friend constexpr basic_mask
operator==(const basic_mask&, const basic_mask&) noexcept;
friend constexpr basic_mask
operator!=(const basic_mask&, const basic_mask&) noexcept;
friend constexpr basic_mask
operator>=(const basic_mask&, const basic_mask&) noexcept;
friend constexpr basic_mask
operator<=(const basic_mask&, const basic_mask&) noexcept;
friend constexpr basic_mask
operator>(const basic_mask&, const basic_mask&) noexcept;
friend constexpr basic_mask
operator<(const basic_mask&, const basic_mask&) noexcept;