- fd5f3d7077270ffc5ea74cdb9e18bbae3b9b46aa Fix typo optional -> variant by Abseil Team <absl-team@google.com>

  - 9136c06dfa8dbfdde0a427ad3509e34763d607a6 Fix string_view_test and str_cat_test build under MSVC de... by Derek Mauro <dmauro@google.com>
  - a463820f9441888f4368aa87328599e3209f9b07 Removes constexpr optional<T>::operator->(). This was don... by Abseil Team <absl-team@google.com>
  - 3bf78a7f126daafff329f7815d507422f1ca378d Remove dependencies on external CCTZ project. by Shaindel Schwartz <shaindel@google.com>
  - a4ae574a11b1ddf6e88459af3d638cf79aea7ecd Internal change by Jon Cohen <cohenjon@google.com>

GitOrigin-RevId: fd5f3d7077270ffc5ea74cdb9e18bbae3b9b46aa
Change-Id: I6ab8ab99863716fe9b2745a12ef285f7a6da6d1e

1 files changed, 1259 insertions, 0 deletions

diff --git a/absl/time/internal/cctz/src/time_zone_lookup_test.cc b/absl/time/internal/cctz/src/time_zone_lookup_test.cc
new file mode 100644
index 000000000000..a5d73d5492e2
--- /dev/null
+++ b/absl/time/internal/cctz/src/time_zone_lookup_test.cc
@@ -0,0 +1,1259 @@
+// Copyright 2016 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+//   Unless required by applicable law or agreed to in writing, software
+//   distributed under the License is distributed on an "AS IS" BASIS,
+//   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//   See the License for the specific language governing permissions and
+//   limitations under the License.
+
+#include "absl/time/internal/cctz/include/cctz/time_zone.h"
+
+#include <chrono>
+#include <cstddef>
+#include <future>
+#include <string>
+#include <thread>
+#include <vector>
+
+#include "absl/time/internal/cctz/include/cctz/civil_time.h"
+#include "gtest/gtest.h"
+
+using std::chrono::time_point_cast;
+using std::chrono::system_clock;
+using std::chrono::nanoseconds;
+using std::chrono::microseconds;
+using std::chrono::milliseconds;
+using std::chrono::seconds;
+using std::chrono::minutes;
+using std::chrono::hours;
+
+namespace absl {
+namespace time_internal {
+namespace cctz {
+
+namespace {
+
+// A list of known time-zone names.
+const char* const kTimeZoneNames[] = {
+  "Africa/Abidjan",
+  "Africa/Accra",
+  "Africa/Addis_Ababa",
+  "Africa/Algiers",
+  "Africa/Asmara",
+  "Africa/Asmera",
+  "Africa/Bamako",
+  "Africa/Bangui",
+  "Africa/Banjul",
+  "Africa/Bissau",
+  "Africa/Blantyre",
+  "Africa/Brazzaville",
+  "Africa/Bujumbura",
+  "Africa/Cairo",
+  "Africa/Casablanca",
+  "Africa/Ceuta",
+  "Africa/Conakry",
+  "Africa/Dakar",
+  "Africa/Dar_es_Salaam",
+  "Africa/Djibouti",
+  "Africa/Douala",
+  "Africa/El_Aaiun",
+  "Africa/Freetown",
+  "Africa/Gaborone",
+  "Africa/Harare",
+  "Africa/Johannesburg",
+  "Africa/Juba",
+  "Africa/Kampala",
+  "Africa/Khartoum",
+  "Africa/Kigali",
+  "Africa/Kinshasa",
+  "Africa/Lagos",
+  "Africa/Libreville",
+  "Africa/Lome",
+  "Africa/Luanda",
+  "Africa/Lubumbashi",
+  "Africa/Lusaka",
+  "Africa/Malabo",
+  "Africa/Maputo",
+  "Africa/Maseru",
+  "Africa/Mbabane",
+  "Africa/Mogadishu",
+  "Africa/Monrovia",
+  "Africa/Nairobi",
+  "Africa/Ndjamena",
+  "Africa/Niamey",
+  "Africa/Nouakchott",
+  "Africa/Ouagadougou",
+  "Africa/Porto-Novo",
+  "Africa/Sao_Tome",
+  "Africa/Timbuktu",
+  "Africa/Tripoli",
+  "Africa/Tunis",
+  "Africa/Windhoek",
+  "America/Adak",
+  "America/Anchorage",
+  "America/Anguilla",
+  "America/Antigua",
+  "America/Araguaina",
+  "America/Argentina/Buenos_Aires",
+  "America/Argentina/Catamarca",
+  "America/Argentina/ComodRivadavia",
+  "America/Argentina/Cordoba",
+  "America/Argentina/Jujuy",
+  "America/Argentina/La_Rioja",
+  "America/Argentina/Mendoza",
+  "America/Argentina/Rio_Gallegos",
+  "America/Argentina/Salta",
+  "America/Argentina/San_Juan",
+  "America/Argentina/San_Luis",
+  "America/Argentina/Tucuman",
+  "America/Argentina/Ushuaia",
+  "America/Aruba",
+  "America/Asuncion",
+  "America/Atikokan",
+  "America/Atka",
+  "America/Bahia",
+  "America/Bahia_Banderas",
+  "America/Barbados",
+  "America/Belem",
+  "America/Belize",
+  "America/Blanc-Sablon",
+  "America/Boa_Vista",
+  "America/Bogota",
+  "America/Boise",
+  "America/Buenos_Aires",
+  "America/Cambridge_Bay",
+  "America/Campo_Grande",
+  "America/Cancun",
+  "America/Caracas",
+  "America/Catamarca",
+  "America/Cayenne",
+  "America/Cayman",
+  "America/Chicago",
+  "America/Chihuahua",
+  "America/Coral_Harbour",
+  "America/Cordoba",
+  "America/Costa_Rica",
+  "America/Creston",
+  "America/Cuiaba",
+  "America/Curacao",
+  "America/Danmarkshavn",
+  "America/Dawson",
+  "America/Dawson_Creek",
+  "America/Denver",
+  "America/Detroit",
+  "America/Dominica",
+  "America/Edmonton",
+  "America/Eirunepe",
+  "America/El_Salvador",
+  "America/Ensenada",
+  "America/Fort_Nelson",
+  "America/Fort_Wayne",
+  "America/Fortaleza",
+  "America/Glace_Bay",
+  "America/Godthab",
+  "America/Goose_Bay",
+  "America/Grand_Turk",
+  "America/Grenada",
+  "America/Guadeloupe",
+  "America/Guatemala",
+  "America/Guayaquil",
