RE: [boost] tuples changes

From: John Maddock (John_Maddock_at_[hidden])
Date: 2002-01-14 07:19:10

>There were very few compiler fixes after Beta2, so it's probably not
>fixed.  If you send me a testcase, I'll look for a fix (and I'll make
>sure newer compilers don't ICE.)

The test case is quite small:

#include <boost/type_traits.hpp>

namespace boost{

    template<int N, typename Tuple>
    struct element
    {
    };

      template<int N, typename Tuple>
      struct element_ref
      {
      private:
        typedef element<N, Tuple> e_type;
        typedef typename e_type::RET elt_type;
        typedef add_reference<elt_type> ar_t;

      public:
        typedef typename ar_t::type RET;
        typedef RET type;
      };

}

int main(){ return 0; }

Interestingly the following program also fails, note that now we only
forward declare boost::add_reference, the code should still compile, but
fails to do so, with a complaint about add_reference being incomplete.  It
looks to me that the compiler is trying to semi-instantiate a template that
should never in fact be instantiated.

namespace boost{

template <class T>
struct add_reference;

template<int N, typename Tuple>
struct element;

template<int N, typename Tuple>
struct element_ref
{
private:
  typedef element<N, Tuple> e_type;
  typedef typename e_type::RET elt_type;
  typedef add_reference<elt_type> ar_t;

public:
  typedef typename ar_t::type RET;
  typedef RET type;
};

}

int main(){ return 0; }

- John Maddock
http://ourworld.compuserve.com/homepages/john_maddock/