Make logging never repeat the same experimental warning

modules/build/src/main/scala/scala/build/internal/util/WarningMessages.scala

@@ -15,19 +15,31 @@ object WarningMessages {
        |If you encounter any bugs or have feedback to share, make sure to reach out to the maintenance team at $scalaCliGithubUrl""".stripMargin
   def experimentalFeaturesUsed(namesAndFeatureTypes: Seq[(String, FeatureType)]): String = {
     val message = namesAndFeatureTypes match {
-      case Seq((name, featureType)) => s"The $name $featureType is experimental"
+      case Seq((name, featureType)) => s"The `$name` $featureType is experimental"
       case namesAndTypes =>
-        val nl = System.lineSeparator()
-        val bulletPointList = namesAndTypes.map((name, fType) => s" - `$name` $fType")
-          .mkString(nl)
-        s"""Some utilized features are marked as experimental:
+        val nl                   = System.lineSeparator()
+        val distinctFeatureTypes = namesAndTypes.map(_._2).distinct
+        val (bulletPointList, featureNameToPrint) = if (distinctFeatureTypes.size == 1)
+          (
+            namesAndTypes.map((name, fType) => s" - `$name`")
+              .mkString(nl),
+            s"${distinctFeatureTypes.head}s" // plural form
+          )
+        else
+          (
+            namesAndTypes.map((name, fType) => s" - `$name` $fType")
+              .mkString(nl),
+            "features"
+          )
+
+        s"""Some utilized $featureNameToPrint are marked as experimental:
            |$bulletPointList""".stripMargin
     }
     s"""$message
        |$experimentalNote""".stripMargin
   }
 
-  def experimentalSubcommandUsed(name: String): String =
+  def experimentalSubcommandWarning(name: String): String =
     s"""The `$name` sub-command is experimental.
        |$experimentalNote""".stripMargin
 

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

@@ -289,12 +289,12 @@ abstract class ScalaCommand[T <: HasGlobalOptions](implicit myParser: Parser[T],
             message =
               s"""${hm.message}
                  |
-                 |${WarningMessages.experimentalSubcommandUsed(name)}""".stripMargin,
+                 |${WarningMessages.experimentalSubcommandWarning(name)}""".stripMargin,
             detailedMessage =
               if hm.detailedMessage.nonEmpty then
                 s"""${hm.detailedMessage}
                    |
-                   |${WarningMessages.experimentalSubcommandUsed(name)}""".stripMargin
+                   |${WarningMessages.experimentalSubcommandWarning(name)}""".stripMargin
               else hm.detailedMessage
           )
         )
@@ -347,8 +347,6 @@ abstract class ScalaCommand[T <: HasGlobalOptions](implicit myParser: Parser[T],
     * start of running every [[ScalaCommand]].
     */
   final override def run(options: T, remainingArgs: RemainingArgs): Unit = {
-    logger.flushExperimentalWarnings
-
     CurrentParams.verbosity = options.global.logging.verbosity
     if shouldExcludeInSip then
       logger.error(WarningMessages.powerCommandUsedInSip(
@@ -357,13 +355,15 @@ abstract class ScalaCommand[T <: HasGlobalOptions](implicit myParser: Parser[T],
       ))
       sys.exit(1)
     else if isExperimental && !shouldSuppressExperimentalFeatureWarnings then
-      logger.message(WarningMessages.experimentalSubcommandUsed(name))
+      logger.experimentalWarning(name, FeatureType.Subcommand)
+
     maybePrintWarnings(options)
     maybePrintGroupHelp(options)
     buildOptions(options).foreach { bo =>
       maybePrintSimpleScalacOutput(options, bo)
       maybePrintToolsHelp(options, bo)
     }
+    logger.flushExperimentalWarnings
     runCommand(options, remainingArgs, options.global.logging.logger)
   }
 }

modules/cli/src/main/scala/scala/cli/internal/CliLogger.scala

@@ -209,22 +209,28 @@ class CliLogger(
   // Allow to disable that?
   def compilerOutputStream = out
 
-  private var experimentalWarnings: Map[FeatureType, Set[String]] = Map()
-  def experimentalWarning(featureName: String, featureType: FeatureType): Unit = {
-    experimentalWarnings ++= experimentalWarnings.updatedWith(featureType) {
-      case None           => Some(Set(featureName))
-      case Some(namesSet) => Some(namesSet + featureName)
-    }
-  }
+  private var experimentalWarnings: Map[FeatureType, Set[String]] = Map.empty
+  private var reported: Map[FeatureType, Set[String]]             = Map.empty
+  def experimentalWarning(featureName: String, featureType: FeatureType): Unit =
+    if (!reported.get(featureType).exists(_.contains(featureName)))
+      experimentalWarnings ++= experimentalWarnings.updatedWith(featureType) {
+        case None           => Some(Set(featureName))
+        case Some(namesSet) => Some(namesSet + featureName)
+      }
   def flushExperimentalWarnings: Unit = if (experimentalWarnings.nonEmpty) {
-    val messageStr = {
+    val messageStr: String = {
       val namesAndTypes = for {
-        (featureType, names) <- experimentalWarnings.toSeq
+        (featureType, names) <- experimentalWarnings.toSeq.sortBy(_._1) // by feature type
         name                 <- names
       } yield name -> featureType
       WarningMessages.experimentalFeaturesUsed(namesAndTypes)
     }
     message(messageStr)
+    reported = for {
+      (featureType, names) <- experimentalWarnings
+      reportedNames = reported.getOrElse(featureType, Set.empty[String])
+    } yield featureType -> (names ++ reportedNames)
+    experimentalWarnings = Map.empty
   }
 }
 

