+
+;;; Ca. sbcl-0.7.5.15 the compiler would fail an internal consistency
+;;; check on this code because it expected all calls to %INSTANCE-REF
+;;; to be transformed away, but its expectations were dashed by perverse
+;;; code containing app programmer errors like this.
+(defstruct something-known-to-be-a-struct x y)
+(multiple-value-bind (fun warnings-p failure-p)
+ (compile nil
+ '(lambda ()
+ (labels ((a1 (a2 a3)
+ (cond (t (a4 a2 a3))))
+ (a4 (a2 a3 a5 a6)
+ (declare (type (or simple-vector null) a5 a6))
+ (something-known-to-be-a-struct-x a5))
+ (a8 (a2 a3)
+ (a9 #'a1 a10 a2 a3))
+ (a11 (a2 a3)
+ (cond ((and (funcall a12 a2)
+ (funcall a12 a3))
+ (funcall a13 a2 a3))
+ (t
+ (when a14
+ (let ((a15 (a1 a2 a3)))
+ ))
+ a16))))
+ (values #'a17 #'a11))))
+ ;; Python sees the structure accessor on the known-not-to-be-a-struct
+ ;; A5 value and is very, very disappointed in you. (But it doesn't
+ ;; signal BUG any more.)
+ (assert failure-p))