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Comment by sophacles | Hacker News Reader

I'd like to see a `#[no_panic]` tag similar to the `#[no_std]` one.

Yep, exactly something like this!

Implementation is the challenging part: the standard library and community ecosystem is full of legitimate uses of panic, and there are instances where panics might appear in the source code of dependencies but not in (optimized) builds.

> full of legitimate uses of panic

Yes, but the whole point of `no_panic` is that in this context there are no legitimate uses of panic. If that means making a bunch of parallel APIs that return results for this super-correct code then so be it.

You're absolutely right. I meant primarily in terms of the challenge of writing panic-free code while still being a consumer of the crate ecosystem.

surely it should be #[DONT_PANIC] in large friendly letters.

Hah, nice one. I think we could get the unicode folks to accept an emoji form of this: https://thebullelephant.com/wp-content/uploads/2016/12/dontp... and alternately accept `#[$UNICODE_FOR_SAID_EMOJI]`.

Rust doesn’t allow emoji in identifiers, following the UAX #31 rules. It would require a significant break in someone’s tradition to get such a thing through. … quite apart from the implausibility of getting such a character into Unicode in the first place.

Or implied by the #[keep_calm] attribute

That, or a subset of Rust that has all the panicking functions removed and only has std API that works with Result and Option.

Presumably using `#[no_panic]` would require `#[no_std]`? Would you be allowed to use unchecked arithmetic, which panics in dev builds but not release builds?

Why would #[no_panic] require #[no_std]? There are perfectly legitimate reasons for not wanting panicking in code that uses std, and it’s possible to panic without std.

How to you expect it to work?

Could you not enforce that functions tagged can only call other functions with the tag and must not call panic?

This would not protect against stack overflow or similar environmental panics.

That's the issue. Rust panics on division-by-zero, Rust panics on out-of-bounds, Rust panics on signed integer overflow in debug mode. Stack overflow can happen on every function call which is also panic. Too many implicit panic sources.

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