+
+;; 5d3a728 broke something like this in CL-PPCRE
+(test-util:with-test (:name :fold-index-addressing-potentially-negative-index)
+ (compile nil `(lambda (index vector)
+ (declare (optimize speed (safety 0))
+ ((simple-array character (*)) vector)
+ ((unsigned-byte 24) index))
+ (aref vector (1+ (mod index (1- (length vector))))))))