want := "found pointer to free object"
	if !strings.Contains(got, want) {
		t.Fatalf("expected %q in output, but got %q", want, got)
	}
}

func TestGCTestMoveStackOnNextCall(t *testing.T) {
	t.Parallel()
	var onStack int
	// GCTestMoveStackOnNextCall can fail in rare cases if there's
	// a preemption. This won't happen many times in quick
	// succession, so just retry a few times.