[Bug c++/29438] New: Friendship problem

["pcarlini at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>]

Hi. Today, while working on libstdc++/28277 I encountered this problem, which
currently prevents me from extending the fix to ext/vstring. The below is a
rather small self-contained testcase, which current mainline does not compile
because of ambiguous overloading, whereas compilers based on the EDG front-end
accept it, in strict mode too. Is it a known issue? Thanks.

namespace __gnu_cxx
{
  template<typename _CharT, typename _Traits, typename _Alloc>
    class __sso_string_base { };

  template<typename _CharT, typename _Traits, typename _Alloc,
           template <typename, typename, typename> class _Base
           = __sso_string_base>
  class __versa_string { };
}

namespace std
{
  template<typename _CharT, typename _Traits>
    class basic_ostream;

  template<typename _CharT, typename _Traits, typename _Alloc,
           template <typename, typename, typename> class _Base>
    basic_ostream<_CharT, _Traits>&
    operator<<(basic_ostream<_CharT, _Traits>& __os,
               const __gnu_cxx::__versa_string<_CharT, _Traits,
               _Alloc, _Base>&)
    { return __os; }
}

namespace std
{
  template<typename _CharT, typename _Traits>
    class basic_ostream
    {
      template<typename _CharT2, typename _Traits2, typename _Alloc,
               template <typename, typename, typename> class _Base>
        friend basic_ostream<_CharT2, _Traits2>&
        operator<<(basic_ostream<_CharT2, _Traits2>&,
                   const __gnu_cxx::__versa_string<_CharT2, _Traits2,
                   _Alloc, _Base>&);
    };
}

int main()
{
  std::basic_ostream<char, int> bo;
  __gnu_cxx::__versa_string<char, int, int> vs;

  bo << vs;
}


-- 
           Summary: Friendship problem
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pcarlini at suse dot de


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29438