https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105709
--- Comment #10 from Sam James <sam at gentoo dot org> --- Thanks Siddhesh. I was suspicious of how contorted the minimised version was but I went with it given it still crashed. And I think I get what the issue is with the original code now too. Cheers for explaining. I've reported this to Qt at https://bugreports.qt.io/browse/QTBUG-103782.
