Enable C++ Modules TS in clang-cl

Question

I am using clang (from LLVM version 7.00) on Windows via clang-cl.

I am trying to get C++ Modules to work. I have tried the clang command line arguments -fmodules-ts and -fmodules.

I have also tried the msvc command line arguments (which work under MSVC - I am using 15.8.5) /experimental:module /module:interface (which would be the normal way for non-experimental options).

All options result in the error clang-cl.exe: warning: unknown argument ignored in clang-cl.

Anyone know if it's possible to use the C++ Modules TS under clang-cl?

Answer 1

Use option -Xclang, like this:

clang-cl -Xclang -fmodules

Answer 2

To enable C++ modules support you will need latest clang 10.0 release (suspect so), that one can be downloaded from this URL, as latest snapshot build:

https://llvm.org/builds/

With Visual studio 2019 / windows - checkout following git repository:

git clone https://github.com/NTSFka/CMakeCxxModules.git

Open folder with Visual studio 2019, from Configuration > Managed configurations

Add x64-CLang-Debug configuration, select it.

Check "Show advanced variables" and in CMAKE_C_COMPILER select

C:/Program Files/LLVM/bin/clang.exe

and from CMAKE_CXX_COMPILER select

C:/Program Files/LLVM/bin/clang++.exe

Compile program.

What I have tested by myself intellisense works, but still some text is displayed in red color (vs2019, 16.3.7), situation might change with Visual studio updates.