- fd5f3d7077270ffc5ea74cdb9e18bbae3b9b46aa Fix typo optional -> variant by…

  - 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

CMake/AbseilHelpers.cmake

@@ -34,7 +34,7 @@ function(absl_library)
   cmake_parse_arguments(ABSL_LIB
     "DISABLE_INSTALL" # keep that in case we want to support installation one day
     "TARGET;EXPORT_NAME"
-    "SOURCES;PUBLIC_LIBRARIES;PRIVATE_COMPILE_FLAGS;PUBLIC_INCLUDE_DIRS;PRIVATE_INCLUDE_DIRS"
+    "SOURCES;PUBLIC_LIBRARIES;PRIVATE_COMPILE_FLAGS"
     ${ARGN}
   )
 

CMake/README.md

@@ -19,10 +19,8 @@ googletest framework
 
 ### Step-by-Step Instructions
 
-1. If you haven't done so already, integrate the Abseil dependency
-[CCTZ](https://github.com/google/cctz) into your CMake project. Consequently, the
-target 'cctz' needs to be declared in your CMake project **before** including Abseil.<br>
-Note: If you want to build the Abseil tests, you'll also need [Google Test](https://github.com/google/googletest). To disable Abseil tests, you have to pass
+1. If you want to build the Abseil tests, integrate the Abseil dependency
+[Google Test](https://github.com/google/googletest) into your CMake project. To disable Abseil tests, you have to pass
 `-DBUILD_TESTING=OFF` when configuring your project with CMake.
 
 2. Download Abseil and copy it into a subdirectory in your CMake project or add
@@ -31,8 +29,7 @@ CMake project.
 
 3. You can then use the CMake command
 [`add_subdirectory()`](https://cmake.org/cmake/help/latest/command/add_subdirectory.html)
-to include Abseil directly in your CMake project. In addition, it's possible to
-customize the name of the `cctz` target with the `-DABSL_CCTZ_TARGET=*my_cctz*` option.
+to include Abseil directly in your CMake project.
 
 4. Add the **absl::** target you wish to use to the
 [`target_link_libraries()`](https://cmake.org/cmake/help/latest/command/target_link_libraries.html)

CMakeLists.txt

@@ -65,15 +65,9 @@ set(ABSL_EXCEPTIONS_FLAG "${CMAKE_CXX_EXCEPTIONS}")
 ## pthread
 find_package(Threads REQUIRED)
 
-if(NOT ABSL_CCTZ_TARGET)
-  set(ABSL_CCTZ_TARGET cctz)
-endif()
-
 # commented: used only for standalone test
 # Don't remove these or else CMake CI will break
-#add_subdirectory(cctz)
 #add_subdirectory(googletest)
-check_target(${ABSL_CCTZ_TARGET})
 
 ## check targets
 if(BUILD_TESTING)

WORKSPACE

@@ -17,13 +17,6 @@ http_archive(
      strip_prefix = "googletest-master",
 )
 
-# CCTZ (Time-zone framework).
-http_archive(
-    name = "com_googlesource_code_cctz",
-    urls = ["https://github.com/google/cctz/archive/master.zip"],
-    strip_prefix = "cctz-master",
-)
-
 # RE2 regular-expression framework. Used by some unit-tests.
 http_archive(
     name = "com_googlesource_code_re2",

absl/base/config.h

@@ -384,7 +384,7 @@
 
 // ABSL_HAVE_STD_VARIANT
 //
-// Checks whether C++17 std::optional is available.
+// Checks whether C++17 std::variant is available.
 #ifdef ABSL_HAVE_STD_VARIANT
 #error "ABSL_HAVE_STD_VARIANT cannot be directly set."
 #endif

absl/strings/str_cat_test.cc

@@ -206,6 +206,8 @@ struct Mallocator {
     typedef Mallocator<U> other;
   };
   Mallocator() = default;
+  template <class U>
+  Mallocator(const Mallocator<U>&) {}  // NOLINT(runtime/explicit)
 
   T* allocate(size_t n) { return static_cast<T*>(std::malloc(n * sizeof(T))); }
   void deallocate(T* p, size_t) { std::free(p); }

absl/strings/string_view_test.cc

@@ -50,6 +50,8 @@ struct Mallocator {
     typedef Mallocator<U> other;
   };
   Mallocator() = default;
+  template <class U>
+  Mallocator(const Mallocator<U>&) {}  // NOLINT(runtime/explicit)
 
   T* allocate(size_t n) { return static_cast<T*>(std::malloc(n * sizeof(T))); }
   void deallocate(T* p, size_t) { std::free(p); }

absl/time/BUILD.bazel

@@ -44,8 +44,8 @@ cc_library(
         "//absl/base",
         "//absl/base:core_headers",
         "//absl/numeric:int128",
-        "@com_googlesource_code_cctz//:civil_time",
-        "@com_googlesource_code_cctz//:time_zone",
+        "//absl/time/internal/cctz:civil_time",
+        "//absl/time/internal/cctz:time_zone",
     ],
 )
 
@@ -63,7 +63,7 @@ cc_library(
     deps = [
         ":time",
         "//absl/base",
-        "@com_googlesource_code_cctz//:time_zone",
+        "//absl/time/internal/cctz:time_zone",
     ],
 )
 
@@ -91,7 +91,7 @@ cc_test(
         "//absl/base",
         "//absl/base:config",
         "//absl/base:core_headers",
+        "//absl/time/internal/cctz:time_zone",
         "@com_google_googletest//:gtest_main",
-        "@com_googlesource_code_cctz//:time_zone",
     ],
 )

absl/time/CMakeLists.txt

@@ -22,6 +22,10 @@ list(APPEND TIME_PUBLIC_HEADERS
 
 list(APPEND TIME_INTERNAL_HEADERS
   "internal/test_util.h"
+  "internal/cctz/include/cctz/civil_time.h"
+  "internal/cctz/include/cctz/civil_time_detail.h"
+  "internal/cctz/include/cctz/time_zone.h"
+  "internal/cctz/include/cctz/zone_info_source.h"
 )
 
 list(APPEND TIME_SRC
@@ -29,10 +33,27 @@ list(APPEND TIME_SRC
   "clock.cc"
   "duration.cc"
   "format.cc"
+  "internal/cctz/src/civil_time_detail.cc"
+  "internal/cctz/src/time_zone_fixed.cc"
+  "internal/cctz/src/time_zone_fixed.h"
+  "internal/cctz/src/time_zone_format.cc"
+  "internal/cctz/src/time_zone_if.cc"
+  "internal/cctz/src/time_zone_if.h"
+  "internal/cctz/src/time_zone_impl.cc"
+  "internal/cctz/src/time_zone_impl.h"
+  "internal/cctz/src/time_zone_info.cc"
+  "internal/cctz/src/time_zone_info.h"
+  "internal/cctz/src/time_zone_libc.cc"
+  "internal/cctz/src/time_zone_libc.h"
+  "internal/cctz/src/time_zone_lookup.cc"
+  "internal/cctz/src/time_zone_posix.cc"
+  "internal/cctz/src/time_zone_posix.h"
+  "internal/cctz/src/tzfile.h"
+  "internal/cctz/src/zone_info_source.cc"
   ${TIME_PUBLIC_HEADERS}
   ${TIME_INTERNAL_HEADERS}
 )
-set(TIME_PUBLIC_LIBRARIES absl::base absl::stacktrace absl::int128 ${ABSL_CCTZ_TARGET})
+set(TIME_PUBLIC_LIBRARIES absl::base absl::stacktrace absl::int128)
 
 absl_library(
   TARGET
@@ -41,8 +62,6 @@ absl_library(
     ${TIME_SRC}
   PUBLIC_LIBRARIES
     ${TIME_PUBLIC_LIBRARIES}
-  PUBLIC_INCLUDE_DIRS
-    ${CCTZ_INCLUDE_DIRS}
   EXPORT_NAME
     time
 )

absl/time/format.cc

@@ -16,8 +16,10 @@
 #include <cctype>
 #include <cstdint>
 
+#include "absl/time/internal/cctz/include/cctz/time_zone.h"
 #include "absl/time/time.h"
-#include "cctz/time_zone.h"
+
+namespace cctz = absl::time_internal::cctz;
 
