fix: fix rule behavior differences and refactor control flow analysis by fansenze · Pull Request #495 · web-infra-dev/rslint

fansenze · 2026-03-06T13:24:41Z

Summary

Fix rule behavior differences between rslint and ESLint/typescript-eslint, and refactor control flow analysis into a shared utility.

Rule Fixes

1. `no-invalid-void-type` — callable/construct signatures

void as return type in callable and construct signatures was incorrectly flagged. Added CallSignature and ConstructSignature to the valid context whitelist, matching typescript-eslint behavior.

2. `no-empty-function` — functions with comments

Functions containing only comments (e.g. function foo() { /* TODO */ }) were incorrectly reported as empty. Added comment detection to check for // and /* in function bodies.

3. `getter-return` — throw statements, control flow, and arrow expression bodies

Throw statements were not recognized as valid exit paths in getters.
finally { return; } overriding try block returns was not detected.
Arrow functions with expression bodies in property descriptors (e.g. get: () => value) were incorrectly flagged as missing a return. ESLint only checks getters with BlockStatement bodies.
Fixed rule.CreateRule() incorrectly prepending @typescript-eslint/ prefix to core ESLint rule names.

4. `array-callback-return` — mixed return-with-value and empty-return

When allowImplicit is false (default), callbacks mixing return value; and return; on different branches (e.g. if (a) return 1; else return;) were not flagged. Fixed allPathsReturn logic to require all return statements to have values when allowImplicit is disabled.

5. `no-unnecessary-boolean-literal-compare` — options parsing and type checking

Options from JSON config/test framework were silently ignored (type assertion failed for []interface{}/map[string]interface{}). Added JSON marshal/unmarshal fallback.
isNullableBoolean did not verify that a union type contains only boolean and nullable members, causing false positives for types like boolean | string | null. Fixed to reject unions with non-boolean/non-nullable members.

Control Flow Refactor

Replaced ~500 lines of hand-written control flow analysis across getter-return, array-callback-return, and constructor-super with a shared utility (internal/utils/flow.go) that leverages the binder's NodeFlagsHasImplicitReturn flag and ForEachReturnStatement.

AnalyzeFunctionReturns(node) — returns EndReachable, HasReturnWithValue, HasEmptyReturn
IsFunctionEndReachable(node) — checks if function end is reachable

This also fixes array-callback-return incorrectly treating try { return x; } catch(e) {} as valid (catch falls through without returning).

Checklist

Tests updated (or not required).
Documentation updated (or not required).

gemini-code-assist · 2026-03-06T13:25:05Z

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves three distinct behavioral inconsistencies between rslint and ESLint/typescript-eslint rules. The changes improve the accuracy and reliability of linting by refining how void types are handled in specific TypeScript signatures, ensuring functions with comments are correctly identified as non-empty, and significantly upgrading the control flow analysis for getter-return rules to account for various complex exit paths, including error throws. These adjustments aim to bring rslint's rule enforcement closer to established ESLint standards, enhancing its consistency and correctness.

Highlights

no-invalid-void-type rule: Corrected the rule to allow void as a return type in callable and construct signatures, aligning with typescript-eslint behavior.
no-empty-function rule: Updated the rule to no longer flag functions containing only comments as empty, matching typescript-eslint's approach.
getter-return rule: Enhanced control flow analysis to properly recognize throw statements, if/else, switch/case/default, and try/catch/finally blocks as valid exit paths in getters. Additionally, a fix was implemented for incorrect rule naming that caused the rule to be invisible via the IPC API.

Changelog

internal/plugins/typescript/rules/no_empty_function/no_empty_function.go
- Imported the strings package.
- Introduced a new helper function isBlockBodyEmpty to detect comments within function bodies.
- Modified the isBodyEmpty function to utilize isBlockBodyEmpty for various function types.
internal/plugins/typescript/rules/no_empty_function/no_empty_function_test.go
- Added new valid test cases for functions that contain only comments.
internal/plugins/typescript/rules/no_invalid_void_type/no_invalid_void_type.go
- Included ast.KindCallSignature and ast.KindConstructSignature in the whitelist for valid void return type contexts.
internal/plugins/typescript/rules/no_invalid_void_type/no_invalid_void_type_test.go
- Added new valid test cases for callable and construct signatures with void return types.
- Included an invalid test case for void used in a callable signature parameter position.
internal/rules/getter_return/getter_return.go
- Refactored the analyzeReturnPaths function to use a new pathResult enumeration for clearer control flow analysis.
- Implemented recursive analyzeStatements and analyzeStatement functions to handle return, throw, if/else, switch/case/default, and try/catch/finally statements.
- Added helper functions analyzeIfStatement, analyzeSwitchStatement, analyzeTryStatement, analyzeBranch, and combineResults for detailed control flow analysis.
- Adjusted the GetterReturnRule definition from rule.CreateRule(rule.Rule{...}) to a direct rule.Rule{...} to address a rule naming issue.
internal/rules/getter_return/getter_return_test.go
- Added numerous valid test cases for the getter-return rule, covering throw statements, try/catch blocks, and switch statements.
- Included new invalid test cases for if-throw without an else branch, switch statements without a default clause, and try/catch blocks where not all paths return.
packages/rslint-test-tools/rstest.config.mts
- Included getter-return.test.ts in the ESLint rules test configuration.
packages/rslint-test-tools/tests/eslint/rules/snapshots/getter-return.test.ts.snap
- Generated new snapshot tests for the getter-return rule's invalid cases.
packages/rslint-test-tools/tests/eslint/rules/getter-return.test.ts
- Added a new test file for the getter-return rule, including both valid and invalid test cases.
packages/rslint-test-tools/tests/typescript-eslint/rules/no-empty-function.test.ts
- Added new valid test cases for functions that contain comments.
packages/rslint-test-tools/tests/typescript-eslint/rules/no-invalid-void-type.test.ts
- Added new valid test cases for callable and construct signatures.

