[backport] -Yrelease and related ctsym/jrt tweaks

Author: som-snytt

src/compiler/scala/tools/nsc/Global.scala

@@ -129,9 +129,21 @@ class Global(var currentSettings: Settings, reporter0: 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 scala/bug#8779
-  def optimizerClassPath(base: ClassPath): ClassPath = base
+
+  /** The classpath used by inliner's bytecode repository.
+   *  If --release is used, swap the ctsym for jrt.
+   *  REPL adds a classpath entry containing products of previous runs. (scala/bug#8779)
+   *  @param base the class path to augment, nominally `this.classPath` or `platform.classPath`
+   */
+  def optimizerClassPath(base: ClassPath): ClassPath =
+    base match {
+      case AggregateClassPath(entries) if entries.head.isInstanceOf[CtSymClassPath] =>
+        JrtClassPath(release = None, unsafe = None, closeableRegistry) match {
+          case jrt :: _ => AggregateClassPath(jrt +: entries.drop(1))
+          case _ => base
+        }
+      case _ => base
+    }
 
   def classPath: ClassPath = platform.classPath
 

src/compiler/scala/tools/nsc/classpath/DirectoryClassPath.scala

@@ -13,16 +13,18 @@
 package scala.tools.nsc.classpath
 
 import java.io.{Closeable, File}
-import java.net.URL
-import java.util
+import java.net.{URI, URL}
+import java.nio.file._
 
-import scala.reflect.io.{AbstractFile, PlainFile, PlainNioFile}
-import scala.tools.nsc.util.{ClassPath, ClassRepresentation, EfficientClassPath}
-import FileUtils._
 import scala.collection.JavaConverters._
 import scala.reflect.internal.JDK9Reflectors
+import scala.reflect.io.{AbstractFile, PlainFile, PlainNioFile}
 import scala.tools.nsc.CloseableRegistry
 import scala.tools.nsc.classpath.PackageNameUtils.{packageContains, separatePkgAndClassNames}
+import scala.tools.nsc.util.{ClassPath, ClassRepresentation, EfficientClassPath}
+import scala.util.Properties.{isJavaAtLeast, javaHome}
+import scala.util.control.NonFatal
+import FileUtils._
 
 /**
  * A trait allowing to look for classpath entries in directories. It provides common logic for
@@ -71,7 +73,7 @@ trait DirectoryLookup[FileEntryType <: ClassRepresentation] extends EfficientCla
       case None => emptyFiles
       case Some(directory) => listChildren(directory, Some(isMatchingFile))
     }
-    files.map(f => createFileEntry(toAbstractFile(f)))
+    files.iterator.map(f => createFileEntry(toAbstractFile(f))).toSeq
   }
 
   override private[nsc] def list(inPackage: PackageName, onPackageEntry: PackageEntry => Unit, onClassesAndSources: ClassRepresentation => Unit): Unit = {
@@ -95,7 +97,7 @@ trait JFileDirectoryLookup[FileEntryType <: ClassRepresentation] extends Directo
   protected def emptyFiles: Array[File] = Array.empty
   protected def getSubDir(packageDirName: String): Option[File] = {
     val packageDir = new File(dir, packageDirName)
-    if (packageDir.exists && packageDir.isDirectory) Some(packageDir)
+    if (packageDir.exists && packageDir.isDirectory && packageDir.canRead) Some(packageDir)
     else None
   }
   protected def listChildren(dir: File, filter: Option[File => Boolean]): Array[File] = {
@@ -114,7 +116,7 @@ trait JFileDirectoryLookup[FileEntryType <: ClassRepresentation] extends Directo
     //
     // Note this behaviour can be enabled in javac with `javac -XDsortfiles`, but that's only
     // intended to improve determinism of the compiler for compiler hackers.
-    util.Arrays.sort(listing, (o1: File, o2: File) => o1.getName.compareTo(o2.getName))
+    java.util.Arrays.sort(listing, (o1: File, o2: File) => o1.getName.compareTo(o2.getName))
     listing
   }
   protected def getName(f: File): String = f.getName
@@ -128,44 +130,65 @@ trait JFileDirectoryLookup[FileEntryType <: ClassRepresentation] extends Directo
 }
 
