Rollup of 3 pull requests
Successful merges:
- #126140 (Rename `std::fs::try_exists` to `std::fs::exists` and stabilize fs_try_exists)
- #126318 (Add a `x perf` command for integrating bootstrap with `rustc-perf`)
- #126552 (Remove use of const traits (and `feature(effects)`) from stdlib)
r? `@ghost`
`@rustbot` modify labels: rollup
Remove use of const traits (and `feature(effects)`) from stdlib
The current uses are already unsound because they are using non-const impls in const contexts. We can reintroduce them by reverting the commit in this PR, after #120639 lands.
Also, make `effects` an incomplete feature.
cc `@rust-lang/project-const-traits`
r? `@compiler-errors`
Generalize `{Rc,Arc}::make_mut()` to unsized types.
* `{Rc,Arc}::make_mut()` now accept any type implementing the new unstable trait `core::clone::CloneToUninit`.
* `CloneToUninit` is implemented for `T: Clone` and for `[T] where T: Clone`.
* `CloneToUninit` is a generalization of the existing internal trait `alloc::alloc::WriteCloneIntoRaw`.
* New feature gate: `clone_to_uninit`
This allows performing `make_mut()` on `Rc<[T]>` and `Arc<[T]>`, which was not previously possible.
---
Previous PR description, now obsolete:
> Add `{Rc, Arc}::make_mut_slice()`
>
> These functions behave identically to `make_mut()`, but operate on `Arc<[T]>` instead of `Arc<T>`.
>
> This allows performing the operation on slices, which was not previously possible because `make_mut()` requires `T: Clone` (and slices, being `!Sized`, do not and currently cannot implement `Clone`).
>
> Feature gate: `make_mut_slice`
try-job: test-various
This requires introducing a new internal type `RcUninit` (and
`ArcUninit`), which can own an `RcBox<T>` without requiring it to be
initialized, sized, or a slice. This is similar to `UniqueRc`, but
`UniqueRc` doesn't support the allocator parameter, and there is no
`UniqueArc`.
This trait allows cloning DSTs, but is unsafe to implement and use
because it writes to possibly-uninitialized memory which must be of the
correct size, and must initialize that memory.
It is only implemented for `T: Clone` and `[T] where T: Clone`, but
additional implementations could be provided for specific `dyn Trait`
or custom-DST types.
Stop using `unlikely` in `strict_*` methods
The `strict_*` methods don't need (un)likely, because the `overflow_panic` calls are all `#[cold]`, [meaning](https://llvm.org/docs/LangRef.html#function-attributes) that LLVM knows any branch to them is unlikely without us needing to say so.
r? libs
Add PidFd::{kill, wait, try_wait}
#117957 changed `Child` kill/wait/try_wait to use its pidfd instead of the pid, when one is available.
This PR extracts those implementations and makes them available on `PidFd` directly.
The `PidFd` implementations differ significantly from the corresponding `Child` methods:
* the methods can be called after the child has been reaped, which will result in an error but will be safe. This state is not observable in `Child` unless something stole the zombie child
* the `ExitStatus` is not kept, meaning that only the first time a wait succeeds it will be returned
* `wait` does not close stdin
* `wait` only requires `&self` instead of `&mut self` since there is no state to maintain and subsequent calls are safe
Tracking issue: #82971
As long as a pidfd is on a child it can be safely reaped. Taking it
would mean the child would now have to be awaited through its pid, but could also
be awaited through the pidfd. This could then suffer from a recycling race.
Rollup of 8 pull requests
Successful merges:
- #126125 (Improve conflict marker recovery)
- #126481 (Add `powerpc-unknown-openbsd` maintenance status)
- #126613 (Print the tested value in int_log tests)
- #126617 (Expand `avx512_target_feature` to include VEX variants)
- #126700 (Make edition dependent `:expr` macro fragment act like the edition-dependent `:pat` fragment does)
- #126707 (Pass target to inaccessible-temp-dir rmake test)
- #126767 (`StaticForeignItem` and `StaticItem` are the same)
- #126774 (Fix another assertion failure for some Expect diagnostics.)
r? `@ghost`
`@rustbot` modify labels: rollup
Print the tested value in int_log tests
Tiny change - from the failures in https://github.com/rust-lang/rust/pull/125016, it would have been nice to see what the tested values were. Update the assertion messages.
It's unnecessary when that arm leads to a `#[cold]` panic anyway, since controlling branch likihood is what `#[cold]` is all about.
(And, well, it's unclear whether `unlikely!` even works these days anyway.)
Account for things that optimize out in inlining costs
This updates the MIR inlining `CostChecker` to have both bonuses and penalties, rather than just penalties.
