26 Ranges library [ranges]

26.3 Range access [range.access]

26.3.14 ranges​::​cdata [range.prim.cdata]

template<class T> constexpr auto as-const-pointer(const T* p) noexcept { return p; } // exposition only
The name ranges​::​cdata denotes a customization point object ([customization.point.object]).
Given a subexpression E with type T, let t be an lvalue that denotes the reified object for E.
  • If E is an rvalue and enable_borrowed_range<remove_cv_t<T>> is false, ranges​::​cdata(E) is ill-formed.
  • Otherwise, ranges​::​cdata(E) is expression-equivalent to as-const-pointer(ranges​::​data(possibly-const-range(t))).
[Note 1: 
Whenever ranges​::​cdata(E) is a valid expression, it has pointer to constant object type.
— end note]