Fix issue 11223: add check for identical guards in lint match_same_arms

[roife]

fixes #11223

In the current match_same_arms implementation, if arms have guards, they are considered different. This commit adds equality checking for guards: arms are now considered equivalent only when they either both have no guards or their guards are identical.

The portion responsible for checking guard equality is refactored to reuse the existing code for checking body equality. This is abstracted into a function called check_eq_with_pat. To optimize performance, check_same_guard and check_same_body here use closures for lazy evaluation, ensuring that the calculation is only performed when !(backwards_blocking_idxs...) is true.

changelog: [match_same_arms]: Add check for identical guards

[rustbot]

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

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[bors]

☔ The latest upstream changes (presumably #12306) made this pull request unmergeable. Please resolve the merge conflicts.

[Alexendoo]

Thank you! Sorry for taking a while to get around to this

@bors r+

[bors]

📌 Commit 087c7c8 has been approved by Alexendoo

It is now in the queue for this repository.

[bors]

⌛ Testing commit 087c7c8 with merge fa2a3c5...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: Alexendoo
Pushing fa2a3c5 to master...