[Bug c++/92789] Non-obvious ?: behaviour with structurally equivalent types

[rsandifo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92789

--- Comment #5 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> 
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Keeping open since the problem also affects arm*-*-*.  I don't
think we should change GCC 10 and earlier though.