Merged revisions 22897 via svnmerge from

https://lampsvn.epfl.ch/svn-repos/scala/scala/trunk

........
  r22897 | dragos | 2010-09-01 18:01:59 +0200 (Wed, 01 Sep 2010) | 1 line

  Closes #1220. Stream.tail is now thread safe. Review by odersky.
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2 files changed, 39 insertions, 0 deletions

diff --git a/test/files/run/concurrent-stream.check b/test/files/run/concurrent-stream.check
new file mode 100644
index 0000000000..d4adf84490
--- /dev/null
+++ b/test/files/run/concurrent-stream.check
@@ -0,0 +1,3 @@
+Testing standard cons.
+Evaluation 0: List(0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
+Evaluation 1: List(0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
diff --git a/test/files/run/concurrent-stream.scala b/test/files/run/concurrent-stream.scala
new file mode 100644
index 0000000000..42c695964e
--- /dev/null
+++ b/test/files/run/concurrent-stream.scala
@@ -0,0 +1,36 @@
+// test concurrent calls to Stream.tail
+object Test  {
+
+def slowRange(from: Int, until: Int, cons: (Int, => Stream[Int]) => Stream[Int]): Stream[Int] = {
+  var current = from
+  def next: Stream[Int] = {
+    Thread.sleep(100)
+    if (current >= until) Stream.empty
+    else {
+      val stream = cons(current, next)
+      current += 1
+      stream
+    }
+  }
+  next
+}
+
+def testCons(cons: (Int, => Stream[Int]) => Stream[Int]): Unit = {
+  import scala.actors.Actor._
+
+  val stream = slowRange(0, 10, cons)
+  val main = self
+  actor { main ! stream.toList }
+  actor { main ! stream.toList }
+  val eval0 = receive { case list: List[Int] => list }
+  val eval1 = receive { case list: List[Int] => list }
+  println("Evaluation 0: " + eval0)
+  println("Evaluation 1: " + eval1)
+}
+
+  def main(args: Array[String]) {
+    println("Testing standard cons.")
+    testCons(Stream.cons.apply(_, _))
+  }
+}
+