diff -r 397b59b4697c VERSION
--- a/VERSION	Wed Jun 17 13:12:31 2009 +0900
+++ b/VERSION	Mon Aug 31 03:55:04 2009 +0900
@@ -1,4 +1,4 @@
-3.11.1
+3.11.1+OCM-patch
 
 # The version string is the first line of this file.
 # It must be in the format described in stdlib/sys.mli
diff -r 397b59b4697c bytecomp/translcore.ml
--- a/bytecomp/translcore.ml	Wed Jun 17 13:12:31 2009 +0900
+++ b/bytecomp/translcore.ml	Mon Aug 31 03:55:04 2009 +0900
@@ -583,6 +583,39 @@
       raise(Error(e.exp_loc, Free_super_var))
   | Texp_ident(path, {val_kind = Val_reg | Val_self _}) ->
       transl_path path
+  | Texp_super_plus ->
+      let ty = 
+	match (Ctype.repr e.exp_type).desc with
+	| Tarrow (_, ty, _, _) -> Ctype.repr ty
+	| _ -> assert false
+      in
+      let ty = Ctype.expand_head e.exp_env ty in
+      let prim = 
+        match ty.desc with
+        | Tlink _ -> assert false
+        | Tvar -> fatal_error "(+)'s type is not instantiated"
+        | Tconstr (p, [], _) when Predef.path_int = p ->
+            (* copied from primitive.ml *)
+            { Primitive.prim_name = "%addint";
+              prim_arity = 2;
+              prim_alloc = true;
+              prim_native_name = "";
+              prim_native_float = false }
+        | Tconstr (p, [], _) when Predef.path_float = p -> 
+            { Primitive.prim_name = "%addfloat";
+              prim_arity = 2;
+              prim_alloc = true;
+              prim_native_name = "";
+              prim_native_float = false }
+        | _ -> 
+            (* This cannot happen since we have already checked the
+               instantiation at Typecore.Weak_variable.check () *)
+	    Format.eprintf "ERROR AT %a (type=%a)@." 
+	      Location.print_error e.exp_loc
+	      Printtyp.type_expr ty;
+	    fatal_error "(+)'s type must be int or float"
+      in
+      transl_primitive prim
   | Texp_ident _ -> fatal_error "Translcore.transl_exp: bad Texp_ident"
   | Texp_constant cst ->
       Lconst(Const_base cst)
diff -r 397b59b4697c otherlibs/labltk/browser/searchpos.ml
--- a/otherlibs/labltk/browser/searchpos.ml	Wed Jun 17 13:12:31 2009 +0900
+++ b/otherlibs/labltk/browser/searchpos.ml	Mon Aug 31 03:55:04 2009 +0900
@@ -733,6 +733,7 @@
     Texp_ident (path, _) ->
       add_found_str (`Exp(`Val path, exp.exp_type))
         ~env:exp.exp_env ~loc:exp.exp_loc
+  | Texp_super_plus -> assert false (* Skipped for excersize *)
   | Texp_constant v ->
       add_found_str (`Exp(`Const, exp.exp_type))
         ~env:exp.exp_env ~loc:exp.exp_loc
diff -r 397b59b4697c parsing/parser.mly
--- a/parsing/parser.mly	Wed Jun 17 13:12:31 2009 +0900
+++ b/parsing/parser.mly	Mon Aug 31 03:55:04 2009 +0900
@@ -45,7 +45,10 @@
 let reloc_exp x = { x with pexp_loc = symbol_rloc () };;
 
 let mkoperator name pos =
-  { pexp_desc = Pexp_ident(Lident name); pexp_loc = rhs_loc pos }
+  if name = "+" then
+    { pexp_desc = Pexp_super_plus; pexp_loc = rhs_loc pos }
+  else 
+    { pexp_desc = Pexp_ident(Lident name); pexp_loc = rhs_loc pos }
 
 (*
   Ghost expressions and patterns:
diff -r 397b59b4697c parsing/parsetree.mli
--- a/parsing/parsetree.mli	Wed Jun 17 13:12:31 2009 +0900
+++ b/parsing/parsetree.mli	Mon Aug 31 03:55:04 2009 +0900
@@ -112,6 +112,7 @@
   | Pexp_lazy of expression
   | Pexp_poly of expression * core_type option
   | Pexp_object of class_structure
+  | Pexp_super_plus
 
