Field `first` could not be resolved using map c++

Question

I have the following code in a header file:

#include <string>
using std::string;
#include <map>
using std::map;
#include <utility>
using std::pair;
#include "share.h"
#include "bond.h"
#include "projectEnumsDefines.h"

namespace mtm {

class Account {
    string id;
    double money;
    RequestType type;
    map<share, int> shares;
    map<bond, int> bonds;

public:
    void checkBondsAndUpdate() {
        for(auto &it1 : bonds) {
            bond bond =  it1.first;

    }
}
// class implementation
};
}

i'm trying to access the bond keys in checkBondsAndUpdate by iterating on the "bonds" map. however on the line "bond bond = it1.first;" it given an error "Field first could not be resolved". what could be the problem here? thanks

EDIT: it works if i do

pair<bond,int> pair =  it1;
bond bond = pair.first;

instead of

bond bond =  it1.first;

the only question is why..