v23.7.0

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Highlights

• Runtime support for Python 3.7 has been removed. Formatting 3.7 code will still be
  supported until further notice (#​3765)

Stable style

• Fix a bug where an illegal trailing comma was added to return type annotations using
  PEP 604 unions (#​3735)
• Fix several bugs and crashes where comments in stub files were removed or mishandled
  under some circumstances (#​3745)
• Fix a crash with multi-line magic comments like type: ignore within parentheses
  (#​3740)
• Fix error in AST validation when Black removes trailing whitespace in a type comment
  (#​3773)

Preview style

• Implicitly concatenated strings used as function args are no longer wrapped inside
  parentheses (#​3640)
• Remove blank lines between a class definition and its docstring (#​3692)

Configuration

• The --workers argument to Black can now be specified via the BLACK_NUM_WORKERS
  environment variable (#​3743)
• .pytest_cache, .ruff_cache and .vscode are now excluded by default (#​3691)
• Fix Black not honouring pyproject.toml settings when running --stdin-filename
  and the pyproject.toml found isn't in the current working directory (#​3719)
• Black will now error if exclude and extend-exclude have invalid data types in
  pyproject.toml, instead of silently doing the wrong thing (#​3764)

Packaging

• Upgrade mypyc from 0.991 to 1.3 (#​3697)
• Remove patching of Click that mitigated errors on Python 3.6 with LANG=C (#​3768)

Parser

• Add support for the new PEP 695 syntax in Python 3.12 (#​3703)

Performance

• Speed up Black significantly when the cache is full (#​3751)
• Avoid importing IPython in a case where we wouldn't need it (#​3748)

Output

• Use aware UTC datetimes internally, avoids deprecation warning on Python 3.12 (#​3728)
• Change verbose logging to exactly mirror Black's logic for source discovery (#​3749)

Blackd

• The blackd argument parser now shows the default values for options in their help
  text (#​3712)

Integrations

• Black is now tested with
  PYTHONWARNDEFAULTENCODING = 1
  (#​3763)
• Update GitHub Action to display black output in the job summary (#​3688)

Documentation

• Add a CITATION.cff file to the root of the repository, containing metadata on how to
  cite this software (#​3723)
• Update the classes and exceptions documentation in Developer reference to match
  the latest code base (#​3755)

v23.3.0

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Highlights

This release fixes a longstanding confusing behavior in Black's GitHub action, where the
version of the action did not determine the version of Black being run (issue #​3382). In
addition, there is a small bug fix around imports and a number of improvements to the
preview style.

Please try out the
preview style
with black --preview and tell us your feedback. All changes in the preview style are
expected to become part of Black's stable style in January 2024.

Stable style

• Import lines with # fmt: skip and # fmt: off no longer have an extra blank line
  added when they are right after another import line (#​3610)

Preview style

• Add trailing commas to collection literals even if there's a comment after the last
  entry (#​3393)
• async def, async for, and async with statements are now formatted consistently
  compared to their non-async version. (#​3609)
• with statements that contain two context managers will be consistently wrapped in
  parentheses (#​3589)
• Let string splitters respect East Asian Width
  (#​3445)
• Now long string literals can be split after East Asian commas and periods (、 U+3001
  IDEOGRAPHIC COMMA, 。 U+3002 IDEOGRAPHIC FULL STOP, & ， U+FF0C FULLWIDTH COMMA)
  besides before spaces (#​3445)
• For stubs, enforce one blank line after a nested class with a body other than just
  ... (#​3564)
• Improve handling of multiline strings by changing line split behavior (#​1879)

Parser

• Added support for formatting files with invalid type comments (#​3594)

Integrations

• Update GitHub Action to use the version of Black equivalent to action's version if
  version input is not specified (#​3543)
• Fix missing Python binary path in autoload script for vim (#​3508)

Documentation

• Document that only the most recent release is supported for security issues;
  vulnerabilities should be reported through Tidelift (#​3612)

v23.1.0

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Highlights

This is the first release of 2023, and following our
stability policy,
it comes with a number of improvements to our stable style, including improvements to
empty line handling, removal of redundant parentheses in several contexts, and output
that highlights implicitly concatenated strings better.

