Better output in revolver mode

Author: alexarchambault

modules/cli/src/main/scala/scala/cli/commands/WatchUtil.scala

@@ -11,14 +11,21 @@ object WatchUtil {
   def waitMessage(message: String): String = {
     // Both short cuts actually always work, but Ctrl+C also exits mill in mill watch mode.
     val shortCut = if (isDevMode) "Ctrl+D" else "Ctrl+C"
-    val gray     = "\u001b[90m"
-    val reset    = Console.RESET
-    s"$gray$message, press $shortCut to exit, or press Enter to re-run.$reset"
+    gray(s"$message, press $shortCut to exit, or press Enter to re-run.")
+  }
+
+  private def gray(message: String): String = {
+    val gray  = "\u001b[90m"
+    val reset = Console.RESET
+    s"$gray$message$reset"
   }
 
   def printWatchMessage(): Unit =
     System.err.println(waitMessage("Watching sources"))
 
+  def printWatchWhileRunningMessage(): Unit =
+    System.err.println(gray("Watching sources while your program is running."))
+
   def waitForCtrlC(
     onPressEnter: () => Unit = () => (),
     shouldReadInput: () => Boolean = () => true

modules/cli/src/main/scala/scala/cli/commands/run/Run.scala

@@ -152,17 +152,22 @@ object Run extends ScalaCommand[RunOptions] with BuildCommandHelpers {
             val onExitProcess = process.onExit().thenApply { p1 =>
               val retCode = p1.exitValue()
               onExitOpt.foreach(_())
-              if (retCode != 0)
-                if (allowTerminate)
+              (retCode, allowTerminate) match {
+                case (0, true) =>
+                case (0, false) =>
+                  val gray  = "\u001b[90m"
+                  val reset = Console.RESET
+                  System.err.println(s"${gray}Program exited with return code $retCode.$reset")
+                case (_, true) =>
                   sys.exit(retCode)
-                else {
+                case (_, false) =>
                   val red      = Console.RED
                   val lightRed = "\u001b[91m"
                   val reset    = Console.RESET
                   System.err.println(
                     s"${red}Program exited with return code $lightRed$retCode$red.$reset"
                   )
-                }
+              }
             }
 
             Some((process, onExitProcess))
@@ -207,7 +212,11 @@ object Run extends ScalaCommand[RunOptions] with BuildCommandHelpers {
         buildTests = false,
         partial = None,
         actionableDiagnostics = actionableDiagnostics,
-        postAction = () => WatchUtil.printWatchMessage()
+        postAction = () =>
+          if (processOpt.exists(_._1.isAlive()))
+            WatchUtil.printWatchWhileRunningMessage()
+          else
+            WatchUtil.printWatchMessage()
       ) { res =>
         for ((process, onExitProcess) <- processOpt) {
           onExitProcess.cancel(true)