Remove len argument from RawVec::reserve_for_push
Removes `RawVec::reserve_for_push`'s `len` argument since it's always the same as capacity.
Also makes `Vec::insert` use `RawVec::reserve_for_push`.
Stabilize `unchecked_{add,sub,mul}`
Tracking issue: #85122
I think we might as well just stabilize these basic three. They're the ones that have `nuw`/`nsw` flags in LLVM.
Notably, this doesn't include the potentially-more-complex or -more-situational things like `unchecked_neg` or `unchecked_shr` that are under different feature flags.
To quote Ralf https://github.com/rust-lang/rust/issues/85122#issuecomment-1681669646,
> Are there any objections to stabilizing at least `unchecked_{add,sub,mul}`? For those there shouldn't be any surprises about what their safety requirements are.
*Semantially* these are [already available on stable, even in `const`, via](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=bdb1ff889b61950897f1e9f56d0c9a36) `checked_*`+`unreachable_unchecked`. So IMHO we might as well just let people write them directly, rather than try to go through a `let Some(x) = x.checked_add(y) else { unsafe { hint::unreachable_unchecked() }};` dance.
I added additional text to each method to attempt to better describe the behaviour and encourage `wrapping_*` instead.
r? rust-lang/libs-api
Add detection of [Partial]Ord methods in the `ambiguous_wide_pointer_comparisons` lint
Partially addresses https://github.com/rust-lang/rust/issues/121264 by adding diagnostics items for PartialOrd and Ord methods, detecting such diagnostics items as "binary operation" and suggesting the correct replacement.
I also took the opportunity to change the suggestion to use new methods `.cast()` on `*mut T` an d `*const T`.
Because `HashMap::with_hasher` constness is being stabilized this will
in turn allow creating empty HashMap<K,V,BuildHasherDefault<H>> in const
context for any H: Default + Hasher.
Eliminate `UbChecks` for non-standard libraries
The purpose of this PR is to allow other passes to treat `UbChecks` as constants in MIR for optimization after #122629.
r? RalfJung
Codegen const panic messages as function calls
This skips emitting extra arguments at every callsite (of which there
can be many). For a librustc_driver build with overflow checks enabled,
this cuts 0.7MB from the resulting shared library (see [perf]).
A sample improvement from nightly:
```
leaq str.0(%rip), %rdi
leaq .Lalloc_d6aeb8e2aa19de39a7f0e861c998af13(%rip), %rdx
movl $25, %esi
callq *_ZN4core9panicking5panic17h17cabb89c5bcc999E@GOTPCREL(%rip)
```
to this PR:
```
leaq .Lalloc_d6aeb8e2aa19de39a7f0e861c998af13(%rip), %rdi
callq *_RNvNtNtCsduqIKoij8JB_4core9panicking11panic_const23panic_const_div_by_zero@GOTPCREL(%rip)
```
[perf]: https://perf.rust-lang.org/compare.html?start=a7e4de13c1785819f4d61da41f6704ed69d5f203&end=64fbb4f0b2d621ff46d559d1e9f5ad89a8d7789b&stat=instructions:u
`num::NonZero::get` can be 1 transmute instead of 2
Just something I noticed in passing. No need for a `match` in here to call `unreachable_unchecked`, as `transmute_unchecked` will add the appropriate `llvm.assume` <https://rust.godbolt.org/z/W5hjeETnc>.
Clarify atomic bit validity
The previous definition used the phrase "representation", which is ambiguous given the current state of memory model nomenclature in Rust. For integer types and for `AtomicPtr<T>`, the new wording clarifies that size and bit validity are guaranteed to match the corresponding native integer type/`*mut T`. For `AtomicBool`, the new wording clarifies that size, alignment, and bit validity are guaranteed to match `bool`.
Note that we use the phrase "size and alignment" rather than "layout" since the latter term also implies that the field types are the same. This isn't true - `AtomicXxx` doesn't store an `xxx`, but rather an `UnsafeCell<xxx>`. This distinction is important for some `unsafe` code, which needs to reason about the presence or absence of interior mutability in order to ensure that their code is sound (see e.g. https://github.com/google/zerocopy/issues/251).
