1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
// This is a part of Chrono.
// See README.md and LICENSE.txt for details.

//! ISO 8601 date and time with time zone.

#[cfg(feature = "alloc")]
extern crate alloc;

#[cfg(all(not(feature = "std"), feature = "alloc"))]
use alloc::string::{String, ToString};
#[cfg(any(feature = "alloc", feature = "std", test))]
use core::borrow::Borrow;
use core::cmp::Ordering;
use core::ops::{Add, AddAssign, Sub, SubAssign};
use core::{fmt, hash, str};
#[cfg(feature = "std")]
use std::string::ToString;
#[cfg(any(feature = "std", test))]
use std::time::{SystemTime, UNIX_EPOCH};

#[cfg(any(feature = "alloc", feature = "std", test))]
use crate::format::DelayedFormat;
#[cfg(feature = "unstable-locales")]
use crate::format::Locale;
use crate::format::{parse, ParseError, ParseResult, Parsed, StrftimeItems};
use crate::format::{Fixed, Item};
use crate::naive::{IsoWeek, NaiveDate, NaiveDateTime, NaiveTime};
#[cfg(feature = "clock")]
use crate::offset::Local;
use crate::offset::{FixedOffset, Offset, TimeZone, Utc};
use crate::oldtime::Duration as OldDuration;
use crate::Date;
use crate::{Datelike, Timelike, Weekday};

#[cfg(feature = "rkyv")]
use rkyv::{Archive, Deserialize, Serialize};

#[cfg(feature = "rustc-serialize")]
pub(super) mod rustc_serialize;

/// documented at re-export site
#[cfg(feature = "serde")]
pub(super) mod serde;

#[cfg(test)]
mod tests;

/// Specific formatting options for seconds. This may be extended in the
/// future, so exhaustive matching in external code is not recommended.
///
/// See the `TimeZone::to_rfc3339_opts` function for usage.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum SecondsFormat {
    /// Format whole seconds only, with no decimal point nor subseconds.
    Secs,

    /// Use fixed 3 subsecond digits. This corresponds to
    /// [Fixed::Nanosecond3](format/enum.Fixed.html#variant.Nanosecond3).
    Millis,

    /// Use fixed 6 subsecond digits. This corresponds to
    /// [Fixed::Nanosecond6](format/enum.Fixed.html#variant.Nanosecond6).
    Micros,

    /// Use fixed 9 subsecond digits. This corresponds to
    /// [Fixed::Nanosecond9](format/enum.Fixed.html#variant.Nanosecond9).
    Nanos,

    /// Automatically select one of `Secs`, `Millis`, `Micros`, or `Nanos` to
    /// display all available non-zero sub-second digits.  This corresponds to
    /// [Fixed::Nanosecond](format/enum.Fixed.html#variant.Nanosecond).
    AutoSi,

    // Do not match against this.
    #[doc(hidden)]
    __NonExhaustive,
}

/// ISO 8601 combined date and time with time zone.
///
/// There are some constructors implemented here (the `from_*` methods), but
/// the general-purpose constructors are all via the methods on the
/// [`TimeZone`](./offset/trait.TimeZone.html) implementations.
#[derive(Clone)]
#[cfg_attr(feature = "rkyv", derive(Archive, Deserialize, Serialize))]
pub struct DateTime<Tz: TimeZone> {
    datetime: NaiveDateTime,
    offset: Tz::Offset,
}

/// The minimum possible `DateTime<Utc>`.
#[deprecated(since = "0.4.20", note = "Use DateTime::MIN_UTC instead")]
pub const MIN_DATETIME: DateTime<Utc> = DateTime::<Utc>::MIN_UTC;
/// The maximum possible `DateTime<Utc>`.
#[deprecated(since = "0.4.20", note = "Use DateTime::MAX_UTC instead")]
pub const MAX_DATETIME: DateTime<Utc> = DateTime::<Utc>::MAX_UTC;

impl<Tz: TimeZone> DateTime<Tz> {
    /// Makes a new `DateTime` with given *UTC* datetime and offset.
    /// The local datetime should be constructed via the `TimeZone` trait.
    ///
    /// # Example
    ///
    /// ```
    /// use chrono::{DateTime, TimeZone, NaiveDateTime, Utc};
    ///
    /// let dt = DateTime::<Utc>::from_utc(NaiveDateTime::from_timestamp(61, 0), Utc);
    /// assert_eq!(Utc.timestamp(61, 0), dt);
    /// ```
    //
    // note: this constructor is purposely not named to `new` to discourage the direct usage.
    #[inline]
    pub fn from_utc(datetime: NaiveDateTime, offset: Tz::Offset) -> DateTime<Tz> {
        DateTime { datetime, offset }
    }

    /// Makes a new `DateTime` with given **local** datetime and offset that
    /// presents local timezone.
    ///
    /// # Example
    ///
    /// ```
    /// use chrono::DateTime;
    /// use chrono::naive::NaiveDate;
    /// use chrono::offset::{Utc, FixedOffset};
    ///
    /// let naivedatetime_utc = NaiveDate::from_ymd(2000, 1, 12).and_hms(2, 0, 0);
    /// let datetime_utc = DateTime::<Utc>::from_utc(naivedatetime_utc, Utc);
    ///
    /// let timezone_east = FixedOffset::east(8 * 60 * 60);
    /// let naivedatetime_east = NaiveDate::from_ymd(2000, 1, 12).and_hms(10, 0, 0);
    /// let datetime_east = DateTime::<FixedOffset>::from_local(naivedatetime_east, timezone_east);
    ///
    /// let timezone_west = FixedOffset::west(7 * 60 * 60);
    /// let naivedatetime_west = NaiveDate::from_ymd(2000, 1, 11).and_hms(19, 0, 0);
    /// let datetime_west = DateTime::<FixedOffset>::from_local(naivedatetime_west, timezone_west);

