id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
11323	is_virtual_base_of fails to build when virtual bases and their ancestors define identical virtual functions	leandro.gracia.gil@…	John Maddock	"The following code snippet fails to build in clang 6.0:

{{{
#include <iostream>
#include <boost/type_traits.hpp>

struct A { virtual void foo() {} };
struct B : public virtual A { virtual void foo() {} };
struct C : public B {};

int main() {
  std::cout << boost::is_virtual_base_of<B, C>::value << std::endl;
  return 0;
}
}}}

This is the compiler error it throws:
{{{
/usr/local/include/boost/type_traits/is_virtual_base_of.hpp:55:12: error: virtual function 'A::foo' has more than one final overrider in
      'boost_type_traits_internal_struct_X'
    struct boost_type_traits_internal_struct_X : public Derived, virtual Base 
(...)
}}}

The problem can be temporarily worked around by redefining virtual void foo() {} into boost_type_traits_internal_struct_X, but that does not scale as we would need to know and override every single virtual method that appears both in A and B."	Bugs	closed	To Be Determined	type_traits	Boost 1.57.0	Problem	fixed