Export of internal Abseil changes.

--
70f43a482d7d4ae4a255f17ca02b0106653dd600 by Shaindel Schwartz <shaindel@google.com>:

Internal change

PiperOrigin-RevId: 201571193

--
93e6e9c2e683158be49d9dd1f5cb1a91d0c0f556 by Abseil Team <absl-team@google.com>:

Internal change.

PiperOrigin-RevId: 201567108

--
fbd8ee94fbe9f2448e5adf5e88706f9c8216048f by Juemin Yang <jueminyang@google.com>:

str_format release

PiperOrigin-RevId: 201565129

--
387faa301555a8a888c4429df52734aa806dca46 by Abseil Team <absl-team@google.com>:

Adds a defaulted allocator parameter to the size_type constructor of InlinedVector

PiperOrigin-RevId: 201558711

--
39b15ea2c68d7129d70cbde7e71af900032595ec by Matt Calabrese <calabrese@google.com>:

Update the variant implementation to eliminate unnecessary checking on alternative access when the index is known or required to be correct.

PiperOrigin-RevId: 201529535

--
adab77f1f7bb363aa534297f22aae2b0f08889ea by Abseil Team <absl-team@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 201458388

--
a701dc0ba62e3cadf0de14203415b91df4ee8151 by Greg Falcon <gfalcon@google.com>:

Internal cleanup

PiperOrigin-RevId: 201394836

--
8a7191410b8f440fdfa27f722ff05e451502ab61 by Abseil Team <absl-team@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 201369269
GitOrigin-RevId: 70f43a482d7d4ae4a255f17ca02b0106653dd600
Change-Id: I8ab073b30b4e27405a3b6da2c826bb4f3f0b9af6

14 files changed, 311 insertions, 302 deletions

diff --git a/absl/time/internal/cctz/src/time_zone_fixed.cc b/absl/time/internal/cctz/src/time_zone_fixed.cc
index 65eba356..598b08fd 100644
--- a/absl/time/internal/cctz/src/time_zone_fixed.cc
+++ b/absl/time/internal/cctz/src/time_zone_fixed.cc
@@ -42,9 +42,9 @@ int Parse02d(const char* p) {
 
 }  // namespace
 
-bool FixedOffsetFromName(const std::string& name, sys_seconds* offset) {
+bool FixedOffsetFromName(const std::string& name, seconds* offset) {
   if (name.compare(0, std::string::npos, "UTC", 3) == 0) {
-    *offset = sys_seconds::zero();
+    *offset = seconds::zero();
     return true;
   }
 
@@ -69,12 +69,12 @@ bool FixedOffsetFromName(const std::string& name, sys_seconds* offset) {
 
   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
+  *offset = seconds(secs * (np[0] == '-' ? -1 : 1));  // "-" means west
   return true;
 }
 
-std::string FixedOffsetToName(const sys_seconds& offset) {
-  if (offset == sys_seconds::zero()) return "UTC";
+std::string FixedOffsetToName(const seconds& offset) {
+  if (offset == 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
@@ -101,7 +101,7 @@ std::string FixedOffsetToName(const sys_seconds& offset) {
   return buf;
 }
 
-std::string FixedOffsetToAbbr(const sys_seconds& offset) {
+std::string FixedOffsetToAbbr(const seconds& offset) {
   std::string abbr = FixedOffsetToName(offset);
   const std::size_t prefix_len = sizeof(kFixedOffsetPrefix) - 1;
   if (abbr.size() == prefix_len + 9) {         // <prefix>+99:99:99
diff --git a/absl/time/internal/cctz/src/time_zone_fixed.h b/absl/time/internal/cctz/src/time_zone_fixed.h
index 7c9d11db..489b857d 100644
--- a/absl/time/internal/cctz/src/time_zone_fixed.h
+++ b/absl/time/internal/cctz/src/time_zone_fixed.h
@@ -38,9 +38,9 @@ namespace cctz {
 // 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);
+bool FixedOffsetFromName(const std::string& name, seconds* offset);
+std::string FixedOffsetToName(const seconds& offset);
+std::string FixedOffsetToAbbr(const seconds& offset);
 
 }  // namespace cctz
 }  // namespace time_internal
diff --git a/absl/time/internal/cctz/src/time_zone_format.cc b/absl/time/internal/cctz/src/time_zone_format.cc
index 6d5ccba1..592ab7d3 100644
--- a/absl/time/internal/cctz/src/time_zone_format.cc
+++ b/absl/time/internal/cctz/src/time_zone_format.cc
@@ -277,7 +277,7 @@ const std::int_fast64_t kExp10[kDigits10_64 + 1] = {
 // not support the tm_gmtoff and tm_zone extensions to std::tm.
 //
 // Requires that zero() <= fs < seconds(1).
-std::string format(const std::string& format, const time_point<sys_seconds>& tp,
+std::string format(const std::string& format, const time_point<seconds>& tp,
                    const detail::femtoseconds& fs, const time_zone& tz) {
   std::string result;
   result.reserve(format.size());  // A reasonable guess for the result size.
@@ -555,7 +555,7 @@ const char* ParseTM(const char* dp, const char* fmt, std::tm* tm) {
 // We also handle the %z specifier to accommodate platforms that do not
 // support the tm_gmtoff extension to std::tm.  %Z is parsed but ignored.
 bool parse(const std::string& format, const std::string& input,
-           const time_zone& tz, time_point<sys_seconds>* sec,
+           const time_zone& tz, time_point<seconds>* sec,
            detail::femtoseconds* fs, std::string* err) {
   // The unparsed input.
   const char* data = input.c_str();  // NUL terminated
@@ -822,15 +822,15 @@ bool parse(const std::string& format, const std::string& input,
 
   const auto tp = ptz.lookup(cs).pre;
   // Checks for overflow/underflow and returns an error as necessary.
-  if (tp == time_point<sys_seconds>::max()) {
-    const auto al = ptz.lookup(time_point<sys_seconds>::max());
+  if (tp == time_point<seconds>::max()) {
+    const auto al = ptz.lookup(time_point<seconds>::max());
     if (cs > al.cs) {
       if (err != nullptr) *err = "Out-of-range field";
       return false;
     }
   }
-  if (tp == time_point<sys_seconds>::min()) {
-    const auto al = ptz.lookup(time_point<sys_seconds>::min());
+  if (tp == time_point<seconds>::min()) {
+    const auto al = ptz.lookup(time_point<seconds>::min());
     if (cs < al.cs) {
       if (err != nullptr) *err = "Out-of-range field";
       return false;
diff --git a/absl/time/internal/cctz/src/time_zone_format_test.cc b/absl/time/internal/cctz/src/time_zone_format_test.cc
index 7d5b02ad..33c23984 100644
--- a/absl/time/internal/cctz/src/time_zone_format_test.cc
+++ b/absl/time/internal/cctz/src/time_zone_format_test.cc
@@ -23,15 +23,7 @@
 #include "gmock/gmock.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;
-using testing::HasSubstr;
+namespace chrono = std::chrono;
 
 namespace absl {
 namespace time_internal {
@@ -81,33 +73,36 @@ void TestFormatSpecifier(time_point<D> tp, time_zone tz, const std::string& fmt,
 TEST(Format, TimePointResolution) {
   const char kFmt[] = "%H:%M:%E*S";
   const time_zone utc = utc_time_zone();
-  const time_point<nanoseconds> t0 = system_clock::from_time_t(1420167845) +
-                                     milliseconds(123) + microseconds(456) +
-                                     nanoseconds(789);
-  EXPECT_EQ("03:04:05.123456789",
-            format(kFmt, time_point_cast<nanoseconds>(t0), utc));
-  EXPECT_EQ("03:04:05.123456",
-            format(kFmt, time_point_cast<microseconds>(t0), utc));
-  EXPECT_EQ("03:04:05.123",
-            format(kFmt, time_point_cast<milliseconds>(t0), utc));
+  const time_point<chrono::nanoseconds> t0 =
+      chrono::system_clock::from_time_t(1420167845) +
+      chrono::milliseconds(123) + chrono::microseconds(456) +
+      chrono::nanoseconds(789);
+  EXPECT_EQ(
+      "03:04:05.123456789",
+      format(kFmt, chrono::time_point_cast<chrono::nanoseconds>(t0), utc));
+  EXPECT_EQ(
+      "03:04:05.123456",
+      format(kFmt, chrono::time_point_cast<chrono::microseconds>(t0), utc));
+  EXPECT_EQ(
+      "03:04:05.123",
+      format(kFmt, chrono::time_point_cast<chrono::milliseconds>(t0), utc));
   EXPECT_EQ("03:04:05",
-            format(kFmt, time_point_cast<seconds>(t0), utc));
+            format(kFmt, chrono::time_point_cast<chrono::seconds>(t0), utc));
   EXPECT_EQ("03:04:05",
-            format(kFmt, time_point_cast<sys_seconds>(t0), utc));
+            format(kFmt, chrono::time_point_cast<absl::time_internal::cctz::seconds>(t0), utc));
   EXPECT_EQ("03:04:00",
-            format(kFmt, time_point_cast<minutes>(t0), utc));
+            format(kFmt, chrono::time_point_cast<chrono::minutes>(t0), utc));
   EXPECT_EQ("03:00:00",
-            format(kFmt, time_point_cast<hours>(t0), utc));
+            format(kFmt, chrono::time_point_cast<chrono::hours>(t0), utc));
 }
 
 TEST(Format, TimePointExtendedResolution) {
   const char kFmt[] = "%H:%M:%E*S";
   const time_zone utc = utc_time_zone();
-  const time_point<sys_seconds> tp =
-      std::chrono::time_point_cast<sys_seconds>(
-          std::chrono::system_clock::from_time_t(0)) +
-      std::chrono::hours(12) + std::chrono::minutes(34) +
-      std::chrono::seconds(56);
+  const time_point<absl::time_internal::cctz::seconds> tp =
+      chrono::time_point_cast<absl::time_internal::cctz::seconds>(
+          chrono::system_clock::from_time_t(0)) +
+      chrono::hours(12) + chrono::minutes(34) + chrono::seconds(56);
 
   EXPECT_EQ(
       "12:34:56.123456789012345",
@@ -132,7 +127,7 @@ TEST(Format, TimePointExtendedResolution) {
 
 TEST(Format, Basics) {
   time_zone tz = utc_time_zone();
-  time_point<nanoseconds> tp = system_clock::from_time_t(0);
+  time_point<chrono::nanoseconds> tp = chrono::system_clock::from_time_t(0);
 
