Canonical Zchar_opprPred := OpprPred Zchar_zmod.
Canonical Zchar_addrPred := AddrPred Zchar_zmod.
Canonical Zchar_zmodPred := ZmodPred Zchar_zmod.

(* A special lemma is needed because trivial fails to use the cfun_onT Hint. *)
Lemma mem_zchar S phi : phi \in S -> phi \in 'Z[S].