Add excessive_nesting lint

[Centri3]

changelog: new lint [excessive_nesting]

[rustbot]

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[Centri3]

ok, I see an issue with this. local bindings seem to be checked as well even if they're a block, which makes sense. this means, even if the actual code never reaches above column 100, it'll still be triggered if the length of the entire block is above 100. Not ideal... I'll check back on here later with hopefully the knowledge needed to eliminate that.

[Alexendoo]

Although it's unstable rustfmt does have an option to error on lines that go above the max_width - error_on_line_overflow. We want to avoid doing things that are/could be covered by rustfmt

For indentation that does seem like something more in our area, at least I wouldn't expect for rustfmt to add an option for that. Does that sound reasonable @flip1995?

[Centri3]

Although it's unstable rustfmt does have an option to error on lines that go above the max_width - error_on_line_overflow. We want to avoid doing things that are/could be covered by rustfmt

Yeah, I remembered that option and so excessive_width seems unnecessary. I'll remove it in a later commit

[flip1995]

For general feedback, please see Zulip. Also please discuss the IF we should add this lint there.

Implementing a lint on number of whitespaces is not a good idea. Maybe some people use 2 whitespace indentation vs 4. Then this lint would behave differently. But if you try to determine indentation by analyzing statements, see Zulip and #3793 (comment)

FYI @felix91gr: This again is an attempt at doing something in the direction of cognitive/cyclomatic complexity. I like to page you in on those discussions, if you're still around and interested (either here, on Zulip or not at all) 😄

[Centri3]

Ok, I think this is ready! @Alexendoo, feel free to review this whenever you can and once consensus on whether this should be added has been reached 🙂 the current implementation is a bit verbose but I'm not sure if it's possible to get it better.

I'll also write tests and the description later, once I know whether this should be added.

[bors]

☔ The latest upstream changes (presumably #10578) made this pull request unmergeable. Please resolve the merge conflicts.

[Alexendoo]

👋

[Centri3]

I'll apply these changes tomorrow 🙂 thanks! Glad to see this could've been done better

[Alexendoo]

Thanks! @bors r+

[bors]

📌 Commit 6afb355 has been approved by Alexendoo

It is now in the queue for this repository.

[bors]

⌛ Testing commit 6afb355 with merge 476efe9...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: Alexendoo
Pushing 476efe9 to master...