src: improve handling of internal field counting

Change suggested by bnoordhuis.

Improve handing of internal field counting by using enums.
Helps protect against future possible breakage if field
indexes are ever changed or added to.

Signed-off-by: James M Snell <jasnell@gmail.com>

PR-URL: https://github.com/nodejs/node/pull/31960
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

src/async_wrap.cc

@@ -176,6 +176,10 @@ void AsyncWrap::EmitAfter(Environment* env, double async_id) {
 
 class PromiseWrap : public AsyncWrap {
  public:
+  enum InternalFields {
+    kIsChainedPromiseField = AsyncWrap::kInternalFieldCount,
+    kInternalFieldCount
+  };
   PromiseWrap(Environment* env, Local<Object> object, bool silent)
       : AsyncWrap(env, object, PROVIDER_PROMISE, kInvalidAsyncId, silent) {
     MakeWeak();
@@ -185,9 +189,6 @@ class PromiseWrap : public AsyncWrap {
   SET_MEMORY_INFO_NAME(PromiseWrap)
   SET_SELF_SIZE(PromiseWrap)
 
-  static constexpr int kIsChainedPromiseField = 1;
-  static constexpr int kInternalFieldCount = 2;
-
   static PromiseWrap* New(Environment* env,
                           Local<Promise> promise,
                           PromiseWrap* parent_wrap,
@@ -214,15 +215,16 @@ PromiseWrap* PromiseWrap::New(Environment* env,
 void PromiseWrap::getIsChainedPromise(Local<String> property,
                                       const PropertyCallbackInfo<Value>& info) {
   info.GetReturnValue().Set(
-    info.Holder()->GetInternalField(kIsChainedPromiseField));
+      info.Holder()->GetInternalField(PromiseWrap::kIsChainedPromiseField));
 }
 
 static PromiseWrap* extractPromiseWrap(Local<Promise> promise) {
-  Local<Value> resource_object_value = promise->GetInternalField(0);
+  // This check is imperfect. If the internal field is set, it should
-  if (resource_object_value->IsObject()) {
+  // be an object. If it's not, we just ignore it. Ideally v8 would
-    return Unwrap<PromiseWrap>(resource_object_value.As<Object>());
+  // have had GetInternalField returning a MaybeLocal but this works
-  }
+  // for now.
-  return nullptr;
+  Local<Value> obj = promise->GetInternalField(0);
+  return obj->IsObject() ? Unwrap<PromiseWrap>(obj.As<Object>()) : nullptr;
 }
 
 static void PromiseHook(PromiseHookType type, Local<Promise> promise,
@@ -560,7 +562,7 @@ void AsyncWrap::Initialize(Local<Object> target,
     function_template->SetClassName(class_name);
     function_template->Inherit(AsyncWrap::GetConstructorTemplate(env));
     auto instance_template = function_template->InstanceTemplate();
-    instance_template->SetInternalFieldCount(1);
+    instance_template->SetInternalFieldCount(AsyncWrap::kInternalFieldCount);
     auto function =
         function_template->GetFunction(env->context()).ToLocalChecked();
     target->Set(env->context(), class_name, function).Check();

src/base_object-inl.h

@@ -43,7 +43,9 @@ BaseObject::BaseObject(Environment* env, v8::Local<v8::Object> object)
     : persistent_handle_(env->isolate(), object), env_(env) {
   CHECK_EQ(false, object.IsEmpty());
   CHECK_GT(object->InternalFieldCount(), 0);
-  object->SetAlignedPointerInInternalField(0, static_cast<void*>(this));
+  object->SetAlignedPointerInInternalField(
+      BaseObject::kSlot,
+      static_cast<void*>(this));
   env->AddCleanupHook(DeleteMe, static_cast<void*>(this));
   env->modify_base_object_count(1);
 }
@@ -67,7 +69,7 @@ BaseObject::~BaseObject() {
 
   {
     v8::HandleScope handle_scope(env()->isolate());
-    object()->SetAlignedPointerInInternalField(0, nullptr);
+    object()->SetAlignedPointerInInternalField(BaseObject::kSlot, nullptr);
   }
 }
 
@@ -100,7 +102,8 @@ Environment* BaseObject::env() const {
 
 BaseObject* BaseObject::FromJSObject(v8::Local<v8::Object> obj) {
   CHECK_GT(obj->InternalFieldCount(), 0);
-  return static_cast<BaseObject*>(obj->GetAlignedPointerFromInternalField(0));
+  return static_cast<BaseObject*>(
+      obj->GetAlignedPointerFromInternalField(BaseObject::kSlot));
 }
 
 
@@ -148,11 +151,12 @@ BaseObject::MakeLazilyInitializedJSTemplate(Environment* env) {
   auto constructor = [](const v8::FunctionCallbackInfo<v8::Value>& args) {
     DCHECK(args.IsConstructCall());
     DCHECK_GT(args.This()->InternalFieldCount(), 0);
-    args.This()->SetAlignedPointerInInternalField(0, nullptr);
+    args.This()->SetAlignedPointerInInternalField(BaseObject::kSlot, nullptr);
   };
 
   v8::Local<v8::FunctionTemplate> t = env->NewFunctionTemplate(constructor);
-  t->InstanceTemplate()->SetInternalFieldCount(1);
+  t->InstanceTemplate()->SetInternalFieldCount(
+      BaseObject::kInternalFieldCount);
   return t;
 }
 

src/base_object.h

@@ -36,6 +36,8 @@ class BaseObjectPtrImpl;
 
 class BaseObject : public MemoryRetainer {
  public:
+  enum InternalFields { kSlot, kInternalFieldCount };
+
   // Associates this object with `object`. It uses the 0th internal field for
   // that, and in particular aborts if there is no such field.
   inline BaseObject(Environment* env, v8::Local<v8::Object> object);

