Enable parsing of strings without offsets per tc39#933

polyfill/lib/poc/ZonedDateTime.test.ts

@@ -87,6 +87,14 @@ describe('ZonedDateTime', () => {
       const zdt = Temporal.ZonedDateTime.from('2020-03-08T01:00-08:00[America/Los_Angeles]');
       equal(zdt.toString(), '2020-03-08T01:00-08:00[America/Los_Angeles]');
     });
+    it('parses with an IANA zone but no offset', () => {
+      const zdt = Temporal.ZonedDateTime.from('2020-03-08T01:00[America/Los_Angeles]');
+      equal(zdt.toString(), '2020-03-08T01:00-08:00[America/Los_Angeles]');
+    });
+    it('parses with an IANA zone but no offset (with disambiguation)', () => {
+      const zdt = Temporal.ZonedDateTime.from('2020-03-08T02:30[America/Los_Angeles]', { disambiguation: 'earlier' });
+      equal(zdt.toString(), '2020-03-08T01:30-08:00[America/Los_Angeles]');
+    });
     it('parses with an offset in brackets', () => {
       const zdt = Temporal.ZonedDateTime.from('2020-03-08T01:00-08:00[-08:00]');
       equal(zdt.toString(), '2020-03-08T01:00-08:00[-08:00]');

polyfill/lib/poc/ZonedDateTime.ts

@@ -119,9 +119,18 @@ function fromIsoString(isoString: string, options?: ZonedDateTimeAssignmentOptio
   // > time zone. (So you can't tell what the local time will be one minute
   // > later, for example.)
   const isZ = absString.trimEnd().toUpperCase().endsWith('Z');
-  const abs = Temporal.Instant.from(absString);
+  let abs: Temporal.Instant;
+  let ignoreOffsetOption = isZ;
+  try {
+    abs = Temporal.Instant.from(absString);
+  } catch (e) {
+    // presumably, parsing to Instant failed because offset is missing,
+    // so we'll just infer the offset from the time zone.
+    abs = dt.toInstant(tz, { disambiguation });
+    ignoreOffsetOption = true;
+  }
   const offsetNs = dt.difference(abs.toDateTime('UTC', dt.calendar), { largestUnit: 'nanoseconds' }).nanoseconds;
-  return fromCommon(dt.withCalendar(cal), tz, offsetNs, disambiguation, isZ ? 'use' : offsetOption);
+  return fromCommon(dt.withCalendar(cal), tz, offsetNs, disambiguation, ignoreOffsetOption ? 'use' : offsetOption);
 }
 
 /** Shared logic for the object and string forms of `from` */

polyfill/lib/zoneddatetime.mjs

@@ -79,9 +79,18 @@ function fromIsoString(isoString, options) {
   // > time zone. (So you can't tell what the local time will be one minute
   // > later, for example.)
   const isZ = absString.trimEnd().toUpperCase().endsWith('Z');
-  const abs = Temporal.Instant.from(absString);
+  let abs;
+  let ignoreOffsetOption = isZ;
+  try {
+    abs = Temporal.Instant.from(absString);
+  } catch (e) {
+    // presumably, parsing to Instant failed because offset is missing,
+    // so we'll just infer the offset from the time zone.
+    abs = dt.toInstant(tz, { disambiguation });
+    ignoreOffsetOption = true;
+  }
   const offsetNs = dt.difference(abs.toDateTime('UTC', dt.calendar), { largestUnit: 'nanoseconds' }).nanoseconds;
-  return fromCommon(dt.withCalendar(cal), tz, offsetNs, disambiguation, isZ ? 'use' : offsetOption);
+  return fromCommon(dt.withCalendar(cal), tz, offsetNs, disambiguation, ignoreOffsetOption ? 'use' : offsetOption);
 }
 
