When building against a static plugin, you need to have explicit dependencies that it uses as those are not stored in the .a file. With libtool, those are store in a ".la" files. Meson does not use .la files adn prefers to use pkgconfig files for this, so it need to provide the same information in the Libs.private/Requires.private sections.

Therefore, we need to generate a .pc file for every single plugin in GStreamer to know what external libraries it should be compiled against.


Afaik, this should be a meson feature, so I also filed it upstream:
https://github.com/mesonbuild/meson/issues/2772