Question

thank you for looking at my problem.

I have an object that is being dynamically created in my program. The creation is part of a loop and the first iteration works fine.

Upon creation, my object base class adds itself to a map.

Here is some sample code :

public class Base {  
    Base() {
        // Add itself to a map
        Data::objects[key] = this;
    }
}

public class Derived : public Base {
    // This ctor only initialize one int field.
    Derived() : Base() {};
}

Kinda simple isn’t it ?

In my code, I do Derived * d = new Derived(); and for some silly reason, I get a SIGSEGV.

I tried to debug it, but it doesn’t even enters the ctor before crashing!

Here is my call stack so you can help me better:

Address: @0x002c0000
ntdll!RtlReleasePebLock()
Address: @0x0000000c at c:…\stl_deque.h:514
msvrct!malloc()
libstdc++-6!_Znwj()
fu87_ZSt4cerr(this=0xbc1ad8, e=”//my object name//”) at //my object name//.cpp
… Other are my lines.

Thank you, Micael

{enjoy}

Edit: Adding informations about the map

The map is located in a data class, statically.

// Data.h
class Data {
    static map<int, Base*> objects;
}

// Data.cpp
#include "Data.h"
map<int, Base*> Data::objects;

// methods implementations

How can you corrupt the heap, how can I find a corruption has occured?

Answer 1

Has Data::objects been initialized prior to the creation of ANY of the usages of Base?

You are not guaranteed that the class object objects had been initialized whenever you have more than one translation unit (read, .cpp file) in the final link target, unless you’ve gone to special effort to ensure it.

Most people solve this problem by using a static class through which this initialization is guaranteed to have occurred on first use. Something like:

// untested code, typed in by hand, not compiled through a machine compiler.
class Base {
    public: static addObject(Base* that);
    Base::Base() { Base::addObject(this); }
};
class Derived: public Base {
    Derived::Derived() {}
};
//
// and in the .CPP for Base
namespace /* hidden */ {
    int object_number = 0;
    map<int,Base*> *objects = NULL;
}
void Base::addObject(Base* that) {
    // TODO: do something to avoid multi-thread issues if that is ever a concern
    if (!objects) {
        objects = new map<int,Base*>();
    }
    (*objects)[++object_number] = that;
}