 namespace absl {
 

absl/time/internal/cctz/BUILD.bazel

+# 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.
+
+licenses(["notice"])  # Apache License
+
+### libraries
+
+cc_library(
+    name = "includes",
+    textual_hdrs = [
+        "include/cctz/civil_time.h",
+        "include/cctz/civil_time_detail.h",
+        "include/cctz/time_zone.h",
+    ],
+    visibility = ["//absl/time:__pkg__"],
+)
+
+cc_library(
+    name = "civil_time",
+    srcs = ["src/civil_time_detail.cc"],
+    hdrs = [
+        "include/cctz/civil_time.h",
+    ],
+    textual_hdrs = ["include/cctz/civil_time_detail.h"],
+    visibility = ["//visibility:public"],
+)
+
+cc_library(
+    name = "time_zone",
+    srcs = [
+        "src/time_zone_fixed.cc",
+        "src/time_zone_fixed.h",
+        "src/time_zone_format.cc",
+        "src/time_zone_if.cc",
+        "src/time_zone_if.h",
+        "src/time_zone_impl.cc",
+        "src/time_zone_impl.h",
+        "src/time_zone_info.cc",
+        "src/time_zone_info.h",
+        "src/time_zone_libc.cc",
+        "src/time_zone_libc.h",
+        "src/time_zone_lookup.cc",
+        "src/time_zone_posix.cc",
+        "src/time_zone_posix.h",
+        "src/tzfile.h",
+        "src/zone_info_source.cc",
+    ],
+    hdrs = [
+        "include/cctz/time_zone.h",
+        "include/cctz/zone_info_source.h",
+    ],
+    visibility = ["//visibility:public"],
+    deps = [":civil_time"],
+)
+
+### tests
+
+cc_test(
+    name = "civil_time_test",
+    size = "small",
+    srcs = ["src/civil_time_test.cc"],
+    deps = [
+        ":civil_time",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+cc_test(
+    name = "time_zone_format_test",
+    size = "small",
+    srcs = ["src/time_zone_format_test.cc"],
+    deps = [
+        ":civil_time",
+        ":time_zone",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+cc_test(
+    name = "time_zone_lookup_test",
+    size = "small",
+    srcs = ["src/time_zone_lookup_test.cc"],
+    deps = [
+        ":civil_time",
+        ":time_zone",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+### benchmarks
+
+### examples
+
+### binaries

absl/time/internal/cctz/include/cctz/zone_info_source.h

+// 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.
+
+#ifndef ABSL_TIME_INTERNAL_CCTZ_ZONE_INFO_SOURCE_H_
+#define ABSL_TIME_INTERNAL_CCTZ_ZONE_INFO_SOURCE_H_
+
+#include <cstddef>
+#include <functional>
+#include <memory>
+#include <string>
+
+namespace absl {
+namespace time_internal {
+namespace cctz {
+
+// A stdio-like interface for providing zoneinfo data for a particular zone.
+class ZoneInfoSource {
+ public:
+  virtual ~ZoneInfoSource();
+
+  virtual std::size_t Read(void* ptr, std::size_t size) = 0;  // like fread()
+  virtual int Skip(std::size_t offset) = 0;  // like fseek()
+};
+
+}  // namespace cctz
+}  // namespace time_internal
+}  // namespace absl
+
+namespace absl {
+namespace time_internal {
+namespace cctz_extension {
+
+// A function-pointer type for a factory that returns a ZoneInfoSource
+// given the name of a time zone and a fallback factory.  Returns null
+// when the data for the named zone cannot be found.
+using ZoneInfoSourceFactory =
+    std::unique_ptr<absl::time_internal::cctz::ZoneInfoSource> (*)(
+        const std::string&,
+        const std::function<std::unique_ptr<absl::time_internal::cctz::ZoneInfoSource>(
+            const std::string&)>&);
+
+// The user can control the mapping of zone names to zoneinfo data by
+// providing a definition for cctz_extension::zone_info_source_factory.
+// For example, given functions my_factory() and my_other_factory() that
+// can return a ZoneInfoSource for a named zone, we could inject them into
+// cctz::load_time_zone() with:
+//
+//   namespace cctz_extension {
+//   namespace {
+//   std::unique_ptr<cctz::ZoneInfoSource> CustomFactory(
+//       const std::string& name,
+//       const std::function<std::unique_ptr<cctz::ZoneInfoSource>(
+//           const std::string& name)>& fallback_factory) {
+//     if (auto zip = my_factory(name)) return zip;
+//     if (auto zip = fallback_factory(name)) return zip;
+//     if (auto zip = my_other_factory(name)) return zip;
+//     return nullptr;
+//   }
+//   }  // namespace
+//   ZoneInfoSourceFactory zone_info_source_factory = CustomFactory;
+//   }  // namespace cctz_extension
+//
+// This might be used, say, to use zoneinfo data embedded in the program,
+// or read from a (possibly compressed) file archive, or both.
+//
+// cctz_extension::zone_info_source_factory() will be called:
+//   (1) from the same thread as the cctz::load_time_zone() call,
+//   (2) only once for any zone name, and
+//   (3) serially (i.e., no concurrent execution).
+//
+// The fallback factory obtains zoneinfo data by reading files in ${TZDIR},
+// and it is used automatically when no zone_info_source_factory definition
+// is linked into the program.
+extern ZoneInfoSourceFactory zone_info_source_factory;
+
+}  // namespace cctz_extension
+}  // namespace time_internal
+}  // namespace absl
+
+#endif  // ABSL_TIME_INTERNAL_CCTZ_ZONE_INFO_SOURCE_H_

absl/time/internal/cctz/src/civil_time_detail.cc

+// 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/civil_time_detail.h"
+
+#include <iomanip>
+#include <ostream>
+#include <sstream>
+
+namespace absl {
+namespace time_internal {
+namespace cctz {
+namespace detail {
+
+// Output stream operators output a format matching YYYY-MM-DDThh:mm:ss,
+// while omitting fields inferior to the type's alignment. For example,
+// civil_day is formatted only as YYYY-MM-DD.
+std::ostream& operator<<(std::ostream& os, const civil_year& y) {
+  std::stringstream ss;
+  ss << y.year();  // No padding.
+  return os << ss.str();
+}
+std::ostream& operator<<(std::ostream& os, const civil_month& m) {
+  std::stringstream ss;
+  ss << civil_year(m) << '-';
+  ss << std::setfill('0') << std::setw(2) << m.month();
+  return os << ss.str();
+}
+std::ostream& operator<<(std::ostream& os, const civil_day& d) {
+  std::stringstream ss;
+  ss << civil_month(d) << '-';
+  ss << std::setfill('0') << std::setw(2) << d.day();
+  return os << ss.str();
+}
+std::ostream& operator<<(std::ostream& os, const civil_hour& h) {
+  std::stringstream ss;
+  ss << civil_day(h) << 'T';
+  ss << std::setfill('0') << std::setw(2) << h.hour();
+  return os << ss.str();
+}
+std::ostream& operator<<(std::ostream& os, const civil_minute& m) {
+  std::stringstream ss;
+  ss << civil_hour(m) << ':';
+  ss << std::setfill('0') << std::setw(2) << m.minute();
+  return os << ss.str();
+}
+std::ostream& operator<<(std::ostream& os, const civil_second& s) {
+  std::stringstream ss;
+  ss << civil_minute(s) << ':';
+  ss << std::setfill('0') << std::setw(2) << s.second();
+  return os << ss.str();
+}
+
+////////////////////////////////////////////////////////////////////////
+
+std::ostream& operator<<(std::ostream& os, weekday wd) {
+  switch (wd) {
+    case weekday::monday:
+      return os << "Monday";
+    case weekday::tuesday:
+      return os << "Tuesday";
+    case weekday::wednesday:
+      return os << "Wednesday";
+    case weekday::thursday:
+      return os << "Thursday";
+    case weekday::friday:
+      return os << "Friday";
+    case weekday::saturday:
+      return os << "Saturday";
+    case weekday::sunday:
+      return os << "Sunday";
+  }
+  return os;  // Should never get here, but -Wreturn-type may warn without this.
+}
+
+}  // namespace detail
+}  // namespace cctz
+}  // namespace time_internal
+}  // namespace absl