+  "America/Guyana",
+  "America/Halifax",
+  "America/Havana",
+  "America/Hermosillo",
+  "America/Indiana/Indianapolis",
+  "America/Indiana/Knox",
+  "America/Indiana/Marengo",
+  "America/Indiana/Petersburg",
+  "America/Indiana/Tell_City",
+  "America/Indiana/Vevay",
+  "America/Indiana/Vincennes",
+  "America/Indiana/Winamac",
+  "America/Indianapolis",
+  "America/Inuvik",
+  "America/Iqaluit",
+  "America/Jamaica",
+  "America/Jujuy",
+  "America/Juneau",
+  "America/Kentucky/Louisville",
+  "America/Kentucky/Monticello",
+  "America/Knox_IN",
+  "America/Kralendijk",
+  "America/La_Paz",
+  "America/Lima",
+  "America/Los_Angeles",
+  "America/Louisville",
+  "America/Lower_Princes",
+  "America/Maceio",
+  "America/Managua",
+  "America/Manaus",
+  "America/Marigot",
+  "America/Martinique",
+  "America/Matamoros",
+  "America/Mazatlan",
+  "America/Mendoza",
+  "America/Menominee",
+  "America/Merida",
+  "America/Metlakatla",
+  "America/Mexico_City",
+  "America/Miquelon",
+  "America/Moncton",
+  "America/Monterrey",
+  "America/Montevideo",
+  "America/Montreal",
+  "America/Montserrat",
+  "America/Nassau",
+  "America/New_York",
+  "America/Nipigon",
+  "America/Nome",
+  "America/Noronha",
+  "America/North_Dakota/Beulah",
+  "America/North_Dakota/Center",
+  "America/North_Dakota/New_Salem",
+  "America/Ojinaga",
+  "America/Panama",
+  "America/Pangnirtung",
+  "America/Paramaribo",
+  "America/Phoenix",
+  "America/Port-au-Prince",
+  "America/Port_of_Spain",
+  "America/Porto_Acre",
+  "America/Porto_Velho",
+  "America/Puerto_Rico",
+  "America/Punta_Arenas",
+  "America/Rainy_River",
+  "America/Rankin_Inlet",
+  "America/Recife",
+  "America/Regina",
+  "America/Resolute",
+  "America/Rio_Branco",
+  "America/Rosario",
+  "America/Santa_Isabel",
+  "America/Santarem",
+  "America/Santiago",
+  "America/Santo_Domingo",
+  "America/Sao_Paulo",
+  "America/Scoresbysund",
+  "America/Shiprock",
+  "America/Sitka",
+  "America/St_Barthelemy",
+  "America/St_Johns",
+  "America/St_Kitts",
+  "America/St_Lucia",
+  "America/St_Thomas",
+  "America/St_Vincent",
+  "America/Swift_Current",
+  "America/Tegucigalpa",
+  "America/Thule",
+  "America/Thunder_Bay",
+  "America/Tijuana",
+  "America/Toronto",
+  "America/Tortola",
+  "America/Vancouver",
+  "America/Virgin",
+  "America/Whitehorse",
+  "America/Winnipeg",
+  "America/Yakutat",
+  "America/Yellowknife",
+  "Antarctica/Casey",
+  "Antarctica/Davis",
+  "Antarctica/DumontDUrville",
+  "Antarctica/Macquarie",
+  "Antarctica/Mawson",
+  "Antarctica/McMurdo",
+  "Antarctica/Palmer",
+  "Antarctica/Rothera",
+  "Antarctica/South_Pole",
+  "Antarctica/Syowa",
+  "Antarctica/Troll",
+  "Antarctica/Vostok",
+  "Arctic/Longyearbyen",
+  "Asia/Aden",
+  "Asia/Almaty",
+  "Asia/Amman",
+  "Asia/Anadyr",
+  "Asia/Aqtau",
+  "Asia/Aqtobe",
+  "Asia/Ashgabat",
+  "Asia/Ashkhabad",
+  "Asia/Atyrau",
+  "Asia/Baghdad",
+  "Asia/Bahrain",
+  "Asia/Baku",
+  "Asia/Bangkok",
+  "Asia/Barnaul",
+  "Asia/Beirut",
+  "Asia/Bishkek",
+  "Asia/Brunei",
+  "Asia/Calcutta",
+  "Asia/Chita",
+  "Asia/Choibalsan",
+  "Asia/Chongqing",
+  "Asia/Chungking",
+  "Asia/Colombo",
+  "Asia/Dacca",
+  "Asia/Damascus",
+  "Asia/Dhaka",
+  "Asia/Dili",
+  "Asia/Dubai",
+  "Asia/Dushanbe",
+  "Asia/Famagusta",
+  "Asia/Gaza",
+  "Asia/Harbin",
+  "Asia/Hebron",
+  "Asia/Ho_Chi_Minh",
+  "Asia/Hong_Kong",
+  "Asia/Hovd",
+  "Asia/Irkutsk",
+  "Asia/Istanbul",
+  "Asia/Jakarta",
+  "Asia/Jayapura",
+  "Asia/Jerusalem",
+  "Asia/Kabul",
+  "Asia/Kamchatka",
+  "Asia/Karachi",
+  "Asia/Kashgar",
+  "Asia/Kathmandu",
+  "Asia/Katmandu",
+  "Asia/Khandyga",
+  "Asia/Kolkata",
+  "Asia/Krasnoyarsk",
+  "Asia/Kuala_Lumpur",
+  "Asia/Kuching",
+  "Asia/Kuwait",
+  "Asia/Macao",
+  "Asia/Macau",
+  "Asia/Magadan",
+  "Asia/Makassar",
+  "Asia/Manila",
+  "Asia/Muscat",
+  "Asia/Nicosia",
+  "Asia/Novokuznetsk",
+  "Asia/Novosibirsk",
+  "Asia/Omsk",
+  "Asia/Oral",
+  "Asia/Phnom_Penh",
+  "Asia/Pontianak",
+  "Asia/Pyongyang",
+  "Asia/Qatar",
+  "Asia/Qyzylorda",
+  "Asia/Rangoon",
+  "Asia/Riyadh",
+  "Asia/Saigon",
+  "Asia/Sakhalin",
+  "Asia/Samarkand",
+  "Asia/Seoul",
+  "Asia/Shanghai",
+  "Asia/Singapore",
+  "Asia/Srednekolymsk",
+  "Asia/Taipei",
+  "Asia/Tashkent",
+  "Asia/Tbilisi",
+  "Asia/Tehran",
+  "Asia/Tel_Aviv",
+  "Asia/Thimbu",
+  "Asia/Thimphu",
+  "Asia/Tokyo",
+  "Asia/Tomsk",
+  "Asia/Ujung_Pandang",
+  "Asia/Ulaanbaatar",
+  "Asia/Ulan_Bator",
+  "Asia/Urumqi",
+  "Asia/Ust-Nera",
+  "Asia/Vientiane",
+  "Asia/Vladivostok",
+  "Asia/Yakutsk",
+  "Asia/Yangon",
+  "Asia/Yekaterinburg",
+  "Asia/Yerevan",
+  "Atlantic/Azores",
+  "Atlantic/Bermuda",
+  "Atlantic/Canary",
+  "Atlantic/Cape_Verde",
+  "Atlantic/Faeroe",
+  "Atlantic/Faroe",
+  "Atlantic/Jan_Mayen",
+  "Atlantic/Madeira",
+  "Atlantic/Reykjavik",
+  "Atlantic/South_Georgia",
+  "Atlantic/St_Helena",
+  "Atlantic/Stanley",
+  "Australia/ACT",
+  "Australia/Adelaide",
+  "Australia/Brisbane",
