(**** tactics for value_fits  ****)

Lemma value_fits_by_value_defined:
forall {cs: compspecs} t t' v r,
type_is_by_value t = true ->
repinject t v <> Vundef  ->
t = t' ->
(r = if type_is_volatile t' then True
else tc_val t' (repinject t v)) ->
value_fits t v = r.