Fix DateTime<Local> with NaiveDateTime::{MAX, MAX}

src/offset/local/mod.rs

@@ -291,7 +291,7 @@ mod tests {
     use super::Local;
     use crate::offset::local::TzInfo;
     use crate::offset::TimeZone;
-    use crate::{Datelike, Duration, FixedOffset, LocalResult, NaiveDate, Utc};
+    use crate::{Datelike, Duration, FixedOffset, LocalResult, NaiveDate, NaiveDateTime, Utc};
 
     #[test]
     fn verify_correct_offsets() {
@@ -342,6 +342,21 @@ mod tests {
         assert_eq!(Local.with_ymd_and_hms(2999, 12, 28, 0, 0, 0).unwrap().day(), 28);
     }
 
+    #[test]
+    fn test_local_min_max_dates() {
+        let local_max = Local.from_utc_datetime(&NaiveDateTime::MAX);
+        assert_eq!(local_max.naive_utc(), NaiveDateTime::MAX);
+        let local_min = Local.from_utc_datetime(&NaiveDateTime::MIN);
+        assert_eq!(local_min.naive_utc(), NaiveDateTime::MIN);
+
+        if let Some(local_max) = Local.from_local_datetime(&NaiveDateTime::MAX).single() {
+            assert_eq!(local_max.naive_local(), NaiveDateTime::MAX);
+        }
+        if let Some(local_min) = Local.from_local_datetime(&NaiveDateTime::MIN).single() {
+            assert_eq!(local_min.naive_local(), NaiveDateTime::MIN);
+        }
+    }
+
     #[test]
     fn test_leap_second() {
         // issue #123

src/offset/local/unix.rs

@@ -12,6 +12,7 @@ use std::{cell::RefCell, collections::hash_map, env, fs, hash::Hasher, time::Sys
 
 use super::tz_info::TimeZone;
 use super::{DateTime, Local, NaiveDateTime};
+use crate::offset::local_time_min_offset;
 use crate::{Datelike, LocalResult};
 
 pub(super) fn naive_to_local(d: &NaiveDateTime, local: bool) -> LocalResult<DateTime<Local>> {
@@ -152,9 +153,10 @@ impl Cache {
 
         // we pass through the year as the year of a local point in time must either be valid in that locale, or
         // the entire time was skipped in which case we will return LocalResult::None anyway.
-        self.zone
+        let local_result_offset = self
+            .zone
             .find_local_offset_from_local(d.timestamp(), d.year())
-            .expect("unable to select local time type")
-            .map(|offset| DateTime::from_utc(d - offset, offset))
+            .expect("unable to select local time type");
+        local_time_min_offset(local_result_offset, &d).unwrap_or(LocalResult::None)
     }
 }

src/offset/local/windows.rs

@@ -16,7 +16,10 @@ use winapi::um::minwinbase::SYSTEMTIME;
 use winapi::um::timezoneapi::{GetTimeZoneInformationForYear, TIME_ZONE_INFORMATION};
 
 use super::{FixedOffset, Local, TzInfo};
-use crate::{DateTime, Datelike, LocalResult, NaiveDate, NaiveDateTime, NaiveTime, Weekday};
+use crate::offset::local_time_min_offset;
+use crate::{
+    DateTime, Datelike, Duration, LocalResult, NaiveDate, NaiveDateTime, NaiveTime, Weekday,
+};
 
 pub(super) fn naive_to_local(d: &NaiveDateTime, local: bool) -> LocalResult<DateTime<Local>> {
     let tz_info = match TzInfo::get_current_for_year(d.year()) {
@@ -95,7 +98,7 @@ impl TzInfo {
             (Some(_), Some(_)) => self.lookup_with_dst_transitions(local_time),
             _ => LocalResult::Single(self.std_offset),
         };
-        local_result_offset.map(|offset| DateTime::from_utc(*local_time - offset, offset))
+        local_time_min_offset(local_result_offset, local_time).unwrap_or(LocalResult::None)
     }
 }
 

