std::experimental::make_ready_future

From cppreference.com
Defined in header <experimental/future>
template < class T >
future<V /* see below */> make_ready_future(T&& value);
(1) (concurrency TS)
future<void> make_ready_future();
(2) (concurrency TS)
1) If std::decay_t<T> is std::reference_wrapper<X>, then the type V is X&, otherwise, V is std::decay_t<T>.
Creates a shared state of type V that is immediately ready, with the result constructed from std::forward<T>(value), then returns a std::experimental::future associated with that shared state.
2) Creates a shared state of type void that is immediately ready, then returns a std::experimental::future associated with that shared state.

[edit] Return value

A std::experimental::future associated with the shared state that is created.

[edit] See also

(concurrency TS)
produces a future that is ready immediately and holds the given exception
(function template)