QueuePtr | Intrusive Ptr a buffer pool | Reflection library

You're doing an often sensible thing here: The struct is only defined in your implementation of the queue. This makes sure no other module can ever depend on the inner workings of your struct, so you can change it without touching any external code.

But in your main(), you try to do what you explicitly forbid: accessing the content of your struct. It's impossible because the compiler doesn't know the content when compiling your main file.

You have two options:

1. Move the definition of the struct to your header file, therefore making it public.

2. (IMHO preferred): Provide an accessor method like