    /// assert_eq!(datetime_east, datetime_utc.with_timezone(&timezone_east));
    /// assert_eq!(datetime_west, datetime_utc.with_timezone(&timezone_west));
    /// ```
    #[inline]
    pub fn from_local(datetime: NaiveDateTime, offset: Tz::Offset) -> DateTime<Tz> {
        let datetime_utc = datetime - offset.fix();

        DateTime { datetime: datetime_utc, offset }
    }

    /// Retrieves a date component
    ///
    /// Unless you are immediately planning on turning this into a `DateTime`
    /// with the same Timezone you should use the
    /// [`date_naive`](DateTime::date_naive) method.
    ///
    /// ```
    /// use chrono::prelude::*;
    ///
    /// let date: Date<Utc> = Utc.ymd(2020, 1, 1);
    /// let dt: DateTime<Utc> = date.and_hms(0, 0, 0);
    ///
    /// assert_eq!(dt.date(), date);
    ///
    /// assert_eq!(dt.date().and_hms(1, 1, 1), date.and_hms(1, 1, 1));
    /// ```
    #[inline]
    pub fn date(&self) -> Date<Tz> {
        Date::from_utc(self.naive_local().date(), self.offset.clone())
    }

    /// Retrieves the Date without an associated timezone
    ///
    /// [`NaiveDate`] is a more well-defined type, and has more traits implemented on it,
    /// so should be preferred to [`Date`] any time you truly want to operate on Dates.
    ///
    /// ```
    /// use chrono::prelude::*;
    ///
    /// let date: DateTime<Utc> = Utc.ymd(2020, 1, 1).and_hms(0, 0, 0);
    /// let other: DateTime<FixedOffset> = FixedOffset::east(23).ymd(2020, 1, 1).and_hms(0, 0, 0);
    /// assert_eq!(date.date_naive(), other.date_naive());
    /// ```
    #[inline]
    pub fn date_naive(&self) -> NaiveDate {
        let local = self.naive_local();
        NaiveDate::from_ymd(local.year(), local.month(), local.day())
    }

    /// Retrieves a time component.
    /// Unlike `date`, this is not associated to the time zone.
    #[inline]
    pub fn time(&self) -> NaiveTime {
        self.datetime.time() + self.offset.fix()
    }

    /// Returns the number of non-leap seconds since January 1, 1970 0:00:00 UTC
    /// (aka "UNIX timestamp").
    #[inline]
    pub fn timestamp(&self) -> i64 {
        self.datetime.timestamp()
    }

    /// Returns the number of non-leap-milliseconds since January 1, 1970 UTC
    ///
    /// Note 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::Utc;
    /// use chrono::TimeZone;
    ///
    /// let dt = Utc.ymd(1970, 1, 1).and_hms_milli(0, 0, 1, 444);
    /// assert_eq!(dt.timestamp_millis(), 1_444);
    ///
    /// let dt = Utc.ymd(2001, 9, 9).and_hms_milli(1, 46, 40, 555);
    /// assert_eq!(dt.timestamp_millis(), 1_000_000_000_555);
    /// ```
    #[inline]
    pub fn timestamp_millis(&self) -> i64 {
        self.datetime.timestamp_millis()
    }

    /// Returns the number of non-leap-microseconds since January 1, 1970 UTC
    ///
    /// Note 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::Utc;
    /// use chrono::TimeZone;
    ///
    /// let dt = Utc.ymd(1970, 1, 1).and_hms_micro(0, 0, 1, 444);
    /// assert_eq!(dt.timestamp_micros(), 1_000_444);
    ///
    /// let dt = Utc.ymd(2001, 9, 9).and_hms_micro(1, 46, 40, 555);
    /// assert_eq!(dt.timestamp_micros(), 1_000_000_000_000_555);
    /// ```
    #[inline]
    pub fn timestamp_micros(&self) -> i64 {
        self.datetime.timestamp_micros()
    }

    /// Returns the number of non-leap-nanoseconds since January 1, 1970 UTC
    ///
    /// Note that this does reduce the number of years that can be represented
    /// from ~584 Billion to ~584. (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::Utc;
    /// use chrono::TimeZone;
    ///
    /// let dt = Utc.ymd(1970, 1, 1).and_hms_nano(0, 0, 1, 444);
    /// assert_eq!(dt.timestamp_nanos(), 1_000_000_444);
    ///
    /// let dt = Utc.ymd(2001, 9, 9).and_hms_nano(1, 46, 40, 555);
    /// assert_eq!(dt.timestamp_nanos(), 1_000_000_000_000_000_555);
    /// ```
    #[inline]
    pub fn timestamp_nanos(&self) -> i64 {
        self.datetime.timestamp_nanos()
    }

    /// Returns the number of milliseconds since the last second boundary
    ///
    /// warning: in event of a leap second, this may exceed 999
    ///
    /// note: this is not the number of milliseconds since January 1, 1970 0:00:00 UTC
    #[inline]
    pub fn timestamp_subsec_millis(&self) -> u32 {
        self.datetime.timestamp_subsec_millis()
    }

    /// Returns the number of microseconds since the last second boundary
    ///
    /// warning: in event of a leap second, this may exceed 999_999
    ///
    /// note: this is not the number of microseconds since January 1, 1970 0:00:00 UTC
    #[inline]
    pub fn timestamp_subsec_micros(&self) -> u32 {
        self.datetime.timestamp_subsec_micros()
    }

    /// Returns the number of nanoseconds since the last second boundary
    ///
    /// warning: in event of a leap second, this may exceed 999_999_999
    ///
    /// note: this is not the number of nanoseconds since January 1, 1970 0:00:00 UTC
    #[inline]
    pub fn timestamp_subsec_nanos(&self) -> u32 {
        self.datetime.timestamp_subsec_nanos()
    }

