https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125541
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> --- members_of(...)[0] is the type, that is mangled according to the https://itanium-cxx-abi.github.io/cxx-abi/abi.html#mangling.named rule: <unnamed-type-name> ::= Ut [ <nonnegative number> ] _ (note, the ABI says "and that aren't anonymous union types" which is ignored). But members_of(...)[1] here is the unnamed non-static data member with that type, and the mangling of that is the cause of the ICE here.
