diff -r 9efdebe24c65 -r 0ffcad1f6130 src/Pure/Admin/components.scala
--- a/src/Pure/Admin/components.scala	Mon Mar 01 20:12:09 2021 +0100
+++ b/src/Pure/Admin/components.scala	Mon Mar 01 22:22:12 2021 +0100
@@ -59,7 +59,7 @@
   def resolve(base_dir: Path, names: List[String],
     target_dir: Option[Path] = None,
     copy_dir: Option[Path] = None,
-    progress: Progress = new Progress)
+    progress: Progress = new Progress): Unit =
   {
     Isabelle_System.make_directory(base_dir)
     for (name <- names) {
@@ -78,7 +78,7 @@
     }
   }
 
-  def purge(dir: Path, platform: Platform.Family.Value)
+  def purge(dir: Path, platform: Platform.Family.Value): Unit =
   {
     def purge_platforms(platforms: String*): Set[String] =
       platforms.flatMap(name =>
@@ -191,7 +191,7 @@
     progress: Progress = new Progress,
     publish: Boolean = false,
     force: Boolean = false,
-    update_components_sha1: Boolean = false)
+    update_components_sha1: Boolean = false): Unit =
   {
     val archives: List[Path] =
       for (path <- components) yield {