[Boost-bugs] [Boost C++ Libraries] #11323: is_virtual_base_of fails to build when virtual bases and their ancestors define identical virtual functions

Subject: [Boost-bugs] [Boost C++ Libraries] #11323: is_virtual_base_of fails to build when virtual bases and their ancestors define identical virtual functions
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2015-05-19 17:36:07

#11323: is_virtual_base_of fails to build when virtual bases and their ancestors
define identical virtual functions
----------------------------------+-------------------------
 Reporter:  leandro.gracia.gil@…  |      Owner:  johnmaddock
     Type:  Bugs                  |     Status:  new
Milestone:  To Be Determined      |  Component:  type_traits
  Version:  Boost 1.57.0          |   Severity:  Problem
 Keywords:                        |
----------------------------------+-------------------------
 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.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/11323>
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