feat: impl core::error::Error for Error

[XAMPPRocky]

Thís will bump the requirement up to 1.81 but this brings a huge improvement to no-std environments.

[KodrAus]

See #851

I would like to do this, but the bump from 1.63.0 to 1.81.0 is a bit too much for us to consider in uuid right now. My rough rule of thumb for what our maximum MSRV can be is whatever's available in the current Ubuntu LTS's package manager, which at the moment looks like 1.75.0.

[paolobarbolini]

I don't have any skin in this, but could the new MSRV-aware resolver help to mitigate the MSRV incompatibility for users using older Rust versions? FWIW, I've noticed that many projects accommodate the Debian MSRV, whereas this is probably the first time I've seen the Rust version of Ubuntu being taken into consideration. This would make sense given Ubuntu's recent interest in Rust. In that case, would the release of Ubuntu 26.04 unblock the MSRV bump in uuid?

[XAMPPRocky]

Ah sorry I missed that. That is understandable, though I would say that I wish this feature in particular could be an exception for the impact it would have for no-std libraries, since I would rather not write my own uuid error type for my libraries or be blocked on crates.io releases.

Hopefully it is only four month wait time until this can be merged.

[KodrAus]

I don't have any skin in this, but could the new MSRV-aware resolver help to mitigate the MSRV incompatibility for users using older Rust versions?

Quite possibly. I'd be interested to see how the rules change with more tools in this area. I have my personal perspective on this, which is that MSRV's are a misfeature and shouldn't exist, but for libraries I try maintain policies that minimize the impact on the widest number of users. I do agree with @XAMPPRocky that std::core::error is a big enough feature that it's worth considering a bump for, like const generics were a few years ago.

[KodrAus]

@XAMPPRocky I've ended up needing to bump our MSRV anyways to upgrade getrandom, so we can now merge this one on too.

[XAMPPRocky]

Fized the merge conflict