Add `unnecessary_to_owned` lint
This PR adds a lint to check for unnecessary calls to `ToOwned::to_owned` and other similar functions (e.g., `Cow::into_owned`, `ToString::to_string`, etc.).
The lint checks for expressions of the form `&receiver.to_owned_like()` used in a position requiring type `&T` where one of the following is true:
* `receiver`'s type is `T` exactly
* `receiver`'s type implements `Deref<Target = T>`
* `receiver`'s type implements `AsRef<T>`
The lint additionally checks for expressions of the form `receiver.to_owned_like()` used as arguments of type `impl AsRef<T>`.
It would be nice if the lint could also check for expressions used as arguments to functions like the following:
```
fn foo<T: AsRef<str>>(x: T) { ... }
```
However, I couldn't figure out how to determine whether a function input type was instantiated from a parameter with a trait bound.
If someone could offer me some guidance, I would be happy to add such functionality.
Closes#7933
changelog: Add [`unnecessary_to_owned`] lint
Constify `bool::then{,_some}`
Note on `~const Drop`: it has no effect when called from runtime functions, when called from const contexts, the trait system ensures that the type can be dropped in const contexts.
Make `TyS::is_suggestable` check for non-suggestable types structually
Not sure if I went overboard checking substs in dyn types, etc. Let me know if I should simplify this function.
Fixes#91832
Remove `in_band_lifetimes` from `rustc_codegen_ssa`
See #91867 for more information.
In `compiler/rustc_codegen_ssa/src/coverageinfo/map.rs`, there are several functions with an explicit `'a` lifetime but only a single `&'a self` parameter. These lifetimes should be redundant given lifetime elision, unless the existential `impl Iterator` has weird issues regarding that. Should the redundant lifetimes be removed?
Removed `in_band_lifetimes` from `library\proc_macro`
Issue [#91867](https://github.com/rust-lang/rust/issues/91867)
This is my first try, I followed the instructions given. Fixed all the errors that were thrown while compiling.
Compiled with stage 0,1, and 2 all of them compiled successfully.
Handle unordered const/ty generics for object lifetime defaults
*feel like I should have a PR description but cant think of what to put here*
r? ```@lcnr```
Add `[T]::as_simd(_mut)`
SIMD-style optimizations are the most common use for `[T]::align_to(_mut)`, but that's `unsafe`. So these are *safe* wrappers around it, now that we have the `Simd` type available, to make it easier to use.
```rust
impl [T] {
pub fn as_simd<const LANES: usize>(&self) -> (&[T], &[Simd<T, LANES>], &[T]);
pub fn as_simd_mut<const LANES: usize>(&mut self) -> (&mut [T], &mut [Simd<T, LANES>], &mut [T]);
}
```
They're `cfg`'d out for miri because the `simd` module as a whole is unavailable there.
Readd track_caller to Result::from_residual
This is a followup on https://github.com/rust-lang/rust/issues/87401 in and an attempt to move the issue towards resolution.
As part of the overhaul of the Try trait we removed the ability for errors to grab location information during propagation via `?` with the builtin `std::result::Result`. The previously linked issue has a fair bit of discussion into the reasons for and against the usage of `#[track_caller]` on the `FromResidual` impl on `Result` that I will do my best to summarize.
---
### For
- https://github.com/rust-lang/rust/issues/87401#issuecomment-915053533: Difficulties with using non `std::result::Result` like types
- https://github.com/rust-lang/rust/issues/87401#issuecomment-978355102: Inconsistency with functionality provided for recoverable (Result) and non-recoverable errors (panic), where panic provides a location and Result does not, pushing some users towards using panic
### Against
- https://github.com/rust-lang/rust/issues/84277#issuecomment-885322833: concern that this will bloat callers that never use this data
---
Personally, I want to quantify the performance / bloat impact of re-adding this attribute, and fully evaluate the pros and cons before deciding if I need to switch `eyre` to have a custom `Result` type, which would also mean I need `try_trait_v2` to be stabilized, cc `@scottmcm.` If the performance impact is minor enough in the general case I think I would prefer that the default `Result` type has the ability to track location information for consistency with `panic` error reporting, and leave it to applications that need particularly high performance to handle the micro optimizations of introducing their own efficient custom Result type or matching manually.
Alternatively, I wonder if the performance penalty on code that doesn't use the location information on `FromResidual` could be mitigated via new optimizations.
