// Testcase for tricky synthesized op= in complex inheritance situation.// This used to test whether the virtual base was copy-assigned only once.// That feature is not required by ISO C++, so the test now only checks// whether the vbase is assigned at all.int count = 0;extern "C" int printf (const char *, ...);class A { public:  A& operator = (const A&) { count++; return *this; }};class B: virtual private A { };class C: virtual public A { };class D: public B, public C { };int main(){  D a, b;  a = b;  printf ("%d\n",count);  if (count == 0)    return 1;  return 0;}