shared_ptr use_count corruption

[tripleslash]

Luabind causes a shared_ptr corruption when you do this in lua:

local gSharedObject = nil;
function Testfunction()
    gSharedObject = SharedObject.Create();
    return gSharedObject;
end

where the C++ export looks like that:

class SharedObject {
public:
    SharedObject() {}

    static boost::shared_ptr<SharedObject> Create() {
        return boost::make_shared<SharedObject>();
    }
}

luabind::module(L) [
    luabind::class_<SharedObject, boost::shared_ptr<SharedObject>>("SharedObject")
        .scope [ luabind::def("Create", &SharedObject::Create) ]
];

Now when you do the following you will get a use_count == 1 where it should actually be 2 because lua should hold a shared_ptr and your code should:

boost::shared_ptr<SharedObject> obj = luabind::call_function<boost::shared_ptr<SharedObject>>(L, "Testfunction");
std::cout << obj.use_count() << std::endl;
// prints 1 but should actually be 2, one from the current scope and one in lua globals, because the lua state is still alive... ?!?

This is a huge problem when your GC runs because it always thinks the shared_ptr is the only one in use and it will always release objects created like that, not matter if a ptr is used by the c++ code atm.

Example:

boost::shared_ptr<SharedObject> obj = luabind::call_function<boost::shared_ptr<SharedObject>>(L, "Testfunction");
std::cout << obj.use_count() << std::endl;

lua_close(L); // invokes ~SharedObject -_-

std::cout << obj.use_count() << std::endl; // still 1

The problem exists in lua 5.1 and 5.2, everywhere I checked