VS2013 Update2 FTW

[udpn]

template struct Z {};
struct B : Z {};
struct C : B, Z {};
void f(Z const &) {}
int main() { f(C()); }
Clang: ambiguous conversion from derived class 'C' to base class 'Z':
GCC: ‘Z’ is an ambiguous base of ‘C’
Visual Studio 2013: