Clean up

Use a union type for the head of StateQueue.

src/renderers/shared/fiber/ReactFiberBeginWork.js

@@ -119,20 +119,18 @@ module.exports = function<T, P, I, C>(config : HostConfig<T, P, I, C>, getSchedu
     fiber.stateQueue = stateQueue;
     // Schedule update on the alternate as well, since we don't know which tree
     // is current.
-    // $FlowFixMe: Intersection issue. Don't know why it's only happening here.
-    const { alternate } = fiber;
-    if (alternate !== null) {
-      alternate.stateQueue = stateQueue;
+    if (fiber.alternate !== null) {
+      fiber.alternate.stateQueue = stateQueue;
     }
     while (true) {
       if (fiber.pendingWorkPriority === NoWork ||
           fiber.pendingWorkPriority >= priorityLevel) {
         fiber.pendingWorkPriority = priorityLevel;
       }
-      if (alternate !== null) {
-        if (alternate.pendingWorkPriority === NoWork ||
-            alternate.pendingWorkPriority >= priorityLevel) {
-          alternate.pendingWorkPriority = priorityLevel;
+      if (fiber.alternate !== null) {
+        if (fiber.alternate.pendingWorkPriority === NoWork ||
+            fiber.alternate.pendingWorkPriority >= priorityLevel) {
+          fiber.alternate.pendingWorkPriority = priorityLevel;
         }
       }
       // Duck type root
@@ -169,12 +167,9 @@ module.exports = function<T, P, I, C>(config : HostConfig<T, P, I, C>, getSchedu
     }
     // Compute the state using the memoized state and the pending state queue.
     var stateQueue = workInProgress.stateQueue;
-    var state;
-    if (!current) {
-      state = mergeStateQueue(null, props, stateQueue);
-    } else {
-      state = mergeStateQueue(current.memoizedState, props, stateQueue);
-    }
+    var state = current ?
+       mergeStateQueue(stateQueue, current.memoizedState, props) :
+       mergeStateQueue(stateQueue, null, props);
 
     var instance = workInProgress.stateNode;
     if (!instance) {

src/renderers/shared/fiber/ReactFiberStateQueue.js

@@ -12,23 +12,32 @@
 
 'use strict';
 
-export type StateQueue = {
+type StateQueueNode = {
   partialState: any,
-  next: StateQueue | null,
-  tail: StateQueue | null
+  callback: ?Function,
+  next: ?StateQueueNode,
+};
+
+export type StateQueue = StateQueueNode & {
+  tail: ?StateQueueNode
 };
 
 exports.createStateQueue = function(partialState : mixed) : StateQueue {
   return {
     partialState,
+    callback: null,
     next: null,
     tail: null,
   };
 };
 
-exports.addToQueue = function(queue : StateQueue, partialState : mixed): StateQueue {
-  const node = exports.createStateQueue(partialState);
-  if (queue.tail === null) {
+exports.addToQueue = function(queue : StateQueue, partialState : mixed) : StateQueue {
+  const node = {
+    partialState,
+    callback: null,
+    next: null,
+  };
+  if (!queue.tail) {
     queue.next = node;
   } else {
     queue.tail.next = node;
@@ -37,16 +46,17 @@ exports.addToQueue = function(queue : StateQueue, partialState : mixed): StateQu
   return queue;
 };
 
-exports.mergeStateQueue = function(prevState : any, props : any, queue : ?StateQueue) : any {
-  if (!queue) {
+exports.mergeStateQueue = function(queue : ?StateQueue, prevState : any, props : any) : any {
+  let node : ?StateQueueNode = queue;
+  if (!node) {
     return prevState;
   }
   let state = Object.assign({}, prevState);
   do {
-    const partialState = typeof queue.partialState === 'function' ?
-      queue.partialState(state, props) :
-      queue.partialState;
+    const partialState = typeof node.partialState === 'function' ?
+      node.partialState(state, props) :
+      node.partialState;
     state = Object.assign(state, partialState);
-  } while (queue = queue.next);
+  } while (node = node.next);
   return state;
 };

src/renderers/shared/fiber/__tests__/ReactIncremental-test.js

@@ -648,8 +648,8 @@ describe('ReactIncremental', () => {
     instance.setState(updater);
     ReactNoop.flush();
     expect(instance.state.num).toEqual(2);
-    ReactNoop.render(<Foo multiplier={3} />);
     instance.setState(updater);
+    ReactNoop.render(<Foo multiplier={3} />);
     ReactNoop.flush();
     expect(instance.state.num).toEqual(6);
   });