LibJS: Fix number types in GetISOPartsFromEpoch

This is an editorial change in the Temporal spec.

See: https://github.com/tc39/proposal-temporal/commit/c5b645d

This means we now have to pass a global object and construct a BigInt
object just for the assertion, but oh well. We might want to have an
assertion macro that's optimized away in release builds at a later
point, however.

2 files changed, 17 insertions, 14 deletions

diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.cpp
index 854e15c4ee..521d463ce8 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.cpp
@@ -100,37 +100,40 @@ ThrowCompletionOr<TimeZone*> create_temporal_time_zone(GlobalObject& global_obje
 }
 
 // 11.6.2 GetISOPartsFromEpoch ( epochNanoseconds ), https://tc39.es/proposal-temporal/#sec-temporal-getisopartsfromepoch
-ISODateTime get_iso_parts_from_epoch(BigInt const& epoch_nanoseconds)
+ISODateTime get_iso_parts_from_epoch(GlobalObject& global_object, Crypto::SignedBigInteger const& epoch_nanoseconds)
 {
-    // 1. Assert: epochNanoseconds is an integer.
+    auto& vm = global_object.vm();
+
+    // 1. Assert: ! IsValidEpochNanoseconds(ℤ(epochNanoseconds)) is true.
+    VERIFY(is_valid_epoch_nanoseconds(*js_bigint(vm, epoch_nanoseconds)));
 
     // 2. Let remainderNs be epochNanoseconds modulo 10^6.
-    auto remainder_ns_bigint = modulo(epoch_nanoseconds.big_integer(), Crypto::UnsignedBigInteger { 1'000'000 });
+    auto remainder_ns_bigint = modulo(epoch_nanoseconds, Crypto::UnsignedBigInteger { 1'000'000 });
     auto remainder_ns = remainder_ns_bigint.to_double();
 
-    // 3. Let epochMilliseconds be (epochNanoseconds − remainderNs) / 10^6.
-    auto epoch_milliseconds_bigint = epoch_nanoseconds.big_integer().minus(remainder_ns_bigint).divided_by(Crypto::UnsignedBigInteger { 1'000'000 }).quotient;
+    // 3. Let epochMilliseconds be 𝔽((epochNanoseconds − remainderNs) / 10^6).
+    auto epoch_milliseconds_bigint = epoch_nanoseconds.minus(remainder_ns_bigint).divided_by(Crypto::UnsignedBigInteger { 1'000'000 }).quotient;
     auto epoch_milliseconds = epoch_milliseconds_bigint.to_double();
 
-    // 4. Let year be ! YearFromTime(epochMilliseconds).
+    // 4. Let year be ℝ(! YearFromTime(epochMilliseconds)).
     auto year = year_from_time(epoch_milliseconds);
 
-    // 5. Let month be ! MonthFromTime(epochMilliseconds) + 1.
+    // 5. Let month be ℝ(! MonthFromTime(epochMilliseconds)) + 1.
     auto month = static_cast<u8>(month_from_time(epoch_milliseconds) + 1);
 
-    // 6. Let day be ! DateFromTime(epochMilliseconds).
+    // 6. Let day be ℝ(! DateFromTime(epochMilliseconds)).
     auto day = date_from_time(epoch_milliseconds);
 
-    // 7. Let hour be ! HourFromTime(epochMilliseconds).
+    // 7. Let hour be ℝ(! HourFromTime(epochMilliseconds)).
     auto hour = hour_from_time(epoch_milliseconds);
 
-    // 8. Let minute be ! MinFromTime(epochMilliseconds).
+    // 8. Let minute be ℝ(! MinFromTime(epochMilliseconds)).
     auto minute = min_from_time(epoch_milliseconds);
 
-    // 9. Let second be ! SecFromTime(epochMilliseconds).
+    // 9. Let second be ℝ(! SecFromTime(epochMilliseconds)).
     auto second = sec_from_time(epoch_milliseconds);
 
-    // 10. Let millisecond be ! msFromTime(epochMilliseconds).
+    // 10. Let millisecond be ℝ(! msFromTime(epochMilliseconds)).
     auto millisecond = ms_from_time(epoch_milliseconds);
 
     // 11. Let microsecond be floor(remainderNs / 1000) modulo 1000.
@@ -509,7 +512,7 @@ ThrowCompletionOr<PlainDateTime*> builtin_time_zone_get_plain_date_time_for(Glob
     auto offset_nanoseconds = TRY(get_offset_nanoseconds_for(global_object, time_zone, instant));
 
     // 3. Let result be ! GetISOPartsFromEpoch(ℝ(instant.[[Nanoseconds]])).
-    auto result = get_iso_parts_from_epoch(instant.nanoseconds());
+    auto result = get_iso_parts_from_epoch(global_object, instant.nanoseconds().big_integer());
 
     // 4. Set result to ! BalanceISODateTime(result.[[Year]], result.[[Month]], result.[[Day]], result.[[Hour]], result.[[Minute]], result.[[Second]], result.[[Millisecond]], result.[[Microsecond]], result.[[Nanosecond]] + offsetNanoseconds).
     result = balance_iso_date_time(result.year, result.month, result.day, result.hour, result.minute, result.second, result.millisecond, result.microsecond, result.nanosecond + offset_nanoseconds);
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.h b/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.h
index 77432aeb39..6ea07c54d5 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.h
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.h
@@ -40,7 +40,7 @@ String canonicalize_time_zone_name(String const& time_zone);
 String default_time_zone();
 ThrowCompletionOr<String> parse_temporal_time_zone(GlobalObject&, String const&);
 ThrowCompletionOr<TimeZone*> create_temporal_time_zone(GlobalObject&, String const& identifier, FunctionObject const* new_target = nullptr);
-ISODateTime get_iso_parts_from_epoch(BigInt const& epoch_nanoseconds);
+ISODateTime get_iso_parts_from_epoch(GlobalObject&, Crypto::SignedBigInteger const& epoch_nanoseconds);
 MarkedVector<BigInt*> get_iana_time_zone_epoch_value(GlobalObject&, StringView time_zone_identifier, i32 year, u8 month, u8 day, u8 hour, u8 minute, u8 second, u16 millisecond, u16 microsecond, u16 nanosecond);
 i64 get_iana_time_zone_offset_nanoseconds(BigInt const& epoch_nanoseconds, String const& time_zone_identifier);
 BigInt* get_iana_time_zone_next_transition(GlobalObject&, BigInt const& epoch_nanoseconds, StringView time_zone_identifier);