Index: VERSION
===================================================================
--- VERSION	(リビジョン 11207)
+++ VERSION	(作業コピー)
@@ -1,4 +1,4 @@
-3.13.0+dev6 (2011-07-29)
+3.13.0+dev7 (2011-09-22)
 
 # The version string is the first line of this file.
 # It must be in the format described in stdlib/sys.mli
Index: typing/typemod.ml
===================================================================
--- typing/typemod.ml	(リビジョン 11207)
+++ typing/typemod.ml	(作業コピー)
@@ -764,7 +764,7 @@
               Location.prerr_warning smod.pmod_loc
                 (Warnings.Not_principal "this module unpacking");
             modtype_of_package env smod.pmod_loc p nl tl
-        | {desc = Tvar} ->
+        | {desc = Tvar _} ->
             raise (Typecore.Error
                      (smod.pmod_loc, Typecore.Cannot_infer_signature))
         | _ ->
Index: typing/typetexp.ml
===================================================================
--- typing/typetexp.ml	(リビジョン 11207)
+++ typing/typetexp.ml	(作業コピー)
@@ -150,7 +150,7 @@
     if strict then raise Already_bound;
     v
   with Not_found ->
-    let v = new_global_var() in
+    let v = new_global_var ~name () in
     type_variables := Tbl.add name v !type_variables;
     v
 
@@ -165,8 +165,8 @@
     Tpoly _ -> ty
   | _ -> Ctype.newty (Tpoly (ty, []))
 
-let new_pre_univar () =
-  let v = newvar () in pre_univars := v :: !pre_univars; v
+let new_pre_univar ?name () =
+  let v = newvar ?name () in pre_univars := v :: !pre_univars; v
 
 let rec swap_list = function
     x :: y :: l -> y :: x :: swap_list l
@@ -190,7 +190,8 @@
         instance (fst(Tbl.find name !used_variables))
       with Not_found ->
         let v =
-          if policy = Univars then new_pre_univar () else newvar () in
+          if policy = Univars then new_pre_univar ~name () else newvar ~name ()
+        in
         used_variables := Tbl.add name (v, styp.ptyp_loc) !used_variables;
         v
       end
@@ -333,7 +334,14 @@
             end_def ();
             generalize_structure t;
           end;
-          instance t
+          let t = instance t in
+          let px = Btype.proxy t in
+          begin match px.desc with
+          | Tvar None -> Btype.log_type px; px.desc <- Tvar (Some alias)
+          | Tunivar None -> Btype.log_type px; px.desc <- Tunivar (Some alias)
+          | _ -> ()
+          end;
+          t
       end
   | Ptyp_variant(fields, closed, present) ->
       let name = ref None in
@@ -388,7 +396,7 @@
               {desc=Tvariant row}, _ when Btype.static_row row ->
                 let row = Btype.row_repr row in
                 row.row_fields
-            | {desc=Tvar}, Some(p, _) ->
+            | {desc=Tvar _}, Some(p, _) ->
                 raise(Error(sty.ptyp_loc, Unbound_type_constructor_2 p))
             | _ ->
                 raise(Error(sty.ptyp_loc, Not_a_variant ty))
@@ -431,7 +439,7 @@
       newty (Tvariant row)
   | Ptyp_poly(vars, st) ->
       begin_def();
-      let new_univars = List.map (fun name -> name, newvar()) vars in
+      let new_univars = List.map (fun name -> name, newvar ~name ()) vars in
       let old_univars = !univars in
       univars := new_univars @ !univars;
       let ty = transl_type env policy st in
@@ -443,10 +451,12 @@
           (fun tyl (name, ty1) ->
             let v = Btype.proxy ty1 in
             if deep_occur v ty then begin
-              if v.level <> Btype.generic_level || v.desc <> Tvar then
-                raise (Error (styp.ptyp_loc, Cannot_quantify (name, v)));
-              v.desc <- Tunivar;
-              v :: tyl
+              match v.desc with
+                Tvar name when v.level = Btype.generic_level ->
+                  v.desc <- Tunivar name;
+                  v :: tyl
+              | _ ->
+                raise (Error (styp.ptyp_loc, Cannot_quantify (name, v)))
             end else tyl)
           [] new_univars
       in
@@ -483,7 +493,7 @@
     match ty.desc with
     | Tvariant row ->
         let row = Btype.row_repr row in
-        if (Btype.row_more row).desc = Tunivar then
+        if Btype.is_Tunivar (Btype.row_more row) then
           ty.desc <- Tvariant
               {row with row_fixed=true;
                row_fields = List.map
@@ -512,7 +522,7 @@
       then try
         r := (loc, v,  Tbl.find name !type_variables) :: !r
       with Not_found ->
-        if fixed && (repr ty).desc = Tvar then
+        if fixed && Btype.is_Tvar (repr ty) then
           raise(Error(loc, Unbound_type_variable ("'"^name)));
         let v2 = new_global_var () in
         r := (loc, v, v2) :: !r;
@@ -552,8 +562,10 @@
     List.fold_left
       (fun acc v ->
         let v = repr v in
-        if v.level <> Btype.generic_level || v.desc <> Tvar then acc
-        else (v.desc <- Tunivar ; v :: acc))
+        match v.desc with
+          Tvar name when v.level = Btype.generic_level ->
+            v.desc <- Tunivar name; v :: acc
+        | _ -> acc)
       [] !pre_univars
   in
   make_fixed_univars typ;
@@ -635,8 +647,8 @@
       fprintf ppf "The type variable name %s is not allowed in programs" name
   | Cannot_quantify (name, v) ->
       fprintf ppf "This type scheme cannot quantify '%s :@ %s." name
-        (if v.desc = Tvar then "it escapes this scope" else
-         if v.desc = Tunivar then "it is aliased to another variable"
+        (if Btype.is_Tvar v then "it escapes this scope" else
+         if Btype.is_Tunivar v then "it is aliased to another variable"
          else "it is not a variable")
   | Multiple_constraints_on_type s ->
       fprintf ppf "Multiple constraints for type %s" s
Index: typing/btype.ml
===================================================================
--- typing/btype.ml	(リビジョン 11207)
+++ typing/btype.ml	(作業コピー)
@@ -35,9 +35,9 @@
 let new_id = ref (-1)
 
 let newty2 level desc  =
-  incr new_id; { desc = desc; level = level; id = !new_id }
+  incr new_id; { desc; level; id = !new_id }
 let newgenty desc      = newty2 generic_level desc
-let newgenvar ()       = newgenty Tvar
+let newgenvar ?name () = newgenty (Tvar name)
 (*
 let newmarkedvar level =
   incr new_id; { desc = Tvar; level = pivot_level - level; id = !new_id }
@@ -46,6 +46,11 @@
   { desc = Tvar; level = pivot_level - generic_level; id = !new_id }
 *)
 
+(**** Check some types ****)
+
+let is_Tvar = function {desc=Tvar _} -> true | _ -> false
+let is_Tunivar = function {desc=Tunivar _} -> true | _ -> false
+
 (**** Representative of a type ****)
 
 let rec field_kind_repr =
@@ -139,7 +144,7 @@
       let rec proxy_obj ty =
         match ty.desc with
           Tfield (_, _, _, ty) | Tlink ty -> proxy_obj ty
-        | Tvar | Tunivar | Tconstr _ -> ty
+        | Tvar _ | Tunivar _ | Tconstr _ -> ty
         | Tnil -> ty0
         | _ -> assert false
       in proxy_obj ty
@@ -180,13 +185,13 @@
     row.row_fields;
   match (repr row.row_more).desc with
     Tvariant row -> iter_row f row
-  | Tvar | Tunivar | Tsubst _ | Tconstr _ ->
+  | Tvar _ | Tunivar _ | Tsubst _ | Tconstr _ ->
       Misc.may (fun (_,l) -> List.iter f l) row.row_name
   | _ -> assert false
 
 let iter_type_expr f ty =
   match ty.desc with
-    Tvar                -> ()
+    Tvar _              -> ()
   | Tarrow (_, ty1, ty2, _) -> f ty1; f ty2
   | Ttuple l            -> List.iter f l
   | Tconstr (_, l, _)   -> List.iter f l
@@ -198,7 +203,7 @@
   | Tnil                -> ()
   | Tlink ty            -> f ty
   | Tsubst ty           -> f ty
-  | Tunivar             -> ()
+  | Tunivar _           -> ()
   | Tpoly (ty, tyl)     -> f ty; List.iter f tyl
   | Tpackage (_, _, l)  -> List.iter f l
 
