QGIS » QGIS Application

I used QGIS recently and found out the there is certain situation i got two same snapping results from QgsSnapper. And i debugged a little, and found out a bug in the following place:

File : src/core/qgssnapper.cpp

Function : int QgsSnapper::snapMapPoint( const QgsPoint& mapCoordPoint, QList<QgsSnappingResult>& snappingResult, const QList<QgsPoint>& excludePoints )

The code :

QgsSnappingResult returnResult = evalIt.value();
  for ( evalIt = snappingResultList.begin(); evalIt != snappingResultList.end(); ++evalIt )
{
    if ( evalIt.value().snappedVertexNr != -1 )
  {
      returnResult = evalIt.value();
      snappingResultList.erase( evalIt );
      break;
    }
  }

//We return the preferred result
  snappingResult.push_back( returnResult );

if ( mSnapMode  QgsSnapper::SnapWithOneResult )
{
    //return only a single  result, nothing more to do
  }
  else if ( mSnapMode  QgsSnapper::SnapWithResultsForSamePosition )
{
    //take all snapping results within a certain tolerance because rounding differences may occur
    double tolerance = 0.000001;

for ( evalIt = snappingResultList.begin(); evalIt != snappingResultList.end(); ++evalIt )
{
      if ( returnResult.snappedVertex.sqrDist( evalIt.value().snappedVertex ) < tolerance*tolerance )
  {
        snappingResult.push_back( evalIt.value() );
      }
    }

}

else //take all results
{
    for ( evalIt = snappingResultList.begin(); evalIt != snappingResultList.end(); ++evalIt )
  {
      snappingResult.push_back( evalIt.value() );
    }
  }

The problem occurs when var 'snappingResultList' has no elements satisfied the condition :

if ( evalIt.value().snappedVertexNr != -1 )

And since the following code :

snappingResult.push_back( returnResult );

will push the first result(by QgsSnappingResult returnResult = evalIt.value();) anyway, and
when we under 'SnapWithResultsWithinTolerances' snap mode, we will get two duplicated elements!
And since the problem is obvious, so no test case provided.