QML Item::mapToItem parameter count not checked

The number of arguments in QML function Item::mapToItem is not checked properly. The documentation defines a 3 parameter and a 5 parameter signature.

When you use 2 or 4 parameters, the behaviour is undefined but no error is shown. This is caused by a vague case distinction in QQuickItem::mapToItem(QQmlV4Function *args)

// Line 3983
        if (args->length() > 3) {
            // case A
        } else {
            // case B
        }

This is especially problematically because the QML function can be confused with the C++ function QQuickItem::mapToItem(const QQuickItem *, const QPointF &).

See also problem description on Stack Overflow.

The same goes for mapFromItem