v0.12.0

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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)

v0.11.13

Compare Source

Preview features

• [airflow] Add unsafe fix for module moved cases (AIR301,AIR311,AIR312,AIR302) (#​18367,#​18366,#​18363,#​18093)
• [refurb] Add coverage of set and frozenset calls (FURB171) (#​18035)
• [refurb] Mark FURB180 fix unsafe when class has bases (#​18149)

Bug fixes

• [perflint] Fix missing parentheses for lambda and ternary conditions (PERF401, PERF403) (#​18412)
• [pyupgrade] Apply UP035 only on py313+ for get_type_hints() (#​18476)
• [pyupgrade] Make fix unsafe if it deletes comments (UP004,UP050) (#​18393, #​18390)

Rule changes

• [fastapi] Avoid false positive for class dependencies (FAST003) (#​18271)

Documentation

• Update editor setup docs for Neovim and Vim (#​18324)

Other changes

• Support Python 3.14 template strings (t-strings) in formatter and parser (#​17851)