 +98,7 @@ impl<'tcx> ObligationEmittingRelation<'tcx> for CollectAllMismatches<'_, 'tcx> {
 
     fn register_predicates(
         &mut self,
-        _obligations: impl IntoIterator<Item = impl ty::ToPredicate<'tcx>>,
+        _obligations: impl IntoIterator<Item: ty::ToPredicate<'tcx>>,
     ) {
         // FIXME(deferred_projection_equality)
     }
diff --git a/compiler/rustc_trait_selection/src/traits/util.rs b/compiler/rustc_trait_selection/src/traits/util.rs
index 0c55c35ffb4..638a6592c08 100644
--- a/compiler/rustc_trait_selection/src/traits/util.rs
+++ b/compiler/rustc_trait_selection/src/traits/util.rs
@@ -239,7 +239,7 @@ pub fn predicate_for_trait_def<'tcx>(
     cause: ObligationCause<'tcx>,
     trait_def_id: DefId,
     recursion_depth: usize,
-    params: impl IntoIterator<Item = impl Into<GenericArg<'tcx>>>,
+    params: impl IntoIterator<Item: Into<GenericArg<'tcx>>>,
 ) -> PredicateObligation<'tcx> {
     let trait_ref = tcx.mk_trait_ref(trait_def_id, params);
     predicate_for_trait_ref(tcx, cause, param_env, trait_ref, recursion_depth)
diff --git a/library/std/src/sys/windows/args.rs b/library/std/src/sys/windows/args.rs
index 6741ae46d32..30356fa8519 100644
--- a/library/std/src/sys/windows/args.rs
+++ b/library/std/src/sys/windows/args.rs
@@ -270,7 +270,7 @@ pub(crate) fn make_bat_command_line(
     // It is necessary to surround the command in an extra pair of quotes,
     // hence the trailing quote here. It will be closed after all arguments
     // have been added.
-    let mut cmd: Vec<u16> = "cmd.exe /c \"".encode_utf16().collect();
+    let mut cmd: Vec<u16> = "cmd.exe /d /c \"".encode_utf16().collect();
 
     // Push the script name surrounded by its quote pair.
     cmd.push(b'"' as u16);
@@ -290,6 +290,15 @@ pub(crate) fn make_bat_command_line(
     // reconstructed by the batch script by default.
     for arg in args {
         cmd.push(' ' as u16);
+        // Make sure to always quote special command prompt characters, including:
+        // * Characters `cmd /?` says require quotes.
+        // * `%` for environment variables, as in `%TMP%`.
+        // * `|<>` pipe/redirect characters.
+        const SPECIAL: &[u8] = b"\t &()[]{}^=;!'+,`~%|<>";
+        let force_quotes = match arg {
+            Arg::Regular(arg) if !force_quotes => arg.bytes().iter().any(|c| SPECIAL.contains(c)),
+            _ => force_quotes,
+        };
         append_arg(&mut cmd, arg, force_quotes)?;
     }
 
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 58223f322b2..648423e1289 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -77,7 +77,7 @@ pub(crate) fn clean_doc_module<'tcx>(doc: &DocModule<'tcx>, cx: &mut DocContext<
     // This covers the case where somebody does an import which should pull in an item,
     // but there's already an item with the same namespace and same name. Rust gives
     // priority to the not-imported one, so we should, too.
-    items.extend(doc.items.iter().flat_map(|(item, renamed, import_id)| {
+    items.extend(doc.items.values().flat_map(|(item, renamed, import_id)| {
         // First, lower everything other than imports.
         if matches!(item.kind, hir::ItemKind::Use(_, hir::UseKind::Glob)) {
             return Vec::new();
@@ -90,7 +90,7 @@ pub(crate) fn clean_doc_module<'tcx>(doc: &DocModule<'tcx>, cx: &mut DocContext<
         }
         v
     }));
-    items.extend(doc.items.iter().flat_map(|(item, renamed, _)| {
+    items.extend(doc.items.values().flat_map(|(item, renamed, _)| {
         // Now we actually lower the imports, skipping everything else.
         if let hir::ItemKind::Use(path, hir::UseKind::Glob) = item.kind {
             let name = renamed.unwrap_or_else(|| cx.tcx.hir().name(item.hir_id()));
diff --git a/src/librustdoc/visit_ast.rs b/src/librustdoc/visit_ast.rs
index 9c1e5f4a3cd..277201e4de9 100644
--- a/src/librustdoc/visit_ast.rs
+++ b/src/librustdoc/visit_ast.rs
@@ -1,7 +1,7 @@
 //! The Rust AST Visitor. Extracts useful information and massages it into a form
 //! usable for `clean`.
 
-use rustc_data_structures::fx::FxHashSet;
+use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{DefId, DefIdMap, LocalDefId, LocalDefIdSet};
@@ -26,8 +26,12 @@ pub(crate) struct Module<'hir> {
     pub(crate) where_inner: Span,
     pub(crate) mods: Vec<Module<'hir>>,
     pub(crate) def_id: LocalDefId,
-    // (item, renamed, import_id)
-    pub(crate) items: Vec<(&'hir hir::Item<'hir>, Option<Symbol>, Option<LocalDefId>)>,
+    /// The key is the item `ItemId` and the value is: (item, renamed, import_id).
+    /// We use `FxIndexMap` to keep the insert order.
+    pub(crate) items: FxIndexMap<
+        (LocalDefId, Option<Symbol>),
+        (&'hir hir::Item<'hir>, Option<Symbol>, Option<LocalDefId>),
+    >,
     pub(crate) foreigns: Vec<(&'hir hir::ForeignItem<'hir>, Option<Symbol>)>,
 }
 
@@ -38,7 +42,7 @@ impl Module<'_> {
             def_id,
             where_inner,
             mods: Vec::new(),
-            items: Vec::new(),
+            items: FxIndexMap::default(),
             foreigns: Vec::new(),
         }
     }
@@ -136,7 +140,7 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
                 inserted.insert(def_id)
             {
                     let item = self.cx.tcx.hir().expect_item(local_def_id);
-                    top_level_module.items.push((item, None, None));
+                    top_level_module.items.insert((local_def_id, Some(item.ident.name)), (item, None, None));
             }
         }
 
@@ -294,7 +298,11 @@ impl<'a, 'tcx> RustdocVisitor<'a, 'tcx> {
         renamed: Option<Symbol>,
         parent_id: Option<LocalDefId>,
     ) {
-        self.modules.last_mut().unwrap().items.push((item, renamed, parent_id))
+        self.modules
+            .last_mut()
+            .unwrap()
+            .items
+            .insert((item.owner_id.def_id, renamed), (item, renamed, parent_id));
     }
 
     fn visit_item_inner(
diff --git a/src/tools/jsondoclint/src/validator.rs b/src/tools/jsondoclint/src/validator.rs
index c6f55410e44..a1f675a3b40 100644
--- a/src/tools/jsondoclint/src/validator.rs
+++ b/src/tools/jsondoclint/src/validator.rs
@@ -71,6 +71,19 @@ impl<'a> Validator<'a> {
         }
     }
 
