The setuptools team no longer wants to support setup.py as the build tool, hence all direct invocations of setup.py are effectively deprecated in favor of invocations via purpose-built and/or standards-based CLI tools like pip, build and tox.

Builds might give warnings like this:

/usr/lib/python3.10/site-packages/setuptools/command/install.py:34: SetuptoolsDeprecationWarning: setup.py install is deprecated. Use build and pip and other standards-based tools.

For more details see:

https://blog.ganssle.io/articles/2021/10/setup-py-deprecated.html

https://discuss.python.org/t/custom-build-steps-moving-bokeh-off-setup-py/16128/3

We have a lot of custom functionality in setup.py and need to investigate how to handle this. It's important to note that setup.py itself is not deprecated, it can still be used to customize builds. But direct invocation of it is.

That maybe also means we should get rid of custom commands there that are not directly related to the build. E.g. syncing translations could be handled by separate scripts and don't need to be setup.py commands.