-;;; like INDEX, but augmented with -1 (useful when using the index
-;;; to count downwards to 0, e.g. LOOP FOR I FROM N DOWNTO 0, with
-;;; an implementation which terminates the loop by testing for the
-;;; index leaving the loop range)
-(sb!xc:deftype index-or-minus-1 () `(integer -1 ,(1- most-positive-fixnum)))
-