BugFix - Export issues when full scala version is not used in directives

modules/cli/src/main/scala/scala/cli/exportCmd/MillProjectDescriptor.scala

@@ -38,9 +38,9 @@ final case class MillProjectDescriptor(
       options.classPathOptions.allExtraDependencies.toSeq
         .forall(_.value.nameAttributes == NoAttributes)
 
-    val sv = options.scalaOptions.scalaVersion
-      .flatMap(_.versionOpt) // FIXME If versionOpt is empty, the project is pure Java
-      .getOrElse(ScalaCli.getDefaultScalaVersion)
+    val sv = options.scalaParams.toOption.flatten.map(_.scalaVersion).getOrElse(
+      ScalaCli.getDefaultScalaVersion // FIXME account for pure Java projects, where Scala version isn't defined
+    )
 
     if (pureJava)
       MillProject()

modules/cli/src/main/scala/scala/cli/exportCmd/SbtProjectDescriptor.scala

@@ -121,9 +121,11 @@ final case class SbtProjectDescriptor(
   private def scalaVersionSettings(options: BuildOptions): SbtProject = {
 
     val scalaVerSetting = {
-      val sv = options.scalaOptions.scalaVersion
-        .flatMap(_.versionOpt) // FIXME If versionOpt is empty, the project is pure Java
-        .getOrElse(ScalaCli.getDefaultScalaVersion)
+
+      val sv = options.scalaParams.toOption.flatten.map(_.scalaVersion).getOrElse(
+        ScalaCli.getDefaultScalaVersion // FIXME account for pure Java projects, where Scala version isn't defined
+      )
+
       s"""scalaVersion := "$sv""""
     }
 

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

@@ -61,6 +61,16 @@ trait ExportCommonTestDefinitions { _: ScalaCliSuite & TestScalaVersionArgs =>
       expect(output.contains("Hello"))
     }
 
+  protected def scalaVersionTest(scalaVersion: String): Unit =
+    prepareTestInputs(ExportTestProjects.scalaVersionTest(scalaVersion)).fromRoot {
+      root =>
+        exportCommand(".").call(cwd = root, stdout = os.Inherit)
+        val res = buildToolCommand(root, runMainArgs*)
+          .call(cwd = root / outputDir)
+        val output = res.out.text(Charset.defaultCharset())
+        expect(output.contains("Hello"))
+    }
+
   def extraSourceFromDirectiveWithExtraDependency(inputs: String*): Unit =
     prepareTestInputs(
       ExportTestProjects.extraSourceFromDirectiveWithExtraDependency(actualScalaVersion)
@@ -86,6 +96,8 @@ trait ExportCommonTestDefinitions { _: ScalaCliSuite & TestScalaVersionArgs =>
     }
   }
 
+  private val scalaVersionsInDir: Seq[String] = Seq("2.12", "2.13", "2", "3", "3.lts")
+
   if (runExportTests) {
     test("compile-time only for jsoniter macros") {
       compileOnlyTest()
@@ -105,5 +117,11 @@ trait ExportCommonTestDefinitions { _: ScalaCliSuite & TestScalaVersionArgs =>
     test("extra source passed both via directive and from command line") {
       extraSourceFromDirectiveWithExtraDependency(".")
     }
+    scalaVersionsInDir.foreach { scalaV =>
+      test(s"check export for project with scala version in directive as $scalaV") {
+        scalaVersionTest(scalaV)
+      }
+    }
+
   }
 }

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

@@ -314,4 +314,14 @@ object ExportTestProjects {
            |}
            |""".stripMargin
     )
+
+  def scalaVersionTest(scalaVersion: String): TestInputs =
+    TestInputs(
+      os.rel / "Hello.scala" ->
+        s"""//> using scala $scalaVersion
+           |object Main extends App {
+           |        println("Hello")
+           |}
+           |""".stripMargin
+    )
 }

modules/options/src/main/scala/scala/build/options/ScalaOptions.scala

@@ -3,6 +3,7 @@ package scala.build.options
 import dependency.AnyDependency
 
 import scala.build.Positioned
+import scala.build.internal.Constants
 
 final case class ScalaOptions(
   scalaVersion: Option[MaybeScalaVersion] = None,