Add general arm-linux.md platform doc.
Adds a new page that covers all 32-bit Arm Linux systems. This means that we can reduce the amount of information required in the target specific pages to just the Tier level, the maintainer, and any specific details for that target.
I have no changed those pages yet, though. Let's start with this.
Resolve: (Ref)Cell wrappers to deny mutation during spec resolution.
Introduces wrappers around `Cell` and `RefCell` that only allow mutation when we are not in speculative resolution. This is preparatory work for rust-lang/rust#145108.
It would allow us to make `ImportData` and `ModuleData` sync and send safe.
r? ``@petrochenkov``
remove incorrect fast path
Using `tcx.is_copy_modulo_regions` drops information from the current `typing_env`. Writing a regression test for this is really hard. We need to prove `Copy` of something that doesn't directly reference a coroutine or an opaque, but does so indirectly.
cc rust-lang/rust#146813.
Make `render_example_with_highlighting` return an `impl fmt::Display`
Removes some more usages of `write_str`. Shouldn't affect runtime, but makes the codebase a bit more consistent.
Each commit can be reviewed separately
Add doc for `NonZero*` const creation
I ran into trouble using `NonZero*` values because I didn’t see any clear way to create them at compile time. At first I ended up using `NonZero*::new_unchecked` a lot, until I realized that `Option::unwrap` and `Option::expect` are `const` and can be used in a `const` context. With that, you can create non-zero values at compile time safely, without touching `unsafe`. This wasn’t obvious to me and my peers who’ve been using Rust for a while, so I thought adding a note to the docs would make it easier for others to discover.
If this should be worded differently or placed in another location, we can do that. I just want to make this more obvious.
BTreeMap: Don't leak allocators when initializing nodes
Memory was allocated via `Box::leak` and thence intended to be tracked and deallocated manually, but the allocator was also leaked, not tracked, and never dropped. Now it is dropped immediately.
According to my reading of the `Allocator` trait, if a copy of the allocator remains live, then its allocations must remain live. Since the B-tree has a copy of the allocator that will only be dropped after the nodes, it's safe to not store the allocator in each node (which would be a much more intrusive change).
Fixes: rust-lang/rust#106203
avoid violating `slice::from_raw_parts` safety contract in `Vec::extract_if`
The implementation of the `Vec::extract_if` iterator violates the safety contract adverized by `slice::from_raw_parts` by always constructing a mutable slice for the entire length of the vector even though that span of memory can contain holes from items already drained. The safety contract of `slice::from_raw_parts` requires that all elements must be properly
initialized.
As an example we can look at the following code:
```rust
let mut v = vec![Box::new(0u64), Box::new(1u64)];
for item in v.extract_if(.., |x| **x == 0) {
drop(item);
}
```
In the second iteration a `&mut [Box<u64>]` slice of length 2 will be constructed. The first slot of the slice contains the bitpattern of an already deallocated box, which is invalid.
This fixes the issue by only creating references to valid items and using pointer manipulation for the rest. I have also taken the liberty to remove the big `unsafe` blocks in place of targetted ones with a SAFETY comment. The approach closely mirrors the implementation of `Vec::retain_mut`.
**Note to reviewers:** The diff is easier to follow with whitespace hidden.
rustdoc: hide `#[repr]` if it isn't part of the public ABI
> [!IMPORTANT]
> Temporarily stacked on top of PR https://github.com/rust-lang/rust/pull/146527; only the last commit is relevant!
Follow-up to rust-lang/rust#115439.
Unblocks rust-lang/rust#116743, CC ``@dtolnay.``
Fixesrust-lang/rust#66401.
Fixesrust-lang/rust#128364.
Fixesrust-lang/rust#137440.
Only display the representation `#[repr(REPR)]` (where `REPR` is not `Rust` or `transparent`) of a given type if none of its variants (incl. the synthetic variants of structs) are `#[doc(hidden)]` and all of its fields are public and not `#[doc(hidden)]` since it's likely not meant to be considered part of the public ABI otherwise.
`--document-{private,hidden}-items` works as expected in this context, too.
Moreover, we now also factor in the presence of `#[doc(hidden)]` when checking whether to show `repr(transparent)` or not.
Use `LLVMDisposeTargetMachine`
After bumping the minimum LLVM version to 20 (rust-lang/rust#145071), we no longer need to run any custom code when disposing of a TargetMachine, so we can just use the upstream LLVM-C function.
bootstrap.py: Respect build.jobs while building bootstrap tool
On resource-constrained systems, it is vital to respect the value of build.jobs, in order to avoid overwhelming the available memory.
Explicitly note `&[SocketAddr]` impl of `ToSocketAddrs`
Although the examples below this list do imply that there's an impl of `ToSocketAddrs` for `&[SocketAddr]`, it's not actually noted in the list of default implementations.
Small string formatting cleanup
This PR is mostly useless. I was going through this file, saw that and corrected it. That's pretty much it. Feel free to close it if it's a bother.
llvm: update remarks support on LLVM 22
LLVM change dfbd76bda01e removed separate remark support entirely, but
it turns out we can just drop the parameter and everything appears to
work fine.
Fixesrust-lang/rust#146912 as far as I can tell (the test passes.)
Add attributes for #[global_allocator] functions
Emit `#[rustc_allocator]` etc. attributes on the functions generated by the `#[global_allocator]` macro, which will emit LLVM attributes like `"alloc-family"`. If the module with the global allocator participates in LTO, this ensures that the attributes typically emitted on the allocator declarations are not lost if the definition is imported.
There is a similar issue when the allocator shim is used, but I've opted not to fix that case in this PR, because doing that cleanly is somewhat gnarly.
Related to https://github.com/rust-lang/rust/issues/145995.
f16_f128: enable some more tests in Miri
For some reason, a bunch of tests were disabled in Miri that don't use any fancy intrinsics. Let's enable them.
I verified this with `./x miri library/core --no-doc -- float`.
r? `@tgross35`
Add an attribute to check the number of lanes in a SIMD vector after monomorphization
Allows std::simd to drop the `LaneCount<N>: SupportedLaneCount` trait and maintain good error messages.
Also, extends rust-lang/rust#145967 by including spans in layout errors for all ADTs.
r? ``@RalfJung``
cc ``@workingjubilee`` ``@programmerjake``
Add `std` support for `armv7a-vex-v5`
This PR adds standard library support for the VEX V5 Brain (`armv7a-vex-v5` target). It is more-or-less an updated version of the library-side work done in rust-lang/rust#131530.
This was a joint effort between me, `@lewisfm,` `@max-niederman,` `@Gavin-Niederman` and several other members of the [`vexide` project](https://github.com/vexide/).
## Background
VEXos is a fairly unconventional operating system, with user code running in a restricted enviornment with regards to I/O capabilities and whatnot. As such, several OS-dependent APIs are unsupported or have partial support (such as `std::net`, `std::process`, and most of `std::thread`). A more comprehensive list of what does or doesn't work is outlined in the [updated target documentation](https://github.com/vexide/rust/blob/vex-std/src/doc/rustc/src/platform-support/armv7a-vex-v5.md). Despite these limitations, we believe that `libstd` support on this target still has value to users, especially given the popular use of this hardware for educational purposes. For some previous discussion on this matter, see [this comment](https://github.com/rust-lang/rust/pull/131530#issuecomment-2432856841).
## SDK Linkage
VEXos doesn't really ship with an official `libc` or POSIX-style platform API (and though it does port newlib, these are stubbed on top of the underlying SDK). Instead, VEX provides their own SDK for calling platform APIs. Their official SDK is kept proprietary (with public headers), though open-source implementations exist. Following the precedent of the `armv6k-nintendo-3ds` team's work in rust-lang/rust#95897, we've opted not to directly link `libstd` to any SDK with the expectation that users will provide their own with one of the following options:
- [`vex-sdk-download`](https://github.com/vexide/vex-sdk/tree/main/packages/vex-sdk-download), which downloads an official proprietary SDK from VEX using a build script.
- [`vex-sdk-jumptable`](https://crates.io/crates/vex-sdk-jumptable), which is a compatible, open-source reimplementation of the SDK using firmware jumps.
- [`vex-sdk-pros`](https://github.com/vexide/vex-sdk/tree/main/packages/vex-sdk-pros), which uses the [PROS kernel](https://github.com/purduesigbots/pros) as a provider for SDK functions.
- Linking their own implementation or stubbing the functions required by libstd.
The `vex-sdk` crate used in the VEXos PAL provides `libc`-style FFI bindings for any compatible system library, so any of these options *should* work fine. A functional demo project using `vex-sdk-download` can be found [here](https://github.com/vexide/armv7a-vex-v5-demo/tree/main).
## Future Work
This PR implements virtually everything we are currently able to implement given the current capabilities of the platform. The exception to this is file directory enumeration, though the implementation of that is sufficiently [gross enough](c6c5bad11e/packages/vexide-core/src/fs/mod.rs (L987)) to drive us away from supporting this officially.
Additionally, I have a working branch implementing the `panic_unwind` runtime for this target, which is something that would be nice to see in the future, though given the volume of compiler changes i've deemed it out-of-scope for this PR.
Do not materialise X in [X; 0] when X is unsizing a const
Fixrust-lang/rust#143671
It turns out that MIR builder materialise `X` in `[X; 0]` into a temporary local when `X` is unsizing a `const`. This led to a confusing call to destructor of `X` when such a destructor is declared. [Playground](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2024&gist=8dfc933af89efeb89c881bc77498ba63)
This patch may miss out other cases that we should avoid materialisation in case of `[X; 0]`. Suggestions to include is most welcome!
RawVecInner: add missing `unsafe` to unsafe fns
Some (module-private) functions in `library/alloc/src/raw_vec/mod.rs` are unsafe (i.e. may cause UB when called from safe code) but are not marked `unsafe`. Specifically:
- `RawVecInner::grow_exact` causes UB if called with `len` and `additional` arguments such that `len + additional` is less than the current capacity. Indeed, in that case it calls [Allocator::grow](https://doc.rust-lang.org/std/alloc/trait.Allocator.html#method.grow) with a `new_layout` that is smaller than `old_layout`, which violates a safety precondition.
- The RawVecInner methods for resizing the buffer cause UB if called with an `elem_layout` different from the one used to initially allocate the buffer, because in that case `Allocator::grow` or `Allocator::shrink` are called with an `old_layout` that does not *fit* the allocated block, which violates a safety precondition.
- `RawVecInner::current_memory` might cause UB if called with an `elem_layout` different from the one used to initially allocate the buffer, because the `unchecked_mul` might overflow.
- Furthermore, these methods cause UB if called with an `elem_layout` where the size is not a multiple of the alignment. This is because `Layout::repeat` is used (in `layout_array`) to compute the allocation's layout when allocating, which includes padding to ensure alignment of array elements, but simple multiplication is used (in `current_memory`) to compute the old allocation's layout when resizing or deallocating, which would cause the layout used to resize or deallocate to not *fit* the allocated block, which violates a safety precondition.
I discovered these issues while performing formal verification of `library/alloc/src/raw_vec/mod.rs` per [Challenge 19](https://model-checking.github.io/verify-rust-std/challenges/0019-rawvec.html) of the [AWS Rust Standard Library Verification Contest](https://aws.amazon.com/blogs/opensource/verify-the-safety-of-the-rust-standard-library/).
Rollup of 7 pull requests
Successful merges:
- rust-lang/rust#146556 (Fix duration_since panic on unix when std is built with integer overflow checks)
- rust-lang/rust#146679 (Clarify Display for error should not include source)
- rust-lang/rust#146753 (Improve the pretty print of UnstableFeature clause)
- rust-lang/rust#146894 (Improve derive suggestion of const param)
- rust-lang/rust#146950 (core: simplify `CStr::default()`)
- rust-lang/rust#146958 (Fix infinite recursion in Path::eq with String)
- rust-lang/rust#146971 (fix ICE in writeback due to bound regions)
r? `@ghost`
`@rustbot` modify labels: rollup
Memory was allocated via `Box::leak` and thence intended to be tracked
and deallocated manually, but the allocator was also leaked, not
tracked, and never dropped. Now it is dropped immediately.
According to my reading of the `Allocator` trait, if a copy of the
allocator remains live, then its allocations must remain live. Since
the B-tree has a copy of the allocator that will only be dropped after
the nodes, it's safe to not store the allocator in each node (which
would be a much more intrusive change).
Although the examples below this list do imply that there's an impl of
`ToSocketAddrs` for `&[SocketAddr]`, it's not actually noted in the list
of default implementations.
Improve derive suggestion of const param
Make the suggestion not to remove the adt and use the name of the adt variant in the diagnostic.
r? `@BoxyUwU`
