Re: [boost] [mpl] weird error using has_xxx.hpp

From: Reece Dunn (msclrhd_at_[hidden])
Date: 2005-10-22 02:26:25

Andy Little wrote:
> Hi,
> 
>  using VC7.1...   In the following the output is 0, whereas it should be 1 .
> However commenting out either of the first 2 headers makes result correct.
> 
> Can anyone repeat this in VC7.1?
> -------------
> 
> #include <boost/mpl/modulus.hpp>
> #include <boost/mpl/apply.hpp>
> 
> #include <boost/mpl/has_xxx.hpp>
#include <iostream>
> 
> namespace my{
> 
>     template<typename T>
>     struct X{
>         typedef int tag;
>     };
>     BOOST_MPL_HAS_XXX_TRAIT_DEF(tag);
> }
> int main()
> {
>   std::cout <<  my::has_tag<my::X<int> >::value << '\n';
> }
> ---------------

I have verified the problem with msvc-7.1, msvc-8.0 and borland-5.5. The 
code doesn't produce a problem on cw-9.2.

I have verified commenting out either of the first headers on msvc-7.1 
and msvc-8.0. borland-5.5 still produces 0.

- Reece