25 Ranges library [ranges]

25.3 Range access [range.access]

25.3.5 ranges​::​cend [range.access.cend]

1
#
The name ranges​::​cend 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.
Then:
  • (1.1)
    If E is an rvalue and enable_borrowed_range<remove_cv_t<T>> is false, ranges​::​cend(E) is ill-formed.
  • (1.2)
    Otherwise, let U be ranges​::​end(possibly-const-range(t)).
    ranges​::​cend(E) is expression-equivalent to const_sentinel<decltype(U)>(U).
2
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[Note 1: 
Whenever ranges​::​cend(E) is a valid expression, the types S and I of the expressions ranges​::​cend(E) and ranges​::​cbegin(E) model sentinel_for<S, I>.
If S models input_iterator, then S also models constant-iterator.
— end note]