src/cares_wrap.cc

@@ -2223,7 +2223,8 @@ void Initialize(Local<Object> target,
 
   Local<FunctionTemplate> channel_wrap =
       env->NewFunctionTemplate(ChannelWrap::New);
-  channel_wrap->InstanceTemplate()->SetInternalFieldCount(1);
+  channel_wrap->InstanceTemplate()->SetInternalFieldCount(
+      ChannelWrap::kInternalFieldCount);
   channel_wrap->Inherit(AsyncWrap::GetConstructorTemplate(env));
 
   env->SetProtoMethod(channel_wrap, "queryAny", Query<QueryAnyWrap>);

src/fs_event_wrap.cc

@@ -97,7 +97,8 @@ void FSEventWrap::Initialize(Local<Object> target,
 
   auto fsevent_string = FIXED_ONE_BYTE_STRING(env->isolate(), "FSEvent");
   Local<FunctionTemplate> t = env->NewFunctionTemplate(New);
-  t->InstanceTemplate()->SetInternalFieldCount(1);
+  t->InstanceTemplate()->SetInternalFieldCount(
+      FSEventWrap::kInternalFieldCount);
   t->SetClassName(fsevent_string);
 
   t->Inherit(AsyncWrap::GetConstructorTemplate(env));

src/heap_utils.cc

@@ -341,7 +341,7 @@ BaseObjectPtr<AsyncWrap> CreateHeapSnapshotStream(
     Local<FunctionTemplate> os = FunctionTemplate::New(env->isolate());
     os->Inherit(AsyncWrap::GetConstructorTemplate(env));
     Local<ObjectTemplate> ost = os->InstanceTemplate();
-    ost->SetInternalFieldCount(StreamBase::kStreamBaseFieldCount);
+    ost->SetInternalFieldCount(StreamBase::kInternalFieldCount);
     os->SetClassName(
         FIXED_ONE_BYTE_STRING(env->isolate(), "HeapSnapshotStream"));
     StreamBase::AddMethods(env, os);

src/inspector_js_api.cc

@@ -105,7 +105,8 @@ class JSBindingsConnection : public AsyncWrap {
     Local<String> class_name = ConnectionType::GetClassName(env);
     Local<FunctionTemplate> tmpl =
         env->NewFunctionTemplate(JSBindingsConnection::New);
-    tmpl->InstanceTemplate()->SetInternalFieldCount(1);
+    tmpl->InstanceTemplate()->SetInternalFieldCount(
+        JSBindingsConnection::kInternalFieldCount);
     tmpl->SetClassName(class_name);
     tmpl->Inherit(AsyncWrap::GetConstructorTemplate(env));
     env->SetProtoMethod(tmpl, "dispatch", JSBindingsConnection::Dispatch);

src/js_stream.cc

@@ -204,7 +204,7 @@ void JSStream::Initialize(Local<Object> target,
       FIXED_ONE_BYTE_STRING(env->isolate(), "JSStream");
   t->SetClassName(jsStreamString);
   t->InstanceTemplate()
-    ->SetInternalFieldCount(StreamBase::kStreamBaseFieldCount);
+    ->SetInternalFieldCount(StreamBase::kInternalFieldCount);
   t->Inherit(AsyncWrap::GetConstructorTemplate(env));
 
   env->SetProtoMethod(t, "finishWrite", Finish<WriteWrap>);

src/module_wrap.cc

@@ -1636,7 +1636,8 @@ void ModuleWrap::Initialize(Local<Object> target,
 
   Local<FunctionTemplate> tpl = env->NewFunctionTemplate(New);
   tpl->SetClassName(FIXED_ONE_BYTE_STRING(isolate, "ModuleWrap"));
-  tpl->InstanceTemplate()->SetInternalFieldCount(1);
+  tpl->InstanceTemplate()->SetInternalFieldCount(
+      ModuleWrap::kInternalFieldCount);
 
   env->SetProtoMethod(tpl, "link", Link);
   env->SetProtoMethod(tpl, "instantiate", Instantiate);

src/node_contextify.cc

@@ -145,7 +145,7 @@ MaybeLocal<Object> ContextifyContext::CreateDataWrapper(Environment* env) {
     return MaybeLocal<Object>();
   }
 
-  wrapper->SetAlignedPointerInInternalField(0, this);
+  wrapper->SetAlignedPointerInInternalField(ContextifyContext::kSlot, this);
   return wrapper;
 }
 
@@ -232,7 +232,8 @@ MaybeLocal<Context> ContextifyContext::CreateV8Context(
 void ContextifyContext::Init(Environment* env, Local<Object> target) {
   Local<FunctionTemplate> function_template =
       FunctionTemplate::New(env->isolate());
-  function_template->InstanceTemplate()->SetInternalFieldCount(1);
+  function_template->InstanceTemplate()->SetInternalFieldCount(
+      ContextifyContext::kInternalFieldCount);
   env->set_script_data_constructor_function(
       function_template->GetFunction(env->context()).ToLocalChecked());
 
@@ -331,7 +332,8 @@ template <typename T>
 ContextifyContext* ContextifyContext::Get(const PropertyCallbackInfo<T>& args) {
   Local<Value> data = args.Data();
   return static_cast<ContextifyContext*>(
-      data.As<Object>()->GetAlignedPointerFromInternalField(0));
+      data.As<Object>()->GetAlignedPointerFromInternalField(
+          ContextifyContext::kSlot));
 }
 
 // static
@@ -628,7 +630,8 @@ void ContextifyScript::Init(Environment* env, Local<Object> target) {
       FIXED_ONE_BYTE_STRING(env->isolate(), "ContextifyScript");
 
