diff -r 8cbc8bc6f382 -r c1aa8a61ee65 src/Pure/variable.ML
--- a/src/Pure/variable.ML	Sat Nov 30 13:40:57 2024 +0100
+++ b/src/Pure/variable.ML	Sat Nov 30 13:41:38 2024 +0100
@@ -594,7 +594,7 @@
 
 fun invent_types Ss ctxt =
   let
-    val tfrees = Name.invent (names_of ctxt) Name.aT (length Ss) ~~ Ss;
+    val tfrees = Name.invent_types (names_of ctxt) Ss;
     val ctxt' = fold (declare_constraints o Logic.mk_type o TFree) tfrees ctxt;
   in (tfrees, ctxt') end;