Merge subtree update for toolchain nightly-2025-08-19 #471
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compiler & tools dependencies:
Locking 3 packages to latest compatible versions
Updating ipc-channel v0.20.0 -> v0.20.1
Updating rand v0.9.1 -> v0.9.2
Updating redox_syscall v0.5.13 -> v0.5.16
note: pass `--verbose` to see 37 unchanged dependencies behind latest
library dependencies:
Locking 1 package to latest compatible version
Updating rand v0.9.1 -> v0.9.2
note: pass `--verbose` to see 2 unchanged dependencies behind latest
rustbook dependencies:
Locking 1 package to latest compatible version
Updating redox_syscall v0.5.13 -> v0.5.16
Silence the approximate constant lint because it is noisy and not always correct. `single_component_path_imports` is also not accurate when built as part of `compiler-builtins`, so that needs to be `allow`ed as well.
If `HOME` is empty, use the fallback instead This is a minor change in the `home_dir` api. An empty path is never (or should never be) valid so if the `HOME` environment variable is empty then let's use the fallback instead. r? libs-api
library/windows_targets: Fix macro expansion error in 'link' macro
A recent change altered the definition of the link! macro when the windows_raw_dylib feature is enabled, changing its syntax from pub macro {..} to pub macro($tt:tt) {..} in rust-lang#143592
This change introduced a build failure with the error: "macros that expand to items must be delimited with braces or followed by a semicolon".
We add a semicolon to the line causing the issue as we also modify the non windows_raw_dylib link to make use of the link_dylib macro
Possible workaround for rust-lang/compiler-builtins#976 (comment) Inline assembly in the body of a function currently causes the compiler to consider that function possibly unwinding, even if said asm originated from inlining an `extern "C"` function. This patch wraps the problematic callsite with `#[inline(never)]`.
Fixes: rust-lang/compiler-builtins#837 The assembly is based on - https://github.com/NetBSD/src/blob/20433927938987dd64c8f6aa46904b7aca3fa39e/lib/libm/arch/i387/s_floor.S - https://github.com/NetBSD/src/blob/20433927938987dd64c8f6aa46904b7aca3fa39e/lib/libm/arch/i387/s_ceil.S Which both state /* * Written by J.T. Conklin <[email protected]>. * Public domain. */ Which I believe means we're good in terms of licensing.
Assembly-related configuration was added in 1621c6dbf9eb ("Use
`specialized-div-rem` 1.0.0 for division algorithms") to account for
Cranelift not yet supporting assembly. This hasn't been relevant for a
while, so we no longer need to gate `asm!` behind this configuration.
Thus, remove `cfg(not(feature = "no-asm"))` in places where there is no
generic fallback.
There are other cases, however, where setting the `no-asm` configuration
enables testing of generic version of builtins when there are platform-
specific implementations available; these cases are left unchanged. This
could be improved in the future by exposing both versions for testing
rather than using a configuration and running the entire testsuite
twice.
This is the compiler-builtins portion of
rust-lang#144471.
…r=nikic Don't special-case llvm.* as nounwind Certain LLVM intrinsics, such as `llvm.wasm.throw`, can unwind. Marking them as nounwind causes us to skip cleanup of locals and optimize out `catch_unwind` under inlining or when `llvm.wasm.throw` is used directly by user code. The motivation for forcibly marking llvm.* as nounwind is no longer present: most intrinsics are linked as `extern "C"` or other non-unwinding ABIs, so we won't codegen `invoke` for them anyway. Closes rust-lang#132416. `@rustbot` label +T-compiler +A-panic
…Amanieu
Remove `compiler-builtins-{no-asm,mangled-names}`
Remove `compiler-builtins-no-asm`
This feature used to be for when Cranelift didn't support inline
assembly, but its last uses were removed in 52933e0 ("Don't disable
inline asm usage in compiler-builtins when the cranelift backend is
enabled"). and cba05a7 ("Support naked functions").
