Adjust TASTY bump warnings to respect overridden Scala version defaults (#2888)

Author: Gedochao

build.sc

@@ -1180,7 +1180,7 @@ trait TastyLib extends ScalaCliCrossSbtModule
          |
          |/** Build-time constants. Generated by mill. */
          |object Constants {
-         |  def latestSupportedScala = "${Scala.defaultUser}"
+         |  def defaultScalaVersion = "${Scala.defaultUser}"
          |}
          |""".stripMargin
     if (!os.isFile(dest) || os.read(dest) != code)

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

@@ -27,7 +27,11 @@ case object TastyPostProcessor extends PostProcessor {
       }
       .toMap
 
-    TastyVersions.shouldRunPreprocessor(scalaVersion, Constants.version) match {
+    TastyVersions.shouldRunPreprocessor(
+      scalaVersion,
+      Constants.version,
+      buildOptions.scalaOptions.defaultScalaVersion
+    ) match {
       case Right(false) => Right(())
       case Left(msg)    => if (updatedPaths.isEmpty) Right(()) else Left(msg)
       case Right(true) =>

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

@@ -711,4 +711,26 @@ class SipScalaTests extends ScalaCliSuite with SbtTestHelper with MillTestHelper
       expect(exportRes.out.trim().contains(s""""scalaVersion": "$defaultSv""""))
     }
   }
+
+  test("no warnings about TASTY when using the latest nightly with scripts") {
+    val scriptName = "script.sc"
+    TestInputs(os.rel / "script.sc" -> "println(1)").fromRoot { root =>
+      val scala3Nightly =
+        os.proc(
+          TestUtil.cli,
+          "-e",
+          "println(dotty.tools.dotc.config.Properties.versionNumberString)",
+          "-S",
+          "3.nightly",
+          "--with-compiler"
+        )
+          .call(cwd = root)
+          .out.trim()
+      val res =
+        os.proc(TestUtil.cli, "--cli-default-scala-version", scala3Nightly, "run", scriptName)
+          .call(cwd = root, stderr = os.Pipe)
+      expect(res.exitCode == 0)
+      expect(!res.err.trim().contains("TASTY"))
+    }
+  }
 }

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

@@ -8,25 +8,21 @@ object TastyVersions {
     def majorVersion: Int               = version.split('.')(0).toInt
     def minorVersion: Int               = version.split('.')(1).toInt
     def minorVersionOption: Option[Int] = Try(minorVersion).toOption
-  }
-
-  // Every time tasty version is updated, please update LatestSupportedScala as well!
-  private object LatestSupportedScala {
-    final val MajorVersion: Int = Constants.latestSupportedScala.majorVersion
-    final val MinorVersion: Int = Constants.latestSupportedScala.minorVersion
-
-    def isLatestSupportedMajorVersion(scalaVersion: String): Boolean =
-      scalaVersion.startsWith(s"${LatestSupportedScala.MajorVersion}.") ||
-      scalaVersion == LatestSupportedScala.MajorVersion.toString
+    def isLatestSupportedMajorVersion(latestSupportedScalaVersion: String): Boolean = {
+      val latestSupportedMajor = latestSupportedScalaVersion.majorVersion.toString
+      version.startsWith(s"$latestSupportedMajor.") || version == latestSupportedMajor
+    }
   }
 
   def shouldRunPreprocessor(
     scalaVersion: String,
-    scalaCliVersion: String
-  ): Either[String, Boolean] =
-    if (!LatestSupportedScala.isLatestSupportedMajorVersion(scalaVersion)) Right(false)
+    scalaCliVersion: String,
+    defaultScalaVersion: Option[String]
+  ): Either[String, Boolean] = {
+    val scalaDefault = defaultScalaVersion.getOrElse(Constants.defaultScalaVersion)
+    if (!scalaVersion.isLatestSupportedMajorVersion(scalaDefault)) Right(false)
     else scalaVersion.minorVersionOption match {
-      case Some(scalaMinor) if scalaMinor > LatestSupportedScala.MinorVersion =>
+      case Some(scalaMinor) if scalaMinor > scalaDefault.minorVersion =>
         Left(
           s"""Scala CLI (v$scalaCliVersion) cannot post process TASTY files from Scala $scalaVersion.
              |This is not a fatal error since post processing only cleans up source paths in TASTY file.
@@ -38,4 +34,5 @@ object TastyVersions {
         )
       case _ => Right(true)
     }
+  }
 }