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miri: algebraic intrinsics: bring back float non-determinism
Fixes https://github.com/rust-lang/miri/issues/4289
Cc ```@bjoernager```
r? ```@oli-obk```
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Make thread scheduling fully random
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Stabilize `slice_as_chunks` library feature
~~Draft as this needs #139163 to land first.~~
FCP: https://github.com/rust-lang/rust/issues/74985#issuecomment-2769963395
Methods being stabilized are:
```rust
impl [T] {
const fn as_chunks<const N: usize>(&self) -> (&[[T; N]], &[T]);
const fn as_rchunks<const N: usize>(&self) -> (&[T], &[[T; N]]);
const unsafe fn as_chunks_unchecked<const N: usize>(&self) -> &[[T; N]];
const fn as_chunks_mut<const N: usize>(&mut self) -> (&mut [[T; N]], &mut [T]);
const fn as_rchunks_mut<const N: usize>(&mut self) -> (&mut [T], &mut [[T; N]]);
const unsafe fn as_chunks_unchecked_mut<const N: usize>(&mut self) -> &mut [[T; N]];
}
```
~~(FCP's not done quite yet, but will in another day if I'm counting right.)~~ FCP Complete: https://github.com/rust-lang/rust/issues/74985#issuecomment-2797951535
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Async drop codegen
Async drop implementation using templated coroutine for async drop glue generation.
Scopes changes to generate `async_drop_in_place()` awaits, when async droppable objects are out-of-scope in async context.
Implementation details:
https://github.com/azhogin/posts/blob/main/async-drop-impl.md
New fields in Drop terminator (drop & async_fut). Processing in codegen/miri must validate that those fields are empty (in full version async Drop terminator will be expanded at StateTransform pass or reverted to sync version). Changes in terminator visiting to consider possible new successor (drop field).
ResumedAfterDrop messages for panic when coroutine is resumed after it is started to be async drop'ed.
Lang item for generated coroutine for async function async_drop_in_place. `async fn async_drop_in_place<T>()::{{closure0}}`.
Scopes processing for generate async drop preparations. Async drop is a hidden Yield, so potentially async drops require the same dropline preparation as for Yield terminators.
Processing in StateTransform: async drops are expanded into yield-point. Generation of async drop of coroutine itself added.
Shims for AsyncDropGlueCtorShim, AsyncDropGlue and FutureDropPoll.
```rust
#[lang = "async_drop"]
pub trait AsyncDrop {
#[allow(async_fn_in_trait)]
async fn drop(self: Pin<&mut Self>);
}
impl Drop for Foo {
fn drop(&mut self) {
println!("Foo::drop({})", self.my_resource_handle);
}
}
impl AsyncDrop for Foo {
async fn drop(self: Pin<&mut Self>) {
println!("Foo::async drop({})", self.my_resource_handle);
}
}
```
First async drop glue implementation re-worked to use the same drop elaboration code as for sync drop.
`async_drop_in_place` changed to be `async fn`. So both `async_drop_in_place` ctor and produced coroutine have their lang items (`AsyncDropInPlace`/`AsyncDropInPlacePoll`) and shim instances (`AsyncDropGlueCtorShim`/`AsyncDropGlue`).
```
pub async unsafe fn async_drop_in_place<T: ?Sized>(_to_drop: *mut T) {
}
```
AsyncDropGlue shim generation uses `elaborate_drops::elaborate_drop` to produce drop ladder (in the similar way as for sync drop glue) and then `coroutine::StateTransform` to convert function into coroutine poll.
AsyncDropGlue coroutine's layout can't be calculated for generic T, it requires known final dropee type to be generated (in StateTransform). So, `templated coroutine` was introduced here (`templated_coroutine_layout(...)` etc).
Such approach overrides the first implementation using mixing language-level futures in https://github.com/rust-lang/rust/pull/121801.
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async_drop_in_place::{closure}, scoped async drop added.
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r=jdonszelmann,traviscross
Implement a lint for implicit autoref of raw pointer dereference - take 2
*[t-lang nomination comment](https://github.com/rust-lang/rust/pull/123239#issuecomment-2727551097)*
This PR aims at implementing a lint for implicit autoref of raw pointer dereference, it is based on #103735 with suggestion and improvements from https://github.com/rust-lang/rust/pull/103735#issuecomment-1370420305.
The goal is to catch cases like this, where the user probably doesn't realise it just created a reference.
```rust
pub struct Test {
data: [u8],
}
pub fn test_len(t: *const Test) -> usize {
unsafe { (*t).data.len() } // this calls <[T]>::len(&self)
}
```
Since #103735 already went 2 times through T-lang, where they T-lang ended-up asking for a more restricted version (which is what this PR does), I would prefer this PR to be reviewed first before re-nominating it for T-lang.
----
Compared to the PR it is as based on, this PR adds 3 restrictions on the outer most expression, which must either be:
1. A deref followed by any non-deref place projection (that intermediate deref will typically be auto-inserted)
2. A method call annotated with `#[rustc_no_implicit_refs]`.
3. A deref followed by a `addr_of!` or `addr_of_mut!`. See bottom of post for details.
There are several points that are not 100% clear to me when implementing the modifications:
- ~~"4. Any number of automatically inserted deref/derefmut calls." I as never able to trigger this. Am I missing something?~~ Fixed
- Are "index" and "field" enough?
