public:
const_iterator() = default;
// Placate MSVC by explicitly scoping 'iterator'.
- const_iterator(IntrusiveBackList::iterator X) : N(X.N) {}
+ const_iterator(typename IntrusiveBackList<T>::iterator X) : N(X.N) {}
explicit const_iterator(const T *N) : N(N) {}
const_iterator &operator++() {