@@ -239,13 +244,13 @@
    encoding during substitution *)
 let rec norm_univar ty =
   match ty.desc with
-    Tunivar | Tsubst _ -> ty
+    Tunivar _ | Tsubst _ -> ty
   | Tlink ty           -> norm_univar ty
   | Ttuple (ty :: _)   -> norm_univar ty
   | _                  -> assert false
 
 let rec copy_type_desc f = function
-    Tvar                -> Tvar
+    Tvar _              -> Tvar None (* forget the name *)
   | Tarrow (p, ty1, ty2, c)-> Tarrow (p, f ty1, f ty2, copy_commu c)
   | Ttuple l            -> Ttuple (List.map f l)
   | Tconstr (p, l, _)   -> Tconstr (p, List.map f l, ref Mnil)
@@ -258,7 +263,7 @@
   | Tnil                -> Tnil
   | Tlink ty            -> copy_type_desc f ty.desc
   | Tsubst ty           -> assert false
-  | Tunivar             -> Tunivar
+  | Tunivar _ as ty     -> ty (* keep the name *)
   | Tpoly (ty, tyl)     ->
       let tyl = List.map (fun x -> norm_univar (f x)) tyl in
       Tpoly (f ty, tyl)
@@ -447,7 +452,7 @@
   | Cuniv of type_expr option ref * type_expr option
 
 let undo_change = function
-    Ctype  (ty, desc)  -> ty.desc <- desc
+    Ctype  (ty, desc) -> ty.desc <- desc
   | Clevel (ty, level) -> ty.level <- level
   | Cname  (r, v) -> r := v
   | Crow   (r, v) -> r := v
@@ -474,7 +479,22 @@
 
 let log_type ty =
   if ty.id <= !last_snapshot then log_change (Ctype (ty, ty.desc))
-let link_type ty ty' = log_type ty; ty.desc <- Tlink ty'
+let link_type ty ty' =
+  log_type ty;
+  let desc = ty.desc in
+  ty.desc <- Tlink ty';
+  (* Name is a user-supplied name for this unification variable (obtained
+   * through a type annotation for instance). *)
+  match desc, ty'.desc with
+    Tvar name, Tvar name' ->
+      begin match name, name' with
+      | Some _, None ->  log_type ty'; ty'.desc <- Tvar name
+      | None, Some _ ->  ()
+      | Some _, Some _ ->
+          if ty.level < ty'.level then (log_type ty'; ty'.desc <- Tvar name)
+      | None, None   ->  ()
+      end
+  | _ -> ()
   (* ; assert (check_memorized_abbrevs ()) *)
   (*  ; check_expans [] ty' *)
 let set_level ty level =
Index: typing/typecore.ml
===================================================================
--- typing/typecore.ml	(リビジョン 11207)
+++ typing/typecore.ml	(作業コピー)
@@ -633,7 +633,7 @@
           List.iter generalize vars;
           let instantiated tv  = 
             let tv = expand_head !env tv in
-            tv.desc <> Tvar || tv.level <> generic_level in
+            not (is_Tvar tv) || tv.level <> generic_level in
           if List.exists instantiated vars then
             raise (Error(loc, Polymorphic_label (lid_of_label label)))
         end;
@@ -1126,7 +1126,7 @@
     Tarrow (l, _, ty_res, _) ->
       list_labels_aux env (ty::visited) (l::ls) ty_res
   | _ ->
-      List.rev ls, ty.desc = Tvar
+      List.rev ls, is_Tvar ty
 
 let list_labels env ty = list_labels_aux env [] [] ty
 
@@ -1142,9 +1142,10 @@
       (fun t ->
         let t = repr t in
         generalize t;
-        if t.desc = Tvar && t.level = generic_level then
-          (log_type t; t.desc <- Tunivar; true)
-        else false)
+        match t.desc with
+          Tvar name when t.level = generic_level ->
+            log_type t; t.desc <- Tunivar name; true
+        | _ -> false)
       vars in
   if List.length vars = List.length vars' then () else
   let ty = newgenty (Tpoly(repr exp.exp_type, vars'))
@@ -1158,7 +1159,7 @@
   match (expand_head env exp.exp_type).desc with
   | Tarrow _ ->
       Location.prerr_warning exp.exp_loc Warnings.Partial_application
-  | Tvar -> ()
+  | Tvar _ -> ()
   | Tconstr (p, _, _) when Path.same p Predef.path_unit -> ()
   | _ ->
       if statement then
@@ -1742,7 +1743,7 @@
               let (id, typ) =
                 filter_self_method env met Private meths privty
               in
-              if (repr typ).desc = Tvar then
+              if is_Tvar (repr typ) then
                 Location.prerr_warning loc
                   (Warnings.Undeclared_virtual_method met);
               (Texp_send(obj, Tmeth_val id), typ)
@@ -1797,7 +1798,7 @@
                 Location.prerr_warning loc
                   (Warnings.Not_principal "this use of a polymorphic method");
               snd (instance_poly false tl ty)
-          | {desc = Tvar} as ty ->
+          | {desc = Tvar _} as ty ->
               let ty' = newvar () in
               unify env (instance ty) (newty(Tpoly(ty',[])));
               (* if not !Clflags.nolabels then
@@ -1979,7 +1980,7 @@
             end_def ();
             check_univars env false "method" exp ty_expected vars;
             re { exp with exp_type = instance ty }
-        | Tvar ->
+        | Tvar _ ->
             let exp = type_exp env sbody in
             let exp = {exp with exp_type = newty (Tpoly (exp.exp_type, []))} in
             unify_exp env exp ty;
@@ -2038,7 +2039,7 @@
               Location.prerr_warning loc
                 (Warnings.Not_principal "this module packing");
             (p, nl, tl)
-        | {desc = Tvar} ->
+        | {desc = Tvar _} ->
             raise (Error (loc, Cannot_infer_signature))
         | _ ->
             raise (Error (loc, Not_a_packed_module ty_expected))
@@ -2128,7 +2129,7 @@
               ty_fun
         | Tarrow (l,_,ty_res',_) when l = "" || !Clflags.classic ->
             args, ty_fun, no_labels ty_res'
-        | Tvar ->  args, ty_fun, false
+        | Tvar _ ->  args, ty_fun, false
         |  _ -> [], texp.exp_type, false
       in
       let args, ty_fun', simple_res = make_args [] texp.exp_type in
@@ -2192,7 +2193,7 @@
         let (ty1, ty2) =
           let ty_fun = expand_head env ty_fun in
           match ty_fun.desc with
-            Tvar ->
+            Tvar _ ->
               let t1 = newvar () and t2 = newvar () in
               let not_identity = function
                   Texp_ident(_,{val_kind=Val_prim
@@ -2335,7 +2336,7 @@
       begin match (expand_head env exp.exp_type).desc with
       | Tarrow _ ->
           Location.prerr_warning exp.exp_loc Warnings.Partial_application
-      | Tvar ->
+      | Tvar _ ->
           add_delayed_check (fun () -> check_application_result env false exp)
       | _ -> ()
       end;
@@ -2404,9 +2405,9 @@
   | Tarrow _ ->
       Location.prerr_warning loc Warnings.Partial_application
   | Tconstr (p, _, _) when Path.same p Predef.path_unit -> ()
-  | Tvar when ty.level > tv.level ->
+  | Tvar _ when ty.level > tv.level ->
       Location.prerr_warning loc Warnings.Nonreturning_statement
-  | Tvar ->
+  | Tvar _ ->
       add_delayed_check (fun () -> check_application_result env true exp)
   | _ ->
       Location.prerr_warning loc Warnings.Statement_type
Index: typing/btype.mli
===================================================================
--- typing/btype.mli	(リビジョン 11207)
+++ typing/btype.mli	(作業コピー)
@@ -23,7 +23,7 @@
         (* Create a type *)
 val newgenty: type_desc -> type_expr
         (* Create a generic type *)
-val newgenvar: unit -> type_expr
+val newgenvar: ?name:string -> unit -> type_expr
         (* Return a fresh generic variable *)
 
 (* Use Tsubst instead
@@ -33,6 +33,9 @@
         (* Return a fresh marked generic variable *)
 *)
 
+val is_Tvar: type_expr -> bool
+val is_Tunivar: type_expr -> bool
+
 val repr: type_expr -> type_expr
         (* Return the canonical representative of a type. *)
 
