merge(3p/absl): subtree merge of Abseil up to e19260f r/1889

... notably, this includes Abseil's own StatusOr type, which
conflicted with our implementation (that was taken from TensorFlow).

Change-Id: Ie7d6764b64055caaeb8dc7b6b9d066291e6b538f

6 files changed, 186 insertions, 150 deletions

diff --git a/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_format.cc b/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_format.cc
index 2e02233ce1..d8cb047425 100644
--- a/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_format.cc
+++ b/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_format.cc
@@ -654,14 +654,23 @@ const char* ParseTM(const char* dp, const char* fmt, std::tm* tm) {
 }
 
 // Sets year, tm_mon and tm_mday given the year, week_num, and tm_wday,
-// and the day on which weeks are defined to start.
-void FromWeek(int week_num, weekday week_start, year_t* year, std::tm* tm) {
+// and the day on which weeks are defined to start.  Returns false if year
+// would need to move outside its bounds.
+bool FromWeek(int week_num, weekday week_start, year_t* year, std::tm* tm) {
   const civil_year y(*year % 400);
   civil_day cd = prev_weekday(y, week_start);  // week 0
   cd = next_weekday(cd - 1, FromTmWday(tm->tm_wday)) + (week_num * 7);
-  *year += cd.year() - y.year();
+  if (const year_t shift = cd.year() - y.year()) {
+    if (shift > 0) {
+      if (*year > std::numeric_limits<year_t>::max() - shift) return false;
+    } else {
+      if (*year < std::numeric_limits<year_t>::min() - shift) return false;
+    }
+    *year += shift;
+  }
   tm->tm_mon = cd.month() - 1;
   tm->tm_mday = cd.day();
+  return true;
 }
 
 }  // namespace
@@ -965,7 +974,12 @@ bool parse(const std::string& format, const std::string& input,
   }
 
   // Compute year, tm.tm_mon and tm.tm_mday if we parsed a week number.
-  if (week_num != -1) FromWeek(week_num, week_start, &year, &tm);
+  if (week_num != -1) {
+    if (!FromWeek(week_num, week_start, &year, &tm)) {
+      if (err != nullptr) *err = "Out-of-range field";
+      return false;
+    }
+  }
 
   const int month = tm.tm_mon + 1;
   civil_second cs(year, month, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec);
diff --git a/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_format_test.cc b/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_format_test.cc
index e625a839fa..a11f93e2a5 100644
--- a/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_format_test.cc
+++ b/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_format_test.cc
@@ -1481,6 +1481,11 @@ TEST(Parse, WeekYearShift) {
   EXPECT_EQ(exp, tp);
   EXPECT_TRUE(parse("%Y-%W-%w", "2020-52-5", utc, &tp));
   EXPECT_EQ(exp, tp);
+
+  // Slipping into the previous/following calendar years should fail when
+  // we're already at the extremes.
+  EXPECT_FALSE(parse("%Y-%U-%u", "-9223372036854775808-0-7", utc, &tp));
+  EXPECT_FALSE(parse("%Y-%U-%u", "9223372036854775807-53-7", utc, &tp));
 }
 
 TEST(Parse, MaxRange) {
diff --git a/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_info.cc b/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_info.cc
index 665fb424fe..8039353e58 100644
--- a/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_info.cc
+++ b/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_info.cc
@@ -40,7 +40,6 @@
 #include <cstdlib>
 #include <cstring>
 #include <functional>
-#include <iostream>
 #include <memory>
 #include <sstream>
 #include <string>
@@ -83,6 +82,27 @@ const std::int_least32_t kSecsPerYear[2] = {
     366 * kSecsPerDay,
 };
 
+// Convert a cctz::weekday to a POSIX TZ weekday number (0==Sun, ..., 6=Sat).
+inline int ToPosixWeekday(weekday wd) {
+  switch (wd) {
+    case weekday::sunday:
+      return 0;
+    case weekday::monday:
+      return 1;
+    case weekday::tuesday:
+      return 2;
+    case weekday::wednesday:
+      return 3;
+    case weekday::thursday:
+      return 4;
+    case weekday::friday:
+      return 5;
+    case weekday::saturday:
+      return 6;
+  }
+  return 0; /*NOTREACHED*/
+}
+
 // Single-byte, unsigned numeric values are encoded directly.
 inline std::uint_fast8_t Decode8(const char* cp) {
   return static_cast<std::uint_fast8_t>(*cp) & 0xff;
@@ -188,15 +208,13 @@ bool TimeZoneInfo::ResetToBuiltinUTC(const seconds& offset) {
   tt.is_dst = false;
   tt.abbr_index = 0;
 
-  // We temporarily add some redundant, contemporary (2013 through 2023)
+  // We temporarily add some redundant, contemporary (2015 through 2025)
   // transitions for performance reasons.  See TimeZoneInfo::LocalTime().
   // TODO: Fix the performance issue and remove the extra transitions.
   transitions_.clear();
   transitions_.reserve(12);
   for (const std::int_fast64_t unix_time : {
-           -(1LL << 59),  // BIG_BANG
-           1356998400LL,  // 2013-01-01T00:00:00+00:00
-           1388534400LL,  // 2014-01-01T00:00:00+00:00
+           -(1LL << 59),  // a "first half" transition
            1420070400LL,  // 2015-01-01T00:00:00+00:00
            1451606400LL,  // 2016-01-01T00:00:00+00:00
            1483228800LL,  // 2017-01-01T00:00:00+00:00
@@ -206,7 +224,8 @@ bool TimeZoneInfo::ResetToBuiltinUTC(const seconds& offset) {
            1609459200LL,  // 2021-01-01T00:00:00+00:00
            1640995200LL,  // 2022-01-01T00:00:00+00:00
            1672531200LL,  // 2023-01-01T00:00:00+00:00
-           2147483647LL,  // 2^31 - 1
+           1704067200LL,  // 2024-01-01T00:00:00+00:00
+           1735689600LL,  // 2025-01-01T00:00:00+00:00
        }) {
     Transition& tr(*transitions_.emplace(transitions_.end()));
     tr.unix_time = unix_time;
@@ -217,8 +236,8 @@ bool TimeZoneInfo::ResetToBuiltinUTC(const seconds& offset) {
 
   default_transition_type_ = 0;
   abbreviations_ = FixedOffsetToAbbr(offset);
-  abbreviations_.append(1, '\0');  // add NUL
-  future_spec_.clear();            // never needed for a fixed-offset zone
+  abbreviations_.append(1, '\0');
+  future_spec_.clear();  // never needed for a fixed-offset zone
   extended_ = false;
 
   tt.civil_max = LocalTime(seconds::max().count(), tt).cs;
@@ -259,21 +278,6 @@ std::size_t TimeZoneInfo::Header::DataLength(std::size_t time_len) const {
   return len;
 }
 
-// Check that the TransitionType has the expected offset/is_dst/abbreviation.
-void TimeZoneInfo::CheckTransition(const std::string& name,
-                                   const TransitionType& tt,
-                                   std::int_fast32_t offset, bool is_dst,
-                                   const std::string& abbr) const {
-  if (tt.utc_offset != offset || tt.is_dst != is_dst ||
-      &abbreviations_[tt.abbr_index] != abbr) {
-    std::clog << name << ": Transition"
-              << " offset=" << tt.utc_offset << "/"
-              << (tt.is_dst ? "DST" : "STD")
-              << "/abbr=" << &abbreviations_[tt.abbr_index]
-              << " does not match POSIX spec '" << future_spec_ << "'\n";
-  }
-}
-
 // zic(8) can generate no-op transitions when a zone changes rules at an
 // instant when there is actually no discontinuity.  So we check whether
 // two transitions have equivalent types (same offset/is_dst/abbr).
@@ -282,117 +286,108 @@ bool TimeZoneInfo::EquivTransitions(std::uint_fast8_t tt1_index,
   if (tt1_index == tt2_index) return true;
   const TransitionType& tt1(transition_types_[tt1_index]);
   const TransitionType& tt2(transition_types_[tt2_index]);
-  if (tt1.is_dst != tt2.is_dst) return false;
   if (tt1.utc_offset != tt2.utc_offset) return false;
+  if (tt1.is_dst != tt2.is_dst) return false;
   if (tt1.abbr_index != tt2.abbr_index) return false;
   return true;
 }
 
