【QT】Qt Compiler Detection（编译）

╰半夏微凉° 2022-06-10 02:51 674阅读 0赞

## 1、Compiler&GNU ##

Qt是跨平台的，从下面的编译配置选项（宏）中可以看出Qt支持的编译环境。

// qcompilerdetection.h
    /*
       The compiler, must be one of: (Q_CC_x)
    
         SYM      - Digital Mars C/C++ (used to be Symantec C++)
         MSVC     - Microsoft Visual C/C++, Intel C++ for Windows
         BOR      - Borland/Turbo C++
         WAT      - Watcom C++
         GNU      - GNU C++
         COMEAU   - Comeau C++
         EDG      - Edison Design Group C++
         OC       - CenterLine C++
         SUN      - Forte Developer, or Sun Studio C++
         MIPS     - MIPSpro C++
         DEC      - DEC C++
         HPACC    - HP aC++
         USLC     - SCO OUDK and UDK
         CDS      - Reliant C++
         KAI      - KAI C++
         INTEL    - Intel C++ for Linux, Intel C++ for Windows
         HIGHC    - MetaWare High C/C++
         PGI      - Portland Group C++
         GHS      - Green Hills Optimizing C++ Compilers
         RVCT     - ARM Realview Compiler Suite
         CLANG    - C++ front-end for the LLVM compiler
    
       Should be sorted most to least authoritative.
    */

或者如下所示的Qt支持的OS。

// qsystemdetection.h    
    /*
       The operating system, must be one of: (Q_OS_x)
    
         DARWIN   - Any Darwin system (macOS, iOS, watchOS, tvOS)
         MACOS    - macOS
         IOS      - iOS
         WATCHOS  - watchOS
         TVOS     - tvOS
         MSDOS    - MS-DOS and Windows
         OS2      - OS/2
         OS2EMX   - XFree86 on OS/2 (not PM)
         WIN32    - Win32 (Windows 2000/XP/Vista/7 and Windows Server 2003/2008)
         WINRT    - WinRT (Windows 8 Runtime)
         CYGWIN   - Cygwin
         SOLARIS  - Sun Solaris
         HPUX     - HP-UX
         ULTRIX   - DEC Ultrix
         LINUX    - Linux [has variants]
         FREEBSD  - FreeBSD [has variants]
         NETBSD   - NetBSD
         OPENBSD  - OpenBSD
         BSDI     - BSD/OS
         INTERIX  - Interix
         IRIX     - SGI Irix
         OSF      - HP Tru64 UNIX
         SCO      - SCO OpenServer 5
         UNIXWARE - UnixWare 7, Open UNIX 8
         AIX      - AIX
         HURD     - GNU Hurd
         DGUX     - DG/UX
         RELIANT  - Reliant UNIX
         DYNIX    - DYNIX/ptx
         QNX      - QNX [has variants]
         QNX6     - QNX RTP 6.1
         LYNX     - LynxOS
         BSD4     - Any BSD 4.4 system
         UNIX     - Any UNIX BSD/SYSV system
         ANDROID  - Android platform
         HAIKU    - Haiku
    
       The following operating systems have variants:
         LINUX    - both Q_OS_LINUX and Q_OS_ANDROID are defined when building for Android
                  - only Q_OS_LINUX is defined if building for other Linux systems
         FREEBSD  - Q_OS_FREEBSD is defined only when building for FreeBSD with a BSD userland
                  - Q_OS_FREEBSD_KERNEL is always defined on FreeBSD, even if the userland is from GNU
    */

以GNU为例，我们来看看Qt通过gcc的特性定义了那些东西，如常见的`__attribute__`。

// qcompilerdetection.h
    // ... other compilers
    #elif defined(__GNUC__)
    # define Q_CC_GNU (__GNUC__ * 100 + __GNUC_MINOR__) // gnu
    # if defined(__MINGW32__)
    # define Q_CC_MINGW // mingw
    # endif
    # if defined(__INTEL_COMPILER)
    # define Q_CC_INTEL (__INTEL_COMPILER) // intel
    // ... intel compiler
    # else
    /* Plain GCC */
    # if Q_CC_GNU >= 405 // version
    # define Q_ASSUME_IMPL(expr) if (expr){} else __builtin_unreachable()
    # define Q_UNREACHABLE_IMPL() __builtin_unreachable()
    # define Q_DECL_DEPRECATED_X(text) __attribute__ ((__deprecated__(text)))
    # endif
    # endif
    
