From 5ff7d8489206e6080f98ba54535ada78db8e4d09 Mon Sep 17 00:00:00 2001
From: Ken Thompson <ken@golang.org>
Date: Thu, 9 Jul 2009 11:41:06 -0700
Subject: [PATCH] segment fault

R=rsc
OCL=31396
CL=31396
---
 src/cmd/gc/walk.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index 08be5bfcb4..65313bcbce 100644
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -790,6 +790,10 @@ loop:
 		if(top != Erv)
 			goto nottop;
 		walktype(n->left, Erv);
+		if(n->left == N) {
+			yyerror("missing argument to len");
+			goto ret;
+		}
 		defaultlit(n->left, T);
 		implicitstar(&n->left);
 		t = n->left->type;