LibJS: Use relative date in NudgeToCalendarUnit when comparing durations

This is a normative change in the Temporal proposal. See:
17e12be

The test added here would previously crash.

Libraries/LibJS/Runtime/Temporal/Duration.cpp

@@ -847,8 +847,8 @@ Crypto::BigFraction total_time_duration(TimeDuration const& time_duration, Unit
     return Crypto::BigFraction { time_duration } / Crypto::BigFraction { Crypto::SignedBigInteger { divisor } };
 }
 
-// 7.5.33 NudgeToCalendarUnit ( sign, duration, originEpochNs, destEpochNs, isoDateTime, timeZone, calendar, increment, unit, roundingMode ), https://tc39.es/proposal-temporal/#sec-temporal-nudgetocalendarunit
+// 7.5.33 ComputeNudgeWindow ( sign, duration, originEpochNs, isoDateTime, timeZone, calendar, increment, unit, additionalShift ), https://tc39.es/proposal-temporal/#sec-temporal-computenudgewindow
-ThrowCompletionOr<CalendarNudgeResult> nudge_to_calendar_unit(VM& vm, i8 sign, InternalDuration const& duration, Crypto::SignedBigInteger const& origin_epoch_ns, Crypto::SignedBigInteger const& dest_epoch_ns, ISODateTime const& iso_date_time, Optional<StringView> time_zone, StringView calendar, u64 increment, Unit unit, RoundingMode rounding_mode)
+ThrowCompletionOr<NudgeWindow> compute_nudge_window(VM& vm, i8 sign, InternalDuration const& duration, Crypto::SignedBigInteger const& origin_epoch_ns, ISODateTime const& iso_date_time, Optional<StringView> time_zone, StringView calendar, u64 increment, Unit unit, bool additional_shift)
 {
     DateDuration start_duration;
     DateDuration end_duration;
@@ -856,21 +856,26 @@ ThrowCompletionOr<CalendarNudgeResult> nudge_to_calendar_unit(VM& vm, i8 sign, I
     double r1 = 0;
     double r2 = 0;
 
+    auto signed_increment = static_cast<double>(increment) * sign;
+
     // 1. If unit is YEAR, then
     if (unit == Unit::Year) {
         // a. Let years be RoundNumberToIncrement(duration.[[Date]].[[Years]], increment, TRUNC).
         auto years = round_number_to_increment(duration.date.years, increment, RoundingMode::Trunc);
 
-        // b. Let r1 be years.
+        // b. If additionalShift is false, then
-        r1 = years;
+        //     i. Let r1 be years.
+        // c. Else,
+        //     i. Let r1 be years + increment × sign.
+        r1 = additional_shift ? years + signed_increment : years;
 
-        // c. Let r2 be years + increment × sign.
+        // d. Let r2 be r1 + increment × sign.
-        r2 = years + static_cast<double>(increment) * sign;
+        r2 = r1 + signed_increment;
 
-        // d. Let startDuration be ? CreateDateDurationRecord(r1, 0, 0, 0).
+        // e. Let startDuration be ? CreateDateDurationRecord(r1, 0, 0, 0).
         start_duration = TRY(create_date_duration_record(vm, r1, 0, 0, 0));
 
-        // e. Let endDuration be ? CreateDateDurationRecord(r2, 0, 0, 0).
+        // f. Let endDuration be ? CreateDateDurationRecord(r2, 0, 0, 0).
         end_duration = TRY(create_date_duration_record(vm, r2, 0, 0, 0));
     }
     // 2. Else if unit is MONTH, then
@@ -878,16 +883,19 @@ ThrowCompletionOr<CalendarNudgeResult> nudge_to_calendar_unit(VM& vm, i8 sign, I
         // a. Let months be RoundNumberToIncrement(duration.[[Date]].[[Months]], increment, TRUNC).
         auto months = round_number_to_increment(duration.date.months, increment, RoundingMode::Trunc);
 