+  "Australia/Broken_Hill",
+  "Australia/Canberra",
+  "Australia/Currie",
+  "Australia/Darwin",
+  "Australia/Eucla",
+  "Australia/Hobart",
+  "Australia/LHI",
+  "Australia/Lindeman",
+  "Australia/Lord_Howe",
+  "Australia/Melbourne",
+  "Australia/NSW",
+  "Australia/North",
+  "Australia/Perth",
+  "Australia/Queensland",
+  "Australia/South",
+  "Australia/Sydney",
+  "Australia/Tasmania",
+  "Australia/Victoria",
+  "Australia/West",
+  "Australia/Yancowinna",
+  "Brazil/Acre",
+  "Brazil/DeNoronha",
+  "Brazil/East",
+  "Brazil/West",
+  "CET",
+  "CST6CDT",
+  "Canada/Atlantic",
+  "Canada/Central",
+  "Canada/East-Saskatchewan",
+  "Canada/Eastern",
+  "Canada/Mountain",
+  "Canada/Newfoundland",
+  "Canada/Pacific",
+  "Canada/Saskatchewan",
+  "Canada/Yukon",
+  "Chile/Continental",
+  "Chile/EasterIsland",
+  "Cuba",
+  "EET",
+  "EST",
+  "EST5EDT",
+  "Egypt",
+  "Eire",
+  "Etc/GMT",
+  "Etc/GMT+0",
+  "Etc/GMT+1",
+  "Etc/GMT+10",
+  "Etc/GMT+11",
+  "Etc/GMT+12",
+  "Etc/GMT+2",
+  "Etc/GMT+3",
+  "Etc/GMT+4",
+  "Etc/GMT+5",
+  "Etc/GMT+6",
+  "Etc/GMT+7",
+  "Etc/GMT+8",
+  "Etc/GMT+9",
+  "Etc/GMT-0",
+  "Etc/GMT-1",
+  "Etc/GMT-10",
+  "Etc/GMT-11",
+  "Etc/GMT-12",
+  "Etc/GMT-13",
+  "Etc/GMT-14",
+  "Etc/GMT-2",
+  "Etc/GMT-3",
+  "Etc/GMT-4",
+  "Etc/GMT-5",
+  "Etc/GMT-6",
+  "Etc/GMT-7",
+  "Etc/GMT-8",
+  "Etc/GMT-9",
+  "Etc/GMT0",
+  "Etc/Greenwich",
+  "Etc/UCT",
+  "Etc/UTC",
+  "Etc/Universal",
+  "Etc/Zulu",
+  "Europe/Amsterdam",
+  "Europe/Andorra",
+  "Europe/Astrakhan",
+  "Europe/Athens",
+  "Europe/Belfast",
+  "Europe/Belgrade",
+  "Europe/Berlin",
+  "Europe/Bratislava",
+  "Europe/Brussels",
+  "Europe/Bucharest",
+  "Europe/Budapest",
+  "Europe/Busingen",
+  "Europe/Chisinau",
+  "Europe/Copenhagen",
+  "Europe/Dublin",
+  "Europe/Gibraltar",
+  "Europe/Guernsey",
+  "Europe/Helsinki",
+  "Europe/Isle_of_Man",
+  "Europe/Istanbul",
+  "Europe/Jersey",
+  "Europe/Kaliningrad",
+  "Europe/Kiev",
+  "Europe/Kirov",
+  "Europe/Lisbon",
+  "Europe/Ljubljana",
+  "Europe/London",
+  "Europe/Luxembourg",
+  "Europe/Madrid",
+  "Europe/Malta",
+  "Europe/Mariehamn",
+  "Europe/Minsk",
+  "Europe/Monaco",
+  "Europe/Moscow",
+  "Europe/Nicosia",
+  "Europe/Oslo",
+  "Europe/Paris",
+  "Europe/Podgorica",
+  "Europe/Prague",
+  "Europe/Riga",
+  "Europe/Rome",
+  "Europe/Samara",
+  "Europe/San_Marino",
+  "Europe/Sarajevo",
+  "Europe/Saratov",
+  "Europe/Simferopol",
+  "Europe/Skopje",
+  "Europe/Sofia",
+  "Europe/Stockholm",
+  "Europe/Tallinn",
+  "Europe/Tirane",
+  "Europe/Tiraspol",
+  "Europe/Ulyanovsk",
+  "Europe/Uzhgorod",
+  "Europe/Vaduz",
+  "Europe/Vatican",
+  "Europe/Vienna",
+  "Europe/Vilnius",
+  "Europe/Volgograd",
+  "Europe/Warsaw",
+  "Europe/Zagreb",
+  "Europe/Zaporozhye",
+  "Europe/Zurich",
+  "GB",
+  "GB-Eire",
+  "GMT",
+  "GMT+0",
+  "GMT-0",
+  "GMT0",
+  "Greenwich",
+  "HST",
+  "Hongkong",
+  "Iceland",
+  "Indian/Antananarivo",
+  "Indian/Chagos",
+  "Indian/Christmas",
+  "Indian/Cocos",
+  "Indian/Comoro",
+  "Indian/Kerguelen",
+  "Indian/Mahe",
+  "Indian/Maldives",
+  "Indian/Mauritius",
+  "Indian/Mayotte",
+  "Indian/Reunion",
+  "Iran",
+  "Israel",
+  "Jamaica",
+  "Japan",
+  "Kwajalein",
+  "Libya",
+  "MET",
+  "MST",
+  "MST7MDT",
+  "Mexico/BajaNorte",
+  "Mexico/BajaSur",
+  "Mexico/General",
+  "NZ",
+  "NZ-CHAT",
+  "Navajo",
+  "PRC",
+  "PST8PDT",
+  "Pacific/Apia",
+  "Pacific/Auckland",
+  "Pacific/Bougainville",
+  "Pacific/Chatham",
+  "Pacific/Chuuk",
+  "Pacific/Easter",
+  "Pacific/Efate",
+  "Pacific/Enderbury",
+  "Pacific/Fakaofo",
+  "Pacific/Fiji",
+  "Pacific/Funafuti",
+  "Pacific/Galapagos",
+  "Pacific/Gambier",
+  "Pacific/Guadalcanal",
+  "Pacific/Guam",
+  "Pacific/Honolulu",
+  "Pacific/Johnston",
+  "Pacific/Kiritimati",
+  "Pacific/Kosrae",
+  "Pacific/Kwajalein",
+  "Pacific/Majuro",
+  "Pacific/Marquesas",
+  "Pacific/Midway",
+  "Pacific/Nauru",
+  "Pacific/Niue",
+  "Pacific/Norfolk",
+  "Pacific/Noumea",
+  "Pacific/Pago_Pago",
+  "Pacific/Palau",
+  "Pacific/Pitcairn",
+  "Pacific/Pohnpei",
+  "Pacific/Ponape",
+  "Pacific/Port_Moresby",
+  "Pacific/Rarotonga",
+  "Pacific/Saipan",
+  "Pacific/Samoa",
+  "Pacific/Tahiti",
+  "Pacific/Tarawa",
+  "Pacific/Tongatapu",
+  "Pacific/Truk",
+  "Pacific/Wake",
+  "Pacific/Wallis",
+  "Pacific/Yap",
+  "Poland",
+  "Portugal",
+  "ROC",
+  "ROK",
+  "Singapore",
+  "Turkey",
+  "UCT",
+  "US/Alaska",
+  "US/Aleutian",
+  "US/Arizona",
+  "US/Central",
+  "US/East-Indiana",
+  "US/Eastern",
+  "US/Hawaii",
+  "US/Indiana-Starke",
+  "US/Michigan",
+  "US/Mountain",
+  "US/Pacific",
+  "US/Samoa",
+  "UTC",
+  "Universal",
+  "W-SU",
+  "WET",
+  "Zulu",
+  nullptr
+};
+
+// Helper to return a loaded time zone by value (UTC on error).
+time_zone LoadZone(const std::string& name) {
+  time_zone tz;
+  load_time_zone(name, &tz);
+  return tz;
+}
+
+// This helper is a macro so that failed expectations show up with the
+// correct line numbers.
