Fix compilation without dune-parmg

dune/elasticity/common/trustregionsolver.cc

@@ -248,11 +248,11 @@ void TrustRegionSolver<BasisType,VectorType>::solve()
     BasisType basis(grid_->levelGridView(grid_->maxLevel()));
     BasisType coarseBasis(grid_->levelGridView(0));
     std::vector<BoxConstraint<typename VectorType::field_type, blocksize>> coarseTrustRegionObstacles(coarseBasis.size());
-    MaxNormTrustRegion<blocksize> trustRegion(basis.size(), initialTrustRegionRadius_);
     int numLevels = grid_->maxLevel()+1;
 
     auto& levelOp = mgSetup_->levelOps_;
 #endif
+    MaxNormTrustRegion<blocksize> trustRegion(basis.size(), initialTrustRegionRadius_);
 
     std::vector<BoxConstraint<field_type,blocksize> > trustRegionObstacles;
 

dune/elasticity/common/trustregionsolver.hh

@@ -21,6 +21,7 @@
 
 #include <dune/elasticity/assemblers/feassembler.hh>
 
+#if HAVE_DUNE_PARMG
 #include <dune/parmg/iterationstep/lambdastep.hh>
 #include <dune/parmg/iterationstep/multigrid.hh>
 #include <dune/parmg/parallel/dofmap.hh>
@@ -31,7 +32,7 @@
 #include <dune/parmg/parallel/parallelenergyfunctional.hh>
 #include <dune/parmg/parallel/parallelenergynorm.hh>
 #include <dune/parmg/parallel/restrictmatrix.hh>
-
+#endif
 
 
 /** \brief Trust-region solver  */