Split out `PredicatePolarity` from `ImplPolarity`
Because having to deal with a third `Reservation` level in all the trait solver code is kind of weird.
r? `@lcnr` or `@oli-obk`
Note that the caller chooses a type for type param
```
error[E0308]: mismatched types
--> $DIR/return-impl-trait.rs:23:5
|
LL | fn other_bounds<T>() -> T
| - -
| | |
| | expected `T` because of return type
| | help: consider using an impl return type: `impl Trait`
| expected this type parameter
...
LL | ()
| ^^ expected type parameter `T`, found `()`
|
= note: expected type parameter `T`
found unit type `()`
= note: the caller chooses the type of T which can be different from ()
```
Tried to see if "expected this type parameter" can be replaced, but that goes all the way to `rustc_infer` so seems not worth the effort and can affect other diagnostics.
Revives #112088 and #104755.
Do not warn on .map(_::clone) for Arc, Rc, and their weak variants
Those constructions are idiomatic, and using `Arc::clone(x)` and `Rc::clone(x)` is often the recommended way of cloning a `Arc` or a `Rc`.
Fix#12528
changelog: [`map_clone`]: do not warn on `.map(_::clone)` for `Arc`, `Rc`, and their `Weak` variants
Fix infinite loop in `cast_sign_loss` when peeling unwrap method calls
Fixes#12506
The lint wants to peel method calls but didn't actually reassign the expression, leading to an infinite loop.
----
changelog: Fix infinite loop in [`cast_sign_loss`] when having two chained `.unwrap()` calls
Mention `size_hint()` effect in `flat_map_option` lint documentation.
The previous documentation for `flat_map_option` mentioned only readability benefits, but there is also at least one performance benefit: the `size_hint()` upper bound is preserved, whereas `flat_map().size_hint()` is always `(0, None)`.
Program demonstrating this difference:
```rust
fn main() {
let evens = |i| if i % 2 == 0 { Some(i) } else { None };
dbg!(
[1, 2, 3].iter().flat_map(evens).size_hint(),
[1, 2, 3].iter().filter_map(evens).size_hint(),
);
}
```
changelog: [`flat_map_option`]: Mention the benefit to `size_hint()`.
Experimental feature postfix match
This has a basic experimental implementation for the RFC postfix match (rust-lang/rfcs#3295, #121618). [Liaison is](https://rust-lang.zulipchat.com/#narrow/stream/213817-t-lang/topic/Postfix.20Match.20Liaison/near/423301844) ```@scottmcm``` with the lang team's [experimental feature gate process](https://github.com/rust-lang/lang-team/blob/master/src/how_to/experiment.md).
This feature has had an RFC for a while, and there has been discussion on it for a while. It would probably be valuable to see it out in the field rather than continue discussing it. This feature also allows to see how popular postfix expressions like this are for the postfix macros RFC, as those will take more time to implement.
It is entirely implemented in the parser, so it should be relatively easy to remove if needed.
This PR is split in to 5 commits to ease review.
1. The implementation of the feature & gating.
2. Add a MatchKind field, fix uses, fix pretty.
3. Basic rustfmt impl, as rustfmt crashes upon seeing this syntax without a fix.
4. Add new MatchSource to HIR for Clippy & other HIR consumers
Several (doc) comments were super outdated or didn't provide enough context.
Some doc comments shoved everything in a single paragraph without respecting
the fact that the first paragraph should be a single sentence because rustdoc
treats these as item descriptions / synopses on module pages.
Fix documentation typo "appects" > "affects"
changelog: none
This fixes a typo in the `iter_filter_is_some` and `iter_filter_is_ok` lint documentation.
Add xFrednet back to the reviewing rotation 🎉
You know what? Having a work-life balance is boring.
I truly enjoyed having a free few weeks, and learned that I need to take a break every once in a while, but not doing reviews feels weird. So, this is me coming back for more :D
---
r? `@ghost`
changelog: none
Split an item bounds and an item's super predicates
This is the moral equivalent of #107614, but instead for predicates this applies to **item bounds**. This PR splits out the item bounds (i.e. *all* predicates that are assumed to hold for the alias) from the item *super predicates*, which are the subset of item bounds which share the same self type as the alias.
## Why?
Much like #107614, there are places in the compiler where we *only* care about super-predicates, and considering predicates that possibly don't have anything to do with the alias is problematic. This includes things like closure signature inference (which is at its core searching for `Self: Fn(..)` style bounds), but also lints like `#[must_use]`, error reporting for aliases, computing type outlives predicates.
Even in cases where considering all of the `item_bounds` doesn't lead to bugs, unnecessarily considering irrelevant bounds does lead to a regression (#121121) due to doing extra work in the solver.
## Example 1 - Trait Aliases
This is best explored via an example:
```
type TAIT<T> = impl TraitAlias<T>;
trait TraitAlias<T> = A + B where T: C;
```
The item bounds list for `Tait<T>` will include:
* `Tait<T>: A`
* `Tait<T>: B`
* `T: C`
While `item_super_predicates` query will include just the first two predicates.
Side-note: You may wonder why `T: C` is included in the item bounds for `TAIT`? This is because when we elaborate `TraitAlias<T>`, we will also elaborate all the predicates on the trait.
## Example 2 - Associated Type Bounds
```
type TAIT<T> = impl Iterator<Item: A>;
```
The `item_bounds` list for `TAIT<T>` will include:
* `Tait<T>: Iterator`
* `<Tait<T> as Iterator>::Item: A`
But the `item_super_predicates` will just include the first bound, since that's the only bound that is relevant to the *alias* itself.
## So what
This leads to some diagnostics duplication just like #107614, but none of it will be user-facing. We only see it in the UI test suite because we explicitly disable diagnostic deduplication.
Regarding naming, I went with `super_predicates` kind of arbitrarily; this can easily be changed, but I'd consider better names as long as we don't block this PR in perpetuity.
Changelog for Clippy 1.77 🏫
Roses are violets,
Red is blue,
Let's create a world,
Perfect for me and you
---
### The cat of this release is: *Luigi*
<img width=500 src="https://github.com/rust-lang/rust-clippy/assets/17087237/ea13d05c-e5ba-4189-9e16-49bf1b43c468" alt="The cats of this Clippy release" />
The cat for the next release can be voted on: [here](https://forms.gle/57gbrNvXtCUmrHYh6)
The cat for the next next release can be nominated in the comments and will be voted in the next changelog PR (Submission deadline is 2024-03-30 23:59CET)
---
changelog: none
Disable `cast_lossless` when casting to u128 from any (u)int type
Fixes https://github.com/rust-lang/rust-clippy/issues/12492
Disables `cast_lossless` when casting to u128 from any int or uint type. The lint states that when casting to any int type, there can potentially be lossy behaviour if the source type ever exceeds the size of the destination type in the future, which is impossible with a destination of u128.
It's possible this is a bit of a niche edge case which is better addressed by just disabling the lint in code, but I personally couldn't think of any good reason to still lint in this specific case - maybe except if the source is a bool, for readability reasons :).
changelog: FP: `cast_lossless`: disable lint when casting to u128 from any (u)int type
Make `assigning_clones` MSRV check more precise
Continuation of #12511
`clone_into` is the only suggestion subject to the 1.63 MSRV requirement, and the lint should still emit other suggestions regardless of the MSRV.
changelog: [assigning_clones]: only apply MSRV check to `clone_into` suggestions.
