Error adding dependency that uses setup.py & distutils when on Python 3.10

[ntessman-capsule]

I'm not sure if this is an issue with uv specifically or if it's some deadly combination of python versions, but I haven't found anything useful in my searches.

I have a repository pinned at 3.10.14, and I have a dependency that is using setuptools/distutils. When trying to install the dependency, Python is failing to find the distutils package. This is confusing to me for two reasons:

1. Since I'm on 3.10.14, distutils should exist in the stdlib but be deprecated.
2. Even if distutils doesn't exist, setuptools is being imported before distutils and should have patched it.

The other issues I've found are along these lines: https://github.com/astral-sh/uv/issues/7183, but I'm not using Python >=3.12 so this feels like a different issue.

I'm in the process of porting the project repository from pipenv to uv. Pipenv installs the dependency without an issue, which leads me to believe it's something to do with uv. This error happens whether installing the dependency locally or from an index.

I'm using uv 0.4.24 via Homebrew on Apple Silicon.

Steps to reproduce:

1. Clone the repro repository
2. Run cd project
3. Run uv add ../dependency --verbose

Command output:

~/work/uv-repro/project master ❯ uv add ../dependency --verbose
DEBUG uv 0.4.24 (Homebrew 2024-10-17)
DEBUG Found project root: `/Users/ntessman/work/uv-repro/project`
DEBUG No workspace root found, using project root
DEBUG Reading requests from `/Users/ntessman/work/uv-repro/project/.python-version`
DEBUG The virtual environment's Python version satisfies `Python 3.10.14`
DEBUG Using request timeout of 30s
DEBUG No static `pyproject.toml` available for: file:///Users/ntessman/work/uv-repro/dependency (MissingPyprojectToml)
DEBUG Acquired lock for `/Users/ntessman/.cache/uv/sdists-v4/path/eaddab2df3eda492`
DEBUG Preparing metadata for: file:///Users/ntessman/work/uv-repro/dependency
DEBUG Ignoring empty directory
DEBUG Resolving build requirements
DEBUG Solving with installed Python version: 3.10.14
DEBUG Solving with target Python version: >=3.10.14
DEBUG Adding direct dependency: setuptools>=40.8.0
DEBUG No cache entry for: https://pypi.org/simple/setuptools/
WARN Skipping file for setuptools: setuptools-0.6b1-py2.3.egg
WARN Skipping file for setuptools: setuptools-0.6b1-py2.4.egg
WARN Skipping file for setuptools: setuptools-0.6b2-py2.3.egg
WARN Skipping file for setuptools: setuptools-0.6b2-py2.4.egg
WARN Skipping file for setuptools: setuptools-0.6b3-py2.3.egg
WARN Skipping file for setuptools: setuptools-0.6b3-py2.4.egg
WARN Skipping file for setuptools: setuptools-0.6b4-py2.3.egg
WARN Skipping file for setuptools: setuptools-0.6b4-py2.4.egg
WARN Skipping file for setuptools: setuptools-0.6c1-py2.3.egg
WARN Skipping file for setuptools: setuptools-0.6c1-py2.4.egg
WARN Skipping file for setuptools: setuptools-0.6c10-1.src.rpm
WARN Skipping file for setuptools: setuptools-0.6c10-py2.3.egg
WARN Skipping file for setuptools: setuptools-0.6c10-py2.4.egg
WARN Skipping file for setuptools: setuptools-0.6c10-py2.5.egg
WARN Skipping file for setuptools: setuptools-0.6c10-py2.6.egg
WARN Skipping file for setuptools: setuptools-0.6c10.win32-py2.3.exe
WARN Skipping file for setuptools: setuptools-0.6c10.win32-py2.4.exe
WARN Skipping file for setuptools: setuptools-0.6c10.win32-py2.5.exe
