improve process::abort rendering in Miri backtraces
Also, avoid using the `sys` function directly in the panic machinery -- that seems like an unnecessary layering violation.
stabilize c-style varargs for sysv64, win64, efiapi, aapcs
This has been split up so the PR now only contains the extended_varargs_abi_support stabilization; "system" has been moved to https://github.com/rust-lang/rust/pull/145954.
**Previous (combined) PR description:**
This stabilizes extern block declarations of variadic functions with the system, sysv64, win64, efiapi, aapcs ABIs. This corresponds to the extended_varargs_abi_support and extern_system_varargs feature gates.
The feature gates were split up since it seemed like there might be further discussion needed for what exactly "system" ABI variadic functions should do, but a [consensus](https://github.com/rust-lang/rust/issues/136946#issuecomment-2967847553) has meanwhile been reached: they shall behave like "C" functions. IOW, the ABI of a "system" function is (bold part is new in this PR):
- "stdcall" for win32 targets **for non-variadic functions**
- "C" for everything else
This had been previously stabilized *without FCP* in https://github.com/rust-lang/rust/pull/116161, which got reverted in https://github.com/rust-lang/rust/pull/136897. There was also a "fun" race condition involved with the system ABI being [added](https://github.com/rust-lang/rust/pull/119587) to the list of variadic-supporting ABIs between the creation and merge of rust-lang/rust#116161.
There was a question raised [here](https://github.com/rust-lang/rust/pull/116161#issuecomment-1983829513) whether t-lang even needs to be involved for a change like this. Not sure if that has meanwhile been clarified? The behavior of the "system" ABI (a Rust-specific ABI) definitely feels like t-lang territory to me.
Fixesrust-lang/rust#100189
Cc `@rust-lang/lang`
# Stabilization report
> ## General design
> ### What is the RFC for this feature and what changes have occurred to the user-facing design since the RFC was finalized?
AFAIK there is no RFC. The tracking issues are
- https://github.com/rust-lang/rust/issues/100189
- https://github.com/rust-lang/rust/issues/136946
> ### What behavior are we committing to that has been controversial? Summarize the major arguments pro/con.
The only controversial point is whether "system" ABI functions should support variadics.
- Pro: This allows crates like windows-rs to consistently use "system", see e.g. https://github.com/microsoft/windows-rs/issues/3626.
- Cons: `@workingjubilee` had some implementation concerns, but I think those have been [resolved](https://github.com/rust-lang/rust/issues/136946#issuecomment-2967847553). EDIT: turns out Jubilee still has concerns (she mentioned that in a DM); I'll let her express those.
Note that "system" is already a magic ABI we introduced to "do the right thing". This just makes it do the right thing in more cases. In particular, it means that on Windows one can almost always just do
```rust
extern "system" {
// put all the things here
}
```
and it'll do the right thing, rather than having to split imports into non-varargs and varargs, with the varargs in a separate `extern "C"` block (and risking accidentally putting a non-vararg there).
(I am saying "almost" always because some Windows API functions actually use cdecl, not stdcall, on x86. Those of course need to go in `extern "C"` blocks.)
> ### Are there extensions to this feature that remain unstable? How do we know that we are not accidentally committing to those?
Actually defining variadic functions in Rust remains unstable, under the [c_variadic feature gate](https://github.com/rust-lang/rust/issues/44930).
> ## Has a Call for Testing period been conducted? If so, what feedback was received?
>
> Does any OSS nightly users use this feature? For instance, a useful indication might be "search <grep.app> for `#![feature(FEATURE_NAME)]` and had `N` results".
There was no call for testing.
A search brings up https://github.com/rust-osdev/uefi-rs/blob/main/uefi-raw/src/table/boot.rs using this for "efiapi". This doesn't seem widely used, but it is an "obvious" gap in our support for c-variadics.
> ## Implementation quality
All rustc does here is forward the ABI to LLVM so there's lot a lot to say here...
> ### Summarize the major parts of the implementation and provide links into the code (or to PRs)
>
> An example for async closures: <https://rustc-dev-guide.rust-lang.org/coroutine-closures.html>.
