LibJS: Replace GetIANATimeZoneOffset[Ns] with GetNamedTimeZoneOffset[Ns]

This is an editorial change in the Temporal spec. See:
https://github.com/tc39/proposal-temporal/commit/e44d36b

3 files changed, 15 insertions, 48 deletions

diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.cpp
index 3230448e78..06ffecfe4b 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.cpp
@@ -149,39 +149,7 @@ ISODateTime get_iso_parts_from_epoch(VM& vm, Crypto::SignedBigInteger const& epo
     return { .year = year, .month = month, .day = day, .hour = hour, .minute = minute, .second = second, .millisecond = millisecond, .microsecond = static_cast<u16>(microsecond), .nanosecond = static_cast<u16>(nanosecond) };
 }
 
-// 11.6.3 GetIANATimeZoneOffsetNanoseconds ( epochNanoseconds, timeZoneIdentifier ), https://tc39.es/proposal-temporal/#sec-temporal-getianatimezoneoffsetnanoseconds
-i64 get_iana_time_zone_offset_nanoseconds(BigInt const& epoch_nanoseconds, String const& time_zone_identifier)
-{
-    // The implementation-defined abstract operation GetIANATimeZoneOffsetNanoseconds takes arguments epochNanoseconds (a BigInt) and timeZoneIdentifier (a String) and returns an integer.
-    // The returned integer represents the offset of the IANA time zone identified by timeZoneIdentifier from UTC, at the instant corresponding to epochNanoseconds.
-    // Given the same values of epochNanoseconds and timeZoneIdentifier, the result must be the same for the lifetime of the surrounding agent.
-
-    // Only called with validated TimeZone [[Identifier]] as argument.
-    auto time_zone = ::TimeZone::time_zone_from_string(time_zone_identifier);
-    VERIFY(time_zone.has_value());
-
-    // Since Time::from_seconds() and Time::from_nanoseconds() both take an i64, converting to
-    // seconds first gives us a greater range. The TZDB doesn't have sub-second offsets.
-    auto seconds = epoch_nanoseconds.big_integer().divided_by("1000000000"_bigint).quotient;
-
-    // The provided epoch (nano)seconds value is potentially out of range for AK::Time and subsequently
-    // get_time_zone_offset(). We can safely assume that the TZDB has no useful information that far
-    // into the past and future anyway, so clamp it to the i64 range.
-    Time time;
-    if (seconds < Crypto::SignedBigInteger { NumericLimits<i64>::min() })
-        time = Time::min();
-    else if (seconds > Crypto::SignedBigInteger { NumericLimits<i64>::max() })
-        time = Time::max();
-    else
-        time = Time::from_seconds(*seconds.to_base(10).to_int<i64>());
-
-    auto offset = ::TimeZone::get_time_zone_offset(*time_zone, time);
-    VERIFY(offset.has_value());
-
-    return offset->seconds * 1'000'000'000;
-}
-
-// 11.6.4 GetIANATimeZoneNextTransition ( epochNanoseconds, timeZoneIdentifier ), https://tc39.es/proposal-temporal/#sec-temporal-getianatimezonenexttransition
+// 11.6.3 GetIANATimeZoneNextTransition ( epochNanoseconds, timeZoneIdentifier ), https://tc39.es/proposal-temporal/#sec-temporal-getianatimezonenexttransition
 BigInt* get_iana_time_zone_next_transition(VM&, [[maybe_unused]] BigInt const& epoch_nanoseconds, [[maybe_unused]] StringView time_zone_identifier)
 {
     // The implementation-defined abstract operation GetIANATimeZoneNextTransition takes arguments epochNanoseconds (a BigInt) and timeZoneIdentifier (a String) and returns a BigInt or null.
@@ -192,7 +160,7 @@ BigInt* get_iana_time_zone_next_transition(VM&, [[maybe_unused]] BigInt const& e
     return nullptr;
 }
 