    /// Retrieves an associated offset from UTC.
    #[inline]
    pub fn offset(&self) -> &Tz::Offset {
        &self.offset
    }

    /// Retrieves an associated time zone.
    #[inline]
    pub fn timezone(&self) -> Tz {
        TimeZone::from_offset(&self.offset)
    }

    /// Changes the associated time zone.
    /// The returned `DateTime` references the same instant of time from the perspective of the provided time zone.
    #[inline]
    pub fn with_timezone<Tz2: TimeZone>(&self, tz: &Tz2) -> DateTime<Tz2> {
        tz.from_utc_datetime(&self.datetime)
    }

    /// Adds given `Duration` to the current date and time.
    ///
    /// Returns `None` when it will result in overflow.
    #[inline]
    pub fn checked_add_signed(self, rhs: OldDuration) -> Option<DateTime<Tz>> {
        let datetime = self.datetime.checked_add_signed(rhs)?;
        let tz = self.timezone();
        Some(tz.from_utc_datetime(&datetime))
    }

    /// Subtracts given `Duration` from the current date and time.
    ///
    /// Returns `None` when it will result in overflow.
    #[inline]
    pub fn checked_sub_signed(self, rhs: OldDuration) -> Option<DateTime<Tz>> {
        let datetime = self.datetime.checked_sub_signed(rhs)?;
        let tz = self.timezone();
        Some(tz.from_utc_datetime(&datetime))
    }

    /// Subtracts another `DateTime` from the current date and time.
    /// This does not overflow or underflow at all.
    #[inline]
    pub fn signed_duration_since<Tz2: TimeZone>(self, rhs: DateTime<Tz2>) -> OldDuration {
        self.datetime.signed_duration_since(rhs.datetime)
    }

    /// Returns a view to the naive UTC datetime.
    #[inline]
    pub fn naive_utc(&self) -> NaiveDateTime {
        self.datetime
    }

    /// Returns a view to the naive local datetime.
    #[inline]
    pub fn naive_local(&self) -> NaiveDateTime {
        self.datetime + self.offset.fix()
    }

    /// Retrieve the elapsed years from now to the given [`DateTime`].
    pub fn years_since(&self, base: Self) -> Option<u32> {
        let mut years = self.year() - base.year();
        let earlier_time =
            (self.month(), self.day(), self.time()) < (base.month(), base.day(), base.time());

        years -= match earlier_time {
            true => 1,
            false => 0,
        };

        match years >= 0 {
            true => Some(years as u32),
            false => None,
        }
    }

    /// The minimum possible `DateTime<Utc>`.
    pub const MIN_UTC: DateTime<Utc> = DateTime { datetime: NaiveDateTime::MIN, offset: Utc };
    /// The maximum possible `DateTime<Utc>`.
    pub const MAX_UTC: DateTime<Utc> = DateTime { datetime: NaiveDateTime::MAX, offset: Utc };
}

impl Default for DateTime<Utc> {
    fn default() -> Self {
        Utc.from_utc_datetime(&NaiveDateTime::default())
    }
}

#[cfg(feature = "clock")]
impl Default for DateTime<Local> {
    fn default() -> Self {
        Local.from_utc_datetime(&NaiveDateTime::default())
    }
}

impl Default for DateTime<FixedOffset> {
    fn default() -> Self {
        FixedOffset::west(0).from_utc_datetime(&NaiveDateTime::default())
    }
}

/// Convert a `DateTime<Utc>` instance into a `DateTime<FixedOffset>` instance.
impl From<DateTime<Utc>> for DateTime<FixedOffset> {
    /// Convert this `DateTime<Utc>` instance into a `DateTime<FixedOffset>` instance.
    ///
    /// Conversion is done via [`DateTime::with_timezone`]. Note that the converted value returned by
    /// this will be created with a fixed timezone offset of 0.
    fn from(src: DateTime<Utc>) -> Self {
        src.with_timezone(&FixedOffset::east(0))
    }
}

/// Convert a `DateTime<Utc>` instance into a `DateTime<Local>` instance.
#[cfg(feature = "clock")]
impl From<DateTime<Utc>> for DateTime<Local> {
    /// Convert this `DateTime<Utc>` instance into a `DateTime<Local>` instance.
    ///
    /// Conversion is performed via [`DateTime::with_timezone`], accounting for the difference in timezones.
    fn from(src: DateTime<Utc>) -> Self {
        src.with_timezone(&Local)
    }
}

/// Convert a `DateTime<FixedOffset>` instance into a `DateTime<Utc>` instance.
impl From<DateTime<FixedOffset>> for DateTime<Utc> {
    /// Convert this `DateTime<FixedOffset>` instance into a `DateTime<Utc>` instance.
    ///
    /// Conversion is performed via [`DateTime::with_timezone`], accounting for the timezone
    /// difference.
    fn from(src: DateTime<FixedOffset>) -> Self {
        src.with_timezone(&Utc)
    }
}

/// Convert a `DateTime<FixedOffset>` instance into a `DateTime<Local>` instance.
#[cfg(feature = "clock")]
impl From<DateTime<FixedOffset>> for DateTime<Local> {
    /// Convert this `DateTime<FixedOffset>` instance into a `DateTime<Local>` instance.
    ///
    /// Conversion is performed via [`DateTime::with_timezone`]. Returns the equivalent value in local
    /// time.
    fn from(src: DateTime<FixedOffset>) -> Self {
        src.with_timezone(&Local)
    }
}

/// Convert a `DateTime<Local>` instance into a `DateTime<Utc>` instance.
#[cfg(feature = "clock")]
impl From<DateTime<Local>> for DateTime<Utc> {
    /// Convert this `DateTime<Local>` instance into a `DateTime<Utc>` instance.
    ///
    /// Conversion is performed via [`DateTime::with_timezone`], accounting for the difference in
    /// timezones.
    fn from(src: DateTime<Local>) -> Self {
        src.with_timezone(&Utc)
    }
}

