Fabric: Getting rid of many `auto &&`

Summary:
@public
After reading about move-semantic and rvalue refs I realized that we (I) definitely overuse  `auto &&` (aka universal reference) construction. Even if this is harmless, does not look good and idiomatic.
Whenever I used that from a semantical point of view I always meant  "I need an alias for this" which is actually "read-only reference" which is `const auto &`.
This is also fit good to our policy where "everything is const (immutable) by default".
Hence I change that to how it should be.

Reviewed By: fkgozali

Differential Revision: D8475637

fbshipit-source-id: 0a691ededa0e798db8ffa053bff0f400913ab7b8

React/Fabric/Mounting/ComponentViews/ActivityIndicator/RCTActivityIndicatorViewComponentView.mm

@@ -30,7 +30,7 @@ static UIActivityIndicatorViewStyle convertActivityIndicatorViewStyle(const Acti
     _activityIndicatorView = [[UIActivityIndicatorView alloc] initWithFrame:self.bounds];
     _activityIndicatorView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
 
-    auto &&defaultProps = ActivityIndicatorViewProps();
+    const auto &defaultProps = ActivityIndicatorViewProps();
 
     if (defaultProps.animating) {
       [_activityIndicatorView startAnimating];

React/Fabric/Mounting/ComponentViews/Switch/RCTSwitchComponentView.mm

@@ -26,7 +26,7 @@ using namespace facebook::react;
                  action:@selector(onChange:)
        forControlEvents:UIControlEventValueChanged];
 
-    auto &&defaultProps = SwitchProps();
+    const auto &defaultProps = SwitchProps();
 
     _switchView.on = defaultProps.value;
 

React/Fabric/RCTSurfaceTouchHandler.mm

@@ -191,7 +191,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithTarget:(id)target action:(SEL)action
 - (void)_registerTouches:(NSSet<UITouch *> *)touches
 {
   for (UITouch *touch in touches) {
-    auto &&activeTouch = CreateTouchWithUITouch(touch, _rootComponentView);
+    auto activeTouch = CreateTouchWithUITouch(touch, _rootComponentView);
     activeTouch.touch.identifier = _identifierPool.dequeue();
     _activeTouches.emplace(touch, activeTouch);
   }
@@ -207,7 +207,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithTarget:(id)target action:(SEL)action
 - (void)_unregisterTouches:(NSSet<UITouch *> *)touches
 {
   for (UITouch *touch in touches) {
-    auto &&activeTouch = _activeTouches[touch];
+    const auto &activeTouch = _activeTouches[touch];
     _identifierPool.enqueue(activeTouch.touch.identifier);
     _activeTouches.erase(touch);
   }
@@ -221,7 +221,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithTarget:(id)target action:(SEL)action
   BOOL isEndishEventType = eventType == RCTTouchEventTypeTouchEnd || eventType == RCTTouchEventTypeTouchCancel;
 
   for (UITouch *touch in touches) {
-    auto &&activeTouch = _activeTouches[touch];
+    const auto &activeTouch = _activeTouches[touch];
 
     if (!activeTouch.eventEmitter) {
       continue;
@@ -232,7 +232,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithTarget:(id)target action:(SEL)action
     uniqueEventEmitter.insert(activeTouch.eventEmitter);
   }
 
-  for (auto &&pair : _activeTouches) {
+  for (const auto &pair : _activeTouches) {
     if (!pair.second.eventEmitter) {
       continue;
     }
@@ -247,10 +247,10 @@ RCT_NOT_IMPLEMENTED(- (instancetype)initWithTarget:(id)target action:(SEL)action
     event.touches.insert(pair.second.touch);
   }
 
-  for (auto &&eventEmitter : uniqueEventEmitter) {
+  for (const auto &eventEmitter : uniqueEventEmitter) {
     event.targetTouches.clear();
 
-    for (auto &&pair : _activeTouches) {
+    for (const auto &pair : _activeTouches) {
       if (pair.second.eventEmitter == eventEmitter) {
         event.targetTouches.insert(pair.second.touch);
       }

ReactCommon/fabric/core/componentdescriptor/ConcreteComponentDescriptor.h

@@ -64,7 +64,7 @@ public:
     assert(std::dynamic_pointer_cast<const ConcreteProps>(props));
     assert(std::dynamic_pointer_cast<const ConcreteEventEmitter>(eventEmitter));
 
