Revert adding Atomic::from_mut.
This reverts #74532, which made too many assumptions about platforms, breaking some things.
Will need to be added later with a better way of gating on proper alignment, without hardcoding cfg(target_arch)s.
---
To be merged if fixing from_mut (#76965) takes too long.
r? @ghost
Add non-`unsafe` `.get_mut()` for `Unsafecell`
- Tracking issue: https://github.com/rust-lang/rust/issues/76943
As discussed in: https://internals.rust-lang.org/t/add-non-unsafe-get-mut-for-unsafecell/12407
- ### [Rendered documentation](https://modest-dubinsky-1f9f47.netlify.app/core/cell/struct.unsafecell)
This PR tries to move the sound `&mut UnsafeCell<T> -> &mut T` projection that all the "downstream" constructions were already relying on, up to the root abstraction, where it rightfully belongs, and officially blessing it.
- this **helps reduce the amount of `unsafe` snippets out there** (_c.f._, the second commit of this PR: 09503fd1b3)
The fact that this getter is now expose for `UnsafeCell<T>` itself, will also help convey the idea that **`UnsafeCell` is not magical _w.r.t._ `&mut` accesses**, contrary to what some people incorrectly think.
- Even the standard library itself at some point had such a confusion, _c.f._ this comment where there is a mention of multi-threaded (and thus _shared_) access despite dealing with exclusive references over unique ownership: 59fb88d061/library/core/src/cell.rs (L498-L499)
r? @RalfJung
Use intra-doc links in core/src/iter when possible
Helps with #75080.
I also updated lots of links to use `fn()` instead of `fn` when possible.
@rustbot modify labels: T-doc A-intra-doc-links
r? @jyn514
Stabilize some Option methods as const
Stabilize the following methods of `Option` as const:
- `is_some`
- `is_none`
- `as_ref`
These methods are currently const under the unstable feature `const_option` (tracking issue: #67441).
I believe these methods to be eligible for stabilization because of the stabilization of #49146 (Allow if and match in constants) and the trivial implementations, see also: [PR#75463](https://github.com/rust-lang/rust/pull/75463).
Related: #76225
The libc crate is already responsible for linking in the appropriate
libraries, and std doing the same thing results in duplicated library
names on the linker command line. Removing this duplication slightly
reduces linker time, and makes it simpler to adjust the set or order of
linked libraries in one place (such as to add static linking support).
Avoid useless sift_down when std::collections::binary_heap::PeekMut is never mutably dereferenced
If `deref_mut` is never called then it's not possible for the element to be mutated without internal mutability, meaning there's no need to call `sift_down`.
This could be a little improvement in cases where you want to mutate the biggest element of the heap only if it satisfies a certain predicate that needs only read access to the element.
Remove MMX from Rust
Follow-up to https://github.com/rust-lang/stdarch/pull/890
This removes most of MMX from Rust (tests pass with small changes), keeping stable `is_x86_feature_detected!("mmx")` working.
Stabilize the following methods of `Option` as const:
- `is_some`
- `is_none`
- `as_ref`
Possible because of stabilization of #49146 (Allow if and match in constants).
Rollup of 15 pull requests
Successful merges:
- #76732 (Add docs for `BasicBlock`)
- #76832 (Let backends define custom targets)
- #76866 (Remove unused feature gates from library/ crates)
- #76875 (Move to intra-doc links in library/alloc/src/collections/binary_heap.rs)
- #76876 (Move to intra-doc links in collections/btree/map.rs and collections/linked_list.rs)
- #76877 (Move to intra-doc links in collections/vec_deque.rs and collections/vec_deque/drain.rs)
- #76878 (Move the version number to a plaintext file)
- #76883 (README.md: Remove prompts from code blocks)
- #76887 (Add missing examples on HashSet iter types)
- #76890 (use matches!() macro for simple if let conditions)
- #76891 (don't take `TyCtxt` by reference)
- #76910 (transmute: use diagnostic item)
- #76924 (Add tracking issue for feature(unix_socket_peek))
- #76926 (BTreeMap: code readability tweaks)
- #76940 (Don't allow implementing trait directly on type-alias-impl-trait)
Failed merges:
r? `@ghost`
transmute: use diagnostic item
closes#66075, we now have no remaining uses of `match_def_path` in the compiler while some uses still remain in `clippy`.
cc @RalfJung
Move to intra-doc links in collections/vec_deque.rs and collections/vec_deque/drain.rs
Helps with #75080.
@rustbot modify labels: T-doc, A-intra-doc-links
Remove unused feature gates from library/ crates
Removes some unused feature gates from library crates. It's likely not a complete list as I only tested a subset for which it's more likely that it is unused.
Stabilize some Result methods as const
Stabilize the following methods of Result as const:
- `is_ok`
- `is_err`
- `as_ref`
A test is also included, analogous to the test for `const_option`.
These methods are currently const under the unstable feature `const_result` (tracking issue: #67520).
I believe these methods to be eligible for stabilization because of the stabilization of #49146 (Allow if and match in constants) and the trivial implementations, see also: [PR#75463](https://github.com/rust-lang/rust/pull/75463) and [PR#76135](https://github.com/rust-lang/rust/pull/76135).
Note: these methods are the only methods currently under the `const_result` feature, thus this PR results in the removal of the feature.
Related: #76225
This made too many assumptions about platforms, breaking some things.
Will need to be added later with a better way of gating on proper
alignment, without hardcoding cfg(target_arch)s.
support panic=abort in Miri
This is needed for https://github.com/rust-lang/miri/issues/1058 on Windows: we cannot run the inline-assembly versions of `abort`, so fall back to the intrinsic (which Miri supports).
Test and fix Send and Sync traits of BTreeMap artefacts
Fixes#76686.
I'm not quite sure what all this implies. E.g. comparing with the definitions for `NodeRef` in node.rs, maybe an extra bound `T: 'a` is useful for something. The test compiles on stable/beta (apart from `drain_filter`) so I bet `Sync` is equally desirable.
r? @Mark-Simulacrum
BTreeMap: wrap node's raw parent pointer in NonNull
Now that the other `*const` (root) is gone, seemed like a small step forward.
r? `@Mark-Simulacrum`
Add as_str() to string::Drain.
Vec's Drain recently [had its `.as_slice()` stabilized](https://github.com/rust-lang/rust/pull/72584), but String's Drain was still missing the analogous `.as_str()`. This adds that.
Also improves the Debug implementation, which now shows the remaining data instead of just `"Drain { .. }"`.
Add associated constant `BITS` to all integer types
Recently I've regularly come across this snippet (in a few different crates, including `core` and `std`):
```rust
std::mem::size_of<usize>() * 8
```
I think it's time for a `usize::BITS`.
do not inline black_box when building for Miri
We cannot do the assembly trick in Miri, but let's at least make sure MIR inlining does not circumvent the black_box.
Also use black_box instead of local optimization barriers in a few const tests.
deny(unsafe_op_in_unsafe_fn) in libstd/path.rs
The libstd/path.rs part of #73904 . Wraps the two calls to an unsafe fn Initializer::nop() in an unsafe block.
BTreeMap: avoid slices even more
Epilogue to #73971: it seems the compiler is unable to realize that creating a slice and `get_unchecked`-ing one element is a simple fetch. So try to spell it out for the only remaining but often invoked case.
Also, the previous code doesn't seem fair game to me, using `get_unchecked` to reach beyond the end of a slice. Although the local function `slice_insert` also does that.
r? `@Mark-Simulacrum`
Small cleanups in Windows Mutex.
- Move `held` into the boxed part, since the SRW lock implementation does not use this. This makes the Mutex 50% smaller.
- Use `Cell` instead of `UnsafeCell` for `held`, such that `.replace()` can be used.
- Add some comments.
- Avoid creating multiple `&mut`s to the critical section object in `ReentrantMutex`.
[fuchsia] Propagate the userspace UTC clock
On Fuchsia, spawning a subprocess does not automatically
clone all of the parent process' capabilities. UTC time on
Fuchsia is managed by a top-level userspace clock capability
that is cloned and passed to subprocesses.
This change ensures that any Rust subprocess gets access to the
UTC clock, if the parent had access to it. This is critical for
tests, which on Fuchsia, use panic=abort and spawn subprocesses
per test.
Add array_windows fn
This mimicks the functionality added by array_chunks, and implements a const-generic form of
`windows`. It makes egregious use of `unsafe`, but by necessity because the array must be
re-interpreted as a slice of arrays, and unlike array_chunks this cannot be done by casting the
original array once, since each time the index is advanced it needs to move one element, not
`N`.
I'm planning on adding more tests, but this should be good enough as a premise for the functionality.
Notably: should there be more functions overwritten for the iterator implementation/in general?
~~I've marked the issue as #74985 as there is no corresponding exact issue for `array_windows`, but it's based of off `array_chunks`.~~
Edit: See Issue #75027 created by @lcnr for tracking issue
~~Do not merge until I add more tests, please.~~
r? @lcnr
Updated issue to #75027
Update to rm oob access
And hopefully fix docs as well
Fixed naming conflict in test
Fix test which used 1-indexing
Nth starts from 0, woops
Fix a bunch of off by 1 errors
See https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=757b311987e3fae1ca47122969acda5a
Add even more off by 1 errors
And also write `next` and `next_back` in terms of `nth` and `nth_back`.
Run fmt
Fix forgetting to change fn name in test
add nth_back test & document unsafe
Remove as_ref().unwrap()
Documented occurrences of unsafe, noting what invariants are maintained
Fix liballoc test suite for Miri
Mostly, fix the regression introduced by https://github.com/rust-lang/rust/pull/75207 that caused slices (i.e., references) to be created to invalid memory or memory that has aliasing pointers that we want to keep valid. @dylni this changes the type of `check_range` to only require the length, not the full reference to the slice, which indeed is all the information this function requires.
Also reduce the size of a test introduced in https://github.com/rust-lang/rust/pull/70793 to make it not take 3 minutes in Miri.
This makes https://github.com/RalfJung/miri-test-libstd work again.
Make all methods of `Duration` unstably const
Make the following methods of `Duration` unstable const under `duration_const_2`:
- `from_secs_f64`
- `from_secs_f32`
- `mul_f64`
- `mul_f32`
- `div_f64`
- `div_f32`
This results in all methods of `Duration` being (unstable) const.
Moved the tests to `library` as part of #76268.
Possible because of #72449, which made the relevant `f32` and `f64` methods const.
Tracking issue: #72440
r? @ecstatic-morse
Make some Ordering methods const
Resubmission of [PR#75463](https://github.com/rust-lang/rust/pull/75463) as per [PR#76172](https://github.com/rust-lang/rust/pull/76172).
Constify the following methods of `core::cmp::Ordering`:
- `reverse`
- `then`
Insta-stabilizes these methods as const under the `const_ordering` feature, as their implementation is a trivial match and the recent stabilization of #49146 (Allow `if` and `match` in constants).
Note: the `const_ordering` feature has never actually been used as these methods have not been `#[rustc_const_unstable]`.
Tracking issue: #76113
Consolidate some duplicate code in the sys modules.
This consolidates some modules which were duplicated throughout the sys module. The intent is to make it easier to update and maintain this code. This mainly affects the wasi, sgx, and "unsupported" targets.
I explicitly skipped hermit, cloudabi, and vxworks. These tier-3 targets have copied large sections of the sys tree. I don't think they should have, but I don't want to put effort into changing them. It also doesn't help that there aren't any scripts or instructions for building them.
There are still sections of duplicate code here and there, but this PR covers the easy parts where entire modules are the same.
Note when a a move/borrow error is caused by a deref coercion
Fixes#73268
When a deref coercion occurs, we may end up with a move error if the
base value has been partially moved out of. However, we do not indicate
anywhere that a deref coercion is occuring, resulting in an error
message with a confusing span.
This PR adds an explicit note to move errors when a deref coercion is
involved. We mention the name of the type that the deref-coercion
resolved to, as well as the `Deref::Target` associated type being used.
