QQmlTableInstanceModel: don't fall back to use DelegateChooser as delegate

If the application uses a DelegateChooser, but the chooser fails to
resolve a delegate for a certain index, it should not use itself
as the delegate instead. This will cause the application to crash.
Instead, we just print a warning, and return nullptr, which will let
TableView handle the situation gracefully.

Change-Id: Ibaf9da09fd11149362f5b674fc61db47593de10c
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

1 files changed, 6 insertions, 4 deletions

diff --git a/src/qml/types/qqmltableinstancemodel.cpp b/src/qml/types/qqmltableinstancemodel.cpp
index 33d13e3bad..1054158dc8 100644
--- a/src/qml/types/qqmltableinstancemodel.cpp
+++ b/src/qml/types/qqmltableinstancemodel.cpp
@@ -109,19 +109,19 @@ QQmlTableInstanceModel::~QQmlTableInstanceModel()
 
 QQmlComponent *QQmlTableInstanceModel::resolveDelegate(int index)
 {
-    QQmlComponent *delegate = nullptr;
     if (m_delegateChooser) {
         const int row = m_adaptorModel.rowAt(index);
         const int column = m_adaptorModel.columnAt(index);
+        QQmlComponent *delegate = nullptr;
         QQmlAbstractDelegateComponent *chooser = m_delegateChooser;
         do {
             delegate = chooser->delegate(&m_adaptorModel, row, column);
             chooser = qobject_cast<QQmlAbstractDelegateComponent *>(delegate);
         } while (chooser);
+        return delegate;
     }
-    if (!delegate)
-        delegate = m_delegate;
-    return delegate;
+
+    return m_delegate;
 }
 
 QQmlDelegateModelItem *QQmlTableInstanceModel::resolveModelItem(int index)
@@ -132,6 +132,8 @@ QQmlDelegateModelItem *QQmlTableInstanceModel::resolveModelItem(int index)
         return modelItem;
 
     QQmlComponent *delegate = resolveDelegate(index);
+    if (!delegate)
+        return nullptr;
 
     // Check if the pool contains an item that can be reused
     modelItem = takeFromReusableItemsPool(delegate);