-    auto &&shadowNode = std::make_shared<ShadowNodeT>(
+    const auto &shadowNode = std::make_shared<ShadowNodeT>(
       tag,
       rootTag,
       std::static_pointer_cast<const ConcreteProps>(props),
@@ -85,7 +85,7 @@ public:
   ) const override {
     assert(std::dynamic_pointer_cast<const ShadowNodeT>(sourceShadowNode));
 
-    auto &&shadowNode = std::make_shared<ShadowNodeT>(
+    const auto &shadowNode = std::make_shared<ShadowNodeT>(
       std::static_pointer_cast<const ShadowNodeT>(sourceShadowNode),
       std::static_pointer_cast<const ConcreteProps>(props),
       std::static_pointer_cast<const ConcreteEventEmitter>(eventEmitter),

ReactCommon/fabric/core/events/EventEmitter.cpp

@@ -33,7 +33,7 @@ void EventEmitter::dispatchEvent(
   const folly::dynamic &payload,
   const EventPriority &priority
 ) const {
-  auto &&eventDispatcher = eventDispatcher_.lock();
+  const auto &eventDispatcher = eventDispatcher_.lock();
   if (!eventDispatcher) {
     return;
   }
@@ -50,7 +50,7 @@ void EventEmitter::dispatchEvent(
 }
 
 EventTarget EventEmitter::createEventTarget() const {
-  auto &&eventDispatcher = eventDispatcher_.lock();
+  const auto &eventDispatcher = eventDispatcher_.lock();
   assert(eventDispatcher);
   return eventDispatcher->createEventTarget(instanceHandle_);
 }

ReactCommon/fabric/core/propsConversions.h

@@ -41,12 +41,12 @@ inline T convertRawProp(
   const T &sourceValue,
   const T &defaultValue = T()
 ) {
-  auto &&iterator = rawProps.find(name);
+  const auto &iterator = rawProps.find(name);
   if (iterator == rawProps.end()) {
     return sourceValue;
   }
 
-  auto &&value = iterator->second;
+  const auto &value = iterator->second;
 
   // Special case: `null` always means `the prop was removed, use default value`.
   if (value.isNull()) {
@@ -65,12 +65,12 @@ inline static folly::Optional<T> convertRawProp(
   const folly::Optional<T> &sourceValue,
   const folly::Optional<T> &defaultValue = {}
 ) {
-  auto &&iterator = rawProps.find(name);
+  const auto &iterator = rawProps.find(name);
   if (iterator == rawProps.end()) {
     return sourceValue;
   }
 
-  auto &&value = iterator->second;
+  const auto &value = iterator->second;
 
   // Special case: `null` always means `the prop was removed, use default value`.
   if (value.isNull()) {

ReactCommon/fabric/scrollview/ScrollViewShadowNode.cpp

@@ -22,11 +22,11 @@ void ScrollViewShadowNode::updateLocalData() {
   ensureUnsealed();
 
   Rect contentBoundingRect;
-  for (auto &&childNode : getLayoutableChildNodes()) {
+  for (const auto &childNode : getLayoutableChildNodes()) {
     contentBoundingRect.unionInPlace(childNode->getLayoutMetrics().frame);
   }
 
-  auto &&localData = std::make_shared<const ScrollViewLocalData>(contentBoundingRect);
+  const auto &localData = std::make_shared<const ScrollViewLocalData>(contentBoundingRect);
   setLocalData(localData);
 }
 

ReactCommon/fabric/text/basetext/BaseTextShadowNode.cpp

@@ -25,7 +25,7 @@ AttributedString BaseTextShadowNode::getAttributedString(
 
   AttributedString attributedString;
 
-  for (auto &&childNode : *childNodes) {
+  for (const auto &childNode : *childNodes) {
     // RawShadowNode
     SharedRawTextShadowNode rawTextShadowNode = std::dynamic_pointer_cast<const RawTextShadowNode>(childNode);
     if (rawTextShadowNode) {

ReactCommon/fabric/uimanager/Scheduler.cpp

@@ -24,8 +24,8 @@ namespace react {
 
 Scheduler::Scheduler(const SharedContextContainer &contextContainer):
   contextContainer_(contextContainer) {
-  auto &&eventDispatcher = std::make_shared<SchedulerEventDispatcher>();
-  auto &&componentDescriptorRegistry = ComponentDescriptorFactory::buildRegistry(eventDispatcher, contextContainer);
+  const auto &eventDispatcher = std::make_shared<SchedulerEventDispatcher>();
+  const auto &componentDescriptorRegistry = ComponentDescriptorFactory::buildRegistry(eventDispatcher, contextContainer);
 