+#define ExpectTime(tp, tz, y, m, d, hh, mm, ss, off, isdst, zone) \
+  do {                                                            \
+    time_zone::absolute_lookup al = tz.lookup(tp);                \
+    EXPECT_EQ(y, al.cs.year());                                   \
+    EXPECT_EQ(m, al.cs.month());                                  \
+    EXPECT_EQ(d, al.cs.day());                                    \
+    EXPECT_EQ(hh, al.cs.hour());                                  \
+    EXPECT_EQ(mm, al.cs.minute());                                \
+    EXPECT_EQ(ss, al.cs.second());                                \
+    EXPECT_EQ(off, al.offset);                                    \
+    EXPECT_TRUE(isdst == al.is_dst);                              \
+    /* EXPECT_STREQ(zone, al.abbr); */                            \
+  } while (0)
+
+}  // namespace
+
+TEST(TimeZones, LoadZonesConcurrently) {
+  std::promise<void> ready_promise;
+  std::shared_future<void> ready_future(ready_promise.get_future());
+  auto load_zones = [ready_future](std::promise<void>* started,
+                                   std::set<std::string>* failures) {
+    started->set_value();
+    ready_future.wait();
+    for (const char* const* np = kTimeZoneNames; *np != nullptr; ++np) {
+      std::string zone = *np;
+      time_zone tz;
+      if (load_time_zone(zone, &tz)) {
+        EXPECT_EQ(zone, tz.name());
+      } else {
+        failures->insert(zone);
+      }
+    }
+  };
+
+  const std::size_t n_threads = 128;
+  std::vector<std::thread> threads;
+  std::vector<std::set<std::string>> thread_failures(n_threads);
+  for (std::size_t i = 0; i != n_threads; ++i) {
+    std::promise<void> started;
+    threads.emplace_back(load_zones, &started, &thread_failures[i]);
+    started.get_future().wait();
+  }
+  ready_promise.set_value();
+  for (auto& thread : threads) {
+    thread.join();
+  }
+
+  // Allow a small number of failures to account for skew between
+  // the contents of kTimeZoneNames and the zoneinfo data source.
+  const std::size_t max_failures = 3;
+  std::set<std::string> failures;
+  for (const auto& thread_failure : thread_failures) {
+    failures.insert(thread_failure.begin(), thread_failure.end());
+  }
+  EXPECT_LE(failures.size(), max_failures) << testing::PrintToString(failures);
+}
+
+TEST(TimeZone, NamedTimeZones) {
+  const time_zone utc = utc_time_zone();
+  EXPECT_EQ("UTC", utc.name());
+  const time_zone nyc = LoadZone("America/New_York");
+  EXPECT_EQ("America/New_York", nyc.name());
+  const time_zone syd = LoadZone("Australia/Sydney");
+  EXPECT_EQ("Australia/Sydney", syd.name());
+  const time_zone fixed0 = fixed_time_zone(sys_seconds::zero());
+  EXPECT_EQ("UTC", fixed0.name());
+  const time_zone fixed_pos =
+      fixed_time_zone(hours(3) + minutes(25) + seconds(45));
+  EXPECT_EQ("Fixed/UTC+03:25:45", fixed_pos.name());
+  const time_zone fixed_neg =
+      fixed_time_zone(-(hours(12) + minutes(34) + seconds(56)));
+  EXPECT_EQ("Fixed/UTC-12:34:56", fixed_neg.name());
+}
+
+TEST(TimeZone, Failures) {
+  time_zone tz;
+  EXPECT_FALSE(load_time_zone(":America/Los_Angeles", &tz));
+
+  tz = LoadZone("America/Los_Angeles");
+  EXPECT_FALSE(load_time_zone("Invalid/TimeZone", &tz));
+  EXPECT_EQ(system_clock::from_time_t(0),
+            convert(civil_second(1970, 1, 1, 0, 0, 0), tz));  // UTC
+
+  // Ensures that the load still fails on a subsequent attempt.
+  tz = LoadZone("America/Los_Angeles");
+  EXPECT_FALSE(load_time_zone("Invalid/TimeZone", &tz));
+  EXPECT_EQ(system_clock::from_time_t(0),
+            convert(civil_second(1970, 1, 1, 0, 0, 0), tz));  // UTC
+
+  // Loading an empty std::string timezone should fail.
+  tz = LoadZone("America/Los_Angeles");
+  EXPECT_FALSE(load_time_zone("", &tz));
+  EXPECT_EQ(system_clock::from_time_t(0),
+            convert(civil_second(1970, 1, 1, 0, 0, 0), tz));  // UTC
+}
+
+TEST(TimeZone, Equality) {
+  const time_zone a;
+  const time_zone b;
+  EXPECT_EQ(a, b);
+  EXPECT_EQ(a.name(), b.name());
+
+  const time_zone implicit_utc;
+  const time_zone explicit_utc = utc_time_zone();
+  EXPECT_EQ(implicit_utc, explicit_utc);
+  EXPECT_EQ(implicit_utc.name(), explicit_utc.name());
+
+  const time_zone fixed_zero = fixed_time_zone(sys_seconds::zero());
+  EXPECT_EQ(fixed_zero, LoadZone(fixed_zero.name()));
+  EXPECT_EQ(fixed_zero, explicit_utc);
+
+  const time_zone fixed_utc = LoadZone("Fixed/UTC+00:00:00");
+  EXPECT_EQ(fixed_utc, LoadZone(fixed_utc.name()));
+  EXPECT_EQ(fixed_utc, explicit_utc);
+
+  const time_zone fixed_pos =
+      fixed_time_zone(hours(3) + minutes(25) + seconds(45));
+  EXPECT_EQ(fixed_pos, LoadZone(fixed_pos.name()));
+  EXPECT_NE(fixed_pos, explicit_utc);
+  const time_zone fixed_neg =
+      fixed_time_zone(-(hours(12) + minutes(34) + seconds(56)));
+  EXPECT_EQ(fixed_neg, LoadZone(fixed_neg.name()));
+  EXPECT_NE(fixed_neg, explicit_utc);
+
+  const time_zone fixed_lim = fixed_time_zone(hours(24));
+  EXPECT_EQ(fixed_lim, LoadZone(fixed_lim.name()));
+  EXPECT_NE(fixed_lim, explicit_utc);
+  const time_zone fixed_ovfl = fixed_time_zone(hours(24) + seconds(1));
+  EXPECT_EQ(fixed_ovfl, LoadZone(fixed_ovfl.name()));
+  EXPECT_EQ(fixed_ovfl, explicit_utc);
+
+  EXPECT_EQ(fixed_time_zone(seconds(1)), fixed_time_zone(seconds(1)));
+
+  const time_zone local = local_time_zone();
+  EXPECT_EQ(local, LoadZone(local.name()));
+
+  time_zone la = LoadZone("America/Los_Angeles");
+  time_zone nyc = LoadZone("America/New_York");
+  EXPECT_NE(la, nyc);
+}
+
+TEST(StdChronoTimePoint, TimeTAlignment) {
+  // Ensures that the Unix epoch and the system clock epoch are an integral
+  // number of seconds apart. This simplifies conversions to/from time_t.
