Update `catch_unwind` doc comments for `c_unwind`
Updates `catch_unwind` doc comments to indicate that catching a foreign exception _will no longer_ be UB. Instead, there are two possible behaviors, though it is not specified which one an implementation will choose.
Nominated for t-lang to confirm that they are okay with making such a promise based on t-opsem FCP, or whether they would like to be included in the FCP.
Related: https://github.com/rust-lang/rust/issues/74990, https://github.com/rust-lang/rust/issues/115285, https://github.com/rust-lang/reference/pull/1226
- Makes wording more clear and re-structures some
sections that can be overwhelming for some not
already in the know.
- Adds examples of how *not* to implement Ord,
inspired by various anti-patterns found in real
world code.
update `compiler-builtins` to 0.1.126
this requires the addition of a bootstrap variant of the new `naked_asm!` macro
r? `@tgross35`
extracted from https://github.com/rust-lang/rust/pull/128651
[`cfg_match`] Generalize inputs
cc #115585
Changes the input type from `item` to `tt`, which makes the macro have the same functionality of `cfg_if`.
Also adds a test to ensure that `stmt_expr_attributes` is not triggered.
Utf8Chunks: add link to Utf8Chunk
It is currently surprisingly non-trivial to go from the `utf8_chunks` method to the docs of the `valid`/`invalid` methods used in the example. This should help.
Since the stabilization in #127679 has reached stage0, 1.82-beta, we can
start using `&raw` freely, and even the soft-deprecated `ptr::addr_of!`
and `ptr::addr_of_mut!` can stop allowing the unstable feature.
I intentionally did not change any documentation or tests, but the rest
of those macro uses are all now using `&raw const` or `&raw mut` in the
standard library.
fix some cfg logic around optimize_for_size and 16-bit targets
Fixes https://github.com/rust-lang/rust/issues/130818.
Fixes https://github.com/rust-lang/rust/issues/129910.
There are still some warnings when building on a 16bit target:
```
warning: struct `AlignedStorage` is never constructed
--> /home/r/src/rust/rustc.2/library/core/src/slice/sort/stable/mod.rs:135:8
|
135 | struct AlignedStorage<T, const N: usize> {
| ^^^^^^^^^^^^^^
|
= note: `#[warn(dead_code)]` on by default
warning: associated items `new` and `as_uninit_slice_mut` are never used
--> /home/r/src/rust/rustc.2/library/core/src/slice/sort/stable/mod.rs:141:8
|
140 | impl<T, const N: usize> AlignedStorage<T, N> {
| -------------------------------------------- associated items in this implementation
141 | fn new() -> Self {
| ^^^
...
145 | fn as_uninit_slice_mut(&mut self) -> &mut [MaybeUninit<T>] {
| ^^^^^^^^^^^^^^^^^^^
warning: function `quicksort` is never used
--> /home/r/src/rust/rustc.2/library/core/src/slice/sort/unstable/quicksort.rs:19:15
|
19 | pub(crate) fn quicksort<'a, T, F>(
| ^^^^^^^^^
warning: `core` (lib) generated 3 warnings
```
However, the cfg stuff here is sufficiently messy that I didn't want to touch more of it. I think all `feature = "optimize_for_size"` should become `any(feature = "optimize_for_size", target_pointer_width = "16")` but I am not entirely certain. Warnings are fine, Miri will just ignore them.
Cc `@Voultapher`
Add `optimize_for_size` variants for stable and unstable sort as well as select_nth_unstable
- Stable sort uses a simple merge-sort that re-uses the existing - rather gnarly - merge function.
- Unstable sort jumps directly to the branchless heapsort fallback.
- select_nth_unstable jumps directly to the median_of_medians fallback, which is augmented with a custom tiny smallsort and partition impl.
Some code is duplicated but de-duplication would bring it's own problems. For example `swap_if_less` is critical for performance, if the sorting networks don't inline it perf drops drastically, however `#[inline(always)]` is also a poor fit, if the provided comparison function is huge, it gives the compiler an out to only instantiate `swap_if_less` once and call it. Another aspect that would suffer when making `swap_if_less` pub, is having to cfg out dozens of functions in in smallsort module.
Part of https://github.com/rust-lang/rust/issues/125612
r? `@Kobzol`
Mark `make_ascii_uppercase` and `make_ascii_lowercase` in `[u8]` and `str` as const.
Relevant tracking issue: #130698
This PR extends #130697 and #130713 to the similar methods in byte slices (`[u8]`) and string slices (`str`).
For the `str` methods, this simply requires adding the `const` specifier to the function signatures. The `[u8]` methods, however, require (at least a temporary) reimplementation due to the use of iterators and `for` loops.
Mark `u8::make_ascii_uppercase` and `u8::make_ascii_lowercase` as const.
Relevant tracking issue: #130698
This PR extends #130697 by also marking the `make_ascii_uppercase` and `make_ascii_lowercase` methods in `u8` as const.
The `const_char_make_ascii` feature gate is additionally renamed to `const_make_ascii`.
Support `char::encode_utf16` in const scenarios.
Relevant tracking issue: #130660
The method `char::encode_utf16` should be marked "const" to allow compile-time conversions.
This PR additionally rewrites the `encode_utf16_raw` function for better readability whilst also reducing the amount of unsafe code.
try-job: x86_64-msvc
Add str.as_str() for easy Deref to string slices
Working with `Box<str>` is cumbersome, because in places like `iter.filter()` it can end up being `&Box<str>` or even `&&Box<str>`, and such type doesn't always get auto-dereferenced as expected.
Dereferencing such box to `&str` requires ugly syntax like `&**boxed_str` or `&***boxed_str`, with the exact amount of `*`s.
