[ac1982]

What type of PR is this?

• bug

What this PR does / why we need it:

TimestampFlag replaces a parsed year of zero with the current year even when the layout and input explicitly contain 0000. For example, --time 0000-02-29T12:34:56Z with time.RFC3339 becomes March 1 of the current non-leap year instead of preserving the supplied timestamp.

Distinguish an omitted year from an explicit zero year by probing the matched layout, just as the existing date-presence helper does. Preserve yearless/time-only defaulting. Add CLI-level regressions for RFC3339, a full date, and a year-plus-time layout.

Which issue(s) this PR fixes:

No existing issue found. Searched timestamp/year issues and open/closed PRs, including #2427 and #2450; those address layouts without a year rather than an explicitly supplied year zero.

Testing

• All three new cases fail before the fix.
• go test ./... passed, including the existing yearless and time-only timezone cases.
• go vet ./... passed.
• make v3diff passed (no public API change).
• Files formatted with gofmt. Full make all / gfmrun documentation checks were not run.

Release Notes

TimestampFlag preserves an explicitly supplied year 0000 instead of replacing it with the current year.

[greptile-apps]

Confidence Score: 5/5

[Medium risk] Fixes timestamp parsing to preserve explicit year zero.

The PR appears safe to merge.

Summary

The PR preserves an explicitly parsed year zero in TimestampFlag while retaining defaulting for layouts that omit the year. It adds CLI-level regression tests for three year-bearing layouts.

_{Reviews (1) · Last reviewed commit: "fix: preserve explicit year zero in time..." · Reviewed by Greptile}

[Juneezee]

Thanks, the fix looks correct. The three new cases fail on main and pass here, and yearless layouts such as "01-02" and "15:04" still default to the current year/date.

I pushed 029b760, which merges layoutHasDate and layoutHasYear into one probe, since both round-tripped the same reference time with different reference years (2 and 2001):

cli/flag_timestamp.go

Lines 130 to 139 in 029b760

	// layoutFields reports whether layout carries a year and month/day components,
	// probed by round-tripping a reference date that is not January 1 of year 0.
	func layoutFields(layout string) (hasYear, hasDate bool) {
	ref := time.Date(2, time.March, 4, 5, 6, 7, 0, time.UTC)
	if p, err := time.Parse(layout, ref.Format(layout)); err == nil {
	hasYear = p.Year() != 0
	hasDate = p.Month() != time.January || p.Day() != 1
	}
	return hasYear, hasDate
	}

An omitted year always parses as year 0, and "06" never parses as 0 (00 is 2000), so p.Year() != 0 is enough to tell whether the layout carries a year.