@trusted and return ref

[via Digitalmars-d-learn]

On Friday, 27 February 2015 at 09:33:43 UTC, Kagamin wrote:
> If you can't give an example of unsafety easily, that's already 
> quite important. Compare to C, where one can provide such an 
> example easily.

Yes, that is true. Also, if you are conservative in C++ you also 
get pretty good safety with unique_ptr etc. So weak memory safety 
is ok, but then I also think it is ok to provide @trusted 
convenience since you are already saying that the programmer is 
competent:

unsafe_malloc!T()
unsafe_free!T()
unsafe_memmove!T()
unsafe_mmap…

> If you want to write a mathematical prover, that won't hurt, 
> though such tools don't need language support, lints and 
> provers were written even for C.

Yep. But what I meant is that a type system (including memory 
safety) ought to be proven sound. I.e:

1. You construct a simple language/type-system P and prove that P 
is sound and safe.
2. You construct a transform T(x) that can transform language D 
into x.

=> D is proven safe.