#include <iostream>
#include <hash_map>


using namespace std;

template<class T>
class HashData
{
    public:
        hash_map<T, HashData<T>, hash<T>, equal_to<T> >::iterator it;

};


int main()
{
    HashData<int> bob;

    return 0;
}

Errors:

stl_pair.h: In instantiation of 'pair<const int, HashData<int> >':

stl_hashtable.h:239:  instantiated from '_Select1st<pair<const int,HashData<int> > >'

stl_hashtable.h:239:  instantiated from 'hashtable.h:239:  instantiated from 'hashtable<pair<const int,HashData<int> >,int,hashallocator<HashData<int> > >'

test.cpp:11:  instantiated from 'HashData<int>'
test.cpp:18:  instantiated from here

stl_pair.h:39: invalid use of undefined type 'class HashData<int>'
test.cpp:13: forward declaration of 'class HashData<int>'
stl_pair.h:50: confused by earlier errors, bailing out