winrt headers no longer compile after upgrading to g++ 15

[CarterLi]

Description / Steps to reproduce the issue

zhang@MSIGE76 ~> cat winrt.cpp
#include <winrt/Windows.Foundation.h>
zhang@MSIGE76 ~> g++ winrt.cpp -std=c++20
In file included from winrt.cpp:1:
C:/msys64/ucrt64/include/winrt/Windows.Foundation.h: In member function 'winrt::Windows::Foundation::IAsyncAction winrt::deferrable_event_args<D>::wait_for_deferrals()':
C:/msys64/ucrt64/include/winrt/Windows.Foundation.h:3313:43: error: non-template type 'coroutine_handle' used as a template [-Wtemplate-body]
 3313 |             co_await awaitable{ {}, *this };
      |                                           ^
C:/msys64/ucrt64/include/winrt/Windows.Foundation.h:3313:13: error: cannot instantiate a 'coroutine handle' for promise type 'voi' [-Wtemplate-body]
 3313 |             co_await awaitable{ {}, *this };
      |             ^~~~~~~~
zhang@MSIGE76 ~ [1]> g++ --version
g++.exe (Rev2, Built by MSYS2 project) 15.1.0
Copyright (C) 2025 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

zhang@MSIGE76 ~> which g++
/ucrt64/bin/g++

Expected behavior

It compiles successfully

Actual behavior

Errored out

Verification

• I have verified that my MSYS2 is up-to-date before submitting the report (see https://www.msys2.org/docs/updating/)

Windows Version

MINGW64_NT-10.0-26120

MINGW environments affected

• MINGW64
• MINGW32
• UCRT64
• CLANG64
• CLANGARM64

Are you willing to submit a PR?

No response

[CarterLi]

It breaks fastfetch. I can confirm it still compiles with clang

[lazka]

thanks

[Biswa96]

This similar issue causes build failure in kdeconnet in ucrt64.

[oltolm]

There is no Windows.Foundation.h in C:/msys64/ucrt64/include/winrt. My Windows.Foundation.h is in C:\msys64\ucrt64\include\windows.foundation.h and I can not reproduce this problem.

You need to install the cppwinrt package to reproduce it.

[CarterLi]

There is no Windows.Foundation.h in C:/msys64/ucrt64/include/winrt. My Windows.Foundation.h is in C:\msys64\ucrt64\include\windows.foundation.h and I can not reproduce this problem.

You need to install the cppwinrt package to reproduce it.

zhang@MSIGE76 ~/f/build (dev)> pacman -Qo /clang64/include/windows.foundation.h
/clang64/include/windows.foundation.h is owned by mingw-w64-clang-x86_64-headers-git 12.0.0.r688.g6b2176247-1
zhang@MSIGE76 ~/f/build (dev)> pacman -Qo /clang64/include/winrt/windows.foundation.h
/clang64/include/winrt/windows.foundation.h is owned by mingw-w64-clang-x86_64-cppwinrt 2.0.240405.15-1

All winrt headers are in folder winrt/. windows.foundation.h and winrt/Windows.Foundation.h are different header files.

[ClassicOldSong]

The minimal code to reproduce is:

#include <winrt/Windows.Foundation.h>

Put it in test.cpp, run g++ -std=c++20 test.cpp

BOOM

(just notice it's the same as OP lol

[Biswa96]

• I have reported the issue in upstream Bug: compiler error with gcc 15 and coroutine in windows.foundation.h microsoft/cppwinrt#1490

[Biswa96]

The related gcc issue is https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120495