https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78550
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Started with r230365. Testcase without any headers: namespace std { template <class T> struct initializer_list { const T *a; __SIZE_TYPE__ b; constexpr initializer_list (const T *x, __SIZE_TYPE__ y) : a(x), b(y) { } }; } template <typename T> struct A { A (std::initializer_list<T>); }; struct B { int k : 1; }; A<B> a{{0}};