chrono/offset/local/
mod.rs

1// This is a part of Chrono.
2// See README.md and LICENSE.txt for details.
3
4//! The local (system) time zone.
5
6#[cfg(windows)]
7use std::cmp::Ordering;
8
9#[cfg(any(feature = "rkyv", feature = "rkyv-16", feature = "rkyv-32", feature = "rkyv-64"))]
10use rkyv::{Archive, Deserialize, Serialize};
11
12use super::fixed::FixedOffset;
13use super::{MappedLocalTime, TimeZone};
14#[allow(deprecated)]
15use crate::Date;
16use crate::naive::{NaiveDate, NaiveDateTime, NaiveTime};
17use crate::{DateTime, Utc};
18
19#[cfg(unix)]
20#[path = "unix.rs"]
21mod inner;
22
23#[cfg(windows)]
24#[path = "windows.rs"]
25mod inner;
26
27#[cfg(all(windows, feature = "clock"))]
28#[allow(unreachable_pub)]
29mod win_bindings;
30
31#[cfg(all(any(target_os = "android", target_env = "ohos", test), feature = "clock"))]
32mod tz_data;
33
34#[cfg(all(
35    not(unix),
36    not(windows),
37    not(all(
38        target_arch = "wasm32",
39        feature = "wasmbind",
40        not(any(target_os = "emscripten", target_os = "wasi"))
41    ))
42))]
43mod inner {
44    use crate::{FixedOffset, MappedLocalTime, NaiveDateTime};
45
46    pub(super) fn offset_from_utc_datetime(
47        _utc_time: &NaiveDateTime,
48    ) -> MappedLocalTime<FixedOffset> {
49        MappedLocalTime::Single(FixedOffset::east_opt(0).unwrap())
50    }
51
52    pub(super) fn offset_from_local_datetime(
53        _local_time: &NaiveDateTime,
54    ) -> MappedLocalTime<FixedOffset> {
55        MappedLocalTime::Single(FixedOffset::east_opt(0).unwrap())
56    }
57}
58
59#[cfg(all(
60    target_arch = "wasm32",
61    feature = "wasmbind",
62    not(any(target_os = "emscripten", target_os = "wasi", target_os = "linux"))
63))]
64mod inner {
65    use crate::{Datelike, FixedOffset, MappedLocalTime, NaiveDateTime, Timelike};
66
67    pub(super) fn offset_from_utc_datetime(utc: &NaiveDateTime) -> MappedLocalTime<FixedOffset> {
68        let offset = js_sys::Date::from(utc.and_utc()).get_timezone_offset();
69        MappedLocalTime::Single(FixedOffset::west_opt((offset as i32) * 60).unwrap())
70    }
71
72    pub(super) fn offset_from_local_datetime(
73        local: &NaiveDateTime,
74    ) -> MappedLocalTime<FixedOffset> {
75        let mut year = local.year();
76        if year < 100 {
77            // The API in `js_sys` does not let us create a `Date` with negative years.
78            // And values for years from `0` to `99` map to the years `1900` to `1999`.
79            // Shift the value by a multiple of 400 years until it is `>= 100`.
80            let shift_cycles = (year - 100).div_euclid(400);
81            year -= shift_cycles * 400;
82        }
83        let js_date = js_sys::Date::new_with_year_month_day_hr_min_sec(
84            year as u32,
85            local.month0() as i32,
86            local.day() as i32,
87            local.hour() as i32,
88            local.minute() as i32,
89            local.second() as i32,
90            // ignore milliseconds, our representation of leap seconds may be problematic
91        );
92        let offset = js_date.get_timezone_offset();
93        // We always get a result, even if this time does not exist or is ambiguous.
94        MappedLocalTime::Single(FixedOffset::west_opt((offset as i32) * 60).unwrap())
95    }
96}
97
98#[cfg(unix)]
99mod tz_info;
100
101/// The local timescale.
102///
103/// Using the [`TimeZone`](./trait.TimeZone.html) methods
104/// on the Local struct is the preferred way to construct `DateTime<Local>`
105/// instances.
106///
107/// # Example
108///
109/// ```
110/// use chrono::{DateTime, Local, TimeZone};
111///
112/// let dt1: DateTime<Local> = Local::now();
113/// let dt2: DateTime<Local> = Local.timestamp_opt(0, 0).unwrap();
114/// assert!(dt1 >= dt2);
115/// ```
116#[derive(Copy, Clone, Debug)]
117#[cfg_attr(
118    any(feature = "rkyv", feature = "rkyv-16", feature = "rkyv-32", feature = "rkyv-64"),
119    derive(Archive, Deserialize, Serialize),
120    archive(compare(PartialEq)),
121    archive_attr(derive(Clone, Copy, Debug))
122)]
123#[cfg_attr(feature = "rkyv-validation", archive(check_bytes))]
124#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
125#[cfg_attr(feature = "defmt", derive(defmt::Format))]
126pub struct Local;
127
128impl Local {
129    /// Returns a `Date` which corresponds to the current date.
130    #[deprecated(since = "0.4.23", note = "use `Local::now()` instead")]
131    #[allow(deprecated)]
132    #[must_use]
133    pub fn today() -> Date<Local> {
134        Local::now().date()
135    }
136
137    /// Returns a `DateTime<Local>` which corresponds to the current date, time and offset from
138    /// UTC.
139    ///
140    /// See also the similar [`Utc::now()`] which returns `DateTime<Utc>`, i.e. without the local
141    /// offset.
142    ///
143    /// # Example
144    ///
145    /// ```
146    /// # #![allow(unused_variables)]
147    /// # use chrono::{DateTime, FixedOffset, Local};
148    /// // Current local time
149    /// let now = Local::now();
150    ///
151    /// // Current local date
152    /// let today = now.date_naive();
153    ///
154    /// // Current local time, converted to `DateTime<FixedOffset>`
155    /// let now_fixed_offset = Local::now().fixed_offset();
156    /// // or
157    /// let now_fixed_offset: DateTime<FixedOffset> = Local::now().into();
158    ///
159    /// // Current time in some timezone (let's use +05:00)
160    /// // Note that it is usually more efficient to use `Utc::now` for this use case.
161    /// let offset = FixedOffset::east_opt(5 * 60 * 60).unwrap();
162    /// let now_with_offset = Local::now().with_timezone(&offset);
163    /// ```
164    pub fn now() -> DateTime<Local> {
165        Utc::now().with_timezone(&Local)
166    }
167}
168
169impl TimeZone for Local {
170    type Offset = FixedOffset;
171
172    fn from_offset(_offset: &FixedOffset) -> Local {
173        Local
174    }
175
176    #[allow(deprecated)]
177    fn offset_from_local_date(&self, local: &NaiveDate) -> MappedLocalTime<FixedOffset> {
178        // Get the offset at local midnight.
179        self.offset_from_local_datetime(&local.and_time(NaiveTime::MIN))
180    }
181
182    fn offset_from_local_datetime(&self, local: &NaiveDateTime) -> MappedLocalTime<FixedOffset> {
183        inner::offset_from_local_datetime(local)
184    }
185
186    #[allow(deprecated)]
187    fn offset_from_utc_date(&self, utc: &NaiveDate) -> FixedOffset {
188        // Get the offset at midnight.
189        self.offset_from_utc_datetime(&utc.and_time(NaiveTime::MIN))
190    }
191
192    fn offset_from_utc_datetime(&self, utc: &NaiveDateTime) -> FixedOffset {
193        inner::offset_from_utc_datetime(utc).unwrap()
194    }
195}
196
197#[cfg(windows)]
198#[derive(Copy, Clone, Eq, PartialEq)]
199struct Transition {
200    transition_utc: NaiveDateTime,
201    offset_before: FixedOffset,
202    offset_after: FixedOffset,
203}
204
205#[cfg(windows)]
206impl Transition {
207    fn new(
208        transition_local: NaiveDateTime,
209        offset_before: FixedOffset,
210        offset_after: FixedOffset,
211    ) -> Transition {
212        // It is no problem if the transition time in UTC falls a couple of hours inside the buffer
213        // space around the `NaiveDateTime` range (although it is very theoretical to have a
214        // transition at midnight around `NaiveDate::(MIN|MAX)`.
215        let transition_utc = transition_local.overflowing_sub_offset(offset_before);
216        Transition { transition_utc, offset_before, offset_after }
217    }
218}
219
220#[cfg(windows)]
221impl PartialOrd for Transition {
222    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
223        Some(self.cmp(other))
224    }
225}
226
227#[cfg(windows)]
228impl Ord for Transition {
229    fn cmp(&self, other: &Self) -> Ordering {
230        self.transition_utc.cmp(&other.transition_utc)
231    }
232}
233
234// Calculate the time in UTC given a local time and transitions.
