Add empty action function to Target

src/bin/sail.ml

@@ -333,7 +333,7 @@ let rec options =
       ("--help", Arg.Unit (fun () -> help !options), " display this list of options");
     ]
 
-let register_default_target () = Target.register ~name:"default" (fun _ _ _ _ _ _ -> ())
+let register_default_target () = Target.register ~name:"default" Target.empty_action
 
 let run_sail (config : Yojson.Basic.t option) tgt =
   Target.run_pre_parse_hook tgt ();

src/lib/target.ml

@@ -123,6 +123,8 @@ let register ~name ?flag ?description:desc ?(options = []) ?(pre_parse_hook = fu
   targets := StringMap.add name tgt !targets;
   tgt
 
+let empty_action _ _ _ _ _ _ = ()
+
 let get_the_target () = match !the_target with Some name -> StringMap.find_opt name !targets | None -> None
 
 let get ~name = StringMap.find_opt name !targets

src/lib/target.mli

@@ -128,6 +128,10 @@ val register :
   (Yojson.Basic.t option -> string -> string option -> tannot ast -> Effects.side_effect_info -> Env.t -> unit) ->
   target
 
+(** Use if you want to register a target that does nothing *)
+val empty_action :
+  Yojson.Basic.t option -> string -> string option -> tannot ast -> Effects.side_effect_info -> Env.t -> unit
+
 (** Return the current target. For example, if we register a 'coq'
    target, and Sail is invoked with `sail -coq`, then this function
    will return the coq target. *)