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LibJS: Fix incorrect use of "modulo" in get_iso_parts_from_epoch()

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This would return incorrect results for negative inputs. It still does
to some extent, remainder() in step 2 might need to be replaced with
modulo (I opened an issue in tc39/proposal-temporal about that).
This commit is contained in:
Linus Groh 2021-11-17 22:31:28 +00:00
parent ec1e1f4f12
commit eaa3329573
1 changed files with 5 additions and 5 deletions
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10
Userland/Libraries/LibJS/Runtime/Temporal/TimeZone.cpp
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@ -118,11 +118,11 @@ ISODateTime get_iso_parts_from_epoch(BigInt const& epoch_nanoseconds)
// 2. Let remainderNs be remainder(epochNanoseconds, 10^6).
auto remainder_ns_bigint = epoch_nanoseconds.big_integer().divided_by(Crypto::UnsignedBigInteger { 1'000'000 }).remainder;
auto remainder_ns = remainder_ns_bigint.to_base(10).to_int<i64>().value();
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;
auto epoch_milliseconds = (double)epoch_milliseconds_bigint.to_base(10).to_int<i64>().value();
auto epoch_milliseconds = epoch_milliseconds_bigint.to_double();
// 4. Let year be ! YearFromTime(epochMilliseconds).
auto year = year_from_time(epoch_milliseconds);
@ -146,13 +146,13 @@ ISODateTime get_iso_parts_from_epoch(BigInt const& epoch_nanoseconds)
auto millisecond = ms_from_time(epoch_milliseconds);
// 11. Let microsecond be floor(remainderNs / 1000) modulo 1000.
auto microsecond = static_cast<u16>((remainder_ns / 1000) % 1000);
auto microsecond = modulo(floor(remainder_ns / 1000), 1000.0);
// 12. Let nanosecond be remainderNs modulo 1000.
auto nanosecond = static_cast<u16>(remainder_ns % 1000);
auto nanosecond = modulo(remainder_ns, 1000.0);
// 13. Return the Record { [[Year]]: year, [[Month]]: month, [[Day]]: day, [[Hour]]: hour, [[Minute]]: minute, [[Second]]: second, [[Millisecond]]: millisecond, [[Microsecond]]: microsecond, [[Nanosecond]]: nanosecond }.
return { .year = year, .month = month, .day = day, .hour = hour, .minute = minute, .second = second, .millisecond = millisecond, .microsecond = microsecond, .nanosecond = nanosecond };
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) };
}
// 11.6.4 GetIANATimeZoneEpochValue ( timeZoneIdentifier, year, month, day, hour, minute, second, millisecond, microsecond, nanosecond ), https://tc39.es/proposal-temporal/#sec-temporal-getianatimezoneepochvalue