I am having really tough time finding anywhere on the web
concrete explanation (if any) of how Garbage Colletor
decided for C++ managed objects when object is ready to be
released, and why?  Refer to simple example below with
questions inside comments.

__gc public class MyGCClass
{
    ...
}

void main()
{
    simple_unmanaged_function();
}

void simple_unmanaged_function()
{
    int x = 0;
    MyGCClass* obj = new MyGCClass();
    obj->DoSomething();

    //  Can GC release the MyGCClass instance
    // at this point, if it is not being used
    // until the end of the function?
    //  Must GC postpone collecting the instance
    // until obj reference to goes out of
    // of scope?  i.e. for function to return
    //  What if different optimizations are
    // set in "project"->"Property"->
    // "c/c++"->"Optimizations"?
    //
   
    x = 5;
   
    //  Is this (set to NULL) necessary to
    // mark obj as not referencing and
    // available for GC?
    //  Or going out of scope is sufficient?  
    // obj = NULL;
    //  Seems to work without setting obj to NULL,
    // but I just want to know what is good
    // practice and why...
}

Thank you,
-Boris