Export of internal Abseil changes.

--
ac7508120c60dfe689c40929e416b6a486f83ee3 by Gennadiy Rozental <rogeeff@google.com>:

Internal change

PiperOrigin-RevId: 206912089

--
bd709faba88565367b6d337466e6456481b5f3e8 by Matt Calabrese <calabrese@google.com>:

Implement `std::experimental::is_detected` in type_traits internals and move `is_detected_convertible` from variant's internals to type_traits internals. This is in preparation of creating workarounds for broken standard traits.

PiperOrigin-RevId: 206825598

--
0dbddea569370eb9b6348cee172d1874f9046eb4 by Jorg Brown <jorg@google.com>:

Support users who turn on floating-point conversion warnings

PiperOrigin-RevId: 206813209

--
30991f757c8f0100584619d8a9c41897d029f112 by Jorg Brown <jorg@google.com>:

Speed up the absl::Seconds() function for floating-point values, roughly by 4.5x, since
we can take advantage of the fact that we're just taking a floating-point number and
splitting it into its integral and fractional parts.

PiperOrigin-RevId: 206806270

--
6883837176838aa5a517e7a8cb4c99afd24c0d12 by Jon Cohen <cohenjon@google.com>:

Remove the DISABLE_INSTALL from absl_container.  It doesn't do anything.

PiperOrigin-RevId: 206802544

--
92ab14fed06e6dd1f01a0284bd7f95d3e2c0c3d8 by Jon Cohen <cohenjon@google.com>:

Internal change

PiperOrigin-RevId: 206776244

--
17b76c7f364ac562d9e0faeca0320f63aa3fdb85 by Jorg Brown <jorg@google.com>:

Fix absl/strings:numbers_test flakiness due to exceeding the 1-minute timeout

PiperOrigin-RevId: 206763175

--
6637843f2e198b8efd90e5577fbc86bdea43b2cc by Abseil Team <absl-team@google.com>:

Adds templated allocator to absl::FixedArray with corresponding tests

PiperOrigin-RevId: 206354178

--
bced22f81add828c9b4c60eb45554d36c22e2f96 by Abseil Team <absl-team@google.com>:

Adds templated allocator to absl::FixedArray with corresponding tests

PiperOrigin-RevId: 206347377

--
75be14a71d2d5e335812d5b7670120271fb5bd79 by Abseil Team <absl-team@google.com>:

Internal change.

PiperOrigin-RevId: 206326935

--
6929e43f4c7898b1f51e441911a19092a06fbf97 by Abseil Team <absl-team@google.com>:

Adds templated allocator to absl::FixedArray with corresponding tests

PiperOrigin-RevId: 206326368

--
55ae34b75ff029eb267f9519e577bab8a575b487 by Abseil Team <absl-team@google.com>:

Internal change.

PiperOrigin-RevId: 206233448

--
6950a8ccddf35d451eec2d02cd28a797c8b7cf6a by Matt Kulukundis <kfm@google.com>:

Internal change

PiperOrigin-RevId: 206035613
GitOrigin-RevId: ac7508120c60dfe689c40929e416b6a486f83ee3
Change-Id: I675605abbedab6b3ac9aa82195cbd059ff7c82b1

4 files changed, 236 insertions, 68 deletions

diff --git a/absl/time/duration.cc b/absl/time/duration.cc
index c13fa79b..f402137b 100644
--- a/absl/time/duration.cc
+++ b/absl/time/duration.cc
@@ -895,13 +895,10 @@ bool ParseDuration(const std::string& dur_string, Duration* d) {
   *d = dur;
   return true;
 }
-
 bool ParseFlag(const std::string& text, Duration* dst, std::string* ) {
   return ParseDuration(text, dst);
 }
 
-std::string UnparseFlag(Duration d) {
-  return FormatDuration(d);
-}
+std::string UnparseFlag(Duration d) { return FormatDuration(d); }
 
