// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
******************************************************************************
*
*   Copyright (C) 1997-2016, International Business Machines
*   Corporation and others.  All Rights Reserved.
*
******************************************************************************
*
*  FILE NAME : platform.h
*
*   Date        Name        Description
*   05/13/98    nos         Creation (content moved here from ptypes.h).
*   03/02/99    stephen     Added AS400 support.
*   03/30/99    stephen     Added Linux support.
*   04/13/99    stephen     Reworked for autoconf.
******************************************************************************
*/

#ifndef _PLATFORM_H
#define _PLATFORM_H

#include "unicode/uconfig.h"
#include "unicode/uvernum.h"

/**
 * \file
 * \brief Basic types for the platform.
 *
 * This file used to be generated by autoconf/configure.
 * Starting with ICU 49, platform.h is a normal source file,
 * to simplify cross-compiling and working with non-autoconf/make build systems.
 *
 * When a value in this file does not work on a platform, then please
 * try to derive it from the U_PLATFORM value
 * (for which we might need a new value constant in rare cases)
 * and/or from other macros that are predefined by the compiler
 * or defined in standard (POSIX or platform or compiler) headers.
 *
 * As a temporary workaround, you can add an explicit \#define for some macros
 * before it is first tested, or add an equivalent -D macro definition
 * to the compiler's command line.
 *
 * Note: Some compilers provide ways to show the predefined macros.
 * For example, with gcc you can compile an empty .c file and have the compiler
 * print the predefined macros with
 * \code
 * gcc -E -dM -x c /dev/null | sort
 * \endcode
 * (You can provide an actual empty .c file rather than /dev/null.
 * <code>-x c++</code> is for C++.)
 */

/**
 * Define some things so that they can be documented.
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#ifdef U_IN_DOXYGEN
/*
 * Problem: "platform.h:335: warning: documentation for unknown define U_HAVE_STD_STRING found." means that U_HAVE_STD_STRING is not documented.
 * Solution: #define any defines for non \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only. API here, so that they are visible in the docs.  If you just set PREDEFINED in Doxyfile.in,  they won't be documented.
 */

/* None for now. */
#endif

/**
 * \def U_PLATFORM
 * The U_PLATFORM macro defines the platform we're on.
 *
 * We used to define one different, value-less macro per platform.
 * That made it hard to know the set of relevant platforms and macros,
 * and hard to deal with variants of platforms.
 *
 * Starting with ICU 49, we define platforms as numeric macros,
 * with ranges of values for related platforms and their variants.
 * The U_PLATFORM macro is set to one of these values.
 *
 * Historical note from the Solaris Wikipedia article:
 * AT&T and Sun collaborated on a project to merge the most popular Unix variants
 * on the market at that time: BSD, System V, and Xenix.
 * This became Unix System V Release 4 (SVR4).
 *
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */

/** Unknown platform. \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only. */
#define U_PF_UNKNOWN 0
/** Windows \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only. */
#define U_PF_WINDOWS 1000
/** MinGW. Windows, calls to Win32 API, but using GNU gcc and binutils. \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only. */
#define U_PF_MINGW 1800
/**
 * Cygwin. Windows, calls to cygwin1.dll for Posix functions,
 * using MSVC or GNU gcc and binutils.
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#define U_PF_CYGWIN 1900
/* Reserve 2000 for U_PF_UNIX? */
/** HP-UX is based on UNIX System V. \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only. */
#define U_PF_HPUX 2100
/** Solaris is a Unix operating system based on SVR4. \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only. */
#define U_PF_SOLARIS 2600
/** BSD is a UNIX operating system derivative. \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only. */
#define U_PF_BSD 3000
/** AIX is based on UNIX System V Releases and 4.3 BSD. \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only. */
#define U_PF_AIX 3100
/** IRIX is based on UNIX System V with BSD extensions. \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only. */
#define U_PF_IRIX 3200
/**
 * Darwin is a POSIX-compliant operating system, composed of code developed by Apple,
 * as well as code derived from NeXTSTEP, BSD, and other projects,
 * built around the Mach kernel.
 * Darwin forms the core set of components upon which Mac OS X, Apple TV, and iOS are based.
 * (Original description modified from WikiPedia.)
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#define U_PF_DARWIN 3500
/** iPhone OS (iOS) is a derivative of Mac OS X. \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only. */
#define U_PF_IPHONE 3550
/** QNX is a commercial Unix-like real-time operating system related to BSD. \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only. */
#define U_PF_QNX 3700
/** Linux is a Unix-like operating system. \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only. */
#define U_PF_LINUX 4000
/**
 * Native Client is pretty close to Linux.
 * See https://developer.chrome.com/native-client and
 *  http://www.chromium.org/nativeclient
 *  \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#define U_PF_BROWSER_NATIVE_CLIENT 4020
/** Android is based on Linux. \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only. */
#define U_PF_ANDROID 4050
/** Fuchsia is a POSIX-ish platform. \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only. */
#define U_PF_FUCHSIA 4100
/* Maximum value for Linux-based platform is 4499 */
/**
 * Emscripten is a C++ transpiler for the Web that can target asm.js or
 * WebAssembly. It provides some POSIX-compatible wrappers and stubs and
 * some Linux-like functionality, but is not fully compatible with
 * either.
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#define U_PF_EMSCRIPTEN 5010
/** z/OS is the successor to OS/390 which was the successor to MVS. \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only. */
#define U_PF_OS390 9000
/** "IBM i" is the current name of what used to be i5/OS and earlier OS/400. \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only. */
#define U_PF_OS400 9400