 (* Value descriptions *)
 
diff -r 397b59b4697c parsing/printast.ml
--- a/parsing/printast.ml	Wed Jun 17 13:12:31 2009 +0900
+++ b/parsing/printast.ml	Mon Aug 31 03:55:04 2009 +0900
@@ -202,6 +202,7 @@
   let i = i+1 in
   match x.pexp_desc with
   | Pexp_ident (li) -> line i ppf "Pexp_ident %a\n" fmt_longident li;
+  | Pexp_super_plus -> line i ppf "Pexp_super_plus\n";
   | Pexp_constant (c) -> line i ppf "Pexp_constant %a\n" fmt_constant c;
   | Pexp_let (rf, l, e) ->
       line i ppf "Pexp_let %a\n" fmt_rec_flag rf;
diff -r 397b59b4697c tools/depend.ml
--- a/tools/depend.ml	Wed Jun 17 13:12:31 2009 +0900
+++ b/tools/depend.ml	Mon Aug 31 03:55:04 2009 +0900
@@ -117,6 +117,7 @@
 let rec add_expr bv exp =
   match exp.pexp_desc with
     Pexp_ident l -> add bv l
+  | Pexp_super_plus -> ()
   | Pexp_constant _ -> ()
   | Pexp_let(_, pel, e) -> add_pat_expr_list bv pel; add_expr bv e
   | Pexp_function (_, opte, pel) ->
diff -r 397b59b4697c tools/ocamlprof.ml
--- a/tools/ocamlprof.ml	Wed Jun 17 13:12:31 2009 +0900
+++ b/tools/ocamlprof.ml	Mon Aug 31 03:55:04 2009 +0900
@@ -171,6 +171,7 @@
 and rw_exp iflag sexp =
   match sexp.pexp_desc with
     Pexp_ident lid -> ()
+  | Pexp_super_plus -> ()
   | Pexp_constant cst -> ()
 
   | Pexp_let(_, spat_sexp_list, sbody) ->
diff -r 397b59b4697c typing/ctype.ml
--- a/typing/ctype.ml	Wed Jun 17 13:12:31 2009 +0900
+++ b/typing/ctype.ml	Mon Aug 31 03:55:04 2009 +0900
@@ -97,9 +97,11 @@
 
 (**** Type level management ****)
 
-let current_level = ref 0
-let nongen_level = ref 0
-let global_level = ref 1
+(* Btype.lowest_level (=0) now has a special meaning as weak variables
+   and therefore the initial level must not be lowest_level. *)
+let current_level = ref 1
+let nongen_level = ref 1 (* init: equal to current_level *)
+let global_level = ref 2 (* init: current_level + 1 *)
 let saved_level = ref []
 
 let init_def level = current_level := level; nongen_level := level
@@ -607,7 +609,11 @@
   let ty = repr ty in
   if ty.level > level then begin
     begin match ty.desc with
-      Tconstr(p, tl, abbrev)  when level < Path.binding_time p ->
+    | Tconstr(p, tl, abbrev)  when level = Btype.lowest_level -> 
+        (* We avoid lower the level of Tconstr type to lowest,
+           since it causes the "escape the scope" error. *)
+        ()
+    | Tconstr(p, tl, abbrev)  when level < Path.binding_time p ->
         (* Try first to replace an abbreviation by its expansion. *)
         begin try
           link_type ty (!forward_try_expand_once env ty);
diff -r 397b59b4697c typing/typecore.ml
--- a/typing/typecore.ml	Wed Jun 17 13:12:31 2009 +0900
+++ b/typing/typecore.ml	Mon Aug 31 03:55:04 2009 +0900
@@ -60,6 +60,7 @@
   | Not_a_variant_type of Longident.t
   | Incoherent_label_order
   | Less_general of string * (type_expr * type_expr) list
+  | Super_plus_illegal_instance of type_expr
 
 exception Error of Location.t * error
 
@@ -90,6 +91,26 @@
   node
 ;;
 
+module Weak_variable = struct
+  let var_exps = ref []
+  let add var exp = var_exps := (var,exp) :: !var_exps
+  let check () =
+    List.iter (fun (var, e) ->
+      let ty = Ctype.expand_head e.exp_env var in
+      match ty.desc with
+      | Tlink _ -> assert false
+      | Tvar -> 
+	  (* defaulting to int *)
+	  unify e.exp_env ty (instance Predef.type_int)
+      | Tconstr (p, [], _) 
+	  when p = Predef.path_int || p = Predef.path_float -> 
+	  ()
+      | _ -> 
+	  raise (Error (e.exp_loc, 
+		       Super_plus_illegal_instance ty))
+    ) !var_exps;
+    var_exps := []
+end
 
