Reset new fork to old fork (#20254)

* Fix typo

This typo was fixed in the new fork but not the old.

* Reset new fork to old fork

Something in the new fork is causing a topline metrics regression. We're
not sure what it is, so we're going to split it into steps and bisect.

As a first step, this resets the new fork back to the contents of the
old fork. We will land this to confirm that the fork infra itself is
not causing a regression.

* Fix tests: Add `dfsEffectsRefactor` flag

Some of the tests that gated on the effects refactor used the `new`
flag. In order to bisect, we'll need to decompose the new fork changes
into multiple steps.

So I added a hardcoded test flag called `dfsEffectsRefactor` and set it
to false. Will turn back on when we switch back to traversing the
finished tree using DFS and `subtreeTag`.

Author: acdlite

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

@@ -367,7 +367,7 @@ describe('ReactDOMServerPartialHydration', () => {
     // This is a new node.
     expect(span).not.toBe(span2);
 
-    if (gate(flags => flags.new)) {
+    if (gate(flags => flags.dfsEffectsRefactor)) {
       // The effects list refactor causes this to be null because the Suspense Offscreen's child
       // is null. However, since we can't hydrate Suspense in legacy this change in behavior is ok
       expect(ref.current).toBe(null);

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

@@ -16,6 +16,7 @@ beforeEach(() => {
 });
 
 // Don't feel too guilty if you have to delete this test.
+// @gate dfsEffectsRefactor
 // @gate new
 // @gate __DEV__
 test('warns in DEV if return pointer is inconsistent', async () => {

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

@@ -13,7 +13,7 @@ import type {Fiber} from './ReactInternalTypes';
 import type {Lanes} from './ReactFiberLane';
 
 import getComponentName from 'shared/getComponentName';
-import {Deletion, Placement} from './ReactFiberFlags';
+import {Placement, Deletion} from './ReactFiberFlags';
 import {
   getIteratorFn,
   REACT_ELEMENT_TYPE,
@@ -256,13 +256,20 @@ function ChildReconciler(shouldTrackSideEffects) {
       // Noop.
       return;
     }
-    const deletions = returnFiber.deletions;
-    if (deletions === null) {
-      returnFiber.deletions = [childToDelete];
-      returnFiber.flags |= Deletion;
+    // Deletions are added in reversed order so we add it to the front.
+    // At this point, the return fiber's effect list is empty except for
+    // deletions, so we can just append the deletion to the list. The remaining
+    // effects aren't added until the complete phase. Once we implement
+    // resuming, this may not be true.
+    const last = returnFiber.lastEffect;
+    if (last !== null) {
+      last.nextEffect = childToDelete;
+      returnFiber.lastEffect = childToDelete;
     } else {
-      deletions.push(childToDelete);
+      returnFiber.firstEffect = returnFiber.lastEffect = childToDelete;
     }
+    childToDelete.nextEffect = null;
+    childToDelete.flags = Deletion;
   }
 
   function deleteRemainingChildren(

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

@@ -28,7 +28,7 @@ import {
   enableFundamentalAPI,
   enableScopeAPI,
 } from 'shared/ReactFeatureFlags';
-import {NoFlags, Placement, StaticMask} from './ReactFiberFlags';
+import {NoFlags, Placement} from './ReactFiberFlags';
 import {ConcurrentRoot, BlockingRoot} from './ReactRootTags';
 import {
   IndeterminateComponent,
@@ -279,6 +279,13 @@ export function createWorkInProgress(current: Fiber, pendingProps: any): Fiber {
     workInProgress.type = current.type;
 
     // We already have an alternate.
+    // Reset the effect tag.
+    workInProgress.flags = NoFlags;
+
+    // The effect list is no longer valid.
+    workInProgress.nextEffect = null;
+    workInProgress.firstEffect = null;
+    workInProgress.lastEffect = null;
     workInProgress.subtreeFlags = NoFlags;
     workInProgress.deletions = null;
 
@@ -292,9 +299,6 @@ export function createWorkInProgress(current: Fiber, pendingProps: any): Fiber {
     }
   }
 
-  // Reset all effects except static ones.
-  // Static effects are not specific to a render.
-  workInProgress.flags = current.flags & StaticMask;
   workInProgress.childLanes = current.childLanes;
   workInProgress.lanes = current.lanes;
 
@@ -360,6 +364,11 @@ export function resetWorkInProgress(workInProgress: Fiber, renderLanes: Lanes) {
   // that child fiber is setting, not the reconciliation.
   workInProgress.flags &= Placement;
 
+  // The effect list is no longer valid.
+  workInProgress.nextEffect = null;
+  workInProgress.firstEffect = null;
+  workInProgress.lastEffect = null;
+
   const current = workInProgress.alternate;
   if (current === null) {
     // Reset to createFiber's initial values.