   // Starts with a couple basic edge cases.
   EXPECT_EQ("", format("", tp, tz));
@@ -145,8 +140,9 @@ TEST(Format, Basics) {
   std::string bigger(100000, 'x');
   EXPECT_EQ(bigger, format(bigger, tp, tz));
 
-  tp += hours(13) + minutes(4) + seconds(5);
-  tp += milliseconds(6) + microseconds(7) + nanoseconds(8);
+  tp += chrono::hours(13) + chrono::minutes(4) + chrono::seconds(5);
+  tp += chrono::milliseconds(6) + chrono::microseconds(7) +
+        chrono::nanoseconds(8);
   EXPECT_EQ("1970-01-01", format("%Y-%m-%d", tp, tz));
   EXPECT_EQ("13:04:05", format("%H:%M:%S", tp, tz));
   EXPECT_EQ("13:04:05.006", format("%H:%M:%E3S", tp, tz));
@@ -156,7 +152,7 @@ TEST(Format, Basics) {
 
 TEST(Format, PosixConversions) {
   const time_zone tz = utc_time_zone();
-  auto tp = system_clock::from_time_t(0);
+  auto tp = chrono::system_clock::from_time_t(0);
 
   TestFormatSpecifier(tp, tz, "%d", "01");
   TestFormatSpecifier(tp, tz, "%e", " 1");  // extension but internal support
@@ -196,7 +192,7 @@ TEST(Format, PosixConversions) {
 
 TEST(Format, LocaleSpecific) {
   const time_zone tz = utc_time_zone();
-  auto tp = system_clock::from_time_t(0);
+  auto tp = chrono::system_clock::from_time_t(0);
 
   TestFormatSpecifier(tp, tz, "%a", "Thu");
   TestFormatSpecifier(tp, tz, "%A", "Thursday");
@@ -205,8 +201,8 @@ TEST(Format, LocaleSpecific) {
 
   // %c should at least produce the numeric year and time-of-day.
   const std::string s = format("%c", tp, utc_time_zone());
-  EXPECT_THAT(s, HasSubstr("1970"));
-  EXPECT_THAT(s, HasSubstr("00:00:00"));
+  EXPECT_THAT(s, testing::HasSubstr("1970"));
+  EXPECT_THAT(s, testing::HasSubstr("00:00:00"));
 
   TestFormatSpecifier(tp, tz, "%p", "AM");
   TestFormatSpecifier(tp, tz, "%x", "01/01/70");
@@ -245,7 +241,7 @@ TEST(Format, LocaleSpecific) {
 
 TEST(Format, Escaping) {
   const time_zone tz = utc_time_zone();
-  auto tp = system_clock::from_time_t(0);
+  auto tp = chrono::system_clock::from_time_t(0);
 
   TestFormatSpecifier(tp, tz, "%%", "%");
   TestFormatSpecifier(tp, tz, "%%a", "%a");
@@ -266,8 +262,8 @@ TEST(Format, ExtendedSeconds) {
   const time_zone tz = utc_time_zone();
 
   // No subseconds.
-  time_point<nanoseconds> tp = system_clock::from_time_t(0);
-  tp += seconds(5);
+  time_point<chrono::nanoseconds> tp = chrono::system_clock::from_time_t(0);
+  tp += chrono::seconds(5);
   EXPECT_EQ("05", format("%E*S", tp, tz));
   EXPECT_EQ("05", format("%E0S", tp, tz));
   EXPECT_EQ("05.0", format("%E1S", tp, tz));
@@ -287,7 +283,8 @@ TEST(Format, ExtendedSeconds) {
   EXPECT_EQ("05.000000000000000", format("%E15S", tp, tz));
 
   // With subseconds.
-  tp += milliseconds(6) + microseconds(7) + nanoseconds(8);
+  tp += chrono::milliseconds(6) + chrono::microseconds(7) +
+        chrono::nanoseconds(8);
   EXPECT_EQ("05.006007008", format("%E*S", tp, tz));
   EXPECT_EQ("05", format("%E0S", tp, tz));
   EXPECT_EQ("05.0", format("%E1S", tp, tz));
@@ -307,17 +304,18 @@ TEST(Format, ExtendedSeconds) {
   EXPECT_EQ("05.006007008000000", format("%E15S", tp, tz));
 
   // Times before the Unix epoch.
-  tp = system_clock::from_time_t(0) + microseconds(-1);
+  tp = chrono::system_clock::from_time_t(0) + chrono::microseconds(-1);
   EXPECT_EQ("1969-12-31 23:59:59.999999",
             format("%Y-%m-%d %H:%M:%E*S", tp, tz));
 
   // Here is a "%E*S" case we got wrong for a while.  While the first
   // instant below is correctly rendered as "...:07.333304", the second
   // one used to appear as "...:07.33330499999999999".
-  tp = system_clock::from_time_t(0) + microseconds(1395024427333304);
+  tp = chrono::system_clock::from_time_t(0) +
+       chrono::microseconds(1395024427333304);
   EXPECT_EQ("2014-03-17 02:47:07.333304",
             format("%Y-%m-%d %H:%M:%E*S", tp, tz));
-  tp += microseconds(1);
+  tp += chrono::microseconds(1);
   EXPECT_EQ("2014-03-17 02:47:07.333305",
             format("%Y-%m-%d %H:%M:%E*S", tp, tz));
 }
@@ -326,8 +324,8 @@ TEST(Format, ExtendedSubeconds) {
   const time_zone tz = utc_time_zone();
 
   // No subseconds.
-  time_point<nanoseconds> tp = system_clock::from_time_t(0);
-  tp += seconds(5);
+  time_point<chrono::nanoseconds> tp = chrono::system_clock::from_time_t(0);
+  tp += chrono::seconds(5);
   EXPECT_EQ("0", format("%E*f", tp, tz));
   EXPECT_EQ("", format("%E0f", tp, tz));
   EXPECT_EQ("0", format("%E1f", tp, tz));
@@ -347,7 +345,8 @@ TEST(Format, ExtendedSubeconds) {
   EXPECT_EQ("000000000000000", format("%E15f", tp, tz));
 
   // With subseconds.
-  tp += milliseconds(6) + microseconds(7) + nanoseconds(8);
+  tp += chrono::milliseconds(6) + chrono::microseconds(7) +
+        chrono::nanoseconds(8);
   EXPECT_EQ("006007008", format("%E*f", tp, tz));
   EXPECT_EQ("", format("%E0f", tp, tz));
   EXPECT_EQ("0", format("%E1f", tp, tz));
@@ -367,17 +366,18 @@ TEST(Format, ExtendedSubeconds) {
   EXPECT_EQ("006007008000000", format("%E15f", tp, tz));
 
   // Times before the Unix epoch.
-  tp = system_clock::from_time_t(0) + microseconds(-1);
+  tp = chrono::system_clock::from_time_t(0) + chrono::microseconds(-1);
   EXPECT_EQ("1969-12-31 23:59:59.999999",
             format("%Y-%m-%d %H:%M:%S.%E*f", tp, tz));
 
   // Here is a "%E*S" case we got wrong for a while.  While the first
   // instant below is correctly rendered as "...:07.333304", the second
   // one used to appear as "...:07.33330499999999999".
-  tp = system_clock::from_time_t(0) + microseconds(1395024427333304);
+  tp = chrono::system_clock::from_time_t(0) +
+       chrono::microseconds(1395024427333304);
   EXPECT_EQ("2014-03-17 02:47:07.333304",
             format("%Y-%m-%d %H:%M:%S.%E*f", tp, tz));
-  tp += microseconds(1);
+  tp += chrono::microseconds(1);
   EXPECT_EQ("2014-03-17 02:47:07.333305",
             format("%Y-%m-%d %H:%M:%S.%E*f", tp, tz));
 }
@@ -392,8 +392,8 @@ TEST(Format, CompareExtendSecondsVsSubseconds) {
   auto fmt_B = [](const std::string& prec) { return "%S.%E" + prec + "f"; };
 
   // No subseconds:
-  time_point<nanoseconds> tp = system_clock::from_time_t(0);
-  tp += seconds(5);
+  time_point<chrono::nanoseconds> tp = chrono::system_clock::from_time_t(0);
+  tp += chrono::seconds(5);
   // ... %E*S and %S.%E*f are different.
   EXPECT_EQ("05", format(fmt_A("*"), tp, tz));
   EXPECT_EQ("05.0", format(fmt_B("*"), tp, tz));
@@ -409,7 +409,8 @@ TEST(Format, CompareExtendSecondsVsSubseconds) {
 
   // With subseconds:
   // ... %E*S and %S.%E*f are the same.
-  tp += milliseconds(6) + microseconds(7) + nanoseconds(8);
+  tp += chrono::milliseconds(6) + chrono::microseconds(7) +
+        chrono::nanoseconds(8);
   EXPECT_EQ("05.006007008", format(fmt_A("*"), tp, tz));
   EXPECT_EQ("05.006007008", format(fmt_B("*"), tp, tz));
   // ... %E0S and %S.%E0f are different.
@@ -424,7 +425,7 @@ TEST(Format, CompareExtendSecondsVsSubseconds) {
 }
 
 TEST(Format, ExtendedOffset) {
-  auto tp = system_clock::from_time_t(0);
+  auto tp = chrono::system_clock::from_time_t(0);
 
   time_zone tz = utc_time_zone();
   TestFormatSpecifier(tp, tz, "%Ez", "+00:00");
@@ -446,7 +447,7 @@ TEST(Format, ExtendedOffset) {
 
 TEST(Format, ExtendedSecondOffset) {
   const time_zone utc = utc_time_zone();
-  time_point<seconds> tp;
+  time_point<chrono::seconds> tp;
   time_zone tz;
 
   EXPECT_TRUE(load_time_zone("America/New_York", &tz));
@@ -458,7 +459,7 @@ TEST(Format, ExtendedSecondOffset) {
     TestFormatSpecifier(tp, tz, "%E*z", "-04:56:02");
     TestFormatSpecifier(tp, tz, "%Ez", "-04:56");
   }
-  tp += seconds(1);
+  tp += chrono::seconds(1);
   TestFormatSpecifier(tp, tz, "%E*z", "-05:00:00");
 
