Make Calendar.id optional on plain objects, to align with TimeZone.id

We have TimeZone.id optional on plain objects, in favour of requiring TimeZone.toString(). The calendar protocol should do the same thing.
tc39 · Oct 22, 2020 · df5d81c · df5d81c
1 parent 14ba0a4
commit df5d81c
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diff --git a/docs/calendar.md b/docs/calendar.md
@@ -46,7 +46,7 @@ The identifier of a custom calendar must consist of one or more components of be
 ### Protocol
 
 It's also possible for a plain object to be a custom calendar, without subclassing.
-The object must implement the `Temporal.Calendar` methods and have an `id` property.
+The object must implement all of the `Temporal.Calendar` methods except for `fields()`.
 It must not have a `calendar` property, so that it can be distinguished in `Temporal.Calendar.from()` from other Temporal objects that have a calendar.
 It is possible to pass such an object into any Temporal API that would normally take a built-in `Temporal.Calendar`.
 

diff --git a/polyfill/index.d.ts b/polyfill/index.d.ts
@@ -430,7 +430,7 @@ export namespace Temporal {
   }
 
   export interface CalendarProtocol {
-    id: string;
+    id?: string;
     calendar?: never;
     year(date: Temporal.Date): number;
     month(date: Temporal.Date): number;
@@ -484,6 +484,7 @@ export namespace Temporal {
         | /** @deprecated */ 'day'
       >
     ): Temporal.Duration;
+    toString(): string;
   }
 
   /**