This doesn't remove the feature from the `compiler-builtins` crate, that
will be done separately in the subtree repo.
---
Remove `compiler-builtins-mangled-names`
This config was added in 207de01 ("libary: Forward
compiler-builtins "asm" and "mangled-names" feature") but it does not
appear this has ever been used. The PR adding it (rust-lang#78472) says that
this was exposed to help with configuration and points at the [Hermit
Cargo config], but as far as I can tell, this feature name has never
been mentioned in that repository's git history.
Thus, clean up a seemingly unneeded feature.
[Hermit Cargo config]: https://github.com/hermit-os/hermit-rs/blob/ab2b830930e6a9a98c8294997a8183feeabeda4a/.cargo/config
…iaskrgr Rollup of 6 pull requests Successful merges: - rust-lang#143607 (Port the proc macro attributes to the new attribute parsing infrastructure) - rust-lang#144471 (Remove `compiler-builtins-{no-asm,mangled-names}`) - rust-lang#144495 (bump cargo_metadata) - rust-lang#144523 (rustdoc: save target modifiers) - rust-lang#144534 (check_static_item: explain should_check_for_sync choices) - rust-lang#144535 (miri: for ABI mismatch errors, say which argument is the problem) Failed merges: - rust-lang#144536 (miri subtree update) r? `@ghost` `@rustbot` modify labels: rollup
update `Atomic*::from_ptr` and `Atomic*::as_ptr` docs Since rust-lang#128778, it's allowed to perform atomic read and non-atomic read on the same atomic at the same time. Update the `Atomic*::from_ptr` and `Atomic*::as_ptr` documentation to remove expressions such as `not allowed to mix atomic and non-atomic accesses`. see also [std::sync::atomic](https://doc.rust-lang.org/std/sync/atomic/index.html#memory-model-for-atomic-accesses)
…ges, r=Mark-Simulacrum Add a ratchet for moving all standard library tests to separate packages rust-lang#136642 is the previous PR in this series. See rust-lang#135937 for the rationale of wanting to move all standard library tests to separate packages. This also fixes std_detect testing on riscv.
str: Mark unstable `round_char_boundary` feature functions as const Mark `floor_char_boundary`, `ceil_char_boundary` const Simplify the implementations, reducing the number of arithmetic operations It seems unnecessary to do the lower/upper bounds calculations and extra slicing when we can jump straight to inspecting the bytes, assuming the underlying data is valid UTF-8. Tracking issue rust-lang#93743
Fix CI for drop_guard fix CI fix all tidy lints fix tidy link add first batch of feedback from review Add second batch of feedback from review add third batch of feedback from review fix failing test Update library/core/src/mem/drop_guard.rs Co-authored-by: Ruby Lazuli <[email protected]> fix doctests Implement changes from T-Libs-API review And start tracking based on the tracking issue. fix tidy lint
Weekly `cargo update`
Automation to keep dependencies in `Cargo.lock` current.
r? dep-bumps
The following is the output from `cargo update`:
```txt
compiler & tools dependencies:
Locking 3 packages to latest compatible versions
Updating ipc-channel v0.20.0 -> v0.20.1
Updating rand v0.9.1 -> v0.9.2
Updating redox_syscall v0.5.13 -> v0.5.16
note: pass `--verbose` to see 37 unchanged dependencies behind latest
library dependencies:
Locking 1 package to latest compatible version
Updating rand v0.9.1 -> v0.9.2
note: pass `--verbose` to see 2 unchanged dependencies behind latest
rustbook dependencies:
Locking 1 package to latest compatible version
Updating redox_syscall v0.5.13 -> v0.5.16
```
Remove `[T]::array_chunks(_mut)` Since libs-api is proposing as much in rust-lang#74985 (comment) Closes rust-lang#74985 Closes rust-lang#76354 try-job: dist-various-1 try-job: dist-various-2
…ulacrum
Add `core::mem::DropGuard`
## 1.0 Summary
This PR introduces a new type `core::mem::DropGuard` which wraps a value and runs a closure when the value is dropped.