+// Find/make a transition type with these attributes.
+bool TimeZoneInfo::GetTransitionType(std::int_fast32_t utc_offset, bool is_dst,
+                                     const std::string& abbr,
+                                     std::uint_least8_t* index) {
+  std::size_t type_index = 0;
+  std::size_t abbr_index = abbreviations_.size();
+  for (; type_index != transition_types_.size(); ++type_index) {
+    const TransitionType& tt(transition_types_[type_index]);
+    const char* tt_abbr = &abbreviations_[tt.abbr_index];
+    if (tt_abbr == abbr) abbr_index = tt.abbr_index;
+    if (tt.utc_offset == utc_offset && tt.is_dst == is_dst) {
+      if (abbr_index == tt.abbr_index) break;  // reuse
+    }
+  }
+  if (type_index > 255 || abbr_index > 255) {
+    // No index space (8 bits) available for a new type or abbreviation.
+    return false;
+  }
+  if (type_index == transition_types_.size()) {
+    TransitionType& tt(*transition_types_.emplace(transition_types_.end()));
+    tt.utc_offset = static_cast<std::int_least32_t>(utc_offset);
+    tt.is_dst = is_dst;
+    if (abbr_index == abbreviations_.size()) {
+      abbreviations_.append(abbr);
+      abbreviations_.append(1, '\0');
+    }
+    tt.abbr_index = static_cast<std::uint_least8_t>(abbr_index);
+  }
+  *index = static_cast<std::uint_least8_t>(type_index);
+  return true;
+}
+
 // Use the POSIX-TZ-environment-variable-style string to handle times
 // in years after the last transition stored in the zoneinfo data.
-void TimeZoneInfo::ExtendTransitions(const std::string& name,
-                                     const Header& hdr) {
+bool TimeZoneInfo::ExtendTransitions() {
   extended_ = false;
-  bool extending = !future_spec_.empty();
+  if (future_spec_.empty()) return true;  // last transition prevails
 
   PosixTimeZone posix;
-  if (extending && !ParsePosixSpec(future_spec_, &posix)) {
-    std::clog << name << ": Failed to parse '" << future_spec_ << "'\n";
-    extending = false;
-  }
-
-  if (extending && posix.dst_abbr.empty()) {  // std only
-    // The future specification should match the last/default transition,
-    // and that means that handling the future will fall out naturally.
-    std::uint_fast8_t index = default_transition_type_;
-    if (hdr.timecnt != 0) index = transitions_[hdr.timecnt - 1].type_index;
-    const TransitionType& tt(transition_types_[index]);
-    CheckTransition(name, tt, posix.std_offset, false, posix.std_abbr);
-    extending = false;
-  }
-
-  if (extending && hdr.timecnt < 2) {
-    std::clog << name << ": Too few transitions for POSIX spec\n";
-    extending = false;
-  }
-
-  if (!extending) {
-    // Ensure that there is always a transition in the second half of the
-    // time line (the BIG_BANG transition is in the first half) so that the
-    // signed difference between a civil_second and the civil_second of its
-    // previous transition is always representable, without overflow.
-    const Transition& last(transitions_.back());
-    if (last.unix_time < 0) {
-      const std::uint_fast8_t type_index = last.type_index;
-      Transition& tr(*transitions_.emplace(transitions_.end()));
-      tr.unix_time = 2147483647;  // 2038-01-19T03:14:07+00:00
-      tr.type_index = type_index;
-    }
-    return;  // last transition wins
+  if (!ParsePosixSpec(future_spec_, &posix)) return false;
+
+  // Find transition type for the future std specification.
+  std::uint_least8_t std_ti;
+  if (!GetTransitionType(posix.std_offset, false, posix.std_abbr, &std_ti))
+    return false;
+
+  if (posix.dst_abbr.empty()) {  // std only
+    // The future specification should match the last transition, and
+    // that means that handling the future will fall out naturally.
+    return EquivTransitions(transitions_.back().type_index, std_ti);
   }
 
