From d1e23b8af8615a0b0bbb22f11674b977d2ecdd54 Mon Sep 17 00:00:00 2001
From: Mara Bos <m-ou.se@m-ou.se>
Date: Sun, 11 Apr 2021 11:24:17 +0200
Subject: [PATCH 1/2] Stabilize duration_zero.

---
 library/core/src/time.rs  | 7 ++-----
 library/core/tests/lib.rs | 1 -
 library/std/src/lib.rs    | 1 -
 3 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/library/core/src/time.rs b/library/core/src/time.rs
index 2219353b055ad..f6d480ae54b38 100644
--- a/library/core/src/time.rs
+++ b/library/core/src/time.rs
@@ -124,14 +124,13 @@ impl Duration {
     /// # Examples
     ///
     /// ```
-    /// #![feature(duration_zero)]
     /// use std::time::Duration;
     ///
     /// let duration = Duration::ZERO;
     /// assert!(duration.is_zero());
     /// assert_eq!(duration.as_nanos(), 0);
     /// ```
-    #[unstable(feature = "duration_zero", issue = "73544")]
+    #[stable(feature = "duration_zero", since = "1.53.0")]
     pub const ZERO: Duration = Duration::from_nanos(0);
 
     /// The maximum duration.
@@ -269,7 +268,6 @@ impl Duration {
     /// # Examples
     ///
     /// ```
-    /// #![feature(duration_zero)]
     /// use std::time::Duration;
     ///
     /// assert!(Duration::ZERO.is_zero());
@@ -281,7 +279,7 @@ impl Duration {
     /// assert!(!Duration::from_nanos(1).is_zero());
     /// assert!(!Duration::from_secs(1).is_zero());
     /// ```
-    #[unstable(feature = "duration_zero", issue = "73544")]
+    #[stable(feature = "duration_zero", since = "1.53.0")]
     #[inline]
     pub const fn is_zero(&self) -> bool {
         self.secs == 0 && self.nanos == 0
@@ -536,7 +534,6 @@ impl Duration {
     /// # Examples
     ///
     /// ```
-    /// #![feature(duration_zero)]
     /// use std::time::Duration;
     ///
     /// assert_eq!(Duration::new(0, 1).saturating_sub(Duration::new(0, 0)), Duration::new(0, 1));
diff --git a/library/core/tests/lib.rs b/library/core/tests/lib.rs
index 3e5e5f32609db..4b52cc5aec155 100644
--- a/library/core/tests/lib.rs
+++ b/library/core/tests/lib.rs
@@ -24,7 +24,6 @@
 #![feature(div_duration)]
 #![feature(duration_consts_2)]
 #![feature(duration_constants)]
-#![feature(duration_zero)]
 #![feature(exact_size_is_empty)]
 #![feature(extern_types)]
 #![feature(flt2dec)]
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 91695ced6a962..d532bc076e0a8 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -261,7 +261,6 @@
 #![cfg_attr(not(bootstrap), feature(doc_notable_trait))]
 #![feature(dropck_eyepatch)]
 #![feature(duration_constants)]
-#![feature(duration_zero)]
 #![feature(edition_panic)]
 #![feature(exact_size_is_empty)]
 #![feature(exhaustive_patterns)]

From b44ae964e2086b280a250dea62abad29164eea58 Mon Sep 17 00:00:00 2001
From: Mara Bos <m-ou.se@m-ou.se>
Date: Sun, 11 Apr 2021 11:36:35 +0200
Subject: [PATCH 2/2] Mark Duration::is_zero as rustc_const_stable.

---
 library/core/src/time.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/library/core/src/time.rs b/library/core/src/time.rs
index f6d480ae54b38..fa6a6c2cccc01 100644
--- a/library/core/src/time.rs
+++ b/library/core/src/time.rs
@@ -280,6 +280,7 @@ impl Duration {
     /// assert!(!Duration::from_secs(1).is_zero());
     /// ```
     #[stable(feature = "duration_zero", since = "1.53.0")]
+    #[rustc_const_stable(feature = "duration_zero", since = "1.53.0")]
     #[inline]
     pub const fn is_zero(&self) -> bool {
         self.secs == 0 && self.nanos == 0