[LUCENE-6427] BitSet fixes - assert on presence of 'ghost bits' and others

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 5.2, 6.0
• Component/s: core/other
• Lucene Fields: New
• Assignee: Unassigned
• Reporter: Luc Vanlerberghe
• Created: 15/Apr/15 14:11
• Updated: 09/May/16 18:30
• Resolved: 28/Apr/15 20:45

Description

Fixes after reviewing org.apache.lucene.util.FixedBitSet, LongBitSet and corresponding tests:

• Some methods rely on the fact that no bits are set after numBits (what I call 'ghost' bits here).
  • cardinality, nextSetBit, intersects and others may yield wrong results
  • If ghost bits are present, they may become visible after ensureCapacity is called.
  • The tests deliberately create bitsets with ghost bits, but then do not detect these failures
• FixedBitSet.cardinality scans the complete backing array, even if only numWords are in use