Everything online reminds of when Ubuntu switched to dash for init scripts or something. Good times.
Can’t wait for the whole Rust rewrite of Linux!
Ubuntu continues on it's quixotic mission to kill Linux...
From the company that distributed Amazon spyware (https://www.fsf.org/blogs/rms/ubuntu-spyware-what-to-do) and now turns Debian into Slopian. No thanks.
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I would be very curious about a bit more concrete and substential criticism what is bad (or good) about how the both versions, that goes beyond general arguments like:
Just because it is Rust, it is not safe!
It worked before, don't replace it!
etc.
I had to reimplement and reverse engineer old tech myself as part of my dayjob and had those engineers seen my results it probably would have improved their work as well, since I usually found oddities that they probably did not intend to be that way. This means my work on their work could be seen as another pair of eyeballs, bullet-proofing their original work, instead of seeing me as a threat. That additional pair of eyeballs is crucial to open source software.
This is why it is sad that too much about this whole discussion feels like yet another culture war, heated on the stove of social media figures looking to convert heat into ad revenue.
Which is why I would love to have more concrete points of technical criticism of specific bits maybe even to specific lines in the code or specific reproducable behavior.
If we go the culture-war route nobody wins, if we discuss both solutions on their merits, we all can win.
> since I usually found oddities that they probably did not intend to be that way.
Or it could be you don't have the context like they did. Maybe some hardware bug/quirk that happens on some exotic machine that you don't have.
People still use ubuntu when Debian and Mint exist?
Yes, proprietary hardware support out of the box, and pre-installed option by the few OEMs that sell GNU/Linux computers.
The power of marketing…
Ubuntu does offer some certifications but only for paying customers, so everyone else should really steer clear.
So what is the way forward for Linux to have sandboxi g as strong as Android? Appimage everything? I know it's possible now hacking together things, but I mean by default and integrated.
Maybe we could develop trustworthy free-software applications again, instead of trying to establish a commercial apps ecosystem on top of Linux?
AppImage is not a sandbox
Amutable. Building an immutable and image based system which even the installer can't modify, a-la macOS.
One systemd patch at a time.
Whether you like Rust or not, it's questionable as to why Canonical would push this so much and do it in such a cavalier way.
Will this really make coreutils more secure? I doubt it, if anything there will be a river of new bugs.
So, again, why are they pushing Rust so much? Having Microsoft make Rust a 'Tier-1' language also doesn't bode well.
Canonical has been pushing its own agenda for ages, how many examples do you need?
Microsoft making Rust tier 1 is great, it means probably one day we get a VS proper support instead of VSCode only.
If you head off to Microsoft official blogs, you will find out that Microsoft already has tier 1 support for Java (ironically), Python and Go, besides the usual .NET languages and C++.
Was there something wrong with how they are currently written or do they just want the badge that says they converted to Rust?
Neither. They basically see Rust as the future. They want to be able to attract young contributors and to hire young employees who are excited about Rust and who want the safety features. Bear in mind, the average age of the Linux developer is increasing. They also see technical benefits in Rust. And they are increasing test coverage of both the Rust tools and the tools written in C, IIRC.
My source is this interview with the VP of Engineering at Canonical on this topic: https://corrode.dev/podcast/s05e05-canonical/
Interestingly enough, young developers have no issues writing C or C++ when it comes to game development, Pebble, Arduino or ESP-32 coding.
In reality, I think it much more about taking more control over parts of the ecosystem - the license change is part of it, but also getting rid of the old stubborn communities and maintainers.
Canonical hasn't contributed anything to GNU coreutils in the time since the switch was announced, just to be clear.
License. GNU is copyleft and the new thing is permissive.
We might see a fracture open slowly. For me, even AGPL is not enough
Once they have a more permissive license, cui bono?
Businesses.
There is a reason all FOSS OS alternatives for embedded systems like Zephyr, NuttX, FreeRTOS, IDF, Arduino,... are not GPL based, while Google has purged Android and ChromeOS from it, with the Linux kernel being the only GPL piece left.
Other distros are based of ununtu. Will the all ship with crippled coreutils from now on?
Linux Mint mentioned on their blog that they would be using the Rust versions.
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The project was started long before LLMs existed.
