Consider the following code:

// Referential.qml
import QtQuick
Rectangle {
    id: self
    property Referential ref: self
}

Running qmllint on it yields

Warning: Referential.qml:5:31: Cannot assign binding of type Rectangle to Referential 

[incompatible-type]

That's obviously wrong; qmllint picks up the base type instead of the elements actual type.