23 General utilities library [utilities]

23.14 Function objects [function.objects]

23.14.9 Bitwise operations [bitwise.operations]

23.14.9.4 Class template bit_­not [bitwise.operations.not]

template<class T = void> struct bit_not { constexpr T operator()(const T& x) const; }; constexpr T operator()(const T& x) const;
Returns: ~x.
template<> struct bit_not<void> { template<class T> constexpr auto operator()(T&& t) const -> decltype(~std::forward<T>(t)); using is_transparent = unspecified; };
template<class T> constexpr auto operator()(T&&) const -> decltype(~std::forward<T>(t));
Returns: ~std​::​forward<T>(t).