Detect overflow in proc_macro_server subspan
* Detect overflow in proc_macro_server subspan
* Add tests for overflow in Vec::drain
* Add tests for overflow in String / VecDeque operations using ranges
deny(unsafe_op_in_unsafe_fn) in libstd/process.rs
The libstd/process.rs part of #73904 . Wraps the two calls to an unsafe fn Initializer::nop() in an unsafe block.
Will have to wait for #73909 to be merged, because of the feature in the libstd/lib.rs
On Fuchsia, spawning a subprocess does not automatically
clone all of the parent process' capabilities. UTC time on
Fuchsia is managed by a top-level userspace clock capability
that is cloned and passed to subprocesses.
This change ensures that any Rust subprocess gets access to the
UTC clock, if the parent had access to it. This is critical for
tests, which on Fuchsia, use panic=abort and spawn subprocesses
per test.
Update stdarch
This PR **changes the public signature** of the following functions in `core::arch::{x86, x86_64}`:
```patch
-pub unsafe fn _mm256_extract_epi8(a: __m256i, imm8: i32) -> i8
+pub unsafe fn _mm256_extract_epi8(a: __m256i, imm8: i32) -> i32
-pub unsafe fn _mm256_extract_epi16(a: __m256i, imm8: i32) -> i16
+pub unsafe fn _mm256_extract_epi16(a: __m256i, imm8: i32) -> i32
```
This change is desired so that these signatures
* are similar to those of the 128-bit versions `_mm_extract_epi8` and `_mm_extract_epi16`
* match the Intel definitions for the intrinsics
* [RFC 2325](https://github.com/rust-lang/rfcs/blob/master/text/2325-stable-simd.md) specifies that the exact vendor function signatures should be used
A [crater run](https://github.com/rust-lang/rust/pull/73166#issuecomment-667230319) revealed only a single breakage. The [vektor crate](https://github.com/AdamNiederer/vektor/blob/master/src/x86/avx2.rs#L2436-L2472) copied the incorrect signatures in `core` exactly to their own crate. The functions don't seem to be used by anyone anywhere.
Actual breakage is not expected, since due to the nature of the functions, users would generally write `_mm256_extract_epi8(...) as u8` or `_mm256_extract_epi16(...) as u16`.
See https://github.com/rust-lang/stdarch/pull/868/. Note that the changes from that stdarch PR have already partially landed in core after https://github.com/rust-lang/stdarch/pull/878/. This PR is now only about the remaining changes.
Implementation of peer credentials for Unix sockets
The code in `ucred.rs` is based on the work done in [PR 13](https://github.com/tokio-rs/tokio-uds/pull/13) in the tokio-uds repository on GitHub.
This commit is effectively a port to the stdlib, so credit to Martin Habovštiak (`@Kixunil)` and contributors for the meat of this work. 🥇
Happy to make changes as needed. 🙂
Split `core::slice` to smaller mods
Unfortunately the `#[lang = "slice"]` is too big (3003 lines), I cannot split it further.
Note for reviewer:
* I split to multiple commits for easier reviewing, but I could git squash them all to one if requested.
* Recommend pulling this change locally and using advanced git diff viewer or this command:
```
git show --reverse --color-moved=dimmed-zebra master..
```
---
I split core/slice/mod.rs to these modules:
* `ascii`: For operations on `[u8]`.
* `cmp`: For comparison operations on `[T]`, like PartialEq and SliceContains impl.
* `index`: For indexing operations like Index/IndexMut and SliceIndex.
* `iter`: For Iterator definitions and implementation on `[T]`.
- `macros`: For iterator! and forward_iterator! macros.
* `raw`: For free function to create `&[T]` or `&mut [T]` from pointer + length or a reference.
The heapsort wrapper in mod.rs is removed in favor of reexport from `sort::heapsort`.
Optimize behavior of vec.split_off(0) (take all)
Optimization improvement to `split_off()` so the performance meets the
intuitively expected behavior when `at == 0`, avoiding the current behavior
of copying the entire vector.
The change honors documented behavior that the original vector's
"previous capacity unchanged".
