Excluding 3rd party C++ deps (such as Eigen) from python packages

[phaedon]

We have a project which wraps some C++ libraries using pybind11 and then packages them in a wheel for installation, locally or in a Docker image.

I'm trying to migrate our old setup.py configs to scikit_build_core
However, I see that a large number of 3rd party deps (primarily Eigen) are getting packaged and installed into the wheel.

Note that we are pulling in these deps using CMake's FetchContent_Declare and FetchContent_MakeAvailable. The default then is to pull them all into the build-*/_deps/ subdir. However, when I run the build from the python command below, they are apparently fetched into some temporary build directory, from which they are "installed" into a platlib directory such as /tmp/tmpu3ectkwi/wheel/platlib/include/eigen3/unsupported/

In this excerpt, is there something I'm doing wrong with my configuration? I've studied the example at https://github.com/pybind/scikit_build_example but this is quite minimal and doesn't address the question of third-party libraries.

[tool.scikit-build]
cmake.source-dir = "../.."
build.targets = ["our_pybind_cmake_target"]
build.verbose = true
sdist.cmake = true
wheel.cmake = true
wheel.packages = ["our_package_name"]
wheel.exclude = ["**/include/**", "wheel/platlib/**"]

Am running this from the command line as follows:
python -m build --wheel --sdist --verbose

[henryiii]

You can set the build-dir to control where the build directory is, otherwise it's a temp dir. For the installation, if you want the files, you can set the wheel.install-dir, but I assume you don't wan them installed (since you just need them when building), in which case the best option is to use components. Add a component, like "python", to your installs, then request only that component be installed with install.components = ["python"].

[phaedon]

Thanks for the quick reply. I tried using build-dir to make the directory persistent in the case of "pip install"; however, this doesn't resolve the problem which is also evident when running "python -m build" as described in my question from yesterday.

The problem seems to be: even if nothing changes in my code, and I run and then immediately re-run the following

python -m build --wheel --sdist --verbose
python -m build --wheel --sdist --verbose

CMake will go through the entire configuration, fetch deps, and build process, not only once but twice each time (once for --wheel and once for --sdist). At ~90 seconds for each, the two commands above take 6 minutes in total.

This is despite CMake acknowledging that some sort of cache is available:
loading initial cache file build_scikit/CMakeInit.txt

and my verifying that the 7 external deps and their 21 directories in build_scikit/_deps/<libname>-{build,src,subbuild} are right there.

Is there a flag either on the scikit-build or on the cmake side that says, only fetch and build the artifacts that have changed on disk since the last build? I'm coming from the Bazel world, which has this as a core built-in feature, so I would appreciate understanding this better.