SI-8779 Enable inlining of code within a REPL session

The REPL has a long running instance of Global which outputs
classfiles by default to a VirtualDirectory. The inliner did not find
any of these class files when compiling calls to methods defined in
previous runs (ie, previous lines of input.)

This commit:

  - Adds a hook to augment the classpath that the optimizer searches,
    and uses this in the REPL to add the output directory
  - Fixes the implementation of `findClassFile` in VirtualDirectory,
    which doesn't seem to have been used in anger before. I've factored out
    some common code into a new method on `AbstractFile`.
  - Fixes a similar problem getSubDir reported by Li Haoyi
  - Adds missing unit test coverage.

This also fixes a bug in REPL autocompletion for types defined
in packages >= 2 level deep (with the `:paste -raw` command).
I've added a test for this case.

5 files changed, 38 insertions, 20 deletions

diff --git a/src/compiler/scala/tools/nsc/Global.scala b/src/compiler/scala/tools/nsc/Global.scala
index a7880c72d7..e58d2d3b43 100644
--- a/src/compiler/scala/tools/nsc/Global.scala
+++ b/src/compiler/scala/tools/nsc/Global.scala
@@ -95,6 +95,9 @@ class Global(var currentSettings: Settings, var reporter: Reporter)
 
   type ThisPlatform = JavaPlatform { val global: Global.this.type }
   lazy val platform: ThisPlatform  = new GlobalPlatform
+  /* A hook for the REPL to add a classpath entry containing products of previous runs to inliner's bytecode repository*/
+  // Fixes SI-8779
+  def optimizerClassPath(base: ClassPath): ClassPath = base
 
   def classPath: ClassPath = platform.classPath
 
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/BTypesFromSymbols.scala b/src/compiler/scala/tools/nsc/backend/jvm/BTypesFromSymbols.scala
index edb75514e8..f7ee36c1ba 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/BTypesFromSymbols.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/BTypesFromSymbols.scala
@@ -37,7 +37,7 @@ class BTypesFromSymbols[G <: Global](val global: G) extends BTypes {
   val coreBTypes = new CoreBTypesProxy[this.type](this)
   import coreBTypes._
 
-  val byteCodeRepository: ByteCodeRepository[this.type] = new ByteCodeRepository(global.classPath, this)
+  val byteCodeRepository: ByteCodeRepository[this.type] = new ByteCodeRepository(global.optimizerClassPath(global.classPath), this)
 
   val localOpt: LocalOpt[this.type] = new LocalOpt(this)
 
diff --git a/src/compiler/scala/tools/nsc/classpath/VirtualDirectoryClassPath.scala b/src/compiler/scala/tools/nsc/classpath/VirtualDirectoryClassPath.scala
index 8df0c3743d..6fefaf0da0 100644
--- a/src/compiler/scala/tools/nsc/classpath/VirtualDirectoryClassPath.scala
+++ b/src/compiler/scala/tools/nsc/classpath/VirtualDirectoryClassPath.scala
@@ -1,9 +1,11 @@
 package scala.tools.nsc.classpath
 
 import scala.tools.nsc.util.ClassRepresentation
-import scala.reflect.io.{Path, PlainFile, VirtualDirectory, AbstractFile}
+import scala.reflect.io.{AbstractFile, Path, PlainFile, VirtualDirectory}
 import FileUtils._
 import java.net.URL
+
+import scala.reflect.internal.util.AbstractFileClassLoader
 import scala.tools.nsc.util.ClassPath
 
 case class VirtualDirectoryClassPath(dir: VirtualDirectory) extends ClassPath with DirectoryLookup[ClassFileEntryImpl] with NoSourcePaths {
@@ -11,7 +13,7 @@ case class VirtualDirectoryClassPath(dir: VirtualDirectory) extends ClassPath wi
 
   protected def emptyFiles: Array[AbstractFile] = Array.empty
   protected def getSubDir(packageDirName: String): Option[AbstractFile] =
-    Option(dir.lookupName(packageDirName, directory = true))
+    Option(AbstractFileClassLoader.lookupPath(dir)(packageDirName.split('/'), directory = true))
   protected def listChildren(dir: AbstractFile, filter: Option[AbstractFile => Boolean] = None): Array[F] = filter match {
     case Some(f) => dir.iterator.filter(f).toArray
     case _ => dir.toArray
@@ -27,10 +29,8 @@ case class VirtualDirectoryClassPath(dir: VirtualDirectory) extends ClassPath wi
   override def findClass(className: String): Option[ClassRepresentation] = findClassFile(className) map ClassFileEntryImpl
 
