Implemented `suspicious_to_owned` lint to check if `to_owned` is called on a `Cow`
changelog: Add lint ``[`suspicious_to_owned`]``
-----------------
Hi,
posting this unsolicited PR as I've been burned by this issue :)
Being unsolicited, feel free to reject it or reassign a different lint level etc.
This lint checks whether `to_owned` is called on `Cow<'_, _>`. This is done because `to_owned` is very similarly named to `into_owned`, but the effect of calling those two methods is completely different (one makes the `Cow::Borrowed` into a `Cow::Owned`, the other just clones the `Cow`). If the cow is then passed to code for which the type is not checked (e.g. generics, closures, etc.) it might slip through and if the cow data is coming from an unsafe context there is the potential for accidentally cause undefined behavior.
Even if not falling into this painful case, there's really no reason to call `to_owned` on a `Cow` other than confusing people reading the code: either `into_owned` or `clone` should be called.
Note that this overlaps perfectly with `implicit_clone` as a warning, but `implicit_clone` is classified pedantic (while the consequences for `Cow` might be of a wider blast radius than just pedantry); given the overlap, I set-up the lint so that if `suspicious_to_owned` triggers `implicit_clone` will not trigger. I'm not 100% sure this is done in the correct way (I tried to copy what other lints were doing) so please provide feedback on it if it isn't.
### Checklist
- \[x] 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`
It's a common phenomenon that feature stabilizations don't make it into
a particular release, but the version is still inaccurate. Often this
leads to subsequent changes to adjust/correct the version.
Instead, require people to put a placeholder that gets replaced during
beta branching time with the current rust version. That way, there is
no chance that an error can be introduced.
Usage of the placeholder is required on the nightly channel, and forbidden
on the stable and beta channels.
Simplify the arguments to macros generated by the `rustc_queries` proc macro
Very small cleanup. Based on https://github.com/rust-lang/rust/pull/100436 which modifies some of the same code.
r? `@cjgillot`
Don't lint `needless_return` if `return` has attrs
Fixes#9361
The lint used to have a mechanic to allow `cfg`-attrs on naked `return`-statements. This was well-intentioned, yet we can have any kind of attribute, e.g. `allow`, `expect` or even custom `derive`. So the mechanic was simply removed. We now never lint on a naked `return`-statement that has attributes on it.
Turns out that the ui-test had a Catch22 in it: In `check_expect()` the `#[expect(clippy::needless_return)]` is an attribute on the `return` statement that can and will be rustfixed away without side effects. But any other attribute would also have been removed, which is what #9361 is about. The test proved the wrong thing. Removed the test, the body is tested elsewhere as well.
changelog: Ignore [`needless_return`] on `return`s with attrs
Merge duplicated CSS rules
I used the [stylelint](https://stylelint.io/user-guide/configure) tool to check for duplicated CSS rules in order to merge them.
r? `@notriddle`
rustdoc: remove incorrect CSS selector `.impl-items table td`
Fixes#100994
This selector was added in c7312fbae4. The bug can be seen at <https://doc.rust-lang.org/1.27.0/alloc/slice/trait.SliceIndex.html#foreign-impls>.
This rule was added to help with a `<table>` that was used for displaying the function signature [src] lockup. That lockup was changed in 34bd2b845b to use flexbox instead, leaving this selector unused (at least, for its original purpose).
rustdoc: remove unused CSS for `hidden-by-*-hider`
This CSS seems to have become obsolete with the move to `<details>` tags,
and its corresponding JavaScript was removed in aee054d05d
rustdoc: omit start/end tags for empty item description blocks
Related to #100952
This is definitely not a complete solution, but it does shrink keysyms/index.html on smithay from 620K to 516K.
Update documentation for `write!` and `writeln!`
https://github.com/rust-lang/rust/pull/37472 added this documentation, but it
needs updating:
- Remove some documentation duplicated between `writeln!` and `write!`
- Update `write!` docs: can now import traits as `_` to avoid conflicts
- Expand example to show how to implement qualified trait names
Fix wrong compiletest filters on Windows
As discussed in [#79334](https://github.com/rust-lang/rust/issues/79334), when calling e.g.
```
python x.py test src/test/ui/expr/compound-assignment/eval-order.rs
```
on Windows, compiletest passes the filter `expr/compound-assignment/eval-order.rs` to libtest, which instead should be `expr\compound-assignment\eval-order.rs`, as that is the file found when collecting tests. This is what I fixed.
I'm not sure how to organize a test for this. Any suggestions?
Make forward compatibility lint deprecated_cfg_attr_crate_type_name deny by default
Turns the forward compatibility lint added by #83744 to deprecate `cfg_attr` usage with `#![crate_type]` and `#![crate_name]` attributes into deny by default. Copying the example from #83744:
```Rust
#![crate_type = "lib"] // remains working
#![cfg_attr(foo, crate_type = "bin")] // will stop working
```
Over 8 months have passed since #83744 was merged so I'd say this gives ample time for people to have been warned, so we can make the warning stronger. No usage was found via grep.app except for one, which was in an unmaintained code base that didn't seem to be used in the open source eco system. The crater run conducted in #83744 also didn't show up anything.
cc #91632 - tracking issue for the lint