The check for allowed variadic ABIs is [here](9c870d30e2/compiler/rustc_hir_analysis/src/lib.rs (L109-L126)).
The special handling of "system" is [here](c24914ec83/compiler/rustc_target/src/spec/abi_map.rs (L82-L85)).
> ### Summarize existing test coverage of this feature
>
> Consider what the "edges" of this feature are. We're particularly interested in seeing tests that assure us about exactly what nearby things we're not stabilizing.
>
> Within each test, include a comment at the top describing the purpose of the test and what set of invariants it intends to demonstrate. This is a great help to those reviewing the tests at stabilization time.
>
> - What does the test coverage landscape for this feature look like?
> - Tests for compiler errors when you use the feature wrongly or make mistakes?
> - Tests for the feature itself:
> - Limits of the feature (so failing compilation)
> - Exercises of edge cases of the feature
> - Tests that checks the feature works as expected (where applicable, `//@ run-pass`).
> - Are there any intentional gaps in test coverage?
>
> Link to test folders or individual tests (ui/codegen/assembly/run-make tests, etc.).
Prior PRs add a codegen test for all ABIs and tests actually calling extern variadic functions for sysv64 and win64:
- https://github.com/rust-lang/rust/pull/144359
- https://github.com/rust-lang/rust/pull/144379
We don't have a way of executing uefi target code in the test suite, so it's unclear how to fully test efiapi. aapcs could probably be done? (But note that we have hardly an such actually-calling-functions tests for ABI things, we almost entirely rely on codegen tests.)
The test ensuring that we do *not* stabilize *defining* c-variadic functions is `tests/ui/feature-gates/feature-gate-c_variadic.rs`.
> ### What outstanding bugs in the issue tracker involve this feature? Are they stabilization-blocking?
None that I am aware of.
> ### What FIXMEs are still in the code for that feature and why is it ok to leave them there?
None that I am aware of.
> ### Summarize contributors to the feature by name for recognition and assuredness that people involved in the feature agree with stabilization
`@Soveu` added sysv64, win64, efiapi, aapcs to the list of ABIs that allow variadics, `@beepster4096` added system. `@workingjubilee` recently refactored the ABI handling in the compiler, also affecting this feature.
> ### Which tools need to be adjusted to support this feature. Has this work been done?
>
> Consider rustdoc, clippy, rust-analyzer, rustfmt, rustup, docs.rs.
Maybe RA needs to be taught about the new allowed ABIs? No idea how precisely they mirror what exactly rustc accepts and rejects here.
> ## Type system and execution rules
> ### What compilation-time checks are done that are needed to prevent undefined behavior?
>
> (Be sure to link to tests demonstrating that these tests are being done.)
Nothing new here, this just expands the existing support for calling variadic functions to more ABIs.
> ### Does the feature's implementation need checks to prevent UB or is it sound by default and needs opt in in places to perform the dangerous/unsafe operations? If it is not sound by default, what is the rationale?
Nothing new here, this just expands the existing support for calling variadic functions to more ABIs.
> ### Can users use this feature to introduce undefined behavior, or use this feature to break the abstraction of Rust and expose the underlying assembly-level implementation? (Describe.)
Nothing new here, this just expands the existing support for calling variadic functions to more ABIs.
> ### What updates are needed to the reference/specification? (link to PRs when they exist)
- https://github.com/rust-lang/reference/pull/1936
> ## Common interactions
> ### Does this feature introduce new expressions and can they produce temporaries? What are the lifetimes of those temporaries?
No.
> ### What other unstable features may be exposed by this feature?
None.
Rollup of 5 pull requests
Successful merges:
- rust-lang/rust#145468 (dedup recip, powi, to_degrees, and to_radians float tests)
- rust-lang/rust#145643 (coverage: Build an "expansion tree" and use it to unexpand raw spans)
- rust-lang/rust#145754 (fix(lexer): Don't require frontmatters to be escaped with indented fences)
- rust-lang/rust#146060 (fixup nix dev shell again)
- rust-lang/rust#146068 (compiletest: Capture panic messages via a custom panic hook)
r? `@ghost`
`@rustbot` modify labels: rollup
dedup recip, powi, to_degrees, and to_radians float tests
Deduplicates recip, powi, to_degrees, and to_radians float tests.