Soft-destabilize `RustcEncodable` & `RustcDecodable`, remove from prelude in next edition
cc rust-lang/libs-team#272
Any use of `RustcEncodable` and `RustcDecodable` now triggers a deny-by-default lint. The derives have been removed from the 2024 prelude. I specifically chose **not** to document this in the module-level documentation, as the presence in existing preludes is not documented (which I presume is intentional).
This does not implement the proposed change for `rustfix`, which I will be looking into shortly.
With regard to the items in the preludes being stable, this should not be an issue because #15702 has been resolved.
r? libs-api
Update `RwLock` deadlock example to not use shadowing
Tweak variable names in the deadlock example to remove any potential confusion that the behavior is somehow shadowing-related.
Implement `Vec::pop_if`
This PR adds `Vec::pop_if` to the public API, behind the `vec_pop_if` feature.
```rust
impl<T> Vec<T> {
pub fn pop_if<F>(&mut self, f: F) -> Option<T>
where F: FnOnce(&mut T) -> bool;
}
```
Tracking issue: #122741
## Open questions
- [ ] Should the first unit test be split up?
- [ ] I don't see any guidance on ordering of methods in impl blocks, should I move the method elsewhere?
unix fs: Make hurd using explicit new rather than From
408c0ea216 ("unix time module now return result") dropped the From impl for SystemTime, breaking the hurd build (and probably the horizon build)
Fixes#123032
Fix doc link to BufWriter in std::fs::File documentation
It seems that doc link to `BufWriter` in `std::fs::File` doc leads to `BufReader`, not `BufWriter`.
See https://doc.rust-lang.org/std/fs/struct.File.html
Simplify proc macro bridge state
Currently, `proc_macro` uses a `ScopedCell` to store the client-side proc-macro bridge. Unfortunately, this requires the `Bridge`, which has non-negligible size, to be copied out and back again on every access. In some cases, the optimizer might be able to elide these copies, but in general, this is suboptimal.
This PR removes `ScopedCell` and employs a similar trick as in [`scoped_tls`](https://crates.io/crates/scoped-tls), meaning that the only thing stored in TLS is a pointer to the state, which now is a `RefCell`. Access to the pointer is then scoped so that it is always within the lifetime of the reference to the state. Unfortunately, `scoped_tls` requires the referenced type to be `'static`, which `Bridge` is not, therefore we cannot simply copy that macro but have to reimplement its TLS trick.
This removes the `#[forbid(unsafe_code)]` on the `client` module so that we do not have to export `Bridge`, which currently is private, to the whole crate. I can change that, if necessary.
Import the 2021 prelude in the core crate
The `core` crate currently imports the v1 prelude
b3df0d7e5e/library/core/src/lib.rs (L285-L287)
This recently caused an issue when updating the `portable-simd` subtree since it was using a trait that was added to the 2021 prelude: https://github.com/rust-lang/rust/pull/122905#discussion_r1536228822
To make it easier to have a consistent build environment for subtrees and submodules that get included in `core`, we will now import the 2021 prelude into `core`.
Fixes#122912
r? `@Nilstrieb`
warning: casting raw pointers to the same type and constness is unnecessary (`*mut V` -> `*mut V`)
--> library\alloc\src\collections\btree\map\entry.rs:357:31
|
357 | let val_ptr = root.borrow_mut().push(self.key, value) as *mut V;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `root.borrow_mut().push
(self.key, value)`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_cast
warning: casting to the same type is unnecessary (`usize` -> `usize`)
--> library\alloc\src\ffi\c_str.rs:411:56
|
411 | let slice = slice::from_raw_parts_mut(ptr, len as usize);
| ^^^^^^^^^^^^ help: try: `len`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_cast
warning: casting raw pointers to the same type and constness is unnecessary (`*mut T` -> `*mut T`)
--> library\alloc\src\slice.rs:516:25
|
516 | (buf.as_mut_ptr() as *mut T).add(buf.len()),
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `buf.as_mut_ptr()`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_cast
warning: casting raw pointers to the same type and constness is unnecessary (`*mut T` -> `*mut T`)
--> library\alloc\src\slice.rs:537:21
|
537 | (buf.as_mut_ptr() as *mut T).add(buf.len()),
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `buf.as_mut_ptr()`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_cast
warning: casting raw pointers to the same type and constness is unnecessary (`*const ()` -> `*const ()`)
--> library\alloc\src\task.rs:151:13
|
151 | waker as *const (),
| ^^^^^^^^^^^^^^^^^^ help: try: `waker`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_cast
warning: casting raw pointers to the same type and constness is unnecessary (`*const ()` -> `*const ()`)
--> library\alloc\src\task.rs:323:13
|
323 | waker as *const (),
| ^^^^^^^^^^^^^^^^^^ help: try: `waker`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_cast
warning: casting to the same type is unnecessary (`usize` -> `usize`)
--> library\std\src\sys_common\net.rs:110:21
|
110 | assert!(len as usize >= mem::size_of::<c::sockaddr_in>());
| ^^^^^^^^^^^^ help: try: `len`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_cast
warning: casting to the same type is unnecessary (`usize` -> `usize`)
--> library\std\src\sys_common\net.rs:116:21
|
116 | assert!(len as usize >= mem::size_of::<c::sockaddr_in6>());
| ^^^^^^^^^^^^ help: try: `len`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_cast
Clarify transmute example
The example claims using an iterator will copy the entire vector, but this is not true in practice thanks to internal specializations in the stdlib (see https://godbolt.org/z/cnxo3MYs5 for confirmation that this doesn't reallocate nor iterate over the vec's elements). Since neither the copy nor the optimization is guaranteed I opted for saying that they _may_ happen.
This saves some debug and scope metadata in every single function that calls it.
Normally wouldn't be worth it, but with the derives there's *so* many of these.
std:🧵 refine available_parallelism for solaris/illumos.
Rather than the system-wide available cpus fallback solution, we fetch the cpus bound to the current process.
panic-in-panic-hook: formatting a message that's just a string is risk-free
This slightly improves the output in the 'panic while processing panic' case if the panic message does not involve any formatting. Follow-up to https://github.com/rust-lang/rust/pull/122930.
r? ``@Amanieu``
Rename `Arguments::as_const_str` to `as_statically_known_str`
While `const` has a particular meaning about language guarantees, here
we need a fuzzier notion like whether constant propagation was
effective, and `statically_known` is the best term we have for now.
r? ``@RalfJung``
Fix compile of wasm64-unknown-unknown target
This target is a Tier 3 target so it's not tested on CI, and it's broken since last used so this commit fixes a small unwind-related issue that cropped up in the meantime.
While `const` has a particular meaning about language guarantees, here
we need a fuzzier notion like whether constant propagation was
effective, and `statically_known` is the best term we have for now.
Rollup of 9 pull requests
Successful merges:
- #121281 (regression test for #103626)
- #122168 (Fix validation on substituted callee bodies in MIR inliner)
- #122217 (Handle str literals written with `'` lexed as lifetime)
- #122379 (transmute: caution against int2ptr transmutation)
- #122840 (`rustdoc --test`: Prevent reaching the maximum size of command-line by using files for arguments if there are too many)
- #122907 (Uniquify `ReError` on input mode in canonicalizer)
- #122942 (Add test in higher ranked subtype)
- #122943 (add a couple more ice tests)
- #122963 (core/panicking: fix outdated comment)
r? `@ghost`
`@rustbot` modify labels: rollup
transmute: caution against int2ptr transmutation
This came up in https://github.com/rust-lang/rust/pull/121282.
Cc ```@saethlin``` ```@scottmcm```
Eventually we'll add a proper description of provenance that we can reference, but that's a bunch of work and it's unclear who will have the time to do that when. Meanwhile, let's at least do what we can without mentioning provenance explicitly.
refactor check_{lang,library}_ub: use a single intrinsic
This enacts the plan I laid out [here](https://github.com/rust-lang/rust/pull/122282#issuecomment-1996917998): use a single intrinsic, called `ub_checks` (in aniticpation of https://github.com/rust-lang/compiler-team/issues/725), that just exposes the value of `debug_assertions` (consistently implemented in both codegen and the interpreter). Put the language vs library UB logic into the library.
This makes it easier to do something like https://github.com/rust-lang/rust/pull/122282 in the future: that just slightly alters the semantics of `ub_checks` (making it more approximating when crates built with different flags are mixed), but it no longer affects whether these checks can happen in Miri or compile-time.