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Ubuntu started out with a slogan claiming "linux for human beings", and it kept that reputation for well over a decade, with a heavy focus on the desktop.
You can split hairs however you want, but this created a legacy, and is why Ubuntu is still one of the top recommended distributions for beginners.
Cool aspirations but I don't think it has significant enterprise deployments compared to RHEL or SLES.
It looks like they have a few paying customers: https://technologychecker.io/technology/ubuntu
And they are slightly behind RHEL: https://commandlinux.com/statistics/linux-server-market-shar...
If you ask their motivation? "We want to make them safer"
They worked pretty fine for decades, now, who needs these rewrites? Not saying it's useless, but in practice, what benefits did this bring?
it's GPL free. which is good for embedded, the business side of it. like cars.
The kernel is still GPL
Good for car manufacturers, not necessarily for cars or their owners. As a car owner I quite like manufacturers to be forced to produce source code.
I was bummed when I came across this: https://github.com/trifectatechfoundation/sudo-rs/issues/129...
I don't understand - I thought sudo-rs was supposed to be a drop-in replacement? If it implements a subset of features how can this be the case?
I don't think sudo-rs ever advertised itself as a drop in replacement. They seem pretty upfront that it isn't their goal. See this list:
https://github.com/trifectatechfoundation/sudo-rs#difference...
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I went upstream and started using Debian instead. Don't listen to the haters: it updates at about the same frequency as Ubuntu LTS.
you are being sarcastic right?
Or just use Arch, and skip the pointless hype squad
Funny .. Arch started growing on me.
Or Pop!_OS that does not vibe slop their distro.
Hmm, this doesn’t make sense. You simply don’t replace utilities with many decades of maturity and that “just work” with something that is not as mature. It will open all users of the distro to all sorts of subtle and not so subtle bugs. I for one don’t want to find myself staring at a mysterious segfault when I want to build the latest version of nodejs or flash a microcontroller. It’s such a pity; I have used Ubuntu for close to 23 years.
on the other hand, Rust is memory safe!
then install the other tool. no one is holding a gun to your head. it isn't windows.
Like how one can easily not use snap on Ubuntu? /s
Fil-C[0] can compile GNU coreutils, it has stronger* memory safety guarantees than rust, none of the compatibility issues that a wholesale rewrite has, and performance that seems to be within about a factor of two[1] compared to the normally compiled code..
[0]: https://fil-c.org/.
[1]: https://bannalia.blogspot.com/2025/11/comparing-run-time-per...
* Guaranteed to crash rather than potentially grant arbitrary code execution.
"Stronger" is absolute bullshit. No data race prevention. No intra-object protection. Mandatory GC, and 5x the compute cost. Nothing like a statically safe language.
It's coreutils, there shouldn't be any threads to be data racing.
Haven't threads been one of the reason some core util got faster?
Only GNU sort uses threads. There is still some room for improvement there, if anyone wants to take a shot at it. :)
Has the code quality in that repo gotten to a good point then? I haven't followed it much, but last I looked[1] (which was a few years ago) almost every tool I looked at in detail had pretty bad performance or correctness issues.
> last I looked[1] (which was a few years ago)
You weren't kidding: it was exactly 4 years ago ("September 13, 2022").
The reason for existence of uutils is ideological, not technical. Thus code quality is of no use for the objective.
I bet you don't know the reason for existence
I’m a huge proponent of Rust and generally lean a lot closer to the RIIR mentality than most, but this effort seems to be such a waste of effort and resources.
There have been a dozen CVEs reported against all of coreutils in the past twenty years. The most recent audit of uutils-coreutils turned up forty-four CVEs.
By all appearances they’re replacing battle-tested and fundamental tooling which hasn’t been a problem with extremely amateurish Rust. The threading highlighted in the linked post above seems pretty egregious.
Same here. Love Rust. Hate rust rewrites.
Can vouch for the sentiment, hence why regardless of the ranting, I am quite supportive of whatever helps to improve C and C++ security story.
Also for Rust based rewrites, they could start by bootstraping Rust compiler itself, dependent on C++ to start it.
They don't do it, because even though LLVM and GCC are written in C++, a pure Rust compiler would not scale to the same level of contributions, and existing capabilities.