+  // Find transition type for the future dst specification.
+  std::uint_least8_t dst_ti;
+  if (!GetTransitionType(posix.dst_offset, true, posix.dst_abbr, &dst_ti))
+    return false;
+
   // Extend the transitions for an additional 400 years using the
   // future specification. Years beyond those can be handled by
   // mapping back to a cycle-equivalent year within that range.
-  // zic(8) should probably do this so that we don't have to.
-  // TODO: Reduce the extension by the number of compatible
-  // transitions already in place.
-  transitions_.reserve(hdr.timecnt + 400 * 2 + 1);
-  transitions_.resize(hdr.timecnt + 400 * 2);
+  // We may need two additional transitions for the current year.
+  transitions_.reserve(transitions_.size() + 400 * 2 + 2);
   extended_ = true;
 
-  // The future specification should match the last two transitions,
-  // and those transitions should have different is_dst flags.  Note
-  // that nothing says the UTC offset used by the is_dst transition
-  // must be greater than that used by the !is_dst transition.  (See
-  // Europe/Dublin, for example.)
-  const Transition* tr0 = &transitions_[hdr.timecnt - 1];
-  const Transition* tr1 = &transitions_[hdr.timecnt - 2];
-  const TransitionType* tt0 = &transition_types_[tr0->type_index];
-  const TransitionType* tt1 = &transition_types_[tr1->type_index];
-  const TransitionType& dst(tt0->is_dst ? *tt0 : *tt1);
-  const TransitionType& std(tt0->is_dst ? *tt1 : *tt0);
-  CheckTransition(name, dst, posix.dst_offset, true, posix.dst_abbr);
-  CheckTransition(name, std, posix.std_offset, false, posix.std_abbr);
-
-  // Add the transitions to tr1 and back to tr0 for each extra year.
-  last_year_ = LocalTime(tr0->unix_time, *tt0).cs.year();
+  const Transition& last(transitions_.back());
+  const std::int_fast64_t last_time = last.unix_time;
+  const TransitionType& last_tt(transition_types_[last.type_index]);
+  last_year_ = LocalTime(last_time, last_tt).cs.year();
   bool leap_year = IsLeap(last_year_);
-  const civil_day jan1(last_year_, 1, 1);
-  std::int_fast64_t jan1_time = civil_second(jan1) - civil_second();
-  int jan1_weekday = (static_cast<int>(get_weekday(jan1)) + 1) % 7;
-  Transition* tr = &transitions_[hdr.timecnt];  // next trans to fill
-  if (LocalTime(tr1->unix_time, *tt1).cs.year() != last_year_) {
-    // Add a single extra transition to align to a calendar year.
-    transitions_.resize(transitions_.size() + 1);
-    assert(tr == &transitions_[hdr.timecnt]);  // no reallocation
-    const PosixTransition& pt1(tt0->is_dst ? posix.dst_end : posix.dst_start);
-    std::int_fast64_t tr1_offset = TransOffset(leap_year, jan1_weekday, pt1);
-    tr->unix_time = jan1_time + tr1_offset - tt0->utc_offset;
-    tr++->type_index = tr1->type_index;
-    tr0 = &transitions_[hdr.timecnt];
-    tr1 = &transitions_[hdr.timecnt - 1];
-    tt0 = &transition_types_[tr0->type_index];
-    tt1 = &transition_types_[tr1->type_index];
-  }
-  const PosixTransition& pt1(tt0->is_dst ? posix.dst_end : posix.dst_start);
-  const PosixTransition& pt0(tt0->is_dst ? posix.dst_start : posix.dst_end);
-  for (const year_t limit = last_year_ + 400; last_year_ < limit;) {
-    last_year_ += 1;  // an additional year of generated transitions
+  const civil_second jan1(last_year_);
+  std::int_fast64_t jan1_time = jan1 - civil_second();
+  int jan1_weekday = ToPosixWeekday(get_weekday(jan1));
+
+  Transition dst = {0, dst_ti, civil_second(), civil_second()};
+  Transition std = {0, std_ti, civil_second(), civil_second()};
+  for (const year_t limit = last_year_ + 400;; ++last_year_) {
+    auto dst_trans_off = TransOffset(leap_year, jan1_weekday, posix.dst_start);
+    auto std_trans_off = TransOffset(leap_year, jan1_weekday, posix.dst_end);
+    dst.unix_time = jan1_time + dst_trans_off - posix.std_offset;
+    std.unix_time = jan1_time + std_trans_off - posix.dst_offset;
+    const auto* ta = dst.unix_time < std.unix_time ? &dst : &std;
+    const auto* tb = dst.unix_time < std.unix_time ? &std : &dst;
+    if (last_time < tb->unix_time) {
+      if (last_time < ta->unix_time) transitions_.push_back(*ta);
+      transitions_.push_back(*tb);
+    }
+    if (last_year_ == limit) break;
     jan1_time += kSecsPerYear[leap_year];
     jan1_weekday = (jan1_weekday + kDaysPerYear[leap_year]) % 7;
-    leap_year = !leap_year && IsLeap(last_year_);
-    std::int_fast64_t tr1_offset = TransOffset(leap_year, jan1_weekday, pt1);
-    tr->unix_time = jan1_time + tr1_offset - tt0->utc_offset;
-    tr++->type_index = tr1->type_index;
-    std::int_fast64_t tr0_offset = TransOffset(leap_year, jan1_weekday, pt0);
-    tr->unix_time = jan1_time + tr0_offset - tt1->utc_offset;
-    tr++->type_index = tr0->type_index;
-  }
-  assert(tr == &transitions_[0] + transitions_.size());
+    leap_year = !leap_year && IsLeap(last_year_ + 1);
+  }
+
+  return true;
 }
 
