RFC: A redesign of `-Mmodules` output

[vspefs]

On Wednesday, March 5th, 2025 at 21:06, Nathaniel Shead via Gcc <gcc@gcc.gnu.org> wrote:

> Worth noting that GCC already provides a mapper that you can customise:
> 
> $ g++ -fmodules -fmodule-mapper='|@g++-module-server -r path' -c m.cpp
> 
> for an m.cpp that provides a module "M" will write to 'path/M.gcm'.

Exactly! I have found that as well. I had always thought that the whole default
module mapper is embedded in GCC source, but when I started to look into that
I immediately found the standalone `g++-module-server` executable.

I'll implement this `-R` thing there, and try to have Autotools working with
modules in this way. We'll see how things roll out.