Run yarn replace-fork

Replaces the old fork with the new fork. The two implementations are
now identical.

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

@@ -13,12 +13,7 @@ import type {Fiber} from './ReactInternalTypes';
 import type {Lanes} from './ReactFiberLane.old';
 
 import getComponentName from 'shared/getComponentName';
-import {
-  Deletion,
-  ChildDeletion,
-  Placement,
-  StaticMask,
-} from './ReactFiberFlags';
+import {Placement, ChildDeletion} from './ReactFiberFlags';
 import {
   getIteratorFn,
   REACT_ELEMENT_TYPE,
@@ -268,21 +263,6 @@ function ChildReconciler(shouldTrackSideEffects) {
       // Noop.
       return;
     }
-    // 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 {
-      returnFiber.firstEffect = returnFiber.lastEffect = childToDelete;
-    }
-    childToDelete.nextEffect = null;
-    childToDelete.flags = (childToDelete.flags & StaticMask) | Deletion;
-
     const deletions = returnFiber.deletions;
     if (deletions === null) {
       returnFiber.deletions = [childToDelete];

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

@@ -144,10 +144,6 @@ function FiberNode(
 
   // Effects
   this.flags = NoFlags;
-  this.nextEffect = null;
-
-  this.firstEffect = null;
-  this.lastEffect = null;
   this.subtreeFlags = NoFlags;
   this.deletions = null;
 
@@ -285,10 +281,7 @@ export function createWorkInProgress(current: Fiber, pendingProps: any): Fiber {
     // Reset the effect tag.
     workInProgress.flags = NoFlags;
 
-    // The effect list is no longer valid.
-    workInProgress.nextEffect = null;
-    workInProgress.firstEffect = null;
-    workInProgress.lastEffect = null;
+    // The effects are no longer valid.
     workInProgress.subtreeFlags = NoFlags;
     workInProgress.deletions = null;
 
@@ -370,10 +363,7 @@ export function resetWorkInProgress(workInProgress: Fiber, renderLanes: Lanes) {
   // that child fiber is setting, not the reconciliation.
   workInProgress.flags &= StaticMask | Placement;
 
-  // The effect list is no longer valid.
-  workInProgress.nextEffect = null;
-  workInProgress.firstEffect = null;
-  workInProgress.lastEffect = null;
+  // The effects are no longer valid.
 
   const current = workInProgress.alternate;
   if (current === null) {
@@ -403,6 +393,9 @@ export function resetWorkInProgress(workInProgress: Fiber, renderLanes: Lanes) {
     workInProgress.lanes = current.lanes;
 
     workInProgress.child = current.child;
+    // TODO: `subtreeFlags` should be reset to NoFlags, like we do in
+    // `createWorkInProgress`. Nothing reads this until the complete phase,
+    // currently, but it might in the future, and we should be consistent.
     workInProgress.subtreeFlags = current.subtreeFlags;
     workInProgress.deletions = null;
     workInProgress.memoizedProps = current.memoizedProps;
@@ -847,9 +840,6 @@ export function assignFiberPropertiesInDEV(
   target.dependencies = source.dependencies;
   target.mode = source.mode;
   target.flags = source.flags;
-  target.nextEffect = source.nextEffect;
-  target.firstEffect = source.firstEffect;
-  target.lastEffect = source.lastEffect;
   target.subtreeFlags = source.subtreeFlags;
   target.deletions = source.deletions;
   target.lanes = source.lanes;

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

@@ -67,7 +67,6 @@ import {
   DidCapture,
   Update,
   Ref,
-  Deletion,
   ChildDeletion,
   ForceUpdateForLegacySuspense,
   StaticMask,
@@ -2199,10 +2198,6 @@ function updateSuspensePrimaryChildren(
   primaryChildFragment.sibling = null;
   if (currentFallbackChildFragment !== null) {
     // Delete the fallback child fragment
-    currentFallbackChildFragment.nextEffect = null;
-    currentFallbackChildFragment.flags =
-      (currentFallbackChildFragment.flags & StaticMask) | Deletion;
-    workInProgress.firstEffect = workInProgress.lastEffect = currentFallbackChildFragment;
     const deletions = workInProgress.deletions;
     if (deletions === null) {
       workInProgress.deletions = [currentFallbackChildFragment];
@@ -2264,22 +2259,9 @@ function updateSuspenseFallbackChildren(
         currentPrimaryChildFragment.treeBaseDuration;
     }
 
-    if (currentFallbackChildFragment !== null) {
-      // 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. So we need to remove it from the list.
-      // Deletions are stored on the same list as effects, and are always added
-      // to the front. So we know that the first effect must be the fallback
-      // deletion effect, and everything after that is from the primary free.
-      const firstPrimaryTreeEffect = currentFallbackChildFragment.nextEffect;
-      if (firstPrimaryTreeEffect !== null) {
-        workInProgress.firstEffect = firstPrimaryTreeEffect;
-      } else {
-        // TODO: Reset this somewhere else? Lol legacy mode is so weird.
-        workInProgress.firstEffect = workInProgress.lastEffect = null;
-      }
-    }
-
+    // The fallback fiber was added as a deletion during the first pass.
+    // However, since we're going to remain on the fallback, we no longer want
+    // to delete it.
     workInProgress.deletions = null;
   } else {
     primaryChildFragment = createWorkInProgressOffscreenFiber(
@@ -2776,7 +2758,6 @@ function initSuspenseListRenderState(
   tail: null | Fiber,
   lastContentRow: null | Fiber,
   tailMode: SuspenseListTailMode,
-  lastEffectBeforeRendering: null | Fiber,
 ): void {
   const renderState: null | SuspenseListRenderState =
     workInProgress.memoizedState;
@@ -2788,7 +2769,6 @@ function initSuspenseListRenderState(
       last: lastContentRow,
       tail: tail,
       tailMode: tailMode,
-      lastEffect: lastEffectBeforeRendering,
     }: SuspenseListRenderState);
   } else {
     // We can reuse the existing object from previous renders.
@@ -2798,7 +2778,6 @@ function initSuspenseListRenderState(
     renderState.last = lastContentRow;
     renderState.tail = tail;
     renderState.tailMode = tailMode;
-    renderState.lastEffect = lastEffectBeforeRendering;
   }
 }
 
@@ -2880,7 +2859,6 @@ function updateSuspenseListComponent(
           tail,
           lastContentRow,
           tailMode,
-          workInProgress.lastEffect,
         );
         break;
       }
@@ -2912,7 +2890,6 @@ function updateSuspenseListComponent(
           tail,
           null, // last
           tailMode,
-          workInProgress.lastEffect,
         );
         break;
       }
@@ -2923,7 +2900,6 @@ function updateSuspenseListComponent(
           null, // tail
           null, // last
           undefined,
-          workInProgress.lastEffect,
         );
         break;
       }
@@ -3183,16 +3159,6 @@ function remountFiber(
 
     // Delete the old fiber and place the new one.
     // Since the old fiber is disconnected, we have to schedule it manually.
-    const last = returnFiber.lastEffect;
-    if (last !== null) {
-      last.nextEffect = current;
-      returnFiber.lastEffect = current;
-    } else {
-      returnFiber.firstEffect = returnFiber.lastEffect = current;
-    }
-    current.nextEffect = null;
-    current.flags = (current.flags & StaticMask) | Deletion;
-
     const deletions = returnFiber.deletions;
     if (deletions === null) {
       returnFiber.deletions = [current];