Goal:
  
  ============================
   (forall (A : Type) (R : ReflectEq A) (x y : A), true = (x == y) -> x = y)


DEBUG:Going to execute:
simpl; intros; Tactics.destruct_all_rec_calls;
            repeat (Tactics.destruct_conjs; simpl proj1_sig in *); subst *;
            Tactics.autoinjections; try Tactics.discriminates