Annex D (normative) Compatibility features [depr]

D.18 Variant [depr.variant]

1
#
The header <variant> has the following additions: namespace std { template<class T> struct variant_size<volatile T>; template<class T> struct variant_size<const volatile T>; template<size_t I, class T> struct variant_alternative<I, volatile T>; template<size_t I, class T> struct variant_alternative<I, const volatile T>; }
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template<class T> struct variant_size<volatile T>; template<class T> struct variant_size<const volatile T>;
2
#
Let VS denote variant_size<T> of the cv-unqualified type T.
Then specializations of each of the two templates meet the Cpp17UnaryTypeTrait requirements with a base characteristic of integral_constant<size_t, VS​::​value>.
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template<size_t I, class T> struct variant_alternative<I, volatile T>; template<size_t I, class T> struct variant_alternative<I, const volatile T>;
3
#
Let VA denote variant_alternative<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:
  • (3.1)
    for the first specialization, add_volatile_t<VA​::​type>, and
  • (3.2)
    for the second specialization, add_cv_t<VA​::​type>.