[flake8-simplify] Fix SIM222 false positive for tuple(generator) or None (SIM222)
#21187
+32
−2
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Contributor
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ntBre
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ntBre
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Nov 3, 2025
| // is falsy. | ||
| if matches!( | ||
| &arguments.args[0], | ||
| Expr::Generator(_) | Expr::ListComp(_) | Expr::SetComp(_) |
Contributor
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I think this only needs to include Generator, not the comprehension types. Recursing into the Self::from_expr arm below should already return Self::Unknown for other comprehensions. Generators are the only special case on 1223, if I'm following correctly.
The last two new tests already suppress the rule, for example: https://play.ruff.rs/a211c51a-b6f3-4dae-b259-431a75788464
MichaReiser
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Nov 10, 2025
dcreager
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Nov 11, 2025
* origin/main: (38 commits) [ty] Make implicit submodule imports only occur in global scope (#21370) [ty] introduce local variables for `from` imports of submodules in `__init__.py(i)` (#21173) [`ruff`] Ignore `str()` when not used for simple conversion (`RUF065`) (#21330) [ty] implement `typing.NewType` by adding `Type::NewTypeInstance` [ty] supress inlay hints for `+1` and `-1` (#21368) [ty] Use type context for inference of generic constructors (#20933) [ty] Improve generic call expression inference (#21210) [ty] supress some trivial expr inlay hints (#21367) [`configuration`] Fix unclear error messages for line-length values exceeding `u16::MAX` (#21329) [ty] Fix incorrect inference of `enum.auto()` for enums with non-`int` mixins, and imprecise inference of `enum.auto()` for single-member enums (#20541) [`refurb`] Detect empty f-strings (`FURB105`) (#21348) [ty] provide `import` completion when in `from <name> <name>` statement (#21291) [ty] elide redundant inlay hints for function args (#21365) Fix syntax error false positive on alternative `match` patterns (#21362) Add a new "Opening a PR" section to the contribution guide (#21298) [`flake8-simplify`] Fix SIM222 false positive for `tuple(generator) or None` (`SIM222`) (#21187) Rebuild ruff binary instead of sharing it across jobs (#21361) [ty] Fix `--exclude` and `src.exclude` merging (#21341) [ty] Add support for properties that return `Self` (#21335) Add upstream linter URL to `ruff linter --output-format=json` (#21316) ...
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Summary
Fixes #21136. The rule was incorrectly treating
tuple(generator)as always truthy, buttuple(empty_generator)is falsy.Problem Analysis
SIM222 was incorrectly suggesting to remove
or Nonefromtuple(item for item in items) or Nonebecause it was treating the tuple call as always truthy. However, when a generator expression is empty,tuple(empty_generator)produces an empty tuple(), which is falsy. Removingor Nonewould change the runtime behavior.Approach
Updated
Truthiness::from_exprto returnUnknownfortuple(generator),tuple(list_comp), andtuple(set_comp)calls, since we cannot statically determine if the resulting tuple will be empty or not. This prevents SIM222 from flagging these cases incorrectly.