#ifdef U_PLATFORM
    /* Use the predefined value. */
#elif defined(__MINGW32__)
#   define U_PLATFORM U_PF_MINGW
#elif defined(__CYGWIN__)
#   define U_PLATFORM U_PF_CYGWIN
#elif defined(WIN32) || defined(_WIN32) || defined(WIN64) || defined(_WIN64)
#   define U_PLATFORM U_PF_WINDOWS
#elif defined(__ANDROID__)
#   define U_PLATFORM U_PF_ANDROID
    /* Android wchar_t support depends on the API level. */
#   include <android/api-level.h>
#elif defined(__pnacl__) || defined(__native_client__)
#   define U_PLATFORM U_PF_BROWSER_NATIVE_CLIENT
#elif defined(__Fuchsia__)
#   define U_PLATFORM U_PF_FUCHSIA
#elif defined(linux) || defined(__linux__) || defined(__linux)
#   define U_PLATFORM U_PF_LINUX
#elif defined(__APPLE__) && defined(__MACH__)
#   include <TargetConditionals.h>
#   if defined(TARGET_OS_IPHONE) && TARGET_OS_IPHONE  /* variant of TARGET_OS_MAC */
#       define U_PLATFORM U_PF_IPHONE
#   else
#       define U_PLATFORM U_PF_DARWIN
#   endif
#elif defined(BSD) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__MirBSD__)
#   if defined(__FreeBSD__)
#       include <sys/endian.h>
#   endif
#   define U_PLATFORM U_PF_BSD
#elif defined(sun) || defined(__sun)
    /* Check defined(__SVR4) || defined(__svr4__) to distinguish Solaris from SunOS? */
#   define U_PLATFORM U_PF_SOLARIS
#   if defined(__GNUC__)
        /* Solaris/GCC needs this header file to get the proper endianness. Normally, this
         * header file is included with stddef.h but on Solairs/GCC, the GCC version of stddef.h
         *  is included which does not include this header file.
         */
#       include <sys/isa_defs.h>
#   endif
#elif defined(_AIX) || defined(__TOS_AIX__)
#   define U_PLATFORM U_PF_AIX
#elif defined(_hpux) || defined(hpux) || defined(__hpux)
#   define U_PLATFORM U_PF_HPUX
#elif defined(sgi) || defined(__sgi)
#   define U_PLATFORM U_PF_IRIX
#elif defined(__QNX__) || defined(__QNXNTO__)
#   define U_PLATFORM U_PF_QNX
#elif defined(__TOS_MVS__)
#   define U_PLATFORM U_PF_OS390
#elif defined(__OS400__) || defined(__TOS_OS400__)
#   define U_PLATFORM U_PF_OS400
#elif defined(__EMSCRIPTEN__)
#   define U_PLATFORM U_PF_EMSCRIPTEN
#else
#   define U_PLATFORM U_PF_UNKNOWN
#endif

/**
 * \def CYGWINMSVC
 * Defined if this is Windows with Cygwin, but using MSVC rather than gcc.
 * Otherwise undefined.
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
/* Commented out because this is already set in mh-cygwin-msvc
#if U_PLATFORM == U_PF_CYGWIN && defined(_MSC_VER)
#   define CYGWINMSVC
#endif
*/
#ifdef U_IN_DOXYGEN
#   define CYGWINMSVC
#endif

