Nested foreach generate warnings

With the use of nested foreach, we obtain the following warning:

warning C4456: declaration of '_container_' hides previous local declaration

This is obtained with the following code:

QList<int> aList;
QList<int> bList;
foreach(int a, aList)
{
  Q_UNUSED(a);
  foreach(int b, bList)
  {
    Q_UNUSED(b);
  }
}

I'm using Visual Studio 2015 update 3, with the .Net framework 4.7.02556

This warning becomes an issue when we activate the warnings as error, to guaranty a clean code.