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[pyflakes] Flag annotated variable redeclarations as F811 in preview mode - #24244

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dylwil3 merged 6 commits into
astral-sh:mainfrom
ai-mountain:fix/f811-annotated-assignment-redefinition-preview
Mar 27, 2026
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[pyflakes] Flag annotated variable redeclarations as F811 in preview mode#24244
dylwil3 merged 6 commits into
astral-sh:mainfrom
ai-mountain:fix/f811-annotated-assignment-redefinition-preview

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@ai-mountain

@ai-mountain ai-mountain commented Mar 27, 2026

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Summary

  • In preview mode, F811 now detects annotated variable redeclarations like bar: int = 1; bar: int = 2 as unused redefinitions
  • Plain reassignments (x = 1; x = 2) remain unflagged, as this is normal Python
  • Only triggers when both the original and the shadowing binding are annotated assignments with values
    • bar: int = 1; bar: int = 2 — flagged
    • bar = 1; bar = 2 — not flagged (plain reassignment)
    • bar = 1; bar: int = 2 — not flagged (mixed)
    • bar: int = 1; bar = 2 — not flagged (mixed)
    • bar: int = 1; print(bar); bar: int = 2 — not flagged (first is used)

Closes #23802

Test plan

  • Added F811_34.py test fixture covering all combinations (annotated/plain, used/unused)
  • All 35 existing F811 tests pass with no regressions
  • Full pyflakes suite passes (463 tests)

@astral-sh-bot
astral-sh-bot Bot requested a review from amyreese March 27, 2026 14:56
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astral-sh-bot Bot commented Mar 27, 2026 •
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ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

ℹ️ ecosystem check detected linter changes. (+1 -0 violations, +0 -0 fixes in 1 projects; 55 projects unchanged)

prefecthq/prefect (+1 -0 violations, +0 -0 fixes) 

ruff check --no-cache --exit-zero --no-fix --output-format concise --preview

+ src/prefect/client/schemas/responses.py:366:5: F811 Redefinition of unused `concurrency_options` from line 359: `concurrency_options` redefined here

Changes by rule (1 rules affected)

code total + violation - violation + fix - fix
F811 1 1 0 0 0

@MichaReiser MichaReiser assigned dylwil3 and unassigned amyreese Mar 27, 2026
@dylwil3

dylwil3 commented Mar 27, 2026

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Thanks for your interest in contributing to Ruff! Could you please take a look at the AI policy and make any necessary adjustments?

@MichaReiser
MichaReiser requested review from dylwil3 and removed request for amyreese March 27, 2026 16:24
@ai-mountain

ai-mountain commented Mar 27, 2026

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@dylwil3 I checked every line one by one and all are good implemented. I used a BindingFlags flag instead of checking the statement directly. The preview gate is in the F811 checker rather than in redefines() because the semantic crate doesn't have access to linter settings. I updated the function in mod.rs. I think my PR is good but I expect any review from you.

@dylwil3
dylwil3 force-pushed the fix/f811-annotated-assignment-redefinition-preview branch from 3c9dcc1 to cc4f43c Compare March 27, 2026 17:58
@dylwil3

dylwil3 commented Mar 27, 2026

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Ok, thank you! I think we can get away with something a bit simpler without introducing a new flag. I pushed a different approach, we'll see if CI passes but it ought to be equivalent.

@dylwil3 dylwil3 added rule Implementing or modifying a lint rule preview Related to preview mode features labels Mar 27, 2026
@dylwil3 dylwil3 changed the title Flag annotated variable redeclarations as F811 in preview mode [pyflakes] Flag annotated variable redeclarations as F811 in preview mode Mar 27, 2026
dylwil3
dylwil3 reviewed Mar 27, 2026
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Comment thread crates/ruff_linter/src/rules/pyflakes/rules/redefined_while_unused.rs
dylwil3
dylwil3 requested changes Mar 27, 2026
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Thanks! Just need some documentation.

