[libcxx-commits] [libcxx] [libc++][chrono] implements UTC clock. (PR #90393)

[Louis Dionne via libcxx-commits]

================
@@ -0,0 +1,220 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// UNSUPPORTED: no-filesystem, no-localization, no-tzdb
+
+// XFAIL: libcpp-has-no-incomplete-tzdb
+// XFAIL: availability-tzdb-missing
+
+// <chrono>
+
+// class utc_clock;
+
+// static sys_time<common_type_t<_Duration, seconds>>
+// to_sys(const utc_time<_Duration>& __time);
+
+#include <chrono>
+#include <cassert>
+
+#include "test_macros.h"
+#include "assert_macros.h"
+#include "concat_macros.h"
+
+template <class Duration>
+static void test_leap_seconds(std::chrono::utc_time<Duration> time, std::chrono::sys_time<Duration> expected) {
+  auto result = std::chrono::utc_clock::to_sys(time);
+  TEST_REQUIRE(
+      result == expected,
+      TEST_WRITE_CONCATENATED("\tTime: ", time, "\nExpected output ", expected, "\nActual output   ", result, '\n'));
+}
+
+static std::chrono::sys_seconds get_sys_time(long long seconds_since_1900) {
+  // The file leap-seconds.list stores dates since 1 January 1900, 00:00:00, we want
+  // seconds since 1 January 1970.
+  constexpr auto __offset =
----------------
ldionne wrote:

```suggestion
  constexpr auto offset =
```

https://github.com/llvm/llvm-project/pull/90393