reflect lhs typename

#include <iostream>
#include <ostream>
#include <string>
#include <type_traits>

#include <cstdlib>

struct reflect
{

    template< typename T >
    operator T () const
    {
        static_assert(std::is_default_constructible< T >{});
        typename_ = __PRETTY_FUNCTION__;
        return {};
    }

    friend
    std::ostream &
    operator << (std::ostream & _out, reflect const & _reflect)
    {
        return _out << _reflect.typename_;
    }

private :

    mutable std::string typename_;

};

int
main()
{
    reflect const r{};
    struct {} _ = r;
    std::cout << r << std::endl;
    return EXIT_SUCCESS;
}