Make java home configurable per-module

build.mill

@@ -123,6 +123,7 @@ object Deps {
 
   val coursier = ivy"io.get-coursier::coursier:2.1.14"
   val coursierInterface = ivy"io.get-coursier:interface:1.0.19"
+  val coursierJvm = ivy"io.get-coursier::coursier-jvm:2.1.13"
 
   val cask = ivy"com.lihaoyi::cask:0.9.4"
   val castor = ivy"com.lihaoyi::castor:0.3.0"

contrib/jmh/src/mill/contrib/jmh/JmhModule.scala

@@ -43,7 +43,8 @@ trait JmhModule extends JavaModule {
         classPath = (runClasspath() ++ generatorDeps()).map(_.path) ++
           Seq(compileGeneratedSources().path, resources),
         mainArgs = args,
-        workingDir = T.ctx().dest
+        workingDir = T.ctx().dest,
+        javaHome = zincWorker().javaHome().map(_.path)
       )
     }
 
@@ -72,7 +73,6 @@ trait JmhModule extends JavaModule {
   def generateBenchmarkSources =
     Task {
       val dest = T.ctx().dest
-      val javacOpts = javacOptions().toSeq
       val sourcesDir = dest / "jmh_sources"
       val resourcesDir = dest / "jmh_resources"
 
@@ -90,7 +90,7 @@ trait JmhModule extends JavaModule {
           resourcesDir.toString,
           "default"
         ),
-        jvmArgs = javacOpts
+        javaHome = zincWorker().javaHome().map(_.path)
       )
 
       (sourcesDir, resourcesDir)

example/thirdparty/commons-io/build.mill

@@ -1,9 +1,14 @@
 package build
 import mill._, javalib._, publish._
+import mill.define.ModuleRef
 import $ivy.`com.lihaoyi::mill-contrib-jmh:$MILL_VERSION`
 import contrib.jmh.JmhModule
 
+object ZincWorkerJava11 extends ZincWorkerModule.ForJvm("temurin:1.11.0.24")
+
 object `package` extends RootModule with PublishModule with MavenModule {
+  override def zincWorker = ModuleRef(ZincWorkerJava11)
+  def javacOptions = Seq("-encoding", "UTF-8")
   def publishVersion = "2.17.0-SNAPSHOT"
 
   def pomSettings = PomSettings(
@@ -69,4 +74,4 @@ PathUtilsContentEqualsBenchmark.testCurrent_fileContentEquals_Blackhole    ss
 PathUtilsContentEqualsBenchmark.testProposal_contentEquals                 ss    5 ...
 PathUtilsContentEqualsBenchmark.testProposal_contentEquals_Blackhole       ss    5 ...
 
-*/
+*/

example/thirdparty/mockito/build.mill

@@ -1,5 +1,6 @@
 package build
 import mill._, javalib._
+import mill.define.ModuleRef
 
 object libraries{
 
@@ -36,7 +37,11 @@ object libraries{
   val groovy = ivy"org.codehaus.groovy:groovy:3.0.22"
 }
 
+object ZincWorkerJava11 extends ZincWorkerModule.ForJvm("temurin:1.11.0.24")
+
 trait MockitoModule extends MavenModule{
+  override def zincWorker = ModuleRef(ZincWorkerJava11)
+  def javacOptions = Seq("-encoding", "UTF-8")
   def testModuleDeps: Seq[JavaModule] = Nil
   def testIvyDeps: T[Agg[Dep]] = Agg.empty[Dep]
   def testRuntimeIvyDeps: T[Agg[Dep]] = Agg.empty[Dep]

main/package.mill

@@ -100,7 +100,16 @@ object `package` extends RootModule with build.MillStableScalaModule with BuildI
 
   object util extends build.MillStableScalaModule {
     def moduleDeps = Seq(api, client)
-    def ivyDeps = Agg(build.Deps.coursier, build.Deps.jline)
+    def ivyDeps = Agg(
+      build.Deps.coursier,
+      build.Deps.coursierJvm.exclude(
+        // coursier-jvm has an unused dependency on argonaut-shapeless and
+        // shapeless causes issues with the assembly task when the locale
+        // is not set properly https://github.com/sbt/sbt-assembly/issues/496
+        "com.github.alexarchambault" -> "argonaut-shapeless_6.3_2.13",
+      ),
+      build.Deps.jline
+    )
   }
 
