Add support for compiling with Visual Studio 2019

[NN---]

AppVeyor has VS 2019

[lewissbaker]

See #125 for changes needed to support vs2019 on appveyor.

I have not yet merged it because vs2019 was failing some optimised tests.
I haven't had a chance to investigate the cause of these crashes (not sure if it's exposing a bug in cppcoro or a bug in msvc).

[NN---]

There are known bugs with coroutines in MSVC with optimizations enabled.
Unfortunately I couldn't reproduce them in a way that I can give a sample project to MS.
If you have a consistent reproduction, you should ask MS to check it, and then they will fix.

[NN---]

See this: https://developercommunity.visualstudio.com/content/problem/498874/co-await-optimization-bugs-in-visual-studio-2019-r.html?childToView=716966#comment-716966
You should try again when 16.4 will be released to AppVeyor.

[joemmett]

Hi - I'm a developer on the MSVC team and am working on finishing the coroutine support in VS 2019. We've recently harnessed cppcoro as part of our internal testing of the toolchain and are internally tracking bugs related to the optimized test failures, but are running all the others regularly. I also have a small number of patches to submit to address some issues due to STL header reorganization that I hope to get into a PR soon.

[lewissbaker]

@joemmett I've updated the PR to rebuild with the latest Visual Studio 2019 on AppVeyor (MSVC 14.24.28314).

Compilation seems to be failing with odd front-end error messages:
https://ci.appveyor.com/project/lewissbaker/cppcoro/builds/30413745/job/1wf0ccttb8tegami#L35

Is MSVC getting getting confused by the use of captures within an immediately invoked coroutine lambda?

[NN---]

You can try /experimental:newLambdaProcessor

[joemmett]

@lewissbaker Sort of - that was a bug with resolving certain names within a lambda, it doesn't necessarily need to be immediately invoked. It's specific to using /std:c++latest, but can be worked around by either using the switch suggested by @NN--- or, even better, /permissive-. I do recommend using /permissive- when you can.

I tried reproducing this merge locally and adding /permissive-. I get a good build and all tests pass except two that I also saw last week:

1. A runtime crash in one of the async_auto_reset_event_tests in optimized x64 builds. This looks to be intermittent and I'm not sure if it's a codegen bug or some timing/race issue, but I've opened a bug against the back-end group for investigation.
2. x86 optimized builds are failing the 'cancel read' test because the operation_cancelled exception is not being caught by the catch handler. I've filed this with the back-end group.

[lewissbaker]

Thanks @joemmett. I've updated the build config to add /permissive- and the CI builds seem to be getting farther now.

I'm still seeing the x86 optimised tests crash (I assume this is the issue you describe).

It's possible that the async_auto_reset_event_tests could be crashing because of a race condition in the static_thread_pool implementation that I've occasionally seen (e.g. see #114). Or it could be unrelated...

[tnovotny]

Any progress on this?

[NN---]

VS 2019 16.5 fixed issues with generators and lambda.
We have encountered them in our project too, but now we don’t see any issue.
Please try the latest version.

[NN---]

VS 2019 16.5 fixed issues with generators and lambda.
We have encountered them in our project too, but now we don’t see any issue.
Please try the latest version. #

[tnovotny]

I tried building the vs2019 branch with 16.5.4 and it did not build. I mainly get these two errors.

D:\work\externals\cppcoro\lib\cancellation_state.cpp(82): error C2220: the following warning is treated as an error
D:\work\externals\cppcoro\lib\cancellation_state.cpp(82): warning C4996: 'std::atomic_init': warning STL4028: std::atomic_init() overloads are deprecated in C++20. The constructors of std::atomic provide equivalent functionality. You can define _SILENCE_CXX20_ATOMIC_INIT_DEPRECATION_WARNING or _SILENCE_ALL_CXX20_DEPRECATION_WARNINGS to acknowledge that you have received this warning.

D:\work\externals\cppcoro\test\doctest\doctest.h(3552): error C2039: 'uncaught_exception': is not a member of 'std'
C:\Program Files (x86)\Microsoft Visual Studio\2019\Preview\VC\Tools\MSVC\14.26.28801\include\map(25): note: see declaration of 'std'

Just noticed it seems to pick up the Preview, maybe that is part of the problem?

I also tried building master, but cake did not do anything there.

D:\work\externals\cppcoro>cake
python: can't open file '...\cppcoro\tools\cake\src\run.py': [Errno 2] No such file or directory