Consuming the STL module with CMake

[Zingam]

https://learn.microsoft.com/en-us/cpp/build/reference/c-cpp-prop-page?view=msvc-170#build-iso-c23-standard-library-modules
https://learn.microsoft.com/en-us/cpp/cpp/tutorial-import-stl-named-module?view=msvc-170

It seems that consuming the STL module form CMake isn't something out-of-the-box?
What would I need to do to setup a CMake project with CMakePresets to be able to consume the STL module and this should happen crossplatform with Clang/GCC?

[StephanTLavavej]

We've heard that Kitware is working on making this work out-of-the-box with CMake, but we can't share any ETA at this time.

[fsb4000]

@Zingam

Have you seen this: #3195 (comment) ?

[davidhunter22]

using import std; seems to work fine with Visual Studio solution/projects generated from CMake.
You do need to set the CXX_SCAN_FOR_MODULES property to true in your CMake. this controls the ScanSourceForModuleDependencies property in the generated .vcxproj files.
As of right now the .vcxproj generation is a bit of a mess, see https://gitlab.kitware.com/cmake/cmake/-/issues/25806, but it does work.
Note you can't control the related BuildStlModules MSBuild property directly from CMake, although quite why that property exists is a bit of a mystery to me!