+    fn check_items(&mut self, id: &Id, items: &[Id]) {
+        let mut visited_ids = HashSet::with_capacity(items.len());
+
+        for item in items {
+            if !visited_ids.insert(item) {
+                self.fail(
+                    id,
+                    ErrorKind::Custom(format!("Duplicated entry in `items` field: `{item:?}`")),
+                );
+            }
+        }
+    }
+
     fn check_item(&mut self, id: &'a Id) {
         if let Some(item) = &self.krate.index.get(id) {
             item.links.values().for_each(|id| self.add_any_id(id));
@@ -83,9 +96,9 @@ impl<'a> Validator<'a> {
                 ItemEnum::Enum(x) => self.check_enum(x),
                 ItemEnum::Variant(x) => self.check_variant(x, id),
                 ItemEnum::Function(x) => self.check_function(x),
-                ItemEnum::Trait(x) => self.check_trait(x),
+                ItemEnum::Trait(x) => self.check_trait(x, id),
                 ItemEnum::TraitAlias(x) => self.check_trait_alias(x),
-                ItemEnum::Impl(x) => self.check_impl(x),
+                ItemEnum::Impl(x) => self.check_impl(x, id),
                 ItemEnum::Typedef(x) => self.check_typedef(x),
                 ItemEnum::OpaqueTy(x) => self.check_opaque_ty(x),
                 ItemEnum::Constant(x) => self.check_constant(x),
@@ -94,7 +107,7 @@ impl<'a> Validator<'a> {
                 ItemEnum::Macro(x) => self.check_macro(x),
                 ItemEnum::ProcMacro(x) => self.check_proc_macro(x),
                 ItemEnum::Primitive(x) => self.check_primitive_type(x),
-                ItemEnum::Module(x) => self.check_module(x),
+                ItemEnum::Module(x) => self.check_module(x, id),
                 // FIXME: Why don't these have their own structs?
                 ItemEnum::ExternCrate { .. } => {}
                 ItemEnum::AssocConst { type_, default: _ } => self.check_type(type_),
@@ -112,7 +125,8 @@ impl<'a> Validator<'a> {
     }
 
     // Core checkers
-    fn check_module(&mut self, module: &'a Module) {
+    fn check_module(&mut self, module: &'a Module, id: &Id) {
+        self.check_items(id, &module.items);
         module.items.iter().for_each(|i| self.add_mod_item_id(i));
     }
 
@@ -181,7 +195,8 @@ impl<'a> Validator<'a> {
         self.check_fn_decl(&x.decl);
     }
 
-    fn check_trait(&mut self, x: &'a Trait) {
+    fn check_trait(&mut self, x: &'a Trait, id: &Id) {
+        self.check_items(id, &x.items);
         self.check_generics(&x.generics);
         x.items.iter().for_each(|i| self.add_trait_item_id(i));
         x.bounds.iter().for_each(|i| self.check_generic_bound(i));
@@ -193,7 +208,8 @@ impl<'a> Validator<'a> {
         x.params.iter().for_each(|i| self.check_generic_bound(i));
     }
 
-    fn check_impl(&mut self, x: &'a Impl) {
+    fn check_impl(&mut self, x: &'a Impl, id: &Id) {
+        self.check_items(id, &x.items);
         self.check_generics(&x.generics);
         if let Some(path) = &x.trait_ {
             self.check_path(path, PathKind::Trait);
diff --git a/tests/mir-opt/dataflow-const-prop/enum.multiple.DataflowConstProp.diff b/tests/mir-opt/dataflow-const-prop/enum.multiple.DataflowConstProp.diff
new file mode 100644
index 00000000000..c4002d65e5d
--- /dev/null
+++ b/tests/mir-opt/dataflow-const-prop/enum.multiple.DataflowConstProp.diff
@@ -0,0 +1,82 @@
+- // MIR for `multiple` before DataflowConstProp
++ // MIR for `multiple` after DataflowConstProp
+  
+  fn multiple(_1: bool, _2: u8) -> () {
+      debug x => _1;                       // in scope 0 at $DIR/enum.rs:+0:13: +0:14
+      debug i => _2;                       // in scope 0 at $DIR/enum.rs:+0:22: +0:23
+      let mut _0: ();                      // return place in scope 0 at $DIR/enum.rs:+0:29: +0:29
+      let _3: std::option::Option<u8>;     // in scope 0 at $DIR/enum.rs:+1:9: +1:10
+      let mut _4: bool;                    // in scope 0 at $DIR/enum.rs:+1:16: +1:17
+      let mut _5: u8;                      // in scope 0 at $DIR/enum.rs:+2:14: +2:15
+      let mut _7: isize;                   // in scope 0 at $DIR/enum.rs:+9:23: +9:30
+      scope 1 {
+          debug e => _3;                   // in scope 1 at $DIR/enum.rs:+1:9: +1:10
+          let _6: u8;                      // in scope 1 at $DIR/enum.rs:+9:9: +9:10
+          let _8: u8;                      // in scope 1 at $DIR/enum.rs:+9:28: +9:29
+          scope 2 {
+              debug x => _6;               // in scope 2 at $DIR/enum.rs:+9:9: +9:10
+              let _9: u8;                  // in scope 2 at $DIR/enum.rs:+11:9: +11:10
+              scope 4 {
+                  debug y => _9;           // in scope 4 at $DIR/enum.rs:+11:9: +11:10
+              }
+          }
+          scope 3 {
+              debug i => _8;               // in scope 3 at $DIR/enum.rs:+9:28: +9:29
+          }
+      }
+  
+      bb0: {
+          StorageLive(_3);                 // scope 0 at $DIR/enum.rs:+1:9: +1:10
+          StorageLive(_4);                 // scope 0 at $DIR/enum.rs:+1:16: +1:17
+          _4 = _1;                         // scope 0 at $DIR/enum.rs:+1:16: +1:17
+          switchInt(move _4) -> [0: bb2, otherwise: bb1]; // scope 0 at $DIR/enum.rs:+1:16: +1:17
+      }
+  
+      bb1: {
+          StorageLive(_5);                 // scope 0 at $DIR/enum.rs:+2:14: +2:15
+          _5 = _2;                         // scope 0 at $DIR/enum.rs:+2:14: +2:15
+          _3 = Option::<u8>::Some(move _5); // scope 0 at $DIR/enum.rs:+2:9: +2:16
+          StorageDead(_5);                 // scope 0 at $DIR/enum.rs:+2:15: +2:16
+          goto -> bb3;                     // scope 0 at $DIR/enum.rs:+1:13: +5:6
+      }
+  
+      bb2: {
+          _3 = Option::<u8>::None;         // scope 0 at $DIR/enum.rs:+4:9: +4:13
+          goto -> bb3;                     // scope 0 at $DIR/enum.rs:+1:13: +5:6
+      }
+  
+      bb3: {
+          StorageDead(_4);                 // scope 0 at $DIR/enum.rs:+5:5: +5:6
+          StorageLive(_6);                 // scope 1 at $DIR/enum.rs:+9:9: +9:10
+          _7 = discriminant(_3);           // scope 1 at $DIR/enum.rs:+9:19: +9:20
+          switchInt(move _7) -> [0: bb4, 1: bb6, otherwise: bb5]; // scope 1 at $DIR/enum.rs:+9:13: +9:20
+      }
+  
+      bb4: {
+          _6 = const 0_u8;                 // scope 1 at $DIR/enum.rs:+9:45: +9:46
+          goto -> bb7;                     // scope 1 at $DIR/enum.rs:+9:45: +9:46
+      }
+  
+      bb5: {
+          unreachable;                     // scope 1 at $DIR/enum.rs:+9:19: +9:20
+      }
+  
+      bb6: {
+          StorageLive(_8);                 // scope 1 at $DIR/enum.rs:+9:28: +9:29
+          _8 = ((_3 as Some).0: u8);       // scope 1 at $DIR/enum.rs:+9:28: +9:29
+          _6 = _8;                         // scope 3 at $DIR/enum.rs:+9:34: +9:35
+          StorageDead(_8);                 // scope 1 at $DIR/enum.rs:+9:34: +9:35
+          goto -> bb7;                     // scope 1 at $DIR/enum.rs:+9:34: +9:35
+      }
+  
+      bb7: {
+          StorageLive(_9);                 // scope 2 at $DIR/enum.rs:+11:9: +11:10
+          _9 = _6;                         // scope 2 at $DIR/enum.rs:+11:13: +11:14
+          _0 = const ();                   // scope 0 at $DIR/enum.rs:+0:29: +12:2
+          StorageDead(_9);                 // scope 2 at $DIR/enum.rs:+12:1: +12:2
+          StorageDead(_6);                 // scope 1 at $DIR/enum.rs:+12:1: +12:2
+          StorageDead(_3);                 // scope 0 at $DIR/enum.rs:+12:1: +12:2
+          return;                          // scope 0 at $DIR/enum.rs:+12:2: +12:2
+      }
+  }
+  
diff --git a/tests/mir-opt/dataflow-const-prop/enum.rs b/tests/mir-opt/dataflow-const-prop/enum.rs
index 7ea405bd9c4..79a20d7ef45 100644
--- a/tests/mir-opt/dataflow-const-prop/enum.rs
+++ b/tests/mir-opt/dataflow-const-prop/enum.rs
@@ -46,7 +46,23 @@ fn mutate_discriminant() -> u8 {
     )
 }
 
