Move two tests from `tests/ui/std` to `library/std/tests`
Hi, there,
This pull request comes from this issue (#99417), sorry I made some mistakes creating the pull request, it's my first one.
docs: fmt::Debug*: Fix comments for finish method.
In the code sample for the `finish` method on `DebugList`, `DebugMap`, and `DebugSet`, refer to finishing the list, map, or set, rather than struct as it did.
Optimize `AtomicBool` for target that don't support byte-sized atomics
`AtomicBool` is defined to have the same layout as `bool`, which means that we guarantee that it has a size of 1 byte. However on certain architectures such as RISC-V, LLVM will emulate byte atomics using a masked CAS loop on an aligned word.
We can take advantage of the fact that `bool` only ever has a value of 0 or 1 to replace `swap` operations with `and`/`or` operations that LLVM can lower to word-sized atomic `and`/`or` operations. This takes advantage of the fact that the incoming value to a `swap` or `compare_exchange` for `AtomicBool` is often a compile-time constant.
### Example
```rust
pub fn swap_true(atomic: &AtomicBool) -> bool {
atomic.swap(true, Ordering::Relaxed)
}
```
### Old
```asm
andi a1, a0, -4
slli a0, a0, 3
li a2, 255
sllw a2, a2, a0
li a3, 1
sllw a3, a3, a0
slli a3, a3, 32
srli a3, a3, 32
.LBB1_1:
lr.w a4, (a1)
mv a5, a3
xor a5, a5, a4
and a5, a5, a2
xor a5, a5, a4
sc.w a5, a5, (a1)
bnez a5, .LBB1_1
srlw a0, a4, a0
andi a0, a0, 255
snez a0, a0
ret
```
### New
```asm
andi a1, a0, -4
slli a0, a0, 3
li a2, 1
sllw a2, a2, a0
amoor.w a1, a2, (a1)
srlw a0, a1, a0
andi a0, a0, 255
snez a0, a0
ret
```
In the code sample for the `finish` method on `DebugList`,
`DebugMap`, and `DebugSet`, refer to finishing the list, map, or
set, rather than struct as it did.
Make std tests pass on newer Android
Newer versions of Android forbid the creation of hardlinks as well as Unix domain sockets in the /data filesystem via SELinux rules, which causes several tests depending on this behavior to fail. So let's skip these tests on Android if we see an EACCES from one of these syscalls. To achieve this, introduce a macro with the horrible name of or_panic_or_skip_on_android_eacces (better suggestions welcome) which skips (returns from) the test if an EACCES return value is seen on Android.
`AtomicBool` is defined to have the same layout as `bool`, which means
that we guarantee that it has a size of 1 byte. However on certain
architectures such as RISC-V, LLVM will emulate byte atomics using a
masked CAS loop on an aligned word.
We can take advantage of the fact that `bool` only ever has a value of 0
or 1 to replace `swap` operations with `and`/`or` operations that LLVM
can lower to word-sized atomic `and`/`or` operations. This takes
advantage of the fact that the incoming value to a `swap` or
`compare_exchange` for `AtomicBool` is often a compile-time constant.
This changes the bootstrap config `target.*.profiler` from a plain bool
to also allow a string, which will be used as a path to the pre-built
profiling runtime for that target. Then `profiler_builtins/build.rs`
reads that in a `LLVM_PROFILER_RT_LIB` environment variable.
Add `x86_64-unikraft-linux-musl` target
This introduces `x86_64-unikraft-linux-musl` as the first Rust target for the [Unikraft] Unikernel Development Kit.
[Unikraft]: https://unikraft.org/
Unikraft imitates Linux and uses musl as libc.
It is extremely configurable, and does not even provide a `poll` implementation or a network stack, unless enabled by the end user who compiles the application.
Our approach for integrating the build process with `rustc` is to hide the build process as well as the actual final linking step behind a linker-shim (`kraftld`, see https://github.com/unikraft/kraftkit/issues/612).
