From 9502e2c82d732179ccdd98e1db121b9d8d91b590 Mon Sep 17 00:00:00 2001
From: Jake Vossen <jake@vossen.dev>
Date: Tue, 5 Jan 2021 13:23:46 -0700
Subject: [PATCH 1/3] added sum trait for Duration

---
 src/oldtime.rs | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/src/oldtime.rs b/src/oldtime.rs
index 388b71a47d..8e03657da3 100644
--- a/src/oldtime.rs
+++ b/src/oldtime.rs
@@ -373,6 +373,18 @@ impl Div<i32> for Duration {
     }
 }
 
+impl<'a> std::iter::Sum<&'a Duration> for Duration {
+    fn sum<I: Iterator<Item = &'a Duration>>(iter: I) -> Duration {
+        iter.fold(Duration::zero(), |acc, x| acc + *x)
+    }
+}
+
+impl std::iter::Sum<Duration> for Duration {
+    fn sum<I: Iterator<Item = Duration>>(iter: I) -> Duration {
+        iter.fold(Duration::zero(), |acc, x| acc + x)
+    }
+}
+
 impl fmt::Display for Duration {
     /// Format a duration using the [ISO 8601] format
     ///
@@ -630,6 +642,27 @@ mod tests {
         assert_eq!(Duration::seconds(-4) / -3, Duration::nanoseconds(1_333_333_333));
     }
 
+    #[test]
+    fn test_duration_sum() {
+        let duration_list_1 = [Duration::zero(), Duration::seconds(1)];
+        let sum_1: Duration = duration_list_1.iter().sum();
+        assert_eq!(sum_1, Duration::seconds(1));
+
+        let duration_list_2 =
+            [Duration::zero(), Duration::seconds(1), Duration::seconds(6), Duration::seconds(10)];
+        let sum_2: Duration = duration_list_2.iter().sum();
+        assert_eq!(sum_2, Duration::seconds(17));
+
+        let duration_vec = vec![
+            Duration::zero(),
+            Duration::seconds(1),
+            Duration::seconds(6),
+            Duration::seconds(10),
+        ];
+        let sum_3: Duration = duration_vec.into_iter().sum();
+        assert_eq!(sum_3, Duration::seconds(17));
+    }
+
     #[test]
     fn test_duration_fmt() {
         assert_eq!(Duration::zero().to_string(), "PT0S");

From 87e325418e1278d66ec5aec5476edd6b2b43bed4 Mon Sep 17 00:00:00 2001
From: Jake Vossen <jake@vossen.dev>
Date: Tue, 5 Jan 2021 13:27:05 -0700
Subject: [PATCH 2/3] added to changelog and authors

---
 AUTHORS.txt  | 1 +
 CHANGELOG.md | 1 +
 2 files changed, 2 insertions(+)

diff --git a/AUTHORS.txt b/AUTHORS.txt
index 9501a9d059..5a07a48908 100644
--- a/AUTHORS.txt
+++ b/AUTHORS.txt
@@ -22,6 +22,7 @@ Eunchong Yu <kroisse@gmail.com>
 Frans Skarman <frans.skarman@gmail.com>
 Huon Wilson <dbau.pp+github@gmail.com>
 Igor Gnatenko <ignatenko@redhat.com>
+Jake Vossen <jake@vossen.dev>
 Jim Turner <jturner314@gmail.com>
 Jisoo Park <xxxyel@gmail.com>
 Joe Wilm <joe@jwilm.com>
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 16a9063b60..e922595d5f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,6 +17,7 @@ Versions with only mechanical changes will be omitted from the following list.
 * Add support for microseconds timestamps serde serialization/deserialization (#304)
 * Fix `DurationRound` is not TZ aware (#495)
 * Implement `DurationRound` for `NaiveDateTime`
+* Implement `std::iter::Sum` for `Duration`
 
 ## 0.4.19
 

From d807ae5068dd649d3118430e1420f1160c1c1159 Mon Sep 17 00:00:00 2001
From: Jake Vossen <jake@vossen.dev>
Date: Fri, 22 Jan 2021 10:19:57 -0700
Subject: [PATCH 3/3] Sum only implemented when std is enabled

---
 src/oldtime.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/oldtime.rs b/src/oldtime.rs
index 8e03657da3..0a28817795 100644
--- a/src/oldtime.rs
+++ b/src/oldtime.rs
@@ -373,12 +373,14 @@ impl Div<i32> for Duration {
     }
 }
 
+#[cfg(any(feature = "std", test))]
 impl<'a> std::iter::Sum<&'a Duration> for Duration {
     fn sum<I: Iterator<Item = &'a Duration>>(iter: I) -> Duration {
         iter.fold(Duration::zero(), |acc, x| acc + *x)
     }
 }
 
+#[cfg(any(feature = "std", test))]
 impl std::iter::Sum<Duration> for Duration {
     fn sum<I: Iterator<Item = Duration>>(iter: I) -> Duration {
         iter.fold(Duration::zero(), |acc, x| acc + x)