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