Merging upstream version 1.71.1+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1946 insertions, 0 deletions

diff --git a/vendor/chrono/src/naive/datetime/mod.rs b/vendor/chrono/src/naive/datetime/mod.rs
new file mode 100644
index 000000000..ec0d842c0
--- /dev/null
+++ b/vendor/chrono/src/naive/datetime/mod.rs
@@ -0,0 +1,1946 @@
+// This is a part of Chrono.
+// See README.md and LICENSE.txt for details.
+
+//! ISO 8601 date and time without timezone.
+
+#[cfg(any(feature = "alloc", feature = "std", test))]
+use core::borrow::Borrow;
+use core::convert::TryFrom;
+use core::fmt::Write;
+use core::ops::{Add, AddAssign, Sub, SubAssign};
+use core::{fmt, str};
+
+use num_integer::div_mod_floor;
+use num_traits::ToPrimitive;
+#[cfg(feature = "rkyv")]
+use rkyv::{Archive, Deserialize, Serialize};
+
+#[cfg(any(feature = "alloc", feature = "std", test))]
+use crate::format::DelayedFormat;
+use crate::format::{parse, ParseError, ParseResult, Parsed, StrftimeItems};
+use crate::format::{Fixed, Item, Numeric, Pad};
+use crate::naive::{Days, IsoWeek, NaiveDate, NaiveTime};
+use crate::oldtime::Duration as OldDuration;
+use crate::{DateTime, Datelike, LocalResult, Months, TimeZone, Timelike, Weekday};
+use core::cmp::Ordering;
+
+#[cfg(feature = "rustc-serialize")]
+pub(super) mod rustc_serialize;
+
+/// Tools to help serializing/deserializing `NaiveDateTime`s
+#[cfg(feature = "serde")]
+pub(crate) mod serde;
+
+#[cfg(test)]
+mod tests;
+
+/// The tight upper bound guarantees that a duration with `|Duration| >= 2^MAX_SECS_BITS`
+/// will always overflow the addition with any date and time type.
+///
+/// So why is this needed? `Duration::seconds(rhs)` may overflow, and we don't have
+/// an alternative returning `Option` or `Result`. Thus we need some early bound to avoid
+/// touching that call when we are already sure that it WILL overflow...
+const MAX_SECS_BITS: usize = 44;
+
+/// Number of nanoseconds in a millisecond
+const NANOS_IN_MILLISECOND: u32 = 1_000_000;
+/// Number of nanoseconds in a second
+const NANOS_IN_SECOND: u32 = 1000 * NANOS_IN_MILLISECOND;
+
+/// The minimum possible `NaiveDateTime`.
+#[deprecated(since = "0.4.20", note = "Use NaiveDateTime::MIN instead")]
+pub const MIN_DATETIME: NaiveDateTime = NaiveDateTime::MIN;
+/// The maximum possible `NaiveDateTime`.
+#[deprecated(since = "0.4.20", note = "Use NaiveDateTime::MAX instead")]
+pub const MAX_DATETIME: NaiveDateTime = NaiveDateTime::MAX;
+
+/// ISO 8601 combined date and time without timezone.
+///
+/// # Example
+///
+/// `NaiveDateTime` is commonly created from [`NaiveDate`](./struct.NaiveDate.html).
+///
+/// ```
+/// use chrono::{NaiveDate, NaiveDateTime};
+///
+/// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2016, 7, 8).unwrap().and_hms_opt(9, 10, 11).unwrap();
+/// # let _ = dt;
+/// ```
+///
+/// You can use typical [date-like](../trait.Datelike.html) and
+/// [time-like](../trait.Timelike.html) methods,
+/// provided that relevant traits are in the scope.
+///
+/// ```
+/// # use chrono::{NaiveDate, NaiveDateTime};
+/// # let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2016, 7, 8).unwrap().and_hms_opt(9, 10, 11).unwrap();
+/// use chrono::{Datelike, Timelike, Weekday};
+///
+/// assert_eq!(dt.weekday(), Weekday::Fri);
+/// assert_eq!(dt.num_seconds_from_midnight(), 33011);
+/// ```
+#[derive(PartialEq, Eq, Hash, PartialOrd, Ord, Copy, Clone)]
+#[cfg_attr(feature = "rkyv", derive(Archive, Deserialize, Serialize))]
+#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
+pub struct NaiveDateTime {
+    date: NaiveDate,
+    time: NaiveTime,
+}
+
+/// The unit of a timestamp expressed in fractions of a second.
+/// Currently either milliseconds or microseconds.
+///
+/// This is a private type, used in the implementation of
+/// [NaiveDateTime::from_timestamp_millis] and [NaiveDateTime::from_timestamp_micros].
+#[derive(Clone, Copy, Debug)]
+enum TimestampUnit {
+    Millis,
+    Micros,
+}
+
+impl TimestampUnit {
+    fn per_second(self) -> u32 {
+        match self {
+            TimestampUnit::Millis => 1_000,
+            TimestampUnit::Micros => 1_000_000,
+        }
+    }
+    fn nanos_per(self) -> u32 {
+        match self {
+            TimestampUnit::Millis => 1_000_000,
+            TimestampUnit::Micros => 1_000,
+        }
+    }
+}
+
+impl NaiveDateTime {
+    /// Makes a new `NaiveDateTime` from date and time components.
+    /// Equivalent to [`date.and_time(time)`](./struct.NaiveDate.html#method.and_time)
+    /// and many other helper constructors on `NaiveDate`.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveTime, NaiveDateTime};
+    ///
+    /// let d = NaiveDate::from_ymd_opt(2015, 6, 3).unwrap();
+    /// let t = NaiveTime::from_hms_milli_opt(12, 34, 56, 789).unwrap();
+    ///
+    /// let dt = NaiveDateTime::new(d, t);
+    /// assert_eq!(dt.date(), d);
+    /// assert_eq!(dt.time(), t);
+    /// ```
+    #[inline]
+    pub const fn new(date: NaiveDate, time: NaiveTime) -> NaiveDateTime {
+        NaiveDateTime { date, time }
+    }
+
+    /// Makes a new `NaiveDateTime` corresponding to a UTC date and time,
+    /// from the number of non-leap seconds
+    /// since the midnight UTC on January 1, 1970 (aka "UNIX timestamp")
+    /// and the number of nanoseconds since the last whole non-leap second.
+    ///
+    /// For a non-naive version of this function see
+    /// [`TimeZone::timestamp`](../offset/trait.TimeZone.html#method.timestamp).
+    ///
+    /// The nanosecond part can exceed 1,000,000,000 in order to represent the
+    /// [leap second](./struct.NaiveTime.html#leap-second-handling). (The true "UNIX
+    /// timestamp" cannot represent a leap second unambiguously.)
+    ///
+    /// Panics on the out-of-range number of seconds and/or invalid nanosecond.
+    #[deprecated(since = "0.4.23", note = "use `from_timestamp_opt()` instead")]
+    #[inline]
+    pub fn from_timestamp(secs: i64, nsecs: u32) -> NaiveDateTime {
+        let datetime = NaiveDateTime::from_timestamp_opt(secs, nsecs);
+        datetime.expect("invalid or out-of-range datetime")
+    }
+
+    /// Creates a new [NaiveDateTime] from milliseconds since the UNIX epoch.
+    ///
+    /// The UNIX epoch starts on midnight, January 1, 1970, UTC.
+    ///
+    /// Returns `None` on an out-of-range number of milliseconds.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::NaiveDateTime;
+    /// let timestamp_millis: i64 = 1662921288000; //Sunday, September 11, 2022 6:34:48 PM
+    /// let naive_datetime = NaiveDateTime::from_timestamp_millis(timestamp_millis);
+    /// assert!(naive_datetime.is_some());
+    /// assert_eq!(timestamp_millis, naive_datetime.unwrap().timestamp_millis());
+    ///
+    /// // Negative timestamps (before the UNIX epoch) are supported as well.
+    /// let timestamp_millis: i64 = -2208936075000; //Mon Jan 01 1900 14:38:45 GMT+0000
+    /// let naive_datetime = NaiveDateTime::from_timestamp_millis(timestamp_millis);
+    /// assert!(naive_datetime.is_some());
+    /// assert_eq!(timestamp_millis, naive_datetime.unwrap().timestamp_millis());
+    /// ```
+    #[inline]
+    pub fn from_timestamp_millis(millis: i64) -> Option<NaiveDateTime> {
+        Self::from_timestamp_unit(millis, TimestampUnit::Millis)
+    }
+
+    /// Creates a new [NaiveDateTime] from microseconds since the UNIX epoch.
+    ///
+    /// The UNIX epoch starts on midnight, January 1, 1970, UTC.
+    ///
+    /// Returns `None` on an out-of-range number of microseconds.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::NaiveDateTime;
+    /// let timestamp_micros: i64 = 1662921288000000; //Sunday, September 11, 2022 6:34:48 PM
+    /// let naive_datetime = NaiveDateTime::from_timestamp_micros(timestamp_micros);
+    /// assert!(naive_datetime.is_some());
+    /// assert_eq!(timestamp_micros, naive_datetime.unwrap().timestamp_micros());
+    ///
+    /// // Negative timestamps (before the UNIX epoch) are supported as well.
+    /// let timestamp_micros: i64 = -2208936075000000; //Mon Jan 01 1900 14:38:45 GMT+0000
+    /// let naive_datetime = NaiveDateTime::from_timestamp_micros(timestamp_micros);
+    /// assert!(naive_datetime.is_some());
+    /// assert_eq!(timestamp_micros, naive_datetime.unwrap().timestamp_micros());
+    /// ```
+    #[inline]
+    pub fn from_timestamp_micros(micros: i64) -> Option<NaiveDateTime> {
+        Self::from_timestamp_unit(micros, TimestampUnit::Micros)
+    }
+
+    /// Makes a new `NaiveDateTime` corresponding to a UTC date and time,
+    /// from the number of non-leap seconds
+    /// since the midnight UTC on January 1, 1970 (aka "UNIX timestamp")
+    /// and the number of nanoseconds since the last whole non-leap second.
+    ///
+    /// The nanosecond part can exceed 1,000,000,000
+    /// in order to represent the [leap second](./struct.NaiveTime.html#leap-second-handling).
+    /// (The true "UNIX timestamp" cannot represent a leap second unambiguously.)
+    ///
+    /// Returns `None` on the out-of-range number of seconds (more than 262 000 years away
+    /// from common era) and/or invalid nanosecond (2 seconds or more).
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDateTime, NaiveDate};
+    /// use std::i64;
+    ///
+    /// let from_timestamp_opt = NaiveDateTime::from_timestamp_opt;
+    ///
+    /// assert!(from_timestamp_opt(0, 0).is_some());
+    /// assert!(from_timestamp_opt(0, 999_999_999).is_some());
+    /// assert!(from_timestamp_opt(0, 1_500_000_000).is_some()); // leap second
+    /// assert!(from_timestamp_opt(0, 2_000_000_000).is_none());
+    /// assert!(from_timestamp_opt(i64::MAX, 0).is_none());
+    /// ```
+    #[inline]
+    pub fn from_timestamp_opt(secs: i64, nsecs: u32) -> Option<NaiveDateTime> {
+        let (days, secs) = div_mod_floor(secs, 86_400);
+        let date = days
+            .to_i32()
+            .and_then(|days| days.checked_add(719_163))
+            .and_then(NaiveDate::from_num_days_from_ce_opt);
+        let time = NaiveTime::from_num_seconds_from_midnight_opt(secs as u32, nsecs);
+        match (date, time) {
+            (Some(date), Some(time)) => Some(NaiveDateTime { date, time }),
+            (_, _) => None,
+        }
+    }
+
+    /// Parses a string with the specified format string and returns a new `NaiveDateTime`.
