Allow LightGBM to be easily used in external projects via modern CMake style with find_package and target_link_libraries

[nims11]

Summary

Generate pkg-config file for the library.

Motivation

pkg-config is a widely used way to provide linker flags and include directories for use in other projects. For example, with cmake, a project can just call find_package(LightGBM REQUIRED) and it will set the include directories and linker flags.

Note this applies to use cases when precompiled lightgbm is installed in a system/container. This doesn't apply to projects building with lightgbm with add_subdirectory.

Description

Generate a .pc file as part of the build.

References

https://people.freedesktop.org/~dbn/pkg-config-guide.html

[jameslamb]

Thanks very much for your interest in LightGBM! The guide you attached looks helpful.

Could you point to a project that you use that has pkg-config support, so that anyone picking up this feature could look at the code there as a reference?

[nims11]

zlib has pkg-config support. They do this by having a zlib.pc.cmakein template which is used to generate the pc file during build (relevant CMakelists.txt lines). Afaik, this is a common way of adding pkg-config support.

I will also be happy to contribute if you think it is worth having.

[StrikerRUS]

For example, with cmake, a project can just call find_package(LightGBM REQUIRED) and it will set the include directories and linker flags.

For the reference, see how huge refactoring was required for XGBoost to achieve this goal: dmlc/xgboost#4323 (comment).

To be honest, I'm quite sceptical about that pkg-config will do all the magic for us.

[StrikerRUS]

Closed in favor of being in #2302. We decided to keep all feature requests in one place.

Welcome to contribute this feature! Please re-open this issue (or post a comment if you are not a topic starter) if you are actively working on implementing this feature.

[StrikerRUS]

Also, for pkg-config example refer to dmlc/xgboost#5744.