Missing dependencies on Matplotlib

[David-OConnor]

This likely affects other projects as well.

Warehouse data
requires_dist: null

from Matplotlib 3.1.1's dist-info/METADATA file:

Requires-Dist: cycler (>=0.10)
Requires-Dist: kiwisolver (>=1.0.1)
Requires-Dist: pyparsing (!=2.0.4,!=2.1.2,!=2.1.6,>=2.0.1)
Requires-Dist: python-dateutil (>=2.1)
Requires-Dist: numpy (>=1.11)

[David-OConnor]

Found this related issue. From what I gather:

• The requires_dist field takes info from whatever dist was uploaded first. Ie if it was a source-dist, it shows null.
• There's no distinction between no dependencies, and can't-find-dependencies.
• Package info on the warehouse won't be changed once set, even if incorrect.

Is this right? I may build an api to cache this; would be more appropriate in the json warehouse api, but I'll press if this is a won't-fix.

Can we consider all dependency info on the warehouse unreliable, or just ones that show null?

[David-OConnor]

WIP

[di]

Can we consider all dependency info on the warehouse unreliable

Yes, see https://dustingram.com/articles/2018/03/05/why-pypi-doesnt-know-dependencies/, which was linked from #6226.

[David-OConnor]

Thanks. IMO this is not resolved and should be attacked by the warehouse. This is technically easy to fix - not find a perfect solution, but provide more accurate data than we currently have. Downloading the package, and checking the METADATA provides the correct info in most of the cases I've seen.

Python's an elegant language with a fucked packaging system - this is the perfect place to fix it. We will not resolve deps for all packages, but can do it for most.