absl/time/internal/cctz/src/time_zone_fixed.cc

+// 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 "time_zone_fixed.h"
+
+#include <algorithm>
+#include <chrono>
+#include <cstdio>
+#include <cstring>
+#include <string>
+
+namespace absl {
+namespace time_internal {
+namespace cctz {
+
+namespace {
+
+// The prefix used for the internal names of fixed-offset zones.
+const char kFixedOffsetPrefix[] = "Fixed/";
+
+int Parse02d(const char* p) {
+  static const char kDigits[] = "0123456789";
+  if (const char* ap = std::strchr(kDigits, *p)) {
+    int v = static_cast<int>(ap - kDigits);
+    if (const char* bp = std::strchr(kDigits, *++p)) {
+      return (v * 10) + static_cast<int>(bp - kDigits);
+    }
+  }
+  return -1;
+}
+
+}  // namespace
+
+bool FixedOffsetFromName(const std::string& name, sys_seconds* offset) {
+  if (name.compare(0, std::string::npos, "UTC", 3) == 0) {
+    *offset = sys_seconds::zero();
+    return true;
+  }
+
+  const std::size_t prefix_len = sizeof(kFixedOffsetPrefix) - 1;
+  const char* const ep = kFixedOffsetPrefix + prefix_len;
+  if (name.size() != prefix_len + 12)  // "<prefix>UTC+99:99:99"
+    return false;
+  if (!std::equal(kFixedOffsetPrefix, ep, name.begin()))
+    return false;
+  const char* np = name.data() + prefix_len;
+  if (*np++ != 'U' || *np++ != 'T' || *np++ != 'C')
+    return false;
+  if (np[0] != '+' && np[0] != '-')
+    return false;
+  if (np[3] != ':' || np[6] != ':')  // see note below about large offsets
+    return false;
+
+  int hours = Parse02d(np + 1);
+  if (hours == -1) return false;
+  int mins = Parse02d(np + 4);
+  if (mins == -1) return false;
+  int secs = Parse02d(np + 7);
+  if (secs == -1) return false;
+
+  secs += ((hours * 60) + mins) * 60;
+  if (secs > 24 * 60 * 60) return false;  // outside supported offset range
+  *offset = sys_seconds(secs * (np[0] == '-' ? -1 : 1));  // "-" means west
+  return true;
+}
+
+std::string FixedOffsetToName(const sys_seconds& offset) {
+  if (offset == sys_seconds::zero()) return "UTC";
+  if (offset < std::chrono::hours(-24) || offset > std::chrono::hours(24)) {
+    // We don't support fixed-offset zones more than 24 hours
+    // away from UTC to avoid complications in rendering such
+    // offsets and to (somewhat) limit the total number of zones.
+    return "UTC";
+  }
+  int seconds = static_cast<int>(offset.count());
+  const char sign = (seconds < 0 ? '-' : '+');
+  int minutes = seconds / 60;
+  seconds %= 60;
+  if (sign == '-') {
+    if (seconds > 0) {
+      seconds -= 60;
+      minutes += 1;
+    }
+    seconds = -seconds;
+    minutes = -minutes;
+  }
+  int hours = minutes / 60;
+  minutes %= 60;
+  char buf[sizeof(kFixedOffsetPrefix) + sizeof("UTC-24:00:00")];
+  snprintf(buf, sizeof(buf), "%sUTC%c%02d:%02d:%02d",
+           kFixedOffsetPrefix, sign, hours, minutes, seconds);
+  return buf;
+}
+
+std::string FixedOffsetToAbbr(const sys_seconds& offset) {
+  std::string abbr = FixedOffsetToName(offset);
+  const std::size_t prefix_len = sizeof(kFixedOffsetPrefix) - 1;
+  const char* const ep = kFixedOffsetPrefix + prefix_len;
+  if (abbr.size() >= prefix_len) {
+    if (std::equal(kFixedOffsetPrefix, ep, abbr.begin())) {
+      abbr.erase(0, prefix_len);
+      if (abbr.size() == 12) {                     // UTC+99:99:99
+        abbr.erase(9, 1);                          // UTC+99:9999
+        abbr.erase(6, 1);                          // UTC+999999
+        if (abbr[8] == '0' && abbr[9] == '0') {    // UTC+999900
+          abbr.erase(8, 2);                        // UTC+9999
+          if (abbr[6] == '0' && abbr[7] == '0') {  // UTC+9900
+            abbr.erase(6, 2);                      // UTC+99
+            if (abbr[4] == '0') {                  // UTC+09
+              abbr.erase(4, 1);                    // UTC+9
+            }
+          }
+        }
+      }
+    }
+  }
+  return abbr;
+}
+
+}  // namespace cctz
+}  // namespace time_internal
+}  // namespace absl

absl/time/internal/cctz/src/time_zone_fixed.h

+// 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.
+
+#ifndef ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_FIXED_H_
+#define ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_FIXED_H_
+
+#include <string>
+
+#include "absl/time/internal/cctz/include/cctz/time_zone.h"
+
+namespace absl {
+namespace time_internal {
+namespace cctz {
+
+// Helper functions for dealing with the names and abbreviations
+// of time zones that are a fixed offset (seconds east) from UTC.
+// FixedOffsetFromName() extracts the offset from a valid fixed-offset
+// name, while FixedOffsetToName() and FixedOffsetToAbbr() generate
+// the canonical zone name and abbreviation respectively for the given
+// offset.
+//
+// A fixed-offset name looks like "Fixed/UTC<+-><hours>:<mins>:<secs>".
+// Its abbreviation is of the form "UTC(<+->H?H(MM(SS)?)?)?" where the
+// optional pieces are omitted when their values are zero.  (Note that
+// the sign is the opposite of that used in a POSIX TZ specification.)
+//
+// Note: FixedOffsetFromName() fails on syntax errors or when the parsed
+// offset exceeds 24 hours.  FixedOffsetToName() and FixedOffsetToAbbr()
+// both produce "UTC" when the argument offset exceeds 24 hours.
+bool FixedOffsetFromName(const std::string& name, sys_seconds* offset);
+std::string FixedOffsetToName(const sys_seconds& offset);
+std::string FixedOffsetToAbbr(const sys_seconds& offset);
+
+}  // namespace cctz
+}  // namespace time_internal
+}  // namespace absl
+
+#endif  // ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_FIXED_H_

absl/time/internal/cctz/src/time_zone_if.cc

+// 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 "time_zone_if.h"
+#include "time_zone_info.h"
+#include "time_zone_libc.h"
+
+namespace absl {
+namespace time_internal {
+namespace cctz {
+
+std::unique_ptr<TimeZoneIf> TimeZoneIf::Load(const std::string& name) {
+  // Support "libc:localtime" and "libc:*" to access the legacy
+  // localtime and UTC support respectively from the C library.
+  if (name.compare(0, 5, "libc:") == 0) {
+    return std::unique_ptr<TimeZoneIf>(new TimeZoneLibC(name.substr(5)));
+  }
+
+  // Otherwise use the "zoneinfo" implementation by default.
+  std::unique_ptr<TimeZoneInfo> tz(new TimeZoneInfo);
+  if (!tz->Load(name)) tz.reset();
+  return std::unique_ptr<TimeZoneIf>(tz.release());
+}
+
+// Defined out-of-line to avoid emitting a weak vtable in all TUs.
+TimeZoneIf::~TimeZoneIf() {}
+
+}  // namespace cctz
+}  // namespace time_internal
+}  // namespace absl

absl/time/internal/cctz/src/time_zone_if.h

+// 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.
+
+#ifndef ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_IF_H_
+#define ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_IF_H_
+
+#include <chrono>
+#include <cstdint>
+#include <memory>
+#include <string>
+
+#include "absl/time/internal/cctz/include/cctz/civil_time.h"
+#include "absl/time/internal/cctz/include/cctz/time_zone.h"
+
+namespace absl {
+namespace time_internal {
+namespace cctz {
+
+// A simple interface used to hide time-zone complexities from time_zone::Impl.
+// Subclasses implement the functions for civil-time conversions in the zone.
+class TimeZoneIf {
+ public:
+  // A factory function for TimeZoneIf implementations.
+  static std::unique_ptr<TimeZoneIf> Load(const std::string& name);
+
+  virtual ~TimeZoneIf();
+
+  virtual time_zone::absolute_lookup BreakTime(
+      const time_point<sys_seconds>& tp) const = 0;
+  virtual time_zone::civil_lookup MakeTime(
+      const civil_second& cs) const = 0;
+
+  virtual std::string Description() const = 0;
+  virtual bool NextTransition(time_point<sys_seconds>* tp) const = 0;
+  virtual bool PrevTransition(time_point<sys_seconds>* tp) const = 0;
+
+ protected:
+  TimeZoneIf() {}
+};
+
+// Convert between time_point<sys_seconds> and a count of seconds since
+// the Unix epoch.  We assume that the std::chrono::system_clock and the
+// Unix clock are second aligned, but not that they share an epoch.
+inline std::int_fast64_t ToUnixSeconds(const time_point<sys_seconds>& tp) {
+  return (tp - std::chrono::time_point_cast<sys_seconds>(
+                   std::chrono::system_clock::from_time_t(0)))
+      .count();
+}
+inline time_point<sys_seconds> FromUnixSeconds(std::int_fast64_t t) {
+  return std::chrono::time_point_cast<sys_seconds>(
+             std::chrono::system_clock::from_time_t(0)) +
+         sys_seconds(t);
+}
+
+}  // namespace cctz
+}  // namespace time_internal
+}  // namespace absl
+
+#endif  // ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_IF_H_

