Rollup of 7 pull requests
Successful merges:
- #91587 (core::ops::unsize: improve docs for DispatchFromDyn)
- #91907 (Allow `_` as the length of array types and repeat expressions)
- #92515 (RustWrapper: adapt for an LLVM API change)
- #92516 (Do not use deprecated -Zsymbol-mangling-version in bootstrap)
- #92530 (Move `contains` method of Option and Result lower in docs)
- #92546 (Update books)
- #92551 (rename StackPopClean::None to Root)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Move `contains` method of Option and Result lower in docs
Follow-up to #92444 trying to get the `Option` and `Result` rustdocs in better shape.
This addresses the request in https://github.com/rust-lang/rust/issues/62358#issuecomment-645676285. The `contains` methods are previously too high up in the docs on both `Option` and `Result` — stuff like `ok` and `map` and `and_then` should all be featured higher than `contains`. All of those are more ubiquitously useful than `contains`.
intra-doc: Make `Receiver::into_iter` into a clickable link
The documentation on `std::sync::mpsc::Iter` and `std::sync::mpsc::TryIter` provides links to the corresponding `Receiver` methods, unlike `std::sync::mpsc::IntoIter` does.
This was left out in c59b188aae
Related to #29377
Modifications to `std::io::Stdin` on Windows so that there is no longer a 4-byte buffer minimum in read().
This is an attempted fix of issue #91722, where a too-small buffer was passed to the read function of stdio on Windows. This caused an error to be returned when `read_to_end` or `read_to_string` were called. Both delegate to `std::io::default_read_to_end`, which creates a buffer that is of length >0, and forwards it to `std::io::Stdin::read()`. The latter method returns an error if the length of the buffer is less than 4, as there might not be enough space to allocate a UTF-16 character. This creates a problem when the buffer length is in `0 < N < 4`, causing the bug.
The current modification creates an internal buffer, much like the one used for the write functions
I'd also like to acknowledge the help of ``@agausmann`` and ``@hkratz`` in detecting and isolating the bug, and for suggestions that made the fix possible.
Couple disclaimers:
- Firstly, I didn't know where to put code to replicate the bug found in the issue. It would probably be wise to add that case to the testing suite, but I'm afraid that I don't know _where_ that test should be added.
- Secondly, the code is fairly fundamental to IO operations, so my fears are that this may cause some undesired side effects ~or performance loss in benchmarks.~ The testing suite runs on my computer, and it does fix the issue noted in #91722.
- Thirdly, I left the "surrogate" field in the Stdin struct, but from a cursory glance, it seems to be serving the same purpose for other functions. Perhaps merging the two would be appropriate.
Finally, this is my first pull request to the rust language, and as such some things may be weird/unidiomatic/plain out bad. If there are any obvious improvements I could do to the code, or any other suggestions, I would appreciate them.
Edit: Closes#91722
It now panic!()s on its own, rather than resume_unwind'ing the panic
payload from the thread. Using resume_unwind skips the panic_handler,
meaning that the main thread would never have a panic handler run, which
can get confusing.
- Do not `#[doc(hidden)]` the `#[derive]` macro attribute
- Add a link to the reference section to `derive`'s inherent docs
- Do the same for `#[test]` and `#[global_allocator]`
- Fix `GlobalAlloc` link (why is it on `core` and not `alloc`?)
- Try `no_inline`-ing the `std` reexports from `core`
- Revert "Try `no_inline`-ing the `std` reexports from `core`"
- Address PR review
- Also document the unstable macros
The documentation on `std::sync::mpsc::Iter` and `std::sync::mpsc::TryIter` provides links to the corresponding `Receiver` methods, unlike `std::sync::mpsc::IntoIter` does.
This was left out in c59b188aae
Related to #29377
Consolidate Result's and Option's methods into fewer impl blocks
`Result`'s and `Option`'s methods have historically been separated up into `impl` blocks based on their trait bounds, with the bounds specified on type parameters of the impl block. I find this unhelpful because closely related methods, like `unwrap_or` and `unwrap_or_default`, end up disproportionately far apart in source code and rustdocs:
<pre>
impl<T> Option<T> {
pub fn unwrap_or(self, default: T) -> T {
...
