// Copyright 2005, Google Inc.
	// All rights reserved.
	//
	// Redistribution and use in source and binary forms, with or without
	// modification, are permitted provided that the following conditions are
	// met:
	//
	//     * Redistributions of source code must retain the above copyright
	// notice, this list of conditions and the following disclaimer.
	//     * Redistributions in binary form must reproduce the above
	// copyright notice, this list of conditions and the following disclaimer
	// in the documentation and/or other materials provided with the
	// distribution.
	//     * Neither the name of Google Inc. nor the names of its
	// contributors may be used to endorse or promote products derived from
	// this software without specific prior written permission.
	//
	// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	//
	// Low-level types and utilities for porting Google Test to various
	// platforms.  All macros ending with _ and symbols defined in an
	// internal namespace are subject to change without notice.  Code
	// outside Google Test MUST NOT USE THEM DIRECTLY.  Macros that don't
	// end with _ are part of Google Test's public API and can be used by
	// code outside Google Test.
	//
	// This file is fundamental to Google Test.  All other Google Test source
	// files are expected to #include this.  Therefore, it cannot #include
	// any other Google Test header.
	
	// GOOGLETEST_CM0001 DO NOT DELETE
	
	#ifndef GTEST_INCLUDE_GTEST_INTERNAL_GTEST_PORT_H_
	#define GTEST_INCLUDE_GTEST_INTERNAL_GTEST_PORT_H_
	
	// Environment-describing macros
	// -----------------------------
	//
	// Google Test can be used in many different environments.  Macros in
	// this section tell Google Test what kind of environment it is being
	// used in, such that Google Test can provide environment-specific
	// features and implementations.
	//
	// Google Test tries to automatically detect the properties of its
	// environment, so users usually don't need to worry about these
	// macros.  However, the automatic detection is not perfect.
	// Sometimes it's necessary for a user to define some of the following
	// macros in the build script to override Google Test's decisions.
	//
	// If the user doesn't define a macro in the list, Google Test will
	// provide a default definition.  After this header is #included, all
	// macros in this list will be defined to either 1 or 0.
	//
	// Notes to maintainers:
	//   - Each macro here is a user-tweakable knob; do not grow the list
	//     lightly.
	//   - Use #if to key off these macros.  Don't use #ifdef or "#if
	//     defined(...)", which will not work as these macros are ALWAYS
	//     defined.
	//
	//   GTEST_HAS_CLONE          - Define it to 1/0 to indicate that clone(2)
	//                              is/isn't available.
	//   GTEST_HAS_EXCEPTIONS     - Define it to 1/0 to indicate that exceptions
	//                              are enabled.
	//   GTEST_HAS_POSIX_RE       - Define it to 1/0 to indicate that POSIX regular
	//                              expressions are/aren't available.
	//   GTEST_HAS_PTHREAD        - Define it to 1/0 to indicate that <pthread.h>
	//                              is/isn't available.
	//   GTEST_HAS_RTTI           - Define it to 1/0 to indicate that RTTI is/isn't
	//                              enabled.
	//   GTEST_HAS_STD_WSTRING    - Define it to 1/0 to indicate that
	//                              std::wstring does/doesn't work (Google Test can
	//                              be used where std::wstring is unavailable).
	//   GTEST_HAS_SEH            - Define it to 1/0 to indicate whether the
	//                              compiler supports Microsoft's "Structured
	//                              Exception Handling".
	//   GTEST_HAS_STREAM_REDIRECTION
	//                            - Define it to 1/0 to indicate whether the
	//                              platform supports I/O stream redirection using
	//                              dup() and dup2().
	//   GTEST_LINKED_AS_SHARED_LIBRARY
	//                            - Define to 1 when compiling tests that use
	//                              Google Test as a shared library (known as
	//                              DLL on Windows).
	//   GTEST_CREATE_SHARED_LIBRARY
	//                            - Define to 1 when compiling Google Test itself
	//                              as a shared library.
	//   GTEST_DEFAULT_DEATH_TEST_STYLE
	//                            - The default value of --gtest_death_test_style.
	//                              The legacy default has been "fast" in the open
	//                              source version since 2008. The recommended value
	//                              is "threadsafe", and can be set in
	//                              custom/gtest-port.h.
	
	// Platform-indicating macros
	// --------------------------
	//
	// Macros indicating the platform on which Google Test is being used
	// (a macro is defined to 1 if compiled on the given platform;
	// otherwise UNDEFINED -- it's never defined to 0.).  Google Test
	// defines these macros automatically.  Code outside Google Test MUST
	// NOT define them.
	//
	//   GTEST_OS_AIX      - IBM AIX
	//   GTEST_OS_CYGWIN   - Cygwin
	//   GTEST_OS_DRAGONFLY - DragonFlyBSD
	//   GTEST_OS_FREEBSD  - FreeBSD
	//   GTEST_OS_FUCHSIA  - Fuchsia
	//   GTEST_OS_GNU_KFREEBSD - GNU/kFreeBSD
	//   GTEST_OS_HAIKU    - Haiku
	//   GTEST_OS_HPUX     - HP-UX
	//   GTEST_OS_LINUX    - Linux
	//     GTEST_OS_LINUX_ANDROID - Google Android
	//   GTEST_OS_MAC      - Mac OS X
	//     GTEST_OS_IOS    - iOS
	//   GTEST_OS_NACL     - Google Native Client (NaCl)
	//   GTEST_OS_NETBSD   - NetBSD
	//   GTEST_OS_OPENBSD  - OpenBSD
	//   GTEST_OS_OS2      - OS/2
	//   GTEST_OS_QNX      - QNX
	//   GTEST_OS_SOLARIS  - Sun Solaris
	//   GTEST_OS_WINDOWS  - Windows (Desktop, MinGW, or Mobile)
	//     GTEST_OS_WINDOWS_DESKTOP  - Windows Desktop
	//     GTEST_OS_WINDOWS_MINGW    - MinGW
	//     GTEST_OS_WINDOWS_MOBILE   - Windows Mobile
	//     GTEST_OS_WINDOWS_PHONE    - Windows Phone
	//     GTEST_OS_WINDOWS_RT       - Windows Store App/WinRT
	//   GTEST_OS_ZOS      - z/OS
	//
	// Among the platforms, Cygwin, Linux, Mac OS X, and Windows have the
	// most stable support.  Since core members of the Google Test project
	// don't have access to other platforms, support for them may be less
	// stable.  If you notice any problems on your platform, please notify
	// googletestframework@googlegroups.com (patches for fixing them are
	// even more welcome!).
	//
	// It is possible that none of the GTEST_OS_* macros are defined.
	
	// Feature-indicating macros
	// -------------------------
	//
	// Macros indicating which Google Test features are available (a macro
	// is defined to 1 if the corresponding feature is supported;
	// otherwise UNDEFINED -- it's never defined to 0.).  Google Test
	// defines these macros automatically.  Code outside Google Test MUST
	// NOT define them.
	//
	// These macros are public so that portable tests can be written.
	// Such tests typically surround code using a feature with an #if
	// which controls that code.  For example:
	//
	// #if GTEST_HAS_DEATH_TEST
	//   EXPECT_DEATH(DoSomethingDeadly());
	// #endif
	//
	//   GTEST_HAS_DEATH_TEST   - death tests
	//   GTEST_HAS_TYPED_TEST   - typed tests
	//   GTEST_HAS_TYPED_TEST_P - type-parameterized tests
	//   GTEST_IS_THREADSAFE    - Google Test is thread-safe.
	//   GOOGLETEST_CM0007 DO NOT DELETE
	//   GTEST_USES_POSIX_RE    - enhanced POSIX regex is used. Do not confuse with
	//                            GTEST_HAS_POSIX_RE (see above) which users can
	//                            define themselves.
	//   GTEST_USES_SIMPLE_RE   - our own simple regex is used;
	//                            the above RE\b(s) are mutually exclusive.
	
	// Misc public macros
	// ------------------
	//
	//   GTEST_FLAG(flag_name)  - references the variable corresponding to
	//                            the given Google Test flag.
	
	// Internal utilities
	// ------------------
	//
	// The following macros and utilities are for Google Test's INTERNAL
	// use only.  Code outside Google Test MUST NOT USE THEM DIRECTLY.
	//
	// Macros for basic C++ coding:
	//   GTEST_AMBIGUOUS_ELSE_BLOCKER_ - for disabling a gcc warning.
	//   GTEST_ATTRIBUTE_UNUSED_  - declares that a class' instances or a
	//                              variable don't have to be used.
	//   GTEST_DISALLOW_ASSIGN_   - disables operator=.
	//   GTEST_DISALLOW_COPY_AND_ASSIGN_ - disables copy ctor and operator=.
	//   GTEST_MUST_USE_RESULT_   - declares that a function's result must be used.
	//   GTEST_INTENTIONAL_CONST_COND_PUSH_ - start code section where MSVC C4127 is
	//                                        suppressed (constant conditional).
	//   GTEST_INTENTIONAL_CONST_COND_POP_  - finish code section where MSVC C4127
	//                                        is suppressed.
	//
	// Synchronization:
	//   Mutex, MutexLock, ThreadLocal, GetThreadCount()
	//                            - synchronization primitives.
	//
	// Template meta programming:
	//   IteratorTraits - partial implementation of std::iterator_traits, which
	//                    is not available in libCstd when compiled with Sun C++.
	//
	//
	// Regular expressions:
	//   RE             - a simple regular expression class using the POSIX
	//                    Extended Regular Expression syntax on UNIX-like platforms
	//                    GOOGLETEST_CM0008 DO NOT DELETE
	//                    or a reduced regular exception syntax on other
	//                    platforms, including Windows.
	// Logging:
	//   GTEST_LOG_()   - logs messages at the specified severity level.
	//   LogToStderr()  - directs all log messages to stderr.
	//   FlushInfoLog() - flushes informational log messages.
	//
	// Stdout and stderr capturing:
	//   CaptureStdout()     - starts capturing stdout.
	//   GetCapturedStdout() - stops capturing stdout and returns the captured
	//                         string.
	//   CaptureStderr()     - starts capturing stderr.
	//   GetCapturedStderr() - stops capturing stderr and returns the captured
	//                         string.
	//
	// Integer types:
	//   TypeWithSize   - maps an integer to a int type.
	//   Int32, UInt32, Int64, UInt64, TimeInMillis
	//                  - integers of known sizes.
	//   BiggestInt     - the biggest signed integer type.
	//
	// Command-line utilities:
	//   GTEST_DECLARE_*()  - declares a flag.
	//   GTEST_DEFINE_*()   - defines a flag.
	//   GetInjectableArgvs() - returns the command line as a vector of strings.
	//
	// Environment variable utilities:
	//   GetEnv()             - gets the value of an environment variable.
	//   BoolFromGTestEnv()   - parses a bool environment variable.
	//   Int32FromGTestEnv()  - parses an Int32 environment variable.
	//   StringFromGTestEnv() - parses a string environment variable.
	//
	// Deprecation warnings:
	//   GTEST_INTERNAL_DEPRECATED(message) - attribute marking a function as
	//                                        deprecated; calling a marked function
	//                                        should generate a compiler warning
	
	#include <ctype.h>   // for isspace, etc
	#include <stddef.h>  // for ptrdiff_t
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <memory>
	#include <type_traits>
	
	#ifndef _WIN32_WCE
	# include <sys/types.h>
	# include <sys/stat.h>
	#endif  // !_WIN32_WCE
	
	#if defined __APPLE__
	# include <AvailabilityMacros.h>
	# include <TargetConditionals.h>
	#endif
	
	#include <algorithm>  // NOLINT
	#include <iostream>   // NOLINT
	#include <sstream>    // NOLINT
	#include <string>     // NOLINT
	#include <tuple>
	#include <utility>
	#include <vector>  // NOLINT
	
	#include "gtest/internal/gtest-port-arch.h"
	#include "gtest/internal/custom/gtest-port.h"
	