/**
 * \def U_PLATFORM_USES_ONLY_WIN32_API
 * Defines whether the platform uses only the Win32 API.
 * Set to 1 for Windows/MSVC and MinGW but not Cygwin.
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#ifdef U_PLATFORM_USES_ONLY_WIN32_API
    /* Use the predefined value. */
#elif (U_PF_WINDOWS <= U_PLATFORM && U_PLATFORM <= U_PF_MINGW) || defined(CYGWINMSVC)
#   define U_PLATFORM_USES_ONLY_WIN32_API 1
#else
    /* Cygwin implements POSIX. */
#   define U_PLATFORM_USES_ONLY_WIN32_API 0
#endif

/**
 * \def U_PLATFORM_HAS_WIN32_API
 * Defines whether the Win32 API is available on the platform.
 * Set to 1 for Windows/MSVC, MinGW and Cygwin.
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#ifdef U_PLATFORM_HAS_WIN32_API
    /* Use the predefined value. */
#elif U_PF_WINDOWS <= U_PLATFORM && U_PLATFORM <= U_PF_CYGWIN
#   define U_PLATFORM_HAS_WIN32_API 1
#else
#   define U_PLATFORM_HAS_WIN32_API 0
#endif

/**
 * \def U_PLATFORM_HAS_WINUWP_API
 * Defines whether target is intended for Universal Windows Platform API
 * Set to 1 for Windows10 Release Solution Configuration
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#ifdef U_PLATFORM_HAS_WINUWP_API
    /* Use the predefined value. */
#else
#   define U_PLATFORM_HAS_WINUWP_API 0
#endif

/**
 * \def U_PLATFORM_IMPLEMENTS_POSIX
 * Defines whether the platform implements (most of) the POSIX API.
 * Set to 1 for Cygwin and most other platforms.
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#ifdef U_PLATFORM_IMPLEMENTS_POSIX
    /* Use the predefined value. */
#elif U_PLATFORM_USES_ONLY_WIN32_API
#   define U_PLATFORM_IMPLEMENTS_POSIX 0
#else
#   define U_PLATFORM_IMPLEMENTS_POSIX 1
#endif

/**
 * \def U_PLATFORM_IS_LINUX_BASED
 * Defines whether the platform is Linux or one of its derivatives.
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#ifdef U_PLATFORM_IS_LINUX_BASED
    /* Use the predefined value. */
#elif U_PF_LINUX <= U_PLATFORM && U_PLATFORM <= 4499
#   define U_PLATFORM_IS_LINUX_BASED 1
#else
#   define U_PLATFORM_IS_LINUX_BASED 0
#endif

/**
 * \def U_PLATFORM_IS_DARWIN_BASED
 * Defines whether the platform is Darwin or one of its derivatives.
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#ifdef U_PLATFORM_IS_DARWIN_BASED
    /* Use the predefined value. */
#elif U_PF_DARWIN <= U_PLATFORM && U_PLATFORM <= U_PF_IPHONE
#   define U_PLATFORM_IS_DARWIN_BASED 1
#else
#   define U_PLATFORM_IS_DARWIN_BASED 0
#endif

/**
 * \def U_HAVE_STDINT_H
 * Defines whether stdint.h is available. It is a C99 standard header.
 * We used to include inttypes.h which includes stdint.h but we usually do not need
 * the additional definitions from inttypes.h.
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#ifdef U_HAVE_STDINT_H
    /* Use the predefined value. */
#elif U_PLATFORM_USES_ONLY_WIN32_API
#   if defined(__BORLANDC__) || U_PLATFORM == U_PF_MINGW || (defined(_MSC_VER) && _MSC_VER>=1600)
        /* Windows Visual Studio 9 and below do not have stdint.h & inttypes.h, but VS 2010 adds them. */
#       define U_HAVE_STDINT_H 1
#   else
#       define U_HAVE_STDINT_H 0
#   endif
#elif U_PLATFORM == U_PF_SOLARIS
    /* Solaris has inttypes.h but not stdint.h. */
#   define U_HAVE_STDINT_H 0
#elif U_PLATFORM == U_PF_AIX && !defined(_AIX51) && defined(_POWER)
    /* PPC AIX <= 4.3 has inttypes.h but not stdint.h. */
#   define U_HAVE_STDINT_H 0
#else
#   define U_HAVE_STDINT_H 1
#endif