The worst thing about rust are the people using it.
My impression is that go developers moved to rust.
I doubt it, as Rust approach to language design is the antithesis of Go's culture.
I would appreciate Go much more otherwise.
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There have been twelve CVEs reported against coreutils in the past twenty years.
There were forty-four against this project in just the last audit.
I am all for RIIR in cases where it makes sense. This does not even remotely appear to be one of them. By all appearances the quality of the code is extremely amateurish at best. coreutils has not been a significant source of vulnerabilities in the past, and they’re replacing it with code written by amateurs that performs worse and already has a worse security track record.
> There were forty-four against this project in just the last audit.
Was there an audit against coreutils? If not, it's not really apple-to-apple comparison.
It doesn’t even matter. The sheer disparity in vulnerabilities over twenty years versus one year is impossible to hand-wave away.
We are talking about fourfold more CVEs over a twentyfold reduction in time.
It really does matter. I don't know enough about this specific case, but multiple order of magnitude differences in CVE numbers are frequently explained by different policies towards finding and assigning CVEs in many many cases.
Absent more information the default should be to hand wave it away as probably such a difference. CVE counts are not a even slightly reliable metric.
Most of them are TOCTOU races or improperly following symbolic links. For example, uutils mkfifo(1) would create a world-readable and writable FIFO before using chmod(2) to restrict its permissions. Another user could replace that file with a symbolic link between the mkfifo(3) call and the chmod(2) to change the permissions of arbitrary files [1].
Other ones I find concerning are that you could also bypass '-- no-preserve-root' with a symbolic link to root [2]. Or by using paths equivalent to "/", e.g., "/../" [3]. Historically, GNU coreutils has been pretty good with symbolic links and avoiding TOCTOU races. The only notable one I can remember is a chmod(1) bug [4].
I agree with your general point that the number of CVEs is a useless metric, though.
[1] https://nvd.nist.gov/vuln/detail/cve-2026-35352 [2] https://nvd.nist.gov/vuln/detail/cve-2026-35349 [3] https://nvd.nist.gov/vuln/detail/cve-2026-35338 [4] https://github.com/coreutils/coreutils/commit/425b8a2f534fe0...
You can use coreutils-from-gnu instead uutils. However since 26.04 build-essential depends on coreutils-from-uutils, it cannot be upgraded while coreutils-from-gnu is installed.
https://bugs.launchpad.net/ubuntu/+source/build-essential/+b...
You can use equivs to create a dummy coreutils-from-uutils package, as mentioned in the responses to that report.
It is frustrating that Canonical has no interest in fixing it, though. It makes it hard to take their claims seriously that you can still use GNU coreutils if you want.
You're specifically frustrated about unbounded stack recursion exhausting the stack, triggered by multiple thousands of directories? It doesn't sound like this is about multi-thousand-deep directory structures, it sounds like it's about something else.
Because even diving into it, I would agree with a prioritisation decision that puts this bug down the bottom of a priority list.
For now you can list dependent packages manually in apt-get install: https://packages.ubuntu.com/resolute/build-essential
But it's clear that Ubuntu will remove coreutils, genuine sudo and other tools from the future versions. It's the direction, it's ideological and thus nor merit nor our feedback will change anything here.
> genuine sudo
That made me curious, it sounds related to this:
Ubuntu 26.04 Ends 46 Years of Silent sudo Passwords - 5 months ago (413 comments)
nah
i was referring to their counterfeit sudo emulator written in rust. It's called "sudo-rs" afair.
Ah I see, found it.
Security issues discovered in sudo-rs - https://lists.debian.org/debian-security-announce/2025/msg00...
Sudo-Rs Affected by Multiple Security Vulnerabilities - https://www.phoronix.com/news/sudo-rs-security-ubuntu-25.10
Sudo-rs enables password feedback by default - https://www.phoronix.com/news/sudo-rs-password-feedback
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The account you’re replying to has 8 karma across 13 comments in the last 11 years.
The other comments are about as good as the one you replied to.
> Ubuntu devs has been nothing good FOSS
Did you mean nothing "but" good?
"nothing good" is more accurate
Yes, sorry and thanx, I played a bit with the sentence, not happy with the first thing I submitted -> Corrected now.
