From eb2d8e39853f776af2c9e2c2d1b479d67641496b Mon Sep 17 00:00:00 2001
From: Aleksandar Pokopec <aleksandar.prokopec@epfl.ch>
Date: Wed, 17 Nov 2010 17:04:12 +0000
Subject: Fixes #3989.

No review.
---
 .../scala/collection/immutable/ListMap.scala       | 24 ++++++++--------------
 test/files/run/t3989.scala                         |  1 +
 test/files/run/t3996.scala                         |  1 +
 3 files changed, 10 insertions(+), 16 deletions(-)

diff --git a/src/library/scala/collection/immutable/ListMap.scala b/src/library/scala/collection/immutable/ListMap.scala
index 4b7e512e47..61cee12c13 100644
--- a/src/library/scala/collection/immutable/ListMap.scala
+++ b/src/library/scala/collection/immutable/ListMap.scala
@@ -183,22 +183,14 @@ class ListMap[A, +B] extends Map[A, B] with MapLike[A, B, ListMap[A, B]] {
      *  @param k ...
      *  @return  ...
      */
-    override def - (k: A): ListMap[A, B1] = remove0(this, k, ListMap[A, B1]())
-
-    // this solution was nicer and possibly more efficient, but resulted in stack overflows:
-    // if (k == key)
-    //   next
-    // else {
-    //   val tail = next - k
-    //   if (tail eq next) this
-    //   else new tail.Node(key, value)
-    // }
-
-    @tailrec private def remove0(cur: ListMap[A, B1], k: A, acc: ListMap[A, B1]): ListMap[A, B1] =
-      if (cur.nonEmpty) {
-        if (k == cur.key) remove0(cur.next, k, acc)
-        else remove0(cur.next, k, new acc.Node(cur.key, cur.value))
-      } else cur
+    override def - (k: A): ListMap[A, B1] =
+      if (k == key)
+        next
+      else {
+        val tail = next - k
+        if (tail eq next) this
+        else new tail.Node(key, value)
+      }
 
     override protected def next: ListMap[A, B1] = ListMap.this
   }
diff --git a/test/files/run/t3989.scala b/test/files/run/t3989.scala
index d519978e54..0daa8abee3 100644
--- a/test/files/run/t3989.scala
+++ b/test/files/run/t3989.scala
@@ -5,6 +5,7 @@
 
 class Foo{ override def equals(o: Any) = false; override def hashCode = 1}
 
+// should not result in a stack overflow
 object Test {
   def main(args: Array[String]) {
     import collection.immutable.HashMap
diff --git a/test/files/run/t3996.scala b/test/files/run/t3996.scala
index 1bb1216390..e6e5549cfa 100644
--- a/test/files/run/t3996.scala
+++ b/test/files/run/t3996.scala
@@ -3,6 +3,7 @@
 
 
 
+// should not result in a stack overflow
 object Test {
   def main(args: Array[String]) {
     import collection.mutable.LinkedList
-- 
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