Unify WalkItemKind

Author: maxcabrajac

compiler/rustc_ast/src/visitors.rs

@@ -1167,6 +1167,13 @@ macro_rules! make_ast_visitor {
             }
         }
 
+        pub trait WalkItemKind: Sized {
+            fn walk<$($lt,)? V: $trait$(<$lt>)?>(
+                item: ref_t!(Item<Self>),
+                visitor: &mut V,
+            ) -> result!(V);
+        }
+
         make_walk_flat_map!{Arm, walk_flat_map_arm, visit_arm}
         make_walk_flat_map!{Attribute, walk_flat_map_attribute, visit_attribute}
         make_walk_flat_map!{ExprField, walk_flat_map_expr_field, visit_expr_field}
@@ -1286,13 +1293,6 @@ pub mod visit {
         GenericArg,
     }
 
-    pub trait WalkItemKind: Sized {
-        fn walk<'a, V: Visitor<'a>>(
-            item: &'a Item<Self>,
-            visitor: &mut V,
-        ) -> V::Result;
-    }
-
     make_ast_visitor!(Visitor<'ast>);
 
     impl WalkItemKind for ItemKind {
@@ -1840,10 +1840,6 @@ pub mod mut_visit {
         }
     }
 
-    pub trait WalkItemKind: Sized {
-        fn walk(item: &mut Item<Self>, visitor: &mut impl MutVisitor);
-    }
-
     make_ast_visitor!(MutVisitor, mut);
 
     /// Use a map-style function (`FnOnce(T) -> T`) to overwrite a `&mut T`. Useful
@@ -2257,7 +2253,7 @@ pub mod mut_visit {
     }
 
     impl WalkItemKind for ItemKind {
-        fn walk(item: &mut Item<Self>, visitor: &mut impl MutVisitor) {
+        fn walk<V: MutVisitor>(item: &mut Item<Self>, visitor: &mut V) {
             let Item { attrs, id, span, vis, ident, kind, tokens } = item;
             visitor.visit_id(id);
             visit_attrs(visitor, attrs);
@@ -2498,7 +2494,7 @@ pub mod mut_visit {
 
 
     impl WalkItemKind for ForeignItemKind {
-        fn walk(item: &mut Item<Self>, visitor: &mut impl MutVisitor) {
+        fn walk<V: MutVisitor>(item: &mut Item<Self>, visitor: &mut V) {
             let Item { attrs, id, span, vis, ident, kind, tokens } = item;
             visitor.visit_id(id);
             visit_attrs(visitor, attrs);