SI-8917 collection.mutable.BitSet's &= operator doesn't clear end

Made &= run to the end of its own bitset, ignoring the size of what it's &-ing with (which is exactly what you want for &=).

1 files changed, 9 insertions, 0 deletions

diff --git a/test/junit/scala/collection/mutable/BitSetTest.scala b/test/junit/scala/collection/mutable/BitSetTest.scala
index 8d164b50d4..d56cc45601 100644
--- a/test/junit/scala/collection/mutable/BitSetTest.scala
+++ b/test/junit/scala/collection/mutable/BitSetTest.scala
@@ -19,4 +19,13 @@ class BitSetTest {
     bitSet &~= bitSet
     assert(bitSet.toBitMask.length == size, "Capacity of bitset changed after &~=")
   }
+  
+  @Test def test_SI8917() {
+    val bigBitSet = BitSet(1, 100, 10000)
+    val littleBitSet = BitSet(100)
+    bigBitSet &= littleBitSet
+    assert(!(bigBitSet contains 10000), "&= not applied to the full bitset")
+    littleBitSet &= bigBitSet
+    assert(littleBitSet.toBitMask.length < bigBitSet.toBitMask.length, "Needlessly extended the size of bitset on &=")
+  }
 }