Export of internal Abseil changes.

--
07575526242a8e1275ac4223a3d2822795f46569 by CJ Johnson <johnsoncj@google.com>:

Comment cleanup on InlinedVector

PiperOrigin-RevId: 221322176

--
49a5e643f85e34d53c41f5e6cc33357c55c9115d by Matt Kulukundis <kfm@google.com>:

Internal cleanup

PiperOrigin-RevId: 221309185

--
bb35be87ec9c74244b7d902e7e7d2d33ab139d76 by Abseil Team <absl-team@google.com>:

Fix typo in comment.

PiperOrigin-RevId: 221145354

--
afd4d7c106919708004e06aeea068a57c28aec44 by Derek Mauro <dmauro@google.com>:

Update the debugging log message in CallOnceImpl()

PiperOrigin-RevId: 221103254

--
0b9dace8b88113777bf26a6d38f9bc0bcaf053a1 by Abseil Team <absl-team@google.com>:

Workaround an MSVC 2015 bug in compile-time initialization.

PiperOrigin-RevId: 220871483

--
ea0a3854511ed26beab827e5a5113766b334db86 by Marek Gilbert <mcg@google.com>:

Fix ABSL_HAVE_THREAD_LOCAL when compiling for iOS 8 with Xcode 10.

Xcode 10 has moved the check for thread_local to a link time, so
clang reports __has_feature(cxx_thread_local) but then linking fails
with messages like this:

ld: targeted OS version does not support use of thread local variables
PiperOrigin-RevId: 220815885

--
485b6876c158c3dcf37eb32d7e512242d5d4ecc6 by Greg Falcon <gfalcon@google.com>:

Make the absl::c_set_xxxx() algorithms refuse to compile when passed an unordered collection from std:: or absl::.

These algorithms operate on sorted sequences; passing an unordered container to them is nearly certainly a bug.  This change is technically an API break, but it only breaks incorrect code.

We could try to be more clever and detect unordered collections from other libraries, but false positives will break legal code, and this would constitute an API break Abseil cannot afford.

PiperOrigin-RevId: 220794190

--
c47cff7f9cc70a4c1604eee0131af552f40e46d6 by Jon Cohen <cohenjon@google.com>:

MSVC 2017's STL throws a Structured Exception (not a C++ exception, essentially equivalent to SIGSEGV) when variant::emplace calls a throwing constructor when using the debug multithreaded MSVC runtime DLL.  This manifests in dbg mode in Bazel builds.  Disable tests which trigger this bug.

It's impossible to specifically pull out MSVC 2017 -dbg modes because there's no way for Bazel to know when version of MSVC is being used -- you tell Bazel the directory where the MSVC tools live, not which version of MSVC tools to use.  Thus the best we can do is switch on _DEBUG, which is set whenever the debug runtime is selected with the /MDd build flag, as in Bazel -dbg modes.  See https://msdn.microsoft.com/en-us/library/b0084kay.aspx ctrl-f "_DEBUG"

PiperOrigin-RevId: 220706161

--
43993d4af309d92f4ebff38391dcc245f154ecc7 by Shaindel Schwartz <shaindel@google.com>:

Internal change

PiperOrigin-RevId: 220688429

--
2448802972dcc261af153af464f2b022ef54a2a9 by Abseil Team <absl-team@google.com>:

Speed up operator* for uint128 in WIN64.

PiperOrigin-RevId: 220678790

--
7b376403dd05ba10152fb52e40b29d8af79b58bb by Abseil Team <absl-team@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 220654834

--
ae08af58111c3f838b8d4de25f501c3559c86002 by Abseil Team <absl-team@google.com>:

CMake: Add absl_cc_test function

PiperOrigin-RevId: 220603940
GitOrigin-RevId: 07575526242a8e1275ac4223a3d2822795f46569
Change-Id: Iba7f53eb394c8a9de564582a976793f9bb0596d9

2 files changed, 259 insertions, 41 deletions

diff --git a/absl/time/internal/cctz/src/time_zone_libc.cc b/absl/time/internal/cctz/src/time_zone_libc.cc
index e35fa18b7733..6db519e165cf 100644
--- a/absl/time/internal/cctz/src/time_zone_libc.cc
+++ b/absl/time/internal/cctz/src/time_zone_libc.cc
@@ -20,6 +20,7 @@
 
 #include <chrono>
 #include <ctime>
+#include <limits>
 #include <tuple>
 #include <utility>
 
@@ -85,6 +86,76 @@ OffsetAbbr get_offset_abbr(const T& tm, decltype(&T::__tm_gmtoff) = nullptr,
 #endif  // !defined(__tm_gmtoff) && !defined(__tm_zone)
 #endif
 