    # ifdef Q_OS_WIN // win
    # define Q_DECL_EXPORT __declspec(dllexport)
    # define Q_DECL_IMPORT __declspec(dllimport)
    # elif defined(QT_VISIBILITY_AVAILABLE) // linux
    # define Q_DECL_EXPORT __attribute__((visibility("default")))
    # define Q_DECL_IMPORT __attribute__((visibility("default")))
    # define Q_DECL_HIDDEN __attribute__((visibility("hidden")))
    # endif
    
    # define Q_FUNC_INFO __PRETTY_FUNCTION__
    # define Q_ALIGNOF(type) __alignof__(type)
    # define Q_TYPEOF(expr) __typeof__(expr)
    # define Q_DECL_DEPRECATED __attribute__ ((__deprecated__))
    # define Q_DECL_ALIGN(n) __attribute__((__aligned__(n)))
    # define Q_DECL_UNUSED __attribute__((__unused__))
    # define Q_LIKELY(expr) __builtin_expect(!!(expr), true)
    # define Q_UNLIKELY(expr) __builtin_expect(!!(expr), false)
    # define Q_NORETURN __attribute__((__noreturn__))
    # define Q_REQUIRED_RESULT __attribute__ ((__warn_unused_result__))
    # define Q_DECL_PURE_FUNCTION __attribute__((pure))
    # define Q_DECL_CONST_FUNCTION __attribute__((const))
    # if !defined(QT_MOC_CPP) // no moc
    # define Q_PACKED __attribute__ ((__packed__))
    # ifndef __ARM_EABI__ // no arm eabi
    # define QT_NO_ARM_EABI
    # endif
    # endif
    # if Q_CC_GNU >= 403 && !defined(Q_CC_CLANG) // version && non-clang
    # define Q_ALLOC_SIZE(x) __attribute__((alloc_size(x)))
    # endif

## 2、C++11&GNU ##

下面是gcc各版本对C++11的支持所涉及的宏。

// qcompilerdetection.h
    #if defined(Q_CC_GNU) && !defined(Q_CC_INTEL) && !defined(Q_CC_CLANG)
    # define Q_COMPILER_RESTRICTED_VLA
    # define Q_COMPILER_THREADSAFE_STATICS
    # if Q_CC_GNU >= 403
    // GCC supports binary literals in C, C++98 and C++11 modes
    # define Q_COMPILER_BINARY_LITERALS
    # endif
    # if !defined(__STRICT_ANSI__) || defined(__GXX_EXPERIMENTAL_CXX0X__) \
        || (defined(__cplusplus) && (__cplusplus >= 201103L)) \
        || (defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L))
         // Variadic macros are supported for gnu++98, c++11, C99 ... since forever (gcc 2.97)
    # define Q_COMPILER_VARIADIC_MACROS
    # endif
    # if defined(__GXX_EXPERIMENTAL_CXX0X__) || __cplusplus >= 201103L
    # if Q_CC_GNU >= 403
           /* C++11 features supported in GCC 4.3: */
    # define Q_COMPILER_DECLTYPE
    # define Q_COMPILER_RVALUE_REFS
    # define Q_COMPILER_STATIC_ASSERT
    # endif
    # if Q_CC_GNU >= 404
           /* C++11 features supported in GCC 4.4: */
    # define Q_COMPILER_AUTO_FUNCTION
    # define Q_COMPILER_AUTO_TYPE
    # define Q_COMPILER_EXTERN_TEMPLATES
    # define Q_COMPILER_UNIFORM_INIT
    # define Q_COMPILER_UNICODE_STRINGS
    # define Q_COMPILER_VARIADIC_TEMPLATES
    # endif
    # if Q_CC_GNU >= 405
           /* C++11 features supported in GCC 4.5: */
    # define Q_COMPILER_EXPLICIT_CONVERSIONS
           /* GCC 4.4 implements initializer_list but does not define typedefs required * by the standard. */
    # define Q_COMPILER_INITIALIZER_LISTS
    # define Q_COMPILER_LAMBDA
    # define Q_COMPILER_RAW_STRINGS
    # define Q_COMPILER_CLASS_ENUM
    # endif
    # if Q_CC_GNU >= 406
           /* Pre-4.6 compilers implement a non-final snapshot of N2346, hence default and delete * functions are supported only if they are public. Starting from 4.6, GCC handles * final version - the access modifier is not relevant. */
    # define Q_COMPILER_DEFAULT_MEMBERS
    # define Q_COMPILER_DELETE_MEMBERS
           /* C++11 features supported in GCC 4.6: */
    # define Q_COMPILER_CONSTEXPR
    # define Q_COMPILER_NULLPTR
    # define Q_COMPILER_UNRESTRICTED_UNIONS
    # define Q_COMPILER_RANGE_FOR
    # endif
    # if Q_CC_GNU >= 407
           /* GCC 4.4 implemented <atomic> and std::atomic using its old intrinsics. * However, the implementation is incomplete for most platforms until GCC 4.7: * instead, std::atomic would use an external lock. Since we need an std::atomic * that is behavior-compatible with QBasicAtomic, we only enable it here */
    # define Q_COMPILER_ATOMICS
           /* GCC 4.6.x has problems dealing with noexcept expressions, * so turn the feature on for 4.7 and above, only */
    # define Q_COMPILER_NOEXCEPT
           /* C++11 features supported in GCC 4.7: */
    # define Q_COMPILER_NONSTATIC_MEMBER_INIT
    # define Q_COMPILER_DELEGATING_CONSTRUCTORS
    # define Q_COMPILER_EXPLICIT_OVERRIDES
    # define Q_COMPILER_TEMPLATE_ALIAS
    # define Q_COMPILER_UDL
    # endif
    # if Q_CC_GNU >= 408
    # define Q_COMPILER_ATTRIBUTES
    # define Q_COMPILER_ALIGNAS
    # define Q_COMPILER_ALIGNOF
    # define Q_COMPILER_INHERITING_CONSTRUCTORS
    # define Q_COMPILER_THREAD_LOCAL
    # if Q_CC_GNU > 408 || __GNUC_PATCHLEVEL__ >= 1
    # define Q_COMPILER_REF_QUALIFIERS
    # endif
    # endif
         /* C++11 features are complete as of GCC 4.8.1 */
    # endif
    # if __cplusplus > 201103L
    # if Q_CC_GNU >= 409
         /* C++1y features in GCC 4.9 - deprecated, do not update this list */
    //# define Q_COMPILER_BINARY_LITERALS // already supported since GCC 4.3 as an extension
    # define Q_COMPILER_LAMBDA_CAPTURES
    # define Q_COMPILER_RETURN_TYPE_DEDUCTION
    # endif
    # endif
    #endif