-// 11.6.5 GetIANATimeZonePreviousTransition ( epochNanoseconds, timeZoneIdentifier ), https://tc39.es/proposal-temporal/#sec-temporal-getianatimezoneprevioustransition
+// 11.6.4 GetIANATimeZonePreviousTransition ( epochNanoseconds, timeZoneIdentifier ), https://tc39.es/proposal-temporal/#sec-temporal-getianatimezoneprevioustransition
 BigInt* get_iana_time_zone_previous_transition(VM&, [[maybe_unused]] BigInt const& epoch_nanoseconds, [[maybe_unused]] StringView time_zone_identifier)
 {
     // The implementation-defined abstract operation GetIANATimeZonePreviousTransition takes arguments epochNanoseconds (a BigInt) and timeZoneIdentifier (a String) and returns a BigInt or null.
@@ -246,7 +214,7 @@ bool is_valid_time_zone_numeric_utc_offset_syntax(String const& offset_string)
     return parse_time_zone_numeric_utc_offset_syntax(offset_string, discarded, discarded, optionally_discarded, optionally_discarded, optionally_discarded);
 }
 
-// 11.6.6 ParseTimeZoneOffsetString ( offsetString ), https://tc39.es/proposal-temporal/#sec-temporal-parsetimezoneoffsetstring
+// 11.6.5 ParseTimeZoneOffsetString ( offsetString ), https://tc39.es/proposal-temporal/#sec-temporal-parsetimezoneoffsetstring
 ThrowCompletionOr<double> parse_time_zone_offset_string(VM& vm, String const& offset_string)
 {
     // 1. Let parseResult be ParseText(StringToCodePoints(offsetString), TimeZoneNumericUTCOffset).
@@ -319,7 +287,7 @@ ThrowCompletionOr<double> parse_time_zone_offset_string(VM& vm, String const& of
     return factor * (((hours_mv * 60 + minutes_mv) * 60 + seconds_mv) * 1e9 + nanoseconds_mv);
 }
 
-// 11.6.7 FormatTimeZoneOffsetString ( offsetNanoseconds ), https://tc39.es/proposal-temporal/#sec-temporal-formattimezoneoffsetstring
+// 11.6.6 FormatTimeZoneOffsetString ( offsetNanoseconds ), https://tc39.es/proposal-temporal/#sec-temporal-formattimezoneoffsetstring
 String format_time_zone_offset_string(double offset_nanoseconds)
 {
     auto offset = static_cast<i64>(offset_nanoseconds);
@@ -373,7 +341,7 @@ String format_time_zone_offset_string(double offset_nanoseconds)
     return builder.to_string();
 }
 
-// 11.6.8 FormatISOTimeZoneOffsetString ( offsetNanoseconds ), https://tc39.es/proposal-temporal/#sec-temporal-formatisotimezoneoffsetstring
+// 11.6.7 FormatISOTimeZoneOffsetString ( offsetNanoseconds ), https://tc39.es/proposal-temporal/#sec-temporal-formatisotimezoneoffsetstring
 String format_iso_time_zone_offset_string(double offset_nanoseconds)
 {
     // 1. Assert: offsetNanoseconds is an integer.
@@ -400,7 +368,7 @@ String format_iso_time_zone_offset_string(double offset_nanoseconds)
     return String::formatted("{}{:02}:{:02}", sign, (u32)hours, (u32)minutes);
 }
 
-// 11.6.9 ToTemporalTimeZone ( temporalTimeZoneLike ), https://tc39.es/proposal-temporal/#sec-temporal-totemporaltimezone
+// 11.6.8 ToTemporalTimeZone ( temporalTimeZoneLike ), https://tc39.es/proposal-temporal/#sec-temporal-totemporaltimezone
 ThrowCompletionOr<Object*> to_temporal_time_zone(VM& vm, Value temporal_time_zone_like)
 {
     // 1. If Type(temporalTimeZoneLike) is Object, then
@@ -458,7 +426,7 @@ ThrowCompletionOr<Object*> to_temporal_time_zone(VM& vm, Value temporal_time_zon
     return MUST(create_temporal_time_zone(vm, *parse_result.offset_string));
 }
 
