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> is false, ranges::data(E) is ill-formed.
(2.2)

Otherwise, if T is an array type ([dcl.array]) and remove_all_extents_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.

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[Note 2:

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

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