runtime: fix unrecovered panic on external thread

Fixes issue 8588.

LGTM=austin
R=austin
CC=golang-codereviews, khr
https://codereview.appspot.com/159700044

1 files changed, 49 insertions, 0 deletions

diff --git a/src/runtime/crash_cgo_test.go b/src/runtime/crash_cgo_test.go
index 4ff0084c2..787796558 100644
--- a/src/runtime/crash_cgo_test.go
+++ b/src/runtime/crash_cgo_test.go
@@ -8,6 +8,7 @@ package runtime_test
 
 import (
 	"runtime"
+	"strings"
 	"testing"
 )
 
@@ -34,6 +35,14 @@ func TestCgoTraceback(t *testing.T) {
 	}
 }
 
+func TestCgoExternalThreadPanic(t *testing.T) {
+	got := executeTest(t, cgoExternalThreadPanicSource, nil, "main.c", cgoExternalThreadPanicC)
+	want := "panic: BOOM"
+	if !strings.Contains(got, want) {
+		t.Fatalf("want failure containing %q. output:\n%s\n", want, got)
+	}
+}
+
 const cgoSignalDeadlockSource = `
 package main
 
@@ -117,3 +126,43 @@ func main() {
 	fmt.Printf("OK\n")
 }
 `
+
+const cgoExternalThreadPanicSource = `
+package main
+
+// void start(void);
+import "C"
+
+func main() {
+	C.start()
+	select {}
+}
+
+//export gopanic
+func gopanic() {
+	panic("BOOM")
+}
+`
+
+const cgoExternalThreadPanicC = `
+#include <stdlib.h>
+#include <stdio.h>
+#include <pthread.h>
+
+void gopanic(void);
+
+static void*
+die(void* x)
+{
+	gopanic();
+	return 0;
+}
+
+void
+start(void)
+{
+	pthread_t t;
+	if(pthread_create(&t, 0, die, 0) != 0)
+		printf("pthread_create failed\n");
+}
+`