Why is Visual Studio using std::iterator<> instead of mine::iterator<>

I've been trying to figure out this problem for a couple days now and finally figured it out after striping everything down to the code below. You'll see in the code below three different attempts at a constructor for const_iterator, along with the errors I get on two of them. It appears to me that the compiler is trying to use std::iterator instead of the locally declared mine::iterator. Is it supposed to be that way?

Other tidbits that have given clues:

If I name mine::iterator something else, like mine::B, then const_iterator(const B &rhs) works.
If I derive const_iterator from a class other than std::iterator, then const_iterator(const iterator<T> &rhs) works.

Thanks for any info. Here's the code:

#include "stdafx.h"
#include <iterator>

namespace mine 
{

   template <class T>
   class iterator : public std::iterator<std::random_access_iterator_tag, T, ptrdiff_t, T*, T&>
   {
   public:
      iterator() {}
   };   

   template <class T>
   class const_iterator : public std::iterator<std::random_access_iterator_tag, T, ptrdiff_t, const T*, const T&>
   {
   public:
      const_iterator() {} 
      const_iterator(const mine::iterator<T> &rhs) {} // works
      //const_iterator(const iterator &rhs)        {} // error C2440: initializing: cannot convert from 'mine::iterator<T>' to 'mine::const_iterator<T>'
      //const_iterator(const iterator<T> &rhs)     {} // error C2976: std::iterator: too few template arguments
   }; 

}// namespace mine

using namespace mine;

int _tmain(int argc, _TCHAR* argv[])
{
   iterator<int> y;
   const_iterator<int> x = y;

   return 0;
}

Solution

First of all 'using namespace' is evil, use typedef for ease of use. for example instead of saying iterator use mine::iterator.

Also your second point gives the answer of your question. "If I derive const_iterator from a class other than std::iterator, then const_iterator(const iterator<T> &rhs) works."

Here the nearest iterator belongs to std not mine, as std::iterator is the base class of your const_iterator.