[llvm-branch-commits] [libcxx] [libc++][chrono] Adds the sys_info class. (PR #85619)

[Louis Dionne via llvm-branch-commits]

================
@@ -0,0 +1,53 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+#ifndef _LIBCPP___CHRONO_SYS_INFO_H
+#define _LIBCPP___CHRONO_SYS_INFO_H
+
+#include <version>
+// Enable the contents of the header only when libc++ was built with experimental features enabled.
+#if !defined(_LIBCPP_HAS_NO_INCOMPLETE_TZDB)
+
+#  include <__chrono/duration.h>
+#  include <__chrono/system_clock.h>
+#  include <__chrono/time_point.h>
+#  include <__config>
+#  include <string>
+
+#  if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#    pragma GCC system_header
+#  endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#  if _LIBCPP_STD_VER >= 20 && !defined(_LIBCPP_HAS_NO_TIME_ZONE_DATABASE) && !defined(_LIBCPP_HAS_NO_FILESYSTEM) &&   \
+      !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+
+namespace chrono {
+
+struct sys_info {
----------------
ldionne wrote:

Do you have a test where you actually check that `sys_info` can be created as e.g.

```c++
sys_info info{a, b, c, d, e};
assert(info.begin == a);
// etc...
```

Also

```c++
sys_info info{.begin = a, etc..};
```

This is technically just an aggregate type so we should ensure that ours is one. Actually, I would replace the test `libcxx/test/std/time/time.zone/time.zone.info/time.zone.info.sys/sys_info.members.compile.pass.cpp` by this test.

https://github.com/llvm/llvm-project/pull/85619