src/Pure/Syntax/syntax_phases.ML

     val syn = Proof_Context.syn_of ctxt;
     val ast_tr = Syntax.parse_ast_translation syn;
 
     val toks = Syntax.tokenize syn raw syms;
     val _ = Context_Position.reports ctxt (map Lexicon.report_of_token toks);
-    val _ = toks |> List.app (fn tok =>
-      (case Lexicon.kind_of_token tok of
-        Lexicon.Comment NONE =>
-          legacy_feature ("Old-style inner comment: use \"\<comment> \<open>...\<close>\" or \"\<^cancel>\<open>...\<close>\" instead" ^
-            Position.here (Lexicon.pos_of_token tok))
-      | _ => ()));
 
     val pts = Syntax.parse syn root (filter Lexicon.is_proper toks)
       handle ERROR msg =>
         error (msg ^ Markup.markup_report (implode (map (Lexicon.reported_token_range ctxt) toks)));
     val len = length pts;