https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77825
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2016-10-05
Known to work| |5.4.0, 6.2.0
Summary|return type deduction |[7 Regression] return type
|regression in 7.0 |deduction regression in
| |C++17 mode
Ever confirmed|0 |1
Known to fail| |7.0
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
template<typename T> struct decay { using type = T; };
template<typename T> struct decay<T&> { using type = T; };
template<typename T> struct decay<T&&> { using type = T; };
template<typename T> using decay_t = typename decay<T>::type;
template<typename _Tp>
constexpr _Tp&&
forward(decay_t<_Tp>& __t) noexcept
{ return static_cast<_Tp&&>(__t); }
template <class F>
struct y_combinator {
F f;
template <class... Args>
decltype(auto) operator()(Args&&... args) const
{
return f(*this, forward<Args>(args)...);
}
};
template <class F>
y_combinator<decay_t<F>> make_y_combinator(F&& f) {
return {forward<F>(f)};
}
int main() {
auto factorial = make_y_combinator([](auto fact, int n) -> int {
if (n == 0) return 1;
else return n * fact(n - 1);
});
factorial(5);
}
It compiles OK as C++14 but not as C++1z.
