1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9// REQUIRES: std-at-least-c++20
10// UNSUPPORTED: no-filesystem, no-localization, no-tzdb
11
12// XFAIL: libcpp-has-no-experimental-tzdb
13// XFAIL: availability-tzdb-missing
14
15// <chrono>
16//
17// class tai_clock;
18
19// static utc_time<common_type_t<_Duration, seconds>>
20// to_utc(const tai_time<_Duration>& __time) noexcept;
21
22#include <chrono>
23#include <cassert>
24#include <source_location>
25
26#include "test_macros.h"
27#include "assert_macros.h"
28#include "concat_macros.h"
29
30static void test_known_values() {
31 namespace cr = std::chrono;
32 using namespace std::literals::chrono_literals;
33 constexpr auto unix_to_tai_epoch_offset = cr::sys_days{cr::January / 1 / 1970} - cr::sys_days{cr::January / 1 / 1958};
34
35 // [time.clock.tai.overview]/1
36 // ... 1958-01-01 00:00:00 TAI is equivalent to 1957-12-31 23:59:50 UTC
37 // ... 2000-01-01 00:00:00 UTC is equivalent to 2000-01-01 00:00:32 TAI
38
39 assert(cr::tai_clock::to_utc(cr::tai_seconds{0s}) ==
40 cr::utc_clock::from_sys(cr::sys_days{cr::January / 1 / 1958} - 10s));
41
42 assert(cr::tai_clock::to_utc(
43 cr::tai_seconds{(cr::sys_days{cr::January / 1 / 2000} + unix_to_tai_epoch_offset).time_since_epoch()} +
44 32s) == cr::utc_clock::from_sys(cr::sys_days{cr::January / 1 / 2000}));
45}
46
47template <class Duration>
48static void test_leap_seconds(std::chrono::tai_time<Duration> tai,
49 std::chrono::utc_time<Duration> expected,
50 std::source_location loc = std::source_location::current()) {
51 auto utc = std::chrono::tai_clock::to_utc(tai);
52 TEST_REQUIRE(utc == expected,
53 TEST_WRITE_CONCATENATED(loc, "\nExpected output ", expected, "\nActual output ", utc, '\n'));
54}
55
56// Tests set if existing database entries at the time of writing.
57static void test_transitions() {
58 using namespace std::literals::chrono_literals;
59 namespace cr = std::chrono;
60
61 // "sys" is the time of the transition to the next leap second.
62 // "elapsed" is the number of leap seconds before the transition.
63 auto test_transition = [](cr::sys_days sys, cr::seconds elapsed) {
64 constexpr auto unix_to_tai_epoch_offset =
65 cr::sys_days{cr::January / 1 / 1970} - cr::sys_days{cr::January / 1 / 1958};
66 cr::tai_seconds tai{sys.time_since_epoch() + unix_to_tai_epoch_offset + elapsed};
67
68 test_leap_seconds(tai - 1ns, cr::utc_clock::from_sys(sys - 1ns));
69 test_leap_seconds(tai + 1s, cr::utc_clock::from_sys(sys));
70 test_leap_seconds(tai + 1s + 1ns, cr::utc_clock::from_sys(sys + 1ns));
71 };
72
73 // Transitions from the start of UTC.
