Constraints files with spaces

[henryiii]

Summary

uv pip doesn't support constraint files with spaces:

$ echo "pytest~=7" > "constraints file.txt"
$ uv pip install pytest -c "constraints file.txt"
error: File not found: `constraints`

While pip does:

$ .venv/bin/pip install pytest -c "constraints file.txt"
ERROR: Invalid requirement: 'pytest~=7': Expected end or semicolon (after name and no valid version specifier)
    pytest~=7
          ^ (from line 1 of constraints file.txt)

(Ignore the fact I don't know how to write a constraint file, oops)

Note this is different than PIP_CONSTRAINT, which does not support spaces, and instead requires URIs since spaces are used to input multiple files.

I was trying to use uv in more places in cibuildwheel and ran into this, we test paths with spaces since they are common on Windows. pypa/cibuildwheel#2322

Platform

All

Version

uv 0.6.10 (Homebrew 2025-03-26) (and others)

Python version

No response

[charliermarsh]

Yeah we use the same syntax here and in the constraints environment variable, I think. What seems like it might be right?

[henryiii]

You can do -c multiple times. Sadly, you can't do that with an environment variable, so that's why the spaces are required there (I don't like using spaces there, but pip couldn't change it due to backcompat). But it shouldn't be in the command line, spaces are supported there!

[charliermarsh]

Clap doesn't have any way for us to differentiate in the parsing here. We'd need something like clap-rs/clap#3796.