Fix panic in DateTime::checked_add_days

Incidentally, add TimeDelta::try_* builders so that it's possible to
build them without risking a panic.

Author: Ekleog

src/naive/date.rs

@@ -644,6 +644,10 @@ impl NaiveDate {
     ///     NaiveDate::from_ymd_opt(2022, 7, 31).unwrap().checked_add_days(Days::new(2)),
     ///     Some(NaiveDate::from_ymd_opt(2022, 8, 2).unwrap())
     /// );
+    /// assert_eq!(
+    ///     NaiveDate::from_ymd_opt(2022, 7, 31).unwrap().checked_add_days(Days::new(1000000000000)),
+    ///     None
+    /// );
     /// ```
     pub fn checked_add_days(self, days: Days) -> Option<Self> {
         if days.0 == 0 {
@@ -673,7 +677,7 @@ impl NaiveDate {
     }
 
     fn diff_days(self, days: i64) -> Option<Self> {
-        self.checked_add_signed(TimeDelta::days(days))
+        self.checked_add_signed(TimeDelta::try_days(days)?)
     }
 
     /// Makes a new `NaiveDateTime` from the current date and given `NaiveTime`.

src/time_delta.rs

@@ -75,47 +75,83 @@ impl TimeDelta {
     /// Panics when the duration is out of bounds.
     #[inline]
     pub fn weeks(weeks: i64) -> TimeDelta {
-        let secs = weeks.checked_mul(SECS_PER_WEEK).expect("Duration::weeks out of bounds");
-        TimeDelta::seconds(secs)
+        TimeDelta::try_weeks(weeks).expect("Duration::weeks out of bounds")
+    }
+
+    /// Makes a new `Duration` with given number of weeks.
+    /// Equivalent to `Duration::seconds(weeks * 7 * 24 * 60 * 60)` with overflow checks.
+    /// Returns None when the duration is out of bounds.
+    #[inline]
+    pub fn try_weeks(weeks: i64) -> Option<TimeDelta> {
+        weeks.checked_mul(SECS_PER_WEEK).and_then(TimeDelta::try_seconds)
     }
 
     /// Makes a new `Duration` with given number of days.
     /// Equivalent to `Duration::seconds(days * 24 * 60 * 60)` with overflow checks.
     /// Panics when the duration is out of bounds.
     #[inline]
     pub fn days(days: i64) -> TimeDelta {
-        let secs = days.checked_mul(SECS_PER_DAY).expect("Duration::days out of bounds");
-        TimeDelta::seconds(secs)
+        TimeDelta::try_days(days).expect("Duration::days out of bounds")
+    }
+
+    /// Makes a new `Duration` with given number of days.
+    /// Equivalent to `Duration::seconds(days * 24 * 60 * 60)` with overflow checks.
+    /// Returns None when the duration is out of bounds.
+    #[inline]
+    pub fn try_days(days: i64) -> Option<TimeDelta> {
+        days.checked_mul(SECS_PER_DAY).and_then(TimeDelta::try_seconds)
     }
 
     /// Makes a new `Duration` with given number of hours.
     /// Equivalent to `Duration::seconds(hours * 60 * 60)` with overflow checks.
     /// Panics when the duration is out of bounds.
     #[inline]
     pub fn hours(hours: i64) -> TimeDelta {
-        let secs = hours.checked_mul(SECS_PER_HOUR).expect("Duration::hours ouf of bounds");
-        TimeDelta::seconds(secs)
+        TimeDelta::try_hours(hours).expect("Duration::hours ouf of bounds")
+    }
+
+    /// Makes a new `Duration` with given number of hours.
+    /// Equivalent to `Duration::seconds(hours * 60 * 60)` with overflow checks.
+    /// Returns None when the duration is out of bounds.
+    #[inline]
+    pub fn try_hours(hours: i64) -> Option<TimeDelta> {
+        hours.checked_mul(SECS_PER_HOUR).and_then(TimeDelta::try_seconds)
     }
 
     /// Makes a new `Duration` with given number of minutes.
     /// Equivalent to `Duration::seconds(minutes * 60)` with overflow checks.
     /// Panics when the duration is out of bounds.
     #[inline]
     pub fn minutes(minutes: i64) -> TimeDelta {
-        let secs = minutes.checked_mul(SECS_PER_MINUTE).expect("Duration::minutes out of bounds");
-        TimeDelta::seconds(secs)
+        TimeDelta::try_minutes(minutes).expect("Duration::minutes out of bounds")
+    }
+
+    /// Makes a new `Duration` with given number of minutes.
+    /// Equivalent to `Duration::seconds(minutes * 60)` with overflow checks.
+    /// Returns None when the duration is out of bounds.
+    #[inline]
+    pub fn try_minutes(minutes: i64) -> Option<TimeDelta> {
+        minutes.checked_mul(SECS_PER_MINUTE).and_then(TimeDelta::try_seconds)
     }
 
     /// Makes a new `Duration` with given number of seconds.
     /// Panics when the duration is more than `i64::MAX` seconds
     /// or less than `i64::MIN` seconds.
     #[inline]
     pub fn seconds(seconds: i64) -> TimeDelta {
+        TimeDelta::try_seconds(seconds).expect("Duration::seconds out of bounds")
+    }
+
+    /// Makes a new `Duration` with given number of seconds.
+    /// Returns None when the duration is more than `i64::MAX` milliseconds
+    /// or less than `i64::MIN` milliseconds.
+    #[inline]
+    pub fn try_seconds(seconds: i64) -> Option<TimeDelta> {
         let d = TimeDelta { secs: seconds, nanos: 0 };
         if d < MIN || d > MAX {
-            panic!("Duration::seconds out of bounds");
+            return None;
         }
-        d
+        Some(d)
     }
 
     /// Makes a new `Duration` with given number of milliseconds.