3 files changed, 23 insertions, 10 deletions
diff --git a/src/library/scala/annotation/migration.scala b/src/library/scala/annotation/migration.scala
index 49fea9434c..adb6de6afd 100644
--- a/src/library/scala/annotation/migration.scala
+++ b/src/library/scala/annotation/migration.scala
@@ -17,7 +17,8 @@ package scala.annotation
  * order between Scala 2.7 and 2.8.
  *
  * @param message A message describing the change, which is emitted
- * by the compiler if the flag `-Xmigration` is set.
+ * by the compiler if the flag `-Xmigration` indicates a version 
+ * prior to the changedIn version.
  *
  * @param changedIn The version, in which the behaviour change was
  * introduced.
diff --git a/src/library/scala/collection/immutable/Stream.scala b/src/library/scala/collection/immutable/Stream.scala
index 1c461973e4..5bb4ef5f21 100644
--- a/src/library/scala/collection/immutable/Stream.scala
+++ b/src/library/scala/collection/immutable/Stream.scala
@@ -841,9 +841,16 @@ self =>
    * // produces: "1, 2, 3, 4, 5, 6"
    * }}}
    */
-  override def distinct: Stream[A] =
-    if (isEmpty) this
-    else cons(head, tail.filter(head != _).distinct)
+  override def distinct: Stream[A] = {
+    // This should use max memory proportional to N, whereas
+    // recursively calling distinct on the tail is N^2.
+    def loop(seen: Set[A], rest: Stream[A]): Stream[A] = {
+      if (rest.isEmpty) rest
+      else if (seen(rest.head)) loop(seen, rest.tail)
+      else cons(rest.head, loop(seen + rest.head, rest.tail))
+    }
+    loop(Set(), this)
+  }
 
   /** Returns a new sequence of given length containing the elements of this
    * sequence followed by zero or more occurrences of given elements.
diff --git a/src/library/scala/collection/mutable/ListMap.scala b/src/library/scala/collection/mutable/ListMap.scala
index 212ee917c5..7f05deffc8 100644
--- a/src/library/scala/collection/mutable/ListMap.scala
+++ b/src/library/scala/collection/mutable/ListMap.scala
@@ -12,6 +12,7 @@ package scala.collection
 package mutable
 
 import generic._
+import annotation.tailrec
 
 /** A simple mutable map backed by a list.
  *
@@ -47,13 +48,17 @@ extends AbstractMap[A, B]
 
   def get(key: A): Option[B] = elems find (_._1 == key) map (_._2)
   def iterator: Iterator[(A, B)] = elems.iterator
-  def += (kv: (A, B)) = { elems = remove(kv._1, elems); elems = kv :: elems; siz += 1; this }
-  def -= (key: A) = { elems = remove(key, elems); this }
 
-  private def remove(key: A, elems: List[(A, B)]): List[(A, B)] =
-    if (elems.isEmpty) elems
-    else if (elems.head._1 == key) { siz -= 1; elems.tail }
-    else elems.head :: remove(key, elems.tail)
+  def += (kv: (A, B)) = { elems = remove(kv._1, elems, List()); elems = kv :: elems; siz += 1; this }
+  def -= (key: A) = { elems = remove(key, elems, List()); this }
+
+  @tailrec
+  private def remove(key: A, elems: List[(A, B)], acc: List[(A, B)]): List[(A, B)] = {
+    if (elems.isEmpty) acc
+    else if (elems.head._1 == key) { siz -= 1; acc ::: elems.tail }
+    else remove(key, elems.tail, elems.head :: acc)
+  }
+
 
   override def clear() = { elems = List(); siz = 0 }
   override def size: Int = siz