3 files changed, 22 insertions, 10 deletions

diff --git a/xtask/src/ast_src.rs b/xtask/src/ast_src.rs
index 38b60b2a5..427406249 100644
--- a/xtask/src/ast_src.rs
+++ b/xtask/src/ast_src.rs
@@ -144,7 +144,7 @@ pub(crate) const KINDS_SRC: KindsSrc = KindsSrc {
         "ARRAY_EXPR",
         "PAREN_EXPR",
         "PATH_EXPR",
-        "LAMBDA_EXPR",
+        "CLOSURE_EXPR",
         "IF_EXPR",
         "WHILE_EXPR",
         "CONDITION",
diff --git a/xtask/src/codegen/gen_syntax.rs b/xtask/src/codegen/gen_syntax.rs
index 90f746e96..059538696 100644
--- a/xtask/src/codegen/gen_syntax.rs
+++ b/xtask/src/codegen/gen_syntax.rs
@@ -579,7 +579,19 @@ fn lower_rule(acc: &mut Vec<Field>, grammar: &Grammar, label: Option<&String>, r
         }
         Rule::Labeled { label: l, rule } => {
             assert!(label.is_none());
-            if l == "op" {
+            let manually_implemented = matches!(
+                l.as_str(),
+                "lhs"
+                    | "rhs"
+                    | "then_branch"
+                    | "else_branch"
+                    | "start"
+                    | "end"
+                    | "op"
+                    | "index"
+                    | "base"
+            );
+            if manually_implemented {
                 return;
             }
             lower_rule(acc, grammar, Some(l), rule);
diff --git a/xtask/src/codegen/rust.ungram b/xtask/src/codegen/rust.ungram
index 93195befe..aef07cb1e 100644
--- a/xtask/src/codegen/rust.ungram
+++ b/xtask/src/codegen/rust.ungram
@@ -222,7 +222,7 @@ Expr =
 | IfExpr
 | IndexExpr
 | Label
-| LambdaExpr
+| ClosureExpr
 | Literal
 | LoopExpr
 | MacroCall
@@ -266,14 +266,14 @@ PrefixExpr =
 
 BinExpr =
   Attr*
-  Expr
+  lhs:Expr
   op:(
     '||' | '&&'
     | '==' | '!=' | '<=' | '>=' | '<' | '>'
     | '+' | '*' | '-' | '/' | '%' | '<<' | '>>' | '^' | '|' | '&'
     | '=' | '+=' | '/=' | '*=' | '%=' | '>>=' | '<<=' | '-=' | '|=' | '&=' | '^='
   )
-  Expr
+  rhs:Expr
 
 CastExpr =
   Attr* Expr 'as' Type
@@ -288,7 +288,7 @@ ArrayExpr =
   ) ']'
 
 IndexExpr =
-  Attr* Expr '[' Expr ']'
+  Attr* base:Expr '[' index:Expr ']'
 
 TupleExpr =
   Attr* '(' Attr* (Expr (',' Expr)* ','?)? ')'
@@ -318,13 +318,13 @@ MethodCallExpr =
 FieldExpr =
   Attr* Expr '.' NameRef
 
-LambdaExpr =
+ClosureExpr =
   Attr* 'static'? 'async'? 'move'?  ParamList RetType?
   body:Expr
 
 IfExpr =
-  Attr* 'if' Condition BlockExpr
-  ('else' (IfExpr | BlockExpr))?
+  Attr* 'if' Condition then_branch:BlockExpr
+  ('else' else_branch:(IfExpr | BlockExpr))?
 
 Condition =
   'let' Pat '=' Expr
@@ -352,7 +352,7 @@ ContinueExpr =
   Attr* 'continue' 'lifetime'?
 
 RangeExpr =
-  Attr* Expr? op:('..' | '..=') Expr?
+  Attr* start:Expr? op:('..' | '..=') end:Expr?
 
 MatchExpr =
   Attr* 'match' Expr MatchArmList