ruff analyze graph | head -n 10 panics

[tpgillam]

It seems like ruff analyze graph is sometimes unhappy when its output isn't fully consumed.

Tested with ruffs 0.6.6 and 0.6.7:

> uv run ruff analyze graph -q | wc -l
2382

> uv run ruff analyze graph -q | head -n 10

<snip 10 correct lines of output>

error: Ruff crashed. If you could open an issue at:

    https://github.com/astral-sh/ruff/issues/new?title=%5BPanic%5D

...quoting the executed command, along with the relevant file contents and `pyproject.toml` settings, we'd be very appreciative!

thread 'main' panicked at library/std/src/io/stdio.rs:1118:9:
failed printing to stdout: Broken pipe (os error 32)
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

A full example to reproduce, starting in an otherwise empty directory, would be:

git clone https://github.com/Eomys/pyleecan.git --depth=1
uv init
uv add ruff==0.6.7
uv run ruff analyze graph | head -n 10

edit: above is running on MacOS 14.6.1 . Although head is the GNU version from homebrew's coreutils

[MichaReiser]

That's probably due to a println usage. We should use writeln instead and propagate the error when the pipe breaks

[pixelb]

Just a suggestion to not propagate pipe "errors", as this is not really an error in the normal sense
https://www.pixelbeat.org/programming/sigpipe_handling.html

[charliermarsh]

I got it.

[BurntSushi]

This is how ripgrep handles pipe errors: https://github.com/BurntSushi/ripgrep/blob/bf63fe8f258afc09bae6caa48f0ae35eaf115005/crates/core/main.rs#L55-L61

There are other approaches, but this is my favorite because:

• It doesn't require any platform specific APIs.
• It doesn't require inspecting or dealing with errors specially every time writeln! is called. You just propagate it like normal and only treat it differently at the top-level of the program in one place.
• It matches the expected behavior: a pipe error should make the program stop working and exit gracefully.

But yes, basically any println! automatically introduces a potential bug of this variety.