Put hooks behind feature flag

packages/react-reconciler/src/__tests__/ReactHooks-test.internal.js

@@ -29,6 +29,7 @@ describe('ReactHooks', () => {
     jest.resetModules();
     ReactFeatureFlags = require('shared/ReactFeatureFlags');
     ReactFeatureFlags.debugRenderPhaseSideEffectsForStrictMode = false;
+    ReactFeatureFlags.enableHooks = true;
     React = require('react');
     ReactNoop = require('react-noop-renderer');
     useState = React.useState;

packages/react-reconciler/src/__tests__/ReactNewContext-test.internal.js

@@ -21,6 +21,7 @@ describe('ReactNewContext', () => {
     jest.resetModules();
     ReactFeatureFlags = require('shared/ReactFeatureFlags');
     ReactFeatureFlags.debugRenderPhaseSideEffectsForStrictMode = false;
+    ReactFeatureFlags.enableHooks = true;
     React = require('react');
     useContext = React.useContext;
     ReactNoop = require('react-noop-renderer');

packages/react/src/React.js

@@ -13,6 +13,7 @@ import {
   REACT_STRICT_MODE_TYPE,
   REACT_SUSPENSE_TYPE,
 } from 'shared/ReactSymbols';
+import {enableHooks} from 'shared/ReactFeatureFlags';
 
 import {Component, PureComponent} from './ReactBaseClasses';
 import {createRef} from './ReactCreateRef';
@@ -63,15 +64,6 @@ const React = {
   lazy,
   memo,
 
-  useContext,
-  useState,
-  useReducer,
-  useRef,
-  useEffect,
-  useCallback,
-  useMemo,
-  useAPI,
-
   Fragment: REACT_FRAGMENT_TYPE,
   StrictMode: REACT_STRICT_MODE_TYPE,
   Suspense: REACT_SUSPENSE_TYPE,
@@ -94,4 +86,15 @@ if (enableStableConcurrentModeAPIs) {
   React.unstable_Profiler = REACT_PROFILER_TYPE;
 }
 
+if (enableHooks) {
+  React.useContext = useContext;
+  React.useState = useState;
+  React.useReducer = useReducer;
+  React.useRef = useRef;
+  React.useEffect = useEffect;
+  React.useCallback = useCallback;
+  React.useMemo = useMemo;
+  React.useAPI = useAPI;
+}
+
 export default React;

packages/shared/ReactFeatureFlags.js

@@ -9,6 +9,7 @@
 
 export const enableUserTimingAPI = __DEV__;
 
+export const enableHooks = false;
 // Helps identify side effects in begin-phase lifecycle hooks and setState reducers:
 export const debugRenderPhaseSideEffects = false;
 

packages/shared/forks/ReactFeatureFlags.native-fabric-fb.js

@@ -15,6 +15,7 @@ import typeof * as FabricFeatureFlagsType from './ReactFeatureFlags.native-fabri
 export const debugRenderPhaseSideEffects = false;
 export const debugRenderPhaseSideEffectsForStrictMode = false;
 export const enableUserTimingAPI = __DEV__;
+export const enableHooks = false;
 export const warnAboutDeprecatedLifecycles = false;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = __DEV__;
 export const enableProfilerTimer = __PROFILE__;

packages/shared/forks/ReactFeatureFlags.native-fabric-oss.js

@@ -15,6 +15,7 @@ import typeof * as FabricFeatureFlagsType from './ReactFeatureFlags.native-fabri
 export const debugRenderPhaseSideEffects = false;
 export const debugRenderPhaseSideEffectsForStrictMode = false;
 export const enableUserTimingAPI = __DEV__;
+export const enableHooks = false;
 export const warnAboutDeprecatedLifecycles = false;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = __DEV__;
 export const enableProfilerTimer = __PROFILE__;

packages/shared/forks/ReactFeatureFlags.native-fb.js

@@ -14,6 +14,7 @@ import typeof * as FeatureFlagsShimType from './ReactFeatureFlags.native-fb';
 
 // Re-export dynamic flags from the fbsource version.
 export const {
+  enableHooks,
   debugRenderPhaseSideEffects,
   debugRenderPhaseSideEffectsForStrictMode,
   warnAboutDeprecatedLifecycles,

packages/shared/forks/ReactFeatureFlags.native-oss.js

@@ -14,6 +14,7 @@ import typeof * as FeatureFlagsShimType from './ReactFeatureFlags.native-oss';
 
 export const debugRenderPhaseSideEffects = false;
 export const debugRenderPhaseSideEffectsForStrictMode = false;
+export const enableHooks = false;
 export const enableUserTimingAPI = __DEV__;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = __DEV__;
 export const warnAboutDeprecatedLifecycles = false;

packages/shared/forks/ReactFeatureFlags.persistent.js

@@ -15,6 +15,7 @@ import typeof * as PersistentFeatureFlagsType from './ReactFeatureFlags.persiste
 export const debugRenderPhaseSideEffects = false;
 export const debugRenderPhaseSideEffectsForStrictMode = false;
 export const enableUserTimingAPI = __DEV__;
+export const enableHooks = false;
 export const warnAboutDeprecatedLifecycles = false;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = __DEV__;
 export const enableProfilerTimer = __PROFILE__;

packages/shared/forks/ReactFeatureFlags.test-renderer.js

@@ -15,6 +15,7 @@ import typeof * as PersistentFeatureFlagsType from './ReactFeatureFlags.persiste
 export const debugRenderPhaseSideEffects = false;
 export const debugRenderPhaseSideEffectsForStrictMode = false;
 export const enableUserTimingAPI = __DEV__;
+export const enableHooks = false;
 export const warnAboutDeprecatedLifecycles = false;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = false;
 export const enableProfilerTimer = false;

packages/shared/forks/ReactFeatureFlags.test-renderer.www.js

@@ -15,6 +15,7 @@ import typeof * as PersistentFeatureFlagsType from './ReactFeatureFlags.persiste
 export const debugRenderPhaseSideEffects = false;
 export const debugRenderPhaseSideEffectsForStrictMode = false;
 export const enableUserTimingAPI = __DEV__;
+export const enableHooks = false;
 export const warnAboutDeprecatedLifecycles = false;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = false;
 export const enableProfilerTimer = false;

packages/shared/forks/ReactFeatureFlags.www.js

@@ -20,6 +20,9 @@ export const {
   disableInputAttributeSyncing,
 } = require('ReactFeatureFlags');
 
+// The rest of the flags are static for better dead code elimination.
+export const enableHooks = false;
+
 // In www, we have experimental support for gathering data
 // from User Timing API calls in production. By default, we
 // only emit performance.mark/measure calls in __DEV__. But if