v0.12.1

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Preview features

• [flake8-errmsg] Extend EM101 to support byte strings (#​18867)
• [flake8-use-pathlib] Add autofix for PTH202 (#​18763)
• [pygrep-hooks] Add AsyncMock methods to invalid-mock-access (PGH005) (#​18547)
• [pylint] Ignore __init__.py files in (PLC0414) (#​18400)
• [ruff] Trigger RUF037 for empty string and byte strings (#​18862)
• [formatter] Fix missing blank lines before decorated classes in .pyi files (#​18888)

Bug fixes

• Avoid generating diagnostics with per-file ignores (#​18801)
• Handle parenthesized arguments in remove_argument (#​18805)
• [flake8-logging] Avoid false positive for exc_info=True outside logger.exception (LOG014) (#​18737)
• [flake8-pytest-style] Enforce pytest import for decorators (#​18779)
• [flake8-pytest-style] Mark autofix for PT001 and PT023 as unsafe if there's comments in the decorator (#​18792)
• [flake8-pytest-style] PT001/PT023 fix makes syntax error on parenthesized decorator (#​18782)
• [flake8-raise] Make fix unsafe if it deletes comments (RSE102) (#​18788)
• [flake8-simplify] Fix SIM911 autofix creating a syntax error (#​18793)
• [flake8-simplify] Fix false negatives for shadowed bindings (SIM910, SIM911) (#​18794)
• [flake8-simplify] Preserve original behavior for except () and bare except (SIM105) (#​18213)
• [flake8-pyi] Fix PYI041's fix causing TypeError with None | None | ... (#​18637)
• [perflint] Fix PERF101 autofix creating a syntax error and mark autofix as unsafe if there are comments in the list call expr (#​18803)
• [perflint] Fix false negative in PERF401 (#​18866)
• [pylint] Avoid flattening nested min/max when outer call has single argument (PLW3301) (#​16885)
• [pylint] Fix PLC2801 autofix creating a syntax error (#​18857)
• [pylint] Mark PLE0241 autofix as unsafe if there's comments in the base classes (#​18832)
• [pylint] Suppress PLE2510/PLE2512/PLE2513/PLE2514/PLE2515 autofix if the text contains an odd number of backslashes (#​18856)
• [refurb] Detect more exotic float literals in FURB164 (#​18925)
• [refurb] Fix FURB163 autofix creating a syntax error for yield expressions (#​18756)
• [refurb] Mark FURB129 autofix as unsafe if there's comments in the readlines call (#​18858)
• [ruff] Fix false positives and negatives in RUF010 (#​18690)
• Fix casing of analyze.direction variant names (#​18892)

Rule changes

• Fix f-string interpolation escaping in generated fixes (#​18882)
• [flake8-return] Mark RET501 fix unsafe if comments are inside (#​18780)
• [flake8-async] Fix detection for large integer sleep durations in ASYNC116 rule (#​18767)
• [flake8-async] Mark autofix for ASYNC115 as unsafe if the call expression contains comments (#​18753)
• [flake8-bugbear] Mark autofix for B004 as unsafe if the hasattr call expr contains comments (#​18755)
• [flake8-comprehension] Mark autofix for C420 as unsafe if there's comments inside the dict comprehension (#​18768)
• [flake8-comprehensions] Handle template strings for comprehension fixes (#​18710)
• [flake8-future-annotations] Add autofix (FA100) (#​18903)
• [pyflakes] Mark F504/F522/F523 autofix as unsafe if there's a call with side effect (#​18839)
• [pylint] Allow fix with comments and document performance implications (PLW3301) (#​18936)
• [pylint] Detect more exotic NaN literals in PLW0177 (#​18630)
• [pylint] Fix PLC1802 autofix creating a syntax error and mark autofix as unsafe if there's comments in the len call (#​18836)
• [pyupgrade] Extend version detection to include sys.version_info.major (UP036) (#​18633)
• [ruff] Add lint rule RUF064 for calling chmod with non-octal integers (#​18541)
• [ruff] Added cls.__dict__.get('__annotations__') check (RUF063) (#​18233)
• [ruff] Frozen dataclass default should be valid (RUF009) (#​18735)

Server

• Consider virtual path for various server actions (#​18910)

Documentation

• Add fix safety sections (#​18940,#​18841,#​18802,#​18837,#​18800,#​18415,#​18853,#​18842)
• Use updated pre-commit id (#​18718)
• [perflint] Small docs improvement to PERF401 (#​18786)
• [pyupgrade]: Use super(), not __super__ in error messages (UP008) (#​18743)
• [flake8-pie] Small docs fix to PIE794 (#​18829)
• [flake8-pyi] Correct collections-named-tuple example to use PascalCase assignment (#​16884)
• [flake8-pie] Add note on type checking benefits to unnecessary-dict-kwargs (PIE804) (#​18666)
• [pycodestyle] Clarify PEP 8 relationship to whitespace-around-operator rules (#​18870)

Other changes

• Disallow newlines in format specifiers of single quoted f- or t-strings (#​18708)
• [flake8-logging] Add fix safety section to LOG002 (#​18840)
• [pyupgrade] Add fix safety section to UP010 (#​18838)

v0.12.0

Compare Source

Check out the blog post for a migration
guide and overview of the changes!

Breaking changes

• Detection of more syntax errors

  Ruff now detects version-related syntax errors, such as the use of the match
  statement on Python versions before 3.10, and syntax errors emitted by
  CPython's compiler, such as irrefutable match patterns before the final
  case arm.

