pkg-config pc files not created for *_threads libs

[cimes-isi]

It appears that pc files are not being created (or at least installed) for the libraries that provide thread-related functions, which makes it difficult to automatically discover if these libraries are available. PR #52 describes nicely FFTW's position on threading, but since functions like fftw[f]_threads_init are provided by the FFTW *_threads libraries, those FFTW libraries need to be discoverable, even if their pkg-config files leave the actual thread linking to the application (e.g., -lpthread).

[matteo-frigo]

I think that the right approach to this problem is to say that installing libFOO_threads.{a.so} installs a separate file FOO_threads.pc (as opposed to adding the threads library to the normal fftw3.pc file).
Does it sound reasonable?

[cimes-isi]

Yes, that is what I'd expect. FOO_threads.pc should in turn have a Requires (or perhaps Requires.private) on FOO since libFOO.{a,so} is a transitive dependency.

[samueljmcameron]

I would be interested in this feature as well, though mainly for mpi, not threading.

[antoniovazquezblanco]

I am currently dealing with this issue. It seems to get more complicated when fftw is installed via brew in a non-standard location and the compiler does not find the library by itself so meson build system needs extra configuration...

It would be awesome to see this fixed...

[antoniovazquezblanco]

A possible fix at #407