Fix crash on standalone comment in lambda default arguments by worksbyfriday · Pull Request #4993 · psf/black

worksbyfriday · 2026-02-17T13:57:58Z

Summary

Fixes Standalone comment within parentheses in lambda default arguments crashes black #4640
Closes Fix bug with standalone comments in lambda default arguments #4658
Black crashes with "Opening paren not found in 'leaves'" when a standalone comment appears inside parentheses in a lambda default argument with a trailing comma
Root cause: after line splitting, the opening bracket ends up in a different Line object than the closing bracket, so is_one_sequence_between() can't find it via identity comparison in the current line's leaves

Fix

Return False instead of raising LookupError when the opening bracket isn't found in the leaves list. This is the correct conservative answer — if we can't find both brackets in the same line, we can't determine the sequence between them, so we shouldn't assume it's a one-sequence.

Reproduction

# This crashes Black:
help(lambda x=(
    # comment
    "bar",
): False)

Test plan

Verified both reproduction cases from Standalone comment within parentheses in lambda default arguments crashes black #4640 now format correctly
All 393 existing tests pass (3 skipped, 4 subtests passed)

🤖 Generated with Claude Code

When a standalone comment appears inside parentheses in a lambda default argument with a trailing comma, is_one_sequence_between() raised LookupError because the opening bracket was in a different Line object than the closing bracket after line splitting. Return False instead of raising when the opening bracket isn't found in the leaves list, since we can't determine the sequence relationship when brackets span different lines. Fixes psf#4640 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

JelleZijlstra · 2026-02-20T04:09:29Z

Please add a unit test for this behavior.

github-actions · 2026-02-20T04:23:35Z

diff-shades results comparing this PR (03b89de) to main (ff094ac):

--preview style: no changes

--stable style: no changes

What is this? | Workflow run | diff-shades documentation

Adds a test case for standalone comments in lambda default arguments that previously caused a LookupError crash (fixes psf#4640). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

worksbyfriday · 2026-02-20T15:16:15Z

The test was added in commit 2fdde64 — tests/data/cases/comments_in_lambda_default.py covers both reproduction cases from #4640. It's auto-discovered by test_simple_format and passes:

tests/test_format.py::test_simple_format[comments_in_lambda_default] PASSED

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com> Co-authored-by: cobalt <61329810+cobaltt7@users.noreply.github.com>

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)) | `<26.1.1,>=26.1.0` → `<26.3.1,>=26.3.0` | ![age](https://developer.mend.io/api/mc/badges/age/pypi/black/26.3.0?slim=true) | ![confidence](https://developer.mend.io/api/mc/badges/confidence/pypi/black/26.1.0/26.3.0?slim=true) | --- ### Release Notes <details> <summary>psf/black (black)</summary> ### [`v26.3.0`](https://github.com/psf/black/blob/HEAD/CHANGES.md#2630) [Compare Source](psf/black@26.1.0...26.3.0) ##### Stable style - Don't double-decode input, causing non-UTF-8 files to be corrupted ([#4964](psf/black#4964)) - Fix crash on standalone comment in lambda default arguments ([#4993](psf/black#4993)) - Preserve parentheses when `# type: ignore` comments would be merged with other comments on the same line, preventing AST equivalence failures ([#4888](psf/black#4888)) ##### Preview style - Fix bug where `if` guards in `case` blocks were incorrectly split when the pattern had a trailing comma ([#4884](psf/black#4884)) - Fix `string_processing` crashing on unassigned long string literals with trailing commas (one-item tuples) ([#4929](psf/black#4929)) - Simplify implementation of the power operator "hugging" logic ([#4918](psf/black#4918)) ##### Packaging - Fix shutdown errors in PyInstaller builds on macOS by disabling multiprocessing in frozen environments ([#4930](psf/black#4930)) ##### Performance - Introduce winloop for windows as an alternative to uvloop ([#4996](psf/black#4996)) - Remove deprecated function `uvloop.install()` in favor of `uvloop.new_event_loop()` ([#4996](psf/black#4996)) - Rename `maybe_install_uvloop` function to `maybe_use_uvloop` to simplify loop installation and creation of either a uvloop/winloop evenloop or default eventloop ([#4996](psf/black#4996)) ##### Output - Emit a clear warning when the target Python version is newer than the running Python version, since AST safety checks cannot parse newer syntax. Also replace the misleading "INTERNAL ERROR" message with an actionable error explaining the version mismatch ([#4983](psf/black#4983)) ##### *Blackd* - Introduce winloop to be used when windows in use which enables blackd to run faster on windows when winloop is installed. ([#4996](psf/black#4996)) ##### Integrations - Remove unused gallery script ([#5030](psf/black#5030)) - Harden parsing of `black` requirements in the GitHub Action when `use_pyproject` is enabled so that only version specifiers are accepted and direct references such as `black @ https://...` are rejected. Users should upgrade to the latest version of the action as soon as possible. This update is received automatically when using `psf/black@stable`, and is independent of the version of Black installed by the action. ([#5031](psf/black#5031)) ##### Documentation - Expand preview style documentation with detailed examples for `wrap_comprehension_in`, `simplify_power_operator_hugging`, and `wrap_long_dict_values_in_parens` features ([#4987](psf/black#4987)) - Add detailed documentation for formatting Jupyter Notebooks ([#5009](psf/black#5009)) </details> --- ### Configuration 📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **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. --- - [ ] If you want to rebase/retry this PR, check this box --- This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).  Reviewed-on: https://git.tainton.uk/repos/webexmemebot/pulls/571 Co-authored-by: renovate[bot] <renovate-bot@git.tainton.uk> Co-committed-by: renovate[bot] <renovate-bot@git.tainton.uk>