   object define extends build.MillStableScalaModule {

main/util/src/mill/util/CoursierSupport.scala

@@ -5,13 +5,16 @@ import coursier.error.FetchError.DownloadingArtifacts
 import coursier.error.ResolutionError.CantDownloadModule
 import coursier.params.ResolutionParams
 import coursier.parse.RepositoryParser
+import coursier.jvm.{JvmCache, JvmIndex, JavaHome}
 import coursier.util.Task
 import coursier.{Artifacts, Classifier, Dependency, Repository, Resolution, Resolve, Type}
 import mill.api.Loose.Agg
 import mill.api.{Ctx, PathRef, Result}
 
 import scala.collection.mutable
 import scala.util.chaining.scalaUtilChainingOps
+import coursier.cache.ArchiveCache
+import scala.util.control.NonFatal
 
 trait CoursierSupport {
   import CoursierSupport._
@@ -164,6 +167,41 @@ trait CoursierSupport {
     (deps0, res.getOrThrow)
   }
 
+  def jvmIndex(
+      ctx: Option[mill.api.Ctx.Log] = None,
+      coursierCacheCustomizer: Option[FileCache[Task] => FileCache[Task]] = None
+  ): Result[JvmIndex] = {
+    val coursierCache0 = coursierCache(ctx, coursierCacheCustomizer)
+    JvmIndex.load().unsafeRun()(coursierCache0.ec)
+  }
+
+  /**
+   * Resolve java home using Coursier.
+   *
+   * The id string has format "$DISTRIBUTION:$VERSION". e.g. graalvm-community:23.0.0
+   */
+  def resolveJavaHome(
+      id: String,
+      ctx: Option[mill.api.Ctx.Log] = None,
+      coursierCacheCustomizer: Option[FileCache[Task] => FileCache[Task]] = None
+  ): Result[os.Path] = {
+    val coursierCache0 = coursierCache(ctx, coursierCacheCustomizer)
+    val jvmCache = JvmCache()
+      .withArchiveCache(
+        ArchiveCache().withCache(coursierCache0)
+      )
+      .withIndex(JvmIndex.load())
+    val javaHome = JavaHome()
+      .withCache(jvmCache)
+    try {
+      val file = javaHome.get(id).unsafeRun()(coursierCache0.ec)
+      Result.Success(os.Path(file))
+    } catch {
+      case NonFatal(error) =>
+        Result.Exception(error, new Result.OuterStack((new Exception).getStackTrace))
+    }
+  }
+
   def resolveDependenciesMetadataSafe(
       repositories: Seq[Repository],
       deps: IterableOnce[Dependency],

main/util/src/mill/util/Jvm.scala

@@ -25,11 +25,12 @@ object Jvm extends CoursierSupport {
       mainArgs: Seq[String] = Seq.empty,
       workingDir: os.Path = null,
       streamOut: Boolean = true,
-      check: Boolean = true
+      check: Boolean = true,
+      javaHome: Option[os.Path] = None
   )(implicit ctx: Ctx): CommandResult = {
 
     val commandArgs =
-      Vector(javaExe) ++
+      Vector(javaExe(javaHome)) ++
         jvmArgs ++
         Vector("-cp", classPath.iterator.mkString(java.io.File.pathSeparator), mainClass) ++
         mainArgs
@@ -65,9 +66,10 @@ object Jvm extends CoursierSupport {
   /**
    * Resolves a tool to a path under the currently used JDK (if known).
    */
-  def jdkTool(toolName: String): String = {
-    sys.props
-      .get("java.home")
+  def jdkTool(toolName: String, javaHome: Option[os.Path]): String = {
+    javaHome
+      .map(_.toString())
+      .orElse(sys.props.get("java.home"))
       .map(h =>
         if (isWin) new File(h, s"bin\\${toolName}.exe")
         else new File(h, s"bin/${toolName}")
@@ -77,7 +79,11 @@ object Jvm extends CoursierSupport {
 
