While a normal QML scene should not feature extremely deep object trees, one can still encounter them in some test cases. Those test cases might then run out of (C++) stack space with the previous recursive version of markAsDeleted. Thus, we change the implementation to use an explicit workqueue instead of relying on recursion. This changes the visitation order, but code is not supposed to rely on the order of Component.onDestroyed calls anyway (and we keep at least the order in so far that the parent emits the "signal" before it's children. Pick-to: 6.5 Change-Id: I93b30cc26b984d1a21cff92df1dd68cd45e67477 Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io> Reviewed-by: Ulf Hermann <ulf.hermann@qt.io> Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>