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)) | `<26.1.1,>=26.1.0` → `<26.3.1,>=26.3.0` | ![age](https://developer.mend.io/api/mc/badges/age/pypi/black/26.3.0?slim=true) | ![confidence](https://developer.mend.io/api/mc/badges/confidence/pypi/black/26.1.0/26.3.0?slim=true) | --- ### Release Notes <details> <summary>psf/black (black)</summary> ### [`v26.3.0`](https://github.com/psf/black/blob/HEAD/CHANGES.md#2630) [Compare Source](psf/black@26.1.0...26.3.0) ##### Stable style - Don't double-decode input, causing non-UTF-8 files to be corrupted ([#4964](psf/black#4964)) - Fix crash on standalone comment in lambda default arguments ([#4993](psf/black#4993)) - Preserve parentheses when `# type: ignore` comments would be merged with other comments on the same line, preventing AST equivalence failures ([#4888](psf/black#4888)) ##### Preview style - Fix bug where `if` guards in `case` blocks were incorrectly split when the pattern had a trailing comma ([#4884](psf/black#4884)) - Fix `string_processing` crashing on unassigned long string literals with trailing commas (one-item tuples) ([#4929](psf/black#4929)) - Simplify implementation of the power operator "hugging" logic ([#4918](psf/black#4918)) ##### Packaging - Fix shutdown errors in PyInstaller builds on macOS by disabling multiprocessing in frozen environments ([#4930](psf/black#4930)) ##### Performance - Introduce winloop for windows as an alternative to uvloop ([#4996](psf/black#4996)) - Remove deprecated function `uvloop.install()` in favor of `uvloop.new_event_loop()` ([#4996](psf/black#4996)) - Rename `maybe_install_uvloop` function to `maybe_use_uvloop` to simplify loop installation and creation of either a uvloop/winloop evenloop or default eventloop ([#4996](psf/black#4996)) ##### Output - Emit a clear warning when the target Python version is newer than the running Python version, since AST safety checks cannot parse newer syntax. Also replace the misleading "INTERNAL ERROR" message with an actionable error explaining the version mismatch ([#4983](psf/black#4983)) ##### *Blackd* - Introduce winloop to be used when windows in use which enables blackd to run faster on windows when winloop is installed. ([#4996](psf/black#4996)) ##### Integrations - Remove unused gallery script ([#5030](psf/black#5030)) - Harden parsing of `black` requirements in the GitHub Action when `use_pyproject` is enabled so that only version specifiers are accepted and direct references such as `black @ https://...` are rejected. Users should upgrade to the latest version of the action as soon as possible. This update is received automatically when using `psf/black@stable`, and is independent of the version of Black installed by the action. ([#5031](psf/black#5031)) ##### Documentation - Expand preview style documentation with detailed examples for `wrap_comprehension_in`, `simplify_power_operator_hugging`, and `wrap_long_dict_values_in_parens` features ([#4987](psf/black#4987)) - Add detailed documentation for formatting Jupyter Notebooks ([#5009](psf/black#5009)) </details> --- ### Configuration 📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **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. --- - [ ] If you want to rebase/retry this PR, check this box --- This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).  Reviewed-on: https://git.tainton.uk/repos/pypilot/pulls/421 Reviewed-by: Luke Tainton <luke@tainton.uk> Co-authored-by: renovate[bot] <renovate-bot@git.tainton.uk> Co-committed-by: renovate[bot] <renovate-bot@git.tainton.uk>

