diff --git a/library/core/src/task/wake.rs b/library/core/src/task/wake.rs
index 1b43c46bda5..fe39f6c0b56 100644
--- a/library/core/src/task/wake.rs
+++ b/library/core/src/task/wake.rs
@@ -2,6 +2,7 @@
use crate::mem::transmute;
+use crate::any::Any;
use crate::fmt;
use crate::marker::PhantomData;
use crate::ptr;
@@ -220,6 +221,12 @@ impl RawWakerVTable {
}
}
+#[derive(Debug)]
+enum ExtData<'a> {
+ Some(&'a mut dyn Any),
+ None(()),
+}
+
/// The context of an asynchronous task.
///
/// Currently, `Context` only serves to provide access to a [`&Waker`](Waker)
@@ -229,6 +236,7 @@ impl RawWakerVTable {
pub struct Context<'a> {
waker: &'a Waker,
local_waker: &'a LocalWaker,
+ ext: ExtData<'a>,
// Ensure we future-proof against variance changes by forcing
// the lifetime to be invariant (argument-position lifetimes
// are contravariant while return-position lifetimes are
@@ -257,6 +265,7 @@ impl<'a> Context<'a> {
pub const fn waker(&self) -> &'a Waker {
&self.waker
}
+
/// Returns a reference to the [`LocalWaker`] for the current task.
#[inline]
#[unstable(feature = "local_waker", issue = "118959")]
@@ -264,6 +273,17 @@ impl<'a> Context<'a> {
pub const fn local_waker(&self) -> &'a LocalWaker {
&self.local_waker
}
+
+ /// Returns a reference to the extension data for the current task.
+ #[inline]
+ #[unstable(feature = "context_ext", issue = "123392")]
+ #[rustc_const_unstable(feature = "const_waker", issue = "102012")]
+ pub const fn ext(&mut self) -> &mut dyn Any {
+ match &mut self.ext {
+ ExtData::Some(data) => *data,
+ ExtData::None(unit) => unit,
+ }
+ }
}
#[stable(feature = "futures_api", since = "1.36.0")]
@@ -300,6 +320,7 @@ impl fmt::Debug for Context<'_> {
pub struct ContextBuilder<'a> {
waker: &'a Waker,
local_waker: &'a LocalWaker,
+ ext: ExtData<'a>,
// Ensure we future-proof against variance changes by forcing
// the lifetime to be invariant (argument-position lifetimes
// are contravariant while return-position lifetimes are
@@ -318,7 +339,39 @@ impl<'a> ContextBuilder<'a> {
pub const fn from_waker(waker: &'a Waker) -> Self {
// SAFETY: LocalWaker is just Waker without thread safety
let local_waker = unsafe { transmute(waker) };
- Self { waker: waker, local_waker, _marker: PhantomData, _marker2: PhantomData }
+ Self {
+ waker: waker,
+ local_waker,
+ ext: ExtData::None(()),
+ _marker: PhantomData,
+ _marker2: PhantomData,
+ }
+ }
+
+ /// Create a ContextBuilder from an existing Context.
+ #[inline]
+ #[rustc_const_unstable(feature = "const_waker", issue = "102012")]
+ #[unstable(feature = "context_ext", issue = "123392")]
+ pub const fn from(cx: &'a mut Context<'_>) -> Self {
+ let ext = match &mut cx.ext {
+ ExtData::Some(ext) => ExtData::Some(*ext),
+ ExtData::None(()) => ExtData::None(()),
+ };
+ Self {
+ waker: cx.waker,
+ local_waker: cx.local_waker,
+ ext,
+ _marker: PhantomData,
+ _marker2: PhantomData,
+ }
+ }
+
+ /// This method is used to set the value for the waker on `Context`.
+ #[inline]
+ #[unstable(feature = "context_ext", issue = "123392")]
+ #[rustc_const_unstable(feature = "const_waker", issue = "102012")]
+ pub const fn waker(self, waker: &'a Waker) -> Self {
+ Self { waker, ..self }
}
/// This method is used to set the value for the local waker on `Context`.
@@ -329,13 +382,21 @@ impl<'a> ContextBuilder<'a> {
Self { local_waker, ..self }
}
+ /// This method is used to set the value for the extension data on `Context`.
+ #[inline]
+ #[unstable(feature = "context_ext", issue = "123392")]
+ #[rustc_const_unstable(feature = "const_waker", issue = "102012")]
+ pub const fn ext(self, data: &'a mut dyn Any) -> Self {
+ Self { ext: ExtData::Some(data), ..self }
+ }
+
/// Builds the `Context`.
