Disable "if_not_else" lints from firing on else-ifs

[ahmedkrmn]

Fixes #7892

1. Convert ['if_not_else'] to LateLintPass and use clippy_utils::is_else_clause for checking.
2. Update tests.

changelog: [if_not_else] now ignores else if statements.

[rust-highfive]

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

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[Manishearth]

@bors r+

[bors]

📌 Commit 282d313 has been approved by Manishearth

[bors]

⌛ Testing commit 282d313 with merge 47d1bec...

[Manishearth]

@bors r-

CI is failing

[bors]

💔 Test failed - checks-action_test

[xFrednet]

The error can be seen here It looks like a false positive, it might have something to do with how while loops are desugared 🤔

Could you also include a changelog entry in your PR, the CI will otherwise fail during the merge. You can just add something like this: "changelog: [if_not_else] now ignores else if statements" 🙃

[dswij]

The error can be seen here It looks like a false positive, it might have something to do with how while loops are desugared 🤔

This might makes sense since it's now using a late pass rather than an early pass

[xFrednet]

Yes, but it seems weird that is_else_clause would cause this FP, as it's also used more often.

[ahmedkrmn]

Thanks @Manishearth, @xFrednet and @dswij!

Yes, but it seems weird that is_else_clause would cause this FP, as it's also used more often.

@xFrednet, I've removed the is_else_clause call and reverted back to the old behavior but with using LateLintPass instead of EarlyLintPass and the test is still failing on the same while loop. I will continue debugging and see if I can find the culprit.

[xFrednet]

That's good to know! Reach out, if you need more help debugging 🙃

[camsteffen]

This will fix it if my suspicion is right - changing to LateLintPass means that desugaring occurs before the lint runs. from_expansion will catch desugaring in addition to macros.

Suggested change

	if in_external_macro(cx.sess(), item.span) {
	if item.span.from_expansion() {

[ahmedkrmn]

Thanks @camsteffen. This is my first time working with rustc. I didn't know this life saver function existed!
I've been debugging the issue. After dumping the expression trees, I could see that the while loop was indeed represented as an ExprKind::If when using LateLintPasswhich caused this problem. I thought about reverting back to EarlyLintPass and looking for a workaround, but your comment came just in time!

[Manishearth]

@bors r+

[bors]

📌 Commit 2f327aa has been approved by Manishearth

[bors]

⌛ Testing commit 2f327aa with merge 4c70c18...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: Manishearth
Pushing 4c70c18 to master...