Goal:
    A : Type  HA : ReflectEq A  x : option A  y : option A
  ============================
   (reflectProp (x = y) (eq_option eqb x y))


DEBUG:Going to execute:
match goal with
           | H:?x <> ?x |- _ => elim H; Ltac.reflexivity
           | _ => discriminate
           end