v0.4.20

chrono is a date and time library for Rust and 0.4.20 is the first chrono release since Sep 2020. There has been a long hiatus since the previous maintainer was no longer able to spend much time on the crate; thanks to @quodlibetor for their stewardship of the chrono crate for many years! The new maintainers are @djc and @esheppa. Our first priority has been fixing the soundness issues with calls to localtime_r() as first reported in #499 and the RUSTSEC-2020-0159 advisory. In order to do this we adapted code from the tz-rs crate maintained by @x-hgg-x for use within chrono -- thanks for working on that! With the new implementation, chrono uses safe Rust code to parse the timezone data files on Unix platforms directly instead of relying on libc.

Due to compatibility reasons, this release does not yet remove the time 0.1 dependency, though chrono 0.4.20 does not depend on the vulnerable parts of the time 0.1.x versions. In a future 0.5 release, we will remove the time dependency.

The minimum supported Rust version for 0.4.20 is 1.32.0, which is intentionally still quite conservative. If you are using chrono 0.4 with a Rust version older than 1.52, we'd like to hear from you since we'd like to further modernize the code base to ease maintenance.

Fixes

• Fix unsound call to localtime_r() by parsing timezone files in Rust on Unix (#677 and #728)
• Allow RFC 2822 parser to deal with comments (#733 then #737, thanks to @Finomnis)
• Avoid panicking during parsing (#686, thanks to @botahamec)
• Avoid panics when rounding durations (#659, thanks to @ARBaart)
• Fix Duration::abs() behavior in case of negative durations with nanoseconds (#734, thanks to @abreis)

Additions

• Make ParserErrorKind public and available through ParseError::kind() (#588, thanks to @sbrocket)
• Expose associated MIN and MAX const values in favor of free-standing consts (#726)
• Add (optional) support for rkyv (#644 and #701, thanks to @dovahcrow)
• Support month-based calculations against NaiveDate (#732 with follow up in #752, thanks to @avantgardnerio)
• Add NaiveWeek type to facilitate week-based calculations (#666, thanks to @sestrella)
• Add NaiveDateTime::and_local_timezone() method (#711, thanks to @botahamec)
• Add DateTime::from_local() method (#572, thanks to @retrhelo)
• Extend serde integration for NaiveDateTime (#664, thanks to @nickelc)
• Implement DoubleEndedIterator for NaiveDateDaysIterator/NaiveDateWeeksIterator (#697, thanks to @teobouvard)
• Implement std::iter::Sum for Duration (#522, thanks to @jakevossen5)
• Add years_since() method to DateTime/Date (#557 then #707, thanks to @yozhgoor)
• Implement AddAssign/SubAssign for DateTime/Date (#698, thanks to @MrGunflame)
• Fix imports on WASM targets (#672, thanks to @danielalvsaaker)
• Implement std::error::Error for ParseWeekdayError (#745)

Non-functional improvements

• Improve CI to better exercise WASM targets (#662, thanks to @AmateurECE)
• More WASM testing improvements, enable dependencies by default (#746)
• Fix compiling for wasm32-unknown-emscripten target (#568, thanks to @orion78fr)
• Use stub implementation for anything not unix and not windows (#593, thanks to @yu-re-ka)
• Remove now unused libc dependency (#710, thanks to @metent)
• Clean up some clippy warnings (#721, thanks to @botahamec)
• Clarify documentation for Utc::now() (#647, thanks to @ModProg)
• Clarify documentation for DateTime::with_timezone() (#747, thanks to @kevincox)
• Improve examples for naive serde integration (#616, thanks to @nickelc)
• Clean up extern crate statements and outdated comments (#665, thanks to @nickelc)
• Fix typo in deprecation notice (#744, thanks to @Mike-Dax)
• Fix some typos in documentation (#680 and #695, thanks to @cuishuang and @fxredeemer)
• Implement caching for CI (#609, thanks to @Milo123459)