Tracking Issue for `#![feature(non_exhaustive_omitted_patterns_lint)]`

[Nadrieril]

This is a tracking issue for the non_exhaustive_omitted_patterns lint.
The feature gate for the issue is #![feature(non_exhaustive_omitted_patterns_lint)].

About tracking issues

Tracking issues are used to record the overall progress of implementation.
They are also used as hubs connecting to other relevant issues, e.g., bugs or open design questions.
A tracking issue is however not meant for large scale discussion, questions, or bug reports about a feature.
Instead, open a dedicated issue for the specific matter and add the relevant feature gate label.

Steps

• Implemented in Add non_exhaustive_omitted_patterns lint related to rfc-2008-non_exhaustive #86809
• Set a feature gate Feature gate the non_exhaustive_omitted_patterns lint #89428
• Adjust documentation (see instructions on rustc-dev-guide) — https://doc.rust-lang.org/rustc/lints/listing/allowed-by-default.html#non-exhaustive-omitted-patterns
• Clippy false positive False positive in match_same_arms + non_exhaustive_omitted_patterns rust-clippy#10327
• matches! false positive False positive in non_exhaustive_omitted_patterns: matches! #135137
• Stabilization PR (see instructions on rustc-dev-guide)

Unresolved Questions

• Lint name is potentially unclear New non_exhaustive_omitted_patterns lint exposes unstable and hidden enum variants. #89042 (comment)
• Lint message needs to be improved Feature gate the non_exhaustive_omitted_patterns lint #89428 (comment)

Implementation history

• Implemented in Add non_exhaustive_omitted_patterns lint related to rfc-2008-non_exhaustive #86809
• ICE was discovered in ICE related to non_exhaustive_omitted_patterns lint #89382 and fixed Fix ICE caused by non_exaustive_omitted_patterns struct lint #89423
• Feature gate PR Feature gate the non_exhaustive_omitted_patterns lint #89428
• A bug was discovered in New non_exhaustive_omitted_patterns lint exposes unstable and hidden enum variants. #89042 and fixed Fix: non_exhaustive_omitted_patterns by filtering unstable and doc hidden variants #89105
• Filter out unstable/hidden fields too non_exhaustive_omitted_patterns lint exposes unstable and hidden fields #89837
• Rework the lint to make it more consistent Lint non_exhaustive_omitted_patterns by columns #116734
• Warn users to not set the lint level on a single arm as was previously recommended Warn users who set non_exhaustive_omitted_patterns lint level on a match arm #117094

[DevinR528]

We'll need one more PR/check box: Add filtering of unstable and hidden fields to structs.

[Nadrieril]

In terms of the "documentation" bullet-point, the lint should turn up automatically on that list and I think that's enough. So we'll only need to check that it says the right thing once we've ironed out the name and message etc.

[DevinR528]

The question about not filtering doc(hidden) (and maybe this was only me feeling like it was odd) is kind of resolved for me since we unified the behavior so I no longer have the argument that filtering doc(hidden) variants/fields out of error and warning messages is not the norm (now it is done for all exhaustiveness checking).

I'm also curious about the stability of warning/error messages, I assume rust makes no guarantee so they can be improved quickly.

[Nadrieril]

Yeah, don't think there's any formal guarantee and they do change in small ways regularly