[redundant_pattern_matching]: lint if let true, while let true, matches!(.., true)

[y21]

Closes #11917

This could also lint e.g. if let (true, true, false) = (a, b, c) and suggest if a && b && c, but that's a change in semantics (going from eager to lazy, so I just left it out for now. Could be a future improvement.

changelog: [redundant_pattern_matching]: lint if let true, while let true, matches!(.., true)

[rustbot]

r? @llogiq

(rustbot has picked a reviewer for you, use r? to override)

[llogiq]

Why only true and not also false? Otherwise this looks good and for the sake of avoiding rebase work, we can do that in a follow-up PR.

@bors r+

[bors]

📌 Commit bc22407 has been approved by llogiq

It is now in the queue for this repository.

[bors]

⌛ Testing commit bc22407 with merge b918434...

[y21]

Why only true and not also false?

It should also lint false, forgot to mention that in the title/description. Or are you referring to something else?

rust-clippy/tests/ui/redundant_pattern_matching_if_let_true.stderr

Lines 13 to 14 in bc22407

	LL | if let false = k > 5 {}
	| ^^^^^^^^^^^^^^^^^ help: consider using the condition directly: `!(k > 5)`

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: llogiq
Pushing b918434 to master...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: llogiq
Pushing b918434 to master...