Avoid signed/unsigned warning

dune/elasticity/assemblers/feassembler.hh

@@ -119,18 +119,18 @@ assembleGradientAndHessian(const VectorType& configuration,
     Matrix<field_type> localHessian;
     localHessian.setSize(size, size);
 
-    for (int i=0; i<size; i++)
+    for (size_t i=0; i<size; i++)
       localConfiguration[i] = configurationBackend[ localView.index(i) ];
 
     // setup local matrix and gradient
     localStiffness_->assembleGradientAndHessian(localView, localConfiguration, localGradient, localHessian);
 
-    for(int i=0; i<size; i++)
+    for (size_t i=0; i<size; i++)
     {
       auto row = localView.index(i);
       gradientBackend[row] += localGradient[i];
 
-      for (int j=0; j<size; j++ )
+      for (size_t j=0; j<size; j++ )
       {
         auto col = localView.index(j);
         // fufem ISTLBackend uses operator() for entry access