fmt::formatter<R, Char>

template<
    typename R,
    typename Char>
requires conjunction<
        bool_constant<
            range_format_kind<R, Char>::value != range_format::disabled &&
            range_format_kind<R, Char>::value != range_format::map &&
            range_format_kind<R, Char>::value != range_format::string &&
            range_format_kind<R, Char>::value != range_format::debug_string>,
        detail::is_formattable_delayed<R, Char>>::value
struct formatter<R, Char>;