Nothing visible on CPAN uses either. Passing either to Perl_get_vtbl() will
currently return NULL (as a runtime error, rather than a compile time error).
The case for want_vtbl_glob was removed from the switch in Perl_get_vtbl() in
c0c446747ad6c5bd (which eliminated the need for magic on typeglobs).
want_vtbl_symtab was added to the enum in perl.h with
8d2f45362e368d7d, but
no code was added to Perl_get_vtbl() as there is no corresponding vtable.
want_vtbl_isa,
want_vtbl_isaelem,
want_vtbl_arylen,
- want_vtbl_glob,
want_vtbl_mglob,
want_vtbl_nkeys,
want_vtbl_taint,
want_vtbl_regdatum,
want_vtbl_backref,
want_vtbl_utf8,
- want_vtbl_symtab,
want_vtbl_arylen_p,
want_vtbl_hintselem,
want_vtbl_hints