Rollup merge of #120750 - compiler-errors:itctx-by-val, r=cjgillot

No need to take `ImplTraitContext` by ref

We used to mutate `ImplTraitContext`, so it used to be `&mut` mutable ref. Then I think it used to have non-`Copy` data in it, so we took it by `&` ref. Now, none of that remains, so just copy it around.

8 files changed, 90 insertions, 92 deletions

diff --git a/compiler/rustc_ast_lowering/src/asm.rs b/compiler/rustc_ast_lowering/src/asm.rs
index 3742cf9d881..fd717e82d26 100644
--- a/compiler/rustc_ast_lowering/src/asm.rs
+++ b/compiler/rustc_ast_lowering/src/asm.rs
@@ -205,7 +205,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                                 &sym.qself,
                                 &sym.path,
                                 ParamMode::Optional,
-                                &ImplTraitContext::Disallowed(ImplTraitPosition::Path),
+                                ImplTraitContext::Disallowed(ImplTraitPosition::Path),
                                 None,
                             );
                             hir::InlineAsmOperand::SymStatic { path, def_id }
diff --git a/compiler/rustc_ast_lowering/src/block.rs b/compiler/rustc_ast_lowering/src/block.rs
index d310f72f7a3..865a56b2c1f 100644
--- a/compiler/rustc_ast_lowering/src/block.rs
+++ b/compiler/rustc_ast_lowering/src/block.rs
@@ -85,7 +85,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         let ty = l
             .ty
             .as_ref()
-            .map(|t| self.lower_ty(t, &ImplTraitContext::Disallowed(ImplTraitPosition::Variable)));
+            .map(|t| self.lower_ty(t, ImplTraitContext::Disallowed(ImplTraitPosition::Variable)));
         let init = l.kind.init().map(|init| self.lower_expr(init));
         let hir_id = self.lower_node_id(l.id);
         let pat = self.lower_pat(&l.pat);
diff --git a/compiler/rustc_ast_lowering/src/delegation.rs b/compiler/rustc_ast_lowering/src/delegation.rs
index 6ccf39b0cb1..d1ba93f0675 100644
--- a/compiler/rustc_ast_lowering/src/delegation.rs
+++ b/compiler/rustc_ast_lowering/src/delegation.rs
@@ -218,7 +218,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             &delegation.qself,
             &delegation.path,
             ParamMode::Optional,
-            &ImplTraitContext::Disallowed(ImplTraitPosition::Path),
+            ImplTraitContext::Disallowed(ImplTraitPosition::Path),
             None,
         );
         let block = delegation.body.as_deref();
diff --git a/compiler/rustc_ast_lowering/src/expr.rs b/compiler/rustc_ast_lowering/src/expr.rs
index c4798887637..942aae3d536 100644
--- a/compiler/rustc_ast_lowering/src/expr.rs
+++ b/compiler/rustc_ast_lowering/src/expr.rs
@@ -99,7 +99,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         seg,
                         ParamMode::Optional,
                         ParenthesizedGenericArgs::Err,
-                        &ImplTraitContext::Disallowed(ImplTraitPosition::Path),
+                        ImplTraitContext::Disallowed(ImplTraitPosition::Path),
                         None,
                         // Method calls can't have bound modifiers
                         None,
@@ -141,13 +141,13 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 ExprKind::Cast(expr, ty) => {
                     let expr = self.lower_expr(expr);
                     let ty =
-                        self.lower_ty(ty, &ImplTraitContext::Disallowed(ImplTraitPosition::Cast));
+                        self.lower_ty(ty, ImplTraitContext::Disallowed(ImplTraitPosition::Cast));
                     hir::ExprKind::Cast(expr, ty)
                 }
                 ExprKind::Type(expr, ty) => {
                     let expr = self.lower_expr(expr);
                     let ty =
-                        self.lower_ty(ty, &ImplTraitContext::Disallowed(ImplTraitPosition::Cast));
+                        self.lower_ty(ty, ImplTraitContext::Disallowed(ImplTraitPosition::Cast));
                     hir::ExprKind::Type(expr, ty)
                 }
                 ExprKind::AddrOf(k, m, ohs) => {
@@ -267,7 +267,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         qself,
                         path,
                         ParamMode::Optional,
-                        &ImplTraitContext::Disallowed(ImplTraitPosition::Path),
+                        ImplTraitContext::Disallowed(ImplTraitPosition::Path),
                         None,
                     );
                     hir::ExprKind::Path(qpath)
@@ -295,7 +295,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 ExprKind::OffsetOf(container, fields) => hir::ExprKind::OffsetOf(
                     self.lower_ty(
                         container,
-                        &ImplTraitContext::Disallowed(ImplTraitPosition::OffsetOf),
+                        ImplTraitContext::Disallowed(ImplTraitPosition::OffsetOf),
                     ),
                     self.arena.alloc_from_iter(fields.iter().map(|&ident| self.lower_ident(ident))),
                 ),
@@ -314,7 +314,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                             &se.qself,
                             &se.path,
                             ParamMode::Optional,
-                            &ImplTraitContext::Disallowed(ImplTraitPosition::Path),
+                            ImplTraitContext::Disallowed(ImplTraitPosition::Path),
                             None,
                         )),
                         self.arena
@@ -1241,7 +1241,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         qself,
                         path,
                         ParamMode::Optional,
-                        &ImplTraitContext::Disallowed(ImplTraitPosition::Path),
+                        ImplTraitContext::Disallowed(ImplTraitPosition::Path),
                         None,
                     );
                     // Destructure like a tuple struct.
@@ -1261,7 +1261,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         qself,
                         path,
                         ParamMode::Optional,
-                        &ImplTraitContext::Disallowed(ImplTraitPosition::Path),
+                        ImplTraitContext::Disallowed(ImplTraitPosition::Path),
                         None,
                     );
                     // Destructure like a unit struct.
@@ -1286,7 +1286,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     &se.qself,
                     &se.path,
                     ParamMode::Optional,
-                    &ImplTraitContext::Disallowed(ImplTraitPosition::Path),
+                    ImplTraitContext::Disallowed(ImplTraitPosition::Path),
                     None,
                 );
                 let fields_omitted = match &se.rest {
diff --git a/compiler/rustc_ast_lowering/src/item.rs b/compiler/rustc_ast_lowering/src/item.rs
index 7b81ed4875c..75410323f97 100644
--- a/compiler/rustc_ast_lowering/src/item.rs
+++ b/compiler/rustc_ast_lowering/src/item.rs
@@ -189,7 +189,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     generics,
                     Const::No,
                     id,
-                    &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
+                    ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| {
                         this.lower_const_item(ty, span, expr.as_deref(), ImplTraitPosition::ConstTy)
                     },
@@ -218,7 +218,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
 
