List configuration values can now be extended instead of replaced
I've seen some `clippy.toml` files, that have a few additions to the default list of a configuration and then a copy of our default. The list will therefore not be updated, when we add new names. This change should make it simple for new users to append values instead of replacing them.
I'm uncertain if the documentation of the `".."` is apparent. Any suggestions are welcome. I've also check that the lint list displays the examples correctly.
<details>
<summary>Lint list screenshots</summary>
</details>
---
changelog: enhancement: [`doc_markdown`]: Users can now indicate, that the `doc-valid-idents` should extend the default and not replace it
changelog: enhancement: [`blacklisted-name`]: Users can now indicate, that the `blacklisted-names` should extend the default and not replace it
Closes: #8877
That's it. Have a fantastic weekend to everyone reading this. Here is a cookie 🍪
Add new lint [`needless_parens_on_range_literals`]
changelog: Adds a new lint [`needless_parens_on_range_literals`] to warn on needless braces on literals in a range statement
For example, the lint would catch
```log
error: needless parenthesis on range literals can be removed
--> $DIR/needless_parens_on_range_literals.rs:8:13
|
LL | let _ = ('a')..=('z');
| ^^^^^ help: try: `'a'`
|
= note: `-D clippy::needless-parens-on-range-literals` implied by `-D warnings`
```
improve [`for_loops_over_fallibles`] to detect the usage of iter, iter_mut and into_iterator
fix#6762
detects code like
```rust
for _ in option.iter() {
//..
}
```
changelog: Improve [`for_loops_over_fallibles`] to detect `for _ in option.iter() {}` or using `iter_mut()` or `into_iterator()`.
Remove the unneeded wrapping and unwrapping in suggestion creation.
Collecting to Option<Vec<_>> only returns None if one of the elements is
None and that is never the case here.
fix(manual_find_map and manual_filter_map): check clone method
close#8920
Added conditional branching when the clone method is used.
Thank you in advance.
---
changelog: check `clone()` and other variant preserving methods in [`manual_find_map`] and [`manual_filter_map`]
When setting suggestion for significant_drop_in_scrutinee, add suggestion for MoveAndClone for non-ref
When trying to set the current suggestion, if the type of the expression
is not a reference and it is not trivially pure clone copy, we should still
trigger and emit a lint message. Since this fix may require cloning an
expensive-to-clone type, do not attempt to offer a suggested fix.
This change means that matches generated from TryDesugar and AwaitDesugar
would normally trigger a lint, but they are out of scope for this lint,
so we will explicitly ignore matches with sources of TryDesugar or
AwaitDesugar.
changelog: Update for ``[`significant_drop_in_scrutinee`]`` to correctly
emit lint messages for cases where the type is not a reference *and*
not trivially pure clone copy.
changelog: [`significant_drop_in_scrutinee`]: No longer lint on Try `?`
and `await` desugared expressions.
remove `large_enum_variant` suggestion for `Copy` types
Replaces the (erroneous) suggestion on `large_enum_variant` for `Copy` types by a note. This fixes#8894.
---
changelog: none
[1/N] Implement Arithmetic lint
Assuming that https://github.com/rust-lang/rust-clippy/issues/8903 is OK, this PR starts the creation of the `Arithmetic` lint with configurable types.
My current struggle to get a rustc review inspired me to create smaller PRs in order to easy review and make merges as fast as possible. So the first step here only moves the `arithmetic.rs` file to `numeric_arithmetic.rs` to make room for the new lint.
--
changelog: none
Make docs more consistent
changelog: none
This just fixes some docs to make them more consistent. I mostly just changed `// Good`, `// Bad`, etc to `Use instead:`.
Set correct `ParamEnv` for `derive_partial_eq_without_eq`
fixes#8867
changelog: Handle differing predicates applied by `#[derive(PartialEq)]` and `#[derive(Eq)]` in `derive_partial_eq_without_eq`
new lint: `borrow_deref_ref`
changelog: ``[`borrow_deref_ref`]``
Related pr: #6837#7577
`@Jarcho` Could you please give a review?
`cargo lintcheck` gives no false negative (but tested crates are out-of-date).
TODO:
1. Not sure the name. `deref_on_immutable_ref` or some others?
`SourceFile::lines` is a big part of metadata. It's stored in a compressed form
(a difference list) to save disk space. Decoding it is a big fraction of
compile time for very small crates/programs.