+    /// See the [`format::strftime` module](../format/strftime/index.html)
+    /// on the supported escape sequences.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDateTime, NaiveDate};
+    ///
+    /// let parse_from_str = NaiveDateTime::parse_from_str;
+    ///
+    /// assert_eq!(parse_from_str("2015-09-05 23:56:04", "%Y-%m-%d %H:%M:%S"),
+    ///            Ok(NaiveDate::from_ymd_opt(2015, 9, 5).unwrap().and_hms_opt(23, 56, 4).unwrap()));
+    /// assert_eq!(parse_from_str("5sep2015pm012345.6789", "%d%b%Y%p%I%M%S%.f"),
+    ///            Ok(NaiveDate::from_ymd_opt(2015, 9, 5).unwrap().and_hms_micro_opt(13, 23, 45, 678_900).unwrap()));
+    /// ```
+    ///
+    /// Offset is ignored for the purpose of parsing.
+    ///
+    /// ```
+    /// # use chrono::{NaiveDateTime, NaiveDate};
+    /// # let parse_from_str = NaiveDateTime::parse_from_str;
+    /// assert_eq!(parse_from_str("2014-5-17T12:34:56+09:30", "%Y-%m-%dT%H:%M:%S%z"),
+    ///            Ok(NaiveDate::from_ymd_opt(2014, 5, 17).unwrap().and_hms_opt(12, 34, 56).unwrap()));
+    /// ```
+    ///
+    /// [Leap seconds](./struct.NaiveTime.html#leap-second-handling) are correctly handled by
+    /// treating any time of the form `hh:mm:60` as a leap second.
+    /// (This equally applies to the formatting, so the round trip is possible.)
+    ///
+    /// ```
+    /// # use chrono::{NaiveDateTime, NaiveDate};
+    /// # let parse_from_str = NaiveDateTime::parse_from_str;
+    /// assert_eq!(parse_from_str("2015-07-01 08:59:60.123", "%Y-%m-%d %H:%M:%S%.f"),
+    ///            Ok(NaiveDate::from_ymd_opt(2015, 7, 1).unwrap().and_hms_milli_opt(8, 59, 59, 1_123).unwrap()));
+    /// ```
+    ///
+    /// Missing seconds are assumed to be zero,
+    /// but out-of-bound times or insufficient fields are errors otherwise.
+    ///
+    /// ```
+    /// # use chrono::{NaiveDateTime, NaiveDate};
+    /// # let parse_from_str = NaiveDateTime::parse_from_str;
+    /// assert_eq!(parse_from_str("94/9/4 7:15", "%y/%m/%d %H:%M"),
+    ///            Ok(NaiveDate::from_ymd_opt(1994, 9, 4).unwrap().and_hms_opt(7, 15, 0).unwrap()));
+    ///
+    /// assert!(parse_from_str("04m33s", "%Mm%Ss").is_err());
+    /// assert!(parse_from_str("94/9/4 12", "%y/%m/%d %H").is_err());
+    /// assert!(parse_from_str("94/9/4 17:60", "%y/%m/%d %H:%M").is_err());
+    /// assert!(parse_from_str("94/9/4 24:00:00", "%y/%m/%d %H:%M:%S").is_err());
+    /// ```
+    ///
+    /// All parsed fields should be consistent to each other, otherwise it's an error.
+    ///
+    /// ```
+    /// # use chrono::NaiveDateTime;
+    /// # let parse_from_str = NaiveDateTime::parse_from_str;
+    /// let fmt = "%Y-%m-%d %H:%M:%S = UNIX timestamp %s";
+    /// assert!(parse_from_str("2001-09-09 01:46:39 = UNIX timestamp 999999999", fmt).is_ok());
+    /// assert!(parse_from_str("1970-01-01 00:00:00 = UNIX timestamp 1", fmt).is_err());
+    /// ```
+    ///
+    /// Years before 1 BCE or after 9999 CE, require an initial sign
+    ///
+    ///```
+    /// # use chrono::{NaiveDate, NaiveDateTime};
+    /// # let parse_from_str = NaiveDateTime::parse_from_str;
+    /// let fmt = "%Y-%m-%d %H:%M:%S";
+    /// assert!(parse_from_str("10000-09-09 01:46:39", fmt).is_err());
+    /// assert!(parse_from_str("+10000-09-09 01:46:39", fmt).is_ok());
+    ///```     
+    pub fn parse_from_str(s: &str, fmt: &str) -> ParseResult<NaiveDateTime> {
+        let mut parsed = Parsed::new();
+        parse(&mut parsed, s, StrftimeItems::new(fmt))?;
+        parsed.to_naive_datetime_with_offset(0) // no offset adjustment
+    }
+
+    /// Retrieves a date component.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::NaiveDate;
+    ///
+    /// let dt = NaiveDate::from_ymd_opt(2016, 7, 8).unwrap().and_hms_opt(9, 10, 11).unwrap();
+    /// assert_eq!(dt.date(), NaiveDate::from_ymd_opt(2016, 7, 8).unwrap());
+    /// ```
+    #[inline]
+    pub const fn date(&self) -> NaiveDate {
+        self.date
+    }
+
+    /// Retrieves a time component.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveTime};
+    ///
+    /// let dt = NaiveDate::from_ymd_opt(2016, 7, 8).unwrap().and_hms_opt(9, 10, 11).unwrap();
+    /// assert_eq!(dt.time(), NaiveTime::from_hms_opt(9, 10, 11).unwrap());
+    /// ```
+    #[inline]
+    pub const fn time(&self) -> NaiveTime {
+        self.time
+    }
+
+    /// Returns the number of non-leap seconds since the midnight on January 1, 1970.
+    ///
+    /// Note that this does *not* account for the timezone!
+    /// The true "UNIX timestamp" would count seconds since the midnight *UTC* on the epoch.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::NaiveDate;
+    ///
+    /// let dt = NaiveDate::from_ymd_opt(1970, 1, 1).unwrap().and_hms_milli_opt(0, 0, 1, 980).unwrap();
+    /// assert_eq!(dt.timestamp(), 1);
+    ///
+    /// let dt = NaiveDate::from_ymd_opt(2001, 9, 9).unwrap().and_hms_opt(1, 46, 40).unwrap();
+    /// assert_eq!(dt.timestamp(), 1_000_000_000);
+    ///
+    /// let dt = NaiveDate::from_ymd_opt(1969, 12, 31).unwrap().and_hms_opt(23, 59, 59).unwrap();
+    /// assert_eq!(dt.timestamp(), -1);
+    ///
+    /// let dt = NaiveDate::from_ymd_opt(-1, 1, 1).unwrap().and_hms_opt(0, 0, 0).unwrap();
+    /// assert_eq!(dt.timestamp(), -62198755200);
+    /// ```
+    #[inline]
+    pub fn timestamp(&self) -> i64 {
+        const UNIX_EPOCH_DAY: i64 = 719_163;
+        let gregorian_day = i64::from(self.date.num_days_from_ce());
+        let seconds_from_midnight = i64::from(self.time.num_seconds_from_midnight());
+        (gregorian_day - UNIX_EPOCH_DAY) * 86_400 + seconds_from_midnight
+    }
+
+    /// Returns the number of non-leap *milliseconds* since midnight on January 1, 1970.
+    ///
+    /// Note that this does *not* account for the timezone!
+    /// The true "UNIX timestamp" would count seconds since the midnight *UTC* on the epoch.
+    ///
+    /// Note also that this does reduce the number of years that can be
+    /// represented from ~584 Billion to ~584 Million. (If this is a problem,
+    /// please file an issue to let me know what domain needs millisecond
+    /// precision over billions of years, I'm curious.)
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::NaiveDate;
+    ///
+    /// let dt = NaiveDate::from_ymd_opt(1970, 1, 1).unwrap().and_hms_milli_opt(0, 0, 1, 444).unwrap();
+    /// assert_eq!(dt.timestamp_millis(), 1_444);
+    ///
+    /// let dt = NaiveDate::from_ymd_opt(2001, 9, 9).unwrap().and_hms_milli_opt(1, 46, 40, 555).unwrap();
+    /// assert_eq!(dt.timestamp_millis(), 1_000_000_000_555);
+    ///
+    /// let dt = NaiveDate::from_ymd_opt(1969, 12, 31).unwrap().and_hms_milli_opt(23, 59, 59, 100).unwrap();
+    /// assert_eq!(dt.timestamp_millis(), -900);
+    /// ```
+    #[inline]
+    pub fn timestamp_millis(&self) -> i64 {
+        let as_ms = self.timestamp() * 1000;
+        as_ms + i64::from(self.timestamp_subsec_millis())
+    }
+
+    /// Returns the number of non-leap *microseconds* since midnight on January 1, 1970.
+    ///
+    /// Note that this does *not* account for the timezone!
+    /// The true "UNIX timestamp" would count seconds since the midnight *UTC* on the epoch.
+    ///
+    /// Note also that this does reduce the number of years that can be
+    /// represented from ~584 Billion to ~584 Thousand. (If this is a problem,
+    /// please file an issue to let me know what domain needs microsecond
+    /// precision over millennia, I'm curious.)
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::NaiveDate;
+    ///
+    /// let dt = NaiveDate::from_ymd_opt(1970, 1, 1).unwrap().and_hms_micro_opt(0, 0, 1, 444).unwrap();
+    /// assert_eq!(dt.timestamp_micros(), 1_000_444);
+    ///
+    /// let dt = NaiveDate::from_ymd_opt(2001, 9, 9).unwrap().and_hms_micro_opt(1, 46, 40, 555).unwrap();
+    /// assert_eq!(dt.timestamp_micros(), 1_000_000_000_000_555);
+    /// ```
+    #[inline]
+    pub fn timestamp_micros(&self) -> i64 {
+        let as_us = self.timestamp() * 1_000_000;
+        as_us + i64::from(self.timestamp_subsec_micros())
+    }
+
+    /// Returns the number of non-leap *nanoseconds* since midnight on January 1, 1970.
+    ///
+    /// Note that this does *not* account for the timezone!
+    /// The true "UNIX timestamp" would count seconds since the midnight *UTC* on the epoch.
+    ///
+    /// # Panics
+    ///
+    /// Note also that this does reduce the number of years that can be
+    /// represented from ~584 Billion to ~584 years. The dates that can be
+    /// represented as nanoseconds are between 1677-09-21T00:12:44.0 and
+    /// 2262-04-11T23:47:16.854775804.
+    ///
+    /// (If this is a problem, please file an issue to let me know what domain
+    /// needs nanosecond precision over millennia, I'm curious.)
