go/*: permit "for range x"

LGTM=rsc
R=rsc
CC=golang-codereviews
https://codereview.appspot.com/112970044

1 files changed, 3 insertions, 3 deletions

diff --git a/src/pkg/go/ast/ast.go b/src/pkg/go/ast/ast.go
index 6e635cd01..312e3d1b9 100644
--- a/src/pkg/go/ast/ast.go
+++ b/src/pkg/go/ast/ast.go
@@ -699,9 +699,9 @@ type (
 	// A RangeStmt represents a for statement with a range clause.
 	RangeStmt struct {
 		For        token.Pos   // position of "for" keyword
-		Key, Value Expr        // Value may be nil
-		TokPos     token.Pos   // position of Tok
-		Tok        token.Token // ASSIGN, DEFINE
+		Key, Value Expr        // Key, Value may be nil
+		TokPos     token.Pos   // position of Tok; invalid if Key == nil
+		Tok        token.Token // ILLEGAL if Key == nil, ASSIGN, DEFINE
 		X          Expr        // value to range over
 		Body       *BlockStmt
 	}