Run-Time Check Failure #0 ... on a method call

[noony]

Here is the error I get after calling a method (described below) :

Run-Time Check Failure #0 - The value of ESP was not properly saved across a function call. This is usually a result of calling a function declared with one calling convention with a function pointer declared with a different calling convention.

This is the code (simplified), the crash happend on line 49. I give some explainations after.

 
//-------------------------------------------------------------
class MyBaseClass 
{
 //...
};
 
//-------------------------------------------------------------
class MyInterface
{
  public:
    virtual void OnTrigger(NxActor* actor1, NxActor* actor2) = 0;
};
 
//-------------------------------------------------------------
class MyClass : public MyBaseClass, public MyInterface
{
public: 
 MyClass();   
 void OnTrigger(NxActor* actor1, NxActor* actor2);   // called from a subsystem 
                                                     // when an event is raised.
 
private:
  NxActor* m_actor; 
}
 
//-------------------------------------------------------------
MyClass::MyClass()
{
  m_actor = CreateActor();      // create an actor for a particular sub system
                                // (PhysX)
  m_actor.userData = this;      // hold the instance pointer to have a 1:1
                                // mapping between my instance and the actor 
                                // (userData is a void*)
}
 
//-------------------------------------------------------------
void MyClass::OnTrigger(Actor* actor1, Actor* actor2) 
{
}
 
//-------------------------------------------------------------
//  The subsystem event callback 
//-------------------------------------------------------------
void OnSubSystemTrigger(NxActor* actor1, NxActor* actor2)
{
   if (actor1.userData)
   {
       MyInterface* obj = (MyInterface*) actor1.userData;  // cast
       obj->OnTrigger(actor1, actor2);   // Call the method.Here is the crash
   }
}

- I checked if the value of userData didn't change between the constructor and the call. It is the same (eg : 0x0055c108).

- Just after the cast, obj is not valid "inside". When I use the VStudio watch on <MyInterface* obj> (line45) I get messy values :

   - MyInterface obj  0x0055c108
     - MyClass
       - MyBaseClass
            __vfptr    0xfdfdfdfd    *
       - MyInterface
       - _actor    0x00000065 {userData=??? }    NxActor *

- And finally I get no error if iswitch the inheritance order from :
class MyClass : public MyBaseClass, public MyInterface
to :
class MyClass : public MyInterface, public MyBaseClass

Any idea ?

Thanks!

[weaknessforcats]

1) You are not calling your base class constructors in the MyClass constructor. That is, you need an intialization list where you call the base class constructors. The automatci calling of base class constructors has been disabled for multiple inheritance. This was done to prevent common base classes from having their constructors called multiple times.

2) Ditch that void*. A void* in C++ manes your calling a relci C function ir b) ytour design is screwed up.

3) You never cast in C++ as part of your normal coding style. If the C++ compiler cannot figure out your type, then you have real problems. If you need to be in charge of things, switch to C where nothing is done to help you.