The birth of the @switch and @tailrec annotations.

They are located in package scala.annotation. Also in this patch:

 * numerous test cases for both annotations
 * addition of @tailrec and @switch in a few strategic locations
 * fixes for critical section NewScanners methods which were not being
   compiled into switches, immediately proving the value of @switch
 * tail recursive implementations for Iterator.{ dropWhile, drop}
   and List.dropWhile tagged with @tailrec, closing bug #1376

1 files changed, 53 insertions, 0 deletions

diff --git a/test/files/neg/tailrec.scala b/test/files/neg/tailrec.scala
new file mode 100644
index 0000000000..4c45672f93
--- /dev/null
+++ b/test/files/neg/tailrec.scala
@@ -0,0 +1,53 @@
+import scala.annotation.tailrec
+
+// putting @tailrec through the paces
+object Main {
+  @tailrec
+  def facfail(n: Int): Int =
+    if (n == 0) 1
+    else n * facfail(n - 1)
+
+  @tailrec
+  def facsucc(n: Int, acc: Int): Int =
+    if (n == 0) acc
+    else facsucc(n - 1, n * acc)
+
+  @tailrec def loopy1(x: Int): Int = loopy1(x - 1)
+
+  def ding {
+    object dong {
+      @tailrec def loopy2(x: Int): Int = loopy2(x)
+    }
+    ()
+  }
+
+  def inner(q: Int) = {
+    @tailrec
+    def loopy3(x: Int): Int = loopy3(x + 1)
+
+    loopy3(q)
+  }
+}
+
+class Bob {
+  // these should work
+  @tailrec private def succ1(x: Int): Int = succ1(x)
+  @tailrec final def succ2(x: Int): Int = succ2(x)
+  @tailrec final def succ3[T](in: List[T], acc: List[T]): List[T] = in match {
+    case Nil      => Nil
+    case x :: xs  => succ3(xs, x :: acc)
+  }
+
+  // not private, not final
+  @tailrec def fail1(x: Int): Int = fail1(x)
+
+  // a typical between-chair-and-keyboard error
+  @tailrec def fail2[T](xs: List[T]): List[T] = xs match {
+    case Nil      => Nil
+    case x :: xs  => x :: fail2(xs)
+  }
+
+  object innerBob {
+    @tailrec def succ4(x: Int): Int = succ4(x)
+  }
+}