How to turn backend warnings into errors?

In https://github.com/scikit-hep/pyhf/pull/1881 I noticed and fixed a SetuptoolsDeprecationWarning that pyhf had in its setup. As pyhf runs build in its CI to ensure things are working I would like to have these warnings get turned into errors so that the dev team is alerted to them in advance (I just noticed this SetuptoolsDeprecationWarning by looking at the logs by chance).

My naive attempt at

$ python -Werror -m build .

doesn’t work, but I guess I’m unclear on how one should pass in warning filters to build and the commands that it will run as

$ python -m build --config-setting=-Werror .

also doesn’t work (though that makes sense as --config-setting is going to the backend (setuptools) and not to Python).

[layday]

It expects the fully-qualified module name, which in this case would be setuptools.config.setupcfg. You can filter using regexes with the programmatic API but not with -W or the env var.

[matthewfeickert]

You can filter using regexes with the programmatic API but not with -W or the env var.

Thanks @layday — this is the last bit that I was missing.