Derive more for structs

[Susurrus]

I'd like to propose adding #[derive(Copy, Debug, Eq, PartialEq)] for some of the structs here in libc so they can be used downstream. This may be controversial for various reasons, but I have a specific use case for Eq and Debug on the termios struct. Additionally Clone may be worth adding also, though I don't know if that could blanket apply to all structs.

[alexcrichton]

Debug is covered by #302 and otherwise Eq/PartialEq are left out for compile time implications. The Clone/Copy traits are already implemented for all structs.

I think we'd require an RFC for Eq/PartialEq, so I'm going to close this in favor of #302

[Susurrus]

@alexcrichton Is that an RFC as in the repo rust-lang/rfcs? I'll post on internals as a pre-RFC to get some thoughts together before I try to go down that road. I wanted to ask though, why do you think deriving Eq and PartialEq will require an RFC, is it that big of a change?

[alexcrichton]

Yeah in rust-lang/rfcs.

I personally would be against such behavior as it doesn't make sense for most types and it also has serious compile-time implications. The very few niches which require it would end up imposing a cost on all other users by increasing the compile time of this crate (b/c of so many more impls)

[Susurrus]

What about including it with #302, which I wasn't sure if you meant to suggest that earlier.

[alexcrichton]

Yes having it optional off-by-default is plausible, but I'd still want to measure the impact.