-// 11.6.10 GetOffsetNanosecondsFor ( timeZone, instant ), https://tc39.es/proposal-temporal/#sec-temporal-getoffsetnanosecondsfor
+// 11.6.9 GetOffsetNanosecondsFor ( timeZone, instant ), https://tc39.es/proposal-temporal/#sec-temporal-getoffsetnanosecondsfor
 ThrowCompletionOr<double> get_offset_nanoseconds_for(VM& vm, Value time_zone, Instant& instant)
 {
     // 1. Let getOffsetNanosecondsFor be ? GetMethod(timeZone, "getOffsetNanosecondsFor").
@@ -486,7 +454,7 @@ ThrowCompletionOr<double> get_offset_nanoseconds_for(VM& vm, Value time_zone, In
     return offset_nanoseconds;
 }
 
-// 11.6.11 BuiltinTimeZoneGetOffsetStringFor ( timeZone, instant ), https://tc39.es/proposal-temporal/#sec-temporal-builtintimezonegetoffsetstringfor
+// 11.6.10 BuiltinTimeZoneGetOffsetStringFor ( timeZone, instant ), https://tc39.es/proposal-temporal/#sec-temporal-builtintimezonegetoffsetstringfor
 ThrowCompletionOr<String> builtin_time_zone_get_offset_string_for(VM& vm, Value time_zone, Instant& instant)
 {
     // 1. Let offsetNanoseconds be ? GetOffsetNanosecondsFor(timeZone, instant).
@@ -496,7 +464,7 @@ ThrowCompletionOr<String> builtin_time_zone_get_offset_string_for(VM& vm, Value
     return format_time_zone_offset_string(offset_nanoseconds);
 }
 
-// 11.6.12 BuiltinTimeZoneGetPlainDateTimeFor ( timeZone, instant, calendar ), https://tc39.es/proposal-temporal/#sec-temporal-builtintimezonegetplaindatetimefor
+// 11.6.11 BuiltinTimeZoneGetPlainDateTimeFor ( timeZone, instant, calendar ), https://tc39.es/proposal-temporal/#sec-temporal-builtintimezonegetplaindatetimefor
 ThrowCompletionOr<PlainDateTime*> builtin_time_zone_get_plain_date_time_for(VM& vm, Value time_zone, Instant& instant, Object& calendar)
 {
     // 1. Assert: instant has an [[InitializedTemporalInstant]] internal slot.
@@ -514,7 +482,7 @@ ThrowCompletionOr<PlainDateTime*> builtin_time_zone_get_plain_date_time_for(VM&
     return create_temporal_date_time(vm, result.year, result.month, result.day, result.hour, result.minute, result.second, result.millisecond, result.microsecond, result.nanosecond, calendar);
 }
 
-// 11.6.13 BuiltinTimeZoneGetInstantFor ( timeZone, dateTime, disambiguation ), https://tc39.es/proposal-temporal/#sec-temporal-builtintimezonegetinstantfor
+// 11.6.12 BuiltinTimeZoneGetInstantFor ( timeZone, dateTime, disambiguation ), https://tc39.es/proposal-temporal/#sec-temporal-builtintimezonegetinstantfor
 ThrowCompletionOr<Instant*> builtin_time_zone_get_instant_for(VM& vm, Value time_zone, PlainDateTime& date_time, StringView disambiguation)
 {
     // 1. Assert: dateTime has an [[InitializedTemporalDateTime]] internal slot.
@@ -526,7 +494,7 @@ ThrowCompletionOr<Instant*> builtin_time_zone_get_instant_for(VM& vm, Value time
     return disambiguate_possible_instants(vm, possible_instants, time_zone, date_time, disambiguation);
 }
 
