Prevent errors when removing items from Repeater that reference parent.

Use the same ordering as item views and release before unparenting.

Change-Id: I0346342cfcaf9385d8385769795dd5ba35fc43aa
Task-number: QTBUG-46828
Reviewed-by: Liang Qi <liang.qi@theqtcompany.com>
Reviewed-by: Robin Burchell <robin.burchell@viroteck.net>

src/quick/items/qquickrepeater.cpp

@@ -361,8 +361,8 @@ void QQuickRepeater::clear()
             if (QQuickItem *item = d->deletables.at(i)) {
                 if (complete)
                     emit itemRemoved(i, item);
-                item->setParentItem(0);
                 d->model->release(item);
+                item->setParentItem(0);
             }
         }
     }
@@ -466,8 +466,8 @@ void QQuickRepeater::modelUpdated(const QQmlChangeSet &changeSet, bool reset)
             d->deletables.remove(index);
             emit itemRemoved(index, item);
             if (item) {
-                item->setParentItem(0);
                 d->model->release(item);
+                item->setParentItem(0);
             }
             --d->itemCount;
         }

tests/auto/quick/qquickrepeater/data/modelCleared.qml

@@ -0,0 +1,17 @@
+import QtQuick 2.0
+
+Row {
+    spacing: 2
+    height: 100
+
+    Repeater {
+        id: repeater
+        objectName: "repeater"
+        model: 10
+        Rectangle {
+            color: "green"
+            width: 10; height: 50
+            anchors.bottom: parent.bottom
+        }
+    }
+}

tests/auto/quick/qquickrepeater/tst_qquickrepeater.cpp

@@ -68,6 +68,7 @@ private slots:
     void resetModel();
     void modelChanged();
     void modelReset();
+    void modelCleared();
     void properties();
     void asynchronous();
     void initParent();
@@ -634,6 +635,26 @@ void tst_QQuickRepeater::modelReset()
     QCOMPARE(addedSpy.count(), 0);
 }
 
+// QTBUG-46828
+void tst_QQuickRepeater::modelCleared()
+{
+    QQmlEngine engine;
+    QQmlComponent component(&engine, testFileUrl("modelCleared.qml"));
+
+    QQuickItem *rootObject = qobject_cast<QQuickItem*>(component.create());
+    QVERIFY(rootObject);
+
+    QQuickRepeater *repeater = findItem<QQuickRepeater>(rootObject, "repeater");
+    QVERIFY(repeater);
+
+    // verify no error messages when the model is cleared and the items are destroyed
+    QQmlTestMessageHandler messageHandler;
+    repeater->setModel(0);
+    QVERIFY2(messageHandler.messages().isEmpty(), qPrintable(messageHandler.messageString()));
+
+    delete rootObject;
+}
+
 void tst_QQuickRepeater::properties()
 {
     QQmlEngine engine;