absl/time/internal/cctz/src/time_zone_impl.cc

+// 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 "time_zone_impl.h"
+
+#include <mutex>
+#include <string>
+#include <unordered_map>
+#include <utility>
+
+#include "time_zone_fixed.h"
+
+namespace absl {
+namespace time_internal {
+namespace cctz {
+
+namespace {
+
+// time_zone::Impls are linked into a map to support fast lookup by name.
+using TimeZoneImplByName =
+    std::unordered_map<std::string, const time_zone::Impl*>;
+TimeZoneImplByName* time_zone_map = nullptr;
+
+// Mutual exclusion for time_zone_map.
+std::mutex time_zone_mutex;
+
+}  // namespace
+
+time_zone time_zone::Impl::UTC() {
+  return time_zone(UTCImpl());
+}
+
+bool time_zone::Impl::LoadTimeZone(const std::string& name, time_zone* tz) {
+  const time_zone::Impl* const utc_impl = UTCImpl();
+
+  // First check for UTC (which is never a key in time_zone_map).
+  auto offset = sys_seconds::zero();
+  if (FixedOffsetFromName(name, &offset) && offset == sys_seconds::zero()) {
+    *tz = time_zone(utc_impl);
+    return true;
+  }
+
+  // Then check, under a shared lock, whether the time zone has already
+  // been loaded. This is the common path. TODO: Move to shared_mutex.
+  {
+    std::lock_guard<std::mutex> lock(time_zone_mutex);
+    if (time_zone_map != nullptr) {
+      TimeZoneImplByName::const_iterator itr = time_zone_map->find(name);
+      if (itr != time_zone_map->end()) {
+        *tz = time_zone(itr->second);
+        return itr->second != utc_impl;
+      }
+    }
+  }
+
+  // Now check again, under an exclusive lock.
+  std::lock_guard<std::mutex> lock(time_zone_mutex);
+  if (time_zone_map == nullptr) time_zone_map = new TimeZoneImplByName;
+  const Impl*& impl = (*time_zone_map)[name];
+  if (impl == nullptr) {
+    // The first thread in loads the new time zone.
+    Impl* new_impl = new Impl(name);
+    new_impl->zone_ = TimeZoneIf::Load(new_impl->name_);
+    if (new_impl->zone_ == nullptr) {
+      delete new_impl;  // free the nascent Impl
+      impl = utc_impl;  // and fallback to UTC
+    } else {
+      impl = new_impl;  // install new time zone
+    }
+  }
+  *tz = time_zone(impl);
+  return impl != utc_impl;
+}
+
+const time_zone::Impl& time_zone::Impl::get(const time_zone& tz) {
+  if (tz.impl_ == nullptr) {
+    // Dereferencing an implicit-UTC time_zone is expected to be
+    // rare, so we don't mind paying a small synchronization cost.
+    return *UTCImpl();
+  }
+  return *tz.impl_;
+}
+
+void time_zone::Impl::ClearTimeZoneMapTestOnly() {
+  std::lock_guard<std::mutex> lock(time_zone_mutex);
+  if (time_zone_map != nullptr) {
+    // Existing time_zone::Impl* entries are in the wild, so we simply
+    // leak them.  Future requests will result in reloading the data.
+    time_zone_map->clear();
+  }
+}
+
+time_zone::Impl::Impl(const std::string& name) : name_(name) {}
+
+const time_zone::Impl* time_zone::Impl::UTCImpl() {
+  static Impl* utc_impl = [] {
+    Impl* impl = new Impl("UTC");
+    impl->zone_ = TimeZoneIf::Load(impl->name_);  // never fails
+    return impl;
+  }();
+  return utc_impl;
+}
+
+}  // namespace cctz
+}  // namespace time_internal
+}  // namespace absl

absl/time/internal/cctz/src/time_zone_impl.h

+// 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.
+
+#ifndef ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_IMPL_H_
+#define ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_IMPL_H_
+
+#include <memory>
+#include <string>
+
+#include "absl/time/internal/cctz/include/cctz/civil_time.h"
+#include "absl/time/internal/cctz/include/cctz/time_zone.h"
+#include "time_zone_if.h"
+#include "time_zone_info.h"
+
+namespace absl {
+namespace time_internal {
+namespace cctz {
+
+// time_zone::Impl is the internal object referenced by a cctz::time_zone.
+class time_zone::Impl {
+ public:
+  // The UTC time zone. Also used for other time zones that fail to load.
+  static time_zone UTC();
+
+  // Load a named time zone. Returns false if the name is invalid, or if
+  // some other kind of error occurs. Note that loading "UTC" never fails.
+  static bool LoadTimeZone(const std::string& name, time_zone* tz);
+
+  // Dereferences the time_zone to obtain its Impl.
+  static const time_zone::Impl& get(const time_zone& tz);
+
+  // Clears the map of cached time zones.  Primarily for use in benchmarks
+  // that gauge the performance of loading/parsing the time-zone data.
+  static void ClearTimeZoneMapTestOnly();
+
+  // The primary key is the time-zone ID (e.g., "America/New_York").
+  const std::string& name() const { return name_; }
+
+  // Breaks a time_point down to civil-time components in this time zone.
+  time_zone::absolute_lookup BreakTime(
+      const time_point<sys_seconds>& tp) const {
+    return zone_->BreakTime(tp);
+  }
+
+  // Converts the civil-time components in this time zone into a time_point.
+  // That is, the opposite of BreakTime(). The requested civil time may be
+  // ambiguous or illegal due to a change of UTC offset.
+  time_zone::civil_lookup MakeTime(const civil_second& cs) const {
+    return zone_->MakeTime(cs);
+  }
+
+  // Returns an implementation-specific description of this time zone.
+  std::string Description() const { return zone_->Description(); }
+
+  // Finds the time of the next/previous offset change in this time zone.
+  //
+  // By definition, NextTransition(&tp) returns false when tp has its
+  // maximum value, and PrevTransition(&tp) returns false when tp has its
+  // mimimum value.  If the zone has no transitions, the result will also
+  // be false no matter what the argument.
+  //
+  // Otherwise, when tp has its mimimum value, NextTransition(&tp) returns
+  // true and sets tp to the first recorded transition.  Chains of calls
+  // to NextTransition()/PrevTransition() will eventually return false,
+  // but it is unspecified exactly when NextTransition(&tp) jumps to false,
+  // or what time is set by PrevTransition(&tp) for a very distant tp.
+  bool NextTransition(time_point<sys_seconds>* tp) const {
+    return zone_->NextTransition(tp);
+  }
+  bool PrevTransition(time_point<sys_seconds>* tp) const {
+    return zone_->PrevTransition(tp);
+  }
+
+ private:
+  explicit Impl(const std::string& name);
+  static const Impl* UTCImpl();
+
+  const std::string name_;
+  std::unique_ptr<TimeZoneIf> zone_;
+};
+
+}  // namespace cctz
+}  // namespace time_internal
+}  // namespace absl
+
+#endif  // ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_IMPL_H_