/**
 * \def U_HAVE_INTTYPES_H
 * Defines whether inttypes.h is available. It is a C99 standard header.
 * We include inttypes.h where it is available but stdint.h is not.
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#ifdef U_HAVE_INTTYPES_H
    /* Use the predefined value. */
#elif U_PLATFORM == U_PF_SOLARIS
    /* Solaris has inttypes.h but not stdint.h. */
#   define U_HAVE_INTTYPES_H 1
#elif U_PLATFORM == U_PF_AIX && !defined(_AIX51) && defined(_POWER)
    /* PPC AIX <= 4.3 has inttypes.h but not stdint.h. */
#   define U_HAVE_INTTYPES_H 1
#else
    /* Most platforms have both inttypes.h and stdint.h, or neither. */
#   define U_HAVE_INTTYPES_H U_HAVE_STDINT_H
#endif

/*===========================================================================*/
/** @{ Compiler and environment features                                     */
/*===========================================================================*/

/**
 * \def U_GCC_MAJOR_MINOR
 * Indicates whether the compiler is gcc (test for != 0),
 * and if so, contains its major (times 100) and minor version numbers.
 * If the compiler is not gcc, then U_GCC_MAJOR_MINOR == 0.
 *
 * For example, for testing for whether we have gcc, and whether it's 4.6 or higher,
 * use "#if U_GCC_MAJOR_MINOR >= 406".
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#ifdef __GNUC__
#   define U_GCC_MAJOR_MINOR (__GNUC__ * 100 + __GNUC_MINOR__)
#else
#   define U_GCC_MAJOR_MINOR 0
#endif

/**
 * \def U_IS_BIG_ENDIAN
 * Determines the endianness of the platform.
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#ifdef U_IS_BIG_ENDIAN
    /* Use the predefined value. */
#elif defined(BYTE_ORDER) && defined(BIG_ENDIAN)
#   define U_IS_BIG_ENDIAN (BYTE_ORDER == BIG_ENDIAN)
#elif defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__)
    /* gcc */
#   define U_IS_BIG_ENDIAN (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
#elif defined(__BIG_ENDIAN__) || defined(_BIG_ENDIAN)
#   define U_IS_BIG_ENDIAN 1
#elif defined(__LITTLE_ENDIAN__) || defined(_LITTLE_ENDIAN)
#   define U_IS_BIG_ENDIAN 0
#elif U_PLATFORM == U_PF_OS390 || U_PLATFORM == U_PF_OS400 || defined(__s390__) || defined(__s390x__)
    /* These platforms do not appear to predefine any endianness macros. */
#   define U_IS_BIG_ENDIAN 1
#elif defined(_PA_RISC1_0) || defined(_PA_RISC1_1) || defined(_PA_RISC2_0)
    /* HPPA do not appear to predefine any endianness macros. */
#   define U_IS_BIG_ENDIAN 1
#elif defined(sparc) || defined(__sparc) || defined(__sparc__)
    /* Some sparc based systems (e.g. Linux) do not predefine any endianness macros. */
#   define U_IS_BIG_ENDIAN 1
#else
#   define U_IS_BIG_ENDIAN 0
#endif

/**
 * \def U_HAVE_PLACEMENT_NEW
 * Determines whether to override placement new and delete for STL.
 * \xrefitem stable "Stable" "Stable List" ICU 2.6
 */
#ifdef U_HAVE_PLACEMENT_NEW
    /* Use the predefined value. */
#elif defined(__BORLANDC__)
#   define U_HAVE_PLACEMENT_NEW 0
#else
#   define U_HAVE_PLACEMENT_NEW 1
#endif

/**
 * \def U_HAVE_DEBUG_LOCATION_NEW 
 * Define this to define the MFC debug version of the operator new.
 *
 * \xrefitem stable "Stable" "Stable List" ICU 3.4
 */
#ifdef U_HAVE_DEBUG_LOCATION_NEW
    /* Use the predefined value. */
#elif defined(_MSC_VER)
#   define U_HAVE_DEBUG_LOCATION_NEW 1
#else
#   define U_HAVE_DEBUG_LOCATION_NEW 0
#endif

