Removing printlns and adding the test, DOH.

sbt/src/sbt-test/tests/scala-instance-classloader/build.sbt

@@ -0,0 +1,29 @@
+
+lazy val OtherScala = config("other-scala").hide
+
+configs(OtherScala)
+
+libraryDependencies += "org.scala-lang" % "scala-compiler" % "2.11.1" % OtherScala.name
+
+managedClasspath in OtherScala := Classpaths.managedJars(OtherScala, classpathTypes.value, update.value)
+
+// Hack in the scala instance
+scalaInstance := {
+  val rawJars = (managedClasspath in OtherScala).value.map(_.data)
+  val scalaHome = (target.value / "scala-home")
+  def removeVersion(name: String): String =
+    name.replaceAll("\\-2.11.1", "")
+  for(jar <- rawJars) {
+    val tjar = scalaHome / s"lib/${removeVersion(jar.getName)}"
+    IO.copyFile(jar, tjar)
+  }
+  IO.listFiles(scalaHome).foreach(f => System.err.println(s" * $f}"))
+  ScalaInstance(scalaHome, appConfiguration.value.provider.scalaProvider.launcher)
+}
+
+
+libraryDependencies += "com.novocode" % "junit-interface" % "0.11" % "test"
+
+libraryDependencies += "com.typesafe.akka" %% "akka-actor" % "2.3.3" % "test"
+
+scalaVersion := "2.11.0"

sbt/src/sbt-test/tests/scala-instance-classloader/src/test/scala/Test.scala

@@ -0,0 +1,21 @@
+package akka.actor
+
+import org.junit._
+
+class BadTest {
+
+  @Test
+  def testCpIssue(): Unit = {
+    // TODO - This is merely the laziest way to run the test.  What we want to do:
+    // * Load something from our own classloader that's INSIDE the scala library
+    // * Try to load that same something from the THREAD CONTEXT classloader.
+    // * Ensure we can do both, i.e. the second used to be filtered and broken.
+    val current = Thread.currentThread.getContextClassLoader
+    val mine = this.getClass.getClassLoader
+    val system = ActorSystem()
+    def evilGetThreadExectionContextName =
+      system.asInstanceOf[ActorSystemImpl].internalCallingThreadExecutionContext.getClass.getName
+    val expected = "scala.concurrent.Future$InternalCallbackExecutor$"
+    Assert.assertEquals("Failed to grab appropriate Akka name", expected, evilGetThreadExectionContextName)
+  }
+}

sbt/src/sbt-test/tests/scala-instance-classloader/test

@@ -0,0 +1 @@
+> test

util/classpath/src/main/scala/sbt/classpath/ClassLoaders.scala

@@ -59,13 +59,8 @@ final class ClasspathFilter(parent: ClassLoader, root: ClassLoader, classpath: S
       val c = super.loadClass(className, resolve)
       if (includeLoader(c.getClassLoader, root) || fromClasspath(c))
         c
-      else {
-        System.err.println(s"DEBUGME: Failing to load class $className because it was not in expected parent chain.")
-        System.err.println(s"DEBUGME: Found: ${c.getClassLoader}")
-        System.err.println(s"DEBUGME: Expected: ${root}")
-        System.err.println(s"DEBUGME: onClasspath: ${fromClasspath(c)}")
+      else
         throw new ClassNotFoundException(className)
-      }
     }
   private[this] def fromClasspath(c: Class[_]): Boolean =
     {