Explicitly pass built compiler-bridge jar locations from the build system into Mill as JVM properties.

This makes the dependency between the compiler-bridge jar and the Mill executable explicit, allowing us to swap out the locations compiler-bridge jars (which end up in different places, depending on whether you're building with SBT or Mill) or eventually making them load from Maven Central in a "release" Mill executable

Since Mill (and uTest) both do not support SBT-style test arguments, we need to use `forkTest` instead of `test` to run the Mill tests passing the compiler-jar locations as JVM props. This necessitated some fixes to make `forkTest` behave properly

5 files changed, 80 insertions, 45 deletions

diff --git a/build.sbt b/build.sbt
index 1177cf26..1dc993bf 100644
--- a/build.sbt
+++ b/build.sbt
@@ -8,19 +8,6 @@ val sharedSettings = Seq(
   parallelExecution in Test := false,
   test in assembly := {},
 
-  assemblyOption in assembly := (assemblyOption in assembly).value.copy(
-    prependShellScript = Some(
-      // G1 Garbage Collector is awesome https://github.com/lihaoyi/Ammonite/issues/216
-      Seq("#!/usr/bin/env sh", """exec java -cp "$0" mill.Main "$@" """)
-    )
-  ),
-  assembly in Test := {
-    val dest = target.value/"mill"
-    IO.copyFile(assembly.value, dest)
-    import sys.process._
-    Seq("chmod", "+x", dest.getAbsolutePath).!
-    dest
-  },
   libraryDependencies += "com.lihaoyi" %% "acyclic" % "0.1.7" % "provided",
   scalacOptions += "-P:acyclic:force",
   autoCompilerPlugins := true,
@@ -97,26 +84,39 @@ lazy val core = project
     )
   )
 