74 test_transition(cr::sys_days{cr::July / 1 / 1972}, 10s);
75 test_transition(cr::sys_days{cr::January / 1 / 1973}, 11s);
76 test_transition(cr::sys_days{cr::January / 1 / 1974}, 12s);
77 test_transition(cr::sys_days{cr::January / 1 / 1975}, 13s);
78 test_transition(cr::sys_days{cr::January / 1 / 1976}, 14s);
79 test_transition(cr::sys_days{cr::January / 1 / 1977}, 15s);
80 test_transition(cr::sys_days{cr::January / 1 / 1978}, 16s);
81 test_transition(cr::sys_days{cr::January / 1 / 1979}, 17s);
82 test_transition(cr::sys_days{cr::January / 1 / 1980}, 18s);
83 test_transition(cr::sys_days{cr::July / 1 / 1981}, 19s);
84 test_transition(cr::sys_days{cr::July / 1 / 1982}, 20s);
85 test_transition(cr::sys_days{cr::July / 1 / 1983}, 21s);
86 test_transition(cr::sys_days{cr::July / 1 / 1985}, 22s);
87 test_transition(cr::sys_days{cr::January / 1 / 1988}, 23s);
88 test_transition(cr::sys_days{cr::January / 1 / 1990}, 24s);
89 test_transition(cr::sys_days{cr::January / 1 / 1991}, 25s);
90 test_transition(cr::sys_days{cr::July / 1 / 1992}, 26s);
91 test_transition(cr::sys_days{cr::July / 1 / 1993}, 27s);
92 test_transition(cr::sys_days{cr::July / 1 / 1994}, 28s);
93 test_transition(cr::sys_days{cr::January / 1 / 1996}, 29s);
94 test_transition(cr::sys_days{cr::July / 1 / 1997}, 30s);
95 test_transition(cr::sys_days{cr::January / 1 / 1999}, 31s);
96 test_transition(cr::sys_days{cr::January / 1 / 2006}, 32s);
97 test_transition(cr::sys_days{cr::January / 1 / 2009}, 33s);
98 test_transition(cr::sys_days{cr::July / 1 / 2012}, 34s);
99 test_transition(cr::sys_days{cr::July / 1 / 2015}, 35s);
100 test_transition(cr::sys_days{cr::January / 1 / 2017}, 36s);
101}
102
103// Tests whether the return type is the expected type.
104static void test_return_type() {
105 using namespace std::literals::chrono_literals;
106 namespace cr = std::chrono;
107
108 {
109 [[maybe_unused]] std::same_as<cr::utc_time<cr::nanoseconds>> decltype(auto) _ =
110 cr::tai_clock::to_utc(cr::tai_time<cr::nanoseconds>{0ns});
111 }
112 {
113 [[maybe_unused]] std::same_as<cr::utc_time<cr::microseconds>> decltype(auto) _ =
114 cr::tai_clock::to_utc(cr::tai_time<cr::microseconds>{0us});
115 }
116 {
117 [[maybe_unused]] std::same_as<cr::utc_time<cr::milliseconds>> decltype(auto) _ =
118 cr::tai_clock::to_utc(cr::tai_time<cr::milliseconds>{0ms});
119 }
120
121 {
122 [[maybe_unused]] std::same_as<cr::utc_time<cr::seconds>> decltype(auto) _ =
123 cr::tai_clock::to_utc(cr::tai_time<cr::seconds>{cr::seconds{0}});
124 }
125
126 {
127 [[maybe_unused]] std::same_as<cr::utc_time<cr::seconds>> decltype(auto) _ =
128 cr::tai_clock::to_utc(cr::tai_time<cr::minutes>{cr::minutes{0}});
129 }
130 {
131 [[maybe_unused]] std::same_as<cr::utc_time<cr::seconds>> decltype(auto) _ =
132 cr::tai_clock::to_utc(cr::tai_time<cr::hours>{cr::hours{0}});
133 }
134 {
135 [[maybe_unused]] std::same_as<cr::utc_time<cr::seconds>> decltype(auto) _ =
136 cr::tai_clock::to_utc(cr::tai_time<cr::days>{cr::days{0}});
137 }
138 {
139 [[maybe_unused]] std::same_as<cr::utc_time<cr::seconds>> decltype(auto) _ =
140 cr::tai_clock::to_utc(cr::tai_time<cr::weeks>{cr::weeks{0}});
141 }
142 {
143 [[maybe_unused]] std::same_as<cr::utc_time<cr::seconds>> decltype(auto) _ =
144 cr::tai_clock::to_utc(cr::tai_time<cr::months>{cr::months{0}});
145 }
146 {
147 [[maybe_unused]] std::same_as<cr::utc_time<cr::seconds>> decltype(auto) _ =
148 cr::tai_clock::to_utc(cr::tai_time<cr::years>{cr::years{0}});
149 }
150}
151
152int main(int, const char**) {
153 using namespace std::literals::chrono_literals;
154
155 std::chrono::tai_seconds time = std::chrono::tai_seconds{0s};
156 static_assert(noexcept(std::chrono::tai_clock::to_utc(time)));
157
158 test_known_values();
159 test_transitions();
160 test_return_type();
161
162 return 0;
163}
164

source code of libcxx/test/std/time/time.clock/time.clock.tai/time.clock.tai.members/to_utc.pass.cpp