constexpr bool operator==(const month_weekday_last& x, const month_weekday_last& y) noexcept;
template<class charT, class traits> basic_ostream<charT, traits>& operator<<(basic_ostream<charT, traits>& os, const month_weekday_last& mwdl);
return os << format(os.getloc(), STATICALLY-WIDEN<charT>("{}/{}"), mwdl.month(), mwdl.weekday_last());