## Tier 3 target policy
> - A tier 3 target must have a designated developer or developers (the "target
> maintainers") on record to be CCed when issues arise regarding the target.
> (The mechanism to track and CC such developers may evolve over time.)
I will be the target maintainer.
> - Targets must use naming consistent with any existing targets; for instance, a
> target for the same CPU or OS as an existing Rust target should use the same
> name for that CPU or OS. Targets should normally use the same names and
> naming conventions as used elsewhere in the broader ecosystem beyond Rust
> (such as in other toolchains), unless they have a very good reason to
> diverge. Changing the name of a target can be highly disruptive, especially
> once the target reaches a higher tier, so getting the name right is important
> even for a tier 3 target.
> - Target names should not introduce undue confusion or ambiguity unless
> absolutely necessary to maintain ecosystem compatibility. For example, if
> the name of the target makes people extremely likely to form incorrect
> beliefs about what it targets, the name should be changed or augmented to
> disambiguate it.
> - If possible, use only letters, numbers, dashes and underscores for the name.
> Periods (`.`) are known to cause issues in Cargo.
The target name `x86_64-unikraft-linux-musl` was derived from `x86_64-unknown-linux-musl`, setting Unikraft as vendor.
Unikraft exactly imitates Linux + musl.
> - Tier 3 targets may have unusual requirements to build or use, but must not
> create legal issues or impose onerous legal terms for the Rust project or for
> Rust developers or users.
> - The target must not introduce license incompatibilities.
> - Anything added to the Rust repository must be under the standard Rust
> license (`MIT OR Apache-2.0`).
> - The target must not cause the Rust tools or libraries built for any other
> host (even when supporting cross-compilation to the target) to depend
> on any new dependency less permissive than the Rust licensing policy. This
> applies whether the dependency is a Rust crate that would require adding
> new license exceptions (as specified by the `tidy` tool in the
> rust-lang/rust repository), or whether the dependency is a native library
> or binary. In other words, the introduction of the target must not cause a
> user installing or running a version of Rust or the Rust tools to be
> subject to any new license requirements.
> - Compiling, linking, and emitting functional binaries, libraries, or other
> code for the target (whether hosted on the target itself or cross-compiling
> from another target) must not depend on proprietary (non-FOSS) libraries.
> Host tools built for the target itself may depend on the ordinary runtime
> libraries supplied by the platform and commonly used by other applications
> built for the target, but those libraries must not be required for code
> generation for the target; cross-compilation to the target must not require
> such libraries at all. For instance, `rustc` built for the target may
> depend on a common proprietary C runtime library or console output library,
> but must not depend on a proprietary code generation library or code
> optimization library. Rust's license permits such combinations, but the
> Rust project has no interest in maintaining such combinations within the
> scope of Rust itself, even at tier 3.
> - "onerous" here is an intentionally subjective term. At a minimum, "onerous"
> legal/licensing terms include but are *not* limited to: non-disclosure
> requirements, non-compete requirements, contributor license agreements
> (CLAs) or equivalent, "non-commercial"/"research-only"/etc terms,
> requirements conditional on the employer or employment of any particular
> Rust developers, revocable terms, any requirements that create liability
> for the Rust project or its developers or users, or any requirements that
> adversely affect the livelihood or prospects of the Rust project or its
> developers or users.
No dependencies were added to Rust.
Requirements for linking are [Unikraft] and [KraftKit] (both BSD-3-Clause), but none of these are added to Rust.
[KraftKit]: https://github.com/unikraft/kraftkit
> - Neither this policy nor any decisions made regarding targets shall create any
> binding agreement or estoppel by any party. If any member of an approving
> Rust team serves as one of the maintainers of a target, or has any legal or
> employment requirement (explicit or implicit) that might affect their
> decisions regarding a target, they must recuse themselves from any approval
> decisions regarding the target's tier status, though they may otherwise
> participate in discussions.