I had to fiddle and slightly increase the tolerances for a few comparisons, so maybe not all of the tests are worth deduplicating.
Part of rust-lang/rust#141726.
Best reviewed commit-by-commit.
r? `@tgross35`
Add `Bound::copied`
Tracking Issue: https://github.com/rust-lang/rust/issues/145966
Some questions:
- [x] Should I update the documentation for `cloned` to actual used a `Clone` type instead of an integer?
- [x] I removed the `must_use` since this is a cheap copy, does that make sense?
Clarify that align_offset overaligns
The current documentation is not clear whether adding `a` to a pointer overaligns (align up) or underaligns (align down).
It should say this explicitly.
cc `@nagisa`
Fix format string grammar in docs and improve alignment error message for #144023
This PR improves error messages and documentation for format strings involving alignment and formatting traits.
Highlights:
- Clearer error messages for invalid alignment specifiers (e.g., `{0:#X>18}`), showing the expected `<`, `^`, or `>` and a working example:
println!("{0:>#18X}", value);
- Updated UI test `format-alignment-hash.rs` to reflect the improved error output.
- Documentation clarification: ensures examples correctly show how width, alignment, and traits like `x`, `X`, `#` combine.
Motivation:
Previously, using `#` with alignment and width produced confusing errors. This PR guides users on the correct syntax and provides actionable examples.
Testing:
- Built the compiler (`./x build`)
- Blessed and ran UI tests (`./x. test src/test/ui/fmt/format-alignment-hash.rs --bless`)
- Verified full test suite passes (`./x test`)
Issue: rust-lang/rust#144023
Ensure consistent drop for panicking drop in hint::select_unpredictable
There are a few alternatives to the implementation. The principal problem is that the selected value must be owned (in the sense of having a drop flag of sorts) when the unselected value is dropped, such that panic unwind goes through the drop of both. This ownership must then be passed on in return when the drop went smoothly.
The basic way of achieving this is by extracting the selected value first, at the cost of relying on the optimizer a little more for detecting the copy as constructing the return value despite having a place in the body. Unfortunately, that causes LLVM to discard the !unpredictable annotation (for some reason that is beyond my comprehension of LLVM).
<details>
<summary>Extract from the build log showing an unannotated select being used</summary>
```
2025-08-09T16:51:06.8790764Z 39: define noundef i64 `@test_int2(i1` noundef zeroext %p, i64 noundef %a, i64 noundef %b) unnamed_addr #0 personality ptr `@rust_eh_personality` {
2025-08-09T16:51:06.8791368Z check:47'0 X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
2025-08-09T16:51:06.8791700Z 40: start:
2025-08-09T16:51:06.8791858Z check:47'0 ~~~~~~~
2025-08-09T16:51:06.8792043Z 41: %ret.i = select i1 %p, i64 %a, i64 %b
2025-08-09T16:51:06.8792293Z check:47'0 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2025-08-09T16:51:06.8792686Z check:47'1 ? possible intended match
2025-08-09T16:51:06.8792946Z 42: ret i64 %ret.i
2025-08-09T16:51:06.8793127Z check:47'0 ~~~~~~~~~~~~~~~~
```
</details>
So instead, this PR includes a guard to drop the selected `MaybeUnit<T>` which is active only for the section where the unselected value is dropped. That leaves the code for selecting the result intact leading to the expected ir. That complicates the 'unselection' process a little bit since we require _both_ values as a result of that intrinsic call. Since the arguments alias, this portion as well as the drop guard uses raw pointers.
Closes: rust-lang/rust#145148
Prior: rust-lang/rust#139977
Fix `sys::process::windows::tests::test_thread_handle` spurious failure
Instead of sleeping, wait for the process to finish so that we can be sure it's done. We use a timeout because otherwise this test can be stuck indefinitely if it fails (unfortunately std doesn't currently have a way to wait with a timeout so a manual OS API call is necessary).