   uiManager_ = std::make_shared<FabricUIManager>(componentDescriptorRegistry);
   uiManager_->setDelegate(this);
@@ -40,27 +40,27 @@ Scheduler::~Scheduler() {
 }
 
 void Scheduler::registerRootTag(Tag rootTag) {
-  auto &&shadowTree = std::make_shared<ShadowTree>(rootTag);
+  const auto &shadowTree = std::make_shared<ShadowTree>(rootTag);
   shadowTree->setDelegate(this);
   shadowTreeRegistry_.insert({rootTag, shadowTree});
 }
 
 void Scheduler::unregisterRootTag(Tag rootTag) {
-  auto &&iterator = shadowTreeRegistry_.find(rootTag);
-  auto &&shadowTree = iterator->second;
+  const auto &iterator = shadowTreeRegistry_.find(rootTag);
+  const auto &shadowTree = iterator->second;
   assert(shadowTree);
   shadowTree->setDelegate(nullptr);
   shadowTreeRegistry_.erase(iterator);
 }
 
 Size Scheduler::measure(const Tag &rootTag, const LayoutConstraints &layoutConstraints, const LayoutContext &layoutContext) const {
-  auto &&shadowTree = shadowTreeRegistry_.at(rootTag);
+  const auto &shadowTree = shadowTreeRegistry_.at(rootTag);
   assert(shadowTree);
   return shadowTree->measure(layoutConstraints, layoutContext);
 }
 
 void Scheduler::constraintLayout(const Tag &rootTag, const LayoutConstraints &layoutConstraints, const LayoutContext &layoutContext) {
-  auto &&shadowTree = shadowTreeRegistry_.at(rootTag);
+  const auto &shadowTree = shadowTreeRegistry_.at(rootTag);
   assert(shadowTree);
   return shadowTree->constraintLayout(layoutConstraints, layoutContext);
 }
@@ -86,8 +86,8 @@ void Scheduler::shadowTreeDidCommit(const SharedShadowTree &shadowTree, const Tr
 #pragma mark - UIManagerDelegate
 
 void Scheduler::uiManagerDidFinishTransaction(Tag rootTag, const SharedShadowNodeUnsharedList &rootChildNodes) {
-  auto &&iterator = shadowTreeRegistry_.find(rootTag);
-  auto &&shadowTree = iterator->second;
+  const auto &iterator = shadowTreeRegistry_.find(rootTag);
+  const auto &shadowTree = iterator->second;
   assert(shadowTree);
   return shadowTree->complete(rootChildNodes);
 }

ReactCommon/fabric/uimanager/ShadowTree.cpp

@@ -18,7 +18,7 @@ namespace react {
 ShadowTree::ShadowTree(Tag rootTag):
   rootTag_(rootTag) {
 
-  auto &&noopEventEmitter = std::make_shared<const ViewEventEmitter>(nullptr, rootTag, nullptr);
+  const auto &noopEventEmitter = std::make_shared<const ViewEventEmitter>(nullptr, rootTag, nullptr);
   rootShadowNode_ = std::make_shared<RootShadowNode>(
     rootTag,
     rootTag,
@@ -50,7 +50,7 @@ void ShadowTree::constraintLayout(const LayoutConstraints &layoutConstraints, co
 
 UnsharedRootShadowNode ShadowTree::cloneRootShadowNode(const LayoutConstraints &layoutConstraints, const LayoutContext &layoutContext) const {
   auto oldRootShadowNode = rootShadowNode_;
-  auto &&props = std::make_shared<const RootProps>(*oldRootShadowNode->getProps(), layoutConstraints, layoutContext);
+  const auto &props = std::make_shared<const RootProps>(*oldRootShadowNode->getProps(), layoutConstraints, layoutContext);
   auto newRootShadowNode = std::make_shared<RootShadowNode>(oldRootShadowNode, props, nullptr, nullptr);
   return newRootShadowNode;
 }
@@ -99,32 +99,32 @@ bool ShadowTree::commit(const SharedRootShadowNode &newRootShadowNode) {
 }
 
 void ShadowTree::emitLayoutEvents(const TreeMutationInstructionList &instructions) {
-  for (auto &&instruction : instructions) {
-    auto &&type = instruction.getType();
+  for (const auto &instruction : instructions) {
+    const auto &type = instruction.getType();
 