+  auto diff = system_clock::time_point() - system_clock::from_time_t(0);
+  EXPECT_EQ(system_clock::time_point::duration::zero(), diff % seconds(1));
+}
+
+TEST(BreakTime, TimePointResolution) {
+  const time_zone utc = utc_time_zone();
+  const auto t0 = system_clock::from_time_t(0);
+
+  ExpectTime(time_point_cast<nanoseconds>(t0), utc,
+             1970, 1, 1, 0, 0, 0, 0, false, "UTC");
+  ExpectTime(time_point_cast<microseconds>(t0), utc,
+             1970, 1, 1, 0, 0, 0, 0, false, "UTC");
+  ExpectTime(time_point_cast<milliseconds>(t0), utc,
+             1970, 1, 1, 0, 0, 0, 0, false, "UTC");
+  ExpectTime(time_point_cast<seconds>(t0), utc,
+             1970, 1, 1, 0, 0, 0, 0, false, "UTC");
+  ExpectTime(time_point_cast<sys_seconds>(t0), utc,
+             1970, 1, 1, 0, 0, 0, 0, false, "UTC");
+  ExpectTime(time_point_cast<minutes>(t0), utc,
+             1970, 1, 1, 0, 0, 0, 0, false, "UTC");
+  ExpectTime(time_point_cast<hours>(t0), utc,
+             1970, 1, 1, 0, 0, 0, 0, false, "UTC");
+}
+
+TEST(BreakTime, LocalTimeInUTC) {
+  const time_zone tz = utc_time_zone();
+  const auto tp = system_clock::from_time_t(0);
+  ExpectTime(tp, tz, 1970, 1, 1, 0, 0, 0, 0, false, "UTC");
+  EXPECT_EQ(weekday::thursday, get_weekday(civil_day(convert(tp, tz))));
+}
+
+TEST(BreakTime, LocalTimeInUTCUnaligned) {
+  const time_zone tz = utc_time_zone();
+  const auto tp = system_clock::from_time_t(0) - milliseconds(500);
+  ExpectTime(tp, tz, 1969, 12, 31, 23, 59, 59, 0, false, "UTC");
+  EXPECT_EQ(weekday::wednesday, get_weekday(civil_day(convert(tp, tz))));
+}
+
+TEST(BreakTime, LocalTimePosix) {
+  // See IEEE Std 1003.1-1988 B.2.3 General Terms, Epoch.
+  const time_zone tz = utc_time_zone();
+  const auto tp = system_clock::from_time_t(536457599);
+  ExpectTime(tp, tz, 1986, 12, 31, 23, 59, 59, 0, false, "UTC");
+  EXPECT_EQ(weekday::wednesday, get_weekday(civil_day(convert(tp, tz))));
+}
+
+TEST(TimeZoneImpl, LocalTimeInFixed) {
+  const sys_seconds offset = -(hours(8) + minutes(33) + seconds(47));
+  const time_zone tz = fixed_time_zone(offset);
+  const auto tp = system_clock::from_time_t(0);
+  ExpectTime(tp, tz, 1969, 12, 31, 15, 26, 13, offset.count(), false,
+             "UTC-083347");
+  EXPECT_EQ(weekday::wednesday, get_weekday(civil_day(convert(tp, tz))));
+}
+
+TEST(BreakTime, LocalTimeInNewYork) {
+  const time_zone tz = LoadZone("America/New_York");
+  const auto tp = system_clock::from_time_t(45);
+  ExpectTime(tp, tz, 1969, 12, 31, 19, 0, 45, -5 * 60 * 60, false, "EST");
+  EXPECT_EQ(weekday::wednesday, get_weekday(civil_day(convert(tp, tz))));
+}
+
+TEST(BreakTime, LocalTimeInMTV) {
+  const time_zone tz = LoadZone("America/Los_Angeles");
+  const auto tp = system_clock::from_time_t(1380855729);
+  ExpectTime(tp, tz, 2013, 10, 3, 20, 2, 9, -7 * 60 * 60, true, "PDT");
+  EXPECT_EQ(weekday::thursday, get_weekday(civil_day(convert(tp, tz))));
+}
+
+TEST(BreakTime, LocalTimeInSydney) {
+  const time_zone tz = LoadZone("Australia/Sydney");
+  const auto tp = system_clock::from_time_t(90);
+  ExpectTime(tp, tz, 1970, 1, 1, 10, 1, 30, 10 * 60 * 60, false, "AEST");
+  EXPECT_EQ(weekday::thursday, get_weekday(civil_day(convert(tp, tz))));
+}
+
+TEST(MakeTime, TimePointResolution) {
+  const time_zone utc = utc_time_zone();
+  const time_point<nanoseconds> tp_ns =
+      convert(civil_second(2015, 1, 2, 3, 4, 5), utc);
+  EXPECT_EQ("04:05", format("%M:%E*S", tp_ns, utc));
+  const time_point<microseconds> tp_us =
+      convert(civil_second(2015, 1, 2, 3, 4, 5), utc);
+  EXPECT_EQ("04:05", format("%M:%E*S", tp_us, utc));
+  const time_point<milliseconds> tp_ms =
+      convert(civil_second(2015, 1, 2, 3, 4, 5), utc);
+  EXPECT_EQ("04:05", format("%M:%E*S", tp_ms, utc));
+  const time_point<seconds> tp_s =
+      convert(civil_second(2015, 1, 2, 3, 4, 5), utc);
+  EXPECT_EQ("04:05", format("%M:%E*S", tp_s, utc));
+  const time_point<sys_seconds> tp_s64 =
+      convert(civil_second(2015, 1, 2, 3, 4, 5), utc);
+  EXPECT_EQ("04:05", format("%M:%E*S", tp_s64, utc));
+
+  // These next two require time_point_cast because the conversion from a
+  // resolution of seconds (the return value of convert()) to a coarser
+  // resolution requires an explicit cast.
+  const time_point<minutes> tp_m =
+      time_point_cast<minutes>(
+          convert(civil_second(2015, 1, 2, 3, 4, 5), utc));
+  EXPECT_EQ("04:00", format("%M:%E*S", tp_m, utc));
+  const time_point<hours> tp_h =
+      time_point_cast<hours>(
+          convert(civil_second(2015, 1, 2, 3, 4, 5), utc));
+  EXPECT_EQ("00:00", format("%M:%E*S", tp_h, utc));
+}
+
+TEST(MakeTime, Normalization) {
+  const time_zone tz = LoadZone("America/New_York");
+  const auto tp = convert(civil_second(2009, 2, 13, 18, 31, 30), tz);
+  EXPECT_EQ(system_clock::from_time_t(1234567890), tp);
+
+  // Now requests for the same time_point but with out-of-range fields.
+  EXPECT_EQ(tp, convert(civil_second(2008, 14, 13, 18, 31, 30), tz));  // month
+  EXPECT_EQ(tp, convert(civil_second(2009, 1, 44, 18, 31, 30), tz));   // day
+  EXPECT_EQ(tp, convert(civil_second(2009, 2, 12, 42, 31, 30), tz));   // hour
+  EXPECT_EQ(tp, convert(civil_second(2009, 2, 13, 17, 91, 30), tz));   // minute
+  EXPECT_EQ(tp, convert(civil_second(2009, 2, 13, 18, 30, 90), tz));   // second
+}
+
+// NOTE: Run this with --copt=-ftrapv to detect overflow problems.
+TEST(MakeTime, SysSecondsLimits) {
+  const char RFC3339[] =  "%Y-%m-%dT%H:%M:%S%Ez";
+  const time_zone utc = utc_time_zone();
+  const time_zone east = fixed_time_zone(hours(14));
+  const time_zone west = fixed_time_zone(-hours(14));
+  time_point<sys_seconds> tp;
+
+  // Approach the maximal time_point<sys_seconds> value from below.
