From eafe0e4277ad39b6f0d84cc1322058756494a0aa Mon Sep 17 00:00:00 2001
From: Sebastian Markbage <sema@fb.com>
Date: Fri, 9 Apr 2021 17:31:08 -0400
Subject: [PATCH] Merge isObject branches

We assume that isArray and getIteratorFn are only called on objects.

So we shouldn't have to check that again and again, and then check a flag.

We can just stay in this branch.

There is a slight semantic breakage here because you could have an
iterator on a function, such as if it's a generator function. But that's
not supported and that currently only works at the root. The inner slots
don't support this.

So this just makes it consistent.
---
 .../src/ReactChildFiber.new.js                | 46 +++++++++----------
 .../src/ReactChildFiber.old.js                | 46 +++++++++----------
 2 files changed, 42 insertions(+), 50 deletions(-)

diff --git a/packages/react-reconciler/src/ReactChildFiber.new.js b/packages/react-reconciler/src/ReactChildFiber.new.js
index e9fdf0b654b5a..024a903dbd915 100644
--- a/packages/react-reconciler/src/ReactChildFiber.new.js
+++ b/packages/react-reconciler/src/ReactChildFiber.new.js
@@ -1231,9 +1231,7 @@ function ChildReconciler(shouldTrackSideEffects) {
     }
 
     // Handle object types
-    const isObject = typeof newChild === 'object' && newChild !== null;
-
-    if (isObject) {
+    if (typeof newChild === 'object' && newChild !== null) {
       switch (newChild.$$typeof) {
         case REACT_ELEMENT_TYPE:
           return placeSingleChild(
@@ -1266,6 +1264,26 @@ function ChildReconciler(shouldTrackSideEffects) {
             );
           }
       }
+
+      if (isArray(newChild)) {
+        return reconcileChildrenArray(
+          returnFiber,
+          currentFirstChild,
+          newChild,
+          lanes,
+        );
+      }
+
+      if (getIteratorFn(newChild)) {
+        return reconcileChildrenIterator(
+          returnFiber,
+          currentFirstChild,
+          newChild,
+          lanes,
+        );
+      }
+
+      throwOnInvalidObjectType(returnFiber, newChild);
     }
 
     if (typeof newChild === 'string' || typeof newChild === 'number') {
@@ -1279,28 +1297,6 @@ function ChildReconciler(shouldTrackSideEffects) {
       );
     }
 
-    if (isArray(newChild)) {
-      return reconcileChildrenArray(
-        returnFiber,
-        currentFirstChild,
-        newChild,
-        lanes,
-      );
-    }
-
-    if (getIteratorFn(newChild)) {
-      return reconcileChildrenIterator(
-        returnFiber,
-        currentFirstChild,
-        newChild,
-        lanes,
-      );
-    }
-
-    if (isObject) {
-      throwOnInvalidObjectType(returnFiber, newChild);
-    }
-
     if (__DEV__) {
       if (typeof newChild === 'function') {
         warnOnFunctionType(returnFiber);
diff --git a/packages/react-reconciler/src/ReactChildFiber.old.js b/packages/react-reconciler/src/ReactChildFiber.old.js
index 34120a641ba3b..80b4fc35512d0 100644
--- a/packages/react-reconciler/src/ReactChildFiber.old.js
+++ b/packages/react-reconciler/src/ReactChildFiber.old.js
@@ -1231,9 +1231,7 @@ function ChildReconciler(shouldTrackSideEffects) {
     }
 
     // Handle object types
-    const isObject = typeof newChild === 'object' && newChild !== null;
-
-    if (isObject) {
+    if (typeof newChild === 'object' && newChild !== null) {
       switch (newChild.$$typeof) {
         case REACT_ELEMENT_TYPE:
           return placeSingleChild(
@@ -1266,6 +1264,26 @@ function ChildReconciler(shouldTrackSideEffects) {
             );
           }
       }
+
+      if (isArray(newChild)) {
+        return reconcileChildrenArray(
+          returnFiber,
+          currentFirstChild,
+          newChild,
+          lanes,
+        );
+      }
+
+      if (getIteratorFn(newChild)) {
+        return reconcileChildrenIterator(
+          returnFiber,
+          currentFirstChild,
+          newChild,
+          lanes,
+        );
+      }
+
+      throwOnInvalidObjectType(returnFiber, newChild);
     }
 
     if (typeof newChild === 'string' || typeof newChild === 'number') {
@@ -1279,28 +1297,6 @@ function ChildReconciler(shouldTrackSideEffects) {
       );
     }
 
-    if (isArray(newChild)) {
-      return reconcileChildrenArray(
-        returnFiber,
-        currentFirstChild,
-        newChild,
-        lanes,
-      );
-    }
-
-    if (getIteratorFn(newChild)) {
-      return reconcileChildrenIterator(
-        returnFiber,
-        currentFirstChild,
-        newChild,
-        lanes,
-      );
-    }
-
-    if (isObject) {
-      throwOnInvalidObjectType(returnFiber, newChild);
-    }
-
     if (__DEV__) {
       if (typeof newChild === 'function') {
         warnOnFunctionType(returnFiber);