	#if !defined(GTEST_DEV_EMAIL_)
	# define GTEST_DEV_EMAIL_ "googletestframework@@googlegroups.com"
	# define GTEST_FLAG_PREFIX_ "gtest_"
	# define GTEST_FLAG_PREFIX_DASH_ "gtest-"
	# define GTEST_FLAG_PREFIX_UPPER_ "GTEST_"
	# define GTEST_NAME_ "Google Test"
	# define GTEST_PROJECT_URL_ "https://github.com/google/googletest/"
	#endif  // !defined(GTEST_DEV_EMAIL_)
	
	#if !defined(GTEST_INIT_GOOGLE_TEST_NAME_)
	# define GTEST_INIT_GOOGLE_TEST_NAME_ "testing::InitGoogleTest"
	#endif  // !defined(GTEST_INIT_GOOGLE_TEST_NAME_)
	
	// Determines the version of gcc that is used to compile this.
	#ifdef __GNUC__
	// 40302 means version 4.3.2.
	# define GTEST_GCC_VER_ \
	    (__GNUC__*10000 + __GNUC_MINOR__*100 + __GNUC_PATCHLEVEL__)
	#endif  // __GNUC__
	
	// Macros for disabling Microsoft Visual C++ warnings.
	//
	//   GTEST_DISABLE_MSC_WARNINGS_PUSH_(4800 4385)
	//   /* code that triggers warnings C4800 and C4385 */
	//   GTEST_DISABLE_MSC_WARNINGS_POP_()
	#if defined(_MSC_VER)
	# define GTEST_DISABLE_MSC_WARNINGS_PUSH_(warnings) \
	    __pragma(warning(push))                        \
	    __pragma(warning(disable: warnings))
	# define GTEST_DISABLE_MSC_WARNINGS_POP_()          \
	    __pragma(warning(pop))
	#else
	// Not all compilers are MSVC
	# define GTEST_DISABLE_MSC_WARNINGS_PUSH_(warnings)
	# define GTEST_DISABLE_MSC_WARNINGS_POP_()
	#endif
	
	// Clang on Windows does not understand MSVC's pragma warning.
	// We need clang-specific way to disable function deprecation warning.
	#ifdef __clang__
	# define GTEST_DISABLE_MSC_DEPRECATED_PUSH_()                         \
	    _Pragma("clang diagnostic push")                                  \
	    _Pragma("clang diagnostic ignored \"-Wdeprecated-declarations\"") \
	    _Pragma("clang diagnostic ignored \"-Wdeprecated-implementations\"")
	#define GTEST_DISABLE_MSC_DEPRECATED_POP_() \
	    _Pragma("clang diagnostic pop")
	#else
	# define GTEST_DISABLE_MSC_DEPRECATED_PUSH_() \
	    GTEST_DISABLE_MSC_WARNINGS_PUSH_(4996)
	# define GTEST_DISABLE_MSC_DEPRECATED_POP_() \
	    GTEST_DISABLE_MSC_WARNINGS_POP_()
	#endif
	
	// Brings in definitions for functions used in the testing::internal::posix
	// namespace (read, write, close, chdir, isatty, stat). We do not currently
	// use them on Windows Mobile.
	#if GTEST_OS_WINDOWS
	# if !GTEST_OS_WINDOWS_MOBILE
	#  include <direct.h>
	#  include <io.h>
	# endif
	// In order to avoid having to include <windows.h>, use forward declaration
	#if GTEST_OS_WINDOWS_MINGW && !defined(__MINGW64_VERSION_MAJOR)
	// MinGW defined _CRITICAL_SECTION and _RTL_CRITICAL_SECTION as two
	// separate (equivalent) structs, instead of using typedef
	typedef struct _CRITICAL_SECTION GTEST_CRITICAL_SECTION;
	#else
	// Assume CRITICAL_SECTION is a typedef of _RTL_CRITICAL_SECTION.
	// This assumption is verified by
	// WindowsTypesTest.CRITICAL_SECTIONIs_RTL_CRITICAL_SECTION.
	typedef struct _RTL_CRITICAL_SECTION GTEST_CRITICAL_SECTION;
	#endif
	#else
	// This assumes that non-Windows OSes provide unistd.h. For OSes where this
	// is not the case, we need to include headers that provide the functions
	// mentioned above.
	# include <unistd.h>
	# include <strings.h>
	#endif  // GTEST_OS_WINDOWS
	
	#if GTEST_OS_LINUX_ANDROID
	// Used to define __ANDROID_API__ matching the target NDK API level.
	#  include <android/api-level.h>  // NOLINT
	#endif
	
	// Defines this to true if Google Test can use POSIX regular expressions.
	#ifndef GTEST_HAS_POSIX_RE
	# if GTEST_OS_LINUX_ANDROID
	// On Android, <regex.h> is only available starting with Gingerbread.
	#  define GTEST_HAS_POSIX_RE (__ANDROID_API__ >= 9)
	# else
	#  define GTEST_HAS_POSIX_RE (!GTEST_OS_WINDOWS)
	# endif
	#endif
	
	#if GTEST_USES_PCRE
	// The appropriate headers have already been included.
	
	#elif GTEST_HAS_POSIX_RE
	
	// On some platforms, <regex.h> needs someone to define size_t, and
	// won't compile otherwise.  We can #include it here as we already
	// included <stdlib.h>, which is guaranteed to define size_t through
	// <stddef.h>.
	# include <regex.h>  // NOLINT
	
	# define GTEST_USES_POSIX_RE 1
	
	#elif GTEST_OS_WINDOWS
	
	// <regex.h> is not available on Windows.  Use our own simple regex
	// implementation instead.
	# define GTEST_USES_SIMPLE_RE 1
	
	#else
	
	// <regex.h> may not be available on this platform.  Use our own
	// simple regex implementation instead.
	# define GTEST_USES_SIMPLE_RE 1
	
	#endif  // GTEST_USES_PCRE
	
	#ifndef GTEST_HAS_EXCEPTIONS
	// The user didn't tell us whether exceptions are enabled, so we need
	// to figure it out.
	# if defined(_MSC_VER) && defined(_CPPUNWIND)
	// MSVC defines _CPPUNWIND to 1 if exceptions are enabled.
	#  define GTEST_HAS_EXCEPTIONS 1
	# elif defined(__BORLANDC__)
	// C++Builder's implementation of the STL uses the _HAS_EXCEPTIONS
	// macro to enable exceptions, so we'll do the same.
	// Assumes that exceptions are enabled by default.
	#  ifndef _HAS_EXCEPTIONS
	#   define _HAS_EXCEPTIONS 1
	#  endif  // _HAS_EXCEPTIONS
	#  define GTEST_HAS_EXCEPTIONS _HAS_EXCEPTIONS
	# elif defined(__clang__)
	// clang defines __EXCEPTIONS if exceptions are enabled before clang 220714,
	// but if cleanups are enabled after that. In Obj-C++ files, there can be
	// cleanups for ObjC exceptions which also need cleanups, even if C++ exceptions
	// are disabled. clang has __has_feature(cxx_exceptions) which checks for C++
	// exceptions starting at clang r206352, but which checked for cleanups prior to
	// that. To reliably check for C++ exception availability with clang, check for
	// __EXCEPTIONS && __has_feature(cxx_exceptions).
	#  define GTEST_HAS_EXCEPTIONS (__EXCEPTIONS && __has_feature(cxx_exceptions))
	# elif defined(__GNUC__) && __EXCEPTIONS
	// gcc defines __EXCEPTIONS to 1 if exceptions are enabled.
	#  define GTEST_HAS_EXCEPTIONS 1
	# elif defined(__SUNPRO_CC)
	// Sun Pro CC supports exceptions.  However, there is no compile-time way of
	// detecting whether they are enabled or not.  Therefore, we assume that
	// they are enabled unless the user tells us otherwise.
	#  define GTEST_HAS_EXCEPTIONS 1
	# elif defined(__IBMCPP__) && __EXCEPTIONS
	// xlC defines __EXCEPTIONS to 1 if exceptions are enabled.
	#  define GTEST_HAS_EXCEPTIONS 1
	# elif defined(__HP_aCC)
	// Exception handling is in effect by default in HP aCC compiler. It has to
	// be turned of by +noeh compiler option if desired.
	#  define GTEST_HAS_EXCEPTIONS 1
	# else
	// For other compilers, we assume exceptions are disabled to be
	// conservative.
	#  define GTEST_HAS_EXCEPTIONS 0
	# endif  // defined(_MSC_VER) || defined(__BORLANDC__)
	#endif  // GTEST_HAS_EXCEPTIONS
	
	#if !defined(GTEST_HAS_STD_STRING)
	// Even though we don't use this macro any longer, we keep it in case
	// some clients still depend on it.
	# define GTEST_HAS_STD_STRING 1
	#elif !GTEST_HAS_STD_STRING
	// The user told us that ::std::string isn't available.
	# error "::std::string isn't available."
	#endif  // !defined(GTEST_HAS_STD_STRING)
	
	#ifndef GTEST_HAS_STD_WSTRING
	// The user didn't tell us whether ::std::wstring is available, so we need
	// to figure it out.
	// Cygwin 1.7 and below doesn't support ::std::wstring.
	// Solaris' libc++ doesn't support it either.  Android has
	// no support for it at least as recent as Froyo (2.2).
	#define GTEST_HAS_STD_WSTRING                                         \
	  (!(GTEST_OS_LINUX_ANDROID || GTEST_OS_CYGWIN || GTEST_OS_SOLARIS || \
	     GTEST_OS_HAIKU))
	
	#endif  // GTEST_HAS_STD_WSTRING
	
	// Determines whether RTTI is available.
	#ifndef GTEST_HAS_RTTI
	// The user didn't tell us whether RTTI is enabled, so we need to
	// figure it out.
	
	# ifdef _MSC_VER
	
	#  ifdef _CPPRTTI  // MSVC defines this macro if RTTI is enabled.
	#   define GTEST_HAS_RTTI 1
	#  else
	#   define GTEST_HAS_RTTI 0
	#  endif
	
	// Starting with version 4.3.2, gcc defines __GXX_RTTI if RTTI is enabled.
	# elif defined(__GNUC__)
	
	#  ifdef __GXX_RTTI
	// When building against STLport with the Android NDK and with
	// -frtti -fno-exceptions, the build fails at link time with undefined
	// references to __cxa_bad_typeid. Note sure if STL or toolchain bug,
	// so disable RTTI when detected.
	#   if GTEST_OS_LINUX_ANDROID && defined(_STLPORT_MAJOR) && \
	       !defined(__EXCEPTIONS)
	#    define GTEST_HAS_RTTI 0
	#   else
	#    define GTEST_HAS_RTTI 1
	#   endif  // GTEST_OS_LINUX_ANDROID && __STLPORT_MAJOR && !__EXCEPTIONS
	#  else
	#   define GTEST_HAS_RTTI 0
	#  endif  // __GXX_RTTI
	
	// Clang defines __GXX_RTTI starting with version 3.0, but its manual recommends
	// using has_feature instead. has_feature(cxx_rtti) is supported since 2.7, the
	// first version with C++ support.
	# elif defined(__clang__)
	
	#  define GTEST_HAS_RTTI __has_feature(cxx_rtti)
	
	// Starting with version 9.0 IBM Visual Age defines __RTTI_ALL__ to 1 if
	// both the typeid and dynamic_cast features are present.
	# elif defined(__IBMCPP__) && (__IBMCPP__ >= 900)
	
	#  ifdef __RTTI_ALL__
	#   define GTEST_HAS_RTTI 1
	#  else
	#   define GTEST_HAS_RTTI 0
	#  endif
	
	# else
	
	// For all other compilers, we assume RTTI is enabled.
	#  define GTEST_HAS_RTTI 1
	
	# endif  // _MSC_VER
	
	#endif  // GTEST_HAS_RTTI
	
	// It's this header's responsibility to #include <typeinfo> when RTTI
	// is enabled.
	#if GTEST_HAS_RTTI
	# include <typeinfo>
	#endif
	
	// Determines whether Google Test can use the pthreads library.
	#ifndef GTEST_HAS_PTHREAD
	// The user didn't tell us explicitly, so we make reasonable assumptions about
	// which platforms have pthreads support.
	//
	// To disable threading support in Google Test, add -DGTEST_HAS_PTHREAD=0
	// to your compiler flags.
	#define GTEST_HAS_PTHREAD                                                      \
	  (GTEST_OS_LINUX || GTEST_OS_MAC || GTEST_OS_HPUX || GTEST_OS_QNX ||          \
	   GTEST_OS_FREEBSD || GTEST_OS_NACL || GTEST_OS_NETBSD || GTEST_OS_FUCHSIA || \
	   GTEST_OS_DRAGONFLY || GTEST_OS_GNU_KFREEBSD || GTEST_OS_OPENBSD ||          \
	   GTEST_OS_HAIKU)
	#endif  // GTEST_HAS_PTHREAD
	
	#if GTEST_HAS_PTHREAD
	// gtest-port.h guarantees to #include <pthread.h> when GTEST_HAS_PTHREAD is
	// true.
	# include <pthread.h>  // NOLINT
	
	// For timespec and nanosleep, used below.
	# include <time.h>  // NOLINT
	#endif
	
	// Determines whether clone(2) is supported.
	// Usually it will only be available on Linux, excluding
	// Linux on the Itanium architecture.
	// Also see http://linux.die.net/man/2/clone.
	#ifndef GTEST_HAS_CLONE
	// The user didn't tell us, so we need to figure it out.
	
