Revert #24236 (Don't recreate the same fallback on the client if hydr…

…ating suspends) (#24434)

* Revert #24236 (Don't recreate the same fallback on the client if hydrating suspends)

* Use @GATE FIXME

packages/react-dom/src/__tests__/ReactDOMFizzServer-test.js

@@ -869,16 +869,15 @@ describe('ReactDOMFizzServer', () => {
     });
 
     // We still can't render it on the client.
-    expect(Scheduler).toFlushAndYield([]);
-    expect(getVisibleChildren(container)).toEqual(<div>Loading...</div>);
-
-    // We now resolve it on the client.
-    resolveText('Hello');
-
     expect(Scheduler).toFlushAndYield([
       'The server could not finish this Suspense boundary, likely due to an ' +
         'error during server rendering. Switched to client rendering.',
     ]);
+    expect(getVisibleChildren(container)).toEqual(<div>Loading...</div>);
+
+    // We now resolve it on the client.
+    resolveText('Hello');
+    Scheduler.unstable_flushAll();
 
     // The client rendered HTML is now in place.
     expect(getVisibleChildren(container)).toEqual(
@@ -2189,7 +2188,10 @@ describe('ReactDOMFizzServer', () => {
     },
   );
 
+  // Disabled because of a WWW late mutations regression.
+  // We may want to re-enable this if we figure out why.
   // @gate experimental
+  // @gate FIXME
   it('does not recreate the fallback if server errors and hydration suspends', async () => {
     let isClient = false;
 
@@ -2268,7 +2270,10 @@ describe('ReactDOMFizzServer', () => {
     );
   });
 
+  // Disabled because of a WWW late mutations regression.
+  // We may want to re-enable this if we figure out why.
   // @gate experimental
+  // @gate FIXME
   it(
     'does not recreate the fallback if server errors and hydration suspends ' +
       'and root receives a transition',
@@ -2364,7 +2369,10 @@ describe('ReactDOMFizzServer', () => {
     },
   );
 
+  // Disabled because of a WWW late mutations regression.
+  // We may want to re-enable this if we figure out why.
   // @gate experimental
+  // @gate FIXME
   it(
     'recreates the fallback if server errors and hydration suspends but ' +
       'client receives new props',
@@ -2542,25 +2550,25 @@ describe('ReactDOMFizzServer', () => {
         },
       });
 
-      // An error happened but instead of surfacing it to the UI, we suspended.
-      expect(Scheduler).toFlushAndYield([]);
+      // An error logged but instead of surfacing it to the UI, we switched
+      // to client rendering.
+      expect(Scheduler).toFlushAndYield([
+        'Hydration error',
+        'There was an error while hydrating this Suspense boundary. Switched ' +
+          'to client rendering.',
+      ]);
       expect(getVisibleChildren(container)).toEqual(
         <div>
           <span />
-          <span>Yay!</span>
+          Loading...
           <span />
         </div>,
       );
 
       await act(async () => {
         resolveText('Yay!');
       });
-      expect(Scheduler).toFlushAndYield([
-        'Yay!',
-        'Hydration error',
-        'There was an error while hydrating this Suspense boundary. Switched ' +
-          'to client rendering.',
-      ]);
+      expect(Scheduler).toFlushAndYield(['Yay!']);
       expect(getVisibleChildren(container)).toEqual(
         <div>
           <span />

packages/react-dom/src/__tests__/ReactDOMHydrationDiff-test.js

@@ -792,7 +792,7 @@ describe('ReactDOMServerHydration', () => {
       });
 
       // @gate __DEV__
-      it('does not warn when client renders an extra node inside Suspense fallback', () => {
+      it('warns when client renders an extra node inside Suspense fallback', () => {
         function Mismatch({isClient}) {
           return (
             <div className="parent">
@@ -809,12 +809,15 @@ describe('ReactDOMServerHydration', () => {
             </div>
           );
         }
-        // There is no error because we don't actually hydrate fallbacks.
-        expect(testMismatch(Mismatch)).toMatchInlineSnapshot(`Array []`);
+        expect(testMismatch(Mismatch)).toMatchInlineSnapshot(`
+          Array [
+            "Caught [The server could not finish this Suspense boundary, likely due to an error during server rendering. Switched to client rendering.]",
+          ]
+        `);
       });
 
