Lemma cast_exists : forall {CS: compspecs} Delta e2 t rho phi (TC: typecheck_environ Delta rho), denote_tc_assert (typecheck_expr Delta e2) rho phi -> denote_tc_assert (isCastResultType (typeof e2) t e2) rho phi -> sem_cast (typeof e2) t (eval_expr e2 rho) = Some (force_val (sem_cast (typeof e2) t (eval_expr e2 rho))).