Trouble debugging some STL code

[address@hidden]

#include <iostream>
#include <map>
#include <set>
#include <iterator>
#include <algorithm>
#include <string>

std::ostream& operator << (std::ostream& o, const std::pair<std::string, int> p)
{
   o << p.first << " " << p.second << std::endl;
   return o;
}

std::ostream& operator << (std::ostream& o, const std::map<std::string,int>& 
map)
{
   typename std::map<std::string,int>::iterator it = map.begin();
   o << "(";
   while (it != map.end())
   {
      o << *it << ' ';
      ++it;
   }
   o << ")";
   return o;
}

int main()
{
   std::map<std::string,int> map;
   std::cout << "map=" << map << std::endl;
}


-----------------------------------------------------------------------------

Here is the compiler output:

-*- mode: compilation; default-directory: "~/lisp++-projects/" -*-
Compilation started at Thu Jan 25 18:45:22

cd ~/lisp++-projects && make 2018/map/map5.run
make: Warning: File '2006/libd/libd.o' has modification time 26862 s in the 
future
* Compiling 2018/map/map5.cc DEBUG
g++ -g -O0 -std=c++11 -W -Wall -Wpointer-arith -Wformat -ffast-math 
-fno-permissive -Wno-format-contains-nul -c 2018/map/map5.cc -o 2018/map/map5.o
2018/map/map5.cc: In function ‘std::ostream& operator<<(std::ostream&, const 
std::map<std::__cxx11::basic_string<char>, int>&)’:
2018/map/map5.cc:16:63: error: conversion from 
‘std::map<std::__cxx11::basic_string<char>, int>::const_iterator {aka 
std::_Rb_tree_const_iterator<std::pair<const std::__cxx11::basic_string<char>, 
int> >}’ to non-scalar type ‘std::map<std::__cxx11::basic_string<char>, 
int>::iterator {aka std::_Rb_tree_iterator<std::pair<const 
std::__cxx11::basic_string<char>, int> >}’ requested
    typename std::map<std::string,int>::iterator it = map.begin();
                                                               ^
Makefile.mk:66: recipe for target '2018/map/map5.o' failed
make: *** [2018/map/map5.o] Error 1

Compilation exited abnormally with code 2 at Thu Jan 25 18:45:24
Compilation started at: 20180125-184522
compilation-start-time=(23145 28402 353882 710000)
compilation-stop-time=(23145 28404 423781 491000)
Compilation took 2 seconds

What gives with the error message?  What mm I doing wrong?