Re: The Case for Rust (in the base system)

On Tue, 23 Jan 2024 09:41:01 +0000
David Chisnall <theraven@FreeBSD.org> wrote:

> On 22 Jan 2024, at 22:45, Robert R. Russell <robert@rrbrussell.com>
> wrote:
> > 
> > Having had the luxury or curse of not being stuck with only one
> > programming language I have learned usable pieces of several. C++ is
> > not on that list even though I have the most formal education in it.
> > My best way of answering why is this. Would you write or use a C++
> > codebase maintained by the average developer with just Vi? Up to
> > C++03 I can say yes, after that the answer is no.  
> 
> I have no idea what this means.  There’s absolutely nothing in newer
> C++ that makes it harder to write with a text editor.  There is a lot
> that makes it easier to write correctly.
>
> For reference LLVM is about 4MLoC (and about 5M lines of comments,
> something that FreeBSD could definitely learn from) and is written in
> modern C++.  I don’t think I’ve ever used an editor other than vim to
> work on it.  I don’t use nvi, because it’s not the ‘80s anymore.
> 
> I use ALE with vim, which integrates with clangd via LSP and provides
> autocompletion and error reporting for anything that can generate a
> compile_commands.json.  That’s not specific to C++.  I wouldn’t want
> to write C without syntax highlighting, autocompletion, or live error
> checking either.  It’s possible to do so for C or C++, but you’ll be
> less productive.
>
> > A consequence of Microsoft's "Welcome back to C++" item that may
> > have gotten missed is what resources are they spending to enforce
> > compliance with a certain C++ standard?  
> 
> I have no idea what this means.  ‘Compliance with a certain C++
> standard’ is a thing that your compiler tells you when you try to
> compile.  
> 
> > Particularly, to enforce the restrictions on anti-patterns?  
> 
> That varies from project to project.  I generally use clang-tidy and
> clang-format in pre-merge hooks in CI for the projects that I worked
> on at MS and that I work on personally.  And, of course, code review.
> Automated tooling is no substitute for code review.  
>
> > Cargo needs approximately a dozen lines in a
> > configuration file to restrict its upstream sources. That includes
> > whitespace and formatting.  
> 
> 
> Here is the script that runs formatting and static analysis across a
> codebase that I maintain:
> 
> https://github.com/microsoft/cheriot-rtos/blob/main/scripts/run_clang_tidy_format.sh
> 
> Almost all of the complexity is in *not* running it on files that we
> have imported from elsewhere or where, for compliance with external
> standards, we don’t want to enforce our naming rules, and for finding
> the relevant toolchain files.  The actual checker bit is right at the
> end.
> 
> Most projects run this kind of check through their build system, but
> we wanted to run it on headers in isolation as well as on full
> compilation units.  
> 
> David
> 

The specific anti-patterns is was thinking of in both instances is
called Meta Template Programming. Back in C++03 I just used the
template system as a form of generics. In that role it works well and
with the new smart pointers definitely improves some of the older
problems C++ had.

However, C++ definitely has a complexity cult and a ricer cult in its
community. The overlap between the two appears to be fairly large which
worries me.

I have less reservations about C++ than I did earlier, though I think
the build system may require major surgery to support it well.