   Local<FunctionTemplate> script_tmpl = env->NewFunctionTemplate(New);
-  script_tmpl->InstanceTemplate()->SetInternalFieldCount(1);
+  script_tmpl->InstanceTemplate()->SetInternalFieldCount(
+      ContextifyScript::kInternalFieldCount);
   script_tmpl->SetClassName(class_name);
   env->SetProtoMethod(script_tmpl, "createCachedData", CreateCachedData);
   env->SetProtoMethod(script_tmpl, "runInContext", RunInContext);
@@ -1251,7 +1254,8 @@ void Initialize(Local<Object> target,
   {
     Local<FunctionTemplate> tpl = FunctionTemplate::New(env->isolate());
     tpl->SetClassName(FIXED_ONE_BYTE_STRING(env->isolate(), "CompiledFnEntry"));
-    tpl->InstanceTemplate()->SetInternalFieldCount(1);
+    tpl->InstanceTemplate()->SetInternalFieldCount(
+        CompiledFnEntry::kInternalFieldCount);
 
     env->set_compiled_fn_entry_template(tpl->InstanceTemplate());
   }

src/node_contextify.h

@@ -19,6 +19,7 @@ struct ContextOptions {
 
 class ContextifyContext {
  public:
+  enum InternalFields { kSlot, kInternalFieldCount };
   ContextifyContext(Environment* env,
                     v8::Local<v8::Object> sandbox_obj,
                     const ContextOptions& options);

src/node_crypto.cc

@@ -464,7 +464,8 @@ static T* MallocOpenSSL(size_t count) {
 
 void SecureContext::Initialize(Environment* env, Local<Object> target) {
   Local<FunctionTemplate> t = env->NewFunctionTemplate(New);
-  t->InstanceTemplate()->SetInternalFieldCount(1);
+  t->InstanceTemplate()->SetInternalFieldCount(
+      SecureContext::kInternalFieldCount);
   Local<String> secureContextString =
       FIXED_ONE_BYTE_STRING(env->isolate(), "SecureContext");
   t->SetClassName(secureContextString);
@@ -3803,7 +3804,8 @@ EVP_PKEY* ManagedEVPPKey::get() const {
 
 Local<Function> KeyObject::Initialize(Environment* env, Local<Object> target) {
   Local<FunctionTemplate> t = env->NewFunctionTemplate(New);
-  t->InstanceTemplate()->SetInternalFieldCount(1);
+  t->InstanceTemplate()->SetInternalFieldCount(
+      KeyObject::kInternalFieldCount);
 
   env->SetProtoMethod(t, "init", Init);
   env->SetProtoMethodNoSideEffect(t, "getSymmetricKeySize",
@@ -4036,7 +4038,8 @@ CipherBase::CipherBase(Environment* env,
 void CipherBase::Initialize(Environment* env, Local<Object> target) {
   Local<FunctionTemplate> t = env->NewFunctionTemplate(New);
 
-  t->InstanceTemplate()->SetInternalFieldCount(1);
+  t->InstanceTemplate()->SetInternalFieldCount(
+      CipherBase::kInternalFieldCount);
 
   env->SetProtoMethod(t, "init", Init);
   env->SetProtoMethod(t, "initiv", InitIv);
@@ -4663,7 +4666,8 @@ Hmac::Hmac(Environment* env, v8::Local<v8::Object> wrap)
 void Hmac::Initialize(Environment* env, Local<Object> target) {
   Local<FunctionTemplate> t = env->NewFunctionTemplate(New);
 
-  t->InstanceTemplate()->SetInternalFieldCount(1);
+  t->InstanceTemplate()->SetInternalFieldCount(
+      Hmac::kInternalFieldCount);
 
   env->SetProtoMethod(t, "init", HmacInit);
   env->SetProtoMethod(t, "update", HmacUpdate);
@@ -4789,7 +4793,8 @@ Hash::Hash(Environment* env, v8::Local<v8::Object> wrap)
 void Hash::Initialize(Environment* env, Local<Object> target) {
   Local<FunctionTemplate> t = env->NewFunctionTemplate(New);
 
-  t->InstanceTemplate()->SetInternalFieldCount(1);
+  t->InstanceTemplate()->SetInternalFieldCount(
+      Hash::kInternalFieldCount);
 
   env->SetProtoMethod(t, "update", HashUpdate);
   env->SetProtoMethod(t, "digest", HashDigest);
@@ -5061,7 +5066,8 @@ Sign::Sign(Environment* env, v8::Local<v8::Object> wrap) : SignBase(env, wrap) {
 void Sign::Initialize(Environment* env, Local<Object> target) {
   Local<FunctionTemplate> t = env->NewFunctionTemplate(New);
 
-  t->InstanceTemplate()->SetInternalFieldCount(1);
+  t->InstanceTemplate()->SetInternalFieldCount(
+      SignBase::kInternalFieldCount);
 
   env->SetProtoMethod(t, "init", SignInit);
   env->SetProtoMethod(t, "update", SignUpdate);
@@ -5385,7 +5391,8 @@ Verify::Verify(Environment* env, v8::Local<v8::Object> wrap) :
 void Verify::Initialize(Environment* env, Local<Object> target) {
   Local<FunctionTemplate> t = env->NewFunctionTemplate(New);
 
-  t->InstanceTemplate()->SetInternalFieldCount(1);
+  t->InstanceTemplate()->SetInternalFieldCount(
+      SignBase::kInternalFieldCount);
 
   env->SetProtoMethod(t, "init", VerifyInit);
   env->SetProtoMethod(t, "update", VerifyUpdate);
@@ -5697,7 +5704,8 @@ void DiffieHellman::Initialize(Environment* env, Local<Object> target) {
     const PropertyAttribute attributes =
         static_cast<PropertyAttribute>(ReadOnly | DontDelete);
 
