> In the long run, unsafe programming languages will not be used by mainstream developers, but rather reserved for situations where high performance and a low resource footprint are critical.
I see no world where so-called "unsafe" languages would not be used. Most graduates of Computer Science programs can, perhaps with some trouble, implement a half decent C compiler in a weekend or two. This is not a footnote. This fact alone means that for any given piece of hardware you're more likely to find a random C compiler you can use than anything else. Rust, being the most likely contender to replace it, still cannot self-host and the grammar is exponentially more complicated than C. It is more like C + will co-exist peacefully than something like C being replaced (even ignoring the millions of lines of code that already exist). Not for performance reasons but more that you can churn out a C compiler quickly for almost anything given a spec of the hardware.
On topic, I find a desk reference for this is very useful. The CERT C standard is pretty good to thumb through even if you don't adhere to every suggestion.
> Rust, being the most likely contender to replace it, still cannot self-host
What do you mean, "still cannot self-host?"
You say that like it's a critical failure of the Rust project that they need and are attempting to address rather than a trivia item. Rust is perfectly happy relying on LLVM just like (checks notes) half the other languages in existence.
Libraries like LLVM are precisely what the comment you quote is talking about.
I'm not even sure that's true, anyway, with the cranelift backend. Someone can chime in on whether it's good enough for bootstrapping.
Self Hosting your own compiler traditionally was the "end-game" of making a compile-able language. It's a sort of proof of fitness that the language can literally stand on its own.
This article about Zig achieving self-hosted status in 2022[0] points out that they gained many advantages at the cost of a lot of time and effort through this process. Incidentally, they decided to self-host while also supporting LLVM because of deficiencies in LLVM (mainly speed and target limitations). This flexibility includes a separate "C" backend to compile Zig to C in order to target for example game consoles that require a specific C compiler be used.
> You say that like it's a critical goal of the Rust project rather than a trivia item.
In my opinion, you are overly minimizing the potential benefits to Rust and the Rust community for Rust to be self-hosted.
Of course, practically, right now it doesn't matter because most people are more than happy to use the already working system.
As I said, the cranelift backend exists, and it provides many of the same benefits such as improved compilation speed. And it's written in Rust.
But it still feels like a trivia item. C compilers written in C exist, but almost nobody actually uses them. They use GCC, Clang, and MSVC, written in C++. Everybody knows that it's possible to self-host C, so the benefit of actually doing so in practice is minimal.
It's obviously possible to write a Rust compiler in Rust end-to-end. Acting like it's a second tier language because actively doing so not a top focus of the community is gatekeep-y and ridiculous.
> Acting like it's a second tier language because actively doing so not a top focus of the community is gatekeep-y and ridiculous.
Here's where I think you are quite a bit off target, personally.
I certainly was not and I don't believe the GP you originally responded to was saying that "Rust is a second tier language due to [lack of self-hosted compiler]", so hopefully we can set that statement aside and ignore it now.
Let's instead focus on your first statement, which is directly related to what GP and I were arguing:
> It's obviously possible to write a Rust compiler in Rust end-to-end.
It is certainly possible but actually doing so is completely non-obvious because the grammar for Rust is much more complicated than C, and Rust has no formal language specification (let alone an international standard).
While Python does not have an international standard, it does have a formal language specification, which is what allows for things like PyPy to exist.
Meanwhile, to truly understand Rust, one must be an expert in C and learn the `rustc` code base.
It seems like, practically, knowing C and being able to write compilers in C is quite useful if you want to make an impact in Rust or maybe try your hand at making some future Rust replacement (hopefully with a language specification that others can follow).
> It is certainly possible but actually doing so is completely non-obvious because the grammar for Rust is much more complicated than C, and Rust has no formal language specification (let alone an international standard).
The Rust compiler frontend is written in Rust. It doesn't matter how non-trivial writing a Rust frontend is if you can restrict the problem domain to writing a new backend for the existing compiler frontend.
And you can. As it stands there is the LLVM backend that everyone is familiar with, the GCC backend which is nearing completion, and the Cranelift backend which is written in Rust.
Zig is similar. Yes, they are going to replace LLVM by default, but they're not getting rid of their LLVM backend entirely. The main difference between Rust and Zig here is a matter of defaults, where Rust defaults to using LLVM while Zig will default to their self-hosted compiler.
> Meanwhile, to truly understand Rust, one must be an expert in C and learn the `rustc` code base.
Are you under the impression that the "rustc" codebase is written in C/C++? It is not... It uses LLVM, yes, but it's written in Rust.
> I certainly was not and I don't believe the GP you originally responded to was saying that "Rust is a second tier language due to [lack of self-hosted compiler]", so hopefully we can set that statement aside and ignore it now.
The discussion started with the statement that Rust will never replace unsafe languages without the ability to self-host, and then continued with the statement that "Self Hosting your own compiler traditionally was the "end-game" of making a compile-able language. It's a sort of proof of fitness that the language can literally stand on its own."
I don't think that was a completely unfair reading of these statements. The implication is that Rust is "not a fit language" because it "cannot stand on its own" and therefore "will never replace unsafe languages".
> Zig is similar. Yes, they are going to replace LLVM by default, but they're not getting rid of their LLVM backend entirely.
In the article I linked, they did not say they were replacing LLVM by default, but they did say it would become the default for DEBUG builds due to the faster speed of compilation, to be clear.
> > Meanwhile, to truly understand Rust, one must be an expert in C and learn the `rustc` code base.
> Are you under the impression that the "rustc" codebase is written in C/C++? It is not... It uses LLVM, yes, but it's written in Rust.
I am not under that impression, but I can see how my phrasing leads to that conclusion.
After reviewing Rust's Bootstrap on Github[0] I can now more precisely state that one's understanding of low-level Rust will be enhanced by knowing C/C++ (for the LLVM portions) as well as Python (for the Rust does not exist on this system downloading of the stage0 binary Cargo and Rust compilers from somewhere else).
> Cranelift backend which is written in Rust
When this happens, it seems like it'll be possible to get the LLVM bits out of the bootstrap process and lead to a fully self-hosted Rust.
So while you may not personally value that, it seems like some people in the Rust community do.
[0] https://github.com/rust-lang/rust/tree/master/src/bootstrap
What do you mean by "when this happens"? GP's point is that this has already happened: the Cranelift backend is feature-complete from the perspective of the language [0], except for inline assembly and unwinding on panic. It was merged into the upstream compiler in 2020 [1], and a Cranelift-based Rust compiler is perfectly capable of bootstrapping another Rust compiler (with some config changes).