https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117993
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> --- (In reply to Andrew Pinski from comment #3) > I suspect for some reason we think the current instantiation does not have a > dependent base for some reason. That is any_dependent_bases_p is returning false for `struct B<T>::C<n>` type.