Function signature_error_values

test/stdexec/concepts/test_awaitables.cpp:220–226

  template <typename Error, typename... Values>
  auto
  signature_error_values(Error, Values...) -> ex::completion_signatures<ex::set_value_t(Values...),
                                                                        ex::set_error_t(Error),
                                                                        ex::set_stopped_t()>*
  {
    return {};
  }

  TEST_CASE("get completion_signatures for awaitables", "[sndtraits][awaitables]")
  {