@ai-mountain
ai-mountain requested a review from dylwil3 March 27, 2026 18:41
@dylwil3
dylwil3 merged commit f283ddc into astral-sh:main Mar 27, 2026
42 checks passed
carljm added a commit that referenced this pull request Mar 31, 2026
@carljm
Merge branch 'main' into charlie/metaclass
3bd98a5 
* main: (40 commits)
  [ty] resolve union-likes in emitting union attribute errors (#24263)
  [ty] Improve support for `Callable` type context (#23888)
  [ty] Propagate type context through `await` expressions (#24256)
  [`pyflakes`] Flag annotated variable redeclarations as `F811` in preview mode (#24244)
  [ty] Preserve `Divergent` when materializing recursive aliases (#24245)
  Fix W391 fixes for consecutive empty notebook cells (#24236)
  [flake8-bugbear] Clarify RUF071 fix safety for non-path string comparisons (#24149)
  [ty] Ban type qualifiers in PEP-695 type aliases (#24242)
  [ty] Include keyword-prefixed symbols in completions for attributes (#24232)
  [ty] Add tests for TypedDict method overloads on unions (#24230)
  [ty] report unused bindings as unnecessary hint diagnostics (#23305)
  Remove unused `non_root` variable (#24238)
  Extend F507 to flag %-format strings with zero placeholders (#24215)
  [`flake8-simplify`] Suppress `SIM105` for `except*` before Python 3.12 (#23869)
  Ignore pre-initialization references in SIM113 (#24235)
  Parenthesize expression in RUF050 fix (#24234)
  Publish playgrounds using the `release-playground` environment (#24223)
  [ty] Fix instance-attribute lookup in methods of protocol classes (#24213)
  [ty] Used shared expression cache during generic call inference (#24219)
  [ty] make `Type::BoundMethod` include instances of same-named methods bound to a subclass (#24039)
  ...
@BrewTestBot BrewTestBot mentioned this pull request Apr 2, 2026
Merged
nicopauss pushed a commit to Intersec/lib-common that referenced this pull request Jun 4, 2026
@renovate-bot @nicopauss
chore(deps): update dependency ruff to v0.15.10 (2024.6)
a1a28be 
##### [\`v0.15.10\`](https://github.com/astral-sh/ruff/blob/HEAD/CHANGELOG.md#01510)

Released on 2026-04-09.

##### Preview features

- \[`flake8-logging`] Allow closures in except handlers (`LOG004`) ([#24464](astral-sh/ruff#24464))
- \[`flake8-self`] Make `SLF` diagnostics robust to non-self-named variables ([#24281](astral-sh/ruff#24281))
- \[`flake8-simplify`] Make the fix for `collapsible-if` safe in `preview` (`SIM102`) ([#24371](astral-sh/ruff#24371))

##### Bug fixes

- Avoid emitting multi-line f-string elements before Python 3.12 ([#24377](astral-sh/ruff#24377))
- Avoid syntax error from `E502` fixes in f-strings and t-strings ([#24410](astral-sh/ruff#24410))
- Strip form feeds from indent passed to `dedent_to` ([#24381](astral-sh/ruff#24381))
- \[`pyupgrade`] Fix panic caused by handling of octals (`UP012`) ([#24390](astral-sh/ruff#24390))
- Reject multi-line f-string elements before Python 3.12 ([#24355](astral-sh/ruff#24355))

##### Rule changes

- \[`ruff`] Treat f-string interpolation as potential side effect (`RUF019`) ([#24426](astral-sh/ruff#24426))

##### Server

- Add support for custom file extensions ([#24463](astral-sh/ruff#24463))

##### Documentation

- Document adding fixes in CONTRIBUTING.md ([#24393](astral-sh/ruff#24393))
- Fix JSON typo in settings example ([#24517](astral-sh/ruff#24517))

##### Contributors

- [@charliermarsh](https://github.com/charliermarsh)
- [@dylwil3](https://github.com/dylwil3)
- [@silverstein](https://github.com/silverstein)
- [@anishgirianish](https://github.com/anishgirianish)
- [@shizukushq](https://github.com/shizukushq)
- [@zanieb](https://github.com/zanieb)
- [@AlexWaygood](https://github.com/AlexWaygood)
##### [\`v0.15.9\`](https://github.com/astral-sh/ruff/blob/HEAD/CHANGELOG.md#0159)

Released on 2026-04-02.

