Sourced from time's releases.

v0.3.42

See the changelog for details.

Sourced from time's changelog.

0.3.42 [2025-08-31]

Added

• Time::duration_until
• Time::duration_since
• per_t method for all types in time::convert. This is similar to the existing per method, but can return any of the primitive numeric types that can represent the result. This will cut down on as casts while ensuring correctness. Type inference isn't perfect, so you may need to provide a type annotation in some situations.
• impl PartialOrd for Month and impl Ord for Month; this assumes the months are in the same year
• SystemTimeExt trait, adding methods for checked arithmetic with time::Duration and obtaining the difference between two SystemTimes as a time::Duration
• Permit using UtcDateTime with rand (this was inadvertently omitted previously)
• impl core::error::Error for all error types (now available when the std feature is disabled)
• MacOS can now obtain the local UTC offset in multi-threaded programs as the system APIs are thread-safe.
• #[track_caller] has been added to all relevant methods.

Changed

• The minimum supported Rust version is now 1.81.0.
• The dependency on itoa has been removed, as the standard library now has similar functionality by default.
• Formatting a component that involves a floating point number is now guaranteed to be deterministic, avoiding any subtle differences between platforms or compiler versions.

Fixed

• Serializing timestamps with nanosecond precision should always emit the correct value. Previously, it could be off by one nanosecond due to floating point imprecision.
• A previously unknown bug in OffsetDateTime::to_offset and UtcDateTime::to_offset has been fixed. The bug could result in a value that was invalid. It was unlikely to ever occur in real-world code, as it involved passing a UTC offset that has never been used in any location.

Miscellaneous

• The amount of code generated by macros has been massively reduced, on the order of 65-70% for typical use cases of format_description!.
• Significant performance gains for comparisons of Time, PrimitiveDateTime, UtcDateTime, and OffsetDateTime. The first three have gains of approximately 85% (i.e. 6× faster).
• Nearly all methods are #[inline].

• ed2852e v0.3.42 release
• 1067543 Fix copied comment
• f45bff5 Use const block for readability
• b38c118 Add #[inline] to most methods
• f410951 Add #[track_caller] to numerous methods
• d30f3d0 Optimize Time::sub
• e807ad3 Add tests, benchmarks
• 3fcb83d Optimize OffsetDateTime comparisons
• 95db5c3 Optimize UTC offset conversions
• 998b26f Optimize Time::duration_until
• Additional commits viewable in compare view

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