fix(jsc): release class-field identifiers with their parser arena

OPENCLAW.md

@@ -145,6 +145,8 @@ baseline. Engine and Bun headers and libraries must be rebuilt together.
 
 ## Unreleased
 
+- Release class-field identifier references when parser arenas are destroyed, preventing native string leaks during class initialization and Worker churn.
+
 - Deliver pending worker heap-limit termination promptly after GC by invalidating optimized code on the mutator, preserving full-GC live accounting and external-buffer exclusions.
 
 - Preserve mimalloc pthread TLS-key ownership during shell exit by draining active setters before deletion; cover both late and in-flight allocations with native regressions. Builds on oven-sh/WebKit#698, thanks @dylan-conway.

Source/JavaScriptCore/parser/Nodes.h

@@ -2401,7 +2401,8 @@ namespace JSC {
         ExpressionNode* m_argument;
     };
 
-    class DefineFieldNode final : public StatementNode {
+    class DefineFieldNode final : public StatementNode, public ParserArenaDeletable {
+        JSC_MAKE_PARSER_ARENA_DELETABLE_ALLOCATED(DefineFieldNode);
     public:
         enum class Type { Name, PrivateName, ComputedName };
         DefineFieldNode(const JSTokenLocation&, const Identifier&, ExpressionNode*, Type);

Tools/TestWebKitAPI/CMakeLists.txt

@@ -221,6 +221,7 @@ if (ENABLE_JAVASCRIPTCORE)
         Tests/JavaScriptCore/DisallowVMEntry.cpp
         Tests/JavaScriptCore/InspectorConsoleMessage.cpp
         Tests/JavaScriptCore/MarkedVector.cpp
+        Tests/JavaScriptCore/ParserArena.cpp
         Tests/JavaScriptCore/PropertySlot.cpp
         Tests/JavaScriptCore/RegularExpression.cpp
         Tests/JavaScriptCore/StrongBlock.cpp

Tools/TestWebKitAPI/Tests/JavaScriptCore/ParserArena.cpp

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2026 Peter Steinberger All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+ * THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+
+#include <JavaScriptCore/IdentifierInlines.h>
+#include <JavaScriptCore/InitializeThreading.h>
+#include <JavaScriptCore/JSLock.h>
+#include <JavaScriptCore/JSCJSValueInlines.h>
+#include <JavaScriptCore/NodeConstructors.h>
+#include <JavaScriptCore/VM.h>
+
+namespace TestWebKitAPI {
+
+TEST(JavaScriptCore_ParserArena, DefineFieldReleasesIdentifier)
+{
+    WTF::initializeMainThread();
+    JSC::initialize();
+    RefPtr<JSC::VM> vm = JSC::VM::create(JSC::HeapType::Small);
+    JSC::JSLockHolder locker(vm.get());
+    auto identifier = JSC::Identifier::fromString(*vm, "parserArenaFieldIdentifier"_s);
+    auto initialRefCount = identifier.impl()->refCount();
+
+    for (auto type : { JSC::DefineFieldNode::Type::Name, JSC::DefineFieldNode::Type::PrivateName, JSC::DefineFieldNode::Type::ComputedName }) {
+        {
+            JSC::ParserArena arena;
+            new (arena) JSC::DefineFieldNode(JSC::JSTokenLocation { }, identifier, nullptr, type);
+            EXPECT_EQ(initialRefCount + 1, identifier.impl()->refCount());
+        }
+        EXPECT_EQ(initialRefCount, identifier.impl()->refCount());
+    }
+    identifier = { };
+    vm = nullptr;
+}
+
+} // namespace TestWebKitAPI