-bool TimeZoneInfo::Load(const std::string& name, ZoneInfoSource* zip) {
+bool TimeZoneInfo::Load(ZoneInfoSource* zip) {
   // Read and validate the header.
   tzhead tzh;
   if (zip->Read(&tzh, sizeof(tzh)) != sizeof(tzh)) return false;
@@ -430,7 +425,7 @@ bool TimeZoneInfo::Load(const std::string& name, ZoneInfoSource* zip) {
   const char* bp = tbuf.data();
 
   // Decode and validate the transitions.
-  transitions_.reserve(hdr.timecnt + 2);  // We might add a couple.
+  transitions_.reserve(hdr.timecnt + 2);
   transitions_.resize(hdr.timecnt);
   for (std::size_t i = 0; i != hdr.timecnt; ++i) {
     transitions_[i].unix_time = (time_len == 4) ? Decode32(bp) : Decode64(bp);
@@ -449,6 +444,7 @@ bool TimeZoneInfo::Load(const std::string& name, ZoneInfoSource* zip) {
   }
 
   // Decode and validate the transition types.
+  transition_types_.reserve(hdr.typecnt + 2);
   transition_types_.resize(hdr.typecnt);
   for (std::size_t i = 0; i != hdr.typecnt; ++i) {
     transition_types_[i].utc_offset =
@@ -475,6 +471,7 @@ bool TimeZoneInfo::Load(const std::string& name, ZoneInfoSource* zip) {
   }
 
   // Copy all the abbreviations.
+  abbreviations_.reserve(hdr.charcnt + 10);
   abbreviations_.assign(bp, hdr.charcnt);
   bp += hdr.charcnt;
 
@@ -525,19 +522,29 @@ bool TimeZoneInfo::Load(const std::string& name, ZoneInfoSource* zip) {
   transitions_.resize(hdr.timecnt);
 
   // Ensure that there is always a transition in the first half of the
-  // time line (the second half is handled in ExtendTransitions()) so that
-  // the signed difference between a civil_second and the civil_second of
-  // its previous transition is always representable, without overflow.
-  // A contemporary zic will usually have already done this for us.
+  // time line (the second half is handled below) so that the signed
+  // difference between a civil_second and the civil_second of its
+  // previous transition is always representable, without overflow.
   if (transitions_.empty() || transitions_.front().unix_time >= 0) {
     Transition& tr(*transitions_.emplace(transitions_.begin()));
-    tr.unix_time = -(1LL << 59);  // see tz/zic.c "BIG_BANG"
+    tr.unix_time = -(1LL << 59);  // -18267312070-10-26T17:01:52+00:00
     tr.type_index = default_transition_type_;
-    hdr.timecnt += 1;
   }
 
