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 // UNSUPPORTED: c++03, c++11, c++14, c++17
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 time_zone;
18
19 // template <class _Duration>
20 // sys_time<common_type_t<Duration, seconds>>
21 // to_sys(const local_time<Duration>& tp, choose z) const;
22
23 #include <chrono>
24 #include <format>
25 #include <cassert>
26 #include <string_view>
27
28 #include "test_macros.h"
29
30 // Tests unique conversions. To make sure the test is does not depend on changes
31 // in the database it uses a time zone with a fixed offset.
test_unique()32 static void test_unique() {
33 using namespace std::literals::chrono_literals;
34
35 const std::chrono::time_zone* tz = std::chrono::locate_zone("Etc/GMT+1");
36
37 assert(tz->to_sys(std::chrono::local_time<std::chrono::nanoseconds>{-1ns}, std::chrono::choose::earliest) ==
38 std::chrono::sys_time<std::chrono::nanoseconds>{-1ns + 1h});
39
40 assert(tz->to_sys(std::chrono::local_time<std::chrono::microseconds>{0us}, std::chrono::choose::latest) ==
41 std::chrono::sys_time<std::chrono::microseconds>{1h});
42
43 assert(tz->to_sys(
44 std::chrono::local_time<std::chrono::seconds>{
45 (std::chrono::sys_days{std::chrono::January / 1 / -21970}).time_since_epoch()},
46 std::chrono::choose::earliest) ==
47 std::chrono::sys_time<std::chrono::seconds>{
48 (std::chrono::sys_days{std::chrono::January / 1 / -21970}).time_since_epoch() + 1h});
49
50 // sys_time<common_type_t<Duration, seconds>> is seconds for the larger types
51 assert(tz->to_sys(
52 std::chrono::local_time<std::chrono::days>{
53 (std::chrono::sys_days{std::chrono::January / 1 / 21970}).time_since_epoch()},
54 std::chrono::choose::latest) ==
55 std::chrono::sys_time<std::chrono::seconds>{
56 (std::chrono::sys_days{std::chrono::January / 1 / 21970}).time_since_epoch() + 1h});
57
58 assert(tz->to_sys(std::chrono::local_time<std::chrono::weeks>{}, std::chrono::choose::earliest) ==
59 std::chrono::sys_time<std::chrono::seconds>{
60 (std::chrono::sys_days{std::chrono::January / 1 / 1970}).time_since_epoch() + 1h});
61
62 // Note months and years cannot be streamed; however these functions don't
63 // throw an exception and thus can be used.
64 assert(tz->to_sys(std::chrono::local_time<std::chrono::months>{}, std::chrono::choose::latest) ==
65 std::chrono::sys_time<std::chrono::seconds>{
66 (std::chrono::sys_days{std::chrono::January / 1 / 1970}).time_since_epoch() + 1h});
67
68 assert(tz->to_sys(std::chrono::local_time<std::chrono::years>{}, std::chrono::choose::earliest) ==
69 std::chrono::sys_time<std::chrono::seconds>{
70 (std::chrono::sys_days{std::chrono::January / 1 / 1970}).time_since_epoch() + 1h});
71 }
72
73 // Tests non-existant conversions.
test_nonexistent()74 static void test_nonexistent() {
75 using namespace std::literals::chrono_literals;
76
77 const std::chrono::time_zone* tz = std::chrono::locate_zone("Europe/Berlin");
78
79 // Z Europe/Berlin 0:53:28 - LMT 1893 Ap
80 // ...
81 // 1 DE CE%sT 1980
82 // 1 E CE%sT
83 //
84 // ...
85 // R E 1981 ma - Mar lastSu 1u 1 S
86 // R E 1996 ma - O lastSu 1u 0 -
87
88 // Pick an historic date where it's well known what the time zone rules were.
89 // This makes it unlikely updates to the database change these rules.
90 std::chrono::local_time<std::chrono::seconds> time{
91 (std::chrono::sys_days{std::chrono::March / 30 / 1986} + 2h + 30min).time_since_epoch()};
92
93 std::chrono::sys_seconds expected{time.time_since_epoch() - 1h};
94
95 // Validates whether the database did not change.
96 std::chrono::local_info info = tz->get_info(time);
97 assert(info.result == std::chrono::local_info::nonexistent);
98
99 assert(tz->to_sys(time + 0ns, std::chrono::choose::earliest) == expected);
100 assert(tz->to_sys(time + 0us, std::chrono::choose::latest) == expected);
101 assert(tz->to_sys(time + 0ms, std::chrono::choose::earliest) == expected);
102 assert(tz->to_sys(time + 0s, std::chrono::choose::latest) == expected);
103 }
104
105 // Tests ambiguous conversions.
test_ambiguous()106 static void test_ambiguous() {
107 using namespace std::literals::chrono_literals;
108
109 const std::chrono::time_zone* tz = std::chrono::locate_zone("Europe/Berlin");
110
111 // Z Europe/Berlin 0:53:28 - LMT 1893 Ap
112 // ...
113 // 1 DE CE%sT 1980
114 // 1 E CE%sT
115 //
116 // ...
117 // R E 1981 ma - Mar lastSu 1u 1 S
118 // R E 1996 ma - O lastSu 1u 0 -
119
120 // Pick an historic date where it's well known what the time zone rules were.
121 // This makes it unlikely updates to the database change these rules.
122 std::chrono::local_time<std::chrono::seconds> time{
123 (std::chrono::sys_days{std::chrono::September / 28 / 1986} + 2h + 30min).time_since_epoch()};
124
125 std::chrono::sys_seconds earlier{time.time_since_epoch() - 2h};
126 std::chrono::sys_seconds later{time.time_since_epoch() - 1h};
127
128 // Validates whether the database did not change.
129 std::chrono::local_info info = tz->get_info(time);
130 assert(info.result == std::chrono::local_info::ambiguous);
131
132 assert(tz->to_sys(time + 0ns, std::chrono::choose::earliest) == earlier);
133 assert(tz->to_sys(time + 0us, std::chrono::choose::latest) == later);
134 assert(tz->to_sys(time + 0ms, std::chrono::choose::earliest) == earlier);
135 assert(tz->to_sys(time + 0s, std::chrono::choose::latest) == later);
136 }
137
138 // This test does the basic validations of this function. The library function
139 // uses `local_info get_info(const local_time<Duration>& tp)` as implementation
140 // detail. The get_info function does extensive testing of the data.
main(int,char **)141 int main(int, char**) {
142 test_unique();
143 test_nonexistent();
144 test_ambiguous();
145
146 return 0;
147 }
148