	# if GTEST_OS_LINUX && !defined(__ia64__)
	#  if GTEST_OS_LINUX_ANDROID
	// On Android, clone() became available at different API levels for each 32-bit
	// architecture.
	#    if defined(__LP64__) || \
	        (defined(__arm__) && __ANDROID_API__ >= 9) || \
	        (defined(__mips__) && __ANDROID_API__ >= 12) || \
	        (defined(__i386__) && __ANDROID_API__ >= 17)
	#     define GTEST_HAS_CLONE 1
	#    else
	#     define GTEST_HAS_CLONE 0
	#    endif
	#  else
	#   define GTEST_HAS_CLONE 1
	#  endif
	# else
	#  define GTEST_HAS_CLONE 0
	# endif  // GTEST_OS_LINUX && !defined(__ia64__)
	
	#endif  // GTEST_HAS_CLONE
	
	// Determines whether to support stream redirection. This is used to test
	// output correctness and to implement death tests.
	#ifndef GTEST_HAS_STREAM_REDIRECTION
	// By default, we assume that stream redirection is supported on all
	// platforms except known mobile ones.
	# if GTEST_OS_WINDOWS_MOBILE || GTEST_OS_WINDOWS_PHONE || GTEST_OS_WINDOWS_RT
	#  define GTEST_HAS_STREAM_REDIRECTION 0
	# else
	#  define GTEST_HAS_STREAM_REDIRECTION 1
	# endif  // !GTEST_OS_WINDOWS_MOBILE
	#endif  // GTEST_HAS_STREAM_REDIRECTION
	
	// Determines whether to support death tests.
	// pops up a dialog window that cannot be suppressed programmatically.
	#if (GTEST_OS_LINUX || GTEST_OS_CYGWIN || GTEST_OS_SOLARIS ||             \
	     (GTEST_OS_MAC && !GTEST_OS_IOS) ||                                   \
	     (GTEST_OS_WINDOWS_DESKTOP && _MSC_VER) || GTEST_OS_WINDOWS_MINGW ||  \
	     GTEST_OS_AIX || GTEST_OS_HPUX || GTEST_OS_OPENBSD || GTEST_OS_QNX || \
	     GTEST_OS_FREEBSD || GTEST_OS_NETBSD || GTEST_OS_FUCHSIA ||           \
	     GTEST_OS_DRAGONFLY || GTEST_OS_GNU_KFREEBSD || GTEST_OS_HAIKU)
	# define GTEST_HAS_DEATH_TEST 1
	#endif
	
	// Determines whether to support type-driven tests.
	
	// Typed tests need <typeinfo> and variadic macros, which GCC, VC++ 8.0,
	// Sun Pro CC, IBM Visual Age, and HP aCC support.
	#if defined(__GNUC__) || defined(_MSC_VER) || defined(__SUNPRO_CC) || \
	    defined(__IBMCPP__) || defined(__HP_aCC)
	# define GTEST_HAS_TYPED_TEST 1
	# define GTEST_HAS_TYPED_TEST_P 1
	#endif
	
	// Determines whether the system compiler uses UTF-16 for encoding wide strings.
	#define GTEST_WIDE_STRING_USES_UTF16_ \
	  (GTEST_OS_WINDOWS || GTEST_OS_CYGWIN || GTEST_OS_AIX || GTEST_OS_OS2)
	
	// Determines whether test results can be streamed to a socket.
	#if GTEST_OS_LINUX || GTEST_OS_GNU_KFREEBSD || GTEST_OS_DRAGONFLY || \
	    GTEST_OS_FREEBSD || GTEST_OS_NETBSD || GTEST_OS_OPENBSD
	# define GTEST_CAN_STREAM_RESULTS_ 1
	#endif
	
	// Defines some utility macros.
	
	// The GNU compiler emits a warning if nested "if" statements are followed by
	// an "else" statement and braces are not used to explicitly disambiguate the
	// "else" binding.  This leads to problems with code like:
	//
	//   if (gate)
	//     ASSERT_*(condition) << "Some message";
	//
	// The "switch (0) case 0:" idiom is used to suppress this.
	#ifdef __INTEL_COMPILER
	# define GTEST_AMBIGUOUS_ELSE_BLOCKER_
	#else
	# define GTEST_AMBIGUOUS_ELSE_BLOCKER_ switch (0) case 0: default:  // NOLINT
	#endif
	
	// Use this annotation at the end of a struct/class definition to
	// prevent the compiler from optimizing away instances that are never
	// used.  This is useful when all interesting logic happens inside the
	// c'tor and / or d'tor.  Example:
	//
	//   struct Foo {
	//     Foo() { ... }
	//   } GTEST_ATTRIBUTE_UNUSED_;
	//
	// Also use it after a variable or parameter declaration to tell the
	// compiler the variable/parameter does not have to be used.
	#if defined(__GNUC__) && !defined(COMPILER_ICC)
	# define GTEST_ATTRIBUTE_UNUSED_ __attribute__ ((unused))
	#elif defined(__clang__)
	# if __has_attribute(unused)
	#  define GTEST_ATTRIBUTE_UNUSED_ __attribute__ ((unused))
	# endif
	#endif
	#ifndef GTEST_ATTRIBUTE_UNUSED_
	# define GTEST_ATTRIBUTE_UNUSED_
	#endif
	
	// Use this annotation before a function that takes a printf format string.
	#if (defined(__GNUC__) || defined(__clang__)) && !defined(COMPILER_ICC)
	# if defined(__MINGW_PRINTF_FORMAT)
	// MinGW has two different printf implementations. Ensure the format macro
	// matches the selected implementation. See
	// https://sourceforge.net/p/mingw-w64/wiki2/gnu%20printf/.
	#  define GTEST_ATTRIBUTE_PRINTF_(string_index, first_to_check) \
	       __attribute__((__format__(__MINGW_PRINTF_FORMAT, string_index, \
	                                 first_to_check)))
	# else
	#  define GTEST_ATTRIBUTE_PRINTF_(string_index, first_to_check) \
	       __attribute__((__format__(__printf__, string_index, first_to_check)))
	# endif
	#else
	# define GTEST_ATTRIBUTE_PRINTF_(string_index, first_to_check)
	#endif
	
	
	// A macro to disallow operator=
	// This should be used in the private: declarations for a class.
	#define GTEST_DISALLOW_ASSIGN_(type) \
	  void operator=(type const &) = delete
	
	// A macro to disallow copy constructor and operator=
	// This should be used in the private: declarations for a class.
	#define GTEST_DISALLOW_COPY_AND_ASSIGN_(type) \
	  type(type const &) = delete; \
	  GTEST_DISALLOW_ASSIGN_(type)
	
	// Tell the compiler to warn about unused return values for functions declared
	// with this macro.  The macro should be used on function declarations
	// following the argument list:
	//
	//   Sprocket* AllocateSprocket() GTEST_MUST_USE_RESULT_;
	#if defined(__GNUC__) && !defined(COMPILER_ICC)
	# define GTEST_MUST_USE_RESULT_ __attribute__ ((warn_unused_result))
	#else
	# define GTEST_MUST_USE_RESULT_
	#endif  // __GNUC__ && !COMPILER_ICC
	
	// MS C++ compiler emits warning when a conditional expression is compile time
	// constant. In some contexts this warning is false positive and needs to be
	// suppressed. Use the following two macros in such cases:
	//
	// GTEST_INTENTIONAL_CONST_COND_PUSH_()
	// while (true) {
	// GTEST_INTENTIONAL_CONST_COND_POP_()
	// }
	# define GTEST_INTENTIONAL_CONST_COND_PUSH_() \
	    GTEST_DISABLE_MSC_WARNINGS_PUSH_(4127)
	# define GTEST_INTENTIONAL_CONST_COND_POP_() \
	    GTEST_DISABLE_MSC_WARNINGS_POP_()
	
	// Determine whether the compiler supports Microsoft's Structured Exception
	// Handling.  This is supported by several Windows compilers but generally
	// does not exist on any other system.
	#ifndef GTEST_HAS_SEH
	// The user didn't tell us, so we need to figure it out.
	
	# if defined(_MSC_VER) || defined(__BORLANDC__)
	// These two compilers are known to support SEH.
	#  define GTEST_HAS_SEH 1
	# else
	// Assume no SEH.
	#  define GTEST_HAS_SEH 0
	# endif
	
	#endif  // GTEST_HAS_SEH
	
	#ifndef GTEST_IS_THREADSAFE
	
	#define GTEST_IS_THREADSAFE                                                 \
	  (GTEST_HAS_MUTEX_AND_THREAD_LOCAL_ ||                                     \
	   (GTEST_OS_WINDOWS && !GTEST_OS_WINDOWS_PHONE && !GTEST_OS_WINDOWS_RT) || \
	   GTEST_HAS_PTHREAD)
	
	#endif  // GTEST_IS_THREADSAFE
	
	// GTEST_API_ qualifies all symbols that must be exported. The definitions below
	// are guarded by #ifndef to give embedders a chance to define GTEST_API_ in
	// gtest/internal/custom/gtest-port.h
	#ifndef GTEST_API_
	
	#ifdef _MSC_VER
	# if GTEST_LINKED_AS_SHARED_LIBRARY
	#  define GTEST_API_ __declspec(dllimport)
	# elif GTEST_CREATE_SHARED_LIBRARY
	#  define GTEST_API_ __declspec(dllexport)
	# endif
	#elif __GNUC__ >= 4 || defined(__clang__)
	# define GTEST_API_ __attribute__((visibility ("default")))
	#endif  // _MSC_VER
	
	#endif  // GTEST_API_
	
	#ifndef GTEST_API_
	# define GTEST_API_
	#endif  // GTEST_API_
	
	#ifndef GTEST_DEFAULT_DEATH_TEST_STYLE
	# define GTEST_DEFAULT_DEATH_TEST_STYLE  "fast"
	#endif  // GTEST_DEFAULT_DEATH_TEST_STYLE
	
	#ifdef __GNUC__
	// Ask the compiler to never inline a given function.
	# define GTEST_NO_INLINE_ __attribute__((noinline))
	#else
	# define GTEST_NO_INLINE_
	#endif
	
	// _LIBCPP_VERSION is defined by the libc++ library from the LLVM project.
	#if !defined(GTEST_HAS_CXXABI_H_)
	# if defined(__GLIBCXX__) || (defined(_LIBCPP_VERSION) && !defined(_MSC_VER))
	#  define GTEST_HAS_CXXABI_H_ 1
	# else
	#  define GTEST_HAS_CXXABI_H_ 0
	# endif
	#endif
	