   EXPECT_TRUE(load_time_zone("Europe/Moscow", &tz));
@@ -469,7 +470,7 @@ TEST(Format, ExtendedSecondOffset) {
   TestFormatSpecifier(tp, tz, "%E*z", "+04:31:19");
   TestFormatSpecifier(tp, tz, "%Ez", "+04:31");
 #endif
-  tp += seconds(1);
+  tp += chrono::seconds(1);
   TestFormatSpecifier(tp, tz, "%E*z", "+04:00:00");
 }
 
@@ -510,44 +511,44 @@ TEST(Format, RFC3339Format) {
   time_zone tz;
   EXPECT_TRUE(load_time_zone("America/Los_Angeles", &tz));
 
-  time_point<nanoseconds> tp =
+  time_point<chrono::nanoseconds> tp =
       convert(civil_second(1977, 6, 28, 9, 8, 7), tz);
   EXPECT_EQ("1977-06-28T09:08:07-07:00", format(RFC3339_full, tp, tz));
   EXPECT_EQ("1977-06-28T09:08:07-07:00", format(RFC3339_sec, tp, tz));
 
-  tp += milliseconds(100);
+  tp += chrono::milliseconds(100);
   EXPECT_EQ("1977-06-28T09:08:07.1-07:00", format(RFC3339_full, tp, tz));
   EXPECT_EQ("1977-06-28T09:08:07-07:00", format(RFC3339_sec, tp, tz));
 
-  tp += milliseconds(20);
+  tp += chrono::milliseconds(20);
   EXPECT_EQ("1977-06-28T09:08:07.12-07:00", format(RFC3339_full, tp, tz));
   EXPECT_EQ("1977-06-28T09:08:07-07:00", format(RFC3339_sec, tp, tz));
 
-  tp += milliseconds(3);
+  tp += chrono::milliseconds(3);
   EXPECT_EQ("1977-06-28T09:08:07.123-07:00", format(RFC3339_full, tp, tz));
   EXPECT_EQ("1977-06-28T09:08:07-07:00", format(RFC3339_sec, tp, tz));
 
-  tp += microseconds(400);
+  tp += chrono::microseconds(400);
   EXPECT_EQ("1977-06-28T09:08:07.1234-07:00", format(RFC3339_full, tp, tz));
   EXPECT_EQ("1977-06-28T09:08:07-07:00", format(RFC3339_sec, tp, tz));
 
-  tp += microseconds(50);
+  tp += chrono::microseconds(50);
   EXPECT_EQ("1977-06-28T09:08:07.12345-07:00", format(RFC3339_full, tp, tz));
   EXPECT_EQ("1977-06-28T09:08:07-07:00", format(RFC3339_sec, tp, tz));
 
-  tp += microseconds(6);
+  tp += chrono::microseconds(6);
   EXPECT_EQ("1977-06-28T09:08:07.123456-07:00", format(RFC3339_full, tp, tz));
   EXPECT_EQ("1977-06-28T09:08:07-07:00", format(RFC3339_sec, tp, tz));
 
-  tp += nanoseconds(700);
+  tp += chrono::nanoseconds(700);
   EXPECT_EQ("1977-06-28T09:08:07.1234567-07:00", format(RFC3339_full, tp, tz));
   EXPECT_EQ("1977-06-28T09:08:07-07:00", format(RFC3339_sec, tp, tz));
 
-  tp += nanoseconds(80);
+  tp += chrono::nanoseconds(80);
   EXPECT_EQ("1977-06-28T09:08:07.12345678-07:00", format(RFC3339_full, tp, tz));
   EXPECT_EQ("1977-06-28T09:08:07-07:00", format(RFC3339_sec, tp, tz));
 
-  tp += nanoseconds(9);
+  tp += chrono::nanoseconds(9);
   EXPECT_EQ("1977-06-28T09:08:07.123456789-07:00",
             format(RFC3339_full, tp, tz));
   EXPECT_EQ("1977-06-28T09:08:07-07:00", format(RFC3339_sec, tp, tz));
@@ -570,13 +571,13 @@ TEST(Parse, TimePointResolution) {
   const char kFmt[] = "%H:%M:%E*S";
   const time_zone utc = utc_time_zone();
 
-  time_point<nanoseconds> tp_ns;
+  time_point<chrono::nanoseconds> tp_ns;
   EXPECT_TRUE(parse(kFmt, "03:04:05.123456789", utc, &tp_ns));
   EXPECT_EQ("03:04:05.123456789", format(kFmt, tp_ns, utc));
   EXPECT_TRUE(parse(kFmt, "03:04:05.123456", utc, &tp_ns));
   EXPECT_EQ("03:04:05.123456", format(kFmt, tp_ns, utc));
 
-  time_point<microseconds> tp_us;
+  time_point<chrono::microseconds> tp_us;
   EXPECT_TRUE(parse(kFmt, "03:04:05.123456789", utc, &tp_us));
   EXPECT_EQ("03:04:05.123456", format(kFmt, tp_us, utc));
   EXPECT_TRUE(parse(kFmt, "03:04:05.123456", utc, &tp_us));
@@ -584,7 +585,7 @@ TEST(Parse, TimePointResolution) {
   EXPECT_TRUE(parse(kFmt, "03:04:05.123", utc, &tp_us));
   EXPECT_EQ("03:04:05.123", format(kFmt, tp_us, utc));
 
-  time_point<milliseconds> tp_ms;
+  time_point<chrono::milliseconds> tp_ms;
   EXPECT_TRUE(parse(kFmt, "03:04:05.123456", utc, &tp_ms));
   EXPECT_EQ("03:04:05.123", format(kFmt, tp_ms, utc));
   EXPECT_TRUE(parse(kFmt, "03:04:05.123", utc, &tp_ms));
@@ -592,17 +593,17 @@ TEST(Parse, TimePointResolution) {
   EXPECT_TRUE(parse(kFmt, "03:04:05", utc, &tp_ms));
   EXPECT_EQ("03:04:05", format(kFmt, tp_ms, utc));
 
-  time_point<seconds> tp_s;
+  time_point<chrono::seconds> tp_s;
   EXPECT_TRUE(parse(kFmt, "03:04:05.123", utc, &tp_s));
   EXPECT_EQ("03:04:05", format(kFmt, tp_s, utc));
   EXPECT_TRUE(parse(kFmt, "03:04:05", utc, &tp_s));
   EXPECT_EQ("03:04:05", format(kFmt, tp_s, utc));
 
-  time_point<minutes> tp_m;
+  time_point<chrono::minutes> tp_m;
   EXPECT_TRUE(parse(kFmt, "03:04:05", utc, &tp_m));
   EXPECT_EQ("03:04:00", format(kFmt, tp_m, utc));
 
-  time_point<hours> tp_h;
+  time_point<chrono::hours> tp_h;
   EXPECT_TRUE(parse(kFmt, "03:04:05", utc, &tp_h));
   EXPECT_EQ("03:00:00", format(kFmt, tp_h, utc));
 }
@@ -611,7 +612,7 @@ TEST(Parse, TimePointExtendedResolution) {
   const char kFmt[] = "%H:%M:%E*S";
   const time_zone utc = utc_time_zone();
 
-  time_point<sys_seconds> tp;
+  time_point<absl::time_internal::cctz::seconds> tp;
   detail::femtoseconds fs;
   EXPECT_TRUE(detail::parse(kFmt, "12:34:56.123456789012345", utc, &tp, &fs));
   EXPECT_EQ("12:34:56.123456789012345", detail::format(kFmt, tp, fs, utc));
@@ -629,11 +630,12 @@ TEST(Parse, TimePointExtendedResolution) {
 
 TEST(Parse, Basics) {
   time_zone tz = utc_time_zone();
-  time_point<nanoseconds> tp = system_clock::from_time_t(1234567890);
+  time_point<chrono::nanoseconds> tp =
+      chrono::system_clock::from_time_t(1234567890);
 
   // Simple edge cases.
   EXPECT_TRUE(parse("", "", tz, &tp));
-  EXPECT_EQ(system_clock::from_time_t(0), tp);  // everything defaulted
+  EXPECT_EQ(chrono::system_clock::from_time_t(0), tp);  // everything defaulted
   EXPECT_TRUE(parse(" ", " ", tz, &tp));
   EXPECT_TRUE(parse("  ", "  ", tz, &tp));
   EXPECT_TRUE(parse("x", "x", tz, &tp));
@@ -647,7 +649,7 @@ TEST(Parse, Basics) {
 TEST(Parse, WithTimeZone) {
   time_zone tz;
   EXPECT_TRUE(load_time_zone("America/Los_Angeles", &tz));
-  time_point<nanoseconds> tp;
+  time_point<chrono::nanoseconds> tp;
 
   // We can parse a std::string without a UTC offset if we supply a timezone.
   EXPECT_TRUE(parse("%Y-%m-%d %H:%M:%S", "2013-06-28 19:08:09", tz, &tp));
@@ -672,7 +674,7 @@ TEST(Parse, WithTimeZone) {
 TEST(Parse, LeapSecond) {
   time_zone tz;
   EXPECT_TRUE(load_time_zone("America/Los_Angeles", &tz));
-  time_point<nanoseconds> tp;
+  time_point<chrono::nanoseconds> tp;
 
   // ":59" -> ":59"
   EXPECT_TRUE(parse(RFC3339_full, "2013-06-28T07:08:59-08:00", tz, &tp));
@@ -696,7 +698,7 @@ TEST(Parse, LeapSecond) {
 
 TEST(Parse, ErrorCases) {
   const time_zone tz = utc_time_zone();
-  auto tp = system_clock::from_time_t(0);
+  auto tp = chrono::system_clock::from_time_t(0);
 
   // Illegal trailing data.
   EXPECT_FALSE(parse("%S", "123", tz, &tp));
@@ -739,7 +741,7 @@ TEST(Parse, ErrorCases) {
 
 TEST(Parse, PosixConversions) {
   time_zone tz = utc_time_zone();
-  auto tp = system_clock::from_time_t(0);
+  auto tp = chrono::system_clock::from_time_t(0);
   const auto reset = convert(civil_second(1977, 6, 28, 9, 8, 7), tz);
 
   tp = reset;
@@ -828,14 +830,14 @@ TEST(Parse, PosixConversions) {
 
   tp = reset;
   EXPECT_TRUE(parse("%s", "1234567890", tz, &tp));
-  EXPECT_EQ(system_clock::from_time_t(1234567890), tp);
+  EXPECT_EQ(chrono::system_clock::from_time_t(1234567890), tp);
 