-// 11.6.14 DisambiguatePossibleInstants ( possibleInstants, timeZone, dateTime, disambiguation ), https://tc39.es/proposal-temporal/#sec-temporal-disambiguatepossibleinstants
+// 11.6.13 DisambiguatePossibleInstants ( possibleInstants, timeZone, dateTime, disambiguation ), https://tc39.es/proposal-temporal/#sec-temporal-disambiguatepossibleinstants
 ThrowCompletionOr<Instant*> disambiguate_possible_instants(VM& vm, MarkedVector<Instant*> const& possible_instants, Value time_zone, PlainDateTime& date_time, StringView disambiguation)
 {
     // 1. Assert: dateTime has an [[InitializedTemporalDateTime]] internal slot.
@@ -644,7 +612,7 @@ ThrowCompletionOr<Instant*> disambiguate_possible_instants(VM& vm, MarkedVector<
     return possible_instants_[n - 1];
 }
 
-// 11.6.15 GetPossibleInstantsFor ( timeZone, dateTime ), https://tc39.es/proposal-temporal/#sec-temporal-getpossibleinstantsfor
+// 11.6.14 GetPossibleInstantsFor ( timeZone, dateTime ), https://tc39.es/proposal-temporal/#sec-temporal-getpossibleinstantsfor
 ThrowCompletionOr<MarkedVector<Instant*>> get_possible_instants_for(VM& vm, Value time_zone, PlainDateTime& date_time)
 {
     // 1. Assert: dateTime has an [[InitializedTemporalDateTime]] internal slot.
@@ -689,7 +657,7 @@ ThrowCompletionOr<MarkedVector<Instant*>> get_possible_instants_for(VM& vm, Valu
     return { move(list) };
 }
 
-// 11.6.16 TimeZoneEquals ( one, two ), https://tc39.es/proposal-temporal/#sec-temporal-timezoneequals
+// 11.6.15 TimeZoneEquals ( one, two ), https://tc39.es/proposal-temporal/#sec-temporal-timezoneequals
 ThrowCompletionOr<bool> time_zone_equals(VM& vm, Object& one, Object& two)
 {
     // 1. If one and two are the same Object value, return true.
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.h b/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.h
index 89c36ad18f..929d662b0f 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.h
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.h
@@ -41,7 +41,6 @@ String canonicalize_time_zone_name(String const& time_zone);
 String default_time_zone();
 ThrowCompletionOr<TimeZone*> create_temporal_time_zone(VM&, String const& identifier, FunctionObject const* new_target = nullptr);
 ISODateTime get_iso_parts_from_epoch(VM&, Crypto::SignedBigInteger const& epoch_nanoseconds);
-i64 get_iana_time_zone_offset_nanoseconds(BigInt const& epoch_nanoseconds, String const& time_zone_identifier);
 BigInt* get_iana_time_zone_next_transition(VM&, BigInt const& epoch_nanoseconds, StringView time_zone_identifier);
 BigInt* get_iana_time_zone_previous_transition(VM&, BigInt const& epoch_nanoseconds, StringView time_zone_identifier);
 ThrowCompletionOr<double> parse_time_zone_offset_string(VM&, String const&);
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/TimeZonePrototype.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/TimeZonePrototype.cpp
index 1997ee8135..d1995a0247 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/TimeZonePrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/TimeZonePrototype.cpp
@@ -70,8 +70,8 @@ JS_DEFINE_NATIVE_FUNCTION(TimeZonePrototype::get_offset_nanoseconds_for)
     if (time_zone->offset_nanoseconds().has_value())
         return Value(*time_zone->offset_nanoseconds());
 
-    // 5. Return 𝔽(GetIANATimeZoneOffsetNanoseconds(instant.[[Nanoseconds]], timeZone.[[Identifier]])).
-    return Value((double)get_iana_time_zone_offset_nanoseconds(instant->nanoseconds(), time_zone->identifier()));
+    // 5. Return 𝔽(GetNamedTimeZoneOffsetNanoseconds(timeZone.[[Identifier]], instant.[[Nanoseconds]])).
+    return Value((double)get_named_time_zone_offset_nanoseconds(time_zone->identifier(), instant->nanoseconds().big_integer()));
 }
 
 // 11.4.5 Temporal.TimeZone.prototype.getOffsetStringFor ( instant ), https://tc39.es/proposal-temporal/#sec-temporal.timezone.prototype.getoffsetstringfor