This commit introduces a new type `SourceFileLines` which has a `Lines`
form and a `Diffs` form. The latter is used when the metadata is first
read, and it is only decoded into the `Lines` form when line data is
actually needed. This avoids the decoding cost for many files,
especially in `std`. It's a performance win of up to 15% for tiny
crates/programs where metadata decoding is a high part of compilation
costs.
A `Lock` is needed because the methods that access lines data (which can
trigger decoding) take `&self` rather than `&mut self`. To allow for this,
`SourceFile::lines` now takes a `FnMut` that operates on the lines slice rather
than returning the lines slice.
Fix `manual_range_contains` false negative with chains of `&&` and `||`
Fixes#8745
Since the precedence for `&&` is the same as itself the HIR for a chain of `&&` ends up with a right skewed tree like:
```
&&
/ \
&& c2
/ \
... c1
```
So only the leftmost `&&` was actually "fully" checked, the top level was just `c2` and `&&` so the `manual_range_contains` lint won't apply. This change makes it also check `c2` with `c1`.
There's a bit of a hacky solution in the [second commit](257f09776a) to check if the number of open/closing parens in the snippet match. This is to prevent a case like `((x % 2 == 0) || (x < 0)) || (x >= 10)` from offering a suggestion like `((x % 2 == 0) || !(0..10).contains(&x)` which now won't compile.
Any suggestions for that paren hack welcome, kinda new to working on this so not too sure about possible solutions :) it's weird because I don't know how else to check for parens in HIR considering they're removed when lowering AST.
changelog: Fix [`manual_range_contains`] false negative with chains of `&&` and `||`
Don't lint `useless_transmute` on types with erased regions
fixes#6356fixes#3340fixes#2906
This should get a proper fix at some point, but this at least gets the lint running on some types.
cc #5343
changelog: Don't lint `useless_transmute` on types with erased regions
`cast_abs_to_unsigned`: do not remove cast if it's required
Fixes#8873
If `iX` is not cast to `uX` then keep the cast rather than removing it
changelog: [`cast_abs_to_unsigned`]: do not remove cast if it's required
needless_late_init: fix ICE when all branches return the never type
Fixes#8911
When the assignment is done in a match guard or the if condition and all of the branches return the never type `assignment_suggestions` would return an empty `Vec` which caused the ICE. It now returns `None` in that scenario
Also moves some tests to the top of the file
changelog: ICE Fixes: [`needless_late_init`] #8911
Fix `[use_self]` false negative with on struct and tuple struct patterns
fixes#8845
changelog: Triggered the warning for ``[`use_self`]`` on `TupleStruct` and `Struct` patterns, whereas currently it's only triggered for `Path` patterns
Fix `empty_line_after_outer_attribute` false positive
This PR fixes a false positive in `empty_line_after_outer_attribute`.
Here is a minimal example that trigger the FP:
```rust
#[derive(clap::Parser)]
#[clap(after_help = "This ia a help message.
You're welcome.
")]
pub struct Args;
```
changelog: PF: [`empty_line_after_outer_attribute`]: No longer lints empty lines in inner string values.
Introduce `allow-dbg-in-tests` config value
related to: Issue #8758, PR https://github.com/rust-lang/rust-clippy/pull/8838
changelog: Introduced `allow-dbg-in-tests` config value. [dbg_macro] does not allow `dbg!` in test code by default.
When trying to set the current suggestion, if the type of the expression
is not a reference and it is not trivially pure clone copy, we should still
trigger and emit a lint message. Since this fix may require cloning an
expensive-to-clone type, do not attempt to offer a suggested fix.
This change means that matches generated from TryDesugar and AwaitDesugar
would normally trigger a lint, but they are out of scope for this lint,
so we will explicitly ignore matches with sources of TryDesugar or
AwaitDesugar.
changelog: Update for [`significant_drop_in_scrutinee`] to correctly
emit lint messages for cases where the type is not a reference and
not trivially pure clone copy.