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

@@ -58,10 +58,10 @@ import {
   Hydrating,
   ContentReset,
   DidCapture,
+  Update,
   Ref,
   Deletion,
   ForceUpdateForLegacySuspense,
-  StaticMask,
 } from './ReactFiberFlags';
 import ReactSharedInternals from 'shared/ReactSharedInternals';
 import {
@@ -671,6 +671,8 @@ function updateProfiler(
   renderLanes: Lanes,
 ) {
   if (enableProfilerTimer) {
+    workInProgress.flags |= Update;
+
     // Reset effect durations for the next eventual effect phase.
     // These are reset during render to allow the DevTools commit hook a chance to read them,
     const stateNode = workInProgress.stateNode;
@@ -1077,9 +1079,6 @@ function updateHostComponent(
     workInProgress.flags |= ContentReset;
   }
 
-  // React DevTools reads this flag.
-  workInProgress.flags |= PerformedWork;
-
   markRef(current, workInProgress);
   reconcileChildren(current, workInProgress, nextChildren, renderLanes);
   return workInProgress.child;
@@ -2005,14 +2004,9 @@ function updateSuspensePrimaryChildren(
   primaryChildFragment.sibling = null;
   if (currentFallbackChildFragment !== null) {
     // Delete the fallback child fragment
-    const deletions = workInProgress.deletions;
-    if (deletions === null) {
-      workInProgress.deletions = [currentFallbackChildFragment];
-      // TODO (effects) Rename this to better reflect its new usage (e.g. ChildDeletions)
-      workInProgress.flags |= Deletion;
-    } else {
-      deletions.push(currentFallbackChildFragment);
-    }
+    currentFallbackChildFragment.nextEffect = null;
+    currentFallbackChildFragment.flags = Deletion;
+    workInProgress.firstEffect = workInProgress.lastEffect = currentFallbackChildFragment;
   }
 
   workInProgress.child = primaryChildFragment;
@@ -2069,19 +2063,24 @@ function updateSuspenseFallbackChildren(
 
     // The fallback fiber was added as a deletion effect during the first pass.
     // However, since we're going to remain on the fallback, we no longer want
-    // to delete it.
-    workInProgress.deletions = null;
+    // to delete it. So we need to remove it from the list. Deletions are stored
+    // on the same list as effects. We want to keep the effects from the primary
+    // tree. So we copy the primary child fragment's effect list, which does not
+    // include the fallback deletion effect.
+    const progressedLastEffect = primaryChildFragment.lastEffect;
+    if (progressedLastEffect !== null) {
+      workInProgress.firstEffect = primaryChildFragment.firstEffect;
+      workInProgress.lastEffect = progressedLastEffect;
+      progressedLastEffect.nextEffect = null;
+    } else {
+      // TODO: Reset this somewhere else? Lol legacy mode is so weird.
+      workInProgress.firstEffect = workInProgress.lastEffect = null;
+    }
   } else {
     primaryChildFragment = createWorkInProgressOffscreenFiber(
       currentPrimaryChildFragment,
       primaryChildProps,
     );
-
-    // Since we're reusing a current tree, we need to reuse the flags, too.
-    // (We don't do this in legacy mode, because in legacy mode we don't re-use
-    // the current tree; see previous branch.)
-    primaryChildFragment.subtreeFlags =
-      currentPrimaryChildFragment.subtreeFlags & StaticMask;
   }
   let fallbackChildFragment;
   if (currentFallbackChildFragment !== null) {
@@ -2566,6 +2565,7 @@ function initSuspenseListRenderState(
   tail: null | Fiber,
   lastContentRow: null | Fiber,
   tailMode: SuspenseListTailMode,
+  lastEffectBeforeRendering: null | Fiber,
 ): void {
   const renderState: null | SuspenseListRenderState =
     workInProgress.memoizedState;
@@ -2577,6 +2577,7 @@ function initSuspenseListRenderState(
       last: lastContentRow,
       tail: tail,
       tailMode: tailMode,
+      lastEffect: lastEffectBeforeRendering,
     }: SuspenseListRenderState);
   } else {
     // We can reuse the existing object from previous renders.
@@ -2586,6 +2587,7 @@ function initSuspenseListRenderState(
     renderState.last = lastContentRow;
     renderState.tail = tail;
     renderState.tailMode = tailMode;
+    renderState.lastEffect = lastEffectBeforeRendering;
   }
 }
 
@@ -2667,6 +2669,7 @@ function updateSuspenseListComponent(
           tail,
           lastContentRow,
           tailMode,
+          workInProgress.lastEffect,
         );
         break;
       }
@@ -2698,6 +2701,7 @@ function updateSuspenseListComponent(
           tail,
           null, // last
           tailMode,
+          workInProgress.lastEffect,
         );
         break;
       }
@@ -2708,6 +2712,7 @@ function updateSuspenseListComponent(
           null, // tail
           null, // last
           undefined,
+          workInProgress.lastEffect,
         );
         break;
       }
@@ -2967,14 +2972,15 @@ function remountFiber(
 