modules/core/src/main/scala/scala/build/internals/FeatureType.scala

@@ -8,3 +8,14 @@ enum FeatureType(stringRepr: String) {
   case Subcommand extends FeatureType("sub-command")
   case ConfigKey  extends FeatureType("configuration key")
 }
+
+object FeatureType {
+  private val ordering = Map(
+    FeatureType.Subcommand -> 0,
+    FeatureType.Option     -> 1,
+    FeatureType.Directive  -> 2,
+    FeatureType.ConfigKey  -> 3
+  )
+
+  given Ordering[FeatureType] = Ordering.by(ordering)
+}

modules/integration/src/test/scala/scala/cli/integration/SipScalaTests.scala

@@ -8,13 +8,12 @@ import scala.util.Properties
 class SipScalaTests extends ScalaCliSuite {
 
   implicit class StringEnrichment(s: String) {
-    def containsExperimentalWarningOf(featureNameAndType: String) =
+    def containsExperimentalWarningOf(featureNameAndType: String): Boolean =
       s.contains(s"The $featureNameAndType is experimental") ||
-        s.linesIterator
-          .dropWhile(_ != "Some utilized features are marked as experimental:")
-          .takeWhile(_ != "Please bear in mind that non-ideal user experience should be expected.")
-          .tapEach(println)
-          .contains(s" - $featureNameAndType")
+      s.linesIterator
+        .dropWhile(!_.endsWith("are marked as experimental:"))
+        .takeWhile(_ != "Please bear in mind that non-ideal user experience should be expected.")
+        .contains(s" - $featureNameAndType")
   }
 
   implicit class BinaryNameOps(binaryName: String) {
@@ -208,15 +207,15 @@ class SipScalaTests extends ScalaCliSuite {
         case (true, false) =>
           expect(res.exitCode == 0)
           expect(errOutput.containsExperimentalWarningOf(
-            "`//> using publish.name \"my-library\"` directive"
+            "`//> using publish.name \"my-library\"`"
           ))
-          expect(errOutput.containsExperimentalWarningOf("`//> using python` directive"))
+          expect(errOutput.containsExperimentalWarningOf("`//> using python`"))
         case (true, true) =>
           expect(res.exitCode == 0)
           expect(!errOutput.containsExperimentalWarningOf(
-            "`//> using publish.name \"my-library\"` directive"
+            "`//> using publish.name \"my-library\"`"
           ))
-          expect(!errOutput.containsExperimentalWarningOf("`//> using python` directive"))
+          expect(!errOutput.containsExperimentalWarningOf("`//> using python`"))
       }
     }
 
@@ -248,7 +247,9 @@ class SipScalaTests extends ScalaCliSuite {
       isPowerMode -> areWarningsSuppressed match {
         case (false, _) =>
           expect(res.exitCode == 1)
-          expect(errOutput.contains("Unrecognized argument: The `--markdown` option is experimental."))
+          expect(
+            errOutput.contains("Unrecognized argument: The `--markdown` option is experimental.")
+          )
         case (true, false) =>
           expect(res.exitCode == 0)
           expect(errOutput.containsExperimentalWarningOf("`--markdown` option"))
@@ -415,4 +416,46 @@ class SipScalaTests extends ScalaCliSuite {
         }
       )
     }
+
+  test("test multiple sources of experimental features") {
+    val inputs = TestInputs(
+      os.rel / "Main.scala" ->
+        """//> using target.scope main
+          |//> using target.platform jvm
+          |//> using publish.name "my-library"
+          |
+          |object Main {
+          |  def main(args: Array[String]): Unit = {
+          |    println("Hello World!")
+          |  }
+          |}
+          |""".stripMargin
+    )
+
+    inputs.fromRoot { root =>
+      val res = os.proc(TestUtil.cli, "--power", "export", ".", "--object-wrapper", "--md")
+        .call(cwd = root, mergeErrIntoOut = true)
+
+      val output = res.out.trim
+
+      assertNoDiff(
+        output,
+        s"""Some utilized features are marked as experimental:
+           | - `export` sub-command
+           | - `--object-wrapper` option
+           | - `--md` option
+           |Please bear in mind that non-ideal user experience should be expected.
+           |If you encounter any bugs or have feedback to share, make sure to reach out to the maintenance team at https://github.com/VirtusLab/scala-cli
+           |Exporting to a sbt project...
+           |Some utilized directives are marked as experimental:
+           | - `//> using publish.name "my-library"`
+           | - `//> using target.scope "main"`
+           | - `//> using target.platform "jvm"`
+           |Please bear in mind that non-ideal user experience should be expected.
+           |If you encounter any bugs or have feedback to share, make sure to reach out to the maintenance team at https://github.com/VirtusLab/scala-cli
+           |Exported to: $root/dest
+           |""".stripMargin
+      )
+    }
+  }
 }