Fabric: Additional static asserts in Differentiator

Summary: I am about to change the definition of ShadowView a bit, so I think we need to ensure that we don't regress move semantic.

Reviewed By: JoshuaGross, sammy-SC

Differential Revision: D15911453

fbshipit-source-id: ce2cd4cb2375ecb76295948a1e9b5d2e7fb80f38

Author: shergin

ReactCommon/fabric/mounting/Differentiator.cpp

@@ -115,6 +115,29 @@ static ShadowViewNodePair::List sliceChildShadowNodeViewPairs(
   return pairList;
 }
 
+/*
+ * Before we start to diff, let's make sure all our core data structures are in
+ * good shape to deliver the best performance.
+ */
+static_assert(
+    std::is_move_constructible<ShadowViewMutation>::value,
+    "`ShadowViewMutation` must be `move constructible`.");
+static_assert(
+    std::is_move_constructible<ShadowView>::value,
+    "`ShadowView` must be `move constructible`.");
+static_assert(
+    std::is_move_constructible<ShadowViewNodePair>::value,
+    "`ShadowViewNodePair` must be `move constructible`.");
+static_assert(
+    std::is_move_assignable<ShadowViewMutation>::value,
+    "`ShadowViewMutation` must be `move assignable`.");
+static_assert(
+    std::is_move_assignable<ShadowView>::value,
+    "`ShadowView` must be `move assignable`.");
+static_assert(
+    std::is_move_assignable<ShadowViewNodePair>::value,
+    "`ShadowViewNodePair` must be `move assignable`.");
+
 static void calculateShadowViewMutations(
     ShadowViewMutation::List &mutations,
     ShadowView const &parentShadowView,
@@ -183,7 +206,7 @@ static void calculateShadowViewMutations(
     auto const &newChildPair = newChildPairs[index];
 
     insertMutations.push_back(ShadowViewMutation::InsertMutation(
-          parentShadowView, newChildPair.shadowView, index));
+        parentShadowView, newChildPair.shadowView, index));
 
     insertedPairs.insert({newChildPair.shadowView.tag, &newChildPair});
   }