+  tp = convert(civil_second(292277026596, 12, 4, 15, 30, 6), utc);
+  EXPECT_EQ("292277026596-12-04T15:30:06+00:00", format(RFC3339, tp, utc));
+  tp = convert(civil_second(292277026596, 12, 4, 15, 30, 7), utc);
+  EXPECT_EQ("292277026596-12-04T15:30:07+00:00", format(RFC3339, tp, utc));
+  EXPECT_EQ(time_point<sys_seconds>::max(), tp);
+  tp = convert(civil_second(292277026596, 12, 4, 15, 30, 8), utc);
+  EXPECT_EQ(time_point<sys_seconds>::max(), tp);
+  tp = convert(civil_second::max(), utc);
+  EXPECT_EQ(time_point<sys_seconds>::max(), tp);
+
+  // Checks that we can also get the maximal value for a far-east zone.
+  tp = convert(civil_second(292277026596, 12, 5, 5, 30, 7), east);
+  EXPECT_EQ("292277026596-12-05T05:30:07+14:00", format(RFC3339, tp, east));
+  EXPECT_EQ(time_point<sys_seconds>::max(), tp);
+  tp = convert(civil_second(292277026596, 12, 5, 5, 30, 8), east);
+  EXPECT_EQ(time_point<sys_seconds>::max(), tp);
+  tp = convert(civil_second::max(), east);
+  EXPECT_EQ(time_point<sys_seconds>::max(), tp);
+
+  // Checks that we can also get the maximal value for a far-west zone.
+  tp = convert(civil_second(292277026596, 12, 4, 1, 30, 7), west);
+  EXPECT_EQ("292277026596-12-04T01:30:07-14:00", format(RFC3339, tp, west));
+  EXPECT_EQ(time_point<sys_seconds>::max(), tp);
+  tp = convert(civil_second(292277026596, 12, 4, 7, 30, 8), west);
+  EXPECT_EQ(time_point<sys_seconds>::max(), tp);
+  tp = convert(civil_second::max(), west);
+  EXPECT_EQ(time_point<sys_seconds>::max(), tp);
+
+  // Approach the minimal time_point<sys_seconds> value from above.
+  tp = convert(civil_second(-292277022657, 1, 27, 8, 29, 53), utc);
+  EXPECT_EQ("-292277022657-01-27T08:29:53+00:00", format(RFC3339, tp, utc));
+  tp = convert(civil_second(-292277022657, 1, 27, 8, 29, 52), utc);
+  EXPECT_EQ("-292277022657-01-27T08:29:52+00:00", format(RFC3339, tp, utc));
+  EXPECT_EQ(time_point<sys_seconds>::min(), tp);
+  tp = convert(civil_second(-292277022657, 1, 27, 8, 29, 51), utc);
+  EXPECT_EQ(time_point<sys_seconds>::min(), tp);
+  tp = convert(civil_second::min(), utc);
+  EXPECT_EQ(time_point<sys_seconds>::min(), tp);
+
+  // Checks that we can also get the minimal value for a far-east zone.
+  tp = convert(civil_second(-292277022657, 1, 27, 22, 29, 52), east);
+  EXPECT_EQ("-292277022657-01-27T22:29:52+14:00", format(RFC3339, tp, east));
+  EXPECT_EQ(time_point<sys_seconds>::min(), tp);
+  tp = convert(civil_second(-292277022657, 1, 27, 22, 29, 51), east);
+  EXPECT_EQ(time_point<sys_seconds>::min(), tp);
+  tp = convert(civil_second::min(), east);
+  EXPECT_EQ(time_point<sys_seconds>::min(), tp);
+
+  // Checks that we can also get the minimal value for a far-west zone.
+  tp = convert(civil_second(-292277022657, 1, 26, 18, 29, 52), west);
+  EXPECT_EQ("-292277022657-01-26T18:29:52-14:00", format(RFC3339, tp, west));
+  EXPECT_EQ(time_point<sys_seconds>::min(), tp);
+  tp = convert(civil_second(-292277022657, 1, 26, 18, 29, 51), west);
+  EXPECT_EQ(time_point<sys_seconds>::min(), tp);
+  tp = convert(civil_second::min(), west);
+  EXPECT_EQ(time_point<sys_seconds>::min(), tp);
+}
+
+TEST(TimeZoneEdgeCase, AmericaNewYork) {
+  const time_zone tz = LoadZone("America/New_York");
+
+  // Spring 1:59:59 -> 3:00:00
+  auto tp = convert(civil_second(2013, 3, 10, 1, 59, 59), tz);
+  ExpectTime(tp, tz, 2013, 3, 10, 1, 59, 59, -5 * 3600, false, "EST");
+  tp += seconds(1);
+  ExpectTime(tp, tz, 2013, 3, 10, 3, 0, 0, -4 * 3600, true, "EDT");
+
+  // Fall 1:59:59 -> 1:00:00
+  tp = convert(civil_second(2013, 11, 3, 1, 59, 59), tz);
+  ExpectTime(tp, tz, 2013, 11, 3, 1, 59, 59, -4 * 3600, true, "EDT");
+  tp += seconds(1);
+  ExpectTime(tp, tz, 2013, 11, 3, 1, 0, 0, -5 * 3600, false, "EST");
+}
+
+TEST(TimeZoneEdgeCase, AmericaLosAngeles) {
+  const time_zone tz = LoadZone("America/Los_Angeles");
+
+  // Spring 1:59:59 -> 3:00:00
+  auto tp = convert(civil_second(2013, 3, 10, 1, 59, 59), tz);
+  ExpectTime(tp, tz, 2013, 3, 10, 1, 59, 59, -8 * 3600, false, "PST");
+  tp += seconds(1);
+  ExpectTime(tp, tz, 2013, 3, 10, 3, 0, 0, -7 * 3600, true, "PDT");
+
+  // Fall 1:59:59 -> 1:00:00
+  tp = convert(civil_second(2013, 11, 3, 1, 59, 59), tz);
+  ExpectTime(tp, tz, 2013, 11, 3, 1, 59, 59, -7 * 3600, true, "PDT");
+  tp += seconds(1);
+  ExpectTime(tp, tz, 2013, 11, 3, 1, 0, 0, -8 * 3600, false, "PST");
+}
+
+TEST(TimeZoneEdgeCase, ArizonaNoTransition) {
+  const time_zone tz = LoadZone("America/Phoenix");
+
+  // No transition in Spring.
+  auto tp = convert(civil_second(2013, 3, 10, 1, 59, 59), tz);
+  ExpectTime(tp, tz, 2013, 3, 10, 1, 59, 59, -7 * 3600, false, "MST");
+  tp += seconds(1);
+  ExpectTime(tp, tz, 2013, 3, 10, 2, 0, 0, -7 * 3600, false, "MST");
+
+  // No transition in Fall.
