id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
3226	boost::fusion sequence fails to work in boost::mpl::fold	Jeffrey Hellrung <jhellrung@…>		"The following results in a compiler error (boost 1.39, MSVC 9) at the line where boost::mpl::fold is applied to fusion_vector_type.  Commenting this line out makes the code compile.

{{{

#include <boost/fusion/container/vector.hpp>
#include <boost/mpl/assert.hpp>
#include <boost/mpl/fold.hpp>
#include <boost/mpl/placeholders.hpp>
#include <boost/mpl/vector.hpp>
#include <boost/type_traits/is_void.hpp>

int main(int argc, char* argv[])
{
    typedef boost::fusion::vector< int > fusion_vector_type;
    typedef boost::mpl::vector< int > mpl_vector_type;
    typedef boost::mpl::fold< fusion_vector_type, void, boost::mpl::_1 >::type void1_type;
    typedef boost::mpl::fold< mpl_vector_type, void, boost::mpl::_1 >::type void2_type;
    BOOST_MPL_ASSERT((boost::is_void< void2_type >));
    return 0;
}

}}}

Is this a problem with boost::fusion::vector failing some requirement of being a boost::mpl sequence, or of boost::mpl::fold using something outside the stated requirements of boost::mpl sequences?

I've attached the compiler output.

- Jeff"	Bugs	closed	Boost 1.40.0	fusion	Boost 1.39.0	Problem	invalid