Don't bailout after Suspending in Legacy Mode

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

@@ -63,6 +63,7 @@ import {
   Update,
   Ref,
   Deletion,
+  ForceUpdateForLegacySuspense,
 } from './ReactSideEffectTags';
 import ReactSharedInternals from 'shared/ReactSharedInternals';
 import {
@@ -548,6 +549,13 @@ function updateSimpleMemoComponent(
           workInProgress,
           renderLanes,
         );
+      } else if (
+        (current.effectTag & ForceUpdateForLegacySuspense) !==
+        NoEffect
+      ) {
+        // This is a special case that only exists for legacy mode.
+        // See https://github.com/facebook/react/pull/19216.
+        didReceiveUpdate = true;
       }
     }
   }
@@ -3253,11 +3261,17 @@ function beginWork(
       }
       return bailoutOnAlreadyFinishedWork(current, workInProgress, renderLanes);
     } else {
-      // An update was scheduled on this fiber, but there are no new props
-      // nor legacy context. Set this to false. If an update queue or context
-      // consumer produces a changed value, it will set this to true. Otherwise,
-      // the component will assume the children have not changed and bail out.
-      didReceiveUpdate = false;
+      if ((current.effectTag & ForceUpdateForLegacySuspense) !== NoEffect) {
+        // This is a special case that only exists for legacy mode.
+        // See https://github.com/facebook/react/pull/19216.
+        didReceiveUpdate = true;
+      } else {
+        // An update was scheduled on this fiber, but there are no new props
+        // nor legacy context. Set this to false. If an update queue or context
+        // consumer produces a changed value, it will set this to true. Otherwise,
+        // the component will assume the children have not changed and bail out.
+        didReceiveUpdate = false;
+      }
     }
   } else {
     didReceiveUpdate = false;

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

@@ -63,6 +63,7 @@ import {
   Update,
   Ref,
   Deletion,
+  ForceUpdateForLegacySuspense,
 } from './ReactSideEffectTags';
 import ReactSharedInternals from 'shared/ReactSharedInternals';
 import {
@@ -548,6 +549,13 @@ function updateSimpleMemoComponent(
           workInProgress,
           renderLanes,
         );
+      } else if (
+        (current.effectTag & ForceUpdateForLegacySuspense) !==
+        NoEffect
+      ) {
+        // This is a special case that only exists for legacy mode.
+        // See https://github.com/facebook/react/pull/19216.
+        didReceiveUpdate = true;
       }
     }
   }
@@ -3253,11 +3261,17 @@ function beginWork(
       }
       return bailoutOnAlreadyFinishedWork(current, workInProgress, renderLanes);
     } else {
-      // An update was scheduled on this fiber, but there are no new props
-      // nor legacy context. Set this to false. If an update queue or context
-      // consumer produces a changed value, it will set this to true. Otherwise,
-      // the component will assume the children have not changed and bail out.
-      didReceiveUpdate = false;
+      if ((current.effectTag & ForceUpdateForLegacySuspense) !== NoEffect) {
+        // This is a special case that only exists for legacy mode.
+        // See https://github.com/facebook/react/pull/19216.
+        didReceiveUpdate = true;
+      } else {
+        // An update was scheduled on this fiber, but there are no new props
+        // nor legacy context. Set this to false. If an update queue or context
+        // consumer produces a changed value, it will set this to true. Otherwise,
+        // the component will assume the children have not changed and bail out.
+        didReceiveUpdate = false;
+      }
     }
   } else {
     didReceiveUpdate = false;

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

@@ -28,6 +28,7 @@ import {
   NoEffect,
   ShouldCapture,
   LifecycleEffectMask,
+  ForceUpdateForLegacySuspense,
 } from './ReactSideEffectTags';
 import {shouldCaptureSuspense} from './ReactFiberSuspenseComponent.new';
 import {NoMode, BlockingMode} from './ReactTypeOfMode';
@@ -238,6 +239,7 @@ function throwException(
         // should *not* suspend the commit.
         if ((workInProgress.mode & BlockingMode) === NoMode) {
           workInProgress.effectTag |= DidCapture;
+          sourceFiber.effectTag |= ForceUpdateForLegacySuspense;
 