I also changed the test to run `whoami` and pipe the output to null so that it doesn't clutter up the test output.
Fixesrust-lang/rust#146024
Hard-code `char::is_control`
Split off from https://github.com/rust-lang/rust/pull/145219
According to
https://www.unicode.org/policies/stability_policy.html#Property_Value, the set of codepoints in `Cc` will never change. So we can hard-code the patterns to match against instead of using a table.
This doesn't change the generated assembly, since the lookup table is small enough that[ LLVM is able to inline the whole search](https://godbolt.org/z/bG8dM37YG). But this does reduce the chance of regressions if LLVM's heuristics change in the future, and means less generated Rust code checked in to `unicode-data.rs`.
Previously, attempting to create/truncate a file without write/append access
would result in platform-specific error messages:
- Unix: "Invalid argument"
- Windows: raw OS error code 87
These error codes look like system errors, which could waste hours
of debugging for what is actually an API misuse issue.
Instead of a tuple, select the dropped value and its guard with two
separate calls to the intrinsic which makes both calls have a
pointer-valued argument that should be simpler in codegen. Use the same
condition on all (not an inverted condition) to clarify the intent of
parallel selection. This should also be a simpler value-dependency chain
if the guard is deduced unused (i.e. drop_in_place a noop for the type).
Optimize `.ilog({2,10})` to `.ilog{2,10}()`
Optimize `.ilog({2,10})` to `.ilog{2,10}()`
Inform compiler of optimizations when the base is known at compile time and there's a cheaper method available:
* `{integer}.checked_ilog(2)` -> `{integer}.checked_ilog2()`
* `{integer}.checked_ilog(10)` -> `{integer}.checked_ilog10()`
* `{integer}.ilog(2)` -> `{integer}.ilog2()`
* `{integer}.ilog(10)` -> `{integer}.ilog10()`
Implementation: `#[feature(nonpoison_condvar)]`
Tracking Issue: https://github.com/rust-lang/rust/issues/134645
This PR continues the effort made in https://github.com/rust-lang/rust/pull/144022 by adding the implementation of `nonpoison::condvar`.
Many of the changes here are similar to the changes made to implement `nonpoison::mutex`.
There are two other changes here. The first is that the `Barrier` implementation is migrated to use the `nonpoison::Condvar` instead of the `poison` variant. The second (which might be subject to some discussion) is that `WaitTimeoutResult` is moved up to `mod.rs`, as both `condvar` variants need that type (and I do not know if there is a better place to put it now).
### Related PRs
- `nonpoison_rwlock` implementation: https://github.com/rust-lang/rust/pull/144648
- `nonpoison_once` implementation: https://github.com/rust-lang/rust/pull/144653
fix(lib-std-fs): handle `usize` overflow in `read*`
I assume this is a non-breaking change, as there would be an OOM `panic` anyways. This patch ensures a fast-fail when there's not enough memory to load the file. This only changes behavior on platforms where `usize` is smaller than 64bits
Inform compiler of optimizations when the base is known at compile time
and there's a cheaper method available:
* `{integer}.checked_ilog(2)` -> `{integer}.checked_ilog2()`
* `{integer}.checked_ilog(10)` -> `{integer}.checked_ilog10()`
* `{integer}.ilog(2)` -> `{integer}.ilog2()`
* `{integer}.ilog(10)` -> `{integer}.ilog10()`
fix(std): Fix undefined reference to __my_thread_exit on QNX 8.0
When cross-compiling for the x86_64/aarch64-unknown-nto-qnx800 target (QNX SDP 8.0), the build fails during the final link stage with the error:
```
error: linking with `qcc` failed: exit status: 1
...
= note: undefined reference to `__my_thread_exit'
```
- **On QNX 7.1**: The __my_thread_exit symbol is defined and exported by the main C library (libc.a/libc.so). The std backtrace code can therefore successfully take its address at compile time.
- **On QNX 8.0**: As part of a toolchain modernization, this symbol has been refactored. It is no longer present in any of the standard system libraries (.a or .so).
This patch addresses the problem at its source by conditionally compiling the problematic code.
Fixesrust-lang/rust#142726