absl/time/internal/cctz/src/time_zone_info.h

+// 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.
+
+#ifndef ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_INFO_H_
+#define ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_INFO_H_
+
+#include <atomic>
+#include <cstddef>
+#include <cstdint>
+#include <string>
+#include <vector>
+
+#include "absl/time/internal/cctz/include/cctz/civil_time.h"
+#include "absl/time/internal/cctz/include/cctz/time_zone.h"
+#include "absl/time/internal/cctz/include/cctz/zone_info_source.h"
+#include "time_zone_if.h"
+#include "tzfile.h"
+
+namespace absl {
+namespace time_internal {
+namespace cctz {
+
+// A transition to a new UTC offset.
+struct Transition {
+  std::int_least64_t unix_time;   // the instant of this transition
+  std::uint_least8_t type_index;  // index of the transition type
+  civil_second civil_sec;         // local civil time of transition
+  civil_second prev_civil_sec;    // local civil time one second earlier
+
+  struct ByUnixTime {
+    inline bool operator()(const Transition& lhs, const Transition& rhs) const {
+      return lhs.unix_time < rhs.unix_time;
+    }
+  };
+  struct ByCivilTime {
+    inline bool operator()(const Transition& lhs, const Transition& rhs) const {
+      return lhs.civil_sec < rhs.civil_sec;
+    }
+  };
+};
+
+// The characteristics of a particular transition.
+struct TransitionType {
+  std::int_least32_t utc_offset;  // the new prevailing UTC offset
+  civil_second civil_max;         // max convertible civil time for offset
+  civil_second civil_min;         // min convertible civil time for offset
+  bool is_dst;                    // did we move into daylight-saving time
+  std::uint_least8_t abbr_index;  // index of the new abbreviation
+};
+
+// A time zone backed by the IANA Time Zone Database (zoneinfo).
+class TimeZoneInfo : public TimeZoneIf {
+ public:
+  TimeZoneInfo() = default;
+  TimeZoneInfo(const TimeZoneInfo&) = delete;
+  TimeZoneInfo& operator=(const TimeZoneInfo&) = delete;
+
+  // Loads the zoneinfo for the given name, returning true if successful.
+  bool Load(const std::string& name);
+
+  // TimeZoneIf implementations.
+  time_zone::absolute_lookup BreakTime(
+      const time_point<sys_seconds>& tp) const override;
+  time_zone::civil_lookup MakeTime(
+      const civil_second& cs) const override;
+  std::string Description() const override;
+  bool NextTransition(time_point<sys_seconds>* tp) const override;
+  bool PrevTransition(time_point<sys_seconds>* tp) const override;
+
+ private:
+  struct Header {  // counts of:
+    std::size_t timecnt;     // transition times
+    std::size_t typecnt;     // transition types
+    std::size_t charcnt;     // zone abbreviation characters
+    std::size_t leapcnt;     // leap seconds (we expect none)
+    std::size_t ttisstdcnt;  // UTC/local indicators (unused)
+    std::size_t ttisgmtcnt;  // standard/wall indicators (unused)
+
+    bool Build(const tzhead& tzh);
+    std::size_t DataLength(std::size_t time_len) const;
+  };
+
+  void CheckTransition(const std::string& name, const TransitionType& tt,
+                       std::int_fast32_t offset, bool is_dst,
+                       const std::string& abbr) const;
+  bool EquivTransitions(std::uint_fast8_t tt1_index,
+                        std::uint_fast8_t tt2_index) const;
+  void ExtendTransitions(const std::string& name, const Header& hdr);
+
+  bool ResetToBuiltinUTC(const sys_seconds& offset);
+  bool Load(const std::string& name, ZoneInfoSource* zip);
+
+  // Helpers for BreakTime() and MakeTime().
+  time_zone::absolute_lookup LocalTime(std::int_fast64_t unix_time,
+                                       const TransitionType& tt) const;
+  time_zone::absolute_lookup LocalTime(std::int_fast64_t unix_time,
+                                       const Transition& tr) const;
+  time_zone::civil_lookup TimeLocal(const civil_second& cs,
+                                    year_t c4_shift) const;
+
+  std::vector<Transition> transitions_;  // ordered by unix_time and civil_sec
+  std::vector<TransitionType> transition_types_;  // distinct transition types
+  std::uint_fast8_t default_transition_type_;  // for before first transition
+  std::string abbreviations_;  // all the NUL-terminated abbreviations
+
+  std::string future_spec_;  // for after the last zic transition
+  bool extended_;            // future_spec_ was used to generate transitions
+  year_t last_year_;         // the final year of the generated transitions
+
+  // We remember the transitions found during the last BreakTime() and
+  // MakeTime() calls. If the next request is for the same transition we
+  // will avoid re-searching.
+  mutable std::atomic<std::size_t> local_time_hint_ = {};  // BreakTime() hint
+  mutable std::atomic<std::size_t> time_local_hint_ = {};  // MakeTime() hint
+};
+
+}  // namespace cctz
+}  // namespace time_internal
+}  // namespace absl
+
+#endif  // ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_INFO_H_

absl/time/internal/cctz/src/time_zone_libc.cc

+// 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.
+
+#if defined(_WIN32) || defined(_WIN64)
+#define _CRT_SECURE_NO_WARNINGS 1
+#endif
+
+#include "time_zone_libc.h"
+
+#include <chrono>
+#include <ctime>
+#include <tuple>
+#include <utility>
+
+#include "absl/time/internal/cctz/include/cctz/civil_time.h"
+#include "absl/time/internal/cctz/include/cctz/time_zone.h"
+
+namespace absl {
+namespace time_internal {
+namespace cctz {
+
+namespace {
+
+// .first is seconds east of UTC; .second is the time-zone abbreviation.
+using OffsetAbbr = std::pair<int, const char*>;
+
+// Defines a function that can be called as follows:
+//
+//   std::tm tm = ...;
+//   OffsetAbbr off_abbr = get_offset_abbr(tm);
+//
+#if defined(_WIN32) || defined(_WIN64)
+// Uses the globals: '_timezone', '_dstbias' and '_tzname'.
+OffsetAbbr get_offset_abbr(const std::tm& tm) {
+  const bool is_dst = tm.tm_isdst > 0;
+  const int off = _timezone + (is_dst ? _dstbias : 0);
+  const char* abbr = _tzname[is_dst];
+  return {off, abbr};
+}
+#elif defined(__sun)
+// Uses the globals: 'timezone', 'altzone' and 'tzname'.
+OffsetAbbr get_offset_abbr(const std::tm& tm) {
+  const bool is_dst = tm.tm_isdst > 0;
+  const int off = is_dst ? altzone : timezone;
+  const char* abbr = tzname[is_dst];
+  return {off, abbr};
+}
+#elif defined(__native_client__) || defined(__myriad2__) || \
+    defined(__EMSCRIPTEN__)
+// Uses the globals: 'timezone' and 'tzname'.
+OffsetAbbr get_offset_abbr(const std::tm& tm) {
+  const bool is_dst = tm.tm_isdst > 0;
+  const int off = _timezone + (is_dst ? 60 * 60 : 0);
+  const char* abbr = tzname[is_dst];
+  return {off, abbr};
+}
+#else
+//
+// Returns an OffsetAbbr using std::tm fields with various spellings.
+//
+#if !defined(tm_gmtoff) && !defined(tm_zone)
+template <typename T>
+OffsetAbbr get_offset_abbr(const T& tm, decltype(&T::tm_gmtoff) = nullptr,
+                           decltype(&T::tm_zone) = nullptr) {
+  return {tm.tm_gmtoff, tm.tm_zone};
+}
+#endif  // !defined(tm_gmtoff) && !defined(tm_zone)
+#if !defined(__tm_gmtoff) && !defined(__tm_zone)
+template <typename T>
+OffsetAbbr get_offset_abbr(const T& tm, decltype(&T::__tm_gmtoff) = nullptr,
+                           decltype(&T::__tm_zone) = nullptr) {
+  return {tm.__tm_gmtoff, tm.__tm_zone};
+}
+#endif  // !defined(__tm_gmtoff) && !defined(__tm_zone)
+#endif
+
+}  // namespace
+
+TimeZoneLibC::TimeZoneLibC(const std::string& name)
+    : local_(name == "localtime") {}
+
+time_zone::absolute_lookup TimeZoneLibC::BreakTime(
+    const time_point<sys_seconds>& tp) const {
+  time_zone::absolute_lookup al;
+  std::time_t t = ToUnixSeconds(tp);
+  std::tm tm;
+  if (local_) {
+#if defined(_WIN32) || defined(_WIN64)
+    localtime_s(&tm, &t);
+#else
+    localtime_r(&t, &tm);
+#endif
+    std::tie(al.offset, al.abbr) = get_offset_abbr(tm);
+  } else {
+#if defined(_WIN32) || defined(_WIN64)
+    gmtime_s(&tm, &t);
+#else
+    gmtime_r(&t, &tm);
+#endif
+    al.offset = 0;
+    al.abbr = "UTC";
+  }
+  al.cs = civil_second(tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
+                       tm.tm_hour, tm.tm_min, tm.tm_sec);
+  al.is_dst = tm.tm_isdst > 0;
+  return al;
+}
+
+time_zone::civil_lookup TimeZoneLibC::MakeTime(const civil_second& cs) const {
+  time_zone::civil_lookup cl;
+  std::time_t t;
+  if (local_) {
+    // Does not handle SKIPPED/AMBIGUOUS or huge years.
+    std::tm tm;
+    tm.tm_year = static_cast<int>(cs.year() - 1900);
+    tm.tm_mon = cs.month() - 1;
+    tm.tm_mday = cs.day();
+    tm.tm_hour = cs.hour();
+    tm.tm_min = cs.minute();
+    tm.tm_sec = cs.second();
+    tm.tm_isdst = -1;
+    t = std::mktime(&tm);
+  } else {
+    t = cs - civil_second();
+  }
+  cl.kind = time_zone::civil_lookup::UNIQUE;
+  cl.pre = cl.trans = cl.post = FromUnixSeconds(t);
+  return cl;
+}
+
+std::string TimeZoneLibC::Description() const {
+  return local_ ? "localtime" : "UTC";
+}
+
+bool TimeZoneLibC::NextTransition(time_point<sys_seconds>* tp) const {
+  return false;
+}
+
+bool TimeZoneLibC::PrevTransition(time_point<sys_seconds>* tp) const {
+  return false;
+}
+
+}  // namespace cctz
+}  // namespace time_internal
+}  // namespace absl

