tmp.cc

#include <stdio.h>

class Signature;
class FunctionTemplate;

template <class V8Type>
class Local {
 public:
//    Local(const char* x, Local<FunctionTemplate> y):
//       val_(nullptr), realval_(x, y) {}
//    Local(int x, Local<Signature> y):
//       val_(nullptr), realval_(x, y) {}
  Local(): val_(nullptr) {}
  ~Local() {
    delete val_;
  }
 private:
  friend class Signature;
  friend class FunctionTemplate;
  explicit inline Local(V8Type* that) : val_(that) {}
  V8Type* val_;
//   V8Type realval_;
};

class Signature {
 public:
  inline Signature() {}
  inline Signature(const char* x, Local<FunctionTemplate> tpl) {}
  static inline Local<Signature> New(const char* x,
      Local<FunctionTemplate> y = Local<FunctionTemplate>()) {
    // return Local<Signature>(x, y);
    return Local<Signature>(new Signature(x, y));
  }
  
};

class FunctionTemplate {
 public:
  inline FunctionTemplate() {}
  inline FunctionTemplate(int x, Local<Signature> y) {}
  static inline Local<FunctionTemplate> New(int x,
      Local<Signature> y = Local<Signature>()) {
    // return Local<FunctionTemplate>(x, y);
    return Local<FunctionTemplate>(new FunctionTemplate(x, y));
  }
};

int main() {
  auto a = FunctionTemplate::New(5);
  auto b = Signature::New("abc");
  return 0;
}

// tmp.cc: In instantiation of 'class Local<FunctionTemplate>':
// tmp.cc:9:51:   required from here
// tmp.cc:22:10: error: 'Local<V8Type>::realval_' has incomplete type
//    V8Type realval_;
//           ^~~~~~~~
// tmp.cc:4:7: note: forward declaration of 'class FunctionTemplate'
//  class FunctionTemplate;
//        ^~~~~~~~~~~~~~~~
// tmp.cc: In instantiation of 'class Local<Signature>':
// tmp.cc:11:36:   required from here
// tmp.cc:22:10: error: 'Local<V8Type>::realval_' has incomplete type
//    V8Type realval_;
//           ^~~~~~~~
// tmp.cc:3:7: note: forward declaration of 'class Signature'
//  class Signature;
//        ^~~~~~~~~