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime};
+    ///
+    /// let dt = NaiveDate::from_ymd_opt(1970, 1, 1).unwrap().and_hms_nano_opt(0, 0, 1, 444).unwrap();
+    /// assert_eq!(dt.timestamp_nanos(), 1_000_000_444);
+    ///
+    /// let dt = NaiveDate::from_ymd_opt(2001, 9, 9).unwrap().and_hms_nano_opt(1, 46, 40, 555).unwrap();
+    ///
+    /// const A_BILLION: i64 = 1_000_000_000;
+    /// let nanos = dt.timestamp_nanos();
+    /// assert_eq!(nanos, 1_000_000_000_000_000_555);
+    /// assert_eq!(
+    ///     dt,
+    ///     NaiveDateTime::from_timestamp(nanos / A_BILLION, (nanos % A_BILLION) as u32)
+    /// );
+    /// ```
+    #[inline]
+    pub fn timestamp_nanos(&self) -> i64 {
+        let as_ns = self.timestamp() * 1_000_000_000;
+        as_ns + i64::from(self.timestamp_subsec_nanos())
+    }
+
+    /// Returns the number of milliseconds since the last whole non-leap second.
+    ///
+    /// The return value ranges from 0 to 999,
+    /// or for [leap seconds](./struct.NaiveTime.html#leap-second-handling), to 1,999.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::NaiveDate;
+    ///
+    /// let dt = NaiveDate::from_ymd_opt(2016, 7, 8).unwrap().and_hms_nano_opt(9, 10, 11, 123_456_789).unwrap();
+    /// assert_eq!(dt.timestamp_subsec_millis(), 123);
+    ///
+    /// let dt = NaiveDate::from_ymd_opt(2015, 7, 1).unwrap().and_hms_nano_opt(8, 59, 59, 1_234_567_890).unwrap();
+    /// assert_eq!(dt.timestamp_subsec_millis(), 1_234);
+    /// ```
+    #[inline]
+    pub fn timestamp_subsec_millis(&self) -> u32 {
+        self.timestamp_subsec_nanos() / 1_000_000
+    }
+
+    /// Returns the number of microseconds since the last whole non-leap second.
+    ///
+    /// The return value ranges from 0 to 999,999,
+    /// or for [leap seconds](./struct.NaiveTime.html#leap-second-handling), to 1,999,999.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::NaiveDate;
+    ///
+    /// let dt = NaiveDate::from_ymd_opt(2016, 7, 8).unwrap().and_hms_nano_opt(9, 10, 11, 123_456_789).unwrap();
+    /// assert_eq!(dt.timestamp_subsec_micros(), 123_456);
+    ///
+    /// let dt = NaiveDate::from_ymd_opt(2015, 7, 1).unwrap().and_hms_nano_opt(8, 59, 59, 1_234_567_890).unwrap();
+    /// assert_eq!(dt.timestamp_subsec_micros(), 1_234_567);
+    /// ```
+    #[inline]
+    pub fn timestamp_subsec_micros(&self) -> u32 {
+        self.timestamp_subsec_nanos() / 1_000
+    }
+
+    /// Returns the number of nanoseconds since the last whole non-leap second.
+    ///
+    /// The return value ranges from 0 to 999,999,999,
+    /// or for [leap seconds](./struct.NaiveTime.html#leap-second-handling), to 1,999,999,999.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::NaiveDate;
+    ///
+    /// let dt = NaiveDate::from_ymd_opt(2016, 7, 8).unwrap().and_hms_nano_opt(9, 10, 11, 123_456_789).unwrap();
+    /// assert_eq!(dt.timestamp_subsec_nanos(), 123_456_789);
+    ///
+    /// let dt = NaiveDate::from_ymd_opt(2015, 7, 1).unwrap().and_hms_nano_opt(8, 59, 59, 1_234_567_890).unwrap();
+    /// assert_eq!(dt.timestamp_subsec_nanos(), 1_234_567_890);
+    /// ```
+    #[inline]
+    pub fn timestamp_subsec_nanos(&self) -> u32 {
+        self.time.nanosecond()
+    }
+
+    /// Adds given `Duration` to the current date and time.
+    ///
+    /// As a part of Chrono's [leap second handling](./struct.NaiveTime.html#leap-second-handling),
+    /// the addition assumes that **there is no leap second ever**,
+    /// except when the `NaiveDateTime` itself represents a leap second
+    /// in which case the assumption becomes that **there is exactly a single leap second ever**.
+    ///
+    /// Returns `None` when it will result in overflow.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{Duration, NaiveDate};
+    ///
+    /// let from_ymd = NaiveDate::from_ymd;
+    ///
+    /// let d = from_ymd(2016, 7, 8);
+    /// let hms = |h, m, s| d.and_hms_opt(h, m, s).unwrap();
+    /// assert_eq!(hms(3, 5, 7).checked_add_signed(Duration::zero()),
+    ///            Some(hms(3, 5, 7)));
+    /// assert_eq!(hms(3, 5, 7).checked_add_signed(Duration::seconds(1)),
+    ///            Some(hms(3, 5, 8)));
+    /// assert_eq!(hms(3, 5, 7).checked_add_signed(Duration::seconds(-1)),
+    ///            Some(hms(3, 5, 6)));
+    /// assert_eq!(hms(3, 5, 7).checked_add_signed(Duration::seconds(3600 + 60)),
+    ///            Some(hms(4, 6, 7)));
+    /// assert_eq!(hms(3, 5, 7).checked_add_signed(Duration::seconds(86_400)),
+    ///            Some(from_ymd(2016, 7, 9).and_hms_opt(3, 5, 7).unwrap()));
+    ///
+    /// let hmsm = |h, m, s, milli| d.and_hms_milli_opt(h, m, s, milli).unwrap();
+    /// assert_eq!(hmsm(3, 5, 7, 980).checked_add_signed(Duration::milliseconds(450)),
+    ///            Some(hmsm(3, 5, 8, 430)));
+    /// ```
+    ///
+    /// Overflow returns `None`.
+    ///
+    /// ```
+    /// # use chrono::{Duration, NaiveDate};
+    /// # let hms = |h, m, s| NaiveDate::from_ymd_opt(2016, 7, 8).unwrap().and_hms_opt(h, m, s).unwrap();
+    /// assert_eq!(hms(3, 5, 7).checked_add_signed(Duration::days(1_000_000_000)), None);
+    /// ```
+    ///
+    /// Leap seconds are handled,
+    /// but the addition assumes that it is the only leap second happened.
+    ///
+    /// ```
+    /// # use chrono::{Duration, NaiveDate};
+    /// # let from_ymd = NaiveDate::from_ymd;
+    /// # let hmsm = |h, m, s, milli| from_ymd(2016, 7, 8).and_hms_milli_opt(h, m, s, milli).unwrap();
+    /// let leap = hmsm(3, 5, 59, 1_300);
+    /// assert_eq!(leap.checked_add_signed(Duration::zero()),
+    ///            Some(hmsm(3, 5, 59, 1_300)));
+    /// assert_eq!(leap.checked_add_signed(Duration::milliseconds(-500)),
+    ///            Some(hmsm(3, 5, 59, 800)));
+    /// assert_eq!(leap.checked_add_signed(Duration::milliseconds(500)),
+    ///            Some(hmsm(3, 5, 59, 1_800)));
+    /// assert_eq!(leap.checked_add_signed(Duration::milliseconds(800)),
+    ///            Some(hmsm(3, 6, 0, 100)));
+    /// assert_eq!(leap.checked_add_signed(Duration::seconds(10)),
+    ///            Some(hmsm(3, 6, 9, 300)));
+    /// assert_eq!(leap.checked_add_signed(Duration::seconds(-10)),
+    ///            Some(hmsm(3, 5, 50, 300)));
+    /// assert_eq!(leap.checked_add_signed(Duration::days(1)),
+    ///            Some(from_ymd(2016, 7, 9).and_hms_milli_opt(3, 5, 59, 300).unwrap()));
+    /// ```
+    pub fn checked_add_signed(self, rhs: OldDuration) -> Option<NaiveDateTime> {
+        let (time, rhs) = self.time.overflowing_add_signed(rhs);
+
+        // early checking to avoid overflow in OldDuration::seconds
+        if rhs <= (-1 << MAX_SECS_BITS) || rhs >= (1 << MAX_SECS_BITS) {
+            return None;
+        }
+
+        let date = self.date.checked_add_signed(OldDuration::seconds(rhs))?;
+        Some(NaiveDateTime { date, time })
+    }
+
+    /// Adds given `Months` to the current date and time.
+    ///
+    /// Returns `None` when it will result in overflow.
+    ///
+    /// Overflow returns `None`.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use std::str::FromStr;
+    /// use chrono::{Months, NaiveDate, NaiveDateTime};
+    ///
+    /// assert_eq!(
+    ///     NaiveDate::from_ymd_opt(2014, 1, 1).unwrap().and_hms_opt(1, 0, 0).unwrap()
+    ///         .checked_add_months(Months::new(1)),
+    ///     Some(NaiveDate::from_ymd_opt(2014, 2, 1).unwrap().and_hms_opt(1, 0, 0).unwrap())
+    /// );
+    ///
+    /// assert_eq!(
+    ///     NaiveDate::from_ymd_opt(2014, 1, 1).unwrap().and_hms_opt(1, 0, 0).unwrap()
+    ///         .checked_add_months(Months::new(core::i32::MAX as u32 + 1)),
+    ///     None
+    /// );
+    /// ```
+    pub fn checked_add_months(self, rhs: Months) -> Option<NaiveDateTime> {
+        Some(Self { date: self.date.checked_add_months(rhs)?, time: self.time })
+    }
+
+    /// Subtracts given `Duration` from the current date and time.
+    ///
+    /// As a part of Chrono's [leap second handling](./struct.NaiveTime.html#leap-second-handling),
+    /// the subtraction assumes that **there is no leap second ever**,
+    /// except when the `NaiveDateTime` itself represents a leap second
+    /// in which case the assumption becomes that **there is exactly a single leap second ever**.
+    ///
+    /// Returns `None` when it will result in overflow.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{Duration, NaiveDate};
+    ///
+    /// let from_ymd = NaiveDate::from_ymd;
+    ///
+    /// let d = from_ymd(2016, 7, 8);
+    /// let hms = |h, m, s| d.and_hms_opt(h, m, s).unwrap();
+    /// assert_eq!(hms(3, 5, 7).checked_sub_signed(Duration::zero()),
+    ///            Some(hms(3, 5, 7)));
+    /// assert_eq!(hms(3, 5, 7).checked_sub_signed(Duration::seconds(1)),
+    ///            Some(hms(3, 5, 6)));
+    /// assert_eq!(hms(3, 5, 7).checked_sub_signed(Duration::seconds(-1)),
+    ///            Some(hms(3, 5, 8)));
+    /// assert_eq!(hms(3, 5, 7).checked_sub_signed(Duration::seconds(3600 + 60)),
+    ///            Some(hms(2, 4, 7)));
+    /// assert_eq!(hms(3, 5, 7).checked_sub_signed(Duration::seconds(86_400)),
+    ///            Some(from_ymd(2016, 7, 7).and_hms_opt(3, 5, 7).unwrap()));
+    ///
+    /// let hmsm = |h, m, s, milli| d.and_hms_milli_opt(h, m, s, milli).unwrap();
+    /// assert_eq!(hmsm(3, 5, 7, 450).checked_sub_signed(Duration::milliseconds(670)),
+    ///            Some(hmsm(3, 5, 6, 780)));
+    /// ```
+    ///
+    /// Overflow returns `None`.
