Rollup of 6 pull requests
Successful merges:
- #130042 (properly handle EOF in BufReader::peek)
- #130061 (Add `NonNull` convenience methods to `Box` and `Vec`)
- #130202 (set `download-ci-llvm = true` by default on "library" and "tools" profiles)
- #130214 (MaybeUninit::zeroed: mention that padding is not zeroed)
- #130353 (Make some lint doctests compatible with `--stage=0`)
- #130370 (unstable-book: `trait_upcasting` example should not have `#![allow(incomplete_features)]`)
r? `@ghost`
`@rustbot` modify labels: rollup
This is a follow-up to #123159, but applied to Armv8-R.
This required https://github.com/llvm/llvm-project/pull/88287 to work
properly. Now that this change exists in rustc's llvm, we can fix
Armv8-R's default fpu features. In Armv8-R's case, the default features
from LLVM for floating-point are sufficient, because there is no
integer-only variant of this architecture.
unstable-book: `trait_upcasting` example should not have `#![allow(incomplete_features)]`
Tracking issue: #65991
`trait_upcasting` is not currently an incomplete feature; therefore examples of its use do not require `#![allow(incomplete_features)]`.
Make some lint doctests compatible with `--stage=0`
Currently, running `x test compiler --stage=0` (with `rust.parallel-compiler=false` to avoid other problems) results in two failures, because these lint doctests aren't compatible with the current stage0 compiler.
In theory, the more “correct” solution would be to wrap the opening triple-backtick line in `#[cfg_attr(not(bootstrap), doc = "..."]`. However, that causes a few practical problems:
- `tidy` doesn't understand that syntax, and miscounts the number of backticks in the comment block.
- `lint-docs` doesn't understand that syntax, and thinks it's trying to declare the lint name.
- Working around the above problems would cause more work and more confusion for whoever does the next bootstrap beta bump.
So instead this PR adds some bootstrap gates inside the individual doctests, which end up producing the desired behaviour, and are straightforward to remove.
set `download-ci-llvm = true` by default on "library" and "tools" profiles
It's very rare for developers to need to modify LLVM, so "if-unchanged" isn't a good default for "tools" and "library" profiles since it fetches the LLVM submodule to track changes.
Add `NonNull` convenience methods to `Box` and `Vec`
Implements the ACP: https://github.com/rust-lang/libs-team/issues/418.
The docs for the added methods are mostly copied from the existing methods that use raw pointers instead of `NonNull`.
I'm new to this "contributing to rustc" thing, so I'm sorry if I did something wrong. In particular, I don't know what the process is for creating a new unstable feature. Please advise me if I should do something. Thank you.
stabilize `const_extern_fn`
closes https://github.com/rust-lang/rust/issues/64926
tracking issue: https://github.com/rust-lang/rust/issues/64926
reference PR: https://github.com/rust-lang/reference/pull/1596
## Stabilizaton Report
### Summary
Using `const extern "Rust"` and `const extern "C"` was already stabilized (since version 1.62.0, see https://github.com/rust-lang/rust/pull/95346). This PR stabilizes the other calling conventions: it is now possible to write `const unsafe extern "calling-convention" fn` and `const extern "calling-convention" fn` for any supported calling convention:
```rust
const extern "C-unwind" fn foo1(val: u8) -> u8 { val + 1}
const extern "stdcall" fn foo2(val: u8) -> u8 { val + 1}
const unsafe extern "C-unwind" fn bar1(val: bool) -> bool { !val }
const unsafe extern "stdcall" fn bar2(val: bool) -> bool { !val }
```
This can be used to const-ify an `extern fn`, or conversely, to make a `const fn` callable from external code.
r? T-lang
cc `@RalfJung`
const-eval interning: accept interior mutable pointers in final value
…but keep rejecting mutable references
This fixes https://github.com/rust-lang/rust/issues/121610 by no longer firing the lint when there is a pointer with interior mutability in the final value of the constant. On stable, such pointers can be created with code like:
```rust
pub enum JsValue {
Undefined,
Object(Cell<bool>),
}
impl Drop for JsValue {
fn drop(&mut self) {}
}
// This does *not* get promoted since `JsValue` has a destructor.
// However, the outer scope rule applies, still giving this 'static lifetime.
const UNDEFINED: &JsValue = &JsValue::Undefined;
```
It's not great to accept such values since people *might* think that it is legal to mutate them with unsafe code. (This is related to how "infectious" `UnsafeCell` is, which is a [wide open question](https://github.com/rust-lang/unsafe-code-guidelines/issues/236).) However, we [explicitly document](https://doc.rust-lang.org/reference/behavior-considered-undefined.html) that things created by `const` are immutable. Furthermore, we also accept the following even more questionable code without any lint today:
```rust
let x: &'static Option<Cell<i32>> = &None;
```
This is even more questionable since it does *not* involve a `const`, and yet still puts the data into immutable memory. We could view this as promotion [potentially introducing UB](https://github.com/rust-lang/unsafe-code-guidelines/issues/493). However, we've accepted this since ~forever and it's [too late to reject this now](https://github.com/rust-lang/rust/pull/122789); the pattern is just too useful.
So basically, if you think that `UnsafeCell` should be tracked fully precisely, then you should want the lint we currently emit to be removed, which this PR does. If you think `UnsafeCell` should "infect" surrounding `enum`s, the big problem is really https://github.com/rust-lang/unsafe-code-guidelines/issues/493 which does not trigger the lint -- the cases the lint triggers on are actually the "harmless" ones as there is an explicit surrounding `const` explaining why things end up being immutable.
What all this goes to show is that the hard error added in https://github.com/rust-lang/rust/pull/118324 (later turned into the future-compat lint that I am now suggesting we remove) was based on some wrong assumptions, at least insofar as it concerns shared references. Furthermore, that lint does not help at all for the most problematic case here where the potential UB is completely implicit. (In fact, the lint is actively in the way of [my preferred long-term strategy](https://github.com/rust-lang/unsafe-code-guidelines/issues/493#issuecomment-2028674105) for dealing with this UB.) So I think we should go back to square one and remove that error/lint for shared references. For mutable references, it does seem to work as intended, so we can keep it. Here it serves as a safety net in case the static checks that try to contain mutable references to the inside of a const initializer are not working as intended; I therefore made the check ICE to encourage users to tell us if that safety net is triggered.
Closes https://github.com/rust-lang/rust/issues/122153 by removing the lint.
Cc `@rust-lang/opsem` `@rust-lang/lang`
ci: add a runner for vanilla LLVM 19
Ubuntu 24.10 has `llvm-19` packages that we can start testing with.
The `Dockerfile` is otherwise the same as the `llvm-18` runner.
Fix `Parser::break_up_float`'s right span
```rs
use std::mem::offset_of;
fn main() {
offset_of!((u8,), 0.0);
}
```
Before:
```
error[E0609]: no field `0` on type `u8`
--> ./main.rs:4:25
|
4 | offset_of!((u8,), 0.0);
| _____--------------------^-
| | |
| | in this macro invocation
5 | | }
... |
|
= note: this error originates in the macro `offset_of` (in Nightly builds, run with -Z macro-backtrace for more info)
error: aborting due to 1 previous error
```
After:
```
error[E0609]: no field `0` on type `u8`
--> ./main.rs:4:25
|
4 | offset_of!((u8,), 0.0);
| ^
error: aborting due to 1 previous error
```
---
`@rustbot` label +A-parser +D-imprecise-spans
Stabilize entry_insert
This stabilises `HashMap::Entry::insert_entry`, following the FCP in tracking issue #65225.
This was implemented in #64656 five years ago.
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.
coverage: Extract `executor::block_on` from several async coverage tests
By moving `block_on` to an auxiliary crate, we avoid having to keep a separate copy of it in every async test.
Simplify the canonical clone method and the copy-like forms to copy
Fixes#128081.
The optimized clone method ends up as the following MIR:
```
_2 = copy ((*_1).0: i32);
_3 = copy ((*_1).1: u64);
_4 = copy ((*_1).2: [i8; 3]);
_0 = Foo { a: move _2, b: move _3, c: move _4 };
```
We can transform this to:
```
_0 = copy (*_1);
```
r? `@cjgillot`
Fix `SDKROOT` ignore on macOS
`rustc` has code to detect when `SDKROOT` is obviously set for the wrong platform, so that it can choose to ignore it. This is a pretty important feature for Cargo build scripts and proc macros, since you will often have `SDKROOT` set to an iOS platform there.
However, the code was checking for an old SDK version name `"macosx10.15"` that was previously configured by `add_apple_sdk`, but nowadays configured to the correct `"macosx"`. I think this error was introduced in part https://github.com/rust-lang/rust/pull/77202 and in https://github.com/rust-lang/rust/pull/100286.
Fixes part of https://github.com/rust-lang/rust/issues/80817 (linking with `-Clinker=ld` now works), though more work is still needed in this area, see also https://github.com/rust-lang/rust/issues/129432.
``@rustbot`` label O-macos A-cross
(fix) conflicting negative impl marker
## Context
This MR fixes the error message for conflicting negative trait impls by adding the corresponding the polarity marker to the trait name.
## Issues
- closes#70849
r? `@fmease`
small_data_threshold.rs: Adapt to LLVM head changes
When compiled against LLVM head, `small_data_threshold.rs` [fails with](https://buildkite.com/llvm-project/rust-llvm-integrate-prototype/builds/31051#0191e508-f11d-437b-a4a0-5e18247debc9):
```
/.../small_data_threshold.rs:61:12: error: RISCV: expected string not found in input
--
| //@ RISCV: .section .sdata,
| ^
| /.../small_data_threshold.s:1:1: note: scanning from here
| .text
| ^
| /.../small_data_threshold.s:6:2: note: possible intended match here
| .section .sdata.U,"aw",`@progbits`
| ^
```
I don't know how exactly the current output looks like, or if there was a specific reason for including the trailing comma on the first line.
I only saw a failure for RISCV, but it seemed sensible to adjust MIPS as well.
CI passes with this patch applied: https://buildkite.com/llvm-project/rust-llvm-integrate-prototype/builds/31053
`@rustbot` label: +llvm-main
cc `@paulmenage`
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`.
Failing to do this results in the lint example output complaining
about the lint not existing instead of the thing the lint is supposed
to be complaining about.