Index: typing/ctype.mli
===================================================================
--- typing/ctype.mli	(リビジョン 11207)
+++ typing/ctype.mli	(作業コピー)
@@ -41,9 +41,10 @@
         (* This pair of functions is only used in Typetexp *)
 
 val newty: type_desc -> type_expr
-val newvar: unit -> type_expr
+val newvar: ?name:string -> unit -> type_expr
+val newvar2: ?name:string -> int -> type_expr
         (* Return a fresh variable *)
-val new_global_var: unit -> type_expr
+val new_global_var: ?name:string -> unit -> type_expr
         (* Return a fresh variable, bound at toplevel
            (as type variables ['a] in type constraints). *)
 val newobj: type_expr -> type_expr
Index: typing/datarepr.ml
===================================================================
--- typing/datarepr.ml	(リビジョン 11207)
+++ typing/datarepr.ml	(作業コピー)
@@ -28,7 +28,7 @@
     if ty.level >= lowest_level then begin
       ty.level <- pivot_level - ty.level;
       match ty.desc with
-      | Tvar ->
+      | Tvar _ ->
           ret := TypeSet.add ty !ret
       | Tvariant row ->
           let row = row_repr row in
Index: typing/typeclass.ml
===================================================================
--- typing/typeclass.ml	(リビジョン 11207)
+++ typing/typeclass.ml	(作業コピー)
@@ -532,7 +532,7 @@
                 (Typetexp.transl_simple_type val_env false sty) ty
           end;
           begin match (Ctype.repr ty).desc with
-            Tvar ->
+            Tvar _ ->
               let ty' = Ctype.newvar () in
               Ctype.unify val_env (Ctype.newty (Tpoly (ty', []))) ty;
               Ctype.unify val_env (type_approx val_env sbody) ty'
Index: typing/typedecl.ml
===================================================================
--- typing/typedecl.ml	(リビジョン 11207)
+++ typing/typedecl.ml	(作業コピー)
@@ -111,7 +111,7 @@
     | _ ->
         raise (Error (loc, Bad_fixed_type "is not an object or variant"))
   in
-  if rv.desc <> Tvar then
+  if not (Btype.is_Tvar rv) then
     raise (Error (loc, Bad_fixed_type "has no row variable"));
   rv.desc <- Tconstr (p, decl.type_params, ref Mnil)
 
@@ -503,7 +503,7 @@
           compute_same row.row_more
       | Tpoly (ty, _) ->
           compute_same ty
-      | Tvar | Tnil | Tlink _ | Tunivar -> ()
+      | Tvar _ | Tnil | Tlink _ | Tunivar _ -> ()
       | Tpackage (_, _, tyl) ->
           List.iter (compute_variance_rec true true true) tyl
     end
@@ -546,7 +546,7 @@
   in
   List.iter2
     (fun (ty, co, cn, ct) (c, n) ->
-      if ty.desc <> Tvar then begin
+      if not (Btype.is_Tvar ty) then begin
         co := c; cn := n; ct := n;
         compute_variance env tvl2 c n n ty
       end)
@@ -571,7 +571,7 @@
 
 let rec anonymous env ty =
   match (Ctype.expand_head env ty).desc with
-  | Tvar -> false
+  | Tvar _ -> false
   | Tobject (fi, _) ->
       let _, rv = Ctype.flatten_fields fi in anonymous env rv
   | Tvariant row ->
Index: typing/types.mli
===================================================================
--- typing/types.mli	(リビジョン 11207)
+++ typing/types.mli	(作業コピー)
@@ -24,7 +24,7 @@
     mutable id: int }
 
 and type_desc =
-    Tvar
+    Tvar of string option
   | Tarrow of label * type_expr * type_expr * commutable
   | Ttuple of type_expr list
   | Tconstr of Path.t * type_expr list * abbrev_memo ref
@@ -34,7 +34,7 @@
   | Tlink of type_expr
   | Tsubst of type_expr         (* for copying *)
   | Tvariant of row_desc
-  | Tunivar
+  | Tunivar of string option
   | Tpoly of type_expr * type_expr list
   | Tpackage of Path.t * string list * type_expr list
 
Index: typing/ctype.ml
===================================================================
--- typing/ctype.ml	(リビジョン 11207)
+++ typing/ctype.ml	(作業コピー)
@@ -153,9 +153,9 @@
 let newty desc         = newty2 !current_level desc
 let new_global_ty desc = newty2 !global_level desc
 
-let newvar ()          = newty2 !current_level Tvar
-let newvar2 level      = newty2 level Tvar
-let new_global_var ()  = newty2 !global_level Tvar
+let newvar ?name ()         = newty2 !current_level (Tvar name)
+let newvar2 ?name level     = newty2 level (Tvar name)
+let new_global_var ?name () = newty2 !global_level (Tvar name)
 
 let newobj fields      = newty (Tobject (fields, ref None))
 
@@ -297,14 +297,12 @@
 
 let opened_object ty =
   match (object_row ty).desc with
-  | Tvar               -> true
-  | Tunivar            -> true
-  | Tconstr _          -> true
-  | _                  -> false
+  | Tvar _  | Tunivar _ | Tconstr _ -> true
+  | _                               -> false
 
 let concrete_object ty =
   match (object_row ty).desc with
-  | Tvar               -> false
+  | Tvar _             -> false
   | _                  -> true
 
