Intern OpaqueTy on ItemKind::OpaqueTy

compiler/rustc_hir/src/hir.rs

@@ -3315,7 +3315,7 @@ pub enum ItemKind<'hir> {
     /// A type alias, e.g., `type Foo = Bar<u8>`.
     TyAlias(&'hir Ty<'hir>, &'hir Generics<'hir>),
     /// An opaque `impl Trait` type alias, e.g., `type Foo = impl Bar;`.
-    OpaqueTy(OpaqueTy<'hir>),
+    OpaqueTy(&'hir OpaqueTy<'hir>),
     /// An enum definition, e.g., `enum Foo<A, B> {C<A>, D<B>}`.
     Enum(EnumDef<'hir>, &'hir Generics<'hir>),
     /// A struct definition, e.g., `struct Foo<A> {x: A}`.