https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103186
--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Reduced testcase for the first issue (note it is a different error but the problem is the same): using Callback = void(); template <typename ValueType> struct GetSetHelper { static void set( Callback callback_ = []() {} ){} }; template <typename First> void m() { GetSetHelper<First>::set(); } template <typename... Types> void n( ) { ( ( m<Types>( ) ), ... ); } int main() { GetSetHelper<signed>::set(); n<signed, unsigned>( ); }