+  tp = convert(civil_second(2013, 11, 3, 1, 59, 59), tz);
+  ExpectTime(tp, tz, 2013, 11, 3, 1, 59, 59, -7 * 3600, false, "MST");
+  tp += seconds(1);
+  ExpectTime(tp, tz, 2013, 11, 3, 2, 0, 0, -7 * 3600, false, "MST");
+}
+
+TEST(TimeZoneEdgeCase, AsiaKathmandu) {
+  const time_zone tz = LoadZone("Asia/Kathmandu");
+
+  // A non-DST offset change from +0530 to +0545
+  //
+  //   504901799 == Tue, 31 Dec 1985 23:59:59 +0530 (+0530)
+  //   504901800 == Wed,  1 Jan 1986 00:15:00 +0545 (+0545)
+  auto tp = convert(civil_second(1985, 12, 31, 23, 59, 59), tz);
+  ExpectTime(tp, tz, 1985, 12, 31, 23, 59, 59, 5.5 * 3600, false, "+0530");
+  tp += seconds(1);
+  ExpectTime(tp, tz, 1986, 1, 1, 0, 15, 0, 5.75 * 3600, false, "+0545");
+}
+
+TEST(TimeZoneEdgeCase, PacificChatham) {
+  const time_zone tz = LoadZone("Pacific/Chatham");
+
+  // One-hour DST offset changes, but at atypical values
+  //
+  //   1365256799 == Sun,  7 Apr 2013 03:44:59 +1345 (+1345)
+  //   1365256800 == Sun,  7 Apr 2013 02:45:00 +1245 (+1245)
+  auto tp = convert(civil_second(2013, 4, 7, 3, 44, 59), tz);
+  ExpectTime(tp, tz, 2013, 4, 7, 3, 44, 59, 13.75 * 3600, true, "+1345");
+  tp += seconds(1);
+  ExpectTime(tp, tz, 2013, 4, 7, 2, 45, 0, 12.75 * 3600, false, "+1245");
+
+  //   1380376799 == Sun, 29 Sep 2013 02:44:59 +1245 (+1245)
+  //   1380376800 == Sun, 29 Sep 2013 03:45:00 +1345 (+1345)
+  tp = convert(civil_second(2013, 9, 29, 2, 44, 59), tz);
+  ExpectTime(tp, tz, 2013, 9, 29, 2, 44, 59, 12.75 * 3600, false, "+1245");
+  tp += seconds(1);
+  ExpectTime(tp, tz, 2013, 9, 29, 3, 45, 0, 13.75 * 3600, true, "+1345");
+}
+
+TEST(TimeZoneEdgeCase, AustraliaLordHowe) {
+  const time_zone tz = LoadZone("Australia/Lord_Howe");
+
+  // Half-hour DST offset changes
+  //
+  //   1365260399 == Sun,  7 Apr 2013 01:59:59 +1100 (+11)
+  //   1365260400 == Sun,  7 Apr 2013 01:30:00 +1030 (+1030)
+  auto tp = convert(civil_second(2013, 4, 7, 1, 59, 59), tz);
+  ExpectTime(tp, tz, 2013, 4, 7, 1, 59, 59, 11 * 3600, true, "+11");
+  tp += seconds(1);
+  ExpectTime(tp, tz, 2013, 4, 7, 1, 30, 0, 10.5 * 3600, false, "+1030");
+
+  //   1380986999 == Sun,  6 Oct 2013 01:59:59 +1030 (+1030)
+  //   1380987000 == Sun,  6 Oct 2013 02:30:00 +1100 (+11)
+  tp = convert(civil_second(2013, 10, 6, 1, 59, 59), tz);
+  ExpectTime(tp, tz, 2013, 10, 6, 1, 59, 59, 10.5 * 3600, false, "+1030");
+  tp += seconds(1);
+  ExpectTime(tp, tz, 2013, 10, 6, 2, 30, 0, 11 * 3600, true, "+11");
+}
+
+TEST(TimeZoneEdgeCase, PacificApia) {
+  const time_zone tz = LoadZone("Pacific/Apia");
+
+  // At the end of December 2011, Samoa jumped forward by one day,
+  // skipping 30 December from the local calendar, when the nation
+  // moved to the west of the International Date Line.
+  //
+  // A one-day, non-DST offset change
+  //
+  //   1325239199 == Thu, 29 Dec 2011 23:59:59 -1000 (-10)
+  //   1325239200 == Sat, 31 Dec 2011 00:00:00 +1400 (+14)
+  auto tp = convert(civil_second(2011, 12, 29, 23, 59, 59), tz);
+  ExpectTime(tp, tz, 2011, 12, 29, 23, 59, 59, -10 * 3600, true, "-10");
+  EXPECT_EQ(363, get_yearday(civil_day(convert(tp, tz))));
+  tp += seconds(1);
+  ExpectTime(tp, tz, 2011, 12, 31, 0, 0, 0, 14 * 3600, true, "+14");
+  EXPECT_EQ(365, get_yearday(civil_day(convert(tp, tz))));
+}
+
+TEST(TimeZoneEdgeCase, AfricaCairo) {
+  const time_zone tz = LoadZone("Africa/Cairo");
+
+  // An interesting case of midnight not existing.
+  //
+  //   1400191199 == Thu, 15 May 2014 23:59:59 +0200 (EET)
+  //   1400191200 == Fri, 16 May 2014 01:00:00 +0300 (EEST)
+  auto tp = convert(civil_second(2014, 5, 15, 23, 59, 59), tz);
+  ExpectTime(tp, tz, 2014, 5, 15, 23, 59, 59, 2 * 3600, false, "EET");
+  tp += seconds(1);
+  ExpectTime(tp, tz, 2014, 5, 16, 1, 0, 0, 3 * 3600, true, "EEST");
+}
+
+TEST(TimeZoneEdgeCase, AfricaMonrovia) {
+  const time_zone tz = LoadZone("Africa/Monrovia");
+
+  // Strange offset change -00:44:30 -> +00:00:00 (non-DST)
+  //
+  //   63593069 == Thu,  6 Jan 1972 23:59:59 -0044 (MMT)
+  //   63593070 == Fri,  7 Jan 1972 00:44:30 +0000 (GMT)
+  auto tp = convert(civil_second(1972, 1, 6, 23, 59, 59), tz);
+  ExpectTime(tp, tz, 1972, 1, 6, 23, 59, 59, -44.5 * 60, false, "MMT");
+  tp += seconds(1);
+#ifndef TZDATA_2017B_IS_UBIQUITOUS
+  // The 2017b tzdata release moved the shift from -004430 to +00
+  // from 1972-05-01 to 1972-01-07, so we temporarily accept both
+  // outcomes until 2017b is ubiquitous.
+  if (tz.lookup(tp).offset == -44.5 * 60) {
+    tp = convert(civil_second(1972, 4, 30, 23, 59, 59), tz);
+    ExpectTime(tp, tz, 1972, 4, 30, 23, 59, 59, -44.5 * 60, false, "LRT");
+    tp += seconds(1);
+    ExpectTime(tp, tz, 1972, 5, 1, 0, 44, 30, 0 * 60, false, "GMT");
+    return;
+  }
+#endif
+  ExpectTime(tp, tz, 1972, 1, 7, 0, 44, 30, 0 * 60, false, "GMT");
+}
+
+TEST(TimeZoneEdgeCase, AmericaJamaica) {
+  // Jamaica discontinued DST transitions in 1983, and is now at a
+  // constant -0500.  This makes it an interesting edge-case target.
+  // Note that the 32-bit times used in a (tzh_version == 0) zoneinfo
+  // file cannot represent the abbreviation-only transition of 1890,
+  // so we ignore the abbreviation by expecting what we received.
+  const time_zone tz = LoadZone("America/Jamaica");
+
+  // Before the first transition.
+  auto tp = convert(civil_second(1889, 12, 31, 0, 0, 0), tz);
+#if AMERICA_JAMAICA_PRE_1913_OFFSET_FIX
+  // Commit 907241e: Fix off-by-1 error for Jamaica and T&C before 1913.