                     let itctx = ImplTraitContext::Universal;
                     let (generics, decl) =
-                        this.lower_generics(generics, header.constness, id, &itctx, |this| {
+                        this.lower_generics(generics, header.constness, id, itctx, |this| {
                             this.lower_fn_decl(
                                 decl,
                                 id,
@@ -263,7 +263,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     &generics,
                     Const::No,
                     id,
-                    &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
+                    ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| match ty {
                         None => {
                             let guar = this.dcx().span_delayed_bug(
@@ -274,7 +274,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         }
                         Some(ty) => this.lower_ty(
                             ty,
-                            &ImplTraitContext::TypeAliasesOpaqueTy { in_assoc_ty: false },
+                            ImplTraitContext::TypeAliasesOpaqueTy { in_assoc_ty: false },
                         ),
                     },
                 );
@@ -285,7 +285,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     generics,
                     Const::No,
                     id,
-                    &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
+                    ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| {
                         this.arena.alloc_from_iter(
                             enum_definition.variants.iter().map(|x| this.lower_variant(x)),
@@ -299,7 +299,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     generics,
                     Const::No,
                     id,
-                    &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
+                    ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| this.lower_variant_data(hir_id, struct_def),
                 );
                 hir::ItemKind::Struct(struct_def, generics)
@@ -309,7 +309,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     generics,
                     Const::No,
                     id,
-                    &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
+                    ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| this.lower_variant_data(hir_id, vdata),
                 );
                 hir::ItemKind::Union(vdata, generics)
@@ -339,7 +339,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 // parent lifetime.
                 let itctx = ImplTraitContext::Universal;
                 let (generics, (trait_ref, lowered_ty)) =
-                    self.lower_generics(ast_generics, *constness, id, &itctx, |this| {
+                    self.lower_generics(ast_generics, *constness, id, itctx, |this| {
                         let modifiers = TraitBoundModifiers {
                             constness: match *constness {
                                 Const::Yes(span) => BoundConstness::Maybe(span),
@@ -354,13 +354,13 @@ impl<'hir> LoweringContext<'_, 'hir> {
                             this.lower_trait_ref(
                                 modifiers,
                                 trait_ref,
-                                &ImplTraitContext::Disallowed(ImplTraitPosition::Trait),
+                                ImplTraitContext::Disallowed(ImplTraitPosition::Trait),
                             )
                         });
 