           // We're going to commit this fiber even though it didn't complete.
           // But we shouldn't call any lifecycle methods or callbacks. Remove

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

@@ -28,6 +28,7 @@ import {
   NoEffect,
   ShouldCapture,
   LifecycleEffectMask,
+  ForceUpdateForLegacySuspense,
 } from './ReactSideEffectTags';
 import {shouldCaptureSuspense} from './ReactFiberSuspenseComponent.old';
 import {NoMode, BlockingMode, DebugTracingMode} from './ReactTypeOfMode';
@@ -249,6 +250,7 @@ function throwException(
         // should *not* suspend the commit.
         if ((workInProgress.mode & BlockingMode) === NoMode) {
           workInProgress.effectTag |= DidCapture;
+          sourceFiber.effectTag |= ForceUpdateForLegacySuspense;
 
           // We're going to commit this fiber even though it didn't complete.
           // But we shouldn't call any lifecycle methods or callbacks. Remove

packages/react-reconciler/src/ReactSideEffectTags.js

@@ -10,29 +10,31 @@
 export type SideEffectTag = number;
 
 // Don't change these two values. They're used by React Dev Tools.
-export const NoEffect = /*                 */ 0b00000000000000;
-export const PerformedWork = /*            */ 0b00000000000001;
+export const NoEffect = /*                     */ 0b000000000000000;
+export const PerformedWork = /*                */ 0b000000000000001;
 
 // You can change the rest (and add more).
-export const Placement = /*                */ 0b00000000000010;
-export const Update = /*                   */ 0b00000000000100;
-export const PlacementAndUpdate = /*       */ 0b00000000000110;
-export const Deletion = /*                 */ 0b00000000001000;
-export const ContentReset = /*             */ 0b00000000010000;
-export const Callback = /*                 */ 0b00000000100000;
-export const DidCapture = /*               */ 0b00000001000000;
-export const Ref = /*                      */ 0b00000010000000;
-export const Snapshot = /*                 */ 0b00000100000000;
-export const Passive = /*                  */ 0b00001000000000;
-export const PassiveUnmountPendingDev = /* */ 0b10000000000000;
-export const Hydrating = /*                */ 0b00010000000000;
-export const HydratingAndUpdate = /*       */ 0b00010000000100;
+export const Placement = /*                    */ 0b000000000000010;
+export const Update = /*                       */ 0b000000000000100;
+export const PlacementAndUpdate = /*           */ 0b000000000000110;
+export const Deletion = /*                     */ 0b000000000001000;
+export const ContentReset = /*                 */ 0b000000000010000;
+export const Callback = /*                     */ 0b000000000100000;
+export const DidCapture = /*                   */ 0b000000001000000;
+export const Ref = /*                          */ 0b000000010000000;
+export const Snapshot = /*                     */ 0b000000100000000;
+export const Passive = /*                      */ 0b000001000000000;
+export const PassiveUnmountPendingDev = /*     */ 0b010000000000000;
+export const Hydrating = /*                    */ 0b000010000000000;
+export const HydratingAndUpdate = /*           */ 0b000010000000100;
 
 // Passive & Update & Callback & Ref & Snapshot
-export const LifecycleEffectMask = /*      */ 0b00001110100100;
+export const LifecycleEffectMask = /*          */ 0b000001110100100;
 
 // Union of all host effects
-export const HostEffectMask = /*           */ 0b00011111111111;
+export const HostEffectMask = /*               */ 0b000011111111111;
 
-export const Incomplete = /*               */ 0b00100000000000;
-export const ShouldCapture = /*            */ 0b01000000000000;
+// These are not really side effects, but we still reuse this field.
+export const Incomplete = /*                   */ 0b000100000000000;
+export const ShouldCapture = /*                */ 0b001000000000000;
+export const ForceUpdateForLegacySuspense = /* */ 0b100000000000000;

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

@@ -803,7 +803,7 @@ describe('ReactSuspense', () => {
 
     const ValueContext = createContext(null);
 
-    let MemoizedChild = forwardRef(() => {
+    const MemoizedChild = forwardRef(() => {
       const text = useContext(ValueContext);
       try {
         TextResource.read([text, 1000]);