 /** Shared logic for the object and string forms of `from` */

polyfill/poc.d.ts

@@ -348,6 +348,7 @@ export namespace Temporal {
 
   export interface CalendarProtocol {
     id: string;
+    calendar?: never;
     year(date: Temporal.Date): number;
     month(date: Temporal.Date): number;
     day(date: Temporal.Date): number;
@@ -410,7 +411,7 @@ export namespace Temporal {
    *
    * See https://tc39.es/proposal-temporal/docs/calendar.html for more details.
    */
-  export class Calendar implements Required<CalendarProtocol> {
+  export class Calendar implements Omit<Required<CalendarProtocol>, 'calendar'> {
     static from(item: CalendarProtocol | string): Temporal.Calendar;
     constructor(calendarIdentifier: string);
     readonly id: string;
@@ -519,7 +520,7 @@ export namespace Temporal {
     readonly monthsInYear: number;
     readonly isLeapYear: boolean;
     equals(other: Temporal.Date): boolean;
-    with(dateLike: DateLike, options?: AssignmentOptions): Temporal.Date;
+    with(dateLike: DateLike | string, options?: AssignmentOptions): Temporal.Date;
     withCalendar(calendar: CalendarProtocol | string): Temporal.Date;
     add(durationLike: Temporal.Duration | DurationLike, options?: ArithmeticOptions): Temporal.Date;
     subtract(durationLike: Temporal.Duration | DurationLike, options?: ArithmeticOptions): Temporal.Date;
@@ -636,7 +637,7 @@ export namespace Temporal {
     readonly monthsInYear: number;
     readonly isLeapYear: boolean;
     equals(other: Temporal.DateTime): boolean;
-    with(dateTimeLike: DateTimeLike, options?: AssignmentOptions): Temporal.DateTime;
+    with(dateTimeLike: DateTimeLike | string, options?: AssignmentOptions): Temporal.DateTime;
     withCalendar(calendar: CalendarProtocol | string): Temporal.DateTime;
     add(durationLike: Temporal.Duration | DurationLike, options?: ArithmeticOptions): Temporal.DateTime;
     subtract(durationLike: Temporal.Duration | DurationLike, options?: ArithmeticOptions): Temporal.DateTime;
@@ -781,7 +782,7 @@ export namespace Temporal {
     readonly microsecond: number;
     readonly nanosecond: number;
     equals(other: Temporal.Time): boolean;
-    with(timeLike: Temporal.Time | TimeLike, options?: AssignmentOptions): Temporal.Time;
+    with(timeLike: TimeLike | string, options?: AssignmentOptions): Temporal.Time;
     add(durationLike: Temporal.Duration | DurationLike, options?: ArithmeticOptions): Temporal.Time;
     subtract(durationLike: Temporal.Duration | DurationLike, options?: ArithmeticOptions): Temporal.Time;
     difference(
@@ -834,6 +835,7 @@ export namespace Temporal {
    */
   export interface TimeZoneProtocol {
     id: string;
+    timeZone?: never;
     getOffsetNanosecondsFor(instant: Temporal.Instant): number;
     getOffsetStringFor(instant: Temporal.Instant): string;
     getZonedDateTimeFor(instant: Temporal.Instant, calendar?: CalendarProtocol | string): Temporal.ZonedDateTime;
@@ -859,8 +861,8 @@ export namespace Temporal {
    *
    * See https://tc39.es/proposal-temporal/docs/timezone.html for more details.
    */
-  export class TimeZone implements Required<TimeZoneProtocol> {
-    static from(timeZone: Temporal.TimeZoneProtocol | string): Temporal.TimeZone;
+  export class TimeZone implements Omit<Required<TimeZoneProtocol>, 'timeZone'> {
+    static from(timeZone: Temporal.TimeZone | string): Temporal.TimeZone;
     constructor(timeZoneIdentifier: string);
     readonly id: string;
     getOffsetNanosecondsFor(instant: Temporal.Instant): number;

polyfill/test/zoneddatetime.mjs

@@ -75,6 +75,14 @@ describe('ZonedDateTime', () => {
       const zdt = Temporal.ZonedDateTime.from('2020-03-08T01:00-08:00[America/Los_Angeles]');
       equal(zdt.toString(), '2020-03-08T01:00-08:00[America/Los_Angeles]');
     });
+    it('parses with an IANA zone but no offset', () => {
+      const zdt = Temporal.ZonedDateTime.from('2020-03-08T01:00[America/Los_Angeles]');
+      equal(zdt.toString(), '2020-03-08T01:00-08:00[America/Los_Angeles]');
+    });
+    it('parses with an IANA zone but no offset (with disambiguation)', () => {
+      const zdt = Temporal.ZonedDateTime.from('2020-03-08T02:30[America/Los_Angeles]', { disambiguation: 'earlier' });
+      equal(zdt.toString(), '2020-03-08T01:30-08:00[America/Los_Angeles]');
+    });
     it('parses with an offset in brackets', () => {
       const zdt = Temporal.ZonedDateTime.from('2020-03-08T01:00-08:00[-08:00]');
       equal(zdt.toString(), '2020-03-08T01:00-08:00[-08:00]');