+    ///
+    /// ```
+    /// # use chrono::{Duration, NaiveDate};
+    /// # let hms = |h, m, s| NaiveDate::from_ymd_opt(2016, 7, 8).unwrap().and_hms_opt(h, m, s).unwrap();
+    /// assert_eq!(hms(3, 5, 7).checked_sub_signed(Duration::days(1_000_000_000)), None);
+    /// ```
+    ///
+    /// Leap seconds are handled,
+    /// but the subtraction assumes that it is the only leap second happened.
+    ///
+    /// ```
+    /// # use chrono::{Duration, NaiveDate};
+    /// # let from_ymd = NaiveDate::from_ymd;
+    /// # let hmsm = |h, m, s, milli| from_ymd(2016, 7, 8).and_hms_milli_opt(h, m, s, milli).unwrap();
+    /// let leap = hmsm(3, 5, 59, 1_300);
+    /// assert_eq!(leap.checked_sub_signed(Duration::zero()),
+    ///            Some(hmsm(3, 5, 59, 1_300)));
+    /// assert_eq!(leap.checked_sub_signed(Duration::milliseconds(200)),
+    ///            Some(hmsm(3, 5, 59, 1_100)));
+    /// assert_eq!(leap.checked_sub_signed(Duration::milliseconds(500)),
+    ///            Some(hmsm(3, 5, 59, 800)));
+    /// assert_eq!(leap.checked_sub_signed(Duration::seconds(60)),
+    ///            Some(hmsm(3, 5, 0, 300)));
+    /// assert_eq!(leap.checked_sub_signed(Duration::days(1)),
+    ///            Some(from_ymd(2016, 7, 7).and_hms_milli_opt(3, 6, 0, 300).unwrap()));
+    /// ```
+    pub fn checked_sub_signed(self, rhs: OldDuration) -> Option<NaiveDateTime> {
+        let (time, rhs) = self.time.overflowing_sub_signed(rhs);
+
+        // early checking to avoid overflow in OldDuration::seconds
+        if rhs <= (-1 << MAX_SECS_BITS) || rhs >= (1 << MAX_SECS_BITS) {
+            return None;
+        }
+
+        let date = self.date.checked_sub_signed(OldDuration::seconds(rhs))?;
+        Some(NaiveDateTime { date, time })
+    }
+
+    /// Subtracts given `Months` from the current date and time.
+    ///
+    /// Returns `None` when it will result in overflow.
+    ///
+    /// Overflow returns `None`.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use std::str::FromStr;
+    /// use chrono::{Months, NaiveDate, NaiveDateTime};
+    ///
+    /// assert_eq!(
+    ///     NaiveDate::from_ymd_opt(2014, 1, 1).unwrap().and_hms_opt(1, 0, 0).unwrap()
+    ///         .checked_sub_months(Months::new(1)),
+    ///     Some(NaiveDate::from_ymd_opt(2013, 12, 1).unwrap().and_hms_opt(1, 0, 0).unwrap())
+    /// );
+    ///
+    /// assert_eq!(
+    ///     NaiveDate::from_ymd_opt(2014, 1, 1).unwrap().and_hms_opt(1, 0, 0).unwrap()
+    ///         .checked_sub_months(Months::new(core::i32::MAX as u32 + 1)),
+    ///     None
+    /// );
+    /// ```
+    pub fn checked_sub_months(self, rhs: Months) -> Option<NaiveDateTime> {
+        Some(Self { date: self.date.checked_sub_months(rhs)?, time: self.time })
+    }
+
+    /// Add a duration in [`Days`] to the date part of the `NaiveDateTime`
+    ///
+    /// Returns `None` if the resulting date would be out of range.
+    pub fn checked_add_days(self, days: Days) -> Option<Self> {
+        Some(Self { date: self.date.checked_add_days(days)?, ..self })
+    }
+
+    /// Subtract a duration in [`Days`] from the date part of the `NaiveDateTime`
+    ///
+    /// Returns `None` if the resulting date would be out of range.
+    pub fn checked_sub_days(self, days: Days) -> Option<Self> {
+        Some(Self { date: self.date.checked_sub_days(days)?, ..self })
+    }
+
+    /// Subtracts another `NaiveDateTime` from the current date and time.
+    /// This does not overflow or underflow at all.
+    ///
+    /// As a part of Chrono's [leap second handling](./struct.NaiveTime.html#leap-second-handling),
+    /// the subtraction assumes that **there is no leap second ever**,
+    /// except when any of the `NaiveDateTime`s themselves represents a leap second
+    /// in which case the assumption becomes that
+    /// **there are exactly one (or two) leap second(s) ever**.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{Duration, NaiveDate};
+    ///
+    /// let from_ymd = NaiveDate::from_ymd;
+    ///
+    /// let d = from_ymd(2016, 7, 8);
+    /// assert_eq!(d.and_hms_opt(3, 5, 7).unwrap().signed_duration_since(d.and_hms_opt(2, 4, 6).unwrap()),
+    ///            Duration::seconds(3600 + 60 + 1));
+    ///
+    /// // July 8 is 190th day in the year 2016
+    /// let d0 = from_ymd(2016, 1, 1);
+    /// assert_eq!(d.and_hms_milli_opt(0, 7, 6, 500).unwrap().signed_duration_since(d0.and_hms_opt(0, 0, 0).unwrap()),
+    ///            Duration::seconds(189 * 86_400 + 7 * 60 + 6) + Duration::milliseconds(500));
+    /// ```
+    ///
+    /// Leap seconds are handled, but the subtraction assumes that
+    /// there were no other leap seconds happened.
+    ///
+    /// ```
+    /// # use chrono::{Duration, NaiveDate};
+    /// # let from_ymd = NaiveDate::from_ymd;
+    /// let leap = from_ymd(2015, 6, 30).and_hms_milli_opt(23, 59, 59, 1_500).unwrap();
+    /// assert_eq!(leap.signed_duration_since(from_ymd(2015, 6, 30).and_hms_opt(23, 0, 0).unwrap()),
+    ///            Duration::seconds(3600) + Duration::milliseconds(500));
+    /// assert_eq!(from_ymd(2015, 7, 1).and_hms_opt(1, 0, 0).unwrap().signed_duration_since(leap),
+    ///            Duration::seconds(3600) - Duration::milliseconds(500));
+    /// ```
+    pub fn signed_duration_since(self, rhs: NaiveDateTime) -> OldDuration {
+        self.date.signed_duration_since(rhs.date) + self.time.signed_duration_since(rhs.time)
+    }
+
+    /// Formats the combined date and time with the specified formatting items.
+    /// Otherwise it is the same as the ordinary [`format`](#method.format) method.
+    ///
+    /// The `Iterator` of items should be `Clone`able,
+    /// since the resulting `DelayedFormat` value may be formatted multiple times.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::NaiveDate;
+    /// use chrono::format::strftime::StrftimeItems;
+    ///
+    /// let fmt = StrftimeItems::new("%Y-%m-%d %H:%M:%S");
+    /// let dt = NaiveDate::from_ymd_opt(2015, 9, 5).unwrap().and_hms_opt(23, 56, 4).unwrap();
+    /// assert_eq!(dt.format_with_items(fmt.clone()).to_string(), "2015-09-05 23:56:04");
+    /// assert_eq!(dt.format("%Y-%m-%d %H:%M:%S").to_string(),    "2015-09-05 23:56:04");
+    /// ```
+    ///
+    /// The resulting `DelayedFormat` can be formatted directly via the `Display` trait.
+    ///
+    /// ```
+    /// # use chrono::NaiveDate;
+    /// # use chrono::format::strftime::StrftimeItems;
+    /// # let fmt = StrftimeItems::new("%Y-%m-%d %H:%M:%S").clone();
+    /// # let dt = NaiveDate::from_ymd_opt(2015, 9, 5).unwrap().and_hms_opt(23, 56, 4).unwrap();
+    /// assert_eq!(format!("{}", dt.format_with_items(fmt)), "2015-09-05 23:56:04");
+    /// ```
+    #[cfg(any(feature = "alloc", feature = "std", test))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "alloc", feature = "std"))))]
+    #[inline]
+    pub fn format_with_items<'a, I, B>(&self, items: I) -> DelayedFormat<I>
+    where
+        I: Iterator<Item = B> + Clone,
+        B: Borrow<Item<'a>>,
+    {
+        DelayedFormat::new(Some(self.date), Some(self.time), items)
+    }
+
+    /// Formats the combined date and time with the specified format string.
+    /// See the [`format::strftime` module](../format/strftime/index.html)
+    /// on the supported escape sequences.
+    ///
+    /// This returns a `DelayedFormat`,
+    /// which gets converted to a string only when actual formatting happens.
+    /// You may use the `to_string` method to get a `String`,
+    /// or just feed it into `print!` and other formatting macros.
+    /// (In this way it avoids the redundant memory allocation.)
+    ///
+    /// A wrong format string does *not* issue an error immediately.
+    /// Rather, converting or formatting the `DelayedFormat` fails.
+    /// You are recommended to immediately use `DelayedFormat` for this reason.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::NaiveDate;
+    ///
+    /// let dt = NaiveDate::from_ymd_opt(2015, 9, 5).unwrap().and_hms_opt(23, 56, 4).unwrap();
+    /// assert_eq!(dt.format("%Y-%m-%d %H:%M:%S").to_string(), "2015-09-05 23:56:04");
+    /// assert_eq!(dt.format("around %l %p on %b %-d").to_string(), "around 11 PM on Sep 5");
+    /// ```
+    ///
+    /// The resulting `DelayedFormat` can be formatted directly via the `Display` trait.
+    ///
+    /// ```
+    /// # use chrono::NaiveDate;
+    /// # let dt = NaiveDate::from_ymd_opt(2015, 9, 5).unwrap().and_hms_opt(23, 56, 4).unwrap();
+    /// assert_eq!(format!("{}", dt.format("%Y-%m-%d %H:%M:%S")), "2015-09-05 23:56:04");
+    /// assert_eq!(format!("{}", dt.format("around %l %p on %b %-d")), "around 11 PM on Sep 5");
+    /// ```
+    #[cfg(any(feature = "alloc", feature = "std", test))]
+    #[cfg_attr(docsrs, doc(cfg(any(feature = "alloc", feature = "std"))))]
+    #[inline]
+    pub fn format<'a>(&self, fmt: &'a str) -> DelayedFormat<StrftimeItems<'a>> {
+        self.format_with_items(StrftimeItems::new(fmt))
+    }
+
+    /// Converts the `NaiveDateTime` into the timezone-aware `DateTime<Tz>`
+    /// with the provided timezone, if possible.
+    ///
+    /// This can fail in cases where the local time represented by the `NaiveDateTime`
+    /// is not a valid local timestamp in the target timezone due to an offset transition
+    /// for example if the target timezone had a change from +00:00 to +01:00
+    /// occuring at 2015-09-05 22:59:59, then a local time of 2015-09-05 23:56:04
+    /// could never occur. Similarly, if the offset transitioned in the opposite direction
+    /// then there would be two local times of 2015-09-05 23:56:04, one at +00:00 and one
+    /// at +01:00.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, Utc};
+    /// let dt = NaiveDate::from_ymd_opt(2015, 9, 5).unwrap().and_hms_opt(23, 56, 4).unwrap().and_local_timezone(Utc).unwrap();
+    /// assert_eq!(dt.timezone(), Utc);
+    pub fn and_local_timezone<Tz: TimeZone>(&self, tz: Tz) -> LocalResult<DateTime<Tz>> {
+        tz.from_local_datetime(self)
+    }
+
+    /// The minimum possible `NaiveDateTime`.
