Python cryptography, Rust, and Gentoo [LWN.net]

Python cryptography, Rust, and Gentoo

Posted Feb 12, 2021 21:55 UTC (Fri) by ceplm (subscriber, #41334)
In reply to: Python cryptography, Rust, and Gentoo by roc
Parent article: Python cryptography, Rust, and Gentoo

> Rust is incredibly good at avoiding compatibility breaks in practice.

Just an anecdotal piece of my personal experience. The only piece of Rust software I was following (for a year or so) was https://github.com/daa84/neovim-gtk/ and it forced me to upgrade my Rust compiler twice, because code for the later versions were no longer compatible with the old one.

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Python cryptography, Rust, and Gentoo

Posted Feb 12, 2021 22:29 UTC (Fri) by roc (subscriber, #30627) [Link] (8 responses)

That is a completely different issue.

The original commenter said:
> [Rust] adds backward compatibility breaks. It isn’t as bad as Python at this, but then the Python people are not advocating Python as a systems language. C’s one great strength is that C code is C code. It tends to just keep working over time.

Likewise, Rust code tends to keep working over time: new versions of the compiler can compile old Rust code. That's what we were talking about.

You are talking about a different issue: can old versions of the compiler compile new Rust code? No, not always, because Rust adds features and some Rust projects like to use those new features.

If you're developing software and you want to never upgrade your compiler, that's fine. Just don't, and stick with the set of features it supports.

If you're consuming someone else's software and never want to upgrade your compiler, better pick projects with the above policy.

Python cryptography, Rust, and Gentoo

Posted Feb 13, 2021 18:51 UTC (Sat) by ceplm (subscriber, #41334) [Link] (7 responses)

Of course, technically, you are completely correct, but I don’t have these problems (or at least not that frequently) with programs in most other programming languages (not mentioning C, because that’s really unfair). Either Rust is still too unstable, or older versions were so lacking that programmers are forced to use the latest features from the bleeding-edge compilers. Am I right?

Python cryptography, Rust, and Gentoo

Posted Feb 13, 2021 22:59 UTC (Sat) by mathstuf (subscriber, #69389) [Link]

Forced to use the latest features? Not likely. Allowed them to remove bad patterns, simplify others, or just use new ones? Sure. There's the nightly-only `-Z minimal-versions` flag to use the *minimum* declared versions of dependencies, but discussions about stabilizing it and making it work across the ecosystem haven't gotten very far (and I've submitted over a dozen PRs to make my dependencies work with the flag).

Python cryptography, Rust, and Gentoo

Posted Feb 15, 2021 1:21 UTC (Mon) by roc (subscriber, #30627) [Link]

I don't know why the neovim-gtk authors bumped their MSRV but most likely they saw some small feature that would be useful, and view upgrading the compiler as a trivial step (`rustup upgrade`), and so saw it as an easy win. If upgrading the Rust compiler is actually hard for some significant part of their community (I don't know why that would be), let them know!

Python cryptography, Rust, and Gentoo

Posted Feb 15, 2021 10:25 UTC (Mon) by laarmen (subscriber, #63948) [Link] (4 responses)

I think it has to do with the fact that Rust has really good tooling to manage the toolchain from a developer PoV along with a good backward compatibility. Upgrading the rustc version is assumed to be a trivial step (rustup update and voilà), and if you're an application author you can provide binaries for most platforms, which means the upgrade doesn't concern those users as there is no need for them to upgrade their runtime.

In contrast, most other languages either have a runtime component, which makes upgrading painful for all users, and/or an upgrade process that was not trivial when the community around the language started forming its habits. I would assume you'll find a similar attitude in the Go ecosystem.

Python cryptography, Rust, and Gentoo

Posted Feb 15, 2021 12:03 UTC (Mon) by ceplm (subscriber, #41334) [Link] (3 responses)

That’s what I call immature environment: if it works on my laptop, it’s perfect, ship it!

Without considering maintenance costs, long-time support, and or combining multiple Rust projects in one system (e.g., Linux/Mac OS X distributions).

Python cryptography, Rust, and Gentoo

Posted Feb 15, 2021 13:47 UTC (Mon) by laarmen (subscriber, #63948) [Link] (1 responses)

You're putting words in my mouth.

The fact that application developer using Rust don't particularly care about sticking to a lower version of Rust is indeed partly because the language is still evolving and gaining features, for instance async/await which was not available in the version of rustc originally shipped with Debian (the situation has since changed). But my point is that it also comes from the fact that it is *very* easy for a Rust developer using what is considered the standard way of developing in Rust to install and use multiple versions of a toolchain, and for most users *from their PoV* the version of Rust doesn't matter since either they compile from source and can thus be expected to use standard (for Rust) tooling, or they are using already-compiled binaries with no runtime dependency on the version of Rust.

Saying that maintenance costs, long-time support and combining multiple Rust projects in one system isn't considered by the Rust community is just plainly false. It's just a matter of perspective : they consider that rustc is just another build-time dependency and it's okay to require those that build to bump it, which in its face makes sense : you're already updating something in your system (the project itself), it shouldn't be a big bother to update something else.

I'm not saying this is the absolute right choice, as there clearly is a mismatch with how distros work, but things are not black and white.

Python cryptography, Rust, and Gentoo

Posted Feb 15, 2021 14:32 UTC (Mon) by ceplm (subscriber, #41334) [Link]

> You're putting words in my mouth.

I am not. I haven’t mean it as pretending to quote you, or I haven’t even claimed that you would support this statement, but that it seems to me that this attitude is too present in the Rust community.

> […] the language is still evolving and gaining features, for instance async/await which was not available in the version of rustc originally shipped with Debian (the situation has since changed).

Yes, in other words, the language is still too immature for the projects of the size of Linux distros and similar.

Python cryptography, Rust, and Gentoo

Posted Feb 15, 2021 15:28 UTC (Mon) by Cyberax (✭ supporter ✭, #52523) [Link]

> and or combining multiple Rust projects in one system (e.g., Linux/Mac OS X distributions).
It works just fine with multiple Rust projects and environments (see https://doc.rust-lang.org/edition-guide/rust-2018/rustup-... ). I have several Rust versions installed on my laptop side-by-side for tests and cross-compilation.

And the fact that you mention Windows/macOS is especially funny, because Rustup has native installers for them, making experimenting with them very easy.

And of course, Cargo makes sure that libraries don't interfere with each other, so each project gets its own dependency closure.