From 288a4c4d6db841da0afe99d057fddf151c339ddb Mon Sep 17 00:00:00 2001
From: Andrew Clark <acdlite@fb.com>
Date: Mon, 9 Jan 2017 17:14:09 -0800
Subject: [PATCH] Reset invalid UpdateQueue fields when cloning from current

Similar to what cloneFiber does. No change in behavior, but it's more
consistent this way.
---
 src/renderers/shared/fiber/ReactFiber.js      |  2 +-
 .../shared/fiber/ReactFiberUpdateQueue.js     | 26 +++++++++++--------
 2 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/src/renderers/shared/fiber/ReactFiber.js b/src/renderers/shared/fiber/ReactFiber.js
index 9cd295fc5c..d3f3a282d2 100644
--- a/src/renderers/shared/fiber/ReactFiber.js
+++ b/src/renderers/shared/fiber/ReactFiber.js
@@ -277,7 +277,7 @@ exports.cloneFiber = function(fiber : Fiber, priorityLevel : PriorityLevel) : Fi
   // pendingProps is here for symmetry but is unnecessary in practice for now.
   // TODO: Pass in the new pendingProps as an argument maybe?
   alt.pendingProps = fiber.pendingProps;
-  cloneUpdateQueue(alt, fiber);
+  cloneUpdateQueue(fiber, alt);
   alt.pendingWorkPriority = priorityLevel;
 
   alt.memoizedProps = fiber.memoizedProps;
diff --git a/src/renderers/shared/fiber/ReactFiberUpdateQueue.js b/src/renderers/shared/fiber/ReactFiberUpdateQueue.js
index e12ca91756..bb70bec77d 100644
--- a/src/renderers/shared/fiber/ReactFiberUpdateQueue.js
+++ b/src/renderers/shared/fiber/ReactFiberUpdateQueue.js
@@ -113,21 +113,25 @@ function ensureUpdateQueue(fiber : Fiber) : UpdateQueue {
 }
 
 // Clones an update queue from a source fiber onto its alternate.
-function cloneUpdateQueue(alt : Fiber, fiber : Fiber) : UpdateQueue | null {
-  const sourceQueue = fiber.updateQueue;
-  if (!sourceQueue) {
+function cloneUpdateQueue(current : Fiber, workInProgress : Fiber) : UpdateQueue | null {
+  const currentQueue = current.updateQueue;
+  if (!currentQueue) {
     // The source fiber does not have an update queue.
-    alt.updateQueue = null;
+    workInProgress.updateQueue = null;
     return null;
   }
   // If the alternate already has a queue, reuse the previous object.
-  const altQueue = alt.updateQueue || {};
-  altQueue.first = sourceQueue.first;
-  altQueue.last = sourceQueue.last;
-  altQueue.hasForceUpdate = sourceQueue.hasForceUpdate;
-  altQueue.callbackList = sourceQueue.callbackList;
-  altQueue.isProcessing = sourceQueue.isProcessing;
-  alt.updateQueue = altQueue;
+  const altQueue = workInProgress.updateQueue || {};
+  altQueue.first = currentQueue.first;
+  altQueue.last = currentQueue.last;
+
+  // These fields are invalid by the time we clone from current. Reset them.
+  altQueue.hasForceUpdate = false;
+  altQueue.callbackList = null;
+  altQueue.isProcessing = false;
+
+  workInProgress.updateQueue = altQueue;
+
   return altQueue;
 }
 exports.cloneUpdateQueue = cloneUpdateQueue;