[JSC] Fractional part of an ISO8601 Duration string must not be inter…

…preted as floating-point

https://bugs.webkit.org/show_bug.cgi?id=241940

Reviewed by Yusuke Suzuki.

The last time part of an ISO8601 Duration string is allowed to have 1 to 9 digits beyond the decimal point.
If this fractional part is interpreted using floating-point arithmetic, off-by-one errors can occur.
(https://tc39.es/proposal-temporal/#sec-temporal-parsetemporaldurationstring)

Contrary to the spec, test262 tests had been expecting IEEE-754-aligned results.
Tests were corrected in tc39/test262#3544; this patch corrects our implementation.

* JSTests/test262/expectations.yaml:
Mark 16 test cases as passing.

* Source/JavaScriptCore/runtime/ISO8601.cpp:
(JSC::ISO8601::handleFraction):

Canonical link: https://commits.webkit.org/251809@main

JSTests/test262/expectations.yaml

@@ -831,9 +831,6 @@ test/built-ins/ShadowRealm/prototype/evaluate/throws-typeerror-wrap-throwing.js:
 test/built-ins/ShadowRealm/prototype/importValue/throws-if-exportname-not-string.js:
   default: 'Test262Error: Expected a TypeError but got a Test262Error'
   strict mode: 'Test262Error: Expected a TypeError but got a Test262Error'
-test/built-ins/Temporal/Duration/compare/argument-string-negative-fractional-units.js:
-  default: 'Test262Error: negative fractional hours (first argument) Expected SameValue(«1», «0») to be true'
-  strict mode: 'Test262Error: negative fractional hours (first argument) Expected SameValue(«1», «0») to be true'
 test/built-ins/Temporal/Duration/compare/basic.js:
   default: 'RangeError: Cannot compare a duration of years, months, or weeks without a relativeTo option'
   strict mode: 'RangeError: Cannot compare a duration of years, months, or weeks without a relativeTo option'
@@ -879,12 +876,6 @@ test/built-ins/Temporal/Duration/compare/timezone-wrong-type.js:
 test/built-ins/Temporal/Duration/compare/twenty-five-hour-day.js:
   default: 'TypeError: Right side of assignment cannot be destructured'
   strict mode: 'TypeError: Right side of assignment cannot be destructured'
-test/built-ins/Temporal/Duration/from/argument-string-negative-fractional-units.js:
-  default: 'Test262Error: negative fractional hours nanoseconds result Expected SameValue(«-799», «-800») to be true'
-  strict mode: 'Test262Error: negative fractional hours nanoseconds result Expected SameValue(«-799», «-800») to be true'
-test/built-ins/Temporal/Duration/prototype/add/argument-string-negative-fractional-units.js:
-  default: 'Test262Error: negative fractional hours nanoseconds result Expected SameValue(«-799», «-800») to be true'
-  strict mode: 'Test262Error: negative fractional hours nanoseconds result Expected SameValue(«-799», «-800») to be true'
 test/built-ins/Temporal/Duration/prototype/add/calendar-dateadd-called-with-plaindate-instance.js:
   default: 'RangeError: Cannot add a duration of years, months, or weeks without a relativeTo option'
   strict mode: 'RangeError: Cannot add a duration of years, months, or weeks without a relativeTo option'
@@ -978,9 +969,6 @@ test/built-ins/Temporal/Duration/prototype/round/timezone-wrong-type.js:
 test/built-ins/Temporal/Duration/prototype/round/year-zero.js:
   default: 'Test262Error: reject minus zero as extended year Expected a RangeError but got a Error'
   strict mode: 'Test262Error: reject minus zero as extended year Expected a RangeError but got a Error'
-test/built-ins/Temporal/Duration/prototype/subtract/argument-string-negative-fractional-units.js:
-  default: 'Test262Error: negative fractional hours nanoseconds result Expected SameValue(«799», «800») to be true'
-  strict mode: 'Test262Error: negative fractional hours nanoseconds result Expected SameValue(«799», «800») to be true'
 test/built-ins/Temporal/Duration/prototype/subtract/calendar-dateadd-called-with-plaindate-instance.js:
   default: 'RangeError: Cannot subtract a duration of years, months, or weeks without a relativeTo option'
   strict mode: 'RangeError: Cannot subtract a duration of years, months, or weeks without a relativeTo option'
@@ -1065,15 +1053,9 @@ test/built-ins/Temporal/Duration/prototype/total/timezone-wrong-type.js:
 test/built-ins/Temporal/Duration/prototype/total/unit-plurals-accepted-string.js:
   default: 'TypeError: Right hand side of instanceof is not an object'
   strict mode: 'TypeError: Right hand side of instanceof is not an object'
-test/built-ins/Temporal/Instant/prototype/add/argument-string-negative-fractional-units.js:
-  default: 'Test262Error: negative fractional hours Expected SameValue(«999911555595557201», «999911555595557200») to be true'
-  strict mode: 'Test262Error: negative fractional hours Expected SameValue(«999911555595557201», «999911555595557200») to be true'
 test/built-ins/Temporal/Instant/prototype/since/largestunit.js:
   default: 'Test262Error: does not include higher units than necessary (largest unit unspecified) nanoseconds result Expected SameValue(«40», «101») to be true'
   strict mode: 'Test262Error: does not include higher units than necessary (largest unit unspecified) nanoseconds result Expected SameValue(«40», «101») to be true'
-test/built-ins/Temporal/Instant/prototype/subtract/argument-string-negative-fractional-units.js:
-  default: 'Test262Error: negative fractional hours Expected SameValue(«1000088444404442799», «1000088444404442800») to be true'
-  strict mode: 'Test262Error: negative fractional hours Expected SameValue(«1000088444404442799», «1000088444404442800») to be true'
 test/built-ins/Temporal/Instant/prototype/toJSON/timezone-getoffsetnanosecondsfor-not-callable.js:
   default: 'Test262Error: Uncallable undefined getOffsetNanosecondsFor should throw TypeError Expected a TypeError to be thrown but no exception was thrown at all'
   strict mode: 'Test262Error: Uncallable undefined getOffsetNanosecondsFor should throw TypeError Expected a TypeError to be thrown but no exception was thrown at all'
@@ -1101,18 +1083,12 @@ test/built-ins/Temporal/PlainTime/from/argument-string-with-calendar.js:
 test/built-ins/Temporal/PlainTime/from/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js:
   default: "TypeError: undefined is not a constructor (evaluating 'new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone)')"
   strict mode: "TypeError: undefined is not a constructor (evaluating 'new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone)')"
-test/built-ins/Temporal/PlainTime/prototype/add/argument-string-negative-fractional-units.js:
-  default: 'Test262Error: negative fractional hours nanosecond result Expected SameValue(«201», «200») to be true'
-  strict mode: 'Test262Error: negative fractional hours nanosecond result Expected SameValue(«201», «200») to be true'
 test/built-ins/Temporal/PlainTime/prototype/equals/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js:
   default: "TypeError: undefined is not a constructor (evaluating 'new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone)')"
   strict mode: "TypeError: undefined is not a constructor (evaluating 'new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone)')"
 test/built-ins/Temporal/PlainTime/prototype/since/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js:
   default: "TypeError: undefined is not a constructor (evaluating 'new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone)')"
   strict mode: "TypeError: undefined is not a constructor (evaluating 'new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone)')"
-test/built-ins/Temporal/PlainTime/prototype/subtract/argument-string-negative-fractional-units.js:
-  default: 'Test262Error: negative fractional hours nanosecond result Expected SameValue(«799», «800») to be true'
-  strict mode: 'Test262Error: negative fractional hours nanosecond result Expected SameValue(«799», «800») to be true'
 test/built-ins/Temporal/PlainTime/prototype/until/argument-zoneddatetime-timezone-getoffsetnanosecondsfor-not-callable.js:
   default: "TypeError: undefined is not a constructor (evaluating 'new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone)')"
   strict mode: "TypeError: undefined is not a constructor (evaluating 'new Temporal.ZonedDateTime(1_000_000_000_987_654_321n, timeZone)')"