`get_last_with_len`: lint `VecDeque` and any deref to slice
changelog: [`get_last_with_len`]: lint `VecDeque` and any deref to slice
Previously only `Vec`s were linted, this will now catch any usages on slices, arrays, etc. It also suggests `.back()` for `VecDeque`s
Also moves the lint into `methods/`
`identity_op`: add parenthesis to suggestions where required
changelog: [`identity_op`]: add parenthesis to suggestions where required
Follow up to #8730, wraps the cases we can't lint as-is in parenthesis rather than ignoring them
Catches a couple new FPs with mixed operator precedences and `as` casts
```rust
// such as
0 + { a } * 2;
0 + a as usize;
```
The suggestions are now applied using `span_lint_and_sugg` rather than appearing in just the message and have a `run-rustfix` test
Refactor call terminator to always include destination place
In #71117 people seemed to agree that call terminators should always have a destination place, even if the call was guaranteed to diverge. This implements that. Unsurprisingly, the diff touches a lot of code, but thankfully I had to do almost nothing interesting. The only interesting thing came up in const prop, where the stack frame having no return place was also used to indicate that the layout could not be computed (or similar). I replaced this with a ZST allocation, which should continue to do the right things.
cc `@RalfJung` `@eddyb` who were involved in the original conversation
r? rust-lang/mir-opt
Lifetime variance fixes for clippy
#97287 migrates rustc to a `Ty` type that is invariant over its lifetime `'tcx`, so I need to fix a bunch of places that assume that `Ty<'a>` and `Ty<'b>` can be shortened to some common lifetime.
This is doable, since everything is already `'tcx`, so all this PR does is be a bit more explicit that elided lifetimes are actually `'tcx`.
Split out from #97287 so the clippy team can review independently.
Drop Tracking: Implement `fake_read` callback
This PR updates drop tracking's use of `ExprUseVisitor` so that we treat `fake_read` events as borrows. Without doing this, we were not handling match expressions correctly, which showed up as a breakage in the `addassign-yield.rs` test. We did not previously notice this because we still had rather large temporary scopes that we held borrows for, which changed in #94309.
This PR also includes a variant of the `addassign-yield.rs` test case to make sure we continue to have correct behavior here with drop tracking.
r? `@nikomatsakis`
Rustup
`@rust-lang/clippy,` `@Jarcho,` `@dswij,` `@Alexendoo.` Could someone review this? It should be pretty straight forward since it's just a sync. I think it's also fine if either one of `@Jarcho,` `@dswij,` `@Alexendoo` approves this, as these are usually not reviewed. I just want to make sure that I didn't break something obvious 🙃
It should be enough to look at the merge commit 🙃
changelog: none
changelog: move [`significant_drop_in_scrutinee`] to `suspicious`
[dbg_macro] tolerates use of `dbg!` in items which have `#[cfg(test)]` attribute
fix: #8758
changelog: [dbg_macro] tolerates use of `dbg!` in items with `#[cfg(test)]` attribute
Improve "unknown field" error messages
Fixes#8806
Sample output:
```
error: error reading Clippy's configuration file `/home/smoelius/github/smoelius/rust-clippy/clippy.toml`: unknown field `foobar`, expected one of
allow-expect-in-tests enable-raw-pointer-heuristic-for-send standard-macro-braces
allow-unwrap-in-tests enforced-import-renames third-party
allowed-scripts enum-variant-name-threshold too-large-for-stack
array-size-threshold enum-variant-size-threshold too-many-arguments-threshold
avoid-breaking-exported-api literal-representation-threshold too-many-lines-threshold
await-holding-invalid-types max-fn-params-bools trivial-copy-size-limit
blacklisted-names max-include-file-size type-complexity-threshold
cargo-ignore-publish max-struct-bools unreadable-literal-lint-fractions
cognitive-complexity-threshold max-suggested-slice-pattern-length upper-case-acronyms-aggressive
cyclomatic-complexity-threshold max-trait-bounds vec-box-size-threshold
disallowed-methods msrv verbose-bit-mask-threshold
disallowed-types pass-by-value-size-limit warn-on-all-wildcard-imports
doc-valid-idents single-char-binding-names-threshold
at line 1 column 1
```
You can test this by (say) adding `foobar = 42` to Clippy's root `clippy.toml` file, and running `cargo run --bin cargo-clippy`.
Note that, to get the terminal width, this PR adds `termize` as a dependency to `cargo-clippy`. However, `termize` is also [how `rustc_errors` gets the terminal width](481db40311/compiler/rustc_errors/src/emitter.rs (L1607)). So, hopefully, this is not a dealbreaker.
r? `@xFrednet`
changelog: Enhancements: the "unknown field" error messages for config files now wraps the field names.
add suggestions to rc_clone_in_vec_init
A followup to https://github.com/rust-lang/rust-clippy/pull/8769
I also switch the order of the 2 suggestions, since the loop initialization one is probably the common case.
`@xFrednet` I'm not letting you guys rest for a minute 😅
changelog: add suggestions to [`rc_clone_in_vec_init`]
`undocumented_unsafe_blocks` does not trigger on unsafe trait impls
Closes#8505
changelog: This lint checks unsafe impls NOT from macro expansions and checks ones in macro declarations.
