fix: align prefer-const with ESLint implementation#621
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This pull request enhances the prefer-const rule by implementing auto-fix capabilities for variable declaration lists and improving the handling of destructuring assignments to align with ESLint semantics. It introduces several utility functions for scope resolution and destructuring traversal. Feedback focuses on optimizing performance by caching block-level variable lookups and ensuring correct symbol resolution in the write-counting logic to properly handle variable shadowing.
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Fix 8 bugs in the prefer-const rule to fully align detection, reporting location, and auto-fix behavior with ESLint's implementation. Bug fixes: - Fix cross-declaration destructuring in same scope not being reported - Fix `hasTargetNotInSet` missing leaf Identifier nodes in PropertyAssignment - Fix `destructuring: "all"` not checking write-level destructuring grouping - Fix `findEnclosingScope` missing ClassStaticBlockDeclaration - Fix `hasTargetNotInSet` missing SpreadAssignment in object destructuring - Fix shorthand name-based matching false-matching shadowed variables - Fix `countWritesByName` lacking scope awareness for shadowed variables - Fix reporting vs fix suppression for same-scope var/const in destructuring Auto-fix: - Implement `let` → `const` auto-fix when all bindings in VDL are const-eligible - Correctly suppress fix when not all bindings can be const or declarations are uninitialized Public utilities extracted: - `utils.FindEnclosingScope` — reusable scope boundary finder (also adopted by no-var) - `utils.VisitDestructuringIdentifiers` — reusable destructuring assignment pattern walker Refactored to use existing public functions: - Replace custom `collectBindingNames` with `utils.CollectBindingNames` - Replace hardcoded scope boundary list with `ast.IsFunctionLikeOrClassStaticBlockDeclaration` Test coverage: 192 test cases across 8 dimensions (vs ESLint's 125).
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simplyme0823
approved these changes
Apr 9, 2026
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Summary
prefer-construle to fully align detection, reporting location, and auto-fix behavior with ESLint's implementation.let→constauto-fix when all bindings in the VariableDeclarationList are const-eligible.FindEnclosingScopeandVisitDestructuringIdentifiersas public utilities ininternal/utils/for reuse by other rules (e.g.,no-var).utils.CollectBindingNames,ast.IsFunctionLikeOrClassStaticBlockDeclaration.Bug fixes
hasUnmergeableTargetchecked same VDL instead of same block scopehasTargetNotInSetmissed leaf Identifier nodes in PropertyAssignment valuesdestructuring: "all"didn't check write-level destructuring groupingfindEnclosingScopemissingClassStaticBlockDeclarationhasTargetNotInSetmissingSpreadAssignmentin object destructuringcountWritesByNamelacked scope awareness for shadowed variablescollectBlockAllVarNamesmissed imports/params/function declarations — used name-set instead of symbol-based scope checkingCode quality improvements
countWritesByName→countWritesBySym: accept symbol from caller instead of fragile re-resolutionhasNonReportableDestructuringTarget: replaced name-set approach with TypeChecker symbol-based scope comparison to handle all declaration types (imports, parameters, function/class declarations)isReadBeforeFirstAssigncall inshouldReportcollectBlockAllVarNamesfunctionVerification
--fixoutput byte-identical to ESLint on same inputRelated Links
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