[libc++][TZDB] Implements zoned_seconds typedef.

[mordante]

Implements parts of:

• P0355 Extending to chrono Calendars and Time Zones

[llvmbot]

@llvm/pr-subscribers-libcxx

Author: Mark de Wever (mordante)

Changes

Implements parts of:

• P0355 Extending to chrono Calendars and Time Zones

---

Full diff: https://github.com/llvm/llvm-project/pull/95141.diff

4 Files Affected:

• (modified) libcxx/include/__chrono/zoned_time.h (+2)
• (modified) libcxx/include/chrono (+2)
• (modified) libcxx/modules/std/chrono.inc (-2)
• (modified) libcxx/test/std/time/time.zone/time.zone.zonedtime/types.compile.pass.cpp (+5)

diff --git a/libcxx/include/__chrono/zoned_time.h b/libcxx/include/__chrono/zoned_time.h
index db5e67135d844..d9518ce0a8313 100644
--- a/libcxx/include/__chrono/zoned_time.h
+++ b/libcxx/include/__chrono/zoned_time.h
@@ -204,6 +204,8 @@ template <class _Duration, class _TimeZonePtrOrName, class TimeZonePtr2>
 zoned_time(_TimeZonePtrOrName&&, zoned_time<_Duration, TimeZonePtr2>, choose = choose::earliest)
     -> zoned_time<common_type_t<_Duration, seconds>, __time_zone_representation<_TimeZonePtrOrName>>;
 
+using zoned_seconds = zoned_time<seconds>;
+
 template <class _Duration1, class _Duration2, class _TimeZonePtr>
 _LIBCPP_HIDE_FROM_ABI bool
 operator==(const zoned_time<_Duration1, _TimeZonePtr>& __lhs, const zoned_time<_Duration2, _TimeZonePtr>& __rhs) {
diff --git a/libcxx/include/chrono b/libcxx/include/chrono
index df7ebf45bd907..9a6159cf2c4ab 100644
--- a/libcxx/include/chrono
+++ b/libcxx/include/chrono
@@ -793,6 +793,8 @@ template<class T> struct zoned_traits;
 template<class Duration, class TimeZonePtr = const time_zone*>                   // C++20
 class zoned_time;
 
+using zoned_seconds = zoned_time<seconds>;                                       // C++20
+
 template<class Duration1, class Duration2, class TimeZonePtr>                    // C++20
   bool operator==(const zoned_time<Duration1, TimeZonePtr>& x,
                   const zoned_time<Duration2, TimeZonePtr>& y);
diff --git a/libcxx/modules/std/chrono.inc b/libcxx/modules/std/chrono.inc
index 89fe7284eb694..3ba3c46150c9c 100644
--- a/libcxx/modules/std/chrono.inc
+++ b/libcxx/modules/std/chrono.inc
@@ -233,9 +233,7 @@ export namespace std {
     // [time.zone.zonedtime], class template zoned_time
     using std::chrono::zoned_time;
 
-#    if 0
     using std::chrono::zoned_seconds;
-#    endif // if 0
 
     // [time.zone.leap], leap second support
     using std::chrono::leap_second;
diff --git a/libcxx/test/std/time/time.zone/time.zone.zonedtime/types.compile.pass.cpp b/libcxx/test/std/time/time.zone/time.zone.zonedtime/types.compile.pass.cpp
index f2b198249e73d..91e37d0d02897 100644
--- a/libcxx/test/std/time/time.zone/time.zone.zonedtime/types.compile.pass.cpp
+++ b/libcxx/test/std/time/time.zone/time.zone.zonedtime/types.compile.pass.cpp
@@ -23,6 +23,8 @@
 //    zoned_time& operator=(const zoned_time&) = default;
 //
 //  };
+//
+// using zoned_seconds = zoned_time<seconds>;
 
 #include <chrono>
 #include <concepts>
@@ -57,3 +59,6 @@ static_assert(!std::is_copy_constructible_v<std::chrono::zoned_time< std::chrono
 static_assert(!std::is_move_constructible_v<std::chrono::zoned_time< std::chrono::days, std::unique_ptr<int>>>);
 static_assert(!std::is_copy_assignable_v<std::chrono::zoned_time< std::chrono::days, std::unique_ptr<int>>>);
 static_assert(!std::is_move_assignable_v<std::chrono::zoned_time< std::chrono::days, std::unique_ptr<int>>>);
+
+// using zoned_seconds = zoned_time<seconds>;
+static_assert(std::same_as<std::chrono::zoned_seconds, std::chrono::zoned_time<std::chrono::seconds>>);