/* Compatibility with compilers other than clang: http://clang.llvm.org/docs/LanguageExtensions.html */
#ifdef __has_attribute
#   define UPRV_HAS_ATTRIBUTE(x) __has_attribute(x)
#else
#   define UPRV_HAS_ATTRIBUTE(x) 0
#endif
#ifdef __has_cpp_attribute
#   define UPRV_HAS_CPP_ATTRIBUTE(x) __has_cpp_attribute(x)
#else
#   define UPRV_HAS_CPP_ATTRIBUTE(x) 0
#endif
#ifdef __has_declspec_attribute
#   define UPRV_HAS_DECLSPEC_ATTRIBUTE(x) __has_declspec_attribute(x)
#else
#   define UPRV_HAS_DECLSPEC_ATTRIBUTE(x) 0
#endif
#ifdef __has_builtin
#   define UPRV_HAS_BUILTIN(x) __has_builtin(x)
#else
#   define UPRV_HAS_BUILTIN(x) 0
#endif
#ifdef __has_feature
#   define UPRV_HAS_FEATURE(x) __has_feature(x)
#else
#   define UPRV_HAS_FEATURE(x) 0
#endif
#ifdef __has_extension
#   define UPRV_HAS_EXTENSION(x) __has_extension(x)
#else
#   define UPRV_HAS_EXTENSION(x) 0
#endif
#ifdef __has_warning
#   define UPRV_HAS_WARNING(x) __has_warning(x)
#else
#   define UPRV_HAS_WARNING(x) 0
#endif

/**
 * \def U_MALLOC_ATTR
 * Attribute to mark functions as malloc-like
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#if defined(__GNUC__) && __GNUC__>=3
#    define U_MALLOC_ATTR __attribute__ ((__malloc__))
#else
#    define U_MALLOC_ATTR
#endif

/**
 * \def U_ALLOC_SIZE_ATTR
 * Attribute to specify the size of the allocated buffer for malloc-like functions
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#if (defined(__GNUC__) &&                                            \
        (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3))) || \
        UPRV_HAS_ATTRIBUTE(alloc_size)
#   define U_ALLOC_SIZE_ATTR(X) __attribute__ ((alloc_size(X)))
#   define U_ALLOC_SIZE_ATTR2(X,Y) __attribute__ ((alloc_size(X,Y)))
#else
#   define U_ALLOC_SIZE_ATTR(X)
#   define U_ALLOC_SIZE_ATTR2(X,Y)
#endif

/**
 * \def U_CPLUSPLUS_VERSION
 * 0 if no C++; 1, 11, 14, ... if C++.
 * Support for specific features cannot always be determined by the C++ version alone.
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#ifdef U_CPLUSPLUS_VERSION
#   if U_CPLUSPLUS_VERSION != 0 && !defined(__cplusplus)
#       undef U_CPLUSPLUS_VERSION
#       define U_CPLUSPLUS_VERSION 0
#   endif
    /* Otherwise use the predefined value. */
#elif !defined(__cplusplus)
#   define U_CPLUSPLUS_VERSION 0
#elif __cplusplus >= 201402L || (defined(_MSVC_LANG) && _MSVC_LANG >= 201402L)
#   define U_CPLUSPLUS_VERSION 14
#elif __cplusplus >= 201103L || (defined(_MSVC_LANG) && _MSVC_LANG >= 201103L)
#   define U_CPLUSPLUS_VERSION 11
#else
    // C++98 or C++03
#   define U_CPLUSPLUS_VERSION 1
#endif

#if (U_PLATFORM == U_PF_AIX || U_PLATFORM == U_PF_OS390) && defined(__cplusplus) &&(U_CPLUSPLUS_VERSION < 11)
// add in std::nullptr_t
namespace std {
  typedef decltype(nullptr) nullptr_t;
};
#endif

/**
 * \def U_NOEXCEPT
 * "noexcept" if supported, otherwise empty.
 * Some code, especially STL containers, uses move semantics of objects only
 * if the move constructor and the move operator are declared as not throwing exceptions.
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#ifdef U_NOEXCEPT
    /* Use the predefined value. */
#else
#   define U_NOEXCEPT noexcept
#endif

/**
 * \def U_FALLTHROUGH
 * Annotate intentional fall-through between switch labels.
 * http://clang.llvm.org/docs/AttributeReference.html#fallthrough-clang-fallthrough
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#ifndef __cplusplus
    // Not for C.
#elif defined(U_FALLTHROUGH)
    // Use the predefined value.
#elif defined(__clang__)
    // Test for compiler vs. feature separately.
    // Other compilers might choke on the feature test.
#    if UPRV_HAS_CPP_ATTRIBUTE(clang::fallthrough) || \
             (UPRV_HAS_FEATURE(cxx_attributes) &&     \
             UPRV_HAS_WARNING("-Wimplicit-fallthrough"))
#       define U_FALLTHROUGH [[clang::fallthrough]]
#   endif
#elif defined(__GNUC__) && (__GNUC__ >= 7)
#   define U_FALLTHROUGH __attribute__((fallthrough))
#endif

