+(defun function-type (function-designator)
+ "Returns the ftype of FUNCTION-DESIGNATOR, or NIL."
+ (flet ((ftype-of (function-designator)
+ (sb-kernel:type-specifier
+ (sb-int:info :function :type function-designator))))
+ (etypecase function-designator
+ (symbol
+ (when (and (fboundp function-designator)
+ (not (macro-function function-designator))
+ (not (special-operator-p function-designator)))
+ (ftype-of function-designator)))
+ (cons
+ (when (and (sb-int:legal-fun-name-p function-designator)
+ (fboundp function-designator))
+ (ftype-of function-designator)))
+ (generic-function
+ (function-type (sb-pcl:generic-function-name function-designator)))
+ (function
+ ;; Give declared type in globaldb priority over derived type
+ ;; because it contains more accurate information e.g. for
+ ;; struct-accessors.
+ (let ((type (function-type (sb-kernel:%fun-name
+ (sb-impl::%fun-fun function-designator)))))
+ (if type
+ type
+ (sb-impl::%fun-type function-designator)))))))
+