[llvm-branch-commits] [libcxx] [libc++][TZDB] Implements time_zone::to_sys. (PR #90901)
Mark de Wever via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Fri May 3 08:08:44 PDT 2024
https://github.com/mordante updated https://github.com/llvm/llvm-project/pull/90901
>From 775f5459258db3416e90dbe0f8b0ee24f7125e95 Mon Sep 17 00:00:00 2001
From: Mark de Wever <koraq at xs4all.nl>
Date: Wed, 17 Apr 2024 21:00:22 +0200
Subject: [PATCH] [libc++][TZDB] Implements time_zone::to_sys.
This implements the overload with the choose argument and adds this enum.
Implements parts of:
- P0355 Extending chrono to Calendars and Time Zones
---
libcxx/include/__chrono/time_zone.h | 32 ++++
libcxx/include/chrono | 4 +
libcxx/modules/std/chrono.inc | 3 -
.../diagnostics/chrono.nodiscard.verify.cpp | 3 +
.../time.zone.timezone/choose.pass.cpp | 37 +++++
.../assert.to_sys_choose.pass.cpp | 41 +++++
.../time.zone.members/to_sys_choose.pass.cpp | 147 ++++++++++++++++++
7 files changed, 264 insertions(+), 3 deletions(-)
create mode 100644 libcxx/test/libcxx/time/time.zone/time.zone.timezone/choose.pass.cpp
create mode 100644 libcxx/test/libcxx/time/time.zone/time.zone.timezone/time.zone.members/assert.to_sys_choose.pass.cpp
create mode 100644 libcxx/test/std/time/time.zone/time.zone.timezone/time.zone.members/to_sys_choose.pass.cpp
diff --git a/libcxx/include/__chrono/time_zone.h b/libcxx/include/__chrono/time_zone.h
index b7ce4ea659a1af..a18c5d5295b7d6 100644
--- a/libcxx/include/__chrono/time_zone.h
+++ b/libcxx/include/__chrono/time_zone.h
@@ -42,6 +42,8 @@ _LIBCPP_BEGIN_NAMESPACE_STD
namespace chrono {
+enum class choose { earliest, latest };
+
class _LIBCPP_AVAILABILITY_TZDB time_zone {
_LIBCPP_HIDE_FROM_ABI time_zone() = default;
@@ -96,6 +98,36 @@ class _LIBCPP_AVAILABILITY_TZDB time_zone {
return {};
}
+ template <class _Duration>
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI sys_time<common_type_t<_Duration, seconds>>
+ to_sys(const local_time<_Duration>& __time, choose __z) const {
+ local_info __info = get_info(__time);
+ switch (__info.result) {
+ case local_info::unique:
+ case local_info::nonexistent: // first and second are the same
+ return sys_time<common_type_t<_Duration, seconds>>{__time.time_since_epoch() - __info.first.offset};
+
+ case local_info::ambiguous:
+ switch (__z) {
+ case choose::earliest:
+ return sys_time<common_type_t<_Duration, seconds>>{__time.time_since_epoch() - __info.first.offset};
+
+ case choose::latest:
+ return sys_time<common_type_t<_Duration, seconds>>{__time.time_since_epoch() - __info.second.offset};
+
+ // Note a value out of bounds is not specified.
+ }
+ }
+
+ // TODO TZDB The standard does not specify anything in these cases.
