namespace std { // [bit.cast], bit_cast template<typename To, typename From> constexpr To bit_cast(const From& from) noexcept; // [bit.pow.two], integral powers of 2 template <class T> constexpr bool ispow2(T x) noexcept; template <class T> constexpr T ceil2(T x) noexcept; template <class T> constexpr T floor2(T x) noexcept; template <class T> constexpr T log2p1(T x) noexcept; }