New lint [redundant_at_rest_pattern]

[Centri3]

Closes #11011

It's always a great feeling when a new lint triggers on clippy itself 😄

changelog: New lint [redundant_at_rest_pattern]

[rustbot]

r? @giraffate

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[matthiaskrgr]

The first association when I read the title was "REST API" but I don't have any better ideas unfortunately. 😅

[matthiaskrgr]

The book uses the term @ binding. https://doc.rust-lang.org/book/ch18-03-pattern-syntax.html#-bindings

Maybe redundant_pattern_at redundant_at_pattern or redundant_at_binding ?

[Centri3]

rest is for the pattern on the right, i.e., .., which is being extraneously used to get every element of the slice binded to the local on the left. The at operator in particular isn't really the issue

[giraffate]

The rest pattern is reffered at https://doc.rust-lang.org/reference/patterns.html#rest-patterns. This lint detects the combination of @(at binding) and .. (rest pattern), so how about redundant_at_rest_pattern? (redundant_at_rest_pattern_binding is a little long?)

[Centri3]

I'm fine with redundant_at_rest_pattern

[giraffate]

Overall looks good, thanks! I made one comment.

[giraffate]

It warns irrefutable_let_patterns in this case, so can we add the case that simply print?

It would be better to detect irrefutable_let_patterns, but IMO this lint is still worth it as is.

Suggested change

	/// if let all = v {
	/// // NOTE: Type is a `Vec` here
	/// println!("all elements: {all:#?}");
	/// }
	/// if let all = v {
	/// // NOTE: Type is a `Vec` here
	/// println!("all elements: {all:#?}");
	/// }
	/// // or
	/// println!("all elements: {v:#?}");

[Centri3]

I think this is fine. Many lints clippy or not will still lint even if it'll give a warning, and then that lint will hopefully be applied as well by the programmer. Though yeah I'm fine with adding just the println!

[giraffate]

@bors r+

Thanks!

[bors]

📌 Commit 3376c71 has been approved by giraffate

It is now in the queue for this repository.

[bors]

⌛ Testing commit 3376c71 with merge 3d4c536...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: giraffate
Pushing 3d4c536 to master...