`Box<str>` is [not easily comparable with other string types](https://github.com/rust-lang/rust/pull/129852) via `PartialEq`. `Box<str>` won't work for lookups in types like `HashSet<String>`, because `Borrow<String>` won't take types like `&Box<str>`. OTOH `set.contains(s.as_str())` works nicely regardless of levels of indirection.
`String` has a simple solution for this: the `as_str()` method, and `Box<str>` should too.
Mark `char::make_ascii_uppercase` and `char::make_ascii_lowercase` as const.
Relevant tracking issue: #130698
The `make_ascii_uppercase` and `make_ascii_lowercase` methods in `char` should be marked "const."
With the stabilisation of [`const_mut_refs`](https://github.com/rust-lang/rust/issues/57349/), this simply requires adding the `const` specifier to the function signatures.
Address diagnostics regression for `const_char_encode_utf8`.
Relevant tracking issue: #130512
This PR regains full diagnostics for non-const calls to `char::encode_utf8`.
[Clippy] Get rid of most `std` `match_def_path` usage, swap to diagnostic items.
Part of https://github.com/rust-lang/rust-clippy/issues/5393.
This was going to remove all `std` paths, but `SeekFrom` has issues being cleanly replaced with a diagnostic item as the paths are for variants, which currently cannot be diagnostic items.
This also, as a last step, categories the paths to help with future path removals.
Improve documentation for <integer>::from_str_radix
Two improvements to the documentation:
- Document `-` as a valid character for signed integer destinations
- Make the documentation even more clear that extra whitespace and non-digit characters is invalid. Many other languages, e.g. c++, are very permissive in string to integer routines and simply try to consume as much as they can, ignoring the rest. This is trying to make the transition for developers who are used to the conversion semantics in these languages a bit easier.
Pass `fmt::Arguments` by reference to `PanicInfo` and `PanicMessage`
Resolves#129330
For some reason after #115974 and #126732 optimizations applied to panic handler became worse and compiler stopped removing panic locations if they are not used in the panic message. This PR fixes that and maybe we can merge it into beta before rust 1.81 is released.
Note: optimization only works with `lto = "fat"`.
r? libs-api
Take more advantage of the `isize::MAX` limit in `Layout`
Things like `padding_needed_for` are current implemented being super careful to handle things like `Layout::size` potentially being `usize::MAX`.
But now that #95295 has happened, that's no longer a concern. It's possible to add two `Layout::size`s together without risking overflow now.
So take advantage of that to remove a bunch of checked math that's not actually needed. For example, the round-up-and-add-next-size in `extend` doesn't need any overflow checks at all, just the final check for compatibility with the alignment.
(And while I was doing that I made it all unstably const, because there's nothing in `Layout` that's fundamentally runtime-only.)
Things like `padding_needed_for` are current implemented being super careful to handle things like `Layout::size` potentially being `usize::MAX`.
But now that 95295 has happened, that's no longer a concern. It's possible to add two `Layout::size`s together without risking overflow now.
So take advantage of that to remove a bunch of checked math that's not actually needed. For example, the round-up-and-add-next-size in `extend` doesn't need any overflow checks at all, just the final check for compatibility with the alignment.
(And while I was doing that I made it all unstably const, because there's nothing in `Layout` that's fundamentally runtime-only.)
There is a Self: PartialOrd bound in Ord::clamp, but it is already
required by the trait itself. Likely a left-over from the const trait
deletion in 76dbe29104.
Reported-by: @noeensarguet
In the implementation of `force_mut`, I chose performance over safety.
For `LazyLock` this isn't really a choice; the code has to be unsafe.
But for `LazyCell`, we can have a full-safe implementation, but it will
be a bit less performant, so I went with the unsafe approach.
Document futility of printing temporary pointers
In the user forum I've seen a few people trying to understand how borrowing and moves are implemented by peppering their code with printing of `{:p}` of references to variables and expressions. This is a bad idea. It gives misleading and confusing results, because of autoderef magic, printing pointers of temporaries on the stack, and/or causes LLVM to optimize code differently when values had their address exposed.
simplify float::classify logic
I played around with the float-classify test in the hope of triggering x87 bugs by strategically adding `black_box`, and still the exact expression `@beetrees` suggested [here](https://github.com/rust-lang/rust/pull/129835#issuecomment-2325661597) remains the only case I found where we get the wrong result on x87. Curiously, this bug only occurs when MIR optimizations are enabled -- probably the extra inlining that does is required for LLVM to hit the right "bad" case in the backend. But even for that case, it makes no difference whether `classify` is implemented in the simple bit-pattern-based version or the more complicated version we had before.
Without even a single testcase that can distinguish our `classify` from the naive version, I suggest we switch to the naive version.
Add `core::panic::abort_unwind`
`abort_unwind` is like `catch_unwind` except that it aborts the process if it unwinds, using the `#[rustc_nounwind]` mechanism also used by `extern "C" fn` to abort unwinding. The docs attempt to make it clear when to (rarely) and when not to (usually) use the function.
Although usage of the function is discouraged, having it available will help to normalize the experience when abort_unwind shims are hit, as opposed to the current ecosystem where there exist multiple common patterns for converting unwinding into a process abort.
For further information and justification, see the linked ACP.
- Tracking issue: https://github.com/rust-lang/rust/issues/130338
- ACP: https://github.com/rust-lang/libs-team/issues/441
move Option::unwrap_unchecked into const_option feature gate
That's where `unwrap` and `expect` are so IMO it makes more sense to group them together.
