[libc++][chrono] Loads tzdata.zi in tzdb. (#74928)

This implements the loading of the tzdata.zi file and store its contents
in the tzdb struct.

This adds all required members except:
- the leap seconds,
- the locate_zone, and
- current_zone.

The class time_zone is incomplete and only contains the parts needed for
storing the parsed data.

The class time_zone_link is fully implemented including its non-member
functions.

Implements parts of:
- P0355 Extending <chrono> to Calendars and Time Zones
- P1614 The Mothership has Landed

Implements:
- P1982 Rename link to time_zone_link

1 files changed, 32 insertions, 0 deletions

diff --git a/libcxx/src/time_zone.cpp b/libcxx/src/time_zone.cpp
new file mode 100644
index 0000000..b6bf06a
--- /dev/null
+++ b/libcxx/src/time_zone.cpp
@@ -0,0 +1,32 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// For information see https://libcxx.llvm.org/DesignDocs/TimeZone.html
+
+#include <chrono>
+
+#include "include/tzdb/time_zone_private.h"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace chrono {
+
+[[nodiscard]] _LIBCPP_EXPORTED_FROM_ABI time_zone time_zone::__create(unique_ptr<time_zone::__impl>&& __p) {
+  _LIBCPP_ASSERT_NON_NULL(__p != nullptr, "initialized time_zone without a valid pimpl object");
+  time_zone result;
+  result.__impl_ = std::move(__p);
+  return result;
+}
+
+_LIBCPP_EXPORTED_FROM_ABI time_zone::~time_zone() = default;
+
+[[nodiscard]] _LIBCPP_EXPORTED_FROM_ABI string_view time_zone::__name() const noexcept { return __impl_->__name(); }
+
+} // namespace chrono
+
+_LIBCPP_END_NAMESPACE_STD