+inline std::tm* gm_time(const std::time_t *timep, std::tm *result) {
+#if defined(_WIN32) || defined(_WIN64)
+    return gmtime_s(result, timep) ? nullptr : result;
+#else
+    return gmtime_r(timep, result);
+#endif
+}
+
+inline std::tm* local_time(const std::time_t *timep, std::tm *result) {
+#if defined(_WIN32) || defined(_WIN64)
+    return localtime_s(result, timep) ? nullptr : result;
+#else
+    return localtime_r(timep, result);
+#endif
+}
+
+// Converts a civil second and "dst" flag into a time_t and UTC offset.
+// Returns false if time_t cannot represent the requested civil second.
+// Caller must have already checked that cs.year() will fit into a tm_year.
+bool make_time(const civil_second& cs, int is_dst, std::time_t* t, int* off) {
+  std::tm tm;
+  tm.tm_year = static_cast<int>(cs.year() - year_t{1900});
+  tm.tm_mon = cs.month() - 1;
+  tm.tm_mday = cs.day();
+  tm.tm_hour = cs.hour();
+  tm.tm_min = cs.minute();
+  tm.tm_sec = cs.second();
+  tm.tm_isdst = is_dst;
+  *t = std::mktime(&tm);
+  if (*t == std::time_t{-1}) {
+    std::tm tm2;
+    const std::tm* tmp = local_time(t, &tm2);
+    if (tmp == nullptr || tmp->tm_year != tm.tm_year ||
+        tmp->tm_mon != tm.tm_mon || tmp->tm_mday != tm.tm_mday ||
+        tmp->tm_hour != tm.tm_hour || tmp->tm_min != tm.tm_min ||
+        tmp->tm_sec != tm.tm_sec) {
+      // A true error (not just one second before the epoch).
+      return false;
+    }
+  }
+  *off = get_offset_abbr(tm).first;
+  return true;
+}
+
+// Find the least time_t in [lo:hi] where local time matches offset, given:
+// (1) lo doesn't match, (2) hi does, and (3) there is only one transition.
+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)) {
+      if (get_offset_abbr(*tmp).first == offset) {
+        hi = mid;
+      } else {
+        lo = mid;
+      }
+    } else {
+      // 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)) {
+          if (get_offset_abbr(*tmp).first == offset) break;
+        }
+      }
+      return lo;
+    }
+  }
+  return hi;
+}
+
 }  // namespace
 
 TimeZoneLibC::TimeZoneLibC(const std::string& name)
@@ -93,50 +164,107 @@ TimeZoneLibC::TimeZoneLibC(const std::string& name)
 time_zone::absolute_lookup TimeZoneLibC::BreakTime(
     const time_point<seconds>& tp) const {
   time_zone::absolute_lookup al;
-  std::time_t t = ToUnixSeconds(tp);
+  al.offset = 0;
+  al.is_dst = false;
+  al.abbr = "-00";
+
+  const std::int_fast64_t s = ToUnixSeconds(tp);
+
+  // If std::time_t cannot hold the input we saturate the output.
+  if (s < std::numeric_limits<std::time_t>::min()) {
+    al.cs = civil_second::min();
+    return al;
+  }
+  if (s > std::numeric_limits<std::time_t>::max()) {
+    al.cs = civil_second::max();
+    return al;
+  }
+
+  const std::time_t t = static_cast<std::time_t>(s);
   std::tm tm;
-  if (local_) {
-#if defined(_WIN32) || defined(_WIN64)
-    localtime_s(&tm, &t);
-#else
-    localtime_r(&t, &tm);
-#endif
-    std::tie(al.offset, al.abbr) = get_offset_abbr(tm);
-  } else {
-#if defined(_WIN32) || defined(_WIN64)
-    gmtime_s(&tm, &t);
-#else
-    gmtime_r(&t, &tm);
-#endif
-    al.offset = 0;
-    al.abbr = "UTC";
+  std::tm* tmp = local_ ? local_time(&t, &tm) : gm_time(&t, &tm);
+
+  // If std::tm cannot hold the result we saturate the output.
+  if (tmp == nullptr) {
+    al.cs = (s < 0) ? civil_second::min() : civil_second::max();
+    return al;
   }
-  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;
+
+  const year_t year = tmp->tm_year + year_t{1900};
+  al.cs = civil_second(year, tmp->tm_mon + 1, tmp->tm_mday,
+                       tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
+  std::tie(al.offset, al.abbr) = get_offset_abbr(*tmp);
+  if (!local_) al.abbr = "UTC";  // as expected by cctz
+  al.is_dst = tmp->tm_isdst > 0;
   return al;
 }
 
 time_zone::civil_lookup TimeZoneLibC::MakeTime(const civil_second& cs) const {
-  time_zone::civil_lookup cl;
-  std::time_t t;
-  if (local_) {
-    // Does not handle SKIPPED/AMBIGUOUS or huge years.
-    std::tm tm;
-    tm.tm_year = static_cast<int>(cs.year() - 1900);
-    tm.tm_mon = cs.month() - 1;
-    tm.tm_mday = cs.day();
-    tm.tm_hour = cs.hour();
-    tm.tm_min = cs.minute();
-    tm.tm_sec = cs.second();
-    tm.tm_isdst = -1;
-    t = std::mktime(&tm);
+  if (!local_) {
+    // If time_point<seconds> cannot hold the result we saturate.
+    static const civil_second min_tp_cs =
+        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());
+    return {time_zone::civil_lookup::UNIQUE, tp, tp, tp};
+  }
+
+  // If tm_year cannot hold the requested year we saturate the result.
+  if (cs.year() < 0) {
+    if (cs.year() < std::numeric_limits<int>::min() + year_t{1900}) {
+      const time_point<seconds> tp = time_point<seconds>::min();
+      return {time_zone::civil_lookup::UNIQUE, tp, tp, tp};
+    }
   } else {
-    t = cs - civil_second();
+    if (cs.year() - year_t{1900} > std::numeric_limits<int>::max()) {
+      const time_point<seconds> tp = time_point<seconds>::max();
+      return {time_zone::civil_lookup::UNIQUE, tp, tp, tp};
+    }
+  }
+
+  // We probe with "is_dst" values of 0 and 1 to try to distinguish unique
+  // civil seconds from skipped or repeated ones.  This is not always possible
+  // however, as the "dst" flag does not change over some offset transitions.
+  // We are also subject to the vagaries of mktime() implementations.
+  std::time_t t0, t1;
+  int offset0, offset1;
+  if (make_time(cs, 0, &t0, &offset0) && make_time(cs, 1, &t1, &offset1)) {
+    if (t0 == t1) {
+      // The civil time was singular (pre == trans == post).
+      const time_point<seconds> tp = FromUnixSeconds(t0);
+      return {time_zone::civil_lookup::UNIQUE, tp, tp, tp};
+    }
+
+    if (t0 > t1) {
+      std::swap(t0, t1);
+      std::swap(offset0, offset1);
+    }
+    const std::time_t tt = find_trans(t0, t1, offset1);
+    const time_point<seconds> trans = FromUnixSeconds(tt);
+
+    if (offset0 < offset1) {
+      // The civil time did not exist (pre >= trans > post).
+      const time_point<seconds> pre = FromUnixSeconds(t1);
+      const time_point<seconds> post = FromUnixSeconds(t0);
+      return {time_zone::civil_lookup::SKIPPED, pre, trans, post};
+    }
+
+    // The civil time was ambiguous (pre < trans <= post).
+    const time_point<seconds> pre = FromUnixSeconds(t0);
+    const time_point<seconds> post = FromUnixSeconds(t1);
+    return {time_zone::civil_lookup::REPEATED, pre, trans, post};
   }
-  cl.kind = time_zone::civil_lookup::UNIQUE;
-  cl.pre = cl.trans = cl.post = FromUnixSeconds(t);
-  return cl;
+
+  // make_time() failed somehow so we saturate the result.
+  const time_point<seconds> tp = (cs < civil_second())
+                                     ? time_point<seconds>::min()
+                                     : time_point<seconds>::max();
+  return {time_zone::civil_lookup::UNIQUE, tp, tp, tp};
 }
 
 bool TimeZoneLibC::NextTransition(const time_point<seconds>& tp,
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 f28e7f853b69..e84b9469aa08 100644
--- a/absl/time/internal/cctz/src/time_zone_lookup_test.cc
+++ b/absl/time/internal/cctz/src/time_zone_lookup_test.cc
@@ -16,7 +16,9 @@
 
 #include <chrono>
 #include <cstddef>
+#include <cstdlib>
 #include <future>
+#include <limits>
 #include <string>
 #include <thread>
 #include <vector>
@@ -925,7 +927,7 @@ TEST(MakeTime, Normalization) {
   EXPECT_EQ(tp, convert(civil_second(2009, 2, 13, 18, 30, 90), tz));   // second
 }
 
-// NOTE: Run this with --copt=-ftrapv to detect overflow problems.
+// NOTE: Run this with -ftrapv to detect overflow problems.
 TEST(MakeTime, SysSecondsLimits) {
   const char RFC3339[] =  "%Y-%m-%dT%H:%M:%S%Ez";
   const time_zone utc = utc_time_zone();
@@ -991,19 +993,107 @@ TEST(MakeTime, SysSecondsLimits) {
   tp = convert(civil_second::min(), west);
   EXPECT_EQ(time_point<absl::time_internal::cctz::seconds>::min(), tp);
 
+  // Some similar checks for the "libc" time-zone implementation.
   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.
+    // localtime_s() and gmtime_s() don't believe in years outside [1970:3000].
 #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));
+    const time_zone utc = 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));
+    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));
 #endif
   }
 }
 