Part of #91930, #67441
Stabilize `&mut` (and `*mut`) as well as `&Cell` (and `*const Cell`) in const
This stabilizes `const_mut_refs` and `const_refs_to_cell`. That allows a bunch of new things in const contexts:
- Mentioning `&mut` types
- Creating `&mut` and `*mut` values
- Creating `&T` and `*const T` values where `T` contains interior mutability
- Dereferencing `&mut` and `*mut` values (both for reads and writes)
The same rules as at runtime apply: mutating immutable data is UB. This includes mutation through pointers derived from shared references; the following is diagnosed with a hard error:
```rust
#[allow(invalid_reference_casting)]
const _: () = {
let mut val = 15;
let ptr = &val as *const i32 as *mut i32;
unsafe { *ptr = 16; }
};
```
The main limitation that is enforced is that the final value of a const (or non-`mut` static) may not contain `&mut` values nor interior mutable `&` values. This is necessary because the memory those references point to becomes *read-only* when the constant is done computing, so (interior) mutable references to such memory would be pretty dangerous. We take a multi-layered approach here to ensuring no mutable references escape the initializer expression:
- A static analysis rejects (interior) mutable references when the referee looks like it may outlive the current MIR body.
- To be extra sure, this static check is complemented by a "safety net" of dynamic checks. ("Dynamic" in the sense of "running during/after const-evaluation, e.g. at runtime of this code" -- in contrast to "static" which works entirely by looking at the MIR without evaluating it.)
- After the final value is computed, we do a type-driven traversal of the entire value, and if we find any `&mut` or interior-mutable `&` we error out.
- However, the type-driven traversal cannot traverse `union` or raw pointers, so there is a second dynamic check where if the final value of the const contains any pointer that was not derived from a shared reference, we complain. This is currently a future-compat lint, but will become an ICE in #128543. On the off-chance that it's actually possible to trigger this lint on stable, I'd prefer if we could make it an ICE before stabilizing const_mut_refs, but it's not a hard blocker. This part of the "safety net" is only active for mutable references since with shared references, it has false positives.
Altogether this should prevent people from leaking (interior) mutable references out of the const initializer.
While updating the tests I learned that surprisingly, this code gets rejected:
```rust
const _: Vec<i32> = {
let mut x = Vec::<i32>::new(); //~ ERROR destructor of `Vec<i32>` cannot be evaluated at compile-time
let r = &mut x;
let y = x;
y
};
```
The analysis that rejects destructors in `const` is very conservative when it sees an `&mut` being created to `x`, and then considers `x` to be always live. See [here](https://github.com/rust-lang/rust/issues/65394#issuecomment-541499219) for a longer explanation. `const_precise_live_drops` will solve this, so I consider this problem to be tracked by https://github.com/rust-lang/rust/issues/73255.
Cc `@rust-lang/wg-const-eval` `@rust-lang/lang`
Cc https://github.com/rust-lang/rust/issues/57349
Cc https://github.com/rust-lang/rust/issues/80384
simd_shuffle: require index argument to be a vector
Remove some codegen hacks by forcing the SIMD shuffle `index` argument to be a vector, which means (thanks to https://github.com/rust-lang/rust/pull/128537) that it will automatically be passed as an immediate in LLVM. The only special-casing we still have is for the extra sanity-checks we add that ensure that the indices are all in-bounds. (And the GCC backend needs to do a bunch of work since the Rust intrinsic is modeled after what LLVM expects, which seems to be quite different from what GCC expects.)
Fixes https://github.com/rust-lang/rust/issues/128738, see that issue for more context.
fix doc comments for Peekable::next_if(_eq)
Fix references to a nonexistent `consume` function in the doc comments for `Peekable::next_if` and `Peekable::next_if_eq`.
some const cleanup: remove unnecessary attributes, add const-hack indications
I learned that we use `FIXME(const-hack)` on top of the "const-hack" label. That seems much better since it marks the right place in the code and moves around with the code. So I went through the PRs with that label and added appropriate FIXMEs in the code. IMO this means we can then remove the label -- Cc ``@rust-lang/wg-const-eval.``
I also noticed some const stability attributes that don't do anything useful, and removed them.
r? ``@fee1-dead``
Rollup of 11 pull requests
Successful merges:
- #128316 (Stabilize most of `io_error_more`)
- #129473 (use `download-ci-llvm=true` in the default compiler config)
- #129529 (Add test to build crates used by r-a on stable)
- #129981 (Remove `serialized_bitcode` from `LtoModuleCodegen`.)
- #130094 (Inform the solver if evaluation is concurrent)
- #130132 ([illumos] enable SIGSEGV handler to detect stack overflows)
- #130146 (bootstrap `naked_asm!` for `compiler-builtins`)
- #130149 (Helper function for formatting with `LifetimeSuggestionPosition`)
- #130152 (adapt a test for llvm 20)
- #130162 (bump download-ci-llvm-stamp)
- #130164 (move some const fn out of the const_ptr_as_ref feature)
r? `@ghost`
`@rustbot` modify labels: rollup
move some const fn out of the const_ptr_as_ref feature
When a `const fn` is still `#[unstable]`, it should generally use the same feature to track its regular stability and const-stability. Then when that feature moves towards stabilization we can decide whether the const-ness can be stabilized as well, or whether it should be moved into a new feature.
Also, functions like `ptr::as_ref` (which returns an `Option<&mut T>`) require `is_null`, which is tricky and blocked on some design concerns (see #74939). So move those to the is_null feature gate, as they should be stabilized together with `ptr.is_null()`.
