Align MIN/MAX/UNIX_EPOCH values across all fmt types using SignedDuration #168

Copilot · 2025-12-29T13:01:30Z

The MIN constants for Iso8601, Rfc2822, and UnixSeconds currently point to UNIX_EPOCH, but jiff supports timestamps back to approximately year -9999.

Changes

Iso8601::MIN and Rfc2822::MIN: Now use Timestamp::MIN (1 January -9999 00:00:00 UTC) instead of UNIX_EPOCH
UnixSeconds::MIN: Changed to use SignedDuration internally and now aligns with other formats (1 January -9999 00:00:00 UTC)
New constants: Added UNIX_EPOCH to all three types for explicit epoch representation (1 January 1970 00:00:00 UTC)
Type change: UnixSeconds now uses SignedDuration internally instead of Duration to support timestamps before the Unix epoch
API encapsulation: SignedDuration is kept internal - only Duration is exposed in the public API via TryFrom<Duration>
Test coverage: Added parse_min tests for all three formats to validate MIN constant behavior

Breaking Changes

UnixSeconds::from_secs() now accepts i64 instead of u64
UnixSeconds::to_secs() now returns i64 instead of u64
UnixSeconds::MIN now represents year -9999 instead of Unix epoch
JSON serialization of UnixSeconds now uses signed integers (i64)
Removed TryFrom<SignedDuration> (jiff type is no longer exposed)
Added TryFrom<Duration> (accepts only positive durations from epoch)

Behavior Notes

All MIN/MAX/UNIX_EPOCH values are now aligned across all three formats:

// All MIN values are now equal (year -9999)
assert_eq!(Iso8601::from(Rfc2822::MIN), Iso8601::MIN);
assert_eq!(UnixSeconds::from(Iso8601::MIN), UnixSeconds::MIN);

// All MAX values remain equal (year 9999)
assert_eq!(Iso8601::from(UnixSeconds::MAX), Iso8601::MAX);

// All UNIX_EPOCH values are equal (1970-01-01)
assert_eq!(Iso8601::from(UnixSeconds::UNIX_EPOCH), Iso8601::UNIX_EPOCH);

Use UNIX_EPOCH when you need a timestamp guaranteed to be formattable/parseable across all formats. Use MIN/MAX to represent the full range supported by jiff.

To create UnixSeconds values, use:

UnixSeconds::from_secs(i64) for positive or negative second values
UnixSeconds::try_from(Duration) for positive durations only
UnixSeconds::try_from(SystemTime) for system time conversions
Conversions from Iso8601 or Rfc2822 types

Original prompt

This section details on the original issue you should resolve

<issue_title>tick: refine the MIN, MAX values for timestamps in fmt module</issue_title>
<issue_description>The tick crate exposes the following formats for SystemTime:

Iso8601

Rfc2822

UnixSeconds

All formats above expose MIN and MAX values. Currently, the MIN points to UNIX_EPOCH while the underlying jiff crate that we are using for parsing and serialization allows even lower min values.

Make the following changes across all 3 formats:

Update the MIN field value to refer to a MIN value as defined by jiff

Introduce UNIX_EPOCH field that that refers to UNICH epoch

</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes tick: refine the MIN, MAX values for timestamps in fmt module #167

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Co-authored-by: martintmk <[email protected]>

codecov · 2025-12-29T13:25:51Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.0%. Comparing base (04bc1b7) to head (2c53275).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #168   +/-   ##
=======================================
  Coverage   100.0%   100.0%           
=======================================
  Files          90       90           
  Lines        6497     6506    +9     
=======================================
+ Hits         6497     6506    +9

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martintmk · 2025-12-29T13:25:01Z

crates/tick/src/fmt/iso_8601.rs


    /// The smallest value that can be represented by `Iso8601`.
    ///
+    /// This represents the minimum timestamp supported by the underlying jiff library,


don't mention jiff, use the same format for the MAX value, just mention the actual MIN value. Apply the same approach to all formats.

