fix(prefer-optional-chain): avoid false positives for instanceof and redundant nullish checks#753
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camc314 merged 2 commits intooxc-project:mainfrom Mar 17, 2026
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@wagenet mind rebasing? thanks |
Contributor
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May want to double check main has these fixed, looks pretty similar to my other PR that was merged. AI wanted to add instanceof also but those weren't actually being triggered at least the ones I tried |
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in/instanceof and redundant nullish checks…f` and redundant nullish checks Two false positives are fixed: 1. `in`/`instanceof` operators: expressions like `(!a.b || key in a.b)` or `(a.b && foo instanceof a.b)` were incorrectly flagged because `in` and `instanceof` have no optional-chain equivalent. Add `KindInKeyword` and `KindInstanceOfKeyword` to the invalid-operator switches in both the AND-chain and OR-chain branches of `parseOperand`. 2. Redundant nullish checks: `a.b === null || a.b === undefined` was falsely reported because the chain passed `hasPropertyAccessInChain` (a.b is an access expression) even though both operands check the exact same expression with no deeper member access to convert. Add an `allOperandsCheckSameExpression` guard to `validateOrChainForReporting`, mirroring the identical guard already present in `validateAndChainForReporting`. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Summary
instanceoffalse positive: patterns like(!a.b || foo instanceof a.b)and(a.b && foo instanceof a.b)were incorrectly flagged. AddedKindInstanceOfKeywordto the invalid-operator switches in both the AND-chain and OR-chain branches ofparseOperand—instanceofhas no optional-chain equivalent.Redundant nullish-check false positive:
a.b === null || a.b === undefinedwas falsely reported because both operands check the exact same expression with no deeper member access to convert. Added anallOperandsCheckSameExpressionguard tovalidateOrChainForReporting, mirroring the identical guard already present invalidateAndChainForReporting.Test plan
(!a.b || foo instanceof a.b)— no violation(a.b && foo instanceof a.b)— no violationrequest.payload === null || request.payload === undefined— no violationrequest.payload === undefined || request.payload === null— no violationgo test ./internal/rules/prefer_optional_chain/...passes🤖 Generated with Claude Code