```rust
use core::mem::DropGuard;
// Create a new guard around a string that will
// print its value when dropped.
let s = String::from("Chashu likes tuna");
let mut s = DropGuard::new(s, |s| println!("{s}"));
// Modify the string contained in the guard.
s.push_str("!!!");
// The guard will be dropped here, printing:
// "Chashu likes tuna!!!"
```
## 2.0 Motivation
A number of programming languages include constructs like `try..finally` or `defer` to run code as the last piece of a particular sequence, regardless of whether an error occurred. This is typically used to clean up resources, like closing files, freeing memory, or unlocking resources. In Rust we use the `Drop` trait instead, allowing us to [never having to manually close sockets](https://blog.skylight.io/rust-means-never-having-to-close-a-socket/).
While `Drop` (and RAII in general) has been working incredibly well for Rust in general, sometimes it can be a little verbose to setup. In particular when upholding invariants are local to functions, having a quick inline way to setup an `impl Drop` can be incredibly convenient. We can see this in use in the Rust stdlib, which has a number of private `DropGuard` impls used internally:
- [library/alloc/src/vec/drain.rs](https://github.com/rust-lang/rust/blob/9982d6462bedf1e793f7b2dbd655a4e57cdf67d4/library/alloc/src/vec/drain.rs#L177)
- [library/alloc/src/boxed/thin.rs](https://github.com/rust-lang/rust/blob/9982d6462bedf1e793f7b2dbd655a4e57cdf67d4/library/alloc/src/boxed/thin.rs#L362)
- [library/alloc/src/slice.rs](https://github.com/rust-lang/rust/blob/9982d6462bedf1e793f7b2dbd655a4e57cdf67d4/library/alloc/src/slice.rs#L413)
- [library/alloc/src/collections/linked_list.rs](https://github.com/rust-lang/rust/blob/9982d6462bedf1e793f7b2dbd655a4e57cdf67d4/library/alloc/src/collections/linked_list.rs#L1135)
- [library/alloc/src/collections/binary_heap/mod.rs](https://github.com/rust-lang/rust/blob/9982d6462bedf1e793f7b2dbd655a4e57cdf67d4/library/alloc/src/collections/binary_heap/mod.rs#L1816)
- [library/alloc/src/collections/btree/map.rs](https://github.com/rust-lang/rust/blob/9982d6462bedf1e793f7b2dbd655a4e57cdf67d4/library/alloc/src/collections/btree/map.rs#L1715)
- [library/alloc/src/collections/vec_deque/drain.rs](https://github.com/rust-lang/rust/blob/9982d6462bedf1e793f7b2dbd655a4e57cdf67d4/library/alloc/src/collections/vec_deque/drain.rs#L95)
- [library/alloc/src/vec/into_iter.rs](https://github.com/rust-lang/rust/blob/9982d6462bedf1e793f7b2dbd655a4e57cdf67d4/library/alloc/src/vec/into_iter.rs#L488)
- [library/std/src/os/windows/process.rs](https://github.com/rust-lang/rust/blob/9982d6462bedf1e793f7b2dbd655a4e57cdf67d4/library/std/src/os/windows/process.rs#L320)
- [tests/ui/process/win-proc-thread-attributes.rs](https://github.com/rust-lang/rust/blob/9982d6462bedf1e793f7b2dbd655a4e57cdf67d4/tests/ui/process/win-proc-thread-attributes.rs#L17)
## 3.0 Design
This PR implements what can be considered about the simplest possible design:
1. A single type `DropGuard` which takes both a generic type `T` and a closure `F`.
2. `Deref` + `DerefMut` impls to make it easy to work with the `T` in the guard.
