voidambig(){struct A {};struct B : A {};struct C : A {};struct D : B, C {};
D d;
A* ap =static_cast<B*> (&d);
D* db =static_cast<D*> (ap);// { dg-error "" }
D& dr1 =static_cast<D&> (*ap);// { dg-error "" }
A& ar =static_cast<C&> (d);
D& dr =static_cast<D&> (ar);// { dg-error "" }}