235// `transitions` must be sorted.
236#[cfg(windows)]
237fn lookup_with_dst_transitions(
238    transitions: &[Transition],
239    dt: NaiveDateTime,
240) -> MappedLocalTime<FixedOffset> {
241    for t in transitions.iter() {
242        // A transition can result in the wall clock time going forward (creating a gap) or going
243        // backward (creating a fold). We are interested in the earliest and latest wall time of the
244        // transition, as this are the times between which `dt` does may not exist or is ambiguous.
245        //
246        // It is no problem if the transition times falls a couple of hours inside the buffer
247        // space around the `NaiveDateTime` range (although it is very theoretical to have a
248        // transition at midnight around `NaiveDate::(MIN|MAX)`.
249        let (offset_min, offset_max) =
250            match t.offset_after.local_minus_utc() > t.offset_before.local_minus_utc() {
251                true => (t.offset_before, t.offset_after),
252                false => (t.offset_after, t.offset_before),
253            };
254        let wall_earliest = t.transition_utc.overflowing_add_offset(offset_min);
255        let wall_latest = t.transition_utc.overflowing_add_offset(offset_max);
256
257        if dt < wall_earliest {
258            return MappedLocalTime::Single(t.offset_before);
259        } else if dt <= wall_latest {
260            return match t.offset_after.local_minus_utc().cmp(&t.offset_before.local_minus_utc()) {
261                Ordering::Equal => MappedLocalTime::Single(t.offset_before),
262                Ordering::Less => MappedLocalTime::Ambiguous(t.offset_before, t.offset_after),
263                Ordering::Greater => {
264                    if dt == wall_earliest {
265                        MappedLocalTime::Single(t.offset_before)
266                    } else if dt == wall_latest {
267                        MappedLocalTime::Single(t.offset_after)
268                    } else {
269                        MappedLocalTime::None
270                    }
271                }
272            };
273        }
274    }
275    MappedLocalTime::Single(transitions.last().unwrap().offset_after)
276}
277
278#[cfg(test)]
279mod tests {
280    use super::Local;
281    use crate::offset::TimeZone;
282    #[cfg(windows)]
283    use crate::offset::local::{Transition, lookup_with_dst_transitions};
284    use crate::{Datelike, Days, Utc};
285    #[cfg(windows)]
286    use crate::{FixedOffset, MappedLocalTime, NaiveDate, NaiveDateTime};
287
288    #[test]
289    fn verify_correct_offsets() {
290        let now = Local::now();
291        let from_local = Local.from_local_datetime(&now.naive_local()).unwrap();
292        let from_utc = Local.from_utc_datetime(&now.naive_utc());
293
294        assert_eq!(now.offset().local_minus_utc(), from_local.offset().local_minus_utc());
295        assert_eq!(now.offset().local_minus_utc(), from_utc.offset().local_minus_utc());
296
297        assert_eq!(now, from_local);
298        assert_eq!(now, from_utc);
299    }
300
301    #[test]
302    fn verify_correct_offsets_distant_past() {
303        let distant_past = Local::now() - Days::new(365 * 500);
304        let from_local = Local.from_local_datetime(&distant_past.naive_local()).unwrap();
305        let from_utc = Local.from_utc_datetime(&distant_past.naive_utc());
306
307        assert_eq!(distant_past.offset().local_minus_utc(), from_local.offset().local_minus_utc());
308        assert_eq!(distant_past.offset().local_minus_utc(), from_utc.offset().local_minus_utc());
309
310        assert_eq!(distant_past, from_local);
311        assert_eq!(distant_past, from_utc);
312    }
313
314    #[test]
315    fn verify_correct_offsets_distant_future() {
316        let distant_future = Local::now() + Days::new(365 * 35000);
317        let from_local = Local.from_local_datetime(&distant_future.naive_local()).unwrap();
318        let from_utc = Local.from_utc_datetime(&distant_future.naive_utc());
319
320        assert_eq!(
321            distant_future.offset().local_minus_utc(),
322            from_local.offset().local_minus_utc()
323        );
324        assert_eq!(distant_future.offset().local_minus_utc(), from_utc.offset().local_minus_utc());
325
326        assert_eq!(distant_future, from_local);
327        assert_eq!(distant_future, from_utc);
328    }
329
330    #[test]
331    fn test_local_date_sanity_check() {
332        // issue #27
333        assert_eq!(Local.with_ymd_and_hms(2999, 12, 28, 0, 0, 0).unwrap().day(), 28);
334    }
335
336    #[test]
337    fn test_leap_second() {
338        // issue #123
339        let today = Utc::now().date_naive();
340
341        if let Some(dt) = today.and_hms_milli_opt(15, 2, 59, 1000) {
342            let timestr = dt.time().to_string();
343            // the OS API may or may not support the leap second,
344            // but there are only two sensible options.
