QML: Guard QProperty change triggers against deletion of target

Previously, we relied on QObject* pointers being unique even after
deletion of the objects. That's not good.

Pick-to: 6.6 6.5 6.2
Fixes: QTBUG-114329
Change-Id: Ia0a2c1d2cb5d8a0d47ec00e73424c959c59c09bc
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 50 insertions, 0 deletions

diff --git a/tests/auto/qml/qqmlproperty/data/invalidateQPropertyChangeTriggers.qml b/tests/auto/qml/qqmlproperty/data/invalidateQPropertyChangeTriggers.qml
new file mode 100644
index 0000000000..bfa832c1c8
--- /dev/null
+++ b/tests/auto/qml/qqmlproperty/data/invalidateQPropertyChangeTriggers.qml
@@ -0,0 +1,50 @@
+import QtQml
+
+QtObject {
+    id: root
+    objectName: column.text
+
+    property Component c: Component {
+        id: comp
+        QtObject { }
+    }
+
+    property QtObject rectItem: null
+
+    property bool running: false
+
+    property Timer t: Timer {
+        id: column
+        interval: 200
+        running: root.running
+        repeat: true
+
+        property string text: {
+            let item = root.rectItem
+            let result = rectItem ? rectItem.objectName : "Create Object"
+            return result
+        }
+
+        onTriggered: {
+            let rectItem = root.rectItem
+
+            // If rectItem exists destory it.
+            if (rectItem) {
+                rectItem.destroy()
+                return
+            }
+
+            // Otherwise create a new object
+            let newRectItem = comp.createObject(column, {})
+
+
+            // Setting the objectName before setting root.rectItem seems to work.
+            // newRectItem.width = 1200
+            root.rectItem = newRectItem
+
+            // But setting the objectName after setting root.rectItem seems to
+            // cause the issue.
+            newRectItem.objectName = "1300"
+        }
+    }
+}