add manual_pop_if lint

[pbor]

Add a lint to detect when the recently added Vec::pop_if, VecDeque::pop_front_if, and VecDeque::pop_back_if are manually implemented.

changelog: add [manual_pop_if] lint

[rustbot]

r? @samueltardieu

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The reviewer was selected based on:

• Owners of files modified in this PR: 7 candidates
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• Random selection from Jarcho, dswij, llogiq, samueltardieu

[ada4a]

This is a very nicely made lint:) Left a couple suggestions, but nothing too major

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[pbor]

Thanks for the quick review! I hope I have addressed all the comments

[ada4a]

This is shaping up nicely:) Here's another round of stuff

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[samueltardieu]

@ada4a Don't hesitate to open an FCP on Zulip when you think this is ready.

[ada4a]

Thank you @samueltardieu :)

[pbor]

I think I have addressed the comments, if there is anything else that stands out let me know, otherwise I would like to start with this and treat the additional cases as future enhancements.

In particular, it would be nice to handle the case where the popped value is, since I believe that is common, but I am not quite sure on how to transform an if into if let Some(val) = pop_if while preserving the logic within the block.

[ada4a]

In particular, it would be nice to handle the case where the popped value is, since I believe that is common, but I am not quite sure on how to transform an if into if let Some(val) = pop_if while preserving the logic within the block.

I think it could help to look at some real-world examples, see how they would need to be transformed, and implement just those pattern-suggestion pairs, as a start. For this, you could use Lintcheck: you could open a test PR which makes the lint fire on more patterns, like any if-else with the condition containing vec.pop().is_some_and() (you don't need to worry about actually giving any suggestions), and then the Lintcheck diff would show you the new examples caught by the lint

[ada4a]

I'd say this is pretty much ready:) Just a few notes left

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[rustbot]

Reminder, once the PR becomes ready for a review, use @rustbot ready.

[rustbot]

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[pbor]

I hope I fixed all the comments (thanks for the review)!

I will need to look at the LintCheck suggestion next week

[ada4a]

First of all, let's deal with rustbot:

@rustbot reviewer

Now, let's give this a go:)

FCP started at #clippy > FCP: `manual_pop_if`