-    t->InstanceTemplate()->SetInternalFieldCount(1);
+    t->InstanceTemplate()->SetInternalFieldCount(
+        DiffieHellman::kInternalFieldCount);
 
     env->SetProtoMethod(t, "generateKeys", GenerateKeys);
     env->SetProtoMethod(t, "computeSecret", ComputeSecret);
@@ -6036,7 +6044,7 @@ void ECDH::Initialize(Environment* env, Local<Object> target) {
 
   Local<FunctionTemplate> t = env->NewFunctionTemplate(New);
 
-  t->InstanceTemplate()->SetInternalFieldCount(1);
+  t->InstanceTemplate()->SetInternalFieldCount(ECDH::kInternalFieldCount);
 
   env->SetProtoMethod(t, "generateKeys", GenerateKeys);
   env->SetProtoMethod(t, "computeSecret", ComputeSecret);

src/node_dir.cc

@@ -358,7 +358,7 @@ void Initialize(Local<Object> target,
   env->SetProtoMethod(dir, "read", DirHandle::Read);
   env->SetProtoMethod(dir, "close", DirHandle::Close);
   Local<ObjectTemplate> dirt = dir->InstanceTemplate();
-  dirt->SetInternalFieldCount(DirHandle::kDirHandleFieldCount);
+  dirt->SetInternalFieldCount(DirHandle::kInternalFieldCount);
   Local<String> handleString =
        FIXED_ONE_BYTE_STRING(isolate, "DirHandle");
   dir->SetClassName(handleString);

src/node_dir.h

@@ -12,8 +12,6 @@ namespace fs_dir {
 // Needed to propagate `uv_dir_t`.
 class DirHandle : public AsyncWrap {
  public:
-  static constexpr int kDirHandleFieldCount = 1;
-
   static DirHandle* New(Environment* env, uv_dir_t* dir);
   ~DirHandle() override;
 

src/node_file.cc

@@ -2290,7 +2290,8 @@ void Initialize(Local<Object> target,
 
   // Create FunctionTemplate for FSReqCallback
   Local<FunctionTemplate> fst = env->NewFunctionTemplate(NewFSReqCallback);
-  fst->InstanceTemplate()->SetInternalFieldCount(1);
+  fst->InstanceTemplate()->SetInternalFieldCount(
+      FSReqBase::kInternalFieldCount);
   fst->Inherit(AsyncWrap::GetConstructorTemplate(env));
   Local<String> wrapString =
       FIXED_ONE_BYTE_STRING(isolate, "FSReqCallback");
@@ -2303,7 +2304,8 @@ void Initialize(Local<Object> target,
   // Create FunctionTemplate for FileHandleReadWrap. There’s no need
   // to do anything in the constructor, so we only store the instance template.
   Local<FunctionTemplate> fh_rw = FunctionTemplate::New(isolate);
-  fh_rw->InstanceTemplate()->SetInternalFieldCount(1);
+  fh_rw->InstanceTemplate()->SetInternalFieldCount(
+      FSReqBase::kInternalFieldCount);
   fh_rw->Inherit(AsyncWrap::GetConstructorTemplate(env));
   Local<String> fhWrapString =
       FIXED_ONE_BYTE_STRING(isolate, "FileHandleReqWrap");
@@ -2318,7 +2320,7 @@ void Initialize(Local<Object> target,
       FIXED_ONE_BYTE_STRING(isolate, "FSReqPromise");
   fpt->SetClassName(promiseString);
   Local<ObjectTemplate> fpo = fpt->InstanceTemplate();
-  fpo->SetInternalFieldCount(1);
+  fpo->SetInternalFieldCount(FSReqBase::kInternalFieldCount);
   env->set_fsreqpromise_constructor_template(fpo);
 
   // Create FunctionTemplate for FileHandle
@@ -2327,7 +2329,7 @@ void Initialize(Local<Object> target,
   env->SetProtoMethod(fd, "close", FileHandle::Close);
   env->SetProtoMethod(fd, "releaseFD", FileHandle::ReleaseFD);
   Local<ObjectTemplate> fdt = fd->InstanceTemplate();
-  fdt->SetInternalFieldCount(StreamBase::kStreamBaseFieldCount);
+  fdt->SetInternalFieldCount(StreamBase::kInternalFieldCount);
   Local<String> handleString =
        FIXED_ONE_BYTE_STRING(isolate, "FileHandle");
   fd->SetClassName(handleString);
@@ -2344,7 +2346,7 @@ void Initialize(Local<Object> target,
                         "FileHandleCloseReq"));
   fdclose->Inherit(AsyncWrap::GetConstructorTemplate(env));
   Local<ObjectTemplate> fdcloset = fdclose->InstanceTemplate();
-  fdcloset->SetInternalFieldCount(1);
+  fdcloset->SetInternalFieldCount(FSReqBase::kInternalFieldCount);
   env->set_fdclose_constructor_template(fdcloset);
 
   Local<Symbol> use_promises_symbol =

src/node_http2.cc

@@ -3025,14 +3025,14 @@ void Initialize(Local<Object> target,
   ping->SetClassName(FIXED_ONE_BYTE_STRING(env->isolate(), "Http2Ping"));
   ping->Inherit(AsyncWrap::GetConstructorTemplate(env));
   Local<ObjectTemplate> pingt = ping->InstanceTemplate();
-  pingt->SetInternalFieldCount(1);
+  pingt->SetInternalFieldCount(Http2Session::Http2Ping::kInternalFieldCount);
   env->set_http2ping_constructor_template(pingt);
 
