SI-6415, overly eager evaluation in Stream.

The lengthCompare method in LinearSeqOptimized was looking one
step further than it needed to in order to give the correct
result, which was creating some unwanted side effects related to
Streams.

2 files changed, 34 insertions, 0 deletions

diff --git a/test/files/run/streams.check b/test/files/run/streams.check
index 7f894052d9..db6d2eebab 100644
--- a/test/files/run/streams.check
+++ b/test/files/run/streams.check
@@ -1,5 +1,8 @@
 Stream()
 Stream()
+true
+true
+true
 
 Array(1)
 Stream(1, ?)
@@ -8,12 +11,21 @@ Stream()
 Stream()
 Stream(1)
 Stream()
+true
+true
+true
+true
 
 Array(1, 2)
 Stream(2)
 Stream()
 Stream(1, 2)
 Stream()
+true
+true
+true
+true
+true
 
 999
 512
@@ -23,3 +35,5 @@ Stream(100001, ?)
 true
 true
 705082704
+
+true
diff --git a/test/files/run/streams.scala b/test/files/run/streams.scala
index 51b4e5d76c..03b2622edd 100644
--- a/test/files/run/streams.scala
+++ b/test/files/run/streams.scala
@@ -2,6 +2,9 @@ object Test extends App {
   val s0: Stream[Int] = Stream.empty
   println(s0.take(1))
   println(s0.takeWhile(_ > 0))
+  println(s0.lengthCompare(-5) > 0)
+  println(s0.lengthCompare(0) == 0)
+  println(s0.lengthCompare(5) < 0)
   println
 
   val s1 = Stream.cons(1, Stream.empty)
@@ -12,6 +15,10 @@ object Test extends App {
   println(s1.drop(2))
   println(s1.drop(-1))
   println(s1.dropWhile(_ > 0))
+  println(s1.lengthCompare(-5) > 0)
+  println(s1.lengthCompare(0) > 0)
+  println(s1.lengthCompare(1) == 0)
+  println(s1.lengthCompare(5) < 0)
   println
 
   val s2 = s1.append(Stream.cons(2, Stream.empty))
@@ -20,6 +27,11 @@ object Test extends App {
   println(s2.drop(2))
   println(s2.drop(-1))
   println(s2.dropWhile(_ > 0))
+  println(s2.lengthCompare(-5) > 0)
+  println(s2.lengthCompare(0) > 0)
+  println(s2.lengthCompare(1) > 0)
+  println(s2.lengthCompare(2) == 0)
+  println(s2.lengthCompare(5) < 0)
   println
 
   val s3 = Stream.range(1, 1000) //100000 (ticket #153: Stackoverflow)
@@ -43,4 +55,12 @@ object Test extends App {
   println(Stream.from(1).take(size).foldLeft(0)(_ + _))
   val arr = new Array[Int](size)
   Stream.from(1).take(size).copyToArray(arr, 0)
+
+  println
+
+  // ticket #6415
+  lazy val x = { println("evaluated"); 1 }
+  val s4 = 0 #:: x #:: Stream.empty
+
+  println(s4.isDefinedAt(0))
 }