That lets us add bonuses for some things where we want to encourage inlining without risking wrapping into a gigantic cost. For example, `switchInt(const …)` we give an inlining bonus because codegen will actually eliminate the branch (and associated dead blocks) once it's monomorphized, so measuring both sides of the branch gives an unrealistically-high cost to it. Similarly, an `unreachable` terminator gets a small bonus, because whatever branch leads there doesn't actually exist post-codegen.
Replace sort implementations
This PR replaces the sort implementations with tailor-made ones that strike a balance of run-time, compile-time and binary-size, yielding run-time and compile-time improvements. Regressing binary-size for `slice::sort` while improving it for `slice::sort_unstable`. All while upholding the existing soft and hard safety guarantees, and even extending the soft guarantees, detecting strict weak ordering violations with a high chance and reporting it to users via a panic.
* `slice::sort` -> driftsort [design document](https://github.com/Voultapher/sort-research-rs/blob/main/writeup/driftsort_introduction/text.md), includes detailed benchmarks and analysis.
* `slice::sort_unstable` -> ipnsort [design document](https://github.com/Voultapher/sort-research-rs/blob/main/writeup/ipnsort_introduction/text.md), includes detailed benchmarks and analysis.
#### Why should we change the sort implementations?
In the [2023 Rust survey](https://blog.rust-lang.org/2024/02/19/2023-Rust-Annual-Survey-2023-results.html#challenges), one of the questions was: "In your opinion, how should work on the following aspects of Rust be prioritized?". The second place was "Runtime performance" and the third one "Compile Times". This PR aims to improve both.
#### Why is this one big PR and not multiple?
* The current documentation gives performance recommendations for `slice::sort` and `slice::sort_unstable`. If for example only one of them were to be changed, this advice would be misleading for some Rust versions. By replacing them atomically, the advice remains largely unchanged, and users don't have to change their code.
* driftsort and ipnsort share a substantial part of their implementations.
* The implementation of `select_nth_unstable` uses internals of `slice::sort_unstable`, which makes it impractical to split changes.
---
This PR is a collaboration with `@orlp.`
Remove `feature(const_closures)` from libcore
This is an incomplete feature and apparently it has no uses in `core`. Incomplete features should generally not be used in our standard library.
Clean up some comments near `use` declarations
#125443 will reformat all `use` declarations in the repository. There are a few edge cases involving comments on `use` declarations that require care. This PR cleans up some clumsy comment cases, taking us a step closer to #125443 being able to merge.
r? ``@lqd``
Make Option::as_[mut_]slice const
These two functions can both be made `const`. I have added them to the `const_option_ext` feature, #91930. I don't believe there is anything blocking stabilization of `as_slice`, but `as_mut_slice` contains mutable references so depends on `const_mut_refs`.
Stabilise `c_unwind`
Fix#74990Fix#115285 (that's also where FCP is happening)
Marking as draft PR for now due to `compiler_builtins` issues
r? `@Amanieu`
reword the hint::blackbox non-guarantees
People were tripped up by the "precludes", interpreting it that this function must not ever be used in cryptographic contexts rather than the std lib merely making zero promises about it being fit-for-purpose.
What remains unchanged is that if someone does try to use it *despite the warnings* then it is on them to pin their compiler versions and verify the assembly of every single binary build they do.
Most modules have such a blank line, but some don't. Inserting the blank
line makes it clearer that the `//!` comments are describing the entire
module, rather than the `use` declaration(s) that immediately follows.
This makes their intent and expected location clearer. We see some
examples where these comments were not clearly separate from `use`
declarations, which made it hard to understand what the comment is
describing.
People were tripped up by the "precludes", interpreting it that this function
must not ever be used in cryptographic contexts rather than the std lib merely
making zero promises about it being fit-for-purpose.
What remains unchanged is that if someone does try to use it *despite the warnings*
then it is on them to pin their compiler versions and verify the assembly of every
single binary build they do.
Return opaque type from PanicInfo::message()
This changes the return type of the (unstable) PanicInfo::message() method to an opaque type (that implements Display). This allows for a bit more flexibility in the future.
See https://github.com/rust-lang/rust/issues/66745
Due to refactoring the const_trait usage, the CopyMarker impl was
accidentally deleted, which had the consequence that the Copy
specialization for the small-sort was never picked.
The changes made only a limited improvement for the current small
miri coverage and in general test coverage of the sort implementations.
But they exploded test times from ~13s to ~240s, which is not deemed
worth it.
Freeze + Copy types should be allowed to choose between all three
small-sort variants. With the recent changes to small-sort selection,
a regression was added that only let such types choose between network
and fallback. It can now also choose general where appropriate.