 }  // namespace absl
diff --git a/absl/time/duration_benchmark.cc b/absl/time/duration_benchmark.cc
index 54f89a1f..d5657bd5 100644
--- a/absl/time/duration_benchmark.cc
+++ b/absl/time/duration_benchmark.cc
@@ -27,47 +27,113 @@ namespace {
 //
 
 void BM_Duration_Factory_Nanoseconds(benchmark::State& state) {
+  int64_t i = 0;
   while (state.KeepRunning()) {
-    benchmark::DoNotOptimize(absl::Nanoseconds(1));
+    benchmark::DoNotOptimize(absl::Nanoseconds(i));
+    i += 314159;
   }
 }
 BENCHMARK(BM_Duration_Factory_Nanoseconds);
 
 void BM_Duration_Factory_Microseconds(benchmark::State& state) {
+  int64_t i = 0;
   while (state.KeepRunning()) {
-    benchmark::DoNotOptimize(absl::Microseconds(1));
+    benchmark::DoNotOptimize(absl::Microseconds(i));
+    i += 314;
   }
 }
 BENCHMARK(BM_Duration_Factory_Microseconds);
 
 void BM_Duration_Factory_Milliseconds(benchmark::State& state) {
+  int64_t i = 0;
   while (state.KeepRunning()) {
-    benchmark::DoNotOptimize(absl::Milliseconds(1));
+    benchmark::DoNotOptimize(absl::Milliseconds(i));
+    i += 1;
   }
 }
 BENCHMARK(BM_Duration_Factory_Milliseconds);
 
 void BM_Duration_Factory_Seconds(benchmark::State& state) {
+  int64_t i = 0;
   while (state.KeepRunning()) {
-    benchmark::DoNotOptimize(absl::Seconds(1));
+    benchmark::DoNotOptimize(absl::Seconds(i));
+    i += 1;
   }
 }
 BENCHMARK(BM_Duration_Factory_Seconds);
 
 void BM_Duration_Factory_Minutes(benchmark::State& state) {
+  int64_t i = 0;
   while (state.KeepRunning()) {
-    benchmark::DoNotOptimize(absl::Minutes(1));
+    benchmark::DoNotOptimize(absl::Minutes(i));
+    i += 1;
   }
 }
 BENCHMARK(BM_Duration_Factory_Minutes);
 
 void BM_Duration_Factory_Hours(benchmark::State& state) {
+  int64_t i = 0;
   while (state.KeepRunning()) {
-    benchmark::DoNotOptimize(absl::Hours(1));
+    benchmark::DoNotOptimize(absl::Hours(i));
+    i += 1;
   }
 }
 BENCHMARK(BM_Duration_Factory_Hours);
 
+void BM_Duration_Factory_DoubleNanoseconds(benchmark::State& state) {
+  double d = 1;
+  while (state.KeepRunning()) {
+    benchmark::DoNotOptimize(absl::Nanoseconds(d));
+    d = d * 1.00000001 + 1;
+  }
+}
+BENCHMARK(BM_Duration_Factory_DoubleNanoseconds);
+
+void BM_Duration_Factory_DoubleMicroseconds(benchmark::State& state) {
+  double d = 1e-3;
+  while (state.KeepRunning()) {
+    benchmark::DoNotOptimize(absl::Microseconds(d));
+    d = d * 1.00000001 + 1e-3;
+  }
+}
+BENCHMARK(BM_Duration_Factory_DoubleMicroseconds);
+
+void BM_Duration_Factory_DoubleMilliseconds(benchmark::State& state) {
+  double d = 1e-6;
+  while (state.KeepRunning()) {
+    benchmark::DoNotOptimize(absl::Milliseconds(d));
+    d = d * 1.00000001 + 1e-6;
+  }
+}
+BENCHMARK(BM_Duration_Factory_DoubleMilliseconds);
+
+void BM_Duration_Factory_DoubleSeconds(benchmark::State& state) {
+  double d = 1e-9;
+  while (state.KeepRunning()) {
+    benchmark::DoNotOptimize(absl::Seconds(d));
+    d = d * 1.00000001 + 1e-9;
+  }
+}
+BENCHMARK(BM_Duration_Factory_DoubleSeconds);
+
+void BM_Duration_Factory_DoubleMinutes(benchmark::State& state) {
+  double d = 1e-9;
+  while (state.KeepRunning()) {
+    benchmark::DoNotOptimize(absl::Minutes(d));
+    d = d * 1.00000001 + 1e-9;
+  }
+}
+BENCHMARK(BM_Duration_Factory_DoubleMinutes);
+
+void BM_Duration_Factory_DoubleHours(benchmark::State& state) {
+  double d = 1e-9;
+  while (state.KeepRunning()) {
+    benchmark::DoNotOptimize(absl::Hours(d));
+    d = d * 1.00000001 + 1e-9;
+  }
+}
+BENCHMARK(BM_Duration_Factory_DoubleHours);
+
 //
 // Arithmetic
 //
diff --git a/absl/time/duration_test.cc b/absl/time/duration_test.cc
index 704684ed..7ae25dc6 100644
--- a/absl/time/duration_test.cc
+++ b/absl/time/duration_test.cc
@@ -16,7 +16,9 @@
 #include <cmath>
 #include <cstdint>
 #include <ctime>
+#include <iomanip>
 #include <limits>
+#include <random>
 #include <string>
 