   // %s conversion, like %z/%Ez, pays no heed to the optional zone.
   time_zone lax;
   EXPECT_TRUE(load_time_zone("America/Los_Angeles", &lax));
   tp = reset;
   EXPECT_TRUE(parse("%s", "1234567890", lax, &tp));
-  EXPECT_EQ(system_clock::from_time_t(1234567890), tp);
+  EXPECT_EQ(chrono::system_clock::from_time_t(1234567890), tp);
 
   // This is most important when the time has the same YMDhms
   // breakdown in the zone as some other time.  For example, ...
@@ -843,16 +845,16 @@ TEST(Parse, PosixConversions) {
   //  1414920600 in US/Pacific -> Sun Nov 2 01:30:00 2014 (PST)
   tp = reset;
   EXPECT_TRUE(parse("%s", "1414917000", lax, &tp));
-  EXPECT_EQ(system_clock::from_time_t(1414917000), tp);
+  EXPECT_EQ(chrono::system_clock::from_time_t(1414917000), tp);
   tp = reset;
   EXPECT_TRUE(parse("%s", "1414920600", lax, &tp));
-  EXPECT_EQ(system_clock::from_time_t(1414920600), tp);
+  EXPECT_EQ(chrono::system_clock::from_time_t(1414920600), tp);
 #endif
 }
 
 TEST(Parse, LocaleSpecific) {
   time_zone tz = utc_time_zone();
-  auto tp = system_clock::from_time_t(0);
+  auto tp = chrono::system_clock::from_time_t(0);
   const auto reset = convert(civil_second(1977, 6, 28, 9, 8, 7), tz);
 
   // %a is parsed but ignored.
@@ -983,7 +985,8 @@ TEST(Parse, LocaleSpecific) {
 
 TEST(Parse, ExtendedSeconds) {
   const time_zone tz = utc_time_zone();
-  const time_point<nanoseconds> unix_epoch = system_clock::from_time_t(0);
+  const time_point<chrono::nanoseconds> unix_epoch =
+      chrono::system_clock::from_time_t(0);
 
   // All %E<prec>S cases are treated the same as %E*S on input.
   auto precisions = {"*", "0", "1",  "2",  "3",  "4",  "5",  "6", "7",
@@ -991,47 +994,47 @@ TEST(Parse, ExtendedSeconds) {
   for (const std::string& prec : precisions) {
     const std::string fmt = "%E" + prec + "S";
     SCOPED_TRACE(fmt);
-    time_point<nanoseconds> tp = unix_epoch;
+    time_point<chrono::nanoseconds> tp = unix_epoch;
     EXPECT_TRUE(parse(fmt, "5", tz, &tp));
-    EXPECT_EQ(unix_epoch + seconds(5), tp);
+    EXPECT_EQ(unix_epoch + chrono::seconds(5), tp);
     tp = unix_epoch;
     EXPECT_TRUE(parse(fmt, "05", tz, &tp));
-    EXPECT_EQ(unix_epoch + seconds(5), tp);
+    EXPECT_EQ(unix_epoch + chrono::seconds(5), tp);
     tp = unix_epoch;
     EXPECT_TRUE(parse(fmt, "05.0", tz, &tp));
-    EXPECT_EQ(unix_epoch + seconds(5), tp);
+    EXPECT_EQ(unix_epoch + chrono::seconds(5), tp);
     tp = unix_epoch;
     EXPECT_TRUE(parse(fmt, "05.00", tz, &tp));
-    EXPECT_EQ(unix_epoch + seconds(5), tp);
+    EXPECT_EQ(unix_epoch + chrono::seconds(5), tp);
     tp = unix_epoch;
     EXPECT_TRUE(parse(fmt, "05.6", tz, &tp));
-    EXPECT_EQ(unix_epoch + seconds(5) + milliseconds(600), tp);
+    EXPECT_EQ(unix_epoch + chrono::seconds(5) + chrono::milliseconds(600), tp);
     tp = unix_epoch;
     EXPECT_TRUE(parse(fmt, "05.60", tz, &tp));
-    EXPECT_EQ(unix_epoch + seconds(5) + milliseconds(600), tp);
+    EXPECT_EQ(unix_epoch + chrono::seconds(5) + chrono::milliseconds(600), tp);
     tp = unix_epoch;
     EXPECT_TRUE(parse(fmt, "05.600", tz, &tp));
-    EXPECT_EQ(unix_epoch + seconds(5) + milliseconds(600), tp);
+    EXPECT_EQ(unix_epoch + chrono::seconds(5) + chrono::milliseconds(600), tp);
     tp = unix_epoch;
     EXPECT_TRUE(parse(fmt, "05.67", tz, &tp));
-    EXPECT_EQ(unix_epoch + seconds(5) + milliseconds(670), tp);
+    EXPECT_EQ(unix_epoch + chrono::seconds(5) + chrono::milliseconds(670), tp);
     tp = unix_epoch;
     EXPECT_TRUE(parse(fmt, "05.670", tz, &tp));
-    EXPECT_EQ(unix_epoch + seconds(5) + milliseconds(670), tp);
+    EXPECT_EQ(unix_epoch + chrono::seconds(5) + chrono::milliseconds(670), tp);
     tp = unix_epoch;
     EXPECT_TRUE(parse(fmt, "05.678", tz, &tp));
-    EXPECT_EQ(unix_epoch + seconds(5) + milliseconds(678), tp);
+    EXPECT_EQ(unix_epoch + chrono::seconds(5) + chrono::milliseconds(678), tp);
   }
 
   // Here is a "%E*S" case we got wrong for a while.  The fractional
   // part of the first instant is less than 2^31 and was correctly
   // parsed, while the second (and any subsecond field >=2^31) failed.
-  time_point<nanoseconds> tp = unix_epoch;
+  time_point<chrono::nanoseconds> tp = unix_epoch;
   EXPECT_TRUE(parse("%E*S", "0.2147483647", tz, &tp));
-  EXPECT_EQ(unix_epoch + nanoseconds(214748364), tp);
+  EXPECT_EQ(unix_epoch + chrono::nanoseconds(214748364), tp);
   tp = unix_epoch;
   EXPECT_TRUE(parse("%E*S", "0.2147483648", tz, &tp));
-  EXPECT_EQ(unix_epoch + nanoseconds(214748364), tp);
+  EXPECT_EQ(unix_epoch + chrono::nanoseconds(214748364), tp);
 
   // We should also be able to specify long strings of digits far
   // beyond the current resolution and have them convert the same way.
@@ -1039,18 +1042,18 @@ TEST(Parse, ExtendedSeconds) {
   EXPECT_TRUE(parse(
       "%E*S", "0.214748364801234567890123456789012345678901234567890123456789",
       tz, &tp));
-  EXPECT_EQ(unix_epoch + nanoseconds(214748364), tp);
+  EXPECT_EQ(unix_epoch + chrono::nanoseconds(214748364), tp);
 }
 
 TEST(Parse, ExtendedSecondsScan) {
   const time_zone tz = utc_time_zone();
-  time_point<nanoseconds> tp;
+  time_point<chrono::nanoseconds> tp;
   for (int ms = 0; ms < 1000; ms += 111) {
     for (int us = 0; us < 1000; us += 27) {
       const int micros = ms * 1000 + us;
       for (int ns = 0; ns < 1000; ns += 9) {
-        const auto expected =
-            system_clock::from_time_t(0) + nanoseconds(micros * 1000 + ns);
+        const auto expected = chrono::system_clock::from_time_t(0) +
+                              chrono::nanoseconds(micros * 1000 + ns);
         std::ostringstream oss;
         oss << "0." << std::setfill('0') << std::setw(3);
         oss << ms << std::setw(3) << us << std::setw(3) << ns;
@@ -1064,7 +1067,8 @@ TEST(Parse, ExtendedSecondsScan) {
 
 TEST(Parse, ExtendedSubeconds) {
   const time_zone tz = utc_time_zone();
-  const time_point<nanoseconds> unix_epoch = system_clock::from_time_t(0);
+  const time_point<chrono::nanoseconds> unix_epoch =
+      chrono::system_clock::from_time_t(0);
 
   // All %E<prec>f cases are treated the same as %E*f on input.
   auto precisions = {"*", "0", "1",  "2",  "3",  "4",  "5",  "6", "7",
@@ -1072,41 +1076,42 @@ TEST(Parse, ExtendedSubeconds) {
   for (const std::string& prec : precisions) {
     const std::string fmt = "%E" + prec + "f";
     SCOPED_TRACE(fmt);
-    time_point<nanoseconds> tp = unix_epoch - seconds(1);
+    time_point<chrono::nanoseconds> tp = unix_epoch - chrono::seconds(1);
     EXPECT_TRUE(parse(fmt, "", tz, &tp));
     EXPECT_EQ(unix_epoch, tp);
     tp = unix_epoch;
     EXPECT_TRUE(parse(fmt, "6", tz, &tp));
-    EXPECT_EQ(unix_epoch + milliseconds(600), tp);
+    EXPECT_EQ(unix_epoch + chrono::milliseconds(600), tp);
     tp = unix_epoch;
     EXPECT_TRUE(parse(fmt, "60", tz, &tp));
-    EXPECT_EQ(unix_epoch + milliseconds(600), tp);
+    EXPECT_EQ(unix_epoch + chrono::milliseconds(600), tp);
     tp = unix_epoch;
     EXPECT_TRUE(parse(fmt, "600", tz, &tp));
-    EXPECT_EQ(unix_epoch + milliseconds(600), tp);
+    EXPECT_EQ(unix_epoch + chrono::milliseconds(600), tp);
     tp = unix_epoch;
     EXPECT_TRUE(parse(fmt, "67", tz, &tp));
-    EXPECT_EQ(unix_epoch + milliseconds(670), tp);
+    EXPECT_EQ(unix_epoch + chrono::milliseconds(670), tp);
     tp = unix_epoch;
     EXPECT_TRUE(parse(fmt, "670", tz, &tp));
-    EXPECT_EQ(unix_epoch + milliseconds(670), tp);
+    EXPECT_EQ(unix_epoch + chrono::milliseconds(670), tp);
     tp = unix_epoch;
     EXPECT_TRUE(parse(fmt, "678", tz, &tp));
-    EXPECT_EQ(unix_epoch + milliseconds(678), tp);
+    EXPECT_EQ(unix_epoch + chrono::milliseconds(678), tp);
     tp = unix_epoch;
     EXPECT_TRUE(parse(fmt, "6789", tz, &tp));
-    EXPECT_EQ(unix_epoch + milliseconds(678) + microseconds(900), tp);
+    EXPECT_EQ(
+        unix_epoch + chrono::milliseconds(678) + chrono::microseconds(900), tp);
   }
 
