• fix(tz): reject TZ offset hour of 24 to avoid FixedOffset overflow by @SAY-5 in https://github.com/chronotope/chrono/pull/1787
• tz_data: fix tzdata locations on Android by @caruschalalamove in https://github.com/chronotope/chrono/pull/1789

• docs: match MSRV with Cargo.toml contents by @coryan in https://github.com/chronotope/chrono/pull/1772
• Add track_caller to non-deprecated functions by @svix-jplatte in https://github.com/chronotope/chrono/pull/1774

• Install extra components for lint workflow by @djc in https://github.com/chronotope/chrono/pull/1741
• Upgrade windows-bindgen to 0.64 by @djc in https://github.com/chronotope/chrono/pull/1742
• Improve windows-bindgen setup by @djc in https://github.com/chronotope/chrono/pull/1744
• Drop stabilized feature doc_auto_cfg by @djc in https://github.com/chronotope/chrono/pull/1745
• Faster RFC 3339 parsing by @djc in https://github.com/chronotope/chrono/pull/1748
• Update windows-bindgen requirement from 0.64 to 0.65 by @dependabot[bot] in https://github.com/chronotope/chrono/pull/1751
• add NaiveDate::abs_diff by @Kinrany in https://github.com/chronotope/chrono/pull/1752
• Add feature gated defmt support. by @pebender in https://github.com/chronotope/chrono/pull/1747
• Drop deny lints, eager Debug impls are a mixed blessing by @djc in https://github.com/chronotope/chrono/pull/1753
• chore: minor improvement for docs by @spuradage in https://github.com/chronotope/chrono/pull/1756
• Added doctest for the NaiveDate years_since function by @LucasBou in https://github.com/chronotope/chrono/pull/1755
• Prepare 0.4.43 by @djc in https://github.com/chronotope/chrono/pull/1765
• Update copyright year to 2026 in LICENSE.txt by @taozui472 in https://github.com/chronotope/chrono/pull/1767

• Add fuzzer for DateTime::parse_from_str by @tyler92 in https://github.com/chronotope/chrono/pull/1700
• Fix wrong amount of micro/milliseconds by @nmlt in https://github.com/chronotope/chrono/pull/1703
• Add warning about MappedLocalTime and wasm by @lutzky in https://github.com/chronotope/chrono/pull/1702
• Fix incorrect parsing of fixed-length second fractions by @chris-leach in https://github.com/chronotope/chrono/pull/1705
• Fix cfgs for wasm32-linux support by @arjunr2 in https://github.com/chronotope/chrono/pull/1707
• Fix OpenHarmony's tzdata parsing by @ldm0 in https://github.com/chronotope/chrono/pull/1679
• Convert NaiveDate to/from days since unix epoch by @findepi in https://github.com/chronotope/chrono/pull/1715
• Add ?Sized bound to related methods of DelayedFormat::write_to by @Huliiiiii in https://github.com/chronotope/chrono/pull/1721
• Add from_timestamp_secs method to DateTime by @jasonaowen in https://github.com/chronotope/chrono/pull/1719
• Migrate to core::error::Error by @benbrittain in https://github.com/chronotope/chrono/pull/1704
• Upgrade to windows-bindgen 0.63 by @djc in https://github.com/chronotope/chrono/pull/1730
• strftime: simplify error handling by @djc in https://github.com/chronotope/chrono/pull/1731

• Add subsec_micros and subsec_millis methods to TimeDelta by @ggoetz in https://github.com/chronotope/chrono/pull/1668
• Deprecate NaiveDateTime::UNIX_EPOCH by @robertbastian in https://github.com/chronotope/chrono/pull/1670
• Implement as_seconds_f32 and as_seconds_f64 for TimeDelta by @ggoetz in https://github.com/chronotope/chrono/pull/1671
• chore: fix some comments by @jimmycathy in https://github.com/chronotope/chrono/pull/1677
• Add num_days_in_month method to Datelike trait by @aslilac in https://github.com/chronotope/chrono/pull/1673
• add WeekdaySet, a collection of Weekday that is Copy by @Kinrany in https://github.com/chronotope/chrono/pull/1676
• WeekdaySet tweaks by @djc in https://github.com/chronotope/chrono/pull/1680
• Upgrade to windows-bindgen 0.61 by @djc in https://github.com/chronotope/chrono/pull/1682
• Implemented a consistent Eq trait for NaiveWeek by @Splashling1789 in https://github.com/chronotope/chrono/pull/1687
• TimeZone::from_posix_tz: Treat empty TZ variable as UTC by @drinkcat in https://github.com/chronotope/chrono/pull/1691
• Add support for lossy format strings by @Qelxiros in https://github.com/chronotope/chrono/pull/1693