The first commit just moves things around; I don't think these macros and functions belong into `intrinsics.rs` as they are not intrinsics.
r? `@saethlin`
Rollup of 11 pull requests
Successful merges:
- #120577 (Stabilize slice_split_at_unchecked)
- #122698 (Cancel `cargo update` job if there's no updates)
- #122780 (Rename `hir::Local` into `hir::LetStmt`)
- #122915 (Delay a bug if no RPITITs were found)
- #122916 (docs(sync): normalize dot in fn summaries)
- #122921 (Enable more mir-opt tests in debug builds)
- #122922 (-Zprint-type-sizes: print the types of awaitees and unnamed coroutine locals.)
- #122927 (Change an ICE regression test to use the original reproducer)
- #122930 (add panic location to 'panicked while processing panic')
- #122931 (Fix some typos in the pin.rs)
- #122933 (tag_for_variant follow-ups)
r? `@ghost`
`@rustbot` modify labels: rollup
Stabilize slice_split_at_unchecked
Greetings!
I took the opportunity, and I tried to stabilize the `slice_split_at_unchecked` feature. I followed the guidelines, and I hope everything was done correctly 🤞 .
Closes#76014
Let codegen decide when to `mem::swap` with immediates
Making `libcore` decide this is silly; the backend has so much better information about when it's a good idea.
Thus this PR introduces a new `typed_swap` intrinsic with a fallback body, and replaces that fallback implementation when swapping immediates or scalar pairs.
r? oli-obk
Replaces #111744, and means we'll never need more libs PRs like #111803 or #107140
This skips emitting extra arguments at every callsite (of which there
can be many). For a librustc_driver build with overflow checks enabled,
this cuts 0.7MB from the resulting binary.
Remove SpecOptionPartialEq
With the recent LLVM bump, the specialization for Option::partial_eq on types with niches is no longer necessary. I kept the manual implementation as it still gives us better codegen than the derive (will look at this seperately).
Also implemented PartialOrd/Ord by hand as it _somewhat_ improves codegen for #49892: https://godbolt.org/z/vx5Y6oW4Y
Doc Guarantee: BTree(Set|Map): `IntoIter` Iterate in Sorted by key Order
This Doc-only PR adds text to the IntoIterator implementation and IntoIter type for both BTreeMap and BTreeSet that states that the returned items will be in sorted-by-key order, this is a guarantee that is made by the iter() and iter_mut() methods of BTreeMap/Set and BTreeMap respectively, but not on into_iter methods or types.
I don't know how the IntoIter iteration would not be sorted by key, and I would like to rely on that behavior for my prefix_array crate.
The text appended to IntoIter documentation is based on each types respective iter() method documentation, as is the text used in the IntoIterator documentation; they are slightly inconsistent between Set/Map, but they are consistent within their own types documentation.
select Vec::from_iter impls in a const block to optimize compile times
Ignoring whitespace diffs should make this easier to review.
This relies on the trick from #122301
Split out from #120682
Make `type_ascribe!` not a built-in
The only weird thing is the macro expansion note. I wonder if we should suppress these 🤔
r? ````@fmease```` since you told me about builtin# lol
Add `usize::MAX` arg tests for Vec
Tests to prevent recurrence of the UB from the rust-lang/rust#122760 issue.
I skipped the `with_capacity`, `drain`, `reserve`, etc. APIs because they actually had a good assortment of tests earlier in the same file.
r? Nilstrieb
Relax SeqCst ordering in standard library.
Every single SeqCst in the standard library is unnecessary. In all cases, Relaxed or Release+Acquire was sufficient.
As I [wrote](https://marabos.nl/atomics/memory-ordering.html#common-misconceptions) in my book on atomics:
> [..] when reading code, SeqCst basically tells the reader: "this operation depends on the total order of every single SeqCst operation in the program," which is an incredibly far-reaching claim. The same code would likely be easier to review and verify if it used weaker memory ordering instead, if possible. For example, Release effectively tells the reader: "this relates to an acquire operation on the same variable," which involves far fewer considerations when forming an understanding of the code.
>
> It is advisable to see SeqCst as a warning sign. Seeing it in the wild often means that either something complicated is going on, or simply that the author did not take the time to analyze their memory ordering related assumptions, both of which are reasons for extra scrutiny.
r? ````@Amanieu```` ````@joboet````
This target is a Tier 3 target so it's not tested on CI, and it's broken
since last used so this commit fixes a small unwind-related issue that
cropped up in the meantime.
fix OOB pointer formed in Vec::index
Move the length check to before using `index` with `ptr::add` to prevent an out of bounds pointer from being formed.
Fixes#122760
For async closures, cap closure kind, get rid of `by_mut_body`
Right now we have three `AsyncFn*` traits, and three corresponding futures that are returned by the `call_*` functions for them. This is fine, but it is a bit excessive, since the future returned by `AsyncFn` and `AsyncFnMut` are identical. Really, the only distinction we need to make with these bodies is "by ref" and "by move".
This PR removes `AsyncFn::CallFuture` and renames `AsyncFnMut::CallMutFuture` to `AsyncFnMut::CallRefFuture`. This simplifies MIR building for async closures, since we don't need to build an extra "by mut" body, but just a "by move" body which is materially different.
We need to do a bit of delicate handling of the ClosureKind for async closures, since we need to "cap" it to `AsyncFnMut` in some cases when we only care about what body we're looking for.
This also fixes a bug where `<{async closure} as Fn>::call` was returning a body that takes the async-closure receiver *by move*.
This also helps align the `AsyncFn` traits to the `LendingFn` traits' eventual designs.
Expose `ucred::peer_cred` on QNX targets to enable dist builds
After following https://doc.rust-lang.org/rustc/platform-support/nto-qnx.html I attempted to run the following `x.py` command:
```bash
export build_env='
CC_aarch64-unknown-nto-qnx710=qcc
CFLAGS_aarch64-unknown-nto-qnx710=-Vgcc_ntoaarch64le_cxx
CXX_aarch64-unknown-nto-qnx710=qcc
AR_aarch64_unknown_nto_qnx710=ntoaarch64-ar
CC_x86_64-pc-nto-qnx710=qcc
CFLAGS_x86_64-pc-nto-qnx710=-Vgcc_ntox86_64_cxx
CXX_x86_64-pc-nto-qnx710=qcc
AR_x86_64_pc_nto_qnx710=ntox86_64-ar'
env $build_env ./x.py --stage 2 dist rust-std --target aarch64-unknown-nto-qnx710,x86_64-pc-nto-qnx710,x86_64-unknown-linux-gnu
```
The result was the following error:
```
Compiling object v0.32.2
Compiling std_detect v0.1.5 (/home/ana/git/rust-lang/rust/library/stdarch/crates/std_detect)
Compiling addr2line v0.21.0
error: function `peer_cred` is never used
--> library/std/src/os/unix/net/ucred.rs:89:12
|
89 | pub fn peer_cred(socket: &UnixStream) -> io::Result<UCred> {
| ^^^^^^^^^
|
= note: `-D dead-code` implied by `-D warnings`
= help: to override `-D warnings` add `#[allow(dead_code)]`
error: could not compile `std` (lib) due to 1 previous error
Build completed unsuccessfully in 0:06:25
```
I contacted `@flba-eb` and `@gh-tr` over email and we confirmed that `peer_cred` here should be flagged on `nto` targets. This should enable the clean `x.py --stage 2 dist rust-std` command on these platforms.
various clippy fixes
We need to keep the order of the given clippy lint rules before passing them.
Since clap doesn't offer any useful interface for this purpose out of the box,
we have to handle it manually.
Additionally, this PR makes `-D` rules work as expected. Previously, lint rules were limited to `-W`. By enabling `-D`, clippy began to complain numerous lines in the tree, all of which have been resolved in this PR as well.
Fixes#121481
cc `@matthiaskrgr`
Makes the iterator 2*usize larger, but I doubt that matters much.
In exchange, we save a lot on instruction count.
In the absence of delegation syntax,
we must forward all the specialized impls manually…
Stabilize associated type bounds (RFC 2289)
This PR stabilizes associated type bounds, which were laid out in [RFC 2289]. This gives us a shorthand to express nested type bounds that would otherwise need to be expressed with nested `impl Trait` or broken into several `where` clauses.
### What are we stabilizing?
We're stabilizing the associated item bounds syntax, which allows us to put bounds in associated type position within other bounds, i.e. `T: Trait<Assoc: Bounds...>`. See [RFC 2289] for motivation.
In all position, the associated type bound syntax expands into a set of two (or more) bounds, and never anything else (see "How does this differ[...]" section for more info).
Associated type bounds are stabilized in four positions:
* **`where` clauses (and APIT)** - This is equivalent to breaking up the bound into two (or more) `where` clauses. For example, `where T: Trait<Assoc: Bound>` is equivalent to `where T: Trait, <T as Trait>::Assoc: Bound`.
* **Supertraits** - Similar to above, `trait CopyIterator: Iterator<Item: Copy> {}`. This is almost equivalent to breaking up the bound into two (or more) `where` clauses; however, the bound on the associated item is implied whenever the trait is used. See #112573/#112629.
* **Associated type item bounds** - This allows constraining the *nested* rigid projections that are associated with a trait's associated types. e.g. `trait Trait { type Assoc: Trait2<Assoc2: Copy>; }`.
* **opaque item bounds (RPIT, TAIT)** - This allows constraining associated types that are associated with the opaque without having to *name* the opaque. For example, `impl Iterator<Item: Copy>` defines an iterator whose item is `Copy` without having to actually name that item bound.
The latter three are not expressible in surface Rust (though for associated type item bounds, this will change in #120752, which I don't believe should block this PR), so this does represent a slight expansion of what can be expressed in trait bounds.
### How does this differ from the RFC?
Compared to the RFC, the current implementation *always* desugars associated type bounds to sets of `ty::Clause`s internally. Specifically, it does *not* introduce a position-dependent desugaring as laid out in [RFC 2289], and in particular:
* It does *not* desugar to anonymous associated items in associated type item bounds.
* It does *not* desugar to nested RPITs in RPIT bounds, nor nested TAITs in TAIT bounds.
This position-dependent desugaring laid out in the RFC existed simply to side-step limitations of the trait solver, which have mostly been fixed in #120584. The desugaring laid out in the RFC also added unnecessary complication to the design of the feature, and introduces its own limitations to, for example:
* Conditionally lowering to nested `impl Trait` in certain positions such as RPIT and TAIT means that we inherit the limitations of RPIT/TAIT, namely lack of support for higher-ranked opaque inference. See this code example: https://github.com/rust-lang/rust/pull/120752#issuecomment-1979412531.
* Introducing anonymous associated types makes traits no longer object safe, since anonymous associated types are not nameable, and all associated types must be named in `dyn` types.
This last point motivates why this PR is *not* stabilizing support for associated type bounds in `dyn` types, e.g, `dyn Assoc<Item: Bound>`. Why? Because `dyn` types need to have *concrete* types for all associated items, this would necessitate a distinct lowering for associated type bounds, which seems both complicated and unnecessary compared to just requiring the user to write `impl Trait` themselves. See #120719.
### Implementation history:
Limited to the significant behavioral changes and fixes and relevant PRs, ping me if I left something out--
* #57428
* #108063
* #110512
* #112629
* #120719
* #120584Closes#52662
[RFC 2289]: https://rust-lang.github.io/rfcs/2289-associated-type-bounds.html
core: document default attribute stabilization
As of now, the first release which stabilized the `#[default]` macro for the deriving the `Default` trait for enus is not documented.
I have had to search the [`RELEASES.md`](https://github.com/rust-lang/rust/blob/master/RELEASES.md) when making sure my code would be accepted by an older Rust compiler.
I just added a line in the doc comment since, as far as I know, there's no option to pass to the `#[stable()]` attribute.
I am open to improvements in the wording.
Making `libcore` decide this is silly; the backend has so much better information about when it's a good idea.
So introduce a new `typed_swap` intrinsic with a fallback body, but replace that implementation for immediates and scalar pairs.
Add as_(mut_)ptr and as_(mut_)slice to raw array pointers
Hey, first time contributing to the standard libraries so not completely sure about the process.
These functions are complementary to the ones being added in #74265 . I found them missing on array pointers.
See also:
- ACP: https://github.com/rust-lang/libs-team/issues/321
- Tracking issue: #119834
Optimize `ptr::replace`
#83022 optimized `mem::replace` to reduce the number of `memcpy`s. `ptr::replace`, which is [documented to behave just like `mem::replace`](https://doc.rust-lang.org/nightly/std/ptr/fn.replace.html), was not optimized however, leading to [worse code](https://godbolt.org/z/T3hdEEdfe) and missed optimizations. This PR simply forwards `ptr::replace` to `mem::replace` to take advantage of the better implementation.