+    pub const MIN: Self = Self { date: NaiveDate::MIN, time: NaiveTime::MIN };
+    /// The maximum possible `NaiveDateTime`.
+    pub const MAX: Self = Self { date: NaiveDate::MAX, time: NaiveTime::MAX };
+
+    /// Creates a new [NaiveDateTime] from milliseconds or microseconds since the UNIX epoch.
+    ///
+    /// This is a private function used by [from_timestamp_millis] and [from_timestamp_micros].
+    #[inline]
+    fn from_timestamp_unit(value: i64, unit: TimestampUnit) -> Option<NaiveDateTime> {
+        let (secs, subsecs) =
+            (value / i64::from(unit.per_second()), value % i64::from(unit.per_second()));
+
+        match subsecs.cmp(&0) {
+            Ordering::Less => {
+                // in the case where our subsec part is negative, then we are actually in the earlier second
+                // hence we subtract one from the seconds part, and we then add a whole second worth of nanos
+                // to our nanos part. Due to the use of u32 datatype, it is more convenient to subtract
+                // the absolute value of the subsec nanos from a whole second worth of nanos
+                let nsecs = u32::try_from(subsecs.abs()).ok()? * unit.nanos_per();
+                NaiveDateTime::from_timestamp_opt(
+                    secs.checked_sub(1)?,
+                    NANOS_IN_SECOND.checked_sub(nsecs)?,
+                )
+            }
+            Ordering::Equal => NaiveDateTime::from_timestamp_opt(secs, 0),
+            Ordering::Greater => {
+                // convert the subsec millis into nanosecond scale so they can be supplied
+                // as the nanoseconds parameter
+                let nsecs = u32::try_from(subsecs).ok()? * unit.nanos_per();
+                NaiveDateTime::from_timestamp_opt(secs, nsecs)
+            }
+        }
+    }
+}
+
+impl Datelike for NaiveDateTime {
+    /// Returns the year number in the [calendar date](./index.html#calendar-date).
+    ///
+    /// See also the [`NaiveDate::year`] method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Datelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 25).unwrap().and_hms_opt(12, 34, 56).unwrap();
+    /// assert_eq!(dt.year(), 2015);
+    /// ```
+    #[inline]
+    fn year(&self) -> i32 {
+        self.date.year()
+    }
+
+    /// Returns the month number starting from 1.
+    ///
+    /// The return value ranges from 1 to 12.
+    ///
+    /// See also the [`NaiveDate::month`](./struct.NaiveDate.html#method.month) method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Datelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 25).unwrap().and_hms_opt(12, 34, 56).unwrap();
+    /// assert_eq!(dt.month(), 9);
+    /// ```
+    #[inline]
+    fn month(&self) -> u32 {
+        self.date.month()
+    }
+
+    /// Returns the month number starting from 0.
+    ///
+    /// The return value ranges from 0 to 11.
+    ///
+    /// See also the [`NaiveDate::month0`](./struct.NaiveDate.html#method.month0) method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Datelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 25).unwrap().and_hms_opt(12, 34, 56).unwrap();
+    /// assert_eq!(dt.month0(), 8);
+    /// ```
+    #[inline]
+    fn month0(&self) -> u32 {
+        self.date.month0()
+    }
+
+    /// Returns the day of month starting from 1.
+    ///
+    /// The return value ranges from 1 to 31. (The last day of month differs by months.)
+    ///
+    /// See also the [`NaiveDate::day`](./struct.NaiveDate.html#method.day) method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Datelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 25).unwrap().and_hms_opt(12, 34, 56).unwrap();
+    /// assert_eq!(dt.day(), 25);
+    /// ```
+    #[inline]
+    fn day(&self) -> u32 {
+        self.date.day()
+    }
+
+    /// Returns the day of month starting from 0.
+    ///
+    /// The return value ranges from 0 to 30. (The last day of month differs by months.)
+    ///
+    /// See also the [`NaiveDate::day0`](./struct.NaiveDate.html#method.day0) method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Datelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 25).unwrap().and_hms_opt(12, 34, 56).unwrap();
+    /// assert_eq!(dt.day0(), 24);
+    /// ```
+    #[inline]
+    fn day0(&self) -> u32 {
+        self.date.day0()
+    }
+
+    /// Returns the day of year starting from 1.
+    ///
+    /// The return value ranges from 1 to 366. (The last day of year differs by years.)
+    ///
+    /// See also the [`NaiveDate::ordinal`](./struct.NaiveDate.html#method.ordinal) method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Datelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 25).unwrap().and_hms_opt(12, 34, 56).unwrap();
+    /// assert_eq!(dt.ordinal(), 268);
+    /// ```
+    #[inline]
+    fn ordinal(&self) -> u32 {
+        self.date.ordinal()
+    }
+
+    /// Returns the day of year starting from 0.
+    ///
+    /// The return value ranges from 0 to 365. (The last day of year differs by years.)
+    ///
+    /// See also the [`NaiveDate::ordinal0`](./struct.NaiveDate.html#method.ordinal0) method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Datelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 25).unwrap().and_hms_opt(12, 34, 56).unwrap();
+    /// assert_eq!(dt.ordinal0(), 267);
+    /// ```
+    #[inline]
+    fn ordinal0(&self) -> u32 {
+        self.date.ordinal0()
+    }
+
+    /// Returns the day of week.
+    ///
+    /// See also the [`NaiveDate::weekday`](./struct.NaiveDate.html#method.weekday) method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Datelike, Weekday};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 25).unwrap().and_hms_opt(12, 34, 56).unwrap();
+    /// assert_eq!(dt.weekday(), Weekday::Fri);
+    /// ```
+    #[inline]
+    fn weekday(&self) -> Weekday {
+        self.date.weekday()
+    }
+
+    #[inline]
+    fn iso_week(&self) -> IsoWeek {
+        self.date.iso_week()
+    }
+
+    /// Makes a new `NaiveDateTime` with the year number changed.
+    ///
+    /// Returns `None` when the resulting `NaiveDateTime` would be invalid.
+    ///
+    /// See also the [`NaiveDate::with_year`] method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Datelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 25).unwrap().and_hms_opt(12, 34, 56).unwrap();
+    /// assert_eq!(dt.with_year(2016), Some(NaiveDate::from_ymd_opt(2016, 9, 25).unwrap().and_hms_opt(12, 34, 56).unwrap()));
+    /// assert_eq!(dt.with_year(-308), Some(NaiveDate::from_ymd_opt(-308, 9, 25).unwrap().and_hms_opt(12, 34, 56).unwrap()));
+    /// ```
+    #[inline]
+    fn with_year(&self, year: i32) -> Option<NaiveDateTime> {
+        self.date.with_year(year).map(|d| NaiveDateTime { date: d, ..*self })
+    }
+
+    /// Makes a new `NaiveDateTime` with the month number (starting from 1) changed.
+    ///
+    /// Returns `None` when the resulting `NaiveDateTime` would be invalid.
+    ///
+    /// See also the [`NaiveDate::with_month`] method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Datelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 30).unwrap().and_hms_opt(12, 34, 56).unwrap();
+    /// assert_eq!(dt.with_month(10), Some(NaiveDate::from_ymd_opt(2015, 10, 30).unwrap().and_hms_opt(12, 34, 56).unwrap()));
+    /// assert_eq!(dt.with_month(13), None); // no month 13
+    /// assert_eq!(dt.with_month(2), None); // no February 30
+    /// ```
+    #[inline]
+    fn with_month(&self, month: u32) -> Option<NaiveDateTime> {
+        self.date.with_month(month).map(|d| NaiveDateTime { date: d, ..*self })
+    }
+
+    /// Makes a new `NaiveDateTime` with the month number (starting from 0) changed.
+    ///
+    /// Returns `None` when the resulting `NaiveDateTime` would be invalid.
+    ///
+    /// See also the [`NaiveDate::with_month0`] method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Datelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 30).unwrap().and_hms_opt(12, 34, 56).unwrap();
+    /// assert_eq!(dt.with_month0(9), Some(NaiveDate::from_ymd_opt(2015, 10, 30).unwrap().and_hms_opt(12, 34, 56).unwrap()));
+    /// assert_eq!(dt.with_month0(12), None); // no month 13
+    /// assert_eq!(dt.with_month0(1), None); // no February 30
+    /// ```
+    #[inline]
+    fn with_month0(&self, month0: u32) -> Option<NaiveDateTime> {
+        self.date.with_month0(month0).map(|d| NaiveDateTime { date: d, ..*self })
+    }
+
+    /// Makes a new `NaiveDateTime` with the day of month (starting from 1) changed.
+    ///
+    /// Returns `None` when the resulting `NaiveDateTime` would be invalid.
+    ///
+    /// See also the [`NaiveDate::with_day`] method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Datelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 8).unwrap().and_hms_opt(12, 34, 56).unwrap();
+    /// assert_eq!(dt.with_day(30), Some(NaiveDate::from_ymd_opt(2015, 9, 30).unwrap().and_hms_opt(12, 34, 56).unwrap()));
+    /// assert_eq!(dt.with_day(31), None); // no September 31
+    /// ```
+    #[inline]
+    fn with_day(&self, day: u32) -> Option<NaiveDateTime> {
+        self.date.with_day(day).map(|d| NaiveDateTime { date: d, ..*self })
+    }
+
+    /// Makes a new `NaiveDateTime` with the day of month (starting from 0) changed.
+    ///
+    /// Returns `None` when the resulting `NaiveDateTime` would be invalid.
+    ///
+    /// See also the [`NaiveDate::with_day0`] method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Datelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 8).unwrap().and_hms_opt(12, 34, 56).unwrap();
+    /// assert_eq!(dt.with_day0(29), Some(NaiveDate::from_ymd_opt(2015, 9, 30).unwrap().and_hms_opt(12, 34, 56).unwrap()));
+    /// assert_eq!(dt.with_day0(30), None); // no September 31
+    /// ```
+    #[inline]
+    fn with_day0(&self, day0: u32) -> Option<NaiveDateTime> {
+        self.date.with_day0(day0).map(|d| NaiveDateTime { date: d, ..*self })
+    }
+
+    /// Makes a new `NaiveDateTime` with the day of year (starting from 1) changed.
+    ///
+    /// Returns `None` when the resulting `NaiveDateTime` would be invalid.
+    ///
+    /// See also the [`NaiveDate::with_ordinal`] method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Datelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 8).unwrap().and_hms_opt(12, 34, 56).unwrap();
+    /// assert_eq!(dt.with_ordinal(60),
+    ///            Some(NaiveDate::from_ymd_opt(2015, 3, 1).unwrap().and_hms_opt(12, 34, 56).unwrap()));
+    /// assert_eq!(dt.with_ordinal(366), None); // 2015 had only 365 days
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2016, 9, 8).unwrap().and_hms_opt(12, 34, 56).unwrap();
+    /// assert_eq!(dt.with_ordinal(60),
+    ///            Some(NaiveDate::from_ymd_opt(2016, 2, 29).unwrap().and_hms_opt(12, 34, 56).unwrap()));
+    /// assert_eq!(dt.with_ordinal(366),
+    ///            Some(NaiveDate::from_ymd_opt(2016, 12, 31).unwrap().and_hms_opt(12, 34, 56).unwrap()));
+    /// ```
+    #[inline]
+    fn with_ordinal(&self, ordinal: u32) -> Option<NaiveDateTime> {
+        self.date.with_ordinal(ordinal).map(|d| NaiveDateTime { date: d, ..*self })
+    }
+
+    /// Makes a new `NaiveDateTime` with the day of year (starting from 0) changed.