     // Delete the old fiber and place the new one.
     // Since the old fiber is disconnected, we have to schedule it manually.
-    const deletions = returnFiber.deletions;
-    if (deletions === null) {
-      returnFiber.deletions = [current];
-      // TODO (effects) Rename this to better reflect its new usage (e.g. ChildDeletions)
-      returnFiber.flags |= Deletion;
+    const last = returnFiber.lastEffect;
+    if (last !== null) {
+      last.nextEffect = current;
+      returnFiber.lastEffect = current;
     } else {
-      deletions.push(current);
+      returnFiber.firstEffect = returnFiber.lastEffect = current;
     }
+    current.nextEffect = null;
+    current.flags = Deletion;
 
     newWorkInProgress.flags |= Placement;
 
@@ -3059,6 +3065,15 @@ function beginWork(
         }
         case Profiler:
           if (enableProfilerTimer) {
+            // Profiler should only call onRender when one of its descendants actually rendered.
+            const hasChildWork = includesSomeLane(
+              renderLanes,
+              workInProgress.childLanes,
+            );
+            if (hasChildWork) {
+              workInProgress.flags |= Update;
+            }
+
             // Reset effect durations for the next eventual effect phase.
             // These are reset during render to allow the DevTools commit hook a chance to read them,
             const stateNode = workInProgress.stateNode;
@@ -3165,6 +3180,7 @@ function beginWork(
             // update in the past but didn't complete it.
             renderState.rendering = null;
             renderState.tail = null;
+            renderState.lastEffect = null;
           }
           pushSuspenseContext(workInProgress, suspenseStackCursor.current);
 

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

@@ -12,14 +12,13 @@ import type {Lanes} from './ReactFiberLane';
 import type {UpdateQueue} from './ReactUpdateQueue.new';
 
 import * as React from 'react';
-import {Update, Snapshot, MountLayoutDev} from './ReactFiberFlags';
+import {Update, Snapshot} from './ReactFiberFlags';
 import {
   debugRenderPhaseSideEffectsForStrictMode,
   disableLegacyContext,
   enableDebugTracing,
   enableSchedulingProfiler,
   warnAboutDeprecatedLifecycles,
-  enableDoubleInvokingEffects,
 } from 'shared/ReactFeatureFlags';
 import ReactStrictModeWarnings from './ReactStrictModeWarnings.new';
 import {isMounted} from './ReactFiberTreeReflection';
@@ -30,13 +29,7 @@ import invariant from 'shared/invariant';
 import {REACT_CONTEXT_TYPE, REACT_PROVIDER_TYPE} from 'shared/ReactSymbols';
 
 import {resolveDefaultProps} from './ReactFiberLazyComponent.new';
-import {
-  BlockingMode,
-  ConcurrentMode,
-  DebugTracingMode,
-  NoMode,
-  StrictMode,
-} from './ReactTypeOfMode';
+import {DebugTracingMode, StrictMode} from './ReactTypeOfMode';
 
 import {
   enqueueUpdate,
@@ -897,16 +890,7 @@ function mountClassInstance(
   }
 
   if (typeof instance.componentDidMount === 'function') {
-    if (
-      __DEV__ &&
-      enableDoubleInvokingEffects &&
-      (workInProgress.mode & (BlockingMode | ConcurrentMode)) !== NoMode
-    ) {
-      // Never double-invoke effects for legacy roots.
-      workInProgress.flags |= MountLayoutDev | Update;
-    } else {
-      workInProgress.flags |= Update;
-    }
+    workInProgress.flags |= Update;
   }
 }
 
@@ -976,15 +960,7 @@ function resumeMountClassInstance(
     // If an update was already in progress, we should schedule an Update
     // effect even though we're bailing out, so that cWU/cDU are called.
     if (typeof instance.componentDidMount === 'function') {
-      if (
-        __DEV__ &&
-        enableDoubleInvokingEffects &&
-        (workInProgress.mode & (BlockingMode | ConcurrentMode)) !== NoMode
-      ) {
-        workInProgress.flags |= MountLayoutDev | Update;
-      } else {
-        workInProgress.flags |= Update;
-      }
+      workInProgress.flags |= Update;
     }
     return false;
   }
@@ -1027,29 +1003,13 @@ function resumeMountClassInstance(
       }
     }
     if (typeof instance.componentDidMount === 'function') {
-      if (
-        __DEV__ &&
-        enableDoubleInvokingEffects &&
-        (workInProgress.mode & (BlockingMode | ConcurrentMode)) !== NoMode
-      ) {
-        workInProgress.flags |= MountLayoutDev | Update;
-      } else {
-        workInProgress.flags |= Update;
-      }
+      workInProgress.flags |= Update;
     }
   } else {
     // If an update was already in progress, we should schedule an Update
     // effect even though we're bailing out, so that cWU/cDU are called.
     if (typeof instance.componentDidMount === 'function') {
-      if (
-        __DEV__ &&
-        enableDoubleInvokingEffects &&
-        (workInProgress.mode & (BlockingMode | ConcurrentMode)) !== NoMode
-      ) {
-        workInProgress.flags |= MountLayoutDev | Update;
-      } else {
-        workInProgress.flags |= Update;
-      }
+      workInProgress.flags |= Update;
     }
 
     // If shouldComponentUpdate returned false, we should still update the