How urgent are various setuptools deprecation warnings?

[mgorny]

Hello,

I'm one of the @gentoo developers responsible for maintaining Python packages in our distribution. Some time ago, we've modified our package manager to catch setuptools deprecation warnings in package build logs and warn us verbosely about them.

In my experience it seems that setuptools warnings are pretty common among various packages and often go unnoticed for a long time. Some of them seem minor, e.g. regarding renamed setup.cfg keys. Sometimes I felt like I was the only person submitting patches for that.

Unfortunately, as you probably know there's a very large number of Python packages that are no longer maintained yet remain relevant as dependencies of other packages. In case of these packages, the deprecation warnings are probably there to stay, unless someone actively forks the project (which doesn't happen often).

Therefore, my question: how important should we consider various deprecation warnings to be? In particular, should we be worried that e.g. one day we'd have to mass-fix packages using dashes in setup.cfg keys? Considering the above, in many cases this would mean we'd have to maintain patches for them for the foreseeable future.

I suppose the problem is even greater for users who do not use distribution packages but just fetch upstream distributions via pypi. For unmaintained packages, they can't really expect anyone to either release a fixed version, or add a pin on older setuptools version — so if setuptools turned deprecation warnings into errors, they would no longer be installable.