 #include "gmock/gmock.h"
@@ -105,22 +107,22 @@ TEST(Duration, Factories) {
 }
 
 TEST(Duration, ToConversion) {
-#define TEST_DURATION_CONVERSION(UNIT)                              \
-  do {                                                              \
-    const absl::Duration d = absl::UNIT(1.5);                       \
-    const absl::Duration z = absl::ZeroDuration();                  \
-    const absl::Duration inf = absl::InfiniteDuration();            \
-    const double dbl_inf = std::numeric_limits<double>::infinity(); \
-    EXPECT_EQ(kint64min, absl::ToInt64##UNIT(-inf));                \
-    EXPECT_EQ(-1, absl::ToInt64##UNIT(-d));                         \
-    EXPECT_EQ(0, absl::ToInt64##UNIT(z));                           \
-    EXPECT_EQ(1, absl::ToInt64##UNIT(d));                           \
-    EXPECT_EQ(kint64max, absl::ToInt64##UNIT(inf));                 \
-    EXPECT_EQ(-dbl_inf, absl::ToDouble##UNIT(-inf));                \
-    EXPECT_EQ(-1.5, absl::ToDouble##UNIT(-d));                      \
-    EXPECT_EQ(0, absl::ToDouble##UNIT(z));                          \
-    EXPECT_EQ(1.5, absl::ToDouble##UNIT(d));                        \
-    EXPECT_EQ(dbl_inf, absl::ToDouble##UNIT(inf));                  \
+#define TEST_DURATION_CONVERSION(UNIT)                                  \
+  do {                                                                  \
+    const absl::Duration d = absl::UNIT(1.5);                           \
+    constexpr absl::Duration z = absl::ZeroDuration();                  \
+    constexpr absl::Duration inf = absl::InfiniteDuration();            \
+    constexpr double dbl_inf = std::numeric_limits<double>::infinity(); \
+    EXPECT_EQ(kint64min, absl::ToInt64##UNIT(-inf));                    \
+    EXPECT_EQ(-1, absl::ToInt64##UNIT(-d));                             \
+    EXPECT_EQ(0, absl::ToInt64##UNIT(z));                               \
+    EXPECT_EQ(1, absl::ToInt64##UNIT(d));                               \
+    EXPECT_EQ(kint64max, absl::ToInt64##UNIT(inf));                     \
+    EXPECT_EQ(-dbl_inf, absl::ToDouble##UNIT(-inf));                    \
+    EXPECT_EQ(-1.5, absl::ToDouble##UNIT(-d));                          \
+    EXPECT_EQ(0, absl::ToDouble##UNIT(z));                              \
+    EXPECT_EQ(1.5, absl::ToDouble##UNIT(d));                            \
+    EXPECT_EQ(dbl_inf, absl::ToDouble##UNIT(inf));                      \
   } while (0)
 
   TEST_DURATION_CONVERSION(Nanoseconds);
@@ -1284,6 +1286,16 @@ TEST(Duration, SmallConversions) {
   EXPECT_EQ(absl::Nanoseconds(1), absl::Seconds(0.875e-9));
   EXPECT_EQ(absl::Nanoseconds(1), absl::Seconds(1.000e-9));
 
