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JSC: tolerate pending TerminationException in property-lookup assertions #286

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JSC: tolerate pending TerminationException in property-lookup assertions #286

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JSC: tolerate pending TerminationException in property-lookup assertions
Jarred-Sumner Jul 13, 2026
98e25e0
Merge branch 'main' into jsc/tolerate-termination-in-property-asserts
Jarred-Sumner Jul 17, 2026
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14 changes: 11 additions & 3 deletions Source/JavaScriptCore/runtime/JSCJSValuePropertyInlines.h
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Original file line number Diff line number Diff line change
Expand Up @@ -46,9 +46,14 @@ ALWAYS_INLINE JSValue JSValue::get(JSGlobalObject* globalObject, PropertyName pr

ALWAYS_INLINE JSValue JSValue::get(JSGlobalObject* globalObject, PropertyName propertyName, PropertySlot& slot) const
{
auto scope = DECLARE_THROW_SCOPE(getVM(globalObject));
VM& vm = getVM(globalObject);
auto scope = DECLARE_THROW_SCOPE(vm);
bool hasSlot = getPropertySlot(globalObject, propertyName, slot);
EXCEPTION_ASSERT(!scope.exception() || !hasSlot);
// A DeferTermination scope unwinding inside the slot lookup can throw the
// TerminationException after the property was found; tolerate it like
// JSObject::get does and let the caller's exception check unwind.
EXCEPTION_ASSERT(!scope.exception() || vm.hasPendingTerminationException() || !hasSlot);
RETURN_IF_EXCEPTION(scope, jsUndefined());
if (!hasSlot)
return jsUndefined();
RELEASE_AND_RETURN(scope, slot.getValue(globalObject, propertyName));
Expand Down Expand Up @@ -136,7 +141,10 @@ ALWAYS_INLINE JSValue JSValue::get(JSGlobalObject* globalObject, unsigned proper
object = asObject(asCell());

bool hasSlot = object->getPropertySlot(globalObject, propertyName, slot);
EXCEPTION_ASSERT(!scope.exception() || !hasSlot);
// See JSValue::get(JSGlobalObject*, PropertyName, PropertySlot&) above:
// termination can be thrown after a successful lookup.
EXCEPTION_ASSERT(!scope.exception() || getVM(globalObject).hasPendingTerminationException() || !hasSlot);
RETURN_IF_EXCEPTION(scope, jsUndefined());
if (!hasSlot)
return jsUndefined();
RELEASE_AND_RETURN(scope, slot.getValue(globalObject, propertyName));
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5 changes: 4 additions & 1 deletion Source/JavaScriptCore/runtime/JSModuleLoader.cpp
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Expand Up @@ -1023,7 +1023,10 @@ void JSModuleLoader::continueDynamicImport(JSGlobalObject* globalObject, ModuleL
// 1.a. Perform ! Call(promiseCapability.[[Reject]], undefined, « moduleCompletion.[[Value]] »).
promise->reject(vm, (*exception)->value());
// 1.b. Return UNUSED.
scope.assertNoException();
// The abrupt completion may be a resolution failure caused by the
// TerminationException, which rejectWithCaughtException cannot clear;
// it stays pending in the VM and the caller's exception check unwinds.
scope.assertNoExceptionExceptTermination();
return;
}
// 2. Let module be moduleCompletion.[[Value]].
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6 changes: 5 additions & 1 deletion Source/JavaScriptCore/runtime/JSObject.cpp
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Expand Up @@ -3933,7 +3933,11 @@ bool JSObject::getOwnPropertyDescriptor(JSGlobalObject* globalObject, PropertyNa
PropertySlot slot(this, PropertySlot::InternalMethodType::GetOwnProperty);

bool result = methodTable()->getOwnPropertySlot(this, globalObject, propertyName, slot);
EXCEPTION_ASSERT_UNUSED(scope, !scope.exception() || !result);
// A DeferTermination scope unwinding inside the slot lookup can throw the
// TerminationException after the property was found; tolerate it like
// JSObject::get does and let the caller's exception check unwind.
EXCEPTION_ASSERT(!scope.exception() || vm.hasPendingTerminationException() || !result);
RETURN_IF_EXCEPTION(scope, false);
if (!result)
return false;

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