+ _LIBCPP_ASSERT_ARGUMENT_WITHIN_DOMAIN(
+ __info.result != -1, "cannot convert the local time; it would be before the minimum system clock value");
+ _LIBCPP_ASSERT_ARGUMENT_WITHIN_DOMAIN(
+ __info.result != -2, "cannot convert the local time; it would be after the maximum system clock value");
+
+ return {};
+ }
+
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI const __impl& __implementation() const noexcept { return *__impl_; }
private:
diff --git a/libcxx/include/chrono b/libcxx/include/chrono
index 4b0ea938710bdd..c70b241f086464 100644
--- a/libcxx/include/chrono
+++ b/libcxx/include/chrono
@@ -774,6 +774,10 @@ class time_zone {
template<class Duration>
sys_time<common_type_t<Duration, seconds>>
to_sys(const local_time<Duration>& tp) const;
+
+ template<class Duration>
+ sys_time<common_type_t<Duration, seconds>>
+ to_sys(const local_time<Duration>& tp, choose z) const;
};
bool operator==(const time_zone& x, const time_zone& y) noexcept; // C++20
strong_ordering operator<=>(const time_zone& x, const time_zone& y) noexcept; // C++20
diff --git a/libcxx/modules/std/chrono.inc b/libcxx/modules/std/chrono.inc
index 38e3c4184521b7..9e16f09bd31afb 100644
--- a/libcxx/modules/std/chrono.inc
+++ b/libcxx/modules/std/chrono.inc
@@ -216,11 +216,8 @@ export namespace std {
using std::chrono::local_info;
using std::chrono::sys_info;
-# if 0
// [time.zone.timezone], class time_zone
using std::chrono::choose;
-# endif // if 0
-
using std::chrono::time_zone;
# if 0
diff --git a/libcxx/test/libcxx/diagnostics/chrono.nodiscard.verify.cpp b/libcxx/test/libcxx/diagnostics/chrono.nodiscard.verify.cpp
index fea1e4417cc12c..cba7916ff2c646 100644
--- a/libcxx/test/libcxx/diagnostics/chrono.nodiscard.verify.cpp
+++ b/libcxx/test/libcxx/diagnostics/chrono.nodiscard.verify.cpp
@@ -49,9 +49,12 @@ void test() {
{
std::chrono::sys_seconds s{};
std::chrono::local_seconds l{};
+ std::chrono::choose z = std::chrono::choose::earliest;
tz.name(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
tz.get_info(s); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
tz.get_info(l); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ tz.to_sys(l); // not nodiscard
+ tz.to_sys(l, z); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
operator==(tz, tz); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
operator<=>(tz, tz); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
}
diff --git a/libcxx/test/libcxx/time/time.zone/time.zone.timezone/choose.pass.cpp b/libcxx/test/libcxx/time/time.zone/time.zone.timezone/choose.pass.cpp
new file mode 100644
index 00000000000000..24424b0a2e2b0d
--- /dev/null
+++ b/libcxx/test/libcxx/time/time.zone/time.zone.timezone/choose.pass.cpp
@@ -0,0 +1,37 @@
+//===----------------------------------------------------------------------===//
+//
+// 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-experimental-tzdb
+// XFAIL: availability-tzdb-missing
+
+// <chrono>
+
+// enaum class choose;
+
+#include <chrono>
+#include <type_traits>
+#include <cassert>
+
+#include "test_macros.h"
+
+int main(int, char**) {
+ using E = std::chrono::choose;
+ static_assert(std::is_enum_v<E>);
+
+ // Check that E is a scoped enum by checking for conversions.
+ using UT = std::underlying_type_t<E>;
+ static_assert(!std::is_convertible_v<E, UT>);
+
+ [[maybe_unused]] const E& early = E::earliest;
+ [[maybe_unused]] const E& late = E::latest;
+
+ return 0;
+}
diff --git a/libcxx/test/libcxx/time/time.zone/time.zone.timezone/time.zone.members/assert.to_sys_choose.pass.cpp b/libcxx/test/libcxx/time/time.zone/time.zone.timezone/time.zone.members/assert.to_sys_choose.pass.cpp
new file mode 100644
index 00000000000000..65429345ae794f
--- /dev/null
+++ b/libcxx/test/libcxx/time/time.zone/time.zone.timezone/time.zone.members/assert.to_sys_choose.pass.cpp
@@ -0,0 +1,41 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// REQUIRES: has-unix-headers
+// REQUIRES: libcpp-hardening-mode={{extensive|debug}}
+// XFAIL: libcpp-hardening-mode=debug && availability-verbose_abort-missing
+
+// XFAIL: libcpp-has-no-experimental-tzdb
+
+// <chrono>
+
+// template <class _Duration>
+// sys_time<common_type_t<Duration, seconds>>
+// to_sys(const local_time<Duration>& tp, choose z) const;
+
+#include <chrono>
+
+#include "check_assertion.h"
+
+// Tests values that cannot be converted. To make sure the test is does not depend on changes
+// in the database it uses a time zone with a fixed offset.
