Only eagerly evaluate serialization / deserialization functions for n…

…ative or bytecode backends

melange_test/dune

@@ -1,6 +1,6 @@
 (melange.emit
  (target output)
- (libraries ocaml-protoc-plugin)
+ ;(libraries ocaml-protoc-plugin)
 )
 
 

src/ocaml_protoc_plugin/ocaml_protoc_plugin.ml

@@ -16,3 +16,12 @@ module Service = Service
 module Result = Result
 module Extensions = Extensions
 module Json_options = Json_options
+
+
+let apply_lazy f =
+  match Sys.backend_type with
+  | Native | Bytecode ->
+    f ()
+  | Other _ ->
+    let f = Lazy.from_fun f in
+    fun x -> (Lazy.force f) x

src/plugin/emit.ml

@@ -298,22 +298,22 @@ let rec emit_message ~params ~syntax ~scope
       Code.emit implementation `None "let spec () = %s" spec_str;
 
       Code.emit implementation `Begin "let to_proto' =";
-      Code.emit implementation `None "let serialize = Runtime'.Serialize.serialize (spec ()) in";
+      Code.emit implementation `None "let serialize = Runtime'.apply_lazy (fun () -> Runtime'.Serialize.serialize (spec ())) in";
       Code.emit implementation `None "fun writer %s -> serialize writer %s" destructor (String.concat ~sep:" " args);
       Code.emit implementation `End "";
 
       Code.emit implementation `None "let to_proto t = let writer = Runtime'.Writer.init () in to_proto' writer t; writer";
 
       Code.emit implementation `Begin "let from_proto_exn =";
       Code.emit implementation `None "let constructor %s = %s in" (String.concat ~sep:" " args) destructor;
-      Code.emit implementation `None "Runtime'.Deserialize.deserialize (spec ()) constructor";
+      Code.emit implementation `None "Runtime'.apply_lazy (fun () -> Runtime'.Deserialize.deserialize (spec ()) constructor)";
       Code.emit implementation `End "let from_proto writer = Runtime'.Result.catch (fun () -> from_proto_exn writer)";
       Code.emit implementation `Begin "let to_json options = ";
       Code.emit implementation `None "let serialize = Runtime'.Serialize_json.serialize ~message_name:(name ()) (spec ()) options in";
       Code.emit implementation `None "fun %s -> serialize %s" destructor (String.concat ~sep:" " args);
       Code.emit implementation `EndBegin "let from_json_exn =";
       Code.emit implementation `None "let constructor %s = %s in" (String.concat ~sep:" " args) destructor;
-      Code.emit implementation `None "Runtime'.Deserialize_json.deserialize ~message_name:(name ()) (spec ()) constructor";
+      Code.emit implementation `None "Runtime'.apply_lazy (fun () -> Runtime'.Deserialize_json.deserialize ~message_name:(name ()) (spec ()) constructor)";
       Code.emit implementation `End "let from_json json = Runtime'.Result.catch (fun () -> from_json_exn json)";
     | None -> ()
   in