Fix: i257 negative zeros

[delaaxe]

Pull Request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
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What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this introduce a breaking change?

• Yes
• No

Other information

[0xLucqs]

I think that for clarity in error messages you shouldn't use the regular Add trait of u256 but rather this and use .expect("useful error message") on the result

[delaaxe]

I think that for clarity in error messages you shouldn't use the regular Add trait of u256 but rather this and use .expect("useful error message") on the result

done, i think you meant those functions

[0xLucqs]

No i was referring to the functions i linked (u256_overflowing_add,u256_overflowing_sub etc)

[delaaxe]

those are clumsier to use, the checked ones allow using expect more directly. unless i completely misunderstood what you wanted to do?

[0xLucqs]

checked_add calls overflowing_add so you get a small improvement. It shouldn't be hard to use just do

let (r, overflow) = u256_overflowing_add(lhs, rhs);
let r = r.expect("....");

[delaaxe]

the first returned value r is a u256, so there's no expect method on it. why reimplement a function that already exists (the checked one I used)?

i also don't want the overflow value

[delaaxe]

@LucasLvy can you check please?

[0xLucqs]

correct leave that as it is

[delaaxe]

Thanks boss