                         let lowered_ty = this.lower_ty(
                             ty,
-                            &ImplTraitContext::Disallowed(ImplTraitPosition::ImplSelf),
+                            ImplTraitContext::Disallowed(ImplTraitPosition::ImplSelf),
                         );
 
                         (trait_ref, lowered_ty)
@@ -400,11 +400,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     generics,
                     constness,
                     id,
-                    &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
+                    ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| {
                         let bounds = this.lower_param_bounds(
                             bounds,
-                            &ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
+                            ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
                         );
                         let items = this.arena.alloc_from_iter(
                             items.iter().map(|item| this.lower_trait_item_ref(item)),
@@ -420,11 +420,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     generics,
                     Const::No,
                     id,
-                    &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
+                    ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| {
                         this.lower_param_bounds(
                             bounds,
-                            &ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
+                            ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
                         )
                     },
                 );
@@ -464,7 +464,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         body: Option<&Expr>,
         impl_trait_position: ImplTraitPosition,
     ) -> (&'hir hir::Ty<'hir>, hir::BodyId) {
-        let ty = self.lower_ty(ty, &ImplTraitContext::Disallowed(impl_trait_position));
+        let ty = self.lower_ty(ty, ImplTraitContext::Disallowed(impl_trait_position));
         (ty, self.lower_const_body(span, body))
     }
 
@@ -633,7 +633,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     let fdec = &sig.decl;
                     let itctx = ImplTraitContext::Universal;
                     let (generics, (fn_dec, fn_args)) =
-                        self.lower_generics(generics, Const::No, i.id, &itctx, |this| {
+                        self.lower_generics(generics, Const::No, i.id, itctx, |this| {
                             (
                                 // Disallow `impl Trait` in foreign items.
                                 this.lower_fn_decl(
@@ -650,8 +650,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     hir::ForeignItemKind::Fn(fn_dec, fn_args, generics)
                 }
                 ForeignItemKind::Static(t, m, _) => {
-                    let ty = self
-                        .lower_ty(t, &ImplTraitContext::Disallowed(ImplTraitPosition::StaticTy));
+                    let ty =
+                        self.lower_ty(t, ImplTraitContext::Disallowed(ImplTraitPosition::StaticTy));
                     hir::ForeignItemKind::Static(ty, *m)
                 }
                 ForeignItemKind::TyAlias(..) => hir::ForeignItemKind::Type,
@@ -722,11 +722,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 qself,
                 path,
                 ParamMode::ExplicitNamed, // no `'_` in declarations (Issue #61124)
-                &ImplTraitContext::Disallowed(ImplTraitPosition::FieldTy),
+                ImplTraitContext::Disallowed(ImplTraitPosition::FieldTy),
             );
             self.arena.alloc(t)
         } else {
-            self.lower_ty(&f.ty, &ImplTraitContext::Disallowed(ImplTraitPosition::FieldTy))
+            self.lower_ty(&f.ty, ImplTraitContext::Disallowed(ImplTraitPosition::FieldTy))
         };
         let hir_id = self.lower_node_id(f.id);
         self.lower_attrs(hir_id, &f.attrs);
@@ -755,12 +755,10 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     generics,
                     Const::No,
                     i.id,
-                    &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
+                    ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| {
-                        let ty = this.lower_ty(
-                            ty,
-                            &ImplTraitContext::Disallowed(ImplTraitPosition::ConstTy),
-                        );
+                        let ty = this
+                            .lower_ty(ty, ImplTraitContext::Disallowed(ImplTraitPosition::ConstTy));
                         let body = expr.as_ref().map(|x| this.lower_const_body(i.span, Some(x)));
 
