numpy needs numpy/numpy#17776

the use of flit_core is making gimp fail because python2Packages.flit_core is disabled, which failing the eval as gimp is a darwin constituent https://gist.github.com/GrahamcOfBorg/f0aa782e418d7d426a7bf7a5a7372186

maybe we should revert the packaging bump until they figure out their existence.

the use of flit_core is making gimp fail because python2Packages.flit_core is disabled, which failing the eval as gimp is a darwin constituent https://gist.github.com/GrahamcOfBorg/f0aa782e418d7d426a7bf7a5a7372186

In principle the Python 3 flit can make a wheel for Python 2 (they're universal wheels). I've been avoiding this but can use this fact.

Easiest here is to just keep another package for Python 2.

In principle the Python 3 flit can make a wheel for Python 2 (they're universal wheels). I've been avoiding this but can use this fact.

I had a quick look at this approach. Fun stuff! So, in principle we could run the flit command, Python 3 version, to build the wheel. However, e.g. packaging uses PEP 517, so pip will attempt to use that method to find the backend. Then, it fails, because it cannot find the Python 3 version. Sigh.

Really the best approach here, if we were caring sufficiently for Python 2, would be to separate the wheel building part into a separate derivation. The installation function could then simply pick the universal wheel built with Python 3. Now I would still like to do that some day, and not for Python 2, but for other reasons, but not anytime soon.

So for now I suggest we keep the older packaging for Python 2 around.

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/upcoming-python-breakage/7554/19

Thank you @jonringer. There are about 900 failures left, which is about the same as it was before. I've updated to the latest pip.

After this was merged on staging:

$ nixos-rebuild build -I nixpkgs=.
building Nix...
building the system configuration...
error: pytest-xdist-2.1.0 not supported for interpreter python2.7
(use '--show-trace' to show detailed location information)

Seems to be caused by TeX Live depending on Python 2.

I have TeX Live working; will request pull later.