Fix non_camel_case_types for screaming single-words

[sjwang05]

Fixes #116336

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[rustbot]

Some changes occurred in src/tools/rustfmt

cc @rust-lang/rustfmt

[rustbot]

This PR changes Stable MIR

cc @oli-obk, @celinval, @spastorino

[petrochenkov]

This does look like an improvement to me.
I'm just not sure whether we can make this change at this point though. after treating ABC as a standard style for many years.
@rustbot author

[rustbot]

This PR changes Stable MIR

cc @oli-obk, @celinval, @spastorino

[rustbot]

These commits modify compiler targets.
(See the Target Tier Policy.)

Some changes occurred in compiler/rustc_codegen_cranelift

cc @bjorn3

[sjwang05]

Thanks for all the feedback!

I'm just not sure whether we can make this change at this point though. after treating ABC as a standard style for many years.

I can definitely see that--I think I've fixed most of the violations I could find, though it feels like new ones keep popping up whenever I do 😅 . If you (or anyone else) see fit, I'd be more than willing to close this PR because of this.

@rustbot review

[petrochenkov]

I'm going to nominate this for the lang team.

A relaxed version of this PR could be bumping the length limit from 3 letters to 4.
E.g. ABC would still be considered camel case, but ABCD/ABCDF/etc not.

[bors]

☔ The latest upstream changes (presumably #116855) made this pull request unmergeable. Please resolve the merge conflicts.

[scottmcm]

Some prior art: C#'s rules require upper for two-letter acronyms, like System.IO but not for longer ones, like System.Xml.

(No idea if that's good or not, but it came to mind.)

[scottmcm]

We discussed this in the lang triage meeting today.

While many felt that most of the changes in the PR "felt more Rust-y", there was lots of concern about how much churn this might be pushing on people, based on all the edits needed in the PR.

Can you say more about the motivation here? How essential is this?

---

Personally, the note from #116389 (comment) about maybe moving the threshold for complaining about it seems potentially interesting as a way to have this handle the most egregious cases without being so noisy.

[sjwang05]

Can you say more about the motivation here? How essential is this?

I'd say the main motivation here (as mentioned in the original issue) is just to be more compliant with RFC430, though I wouldn't say it's essential, especially for 3-letter screaming words.

Personally, the note from #116389 (comment) about maybe moving the threshold for complaining about it seems potentially interesting as a way to have this handle the most egregious cases without being so noisy.

I agree--I think raising the limit to 4 upper-case characters would be a good compromise, though I'll leave the final call on what to do up to you all.

[traviscross]

We discussed this in the T-lang meeting today alongside #60570. The feeling was that simple heuristics aren't powerful enough to reliably check whether or not some string is following the camel case style since, e.g., a series of upper-case letters may be a series of single letter words or may be an initialism (rather than acronym) that it may be more appropriate to leave capitalized. As @joshtriplett explains over in #60570:

I don't think we should encourage INTEGER_1, but I do think it's completely valid to write arbitrarily-long strings of capital letters in "camel case". If someone writes IFAClient (example made up on the spot), we have no way of knowing if that's "IFA Client" (in which case officially by our rules you're "supposed" to write IfaClient), or "I F A Client" (e.g. Iterator of Futures of Async-wrapped Client). And since we can't distinguish those, we should be more permissive.

And as @scottmcm noted:

rb"foo" being an RBString and not getting linted seems entirely fine.

People also felt it might just be too opinionated for rustc to enforce Http and Html over HTTP and HTML, and that if desired, these may be better as clippy lints. People were also concerned about unnecessary churn here.

With this context, a proposal for FCP close will be forthcoming.

[tmandry]

On the basis of the above comment,

@rfcbot fcp close

[rfcbot]

Team member @tmandry has proposed to close this. The next step is review by the rest of the tagged team members:

• @joshtriplett
• @nikomatsakis
• @pnkfelix
• @scottmcm
• @tmandry

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

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[scottmcm]

@rfcbot reviewed

But as I said earlier (#116389 (comment)), I might still be interested in different tweaks at different points in the "how confident can we be" spectrum. I don't have enough data to know where that would be, but at some point I think the odds that IOMGWTFBBQWidget is actually legitimate camel case are low enough that I'd be fine linting against it, even if technically it could have false positives. (That said, the odds of that catching anything meaningful might also be low enough that doing work for it wouldn't be worth bothering either. I don't know.)

[rfcbot]

🔔 This is now entering its final comment period, as per the review above. 🔔

[rfcbot]

The final comment period, with a disposition to close, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.