Python 3.15 Support

This is a tracking issue for Python 3.15 support.

PEP 810: Lazy imports

• UP026 needs lazy import support in libCST for fixes to work

  • https://github.com/astral-sh/ruff/pull/28616

• https://github.com/astral-sh/ruff/issues/25181

  • https://github.com/astral-sh/ruff/pull/28541

• https://github.com/astral-sh/ruff/issues/25170

  • https://github.com/astral-sh/ruff/pull/28459

• https://github.com/astral-sh/ruff/issues/26450

  • https://github.com/astral-sh/ruff/pull/26584

• https://github.com/astral-sh/ruff/issues/25418

  • https://github.com/astral-sh/ruff/pull/28262

PEP 798: Unpacking in comprehensions

• https://github.com/astral-sh/ruff/pull/25104
• C411, C418, and C419 diagnose the new unpacking comprehensions but cannot autofix them because the LibCST-based fixers do not support the syntax yet
  • https://github.com/astral-sh/ruff/pull/28616

Unicode 17

• https://github.com/astral-sh/ruff/pull/21229
• https://github.com/astral-sh/ruff/pull/26077
  • https://github.com/progval/unicode_names2/pull/61
  • https://github.com/progval/unicode_names2/pull/63

Parser

• Unary plus is now accepted in match literal patterns, mirroring the existing support for unary minus. Our existing parse error should become a version-related syntax error.
  • https://github.com/astral-sh/ruff/pull/28231

Standard library updates

• https://github.com/astral-sh/ruff/issues/21119
  • PEP 814: Add frozendict built-in type
  • PEP 661: Add sentinel built-in type
  • PEP 799: A dedicated profiling package

Other rule changes

• RUF039 and RUF055 should know about re.prefixmatch
  • https://github.com/astral-sh/ruff/pull/28311
• ImportCycleError is incorrectly classified as a 3.13 builtin in PLW0133
  • https://github.com/astral-sh/ruff/pull/28310
• Ruff should recognize slice and frozendict as generic types so their quoted type arguments are analyzed correctly.
  • https://github.com/astral-sh/ruff/pull/28477
  • Python 3.15 language changes, including generic slice
  • PEP 814: Add frozendict built-in type
  • Current code: standard-library generic recognition
• Deprecated typing.no_type_check_decorator() has been removed and should no longer be recommended by UP035
  • https://github.com/astral-sh/ruff/pull/28475
• __cached__ is no longer initialized in Python 3.15 and should only be included in Ruff's magic globals for earlier target versions.
  • https://github.com/astral-sh/ruff/pull/28476
  • Python 3.15 language changes
  • Current code: unconditional magic globals and version-dependent magic globals
• typing.ByteString and collections.abc.ByteString have both been removed from their respective __all__s. It probably makes sense to drop the typing.ByteString -> collections.abc.ByteString recommendation from UP035 as well (but keep the collections.ByteString -> collections.abc.ByteString version, which is still helpful on older versions)
  • https://github.com/astral-sh/ruff/pull/28498
• Ruff should recognize quoted types in TypeForm[...] and TypeForm(...), avoiding false F401 diagnostics.
  • https://github.com/astral-sh/ruff/pull/28507
  • PEP 747: Annotating type forms
  • Current code: generic recognition and typing-call classification
• TypeVarTuple now accepts bound, but UP040, UP046, and UP047 generate invalid syntax such as [*Ts: int]. These conversions should be skipped while the bound's typing semantics remain unspecified.
  • https://github.com/astral-sh/ruff/pull/28505
  • Python 3.15 typing changes
  • Current code: shared PEP 695 type-parameter rendering
• RUF064 should check the new parent_mode argument to os.makedirs and Path.mkdir. PTH103 should preserve it when converting os.makedirs calls to Path.mkdir.
  • https://github.com/astral-sh/ruff/pull/28528
  • Python documentation: os.makedirs and Path.mkdir
  • Current code: permission argument detection and os.makedirs fix validation
• UP013 should preserve the new TypedDict closed and extra_items arguments when converting to class syntax. Quoted types in class-based extra_items arguments should also count as uses of their imports, avoiding false F401 diagnostics.
  • https://github.com/astral-sh/ruff/pull/28533
  • PEP 728: TypedDict with typed extra items
  • Current code: TypedDict conversion and class analysis

Rule stabilizations

• lazy-import-mismatch (TID254)
• lazy-import-immediately-resolved (TID255)
• os-path-commonprefix (RUF071)

Misc

• https://github.com/conda-forge/ruff-feedstock/pull/363
• Bump the language classifier in pyproject.toml
• Update default and latest Python versions
  • 3.10 is reaching EOL
  • See https://github.com/astral-sh/ruff/pull/20725 for last year's bump

Potential lint rules

These shouldn't block the release, but could be interesting.

• https://github.com/astral-sh/ruff/issues/21305

  This primarily tracks additional lints now, with the remaining adjustment to existing rules (point 2) tracked by https://github.com/astral-sh/ruff/issues/25181.

• https://github.com/astral-sh/ruff/issues/24545

• Suggested optimizing refactors around bytearray.take_bytes