routing: Remove unused model_ member from Resource.

Author: Mizux

ortools/constraint_solver/routing.cc

@@ -1161,8 +1161,7 @@ ResourceGroup* RoutingModel::AddResourceGroup() {
 
 int ResourceGroup::AddResource(Attributes attributes,
                                const RoutingDimension* dimension) {
-  resources_.push_back(Resource(model_));
-  resources_.back().SetDimensionAttributes(std::move(attributes), dimension);
+  resources_.push_back({std::move(attributes), dimension});
 
   affected_dimension_indices_.insert(dimension->index());
 

ortools/constraint_solver/routing.h

@@ -448,13 +448,15 @@ class OR_DLL RoutingModel {
       }
 
      private:
-      explicit Resource(const RoutingModel* model) : model_(model) {}
+      Resource(ResourceGroup::Attributes attributes,
+               const RoutingDimension* dimension) {
+        SetDimensionAttributes(std::move(attributes), dimension);
+      }
 
       void SetDimensionAttributes(ResourceGroup::Attributes attributes,
                                   const RoutingDimension* dimension);
       const ResourceGroup::Attributes& GetDefaultAttributes() const;
 
-      const RoutingModel* const model_;
       absl::flat_hash_map<DimensionIndex, int> dimension_attributes_;
       util_intops::StrongVector<DimensionIndex, int>
           dimension_attributes_per_index_;