WARN Skipping file for setuptools: setuptools-0.6c10.win32-py2.6.exe
WARN Skipping file for setuptools: setuptools-0.6c11-1.src.rpm
WARN Skipping file for setuptools: setuptools-0.6c11-py2.3.egg
WARN Skipping file for setuptools: setuptools-0.6c11-py2.4.egg
WARN Skipping file for setuptools: setuptools-0.6c11-py2.5.egg
WARN Skipping file for setuptools: setuptools-0.6c11-py2.6.egg
WARN Skipping file for setuptools: setuptools-0.6c11-py2.7.egg
WARN Skipping file for setuptools: setuptools-0.6c11.win32-py2.3.exe
WARN Skipping file for setuptools: setuptools-0.6c11.win32-py2.4.exe
WARN Skipping file for setuptools: setuptools-0.6c11.win32-py2.5.exe
WARN Skipping file for setuptools: setuptools-0.6c11.win32-py2.6.exe
WARN Skipping file for setuptools: setuptools-0.6c11.win32-py2.7.exe
WARN Skipping file for setuptools: setuptools-0.6c2-py2.3.egg
WARN Skipping file for setuptools: setuptools-0.6c2-py2.4.egg
WARN Skipping file for setuptools: setuptools-0.6c3-py2.3.egg
WARN Skipping file for setuptools: setuptools-0.6c3-py2.4.egg
WARN Skipping file for setuptools: setuptools-0.6c3-py2.5.egg
WARN Skipping file for setuptools: setuptools-0.6c4-1.src.rpm
WARN Skipping file for setuptools: setuptools-0.6c4-py2.3.egg
WARN Skipping file for setuptools: setuptools-0.6c4-py2.4.egg
WARN Skipping file for setuptools: setuptools-0.6c4-py2.5.egg
WARN Skipping file for setuptools: setuptools-0.6c4.win32-py2.3.exe
WARN Skipping file for setuptools: setuptools-0.6c4.win32-py2.4.exe
WARN Skipping file for setuptools: setuptools-0.6c4.win32-py2.5.exe
WARN Skipping file for setuptools: setuptools-0.6c5-1.src.rpm
WARN Skipping file for setuptools: setuptools-0.6c5-py2.3.egg
WARN Skipping file for setuptools: setuptools-0.6c5-py2.4.egg
WARN Skipping file for setuptools: setuptools-0.6c5-py2.5.egg
WARN Skipping file for setuptools: setuptools-0.6c5.win32-py2.3.exe
WARN Skipping file for setuptools: setuptools-0.6c5.win32-py2.4.exe
WARN Skipping file for setuptools: setuptools-0.6c5.win32-py2.5.exe
WARN Skipping file for setuptools: setuptools-0.6c6-1.src.rpm
WARN Skipping file for setuptools: setuptools-0.6c6-py2.3.egg
WARN Skipping file for setuptools: setuptools-0.6c6-py2.4.egg
WARN Skipping file for setuptools: setuptools-0.6c6-py2.5.egg
WARN Skipping file for setuptools: setuptools-0.6c6.win32-py2.3.exe
WARN Skipping file for setuptools: setuptools-0.6c6.win32-py2.4.exe
WARN Skipping file for setuptools: setuptools-0.6c6.win32-py2.5.exe
WARN Skipping file for setuptools: setuptools-0.6c7-1.src.rpm
WARN Skipping file for setuptools: setuptools-0.6c7-py2.3.egg
WARN Skipping file for setuptools: setuptools-0.6c7-py2.4.egg
WARN Skipping file for setuptools: setuptools-0.6c7-py2.5.egg
WARN Skipping file for setuptools: setuptools-0.6c7.win32-py2.3.exe
WARN Skipping file for setuptools: setuptools-0.6c7.win32-py2.4.exe
WARN Skipping file for setuptools: setuptools-0.6c7.win32-py2.5.exe
WARN Skipping file for setuptools: setuptools-0.6c8-1.src.rpm
WARN Skipping file for setuptools: setuptools-0.6c8-py2.3.egg
WARN Skipping file for setuptools: setuptools-0.6c8-py2.4.egg
WARN Skipping file for setuptools: setuptools-0.6c8-py2.5.egg
WARN Skipping file for setuptools: setuptools-0.6c8.win32-py2.3.exe
WARN Skipping file for setuptools: setuptools-0.6c8.win32-py2.4.exe
WARN Skipping file for setuptools: setuptools-0.6c8.win32-py2.5.exe
