[Bug c++/43608] New: Boost.MPL code doesn't get the placeholders substituted anymore

["sefi at s-e-f-i dot de" <gcc-bugzilla at gcc dot gnu dot org>]

The following code stopped working with gcc-4.5.
gcc-4.4.3 and clang both accept it.
On gcc-4.5, boost::mpl_::arg<2> is passed to metafunction instead of test1.
The strange thing is: If the specialization of metafunction<_2> is provided,
the code works again.
I'm sorry that this is not a minimal test case, because I don't know how to get
rid of the MPL parts.


#include <boost/mpl/placeholders.hpp>
#include <boost/mpl/fold.hpp>
#include <boost/mpl/push_back.hpp>
#include <boost/mpl/at.hpp>
#include <boost/mpl/vector/vector10.hpp>

struct test1
{
        typedef int inner_type;
};

template<
        typename Foo
>
struct metafunction
{
        typedef typename Foo::inner_type type;
};

#if 0
template<>
struct metafunction<
        boost::mpl::_2
>;
#endif

int main()
{
        typedef boost::mpl::fold<
                boost::mpl::vector1<
                        test1
                >,
                boost::mpl::vector0<>,
                boost::mpl::push_back<
                        boost::mpl::_1,
                        metafunction<
                                boost::mpl::_2
                        >
                >
        >::type transformed;

        boost::mpl::at_c<transformed, 0>::type i = 42;
}


-- 
           Summary: Boost.MPL code doesn't get the placeholders substituted
                    anymore
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: sefi at s-e-f-i dot de


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43608