Use diagnostic items where possible
Clippy still uses a bunch of paths in places that could easily use already defined diagnostic items. This PR updates all references to such paths and also removes a bunch of them that are no longer needed after this cleanup.
Some paths are also used to construct new paths and can therefore not be removed that easily. I've added a doc comment to those instances that recommends the use of the diagnostic item where possible.
And that's it, cleaning crew signing off 🧹🗑️
---
changelog: none
(only internal improvements)
cc: #5393
Don't suggest doc(hidden) or unstable variants in wildcard lint
Clippy's wildcard lint would suggest doc(hidden) and unstable variants for non_exhaustive enums, even though those aren't part of the public interface (yet) and should only be matched on using a `_`, just like potential future additions to the enum. There was already some logic to exclude a *single* doc(hidden) variant. This extends that to all hidden variants, and also hides `#[unstable]` variants.
See https://github.com/rust-lang/rust/pull/85746#issuecomment-868886893
This PR includes https://github.com/rust-lang/rust-clippy/pull/7406 as the first commit.
Here's the diff that this PR adds on top of that PR: https://github.com/m-ou-se/rust-clippy/compare/std-errorkind...m-ou-se:doc-hidden-variants
---
*Please write a short comment explaining your change (or "none" for internal only changes)*
changelog: No longer suggest unstable and doc(hidden) variants in wildcard lint. wildcard_enum_match_arm, match_wildcard_for_single_variants
This fixes a bug where match_wildcard_for_single_variants produced a
bad suggestion where besides the missing variant, one or more hidden
variants were left.
This also adds tests to the ui-tests match_wildcard_for_single_variants
and wildcard_enum_match_arm to make sure that the correct suggestion is
produced.
match_single_binding: Fix invalid suggestion when match scrutinee has side effects
fixes#7094
changelog: `match_single_binding`: Fix invalid suggestion when match scrutinee has side effects
---
`Expr::can_have_side_effects` is used to determine the scrutinee has side effects, while this method is a little bit conservative for our use case. But I'd like to use it to avoid reimplementation of the method and too much heuristics. If you think this is problematic, then I'll implement a custom visitor to address it.
thread 'rustc' panicked at 'index out of bounds: the len is 0 but the index is 0', src/tools/clippy/clippy_lints/src/matches.rs:1595:53
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
I don't have a minimised testcase because I don't have time to reduce libstd down to a few lines right now.
Add `cloned_instead_of_copied` lint
Don't go cloning all willy-nilly.
Featuring a new `get_iterator_item_ty` util!
changelog: Add cloned_instead_of_copied lint
Closes#3870
Fix: redundant_pattern_matching drop order
Fixes#5746
A note about the change in drop order is added when the scrutinee (or any temporary in the expression) isn't known to be safe to drop in any order (i.e. doesn't implement the `Drop` trait, or contain such a type). There is a whitelist for some `std` types, but it's incomplete. Currently just `Vec<_>`, `Box<_>`, `Rc<_>` and `Arc<_>`, but only if the contained type is also safe to drop in any order.
Another lint for when the drop order changes could be added as allowed by default, but the drop order requirement is pretty subtle in this case. I think the note added to the lint should be enough to make someone think before applying the change.
changelog: Added a note to `redundant_pattern_matching` when the change in drop order might matter
