Extract used Java versions to constants

build.sc

@@ -1,7 +1,7 @@
 import $ivy.`com.lihaoyi::mill-contrib-bloop:$MILL_VERSION`
 import $ivy.`io.get-coursier::coursier-launcher:2.1.10`
 import $ivy.`io.github.alexarchambault.mill::mill-native-image-upload:0.1.25`
-import $file.project.deps, deps.{Deps, Docker, InternalDeps, Scala, TestDeps}
+import $file.project.deps, deps.{Deps, Docker, InternalDeps, Java, Scala, TestDeps}
 import $file.project.publish, publish.{ghOrg, ghName, ScalaCliPublishModule, organization}
 import $file.project.settings, settings.{
   CliLaunchers,
@@ -459,6 +459,10 @@ trait Core extends ScalaCliCrossSbtModule
          |  def typelevelToolkitDefaultVersion = "${Deps.typelevelToolkitVersion}"
          |  def typelevelToolkitMaxScalaNative = "${Deps.Versions.maxScalaNativeForTypelevelToolkit}"
          |
+         |  def minimumBloopJavaVersion = ${Java.minimumBloopJava}
+         |  def minimumInternalJavaVersion = ${Java.minimumInternalJava}
+         |  def defaultJavaVersion = ${Java.defaultJava}
+         |
          |  def defaultScalaVersion = "${Scala.defaultUser}"
          |  def defaultScala212Version = "${Scala.scala212}"
          |  def defaultScala213Version = "${Scala.scala213}"
@@ -809,6 +813,8 @@ trait Cli extends CrossSbtModule with ProtoBuildModule with CliLaunchers
          |/** Build-time constants. Generated by mill. */
          |object Constants {
          |  def defaultScalaVersion = "${Scala.defaultUser}"
+         |  def defaultJavaVersion = ${Java.defaultJava}
+         |  def minimumBloopJavaVersion = ${Java.minimumBloopJava}
          |  def scalaJsVersion = "${Scala.scalaJs}"
          |  def scalaJsCliVersion = "${Scala.scalaJsCli}"
          |  def scalaNativeVersion = "${Deps.nativeTools.dep.version}"

modules/cli/src/main/scala/scala/cli/ScalaCli.scala

@@ -138,14 +138,15 @@ object ScalaCli {
         }
 
         e match {
-          case _: UnsupportedClassVersionError if javaMajorVersion < 17 =>
-            warnRequiresJava17()
+          case _: UnsupportedClassVersionError
+              if javaMajorVersion < Constants.minimumBloopJavaVersion =>
+            warnRequiresMinimumBloopJava()
           case _: NoClassDefFoundError
               if isJava17ClassName(e.getMessage) &&
               CurrentParams.verbosity <= 1 &&
-              javaMajorVersion < 16 =>
+              javaMajorVersion < Constants.minimumInternalJavaVersion =>
             // Actually Java >= 16 here, but let's recommend a LTS version…
-            warnRequiresJava17()
+            warnRequiresMinimumBloopJava()
           case _: FailedToStartServerException =>
             System.err.println(
               s"""Running
@@ -169,9 +170,9 @@ object ScalaCli {
         else sys.exit(1)
     }
 
-  private def warnRequiresJava17(): Unit =
+  private def warnRequiresMinimumBloopJava(): Unit =
     System.err.println(
-      s"Java >= 17 is required to run $fullRunnerName (found Java $javaMajorVersion)"
+      s"Java >= ${Constants.minimumBloopJavaVersion} is required to run $fullRunnerName (found Java $javaMajorVersion)"
     )
 
   def loadJavaProperties(cwd: os.Path) = {
@@ -250,7 +251,7 @@ object ScalaCli {
             val newArgs = powerArgs ++ finalScalaRunnerArgs ++ args0
             LauncherCli.runAndExit(ver, launcherOpts, newArgs)
           case _ if
-                javaMajorVersion < 17
+                javaMajorVersion < Constants.minimumBloopJavaVersion
                 && sys.props.get("scala-cli.kind").exists(_.startsWith("jvm")) =>
             JavaLauncherCli.runAndExit(args)
           case None =>

modules/cli/src/main/scala/scala/cli/commands/bloop/Bloop.scala

@@ -4,7 +4,7 @@ import bloop.rifle.internal.Operations
 import bloop.rifle.{BloopRifle, BloopRifleConfig, BloopThreads}
 import caseapp.core.RemainingArgs
 