• New default Python version handling for syntax errors

  Ruff will default to the latest supported Python version (3.13) when
  checking for the version-related syntax errors mentioned above to prevent
  false positives in projects without a Python version configured. The default
  in all other cases, like applying lint rules, is unchanged and remains at the
  minimum supported Python version (3.9).

• Updated f-string formatting

  Ruff now formats multi-line f-strings with format specifiers to avoid adding a
  line break after the format specifier. This addresses a change to the Python
  grammar in version 3.13.4 that made such a line break a syntax error.

• rust-toolchain.toml is no longer included in source distributions

  The rust-toolchain.toml is used to specify a higher Rust version than Ruff's
  minimum supported Rust version (MSRV) for development and building release
  artifacts. However, when present in source distributions, it would also cause
  downstream package maintainers to pull in the same Rust toolchain, even if
  their available toolchain was MSRV-compatible.

Removed Rules

The following rules have been removed:

• suspicious-xmle-tree-usage
  (S320)

Deprecated Rules

The following rules have been deprecated:

• pandas-df-variable-name

Stabilization

The following rules have been stabilized and are no longer in preview:

• for-loop-writes (FURB122)
• check-and-remove-from-set (FURB132)
• verbose-decimal-constructor (FURB157)
• fromisoformat-replace-z (FURB162)
• int-on-sliced-str (FURB166)
• exc-info-outside-except-handler (LOG014)
• import-outside-top-level (PLC0415)
• unnecessary-dict-index-lookup (PLR1733)
• nan-comparison (PLW0177)
• eq-without-hash (PLW1641)
• pytest-parameter-with-default-argument (PT028)
• pytest-warns-too-broad (PT030)
• pytest-warns-with-multiple-statements (PT031)
• invalid-formatter-suppression-comment (RUF028)
• dataclass-enum (RUF049)
• class-with-mixed-type-vars (RUF053)
• unnecessary-round (RUF057)
• starmap-zip (RUF058)
• non-pep604-annotation-optional (UP045)
• non-pep695-generic-class (UP046)
• non-pep695-generic-function (UP047)
• private-type-parameter (UP049)

The following behaviors have been stabilized:

• [collection-literal-concatenation] (RUF005) now recognizes slices, in
  addition to list literals and variables.
• The fix for [readlines-in-for] (FURB129) is now marked as always safe.
• [if-else-block-instead-of-if-exp] (SIM108) will now further simplify
  expressions to use or instead of an if expression, where possible.
• [unused-noqa] (RUF100) now checks for file-level noqa comments as well
  as inline comments.
• [subprocess-without-shell-equals-true] (S603) now accepts literal strings,
  as well as lists and tuples of literal strings, as trusted input.
• [boolean-type-hint-positional-argument] (FBT001) now applies to types that
  include bool, like bool | int or typing.Optional[bool], in addition to
  plain bool annotations.
• [non-pep604-annotation-union] (UP007) has now been split into two rules.
  UP007 now applies only to typing.Union, while
  [non-pep604-annotation-optional] (UP045) checks for use of
  typing.Optional. UP045 has also been stabilized in this release, but you
  may need to update existing include, ignore, or noqa settings to
  accommodate this change.

Preview features

• [ruff] Check for non-context-manager use of pytest.raises, pytest.warns, and pytest.deprecated_call (RUF061) (#​17368)
• [syntax-errors] Raise unsupported syntax error for template strings prior to Python 3.14 (#​18664)

Bug fixes

• Add syntax error when conversion flag does not immediately follow exclamation mark (#​18706)
• Add trailing space around readlines (#​18542)
• Fix \r and \r\n handling in t- and f-string debug texts (#​18673)
• Hug closing } when f-string expression has a format specifier (#​18704)
• [flake8-pyi] Avoid syntax error in the case of starred and keyword arguments (PYI059) (#​18611)
• [flake8-return] Fix RET504 autofix generating a syntax error (#​18428)
• [pep8-naming] Suppress fix for N804 and N805 if the recommended name is already used (#​18472)
• [pycodestyle] Avoid causing a syntax error in expressions spanning multiple lines (E731) (#​18479)
• [pyupgrade] Suppress UP008 if super is shadowed (#​18688)
• [refurb] Parenthesize lambda and ternary expressions (FURB122, FURB142) (#​18592)
• [ruff] Handle extra arguments to deque (RUF037) (#​18614)
• [ruff] Preserve parentheses around deque in fix for unnecessary-empty-iterable-within-deque-call (RUF037) (#​18598)
• [ruff] Validate arguments before offering a fix (RUF056) (#​18631)
• [ruff] Skip fix for RUF059 if dummy name is already bound (#​18509)
• [pylint] Fix PLW0128 to check assignment targets in square brackets and after asterisks (#​18665)

Rule changes

• Fix false positive on mutations in return statements (B909) (#​18408)
• Treat ty: comments as pragma comments (#​18532)
• [flake8-pyi] Apply custom-typevar-for-self to string annotations (PYI019) (#​18311)
• [pyupgrade] Don't offer a fix for Optional[None] (UP007, UP045) (#​18545)
• [pyupgrade] Fix super(__class__, self) detection (UP008) (#​18478)
• [refurb] Make the fix for FURB163 unsafe for log2, log10, *args, and deleted comments (#​18645)

Server

• Support cancellation requests (#​18627)

Documentation

• Drop confusing second * from glob pattern example for per-file-target-version (#​18709)
• Update Neovim configuration examples (#​18491)
• [pylint] De-emphasize __hash__ = Parent.__hash__ (PLW1641) (#​18613)
• [refurb] Add a note about float literal handling (FURB157) (#​18615)