WIP: Document From implementations in std::sys::unix::process

[LordRatte]

Document From implementations for Stdio, ExitCode

In connection with #51430

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[LordRatte]

Hi, @skade

I am still unsure about ExitCode's implementation. I want to say that it doesn't copy because it uses a u8.

Would that be correct?

[Mark-Simulacrum]

These two implementations are not exposed outside of std, as Stdio here is an internal type (defined in this very module, and not public). This can be a little confusing since there's also a public std::process::Stdio, but that's an unrelated type.

I don't think it's useful to add documentation to these, particularly since these impls are pretty trivial -- we're not doing anything interesting in them.

[Mark-Simulacrum]

I am still unsure about ExitCode's implementation. I want to say that it doesn't copy because it uses a u8.

It looks like that link doesn't really work for me, but presuming you mean this implementation, I don't think that's something we need to add a doc comment to either. It's another internal implementation detail of std, since the ExitCode in question is an internal type. The actual From impl already has a short documentation comment, and there's more detail provided on the std::process::ExitCode type itself.

I'm going to close this PR since I don't think we need to document these two particular From impls. In general, I'm not sure how much value documentation on From impls serves when they are just performing the obvious conversion between the two types, unless we have more detail to offer (e.g., the potential reallocation made in From<Vec<T> for Box<[T]>). I think most of that ground has been covered, and is hard to search for automatically. Thanks for proposing this though!

You can look at some other issues we've tagged as E-easy, which can be good starting points to contributing.