> - This requirement does not prevent part or all of this policy from being
> cited in an explicit contract or work agreement (e.g. to implement or
> maintain support for a target). This requirement exists to ensure that a
> developer or team responsible for reviewing and approving a target does not
> face any legal threats or obligations that would prevent them from freely
> exercising their judgment in such approval, even if such judgment involves
> subjective matters or goes beyond the letter of these requirements.
Understood.
I am not a member of a Rust team.
> - Tier 3 targets should attempt to implement as much of the standard libraries
> as possible and appropriate (`core` for most targets, `alloc` for targets
> that can support dynamic memory allocation, `std` for targets with an
> operating system or equivalent layer of system-provided functionality), but
> may leave some code unimplemented (either unavailable or stubbed out as
> appropriate), whether because the target makes it impossible to implement or
> challenging to implement. The authors of pull requests are not obligated to
> avoid calling any portions of the standard library on the basis of a tier 3
> target not implementing those portions.
Understood.
`std` is supported.
> - The target must provide documentation for the Rust community explaining how
> to build for the target, using cross-compilation if possible. If the target
> supports running binaries, or running tests (even if they do not pass), the
> documentation must explain how to run such binaries or tests for the target,
> using emulation if possible or dedicated hardware if necessary.
Building is described in the platform support doc.
It will be updated once proper `kraftld` support has landed.
> - Tier 3 targets must not impose burden on the authors of pull requests, or
> other developers in the community, to maintain the target. In particular,
> do not post comments (automated or manual) on a PR that derail or suggest a
> block on the PR based on a tier 3 target. Do not send automated messages or
> notifications (via any medium, including via ``@`)` to a PR author or others
> involved with a PR regarding a tier 3 target, unless they have opted into
> such messages.
> - Backlinks such as those generated by the issue/PR tracker when linking to
> an issue or PR are not considered a violation of this policy, within
> reason. However, such messages (even on a separate repository) must not
> generate notifications to anyone involved with a PR who has not requested
> such notifications.
Understood.
> - Patches adding or updating tier 3 targets must not break any existing tier 2
> or tier 1 target, and must not knowingly break another tier 3 target without
> approval of either the compiler team or the maintainers of the other tier 3
> target.
> - In particular, this may come up when working on closely related targets,
> such as variations of the same architecture with different features. Avoid
> introducing unconditional uses of features that another variation of the
> target may not have; use conditional compilation or runtime detection, as
> appropriate, to let each target run code supported by that target.
I don't think this PR breaks anything.
r? compiler-team
delete [allow(unused_unsafe)] from issue #74838
While looking into issue #111288 I noticed the following `#[allow(...)]` with a `FIXME` asking for it to be removed. Deleting the `#[allow(...)]` does not seem to break anything, it seems like the lint has been updated for unsafe blocks in macros?
Add #[inline] to core debug assertion helpers
These functions are called a lot and not inlined by default in a dev compiler. Adding `#[inline]` should improve things in a dev workflow and be irrelevant in the distributed library.
The status quo is highly confusing, since the overlap is not apparent,
and specialization is not a feature of Rust. This addresses #87545;
I'm not certain if it closes it, since that issue might also be trackign
a *general* solution for hiding specializing impls automatically.
Multibyte character removal in String::pop and String::remove doctests
I think it would be useful to have the doctests for the `String::pop()` and `String::remove()` methods demonstrate that they work on multibyte UTF-8 sequences.
Fix size_hint for EncodeUtf16
More realistic upper and lower bounds, and handle the case where the iterator is located within a surrogate pair.
Resolves#113897
fix docs & example for `std::os::unix::prelude::FileExt::write_at`
Changelog:
* used `File::create` instead of `File::read` to get a writeable file
* explicity mentioned the bug with `pwrite64` in docs
Unfortunately, I don't think that there is really much we can do about this since the feature has already been stabilised.
