diff options
| -rw-r--r-- | compiler/rustc_ty_utils/src/layout.rs | 8 | ||||
| -rw-r--r-- | src/tools/miri/tests/pass/async-niche-aliasing.rs | 66 | ||||
| -rw-r--r-- | tests/ui/async-await/async-drop.rs | 26 | ||||
| -rw-r--r-- | tests/ui/async-await/future-sizes/async-awaiting-fut.stdout | 20 | ||||
| -rw-r--r-- | tests/ui/coroutine/discriminant.rs | 6 | ||||
| -rw-r--r-- | tests/ui/coroutine/niche-in-coroutine.rs | 3 |
6 files changed, 102 insertions, 27 deletions
diff --git a/compiler/rustc_ty_utils/src/layout.rs b/compiler/rustc_ty_utils/src/layout.rs index 234e1a6d55e..c23a7fec5a5 100644 --- a/compiler/rustc_ty_utils/src/layout.rs +++ b/compiler/rustc_ty_utils/src/layout.rs @@ -1001,7 +1001,13 @@ fn coroutine_layout<'tcx>( }, fields: outer_fields, abi, - largest_niche: prefix.largest_niche, + // Suppress niches inside coroutines. If the niche is inside a field that is aliased (due to + // self-referentiality), getting the discriminant can cause aliasing violations. + // `UnsafeCell` blocks niches for the same reason, but we don't yet have `UnsafePinned` that + // would do the same for us here. + // See <https://github.com/rust-lang/rust/issues/63818>, <https://github.com/rust-lang/miri/issues/3780>. + // FIXME: Remove when <https://github.com/rust-lang/rust/issues/125735> is implemented and aliased coroutine fields are wrapped in `UnsafePinned`. + largest_niche: None, size, align, max_repr_align: None, diff --git a/src/tools/miri/tests/pass/async-niche-aliasing.rs b/src/tools/miri/tests/pass/async-niche-aliasing.rs new file mode 100644 index 00000000000..7f19afb33e4 --- /dev/null +++ b/src/tools/miri/tests/pass/async-niche-aliasing.rs @@ -0,0 +1,66 @@ +//@revisions: stack tree +//@[tree]compile-flags: -Zmiri-tree-borrows + +use std::{ + future::Future, + pin::Pin, + sync::Arc, + task::{Context, Poll, Wake}, + mem::MaybeUninit, +}; + +struct ThingAdder<'a> { + // Using `MaybeUninit` to ensure there are no niches here. + thing: MaybeUninit<&'a mut String>, +} + +impl Future for ThingAdder<'_> { + type Output = (); + + fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Self::Output> { + unsafe { + **self.get_unchecked_mut().thing.assume_init_mut() += ", world"; + } + Poll::Pending + } +} + +fn main() { + let mut thing = "hello".to_owned(); + // This future has (at least) two fields, a String (`thing`) and a ThingAdder pointing to that string. + let fut = async move { ThingAdder { thing: MaybeUninit::new(&mut thing) }.await }; + + let mut fut = MaybeDone::Future(fut); + let mut fut = unsafe { Pin::new_unchecked(&mut fut) }; + + let waker = Arc::new(DummyWaker).into(); + let mut ctx = Context::from_waker(&waker); + // This ends up reading the discriminant of the `MaybeDone`. If that is stored inside the + // `thing: String` as a niche optimization, that causes aliasing conflicts with the reference + // stored in `ThingAdder`. + assert_eq!(fut.as_mut().poll(&mut ctx), Poll::Pending); + assert_eq!(fut.as_mut().poll(&mut ctx), Poll::Pending); +} + +struct DummyWaker; + +impl Wake for DummyWaker { + fn wake(self: Arc<Self>) {} +} + +pub enum MaybeDone<F: Future> { + Future(F), + Done, +} +impl<F: Future<Output = ()>> Future for MaybeDone<F> { + type Output = (); + + fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> { + unsafe { + match *self.as_mut().get_unchecked_mut() { + MaybeDone::Future(ref mut f) => Pin::new_unchecked(f).poll(cx), + MaybeDone::Done => unreachable!