Affects #91822, #122034, #75402, https://github.com/rust-lang/rust/issues/74939
bootstrap `naked_asm!` for `compiler-builtins`
tracking issue: https://github.com/rust-lang/rust/issues/90957
parent PR: https://github.com/rust-lang/rust/pull/128651
in this PR, `naked_asm!` is added as an alias for `asm!` with one difference: `options(noreturn)` is always enabled by `naked_asm!`. That makes it future-compatible for when `naked_asm!` starts disallowing `options(noreturn)` later.
The `naked_asm!` macro must be introduced first so that we can upgrade `compiler-builtins` to use it, and can then change the implementation of `naked_asm!` in https://github.com/rust-lang/rust/pull/128651
I've added some usages for `naked_asm!` in the tests, so we can be confident that it works, but I've left upgrading the whole test suite to the parent PR.
r? ``@Amanieu``
interpret: make typed copies lossy wrt provenance and padding
A "typed copy" in Rust can be a lossy process: when copying at type `usize` (or any other non-pointer type), if the original memory had any provenance, that provenance is lost. When copying at pointer type, if the original memory had partial provenance (i.e., not the same provenance for all bytes), that provenance is lost. When copying any type with padding, the contents of padding are lost.
This PR equips our validity-checking pass with the ability to reset provenance and padding according to those rules. Can be reviewed commit-by-commit. The first three commits are just preparation without any functional change.
Fixes https://github.com/rust-lang/miri/issues/845
Fixes https://github.com/rust-lang/miri/issues/2182
in this commit, `naked_asm!` is an alias for `asm!` with one difference: `options(noreturn)` is always enabled by `naked_asm!`. That makes it future-compatible for when `naked_asm!` starts disallowing `options(noreturn)` later.
const: make ptr.is_null() stop execution on ambiguity
This seems better than saying `false` -- saying `false` is in fact actively unsound if `NonNull` then uses this to permit putting this pointer inside of it, but at runtime it turns out to be null.
Part of https://github.com/rust-lang/rust/issues/74939
Cc ```@rust-lang/wg-const-eval```
remove 'const' from 'Option::iter'
This is kind of pointless to be a `const fn` since you can't do anything with the iterator. It is also the only `const fn iter*` in the entire standard library. It probably got constified when `~const` traits got added everywhere, and then was forgotten to be de-constified when that was undone.
The rest of the const_option feature seems like it can reasonably be stabilized, but this one IMO should not be stabilized, and it's not worth creating a new tracking issue.
Cc https://github.com/rust-lang/rust/issues/67441
Rollup of 10 pull requests
Successful merges:
- #126452 (Implement raw lifetimes and labels (`'r#ident`))
- #129555 (stabilize const_float_bits_conv)
- #129594 (explain the options bootstrap passes to curl)
- #129677 (Don't build by-move body when async closure is tainted)
- #129847 (Do not call query to compute coroutine layout for synthetic body of async closure)
- #129869 (add a few more crashtests)
- #130009 (rustdoc-search: allow trailing `Foo ->` arg search)
- #130046 (str: make as_mut_ptr and as_bytes_mut unstably const)
- #130047 (Win: Add dbghelp to the list of import libraries)
- #130059 (Remove the unused `llvm-skip-rebuild` option from x.py)
r? `@ghost`
`@rustbot` modify labels: rollup
str: make as_mut_ptr and as_bytes_mut unstably const
`@rust-lang/libs-api` the corresponding non-mutable methods are already const fn, so this seems pretty trivial. I hope this is small enough that it does not need an ACP? :)
I would like to get these stabilized ASAP because I want to avoid people doing `s.as_ptr().cast_mut()`, which is UB if they ever write to it, but is already const-stable.
TODO: create a tracking issue.
Elaborate on deriving vs implementing `Copy`
I was reading this documentation and this wasn't immediately clear to me.
In my mind, it seemed obvious that a type can only claim to be `Copy` if the bits it is storing can be `Copy`, and in the case of a generic struct that can only be the case if `T: Copy`. So the bound added by the derive seemed necessary at all times, and I thought what the documentation was trying to say is that the custom implementation allows you to add _additional bounds_.
Of course what it was actually trying to point out is that just because you have a generic parameter `T`, it doesn't necessarily mean you are storing the bits of `T`. And if you aren't, it may be the case that your own bits can be copied regardless of whether the bits of `T` can be safely copied.
Thought it may be worth elaborating to make that a bit more clear. Haven't tested/didn't try to figure out how to render this locally. Mainly not sure if the `PhantomData` back link is going to just work or need some extra stuff, but I figured someone else probably could just tell.
Stabilize `waker_getters`
Tracking issue: #96992
FCP completed on the tracking issue a while ago. It's not clear whether the libs-api team wanted the `RawWaker` methods moved to `Waker` or went back to the current API after further discussion. `@Amanieu` [wrote "This is just waiting for someone to submit a stabilization PR."](https://github.com/rust-lang/rust/issues/96992#issuecomment-2213685218) so I'm doing just that in hopes of nudging this along.
Edit: Moved the `data` and `vtable` methods from `RawWaker` to `Waker` and added `Waker::new` per https://github.com/rust-lang/rust/issues/96992#issuecomment-1941998046
```rs
impl Waker {
pub const unsafe fn new(data: *const (), vtable: &'static RawWakerVTable) -> Self;
pub fn data(&self) -> *const ();
pub fn vtable(&self) -> &'static RawWakerVTable;
}
```
Closes#96992
Add target support for RTEMS Arm
# `armv7-rtems-eabihf`
This PR adds a new target for the RTEMS RTOS. To get things started it focuses on Xilinx/AMD Zynq-based targets, but in theory it should also support other armv7-based board support packages in the future.
Given that RTEMS has support for many POSIX functions it is mostly enabling corresponding unix features for the new target.
I also previously started a PR in libc (https://github.com/rust-lang/libc/pull/3561) to add the needed OS specific C-bindings and was told that a PR in this repo is needed first. I will update the PR to the newest version after approval here.
I will probably also need to change one line in the backtrace repo.
Current status is that I could compile rustc for the new target locally (with the updated libc and backtrace) and could compile binaries, link, and execute a simple "Hello World" RTEMS application for the target hardware.
> A proposed target or target-specific patch that substantially changes code shared with other targets (not just target-specific code) must be reviewed and approved by the appropriate team for that shared code before acceptance.
There should be no breaking changes for existing targets. Main changes are adding corresponding `cfg` switches for the RTEMS OS and adding the C binding in libc.
# Tier 3 target policy
> - A tier 3 target must have a designated developer or developers (the "target maintainers") on record to be CCed when issues arise regarding the target. (The mechanism to track and CC such developers may evolve over time.)
I will do the maintenance (for now) further members of the RTEMS community will most likely join once the first steps have been done.
> - Targets must use naming consistent with any existing targets; for instance, a target for the same CPU or OS as an existing Rust target should use the same name for that CPU or OS. Targets should normally use the same names and naming conventions as used elsewhere in the broader ecosystem beyond Rust (such as in other toolchains), unless they have a very good reason to diverge. Changing the name of a target can be highly disruptive, especially once the target reaches a higher tier, so getting the name right is important even for a tier 3 target.
> - Target names should not introduce undue confusion or ambiguity unless absolutely necessary to maintain ecosystem compatibility. For example, if the name of the target makes people extremely likely to form incorrect beliefs about what it targets, the name should be changed or augmented to disambiguate it.
> - If possible, use only letters, numbers, dashes and underscores for the name. Periods (`.`) are known to cause issues in Cargo.
The proposed triple is `armv7-rtems-eabihf`
> - Tier 3 targets may have unusual requirements to build or use, but must not create legal issues or impose onerous legal terms for the Rust project or for Rust developers or users.
> - The target must not introduce license incompatibilities.
> - Anything added to the Rust repository must be under the standard Rust license (`MIT OR Apache-2.0`).
> - The target must not cause the Rust tools or libraries built for any other host (even when supporting cross-compilation to the target) to depend on any new dependency less permissive than the Rust licensing policy. This applies whether the dependency is a Rust crate that would require adding new license exceptions (as specified by the `tidy` tool in the rust-lang/rust repository), or whether the dependency is a native library or binary. In other words, the introduction of the target must not cause a user installing or running a version of Rust or the Rust tools to be subject to any new license requirements.
> - Compiling, linking, and emitting functional binaries, libraries, or other code for the target (whether hosted on the target itself or cross-compiling from another target) must not depend on proprietary (non-FOSS) libraries. Host tools built for the target itself may depend on the ordinary runtime libraries supplied by the platform and commonly used by other applications built for the target, but those libraries must not be required for code generation for the target; cross-compilation to the target must not require such libraries at all. For instance, `rustc` built for the target may depend on a common proprietary C runtime library or console output library, but must not depend on a proprietary code generation library or code optimization library. Rust's license permits such combinations, but the Rust project has no interest in maintaining such combinations within the scope of Rust itself, even at tier 3.
> - "onerous" here is an intentionally subjective term. At a minimum, "onerous" legal/licensing terms include but are _not_ limited to: non-disclosure requirements, non-compete requirements, contributor license agreements (CLAs) or equivalent, "non-commercial"/"research-only"/etc terms, requirements conditional on the employer or employment of any particular Rust developers, revocable terms, any requirements that create liability for the Rust project or its developers or users, or any requirements that adversely affect the livelihood or prospects of the Rust project or its developers or users.
The tools consists of the cross-compiler toolchain (gcc-based). The RTEMS kernel (BSD license) and parts of the driver stack of FreeBSD (BSD license). All tools are FOSS and publicly available here: https://gitlab.rtems.org/rtems
There are also no new features or dependencies introduced to the Rust code.
> - Neither this policy nor any decisions made regarding targets shall create any binding agreement or estoppel by any party. If any member of an approving Rust team serves as one of the maintainers of a target, or has any legal or employment requirement (explicit or implicit) that might affect their decisions regarding a target, they must recuse themselves from any approval decisions regarding the target's tier status, though they may otherwise participate in discussions.
N/A to me. I am not a reviewer nor Rust team member.
> - Tier 3 targets should attempt to implement as much of the standard libraries as possible and appropriate (`core` for most targets, `alloc` for targets that can support dynamic memory allocation, `std` for targets with an operating system or equivalent layer of system-provided functionality), but may leave some code unimplemented (either unavailable or stubbed out as appropriate), whether because the target makes it impossible to implement or challenging to implement. The authors of pull requests are not obligated to avoid calling any portions of the standard library on the basis of a tier 3 target not implementing those portions.
`core` and `std` compile. Some advanced features of the `std` lib might not work yet. However, the goal of this tier 3 target it to make it easier for other people to build and run test applications to better identify the unsupported features and work towards enabling them.
> - The target must provide documentation for the Rust community explaining how to build for the target, using cross-compilation if possible. If the target supports running binaries, or running tests (even if they do not pass), the documentation must explain how to run such binaries or tests for the target, using emulation if possible or dedicated hardware if necessary.
Building is described in platform support doc. Running simple unit tests works. Running the test suite of the stdlib is currently not that easy. Trying to work towards that after the this target has been added to the nightly.
> - Tier 3 targets must not impose burden on the authors of pull requests, or other developers in the community, to maintain the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on a tier 3 target. Do not send automated messages or notifications (via any medium, including via ````@`)``` to a PR author or others involved with a PR regarding a tier 3 target, unless they have opted into such messages.