+    ///
+    /// Returns `None` when the resulting `NaiveDateTime` would be invalid.
+    ///
+    /// See also the [`NaiveDate::with_ordinal0`] method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Datelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 8).unwrap().and_hms_opt(12, 34, 56).unwrap();
+    /// assert_eq!(dt.with_ordinal0(59),
+    ///            Some(NaiveDate::from_ymd_opt(2015, 3, 1).unwrap().and_hms_opt(12, 34, 56).unwrap()));
+    /// assert_eq!(dt.with_ordinal0(365), None); // 2015 had only 365 days
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2016, 9, 8).unwrap().and_hms_opt(12, 34, 56).unwrap();
+    /// assert_eq!(dt.with_ordinal0(59),
+    ///            Some(NaiveDate::from_ymd_opt(2016, 2, 29).unwrap().and_hms_opt(12, 34, 56).unwrap()));
+    /// assert_eq!(dt.with_ordinal0(365),
+    ///            Some(NaiveDate::from_ymd_opt(2016, 12, 31).unwrap().and_hms_opt(12, 34, 56).unwrap()));
+    /// ```
+    #[inline]
+    fn with_ordinal0(&self, ordinal0: u32) -> Option<NaiveDateTime> {
+        self.date.with_ordinal0(ordinal0).map(|d| NaiveDateTime { date: d, ..*self })
+    }
+}
+
+impl Timelike for NaiveDateTime {
+    /// Returns the hour number from 0 to 23.
+    ///
+    /// See also the [`NaiveTime::hour`] method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Timelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 8).unwrap().and_hms_milli_opt(12, 34, 56, 789).unwrap();
+    /// assert_eq!(dt.hour(), 12);
+    /// ```
+    #[inline]
+    fn hour(&self) -> u32 {
+        self.time.hour()
+    }
+
+    /// Returns the minute number from 0 to 59.
+    ///
+    /// See also the [`NaiveTime::minute`] method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Timelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 8).unwrap().and_hms_milli_opt(12, 34, 56, 789).unwrap();
+    /// assert_eq!(dt.minute(), 34);
+    /// ```
+    #[inline]
+    fn minute(&self) -> u32 {
+        self.time.minute()
+    }
+
+    /// Returns the second number from 0 to 59.
+    ///
+    /// See also the [`NaiveTime::second`] method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Timelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 8).unwrap().and_hms_milli_opt(12, 34, 56, 789).unwrap();
+    /// assert_eq!(dt.second(), 56);
+    /// ```
+    #[inline]
+    fn second(&self) -> u32 {
+        self.time.second()
+    }
+
+    /// Returns the number of nanoseconds since the whole non-leap second.
+    /// The range from 1,000,000,000 to 1,999,999,999 represents
+    /// the [leap second](./struct.NaiveTime.html#leap-second-handling).
+    ///
+    /// See also the [`NaiveTime::nanosecond`] method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Timelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 8).unwrap().and_hms_milli_opt(12, 34, 56, 789).unwrap();
+    /// assert_eq!(dt.nanosecond(), 789_000_000);
+    /// ```
+    #[inline]
+    fn nanosecond(&self) -> u32 {
+        self.time.nanosecond()
+    }
+
+    /// Makes a new `NaiveDateTime` with the hour number changed.
+    ///
+    /// Returns `None` when the resulting `NaiveDateTime` would be invalid.
+    ///
+    /// See also the [`NaiveTime::with_hour`] method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Timelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 8).unwrap().and_hms_milli_opt(12, 34, 56, 789).unwrap();
+    /// assert_eq!(dt.with_hour(7),
+    ///            Some(NaiveDate::from_ymd_opt(2015, 9, 8).unwrap().and_hms_milli_opt(7, 34, 56, 789).unwrap()));
+    /// assert_eq!(dt.with_hour(24), None);
+    /// ```
+    #[inline]
+    fn with_hour(&self, hour: u32) -> Option<NaiveDateTime> {
+        self.time.with_hour(hour).map(|t| NaiveDateTime { time: t, ..*self })
+    }
+
+    /// Makes a new `NaiveDateTime` with the minute number changed.
+    ///
+    /// Returns `None` when the resulting `NaiveDateTime` would be invalid.
+    ///
+    /// See also the
+    /// [`NaiveTime::with_minute`] method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Timelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 8).unwrap().and_hms_milli_opt(12, 34, 56, 789).unwrap();
+    /// assert_eq!(dt.with_minute(45),
+    ///            Some(NaiveDate::from_ymd_opt(2015, 9, 8).unwrap().and_hms_milli_opt(12, 45, 56, 789).unwrap()));
+    /// assert_eq!(dt.with_minute(60), None);
+    /// ```
+    #[inline]
+    fn with_minute(&self, min: u32) -> Option<NaiveDateTime> {
+        self.time.with_minute(min).map(|t| NaiveDateTime { time: t, ..*self })
+    }
+
+    /// Makes a new `NaiveDateTime` with the second number changed.
+    ///
+    /// Returns `None` when the resulting `NaiveDateTime` would be invalid. As
+    /// with the [`NaiveDateTime::second`] method, the input range is
+    /// restricted to 0 through 59.
+    ///
+    /// See also the [`NaiveTime::with_second`] method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Timelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 8).unwrap().and_hms_milli_opt(12, 34, 56, 789).unwrap();
+    /// assert_eq!(dt.with_second(17),
+    ///            Some(NaiveDate::from_ymd_opt(2015, 9, 8).unwrap().and_hms_milli_opt(12, 34, 17, 789).unwrap()));
+    /// assert_eq!(dt.with_second(60), None);
+    /// ```
+    #[inline]
+    fn with_second(&self, sec: u32) -> Option<NaiveDateTime> {
+        self.time.with_second(sec).map(|t| NaiveDateTime { time: t, ..*self })
+    }
+
+    /// Makes a new `NaiveDateTime` with nanoseconds since the whole non-leap second changed.
+    ///
+    /// Returns `None` when the resulting `NaiveDateTime` would be invalid.
+    /// As with the [`NaiveDateTime::nanosecond`] method,
+    /// the input range can exceed 1,000,000,000 for leap seconds.
+    ///
+    /// See also the [`NaiveTime::with_nanosecond`] method.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{NaiveDate, NaiveDateTime, Timelike};
+    ///
+    /// let dt: NaiveDateTime = NaiveDate::from_ymd_opt(2015, 9, 8).unwrap().and_hms_milli_opt(12, 34, 56, 789).unwrap();
+    /// assert_eq!(dt.with_nanosecond(333_333_333),
+    ///            Some(NaiveDate::from_ymd_opt(2015, 9, 8).unwrap().and_hms_nano_opt(12, 34, 56, 333_333_333).unwrap()));
+    /// assert_eq!(dt.with_nanosecond(1_333_333_333), // leap second
+    ///            Some(NaiveDate::from_ymd_opt(2015, 9, 8).unwrap().and_hms_nano_opt(12, 34, 56, 1_333_333_333).unwrap()));
+    /// assert_eq!(dt.with_nanosecond(2_000_000_000), None);
+    /// ```
+    #[inline]
+    fn with_nanosecond(&self, nano: u32) -> Option<NaiveDateTime> {
+        self.time.with_nanosecond(nano).map(|t| NaiveDateTime { time: t, ..*self })
+    }
+}
+
+/// An addition of `Duration` to `NaiveDateTime` yields another `NaiveDateTime`.
+///
+/// As a part of Chrono's [leap second handling](./struct.NaiveTime.html#leap-second-handling),
+/// the addition assumes that **there is no leap second ever**,
+/// except when the `NaiveDateTime` itself represents a leap second
+/// in which case the assumption becomes that **there is exactly a single leap second ever**.
+///
+/// Panics on underflow or overflow. Use [`NaiveDateTime::checked_add_signed`]
+/// to detect that.
+///
+/// # Example
+///
+/// ```
+/// use chrono::{Duration, NaiveDate};
+///
+/// let from_ymd = NaiveDate::from_ymd;
+///
+/// let d = from_ymd(2016, 7, 8);
+/// let hms = |h, m, s| d.and_hms_opt(h, m, s).unwrap();
+/// assert_eq!(hms(3, 5, 7) + Duration::zero(),             hms(3, 5, 7));
+/// assert_eq!(hms(3, 5, 7) + Duration::seconds(1),         hms(3, 5, 8));
+/// assert_eq!(hms(3, 5, 7) + Duration::seconds(-1),        hms(3, 5, 6));
+/// assert_eq!(hms(3, 5, 7) + Duration::seconds(3600 + 60), hms(4, 6, 7));
+/// assert_eq!(hms(3, 5, 7) + Duration::seconds(86_400),
+///            from_ymd(2016, 7, 9).and_hms_opt(3, 5, 7).unwrap());
+/// assert_eq!(hms(3, 5, 7) + Duration::days(365),
+///            from_ymd(2017, 7, 8).and_hms_opt(3, 5, 7).unwrap());
+///
+/// let hmsm = |h, m, s, milli| d.and_hms_milli_opt(h, m, s, milli).unwrap();
+/// assert_eq!(hmsm(3, 5, 7, 980) + Duration::milliseconds(450), hmsm(3, 5, 8, 430));
+/// ```
+///
+/// Leap seconds are handled,
+/// but the addition assumes that it is the only leap second happened.
