black 26.10.0

on Python PyPI

Stable style

• --line-ranges no longer inserts an empty line after a docstring when the range
  covers only the docstring itself (#5312)
• Fix # fmt: skip on a bracketed ternary turning the surrounding tuple into a call
  (#5464)
• Fix crash when # fmt: skip is placed on a one-line function or class with PEP 695
  type parameters (#5429)
• Fix an inline comment after the closing bracket of optional parentheses being moved
  inside the parentheses when the parenthesized expression contains own-line comments
  (#5395)
• Fix unparseable output when # fmt: skip is placed on a bracket of an if, while,
  for, or with header (#5401, #5405)
• Fix crash when formatting parenthesized expressions with multiple inline comments and
  # fmt: skip (#5414)
• Fix parsing Jupyter notebook assignment magics when non-ASCII characters appear
  earlier on the line (#5381)
• Preserve blank lines that come immediately before a # fmt: on comment (#5300)
• Keep the parentheses around the target of an annotated assignment (e.g.
  (x): int = 5), which prevent CPython from including the name in __annotations__
  (#5321)
• Stop treating a t-string in docstring position as a docstring (e.g. t" spam " as
  the first statement of a module, class or function) (#5287)
• Fix unparseable output for a t-string whose replacement field contains a quote (e.g.
  t'\'{a["b"]}\'') (#5265)
• Fix unparseable output for a triple-quoted string whose body ends in an
  already-escaped double quote (e.g. '''\'''\"''') (#5262)
• Fix --skip-magic-trailing-comma dropping the trailing comma from a split
  single-element tuple used as a lambda parameter default (#5246)
• Fix unstable formatting when an inline comment sits on optional parentheses (e.g. a
  parenthesized assert message) (#5241)
• Fix --skip-magic-trailing-comma dropping the trailing comma of a one-element
  subscript (a[x,]) when the line is long enough to be split and contains a power
  operator (#5272)
• Fix crash when a standalone comment sits between tokens of a comprehension or lambda
  (#5144)
• Fix inline comments on a bracket inside a comprehension being dropped (#5330)
• Respect the magic trailing comma in a PEP 695 type parameter list containing a
  *TypeVarTuple or **ParamSpec (#5244)
• Fix crash when a comment-only # fmt: off/# fmt: on block is followed by a with
  statement after another standalone comment (#5189)
• Fix a crash when splitting case case if ... match patterns at very small line
  lengths (#5147)
• Fix multiline docstring indentation when leading tabs are used inside indented
  docstrings (#5148)
• Respect # fmt: skip on a line that opens a bracket (e.g.
  from x import ( # fmt: skip) when a standalone comment is among the bracket's
  contents (#5161)
• Fix an AST safety error when separate # type: ignore comments in a parenthesized
  attribute chain were merged onto one physical line (#5297)
• Preserve comments and blank lines outside requested ranges when formatting with
  --line-ranges (#5175)
• Fix crash when # fmt: skip is used on one-line async def, async with, and
  async for statements containing a semicolon (#5311)
• Stop converting form feeds or other similar characters in docstrings into newlines
  (#5461)
• Fix --skip-source-first-line turning the skipped line's CRLF ending into \r\r\n
  when reformatting a file with CRLF line endings (#5438)

Preview style

New preview features

• Add missing blank lines after classes whose last method has an ellipsis body (#5439)
• Split only the brackets holding a magic trailing comma when more trailers follow them
  (e.g. stop splitting inside the [2] of [1,][2](3)) (#5448)
• Keep dictionary keys containing operators together on one line when the value can be
  wrapped onto a new line instead (#5435)
• Remove redundant parentheses around individual variables in unpacking targets (e.g.
  for (x), (y) in points: becomes for x, y in points:) (#5416)
• Normalize uppercase T prefixes on t-strings to lowercase (#5425)
• Remove redundant parentheses around generator expressions (#5304, #5369)
• Preserve two blank lines before a top-level class starting inside a # fmt: off block
  after an import (#5238)
• Fix unnecessary parentheses around short right-hand expressions in indexed assignments
  (e.g. x[key] = expr) (#5095)
• Parenthesize tuple expressions in yield statements for consistency with function
  calls and returns (#5170)
• Stop splitting between a variable and its operator (not in, ==, is, ...) when
  the right-hand side is a bracketed expression, and instead split inside the brackets
  (#5135)
• In .pyi stub files, enforce a blank line after a function or method that has a
  docstring-only body when another comment or statement follows it (#5158)