+// EMIT_MIR enum.multiple.DataflowConstProp.diff
+fn multiple(x: bool, i: u8) {
+    let e = if x {
+        Some(i)
+    } else {
+        None
+    };
+    // The dataflow state must have:
+    //   discriminant(e) => Top
+    //   (e as Some).0 => Top
+    let x = match e { Some(i) => i, None => 0 };
+    // Therefore, `x` should be `Top` here, and no replacement shall happen.
+    let y = x;
+}
+
 fn main() {
     simple();
     mutate_discriminant();
+    multiple(false, 5);
 }
diff --git a/tests/mir-opt/dataflow-const-prop/enum.simple.DataflowConstProp.diff b/tests/mir-opt/dataflow-const-prop/enum.simple.DataflowConstProp.diff
index 1fb65e65845..22bdc35d694 100644
--- a/tests/mir-opt/dataflow-const-prop/enum.simple.DataflowConstProp.diff
+++ b/tests/mir-opt/dataflow-const-prop/enum.simple.DataflowConstProp.diff
@@ -45,8 +45,10 @@
   
       bb3: {
           StorageLive(_4);                 // scope 1 at $DIR/enum.rs:+2:29: +2:30
-          _4 = ((_1 as V1).0: i32);        // scope 1 at $DIR/enum.rs:+2:29: +2:30
-          _2 = _4;                         // scope 3 at $DIR/enum.rs:+2:35: +2:36
+-         _4 = ((_1 as V1).0: i32);        // scope 1 at $DIR/enum.rs:+2:29: +2:30
+-         _2 = _4;                         // scope 3 at $DIR/enum.rs:+2:35: +2:36
++         _4 = const 0_i32;                // scope 1 at $DIR/enum.rs:+2:29: +2:30
++         _2 = const 0_i32;                // scope 3 at $DIR/enum.rs:+2:35: +2:36
           StorageDead(_4);                 // scope 1 at $DIR/enum.rs:+2:35: +2:36
           goto -> bb4;                     // scope 1 at $DIR/enum.rs:+2:35: +2:36
       }
diff --git a/tests/rustdoc/reexports-of-same-name.rs b/tests/rustdoc/reexports-of-same-name.rs
new file mode 100644
index 00000000000..fe6f1b38ca6
--- /dev/null
+++ b/tests/rustdoc/reexports-of-same-name.rs
@@ -0,0 +1,26 @@
+// This test ensures that there are 4 imports as expected:
+// * 2 for `Foo`
+// * 2 for `Bar`
+
+#![crate_name = "foo"]
+
+// @has 'foo/index.html'
+
+pub mod nested {
+    /// Foo the struct
+    pub struct Foo {}
+
+    #[allow(non_snake_case)]
+    /// Foo the function
+    pub fn Foo() {}
+}
+
+// @count - '//*[@id="main-content"]//code' 'pub use nested::Foo;' 2
+// @has - '//*[@id="reexport.Foo"]//a[@href="nested/struct.Foo.html"]' 'Foo'
+// @has - '//*[@id="reexport.Foo-1"]//a[@href="nested/fn.Foo.html"]' 'Foo'
+pub use nested::Foo;
+
+// @count - '//*[@id="main-content"]//code' 'pub use Foo as Bar;' 2
+// @has - '//*[@id="reexport.Bar"]//a[@href="nested/struct.Foo.html"]' 'Foo'
+// @has - '//*[@id="reexport.Bar-1"]//a[@href="nested/fn.Foo.html"]' 'Foo'
+pub use Foo as Bar;
diff --git a/tests/ui/associated-consts/issue-105330.stderr b/tests/ui/associated-consts/issue-105330.stderr
index 08570d4a5d9..bbafc55dac3 100644
--- a/tests/ui/associated-consts/issue-105330.stderr
+++ b/tests/ui/associated-consts/issue-105330.stderr
@@ -33,7 +33,7 @@ LL | fn main<A: TraitWAssocConst<A=32>>() {
    = note: see issue #92827 <https://github.com/rust-lang/rust/issues/92827> for more information
    = help: add `#![feature(associated_const_equality)]` to the crate attributes to enable
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in impl header
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in impl headers
   --> $DIR/issue-105330.rs:6:27
    |
 LL | impl TraitWAssocConst for impl Demo {
diff --git a/tests/ui/associated-type-bounds/bad-universal-in-dyn-in-where-clause.rs b/tests/ui/associated-type-bounds/bad-universal-in-dyn-in-where-clause.rs
new file mode 100644
index 00000000000..8cab1f66c27
--- /dev/null
+++ b/tests/ui/associated-type-bounds/bad-universal-in-dyn-in-where-clause.rs
@@ -0,0 +1,14 @@
+#![feature(associated_type_bounds)]
+
+trait B {
+    type AssocType;
+}
+
+fn f()
+where
+    dyn for<'j> B<AssocType: 'j>:,
+    //~^ ERROR associated type bounds are only allowed in where clauses and function signatures
+{
+}
+
+fn main() {}
diff --git a/tests/ui/associated-type-bounds/bad-universal-in-dyn-in-where-clause.stderr b/tests/ui/associated-type-bounds/bad-universal-in-dyn-in-where-clause.stderr
new file mode 100644
index 00000000000..6fa266d23d4
--- /dev/null
+++ b/tests/ui/associated-type-bounds/bad-universal-in-dyn-in-where-clause.stderr
@@ -0,0 +1,8 @@
+error: associated type bounds are only allowed in where clauses and function signatures, not in bounds
+  --> $DIR/bad-universal-in-dyn-in-where-clause.rs:9:19
+   |
+LL |     dyn for<'j> B<AssocType: 'j>:,
+   |                   ^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/tests/ui/associated-type-bounds/bad-universal-in-impl-sig.rs b/tests/ui/associated-type-bounds/bad-universal-in-impl-sig.rs
new file mode 100644
index 00000000000..1d5d181efcc
--- /dev/null
+++ b/tests/ui/associated-type-bounds/bad-universal-in-impl-sig.rs
@@ -0,0 +1,13 @@
+#![feature(associated_type_bounds)]
+
+trait Trait {
+    type Item;
+}
+
+trait Trait2 {}
+
+// It's not possible to insert a universal `impl Trait` here!
+impl dyn Trait<Item: Trait2> {}
+//~^ ERROR associated type bounds are only allowed in where clauses and function signatures
+
+fn main() {}
diff --git a/tests/ui/associated-type-bounds/bad-universal-in-impl-sig.stderr b/tests/ui/associated-type-bounds/bad-universal-in-impl-sig.stderr
new file mode 100644
index 00000000000..8b66627d57f
--- /dev/null
+++ b/tests/ui/associated-type-bounds/bad-universal-in-impl-sig.stderr
@@ -0,0 +1,8 @@
+error: associated type bounds are only allowed in where clauses and function signatures, not in impl headers
+  --> $DIR/bad-universal-in-impl-sig.rs:10:16
+   |
+LL | impl dyn Trait<Item: Trait2> {}
+   |                ^^^^^^^^^^^^
+
+error: aborting due to previous error
+
diff --git a/tests/ui/associated-type-bounds/inside-adt.rs b/tests/ui/associated-type-bounds/inside-adt.rs
index 8eb8c44bb42..057966941dc 100644
--- a/tests/ui/associated-type-bounds/inside-adt.rs
+++ b/tests/ui/associated-type-bounds/inside-adt.rs
@@ -3,28 +3,24 @@
 use std::mem::ManuallyDrop;
 
