From dc12042589794b9bd4bbb4d477ca83576d83fe23 Mon Sep 17 00:00:00 2001
From: appleguy <scottgoodson@gmail.com>
Date: Sat, 9 Jul 2016 21:16:29 -0700
Subject: [PATCH] [ASDisplayNode] Do not start measurement for a transition if
 we have never been provided a constrainedSize. (#1844)

---
 AsyncDisplayKit/ASDisplayNode.mm | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/AsyncDisplayKit/ASDisplayNode.mm b/AsyncDisplayKit/ASDisplayNode.mm
index 2de5996f92..31c770cae6 100644
--- a/AsyncDisplayKit/ASDisplayNode.mm
+++ b/AsyncDisplayKit/ASDisplayNode.mm
@@ -695,6 +695,11 @@ static ASDisplayNodeMethodOverrides GetASDisplayNodeMethodOverrides(Class c)
                    shouldMeasureAsync:(BOOL)shouldMeasureAsync
                 measurementCompletion:(void(^)())completion
 {
+  if (_layout == nil) {
+    // constrainedSizeRange returns a struct and is invalid to call on nil.
+    // Defaulting to CGSizeZero can cause negative values in client layout code.
+    return;
+  }
   [self invalidateCalculatedLayout];
   [self transitionLayoutWithSizeRange:_layout.constrainedSizeRange
                              animated:animated