+int main(int, char**) {
+ TEST_LIBCPP_ASSERT_FAILURE(
+ std::chrono::locate_zone("Etc/GMT-1")->to_sys(std::chrono::local_seconds::min(), std::chrono::choose::earliest),
+ "cannot convert the local time; it would be before the minimum system clock value");
+
+ // TODO TZDB look why std::chrono::local_seconds::max() fails
+ TEST_LIBCPP_ASSERT_FAILURE(
+ std::chrono::locate_zone("Etc/GMT+1")
+ ->to_sys(std::chrono::local_seconds::max() - std::chrono::seconds(1), std::chrono::choose::latest),
+ "cannot convert the local time; it would be after the maximum system clock value");
+
+ return 0;
+}
diff --git a/libcxx/test/std/time/time.zone/time.zone.timezone/time.zone.members/to_sys_choose.pass.cpp b/libcxx/test/std/time/time.zone/time.zone.timezone/time.zone.members/to_sys_choose.pass.cpp
new file mode 100644
index 00000000000000..bad4ef352e9b91
--- /dev/null
+++ b/libcxx/test/std/time/time.zone/time.zone.timezone/time.zone.members/to_sys_choose.pass.cpp
@@ -0,0 +1,147 @@
+//===----------------------------------------------------------------------===//
+//
+// 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-experimental-tzdb
+// XFAIL: availability-tzdb-missing
+
+// <chrono>
+
+// class time_zone;
+
+// template <class _Duration>
+// sys_time<common_type_t<Duration, seconds>>
+// to_sys(const local_time<Duration>& tp, choose z) const;
+
+#include <chrono>
+#include <format>
+#include <cassert>
+#include <string_view>
+
+#include "test_macros.h"
+
+// Tests unique conversions. To make sure the test is does not depend on changes
+// in the database it uses a time zone with a fixed offset.
+static void test_unique() {
+ using namespace std::literals::chrono_literals;
+
+ const std::chrono::time_zone* tz = std::chrono::locate_zone("Etc/GMT+1");
+
+ assert(tz->to_sys(std::chrono::local_time<std::chrono::nanoseconds>{-1ns}, std::chrono::choose::earliest) ==
+ std::chrono::sys_time<std::chrono::nanoseconds>{-1ns + 1h});
+
+ assert(tz->to_sys(std::chrono::local_time<std::chrono::microseconds>{0us}, std::chrono::choose::latest) ==
+ std::chrono::sys_time<std::chrono::microseconds>{1h});
+
+ assert(tz->to_sys(
+ std::chrono::local_time<std::chrono::seconds>{
+ (std::chrono::sys_days{std::chrono::January / 1 / -21970}).time_since_epoch()},
+ std::chrono::choose::earliest) ==
+ std::chrono::sys_time<std::chrono::seconds>{
+ (std::chrono::sys_days{std::chrono::January / 1 / -21970}).time_since_epoch() + 1h});
+
+ // sys_time<common_type_t<Duration, seconds>> is seconds for the larger types
+ assert(tz->to_sys(
+ std::chrono::local_time<std::chrono::days>{
+ (std::chrono::sys_days{std::chrono::January / 1 / 21970}).time_since_epoch()},
+ std::chrono::choose::latest) ==
+ std::chrono::sys_time<std::chrono::seconds>{
+ (std::chrono::sys_days{std::chrono::January / 1 / 21970}).time_since_epoch() + 1h});
+
+ assert(tz->to_sys(std::chrono::local_time<std::chrono::weeks>{}, std::chrono::choose::earliest) ==
+ std::chrono::sys_time<std::chrono::seconds>{
+ (std::chrono::sys_days{std::chrono::January / 1 / 1970}).time_since_epoch() + 1h});
+
+ // Note months and years cannot be streamed; however these functions don't
+ // throw an exception and thus can be used.
