message: Using static_cast instead of a const reference
diff: @@ -159,8 +159,7 @@ const double& BlockMatrix::Elem (int i, int j) const
  {
  mfem_error("BlockMatrix::Elem");
  }
  - const SparseMatrix& AijSM = *Aij(iblock, jblock);
  - return AijSM.Elem(iloc, jloc);
  + return static_cast<const SparseMatrix *>(Aij(iblock, jblock))->Elem(iloc, jloc);
  }
  int BlockMatrix::RowSize(const int i) const
  