Remove superfluous traversable impl for ClosureKind

Author: eggyal

compiler/rustc_middle/src/ty/structural_impls.rs

@@ -410,6 +410,7 @@ TrivialLiftImpls! {
      u64,
      ::rustc_hir::def_id::DefId,
      ::rustc_hir::Mutability,
+     crate::ty::ClosureKind,
      crate::ty::ParamConst,
      crate::ty::ParamTy,
      interpret::Scalar,
@@ -431,7 +432,6 @@ TrivialTypeTraversalImpls! {
 TrivialTypeTraversalAndLiftImpls! {
     ::rustc_hir::Unsafety,
     ::rustc_target::spec::abi::Abi,
-    crate::ty::ClosureKind,
 }
 
 ///////////////////////////////////////////////////////////////////////////

compiler/rustc_type_ir/src/predicate_kind.rs

@@ -376,7 +376,7 @@ where
     I::Term: TypeFoldable<I>,
     I::CoercePredicate: TypeFoldable<I>,
     I::SubtypePredicate: TypeFoldable<I>,
-    I::ClosureKind: TypeFoldable<I>,
+    I::ClosureKind: BoringTraversable,
     ClauseKind<I>: TypeFoldable<I>,
 {
     fn try_fold_with<F: FallibleTypeFolder<I>>(self, folder: &mut F) -> Result<Self, F::Error> {
@@ -420,7 +420,7 @@ where
     I::Term: TypeVisitable<I>,
     I::CoercePredicate: TypeVisitable<I>,
     I::SubtypePredicate: TypeVisitable<I>,
-    I::ClosureKind: TypeVisitable<I>,
+    I::ClosureKind: BoringTraversable,
     ClauseKind<I>: TypeVisitable<I>,
 {
     fn visit_with<V: TypeVisitor<I>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {