7 files changed, 70 insertions, 22 deletions
diff --git a/absl/time/internal/cctz/include/cctz/civil_time_detail.h b/absl/time/internal/cctz/include/cctz/civil_time_detail.h
index 5fe0967f..d7f72717 100644
--- a/absl/time/internal/cctz/include/cctz/civil_time_detail.h
+++ b/absl/time/internal/cctz/include/cctz/civil_time_detail.h
@@ -416,6 +416,12 @@ class civil_time {
     return difference(T{}, lhs.f_, rhs.f_);
   }
 
+  template <typename H>
+  friend H AbslHashValue(H h, civil_time a) {
+    return H::combine(std::move(h), a.f_.y, a.f_.m, a.f_.d,
+                                    a.f_.hh, a.f_.mm, a.f_.ss);
+  }
+
  private:
   // All instantiations of this template are allowed to call the following
   // private constructor and access the private fields member.
diff --git a/absl/time/internal/cctz/include/cctz/time_zone.h b/absl/time/internal/cctz/include/cctz/time_zone.h
index c86a5552..f28dad17 100644
--- a/absl/time/internal/cctz/include/cctz/time_zone.h
+++ b/absl/time/internal/cctz/include/cctz/time_zone.h
@@ -224,6 +224,11 @@ class time_zone {
     return !(lhs == rhs);
   }
 
+  template <typename H>
+  friend H AbslHashValue(H h, time_zone tz) {
+    return H::combine(std::move(h), &tz.effective_impl());
+  }
+
   class Impl;
 
  private:
diff --git a/absl/time/internal/cctz/src/civil_time_test.cc b/absl/time/internal/cctz/src/civil_time_test.cc
index f6648c8f..faffde47 100644
--- a/absl/time/internal/cctz/src/civil_time_test.cc
+++ b/absl/time/internal/cctz/src/civil_time_test.cc
@@ -620,7 +620,7 @@ TEST(CivilTime, Relational) {
   TEST_RELATIONAL(civil_second(2014, 1, 1, 1, 1, 0),
                   civil_second(2014, 1, 1, 1, 1, 1));
 
-  // Tests the relational operators of two different CivilTime types.
+  // Tests the relational operators of two different civil-time types.
   TEST_RELATIONAL(civil_day(2014, 1, 1), civil_minute(2014, 1, 1, 1, 1));
   TEST_RELATIONAL(civil_day(2014, 1, 1), civil_month(2014, 2));
 
diff --git a/absl/time/internal/cctz/src/time_zone_fixed.cc b/absl/time/internal/cctz/src/time_zone_fixed.cc
index 598b08fd..db9a475a 100644
--- a/absl/time/internal/cctz/src/time_zone_fixed.cc
+++ b/absl/time/internal/cctz/src/time_zone_fixed.cc
@@ -15,8 +15,8 @@
 #include "time_zone_fixed.h"
 
 #include <algorithm>
+#include <cassert>
 #include <chrono>
-#include <cstdio>
 #include <cstring>
 #include <string>
 
@@ -29,8 +29,15 @@ namespace {
 // The prefix used for the internal names of fixed-offset zones.
 const char kFixedOffsetPrefix[] = "Fixed/UTC";
 
+const char kDigits[] = "0123456789";
+
+char* Format02d(char* p, int v) {
+  *p++ = kDigits[(v / 10) % 10];
+  *p++ = kDigits[v % 10];
+  return p;
+}
+
 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)) {
@@ -95,9 +102,17 @@ std::string FixedOffsetToName(const seconds& offset) {
   }
   int hours = minutes / 60;
   minutes %= 60;
-  char buf[sizeof(kFixedOffsetPrefix) + sizeof("-24:00:00")];
-  snprintf(buf, sizeof(buf), "%s%c%02d:%02d:%02d",
-           kFixedOffsetPrefix, sign, hours, minutes, seconds);
+  char buf[sizeof(kFixedOffsetPrefix) - 1 + sizeof("-24:00:00")];
+  std::strcpy(buf, kFixedOffsetPrefix);
+  char* ep = buf + sizeof(kFixedOffsetPrefix) - 1;
+  *ep++ = sign;
+  ep = Format02d(ep, hours);
+  *ep++ = ':';
+  ep = Format02d(ep, minutes);
+  *ep++ = ':';
+  ep = Format02d(ep, seconds);
+  *ep++ = '\0';
+  assert(ep == buf + sizeof(buf));
   return buf;
 }
 
diff --git a/absl/time/internal/cctz/src/time_zone_libc.cc b/absl/time/internal/cctz/src/time_zone_libc.cc
index 074c8d0a..e35fa18b 100644
--- a/absl/time/internal/cctz/src/time_zone_libc.cc
+++ b/absl/time/internal/cctz/src/time_zone_libc.cc
@@ -111,7 +111,7 @@ time_zone::absolute_lookup TimeZoneLibC::BreakTime(
     al.offset = 0;
     al.abbr = "UTC";
   }
-  al.cs = civil_second(tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
+  al.cs = civil_second(tm.tm_year + year_t{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;
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 551292fb..f28e7f85 100644
--- a/absl/time/internal/cctz/src/time_zone_lookup_test.cc
+++ b/absl/time/internal/cctz/src/time_zone_lookup_test.cc
@@ -990,6 +990,18 @@ TEST(MakeTime, SysSecondsLimits) {
   EXPECT_EQ(time_point<absl::time_internal::cctz::seconds>::min(), tp);
   tp = convert(civil_second::min(), west);
   EXPECT_EQ(time_point<absl::time_internal::cctz::seconds>::min(), tp);
+
+  if (sizeof(std::time_t) >= 8) {
+    // Checks that "tm_year + 1900", as used by the "libc" implementation,
+    // can produce year values beyond the range on an int without overflow.
+#if defined(_WIN32) || defined(_WIN64)
+    // localtime_s() and gmtime_s() don't believe in years past 3000.
+#else
+    const time_zone libc_utc = LoadZone("libc:UTC");
+    tp = convert(civil_year(year_t{2147483648}), libc_utc);
+    EXPECT_EQ("2147483648-01-01T00:00:00+00:00", format(RFC3339, tp, libc_utc));
+#endif
+  }
 }
 
 TEST(NextTransition, UTC) {
diff --git a/absl/time/internal/cctz/src/time_zone_posix.h b/absl/time/internal/cctz/src/time_zone_posix.h
index 9ccd4a8b..ef2a8c16 100644
--- a/absl/time/internal/cctz/src/time_zone_posix.h
+++ b/absl/time/internal/cctz/src/time_zone_posix.h
@@ -68,25 +68,35 @@ namespace cctz {
 // it would take us to another day, and perhaps week, or even month.
 struct PosixTransition {
   enum DateFormat { J, N, M };
-  struct {
+
+  struct Date {
+    struct NonLeapDay {
+      std::int_fast16_t day;  // day of non-leap year [1:365]
+    };
+    struct Day {
+      std::int_fast16_t day;  // day of year [0:365]
+    };
+    struct MonthWeekWeekday {
+      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
+    };
+
     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;
+      NonLeapDay j;
+      Day n;
+      MonthWeekWeekday m;
     };
-  } date;
-  struct {
+  };
+
+  struct Time {
     std::int_fast32_t offset;  // seconds before/after 00:00:00
-  } time;
+  };
+
+  Date date;
+  Time time;
 };
 
 // The entirety of a POSIX-string specified time-zone rule. The standard