Handling field names that should not be displayed in counterexamples.

Do not append '.' to the name of the variable representing field access
if the field name is empty string (that is, if the field name should be
ignored in counterexample).

src/transform/eval_match.ml

@@ -66,7 +66,7 @@ let rec add_quant kn (vl,tl,f) v =
         let s = ty_match Mtv.empty (Opt.get ls.ls_value) ty in
         let mk_v ty pj =
 	  (* The name of the field corresponding to the variable that is created  *)
-	  let field_name = begin match pj with
+	  let field_name = (match pj with
 	    | Some pj_ls ->
 	      begin
 		try
@@ -74,17 +74,22 @@ let rec add_quant kn (vl,tl,f) v =
 		with Not_found -> pj_ls.ls_name.id_string
 	      end
 	    | _ -> ""
-	  end in
+	  ) in
+	  let field_str = if field_name <> "" then "." ^ field_name
+	    else "" in
 	  let label = Ident.append_to_model_element_name
-	    ~labels:v.vs_name.id_label ~to_append:("." ^ field_name) in
+	    ~labels:v.vs_name.id_label ~to_append:(field_str) in
 	  create_vsymbol (id_lab label v.vs_name) (ty_inst s ty) in
 
         let nvl = List.map2 mk_v ls.ls_args pjl in
         let t = fs_app ls (List.map t_var nvl) ty in
         let f = t_let_close_simp v t f in
         let tl = tr_map (t_subst_single v t) tl in
+        (* in case any of the fields is also a record, we recurse over the new
+           variables. *)
         List.fold_left (add_quant kn) (vl,tl,f) nvl
     | _ ->
+        (* zero or more than one constructor *)
         (v::vl, tl, f)
 
 let let_map fn env t1 tb =