[react-hooks/exhaustive-deps] missed warning when passing a function

[whatisaphone]

Do you want to request a feature or report a bug?

Arguably a bug in eslint-plugin-react-hooks

What is the current behavior?

The exhaustive-deps rule does not catch the following case:

const FooContext = React.createContext(() => {});

// Meanwhile, somewhere deep in the component tree
function Bar() {
  const foo = useContext(FooContext);
  useEffect(foo, []);
  return <div>A div walks into a Bar…</div>;
}

What is the expected behavior?

I think the plugin should suggest adding the dependency on foo:

useEffect(foo, [foo]);

It already makes this suggestion for the verbose form of the code:

// This code:
useEffect(() => foo(), []);
// is fixed to:
useEffect(() => foo(), [foo]);

Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?

• eslint@6.2.2
• eslint-plugin-react-hooks@2.0.1
• react@16.9.0

[threepointone]

It's a bit of a niche usecase where a function is used directly as useEffect's callback (consider in your example, that the callback would have no access to state or any local variables.) That said, I can see how it would be useful when the need does arise. I think we'd accept a PR for this.

[simbathesailor]

@threepointone : Hey I have made good progress in this. Can I take up this issue?.. I have done the fix , but now I have to give it polishes with test cases. I will keep it posted here !!. I will try to make it according to existing code standard by this weekend. And we will take it from there !!.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contribution.

[gaearon]

The fact that it doesn't suggest it is a bug.