[inigyou]

I'll play devil's advocate. I think emitting machine code intended to run is unsafe because you could emit unsafe machine code, which could run. It's the whole system that is either safe or not, not the individual components. If your system gets hacked by a buffer overflow in the end, nobody cares whether it was the linker that overflowed or the code emitted by the linker.

[AlotOfReading]

"Safe" has a very specific definition in Rust. It's not identical to the broader definition used in technical English. You can easily have safe rust code with behaviors any reasonable layperson would call unsafe, like crashing a plane. The original article, comment, and replies were using the word in the Rust sense from my reading, not the English meaning.

[inigyou]

Then that's equivocation. Why do we want a very specific form of safety instead of wanting safety in general?

[steveklabnik]

Memory safety is:

1. Foundational for other forms of safety

2. Has an objective definition, when some other forms of safety are either subjective or inter-subjective.

That said, I don't understand why your parent brought this up to you, you are talking about memory safety in your original comment here, so that's what Rust's safety is about.

[inigyou]

I feel that the buzz phrase "memory safety" has been defined by Rust to mean "the safety Rust gives you". Obviously memory usage can be more safe or less safe, and Rust is decidedly on the safe end of the spectrum, but it also has the gaping type system holes demonstrated in cve-rs which completely shatter any claim that safe code is safe, and there are other bugs which occur in Rust while the programmer is distracted by trying to prove their code is memory-safe.

[steveklabnik]

> the buzz phrase "memory safety" has been defined by Rust to mean "the safety Rust gives you".

It's more that Rust's safety guarantee is memory safety. No more, no less. It's not about buzz, this term was used long before Rust existed.

> it also has the gaping type system holes demonstrated in cve-rs

This is not a "gaping hole". It is a compiler bug, which has never been found in the wild.

> there are other bugs which occur in Rust

This is true! Every language can have bugs in it, and Rust does not claim to solve all bugs.

[inigyou]

Does cve-rs break any type system rules? If so, why hasn't it been fixed yet?

[skissane]

> Why do we want a very specific form of safety instead of wanting safety in general?

Because a “very specific form of safety” is a useful tool in achieving “safety in general”

Because a “very specific form of safety” is tractable for a compiler and language runtime to achieve, “safety in general” isn’t

[nvme0n1p1]

> safety in general

This is impossible. General words like "safe" and "good" are subjective, and useless in a technical context unless you ground the discussion by giving them specific definitions. Otherwise everyone ends up talking past each other.

[inigyou]

Okay, thanks for debunking all good products, safe houses and clean water. I guess they are just products, houses, and water.

[nvme0n1p1]

Good for what? A hammer is good for driving a nail, but not good for driving a screw.

Safe for what? My house is safe for humans, but not safe for tropical birds.

Clean enough for what? Our water is clean enough to wash my ass, but not clean enough to wash a telescope mirror.

Sorry but life is not a Disney movie where some things are unequivocally good/safe and other things are unequivocally bad/unsafe. There are gradients and conditions, and communication requires a shared language between participating parties to navigate them.

[inigyou]

What nail? A hammer is good for driving a nail from the hardware store, but not good for driving a finger nail.

See? I can play stupid word games too.

How tropical are the birds? I'm afraid life isn't a Disney movie where some things are unequivocally tropical/not tropical. How shared is the language? Congratulations on using only two adjectives in your comment besides the ones you're complaining about, but two is greater than zero.

How much your is the house? Do you own it? Without any mortgage or lien?

[nvme0n1p1]

That would mean no language can ever be considered safe, because any language can emit bytes to a file that will later be executed.

[inigyou]

Correct. Safety is a system property, not a language property. Calling a language safe is about as sensible as calling a metal alloy unsinkable.

[BigTTYGothGF]

The only safe program by this measure is the one that's never ran.

[steveklabnik]

> It's the whole system that is either safe or not, not the individual components.

This is a core perspective disagreement. While this is true:

> If your system gets hacked by a buffer overflow in the end, nobody cares whether it was the linker that overflowed or the code emitted by the linker.

That does not mean that increasing the amount of safety in the individual components isn't helpful, because it helps minimize the above outcome, even if it will never be zero.

[gpm]

Safety is a feature of a system - yes. It's also a property of what it's against. A computer could be safe against being hacked but still be dangerously easy to drop on someones toe and break it.

Safety [against something] is also a feature of components - a system made up of only safe components [against a thing] is safe [against the same thing... I'm going to stop this qualification now for brevity]. A system containing unsafe components may or may not be safe but at least you know what components usage you need to look at carefully.

If your linker is safe, linking code will never result in the thing it is safe against. Ever. This is a useful property even if running the linked thing is not safe because it means:

1. When things go wrong in strange ways, you have strict bounds guiding you in figuring out what went wrong.

2. You can build reliable systems that do part of the job, and only have to sandbox the other half of the job. Compiling in a CI system will (if the compiler was entirely safe) be safe. You can do it with secrets present against malicious code. Running tests will have to be sandboxed (assuming running tests isn't safe). This could for instance enable safely sharing significantly more artifacts for incremental builds in CI.

Unfortunately very few compilers are really safe against anything (though I do wonder how I could break my toe on one). Rustc for instance has a giant C++ half called llvm that isn't really hardened at all. We get away with this by just not trusting the compiler when run against potentially malicious code.