src/HOL/Nominal/nominal_datatype.ML

--- a/src/HOL/Nominal/nominal_datatype.ML	Wed Oct 20 17:11:46 2021 +0200
+++ b/src/HOL/Nominal/nominal_datatype.ML	Wed Oct 20 18:13:17 2021 +0200
@@ -55,7 +55,6 @@
 (
   type T = nominal_datatype_info Symtab.table;
   val empty = Symtab.empty;
-  val extend = I;
   fun merge data = Symtab.merge (K true) data;
 );