-        // b. Let r1 be months.
+        // b. If additionalShift is false, then
-        r1 = months;
+        //     i. Let r1 be months.
+        // c. Else,
+        //     i. Let r1 be months + increment × sign.
+        r1 = additional_shift ? months + signed_increment : months;
 
-        // c. Let r2 be months + increment × sign.
+        // d. Let r2 be r1 + increment × sign.
-        r2 = months + static_cast<double>(increment) * sign;
+        r2 = r1 + signed_increment;
 
-        // d. Let startDuration be ? AdjustDateDurationRecord(duration.[[Date]], 0, 0, r1).
+        // e. Let startDuration be ? AdjustDateDurationRecord(duration.[[Date]], 0, 0, r1).
         start_duration = TRY(adjust_date_duration_record(vm, duration.date, 0, 0, r1));
 
-        // e. Let endDuration be ? AdjustDateDurationRecord(duration.[[Date]], 0, 0, r2).
+        // f. Let endDuration be ? AdjustDateDurationRecord(duration.[[Date]], 0, 0, r2).
         end_duration = TRY(adjust_date_duration_record(vm, duration.date, 0, 0, r2));
     }
     // 3. Else if unit is WEEK, then
@@ -911,7 +919,7 @@ ThrowCompletionOr<CalendarNudgeResult> nudge_to_calendar_unit(VM& vm, i8 sign, I
         r1 = weeks;
 
         // g. Let r2 be weeks + increment × sign.
-        r2 = weeks + static_cast<double>(increment) * sign;
+        r2 = weeks + signed_increment;
 
         // h. Let startDuration be ? AdjustDateDurationRecord(duration.[[Date]], 0, r1).
         start_duration = TRY(adjust_date_duration_record(vm, duration.date, 0, r1));
@@ -931,7 +939,7 @@ ThrowCompletionOr<CalendarNudgeResult> nudge_to_calendar_unit(VM& vm, i8 sign, I
         r1 = days;
 
         // d. Let r2 be days + increment × sign.
-        r2 = days + static_cast<double>(increment) * sign;
+        r2 = days + signed_increment;
 
         // e. Let startDuration be ? AdjustDateDurationRecord(duration.[[Date]], r1).
         start_duration = TRY(adjust_date_duration_record(vm, duration.date, r1));
@@ -992,28 +1000,87 @@ ThrowCompletionOr<CalendarNudgeResult> nudge_to_calendar_unit(VM& vm, i8 sign, I
         end_epoch_ns = TRY(get_epoch_nanoseconds_for(vm, *time_zone, end_date_time, Disambiguation::Compatible));
     }
 
-    // 13. If sign is 1, then
+    // 13. Return the Record { [[R1]]: r1, [[R2]]: r2, [[StartEpochNs]]: startEpochNs, [[EndEpochNs]]: endEpochNs, [[StartDuration]]: startDuration, [[EndDuration]]: endDuration }.
+    return NudgeWindow { r1, r2, move(start_epoch_ns), move(end_epoch_ns), start_duration, end_duration };
+}
+
+// 7.5.34 NudgeToCalendarUnit ( sign, duration, originEpochNs, destEpochNs, isoDateTime, timeZone, calendar, increment, unit, roundingMode ), https://tc39.es/proposal-temporal/#sec-temporal-nudgetocalendarunit
+ThrowCompletionOr<CalendarNudgeResult> nudge_to_calendar_unit(VM& vm, i8 sign, InternalDuration const& duration, Crypto::SignedBigInteger const& origin_epoch_ns, Crypto::SignedBigInteger const& dest_epoch_ns, ISODateTime const& iso_date_time, Optional<StringView> time_zone, StringView calendar, u64 increment, Unit unit, RoundingMode rounding_mode)
+{
+    // 1. Let didExpandCalendarUnit be false.
+    auto did_expand_calendar_unit = false;
+
+    // 2. Let nudgeWindow be ? ComputeNudgeWindow(sign, duration, originEpochNs, isoDateTime, timeZone, calendar, increment, unit, false).
+    auto nudge_window = TRY(compute_nudge_window(vm, sign, duration, origin_epoch_ns, iso_date_time, time_zone, calendar, increment, unit, false));
+
+    // 3. Let startEpochNs be nudgeWindow.[[StartEpochNs]].
+    auto start_epoch_ns = move(nudge_window.start_epoch_ns);
+
+    // 4. Let endEpochNs be nudgeWindow.[[EndEpochNs]].
+    auto end_epoch_ns = move(nudge_window.end_epoch_ns);
+
+    auto recompute_nudge_window = [&]() -> ThrowCompletionOr<void> {
+        nudge_window = TRY(compute_nudge_window(vm, sign, duration, origin_epoch_ns, iso_date_time, time_zone, calendar, increment, unit, true));
+        start_epoch_ns = move(nudge_window.start_epoch_ns);
+        end_epoch_ns = move(nudge_window.end_epoch_ns);
+        return {};
+    };
+
+    // 5. If sign is 1, then
     if (sign == 1) {
-        // a. Assert: startEpochNs ≤ destEpochNs ≤ endEpochNs.
+        // a. If startEpochNs ≤ destEpochNs ≤ endEpochNs is false, then
-        VERIFY(start_epoch_ns <= dest_epoch_ns);
+        if (start_epoch_ns > dest_epoch_ns || dest_epoch_ns > end_epoch_ns) {
-        VERIFY(dest_epoch_ns <= end_epoch_ns);
+            // i. Set nudgeWindow to ? ComputeNudgeWindow(sign, duration, originEpochNs, isoDateTime, timeZone, calendar, increment, unit, true).
+            TRY(recompute_nudge_window());
+
+            // ii. Assert: nudgeWindow.[[StartEpochNs]] ≤ destEpochNs ≤ nudgeWindow.[[EndEpochNs]].
+            VERIFY(start_epoch_ns <= dest_epoch_ns);
+            VERIFY(dest_epoch_ns <= end_epoch_ns);
+
+            // iii. Set didExpandCalendarUnit to true.
+            did_expand_calendar_unit = true;
+        }
     }
-    // 14. Else,
+    // 6. Else,
     else {
-        // a. Assert: endEpochNs ≤ destEpochNs ≤ startEpochNs.
+        // a. If endEpochNs ≤ destEpochNs ≤ startEpochNs is false, then
-        VERIFY(end_epoch_ns <= dest_epoch_ns);
+        if (end_epoch_ns > dest_epoch_ns || dest_epoch_ns > start_epoch_ns) {
-        VERIFY(dest_epoch_ns <= start_epoch_ns);
+            // i. Set nudgeWindow to ? ComputeNudgeWindow(sign, duration, originEpochNs, isoDateTime, timeZone, calendar, increment, unit, true).
+            TRY(recompute_nudge_window());
+
+            // ii. Assert: nudgeWindow.[[EndEpochNs]] ≤ destEpochNs ≤ nudgeWindow.[[StartEpochNs]].
+            VERIFY(end_epoch_ns <= dest_epoch_ns);
+            VERIFY(dest_epoch_ns <= start_epoch_ns);
+
+            // iii. Set didExpandCalendarUnit to true.
+            did_expand_calendar_unit = true;
+        }
     }
 
-    // 15. Assert: startEpochNs ≠ endEpochNs.
+    // 7. Let r1 be nudgeWindow.[[R1]].
+    auto r1 = nudge_window.r1;
+
+    // 8. Let r2 be nudgeWindow.[[R2]].
+    auto r2 = nudge_window.r2;
+
+    // 9. Set startEpochNs to nudgeWindow.[[StartEpochNs]].
+    // 10. Set endEpochNs to nudgeWindow.[[StartEpochNs]].
+
+    // 11. Let startDuration be nudgeWindow.[[StartDuration]].
+    auto start_duration = nudge_window.start_duration;
+
+    // 12. Let endDuration be nudgeWindow.[[EndDuration]].
+    auto end_duration = nudge_window.end_duration;
+
+    // 13. Assert: startEpochNs ≠ endEpochNs.
     VERIFY(start_epoch_ns != end_epoch_ns);
 