+TEST(MakeTime, LocalTimeLibC) {
+  // Checks that cctz and libc agree on transition points in [1970:2037].
+  //
+  // We limit this test case to environments where:
+  //  1) we know how to change the time zone used by localtime()/mktime(),
+  //  2) cctz and localtime()/mktime() will use similar-enough tzdata, and
+  //  3) we have some idea about how mktime() behaves during transitions.
+#if defined(__linux__)
+  const char* const ep = getenv("TZ");
+  std::string tz_name = (ep != nullptr) ? ep : "";
+  for (const char* const* np = kTimeZoneNames; *np != nullptr; ++np) {
+    ASSERT_EQ(0, setenv("TZ", *np, 1));  // change what "localtime" means
+    const auto zi = local_time_zone();
+    const auto lc = LoadZone("libc:localtime");
+    time_zone::civil_transition trans;
+    for (auto tp = zi.lookup(civil_second()).trans;
+         zi.next_transition(tp, &trans);
+         tp = zi.lookup(trans.to).trans) {
+      const auto fcl = zi.lookup(trans.from);
+      const auto tcl = zi.lookup(trans.to);
+      civil_second cs;  // compare cs in zi and lc
+      if (fcl.kind == time_zone::civil_lookup::UNIQUE) {
+        if (tcl.kind == time_zone::civil_lookup::UNIQUE) {
+          // Both unique; must be an is_dst or abbr change.
+          ASSERT_EQ(trans.from, trans.to);
+          const auto trans = fcl.trans;
+          const auto tal = zi.lookup(trans);
+          const auto tprev = trans - absl::time_internal::cctz::seconds(1);
+          const auto pal = zi.lookup(tprev);
+          if (pal.is_dst == tal.is_dst) {
+            ASSERT_STRNE(pal.abbr, tal.abbr);
+          }
+          continue;
+        }
+        ASSERT_EQ(time_zone::civil_lookup::REPEATED, tcl.kind);
+        cs = trans.to;
+      } else {
+        ASSERT_EQ(time_zone::civil_lookup::UNIQUE, tcl.kind);
+        ASSERT_EQ(time_zone::civil_lookup::SKIPPED, fcl.kind);
+        cs = trans.from;
+      }
+      if (cs.year() > 2037) break;  // limit test time (and to 32-bit time_t)
+      const auto cl_zi = zi.lookup(cs);
+      if (zi.lookup(cl_zi.pre).is_dst == zi.lookup(cl_zi.post).is_dst) {
+        // The "libc" implementation cannot correctly classify transitions
+        // that don't change the "tm_isdst" flag.  In Europe/Volgograd, for
+        // example, there is a SKIPPED transition from +03 to +04 with dst=F
+        // on both sides ...
+        //   1540681199 = 2018-10-28 01:59:59 +03:00:00 [dst=F off=10800]
+        //   1540681200 = 2018-10-28 03:00:00 +04:00:00 [dst=F off=14400]
+        // but std::mktime(2018-10-28 02:00:00, tm_isdst=0) fails, unlike,
+        // say, the similar Europe/Chisinau transition from +02 to +03 ...
+        //   1521935999 = 2018-03-25 01:59:59 +02:00:00 [dst=F off=7200]
+        //   1521936000 = 2018-03-25 03:00:00 +03:00:00 [dst=T off=10800]
+        // where std::mktime(2018-03-25 02:00:00, tm_isdst=0) succeeds and
+        // returns 1521936000.
+        continue;
+      }
+      if (cs == civil_second(2037, 10, 4, 2, 0, 0)) {
+        const std::string tzname = *np;
+        if (tzname == "Africa/Casablanca" || tzname == "Africa/El_Aaiun") {
+          // The "libc" implementation gets this transition wrong (at least
+          // until 2018g when it was removed), returning an offset of 3600
+          // instead of 0.  TODO: Revert this when 2018g is ubiquitous.
+          continue;
+        }
+      }
+      const auto cl_lc = lc.lookup(cs);
+      SCOPED_TRACE(testing::Message() << "For " << cs << " in " << *np);
+      EXPECT_EQ(cl_zi.kind, cl_lc.kind);
+      EXPECT_EQ(cl_zi.pre, cl_lc.pre);
+      EXPECT_EQ(cl_zi.trans, cl_lc.trans);
+      EXPECT_EQ(cl_zi.post, cl_lc.post);
+    }
+  }
+  if (ep == nullptr) {
+    ASSERT_EQ(0, unsetenv("TZ"));
+  } else {
+    ASSERT_EQ(0, setenv("TZ", tz_name.c_str(), 1));
+  }
+#endif
+}
+
 TEST(NextTransition, UTC) {
   const auto tz = utc_time_zone();
   time_zone::civil_transition trans;