   }
 
-  def javaExe: String = jdkTool("java")
+  def jdkTool(toolName: String): String = jdkTool(toolName, None)
+
+  def javaExe(javaHome: Option[os.Path]): String = jdkTool("java", javaHome)
+
+  def javaExe: String = javaExe(None)
 
   def defaultBackgroundOutputs(outputDir: os.Path): Option[(ProcessOutput, ProcessOutput)] =
     Some((outputDir / "stdout.log", outputDir / "stderr.log"))
@@ -107,7 +113,8 @@ object Jvm extends CoursierSupport {
       workingDir: os.Path = null,
       background: Boolean = false,
       useCpPassingJar: Boolean = false,
-      runBackgroundLogToConsole: Boolean = false
+      runBackgroundLogToConsole: Boolean = false,
+      javaHome: Option[os.Path] = None
   )(implicit ctx: Ctx): Unit = {
     runSubprocessWithBackgroundOutputs(
       mainClass,
@@ -119,7 +126,8 @@ object Jvm extends CoursierSupport {
       if (!background) None
       else if (runBackgroundLogToConsole) Some((os.Inherit, os.Inherit))
       else Jvm.defaultBackgroundOutputs(ctx.dest),
-      useCpPassingJar
+      useCpPassingJar,
+      javaHome
     )
   }
 
@@ -169,7 +177,8 @@ object Jvm extends CoursierSupport {
       mainArgs: Seq[String] = Seq.empty,
       workingDir: os.Path = null,
       backgroundOutputs: Option[Tuple2[ProcessOutput, ProcessOutput]] = None,
-      useCpPassingJar: Boolean = false
+      useCpPassingJar: Boolean = false,
+      javaHome: Option[os.Path] = None
   )(implicit ctx: Ctx): Unit = {
 
     val cp =
@@ -193,7 +202,7 @@ object Jvm extends CoursierSupport {
       Seq(mainClass)
     } else Seq.empty
     val args =
-      Vector(javaExe) ++
+      Vector(javaExe(javaHome)) ++
         jvmArgs ++
         cpArgument ++
         mainClassArgument ++
@@ -207,6 +216,29 @@ object Jvm extends CoursierSupport {
       runSubprocess(args, envArgs, workingDir)
   }
 
+  // bincompat shim
+  def runSubprocessWithBackgroundOutputs(
+      mainClass: String,
+      classPath: Agg[os.Path],
+      jvmArgs: Seq[String],
+      envArgs: Map[String, String],
+      mainArgs: Seq[String],
+      workingDir: os.Path,
+      backgroundOutputs: Option[Tuple2[ProcessOutput, ProcessOutput]],
+      useCpPassingJar: Boolean
+  )(implicit ctx: Ctx): Unit =
+    runSubprocessWithBackgroundOutputs(
+      mainClass,
+      classPath,
+      jvmArgs,
+      envArgs,
+      mainArgs,
+      workingDir,
+      backgroundOutputs,
+      useCpPassingJar,
+      None
+    )(ctx)
+
   /**
    * Runs a generic subprocess and waits for it to terminate.
    */

scalalib/src/mill/scalalib/CoursierModule.scala

@@ -32,6 +32,15 @@ trait CoursierModule extends mill.Module {
     Lib.depToDependencyJava(_: Dep)
   }
 
+  def resolveJavaHome(id: String): Task[PathRef] = Task.Anon {
+    val path = mill.util.Jvm.resolveJavaHome(
+      id = id,
+      coursierCacheCustomizer = coursierCacheCustomizer(),
+      ctx = Some(implicitly[mill.api.Ctx.Log])
+    ).getOrThrow
+    PathRef(path, quick = true)
+  }
+
   def defaultResolver: Task[CoursierModule.Resolver] = Task.Anon {
     new CoursierModule.Resolver(
       repositories = repositoriesTask(),

scalalib/src/mill/scalalib/JavaModule.scala

@@ -1071,14 +1071,18 @@ trait JavaModule
   )
 
