SI-7128 copyToArray(xs, 0, 0) should not fail

Fixed all copyToArray methods to do exactly what the docs say
they do, with the least-suprise behavior of not throwing an
exception if you ask to copy nothing (but would have copied out of
range).

Iterator had an undocumented requirement for the target index to
be in range regardless if anything happened; this has been removed.

2 files changed, 26 insertions, 6 deletions

diff --git a/test/files/run/t6827.check b/test/files/run/t6827.check
index 3a3a71c67d..4889e05be8 100644
--- a/test/files/run/t6827.check
+++ b/test/files/run/t6827.check
@@ -1,6 +1,6 @@
-start at -5: java.lang.IllegalArgumentException: requirement failed: start -5 out of range 10
-start at -1: java.lang.IllegalArgumentException: requirement failed: start -1 out of range 10
-start at limit: java.lang.IllegalArgumentException: requirement failed: start 10 out of range 10
+start at -5: java.lang.ArrayIndexOutOfBoundsException: -5
+start at -1: java.lang.ArrayIndexOutOfBoundsException: -1
+start at limit: ok
 start at limit-1: ok
 first 10: ok
 read all: ok
@@ -8,8 +8,8 @@ test huge len: ok
 5 from 5: ok
 20 from 5: ok
 test len overflow: ok
-start beyond limit: java.lang.IllegalArgumentException: requirement failed: start 30 out of range 10
+start beyond limit: ok
 read 0: ok
 read -1: ok
-invalid read 0: java.lang.IllegalArgumentException: requirement failed: start 30 out of range 10
-invalid read -1: java.lang.IllegalArgumentException: requirement failed: start 30 out of range 10
+invalid read 0: ok
+invalid read -1: ok
diff --git a/test/files/run/t6827.scala b/test/files/run/t6827.scala
index 8e17af09e2..eb020711bb 100644
--- a/test/files/run/t6827.scala
+++ b/test/files/run/t6827.scala
@@ -31,4 +31,24 @@ object Test extends App {
 
   // okay, see SI-7128
   "...".toIterator.copyToArray(new Array[Char](0), 0, 0)
+
+
+  // Bonus test from @som-snytt to check for overflow in
+  // index calculations.
+  def testOverflow(start: Int, len: Int, expected: List[Char]) {
+    def copyFromIterator = {
+      val arr = Array.fill[Char](3)('-')
+      "abc".toIterator.copyToArray(arr, start, len)
+      arr.toList
+    }
+    def copyFromArray = {
+      val arr = Array.fill[Char](3)('-')
+      "abc".toArray.copyToArray(arr, start, len)
+      arr.toList
+    }
+    assert(copyFromIterator == expected)
+    assert(copyFromArray == expected)
+  }
+  testOverflow(1, Int.MaxValue - 1, "-ab".toList)
+  testOverflow(1, Int.MaxValue, "-ab".toList)
 }