API: Floor pre-epoch timestamps when converting to microseconds - #18116
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Align Java temporal conversion with nanosecond precision reduction while retaining checked arithmetic across the full microsecond range. Fixes apache#18115 Generated-by: Codex
Generated-by: Codex
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Hi @laserninja, could you please review the PR first? This would be very helpful for other reviewers and maintainers. |
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@kevinjqliu, yes, I reviewed it. I asked codex to generate the description and missed the |
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Fixes #18115.
Parsing
1969-12-31T23:59:59.999999999directly as a microsecond timestamp returns0, while conversion through a nanosecond timestamp returns-1. Compute microseconds from epoch seconds and the fractional second, and share that conversion across Instant, LocalDateTime, and OffsetDateTime.Checked arithmetic preserves the full long microsecond range, including cases where a negative second's fractional part brings the result back into range.
Compatibility: pre-epoch inputs with a sub-microsecond remainder now floor one microsecond earlier than before, consistent with
nanosToMicros. This can change a derived date at a boundary. Exact-microsecond inputs and stored microsecond values are unchanged. Existing literal-conversion tests that explicitly expected the old behavior are updated.Maintainer decision requested: this changes behavior explicitly asserted by existing tests. Should direct microsecond conversion floor negative fractional inputs to match
nanosToMicros, or should truncation toward zero remain the compatibility contract? The alternative is to preserve the current conversion and document the discrepancy. No maintainer agreement or human review has been recorded yet.Validation on JDK 17: the new regressions failed before the fix; the full API test suite, API formatting/checkstyle, and API
revapichecks passed. Coverage includes public literal conversion, offset handling, positive/exact-unit controls, both long boundaries, and overflow rejection.AI Disclosure