##### Preview features

- \[`pyflakes`] Flag annotated variable redeclarations as `F811` in preview mode ([#24244](astral-sh/ruff#24244))
- \[`ruff`] Allow dunder-named assignments in non-strict mode for `RUF067` ([#24089](astral-sh/ruff#24089))

##### Bug fixes

- \[`flake8-errmsg`] Avoid shadowing existing `msg` in fix for `EM101` ([#24363](astral-sh/ruff#24363))
- \[`flake8-simplify`] Ignore pre-initialization references in `SIM113` ([#24235](astral-sh/ruff#24235))
- \[`pycodestyle`] Fix `W391` fixes for consecutive empty notebook cells ([#24236](astral-sh/ruff#24236))
- \[`pyupgrade`] Fix `UP008` nested class matching ([#24273](astral-sh/ruff#24273))
- \[`pyupgrade`] Ignore strings with string-only escapes (`UP012`) ([#16058](astral-sh/ruff#16058))
- \[`ruff`] `RUF072`: skip formfeeds on dedent ([#24308](astral-sh/ruff#24308))
- \[`ruff`] Avoid re-using symbol in `RUF024` fix ([#24316](astral-sh/ruff#24316))
- \[`ruff`] Parenthesize expression in `RUF050` fix ([#24234](astral-sh/ruff#24234))
- Disallow starred expressions as values of starred expressions ([#24280](astral-sh/ruff#24280))

##### Rule changes

- \[`flake8-simplify`] Suppress `SIM105` for `except*` before Python 3.12 ([#23869](astral-sh/ruff#23869))
- \[`pyflakes`] Extend `F507` to flag `%`-format strings with zero placeholders ([#24215](astral-sh/ruff#24215))
- \[`pyupgrade`] `UP018` should detect more unnecessarily wrapped literals (UP018) ([#24093](astral-sh/ruff#24093))
- \[`pyupgrade`] Fix `UP008` callable scope handling to support lambdas ([#24274](astral-sh/ruff#24274))
- \[`ruff`] `RUF010`: Mark fix as unsafe when it deletes a comment ([#24270](astral-sh/ruff#24270))

##### Formatter

- Add `nested-string-quote-style` formatting option ([#24312](astral-sh/ruff#24312))

##### Documentation

- \[`flake8-bugbear`] Clarify RUF071 fix safety for non-path string comparisons ([#24149](astral-sh/ruff#24149))
- \[`flake8-type-checking`] Clarify import cycle wording for `TC001`/`TC002`/`TC003` ([#24322](astral-sh/ruff#24322))

##### Other changes

- Avoid rendering fix lines with trailing whitespace after `|` ([#24343](astral-sh/ruff#24343))

##### Contributors

- [@charliermarsh](https://github.com/charliermarsh)
- [@MichaReiser](https://github.com/MichaReiser)
- [@tranhoangtu-it](https://github.com/tranhoangtu-it)
- [@dylwil3](https://github.com/dylwil3)
- [@zsol](https://github.com/zsol)
- [@renovate](https://github.com/renovate)
- [@bitloi](https://github.com/bitloi)
- [@danparizher](https://github.com/danparizher)
- [@chinar-amrutkar](https://github.com/chinar-amrutkar)
- [@second-ed](https://github.com/second-ed)
- [@getehen](https://github.com/getehen)
- [@Redovo1](https://github.com/Redovo1)
- [@matthewlloyd](https://github.com/matthewlloyd)
- [@zanieb](https://github.com/zanieb)
- [@InSyncWithFoo](https://github.com/InSyncWithFoo)
- [@RenzoMXD](https://github.com/RenzoMXD)

Renovate-Branch: renovate/2024.6-ruff-0.15.x
Change-Id: Id4bd542d4f128b509284d9dcda312f2b39c29964
Priv-Id: 28ebcacdeffa50cec7a52eee59091a75ca5e9539
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redefined-while-unused (F811) - false negative on variable redeclaration

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@ai-mountain @dylwil3 @amyreese