struct coro1 {

  struct promise_type {

  promise_type () : vv(-1) {  PRINT ("Promise def. CTOR"); }
  promise_type (int __x) : vv(__x) {  PRINTF ("promise_type1 with %d\n",__x); }
  promise_type (int __x, int& __y, int&& __z)
    : vv(__x), v2(__y), v3(__z)
    {  PRINTF ("promise_type2 with %d, %d, %d\n", __x, __y, __z); }
  promise_type (int __x, int& __y, int& __z)
    : vv(__x), v2(__y), v3(__z)
    {  PRINTF ("promise_type3 with %d, %d, %d\n", __x, __y, __z); }

  ~promise_type() { PRINT ("Destroyed Promise"); }

  auto get_return_object () {
    PRINT ("get_return_object: handle from promise");
    return handle_type::from_promise (*this);
  }

  auto initial_suspend () {
    PRINT ("get initial_suspend (always)");
    return suspend_always_prt{};
  }
  auto final_suspend () noexcept {
    PRINT ("get final_suspend (always)");
    return suspend_always_prt{};
  }

#ifdef USE_AWAIT_TRANSFORM

  auto await_transform (int v) {
    PRINTF ("await_transform an int () %d\n",v);
    return suspend_always_intprt (v);
  }

  auto await_transform (long v) {
    PRINTF ("await_transform a long () %ld\n",v);
    return suspend_always_longprtsq (v);
  }

#endif

  auto yield_value (int v) {
    PRINTF ("yield_value (%d)\n", v);
    vv = v;
    return suspend_always_prt{};
  }

  void return_value (int v) {
    PRINTF ("return_value (%d)\n", v);
    vv = v;
    
  }

  void unhandled_exception() { PRINT ("** unhandled exception"); }

  int get_value () { return vv; }
  int get_v2 () { return v2; }
  int get_v3 () { return v3; }

  private:
    int vv;
    int v2;
    int v3;
  };

  using handle_type = coro::coroutine_handle<coro1::promise_type>;
  handle_type handle;
  coro1 () : handle(0) {}
  coro1 (handle_type _handle)
    : handle(_handle) {
        PRINT("Created coro1 object from handle");
  }
  coro1 (const coro1 &) = delete; // no copying
  coro1 (coro1 &&s) : handle(s.handle) {
	s.handle = nullptr;
	PRINT("coro1 mv ctor ");
  }
  coro1 &operator = (coro1 &&s) {
	handle = s.handle;
	s.handle = nullptr;
	PRINT("coro1 op=  ");
	return *this;
  }
  ~coro1() {
        PRINT("Destroyed coro1");
        if ( handle )
          handle.destroy();
  }

  // Some awaitables to use in tests.
  // With progress printing for debug.
  struct suspend_never_prt {
  bool await_ready() const noexcept { return true; }
  void await_suspend(handle_type) const noexcept { PRINT ("susp-never-susp");}
  void await_resume() const noexcept { PRINT ("susp-never-resume");}
  };

  struct  suspend_always_prt {
  bool await_ready() const noexcept { return false; }
  void await_suspend(handle_type) const noexcept { PRINT ("susp-always-susp");}
  void await_resume() const noexcept { PRINT ("susp-always-resume");}
  ~suspend_always_prt() { PRINT ("susp-always-dtor"); }
  };

  struct suspend_always_intprt {
    int x;
    suspend_always_intprt() : x(5) {}
    suspend_always_intprt(int __x) : x(__x) {}
    ~suspend_always_intprt() {}
    bool await_ready() const noexcept { return false; }
    void await_suspend(coro::coroutine_handle<>) const noexcept { PRINT ("susp-always-susp-intprt");}
    int await_resume() const noexcept { PRINT ("susp-always-resume-intprt"); return x;}
  };
  
  /* This returns the square of the int that it was constructed with.  */
  struct suspend_always_longprtsq {
    long x;
    suspend_always_longprtsq() : x(12L) { PRINT ("suspend_always_longprtsq def ctor"); }
    suspend_always_longprtsq(long _x) : x(_x) { PRINTF ("suspend_always_longprtsq ctor with %ld\n", x); }
    ~suspend_always_longprtsq() {}
    bool await_ready() const noexcept { return false; }
    void await_suspend(coro::coroutine_handle<>) const noexcept { PRINT ("susp-always-susp-longsq");}
    long await_resume() const noexcept { PRINT ("susp-always-resume-longsq"); return x * x;}
  };

  struct suspend_always_intrefprt {
    int& x;
    suspend_always_intrefprt(int& __x) : x(__x) {}
    ~suspend_always_intrefprt() {}
    bool await_ready() const noexcept { return false; }
    void await_suspend(coro::coroutine_handle<>) const noexcept { PRINT ("susp-always-susp-intprt");}
    int& await_resume() const noexcept { PRINT ("susp-always-resume-intprt"); return x;}
  };

  template <typename _AwaitType>
  struct suspend_always_tmpl_awaiter {
    _AwaitType x;
    suspend_always_tmpl_awaiter(_AwaitType __x) : x(__x) {}
    ~suspend_always_tmpl_awaiter() {}
    bool await_ready() const noexcept { return false; }
    void await_suspend(coro::coroutine_handle<>) const noexcept { PRINT ("suspend_always_tmpl_awaiter");}
    _AwaitType await_resume() const noexcept { PRINT ("suspend_always_tmpl_awaiter"); return x;}
  };

};