 object JrtClassPath {
-  import java.nio.file._, java.net.URI
   private val jrtClassPathCache = new FileBasedCache[Unit, JrtClassPath]()
   private val ctSymClassPathCache = new FileBasedCache[String, CtSymClassPath]()
-  def apply(release: Option[String], closeableRegistry: CloseableRegistry): Option[ClassPath] = {
-    import scala.util.Properties._
-    if (!isJavaAtLeast("9")) None
+  def apply(release: Option[String], unsafe: Option[List[String]], closeableRegistry: CloseableRegistry): List[ClassPath] =
+    if (!isJavaAtLeast("9")) Nil
     else {
       // TODO escalate errors once we're sure they are fatal
       // I'm hesitant to do this immediately, because -release will still work for multi-release JARs
       // even if we're running on a JRE or a non OpenJDK JDK where ct.sym is unavailable.
       //
       // Longer term we'd like an official API for this in the JDK
-      // Discussion: http://mail.openjdk.java.net/pipermail/compiler-dev/2018-March/thread.html#11738
+      // Discussion: https://mail.openjdk.java.net/pipermail/compiler-dev/2018-March/thread.html#11738
 
       val currentMajorVersion: Int = JDK9Reflectors.runtimeVersionMajor(JDK9Reflectors.runtimeVersion()).intValue()
       release match {
-        case Some(v) if v.toInt < currentMajorVersion =>
-          try {
-            val ctSym = Paths.get(javaHome).resolve("lib").resolve("ct.sym")
-            if (Files.notExists(ctSym)) None
-            else {
-              val classPath = ctSymClassPathCache.getOrCreate(v, ctSym :: Nil, () => new CtSymClassPath(ctSym, v.toInt), closeableRegistry, true)
-              Some(classPath)
-            }
-          } catch {
-            case _: Throwable => None
+        case Some(version) if version.toInt < currentMajorVersion =>
+          val ct = createCt(version, closeableRegistry)
+          unsafe match {
+            case Some(pkgs) if pkgs.nonEmpty =>
+              createJrt(closeableRegistry) match {
+                case Nil      => ct
+                case jrt :: _ => ct :+ new FilteringJrtClassPath(jrt, pkgs: _*)
+              }
+            case _ => ct
           }
         case _ =>
-          try {
-            val fs = FileSystems.getFileSystem(URI.create("jrt:/"))
-            val classPath = jrtClassPathCache.getOrCreate((), Nil, () => new JrtClassPath(fs), closeableRegistry, false)
-            Some(classPath)
-          } catch {
-            case _: ProviderNotFoundException | _: FileSystemNotFoundException => None
-          }
+          createJrt(closeableRegistry)
       }
     }
-  }
+  private def createCt(v: String, closeableRegistry: CloseableRegistry): List[ClassPath] =
+    try {
+      val ctSym = Paths.get(javaHome).resolve("lib").resolve("ct.sym")
+      if (Files.notExists(ctSym)) Nil
+      else List(
+        ctSymClassPathCache.getOrCreate(v, ctSym :: Nil, () => new CtSymClassPath(ctSym, v.toInt), closeableRegistry, checkStamps = true)
+      )
+    } catch {
+      case NonFatal(_) => Nil
+    }
+  private def createJrt(closeableRegistry: CloseableRegistry): List[JrtClassPath] =
+    try {
+      val fs = FileSystems.getFileSystem(URI.create("jrt:/"))
+      val classPath = jrtClassPathCache.getOrCreate((), Nil, () => new JrtClassPath(fs), closeableRegistry, checkStamps = false)
+      List(classPath)
+    } catch {
+      case _: ProviderNotFoundException | _: FileSystemNotFoundException => Nil
+    }
+}
+
+final class FilteringJrtClassPath(delegate: JrtClassPath, allowed: String*) extends ClassPath with NoSourcePaths {
+  private val allowedPackages = allowed
+  private def packagePrefix(p: String, q: String) = p.startsWith(q) && (p.length == q.length || p.charAt(q.length) == '.')
+  private def ok(pkg: PackageName) = pkg.dottedString.isEmpty || allowedPackages.exists(packagePrefix(_, pkg.dottedString))
+  def asClassPathStrings: Seq[String] = delegate.asClassPathStrings
+  def asURLs: Seq[java.net.URL] = delegate.asURLs
+  private[nsc] def classes(inPackage: PackageName) = if (ok(inPackage)) delegate.classes(inPackage) else Nil
+  def findClassFile(className: String) = if (ok(PackageName(separatePkgAndClassNames(className)._1))) delegate.findClassFile(className) else None
+  private[nsc] def hasPackage(pkg: PackageName) = ok(pkg) && delegate.hasPackage(pkg)
+  private[nsc] def list(inPackage: PackageName) = if (ok(inPackage)) delegate.list(inPackage) else ClassPathEntries(Nil, Nil)
+  private[nsc] def packages(inPackage: PackageName) = if (ok(inPackage)) delegate.packages(inPackage) else Nil
 }
 
