;; The widening thunk is memoised per signature, and the key is the types.
;;
;; It used to be a *name*, derived from mangle_ty, which flattens a whole
;; signature into one hyphen-joined string and loses arity and every type
;; boundary with it: (CFn [(Ptr i32)] i32) and (CFn [ptr i32] i32) — the
;; second over a struct someone called ptr — both flatten to the same thing.
;; Keyed on that, the second widening reuses the first's thunk and calls it
;; with the wrong arity, which both backends compile without a word and
;; neither runs. This program is that pair, and it prints 5 and 17.
;;
;; A struct named ptr is legal and ordinary; nothing about the collision
;; needed a program written to provoke it, only two signatures that happened
;; to flatten alike.
(defstruct ptr [a i32  b i32])

(defn f1 [p (Ptr i32)] i32 (deref p))
(defn f2 [a ptr  b i32] i32 (+ (.a a) b))

(defn use1 [f (Fn [(Ptr i32)] i32)] i32 (let [x 5] (f (addr x))))
(defn use2 [f (Fn [ptr i32] i32)] i32 (f (ptr {.a 10 .b 0}) 7))

(defn main [] i32
  (println (use1 f1))
  (println (use2 f2))
  0)