forceUpdate

Adds a field to the update queue that causes shouldComponentUpdate to
be skipped.

src/renderers/shared/fiber/ReactFiberBeginWork.js

@@ -163,6 +163,12 @@ module.exports = function<T, P, I, C>(config : HostConfig<T, P, I, C>, getSchedu
       updateQueue.isReplace = true;
       scheduleUpdate(fiber, updateQueue, LowPriority);
     },
+    enqueueForceUpdate(instance) {
+      const fiber = ReactInstanceMap.get(instance);
+      const updateQueue = fiber.updateQueue || createUpdateQueue(null);
+      updateQueue.isForced = true;
+      scheduleUpdate(fiber, updateQueue, LowPriority);
+    },
     enqueueCallback(instance, callback) {
       const fiber = ReactInstanceMap.get(instance);
       let updateQueue = fiber.updateQueue ?
@@ -204,7 +210,8 @@ module.exports = function<T, P, I, C>(config : HostConfig<T, P, I, C>, getSchedu
       // The instance needs access to the fiber so that it can schedule updates
       ReactInstanceMap.set(instance, workInProgress);
       instance.updater = updater;
-    } else if (typeof instance.shouldComponentUpdate === 'function') {
+    } else if (typeof instance.shouldComponentUpdate === 'function' &&
+               !(updateQueue && updateQueue.isForced)) {
       if (workInProgress.memoizedProps !== null) {
         // Reset the props, in case this is a ping-pong case rather than a
         // completed update case. For the completed update case, the instance

src/renderers/shared/fiber/ReactFiberUpdateQueue.js

@@ -21,6 +21,7 @@ type UpdateQueueNode = {
 
 export type UpdateQueue = UpdateQueueNode & {
   isReplace: boolean,
+  isForced: boolean,
   tail: UpdateQueueNode
 };
 
@@ -31,6 +32,7 @@ exports.createUpdateQueue = function(partialState : mixed) : UpdateQueue {
     callbackWasCalled: false,
     next: null,
     isReplace: false,
+    isForced: false,
     tail: (null : any),
   };
   queue.tail = queue;

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

@@ -682,4 +682,44 @@ describe('ReactIncremental', () => {
     ReactNoop.flush();
     expect(instance.state).toEqual({ d: 'd' });
   });
+
+  it('can forceUpdate', () => {
+    const ops = [];
+
+    function Baz() {
+      ops.push('Baz');
+      return <div />;
+    }
+
+    let instance;
+    class Bar extends React.Component {
+      constructor() {
+        super();
+        instance = this;
+      }
+      shouldComponentUpdate() {
+        return false;
+      }
+      render() {
+        ops.push('Bar');
+        return <Baz />;
+      }
+    }
+
+    function Foo() {
+      ops.push('Foo');
+      return (
+        <div>
+          <Bar />
+        </div>
+      );
+    }
+
+    ReactNoop.render(<Foo />);
+    ReactNoop.flush();
+    expect(ops).toEqual(['Foo', 'Bar', 'Baz']);
+    instance.forceUpdate();
+    ReactNoop.flush();
+    expect(ops).toEqual(['Foo', 'Bar', 'Baz', 'Bar', 'Baz']);
+  });
 });