DCE hooks code when flag is off

Author: sophiebits

packages/react-dom/src/server/ReactPartialRenderer.js

@@ -25,6 +25,7 @@ import describeComponentFrame from 'shared/describeComponentFrame';
 import ReactSharedInternals from 'shared/ReactSharedInternals';
 import {
   warnAboutDeprecatedLifecycles,
+  enableHooks,
   enableSuspenseServerRenderer,
 } from 'shared/ReactFeatureFlags';
 
@@ -52,6 +53,7 @@ import {
   prepareToUseHooks,
   finishHooks,
   Dispatcher,
+  DispatcherWithoutHooks,
 } from './ReactPartialRendererHooks';
 import {
   Namespaces,
@@ -819,7 +821,11 @@ class ReactDOMServerRenderer {
       return null;
     }
 
-    ReactCurrentOwner.currentDispatcher = Dispatcher;
+    if (enableHooks) {
+      ReactCurrentOwner.currentDispatcher = Dispatcher;
+    } else {
+      ReactCurrentOwner.currentDispatcher = DispatcherWithoutHooks;
+    }
     try {
       let out = '';
       while (out.length < bytes) {

packages/react-dom/src/server/ReactPartialRendererHooks.js

@@ -350,3 +350,6 @@ export const Dispatcher = {
   // Effects are not run in the server environment.
   useEffect: noop,
 };
+export const DispatcherWithoutHooks = {
+  readContext,
+};

packages/react-reconciler/src/ReactFiberDispatcher.js

@@ -34,3 +34,6 @@ export const Dispatcher = {
   useRef,
   useState,
 };
+export const DispatcherWithoutHooks = {
+  readContext,
+};

packages/react-reconciler/src/ReactFiberScheduler.js

@@ -56,6 +56,7 @@ import {
   SimpleMemoComponent,
 } from 'shared/ReactWorkTags';
 import {
+  enableHooks
   enableSchedulerTracing,
   enableProfilerTimer,
   enableUserTimingAPI,
@@ -164,7 +165,7 @@ import {
   commitDetachRef,
   commitPassiveHookEffects,
 } from './ReactFiberCommitWork';
-import {Dispatcher} from './ReactFiberDispatcher';
+import {Dispatcher, DispatcherWithoutHooks} from './ReactFiberDispatcher';
 
 export type Thenable = {
   then(resolve: () => mixed, reject?: () => mixed): mixed,
@@ -1192,7 +1193,11 @@ function renderRoot(root: FiberRoot, isYieldy: boolean): void {
   flushPassiveEffects();
 
   isWorking = true;
-  ReactCurrentOwner.currentDispatcher = Dispatcher;
+  if (enableHooks) {
+    ReactCurrentOwner.currentDispatcher = Dispatcher;
+  } else {
+    ReactCurrentOwner.currentDispatcher = DispatcherWithoutHooks;
+  }
 
   const expirationTime = root.nextExpirationTimeToWorkOn;
 

scripts/rollup/results.json

@@ -53,8 +53,8 @@
       "filename": "react-dom.production.min.js",
       "bundleType": "UMD_PROD",
       "packageName": "react-dom",
-      "size": 100367,
-      "gzip": 32791
+      "size": 105387,
+      "gzip": 34584
     },
     {
       "filename": "react-dom.development.js",