Added -Xmigration option and @migration annotat...

Added -Xmigration option and @migration annotation. At present it will
warn about the following changes from 2.7 to 2.8:

  Stack iterator order reversed
  mutable.Set.map returns a Set and thus discards duplicates
  A case 'x @ Pattern' matches differently than 'Pattern'

Review by odersky.

1 files changed, 13 insertions, 2 deletions

diff --git a/src/library/scala/collection/mutable/Stack.scala b/src/library/scala/collection/mutable/Stack.scala
index bbb4189dc3..8f626e7f33 100644
--- a/src/library/scala/collection/mutable/Stack.scala
+++ b/src/library/scala/collection/mutable/Stack.scala
@@ -15,6 +15,7 @@ package mutable
 import generic._
 import collection.immutable.{List, Nil}
 import collection.Iterator
+import annotation.migration
 
 /** A stack implements a data structure which allows to store and retrieve
  *  objects in a last-in-first-out (LIFO) fashion.
@@ -74,8 +75,13 @@ class Stack[A] private (var elems: List[A]) extends scala.collection.Seq[A] with
    */
   def pushAll(elems: scala.collection.Traversable[A]): this.type = { for (elem <- elems) { push(elem); () }; this }
 
-  @deprecated("use pushAll") def ++=(it: Iterator[A]): this.type = pushAll(it)
-  @deprecated("use pushAll") def ++=(it: scala.collection.Iterable[A]): this.type = pushAll(it)
+  @deprecated("use pushAll")
+  @migration(2, 8, "Stack ++= now pushes arguments on the stack from left to right.")
+  def ++=(it: Iterator[A]): this.type = pushAll(it)
+
+  @deprecated("use pushAll")
+  @migration(2, 8, "Stack ++= now pushes arguments on the stack from left to right.")
+  def ++=(it: scala.collection.Iterable[A]): this.type = pushAll(it)
 
   /** Returns the top element of the stack. This method will not remove
    *  the element from the stack. An error is signaled if there is no
@@ -112,14 +118,19 @@ class Stack[A] private (var elems: List[A]) extends scala.collection.Seq[A] with
    *
    *  @return an iterator over all stack elements.
    */
+  @migration(2, 8, "Stack iterator and foreach now traverse in FIFO order.")
   override def iterator: Iterator[A] = elems.iterator
 
   /** Creates a list of all stack elements in LIFO order.
    *
    *  @return the created list.
    */
+  @migration(2, 8, "Stack iterator and foreach now traverse in FIFO order.")
   override def toList: List[A] = elems
 
+  @migration(2, 8, "Stack iterator and foreach now traverse in FIFO order.")
+  override def foreach[U](f: A => U): Unit = super.foreach(f)
+
   /** This method clones the stack.
    *
    *  @return  a stack with the same elements.