feat: lock dependencies that are not relevant to the platform the compile is running on

[rbtcollins]

uv 0.1.44

With this requirements input file:

jupyterlab==4.2.0

running this command: uv pip compile --generate-hashes --no-header --no-strip-extras --python-version=3.11.9 -o foo.txt foo.in on a Linux host generates a foo.txt file that does not contain 'appnope'.

appnope is a platform_system specific dependency of the ipykernel:

https://github.com/ipython/ipykernel/blob/v6.29.4/pyproject.toml#L33
'appnope;platform_system=="Darwin"',

We want to lock our requirements, but having contributors run uv pip compile for every distinct platform seems like unnecessary toil. Even if a perfect job isn't possible, doing a usually-good-enough job would be fantastic.

Concrete proposal:

• when encountering a platform specific conditional dependency, include it, preserving the condition. And for its dependencies, whatever they are, inject the same condition unless an alternative path leads to their unconditional inclusion.

[charliermarsh]

You can do something like this to build a single requirements file for both platforms: #2679 (comment)

[charliermarsh]

Unclear if we'll offer something like this in the pip compile API directly. We're already building platform-agnostic resolution support atop lockfiles. Perhaps as part of that we'll offer outputting a requirements file.

[juledwar]

You can do something like this to build a single requirements file for both platforms: #2679 (comment)

What about allowing the use of multiple --platform flags? Obviously it would need to do environment markers.

[charliermarsh]

By the way: we now support --universal which does this!

(We may eventually support allowing multiple --python-platform flags as a less general solution.)

[juledwar]

I noticed --universal but I don't want everything as it slows down the whole run. I've gone from 1 hour on pip-compile to 5 minutes with UV because of this!