#[inline]
#[unstable(feature = "local_waker", issue = "118959")]
#[rustc_const_unstable(feature = "const_waker", issue = "102012")]
pub const fn build(self) -> Context<'a> {
- let ContextBuilder { waker, local_waker, _marker, _marker2 } = self;
- Context { waker, local_waker, _marker, _marker2 }
+ let ContextBuilder { waker, local_waker, ext, _marker, _marker2 } = self;
+ Context { waker, local_waker, ext, _marker, _marker2 }
}
}
diff --git a/tests/ui/async-await/async-is-unwindsafe.rs b/tests/ui/async-await/async-is-unwindsafe.rs
index 53009b6e741..d0202f72f00 100644
--- a/tests/ui/async-await/async-is-unwindsafe.rs
+++ b/tests/ui/async-await/async-is-unwindsafe.rs
@@ -11,6 +11,7 @@ fn main() {
is_unwindsafe(async {
//~^ ERROR the type `&mut Context<'_>` may not be safely transferred across an unwind boundary
+ //~| ERROR the type `&mut (dyn Any + 'static)` may not be safely transferred across an unwind boundary
use std::ptr::null;
use std::task::{Context, RawWaker, RawWakerVTable, Waker};
let waker = unsafe {
diff --git a/tests/ui/async-await/async-is-unwindsafe.stderr b/tests/ui/async-await/async-is-unwindsafe.stderr
index 5d87fc74768..6bb06df9f39 100644
--- a/tests/ui/async-await/async-is-unwindsafe.stderr
+++ b/tests/ui/async-await/async-is-unwindsafe.stderr
@@ -6,19 +6,18 @@ LL | is_unwindsafe(async {
| |_____|
| ||
LL | ||
+LL | ||
LL | || use std::ptr::null;
-LL | || use std::task::{Context, RawWaker, RawWakerVTable, Waker};
... ||
LL | || drop(cx_ref);
LL | || });
| ||_____-^ `&mut Context<'_>` may not be safely transferred across an unwind boundary
| |_____|
- | within this `{async block@$DIR/async-is-unwindsafe.rs:12:19: 29:6}`
+ | within this `{async block@$DIR/async-is-unwindsafe.rs:12:19: 30:6}`
|
- = help: within `{async block@$DIR/async-is-unwindsafe.rs:12:19: 29:6}`, the trait `UnwindSafe` is not implemented for `&mut Context<'_>`, which is required by `{async block@$DIR/async-is-unwindsafe.rs:12:19: 29:6}: UnwindSafe`
- = note: `UnwindSafe` is implemented for `&Context<'_>`, but not for `&mut Context<'_>`
+ = help: within `{async block@$DIR/async-is-unwindsafe.rs:12:19: 30:6}`, the trait `UnwindSafe` is not implemented for `&mut Context<'_>`, which is required by `{async block@$DIR/async-is-unwindsafe.rs:12:19: 30:6}: UnwindSafe`
note: future does not implement `UnwindSafe` as this value is used across an await
- --> $DIR/async-is-unwindsafe.rs:25:18
+ --> $DIR/async-is-unwindsafe.rs:26:18
|
LL | let cx_ref = &mut cx;
| ------ has type `&mut Context<'_>` which does not implement `UnwindSafe`
@@ -31,6 +30,38 @@ note: required by a bound in `is_unwindsafe`
LL | fn is_unwindsafe(_: impl std::panic::UnwindSafe) {}
| ^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_unwindsafe`
-error: aborting due to 1 previous error
+error[E0277]: the type `&mut (dyn Any + 'static)` may not be safely transferred across an unwind boundary
+ --> $DIR/async-is-unwindsafe.rs:12:5
+ |
+LL | is_unwindsafe(async {
+ | _____^_____________-
+ | |_____|
+ | ||
+LL | ||
+LL | ||
+LL | || use std::ptr::null;
+... ||
+LL | || drop(cx_ref);
+LL | || });
+ | ||_____-^ `&mut (dyn Any + 'static)` may not be safely transferred across an unwind boundary
+ | |_____|
+ | within this `{async block@$DIR/async-is-unwindsafe.rs:12:19: 30:6}`
+ |
+ = help: within `{async block@$DIR/async-is-unwindsafe.rs:12:19: 30:6}`, the trait `UnwindSafe` is not implemented for `&mut (dyn Any + 'static)`, which is required by `{async block@$DIR/async-is-unwindsafe.rs:12:19: 30:6}: UnwindSafe`
+note: future does not implement `UnwindSafe` as this value is used across an await
+ --> $DIR/async-is-unwindsafe.rs:26:18
+ |
+LL | let mut cx = Context::from_waker(&waker);
+ | ------ has type `Context<'_>` which does not implement `UnwindSafe`
+...
+LL | async {}.await; // this needs an inner await point
+ | ^^^^^ await occurs here, with `mut cx` maybe used later
+note: required by a bound in `is_unwindsafe`
+ --> $DIR/async-is-unwindsafe.rs:3:26
+ |
+LL | fn is_unwindsafe(_: impl std::panic::UnwindSafe) {}
+ | ^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_unwindsafe`
+
+error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0277`.