// `0x123` means the address of the object.

weakref<X> active(0x123);
free(0x123);     // cache.push_back(0x123)  And weakflag.Set(true)
0x123 = alloc(); // 0x123 = cache.pop_back()
weakref<X> tmp(0x123);

active = tmp; // Assignment is not executed because it is the following code

// weakref.cpp: ::operator =(const CScriptWeakRef &other)
//     // Don't do anything if it is the same reference
//     if( m_ref == other.m_ref )
//       return *this;

if( active.get() is null ) {
  println("is null!!!!");
}

I believe you're correct in your observation. The fact that the address is the same doesn't necessarily mean that it is the same object instance. Especially for the weakref that doesn't force the first object instance to stay alive.

I'll have it fixed.

Thanks for reporting it.

I've fixed this in revision 2483.