----
cc `@JakobDegen` `@WaffleLapkin`
r? `@RalfJung`
try-job: dist-various-1
try-job: dist-various-2
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handle function alignment in miri
tracking issue: https://github.com/rust-lang/rust/issues/82232
Fixes https://github.com/rust-lang/miri/issues/4282
The `#[repr(align(N))]` attribute on functions was ignored when using miri. For such a function, its address should be a multiple of `N`.
There is some further discussion in the thread [#t-compiler/const-eval > function address alignment](https://rust-lang.zulipchat.com/#narrow/channel/146212-t-compiler.2Fconst-eval/topic/function.20address.20alignment) on how `dyn Fn` should be handled. The behavior there appears to be consistent between miri and nightly, though both may be incorrect. In any case, that can be resolved separately.
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docs(LocalKey<T>): clarify that T's Drop shouldn't panic
Clarify that should a TLS destructor panics, the process will abort.
Also, an abort may be obfuscated as the process can be terminated with `SIGSEGV` or [`STATUS_STACK_BUFFER_OVERRUN`](https://devblogs.microsoft.com/oldnewthing/20190108-00/?p=100655) (i.e., `SIGABRT` is not guaranteed), so explicitly prints that the process was aborted.
Context:
https://users.rust-lang.org/t/status-stack-buffer-overrun-on-windows-without-any-usage-of-unsafe/128417
``@rustbot`` label -T-compiler
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Do not remove trivial `SwitchInt` in analysis MIR
This PR ensures that we don't prematurely remove trivial `SwitchInt` terminators which affects both the borrow-checking and runtime semantics (i.e. UB) of the code. Previously the `SimplifyCfg` optimization was removing `SwitchInt` terminators when they was "trivial", i.e. when all arms branched to the same basic block, even if that `SwitchInt` terminator had the side-effect of reading an operand which (for example) may not be initialized or may point to an invalid place in memory.
This behavior is unlike all other optimizations, which are only applied after "analysis" (i.e. borrow-checking) is finished, and which Miri disables to make sure the compiler doesn't silently remove UB.
Fixing this code "breaks" (i.e. unmasks) code that used to borrow-check but no longer does, like:
```rust
fn foo() {
let x;
let (0 | _) = x;
}
```
This match expression should perform a read because `_` does not shadow the `0` literal pattern, and the compiler should have to read the match scrutinee to compare it to 0. I've checked that this behavior does not actually manifest in practice via a crater run which came back clean: https://github.com/rust-lang/rust/pull/139042#issuecomment-2767436367
As a side-note, it may be tempting to suggest that this is actually a good thing or that we should preserve this behavior. If we wanted to make this work (i.e. trivially optimize out reads from matches that are redundant like `0 | _`), then we should be enabling this behavior *after* fixing this. However, I think it's kinda unprincipled, and for example other variations of the code don't even work today, e.g.:
```rust
fn foo() {
let x;
let (0.. | _) = x;
}
```
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sync::mpsc: prevent double free on `Drop`
This PR is fixing a regression introduced by #121646 that can lead to a double free when dropping the channel.
The details of the bug can be found in the corresponding crossbeam PR https://github.com/crossbeam-rs/crossbeam/pull/1187
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f*::NAN: guarantee that this is a quiet NaN
I think we should guarantee that this is a quiet NaN. This then implies that programs not using `f*::from_bits` (or unsafe type conversions) are guaranteed to only work with quiet NaNs. It would be awkward if people start to write `0.0 / 0.0` instead of using the constant just because they want to get a guaranteed-quiet NaN.
This is a `@rust-lang/libs-api` change. The definition of this constant currently is `0.0 / 0.0`, which is already guaranteed to be a quiet NaN. So all this does is forward that guarantee to our users.
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Replace check_shim with check_shim_abi in unix/foreign_items shims
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related shims
Making type consistent in shims
pread return type fix
make clock_gettime shim type consistent
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Implement file deletion on Windows
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This PR is fixing a regression introduced by #121646 that can lead to a
double free when dropping the channel.
The details of the bug can be found in the corresponding crossbeam PR
https://github.com/crossbeam-rs/crossbeam/pull/1187
Signed-off-by: Petros Angelatos <petrosagg@gmail.com>
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Signed-off-by: Petros Angelatos <petrosagg@gmail.com>
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Ensure `swap_nonoverlapping` is really always untyped
This replaces #134954, which was arguably overcomplicated.
## Fixes #134713
Actually using the type passed to `ptr::swap_nonoverlapping` for anything other than its size + align turns out to not work, so this goes back to always erasing the types down to just bytes.
(Except in `const`, which keeps doing the same thing as before to preserve `@RalfJung's` fix from #134689)
## Fixes #134946
I'd previously moved the swapping to use auto-vectorization *on bytes*, but someone pointed out on Discord that the tail loop handling from that left a whole bunch of byte-by-byte swapping around. This goes back to manual tail handling to avoid that, then still triggers auto-vectorization on pointer-width values. (So you'll see `<4 x i64>` on `x86-64-v3` for example.)
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Implement RtlNtStatusToDosError and shim test for it
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path: add more Windows tests
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Implement FreeBSD syscall _umtx_op for futex support
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Futex support
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