I have a git repository containing interface definitions (protobuf files) that is imported as a submodule from a lot of other projects. The interface definitions are inside subdirectories.
I'd now like to add the necessary infrastructure to the interface definition project to make it usable as a Meson subproject.
Ideally, the client projects would define a generator to process the protobuf files, and I'd then pass the subproject handle into the generator, which calls the protobuf compiler once for each input file, with the other input files available in the same directory for import statements.
Because the clients use different programming languages and have differing constraints, it does not make sense for me to do the protobuf processing as part of the interface definition project.
So what I'm essentially looking for is a passthrough -- similar to the _DATA primitive in automake -- that just takes the input file verbatim and adds it to the list of output files, keeping subdirectory information intact.