From deae10e0384c3224662946bc33e3a5badff782c6 Mon Sep 17 00:00:00 2001
From: Robert Griesemer <gri@golang.org>
Date: Mon, 14 Jul 2014 19:14:27 -0700
Subject: [PATCH] go/ast: fix walk to handle "for range x"

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/117790043
---
 src/pkg/go/ast/walk.go | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/pkg/go/ast/walk.go b/src/pkg/go/ast/walk.go
index fedffb3f22f..73ac38647a2 100644
--- a/src/pkg/go/ast/walk.go
+++ b/src/pkg/go/ast/walk.go
@@ -275,7 +275,9 @@ func Walk(v Visitor, node Node) {
 		Walk(v, n.Body)
 
 	case *RangeStmt:
-		Walk(v, n.Key)
+		if n.Key != nil {
+			Walk(v, n.Key)
+		}
 		if n.Value != nil {
 			Walk(v, n.Value)
 		}