345            assert!(
346                timestr == "15:02:60" || timestr == "15:03:00",
347                "unexpected timestr {timestr:?}"
348            );
349        }
350
351        if let Some(dt) = today.and_hms_milli_opt(15, 2, 3, 1234) {
352            let timestr = dt.time().to_string();
353            assert!(
354                timestr == "15:02:03.234" || timestr == "15:02:04.234",
355                "unexpected timestr {timestr:?}"
356            );
357        }
358    }
359
360    #[test]
361    #[cfg(windows)]
362    fn test_lookup_with_dst_transitions() {
363        let ymdhms = |y, m, d, h, n, s| {
364            NaiveDate::from_ymd_opt(y, m, d).unwrap().and_hms_opt(h, n, s).unwrap()
365        };
366
367        #[track_caller]
368        #[allow(clippy::too_many_arguments)]
369        fn compare_lookup(
370            transitions: &[Transition],
371            y: i32,
372            m: u32,
373            d: u32,
374            h: u32,
375            n: u32,
376            s: u32,
377            result: MappedLocalTime<FixedOffset>,
378        ) {
379            let dt = NaiveDate::from_ymd_opt(y, m, d).unwrap().and_hms_opt(h, n, s).unwrap();
380            assert_eq!(lookup_with_dst_transitions(transitions, dt), result);
381        }
382
383        // dst transition before std transition
384        // dst offset > std offset
385        let std = FixedOffset::east_opt(3 * 60 * 60).unwrap();
386        let dst = FixedOffset::east_opt(4 * 60 * 60).unwrap();
387        let transitions = [
388            Transition::new(ymdhms(2023, 3, 26, 2, 0, 0), std, dst),
389            Transition::new(ymdhms(2023, 10, 29, 3, 0, 0), dst, std),
390        ];
391        compare_lookup(&transitions, 2023, 3, 26, 1, 0, 0, MappedLocalTime::Single(std));
392        compare_lookup(&transitions, 2023, 3, 26, 2, 0, 0, MappedLocalTime::Single(std));
393        compare_lookup(&transitions, 2023, 3, 26, 2, 30, 0, MappedLocalTime::None);
394        compare_lookup(&transitions, 2023, 3, 26, 3, 0, 0, MappedLocalTime::Single(dst));
395        compare_lookup(&transitions, 2023, 3, 26, 4, 0, 0, MappedLocalTime::Single(dst));
396
397        compare_lookup(&transitions, 2023, 10, 29, 1, 0, 0, MappedLocalTime::Single(dst));
398        compare_lookup(&transitions, 2023, 10, 29, 2, 0, 0, MappedLocalTime::Ambiguous(dst, std));
399        compare_lookup(&transitions, 2023, 10, 29, 2, 30, 0, MappedLocalTime::Ambiguous(dst, std));
400        compare_lookup(&transitions, 2023, 10, 29, 3, 0, 0, MappedLocalTime::Ambiguous(dst, std));
401        compare_lookup(&transitions, 2023, 10, 29, 4, 0, 0, MappedLocalTime::Single(std));
402
403        // std transition before dst transition
404        // dst offset > std offset
405        let std = FixedOffset::east_opt(-5 * 60 * 60).unwrap();
406        let dst = FixedOffset::east_opt(-4 * 60 * 60).unwrap();
407        let transitions = [
408            Transition::new(ymdhms(2023, 3, 24, 3, 0, 0), dst, std),
409            Transition::new(ymdhms(2023, 10, 27, 2, 0, 0), std, dst),
410        ];
411        compare_lookup(&transitions, 2023, 3, 24, 1, 0, 0, MappedLocalTime::Single(dst));
412        compare_lookup(&transitions, 2023, 3, 24, 2, 0, 0, MappedLocalTime::Ambiguous(dst, std));
413        compare_lookup(&transitions, 2023, 3, 24, 2, 30, 0, MappedLocalTime::Ambiguous(dst, std));
414        compare_lookup(&transitions, 2023, 3, 24, 3, 0, 0, MappedLocalTime::Ambiguous(dst, std));
415        compare_lookup(&transitions, 2023, 3, 24, 4, 0, 0, MappedLocalTime::Single(std));
416
