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

Subject: Re: [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: 2015-05-20 17:46:45

#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
Resolution:                        |   Keywords:
-----------------------------------+-------------------------

Comment (by leandro.gracia.gil@…):

 I don't see any either... I'll keep thinking too.

 BTW, in case somebody seeing this is wondering why we don't simply make
 foo a pure virtual in A and avoid the issue altogether, let me share a
 more meaningful example where this becomes a problem.

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

 // Let's say enabling RTTI is not an option in our platform / project.
 #define ASSIGN_CLASS_ID() virtual int GetClassId() { return __COUNTER__; }

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

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

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/11323#comment:2>
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