Updates to existing preview features

• Fix crash in stub files when # fmt: skip is placed on a function in a group of
  same-name decorated functions (e.g. @overloads or a property setter) (#5430)
• Keep the parentheses around a lambda used as the iterable of a comprehension (e.g.
  [x for x in (lambda: 0) if x]) (#5176, #5200)

Updates to existing unstable features

• Do not treat multi-line expressions with merged strings and trailing # type: ignore
  comments as single-line unsplittable expressions (#5466)
• Fix duplicated inline comment when stripping the parentheses around a string or
  merging a backslash-continued string on the same line (#5449)
• Split long stringified return annotations even when the function has parameters
  (#5427)
• Don't hug brackets when doing so would join two # type: ignore comments onto one
  line (#5271)
• Fix a crash when # type: ignore is lost during formatting of a long parenthesized
  string (#5329)
• Fix only the first part of an implicitly concatenated unmergeable string (e.g.
  r"..." r"...") being wrapped in parentheses (#5434)

Configuration

• Add support for NO_COLOR environment variable to disable ANSI output (#5129)
• Remove spurious target version warning when runtime version is included in a
  --target-version flag (#5167)
• Fix --force-exclude not excluding files whose path contains .. (e.g.
  black ../generated/file.py run from a subdirectory) (#5471)
• Fall back to the default configuration, with a warning, when the given sources share
  no common project root (e.g. they are on different drives on Windows) instead of
  crashing (#5386)
• Fix loading a stale cached pyproject.toml path when --code is used from different
  working directories in the same process (#5152)
• Add validation for --line-ranges values (#5107)
• Ignore empty cache files instead of raising an EOFError (#5192)
• Reject non-string include and force-exclude values in pyproject.toml (#5193)
• Validate BLACK_NUM_WORKERS values and report invalid values as usage errors instead
  of crashing (#5211)
• Ignore permission errors when reading cache (#5258)

Packaging

• Reduce the size of Linux standalone binaries by stripping debug symbols during the
  PyInstaller release build (#5223)
• Black is now released using GitHub
  Immutable Releases
  (#5296)

Performance

• Fix superlinear runtime growth with the number of input files (#5450)
• Improve performance on strings containing many consecutive backslashes (#5163)
• Improve performance on files with many # fmt: skip/# fmt: off/# fmt: on comments
  (#5169, #5190, #5232)
• Improve performance on long calls and collections (#5177)
• Improve performance on multiline strings inside large collections (e.g. a dict literal
  with triple-quoted strings as values) (#5188)
• Improve performance on files with many soft keywords (e.g. match/case blocks)
  (#5186)
• Improve performance on long semicolon-separated statements (in the stable style) and
  large dict literals (in --preview) (#5184)
• Improve performance of --line-ranges on files with many sibling blocks (a long
  if/elif chain, a match with many cases, or many top-level definitions) (#5213)
• Improve performance on deeply nested bracketed expressions (#5171, #5242)
• Improve performance on lists and subscripts holding one long expression without
  operators (e.g. a long run of implicitly concatenated strings inside []) (#5239)
• Improve performance on deeply chained operations (e.g. a long a ** b ** c ** ...
  chain) (#5235)
• Improve performance on long if/elif chains and other compound statements with many
  clauses (#5322)
• Improve performance of string_processing:
  • when merging implicitly concatenated f-strings containing long string literals
    (#5165)
  • when merging long implicitly concatenated strings (#5173, #5194)
  • when rewriting large nodes (e.g. "%s ..." % (a, b, c, ...)) (#5178, #5199, #5220)
  • when splitting long string literals (#5183)

Output

• Report parser failures using editor-friendly path:line:column locations (#5237)
• Fix crash when writing formatted code or diffs to a sys.stdout that has no buffer
  attribute (e.g. in Jupyter notebooks) (#5411)
• Report parse failures on Black's own output as internal errors (#5383)

Blackd

• Return HTTP 400 instead of 500 when the X-Python-Variant header is empty or has an
  empty entry (e.g. a trailing comma) (#5428)
• Allow optional whitespace around comma-separated versions and pyi in the
  X-Python-Variant header (#5441)

Integrations

• Remove unused migrate-black script (#5319)
• Support PEP 440 version specifiers in tool.black.required-version for the GitHub
  Action (#5399)
• Add outputs (is_formatted, change_count, same_count, failure_count) to GitHub
  Action runs (#5408)

Documentation

• Document vim-python-pep8-indent, which provides an indentexpr for Black-style
  insert-mode indentation (#5288)