417        compare_lookup(&transitions, 2023, 10, 27, 1, 0, 0, MappedLocalTime::Single(std));
418        compare_lookup(&transitions, 2023, 10, 27, 2, 0, 0, MappedLocalTime::Single(std));
419        compare_lookup(&transitions, 2023, 10, 27, 2, 30, 0, MappedLocalTime::None);
420        compare_lookup(&transitions, 2023, 10, 27, 3, 0, 0, MappedLocalTime::Single(dst));
421        compare_lookup(&transitions, 2023, 10, 27, 4, 0, 0, MappedLocalTime::Single(dst));
422
423        // dst transition before std transition
424        // dst offset < std offset
425        let std = FixedOffset::east_opt(3 * 60 * 60).unwrap();
426        let dst = FixedOffset::east_opt((2 * 60 + 30) * 60).unwrap();
427        let transitions = [
428            Transition::new(ymdhms(2023, 3, 26, 2, 30, 0), std, dst),
429            Transition::new(ymdhms(2023, 10, 29, 2, 0, 0), dst, std),
430        ];
431        compare_lookup(&transitions, 2023, 3, 26, 1, 0, 0, MappedLocalTime::Single(std));
432        compare_lookup(&transitions, 2023, 3, 26, 2, 0, 0, MappedLocalTime::Ambiguous(std, dst));
433        compare_lookup(&transitions, 2023, 3, 26, 2, 15, 0, MappedLocalTime::Ambiguous(std, dst));
434        compare_lookup(&transitions, 2023, 3, 26, 2, 30, 0, MappedLocalTime::Ambiguous(std, dst));
435        compare_lookup(&transitions, 2023, 3, 26, 3, 0, 0, MappedLocalTime::Single(dst));
436
437        compare_lookup(&transitions, 2023, 10, 29, 1, 0, 0, MappedLocalTime::Single(dst));
438        compare_lookup(&transitions, 2023, 10, 29, 2, 0, 0, MappedLocalTime::Single(dst));
439        compare_lookup(&transitions, 2023, 10, 29, 2, 15, 0, MappedLocalTime::None);
440        compare_lookup(&transitions, 2023, 10, 29, 2, 30, 0, MappedLocalTime::Single(std));
441        compare_lookup(&transitions, 2023, 10, 29, 3, 0, 0, MappedLocalTime::Single(std));
442
443        // std transition before dst transition
444        // dst offset < std offset
445        let std = FixedOffset::east_opt(-(4 * 60 + 30) * 60).unwrap();
446        let dst = FixedOffset::east_opt(-5 * 60 * 60).unwrap();
447        let transitions = [
448            Transition::new(ymdhms(2023, 3, 24, 2, 0, 0), dst, std),
449            Transition::new(ymdhms(2023, 10, 27, 2, 30, 0), std, dst),
450        ];
451        compare_lookup(&transitions, 2023, 3, 24, 1, 0, 0, MappedLocalTime::Single(dst));
452        compare_lookup(&transitions, 2023, 3, 24, 2, 0, 0, MappedLocalTime::Single(dst));
453        compare_lookup(&transitions, 2023, 3, 24, 2, 15, 0, MappedLocalTime::None);
454        compare_lookup(&transitions, 2023, 3, 24, 2, 30, 0, MappedLocalTime::Single(std));
455        compare_lookup(&transitions, 2023, 3, 24, 3, 0, 0, MappedLocalTime::Single(std));
456
457        compare_lookup(&transitions, 2023, 10, 27, 1, 0, 0, MappedLocalTime::Single(std));
458        compare_lookup(&transitions, 2023, 10, 27, 2, 0, 0, MappedLocalTime::Ambiguous(std, dst));
459        compare_lookup(&transitions, 2023, 10, 27, 2, 15, 0, MappedLocalTime::Ambiguous(std, dst));
460        compare_lookup(&transitions, 2023, 10, 27, 2, 30, 0, MappedLocalTime::Ambiguous(std, dst));
461        compare_lookup(&transitions, 2023, 10, 27, 3, 0, 0, MappedLocalTime::Single(dst));
462
463        // offset stays the same
464        let std = FixedOffset::east_opt(3 * 60 * 60).unwrap();
465        let transitions = [
466            Transition::new(ymdhms(2023, 3, 26, 2, 0, 0), std, std),
467            Transition::new(ymdhms(2023, 10, 29, 3, 0, 0), std, std),
468        ];
469        compare_lookup(&transitions, 2023, 3, 26, 2, 0, 0, MappedLocalTime::Single(std));
