I'm still kind of surprised that Linus ended up allowing Rust into the kernel. Good, but surprising.
Looking forward to this release once it hits NixOS Unstable.
Looking forward to this release once it hits NixOS Unstable.
From what I can tell, he views Rust for Linux as a social project as much as a technical one - attract new (and younger) developers into the kernel, which has become pretty "senior", force all of the "unwritten rules" to be written down, and break down some of the knowledge siloing and fiefdom behavior that has taken place over the years (by sharing it specifically with that younger group of developers).
If you think about it, Rust for Linux is in some ways essentially an auditing committee reviewing all of the API interactions between kernel subsystems and forcing them to be properly defined and documented. Even if the Rust part were to fail (exceedingly unlikely at this point), it's a useful endeavour in those other respects.
But of course, if Rust is successful at encoding all of those rules using the type system, that unlocks a lot of value in the kernel too. Most of the kernel code is in drivers, and it's typically written by less experienced kernel developers while being harder to review by maintainers that don't have background on or access to the hardware. So if you can get drivers written in Rust with APIs that are harder to misuse, that takes a big load off the maintainers.
Note that I'm not saying Rust is easy to learn. I found it to be so, but it's going to be different for everyone. I do firmly believe that it's far easier for the average dev to learn the core of Rust than the core of C++, with far fewer footguns along that path.
https://doc.rust-lang.org/edition-guide/editions/index.html
Rust has a 6 week release cycle and a big complaint is that the language isn’t changing quickly enough so there is pushback from both ends to take into account here. My take is that there are only hard problems still to be solved given that that they need to be solved in a zero cost way.
If Linus's first introduction to C++ was to C++11, I'd imagine his opinion of C++ would be higher (probably not high enough to permit it into the kernel, though). To a large degree, Rust is "take the good new parts of C++11, strip out some of the legacy insanity, and let's also work out how to keep as much of the good stuff in a freestanding environment as possible." Which answers a lot of the objections that Linus had to C++!
We still don't have all of the interesting C++ features in freestanding mode. It's still a fairly unknown component of libc++ and libstdc++. I've only been playing with it recently because I was curious about how many of the c++17 and newer compile time features I could get to work in avr-g++.
And the answer is ... not much.
I've been spoiled by Rust's "core" crate.
That is why contrary to Linus opinion, Symbian, IBM z and IBM i, Windows (since Vista), GenodeOS, and OS X, have C++ running on their kernels even if it isn't the full blown language.
Additionally many of his criticism against C++, applies equally well to Rust, in terms of language complexity, just wait until some kernel driver go crazy with macros or FP inspired designs.
What is indeed a plus for Rust is the secure code mentality that both C and C++ communities have kept downplaying until companies and government had enough with burning money fixing exploits.
Which is funny, because you can see the truth to it. With C++ comes endless debates. No technical reason really, but a social one, and so far the Rust culture seems to be closer to C in that regard.
Still interesting indeed.