Stabilize `Poll::is_ready` and `is_pending` as const

Insta-stabilize the methods `is_ready` and `is_pending` of `Poll`.

Possible because of the recent stabilization of const control flow.

Also adds a test for these methods in a const context.

2 files changed, 17 insertions, 2 deletions

diff --git a/library/core/src/task/poll.rs b/library/core/src/task/poll.rs
index 9383e7c45fa..a789e4e2593 100644
--- a/library/core/src/task/poll.rs
+++ b/library/core/src/task/poll.rs
@@ -39,15 +39,17 @@ impl<T> Poll<T> {
 
     /// Returns `true` if this is `Poll::Ready`
     #[inline]
+    #[rustc_const_stable(feature = "const_poll", since = "1.48.0")]
     #[stable(feature = "futures_api", since = "1.36.0")]
-    pub fn is_ready(&self) -> bool {
+    pub const fn is_ready(&self) -> bool {
         matches!(*self, Poll::Ready(_))
     }
 
     /// Returns `true` if this is `Poll::Pending`
     #[inline]
+    #[rustc_const_stable(feature = "const_poll", since = "1.48.0")]
     #[stable(feature = "futures_api", since = "1.36.0")]
-    pub fn is_pending(&self) -> bool {
+    pub const fn is_pending(&self) -> bool {
         !self.is_ready()
     }
 }
diff --git a/src/test/ui/consts/std/poll.rs b/src/test/ui/consts/std/poll.rs
new file mode 100644
index 00000000000..28f2ace6715
--- /dev/null
+++ b/src/test/ui/consts/std/poll.rs
@@ -0,0 +1,13 @@
+// run-pass
+
+use std::task::Poll;
+
+fn main() {
+    const POLL : Poll<usize> = Poll::Pending;
+
+    const IS_READY : bool = POLL.is_ready();
+    assert!(!IS_READY);
+
+    const IS_PENDING : bool = POLL.is_pending();
+    assert!(IS_PENDING);
+}