We could potentially add a clippy lint warning people on Linux that using `write_at` with the `O_APPEND` flag does not exhibit the behaviour that they would have assumed.
fixes#113627
Allow limited access to `OsString` bytes
This extends #109698 to allow no-cost conversion between `Vec<u8>` and `OsString` as suggested in feedback from `os_str_bytes` crate in #111544.
Update the tracking issue for `const_cstr_from_ptr`
Tracking issue #101719 was for `const_cstr_methods`, #113219 is a new issue specific for `const_cstr_from_ptr`.
(I believe #101719 could also be closed)
```@rustbot``` label +T-libs-api +A-docs
Minor improvements to Windows TLS dtors
This does a few things:
* Moves keyless dtors into the same module as the `on_tls_callback` function because of dylib mess. We keep the `inline(never)` hints as a precaution (see also the issue they link to).
* Introduces the `HAS_DTORS` atomic as an optimization hint. This allows removing (most) of the TLS dtor code if no dtors are ever run. Otherwise it's always included because of a `#[used]`.
* Only run either keyed dtors or keyless dtors but not both. They should be mutually exclusive as keyed dtors are a fallback. I've also added an `assert` to make sure this is true.
std: remove an allocation in `Path::with_extension`
`Path::with_extension` used to reallocate (and copy) paths twice per call, now it does it once, by checking the size of the previous and new extensions it's possible to call `PathBuf::with_capacity` and pass the exact capacity required.
This also reduces the memory consumption of the path returned from `Path::with_extension` by using exact capacity instead of using amortized exponential growth.
remove the unstable `core::sync::atomic::ATOMIC_*_INIT` constants
Tracking issue: #99069
It would be weird to ever stabilise these as they are already deprecated.
Update documentation for std::process::Command's new method
In the current documentation, it's not specified that when creating a Command, the .exe extension can be omitted for Windows executables. However, for other types of executable files like .bat or .cmd, the complete filename including the extension must be provided.
I encountered it by noticing that `Command::new("wt").spawn().unwrap()` succeeds on my machine while `Command::new("code").spawn().unwrap()` panics. Turns out VS Code's entrypoint is .cmd file.
`resolve_exe` method mentions this behaviour in [a comment](e7fda447e7/library/std/src/sys/windows/process.rs (L425)), but it makes sense to mention it at a more visible place.
I've added this clarification to the documentation, which should make it more accurate and helpful for Rust developers working on the Windows platform.
Implement rust-lang/compiler-team#578.
When an ICE is encountered on nightly releases, the new rustc panic
handler will also write the contents of the backtrace to disk. If any
`delay_span_bug`s are encountered, their backtrace is also added to the
file. The platform and rustc version will also be collected.
In the current documentation, it's not specified that when creating
a Command, the .exe extension can be omitted for Windows executables.
However, for other types of executable files like .bat or .cmd,
the complete filename including the extension must be provided.
I encountered it by noticing that `Command::new("wt").spawn().unwrap()`
succeeds on my machine while `Command::new("code").spawn().unwrap()`
panics. Turns out VS Code's entrypoint is .cmd file.
`resolve_exe` method mentions this behaviour in a comment[1], but it
makes sense to mention it at more visible place.
I've added this clarification to the documentation, which should
make it more accurate and helpful for Rust developers
working on the Windows platform.
[1] e7fda447e7/library/std/src/sys/windows/process.rs (L425)
Add support for allocators in `Rc` & `Arc`
Adds the ability for `std::rc:Rc`, `std::rc::Weak`, `std::sync::Arc`, and `std::sync::Weak` to live in custom allocators
Rename VecDeque's `rotate_left` and `rotate_right` parameters
This pull request introduces a modification to the `VecDeque` collection, specifically the `rotate_left` and `rotate_right` functions, by renaming the parameter associated with these functions.
The rationale behind this change is to provide clearer and more consistent naming for the parameter that specifies the number of places to rotate the double-ended queue. By using `n` as the parameter name in both functions, it becomes easier to understand and remember the purpose of the parameter.
Like the other CStr and CString error types, make a re-export for
std::ffi::FromBytesUntilNulError.
This seems to have slipped through the cracks in the
cstr_from_bytes_until_nul implementation and core_c_str migration.
Tracking Issue: #95027
Eliminate ZST allocations in `Box` and `Vec`
This PR fixes 2 issues with `Box` and `RawVec` related to ZST allocations. Specifically, the `Allocator` trait requires that:
- If you allocate a zero-sized layout then you must later deallocate it, otherwise the allocator may leak memory.
- You cannot pass a ZST pointer to the allocator that you haven't previously allocated.
These restrictions exist because an allocator implementation is allowed to allocate non-zero amounts of memory for a zero-sized allocation. For example, `malloc` in libc does this.
Currently, ZSTs are handled differently in `Box` and `Vec`:
- `Vec` never allocates when `T` is a ZST or if the vector capacity is 0.
- `Box` just blindly passes everything on to the allocator, including ZSTs.
This causes problems due to the free conversions between `Box<[T]>` and `Vec<T>`, specifically that ZST allocations could get leaked or a dangling pointer could be passed to `deallocate`.
This PR fixes this by changing `Box` to not allocate for zero-sized values and slices. It also fixes a bug in `RawVec::shrink` where shrinking to a size of zero did not actually free the backing memory.
Adjustments for RustyHermit
The interface between `libstd` and the OS changed and some changes are not correctly merged for RustHermit. For instance, the crate `hermit_abi` isn't defined as public, although it provided the socket interface for the application.
In addition, the support of thread::available_parallelism is realized. It returns the number of available processors.
Enable coinduction support for Safe Transmute
This patch adds the `#[rustc_coinductive]` annotation to `BikeshedIntrinsicFrom`, so that it's possible to compute transmutability for recursive types.
## Motivation
Safe Transmute currently already supports references (#110662). However, if a type is implemented recursively, it leads to an infinite loop when we try to check if transmutation is safe.
A couple simple examples that one might want to write, that are currently not possible to check transmutability for:
```rs
#[repr(C)] struct A(&'static B);
#[repr(C)] struct B(&'static A);
```
```rs
#[repr(C)]
enum IList<'a> { Nil, Cons(isize, &'a IList<'a>) }
#[repr(C)]
enum UList<'a> { Nil, Cons(usize, &'a UList<'a>) }
```
Previously, `@jswrenn` was considering writing a co-inductive solver from scratch, just for the `rustc_tranmsute` crate. Later on as I started working on Safe Transmute myself, I came across the `#[rustc_coinductive]` annotation, which is currently only being used for the `Sized` trait. Leveraging this trait actually solved the problem entirely, and it saves a lot of duplicate work that would have had to happen in `rustc_transmute`.
Uplift `clippy::fn_null_check` lint
This PR aims at uplifting the `clippy::fn_null_check` lint into rustc.
## `incorrect_fn_null_checks`
(warn-by-default)
The `incorrect_fn_null_checks` lint checks for expression that checks if a function pointer is null.
### Example
```rust
let fn_ptr: fn() = /* somehow obtained nullable function pointer */
if (fn_ptr as *const ()).is_null() { /* ... */ }
```
### Explanation
Function pointers are assumed to be non-null, checking for their nullity is incorrect.
-----
Mostly followed the instructions for uplifting a clippy lint described here: https://github.com/rust-lang/rust/pull/99696#pullrequestreview-1134072751
`@rustbot` label: +I-lang-nominated
r? compiler
Add `Read`, `Write` and `Seek` impls for `Arc<File>` where appropriate
If `&T` implements these traits, `Arc<T>` has no reason not to do so
either. This is useful for operating system handles like `File` or
`TcpStream` which don't need a mutable reference to implement these
traits.