#ifndef U_FALLTHROUGH
#   define U_FALLTHROUGH
#endif

/** @} */

/*===========================================================================*/
/** @{ Character data types                                                  */
/*===========================================================================*/

/**
 * U_CHARSET_FAMILY is equal to this value when the platform is an ASCII based platform.
 * \xrefitem stable "Stable" "Stable List" ICU 2.0
 */
#define U_ASCII_FAMILY 0

/**
 * U_CHARSET_FAMILY is equal to this value when the platform is an EBCDIC based platform.
 * \xrefitem stable "Stable" "Stable List" ICU 2.0
 */
#define U_EBCDIC_FAMILY 1

/**
 * \def U_CHARSET_FAMILY
 *
 * <p>These definitions allow to specify the encoding of text
 * in the char data type as defined by the platform and the compiler.
 * It is enough to determine the code point values of "invariant characters",
 * which are the ones shared by all encodings that are in use
 * on a given platform.</p>
 *
 * <p>Those "invariant characters" should be all the uppercase and lowercase
 * latin letters, the digits, the space, and "basic punctuation".
 * Also, '\\n', '\\r', '\\t' should be available.</p>
 *
 * <p>The list of "invariant characters" is:<br>
 * \code
 *    A-Z  a-z  0-9  SPACE  "  %  &amp;  '  (  )  *  +  ,  -  .  /  :  ;  <  =  >  ?  _
 * \endcode
 * <br>
 * (52 letters + 10 numbers + 20 punc/sym/space = 82 total)</p>
 *
 * <p>This matches the IBM Syntactic Character Set (CS 640).</p>
 *
 * <p>In other words, all the graphic characters in 7-bit ASCII should
 * be safely accessible except the following:</p>
 *
 * \code
 *    '\' <backslash>
 *    '[' <left bracket>
 *    ']' <right bracket>
 *    '{' <left brace>
 *    '}' <right brace>
 *    '^' <circumflex>
 *    '~' <tilde>
 *    '!' <exclamation mark>
 *    '#' <number sign>
 *    '|' <vertical line>
 *    '$' <dollar sign>
 *    '@' <commercial at>
 *    '`' <grave accent>
 * \endcode
 * \xrefitem stable "Stable" "Stable List" ICU 2.0
 */
#ifdef U_CHARSET_FAMILY
    /* Use the predefined value. */
#elif U_PLATFORM == U_PF_OS390 && (!defined(__CHARSET_LIB) || !__CHARSET_LIB)
#   define U_CHARSET_FAMILY U_EBCDIC_FAMILY
#elif U_PLATFORM == U_PF_OS400 && !defined(__UTF32__)
#   define U_CHARSET_FAMILY U_EBCDIC_FAMILY
#else
#   define U_CHARSET_FAMILY U_ASCII_FAMILY
#endif

/**
 * \def U_CHARSET_IS_UTF8
 *
 * Hardcode the default charset to UTF-8.
 *
 * If this is set to 1, then
 * - ICU will assume that all non-invariant char*, StringPiece, std::string etc.
 *   contain UTF-8 text, regardless of what the system API uses
 * - some ICU code will use fast functions like u_strFromUTF8()
 *   rather than the more general and more heavy-weight conversion API (ucnv.h)
 * - ucnv_getDefaultName() always returns "UTF-8"
 * - ucnv_setDefaultName() is disabled and will not change the default charset
 * - static builds of ICU are smaller
 * - more functionality is available with the UCONFIG_NO_CONVERSION build-time
 *   configuration option (see unicode/uconfig.h)
 * - the UCONFIG_NO_CONVERSION build option in uconfig.h is more usable
 *
 * \xrefitem stable "Stable" "Stable List" ICU 4.2
 * @see UCONFIG_NO_CONVERSION
 */
#ifdef U_CHARSET_IS_UTF8
    /* Use the predefined value. */
#elif U_PLATFORM_IS_LINUX_BASED || U_PLATFORM_IS_DARWIN_BASED || \
        U_PLATFORM == U_PF_EMSCRIPTEN
#   define U_CHARSET_IS_UTF8 1
#else
#   define U_CHARSET_IS_UTF8 0
#endif

/** @} */

/*===========================================================================*/
/** @{ Information about wchar support                                       */
/*===========================================================================*/