                         hir::TraitItemKind::Const(ty, body)
@@ -803,18 +801,18 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     &generics,
                     Const::No,
                     i.id,
-                    &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
+                    ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| {
                         let ty = ty.as_ref().map(|x| {
                             this.lower_ty(
                                 x,
-                                &ImplTraitContext::Disallowed(ImplTraitPosition::AssocTy),
+                                ImplTraitContext::Disallowed(ImplTraitPosition::AssocTy),
                             )
                         });
                         hir::TraitItemKind::Type(
                             this.lower_param_bounds(
                                 bounds,
-                                &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
+                                ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                             ),
                             ty,
                         )
@@ -882,10 +880,10 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 generics,
                 Const::No,
                 i.id,
-                &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
+                ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                 |this| {
-                    let ty = this
-                        .lower_ty(ty, &ImplTraitContext::Disallowed(ImplTraitPosition::ConstTy));
+                    let ty =
+                        this.lower_ty(ty, ImplTraitContext::Disallowed(ImplTraitPosition::ConstTy));
                     let body = this.lower_const_body(i.span, expr.as_deref());
 
                     hir::ImplItemKind::Const(ty, body)
@@ -916,7 +914,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     &generics,
                     Const::No,
                     i.id,
-                    &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
+                    ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| match ty {
                         None => {
                             let guar = this.dcx().span_delayed_bug(
@@ -929,7 +927,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                         Some(ty) => {
                             let ty = this.lower_ty(
                                 ty,
-                                &ImplTraitContext::TypeAliasesOpaqueTy { in_assoc_ty: true },
+                                ImplTraitContext::TypeAliasesOpaqueTy { in_assoc_ty: true },
                             );
                             hir::ImplItemKind::Type(ty)
                         }
@@ -1323,7 +1321,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         // synthesize a host effect param for them. We reject `const` on them during AST validation.
         let constness = if kind == FnDeclKind::Inherent { sig.header.constness } else { Const::No };
         let itctx = ImplTraitContext::Universal;
-        let (generics, decl) = self.lower_generics(generics, constness, id, &itctx, |this| {
+        let (generics, decl) = self.lower_generics(generics, constness, id, itctx, |this| {
             this.lower_fn_decl(&sig.decl, id, sig.span, kind, coroutine_kind)
         });
         (generics, hir::FnSig { header, decl, span: self.lower_span(sig.span) })
@@ -1401,7 +1399,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         generics: &Generics,
         constness: Const,
         parent_node_id: NodeId,
-        itctx: &ImplTraitContext,
+        itctx: ImplTraitContext,
         f: impl FnOnce(&mut Self) -> T,
     ) -> (&'hir hir::Generics<'hir>, T) {
         debug_assert!(self.impl_trait_defs.is_empty());
@@ -1607,7 +1605,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         bounds: &[GenericBound],
         colon_span: Option<Span>,
         parent_span: Span,
-        itctx: &ImplTraitContext,
+        itctx: ImplTraitContext,
         origin: PredicateOrigin,
     ) -> Option<hir::WherePredicate<'hir>> {
         // Do not create a clause if we do not have anything inside it.
@@ -1681,10 +1679,10 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 bound_generic_params: self
                     .lower_generic_params(bound_generic_params, hir::GenericParamSource::Binder),
                 bounded_ty: self
-                    .lower_ty(bounded_ty, &ImplTraitContext::Disallowed(ImplTraitPosition::Bound)),
+                    .lower_ty(bounded_ty, ImplTraitContext::Disallowed(ImplTraitPosition::Bound)),
                 bounds: self.lower_param_bounds(
                     bounds,
-                    &ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
+                    ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
                 ),
                 span: self.lower_span(*span),
                 origin: PredicateOrigin::WhereClause,
@@ -1695,7 +1693,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     lifetime: self.lower_lifetime(lifetime),
                     bounds: self.lower_param_bounds(
                         bounds,
-                        &ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
+                        ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
                     ),
                     in_where_clause: true,
                 })
@@ -1703,9 +1701,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
             WherePredicate::EqPredicate(WhereEqPredicate { lhs_ty, rhs_ty, span }) => {
                 hir::WherePredicate::EqPredicate(hir::WhereEqPredicate {
                     lhs_ty: self
-                        .lower_ty(lhs_ty, &ImplTraitContext::Disallowed(ImplTraitPosition::Bound)),
+                        .lower_ty(lhs_ty, ImplTraitContext::Disallowed(ImplTraitPosition::Bound)),
                     rhs_ty: self
-                        .lower_ty(rhs_ty, &ImplTraitContext::Disallowed(ImplTraitPosition::Bound)),
+                        .lower_ty(rhs_ty, ImplTraitContext::Disallowed(ImplTraitPosition::Bound)),
                     span: self.lower_span(*span),
                 })
             }
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index 3f382627076..b570a0611c3 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -1007,7 +1007,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     fn lower_assoc_ty_constraint(
         &mut self,
         constraint: &AssocConstraint,
-        itctx: &ImplTraitContext,
+        itctx: ImplTraitContext,
     ) -> hir::TypeBinding<'hir> {
         debug!("lower_assoc_ty_constraint(constraint={:?}, itctx={:?})", constraint, itctx);
         // lower generic arguments of identifier in constraint
@@ -1086,9 +1086,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 hir::TypeBindingKind::Equality { term }
             }
             AssocConstraintKind::Bound { bounds } => {
-                enum DesugarKind<'a> {
+                enum DesugarKind {
                     ImplTrait,
-                    Error(&'a ImplTraitPosition),
+                    Error(ImplTraitPosition),
                     Bound,
                 }
 
