Add lint recommending using `std::iter::once` and `std::iter::empty`
```
changelog: [`iter_once`]: add new lint
changelog: [`iter_empty`]: add new lint
```
fixes#9186
- \[ ] Followed [lint naming conventions][lint_naming]
- \[x] Added passing UI tests (including committed `.stderr` file)
- \[x] `cargo test` passes locally
- \[x] Executed `cargo dev update_lints`
- \[x] Added lint documentation
- \[x] Run `cargo dev fmt`
[lint_naming]: https://rust-lang.github.io/rfcs/0344-conventions-galore.html#lints
The lint doesn't really follow the naming conventions. I don't have any better idea so I'm open to suggestions.
The expect_used lint is allow-by-default, so it would be better to show the case where this is enabled.
Co-authored-by: Takayuki Nakata <f.seasons017@gmail.com>
Add new lint `obfuscated_if_else`
part of #9100, additional commits could make it work with `then` and `unwrap_or_else` as well
changelog: Add new lint `obfuscated_if_else`
Improve lint doc consistency
changelog: none
This is a continuation of #8908.
Notable changes:
- Removed empty `Known Problems` sections
- Removed "Good"/"Bad" language (replaced with "Use instead")
- Removed (and added some 😄) duplication
- Ignored the [`create_dir`] example so it doesn't create `clippy_lints/foo` 😄
* Don't lint on `.cloned().flatten()` when `T::Item` doesn't implement `IntoIterator`
* Reduce verbosity of lint message
* Narrow down the scope of the replacement range
`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/`
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"
This adds test to make sure correct behavior of lint
- The first test's option variable is not a temporary variable
- The second test does not make usage of `take()`
- The third test makes usage of `take()` and uses a temporary variable
This lint checks if Option::take() is used on a temporary value (a value
that is not of type &mut Option and that is not a Place expression) to
suggest omitting take()
fix unnecessary_to_owned about msrv
This PR fixes ``[`unnecessary_owned`]``.
## What
```rust
# sample code
fn _msrv_1_35() {
#![clippy::msrv = "1.35"]
let _ = &["x"][..].to_vec().into_iter();
}
fn _msrv_1_36() {
#![clippy::msrv = "1.36"]
let _ = &["x"][..].to_vec().into_iter();
}
```
If we will check this code using clippy, ``[`unnecessary_owned`]`` will modify the code as follows.
```rust
error: unnecessary use of `to_vec`
--> $DIR/unnecessary_to_owned.rs:219:14
|
LL | let _ = &["x"][..].to_vec().into_iter();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use: `["x"][..].iter().copied()`
error: unnecessary use of `to_vec`
--> $DIR/unnecessary_to_owned.rs:224:14
|
LL | let _ = &["x"][..].to_vec().into_iter();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use: `["x"][..].iter().copied()`
```
This is incorrect. Because `Iterator::copied` was estabilished in 1.36.
## Why
This bug was caused by not separating "copied" and "clone" by reference to msrv.
89ee6aa6e3/clippy_lints/src/methods/unnecessary_to_owned.rs (L195)
So, I added a conditional branch and described the corresponding test.
Thank you in advance.
changelog: fix wrong suggestions about msrv in [`unnecessary_to_owned`]
r! `@giraffate`
