Update Result docs to the new guarantees

[Lokathor]

Note: This PR did get merged, even though Github claims it did not.

The Option docs already explain the guarantees given in RFC 3391, so all that we need is a paragraph saying that some Result type combinations will also qualify.

Part of #110503

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[thomcc]

Looks fine except for the unrelated changes.

[the8472]

The option module page currently is the central place for NPO documentation. If Result gets those too then things become more scattered. Maybe the Option page should also link to the Result page.

[Lokathor]

How exactly do you think that would look @the8472 ?

The current wording is intended to be a "one way" lookup. "if X is the case, you can count on Y too", but since the guaranteed effects are part of Option then I'm not sure how Option would refer to Result.

[the8472]

Maybe

Under some conditions the above types T are also null pointer optimized when wrapped in a [Result#Representation]

[dtolnay]

LGTM. Thank you!

[dtolnay]

@bors r+ rollup

[bors]

📌 Commit 9b480da has been approved by dtolnay

It is now in the queue for this repository.

[RalfJung]

Why is this "closed", not "merged"? Something seems to have gone wrong?

(Also the commits would ideally have been squashed before landing this, no need to have all these 1-line-fixup commits perpetually in the git history...)

[Lokathor]

i thought it was handled by bors >.>

[RalfJung]

Normally bors does nothing, Github marks a PR as merged when its commits all landed.

[Lokathor]

https://github.com/rust-lang/rust/blob/master/library/core/src/result.rs#L231-L250

the PR's changes do seem to be in the master branch

[RalfJung]

Yeah, 9b480da got merged. No idea why this is not reflected in the PR state.