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From: Neal Gompa <neal@gompa.dev>
Date: Wed, 10 Jan 2024 11:25:29 -0500
Message-ID: <CAEg-Je_P6-3PWNxM4HCzcgM=H4Y1vmywaM3gbwK0gAe0UVoZGw@mail.gmail.com>
Subject: Re: [PATCH 00/45] C++: Convert the kernel to C++
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: jirislaby@kernel.org, dhowells@redhat.com, hpa@zytor.com, 
	linux-kernel@vger.kernel.org, pinskia@gmail.com, kent.overstreet@linux.dev
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On Wed, Jan 10, 2024 at 10:52=E2=80=AFAM Jason Gunthorpe <jgg@nvidia.com> w=
rote:
>
> On Wed, Jan 10, 2024 at 08:04:53AM -0500, Neal Gompa wrote:
> > Hey all,
> >
> > I would like to speak in support of this too. It is not uncommon
> > to see operating systems code written in C++ (notable examples are
> > Haiku OS, Serenity OS, and Zircon/Fuschia) and I do feel that there
> > are benefits to C++ for Linux code. Modern C++ (such as C++14 and
> > newer), offers a lot of nice base language features that can make
> > some of the kind of stuff that Linux does easier (as H. Peter Anvin
> > has detailed in his post[1]).
>
> Me too. If we are serious considering Rust I think C++20 deserves a
> fair shake as well. Especially since I heard the C++ working group is
> apparently looking at future C++ extensions for Rust-esque memory
> safety these days.
>
> I personally think the kernel community would have an easier and more
> incremental time swallowing C++ than it would Rust, and C++17 is
> already mature with fully working stable compilers. In particular I
> feel someone familiar with C would have a easier ramp up to some
> imagined "kernel C++20 subset" than to Rust.
>
> Further, I feell that having a single base line of "all code compiles
> in a C++20 compiler" and localized variations of what idiomatic style
> and features different parts use would be ultimately more maintainable
> than intermixing C and Rust togther.
>
> I've also got a fair bit of experience with C++17 and I would add to
> HPA's note that the modern idiomatic usage of C++17 is *way* different
> than older versions. If someone was traumatized by early 2000's or
> 1990's C++ then it is not entirely fair to carry that to modern
> C++17. Especially when combined with a modern environment with
> something like clangd to help grok the code. (Though SFINAE is still
> an inscrutable terror)
>


For what it's worth, I'm totally in favor of C++20 as well. I've
mostly written C++17 as of late and it is really nice to me, but I'm
genuinely excited about C++20 and newer revisions.

I also think that Linux adopting C++ and intentionally adopting safety
features that exist and are being added to C++ over time would also
further encourage the ecosystem to use them as well as make the Linux
codebase much easier to work with.


--=20
=E7=9C=9F=E5=AE=9F=E3=81=AF=E3=81=84=E3=81=A4=E3=82=82=E4=B8=80=E3=81=A4=EF=
=BC=81/ Always, there's only one truth!