[Bug c++/86356] "invalid use of pack expansion" with fold expressions

[ensadc at mailnesia dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86356

ensadc at mailnesia dot com changed:

           What    |Removed                     |Added
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                 CC|                            |ensadc at mailnesia dot com

--- Comment #1 from ensadc at mailnesia dot com ---
Reduced:

template<bool B> struct mp_bool { static constexpr bool value = B; };

template<class... T> using mp_any =
  mp_bool<(static_cast<bool>(T::value) || ...)>;

template<class T>
struct A { static constexpr bool value = true; };

template<bool> struct variant_base_impl {};
template<class... T> using variant_base
  = variant_base_impl<mp_any<mp_bool<true>, A<T>...>::value>;

int main()
{
        variant_base<int>();
}