There are also many changes to the preview style; try out black --preview and give us
feedback to help us set the stable style for next year.

In addition to style changes, Black now automatically infers the supported Python
versions from your pyproject.toml file, removing the need to set Black's target
versions separately.

Stable style

• Introduce the 2023 stable style, which incorporates most aspects of last year's
  preview style (#​3418). Specific changes:
  • Enforce empty lines before classes and functions with sticky leading comments
    (#​3302) (22.12.0)
  • Reformat empty and whitespace-only files as either an empty file (if no newline is
    present) or as a single newline character (if a newline is present) (#​3348)
    (22.12.0)
  • Implicitly concatenated strings used as function args are now wrapped inside
    parentheses (#​3307) (22.12.0)
  • Correctly handle trailing commas that are inside a line's leading non-nested parens
    (#​3370) (22.12.0)
  • --skip-string-normalization / -S now prevents docstring prefixes from being
    normalized as expected (#​3168) (since 22.8.0)
  • When using --skip-magic-trailing-comma or -C, trailing commas are stripped from
    subscript expressions with more than 1 element (#​3209) (22.8.0)
  • Implicitly concatenated strings inside a list, set, or tuple are now wrapped inside
    parentheses (#​3162) (22.8.0)
  • Fix a string merging/split issue when a comment is present in the middle of
    implicitly concatenated strings on its own line (#​3227) (22.8.0)
  • Docstring quotes are no longer moved if it would violate the line length limit
    (#​3044, #​3430) (22.6.0)
  • Parentheses around return annotations are now managed (#​2990) (22.6.0)
  • Remove unnecessary parentheses around awaited objects (#​2991) (22.6.0)
  • Remove unnecessary parentheses in with statements (#​2926) (22.6.0)
  • Remove trailing newlines after code block open (#​3035) (22.6.0)
  • Code cell separators #%% are now standardised to # %% (#​2919) (22.3.0)
  • Remove unnecessary parentheses from except statements (#​2939) (22.3.0)
  • Remove unnecessary parentheses from tuple unpacking in for loops (#​2945) (22.3.0)
  • Avoid magic-trailing-comma in single-element subscripts (#​2942) (22.3.0)
• Fix a crash when a colon line is marked between # fmt: off and # fmt: on (#​3439)

Preview style

• Format hex codes in unicode escape sequences in string literals (#​2916)
• Add parentheses around if-else expressions (#​2278)
• Improve performance on large expressions that contain many strings (#​3467)
• Fix a crash in preview style with assert + parenthesized string (#​3415)
• Fix crashes in preview style with walrus operators used in function return annotations
  and except clauses (#​3423)
• Fix a crash in preview advanced string processing where mixed implicitly concatenated
  regular and f-strings start with an empty span (#​3463)
• Fix a crash in preview advanced string processing where a standalone comment is placed
  before a dict's value (#​3469)
• Fix an issue where extra empty lines are added when a decorator has # fmt: skip
  applied or there is a standalone comment between decorators (#​3470)
• Do not put the closing quotes in a docstring on a separate line, even if the line is
  too long (#​3430)
• Long values in dict literals are now wrapped in parentheses; correspondingly
  unnecessary parentheses around short values in dict literals are now removed; long
  string lambda values are now wrapped in parentheses (#​3440)
• Fix two crashes in preview style involving edge cases with docstrings (#​3451)
• Exclude string type annotations from improved string processing; fix crash when the
  return type annotation is stringified and spans across multiple lines (#​3462)
• Wrap multiple context managers in parentheses when targeting Python 3.9+ (#​3489)
• Fix several crashes in preview style with walrus operators used in with statements
  or tuples (#​3473)
• Fix an invalid quote escaping bug in f-string expressions where it produced invalid
  code. Implicitly concatenated f-strings with different quotes can now be merged or
  quote-normalized by changing the quotes used in expressions. (#​3509)
• Fix crash on await (yield) when Black is compiled with mypyc (#​3533)

