Please support Coroutines TS in C++

[Ramón García]

Hello,

Please consider supporting the Coroutines TS in GNU C++.

It is really important to make asynchronous programming usable.

Modern programs should be scalable to use the performance of multicore
processors. Stackless coroutines allow the programmer to scale to
millions of asynchronous requests. But without the primitives in the
Concurrency TS, chaining the result of an asynchronous computation to
the next step, one must program a chain of callbacks. It becomes
quickly unusable.

The promise/future, as specified in the concurrency TS, (that is, with
the function future::then for chaining a callback to the completion of
the future) make asynchronous programming somewhat more usable.
Unfortunately, almost no C++ library shipped supports future with
then.

This is an excellent explanation of the Coroutines TS:

https://www.slideshare.net/SergeyPlatonov/gor-nishanov-c-coroutines-a-negative-overhead-abstraction

Both Visual C++ 2017 and CLANG (SVN version) support the Coroutines
TS. Please consider it.

I saw that someone started an attempt at implementing it:
https://gcc.gnu.org/ml/gcc-patches/2016-03/msg00435.html but there
were no replies.