Hint Resolve check_rval_wt check_lval_wt: ty.
Hint Extern 1 (wt_expr _ _ _) => (unfold wt_expr; simpl): ty.

Lemma sfor_sound:
forall s1 a s2 s3 s, sfor s1 a s2 s3 = OK s ->
wt_stmt ce e rt s1 -> wt_expr ce e a -> wt_stmt ce e rt s2 -> wt_stmt ce e rt s3 ->
wt_stmt ce e rt s.