 struct S1 { f: dyn Iterator<Item: Copy> }
-//~^ ERROR associated type bounds are not allowed within structs, enums, or unions
+//~^ ERROR associated type bounds are only allowed in where clauses and function signatures
 struct S2 { f: Box<dyn Iterator<Item: Copy>> }
-//~^ ERROR associated type bounds are not allowed within structs, enums, or unions
+//~^ ERROR associated type bounds are only allowed in where clauses and function signatures
 struct S3 { f: dyn Iterator<Item: 'static> }
-//~^ ERROR associated type bounds are not allowed within structs, enums, or unions
+//~^ ERROR associated type bounds are only allowed in where clauses and function signatures
 
 enum E1 { V(dyn Iterator<Item: Copy>) }
-//~^ ERROR associated type bounds are not allowed within structs, enums, or unions
-//~| ERROR the size for values of type `(dyn Iterator<Item = impl Copy> + 'static)`
+//~^ ERROR associated type bounds are only allowed in where clauses and function signatures
 enum E2 { V(Box<dyn Iterator<Item: Copy>>) }
-//~^ ERROR associated type bounds are not allowed within structs, enums, or unions
+//~^ ERROR associated type bounds are only allowed in where clauses and function signatures
 enum E3 { V(dyn Iterator<Item: 'static>) }
-//~^ ERROR associated type bounds are not allowed within structs, enums, or unions
-//~| ERROR the size for values of type `(dyn Iterator<Item = impl Sized + 'static> + 'static)`
+//~^ ERROR associated type bounds are only allowed in where clauses and function signatures
 
 union U1 { f: ManuallyDrop<dyn Iterator<Item: Copy>> }
-//~^ ERROR associated type bounds are not allowed within structs, enums, or unions
-//~| ERROR the size for values of type `(dyn Iterator<Item = impl Copy> + 'static)`
+//~^ ERROR associated type bounds are only allowed in where clauses and function signatures
 union U2 { f: ManuallyDrop<Box<dyn Iterator<Item: Copy>>> }
-//~^ ERROR associated type bounds are not allowed within structs, enums, or unions
+//~^ ERROR associated type bounds are only allowed in where clauses and function signatures
 union U3 { f: ManuallyDrop<dyn Iterator<Item: 'static>> }
-//~^ ERROR associated type bounds are not allowed within structs, enums, or unions
-//~| ERROR the size for values of type `(dyn Iterator<Item = impl Sized + 'static> + 'static)`
+//~^ ERROR associated type bounds are only allowed in where clauses and function signatures
 
 fn main() {}
diff --git a/tests/ui/associated-type-bounds/inside-adt.stderr b/tests/ui/associated-type-bounds/inside-adt.stderr
index 1668b613b25..f848bd798ee 100644
--- a/tests/ui/associated-type-bounds/inside-adt.stderr
+++ b/tests/ui/associated-type-bounds/inside-adt.stderr
@@ -1,131 +1,56 @@
-error: associated type bounds are not allowed within structs, enums, or unions
+error: associated type bounds are only allowed in where clauses and function signatures, not in field types
   --> $DIR/inside-adt.rs:5:29
    |
 LL | struct S1 { f: dyn Iterator<Item: Copy> }
    |                             ^^^^^^^^^^
 
-error: associated type bounds are not allowed within structs, enums, or unions
+error: associated type bounds are only allowed in where clauses and function signatures, not in field types
   --> $DIR/inside-adt.rs:7:33
    |
 LL | struct S2 { f: Box<dyn Iterator<Item: Copy>> }
    |                                 ^^^^^^^^^^
 
-error: associated type bounds are not allowed within structs, enums, or unions
+error: associated type bounds are only allowed in where clauses and function signatures, not in field types
   --> $DIR/inside-adt.rs:9:29
    |
 LL | struct S3 { f: dyn Iterator<Item: 'static> }
    |                             ^^^^^^^^^^^^^
 
-error: associated type bounds are not allowed within structs, enums, or unions
+error: associated type bounds are only allowed in where clauses and function signatures, not in field types
   --> $DIR/inside-adt.rs:12:26
    |
 LL | enum E1 { V(dyn Iterator<Item: Copy>) }
    |                          ^^^^^^^^^^
 
