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▲ orlp 8 hours ago

We have it: unsafe extern "C" { }.

An actual stable native Rust ABI sounds like a forward compatibility nightmare.

▲Xirdus 8 hours ago | parent [-]

An actual stable native Rust ABI is a prerequisite for distributing libraries as anything other than source code.

▲ChadNauseam 7 hours ago | parent | next [-]

What is the advantage of doing so? Is it for cases where your source code is confidential but you want to sell access to your library?

▲cogman10 6 hours ago | parent | next [-]

Operating systems.

If there's a CVE in tokio, the OS could theoretically publish a patched version of tokio and all apps that depend on that end up using the fixed code.

As it stands now, the OS needs to publish updated versions of all rust apps that depend on tokio.

▲afdbcreid 5 hours ago | parent [-]

That's not how it works basically anywhere except in C/C++ apps on Linux.

▲cogman10 5 hours ago | parent | next [-]

Yes and no.

Yes, in that it's primarily a linux thing as MS has gone the route of saving off basically all dlls for all their OSes for backwards compatibility (though they still backpatch).

No, in that other than Rust and Go (and maybe a few others that emit single binaries, zig?) this is how it works with OS distributed programming language packages. Python, ruby, java, perl, C#, the OS will for all of them control distribute and update the libs independent of the apps that use them.

Also, C/C++ still make up a huge percentage of all apps in pretty much any OS.

▲the8472 2 hours ago | parent | next [-]

> prerequisite for distributing libraries as anything other than source code.

> Python, ruby, java, perl, C#, the OS will for all of them control distribute and update the libs independent of the apps that use them.

Those are all JIT'ed languages, so they're distributed in source or intermediate form, not as fixed-ABI-shared-libraries.

It's really just C where shared libs really work. Even C++ has wrinkles.

▲afdbcreid 4 hours ago | parent | prev [-]

> No, in that other than Rust and Go (and maybe a few others that emit single binaries, zig?) this is how it works with OS distributed programming language packages.

Uhmm... No? E.g.:

- Python has long strongly recommended virtual environments.

- Not to talk about JavaScript which of course manage things per project by default.

- I don't remember what was the state of things in .NET Framework, but in modern .NET NuGet packages are distributed as DLLs with your app.

I don't know other ecosystems well but I believe they aren't different.

▲cogman10 3 hours ago | parent [-]

> Uhmm... No?

Ummm... yes.

How software is maintained by an OS is different from how software is maintained by 3rd party developers.

- Python has long strongly recommended virtual environments.

Yes, if you are developing a private application. But if that application gets adopted by the OS then you can expect all it's dependencies to be sent to a place like `/usr/lib/python3/dist-packages`.

> Not to talk about JavaScript which of course manage things per project by default.

I didn't bring it up because it's one I'm not familiar with. I expect OS maintainers will do similar things with it that they do with python but I'm not 100% on that.

> I don't remember what was the state of things in .NET Framework, but in modern .NET NuGet packages are distributed as DLLs with your app.

And if your .net application ends up installed as an OS package you can expect those dlls to be stored in /usr/lib.

If you are doing C/C++, as a 3rd party app, you aren't putting the .so files or the .dll files in /usr/lib or C:\Windows\System32. You are storing them in the same directory as your application. But if the OS decides to distribute your app, you can expect your .so files to get put into /usr/lib and even System32 (very very rare for MS to do that, but it does happen when, for example, we are talking about drivers).

Edit: Re: node. Here's the debian guidelines for how dependencies ultimately get shredded and distributed. https://wiki.debian.org/Javascript/Nodejs/Manual?pow_referer...

▲afdbcreid 2 hours ago | parent [-]

But that's the thing: almost nobody ships software via the OS today. Even on Linux software is often managed in other ways.

▲cogman10 2 hours ago | parent [-]

Let me rewind this to the top of the thread.

> What is the advantage of doing so?

To which I responded

> Operating systems.

