Editorial: Fix numeric type confusion in return value of GetEpochFromISOParts

Some existing algorithms treated this as a BigInt and some as a
mathematical value. It's really six of one, half a dozen of the other,
which is more convenient. I chose BigInt because that fits with the
internal EpochNanoseconds slot of Instant and ZonedDateTime being a
BigInt.

Author: ptomato

spec/instant.html

@@ -545,11 +545,11 @@ <h1>ParseTemporalInstant ( _isoString_ )</h1>
         1. Let _offsetString_ be _result_.[[TimeZoneOffsetString]].
         1. Assert: _offsetString_ is not *undefined*.
         1. Let _utc_ be GetEpochFromISOParts(_result_.[[Year]], _result_.[[Month]], _result_.[[Day]], _result_.[[Hour]], _result_.[[Minute]], _result_.[[Second]], _result_.[[Millisecond]], _result_.[[Microsecond]], _result_.[[Nanosecond]]).
-        1. If _utc_ &lt; −8.64 × 10<sup>21</sup> or _utc_ &gt; 8.64 × 10<sup>21</sup>, then
+        1. If ℝ(_utc_) &lt; −8.64 × 10<sup>21</sup> or ℝ(_utc_) &gt; 8.64 × 10<sup>21</sup>, then
           1. Throw a *RangeError* exception.
         1. Let _offsetNanoseconds_ be ? ParseTimeZoneOffsetString(_offsetString_).
-        1. Let _result_ be _utc_ − _offsetNanoseconds_.
-        1. If ! IsValidEpochNanoseconds(ℤ(_result_)) is *false*, then
+        1. Let _result_ be _utc_ − ℤ(_offsetNanoseconds_).
+        1. If ! IsValidEpochNanoseconds(_result_) is *false*, then
           1. Throw a *RangeError* exception.
         1. Return _result_.
       </emu-alg>

spec/plaindatetime.html

@@ -864,7 +864,7 @@ <h1>
         1. Let _time_ be MakeTime(𝔽(_hour_), 𝔽(_minute_), 𝔽(_second_), 𝔽(_millisecond_)).
         1. Let _ms_ be MakeDate(_date_, _time_).
         1. Assert: _ms_ is finite.
-        1. Return ℝ(_ms_) × 10<sup>6</sup> + _microsecond_ × 10<sup>3</sup> + _nanosecond_.
+        1. Return ℤ(ℝ(_ms_) × 10<sup>6</sup> + _microsecond_ × 10<sup>3</sup> + _nanosecond_).
       </emu-alg>
     </emu-clause>
 
@@ -893,7 +893,7 @@ <h1>
         </p>
       </emu-note>
       <emu-alg>
-        1. Let _ns_ be GetEpochFromISOParts(_year_, _month_, _day_, _hour_, _minute_, _second_, _millisecond_, _microsecond_, _nanosecond_).
+        1. Let _ns_ be ℝ(GetEpochFromISOParts(_year_, _month_, _day_, _hour_, _minute_, _second_, _millisecond_, _microsecond_, _nanosecond_)).
         1. If _ns_ ≤ -8.64 × 10<sup>21</sup> - 8.64 × 10<sup>13</sup>, then
           1. Return *false*.
         1. If _ns_ ≥ 8.64 × 10<sup>21</sup> + 8.64 × 10<sup>13</sup>, then

spec/timezone.html

@@ -281,7 +281,7 @@ <h1>Temporal.TimeZone.prototype.getPossibleInstantsFor ( _dateTime_ )</h1>
         1. Set _dateTime_ to ? ToTemporalDateTime(_dateTime_).
         1. If _timeZone_.[[OffsetNanoseconds]] is not *undefined*, then
           1. Let _epochNanoseconds_ be GetEpochFromISOParts(_dateTime_.[[ISOYear]], _dateTime_.[[ISOMonth]], _dateTime_.[[ISODay]], _dateTime_.[[ISOHour]], _dateTime_.[[ISOMinute]], _dateTime_.[[ISOSecond]], _dateTime_.[[ISOMillisecond]], _dateTime_.[[ISOMicrosecond]], _dateTime_.[[ISONanosecond]]).
-          1. Let _instant_ be ! CreateTemporalInstant(ℤ(_epochNanoseconds_ − _timeZone_.[[OffsetNanoseconds]])).
+          1. Let _instant_ be ! CreateTemporalInstant(_epochNanoseconds_ − ℤ(_timeZone_.[[OffsetNanoseconds]])).
           1. Return CreateArrayFromList(« _instant_ »).
         1. Let _possibleEpochNanoseconds_ be GetIANATimeZoneEpochValue(_timeZone_.[[Identifier]], _dateTime_.[[ISOYear]], _dateTime_.[[ISOMonth]], _dateTime_.[[ISODay]], _dateTime_.[[ISOHour]], _dateTime_.[[ISOMinute]], _dateTime_.[[ISOSecond]], _dateTime_.[[ISOMillisecond]], _dateTime_.[[ISOMicrosecond]], _dateTime_.[[ISONanosecond]]).
         1. Let _possibleInstants_ be a new empty List.
@@ -698,8 +698,8 @@ <h1>DisambiguatePossibleInstants ( _possibleInstants_, _timeZone_, _dateTime_, _
         1. If _disambiguation_ is *"reject"*, then
           1. Throw a *RangeError* exception.
         1. Let _epochNanoseconds_ be GetEpochFromISOParts(_dateTime_.[[ISOYear]], _dateTime_.[[ISOMonth]], _dateTime_.[[ISODay]], _dateTime_.[[ISOHour]], _dateTime_.[[ISOMinute]], _dateTime_.[[ISOSecond]], _dateTime_.[[ISOMillisecond]], _dateTime_.[[ISOMicrosecond]], _dateTime_.[[ISONanosecond]]).
-        1. Let _dayBefore_ be ! CreateTemporalInstant(_epochNanoseconds_ − 8.64 × 10<sup>13</sup>).
-        1. Let _dayAfter_ be ! CreateTemporalInstant(_epochNanoseconds_ + 8.64 × 10<sup>13</sup>).
+        1. Let _dayBefore_ be ! CreateTemporalInstant(_epochNanoseconds_ − *8.64 × 10<sup>13</sup>*<sub>ℤ</sub>).
+        1. Let _dayAfter_ be ! CreateTemporalInstant(_epochNanoseconds_ + *8.64 × 10<sup>13</sup>*<sub>ℤ</sub>).
         1. Let _offsetBefore_ be ? GetOffsetNanosecondsFor(_timeZone_, _dayBefore_).
         1. Let _offsetAfter_ be ? GetOffsetNanosecondsFor(_timeZone_, _dayAfter_).
         1. Let _nanoseconds_ be _offsetAfter_ − _offsetBefore_.

spec/zoneddatetime.html

@@ -1119,7 +1119,7 @@ <h1>
           1. Return _instant_.[[Nanoseconds]].
         1. If _offsetBehaviour_ is ~exact~, or _offsetOption_ is *"use"*, then
           1. Let _epochNanoseconds_ be GetEpochFromISOParts(_year_, _month_, _day_, _hour_, _minute_, _second_, _millisecond_, _microsecond_, _nanosecond_).
-          1. Return _epochNanoseconds_ − _offsetNanoseconds_.
+          1. Return _epochNanoseconds_ − ℤ(_offsetNanoseconds_).
         1. Assert: _offsetBehaviour_ is ~option~.
         1. Assert: _offsetOption_ is *"prefer"* or *"reject"*.
         1. Let _possibleInstants_ be ? GetPossibleInstantsFor(_timeZone_, _dateTime_).