}
<img alt="one eternity later" src="https://user-images.githubusercontent.com/1940490/147780325-ad4e01a4-c971-436e-bdf4-e755f2d35f15.jpg" width="750">
}
impl<T: Default> Option<T> {
pub fn unwrap_or_default(self) -> T {
...
}
}
</pre>
I'd prefer for method to be in as few impl blocks as possible, with the most logical grouping within each impl block. Any bounds needed can be written as `where` clauses on the method instead:
```rust
impl<T> Option<T> {
pub fn unwrap_or(self, default: T) -> T {
...
}
pub fn unwrap_or_default(self) -> T
where
T: Default,
{
...
}
}
```
*Warning: the end-to-end diff of this PR is computed confusingly by git / rendered confusingly by GitHub; it's practically impossible to review that way. I've broken the PR into commits that move small groups of methods for which git behaves better — these each should be easily individually reviewable.*
Track caller of slice split and swap
Improves error location for `slice.split_at*()` and `slice.swap()`.
These are generic inline functions, so the `#[track_caller]` on them is free — only changes a value of an argument already passed to panicking code.
Rollup of 7 pull requests
Successful merges:
- #84083 (Clarify the guarantees that ThreadId does and doesn't make.)
- #91593 (Remove unnecessary bounds for some Hash{Map,Set} methods)
- #92297 (Reduce compile time of rustbuild)
- #92332 (Add test for where clause order)
- #92438 (Enforce formatting for rustc_codegen_cranelift)
- #92463 (Remove pronunciation guide from Vec<T>)
- #92468 (Emit an error for `--cfg=)`)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Remove unnecessary bounds for some Hash{Map,Set} methods
This PR moves `HashMap::{into_keys,into_values,retain}` and `HashSet::retain` from `impl` blocks with `K: Eq + Hash, S: BuildHasher` into the blocks without them. It doesn't seem to me there is any reason these methods need to be bounded by that. This change brings `HashMap::{into_keys,into_values}` on par with `HashMap::{keys,values,values_mut}` which are not bounded either.
Clarify the guarantees that ThreadId does and doesn't make.
The existing documentation does not spell out whether `ThreadId`s are unique during the lifetime of a thread or of a process. I had to examine the source code to realise (pleasingly!) that they're unique for the lifetime of a process. That seems worth documenting clearly, as it's a strong guarantee.
Examining the way `ThreadId`s are created also made me realise that the `as_u64` method on `ThreadId` could be a trap for the unwary on those platforms where the platform's notion of a thread identifier is also a 64 bit integer (particularly if they happen to use a similar identifier scheme to `ThreadId`). I therefore think it's worth being even clearer that there's no relationship between the two.
Remove CommandEnv::apply
It's not being used and uses unsound set_var and remove_var functions. This is an internal function that isn't exported (even with `process_internals` feature), so this shouldn't break anything.
Also see #92365. Note that this isn't the only use of those methods in standard library, so that particular pull request will need more changes than just this to work (in particular, `test_capture_env_at_spawn` is using `set_var` and `remove_var`).
Implement split_at_spare_mut without Deref to a slice so that the spare slice is valid
~I'm not sure I understand what's going on here correctly. And I'm pretty sure this safety comment needs to be changed. I'm just referring to the same thing that `as_mut_ptr_range` does.~ (Thanks `@RalfJung` for the guidance and clearing things up)
I tried to run https://github.com/rust-lang/miri-test-libstd on alloc with -Zmiri-track-raw-pointers, and got a failure on the test `vec::test_extend_from_within`.
I minimized the test failure into this program:
```rust
#![feature(vec_split_at_spare)]
fn main() {
Vec::<i32>::with_capacity(1).split_at_spare_mut();
}
```
The problem is that the existing implementation is actually getting a pointer range where both pointers are derived from the initialized region of the Vec's allocation, but we need the second one to be valid for the region between len and capacity. (thanks Ralf for clearing this up)
Add try_reserve and try_reserve_exact for OsString
Add `try_reserve` and `try_reserve_exact` for OsString.
Part of https://github.com/rust-lang/rust/issues/91789
I will squash the commits after PR is ready to merge.
Signed-off-by: Xuanwo <github@xuanwo.io>
It appears `find_max_slow` comes from the BinaryHeap docs, where the
try_reserve example is a slow implementation of find_max. It has no
relevance to this code in OsString though.