src/offset/mod.rs

@@ -24,7 +24,7 @@ use crate::format::{parse, ParseResult, Parsed, StrftimeItems};
 use crate::naive::{NaiveDate, NaiveDateTime, NaiveTime};
 use crate::Weekday;
 #[allow(deprecated)]
-use crate::{Date, DateTime};
+use crate::{Date, DateTime, Duration, Timelike};
 
 mod fixed;
 pub use self::fixed::FixedOffset;
@@ -472,8 +472,8 @@ pub trait TimeZone: Sized + Clone {
     /// Converts the local `NaiveDateTime` to the timezone-aware `DateTime` if possible.
     #[allow(clippy::wrong_self_convention)]
     fn from_local_datetime(&self, local: &NaiveDateTime) -> LocalResult<DateTime<Self>> {
-        self.offset_from_local_datetime(local)
-            .map(|offset| DateTime::from_utc(*local - offset.fix(), offset))
+        let local_result_offset = self.offset_from_local_datetime(local);
+        local_time_min_offset(local_result_offset, local).unwrap_or(LocalResult::None)
     }
 
     /// Creates the offset for given UTC `NaiveDate`. This cannot fail.
@@ -499,10 +499,65 @@ pub trait TimeZone: Sized + Clone {
     }
 }
 
+/// Helper function to map `LocalResult<FixedOffset>` to `LocalResult<DateTime<Local>>`.
+/// Returns `None` on out-of-range.
+#[allow(dead_code)]
+pub(crate) fn local_time_min_offset<Tz: TimeZone>(
+    local_result: LocalResult<Tz::Offset>,
+    local_time: &NaiveDateTime,
+) -> Option<LocalResult<DateTime<Tz>>> {
+    // We temporarily extract and  later add back the nanosecond part because
+    // `DateTime::checked_sub_signed()` normalizes leap_seconds, which we want to preserve.
+    fn try_apply_offset<Tz: TimeZone>(
+        local_time: &NaiveDateTime,
+        offset: Tz::Offset,
+    ) -> Option<DateTime<Tz>> {
+        let nanos = local_time.nanosecond();
+        let local_time = local_time.with_nanosecond(0).unwrap();
+        let o = Duration::seconds(offset.fix().local_minus_utc() as i64);
+        let utc_time = local_time.checked_sub_signed(o)?.with_nanosecond(nanos).unwrap();
+        Some(DateTime::from_utc(utc_time, offset))
+    }
+    Some(match local_result {
+        LocalResult::None => LocalResult::None,
+        LocalResult::Single(offset) => LocalResult::Single(try_apply_offset(local_time, offset)?),
+        LocalResult::Ambiguous(o1, o2) => LocalResult::Ambiguous(
+            try_apply_offset(local_time, o1)?,
+            try_apply_offset(local_time, o2)?,
+        ),
+    })
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
 
+    #[test]
+    fn test_fixed_offset_min_max_dates() {
+        for offset_hour in -23..=23 {
+            dbg!(offset_hour);
+            let offset = FixedOffset::east_opt(offset_hour * 60 * 60).unwrap();
+
+            let local_max = offset.from_utc_datetime(&NaiveDateTime::MAX);
+            assert_eq!(local_max.naive_utc(), NaiveDateTime::MAX);
+            let local_min = offset.from_utc_datetime(&NaiveDateTime::MIN);
+            assert_eq!(local_min.naive_utc(), NaiveDateTime::MIN);
+
+            let local_max = offset.from_local_datetime(&NaiveDateTime::MAX);
+            if offset_hour >= 0 {
+                assert_eq!(local_max.unwrap().naive_local(), NaiveDateTime::MAX);
+            } else {
+                assert_eq!(local_max, LocalResult::None);
+            }
+            let local_min = offset.from_local_datetime(&NaiveDateTime::MIN);
+            if offset_hour <= 0 {
+                assert_eq!(local_min.unwrap().naive_local(), NaiveDateTime::MIN);
+            } else {
+                assert_eq!(local_min, LocalResult::None);
+            }
+        }
+    }
+
     #[test]
     fn test_negative_millis() {
         let dt = Utc.timestamp_millis_opt(-1000).unwrap();