Moving to Meson

SciPy is moving to Meson for its 1.9.0 release, planned for July 2022. During this process, any remaining issues with Meson’s Python support and achieving feature parity with numpy.distutils will be resolved. Note: parity means a large superset, but right now some BLAS/LAPACK support is missing and there are a few open issues related to Cython. SciPy uses almost all functionality that numpy.distutils offers, so if SciPy has successfully made a release with Meson as the build system, there should be no blockers left to migrate, and SciPy will be a good reference for other packages who are migrating. For more details about the SciPy migration, see:

• RFC: switch to Meson as a build system
• Tracking issue for Meson support

NumPy itself will very likely migrate to Meson as well, once the SciPy migration is done.

Moving to CMake / scikit-build

See the scikit-build documentation for how to use scikit-build. Please note that as of Feb 2022, scikit-build still relies on setuptools, so it’s probably not quite ready yet for a post-distutils world. How quickly this changes depends on funding, the current (Feb 2022) estimate is that if funding arrives then a viable numpy.distutils replacement will be ready at the end of 2022, and a very polished replacement mid-2023. For more details on this, see this blog post by Henry Schreiner.

Moving to setuptools

For projects that only use numpy.distutils for historical reasons, and do not actually use features beyond those that setuptools also supports, moving to setuptools is likely the solution which costs the least effort. To assess that, there are the numpy.distutils features that are not present in setuptools:

• Nested setup.py files
• Fortran build support
• BLAS/LAPACK library support (OpenBLAS, MKL, ATLAS, Netlib LAPACK/BLAS, BLIS, 64-bit ILP interface, etc.)
• Support for a few other scientific libraries, like FFTW and UMFPACK
• Better MinGW support
• Per-compiler build flag customization (e.g. -O3 and SSE2 flags are default)
• a simple user build config system, see [site.cfg.example](https://github.com/numpy/numpy/blob/master/site.cfg.example)
• SIMD intrinsics support

The most widely used feature is nested setup.py files. This feature will likely be ported to setuptools (see gh-18588 for status). Projects only using that feature could move to setuptools after that is done. In case a project uses only a couple of setup.py files, it also could make sense to simply aggregate all the content of those files into a single setup.py file and then move to setuptools. This involves dropping all Configuration instances, and using Extension instead. E.g.,:

from distutils.core import setup
from distutils.extension import Extension
setup(name='foobar',
      version='1.0',
      ext_modules=[
          Extension('foopkg.foo', ['foo.c']),
          Extension('barpkg.bar', ['bar.c']),
          ],
      )

For more details, see the setuptools documentation