/// Convert a `DateTime<Local>` instance into a `DateTime<FixedOffset>` instance.
#[cfg(feature = "clock")]
impl From<DateTime<Local>> for DateTime<FixedOffset> {
    /// Convert this `DateTime<Local>` instance into a `DateTime<FixedOffset>` instance.
    ///
    /// Conversion is performed via [`DateTime::with_timezone`]. Note that the converted value returned
    /// by this will be created with a fixed timezone offset of 0.
    fn from(src: DateTime<Local>) -> Self {
        src.with_timezone(&FixedOffset::east(0))
    }
}

/// Maps the local datetime to other datetime with given conversion function.
fn map_local<Tz: TimeZone, F>(dt: &DateTime<Tz>, mut f: F) -> Option<DateTime<Tz>>
where
    F: FnMut(NaiveDateTime) -> Option<NaiveDateTime>,
{
    f(dt.naive_local()).and_then(|datetime| dt.timezone().from_local_datetime(&datetime).single())
}

impl DateTime<FixedOffset> {
    /// Parses an RFC 2822 date and time string such as `Tue, 1 Jul 2003 10:52:37 +0200`,
    /// then returns a new [`DateTime`] with a parsed [`FixedOffset`].
    ///
    /// RFC 2822 is the internet message standard that specifies the
    /// representation of times in HTTP and email headers.
    ///
    /// ```
    /// # use chrono::{DateTime, FixedOffset, TimeZone};
    /// assert_eq!(
    ///     DateTime::parse_from_rfc2822("Wed, 18 Feb 2015 23:16:09 GMT").unwrap(),
    ///     FixedOffset::east(0).ymd(2015, 2, 18).and_hms(23, 16, 9)
    /// );
    /// ```
    pub fn parse_from_rfc2822(s: &str) -> ParseResult<DateTime<FixedOffset>> {
        const ITEMS: &[Item<'static>] = &[Item::Fixed(Fixed::RFC2822)];
        let mut parsed = Parsed::new();
        parse(&mut parsed, s, ITEMS.iter())?;
        parsed.to_datetime()
    }

    /// Parses an RFC 3339 and ISO 8601 date and time string such as `1996-12-19T16:39:57-08:00`,
    /// then returns a new [`DateTime`] with a parsed [`FixedOffset`].
    ///
    /// Why isn't this named `parse_from_iso8601`? That's because ISO 8601 allows some freedom
    /// over the syntax and RFC 3339 exercises that freedom to rigidly define a fixed format.
    pub fn parse_from_rfc3339(s: &str) -> ParseResult<DateTime<FixedOffset>> {
        const ITEMS: &[Item<'static>] = &[Item::Fixed(Fixed::RFC3339)];
        let mut parsed = Parsed::new();
        parse(&mut parsed, s, ITEMS.iter())?;
        parsed.to_datetime()
    }

    /// Parses a string with the specified format string and returns a new
    /// [`DateTime`] with a parsed [`FixedOffset`].
    ///
    /// See the [`crate::format::strftime`] module on the supported escape
    /// sequences.
    ///
    /// See also [`TimeZone::datetime_from_str`] which gives a local
    /// [`DateTime`] on specific time zone.
    ///
    /// Note that this method *requires a timezone* in the string. See
    /// [`NaiveDateTime::parse_from_str`]
    /// for a version that does not require a timezone in the to-be-parsed str.
    ///
    /// # Example
    ///
    /// ```rust
    /// use chrono::{DateTime, FixedOffset, TimeZone};
    ///
    /// let dt = DateTime::parse_from_str(
    ///     "1983 Apr 13 12:09:14.274 +0000", "%Y %b %d %H:%M:%S%.3f %z");
    /// assert_eq!(dt, Ok(FixedOffset::east(0).ymd(1983, 4, 13).and_hms_milli(12, 9, 14, 274)));
    /// ```
    pub fn parse_from_str(s: &str, fmt: &str) -> ParseResult<DateTime<FixedOffset>> {
        let mut parsed = Parsed::new();
        parse(&mut parsed, s, StrftimeItems::new(fmt))?;
        parsed.to_datetime()
    }
}

impl<Tz: TimeZone> DateTime<Tz>
where
    Tz::Offset: fmt::Display,
{
    /// Returns an RFC 2822 date and time string such as `Tue, 1 Jul 2003 10:52:37 +0200`.
    #[cfg(any(feature = "alloc", feature = "std", test))]
    pub fn to_rfc2822(&self) -> String {
        const ITEMS: &[Item<'static>] = &[Item::Fixed(Fixed::RFC2822)];
        self.format_with_items(ITEMS.iter()).to_string()
    }

    /// Returns an RFC 3339 and ISO 8601 date and time string such as `1996-12-19T16:39:57-08:00`.
    #[cfg(any(feature = "alloc", feature = "std", test))]
    pub fn to_rfc3339(&self) -> String {
        const ITEMS: &[Item<'static>] = &[Item::Fixed(Fixed::RFC3339)];
        self.format_with_items(ITEMS.iter()).to_string()
    }

    /// Return an RFC 3339 and ISO 8601 date and time string with subseconds
    /// formatted as per a `SecondsFormat`.
    ///
    /// If passed `use_z` true and the timezone is UTC (offset 0), use 'Z', as
    /// per [`Fixed::TimezoneOffsetColonZ`] If passed `use_z` false, use
    /// [`Fixed::TimezoneOffsetColon`]
    ///
    /// # Examples
    ///
    /// ```rust
    /// # use chrono::{DateTime, FixedOffset, SecondsFormat, TimeZone, Utc};
    /// let dt = Utc.ymd(2018, 1, 26).and_hms_micro(18, 30, 9, 453_829);
    /// assert_eq!(dt.to_rfc3339_opts(SecondsFormat::Millis, false),
    ///            "2018-01-26T18:30:09.453+00:00");
    /// assert_eq!(dt.to_rfc3339_opts(SecondsFormat::Millis, true),
    ///            "2018-01-26T18:30:09.453Z");
    /// assert_eq!(dt.to_rfc3339_opts(SecondsFormat::Secs, true),
    ///            "2018-01-26T18:30:09Z");
    ///
    /// let pst = FixedOffset::east(8 * 60 * 60);
    /// let dt = pst.ymd(2018, 1, 26).and_hms_micro(10, 30, 9, 453_829);
    /// assert_eq!(dt.to_rfc3339_opts(SecondsFormat::Secs, true),
    ///            "2018-01-26T10:30:09+08:00");
    /// ```
    #[cfg(any(feature = "alloc", feature = "std", test))]
    pub fn to_rfc3339_opts(&self, secform: SecondsFormat, use_z: bool) -> String {
        use crate::format::Numeric::*;
        use crate::format::Pad::Zero;
        use crate::SecondsFormat::*;

        debug_assert!(secform != __NonExhaustive, "Do not use __NonExhaustive!");

        const PREFIX: &[Item<'static>] = &[
            Item::Numeric(Year, Zero),
            Item::Literal("-"),
            Item::Numeric(Month, Zero),
            Item::Literal("-"),
            Item::Numeric(Day, Zero),
            Item::Literal("T"),
            Item::Numeric(Hour, Zero),
            Item::Literal(":"),
            Item::Numeric(Minute, Zero),
            Item::Literal(":"),
            Item::Numeric(Second, Zero),
        ];

        let ssitem = match secform {
            Secs => None,
            Millis => Some(Item::Fixed(Fixed::Nanosecond3)),
            Micros => Some(Item::Fixed(Fixed::Nanosecond6)),
            Nanos => Some(Item::Fixed(Fixed::Nanosecond9)),
            AutoSi => Some(Item::Fixed(Fixed::Nanosecond)),
            __NonExhaustive => unreachable!(),
        };

        let tzitem = Item::Fixed(if use_z {
            Fixed::TimezoneOffsetColonZ
        } else {
            Fixed::TimezoneOffsetColon
        });

        match ssitem {
            None => self.format_with_items(PREFIX.iter().chain([tzitem].iter())).to_string(),
            Some(s) => self.format_with_items(PREFIX.iter().chain([s, tzitem].iter())).to_string(),
        }
    }

    /// Formats the combined date and time with the specified formatting items.
    #[cfg(any(feature = "alloc", feature = "std", test))]
    #[inline]
    pub fn format_with_items<'a, I, B>(&self, items: I) -> DelayedFormat<I>
    where
        I: Iterator<Item = B> + Clone,
        B: Borrow<Item<'a>>,
    {
        let local = self.naive_local();
        DelayedFormat::new_with_offset(Some(local.date()), Some(local.time()), &self.offset, items)
    }

    /// Formats the combined date and time with the specified format string.
    /// See the [`crate::format::strftime`] module
    /// on the supported escape sequences.
    ///
    /// # Example
    /// ```rust
    /// use chrono::prelude::*;
    ///
    /// let date_time: DateTime<Utc> = Utc.ymd(2017, 04, 02).and_hms(12, 50, 32);
    /// let formatted = format!("{}", date_time.format("%d/%m/%Y %H:%M"));
    /// assert_eq!(formatted, "02/04/2017 12:50");
    /// ```
    #[cfg(any(feature = "alloc", feature = "std", test))]
    #[inline]
    pub fn format<'a>(&self, fmt: &'a str) -> DelayedFormat<StrftimeItems<'a>> {
        self.format_with_items(StrftimeItems::new(fmt))
    }

    /// Formats the combined date and time with the specified formatting items and locale.
    #[cfg(feature = "unstable-locales")]
    #[inline]
    pub fn format_localized_with_items<'a, I, B>(
        &self,
        items: I,
        locale: Locale,
    ) -> DelayedFormat<I>
    where
        I: Iterator<Item = B> + Clone,
        B: Borrow<Item<'a>>,
    {
        let local = self.naive_local();
        DelayedFormat::new_with_offset_and_locale(
            Some(local.date()),
            Some(local.time()),
            &self.offset,
            items,
            locale,
        )
    }

    /// Formats the combined date and time with the specified format string and
    /// locale.
    ///
    /// See the [`::format::strftime`] module on the supported escape
    /// sequences.
    #[cfg(feature = "unstable-locales")]
    #[inline]
    pub fn format_localized<'a>(
        &self,
        fmt: &'a str,
        locale: Locale,
    ) -> DelayedFormat<StrftimeItems<'a>> {
        self.format_localized_with_items(StrftimeItems::new_with_locale(fmt, locale), locale)
    }
}

impl<Tz: TimeZone> Datelike for DateTime<Tz> {
    #[inline]
    fn year(&self) -> i32 {
        self.naive_local().year()
    }
    #[inline]
    fn month(&self) -> u32 {
        self.naive_local().month()
    }
    #[inline]
    fn month0(&self) -> u32 {
        self.naive_local().month0()
    }
    #[inline]
    fn day(&self) -> u32 {
        self.naive_local().day()
    }
    #[inline]
    fn day0(&self) -> u32 {
        self.naive_local().day0()
    }
    #[inline]
    fn ordinal(&self) -> u32 {
        self.naive_local().ordinal()
    }
    #[inline]
    fn ordinal0(&self) -> u32 {
        self.naive_local().ordinal0()
    }
    #[inline]
    fn weekday(&self) -> Weekday {
        self.naive_local().weekday()
    }
    #[inline]
    fn iso_week(&self) -> IsoWeek {
        self.naive_local().iso_week()
    }