(), + } + } + } +} diff --git a/tests/ui/async-await/async-drop.rs b/tests/ui/async-await/async-drop.rs index 12f120a0b12..4e60598661f 100644 --- a/tests/ui/async-await/async-drop.rs +++ b/tests/ui/async-await/async-drop.rs @@ -53,18 +53,20 @@ fn main() { let i = 13; let fut = pin!(async { test_async_drop(Int(0), 0).await; - test_async_drop(AsyncInt(0), 104).await; - test_async_drop([AsyncInt(1), AsyncInt(2)], 152).await; - test_async_drop((AsyncInt(3), AsyncInt(4)), 488).await; + // FIXME(#63818): niches in coroutines are disabled. + // Some of these sizes should be smaller, as indicated in comments. + test_async_drop(AsyncInt(0), /*104*/ 112).await; + test_async_drop([AsyncInt(1), AsyncInt(2)], /*152*/ 168).await; + test_async_drop((AsyncInt(3), AsyncInt(4)), /*488*/ 528).await; test_async_drop(5, 0).await; let j = 42; test_async_drop(&i, 0).await; test_async_drop(&j, 0).await; - test_async_drop(AsyncStruct { b: AsyncInt(8), a: AsyncInt(7), i: 6 }, 1688).await; + test_async_drop(AsyncStruct { b: AsyncInt(8), a: AsyncInt(7), i: 6 }, /*1688*/ 1792).await; test_async_drop(ManuallyDrop::new(AsyncInt(9)), 0).await; let foo = AsyncInt(10); - test_async_drop(AsyncReference { foo: &foo }, 104).await; + test_async_drop(AsyncReference { foo: &foo }, /*104*/ 112).await; let foo = AsyncInt(11); test_async_drop( @@ -73,17 +75,17 @@ fn main() { let foo = AsyncInt(10); foo }, - 120, + /*120*/ 136, ) .await; - test_async_drop(AsyncEnum::A(AsyncInt(12)), 680).await; - test_async_drop(AsyncEnum::B(SyncInt(13)), 680).await; + test_async_drop(AsyncEnum::A(AsyncInt(12)), /*680*/ 736).await; + test_async_drop(AsyncEnum::B(SyncInt(13)), /*680*/ 736).await; - test_async_drop(SyncInt(14), 16).await; + test_async_drop(SyncInt(14), /*16*/ 24).await; test_async_drop( SyncThenAsync { i: 15, a: AsyncInt(16), b: SyncInt(17), c: AsyncInt(18) }, - 3064, + /*3064*/ 3296, ) .await; @@ -99,11 +101,11 @@ fn main() { black_box(core::future::ready(())).await; foo }, - 120, + /*120*/ 136, ) .await; - test_async_drop(AsyncUnion { signed: 21 }, 32).await; + test_async_drop(AsyncUnion { signed: 21 }, /*32*/ 40).await; }); let res = fut.poll(&mut cx); assert_eq!(res, Poll::Ready(())); diff --git a/tests/ui/async-await/future-sizes/async-awaiting-fut.stdout b/tests/ui/async-await/future-sizes/async-awaiting-fut.stdout index def967ba195..642e27b2a57 100644 --- a/tests/ui/async-await/future-sizes/async-awaiting-fut.stdout +++ b/tests/ui/async-await/future-sizes/async-awaiting-fut.stdout @@ -14,28 +14,26 @@ print-type-size field `.value`: 3077 bytes print-type-size type: `{async fn body of calls_fut<{async fn body of big_fut()}>()}`: 3077 bytes, alignment: 1 bytes print-type-size discriminant: 1 bytes print-type-size variant `Unresumed`: 1025 bytes -print-type-size upvar `.fut`: 1025 bytes, offset: 0 bytes, alignment: 1 bytes +print-type-size upvar `.fut`: 1025 bytes print-type-size variant `Suspend0`: 2052 bytes -print-type-size upvar `.fut`: 1025 bytes, offset: 0 bytes, alignment: 1 bytes -print-type-size padding: 1 bytes -print-type-size local `.fut`: 1025 bytes, alignment: 1 bytes +print-type-size upvar `.fut`: 1025 bytes +print-type-size local `.fut`: 1025 bytes print-type-size local `..coroutine_field4`: 1 bytes, type: bool print-type-size local `.