Export of internal Abseil changes.

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00d42e3d5433aaf29c2ed293520b2ba178ae8bdb by Greg Falcon <gfalcon@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 238061818

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867a7ca318fac2991ea9a4107dbae3cc9fbf974a by Abseil Team <absl-team@google.com>:

Added a IWYU export pragma when including a standard header for the purpose of aliasing its symbols.

PiperOrigin-RevId: 238022277

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17047745058f2f151cd986ea9f649512542d3876 by Matt Armstrong <marmstrong@google.com>:

Clarify the comment discouraging WrapUnique<T>(x) calls.

PiperOrigin-RevId: 237873803

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3dcb2e4968243d33ca0ce53280c445df50f4a7ec by Samuel Benzaquen <sbenza@google.com>:

Workaround clang bug https://bugs.llvm.org/show_bug.cgi?id=38289

PiperOrigin-RevId: 237873551

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f348d2dc7087a990cbdfb95aa51fd7ff478ae40e by Samuel Benzaquen <sbenza@google.com>:

Reduce minimum capacity to 1.
This reduces memory usage for small tables.
A flat_hash_set<int> of 1 element goes from 92 bytes to 24.
A flat_hash_set<string> of 1 element goes from 512 bytes to 56.

PiperOrigin-RevId: 237859811

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9c8125be5e4e5d22a7bb62bdec8c323338385c1b by Jon Cohen <cohenjon@google.com>:

Bump to CMake 3.5. This is the oldest modern cmake being included by default in most popular OS distributions according to https://repology.org/project/cmake/versions.  Specifically, Ubuntu LTS 16.04 uses cmake 3.5 (https://packages.ubuntu.com/xenial/cmake)

PiperOrigin-RevId: 237859345

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07638d672e0a4dced986a62750cfd8318ed36ffa by Derek Mauro <dmauro@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 237714597
GitOrigin-RevId: 00d42e3d5433aaf29c2ed293520b2ba178ae8bdb
Change-Id: I5faecc45add4a5a774d4f9baf06e5519091f2ccc

absl/time/internal/cctz/src/cctz_benchmark.cc

@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//   http://www.apache.org/licenses/LICENSE-2.0
+//   https://www.apache.org/licenses/LICENSE-2.0
 //
 //   Unless required by applicable law or agreed to in writing, software
 //   distributed under the License is distributed on an "AS IS" BASIS,

absl/time/internal/cctz/src/civil_time_detail.cc

@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//   http://www.apache.org/licenses/LICENSE-2.0
+//   https://www.apache.org/licenses/LICENSE-2.0
 //
 //   Unless required by applicable law or agreed to in writing, software
 //   distributed under the License is distributed on an "AS IS" BASIS,

absl/time/internal/cctz/src/civil_time_test.cc

@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//   http://www.apache.org/licenses/LICENSE-2.0
+//   https://www.apache.org/licenses/LICENSE-2.0
 //
 //   Unless required by applicable law or agreed to in writing, software
 //   distributed under the License is distributed on an "AS IS" BASIS,

absl/time/internal/cctz/src/time_zone_fixed.cc

@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//   http://www.apache.org/licenses/LICENSE-2.0
+//   https://www.apache.org/licenses/LICENSE-2.0
 //
 //   Unless required by applicable law or agreed to in writing, software
 //   distributed under the License is distributed on an "AS IS" BASIS,

absl/time/internal/cctz/src/time_zone_fixed.h

@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//   http://www.apache.org/licenses/LICENSE-2.0
+//   https://www.apache.org/licenses/LICENSE-2.0
 //
 //   Unless required by applicable law or agreed to in writing, software
 //   distributed under the License is distributed on an "AS IS" BASIS,

absl/time/internal/cctz/src/time_zone_format.cc

@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//   http://www.apache.org/licenses/LICENSE-2.0
+//   https://www.apache.org/licenses/LICENSE-2.0
 //
 //   Unless required by applicable law or agreed to in writing, software
 //   distributed under the License is distributed on an "AS IS" BASIS,

absl/time/internal/cctz/src/time_zone_format_test.cc

@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//   http://www.apache.org/licenses/LICENSE-2.0
+//   https://www.apache.org/licenses/LICENSE-2.0
 //
 //   Unless required by applicable law or agreed to in writing, software
 //   distributed under the License is distributed on an "AS IS" BASIS,

absl/time/internal/cctz/src/time_zone_if.cc

@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//   http://www.apache.org/licenses/LICENSE-2.0
+//   https://www.apache.org/licenses/LICENSE-2.0
 //
 //   Unless required by applicable law or agreed to in writing, software
 //   distributed under the License is distributed on an "AS IS" BASIS,

absl/time/internal/cctz/src/time_zone_if.h

@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//   http://www.apache.org/licenses/LICENSE-2.0
+//   https://www.apache.org/licenses/LICENSE-2.0
 //
 //   Unless required by applicable law or agreed to in writing, software
 //   distributed under the License is distributed on an "AS IS" BASIS,