-error: associated type bounds are not allowed within structs, enums, or unions
-  --> $DIR/inside-adt.rs:15:30
+error: associated type bounds are only allowed in where clauses and function signatures, not in field types
+  --> $DIR/inside-adt.rs:14:30
    |
 LL | enum E2 { V(Box<dyn Iterator<Item: Copy>>) }
    |                              ^^^^^^^^^^
 
-error: associated type bounds are not allowed within structs, enums, or unions
-  --> $DIR/inside-adt.rs:17:26
+error: associated type bounds are only allowed in where clauses and function signatures, not in field types
+  --> $DIR/inside-adt.rs:16:26
    |
 LL | enum E3 { V(dyn Iterator<Item: 'static>) }
    |                          ^^^^^^^^^^^^^
 
-error: associated type bounds are not allowed within structs, enums, or unions
-  --> $DIR/inside-adt.rs:21:41
+error: associated type bounds are only allowed in where clauses and function signatures, not in field types
+  --> $DIR/inside-adt.rs:19:41
    |
 LL | union U1 { f: ManuallyDrop<dyn Iterator<Item: Copy>> }
    |                                         ^^^^^^^^^^
 
-error: associated type bounds are not allowed within structs, enums, or unions
-  --> $DIR/inside-adt.rs:24:45
+error: associated type bounds are only allowed in where clauses and function signatures, not in field types
+  --> $DIR/inside-adt.rs:21:45
    |
 LL | union U2 { f: ManuallyDrop<Box<dyn Iterator<Item: Copy>>> }
    |                                             ^^^^^^^^^^
 
-error: associated type bounds are not allowed within structs, enums, or unions
-  --> $DIR/inside-adt.rs:26:41
+error: associated type bounds are only allowed in where clauses and function signatures, not in field types
+  --> $DIR/inside-adt.rs:23:41
    |
 LL | union U3 { f: ManuallyDrop<dyn Iterator<Item: 'static>> }
    |                                         ^^^^^^^^^^^^^
 
-error[E0277]: the size for values of type `(dyn Iterator<Item = impl Copy> + 'static)` cannot be known at compilation time
-  --> $DIR/inside-adt.rs:12:13
-   |
-LL | enum E1 { V(dyn Iterator<Item: Copy>) }
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
-   |
-   = help: the trait `Sized` is not implemented for `(dyn Iterator<Item = impl Copy> + 'static)`
-   = note: no field of an enum variant may have a dynamically sized type
-   = help: change the field's type to have a statically known size
-help: borrowed types always have a statically known size
-   |
-LL | enum E1 { V(&dyn Iterator<Item: Copy>) }
-   |             +
-help: the `Box` type always has a statically known size and allocates its contents in the heap
-   |
-LL | enum E1 { V(Box<dyn Iterator<Item: Copy>>) }
-   |             ++++                        +
-
-error[E0277]: the size for values of type `(dyn Iterator<Item = impl Sized + 'static> + 'static)` cannot be known at compilation time
-  --> $DIR/inside-adt.rs:17:13
-   |
-LL | enum E3 { V(dyn Iterator<Item: 'static>) }
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
-   |
-   = help: the trait `Sized` is not implemented for `(dyn Iterator<Item = impl Sized + 'static> + 'static)`
-   = note: no field of an enum variant may have a dynamically sized type
-   = help: change the field's type to have a statically known size
-help: borrowed types always have a statically known size
-   |
-LL | enum E3 { V(&dyn Iterator<Item: 'static>) }
-   |             +
-help: the `Box` type always has a statically known size and allocates its contents in the heap
-   |
-LL | enum E3 { V(Box<dyn Iterator<Item: 'static>>) }
-   |             ++++                           +
-
-error[E0277]: the size for values of type `(dyn Iterator<Item = impl Copy> + 'static)` cannot be known at compilation time
-  --> $DIR/inside-adt.rs:21:15
-   |
-LL | union U1 { f: ManuallyDrop<dyn Iterator<Item: Copy>> }
-   |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
-   |
-   = help: within `ManuallyDrop<(dyn Iterator<Item = impl Copy> + 'static)>`, the trait `Sized` is not implemented for `(dyn Iterator<Item = impl Copy> + 'static)`
-   = note: required because it appears within the type `ManuallyDrop<dyn Iterator<Item = impl Copy>>`
-   = note: no field of a union may have a dynamically sized type
-   = help: change the field's type to have a statically known size
-help: borrowed types always have a statically known size
-   |
-LL | union U1 { f: &ManuallyDrop<dyn Iterator<Item: Copy>> }
-   |               +
-help: the `Box` type always has a statically known size and allocates its contents in the heap
-   |
-LL | union U1 { f: Box<ManuallyDrop<dyn Iterator<Item: Copy>>> }
-   |               ++++                                      +
-
-error[E0277]: the size for values of type `(dyn Iterator<Item = impl Sized + 'static> + 'static)` cannot be known at compilation time
-  --> $DIR/inside-adt.rs:26:15
-   |
-LL | union U3 { f: ManuallyDrop<dyn Iterator<Item: 'static>> }
-   |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
-   |
-   = help: within `ManuallyDrop<(dyn Iterator<Item = impl Sized + 'static> + 'static)>`, the trait `Sized` is not implemented for `(dyn Iterator<Item = impl Sized + 'static> + 'static)`
-   = note: required because it appears within the type `ManuallyDrop<dyn Iterator<Item = impl Sized>>`
-   = note: no field of a union may have a dynamically sized type
-   = help: change the field's type to have a statically known size
-help: borrowed types always have a statically known size
-   |
-LL | union U3 { f: &ManuallyDrop<dyn Iterator<Item: 'static>> }
-   |               +
-help: the `Box` type always has a statically known size and allocates its contents in the heap
-   |
-LL | union U3 { f: Box<ManuallyDrop<dyn Iterator<Item: 'static>>> }
-   |               ++++                                         +
-
-error: aborting due to 13 previous errors
+error: aborting due to 9 previous errors
 
-For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/async-await/in-trait/fn-not-async-err2.rs b/tests/ui/async-await/in-trait/fn-not-async-err2.rs
index 2c4ed553580..78017429f73 100644
--- a/tests/ui/async-await/in-trait/fn-not-async-err2.rs
+++ b/tests/ui/async-await/in-trait/fn-not-async-err2.rs
@@ -11,7 +11,7 @@ trait MyTrait {
 
