Remove commented code in clean_type. Restore cleaning of variables that are in...

Remove commented code in clean_type. Restore cleaning of variables that are in covariant position in the result type, to avoid having strange types such as: [] -> [ ('b) * ]

types/types.ml

@@ -2804,7 +2804,7 @@ module Positive = struct
         let () = Memo.add memo (pos,v) () in
         match v.def with
         |`Type d -> ()
-        |`Variable d when Var.Set.mem d delta || not (Var.is_internal d) -> Hashtbl.replace vars d v
+        |`Variable d when Var.Set.mem d delta || (not (Var.is_internal d) && not pos) -> Hashtbl.replace vars d v
         |`Variable d ->
           begin try
             let td = Hashtbl.find vars d in
@@ -2840,22 +2840,6 @@ module Positive = struct
   let clean_type delta t =
     if no_var t then t else
       clean_variables delta t
-      (*let arrow_t, non_arrow_t =
-        { empty with arrow = t.arrow },
-        { t with arrow = empty.arrow }
-      in
-      let _, u_arrow = Arrow.get arrow_t in
-      let res = List.fold_left (fun acc i_arrow ->
-        T.cup acc (
-          let conj_arrow =
-            List.fold_left (fun acc (dom, cdom) ->
-              let indiv_arrow = T.arrow (T.cons dom) (T.cons cdom) in
-              DescrSList.add indiv_arrow acc
-            ) DescrSList.empty i_arrow
-          in
-          DescrSList.fold (T.cap) T.any conj_arrow
-        )
-        ) non_arrow_t u_arrow *)
 
 
 end