Require Import MSets.
Require Import Orders.

Declare Module Signal : OrderedType.

Module S := MSetAVL.Make(Signal).
Module Sdec := Decide(S).
Export Sdec.

Hint Extern 0 (Signal.eq ?x ?y) => now symmetry.

Goal forall o s, Signal.eq o s.
Proof. fsetdec. Qed.