C++ map segmentation fault (core dumped)

Question

I'm trying to use an map with string key, but it's not working and I couldn't figure out why. I would like to have some help to understand C++ fundamentals about the usage of this so essential structure.

model.hpp

#pragma once
#include <map>
#include <utility>
#include <string>
#include <iostream>
#include "../prs/ast.h"

using namespace std;
using namespace ast;

typedef map<string, Variable> Map;
typedef pair<string, Variable> Element;

namespace model{

    class Warehouse {
    public:
        Map stock;

        Warehouse(){
            Map* _stock = new Map();
            stock = *_stock;
        }

        Variable* get(string id){
            Map::iterator it = stock.find(id);
            if (it != stock.end()){
                return &(*it).second;
            }
            else {
                return __define__(id);
            }
        }

        Variable* __define__(string id){
            Variable* defined = new Variable(id);
            stock.insert(Element(id, *defined));
            return defined;
        }
    };

    static Warehouse* WAREHOUSE;
};

model.cpp

#pragma once
#include "model.hpp"

using namespace std;

namespace model {
    Warehouse* WAREHOUSE = new Warehouse();
}

In this context, Variable is a project object defined in ast namespace already tested, as well WAREHOUSE pointer is working accordingly, with class initialized

The instruction stock.find(id) is throwing the mentioned error message: Segmentation fault (core dumped) , what I suppose means stock isn't correct initialized.

What is exactly happening with stock initialization done at Warehouse constructor? I understand that new keyword alloc s the map and dereference its returned point would store the structure at stock Warehouse member attribute.

Am I misunderstand it?

Answer 1

WAREHOUSE is a static variable defined in a header. What this means is that every source file that includes that header gets its own copy of this variable, initialized to nullptr . Only one source file sets its own copy to a non-null value. Presumably, some other source file in the code not shown attempts to dereference its copy.

Make it

extern Warehouse* WAREHOUSE;