-    // 16. Let progress be (destEpochNs - startEpochNs) / (endEpochNs - startEpochNs).
+    // 14. Let progress be (destEpochNs - startEpochNs) / (endEpochNs - startEpochNs).
     auto progress_numerator = dest_epoch_ns.minus(start_epoch_ns);
     auto progress_denominator = end_epoch_ns.minus(start_epoch_ns);
     auto progress_equals_one = progress_numerator == progress_denominator;
 
-    // 17. Let total be r1 + progress × increment × sign.
+    // 15. Let total be r1 + progress × increment × sign.
     auto total_numerator = progress_numerator.multiplied_by(Crypto::UnsignedBigInteger { increment });
 
     if (sign == -1)
@@ -1024,26 +1091,26 @@ ThrowCompletionOr<CalendarNudgeResult> nudge_to_calendar_unit(VM& vm, i8 sign, I
     auto total_mv = Crypto::BigFraction { Crypto::SignedBigInteger { r1 } } + Crypto::BigFraction { move(total_numerator), progress_denominator.unsigned_value() };
     auto total = total_mv.to_double();
 
-    // 18. NOTE: The above two steps cannot be implemented directly using floating-point arithmetic. This division can be
+    // 16. NOTE: The above two steps cannot be implemented directly using floating-point arithmetic. This division can be
     //     implemented as if expressing the denominator and numerator of total as two time durations, and performing one
     //     division operation with a floating-point result.
 
-    // 19. Assert: 0 ≤ progress ≤ 1.
+    // 17. Assert: 0 ≤ progress ≤ 1.
 
-    // 20. If sign < 0, let isNegative be NEGATIVE; else let isNegative be POSITIVE.
+    // 18. If sign < 0, let isNegative be NEGATIVE; else let isNegative be POSITIVE.
     auto is_negative = sign < 0 ? Sign::Negative : Sign::Positive;
 
-    // 21. Let unsignedRoundingMode be GetUnsignedRoundingMode(roundingMode, isNegative).
+    // 19. Let unsignedRoundingMode be GetUnsignedRoundingMode(roundingMode, isNegative).
     auto unsigned_rounding_mode = get_unsigned_rounding_mode(rounding_mode, is_negative);
 
     double rounded_unit = 0;
 
-    // 22. If progress = 1, then
+    // 20. If progress = 1, then
     if (progress_equals_one) {
         // a. Let roundedUnit be abs(r2).
         rounded_unit = fabs(r2);
     }
-    // 23. Else,
+    // 21. Else,
     else {
         // a. Assert: abs(r1) ≤ abs(total) < abs(r2).
         VERIFY(fabs(r1) <= fabs(total));
@@ -1053,13 +1120,12 @@ ThrowCompletionOr<CalendarNudgeResult> nudge_to_calendar_unit(VM& vm, i8 sign, I
         rounded_unit = apply_unsigned_rounding_mode(fabs(total), fabs(r1), fabs(r2), unsigned_rounding_mode);
     }
 
-    auto did_expand_calendar_unit = false;
     DateDuration result_duration;
     Crypto::SignedBigInteger nudged_epoch_ns;
 
-    // 24. If roundedUnit is abs(r2), then
+    // 22. If roundedUnit is abs(r2), then
     if (rounded_unit == fabs(r2)) {
-        // a. Let didExpandCalendarUnit be true.
+        // a. Set didExpandCalendarUnit to true.
         did_expand_calendar_unit = true;
 
