Fix stack layout index when loaded asynchronously

Lazy loading of stack layout causes incorrect index value in the
attached property for the child items. This is because,
attachedProperties are created and updated for the child object, after
being added to the stack layout.

This patchset triggers childItemsChanged() to reset child objects of
stack layout with right index value.

Fixes: QTBUG-111902
Change-Id: Iad06d028d0f977189b5da1122904dc754060a609
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>
(cherry picked from commit e397e5b43c9a9844e652adf5ef55365e0a40f57b)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 32 insertions, 0 deletions

diff --git a/tests/auto/quick/qquicklayouts/data/tst_stacklayout.qml b/tests/auto/quick/qquicklayouts/data/tst_stacklayout.qml
index e8d311183e..99713991bd 100644
--- a/tests/auto/quick/qquicklayouts/data/tst_stacklayout.qml
+++ b/tests/auto/quick/qquicklayouts/data/tst_stacklayout.qml
@@ -724,6 +724,38 @@ Item {
             compare(layout.num_onCountChanged, 1)
         }
 
+        // QTBUG-111902
+        Component {
+            id: stackComponent
+            Loader {
+                id: loader
+                asynchronous: true
+                sourceComponent: StackLayout {
+                    id: stackLayout
+                    Repeater {
+                        model: 3
+                        Item {
+                            required property int index
+                        }
+                    }
+                }
+            }
+        }
 
+        function test_loadStackLayoutAsynchronously() {
+            var loaderObj = stackComponent.createObject(container)
+            // Check for loader status to be ready
+            tryCompare(loaderObj, 'status', 1)
+            // Get stack layout object
+            var stackLayoutObj = loaderObj.item
+            // Check repeater index of child object
+            compare(stackLayoutObj.children[0].index, 0)
+            compare(stackLayoutObj.children[1].index, 1)
+            compare(stackLayoutObj.children[2].index, 2)
+            // Check stack layout attached property index
+            compare(stackLayoutObj.children[0].StackLayout.index, 0)
+            compare(stackLayoutObj.children[1].StackLayout.index, 1)
+            compare(stackLayoutObj.children[2].StackLayout.index, 2)
+        }
     }
 }