feat(ts): implement unnecessaryLogicalComparisons rule

[Copilot]

Implements lint rule to detect and simplify unnecessary boolean literal comparisons in TypeScript code.

Changes

• Rule implementation (packages/ts/src/rules/unnecessaryLogicalComparisons.ts)

  • Detects equality comparisons with boolean literals
  • Supports both strict (===, !==) and loose (==, !=) operators
  • Provides automatic fixes with proper negation handling
  • Unwraps parenthesized expressions in simplified output

• Test coverage (packages/ts/src/rules/unnecessaryLogicalComparisons.test.ts)

  • 33 test cases covering all operator and operand combinations
  • Edge cases: parenthesized expressions, member access, array indexing

• Registration

  • Added to plugin exports in alphabetical order
  • Marked as implemented in comparisons data

Examples

// ❌ Unnecessary comparisons
if (isActive === true) { }
const result = flag !== false;
while (condition == true) { }

// ✅ Simplified
if (isActive) { }
const result = flag;
while (condition) { }

// ❌ With negation
if (isActive === false) { }
const result = flag !== true;

// ✅ Simplified
if (!isActive) { }
const result = !flag;

Warning

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• typescript-eslint.io
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Original prompt

---

This section details on the original issue you should resolve

<issue_title>🚀 Feature: Implement unnecessaryLogicalComparisons rule (TypeScript)</issue_title>
<issue_description>### Feature Request Checklist

• I have pulled the latest main branch of the repository.
• I have searched for related issues and found none that matched my issue.

Overview

Per flint.fyi/rules, Flint is intended to have a unnecessaryLogicalComparisons rule in the TypeScript plugin (ts). It'll behave roughly equivalently to the existing implementations in other linters to start. This issue tracks adding that rule.

Adding this rule will entail creating the following new source files:

• packages/ts/src/rules/unnecessaryLogicalComparisons.ts: implementation of the rule itself
• packages/ts/src/rules/unnecessaryLogicalComparisons.test.ts: tests for the rule
• packages/site/src/content/docs/rules/ts/unnecessaryLogicalComparisons.mdx: documentation of the rule

Additionally, the following files will need to be edited:

• packages/comparisons/src/data.json: Comparisons data will need to mention the rule is now "status": "implemented"
• packages/ts/src/plugin.ts: Included rules should have the new one inserted in alphabetical order

Additional Info

Existing rules in other linters:

• Biome: useSimplifiedLogicExpression
• ESLint: @typescript-eslint/no-unnecessary-boolean-literal-compare
• Oxlint: typescript/no-unnecessary-boolean-literal-compare

❤️‍🔥</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes 🚀 Feature: Implement unnecessaryLogicalComparisons rule (TypeScript) #2230

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Project	Deployment	Actions	Updated (UTC)
flint	Ready	Preview, Comment	Feb 1, 2026 4:54pm

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⚠️ No Changeset found

Latest commit: dd8b41f

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[JoshuaKGoldberg]

The backing typescript-eslint rule is a good bit more complex. Marking as blocked until we have more built-up practices around Flint rules.