This improvement better supports the pattern for building and flushing a
buffer of elements, such as the following:
```rust
let mut vec = Vec::new();
loop {
vec.push(something);
if condition_is_met {
process(vec.split_off(0));
}
}
```
`Option` wrapping is the first alternative I thought of, but is much
less obvious and more verbose:
```rust
let mut capacity = 1;
let mut vec: Option<Vec<Stuff>> = None;
loop {
vec.get_or_insert_with(|| Vec::with_capacity(capacity)).push(something);
if condition_is_met {
capacity = vec.capacity();
process(vec.take().unwrap());
}
}
```
Directly using `mem::replace()` (instead of calling`split_off()`) could work,
but `mem::replace()` is a more advanced tool for Rust developers, and in
this case, I believe developers would assume the standard library should
be sufficient for the purpose described here.
The benefit of the approach to this change is it does not change the
existing API contract, but improves the peformance of `split_off(0)` for
`Vec`, `String` (which delegates `split_off()` to `Vec`), and any other
existing use cases.
This change adds tests to validate the behavior of `split_off()` with
regard to capacity, as originally documented, and confirm that behavior
still holds, when `at == 0`.
The change is an implementation detail, and does not require a
documentation change, but documenting the new behavior as part of its
API contract may benefit future users.
(Let me know if I should make that documentation update.)
Note, for future consideration:
I think it would be helpful to introduce an additional method to `Vec`
(if not also to `String`):
```
pub fn take_all(&mut self) -> Self {
self.split_off(0)
}
```
This would make it more clear how `Vec` supports the pattern, and make
it easier to find, since the behavior is similar to other `take()`
methods in the Rust standard library.
r? `@wesleywiser`
FYI: `@tmandry`
The code in `ucred.rs` is based on the work done in PR 13 in the
tokio-uds repository on GitHub. Link below for reference:
https://github.com/tokio-rs/tokio-uds/pull/13
Credit to Martin Habovštiak (GitHub username Kixunil) and contributors
for this work!
Optimization improvement to `split_off()` so the performance meets the
intuitively expected behavior when `at == 0`, avoiding the current
behavior of copying the entire vector.
The change honors documented behavior that the method leaves the
original vector's "previous capacity unchanged".
This improvement better supports the pattern for building and flushing a
buffer of elements, such as the following:
```rust
let mut vec = Vec::new();
loop {
vec.push(something);
if condition_is_met {
process(vec.split_off(0));
}
}
```
`Option` wrapping is the first alternative I thought of, but is much
less obvious and more verbose:
```rust
let mut capacity = 1;
let mut vec: Option<Vec<Stuff>> = None;
loop {
vec.get_or_insert_with(|| Vec::with_capacity(capacity)).push(something);
if condition_is_met {
capacity = vec.capacity();
process(vec.take().unwrap());
}
}
```
Directly applying `mem::replace()` could work, but `mem::` functions are
typically a last resort, when a developer is actively seeking better
performance than the standard library provides, for example.
The benefit of the approach to this change is it does not change the
existing API contract, but improves the peformance of `split_off(0)` for
`Vec`, `String` (which delegates `split_off()` to `Vec`), and any other
existing use cases.
This change adds tests to validate the behavior of `split_off()` with
regard to capacity, as originally documented, and confirm that behavior
still holds, when `at == 0`.
The change is an implementation detail, and does not require a
documentation change, but documenting the new behavior as part of its
API contract may benefit future users.
(Let me know if I should make that documentation update.)
Note, for future consideration:
I think it would be helpful to introduce an additional method to `Vec`
(if not also to `String`):
```
pub fn take_all(&mut self) -> Self {
self.split_off(0)
}
```
This would make it more clear how `Vec` supports the pattern, and make
it easier to find, since the behavior is similar to other `take()`
methods in the Rust standard library.
Remove internal and unstable MaybeUninit::UNINIT.
Looks like it is no longer necessary, as `uninit_array()` can be used instead in the few cases where it was needed.
(I wanted to just add `#[doc(hidden)]` to remove clutter from the documentation, but looks like it can just be removed entirely.)
