1 files changed, 45 insertions, 0 deletions
diff --git a/misc/cgo/test/callback.go b/misc/cgo/test/callback.go
index a7f1a3ecd..44167e6e9 100644
--- a/misc/cgo/test/callback.go
+++ b/misc/cgo/test/callback.go
@@ -10,6 +10,9 @@ void callGoFoo(void);
 void callGoStackCheck(void);
 void callPanic(void);
 void callCgoAllocate(void);
+int callGoReturnVal(void);
+int returnAfterGrow(void);
+int returnAfterGrowFromGo(void);
 */
 import "C"
 
@@ -212,6 +215,48 @@ func testAllocateFromC(t *testing.T) {
 	C.callCgoAllocate() // crashes or exits on failure
 }
 
+// Test that C code can return a value if it calls a Go function that
+// causes a stack copy.
+func testReturnAfterGrow(t *testing.T) {
+	// Use a new goroutine so that we get a small stack.
+	c := make(chan int)
+	go func() {
+		c <- int(C.returnAfterGrow())
+	}()
+	if got, want := <-c, 123456; got != want {
+		t.Errorf("got %d want %d", got, want)
+	}
+}
+
+// Test that we can return a value from Go->C->Go if the Go code
+// causes a stack copy.
+func testReturnAfterGrowFromGo(t *testing.T) {
+	// Use a new goroutine so that we get a small stack.
+	c := make(chan int)
+	go func() {
+		c <- int(C.returnAfterGrowFromGo())
+	}()
+	if got, want := <-c, 129*128/2; got != want {
+		t.Errorf("got %d want %d", got, want)
+	}
+}
+
+//export goReturnVal
+func goReturnVal() (r C.int) {
+	// Force a stack copy.
+	var f func(int) int
+	f = func(i int) int {
+		var buf [256]byte
+		use(buf[:])
+		if i == 0 {
+			return 0
+		}
+		return i + f(i-1)
+	}
+	r = C.int(f(128))
+	return
+}
+
 func testCallbackStack(t *testing.T) {
 	// Make cgo call and callback with different amount of stack stack available.
 	// We do not do any explicit checks, just ensure that it does not crash.