By changing `as_str()` to take `&self` instead of `self`, we can just
return `&str`. We're still lying about lifetimes, but it's a smaller lie
than before, where `SymbolStr` contained a (fake) `&'static str`!
Stabilize `iter::zip`
Hello all!
As the tracking issue (#83574) for `iter::zip` completed the final commenting period without any concerns being raised, I hereby submit this stabilization PR on the issue.
As the pull request that introduced the feature (#82917) states, the `iter::zip` function is a shorter way to zip two iterators. As it's generally a quality-of-life/ergonomic improvement, it has been integrated into the codebase without any trouble, and has been
used in many places across the rust compiler and standard library since March without any issues.
For more details, I would refer to `@cuviper's` original PR, or the [function's documentation](https://doc.rust-lang.org/std/iter/fn.zip.html).
Stabilize `iter::zip`
Hello all!
As the tracking issue (#83574) for `iter::zip` completed the final commenting period without any concerns being raised, I hereby submit this stabilization PR on the issue.
As the pull request that introduced the feature (#82917) states, the `iter::zip` function is a shorter way to zip two iterators. As it's generally a quality-of-life/ergonomic improvement, it has been integrated into the codebase without any trouble, and has been
used in many places across the rust compiler and standard library since March without any issues.
For more details, I would refer to `@cuviper's` original PR, or the [function's documentation](https://doc.rust-lang.org/std/iter/fn.zip.html).
Revert setting a default for the MACOSX_DEPLOYMENT_TARGET env var for linking
This reverts commit b376f5621b, which is the main part of #90499, because it turns out that this causes a good amount of breakage in crates relying on the old behavior. In particular `winit`, `coreaudio` and crates that depend on them are affected. Fixes#91372.
Background:
Before #90499 the behavior was the following: If MACOSX_DEPLOYMENT_TARGET is not set, we pass the minimum supported OS version to LLVM but not to the linker. The linker default depends on the Xcode version and the version of the OS it is running on. That caused one known problem in libcurl with the most recent Xcode versions. #90499 passed the minumum supported version (10.7 for Macos x86-64) to the linker instead. This has shown to be problematic because some crates such as winit, coreaudio implicitly expect a newer minimum OS version. The libcurl issue has been fixed independently (see https://github.com/alexcrichton/curl-rust/issues/417), so a revert should not really be problematic.
Eventually we should probably mimic clang's behavior and fall back to the default of the currently configured Macos SDK for both the LLVM min os target version and MACOSX_DEPLOYMENT_TARGET for linking. That would entail looking at the `Version` property of the `SDKSettings.json` in the currently configured SDK.
Use `OutputFilenames` to generate output file for `-Zllvm-time-trace`
The resulting profile will include the crate name and will be stored in
the `--out-dir` directory.
This implementation makes it convenient to use LLVM time trace together
with cargo, in the contrast to the previous implementation which would
overwrite profiles or store them in `.cargo/registry/..`.
Tweak errors coming from `for`-loop, `?` and `.await` desugaring
* Suggest removal of `.await` on non-`Future` expression
* Keep track of obligations introduced by desugaring
* Remove span pointing at method for obligation errors coming from desugaring
* Point at called local sync `fn` and suggest making it `async`
```
error[E0277]: `()` is not a future
--> $DIR/unnecessary-await.rs:9:10
|
LL | boo().await;
| -----^^^^^^ `()` is not a future
| |
| this call returns `()`
|
= help: the trait `Future` is not implemented for `()`
help: do not `.await` the expression
|
LL - boo().await;
LL + boo();
|
help: alternatively, consider making `fn boo` asynchronous
|
LL | async fn boo () {}
| +++++
```
Fix#66731.
Tweak errors coming from `for`-loop, `?` and `.await` desugaring
* Suggest removal of `.await` on non-`Future` expression
* Keep track of obligations introduced by desugaring
* Remove span pointing at method for obligation errors coming from desugaring
* Point at called local sync `fn` and suggest making it `async`
```
error[E0277]: `()` is not a future
--> $DIR/unnecessary-await.rs:9:10
|
LL | boo().await;
| -----^^^^^^ `()` is not a future
| |
| this call returns `()`
|
= help: the trait `Future` is not implemented for `()`
help: do not `.await` the expression
|
LL - boo().await;
LL + boo();
|
help: alternatively, consider making `fn boo` asynchronous
|
LL | async fn boo () {}
| +++++
```
Fix#66731.