Use `UnsafeCell` for fast constant thread locals
This uses `UnsafeCell` instead of `static mut` for fast constant thread locals. This changes the type of the TLS shims to return `&UnsafeCell<T>` instead of `*mut T` which means they are always non-null so LLVM can optimize away the check for `Some` in `LocalKey::with` if `T` has no destructor.
LLVM is currently unable to do this optimization as we lose the fact that `__getit` always returns `Some` as it gets optimized to just returning the value of the TLS shim.
Bump windows-bindgen to 0.55.0
windows-bindgen is the crate used to generate std's Windows API bindings.
Not many changes for us, it's mostly just simplifying the generate code (e.g. no more `-> ()`). The one substantial change is some structs now use `i8` byte arrays instead of `u8`. However, this only impacts one test.
Mention labelled blocks in `break` docs
`break` doesn't require a loop, so note this in the docs. This is covered in the linked sections of the rust reference, but this page implied that `break` is only for loops.
`break` doesn't require a loop, so note this in the docs.
This is covered in the linked sections of the rust reference,
but this page implied that `break` is only for loops.
Cursor.rs documentation fix
Reason:
I've been learning Rust std library and got confused. Seek trait documentation clearly states that negative indexes will cause an error. And the code in the Cursor example uses negative index. I found myself trying to understand what am I missing until I've actually executed the code and got error. I decided to submit small fix to the documentation.
Rollup of 10 pull requests
Successful merges:
- #117118 ([AIX] Remove AixLinker's debuginfo() implementation)
- #121650 (change std::process to drop supplementary groups based on CAP_SETGID)
- #121764 (Make incremental sessions identity no longer depend on the crate names provided by source code)
- #122212 (Copy byval argument to alloca if alignment is insufficient)
- #122322 (coverage: Initial support for branch coverage instrumentation)
- #122373 (Fix the conflict problem between the diagnostics fixes of lint `unnecessary_qualification` and `unused_imports`)
- #122479 (Implement `Duration::as_millis_{f64,f32}`)
- #122487 (Rename `StmtKind::Local` variant into `StmtKind::Let`)
- #122498 (Update version of cc crate)
- #122503 (Make `SubdiagMessageOp` well-formed)
r? `@ghost`
`@rustbot` modify labels: rollup
Update version of cc crate
Reason:
In order to build the Windows version of the Rust toolchain for the Android platform, the following patch to the cc is crate is required to avoid incorrectly determining that we are building with the Android NDK: 57853c4bf8
This patch is present in version 1.0.80 and newer versions of the cc crate. The rustc source distribution currently has 3 different versions of cc in the vendor directory, only one of which has the necessary fix.
We (the Android Rust toolchain) are currently maintaining local patches to upgrade the cc crate dependency versions, which we would like to upstream.
Implement `Duration::as_millis_{f64,f32}`
Implementation of #122451.
Linked const-unstability to #72440, so the post there should probably be updated to mentions the 2 new methods when/if this PR is merged.
change std::process to drop supplementary groups based on CAP_SETGID
A trivial rebase of #95982
Should fix#39186 (from what I can tell)
Original description:
> Fixes#88716
>
> * Before this change, when a process was given a uid via `std::os::unix::process::CommandExt.uid`, there would be a `setgroups` call (when the process runs) to clear supplementary groups for the child **if the parent was root** (to remove potentially unwanted permissions).
> * After this change, supplementary groups are cleared if we have permission to do so, that is, if we have the CAP_SETGID capability.
>
> This new behavior was agreed upon in #88716 but there was a bit of uncertainty from `@Amanieu` here: [#88716 (comment)](https://github.com/rust-lang/rust/issues/88716#issuecomment-973366600)
>
> > I agree with this change, but is it really necessary to ignore an EPERM from setgroups? If you have permissions to change UID then you should also have permissions to change groups. I would feel more comfortable if we documented set_uid as requiring both UID and GID changing permissions.
>
> The way I've currently written it, we ignore an EPERM as that's what #88716 originally suggested. I'm not at all an expert in any of this so I'd appreciate feedback on whether that was the right way to go.
