Don't lint `multiple_inherent_impl` with generic arguments
fixes: #5772
changelog: Treat different generic arguments as different types in `multiple_inherent_impl`
Remove powi, "square can be computed more efficiently"
powi(2) produces exactly the same native code as x * x
powi was part of the [`suboptimal_flops`] lint
fixes#7058
changelog: Remove powi [`suboptimal_flops`], "square can be computed more efficiently"
Add `needless_bitwise_bool` lint
fixes#6827fixes#1594
changelog: Add ``[`needless_bitwise_bool`]`` lint
Creates a new `bitwise_bool` lint to convert `x & y` to `x && y` when both `x` and `y` are booleans. I also had to adjust thh `needless_bool` lint slightly, and fix a couple failing dogfood tests. I made it a correctness lint as per flip1995's comment [here](https://github.com/rust-lang/rust-clippy/pull/3385#issuecomment-434715723), from a previous WIP attempt at this lint.
Fix FPs about generic args
Fix 2 false positives in [`use_self`] and [`useless_conversion`] lints, by taking into account generic args and comparing them.
Fixes: #7205Fixes: #7206
changelog: Fix FPs about generic args in [`use_self`] and [`useless_conversion`] lints
New lint: `unused_async`
changelog: Adds a lint, `unused_async`, which checks for async functions with no await statements
`unused_async` is a lint that reduces code smell and overhead by encouraging async functions to be refactored into synchronous functions.
Fixes#7176
### Examples
```rust
async fn get_random_number() -> i64 {
4 // Chosen by fair dice roll. Guaranteed to be random.
}
```
Could be written as:
```rust
fn get_random_number() -> i64 {
4 // Chosen by fair dice roll. Guaranteed to be random.
}
```
Something like this, however, should **not** be caught by clippy:
```rust
#[async_trait]
trait AsyncTrait {
async fn foo();
}
struct Bar;
#[async_trait]
impl AsyncTrait for Bar {
async fn foo() {
println!("bar");
}
}
```
Stop linting `else if let` pattern in [`option_if_let_else`] lint
For readability concerns, it is counterproductive to lint `else if let` pattern.
Unfortunately the suggested code is much less readable.
Fixes: #7006
changelog: stop linting `else if let` pattern in [`option_if_let_else`] lint
Add `cargo collect-metadata` as an cargo alias for the metadata collection lint
This PR adds a new alias to run the metadata collection monster on `clippy_lints`. I'm currently using it to create the `metadata_collection.json` file and I plan to use it in the `deply.sh` script. Having it as a new alias enables us to simply use:
```sh
cargo collect-metadata
```
It sometimes requires running `cargo clean` before collecting the metadata due to caching. I'm still debating if I should include a cargo clean as part of the `run_metadata_collection_lint` test or not. Input on this would be greatly appreciated 🙃
That's it, just a small change that can be reviewed and merged in parallel to #7214.
---
See: #7172 for the full metadata collection to-do list or to suggest a new feature in connection to it.
---
changelog: none
r? `@flip1995` btw. feel free to pass these PRs one to other team members as well if you want.
`needless_collect` enhancements
fixes#7164
changelog: `needless_collect`: For `BTreeMap` and `HashMap` lint only `is_empty`, as `len` might produce different results than iter's `count`
changelog: `needless_collect`: Lint `LinkedList` and `BinaryHeap` in direct usage case as well
Trigger [`wrong_self_convention`] only if it has implicit self
Lint [`wrong_self_convention`] only if the impl or trait has `self` _per sé_.
Fixes: #7179
changelog: trigger [`wrong_self_convention`] only if it has implicit self
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.
* Suggest `&mut iter` when the iterator is used after the loop.
* Suggest `&mut iter` when the iterator is a field in a struct.
* Don't lint when the iterator is a field in a struct, and the struct is
used in the loop.
* Lint when the loop is nested in another loop, but suggest `&mut iter`
unless the iterator is from a local declared inside the loop.
Fix needless_quesiton_mark false positive
changelog: Fix [`needless_question_mark`] false positive where the inner value is implicity dereferenced by the question mark.
Fixes#7107
Handle write!(buf, "\n") case better
Make `write!(buf, "\n")` suggest `writeln!(buf)` by removing
the trailing comma from `writeln!(buf, )`.
changelog: [`write_with_newline`] suggestion on only "\n" improved
Make `write!(buf, "\n")` suggest `writeln!(buf)` by removing
the trailing comma from `writeln!(buf, )`.
changelog: [`write_with_newline`] suggestion on only "\n" improved
It relaxes rules for `to_*` variant, so it doesn't lint in trait definitions
and implementations anymore.
Although, non-`Copy` type implementing trait's `to_*` method taking
`self` feels not good (consumes ownership, so should be rather named `into_`), it would be better if this case was a pedantic lint (allow-by-default) instead.
Refactor: arrange lints in misc_early module
This PR arranges misc_early lints so that they can be accessed more easily.
Basically, I refactored them following the instruction described in #6680.
cc: `@Y-Nak,` `@flip1995,` `@magurotuna`
changelog: Move lints in misc_early module into their own modules.
