Repository navigation
Avoid unnecessary parens for unbreakable RHS in assignments (#3954) - #5473
Merged
Merged
Conversation
Prateek99-s
force-pushed
the
fix-annotated-string-parens-3954
branch
from
October 3, 2026 04:48
06f32dc to
cc6265b
Compare
Contributor
|
diff-shades results comparing this PR (1e5b9aa) to main (30664d8):
|
Prateek99-s
force-pushed
the
fix-annotated-string-parens-3954
branch
from
October 3, 2026 05:15
cc6265b to
ffbec9b
Compare
cobaltt7
reviewed
Oct 3, 2026
Prateek99-s
force-pushed
the
fix-annotated-string-parens-3954
branch
from
October 4, 2026 14:46
ffbec9b to
dc9febd
Compare
Contributor
Author
|
Done! Added a standard assignment to the example for direct comparison |
Prateek99-s
force-pushed
the
fix-annotated-string-parens-3954
branch
from
October 4, 2026 16:14
dc9febd to
2a389be
Compare
luketainton
pushed a commit
to luketainton/luke_instant-msg-api
that referenced
this pull request
Oct 10, 2026
![renovate[bot]](https://github.githubassets.com/images/gravatars/gravatar-user-420.png){kind=avatar}
This PR contains the following updates: | Package | Change | [Age](https://docs.renovatebot.com/merge-confidence/) | [Confidence](https://docs.renovatebot.com/merge-confidence/) | |---|---|---|---| | [black](https://github.com/psf/black) ([changelog](https://github.com/psf/black/blob/main/CHANGES.md)) | `<26.10.1,>=26.10.0` → `<26.10.2,>=26.10.1` |  |  | --- ### Release Notes <details> <summary>psf/black (black)</summary> ### [`v26.10.1`](https://github.com/psf/black/blob/HEAD/CHANGES.md#Version-26101) [Compare Source](psf/black@26.10.0...26.10.1) ##### Highlights This release fixes a security issue in Black's bundled GitHub Action. Repositories that use the action are encouraged to update to the latest version of Black immediately. This update is received automatically when using `psf/black@stable`, and is independent of the version of Black installed by the action. When the GitHub Action reads version specifiers from `tool.black.required-version`, it now only accepts released versions of Black, as it already did for `black` requirements in dependency lists. Other values, such as URL references, are now rejected. This issue has been registered as `GHSA-cg8m-r9f2-5wm2`; a CVE identifier is pending. ##### Stable style - Fix a long Jupyter notebook assignment magic (for example `x = !ls -la`) being wrapped in parentheses, which IPython can no longer run; such cells are now left unchanged ([#​5481](psf/black#5481)) - Keep repeated lines outside the selected `--line-ranges` unchanged ([#​5436](psf/black#5436)) - Fix `--line-ranges` formatting lines that follow a statement when formatting joins or re-indents that statement ([#​5484](psf/black#5484)) - Fix `--line-ranges` crashing with an internal error when an unselected statement has a `# fmt: skip` comment on the last line before a closing bracket ([#​5477](psf/black#5477)) - Prevent moving an encoding declaration (for example `# -*- coding: latin-1 -*-`) onto the first two lines of a file ([#​5487](psf/black#5487)) - Fix adding an extra trailing blank line inside a multi-line module docstring when its last line is near the line length limit ([#​5494](psf/black#5494)) ##### Preview style - Do not split short expressions on delimiters (such as binary operators, comparisons, or comprehensions) inside brackets when preceded by a standalone comment ([#​5455](psf/black#5455)) - Fix the unstable `string_processing` feature removing backslash-newline sequences from raw strings, which changed their value ([#​5482](psf/black#5482)) - Avoid adding unnecessary parentheses around unbreakable right-hand side expressions in assignments (such as annotated assignments or subscript targets) ([#​5473](psf/black#5473)) - Parenthesize expressions with parameter comments when they exceed the line length under `--preview` ([#​5442](psf/black#5442)) - Fix `wrap_long_dict_values_in_parens` dropping the parentheses around a right-hand side that contains a dictionary, leaving a line over the length limit ([#​5492](psf/black#5492)) - Fix the unstable `string_processing` feature adding a space after `*` or `**` in a PEP 695 type parameter (`* Ts = ...`) when it splits a string in the parameter's default ([#​5504](psf/black#5504)) - Avoid unnecessary line splits of trailers (such as indexing/subscripts) when an earlier bracket split exceeds the line length only due to a trailing comment ([#​5498](psf/black#5498)) ##### Configuration - Add `--cache-dir` to configure the cache directory from the command line ([#​5433](psf/black#5433)) - Don't cache a file as formatted after formatting or checking it with `--line-ranges`, which made a later full `black --check` pass and `black` skip the unformatted lines ([#​5476](psf/black#5476)) - Respect a `.gitignore` that starts with a UTF-8 byte order mark. The mark became part of the first pattern, so that pattern never matched and Black formatted files that git ignores ([#​5497](psf/black#5497)) ##### Performance - Avoid quadratic runtime when splitting very long lines with many trailing bracket pairs (such as consecutive subscripts) ([#​5475](psf/black#5475)) ##### Integrations - Fix the GitHub Action crashing on dependency-group includes when `use_pyproject` is enabled ([#​5479](psf/black#5479)) - When the GitHub Action reads version specifiers from `tool.black.required-version`, it now only accepts released versions of Black, as it already did for `black` requirements in dependency lists. Other values, such as URL references, are now rejected. ([#​5510](psf/black#5510)) </details> --- ### Configuration 📅 **Schedule**: (UTC) - Branch creation - At any time (no schedule defined) - Automerge - At any time (no schedule defined) 🚦 **Automerge**: Enabled. ♻ **Rebasing**: Whenever PR is behind base branch, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this PR and you won't be reminded about this update again. --- - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box --- This PR has been generated by [Mend Renovate CLI](https://github.com/renovatebot/renovate). <!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiI0NC4xNDkuMCIsInVwZGF0ZWRJblZlciI6IjQ0LjE0OS4wIiwidGFyZ2V0QnJhbmNoIjoibWFpbiIsImxhYmVscyI6WyJ0eXBlL2RlcGVuZGVuY2llcyJdfQ==--> Reviewed-on: https://git.tainton.uk/luke/instant-msg-api/pulls/292 Co-authored-by: renovate[bot] <renovate-bot@git.tainton.uk>
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Fixes #3954
Summary
When an assignment's target contains type
annotations or brackets (e.g.
attr: str = "long..."or
a[0] = "long...") and the RHSis an unbreakable expression (like a long
string or identifier) that cannot fit within
the line length limit even with parentheses,
Black previously wrapped the RHS in outer
parentheses, creating an inconsistency with
standard unannotated assignments (
attr = "long...").This happened because
_maybe_split_omitting_optional_parensfoundan alternative split on the LHS
brackets/invisible parens (
rhs_oop), rejectedit via
_prefer_split_rhs_oop_over_rhs, butthen bypassed the validation check that
verifies whether the original RHS body can
actually be split or fit on one line.
Under
--preview, Black now recognizes thatthe alternative split was rejected and falls
back to validating the original RHS, leaving
unbreakable expressions unparenthesized when
wrapping cannot satisfy the line length.