3. An `impl Drop` on the guard which calls the closure `F` on drop.
4. An inherent `fn into_inner` which takes the type `T` out of the guard without calling the closure `F`.
Notably this design does not allow divergent behavior based on the type of drop that has occurred. The [`scopeguard` crate](https://docs.rs/scopeguard/latest/scopeguard/index.html) includes additional `on_success` and `on_onwind` variants which can be used to branch on unwind behavior instead. However [in a lot of cases](rust-lang#143612 (comment)) this doesn’t seem necessary, and using the arm/disarm pattern seems to provide much the same functionality:
```rust
let guard = DropGuard::new((), |s| ...); // 1. Arm the guard
other_function(); // 2. Perform operations
guard.into_inner(); // 3. Disarm the guard
```
`DropGuard` combined with this pattern seems like it should cover the vast majority of use cases for quick, inline destructors. It certainly seems like it should cover all existing uses in the stdlib, as well as all existing uses in crates like [hashbrown](https://github.com/search?q=repo%3Arust-lang%2Fhashbrown%20guard&type=code).
## 4.0 Acknowledgements
This implementation is based on the [mini-scopeguard crate](https://github.com/yoshuawuyts/mini-scopeguard) which in turn is based on the [scopeguard crate](https://docs.rs/scopeguard). The implementations only differ superficially; because of the nature of the problem there is only really one obvious way to structure the solution. And the scopeguard crate got that right!
## 5.0 Conclusion
This PR adds a new type `core::mem::DropGuard` to the stdlib which adds a small convenience helper to create inline destructors with. This would bring the majority of the functionality of the `scopeguard` crate into the stdlib, which is the [49th most downloaded crate](https://crates.io/crates?sort=downloads) on crates.io (387 million downloads).
Given the actual implementation of `DropGuard` is only around 60 lines, it seems to hit that sweet spot of low-complexity / high-impact that makes for a particularly efficient stdlib addition. Which is why I’m putting this forward for consideration; thanks!
…ance, r=oli-obk constify with_exposed_provenance We allow `int as ptr` in const, so it only makes sense to also allow this function. Otherwise, `const fn` can't be ported to use the more explicit exposed provenance APIs. Note that as of today, `with_exposed_provenance` in const is equivalent to `without_provenance`. However, we probably don't want to promise that: if someone does `with_exposed_provenance(MMIO_ADDR)` in const and then uses that pointer at runtime, that is something we should ensure keeps working; if someone does the same with `without_provenance` then I would consider that UB. Tracking: rust-lang#144538 Cc `````@rust-lang/wg-const-eval````` `````@rust-lang/opsem`````
fixed typo chunks->as_chunks Fixes rust-lang#144555 info-: fix typo chunks -> as_chunks This now take us to as_chunks page when clicking on as_chunks link and not to chunks . Thanks .
fix `Atomic*::as_ptr` wording r? `````@RalfJung````` cc rust-lang#144072
…r=jhpratt std: thread: Return error if setting thread stack size fails Currently, when setting the thread stack size fails, it would be rounded up to the nearest multiple of the page size and the code asserts that the next call to `pthread_attr_setstacksize` succeeds. This may be true for glibc, but it isn't true for musl, which not only enforces a minimum stack size, but also a maximum stack size of `usize::MAX / 4 - PTHREAD_STACK_MIN` [1], triggering the assert rather than erroring gracefully. There isn't any way to handle this properly other than bailing out and letting the user know it didn't succeed. [1]: https://git.musl-libc.org/cgit/musl/tree/src/thread/pthread_attr_setstacksize.c#n5
Windows: Replace `GetThreadId`+`GetCurrentThread` with `GetCurrentThreadId` Reference: https://learn.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-getcurrentthreadid
…lnay Add `Default` impls for `Pin`ned `Box`, `Rc`, `Arc` Fixes rust-lang#143688. `@rustbot` label T-libs-api needs-fcp Also needs a crater run, as the `Box` impls could theoretically be breaking due to `#[fundamental]` (though a [cursory search](https://github.com/search?q=%2Fimpl%28%3C.*%3E%29%3F+Default+for+Pin%3C%2F+path%3A*.rs&type=code) suggests this is unlikely to cause issues).
