ref is unsafe

[Jonathan M Davis]

On Wednesday, January 02, 2013 13:45:32 Maxim Fomin wrote:
> I think it should not be fixed, but probably compiler may issue
> warning at some circumstances when it can realize this situation.

It's a hole in @safe. It must be fixed. That's not even vaguely up for 
discussion. The question is _how_ to fix it. Ideally, it would be fixed in a way 
that limits how much more code has to become @system.

> By the way, there is another issue with ref -
> http://dpaste.dzfl.pl/928767a9 which was discussed several month
> ago minimum. Do you think this should be also fixed?

It's not a bug. You're dereferencing a null pointer, so you get a segfault. 
There's nothing surprising there.

> I don't take into D's @safity seriously because it can be easily
> hacked.

It's fine if you don't care about it, but as the maintainers of the language 
and standard library, we have to take it seriously. Regardless of the 
likelihood of there being a bug caused by this, it breaks @safe, so it must be 
fixed, even if that means simply making all functions which both accept by ref 
and return by ref @system. But that's very undesirable, because it will lead 
to too much code being considered @system even when it's perfectly safe. Hence 
why this is being discussed.

- Jonathan M Davis