Access violation on std::function assignement using lambdas

问题

Hy everyone, here again. Continuing the code from my previous question : Is this a bad hack? memcpy with virtual classes I corrected that, using the Clone approach as suggested, but I'm having an error that also happened before I tried the memcpy thing(read question above).

What I'm trying to do is to create a lambda that captures the current script and executes it, and then pass and store that lambda in an object ( Trigger*), in the member InternalCallback.
I get an access violation error on the lambda assignment: http://imgur.com/OKLMJpa The error happens only at the 4th iteration of this code:

if(CheckHR(EnginePTR->iPhysics->CreateFromFile(physicsPath,StartingTriggerID,trans,scale,-1,false,engPtr)) == HR_Correct)
{
     _Lua::ScriptedEntity * newScript = EntityBase->Clone(vm);//nullptr;

     string luaPath = transforms.next_sibling().next_sibling().first_attribute().as_string();
     if(UseRelativePaths)
     { 
         stringstream temp2;
         temp2 << _Core::ExePath() << LuaSubfolder << "\\" << luaPath;
         luaPath = temp2.str();
     }

     newScript->CompileFile(luaPath.c_str());
     newScript->EnginePTR_voidptr = engPtr;

     auto callback = [=](_Physics::Trigger* trigger,PxTriggerPair* pairs, PxU32 count) 
                        {
                            newScript->SelectScriptFunction("TriggerCallback");
                            newScript->AddParam(trigger->Id);

                            auto data = (_Physics::RayCastingStats*)pairs->otherShape->userData;

                            newScript->AddParam((PxU8)pairs->flags);
                            newScript->AddParam(data->ID);
                            newScript->AddParam((int)data->Type);

                            newScript->AddParam((int)count);

                            newScript->Go(1);

                            return;
                        };

     ((_Physics::Trigger*)EnginePTR->iPhysics->GetPhysicObject(StartingTriggerID))->InternalCallback = callback;

     StartingTriggerID++;
}

This is the code for Trigger

class Trigger : public PhysicObject
    {
    public:
        Trigger()
        {
            ActorDynamic = nullptr;
            ActorStatic = nullptr;
            InternalCallback = nullptr;
        }
        virtual HRESULT Update(float ElapsedTime,void * EnginePTR);
        virtual HRESULT Cleanup(); // Release the actor!!

        long Id;
        ShapeTypes Type;
        static const PhysicObjectType PhysicsType = PhysicObjectType::Trigger;
        PxVec3 Scale;

        void* UserData;
        void Callback(PxTriggerPair* pairs,PxU32 count)
        {
            InternalCallback(this,pairs,count);
        }

        function<void(_Physics::Trigger* trigger,PxTriggerPair* pairs, PxU32 count)> InternalCallback;
    };

By iteration I mean that is part of a for loop. My system is Win 7 64 bits, Intel i3, NVIDIA GTX 480, and the compiler Visual Studio 2012 Express, using the C++11 toolset. I'm really out of ideas. I tested for heap corruption, it appears to be good, I changed the capture in the lambda, changed nothing, I skip the 4th object and it works. Any help would be really appreciated.

Edit: As required, here is the callstack: http://imgur.com/P7P3t4k

回答1:

Solved. It was a design error. I store a lot of objects in a map, and they all derive from an object class ( like above, where Trigger derives from PhysicObject ). The problem was that I was having IDs collisions, so the object stored in ID 5 wasn't a Trigger, so the cast created a bad object, and so the program crashed.

Silly error, really specific, but it might help somebody to remember to check temporal objects.

来源：https://stackoverflow.com/questions/16888827/access-violation-on-stdfunction-assignement-using-lambdas