The crate name is already set in Cargo.toml. The comment says there is
some logic in the compiler that reads #![crate_name] and not
--crate-name, but I can't find it. Removing it seems to work fine.
Remove `maybe_uninit_extra` feature from Vec docs
In `Vec`, two doc tests are using `MaybeUninit::write` , stabilized in 1.55. This makes docs' usage of `maybe_uninit_extra` feature unnecessary.
Old code already contain optimization for cases with `&str` and `&[u8]` args. This commit adds a specialization for `&mut[u8]` too.
Also, I added usage of old slice in search for zero bytes instead of new buffer because it produce better code for Windows on LTO builds. For other platforms, this wouldn't cause any difference because it calls `libc` anyway.
Inlined `_new` method into spec trait to reduce amount of code generated to `CString::new` callers.
Add `#[inline]` modifier to `TypeId::of`
It was already inlined but it happened only in 4th InlinerPass on my testcase.
With `#[inline]` modifier it happens on 2nd pass.
Closes#74362
RawVec: don't recompute capacity after allocating.
Currently it sets the capacity to `ptr.len() / mem::size_of::<T>()`
after any buffer allocation/reallocation. This would be useful if
allocators ever returned a `NonNull<[u8]>` with a size larger than
requested. But this never happens, so it's not useful.
Removing this slightly reduces the size of generated LLVM IR, and
slightly speeds up the hot path of `RawVec` growth.
r? `@ghost`
disable test with self-referential generator on Miri
Running the libcore test suite in Miri currently fails due to the known incompatibility of self-referential generators with Miri's aliasing checks (https://github.com/rust-lang/unsafe-code-guidelines/issues/148). So let's disable that test in Miri for now.
Use panic() instead of panic!() in some places in core.
See https://github.com/rust-lang/rust/pull/92068 and https://github.com/rust-lang/rust/pull/92140.
This avoids the `panic!()` macro in a few potentially hot paths. This becomes more relevant when switching `core` to Rust 2021, as it'll avoid format_args!() and save some compilation time. (It doesn't make a huge difference, but still.) (Also the errors in const panic become slightly nicer.)
Quote bat script command line
Fixes#91991
[`CreateProcessW`](https://docs.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-createprocessw#parameters) should only be used to run exe files but it does have some (undocumented) special handling for files with `.bat` and `.cmd` extensions. Essentially those magic extensions will cause the parameters to be automatically rewritten. Example pseudo Rust code (note that `CreateProcess` starts with an optional application name followed by the application arguments):
```rust
// These arguments...
CreateProcess(None, `@"foo.bat` "hello world""`@,` ...);
// ...are rewritten as
CreateProcess(Some(r"C:\Windows\System32\cmd.exe"), `@""foo.bat` "hello world"""`@,` ...);
```
However, when setting the first parameter (the application name) as we now do, it will omit the extra level of quotes around the arguments:
```rust
// These arguments...
CreateProcess(Some("foo.bat"), `@"foo.bat` "hello world""`@,` ...);
// ...are rewritten as
CreateProcess(Some(r"C:\Windows\System32\cmd.exe"), `@"foo.bat` "hello world""`@,` ...);
```
This means the arguments won't be passed to the script as intended.
Note that running batch files this way is undocumented but people have relied on this so we probably shouldn't break it.
Change Backtrace::enabled atomic from SeqCst to Relaxed
This atomic is not synchronizing anything outside of its own value, so we don't need the `Acquire`/`Release` guarantee that all memory operations prior to the store are visible after the subsequent load, nor the `SeqCst` guarantee of all threads seeing all of the sequentially consistent operations in the same order.
Using `Relaxed` reduces the overhead of `Backtrace::capture()` in the case that backtraces are not enabled.
## Benchmark
```rust
#![feature(backtrace)]
use std::backtrace::Backtrace;
use std::sync::atomic::{AtomicUsize, Ordering};
use std::thread;
use std::time::Instant;
fn main() {
let begin = Instant::now();
let mut threads = Vec::new();
for _ in 0..64 {
threads.push(thread::spawn(|| {
for _ in 0..10_000_000 {
let _ = Backtrace::capture();
static LOL: AtomicUsize = AtomicUsize::new(0);
LOL.store(1, Ordering::Release);
}
}));
}
for thread in threads {
let _ = thread.join();
}
println!("{:?}", begin.elapsed());
}
```
**Before:** 6.73 seconds
**After:** 5.18 seconds
Allow reverse iteration of lowercase'd/uppercase'd chars
The PR implements `DoubleEndedIterator` trait for `ToLowercase` and `ToUppercase`.
This enables reverse iteration of lowercase/uppercase variants of character sequences.
One of use cases: determining whether a char sequence is a suffix of another one.
Example:
```rust
fn endswith_ignore_case(s1: &str, s2: &str) -> bool {
for eob in s1
.chars()
.flat_map(|c| c.to_lowercase())
.rev()
.zip_longest(s2.chars().flat_map(|c| c.to_lowercase()).rev())
{
match eob {
EitherOrBoth::Both(c1, c2) => {
if c1 != c2 {
return false;
}
}
EitherOrBoth::Left(_) => return true,
EitherOrBoth::Right(_) => return false,
}
}
true
}
```
Currently it sets the capacity to `ptr.len() / mem::size_of::<T>()`
after any buffer allocation/reallocation. This would be useful if
allocators ever returned a `NonNull<[u8]>` with a size larger than
requested. But this never happens, so it's not useful.
Removing this slightly reduces the size of generated LLVM IR, and
slightly speeds up the hot path of `RawVec` growth.
The previous implementation used slice::as_mut_ptr_range to derive the
pointer for the spare capacity slice. This is invalid, because that
pointer is derived from the initialized region, so it does not have
provenance over the uninitialized region.
Update example code for Vec::splice to change the length
The current example for `Vec::splice` illustrates the replacement of a section of length 2 with a new section of length 2. This isn't a particularly interesting case for splice, and makes it look a bit like a shorthand for the kind of manipulations that could be done with a mutable slice.
In order to provide a stronger example, this updates the example to use different lengths for the source and destination regions, and uses a slice from the middle of the vector to illustrate that this does not necessarily have to be at the beginning or the end.
Resolves#92067
Revert "Temporarily rename int_roundings functions to avoid conflicts"
This reverts commit 3ece63b64e.
This should be okay because #90329 has been merged.
r? `@joshtriplett`
The src pointers in CopyOnDrop and InsertionHole used to be *mut T, and
were derived via automatic conversion from &mut T. According to Stacked
Borrows 2.1, this means that those pointers become invalidated by
interior mutation in the comparison function.
But there's no need for mutability in this code path. Thus, we can
change the drop guards to use *const and derive those from &T.
Add a space and 2 grave accents
I only noticed this because I have this implementation copy pasted in some places in my code and I really can't wait for this to be stabilized...
Update stdlib to the 2021 edition
progress towards https://github.com/rust-lang/rust/issues/88638
I couldnt find a way to run the 2018 style panic tests against 2018 so I just deleted them, maybe theres a way to do it that I missed though?
Mark defaulted `PartialEq`/`PartialOrd` methods as const
WIthout it, `const` impls of these traits are unpleasant to write. I think this kind of change is allowed now. although it looks like it might require some Miri tweaks. Let's find out.
r? ```@fee1-dead```
Do array-slice equality via array equality, rather than always via slices
~~Draft because it needs a rebase after #91766 eventually gets through bors.~~
This enables the optimizations from #85828 to be used for array-to-slice comparisons too, not just array-to-array.
For example, <https://play.rust-lang.org/?version=nightly&mode=release&edition=2021&gist=5f9ba69b3d5825a782f897c830d3a6aa>
```rust
pub fn demo(x: &[u8], y: [u8; 4]) -> bool {
*x == y
}
```
Currently writes the array to stack for no reason:
```nasm
sub rsp, 4
mov dword ptr [rsp], edx
cmp rsi, 4
jne .LBB0_1
mov eax, dword ptr [rdi]
cmp eax, dword ptr [rsp]
sete al
add rsp, 4
ret
.LBB0_1:
xor eax, eax
add rsp, 4
ret
```
Whereas with the change in this PR it just compares it directly:
```nasm
cmp rsi, 4
jne .LBB1_1
cmp dword ptr [rdi], edx
sete al
ret
.LBB1_1:
xor eax, eax
ret
```
Add `io::Error::other`
This PR adds a small utility constructor, `io::Error::other`, a shorthand for `io::Error::new(io::ErrorKind::Other, err)`, something I find myself writing often.
For some concrete stats, a quick search on [grep.app](https://grep.app) shows that more than half of the uses of `io::Error::new` use `ErrorKind::Other`:
```
Error::new\((?:std::)?(?:io::)?ErrorKind:: => 3,898 results
Error::new\((?:std::)?(?:io::)?ErrorKind::Other => 2,186 results
```
Most of these problems originate in use of get_unchecked_mut.
When calling ptr::copy_nonoverlapping, using get_unchecked_mut for both
arguments causes the borrow created to make the second pointer to invalid the
first.
The pairs of identical MaybeUninit::slice_as_mut_ptr calls similarly
invalidate each other.
There was also a similar borrow invalidation problem with the use of
slice::get_unchecked_mut to derive the pointer for the CopyOnDrop.
link to pref_align_of tracking issue
If we are not going to remove this intrinsic (https://github.com/rust-lang/rust/pull/90877), I think we should at least have a place to centralize discussion around it, so here we go. Intrinsics don't have their own separate features and usually we instead use the public method for tracking it, but this one does not have such a method... so the tracking issue is just a regular link. (And then we sue it for the const part as well.)
update stdarch
2 commits in d219ad63c5075098fc224a57deb4852b9734327d..0716b22e902207efabe46879cbf28d0189ab7924
2021-12-9 23:50:37 +0000 to 2021-12-14 16:17:57 +0100
* Fix a bunch of typos ([Fix a bunch of typos stdarch#1267](https://github.com/rust-lang/stdarch/pull/1267))
* Stabilize armv8 neon instruction set on aarch64 ([Stabilize armv8 neon instruction set on aarch64 stdarch#1266](https://github.com/rust-lang/stdarch/pull/1266))
The update stabilizes armv8 neon instructions on aarch64. #90972
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.
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.
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.
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).
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.
Stabilize asm! and global_asm!
Tracking issue: #72016
It's been almost 2 years since the original [RFC](https://github.com/rust-lang/rfcs/pull/2850) was posted and we're finally ready to stabilize this feature!
The main changes in this PR are:
- Removing `asm!` and `global_asm!` from the prelude as per the decision in #87228.
- Stabilizing the `asm` and `global_asm` features.
- Removing the unstable book pages for `asm` and `global_asm`. The contents are moved to the [reference](https://github.com/rust-lang/reference/pull/1105) and [rust by example](https://github.com/rust-lang/rust-by-example/pull/1483).
- All links to these pages have been removed to satisfy the link checker. In a later PR these will be replaced with links to the reference or rust by example.
- Removing the automatic suggestion for using `llvm_asm!` instead of `asm!` if you're still using the old syntax, since it doesn't work anymore with `asm!` no longer being in the prelude. This only affects code that predates the old LLVM-style `asm!` being renamed to `llvm_asm!`.
- Updating `stdarch` and `compiler-builtins`.
- Updating all the tests.
r? `@joshtriplett`
This'll still go via slices eventually for large arrays, but this way slice comparisons to short arrays can use the same memcmp-avoidance tricks.
Added some tests for all the combinations to make sure I didn't accidentally infinitely-recurse something.
Make split_inclusive() on an empty slice yield an empty output
`[].split_inclusive()` currently yields a single, empty slice. That's
different from `"".split_inslusive()`, which yields no output at
all. I think that makes the slice version harder to use.
The case where I ran into this bug was when writing code for
generating a diff between two slices of bytes. I wanted to prefix
removed lines with "-" and a added lines with "+". Due to
`split_inclusive()`'s current behavior, that means that my code prints
just a "-" or "+" for empty files. I suspect most existing callers
have similar "bugs" (which would be fixed by this patch).
Closes#89716.
add BinaryHeap::try_reserve and BinaryHeap::try_reserve_exact
`try_reserve` of many collections were stablized in https://github.com/rust-lang/rust/pull/87993 in 1.57.0. Add `try_reserve` for the rest collections such as `BinaryHeap` should be not controversial.
Use spare_capacity_mut instead of invalid unchecked indexing when joining str
This is a fix for https://github.com/rust-lang/rust/issues/91574
I think in general I'd prefer to see this code implemented with raw pointers or `MaybeUninit::write_slice`, but there's existing code in here based on copying from slice to slice, so converting everything from `&[T]` to `&[MaybeUninit<T>]` is less disruptive.
BTree: improve public descriptions and comments
BTreeSet has always used the term "value" next to and meaning the same thing as "elements" (in the mathematical sense but also used for key-value pairs in BTreeMap), while in the BTreeMap sense these "values" are known as "keys" and definitely not "values". Today I had enough of that.
r? `@Mark-Simulacrum`
Stabilize `ControlFlow::{is_break, is_continue}`
The type itself was stabilized in 1.55, but using it is not ergonomic without these helper functions. Stabilize them.
r? rust-lang/libs-api
They are also removed from the prelude as per the decision in
https://github.com/rust-lang/rust/issues/87228.
stdarch and compiler-builtins are updated to work with the new, stable
asm! and global_asm! macros.
Btree: assert more API compatibility
Introducing a member such as `BTreeSet::min()` would silently break compatibility if no code calls the existing `BTreeSet::min(set)`. `BTreeSet` is the only btree class silently bringing in stable members, apart from many occurrences of `#[derive(Debug)]` on iterators.
r? `@Mark-Simulacrum`
Make certain panicky stdlib functions behave better under panic_immediate_abort
The stdlib has a `panic_immediate_abort` feature that turns panics into immediate aborts, without any formatting/display logic. This feature was [introduced](https://github.com/rust-lang/rust/pull/55011) primarily for codesize-constrained situations.
Unfortunately, this win doesn't quite propagate to `Result::expect()` and `Result::unwrap()`, while the formatting machinery is reduced, `expect()` and `unwrap()` both call `unwrap_failed("msg", &err)` which has a signature of `fn unwrap_failed(msg: &str, error: &dyn fmt::Debug)` and is `#[inline(never)]`. This means that `unwrap_failed` will unconditionally construct a `dyn Debug` trait object even though the object is never used in the function.
Constructing a trait object (even if you never call a method on it!) forces rust to include the vtable and any dependencies. This means that in `panic_immediate_abort` mode, calling expect/unwrap on a Result will pull in a whole bunch of formatting code for the error type even if it's completely unused.
This PR swaps out the function with one that won't require a trait object such that it won't force the inclusion of vtables in the code. It also gates off `#[inline(never)]` in a bunch of other places where allowing the inlining of an abort may be useful (this kind of thing is already done elsewhere in the stdlib).
I don't know how to write a test for this; we don't really seem to have any tests for `panic_immediate_abort` anyway so perhaps it's fine as is.
Minor improvements to `future::join!`'s implementation
This is a follow-up from #91645, regarding [some remarks I made](https://rust-lang.zulipchat.com/#narrow/stream/187312-wg-async-foundations/topic/join!/near/264293660).
Mainly:
- it hides the recursive munching through a private `macro`, to avoid leaking such details (a corollary is getting rid of the need to use ``@`` to disambiguate);
- it uses a `match` binding, _outside_ the `async move` block, to better match the semantics from function-like syntax;
- it pre-pins the future before calling into `poll_fn`, since `poll_fn`, alone, cannot guarantee that its capture does not move (to clarify: I believe the previous code was sound, thanks to the outer layer of `async`. But I find it clearer / more robust to refactorings this way 🙂).
- it uses `@ibraheemdev's` very neat `.ready()?`;
- it renames `Took` to `Taken` for consistency with `Done` (tiny nit 😄).
~~TODO~~Done:
- [x] Add unit tests to enforce the function-like `:value` semantics are respected.
r? `@nrc`
Add spin_loop hint for RISC-V architecture
This commit uses the PAUSE instruction (https://github.com/rust-lang/stdarch/pull/1262) to implement RISC-V spin loop, and updates `stdarch` submodule to use the merged PAUSE instruction.
Rollup of 11 pull requests
Successful merges:
- #91668 (Remove the match on `ErrorKind::Other`)
- #91678 (Add tests fixed by #90023)
- #91679 (Move core/stream/stream/mod.rs to core/stream/stream.rs)
- #91681 (fix typo in `intrinsics::raw_eq` docs)
- #91686 (Fix `Vec::reserve_exact` documentation)
- #91697 (Delete Utf8Lossy::from_str)
- #91706 (Add unstable book entries for parts of asm that are not being stabilized)
- #91709 (Replace iterator-based set construction by *Set::From<[T; N]>)
- #91716 (Improve x.py logging and defaults a bit more)
- #91747 (Add pierwill to .mailmap)
- #91755 (Fix since attribute for const_linked_list_new feature)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Replace iterator-based set construction by *Set::From<[T; N]>
This uses the array-based construction for `BtreeSet`s and `HashSet`s instead of first creating an iterator. I could also replace the `let mut a = Set::new(); a.insert(...);` fragments if desired.
Delete Utf8Lossy::from_str
This whole type is marked as being for str internals only, but this constructor is never used by str internals. If you had a &str already and wanted to lossy display it or iterate its lossy utf8 chunks, you would simply not use Utf8Lossy because the whole &str is known to be one contiguous valid utf8 chunk.
If code really does need to obtain a value of type &Utf8Lossy somewhere, and has only a &str, `Utf8Lossy::from_bytes(s.as_bytes())` remains available. As currently implemented, there is no performance penalty relative to `from_str` i.e. the Utf8Lossy does not "remember" that it was constructed using `from_str` to bypass later utf8 decoding.
Fix `Vec::reserve_exact` documentation
The documentation previously said the new capacity cannot overflow `usize`, but in fact it cannot exceed `isize::MAX`.
Update documentation to use `from()` to initialize `HashMap`s and `BTreeMap`s
As of Rust 1.56, `HashMap` and `BTreeMap` both have associated `from()` functions. I think using these in the documentation cleans things up a bit. It allows us to remove some of the `mut`s and avoids the Initialize-Then-Modify anti-pattern.
adjust const_eval_select documentation
"The Rust compiler assumes" indicates that this is language UB, but [I don't think that is a good idea](https://rust-lang.zulipchat.com/#narrow/stream/146212-t-compiler.2Fconst-eval/topic/const_eval_select.20assumptions). This UB would be very hard to test for and looks like a way-too-big footgun. ``@oli-obk`` suggested this is meant to be more like "library UB", so I tried to adjust the docs accordingly.
I also removed all references to "referential transparency". That is a rather vague concept used to mean many different things, and I honestly have no idea what exactly is meant by it in this specific instance. But I assume ``@fee1-dead`` had in their mind a property that all `const fn` code upholds, so by demanding that the runtime code and the const-time code are *observably equivalent*, whatever that property is would also be enforced here.
Cc ``@rust-lang/wg-const-eval``
Fix incorrect stability attributes
These two instances were caught in #90356, but that PR isn't going to be merged. I've extracted these to ensure it's still correct.
``@rustbot`` label: +A-stability +C-cleanup +S-waiting-on-review
This is a follow-up from #91645, regarding [some remarks I made](https://rust-lang.zulipchat.com/#narrow/stream/187312-wg-async-foundations/topic/join!/near/264293660).
Mainly:
- it hides the recursive munching through a private `macro`, to avoid leaking such details (a corollary is getting rid of the need to use `@` to disambiguate);
- it uses a `match` binding, _outside_ the `async move` block, to better match the semantics from function-like syntax;
- it pre-pins the future before calling into `poll_fn`, since `poll_fn`, alone, cannot guarantee that its capture does not move;
- it uses `.ready()?` since it's such a neat pattern;
- it renames `Took` to `Taken` for consistency with `Done`.
replace vec::Drain drop loops with drop_in_place
The `Drain::drop` implementation came up in https://github.com/rust-lang/rust/pull/82185#issuecomment-789584796 as potentially interfering with other optimization work due its widespread use somewhere in `println!`
`@rustbot` label T-libs-impl
Implement most of RFC 2930, providing the ReadBuf abstraction
This replaces the `Initializer` abstraction for permitting reading into uninitialized buffers, closing #42788.
This leaves several APIs described in the RFC out of scope for the initial implementation:
* read_buf_vectored
* `ReadBufs`
Closes#42788, by removing the relevant APIs.
Rollup of 6 pull requests
Successful merges:
- #87599 (Implement concat_bytes!)
- #89999 (Update std::env::temp_dir to use GetTempPath2 on Windows when available.)
- #90796 (Remove the reg_thumb register class for asm! on ARM)
- #91042 (Use Vec extend instead of repeated pushes on several places)
- #91634 (Do not attempt to suggest help for overly malformed struct/function call)
- #91685 (Install llvm tools to sysroot when assembling local toolchain)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Update std::env::temp_dir to use GetTempPath2 on Windows when available.