-import scala.build.internal.OsLibc
+import scala.build.internal.{Constants, OsLibc}
 import scala.build.{Directories, Logger}
 import scala.cli.CurrentParams
 import scala.cli.commands.ScalaCommand
@@ -38,7 +38,7 @@ object Bloop extends ScalaCommand[BloopOptions] {
     val javaHomeInfo = opts.compilationServer.bloopJvm
       .map(JvmUtils.downloadJvm(_, options))
       .getOrElse {
-        JvmUtils.getJavaCmdVersionOrHigher(17, options)
+        JvmUtils.getJavaCmdVersionOrHigher(Constants.minimumBloopJavaVersion, options)
       }.orExit(logger)
 
     opts.compilationServer.bloopRifleConfig(

modules/cli/src/main/scala/scala/cli/commands/new/New.scala

@@ -39,7 +39,7 @@ object New extends ScalaCommand[NewOptions] {
 
     val buildOptions = BuildOptions(
       javaOptions = JavaOptions(
-        jvmIdOpt = Some(OsLibc.baseDefaultJvm(OsLibc.jvmIndexOs, "17")).map(Positioned.none)
+        jvmIdOpt = Some(OsLibc.defaultJvm(OsLibc.jvmIndexOs)).map(Positioned.none)
       )
     )
 

modules/cli/src/main/scala/scala/cli/commands/shared/SharedCompilationServerOptions.scala

@@ -6,7 +6,7 @@ import caseapp.*
 import com.github.plokhotnyuk.jsoniter_scala.core.*
 import com.github.plokhotnyuk.jsoniter_scala.macros.*
 import coursier.cache.FileCache
-import coursier.core.{Version => Ver}
+import coursier.core.Version as Ver
 import coursier.util.Task
 
 import java.io.File
@@ -15,6 +15,7 @@ import java.util.Random
 
 import scala.build.internal.Util
 import scala.build.{Bloop, Logger, Os}
+import scala.cli.commands.Constants
 import scala.cli.commands.bloop.BloopJson
 import scala.cli.commands.shared.*
 import scala.cli.internal.Pid
@@ -86,7 +87,7 @@ final case class SharedCompilationServerOptions(
     bloopGlobalOptionsFile: Option[String] = None,
 
   @Group(HelpGroup.CompilationServer.toString)
-  @HelpMessage("JVM to use to start Bloop (e.g. 'system|11', 'temurin:17', …)")
+  @HelpMessage(s"JVM to use to start Bloop (e.g. 'system|${Constants.minimumBloopJavaVersion}', 'temurin:21', …)")
   @Hidden
     bloopJvm: Option[String] = None,
 
@@ -276,7 +277,7 @@ final case class SharedCompilationServerOptions(
       javaOpts =
         (if (bloopDefaultJavaOpts) baseConfig.javaOpts
          else Nil) ++ bloopJavaOpt ++ bloopDefaultJvmOptions(logger).getOrElse(Nil),
-      minimumBloopJvm = javaV.getOrElse(17),
+      minimumBloopJvm = javaV.getOrElse(Constants.minimumBloopJavaVersion),
       retainedBloopVersion = retainedBloopVersion
     )
   }

modules/cli/src/main/scala/scala/cli/commands/shared/SharedOptions.scala

@@ -568,7 +568,7 @@ final case class SharedOptions(
       .orElse {
         for (javaHome <- options.javaHomeLocationOpt()) yield {
           val (javaHomeVersion, javaHomeCmd) = OsLibc.javaHomeVersion(javaHome.value)
-          if (javaHomeVersion >= 17)
+          if (javaHomeVersion >= Constants.minimumBloopJavaVersion)
             BuildOptions.JavaHomeInfo(javaHome.value, javaHomeCmd, javaHomeVersion)
           else defaultJvmHome
         }

