Post processors can now report warnig.

We report such warning and skip processing of TASTY files when we face a Scala Version with newer Tasty then we know we support.

Author: romanowski

modules/build/src/main/scala/scala/build/Build.scala

@@ -616,8 +616,9 @@ object Build {
         logger,
         inputs.workspace,
         updateSemanticDbs = true,
-        updateTasty = project.scalaCompiler.scalaVersion.startsWith("3.")
+        scalaVersion = project.scalaCompiler.scalaVersion
       )
+        .left.foreach(_.foreach(logger.message(_)))
 
       Successful(
         inputs,
@@ -650,8 +651,8 @@ object Build {
     logger: Logger,
     workspace: os.Path,
     updateSemanticDbs: Boolean,
-    updateTasty: Boolean
-  ): Unit = {
+    scalaVersion: String
+  ): Either[Seq[String], Unit] = {
 
     // TODO Write classes to a separate directory during post-processing
     logger.debug("Post-processing class files of pre-processed sources")
@@ -668,10 +669,13 @@ object Build {
     val postProcessors =
       Seq(ByteCodePostProcessor) ++
         (if (updateSemanticDbs) Seq(SemanticDbPostProcessor) else Nil) ++
-        (if (updateTasty) Seq(TastyPostProcessor) else Nil)
+        Seq(TastyPostProcessor)
 
-    for (p <- postProcessors)
-      p.postProcess(generatedSources, mappings, workspace, classesDir, logger)
+    val failures = postProcessors.flatMap(
+      _.postProcess(generatedSources, mappings, workspace, classesDir, logger, scalaVersion)
+        .fold(e => Seq(e), _ => Nil)
+    )
+    if (failures.isEmpty) Right(()) else Left(failures)
   }
 
   def onChangeBufferedObserver(onEvent: PathWatchers.Event => Unit): Observer[PathWatchers.Event] =

modules/build/src/main/scala/scala/build/bsp/BspImpl.scala

@@ -138,6 +138,18 @@ final class BspImpl(
           client.resetBuildExceptionDiagnostics(targetId)
     }
 
+  private val shownGlobalMessages =
+    new java.util.concurrent.ConcurrentHashMap[String, Unit]()
+
+  private def showGlobalWarningOnce(msg: String) =
+    shownGlobalMessages.computeIfAbsent(
+      msg,
+      _ => {
+        val params = new b.ShowMessageParams(b.MessageType.WARNING, msg)
+        actualLocalClient.onBuildShowMessage(params)
+      }
+    )
+
   def compile(
     actualLocalServer: BspServer,
     executor: Executor,
@@ -185,8 +197,8 @@ final class BspImpl(
                     logger,
                     inputs.workspace,
                     updateSemanticDbs = true,
-                    updateTasty = true
-                  )
+                    scalaVersion = project.scalaCompiler.scalaVersion
+                  ).left.foreach(_.foreach(showGlobalWarningOnce))
                   res
                 },
                 executor

modules/build/src/main/scala/scala/build/postprocessing/ByteCodePostProcessor.scala

@@ -1,14 +1,16 @@
 package scala.build.postprocessing
 
 import scala.build.{GeneratedSource, Logger}
+import scala.util.{Either, Right}
 
 case object ByteCodePostProcessor extends PostProcessor {
   def postProcess(
     generatedSources: Seq[GeneratedSource],
     mappings: Map[String, (String, Int)],
     workspace: os.Path,
     output: os.Path,
-    logger: Logger
-  ): Unit =
-    AsmPositionUpdater.postProcess(mappings, output, logger)
+    logger: Logger,
+    scalaVersion: String
+  ): Either[String, Unit] =
+    Right(AsmPositionUpdater.postProcess(mappings, output, logger))
 }

modules/build/src/main/scala/scala/build/postprocessing/PostProcessor.scala

@@ -8,6 +8,7 @@ trait PostProcessor {
     mappings: Map[String, (String, Int)],
     workspace: os.Path,
     output: os.Path,
-    logger: Logger
-  ): Unit
+    logger: Logger,
+    scalaVersion: String
+  ): Either[String, Unit]
 }

modules/build/src/main/scala/scala/build/postprocessing/SemanticDbPostProcessor.scala

@@ -4,15 +4,16 @@ import java.nio.file.FileSystemException
 
 import scala.annotation.tailrec
 import scala.build.{GeneratedSource, Logger}
-
+import scala.util.{Either, Right}
 case object SemanticDbPostProcessor extends PostProcessor {
   def postProcess(
     generatedSources: Seq[GeneratedSource],
     mappings: Map[String, (String, Int)],
     workspace: os.Path,
     output: os.Path,
-    logger: Logger
-  ): Unit = {
+    logger: Logger,
+    scalaVersion: String
+  ): Either[String, Unit] = Right {
     logger.debug("Moving semantic DBs around")
     val semDbRoot = output / "META-INF" / "semanticdb"
     for (source <- generatedSources; originalSource <- source.reportingPath) {

modules/build/src/main/scala/scala/build/postprocessing/TastyPostProcessor.scala

@@ -1,18 +1,21 @@
 package scala.build.postprocessing
 
-import scala.build.tastylib.TastyData
+import scala.build.internal.Constants
+import scala.build.tastylib.{TastyData, TastyVersions}
 import scala.build.{GeneratedSource, Logger}
 
 case object TastyPostProcessor extends PostProcessor {
+
   def postProcess(
     generatedSources: Seq[GeneratedSource],
     mappings: Map[String, (String, Int)],
     workspace: os.Path,
     output: os.Path,
-    logger: Logger
-  ): Unit = {
+    logger: Logger,
+    scalaVersion: String
+  ): Either[String, Unit] = {
 
