https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109899
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> --- A little further reduced: ``` struct class1 { class1(); ~class1(); }; template <typename T> using array = T[1]; template <int N> auto f1() -> decltype(sizeof(array<class1>{})); ```