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Aniket_P_1
Beginner
356 Views

implicitly generated assignment operator cannot copy reference member

icpc error implicitly generated assignment operator cannot copy reference member (boost graph)

 

compiler: icc 13.0.1 / c++11 support

I am using a `boost::filter_iterator` to filter over of a pair of boost graph vertices as follows:

I have a range of graph vertices using a `vertex_iterator` pair `<vbegin, vend>.`
I want to filter the range using a predicate and the range needs to be grouped
into say 4 sub-ranges

    <begin1, end1> ... <begin4, end4>

So I filter over the vertex iterator using `boost::filter_iterator` and create 4 subranges.
Such subrange iterator pairs need to be inserted into a container (vector)
   
    std::vector< pair<filter_iterator, filter_iterator> >  my_vector
    size of vector = 4 (because 4 pairs are inserted)

A filter predicate with a given desired parameter helps define the filter iterator range

    <fbegin, fend>

The code is as below :

     template<typename Graph>
     struct my_filter_pred {
       public:
         my_filter_pred() { }  
         my_filter_pred(Graph& _G, int _value) : G(_G), value(_value) {  }
 
         template<typename vertex_t>
         bool operator() (vertex_t vertex) {

            //get property "p" of vertex in graph G
            auto p = get (mypropertytype, vertex, G);
            return (p.val == value);
         }

         private:
          Graph& G;
        }

      //get all vertices using vertex iterator
      vertex_iterator  vbegin, vend;
      boost::tie(vbegin, vend) = boost::vertices(G);

The for - loop is as below"

      //for each i = 0,1,2,3 -> create a predicate with i as parameter.
      //apply the filter predicate over the vertex_iterator range
      //insert in the begin, end pair into vector

      for (int i=0; i<4; ++i)
      {
        //for each i, create a filter_pred
        my_filter_pred <Graph> filter_pred(G, i)
        
        //now create begin and end filter iterators as follows
        auto fbegin = boost::make_filter_iterator< my_filter_pred<Graph>,
                                           vertex_iterator>   (filter_pred, vbegin, vend)
        auto fend = boost::make_filter_iterator< my_filter_pred<Graph>,
                                           vertex_iterator>   (filter_pred, vend, vend)
        
        //fbegin, fend are of type filter iterator
        //insert the iterator pair into vector
        my_vector.push_back( std::make_pair (fbegin, fend) );
       }

Now: the problem testing part:

I am using 2 compilers gcc4.9 and Inter 13.0.1 for testing this code.

Results :
     
    gcc 4.9 --> works correctly, compiles fine and works fine as well.
    icpc gives me the following error:
      
       error: implicitly generated assignment operator cannot copy:
            reference member "my_filter_pred <Graph>::G [with ... ]"
  struct my_filter_pred {
         ^
          detected during:implicit generation of "my_filter_pred<Graph> &my_filter_pred<Graph>::operator=(const my_filter_pred<Graph> &)" at line ...


How do I solve this ? I tried adding the following into my predicate (function object)

       my_filter_pred& operator=(const my_filter_pred&);
       my_filter_pred(const my_filter_pred&);
     

but after that I get "undefined reference to .... " error. How do I explicitly define the copy assignment operator and copy constructor

with gcc 4.9/ 4.7 its working. but I get errors for intel compiler 13.0.1, I am using C++11

 

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2 Replies
emmanuel_attia
Beginner
356 Views

   my_filter_pred& operator=(const my_filter_pred&);

       my_filter_pred(const my_filter_pred&);

Did you provide a definition for them ?

Aniket_P_1
Beginner
356 Views

yes. i did provide it. again i got the error pointing to the base filtered graph ( I was using filtered graph as by graph type)

it turned out that i had to use the following to remove the error:

    struct my_filter_pred {
       public:
         my_filter_pred() { }  
         my_filter_pred(Graph& _G, int _value) : G(&_G), value(_value) {  }

         template<typename vertex_t>
         bool operator() (vertex_t vertex) {
            //get property "p" of vertex in graph G
            auto p = get (mypropertytype, vertex, *G);
            return (p.val == value);
         }
         private:
           Graph* G;
    };

 

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