Auto merge of rust-lang#133089 - eholk:stabilize-noop-waker, r=dtolnay

Stabilize noop_waker

Tracking Issue: rust-lang#98286

This is a handy feature that's been used widely in tests and example async code and it'd be nice to make it available to users.

cc `@rust-lang/wg-async`

Author: bors

library/alloc/src/task.rs

@@ -199,7 +199,6 @@ fn raw_waker<W: Wake + Send + Sync + 'static>(waker: Arc<W>) -> RawWaker {
 ///
 /// ```rust
 /// #![feature(local_waker)]
-/// #![feature(noop_waker)]
 /// use std::task::{LocalWake, ContextBuilder, LocalWaker, Waker};
 /// use std::future::Future;
 /// use std::pin::Pin;

library/core/src/task/wake.rs

@@ -60,7 +60,8 @@ impl RawWaker {
         RawWaker { data, vtable }
     }
 
-    #[unstable(feature = "noop_waker", issue = "98286")]
+    #[stable(feature = "noop_waker", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "noop_waker", since = "CURRENT_RUSTC_VERSION")]
     const NOOP: RawWaker = {
         const VTABLE: RawWakerVTable = RawWakerVTable::new(
             // Cloning just returns a new no-op raw waker
@@ -283,7 +284,6 @@ impl fmt::Debug for Context<'_> {
 /// # Examples
 /// ```
 /// #![feature(local_waker)]
-/// #![feature(noop_waker)]
 /// use std::task::{ContextBuilder, LocalWaker, Waker, Poll};
 /// use std::future::Future;
 ///
@@ -555,8 +555,6 @@ impl Waker {
     /// # Examples
     ///
     /// ```
-    /// #![feature(noop_waker)]
-    ///
     /// use std::future::Future;
     /// use std::task;
     ///
@@ -567,7 +565,8 @@ impl Waker {
     /// ```
     #[inline]
     #[must_use]
-    #[unstable(feature = "noop_waker", issue = "98286")]
+    #[stable(feature = "noop_waker", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "noop_waker", since = "CURRENT_RUSTC_VERSION")]
     pub const fn noop() -> &'static Waker {
         const WAKER: &Waker = &Waker { waker: RawWaker::NOOP };
         WAKER
@@ -850,8 +849,6 @@ impl LocalWaker {
     ///
     /// ```
     /// #![feature(local_waker)]
-    /// #![feature(noop_waker)]
-    ///
     /// use std::future::Future;
     /// use std::task::{ContextBuilder, LocalWaker, Waker, Poll};
     ///
@@ -864,7 +861,7 @@ impl LocalWaker {
     /// ```
     #[inline]
     #[must_use]
-    #[unstable(feature = "noop_waker", issue = "98286")]
+    #[unstable(feature = "local_waker", issue = "118959")]
     pub const fn noop() -> &'static LocalWaker {
         const WAKER: &LocalWaker = &LocalWaker { waker: RawWaker::NOOP };
         WAKER

library/core/tests/lib.rs

@@ -61,7 +61,6 @@
 #![feature(maybe_uninit_write_slice)]
 #![feature(min_specialization)]
 #![feature(never_type)]
-#![feature(noop_waker)]
 #![feature(num_midpoint_signed)]
 #![feature(numfmt)]
 #![feature(pattern)]

src/tools/miri/tests/pass/async-closure-captures.rs

@@ -1,6 +1,6 @@
 // Same as rustc's `tests/ui/async-await/async-closures/captures.rs`, keep in sync
 
-#![feature(async_closure, noop_waker, async_trait_bounds)]
+#![feature(async_closure, async_trait_bounds)]
 
 use std::future::Future;
 use std::pin::pin;

src/tools/miri/tests/pass/async-closure-drop.rs

@@ -1,4 +1,4 @@
-#![feature(async_closure, noop_waker, async_trait_bounds)]
+#![feature(async_closure, async_trait_bounds)]
 
 use std::future::Future;
 use std::pin::pin;

src/tools/miri/tests/pass/async-closure.rs

@@ -1,4 +1,4 @@
-#![feature(async_closure, noop_waker, async_fn_traits)]
+#![feature(async_closure, async_fn_traits)]
 #![allow(unused)]
 
 use std::future::Future;

src/tools/miri/tests/pass/async-drop.rs

@@ -6,7 +6,7 @@
 // please consider modifying rustc's async drop test at
 // `tests/ui/async-await/async-drop.rs`.
 
-#![feature(async_drop, impl_trait_in_assoc_type, noop_waker, async_closure)]
+#![feature(async_drop, impl_trait_in_assoc_type, async_closure)]
 #![allow(incomplete_features, dead_code)]
 
 // FIXME(zetanumbers): consider AsyncDestruct::async_drop cleanup tests

src/tools/miri/tests/pass/async-fn.rs

@@ -1,5 +1,4 @@
 #![feature(never_type)]
-#![feature(noop_waker)]
 
 use std::future::Future;
 

src/tools/miri/tests/pass/dyn-star.rs

@@ -1,7 +1,6 @@
 #![feature(dyn_star)]
 #![allow(incomplete_features)]
 #![feature(custom_inner_attributes)]
-#![feature(noop_waker)]
 // rustfmt destroys `dyn* Trait` syntax
 #![rustfmt::skip]
 

src/tools/miri/tests/pass/future-self-referential.rs

@@ -1,6 +1,5 @@
 //@revisions: stack tree
 //@[tree]compile-flags: -Zmiri-tree-borrows
-#![feature(noop_waker)]
 
 use std::future::*;
 use std::marker::PhantomPinned;

src/tools/miri/tests/pass/issues/issue-miri-2068.rs

@@ -1,5 +1,3 @@
-#![feature(noop_waker)]
-
 use std::future::Future;
 use std::pin::Pin;
 use std::task::{Context, Poll, Waker};

src/tools/miri/tests/pass/move-data-across-await-point.rs

@@ -1,4 +1,3 @@
-#![feature(noop_waker)]
 use std::future::Future;
 use std::ptr;