+  // Until that commit has made its way into a full release we avoid the
+  // expectations on the -18430 offset below.  TODO: Uncomment these.
+  ExpectTime(tp, tz, 1889, 12, 31, 0, 0, 0, -18430, false,
+             tz.lookup(tp).abbr);
+
+  // Over the first (abbreviation-change only) transition.
+  //   -2524503170 == Tue, 31 Dec 1889 23:59:59 -0507 (LMT)
+  //   -2524503169 == Wed,  1 Jan 1890 00:00:00 -0507 (KMT)
+  tp = convert(civil_second(1889, 12, 31, 23, 59, 59), tz);
+  ExpectTime(tp, tz, 1889, 12, 31, 23, 59, 59, -18430, false,
+             tz.lookup(tp).abbr);
+  tp += seconds(1);
+  ExpectTime(tp, tz, 1890, 1, 1, 0, 0, 0, -18430, false, "KMT");
+#endif
+
+  // Over the last (DST) transition.
+  //     436341599 == Sun, 30 Oct 1983 01:59:59 -0400 (EDT)
+  //     436341600 == Sun, 30 Oct 1983 01:00:00 -0500 (EST)
+  tp = convert(civil_second(1983, 10, 30, 1, 59, 59), tz);
+  ExpectTime(tp, tz, 1983, 10, 30, 1, 59, 59, -4 * 3600, true, "EDT");
+  tp += seconds(1);
+  ExpectTime(tp, tz, 1983, 10, 30, 1, 0, 0, -5 * 3600, false, "EST");
+
+  // After the last transition.
+  tp = convert(civil_second(1983, 12, 31, 23, 59, 59), tz);
+  ExpectTime(tp, tz, 1983, 12, 31, 23, 59, 59, -5 * 3600, false, "EST");
+}
+
+TEST(TimeZoneEdgeCase, WET) {
+  // Cover some non-existent times within forward transitions.
+  const time_zone tz = LoadZone("WET");
+
+  // Before the first transition.
+  auto tp = convert(civil_second(1977, 1, 1, 0, 0, 0), tz);
+  ExpectTime(tp, tz, 1977, 1, 1, 0, 0, 0, 0, false, "WET");
+
+  // Over the first transition.
+  //     228877199 == Sun,  3 Apr 1977 00:59:59 +0000 (WET)
+  //     228877200 == Sun,  3 Apr 1977 02:00:00 +0100 (WEST)
+  tp = convert(civil_second(1977, 4, 3, 0, 59, 59), tz);
+  ExpectTime(tp, tz, 1977, 4, 3, 0, 59, 59, 0, false, "WET");
+  tp += seconds(1);
+  ExpectTime(tp, tz, 1977, 4, 3, 2, 0, 0, 1 * 3600, true, "WEST");
+
+  // A non-existent time within the first transition.
+  time_zone::civil_lookup cl1 = tz.lookup(civil_second(1977, 4, 3, 1, 15, 0));
+  EXPECT_EQ(time_zone::civil_lookup::SKIPPED, cl1.kind);
+  ExpectTime(cl1.pre, tz, 1977, 4, 3, 2, 15, 0, 1 * 3600, true, "WEST");
+  ExpectTime(cl1.trans, tz, 1977, 4, 3, 2, 0, 0, 1 * 3600, true, "WEST");
+  ExpectTime(cl1.post, tz, 1977, 4, 3, 0, 15, 0, 0 * 3600, false, "WET");
+
+  // A non-existent time within the second forward transition.
+  time_zone::civil_lookup cl2 = tz.lookup(civil_second(1978, 4, 2, 1, 15, 0));
+  EXPECT_EQ(time_zone::civil_lookup::SKIPPED, cl2.kind);
+  ExpectTime(cl2.pre, tz, 1978, 4, 2, 2, 15, 0, 1 * 3600, true, "WEST");
+  ExpectTime(cl2.trans, tz, 1978, 4, 2, 2, 0, 0, 1 * 3600, true, "WEST");
+  ExpectTime(cl2.post, tz, 1978, 4, 2, 0, 15, 0, 0 * 3600, false, "WET");
+}
+
+TEST(TimeZoneEdgeCase, FixedOffsets) {
+  const time_zone gmtm5 = LoadZone("Etc/GMT+5");  // -0500
+  auto tp = convert(civil_second(1970, 1, 1, 0, 0, 0), gmtm5);
+  ExpectTime(tp, gmtm5, 1970, 1, 1, 0, 0, 0, -5 * 3600, false, "-05");
+  EXPECT_EQ(system_clock::from_time_t(5 * 3600), tp);
+
+  const time_zone gmtp5 = LoadZone("Etc/GMT-5");  // +0500
+  tp = convert(civil_second(1970, 1, 1, 0, 0, 0), gmtp5);
+  ExpectTime(tp, gmtp5, 1970, 1, 1, 0, 0, 0, 5 * 3600, false, "+05");
+  EXPECT_EQ(system_clock::from_time_t(-5 * 3600), tp);
+}
+
+TEST(TimeZoneEdgeCase, NegativeYear) {
+  // Tests transition from year 0 (aka 1BCE) to year -1.
+  const time_zone tz = utc_time_zone();
+  auto tp = convert(civil_second(0, 1, 1, 0, 0, 0), tz);
+  ExpectTime(tp, tz, 0, 1, 1, 0, 0, 0, 0 * 3600, false, "UTC");
+  EXPECT_EQ(weekday::saturday, get_weekday(civil_day(convert(tp, tz))));
+  tp -= seconds(1);
+  ExpectTime(tp, tz, -1, 12, 31, 23, 59, 59, 0 * 3600, false, "UTC");
+  EXPECT_EQ(weekday::friday, get_weekday(civil_day(convert(tp, tz))));
+}
+
+TEST(TimeZoneEdgeCase, UTC32bitLimit) {
+  const time_zone tz = utc_time_zone();
+
+  // Limits of signed 32-bit time_t
+  //
+  //   2147483647 == Tue, 19 Jan 2038 03:14:07 +0000 (UTC)
+  //   2147483648 == Tue, 19 Jan 2038 03:14:08 +0000 (UTC)
+  auto tp = convert(civil_second(2038, 1, 19, 3, 14, 7), tz);
+  ExpectTime(tp, tz, 2038, 1, 19, 3, 14, 7, 0 * 3600, false, "UTC");
+  tp += seconds(1);
+  ExpectTime(tp, tz, 2038, 1, 19, 3, 14, 8, 0 * 3600, false, "UTC");
+}
+
+TEST(TimeZoneEdgeCase, UTC5DigitYear) {
+  const time_zone tz = utc_time_zone();
+
+  // Rollover to 5-digit year
+  //
+  //   253402300799 == Fri, 31 Dec 9999 23:59:59 +0000 (UTC)
+  //   253402300800 == Sat,  1 Jan 1000 00:00:00 +0000 (UTC)
+  auto tp = convert(civil_second(9999, 12, 31, 23, 59, 59), tz);
+  ExpectTime(tp, tz, 9999, 12, 31, 23, 59, 59, 0 * 3600, false, "UTC");
+  tp += seconds(1);
+  ExpectTime(tp, tz, 10000, 1, 1, 0, 0, 0, 0 * 3600, false, "UTC");
+}
+
+}  // namespace cctz
+}  // namespace time_internal
+}  // namespace absl