+  EXPECT_EQ(absl::ZeroDuration(), absl::Seconds(-0.124999999e-9));
+  EXPECT_EQ(-absl::Nanoseconds(1) / 4, absl::Seconds(-0.125e-9));
+  EXPECT_EQ(-absl::Nanoseconds(1) / 4, absl::Seconds(-0.250e-9));
+  EXPECT_EQ(-absl::Nanoseconds(1) / 2, absl::Seconds(-0.375e-9));
+  EXPECT_EQ(-absl::Nanoseconds(1) / 2, absl::Seconds(-0.500e-9));
+  EXPECT_EQ(-absl::Nanoseconds(3) / 4, absl::Seconds(-0.625e-9));
+  EXPECT_EQ(-absl::Nanoseconds(3) / 4, absl::Seconds(-0.750e-9));
+  EXPECT_EQ(-absl::Nanoseconds(1), absl::Seconds(-0.875e-9));
+  EXPECT_EQ(-absl::Nanoseconds(1), absl::Seconds(-1.000e-9));
+
   timespec ts;
   ts.tv_sec = 0;
   ts.tv_nsec = 0;
@@ -1313,6 +1325,86 @@ TEST(Duration, SmallConversions) {
   EXPECT_THAT(ToTimeval(absl::Nanoseconds(2000)), TimevalMatcher(tv));
 }
 
+void VerifySameAsMul(double time_as_seconds, int* const misses) {
+  auto direct_seconds = absl::Seconds(time_as_seconds);
+  auto mul_by_one_second = time_as_seconds * absl::Seconds(1);
+  if (direct_seconds != mul_by_one_second) {
+    if (*misses > 10) return;
+    ASSERT_LE(++(*misses), 10) << "Too many errors, not reporting more.";
+    EXPECT_EQ(direct_seconds, mul_by_one_second)
+        << "given double time_as_seconds = " << std::setprecision(17)
+        << time_as_seconds;
+  }
+}
+
+// For a variety of interesting durations, we find the exact point
+// where one double converts to that duration, and the very next double
+// converts to the next duration.  For both of those points, verify that
+// Seconds(point) returns the same duration as point * Seconds(1.0)
+TEST(Duration, ToDoubleSecondsCheckEdgeCases) {
+  constexpr uint32_t kTicksPerSecond = absl::time_internal::kTicksPerSecond;
+  constexpr auto duration_tick = absl::time_internal::MakeDuration(0, 1u);
+  int misses = 0;
+  for (int64_t seconds = 0; seconds < 99; ++seconds) {
+    uint32_t tick_vals[] = {0, +999, +999999, +999999999, kTicksPerSecond - 1,
+                            0, 1000, 1000000, 1000000000, kTicksPerSecond,
+                            1, 1001, 1000001, 1000000001, kTicksPerSecond + 1,
+                            2, 1002, 1000002, 1000000002, kTicksPerSecond + 2,
+                            3, 1003, 1000003, 1000000003, kTicksPerSecond + 3,
+                            4, 1004, 1000004, 1000000004, kTicksPerSecond + 4,
+                            5, 6,    7,       8,          9};
+    for (uint32_t ticks : tick_vals) {
+      absl::Duration s_plus_t = absl::Seconds(seconds) + ticks * duration_tick;
+      for (absl::Duration d : {s_plus_t, -s_plus_t}) {
+        absl::Duration after_d = d + duration_tick;
+        EXPECT_NE(d, after_d);
+        EXPECT_EQ(after_d - d, duration_tick);
+
+        double low_edge = ToDoubleSeconds(d);
+        EXPECT_EQ(d, absl::Seconds(low_edge));
+
+        double high_edge = ToDoubleSeconds(after_d);
+        EXPECT_EQ(after_d, absl::Seconds(high_edge));
+
+        for (;;) {
+          double midpoint = low_edge + (high_edge - low_edge) / 2;
+          if (midpoint == low_edge || midpoint == high_edge) break;
+          absl::Duration mid_duration = absl::Seconds(midpoint);
+          if (mid_duration == d) {
+            low_edge = midpoint;
+          } else {
+            EXPECT_EQ(mid_duration, after_d);
+            high_edge = midpoint;
+          }
+        }
+        // Now low_edge is the highest double that converts to Duration d,
+        // and high_edge is the lowest double that converts to Duration after_d.
+        VerifySameAsMul(low_edge, &misses);
+        VerifySameAsMul(high_edge, &misses);
+      }
+    }
+  }
+}
+
+TEST(Duration, ToDoubleSecondsCheckRandom) {
+  std::random_device rd;
+  std::seed_seq seed({rd(), rd(), rd(), rd(), rd(), rd(), rd(), rd()});
+  std::mt19937_64 gen(seed);
+  // We want doubles distributed from 1/8ns up to 2^63, where
+  // as many values are tested from 1ns to 2ns as from 1sec to 2sec,
+  // so even distribute along a log-scale of those values, and
+  // exponentiate before using them.  (9.223377e+18 is just slightly
+  // out of bounds for absl::Duration.)
+  std::uniform_real_distribution<double> uniform(std::log(0.125e-9),
+                                                 std::log(9.223377e+18));
+  int misses = 0;
+  for (int i = 0; i < 1000000; ++i) {
+    double d = std::exp(uniform(gen));
+    VerifySameAsMul(d, &misses);
+    VerifySameAsMul(-d, &misses);
+  }
+}
+
 TEST(Duration, ConversionSaturation) {
   absl::Duration d;
 
