How to install a shared C library?

[dmitry-kabanov]

It seems that scikit-build-core defines CMAKE_INSTALL_PREFIX to site-packages, that is, everything is assumed to by either Python files or Python C extensions.

However, I need to install a C library, and I cannot do it somehow, although it should go to /lib/ directly, not to /lib/pythonX.Y/site-packages,
where initial / is the root of a virtual environment.

I am trying to install the library this way:

install(TARGETS oif_dispatch DESTINATION ../..) 

and the library is just not getting installed at all, with the following lines during pip install -v:

  -- Installing: /tmp/tmp2c5eaghh/wheel/platlib/../../liboif_dispatch.so
  -- Set non-toolchain portion of runtime path of "/tmp/tmp2c5eaghh/wheel/platlib/../../liboif_dispatch.so" to ""

So, I cannot find it anywhere in the virtual environment.

Question how to write the install command, so that scikit-build-core installs the actual library? Thank you!

[LecrisUT]

The destination you are pointing to is outside the wheel directory. The current default you have is ./ is pointing to the lib64/pythonX.Y/site-packages/, so I think you want to install it there? Otherwise you can also use other installation paths like https://scikit-build-core.readthedocs.io/en/latest/guide/cmakelists.html#install-directories.

Note that as indicated in the log, the RPATHs are stripped so depending on how you want to handle it, you might want to install somewhere in your package path or otherwise you would not have a predictable path to construct your INSTALL_RPATH. You could use wheel repair tools like auditwheel to automatically fix the RPATHs, but these would have trouble doing this for pointing to dependencies within the wheel. For that I am considering adding a native wheel repair feature to take the information available during the CMake build #1009. I also want to document some common pitfalls of the dynamic libraries packaging in #1022.

[henryiii]

If you want it to go to lib, you can install to ${SKBUILD_DATA_DIR}/lib. However, there are drawbacks to this; if someone installs directly to their system Python, this will be installed into /usr/lib or /lib. On macOS, Homebrew will even start warning about non-homebrew stuff being added to its folders. It's fine if you use a venv, but not everyone does. Most packages prefer to put the libraries inside the site-packages folder, and load them from there, importlib has ways to help find stuff in site-packages. For example, pybind11 puts all of it's headers inside site-packages/pybind11, and only if you install pybind11[global] do you get the /include directory copy.

https://scikit-build-core.readthedocs.io/en/latest/guide/cmakelists.html

[dmitry-kabanov]

Thank you very much for the explanation!