Move meta build source check into Command.processCommand

We want to check the build sources before any command runs, not just
tasks. To achieve this, I moved the logic for checking for build source
changes to CommandProcess.processCommand. Also, @smarter had noticed
that if a user modified a build file and then ran reload, a warning
would be displayed about changed build sources even though they had just
ran reload. This was because running reload didn't update the previous
cache for checkBuildSources / fileInputStamps. I fixed that bug by
running 'checkBuildSources / changedInputFiles' instead of
'checkBuildSources' when the user runs reload.

I verified that after this change:

- If I changed a build file and ran 'show version' a warning was printed
  before it displayed the version. If I also set
  global / onChangedBuildSource := ReloadOnSourceChanges, it
  automatically reloaded before displaying the version.
- If I changed a build source and ran 'reload', followed by
  'show version', no warnings were ever displayed.

As an implementation detail, I had to add the Aggregation.suppressShow
attribute key. We set this key to true before checking the build
sources. Without this, log.success is called whenever we check the build
sources which is both confusing and noisy.

main/src/main/scala/sbt/Defaults.scala

@@ -255,6 +255,7 @@ object Defaults extends BuildCommon {
       buildStructure := Project.structure(state.value),
       settingsData := buildStructure.value.data,
       aggregate in checkBuildSources :== false,
+      aggregate in checkBuildSources / changedInputFiles := false,
       checkBuildSources / Continuous.dynamicInputs := None,
       checkBuildSources / fileInputs := CheckBuildSources.buildSourceFileInputs.value,
       checkBuildSources := CheckBuildSources.needReloadImpl.value,

main/src/main/scala/sbt/EvaluateTask.scala

@@ -19,7 +19,6 @@ import sbt.internal.TaskName._
 import sbt.internal._
 import sbt.internal.util._
 import sbt.librarymanagement.{ Resolver, UpdateReport }
-import sbt.nio.Keys.IgnoreSourceChanges
 import sbt.std.Transform.DummyTaskMap
 import sbt.util.{ Logger, Show }
 
@@ -355,7 +354,7 @@ object EvaluateTask {
       val msgString = (msg.toList ++ ex.toList.map(ErrorHandling.reducedToString)).mkString("\n\t")
       val log = getStreams(key, streams).log
       val display = contextDisplay(state, ConsoleAppender.formatEnabledInEnv)
-      log.error("(" + display.show(key) + ") " + msgString)
+      if (!ex.contains(Reload)) log.error("(" + display.show(key) + ") " + msgString)
     }
   }
 
@@ -440,7 +439,7 @@ object EvaluateTask {
       case Some(t: Task[_]) => transformNode(t).isEmpty
       case _                => true
     }
-    def run[R](s: State, toRun: Task[R], doShutdown: Boolean) = {
+    def run() = {
       val x = new Execute[Task](
         Execute.config(config.checkCycles, overwriteNode),
         triggers,
@@ -448,12 +447,12 @@ object EvaluateTask {
       )(taskToNode)
       val (newState, result) =
         try {
-          val results = x.runKeep(toRun)(service)
+          val results = x.runKeep(root)(service)
-          storeValuesForPrevious(results, s, streams)
+          storeValuesForPrevious(results, state, streams)
-          applyResults(results, s, toRun)
+          applyResults(results, state, root)
-        } catch { case inc: Incomplete => (s, Inc(inc)) } finally if (doShutdown) shutdown()
+        } catch { case inc: Incomplete => (state, Inc(inc)) } finally shutdown()
       val replaced = transformInc(result)
-      logIncResult(replaced, s, streams)
+      logIncResult(replaced, state, streams)
       (newState, replaced)
     }
     object runningEngine extends RunningTaskEngine {
@@ -468,24 +467,8 @@ object EvaluateTask {
     val strat = config.cancelStrategy
     val cancelState = strat.onTaskEngineStart(runningEngine)
     config.progressReporter.initial()
-    try {
+    try run()
-      (state.get(stateBuildStructure), state.get(sessionSettings)) match {
+    finally {
-        case (Some(structure), Some(settings)) =>
-          val extracted: Extracted = Project.extract(settings, structure)
-          if (extracted.get(sbt.nio.Keys.onChangedBuildSource) == IgnoreSourceChanges) {
-            run(state, root, doShutdown = true)
-          } else {
-            run(state, extracted.get(sbt.nio.Keys.checkBuildSources), doShutdown = false) match {
-              case (newState, r) =>
-                r.toEither match {
-                  case Left(i) => (newState, Result.fromEither(Left(i)))
-                  case _       => run(newState, root, doShutdown = true)
-                }
-            }
-          }
-        case _ => run(state, root, doShutdown = true)
-      }
-    } finally {
       strat.onTaskEngineFinish(cancelState)
       currentlyRunningEngine.set(null)
       lastEvaluatedState.set(SafeState(state))