 impl MyTrait for i32 {
     fn foo(&self) -> impl Future<Output = i32> {
-        //~^ ERROR `impl Trait` only allowed in function and inherent method return types, not in `impl` method return [E0562]
+        //~^ ERROR `impl Trait` only allowed in function and inherent method return types, not in `impl` method return types
         async { *self }
     }
 }
diff --git a/tests/ui/async-await/in-trait/fn-not-async-err2.stderr b/tests/ui/async-await/in-trait/fn-not-async-err2.stderr
index f591f184772..37d9669c012 100644
--- a/tests/ui/async-await/in-trait/fn-not-async-err2.stderr
+++ b/tests/ui/async-await/in-trait/fn-not-async-err2.stderr
@@ -1,4 +1,4 @@
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `impl` method return
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `impl` method return types
   --> $DIR/fn-not-async-err2.rs:13:22
    |
 LL |     fn foo(&self) -> impl Future<Output = i32> {
diff --git a/tests/ui/feature-gates/feature-gate-associated_type_bounds.stderr b/tests/ui/feature-gates/feature-gate-associated_type_bounds.stderr
index edbbf7db565..4233a8af9b6 100644
--- a/tests/ui/feature-gates/feature-gate-associated_type_bounds.stderr
+++ b/tests/ui/feature-gates/feature-gate-associated_type_bounds.stderr
@@ -115,19 +115,19 @@ LL |     let _: impl Tr1<As1: Copy> = S1;
    = note: see issue #52662 <https://github.com/rust-lang/rust/issues/52662> for more information
    = help: add `#![feature(associated_type_bounds)]` to the crate attributes to enable
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in const type
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in const types
   --> $DIR/feature-gate-associated_type_bounds.rs:55:14
    |
 LL | const _cdef: impl Tr1<As1: Copy> = S1;
    |              ^^^^^^^^^^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in const type
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in const types
   --> $DIR/feature-gate-associated_type_bounds.rs:61:15
    |
 LL | static _sdef: impl Tr1<As1: Copy> = S1;
    |               ^^^^^^^^^^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable binding
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable bindings
   --> $DIR/feature-gate-associated_type_bounds.rs:68:12
    |
 LL |     let _: impl Tr1<As1: Copy> = S1;
diff --git a/tests/ui/feature-gates/feature-gate-impl_trait_in_fn_trait_return.stderr b/tests/ui/feature-gates/feature-gate-impl_trait_in_fn_trait_return.stderr
index 760dcb615c8..c8c3e13d7fc 100644
--- a/tests/ui/feature-gates/feature-gate-impl_trait_in_fn_trait_return.stderr
+++ b/tests/ui/feature-gates/feature-gate-impl_trait_in_fn_trait_return.stderr
@@ -1,4 +1,4 @@
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait return
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait return types
   --> $DIR/feature-gate-impl_trait_in_fn_trait_return.rs:1:24
    |
 LL | fn f() -> impl Fn() -> impl Sized { || () }
@@ -7,7 +7,7 @@ LL | fn f() -> impl Fn() -> impl Sized { || () }
    = note: see issue #99697 <https://github.com/rust-lang/rust/issues/99697> for more information
    = help: add `#![feature(impl_trait_in_fn_trait_return)]` to the crate attributes to enable
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait return
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait return types
   --> $DIR/feature-gate-impl_trait_in_fn_trait_return.rs:3:32
    |
 LL | fn g() -> &'static dyn Fn() -> impl Sized { &|| () }
diff --git a/tests/ui/feature-gates/feature-gate-return_position_impl_trait_in_trait.stderr b/tests/ui/feature-gates/feature-gate-return_position_impl_trait_in_trait.stderr
index aeabed4a6ab..0082b6fafee 100644
--- a/tests/ui/feature-gates/feature-gate-return_position_impl_trait_in_trait.stderr
+++ b/tests/ui/feature-gates/feature-gate-return_position_impl_trait_in_trait.stderr
@@ -1,4 +1,4 @@
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in trait method return
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in trait method return types
   --> $DIR/feature-gate-return_position_impl_trait_in_trait.rs:8:17
    |
 LL |     fn bar() -> impl Sized;
@@ -7,7 +7,7 @@ LL |     fn bar() -> impl Sized;
    = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
    = help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in trait method return
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in trait method return types
   --> $DIR/feature-gate-return_position_impl_trait_in_trait.rs:9:21
    |
 LL |     fn baz() -> Box<impl std::fmt::Display>;
@@ -16,7 +16,7 @@ LL |     fn baz() -> Box<impl std::fmt::Display>;
    = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
    = help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in trait method return
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in trait method return types
   --> $DIR/feature-gate-return_position_impl_trait_in_trait.rs:15:23
    |
 LL |     async fn bar() -> impl Sized;
diff --git a/tests/ui/impl-trait/issues/issue-54600.stderr b/tests/ui/impl-trait/issues/issue-54600.stderr
index 316566a57a8..7ef063af952 100644
--- a/tests/ui/impl-trait/issues/issue-54600.stderr
+++ b/tests/ui/impl-trait/issues/issue-54600.stderr
@@ -1,4 +1,4 @@
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable binding
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable bindings
   --> $DIR/issue-54600.rs:4:19
    |
 LL |     let x: Option<impl Debug> = Some(44_u32);
diff --git a/tests/ui/impl-trait/issues/issue-54840.stderr b/tests/ui/impl-trait/issues/issue-54840.stderr
index 8d82133ac90..1d1316f0e11 100644
--- a/tests/ui/impl-trait/issues/issue-54840.stderr
+++ b/tests/ui/impl-trait/issues/issue-54840.stderr
@@ -1,4 +1,4 @@
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable binding
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable bindings
   --> $DIR/issue-54840.rs:5:13
    |
 LL |     let j: &impl Add = &i;
diff --git a/tests/ui/impl-trait/issues/issue-58504.stderr b/tests/ui/impl-trait/issues/issue-58504.stderr
index 6656e9fc3fb..26ec2a4f9cf 100644
--- a/tests/ui/impl-trait/issues/issue-58504.stderr
+++ b/tests/ui/impl-trait/issues/issue-58504.stderr
@@ -1,4 +1,4 @@
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable binding
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable bindings
   --> $DIR/issue-58504.rs:10:16
    |
 LL |     let gens: [impl Generator<Return=!, Yield=()>;2] = [ mk_gen(), mk_gen() ];
diff --git a/tests/ui/impl-trait/issues/issue-58956.stderr b/tests/ui/impl-trait/issues/issue-58956.stderr
index f591c07bcf5..2b4d0abdffc 100644
--- a/tests/ui/impl-trait/issues/issue-58956.stderr
+++ b/tests/ui/impl-trait/issues/issue-58956.stderr
@@ -1,10 +1,10 @@
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in const type
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in const types
   --> $DIR/issue-58956.rs:7:11
    |
 LL | const _A: impl Lam = {
    |           ^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable binding
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable bindings
   --> $DIR/issue-58956.rs:9:17
    |
 LL |     let x: Wrap<impl Lam> = Wrap(B);
diff --git a/tests/ui/impl-trait/issues/issue-70971.stderr b/tests/ui/impl-trait/issues/issue-70971.stderr
index 4dda4c22aa2..d066256bfb0 100644
--- a/tests/ui/impl-trait/issues/issue-70971.stderr
+++ b/tests/ui/impl-trait/issues/issue-70971.stderr
@@ -1,4 +1,4 @@
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable binding
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable bindings
   --> $DIR/issue-70971.rs:2:14
    |
 LL |     let x : (impl Copy,) = (true,);
diff --git a/tests/ui/impl-trait/issues/issue-79099.stderr b/tests/ui/impl-trait/issues/issue-79099.stderr
index 362c67dafd2..580250a62fe 100644
--- a/tests/ui/impl-trait/issues/issue-79099.stderr
+++ b/tests/ui/impl-trait/issues/issue-79099.stderr
@@ -9,7 +9,7 @@ LL |         let f: impl core::future::Future<Output = u8> = async { 1 };
    = help: pass `--edition 2021` to `rustc`
    = note: for more on editions, read https://doc.rust-lang.org/edition-guide
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable binding
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable bindings
   --> $DIR/issue-79099.rs:3:16
    |
 LL |         let f: impl core::future::Future<Output = u8> = async { 1 };
diff --git a/tests/ui/impl-trait/issues/issue-83929-impl-trait-in-generic-default.stderr b/tests/ui/impl-trait/issues/issue-83929-impl-trait-in-generic-default.stderr
index a227f0ba7d1..656bd047061 100644
