From 8c534771e29f478488e782acdb0af9149984809d Mon Sep 17 00:00:00 2001
From: Paul Dicker <pitdicker@gmail.com>
Date: Fri, 19 May 2023 14:52:26 +0200
Subject: [PATCH] Use `checked_(add|sub)_offset` in `Add` and `Sub` impls of
 `DateTime`

---
 src/datetime/mod.rs | 20 ++++++--------------
 1 file changed, 6 insertions(+), 14 deletions(-)

diff --git a/src/datetime/mod.rs b/src/datetime/mod.rs
index 03ef4fa82f..7426f03d00 100644
--- a/src/datetime/mod.rs
+++ b/src/datetime/mod.rs
@@ -1247,22 +1247,13 @@ impl<Tz: TimeZone> AddAssign<Duration> for DateTime<Tz> {
     }
 }
 
-fn add_with_leapsecond<T>(lhs: &T, rhs: i32) -> T
-where
-    T: Timelike + Add<OldDuration, Output = T>,
-{
-    // extract and temporarily remove the fractional part and later recover it
-    let nanos = lhs.nanosecond();
-    let lhs = lhs.with_nanosecond(0).unwrap();
-    (lhs + OldDuration::seconds(i64::from(rhs))).with_nanosecond(nanos).unwrap()
-}
-
 impl<Tz: TimeZone> Add<FixedOffset> for DateTime<Tz> {
     type Output = DateTime<Tz>;
 
     #[inline]
-    fn add(self, rhs: FixedOffset) -> DateTime<Tz> {
-        add_with_leapsecond(&self, rhs.local_minus_utc())
+    fn add(mut self, rhs: FixedOffset) -> DateTime<Tz> {
+        self.datetime = self.naive_utc().checked_add_offset(rhs).unwrap();
+        self
     }
 }
 
@@ -1317,8 +1308,9 @@ impl<Tz: TimeZone> Sub<FixedOffset> for DateTime<Tz> {
     type Output = DateTime<Tz>;
 
     #[inline]
-    fn sub(self, rhs: FixedOffset) -> DateTime<Tz> {
-        add_with_leapsecond(&self, -rhs.local_minus_utc())
+    fn sub(mut self, rhs: FixedOffset) -> DateTime<Tz> {
+        self.datetime = self.naive_utc().checked_sub_offset(rhs).unwrap();
+        self
     }
 }