react / react/react

Bug: react-hooks/exhaustive-deps false positive when use function with generic type variable in useEffect

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#25,149 4 comments 1 reaction 0 assignees View on GitHub

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Component: ESLint Rules Status: Unconfirmed Type: Bug
Dominant language
JavaScript
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Description

React version: 18.2.0

Steps To Reproduce

  1. use function with generic type in useEffect

code example:

function useBug<T>(val: T) {
  const ref = useRef<T>(val)

  const fn = () => {
    const temp: T = ref.current // <-- if remove the generic type will be ok
  }

  useEffect(() => {
    fn()
  }, []) // <-- ESLint error: React Hook useEffect has a missing dependency: 'fn'.
}

package version:

npmPackages:
    @typescript-eslint/eslint-plugin: ^5.35.1 => 5.35.1 
    @typescript-eslint/parser: ^5.35.1 => 5.35.1 
    @typescript-eslint/scope-manager:  5.35.1 
    @typescript-eslint/type-utils:  5.35.1 
    @typescript-eslint/types:  5.35.1 
    @typescript-eslint/typescript-estree:  5.35.1 
    @typescript-eslint/utils:  5.35.1 
    @typescript-eslint/visitor-keys:  5.35.1 
    eslint: ^8.23.0 => 8.23.0 
    eslint-plugin-react-hooks: ^4.6.0 => 4.6.0 

relevant: #20395

The current behavior

React Hook useEffect has a missing dependency: 'fn'. Either include it or remove the dependency array.

The expected behavior

No missing dependencies reported.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the minimal TypeScript reproduction in the issue and inspect the eslint-plugin-react-hooks exhaustive-deps implementation. Verify the generic useEffect example, then add or update coverage so this case no longer reports a missing fn dependency while existing dependency warnings remain intact.

Written by the indexing model from the issue text.

Assessment

Tech stack
eslint, javascript, react, typescript
Domain
frontend, tooling
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Clearly specified
Newbie friendliness
35/100

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