Ruff format on multiple directories returns inconsistent results #21081
Description
Summary
The pwndbg project - https://github.com/pwndbg/pwndbg/ - is using ruff format to format the codebase. We have found that using ruff format will inconsistently report formatting errors when running it with multiple directories.
Reproduce
Pwndbg uses Ruff 0.4.10, however I have reproduced this with the latest version of Ruff as well. See the note at the end.
Clone the pwndbg repo on a version where this applies:
git clone --depth 1 https://github.com/pwndbg/pwndbg.git --branch 2025.10.20
cd pwndbgWithin the nested pwndbg/ directory, there are 5 files with some formatting errors.
If you run this, you will see the errors (this uses our specific version of ruff through a virtual environment with uv):
uv run --group lint ruff format --check --diff pwndbgHowever, if you add additional directories to be formatted, these errors will not always be reported.
uv run --group lint ruff format --check --diff pwndbg pwndbginit tests *.py scriptsYou can run it in a loop of 100, and see it prints out the diff only on rare cases:
for i in `seq 1 100`; do uv run --group lint ruff format --check --diff pwndbg pwndbginit tests *.py scripts; done
As you remove directories from the list to be formatted, the likelihood of ruff format finding the formatting errors in the pwndbg/ directory increases.
Note that if you don't use the uv virtual environment, and instead use the latest version of Ruff, 0.14.2, the same results apply. It will still find an inconsistent number of files with errors between different runs (the numbers vary from 0.4.10, as the new errors are resulting from newer versions of Ruff changing how things are formatted)
Version
0.14.2 and 0.4.10