[Bug c++/57524] internal compiler error on dump translation unit

["JamesMikeDuPont at googlemail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57524

--- Comment #2 from James Michael DuPont <JamesMikeDuPont at googlemail dot com> ---
Here is a small change to work around the crash :

namespace boost {

    namespace detail { namespace variant {
        struct variant_hasher: public //boost::
    static_visitor<std::size_t> {
            template <class T>
            std::size_t operator()(T const& val) const {
          //using namespace boost;
                hash<T> hasher;
                return hasher(val);
            }
        };
    }}
}

It is the uneeded namespace usage that causes the problem.