## 3、C++11 keywords ##

下面是与C++11各关键字相关的宏，如常见的`= default`、`= delete`。

// qcompilerdetection.h
    /* * C++11 keywords and expressions */
    #ifdef Q_COMPILER_NULLPTR
    # define Q_NULLPTR nullptr
    #else
    # define Q_NULLPTR NULL
    #endif
    
    #ifdef Q_COMPILER_DEFAULT_MEMBERS
    # define Q_DECL_EQ_DEFAULT = default
    #else
    # define Q_DECL_EQ_DEFAULT
    #endif
    
    #ifdef Q_COMPILER_DELETE_MEMBERS
    # define Q_DECL_EQ_DELETE = delete
    #else
    # define Q_DECL_EQ_DELETE
    #endif
    
    // Don't break code that is already using Q_COMPILER_DEFAULT_DELETE_MEMBERS
    #if defined(Q_COMPILER_DEFAULT_MEMBERS) && defined(Q_COMPILER_DELETE_MEMBERS)
    # define Q_COMPILER_DEFAULT_DELETE_MEMBERS
    #endif
    
    #if defined Q_COMPILER_CONSTEXPR
    # if defined(__cpp_constexpr) && __cpp_constexpr-0 >= 201304
    # define Q_DECL_CONSTEXPR constexpr
    # define Q_DECL_RELAXED_CONSTEXPR constexpr
    # define Q_CONSTEXPR constexpr
    # define Q_RELAXED_CONSTEXPR constexpr
    # else
    # define Q_DECL_CONSTEXPR constexpr
    # define Q_DECL_RELAXED_CONSTEXPR
    # define Q_CONSTEXPR constexpr
    # define Q_RELAXED_CONSTEXPR const
    # endif
    #else
    # define Q_DECL_CONSTEXPR
    # define Q_DECL_RELAXED_CONSTEXPR
    # define Q_CONSTEXPR const
    # define Q_RELAXED_CONSTEXPR const
    #endif
    
    #ifdef Q_COMPILER_EXPLICIT_OVERRIDES
    # define Q_DECL_OVERRIDE override
    # define Q_DECL_FINAL final
    #else
    # ifndef Q_DECL_OVERRIDE
    # define Q_DECL_OVERRIDE
    # endif
    # ifndef Q_DECL_FINAL
    # define Q_DECL_FINAL
    # endif
    #endif
    