+val bridgeProps = Def.task{
+  val mapping = Map(
+    "MILL_COMPILER_BRIDGE_2_10_6" -> (packageBin in (bridge2_10_6, Compile)).value.absolutePath,
+    "MILL_COMPILER_BRIDGE_2_11_8" -> (packageBin in (bridge2_11_8, Compile)).value.absolutePath,
+    "MILL_COMPILER_BRIDGE_2_11_11" -> (packageBin in (bridge2_11_11, Compile)).value.absolutePath,
+    "MILL_COMPILER_BRIDGE_2_12_3" -> (packageBin in (bridge2_12_3, Compile)).value.absolutePath,
+    "MILL_COMPILER_BRIDGE_2_12_4" -> (packageBin in (bridge2_12_4, Compile)).value.absolutePath
+  )
+  for((k, v) <- mapping) yield s"-D$k=$v"
+}
 lazy val scalaplugin = project
   .dependsOn(core % "compile->compile;test->test")
   .settings(
     sharedSettings,
     name := "mill-scalaplugin",
-    (compile in Test) := {
-      val a = (packageBin in (bridge2_10_6, Compile)).value
-      val b = (packageBin in (bridge2_11_8, Compile)).value
-//      val c = (packageBin in (bridge2_11_9, Compile)).value
-//      val d = (packageBin in (bridge2_11_10, Compile)).value
-      val e = (packageBin in (bridge2_11_11, Compile)).value
-//      val f = (packageBin in (bridge2_12_0, Compile)).value
-//      val g = (packageBin in (bridge2_12_1, Compile)).value
-//      val h = (packageBin in (bridge2_12_2, Compile)).value
-      val i = (packageBin in (bridge2_12_3, Compile)).value
-      val j = (packageBin in (bridge2_12_4, Compile)).value
-      (compile in Test).value
+    fork in Test := true,
+    baseDirectory in (Test, test) := (baseDirectory in (Test, test)).value / "..",
+    javaOptions in (Test, test) := bridgeProps.value.toSeq,
+    assemblyOption in assembly := {
+      (assemblyOption in assembly).value.copy(
+        prependShellScript = Some(
+          Seq(
+            "#!/usr/bin/env sh",
+            s"""exec java ${bridgeProps.value.mkString(" ")} -cp "$$0" mill.Main "$$@" """
+          )
+        )
+      )
     },
     assembly in Test := {
-      (compile in Test).value
-      (assembly in Test).value
+      val dest = target.value/"mill"
+      IO.copyFile(assembly.value, dest)
+      import sys.process._
+      Seq("chmod", "+x", dest.getAbsolutePath).!
+      dest
     }
   )
diff --git a/build.sc b/build.sc
index 7b261892..5d581364 100755
--- a/build.sc
+++ b/build.sc
@@ -5,7 +5,10 @@ import mill.scalaplugin._
 trait MillModule extends ScalaModule{ outer =>
   def scalaVersion = "2.12.4"
   override def sources = basePath/'src/'main/'scala
+  def testArgs = T{ Seq.empty[String] }
   object test extends this.Tests{
+    override def defaultCommandName() = "forkTest"
+    override def forkArgs = T{ testArgs() }
     override def projectDeps =
       if (this == Core.test) Seq(Core)
       else Seq(outer, Core.test)
@@ -80,14 +83,20 @@ object ScalaPlugin extends MillModule {
   override def projectDeps = Seq(Core)
   def basePath = pwd / 'scalaplugin
   override def compile = T.persistent[mill.eval.PathRef]{
-    bridges("2.10.6").compile()
-    bridges("2.11.8").compile()
-    bridges("2.11.11").compile()
-    bridges("2.12.3").compile()
-    bridges("2.12.4").compile()
     super.compile()
   }
+  override def testArgs = T{
+    val mapping = Map(
+      "MILL_COMPILER_BRIDGE_2_10_6" -> bridges("2.10.6").compile().path,
+      "MILL_COMPILER_BRIDGE_2_11_8" -> bridges("2.11.8").compile().path,
+      "MILL_COMPILER_BRIDGE_2_11_11" -> bridges("2.11.11").compile().path,
+      "MILL_COMPILER_BRIDGE_2_12_3" -> bridges("2.12.3").compile().path,
+      "MILL_COMPILER_BRIDGE_2_12_4" -> bridges("2.12.4").compile().path,
+    )
+    for((k, v) <- mapping.toSeq) yield s"-D$k=$v"
+  }
+
   override def prependShellScript =
     "#!/usr/bin/env sh\n" +
-    """exec java $JAVA_OPTS -cp "$0" mill.Main "$@" """
+    s"""exec java ${testArgs().mkString(" ")} $$JAVA_OPTS -cp "$$0" mill.Main "$$@" """
 }
diff --git a/core/src/main/scala/mill/modules/Jvm.scala b/core/src/main/scala/mill/modules/Jvm.scala
index 43382b8d..ddc8b427 100644
--- a/core/src/main/scala/mill/modules/Jvm.scala
+++ b/core/src/main/scala/mill/modules/Jvm.scala
@@ -1,6 +1,7 @@
 package mill.modules
 
 import java.io.FileOutputStream
+import java.net.URLClassLoader
 import java.nio.file.attribute.PosixFilePermission
 import java.util.jar.{JarEntry, JarFile, JarOutputStream}
 