   Local<FunctionTemplate> setting = FunctionTemplate::New(env->isolate());
   setting->SetClassName(FIXED_ONE_BYTE_STRING(env->isolate(), "Http2Setting"));
   setting->Inherit(AsyncWrap::GetConstructorTemplate(env));
   Local<ObjectTemplate> settingt = setting->InstanceTemplate();
-  settingt->SetInternalFieldCount(1);
+  settingt->SetInternalFieldCount(AsyncWrap::kInternalFieldCount);
   env->set_http2settings_constructor_template(settingt);
 
   Local<FunctionTemplate> stream = FunctionTemplate::New(env->isolate());
@@ -3049,7 +3049,7 @@ void Initialize(Local<Object> target,
   stream->Inherit(AsyncWrap::GetConstructorTemplate(env));
   StreamBase::AddMethods(env, stream);
   Local<ObjectTemplate> streamt = stream->InstanceTemplate();
-  streamt->SetInternalFieldCount(StreamBase::kStreamBaseFieldCount);
+  streamt->SetInternalFieldCount(StreamBase::kInternalFieldCount);
   env->set_http2stream_constructor_template(streamt);
   target->Set(context,
               FIXED_ONE_BYTE_STRING(env->isolate(), "Http2Stream"),
@@ -3058,7 +3058,8 @@ void Initialize(Local<Object> target,
   Local<FunctionTemplate> session =
       env->NewFunctionTemplate(Http2Session::New);
   session->SetClassName(http2SessionClassName);
-  session->InstanceTemplate()->SetInternalFieldCount(1);
+  session->InstanceTemplate()->SetInternalFieldCount(
+      Http2Session::kInternalFieldCount);
   session->Inherit(AsyncWrap::GetConstructorTemplate(env));
   env->SetProtoMethod(session, "origin", Http2Session::Origin);
   env->SetProtoMethod(session, "altsvc", Http2Session::AltSvc);

src/node_http_parser.cc

@@ -873,7 +873,7 @@ void InitializeHttpParser(Local<Object> target,
                           void* priv) {
   Environment* env = Environment::GetCurrent(context);
   Local<FunctionTemplate> t = env->NewFunctionTemplate(Parser::New);
-  t->InstanceTemplate()->SetInternalFieldCount(1);
+  t->InstanceTemplate()->SetInternalFieldCount(Parser::kInternalFieldCount);
   t->SetClassName(FIXED_ONE_BYTE_STRING(env->isolate(), "HTTPParser"));
 
   t->Set(FIXED_ONE_BYTE_STRING(env->isolate(), "REQUEST"),

src/node_i18n.cc

@@ -172,7 +172,7 @@ class ConverterObject : public BaseObject, Converter {
     HandleScope scope(env->isolate());
 
     Local<ObjectTemplate> t = ObjectTemplate::New(env->isolate());
-    t->SetInternalFieldCount(1);
+    t->SetInternalFieldCount(ConverterObject::kInternalFieldCount);
     Local<Object> obj;
     if (!t->NewInstance(env->context()).ToLocal(&obj)) return;
 

src/node_messaging.cc

@@ -935,7 +935,8 @@ Local<FunctionTemplate> GetMessagePortConstructorTemplate(Environment* env) {
   {
     Local<FunctionTemplate> m = env->NewFunctionTemplate(MessagePort::New);
     m->SetClassName(env->message_port_constructor_string());
-    m->InstanceTemplate()->SetInternalFieldCount(1);
+    m->InstanceTemplate()->SetInternalFieldCount(
+        MessagePort::kInternalFieldCount);
     m->Inherit(HandleWrap::GetConstructorTemplate(env));
 
     env->SetProtoMethod(m, "postMessage", MessagePort::PostMessage);

src/node_perf.cc

@@ -640,7 +640,8 @@ void Initialize(Local<Object> target,
   Local<FunctionTemplate> eldh =
       env->NewFunctionTemplate(ELDHistogramNew);
   eldh->SetClassName(eldh_classname);
-  eldh->InstanceTemplate()->SetInternalFieldCount(1);
+  eldh->InstanceTemplate()->SetInternalFieldCount(
+      ELDHistogram::kInternalFieldCount);
   env->SetProtoMethod(eldh, "exceeds", ELDHistogramExceeds);
   env->SetProtoMethod(eldh, "min", ELDHistogramMin);
   env->SetProtoMethod(eldh, "max", ELDHistogramMax);

src/node_serdes.cc

@@ -451,7 +451,8 @@ void Initialize(Local<Object> target,
   Local<FunctionTemplate> ser =
       env->NewFunctionTemplate(SerializerContext::New);
 
-  ser->InstanceTemplate()->SetInternalFieldCount(1);
+  ser->InstanceTemplate()->SetInternalFieldCount(
+      SerializerContext::kInternalFieldCount);
 
   env->SetProtoMethod(ser, "writeHeader", SerializerContext::WriteHeader);
   env->SetProtoMethod(ser, "writeValue", SerializerContext::WriteValue);
@@ -477,7 +478,8 @@ void Initialize(Local<Object> target,
   Local<FunctionTemplate> des =
       env->NewFunctionTemplate(DeserializerContext::New);
 
-  des->InstanceTemplate()->SetInternalFieldCount(1);
+  des->InstanceTemplate()->SetInternalFieldCount(
+      DeserializerContext::kInternalFieldCount);
 
   env->SetProtoMethod(des, "readHeader", DeserializerContext::ReadHeader);
   env->SetProtoMethod(des, "readValue", DeserializerContext::ReadValue);

src/node_stat_watcher.cc

@@ -47,7 +47,8 @@ void StatWatcher::Initialize(Environment* env, Local<Object> target) {
   HandleScope scope(env->isolate());
 
