AnchorChanges uses QQmlScriptString

import QtQuick

Window {
    id: root
    width: 640
    height: 480
    visible: true
    title: "Foo"

    Text {
        id: label

        states: [
            State {
                when: true
                AnchorChanges {
                   target: item
                   anchors.top: label.bottom
                }
            }
        ]

        anchors.top: parent.top
    }

    Item {
        id: item
    }
} 

 Warning: main.qml:18:33: Cannot assign binding of type QQuickAnchorLine to QQmlScriptString
                   anchors.top: label.bottom
                                ^^^^^^^^^^^^
Error: main.qml:18:45: Could not compile binding for top: cannot convert from QQuickAnchorLine of QQuickItem::bottom with type QQuickAnchorLine to QQmlScriptString of QQmlScriptString