    #[inline]
    fn with_year(&self, year: i32) -> Option<DateTime<Tz>> {
        map_local(self, |datetime| datetime.with_year(year))
    }

    #[inline]
    fn with_month(&self, month: u32) -> Option<DateTime<Tz>> {
        map_local(self, |datetime| datetime.with_month(month))
    }

    #[inline]
    fn with_month0(&self, month0: u32) -> Option<DateTime<Tz>> {
        map_local(self, |datetime| datetime.with_month0(month0))
    }

    #[inline]
    fn with_day(&self, day: u32) -> Option<DateTime<Tz>> {
        map_local(self, |datetime| datetime.with_day(day))
    }

    #[inline]
    fn with_day0(&self, day0: u32) -> Option<DateTime<Tz>> {
        map_local(self, |datetime| datetime.with_day0(day0))
    }

    #[inline]
    fn with_ordinal(&self, ordinal: u32) -> Option<DateTime<Tz>> {
        map_local(self, |datetime| datetime.with_ordinal(ordinal))
    }

    #[inline]
    fn with_ordinal0(&self, ordinal0: u32) -> Option<DateTime<Tz>> {
        map_local(self, |datetime| datetime.with_ordinal0(ordinal0))
    }
}

impl<Tz: TimeZone> Timelike for DateTime<Tz> {
    #[inline]
    fn hour(&self) -> u32 {
        self.naive_local().hour()
    }
    #[inline]
    fn minute(&self) -> u32 {
        self.naive_local().minute()
    }
    #[inline]
    fn second(&self) -> u32 {
        self.naive_local().second()
    }
    #[inline]
    fn nanosecond(&self) -> u32 {
        self.naive_local().nanosecond()
    }

    #[inline]
    fn with_hour(&self, hour: u32) -> Option<DateTime<Tz>> {
        map_local(self, |datetime| datetime.with_hour(hour))
    }

    #[inline]
    fn with_minute(&self, min: u32) -> Option<DateTime<Tz>> {
        map_local(self, |datetime| datetime.with_minute(min))
    }

    #[inline]
    fn with_second(&self, sec: u32) -> Option<DateTime<Tz>> {
        map_local(self, |datetime| datetime.with_second(sec))
    }

    #[inline]
    fn with_nanosecond(&self, nano: u32) -> Option<DateTime<Tz>> {
        map_local(self, |datetime| datetime.with_nanosecond(nano))
    }
}

// we need them as automatic impls cannot handle associated types
impl<Tz: TimeZone> Copy for DateTime<Tz> where <Tz as TimeZone>::Offset: Copy {}
unsafe impl<Tz: TimeZone> Send for DateTime<Tz> where <Tz as TimeZone>::Offset: Send {}

impl<Tz: TimeZone, Tz2: TimeZone> PartialEq<DateTime<Tz2>> for DateTime<Tz> {
    fn eq(&self, other: &DateTime<Tz2>) -> bool {
        self.datetime == other.datetime
    }
}

impl<Tz: TimeZone> Eq for DateTime<Tz> {}

impl<Tz: TimeZone, Tz2: TimeZone> PartialOrd<DateTime<Tz2>> for DateTime<Tz> {
    /// Compare two DateTimes based on their true time, ignoring time zones
    ///
    /// # Example
    ///
    /// ```
    /// use chrono::prelude::*;
    ///
    /// let earlier = Utc.ymd(2015, 5, 15).and_hms(2, 0, 0).with_timezone(&FixedOffset::west(1 * 3600));
    /// let later   = Utc.ymd(2015, 5, 15).and_hms(3, 0, 0).with_timezone(&FixedOffset::west(5 * 3600));
    ///
    /// assert_eq!(earlier.to_string(), "2015-05-15 01:00:00 -01:00");
    /// assert_eq!(later.to_string(), "2015-05-14 22:00:00 -05:00");
    ///
    /// assert!(later > earlier);
    /// ```
    fn partial_cmp(&self, other: &DateTime<Tz2>) -> Option<Ordering> {
        self.datetime.partial_cmp(&other.datetime)
    }
}

impl<Tz: TimeZone> Ord for DateTime<Tz> {
    fn cmp(&self, other: &DateTime<Tz>) -> Ordering {
        self.datetime.cmp(&other.datetime)
    }
}

impl<Tz: TimeZone> hash::Hash for DateTime<Tz> {
    fn hash<H: hash::Hasher>(&self, state: &mut H) {
        self.datetime.hash(state)
    }
}

impl<Tz: TimeZone> Add<OldDuration> for DateTime<Tz> {
    type Output = DateTime<Tz>;

    #[inline]
    fn add(self, rhs: OldDuration) -> DateTime<Tz> {
        self.checked_add_signed(rhs).expect("`DateTime + Duration` overflowed")
    }
}

impl<Tz: TimeZone> AddAssign<OldDuration> for DateTime<Tz> {
    #[inline]
    fn add_assign(&mut self, rhs: OldDuration) {
        let datetime =
            self.datetime.checked_add_signed(rhs).expect("`DateTime + Duration` overflowed");
        let tz = self.timezone();
        *self = tz.from_utc_datetime(&datetime);
    }
}

impl<Tz: TimeZone> Sub<OldDuration> for DateTime<Tz> {
    type Output = DateTime<Tz>;

    #[inline]
    fn sub(self, rhs: OldDuration) -> DateTime<Tz> {
        self.checked_sub_signed(rhs).expect("`DateTime - Duration` overflowed")
    }
}

impl<Tz: TimeZone> SubAssign<OldDuration> for DateTime<Tz> {
    #[inline]
    fn sub_assign(&mut self, rhs: OldDuration) {
        let datetime =
            self.datetime.checked_sub_signed(rhs).expect("`DateTime - Duration` overflowed");
        let tz = self.timezone();
        *self = tz.from_utc_datetime(&datetime)
    }
}

impl<Tz: TimeZone> Sub<DateTime<Tz>> for DateTime<Tz> {
    type Output = OldDuration;