--- a/tests/ui/impl-trait/issues/issue-83929-impl-trait-in-generic-default.stderr
+++ b/tests/ui/impl-trait/issues/issue-83929-impl-trait-in-generic-default.stderr
@@ -1,10 +1,10 @@
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generic parameter default
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generic parameter defaults
   --> $DIR/issue-83929-impl-trait-in-generic-default.rs:1:16
    |
 LL | struct Foo<T = impl Copy>(T);
    |                ^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generic parameter default
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generic parameter defaults
   --> $DIR/issue-83929-impl-trait-in-generic-default.rs:4:20
    |
 LL | type Result<T, E = impl std::error::Error> = std::result::Result<T, E>;
diff --git a/tests/ui/impl-trait/issues/issue-84919.stderr b/tests/ui/impl-trait/issues/issue-84919.stderr
index 5abe1bd8779..36010fdef36 100644
--- a/tests/ui/impl-trait/issues/issue-84919.stderr
+++ b/tests/ui/impl-trait/issues/issue-84919.stderr
@@ -1,4 +1,4 @@
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable binding
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable bindings
   --> $DIR/issue-84919.rs:5:13
    |
 LL |     let _x: impl Trait = ();
diff --git a/tests/ui/impl-trait/issues/issue-86642.stderr b/tests/ui/impl-trait/issues/issue-86642.stderr
index a137777840b..b6f8a54f35a 100644
--- a/tests/ui/impl-trait/issues/issue-86642.stderr
+++ b/tests/ui/impl-trait/issues/issue-86642.stderr
@@ -1,4 +1,4 @@
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in const type
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in const types
   --> $DIR/issue-86642.rs:1:11
    |
 LL | static x: impl Fn(&str) -> Result<&str, ()> = move |source| {
diff --git a/tests/ui/impl-trait/issues/issue-87295.stderr b/tests/ui/impl-trait/issues/issue-87295.stderr
index 0b043056b84..ec59b719c10 100644
--- a/tests/ui/impl-trait/issues/issue-87295.stderr
+++ b/tests/ui/impl-trait/issues/issue-87295.stderr
@@ -1,4 +1,4 @@
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable binding
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable bindings
   --> $DIR/issue-87295.rs:16:31
    |
 LL |     let _do_not_waste: Struct<impl Trait<Output = i32>> = Struct::new(());
diff --git a/tests/ui/impl-trait/nested_impl_trait.stderr b/tests/ui/impl-trait/nested_impl_trait.stderr
index 9a8f5a34068..ffe84b8e86f 100644
--- a/tests/ui/impl-trait/nested_impl_trait.stderr
+++ b/tests/ui/impl-trait/nested_impl_trait.stderr
@@ -34,7 +34,7 @@ LL |     fn bad(x: impl Into<u32>) -> impl Into<impl Debug> { x }
    |                                  |         nested `impl Trait` here
    |                                  outer `impl Trait`
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `fn` pointer return
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `fn` pointer return types
   --> $DIR/nested_impl_trait.rs:10:32
    |
 LL | fn bad_in_fn_syntax(x: fn() -> impl Into<impl Debug>) {}
diff --git a/tests/ui/impl-trait/where-allowed.stderr b/tests/ui/impl-trait/where-allowed.stderr
index 201aba3adff..1cae3f77cc5 100644
--- a/tests/ui/impl-trait/where-allowed.stderr
+++ b/tests/ui/impl-trait/where-allowed.stderr
@@ -43,109 +43,109 @@ LL | type InReturnInTypeAlias<R> = fn() -> impl Debug;
    = note: see issue #63063 <https://github.com/rust-lang/rust/issues/63063> for more information
    = help: add `#![feature(type_alias_impl_trait)]` to the crate attributes to enable
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `fn` pointer param
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `fn` pointer params
   --> $DIR/where-allowed.rs:16:40
    |
 LL | fn in_fn_parameter_in_parameters(_: fn(impl Debug)) { panic!() }
    |                                        ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `fn` pointer return
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `fn` pointer return types
   --> $DIR/where-allowed.rs:20:42
    |
 LL | fn in_fn_return_in_parameters(_: fn() -> impl Debug) { panic!() }
    |                                          ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `fn` pointer param
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `fn` pointer params
   --> $DIR/where-allowed.rs:24:38
    |
 LL | fn in_fn_parameter_in_return() -> fn(impl Debug) { panic!() }
    |                                      ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `fn` pointer return
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `fn` pointer return types
   --> $DIR/where-allowed.rs:28:40
    |
 LL | fn in_fn_return_in_return() -> fn() -> impl Debug { panic!() }
    |                                        ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait param
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait params
   --> $DIR/where-allowed.rs:32:49
    |
 LL | fn in_dyn_Fn_parameter_in_parameters(_: &dyn Fn(impl Debug)) { panic!() }
    |                                                 ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait return
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait return types
   --> $DIR/where-allowed.rs:36:51
    |
 LL | fn in_dyn_Fn_return_in_parameters(_: &dyn Fn() -> impl Debug) { panic!() }
    |                                                   ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait param
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait params
   --> $DIR/where-allowed.rs:40:55
    |
 LL | fn in_dyn_Fn_parameter_in_return() -> &'static dyn Fn(impl Debug) { panic!() }
    |                                                       ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait param
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait params
   --> $DIR/where-allowed.rs:47:51
    |
 LL | fn in_impl_Fn_parameter_in_parameters(_: &impl Fn(impl Debug)) { panic!() }
    |                                                   ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait return
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait return types
   --> $DIR/where-allowed.rs:52:53
    |
 LL | fn in_impl_Fn_return_in_parameters(_: &impl Fn() -> impl Debug) { panic!() }
    |                                                     ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait param
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait params
   --> $DIR/where-allowed.rs:56:57
    |
 LL | fn in_impl_Fn_parameter_in_return() -> &'static impl Fn(impl Debug) { panic!() }
    |                                                         ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait param
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait params
   --> $DIR/where-allowed.rs:64:38
    |
 LL | fn in_Fn_parameter_in_generics<F: Fn(impl Debug)> (_: F) { panic!() }
    |                                      ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait return
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait return types
   --> $DIR/where-allowed.rs:68:40
    |
 LL | fn in_Fn_return_in_generics<F: Fn() -> impl Debug> (_: F) { panic!() }
    |                                        ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in field type
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in field types
   --> $DIR/where-allowed.rs:81:32
    |
 LL | struct InBraceStructField { x: impl Debug }
    |                                ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in field type
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in field types
   --> $DIR/where-allowed.rs:85:41
    |
 LL | struct InAdtInBraceStructField { x: Vec<impl Debug> }
    |                                         ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in field type
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in field types
   --> $DIR/where-allowed.rs:89:27
    |
 LL | struct InTupleStructField(impl Debug);
    |                           ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in field type
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in field types
   --> $DIR/where-allowed.rs:94:25
    |
 LL |     InBraceVariant { x: impl Debug },
    |                         ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in field type
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in field types
   --> $DIR/where-allowed.rs:96:20
    |
 LL |     InTupleVariant(impl Debug),
    |                    ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in trait method return