	// A function level attribute to disable checking for use of uninitialized
	// memory when built with MemorySanitizer.
	#if defined(__clang__)
	# if __has_feature(memory_sanitizer)
	#  define GTEST_ATTRIBUTE_NO_SANITIZE_MEMORY_ \
	       __attribute__((no_sanitize_memory))
	# else
	#  define GTEST_ATTRIBUTE_NO_SANITIZE_MEMORY_
	# endif  // __has_feature(memory_sanitizer)
	#else
	# define GTEST_ATTRIBUTE_NO_SANITIZE_MEMORY_
	#endif  // __clang__
	
	// A function level attribute to disable AddressSanitizer instrumentation.
	#if defined(__clang__)
	# if __has_feature(address_sanitizer)
	#  define GTEST_ATTRIBUTE_NO_SANITIZE_ADDRESS_ \
	       __attribute__((no_sanitize_address))
	# else
	#  define GTEST_ATTRIBUTE_NO_SANITIZE_ADDRESS_
	# endif  // __has_feature(address_sanitizer)
	#else
	# define GTEST_ATTRIBUTE_NO_SANITIZE_ADDRESS_
	#endif  // __clang__
	
	// A function level attribute to disable HWAddressSanitizer instrumentation.
	#if defined(__clang__)
	# if __has_feature(hwaddress_sanitizer)
	#  define GTEST_ATTRIBUTE_NO_SANITIZE_HWADDRESS_ \
	       __attribute__((no_sanitize("hwaddress")))
	# else
	#  define GTEST_ATTRIBUTE_NO_SANITIZE_HWADDRESS_
	# endif  // __has_feature(hwaddress_sanitizer)
	#else
	# define GTEST_ATTRIBUTE_NO_SANITIZE_HWADDRESS_
	#endif  // __clang__
	
	// A function level attribute to disable ThreadSanitizer instrumentation.
	#if defined(__clang__)
	# if __has_feature(thread_sanitizer)
	#  define GTEST_ATTRIBUTE_NO_SANITIZE_THREAD_ \
	       __attribute__((no_sanitize_thread))
	# else
	#  define GTEST_ATTRIBUTE_NO_SANITIZE_THREAD_
	# endif  // __has_feature(thread_sanitizer)
	#else
	# define GTEST_ATTRIBUTE_NO_SANITIZE_THREAD_
	#endif  // __clang__
	
	namespace testing {
	
	class Message;
	
	// Legacy imports for backwards compatibility.
	// New code should use std:: names directly.
	using std::get;
	using std::make_tuple;
	using std::tuple;
	using std::tuple_element;
	using std::tuple_size;
	
	namespace internal {
	
	// A secret type that Google Test users don't know about.  It has no
	// definition on purpose.  Therefore it's impossible to create a
	// Secret object, which is what we want.
	class Secret;
	
	// The GTEST_COMPILE_ASSERT_ is a legacy macro used to verify that a compile
	// time expression is true (in new code, use static_assert instead). For
	// example, you could use it to verify the size of a static array:
	//
	//   GTEST_COMPILE_ASSERT_(GTEST_ARRAY_SIZE_(names) == NUM_NAMES,
	//                         names_incorrect_size);
	//
	// The second argument to the macro must be a valid C++ identifier. If the
	// expression is false, compiler will issue an error containing this identifier.
	#define GTEST_COMPILE_ASSERT_(expr, msg) static_assert(expr, #msg)
	
	// StaticAssertTypeEqHelper is used by StaticAssertTypeEq defined in gtest.h.
	//
	// This template is declared, but intentionally undefined.
	template <typename T1, typename T2>
	struct StaticAssertTypeEqHelper;
	
	template <typename T>
	struct StaticAssertTypeEqHelper<T, T> {
	  enum { value = true };
	};
	
	// Same as std::is_same<>.
	template <typename T, typename U>
	struct IsSame {
	  enum { value = false };
	};
	template <typename T>
	struct IsSame<T, T> {
	  enum { value = true };
	};
	
	// Evaluates to the number of elements in 'array'.
	#define GTEST_ARRAY_SIZE_(array) (sizeof(array) / sizeof(array[0]))
	
	// A helper for suppressing warnings on constant condition.  It just
	// returns 'condition'.
	GTEST_API_ bool IsTrue(bool condition);
	
	// Defines RE.
	
	#if GTEST_USES_PCRE
	// if used, PCRE is injected by custom/gtest-port.h
	#elif GTEST_USES_POSIX_RE || GTEST_USES_SIMPLE_RE
	
	// A simple C++ wrapper for <regex.h>.  It uses the POSIX Extended
	// Regular Expression syntax.
	class GTEST_API_ RE {
	 public:
	  // A copy constructor is required by the Standard to initialize object
	  // references from r-values.
	  RE(const RE& other) { Init(other.pattern()); }
	
	  // Constructs an RE from a string.
	  RE(const ::std::string& regex) { Init(regex.c_str()); }  // NOLINT
	
	  RE(const char* regex) { Init(regex); }  // NOLINT
	  ~RE();
	
	  // Returns the string representation of the regex.
	  const char* pattern() const { return pattern_; }
	
	  // FullMatch(str, re) returns true if regular expression re matches
	  // the entire str.
	  // PartialMatch(str, re) returns true if regular expression re
	  // matches a substring of str (including str itself).
	  static bool FullMatch(const ::std::string& str, const RE& re) {
	    return FullMatch(str.c_str(), re);
	  }
	  static bool PartialMatch(const ::std::string& str, const RE& re) {
	    return PartialMatch(str.c_str(), re);
	  }
	
	  static bool FullMatch(const char* str, const RE& re);
	  static bool PartialMatch(const char* str, const RE& re);
	
	 private:
	  void Init(const char* regex);
	  const char* pattern_;
	  bool is_valid_;
	
	# if GTEST_USES_POSIX_RE
	
	  regex_t full_regex_;     // For FullMatch().
	  regex_t partial_regex_;  // For PartialMatch().
	
	# else  // GTEST_USES_SIMPLE_RE
	
	  const char* full_pattern_;  // For FullMatch();
	
	# endif
	
	  GTEST_DISALLOW_ASSIGN_(RE);
	};
	
	#endif  // GTEST_USES_PCRE
	
	// Formats a source file path and a line number as they would appear
	// in an error message from the compiler used to compile this code.
	GTEST_API_ ::std::string FormatFileLocation(const char* file, int line);
	
	// Formats a file location for compiler-independent XML output.
	// Although this function is not platform dependent, we put it next to
	// FormatFileLocation in order to contrast the two functions.
	GTEST_API_ ::std::string FormatCompilerIndependentFileLocation(const char* file,
	                                                               int line);
	
	// Defines logging utilities:
	//   GTEST_LOG_(severity) - logs messages at the specified severity level. The
	//                          message itself is streamed into the macro.
	//   LogToStderr()  - directs all log messages to stderr.
	//   FlushInfoLog() - flushes informational log messages.
	
	enum GTestLogSeverity {
	  GTEST_INFO,
	  GTEST_WARNING,
	  GTEST_ERROR,
	  GTEST_FATAL
	};
	
	// Formats log entry severity, provides a stream object for streaming the
	// log message, and terminates the message with a newline when going out of
	// scope.
	class GTEST_API_ GTestLog {
	 public:
	  GTestLog(GTestLogSeverity severity, const char* file, int line);
	
	  // Flushes the buffers and, if severity is GTEST_FATAL, aborts the program.
	  ~GTestLog();
	
	  ::std::ostream& GetStream() { return ::std::cerr; }
	
	 private:
	  const GTestLogSeverity severity_;
	
	  GTEST_DISALLOW_COPY_AND_ASSIGN_(GTestLog);
	};
	
	#if !defined(GTEST_LOG_)
	
	# define GTEST_LOG_(severity) \
	    ::testing::internal::GTestLog(::testing::internal::GTEST_##severity, \
	                                  __FILE__, __LINE__).GetStream()
	
	inline void LogToStderr() {}
	inline void FlushInfoLog() { fflush(nullptr); }
	
	#endif  // !defined(GTEST_LOG_)
	
	#if !defined(GTEST_CHECK_)
	// INTERNAL IMPLEMENTATION - DO NOT USE.
	//
	// GTEST_CHECK_ is an all-mode assert. It aborts the program if the condition
	// is not satisfied.
	//  Synopsys:
	//    GTEST_CHECK_(boolean_condition);
	//     or
	//    GTEST_CHECK_(boolean_condition) << "Additional message";
	//
	//    This checks the condition and if the condition is not satisfied
	//    it prints message about the condition violation, including the
	//    condition itself, plus additional message streamed into it, if any,
	//    and then it aborts the program. It aborts the program irrespective of
	//    whether it is built in the debug mode or not.
	# define GTEST_CHECK_(condition) \
	    GTEST_AMBIGUOUS_ELSE_BLOCKER_ \
	    if (::testing::internal::IsTrue(condition)) \
	      ; \
	    else \
	      GTEST_LOG_(FATAL) << "Condition " #condition " failed. "
	#endif  // !defined(GTEST_CHECK_)
	
	// An all-mode assert to verify that the given POSIX-style function
	// call returns 0 (indicating success).  Known limitation: this
	// doesn't expand to a balanced 'if' statement, so enclose the macro
	// in {} if you need to use it as the only statement in an 'if'
	// branch.
	#define GTEST_CHECK_POSIX_SUCCESS_(posix_call) \
	  if (const int gtest_error = (posix_call)) \
	    GTEST_LOG_(FATAL) << #posix_call << "failed with error " \
	                      << gtest_error
	
	// Adds reference to a type if it is not a reference type,
	// otherwise leaves it unchanged.  This is the same as
	// tr1::add_reference, which is not widely available yet.
	template <typename T>
	struct AddReference { typedef T& type; };  // NOLINT
	template <typename T>
	struct AddReference<T&> { typedef T& type; };  // NOLINT
	
	// A handy wrapper around AddReference that works when the argument T
	// depends on template parameters.
	#define GTEST_ADD_REFERENCE_(T) \
	    typename ::testing::internal::AddReference<T>::type
	
	// Transforms "T" into "const T&" according to standard reference collapsing
	// rules (this is only needed as a backport for C++98 compilers that do not
	// support reference collapsing). Specifically, it transforms:
	//
	//   char         ==> const char&
	//   const char   ==> const char&
	//   char&        ==> char&
	//   const char&  ==> const char&
	//
	// Note that the non-const reference will not have "const" added. This is
	// standard, and necessary so that "T" can always bind to "const T&".
	template <typename T>
	struct ConstRef { typedef const T& type; };
	template <typename T>
	struct ConstRef<T&> { typedef T& type; };
	
	// The argument T must depend on some template parameters.
	#define GTEST_REFERENCE_TO_CONST_(T) \
	  typename ::testing::internal::ConstRef<T>::type
	
	// INTERNAL IMPLEMENTATION - DO NOT USE IN USER CODE.
	//
	// Use ImplicitCast_ as a safe version of static_cast for upcasting in
	// the type hierarchy (e.g. casting a Foo* to a SuperclassOfFoo* or a
	// const Foo*).  When you use ImplicitCast_, the compiler checks that
	// the cast is safe.  Such explicit ImplicitCast_s are necessary in
	// surprisingly many situations where C++ demands an exact type match
	// instead of an argument type convertable to a target type.
	//
	// The syntax for using ImplicitCast_ is the same as for static_cast:
	//
	//   ImplicitCast_<ToType>(expr)
	//
	// ImplicitCast_ would have been part of the C++ standard library,
	// but the proposal was submitted too late.  It will probably make
	// its way into the language in the future.
	//
	// This relatively ugly name is intentional. It prevents clashes with
	// similar functions users may have (e.g., implicit_cast). The internal
	// namespace alone is not enough because the function can be found by ADL.
	template<typename To>
	inline To ImplicitCast_(To x) { return x; }
	
