fixup! Normative: Precalculate PlainDateTime from ZonedDateTime in mo…

…re places
tc39 · Sep 28, 2023 · a2239a8 · a2239a8
1 parent 817a3d7
commit a2239a8
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Showing 2 changed files with 16 additions and 7 deletions.
diff --git a/polyfill/lib/ecmascript.mjs b/polyfill/lib/ecmascript.mjs
@@ -3535,19 +3535,27 @@ export function BalancePossiblyInfiniteTimeDurationRelative(
   precalculatedPlainDateTime
 ) {
   const startNs = GetSlot(zonedRelativeTo, EPOCHNANOSECONDS);
+  const startInstant = GetSlot(zonedRelativeTo, INSTANT);
+  const timeZone = GetSlot(zonedRelativeTo, TIME_ZONE);
 
   let intermediateNs = startNs;
   if (days !== 0) {
-    const startInstant = GetSlot(zonedRelativeTo, INSTANT);
-    const timeZone = GetSlot(zonedRelativeTo, TIME_ZONE);
-    const startDt = precalculatedPlainDateTime ?? GetPlainDateTimeFor(timeZone, startInstant, 'iso8601');
-    intermediateNs = AddDaysToZonedDateTime(startInstant, startDt, timeZone, 'iso8601', days, 'constrain').epochNs;
+    precalculatedPlainDateTime ??= GetPlainDateTimeFor(timeZone, startInstant, 'iso8601');
+    intermediateNs = AddDaysToZonedDateTime(
+      startInstant,
+      precalculatedPlainDateTime,
+      timeZone,
+      'iso8601',
+      days,
+      'constrain'
+    ).epochNs;
   }
 
   const endNs = AddInstant(intermediateNs, hours, minutes, seconds, milliseconds, microseconds, nanoseconds);
   nanoseconds = endNs.subtract(startNs);
 
   if (largestUnit === 'year' || largestUnit === 'month' || largestUnit === 'week' || largestUnit === 'day') {
+    if (!nanoseconds.isZero()) precalculatedPlainDateTime ??= GetPlainDateTimeFor(timeZone, startInstant, 'iso8601');
     ({ days, nanoseconds } = NanosecondsToDays(nanoseconds, zonedRelativeTo, precalculatedPlainDateTime));
     largestUnit = 'hour';
   } else {

diff --git a/spec/duration.html b/spec/duration.html
@@ -1344,14 +1344,15 @@ <h1>
       <emu-alg>
         1. If _precalculatedPlainDateTime_ is not present, let _precalculatedPlainDateTime_ be *undefined*.
         1. Let _intermediateNs_ be _zonedRelativeTo_.[[Nanoseconds]].
+        1. Let _startInstant_ be ! CreateTemporalInstant(_zonedRelativeTo_.[[Nanoseconds]]).
         1. If _days_ &ne; 0, then
-          1. Let _startInstant_ be ! CreateTemporalInstant(_zonedRelativeTo_.[[Nanoseconds]]).
-          1. If _precalculatedPlainDateTime_ is not *undefined*, let _startDateTime_ be _precalculatedPlainDateTime_; else let _startDateTime_ be ? GetPlainDateTimeFor(_zonedRelativeTo_.[[TimeZone]], _startInstant_, *"iso8601"*).
-          1. Let _intermediateResult_ be ? AddDaysToZonedDateTime(_startInstant_, _startDateTime_, _zonedRelativeTo_.[[TimeZone]], *"iso8601"*, _days_, *"constrain"*).
+          1. If _precalculatedPlainDateTime_ is *undefined*, set _precalculatedPlainDateTime_ to ? GetPlainDateTimeFor(_zonedRelativeTo_.[[TimeZone]], _startInstant_, *"iso8601"*).
+          1. Let _intermediateResult_ be ? AddDaysToZonedDateTime(_startInstant_, _precalculatedPlainDateTime_, _zonedRelativeTo_.[[TimeZone]], *"iso8601"*, _days_, *"constrain"*).
           1. Set _intermediateNs_ to _intermediateResult_.[[EpochNanoseconds]].
         1. Let _endNs_ be AddInstant(_intermediateNs_, _hours_, _minutes_, _seconds_, _milliseconds_, _microseconds_, _nanoseconds_).
         1. Set _nanoseconds_ to ℝ(_endNs_ - _zonedRelativeTo_.[[Nanoseconds]]).
         1. If _largestUnit_ is one of *"year"*, *"month"*, *"week"*, or *"day"*, then
+          1. If _nanoseconds_ &ne; 0 and _precalculatedPlainDateTime_ is *undefined*, set _precalculatedPlainDateTime_ to ? GetPlainDateTimeFor(_zonedRelativeTo_.[[TimeZone]], _startInstant_, *"iso8601"*).
           1. Let _result_ be ? NanosecondsToDays(_nanoseconds_, _zonedRelativeTo_, _precalculatedPlainDateTime_).
           1. Set _days_ to _result_.[[Days]].
           1. Set _largestUnit_ to *"hour"*.