Understood.
> - Backlinks such as those generated by the issue/PR tracker when linking to an issue or PR are not considered a violation of this policy, within reason. However, such messages (even on a separate repository) must not generate notifications to anyone involved with a PR who has not requested such notifications.
Ok
> - Patches adding or updating tier 3 targets must not break any existing tier 2 or tier 1 target, and must not knowingly break another tier 3 target without approval of either the compiler team or the maintainers of the other tier 3 target.
> - In particular, this may come up when working on closely related targets, such as variations of the same architecture with different features. Avoid introducing unconditional uses of features that another variation of the target may not have; use conditional compilation or runtime detection, as appropriate, to let each target run code supported by that target.
I think, I didn't add any breaking changes for any existing targets (see the comment regarding features above).
> - Tier 3 targets must be able to produce assembly using at least one of rustc's supported backends from any host target.
Can produce assembly code via the llvm backend (tested on Linux).
>
> If a tier 3 target stops meeting these requirements, or the target maintainers no longer have interest or time, or the target shows no signs of activity and has not built for some time, or removing the target would improve the quality of the Rust codebase, we may post a PR to remove it; any such PR will be CCed to the target maintainers (and potentially other people who have previously worked on the target), to check potential interest in improving the situation.GIAt this tier, the Rust project provides no official support for a target, so we place minimal requirements on the introduction of targets.
Understood.
r? compiler-team
This regresses binary-size slightly for normal builds, but the important
release_lto_thin_opt_level_s config sees a small improvement in
binary-size and a larger types such as string and 1k see 2-3% run-time
improvements with this change.
While using it results in slightly slammer binaries, it's not deemed
worth it to add yet another sort algorithm to the standard library.
select_nth_unstable has bigger binary-size problems.
Clarify language around ptrs in slice::raw
More specifically we explicitly mention that the pointer should be non-null as a top level requirement. Nullptrs are always valid for zero sized operations, so just validity (and alignment) does not guarantee non-nullness as implied in the existing docs.
We also explicitly call out ZSTs as an additional example where perhaps unintuitively alignment and non-nullness still have to hold.
Finally we change `data` in the range functions to `start`, which seems like a typo to me.
Touches docs for #89792
r? RalfJung
compiler_fence documentation: emphasize synchronization, not reordering
Our `fence` docs have at some point been update to explain that they are about synchronization, not about "preventing reordering". This updates the `compiler_fence` docs n the same vein, mostly by referring to the `fence` docs.
The old docs make it sound like I can put a compiler_fence in the middle of a bunch of non-atomic operations and that would achieve any kind of guarantee. It does not, atomic operations are still required to do synchronization.
I also slightly tweaked the `fence` docs, to put the synchronization first and the "prevent reordering" second.
Cc `@rust-lang/opsem` `@chorman0773` `@m-ou-se`
Fixes https://github.com/rust-lang/rust/issues/129189
Fixes https://github.com/rust-lang/rust/issues/54962
Rollup of 9 pull requests
Successful merges:
- #127474 (doc: Make block of inline Deref methods foldable)
- #129678 (Deny imports of `rustc_type_ir::inherent` outside of type ir + new trait solver)
- #129738 (`rustc_mir_transform` cleanups)
- #129793 (add extra linebreaks so rustdoc can identify the first sentence)
- #129804 (Fixed some typos in the standard library documentation/comments)
- #129837 (Actually parse stdout json, instead of using hacky contains logic.)
- #129842 (Fix LLVM ABI NAME for riscv64imac-unknown-nuttx-elf)
- #129843 (Mark myself as on vacation for triagebot)
- #129858 (Replace walk with visit so we dont skip outermost expr kind in def collector)
Failed merges:
- #129777 (Add `unreachable_pub`, round 4)
- #129868 (Remove kobzol vacation status)
r? `@ghost`
`@rustbot` modify labels: rollup
add extra linebreaks so rustdoc can identify the first sentence
there should probably be a lint against this in rustdoc, it causes too many lines to be shown in the short documentation overviews
expecially noticable for the slice primative type: https://doc.rust-lang.org/std/index.html
Apply size optimizations to panic machinery and some cold functions
* std dependencies gimli and addr2line are now built with opt-level=s
* various panic-related methods and `#[cold]` methods are now marked `#[optimize(size)]`
Panics should be cold enough that it doesn't make sense to optimize them for speed. The only tradeoff here is if someone does a lot of backtrace captures (without panics) and printing then the opt-level change might impact their perf.
Seems to be the first use of the optimize attribute. Tracking issue #54882
there should probably be a lint against this in rustdoc, it causes
too many lines to be shown in the short documentation overviews
expecially noticable for the slice primative type:
https://doc.rust-lang.org/std/index.html
refactor: standardize duplicate processes in parser
## Summary
This PR refactors the `read_number` function to standardize duplicate code, improve readability, and enhance efficiency.
## Changes
- Merged the logic for both `max_digits` cases into a single `read_atomically` closure
- Simplified control flow and reduced code duplication
core: use `compare_bytes` for more slice element types
`bool`, `NonZero<u8>`, `Option<NonZero<u8>>` and `ascii::Char` can be compared the same way as `u8`.