 /**
@@ -176,16 +199,15 @@ object JrtClassPath {
   *
   * The implementation assumes that no classes exist in the empty package.
   */
-final class JrtClassPath(fs: java.nio.file.FileSystem) extends ClassPath with NoSourcePaths {
-  import java.nio.file.Path, java.nio.file._
+final class JrtClassPath(fs: FileSystem) extends ClassPath with NoSourcePaths {
   type F = Path
   private val dir: Path = fs.getPath("/packages")
 
   // e.g. "java.lang" -> Seq("/modules/java.base")
   private val packageToModuleBases: Map[String, Seq[Path]] = {
-    val ps = Files.newDirectoryStream(dir).iterator().asScala
+    val ps = Files.newDirectoryStream(dir).iterator.asScala
     def lookup(pack: Path): Seq[Path] = {
-      Files.list(pack).iterator().asScala.map(l => if (Files.isSymbolicLink(l)) Files.readSymbolicLink(l) else l).toList
+      Files.list(pack).iterator.asScala.map(l => if (Files.isSymbolicLink(l)) Files.readSymbolicLink(l) else l).toList
     }
     ps.map(p => (p.toString.stripPrefix("/packages/"), lookup(p))).toMap
   }
@@ -199,7 +221,7 @@ final class JrtClassPath(fs: java.nio.file.FileSystem) extends ClassPath with No
     if (inPackage.isRoot) Nil
     else {
       packageToModuleBases.getOrElse(inPackage.dottedString, Nil).flatMap(x =>
-        Files.list(x.resolve(inPackage.dirPathTrailingSlash)).iterator().asScala.filter(_.getFileName.toString.endsWith(".class"))).map(x =>
+        Files.list(x.resolve(inPackage.dirPathTrailingSlash)).iterator.asScala.filter(_.getFileName.toString.endsWith(".class"))).map(x =>
         ClassFileEntryImpl(new PlainNioFile(x))).toVector
     }
   }
@@ -208,7 +230,7 @@ final class JrtClassPath(fs: java.nio.file.FileSystem) extends ClassPath with No
     if (inPackage.isRoot) ClassPathEntries(packages(inPackage), Nil)
     else ClassPathEntries(packages(inPackage), classes(inPackage))
 
-  def asURLs: Seq[URL] = Seq(new URL("jrt:/"))
+  def asURLs: Seq[URL] = Seq(new URI("jrt:/").toURL)
   // We don't yet have a scheme to represent the JDK modules in our `-classpath`.
   // java models them as entries in the new "module path", we'll probably need to follow this.
   def asClassPathStrings: Seq[String] = Nil
@@ -226,26 +248,26 @@ final class JrtClassPath(fs: java.nio.file.FileSystem) extends ClassPath with No
 }
 
