Delete remaining references to effect list

I think that's it!

.eslintrc.js

@@ -116,7 +116,7 @@ module.exports = {
     'react-internal/no-cross-fork-types': [
       ERROR,
       {
-        old: [],
+        old: ['firstEffect', 'nextEffect'],
         new: [],
       },
     ],

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

@@ -263,20 +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;
-
     const deletions = returnFiber.deletions;
     if (deletions === null) {
       returnFiber.deletions = [childToDelete];

packages/react-reconciler/src/ReactFiber.new.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-    // The effect list is no longer valid.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+    // The effects are no longer valid.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-  // The effect list is no longer valid.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+  // The effects are no longer valid.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.new.js

@@ -2198,8 +2198,6 @@ function updateSuspensePrimaryChildren(
   primaryChildFragment.sibling = null;
   if (currentFallbackChildFragment !== null) {
     // Delete the fallback child fragment
-    currentFallbackChildFragment.nextEffect = null;
-    workInProgress.firstEffect = workInProgress.lastEffect = currentFallbackChildFragment;
     const deletions = workInProgress.deletions;
     if (deletions === null) {
       workInProgress.deletions = [currentFallbackChildFragment];
@@ -2261,22 +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(
@@ -2773,7 +2758,6 @@ function initSuspenseListRenderState(
   tail: null | Fiber,
   lastContentRow: null | Fiber,
   tailMode: SuspenseListTailMode,
-  lastEffectBeforeRendering: null | Fiber,
 ): void {
   const renderState: null | SuspenseListRenderState =
     workInProgress.memoizedState;
@@ -2785,7 +2769,6 @@ function initSuspenseListRenderState(
       last: lastContentRow,
       tail: tail,
       tailMode: tailMode,
-      lastEffect: lastEffectBeforeRendering,
     }: SuspenseListRenderState);
   } else {
     // We can reuse the existing object from previous renders.
@@ -2795,7 +2778,6 @@ function initSuspenseListRenderState(
     renderState.last = lastContentRow;
     renderState.tail = tail;
     renderState.tailMode = tailMode;
-    renderState.lastEffect = lastEffectBeforeRendering;
   }
 }
 
@@ -2877,7 +2859,6 @@ function updateSuspenseListComponent(
           tail,
           lastContentRow,
           tailMode,
-          workInProgress.lastEffect,
         );
         break;
       }
@@ -2909,7 +2890,6 @@ function updateSuspenseListComponent(
           tail,
           null, // last
           tailMode,
-          workInProgress.lastEffect,
         );
         break;
       }
@@ -2920,7 +2900,6 @@ function updateSuspenseListComponent(
           null, // tail
           null, // last
           undefined,
-          workInProgress.lastEffect,
         );
         break;
       }
@@ -3180,15 +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;
-
     const deletions = returnFiber.deletions;
     if (deletions === null) {
       returnFiber.deletions = [current];

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

@@ -1213,9 +1213,6 @@ export function detachFiberAfterEffects(fiber: Fiber): void {
   fiber.sibling = null;
   fiber.stateNode = null;
   fiber.updateQueue = null;
-  fiber.nextEffect = null;
-  fiber.firstEffect = null;
-  fiber.lastEffect = null;
 
   if (__DEV__) {
     fiber._debugOwner = null;

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

@@ -72,7 +72,9 @@ import {
   NoFlags,
   DidCapture,
   Snapshot,
+  ChildDeletion,
   StaticMask,
+  MutationMask,
 } from './ReactFiberFlags';
 import invariant from 'shared/invariant';
 
@@ -173,6 +175,31 @@ function markRef(workInProgress: Fiber) {
   workInProgress.flags |= Ref;
 }
 
+function hadNoMutationsEffects(current: null | Fiber, completedWork: Fiber) {
+  const didBailout = current !== null && current.child === completedWork.child;
+  if (didBailout) {
+    return true;
+  }
+
+  if ((completedWork.flags & ChildDeletion) !== NoFlags) {
+    return false;
+  }
+
+  // TODO: If we move the `hadNoMutationsEffects` call after `bubbleProperties`
+  // then we only have to check the `completedWork.subtreeFlags`.
+  let child = completedWork.child;
+  while (child !== null) {
+    if (
+      (child.flags & MutationMask) !== NoFlags ||
+      (child.subtreeFlags & MutationMask) !== NoFlags
+    ) {
+      return false;
+    }
+    child = child.sibling;
+  }
+  return true;
+}
+
 let appendAllChildren;
 let updateHostContainer;
 let updateHostComponent;
@@ -217,7 +244,7 @@ if (supportsMutation) {
     }
   };
 