…ls, r=tgross35
Stabilize as_array_of_cells
This PR stabilizes
```rust
impl<T, const N: usize> Cell<[T; N]> {
pub const fn as_array_of_cells(&self) -> &[Cell<T>; N];
}
```
Stabilization report: rust-lang#88248 (comment)
Closes: rust-lang#88248
Implement `#[derive(From)]` Implements the `#[derive(From)]` feature ([tracking issue](rust-lang#144889), [RFC](rust-lang/rfcs#3809)). It allows deriving the `From` impl on structs and tuple structs with exactly one field. Some implementation notes: - I wasn't exactly sure which spans to use in the derive generating code, so I just used `span` everywhere. I don't know if it's the Right Thing To Do. In particular the errors when `#[derive(From)]` is used on a struct with an unsized field are weirdly duplicated. - I had to solve an import stability problem, where if I just added the unstable `macro From` to `core::convert`, previously working code like `use std::convert::From` would suddenly require an unstable feature gate, because rustc would think that you're trying to import the unstable macro. `@petrochenkov` suggested that I add the macro the the core prelude instead. This has worked well, although it only works in edition 2021+. Not sure if I botched the prelude somehow and it should live elsewhere (?). - I had to add `Ty::AstTy`, because the `from` function receives an argument with the type of the single field, and the existing variants of the `Ty` enum couldn't represent an arbitrary type.
…-iter-chain, r=jhpratt Stabilize `core::iter::chain` Closes rust-lang#125964
…ovenance, r=RalfJung Stabilize `const_exposed_provenance` feature This closes [tracking issue](rust-lang#144538) and stabilises `fn with_exposed_provenance` and `fn with_exposed_provenance_mut` in const
"privalage" -> "privilege"
Revert "Partially outline code inside the panic! macro". This reverts rust-lang#115670 Without any tests/benchmarks that show some improvement, it's hard to know whether the change had any positive effect. (And if it did, whether that effect is still achieved today.)
Migrate the standard library from using the external `cfg_if` crate to
using the now-built-in `cfg_select` macro.
This does not yet eliminate the dependency from
`library/std/Cargo.toml`, because while the standard library itself no
longer uses `cfg_if`, it also incorporates the `backtrace` crate, which
does.
Migration assisted by the following vim command (after selecting the
full `cfg_if!` invocation):
```
'<,'>s/\(cfg_if::\)\?cfg_if/cfg_select/ | '<,'>s/^\( *\)} else {/\1}\r\1_ => {/c | '<,'>s/^\( *\)} else if #\[cfg(\(.*\))\] /\1}\r\1\2 => /e | '<,'>s/if #\[cfg(\(.*\))\] {/\1 => {/e
```
This is imperfect, but substantially accelerated the process. This
prompts for confirmation on the `} else {` since that can also appear
inside one of the arms. This also requires manual intervention to handle
any multi-line conditions.
The previous code inside `cfg_if!` wasn't indented, so the conversion to `cfg_select!` left it not indented. Indent it.