 /**
-  * Implementation `ClassPath` based on the \$JAVA_HOME/lib/ct.sym backing http://openjdk.java.net/jeps/247
+  * Implementation `ClassPath` based on the \$JAVA_HOME/lib/ct.sym backing https://openjdk.java.net/jeps/247
   */
 final class CtSymClassPath(ctSym: java.nio.file.Path, release: Int) extends ClassPath with NoSourcePaths with Closeable {
   import java.nio.file.Path, java.nio.file._
 
   private val fileSystem: FileSystem = FileSystems.newFileSystem(ctSym, null: ClassLoader)
-  private val root: Path = fileSystem.getRootDirectories.iterator().next
-  private val roots = Files.newDirectoryStream(root).iterator().asScala.toList
+  private val root: Path = fileSystem.getRootDirectories.iterator.next
+  private val roots = Files.newDirectoryStream(root).iterator.asScala.toList
 
-  // http://mail.openjdk.java.net/pipermail/compiler-dev/2018-March/011737.html
+  // https://mail.openjdk.java.net/pipermail/compiler-dev/2018-March/011737.html
   private def codeFor(major: Int): String = if (major < 10) major.toString else ('A' + (major - 10)).toChar.toString
 
   private val releaseCode: String = codeFor(release)
   private def fileNameMatchesRelease(fileName: String) = !fileName.contains("-") && fileName.contains(releaseCode) // exclude `9-modules`
   private val rootsForRelease: List[Path] = roots.filter(root => fileNameMatchesRelease(root.getFileName.toString))
 
   // e.g. "java.lang" -> Seq(/876/java/lang, /87/java/lang, /8/java/lang))
-  private val packageIndex: scala.collection.Map[String, Seq[Path]] = {
+  private val packageIndex: scala.collection.Map[String, scala.collection.Seq[Path]] = {
     val index = collection.mutable.AnyRefMap[String, collection.mutable.ListBuffer[Path]]()
-    val isJava12OrHigher = scala.util.Properties.isJavaAtLeast("12")
+    val isJava12OrHigher = isJavaAtLeast("12")
     rootsForRelease.foreach(root => Files.walk(root).iterator().asScala.filter(Files.isDirectory(_)).foreach { p =>
       val moduleNamePathElementCount = if (isJava12OrHigher) 1 else 0
       if (p.getNameCount > root.getNameCount + moduleNamePathElementCount) {
@@ -265,7 +287,7 @@ final class CtSymClassPath(ctSym: java.nio.file.Path, release: Int) extends Clas
     if (inPackage.isRoot) Nil
     else {
       val sigFiles = packageIndex.getOrElse(inPackage.dottedString, Nil).iterator.flatMap(p =>
-        Files.list(p).iterator().asScala.filter(_.getFileName.toString.endsWith(".sig")))
+        Files.list(p).iterator.asScala.filter(_.getFileName.toString.endsWith(".sig")))
       sigFiles.map(f => ClassFileEntryImpl(new PlainNioFile(f))).toVector
     }
   }

src/compiler/scala/tools/nsc/settings/ScalaSettings.scala

@@ -244,6 +244,7 @@ trait ScalaSettings extends StandardScalaSettings with Warnings { _: MutableSett
   val Yvirtpatmat     = BooleanSetting    ("-Yvirtpatmat", "Enable pattern matcher virtualization")
   val Youtline        = BooleanSetting    ("-Youtline", "Don't compile method bodies. Use together with `-Ystop-afer:pickler to generate the pickled signatures for all source files.").internalOnly()
 
+  val unsafe = MultiStringSetting("-Yrelease", "packages", "Expose platform packages hidden under --release")
   val exposeEmptyPackage = BooleanSetting ("-Yexpose-empty-package", "Internal only: expose the empty package.").internalOnly()
   val Ydelambdafy        = ChoiceSetting  ("-Ydelambdafy", "strategy", "Strategy used for translating lambdas into JVM code.", List("inline", "method", "method-ref"), "method")
   val YmacroClasspath = PathSetting       ("-Ymacro-classpath", "The classpath used to reflectively load macro implementations, default is the compilation classpath.", "")

src/compiler/scala/tools/nsc/settings/StandardScalaSettings.scala

@@ -63,6 +63,8 @@ trait StandardScalaSettings { _: MutableSettings =>
       if (!isJavaAtLeast("9") && current > 8) errorFn.apply("-release is only supported on JVM 9 and higher")
       if (target.valueSetByUser.map(_.toInt > current).getOrElse(false)) errorFn("-release cannot be less than -target")
     }
+    .withAbbreviation("--release")
+    .withAbbreviation("-java-output-version")
   def releaseValue: Option[String] = release.valueSetByUser
   val target =
     ChoiceSetting("-target", "target", "Target platform for object files. All JVM 1.5 - 1.7 targets are deprecated.", AllTargetVersions, DefaultTargetVersion)

src/compiler/scala/tools/util/PathResolver.scala

@@ -260,7 +260,9 @@ final class PathResolver(settings: Settings, closeableRegistry: CloseableRegistr
 