~~`unsafe impl`s from macro invocations don't trigger the lint for now.~~
~~This lint checks unsafe impls from/not from macro expansions~~
Don't lint `vec_init_then_push` when further extended
fixes#7071
This will still lint when a larger number of pushes are done (four currently). The exact number could be debated, but this is more readable then a sequence of pushes so it shouldn't be too large.
changelog: Don't lint `vec_init_then_push` when further extended.
changelog: Remove `mut` binding from `vec_init_then_push` when possible.
Add EarlyBinder
Chalk has no concept of `Param` (e0ade19d13/chalk-ir/src/lib.rs (L579)) or `ReEarlyBound` (e0ade19d13/chalk-ir/src/lib.rs (L1308)). Everything is just "bound" - the equivalent of rustc's late-bound. It's not completely clear yet whether to move everything to the same time of binder in rustc or add `Param` and `ReEarlyBound` in Chalk.
Either way, tracking when we have or haven't already substituted out these in rustc can be helpful.
As a first step, I'm just adding a `EarlyBinder` newtype that is required to call `subst`. I also add a couple "transparent" `bound_*` wrappers around a couple query that are often immediately substituted.
r? `@nikomatsakis`
Fix redundant_allocation warning for Rc<Box<str>>
changelog: [`redundant_allocation`] Fixes#8604
Fixes false positives where a fat pointer with `str` type was made thin by another allocation, but that thinning allocation was marked as redundant
This PR has implemented improved representation.
- Use "lib" instead of "lifb"
- Use "triggered" instead of "triggere"
- Use "blacklisted_name" instead of "blackisted_name"
- Use "stabilization" instead of "stabilisation"
- Use "behavior" instead of "behaviour"
- Use "target" instead of "tartet"
- Use "checked_add" instead of "chcked_add"
- Use "anti-pattern" instead of "antipattern"
- Use "suggestion" instead of "suggesttion"
- Use "example" instead of "exampel"
- Use "Cheat Sheet" instead of "Cheatsheet"
New lint: [`derive_partial_eq_without_eq`]
Introduces a new lint, [`derive_partial_eq_without_eq`].
See: #1781 (doesn't close it though).
changelog: add lint [`derive_partial_eq_without_eq`]
Replace `#[allow]` with `#[expect]` in Clippy
Hey `@rust-lang/clippy,` `@Alexendoo,` `@dswij,` I'm currently working on the expect attribute as defined in [Rust RFC 2383](https://rust-lang.github.io/rfcs/2383-lint-reasons.html). With that, an `#[allow]` attribute can be replaced with a `#[expect]` attribute that suppresses the lint, but also emits a warning, if the lint isn't emitted in the expected scope.
With this PR I would like to test the attribute on a project scale and Clippy obviously came to mind. This PR replaces (almost) all `#[allow]` attributes in `clippy_utils` and `clippy_lints` with the `#[expect]` attribute. I was also able to remove some allows since, the related FPs have been fixed 🎉.
My question is now, are there any concerns regarding this? It's still okay to add normal `#[allow]` attributes, I see the need to nit-pick about that in new PRs, unless it's actually a FP. Also, I would not recommend using `#[expect]` in tests, as changes to a lint could the trigger the expect attribute in other files.
Additionally, I've noticed that Clippy has a bunch of `#[allow(clippy::too_many_lines)]` attributes. Should we maybe allow the lint all together or increase the threshold setting? To me, it seems like we mostly just ignore it in our code. 😅🙃
---
changelog: none
r? `@flip1995` (I've requested you for now, since you're also helping with reviewing the expect implementation. You are welcome to delegate this PR, even if it should be a simple review 🙃 )
Track if a where bound comes from a impl Trait desugar
With https://github.com/rust-lang/rust/pull/93803 `impl Trait` function arguments get desugared to hidden where bounds. However, Clippy needs to know if a bound was originally a `impl Trait` or an actual bound. This adds a field to the `WhereBoundPredicate` struct to keep track of this information during AST->HIR lowering.
r? `@cjgillot`
cc `@estebank` (as the reviewer of #93803)
Create clippy lint against unexpectedly late drop for temporaries in match scrutinee expressions
A new clippy lint for issue 93883 (https://github.com/rust-lang/rust/issues/93883). Relies on a new trait in `marker` (called `SignificantDrop` to enable linting), which is why this PR is for the rust-lang repo and not the clippy repo.
changelog: new lint [`significant_drop_in_scrutinee`]
With #93803 `impl Trait` function arguments get desugared to hidden
where bounds. However, Clippy needs to know if a bound was originally a
impl Trait or an actual bound. This adds a field to the
`WhereBoundPredicate` struct to keep track of this information during
HIR lowering.