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)) | `<26.1.1,>=26.1.0` → `<26.3.1,>=26.3.0` | ![age](https://developer.mend.io/api/mc/badges/age/pypi/black/26.3.0?slim=true) | ![confidence](https://developer.mend.io/api/mc/badges/confidence/pypi/black/26.1.0/26.3.0?slim=true) | --- ### Release Notes <details> <summary>psf/black (black)</summary> ### [`v26.3.0`](https://github.com/psf/black/blob/HEAD/CHANGES.md#2630) [Compare Source](psf/black@26.1.0...26.3.0) ##### Stable style - Don't double-decode input, causing non-UTF-8 files to be corrupted ([#4964](psf/black#4964)) - Fix crash on standalone comment in lambda default arguments ([#4993](psf/black#4993)) - Preserve parentheses when `# type: ignore` comments would be merged with other comments on the same line, preventing AST equivalence failures ([#4888](psf/black#4888)) ##### Preview style - Fix bug where `if` guards in `case` blocks were incorrectly split when the pattern had a trailing comma ([#4884](psf/black#4884)) - Fix `string_processing` crashing on unassigned long string literals with trailing commas (one-item tuples) ([#4929](psf/black#4929)) - Simplify implementation of the power operator "hugging" logic ([#4918](psf/black#4918)) ##### Packaging - Fix shutdown errors in PyInstaller builds on macOS by disabling multiprocessing in frozen environments ([#4930](psf/black#4930)) ##### Performance - Introduce winloop for windows as an alternative to uvloop ([#4996](psf/black#4996)) - Remove deprecated function `uvloop.install()` in favor of `uvloop.new_event_loop()` ([#4996](psf/black#4996)) - Rename `maybe_install_uvloop` function to `maybe_use_uvloop` to simplify loop installation and creation of either a uvloop/winloop evenloop or default eventloop ([#4996](psf/black#4996)) ##### Output - Emit a clear warning when the target Python version is newer than the running Python version, since AST safety checks cannot parse newer syntax. Also replace the misleading "INTERNAL ERROR" message with an actionable error explaining the version mismatch ([#4983](psf/black#4983)) ##### *Blackd* - Introduce winloop to be used when windows in use which enables blackd to run faster on windows when winloop is installed. ([#4996](psf/black#4996)) ##### Integrations - Remove unused gallery script ([#5030](psf/black#5030)) - Harden parsing of `black` requirements in the GitHub Action when `use_pyproject` is enabled so that only version specifiers are accepted and direct references such as `black @ https://...` are rejected. Users should upgrade to the latest version of the action as soon as possible. This update is received automatically when using `psf/black@stable`, and is independent of the version of Black installed by the action. ([#5031](psf/black#5031)) ##### Documentation - Expand preview style documentation with detailed examples for `wrap_comprehension_in`, `simplify_power_operator_hugging`, and `wrap_long_dict_values_in_parens` features ([#4987](psf/black#4987)) - Add detailed documentation for formatting Jupyter Notebooks ([#5009](psf/black#5009)) </details> --- ### Configuration 📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **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. --- - [ ] If you want to rebase/retry this PR, check this box --- This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).  Reviewed-on: https://git.tainton.uk/luke/instant-msg-api/pulls/246 Reviewed-by: Luke Tainton <luke@tainton.uk> Co-authored-by: renovate[bot] <renovate-bot@git.tainton.uk> Co-committed-by: renovate[bot] <renovate-bot@git.tainton.uk>