    #[inline]
    fn sub(self, rhs: DateTime<Tz>) -> OldDuration {
        self.signed_duration_since(rhs)
    }
}

impl<Tz: TimeZone> fmt::Debug for DateTime<Tz> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{:?}{:?}", self.naive_local(), self.offset)
    }
}

impl<Tz: TimeZone> fmt::Display for DateTime<Tz>
where
    Tz::Offset: fmt::Display,
{
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{} {}", self.naive_local(), self.offset)
    }
}

/// Accepts a relaxed form of RFC3339.
/// A space or a 'T' are acepted as the separator between the date and time
/// parts. Additional spaces are allowed between each component.
///
/// All of these examples are equivalent:
/// ```
/// # use chrono::{DateTime, Utc};
/// "2012-12-12T12:12:12Z".parse::<DateTime<Utc>>();
/// "2012-12-12 12:12:12Z".parse::<DateTime<Utc>>();
/// "2012-  12-12T12:  12:12Z".parse::<DateTime<Utc>>();
/// ```
impl str::FromStr for DateTime<Utc> {
    type Err = ParseError;

    fn from_str(s: &str) -> ParseResult<DateTime<Utc>> {
        s.parse::<DateTime<FixedOffset>>().map(|dt| dt.with_timezone(&Utc))
    }
}

/// Accepts a relaxed form of RFC3339.
/// A space or a 'T' are acepted as the separator between the date and time
/// parts. Additional spaces are allowed between each component.
///
/// All of these examples are equivalent:
/// ```
/// # use chrono::{DateTime, Local};
/// "2012-12-12T12:12:12Z".parse::<DateTime<Local>>();
/// "2012-12-12 12:12:12Z".parse::<DateTime<Local>>();
/// "2012-  12-12T12:  12:12Z".parse::<DateTime<Local>>();
/// ```
#[cfg(feature = "clock")]
impl str::FromStr for DateTime<Local> {
    type Err = ParseError;

    fn from_str(s: &str) -> ParseResult<DateTime<Local>> {
        s.parse::<DateTime<FixedOffset>>().map(|dt| dt.with_timezone(&Local))
    }
}

#[cfg(any(feature = "std", test))]
impl From<SystemTime> for DateTime<Utc> {
    fn from(t: SystemTime) -> DateTime<Utc> {
        let (sec, nsec) = match t.duration_since(UNIX_EPOCH) {
            Ok(dur) => (dur.as_secs() as i64, dur.subsec_nanos()),
            Err(e) => {
                // unlikely but should be handled
                let dur = e.duration();
                let (sec, nsec) = (dur.as_secs() as i64, dur.subsec_nanos());
                if nsec == 0 {
                    (-sec, 0)
                } else {
                    (-sec - 1, 1_000_000_000 - nsec)
                }
            }
        };
        Utc.timestamp(sec, nsec)
    }
}

#[cfg(feature = "clock")]
impl From<SystemTime> for DateTime<Local> {
    fn from(t: SystemTime) -> DateTime<Local> {
        DateTime::<Utc>::from(t).with_timezone(&Local)
    }
}

#[cfg(any(feature = "std", test))]
impl<Tz: TimeZone> From<DateTime<Tz>> for SystemTime {
    fn from(dt: DateTime<Tz>) -> SystemTime {
        use std::time::Duration;

        let sec = dt.timestamp();
        let nsec = dt.timestamp_subsec_nanos();
        if sec < 0 {
            // unlikely but should be handled
            UNIX_EPOCH - Duration::new(-sec as u64, 0) + Duration::new(0, nsec)
        } else {
            UNIX_EPOCH + Duration::new(sec as u64, nsec)
        }
    }
}

#[cfg(all(
    target_arch = "wasm32",
    feature = "wasmbind",
    not(any(target_os = "emscripten", target_os = "wasi"))
))]
impl From<js_sys::Date> for DateTime<Utc> {
    fn from(date: js_sys::Date) -> DateTime<Utc> {
        DateTime::<Utc>::from(&date)
    }
}

#[cfg(all(
    target_arch = "wasm32",
    feature = "wasmbind",
    not(any(target_os = "emscripten", target_os = "wasi"))
))]
impl From<&js_sys::Date> for DateTime<Utc> {
    fn from(date: &js_sys::Date) -> DateTime<Utc> {
        Utc.timestamp_millis(date.get_time() as i64)
    }
}

#[cfg(all(
    target_arch = "wasm32",
    feature = "wasmbind",
    not(any(target_os = "emscripten", target_os = "wasi"))
))]
impl From<DateTime<Utc>> for js_sys::Date {
    /// Converts a `DateTime<Utc>` to a JS `Date`. The resulting value may be lossy,
    /// any values that have a millisecond timestamp value greater/less than ±8,640,000,000,000,000
    /// (April 20, 271821 BCE ~ September 13, 275760 CE) will become invalid dates in JS.
    fn from(date: DateTime<Utc>) -> js_sys::Date {
        let js_millis = wasm_bindgen::JsValue::from_f64(date.timestamp_millis() as f64);
        js_sys::Date::new(&js_millis)
    }
}

#[test]
fn test_auto_conversion() {
    let utc_dt = Utc.ymd(2018, 9, 5).and_hms(23, 58, 0);
    let cdt_dt = FixedOffset::west(5 * 60 * 60).ymd(2018, 9, 5).and_hms(18, 58, 0);
    let utc_dt2: DateTime<Utc> = cdt_dt.into();
    assert_eq!(utc_dt, utc_dt2);
}