Address `unnecessary_to_owned` false positive
My proposed fix for #8759 is to revise the conditions that delineate `redundant_clone` and `unnecessary_to_owned`:
```rust
// Only flag cases satisfying at least one of the following three conditions:
// * the referent and receiver types are distinct
// * the referent/receiver type is a copyable array
// * the method is `Cow::into_owned`
// This restriction is to ensure there is no overlap between `redundant_clone` and this
// lint. It also avoids the following false positive:
// https://github.com/rust-lang/rust-clippy/issues/8759
// Arrays are a bit of a corner case. Non-copyable arrays are handled by
// `redundant_clone`, but copyable arrays are not.
```
This change causes a few cases that were previously flagged by `unnecessary_to_owned` to no longer be flagged. But one could argue those cases would be better handled by `redundant_clone`.
Closes#8759
changelog: none
Support negative ints in manual_range_contains
fixes: #8721
changelog: Fixes issue where ranges containing ints with different signs would be
incorrect due to comparing as unsigned.
Fix `cast_lossless` to avoid warning on `usize` to `f64` conversion.
Previously, the `cast_lossless` lint would issue a warning on code that
converted a `usize` value to `f64`, on 32-bit targets.
`usize` to `f64` is a lossless cast on 32-bit targets, however there is
no corresponding `f64::from` that takes a `usize`, so `cast_lossless`'s
suggested replacement does not compile.
This PR disables the lint in the case of casting from `usize` or `isize`.
Fixes#3689.
changelog: [`cast_lossless`] no longer gives wrong suggestion on usize,isize->f64
Lint `empty_lint_after_outer_attr` on argumentless macros
Reverts the change from 034c81b761 as it's no longer needed. The test is left just in case. Original issue is #2475.
changelog: Lint `empty_lint_after_outer_attr` on argumentless macros again
Those lints are trait_duplication_in_bounds and
type_repetition_in_bounds. I don't think those can be fixed on the
Clippy side alone, but need changes in the compiler. So let's move them
to nursery to get the sync through and then fix them on the rustc side.
Also adds a regression test that has to be fixed before they can be
moved back to pedantic.
Easier readability for `needless_late_init` message
Closes#8530
Updated the lint to use a `MultiSpan`, showing where the `let` statement was first used and where the initialisation statement was done, as in the format described, for easier readability.
Was wondering why, when pushing the span label for the initialisation statement, that sometimes the prior statement above the initialisation statement gets pulled into the output as well - any insight is appreciated!
---
changelog: [`needless_late_init`]: Now shows the `let` statement where it was first initialized
[FP] identity_op in front of if
fix#8724
changelog: FP: [`identity_op`]: is now allowed in front of if statements, blocks and other expressions where the suggestion would be invalid.
Resolved simular problems with blocks, mathces, and loops.
identity_op always does NOT suggest reducing `0 + if b { 1 } else { 2 } + 3` into `if b { 1 } else { 2 } + 3` even in the case that the expression is in `f(expr)` or `let x = expr;` for now.
Previously, the `cast_lossless` lint would issue a warning on code that
converted a `usize` value to `f64`, on 32-bit targets.
`usize` to `f64` is a lossless cast on 32-bit targets, however there is
no corresponding `f64::from` that takes a `usize`, so `cast_lossless`'s
suggested replacement does not compile.
This PR disables the lint in the case of casting from `usize` or `isize`.
Fixes#3689.
changelog: [`cast_lossless`] no longer gives wrong suggestion on usize->f64
Only crate root def-ids don't have a parent, and in majority of cases the argument of `DefIdTree::parent` cannot be a crate root.
So we now panic by default in `parent` and introduce a new non-panicing function `opt_parent` for cases where the argument can be a crate root.
Same applies to `local_parent`/`opt_local_parent`.
Change `span_suggestion` (and variants) to take `impl ToString` rather
than `String` for the suggested code, as this simplifies the
requirements on the diagnostic derive.