   // Extend the transitions using the future specification.
-  ExtendTransitions(name, hdr);
+  if (!ExtendTransitions()) return false;
+
+  // Ensure that there is always a transition in the second half of the
+  // time line (the first half is handled above) so that the signed
+  // difference between a civil_second and the civil_second of its
+  // previous transition is always representable, without overflow.
+  const Transition& last(transitions_.back());
+  if (last.unix_time < 0) {
+    const std::uint_fast8_t type_index = last.type_index;
+    Transition& tr(*transitions_.emplace(transitions_.end()));
+    tr.unix_time = 2147483647;  // 2038-01-19T03:14:07+00:00
+    tr.type_index = type_index;
+  }
 
   // Compute the local civil time for each transition and the preceding
   // second. These will be used for reverse conversions in MakeTime().
@@ -718,12 +725,12 @@ bool TimeZoneInfo::Load(const std::string& name) {
 
   // Find and use a ZoneInfoSource to load the named zone.
   auto zip = cctz_extension::zone_info_source_factory(
-      name, [](const std::string& name) -> std::unique_ptr<ZoneInfoSource> {
-        if (auto zip = FileZoneInfoSource::Open(name)) return zip;
-        if (auto zip = AndroidZoneInfoSource::Open(name)) return zip;
+      name, [](const std::string& n) -> std::unique_ptr<ZoneInfoSource> {
+        if (auto z = FileZoneInfoSource::Open(n)) return z;
+        if (auto z = AndroidZoneInfoSource::Open(n)) return z;
         return nullptr;
       });
-  return zip != nullptr && Load(name, zip.get());
+  return zip != nullptr && Load(zip.get());
 }
 
 // BreakTime() translation for a particular transition type.
@@ -897,8 +904,8 @@ bool TimeZoneInfo::NextTransition(const time_point<seconds>& tp,
   const Transition* begin = &transitions_[0];
   const Transition* end = begin + transitions_.size();
   if (begin->unix_time <= -(1LL << 59)) {
-    // Do not report the BIG_BANG found in recent zoneinfo data as it is
-    // really a sentinel, not a transition.  See tz/zic.c.
+    // Do not report the BIG_BANG found in some zoneinfo data as it is
+    // really a sentinel, not a transition.  See pre-2018f tz/zic.c.
     ++begin;
   }
   std::int_fast64_t unix_time = ToUnixSeconds(tp);
@@ -923,8 +930,8 @@ bool TimeZoneInfo::PrevTransition(const time_point<seconds>& tp,
   const Transition* begin = &transitions_[0];
   const Transition* end = begin + transitions_.size();
   if (begin->unix_time <= -(1LL << 59)) {
-    // Do not report the BIG_BANG found in recent zoneinfo data as it is
-    // really a sentinel, not a transition.  See tz/zic.c.
+    // Do not report the BIG_BANG found in some zoneinfo data as it is
+    // really a sentinel, not a transition.  See pre-2018f tz/zic.c.
     ++begin;
   }
   std::int_fast64_t unix_time = ToUnixSeconds(tp);
diff --git a/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_info.h b/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_info.h
index 2a10c06c77..2467ff559d 100644
--- a/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_info.h
+++ b/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_info.h
@@ -95,15 +95,14 @@ class TimeZoneInfo : public TimeZoneIf {
     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 GetTransitionType(std::int_fast32_t utc_offset, bool is_dst,
+                         const std::string& abbr, std::uint_least8_t* index);
   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 ExtendTransitions();
 
   bool ResetToBuiltinUTC(const seconds& offset);
-  bool Load(const std::string& name, ZoneInfoSource* zip);
+  bool Load(ZoneInfoSource* zip);
 
   // Helpers for BreakTime() and MakeTime().
   time_zone::absolute_lookup LocalTime(std::int_fast64_t unix_time,
diff --git a/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_libc.cc b/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_libc.cc
index 47cf84c663..887dd097c6 100644
--- a/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_libc.cc
+++ b/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_libc.cc
@@ -27,6 +27,12 @@
 #include "absl/time/internal/cctz/include/cctz/civil_time.h"
 #include "absl/time/internal/cctz/include/cctz/time_zone.h"
 
