Force qtbase to build with C++20

[mntt-SSE]

Hi! Is there any way to force vcpkg to build qtbase with C++20?

The reason I want to do this is my Windows application is built with C++20, and I get linker errors (LNK2038: mismatch detected for '_COROUTINE_ABI': value '1' doesn't match value '2' ) when building Qt with the default C++17.

I've previously built Qt manually using their configure.bat build script like this:

call ..\configure.bat^
	-prefix "%qt_install_dir%"^
	-static^
	-static-runtime^
	-nomake tests^
	-nomake examples^
	-platform win32-msvc^
	-c++std c++20^
	-debug-and-release

which works, but I'm trying to move the dependency handling to vcpkg and I'd like to avoid writing my own port.

Any suggestions welcome! The application I'm building is part of a big monolith codebase, so it's not necessarily simple to just switch to C++17, or encapsulate the Qt code.

[Osyotr]

Try something like this in your custom triplet:

list(APPEND VCPKG_CMAKE_CONFIGURE_OPTIONS "-DCMAKE_CXX_STANDARD=20")

https://learn.microsoft.com/en-us/vcpkg/users/triplets#vcpkg_cmake_configure_options

[mntt-SSE]

Thanks for the answer! Adding -DCMAKE_CXX_STANDARD=20 did not work. However, I was able to solve it by adding -DFEATURE_cxx20=ON to my triplet:

if(PORT MATCHES "qtbase")
	list(APPEND VCPKG_CMAKE_CONFIGURE_OPTIONS "-DFEATURE_cxx20=ON")
endif()