@@ -1164,7 +1164,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     DesugarKind::Error(position) => {
                         let guar = self.dcx().emit_err(errors::MisplacedAssocTyBinding {
                             span: constraint.span,
-                            position: DiagnosticArgFromDisplay(position),
+                            position: DiagnosticArgFromDisplay(&position),
                         });
                         let err_ty =
                             &*self.arena.alloc(self.ty(constraint.span, hir::TyKind::Err(guar)));
@@ -1211,7 +1211,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     fn lower_generic_arg(
         &mut self,
         arg: &ast::GenericArg,
-        itctx: &ImplTraitContext,
+        itctx: ImplTraitContext,
     ) -> hir::GenericArg<'hir> {
         match arg {
             ast::GenericArg::Lifetime(lt) => GenericArg::Lifetime(self.lower_lifetime(lt)),
@@ -1290,7 +1290,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     }
 
     #[instrument(level = "debug", skip(self))]
-    fn lower_ty(&mut self, t: &Ty, itctx: &ImplTraitContext) -> &'hir hir::Ty<'hir> {
+    fn lower_ty(&mut self, t: &Ty, itctx: ImplTraitContext) -> &'hir hir::Ty<'hir> {
         self.arena.alloc(self.lower_ty_direct(t, itctx))
     }
 
@@ -1300,7 +1300,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         qself: &Option<ptr::P<QSelf>>,
         path: &Path,
         param_mode: ParamMode,
-        itctx: &ImplTraitContext,
+        itctx: ImplTraitContext,
     ) -> hir::Ty<'hir> {
         // Check whether we should interpret this as a bare trait object.
         // This check mirrors the one in late resolution. We only introduce this special case in
@@ -1342,7 +1342,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         self.ty(span, hir::TyKind::Tup(tys))
     }
 