Legacy is a bit harsh...
FWIW, Canonical did not reach out to any of us who maintain GNU coreutils before, after, or during the transition. Had we known, we could have easily warned them about the incompatibilities.
Yeah, shouldn't have called it legacy, perhaps OG would have been more appropriate.
> Ubuntu devs have been nothing but good FOSS citizens
They have forced systemd despite feedback and genuine concerns.
They have forced fake sudo and uutils the same way.
So, ideology over merit. That doesn't mean that all of the Ubuntu devs are this way, but this means that the company is consistent in its ways to hurt Linux.
“Hurd Linux”? Maybe leave that judgement to Torvalds.
Canonical is a company they do what the CEO wants. And you are free to do what you want.
Quick question: are the fruits of your labor mostly given away for free?
Probably true, but the direction Linux is going these days is concerning
It's important to remember that this is a story about Ubuntu, and not Linux, and they are two very different projects with different motivations.
It does not matter. Both (Ubuntu [0], and the Linux Kernel [1]) use, build with and in some cases promote using LLMs.
[0] https://discourse.ubuntu.com/t/the-future-of-ai-in-ubuntu/81...
True, and that's a bummer, but it's the decision of the maintainers of those projects to make.
If it goes really sideways, and it may, you can either fork Linux or move away to something like one of the BSDs.
Care to elaborate?
“Concerning” is just a right wing thing to say. They get the habit from Musk. They say it and don’t elaborate, so it kinda operates like a dog whistle.
Great "elaboration" (actually it's an "example"), indeed pulling everything into the political dimension is one of the concerning things regarding anything Linux nowadays, imho. Next up: DHH!
1) Corporate forced slop acceptance by e.g. Linus and Debian.
2) Seeing how bad the Linux kernel is with all the AI CVEs. It will get worse.
BSD is the future.
Netcraft may confirm that some day
BSD is the future. Wishful thinking. Nothing bad about it, but chances are low.
Ss for AI slop. There is lots, but I do not think Linus will tolerate a heavy quality degradation and policies will be set up to strike a good balance.
You were down voted, odd. But this I fully agree with, the latest thing for me is Wayland being forced upon us.
X11 and everything around it is unfixable security hazard slop, just slop that was painstakingly created by humans.
Also Wayland is it being forced on us? I have plenty of coworkers that run X daily because they are still afraid of the Wayland boogeyman despite the fact that their supposed clipboard and screen sharing problems in Wayland (the only two supposed problems they can name) have been solved for years.
GPL -> MIT
Does this actually matter that much for some tools when the kernel is GPL?
I does. The OP says "Linux" but means "Linux distros", which are made of thousands of "commingled" pieces (i.e. the licence of one piece does not affect the other).
Each piece that becomes MIT means less pressure on corporate users to give back any changes they make, and we'll end back up in the 1980s again where "Amazon Linux" is full of secret-sauce they refuse to publish and makes the base system incompatible with "Google Linux" (or whatever happens to be kicking about), creating deliberate lock-in out of a system that started open. In much the same way that macOS and FreeBSD are divergent today.
In theory there could be a the MIT version relicensed to GPL and this version could be carried as a standard if having MIT software as core utilities was considered enough of a threat - right? You just have to retain original license/attribution.
That would be an awfully awkward move in the realm of Linux-related politics but if having an MIT-licensed coreutils was such an existential thread, at least you can fix it with aggressive license moves and not code.
That doesn't matter. Amazon or whoever can add as much secret sauce as they like; people can freely use the original so there's no issue.
We've balkanized Linux but you're free to use the original (which we are deliberately incompatible with, as is rival #2, rival #3, rival #4, etc. and we're all mutually incompatible with each other)
Amazon and other clouds already patch the hell out of Linux, but they don't distribute physical devices with that Linux on it to anyone, so they don't have to deliver source code either.
I am not totally sure I see the actual concern here, that a company is going to sell devices with a really great `find` implementation but not contribute it upstream?
In the 1980s and 1990s, there were a number of commercial Unices (SunOS, HP-UX, AIX, IRIX, etc.) Every one of them was incompatible with each other, sometimes subtly, sometimes blatantly. They were all competing against each other and all seemed to encourage you to use their proprietary extensions in your software and deliberately fuck over anyone using any other variants.
