Code completion for function return types doesn't work reliably

E.g. When the following C++ function is exported to QML:

QString doSomething();

QtCreator can provide you a code-completion for all string operations. e.g. by doing doSomething()<Tab>

If the same is done with a complex type it doesn't work:

QQuickItem* doSomething();

The expected behavior would be to list all operations/properties of a QQuickitem in the completion.

If doSomething() is not a function, but a property, the completion works fine for some types e.g. QQuickItem, but also stops working when builtin-types or GADGETS are returned e.g. QRectF

The behavior can already be tested using either: Qt.vector2d() or QQuickItem::childAt() from QML