Goal:
    A : Type  R : ReflectEq A  x : A  y : A  Heq_anonymous : false = (x == y)
  ============================
   (x <> y)


DEBUG:Going to execute:
match goal with
           | H:let _ := fixproto in _
             |- _ => red in H; CoreTactics.destruct_calls H; clear H
           end