Compatibility with OCaml 4.05.0.

src/Visitors.ml

@@ -387,7 +387,7 @@ let ty_env =
 
 let tyvar_visitor_method_type =
   if X.poly "env" then
-    Typ.poly ["env"] (ty_arrow ty_env ty_any)
+    typ_poly ["env"] (ty_arrow ty_env ty_any)
   else
     ty_any
 
@@ -538,7 +538,7 @@ let quantify (alphas : tyvars) (ty : core_type) : core_type =
       alphas
   in
   (* Done. *)
-  Typ.poly alphas ty
+  typ_poly alphas ty
 
 (* -------------------------------------------------------------------------- *)
 

src/VisitorsCompatibility.cppo.ml

+let mknoloc = Location.mknoloc
 open Asttypes
 open Parsetree
 open Ast_helper
@@ -68,3 +69,21 @@ let data_constructor_variety (cd : constructor_declaration) =
     | Pcstr_record lds ->
         DataInlineRecord (ld_labels lds, ld_tys lds)
   #endif
+
+(* Between OCaml 4.04 and OCaml 4.05, the types of several functions in [Ast_helper]
+   have changed. They used to take arguments of type [string], and now take arguments
+   of type [str], thus requiring a conversion. These functions include [Typ.object_],
+   [Typ.poly], [Exp.send], [Exp.newtype], [Ctf.val_], [Ctf.method_], [Cf.inherit_].  *)
+
+let string2str (s : string) =
+  #if OCAML_VERSION < (4, 05, 0)
+    s
+  #else
+    mknoloc s
+  #endif
+
+let typ_poly (tyvars : string list) (cty : core_type) : core_type =
+  Typ.poly (List.map string2str tyvars) cty
+
+let exp_send (e : expression) (m : string) : expression =
+  Exp.send e (string2str m)

src/VisitorsGeneration.ml

@@ -467,7 +467,7 @@ let is_virtual (Meth (_, _, oe, _)) : bool =
 (* [send o m es] produces a call to the method [o#m] with arguments [es]. *)
 
 let send (o : variable) (m : methode) (es : expressions) : expression =
-  app (Exp.send (evar o) m) es
+  app (exp_send (evar o) m) es
 
 (* -------------------------------------------------------------------------- *)