-  updateHostContainer = function(workInProgress: Fiber) {
+  updateHostContainer = function(current: null | Fiber, workInProgress: Fiber) {
     // Noop
   };
   updateHostComponent = function(
@@ -461,13 +488,13 @@ if (supportsMutation) {
       node = node.sibling;
     }
   };
-  updateHostContainer = function(workInProgress: Fiber) {
+  updateHostContainer = function(current: null | Fiber, workInProgress: Fiber) {
     const portalOrRoot: {
       containerInfo: Container,
       pendingChildren: ChildSet,
       ...
     } = workInProgress.stateNode;
-    const childrenUnchanged = workInProgress.firstEffect === null;
+    const childrenUnchanged = hadNoMutationsEffects(current, workInProgress);
     if (childrenUnchanged) {
       // No changes, just reuse the existing instance.
     } else {
@@ -492,7 +519,7 @@ if (supportsMutation) {
     const oldProps = current.memoizedProps;
     // If there are no effects associated with this node, then none of our children had any updates.
     // This guarantees that we can reuse all of them.
-    const childrenUnchanged = workInProgress.firstEffect === null;
+    const childrenUnchanged = hadNoMutationsEffects(current, workInProgress);
     if (childrenUnchanged && oldProps === newProps) {
       // No changes, just reuse the existing instance.
       // Note that this might release a previous clone.
@@ -575,7 +602,7 @@ if (supportsMutation) {
   };
 } else {
   // No host operations
-  updateHostContainer = function(workInProgress: Fiber) {
+  updateHostContainer = function(current: null | Fiber, workInProgress: Fiber) {
     // Noop
   };
   updateHostComponent = function(
@@ -847,7 +874,7 @@ function completeWork(
           workInProgress.flags |= Snapshot;
         }
       }
-      updateHostContainer(workInProgress);
+      updateHostContainer(current, workInProgress);
       bubbleProperties(workInProgress);
       return null;
     }
@@ -1142,7 +1169,7 @@ function completeWork(
     }
     case HostPortal:
       popHostContainer(workInProgress);
-      updateHostContainer(workInProgress);
+      updateHostContainer(current, workInProgress);
       if (current === null) {
         preparePortalMount(workInProgress.stateNode.containerInfo);
       }
@@ -1226,11 +1253,7 @@ function completeWork(
 
                 // Rerender the whole list, but this time, we'll force fallbacks
                 // to stay in place.
-                // Reset the effect list before doing the second pass since that's now invalid.
-                if (renderState.lastEffect === null) {
-                  workInProgress.firstEffect = null;
-                }
-                workInProgress.lastEffect = renderState.lastEffect;
+                // Reset the effect flags before doing the second pass since that's now invalid.
                 // Reset the child fibers to their original state.
                 workInProgress.subtreeFlags = NoFlags;
                 resetChildFibers(workInProgress, renderLanes);
@@ -1301,15 +1324,6 @@ function completeWork(
               !renderedTail.alternate &&
               !getIsHydrating() // We don't cut it if we're hydrating.
             ) {
-              // We need to delete the row we just rendered.
-              // Reset the effect list to what it was before we rendered this
-              // child. The nested children have already appended themselves.
-              const lastEffect = (workInProgress.lastEffect =
-                renderState.lastEffect);
-              // Remove any effects that were appended after this point.
-              if (lastEffect !== null) {
-                lastEffect.nextEffect = null;
-              }
               // We're done.
               bubbleProperties(workInProgress);
               return null;
@@ -1369,7 +1383,6 @@ function completeWork(
         const next = renderState.tail;
         renderState.rendering = next;
         renderState.tail = next.sibling;
-        renderState.lastEffect = workInProgress.lastEffect;
         renderState.renderingStartTime = now();
         next.sibling = null;
 

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

@@ -125,18 +125,6 @@ function deleteHydratableInstance(
   childToDelete.stateNode = instance;
   childToDelete.return = returnFiber;
 
-  // This might seem like it belongs on progressedFirstDeletion. However,
-  // these children are not part of the reconciliation list of children.
-  // Even if we abort and rereconcile the children, that will try to hydrate
-  // again and the nodes are still in the host tree so these will be
-  // recreated.
-  if (returnFiber.lastEffect !== null) {
-    returnFiber.lastEffect.nextEffect = childToDelete;
-    returnFiber.lastEffect = childToDelete;
-  } else {
-    returnFiber.firstEffect = returnFiber.lastEffect = childToDelete;
-  }
-
   const deletions = returnFiber.deletions;
   if (deletions === null) {
     returnFiber.deletions = [childToDelete];

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

@@ -60,9 +60,6 @@ export type SuspenseListRenderState = {|
   tail: null | Fiber,
   // Tail insertions setting.
   tailMode: SuspenseListTailMode,
-  // Last Effect before we rendered the "rendering" item.
-  // Used to remove new effects added by the rendered item.
-  lastEffect: null | Fiber,
 |};
 
 export function shouldCaptureSuspense(

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

@@ -188,8 +188,6 @@ function throwException(
 ) {
   // The source fiber did not complete.
   sourceFiber.flags |= Incomplete;
-  // Its effect list is no longer valid.
-  sourceFiber.firstEffect = sourceFiber.lastEffect = null;
 
   if (
     value !== null &&