False "Layout must be attached to Item elements" warning

Consider the following QML code:

import QtQuick
import QtQuick.Layouts

Item {
    property list<Item> knownItems: []
    property int foo: knownItems[0].Layout.preferredWidth
} 

qmllint warns

Warning: test.qml:6:23: Layout must be attached to Item elements [Quick.attached-property-type]
    property int foo: knownItems[0].Layout.preferredWidth
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

However since knownItems is a list of Items knownItems[0] is an Item, so I expect Layout to be available, which it is at runtime. When changing the type from list<Item> to var the warning disappears.

qtdeclarative commit 41a97f06981144ef80a3faf8925753f15c0ff3c6