Program: 74341
Project: 74341
Buggy source:
private boolean _matchList(LookbackEntry matchedObjectLists){
  ObjectList patternList=matchedObjectLists.getPatternList();
  ObjectList hostList=matchedObjectLists.getHostList();
  int matchSize=_matchResult.size();
  boolean success=true;
  boolean patternChildChecked=false;
  boolean firstEntrance=!_matchResult.containsKey(patternList);
  FastLinkedList<LookbackEntry>.Entry lookbackTail=null;
  if (firstEntrance) {
    _matchResult.put(patternList,hostList);
    _lookbackList.add(matchedObjectLists);
    lookbackTail=_lookbackList.getTail();
  }
  ObjectList.Entry patternEntry=patternList.getHead();
  Object patternObject=null;
  while (patternEntry != null) {
    patternObject=patternEntry.getValue();
    if (_negation == _isNegated(patternObject) && !_isIgnored(patternObject)) {
      break;
    }
    patternEntry=patternEntry.getNext();
  }
  boolean optional=false;
  if (patternEntry != null) {
    ObjectList.Entry previous=patternEntry.getPrevious();
    patternEntry.remove();
    optional=_isOptional(patternObject);
    if (optional && !_ignoredOptionalObjects.containsKey(patternObject)) {
      _ignoredOptionalObjects.put(patternObject,false);
    }
 else {
      optional=false;
    }
    patternChildChecked=true;
    success=false;
    ObjectList.Entry hostEntryPrevious=null;
    ObjectList.Entry hostEntry=hostList.getHead();
    while (hostEntry != null) {
      hostEntry.remove();
      Object hostObject=hostEntry.getValue();
      if (_matchObject(patternObject,hostObject)) {
        success=true;
      }
      hostList.addEntryAfter(hostEntry,hostEntryPrevious);
      if (success) {
        break;
      }
      hostEntryPrevious=hostEntry;
      hostEntry=hostEntry.getNext();
    }
    patternList.addEntryAfter(patternEntry,previous);
  }
  if (success) {
    if (!patternChildChecked) {
      if (_negation) {
        matchedObjectLists.setNegated(true);
      }
 else {
        matchedObjectLists.setFinished(true);
      }
      success=_checkBackward();
      if (_negation) {
        matchedObjectLists.setNegated(false);
      }
 else {
        matchedObjectLists.setFinished(false);
      }
    }
  }
  if (success == _negation) {
    if (!success || optional) {
      _matchResult.retain(matchSize);
    }
    if (optional) {
      _ignoredOptionalObjects.put(patternObject,true);
      ObjectList.Entry previous=patternEntry.getPrevious();
      patternEntry.remove();
      success=_checkBackward();
      patternList.addEntryAfter(patternEntry,previous);
    }
  }
  if (firstEntrance) {
    lookbackTail.remove();
  }
  if (optional) {
    _ignoredOptionalObjects.remove(patternObject);
  }
  return success;
}

Fixed version (ground truth):
private boolean _matchList(LookbackEntry matchedObjectLists){
  ObjectList patternList=matchedObjectLists.getPatternList();
  ObjectList hostList=matchedObjectLists.getHostList();
  int matchSize=_matchResult.size();
  boolean success=true;
  boolean patternChildChecked=false;
  boolean firstEntrance=!_matchResult.containsKey(patternList);
  FastLinkedList<LookbackEntry>.Entry lookbackTail=null;
  if (firstEntrance) {
    _matchResult.put(patternList,hostList);
    _lookbackList.add(matchedObjectLists);
    lookbackTail=_lookbackList.getTail();
  }
  ObjectList.Entry patternEntry=patternList.getHead();
  Object patternObject=null;
  while (patternEntry != null) {
    patternObject=patternEntry.getValue();
    if (_negation == _isNegated(patternObject) && !_isIgnored(patternObject)) {
      break;
    }
    patternEntry=patternEntry.getNext();
  }
  NamedObj optionalContainer=null;
  if (patternEntry != null) {
    ObjectList.Entry previous=patternEntry.getPrevious();
    patternEntry.remove();
    if (patternObject instanceof NamedObj) {
      optionalContainer=_getOptionalContainer((NamedObj)patternObject);
      if (optionalContainer != null && !_ignoredOptionalObjects.containsKey(optionalContainer)) {
        _ignoredOptionalObjects.put(optionalContainer,false);
        _clearCaches();
      }
 else {
        optionalContainer=null;
      }
    }
    patternChildChecked=true;
    success=false;
    ObjectList.Entry hostEntryPrevious=null;
    ObjectList.Entry hostEntry=hostList.getHead();
    while (hostEntry != null) {
      hostEntry.remove();
      Object hostObject=hostEntry.getValue();
      if (_matchObject(patternObject,hostObject)) {
        success=true;
      }
      hostList.addEntryAfter(hostEntry,hostEntryPrevious);
      if (success) {
        break;
      }
      hostEntryPrevious=hostEntry;
      hostEntry=hostEntry.getNext();
    }
    patternList.addEntryAfter(patternEntry,previous);
  }
  if (success) {
    if (!patternChildChecked) {
      if (_negation) {
        matchedObjectLists.setNegated(true);
      }
 else {
        matchedObjectLists.setFinished(true);
      }
      success=_checkBackward();
      if (_negation) {
        matchedObjectLists.setNegated(false);
      }
 else {
        matchedObjectLists.setFinished(false);
      }
    }
  }
  if (success == _negation) {
    if (!success || optionalContainer != null) {
      _matchResult.retain(matchSize);
    }
    if (optionalContainer != null) {
      _ignoredOptionalObjects.put(optionalContainer,true);
      _clearCaches();
      ObjectList.Entry previous=patternEntry.getPrevious();
      patternEntry.remove();
      success=_checkBackward();
      patternList.addEntryAfter(patternEntry,previous);
    }
  }
  if (firstEntrance) {
    lookbackTail.remove();
  }
  if (optionalContainer != null) {
    _ignoredOptionalObjects.remove(optionalContainer);
    _clearCaches();
  }
  return success;
}