[ruff] Implement unnecessary-nested-literal (RUF039)
#14323
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| code | total | + violation | - violation | + fix | - fix |
|---|---|---|---|---|---|
| RUF039 | 2 | 2 | 0 | 0 | 0 |
MichaReiser
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@AlexWaygood would you mind doing a quick glance at the rule definition? I already reviewed the code
crates/ruff_linter/src/rules/ruff/rules/unnecessary_nested_literal.rs
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| if !is_nested { | ||
| return; | ||
| } |
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Can you expand on why we have to check inside the rule whether it is a nested literal, considering that the rule is only called when semantic.in_nested_literal is true?
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We only consider the top-level union, so when semantic.in_nested_literal is false. I've considered to run this run only when semantic.in_nested_literal is true, but then the top-level union is unavailable for the autofix.
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Oh, we actually only run the rule when not in a nested literal...
crates/ruff_linter/src/rules/ruff/rules/unnecessary_nested_literal.rs
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…eral.rs Co-authored-by: Micha Reiser <[email protected]>
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| /// RUF039 | ||
| pub(crate) fn unnecessary_nested_literal<'a>(checker: &mut Checker, literal_expr: &'a Expr) { | ||
| let mut nodes: Vec<&Expr> = Vec::new(); |
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It might also be worth to use a SmallVec here with a size of 1 to avoid allocating if this is a not-nested literal.
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nodes will be populated with all entries in Literal, so even for not-nested literals it can exceed 1. Shall I do a first pass to check if the Literal is nested, followed by another to collect the nodes? This will reduce the allocation on the common path.
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I think checking first and then collecting could be good for performance
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Similar to #14319 (review), I feel like I'm not sure how much this antipattern really comes up in practice. But, I can see the value if this is a pattern that could be introduced by the fix for other rules we implement!
crates/ruff_linter/src/rules/ruff/rules/unnecessary_nested_literal.rs
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…eral.rs Co-authored-by: Alex Waygood <[email protected]>
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Is there any open feedback that needs addressing? I'm otherwise happy to merge this rule. |
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My feedback has been addressed, but it looks like there's quite a few merge conflicts here. The conversations in #14323 (comment) and #14323 (comment) are also not marked as "resolved", and I think you're better placed to judge whether they should be or not ;) |
Summary
Implementing
unnecessary-nested-literal.This rule could help simplify other rules' fixes by handling the flattening of
Literals here.See also https://github.com/astral-sh/ruff/pull/14270/files#r1837810594 (unions in a follow-up PR)
Test Plan
cargo testThe ecosystem results are correct.
Some of the nesting emits multiple violations.
I've got a fix for this, but that depends on #14280.
We can go on with merging this PR after review regardless (the violations are not wrong).