tmp/tmpua4o0epv/{from.md → to.md}
RENAMED
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#### Member types <a id="pointer.traits.types">[[pointer.traits.types]]</a>
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``` cpp
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using element_type = see below;
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```
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*Type:* `
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valid and denotes a type [[temp.deduct]]; otherwise, `T` if `Ptr` is a
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class template instantiation of the form `SomePointer<T, Args>`, where
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`Args` is zero or more type arguments; otherwise, the specialization is
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ill-formed.
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``` cpp
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using difference_type = see below;
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```
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#### Member types <a id="pointer.traits.types">[[pointer.traits.types]]</a>
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The definitions in this subclause make use of the following
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exposition-only class template and concept:
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``` cpp
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template<class T>
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struct ptr-traits-elem // exposition only
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{ };
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template<class T> requires requires { typename T::element_type; }
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struct ptr-traits-elem<T>
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{ using type = typename T::element_type; };
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template<template<class...> class SomePointer, class T, class... Args>
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requires (!requires { typename SomePointer<T, Args...>::element_type; })
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struct ptr-traits-elem<SomePointer<T, Args...>>
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{ using type = T; };
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template<class Ptr>
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concept has-elem-type = // exposition only
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requires { typename ptr-traits-elem<Ptr>::type; }
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```
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If `Ptr` satisfies `has-elem-type`, a specialization
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`pointer_traits<Ptr>` generated from the `pointer_traits` primary
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template has the following members as well as those described in
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[[pointer.traits.functions]]; otherwise, such a specialization has no
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members by any of those names.
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``` cpp
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using pointer = see below;
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```
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*Type:* `Ptr`.
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``` cpp
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using element_type = see below;
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```
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*Type:* `typename `*`ptr-traits-elem`*`<Ptr>::type`.
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``` cpp
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using difference_type = see below;
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```
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