Thanks, in type_alias document I see the example: template<class T> using Vec = vector<T, Alloc<T>>; // type-id is vector<T, Alloc<T>> Vec<int> v

Thanks, in type_alias document I see the example: template<class T> using Vec = vector<T, Alloc<T>>; // type-id is vector<T, Alloc<T>> Vec<int> v; // Vec<int> is the same as vector<int, Alloc<int>> That explains to me the using construct. And tcbawo's answer tries to address the U{}.func() However "either of which could apply to U{}" ... I'd expect that it should be possible to say which of these is in this example? I also can't see how that can (or should?) match "aggregate_initialization."