Can't install PyYAML with pip if setuptools isn't installed

Trying to install PyYAML using pip when setuptools isn’t installed results in this:

# python3 -mpip install --user pyyaml
Collecting pyyaml
  Using cached PyYAML-5.3.1.tar.gz (269 kB)
    ERROR: Command errored out with exit status 1:
     command: /usr/bin/python3 -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-4gsyi4k8/pyyaml/setup.py'"'"'; __file__='"'"'/tmp/pip-install-4gsyi4k8/pyyaml/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base /tmp/pip-pip-egg-info-p9iajmh9
         cwd: /tmp/pip-install-4gsyi4k8/pyyaml/
    Complete output (3 lines):
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
    ModuleNotFoundError: No module named 'setuptools'
    ----------------------------------------
ERROR: Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.

Ideally, PyYAML should include a pyproject.toml file declaring build-time dependencies, so that pip can fetch them automatically.

[IRDonch]

I suppose a pyproject.toml file could be added, but why not just install setuptools?

You could say that about any dependency. 🤷 Ideally, every project should fetch all of its own dependencies automatically.

[nitzmahone]

The 5.4 release will include some packaging updates that start to clean up the distutils/setuptools mess, but due to the age of the Pythons/pips we still support, we can’t wholesale switch to a PEP517 (pyproject.toml) build yet. Maybe in 6.0, depending on what Pythons we drop support for, but that’s still TBD.