   @internal
-  def bspJvmBuildTarget: JvmBuildTarget =
+  def bspJvmBuildTarget: Task[JvmBuildTarget] = Task.Anon {
     JvmBuildTarget(
-      javaHome = Option(System.getProperty("java.home")).map(p => BspUri(os.Path(p))),
+      javaHome = zincWorker()
+        .javaHome()
+        .map(p => BspUri(p.path))
+        .orElse(Option(System.getProperty("java.home")).map(p => BspUri(os.Path(p)))),
       javaVersion = Option(System.getProperty("java.version"))
     )
+  }
 
   @internal
   override def bspBuildTargetData: Task[Option[(String, AnyRef)]] = Task.Anon {
-    Some((JvmBuildTarget.dataKind, bspJvmBuildTarget))
+    Some((JvmBuildTarget.dataKind, bspJvmBuildTarget()))
   }
 }

scalalib/src/mill/scalalib/RunModule.scala

@@ -135,7 +135,8 @@ trait RunModule extends WithZincWorker {
       runClasspath().map(_.path),
       forkArgs(),
       forkEnv(),
-      runUseArgsFile()
+      runUseArgsFile(),
+      zincWorker().javaHome().map(_.path)
     )
   }
 
@@ -257,7 +258,8 @@ object RunModule {
       runClasspath: Seq[os.Path],
       forkArgs0: Seq[String],
       forkEnv0: Map[String, String],
-      useCpPassingJar0: Boolean
+      useCpPassingJar0: Boolean,
+      javaHome: Option[os.Path]
   ) extends Runner {
 
     def run(
@@ -283,7 +285,8 @@ object RunModule {
           case Some(b) => b
           case None => useCpPassingJar0
         },
-        runBackgroundLogToConsole = runBackgroundLogToConsole
+        runBackgroundLogToConsole = runBackgroundLogToConsole,
+        javaHome
       )
     }
   }

scalalib/src/mill/scalalib/ScalaModule.scala

@@ -592,7 +592,7 @@ trait ScalaModule extends JavaModule with TestModule.ScalaModuleBase { outer =>
         scalaBinaryVersion = ZincWorkerUtil.scalaBinaryVersion(scalaVersion()),
         platform = ScalaPlatform.JVM,
         jars = scalaCompilerClasspath().map(_.path.toNIO.toUri.toString).iterator.toSeq,
-        jvmBuildTarget = Some(bspJvmBuildTarget)
+        jvmBuildTarget = Some(bspJvmBuildTarget())
       )
     ))
   }

scalalib/src/mill/scalalib/TestModule.scala

@@ -200,7 +200,8 @@ trait TestModule
         forkEnv(),
         testSandboxWorkingDir(),
         forkWorkingDir(),
-        testReportXml()
+        testReportXml(),
+        zincWorker().javaHome().map(_.path)
       )
     }
 

scalalib/src/mill/scalalib/TestModuleUtil.scala

@@ -28,7 +28,8 @@ private[scalalib] object TestModuleUtil {
       forkEnv: Map[String, String],
       testSandboxWorkingDir: Boolean,
       forkWorkingDir: os.Path,
-      testReportXml: Option[String]
+      testReportXml: Option[String],
+      javaHome: Option[os.Path]
   )(implicit ctx: mill.api.Ctx) = {
 
     val (jvmArgs, props: Map[String, String]) = loadArgsAndProps(useArgsFile, forkArgs)
@@ -72,7 +73,8 @@ private[scalalib] object TestModuleUtil {
         envArgs = forkEnv ++ resourceEnv,
         mainArgs = Seq(testRunnerClasspathArg, argsFile.toString),
         workingDir = if (testSandboxWorkingDir) sandbox else forkWorkingDir,
-        useCpPassingJar = useArgsFile
+        useCpPassingJar = useArgsFile,
+        javaHome = javaHome
       )
 
       if (!os.exists(outputPath)) Left(s"Test reporting Failed: ${outputPath} does not exist")