flit cannot be built

[seppeljordan]

The flit package cannot be built. This is due to a bug/missing feature in pip. This is addressed in pypa/pip#7394

We need to update pip as soon as a release including this change is published.

[seppeljordan]

@cyraxjoe This is currently in progress. Check out #383 if you want to see how things are going

For everyone who cares:

I identified the issue and it is two fold:

1. Pip cannot build flit>=2.0 as of version 19.3.1. A fix was already merged to master though.
2. nixpkgs cannot handle building flit_core without being explicitly told about it being a pyproject package. Check out section 15.17.2.2.1.1. of the nixpkgs manual (You have to scroll down a bit to find the relevant section, search for "format ?" in that document to find it). This is being addressed in Fix issues with building flit #383

[cyraxjoe]

Thank you for the update @seppeljordan (and your work on keeping alive pypi2nix!)

I temporarily end-up working around the issue by not regenerating my requirements.nix and using the current one for my project with flit-1.3. But this will become an issue when I decide to update my dependencies.

[seppeljordan]

You can use a constraints file in your requirements file to work around the issue:

in requirements.txt:

[YOUR REQUIREMENTS]

-c constraints.txt

in constraints.txt:

flit < 2.0

Let me know if this helps

[seppeljordan]

Should be resolved now since #383 was merged successfully.