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)