470        compare_lookup(&transitions, 2023, 10, 29, 3, 0, 0, MappedLocalTime::Single(std));
471
472        // single transition
473        let std = FixedOffset::east_opt(3 * 60 * 60).unwrap();
474        let dst = FixedOffset::east_opt(4 * 60 * 60).unwrap();
475        let transitions = [Transition::new(ymdhms(2023, 3, 26, 2, 0, 0), std, dst)];
476        compare_lookup(&transitions, 2023, 3, 26, 1, 0, 0, MappedLocalTime::Single(std));
477        compare_lookup(&transitions, 2023, 3, 26, 2, 0, 0, MappedLocalTime::Single(std));
478        compare_lookup(&transitions, 2023, 3, 26, 2, 30, 0, MappedLocalTime::None);
479        compare_lookup(&transitions, 2023, 3, 26, 3, 0, 0, MappedLocalTime::Single(dst));
480        compare_lookup(&transitions, 2023, 3, 26, 4, 0, 0, MappedLocalTime::Single(dst));
481    }
482
483    #[test]
484    #[cfg(windows)]
485    fn test_lookup_with_dst_transitions_limits() {
486        // Transition beyond UTC year end doesn't panic in year of `NaiveDate::MAX`
487        let std = FixedOffset::east_opt(3 * 60 * 60).unwrap();
488        let dst = FixedOffset::east_opt(4 * 60 * 60).unwrap();
489        let transitions = [
490            Transition::new(NaiveDateTime::MAX.with_month(7).unwrap(), std, dst),
491            Transition::new(NaiveDateTime::MAX, dst, std),
492        ];
493        assert_eq!(
494            lookup_with_dst_transitions(&transitions, NaiveDateTime::MAX.with_month(3).unwrap()),
495            MappedLocalTime::Single(std)
496        );
497        assert_eq!(
498            lookup_with_dst_transitions(&transitions, NaiveDateTime::MAX.with_month(8).unwrap()),
499            MappedLocalTime::Single(dst)
500        );
501        // Doesn't panic with `NaiveDateTime::MAX` as argument (which would be out of range when
502        // converted to UTC).
503        assert_eq!(
504            lookup_with_dst_transitions(&transitions, NaiveDateTime::MAX),
505            MappedLocalTime::Ambiguous(dst, std)
506        );
507
508        // Transition before UTC year end doesn't panic in year of `NaiveDate::MIN`
509        let std = FixedOffset::west_opt(3 * 60 * 60).unwrap();
510        let dst = FixedOffset::west_opt(4 * 60 * 60).unwrap();
511        let transitions = [
512            Transition::new(NaiveDateTime::MIN, std, dst),
513            Transition::new(NaiveDateTime::MIN.with_month(6).unwrap(), dst, std),
514        ];
515        assert_eq!(
516            lookup_with_dst_transitions(&transitions, NaiveDateTime::MIN.with_month(3).unwrap()),
517            MappedLocalTime::Single(dst)
518        );
519        assert_eq!(
520            lookup_with_dst_transitions(&transitions, NaiveDateTime::MIN.with_month(8).unwrap()),
521            MappedLocalTime::Single(std)
522        );
523        // Doesn't panic with `NaiveDateTime::MIN` as argument (which would be out of range when
524        // converted to UTC).
525        assert_eq!(
526            lookup_with_dst_transitions(&transitions, NaiveDateTime::MIN),
527            MappedLocalTime::Ambiguous(std, dst)
528        );
529    }
530
531    #[test]
532    #[cfg(feature = "rkyv-validation")]
533    fn test_rkyv_validation() {
534        let local = Local;
535        // Local is a ZST and serializes to 0 bytes
536        let bytes = rkyv::to_bytes::<_, 0>(&local).unwrap();
537        assert_eq!(bytes.len(), 0);
538
539        // but is deserialized to an archived variant without a
540        // wrapping object
541        assert_eq!(rkyv::from_bytes::<Local>(&bytes).unwrap(), super::ArchivedLocal);
542    }
543}