20 General utilities library [utilities]

20.14 Function objects [function.objects]

20.14.5 Class template reference_­wrapper [refwrap]

20.14.5.4 Invocation [refwrap.invoke]

template<class... ArgTypes> invoke_result_t<T&, ArgTypes...> operator()(ArgTypes&&... args) const;
Mandates: T is a complete type.
Returns: INVOKE(get(), std::forward<ArgTypes>(args)...).