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[pyupgrade] UP018 should detect more unnecessarily wrapped literals (UP018) - #24093

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MichaReiser merged 2 commits into
astral-sh:mainfrom
danparizher:fix-19864
Mar 30, 2026
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[pyupgrade] UP018 should detect more unnecessarily wrapped literals (UP018)#24093
MichaReiser merged 2 commits into
astral-sh:mainfrom
danparizher:fix-19864

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@danparizher danparizher commented Mar 21, 2026

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Summary

This PR extends UP018 (native-literals) to detect more unnecessarily wrapped literals

Closes #19864.

Problem

Currently, UP018 misses several cases of redundant literal constructors:

  1. int().denominator and similar attribute accesses on zero-value calls.
  2. Implicitly concatenated string/bytes literals.
  3. str() and complex() calls with redundant keyword arguments like object= or real=.
  4. complex() calls with complex literals.

Approach

  1. Added Complex to LiteralType enum and supported complex in LiteralType::from_str.
  2. Updated LiteralType::as_zero_value_expr to return 0j for Complex.
  3. Updated native_literals to:
    • Support redundant keyword arguments (object for str, real for complex).
    • Remove the check that skipped implicitly concatenated strings.
    • Wrap implicitly concatenated strings/bytes in parentheses if they span multiple lines to maintain valid syntax.
    • Wrap zero-value int in parentheses when followed by an attribute access (e.g., (0).denominator).

Test Plan

  • Added new test cases to crates/ruff_linter/resources/test/fixtures/pyupgrade/UP018.py.
  • Verified existing and new tests pass with cargo test -p ruff_linter pyupgrade::tests.
  • Manually verified with a reproduction script.
  • Verified with cargo clippy.

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astral-sh-bot Bot requested a review from ntBre March 21, 2026 04:27
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astral-sh-bot Bot commented Mar 21, 2026 •
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ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

MichaReiser
MichaReiser approved these changes Mar 30, 2026
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Comment thread crates/ruff_linter/src/rules/pyupgrade/rules/native_literals.rs
Comment thread crates/ruff_linter/resources/test/fixtures/pyupgrade/UP018.py
# t-strings are not native literals
str(t"hey")

# UP018 - Extended detections

@MichaReiser MichaReiser Mar 30, 2026

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Let's add a test for a single line implicit concatenated string or bytes literal that's followed by an attribute access

Comment thread crates/ruff_linter/resources/test/fixtures/pyupgrade/UP018.py
@MichaReiser

MichaReiser commented Mar 30, 2026

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Your PR summary suggests you might be using AI. If that's the case, please read our AI Policy (https://github.com/astral-sh/.github/blob/main/AI_POLICY.md)

@MichaReiser MichaReiser added the accepted Ready for implementation label Mar 30, 2026
@MichaReiser
MichaReiser merged commit ef5b550 into astral-sh:main Mar 30, 2026
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carljm added a commit that referenced this pull request Mar 31, 2026
@carljm
Merge branch 'main' into charlie/metaclass
20affc9 
* main: (35 commits)
  Store definition indexes as u32 (#24307)
  Avoid re-using symbol in RUF024 fix (#24316)
  [ty] Add materialization to `Divergent` type (#24255)
  [ty] Make `Divergent` a top-level type variant (#24252)
  [ty] Fix nested global and nonlocal lookups through forwarding scopes (#24279)
  Fetch the cargo-dist binary directly instead of using the installer (#24258)
  [ty] Fix panic on `list[Annotated[()]]` (#24303)
  Don't measure the AST deallocation time in parser benchmarks (#24301)
  Enable CodSpeed's memory benchmarks for simulation benchmarks (#24298)
  Upgrade imara-diff to 0.2.0 (#24299)
  [ty] Represent `InitVar` as a special form internally, not a class (#24248)
  `RUF067`: Allow dunder-named assignments in non-strict mode
  [`pyupgrade`] UP018 should detect more unnecessarily wrapped literals (UP018) (#24093)
  [ty] Remove unused `system.glob` method (#24300)
  [ty] Reject functional TypedDict with mismatched name (#24295)
  Update Rust crate arc-swap to v1.9.0 (#24292)
  [ty] Remove unused `@Todo(Functional TypedDicts)` (#24297)
  Update CodSpeedHQ/action action to v4.12.1 (#24290)
  Update taiki-e/install-action action to v2.69.6 (#24293)
  Update Rust crate toml to v1.0.7 (#24289)
  ...
@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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UP018 should detect more unnecessarily wrapped literals

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@danparizher @MichaReiser @ntBre