Remark permutation_norepet:
forall (A: Type) (l l': list A), Permutation l l' -> list_norepet l -> list_norepet l'.

Lemma build_compilenv_sound:
forall f cenv sz,
build_compilenv f = (cenv, sz) ->
list_norepet (map fst (Csharpminor.fn_vars f)) ->
cenv_compat cenv (Csharpminor.fn_vars f) sz /\ cenv_separated cenv (Csharpminor.fn_vars f).