   Local<FunctionTemplate> t = env->NewFunctionTemplate(StatWatcher::New);
-  t->InstanceTemplate()->SetInternalFieldCount(1);
+  t->InstanceTemplate()->SetInternalFieldCount(
+      StatWatcher::kInternalFieldCount);
   Local<String> statWatcherString =
       FIXED_ONE_BYTE_STRING(env->isolate(), "StatWatcher");
   t->SetClassName(statWatcherString);

src/node_trace_events.cc

@@ -129,7 +129,8 @@ void NodeCategorySet::Initialize(Local<Object> target,
 
   Local<FunctionTemplate> category_set =
       env->NewFunctionTemplate(NodeCategorySet::New);
-  category_set->InstanceTemplate()->SetInternalFieldCount(1);
+  category_set->InstanceTemplate()->SetInternalFieldCount(
+      NodeCategorySet::kInternalFieldCount);
   env->SetProtoMethod(category_set, "enable", NodeCategorySet::Enable);
   env->SetProtoMethod(category_set, "disable", NodeCategorySet::Disable);
 

src/node_util.cc

@@ -323,7 +323,8 @@ void Initialize(Local<Object> target,
       FIXED_ONE_BYTE_STRING(env->isolate(), "WeakReference");
   Local<FunctionTemplate> weak_ref =
       env->NewFunctionTemplate(WeakReference::New);
-  weak_ref->InstanceTemplate()->SetInternalFieldCount(1);
+  weak_ref->InstanceTemplate()->SetInternalFieldCount(
+      WeakReference::kInternalFieldCount);
   weak_ref->SetClassName(weak_ref_string);
   env->SetProtoMethod(weak_ref, "get", WeakReference::Get);
   env->SetProtoMethod(weak_ref, "incRef", WeakReference::IncRef);

src/node_wasi.cc

@@ -1810,7 +1810,7 @@ static void Initialize(Local<Object> target,
 
   Local<FunctionTemplate> tmpl = env->NewFunctionTemplate(WASI::New);
   auto wasi_wrap_string = FIXED_ONE_BYTE_STRING(env->isolate(), "WASI");
-  tmpl->InstanceTemplate()->SetInternalFieldCount(1);
+  tmpl->InstanceTemplate()->SetInternalFieldCount(WASI::kInternalFieldCount);
   tmpl->SetClassName(wasi_wrap_string);
 
   env->SetProtoMethod(tmpl, "args_get", WASI::ArgsGet);

src/node_watchdog.cc

@@ -121,7 +121,8 @@ SignalPropagation SigintWatchdog::HandleSigint() {
 
 void TraceSigintWatchdog::Init(Environment* env, Local<Object> target) {
   Local<FunctionTemplate> constructor = env->NewFunctionTemplate(New);
-  constructor->InstanceTemplate()->SetInternalFieldCount(1);
+  constructor->InstanceTemplate()->SetInternalFieldCount(
+      TraceSigintWatchdog::kInternalFieldCount);
   Local<v8::String> js_sigint_watch_dog =
       FIXED_ONE_BYTE_STRING(env->isolate(), "TraceSigintWatchdog");
   constructor->SetClassName(js_sigint_watch_dog);

src/node_worker.cc

@@ -776,7 +776,8 @@ void InitWorker(Local<Object> target,
   {
     Local<FunctionTemplate> w = env->NewFunctionTemplate(Worker::New);
 
-    w->InstanceTemplate()->SetInternalFieldCount(1);
+    w->InstanceTemplate()->SetInternalFieldCount(
+        Worker::kInternalFieldCount);
     w->Inherit(AsyncWrap::GetConstructorTemplate(env));
 
     env->SetProtoMethod(w, "startThread", Worker::StartThread);
@@ -797,7 +798,8 @@ void InitWorker(Local<Object> target,
   {
     Local<FunctionTemplate> wst = FunctionTemplate::New(env->isolate());
 
-    wst->InstanceTemplate()->SetInternalFieldCount(1);
+    wst->InstanceTemplate()->SetInternalFieldCount(
+        WorkerHeapSnapshotTaker::kInternalFieldCount);
     wst->Inherit(AsyncWrap::GetConstructorTemplate(env));
 
     Local<String> wst_string =

src/node_zlib.cc

@@ -1216,7 +1216,8 @@ struct MakeClass {
   static void Make(Environment* env, Local<Object> target, const char* name) {
     Local<FunctionTemplate> z = env->NewFunctionTemplate(Stream::New);
 
-    z->InstanceTemplate()->SetInternalFieldCount(1);
+    z->InstanceTemplate()->SetInternalFieldCount(
+        Stream::kInternalFieldCount);
     z->Inherit(AsyncWrap::GetConstructorTemplate(env));
 
     env->SetProtoMethod(z, "write", Stream::template Write<true>);

src/pipe_wrap.cc

@@ -74,7 +74,7 @@ void PipeWrap::Initialize(Local<Object> target,
   Local<String> pipeString = FIXED_ONE_BYTE_STRING(env->isolate(), "Pipe");
   t->SetClassName(pipeString);
   t->InstanceTemplate()
-    ->SetInternalFieldCount(StreamBase::kStreamBaseFieldCount);
+    ->SetInternalFieldCount(StreamBase::kInternalFieldCount);
 
   t->Inherit(LibuvStreamWrap::GetConstructorTemplate(env));
 

src/process_wrap.cc

@@ -52,7 +52,8 @@ class ProcessWrap : public HandleWrap {
                          void* priv) {
     Environment* env = Environment::GetCurrent(context);
     Local<FunctionTemplate> constructor = env->NewFunctionTemplate(New);
-    constructor->InstanceTemplate()->SetInternalFieldCount(1);
+    constructor->InstanceTemplate()->SetInternalFieldCount(
+        ProcessWrap::kInternalFieldCount);
     Local<String> processString =
         FIXED_ONE_BYTE_STRING(env->isolate(), "Process");
     constructor->SetClassName(processString);

