Accommodate calendar-specific fields in non-ISO ...FromFields() methods

Previously, the spec hardcoded "era" and "eraYear" as extra fields that
should be accessed on the property bags passed to the dateFromFields(),
yearMonthFromFields(), and monthDayFromFields() methods of
Temporal.Calendar.

Instead, the extra fields should be obtained by consulting the calendar's
fields() method. (But not observably; we call CalendarDateFields which is
an implementation-defined AO.) This accommodates calendars that require
additional extra fields, beyond "era" and "eraYear".

UPSTREAM_COMMIT=e938a3ef41ff602878eb430d0612b3de61179615

Author: ptomato

lib/calendar.ts

@@ -22,10 +22,16 @@ import {
   SetSlot
 } from './slots';
 import type { Temporal } from '..';
-import type { BuiltinCalendarId, CalendarParams as Params, CalendarReturn as Return } from './internaltypes';
+import type {
+  BuiltinCalendarId,
+  CalendarParams as Params,
+  CalendarReturn as Return,
+  AnyTemporalKey
+} from './internaltypes';
 
 const ArrayIncludes = Array.prototype.includes;
 const ArrayPrototypePush = Array.prototype.push;
+const ArrayPrototypeSort = Array.prototype.sort;
 const IntlDateTimeFormat = globalThis.Intl.DateTimeFormat;
 const ArraySort = Array.prototype.sort;
 const MathAbs = Math.abs;
@@ -2283,12 +2289,9 @@ class NonIsoCalendar implements CalendarImpl {
   ): Temporal.PlainDate {
     const overflow = ES.ToTemporalOverflow(options);
     const cache = new OneObjectCache();
-    // Intentionally alphabetical
-    const fields = ES.PrepareTemporalFields(
-      fieldsParam,
-      ['day', 'era', 'eraYear', 'month', 'monthCode', 'year'],
-      ['day']
-    );
+    const fieldNames = this.fields(['day', 'month', 'monthCode', 'year']) as readonly AnyTemporalKey[];
+    ArrayPrototypeSort.call(fieldNames);
+    const fields = ES.PrepareTemporalFields(fieldsParam, fieldNames, []);
     const { year, month, day } = this.helper.calendarToIsoDate(fields, overflow, cache);
     const result = ES.CreateTemporalDate(year, month, day, calendar);
     cache.setObject(result);
@@ -2301,8 +2304,9 @@ class NonIsoCalendar implements CalendarImpl {
   ): Temporal.PlainYearMonth {
     const overflow = ES.ToTemporalOverflow(options);
     const cache = new OneObjectCache();
-    // Intentionally alphabetical
-    const fields = ES.PrepareTemporalFields(fieldsParam, ['era', 'eraYear', 'month', 'monthCode', 'year'], []);
+    const fieldNames = this.fields(['month', 'monthCode', 'year']) as readonly AnyTemporalKey[];
+    ArrayPrototypeSort.call(fieldNames);
+    const fields = ES.PrepareTemporalFields(fieldsParam, fieldNames, []);
     const { year, month, day } = this.helper.calendarToIsoDate({ ...fields, day: 1 }, overflow, cache);
     const result = ES.CreateTemporalYearMonth(year, month, calendar, /* referenceISODay = */ day);
     cache.setObject(result);
@@ -2314,16 +2318,12 @@ class NonIsoCalendar implements CalendarImpl {
     calendar: Temporal.Calendar
   ): Temporal.PlainMonthDay {
     const overflow = ES.ToTemporalOverflow(options);
-    // All built-in calendars require `day`, but some allow other fields to be
-    // substituted for `month`. And for lunisolar calendars, either `monthCode`
-    // or `year` must be provided because `month` is ambiguous without a year or
-    // a code.
     const cache = new OneObjectCache();
-    const fields = ES.PrepareTemporalFields(
-      fieldsParam,
-      ['day', 'era', 'eraYear', 'month', 'monthCode', 'year'],
-      ['day']
-    );
+    // For lunisolar calendars, either `monthCode` or `year` must be provided
+    // because `month` is ambiguous without a year or a code.
+    const fieldNames = this.fields(['day', 'month', 'monthCode', 'year']) as readonly AnyTemporalKey[];
+    ArrayPrototypeSort.call(fieldNames);
+    const fields = ES.PrepareTemporalFields(fieldsParam, fieldNames, []);
     const { year, month, day } = this.helper.monthDayFromFields(fields, overflow, cache);
     // `year` is a reference year where this month/day exists in this calendar
     const result = ES.CreateTemporalMonthDay(month, day, calendar, /* referenceISOYear = */ year);

lib/ecmascript.ts

@@ -40,7 +40,9 @@ import type {
   PlainDateTimeParams,
   PlainYearMonthParams,
   PrimitiveFieldsOf,
-  BuiltinCalendarId
+  BuiltinCalendarId,
+  Keys,
+  AnyTemporalKey
 } from './internaltypes';
 import { GetIntrinsic } from './intrinsicclass';
 import {
@@ -1213,11 +1215,6 @@ interface FieldPrepareOptions {
   emptySourceErrorMessage: string;
 }
 
-type AnyTemporalKey = Exclude<Keys<AnyTemporalLikeType>, symbol>;
-
-// Keys is a conditionally-mapped version of keyof
-type Keys<T> = T extends Record<string, unknown> ? keyof T : never;
-
 // Returns all potential owners from all Temporal Like-types for a given union
 // of keys in K.
 // e.g.

lib/internaltypes.d.ts

@@ -61,6 +61,11 @@ type AllTemporalLikeTypes = [
 ];
 export type AnyTemporalLikeType = AllTemporalLikeTypes[number];
 
+// Keys is a conditionally-mapped version of keyof
+export type Keys<T> = T extends Record<string, unknown> ? keyof T : never;
+
+export type AnyTemporalKey = Exclude<Keys<AnyTemporalLikeType>, symbol>;
+
 // The properties below are all the names of Temporal properties that can be set with `with`.
 // `timeZone` and `calendar` are not on the list because they have special methods to set them.