Add support for jvm using directive

modules/build/src/main/scala/scala/build/preprocessing/ScalaPreprocessor.scala

@@ -49,6 +49,7 @@ case object ScalaPreprocessor extends Preprocessor {
     UsingJavacOptionsDirectiveHandler,
     UsingJavaOptionsDirectiveHandler,
     UsingJavaPropsDirectiveHandler,
+    UsingJvmDirectiveHandler,
     UsingMainClassDirectiveHandler,
     UsingOptionDirectiveHandler,
     UsingPackagingDirectiveHandler,

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

@@ -7,7 +7,7 @@ import java.io.File
 
 import scala.build.internal.{Constants, ExternalBinaryParams, FetchExternalBinary, Runner}
 import scala.build.options.BuildOptions
-import scala.build.{Build, BuildThreads, Logger}
+import scala.build.{Build, BuildThreads, Logger, Positioned}
 import scala.cli.CurrentParams
 import scala.cli.commands.publish.ConfigUtil.*
 import scala.cli.commands.util.CommonOps.SharedDirectoriesOptionsOps
@@ -51,7 +51,7 @@ object Metabrowse extends ScalaCommand[MetabrowseOptions] {
           fetchSources = Some(true)
         ),
         javaOptions = baseOptions.javaOptions.copy(
-          jvmIdOpt = baseOptions.javaOptions.jvmIdOpt.orElse(Some("8"))
+          jvmIdOpt = baseOptions.javaOptions.jvmIdOpt.orElse(Some(Positioned.none("8")))
         )
       )
     }

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

@@ -71,7 +71,7 @@ object Run extends ScalaCommand[RunOptions] with BuildCommandHelpers {
         jvmIdOpt = baseOptions.javaOptions.jvmIdOpt.orElse {
           runMode(options) match {
             case _: RunMode.Spark | RunMode.HadoopJar =>
-              Some("8")
+              Some(Positioned.none("8"))
             case RunMode.Default => None
           }
         }

modules/cli/src/main/scala/scala/cli/commands/util/JvmUtils.scala

@@ -48,7 +48,7 @@ object JvmUtils {
       javaHomeOpt = javaHome.filter(_.nonEmpty).map(v =>
         Positioned(Seq(Position.CommandLine("--java-home")), os.Path(v, Os.pwd))
       ),
-      jvmIdOpt = jvm.filter(_.nonEmpty),
+      jvmIdOpt = jvm.filter(_.nonEmpty).map(Positioned.commandLine),
       jvmIndexOpt = jvmIndex.filter(_.nonEmpty),
       jvmIndexOs = jvmIndexOs.map(_.trim).filter(_.nonEmpty),
       jvmIndexArch = jvmIndexArch.map(_.trim).filter(_.nonEmpty),

modules/cli/src/main/scala/scala/cli/launcher/LauncherCli.scala

@@ -52,7 +52,7 @@ object LauncherCli {
 
     val buildOptions = BuildOptions(
       javaOptions = JavaOptions(
-        jvmIdOpt = Some(OsLibc.baseDefaultJvm(OsLibc.jvmIndexOs, "17"))
+        jvmIdOpt = Some(OsLibc.baseDefaultJvm(OsLibc.jvmIndexOs, "17")).map(Positioned.none)
       )
     )
 

modules/cli/src/main/scala/scala/cli/packaging/NativeImage.scala

@@ -4,7 +4,7 @@ import java.io.File
 
 import scala.annotation.tailrec
 import scala.build.internal.{ManifestJar, Runner}
-import scala.build.{Build, Logger}
+import scala.build.{Build, Logger, Positioned}
 import scala.cli.errors.GraalVMNativeImageError
 import scala.cli.graal.{BytecodeProcessor, TempCache}
 import scala.cli.internal.CachedBinary
@@ -171,7 +171,7 @@ object NativeImage {
     val jvmId = build.options.notForBloopOptions.packageOptions.nativeImageOptions.jvmId
     val options = build.options.copy(
       javaOptions = build.options.javaOptions.copy(
-        jvmIdOpt = Some(jvmId)
+        jvmIdOpt = Some(Positioned.none(jvmId))
       )
     )
 

modules/directives/src/main/scala/scala/build/preprocessing/directives/UsingJvmDirectiveHandler.scala