const-eval: full support for pointer fragments This fixes rust-lang/const-eval#72 and makes `swap_nonoverlapping` fully work in const-eval by enhancing per-byte provenance tracking with tracking of *which* of the bytes of the pointer this one is. Later, if we see all the same bytes in the exact same order, we can treat it like a whole pointer again without ever risking a leak of the data bytes (that encode the offset into the allocation). This lifts the limitation that was discussed quite a bit in rust-lang#137280. For a concrete piece of code that used to fail and now works properly consider this example doing a byte-for-byte memcpy in const without using intrinsics: ```rust use std::{mem::{self, MaybeUninit}, ptr}; type Byte = MaybeUninit<u8>; const unsafe fn memcpy(dst: *mut Byte, src: *const Byte, n: usize) { let mut i = 0; while i < n { *dst.add(i) = *src.add(i); i += 1; } } const _MEMCPY: () = unsafe { let ptr = &42; let mut ptr2 = ptr::null::<i32>(); // Copy from ptr to ptr2. memcpy(&mut ptr2 as *mut _ as *mut _, &ptr as *const _ as *const _, mem::size_of::<&i32>()); assert!(*ptr2 == 42); }; ``` What makes this code tricky is that pointers are "opaque blobs" in const-eval, we cannot just let people look at the individual bytes since *we don't know what those bytes look like* -- that depends on the absolute address the pointed-to object will be placed at. The code above "breaks apart" a pointer into individual bytes, and then puts them back together in the same order elsewhere. This PR implements the logic to properly track how those individual bytes relate to the original pointer, and to recognize when they are in the right order again. We still reject constants where the final value contains a not-fully-put-together pointer: I have no idea how one could construct an LLVM global where one byte is defined as "the 3rd byte of a pointer to that other global over there" -- and even if LLVM supports this somehow, we can leave implementing that to a future PR. It seems unlikely to me anyone would even want this, but who knows.^^ This also changes the behavior of Miri, by tracking the order of bytes with provenance and only considering a pointer to have valid provenance if all bytes are in the original order again. This is related to rust-lang/unsafe-code-guidelines#558. It means one cannot implement XOR linked lists with strict provenance any more, which is however only of theoretical interest. Practically I am curious if anyone will show up with any code that Miri now complains about - that would be interesting data. Cc `@rust-lang/opsem`
… r=lcnr Print regions in `type_name`. Currently they are skipped, which is a bit weird, and it sometimes causes malformed output like `Foo<>` and `dyn Bar<, A = u32>`. Most regions are erased by the time `type_name` does its work. So all regions are now printed as `'_` in non-optional places. Not perfect, but better than the status quo. `c_name` is updated to trim lifetimes from MIR pass names, so that the `PASS_NAMES` sanity check still works. It is also renamed as `simplify_pass_type_name` and made non-const, because it doesn't need to be const and the non-const implementation is much shorter. The commit also renames `should_print_region` as `should_print_optional_region`, which makes it clearer that it only applies to some regions. Fixes rust-lang#145168. r? `@lcnr`
Fix typo in doc for library/std/src/fs.rs#set_permissions "privalage" -> "privilege". Was reading the docs and have noticed this.
library: Migrate from `cfg_if` to `cfg_select`
Migrate the standard library from using the external `cfg_if` crate to using the now-built-in `cfg_select` macro.
This does not yet eliminate the dependency from `library/std/Cargo.toml`, because while the standard library itself no longer uses `cfg_if`, it also incorporates the `backtrace` crate, which does.
Migration assisted by the following vim command (after selecting the full `cfg_if!` invocation):
```
'<,'>s/\(cfg_if::\)\?cfg_if/cfg_select/ | '<,'>s/^\( *\)} else {/\1}\r\1_ => {/c | '<,'>s/^\( *\)} else if #\[cfg(\(.*\))\] /\1}\r\1\2 => /e | '<,'>s/if #\[cfg(\(.*\))\] {/\1 => {/e
```
This is imperfect, but substantially accelerated the process. This prompts for confirmation on the `} else {` since that can also appear inside one of the arms. This also requires manual intervention to handle any multi-line conditions.
tautschnig
approved these changes
Aug 19, 2025
thanhnguyen-aws
approved these changes
Aug 19, 2025
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This is an automated PR to merge library subtree updates from 2025-08-18 (rust-lang/rust@425a9c0) to 2025-08-19 (rust-lang/rust@9eb4a26), inclusive. This is a clean merge, no conflicts were detected. Do not remove or edit the following annotations:
git-subtree-dir: library
git-subtree-split: b4e28fd