[logical.operations.not]
22 General utilities library [utilities]
22.10 Function objects [function.objects]
22.10.10 Logical operations [logical.operations]
22.10.10.4 Class template logical_not [logical.operations.not]
template<class T = void> struct logical_not {
constexpr bool operator()(const T& x) const;
};
constexpr bool operator()(const T& x) const;
template<> struct logical_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&& t) const
-> decltype(!std::forward<T>(t));
Returns: !std::forward<T>(t).