diff -r e1c9e4d59921 -r 39011d0d2128 src/Pure/System/scala.scala
--- a/src/Pure/System/scala.scala	Sat Apr 09 15:40:29 2022 +0200
+++ b/src/Pure/System/scala.scala	Thu Apr 21 10:03:38 2022 +0200
@@ -235,7 +235,7 @@
       }
     }
 
-    override val functions =
+    override val functions: Session.Protocol_Functions =
       List(
         Markup.Invoke_Scala.name -> invoke_scala,
         Markup.Cancel_Scala.name -> cancel_scala)