Microsoft/TypeScript

Flag boolean in comparison operator operands as errors

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#15,506 opened on May 1, 2017

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 (13 comments) (0 reactions) (0 assignees)TypeScript (48,455 stars) (6,726 forks)batch import
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Description

From https://github.com/Microsoft/TypeScript/issues/15444#issuecomment-298055832

var x: boolean, y: boolean;
if (x > y) {  // suspicious!
}

Contributor guide

Tech stack
typescript
Domain
tooling
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
TypeScript basicsUnderstanding of ASTFamiliarity with type checking
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
Investigate the TypeScript compiler's checker logic in src/compiler/checker.ts to find where comparisons are validated. The issue references #15444 for more context. Look for existing checks for other comparison types and extend to flag boolean comparisons. Consider how to handle the suggested warning and whether it should be a compile error or a lint style warning.