 (**** Close an object ****)
@@ -313,7 +311,7 @@
   let rec close ty =
     let ty = repr ty in
     match ty.desc with
-      Tvar ->
+      Tvar _ ->
         link_type ty (newty2 ty.level Tnil)
     | Tfield(_, _, _, ty') -> close ty'
     | _                    -> assert false
@@ -329,7 +327,7 @@
     let ty = repr ty in
     match ty.desc with
       Tfield (_, _, _, ty) -> find ty
-    | Tvar                 -> ty
+    | Tvar _               -> ty
     | _                    -> assert false
   in
   match (repr ty).desc with
@@ -434,7 +432,7 @@
     let level = ty.level in
     ty.level <- pivot_level - level;
     match ty.desc with
-      Tvar when level <> generic_level ->
+      Tvar _ when level <> generic_level ->
         raise Non_closed
     | Tfield(_, kind, t1, t2) ->
         if field_kind_repr kind = Fpresent then
@@ -468,7 +466,7 @@
   if ty.level >= lowest_level then begin
     ty.level <- pivot_level - ty.level;
     begin match ty.desc, !really_closed with
-      Tvar, _ ->
+      Tvar _, _ ->
         free_variables := (ty, real) :: !free_variables
     | Tconstr (path, tl, _), Some env ->
         begin try
@@ -639,7 +637,7 @@
 let rec generalize_structure var_level ty =
   let ty = repr ty in
   if ty.level <> generic_level then begin
-    if ty.desc = Tvar && ty.level > var_level then
+    if is_Tvar ty && ty.level > var_level then
       set_level ty var_level
     else if ty.level > !current_level then begin
       set_level ty generic_level;
@@ -858,7 +856,7 @@
           TypeHash.add node_univars inv.inv_type (ref(TypeSet.singleton univ));
           List.iter (add_univar univ) inv.inv_parents
   in
-  TypeHash.iter (fun ty inv -> if ty.desc = Tunivar then add_univar ty inv)
+  TypeHash.iter (fun ty inv -> if is_Tunivar ty then add_univar ty inv)
     inverted;
   fun ty ->
     try !(TypeHash.find node_univars ty) with Not_found -> TypeSet.empty
@@ -913,7 +911,7 @@
             if keep then ty.level else !current_level
           else generic_level
     in
-    if forget <> generic_level then newty2 forget Tvar else
+    if forget <> generic_level then newty2 forget (Tvar None) else
     let desc = ty.desc in
     save_desc ty desc;
     let t = newvar() in          (* Stub *)
@@ -959,7 +957,7 @@
                 | Tconstr _ ->
                     if keep then save_desc more more.desc;
                     copy more
-                | Tvar | Tunivar ->
+                | Tvar _ | Tunivar _ ->
                     save_desc more more.desc;
                     if keep then more else newty more.desc
                 |  _ -> assert false
@@ -1117,7 +1115,7 @@
     t
   else try
     let t, bound_t = List.assq ty visited in
-    let dl = if ty.desc = Tunivar then [] else diff_list bound bound_t in
+    let dl = if is_Tunivar ty then [] else diff_list bound bound_t in
     if dl <> [] && conflicts univars dl then raise Not_found;
     t
   with Not_found -> begin
@@ -1134,14 +1132,14 @@
           let row = row_repr row0 in
           let more = repr row.row_more in
           (* We shall really check the level on the row variable *)
-          let keep = more.desc = Tvar && more.level <> generic_level in
+          let keep = is_Tvar more && more.level <> generic_level in
           let more' = copy_rec more in
-          let fixed' = fixed && (repr more').desc = Tvar in
+          let fixed' = fixed && is_Tvar (repr more') in
           let row = copy_row copy_rec fixed' row keep more' in
           Tvariant row
       | Tpoly (t1, tl) ->
           let tl = List.map repr tl in
-          let tl' = List.map (fun t -> newty Tunivar) tl in
+          let tl' = List.map (fun t -> newty t.desc) tl in
           let bound = tl @ bound in
           let visited =
             List.map2 (fun ty t -> ty,(t,bound)) tl tl' @ visited in
@@ -1395,7 +1393,7 @@
 let rec full_expand env ty =
   let ty = repr (expand_head env ty) in
   match ty.desc with
-    Tobject (fi, {contents = Some (_, v::_)}) when (repr v).desc = Tvar ->
+    Tobject (fi, {contents = Some (_, v::_)}) when is_Tvar (repr v) ->
       newty2 ty.level (Tobject (fi, ref None))
   | _ ->
       ty
@@ -1570,8 +1568,8 @@
         true
     then
       match ty.desc with
-        Tunivar ->
-          if not (TypeSet.mem ty bound) then raise (Unify [ty, newgenvar()])
+        Tunivar _ ->
+          if not (TypeSet.mem ty bound) then raise (Unify [ty, newgenvar ()])
       | Tpoly (ty, tyl) ->
           let bound = List.fold_right TypeSet.add (List.map repr tyl) bound in
           occur_rec bound  ty
@@ -1620,7 +1618,7 @@
         Tpoly (t, tl) ->
           if List.exists (fun t -> TypeSet.mem (repr t) family) tl then ()
           else occur t
-      | Tunivar ->
+      | Tunivar _ ->
           if TypeSet.mem t family then raise Occur
       | Tconstr (_, [], _) -> ()
       | Tconstr (p, tl, _) ->
@@ -1784,7 +1782,7 @@
               t
           end;
         iter_type_expr (iterator visited) ty
-    | Tvar -> 
+    | Tvar _ -> 
         let t = create_fresh_constr ty.level false in
         link_type ty t
     | _ ->
@@ -1862,8 +1860,8 @@
   let t2 = repr t2 in
   if t1 == t2 then () else
     match (t1.desc, t2.desc) with
-      | (Tvar, _)  
-      | (_, Tvar)  ->
+      | (Tvar _, _)  
+      | (_, Tvar _)  ->
         fatal_error "types should not include variables"
       | (Tconstr (p1, [], _), Tconstr (p2, [], _)) when Path.same p1 p2 ->
         ()
@@ -1877,7 +1875,7 @@
           with Not_found ->
               TypePairs.add type_pairs (t1', t2') ();
               match (t1'.desc, t2'.desc) with
-                  (Tvar, Tvar) ->
+                  (Tvar _, Tvar _) ->
                     fatal_error "types should not include variables"
                 | (Tarrow (l1, t1, u1, _), Tarrow (l2, t2, u2, _)) when l1 = l2
                   || !Clflags.classic && not (is_optional l1 || is_optional l2) ->
@@ -1903,7 +1901,7 @@
                 | (Tpoly (t1, tl1), Tpoly (t2, tl2)) ->
                   enter_poly env univar_pairs t1 tl1 t2 tl2
                     (mcomp type_pairs subst env)
-                | (Tunivar, Tunivar) ->
+                | (Tunivar _, Tunivar _) ->
                   unify_univar t1' t2' !univar_pairs
                 | (_, _) ->
                   raise (Unify [])
@@ -2048,21 +2046,21 @@
   try
     type_changed := true;
     match (t1.desc, t2.desc) with
-      (Tvar, Tconstr _) when deep_occur t1 t2 ->
+      (Tvar _, Tconstr _) when deep_occur t1 t2 ->
         unify2 env t1 t2
-    | (Tconstr _, Tvar) when deep_occur t2 t1 ->
+    | (Tconstr _, Tvar _) when deep_occur t2 t1 ->
         unify2 env t1 t2
-    | (Tvar, _) ->
+    | (Tvar _, _) ->
         occur !env t1 t2; 
         occur_univar !env t2;
         link_type t1 t2;
         update_level !env t1.level t2
-    | (_, Tvar) ->
+    | (_, Tvar _) ->
         occur !env t2 t1; 
         occur_univar !env t1;
         link_type t2 t1;
         update_level !env t2.level t1
-    | (Tunivar, Tunivar) ->
+    | (Tunivar _, Tunivar _) ->
         unify_univar t1 t2 !univar_pairs;
         update_level !env t1.level t2;
         link_type t1 t2
@@ -2104,7 +2102,7 @@
   (* Assumes either [t1 == t1'] or [t2 != t2'] *)
   let d1 = t1'.desc and d2 = t2'.desc in
   match (d1, d2) with (* handle univars specially *)
-    (Tunivar, Tunivar) ->
+    (Tunivar _, Tunivar _) ->
       unify_univar t1' t2' !univar_pairs;
       update_level !env t1'.level t2';
       link_type t1' t2'
@@ -2127,12 +2125,12 @@
     | Old -> f () (* old_link was already called *)
   in
   match d1, d2 with
-  | Tvar,_ ->
+  | Tvar _, _ ->
       occur !env t1 t2';
       occur_univar !env t2;
       update_level !env t1'.level t2;
       link_type t1' t2;      
-  | _, Tvar ->
+  | _, Tvar _ ->
       occur !env t2 t1';
       occur_univar !env t1;
       update_level !env t2'.level t1;
@@ -2149,8 +2147,8 @@
           add_type_equality t1' t2' end;
       try
         begin match (d1, d2) with
-        | (Tvar, _) 
-        | (_, Tvar) ->
+        | (Tvar _, _) 
+        | (_, Tvar _) ->
             (* cases taken care of *)
             assert false
         | (Tarrow (l1, t1, u1, c1), Tarrow (l2, t2, u2, c2)) when l1 = l2
@@ -2214,8 +2212,9 @@
             (* Type [t2'] may have been instantiated by [unify_fields] *)
             (* XXX One should do some kind of unification... *)
             begin match (repr t2').desc with
-              Tobject (_, {contents = Some (_, va::_)})
-              when let va = repr va in List.mem va.desc [Tvar; Tunivar; Tnil] ->
+              Tobject (_, {contents = Some (_, va::_)}) when
+	      (match (repr va).desc with
+		Tvar _|Tunivar _|Tnil -> true | _ -> false) ->
                 ()
             | Tobject (_, nm2) ->
                 set_name nm2 !nm1
@@ -2290,16 +2289,32 @@
     raise (Unify []);
   List.iter2 (unify env) tl1 tl2
 
+(* Build a fresh row variable for unification *)
+and make_rowvar level use1 rest1 use2 rest2  =
+  let set_name ty name =
+    match ty.desc with
+      Tvar None -> log_type ty; ty.desc <- Tvar name
+    | _ -> ()
+  in
+  let name =
+    match rest1.desc, rest2.desc with
+      Tvar (Some _ as name1), Tvar (Some _ as name2) ->
+        if rest1.level <= rest2.level then name1 else name2
+    | Tvar (Some _ as name), _ ->
+        if use2 then set_name rest2 name; name
+    | _, Tvar (Some _ as name) ->
+        if use1 then set_name rest2 name; name
+    | _ -> None
+  in
+  if use1 then rest1 else
+  if use2 then rest2 else newvar2 ?name level
+
 and unify_fields env ty1 ty2 =          (* Optimization *)
   let (fields1, rest1) = flatten_fields ty1
   and (fields2, rest2) = flatten_fields ty2 in
   let (pairs, miss1, miss2) = associate_fields fields1 fields2 in
   let l1 = (repr ty1).level and l2 = (repr ty2).level in
-  let va =
-    if miss1 = [] then rest2
-    else if miss2 = [] then rest1
-    else newty2 (min l1 l2) Tvar
-  in
+  let va = make_rowvar (min l1 l2) (miss2=[]) rest1 (miss1=[]) rest2 in
   let d1 = rest1.desc and d2 = rest2.desc in
   try
     unify env (build_fields l1 miss1 va) rest2;
@@ -2390,7 +2405,7 @@
     let rm = row_more row in
     if row.row_fixed then
       if row0.row_more == rm then () else
-      if rm.desc = Tvar then link_type rm row0.row_more else
+      if is_Tvar rm then link_type rm row0.row_more else
       unify env rm row0.row_more
     else
       let ty = newty2 generic_level (Tvariant {row0 with row_fields = rest}) in
@@ -2489,7 +2504,7 @@
   let t1 = repr t1 and t2 = repr t2 in
   if t1 == t2 then () else
   match t1.desc with
-    Tvar ->
+    Tvar _ ->
       begin try
         occur env t1 t2;
         update_level env t1.level t2;
@@ -2527,7 +2542,7 @@
 let rec filter_arrow env t l =
   let t = expand_head_unif env t in
   match t.desc with
-    Tvar ->
+    Tvar _ ->
       let lv = t.level in
       let t1 = newvar2 lv and t2 = newvar2 lv in
       let t' = newty2 lv (Tarrow (l, t1, t2, Cok)) in
@@ -2543,7 +2558,7 @@
 let rec filter_method_field env name priv ty =
   let ty = repr ty in
   match ty.desc with
-    Tvar ->
+    Tvar _ ->
       let level = ty.level in
       let ty1 = newvar2 level and ty2 = newvar2 level in
       let ty' = newty2 level (Tfield (name,
@@ -2570,7 +2585,7 @@
 let rec filter_method env name priv ty =
   let ty = expand_head_unif env ty in
   match ty.desc with
-    Tvar ->
+    Tvar _ ->
       let ty1 = newvar () in
       let ty' = newobj ty1 in
       update_level env ty.level ty';
@@ -2606,7 +2621,7 @@
   let rec occur ty =
     let ty = repr ty in
     if ty.level > level then begin
-      if ty.desc = Tvar && ty.level >= generic_level - 1 then raise Occur;
+      if is_Tvar ty && ty.level >= generic_level - 1 then raise Occur;
       ty.level <- pivot_level - ty.level;
       match ty.desc with
         Tvariant row when static_row row ->
@@ -2636,7 +2651,7 @@
 
