17 Language support library [language.support]

17.12 Coroutines [support.coroutine]

17.12.3 Class template coroutine_­handle [coroutine.handle]

17.12.3.5 Promise access [coroutine.handle.promise]

Promise& promise() const;
Requires: *this refers to a coroutine.
Returns: A reference to the promise of the coroutine.