src/Pure/pure_thy.ML

--- a/src/Pure/pure_thy.ML	Wed Oct 20 17:11:46 2021 +0200
+++ b/src/Pure/pure_thy.ML	Wed Oct 20 18:13:17 2021 +0200
@@ -46,7 +46,6 @@
 (
   type T = bool;
   val empty = false;
-  val extend = I;
   fun merge (b1, b2) : T =
     if b1 = b2 then b1
     else error "Cannot merge theories with different application syntax";