absl/time/internal/cctz/src/time_zone_impl.cc

@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//   http://www.apache.org/licenses/LICENSE-2.0
+//   https://www.apache.org/licenses/LICENSE-2.0
 //
 //   Unless required by applicable law or agreed to in writing, software
 //   distributed under the License is distributed on an "AS IS" BASIS,

absl/time/internal/cctz/src/time_zone_impl.h

@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//   http://www.apache.org/licenses/LICENSE-2.0
+//   https://www.apache.org/licenses/LICENSE-2.0
 //
 //   Unless required by applicable law or agreed to in writing, software
 //   distributed under the License is distributed on an "AS IS" BASIS,

absl/time/internal/cctz/src/time_zone_info.cc

@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//   http://www.apache.org/licenses/LICENSE-2.0
+//   https://www.apache.org/licenses/LICENSE-2.0
 //
 //   Unless required by applicable law or agreed to in writing, software
 //   distributed under the License is distributed on an "AS IS" BASIS,
@@ -25,7 +25,7 @@
 // a grain of salt.
 //
 // For more information see tzfile(5), http://www.iana.org/time-zones, or
-// http://en.wikipedia.org/wiki/Zoneinfo.
+// https://en.wikipedia.org/wiki/Zoneinfo.
 //
 // Note that we assume the proleptic Gregorian calendar and 60-second
 // minutes throughout.

absl/time/internal/cctz/src/time_zone_info.h

@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//   http://www.apache.org/licenses/LICENSE-2.0
+//   https://www.apache.org/licenses/LICENSE-2.0
 //
 //   Unless required by applicable law or agreed to in writing, software
 //   distributed under the License is distributed on an "AS IS" BASIS,

absl/time/internal/cctz/src/time_zone_libc.cc

@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//   http://www.apache.org/licenses/LICENSE-2.0
+//   https://www.apache.org/licenses/LICENSE-2.0
 //
 //   Unless required by applicable law or agreed to in writing, software
 //   distributed under the License is distributed on an "AS IS" BASIS,

absl/time/internal/cctz/src/time_zone_libc.h

@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//   http://www.apache.org/licenses/LICENSE-2.0
+//   https://www.apache.org/licenses/LICENSE-2.0
 //
 //   Unless required by applicable law or agreed to in writing, software
 //   distributed under the License is distributed on an "AS IS" BASIS,

absl/time/internal/cctz/src/time_zone_lookup.cc

@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//   http://www.apache.org/licenses/LICENSE-2.0
+//   https://www.apache.org/licenses/LICENSE-2.0
 //
 //   Unless required by applicable law or agreed to in writing, software
 //   distributed under the License is distributed on an "AS IS" BASIS,
@@ -20,6 +20,11 @@
 #include <dlfcn.h>
 #endif
 #endif
+
+#if defined(__APPLE__)
+#include <CoreFoundation/CFTimeZone.h>
+#endif
+
 #include <cstdlib>
 #include <cstring>
 #include <string>
@@ -121,6 +126,11 @@ time_zone local_time_zone() {
   char* tz_env = nullptr;
 #if defined(_MSC_VER)
   _dupenv_s(&tz_env, nullptr, "TZ");
+#elif defined(__APPLE__)
+  CFTimeZoneRef system_time_zone = CFTimeZoneCopySystem();
+  CFStringRef tz_name = CFTimeZoneGetName(system_time_zone);
+  tz_env = strdup(CFStringGetCStringPtr(tz_name, CFStringGetSystemEncoding()));
+  CFRelease(system_time_zone);
 #else
   tz_env = std::getenv("TZ");
 #endif
@@ -153,6 +163,8 @@ time_zone local_time_zone() {
 #if defined(_MSC_VER)
   free(localtime_env);
   free(tz_env);
+#elif defined(__APPLE__)
+  free(tz_env);
 #endif
 
   time_zone tz;

absl/time/internal/cctz/src/time_zone_lookup_test.cc

@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//   http://www.apache.org/licenses/LICENSE-2.0
+//   https://www.apache.org/licenses/LICENSE-2.0
 //
 //   Unless required by applicable law or agreed to in writing, software
 //   distributed under the License is distributed on an "AS IS" BASIS,

absl/time/internal/cctz/src/time_zone_posix.cc

@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//   http://www.apache.org/licenses/LICENSE-2.0
+//   https://www.apache.org/licenses/LICENSE-2.0
 //
 //   Unless required by applicable law or agreed to in writing, software
 //   distributed under the License is distributed on an "AS IS" BASIS,

absl/time/internal/cctz/src/time_zone_posix.h

@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//   http://www.apache.org/licenses/LICENSE-2.0
+//   https://www.apache.org/licenses/LICENSE-2.0
 //
 //   Unless required by applicable law or agreed to in writing, software
 //   distributed under the License is distributed on an "AS IS" BASIS,

absl/time/internal/cctz/src/zone_info_source.cc

@@ -4,7 +4,7 @@
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
-//   http://www.apache.org/licenses/LICENSE-2.0
+//   https://www.apache.org/licenses/LICENSE-2.0
 //
 //   Unless required by applicable law or agreed to in writing, software
 //   distributed under the License is distributed on an "AS IS" BASIS,