       // @gate __DEV__
-      it('does not warn when server renders an extra node inside Suspense fallback', () => {
+      it('warns when server renders an extra node inside Suspense fallback', () => {
         function Mismatch({isClient}) {
           return (
             <div className="parent">
@@ -831,8 +834,11 @@ describe('ReactDOMServerHydration', () => {
             </div>
           );
         }
-        // There is no error because we don't actually hydrate fallbacks.
-        expect(testMismatch(Mismatch)).toMatchInlineSnapshot(`Array []`);
+        expect(testMismatch(Mismatch)).toMatchInlineSnapshot(`
+          Array [
+            "Caught [The server could not finish this Suspense boundary, likely due to an error during server rendering. Switched to client rendering.]",
+          ]
+        `);
       });
     });
 

packages/react-dom/src/__tests__/ReactDOMServerPartialHydration-test.internal.js

@@ -2115,7 +2115,10 @@ describe('ReactDOMServerPartialHydration', () => {
     });
 
     suspend = true;
-    expect(Scheduler).toFlushAndYield([]);
+    expect(Scheduler).toFlushAndYield([
+      'The server could not finish this Suspense boundary, likely due to ' +
+        'an error during server rendering. Switched to client rendering.',
+    ]);
 
     // We haven't hydrated the second child but the placeholder is still in the list.
     expect(container.textContent).toBe('ALoading B');

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

@@ -2270,7 +2270,6 @@ function updateSuspenseComponent(current, workInProgress, renderLanes) {
         } else {
           // Suspended but we should no longer be in dehydrated mode.
           // Therefore we now have to render the fallback.
-          renderDidSuspendDelayIfPossible();
           const nextPrimaryChildren = nextProps.children;
           const nextFallbackChildren = nextProps.fallback;
           const fallbackChildFragment = mountSuspenseFallbackAfterRetryWithoutHydrating(

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

@@ -2270,7 +2270,6 @@ function updateSuspenseComponent(current, workInProgress, renderLanes) {
         } else {
           // Suspended but we should no longer be in dehydrated mode.
           // Therefore we now have to render the fallback.
-          renderDidSuspendDelayIfPossible();
           const nextPrimaryChildren = nextProps.children;
           const nextFallbackChildren = nextProps.fallback;
           const fallbackChildFragment = mountSuspenseFallbackAfterRetryWithoutHydrating(

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

@@ -459,6 +459,9 @@ export function includesOnlyNonUrgentLanes(lanes: Lanes) {
   const UrgentLanes = SyncLane | InputContinuousLane | DefaultLane;
   return (lanes & UrgentLanes) === NoLanes;
 }
+export function includesOnlyTransitions(lanes: Lanes) {
+  return (lanes & TransitionLanes) === lanes;
+}
 
 export function includesBlockingLane(root: FiberRoot, lanes: Lanes) {
   if (

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

@@ -459,6 +459,9 @@ export function includesOnlyNonUrgentLanes(lanes: Lanes) {
   const UrgentLanes = SyncLane | InputContinuousLane | DefaultLane;
   return (lanes & UrgentLanes) === NoLanes;
 }
+export function includesOnlyTransitions(lanes: Lanes) {
+  return (lanes & TransitionLanes) === lanes;
+}
 
 export function includesBlockingLane(root: FiberRoot, lanes: Lanes) {
   if (

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

@@ -131,7 +131,7 @@ import {
   pickArbitraryLane,
   includesNonIdleWork,
   includesOnlyRetries,
-  includesOnlyNonUrgentLanes,
+  includesOnlyTransitions,
   includesBlockingLane,
   includesExpiredLane,
   getNextLanes,
@@ -1150,7 +1150,7 @@ function finishConcurrentRender(root, exitStatus, lanes) {
     case RootSuspendedWithDelay: {
       markRootSuspended(root, lanes);
 
-      if (includesOnlyNonUrgentLanes(lanes)) {
+      if (includesOnlyTransitions(lanes)) {
         // This is a transition, so we should exit without committing a
         // placeholder and without scheduling a timeout. Delay indefinitely
         // until we receive more data.

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

@@ -131,7 +131,7 @@ import {
   pickArbitraryLane,
   includesNonIdleWork,
   includesOnlyRetries,
-  includesOnlyNonUrgentLanes,
+  includesOnlyTransitions,
   includesBlockingLane,
   includesExpiredLane,
   getNextLanes,
@@ -1150,7 +1150,7 @@ function finishConcurrentRender(root, exitStatus, lanes) {
     case RootSuspendedWithDelay: {
       markRootSuspended(root, lanes);
 
-      if (includesOnlyNonUrgentLanes(lanes)) {
+      if (includesOnlyTransitions(lanes)) {
         // This is a transition, so we should exit without committing a
         // placeholder and without scheduling a timeout. Delay indefinitely
         // until we receive more data.