+ (let ((ftype (specifier-type 'function)))
+ (cond ((eq type1 ftype) type2)
+ ((eq type2 ftype) type1)
+ (t (let ((rtype (values-type-intersection (fun-type-returns type1)
+ (fun-type-returns type2))))
+ (flet ((change-returns (ftype rtype)
+ (declare (type fun-type ftype) (type ctype rtype))
+ (make-fun-type :required (fun-type-required ftype)
+ :optional (fun-type-optional ftype)
+ :keyp (fun-type-keyp ftype)
+ :keywords (fun-type-keywords ftype)
+ :allowp (fun-type-allowp ftype)
+ :returns rtype)))
+ (cond
+ ((fun-type-wild-args type1)
+ (if (fun-type-wild-args type2)
+ (make-fun-type :wild-args t
+ :returns rtype)
+ (change-returns type2 rtype)))
+ ((fun-type-wild-args type2)
+ (change-returns type1 rtype))
+ (t (multiple-value-bind (req opt rest)
+ (args-type-op type1 type2 #'type-intersection #'max)
+ (make-fun-type :required req
+ :optional opt
+ :rest rest
+ ;; FIXME: :keys
+ :allowp (and (fun-type-allowp type1)
+ (fun-type-allowp type2))
+ :returns rtype))))))))))