diff options
| -rw-r--r-- | src/librustc/hir/lowering.rs | 33 |
1 files changed, 14 insertions, 19 deletions
diff --git a/src/librustc/hir/lowering.rs b/src/librustc/hir/lowering.rs index 06f9128cd22..4c96e106d1f 100644 --- a/src/librustc/hir/lowering.rs +++ b/src/librustc/hir/lowering.rs @@ -1381,33 +1381,30 @@ impl<'a> LoweringContext<'a> { let ty = match c.kind { AssocTyConstraintKind::Equality { ref ty } => self.lower_ty(ty, itctx), AssocTyConstraintKind::Bound { ref bounds } => { - // Piggy-back on the impl trait context to figure out - // the correct behavior. + // 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: // - // fn foo() -> impl Iterator<Item: Debug> + // fn foo() -> impl Iterator<Item: Debug> // // so desugar to // - // fn foo() -> impl Iterator<Item = impl Debug> + // fn foo() -> impl Iterator<Item = impl Debug> ImplTraitContext::Existential(_) => (true, itctx), // We are in the argument position, but within a dyn type: // - // fn foo(x: dyn Iterator<Item: Debug>) + // fn foo(x: dyn Iterator<Item: Debug>) // // so desugar to // - // fn foo(x: dyn Iterator<Item = impl Debug>) + // fn foo(x: dyn Iterator<Item = impl Debug>) 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 "impl trait - // context" to permit `impl Debug` in this - // position (it desugars then to an existential - // type). + // 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 existential type). // // FIXME: this is only needed until `impl Trait` is allowed in type aliases. ImplTraitContext::Disallowed(_) if self.is_in_dyn_type => @@ -1415,19 +1412,17 @@ impl<'a> LoweringContext<'a> { // We are in the argument position, but not within a dyn type: // - // fn foo(x: impl Iterator<Item: Debug>) + // fn foo(x: impl Iterator<Item: Debug>) // - // 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 + // 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), }; 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. + // 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.sess.next_node_id(); let parent_def_index = self.current_hir_id_owner.last().unwrap().0; |