https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91064
--- Comment #4 from Martin Sebor <msebor at gcc dot gnu.org> --- Yes, my example in comment #0 is missing the derivation from Q. So the sentence has at most one base class subobject of any given type doesn't mean that a std layout class cannot have multiple base class subobjects, just that none of them can be of a type that's derived, either directly or indirectly, from the same base class. Okay, thanks.