F821 not recognizing requires-python in pyproject.toml

[CNSeniorious000]

I tried to use anext and aiter in a project configured with requires-python = "~=3.10", but Ruff still complaining

F821 Undefined name `anext`. Consider specifying `requires-python = ">= 3.10"` or `tool.ruff.target-version = "py310"` in your `pyproject.toml` file.
  |
8 | async def main():
9 |     print(anext(g()))
  |           ^^^^^ F821
  |

Here is a reproduction repository:

https://github.com/CNSeniorious000/ruff-F821-repro

See these workflow logs:

https://github.com/CNSeniorious000/ruff-F821-repro/actions/runs/12198261365/job/34029609880#step:5:13

[charliermarsh]

If you add [tool.ruff] (even followed by nothing else) to your pyproject.toml, then we'll read the requires-python.

[CNSeniorious000]

Thank you! I'm surprised this workaround is needed.

[MichaReiser]

So am I! I'd expect Ruff to pick up the pyproject.toml as the root even if it has no tool.ruff section and there's no other configuration in any ancestor directory. However, that's probably a breaking change