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Warn if number of hooks increases #14591

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merged 1 commit into from
Jan 17, 2019
Merged

Warn if number of hooks increases #14591

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32 changes: 18 additions & 14 deletions packages/react-reconciler/src/ReactFiberHooks.js
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,8 @@ import {
} from './ReactFiberScheduler';

import invariant from 'shared/invariant';
import warning from 'shared/warning';
import getComponentName from 'shared/getComponentName';
import areHookInputsEqual from 'shared/areHookInputsEqual';
import {markWorkInProgressReceivedUpdate} from './ReactFiberBeginWork';

Expand Down Expand Up @@ -104,8 +106,6 @@ let componentUpdateQueue: FunctionComponentUpdateQueue | null = null;
// map of queue -> render-phase updates, which are discarded once the component
// completes without re-rendering.

// Whether the work-in-progress hook is a re-rendered hook
let isReRender: boolean = false;
// Whether an update was scheduled during the currently executing render pass.
let didScheduleRenderPhaseUpdate: boolean = false;
// Lazily created map of render-phase updates
Expand Down Expand Up @@ -147,7 +147,6 @@ export function renderWithHooks(
// remainingExpirationTime = NoWork;
// componentUpdateQueue = null;

// isReRender = false;
// didScheduleRenderPhaseUpdate = false;
// renderPhaseUpdates = null;
// numberOfReRenders = -1;
Expand All @@ -163,6 +162,21 @@ export function renderWithHooks(
componentUpdateQueue = null;

children = Component(props, refOrContext);

if (__DEV__) {
if (
current !== null &&
workInProgressHook !== null &&
currentHook === null
) {
warning(
false,
'%s: Rendered more hooks than during the previous render. This is ' +
'not currently supported and may lead to unexpected behavior.',
getComponentName(Component),
);
}
}
} while (didScheduleRenderPhaseUpdate);

renderPhaseUpdates = null;
Expand All @@ -188,9 +202,6 @@ export function renderWithHooks(
remainingExpirationTime = NoWork;
componentUpdateQueue = null;

// Always set during createWorkInProgress
// isReRender = false;

// These were reset above
// didScheduleRenderPhaseUpdate = false;
// renderPhaseUpdates = null;
Expand Down Expand Up @@ -236,9 +247,6 @@ export function resetHooks(): void {
remainingExpirationTime = NoWork;
componentUpdateQueue = null;

// Always set during createWorkInProgress
// isReRender = false;

didScheduleRenderPhaseUpdate = false;
renderPhaseUpdates = null;
numberOfReRenders = -1;
Expand Down Expand Up @@ -272,7 +280,6 @@ function createWorkInProgressHook(): Hook {
if (workInProgressHook === null) {
// This is the first hook in the list
if (firstWorkInProgressHook === null) {
isReRender = false;
currentHook = firstCurrentHook;
if (currentHook === null) {
// This is a newly mounted hook
Expand All @@ -284,13 +291,11 @@ function createWorkInProgressHook(): Hook {
firstWorkInProgressHook = workInProgressHook;
} else {
// There's already a work-in-progress. Reuse it.
isReRender = true;
currentHook = firstCurrentHook;
workInProgressHook = firstWorkInProgressHook;
}
} else {
if (workInProgressHook.next === null) {
isReRender = false;
let hook;
if (currentHook === null) {
// This is a newly mounted hook
Expand All @@ -309,7 +314,6 @@ function createWorkInProgressHook(): Hook {
workInProgressHook = workInProgressHook.next = hook;
} else {
// There's already a work-in-progress. Reuse it.
isReRender = true;
workInProgressHook = workInProgressHook.next;
currentHook = currentHook !== null ? currentHook.next : null;
}
Expand Down Expand Up @@ -357,7 +361,7 @@ export function useReducer<S, A>(
let queue: UpdateQueue<S, A> | null = (workInProgressHook.queue: any);
if (queue !== null) {
// Already have a queue, so this is an update.
if (isReRender) {
if (numberOfReRenders > 0) {
// This is a re-render. Apply the new render phase updates to the previous
// work-in-progress hook.
const dispatch: Dispatch<A> = (queue.dispatch: any);
Expand Down
12 changes: 10 additions & 2 deletions packages/react-reconciler/src/__tests__/ReactHooksWithNoopRenderer-test.internal.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1634,7 +1634,11 @@ describe('ReactHooksWithNoopRenderer', () => {
]);

ReactNoop.render(<App loadC={true} />);
expect(ReactNoop.flush()).toEqual(['A: 2, B: 3, C: 0']);
expect(() => {
expect(ReactNoop.flush()).toEqual(['A: 2, B: 3, C: 0']);
}).toWarnDev([
'App: Rendered more hooks than during the previous render',
]);
expect(ReactNoop.getChildren()).toEqual([span('A: 2, B: 3, C: 0')]);

updateC(4);
Expand Down Expand Up @@ -1708,7 +1712,11 @@ describe('ReactHooksWithNoopRenderer', () => {
expect(ReactNoop.clearYields()).toEqual(['Mount A']);

ReactNoop.render(<App showMore={true} />);
expect(ReactNoop.flush()).toEqual([]);
expect(() => {
expect(ReactNoop.flush()).toEqual([]);
}).toWarnDev([
'App: Rendered more hooks than during the previous render',
]);
flushPassiveEffects();
expect(ReactNoop.clearYields()).toEqual(['Mount B']);

Expand Down