id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
11717	Associate an Executor used to launch the continuation to a promise/packaged_task constructor.	viboes	viboes	"Currently 
we have `async` function that constructs futures associated to an `Executor`. 

The `then()` member function should use this executor to launch the continuation. See #11716.

But futures can also have other sources, as e.g. a `promise` or a `packaged_task`. 
This paper proposes the addition of `Executor` aware constructors for `promise<T>` and `packaged_task<R(Args)>`
so that the continuation on the associated future make use of this executor.

We propose to: 
* Add `promise<T>::promise<T>(Executor&)` Executor aware constructor.

* Add `packaged_task<R(Args...)>::packaged_task(Executor&)` Executor aware constructor.
"	Feature Requests	assigned	To Be Determined	thread	Boost 1.58.0	Problem