[JSC] Temporal.Instant.prototype.epochMilliseconds should return fl…

…oored value https://bugs.webkit.org/show_bug.cgi?id=278300 Reviewed by Yusuke Suzuki. According to the latest Temporal spec [1], `Temporal.Instant.prototype.epochMilliseconds` should return a floored value. However, the current implementation in JSC returns a truncated value instead of a floored one. This patch changes `Temporal.Instant.prototype.epochMilliseconds` to return a floored value. [1]: https://tc39.es/proposal-temporal/#sec-get-temporal.instant.prototype.epochmilliseconds * JSTests/stress/temporal-instant.js: (instants.forEach): * JSTests/test262/expectations.yaml: * Source/JavaScriptCore/runtime/ISO8601.h: * Source/JavaScriptCore/runtime/TemporalInstantPrototype.cpp: (JSC::JSC_DEFINE_CUSTOM_GETTER): Canonical link: https://commits.webkit.org/282718@main
WebKit · Aug 26, 2024 · 845ee71 · 845ee71
1 parent 08bd5d5
commit 845ee71
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Showing 4 changed files with 10 additions and 5 deletions.
diff --git a/JSTests/stress/temporal-instant.js b/JSTests/stress/temporal-instant.js
@@ -101,7 +101,7 @@ function shouldThrow(func, errorType, message) {
         Temporal.Instant.from('1677-09-21T00:12:43.145224192Z'),
     ];
     instants.forEach((instant) => {
-        shouldBe(instant.epochMilliseconds, -9223372036854);
+        shouldBe(instant.epochMilliseconds, -9223372036855);
         shouldBe(instant.epochNanoseconds, -9223372036854775808n);
         shouldBe(instant.toString(), '1677-09-21T00:12:43.145224192Z');
         shouldBe(instant.toJSON(), '1677-09-21T00:12:43.145224192Z');

diff --git a/JSTests/test262/expectations.yaml b/JSTests/test262/expectations.yaml
@@ -1186,9 +1186,6 @@ test/built-ins/Temporal/Duration/prototype/total/relativeto-propertybag-invalid-
 test/built-ins/Temporal/Duration/prototype/total/total-of-each-unit-relativeto.js:
   default: "TypeError: undefined is not a constructor (evaluating 'new Temporal.ZonedDateTime(63072000_000_000_000n /* = 1972-01-01T00Z */, \"UTC\")')"
   strict mode: "TypeError: undefined is not a constructor (evaluating 'new Temporal.ZonedDateTime(63072000_000_000_000n /* = 1972-01-01T00Z */, \"UTC\")')"
-test/built-ins/Temporal/Instant/prototype/epochMilliseconds/basic.js:
-  default: 'Test262Error: epochMilliseconds pre epoch Expected SameValue(«-217175010876», «-217175010877») to be true'
-  strict mode: 'Test262Error: epochMilliseconds pre epoch Expected SameValue(«-217175010876», «-217175010877») 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'

diff --git a/Source/JavaScriptCore/runtime/ISO8601.h b/Source/JavaScriptCore/runtime/ISO8601.h
@@ -110,6 +110,14 @@ class ExactTime {
     {
         return static_cast<int64_t>(m_epochNanoseconds / ExactTime::nsPerMillisecond);
     }
+    int64_t floorEpochMilliseconds() const
+    {
+        auto div = m_epochNanoseconds / ExactTime::nsPerMillisecond;
+        auto rem = m_epochNanoseconds % ExactTime::nsPerMillisecond;
+        if (rem && m_epochNanoseconds < 0)
+            div -= 1;
+        return static_cast<int64_t>(div);
+    }
     constexpr Int128 epochNanoseconds() const
     {
         return m_epochNanoseconds;

diff --git a/Source/JavaScriptCore/runtime/TemporalInstantPrototype.cpp b/Source/JavaScriptCore/runtime/TemporalInstantPrototype.cpp
@@ -280,7 +280,7 @@ JSC_DEFINE_CUSTOM_GETTER(temporalInstantPrototypeGetterEpochMilliseconds, (JSGlo
     if (!instant)
         return throwVMTypeError(globalObject, scope, "Temporal.Instant.prototype.epochMilliseconds called on value that's not a Instant"_s);
 
-    return JSValue::encode(jsNumber(instant->exactTime().epochMilliseconds()));
+    return JSValue::encode(jsNumber(instant->exactTime().floorEpochMilliseconds()));
 }
 
 JSC_DEFINE_CUSTOM_GETTER(temporalInstantPrototypeGetterEpochNanoseconds, (JSGlobalObject* globalObject, EncodedJSValue thisValue, PropertyName))