bad_error.c++

#include <tuple>
#include <type_traits>

template <int... I>
using bar = std::tuple<std::integral_constant<int, I>...>;

template <int... I>
struct foo {
    int total(bar<I...> const&) const { return 0; } // error C3520: 'I' : parameter pack must be expanded in this context
};

ice.c++

#include <tuple>
#include <type_traits>

template <int... I>
using bar = std::tuple<std::integral_constant<int, I>...>;

template <bool X, int... I>
struct foo {
    int total(bar<I...> const&) const { return 0; } // fatal error C1001: An internal error has occurred in the compiler.
};