Defer termination at the reifyStaticProperty call sites and propagate builder exceptions

Source/JavaScriptCore/runtime/JSObject.cpp

@@ -2948,6 +2948,10 @@ void JSObject::reifyAllStaticProperties(JSGlobalObject* globalObject)
     if (!structure()->isDictionary())
         convertToDictionary(vm);
 
+    // A PropertyCallback builder can enter JS; defer termination (like
+    // LazyProperty::callFunc) so it can't return with one pending.
+    auto scope = DECLARE_THROW_SCOPE(vm);
+    DeferTerminationForAWhile deferScope(vm);
     for (const ClassInfo* info = classInfo(); info; info = info->parentClass) {
         const HashTable* hashTable = info->staticPropHashTable;
         if (!hashTable)
@@ -2957,8 +2961,11 @@ void JSObject::reifyAllStaticProperties(JSGlobalObject* globalObject)
             unsigned attributes;
             auto key = Identifier::fromString(vm, value.m_key);
             PropertyOffset offset = getDirectOffset(vm, key, attributes);
-            if (!isValidOffset(offset))
+            if (!isValidOffset(offset)) {
                 reifyStaticProperty(vm, hashTable->classForThis, key, value, *this);
+                // Leave the rest lazy on throw; the caller propagates.
+                RETURN_IF_EXCEPTION(scope, void());
+            }
         }
     }
 

Source/JavaScriptCore/runtime/Lookup.cpp

@@ -20,6 +20,7 @@
 #include "config.h"
 #include "Lookup.h"
 
+#include "DeferTermination.h"
 #include "GetterSetter.h"
 #include "JSCInlines.h"
 #include <wtf/text/MakeString.h>
@@ -58,7 +59,17 @@ bool setUpStaticFunctionSlot(VM& vm, const ClassInfo* classInfo, const HashTable
         if (thisObject->staticPropertiesReified())
             return false;
 
-        reifyStaticProperty(vm, classInfo, propertyName, *entry, *thisObject);
+        auto scope = DECLARE_THROW_SCOPE(vm);
+        {
+            // A PropertyCallback builder can enter JS; defer termination (like
+            // LazyProperty::callFunc) so it can't return with one pending.
+            DeferTerminationForAWhile deferScope(vm);
+            reifyStaticProperty(vm, classInfo, propertyName, *entry, *thisObject);
+        }
+        // The builder may still throw a non-termination exception; report the
+        // slot as not found so JSValue::get / getOwnPropertyDescriptor's
+        // EXCEPTION_ASSERT(!scope.exception() || !result) holds.
+        RETURN_IF_EXCEPTION(scope, false);
 
         offset = thisObject->getDirectOffset(vm, propertyName, attributes);
         if (!isValidOffset(offset)) {

Source/JavaScriptCore/runtime/Lookup.h

@@ -538,6 +538,11 @@ inline void reifyStaticProperty(VM& vm, const ClassInfo* classInfo, const Proper
 
     if (value.attributes() & PropertyAttribute::PropertyCallback) {
         JSValue result = value.lazyPropertyCallback()(vm, &thisObj);
+        // A callback that enters JS may return empty with an exception pending;
+        // the two callers (setUpStaticFunctionSlot / reifyAllStaticProperties)
+        // check and propagate, so don't put an empty value in the slot here.
+        if (!result) [[unlikely]]
+            return;
         thisObj.putDirect(vm, propertyName, result, attributesForStructure(value.attributes()));
         return;
     }