From a2a84532ffb0ba759269f7bf331ec7e5e8b38a27 Mon Sep 17 00:00:00 2001
From: Emil Sjolander <emilsj@fb.com>
Date: Tue, 24 Jan 2017 17:04:54 -0800
Subject: [PATCH] Dont constrain absolute children to zero sized parents

Summary: Absolute children should not be constraint to the size of their parent if the parent does not have a size as this was causes the layout of the child to be skipped.

Reviewed By: gkassabli

Differential Revision: D4453612

fbshipit-source-id: e8269521560d2f42b2d6f0f0ff264a1605a57d79
---
 tests/YGMeasureTest.cpp | 21 +++++++++++++++++++++
 yoga/Yoga.c             |  9 ++++-----
 2 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/tests/YGMeasureTest.cpp b/tests/YGMeasureTest.cpp
index 911f0c51..1e4ad175 100644
--- a/tests/YGMeasureTest.cpp
+++ b/tests/YGMeasureTest.cpp
@@ -47,6 +47,27 @@ TEST(YogaTest, dont_measure_single_grow_shrink_child) {
   YGNodeFreeRecursive(root);
 }
 
+TEST(YogaTest, measure_absolute_child_with_no_constraints) {
+  const YGNodeRef root = YGNodeNew();
+
+  const YGNodeRef root_child0 = YGNodeNew();
+  YGNodeInsertChild(root, root_child0, 0);
+
+  int measureCount = 0;
+
+  const YGNodeRef root_child0_child0 = YGNodeNew();
+  YGNodeStyleSetPositionType(root_child0_child0, YGPositionTypeAbsolute);
+  YGNodeSetContext(root_child0_child0, &measureCount);
+  YGNodeSetMeasureFunc(root_child0_child0, _measure);
+  YGNodeInsertChild(root_child0, root_child0_child0, 0);
+
+  YGNodeCalculateLayout(root, YGUndefined, YGUndefined, YGDirectionLTR);
+
+  ASSERT_EQ(1, measureCount);
+
+  YGNodeFreeRecursive(root);
+}
+
 #if GTEST_HAS_DEATH_TEST
 TEST(YogaTest, cannot_add_child_to_node_with_measure_func) {
   const YGNodeRef root = YGNodeNew();
diff --git a/yoga/Yoga.c b/yoga/Yoga.c
index 4ebafec6..51a9287c 100644
--- a/yoga/Yoga.c
+++ b/yoga/Yoga.c
@@ -1431,11 +1431,10 @@ static void YGNodeAbsoluteLayoutChild(const YGNodeRef node,
     childHeightMeasureMode =
         YGFloatIsUndefined(childHeight) ? YGMeasureModeUndefined : YGMeasureModeExactly;
 
-    // According to the spec, if the main size is not definite and the
-    // child's inline axis is parallel to the main axis (i.e. it's
-    // horizontal), the child should be sized using "UNDEFINED" in
-    // the main size. Otherwise use "AT_MOST" in the cross axis.
-    if (!isMainAxisRow && YGFloatIsUndefined(childWidth) && widthMode != YGMeasureModeUndefined) {
+    // If the size of the parent is defined then try to constrain the absolute child to that size
+    // as well. This allows text within the absolute child to wrap to the size of its parent.
+    // This is the same behavior as many browsers implement.
+    if (!isMainAxisRow && YGFloatIsUndefined(childWidth) && widthMode != YGMeasureModeUndefined && width > 0) {
       childWidth = width;
       childWidthMeasureMode = YGMeasureModeAtMost;
     }