absl/time/internal/cctz/src/time_zone_libc.h

+// 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.
+
+#ifndef ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_LIBC_H_
+#define ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_LIBC_H_
+
+#include <string>
+
+#include "time_zone_if.h"
+
+namespace absl {
+namespace time_internal {
+namespace cctz {
+
+// A time zone backed by gmtime_r(3), localtime_r(3), and mktime(3),
+// and which therefore only supports UTC and the local time zone.
+// TODO: Add support for fixed offsets from UTC.
+class TimeZoneLibC : public TimeZoneIf {
+ public:
+  explicit TimeZoneLibC(const std::string& name);
+
+  // TimeZoneIf implementations.
+  time_zone::absolute_lookup BreakTime(
+      const time_point<sys_seconds>& tp) const override;
+  time_zone::civil_lookup MakeTime(
+      const civil_second& cs) const override;
+  std::string Description() const override;
+  bool NextTransition(time_point<sys_seconds>* tp) const override;
+  bool PrevTransition(time_point<sys_seconds>* tp) const override;
+
+ private:
+  const bool local_;  // localtime or UTC
+};
+
+}  // namespace cctz
+}  // namespace time_internal
+}  // namespace absl
+
+#endif  // ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_LIBC_H_

absl/time/internal/cctz/src/time_zone_lookup.cc

+// 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"
+
+#if defined(__ANDROID__)
+#include <sys/system_properties.h>
+#if __ANDROID_API__ >= 21
+#include <dlfcn.h>
+#endif
+#endif
+#include <cstdlib>
+#include <cstring>
+#include <string>
+
+#include "time_zone_fixed.h"
+#include "time_zone_impl.h"
+
+namespace absl {
+namespace time_internal {
+namespace cctz {
+
+#if defined(__ANDROID__) && __ANDROID_API__ >= 21
+namespace {
+// Android 'L' removes __system_property_get() from the NDK, however
+// it is still a hidden symbol in libc so we use dlsym() to access it.
+// See Chromium's base/sys_info_android.cc for a similar example.
+
+using property_get_func = int (*)(const char*, char*);
+
+property_get_func LoadSystemPropertyGet() {
+  int flag = RTLD_LAZY | RTLD_GLOBAL;
+#if defined(RTLD_NOLOAD)
+  flag |= RTLD_NOLOAD;  // libc.so should already be resident
+#endif
+  if (void* handle = dlopen("libc.so", flag)) {
+    void* sym = dlsym(handle, "__system_property_get");
+    dlclose(handle);
+    return reinterpret_cast<property_get_func>(sym);
+  }
+  return nullptr;
+}
+
+int __system_property_get(const char* name, char* value) {
+  static property_get_func system_property_get = LoadSystemPropertyGet();
+  return system_property_get ? system_property_get(name, value) : -1;
+}
+
+}  // namespace
+#endif
+
+std::string time_zone::name() const {
+  return time_zone::Impl::get(*this).name();
+}
+
+time_zone::absolute_lookup time_zone::lookup(
+    const time_point<sys_seconds>& tp) const {
+  return time_zone::Impl::get(*this).BreakTime(tp);
+}
+
+time_zone::civil_lookup time_zone::lookup(const civil_second& cs) const {
+  return time_zone::Impl::get(*this).MakeTime(cs);
+}
+
+bool operator==(time_zone lhs, time_zone rhs) {
+  return &time_zone::Impl::get(lhs) == &time_zone::Impl::get(rhs);
+}
+
+bool load_time_zone(const std::string& name, time_zone* tz) {
+  return time_zone::Impl::LoadTimeZone(name, tz);
+}
+
+time_zone utc_time_zone() {
+  return time_zone::Impl::UTC();  // avoid name lookup
+}
+
+time_zone fixed_time_zone(const sys_seconds& offset) {
+  time_zone tz;
+  load_time_zone(FixedOffsetToName(offset), &tz);
+  return tz;
+}
+
+time_zone local_time_zone() {
+  const char* zone = ":localtime";
+
+  // Allow ${TZ} to override to default zone.
+  char* tz_env = nullptr;
+#if defined(_MSC_VER)
+  _dupenv_s(&tz_env, nullptr, "TZ");
+#else
+  tz_env = std::getenv("TZ");
+#endif
+#if defined(__ANDROID__)
+  char sysprop[PROP_VALUE_MAX];
+  if (tz_env == nullptr)
+    if (__system_property_get("persist.sys.timezone", sysprop) > 0)
+      tz_env = sysprop;
+#endif
+  if (tz_env) zone = tz_env;
+
+  // We only support the "[:]<zone-name>" form.
+  if (*zone == ':') ++zone;
+
+  // Map "localtime" to a system-specific name, but
+  // allow ${LOCALTIME} to override the default name.
+  char* localtime_env = nullptr;
+  if (strcmp(zone, "localtime") == 0) {
+#if defined(_MSC_VER)
+    // System-specific default is just "localtime".
+    _dupenv_s(&localtime_env, nullptr, "LOCALTIME");
+#else
+    zone = "/etc/localtime";  // System-specific default.
+    localtime_env = std::getenv("LOCALTIME");
+#endif
+    if (localtime_env) zone = localtime_env;
+  }
+
+  const std::string name = zone;
+#if defined(_MSC_VER)
+  free(localtime_env);
+  free(tz_env);
+#endif
+
+  time_zone tz;
+  load_time_zone(name, &tz);  // Falls back to UTC.
+  return tz;
+}
+
+}  // namespace cctz
+}  // namespace time_internal
+}  // namespace absl