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

@@ -295,9 +295,8 @@ final case class MavenProjectDescriptor(
     sourcesTest: Sources
   ): Either[BuildException, MavenProject] = {
     val jdk =
-      optionsMain.javaOptions.jvmIdOpt.map(_.value).getOrElse(
-        "17"
-      ) // todo: get from constants for default jdk
+      optionsMain.javaOptions.jvmIdOpt.map(_.value)
+        .getOrElse(Constants.defaultJavaVersion.toString)
     val projectChunks = Seq(
       sources(sourcesMain, sourcesTest),
       javaOptionsSettings(optionsMain),

modules/cli/src/main/scala/scala/cli/javaLauncher/JavaLauncherCli.scala

@@ -19,7 +19,7 @@ object JavaLauncherCli {
 
     val buildOptions = BuildOptions(
       javaOptions = JavaOptions(
-        jvmIdOpt = Some(OsLibc.baseDefaultJvm(OsLibc.jvmIndexOs, "17")).map(Positioned.none)
+        jvmIdOpt = Some(OsLibc.defaultJvm(OsLibc.jvmIndexOs)).map(Positioned.none)
       )
     )
     val launcherKind = sys.props.get("scala-cli.kind") match {

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")).map(Positioned.none)
+        jvmIdOpt = Some(OsLibc.defaultJvm(OsLibc.jvmIndexOs)).map(Positioned.none)
       )
     )
 

modules/core/src/main/scala/scala/build/internals/OsLibc.scala

@@ -61,20 +61,18 @@ object OsLibc {
     else default
   }
 
-  private def defaultJvmVersion = "17"
-
   def baseDefaultJvm(os: String, jvmVersion: String): String = {
-    def java17OrHigher = Try(jvmVersion.takeWhile(_.isDigit).toInt)
+    def bloomMinimumJavaOrHigher = Try(jvmVersion.takeWhile(_.isDigit).toInt)
       .toOption
-      .forall(_ >= 17)
+      .forall(_ >= Constants.minimumBloopJavaVersion)
     if (os == "linux-musl") s"liberica:$jvmVersion" // zulu could work too
-    else if (java17OrHigher) s"temurin:$jvmVersion"
+    else if (bloomMinimumJavaOrHigher) s"temurin:$jvmVersion"
     else if (Os.isArmArchitecture) s"zulu:$jvmVersion" // adopt doesn't support Java 8 on macOS arm
     else s"temurin:$jvmVersion"
   }
 
   def defaultJvm(os: String): String =
-    baseDefaultJvm(os, defaultJvmVersion)
+    baseDefaultJvm(os, Constants.defaultJavaVersion.toString)
 
   def javaVersion(javaCmd: String): Int = {
     val javaVersionOutput = os.proc(javaCmd, "-version").call(

project/deps.sc

@@ -1,4 +1,6 @@
-import mill._, scalalib._
+import Deps.Versions
+import mill._
+import scalalib._
 
 object Scala {
   def scala212        = "2.12.19"
@@ -69,6 +71,12 @@ object Scala {
   }
 }
 
+object Java {
+  def minimumBloopJava    = 17
+  def minimumInternalJava = 16
+  def defaultJava         = minimumBloopJava
+}
+
 // Dependencies used in integration test fixtures
 object TestDeps {
   def pprint           = Deps.pprint
@@ -108,7 +116,7 @@ object Deps {
     def maxScalaNativeForMillExport       = scalaNative04
     def scalaPackager                     = "0.1.29"
     def signingCli                        = "0.2.3"
-    def signingCliJvmVersion              = 17
+    def signingCliJvmVersion              = Java.defaultJava
     def javaSemanticdb                    = "0.10.0"
     def javaClassName                     = "0.1.3"
     def bloop                             = "2.0.0-RC1"
@@ -233,7 +241,7 @@ object Deps {
 }
 
 def graalVmVersion     = "22.3.1"
-def graalVmJavaVersion = 17
+def graalVmJavaVersion = Java.defaultJava
 def graalVmJvmId       = s"graalvm-java$graalVmJavaVersion:$graalVmVersion"
 
 def csDockerVersion = Deps.Versions.coursierCli

website/docs/reference/cli-options.md

@@ -129,7 +129,7 @@ Bloop global options file
 ### `--bloop-jvm`
 
 [Internal]
-JVM to use to start Bloop (e.g. 'system|11', 'temurin:17', …)
+JVM to use to start Bloop (e.g. 'system|17', 'temurin:21', …)
 
