Re: C aggregate passing (Rust kernel policy)

[Ventura Jack <venturajack85@gmail.com>]

On Thu, Feb 27, 2025 at 10:59 AM Miguel Ojeda
<miguel.ojeda.sandonis@gmail.com> wrote:
>
> On Thu, Feb 27, 2025 at 6:34 PM Ventura Jack <venturajack85@gmail.com> wrote:
> >
> > I have seen some Rust proponents literally say that there is
> > a specification for Rust, and that it is called rustc/LLVM.
> > Though those specific individuals may not have been the
> > most credible individuals.
>
> These "Some say..." arguments are not really useful, to be honest.

I disagree, I think they are fine to mention, especially
if I add any necessary and relevant caveats.

> > A fear I have is that there may be hidden reliance in
> > multiple different ways on LLVM, as well as on rustc.
> > Maybe even very deeply so. The complexity of Rust's
> > type system and rustc's type system checking makes
> > me more worried about this point. If there are hidden
> > elements, they may turn out to be very difficult to fix,
> > especially if they are discovered to be fundamental.
>
> If you have concrete concerns (apart from the ones you already raised
> so far which are not really applicable), please explain them.
>
> Otherwise, this sounds a bit like an appeal to fear, sorry.

But the concrete concerns I raised are applicable, I am
very sorry, but you are wrong on this point as far as I can tell.

And others also have fears in some related topics. Like the
example I mentioned later in the email.

>>[Omitted] several
>> issues are labeled with "S-fear".
>>
>>      https://github.com/lcnr/solver-woes/issues

Do you have any thoughts on those issues labeled
with "S-fear"?

And the argument makes logical sense. And Ralf Jung
did discuss the issues of osssification and risk of
overfitting.

I am convinced that succeeding in having at least
two major Rust compilers, gccrs being the most
promising second one AFAIK, will be helpful directly, and
also indirectly allay some concerns that some people have.

> > You mention ossifying, but the more popular Rust becomes,
> > the more painful breakage will be, and the less suited
> > Rust will be as a research language.
>
> Rust is not a research language -- I guess you may be including
> features that are not promised to be stable, but that means even C
> would a research language... :)

I have heard others describe Rust as experimental,
and used that as one justification for not adopting
Rust. On the other hand, companies like Amazon
Web Services have lots of employed Rust developers,
AWS more than 300, and Rust is probably among the
20 most used programming languages. Comparable
in usage to Scala AFAIK, if for instance Redmonk's
rankings are used.

Best, VJ.