Signed-off-by: David Wood <david.wood@huawei.com>
ignore `redundant_pub_crate` in `useless_attribute`
changelog: [`useless_attribute`] no longer lints [`redundant_pub_crate`]
As mentioned in https://github.com/rust-lang/rust-clippy/issues/8732#issuecomment-1106489634
> And it turns out I can't even explicitly allow it at the usage site, because then `clippy::useless_attribute` fires (which would also be a FP?), which is deny-by-default.
>
> Though it does work if I then allow `clippy::useless_attribute`. 😂
>
> ```rust
> #[allow(clippy::useless_attribute)]
> #[allow(clippy::redundant_pub_crate)]
> pub(crate) use bit;
> ```
>
> The originally-reported warning now no longer occurs.
`needless_late_init`: ignore `if let`, `let mut` and significant drops
No longer lints `if let`, personal taste on this one is pretty split, so it probably shouldn't be warning by default. Fixes#8613
```rust
let x = if let Some(n) = y {
n
} else {
1
}
```
No longer lints `let mut`, things like the following are not uncommon and look fine as they are
b169c16d86/src/sixty_four.rs (L88-L93)
Avoids changing the drop order in an observable way, where the type of `x` has a drop with side effects and something between `x` and the first use also does, e.g.
48cc6cb791/tests/test_api.rs (L159-L167)
The implementation of `type_needs_ordered_drop_inner` was changed a bit, it now uses `Ty::has_significant_drop` and reordered the ifs to check diagnostic name before checking the implicit drop impl
changelog: [`needless_late_init`]: No longer lints `if let` statements, `let mut` bindings and no longer significantly changes drop order
mistyped_literal_suffix: improve integer suggestions, avoid wrong float suggestions
This PR fixes 2 things:
- The known problem that integer types are always suggested as signed, by suggesting an unsigned suffix for literals that wouldnt fit in the signed type, and ignores any literals too big for the corresponding unsigned type too.
- The lint would only look at the integer part of any floating point literals without an exponent, this causing #6129. This just ignores those literals.
Examples:
```rust
let _ = 2_32; // still 2_i32
let _ = 234_8; // would now suggest 234_u8
// these are now ignored
let _ = 500_8;
let _ = 123_32.123;
```
changelog: suggest correct integer types in [`mistyped_literal_suffix`], ignore float literals without an exponent
fixes#6129
Previously this lint would only look at the integer part of floating
point literals without an exponent, giving wrong suggestions like:
```
|
8 | let _ = 123_32.123;
| ^^^^^^^^^^ help: did you mean to write: `123.123_f32`
|
```
Instead, it now ignores these literals.
Fixes#6129
Instead of just always suggesting signed suffixes regardless of size
of the value, it now suggests an unsigned suffix when the value wouldn't
fit into the corresponding signed type, and ignores the literal entirely
if it is too big for the unsigned type as well.
wrong_self_convention allows `is_*` to take `&mut self`
fix#8480 and #8513
Allowing `is_*` to take `&self` or none is too restrictive.
changelog: FPs: [`wrong_self_convention`] now allows `&mut self` and no self as arguments for `is_*` methods
`manual_split_once`: lint manual iteration of `SplitN`
changelog: `manual_split_once`: lint manual iteration of `SplitN`
Now lints:
```rust
let mut iter = "a.b.c".splitn(2, '.');
let first = iter.next().unwrap();
let second = iter.next().unwrap();
let mut iter = "a.b.c".splitn(2, '.');
let first = iter.next()?;
let second = iter.next()?;
let mut iter = "a.b.c".rsplitn(2, '.');
let first = iter.next().unwrap();
let second = iter.next().unwrap();
let mut iter = "a.b.c".rsplitn(2, '.');
let first = iter.next()?;
let second = iter.next()?;
```
It suggests (minus leftover whitespace):
```rust
let (first, second) = "a.b.c".split_once('.').unwrap();
let (first, second) = "a.b.c".split_once('.')?;
let (second, first) = "a.b.c".rsplit_once('.').unwrap();
let (second, first) = "a.b.c".rsplit_once('.')?;
```
Currently only lints if the statements are next to each other, as detecting the various kinds of shadowing was tricky, so the following won't lint
```rust
let mut iter = "a.b.c".splitn(2, '.');
let something_else = 1;
let first = iter.next()?;
let second = iter.next()?;
```
Less authoritative stable_sort_primitive message
fixes#8241
Hey all - first contribution here so I'm deciding to start with something small.
Updated the linked message to be less authoritative as well as moved the lint grouping from `perf` to `pedantic` as suggested by `@camsteffen` under the issue.
changelog: [`stable_sort_primitive`]: emit less authoritative message and move to `pedantic`
