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 tai_time<common_type_t<_Duration, seconds>>
20// from_utc(const utc<_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::from_utc(cr::utc_clock::from_sys(cr::sys_days{cr::January / 1 / 1958} - 10s)) ==
40 cr::tai_seconds{0s});
41
42 assert(cr::tai_clock::from_utc(cr::utc_clock::from_sys(cr::sys_days{cr::January / 1 / 2000})) ==
43 cr::tai_seconds{(cr::sys_days{cr::January / 1 / 2000} + unix_to_tai_epoch_offset).time_since_epoch()} + 32s);
44}
45
46template <class Duration>
47static void test_leap_seconds(std::chrono::utc_time<Duration> utc,
48 std::chrono::tai_time<Duration> expected,
49 std::source_location loc = std::source_location::current()) {
50 auto tai = std::chrono::tai_clock::from_utc(utc);
51 TEST_REQUIRE(tai == expected,
52 TEST_WRITE_CONCATENATED(loc, "\nExpected output ", expected, "\nActual output ", tai, '\n'));
53}
54
55// Tests set if existing database entries at the time of writing.
56static void test_transitions() {
57 using namespace std::literals::chrono_literals;
58 namespace cr = std::chrono;
59
60 // "sys" is the time of the transition to the next leap second.
61 // "elapsed" is the number of leap seconds before the transition.
62 auto test_transition = [](cr::sys_days sys, cr::seconds elapsed) {
63 constexpr auto unix_to_tai_epoch_offset =
64 cr::sys_days{cr::January / 1 / 1970} - cr::sys_days{cr::January / 1 / 1958};
65 cr::tai_seconds tai{sys.time_since_epoch() + unix_to_tai_epoch_offset + elapsed};
66
67 test_leap_seconds(cr::utc_clock::from_sys(sys - 1ns), tai - 1ns);
68 test_leap_seconds(cr::utc_clock::from_sys(sys), tai + 1s);
69 test_leap_seconds(cr::utc_clock::from_sys(sys) + 1ns, tai + 1s + 1ns);
70 };
71
72 // Transitions from the start of UTC.
73 test_transition(cr::sys_days{cr::July / 1 / 1972}, 10s);
74 test_transition(cr::sys_days{cr::January / 1 / 1973}, 11s);
75 test_transition(cr::sys_days{cr::January / 1 / 1974}, 12s);
76 test_transition(cr::sys_days{cr::January / 1 / 1975}, 13s);
77 test_transition(cr::sys_days{cr::January / 1 / 1976}, 14s);
78 test_transition(cr::sys_days{cr::January / 1 / 1977}, 15s);
79 test_transition(cr::sys_days{cr::January / 1 / 1978}, 16s);
80 test_transition(cr::sys_days{cr::January / 1 / 1979}, 17s);
81 test_transition(cr::sys_days{cr::January / 1 / 1980}, 18s);
82 test_transition(cr::sys_days{cr::July / 1 / 1981}, 19s);
83 test_transition(cr::sys_days{cr::July / 1 / 1982}, 20s);
84 test_transition(cr::sys_days{cr::July / 1 / 1983}, 21s);
85 test_transition(cr::sys_days{cr::July / 1 / 1985}, 22s);
86 test_transition(cr::sys_days{cr::January / 1 / 1988}, 23s);
87 test_transition(cr::sys_days{cr::January / 1 / 1990}, 24s);
88 test_transition(cr::sys_days{cr::January / 1 / 1991}, 25s);
89 test_transition(cr::sys_days{cr::July / 1 / 1992}, 26s);
90 test_transition(cr::sys_days{cr::July / 1 / 1993}, 27s);
91 test_transition(cr::sys_days{cr::July / 1 / 1994}, 28s);
92 test_transition(cr::sys_days{cr::January / 1 / 1996}, 29s);
93 test_transition(cr::sys_days{cr::July / 1 / 1997}, 30s);
94 test_transition(cr::sys_days{cr::January / 1 / 1999}, 31s);
95 test_transition(cr::sys_days{cr::January / 1 / 2006}, 32s);
96 test_transition(cr::sys_days{cr::January / 1 / 2009}, 33s);
97 test_transition(cr::sys_days{cr::July / 1 / 2012}, 34s);
98 test_transition(cr::sys_days{cr::July / 1 / 2015}, 35s);
99 test_transition(cr::sys_days{cr::January / 1 / 2017}, 36s);
100}
101
102// Tests whether the return type is the expected type.
103static void test_return_type() {
104 using namespace std::literals::chrono_literals;
105 namespace cr = std::chrono;
106
107 {
108 [[maybe_unused]] std::same_as<cr::tai_time<cr::nanoseconds>> decltype(auto) _ =
109 cr::tai_clock::from_utc(cr::utc_time<cr::nanoseconds>{0ns});
110 }
111 {
112 [[maybe_unused]] std::same_as<cr::tai_time<cr::microseconds>> decltype(auto) _ =
113 cr::tai_clock::from_utc(cr::utc_time<cr::microseconds>{0us});
114 }
115 {
116 [[maybe_unused]] std::same_as<cr::tai_time<cr::milliseconds>> decltype(auto) _ =
117 cr::tai_clock::from_utc(cr::utc_time<cr::milliseconds>{0ms});
118 }
119
120 {
121 [[maybe_unused]] std::same_as<cr::tai_time<cr::seconds>> decltype(auto) _ =
122 cr::tai_clock::from_utc(cr::utc_time<cr::seconds>{cr::seconds{0}});
123 }
124
125 {
126 [[maybe_unused]] std::same_as<cr::tai_time<cr::seconds>> decltype(auto) _ =
127 cr::tai_clock::from_utc(cr::utc_time<cr::minutes>{cr::minutes{0}});
128 }
129 {
130 [[maybe_unused]] std::same_as<cr::tai_time<cr::seconds>> decltype(auto) _ =
131 cr::tai_clock::from_utc(cr::utc_time<cr::hours>{cr::hours{0}});
132 }
133 {
134 [[maybe_unused]] std::same_as<cr::tai_time<cr::seconds>> decltype(auto) _ =
135 cr::tai_clock::from_utc(cr::utc_time<cr::days>{cr::days{0}});
136 }
137 {
138 [[maybe_unused]] std::same_as<cr::tai_time<cr::seconds>> decltype(auto) _ =
139 cr::tai_clock::from_utc(cr::utc_time<cr::weeks>{cr::weeks{0}});
140 }
141 {
142 [[maybe_unused]] std::same_as<cr::tai_time<cr::seconds>> decltype(auto) _ =
143 cr::tai_clock::from_utc(cr::utc_time<cr::months>{cr::months{0}});
144 }
145 {
146 [[maybe_unused]] std::same_as<cr::tai_time<cr::seconds>> decltype(auto) _ =
147 cr::tai_clock::from_utc(cr::utc_time<cr::years>{cr::years{0}});
148 }
149}
150
151int main(int, const char**) {
152 using namespace std::literals::chrono_literals;
153 std::chrono::utc_seconds time = std::chrono::utc_seconds{0s};
154 static_assert(noexcept(std::chrono::tai_clock::from_utc(time)));
155
156 test_known_values();
157 test_transitions();
158 test_return_type();
159
160 return 0;
161}
162

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