	// When you upcast (that is, cast a pointer from type Foo to type
	// SuperclassOfFoo), it's fine to use ImplicitCast_<>, since upcasts
	// always succeed.  When you downcast (that is, cast a pointer from
	// type Foo to type SubclassOfFoo), static_cast<> isn't safe, because
	// how do you know the pointer is really of type SubclassOfFoo?  It
	// could be a bare Foo, or of type DifferentSubclassOfFoo.  Thus,
	// when you downcast, you should use this macro.  In debug mode, we
	// use dynamic_cast<> to double-check the downcast is legal (we die
	// if it's not).  In normal mode, we do the efficient static_cast<>
	// instead.  Thus, it's important to test in debug mode to make sure
	// the cast is legal!
	//    This is the only place in the code we should use dynamic_cast<>.
	// In particular, you SHOULDN'T be using dynamic_cast<> in order to
	// do RTTI (eg code like this:
	//    if (dynamic_cast<Subclass1>(foo)) HandleASubclass1Object(foo);
	//    if (dynamic_cast<Subclass2>(foo)) HandleASubclass2Object(foo);
	// You should design the code some other way not to need this.
	//
	// This relatively ugly name is intentional. It prevents clashes with
	// similar functions users may have (e.g., down_cast). The internal
	// namespace alone is not enough because the function can be found by ADL.
	template<typename To, typename From>  // use like this: DownCast_<T*>(foo);
	inline To DownCast_(From* f) {  // so we only accept pointers
	  // Ensures that To is a sub-type of From *.  This test is here only
	  // for compile-time type checking, and has no overhead in an
	  // optimized build at run-time, as it will be optimized away
	  // completely.
	  GTEST_INTENTIONAL_CONST_COND_PUSH_()
	  if (false) {
	  GTEST_INTENTIONAL_CONST_COND_POP_()
	  const To to = nullptr;
	  ::testing::internal::ImplicitCast_<From*>(to);
	  }
	
	#if GTEST_HAS_RTTI
	  // RTTI: debug mode only!
	  GTEST_CHECK_(f == nullptr || dynamic_cast<To>(f) != nullptr);
	#endif
	  return static_cast<To>(f);
	}
	
	// Downcasts the pointer of type Base to Derived.
	// Derived must be a subclass of Base. The parameter MUST
	// point to a class of type Derived, not any subclass of it.
	// When RTTI is available, the function performs a runtime
	// check to enforce this.
	template <class Derived, class Base>
	Derived* CheckedDowncastToActualType(Base* base) {
	#if GTEST_HAS_RTTI
	  GTEST_CHECK_(typeid(*base) == typeid(Derived));
	#endif
	
	#if GTEST_HAS_DOWNCAST_
	  return ::down_cast<Derived*>(base);
	#elif GTEST_HAS_RTTI
	  return dynamic_cast<Derived*>(base);  // NOLINT
	#else
	  return static_cast<Derived*>(base);  // Poor man's downcast.
	#endif
	}
	
	#if GTEST_HAS_STREAM_REDIRECTION
	
	// Defines the stderr capturer:
	//   CaptureStdout     - starts capturing stdout.
	//   GetCapturedStdout - stops capturing stdout and returns the captured string.
	//   CaptureStderr     - starts capturing stderr.
	//   GetCapturedStderr - stops capturing stderr and returns the captured string.
	//
	GTEST_API_ void CaptureStdout();
	GTEST_API_ std::string GetCapturedStdout();
	GTEST_API_ void CaptureStderr();
	GTEST_API_ std::string GetCapturedStderr();
	
	#endif  // GTEST_HAS_STREAM_REDIRECTION
	// Returns the size (in bytes) of a file.
	GTEST_API_ size_t GetFileSize(FILE* file);
	
	// Reads the entire content of a file as a string.
	GTEST_API_ std::string ReadEntireFile(FILE* file);
	
	// All command line arguments.
	GTEST_API_ std::vector<std::string> GetArgvs();
	
	#if GTEST_HAS_DEATH_TEST
	
	std::vector<std::string> GetInjectableArgvs();
	// Deprecated: pass the args vector by value instead.
	void SetInjectableArgvs(const std::vector<std::string>* new_argvs);
	void SetInjectableArgvs(const std::vector<std::string>& new_argvs);
	void ClearInjectableArgvs();
	
	#endif  // GTEST_HAS_DEATH_TEST
	
	// Defines synchronization primitives.
	#if GTEST_IS_THREADSAFE
	# if GTEST_HAS_PTHREAD
	// Sleeps for (roughly) n milliseconds.  This function is only for testing
	// Google Test's own constructs.  Don't use it in user tests, either
	// directly or indirectly.
	inline void SleepMilliseconds(int n) {
	  const timespec time = {
	    0,                  // 0 seconds.
	    n * 1000L * 1000L,  // And n ms.
	  };
	  nanosleep(&time, nullptr);
	}
	# endif  // GTEST_HAS_PTHREAD
	
	# if GTEST_HAS_NOTIFICATION_
	// Notification has already been imported into the namespace.
	// Nothing to do here.
	
	# elif GTEST_HAS_PTHREAD
	// Allows a controller thread to pause execution of newly created
	// threads until notified.  Instances of this class must be created
	// and destroyed in the controller thread.
	//
	// This class is only for testing Google Test's own constructs. Do not
	// use it in user tests, either directly or indirectly.
	class Notification {
	 public:
	  Notification() : notified_(false) {
	    GTEST_CHECK_POSIX_SUCCESS_(pthread_mutex_init(&mutex_, nullptr));
	  }
	  ~Notification() {
	    pthread_mutex_destroy(&mutex_);
	  }
	
	  // Notifies all threads created with this notification to start. Must
	  // be called from the controller thread.
	  void Notify() {
	    pthread_mutex_lock(&mutex_);
	    notified_ = true;
	    pthread_mutex_unlock(&mutex_);
	  }
	
	  // Blocks until the controller thread notifies. Must be called from a test
	  // thread.
	  void WaitForNotification() {
	    for (;;) {
	      pthread_mutex_lock(&mutex_);
	      const bool notified = notified_;
	      pthread_mutex_unlock(&mutex_);
	      if (notified)
	        break;
	      SleepMilliseconds(10);
	    }
	  }
	
	 private:
	  pthread_mutex_t mutex_;
	  bool notified_;
	
	  GTEST_DISALLOW_COPY_AND_ASSIGN_(Notification);
	};
	
	# elif GTEST_OS_WINDOWS && !GTEST_OS_WINDOWS_PHONE && !GTEST_OS_WINDOWS_RT
	
	GTEST_API_ void SleepMilliseconds(int n);
	
	// Provides leak-safe Windows kernel handle ownership.
	// Used in death tests and in threading support.
	class GTEST_API_ AutoHandle {
	 public:
	  // Assume that Win32 HANDLE type is equivalent to void*. Doing so allows us to
	  // avoid including <windows.h> in this header file. Including <windows.h> is
	  // undesirable because it defines a lot of symbols and macros that tend to
	  // conflict with client code. This assumption is verified by
	  // WindowsTypesTest.HANDLEIsVoidStar.
	  typedef void* Handle;
	  AutoHandle();
	  explicit AutoHandle(Handle handle);
	
	  ~AutoHandle();
	
	  Handle Get() const;
	  void Reset();
	  void Reset(Handle handle);
	
	 private:
	  // Returns true if the handle is a valid handle object that can be closed.
	  bool IsCloseable() const;
	
	  Handle handle_;
	
	  GTEST_DISALLOW_COPY_AND_ASSIGN_(AutoHandle);
	};
	
	// Allows a controller thread to pause execution of newly created
	// threads until notified.  Instances of this class must be created
	// and destroyed in the controller thread.
	//
	// This class is only for testing Google Test's own constructs. Do not
	// use it in user tests, either directly or indirectly.
	class GTEST_API_ Notification {
	 public:
	  Notification();
	  void Notify();
	  void WaitForNotification();
	
	 private:
	  AutoHandle event_;
	
	  GTEST_DISALLOW_COPY_AND_ASSIGN_(Notification);
	};
	# endif  // GTEST_HAS_NOTIFICATION_
	
	// On MinGW, we can have both GTEST_OS_WINDOWS and GTEST_HAS_PTHREAD
	// defined, but we don't want to use MinGW's pthreads implementation, which
	// has conformance problems with some versions of the POSIX standard.
	# if GTEST_HAS_PTHREAD && !GTEST_OS_WINDOWS_MINGW
	
	// As a C-function, ThreadFuncWithCLinkage cannot be templated itself.
	// Consequently, it cannot select a correct instantiation of ThreadWithParam
	// in order to call its Run(). Introducing ThreadWithParamBase as a
	// non-templated base class for ThreadWithParam allows us to bypass this
	// problem.
	class ThreadWithParamBase {
	 public:
	  virtual ~ThreadWithParamBase() {}
	  virtual void Run() = 0;
	};
	
	// pthread_create() accepts a pointer to a function type with the C linkage.
	// According to the Standard (7.5/1), function types with different linkages
	// are different even if they are otherwise identical.  Some compilers (for
	// example, SunStudio) treat them as different types.  Since class methods
	// cannot be defined with C-linkage we need to define a free C-function to
	// pass into pthread_create().
	extern "C" inline void* ThreadFuncWithCLinkage(void* thread) {
	  static_cast<ThreadWithParamBase*>(thread)->Run();
	  return nullptr;
	}
	
	// Helper class for testing Google Test's multi-threading constructs.
	// To use it, write:
	//
	//   void ThreadFunc(int param) { /* Do things with param */ }
	//   Notification thread_can_start;
	//   ...
	//   // The thread_can_start parameter is optional; you can supply NULL.
	//   ThreadWithParam<int> thread(&ThreadFunc, 5, &thread_can_start);
	//   thread_can_start.Notify();
	//
	// These classes are only for testing Google Test's own constructs. Do
	// not use them in user tests, either directly or indirectly.
	template <typename T>
	class ThreadWithParam : public ThreadWithParamBase {
	 public:
	  typedef void UserThreadFunc(T);
	
	  ThreadWithParam(UserThreadFunc* func, T param, Notification* thread_can_start)
	      : func_(func),
	        param_(param),
	        thread_can_start_(thread_can_start),
	        finished_(false) {
	    ThreadWithParamBase* const base = this;
	    // The thread can be created only after all fields except thread_
	    // have been initialized.
	    GTEST_CHECK_POSIX_SUCCESS_(
	        pthread_create(&thread_, nullptr, &ThreadFuncWithCLinkage, base));
	  }
	  ~ThreadWithParam() override { Join(); }
	
	  void Join() {
	    if (!finished_) {
	      GTEST_CHECK_POSIX_SUCCESS_(pthread_join(thread_, nullptr));
	      finished_ = true;
	    }
	  }
	
	  void Run() override {
	    if (thread_can_start_ != nullptr) thread_can_start_->WaitForNotification();
	    func_(param_);
	  }
	
	 private:
	  UserThreadFunc* const func_;  // User-supplied thread function.
	  const T param_;  // User-supplied parameter to the thread function.
	  // When non-NULL, used to block execution until the controller thread
	  // notifies.
	  Notification* const thread_can_start_;
	  bool finished_;  // true if we know that the thread function has finished.
	  pthread_t thread_;  // The native thread object.
	
	  GTEST_DISALLOW_COPY_AND_ASSIGN_(ThreadWithParam);
	};
	# endif  // !GTEST_OS_WINDOWS && GTEST_HAS_PTHREAD ||
	         // GTEST_HAS_MUTEX_AND_THREAD_LOCAL_
	
	# if GTEST_HAS_MUTEX_AND_THREAD_LOCAL_
	// Mutex and ThreadLocal have already been imported into the namespace.
	// Nothing to do here.
	
