Squelch a warning about unused variables

dune/fufem/hdf5/frombuffer.hh

@@ -29,9 +29,8 @@ void fromBuffer(std::vector<ctype> const &buffer, std::array<T, 3> dimensions,
 template <int k, typename ctype, typename T>
 void fromBuffer(std::vector<ctype> const &buffer, std::array<T, 2> &dimensions,
                 Dune::BlockVector<Dune::FieldVector<ctype, k>> &data) {
-  auto const entrySize = std::accumulate(dimensions.begin(), dimensions.end(),
-                                         1, std::multiplies<T>());
-  assert(buffer.size() == entrySize);
+  assert(buffer.size() == std::accumulate(dimensions.begin(), dimensions.end(),
+                                          1, std::multiplies<T>()));
   assert(dimensions[1] == k);
   data.resize(dimensions[0]);