src/signal_wrap.cc

@@ -53,7 +53,8 @@ class SignalWrap : public HandleWrap {
                          void* priv) {
     Environment* env = Environment::GetCurrent(context);
     Local<FunctionTemplate> constructor = env->NewFunctionTemplate(New);
-    constructor->InstanceTemplate()->SetInternalFieldCount(1);
+    constructor->InstanceTemplate()->SetInternalFieldCount(
+        SignalWrap::kInternalFieldCount);
     Local<String> signalString =
         FIXED_ONE_BYTE_STRING(env->isolate(), "Signal");
     constructor->SetClassName(signalString);

src/stream_base-inl.h

@@ -23,18 +23,22 @@ using v8::String;
 using v8::Value;
 
 inline void StreamReq::AttachToObject(v8::Local<v8::Object> req_wrap_obj) {
-  CHECK_EQ(req_wrap_obj->GetAlignedPointerFromInternalField(kStreamReqField),
+  CHECK_EQ(req_wrap_obj->GetAlignedPointerFromInternalField(
+               StreamReq::kStreamReqField),
            nullptr);
-  req_wrap_obj->SetAlignedPointerInInternalField(kStreamReqField, this);
+  req_wrap_obj->SetAlignedPointerInInternalField(
+      StreamReq::kStreamReqField, this);
 }
 
 inline StreamReq* StreamReq::FromObject(v8::Local<v8::Object> req_wrap_obj) {
   return static_cast<StreamReq*>(
-      req_wrap_obj->GetAlignedPointerFromInternalField(kStreamReqField));
+      req_wrap_obj->GetAlignedPointerFromInternalField(
+          StreamReq::kStreamReqField));
 }
 
 inline void StreamReq::Dispose() {
-  object()->SetAlignedPointerInInternalField(kStreamReqField, nullptr);
+  object()->SetAlignedPointerInInternalField(
+      StreamReq::kStreamReqField, nullptr);
   delete this;
 }
 
@@ -261,15 +265,17 @@ inline WriteWrap* StreamBase::CreateWriteWrap(
 }
 
 inline void StreamBase::AttachToObject(v8::Local<v8::Object> obj) {
-  obj->SetAlignedPointerInInternalField(kStreamBaseField, this);
+  obj->SetAlignedPointerInInternalField(
+      StreamBase::kStreamBaseField, this);
 }
 
 inline StreamBase* StreamBase::FromObject(v8::Local<v8::Object> obj) {
-  if (obj->GetAlignedPointerFromInternalField(0) == nullptr)
+  if (obj->GetAlignedPointerFromInternalField(StreamBase::kSlot) == nullptr)
     return nullptr;
 
   return static_cast<StreamBase*>(
-      obj->GetAlignedPointerFromInternalField(kStreamBaseField));
+      obj->GetAlignedPointerFromInternalField(
+          StreamBase::kStreamBaseField));
 }
 
 
@@ -304,7 +310,7 @@ inline void StreamReq::Done(int status, const char* error_str) {
 inline void StreamReq::ResetObject(v8::Local<v8::Object> obj) {
   DCHECK_GT(obj->InternalFieldCount(), StreamReq::kStreamReqField);
 
-  obj->SetAlignedPointerInInternalField(0, nullptr);  // BaseObject field.
+  obj->SetAlignedPointerInInternalField(StreamReq::kSlot, nullptr);
   obj->SetAlignedPointerInInternalField(StreamReq::kStreamReqField, nullptr);
 }
 

src/stream_base.cc

@@ -340,7 +340,8 @@ MaybeLocal<Value> StreamBase::CallJSOnreadMethod(ssize_t nread,
 
   AsyncWrap* wrap = GetAsyncWrap();
   CHECK_NOT_NULL(wrap);
-  Local<Value> onread = wrap->object()->GetInternalField(kOnReadFunctionField);
+  Local<Value> onread = wrap->object()->GetInternalField(
+      StreamBase::kOnReadFunctionField);
   CHECK(onread->IsFunction());
   return wrap->MakeCallback(onread.As<Function>(), arraysize(argv), argv);
 }
@@ -409,8 +410,11 @@ void StreamBase::AddMethods(Environment* env, Local<FunctionTemplate> t) {
                               True(env->isolate()));
   t->PrototypeTemplate()->SetAccessor(
       FIXED_ONE_BYTE_STRING(env->isolate(), "onread"),
-      BaseObject::InternalFieldGet<kOnReadFunctionField>,
+      BaseObject::InternalFieldGet<
-      BaseObject::InternalFieldSet<kOnReadFunctionField, &Value::IsFunction>);
+          StreamBase::kOnReadFunctionField>,
+      BaseObject::InternalFieldSet<
+          StreamBase::kOnReadFunctionField,
+          &Value::IsFunction>);
 }
 
 void StreamBase::GetFD(const FunctionCallbackInfo<Value>& args) {

src/stream_base.h

@@ -29,7 +29,14 @@ using JSMethodFunction = void(const v8::FunctionCallbackInfo<v8::Value>& args);
 
 class StreamReq {
  public:
-  static constexpr int kStreamReqField = 1;
+  // The kSlot internal field here mirrors BaseObject::InternalFields::kSlot
+  // here because instances derived from StreamReq will also derive from
+  // BaseObject, and the slots are used for the identical purpose.
+  enum InternalFields {
+    kSlot = BaseObject::kSlot,
+    kStreamReqField = BaseObject::kInternalFieldCount,
+    kInternalFieldCount
+  };
 
   explicit StreamReq(StreamBase* stream,
                      v8::Local<v8::Object> req_wrap_obj) : stream_(stream) {
@@ -275,10 +282,15 @@ class StreamResource {
 
