import QtQuick 2.12
import QtQuick.Controls 2.5

ApplicationWindow {
    visible: true
    component MyText: Text {
        id: myText
        property alias foo: myText.text
        property string bar
        text: bar
    }

    MyText {
        foo: "ok"
    }
    MyText {
        Binding on bar {
            value: "ok"
        }
    }
    MyText {
        id: myText
        Binding {
            target: myText
            property: "foo"
            value: "ok"
        }
    }
    MyText {
        Binding on foo {
            value: "ko" // QQmlApplicationEngine failed to load component
        }               // qrc:/main.qml:30:20: Cannot assign to non-existent property "foo"
    }
}