	# elif GTEST_OS_WINDOWS && !GTEST_OS_WINDOWS_PHONE && !GTEST_OS_WINDOWS_RT
	
	// Mutex implements mutex on Windows platforms.  It is used in conjunction
	// with class MutexLock:
	//
	//   Mutex mutex;
	//   ...
	//   MutexLock lock(&mutex);  // Acquires the mutex and releases it at the
	//                            // end of the current scope.
	//
	// A static Mutex *must* be defined or declared using one of the following
	// macros:
	//   GTEST_DEFINE_STATIC_MUTEX_(g_some_mutex);
	//   GTEST_DECLARE_STATIC_MUTEX_(g_some_mutex);
	//
	// (A non-static Mutex is defined/declared in the usual way).
	class GTEST_API_ Mutex {
	 public:
	  enum MutexType { kStatic = 0, kDynamic = 1 };
	  // We rely on kStaticMutex being 0 as it is to what the linker initializes
	  // type_ in static mutexes.  critical_section_ will be initialized lazily
	  // in ThreadSafeLazyInit().
	  enum StaticConstructorSelector { kStaticMutex = 0 };
	
	  // This constructor intentionally does nothing.  It relies on type_ being
	  // statically initialized to 0 (effectively setting it to kStatic) and on
	  // ThreadSafeLazyInit() to lazily initialize the rest of the members.
	  explicit Mutex(StaticConstructorSelector /*dummy*/) {}
	
	  Mutex();
	  ~Mutex();
	
	  void Lock();
	
	  void Unlock();
	
	  // Does nothing if the current thread holds the mutex. Otherwise, crashes
	  // with high probability.
	  void AssertHeld();
	
	 private:
	  // Initializes owner_thread_id_ and critical_section_ in static mutexes.
	  void ThreadSafeLazyInit();
	
	  // Per https://blogs.msdn.microsoft.com/oldnewthing/20040223-00/?p=40503,
	  // we assume that 0 is an invalid value for thread IDs.
	  unsigned int owner_thread_id_;
	
	  // For static mutexes, we rely on these members being initialized to zeros
	  // by the linker.
	  MutexType type_;
	  long critical_section_init_phase_;  // NOLINT
	  GTEST_CRITICAL_SECTION* critical_section_;
	
	  GTEST_DISALLOW_COPY_AND_ASSIGN_(Mutex);
	};
	
	# define GTEST_DECLARE_STATIC_MUTEX_(mutex) \
	    extern ::testing::internal::Mutex mutex
	
	# define GTEST_DEFINE_STATIC_MUTEX_(mutex) \
	    ::testing::internal::Mutex mutex(::testing::internal::Mutex::kStaticMutex)
	
	// We cannot name this class MutexLock because the ctor declaration would
	// conflict with a macro named MutexLock, which is defined on some
	// platforms. That macro is used as a defensive measure to prevent against
	// inadvertent misuses of MutexLock like "MutexLock(&mu)" rather than
	// "MutexLock l(&mu)".  Hence the typedef trick below.
	class GTestMutexLock {
	 public:
	  explicit GTestMutexLock(Mutex* mutex)
	      : mutex_(mutex) { mutex_->Lock(); }
	
	  ~GTestMutexLock() { mutex_->Unlock(); }
	
	 private:
	  Mutex* const mutex_;
	
	  GTEST_DISALLOW_COPY_AND_ASSIGN_(GTestMutexLock);
	};
	
	typedef GTestMutexLock MutexLock;
	
	// Base class for ValueHolder<T>.  Allows a caller to hold and delete a value
	// without knowing its type.
	class ThreadLocalValueHolderBase {
	 public:
	  virtual ~ThreadLocalValueHolderBase() {}
	};
	
	// Provides a way for a thread to send notifications to a ThreadLocal
	// regardless of its parameter type.
	class ThreadLocalBase {
	 public:
	  // Creates a new ValueHolder<T> object holding a default value passed to
	  // this ThreadLocal<T>'s constructor and returns it.  It is the caller's
	  // responsibility not to call this when the ThreadLocal<T> instance already
	  // has a value on the current thread.
	  virtual ThreadLocalValueHolderBase* NewValueForCurrentThread() const = 0;
	
	 protected:
	  ThreadLocalBase() {}
	  virtual ~ThreadLocalBase() {}
	
	 private:
	  GTEST_DISALLOW_COPY_AND_ASSIGN_(ThreadLocalBase);
	};
	
	// Maps a thread to a set of ThreadLocals that have values instantiated on that
	// thread and notifies them when the thread exits.  A ThreadLocal instance is
	// expected to persist until all threads it has values on have terminated.
	class GTEST_API_ ThreadLocalRegistry {
	 public:
	  // Registers thread_local_instance as having value on the current thread.
	  // Returns a value that can be used to identify the thread from other threads.
	  static ThreadLocalValueHolderBase* GetValueOnCurrentThread(
	      const ThreadLocalBase* thread_local_instance);
	
	  // Invoked when a ThreadLocal instance is destroyed.
	  static void OnThreadLocalDestroyed(
	      const ThreadLocalBase* thread_local_instance);
	};
	
	class GTEST_API_ ThreadWithParamBase {
	 public:
	  void Join();
	
	 protected:
	  class Runnable {
	   public:
	    virtual ~Runnable() {}
	    virtual void Run() = 0;
	  };
	
	  ThreadWithParamBase(Runnable *runnable, Notification* thread_can_start);
	  virtual ~ThreadWithParamBase();
	
	 private:
	  AutoHandle thread_;
	};
	
	// Helper class for testing Google Test's multi-threading constructs.
	template <typename T>
	class ThreadWithParam : public ThreadWithParamBase {
	 public:
	  typedef void UserThreadFunc(T);
	
	  ThreadWithParam(UserThreadFunc* func, T param, Notification* thread_can_start)
	      : ThreadWithParamBase(new RunnableImpl(func, param), thread_can_start) {
	  }
	  virtual ~ThreadWithParam() {}
	
	 private:
	  class RunnableImpl : public Runnable {
	   public:
	    RunnableImpl(UserThreadFunc* func, T param)
	        : func_(func),
	          param_(param) {
	    }
	    virtual ~RunnableImpl() {}
	    virtual void Run() {
	      func_(param_);
	    }
	
	   private:
	    UserThreadFunc* const func_;
	    const T param_;
	
	    GTEST_DISALLOW_COPY_AND_ASSIGN_(RunnableImpl);
	  };
	
	  GTEST_DISALLOW_COPY_AND_ASSIGN_(ThreadWithParam);
	};
	
	// Implements thread-local storage on Windows systems.
	//
	//   // Thread 1
	//   ThreadLocal<int> tl(100);  // 100 is the default value for each thread.
	//
	//   // Thread 2
	//   tl.set(150);  // Changes the value for thread 2 only.
	//   EXPECT_EQ(150, tl.get());
	//
	//   // Thread 1
	//   EXPECT_EQ(100, tl.get());  // In thread 1, tl has the original value.
	//   tl.set(200);
	//   EXPECT_EQ(200, tl.get());
	//
	// The template type argument T must have a public copy constructor.
	// In addition, the default ThreadLocal constructor requires T to have
	// a public default constructor.
	//
	// The users of a TheadLocal instance have to make sure that all but one
	// threads (including the main one) using that instance have exited before
	// destroying it. Otherwise, the per-thread objects managed for them by the
	// ThreadLocal instance are not guaranteed to be destroyed on all platforms.
	//
	// Google Test only uses global ThreadLocal objects.  That means they
	// will die after main() has returned.  Therefore, no per-thread
	// object managed by Google Test will be leaked as long as all threads
	// using Google Test have exited when main() returns.
	template <typename T>
	class ThreadLocal : public ThreadLocalBase {
	 public:
	  ThreadLocal() : default_factory_(new DefaultValueHolderFactory()) {}
	  explicit ThreadLocal(const T& value)
	      : default_factory_(new InstanceValueHolderFactory(value)) {}
	
	  ~ThreadLocal() { ThreadLocalRegistry::OnThreadLocalDestroyed(this); }
	
	  T* pointer() { return GetOrCreateValue(); }
	  const T* pointer() const { return GetOrCreateValue(); }
	  const T& get() const { return *pointer(); }
	  void set(const T& value) { *pointer() = value; }
	
	 private:
	  // Holds a value of T.  Can be deleted via its base class without the caller
	  // knowing the type of T.
	  class ValueHolder : public ThreadLocalValueHolderBase {
	   public:
	    ValueHolder() : value_() {}
	    explicit ValueHolder(const T& value) : value_(value) {}
	
	    T* pointer() { return &value_; }
	
	   private:
	    T value_;
	    GTEST_DISALLOW_COPY_AND_ASSIGN_(ValueHolder);
	  };
	
	
	  T* GetOrCreateValue() const {
	    return static_cast<ValueHolder*>(
	        ThreadLocalRegistry::GetValueOnCurrentThread(this))->pointer();
	  }
	
	  virtual ThreadLocalValueHolderBase* NewValueForCurrentThread() const {
	    return default_factory_->MakeNewHolder();
	  }
	
	  class ValueHolderFactory {
	   public:
	    ValueHolderFactory() {}
	    virtual ~ValueHolderFactory() {}
	    virtual ValueHolder* MakeNewHolder() const = 0;
	
	   private:
	    GTEST_DISALLOW_COPY_AND_ASSIGN_(ValueHolderFactory);
	  };
	
	  class DefaultValueHolderFactory : public ValueHolderFactory {
	   public:
	    DefaultValueHolderFactory() {}
	    virtual ValueHolder* MakeNewHolder() const { return new ValueHolder(); }
	
	   private:
	    GTEST_DISALLOW_COPY_AND_ASSIGN_(DefaultValueHolderFactory);
	  };
	
	  class InstanceValueHolderFactory : public ValueHolderFactory {
	   public:
	    explicit InstanceValueHolderFactory(const T& value) : value_(value) {}
	    virtual ValueHolder* MakeNewHolder() const {
	      return new ValueHolder(value_);
	    }
	
	   private:
	    const T value_;  // The value for each thread.
	
	    GTEST_DISALLOW_COPY_AND_ASSIGN_(InstanceValueHolderFactory);
	  };
	
	  std::unique_ptr<ValueHolderFactory> default_factory_;
	
	  GTEST_DISALLOW_COPY_AND_ASSIGN_(ThreadLocal);
	};
	
	# elif GTEST_HAS_PTHREAD
	
	// MutexBase and Mutex implement mutex on pthreads-based platforms.
	class MutexBase {
	 public:
	  // Acquires this mutex.
	  void Lock() {

	    GTEST_CHECK_POSIX_SUCCESS_(pthread_mutex_lock(&mutex_));
	    owner_ = pthread_self();

	    has_owner_ = true;
	  }
	
	  // Releases this mutex.
	  void Unlock() {
	    // Since the lock is being released the owner_ field should no longer be
	    // considered valid. We don't protect writing to has_owner_ here, as it's
	    // the caller's responsibility to ensure that the current thread holds the
	    // mutex when this is called.

	    has_owner_ = false;
	    GTEST_CHECK_POSIX_SUCCESS_(pthread_mutex_unlock(&mutex_));
	  }
	
	  // Does nothing if the current thread holds the mutex. Otherwise, crashes
	  // with high probability.
	  void AssertHeld() const {
	    GTEST_CHECK_(has_owner_ && pthread_equal(owner_, pthread_self()))
	        << "The current thread is not holding the mutex @" << this;
	  }
	
	  // A static mutex may be used before main() is entered.  It may even
	  // be used before the dynamic initialization stage.  Therefore we
	  // must be able to initialize a static mutex object at link time.
	  // This means MutexBase has to be a POD and its member variables
	  // have to be public.
	 public:
	  pthread_mutex_t mutex_;  // The underlying pthread mutex.
	  // has_owner_ indicates whether the owner_ field below contains a valid thread
	  // ID and is therefore safe to inspect (e.g., to use in pthread_equal()). All
	  // accesses to the owner_ field should be protected by a check of this field.
	  // An alternative might be to memset() owner_ to all zeros, but there's no
	  // guarantee that a zero'd pthread_t is necessarily invalid or even different
	  // from pthread_self().
	  bool has_owner_;
	  pthread_t owner_;  // The thread holding the mutex.
	};
	