-    fn lower_ty_direct(&mut self, t: &Ty, itctx: &ImplTraitContext) -> hir::Ty<'hir> {
+    fn lower_ty_direct(&mut self, t: &Ty, itctx: ImplTraitContext) -> hir::Ty<'hir> {
         let kind = match &t.kind {
             TyKind::Infer => hir::TyKind::Infer,
             TyKind::Err => {
@@ -1461,13 +1461,13 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     ImplTraitContext::ReturnPositionOpaqueTy { origin, fn_kind } => self
                         .lower_opaque_impl_trait(
                             span,
-                            *origin,
+                            origin,
                             *def_node_id,
                             bounds,
-                            Some(*fn_kind),
+                            Some(fn_kind),
                             itctx,
                         ),
-                    &ImplTraitContext::TypeAliasesOpaqueTy { in_assoc_ty } => self
+                    ImplTraitContext::TypeAliasesOpaqueTy { in_assoc_ty } => self
                         .lower_opaque_impl_trait(
                             span,
                             hir::OpaqueTyOrigin::TyAlias { in_assoc_ty },
@@ -1514,9 +1514,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                             .create_feature_err(
                                 MisplacedImplTrait {
                                     span: t.span,
-                                    position: DiagnosticArgFromDisplay(position),
+                                    position: DiagnosticArgFromDisplay(&position),
                                 },
-                                *feature,
+                                feature,
                             )
                             .emit();
                         hir::TyKind::Err(guar)
@@ -1524,7 +1524,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     ImplTraitContext::Disallowed(position) => {
                         let guar = self.dcx().emit_err(MisplacedImplTrait {
                             span: t.span,
-                            position: DiagnosticArgFromDisplay(position),
+                            position: DiagnosticArgFromDisplay(&position),
                         });
                         hir::TyKind::Err(guar)
                     }
@@ -1582,7 +1582,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         opaque_ty_node_id: NodeId,
         bounds: &GenericBounds,
         fn_kind: Option<FnDeclKind>,
-        itctx: &ImplTraitContext,
+        itctx: ImplTraitContext,
     ) -> hir::TyKind<'hir> {
         // Make sure we know that some funky desugaring has been going on here.
         // This is a first: there is code in other places like for loop
@@ -1849,7 +1849,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     ImplTraitContext::Disallowed(ImplTraitPosition::PointerParam)
                 }
             };
-            self.lower_ty_direct(&param.ty, &itctx)
+            self.lower_ty_direct(&param.ty, itctx)
         }));
 
         let output = match coro {
@@ -1877,7 +1877,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                             ImplTraitContext::Disallowed(ImplTraitPosition::PointerReturn)
                         }
                     };
-                    hir::FnRetTy::Return(self.lower_ty(ty, &itctx))
+                    hir::FnRetTy::Return(self.lower_ty(ty, itctx))
                 }
                 FnRetTy::Default(span) => hir::FnRetTy::DefaultReturn(self.lower_span(*span)),
             },
@@ -1978,7 +1978,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         output: &FnRetTy,
         coro: CoroutineKind,
         opaque_ty_span: Span,
-        nested_impl_trait_context: ImplTraitContext,
+        itctx: ImplTraitContext,
     ) -> hir::GenericBound<'hir> {
         // Compute the `T` in `Future<Output = T>` from the return type.
         let output_ty = match output {
@@ -1986,7 +1986,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 // Not `OpaqueTyOrigin::AsyncFn`: that's only used for the
                 // `impl Future` opaque type that `async fn` implicitly
                 // generates.
-                self.lower_ty(ty, &nested_impl_trait_context)
+                self.lower_ty(ty, itctx)
             }
             FnRetTy::Default(ret_ty_span) => self.arena.alloc(self.ty_tup(*ret_ty_span, &[])),
         };
@@ -2026,7 +2026,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     fn lower_param_bound(
         &mut self,
         tpb: &GenericBound,
-        itctx: &ImplTraitContext,
+        itctx: ImplTraitContext,
     ) -> hir::GenericBound<'hir> {
         match tpb {
             GenericBound::Trait(p, modifiers) => hir::GenericBound::Trait(
@@ -2165,7 +2165,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     .map(|def| {
                         self.lower_ty(
                             def,
-                            &ImplTraitContext::Disallowed(ImplTraitPosition::GenericDefault),
+                            ImplTraitContext::Disallowed(ImplTraitPosition::GenericDefault),
                         )
                     });
 