   // Here is a "%E*f" case we got wrong for a while.  The fractional
   // part of the first instant is less than 2^31 and was correctly
   // parsed, while the second (and any subsecond field >=2^31) failed.
-  time_point<nanoseconds> tp = unix_epoch;
+  time_point<chrono::nanoseconds> tp = unix_epoch;
   EXPECT_TRUE(parse("%E*f", "2147483647", tz, &tp));
-  EXPECT_EQ(unix_epoch + nanoseconds(214748364), tp);
+  EXPECT_EQ(unix_epoch + chrono::nanoseconds(214748364), tp);
   tp = unix_epoch;
   EXPECT_TRUE(parse("%E*f", "2147483648", tz, &tp));
-  EXPECT_EQ(unix_epoch + nanoseconds(214748364), tp);
+  EXPECT_EQ(unix_epoch + chrono::nanoseconds(214748364), tp);
 
   // We should also be able to specify long strings of digits far
   // beyond the current resolution and have them convert the same way.
@@ -1114,11 +1119,11 @@ TEST(Parse, ExtendedSubeconds) {
   EXPECT_TRUE(parse(
       "%E*f", "214748364801234567890123456789012345678901234567890123456789",
       tz, &tp));
-  EXPECT_EQ(unix_epoch + nanoseconds(214748364), tp);
+  EXPECT_EQ(unix_epoch + chrono::nanoseconds(214748364), tp);
 }
 
 TEST(Parse, ExtendedSubecondsScan) {
-  time_point<nanoseconds> tp;
+  time_point<chrono::nanoseconds> tp;
   const time_zone tz = utc_time_zone();
   for (int ms = 0; ms < 1000; ms += 111) {
     for (int us = 0; us < 1000; us += 27) {
@@ -1128,14 +1133,14 @@ TEST(Parse, ExtendedSubecondsScan) {
         oss << std::setfill('0') << std::setw(3) << ms;
         oss << std::setw(3) << us << std::setw(3) << ns;
         const std::string nanos = oss.str();
-        const auto expected =
-            system_clock::from_time_t(0) + nanoseconds(micros * 1000 + ns);
+        const auto expected = chrono::system_clock::from_time_t(0) +
+                              chrono::nanoseconds(micros * 1000 + ns);
         for (int ps = 0; ps < 1000; ps += 250) {
           std::ostringstream oss;
           oss << std::setfill('0') << std::setw(3) << ps;
           const std::string input = nanos + oss.str() + "999";
           EXPECT_TRUE(parse("%E*f", input, tz, &tp));
-          EXPECT_EQ(expected + nanoseconds(ps) / 1000, tp) << input;
+          EXPECT_EQ(expected + chrono::nanoseconds(ps) / 1000, tp) << input;
         }
       }
     }
@@ -1144,7 +1149,7 @@ TEST(Parse, ExtendedSubecondsScan) {
 
 TEST(Parse, ExtendedOffset) {
   const time_zone utc = utc_time_zone();
-  time_point<sys_seconds> tp;
+  time_point<absl::time_internal::cctz::seconds> tp;
 
   // %z against +-HHMM.
   EXPECT_TRUE(parse("%z", "+0000", utc, &tp));
@@ -1194,7 +1199,7 @@ TEST(Parse, ExtendedOffset) {
 
 TEST(Parse, ExtendedSecondOffset) {
   const time_zone utc = utc_time_zone();
-  time_point<sys_seconds> tp;
+  time_point<absl::time_internal::cctz::seconds> tp;
 
   // %Ez against +-HH:MM:SS.
   EXPECT_TRUE(parse("%Ez", "+00:00:00", utc, &tp));
@@ -1263,7 +1268,7 @@ TEST(Parse, ExtendedSecondOffset) {
 TEST(Parse, ExtendedYears) {
   const time_zone utc = utc_time_zone();
   const char e4y_fmt[] = "%E4Y%m%d";  // no separators
-  time_point<sys_seconds> tp;
+  time_point<absl::time_internal::cctz::seconds> tp;
 
   // %E4Y consumes exactly four chars, including any sign.
   EXPECT_TRUE(parse(e4y_fmt, "-9991127", utc, &tp));
@@ -1294,45 +1299,45 @@ TEST(Parse, ExtendedYears) {
 
 TEST(Parse, RFC3339Format) {
   const time_zone tz = utc_time_zone();
-  time_point<nanoseconds> tp;
+  time_point<chrono::nanoseconds> tp;
   EXPECT_TRUE(parse(RFC3339_sec, "2014-02-12T20:21:00+00:00", tz, &tp));
   ExpectTime(tp, tz, 2014, 2, 12, 20, 21, 0, 0, false, "UTC");
 
   // Check that %Ez also accepts "Z" as a synonym for "+00:00".
-  time_point<nanoseconds> tp2;
+  time_point<chrono::nanoseconds> tp2;
   EXPECT_TRUE(parse(RFC3339_sec, "2014-02-12T20:21:00Z", tz, &tp2));
   EXPECT_EQ(tp, tp2);
 }
 
 TEST(Parse, MaxRange) {
   const time_zone utc = utc_time_zone();
-  time_point<sys_seconds> tp;
+  time_point<absl::time_internal::cctz::seconds> tp;
 
   // tests the upper limit using +00:00 offset
   EXPECT_TRUE(
       parse(RFC3339_sec, "292277026596-12-04T15:30:07+00:00", utc, &tp));
-  EXPECT_EQ(tp, time_point<sys_seconds>::max());
+  EXPECT_EQ(tp, time_point<absl::time_internal::cctz::seconds>::max());
   EXPECT_FALSE(
       parse(RFC3339_sec, "292277026596-12-04T15:30:08+00:00", utc, &tp));
 
   // tests the upper limit using -01:00 offset
   EXPECT_TRUE(
       parse(RFC3339_sec, "292277026596-12-04T14:30:07-01:00", utc, &tp));
-  EXPECT_EQ(tp, time_point<sys_seconds>::max());
+  EXPECT_EQ(tp, time_point<absl::time_internal::cctz::seconds>::max());
   EXPECT_FALSE(
       parse(RFC3339_sec, "292277026596-12-04T15:30:07-01:00", utc, &tp));
 
   // tests the lower limit using +00:00 offset
   EXPECT_TRUE(
       parse(RFC3339_sec, "-292277022657-01-27T08:29:52+00:00", utc, &tp));
-  EXPECT_EQ(tp, time_point<sys_seconds>::min());
+  EXPECT_EQ(tp, time_point<absl::time_internal::cctz::seconds>::min());
   EXPECT_FALSE(
       parse(RFC3339_sec, "-292277022657-01-27T08:29:51+00:00", utc, &tp));
 
   // tests the lower limit using +01:00 offset
   EXPECT_TRUE(
       parse(RFC3339_sec, "-292277022657-01-27T09:29:52+01:00", utc, &tp));
-  EXPECT_EQ(tp, time_point<sys_seconds>::min());
+  EXPECT_EQ(tp, time_point<absl::time_internal::cctz::seconds>::min());
   EXPECT_FALSE(
       parse(RFC3339_sec, "-292277022657-01-27T08:29:51+01:00", utc, &tp));
 
@@ -1355,11 +1360,11 @@ TEST(FormatParse, RoundTrip) {
   time_zone lax;
   EXPECT_TRUE(load_time_zone("America/Los_Angeles", &lax));
   const auto in = convert(civil_second(1977, 6, 28, 9, 8, 7), lax);
-  const auto subseconds = nanoseconds(654321);
+  const auto subseconds = chrono::nanoseconds(654321);
 
   // RFC3339, which renders subseconds.
   {
-    time_point<nanoseconds> out;
+    time_point<chrono::nanoseconds> out;
     const std::string s = format(RFC3339_full, in + subseconds, lax);
     EXPECT_TRUE(parse(RFC3339_full, s, lax, &out)) << s;
     EXPECT_EQ(in + subseconds, out);  // RFC3339_full includes %Ez
@@ -1367,7 +1372,7 @@ TEST(FormatParse, RoundTrip) {
 
   // RFC1123, which only does whole seconds.
   {
-    time_point<nanoseconds> out;
+    time_point<chrono::nanoseconds> out;
     const std::string s = format(RFC1123_full, in, lax);
     EXPECT_TRUE(parse(RFC1123_full, s, lax, &out)) << s;
     EXPECT_EQ(in, out);  // RFC1123_full includes %z
@@ -1380,7 +1385,7 @@ TEST(FormatParse, RoundTrip) {
   // Even though we don't know what %c will produce, it should roundtrip,
   // but only in the 0-offset timezone.
   {
-    time_point<nanoseconds> out;
+    time_point<chrono::nanoseconds> out;
     time_zone utc = utc_time_zone();
     const std::string s = format("%c", in, utc);
     EXPECT_TRUE(parse("%c", s, utc, &out)) << s;
@@ -1391,18 +1396,18 @@ TEST(FormatParse, RoundTrip) {
 
 TEST(FormatParse, RoundTripDistantFuture) {
   const time_zone utc = utc_time_zone();
-  const time_point<sys_seconds> in = time_point<sys_seconds>::max();
+  const time_point<absl::time_internal::cctz::seconds> in = time_point<absl::time_internal::cctz::seconds>::max();
   const std::string s = format(RFC3339_full, in, utc);
-  time_point<sys_seconds> out;
+  time_point<absl::time_internal::cctz::seconds> out;
   EXPECT_TRUE(parse(RFC3339_full, s, utc, &out)) << s;
   EXPECT_EQ(in, out);
 }
 
 TEST(FormatParse, RoundTripDistantPast) {
   const time_zone utc = utc_time_zone();
-  const time_point<sys_seconds> in = time_point<sys_seconds>::min();
+  const time_point<absl::time_internal::cctz::seconds> in = time_point<absl::time_internal::cctz::seconds>::min();
   const std::string s = format(RFC3339_full, in, utc);
-  time_point<sys_seconds> out;
+  time_point<absl::time_internal::cctz::seconds> out;
   EXPECT_TRUE(parse(RFC3339_full, s, utc, &out)) << s;
   EXPECT_EQ(in, out);
 }
diff --git a/absl/time/internal/cctz/src/time_zone_if.h b/absl/time/internal/cctz/src/time_zone_if.h
index ce4da1b7..f10972ae 100644
--- a/absl/time/internal/cctz/src/time_zone_if.h
+++ b/absl/time/internal/cctz/src/time_zone_if.h
@@ -37,30 +37,28 @@ class TimeZoneIf {
   virtual ~TimeZoneIf();
 
   virtual time_zone::absolute_lookup BreakTime(
-      const time_point<sys_seconds>& tp) const = 0;
+      const time_point<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;
+  virtual bool NextTransition(time_point<seconds>* tp) const = 0;
+  virtual bool PrevTransition(time_point<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
+// Convert between time_point<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 std::int_fast64_t ToUnixSeconds(const time_point<seconds>& tp) {
+  return (tp - std::chrono::time_point_cast<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);
+inline time_point<seconds> FromUnixSeconds(std::int_fast64_t t) {
+  return std::chrono::time_point_cast<seconds>(
+             std::chrono::system_clock::from_time_t(0)) + seconds(t);
 }
 
 }  // namespace cctz
diff --git a/absl/time/internal/cctz/src/time_zone_impl.cc b/absl/time/internal/cctz/src/time_zone_impl.cc
index b3f635f7..eb96c7ef 100644
--- a/absl/time/internal/cctz/src/time_zone_impl.cc
+++ b/absl/time/internal/cctz/src/time_zone_impl.cc
@@ -45,8 +45,8 @@ 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()) {
+  auto offset = seconds::zero();
+  if (FixedOffsetFromName(name, &offset) && offset == seconds::zero()) {
     *tz = time_zone(utc_impl);
     return true;
   }
diff --git a/absl/time/internal/cctz/src/time_zone_impl.h b/absl/time/internal/cctz/src/time_zone_impl.h
index 2c1c30b6..fef7f226 100644
--- a/absl/time/internal/cctz/src/time_zone_impl.h
+++ b/absl/time/internal/cctz/src/time_zone_impl.h
@@ -48,8 +48,7 @@ class time_zone::Impl {
   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 {
+  time_zone::absolute_lookup BreakTime(const time_point<seconds>& tp) const {
     return zone_->BreakTime(tp);
   }
 
@@ -75,10 +74,10 @@ class time_zone::Impl {
   // 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 {
+  bool NextTransition(time_point<seconds>* tp) const {
     return zone_->NextTransition(tp);
   }
-  bool PrevTransition(time_point<sys_seconds>* tp) const {
+  bool PrevTransition(time_point<seconds>* tp) const {
     return zone_->PrevTransition(tp);
   }
 
diff --git a/absl/time/internal/cctz/src/time_zone_info.cc b/absl/time/internal/cctz/src/time_zone_info.cc
index 20bba28b..cdd11810 100644
--- a/absl/time/internal/cctz/src/time_zone_info.cc
+++ b/absl/time/internal/cctz/src/time_zone_info.cc
@@ -140,7 +140,7 @@ std::int_fast64_t TransOffset(bool leap_year, int jan1_weekday,
   return (days * kSecsPerDay) + pt.time.offset;
 }
 
-inline time_zone::civil_lookup MakeUnique(const time_point<sys_seconds>& tp) {
+inline time_zone::civil_lookup MakeUnique(const time_point<seconds>& tp) {
   time_zone::civil_lookup cl;
   cl.kind = time_zone::civil_lookup::UNIQUE;
   cl.pre = cl.trans = cl.post = tp;
@@ -179,7 +179,7 @@ inline civil_second YearShift(const civil_second& cs, year_t shift) {
 }  // namespace
 
 // What (no leap-seconds) UTC+seconds zoneinfo would look like.
-bool TimeZoneInfo::ResetToBuiltinUTC(const sys_seconds& offset) {
+bool TimeZoneInfo::ResetToBuiltinUTC(const seconds& offset) {
   transition_types_.resize(1);
   TransitionType& tt(transition_types_.back());
   tt.utc_offset = static_cast<std::int_least32_t>(offset.count());
@@ -218,8 +218,8 @@ bool TimeZoneInfo::ResetToBuiltinUTC(const sys_seconds& offset) {
   future_spec_.clear();  // never needed for a fixed-offset zone
   extended_ = false;
 
-  tt.civil_max = LocalTime(sys_seconds::max().count(), tt).cs;
-  tt.civil_min = LocalTime(sys_seconds::min().count(), tt).cs;
+  tt.civil_max = LocalTime(seconds::max().count(), tt).cs;
+  tt.civil_min = LocalTime(seconds::min().count(), tt).cs;
 
   transitions_.shrink_to_fit();
   return true;
@@ -565,10 +565,10 @@ bool TimeZoneInfo::Load(const std::string& name, ZoneInfoSource* zip) {
   }
 
   // Compute the maximum/minimum civil times that can be converted to a
-  // time_point<sys_seconds> for each of the zone's transition types.
+  // time_point<seconds> for each of the zone's transition types.
   for (auto& tt : transition_types_) {
-    tt.civil_max = LocalTime(sys_seconds::max().count(), tt).cs;
-    tt.civil_min = LocalTime(sys_seconds::min().count(), tt).cs;
+    tt.civil_max = LocalTime(seconds::max().count(), tt).cs;
+    tt.civil_min = LocalTime(seconds::min().count(), tt).cs;
   }
 
   transitions_.shrink_to_fit();
@@ -713,7 +713,7 @@ bool TimeZoneInfo::Load(const std::string& name) {
   // zone never fails because the simple, fixed-offset state can be
   // internally generated. Note that this depends on our choice to not
   // accept leap-second encoded ("right") zoneinfo.
-  auto offset = sys_seconds::zero();
+  auto offset = seconds::zero();
   if (FixedOffsetFromName(name, &offset)) {
     return ResetToBuiltinUTC(offset);
   }
@@ -755,14 +755,14 @@ time_zone::civil_lookup TimeZoneInfo::TimeLocal(const civil_second& cs,
                                                 year_t c4_shift) const {
   assert(last_year_ - 400 < cs.year() && cs.year() <= last_year_);
   time_zone::civil_lookup cl = MakeTime(cs);
-  if (c4_shift > sys_seconds::max().count() / kSecsPer400Years) {
-    cl.pre = cl.trans = cl.post = time_point<sys_seconds>::max();
+  if (c4_shift > seconds::max().count() / kSecsPer400Years) {
+    cl.pre = cl.trans = cl.post = time_point<seconds>::max();
   } else {
-    const auto offset = sys_seconds(c4_shift * kSecsPer400Years);
-    const auto limit = time_point<sys_seconds>::max() - offset;
+    const auto offset = seconds(c4_shift * kSecsPer400Years);
+    const auto limit = time_point<seconds>::max() - offset;
     for (auto* tp : {&cl.pre, &cl.trans, &cl.post}) {
       if (*tp > limit) {
-        *tp = time_point<sys_seconds>::max();
+        *tp = time_point<seconds>::max();
       } else {
         *tp += offset;
       }
@@ -772,7 +772,7 @@ time_zone::civil_lookup TimeZoneInfo::TimeLocal(const civil_second& cs,
 }
 
 time_zone::absolute_lookup TimeZoneInfo::BreakTime(
-    const time_point<sys_seconds>& tp) const {
+    const time_point<seconds>& tp) const {
   std::int_fast64_t unix_time = ToUnixSeconds(tp);
   const std::size_t timecnt = transitions_.size();
   assert(timecnt != 0);  // We always add a transition.
@@ -788,7 +788,7 @@ time_zone::absolute_lookup TimeZoneInfo::BreakTime(
       const std::int_fast64_t diff =
           unix_time - transitions_[timecnt - 1].unix_time;
       const year_t shift = diff / kSecsPer400Years + 1;
-      const auto d = sys_seconds(shift * kSecsPer400Years);
+      const auto d = seconds(shift * kSecsPer400Years);
       time_zone::absolute_lookup al = BreakTime(tp - d);
       al.cs = YearShift(al.cs, shift * 400);
       return al;
@@ -847,7 +847,7 @@ time_zone::civil_lookup TimeZoneInfo::MakeTime(const civil_second& cs) const {
     if (tr->prev_civil_sec >= cs) {
       // Before first transition, so use the default offset.
       const TransitionType& tt(transition_types_[default_transition_type_]);
-      if (cs < tt.civil_min) return MakeUnique(time_point<sys_seconds>::min());
+      if (cs < tt.civil_min) return MakeUnique(time_point<seconds>::min());
       return MakeUnique(cs - (civil_second() + tt.utc_offset));
     }
     // tr->prev_civil_sec < cs < tr->civil_sec
@@ -864,7 +864,7 @@ time_zone::civil_lookup TimeZoneInfo::MakeTime(const civil_second& cs) const {
         return TimeLocal(YearShift(cs, shift * -400), shift);
       }
       const TransitionType& tt(transition_types_[tr->type_index]);
-      if (cs > tt.civil_max) return MakeUnique(time_point<sys_seconds>::max());
+      if (cs > tt.civil_max) return MakeUnique(time_point<seconds>::max());
       return MakeUnique(tr->unix_time + (cs - tr->civil_sec));
     }
     // tr->civil_sec <= cs <= tr->prev_civil_sec
@@ -895,7 +895,7 @@ std::string TimeZoneInfo::Description() const {
   return oss.str();
 }
 
-bool TimeZoneInfo::NextTransition(time_point<sys_seconds>* tp) const {
+bool TimeZoneInfo::NextTransition(time_point<seconds>* tp) const {
   if (transitions_.empty()) return false;
   const Transition* begin = &transitions_[0];
   const Transition* end = begin + transitions_.size();
@@ -919,7 +919,7 @@ bool TimeZoneInfo::NextTransition(time_point<sys_seconds>* tp) const {
   return true;
 }
 
-bool TimeZoneInfo::PrevTransition(time_point<sys_seconds>* tp) const {
+bool TimeZoneInfo::PrevTransition(time_point<seconds>* tp) const {
   if (transitions_.empty()) return false;
   const Transition* begin = &transitions_[0];
   const Transition* end = begin + transitions_.size();
diff --git a/absl/time/internal/cctz/src/time_zone_info.h b/absl/time/internal/cctz/src/time_zone_info.h
index b4d1696b..d28443e2 100644
--- a/absl/time/internal/cctz/src/time_zone_info.h
+++ b/absl/time/internal/cctz/src/time_zone_info.h
@@ -71,12 +71,12 @@ class TimeZoneInfo : public TimeZoneIf {
 
