Fix NPE caused by high index (zio#860)

7mind · May 26, 2019 · 28159aa · 28159aa
1 parent 1a4e7e4
commit 28159aa
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diff --git a/core/shared/src/main/scala/scalaz/zio/internal/StackBool.scala b/core/shared/src/main/scala/scalaz/zio/internal/StackBool.scala
@@ -32,7 +32,7 @@ private[zio] final class StackBool private () {
     var ie  = ((64L - i0) + index) >> 6
     var cur = head
 
-    while (ie > 0) {
+    while (ie > 0 && (cur ne null)) {
       ie -= 1
       cur = cur.next
     }

diff --git a/core/shared/src/test/scala/scalaz/zio/internal/StackBoolSpec.scala b/core/shared/src/test/scala/scalaz/zio/internal/StackBoolSpec.scala
@@ -10,6 +10,7 @@ class StackBoolSpec extends Specification with ScalaCheck {
         From/to list identity         $e1
         Push/pop example              $e2
         Peek/pop identity             $e3
+        GetOrElse index out of bounds $e4
     """
 
   import Arbitrary._
@@ -53,6 +54,12 @@ class StackBoolSpec extends Specification with ScalaCheck {
       }
     }
 
+  def e4 = {
+    val stack = StackBool()
+    val result = stack.getOrElse(100, true)
+    result must_=== true
+  }
+
   private def boolListGen(min: Int, max: Int) =
     for {
       size <- Gen.choose(min, max)