Re: [boost] [typeof] function references and gcc 3.3.5

6 Jan 2006

      Tobias Schwinger wrote:
...
Sorry for jumping in here. But I believe that
#ifndef BOOST_NO_SFINAE
     namespace boost { namespace type_of {
       template<typename T>
       typename enable_if<is_function<T>, T &>::type
       ensure_obj(T &);
     } }
     #endif
     // verified to solve the problem with GCC 3.2.3
is a much nicer solution to the problem you describe (because it leaves 
scalability up to boost::is_function).
Unfortunately, this doesn't compile neither on gcc 3.3.x nor on gcc 3.2.3.

BTW, my solution doesn't compile on gcc 4.0:

   error: ISO C++ says that these are ambiguous, even though the worst
   conversion for the first is better than the worst conversion for the
   second: [...]

Correct fix is

namespace boost { namespace type_of {
     template<class T> T& ensure_obj(const T&);
#if defined(__GNUC__) && __GNUC__ == 3 && \
         ((__GNUC_MINOR__ == 2) || (__GNUC_MINOR__ == 3))
     template<class R, class T0> R(& ensure_obj(R(&)(T0)) )(T0);
     template<class R, class T0, class T1> R(& ensure_obj(R(&)(T0,T1)) 
)(T0,T1);
     // ...
     // ...
#endif
}}

-- 
Alexander Nasonov