absl/time/internal/cctz/src/time_zone_posix.cc

+// 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 "time_zone_posix.h"
+
+#include <cstddef>
+#include <cstring>
+#include <limits>
+#include <string>
+
+namespace absl {
+namespace time_internal {
+namespace cctz {
+
+namespace {
+
+const char kDigits[] = "0123456789";
+
+const char* ParseInt(const char* p, int min, int max, int* vp) {
+  int value = 0;
+  const char* op = p;
+  const int kMaxInt = std::numeric_limits<int>::max();
+  for (; const char* dp = strchr(kDigits, *p); ++p) {
+    int d = static_cast<int>(dp - kDigits);
+    if (d >= 10) break;  // '\0'
+    if (value > kMaxInt / 10) return nullptr;
+    value *= 10;
+    if (value > kMaxInt - d) return nullptr;
+    value += d;
+  }
+  if (p == op || value < min || value > max) return nullptr;
+  *vp = value;
+  return p;
+}
+
+// abbr = <.*?> | [^-+,\d]{3,}
+const char* ParseAbbr(const char* p, std::string* abbr) {
+  const char* op = p;
+  if (*p == '<') {  // special zoneinfo <...> form
+    while (*++p != '>') {
+      if (*p == '\0') return nullptr;
+    }
+    abbr->assign(op + 1, static_cast<std::size_t>(p - op) - 1);
+    return ++p;
+  }
+  while (*p != '\0') {
+    if (strchr("-+,", *p)) break;
+    if (strchr(kDigits, *p)) break;
+    ++p;
+  }
+  if (p - op < 3) return nullptr;
+  abbr->assign(op, static_cast<std::size_t>(p - op));
+  return p;
+}
+
+// offset = [+|-]hh[:mm[:ss]] (aggregated into single seconds value)
+const char* ParseOffset(const char* p, int min_hour, int max_hour, int sign,
+                        std::int_fast32_t* offset) {
+  if (p == nullptr) return nullptr;
+  if (*p == '+' || *p == '-') {
+    if (*p++ == '-') sign = -sign;
+  }
+  int hours = 0;
+  int minutes = 0;
+  int seconds = 0;
+
+  p = ParseInt(p, min_hour, max_hour, &hours);
+  if (p == nullptr) return nullptr;
+  if (*p == ':') {
+    p = ParseInt(p + 1, 0, 59, &minutes);
+    if (p == nullptr) return nullptr;
+    if (*p == ':') {
+      p = ParseInt(p + 1, 0, 59, &seconds);
+      if (p == nullptr) return nullptr;
+    }
+  }
+  *offset = sign * ((((hours * 60) + minutes) * 60) + seconds);
+  return p;
+}
+
+// datetime = ( Jn | n | Mm.w.d ) [ / offset ]
+const char* ParseDateTime(const char* p, PosixTransition* res) {
+  if (p != nullptr && *p == ',') {
+    if (*++p == 'M') {
+      int month = 0;
+      if ((p = ParseInt(p + 1, 1, 12, &month)) != nullptr && *p == '.') {
+        int week = 0;
+        if ((p = ParseInt(p + 1, 1, 5, &week)) != nullptr && *p == '.') {
+          int weekday = 0;
+          if ((p = ParseInt(p + 1, 0, 6, &weekday)) != nullptr) {
+            res->date.fmt = PosixTransition::M;
+            res->date.m.month = static_cast<int_fast8_t>(month);
+            res->date.m.week = static_cast<int_fast8_t>(week);
+            res->date.m.weekday = static_cast<int_fast8_t>(weekday);
+          }
+        }
+      }
+    } else if (*p == 'J') {
+      int day = 0;
+      if ((p = ParseInt(p + 1, 1, 365, &day)) != nullptr) {
+        res->date.fmt = PosixTransition::J;
+        res->date.j.day = static_cast<int_fast16_t>(day);
+      }
+    } else {
+      int day = 0;
+      if ((p = ParseInt(p, 0, 365, &day)) != nullptr) {
+        res->date.fmt = PosixTransition::N;
+        res->date.j.day = static_cast<int_fast16_t>(day);
+      }
+    }
+  }
+  if (p != nullptr) {
+    res->time.offset = 2 * 60 * 60;  // default offset is 02:00:00
+    if (*p == '/') p = ParseOffset(p + 1, -167, 167, 1, &res->time.offset);
+  }
+  return p;
+}
+
+}  // namespace
+
+// spec = std offset [ dst [ offset ] , datetime , datetime ]
+bool ParsePosixSpec(const std::string& spec, PosixTimeZone* res) {
+  const char* p = spec.c_str();
+  if (*p == ':') return false;
+
+  p = ParseAbbr(p, &res->std_abbr);
+  p = ParseOffset(p, 0, 24, -1, &res->std_offset);
+  if (p == nullptr) return false;
+  if (*p == '\0') return true;
+
+  p = ParseAbbr(p, &res->dst_abbr);
+  if (p == nullptr) return false;
+  res->dst_offset = res->std_offset + (60 * 60);  // default
+  if (*p != ',') p = ParseOffset(p, 0, 24, -1, &res->dst_offset);
+
+  p = ParseDateTime(p, &res->dst_start);
+  p = ParseDateTime(p, &res->dst_end);
+
+  return p != nullptr && *p == '\0';
+}
+
+}  // namespace cctz
+}  // namespace time_internal
+}  // namespace absl

absl/time/internal/cctz/src/time_zone_posix.h

+// 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.
+
+// Parsing of a POSIX zone spec as described in the TZ part of section 8.3 in
+// http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap08.html.
+//
+// The current POSIX spec for America/Los_Angeles is "PST8PDT,M3.2.0,M11.1.0",
+// which would be broken down as ...
+//
+//   PosixTimeZone {
+//     std_abbr = "PST"
+//     std_offset = -28800
+//     dst_abbr = "PDT"
+//     dst_offset = -25200
+//     dst_start = PosixTransition {
+//       date {
+//         m {
+//           month = 3
+//           week = 2
+//           weekday = 0
+//         }
+//       }
+//       time {
+//         offset = 7200
+//       }
+//     }
+//     dst_end = PosixTransition {
+//       date {
+//         m {
+//           month = 11
+//           week = 1
+//           weekday = 0
+//         }
+//       }
+//       time {
+//         offset = 7200
+//       }
+//     }
+//   }
+
+#ifndef ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_POSIX_H_
+#define ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_POSIX_H_
+
+#include <cstdint>
+#include <string>
+
+namespace absl {
+namespace time_internal {
+namespace cctz {
+
+// The date/time of the transition. The date is specified as either:
+// (J) the Nth day of the year (1 <= N <= 365), excluding leap days, or
+// (N) the Nth day of the year (0 <= N <= 365), including leap days, or
+// (M) the Nth weekday of a month (e.g., the 2nd Sunday in March).
+// The time, specified as a day offset, identifies the particular moment
+// of the transition, and may be negative or >= 24h, and in which case
+// it would take us to another day, and perhaps week, or even month.
+struct PosixTransition {
+  enum DateFormat { J, N, M };
+  struct {
+    DateFormat fmt;
+    union {
+      struct {
+        std::int_fast16_t day;  // day of non-leap year [1:365]
+      } j;
+      struct {
+        std::int_fast16_t day;  // day of year [0:365]
+      } n;
+      struct {
+        std::int_fast8_t month;    // month of year [1:12]
+        std::int_fast8_t week;     // week of month [1:5] (5==last)
+        std::int_fast8_t weekday;  // 0==Sun, ..., 6=Sat
+      } m;
+    };
+  } date;
+  struct {
+    std::int_fast32_t offset;  // seconds before/after 00:00:00
+  } time;
+};
+
+// The entirety of a POSIX-std::string specified time-zone rule. The standard
+// abbreviation and offset are always given. If the time zone includes
+// daylight saving, then the daylight abbrevation is non-empty and the
+// remaining fields are also valid. Note that the start/end transitions
+// are not ordered---in the southern hemisphere the transition to end
+// daylight time occurs first in any particular year.
+struct PosixTimeZone {
+  std::string std_abbr;
+  std::int_fast32_t std_offset;
+
+  std::string dst_abbr;
+  std::int_fast32_t dst_offset;
+  PosixTransition dst_start;
+  PosixTransition dst_end;
+};
+
+// Breaks down a POSIX time-zone specification into its constituent pieces,
+// filling in any missing values (DST offset, or start/end transition times)
+// with the standard-defined defaults. Returns false if the specification
+// could not be parsed (although some fields of *res may have been altered).
+bool ParsePosixSpec(const std::string& spec, PosixTimeZone* res);
+
+}  // namespace cctz
+}  // namespace time_internal
+}  // namespace absl
+
+#endif  // ABSL_TIME_INTERNAL_CCTZ_TIME_ZONE_POSIX_H_

