Crash when declaring an alias to a readonly object-typed subproperty

The following code snippet leads to an instant segfault:

import QtQml 2.15

QtObject {
    id: obj

    readonly property QtObject subObj: QtObject {
        property bool foo: false
    }

    readonly property QtObject subObj2: QtObject {
        property alias foo: obj.subObj.foo
    }
}

As I understand QML, this should not even go through the parser, because the alias declaration refers to a subproperty of a readonly property (readonly, but not not constant! i.e. it could still change through bindings, internal shenanigans...).