https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95813
Bug ID: 95813
Summary: Making static member function a coroutine may cause
"defined but not used" warning for destroy(frame*)
function
Product: gcc
Version: 10.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: gleb at scylladb dot com
Target Milestone: ---
Compiling the code below with -Wall emits:
warn.cc:37:5: warning: ^Xגvoid
xxx::_ZN3xxx4funcEv.destroy(xxx::func()::_ZN3xxx4funcEv.frame*)^Yג defined but
not used [-Wunused-function]
and if foo() is uncommented the code compiles fine.
If should be OK to have the static member function in a header without getting
the warning.
#include <coroutine>
#include <functional>
#include <optional>
#include <cassert>
template <typename T>
class lazy {
T _v = 0;
public:
lazy() {}
bool await_ready() {return true;}
void await_suspend(auto x) noexcept {}
T await_resume() { return _v; }
};
namespace std {
template <typename T, typename... Args>
struct coroutine_traits<lazy<T>, Args...> {
struct promise_type {
suspend_always initial_suspend() const { return {}; }
suspend_always final_suspend() const { return {}; }
void return_value(T val) {}
lazy<T> get_return_object() {
return lazy<T>();
}
void unhandled_exception() {
std::terminate();
}
};
};
}
struct xxx {
static lazy<int> func() {
co_return 1;
}
};
#if 0
lazy<int> foo() {
co_return co_await xxx::func();
}
#endif
