https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64670
--- Comment #4 from Jason Merrill <jason at gcc dot gnu.org> --- This seems like a bug in the user's code, not the compiler. If the class is defined in a header with #pragma interface, there needs to be a matching #pragma implementation somewhere to cause the typeinfo and such to be emitted. clang doesn't run into this because it just ignores #pragma interface.
