+ (flet ((fun-type-simple-p (type)
+ (not (or (fun-type-rest type)
+ (fun-type-keyp type))))
+ (every-csubtypep (types1 types2)
+ (loop
+ for a1 in types1
+ for a2 in types2
+ do (multiple-value-bind (res sure-p)
+ (csubtypep a1 a2)
+ (unless res (return (values res sure-p))))
+ finally (return (values t t)))))
+ (macrolet ((3and (x y)
+ `(multiple-value-bind (val1 win1) ,x
+ (if (and (not val1) win1)
+ (values nil t)
+ (multiple-value-bind (val2 win2) ,y
+ (if (and val1 val2)
+ (values t t)
+ (values nil (and win2 (not val2)))))))))
+ (3and (values-subtypep (fun-type-returns type1)
+ (fun-type-returns type2))
+ (cond ((fun-type-wild-args type2) (values t t))
+ ((fun-type-wild-args type1)
+ (cond ((fun-type-keyp type2) (values nil nil))
+ ((not (fun-type-rest type2)) (values nil t))
+ ((not (null (fun-type-required type2))) (values nil t))
+ (t (3and (type= *universal-type* (fun-type-rest type2))
+ (every/type #'type= *universal-type*
+ (fun-type-optional type2))))))
+ ((not (and (fun-type-simple-p type1)
+ (fun-type-simple-p type2)))
+ (values nil nil))
+ (t (multiple-value-bind (min1 max1) (fun-type-nargs type1)
+ (multiple-value-bind (min2 max2) (fun-type-nargs type2)
+ (cond ((or (> max1 max2) (< min1 min2))
+ (values nil t))
+ ((and (= min1 min2) (= max1 max2))
+ (3and (every-csubtypep (fun-type-required type1)
+ (fun-type-required type2))
+ (every-csubtypep (fun-type-optional type1)
+ (fun-type-optional type2))))
+ (t (every-csubtypep
+ (concatenate 'list
+ (fun-type-required type1)
+ (fun-type-optional type1))
+ (concatenate 'list
+ (fun-type-required type2)
+ (fun-type-optional type2)))))))))))))