#[cfg(all(test, any(feature = "rustc-serialize", feature = "serde")))]
fn test_encodable_json<FUtc, FFixed, E>(to_string_utc: FUtc, to_string_fixed: FFixed)
where
    FUtc: Fn(&DateTime<Utc>) -> Result<String, E>,
    FFixed: Fn(&DateTime<FixedOffset>) -> Result<String, E>,
    E: ::core::fmt::Debug,
{
    assert_eq!(
        to_string_utc(&Utc.ymd(2014, 7, 24).and_hms(12, 34, 6)).ok(),
        Some(r#""2014-07-24T12:34:06Z""#.into())
    );

    assert_eq!(
        to_string_fixed(&FixedOffset::east(3660).ymd(2014, 7, 24).and_hms(12, 34, 6)).ok(),
        Some(r#""2014-07-24T12:34:06+01:01""#.into())
    );
    assert_eq!(
        to_string_fixed(&FixedOffset::east(3650).ymd(2014, 7, 24).and_hms(12, 34, 6)).ok(),
        Some(r#""2014-07-24T12:34:06+01:00:50""#.into())
    );
}

#[cfg(all(test, feature = "clock", any(feature = "rustc-serialize", feature = "serde")))]
fn test_decodable_json<FUtc, FFixed, FLocal, E>(
    utc_from_str: FUtc,
    fixed_from_str: FFixed,
    local_from_str: FLocal,
) where
    FUtc: Fn(&str) -> Result<DateTime<Utc>, E>,
    FFixed: Fn(&str) -> Result<DateTime<FixedOffset>, E>,
    FLocal: Fn(&str) -> Result<DateTime<Local>, E>,
    E: ::core::fmt::Debug,
{
    // should check against the offset as well (the normal DateTime comparison will ignore them)
    fn norm<Tz: TimeZone>(dt: &Option<DateTime<Tz>>) -> Option<(&DateTime<Tz>, &Tz::Offset)> {
        dt.as_ref().map(|dt| (dt, dt.offset()))
    }

    assert_eq!(
        norm(&utc_from_str(r#""2014-07-24T12:34:06Z""#).ok()),
        norm(&Some(Utc.ymd(2014, 7, 24).and_hms(12, 34, 6)))
    );
    assert_eq!(
        norm(&utc_from_str(r#""2014-07-24T13:57:06+01:23""#).ok()),
        norm(&Some(Utc.ymd(2014, 7, 24).and_hms(12, 34, 6)))
    );

    assert_eq!(
        norm(&fixed_from_str(r#""2014-07-24T12:34:06Z""#).ok()),
        norm(&Some(FixedOffset::east(0).ymd(2014, 7, 24).and_hms(12, 34, 6)))
    );
    assert_eq!(
        norm(&fixed_from_str(r#""2014-07-24T13:57:06+01:23""#).ok()),
        norm(&Some(FixedOffset::east(60 * 60 + 23 * 60).ymd(2014, 7, 24).and_hms(13, 57, 6)))
    );

    // we don't know the exact local offset but we can check that
    // the conversion didn't change the instant itself
    assert_eq!(
        local_from_str(r#""2014-07-24T12:34:06Z""#).expect("local shouuld parse"),
        Utc.ymd(2014, 7, 24).and_hms(12, 34, 6)
    );
    assert_eq!(
        local_from_str(r#""2014-07-24T13:57:06+01:23""#).expect("local should parse with offset"),
        Utc.ymd(2014, 7, 24).and_hms(12, 34, 6)
    );

    assert!(utc_from_str(r#""2014-07-32T12:34:06Z""#).is_err());
    assert!(fixed_from_str(r#""2014-07-32T12:34:06Z""#).is_err());
}

#[cfg(all(test, feature = "clock", feature = "rustc-serialize"))]
fn test_decodable_json_timestamps<FUtc, FFixed, FLocal, E>(
    utc_from_str: FUtc,
    fixed_from_str: FFixed,
    local_from_str: FLocal,
) where
    FUtc: Fn(&str) -> Result<rustc_serialize::TsSeconds<Utc>, E>,
    FFixed: Fn(&str) -> Result<rustc_serialize::TsSeconds<FixedOffset>, E>,
    FLocal: Fn(&str) -> Result<rustc_serialize::TsSeconds<Local>, E>,
    E: ::core::fmt::Debug,
{
    fn norm<Tz: TimeZone>(dt: &Option<DateTime<Tz>>) -> Option<(&DateTime<Tz>, &Tz::Offset)> {
        dt.as_ref().map(|dt| (dt, dt.offset()))
    }

    assert_eq!(
        norm(&utc_from_str("0").ok().map(DateTime::from)),
        norm(&Some(Utc.ymd(1970, 1, 1).and_hms(0, 0, 0)))
    );
    assert_eq!(
        norm(&utc_from_str("-1").ok().map(DateTime::from)),
        norm(&Some(Utc.ymd(1969, 12, 31).and_hms(23, 59, 59)))
    );

    assert_eq!(
        norm(&fixed_from_str("0").ok().map(DateTime::from)),
        norm(&Some(FixedOffset::east(0).ymd(1970, 1, 1).and_hms(0, 0, 0)))
    );
    assert_eq!(
        norm(&fixed_from_str("-1").ok().map(DateTime::from)),
        norm(&Some(FixedOffset::east(0).ymd(1969, 12, 31).and_hms(23, 59, 59)))
    );

    assert_eq!(
        *fixed_from_str("0").expect("0 timestamp should parse"),
        Utc.ymd(1970, 1, 1).and_hms(0, 0, 0)
    );
    assert_eq!(
        *local_from_str("-1").expect("-1 timestamp should parse"),
        Utc.ymd(1969, 12, 31).and_hms(23, 59, 59)
    );
}