+///
+/// ```
+/// # use chrono::{Duration, NaiveDate};
+/// # let from_ymd = NaiveDate::from_ymd;
+/// # let hmsm = |h, m, s, milli| from_ymd(2016, 7, 8).and_hms_milli_opt(h, m, s, milli).unwrap();
+/// let leap = hmsm(3, 5, 59, 1_300);
+/// assert_eq!(leap + Duration::zero(),             hmsm(3, 5, 59, 1_300));
+/// assert_eq!(leap + Duration::milliseconds(-500), hmsm(3, 5, 59, 800));
+/// assert_eq!(leap + Duration::milliseconds(500),  hmsm(3, 5, 59, 1_800));
+/// assert_eq!(leap + Duration::milliseconds(800),  hmsm(3, 6, 0, 100));
+/// assert_eq!(leap + Duration::seconds(10),        hmsm(3, 6, 9, 300));
+/// assert_eq!(leap + Duration::seconds(-10),       hmsm(3, 5, 50, 300));
+/// assert_eq!(leap + Duration::days(1),
+///            from_ymd(2016, 7, 9).and_hms_milli_opt(3, 5, 59, 300).unwrap());
+/// ```
+impl Add<OldDuration> for NaiveDateTime {
+    type Output = NaiveDateTime;
+
+    #[inline]
+    fn add(self, rhs: OldDuration) -> NaiveDateTime {
+        self.checked_add_signed(rhs).expect("`NaiveDateTime + Duration` overflowed")
+    }
+}
+
+impl AddAssign<OldDuration> for NaiveDateTime {
+    #[inline]
+    fn add_assign(&mut self, rhs: OldDuration) {
+        *self = self.add(rhs);
+    }
+}
+
+impl Add<Months> for NaiveDateTime {
+    type Output = NaiveDateTime;
+
+    /// An addition of months to `NaiveDateTime` clamped to valid days in resulting month.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the resulting date would be out of range.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use chrono::{Duration, NaiveDateTime, Months, NaiveDate};
+    /// use std::str::FromStr;
+    ///
+    /// assert_eq!(
+    ///     NaiveDate::from_ymd_opt(2014, 1, 1).unwrap().and_hms_opt(1, 0, 0).unwrap() + Months::new(1),
+    ///     NaiveDate::from_ymd_opt(2014, 2, 1).unwrap().and_hms_opt(1, 0, 0).unwrap()
+    /// );
+    /// assert_eq!(
+    ///     NaiveDate::from_ymd_opt(2014, 1, 1).unwrap().and_hms_opt(0, 2, 0).unwrap() + Months::new(11),
+    ///     NaiveDate::from_ymd_opt(2014, 12, 1).unwrap().and_hms_opt(0, 2, 0).unwrap()
+    /// );
+    /// assert_eq!(
+    ///     NaiveDate::from_ymd_opt(2014, 1, 1).unwrap().and_hms_opt(0, 0, 3).unwrap() + Months::new(12),
+    ///     NaiveDate::from_ymd_opt(2015, 1, 1).unwrap().and_hms_opt(0, 0, 3).unwrap()
+    /// );
+    /// assert_eq!(
+    ///     NaiveDate::from_ymd_opt(2014, 1, 1).unwrap().and_hms_opt(0, 0, 4).unwrap() + Months::new(13),
+    ///     NaiveDate::from_ymd_opt(2015, 2, 1).unwrap().and_hms_opt(0, 0, 4).unwrap()
+    /// );
+    /// assert_eq!(
+    ///     NaiveDate::from_ymd_opt(2014, 1, 31).unwrap().and_hms_opt(0, 5, 0).unwrap() + Months::new(1),
+    ///     NaiveDate::from_ymd_opt(2014, 2, 28).unwrap().and_hms_opt(0, 5, 0).unwrap()
+    /// );
+    /// assert_eq!(
+    ///     NaiveDate::from_ymd_opt(2020, 1, 31).unwrap().and_hms_opt(6, 0, 0).unwrap() + Months::new(1),
+    ///     NaiveDate::from_ymd_opt(2020, 2, 29).unwrap().and_hms_opt(6, 0, 0).unwrap()
+    /// );
+    /// ```
+    fn add(self, rhs: Months) -> Self::Output {
+        Self { date: self.date.checked_add_months(rhs).unwrap(), time: self.time }
+    }
+}
+
+/// A subtraction of `Duration` from `NaiveDateTime` yields another `NaiveDateTime`.
+/// It is the same as the addition with a negated `Duration`.
+///
+/// As a part of Chrono's [leap second handling](./struct.NaiveTime.html#leap-second-handling),
+/// the addition assumes that **there is no leap second ever**,
+/// except when the `NaiveDateTime` itself represents a leap second
+/// in which case the assumption becomes that **there is exactly a single leap second ever**.
+///
+/// Panics on underflow or overflow. Use [`NaiveDateTime::checked_sub_signed`]
+/// to detect that.
+///
+/// # Example
+///
+/// ```
+/// use chrono::{Duration, NaiveDate};
+///
+/// let from_ymd = NaiveDate::from_ymd;
+///
+/// let d = from_ymd(2016, 7, 8);
+/// let hms = |h, m, s| d.and_hms_opt(h, m, s).unwrap();
+/// assert_eq!(hms(3, 5, 7) - Duration::zero(),             hms(3, 5, 7));
+/// assert_eq!(hms(3, 5, 7) - Duration::seconds(1),         hms(3, 5, 6));
+/// assert_eq!(hms(3, 5, 7) - Duration::seconds(-1),        hms(3, 5, 8));
+/// assert_eq!(hms(3, 5, 7) - Duration::seconds(3600 + 60), hms(2, 4, 7));
+/// assert_eq!(hms(3, 5, 7) - Duration::seconds(86_400),
+///            from_ymd(2016, 7, 7).and_hms_opt(3, 5, 7).unwrap());
+/// assert_eq!(hms(3, 5, 7) - Duration::days(365),
+///            from_ymd(2015, 7, 9).and_hms_opt(3, 5, 7).unwrap());
+///
+/// let hmsm = |h, m, s, milli| d.and_hms_milli_opt(h, m, s, milli).unwrap();
+/// assert_eq!(hmsm(3, 5, 7, 450) - Duration::milliseconds(670), hmsm(3, 5, 6, 780));
+/// ```
+///
+/// Leap seconds are handled,
+/// but the subtraction assumes that it is the only leap second happened.
+///
+/// ```
+/// # use chrono::{Duration, NaiveDate};
+/// # let from_ymd = NaiveDate::from_ymd;
+/// # let hmsm = |h, m, s, milli| from_ymd(2016, 7, 8).and_hms_milli_opt(h, m, s, milli).unwrap();
+/// let leap = hmsm(3, 5, 59, 1_300);
+/// assert_eq!(leap - Duration::zero(),            hmsm(3, 5, 59, 1_300));
+/// assert_eq!(leap - Duration::milliseconds(200), hmsm(3, 5, 59, 1_100));
+/// assert_eq!(leap - Duration::milliseconds(500), hmsm(3, 5, 59, 800));
+/// assert_eq!(leap - Duration::seconds(60),       hmsm(3, 5, 0, 300));
+/// assert_eq!(leap - Duration::days(1),
+///            from_ymd(2016, 7, 7).and_hms_milli_opt(3, 6, 0, 300).unwrap());
+/// ```
+impl Sub<OldDuration> for NaiveDateTime {
+    type Output = NaiveDateTime;
+
+    #[inline]
+    fn sub(self, rhs: OldDuration) -> NaiveDateTime {
+        self.checked_sub_signed(rhs).expect("`NaiveDateTime - Duration` overflowed")
+    }
+}
+
+impl SubAssign<OldDuration> for NaiveDateTime {
+    #[inline]
+    fn sub_assign(&mut self, rhs: OldDuration) {
+        *self = self.sub(rhs);
+    }
+}
+
+/// A subtraction of Months from `NaiveDateTime` clamped to valid days in resulting month.
+///
+/// # Panics
+///
+/// Panics if the resulting date would be out of range.
+///
+/// # Example
+///
+/// ```
+/// use chrono::{Duration, NaiveDateTime, Months, NaiveDate};
+/// use std::str::FromStr;
+///
+/// assert_eq!(
+///     NaiveDate::from_ymd_opt(2014, 01, 01).unwrap().and_hms_opt(01, 00, 00).unwrap() - Months::new(11),
+///     NaiveDate::from_ymd_opt(2013, 02, 01).unwrap().and_hms_opt(01, 00, 00).unwrap()
+/// );
+/// assert_eq!(
+///     NaiveDate::from_ymd_opt(2014, 01, 01).unwrap().and_hms_opt(00, 02, 00).unwrap() - Months::new(12),
+///     NaiveDate::from_ymd_opt(2013, 01, 01).unwrap().and_hms_opt(00, 02, 00).unwrap()
+/// );
+/// assert_eq!(
+///     NaiveDate::from_ymd_opt(2014, 01, 01).unwrap().and_hms_opt(00, 00, 03).unwrap() - Months::new(13),
+///     NaiveDate::from_ymd_opt(2012, 12, 01).unwrap().and_hms_opt(00, 00, 03).unwrap()
+/// );
+/// ```
+impl Sub<Months> for NaiveDateTime {
+    type Output = NaiveDateTime;
+
+    fn sub(self, rhs: Months) -> Self::Output {
+        Self { date: self.date.checked_sub_months(rhs).unwrap(), time: self.time }
+    }
+}
+
+/// Subtracts another `NaiveDateTime` from the current date and time.
+/// This does not overflow or underflow at all.
+///
+/// As a part of Chrono's [leap second handling](./struct.NaiveTime.html#leap-second-handling),
+/// the subtraction assumes that **there is no leap second ever**,
+/// except when any of the `NaiveDateTime`s themselves represents a leap second
+/// in which case the assumption becomes that
+/// **there are exactly one (or two) leap second(s) ever**.
+///
+/// The implementation is a wrapper around [`NaiveDateTime::signed_duration_since`].
+///
+/// # Example
+///
+/// ```
+/// use chrono::{Duration, NaiveDate};
+///
+/// let from_ymd = NaiveDate::from_ymd;
+///
+/// let d = from_ymd(2016, 7, 8);
+/// assert_eq!(d.and_hms_opt(3, 5, 7).unwrap() - d.and_hms_opt(2, 4, 6).unwrap(), Duration::seconds(3600 + 60 + 1));
+///
+/// // July 8 is 190th day in the year 2016
+/// let d0 = from_ymd(2016, 1, 1);
+/// assert_eq!(d.and_hms_milli_opt(0, 7, 6, 500).unwrap() - d0.and_hms_opt(0, 0, 0).unwrap(),
+///            Duration::seconds(189 * 86_400 + 7 * 60 + 6) + Duration::milliseconds(500));
+/// ```
+///
+/// Leap seconds are handled, but the subtraction assumes that no other leap
+/// seconds happened.
+///
+/// ```
+/// # use chrono::{Duration, NaiveDate};
+/// # let from_ymd = NaiveDate::from_ymd;
+/// let leap = from_ymd(2015, 6, 30).and_hms_milli_opt(23, 59, 59, 1_500).unwrap();
+/// assert_eq!(leap - from_ymd(2015, 6, 30).and_hms_opt(23, 0, 0).unwrap(),
+///            Duration::seconds(3600) + Duration::milliseconds(500));
+/// assert_eq!(from_ymd(2015, 7, 1).and_hms_opt(1, 0, 0).unwrap() - leap,
+///            Duration::seconds(3600) - Duration::milliseconds(500));
+/// ```
+impl Sub<NaiveDateTime> for NaiveDateTime {
+    type Output = OldDuration;
+
+    #[inline]
+    fn sub(self, rhs: NaiveDateTime) -> OldDuration {
+        self.signed_duration_since(rhs)
+    }
+}
+
+impl Add<Days> for NaiveDateTime {
+    type Output = NaiveDateTime;
+
+    fn add(self, days: Days) -> Self::Output {
+        self.checked_add_days(days).unwrap()
+    }
+}
+
+impl Sub<Days> for NaiveDateTime {
+    type Output = NaiveDateTime;
+
+    fn sub(self, days: Days) -> Self::Output {
+        self.checked_sub_days(days).unwrap()
+    }
+}
+
+/// The `Debug` output of the naive date and time `dt` is the same as
+/// [`dt.format("%Y-%m-%dT%H:%M:%S%.f")`](crate::format::strftime).
+///
+/// The string printed can be readily parsed via the `parse` method on `str`.
+///
+/// It should be noted that, for leap seconds not on the minute boundary,
+/// it may print a representation not distinguishable from non-leap seconds.
+/// This doesn't matter in practice, since such leap seconds never happened.
+/// (By the time of the first leap second on 1972-06-30,
+/// every time zone offset around the world has standardized to the 5-minute alignment.)
+///
+/// # Example
+///
+/// ```
+/// use chrono::NaiveDate;
+///
+/// let dt = NaiveDate::from_ymd_opt(2016, 11, 15).unwrap().and_hms_opt(7, 39, 24).unwrap();
+/// assert_eq!(format!("{:?}", dt), "2016-11-15T07:39:24");
+/// ```
+///
+/// Leap seconds may also be used.
