Resolve find-links paths relative to the configuration file

[NightRa]

One-liner

Relative find-links configuration to local path from a pyproject.toml or uv.toml is now relative to the config file

Summary

Background

One can configure find-links in a pyproject.toml or uv.toml file, which are located from the cli arg, system directory, user directory, or by traversing parent directories until one is encountered.

This PR addresses the following scenario:

• A project directory which includes a pyproject.toml or uv.toml file
• The config file includes a find-links option. (eg under [tool.uv] for pyproject.toml)
• The find-links option is configured to point to a local subdirectory in the project: packages/
• There is a subdirectory called subdir, which is the current working directory
• I run uv run my_script.py. This will locate the pyproject.toml in the parent directory

Current Behavior

• uv tries to use the path subdir/packages/ to find packages, and fails.

New Behavior

• uv tries to use the path packages/ to find the packages, and succeeds
• Specifically, any relative local find-links path will resolve to be relative to the configuration file.

Why is this behavior change OK?

• I believe no one depends on the behavior that a relative find-links when running in a subdir will refer to different directories each time
• Thus this change only allows a more common use case which didn't work previously.

Test Plan

• I re-created the setup mentioned above:

UvTest/
├── packages/
│   ├── colorama-0.4.6-py2.py3-none-any.whl
│   └── tqdm-4.67.1-py3-none-any.whl
├── subdir/
│   └── my_script.py
└── pyproject.toml

# pyproject.toml
[project]
name = "uvtest"
version = "0.1.0"
description = "Add your description here"
readme = "README.md"
requires-python = ">=3.12"
dependencies = [
    "tqdm>=4.67.1",
]

[tool.uv]
offline = true
no-index = true
find-links = ["packages/"]

• With working directory under subdir, previously, running uv sync --offline would fail resolving the tdqm package, and after the change it succeeds.
• Additionally, one can use uv sync --show-settings to show the actually-resolved settings - now having the desired path in flat_index.url.path

Alternative designs considered

• I considered modifying the impl Deserialize for IndexUrl to parse ahead of time directly with a base directory by having a custom Deserializer with a base dir field, but it seems to contradict the design of the serde Deserialize trait - which should work with all Deserializers

Future work

• Support for adjusting all other local-relative paths in Options would be desired, but is out of scope for the current PR.

[charliermarsh]

Thanks. It would be useful to include a test here (that fails on main but passes on this branch) to guard against regressions (and make sure we understand the problematic scenario).

[NightRa]

@charliermarsh

• A test corresponding to the scenario I described would need to have a whl file for some package.
• Which minimal test package would you consider appropriate for this?
• This would also imply it needs to be checked in the uv repository
• Where would be an appropriate location in the repository to hold this whl file for the test?

[charliermarsh]

We already have a few checked-in that you can use in ./scripts/links. Grep around for tests that use scripts/links for examples?

[NightRa]

@charliermarsh
Done.
Also checked the test fails on master and succeeds here.
Previously it would fail with:

error: Failed to read `--find-links` directory: C:\Users\...\AppData\Roaming\uv\tests\.tmpS7JaZu\temp\subdir\packages
  Caused by: The system cannot find the path specified. (os error 3)

[NightRa]

@charliermarsh Anything else required to merge here?

[charliermarsh]

No, I just need time to review the changes.

[NightRa]

Great, thanks for your time!

[NightRa]

Indeed wasn't sure about the &mut. Thanks for the fixes
Love the quick support. Would recommend. 10/10

[charliermarsh]

Yeah the &mut worked, I just generally prefer to use these kinds of immutability patterns. Thanks for the PR!