Updated MIN documentation to match MAX format (just stating the actual value without mentioning jiff). Applied across all formats in commit e9dc454.

crates/tick/src/fmt/rfc_2822.rs

- Changed UnixSeconds to use SignedDuration instead of Duration - Updated MIN to match Iso8601/Rfc2822 MIN (-9999-01-01) - Simplified MIN documentation to match MAX format - Removed to_unix_epoch_duration() helper methods - All MIN/MAX/UNIX_EPOCH values now aligned across formats - Updated tests to work with signed values Co-authored-by: martintmk <[email protected]>

Co-authored-by: martintmk <[email protected]>

martintmk · 2025-12-29T13:43:51Z

crates/tick/src/fmt/iso_8601.rs

    }

    #[test]
    fn parse_max() {


add parse_min (for all formats)

Added parse_min tests for all three formats (Iso8601, Rfc2822, UnixSeconds) in commit 9212ac6.

martintmk · 2025-12-29T13:46:20Z

crates/tick/src/fmt/unix_seconds.rs

 }

-impl TryFrom<Duration> for UnixSeconds {
+impl TryFrom<SignedDuration> for UnixSeconds {


Hide this method, this exposes jiff SignedDuration which we do not want to expose.

We want to only keep impl TryFrom<Duration> for UnixSeconds which will only ever produce UNixSeconds after UNIX epoch

Hidden TryFrom by replacing it with TryFrom and a private helper method. Only Duration (not SignedDuration) is now exposed in the public API in commit 9212ac6.

- Replaced TryFrom<SignedDuration> with TryFrom<Duration> to avoid exposing jiff types - Added private try_from_signed_duration helper method - Added parse_min tests for all three formats (Iso8601, Rfc2822, UnixSeconds) - Updated tests to use Duration instead of SignedDuration - All 125 tests passing Co-authored-by: martintmk <[email protected]>

Initial plan

836c1b6

Copilot AI assigned Copilot and martintmk Dec 29, 2025

Copilot started work on behalf of martintmk December 29, 2025 13:01 View session

Copilot AI and others added 4 commits December 29, 2025 13:14

Update MIN constants to use jiff's MIN and add UNIX_EPOCH constants

467b812

Co-authored-by: martintmk <[email protected]>

Fix formatting

b5de14e

Co-authored-by: martintmk <[email protected]>

Add documentation about MIN conversion behavior

6b6530d

Co-authored-by: martintmk <[email protected]>

Improve documentation for MIN and UNIX_EPOCH constants

2c53275

Co-authored-by: martintmk <[email protected]>

Copilot AI changed the title ~~[WIP] Refine MIN and MAX values for timestamps in fmt module~~ Expose jiff's MIN timestamp and add UNIX_EPOCH constants to fmt types Dec 29, 2025

Copilot finished work on behalf of martintmk December 29, 2025 13:24

Copilot AI requested a review from martintmk December 29, 2025 13:24

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Copilot started work on behalf of martintmk December 29, 2025 13:28 View session

Copilot AI and others added 2 commits December 29, 2025 13:36

Fix Duration import in rfc_2822 tests

3fbdf7b

Co-authored-by: martintmk <[email protected]>

Copilot AI changed the title ~~Expose jiff's MIN timestamp and add UNIX_EPOCH constants to fmt types~~ Align MIN/MAX/UNIX_EPOCH values across all fmt types using SignedDuration Dec 29, 2025

Copilot AI requested a review from martintmk December 29, 2025 13:40

Copilot finished work on behalf of martintmk December 29, 2025 13:40

martintmk requested changes Dec 29, 2025

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Copilot started work on behalf of martintmk December 29, 2025 13:48 View session

Copilot AI requested a review from martintmk December 29, 2025 13:55

Copilot finished work on behalf of martintmk December 29, 2025 13:55

geeknoid approved these changes Dec 29, 2025

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Align MIN/MAX/UNIX_EPOCH values across all fmt types using SignedDuration #168

Align MIN/MAX/UNIX_EPOCH values across all fmt types using SignedDuration #168

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Align MIN/MAX/UNIX_EPOCH values across all fmt types using SignedDuration #168

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