llvm-gcc-4.2/gcc/testsuite/g++.dg/abi/vbase14.C

// { dg-options "-Wabi -fabi-version=1" }

struct E1 {};
struct E2 : public E1 {}; // { dg-warning "layout" }
struct E : public E1, public E2 {}; // { dg-warning "layout|ambiguity" }
struct N : public E { virtual void f () {} };  // { dg-warning "nearly" }