add & fix bug207: rewritten if condition

was discarding initialization work.

R=ken
OCL=35454
CL=35457

diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index 53352a8e0d101bbb82b4d83643bef25bc787b9fb..abbd37335b2a865fa1336b2286580a7a695230f8 100644 (file)
--- 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 (file)
index 0000000..5810d66
--- /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" { 
+       }
+}