25 Ranges library [ranges]

25.3 Range access [range.access]

The name ranges::data 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:

(2.1)
If E is an rvalue and enable_borrowed_range<remove_cv_t<T>> is false, ranges::data(E) is ill-formed.
(2.2)
Otherwise, if T is an array type ([dcl.array]) and remove_all_extents_t<T> is an incomplete type, ranges::data(E) is ill-formed with no diagnostic required.
(2.3)
Otherwise, if auto(t.data()) is a valid expression of pointer to object type, ranges::data(E) is expression-equivalent to auto(t.data()).
(2.4)
Otherwise, if ranges::begin(t) is a valid expression whose type models contiguous_iterator, ranges::data(E) is expression-equivalent to to_address(ranges::begin(t)).
(2.5)
Otherwise, ranges::data(E) is ill-formed.

[Note 1:

Diagnosable ill-formed cases above result in substitution failure when ranges::data(E) appears in the immediate context of a template instantiation.

— end note]

[Note 2:

Whenever ranges::data(E) is a valid expression, it has pointer to object type.

— end note]