What it meant was a headache for writing platform-agnostic software. It was not a productive way to create software.
Replacing GPL software with MIT software just encourages this behaviour to come back. We already see it with how macOS userland took FreeBSD and sprinkled incompatibilities everywhere.
I really don't understand why Canonical rushes this. If 'rm' can't remove all possible directory entries, that is a big issue:
$ podman run --rm -it ubuntu:26.10
$ apt update -y; apt upgrade -y
$ rm --version
rm (uutils coreutils) 0.10.0
$ gnumkdir -p $(yes a/ | head -n $((32 * 1024)) | tr -d '\n')
$ rm -rf a
Segmentation fault (core dumped) rm -rf a
$ ls a
a
$ gnurm -rf a
$ ls a
ls: cannot access 'a': No such file or directorybut it segfaulted in a memory safe way.
And that’s why i keep ubuntu far from my computers…
I mean, that should work... but you can see why that would be considered low priority right?
to enable GPL free embedded Ubuntu, field tested on all platforms (because it happens to be the default).
Wow! Memory safety and such... Reminds me when a friend of mine wrote in IRC long time ago: "Hmm, tail just segfaulted." When I asked "Are you on Hurd?" he just replied "Yes."
Hi, this is not a one bug.when the change app flags not working or not happening. I was measured with bsd and busybox.
Rush? This is an interim release (95% or so only tracks LTS's) that is not even out yet... Go file a bug reports if you have some time.
My experience is that filing bug reports to ubuntu is a complete waste of time. Not sure if it's different for paying users.
I have. It has been an open bug upstream for years as well.
ok, that's concerning, if you post it here I'll vote for it (after confirming).
The bug report I filed several months ago hasn't been looked at. Many of these utilities were released and made the default for Ubuntu 26.04 LTS!
There's a whole load of basic bugs reported and ignored:
They eventually fixed the one where it didn't sort properly, but it tooks months: https://github.com/uutils/coreutils/issues/12253 https://github.com/uutils/coreutils/issues/12912
Reporting bugs before Ubuntu releases has never worked for me. They always land a bunch of major changes after the supposed "freeze" then they ignore all feedback because of the freeze. It's infuriating.
Glad to hear that I am not alone. I feel like launchpad is totally ignored most of the time.
To get a response on a buggy GNU coreutils patch of theirs [1], I had to mention it in a rust-coreutils bug months later...
[1] https://bugs.launchpad.net/ubuntu/+source/coreutils/+bug/215...
I've been a Ubuntu user for about 20 years, and I file bugs every now and then on launchpad. I don't recall any of them ever being fixed.
Maybe the bugs get traction if you have a service contract?
Best to file bugs directly to upstream, but that of course means you should try it on the latest upstream version and not whatever version ubuntu ships, so it's more friction.
I did, and the original dev of the component fixed it within a few days. It was straightforward, a backwards reading of a spec, reordered.
The fix is still sitting unmerged many months later.
This surprised me since I thought the project was in heavy bugfix/compat mode. I won’t touch it until I see some velocity on open bugs.
Fork Ubuntu and threaten their business model, that’ll get their attention.
Only half joking.
There's very little incentive to switch. When people release for Linux they almost always first/only test it works on Ubuntu - hence it's going to be the least buggy. (ex: GOG only seemingly tested games on Ubuntu)
So the switching cost is buggy software. You'd need something radically different that brings enough new features to the table to make it worth it the switch and dealing with bad/non-existant support.
I think something like Nix/Guix but with stable library versions that matches Ubuntu/Debian LTS ones 1-to-1 could get traction
There are plenty of Ubuntu forks?
Ubuntu is the fork; just use Debian.
Let them first fix Snap.
There is no reason for anyone on any distro to use snap.
It will die so just leave it alone.
They need to kill snap ...
Yes, please. Linux distros is better with macos approach. And making appimage first class makes a lot of sense.
AppImages do not work anywhere close to how macOSs .apps do, and even if they did the approach isn't correct for how things work on Linux.
I'll avoid it at this point anyway. The Rust coreutils is another reason for that. Snap, monetizing updates, telemetry, enough is enough.