	// Forward-declares a static mutex.
	#  define GTEST_DECLARE_STATIC_MUTEX_(mutex) \
	     extern ::testing::internal::MutexBase mutex
	
	// Defines and statically (i.e. at link time) initializes a static mutex.
	// The initialization list here does not explicitly initialize each field,
	// instead relying on default initialization for the unspecified fields. In
	// particular, the owner_ field (a pthread_t) is not explicitly initialized.
	// This allows initialization to work whether pthread_t is a scalar or struct.
	// The flag -Wmissing-field-initializers must not be specified for this to work.
	#define GTEST_DEFINE_STATIC_MUTEX_(mutex) \
	  ::testing::internal::MutexBase mutex = {PTHREAD_MUTEX_INITIALIZER, false, 0}
	
	// The Mutex class can only be used for mutexes created at runtime. It
	// shares its API with MutexBase otherwise.
	class Mutex : public MutexBase {
	 public:
	  Mutex() {
	    GTEST_CHECK_POSIX_SUCCESS_(pthread_mutex_init(&mutex_, nullptr));
	    has_owner_ = false;
	  }
	  ~Mutex() {
	    GTEST_CHECK_POSIX_SUCCESS_(pthread_mutex_destroy(&mutex_));
	  }
	
	 private:
	  GTEST_DISALLOW_COPY_AND_ASSIGN_(Mutex);
	};
	
	// We cannot name this class MutexLock because the ctor declaration would
	// conflict with a macro named MutexLock, which is defined on some
	// platforms. That macro is used as a defensive measure to prevent against
	// inadvertent misuses of MutexLock like "MutexLock(&mu)" rather than
	// "MutexLock l(&mu)".  Hence the typedef trick below.
	class GTestMutexLock {
	 public:
	  explicit GTestMutexLock(MutexBase* mutex)
	      : mutex_(mutex) { mutex_->Lock(); }
	
	  ~GTestMutexLock() { mutex_->Unlock(); }
	
	 private:
	  MutexBase* const mutex_;
	
	  GTEST_DISALLOW_COPY_AND_ASSIGN_(GTestMutexLock);
	};
	
	typedef GTestMutexLock MutexLock;
	
	// Helpers for ThreadLocal.
	
	// pthread_key_create() requires DeleteThreadLocalValue() to have
	// C-linkage.  Therefore it cannot be templatized to access
	// ThreadLocal<T>.  Hence the need for class
	// ThreadLocalValueHolderBase.
	class ThreadLocalValueHolderBase {
	 public:
	  virtual ~ThreadLocalValueHolderBase() {}
	};
	
	// Called by pthread to delete thread-local data stored by
	// pthread_setspecific().
	extern "C" inline void DeleteThreadLocalValue(void* value_holder) {
	  delete static_cast<ThreadLocalValueHolderBase*>(value_holder);
	}
	
	// Implements thread-local storage on pthreads-based systems.
	template <typename T>
	class GTEST_API_ ThreadLocal {
	 public:
	  ThreadLocal()
	      : key_(CreateKey()), default_factory_(new DefaultValueHolderFactory()) {}
	  explicit ThreadLocal(const T& value)
	      : key_(CreateKey()),
	        default_factory_(new InstanceValueHolderFactory(value)) {}
	
	  ~ThreadLocal() {
	    // Destroys the managed object for the current thread, if any.
	    DeleteThreadLocalValue(pthread_getspecific(key_));
	
	    // Releases resources associated with the key.  This will *not*
	    // delete managed objects for other threads.
	    GTEST_CHECK_POSIX_SUCCESS_(pthread_key_delete(key_));
	  }
	
	  T* pointer() { return GetOrCreateValue(); }
	  const T* pointer() const { return GetOrCreateValue(); }
	  const T& get() const { return *pointer(); }
	  void set(const T& value) { *pointer() = value; }
	
	 private:
	  // Holds a value of type T.
	  class ValueHolder : public ThreadLocalValueHolderBase {
	   public:
	    ValueHolder() : value_() {}
	    explicit ValueHolder(const T& value) : value_(value) {}
	
	    T* pointer() { return &value_; }
	
	   private:
	    T value_;
	    GTEST_DISALLOW_COPY_AND_ASSIGN_(ValueHolder);
	  };
	
	  static pthread_key_t CreateKey() {
	    pthread_key_t key;
	    // When a thread exits, DeleteThreadLocalValue() will be called on
	    // the object managed for that thread.
	    GTEST_CHECK_POSIX_SUCCESS_(
	        pthread_key_create(&key, &DeleteThreadLocalValue));
	    return key;
	  }
	
	  T* GetOrCreateValue() const {
	    ThreadLocalValueHolderBase* const holder =
	        static_cast<ThreadLocalValueHolderBase*>(pthread_getspecific(key_));
	    if (holder != nullptr) {
	      return CheckedDowncastToActualType<ValueHolder>(holder)->pointer();
	    }
	
	    ValueHolder* const new_holder = default_factory_->MakeNewHolder();
	    ThreadLocalValueHolderBase* const holder_base = new_holder;
	    GTEST_CHECK_POSIX_SUCCESS_(pthread_setspecific(key_, holder_base));
	    return new_holder->pointer();
	  }
	
	  class ValueHolderFactory {
	   public:
	    ValueHolderFactory() {}
	    virtual ~ValueHolderFactory() {}
	    virtual ValueHolder* MakeNewHolder() const = 0;
	
	   private:
	    GTEST_DISALLOW_COPY_AND_ASSIGN_(ValueHolderFactory);
	  };
	
	  class DefaultValueHolderFactory : public ValueHolderFactory {
	   public:
	    DefaultValueHolderFactory() {}
	    virtual ValueHolder* MakeNewHolder() const { return new ValueHolder(); }
	
	   private:
	    GTEST_DISALLOW_COPY_AND_ASSIGN_(DefaultValueHolderFactory);
	  };
	
	  class InstanceValueHolderFactory : public ValueHolderFactory {
	   public:
	    explicit InstanceValueHolderFactory(const T& value) : value_(value) {}
	    virtual ValueHolder* MakeNewHolder() const {
	      return new ValueHolder(value_);
	    }
	
	   private:
	    const T value_;  // The value for each thread.
	
	    GTEST_DISALLOW_COPY_AND_ASSIGN_(InstanceValueHolderFactory);
	  };
	
	  // A key pthreads uses for looking up per-thread values.
	  const pthread_key_t key_;
	  std::unique_ptr<ValueHolderFactory> default_factory_;
	
	  GTEST_DISALLOW_COPY_AND_ASSIGN_(ThreadLocal);
	};
	
	# endif  // GTEST_HAS_MUTEX_AND_THREAD_LOCAL_
	
	#else  // GTEST_IS_THREADSAFE
	
	// A dummy implementation of synchronization primitives (mutex, lock,
	// and thread-local variable).  Necessary for compiling Google Test where
	// mutex is not supported - using Google Test in multiple threads is not
	// supported on such platforms.
	
	class Mutex {
	 public:
	  Mutex() {}
	  void Lock() {}
	  void Unlock() {}
	  void AssertHeld() const {}
	};
	
	# define GTEST_DECLARE_STATIC_MUTEX_(mutex) \
	  extern ::testing::internal::Mutex mutex
	
	# define GTEST_DEFINE_STATIC_MUTEX_(mutex) ::testing::internal::Mutex mutex
	
	// We cannot name this class MutexLock because the ctor declaration would
	// conflict with a macro named MutexLock, which is defined on some
	// platforms. That macro is used as a defensive measure to prevent against
	// inadvertent misuses of MutexLock like "MutexLock(&mu)" rather than
	// "MutexLock l(&mu)".  Hence the typedef trick below.
	class GTestMutexLock {
	 public:
	  explicit GTestMutexLock(Mutex*) {}  // NOLINT
	};
	
	typedef GTestMutexLock MutexLock;
	
	template <typename T>
	class GTEST_API_ ThreadLocal {
	 public:
	  ThreadLocal() : value_() {}
	  explicit ThreadLocal(const T& value) : value_(value) {}
	  T* pointer() { return &value_; }
	  const T* pointer() const { return &value_; }
	  const T& get() const { return value_; }
	  void set(const T& value) { value_ = value; }
	 private:
	  T value_;
	};
	
	#endif  // GTEST_IS_THREADSAFE
	
	// Returns the number of threads running in the process, or 0 to indicate that
	// we cannot detect it.
	GTEST_API_ size_t GetThreadCount();
	
	template <bool bool_value>
	struct bool_constant {
	  typedef bool_constant<bool_value> type;
	  static const bool value = bool_value;
	};
	template <bool bool_value> const bool bool_constant<bool_value>::value;
	
	typedef bool_constant<false> false_type;
	typedef bool_constant<true> true_type;
	
	template <typename T, typename U>
	struct is_same : public false_type {};
	
	template <typename T>
	struct is_same<T, T> : public true_type {};
	
	template <typename Iterator>
	struct IteratorTraits {
	  typedef typename Iterator::value_type value_type;
	};
	
	
	template <typename T>
	struct IteratorTraits<T*> {
	  typedef T value_type;
	};
	
	template <typename T>
	struct IteratorTraits<const T*> {
	  typedef T value_type;
	};
	
	#if GTEST_OS_WINDOWS
	# define GTEST_PATH_SEP_ "\\"
	# define GTEST_HAS_ALT_PATH_SEP_ 1
	// The biggest signed integer type the compiler supports.
	typedef __int64 BiggestInt;
	#else
	# define GTEST_PATH_SEP_ "/"
	# define GTEST_HAS_ALT_PATH_SEP_ 0
	typedef long long BiggestInt;  // NOLINT
	#endif  // GTEST_OS_WINDOWS
	
	// Utilities for char.
	
	// isspace(int ch) and friends accept an unsigned char or EOF.  char
	// may be signed, depending on the compiler (or compiler flags).
	// Therefore we need to cast a char to unsigned char before calling
	// isspace(), etc.
	
	inline bool IsAlpha(char ch) {
	  return isalpha(static_cast<unsigned char>(ch)) != 0;
	}
	inline bool IsAlNum(char ch) {
	  return isalnum(static_cast<unsigned char>(ch)) != 0;
	}
	inline bool IsDigit(char ch) {
	  return isdigit(static_cast<unsigned char>(ch)) != 0;
	}
	inline bool IsLower(char ch) {
	  return islower(static_cast<unsigned char>(ch)) != 0;
	}
	inline bool IsSpace(char ch) {
	  return isspace(static_cast<unsigned char>(ch)) != 0;
	}
	inline bool IsUpper(char ch) {
	  return isupper(static_cast<unsigned char>(ch)) != 0;
	}
	inline bool IsXDigit(char ch) {
	  return isxdigit(static_cast<unsigned char>(ch)) != 0;
	}
	inline bool IsXDigit(wchar_t ch) {
	  const unsigned char low_byte = static_cast<unsigned char>(ch);
	  return ch == low_byte && isxdigit(low_byte) != 0;
	}
	
	inline char ToLower(char ch) {
	  return static_cast<char>(tolower(static_cast<unsigned char>(ch)));
	}
	inline char ToUpper(char ch) {
	  return static_cast<char>(toupper(static_cast<unsigned char>(ch)));
	}
	
	inline std::string StripTrailingSpaces(std::string str) {
	  std::string::iterator it = str.end();
	  while (it != str.begin() && IsSpace(*--it))
	    it = str.erase(it);
	  return str;
	}
	
	// The testing::internal::posix namespace holds wrappers for common
	// POSIX functions.  These wrappers hide the differences between
	// Windows/MSVC and POSIX systems.  Since some compilers define these
	// standard functions as macros, the wrapper cannot have the same name
	// as the wrapped function.
	
	namespace posix {
	
	// Functions with a different name on Windows.
	
