From 55edf49a015f1448a374875a89040ef71104157f Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@golang.org>
Date: Wed, 7 Oct 2009 22:19:42 -0700
Subject: [PATCH] add & fix bug207: rewritten if condition was discarding
 initialization work.

R=ken
OCL=35454
CL=35457
---
 src/cmd/gc/walk.c        | 11 +++++++++--
 test/fixedbugs/bug207.go | 23 +++++++++++++++++++++++
 2 files changed, 32 insertions(+), 2 deletions(-)
 create mode 100644 test/fixedbugs/bug207.go

diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index 53352a8e0d1..abbd37335b2 100644
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -356,7 +356,7 @@ walkstmt(Node **np)
 		walkstmtlist(n->ninit);
 		if(n->ntest != N) {
 			walkstmtlist(n->ntest->ninit);
-			walkexpr(&n->ntest, &n->ntest->ninit);
+			walkexpr(&n->ntest, &n->ninit);
 		}
 		walkstmt(&n->nincr);
 		walkstmtlist(n->nbody);
@@ -364,7 +364,7 @@ walkstmt(Node **np)
 
 	case OIF:
 		walkstmtlist(n->ninit);
-		walkexpr(&n->ntest, &n->ntest->ninit);
+		walkexpr(&n->ntest, &n->ninit);
 		walkstmtlist(n->nbody);
 		walkstmtlist(n->nelse);
 		break;
@@ -455,6 +455,13 @@ walkexpr(Node **np, NodeList **init)
 	if(n == N)
 		return;
 
+	if(init == &n->ninit) {
+		// not okay to use n->ninit when walking n,
+		// because we might replace n with some other node
+		// and would lose the init list.
+		fatal("walkexpr init == &n->ninit");
+	}
+
 	// annoying case - not typechecked
 	if(n->op == OKEY) {
 		walkexpr(&n->left, init);
diff --git a/test/fixedbugs/bug207.go b/test/fixedbugs/bug207.go
new file mode 100644
index 00000000000..5810d669011
--- /dev/null
+++ b/test/fixedbugs/bug207.go
@@ -0,0 +1,23 @@
+// $G $D/$F.go && $L $F.$A && ./$A.out
+
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// used to panic because 6g didn't generate
+// the code to fill in the ... argument to fmt.Sprint.
+
+package main
+
+import "fmt"
+
+type T struct {
+	a, b, c, d, e []int;
+}
+
+var t T
+
+func main() {
+	if fmt.Sprint("xxx", t) != "yyy" { 
+	}
+}