CC #53835.
CC #94744.
move pal cfgs in f32 and f64 to sys
I'd like to push forward on `sys` being a separate crate. To start with, most of these PAL exception cases are very simple little bits of code like this, so I thought I would try tidying them up.
Revert "alloc: Allow comparing Boxs over different allocators", add regression test
Temporary fix for #113283
Adds a test to fix the regression introduced in 001b081cc1 and revert that commit. The test fails without the revert.
Revert the lexing of `c"…"` string literals
Fixes \[after beta-backport\] #113235.
Further progress is tracked in #113333.
This PR *manually* reverts parts of #108801 (since a git-revert would've been too coarse-grained & messy)
and git-reverts #111647.
CC `@fee1-dead` (#108801) `@klensy` (#111647)
r? `@compiler-errors`
`@rustbot` label F-c_str_literals beta-nominated
enable test_join test in Miri
Miri for quite a while now has a hack to support self-referential generators: non-`Unique` mutable references are exempt from aliasing conditions. So we can run this test now. (It passes.)
Also extend a comment in a Vec test, while I am at it.
This reverts commit 001b081cc1.
This change was done as the above commit introduces a regression in type
inference. Regression test located at
`tests/ui/type-inference/issue-113283-alllocator-trait-eq.rs`
Rollup of 3 pull requests
Successful merges:
- #113253 (Fixed documentation of from<CString> for Rc<CStr>: Arc -> Rc)
- #113258 (Migrate GUI colors test to original CSS color format)
- #113259 (Suggest `x build library` for a custom toolchain that fails to load `core`)
r? `@ghost`
`@rustbot` modify labels: rollup
Test benchmarks with `-Z panic-abort-tests`
During test execution, when a `#[bench]` benchmark is encountered it's executed once to check whether it works. Unfortunately that was not compatible with `-Z panic-abort-tests`: the feature works by spawning a subprocess for each test, which prevents the use of dynamic tests as we cannot pass closures to child processes, and before this PR the conversion from benchmark to test was done by turning benchmarks into dynamic tests whose closures execute the benchmark once.
The approach this PR took was to add two new kinds of `TestFn`s: `StaticBenchAsTestFn` and `DynBenchAsTestFn` (⚠️ **this is a breaking change** ⚠️). With that change, a `StaticBenchFn` can be converted into a `StaticBenchAsTestFn` without creating dynamic tests, and making it possible to test `#[bench]` functions with `-Z panic-abort-tests`. The subprocess test runner also had to be updated to perform the conversion from benchmark to test when appropriate.
Along with the bug fix, in the first commit I refactored how tests are executed: rather than executing the test function in multiple places across `libtest`, there is now a private `TestFn::into_runnable()` method, which returns either a `RunnableTest` or `RunnableBench`, on which you can call the `run()` method. This simplified the rest of the changes in the PR.
This PR is best reviewed commit-by-commit.
Fixes https://github.com/rust-lang/rust/issues/73509
Mark wrapped intrinsics as inline(always)
This should mitigate having the inliner decide not to inline when the architecture is lacking an implementation of
TargetTransformInfo::areInlineCompatible aware of the target features (e.g. PowerPC as today).
See https://github.com/rust-lang/stdarch/pull/1443#issuecomment-1613788080
This should mitigate having the inliner decide not to inline when
the architecture is lacking an implementation of
TargetTransformInfo::areInlineCompatible aware of the target
features (e.g. PowerPC as today).
Stabilize `const_cstr_methods`
This PR seeks to stabilize `const_cstr_methods`. Fixes most of #101719
## New const stable API
```rust
impl CStr {
// depends: memchr
pub const fn from_bytes_with_nul(bytes: &[u8]) -> Result<&Self, FromBytesWithNulError> {...}
// depends: const_slice_index
pub const fn to_bytes(&self) -> &[u8] {}
// depends: pointer casts
pub const fn to_bytes_with_nul(&self) -> &[u8] {}
// depends: str::from_utf8
pub const fn to_str(&self) -> Result<&str, str::Utf8Error> {}
}
```
I don't think any of these methods will have any issue when `CStr` becomes a thin pointer as long as `memchr` is const (which also allows for const `strlen`) .