diff --git a/absl/time/time.h b/absl/time/time.h
index 880fc783..c41cb89c 100644
--- a/absl/time/time.h
+++ b/absl/time/time.h
@@ -81,6 +81,7 @@ constexpr int64_t GetRepHi(Duration d);
 constexpr uint32_t GetRepLo(Duration d);
 constexpr Duration MakeDuration(int64_t hi, uint32_t lo);
 constexpr Duration MakeDuration(int64_t hi, int64_t lo);
+inline Duration MakePosDoubleDuration(double n);
 constexpr int64_t kTicksPerNanosecond = 4;
 constexpr int64_t kTicksPerSecond = 1000 * 1000 * 1000 * kTicksPerNanosecond;
 template <std::intmax_t N>
@@ -295,6 +296,39 @@ Duration Floor(Duration d, Duration unit);
 //   absl::Duration c = absl::Ceil(d, absl::Microseconds(1));   // 123457us
 Duration Ceil(Duration d, Duration unit);
 
+// InfiniteDuration()
+//
+// Returns an infinite `Duration`.  To get a `Duration` representing negative
+// infinity, use `-InfiniteDuration()`.
+//
+// Duration arithmetic overflows to +/- infinity and saturates. In general,
+// arithmetic with `Duration` infinities is similar to IEEE 754 infinities
+// except where IEEE 754 NaN would be involved, in which case +/-
+// `InfiniteDuration()` is used in place of a "nan" Duration.
+//
+// Examples:
+//
+//   constexpr absl::Duration inf = absl::InfiniteDuration();
+//   const absl::Duration d = ... any finite duration ...
+//
+//   inf == inf + inf
+//   inf == inf + d
+//   inf == inf - inf
+//   -inf == d - inf
+//
+//   inf == d * 1e100
+//   inf == inf / 2
+//   0 == d / inf
+//   INT64_MAX == inf / d
+//
+//   // Division by zero returns infinity, or INT64_MIN/MAX where appropriate.
+//   inf == d / 0
+//   INT64_MAX == d / absl::ZeroDuration()
+//
+// The examples involving the `/` operator above also apply to `IDivDuration()`
+// and `FDivDuration()`.
+constexpr Duration InfiniteDuration();
+
 // Nanoseconds()
 // Microseconds()
 // Milliseconds()
@@ -344,7 +378,13 @@ Duration Milliseconds(T n) {
 }
 template <typename T, time_internal::EnableIfFloat<T> = 0>
 Duration Seconds(T n) {
-  return n * Seconds(1);
+  if (n >= 0) {
+    if (n >= std::numeric_limits<int64_t>::max()) return InfiniteDuration();
+    return time_internal::MakePosDoubleDuration(n);
+  } else {
+    if (n <= std::numeric_limits<int64_t>::min()) return -InfiniteDuration();
+    return -time_internal::MakePosDoubleDuration(-n);
+  }
 }
 template <typename T, time_internal::EnableIfFloat<T> = 0>
 Duration Minutes(T n) {
@@ -439,39 +479,6 @@ std::chrono::seconds ToChronoSeconds(Duration d);
 std::chrono::minutes ToChronoMinutes(Duration d);
 std::chrono::hours ToChronoHours(Duration d);
 