   try
     match (t1.desc, t2.desc) with
-      (Tvar, _) when may_instantiate inst_nongen t1 ->
+      (Tvar _, _) when may_instantiate inst_nongen t1 ->
         moregen_occur env t1.level t2;
         occur env t1 t2;
         link_type t1 t2
@@ -2653,7 +2668,7 @@
         with Not_found ->
           TypePairs.add type_pairs (t1', t2') ();
           match (t1'.desc, t2'.desc) with
-            (Tvar, _) when may_instantiate inst_nongen t1' ->
+            (Tvar _, _) when may_instantiate inst_nongen t1' ->
               moregen_occur env t1'.level t2;
               link_type t1' t2
           | (Tarrow (l1, t1, u1, _), Tarrow (l2, t2, u2, _)) when l1 = l2
@@ -2684,7 +2699,7 @@
           | (Tpoly (t1, tl1), Tpoly (t2, tl2)) ->
               enter_poly env univar_pairs t1 tl1 t2 tl2
                 (moregen inst_nongen type_pairs env)
-          | (Tunivar, Tunivar) ->
+          | (Tunivar _, Tunivar _) ->
               unify_univar t1' t2' !univar_pairs
           | (_, _) ->
               raise (Unify [])
@@ -2725,7 +2740,7 @@
   let row1 = row_repr row1 and row2 = row_repr row2 in
   let rm1 = repr row1.row_more and rm2 = repr row2.row_more in
   if rm1 == rm2 then () else
-  let may_inst = rm1.desc = Tvar && may_instantiate inst_nongen rm1 in
+  let may_inst = is_Tvar rm1 && may_instantiate inst_nongen rm1 in
   let r1, r2, pairs = merge_row_fields row1.row_fields row2.row_fields in
   let r1, r2 =
     if row2.row_closed then
@@ -2735,9 +2750,9 @@
   if r1 <> [] || row1.row_closed && (not row2.row_closed || r2 <> [])
   then raise (Unify []);
   begin match rm1.desc, rm2.desc with
-    Tunivar, Tunivar ->
+    Tunivar _, Tunivar _ ->
       unify_univar rm1 rm2 !univar_pairs
-  | Tunivar, _ | _, Tunivar ->
+  | Tunivar _, _ | _, Tunivar _ ->
       raise (Unify [])
   | _ when static_row row1 -> ()
   | _ when may_inst ->
@@ -2828,13 +2843,13 @@
   if ty.level >= lowest_level then begin
     ty.level <- pivot_level - ty.level;
     match ty.desc with
-    | Tvar ->
+    | Tvar _ ->
         if not (List.memq ty !vars) then vars := ty :: !vars
     | Tvariant row ->
         let row = row_repr row in
         let more = repr row.row_more in
-        if more.desc = Tvar && not row.row_fixed then begin
-          let more' = newty2 more.level Tvar in
+        if is_Tvar more && not row.row_fixed then begin
+          let more' = newty2 more.level more.desc in
           let row' = {row with row_fixed=true; row_fields=[]; row_more=more'}
           in link_type more (newty2 ty.level (Tvariant row'))
         end;
@@ -2857,7 +2872,7 @@
     (fun ty ->
       let ty = expand_head env ty in
       if List.memq ty !tyl then false else
-      (tyl := ty :: !tyl; ty.desc = Tvar))
+      (tyl := ty :: !tyl; is_Tvar ty))
     vars
 
 let matches env ty ty' =
@@ -2901,7 +2916,7 @@
 
   try
     match (t1.desc, t2.desc) with
-      (Tvar, Tvar) when rename ->
+      (Tvar _, Tvar _) when rename ->
         begin try
           normalize_subst subst;
           if List.assq t1 !subst != t2 then raise (Unify [])
@@ -2922,7 +2937,7 @@
         with Not_found ->
           TypePairs.add type_pairs (t1', t2') ();
           match (t1'.desc, t2'.desc) with
-            (Tvar, Tvar) when rename ->
+            (Tvar _, Tvar _) when rename ->
               begin try
                 normalize_subst subst;
                 if List.assq t1' !subst != t2' then raise (Unify [])
@@ -2956,7 +2971,7 @@
           | (Tpoly (t1, tl1), Tpoly (t2, tl2)) ->
               enter_poly env univar_pairs t1 tl1 t2 tl2
                 (eqtype rename type_pairs subst env)
-          | (Tunivar, Tunivar) ->
+          | (Tunivar _, Tunivar _) ->
               unify_univar t1' t2' !univar_pairs
           | (_, _) ->
               raise (Unify [])
@@ -3405,7 +3420,7 @@
 let rec build_subtype env visited loops posi level t =
   let t = repr t in
   match t.desc with
-    Tvar ->
+    Tvar _ ->
       if posi then
         try
           let t' = List.assq t loops in
@@ -3454,13 +3469,13 @@
              as this occurence might break the occur check.
              XXX not clear whether this correct anyway... *)
           if List.exists (deep_occur ty) tl1 then raise Not_found;
-          ty.desc <- Tvar;
+          ty.desc <- Tvar None;
           let t'' = newvar () in
           let loops = (ty, t'') :: loops in
           (* May discard [visited] as level is going down *)
           let (ty1', c) =
             build_subtype env [t'] loops posi (pred_enlarge level') ty1 in
-          assert (t''.desc = Tvar);
+          assert (is_Tvar t'');
           let nm =
             if c > Equiv || deep_occur ty ty1' then None else Some(p,tl1) in
           t''.desc <- Tobject (ty1', ref nm);
@@ -3559,7 +3574,7 @@
       let (t1', c) = build_subtype env visited loops posi level t1 in
       if c > Unchanged then (newty (Tpoly(t1', tl)), c)
       else (t, Unchanged)
-  | Tunivar | Tpackage _ ->
+  | Tunivar _ | Tpackage _ ->
       (t, Unchanged)
 
 let enlarge_type env ty =
@@ -3623,7 +3638,7 @@
   with Not_found ->
     TypePairs.add subtypes (t1, t2) ();
     match (t1.desc, t2.desc) with
-      (Tvar, _) | (_, Tvar) ->
+      (Tvar _, _) | (_, Tvar _) ->
         (trace, t1, t2, !univar_pairs)::cstrs
     | (Tarrow(l1, t1, u1, _), Tarrow(l2, t2, u2, _)) when l1 = l2
       || !Clflags.classic && not (is_optional l1 || is_optional l2) ->
@@ -3659,7 +3674,7 @@
     | (Tconstr(p1, tl1, _), _) when private_abbrev env p1 ->
         subtype_rec env trace (expand_abbrev_opt env t1) t2 cstrs
     | (Tobject (f1, _), Tobject (f2, _))
-      when (object_row f1).desc = Tvar && (object_row f2).desc = Tvar ->
+      when is_Tvar (object_row f1) && is_Tvar (object_row f2) ->
         (* Same row variable implies same object. *)
         (trace, t1, t2, !univar_pairs)::cstrs
     | (Tobject (f1, _), Tobject (f2, _)) ->
@@ -3731,7 +3746,7 @@
   match more1.desc, more2.desc with
     Tconstr(p1,_,_), Tconstr(p2,_,_) when Path.same p1 p2 ->
       subtype_rec env ((more1,more2)::trace) more1 more2 cstrs
-  | (Tvar|Tconstr _), (Tvar|Tconstr _)
+  | (Tvar _|Tconstr _), (Tvar _|Tconstr _)
     when row1.row_closed && r1 = [] ->
       List.fold_left
         (fun cstrs (_,f1,f2) ->
@@ -3745,7 +3760,7 @@
           | Rabsent, _ -> cstrs
           | _ -> raise Exit)
         cstrs pairs
-  | Tunivar, Tunivar
+  | Tunivar _, Tunivar _
     when row1.row_closed = row2.row_closed && r1 = [] && r2 = [] ->
       let cstrs =
         subtype_rec env ((more1,more2)::trace) more1 more2 cstrs in
@@ -3789,19 +3804,19 @@
   match ty.desc with
     Tfield (s, k, t1, t2) ->
       newty2 ty.level (Tfield (s, k, t1, unalias_object t2))
-  | Tvar | Tnil ->
+  | Tvar _ | Tnil ->
       newty2 ty.level ty.desc
-  | Tunivar ->
+  | Tunivar _ ->
       ty
   | Tconstr _ ->
-      newty2 ty.level Tvar
+      newvar2 ty.level
   | _ ->
       assert false
 