## Notes
- `from_bytes_until_nul` relies on `const_slice_index`, which relies on `const_trait_impls`, and generally this should be avoided. After talking with Oli, it should be OK in this case because we could replace the ranges with pointer tricks if needed (worst case being those feature gates disappear). https://github.com/rust-lang/rust/pull/107624#discussion_r1101468480
- Making `from_ptr` const is deferred because it depends on `const_eval_select`. I have moved this under the new flag `const_cstr_from_ptr` https://github.com/rust-lang/rust/pull/107624#discussion_r1101555239
cc ``@oli-obk`` I think you're the const expert
``@rustbot`` modify labels: +T-libs-api +needs-fcp
This patch adds the `#[rustc_coinductive]` annotation to
`BikeshedIntrinsicFrom`, so that it's possible to compute transmutability for
recursive types.
`Path::with_extension` used to reallocate (and copy) paths twice per
call, now it does it once, by checking the size of the previous and new
extensions it's possible to call `PathBuf::with_capacity` and pass the
exact capacity it takes.
Also reduce the memory consumption of the path returned from
`Path::with_extension` by using exact capacity instead of using
amortized exponential growth.
Allow comparing `Box`es with different allocators
Currently, comparing `Box`es over different allocators is not allowed:
```Rust
error[E0308]: mismatched types
--> library/alloc/tests/boxed.rs:22:20
|
22 | assert_eq!(b1, b2);
| ^^ expected `Box<{integer}, ConstAllocator>`, found `Box<{integer}, AnotherAllocator>`
|
= note: expected struct `Box<{integer}, ConstAllocator>`
found struct `Box<{integer}, AnotherAllocator>`
For more information about this error, try `rustc --explain E0308`.
error: could not compile `alloc` (test "collectionstests") due to previous error
```
This PR lifts this limitation
remove unused field
Followup to #104455. The field is no longer needed since ExtractIf (previously DrainFilter) doesn't keep draining in its drop impl.
Specialize `StepBy<Range<{integer}>>`
OLD
iter::bench_range_step_by_fold_u16 700.00ns/iter +/- 10.00ns
iter::bench_range_step_by_fold_usize 519.00ns/iter +/- 6.00ns
iter::bench_range_step_by_loop_u32 555.00ns/iter +/- 7.00ns
iter::bench_range_step_by_sum_reducible 37.00ns/iter +/- 0.00ns
NEW
iter::bench_range_step_by_fold_u16 49.00ns/iter +/- 0.00ns
iter::bench_range_step_by_fold_usize 194.00ns/iter +/- 1.00ns
iter::bench_range_step_by_loop_u32 98.00ns/iter +/- 0.00ns
iter::bench_range_step_by_sum_reducible 1.00ns/iter +/- 0.00ns
NEW + `-Ctarget-cpu=x86-64-v3`
iter::bench_range_step_by_fold_u16 22.00ns/iter +/- 0.00ns
iter::bench_range_step_by_fold_usize 80.00ns/iter +/- 1.00ns
iter::bench_range_step_by_loop_u32 41.00ns/iter +/- 0.00ns
iter::bench_range_step_by_sum_reducible 1.00ns/iter +/- 0.00ns
I have only optimized for walltime of those methods, I haven't tested whether it eliminates bounds checks when indexing into slices via things like `(0..slice.len()).step_by(16)`.
Move windows-sys arm32 shim to c.rs
This moves the arm32 shim in to c.rs instead of appending to the generated file itself.
