Reading Scala 3 class files from Scala 2.13 Ammonite.Main().run()

[fabianhjr]

From: https://docs.scala-lang.org/scala3/guides/migration/compatibility-classpath.html

A Scala 2.13 module can depend on a Scala 3 artifact

By enabling the TASTy reader with -Ytasty-reader, a Scala 2.13 module can depend on a Scala 3 artifact.

Minimum example: https://github.com/fabianhjr/ammonite-scala3-issue

Use case is debug repl

Attempted Workarounds

error while loading [Thing], Missing dependency 'Add -Ytasty-reader to scalac options to parse the TASTy in [Path]

Tried:

ammonite.Main(
  predefCode = "interp.configureCompiler(_.settings.processArguments(List(\"-Ytasty-reader\"), true))
)

ammonit.Main(
  predefFile = [Path to predef.sc with the above]
)

and

           ammonite
              .Main(
                compilerBuilder = new ICompilerBuilder {
                  override def create(
                      initialClassPath: Seq[URL],
                      classPath: Seq[URL],
                      dynamicClassPath: Seq[(String, Array[Byte])],
                      evalClassLoader: ClassLoader,
                      pluginClassLoader: ClassLoader,
                      reporter: Option[ICompilerBuilder.Message => Unit],
                      settings: Seq[String],
                      classPathWhiteList: Set[Seq[String]],
                      lineNumberModifier: Boolean
                  ): ICompiler =
                    CompilerBuilder.create(
                      initialClassPath,
                      classPath,
                      dynamicClassPath,
                      evalClassLoader,
                      pluginClassLoader,
                      reporter,
                      settings ++ Seq("-Ytasty-reader"),
                      classPathWhiteList,
                      lineNumberModifier
                    )

                  override def newManager(
                      rtCacheDir: Option[Path],
                      headFrame: => Frame,
                      dependencyCompleter: => Option[String => (Int, Seq[String])],
                      whiteList: Set[Seq[String]],
                      initialClassLoader: ClassLoader
                  ): CompilerLifecycleManager = CompilerBuilder
                    .newManager(rtCacheDir, headFrame, dependencyCompleter, whiteList, initialClassLoader)

                  override def scalaVersion: String = CompilerBuilder.scalaVersion
                }

[fabianhjr]

Looking at the source of ammonite.Main.run seems like the replArgs get evaluated before other things.

  def run(replArgs: Bind[_]*): (Res[Any], Seq[(Watchable, Long)]) = {


    instantiateRepl(replArgs.toIndexedSeq) match{
      case Left(missingPredefInfo) => missingPredefInfo
      case Right(repl) =>

So I am a bit confused about how to add this flags to ammonite Main.run on the debug and instinctively I think this function might require an extra argument for the flags/settings. (Tough would appreciate maintainer input on whether such a change would be desired, can work on a fix on my spare time)

[fabianhjr]

Uploaded a minimum example to: https://github.com/fabianhjr/ammonite-scala3-issue

[ivanmoreau]

Hi Fabian! I think you MWE is wrong, as it does not represent the actual error that you are describing in your issue.