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in trait method return types
   --> $DIR/where-allowed.rs:107:23
    |
 LL |     fn in_return() -> impl Debug;
@@ -154,7 +154,7 @@ LL |     fn in_return() -> impl Debug;
    = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
    = help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `impl` method return
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `impl` method return types
   --> $DIR/where-allowed.rs:124:34
    |
 LL |     fn in_trait_impl_return() -> impl Debug { () }
@@ -163,121 +163,121 @@ LL |     fn in_trait_impl_return() -> impl Debug { () }
    = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
    = help: add `#![feature(return_position_impl_trait_in_trait)]` to the crate attributes to enable
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `extern fn` param
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `extern fn` params
   --> $DIR/where-allowed.rs:137:33
    |
 LL |     fn in_foreign_parameters(_: impl Debug);
    |                                 ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `extern fn` return
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `extern fn` return types
   --> $DIR/where-allowed.rs:140:31
    |
 LL |     fn in_foreign_return() -> impl Debug;
    |                               ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `fn` pointer return
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `fn` pointer return types
   --> $DIR/where-allowed.rs:156:39
    |
 LL | type InReturnInTypeAlias<R> = fn() -> impl Debug;
    |                                       ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in trait
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in traits
   --> $DIR/where-allowed.rs:161:16
    |
 LL | impl PartialEq<impl Debug> for () {
    |                ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in impl header
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in impl headers
   --> $DIR/where-allowed.rs:166:24
    |
 LL | impl PartialEq<()> for impl Debug {
    |                        ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in impl header
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in impl headers
   --> $DIR/where-allowed.rs:171:6
    |
 LL | impl impl Debug {
    |      ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in impl header
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in impl headers
   --> $DIR/where-allowed.rs:177:24
    |
 LL | impl InInherentImplAdt<impl Debug> {
    |                        ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in bound
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in bounds
   --> $DIR/where-allowed.rs:183:11
    |
 LL |     where impl Debug: Debug
    |           ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in bound
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in bounds
   --> $DIR/where-allowed.rs:190:15
    |
 LL |     where Vec<impl Debug>: Debug
    |               ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in bound
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in bounds
   --> $DIR/where-allowed.rs:197:24
    |
 LL |     where T: PartialEq<impl Debug>
    |                        ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait param
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait params
   --> $DIR/where-allowed.rs:204:17
    |
 LL |     where T: Fn(impl Debug)
    |                 ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait return
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `Fn` trait return types
   --> $DIR/where-allowed.rs:211:22
    |
 LL |     where T: Fn() -> impl Debug
    |                      ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generic parameter default
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generic parameter defaults
   --> $DIR/where-allowed.rs:217:40
    |
 LL | struct InStructGenericParamDefault<T = impl Debug>(T);
    |                                        ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generic parameter default
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generic parameter defaults
   --> $DIR/where-allowed.rs:221:36
    |
 LL | enum InEnumGenericParamDefault<T = impl Debug> { Variant(T) }
    |                                    ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generic parameter default
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generic parameter defaults
   --> $DIR/where-allowed.rs:225:38
    |
 LL | trait InTraitGenericParamDefault<T = impl Debug> {}
    |                                      ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generic parameter default
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generic parameter defaults
   --> $DIR/where-allowed.rs:229:41
    |
 LL | type InTypeAliasGenericParamDefault<T = impl Debug> = T;
    |                                         ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generic parameter default
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generic parameter defaults
   --> $DIR/where-allowed.rs:233:11
    |
 LL | impl <T = impl Debug> T {}
    |           ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generic parameter default
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generic parameter defaults
   --> $DIR/where-allowed.rs:240:40
    |
 LL | fn in_method_generic_param_default<T = impl Debug>(_: T) {}
    |                                        ^^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable binding
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable bindings
   --> $DIR/where-allowed.rs:246:29
    |
 LL |     let _in_local_variable: impl Fn() = || {};
    |                             ^^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in closure return
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in closure return types
   --> $DIR/where-allowed.rs:248:46
    |
 LL |     let _in_return_in_local_variable = || -> impl Fn() { || {} };
diff --git a/tests/ui/issues/issue-47715.stderr b/tests/ui/issues/issue-47715.stderr
index 0ee9388bf2b..dadea34b688 100644
--- a/tests/ui/issues/issue-47715.stderr
+++ b/tests/ui/issues/issue-47715.stderr
@@ -1,22 +1,22 @@
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generic
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generics
   --> $DIR/issue-47715.rs:9:37
    |
 LL | struct Container<T: Iterable<Item = impl Foo>> {
    |                                     ^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generic
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generics
   --> $DIR/issue-47715.rs:14:30
    |
 LL | enum Enum<T: Iterable<Item = impl Foo>> {
    |                              ^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generic
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generics
   --> $DIR/issue-47715.rs:19:32
    |
 LL | union Union<T: Iterable<Item = impl Foo> + Copy> {
    |                                ^^^^^^^^
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generic
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in generics
   --> $DIR/issue-47715.rs:24:30
    |
 LL | type Type<T: Iterable<Item = impl Foo>> = T;
diff --git a/tests/ui/type-alias-impl-trait/type-alias-impl-trait-fn-type.stderr b/tests/ui/type-alias-impl-trait/type-alias-impl-trait-fn-type.stderr
index a31cf1a51cc..ff375b2ff86 100644
--- a/tests/ui/type-alias-impl-trait/type-alias-impl-trait-fn-type.stderr
+++ b/tests/ui/type-alias-impl-trait/type-alias-impl-trait-fn-type.stderr
@@ -1,4 +1,4 @@
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `fn` pointer return
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in `fn` pointer return types
   --> $DIR/type-alias-impl-trait-fn-type.rs:6:20
    |
 LL | type Foo = fn() -> impl Send;
diff --git a/tests/ui/typeck/issue-104513-ice.stderr b/tests/ui/typeck/issue-104513-ice.stderr
index 42cfe38aed8..09187d7863a 100644
--- a/tests/ui/typeck/issue-104513-ice.stderr
+++ b/tests/ui/typeck/issue-104513-ice.stderr
@@ -4,7 +4,7 @@ error[E0405]: cannot find trait `Oops` in this scope
 LL |     let _: S<impl Oops> = S;
    |                   ^^^^ not found in this scope
 
-error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable binding
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in variable bindings
   --> $DIR/issue-104513-ice.rs:3:14
    |
 LL |     let _: S<impl Oops> = S;