Why does nobody seem to think that `null` is a serious problem in D?

[Timon Gehr]

On 22.11.18 16:19, Steven Schveighoffer wrote:
> 
> In terms of language semantics, I don't know what the right answer is. 
> If we want to say that if an optimizer changes program behavior, the 
> code must be UB, then this would have to be UB.
> 
> But I would prefer saying something like -- if a segfault occurs and the 
> program continues, the system is in UB-land, but otherwise, it's fine. 
> If this means an optimized program runs and a non-optimized one crashes, 
> then that's what it means. I'd be OK with that result. It's like 
> Schrodinger's segfault!
> 
> I don't know what it means in terms of compiler assumptions, so that's 
> where my ignorance will likely get me in trouble :)

This is called nondeterministic semantics, and it is a good idea if you 
want both efficiency and memory safety guarantees, but I don't know how 
well our backends would support it.

(However, I think it is necessary anyway, e.g. to give semantics to pure 
functions.)