         // b. Let resultDuration be endDuration.
@@ -1068,29 +1134,26 @@ ThrowCompletionOr<CalendarNudgeResult> nudge_to_calendar_unit(VM& vm, i8 sign, I
         // c. Let nudgedEpochNs be endEpochNs.
         nudged_epoch_ns = move(end_epoch_ns);
     }
-    // 25. Else,
+    // 23. Else,
     else {
-        // a. Let didExpandCalendarUnit be false.
+        // a. Let resultDuration be startDuration.
-        did_expand_calendar_unit = false;
-
-        // b. Let resultDuration be startDuration.
         result_duration = start_duration;
 
-        // c. Let nudgedEpochNs be startEpochNs.
+        // b. Let nudgedEpochNs be startEpochNs.
         nudged_epoch_ns = move(start_epoch_ns);
     }
 
-    // 26. Set resultDuration to CombineDateAndTimeDuration(resultDuration, 0).
+    // 24. Set resultDuration to CombineDateAndTimeDuration(resultDuration, 0).
     auto result_date_and_time_duration = combine_date_and_time_duration(result_duration, TimeDuration { 0 });
 
-    // 27. Let nudgeResult be Duration Nudge Result Record { [[Duration]]: resultDuration, [[NudgedEpochNs]]: nudgedEpochNs, [[DidExpandCalendarUnit]]: didExpandCalendarUnit }.
+    // 25. Let nudgeResult be Duration Nudge Result Record { [[Duration]]: resultDuration, [[NudgedEpochNs]]: nudgedEpochNs, [[DidExpandCalendarUnit]]: didExpandCalendarUnit }.
     DurationNudgeResult nudge_result { .duration = move(result_date_and_time_duration), .nudged_epoch_ns = move(nudged_epoch_ns), .did_expand_calendar_unit = did_expand_calendar_unit };
 
-    // 28. Return the Record { [[NudgeResult]]: nudgeResult, [[Total]]: total }.
+    // 26. Return the Record { [[NudgeResult]]: nudgeResult, [[Total]]: total }.
     return CalendarNudgeResult { .nudge_result = move(nudge_result), .total = move(total_mv) };
 }
 
-// 7.5.34 NudgeToZonedTime ( sign, duration, isoDateTime, timeZone, calendar, increment, unit, roundingMode ), https://tc39.es/proposal-temporal/#sec-temporal-nudgetozonedtime
+// 7.5.35 NudgeToZonedTime ( sign, duration, isoDateTime, timeZone, calendar, increment, unit, roundingMode ), https://tc39.es/proposal-temporal/#sec-temporal-nudgetozonedtime
 ThrowCompletionOr<DurationNudgeResult> nudge_to_zoned_time(VM& vm, i8 sign, InternalDuration const& duration, ISODateTime const& iso_date_time, StringView time_zone, StringView calendar, u64 increment, Unit unit, RoundingMode rounding_mode)
 {
     // 1. Let start be ? CalendarDateAdd(calendar, isoDateTime.[[ISODate]], duration.[[Date]], CONSTRAIN).
@@ -1168,7 +1231,7 @@ ThrowCompletionOr<DurationNudgeResult> nudge_to_zoned_time(VM& vm, i8 sign, Inte
     return DurationNudgeResult { .duration = move(result_duration), .nudged_epoch_ns = move(nudged_epoch_ns), .did_expand_calendar_unit = did_round_beyond_day };
 }
 
-// 7.5.35 NudgeToDayOrTime ( duration, destEpochNs, largestUnit, increment, smallestUnit, roundingMode ), https://tc39.es/proposal-temporal/#sec-temporal-nudgetodayortime
+// 7.5.36 NudgeToDayOrTime ( duration, destEpochNs, largestUnit, increment, smallestUnit, roundingMode ), https://tc39.es/proposal-temporal/#sec-temporal-nudgetodayortime
 ThrowCompletionOr<DurationNudgeResult> nudge_to_day_or_time(VM& vm, InternalDuration const& duration, Crypto::SignedBigInteger const& dest_epoch_ns, Unit largest_unit, u64 increment, Unit smallest_unit, RoundingMode rounding_mode)
 {
     // 1. Let timeDuration be ! Add24HourDaysToTimeDuration(duration.[[Time]], duration.[[Date]].[[Days]]).
@@ -1231,7 +1294,7 @@ ThrowCompletionOr<DurationNudgeResult> nudge_to_day_or_time(VM& vm, InternalDura
     return DurationNudgeResult { .duration = move(result_duration), .nudged_epoch_ns = move(nudged_epoch_ns), .did_expand_calendar_unit = did_expand_days };
 }
 
