resolved a clang error

dune/vtk/vtkwriterinterface.impl.hh

@@ -289,8 +289,8 @@ std::uint64_t VtkWriterInterface<GV,DC>
 
   pos_type end_pos = out.tellp();
   if (format_ == Vtk::COMPRESSED) {
-    out.seekp(begin_pos + std::int64_t(3*sizeof(std::uint64_t)));
-    out.write((char*)cbs.data(), num_blocks*sizeof(std::uint64_t));
+    out.seekp(begin_pos + std::streamoff(3*sizeof(std::uint64_t)));
+    out.write((char*)cbs.data(), std::streamsize(num_blocks*sizeof(std::uint64_t)));
     out.seekp(end_pos);
   }
 

src/vectorwriter.cc

@@ -12,13 +12,8 @@
 #include <dune/common/parallel/mpihelper.hh> // An initializer of MPI
 #include <dune/common/exceptions.hh> // We use exceptions
 
-#include <dune/functions/functionspacebases/defaultglobalbasis.hh>
-#include <dune/functions/functionspacebases/lagrangebasis.hh>
-#include <dune/functions/functionspacebases/interpolate.hh>
 #include <dune/functions/gridfunctions/analyticgridviewfunction.hh>
-#include <dune/functions/gridfunctions/discreteglobalbasisfunction.hh>
 #include <dune/grid/yaspgrid.hh>
-
 #include <dune/vtk/vtkwriter.hh>
 
 using namespace Dune;
@@ -37,9 +32,6 @@ static TestCases test_cases = {
 template <class GridView>
 void write (std::string prefix, GridView const& gridView)
 {
-  using namespace BasisFactory;
-  auto basis = makeBasis(gridView, lagrange<1>());
-
   FieldVector<double,GridView::dimensionworld> c;
   if (GridView::dimensionworld > 0) c[0] = 11.0;
   if (GridView::dimensionworld > 1) c[1] = 7.0;