• Add Month::num_days() by @djc in https://github.com/chronotope/chrono/pull/1645
• Update Windows dependencies by @kennykerr in https://github.com/chronotope/chrono/pull/1646
• Feature/round_up method on DurationRound trait by @MagnumTrader in https://github.com/chronotope/chrono/pull/1651
• Expose write_to for DelayedFormat by @tugtugtug in https://github.com/chronotope/chrono/pull/1654
• Update LICENSE.txt by @maximevtush in https://github.com/chronotope/chrono/pull/1656
• docs: fix minor typo by @samfolo in https://github.com/chronotope/chrono/pull/1659
• Use NaiveDateTime for internal tz_info methods. by @AVee in https://github.com/chronotope/chrono/pull/1658
• Upgrade to windows-bindgen 0.60 by @djc in https://github.com/chronotope/chrono/pull/1665
• Add quarter (%q) date string specifier by @drinkcat in https://github.com/chronotope/chrono/pull/1666

• #1577: Changed years_since documentation to match its implementation by @Taxalo in https://github.com/chronotope/chrono/pull/1578
• Remove obsolete weird feature guard by @djc in https://github.com/chronotope/chrono/pull/1582
• Fix format::strftime docs link by @frederikhors in https://github.com/chronotope/chrono/pull/1581
• Fix micros (optional) limit in and_hms_micro_opt by @qrilka in https://github.com/chronotope/chrono/pull/1584
• Update windows-bindgen requirement from 0.56 to 0.57 by @dependabot in https://github.com/chronotope/chrono/pull/1589
• native/date: Improve DelayedFormat doc re Panics by @behnam-oneschema in https://github.com/chronotope/chrono/pull/1590
• Fix typo in rustdoc of from_timestamp_nanos() by @sgoll in https://github.com/chronotope/chrono/pull/1591
• Update windows-bindgen requirement from 0.57 to 0.58 by @dependabot in https://github.com/chronotope/chrono/pull/1594
• docs: document century cutoff for %y by @MarcoGorelli in https://github.com/chronotope/chrono/pull/1598
• Checked NaiveWeek methods by @bragov4ik in https://github.com/chronotope/chrono/pull/1600
• Impl serde::Serialize and serde::Deserialize for TimeDelta by @Awpteamoose in https://github.com/chronotope/chrono/pull/1599
• Derive PartialEq,Eq,Hash,Copy and Clone on NaiveWeek by @DSeeLP in https://github.com/chronotope/chrono/pull/1618
• Support ohos tzdata since ver.oh35 by @MirageLyu in https://github.com/chronotope/chrono/pull/1613
• Use Formatter::pad (instead of write_str) for Weekdays by @horazont in https://github.com/chronotope/chrono/pull/1621
• Fix typos by @szepeviktor in https://github.com/chronotope/chrono/pull/1623
• Fix comment. by @khuey in https://github.com/chronotope/chrono/pull/1624
• chore: add #[inline] to num_days by @CommanderStorm in https://github.com/chronotope/chrono/pull/1627
• fix typo by @futreall in https://github.com/chronotope/chrono/pull/1633
• Update mod.rs by @donatik27 in https://github.com/chronotope/chrono/pull/1638

This release bring a ca. 20% improvement to the performance of the formatting code, and a convenient days_since method for the Weekday type.

Chrono 0.4.38 also removes the long deprecated rustc-serialize feature. Support for rustc-serialize will be soft-destabilized in the next Rust edition. Removing the feature will not break existing users of the feature; Cargo will just not update dependents that rely on it to newer versions of chrono.

In chrono 0.4.36 we made an accidental breaking change by switching to derive(Copy) for DateTime instead of a manual implementation. It is reverted in this release.

• Remove rustc-serialize feature (#1548, thanks @workingjubilee)

• Add Weekday::days_since (#1249, based on #216 by @clarfonthey)
• Add TimeDelta::checked_mul and TimeDelta::checked_div (#1565, thanks @Zomtir)

• Return error when rounding with a zero duration (#1474, thanks @Dav1dde)
• Manually implement Copy for DateTime if offset is Copy (#1573)

• Inline test_encodable_json and test_decodable_json functions (#1550)
• CI: Reduce combinations in cargo hack check (#1553)
• Refactor formatting code (#1335)
• Optimize number formatting (#1558)
• Only package files needed for building and testing (#1554)

Thanks to all contributors on behalf of the chrono team, @djc and @pitdicker!

• Add '0' to single-digit days in rfc2822 date format (@wyhaya #323)
• Correctly pad DelayedFormat (@SamokhinIlya #320)

• Support wasm-unknown-unknown via wasm-bindgen (in addition to emscripten/wasm-unknown-emscripten). (finished by @evq in #331, initial work by @jjpe #287)

Version 0.4.36 introduced an unexpected breaking change and was yanked. In it LocalResult was renamed to MappedLocalTime to avoid the impression that it is a Result type were some of the results are errors. For backwards compatibility a type alias with the old name was added.

As it turns out there is one case where a type alias behaves differently from the regular enum: you can't import enum variants from a type alias with use chrono::LocalResult::*. With 0.4.37 we make the new name MappedLocalTime the alias, but keep using it in function signatures and the documentation as much as possible.

See also the release notes of chrono 0.4.36 from yesterday for the yanked release.