https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98077
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|WAITING |NEW
Keywords| |rejects-valid
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The testcase from the godbolt link is:
// { dg-options "-std=gnu++17" }
#include <functional>
template <typename T>
struct CallableTrait;
template <typename R, typename... Args>
struct CallableTrait<std::function<R(Args...)>>
{
using ReturnType = R;
};
template <typename Callable>
using CallableTraitT =
CallableTrait<decltype(std::function{std::declval<Callable>()})>;
template <typename Callable>
auto test(Callable&&)
{
using CallableInfo = CallableTraitT<Callable>;
static_assert(!std::is_void_v<typename CallableInfo::ReturnType>);
}
int main()
{
test([]() { return 42; });
}
It requires at least C++17.
