jsx-eslint/eslint-plugin-react

react/no-unused-prop-types false positive when using memo

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#3,403 opened on Sep 5, 2022

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bughelp wanted

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Description

Here's an example using CRA

Expected: No warning

Actual:

  • npm run lint
eslint-example/src/App.js
  23:3  warning  'showFirst' PropType is defined but prop is never used  react/no-unused-prop-types

This started when going from version 7.30.0 to 7.30.1.

  • If I remove memo the warning goes away
  • If I wrap the ternary in the return with a fragment the warning goes away but then I'd have to silence react/jsx-no-useless-fragment so not helpful either.

Contributor guide

Research direction
Inspect the rule `react/no unused prop types` in the plugin source code. Look for changes between v7.30.0 and v7.30.1 that might have introduced the false positive when `React.memo` wraps the component. Check how the rule detects prop usage and why `memo` causes it to miss the ternary expression.
Tech stack
javascriptreact
Domain
frontend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
JavaScriptESLintReact
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40