/**
 * \def U_HAVE_WCHAR_H
 * Indicates whether <wchar.h> is available (1) or not (0). Set to 1 by default.
 *
 * \xrefitem stable "Stable" "Stable List" ICU 2.0
 */
#ifdef U_HAVE_WCHAR_H
    /* Use the predefined value. */
#elif U_PLATFORM == U_PF_ANDROID && __ANDROID_API__ < 9
    /*
     * Android before Gingerbread (Android 2.3, API level 9) did not support wchar_t.
     * The type and header existed, but the library functions did not work as expected.
     * The size of wchar_t was 1 but L"xyz" string literals had 32-bit units anyway.
     */
#   define U_HAVE_WCHAR_H 0
#else
#   define U_HAVE_WCHAR_H 1
#endif

/**
 * \def U_SIZEOF_WCHAR_T
 * U_SIZEOF_WCHAR_T==sizeof(wchar_t)
 *
 * \xrefitem stable "Stable" "Stable List" ICU 2.0
 */
#ifdef U_SIZEOF_WCHAR_T
    /* Use the predefined value. */
#elif (U_PLATFORM == U_PF_ANDROID && __ANDROID_API__ < 9)
    /*
     * Classic Mac OS and Mac OS X before 10.3 (Panther) did not support wchar_t or wstring.
     * Newer Mac OS X has size 4.
     */
#   define U_SIZEOF_WCHAR_T 1
#elif U_PLATFORM_HAS_WIN32_API || U_PLATFORM == U_PF_CYGWIN
#   define U_SIZEOF_WCHAR_T 2
#elif U_PLATFORM == U_PF_AIX
    /*
     * AIX 6.1 information, section "Wide character data representation":
     * "... the wchar_t datatype is 32-bit in the 64-bit environment and
     * 16-bit in the 32-bit environment."
     * and
     * "All locales use Unicode for their wide character code values (process code),
     * except the IBM-eucTW codeset."
     */
#   ifdef __64BIT__
#       define U_SIZEOF_WCHAR_T 4
#   else
#       define U_SIZEOF_WCHAR_T 2
#   endif
#elif U_PLATFORM == U_PF_OS390
    /*
     * z/OS V1R11 information center, section "LP64 | ILP32":
     * "In 31-bit mode, the size of long and pointers is 4 bytes and the size of wchar_t is 2 bytes.
     * Under LP64, the size of long and pointer is 8 bytes and the size of wchar_t is 4 bytes."
     */
#   ifdef _LP64
#       define U_SIZEOF_WCHAR_T 4
#   else
#       define U_SIZEOF_WCHAR_T 2
#   endif
#elif U_PLATFORM == U_PF_OS400
#   if defined(__UTF32__)
        /*
         * LOCALETYPE(*LOCALEUTF) is specified.
         * Wide-character strings are in UTF-32,
         * narrow-character strings are in UTF-8.
         */
#       define U_SIZEOF_WCHAR_T 4
#   elif defined(__UCS2__)
        /*
         * LOCALETYPE(*LOCALEUCS2) is specified.
         * Wide-character strings are in UCS-2,
         * narrow-character strings are in EBCDIC.
         */
#       define U_SIZEOF_WCHAR_T 2
#   else
        /*
         * LOCALETYPE(*CLD) or LOCALETYPE(*LOCALE) is specified.
         * Wide-character strings are in 16-bit EBCDIC,
         * narrow-character strings are in EBCDIC.
         */
#       define U_SIZEOF_WCHAR_T 2
#   endif
#else
#   define U_SIZEOF_WCHAR_T 4
#endif

#ifndef U_HAVE_WCSCPY
#define U_HAVE_WCSCPY U_HAVE_WCHAR_H
#endif

/** @} */

/**
 * \def U_HAVE_CHAR16_T
 * Defines whether the char16_t type is available for UTF-16
 * and u"abc" UTF-16 string literals are supported.
 * This is a new standard type and standard string literal syntax in C++0x
 * but has been available in some compilers before.
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#ifdef U_HAVE_CHAR16_T
    /* Use the predefined value. */
#else
    /*
     * Notes:
     * Visual Studio 2010 (_MSC_VER==1600) defines char16_t as a typedef
     * and does not support u"abc" string literals.
     * Visual Studio 2015 (_MSC_VER>=1900) and above adds support for
     * both char16_t and u"abc" string literals.
     * gcc 4.4 defines the __CHAR16_TYPE__ macro to a usable type but
     * does not support u"abc" string literals.
     * C++11 and C11 require support for UTF-16 literals
     * TODO: Fix for plain C. Doesn't work on Mac.
     */
#   if U_CPLUSPLUS_VERSION >= 11 || (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L)
#       define U_HAVE_CHAR16_T 1
#   else
#       define U_HAVE_CHAR16_T 0
#   endif
#endif