 let unalias ty =
   let ty = repr ty in
   match ty.desc with
-    Tvar | Tunivar ->
+    Tvar _ | Tunivar _ ->
       ty
   | Tvariant row ->
       let row = row_repr row in
@@ -3875,7 +3890,7 @@
               set_name nm None
             else let v' = repr v in
             begin match v'.desc with
-            | Tvar|Tunivar ->
+            | Tvar _ | Tunivar _ ->
                 if v' != v then set_name nm (Some (n, v' :: l))
             | Tnil ->
                 log_type ty; ty.desc <- Tconstr (n, l, ref Mnil)
@@ -3917,7 +3932,7 @@
 
 let rec nondep_type_rec env id ty =
   match ty.desc with
-    Tvar | Tunivar -> ty
+    Tvar _ | Tunivar _ -> ty
   | Tlink ty -> nondep_type_rec env id ty
   | _ -> try TypeHash.find nondep_hash ty
   with Not_found ->
@@ -3987,7 +4002,7 @@
 
 let unroll_abbrev id tl ty =
   let ty = repr ty and path = Path.Pident id in
-  if (ty.desc = Tvar) || (List.exists (deep_occur ty) tl)
+  if is_Tvar ty || (List.exists (deep_occur ty) tl)
   || is_object_type path then
     ty
   else
Index: typing/printtyp.ml
===================================================================
--- typing/printtyp.ml	(リビジョン 11207)
+++ typing/printtyp.ml	(作業コピー)
@@ -109,6 +109,10 @@
   | Mcons (priv, p, t1, t2, rem) -> p :: list_of_memo rem
   | Mlink rem -> list_of_memo !rem
 
+let print_name ppf = function
+    None -> fprintf ppf "None"
+  | Some name -> fprintf ppf "\"%s\"" name
+
 let visited = ref []
 let rec raw_type ppf ty =
   let ty = safe_repr [] ty in
@@ -119,7 +123,7 @@
   end
 and raw_type_list tl = raw_list raw_type tl
 and raw_type_desc ppf = function
-    Tvar -> fprintf ppf "Tvar"
+    Tvar name -> fprintf ppf "Tvar %a" print_name name
   | Tarrow(l,t1,t2,c) ->
       fprintf ppf "@[<hov1>Tarrow(%s,@,%a,@,%a,@,%s)@]"
         l raw_type t1 raw_type t2
@@ -143,7 +147,7 @@
   | Tnil -> fprintf ppf "Tnil"
   | Tlink t -> fprintf ppf "@[<1>Tlink@,%a@]" raw_type t
   | Tsubst t -> fprintf ppf "@[<1>Tsubst@,%a@]" raw_type t
-  | Tunivar -> fprintf ppf "Tunivar"
+  | Tunivar name -> fprintf ppf "Tunivar %a" print_name name
   | Tpoly (t, tl) ->
       fprintf ppf "@[<hov1>Tpoly(@,%a,@,%a)@]"
         raw_type t
@@ -189,28 +193,61 @@
 
 let names = ref ([] : (type_expr * string) list)
 let name_counter = ref 0
+let named_vars = ref ([] : string list)
 
-let reset_names () = names := []; name_counter := 0
+let reset_names () = names := []; name_counter := 0; named_vars := []
+let add_named_var ty =
+  match ty.desc with
+    Tvar (Some name) | Tunivar (Some name) ->
+      if List.mem name !named_vars then () else
+      named_vars := name :: !named_vars
+  | _ -> ()
 
-let new_name () =
+let rec new_name () =
   let name =
     if !name_counter < 26
     then String.make 1 (Char.chr(97 + !name_counter))
     else String.make 1 (Char.chr(97 + !name_counter mod 26)) ^
            string_of_int(!name_counter / 26) in
   incr name_counter;
-  name
+  if List.mem name !named_vars
+  || List.exists (fun (_, name') -> name = name') !names
+  then new_name ()
+  else name
 
 let name_of_type t =
+  (* We've already been through repr at this stage, so t is our representative
+     of the union-find class. *)
   try List.assq t !names with Not_found ->
-    let name = new_name () in
+    let name =
+      match t.desc with
+        Tvar (Some name) | Tunivar (Some name) ->
+          (* Some part of the type we've already printed has assigned another
+           * unification variable to that name. We want to keep the name, so try
+           * adding a number until we find a name that's not taken. *)
+          let current_name = ref name in
+          let i = ref 0 in
+          while List.exists (fun (_, name') -> !current_name = name') !names do
+            current_name := name ^ (string_of_int !i);
+            i := !i + 1;
+          done;
+          !current_name
+      | _ ->
+          (* No name available, create a new one *)
+          new_name ()
+    in
     names := (t, name) :: !names;
     name
 
 let check_name_of_type t = ignore(name_of_type t)
 
+let remove_names tyl =
+  let tyl = List.map repr tyl in
+  names := List.filter (fun (ty,_) -> not (List.memq ty tyl)) !names
+
+
 let non_gen_mark sch ty =
-  if sch && ty.desc = Tvar && ty.level <> generic_level then "_" else ""
+  if sch && is_Tvar ty && ty.level <> generic_level then "_" else ""
 
 let print_name_of_type sch ppf t =
   fprintf ppf "'%s%s" (non_gen_mark sch t) (name_of_type t)
@@ -225,9 +262,13 @@
 let is_aliased ty = List.memq (proxy ty) !aliased
 let add_alias ty =
   let px = proxy ty in
-  if not (is_aliased px) then aliased := px :: !aliased
+  if not (is_aliased px) then begin
+    aliased := px :: !aliased;
+    add_named_var px
+  end
+
 let aliasable ty =
-  match ty.desc with Tvar | Tunivar | Tpoly _ -> false | _ -> true
+  match ty.desc with Tvar _ | Tunivar _ | Tpoly _ -> false | _ -> true
 
 let namable_row row =
   row.row_name <> None &&
@@ -245,7 +286,7 @@
   if List.memq px visited && aliasable ty then add_alias px else
     let visited = px :: visited in
     match ty.desc with
-    | Tvar -> ()
+    | Tvar _ -> add_named_var ty
     | Tarrow(_, ty1, ty2, _) ->
         mark_loops_rec visited ty1; mark_loops_rec visited ty2
     | Ttuple tyl -> List.iter (mark_loops_rec visited) tyl
@@ -290,7 +331,7 @@
     | Tpoly (ty, tyl) ->
         List.iter (fun t -> add_alias t) tyl;
         mark_loops_rec visited ty
-    | Tunivar -> ()
+    | Tunivar _ -> add_named_var ty
 
 let mark_loops ty =
   normalize_type Env.empty ty;
@@ -322,7 +363,7 @@
 
   let pr_typ () =
     match ty.desc with
-    | Tvar ->
+    | Tvar _ ->
         Otyp_var (is_non_gen sch ty, name_of_type ty)
     | Tarrow(l, ty1, ty2, _) ->
         let pr_arrow l ty1 ty2 =
@@ -387,16 +428,22 @@
     | Tpoly (ty, []) ->
         tree_of_typexp sch ty
     | Tpoly (ty, tyl) ->
+        (*let print_names () =
+          List.iter (fun (_, name) -> prerr_string (name ^ " ")) !names;
+          prerr_string "; " in *)
         let tyl = List.map repr tyl in
-        (* let tyl = List.filter is_aliased tyl in *)
         if tyl = [] then tree_of_typexp sch ty else begin
           let old_delayed = !delayed in
+          (* Make the names delayed, so that the real type is
+             printed once when used as proxy *)
           List.iter add_delayed tyl;
           let tl = List.map name_of_type tyl in
           let tr = Otyp_poly (tl, tree_of_typexp sch ty) in
+          (* Forget names when we leave scope *)
+          remove_names tyl;
           delayed := old_delayed; tr
         end
-    | Tunivar ->
+    | Tunivar _ ->
         Otyp_var (false, name_of_type ty)
     | Tpackage (p, n, tyl) ->
         Otyp_module (Path.name p, n, tree_of_typlist sch tyl)
@@ -446,13 +493,13 @@
   end
 
