src/Pure/Syntax/syntax_phases.ML

     val show_markup = Config.get ctxt show_markup;
     val show_sorts = Config.get ctxt show_sorts;
     val show_types = Config.get ctxt show_types orelse show_sorts;
 
     val syn = Proof_Context.syntax_of ctxt;
-    val prtabs = Syntax.prtabs syn;
+    val prtabs = Syntax.print_mode_tabs syn;
     val trf = Syntax.print_ast_translation syn;
     val markup_extern = (markup_entity_cache ctxt, extern_cache ctxt);
 
     val free_or_skolem_cache =
       #apply (Symtab.unsynchronized_cache (fn x => (markup_free ctxt x, extern_fixed ctxt x)));