@@ -2175,7 +2175,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             }
             GenericParamKind::Const { ty, kw_span: _, default } => {
                 let ty = self
-                    .lower_ty(ty, &ImplTraitContext::Disallowed(ImplTraitPosition::GenericDefault));
+                    .lower_ty(ty, ImplTraitContext::Disallowed(ImplTraitPosition::GenericDefault));
 
                 // Not only do we deny const param defaults in binders but we also map them to `None`
                 // since later compiler stages cannot handle them (and shouldn't need to be able to).
@@ -2205,7 +2205,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         &mut self,
         modifiers: ast::TraitBoundModifiers,
         p: &TraitRef,
-        itctx: &ImplTraitContext,
+        itctx: ImplTraitContext,
     ) -> hir::TraitRef<'hir> {
         let path = match self.lower_qpath(
             p.ref_id,
@@ -2225,7 +2225,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     fn lower_poly_trait_ref(
         &mut self,
         p: &PolyTraitRef,
-        itctx: &ImplTraitContext,
+        itctx: ImplTraitContext,
         modifiers: ast::TraitBoundModifiers,
     ) -> hir::PolyTraitRef<'hir> {
         let bound_generic_params =
@@ -2234,7 +2234,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         hir::PolyTraitRef { bound_generic_params, trait_ref, span: self.lower_span(p.span) }
     }
 
-    fn lower_mt(&mut self, mt: &MutTy, itctx: &ImplTraitContext) -> hir::MutTy<'hir> {
+    fn lower_mt(&mut self, mt: &MutTy, itctx: ImplTraitContext) -> hir::MutTy<'hir> {
         hir::MutTy { ty: self.lower_ty(&mt.ty, itctx), mutbl: mt.mutbl }
     }
 
@@ -2242,7 +2242,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     fn lower_param_bounds(
         &mut self,
         bounds: &[GenericBound],
-        itctx: &ImplTraitContext,
+        itctx: ImplTraitContext,
     ) -> hir::GenericBounds<'hir> {
         self.arena.alloc_from_iter(self.lower_param_bounds_mut(bounds, itctx))
     }
@@ -2250,7 +2250,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     fn lower_param_bounds_mut<'s>(
         &'s mut self,
         bounds: &'s [GenericBound],
-        itctx: &'s ImplTraitContext,
+        itctx: ImplTraitContext,
     ) -> impl Iterator<Item = hir::GenericBound<'hir>> + Captures<'s> + Captures<'a> {
         bounds.iter().map(move |bound| self.lower_param_bound(bound, itctx))
     }
@@ -2286,7 +2286,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             bounds,
             /* colon_span */ None,
             span,
-            &ImplTraitContext::Universal,
+            ImplTraitContext::Universal,
             hir::PredicateOrigin::ImplTrait,
         );
 
diff --git a/compiler/rustc_ast_lowering/src/pat.rs b/compiler/rustc_ast_lowering/src/pat.rs
index 0af141ff99a..c097feb6b34 100644
--- a/compiler/rustc_ast_lowering/src/pat.rs
+++ b/compiler/rustc_ast_lowering/src/pat.rs
@@ -38,7 +38,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                             qself,
                             path,
                             ParamMode::Optional,
-                            &ImplTraitContext::Disallowed(ImplTraitPosition::Path),
+                            ImplTraitContext::Disallowed(ImplTraitPosition::Path),
                             None,
                         );
                         let (pats, ddpos) = self.lower_pat_tuple(pats, "tuple struct");
@@ -55,7 +55,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                             qself,
                             path,
                             ParamMode::Optional,
-                            &ImplTraitContext::Disallowed(ImplTraitPosition::Path),
+                            ImplTraitContext::Disallowed(ImplTraitPosition::Path),
                             None,
                         );
                         break hir::PatKind::Path(qpath);
@@ -66,7 +66,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                             qself,
                             path,
                             ParamMode::Optional,
-                            &ImplTraitContext::Disallowed(ImplTraitPosition::Path),
+                            ImplTraitContext::Disallowed(ImplTraitPosition::Path),
                             None,
                         );
 
