[ccache] clang modules (-fmodules) support

[Piotr Wach]

Hello,

we experiment with clang modules in quite large C++ code base to improve
build times.

I have seen that "-fmodules" compiler flag has been recently marked as
"hard" / unsupported (?) - is this because no one had time to implement it
or are there real problems with supporting it in ccache?

I want to try to add support for clang modules to ccache. However, I first
would like to know if someone has already tried, and it turned out to be
not possible and what were the problems with doing it.


Piotr Wach