Normative: Throw on conversion from TimeZone to Calendar and vice versa

In order to prevent bugs like `new Temporal.ZonedDateTime(0n, cal, tz)`
(where the calendar and time zone arguments are switched, silently
poisoning the object) ToTemporalCalendar should throw if it encounters a
Temporal.TimeZone instance, and ToTemporalTimeZone should throw if it
encounters a Temporal.Calendar instance.

Includes implementation in the reference code.

Co-authored-by: Aditi <aditisingh1400@gmail.com>

Closes: #2354

Author: ptomato

polyfill/lib/ecmascript.mjs

@@ -1683,9 +1683,17 @@ export const ES = ObjectAssign({}, ES2022, {
     if (ES.Type(calendarLike) === 'Object') {
       if (ES.IsTemporalCalendar(calendarLike)) return calendarLike;
       if (HasSlot(calendarLike, CALENDAR)) return GetSlot(calendarLike, CALENDAR);
+      if (ES.IsTemporalTimeZone(calendarLike)) {
+        throw new RangeError('Expected a calendar object but received a Temporal.TimeZone');
+      }
       if (!('calendar' in calendarLike)) return calendarLike;
       calendarLike = calendarLike.calendar;
-      if (ES.Type(calendarLike) === 'Object' && !('calendar' in calendarLike)) return calendarLike;
+      if (ES.Type(calendarLike) === 'Object') {
+        if (ES.IsTemporalTimeZone(calendarLike)) {
+          throw new RangeError('Expected a calendar object as the calendar property but received a Temporal.TimeZone');
+        }
+        if (!('calendar' in calendarLike)) return calendarLike;
+      }
     }
     const identifier = ES.ToString(calendarLike);
     const TemporalCalendar = GetIntrinsic('%Temporal.Calendar%');
@@ -1746,10 +1754,16 @@ export const ES = ObjectAssign({}, ES2022, {
     if (ES.Type(temporalTimeZoneLike) === 'Object') {
       if (ES.IsTemporalTimeZone(temporalTimeZoneLike)) return temporalTimeZoneLike;
       if (ES.IsTemporalZonedDateTime(temporalTimeZoneLike)) return GetSlot(temporalTimeZoneLike, TIME_ZONE);
+      if (ES.IsTemporalCalendar(temporalTimeZoneLike)) {
+        throw new RangeError('Expected a time zone object but received a Temporal.Calendar');
+      }
       if (!('timeZone' in temporalTimeZoneLike)) return temporalTimeZoneLike;
       temporalTimeZoneLike = temporalTimeZoneLike.timeZone;
-      if (ES.Type(temporalTimeZoneLike) === 'Object' && !('timeZone' in temporalTimeZoneLike)) {
-        return temporalTimeZoneLike;
+      if (ES.Type(temporalTimeZoneLike) === 'Object') {
+        if (ES.IsTemporalCalendar(temporalTimeZoneLike)) {
+          throw new RangeError('Expected a time zone object as the timeZone property but received a Temporal.Calendar');
+        }
+        if (!('timeZone' in temporalTimeZoneLike)) return temporalTimeZoneLike;
       }
     }
     const identifier = ES.ToString(temporalTimeZoneLike);

spec/calendar.html

@@ -367,9 +367,12 @@ <h1>ToTemporalCalendar ( _temporalCalendarLike_ )</h1>
             1. Return _temporalCalendarLike_.
           1. If _temporalCalendarLike_ has an [[InitializedTemporalDate]], [[InitializedTemporalDateTime]], [[InitializedTemporalMonthDay]], [[InitializedTemporalTime]], [[InitializedTemporalYearMonth]], or [[InitializedTemporalZonedDateTime]] internal slot, then
             1. Return _temporalCalendarLike_.[[Calendar]].
+          1. If _temporalCalendarLike_ has an [[InitializedTemporalTimeZone]] internal slot, throw a *RangeError* exception.
           1. If ? HasProperty(_temporalCalendarLike_, *"calendar"*) is *false*, return _temporalCalendarLike_.
           1. Set _temporalCalendarLike_ to ? Get(_temporalCalendarLike_, *"calendar"*).
-          1. If Type(_temporalCalendarLike_) is Object and ? HasProperty(_temporalCalendarLike_, *"calendar"*) is *false*, return _temporalCalendarLike_.
+          1. If Type(_temporalCalendarLike_) is Object, then
+            1. If _temporalCalendarLike_ has an [[InitializedTemporalTimeZone]] internal slot, throw a *RangeError* exception.
+            1. If ? HasProperty(_temporalCalendarLike_, *"calendar"*) is *false*, return _temporalCalendarLike_.
         1. Let _identifier_ be ? ToString(_temporalCalendarLike_).
         1. Set _identifier_ to ? ParseTemporalCalendarString(_identifier_).
         1. If IsBuiltinCalendar(_identifier_) is *false*, throw a *RangeError* exception.

spec/timezone.html

@@ -539,9 +539,12 @@ <h1>ToTemporalTimeZone ( _temporalTimeZoneLike_ )</h1>
             1. Return _temporalTimeZoneLike_.
           1. If _temporalTimeZoneLike_ has an [[InitializedTemporalZonedDateTime]] internal slot, then
             1. Return _temporalTimeZoneLike_.[[TimeZone]].
+          1. If _temporalTimeZoneLike_ has an [[InitializedTemporalCalendar]] internal slot, throw a *RangeError* exception.
           1. If ? HasProperty(_temporalTimeZoneLike_, *"timeZone"*) is *false*, return _temporalTimeZoneLike_.
           1. Set _temporalTimeZoneLike_ to ? Get(_temporalTimeZoneLike_, *"timeZone"*).
-          1. If Type(_temporalTimeZoneLike_) is Object and ? HasProperty(_temporalTimeZoneLike_, *"timeZone"*) is *false*, return _temporalTimeZoneLike_.
+          1. If Type(_temporalTimeZoneLike_) is Object, then
+            1. If _temporalTimeZoneLike_ has an [[InitializedTemporalCalendar]] internal slot, throw a *RangeError* exception.
+            1. If ? HasProperty(_temporalTimeZoneLike_, *"timeZone"*) is *false*, return _temporalTimeZoneLike_.
         1. Let _identifier_ be ? ToString(_temporalTimeZoneLike_).
         1. Let _parseResult_ be ? ParseTemporalTimeZoneString(_identifier_).
         1. If _parseResult_.[[Name]] is not *undefined*, then