   def findClassFile(className: String): Option[AbstractFile] = {
-    val relativePath = FileUtils.dirPath(className)
-    val classFile = new PlainFile(Path(s"$dir/$relativePath.class"))
-    if (classFile.exists) Some(classFile)
-    else None
+    val relativePath = FileUtils.dirPath(className) + ".class"
+    Option(AbstractFileClassLoader.lookupPath(dir)(relativePath split '/', directory = false))
   }
 
   private[nsc] def classes(inPackage: String): Seq[ClassFileEntry] = files(inPackage)
diff --git a/src/reflect/scala/reflect/internal/util/AbstractFileClassLoader.scala b/src/reflect/scala/reflect/internal/util/AbstractFileClassLoader.scala
index b5030460b8..3cede1b3c5 100644
--- a/src/reflect/scala/reflect/internal/util/AbstractFileClassLoader.scala
+++ b/src/reflect/scala/reflect/internal/util/AbstractFileClassLoader.scala
@@ -12,6 +12,20 @@ import java.security.cert.Certificate
 import java.security.{ ProtectionDomain, CodeSource }
 import java.util.{ Collections => JCollections, Enumeration => JEnumeration }
 
+object AbstractFileClassLoader {
+  // should be a method on AbstractFile, but adding in `internal.util._` for now as we're in a minor release
+  private[scala] final def lookupPath(base: AbstractFile)(pathParts: Seq[String], directory: Boolean): AbstractFile = {
+    var file: AbstractFile = base
+    for (dirPart <- pathParts.init) {
+      file = file.lookupName(dirPart, directory = true)
+      if (file == null)
+        return null
+    }
+
+    file.lookupName(pathParts.last, directory = directory)
+  }
+}
+
 /** A class loader that loads files from a [[scala.reflect.io.AbstractFile]].
  *
  *  @author Lex Spoon
@@ -25,19 +39,7 @@ class AbstractFileClassLoader(val root: AbstractFile, parent: ClassLoader)
     else s"${name.replace('.', '/')}.class"
 
   protected def findAbstractFile(name: String): AbstractFile = {
-    var file: AbstractFile = root
-    val pathParts          = name split '/'
-
-    for (dirPart <- pathParts.init) {
-      file = file.lookupName(dirPart, directory = true)
-      if (file == null)
-        return null
-    }
-
-    file.lookupName(pathParts.last, directory = false) match {
-      case null   => null
-      case file   => file
-    }
+    AbstractFileClassLoader.lookupPath(root)(name split '/', directory = false)
   }
 
   protected def dirNameToPath(name: String): String =
diff --git a/src/repl/scala/tools/nsc/interpreter/ReplGlobal.scala b/src/repl/scala/tools/nsc/interpreter/ReplGlobal.scala
index cf055e0758..0bb9eb6a0b 100644
--- a/src/repl/scala/tools/nsc/interpreter/ReplGlobal.scala
+++ b/src/repl/scala/tools/nsc/interpreter/ReplGlobal.scala
@@ -6,6 +6,9 @@
 package scala.tools.nsc
 package interpreter
 
+import scala.tools.nsc.backend.JavaPlatform
+import scala.tools.nsc.classpath.{AggregateClassPath, ClassPathFactory}
+import scala.tools.nsc.util.ClassPath
 import typechecker.Analyzer
 
 /** A layer on top of Global so I can guarantee some extra
@@ -31,4 +34,14 @@ trait ReplGlobal extends Global {
       new util.AbstractFileClassLoader(virtualDirectory, loader) {}
     }
   }
+
+  override def optimizerClassPath(base: ClassPath): ClassPath = {
+    settings.outputDirs.getSingleOutput match {
+      case None => base
+      case Some(out) =>
+        // Make bytecode of previous lines available to the inliner
+        val replOutClasspath = ClassPathFactory.newClassPath(settings.outputDirs.getSingleOutput.get, settings)
+        AggregateClassPath.createAggregate(platform.classPath, replOutClasspath)
+    }
+  }
 }