Instance CompSpecs : compspecs. make_compspecs prog. Defined.
Definition Vprog : varspecs. mk_varspecs prog. Defined.
Definition Gprog : funspecs :=
ltac:(with_library prog (@nil(ident*funspec))).
Definition g_spec :=
DECLARE _g
WITH i: Z
PRE [ _i OF size_t]
PROP() LOCAL(temp _i (Vptrofs (Ptrofs.repr i))) SEP()
POST [ size_t ]
PROP() LOCAL (temp ret_temp (Vptrofs (Ptrofs.repr i))) SEP().

Lemma body_g: semax_body Vprog Gprog f_g g_spec.