diff --git a/compiler/rustc_ast_lowering/src/path.rs b/compiler/rustc_ast_lowering/src/path.rs
index 76c7e530a6b..48941a232c2 100644
--- a/compiler/rustc_ast_lowering/src/path.rs
+++ b/compiler/rustc_ast_lowering/src/path.rs
@@ -27,7 +27,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         qself: &Option<ptr::P<QSelf>>,
         p: &Path,
         param_mode: ParamMode,
-        itctx: &ImplTraitContext,
+        itctx: ImplTraitContext,
         // modifiers of the impl/bound if this is a trait path
         modifiers: Option<ast::TraitBoundModifiers>,
     ) -> hir::QPath<'hir> {
@@ -205,7 +205,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     segment,
                     param_mode,
                     ParenthesizedGenericArgs::Err,
-                    &ImplTraitContext::Disallowed(ImplTraitPosition::Path),
+                    ImplTraitContext::Disallowed(ImplTraitPosition::Path),
                     None,
                     None,
                 )
@@ -220,7 +220,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         segment: &PathSegment,
         param_mode: ParamMode,
         parenthesized_generic_args: ParenthesizedGenericArgs,
-        itctx: &ImplTraitContext,
+        itctx: ImplTraitContext,
         constness: Option<ast::BoundConstness>,
         // Additional features ungated with a bound modifier like `async`.
         // This is passed down to the implicit associated type binding in
@@ -374,7 +374,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         &mut self,
         data: &AngleBracketedArgs,
         param_mode: ParamMode,
-        itctx: &ImplTraitContext,
+        itctx: ImplTraitContext,
     ) -> (GenericArgsCtor<'hir>, bool) {
         let has_non_lt_args = data.args.iter().any(|arg| match arg {
             AngleBracketedArg::Arg(ast::GenericArg::Lifetime(_))
@@ -405,7 +405,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     fn lower_parenthesized_parameter_data(
         &mut self,
         data: &ParenthesizedArgs,
-        itctx: &ImplTraitContext,
+        itctx: ImplTraitContext,
         bound_modifier_allowed_features: Option<Lrc<[Symbol]>>,
     ) -> (GenericArgsCtor<'hir>, bool) {
         // Switch to `PassThrough` mode for anonymous lifetimes; this
@@ -415,7 +415,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         // we generally don't permit such things (see #51008).
         let ParenthesizedArgs { span, inputs, inputs_span, output } = data;
         let inputs = self.arena.alloc_from_iter(inputs.iter().map(|ty| {
-            self.lower_ty_direct(ty, &ImplTraitContext::Disallowed(ImplTraitPosition::FnTraitParam))
+            self.lower_ty_direct(ty, ImplTraitContext::Disallowed(ImplTraitPosition::FnTraitParam))
         }));
         let output_ty = match output {
             // Only allow `impl Trait` in return position. i.e.:
@@ -429,7 +429,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 } else {
                     self.lower_ty(
                         ty,
-                        &ImplTraitContext::FeatureGated(
+                        ImplTraitContext::FeatureGated(
                             ImplTraitPosition::FnTraitReturn,
                             sym::impl_trait_in_fn_trait_return,
                         ),
@@ -437,7 +437,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 }
             }
             FnRetTy::Ty(ty) => {
-                self.lower_ty(ty, &ImplTraitContext::Disallowed(ImplTraitPosition::FnTraitReturn))
+                self.lower_ty(ty, ImplTraitContext::Disallowed(ImplTraitPosition::FnTraitReturn))
             }
             FnRetTy::Default(_) => self.arena.alloc(self.ty_tup(*span, &[])),
         };