Fix warning and assert when removing items from groups

When removing items from groups actively shown by a model filter a warning
and assert was triggered in the past. This change fixes this behavior.

Fixes: QTBUG-86017
Change-Id: I49b7498a3d03141b654e453a3c35a43fc7ba804a
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

4 files changed, 53 insertions, 1 deletions

diff --git a/src/qmlmodels/qqmldelegatemodel.cpp b/src/qmlmodels/qqmldelegatemodel.cpp
index 303ca0e2e4..838a0e18e2 100644
--- a/src/qmlmodels/qqmldelegatemodel.cpp
+++ b/src/qmlmodels/qqmldelegatemodel.cpp
@@ -1340,6 +1340,8 @@ QObject *QQmlDelegateModel::object(int index, QQmlIncubator::IncubationMode incu
 QQmlIncubator::Status QQmlDelegateModel::incubationStatus(int index)
 {
     Q_D(QQmlDelegateModel);
+    if (d->m_compositor.count(d->m_compositorGroup) <= index)
+        return QQmlIncubator::Null;
     Compositor::iterator it = d->m_compositor.find(d->m_compositorGroup, index);
     if (!it->inCache())
         return QQmlIncubator::Null;
diff --git a/src/quick/items/qquickitemview.cpp b/src/quick/items/qquickitemview.cpp
index 95b5415ef0..f1336a91f6 100644
--- a/src/quick/items/qquickitemview.cpp
+++ b/src/quick/items/qquickitemview.cpp
@@ -2346,7 +2346,9 @@ FxViewItem *QQuickItemViewPrivate::createItem(int modelIndex, QQmlIncubator::Inc
 
     inRequest = true;
 
-    QObject* object = model->object(modelIndex, incubationMode);
+    // The model will run this same range check internally but produce a warning and return nullptr.
+    // Since we handle this result graciously in our code, we preempt this warning by checking the range ourselves.
+    QObject* object = modelIndex < model->count() ? model->object(modelIndex, incubationMode) : nullptr;
     QQuickItem *item = qmlobject_cast<QQuickItem*>(object);
 
     if (!item) {
diff --git a/tests/auto/qml/qqmldelegatemodel/data/qtbug_86017.qml b/tests/auto/qml/qqmldelegatemodel/data/qtbug_86017.qml
new file mode 100644
index 0000000000..02d737e37f
--- /dev/null
+++ b/tests/auto/qml/qqmldelegatemodel/data/qtbug_86017.qml
@@ -0,0 +1,32 @@
+import QtQuick 2.8
+import QtQml.Models 2.1
+
+DelegateModel {
+    id: visualModel
+    model: ListModel {
+        id: myLM
+        ListElement {
+            name: "Apple"
+        }
+        ListElement {
+            name: "Orange"
+        }
+    }
+
+    filterOnGroup: "selected"
+
+    groups: [
+        DelegateModelGroup {
+            name: "selected"
+            includeByDefault: true
+        }
+    ]
+
+    delegate: Text {
+        Component.onCompleted: {
+            DelegateModel.inPersistedItems = true
+            DelegateModel.inSelected = false
+        }
+        text: "item " + index
+    }
+}
diff --git a/tests/auto/qml/qqmldelegatemodel/tst_qqmldelegatemodel.cpp b/tests/auto/qml/qqmldelegatemodel/tst_qqmldelegatemodel.cpp
index 87f42c0c8a..8e6d147028 100644
--- a/tests/auto/qml/qqmldelegatemodel/tst_qqmldelegatemodel.cpp
+++ b/tests/auto/qml/qqmldelegatemodel/tst_qqmldelegatemodel.cpp
@@ -42,6 +42,7 @@ public:
 private slots:
     void valueWithoutCallingObjectFirst_data();
     void valueWithoutCallingObjectFirst();
+    void qtbug_86017();
 };
 
 class AbstractItemModel : public QAbstractItemModel
@@ -134,6 +135,21 @@ void tst_QQmlDelegateModel::valueWithoutCallingObjectFirst()
     QCOMPARE(model->variantValue(index, role), expectedValue);
 }
 
+void tst_QQmlDelegateModel::qtbug_86017()
+{
+    QQmlEngine engine;
+    QQmlComponent component(&engine);
+    component.loadUrl(testFileUrl("qtbug_86017.qml"));
+    QScopedPointer<QObject> root(component.create());
+    QVERIFY2(root, qPrintable(component.errorString()));
+    QTRY_VERIFY(component.isReady());
+    QQmlDelegateModel *model = qobject_cast<QQmlDelegateModel*>(root.data());
+
+    QVERIFY(model);
+    QCOMPARE(model->count(), 2);
+    QCOMPARE(model->filterGroup(), "selected");
+}
+
 QTEST_MAIN(tst_QQmlDelegateModel)
 
 #include "tst_qqmldelegatemodel.moc"