Configuration

• Black now tries to infer its --target-version from the project metadata specified in
  pyproject.toml (#​3219)

Packaging

• Upgrade mypyc from 0.971 to 0.991 so mypycified Black can be built on armv7
  (#​3380)
  • This also fixes some crashes while using compiled Black with a debug build of
    CPython
• Drop specific support for the tomli requirement on 3.11 alpha releases, working
  around a bug that would cause the requirement not to be installed on any non-final
  Python releases (#​3448)
• Black now depends on packaging version 22.0 or later. This is required for new
  functionality that needs to parse part of the project metadata (#​3219)

Output

• Calling black --help multiple times will return the same help contents each time
  (#​3516)
• Verbose logging now shows the values of pyproject.toml configuration variables
  (#​3392)
• Fix false symlink detection messages in verbose output due to using an incorrect
  relative path to the project root (#​3385)

Integrations

• Move 3.11 CI to normal flow now that all dependencies support 3.11 (#​3446)
• Docker: Add new latest_prerelease tag automation to follow latest black alpha
  release on docker images (#​3465)

Documentation

• Expand vim-plug installation instructions to offer more explicit options (#​3468)

v22.12.0

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Preview style

• Enforce empty lines before classes and functions with sticky leading comments (#​3302)
• Reformat empty and whitespace-only files as either an empty file (if no newline is
  present) or as a single newline character (if a newline is present) (#​3348)
• Implicitly concatenated strings used as function args are now wrapped inside
  parentheses (#​3307)
• For assignment statements, prefer splitting the right hand side if the left hand side
  fits on a single line (#​3368)
• Correctly handle trailing commas that are inside a line's leading non-nested parens
  (#​3370)

Configuration

• Fix incorrectly applied .gitignore rules by considering the .gitignore location
  and the relative path to the target file (#​3338)
• Fix incorrectly ignoring .gitignore presence when more than one source directory is
  specified (#​3336)

Parser

• Parsing support has been added for walruses inside generator expression that are
  passed as function args (for example,
  any(match := my_re.match(text) for text in texts)) (#​3327).

Integrations

• Vim plugin: Optionally allow using the system installation of Black via
  let g:black_use_virtualenv = 0(#​3309)

v22.10.0

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Highlights

• Runtime support for Python 3.6 has been removed. Formatting 3.6 code will still be
  supported until further notice.

Stable style

• Fix a crash when # fmt: on is used on a different block level than # fmt: off
  (#​3281)

Preview style

• Fix a crash when formatting some dicts with parenthesis-wrapped long string keys
  (#​3262)

Configuration

• .ipynb_checkpoints directories are now excluded by default (#​3293)
• Add --skip-source-first-line / -x option to ignore the first line of source code
  while formatting (#​3299)

Packaging

• Executables made with PyInstaller will no longer crash when formatting several files
  at once on macOS. Native x86-64 executables for macOS are available once again.
  (#​3275)
• Hatchling is now used as the build backend. This will not have any effect for users
  who install Black with its wheels from PyPI. (#​3233)
• Faster compiled wheels are now available for CPython 3.11 (#​3276)

Blackd

• Windows style (CRLF) newlines will be preserved (#​3257).

Integrations

• Vim plugin: add flag (g:black_preview) to enable/disable the preview style (#​3246)
• Update GitHub Action to support formatting of Jupyter Notebook files via a jupyter
  option (#​3282)
• Update GitHub Action to support use of version specifiers (e.g. <23) for Black
  version (#​3265)

v22.8.0

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Highlights

• Python 3.11 is now supported, except for blackd as aiohttp does not support 3.11 as
  of publishing (#​3234)
• This is the last release that supports running Black on Python 3.6 (formatting 3.6
  code will continue to be supported until further notice)
• Reword the stability policy to say that we may, in rare cases, make changes that
  affect code that was not previously formatted by Black (#​3155)