+ assert(tz->to_sys(std::chrono::local_time<std::chrono::months>{}, std::chrono::choose::latest) ==
+ std::chrono::sys_time<std::chrono::seconds>{
+ (std::chrono::sys_days{std::chrono::January / 1 / 1970}).time_since_epoch() + 1h});
+
+ assert(tz->to_sys(std::chrono::local_time<std::chrono::years>{}, std::chrono::choose::earliest) ==
+ std::chrono::sys_time<std::chrono::seconds>{
+ (std::chrono::sys_days{std::chrono::January / 1 / 1970}).time_since_epoch() + 1h});
+}
+
+// Tests non-existant conversions.
+static void test_nonexistent() {
+ using namespace std::literals::chrono_literals;
+
+ const std::chrono::time_zone* tz = std::chrono::locate_zone("Europe/Berlin");
+
+ // Z Europe/Berlin 0:53:28 - LMT 1893 Ap
+ // ...
+ // 1 DE CE%sT 1980
+ // 1 E CE%sT
+ //
+ // ...
+ // R E 1981 ma - Mar lastSu 1u 1 S
+ // R E 1996 ma - O lastSu 1u 0 -
+
+ // Pick an historic date where it's well known what the time zone rules were.
+ // This makes it unlikely updates to the database change these rules.
+ std::chrono::local_time<std::chrono::seconds> time{
+ (std::chrono::sys_days{std::chrono::March / 30 / 1986} + 2h + 30min).time_since_epoch()};
+
+ std::chrono::sys_seconds expected{time.time_since_epoch() - 1h};
+
+ // Validates whether the database did not change.
+ std::chrono::local_info info = tz->get_info(time);
+ assert(info.result == std::chrono::local_info::nonexistent);
+
+ assert(tz->to_sys(time + 0ns, std::chrono::choose::earliest) == expected);
+ assert(tz->to_sys(time + 0us, std::chrono::choose::latest) == expected);
+ assert(tz->to_sys(time + 0ms, std::chrono::choose::earliest) == expected);
+ assert(tz->to_sys(time + 0s, std::chrono::choose::latest) == expected);
+}
+
+// Tests ambiguous conversions.
+static void test_ambiguous() {
+ using namespace std::literals::chrono_literals;
+
+ const std::chrono::time_zone* tz = std::chrono::locate_zone("Europe/Berlin");
+
+ // Z Europe/Berlin 0:53:28 - LMT 1893 Ap
+ // ...
+ // 1 DE CE%sT 1980
+ // 1 E CE%sT
+ //
+ // ...
+ // R E 1981 ma - Mar lastSu 1u 1 S
+ // R E 1996 ma - O lastSu 1u 0 -
+
+ // Pick an historic date where it's well known what the time zone rules were.
+ // This makes it unlikely updates to the database change these rules.
+ std::chrono::local_time<std::chrono::seconds> time{
+ (std::chrono::sys_days{std::chrono::September / 28 / 1986} + 2h + 30min).time_since_epoch()};
+
+ std::chrono::sys_seconds earlier{time.time_since_epoch() - 2h};
+ std::chrono::sys_seconds later{time.time_since_epoch() - 1h};
+
+ // Validates whether the database did not change.
+ std::chrono::local_info info = tz->get_info(time);
+ assert(info.result == std::chrono::local_info::ambiguous);
+
+ assert(tz->to_sys(time + 0ns, std::chrono::choose::earliest) == earlier);
+ assert(tz->to_sys(time + 0us, std::chrono::choose::latest) == later);
+ assert(tz->to_sys(time + 0ms, std::chrono::choose::earliest) == earlier);
+ assert(tz->to_sys(time + 0s, std::chrono::choose::latest) == later);
+}
+
+// This test does the basic validations of this function. The library function
+// uses `local_info get_info(const local_time<Duration>& tp)` as implementation
+// detail. The get_info function does extensive testing of the data.
+int main(int, char**) {
+ test_unique();
+ test_nonexistent();
+ test_ambiguous();
+
+ return 0;
+}
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