runtime: when crash with panic, call user Error/String methods before freezing the world

Fixes #14432.

Change-Id: I0a92ef86de95de39217df9a664d8034ef685a906
Reviewed-on: https://go-review.googlesource.com/19792
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Minux Ma <minux@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

1 files changed, 30 insertions, 0 deletions

diff --git a/src/runtime/testdata/testprogcgo/deadlock.go b/src/runtime/testdata/testprogcgo/deadlock.go
new file mode 100644
index 0000000000..ac8855af3b
--- /dev/null
+++ b/src/runtime/testdata/testprogcgo/deadlock.go
@@ -0,0 +1,30 @@
+// Copyright 2016 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.
+
+package main
+
+/*
+char *geterror() {
+	return "cgo error";
+}
+*/
+import "C"
+import (
+	"fmt"
+)
+
+func init() {
+	register("CgoPanicDeadlock", CgoPanicDeadlock)
+}
+
+type cgoError struct{}
+
+func (cgoError) Error() string {
+	fmt.Print("") // necessary to trigger the deadlock
+	return C.GoString(C.geterror())
+}
+
+func CgoPanicDeadlock() {
+	panic(cgoError{})
+}