https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99650
Jakub Jelinek <jakub at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |jakub at gcc dot gnu.org --- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> --- cvise reduced into: template <int a> struct b { static constexpr int value = a; }; template <typename c> c e(long); template <typename c> auto d() -> decltype(e<c>(0)); template <typename> struct tuple_size; template <unsigned long, typename> struct tuple_element; template <typename...> struct l { template <int> void get(); }; l<int, int, int, void> f; template <typename... g> struct tuple_size<l<g...>> : b<sizeof... (g)> {}; template <unsigned long m, class... g> struct tuple_element<m, l<g...>> { using type = decltype(d<l<>>().get<m>()); }; auto [h, i, j, k] = f; Another testcase that ICEs the same way: namespace std { template<typename T> struct tuple_size; template<int, typename> struct tuple_element; } struct A { int i; template <int I> void get() { } }; template<> struct std::tuple_size<A> { static const int value = 2; }; template<int I> struct std::tuple_element<I,A> { using type = void; }; A a = { 42 }; auto [ x, y ] = a;