formatter: Two iterations required to converge on specific comment + slice case

[aneeshusa]

Tested on ruff v0.3.2 and main (dacec73). No ruff config.
Minimized from a file at $WORK; this cropped up during one of my final rebases to switch to ruff.
Not a blocker since the final formatting is stable.
black 24.2.0 accepts both the original and final style;
it rewrites the intermediate style to the final style.

Input:

repro(
    "some long string that takes up some space"
)[  # some long comment also taking up space
    0
]

1st run of ruff gives:

repro(
    "some long string that takes up some space"
)[0]  # some long comment also taking up space

2nd and beyond runs give:

repro("some long string that takes up some space")[
    0
]  # some long comment also taking up space

Script used

#!/usr/bin/env bash

# no errexit
set -o nounset
set -o pipefail

tmp_dir="$(mktemp -d)"
cleanup() {
    rm -rf "${tmp_dir}"
}
trap cleanup EXIT INT QUIT TERM

cat >"${tmp_dir}/repro.py" <<EOF
repro(
    "some long string that takes up some space"
)[  # some long comment also taking up space
    0
]
EOF

cd ~/code/ruff
git checkout "${1}"
ruff=(cargo run --quiet --package=ruff --)

echo -e '\nStarting hash of file'
(cd "${tmp_dir}" && sha256sum "./repro.py")
cat "${tmp_dir}/repro.py"

echo -e '\nFirst run'
"${ruff[@]}" format --isolated --target-version py310 --no-cache "${tmp_dir}/repro.py"
(cd "${tmp_dir}" && sha256sum "./repro.py")
cat "${tmp_dir}/repro.py"

echo -e '\nSecond run'
"${ruff[@]}" format --isolated --target-version py310 --no-cache "${tmp_dir}/repro.py"
(cd "${tmp_dir}" && sha256sum "./repro.py")
cat "${tmp_dir}/repro.py"

echo -e '\nThird run'
"${ruff[@]}" format --isolated --target-version py310 --no-cache "${tmp_dir}/repro.py"
(cd "${tmp_dir}" && sha256sum "./repro.py")

Didn't see any specific issues for this non-single-step-convergence, let me know if I missed one.

[charliermarsh]

Thanks!

[MichaReiser]

Thanks for the excellent write up. It made it super easy to reproduce and fix (including test cases)