 and is_non_gen sch ty =
-    sch && ty.desc = Tvar && ty.level <> generic_level
+    sch && is_Tvar ty && ty.level <> generic_level
 
 and tree_of_typfields sch rest = function
   | [] ->
       let rest =
         match rest.desc with
-        | Tvar | Tunivar -> Some (is_non_gen sch rest)
+        | Tvar _ | Tunivar _ -> Some (is_non_gen sch rest)
         | Tconstr _ -> Some false
         | Tnil -> None
         | _ -> fatal_error "typfields (1)"
@@ -564,7 +611,7 @@
     let vari =
       List.map2
         (fun ty (co,cn,ct) ->
-          if abstr || (repr ty).desc <> Tvar then (co,cn) else (true,true))
+          if abstr || not (is_Tvar (repr ty)) then (co,cn) else (true,true))
         decl.type_params decl.type_variance
     in
     (Ident.name id,
@@ -645,16 +692,18 @@
 
 let method_type (_, kind, ty) =
   match field_kind_repr kind, repr ty with
-    Fpresent, {desc=Tpoly(ty, _)} -> ty
-  | _       , ty                  -> ty
+    Fpresent, {desc=Tpoly(ty, tyl)} -> (ty, tyl)
+  | _       , ty                    -> (ty, [])
 
 let tree_of_metho sch concrete csil (lab, kind, ty) =
   if lab <> dummy_method then begin
     let kind = field_kind_repr kind in
     let priv = kind <> Fpresent in
     let virt = not (Concr.mem lab concrete) in
-    let ty = method_type (lab, kind, ty) in
-    Ocsg_method (lab, priv, virt, tree_of_typexp sch ty) :: csil
+    let (ty, tyl) = method_type (lab, kind, ty) in
+    let tty = tree_of_typexp sch ty in
+    remove_names tyl;
+    Ocsg_method (lab, priv, virt, tty) :: csil
   end
   else csil
 
@@ -662,7 +711,7 @@
   | Tcty_constr (p, tyl, cty) ->
       let sty = Ctype.self_type cty in
       if List.memq (proxy sty) !visited_objects
-      || List.exists (fun ty -> (repr ty).desc <> Tvar) params
+      || not (List.for_all is_Tvar params)
       || List.exists (deep_occur sty) tyl
       then prepare_class_type params cty
       else List.iter mark_loops tyl
@@ -675,7 +724,7 @@
       let (fields, _) =
         Ctype.flatten_fields (Ctype.object_fields sign.cty_self)
       in
-      List.iter (fun met -> mark_loops (method_type met)) fields;
+      List.iter (fun met -> mark_loops (fst (method_type met))) fields;
       Vars.iter (fun _ (_, _, ty) -> mark_loops ty) sign.cty_vars
   | Tcty_fun (_, ty, cty) ->
       mark_loops ty;
@@ -686,7 +735,7 @@
   | Tcty_constr (p', tyl, cty) ->
       let sty = Ctype.self_type cty in
       if List.memq (proxy sty) !visited_objects
-      || List.exists (fun ty -> (repr ty).desc <> Tvar) params
+      || not (List.for_all is_Tvar params)
       then
         tree_of_class_type sch params cty
       else
@@ -743,7 +792,7 @@
   (match tree_of_typexp true param with
     Otyp_var (_, s) -> s
   | _ -> "?"),
-  if (repr param).desc = Tvar then (true, true) else variance
+  if is_Tvar (repr param) then (true, true) else variance
 
 let tree_of_class_params params =
   let tyl = tree_of_typlist true params in
@@ -890,7 +939,7 @@
   | {desc = Tvariant row} as t when (row_repr row).row_name <> None ->
       newty2 t.level
         (Tvariant {(row_repr row) with row_name = None;
-                   row_more = newty2 (row_more row).level Tvar})
+                   row_more = newvar2 (row_more row).level})
   | _ -> t
 
 let prepare_expansion (t, t') =
@@ -913,9 +962,9 @@
 let has_explanation unif t3 t4 =
   match t3.desc, t4.desc with
     Tfield _, _ | _, Tfield _
-  | Tunivar, Tvar | Tvar, Tunivar
+  | Tunivar _, Tvar _ | Tvar _, Tunivar _
   | Tvariant _, Tvariant _ -> true
-  | Tconstr (p, _, _), Tvar | Tvar, Tconstr (p, _, _) ->
+  | Tconstr (p, _, _), Tvar _ | Tvar _, Tconstr (p, _, _) ->
       unif && min t3.level t4.level < Path.binding_time p
   | _ -> false
 
@@ -931,21 +980,21 @@
 
 let explanation unif t3 t4 ppf =
   match t3.desc, t4.desc with
-  | Tfield _, Tvar | Tvar, Tfield _ ->
+  | Tfield _, Tvar _ | Tvar _, Tfield _ ->
       fprintf ppf "@,Self type cannot escape its class"
-  | Tconstr (p, tl, _), Tvar
+  | Tconstr (p, tl, _), Tvar _
     when unif && (tl = [] || t4.level < Path.binding_time p) ->
       fprintf ppf
         "@,@[The type constructor@;<1 2>%a@ would escape its scope@]"
         path p
-  | Tvar, Tconstr (p, tl, _)
+  | Tvar _, Tconstr (p, tl, _)
     when unif && (tl = [] || t3.level < Path.binding_time p) ->
       fprintf ppf
         "@,@[The type constructor@;<1 2>%a@ would escape its scope@]"
         path p
-  | Tvar, Tunivar | Tunivar, Tvar ->
+  | Tvar _, Tunivar _ | Tunivar _, Tvar _ ->
       fprintf ppf "@,The universal variable %a would escape its scope"
-        type_expr (if t3.desc = Tunivar then t3 else t4)
+        type_expr (if is_Tunivar t3 then t3 else t4)
   | Tfield (lab, _, _, _), _
   | _, Tfield (lab, _, _, _) when lab = dummy_method ->
       fprintf ppf
Index: typing/includecore.ml
===================================================================
--- typing/includecore.ml	(リビジョン 11207)
+++ typing/includecore.ml	(作業コピー)
@@ -61,7 +61,7 @@
     Tvariant row1, Tvariant row2 when is_absrow env (Btype.row_more row2) ->
       let row1 = Btype.row_repr row1 and row2 = Btype.row_repr row2 in
       Ctype.equal env true (ty1::params1) (row2.row_more::params2) &&
-      (match row1.row_more with {desc=Tvar|Tconstr _} -> true | _ -> false) &&
+      (match row1.row_more with {desc=Tvar _|Tconstr _} -> true | _ -> false) &&
       let r1, r2, pairs =
         Ctype.merge_row_fields row1.row_fields row2.row_fields in
       (not row2.row_closed ||
@@ -91,7 +91,7 @@
       let (fields2,rest2) = Ctype.flatten_fields fi2 in
       Ctype.equal env true (ty1::params1) (rest2::params2) &&
       let (fields1,rest1) = Ctype.flatten_fields fi1 in
-      (match rest1 with {desc=Tnil|Tvar|Tconstr _} -> true | _ -> false) &&
+      (match rest1 with {desc=Tnil|Tvar _|Tconstr _} -> true | _ -> false) &&
       let pairs, miss1, miss2 = Ctype.associate_fields fields1 fields2 in
       miss2 = [] &&
       let tl1, tl2 =
@@ -251,7 +251,7 @@
 let encode_val (mut, ty) rem =
   begin match mut with
     Asttypes.Mutable   -> Predef.type_unit
-  | Asttypes.Immutable -> Btype.newgenty Tvar
+  | Asttypes.Immutable -> Btype.newgenvar ()
   end
   ::ty::rem
 
Index: typing/subst.ml
===================================================================
--- typing/subst.ml	(リビジョン 11207)
+++ typing/subst.ml	(作業コピー)
@@ -71,16 +71,19 @@
 let reset_for_saving () = new_id := -1
 
 let newpersty desc =
-  decr new_id; { desc = desc; level = generic_level; id = !new_id }
+  decr new_id;
+  { desc = desc; level = generic_level; id = !new_id }
 
