Add supportsMicrotasks to the host config

packages/react-art/src/ReactARTHostConfig.js

@@ -249,6 +249,7 @@ export * from 'react-reconciler/src/ReactFiberHostConfigWithNoPersistence';
 export * from 'react-reconciler/src/ReactFiberHostConfigWithNoHydration';
 export * from 'react-reconciler/src/ReactFiberHostConfigWithNoScopes';
 export * from 'react-reconciler/src/ReactFiberHostConfigWithNoTestSelectors';
+export * from 'react-reconciler/src/ReactFiberHostConfigWithNoMicrotasks';
 
 export function appendInitialChild(parentInstance, child) {
   if (typeof child === 'string') {
@@ -338,9 +339,6 @@ export function getChildHostContext() {
 export const scheduleTimeout = setTimeout;
 export const cancelTimeout = clearTimeout;
 export const noTimeout = -1;
-export function scheduleMicrotask(callback: Function) {
-  invariant(false, 'Not implemented.');
-}
 
 export function shouldSetTextContent(type, props) {
   return (

packages/react-dom/src/client/ReactDOMHostConfig.js

@@ -67,6 +67,7 @@ import {
   enableCreateEventHandleAPI,
   enableScopeAPI,
   enableNewReconciler,
+  enableDiscreteEventMicroTasks,
 } from 'shared/ReactFeatureFlags';
 import {HostComponent, HostText} from 'react-reconciler/src/ReactWorkTags';
 import {listenToAllSupportedEvents} from '../events/DOMPluginEventSystem';
@@ -399,6 +400,11 @@ export const scheduleTimeout: any =
 export const cancelTimeout: any =
   typeof clearTimeout === 'function' ? clearTimeout : (undefined: any);
 export const noTimeout = -1;
+
+// -------------------
+//     Microtasks
+// -------------------
+export const supportsMicrotasks = enableDiscreteEventMicroTasks;
 export const scheduleMicrotask: any =
   typeof queueMicrotask === 'function'
     ? queueMicrotask

packages/react-native-renderer/src/ReactFabricHostConfig.js

@@ -193,6 +193,7 @@ export * from 'react-reconciler/src/ReactFiberHostConfigWithNoMutation';
 export * from 'react-reconciler/src/ReactFiberHostConfigWithNoHydration';
 export * from 'react-reconciler/src/ReactFiberHostConfigWithNoScopes';
 export * from 'react-reconciler/src/ReactFiberHostConfigWithNoTestSelectors';
+export * from 'react-reconciler/src/ReactFiberHostConfigWithNoMicrotasks';
 
 export function appendInitialChild(
   parentInstance: Instance,
@@ -360,9 +361,6 @@ export const warnsIfNotActing = false;
 export const scheduleTimeout = setTimeout;
 export const cancelTimeout = clearTimeout;
 export const noTimeout = -1;
-export function scheduleMicrotask(callback: Function) {
-  invariant(false, 'Not implemented.');
-}
 
 // -------------------
 //     Persistence

packages/react-native-renderer/src/ReactNativeHostConfig.js

@@ -97,6 +97,7 @@ export * from 'react-reconciler/src/ReactFiberHostConfigWithNoPersistence';
 export * from 'react-reconciler/src/ReactFiberHostConfigWithNoHydration';
 export * from 'react-reconciler/src/ReactFiberHostConfigWithNoScopes';
 export * from 'react-reconciler/src/ReactFiberHostConfigWithNoTestSelectors';
+export * from 'react-reconciler/src/ReactFiberHostConfigWithNoMicrotasks';
 
 export function appendInitialChild(
   parentInstance: Instance,
@@ -255,9 +256,6 @@ export const warnsIfNotActing = true;
 export const scheduleTimeout = setTimeout;
 export const cancelTimeout = clearTimeout;
 export const noTimeout = -1;
-export function scheduleMicrotask(callback: Function) {
-  invariant(false, 'Not implemented.');
-}
 
 export function shouldSetTextContent(type: string, props: Props): boolean {
   // TODO (bvaughn) Revisit this decision.

