Add a workaround for the parsing of long identifiers.

ocamliface/mlcompat_411_12.ml

 (* Compatibilty for OCaml 4.11 & 4.12 *)
 open Cduce_core
-
+let () =Printexc.record_backtrace true
 let longident_parse s =
-  let open Ocaml_common in
-  match String.index_opt s '.' with
-  | None -> Longident.Lident s
-  | _    -> Parse.longident (Lexing.from_string s)
+    let open Ocaml_common in
+    let rec loop first s =
+     match String.rindex_opt s '.' with
+   | None -> Longident.Lident s
+   | Some i    -> 
+      try
+        Parse.longident (Lexing.from_string s)
+      with
+        _ -> try
+          Parse.val_ident (Lexing.from_string s)
+        with
+        _ -> try Parse.constr_ident (Lexing.from_string s) with
+        | e -> (* last resort *)
+        if first then
+          let p, s = String.sub s 0 i, String.sub s (i+1) (String.length s - i - 1) in
+          let s = p ^".(" ^ s ^")" in
+          loop false s
+        else raise e
+      in loop true s
+        
 
 module Mlstub = struct
   let noloc id = Some id