[boost] [fusion] inconsistency in size metafunction

Subject: [boost] [fusion] inconsistency in size metafunction
From: Jean-Louis Leroy (jl_at_[hidden])
Date: 2009-09-27 09:25:20

Consider :

#include <boost/fusion/include/vector.hpp>
#include <boost/fusion/include/push_back.hpp>
#include <boost/fusion/include/size.hpp>
#include <boost/mpl/assert.hpp>
#include <boost/type_traits/is_same.hpp>

int main() {
   using namespace boost;
   using namespace fusion;
   typedef vector<int, int> seq1;
   typedef result_of::push_back<vector<int>, int>::type seq2;
   BOOST_MPL_ASSERT((is_same<result_of::size<seq1>::type, 
result_of::size<seq2>::type>));
}

One would not expect this to fail, however it does :

'boost::mpl::assertion_failed' : cannot convert parameter 1 from 
'boost::mpl::failed ************boost::is_same<T,U>::* ***********' to 
'boost::mpl::assert<false>::type'
1>        with
1>        [
1>            T=boost::mpl::int_<2>,
1>            U=boost::mpl::integral_c<int,2>
1>        ]

J-L