--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/cpp0x/anon-union1.C	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,27 @@
+// PR c++/66583
+// { dg-do run { target c++11 } }
+
+template <class T>
+T&& move(T& t) { return static_cast<T&&>(t); }
+
+struct A {
+  A() { };
+  A(const A&) { }
+};
+
+struct B {
+  union {
+    int m_1 = 0;
+    int m_2;
+  };
+  A dummy;
+};
+
+int main()
+{
+  B b;
+  b.m_1 = 1;
+  B c = move(b);
+  if (c.m_1 != 1)
+    __builtin_abort();
+}