@@ -0,0 +1,43 @@
+package scala.build.preprocessing.directives
+
+import scala.build.Logger
+import scala.build.errors.BuildException
+import scala.build.options.{BuildOptions, JavaOptions, MaybeScalaVersion, ScalaOptions}
+import scala.build.preprocessing.directives.UsingMainClassDirectiveHandler.checkIfValuesAreExpected
+
+case object UsingJvmDirectiveHandler extends UsingDirectiveHandler {
+  def name = "JVM version"
+
+  def description = "Use a specific JVM, such as `14`, `adopt:11`, or `graalvm:21`, or `system`"
+
+  def usage = "//> using jvm _value_"
+
+  override def usageMd = "`//> using jvm` _value_"
+
+  override def examples = Seq(
+    "//> using jvm \"11\"",
+    "//> using jvm \"adopt:11\"",
+    "//> using jvm \"graalvm:21\""
+  )
+
+  def keys = Seq("jvm")
+
+  override def isRestricted = false
+
+  def handleValues(
+    scopedDirective: ScopedDirective,
+    logger: Logger
+  ): Either[BuildException, ProcessedUsingDirective] =
+    checkIfValuesAreExpected(scopedDirective).map { groupedValues =>
+      val jvmIdOpts = groupedValues.scopedStringValues.map(_.positioned)
+      val options = BuildOptions(
+        javaOptions = JavaOptions(
+          jvmIdOpt = jvmIdOpts.headOption
+        )
+      )
+      ProcessedDirective(Some(options), Seq.empty)
+    }
+
+  override def getValueNumberBounds(key: String) = UsingDirectiveValueNumberBounds(1, 1)
+
+}

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

@@ -1671,10 +1671,23 @@ abstract class RunTestDefinitions(val scalaVersionOpt: Option[String])
 
   test("Runs with JVM 8") {
     val inputs =
-      TestInputs(os.rel / "run.scala" -> """object Main extends App { println("hello")}""")
+      TestInputs(
+        os.rel / "run.scala" -> """object Main extends App { println(System.getProperty("java.version"))}"""
+      )
     inputs.fromRoot { root =>
       val p = os.proc(TestUtil.cli, "run.scala", "--jvm", "8").call(cwd = root)
-      expect(p.out.trim() == "hello")
+      expect(p.out.trim().startsWith("1.8"))
+    }
+  }
+
+  test("Runs with JVM 8 with using directive") {
+    val inputs =
+      TestInputs(os.rel / "run.scala" ->
+        """//> using jvm "8"
+          |object Main extends App { println(System.getProperty("java.version"))}""".stripMargin)
+    inputs.fromRoot { root =>
+      val p = os.proc(TestUtil.cli, "run.scala").call(cwd = root)
+      expect(p.out.trim().startsWith("1.8"))
     }
   }
 

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

@@ -19,7 +19,7 @@ import scala.util.control.NonFatal
   */
 final case class JavaOptions(
   javaHomeOpt: Option[Positioned[os.Path]] = None,
-  jvmIdOpt: Option[String] = None,
+  jvmIdOpt: Option[Positioned[String]] = None,
   jvmIndexOpt: Option[String] = None,
   jvmIndexOs: Option[String] = None,
   jvmIndexArch: Option[String] = None,
@@ -74,7 +74,7 @@ final case class JavaOptions(
         else None
       }
       .orElse {
-        jvmIdOpt.map { jvmId =>
+        jvmIdOpt.map(_.value).map { jvmId =>
           implicit val ec: ExecutionContextExecutorService = cache.ec
           cache.logger.use {
             val enforceLiberica =

website/docs/commands/run.md

@@ -60,6 +60,11 @@ scala-cli Hello.scala hi.sc --main-class hi_sc
 scala-cli Hello.scala --jvm adopt:14
 ```
 
+You can also specify custom JVM with the using directive `//> using jvm`:
+```scala
+//> using jvm "adopt:14"
+```
+
 JVMs are [managed by coursier](https://get-coursier.io/docs/cli-java#managed-jvms), and are read from the [coursier JVM index](https://github.com/coursier/jvm-index).
 (New JVM versions are automatically checked daily, and updates for those are - manually - merged
 swiftly.)

website/docs/reference/directives.md

@@ -64,6 +64,19 @@ Add dependencies
 
 `//> using lib "tabby:tabby:0.2.3,url=https://github.com/bjornregnell/tabby/releases/download/v0.2.3/tabby_3-0.2.3.jar"`
 
+### JVM version
+
+Use a specific JVM, such as `14`, `adopt:11`, or `graalvm:21`, or `system`
+
+`//> using jvm` _value_
+
+#### Examples
+`//> using jvm "11"`
+
+`//> using jvm "adopt:11"`
+
+`//> using jvm "graalvm:21"`
+
 ### Java home
 
 Sets Java home used to run your application or tests

website/docs/reference/scala-command/directives.md

@@ -64,6 +64,19 @@ Add dependencies
 
 `//> using lib "tabby:tabby:0.2.3,url=https://github.com/bjornregnell/tabby/releases/download/v0.2.3/tabby_3-0.2.3.jar"`
 
+### JVM version
+
+Use a specific JVM, such as `14`, `adopt:11`, or `graalvm:21`, or `system`
+
+`//> using jvm` _value_
+
+#### Examples
+`//> using jvm "11"`
+
+`//> using jvm "adopt:11"`
+
+`//> using jvm "graalvm:21"`
+
 ### Java home
 
 Sets Java home used to run your application or tests