Yup. After almost 20 years, I have had enough of their crap. All of my new machines are getting Debian. Can’t wait until I am free of Ubuntu.
Appimages are bloated and unreliable. You can't guarantee that your app will run on any machine because it might depend on different system libraries.
Flatpak uses shared stable runtimes that are the same everywhere and don't take up space more than once. It also comes with a native update system and sandboxing. Snap is the same thing but worse.
My problem with flatpak is that the underlying runtime has a limited lifespan. I used the Sublime Text 3 flatpak for many years, and it was deprecated a few months ago because the runtime it was using was no longer supported. This caused people to update the flatpak to Sublime 4, which is good, but I only have a license for 3. In the end I just downloaded the binary for 3 from their website, and it still just worked. Flatpak still doesn't save you from bitrot.
> Snap is the same thing but worse
IIRC Snap relies heavily on AppArmor for sandboxing, so on anything non-Ubuntu the sandboxing is non-existent.
I think ubuntu wants to kill desktop linux. No other explaination of why they push firefox inside snap, which then proceeds to constantly crash, when firefox used normally works completely fine.
I haven't tried chromium but I presume it's the same issue.
At work I'm forced to use ubuntu and I placed snapd on hold and added mozilla's own apt repository to my configuration to get firefox.
At least in the past few months the dbus crashes (been using systemd on debian for several years just fine, this never happened) that render the system unusable and un-rebootable have stopped… I guess when my company will decide to upgrade to 26.04 there will be more instability and problems.
sandboxing a browser makes total sense. my firefox and chromium running as snaps never crashed a single time for as long as I can remember, and I use both every day, at the same time.
Firefox installed as a snap feels sluggish to me. When I install a Ubuntu system, the first thing I do is to uninstall any snap and install the apt versions of things, possibly adding official PPAs or using Guix to install software.
why bother with ubuntu at all ? If you want ubuntu but without snap out of the box, Zorin is 1 option. Or if you also hate gnome, linux mint.
yeah, this is a bug. And yes, it should be fixed. But I don't think it will affect many users, I mean who has a 32000 -evels deep directory on their system?
It's less about the specific issue and more indicative of bad/insufficient test coverage
That way of thinking just means it'll never be fixed
Nah, people should (and do) fix small issues as well as big issues. Lying about the scale of issues and calling them "big" when they aren't just leads to no ability to prioritize or evaluate.
Incidentally someone submitted a PR for this issue about 3 hours before the first comment about it in this thread - https://github.com/uutils/coreutils/pull/14554 (and 2 hours before this link was submitted to HN)
"The Linux philosophy is 'Laugh in the face of danger'. Oops. Wrong One. 'Do it yourself'. Yes, that's it." Linus Torvalds
The problem there is that this is exactly the class of bug that does not exist in GNU coreutils because of philosophy of that project. Non-existence of such bugs proves that the impementation is not copied from AT&T code.
It's complicated to do it yourself when upstream won't accept your code.
What approach would you suggest for priorisation of tickets?
Capitalism.
Ideally there should have been no tickets at all if all that's happening is a program being ported to another language.
This isn't a port - it's a re-implementation without any use of the original source.
That's also not all that's happening. It's also making improvements like better internalization support, better error messages, and a small handful of other extensions.
I have had to tell them repeatedly to stop copying tests verbatim, including the original comments from GNU coreutils. So I doubt this is true, which is frustrating.
What's wrong with them using the coreutils tests?
What programmer or programming language can't iterate a loop more than 32000 times?!
Rust ? Because of ... memory safety. /s
When triaging an issue you have to prioritise. Do you fix a problem that affects 2-3 people or one that may affect thousands?
By that logic, why even spend effort migrating from a known-working implementation to one which is known to have outstanding bugs that there isn't enough bandwidth to fix?
The point is that such bugs shouldn't exist in the first place.
Using recursion on unbounded inputs on a programming language that doesn't support that (which are most) is an extremely classical mistake that really should be known to all programmers, especially those of low level languages that care about safety.
Every time you call something recursively you should be thinking "how deep is this?".