/**
 * @{
 * \def U_DECLARE_UTF16
 * Do not use this macro because it is not defined on all platforms.
 * Use the UNICODE_STRING or U_STRING_DECL macros instead.
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#ifdef U_DECLARE_UTF16
    /* Use the predefined value. */
#elif U_HAVE_CHAR16_T \
    || (defined(__xlC__) && defined(__IBM_UTF_LITERAL) && U_SIZEOF_WCHAR_T != 2) \
    || (defined(__HP_aCC) && __HP_aCC >= 035000) \
    || (defined(__HP_cc) && __HP_cc >= 111106) \
    || (defined(U_IN_DOXYGEN))
#   define U_DECLARE_UTF16(string) u ## string
#elif U_SIZEOF_WCHAR_T == 2 \
    && (U_CHARSET_FAMILY == 0 || (U_PF_OS390 <= U_PLATFORM && U_PLATFORM <= U_PF_OS400 && defined(__UCS2__)))
#   define U_DECLARE_UTF16(string) L ## string
#else
    /* Leave U_DECLARE_UTF16 undefined. See unistr.h. */
#endif

/** @} */

/*===========================================================================*/
/** @{ Symbol import-export control                                          */
/*===========================================================================*/

#ifdef U_EXPORT
    /* Use the predefined value. */
#elif defined(U_STATIC_IMPLEMENTATION)
#   define U_EXPORT
#elif defined(_MSC_VER) || (UPRV_HAS_DECLSPEC_ATTRIBUTE(dllexport) && \
                            UPRV_HAS_DECLSPEC_ATTRIBUTE(dllimport))
#   define U_EXPORT __declspec(dllexport)
#elif defined(__GNUC__)
#   define U_EXPORT __attribute__((visibility("default")))
#elif (defined(__SUNPRO_CC) && __SUNPRO_CC >= 0x550) \
   || (defined(__SUNPRO_C) && __SUNPRO_C >= 0x550) 
#   define U_EXPORT __global
/*#elif defined(__HP_aCC) || defined(__HP_cc)
#   define U_EXPORT __declspec(dllexport)*/
#else
#   define U_EXPORT
#endif

/* U_CALLCONV is related to U_EXPORT2 */
#ifdef U_EXPORT2
    /* Use the predefined value. */
#elif defined(_MSC_VER)
#   define U_EXPORT2 __cdecl
#else
#   define U_EXPORT2
#endif

#ifdef U_IMPORT
    /* Use the predefined value. */
#elif defined(_MSC_VER) || (UPRV_HAS_DECLSPEC_ATTRIBUTE(dllexport) && \
                            UPRV_HAS_DECLSPEC_ATTRIBUTE(dllimport))
    /* Windows needs to export/import data. */
#   define U_IMPORT __declspec(dllimport)
#else
#   define U_IMPORT 
#endif

/**
 * \def U_CALLCONV
 * Similar to U_CDECL_BEGIN/U_CDECL_END, this qualifier is necessary
 * in callback function typedefs to make sure that the calling convention
 * is compatible.
 *
 * This is only used for non-ICU-API functions.
 * When a function is a public ICU API,
 * you must use the U_CAPI and U_EXPORT2 qualifiers.
 *
 * Please note, you need to use U_CALLCONV after the *.
 *
 * NO : "static const char U_CALLCONV *func( . . . )"
 * YES: "static const char* U_CALLCONV func( . . . )"
 *
 * \xrefitem stable "Stable" "Stable List" ICU 2.0
 */
#if U_PLATFORM == U_PF_OS390 && defined(__cplusplus)
#    define U_CALLCONV __cdecl
#else
#    define U_CALLCONV U_EXPORT2
#endif

/**
 * \def U_CALLCONV_FPTR
 * Similar to U_CALLCONV, but only used on function pointers.
 * \xrefitem internal "Internal"  "Internal List"  Do not use. This API is for internal use only.
 */
#if U_PLATFORM == U_PF_OS390 && defined(__cplusplus)
#    define U_CALLCONV_FPTR U_CALLCONV
#else
#    define U_CALLCONV_FPTR
#endif
/** @} */

#endif  // _PLATFORM_H