About structs and performant handling

[Namespace]

> Finally, I think this behavior is very dangerous. Pass by 
> reference and value have very different. With that construct, 
> you'll never know which one you get as the compiler decide ! If 
> the compiler and not the programmer decide what the program 
> does (not implementation wise, but semantically), we have a 
> problem.

Haven't you then not the same problems with 'auto ref'?
But you could prohibit any manipulation of a '&' parameter. Eg. 
you could make him 'scope' by default (if 'scope' will work 
someday).