 ### `--bloop-working-dir`
 

website/docs/reference/scala-command/cli-options.md

@@ -126,7 +126,7 @@ Bloop global options file
 
 `IMPLEMENTATION specific` per Scala Runner specification
 
-JVM to use to start Bloop (e.g. 'system|11', 'temurin:17', …)
+JVM to use to start Bloop (e.g. 'system|17', 'temurin:21', …)
 
 ### `--bloop-working-dir`
 

website/docs/reference/scala-command/runner-specification.md

@@ -494,7 +494,7 @@ Bloop global options file
 
 **--bloop-jvm**
 
-JVM to use to start Bloop (e.g. 'system|11', 'temurin:17', …)
+JVM to use to start Bloop (e.g. 'system|17', 'temurin:21', …)
 
 **--bloop-working-dir**
 
@@ -1257,7 +1257,7 @@ Bloop global options file
 
 **--bloop-jvm**
 
-JVM to use to start Bloop (e.g. 'system|11', 'temurin:17', …)
+JVM to use to start Bloop (e.g. 'system|17', 'temurin:21', …)
 
 **--bloop-working-dir**
 
@@ -1852,7 +1852,7 @@ Bloop global options file
 
 **--bloop-jvm**
 
-JVM to use to start Bloop (e.g. 'system|11', 'temurin:17', …)
+JVM to use to start Bloop (e.g. 'system|17', 'temurin:21', …)
 
 **--bloop-working-dir**
 
@@ -2471,7 +2471,7 @@ Bloop global options file
 
 **--bloop-jvm**
 
-JVM to use to start Bloop (e.g. 'system|11', 'temurin:17', …)
+JVM to use to start Bloop (e.g. 'system|17', 'temurin:21', …)
 
 **--bloop-working-dir**
 
@@ -3099,7 +3099,7 @@ Bloop global options file
 
 **--bloop-jvm**
 
-JVM to use to start Bloop (e.g. 'system|11', 'temurin:17', …)
+JVM to use to start Bloop (e.g. 'system|17', 'temurin:21', …)
 
 **--bloop-working-dir**
 
@@ -3685,7 +3685,7 @@ Bloop global options file
 
 **--bloop-jvm**
 
-JVM to use to start Bloop (e.g. 'system|11', 'temurin:17', …)
+JVM to use to start Bloop (e.g. 'system|17', 'temurin:21', …)
 
 **--bloop-working-dir**
 
@@ -4346,7 +4346,7 @@ Bloop global options file
 
 **--bloop-jvm**
 
-JVM to use to start Bloop (e.g. 'system|11', 'temurin:17', …)
+JVM to use to start Bloop (e.g. 'system|17', 'temurin:21', …)
 
 **--bloop-working-dir**
 
@@ -5014,7 +5014,7 @@ Bloop global options file
 
 **--bloop-jvm**
 
-JVM to use to start Bloop (e.g. 'system|11', 'temurin:17', …)
+JVM to use to start Bloop (e.g. 'system|17', 'temurin:21', …)
 
 **--bloop-working-dir**
 
@@ -5947,7 +5947,7 @@ Bloop global options file
 
 **--bloop-jvm**
 
-JVM to use to start Bloop (e.g. 'system|11', 'temurin:17', …)
+JVM to use to start Bloop (e.g. 'system|17', 'temurin:21', …)
 
 **--bloop-working-dir**
 
@@ -6226,7 +6226,7 @@ Bloop global options file
 
 **--bloop-jvm**
 
-JVM to use to start Bloop (e.g. 'system|11', 'temurin:17', …)
+JVM to use to start Bloop (e.g. 'system|17', 'temurin:21', …)
 
 **--bloop-working-dir**