 (* Typing of constants *)
 
@@ -602,6 +623,7 @@
 let reset_delayed_checks () = delayed_checks := []
 let add_delayed_check f = delayed_checks := f :: !delayed_checks
 let force_delayed_checks () =
+  Weak_variable.check();
   (* checks may change type levels *)
   let snap = Btype.snapshot () in
   List.iter (fun f -> f ()) (List.rev !delayed_checks);
@@ -930,7 +952,39 @@
 
 let rec type_exp env sexp =
   match sexp.pexp_desc with
-    Pexp_ident lid ->
+  | Pexp_super_plus ->
+      (* type of super plus is 'a -> 'a -> 'a 
+  	 where 
+  	 - 'a is fresh 
+  	 - 'a cannot be generalized
+      *)
+      let tvar = Btype.newty2 Btype.lowest_level Tvar in
+      let typ = 
+  	(* lowest_level <= !current_level, therefore variables with
+  	   lowest_level cannot be generalized 
+  	   
+  	   But lowest_level is too low. The level of the variable
+  	   should be same or larger than Path.binding_time <int/float>
+	   Otherwise the type system complains about escaping
+  	   int/float from their scopes.
+
+           Therefore, we have to change the meaning of lowest_level a
+           little bit. See ctype.ml, update_level.
+  	*)
+  	  Ctype.newty (Tarrow ("", 
+  			      tvar,
+  			      Ctype.newty (Tarrow("", tvar, tvar, Cok)),
+  			      Cok))
+        in
+        let exp = 
+	  { exp_desc = Texp_super_plus;
+  	    exp_loc = sexp.pexp_loc;
+  	    exp_type = typ;
+  	    exp_env = env }
+	in
+	Weak_variable.add tvar exp; 
+	re exp
+  | Pexp_ident lid ->
       begin try
         if !Clflags.annotations then begin
           try let (path, annot) = Env.lookup_annot lid env in
@@ -2247,3 +2301,5 @@
       report_unification_error ppf trace
         (fun ppf -> fprintf ppf "This %s has type" kind)
         (fun ppf -> fprintf ppf "which is less general than")
+  | Super_plus_illegal_instance ty ->
+      fprintf ppf "Super (+) cannot be used for type %a" type_expr ty
diff -r 397b59b4697c typing/typecore.mli
--- a/typing/typecore.mli	Wed Jun 17 13:12:31 2009 +0900
+++ b/typing/typecore.mli	Mon Aug 31 03:55:04 2009 +0900
@@ -100,6 +100,7 @@
   | Not_a_variant_type of Longident.t
   | Incoherent_label_order
   | Less_general of string * (type_expr * type_expr) list
+  | Super_plus_illegal_instance of type_expr
 
 exception Error of Location.t * error
 
diff -r 397b59b4697c typing/typedtree.ml
--- a/typing/typedtree.ml	Wed Jun 17 13:12:31 2009 +0900
+++ b/typing/typedtree.ml	Mon Aug 31 03:55:04 2009 +0900
@@ -79,6 +79,7 @@
   | Texp_assertfalse
   | Texp_lazy of expression
   | Texp_object of class_structure * class_signature * string list
+  | Texp_super_plus
 
 and meth =
     Tmeth_name of string
diff -r 397b59b4697c typing/typedtree.mli
--- a/typing/typedtree.mli	Wed Jun 17 13:12:31 2009 +0900
+++ b/typing/typedtree.mli	Mon Aug 31 03:55:04 2009 +0900
@@ -78,6 +78,7 @@
   | Texp_assertfalse
   | Texp_lazy of expression
   | Texp_object of class_structure * class_signature * string list
+  | Texp_super_plus
 
 and meth =
     Tmeth_name of string
diff -r 397b59b4697c typing/unused_var.ml
--- a/typing/unused_var.ml	Wed Jun 17 13:12:31 2009 +0900
+++ b/typing/unused_var.ml	Mon Aug 31 03:55:04 2009 +0900
@@ -113,6 +113,7 @@
       begin try (Hashtbl.find tbl id) := true;
       with Not_found -> ()
       end;
+  | Pexp_super_plus -> ()
   | Pexp_ident _ -> ()
   | Pexp_constant _ -> ()
   | Pexp_let (recflag, pel, e) ->