--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/go.dg/mapstring.go	Thu Feb 13 11:34:05 2020 +0900
@@ -0,0 +1,11 @@
+// { dg-do compile }
+// { dg-options "-fgo-debug-optimization" }
+
+package p
+
+func F(m map[string]int, a, b []byte) int {
+	x := m[string(a)]     // { dg-error "no copy string\\(\\\[\\\]byte\\)" }
+	y, ok := m[string(b)] // { dg-error "no copy string\\(\\\[\\\]byte\\)" }
+	_ = ok
+	return x + y
+}