Merge pull request #473 from ravwojdyla/fix_classnotfound

Fix sbt/sbt#3736. Recurse into classloader of the class not the root

CONTRIBUTING.md

@@ -14,7 +14,7 @@ compilation works in 1.0.
 Guides:
 
 * [Understanding Incremental Recompilation](http://www.scala-sbt.org/0.13/docs/Understanding-Recompilation.html).
-* [Scala Lang blog post on Zinc release](https://www.scala-lang.org/blog/2017/01/03/zinc-blog-post.html).
+* [Scala Lang blog post on Zinc release](https://www.scala-lang.org/blog/2017/11/03/zinc-blog-1.0.html).
 * All the issues and PRs labelled as `docs` will help you understand different
   aspects of Zinc. They both count with concrete information that are helpful
   to understand tradeoffs and implementation details.

internal/zinc-classpath/src/main/scala/sbt/internal/inc/classpath/ClassLoaders.scala

@@ -99,9 +99,9 @@ final class ClasspathFilter(parent: ClassLoader, root: ClassLoader, classpath: S
   }
 
   @tailrec private[this] def includeLoader(c: ClassLoader, base: ClassLoader): Boolean =
-    (base ne null) && (
-      (c eq base) || includeLoader(c, base.getParent)
-    )
+    (base ne null) &&
+      (c ne null) &&
+      ((c eq base) || includeLoader(c.getParent, base))
 }
 
 /**

internal/zinc-scripted/src/test/scala/sbt/internal/inc/IncHandler.scala

@@ -164,7 +164,7 @@ final class IncHandler(directory: File, cacheDir: File, scriptedLog: ManagedLogg
         val analysis = p.compile(i)
         p.discoverMainClasses(Some(analysis.apis)) match {
           case Seq(mainClassName) =>
-            val classpath = i.si.allJars :+ p.classesDir
+            val classpath: Array[File] = (i.si.allJars :+ p.classesDir) map { _.getAbsoluteFile }
             val loader = ClasspathUtilities.makeLoader(classpath, i.si, directory)
             val main = p.getMainMethod(mainClassName, loader)
             p.invokeMain(loader, main, params)

zinc/src/sbt-test/general/classpath-filter/A.scala

@@ -0,0 +1,10 @@
+// https://github.com/sbt/sbt/issues/3736
+// https://github.com/raboof/sbt-run-classloading/blob/master/src/main/scala/Main.scala
+object Main extends App {
+  Class.forName("scala.Int")
+
+  val classLoader = Option(Thread.currentThread.getContextClassLoader).get
+  Class.forName("scala.Int", true, classLoader)
+
+  Class.forName("scala.Int", false, classLoader)
+}

zinc/src/sbt-test/general/classpath-filter/test

@@ -0,0 +1 @@
+> run