-    val updatedPaths = generatedSources
+    def updatedPaths = generatedSources
       .flatMap { source =>
         source.reportingPath.toOption.toSeq.map { originalSource =>
           val fromSourceRoot = source.generated.relativeTo(workspace)
@@ -22,32 +25,45 @@ case object TastyPostProcessor extends PostProcessor {
       }
       .toMap
 
-    if (updatedPaths.nonEmpty)
-      os.walk(output)
-        .filter(os.isFile(_))
-        .filter(_.last.endsWith(".tasty")) // make that case-insensitive just in case?
-        .foreach { f =>
-          logger.debug(s"Reading TASTy file $f")
-          val content = os.read.bytes(f)
-          val data    = TastyData.read(content)
-          logger.debug(s"Parsed TASTy file $f")
-          var updatedOne = false
-          val updatedData = data.mapNames { n =>
-            updatedPaths.get(n) match {
-              case Some(newName) =>
-                updatedOne = true
-                newName
-              case None =>
-                n
-            }
-          }
-          if (updatedOne) {
-            logger.debug(
-              s"Overwriting ${if (f.startsWith(os.pwd)) f.relativeTo(os.pwd) else f}"
-            )
-            val updatedContent = TastyData.write(updatedData)
-            os.write.over(f, updatedContent)
-          }
-        }
+    TastyVersions.shouldRunPreprocessor(scalaVersion, Constants.version) match {
+      case Right(false) => Right(())
+      case Left(msg)    => if (updatedPaths.isEmpty) Right(()) else Left(msg)
+      case Right(true) =>
+        val paths = updatedPaths
+        if (paths.isEmpty) Right(())
+        else Right(
+          os.walk(output)
+            .filter(os.isFile(_))
+            .filter(_.last.endsWith(".tasty")) // make that case-insensitive just in case?
+            .foreach(updateTastyFile(logger, paths))
+        )
+    }
+  }
+
+  private def updateTastyFile(
+    logger: Logger,
+    updatedPaths: Map[String, String]
+  )(f: os.Path): Unit = {
+    logger.debug(s"Reading TASTy file $f")
+    val content = os.read.bytes(f)
+    val data    = TastyData.read(content)
+    logger.debug(s"Parsed TASTy file $f")
+    var updatedOne = false
+    val updatedData = data.mapNames { n =>
+      updatedPaths.get(n) match {
+        case Some(newName) =>
+          updatedOne = true
+          newName
+        case None =>
+          n
+      }
+    }
+    if (updatedOne) {
+      logger.debug(
+        s"Overwriting ${if (f.startsWith(os.pwd)) f.relativeTo(os.pwd) else f}"
+      )
+      val updatedContent = TastyData.write(updatedData)
+      os.write.over(f, updatedContent)
+    }
   }
 }

modules/tasty-lib/src/main/scala/scala/build/tastylib/TastyFormat.scala

@@ -18,10 +18,6 @@ object TastyFormat {
 
   final val header: Array[Int] = Array(0x5c, 0xa1, 0xab, 0x1f)
 
-  final val MajorVersion: Int        = 28
-  final val MinorVersion: Int        = 1
-  final val ExperimentalVersion: Int = 0
-
   def isVersionCompatible(
     fileMajor: Int,
     fileMinor: Int,

modules/tasty-lib/src/main/scala/scala/build/tastylib/TastyHeaderUnpickler.scala

@@ -16,7 +16,8 @@ package scala.build.tastylib
 
 import java.util.UUID
 
-import scala.build.tastylib.TastyFormat.{ExperimentalVersion, MajorVersion, MinorVersion, header}
+import scala.build.tastylib.TastyFormat.header
+import scala.build.tastylib.TastyVersions.{ExperimentalVersion, MajorVersion, MinorVersion}
 
 class TastyHeaderUnpickler(reader: TastyReader) {
   import TastyHeaderUnpickler._

modules/tasty-lib/src/main/scala/scala/build/tastylib/TastyVersions.scala

@@ -0,0 +1,32 @@
+package scala.build.tastylib
+
+object TastyVersions {
+
+  // Every time tasty version is updated, please update LatestSupportedScala as well!
+  final val MajorVersion: Int        = 28
+  final val MinorVersion: Int        = 1
+  final val ExperimentalVersion: Int = 0
+
+  object LatestSupportedScala {
+    final val MajorVersion: Int = 3
+    final val MinorVersion: Int = 1
+  }
+
+  def shouldRunPreprocessor(
+    scalaVersion: String,
+    scalaCliVersion: String
+  ): Either[String, Boolean] =
+    if (!scalaVersion.startsWith("3.")) Right(false)
+    else
+      scalaVersion.split('.')(1).toInt match {
+        case scalaMinor if scalaMinor > LatestSupportedScala.MinorVersion =>
+          Left(
+            s"Scala CLI (v. $scalaCliVersion) cannot post process TASTY files from Scala $scalaVersion.\n" +
+              s"This is not a fatal error since post processing only cleans up source paths in TASTY file " +
+              s"and it should not affect your application.\n" +
+              s"To get rid of this message, please update Scala CLI version."
+          )
+        case _ =>
+          Right(true)
+      }
+}