Source/JavaScriptCore/runtime/ISO8601.cpp

@@ -70,50 +70,38 @@ static int32_t parseDecimalInt32(const CharType* characters, unsigned length)
 // https://tc39.es/proposal-temporal/#sec-temporal-durationhandlefractions
 static void handleFraction(Duration& duration, int factor, StringView fractionString, TemporalUnit fractionType)
 {
-    ASSERT(fractionString.length() && fractionString.length() <= 9 && fractionString.isAllASCII());
+    auto fractionLength = fractionString.length();
+    ASSERT(fractionLength && fractionLength <= 9 && fractionString.isAllASCII());
     ASSERT(fractionType == TemporalUnit::Hour || fractionType == TemporalUnit::Minute || fractionType == TemporalUnit::Second);
 
-    if (fractionType == TemporalUnit::Second) {
-        Vector<LChar, 9> padded(9, '0');
-        for (unsigned i = 0; i < fractionString.length(); i++)
-            padded[i] = fractionString[i];
-        duration.setMilliseconds(factor * parseDecimalInt32(padded.data(), 3));
-        duration.setMicroseconds(factor * parseDecimalInt32(padded.data() + 3, 3));
-        duration.setNanoseconds(factor * parseDecimalInt32(padded.data() + 6, 3));
-        return;
-    }
+    Vector<LChar, 9> padded(9, '0');
+    for (unsigned i = 0; i < fractionLength; i++)
+        padded[i] = fractionString[i];
 
-    double fraction = factor * parseInt(fractionString, 10) / std::pow(10, fractionString.length());
+    int64_t fraction = static_cast<int64_t>(factor) * parseDecimalInt32(padded.data(), 9);
     if (!fraction)
         return;
 
+    static constexpr int64_t divisor = 1'000'000'000LL;
     if (fractionType == TemporalUnit::Hour) {
         fraction *= 60;
-        duration.setMinutes(std::trunc(fraction));
-        fraction = std::fmod(fraction, 1);
+        duration.setMinutes(fraction / divisor);
+        fraction %= divisor;
         if (!fraction)
             return;
     }
 
-    fraction *= 60;
-    duration.setSeconds(std::trunc(fraction));
-    fraction = std::fmod(fraction, 1);
-    if (!fraction)
-        return;
-
-    fraction *= 1000;
-    duration.setMilliseconds(std::trunc(fraction));
-    fraction = std::fmod(fraction, 1);
-    if (!fraction)
-        return;
-
-    fraction *= 1000;
-    duration.setMicroseconds(std::trunc(fraction));
-    fraction = std::fmod(fraction, 1);
-    if (!fraction)
-        return;
+    if (fractionType != TemporalUnit::Second) {
+        fraction *= 60;
+        duration.setSeconds(fraction / divisor);
+        fraction %= divisor;
+        if (!fraction)
+            return;
+    }
 
-    duration.setNanoseconds(std::trunc(fraction * 1000));
+    duration.setMilliseconds(fraction / nsPerMillisecond);
+    duration.setMicroseconds(fraction % nsPerMillisecond / nsPerMicrosecond);
+    duration.setNanoseconds(fraction % nsPerMicrosecond);
 }
 
 // ParseTemporalDurationString ( isoString )