To which you said

> That's not how it works basically anywhere

I think we have reached the point in the thread where you concede that yes, there is somewhere where it's how it works and yes it does apply to languages that aren't C/C++.

So now you're shifting the goalposts and topic to

> almost nobody ships software via the OS today.

That was never something I was trying to debate. The topic was "why would you want ABI stability". And the answer is that if I wanted to rewrite coreutils in rust, then it'd be really useful to have synchronized crates with a stable ABI so I could potentially update those crates independent of the apps that depend on them.

▲afdbcreid an hour ago | parent [-]

I agree that sometimes other languages are packaged this way as well, and maybe I was moving the goalposts. My original meaning was that only for C/C++ (on Linux) the recommended method of distribution is via the OS, while other languages have their own mediums (not requiring stable ABIs). So when they are packaged like that that's mostly because the OS itself or its services need them.

▲gspr 4 hours ago | parent | prev | next [-]

Well yes exactly, because essentially nothing else has a stable ABI.

▲Xirdus 5 hours ago | parent | prev [-]

Because only C/C++ apps have stable ABI. Everyone else would love to do it too but they're S.O.L.

▲afdbcreid 4 hours ago | parent [-]

That's not true. Scripting languages of course need no ABI. Managed languages like C# and Java often keep compatibility of the bytecode. Only AOT languages like Go and Rust cannot.

▲xigoi 4 hours ago | parent | prev | next [-]

Interoperating witt other languages without having to use C as a middleman?

▲Xirdus 3 hours ago | parent [-]

An unstable ABI is entirely sufficient for that, as long as you update both sides in tandem.

▲flykespice an hour ago | parent | prev | next [-]

Yep, and it also imposes a big security risk relying on a closed binary blob that could be injected anytime with a backdoor.

Afaik, odin seems to get it right requiring libraries to be distributed source only.

▲xtajv 4 hours ago | parent | prev [-]

There is another thread complaining about compile times and tmp dir sizes.

Stable ABI dramatically improves the problem space there (without necessarily having anything to do with business model).

▲SkiFire13 7 hours ago | parent | prev | next [-]

It's not a strict prerequisite, you can just require the library being distributed to use extern "C".

▲gspr 7 hours ago | parent | next [-]

Well yes, but then your interface is a C ABI. That's fantastic if the side using my library is any language where C is the only common ground. When the application side is Rust though, it leaves a lot to be desired. It would be delicious to actually interface in a way that respects Rust!

Hell, even if all exposed functions and types would need to be fully monomorphized at the interface, it would be a lot nicer to pass a `&'a [i64]` rather than a `const * int64_t` together with a `size_t n` and have to marshall the slice on both sides.

▲Xirdus 6 hours ago | parent | prev [-]

Or to put it another way, it is a strict prerequisite and Rust already meets it via extern "C".

▲wahern 7 hours ago | parent | prev | next [-]

Another year or three of insane memory and disk prices and people will come around.

A stable Rust ABI would be nice for not just Rust, especially if they refine or extend (formally or de facto) the SysV ABI to optimize passing and returning of discriminants. That could then smooth the way for developing these features in C and C++, such as a primitive error-result type that saw some brief attention in both C and C++ WGs a couple of years ago. Doing it properly--absolute minimum cost, ABI stable, and cross-language--seemed to require too much orchestration across the ecosystem so enthusiasm and ambition seemed to peter out. The work required for a stable Rust ABI could provide the inertia to get that done.

▲afdbcreid 7 hours ago | parent | prev | next [-]

Rust will almost certainly never have a stable ABI by default, and libraries will continue to be compiled from source by default. It might one day have an opt-in stable ABI.

▲fallingbananna 7 hours ago | parent | prev | next [-]

If you can drop the "native" requirement, then Wasm is also a way.

▲redox99 7 hours ago | parent | prev [-]

Why would you want libraries in any other format?

▲eviks 7 hours ago | parent [-]

Not to waste time and space?