From 1a23f2c9f2c044ea0053b064e30bb44a5e200cf0 Mon Sep 17 00:00:00 2001
From: Philip Chimento <pchimento@igalia.com>
Date: Mon, 7 Oct 2024 11:26:34 -0700
Subject: [PATCH] Editorial: Return ISO Date-Time Record from SystemDateTime

This avoids creation of an unobservable Temporal.PlainDateTime object, and
is also simpler to read.

See: #2949
---
 polyfill/lib/now.mjs | 15 +++++++++++----
 spec/temporal.html   | 16 ++++++++--------
 2 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/polyfill/lib/now.mjs b/polyfill/lib/now.mjs
index 1c5177fa6..e36c56838 100644
--- a/polyfill/lib/now.mjs
+++ b/polyfill/lib/now.mjs
@@ -2,7 +2,10 @@ import { ObjectDefineProperty, SymbolToStringTag } from './primordials.mjs';
 
 import * as ES from './ecmascript.mjs';
 import { GetIntrinsic } from './intrinsicclass.mjs';
-import { GetSlot, ISO_DATE_TIME } from './slots.mjs';
+
+function SystemDateTime(timeZone) {
+  return ES.GetISODateTimeFor(timeZone, ES.SystemUTCEpochNanoSeconds());
+}
 
 const instant = () => {
   const Instant = GetIntrinsic('%Temporal.Instant%');
@@ -10,7 +13,7 @@ const instant = () => {
 };
 const plainDateTimeISO = (temporalTimeZoneLike = ES.DefaultTimeZone()) => {
   const timeZone = ES.ToTemporalTimeZoneIdentifier(temporalTimeZoneLike);
-  const isoDateTime = ES.GetISODateTimeFor(timeZone, ES.SystemUTCEpochNanoSeconds());
+  const isoDateTime = SystemDateTime(timeZone);
   return ES.CreateTemporalDateTime(isoDateTime, 'iso8601');
 };
 const zonedDateTimeISO = (temporalTimeZoneLike = ES.DefaultTimeZone()) => {
@@ -18,10 +21,14 @@ const zonedDateTimeISO = (temporalTimeZoneLike = ES.DefaultTimeZone()) => {
   return ES.CreateTemporalZonedDateTime(ES.SystemUTCEpochNanoSeconds(), timeZone, 'iso8601');
 };
 const plainDateISO = (temporalTimeZoneLike = ES.DefaultTimeZone()) => {
-  return ES.CreateTemporalDate(GetSlot(plainDateTimeISO(temporalTimeZoneLike), ISO_DATE_TIME).isoDate, 'iso8601');
+  const timeZone = ES.ToTemporalTimeZoneIdentifier(temporalTimeZoneLike);
+  const isoDateTime = SystemDateTime(timeZone);
+  return ES.CreateTemporalDate(isoDateTime.isoDate, 'iso8601');
 };
 const plainTimeISO = (temporalTimeZoneLike = ES.DefaultTimeZone()) => {
-  return ES.CreateTemporalTime(GetSlot(plainDateTimeISO(temporalTimeZoneLike), ISO_DATE_TIME).time);
+  const timeZone = ES.ToTemporalTimeZoneIdentifier(temporalTimeZoneLike);
+  const isoDateTime = SystemDateTime(timeZone);
+  return ES.CreateTemporalTime(isoDateTime.time);
 };
 const timeZoneId = () => {
   return ES.DefaultTimeZone();
diff --git a/spec/temporal.html b/spec/temporal.html
index 6abd348f6..737c19c23 100644
--- a/spec/temporal.html
+++ b/spec/temporal.html
@@ -122,7 +122,8 @@ <h1>Temporal.Now.instant ( )</h1>
       <h1>Temporal.Now.plainDateTimeISO ( [ _temporalTimeZoneLike_ ] )</h1>
       <p>This function performs the following steps when called:</p>
       <emu-alg>
-        1. Return ? SystemDateTime(_temporalTimeZoneLike_).
+        1. Let _isoDateTime_ be ? SystemDateTime(_temporalTimeZoneLike_).
+        1. Return ! CreateTemporalDateTime(_isoDateTime_, *"iso8601"*).
       </emu-alg>
     </emu-clause>
 
@@ -138,8 +139,8 @@ <h1>Temporal.Now.zonedDateTimeISO ( [ _temporalTimeZoneLike_ ] )</h1>
       <h1>Temporal.Now.plainDateISO ( [ _temporalTimeZoneLike_ ] )</h1>
       <p>This function performs the following steps when called:</p>
       <emu-alg>
-        1. Let _dateTime_ be ? SystemDateTime(_temporalTimeZoneLike_).
-        1. Return ! CreateTemporalDate(_dateTime_.[[ISODateTime]].[[ISODate]], *"iso8601"*).
+        1. Let _isoDateTime_ be ? SystemDateTime(_temporalTimeZoneLike_).
+        1. Return ! CreateTemporalDate(_isoDateTime_.[[ISODate]], *"iso8601"*).
       </emu-alg>
     </emu-clause>
 
@@ -147,8 +148,8 @@ <h1>Temporal.Now.plainDateISO ( [ _temporalTimeZoneLike_ ] )</h1>
       <h1>Temporal.Now.plainTimeISO ( [ _temporalTimeZoneLike_ ] )</h1>
       <p>This function performs the following steps when called:</p>
       <emu-alg>
-        1. Let _dateTime_ be ? SystemDateTime(_temporalTimeZoneLike_).
-        1. Return ! CreateTemporalTime(_dateTime_.[[ISODateTime]].[[Time]]).
+        1. Let _isoDateTime_ be ? SystemDateTime(_temporalTimeZoneLike_).
+        1. Return ! CreateTemporalTime(_isoDateTime_.[[Time]]).
       </emu-alg>
     </emu-clause>
   </emu-clause>
@@ -230,7 +231,7 @@ <h1>SystemInstant ( ): a Temporal.Instant</h1>
       <h1>
         SystemDateTime (
           _temporalTimeZoneLike_: an ECMAScript language value,
-        ): either a normal completion containing a Temporal.PlainDateTime or a throw completion
+        ): either a normal completion containing an ISO Date-Time Record or a throw completion
       </h1>
       <dl class="header">
         <dt>description</dt>
@@ -242,8 +243,7 @@ <h1>
         1. Else,
           1. Let _timeZone_ be ? ToTemporalTimeZoneIdentifier(_temporalTimeZoneLike_).
         1. Let _epochNs_ be SystemUTCEpochNanoseconds().
-        1. Let _isoDateTime_ be GetISODateTimeFor(_timeZone_, _epochNs_).
-        1. Return ! CreateTemporalDateTime(_isoDateTime_, *"iso8601"*).
+        1. Return GetISODateTimeFor(_timeZone_, _epochNs_).
       </emu-alg>
     </emu-clause>