   // TimeZoneIf implementations.
   time_zone::absolute_lookup BreakTime(
-      const time_point<sys_seconds>& tp) const override;
+      const time_point<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;
+  bool NextTransition(time_point<seconds>* tp) const override;
+  bool PrevTransition(time_point<seconds>* tp) const override;
 
  private:
   struct Header {  // counts of:
@@ -98,7 +98,7 @@ class TimeZoneInfo : public TimeZoneIf {
                         std::uint_fast8_t tt2_index) const;
   void ExtendTransitions(const std::string& name, const Header& hdr);
 
-  bool ResetToBuiltinUTC(const sys_seconds& offset);
+  bool ResetToBuiltinUTC(const seconds& offset);
   bool Load(const std::string& name, ZoneInfoSource* zip);
 
   // Helpers for BreakTime() and MakeTime().
diff --git a/absl/time/internal/cctz/src/time_zone_libc.cc b/absl/time/internal/cctz/src/time_zone_libc.cc
index b0b56a52..1d727bde 100644
--- a/absl/time/internal/cctz/src/time_zone_libc.cc
+++ b/absl/time/internal/cctz/src/time_zone_libc.cc
@@ -91,7 +91,7 @@ TimeZoneLibC::TimeZoneLibC(const std::string& name)
     : local_(name == "localtime") {}
 
 time_zone::absolute_lookup TimeZoneLibC::BreakTime(
-    const time_point<sys_seconds>& tp) const {
+    const time_point<seconds>& tp) const {
   time_zone::absolute_lookup al;
   std::time_t t = ToUnixSeconds(tp);
   std::tm tm;
@@ -143,11 +143,11 @@ std::string TimeZoneLibC::Description() const {
   return local_ ? "localtime" : "UTC";
 }
 
-bool TimeZoneLibC::NextTransition(time_point<sys_seconds>* tp) const {
+bool TimeZoneLibC::NextTransition(time_point<seconds>* tp) const {
   return false;
 }
 
-bool TimeZoneLibC::PrevTransition(time_point<sys_seconds>* tp) const {
+bool TimeZoneLibC::PrevTransition(time_point<seconds>* tp) const {
   return false;
 }
 
diff --git a/absl/time/internal/cctz/src/time_zone_libc.h b/absl/time/internal/cctz/src/time_zone_libc.h
index 41f7dde2..4c64cd34 100644
--- a/absl/time/internal/cctz/src/time_zone_libc.h
+++ b/absl/time/internal/cctz/src/time_zone_libc.h
@@ -32,12 +32,12 @@ class TimeZoneLibC : public TimeZoneIf {
 
   // TimeZoneIf implementations.
   time_zone::absolute_lookup BreakTime(
-      const time_point<sys_seconds>& tp) const override;
+      const time_point<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;
+  bool NextTransition(time_point<seconds>* tp) const override;
+  bool PrevTransition(time_point<seconds>* tp) const override;
 
  private:
   const bool local_;  // localtime or UTC
diff --git a/absl/time/internal/cctz/src/time_zone_lookup.cc b/absl/time/internal/cctz/src/time_zone_lookup.cc
index d549d862..2f6cd98b 100644
--- a/absl/time/internal/cctz/src/time_zone_lookup.cc
+++ b/absl/time/internal/cctz/src/time_zone_lookup.cc
@@ -65,7 +65,7 @@ std::string time_zone::name() const {
 }
 
 time_zone::absolute_lookup time_zone::lookup(
-    const time_point<sys_seconds>& tp) const {
+    const time_point<seconds>& tp) const {
   return time_zone::Impl::get(*this).BreakTime(tp);
 }
 
@@ -85,7 +85,7 @@ time_zone utc_time_zone() {
   return time_zone::Impl::UTC();  // avoid name lookup
 }
 
-time_zone fixed_time_zone(const sys_seconds& offset) {
+time_zone fixed_time_zone(const seconds& offset) {
   time_zone tz;
   load_time_zone(FixedOffsetToName(offset), &tz);
   return tz;
diff --git a/absl/time/internal/cctz/src/time_zone_lookup_test.cc b/absl/time/internal/cctz/src/time_zone_lookup_test.cc
index 06b172a8..cd9fc236 100644
--- a/absl/time/internal/cctz/src/time_zone_lookup_test.cc
+++ b/absl/time/internal/cctz/src/time_zone_lookup_test.cc
@@ -24,14 +24,7 @@
 #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 chrono = std::chrono;
 
 namespace absl {
 namespace time_internal {
@@ -715,13 +708,13 @@ TEST(TimeZone, NamedTimeZones) {
   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());
+  const time_zone fixed0 = fixed_time_zone(absl::time_internal::cctz::seconds::zero());
   EXPECT_EQ("UTC", fixed0.name());
-  const time_zone fixed_pos =
-      fixed_time_zone(hours(3) + minutes(25) + seconds(45));
+  const time_zone fixed_pos = fixed_time_zone(
+      chrono::hours(3) + chrono::minutes(25) + chrono::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)));
+  const time_zone fixed_neg = fixed_time_zone(
+      -(chrono::hours(12) + chrono::minutes(34) + chrono::seconds(56)));
   EXPECT_EQ("Fixed/UTC-12:34:56", fixed_neg.name());
 }
 
@@ -731,19 +724,19 @@ TEST(TimeZone, Failures) {
 
   tz = LoadZone("America/Los_Angeles");
   EXPECT_FALSE(load_time_zone("Invalid/TimeZone", &tz));
-  EXPECT_EQ(system_clock::from_time_t(0),
+  EXPECT_EQ(chrono::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),
+  EXPECT_EQ(chrono::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),
+  EXPECT_EQ(chrono::system_clock::from_time_t(0),
             convert(civil_second(1970, 1, 1, 0, 0, 0), tz));  // UTC
 }
 
@@ -758,7 +751,7 @@ TEST(TimeZone, Equality) {
   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());
+  const time_zone fixed_zero = fixed_time_zone(absl::time_internal::cctz::seconds::zero());
   EXPECT_EQ(fixed_zero, LoadZone(fixed_zero.name()));
   EXPECT_EQ(fixed_zero, explicit_utc);
 
@@ -766,23 +759,25 @@ TEST(TimeZone, Equality) {
   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));
+  const time_zone fixed_pos = fixed_time_zone(
+      chrono::hours(3) + chrono::minutes(25) + chrono::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)));
+  const time_zone fixed_neg = fixed_time_zone(
+      -(chrono::hours(12) + chrono::minutes(34) + chrono::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));
+  const time_zone fixed_lim = fixed_time_zone(chrono::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));
+  const time_zone fixed_ovfl =
+      fixed_time_zone(chrono::hours(24) + chrono::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)));
+  EXPECT_EQ(fixed_time_zone(chrono::seconds(1)),
+            fixed_time_zone(chrono::seconds(1)));
 
   const time_zone local = local_time_zone();
   EXPECT_EQ(local, LoadZone(local.name()));
@@ -795,40 +790,43 @@ TEST(TimeZone, Equality) {
 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));
+  auto diff = chrono::system_clock::time_point() -
+              chrono::system_clock::from_time_t(0);
+  EXPECT_EQ(chrono::system_clock::time_point::duration::zero(),
+            diff % chrono::seconds(1));
 }
 
 TEST(BreakTime, TimePointResolution) {
   const time_zone utc = utc_time_zone();
-  const auto t0 = system_clock::from_time_t(0);
+  const auto t0 = chrono::system_clock::from_time_t(0);
 
-  ExpectTime(time_point_cast<nanoseconds>(t0), utc,
+  ExpectTime(chrono::time_point_cast<chrono::nanoseconds>(t0), utc,
              1970, 1, 1, 0, 0, 0, 0, false, "UTC");
-  ExpectTime(time_point_cast<microseconds>(t0), utc,
+  ExpectTime(chrono::time_point_cast<chrono::microseconds>(t0), utc,
              1970, 1, 1, 0, 0, 0, 0, false, "UTC");
-  ExpectTime(time_point_cast<milliseconds>(t0), utc,
+  ExpectTime(chrono::time_point_cast<chrono::milliseconds>(t0), utc,
              1970, 1, 1, 0, 0, 0, 0, false, "UTC");
-  ExpectTime(time_point_cast<seconds>(t0), utc,
+  ExpectTime(chrono::time_point_cast<chrono::seconds>(t0), utc,
              1970, 1, 1, 0, 0, 0, 0, false, "UTC");
-  ExpectTime(time_point_cast<sys_seconds>(t0), utc,
+  ExpectTime(chrono::time_point_cast<absl::time_internal::cctz::seconds>(t0), utc,
              1970, 1, 1, 0, 0, 0, 0, false, "UTC");
-  ExpectTime(time_point_cast<minutes>(t0), utc,
+  ExpectTime(chrono::time_point_cast<chrono::minutes>(t0), utc,
              1970, 1, 1, 0, 0, 0, 0, false, "UTC");
-  ExpectTime(time_point_cast<hours>(t0), utc,
+  ExpectTime(chrono::time_point_cast<chrono::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);
+  const auto tp = chrono::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);
+  const auto tp =
+      chrono::system_clock::from_time_t(0) - chrono::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))));
 }
@@ -836,15 +834,16 @@ TEST(BreakTime, LocalTimeInUTCUnaligned) {
 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);
+  const auto tp = chrono::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 absl::time_internal::cctz::seconds offset =
+      -(chrono::hours(8) + chrono::minutes(33) + chrono::seconds(47));
   const time_zone tz = fixed_time_zone(offset);
-  const auto tp = system_clock::from_time_t(0);
+  const auto tp = chrono::system_clock::from_time_t(0);
   ExpectTime(tp, tz, 1969, 12, 31, 15, 26, 13, offset.count(), false,
              "-083347");
   EXPECT_EQ(weekday::wednesday, get_weekday(civil_day(convert(tp, tz))));
@@ -852,52 +851,52 @@ TEST(TimeZoneImpl, LocalTimeInFixed) {
 
 TEST(BreakTime, LocalTimeInNewYork) {
   const time_zone tz = LoadZone("America/New_York");
-  const auto tp = system_clock::from_time_t(45);
+  const auto tp = chrono::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);
+  const auto tp = chrono::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);
+  const auto tp = chrono::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 =
+  const time_point<chrono::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 =
+  const time_point<chrono::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 =
+  const time_point<chrono::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 =
+  const time_point<chrono::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 =
+  const time_point<absl::time_internal::cctz::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>(
+  // These next two require chrono::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<chrono::minutes> tp_m =
+      chrono::time_point_cast<chrono::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>(
+  const time_point<chrono::hours> tp_h =
+      chrono::time_point_cast<chrono::hours>(
           convert(civil_second(2015, 1, 2, 3, 4, 5), utc));
   EXPECT_EQ("00:00", format("%M:%E*S", tp_h, utc));
 }
@@ -905,7 +904,7 @@ TEST(MakeTime, TimePointResolution) {
 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);
+  EXPECT_EQ(chrono::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
@@ -919,67 +918,67 @@ TEST(MakeTime, Normalization) {
 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;
+  const time_zone east = fixed_time_zone(chrono::hours(14));
+  const time_zone west = fixed_time_zone(-chrono::hours(14));
+  time_point<absl::time_internal::cctz::seconds> tp;
 