 (* Similar to [Ctype.nondep_type_rec]. *)
 let rec typexp s ty =
   let ty = repr ty in
   match ty.desc with
-    Tvar | Tunivar ->
+    Tvar _ | Tunivar _ ->
       if s.for_saving || ty.id < 0 then
+        let desc = match ty.desc with (* Tvar _ -> Tvar None *) | d -> d in
         let ty' =
-          if s.for_saving then newpersty ty.desc else newty2 ty.level ty.desc
+          if s.for_saving then newpersty desc
+          else newty2 ty.level desc
         in
         save_desc ty ty.desc; ty.desc <- Tsubst ty'; ty'
       else ty
@@ -94,7 +97,7 @@
     let desc = ty.desc in
     save_desc ty desc;
     (* Make a stub *)
-    let ty' = if s.for_saving then newpersty Tvar else newgenvar () in
+    let ty' = if s.for_saving then newpersty (Tvar None) else newgenvar () in
     ty.desc <- Tsubst ty';
     ty'.desc <-
       begin match desc with
@@ -127,10 +130,10 @@
                 match more.desc with
                   Tsubst ty -> ty
                 | Tconstr _ -> typexp s more
-                | Tunivar | Tvar ->
+                | Tunivar _ | Tvar _ ->
                     save_desc more more.desc;
                     if s.for_saving then newpersty more.desc else
-                    if dup && more.desc <> Tunivar then newgenvar () else more
+                    if dup && is_Tvar more then newgenty more.desc else more
                 | _ -> assert false
               in
               (* Register new type first for recursion *)
Index: typing/types.ml
===================================================================
--- typing/types.ml	(リビジョン 11207)
+++ typing/types.ml	(作業コピー)
@@ -25,7 +25,7 @@
     mutable id: int }
 
 and type_desc =
-    Tvar
+    Tvar of string option
   | Tarrow of label * type_expr * type_expr * commutable
   | Ttuple of type_expr list
   | Tconstr of Path.t * type_expr list * abbrev_memo ref
@@ -35,7 +35,7 @@
   | Tlink of type_expr
   | Tsubst of type_expr         (* for copying *)
   | Tvariant of row_desc
-  | Tunivar
+  | Tunivar of string option
   | Tpoly of type_expr * type_expr list
   | Tpackage of Path.t * string list * type_expr list
 
Index: ocamldoc/odoc_str.ml
===================================================================
--- ocamldoc/odoc_str.ml	(リビジョン 11207)
+++ ocamldoc/odoc_str.ml	(作業コピー)
@@ -31,7 +31,7 @@
   | Types.Tlink t2 | Types.Tsubst t2 -> is_arrow_type t2
   | Types.Ttuple _
   | Types.Tconstr _
-  | Types.Tvar | Types.Tunivar | Types.Tobject _ | Types.Tpoly _
+  | Types.Tvar _ | Types.Tunivar _ | Types.Tobject _ | Types.Tpoly _
   | Types.Tfield _ | Types.Tnil | Types.Tvariant _ | Types.Tpackage _ -> false
 
 let raw_string_of_type_list sep type_list =
@@ -43,7 +43,7 @@
     | Types.Tlink t2 | Types.Tsubst t2 -> need_parent t2
     | Types.Tconstr _ ->
         false
-    | Types.Tvar | Types.Tunivar | Types.Tobject _ | Types.Tpoly _
+    | Types.Tvar _ | Types.Tunivar _ | Types.Tobject _ | Types.Tpoly _
     | Types.Tfield _ | Types.Tnil | Types.Tvariant _ | Types.Tpackage _ -> false
   in
   let print_one_type variance t =
Index: ocamldoc/odoc_value.ml
===================================================================
--- ocamldoc/odoc_value.ml	(リビジョン 11207)
+++ ocamldoc/odoc_value.ml	(作業コピー)
@@ -77,13 +77,13 @@
     | Types.Tsubst texp ->
         iter texp
     | Types.Tpoly (texp, _) -> iter texp
-    | Types.Tvar
+    | Types.Tvar _
     | Types.Ttuple _
     | Types.Tconstr _
     | Types.Tobject _
     | Types.Tfield _
     | Types.Tnil
-    | Types.Tunivar
+    | Types.Tunivar _
     | Types.Tpackage _
     | Types.Tvariant _ ->
         []
Index: ocamldoc/odoc_misc.ml
===================================================================
--- ocamldoc/odoc_misc.ml	(リビジョン 11207)
+++ ocamldoc/odoc_misc.ml	(作業コピー)
@@ -478,8 +478,8 @@
     match t with
     | Types.Tconstr(path, [ty], _) when Path.same path Predef.path_option -> ty.Types.desc
     | Types.Tconstr _
-    | Types.Tvar
-    | Types.Tunivar
+    | Types.Tvar _
+    | Types.Tunivar _
     | Types.Tpoly _
     | Types.Tarrow _
     | Types.Ttuple _
Index: bytecomp/typeopt.ml
===================================================================
--- bytecomp/typeopt.ml	(リビジョン 11207)
+++ bytecomp/typeopt.ml	(作業コピー)
@@ -50,7 +50,7 @@
 
 let array_element_kind env ty =
   match scrape env ty with
-  | Tvar | Tunivar ->
+  | Tvar _ | Tunivar _ ->
       Pgenarray
   | Tconstr(p, args, abbrev) ->
       if Path.same p Predef.path_int || Path.same p Predef.path_char then
Index: bytecomp/translcore.ml
===================================================================
--- bytecomp/translcore.ml	(リビジョン 11207)
+++ bytecomp/translcore.ml	(作業コピー)
@@ -780,12 +780,13 @@
           begin match e.exp_type.desc with
           (* the following may represent a float/forward/lazy: need a
              forward_tag *)
-          | Tvar | Tlink _ | Tsubst _ | Tunivar
+          | Tvar _ | Tlink _ | Tsubst _ | Tunivar _
           | Tpoly(_,_) | Tfield(_,_,_,_) ->
               Lprim(Pmakeblock(Obj.forward_tag, Immutable), [transl_exp e])
           (* the following cannot be represented as float/forward/lazy:
              optimize *)
-          | Tarrow(_,_,_,_) | Ttuple _ | Tpackage _ | Tobject(_,_) | Tnil | Tvariant _
+          | Tarrow(_,_,_,_) | Ttuple _ | Tpackage _ | Tobject(_,_) | Tnil
+          | Tvariant _
               -> transl_exp e
           (* optimize predefined types (excepted float) *)
           | Tconstr(_,_,_) ->
Index: testsuite/tests/lib-hashtbl/htbl.ml
===================================================================
--- testsuite/tests/lib-hashtbl/htbl.ml	(リビジョン 11207)
+++ testsuite/tests/lib-hashtbl/htbl.ml	(作業コピー)
@@ -76,7 +76,7 @@
   struct
     type key = M.key
     type 'a t = (key, 'a) Hashtbl.t
-    let create = Hashtbl.create
+    let create s = Hashtbl.create s
     let clear = Hashtbl.clear
     let copy = Hashtbl.copy
     let add = Hashtbl.add
Index: toplevel/genprintval.ml
===================================================================
--- toplevel/genprintval.ml	(リビジョン 11207)
+++ toplevel/genprintval.ml	(作業コピー)
@@ -180,7 +180,7 @@
           find_printer env ty obj
         with Not_found ->
           match (Ctype.repr ty).desc with
-          | Tvar ->
+          | Tvar _ | Tunivar _ ->
               Oval_stuff "<poly>"
           | Tarrow(_, ty1, ty2, _) ->
               Oval_stuff "<fun>"
@@ -327,8 +327,6 @@
               fatal_error "Printval.outval_of_value"
           | Tpoly (ty, _) ->
               tree_of_val (depth - 1) obj ty
-          | Tunivar ->
-              Oval_stuff "<poly>"
           | Tpackage _ ->
               Oval_stuff "<module>"
         end
Index: otherlibs/labltk/browser/searchid.ml
===================================================================
--- otherlibs/labltk/browser/searchid.ml	(リビジョン 11207)
+++ otherlibs/labltk/browser/searchid.ml	(作業コピー)
@@ -101,7 +101,7 @@
 
 let rec equal ~prefix t1 t2 =
   match (repr t1).desc, (repr t2).desc with
-    Tvar, Tvar -> true
+    Tvar _, Tvar _ -> true
   | Tvariant row1, Tvariant row2 ->
       let row1 = row_repr row1 and row2 = row_repr row2 in
       let fields1 = filter_row_fields false row1.row_fields
@@ -144,7 +144,7 @@
 
 let rec included ~prefix t1 t2 =
   match (repr t1).desc, (repr t2).desc with
-    Tvar, _ -> true
+    Tvar _, _ -> true
   | Tvariant row1, Tvariant row2 ->
       let row1 = row_repr row1 and row2 = row_repr row2 in
       let fields1 = filter_row_fields false row1.row_fields