absl/time/internal/cctz/src/tzfile.h

+#ifndef TZFILE_H
+
+#define TZFILE_H
+
+/*
+** This file is in the public domain, so clarified as of
+** 1996-06-05 by Arthur David Olson.
+*/
+
+/*
+** This header is for use ONLY with the time conversion code.
+** There is no guarantee that it will remain unchanged,
+** or that it will remain at all.
+** Do NOT copy it to any system include directory.
+** Thank you!
+*/
+
+/*
+** Information about time zone files.
+*/
+
+#ifndef TZDIR
+#define TZDIR	"/usr/share/zoneinfo" /* Time zone object file directory */
+#endif /* !defined TZDIR */
+
+#ifndef TZDEFAULT
+#define TZDEFAULT	"/etc/localtime"
+#endif /* !defined TZDEFAULT */
+
+#ifndef TZDEFRULES
+#define TZDEFRULES	"posixrules"
+#endif /* !defined TZDEFRULES */
+
+/*
+** Each file begins with. . .
+*/
+
+#define	TZ_MAGIC	"TZif"
+
+struct tzhead {
+	char	tzh_magic[4];		/* TZ_MAGIC */
+	char	tzh_version[1];		/* '\0' or '2' or '3' as of 2013 */
+	char	tzh_reserved[15];	/* reserved; must be zero */
+	char	tzh_ttisgmtcnt[4];	/* coded number of trans. time flags */
+	char	tzh_ttisstdcnt[4];	/* coded number of trans. time flags */
+	char	tzh_leapcnt[4];		/* coded number of leap seconds */
+	char	tzh_timecnt[4];		/* coded number of transition times */
+	char	tzh_typecnt[4];		/* coded number of local time types */
+	char	tzh_charcnt[4];		/* coded number of abbr. chars */
+};
+
+/*
+** . . .followed by. . .
+**
+**	tzh_timecnt (char [4])s		coded transition times a la time(2)
+**	tzh_timecnt (unsigned char)s	types of local time starting at above
+**	tzh_typecnt repetitions of
+**		one (char [4])		coded UT offset in seconds
+**		one (unsigned char)	used to set tm_isdst
+**		one (unsigned char)	that's an abbreviation list index
+**	tzh_charcnt (char)s		'\0'-terminated zone abbreviations
+**	tzh_leapcnt repetitions of
+**		one (char [4])		coded leap second transition times
+**		one (char [4])		total correction after above
+**	tzh_ttisstdcnt (char)s		indexed by type; if 1, transition
+**					time is standard time, if 0,
+**					transition time is wall clock time
+**					if absent, transition times are
+**					assumed to be wall clock time
+**	tzh_ttisgmtcnt (char)s		indexed by type; if 1, transition
+**					time is UT, if 0,
+**					transition time is local time
+**					if absent, transition times are
+**					assumed to be local time
+*/
+
+/*
+** If tzh_version is '2' or greater, the above is followed by a second instance
+** of tzhead and a second instance of the data in which each coded transition
+** time uses 8 rather than 4 chars,
+** then a POSIX-TZ-environment-variable-style std::string for use in handling
+** instants after the last transition time stored in the file
+** (with nothing between the newlines if there is no POSIX representation for
+** such instants).
+**
+** If tz_version is '3' or greater, the above is extended as follows.
+** First, the POSIX TZ std::string's hour offset may range from -167
+** through 167 as compared to the POSIX-required 0 through 24.
+** Second, its DST start time may be January 1 at 00:00 and its stop
+** time December 31 at 24:00 plus the difference between DST and
+** standard time, indicating DST all year.
+*/
+
+/*
+** In the current implementation, "tzset()" refuses to deal with files that
+** exceed any of the limits below.
+*/
+
+#ifndef TZ_MAX_TIMES
+#define TZ_MAX_TIMES	2000
+#endif /* !defined TZ_MAX_TIMES */
+
+#ifndef TZ_MAX_TYPES
+/* This must be at least 17 for Europe/Samara and Europe/Vilnius.  */
+#define TZ_MAX_TYPES	256 /* Limited by what (unsigned char)'s can hold */
+#endif /* !defined TZ_MAX_TYPES */
+
+#ifndef TZ_MAX_CHARS
+#define TZ_MAX_CHARS	50	/* Maximum number of abbreviation characters */
+				/* (limited by what unsigned chars can hold) */
+#endif /* !defined TZ_MAX_CHARS */
+
+#ifndef TZ_MAX_LEAPS
+#define TZ_MAX_LEAPS	50	/* Maximum number of leap second corrections */
+#endif /* !defined TZ_MAX_LEAPS */
+
+#endif /* !defined TZFILE_H */

absl/time/internal/cctz/src/zone_info_source.cc

+// 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/zone_info_source.h"
+
+namespace absl {
+namespace time_internal {
+namespace cctz {
+
+// Defined out-of-line to avoid emitting a weak vtable in all TUs.
+ZoneInfoSource::~ZoneInfoSource() {}
+
+}  // namespace cctz
+}  // namespace time_internal
+}  // namespace absl
+
+namespace absl {
+namespace time_internal {
+namespace cctz_extension {
+
+namespace {
+
+// A default for cctz_extension::zone_info_source_factory, which simply
+// defers to the fallback factory.
+std::unique_ptr<absl::time_internal::cctz::ZoneInfoSource> DefaultFactory(
+    const std::string& name,
+    const std::function<std::unique_ptr<absl::time_internal::cctz::ZoneInfoSource>(
+        const std::string& name)>& fallback_factory) {
+  return fallback_factory(name);
+}
+
+}  // namespace
+
+// A "weak" definition for cctz_extension::zone_info_source_factory.
+// The user may override this with their own "strong" definition (see
+// zone_info_source.h).
+#if defined(_MSC_VER)
+extern ZoneInfoSourceFactory zone_info_source_factory;
+extern ZoneInfoSourceFactory default_factory;
+ZoneInfoSourceFactory default_factory = DefaultFactory;
+#if defined(_M_IX86)
+#pragma comment( \
+    linker,      \
+    "/alternatename:?zone_info_source_factory@cctz_extension@time_internal@absl@@3P6A?AV?$unique_ptr@VZoneInfoSource@cctz@time_internal@absl@@U?$default_delete@VZoneInfoSource@cctz@time_internal@absl@@@std@@@std@@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@5@ABV?$function@$$A6A?AV?$unique_ptr@VZoneInfoSource@cctz@time_internal@absl@@U?$default_delete@VZoneInfoSource@cctz@time_internal@absl@@@std@@@std@@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@2@@Z@5@@ZA=?default_factory@cctz_extension@time_internal@absl@@3P6A?AV?$unique_ptr@VZoneInfoSource@cctz@time_internal@absl@@U?$default_delete@VZoneInfoSource@cctz@time_internal@absl@@@std@@@std@@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@5@ABV?$function@$$A6A?AV?$unique_ptr@VZoneInfoSource@cctz@time_internal@absl@@U?$default_delete@VZoneInfoSource@cctz@time_internal@absl@@@std@@@std@@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@2@@Z@5@@ZA")
+#elif defined(_M_IA_64) || defined(_M_AMD64)
+#pragma comment( \
+    linker,      \
+    "/alternatename:?zone_info_source_factory@cctz_extension@time_internal@absl@@3P6A?AV?$unique_ptr@VZoneInfoSource@cctz@time_internal@absl@@U?$default_delete@VZoneInfoSource@cctz@time_internal@absl@@@std@@@std@@AEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@5@AEBV?$function@$$A6A?AV?$unique_ptr@VZoneInfoSource@cctz@time_internal@absl@@U?$default_delete@VZoneInfoSource@cctz@time_internal@absl@@@std@@@std@@AEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@2@@Z@5@@ZEA=?default_factory@cctz_extension@time_internal@absl@@3P6A?AV?$unique_ptr@VZoneInfoSource@cctz@time_internal@absl@@U?$default_delete@VZoneInfoSource@cctz@time_internal@absl@@@std@@@std@@AEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@5@AEBV?$function@$$A6A?AV?$unique_ptr@VZoneInfoSource@cctz@time_internal@absl@@U?$default_delete@VZoneInfoSource@cctz@time_internal@absl@@@std@@@std@@AEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@2@@Z@5@@ZEA")
+#else
+#error Unsupported MSVC platform
+#endif
+#else
+ZoneInfoSourceFactory zone_info_source_factory
+    __attribute__((weak)) = DefaultFactory;
+#endif  // _MSC_VER
+
+}  // namespace cctz_extension
+}  // namespace time_internal
+}  // namespace absl

absl/time/internal/cctz/testdata/README.zoneinfo

+testdata/zoneinfo contains time-zone data files that may be used with CCTZ.
+Install them in a location referenced by the ${TZDIR} environment variable.
+Symbolic and hard links have been eliminated for portability.
+
+On Linux systems the distribution's versions of these files can probably
+already be found in the default ${TZDIR} location, /usr/share/zoneinfo.
+
+New versions can be generated using the following shell script.
+
+  #!/bin/sh -
+  set -e
+  DESTDIR=$(mktemp -d)
+  trap "rm -fr ${DESTDIR}" 0 2 15
+  (
+    cd ${DESTDIR}
+    git clone https://github.com/eggert/tz.git
+    make --directory=tz \
+        install DESTDIR=${DESTDIR} \
+                DATAFORM=vanguard \
+                TZDIR=/zoneinfo \
+                REDO=posix_only \
+                LOCALTIME=Factory \
+                TZDATA_TEXT= \
+                ZONETABLES=zone1970.tab
+    tar --create --dereference --hard-dereference --file tzfile.tar \
+        --directory=tz tzfile.h
+    tar --create --dereference --hard-dereference --file zoneinfo.tar \
+        --exclude=zoneinfo/posixrules zoneinfo \
+        --directory=tz version
+  )
+  tar --extract --directory src --file ${DESTDIR}/tzfile.tar
+  tar --extract --directory testdata --file ${DESTDIR}/zoneinfo.tar
+  exit 0
+
+To run the CCTZ tests using the testdata/zoneinfo files, execute:
+
+  bazel test --test_env=TZDIR=${PWD}/testdata/zoneinfo ...

absl/time/internal/cctz/testdata/version

+2018d-2-g8d1dac0