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Code Review

This pull request introduces several fixes to align rule behaviors with ESLint, which is a great improvement. The changes for no-invalid-void-type and no-empty-function seem correct and well-tested. The control flow analysis for getter-return is a significant and much-needed rewrite.

I've left a couple of suggestions for minor refactoring to improve maintainability and correctness by reducing code duplication and using more specific AST helper methods. Overall, this is a solid contribution.

internal/rules/getter_return/getter_return.go

- getter-return / array-callback-return / constructor-super: replace manual AST-based control flow analysis with shared utility using binder's NodeFlagsHasImplicitReturn, fixing try-catch false negatives - getter-return: skip arrow functions with expression bodies in property descriptors (e.g. `get: () => value`), matching ESLint's BlockStatement check - array-callback-return: fix false negative for mixed return-with-value and empty-return when allowImplicit is false (e.g. `if (a) return 1; else return;`) - no-unnecessary-boolean-literal-compare: fix options parsing from JSON config, fix isNullableBoolean to reject unions with non-boolean/non-nullable members - Add shared FunctionReturnAnalysis utility with tests - Update rule documentation with missing options - Enable no-unnecessary-boolean-literal-compare TS test suite

github-actions bot added the release: bug fix label Mar 6, 2026

gemini-code-assist bot reviewed Mar 6, 2026

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internal/rules/getter_return/getter_return.go Outdated Show resolved Hide resolved

fansenze force-pushed the fix/rule-behavior-fixes-20260306 branch 5 times, most recently from 1781e0b to 3b0a81c Compare March 9, 2026 06:20

fansenze changed the title ~~fix: fix 3 rule behavior differences with ESLint~~ fix: fix rule behavior differences with ESLint and refactor control flow analysis Mar 9, 2026

fansenze force-pushed the fix/rule-behavior-fixes-20260306 branch from 3b0a81c to cb3f5b4 Compare March 9, 2026 08:03

fansenze changed the title ~~fix: fix rule behavior differences with ESLint and refactor control flow analysis~~ fix: fix rule behavior differences and refactor control flow analysis Mar 9, 2026

fansenze force-pushed the fix/rule-behavior-fixes-20260306 branch from cb3f5b4 to 9ea1fca Compare March 9, 2026 08:34

fansenze force-pushed the fix/rule-behavior-fixes-20260306 branch from 9ea1fca to d507bc9 Compare March 9, 2026 08:45

fansenze requested a review from hardfist March 9, 2026 09:13

hardfist approved these changes Mar 9, 2026

View reviewed changes

fansenze merged commit 0ee755a into main Mar 9, 2026
14 checks passed

fansenze deleted the fix/rule-behavior-fixes-20260306 branch March 9, 2026 09:29

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fix: fix rule behavior differences and refactor control flow analysis#495

fix: fix rule behavior differences and refactor control flow analysis#495
fansenze merged 1 commit intomainfrom
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fansenze commented Mar 6, 2026 •

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fansenze commented Mar 6, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Summary

Rule Fixes

1. no-invalid-void-type — callable/construct signatures

2. no-empty-function — functions with comments

3. getter-return — throw statements, control flow, and arrow expression bodies

4. array-callback-return — mixed return-with-value and empty-return

5. no-unnecessary-boolean-literal-compare — options parsing and type checking

Control Flow Refactor

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fansenze commented Mar 6, 2026 •

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1. `no-invalid-void-type` — callable/construct signatures

2. `no-empty-function` — functions with comments

3. `getter-return` — throw statements, control flow, and arrow expression bodies

4. `array-callback-return` — mixed return-with-value and empty-return

5. `no-unnecessary-boolean-literal-compare` — options parsing and type checking