@@ -14,16 +15,35 @@ import scala.collection.mutable
 
 
 object Jvm {
-
+  def gatherClassloaderJars(): Seq[Path] = {
+    val allJars = collection.mutable.Buffer.empty[Path]
+    var currentClassloader = Thread.currentThread().getContextClassLoader
+    while(currentClassloader != null){
+      currentClassloader match{
+        case u: URLClassLoader => allJars.appendAll(u.getURLs.map(x => Path(x.getFile)))
+        case _ =>
+      }
+      currentClassloader = currentClassloader.getParent
+    }
+    allJars
+  }
   def subprocess(mainClass: String,
                  classPath: Seq[Path],
+                 jvmOptions: Seq[String] = Seq.empty,
                  options: Seq[String] = Seq.empty,
                  workingDir: Path = ammonite.ops.pwd)
                 (implicit ctx: Ctx) = {
+
+    val commandArgs =
+      Vector("java") ++
+      jvmOptions ++
+      Vector("-cp", classPath.mkString(":"), mainClass) ++
+      options
+
     val proc =
       new java.lang.ProcessBuilder()
         .directory(workingDir.toIO)
-        .command(Vector("java", "-cp", classPath.mkString(":"), mainClass) ++ options:_*)
+        .command(commandArgs:_*)
         .redirectOutput(ProcessBuilder.Redirect.PIPE)
         .redirectError(ProcessBuilder.Redirect.PIPE)
         .start()
diff --git a/scalaplugin/src/main/scala/mill/scalaplugin/ScalaModule.scala b/scalaplugin/src/main/scala/mill/scalaplugin/ScalaModule.scala
index 49d9660f..0686f131 100644
--- a/scalaplugin/src/main/scala/mill/scalaplugin/ScalaModule.scala
+++ b/scalaplugin/src/main/scala/mill/scalaplugin/ScalaModule.scala
@@ -34,6 +34,7 @@ object ScalaModule{
   }
 
   var scalaInstanceCache = Option.empty[(Long, ScalaInstance)]
+
   def compileScala(scalaVersion: String,
                    sources: Seq[Path],
                    compileClasspath: Seq[Path],
@@ -52,11 +53,10 @@ object ScalaModule{
     }
 
     val compilerJars = compilerClasspath.toArray.map(_.toIO)
-    def binaryScalaVersion = scalaVersion.split('.').dropRight(1).mkString(".")
-    val compilerBridgeJar = new java.io.File(
-      s"bridge/${scalaVersion.replace('.', '_')}/target/scala-$binaryScalaVersion/mill-bridge_$scalaVersion-0.1-SNAPSHOT.jar"
-//      s"out/bridges/$scalaVersion/compile/classes"
-    )
+    val compilerBridgeKey = "MILL_COMPILER_BRIDGE_"+scalaVersion.replace('.', '_')
+    val compilerBridgePath = sys.props(compilerBridgeKey)
+    assert(compilerBridgePath != null, "Cannot find compiler bridge " + compilerBridgeKey)
+    val compilerBridgeJar = new java.io.File(compilerBridgePath)
 
     val classloaderSig = compilerClasspath.map(p => p.toString().hashCode + p.mtime.toMillis).sum
 
@@ -184,14 +184,15 @@ trait TestScalaModule extends ScalaModule with TaskModule {
   def testFramework: T[String]
 
   def forkWorkingDir = ammonite.ops.pwd
+  def forkArgs = T{ Seq.empty[String] }
   def forkTest(args: String*) = T.command{
     val outputPath = tmp.dir()/"out.json"
+
     Jvm.subprocess(
-      "mill.scalaplugin.TestRunner",
-      getClass.getClassLoader.asInstanceOf[URLClassLoader].getURLs.toList.map(
-        u => Path(new java.io.File(u.toURI))
-      ),
-      Seq(
+      mainClass = "mill.scalaplugin.TestRunner",
+      classPath = Jvm.gatherClassloaderJars(),
+      jvmOptions = forkArgs(),
+      options = Seq(
         testFramework(),
         (runDepClasspath().map(_.path) :+ compile().path).mkString(" "),
         Seq(compile().path).mkString(" "),
diff --git a/scalaplugin/src/main/scala/mill/scalaplugin/TestRunner.scala b/scalaplugin/src/main/scala/mill/scalaplugin/TestRunner.scala
index 43e15974..bc36d9c7 100644
--- a/scalaplugin/src/main/scala/mill/scalaplugin/TestRunner.scala
+++ b/scalaplugin/src/main/scala/mill/scalaplugin/TestRunner.scala
@@ -50,6 +50,11 @@ object TestRunner {
     })
     val outputPath = args(4)
     ammonite.ops.write(Path(outputPath), upickle.default.write(result))
+
+    // Tests are over, kill the JVM whether or not anyone's threads are still running
+    // Always return 0, even if tests fail. The caller can pick up the detailed test
+    // results from the outputPath
+    System.exit(0)
   }
   def apply(frameworkName: String,
             entireClasspath: Seq[Path],