Stable style

• Fix an infinite loop when using # fmt: on/off in the middle of an expression or code
  block (#​3158)
• Fix incorrect handling of # fmt: skip on colon (:) lines (#​3148)
• Comments are no longer deleted when a line had spaces removed around power operators
  (#​2874)

Preview style

• Single-character closing docstring quotes are no longer moved to their own line as
  this is invalid. This was a bug introduced in version 22.6.0. (#​3166)
• --skip-string-normalization / -S now prevents docstring prefixes from being
  normalized as expected (#​3168)
• When using --skip-magic-trailing-comma or -C, trailing commas are stripped from
  subscript expressions with more than 1 element (#​3209)
• Implicitly concatenated strings inside a list, set, or tuple are now wrapped inside
  parentheses (#​3162)
• Fix a string merging/split issue when a comment is present in the middle of implicitly
  concatenated strings on its own line (#​3227)

Blackd

• blackd now supports enabling the preview style via the X-Preview header (#​3217)

Configuration

• Black now uses the presence of debug f-strings to detect target version (#​3215)
• Fix misdetection of project root and verbose logging of sources in cases involving
  --stdin-filename (#​3216)
• Immediate .gitignore files in source directories given on the command line are now
  also respected, previously only .gitignore files in the project root and
  automatically discovered directories were respected (#​3237)

Documentation

• Recommend using BlackConnect in IntelliJ IDEs (#​3150)

Integrations

• Vim plugin: prefix messages with Black: so it's clear they come from Black (#​3194)
• Docker: changed to a /opt/venv installation + added to PATH to be available to
  non-root users (#​3202)

Output

• Change from deprecated asyncio.get_event_loop() to create our event loop which
  removes DeprecationWarning (#​3164)
• Remove logging from internal blib2to3 library since it regularly emits error logs
  about failed caching that can and should be ignored (#​3193)

Parser

• Type comments are now included in the AST equivalence check consistently so accidental
  deletion raises an error. Though type comments can't be tracked when running on PyPy
  3.7 due to standard library limitations. (#​2874)

Performance

• Reduce Black's startup time when formatting a single file by 15-30% (#​3211)

v22.6.0

Compare Source

Style

• Fix unstable formatting involving #fmt: skip and # fmt:skip comments (notice the
  lack of spaces) (#​2970)

Preview style

• Docstring quotes are no longer moved if it would violate the line length limit (#​3044)
• Parentheses around return annotations are now managed (#​2990)
• Remove unnecessary parentheses around awaited objects (#​2991)
• Remove unnecessary parentheses in with statements (#​2926)
• Remove trailing newlines after code block open (#​3035)

Integrations

• Add scripts/migrate-black.py script to ease introduction of Black to a Git project
  (#​3038)

Output

• Output Python version and implementation as part of --version flag (#​2997)

Packaging

• Use tomli instead of tomllib on Python 3.11 builds where tomllib is not
  available (#​2987)

Parser

• PEP 654 syntax (for example,
  except *ExceptionGroup:) is now supported (#​3016)
• PEP 646 syntax (for example,
  Array[Batch, *Shape] or def fn(*args: *T) -> None) is now supported (#​3071)

Vim Plugin

• Fix strtobool function. It didn't parse true/on/false/off. (#​3025)

v22.3.0

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Preview style

• Code cell separators #%% are now standardised to # %% (#​2919)
• Remove unnecessary parentheses from except statements (#​2939)
• Remove unnecessary parentheses from tuple unpacking in for loops (#​2945)
• Avoid magic-trailing-comma in single-element subscripts (#​2942)

Configuration

• Do not format __pypackages__ directories by default (#​2836)
• Add support for specifying stable version with --required-version (#​2832).
• Avoid crashing when the user has no homedir (#​2814)
• Avoid crashing when md5 is not available (#​2905)
• Fix handling of directory junctions on Windows (#​2904)

Documentation

• Update pylint config documentation (#​2931)

Integrations

• Move test to disable plugin in Vim/Neovim, which speeds up loading (#​2896)

Output

• In verbose mode, log when Black is using user-level config (#​2861)

Packaging

• Fix Black to work with Click 8.1.0 (#​2966)
• On Python 3.11 and newer, use the standard library's tomllib instead of tomli
  (#​2903)
• black-primer, the deprecated internal devtool, has been removed and copied to a
  separate repository (#​2924)

Parser

• Black can now parse starred expressions in the target of for and async for
  statements, e.g for item in *items_1, *items_2: pass (#​2879).

v22.1.0

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At long last, Black is no longer a beta product! This is the first non-beta release
and the first release covered by our new
stability policy.

