Goal:
  
  A : Type
  R : ReflectEq A
  x : A
  y : A
  Heq_anonymous : false = (x == y)
  H : x = y
  ============================
   False


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