Locating KDE Frameworks from Rust

[Ayush Singh]

Hello everyone,

I am currently working on KConfig bindings for Rust as a part of the
Season of KDE. Most of the KDE projects seem to detect and find the
location of libraries using CMake. However, finding these libraries
from non-CMake projects is not trivial. Currently, I am relying on a
hacky solution that uses the `kf5-config` binary to find the install
location of KDE frameworks.

It would be great if all the frameworks generated pkg-config by
default since it is a great language-independent way of specifying
packages. The Extra CMake Modules do contain a module
`ECMGeneratePkgConfigFile`
(https://api.kde.org/ecm/module/ECMGeneratePkgConfigFile.html#ecmgeneratepkgconfigfile)
to somewhat help with this, however, we need to list the dependencies
again which is not ideal as pointed out in the merge request I opened
(https://invent.kde.org/frameworks/kconfig/-/merge_requests/107).
There is an open issue on the CMake repository about this
(https://gitlab.kitware.com/cmake/cmake/-/issues/22621).

So I just wanted to ask others for input about generating pkg-config
files or for better ideas to detect KDE Frameworks from Rust in a
platform-independent manner since some KDE frameworks are not Linux
specific.

Ayush Singh