__awaitee`: 1 bytes, type: {async fn body of wait()} print-type-size variant `Suspend1`: 3076 bytes -print-type-size upvar `.fut`: 1025 bytes, offset: 0 bytes, alignment: 1 bytes -print-type-size padding: 1026 bytes +print-type-size upvar `.fut`: 1025 bytes +print-type-size padding: 1025 bytes print-type-size local `..coroutine_field4`: 1 bytes, alignment: 1 bytes, type: bool print-type-size local `.__awaitee`: 1025 bytes, type: {async fn body of big_fut()} print-type-size variant `Suspend2`: 2052 bytes -print-type-size upvar `.fut`: 1025 bytes, offset: 0 bytes, alignment: 1 bytes -print-type-size padding: 1 bytes -print-type-size local `.fut`: 1025 bytes, alignment: 1 bytes +print-type-size upvar `.fut`: 1025 bytes +print-type-size local `.fut`: 1025 bytes print-type-size local `..coroutine_field4`: 1 bytes, type: bool print-type-size local `.__awaitee`: 1 bytes, type: {async fn body of wait()} print-type-size variant `Returned`: 1025 bytes -print-type-size upvar `.fut`: 1025 bytes, offset: 0 bytes, alignment: 1 bytes +print-type-size upvar `.fut`: 1025 bytes print-type-size variant `Panicked`: 1025 bytes -print-type-size upvar `.fut`: 1025 bytes, offset: 0 bytes, alignment: 1 bytes +print-type-size upvar `.fut`: 1025 bytes print-type-size type: `std::mem::ManuallyDrop<{async fn body of big_fut()}>`: 1025 bytes, alignment: 1 bytes print-type-size field `.value`: 1025 bytes print-type-size type: `std::mem::MaybeUninit<{async fn body of big_fut()}>`: 1025 bytes, alignment: 1 bytes diff --git a/tests/ui/coroutine/discriminant.rs b/tests/ui/coroutine/discriminant.rs index d6879e21825..ca4fcedd7e5 100644 --- a/tests/ui/coroutine/discriminant.rs +++ b/tests/ui/coroutine/discriminant.rs @@ -124,12 +124,14 @@ fn main() { }; assert_eq!(size_of_val(&gen_u8_tiny_niche()), 1); - assert_eq!(size_of_val(&Some(gen_u8_tiny_niche())), 1); // uses niche + // FIXME(#63818): niches in coroutines are disabled. + // assert_eq!(size_of_val(&Some(gen_u8_tiny_niche())), 1); // uses niche assert_eq!(size_of_val(&Some(Some(gen_u8_tiny_niche()))), 2); // cannot use niche anymore assert_eq!(size_of_val(&gen_u8_full()), 1); assert_eq!(size_of_val(&Some(gen_u8_full())), 2); // cannot use niche assert_eq!(size_of_val(&gen_u16()), 2); - assert_eq!(size_of_val(&Some(gen_u16())), 2); // uses niche + // FIXME(#63818): niches in coroutines are disabled. + // assert_eq!(size_of_val(&Some(gen_u16())), 2); // uses niche cycle(gen_u8_tiny_niche(), 254); cycle(gen_u8_full(), 255); diff --git a/tests/ui/coroutine/niche-in-coroutine.rs b/tests/ui/coroutine/niche-in-coroutine.rs index 117ee9e6f03..f268ef09f89 100644 --- a/tests/ui/coroutine/niche-in-coroutine.rs +++ b/tests/ui/coroutine/niche-in-coroutine.rs @@ -15,5 +15,6 @@ fn main() { take(x); }; - assert_eq!(size_of_val(&gen1), size_of_val(&Some(gen1))); + // FIXME(#63818): niches in coroutines are disabled. Should be `assert_eq`. + assert_ne!(size_of_val(&gen1), size_of_val(&Some(gen1))); } |