Merged
Conversation
std: implement the `once_wait` feature Tracking issue: rust-lang#127527 This additionally adds a `wait_force` method to `Once` that doesn't panic on poison. I also took the opportunity and cleaned up up the code of the queue-based implementation a bit.
Cleanup sys module to match house style This moves a test file out of sys as it's just testing std types. Also cleans up some assorted bits including making the `use` statements match the house style.
Update target-spec metadata for loongarch64 targets
… r=fmease
Properly mark loop as diverging if it has no breaks
Due to specifics about the desugaring of the `.await` operator, HIR typeck doesn't recognize that `.await`ing an `impl Future<Output = !>` will diverge in the same way as calling a `fn() -> !`.
This is because the await operator desugars to approximately:
```rust
loop {
match future.poll(...) {
Poll::Ready(x) => break x,
Poll::Pending => {}
}
}
```
We know that the value of `x` is `!`, however since `break` is a coercion site, we coerce `!` to some `?0` (the type of the loop expression). Then since the type of the `loop {...}` expression is `?0`, we will not detect the loop as diverging like we do with other expressions that evaluate to `!`:
https://github.com/rust-lang/rust/blob/0b5eb7ba7bd796fb39c8bb6acd9ef6c140f28b65/compiler/rustc_hir_typeck/src/expr.rs#L240-L243
We can technically fix this in two ways:
1. Make coercion of loop exprs more eagerly result in a type of `!` when the only break expressions have type `!`.
2. Make loops understand that all of that if they have only diverging break values, then the loop diverges as well.
(1.) likely has negative effects on inference, and seems like a weird special case to drill into coercion. However, it turns out that (2.) is very easy to implement, we already record whether a loop has any break expressions, and when we do so, we actually skip over any break expressions with diverging values!:
https://github.com/rust-lang/rust/blob/0b5eb7ba7bd796fb39c8bb6acd9ef6c140f28b65/compiler/rustc_hir_typeck/src/expr.rs#L713-L716
Thus, we can consider the loop as diverging if we see that it has no breaks, which is the change implemented in this PR.
This is not usually a problem in regular code for two reasons:
1. In regular code, we already mark `break diverging()` as unreachable if `diverging()` is unreachable. We don't do this for `.await`, since we suppress unreachable errors within `.await` (rust-lang#64930). Un-suppressing this code will result in spurious unreachable expression errors pointing to internal await machinery.
3. In loops that truly have no breaks (e.g. `loop {}`), we already evaluate the type of the loop to `!`, so this special case is kinda moot. This only affects loops that have `break`s with values of type `!`.
Thus, this seems like a change that may affect more code than just `.await`, but it likely does not in meaningful ways; if it does, it's certainly correct to apply.
Fixes rust-lang#128434
… r=compiler-errors Temporarily switch `ambiguous_negative_literals` lint to allow This PR temporarily switch the `ambiguous_negative_literals` lint to `allow-by-default`, as asked by T-lang in rust-lang#128287 (comment).
…-maybe-sized, r=compiler-errors derive(SmartPointer): require pointee to be maybe sized cc ``@Darksonn`` So `#[pointee]` has to be `?Sized` in order for deriving `SmartPointer` to be meaningful. cc ``@compiler-errors`` for suggestions in rust-lang#127681
rustbot
added
O-windows
Member
Author
|
@bors r+ rollup=never p=6 |
Collaborator
bors
added
S-waiting-on-bors
Collaborator
Collaborator
|
☀️ Test successful - checks-actions |
Collaborator
|
📌 Perf builds for each rolled up PR:
previous master: 28a58f2fa7 In the case of a perf regression, run the following command for each PR you suspect might be the cause: |
Collaborator
|
Finished benchmarking commit (71b2116): comparison URL. Overall result: ❌ regressions - ACTION NEEDEDNext Steps: If you can justify the regressions found in this perf run, please indicate this with @rustbot label: +perf-regression Instruction countThis is a highly reliable metric that was used to determine the overall result at the top of this comment.
Max RSS (memory usage)Results (primary 6.3%, secondary 3.1%)This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.
CyclesResults (secondary 6.1%)This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.
Binary sizeResults (primary -0.1%, secondary 0.0%)This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.
Bootstrap: 757.595s -> 758.318s (0.10%) |
Member
rustbot
added
the
perf-regression-triaged
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
11 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Successful merges:
once_waitfeature #127567 (std: implement theonce_waitfeature)ambiguous_negative_literalslint to allow #128449 (Temporarily switchambiguous_negative_literalslint to allow)r? @ghost
@rustbot modify labels: rollup
Create a similar rollup