Corollary check_rval_wt:
  forall a x, wt_expr ce e a -> check_rval a = OK x -> wt_rvalue ce e a.Corollary check_lval_wt:
  forall a x, wt_expr ce e a -> check_lval a = OK x -> wt_lvalue ce e a.

Lemma binarith_type_int32s: forall ty1 msg ty2, binarith_type ty1 type_int32s msg = OK ty2 -> ty2 = incrdecr_type ty1.