Factor out clippy_utils crate

[smoelius]

As discussed in #6746, this PR factors out clippy_lints::utils as its own crate, clippy_utils .

This change will allow clippy_utils to be used in lints outside of Clippy.

There is no plan to publish this crate on crates.io (see #6746 (comment)). Dependent crates should obtain it from GitHub.

changelog: Factor out clippy_utils so it can be used by external tools (not published)

[rust-highfive]

r? @phansch

(rust-highfive has picked a reviewer for you, use r? to override)

[Manishearth]

(we should still squat the crate on crates.io, though)

[flip1995]

+1 for squatting that crate name, but that isn't a blocker for this PR. And we should only publish a dummy like clippy_dummy to avoid confusion.

I also think there are some references to utils in the doc dir.

[flip1995]

Weird that git doesn't recognize that this file was just moved 🤔

[smoelius]

There's a small difference:

3c3
< use crate::utils::{clip, sext, unsext};
---
> use crate::{clip, sext, unsext};

[flip1995]

Yeah, that's fine, but git manged to figure this out for other files. That's what confuses me.

[camsteffen]

You can tweak the git rename sensitivity (docs)

[smoelius]

I also think there are some references to utils in the doc dir.

Thanks. I think I got them all: smoelius@3341e3d

[phansch]

r? @flip1995 (I'm short on time this week)

[bors]

☔ The latest upstream changes (presumably #6754) made this pull request unmergeable. Please resolve the merge conflicts.

[flip1995]

This needs a rebase.

[bors]

☔ The latest upstream changes (presumably #6573) made this pull request unmergeable. Please resolve the merge conflicts.

[smoelius]

I rebased this again, following #6573. Please let me know if there is anything I can do to make the review go more smoothly.

[flip1995]

LGTM. But I want a second approval on this, since it is a bigger change @rust-lang/clippy

[flip1995]

@bors r=flip1995,oli-obk

EDIT: Accidentally shipped oli-obk with obi-wan kenobi.

[bors]

📌 Commit ab7381f has been approved by flip1995,obi-obk

[bors]

⌛ Testing commit ab7381f with merge 489c4f0...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: flip1995,obi-obk
Pushing 489c4f0 to master...

[matthiaskrgr]

Mmh, looks like this broke some part of CI ..?
https://github.com/rust-lang/rust-clippy/runs/1968986956#step:7:494

[matthiaskrgr]

Fix attempt at #6785

[smoelius]

Thank you @matthiaskrgr. An alternative solution (I think) is #6786.

@flip1995 argued that declare_clippy_lint should not be made public. I suppose the same argument could be made that Conf should not be made public. I don't have strong feelings either way.

[smoelius]

Actually, because there is more to conf.rs than just Conf, I think I prefer #6785. But I could split up conf.rs and amend #6786, if preferred.

[flip1995]

I prefer the solution by @smoelius. I don't think publishing conf.rs helps anyone. It is really specific to Clippy.

[smoelius]

Thank you, very sincerely, @oli-obk, @Manishearth, @matthiaskrgr, and especially @flip1995.