[v8-users] IsFunction() on v8::Name returns false

[Gautham B A]

Hi all,

Calling IsFunction() on v8::Local<v8::Name> is returning false, even though 
v8::Local<v8::Name> was pointing to a function in JavaScript. Is this 
expected? Consider the following code -

#include <iostream>
#include <libplatform/libplatform.h>
#include <ostream>
#include <v8.h>


void Getter(v8::Local<v8::Name> key,
            const v8::PropertyCallbackInfo<v8::Value> &info) {
  std::cout << "Getter:" << std::endl;
  std::cout << "IsFunction: " << key->IsFunction() << std::endl;
}


void Setter(v8::Local<v8::Name> key, v8::Local<v8::Value> value,
            const v8::PropertyCallbackInfo<v8::Value> &info) {
  std::cout << "Setter:" << std::endl;
  // key->IsFunction() returns false, expected to be true
  std::cout << "Key IsFunction: " << key->IsFunction() << std::endl;


  // value->IsFunction() returns true, as expected
  std::cout << "\nValue IsFunction:" << value->IsFunction() << std::endl;
}


void Deleter(v8::Local<v8::Name> key,
             const v8::PropertyCallbackInfo<v8::Boolean> &info) {}


bool InstallMap(v8::Isolate *isolate, const v8::Local<v8::Context> &context) 
{
  v8::HandleScope handle_scope(isolate);
  auto obj_template = v8::ObjectTemplate::New(isolate);
  obj_template->SetHandler(
      v8::NamedPropertyHandlerConfiguration(Getter, Setter, nullptr, Deleter
));


  v8::Local<v8::Object> obj;
  if (!obj_template->NewInstance(context).ToLocal(&obj)) {
    std::cerr << "Unable to instantiate object template" << std::endl;
    return false;
  }


  v8::Local<v8::String> obj_name;
  if (!v8::String::NewFromUtf8(isolate, "dict", v8::String::kNormalString)
           ->ToString(context)
           .ToLocal(&obj_name)) {
    std::cerr << "Unable to create map key name" << std::endl;
    return false;
  }


  auto global = context->Global();
  if (!global->Set(context, obj_name, obj).FromJust()) {
    std::cerr << "Unable to install object into global scope" << std::endl;
    return false;
  }
  return true;
}


int main(int argc, char *argv[]) {
  const auto script_str = R"(
  function x() {
  }


  dict[x] = x;
  )";


  v8::V8::InitializeICUDefaultLocation(argv[0]);
  v8::V8::InitializeExternalStartupData(argv[0]);
  auto platform = v8::platform::NewDefaultPlatform();
  v8::V8::InitializePlatform(platform.get());
  v8::V8::Initialize();


  v8::Isolate::CreateParams create_params;
  create_params.array_buffer_allocator =
      v8::ArrayBuffer::Allocator::NewDefaultAllocator();
  v8::Isolate *isolate = v8::Isolate::New(create_params);
  {
    v8::Isolate::Scope isolate_scope(isolate);
    v8::HandleScope handle_scope(isolate);
    auto context = v8::Context::New(isolate);
    v8::Context::Scope context_scope(context);


    InstallMap(isolate, context);


    auto source =
        v8::String::NewFromUtf8(isolate, script_str, v8::NewStringType::
kNormal)
            .ToLocalChecked();
    auto script = v8::Script::Compile(context, source).ToLocalChecked();
    auto result = script->Run(context).ToLocalChecked();
    v8::String::Utf8Value result_utf8(isolate, result);
    std::cout << *result_utf8 << std::endl;
  }
  isolate->Dispose();
  v8::V8::Dispose();
  v8::V8::ShutdownPlatform();
  delete create_params.array_buffer_allocator;
  return 0;
}


As seen in the code above, I'm exposing a global variable dict which has 
the Setter, Getter and Deleter callbacks set appropriately on dict.

function x() {
}
dict[x] = x;
When I run the above JavaScript code, The Setter callback gets called and I 
see that *name* and *value* have different results upon calling 
IsFunction() on them.
Could someone please tell me if this is the expected behavior, if so, the 
reason behind why it is so?

Thanks,
--Gautham

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