Calling Qt.binding() on a bound function object is a valid use case and used to work until Qt 5.8. The problem was that we optimized the code in QQmlBinding and QQmlJavascriptExpression to directly work on a QV4::Function, so this wouldn't work anymore. To fix this make sure recursive calls to Function.bind() are unrolled (so that the BoundFunction's target is never a bound function itself), then add the bound function as an optional member to the QQmlBinding and use it's bound arguments if present. Task-number: QTBUG-61927 Change-Id: I472214ddd82fc2a1212efd9b769861fc43d2ddaf Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>