On Mon, Mar 3, 2025 at 23:53 vspefs <vsp...@protonmail.com> wrote: > By the way, what's stop us from having compiler options like > `g++ -Rgcm.cache -Rsomewhere/else/gcm.cache` to specify CMI repo path, > like `-I` > for include paths? It could be useful for projects with complex folder > structure, as build tools like Make sometimes change current working > directory, > and so we need to locate CMIs in different folders. > > The mapping between module interface unit, module name, and expected CMI > filename is still performed by the module mapper. But now when looking up > a CMI, > it goes to each repo in the list, in order, until it finds a CMI that > matches > and returns its full path. When producing a CMI, the CMI file is dumped to > the > first repo. > > Ideally, all invocations concerning modules should have `-Rgcm.cache` as > the > first CMI repo. This way, all CMI producing calls remain deterministic, and > behave same as before. > > To talk about its implementation, since GCC has already written a customed > resolver for the built-in module mapper, all we need to do is adding a > driver > option, editing the existing c++tools/resolver.cc, and implementing the > option > logic. > > This could make Make-based build systems really work. The Makefile rules > proposed in this RFC make sure CMIs are built before used, and this `-R` > flag > offers big-project-ready module lookup mechanics, if we just ignore the > multiple > CMIs problem for now :( > > This option alone, I believe, could also offer some convenience to the > general > usage of modules. > > I have yet come up with a reference implementation! It should be quick > work, > though. Please share your ideas and suggestions. > > Best regards, > vspefs
This is also a problem Fortran already solved. The -J option tells where to write .mod files, and gfortran will search for .mod files in both the -J directory as well as all -I directories. I don’t mean to sound like a broken record, but it just seems to me like there is a lot to be learned from the Fortran community.
