https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61341
--- Comment #1 from Ivan Sorokin <vanyacpp at gmail dot com> --- Reduced case: template<class ...T> struct X {}; template<class ...T> void foo(X<T, T...>... a); void test() { foo(X<int, int, double>(), X<double, int, double>()); }