Remove useless LocalDefId in ImplTraitContext::Universal.

Author: cjgillot

compiler/rustc_ast_lowering/src/item.rs

@@ -266,7 +266,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     let body_id =
                         this.lower_maybe_async_body(span, &decl, asyncness, body.as_deref());
 
-                    let itctx = ImplTraitContext::Universal(this.current_hir_id_owner);
+                    let itctx = ImplTraitContext::Universal;
                     let (generics, decl) = this.lower_generics(generics, id, itctx, |this| {
                         let ret_id = asyncness.opt_return_id();
                         this.lower_fn_decl(&decl, Some(id), FnDeclKind::Fn, ret_id)
@@ -385,7 +385,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 // method, it will not be considered an in-band
                 // lifetime to be added, but rather a reference to a
                 // parent lifetime.
-                let itctx = ImplTraitContext::Universal(self.current_hir_id_owner);
+                let itctx = ImplTraitContext::Universal;
                 let (generics, (trait_ref, lowered_ty)) =
                     self.lower_generics(ast_generics, id, itctx, |this| {
                         let trait_ref = trait_ref.as_ref().map(|trait_ref| {
@@ -655,7 +655,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             kind: match i.kind {
                 ForeignItemKind::Fn(box Fn { ref sig, ref generics, .. }) => {
                     let fdec = &sig.decl;
-                    let itctx = ImplTraitContext::Universal(self.current_hir_id_owner);
+                    let itctx = ImplTraitContext::Universal;
                     let (generics, (fn_dec, fn_args)) =
                         self.lower_generics(generics, i.id, itctx, |this| {
                             (
@@ -1237,7 +1237,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
         is_async: Option<NodeId>,
     ) -> (&'hir hir::Generics<'hir>, hir::FnSig<'hir>) {
         let header = self.lower_fn_header(sig.header);
-        let itctx = ImplTraitContext::Universal(self.current_hir_id_owner);
+        let itctx = ImplTraitContext::Universal;
         let (generics, decl) = self.lower_generics(generics, id, itctx, |this| {
             this.lower_fn_decl(&sig.decl, Some(id), kind, is_async)
         });

compiler/rustc_ast_lowering/src/lib.rs

@@ -253,7 +253,7 @@ enum ImplTraitContext {
     /// equivalent to a fresh universal parameter like `fn foo<T: Debug>(x: T)`.
     ///
     /// Newly generated parameters should be inserted into the given `Vec`.
-    Universal(LocalDefId),
+    Universal,
 
     /// Treat `impl Trait` as shorthand for a new opaque type.
     /// Example: `fn foo() -> impl Debug`, where `impl Debug` is conceptually
@@ -895,7 +895,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 hir::TypeBindingKind::Equality { term }
             }
             AssocConstraintKind::Bound { ref bounds } => {
-                let mut parent_def_id = self.current_hir_id_owner;
                 // Piggy-back on the `impl Trait` context to figure out the correct behavior.
                 let (desugar_to_impl_trait, itctx) = match itctx {
                     // We are in the return position:
@@ -915,10 +914,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     // so desugar to
                     //
                     //     fn foo(x: dyn Iterator<Item = impl Debug>)
-                    ImplTraitContext::Universal(parent) if self.is_in_dyn_type => {
-                        parent_def_id = parent;
-                        (true, itctx)
-                    }
+                    ImplTraitContext::Universal if self.is_in_dyn_type => (true, itctx),
 
                     // In `type Foo = dyn Iterator<Item: Debug>` we desugar to
                     // `type Foo = dyn Iterator<Item = impl Debug>` but we have to override the
@@ -944,6 +940,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     // Desugar `AssocTy: Bounds` into `AssocTy = impl Bounds`. We do this by
                     // constructing the HIR for `impl bounds...` and then lowering that.
 
+                    let parent_def_id = self.current_hir_id_owner;
                     let impl_trait_node_id = self.resolver.next_node_id();
                     self.resolver.create_def(
                         parent_def_id,
@@ -1186,12 +1183,12 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                             |this| this.lower_param_bounds(bounds, nested_itctx),
                         )
                     }
-                    ImplTraitContext::Universal(parent_def_id) => {
+                    ImplTraitContext::Universal => {
                         // Add a definition for the in-band `Param`.
                         let def_id = self.resolver.local_def_id(def_node_id);
 
-                        let hir_bounds = self
-                            .lower_param_bounds(bounds, ImplTraitContext::Universal(parent_def_id));
+                        let hir_bounds =
+                            self.lower_param_bounds(bounds, ImplTraitContext::Universal);
                         // Set the name to `impl Bound1 + Bound2`.
                         let ident = Ident::from_str_and_span(&pprust::ty_to_string(t), span);
                         let param = hir::GenericParam {
@@ -1401,10 +1398,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         }
         let inputs = self.arena.alloc_from_iter(inputs.iter().map(|param| {
             if fn_node_id.is_some() {
-                self.lower_ty_direct(
-                    &param.ty,
-                    ImplTraitContext::Universal(self.current_hir_id_owner),
-                )
+                self.lower_ty_direct(&param.ty, ImplTraitContext::Universal)
             } else {
                 self.lower_ty_direct(
                     &param.ty,