-  // Approach the maximal time_point<sys_seconds> value from below.
+  // Approach the maximal time_point<cctz::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);
+  EXPECT_EQ(time_point<absl::time_internal::cctz::seconds>::max(), tp);
   tp = convert(civil_second(292277026596, 12, 4, 15, 30, 8), utc);
-  EXPECT_EQ(time_point<sys_seconds>::max(), tp);
+  EXPECT_EQ(time_point<absl::time_internal::cctz::seconds>::max(), tp);
   tp = convert(civil_second::max(), utc);
-  EXPECT_EQ(time_point<sys_seconds>::max(), tp);
+  EXPECT_EQ(time_point<absl::time_internal::cctz::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);
+  EXPECT_EQ(time_point<absl::time_internal::cctz::seconds>::max(), tp);
   tp = convert(civil_second(292277026596, 12, 5, 5, 30, 8), east);
-  EXPECT_EQ(time_point<sys_seconds>::max(), tp);
+  EXPECT_EQ(time_point<absl::time_internal::cctz::seconds>::max(), tp);
   tp = convert(civil_second::max(), east);
-  EXPECT_EQ(time_point<sys_seconds>::max(), tp);
+  EXPECT_EQ(time_point<absl::time_internal::cctz::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);
+  EXPECT_EQ(time_point<absl::time_internal::cctz::seconds>::max(), tp);
   tp = convert(civil_second(292277026596, 12, 4, 7, 30, 8), west);
-  EXPECT_EQ(time_point<sys_seconds>::max(), tp);
+  EXPECT_EQ(time_point<absl::time_internal::cctz::seconds>::max(), tp);
   tp = convert(civil_second::max(), west);
-  EXPECT_EQ(time_point<sys_seconds>::max(), tp);
+  EXPECT_EQ(time_point<absl::time_internal::cctz::seconds>::max(), tp);
 
-  // Approach the minimal time_point<sys_seconds> value from above.
+  // Approach the minimal time_point<cctz::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);
+  EXPECT_EQ(time_point<absl::time_internal::cctz::seconds>::min(), tp);
   tp = convert(civil_second(-292277022657, 1, 27, 8, 29, 51), utc);
-  EXPECT_EQ(time_point<sys_seconds>::min(), tp);
+  EXPECT_EQ(time_point<absl::time_internal::cctz::seconds>::min(), tp);
   tp = convert(civil_second::min(), utc);
-  EXPECT_EQ(time_point<sys_seconds>::min(), tp);
+  EXPECT_EQ(time_point<absl::time_internal::cctz::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);
+  EXPECT_EQ(time_point<absl::time_internal::cctz::seconds>::min(), tp);
   tp = convert(civil_second(-292277022657, 1, 27, 22, 29, 51), east);
-  EXPECT_EQ(time_point<sys_seconds>::min(), tp);
+  EXPECT_EQ(time_point<absl::time_internal::cctz::seconds>::min(), tp);
   tp = convert(civil_second::min(), east);
-  EXPECT_EQ(time_point<sys_seconds>::min(), tp);
+  EXPECT_EQ(time_point<absl::time_internal::cctz::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);
+  EXPECT_EQ(time_point<absl::time_internal::cctz::seconds>::min(), tp);
   tp = convert(civil_second(-292277022657, 1, 26, 18, 29, 51), west);
-  EXPECT_EQ(time_point<sys_seconds>::min(), tp);
+  EXPECT_EQ(time_point<absl::time_internal::cctz::seconds>::min(), tp);
   tp = convert(civil_second::min(), west);
-  EXPECT_EQ(time_point<sys_seconds>::min(), tp);
+  EXPECT_EQ(time_point<absl::time_internal::cctz::seconds>::min(), tp);
 }
 
 TEST(TimeZoneEdgeCase, AmericaNewYork) {
@@ -988,13 +987,13 @@ TEST(TimeZoneEdgeCase, AmericaNewYork) {
   // 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);
+  tp += absl::time_internal::cctz::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);
+  tp += absl::time_internal::cctz::seconds(1);
   ExpectTime(tp, tz, 2013, 11, 3, 1, 0, 0, -5 * 3600, false, "EST");
 }
 
@@ -1004,13 +1003,13 @@ TEST(TimeZoneEdgeCase, AmericaLosAngeles) {
   // 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);
+  tp += absl::time_internal::cctz::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);
+  tp += absl::time_internal::cctz::seconds(1);
   ExpectTime(tp, tz, 2013, 11, 3, 1, 0, 0, -8 * 3600, false, "PST");
 }
 
@@ -1020,13 +1019,13 @@ TEST(TimeZoneEdgeCase, ArizonaNoTransition) {
   // 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);
+  tp += absl::time_internal::cctz::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);
+  tp += absl::time_internal::cctz::seconds(1);
   ExpectTime(tp, tz, 2013, 11, 3, 2, 0, 0, -7 * 3600, false, "MST");
 }
 
@@ -1039,7 +1038,7 @@ TEST(TimeZoneEdgeCase, AsiaKathmandu) {
   //   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);
+  tp += absl::time_internal::cctz::seconds(1);
   ExpectTime(tp, tz, 1986, 1, 1, 0, 15, 0, 5.75 * 3600, false, "+0545");
 }
 
@@ -1052,14 +1051,14 @@ TEST(TimeZoneEdgeCase, PacificChatham) {
   //   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);
+  tp += absl::time_internal::cctz::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);
+  tp += absl::time_internal::cctz::seconds(1);
   ExpectTime(tp, tz, 2013, 9, 29, 3, 45, 0, 13.75 * 3600, true, "+1345");
 }
 
@@ -1072,14 +1071,14 @@ TEST(TimeZoneEdgeCase, AustraliaLordHowe) {
   //   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);
+  tp += absl::time_internal::cctz::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);
+  tp += absl::time_internal::cctz::seconds(1);
   ExpectTime(tp, tz, 2013, 10, 6, 2, 30, 0, 11 * 3600, true, "+11");
 }
 
@@ -1097,7 +1096,7 @@ TEST(TimeZoneEdgeCase, PacificApia) {
   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);
+  tp += absl::time_internal::cctz::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))));
 }
@@ -1114,7 +1113,7 @@ TEST(TimeZoneEdgeCase, AfricaCairo) {
   //   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);
+  tp += absl::time_internal::cctz::seconds(1);
   ExpectTime(tp, tz, 2014, 5, 16, 1, 0, 0, 3 * 3600, true, "EEST");
 #endif
 }
@@ -1131,7 +1130,7 @@ TEST(TimeZoneEdgeCase, AfricaMonrovia) {
   //   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);
+  tp += absl::time_internal::cctz::seconds(1);
   ExpectTime(tp, tz, 1972, 1, 7, 0, 44, 30, 0 * 60, false, "GMT");
 #endif
 }
@@ -1159,7 +1158,7 @@ TEST(TimeZoneEdgeCase, AmericaJamaica) {
   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);
+  tp += absl::time_internal::cctz::seconds(1);
   ExpectTime(tp, tz, 1890, 1, 1, 0, 0, 0, -18430, false, "KMT");
 #endif
 
@@ -1168,7 +1167,7 @@ TEST(TimeZoneEdgeCase, AmericaJamaica) {
   //     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);
+  tp += absl::time_internal::cctz::seconds(1);
   ExpectTime(tp, tz, 1983, 10, 30, 1, 0, 0, -5 * 3600, false, "EST");
 
   // After the last transition.
@@ -1189,7 +1188,7 @@ TEST(TimeZoneEdgeCase, 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);
+  tp += absl::time_internal::cctz::seconds(1);
   ExpectTime(tp, tz, 1977, 4, 3, 2, 0, 0, 1 * 3600, true, "WEST");
 
   // A non-existent time within the first transition.
@@ -1211,12 +1210,12 @@ 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);
+  EXPECT_EQ(chrono::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);
+  EXPECT_EQ(chrono::system_clock::from_time_t(-5 * 3600), tp);
 }
 
 TEST(TimeZoneEdgeCase, NegativeYear) {
@@ -1225,7 +1224,7 @@ TEST(TimeZoneEdgeCase, NegativeYear) {
   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);
+  tp -= absl::time_internal::cctz::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))));
 }
@@ -1239,7 +1238,7 @@ TEST(TimeZoneEdgeCase, UTC32bitLimit) {
   //   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);
+  tp += absl::time_internal::cctz::seconds(1);
   ExpectTime(tp, tz, 2038, 1, 19, 3, 14, 8, 0 * 3600, false, "UTC");
 }
 
@@ -1252,7 +1251,7 @@ TEST(TimeZoneEdgeCase, UTC5DigitYear) {
   //   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);
+  tp += absl::time_internal::cctz::seconds(1);
   ExpectTime(tp, tz, 10000, 1, 1, 0, 0, 0, 0 * 3600, false, "UTC");
 }
 
diff --git a/absl/time/internal/cctz/src/zone_info_source.cc b/absl/time/internal/cctz/src/zone_info_source.cc
index b77c0a58..ee7500b6 100644
--- a/absl/time/internal/cctz/src/zone_info_source.cc
+++ b/absl/time/internal/cctz/src/zone_info_source.cc
@@ -60,9 +60,17 @@ ZoneInfoSourceFactory default_factory = DefaultFactory;
 #else
 #error Unsupported MSVC platform
 #endif
-#else
+#else  // _MSC_VER
+#if !defined(__has_attribute)
+#define __has_attribute(x) 0
+#endif
+#if __has_attribute(weak) || defined(__GNUC__)
 ZoneInfoSourceFactory zone_info_source_factory
     __attribute__((weak)) = DefaultFactory;
+#else
+// Make it a "strong" definition if we have no other choice.
+ZoneInfoSourceFactory zone_info_source_factory = DefaultFactory;
+#endif
 #endif  // _MSC_VER
 
 }  // namespace cctz_extension