src/Pure/Isar/proof_context.ML

   in (sorting_report, (map o map_types) (replace_sortsT get_sort) tms) end;
 
 fun check_tfree ctxt v =
   let
     val (sorting_report, [TFree a]) = prepare_sortsT ctxt [TFree v];
-    val _ = Context_Position.if_visible ctxt Output.report sorting_report;
+    val _ = if Context_Position.is_visible ctxt then Output.report sorting_report else ();
   in a end;
 
 end;