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[useEvent] Lint for presence of useEvent functions in dependency lists (
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#25512)

* [useEvent] Lint for presence of useEvent functions in dependency lists

With #25473, the identity of useEvent's return value is no longer stable
across renders. Previously, the ExhaustiveDeps lint rule would only
allow the omission of the useEvent function, but you could still add it
as a dependency.

This PR updates the ExhaustiveDeps rule to explicitly check for the
presence of useEvent functions in dependency lists, and emits a warning
and suggestion/autofixer for removing the dependency.
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poteto authored Oct 19, 2022
1 parent 3cc792b commit 9336e29
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Showing 2 changed files with 74 additions and 10 deletions.
Original file line number Diff line number Diff line change
Expand Up @@ -7635,15 +7635,53 @@ if (__EXPERIMENTAL__) {
...tests.valid,
{
code: normalizeIndent`
function MyComponent({ theme }) {
const onStuff = useEvent(() => {
showNotification(theme);
});
useEffect(() => {
onStuff();
}, []);
}
`,
function MyComponent({ theme }) {
const onStuff = useEvent(() => {
showNotification(theme);
});
useEffect(() => {
onStuff();
}, []);
}
`,
},
];

tests.invalid = [
...tests.invalid,
{
code: normalizeIndent`
function MyComponent({ theme }) {
const onStuff = useEvent(() => {
showNotification(theme);
});
useEffect(() => {
onStuff();
}, [onStuff]);
}
`,
errors: [
{
message:
'Functions returned from `useEvent` must not be included in the dependency array. ' +
'Remove `onStuff` from the list.',
suggestions: [
{
desc: 'Remove the dependency `onStuff`',
output: normalizeIndent`
function MyComponent({ theme }) {
const onStuff = useEvent(() => {
showNotification(theme);
});
useEffect(() => {
onStuff();
}, []);
}
`,
},
],
},
],
},
];
}
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28 changes: 27 additions & 1 deletion packages/eslint-plugin-react-hooks/src/ExhaustiveDeps.js
Original file line number Diff line number Diff line change
Expand Up @@ -74,6 +74,7 @@ export default {
const stateVariables = new WeakSet();
const stableKnownValueCache = new WeakMap();
const functionWithoutCapturedValueCache = new WeakMap();
const useEventVariables = new WeakSet();
function memoizeWithWeakMap(fn, map) {
return function(arg) {
if (map.has(arg)) {
Expand Down Expand Up @@ -226,7 +227,12 @@ export default {
// useRef() return value is stable.
return true;
} else if (isUseEventIdentifier(callee) && id.type === 'Identifier') {
// useEvent() return value is stable.
for (const ref of resolved.references) {
if (ref !== id) {
useEventVariables.add(ref.identifier);
}
}
// useEvent() return value is always unstable.
return true;
} else if (name === 'useState' || name === 'useReducer') {
// Only consider second value in initializing tuple stable.
Expand Down Expand Up @@ -639,6 +645,26 @@ export default {
});
return;
}
if (useEventVariables.has(declaredDependencyNode)) {
reportProblem({
node: declaredDependencyNode,
message:
'Functions returned from `useEvent` must not be included in the dependency array. ' +
`Remove \`${context.getSource(
declaredDependencyNode,
)}\` from the list.`,
suggest: [
{
desc: `Remove the dependency \`${context.getSource(
declaredDependencyNode,
)}\``,
fix(fixer) {
return fixer.removeRange(declaredDependencyNode.range);
},
},
],
});
}
// Try to normalize the declared dependency. If we can't then an error
// will be thrown. We will catch that error and report an error.
let declaredDependency;
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