FA-76958 / Calendar recurrence rules / Member archive

Yearly BYMONTH/BYMONTHDAY with leap-day skipping: dtstart date compare · case 03

A series starting after the anniversary returns no instances at all.

Member previewVariant 3 · 3 implementations · 7 checks per implementation

Case contract

FREQ=YEARLY on a fixed month and day. Years are dtstart.year + k*interval. A year in which the date does not exist (for example February 29 in a common year) is skipped, never clamped. Gregorian leap years: divisible by 4, except centuries not divisible by 400. Instances before dtstart are dropped and the series ends at until (inclusive). Return ISO dates.

Why this case matters

Recurring calendar series are expanded into concrete instances for display, reminders and conflict checks.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
same month earlier day	`[]`	`["2025-05-10", "2026-05-10", "2027-05-10"]`	Failed

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