Add Option::is_none_or

[OliveIsAWord]

This is my first contribution to Rust, so I welcome any churn no matter how pedantic. :)

This was discussed on this tracking issue.

[rustbot]

Hey! It looks like you've submitted a new PR for the library teams!

If this PR contains changes to any rust-lang/rust public library APIs then please comment with @rustbot label +T-libs-api -T-libs to tag it appropriately. If this PR contains changes to any unstable APIs please edit the PR description to add a link to the relevant API Change Proposal or create one if you haven't already. If you're unsure where your change falls no worries, just leave it as is and the reviewer will take a look and make a decision to forward on if necessary.

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• Stabilizing library features
• Introducing insta-stable changes such as new implementations of existing stable traits on existing stable types
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• Changing observable runtime behavior of library APIs

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @thomcc (or someone else) soon.

Please see the contribution instructions for more information.

[thomcc]

Hi, this is a new unstable API, so you need to file an ACP for this. See the bots message for the process. Thanks.

[thomcc]

Suggested change

	#[unstable(feature = "is_some_with", issue = "93050")]
	#[unstable(feature = "option_is_none_or", issue = "none")]

For now. But you can wait for the ACP to be resolved.

[OliveIsAWord]

r? @m-ou-se

[thomcc]

Ah, I didn't see the message about the tracking issue (or perhaps you edited it). I guess this possibly can skip ACP? No strong feelings from me either way.

[OliveIsAWord]

I'm guessing it would be part of the is_some_with tracking issue, but I obviously defer to Mara Bos for the final say.

[OliveIsAWord]

I should also mention that, based on a rudimentary Godbolt test, this new method seems to optimize nicely.

[camsteffen]

Can we have is_err_or added with this?

I ran into a case the other day where I wanted to write:

    .filter(|r| r.is_err_or(|value| value.something()))
    .collect::<Result<_, _>();

[OliveIsAWord]

Can we have is_err_or added with this?

I think this case might be sufficiently covered by r.ok().is_none_or(...), and if we did add is_err_or, should we also add is_ok_or? Suffice to say, I think that would be a bikeshedding conversation for another PR.

[m-ou-se]

Thanks for your PR. I'm closing this as we decided not to add this method to Option. See rust-lang/libs-team#212.