Status of `numpy.distutils` and migration advice#

numpy.distutils has been deprecated in NumPy 1.23.0. It will be removed for Python 3.12; for Python <= 3.11 it will not be removed until 2 years after the Python 3.12 release (Oct 2025).

Warning

numpy.distutils is only tested with setuptools < 60.0, newer versions may break. See Interaction of numpy.distutils with setuptools for details.

Migration advice#

There are several build systems which are good options to migrate to. Assuming you have compiled code in your package (if not, you have several good options, e.g. the build backends offered by Poetry, Hatch or PDM) and you want to be using a well-designed, modern and reliable build system, we recommend:

Meson, and the meson-python build backend
CMake, and the scikit-build-core build backend

If you have modest needs (only simple Cython/C extensions; no need for Fortran, BLAS/LAPACK, nested setup.py files, or other features of numpy.distutils) and have been happy with numpy.distutils so far, you can also consider switching to setuptools. Note that most functionality of numpy.distutils is unlikely to be ported to setuptools.

Moving to Meson#

SciPy has moved to Meson and meson-python for its 1.9.0 release. During this process, remaining issues with Meson’s Python support and feature parity with numpy.distutils were resolved. Note: parity means a large superset (because Meson is a good general-purpose build system); only a few BLAS/LAPACK library selection niceties are missing. 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:

NumPy will migrate to Meson for the 1.26 release.

Moving to CMake / scikit-build#

The next generation of scikit-build is called scikit-build-core. Where the older scikit-build used setuptools underneath, the rewrite does not. Like Meson, CMake is a good general-purpose build system.

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
SIMD intrinsics support
Support for the NumPy-specific .src templating format for .c/.h files

The most widely used feature is nested setup.py files. This feature may perhaps still be ported to setuptools in the future (it needs a volunteer though, 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

Interaction of `numpy.distutils` with `setuptools`#

It is recommended to use setuptools < 60.0. Newer versions may work, but are not guaranteed to. The reason for this is that setuptools 60.0 enabled a vendored copy of distutils, including backwards incompatible changes that affect some functionality in numpy.distutils.

If you are using only simple Cython or C extensions with minimal use of numpy.distutils functionality beyond nested setup.py files (its most popular feature, see Configuration), then latest setuptools is likely to continue working. In case of problems, you can also try SETUPTOOLS_USE_DISTUTILS=stdlib to avoid the backwards incompatible changes in setuptools.

Whatever you do, it is recommended to put an upper bound on your setuptools build requirement in pyproject.toml to avoid future breakage - see For downstream package authors.

Status of numpy.distutils and migration advice#