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)) | `<26.1.1,>=26.1.0` → `<26.3.1,>=26.3.0` | ![age](https://developer.mend.io/api/mc/badges/age/pypi/black/26.3.0?slim=true) | ![confidence](https://developer.mend.io/api/mc/badges/confidence/pypi/black/26.1.0/26.3.0?slim=true) | --- ### Release Notes <details> <summary>psf/black (black)</summary> ### [`v26.3.0`](https://github.com/psf/black/blob/HEAD/CHANGES.md#2630) [Compare Source](psf/black@26.1.0...26.3.0) ##### Stable style - Don't double-decode input, causing non-UTF-8 files to be corrupted ([#4964](psf/black#4964)) - Fix crash on standalone comment in lambda default arguments ([#4993](psf/black#4993)) - Preserve parentheses when `# type: ignore` comments would be merged with other comments on the same line, preventing AST equivalence failures ([#4888](psf/black#4888)) ##### Preview style - Fix bug where `if` guards in `case` blocks were incorrectly split when the pattern had a trailing comma ([#4884](psf/black#4884)) - Fix `string_processing` crashing on unassigned long string literals with trailing commas (one-item tuples) ([#4929](psf/black#4929)) - Simplify implementation of the power operator "hugging" logic ([#4918](psf/black#4918)) ##### Packaging - Fix shutdown errors in PyInstaller builds on macOS by disabling multiprocessing in frozen environments ([#4930](psf/black#4930)) ##### Performance - Introduce winloop for windows as an alternative to uvloop ([#4996](psf/black#4996)) - Remove deprecated function `uvloop.install()` in favor of `uvloop.new_event_loop()` ([#4996](psf/black#4996)) - Rename `maybe_install_uvloop` function to `maybe_use_uvloop` to simplify loop installation and creation of either a uvloop/winloop evenloop or default eventloop ([#4996](psf/black#4996)) ##### Output - Emit a clear warning when the target Python version is newer than the running Python version, since AST safety checks cannot parse newer syntax. Also replace the misleading "INTERNAL ERROR" message with an actionable error explaining the version mismatch ([#4983](psf/black#4983)) ##### *Blackd* - Introduce winloop to be used when windows in use which enables blackd to run faster on windows when winloop is installed. ([#4996](psf/black#4996)) ##### Integrations - Remove unused gallery script ([#5030](psf/black#5030)) - Harden parsing of `black` requirements in the GitHub Action when `use_pyproject` is enabled so that only version specifiers are accepted and direct references such as `black @ https://...` are rejected. Users should upgrade to the latest version of the action as soon as possible. This update is received automatically when using `psf/black@stable`, and is independent of the version of Black installed by the action. ([#5031](psf/black#5031)) ##### Documentation - Expand preview style documentation with detailed examples for `wrap_comprehension_in`, `simplify_power_operator_hugging`, and `wrap_long_dict_values_in_parens` features ([#4987](psf/black#4987)) - Add detailed documentation for formatting Jupyter Notebooks ([#5009](psf/black#5009)) </details> --- ### Configuration 📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **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. --- - [ ] If you want to rebase/retry this PR, check this box --- This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).  Reviewed-on: https://git.tainton.uk/repos/epage/pulls/208 Reviewed-by: Luke Tainton <luke@tainton.uk> Co-authored-by: renovate[bot] <renovate-bot@git.tainton.uk> Co-committed-by: renovate[bot] <renovate-bot@git.tainton.uk>