Rollup of 11 pull requests
Successful merges:
- #128523 (Add release notes for 1.81.0)
- #129605 (Add missing `needs-llvm-components` directives for run-make tests that need target-specific codegen)
- #129650 (Clean up `library/profiler_builtins/build.rs`)
- #129651 (skip stage 0 target check if `BOOTSTRAP_SKIP_TARGET_SANITY` is set)
- #129684 (Enable Miri to pass pointers through FFI)
- #129762 (Update the `wasm-component-ld` binary dependency)
- #129782 (couple more crash tests)
- #129816 (tidy: say which feature gate has a stability issue mismatch)
- #129818 (make the const-unstable-in-stable error more clear)
- #129824 (Fix code examples buttons not appearing on click on mobile)
- #129826 (library: Fix typo in `core::mem`)
r? `@ghost`
`@rustbot` modify labels: rollup
Two improvements to the documentation:
- Document `-` as a valid character for signed integer destinations
- Make the documentation even more clear that extra whitespace and non-digit characters is invalid. Many other
languages, e.g. c++, are very permissive in string to integer routines and simply try to consume as much as they can,
ignoring the rest. This is trying to make the transition for developers who are used to the conversion semantics in
these languages a bit easier.
Re-enable android tests/benches in alloc/core
This is basically a revert of https://github.com/rust-lang/rust/pull/73729. These tests better work on android now; it's been 4 years and we don't use dlmalloc on that target anymore.
And I've validated that they should pass now with a try-build :)
* Use a lookup table for 8-bit integers and the Karatsuba square root
algorithm for larger integers.
* Include optimization hints that give the compiler the exact numeric
range of results.
* Choose test inputs more thoroughly and systematically.
* Check that `isqrt` and `checked_isqrt` have equivalent results for
signed types, either equivalent numerically or equivalent as a panic
and a `None`.
* Check that `isqrt` has numerically-equivalent results for unsigned
types and their `NonZero` counterparts.
* Reuse `ilog10` benchmarks, plus benchmarks that use a uniform
distribution.
Rollup of 11 pull requests
Successful merges:
- #129421 (add repr to the allowlist for naked functions)
- #129480 (docs: correct panic conditions for rem_euclid and similar functions)
- #129551 (ub_checks intrinsics: fall back to cfg(ub_checks))
- #129608 (const-eval: do not make UbChecks behavior depend on current crate's flags)
- #129613 (interpret: do not make const-eval query result depend on tcx.sess)
- #129641 (rustdoc: fix missing resource suffix on `crates.js`)
- #129657 (Rename `BikeshedIntrinsicFrom` to `TransmuteFrom`)
- #129666 (interpret: add missing alignment check in raw_eq)
- #129667 (Rustc driver cleanup)
- #129668 (Fix Pin::set bounds regression)
- #129686 (coverage: Rename `CodeRegion` to `SourceRegion`)
r? `@ghost`
`@rustbot` modify labels: rollup
Rename `BikeshedIntrinsicFrom` to `TransmuteFrom`
As our implementation of MCP411 nears completion and we begin to solicit testing, it's no longer reasonable to expect testers to type or remember `BikeshedIntrinsicFrom`. The name degrades the ease-of-reading of documentation, and the overall experience of using compiler safe transmute.
Tentatively, we'll instead adopt `TransmuteFrom`.
This name seems to be the one most likely to be stabilized, after discussion on Zulip [1]. We may want to revisit the ordering of `Src` and `Dst` before stabilization, at which point we'd likely consider `TransmuteInto` or `Transmute`.
[1] https://rust-lang.zulipchat.com/#narrow/stream/216762-project-safe-transmute/topic/What.20should.20.60BikeshedIntrinsicFrom.60.20be.20named.3F
Tracking Issue: https://github.com/rust-lang/rust/issues/99571
r? `@compiler-errors`
ub_checks intrinsics: fall back to cfg(ub_checks)
Not sure why the fallback body uses `debug_assertions`, probably a leftover from when `cfg!(ub_checks)` did not exist yet?
r? `@saethlin`
Tweak some attributes to improve panic_immediate_abort
This is similar to https://github.com/rust-lang/rust/pull/117332; I did the same approach as before where I build a really big project with `-Zbuild-std -Zbuild-std-features=panic_immediate_abort` and grep its symbols for things that look panic-related.
Fix typos in floating-point primitive type docs
Fixes a few typos. Also reflows the text of a couple of paragraphs in the source code to the standard line width to make the source easier to read (will have no effect on the rendered documentation).
As our implementation of MCP411 nears completion and we begin to
solicit testing, it's no longer reasonable to expect testers to
type or remember `BikeshedIntrinsicFrom`. The name degrades the
ease-of-reading of documentation, and the overall experience of
using compiler safe transmute.
Tentatively, we'll instead adopt `TransmuteFrom`.
This name seems to be the one most likely to be stabilized, after
discussion on Zulip [1]. We may want to revisit the ordering of
`Src` and `Dst` before stabilization, at which point we'd likely
consider `TransmuteInto` or `Transmute`.
[1] https://rust-lang.zulipchat.com/#narrow/stream/216762-project-safe-transmute/topic/What.20should.20.60BikeshedIntrinsicFrom.60.20be.20named.3F
simd_shuffle intrinsic: allow argument to be passed as vector
See https://github.com/rust-lang/rust/issues/128738 for context.
I'd like to get rid of [this hack](6c0b89dfac/compiler/rustc_codegen_ssa/src/mir/block.rs (L922-L935)). https://github.com/rust-lang/rust/pull/128537 almost lets us do that since constant SIMD vectors will then be passed as immediate arguments. However, simd_shuffle for some reason actually takes an *array* as argument, not a vector, so the hack is still required to ensure that the array becomes an immediate (which then later stages of codegen convert into a vector, as that's what LLVM needs).
This PR prepares simd_shuffle to also support a vector as the `idx` argument. Once this lands, stdarch can hopefully be updated to pass `idx` as a vector, and then support for arrays can be removed, which finally lets us get rid of that hack.