	#if GTEST_OS_WINDOWS
	
	typedef struct _stat StatStruct;
	
	# ifdef __BORLANDC__
	inline int IsATTY(int fd) { return isatty(fd); }
	inline int StrCaseCmp(const char* s1, const char* s2) {
	  return stricmp(s1, s2);
	}
	inline char* StrDup(const char* src) { return strdup(src); }
	# else  // !__BORLANDC__
	#  if GTEST_OS_WINDOWS_MOBILE
	inline int IsATTY(int /* fd */) { return 0; }
	#  else
	inline int IsATTY(int fd) { return _isatty(fd); }
	#  endif  // GTEST_OS_WINDOWS_MOBILE
	inline int StrCaseCmp(const char* s1, const char* s2) {
	  return _stricmp(s1, s2);
	}
	inline char* StrDup(const char* src) { return _strdup(src); }
	# endif  // __BORLANDC__
	
	# if GTEST_OS_WINDOWS_MOBILE
	inline int FileNo(FILE* file) { return reinterpret_cast<int>(_fileno(file)); }
	// Stat(), RmDir(), and IsDir() are not needed on Windows CE at this
	// time and thus not defined there.
	# else
	inline int FileNo(FILE* file) { return _fileno(file); }
	inline int Stat(const char* path, StatStruct* buf) { return _stat(path, buf); }
	inline int RmDir(const char* dir) { return _rmdir(dir); }
	inline bool IsDir(const StatStruct& st) {
	  return (_S_IFDIR & st.st_mode) != 0;
	}
	# endif  // GTEST_OS_WINDOWS_MOBILE
	
	#else
	
	typedef struct stat StatStruct;
	
	inline int FileNo(FILE* file) { return fileno(file); }
	inline int IsATTY(int fd) { return isatty(fd); }
	inline int Stat(const char* path, StatStruct* buf) { return stat(path, buf); }
	inline int StrCaseCmp(const char* s1, const char* s2) {
	  return strcasecmp(s1, s2);
	}
	inline char* StrDup(const char* src) { return strdup(src); }
	inline int RmDir(const char* dir) { return rmdir(dir); }
	inline bool IsDir(const StatStruct& st) { return S_ISDIR(st.st_mode); }
	
	#endif  // GTEST_OS_WINDOWS
	
	// Functions deprecated by MSVC 8.0.
	
	GTEST_DISABLE_MSC_DEPRECATED_PUSH_()
	
	inline const char* StrNCpy(char* dest, const char* src, size_t n) {
	  return strncpy(dest, src, n);
	}
	
	// ChDir(), FReopen(), FDOpen(), Read(), Write(), Close(), and
	// StrError() aren't needed on Windows CE at this time and thus not
	// defined there.
	
	#if !GTEST_OS_WINDOWS_MOBILE && !GTEST_OS_WINDOWS_PHONE && !GTEST_OS_WINDOWS_RT
	inline int ChDir(const char* dir) { return chdir(dir); }
	#endif
	inline FILE* FOpen(const char* path, const char* mode) {
	  return fopen(path, mode);
	}
	#if !GTEST_OS_WINDOWS_MOBILE
	inline FILE *FReopen(const char* path, const char* mode, FILE* stream) {
	  return freopen(path, mode, stream);
	}
	inline FILE* FDOpen(int fd, const char* mode) { return fdopen(fd, mode); }
	#endif
	inline int FClose(FILE* fp) { return fclose(fp); }
	#if !GTEST_OS_WINDOWS_MOBILE
	inline int Read(int fd, void* buf, unsigned int count) {
	  return static_cast<int>(read(fd, buf, count));
	}
	inline int Write(int fd, const void* buf, unsigned int count) {
	  return static_cast<int>(write(fd, buf, count));
	}
	inline int Close(int fd) { return close(fd); }
	inline const char* StrError(int errnum) { return strerror(errnum); }
	#endif
	inline const char* GetEnv(const char* name) {
	#if GTEST_OS_WINDOWS_MOBILE || GTEST_OS_WINDOWS_PHONE || GTEST_OS_WINDOWS_RT
	  // We are on Windows CE, which has no environment variables.
	  static_cast<void>(name);  // To prevent 'unused argument' warning.
	  return nullptr;
	#elif defined(__BORLANDC__) || defined(__SunOS_5_8) || defined(__SunOS_5_9)
	  // Environment variables which we programmatically clear will be set to the
	  // empty string rather than unset (NULL).  Handle that case.
	  const char* const env = getenv(name);
	  return (env != nullptr && env[0] != '\0') ? env : nullptr;
	#else
	  return getenv(name);
	#endif
	}
	
	GTEST_DISABLE_MSC_DEPRECATED_POP_()
	
	#if GTEST_OS_WINDOWS_MOBILE
	// Windows CE has no C library. The abort() function is used in
	// several places in Google Test. This implementation provides a reasonable
	// imitation of standard behaviour.
	[[noreturn]] void Abort();
	#else
	[[noreturn]] inline void Abort() { abort(); }
	#endif  // GTEST_OS_WINDOWS_MOBILE
	
	}  // namespace posix
	
	// MSVC "deprecates" snprintf and issues warnings wherever it is used.  In
	// order to avoid these warnings, we need to use _snprintf or _snprintf_s on
	// MSVC-based platforms.  We map the GTEST_SNPRINTF_ macro to the appropriate
	// function in order to achieve that.  We use macro definition here because
	// snprintf is a variadic function.
	#if _MSC_VER && !GTEST_OS_WINDOWS_MOBILE
	// MSVC 2005 and above support variadic macros.
	# define GTEST_SNPRINTF_(buffer, size, format, ...) \
	     _snprintf_s(buffer, size, size, format, __VA_ARGS__)
	#elif defined(_MSC_VER)
	// Windows CE does not define _snprintf_s
	# define GTEST_SNPRINTF_ _snprintf
	#else
	# define GTEST_SNPRINTF_ snprintf
	#endif
	
	// The maximum number a BiggestInt can represent.  This definition
	// works no matter BiggestInt is represented in one's complement or
	// two's complement.
	//
	// We cannot rely on numeric_limits in STL, as __int64 and long long
	// are not part of standard C++ and numeric_limits doesn't need to be
	// defined for them.
	const BiggestInt kMaxBiggestInt =
	    ~(static_cast<BiggestInt>(1) << (8*sizeof(BiggestInt) - 1));
	
	// This template class serves as a compile-time function from size to
	// type.  It maps a size in bytes to a primitive type with that
	// size. e.g.
	//
	//   TypeWithSize<4>::UInt
	//
	// is typedef-ed to be unsigned int (unsigned integer made up of 4
	// bytes).
	//
	// Such functionality should belong to STL, but I cannot find it
	// there.
	//
	// Google Test uses this class in the implementation of floating-point
	// comparison.
	//
	// For now it only handles UInt (unsigned int) as that's all Google Test
	// needs.  Other types can be easily added in the future if need
	// arises.
	template <size_t size>
	class TypeWithSize {
	 public:
	  // This prevents the user from using TypeWithSize<N> with incorrect
	  // values of N.
	  typedef void UInt;
	};
	
	// The specialization for size 4.
	template <>
	class TypeWithSize<4> {
	 public:
	  // unsigned int has size 4 in both gcc and MSVC.
	  //
	  // As base/basictypes.h doesn't compile on Windows, we cannot use
	  // uint32, uint64, and etc here.
	  typedef int Int;
	  typedef unsigned int UInt;
	};
	
	// The specialization for size 8.
	template <>
	class TypeWithSize<8> {
	 public:
	#if GTEST_OS_WINDOWS
	  typedef __int64 Int;
	  typedef unsigned __int64 UInt;
	#else
	  typedef long long Int;  // NOLINT
	  typedef unsigned long long UInt;  // NOLINT
	#endif  // GTEST_OS_WINDOWS
	};
	
	// Integer types of known sizes.
	typedef TypeWithSize<4>::Int Int32;
	typedef TypeWithSize<4>::UInt UInt32;
	typedef TypeWithSize<8>::Int Int64;
	typedef TypeWithSize<8>::UInt UInt64;
	typedef TypeWithSize<8>::Int TimeInMillis;  // Represents time in milliseconds.
	
	// Utilities for command line flags and environment variables.
	
	// Macro for referencing flags.
	#if !defined(GTEST_FLAG)
	# define GTEST_FLAG(name) FLAGS_gtest_##name
	#endif  // !defined(GTEST_FLAG)
	
	#if !defined(GTEST_USE_OWN_FLAGFILE_FLAG_)
	# define GTEST_USE_OWN_FLAGFILE_FLAG_ 1
	#endif  // !defined(GTEST_USE_OWN_FLAGFILE_FLAG_)
	
	#if !defined(GTEST_DECLARE_bool_)
	# define GTEST_FLAG_SAVER_ ::testing::internal::GTestFlagSaver
	
	// Macros for declaring flags.
	# define GTEST_DECLARE_bool_(name) GTEST_API_ extern bool GTEST_FLAG(name)
	# define GTEST_DECLARE_int32_(name) \
	    GTEST_API_ extern ::testing::internal::Int32 GTEST_FLAG(name)
	# define GTEST_DECLARE_string_(name) \
	    GTEST_API_ extern ::std::string GTEST_FLAG(name)
	
	// Macros for defining flags.
	# define GTEST_DEFINE_bool_(name, default_val, doc) \
	    GTEST_API_ bool GTEST_FLAG(name) = (default_val)
	# define GTEST_DEFINE_int32_(name, default_val, doc) \
	    GTEST_API_ ::testing::internal::Int32 GTEST_FLAG(name) = (default_val)
	# define GTEST_DEFINE_string_(name, default_val, doc) \
	    GTEST_API_ ::std::string GTEST_FLAG(name) = (default_val)
	
	#endif  // !defined(GTEST_DECLARE_bool_)
	
	// Thread annotations
	#if !defined(GTEST_EXCLUSIVE_LOCK_REQUIRED_)
	# define GTEST_EXCLUSIVE_LOCK_REQUIRED_(locks)
	# define GTEST_LOCK_EXCLUDED_(locks)
	#endif  // !defined(GTEST_EXCLUSIVE_LOCK_REQUIRED_)
	
	// Parses 'str' for a 32-bit signed integer.  If successful, writes the result
	// to *value and returns true; otherwise leaves *value unchanged and returns
	// false.
	bool ParseInt32(const Message& src_text, const char* str, Int32* value);
	
	// Parses a bool/Int32/string from the environment variable
	// corresponding to the given Google Test flag.
	bool BoolFromGTestEnv(const char* flag, bool default_val);
	GTEST_API_ Int32 Int32FromGTestEnv(const char* flag, Int32 default_val);
	std::string OutputFlagAlsoCheckEnvVar();
	const char* StringFromGTestEnv(const char* flag, const char* default_val);
	
	}  // namespace internal
	}  // namespace testing
	
	#if !defined(GTEST_INTERNAL_DEPRECATED)
	
	// Internal Macro to mark an API deprecated, for googletest usage only
	// Usage: class GTEST_INTERNAL_DEPRECATED(message) MyClass or
	// GTEST_INTERNAL_DEPRECATED(message) <return_type> myFunction(); Every usage of
	// a deprecated entity will trigger a warning when compiled with
	// `-Wdeprecated-declarations` option (clang, gcc, any __GNUC__ compiler).
	// For msvc /W3 option will need to be used
	// Note that for 'other' compilers this macro evaluates to nothing to prevent
	// compilations errors.
	#if defined(_MSC_VER)
	#define GTEST_INTERNAL_DEPRECATED(message) __declspec(deprecated(message))
	#elif defined(__GNUC__)
	#define GTEST_INTERNAL_DEPRECATED(message) __attribute__((deprecated(message)))
	#else
	#define GTEST_INTERNAL_DEPRECATED(message)
	#endif
	
	#endif  // !defined(GTEST_INTERNAL_DEPRECATED)
	
	#endif  // GTEST_INCLUDE_GTEST_INTERNAL_GTEST_PORT_H_