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)) | `<26.1.1,>=26.1.0` → `<26.3.1,>=26.3.0` | ![age](https://developer.mend.io/api/mc/badges/age/pypi/black/26.3.0?slim=true) | ![confidence](https://developer.mend.io/api/mc/badges/confidence/pypi/black/26.1.0/26.3.0?slim=true) | --- ### Release Notes <details> <summary>psf/black (black)</summary> ### [`v26.3.0`](https://github.com/psf/black/blob/HEAD/CHANGES.md#2630) [Compare Source](psf/black@26.1.0...26.3.0) ##### Stable style - Don't double-decode input, causing non-UTF-8 files to be corrupted ([#4964](psf/black#4964)) - Fix crash on standalone comment in lambda default arguments ([#4993](psf/black#4993)) - Preserve parentheses when `# type: ignore` comments would be merged with other comments on the same line, preventing AST equivalence failures ([#4888](psf/black#4888)) ##### Preview style - Fix bug where `if` guards in `case` blocks were incorrectly split when the pattern had a trailing comma ([#4884](psf/black#4884)) - Fix `string_processing` crashing on unassigned long string literals with trailing commas (one-item tuples) ([#4929](psf/black#4929)) - Simplify implementation of the power operator "hugging" logic ([#4918](psf/black#4918)) ##### Packaging - Fix shutdown errors in PyInstaller builds on macOS by disabling multiprocessing in frozen environments ([#4930](psf/black#4930)) ##### Performance - Introduce winloop for windows as an alternative to uvloop ([#4996](psf/black#4996)) - Remove deprecated function `uvloop.install()` in favor of `uvloop.new_event_loop()` ([#4996](psf/black#4996)) - Rename `maybe_install_uvloop` function to `maybe_use_uvloop` to simplify loop installation and creation of either a uvloop/winloop evenloop or default eventloop ([#4996](psf/black#4996)) ##### Output - Emit a clear warning when the target Python version is newer than the running Python version, since AST safety checks cannot parse newer syntax. Also replace the misleading "INTERNAL ERROR" message with an actionable error explaining the version mismatch ([#4983](psf/black#4983)) ##### *Blackd* - Introduce winloop to be used when windows in use which enables blackd to run faster on windows when winloop is installed. ([#4996](psf/black#4996)) ##### Integrations - Remove unused gallery script ([#5030](psf/black#5030)) - Harden parsing of `black` requirements in the GitHub Action when `use_pyproject` is enabled so that only version specifiers are accepted and direct references such as `black @ https://...` are rejected. Users should upgrade to the latest version of the action as soon as possible. This update is received automatically when using `psf/black@stable`, and is independent of the version of Black installed by the action. ([#5031](psf/black#5031)) ##### Documentation - Expand preview style documentation with detailed examples for `wrap_comprehension_in`, `simplify_power_operator_hugging`, and `wrap_long_dict_values_in_parens` features ([#4987](psf/black#4987)) - Add detailed documentation for formatting Jupyter Notebooks ([#5009](psf/black#5009)) </details> --- ### Configuration 📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **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. --- - [ ] If you want to rebase/retry this PR, check this box --- This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).  Reviewed-on: https://git.tainton.uk/repos/PwnedPW/pulls/326 Reviewed-by: Luke Tainton <luke@tainton.uk> Co-authored-by: renovate[bot] <renovate-bot@git.tainton.uk> Co-committed-by: renovate[bot] <renovate-bot@git.tainton.uk>