-// 7.5.36 BubbleRelativeDuration ( sign, duration, nudgedEpochNs, isoDateTime, timeZone, calendar, largestUnit, smallestUnit ), https://tc39.es/proposal-temporal/#sec-temporal-bubblerelativeduration
+// 7.5.37 BubbleRelativeDuration ( sign, duration, nudgedEpochNs, isoDateTime, timeZone, calendar, largestUnit, smallestUnit ), https://tc39.es/proposal-temporal/#sec-temporal-bubblerelativeduration
 ThrowCompletionOr<InternalDuration> bubble_relative_duration(VM& vm, i8 sign, InternalDuration duration, Crypto::SignedBigInteger const& nudged_epoch_ns, ISODateTime const& iso_date_time, Optional<StringView> time_zone, StringView calendar, Unit largest_unit, Unit smallest_unit)
 {
     // 1. If smallestUnit is largestUnit, return duration.
@@ -1332,7 +1395,7 @@ ThrowCompletionOr<InternalDuration> bubble_relative_duration(VM& vm, i8 sign, In
     return duration;
 }
 
-// 7.5.37 RoundRelativeDuration ( duration, originEpochNs, destEpochNs, isoDateTime, timeZone, calendar, largestUnit, increment, smallestUnit, roundingMode ), https://tc39.es/proposal-temporal/#sec-temporal-roundrelativeduration
+// 7.5.38 RoundRelativeDuration ( duration, originEpochNs, destEpochNs, isoDateTime, timeZone, calendar, largestUnit, increment, smallestUnit, roundingMode ), https://tc39.es/proposal-temporal/#sec-temporal-roundrelativeduration
 ThrowCompletionOr<InternalDuration> round_relative_duration(VM& vm, InternalDuration duration, Crypto::SignedBigInteger const& origin_epoch_ns, Crypto::SignedBigInteger const& dest_epoch_ns, ISODateTime const& iso_date_time, Optional<StringView> time_zone, StringView calendar, Unit largest_unit, u64 increment, Unit smallest_unit, RoundingMode rounding_mode)
 {
     // 1. Let irregularLengthUnit be false.
@@ -1386,7 +1449,7 @@ ThrowCompletionOr<InternalDuration> round_relative_duration(VM& vm, InternalDura
     return duration;
 }
 
-// 7.5.38 TotalRelativeDuration ( duration, originEpochNs, destEpochNs, isoDateTime, timeZone, calendar, unit ), https://tc39.es/proposal-temporal/#sec-temporal-totalrelativeduration
+// 7.5.39 TotalRelativeDuration ( duration, originEpochNs, destEpochNs, isoDateTime, timeZone, calendar, unit ), https://tc39.es/proposal-temporal/#sec-temporal-totalrelativeduration
 ThrowCompletionOr<Crypto::BigFraction> total_relative_duration(VM& vm, InternalDuration const& duration, Crypto::SignedBigInteger const& origin_epoch_ns, Crypto::SignedBigInteger const& dest_epoch_ns, ISODateTime const& iso_date_time, Optional<StringView> time_zone, StringView calendar, Unit unit)
 {
     // 1. If IsCalendarUnit(unit) is true, or timeZone is not UNSET and unit is DAY, then
@@ -1408,7 +1471,7 @@ ThrowCompletionOr<Crypto::BigFraction> total_relative_duration(VM& vm, InternalD
     return total_time_duration(time_duration, unit);
 }
 
