33 Concurrency support library [thread]

33.10 Futures [futures]

33.10.10 Class template packaged_­task [futures.task]

33.10.10.3 Globals [futures.task.nonmembers]

template<class R, class... ArgTypes> void swap(packaged_task<R(ArgTypes...)>& x, packaged_task<R(ArgTypes...)>& y) noexcept;
Effects: As if by x.swap(y).