[cmake-developers] Experiments in CMake support for Clang (header & standard) modules

[Brad King]

On 05/15/2018 03:22 AM, Stephen Kelly wrote:
> So, the answer for cmake might be that CMake can learn to extract that 
> stuff, but ignore certain cases like imports within ifdefs. 

We'd need to do the extraction from already-preprocessed sources.
This is how Fortran+Ninja+CMake works.  Unfortunately for C++
this will typically require preprocessing twice: once just to
extract module dependencies and again to actually compile.  With
Fortran we compile using the already-preprocessed source but
doing that with C++ will break things like Clang's nice handling
of macros in diagnostic messages.

-Brad