-// 7.5.39 TemporalDurationToString ( duration, precision ), https://tc39.es/proposal-temporal/#sec-temporal-temporaldurationtostring
+// 7.5.40 TemporalDurationToString ( duration, precision ), https://tc39.es/proposal-temporal/#sec-temporal-temporaldurationtostring
 String temporal_duration_to_string(Duration const& duration, Precision precision)
 {
     // 1. Let sign be DurationSign(duration).
@@ -1500,7 +1563,7 @@ String temporal_duration_to_string(Duration const& duration, Precision precision
     return MUST(result.to_string());
 }
 
-// 7.5.40 AddDurations ( operation, duration, other ), https://tc39.es/proposal-temporal/#sec-temporal-adddurations
+// 7.5.41 AddDurations ( operation, duration, other ), https://tc39.es/proposal-temporal/#sec-temporal-adddurations
 ThrowCompletionOr<GC::Ref<Duration>> add_durations(VM& vm, ArithmeticOperation operation, Duration const& duration, Value other_value)
 {
     // 1. Set other to ? ToTemporalDuration(other).

Libraries/LibJS/Runtime/Temporal/Duration.h

@@ -104,6 +104,15 @@ struct DurationNudgeResult {
     bool did_expand_calendar_unit { false };
 };
 
+struct NudgeWindow {
+    double r1 { 0 };
+    double r2 { 0 };
+    Crypto::SignedBigInteger start_epoch_ns;
+    Crypto::SignedBigInteger end_epoch_ns;
+    DateDuration start_duration;
+    DateDuration end_duration;
+};
+
 struct CalendarNudgeResult {
     DurationNudgeResult nudge_result;
     Crypto::BigFraction total;
@@ -137,6 +146,7 @@ i8 time_duration_sign(TimeDuration const&);
 ThrowCompletionOr<double> date_duration_days(VM&, DateDuration const&, PlainDate const&);
 ThrowCompletionOr<TimeDuration> round_time_duration(VM&, TimeDuration const&, Crypto::UnsignedBigInteger const& increment, Unit, RoundingMode);
 Crypto::BigFraction total_time_duration(TimeDuration const&, Unit);
+ThrowCompletionOr<NudgeWindow> compute_nudge_window(VM&, i8 sign, InternalDuration const&, Crypto::SignedBigInteger const& origin_epoch_ns, ISODateTime const& iso_date_time, Optional<StringView> time_zone, StringView calendar, u64 increment, Unit, bool additional_shift);
 ThrowCompletionOr<CalendarNudgeResult> nudge_to_calendar_unit(VM&, i8 sign, InternalDuration const&, Crypto::SignedBigInteger const& origin_epoch_ns, Crypto::SignedBigInteger const& dest_epoch_ns, ISODateTime const&, Optional<StringView> time_zone, StringView calendar, u64 increment, Unit, RoundingMode);
 ThrowCompletionOr<DurationNudgeResult> nudge_to_zoned_time(VM&, i8 sign, InternalDuration const&, ISODateTime const&, StringView time_zone, StringView calendar, u64 increment, Unit, RoundingMode);
 ThrowCompletionOr<DurationNudgeResult> nudge_to_day_or_time(VM&, InternalDuration const&, Crypto::SignedBigInteger const& dest_epoch_ns, Unit largest_unit, u64 increment, Unit smallest_unit, RoundingMode);

Libraries/LibJS/Tests/builtins/Temporal/Duration/Duration.prototype.round.js

@@ -120,6 +120,14 @@ describe("correct behavior", () => {
 
         expect(result.toString()).toBe("PT0S");
     });
+
+    test("leap day rounding", () => {
+        const duration = new Temporal.Duration(1, 0, 0, 0, 1);
+        const relativeTo = new Temporal.PlainDate(2020, 2, 29);
+
+        const result = duration.round({ smallestUnit: "years", relativeTo });
+        expect(result.toString()).toBe("P1Y");
+    });
 });
 
 describe("errors", () => {