;;;; A slice built backwards, for the survey rather than for a person.
;;;;
;;;; test/programs/bounds.flan already covers this, and cannot cover it here:
;;;; it picks its case out of (at args 1) and survey.sh runs every program
;;;; with no arguments at all. So the one backend comparison that would catch
;;;; check_slice's lo <= hi being re-gated on --no-bounds-checks is a program
;;;; that reaches the reversed slice on its own.
;;;;
;;;; What it pins is that both backends die here in *every* build. lo <= hi is
;;;; not a bounds check — it is the claim that the length word of the %slice
;;;; this expression builds is a count, and hi - lo is -1 — so
;;;; --no-bounds-checks has nothing here to drop, and running this sweep with
;;;; SURVEY_FLAGS=--no-bounds-checks must report the same MATCH as without it.
;;;; A backend that quietly builds the slice exits 0 while the other exits 134
;;;; and the survey says DIFFER.
;;;;
;;;; The two ends come from (len args), which is 1 for a program run with no
;;;; arguments and is not a number either optimiser can see, so the branch
;;;; cannot be folded away and the checker has no literal to object to.
(defn main [args [string]] i32
  (let [s (bytes "hello")
        hi (i32 (len args))
        lo (+ hi 1)]
    (print (slice s lo hi))
    (println ""))
  0)