Rename link to time_zone_link

Addresses DE 346

Contents

• Introduction
• Wording

Introduction

The LEWG in Belfast requested that I write a paper which provides wording for DE 346 as modified by the discussion in LEWG. The LEWG chose the name time_zone_link as a replacement for link, and specifically chose not to change the associated data member of tzdb links.

Wording

1. Modify the synopsis in [time.syn] as indicated:

   ...
   // 27.11.9, class time_zone_link
   class time_zone_link;
   
   bool operator==(const time_zone_link& x, const time_zone_link& y);
   strong_ordering operator<=>(const time_zone_link& x, const time_zone_link& y);
   ...
   

2. Modify the synopsis in [time.zone.db.tzdb] as indicated:

   namespace std::chrono {
     struct tzdb {
       string                 version;
       vector<time_zone>      zones;
       vector<time_zone_link> links;
       vector<leap>           leaps;
   
       const time_zone* locate_zone(string_view tz_name) const;
       const time_zone* current_zone() const;
     };
   }
   

3. Modify [time.zone.db.tzdb]/p2 as indicated:

   const time_zone* locate_zone(string_view tz_name) const;
   

   2 Returns: If a time_zone is found for which name() == tz_name, returns a pointer to that time_zone. Otherwise if a link is found for which tz_name == link.name(), then a pointer is returned to the time_zone for which zone.name() == link.target().
   

   • If a time_zone, tz, is found for which tz.name() == tz_name, a pointer to tz;

   • otherwise, if a time_zone_link, tz_l, is found for which tz_l.name() == tz_name, then a pointer to the time_zone, tz, for which tz.name() == tz_l.target().

   [Note: A time_zone_link specifies an alternative name for a time_zone. — end note]

4. Modify the title of [time.zone.link] as indicated:

   Class time_zone_link

5. Modify [time.zone.link.overview] as indicated:

   namespace std::chrono {
     class time_zone_link {
     public:
       time_zone_link(time_zone_link&&) = default;
       time_zone_link& operator=(time_zone_link&&) = default;
   
       // unspecified additional constructors
   
       string_view name()   const noexcept;
       string_view target() const noexcept;
     };
   }
   

   1 A time_zone_link specifies an alternative name for a time_zone. time_zone_links are constructed when the time zone database is initialized.

6. Modify [time.zone.link.members]/p2 as indicated:

   string_view target() const noexcept;
   

   2 Returns: The name of the time_zone for which this time_zone_link provides an alternative name.

7. Modify [time.zone.link.nonmembers] as indicated:

   bool operator==(const time_zone_link& x, const time_zone_link& y) noexcept;
   

   1 Returns: x.name() == y.name().

   strong_ordering operator<=>(const time_zone_link& x, const time_zone_link& y) noexcept;
   

   2 Returns: x.name() <=> y.name().