Highlights

• Remove Python 2 support (#​2740)
• Introduce the --preview flag (#​2752)

Style

• Deprecate --experimental-string-processing and move the functionality under
  --preview (#​2789)
• For stubs, one blank line between class attributes and methods is now kept if there's
  at least one pre-existing blank line (#​2736)
• Black now normalizes string prefix order (#​2297)
• Remove spaces around power operators if both operands are simple (#​2726)
• Work around bug that causes unstable formatting in some cases in the presence of the
  magic trailing comma (#​2807)
• Use parentheses for attribute access on decimal float and int literals (#​2799)
• Don't add whitespace for attribute access on hexadecimal, binary, octal, and complex
  literals (#​2799)
• Treat blank lines in stubs the same inside top-level if statements (#​2820)
• Fix unstable formatting with semicolons and arithmetic expressions (#​2817)
• Fix unstable formatting around magic trailing comma (#​2572)

Parser

• Fix mapping cases that contain as-expressions, like case {"key": 1 | 2 as password}
  (#​2686)
• Fix cases that contain multiple top-level as-expressions, like case 1 as a, 2 as b
  (#​2716)
• Fix call patterns that contain as-expressions with keyword arguments, like
  case Foo(bar=baz as quux) (#​2749)
• Tuple unpacking on return and yield constructs now implies 3.8+ (#​2700)
• Unparenthesized tuples on annotated assignments (e.g
  values: Tuple[int, ...] = 1, 2, 3) now implies 3.8+ (#​2708)
• Fix handling of standalone match() or case() when there is a trailing newline or a
  comment inside of the parentheses. (#​2760)
• from __future__ import annotations statement now implies Python 3.7+ (#​2690)

Performance

• Speed-up the new backtracking parser about 4X in general (enabled when
  --target-version is set to 3.10 and higher). (#​2728)
• Black is now compiled with mypyc for an overall 2x
  speed-up. 64-bit Windows, MacOS, and Linux (not including musl) are supported. (#​1009,
  #​2431)

Configuration

• Do not accept bare carriage return line endings in pyproject.toml (#​2408)
• Add configuration option (python-cell-magics) to format cells with custom magics in
  Jupyter Notebooks (#​2744)
• Allow setting custom cache directory on all platforms with environment variable
  BLACK_CACHE_DIR (#​2739).
• Enable Python 3.10+ by default, without any extra need to specify
  --target-version=py310. (#​2758)
• Make passing SRC or --code mandatory and mutually exclusive (#​2804)

Output

• Improve error message for invalid regular expression (#​2678)
• Improve error message when parsing fails during AST safety check by embedding the
  underlying SyntaxError (#​2693)
• No longer color diff headers white as it's unreadable in light themed terminals
  (#​2691)
• Text coloring added in the final statistics (#​2712)
• Verbose mode also now describes how a project root was discovered and which paths will
  be formatted. (#​2526)

Packaging

• All upper version bounds on dependencies have been removed (#​2718)
• typing-extensions is no longer a required dependency in Python 3.10+ (#​2772)
• Set click lower bound to 8.0.0 (#​2791)

Integrations

• Update GitHub action to support containerized runs (#​2748)

Documentation

• Change protocol in pip installation instructions to https:// (#​2761)
• Change HTML theme to Furo primarily for its responsive design and mobile support
  (#​2793)
• Deprecate the black-primer tool (#​2809)
• Document Python support policy (#​2819)