-// InfiniteDuration()
-//
-// Returns an infinite `Duration`.  To get a `Duration` representing negative
-// infinity, use `-InfiniteDuration()`.
-//
-// Duration arithmetic overflows to +/- infinity and saturates. In general,
-// arithmetic with `Duration` infinities is similar to IEEE 754 infinities
-// except where IEEE 754 NaN would be involved, in which case +/-
-// `InfiniteDuration()` is used in place of a "nan" Duration.
-//
-// Examples:
-//
-//   constexpr absl::Duration inf = absl::InfiniteDuration();
-//   const absl::Duration d = ... any finite duration ...
-//
-//   inf == inf + inf
-//   inf == inf + d
-//   inf == inf - inf
-//   -inf == d - inf
-//
-//   inf == d * 1e100
-//   inf == inf / 2
-//   0 == d / inf
-//   INT64_MAX == inf / d
-//
-//   // Division by zero returns infinity, or INT64_MIN/MAX where appropriate.
-//   inf == d / 0
-//   INT64_MAX == d / absl::ZeroDuration()
-//
-// The examples involving the `/` operator above also apply to `IDivDuration()`
-// and `FDivDuration()`.
-constexpr Duration InfiniteDuration();
-
 // FormatDuration()
 //
 // Returns a std::string representing the duration in the form "72h3m0.5s".
@@ -492,12 +499,9 @@ inline std::ostream& operator<<(std::ostream& os, Duration d) {
 // `ZeroDuration()`.  Parses "inf" and "-inf" as +/- `InfiniteDuration()`.
 bool ParseDuration(const std::string& dur_string, Duration* d);
 
-// ParseFlag()
-//
+// Support for flag values of type Duration. Duration flags must be specified
+// in a format that is valid input for absl::ParseDuration().
 bool ParseFlag(const std::string& text, Duration* dst, std::string* error);
-
-// UnparseFlag()
-//
 std::string UnparseFlag(Duration d);
 
 // Time
@@ -991,9 +995,6 @@ bool ParseTime(const std::string& format, const std::string& input, Time* time,
 bool ParseTime(const std::string& format, const std::string& input, TimeZone tz,
                Time* time, std::string* err);
 
-// ParseFlag()
-// UnparseFlag()
-//
 // Support for flag values of type Time. Time flags must be specified in a
 // format that matches absl::RFC3339_full. For example:
 //
@@ -1114,6 +1115,18 @@ constexpr Duration MakeDuration(int64_t hi, int64_t lo) {
   return MakeDuration(hi, static_cast<uint32_t>(lo));
 }
 
+// Make a Duration value from a floating-point number, as long as that number
+// is in the range [ 0 .. numeric_limits<int64_t>::max ), that is, as long as
+// it's positive and can be converted to int64_t without risk of UB.
+inline Duration MakePosDoubleDuration(double n) {
+  const int64_t int_secs = static_cast<int64_t>(n);
+  const uint32_t ticks =
+      static_cast<uint32_t>((n - int_secs) * kTicksPerSecond + 0.5);
+  return ticks < kTicksPerSecond
+             ? MakeDuration(int_secs, ticks)
+             : MakeDuration(int_secs + 1, ticks - kTicksPerSecond);
+}
+
 // Creates a normalized Duration from an almost-normalized (sec,ticks)
 // pair. sec may be positive or negative.  ticks must be in the range
 // -kTicksPerSecond < *ticks < kTicksPerSecond.  If ticks is negative it