Before adding QQmlPropertyData (imo better to be named as AttributeData to minimize confusion and have corresponding views like Property, Method, etc.) to PropertyCache we check override semantics. The adding happens in 2 steps: adding data, making it accessible by name.

Currently in both cases (filling up PropertyCache from IR and from MetaObject ) we add QQmlPropertyData even in cases when "check fails". It's not clear why we actually need to do that and it introduces confusion to the expectations of the PropertyCache... like the append/addition is still happening, but the data is not exposed.

Most likely at least for the IR side for the properties it can easily be removed, since there is an early exit in that function and error-out. Other cases need to be assessed.