It's a stack overflow which means it's using recursion and for historical reasons that don't make sense any more, stacks are teeny tiny on 64-bit Linux - apparently only 8 MB on Linux! I'm not sure why they don't raise it to something reasonable like 4 GB. I guess because they want consistency with 32-bit? Maybe we can finally change it if/when they phase out support for 32-bit Linux. Apparently it might not be that far away:
8MB is the default per-thread stack size from glibc, also seems to be the default "ulimit" from pam or the kernel, I'm not sure. So for the main/default thread (or if not using threads) the process can use setrlimit() and for threads it can use pthread_attr_setstacksize() to get bigger stacks if it knows it may need them.
8MB is pretty huge though; musl libc is famous for defaulting to much smaller per-thread stack size of 128KB (to avoid over-committing lots of memory when there are many threads - the main dev is really principled/opinionated on this topic, but again there are a few ways for applications to explicitly size their stacks as large as they need). Linux kernel threads get a bit less than 16KB!
OIC. Rust doesn't guarantee optimizing tail recursion. How unfortunate for a language that's getting widespread adoption.
I don't think that's related? The bug alluded to looks something like
function rm(node) {
for (const child of ls(node))
rm(child);
unlink(node);
}
Do any widely used languages guarantee tail call optimization? It's a pretty niche feature.
Scala, ocaml, racket, clojure, zig.
For recursion only kotlin.
(For most of these only with syntax specifying it)
For what it's worth there's reasonably active [1] work on implementing opt-in guaranteed tail calls - but it's not particularly fast going. LLVM (the backend rust uses) needs better support for musttail (e.g. some architectures just don't support it [2]).
[1] https://github.com/rust-lang/rust/issues/112788
[2] https://github.com/rust-lang/rust/issues/153827
By-default guaranteed tail calls really isn't rust's style, because it means subtle changes (introducing a destructor, re-ordering code, etc) can change semantics without you realizing it. If you want to guarantee that a call can't allocate a new stack frame you should have to say it.
> because it means subtle changes (introducing a destructor, re-ordering code, etc) can change semantics without you realizing it.
No, it won't change semantics - if you say @musttail or similar, it will simply fail to compile if you, say, introduce a destructor - the semantics will not subtly change.
Incorrect. `become` does change drop order - https://play.rust-lang.org/?version=nightly&mode=debug&editi....
That's not implementing tail calls breaks things, that's bad design of implementing tail calls breaking things.
The whole idea of "let's change semantics to make it easier" is dumb.
If you want guaranteed tail calls, change your code until it works.
Uh, yes, if you guarantee the semantics only when the code explicitly opts in and not by default then semantics will not subtly change, that is the point of my comment
It's not a change in semantics of compiled code. It is only a change of whether or not the code will compile.
Not so familiar with this area, but isn't the existing behavior of implicitly creating new stacks more of a problem than implicit tail-call elimination? Seems the latter is a kind of compiler-level optimization, of which there are already many (I think) that change the semantics internally but guarantee the outward behavior stays the same.
But I can understand the preference for an explicit opt-in, to make clear that it is enforced and not assumed.
> implicitly creating new stacks
I'd argue that it's explicit - that's what a function call does and you don't have implicit function calls in rust.
> Seems the latter is a kind of compiler-level optimization, of which there are already many (I think) that change the semantics internally but guarantee the outward behavior stays the same.
What you're asking for here already exists. Tail calls might be optimized into not allocating extra stack frames, the rust compiler just doesn't guarantee that it will perform that optimization (and almost certainly won't when code is compiled without optimizations... for instance).
What people want is the semantic guarantee that the stack frame won't be allocated. Not just a compiler that often performs the optimization. Otherwise you can't be sure that your code will keep working with new compiler flags/versions/architectures/... You could say "whenever the code is the right shape we'll guarantee the optimization" (C++ famously did this for things like copy elision)... but now the shape of code comes with non-obvious semantic guarantees and that's not rust's style. Hence the proposal for a keyword instead.
I see it, certain algorithms need guaranteed tail-call elimination, otherwise they are too inefficient and must be manually unrolled or rewritten to avoid blowing the stack. So a compiler optimization that is "nice to have" is not good enough.
No algorithm requires tail-call elimination in a general-purpose language with imperative mutability. It's just another way to express iteration.