error: member access into incomplete type 'const _GUID' with clang-cl

[equeim]

When building app with clang-cl compiler, compilation fails with following error:

2022-09-04T14:46:14.7937297Z FAILED: src/CMakeFiles/tremotesf.dir/tremotesf/filemanagerlauncher_windows.cpp.obj 
2022-09-04T14:46:14.8474303Z C:\PROGRA~1\LLVM\bin\clang-cl.exe  /nologo -TP -DFMT_UNICODE=1 -DQT_ACCESSIBILITY_SUPPORT_LIB -DQT_CORE_LIB -DQT_DEPRECATED_WARNINGS -DQT_DISABLE_DEPRECATED_BEFORE=0x050e00 -DQT_EVENTDISPATCHER_SUPPORT_LIB -DQT_FONTDATABASE_SUPPORT_LIB -DQT_GUI_LIB -DQT_MESSAGELOGCONTEXT -DQT_NETWORK_LIB -DQT_STATICPLUGIN -DQT_SVG_LIB -DQT_THEME_SUPPORT_LIB -DQT_WIDGETS_LIB -DQT_WINDOWSUIAUTOMATION_SUPPORT_LIB -DTREMOTESF_APP_ID=\"org.equeim.Tremotesf\" -DTREMOTESF_APP_NAME=\"Tremotesf\" -DTREMOTESF_BUNDLED_ICONS_DIR=\"icons\" -DTREMOTESF_BUNDLED_ICON_THEME=\"breeze\" -DTREMOTESF_BUNDLED_QT_TRANSLATIONS_DIR=\"translations\" -DTREMOTESF_QT_TRANSLATIONS_FILENAME=\"qtbase\" -DTREMOTESF_VERSION=\"1.11.3\" -DWINRT_LEAN_AND_MEAN -DWINRT_NO_MODULE_LOCK -DWINVER=0x0603 -D_SILENCE_CLANG_COROUTINE_MESSAGE -D_WIN32_WINNT=0x0603 -ID:\a\tremotesf2\tremotesf2\build-Debug-clang-cl\src -ID:\a\tremotesf2\tremotesf2\src -ID:\a\tremotesf2\tremotesf2\build-Debug-clang-cl\src\tremotesf_autogen\include -ID:\a\tremotesf2\tremotesf2\vcpkg_installed\x64-windows-static\include\qt5\QtConcurrent -imsvcD:\a\tremotesf2\tremotesf2\vcpkg_installed\x64-windows-static\include\qt5 -imsvcD:\a\tremotesf2\tremotesf2\vcpkg_installed\x64-windows-static\include\qt5\QtCore -imsvcD:\a\tremotesf2\tremotesf2\vcpkg_installed\x64-windows-static\tools\qt5\mkspecs\win32-msvc -imsvcD:\a\tremotesf2\tremotesf2\vcpkg_installed\x64-windows-static\include\qt5\QtNetwork -imsvcD:\a\tremotesf2\tremotesf2\vcpkg_installed\x64-windows-static\include -imsvcD:\a\tremotesf2\tremotesf2\vcpkg_installed\x64-windows-static\include\qt5\QtWidgets -imsvcD:\a\tremotesf2\tremotesf2\vcpkg_installed\x64-windows-static\include\qt5\QtGui -imsvcD:\a\tremotesf2\tremotesf2\vcpkg_installed\x64-windows-static\include\qt5\QtEventDispatcherSupport -imsvcD:\a\tremotesf2\tremotesf2\vcpkg_installed\x64-windows-static\include\qt5\QtFontDatabaseSupport -imsvcD:\a\tremotesf2\tremotesf2\vcpkg_installed\x64-windows-static\include\qt5\QtThemeSupport -imsvcD:\a\tremotesf2\tremotesf2\vcpkg_installed\x64-windows-static\include\qt5\QtAccessibilitySupport -imsvcD:\a\tremotesf2\tremotesf2\vcpkg_installed\x64-windows-static\include\qt5\QtWindowsUIAutomationSupport -imsvcD:\a\tremotesf2\tremotesf2\vcpkg_installed\x64-windows-static\include\KF5\KWidgetsAddons -imsvcD:\a\tremotesf2\tremotesf2\vcpkg_installed\x64-windows-static\include\KF5 -imsvcD:\a\tremotesf2\tremotesf2\vcpkg_installed\x64-windows-static\include\qt5\QtSvg /DWIN32 /D_WINDOWS /EHsc /Zi /Ob0 /Od /RTC1 -MTd /W4 -std:c++17 /showIncludes /Fosrc\CMakeFiles\tremotesf.dir\tremotesf\filemanagerlauncher_windows.cpp.obj /Fdsrc\CMakeFiles\tremotesf.dir\ -c -- D:\a\tremotesf2\tremotesf2\src\tremotesf\filemanagerlauncher_windows.cpp
2022-09-04T14:46:14.9933983Z In file included from D:\a\tremotesf2\tremotesf2\src\tremotesf\filemanagerlauncher_windows.cpp:12:
2022-09-04T14:46:14.9935699Z In file included from C:\Program Files (x86)\Windows Kits\10\\include\10.0.22621.0\\cppwinrt\winrt/Windows.Foundation.h:9:
2022-09-04T14:46:15.0114235Z ##[error]C:\Program Files (x86)\Windows Kits\10\\include\10.0.22621.0\\cppwinrt\winrt/base.h(295,27): error: member access into incomplete type 'const _GUID'
2022-09-04T14:46:15.0115555Z             return { value.Data1, value.Data2, value.Data3,
2022-09-04T14:46:15.0115873Z                           ^
2022-09-04T14:46:15.0117081Z C:\Program Files (x86)\Windows Kits\10\\include\10.0.22621.0\\cppwinrt\winrt/base.h(274,59): note: in instantiation of function template specialization 'winrt::guid::convert<true, _GUID>' requested here
2022-09-04T14:46:15.0117735Z         constexpr guid(GUID const& value) noexcept : guid(convert<dummy>(value)) { }
2022-09-04T14:46:15.0118123Z                                                           ^
2022-09-04T14:46:15.0119939Z C:\Program Files (x86)\Windows Kits\10\\include\10.0.22621.0\\cppwinrt\winrt/base.h(660,23): note: in instantiation of function template specialization 'winrt::guid::guid<true>' requested here
2022-09-04T14:46:15.0120512Z     inline const guid guid_v{ __uuidof(T) };
2022-09-04T14:46:15.0120798Z                       ^

The workaround is to include <guiddef.h> before winrt headers, but it looks like winrt/base.h should be responsible for this.

[sylveon]

cppwinrt goes to great lengths to allow users to not include any Windows SDK headers (of which guiddef.h is one) but still enable interop when they are included, so including guiddef.h in winrt/base.h is not a proper fix. The code you're seeing fail works on MSVC, it seems that this was regressed by #1022?

[kennykerr]

Oh? @oldnewthing

[kennykerr]

Feel free to suggest a fix for Clang. Unfortunately we don't have any Clang validation for the CI build, so we'd have to manually validate.

[kennykerr]

Repro steps:

1. Install the latest LLVM release: https://releases.llvm.org/
2. Clone the cppwinrt repo
3. Build cppwinrt (see the readme)
4. Run build_projection.cmd
5. Build the scratch project with Clang as follows:

D:\git\cppwinrt>msbuild /m /p:Configuration=Debug,Platform=x64,Clang=1 cppwinrt.sln /t:scratch

[oldnewthing]

It's weird that clang is instantiating the guid(GUID const& value) templated constructor without a caller. Will have to go into language lawyer mode to figure out what's triggering this.