Document & implement the transmutation modeled by `BikeshedIntrinsicFrom`
Documents that `BikeshedIntrinsicFrom` models transmute-via-union, which is slightly more expressive than the transmute-via-cast implemented by `transmute_copy`. Additionally, we provide an implementation of transmute-via-union as a method on the `BikeshedIntrinsicFrom` trait with additional documentation on the boundary between trait invariants and caller obligations.
Whether or not transmute-via-union is the right kind of transmute to model remains up for discussion [1]. Regardless, it seems wise to document the present behavior.
[1] https://rust-lang.zulipchat.com/#narrow/stream/216762-project-safe-transmute/topic/What.20'kind'.20of.20transmute.20to.20model.3F/near/426331967
Tracking Issue: https://github.com/rust-lang/rust/issues/99571
r? `@compiler-errors`
cc `@scottmcm,` `@Lokathor`
Remove cfg(test) from library/core
The diff here is very small with the ignore whitespace option.
`core` doesn't/can't have unit tests. All of its tests are just modules under `tests/`, so it has no use for `cfg(test)`, because the entire contents of `library/core/src` are only ever compiled with that cfg off, and the entire contents of `library/core/tests` are only ever compiled with that cfg on.
You can tell this is what's happening because we had `#[cfg(test)]` on a module declaration that has no source file.
I also deleted the extra `mod tests {` layer of nesting; there's no need to mention again in the module path that this is a module of tests. This exposes a name collision between the `u128` module of tests and `core::u128`. Fixed that by using `<u128>::MAX` like is done in the `check!` macro, which is what avoids this name ambiguity for the other types.
link to Future::poll from the Poll docs
The most important thing about Poll is that Future::poll returns it, but previously the docs didn't emphasize this.
Add implementations for `unbounded_shl`/`unbounded_shr`
Tracking Issue: https://github.com/rust-lang/rust/issues/129375
This implements `unbounded_shl` and `unbounded_shr` under the feature gate `unbounded_shifts`
Rollup of 9 pull requests
Successful merges:
- #129288 (Use subtyping for `UnsafeFnPointer` coercion, too)
- #129405 (Fixing span manipulation and indentation of the suggestion introduced by #126187)
- #129518 (gitignore: ignore ICE reports regardless of directory)
- #129519 (Remove redundant flags from `lower_ty_common` that can be inferred from the HIR)
- #129525 (rustdoc: clean up tuple <-> primitive conversion docs)
- #129526 (Use `FxHasher` on new solver unconditionally)
- #129544 (Removes dead code from the compiler)
- #129553 (add back test for stable-const-can-only-call-stable-const)
- #129590 (Avoid taking reference of &TyKind)
r? `@ghost`
`@rustbot` modify labels: rollup
rustdoc: clean up tuple <-> primitive conversion docs
This adds a minor missing feature to `fake_variadic`, so that it can render `impl From<(T,)> for [T; 1]` correctly.
- Stable sort uses a simple merge-sort that re-uses the existing - rather gnarly - merge function.
- Unstable sort jumps directly to the branchless heapsort fallback.
- select_nth_unstable jumps directly to the median_of_medians fallback, which is augmented with a
custom tiny smallsort and partition impl.
Some code is duplicated but de-duplication would bring it's own problems. For example `swap_if_less`
is critical for performance, if the sorting networks don't inline it perf drops drastically,
however `#[inline(always)]` is also a poor fit, if the provided comparison function is huge,
it gives the compiler an out to only instantiate `swap_if_less` once and call it. Another aspect
that would suffer when making `swap_if_less` pub, is having to cfg out dozens of functions in
in smallsort module.
Put Pin::as_deref_mut in impl Pin<Ptr> / rearrange Pin methods
Tracking issue: #86918
Based on the suggestion in https://github.com/rust-lang/rust/issues/86918#issuecomment-2189367582
> Some advantages:
>
> * Synergy with the existing `as_ref` and `as_mut` signatures (stable since Rust 1.33)
>
> * Lifetime elision reduces noise in the signature
>
> * Turbofish less verbose: `Pin::<&mut T>::as_deref_mut` vs `Pin::<&mut Pin<&mut T>>::as_deref_mut`
The comment seemed to imply that `Pin::as_ref` and `Pin::as_mut` already share an impl block, which they don't. So, I rearranged it so that they do, and we can see which looks better in the docs.
<details><summary><b>Docs screenshots</b></summary>
Current nightly:
`Pin::as_deref_mut` moved into the same block as `as_mut`:
`Pin::as_ref`, `as_mut`, and `as_deref_mut` all in the same block:
</details>
I think I like the last one the most; obviously I'm biased since I'm the one who rearranged it, but it doesn't make sense to me to have `as_ref` methods split up by an `into_inner` method.
r? dtolnay
Add a special case for `CStr`/`CString` in the `improper_ctypes` lint
Revives #120176. Just needed to bless a test and fix an argument, but seemed reasonable to me otherwise.
Instead of saying to "consider adding a `#[repr(C)]` or `#[repr(transparent)]` attribute to this struct", we now tell users to "Use `*const ffi::c_char` instead, and pass the value from `CStr::as_ptr()`" when the type involved is a `CStr` or a `CString`.
The suggestion is not made for `&mut CString` or `*mut CString`.
r? ``````@cjgillot`````` (since you were the reviewer of the original PR #120176, but feel free to reroll)
remove invalid `TyCompat` relation for effects
if the current impl uses `Maybe` (`impl const`), the parent impl must use `Maybe` (`impl const`) as well.
I'd like to rename `TyCompat` to `Sub` which is probably clearer. But it would conflict with my other PR.
r? ``@rust-lang/project-const-traits``
