Some hacks to make this compile with older dune versions and compilers

dune/fufem-forms/shapefunctioncache.hh

@@ -29,7 +29,17 @@ namespace Dune::Fufem::Forms::Impl {
     if constexpr (sizeof...(T)==0)
       return container;
     else
+#if DUNE_VERSION_GT(DUNE_TYPETREE, 2, 9)
       return accessByTreePath(container[path.front()], pop_front(path));
+#else
+    {
+      auto head = path[Dune::Indices::_0];
+      auto tailPath = Dune::unpackIntegerSequence([&](auto... i){
+                    return Dune::TypeTree::treePath(path[Dune::index_constant<i+1>{}]...);
+                  }, std::make_index_sequence<sizeof...(T)-1>());
+      return accessByTreePath(container[head], tailPath);
+    }
+#endif
   }
 
 

dune/fufem-forms/unaryoperators.hh

@@ -139,7 +139,7 @@ namespace Dune::Fufem::Forms {
         else if constexpr(Node::isPower and Node::ChildType::isLeaf)
           return [&](const auto& i) {
             using Field = typename LeafNode::FiniteElement::Traits::LocalBasisType::Traits::RangeFieldType;
-            constexpr auto components = Node::degree();
+            static constexpr auto components = Node::degree();
             auto componentIndex = i / leafNode_->size();
             auto shapeFunctionIndex = i % leafNode_->size();
             auto result = Dune::FieldVector<Field,components>(0);
@@ -230,8 +230,8 @@ namespace Dune::Fufem::Forms {
         return Dune::MetaType<LeafFEJacobian>();
       else if constexpr(Node::isPower and Node::ChildType::isLeaf)
       {
-        constexpr auto components = Node::degree();
-        constexpr auto dimension = LeafNode::FiniteElement::Traits::LocalBasisType::Traits::dimDomain;
+        static constexpr auto components = Node::degree();
+        static constexpr auto dimension = LeafNode::FiniteElement::Traits::LocalBasisType::Traits::dimDomain;
         return Dune::MetaType<Dune::FieldMatrix<LeafFERangeField,components,dimension>>();
       }
     }
@@ -439,7 +439,7 @@ namespace Dune::Fufem::Forms {
         if constexpr(Node::isLeaf)
           return [&](const auto& i) {
             using Field = typename LeafNode::FiniteElement::Traits::LocalBasisType::Traits::RangeFieldType;
-            constexpr auto dimension = LeafNode::FiniteElement::Traits::LocalBasisType::Traits::dimDomain;
+            static constexpr auto dimension = LeafNode::FiniteElement::Traits::LocalBasisType::Traits::dimDomain;
             auto div = Field{0};
             for(std::size_t j=0; j<dimension; ++j)
               div += globalJacobians[i][j][j];