As a security measure, Windows 11 introduces a new temporary directory API, GetTempPath2.
When the calling process is running as SYSTEM, a separate temporary directory
will be returned inaccessible to non-SYSTEM processes. For non-SYSTEM processes
the behavior will be the same as before.
This can help mitigate against attacks such as this one:
https://medium.com/csis-techblog/cve-2020-1088-yet-another-arbitrary-delete-eop-a00b97d8c3e2
Compatibility risk: Software which relies on temporary files to communicate between SYSTEM and non-SYSTEM
processes may be affected by this change. In many cases, such patterns may be vulnerable to the very
attacks the new API was introduced to harden against.
I'm unclear on the Rust project's tolerance for such change-of-behavior in the standard library. If anything,
this PR is meant to raise awareness of the issue and hopefully start the conversation.
How tested: Taking the example code from the documentation and running it through psexec (from SysInternals) on
Win10 and Win11.
On Win10:
C:\test>psexec -s C:\test\main.exe
<...>
Temporary directory: C:\WINDOWS\TEMP\
On Win11:
C:\test>psexec -s C:\test\main.exe
<...>
Temporary directory: C:\Windows\SystemTemp\
Implement concat_bytes!
This implements the unstable `concat_bytes!` macro, which has tracking issue #87555. It can be used like:
```rust
#![feature(concat_bytes)]
fn main() {
assert_eq!(concat_bytes!(), &[]);
assert_eq!(concat_bytes!(b'A', b"BC", [68, b'E', 70]), b"ABCDEF");
}
```
If strings or characters are used where byte strings or byte characters are required, it suggests adding a `b` prefix. If a number is used outside of an array it suggests arrayifying it. If a boolean is used it suggests replacing it with the numeric value of that number. Doubly nested arrays of bytes are disallowed.
Rollup of 7 pull requests
Successful merges:
- #83744 (Deprecate crate_type and crate_name nested inside #![cfg_attr])
- #90550 (Update certificates in some Ubuntu 16 images.)
- #91272 (Print a suggestion when comparing references to primitive types in `const fn`)
- #91467 (Emphasise that an OsStr[ing] is not necessarily a platform string)
- #91531 (Do not add `;` to expected tokens list when it's wrong)
- #91577 (Address some FIXMEs left over from #91475)
- #91638 (Remove `in_band_lifetimes` from `rustc_mir_transform`)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Emphasise that an OsStr[ing] is not necessarily a platform string
Fixes#53261
Since that issue was filed, #56141 added a further clarification to the `OsString` docs. However the ffi docs may still leave the impression that an `OsStr` is in the platform native form. This PR aims to further emphasise that an `OsStr` is not necessarily a platform string.
Sync portable-simd to remove autosplats
This PR syncs portable-simd in up to a8385522ad in order to address the type inference breakages documented on nightly in https://github.com/rust-lang/rust/issues/90904 by removing the vector + scalar binary operations (called "autosplats", "broadcasting", or "rank promotion", depending on who you ask) that allow `{scalar} + &'_ {scalar}` to fail in some cases, because it becomes possible the programmer may have meant `{scalar} + &'_ {vector}`.
A few quality-of-life improvements make their way in as well:
- Lane counts can now go to 64, as LLVM seems to have fixed their miscompilation for those.
- `{i,u}8x64` to `__m512i` is now available.
- a bunch of `#[must_use]` notes appear throughout the module.
- Some implementations, mostly instances of `impl core::ops::{Op}<Simd> for Simd` that aren't `{vector} + {vector}` (e.g. `{vector} + &'_ {vector}`), leverage some generics and `where` bounds now to make them easier to understand by reducing a dozen implementations into one (and make it possible for people to open the docs on less burly devices).
- And some internal-only improvements.
None of these changes should affect a beta backport, only actual users of `core::simd` (and most aren't even visible in the programmatic sense), though I can extract an even more minimal changeset for beta if necessary. It seemed simpler to just keep moving forward.
Suggest try_reserve in try_reserve_exact
During developing #91529 , I found that `try_reserve_exact` suggests `reserve` for further insertions. I think it's a mistake by copy&paste, `try_reserve` is better here.
