gcc/testsuite/g++.dg/coroutines/coro-missing-ret-value.C

//  { dg-additional-options "-fsyntax-only -w" }

// Diagose missing return_value() in the promise type.

#include "coro.h"

struct MissingRetValue {
  coro::coroutine_handle<> handle;
  MissingRetValue () : handle (nullptr) {}
  MissingRetValue (coro::coroutine_handle<> handle) : handle (handle) {}
  struct missing_retvoid {
    coro::suspend_never initial_suspend() { return {}; }
    coro::suspend_never final_suspend() noexcept { return {}; }
    MissingRetValue get_return_object() {
      return MissingRetValue (coro::coroutine_handle<missing_retvoid>::from_promise (*this));
    }
    void unhandled_exception() { /*std::terminate();*/ };
  };
};

template<> struct coro::coroutine_traits<MissingRetValue> {
    using promise_type = MissingRetValue::missing_retvoid;
};

MissingRetValue
bar ()
{
  co_return 6174; // { dg-error {no member named 'return_value' in} }
}

// check we have not messed up continuation of the compilation.
template <class... Args>
struct void_t_imp {
  using type = void;
};

int main (int ac, char *av[]) {
  MissingRetValue x = bar ();
  return 0;
}