Annex D (normative) Compatibility features [depr]

D.20 Tuple [depr.tuple]

1
#
The header <tuple> has the following additions: namespace std { template<class T> struct tuple_size<volatile T>; template<class T> struct tuple_size<const volatile T>; template<size_t I, class T> struct tuple_element<I, volatile T>; template<size_t I, class T> struct tuple_element<I, const volatile T>; }
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template<class T> struct tuple_size<volatile T>; template<class T> struct tuple_size<const volatile T>;
2
#
Let TS denote tuple_size<T> of the cv-unqualified type T.
If the expression TS​::​value is well-formed when treated as an unevaluated operand, then specializations of each of the two templates meet the Cpp17TransformationTrait requirements with a base characteristic of integral_constant<size_t, TS​::​value>.
Otherwise, they have no member value.
3
#
Access checking is performed as if in a context unrelated to TS and T.
Only the validity of the immediate context of the expression is considered.
4
#
In addition to being available via inclusion of the <tuple> header, the two templates are available when any of the headers <array>, <ranges>, or <utility> are included.
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template<size_t I, class T> struct tuple_element<I, volatile T>; template<size_t I, class T> struct tuple_element<I, const volatile T>;
5
#
Let TE denote tuple_element_t<I, T> of the cv-unqualified type T.
Then specializations of each of the two templates meet the Cpp17TransformationTrait requirements with a member typedef type that names the following type:
  • (5.1)
    for the first specialization, add_volatile_t<TE>, and
  • (5.2)
    for the second specialization, add_cv_t<TE>.
6
#
In addition to being available via inclusion of the <tuple> header, the two templates are available when any of the headers <array>, <ranges>, or <utility> are included.