Use is_some_and when appropriate

[pcd1193182]

What it does

The lint would detect cases where the new Option function is_some_and would be appropriate. Examples would be places where map() converts an Option<T> into an Option<bool> and then unwrap_or(false) is used. The library function is still experimental, but once it's stable, this would be a useful modernization suggestion.

Lint Name

option_is_some_with

Category

complexity

Advantage

Reduces function calls (even if they would optimize down), increases clarity.

Drawbacks

Low priority, since the existing approaches are functional, if less idiomatic/aesthetic.

Example

let x: Option<int> = Some(7);
x.map(|val| val > 5).unwrap_or(false)

Could be written as:

let x: Option<int> = Some(7);
x.is_some_and(|val| val > 5)

[giraffate]

There is no method is_some_with on Option. Do you mean is_some_and?

[pcd1193182]

Sorry, that's correct. The feature is called is_some_with, which is what confused me.

EDIT: Updated the original comment.

[JoelMon]

Is there a hurry to get this done? I would love to learn how to implement lint's.

If this is a good match for a beginner I would love to learn how to implement this.

[Rqnsom]

I'm also looking for good-first-issues since I'm also a beginner, but I feel that a good-first-issue items are never supposed to be urgent. So that we the beginners could take our time to do it at our pace - since learning should not be stressful. So, I think you are free to claim it and see how it goes! :-)

Clippy veterans can correct me if I said anything wrong.

[xFrednet]

Hey, welcome to Clippy 👋. This issue is not urgent, so you're welcome to claim it and take your time. If you have questions, you're also welcome to ask. Please don't hesitate to ping anyone of us (sometimes we miss questions in issues, if nobody mentions us)

Some more context, about what is urgent, in case you're interested: A new version of Clippy is released every 6 weeks. There are only very few things which are kind of urgent, and these are mostly handled by maintainers. (like writing the changelog and syncing changes with the rust repo). Some issues have a slightly higher priority, like crashes or very common false positives. But even these can be handled differently if nobody wants to fix them. The wonderful part is that Clippy and other rust projects are about building cool software and very little about deadlines and releases :)

[JoelMon]

@Rqnsom, @xFrednet Thank you for being so welcoming! :)

How do I claim a lint? Do I do something like @bors claim? I think I saw someone use a command like that once to claim a lint but I can't seem to find it in https://bors.rust-lang.org/

[xFrednet]

For that, we have our lovely rustbot. Just include @rustbot claim in a comment, to asking an issue to you. See https://rustc-dev-guide.rust-lang.org/rustbot.html in case you're interested in what else you can do with @rustbot 🙃

[JoelMon]

@rustbot claim

[JoelMon]

I'm noticing that the documentation is pretty fragmented... That looks like a good easy (non technical) project to look at next. lol

[xFrednet]

Yeah, Clippy sadly also has some areas which are not documented at all. We're recently made some good progress on that, but documentation improvements are always good and welcome!

[kadiwa4]

This should also trigger on .map_or(false, …), .map(…).unwrap_or_default(), .map(…) == Some(true) and .filter(…).is_some().

[xFrednet]

It would be cool if all of these causes would be caught. For the start, it might be better to focus on one and add the others later :)

[TheCodingWombat]

@JoelMon Any progress on this? I would also love to try it as my first clippy lint, and my first contribution to an open source project.

[JoelMon]

@JoelMon Any progress on this? I would also love to try it as my first clippy lint, and my first contribution to an open source project.

I haven't been able to take a crack at it and won't be able to any time soon. Go ahead and give it a go. Let me know if I have to do someone on my end to give up claim or what not.

Hope you success and enjoyment to your first contribution!

[TheCodingWombat]

@rustbot claim

[TheCodingWombat]

@xFrednet I was trying to implement this lint, but then I found out about an existing lint option_map_unwrap_or. Should this be its own self contained lint (and if so, how do we then make clippy use this lint's suggestion instead of that of option_map_unwrap_or)? Or should we just add some different suggestions for different values of the unwrap_or argument to option_map_unwrap_or?

[xFrednet]

Hey @TheCodingWombat, good catch! This lint is more specific in the sense that it specially detects boolean conversions. I think adding logic to the mentioned lint, to suggest is_some_and() if the map is used for a boolean conversion, would be the best step.

Small sidenote, the lint has been renamed and the current name is clippy::map_unwrap_or :)

[TheCodingWombat]

@xFrednet What command do I use to run a single uitest? I tried cargo uitest -- --test-args=test_name.rs, but that doesn't work, also not without the --, even though this was the suggestion of the test output. I think this is because programs are passed to one another and the CLI arguments need to be passed from one to the other, but I don't know how.

[xFrednet]

@TheCodingWombat The interface is a bit weird, as the framework we use doesn't support cli arguments. Instead, a TESTNAME environment value is used. Try TESTNAME=test_file.rs cargo uitest

[frewsxcv]

Here's another usage that could use is_some_and:

https://github.com/rust-lang/rust/blob/0978711950b77582e4f8f334f6e9848d48ab7790/compiler/rustc_lint/src/nonstandard_style.rs#L69-L72

This could be:

if u.next().is_some_and(|u| l != u) {
    return true;
}

[xFrednet]

A start of this implementation can be found in this PR #10102 which was closed due to inactivity. If someone else wants to pick it up, I'm happy to help where I can :)

[chansuke]

@rustbot claim

[disco07]

@rustbot claim

[darklyspaced]

@rustbot claim