2 files changed, 16 insertions, 10 deletions

diff --git a/xtask/src/ast_src.rs b/xtask/src/ast_src.rs
index 56e3f4b0a..c7087a14e 100644
--- a/xtask/src/ast_src.rs
+++ b/xtask/src/ast_src.rs
@@ -103,8 +103,8 @@ pub(crate) const KINDS_SRC: KindsSrc = KindsSrc {
         "USE",
         "STATIC",
         "CONST",
-        "TRAIT_DEF",
-        "IMPL_DEF",
+        "TRAIT",
+        "IMPL",
         "TYPE_ALIAS",
         "MACRO_CALL",
         "TOKEN_TREE",
diff --git a/xtask/src/codegen/rust.ungram b/xtask/src/codegen/rust.ungram
index ef7c3e50e..cda0e8fbb 100644
--- a/xtask/src/codegen/rust.ungram
+++ b/xtask/src/codegen/rust.ungram
@@ -9,12 +9,12 @@ Item =
 | ExternBlock
 | ExternCrate
 | Fn
-| ImplDef
+| Impl
 | MacroCall
 | Module
 | Static
 | Struct
-| TraitDef
+| Trait
 | TypeAlias
 | Union
 | Use
@@ -66,8 +66,11 @@ SelfParam =
   )
 
 Param =
-  Attr* Pat (':' ascribed_type:TypeRef)
-| '...'
+  Attr* (
+    Pat (':' ascribed_type:TypeRef)
+  | ascribed_type:TypeRef
+  | '...'
+  )
 
 RetType =
   '->' TypeRef
@@ -120,7 +123,7 @@ Static =
   Attr* Visibility? 'static'? 'mut'? Name ':' ascribed_type:TypeRef
   '=' body:Expr ';'
 
-TraitDef =
+Trait =
   Attr* Visibility? 'unsafe'? 'auto'? 'trait' Name GenericParamList
   (':' TypeBoundList?)? WhereClause
   AssocItemList
@@ -128,9 +131,12 @@ TraitDef =
 AssocItemList =
   '{' AssocItem* '}'
 
-ImplDef =
- Attr* Visibility? 'const'? 'default'? 'unsafe'? 'impl' GenericParamList? '!'? 'for'
- WhereClause?
+Impl =
+ Attr* Visibility?
+ 'default'? 'unsafe'? 'impl' 'const'? GenericParamList? (
+   TypeRef
+ | '!'? TypeRef 'for' TypeRef
+ ) WhereClause?
  AssocItemList
 
 ParenType =