cffi gets stuck in a loop when returning a struct containing a slot with a typedef of a bitfield

[3b]

(cffi:defbitfield foo-)
(cffi:defctype foo foo-)
(cffi:defcstruct sfoo
  (foo foo))

(cffi:defcfun foo (:struct sfoo))
(foo)
;; doesn't return, expected error about undefined function

apparently caused by LIBFFI-TYPE-POINTER calling FOLLOW-TYPEDEF on an ENHANCED-TYPEDEF expecting to get back the referenced type, but instead getting back the original type because FOLLOR-TYPEDEF checks for (eq (type-of type) 'foreign-typedef) rather than TYPEP

v0.15, sbcl linux/windows

[3b (00003b)]

actually, doesn't work on bitfields without the typedef as well, since they are also subclasses of FOREIGN-TYPEDEF.

[Luís Oliveira (luismbo)]

There was initial attempt at fixing this that broke foreign-aref and friends, so it was reverted by <https://github.com/cffi/cffi/pull/79>.