WARN Skipping file for setuptools: setuptools-0.6c9-1.src.rpm
WARN Skipping file for setuptools: setuptools-0.6c9-py2.3.egg
WARN Skipping file for setuptools: setuptools-0.6c9-py2.4.egg
WARN Skipping file for setuptools: setuptools-0.6c9-py2.5.egg
WARN Skipping file for setuptools: setuptools-0.6c9-py2.6.egg
WARN Skipping file for setuptools: setuptools-0.6c9.win32-py2.3.exe
WARN Skipping file for setuptools: setuptools-0.6c9.win32-py2.4.exe
WARN Skipping file for setuptools: setuptools-0.6c9.win32-py2.5.exe
WARN Skipping file for setuptools: setuptools-18.3.1-py3.4.egg
DEBUG Searching for a compatible version of setuptools (>=40.8.0)
DEBUG Selecting: setuptools==75.2.0 [compatible] (setuptools-75.2.0-py3-none-any.whl)
DEBUG No cache entry for: https://files.pythonhosted.org/packages/31/2d/90165d51ecd38f9a02c6832198c13a4e48652485e2ccf863ebb942c531b6/setuptools-75.2.0-py3-none-any.whl.metadata
DEBUG Tried 1 versions: setuptools 1
DEBUG Split specific environment resolution took 0.593s
DEBUG Installing in setuptools==75.2.0 in /Users/ntessman/.cache/uv/builds-v0/.tmpLQrXQ0
DEBUG Requirement already cached: setuptools==75.2.0
DEBUG Installing build requirement: setuptools==75.2.0
DEBUG Creating PEP 517 build environment
DEBUG Calling `setuptools.build_meta:__legacy__.get_requires_for_build_wheel()`
DEBUG Traceback (most recent call last):
DEBUG   File "<string>", line 14, in <module>
DEBUG   File "/Users/ntessman/.cache/uv/builds-v0/.tmpLQrXQ0/lib/python3.10/site-packages/setuptools/build_meta.py", line 332, in get_requires_for_build_wheel
DEBUG     return self._get_build_requires(config_settings, requirements=[])
DEBUG   File "/Users/ntessman/.cache/uv/builds-v0/.tmpLQrXQ0/lib/python3.10/site-packages/setuptools/build_meta.py", line 302, in _get_build_requires
DEBUG     self.run_setup()
DEBUG   File "/Users/ntessman/.cache/uv/builds-v0/.tmpLQrXQ0/lib/python3.10/site-packages/setuptools/build_meta.py", line 516, in run_setup
DEBUG     super().run_setup(setup_script=setup_script)
DEBUG   File "/Users/ntessman/.cache/uv/builds-v0/.tmpLQrXQ0/lib/python3.10/site-packages/setuptools/build_meta.py", line 318, in run_setup
DEBUG     exec(code, locals())
DEBUG   File "<string>", line 2, in <module>
DEBUG ModuleNotFoundError: No module named 'distutils.command.upload'
DEBUG Released lock at `/Users/ntessman/.cache/uv/sdists-v4/path/eaddab2df3eda492/.lock`
error: Build backend failed to determine requirements with `build_wheel()` (exit status: 1)

[stderr]
Traceback (most recent call last):
  File "<string>", line 14, in <module>
  File "/Users/ntessman/.cache/uv/builds-v0/.tmpLQrXQ0/lib/python3.10/site-packages/setuptools/build_meta.py", line 332, in get_requires_for_build_wheel
    return self._get_build_requires(config_settings, requirements=[])
  File "/Users/ntessman/.cache/uv/builds-v0/.tmpLQrXQ0/lib/python3.10/site-packages/setuptools/build_meta.py", line 302, in _get_build_requires
    self.run_setup()
  File "/Users/ntessman/.cache/uv/builds-v0/.tmpLQrXQ0/lib/python3.10/site-packages/setuptools/build_meta.py", line 516, in run_setup
    super().run_setup(setup_script=setup_script)
  File "/Users/ntessman/.cache/uv/builds-v0/.tmpLQrXQ0/lib/python3.10/site-packages/setuptools/build_meta.py", line 318, in run_setup
    exec(code, locals())
  File "<string>", line 2, in <module>
ModuleNotFoundError: No module named 'distutils.command.upload'