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)) | `<26.1.1,>=26.1.0` → `<26.3.1,>=26.3.0` | ![age](https://developer.mend.io/api/mc/badges/age/pypi/black/26.3.0?slim=true) | ![confidence](https://developer.mend.io/api/mc/badges/confidence/pypi/black/26.1.0/26.3.0?slim=true) | --- ### Release Notes <details> <summary>psf/black (black)</summary> ### [`v26.3.0`](https://github.com/psf/black/blob/HEAD/CHANGES.md#2630) [Compare Source](psf/black@26.1.0...26.3.0) ##### Stable style - Don't double-decode input, causing non-UTF-8 files to be corrupted ([#4964](psf/black#4964)) - Fix crash on standalone comment in lambda default arguments ([#4993](psf/black#4993)) - Preserve parentheses when `# type: ignore` comments would be merged with other comments on the same line, preventing AST equivalence failures ([#4888](psf/black#4888)) ##### Preview style - Fix bug where `if` guards in `case` blocks were incorrectly split when the pattern had a trailing comma ([#4884](psf/black#4884)) - Fix `string_processing` crashing on unassigned long string literals with trailing commas (one-item tuples) ([#4929](psf/black#4929)) - Simplify implementation of the power operator "hugging" logic ([#4918](psf/black#4918)) ##### Packaging - Fix shutdown errors in PyInstaller builds on macOS by disabling multiprocessing in frozen environments ([#4930](psf/black#4930)) ##### Performance - Introduce winloop for windows as an alternative to uvloop ([#4996](psf/black#4996)) - Remove deprecated function `uvloop.install()` in favor of `uvloop.new_event_loop()` ([#4996](psf/black#4996)) - Rename `maybe_install_uvloop` function to `maybe_use_uvloop` to simplify loop installation and creation of either a uvloop/winloop evenloop or default eventloop ([#4996](psf/black#4996)) ##### Output - Emit a clear warning when the target Python version is newer than the running Python version, since AST safety checks cannot parse newer syntax. Also replace the misleading "INTERNAL ERROR" message with an actionable error explaining the version mismatch ([#4983](psf/black#4983)) ##### *Blackd* - Introduce winloop to be used when windows in use which enables blackd to run faster on windows when winloop is installed. ([#4996](psf/black#4996)) ##### Integrations - Remove unused gallery script ([#5030](psf/black#5030)) - Harden parsing of `black` requirements in the GitHub Action when `use_pyproject` is enabled so that only version specifiers are accepted and direct references such as `black @ https://...` are rejected. Users should upgrade to the latest version of the action as soon as possible. This update is received automatically when using `psf/black@stable`, and is independent of the version of Black installed by the action. ([#5031](psf/black#5031)) ##### Documentation - Expand preview style documentation with detailed examples for `wrap_comprehension_in`, `simplify_power_operator_hugging`, and `wrap_long_dict_values_in_parens` features ([#4987](psf/black#4987)) - Add detailed documentation for formatting Jupyter Notebooks ([#5009](psf/black#5009)) </details> --- ### Configuration 📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **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. --- - [ ] If you want to rebase/retry this PR, check this box --- This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).  Reviewed-on: https://git.tainton.uk/repos/roboluke/pulls/431 Co-authored-by: renovate[bot] <renovate-bot@git.tainton.uk> Co-committed-by: renovate[bot] <renovate-bot@git.tainton.uk>

Add unit test and changelog entry for lambda comment crash fix

2fdde64

Adds a test case for standalone comments in lambda default arguments that previously caused a LookupError crash (fixes psf#4640). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cobaltt7 mentioned this pull request Feb 21, 2026

Fix bug with standalone comments in lambda default arguments #4658

Closed

3 tasks

cobaltt7 added 2 commits March 1, 2026 13:04

Merge branch 'main' into fix-lambda-comment-crash

db24d77

Merge branch 'main' into fix-lambda-comment-crash

03b89de

cobaltt7 merged commit 88e7833 into psf:main Mar 2, 2026
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cobaltt7 added a commit that referenced this pull request Mar 2, 2026

Fix crash on standalone comment in lambda default arguments (#4993)

86a3bfb

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com> Co-authored-by: cobalt <61329810+cobaltt7@users.noreply.github.com>

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Fix crash on standalone comment in lambda default arguments#4993

Fix crash on standalone comment in lambda default arguments#4993
cobaltt7 merged 4 commits intopsf:mainfrom
worksbyfriday:fix-lambda-comment-crash

worksbyfriday commented Feb 17, 2026 •

edited by cobaltt7

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JelleZijlstra commented Feb 20, 2026

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worksbyfriday commented Feb 20, 2026

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worksbyfriday commented Feb 17, 2026 • edited by cobaltt7 Loading Uh oh! There was an error while loading. Please reload this page.

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JelleZijlstra commented Feb 20, 2026

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worksbyfriday commented Feb 20, 2026

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worksbyfriday commented Feb 17, 2026 •

edited by cobaltt7

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github-actions bot commented Feb 20, 2026 •

edited

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