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A comment like `# yapf: disable # fmt: skip` contains both an fmt: off directive and fmt: skip. generate_ignored_nodes() already treats such a comment as fmt: skip, but the rest of the conversion still treated it as fmt: off. As a trailing comment it was rejected (a trailing fmt: off is invalid), so the line was formatted anyway; as an own-line comment inside brackets the comment was emitted twice and grew on every run, failing the stability check. Let fmt: skip win consistently.
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chrikrah
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Nov 8, 2026
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@fizzbeom nothing here blocks a merge from my side at 446b2ea. Reverting comments.py with your case file kept fails the new case:
# black from the exported 446b2ea tree, Python 3.12
$ python -m pytest tests -q -p no:cacheprovider --ignore=tests/test_blackd.py
620 passed, 3 skipped, 31 subtests passed
# src/black/comments.py reverted to b4f1fca, test data kept
$ python -m pytest tests/test_format.py -q -p no:cacheprovider -k fmt
FAILED tests/test_format.py::test_simple_format[fmtskip_with_fmt_off_in_same_comment]
1 failed, 66 passed, 248 deselected
# not run: tests/test_blackd.py (needs the d extra)
If a later push touches comments.py, I can rerun the revert check against it.
cobaltt7
reviewed
Nov 12, 2026
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Add unformatted lines after the trailing and own-line cases so the test shows the following code is still formatted.
…mt-off-in-same-comment # Conflicts: # CHANGES.md
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Description
A comment that contains both an fmt: off directive and
# fmt: skip, such as# yapf: disable # fmt: skip(common when migrating from yapf), is handledinconsistently.
generate_ignored_nodes()already treats it as# fmt: skip, butthe rest of the conversion still treats it as
# fmt: off:As a trailing comment, the line is formatted anyway, while
# noqa # fmt: skipis left alone:
becomes
x = [1, 2] # yapf: disable # fmt: skip.As an own-line comment inside brackets, Black crashes with "produced different
code on the second pass", because the comment is emitted twice and grows on
every run:
This change lets
# fmt: skipwin consistently, so such a comment behaves the sameas a plain
# fmt: skip. I found it by inserting fmt comments into the existingtest cases and running Black with its equivalence and stability checks.
Checklist - did you ...
--previewstyle, following the stability policy?CHANGES.mdif necessary?This PR was generated with AI (Claude Code).