 class StreamBase : public StreamResource {
  public:
-  // 0 is reserved for the BaseObject pointer.
+  // The kSlot field here mirrors that of BaseObject::InternalFields::kSlot
-  static constexpr int kStreamBaseField = 1;
+  // because instances deriving from StreamBase generally also derived from
-  static constexpr int kOnReadFunctionField = 2;
+  // BaseObject (it's possible for it not to, however).
-  static constexpr int kStreamBaseFieldCount = 3;
+  enum InternalFields {
+    kSlot = BaseObject::kSlot,
+    kStreamBaseField = BaseObject::kInternalFieldCount,
+    kOnReadFunctionField,
+    kInternalFieldCount
+  };
 
   static void AddMethods(Environment* env,
                          v8::Local<v8::FunctionTemplate> target);

src/stream_pipe.cc

@@ -298,7 +298,8 @@ void InitializeStreamPipe(Local<Object> target,
   env->SetProtoMethod(pipe, "pendingWrites", StreamPipe::PendingWrites);
   pipe->Inherit(AsyncWrap::GetConstructorTemplate(env));
   pipe->SetClassName(stream_pipe_string);
-  pipe->InstanceTemplate()->SetInternalFieldCount(1);
+  pipe->InstanceTemplate()->SetInternalFieldCount(
+      StreamPipe::kInternalFieldCount);
   target
       ->Set(context, stream_pipe_string,
             pipe->GetFunction(context).ToLocalChecked())

src/stream_wrap.cc

@@ -64,8 +64,7 @@ void LibuvStreamWrap::Initialize(Local<Object> target,
   };
   Local<FunctionTemplate> sw =
       FunctionTemplate::New(env->isolate(), is_construct_call_callback);
-  sw->InstanceTemplate()->SetInternalFieldCount(
+  sw->InstanceTemplate()->SetInternalFieldCount(StreamReq::kInternalFieldCount);
-      StreamReq::kStreamReqField + 1 + 3);
   Local<String> wrapString =
       FIXED_ONE_BYTE_STRING(env->isolate(), "ShutdownWrap");
   sw->SetClassName(wrapString);
@@ -94,7 +93,8 @@ void LibuvStreamWrap::Initialize(Local<Object> target,
 
   Local<FunctionTemplate> ww =
       FunctionTemplate::New(env->isolate(), is_construct_call_callback);
-  ww->InstanceTemplate()->SetInternalFieldCount(StreamReq::kStreamReqField + 1);
+  ww->InstanceTemplate()->SetInternalFieldCount(
+      StreamReq::kInternalFieldCount);
   Local<String> writeWrapString =
       FIXED_ONE_BYTE_STRING(env->isolate(), "WriteWrap");
   ww->SetClassName(writeWrapString);
@@ -136,7 +136,7 @@ Local<FunctionTemplate> LibuvStreamWrap::GetConstructorTemplate(
         FIXED_ONE_BYTE_STRING(env->isolate(), "LibuvStreamWrap"));
     tmpl->Inherit(HandleWrap::GetConstructorTemplate(env));
     tmpl->InstanceTemplate()->SetInternalFieldCount(
-        StreamBase::kStreamBaseFieldCount);
+        StreamBase::kInternalFieldCount);
     Local<FunctionTemplate> get_write_queue_size =
         FunctionTemplate::New(env->isolate(),
                               GetWriteQueueSize,

src/tcp_wrap.cc

@@ -77,8 +77,7 @@ void TCPWrap::Initialize(Local<Object> target,
   Local<FunctionTemplate> t = env->NewFunctionTemplate(New);
   Local<String> tcpString = FIXED_ONE_BYTE_STRING(env->isolate(), "TCP");
   t->SetClassName(tcpString);
-  t->InstanceTemplate()
+  t->InstanceTemplate()->SetInternalFieldCount(StreamBase::kInternalFieldCount);
-    ->SetInternalFieldCount(StreamBase::kStreamBaseFieldCount);
 
   // Init properties
   t->InstanceTemplate()->Set(FIXED_ONE_BYTE_STRING(env->isolate(), "reading"),

src/tls_wrap.cc

@@ -1269,8 +1269,7 @@ void TLSWrap::Initialize(Local<Object> target,
   Local<String> tlsWrapString =
       FIXED_ONE_BYTE_STRING(env->isolate(), "TLSWrap");
   t->SetClassName(tlsWrapString);
-  t->InstanceTemplate()
+  t->InstanceTemplate()->SetInternalFieldCount(StreamBase::kInternalFieldCount);
-    ->SetInternalFieldCount(StreamBase::kStreamBaseFieldCount);
 
   Local<FunctionTemplate> get_write_queue_size =
       FunctionTemplate::New(env->isolate(),

src/tty_wrap.cc

@@ -51,8 +51,7 @@ void TTYWrap::Initialize(Local<Object> target,
 
   Local<FunctionTemplate> t = env->NewFunctionTemplate(New);
   t->SetClassName(ttyString);
-  t->InstanceTemplate()
+  t->InstanceTemplate()->SetInternalFieldCount(StreamBase::kInternalFieldCount);
-    ->SetInternalFieldCount(StreamBase::kStreamBaseFieldCount);
   t->Inherit(LibuvStreamWrap::GetConstructorTemplate(env));
 
   env->SetProtoMethodNoSideEffect(t, "getWindowSize", TTYWrap::GetWindowSize);

src/udp_wrap.cc

@@ -91,7 +91,7 @@ void UDPWrap::Initialize(Local<Object> target,
   Environment* env = Environment::GetCurrent(context);
 
   Local<FunctionTemplate> t = env->NewFunctionTemplate(New);
-  t->InstanceTemplate()->SetInternalFieldCount(1);
+  t->InstanceTemplate()->SetInternalFieldCount(UDPWrap::kInternalFieldCount);
   Local<String> udpString =
       FIXED_ONE_BYTE_STRING(env->isolate(), "UDP");
   t->SetClassName(udpString);