packages/react-noop-renderer/src/createReactNoop.js

@@ -27,7 +27,10 @@ import {
   LegacyRoot,
 } from 'react-reconciler/src/ReactRootTags';
 
-import {enableNativeEventPriorityInference} from 'shared/ReactFeatureFlags';
+import {
+  enableNativeEventPriorityInference,
+  enableDiscreteEventMicroTasks,
+} from 'shared/ReactFeatureFlags';
 import ReactSharedInternals from 'shared/ReactSharedInternals';
 import enqueueTask from 'shared/enqueueTask';
 const {IsSomeRendererActing} = ReactSharedInternals;
@@ -372,6 +375,8 @@ function createReactNoop(reconciler: Function, useMutation: boolean) {
     scheduleTimeout: setTimeout,
     cancelTimeout: clearTimeout,
     noTimeout: -1,
+
+    supportsMicrotasks: enableDiscreteEventMicroTasks,
     scheduleMicrotask:
       typeof queueMicrotask === 'function'
         ? queueMicrotask

packages/react-reconciler/README.md

@@ -203,9 +203,12 @@ You can proxy this to `clearTimeout` or its equivalent in your environment.
 
 This is a property (not a function) that should be set to something that can never be a valid timeout ID. For example, you can set it to `-1`.
 
+#### `supportsMicrotask`
+
+Set this to true to indicate that your renderer supports `scheduleMicrotask`. We use microtasks as part of our discrete event implementation in React DOM. If you're not sure if your renderer should support this, you probably should. The option to not implement `scheduleMicrotask` exists so that platforms with more control over user events, like React Native, can choose to use a different mechanism.
 #### `scheduleMicrotask(fn)`
 
-You can proxy this to `queueMicrotask` or its equivalent in your environment.
+Optional. You can proxy this to `queueMicrotask` or its equivalent in your environment.
 
 #### `isPrimaryRenderer`
 

packages/react-reconciler/src/ReactFiberHostConfigWithNoMicrotasks.js

@@ -0,0 +1,26 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+import invariant from 'shared/invariant';
+
+// Renderers that don't support microtasks
+// can re-export everything from this module.
+
+function shim(...args: any) {
+  invariant(
+    false,
+    'The current renderer does not support microtasks. ' +
+      'This error is likely caused by a bug in React. ' +
+      'Please file an issue.',
+  );
+}
+
+// Test selectors (when unsupported)
+export const supportsMicrotasks = false;
+export const scheduleMicrotask = shim;

packages/react-reconciler/src/ReactFiberWorkLoop.new.js

@@ -93,8 +93,9 @@ import {
   warnsIfNotActing,
   afterActiveInstanceBlur,
   clearContainer,
-  scheduleMicrotask,
   getCurrentEventPriority,
+  supportsMicrotasks,
+  scheduleMicrotask,
 } from './ReactFiberHostConfig';
 
 import {
@@ -219,7 +220,6 @@ import {
   syncNestedUpdateFlag,
 } from './ReactProfilerTimer.new';
 
-import {enableDiscreteEventMicroTasks} from 'shared/ReactFeatureFlags';
 // DEV stuff
 import getComponentName from 'shared/getComponentName';
 import ReactStrictModeWarnings from './ReactStrictModeWarnings.new';
@@ -756,7 +756,7 @@ function ensureRootIsScheduled(root: FiberRoot, currentTime: number) {
       performSyncWorkOnRoot.bind(null, root),
     );
   } else if (
-    enableDiscreteEventMicroTasks &&
+    supportsMicrotasks &&
     newCallbackPriority === InputDiscreteLanePriority
   ) {
     scheduleMicrotask(performSyncWorkOnRoot.bind(null, root));

packages/react-reconciler/src/ReactFiberWorkLoop.old.js

@@ -93,8 +93,9 @@ import {
   warnsIfNotActing,
   afterActiveInstanceBlur,
   clearContainer,
-  scheduleMicrotask,
   getCurrentEventPriority,
+  supportsMicrotasks,
+  scheduleMicrotask,
 } from './ReactFiberHostConfig';
 
 import {
@@ -219,7 +220,6 @@ import {
   syncNestedUpdateFlag,
 } from './ReactProfilerTimer.old';
 
