Fix and test for #2446.

1 files changed, 11 insertions, 15 deletions

diff --git a/src/library/scala/collection/VectorLike.scala b/src/library/scala/collection/VectorLike.scala
index d4b2ca1d4c..c0331d9758 100644
--- a/src/library/scala/collection/VectorLike.scala
+++ b/src/library/scala/collection/VectorLike.scala
@@ -13,6 +13,7 @@ package scala.collection
 
 import generic._
 import mutable.ArrayBuffer
+import scala.annotation.tailrec
 
 /** Sequences that support O(1) element access and O(1) length computation.
  *  This class does not add any methods to Seq but overrides several
@@ -77,27 +78,22 @@ trait VectorLike[+A, +Repr] extends SeqLike[A, Repr] { self =>
     if (i < length) Some(this(i)) else None
   }
 
-  private def foldl[B](start: Int, z: B, op: (B, A) => B): B = {
-    var i = start
-    val len = length
-    var result = z
-    while (i < len) {
-      result = op(result, this(i))
-      i += 1
-    }
-    result
-  }
+  @tailrec
+  private def foldl[B](start: Int, end: Int, z: B, op: (B, A) => B): B =
+    if (start == end) z
+    else foldl(start + 1, end, op(z, this(start)), op)
 
-  private def foldr[B](start: Int, len: Int, z: B, op: (A, B) => B): B =
-    if (start == len) z
-    else op(this(start), foldr(start + 1, len, z, op))
+  @tailrec
+  private def foldr[B](start: Int, end: Int, z: B, op: (A, B) => B): B =
+    if (start == end) z
+    else foldr(start, end - 1, op(this(end - 1), z), op)
 
   override def foldLeft[B](z: B)(op: (B, A) => B): B =
-    foldl(0, z, op)
+    foldl(0, length, z, op)
   override def foldRight[B](z: B)(op: (A, B) => B): B =
     foldr(0, length, z, op)
   override def reduceLeft[B >: A](op: (B, A) => B): B =
-    if (length > 0) foldl(1, this(0), op) else super.reduceLeft(op)
+    if (length > 0) foldl(1, length, this(0), op) else super.reduceLeft(op)
   override def reduceRight[B >: A](op: (A, B) => B): B =
     if (length > 0) foldr(0, length - 1, this(length - 1), op) else super.reduceRight(op)