+///
+/// ```
+/// # use chrono::NaiveDate;
+/// let dt = NaiveDate::from_ymd_opt(2015, 6, 30).unwrap().and_hms_milli_opt(23, 59, 59, 1_500).unwrap();
+/// assert_eq!(format!("{:?}", dt), "2015-06-30T23:59:60.500");
+/// ```
+impl fmt::Debug for NaiveDateTime {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        self.date.fmt(f)?;
+        f.write_char('T')?;
+        self.time.fmt(f)
+    }
+}
+
+/// The `Display` output of the naive date and time `dt` is the same as
+/// [`dt.format("%Y-%m-%d %H:%M:%S%.f")`](crate::format::strftime).
+///
+/// It should be noted that, for leap seconds not on the minute boundary,
+/// it may print a representation not distinguishable from non-leap seconds.
+/// This doesn't matter in practice, since such leap seconds never happened.
+/// (By the time of the first leap second on 1972-06-30,
+/// every time zone offset around the world has standardized to the 5-minute alignment.)
+///
+/// # Example
+///
+/// ```
+/// use chrono::NaiveDate;
+///
+/// let dt = NaiveDate::from_ymd_opt(2016, 11, 15).unwrap().and_hms_opt(7, 39, 24).unwrap();
+/// assert_eq!(format!("{}", dt), "2016-11-15 07:39:24");
+/// ```
+///
+/// Leap seconds may also be used.
+///
+/// ```
+/// # use chrono::NaiveDate;
+/// let dt = NaiveDate::from_ymd_opt(2015, 6, 30).unwrap().and_hms_milli_opt(23, 59, 59, 1_500).unwrap();
+/// assert_eq!(format!("{}", dt), "2015-06-30 23:59:60.500");
+/// ```
+impl fmt::Display for NaiveDateTime {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        self.date.fmt(f)?;
+        f.write_char(' ')?;
+        self.time.fmt(f)
+    }
+}
+
+/// Parsing a `str` into a `NaiveDateTime` uses the same format,
+/// [`%Y-%m-%dT%H:%M:%S%.f`](crate::format::strftime), as in `Debug`.
+///
+/// # Example
+///
+/// ```
+/// use chrono::{NaiveDateTime, NaiveDate};
+///
+/// let dt = NaiveDate::from_ymd_opt(2015, 9, 18).unwrap().and_hms_opt(23, 56, 4).unwrap();
+/// assert_eq!("2015-09-18T23:56:04".parse::<NaiveDateTime>(), Ok(dt));
+///
+/// let dt = NaiveDate::from_ymd_opt(12345, 6, 7).unwrap().and_hms_milli_opt(7, 59, 59, 1_500).unwrap(); // leap second
+/// assert_eq!("+12345-6-7T7:59:60.5".parse::<NaiveDateTime>(), Ok(dt));
+///
+/// assert!("foo".parse::<NaiveDateTime>().is_err());
+/// ```
+impl str::FromStr for NaiveDateTime {
+    type Err = ParseError;
+
+    fn from_str(s: &str) -> ParseResult<NaiveDateTime> {
+        const ITEMS: &[Item<'static>] = &[
+            Item::Numeric(Numeric::Year, Pad::Zero),
+            Item::Space(""),
+            Item::Literal("-"),
+            Item::Numeric(Numeric::Month, Pad::Zero),
+            Item::Space(""),
+            Item::Literal("-"),
+            Item::Numeric(Numeric::Day, Pad::Zero),
+            Item::Space(""),
+            Item::Literal("T"), // XXX shouldn't this be case-insensitive?
+            Item::Numeric(Numeric::Hour, Pad::Zero),
+            Item::Space(""),
+            Item::Literal(":"),
+            Item::Numeric(Numeric::Minute, Pad::Zero),
+            Item::Space(""),
+            Item::Literal(":"),
+            Item::Numeric(Numeric::Second, Pad::Zero),
+            Item::Fixed(Fixed::Nanosecond),
+            Item::Space(""),
+        ];
+
+        let mut parsed = Parsed::new();
+        parse(&mut parsed, s, ITEMS.iter())?;
+        parsed.to_naive_datetime_with_offset(0)
+    }
+}
+
+/// The default value for a NaiveDateTime is one with epoch 0
+/// that is, 1st of January 1970 at 00:00:00.
+///
+/// # Example
+///
+/// ```rust
+/// use chrono::NaiveDateTime;
+///
+/// let default_date = NaiveDateTime::default();
+/// assert_eq!(default_date, NaiveDateTime::from_timestamp(0, 0));
+/// ```
+impl Default for NaiveDateTime {
+    fn default() -> Self {
+        NaiveDateTime::from_timestamp_opt(0, 0).unwrap()
+    }
+}
+
+#[cfg(all(test, any(feature = "rustc-serialize", feature = "serde")))]
+fn test_encodable_json<F, E>(to_string: F)
+where
+    F: Fn(&NaiveDateTime) -> Result<String, E>,
+    E: ::std::fmt::Debug,
+{
+    assert_eq!(
+        to_string(
+            &NaiveDate::from_ymd_opt(2016, 7, 8).unwrap().and_hms_milli_opt(9, 10, 48, 90).unwrap()
+        )
+        .ok(),
+        Some(r#""2016-07-08T09:10:48.090""#.into())
+    );
+    assert_eq!(
+        to_string(&NaiveDate::from_ymd_opt(2014, 7, 24).unwrap().and_hms_opt(12, 34, 6).unwrap())
+            .ok(),
+        Some(r#""2014-07-24T12:34:06""#.into())
+    );
+    assert_eq!(
+        to_string(
+            &NaiveDate::from_ymd_opt(0, 1, 1).unwrap().and_hms_milli_opt(0, 0, 59, 1_000).unwrap()
+        )
+        .ok(),
+        Some(r#""0000-01-01T00:00:60""#.into())
+    );
+    assert_eq!(
+        to_string(
+            &NaiveDate::from_ymd_opt(-1, 12, 31).unwrap().and_hms_nano_opt(23, 59, 59, 7).unwrap()
+        )
+        .ok(),
+        Some(r#""-0001-12-31T23:59:59.000000007""#.into())
+    );
+    assert_eq!(
+        to_string(&NaiveDate::MIN.and_hms_opt(0, 0, 0).unwrap()).ok(),
+        Some(r#""-262144-01-01T00:00:00""#.into())
+    );
+    assert_eq!(
+        to_string(&NaiveDate::MAX.and_hms_nano_opt(23, 59, 59, 1_999_999_999).unwrap()).ok(),
+        Some(r#""+262143-12-31T23:59:60.999999999""#.into())
+    );
+}
+
+#[cfg(all(test, any(feature = "rustc-serialize", feature = "serde")))]
+fn test_decodable_json<F, E>(from_str: F)
+where
+    F: Fn(&str) -> Result<NaiveDateTime, E>,
+    E: ::std::fmt::Debug,
+{
+    assert_eq!(
+        from_str(r#""2016-07-08T09:10:48.090""#).ok(),
+        Some(
+            NaiveDate::from_ymd_opt(2016, 7, 8).unwrap().and_hms_milli_opt(9, 10, 48, 90).unwrap()
+        )
+    );
+    assert_eq!(
+        from_str(r#""2016-7-8T9:10:48.09""#).ok(),
+        Some(
+            NaiveDate::from_ymd_opt(2016, 7, 8).unwrap().and_hms_milli_opt(9, 10, 48, 90).unwrap()
+        )
+    );
+    assert_eq!(
+        from_str(r#""2014-07-24T12:34:06""#).ok(),
+        Some(NaiveDate::from_ymd_opt(2014, 7, 24).unwrap().and_hms_opt(12, 34, 6).unwrap())
+    );
+    assert_eq!(
+        from_str(r#""0000-01-01T00:00:60""#).ok(),
+        Some(NaiveDate::from_ymd_opt(0, 1, 1).unwrap().and_hms_milli_opt(0, 0, 59, 1_000).unwrap())
+    );
+    assert_eq!(
+        from_str(r#""0-1-1T0:0:60""#).ok(),
+        Some(NaiveDate::from_ymd_opt(0, 1, 1).unwrap().and_hms_milli_opt(0, 0, 59, 1_000).unwrap())
+    );
+    assert_eq!(
+        from_str(r#""-0001-12-31T23:59:59.000000007""#).ok(),
+        Some(NaiveDate::from_ymd_opt(-1, 12, 31).unwrap().and_hms_nano_opt(23, 59, 59, 7).unwrap())
+    );
+    assert_eq!(
+        from_str(r#""-262144-01-01T00:00:00""#).ok(),
+        Some(NaiveDate::MIN.and_hms_opt(0, 0, 0).unwrap())
+    );
+    assert_eq!(
+        from_str(r#""+262143-12-31T23:59:60.999999999""#).ok(),
+        Some(NaiveDate::MAX.and_hms_nano_opt(23, 59, 59, 1_999_999_999).unwrap())
+    );
+    assert_eq!(
+        from_str(r#""+262143-12-31T23:59:60.9999999999997""#).ok(), // excess digits are ignored
+        Some(NaiveDate::MAX.and_hms_nano_opt(23, 59, 59, 1_999_999_999).unwrap())
+    );
+
+    // bad formats
+    assert!(from_str(r#""""#).is_err());
+    assert!(from_str(r#""2016-07-08""#).is_err());
+    assert!(from_str(r#""09:10:48.090""#).is_err());
+    assert!(from_str(r#""20160708T091048.090""#).is_err());
+    assert!(from_str(r#""2000-00-00T00:00:00""#).is_err());
+    assert!(from_str(r#""2000-02-30T00:00:00""#).is_err());
+    assert!(from_str(r#""2001-02-29T00:00:00""#).is_err());
+    assert!(from_str(r#""2002-02-28T24:00:00""#).is_err());
+    assert!(from_str(r#""2002-02-28T23:60:00""#).is_err());
+    assert!(from_str(r#""2002-02-28T23:59:61""#).is_err());
+    assert!(from_str(r#""2016-07-08T09:10:48,090""#).is_err());
+    assert!(from_str(r#""2016-07-08 09:10:48.090""#).is_err());
+    assert!(from_str(r#""2016-007-08T09:10:48.090""#).is_err());
+    assert!(from_str(r#""yyyy-mm-ddThh:mm:ss.fffffffff""#).is_err());
+    assert!(from_str(r#"20160708000000"#).is_err());
+    assert!(from_str(r#"{}"#).is_err());
+    // pre-0.3.0 rustc-serialize format is now invalid
+    assert!(from_str(r#"{"date":{"ymdf":20},"time":{"secs":0,"frac":0}}"#).is_err());
+    assert!(from_str(r#"null"#).is_err());
+}
+
+#[cfg(all(test, feature = "rustc-serialize"))]
+fn test_decodable_json_timestamp<F, E>(from_str: F)
+where
+    F: Fn(&str) -> Result<rustc_serialize::TsSeconds, E>,
+    E: ::std::fmt::Debug,
+{
+    assert_eq!(
+        *from_str("0").unwrap(),
+        NaiveDate::from_ymd_opt(1970, 1, 1).unwrap().and_hms_opt(0, 0, 0).unwrap(),
+        "should parse integers as timestamps"
+    );
+    assert_eq!(
+        *from_str("-1").unwrap(),
+        NaiveDate::from_ymd_opt(1969, 12, 31).unwrap().and_hms_opt(23, 59, 59).unwrap(),
+        "should parse integers as timestamps"
+    );
+}