     // Only `Insertion` and `Replacement` instructions can affect layout metrics.
     if (
         type == TreeMutationInstruction::Insertion ||
         type == TreeMutationInstruction::Replacement
     ) {
-      auto &&newShadowNode = instruction.getNewChildNode();
-      auto &&eventEmitter = newShadowNode->getEventEmitter();
-      auto &&viewEventEmitter = std::dynamic_pointer_cast<const ViewEventEmitter>(eventEmitter);
+      const auto &newShadowNode = instruction.getNewChildNode();
+      const auto &eventEmitter = newShadowNode->getEventEmitter();
+      const auto &viewEventEmitter = std::dynamic_pointer_cast<const ViewEventEmitter>(eventEmitter);
 
       // Checking if particular shadow node supports `onLayout` event (part of `ViewEventEmitter`).
       if (viewEventEmitter) {
         // Now we know that both (old and new) shadow nodes must be `LayoutableShadowNode` subclasses.
         assert(std::dynamic_pointer_cast<const LayoutableShadowNode>(newShadowNode));
         // TODO(T29661055): Consider using `std::reinterpret_pointer_cast`.
-        auto &&newLayoutableShadowNode =
+        const auto &newLayoutableShadowNode =
           std::dynamic_pointer_cast<const LayoutableShadowNode>(newShadowNode);
 
         // In case if we have `oldShadowNode`, we have to check that layout metrics have changed.
         if (type == TreeMutationInstruction::Replacement) {
-          auto &&oldShadowNode = instruction.getOldChildNode();
+          const auto &oldShadowNode = instruction.getOldChildNode();
           assert(std::dynamic_pointer_cast<const LayoutableShadowNode>(oldShadowNode));
           // TODO(T29661055): Consider using `std::reinterpret_pointer_cast`.
-          auto &&oldLayoutableShadowNode =
+          const auto &oldLayoutableShadowNode =
             std::dynamic_pointer_cast<const LayoutableShadowNode>(oldShadowNode);
 
           if (oldLayoutableShadowNode->getLayoutMetrics() == newLayoutableShadowNode->getLayoutMetrics()) {

ReactCommon/fabric/view/ConcreteViewShadowNode.h

@@ -131,7 +131,7 @@ public:
       return false;
     }
 
-    auto &&other = static_cast<const ConcreteViewShadowNode&>(rhs);
+    const auto &other = static_cast<const ConcreteViewShadowNode&>(rhs);
     return getLayoutMetrics() == other.getLayoutMetrics();
   }
 

ReactCommon/fabric/view/ViewEventEmitter.cpp

@@ -28,7 +28,7 @@ void ViewEventEmitter::onAccessibilityMagicTap() const {
 
 void ViewEventEmitter::onLayout(const LayoutMetrics &layoutMetrics) const {
   folly::dynamic payload = folly::dynamic::object();
-  auto &&frame = layoutMetrics.frame;
+  const auto &frame = layoutMetrics.frame;
   payload["layout"] = folly::dynamic::object
     ("x", frame.origin.x)
     ("y", frame.origin.y)
@@ -57,7 +57,7 @@ static folly::dynamic touchPayload(const Touch &touch) {
 
 static folly::dynamic touchesPayload(const Touches &touches) {
   folly::dynamic array = folly::dynamic::array();
-  for (auto &&touch : touches) {
+  for (const auto &touch : touches) {
     array.push_back(touchPayload(touch));
   }
   return array;

ReactCommon/fabric/view/ViewProps.cpp

@@ -42,7 +42,7 @@ ViewProps::ViewProps(const ViewProps &sourceProps, const RawProps &rawProps):
 #pragma mark - DebugStringConvertible
 
 SharedDebugStringConvertibleList ViewProps::getDebugProps() const {
-  auto &&defaultViewProps = ViewProps();
+  const auto &defaultViewProps = ViewProps();
 
   return
     AccessibilityProps::getDebugProps() +

ReactCommon/fabric/view/conversions.h

@@ -230,11 +230,11 @@ inline void fromDynamic(const folly::dynamic &value, YGFloatOptional &result) {
 inline void fromDynamic(const folly::dynamic &value, Transform &result) {
   assert(value.isArray());
   Transform transformMatrix;
-  for (auto &&tranformConfiguration : value) {
+  for (const auto &tranformConfiguration : value) {
     assert(tranformConfiguration.isObject());
     auto pair = *tranformConfiguration.items().begin();
-    auto &&operation = pair.first.asString();
-    auto &&parameters = pair.second;
+    const auto &operation = pair.first.asString();
+    const auto &parameters = pair.second;
 
     if (operation == "matrix") {
       assert(parameters.isArray());