astral-sh/ruff

`PTH*`: Incorrect suggestion to use `Pathlib` when using file descriptors

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#17,699 opened on Apr 29, 2025

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 (7 comments) (0 reactions) (0 assignees)Rust (2,088 forks)batch import
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Description

Multiple pathlib rules recommend the use of pathlib.Path over their os equivalent even when they're used with a bytes string or directory descriptor which aren't supported by pathlib.

One such example is

import os
os.listdir(1)

$ ruff --version
ruff 0.11.7
$ ruff check --isolated --select PTH208 t.py
t.py:2:1: PTH208 Use `pathlib.Path.iterdir()` instead.
  |
1 | import os
2 | os.listdir(1)
  | ^^^^^^^^^^ PTH208
  |

Found 1 error.

Past instances of the same or similar error:

Contributor guide

Research direction
Examine the Ruff source code for PTH rules (PTH208 etc.) to understand how they detect os functions and add a check to skip when the argument is an integer (file descriptor) or bytes string, as pathlib does not support these.
Tech stack
rustpython
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
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Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
RustPython
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60