This makes it simpler to change these workarounds if/when needed. The downside is we need to exclude a couple of functions from being generated (see the comment). A metadata solution could help here but they'll be easy enough to add back if that happens.
Remove unnecessary `path` attribute
Follow up to #111401. I missed this at the time but it should now be totally unnecessary since the other include was removed.
r? `@workingjubilee`
Expose `compiler-builtins-weak-intrinsics` feature for `-Zbuild-std`
This was added in rust-lang/compiler-builtins#526 to force all compiler-builtins intrinsics to use weak linkage.
Implement `Sync` for `mpsc::Sender`
`mpsc::Sender` is currently `!Sync` because the previous implementation contained an optimization where the channel started out as single-producer and was dynamically upgraded on the first clone, which relied on a unique reference to the sender. This optimization is one of the main reasons the old implementation was so complex and was removed in #93563. `mpsc::Sender` can now soundly implement `Sync`.
Note for any potential confusion, this chance does *not* add MPMC behavior. This only affects the already `Send + Clone` *sender*, not *receiver*.
It's technically possible to rely on the `!Sync` behavior in the same way as a `PhantomData<*mut T>`, but that seems very unlikely in practice. Either way, this change is insta-stable and needs an FCP.
`@rustbot` label +T-libs-api -T-libs
If `&T` implements these traits, `Arc<T>` has no reason not to do so
either. This is useful for operating system handles like `File` or
`TcpStream` which don't need a mutable reference to implement these
traits.
CC #53835.
CC #94744.
slice::from_raw_parts: mention no-wrap-around condition
Cc https://github.com/rust-lang/rust/issues/83996. This probably needs to be mentioned in more places, so I am not closing that issue, but this here should help at least.
For ranges < usize we determine the number of items
StepBy would yield and then store that in the range.end
instead of the actual end. This significantly
simplifies calculation of the loop induction variable
especially in cases where StepBy::step (an usize)
could overflow the Range's item type
Warn on unused `offset_of!()` result
The usage of `core::hint::must_use()` means that we don't get a specialized message. I figured out that since there are plenty of other methods that just have `#[must_use]` with no message it'll be fine, but it is a bit unfortunate that the error mentions `must_use` and not `offset_of!`.
Fixes#111669.
Document memory orderings of `thread::{park, unpark}`
Document `thread::park/unpark` as having acquire/release synchronization. Without that guarantee, even the example in the documentation can deadlock:
```rust
let flag = Arc::new(AtomicBool::new(false));
let t2 = thread::spawn(move || {
while !flag.load(Ordering::Acquire) {
thread::park();
}
});
flag.store(true, Ordering::Release);
t2.thread().unpark();
// t1: flag.store(true)
// t1: thread.unpark()
// t2: flag.load() == false
// t2 now parks, is immediately unblocked but never
// acquires the flag, and thus spins forever
```
Multiple calls to `unpark` should also maintain a release sequence to make sure operations released by previous `unpark`s are not lost:
```rust
let a = Arc::new(AtomicBool::new(false));
let b = Arc::new(AtomicBool::new(false));
let t2 = thread::spawn(move || {
while !a.load(Ordering::Acquire) || !b.load(Ordering::Acquire) {
thread::park();
}
});
thread::spawn(move || {
a.store(true, Ordering::Release);
t2.thread().unpark();
});
b.store(true, Ordering::Release);
t2.thread().unpark();
// t1: a.store(true)
// t1: t2.unpark()
// t3: b.store(true)
// t3: t2.unpark()
// t2 now parks, is immediately unblocked but never
// acquires the store of `a`, only the store of `b` which
// was released by the most recent unpark, and thus spins forever
```
This is of course a contrived example, but is reasonable to rely upon in real code.
Note that all implementations of park/unpark already comply with the rules, it's just undocumented.
Implement PartialOrd for `Vec`s over different allocators
It is already possible to `PartialEq` `Vec`s with different allocators, but that is not the case with `PartialOrd`.
