diff -r f249b5c0fea2 -r 16aa085f9353 src/Pure/Concurrent/isabelle_thread.ML
--- a/src/Pure/Concurrent/isabelle_thread.ML	Sun Apr 05 13:19:29 2020 +0200
+++ b/src/Pure/Concurrent/isabelle_thread.ML	Sun Apr 05 13:24:12 2020 +0200
@@ -7,8 +7,7 @@
 signature ISABELLE_THREAD =
 sig
   val is_self: Thread.thread -> bool
-  val get_name: unit -> string option
-  val the_name: unit -> string
+  val get_name: unit -> string
   type params = {name: string, stack_limit: int option, interrupts: bool}
   val attributes: params -> Thread.threadAttribute list
   val fork: params -> (unit -> unit) -> Thread.thread
@@ -31,12 +30,10 @@
   val count = Counter.make ();
 in
 
-fun get_name () = Thread_Data.get name_var;
-
-fun the_name () =
-  (case get_name () of
-    NONE => raise Fail "Unknown thread name"
-  | SOME name => name);
+fun get_name () =
+  (case Thread_Data.get name_var of
+    SOME name => name
+  | NONE => raise Fail "Isabelle-specific thread required");
 
 fun set_name base =
   Thread_Data.put name_var (SOME ("Isabelle." ^ base ^ "-" ^ string_of_int (count ())));