main/src/main/scala/sbt/MainLoop.scala

@@ -11,8 +11,9 @@ import java.io.PrintWriter
 import java.util.Properties
 
 import jline.TerminalFactory
-import sbt.internal.ShutdownHooks
+import sbt.internal.{ Aggregation, ShutdownHooks }
 import sbt.internal.langserver.ErrorCodes
+import sbt.internal.util.complete.Parser
 import sbt.internal.util.{ ErrorHandling, GlobalLogBacking }
 import sbt.io.{ IO, Using }
 import sbt.protocol._
@@ -189,23 +190,47 @@ object MainLoop {
       ExecStatusEvent("Processing", channelName, exec.execId, Vector())
 
     try {
-      val newState = runCommand()
+      def process(): State = {
-      val doneEvent = ExecStatusEvent(
+        val newState = runCommand()
-        "Done",
+        val doneEvent = ExecStatusEvent(
-        channelName,
+          "Done",
-        exec.execId,
+          channelName,
-        newState.remainingCommands.toVector map (_.commandLine),
+          exec.execId,
-        exitCode(newState, state),
+          newState.remainingCommands.toVector map (_.commandLine),
-      )
+          exitCode(newState, state),
-      if (doneEvent.execId.isDefined) { // send back a response or error
+        )
-        import sbt.protocol.codec.JsonProtocol._
+        if (doneEvent.execId.isDefined) { // send back a response or error
-        StandardMain.exchange publishEvent doneEvent
+          import sbt.protocol.codec.JsonProtocol._
-      } else { // send back a notification
+          StandardMain.exchange publishEvent doneEvent
-        StandardMain.exchange publishEventMessage doneEvent
+        } else { // send back a notification
+          StandardMain.exchange publishEventMessage doneEvent
+        }
+        newState
+      }
+      val checkCommand = state.currentCommand match {
+        // If the user runs reload directly, we want to be sure that we update the previous
+        // cache for checkBuildSources / changedInputFiles but we don't want to display any
+        // warnings. Without filling the previous cache, it's possible for the user to run
+        // reload and be prompted with a warning in spite of reload having just run and no build
+        // sources having changed.
+        case Some(exec) if exec.commandLine == "reload" => "checkBuildSources / changedInputFiles"
+        case _                                          => "checkBuildSources"
+      }
+      Parser.parse(
+        checkCommand,
+        state.put(Aggregation.suppressShow, true).combinedParser
+      ) match {
+        case Right(cmd) =>
+          cmd() match {
+            case s if s.remainingCommands.headOption.map(_.commandLine).contains("reload") =>
+              s.remove(Aggregation.suppressShow)
+            case _ => process()
+          }
+        case Left(_) => process()
       }
-      newState
     } catch {
       case err: Throwable =>
+        err.printStackTrace()
         val errorEvent = ExecStatusEvent(
           "Error",
           channelName,

main/src/main/scala/sbt/internal/Aggregation.scala

@@ -9,14 +9,17 @@ package sbt
 package internal
 
 import java.text.DateFormat
+
 import Def.ScopedKey
 import Keys.{ showSuccess, showTiming, timingFormat }
 import sbt.internal.util.complete.Parser
-import sbt.internal.util.{ Dag, HList, Settings, Util }
+import sbt.internal.util.{ AttributeKey, Dag, HList, Settings, Util }
 import sbt.util.{ Logger, Show }
 import Parser.{ failure, seq, success }
 import std.Transform.DummyTaskMap
 
+import scala.annotation.tailrec
+
 sealed trait Aggregation
 object Aggregation {
   final case class ShowConfig(
@@ -76,7 +79,8 @@ object Aggregation {
     results.toEither.right.foreach { r =>
       if (show.taskValues) printSettings(r, show.print)
     }
-    if (show.success) printSuccess(start, stop, extracted, success, log)
+    if (show.success && !state.get(suppressShow).getOrElse(false))
+      printSuccess(start, stop, extracted, success, log)
   }
 
   def timedRun[T](
@@ -110,8 +114,19 @@ object Aggregation {
   )(implicit display: Show[ScopedKey[_]]): State = {
     val complete = timedRun[T](s, ts, extra)
     showRun(complete, show)
+    @tailrec def findReload(
+        incomplete: Incomplete,
+        remaining: List[Incomplete],
+        visited: Set[Incomplete]
+    ): Boolean = {
+      incomplete.directCause.contains(Reload) || ((remaining ::: incomplete.causes.toList)
+        .filterNot(visited) match {
+        case Nil       => false
+        case h :: tail => findReload(h, tail.filterNot(visited), visited + incomplete)
+      })
+    }
     complete.results match {
-      case Inc(i) if i.directCause.contains(Reload) =>
+      case Inc(i) if findReload(i, i.causes.toList, Set.empty) =>
         val remaining = s.currentCommand.toList ::: s.remainingCommands
         complete.state.copy(remainingCommands = Exec("reload", None, None) :: remaining)
       case Inc(i)   => complete.state.handleError(i)
@@ -289,4 +304,6 @@ object Aggregation {
 
   def aggregationEnabled(key: ScopedKey[_], data: Settings[Scope]): Boolean =
     Keys.aggregate in Scope.fillTaskAxis(key.scope, key.key) get data getOrElse true
+  private[sbt] val suppressShow =
+    AttributeKey[Boolean]("suppress-aggregation-show", Int.MaxValue)
 }