Made from_waker, waker, from_raw const

library/alloc/src/lib.rs

@@ -109,6 +109,7 @@
 #![feature(core_intrinsics)]
 #![feature(const_eval_select)]
 #![feature(const_pin)]
+#![feature(const_waker)]
 #![feature(cstr_from_bytes_until_nul)]
 #![feature(dispatch_from_dyn)]
 #![cfg_attr(not(bootstrap), feature(error_generic_member_access))]

library/core/src/lib.rs

@@ -145,6 +145,7 @@
 #![feature(const_default_impls)]
 #![feature(const_unicode_case_lookup)]
 #![feature(const_unsafecell_get_mut)]
+#![feature(const_waker)]
 #![feature(core_panic)]
 #![feature(duration_consts_float)]
 #![feature(maybe_uninit_uninit_array)]

library/core/src/task/wake.rs

@@ -186,17 +186,19 @@ pub struct Context<'a> {
 impl<'a> Context<'a> {
  /// Create a new `Context` from a [`&Waker`](Waker).
  #[stable(feature = "futures_api", since = "1.36.0")]
+ #[rustc_const_unstable(feature = "const_waker", issue = "none")]
  #[must_use]
  #[inline]
- pub fn from_waker(waker: &'a Waker) -> Self {
+ pub const fn from_waker(waker: &'a Waker) -> Self {
  Context { waker, _marker: PhantomData }
  }
 
  /// Returns a reference to the [`Waker`] for the current task.
  #[stable(feature = "futures_api", since = "1.36.0")]
+ #[rustc_const_unstable(feature = "const_waker", issue = "none")]
  #[must_use]
  #[inline]
- pub fn waker(&self) -> &'a Waker {
+ pub const fn waker(&self) -> &'a Waker {
  &self.waker
  }
 }
@@ -311,7 +313,8 @@ impl Waker {
  #[inline]
  #[must_use]
  #[stable(feature = "futures_api", since = "1.36.0")]
- pub unsafe fn from_raw(waker: RawWaker) -> Waker {
+ #[rustc_const_unstable(feature = "const_waker", issue = "none")]
+ pub const unsafe fn from_raw(waker: RawWaker) -> Waker {
  Waker { waker }
  }
 

library/core/tests/lib.rs

@@ -74,6 +74,7 @@
 #![feature(iterator_try_reduce)]
 #![feature(const_mut_refs)]
 #![feature(const_pin)]
+#![feature(const_waker)]
 #![feature(never_type)]
 #![feature(unwrap_infallible)]
 #![feature(pointer_byte_offsets)]

library/core/tests/task.rs

@@ -1,4 +1,4 @@
-use core::task::Poll;
+use core::task::{Context, Poll, RawWaker, RawWakerVTable, Waker};
 
 #[test]
 fn poll_const() {
@@ -12,3 +12,18 @@ fn poll_const() {
  const IS_PENDING: bool = POLL.is_pending();
  assert!(IS_PENDING);
 }
+
+#[test]
+fn waker_const() {
+ const VOID_TABLE: RawWakerVTable = RawWakerVTable::new(|_| VOID_WAKER, |_| {}, |_| {}, |_| {});
+
+ const VOID_WAKER: RawWaker = RawWaker::new(&(), &VOID_TABLE);
+
+ static WAKER: Waker = unsafe { Waker::from_raw(VOID_WAKER) };
+
+ static CONTEXT: Context<'static> = Context::from_waker(&WAKER);
+
+ static WAKER_REF: &'static Waker = CONTEXT.waker();
+
+ WAKER_REF.wake_by_ref();
+}

library/std/src/lib.rs

@@ -315,6 +315,7 @@
 #![feature(strict_provenance)]
 #![feature(maybe_uninit_uninit_array)]
 #![feature(const_maybe_uninit_uninit_array)]
+#![feature(const_waker)]
 //
 // Library features (alloc):
 #![feature(alloc_layout_extra)]