-import {enableDiscreteEventMicroTasks} from 'shared/ReactFeatureFlags';
 // DEV stuff
 import getComponentName from 'shared/getComponentName';
 import ReactStrictModeWarnings from './ReactStrictModeWarnings.old';
@@ -756,7 +756,7 @@ function ensureRootIsScheduled(root: FiberRoot, currentTime: number) {
       performSyncWorkOnRoot.bind(null, root),
     );
   } else if (
-    enableDiscreteEventMicroTasks &&
+    supportsMicrotasks &&
     newCallbackPriority === InputDiscreteLanePriority
   ) {
     scheduleMicrotask(performSyncWorkOnRoot.bind(null, root));

packages/react-reconciler/src/forks/ReactFiberHostConfig.custom.js

@@ -54,7 +54,6 @@ export const shouldSetTextContent = $$$hostConfig.shouldSetTextContent;
 export const createTextInstance = $$$hostConfig.createTextInstance;
 export const scheduleTimeout = $$$hostConfig.scheduleTimeout;
 export const cancelTimeout = $$$hostConfig.cancelTimeout;
-export const scheduleMicrotask = $$$hostConfig.scheduleMicrotask;
 export const noTimeout = $$$hostConfig.noTimeout;
 export const now = $$$hostConfig.now;
 export const isPrimaryRenderer = $$$hostConfig.isPrimaryRenderer;
@@ -75,6 +74,13 @@ export const prepareScopeUpdate = $$$hostConfig.preparePortalMount;
 export const getInstanceFromScope = $$$hostConfig.getInstanceFromScope;
 export const getCurrentEventPriority = $$$hostConfig.getCurrentEventPriority;
 
+// -------------------
+//      Microtasks
+//     (optional)
+// -------------------
+export const supportsMicrotasks = $$$hostConfig.supportsMicrotasks;
+export const scheduleMicrotask = $$$hostConfig.scheduleMicrotask;
+
 // -------------------
 //      Test selectors
 //     (optional)

packages/react-test-renderer/src/ReactTestHostConfig.js

@@ -58,6 +58,7 @@ export type RendererInspectionConfig = $ReadOnly<{||}>;
 export * from 'react-reconciler/src/ReactFiberHostConfigWithNoPersistence';
 export * from 'react-reconciler/src/ReactFiberHostConfigWithNoHydration';
 export * from 'react-reconciler/src/ReactFiberHostConfigWithNoTestSelectors';
+export * from 'react-reconciler/src/ReactFiberHostConfigWithNoMicrotasks';
 
 const NO_CONTEXT = {};
 const UPDATE_SIGNAL = {};
@@ -230,21 +231,7 @@ export const warnsIfNotActing = true;
 
 export const scheduleTimeout = setTimeout;
 export const cancelTimeout = clearTimeout;
-export const scheduleMicrotask =
-  typeof queueMicrotask === 'function'
-    ? queueMicrotask
-    : typeof Promise !== 'undefined'
-    ? (callback: Function) =>
-        Promise.resolve(null)
-          .then(callback)
-          .catch(handleErrorInNextTick)
-    : scheduleTimeout; // TODO: Determine the best fallback here.
-
-function handleErrorInNextTick(error) {
-  setTimeout(() => {
-    throw error;
-  });
-}
+
 export const noTimeout = -1;
 
 // -------------------

scripts/error-codes/codes.json

@@ -373,5 +373,6 @@
   "382": "This query has received more parameters than the last time the same query was used. Always pass the exact number of parameters that the query needs.",
   "383": "This query has received fewer parameters than the last time the same query was used. Always pass the exact number of parameters that the query needs.",
   "384": "Refreshing the cache is not supported in Server Components.",
-  "385": "A mutable source was mutated while the %s component was rendering. This is not supported. Move any mutations into event handlers or effects."
+  "385": "A mutable source was mutated while the %s component was rendering. This is not supported. Move any mutations into event handlers or effects.",
+  "386": "The current renderer does not support microtasks. This error is likely caused by a bug in React. Please file an issue."
 }