;;;; spec-memory.md, "Dev builds detect a released region".
;;;;
;;;; A Vec records the epoch of the allocator it was made with, and free-all
;;;; bumps that counter. Any operation on a container whose recorded epoch has
;;;; moved traps, naming the site. This is the shipping answer to the section
;;;; the spec leaves open — detection, loud and immediate, rather than the
;;;; static prevention that with-allocator and context/allocator deny.
;;;;
;;;; It is a separate counter from the per-Vec generation word, which answers a
;;;; different question (a stale slice), and the two must not be conflated.
(defn main [] i32
  (let [a (arena-new 4096)]
    (let [v (vec-new i32 a)]
      (push v 1)
      (push v 2)
      (println (at v 1))
      ;; The region goes. v is still in scope and still looks fine — nothing
      ;; is released at scope exit and nothing marked v — which is exactly the
      ;; case a static rule cannot see.
      (free-all a)
      (println (at v 1))))
  0)