(*  let d := default_val _ in *)

Lemma nested_sfieldlist_at_ramif: forall sh t gfs id a i v p,
let d := default_val _ in
nested_field_type t gfs = Tstruct id a ->
in_members i (co_members (get_co id)) ->
nested_sfieldlist_at sh t gfs (co_members (get_co id)) v p |--
field_at sh t (StructField i :: gfs)
(proj_struct i (co_members (get_co id)) v d) p *
(ALL v0: _,
field_at sh t (StructField i :: gfs) v0 p -*
nested_sfieldlist_at sh t gfs (co_members (get_co id))
(upd_struct i (co_members (get_co id)) v v0) p).