     // Assemble the elements!
     def basis = List[Traversable[ClassPath]](
-      jrt,                                          // 0. The Java 9+ classpath (backed by the ct.sym or jrt:/ virtual system, if available)
+      if (settings.javabootclasspath.isSetByUser)   // respect explicit `-javabootclasspath rt.jar`
+        Nil
+      else jrt,                                     // 0. The Java 9+ classpath (backed by the ct.sym or jrt:/ virtual system, if available)
       classesInPath(javaBootClassPath),             // 1. The Java bootstrap class path.
       contentsOfDirsInPath(javaExtDirs),            // 2. The Java extension class path.
       classesInExpandedPath(javaUserClassPath),     // 3. The Java application class path.
@@ -271,7 +273,7 @@ final class PathResolver(settings: Settings, closeableRegistry: CloseableRegistr
       sourcesInPath(sourcePath)                     // 7. The Scala source path.
     )
 
-    private def jrt: Option[ClassPath] = JrtClassPath.apply(settings.releaseValue, closeableRegistry)
+    private def jrt: List[ClassPath] = JrtClassPath.apply(settings.releaseValue, settings.unsafe.valueSetByUser, closeableRegistry)
 
     lazy val containers = basis.flatten.distinct
 

src/repl/scala/tools/nsc/interpreter/ReplGlobal.scala

@@ -89,12 +89,15 @@ trait ReplGlobal extends Global {
   }
 
   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, closeableRegistry)
-        AggregateClassPath.createAggregate(platform.classPath, replOutClasspath)
+    def withBase(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, closeableRegistry)
+          AggregateClassPath.createAggregate(base, replOutClasspath)
+      }
     }
+    withBase(super.optimizerClassPath(base))
   }
 }

test/files/neg/unsafe.check

@@ -0,0 +1,4 @@
+unsafe.scala:9: error: value threadId is not a member of Thread
+  def f(t: Thread) = t.threadId
+                       ^
+one error found

test/files/neg/unsafe.scala

@@ -0,0 +1,10 @@
+
+// scalac: --release:8 -Yrelease:java.lang
+// javaVersion: 19+
+
+// -Yrelease opens packages but does not override class definitions
+// because ct.sym comes first
+
+class C {
+  def f(t: Thread) = t.threadId
+}

test/files/pos/unsafe.scala

@@ -0,0 +1,21 @@
+
+// scalac: --release:8 -Yrelease:sun.misc
+
+import sun.misc.Unsafe
+
+class C {
+  val f = classOf[Unsafe].getDeclaredField("theUnsafe")
+  f.setAccessible(true)
+  val unsafe = f.get(null).asInstanceOf[Unsafe]
+
+  val k = unsafe.allocateInstance(classOf[K]).asInstanceOf[K]
+  assert(k.value == 0)
+}
+
+class K {
+  val value = 42
+}
+
+object Test extends App {
+  new C
+}

test/junit/scala/tools/nsc/classpath/JrtClassPathTest.scala

@@ -27,7 +27,7 @@ class JrtClassPathTest {
         val elements = new ClassPathFactory(settings, closeableRegistry).classesInPath(resolver.Calculated.javaBootClassPath)
         AggregateClassPath(elements)
       }
-      else JrtClassPath(None, closeableRegistry).get
+      else JrtClassPath(release = None, unsafe = None, closeableRegistry).head
 
     assertEquals(Nil, cp.classes(""))
     assertTrue(cp.packages("java").toString, cp.packages("java").exists(_.name == "java.lang"))