runtime: add test for issue 8047.

Make sure stack copier doesn't barf on a nil defer.
Bug was fixed in https://golang.org/cl/101800043
This change just adds a test.

Fixes #8047

LGTM=dvyukov, rsc
R=dvyukov, rsc
CC=golang-codereviews
https://golang.org/cl/108840043

diff --git a/test/fixedbugs/issue8047.go b/test/fixedbugs/issue8047.go
new file mode 100644 (file)
index 0000000..fe7ada5
--- /dev/null
+++ b/test/fixedbugs/issue8047.go
@@ -0,0 +1,29 @@
+// run
+
+// Copyright 2014 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.
+
+// Issue 8047.  Stack copier shouldn't crash if there
+// is a nil defer.
+
+package main
+
+func stackit(n int) {
+       if n == 0 {
+               return
+       }
+       stackit(n - 1)
+}
+
+func main() {
+       defer func() {
+               // catch & ignore panic from nil defer below
+               err := recover()
+               if err == nil {
+                       panic("defer of nil func didn't panic")
+               }
+       }()
+       defer ((func())(nil))()
+       stackit(1000)
+}