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2817. std::hash for nullptr_t

Section: 22.10.19 [unord.hash] Status: Resolved Submitter: Marshall Clow Opened: 2016-11-10 Last modified: 2020-09-06

Priority: Not Prioritized

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Discussion:

In the list of types that the library provides std::hash specializations, there is an entry for hash<T*>, but none entry for hash<nullptr_t>.

[2016-11-13, Daniel provides wording]

[2016-11-28]

Resolved by P0513R0

Proposed resolution:

This wording is relative to N4606.

1. Change 22.10 [function.objects], header <functional> synopsis, as indicated:

   […]
   
   // Hash function specializations
   template <> struct hash<bool>;
   […]
   template <> struct hash<long double>;
   template <> struct hash<nullptr_t>;
   
   template<class T> struct hash<T*>;
   […]
   

2. Change 22.10.19 [unord.hash] before p2, as indicated:

   template <> struct hash<bool>;
   […]
   template <> struct hash<long double>;
   template <> struct hash<nullptr_t>;
   template<class T> struct hash<T*>;