diff -r 5f160df596c1 -r 60d0ee8f2ddb src/Pure/System/progress.scala
--- a/src/Pure/System/progress.scala	Sun Feb 17 22:15:02 2019 +0100
+++ b/src/Pure/System/progress.scala	Mon Feb 18 15:57:06 2019 +0100
@@ -28,7 +28,7 @@
   def echo(msg: String) {}
   def echo_if(cond: Boolean, msg: String) { if (cond) echo(msg) }
   def theory(theory: Progress.Theory) {}
-  def nodes_status(snapshot: Document.Snapshot, nodes_status: Document_Status.Nodes_Status) {}
+  def nodes_status(nodes_status: Document_Status.Nodes_Status) {}
 
   def echo_warning(msg: String) { echo(Output.warning_text(msg)) }
   def echo_error_message(msg: String) { echo(Output.error_message_text(msg)) }