Instance CompSpecs : compspecs. make_compspecs prog. Defined.
Definition Vprog : varspecs. mk_varspecs prog. Defined.
Instance LS: listspec _list _tail (fun _ _ => emp).

(* TODO-LTAC - is this a missing lemma of the theory of [list_cell]?*)
Lemma list_cell_field_at sh (v : val) p :
list_cell LS sh v p = field_at sh list_struct [StructField _head] v p.