Bug: Upgrading from 2.0.221104.6 to a later version no longer builds co_await on a DispatcherQueue

[jaimecbernardo]

Version

2.0.240111.5

Summary

After updating CppWinRT from 2.0.221104.6, which build this code, to 2.0.221117.1 or later, this code no longer builds.

I've uploaded a repository to make this easier to try to build and fail.
https://github.com/jaimecbernardo/Sample-CppWinRT-DispatcherQueue-build-regression

The code is taken from https://www.nuget.org/packages/robmikh.common/0.0.22-beta package, from this file: https://github.com/robmikh/robmikh.common/blob/aaa31a1bcd4fac19ce4c544d2cfd415612add7f0/robmikh.common/include/robmikh.common/dispatcherqueue.desktop.interop.h

CppWinRT 2.0.221104.6 builds this code. This repo can be built at this commit: jaimecbernardo/Sample-CppWinRT-DispatcherQueue-build-regression@c1a7221

The next version available (2.0.221117.1) jaimecbernardo/Sample-CppWinRT-DispatcherQueue-build-regression@7742b75 , and the lastest (2.0.221104.6) jaimecbernardo/Sample-CppWinRT-DispatcherQueue-build-regression@c1a7221 , no longer allow build this repository.

Reproducible example

#pragma once
#include <winrt/Windows.Foundation.h>
#include <winrt/Windows.System.h>
#include <dispatcherqueue.h>

// This code on a pre-compiled header file will no longer build.
inline winrt::fire_and_forget ShutdownAndThenPostQuitMessage(winrt::Windows::System::DispatcherQueueController const& controller, int exitCode)
{
    auto queue = controller.DispatcherQueue();
    co_await controller.ShutdownQueueAsync();
    co_await queue;
    PostQuitMessage(exitCode);
    co_return;
}

Expected behavior

The code should be able to build successfully.

Actual behavior

1>------ Build started: Project: TestBuildCppWinRT, Configuration: Debug x64 ------
1>pch.cpp
1>C:\prog\janeasystems\TestBuildCppWinRT\x64\Debug\Generated Files\winrt\impl\Windows.Graphics.Capture.0.h(27,12): error C3312: no callable 'await_resume' function found for type 'winrt::Windows::System::DispatcherQueue'
1>(compiling source file 'pch.cpp')
1>Done building project "TestBuildCppWinRT.vcxproj" -- FAILED.
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Additional comments

No response

[kennykerr]

This may be a change in C++/ADL rules/compliance. If you add using namespace winrt; it works.

If that's not suitable, you can use co_await winrt::resume_foreground(queue); explicitly.

[kennykerr]

cc @robmikh

[robmikh]

Ah, thanks! I used the wil version in the past as a substitute, good to know it's still there in C++/WinRT. At some point I need to update those headers, but I've been spending most of my free time using Rust.

[sylveon]

Worth pointing out that the wil version has some extra fixes that the cppwinrt one doesn't, as well as being the only one that works on WinUI 3.

[kennykerr]

but I've been spending most of my free time using Rust

Don't look back. 😏

[jaimecbernardo]

Thank you. 😄
Ended up going with the same workaround as @robmikh : robmikh/Win32CaptureSample@fc758e3