+#if defined(_AIX)
+extern "C" {
+extern long altzone;
+}
+#endif
+
 namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace time_internal {
@@ -44,7 +50,7 @@ auto tm_zone(const std::tm& tm) -> decltype(_tzname[0]) {
   const bool is_dst = tm.tm_isdst > 0;
   return _tzname[is_dst];
 }
-#elif defined(__sun)
+#elif defined(__sun) || defined(_AIX)
 // Uses the globals: 'timezone', 'altzone' and 'tzname'.
 auto tm_gmtoff(const std::tm& tm) -> decltype(timezone) {
   const bool is_dst = tm.tm_isdst > 0;
@@ -153,7 +159,8 @@ std::time_t find_trans(std::time_t lo, std::time_t hi, int offset) {
   std::tm tm;
   while (lo + 1 != hi) {
     const std::time_t mid = lo + (hi - lo) / 2;
-    if (std::tm* tmp = local_time(&mid, &tm)) {
+    std::tm* tmp = local_time(&mid, &tm);
+    if (tmp != nullptr) {
       if (tm_gmtoff(*tmp) == offset) {
         hi = mid;
       } else {
@@ -163,7 +170,8 @@ std::time_t find_trans(std::time_t lo, std::time_t hi, int offset) {
       // If std::tm cannot hold some result we resort to a linear search,
       // ignoring all failed conversions.  Slow, but never really happens.
       while (++lo != hi) {
-        if (std::tm* tmp = local_time(&lo, &tm)) {
+        tmp = local_time(&lo, &tm);
+        if (tmp != nullptr) {
           if (tm_gmtoff(*tmp) == offset) break;
         }
       }
@@ -223,11 +231,10 @@ time_zone::civil_lookup TimeZoneLibC::MakeTime(const civil_second& cs) const {
         civil_second() + ToUnixSeconds(time_point<seconds>::min());
     static const civil_second max_tp_cs =
         civil_second() + ToUnixSeconds(time_point<seconds>::max());
-    const time_point<seconds> tp =
-        (cs < min_tp_cs)
-            ? time_point<seconds>::min()
-            : (cs > max_tp_cs) ? time_point<seconds>::max()
-                               : FromUnixSeconds(cs - civil_second());
+    const time_point<seconds> tp = (cs < min_tp_cs) ? time_point<seconds>::min()
+                                   : (cs > max_tp_cs)
+                                       ? time_point<seconds>::max()
+                                       : FromUnixSeconds(cs - civil_second());
     return {time_zone::civil_lookup::UNIQUE, tp, tp, tp};
   }
 
diff --git a/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_lookup_test.cc b/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_lookup_test.cc
index 8f7ab154fa..9a1a8d6e40 100644
--- a/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_lookup_test.cc
+++ b/third_party/abseil_cpp/absl/time/internal/cctz/src/time_zone_lookup_test.cc
@@ -1004,13 +1004,17 @@ TEST(MakeTime, SysSecondsLimits) {
 #if defined(_WIN32) || defined(_WIN64)
     // localtime_s() and gmtime_s() don't believe in years outside [1970:3000].
 #else
-    const time_zone utc = LoadZone("libc:UTC");
+    const time_zone cut = LoadZone("libc:UTC");
     const year_t max_tm_year = year_t{std::numeric_limits<int>::max()} + 1900;
-    tp = convert(civil_second(max_tm_year, 12, 31, 23, 59, 59), utc);
-    EXPECT_EQ("2147485547-12-31T23:59:59+00:00", format(RFC3339, tp, utc));
+    tp = convert(civil_second(max_tm_year, 12, 31, 23, 59, 59), cut);
+#if defined(__FreeBSD__) || defined(__OpenBSD__)
+    // The BSD gmtime_r() fails on extreme positive tm_year values.
+#else
+    EXPECT_EQ("2147485547-12-31T23:59:59+00:00", format(RFC3339, tp, cut));
+#endif
     const year_t min_tm_year = year_t{std::numeric_limits<int>::min()} + 1900;
-    tp = convert(civil_second(min_tm_year, 1, 1, 0, 0, 0), utc);
-    EXPECT_EQ("-2147481748-01-01T00:00:00+00:00", format(RFC3339, tp, utc));
+    tp = convert(civil_second(min_tm_year, 1, 1, 0, 0, 0), cut);
+    EXPECT_EQ("-2147481748-01-01T00:00:00+00:00", format(RFC3339, tp, cut));
 #endif
   }
 }