Dune, dynlink, and undefined symbol

Hello.

I have this interface for plugins to register plugins in my program:

let ht : (string, (string * (_ -> _ -> bool))) Hashtbl.t  = Hashtbl.create 0
let assets = ref ""
let register ~ns m fn = let fn = fn !assets in Hashtbl.add ht m (ns, fn)
let get = Hashtbl.find_opt ht

Then I have the main executable loading plugins this way:

let register_plugin dir =
  let assets = Filename.concat dir "assets" in
  GwdPlugin.assets := assets ;
  Secure.add_lang_path assets ;
  Dynlink.loadfile (Filename.concat dir "plugin.cmxs") ;
  GwdPlugin.assets := ""

But I have a lot of problems when trying to use libraries which are not included in my main program.

I tried to use embed_in_plugin_libraries and -linkall. Each time I get un undefined symbol, I add the corresponding lib in embed_in_plugin_libraries.

(executable
  (name plugin)
  (libraries aaa)
  (embed_in_plugin_libraries bbb ccc ddd)
  (flags -linkall)
  (modes (native plugin))
)

aaa si the library of my main program (plugin registration + the rest of its world), bbb ccc ddd libraries not used in the main program.

But now, I am stuck because the undefined symbol is actually

undefined symbol: camlStdlib__lexing__engine_113

• Is it possible for my main program to link the whole stdlib without the compiler removing ? It is ok for me to state that the main program to embed unused code if it is only the stdlib (maybe this would be sufficent to solve the issue)
• Is it possible for my plugin to embed stdlib as I did it with other libs ? Can’t find a package for this.
• Am I just doing it wrong?

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