    #ifdef Q_COMPILER_NOEXCEPT
    # define Q_DECL_NOEXCEPT noexcept
    # define Q_DECL_NOEXCEPT_EXPR(x) noexcept(x)
    # ifdef Q_DECL_NOTHROW
    # undef Q_DECL_NOTHROW /* override with C++11 noexcept if available */
    # endif
    #else
    # define Q_DECL_NOEXCEPT
    # define Q_DECL_NOEXCEPT_EXPR(x)
    #endif
    #ifndef Q_DECL_NOTHROW
    # define Q_DECL_NOTHROW Q_DECL_NOEXCEPT
    #endif
    
    #if defined(Q_COMPILER_ALIGNOF)
    # undef Q_ALIGNOF
    # define Q_ALIGNOF(x) alignof(x)
    #endif
    
    #if defined(Q_COMPILER_ALIGNAS)
    # undef Q_DECL_ALIGN
    # define Q_DECL_ALIGN(n) alignas(n)
    #endif

## 4、C++ standard ##

C++标准参考：[https://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations][https_isocpp.org_std_standing-documents_sd-6-sg10-feature-test-recommendations]  
下面是sg10-sd6给出的一些C++特性。

// qcompilerdetection.h
    #ifdef __has_builtin
    # define QT_HAS_BUILTIN(x) __has_builtin(x)
    #else
    # define QT_HAS_BUILTIN(x) 0
    #endif
    #ifdef __has_attribute
    # define QT_HAS_ATTRIBUTE(x) __has_attribute(x)
    #else
    # define QT_HAS_ATTRIBUTE(x) 0
    #endif
    #ifdef __has_cpp_attribute
    # define QT_HAS_CPP_ATTRIBUTE(x) __has_cpp_attribute(x)
    #else
    # define QT_HAS_CPP_ATTRIBUTE(x) 0
    #endif
    #ifdef __has_include
    # define QT_HAS_INCLUDE(x) __has_include(x)
    #else
    # define QT_HAS_INCLUDE(x) 0
    #endif
    #ifdef __has_include_next
    # define QT_HAS_INCLUDE_NEXT(x) __has_include_next(x)
    #else
    # define QT_HAS_INCLUDE_NEXT(x) 0
    #endif

## 5、Warning handling ##

在编译代码时，常会看到一些Warning，这些Warning可以通过技术手段规避，如下的一些宏定义，将会产生警告的代码置于`push`与`pop`之间，或者直接`disable`或`ignored`会产生警告的编译规则。

// qcompilerdetection.h
    #define QT_DO_PRAGMA(text) _Pragma(#text)
    // ... other compilers
    #elif defined(Q_CC_MSVC) && _MSC_VER >= 1500 && !defined(Q_CC_CLANG)
    # undef QT_DO_PRAGMA /* not needed */
    # define QT_WARNING_PUSH __pragma(warning(push))
    # define QT_WARNING_POP __pragma(warning(pop))
    # define QT_WARNING_DISABLE_MSVC(number) __pragma(warning(disable: number))
    # define QT_WARNING_DISABLE_INTEL(number)
    # define QT_WARNING_DISABLE_CLANG(text)
    # define QT_WARNING_DISABLE_GCC(text)
    # define QT_WARNING_DISABLE_DEPRECATED QT_WARNING_DISABLE_MSVC(4996)
    #elif defined(Q_CC_GNU) && (__GNUC__ * 100 + __GNUC_MINOR__ >= 406)
    # define QT_WARNING_PUSH QT_DO_PRAGMA(GCC diagnostic push)
    # define QT_WARNING_POP QT_DO_PRAGMA(GCC diagnostic pop)
    # define QT_WARNING_DISABLE_GCC(text) QT_DO_PRAGMA(GCC diagnostic ignored text)
    # define QT_WARNING_DISABLE_CLANG(text)
    # define QT_WARNING_DISABLE_INTEL(number)
    # define QT_WARNING_DISABLE_MSVC(number)
    # define QT_WARNING_DISABLE_DEPRECATED QT_WARNING_DISABLE_GCC("-Wdeprecated-declarations")
    #else // All other compilers, GCC < 4.6 and MSVC < 2008
    # define QT_WARNING_DISABLE_GCC(text)
    # define QT_WARNING_PUSH
    # define QT_WARNING_POP
    # define QT_WARNING_DISABLE_INTEL(number)
    # define QT_WARNING_DISABLE_MSVC(number)
    # define QT_WARNING_DISABLE_CLANG(text)
    # define QT_WARNING_DISABLE_GCC(text)
    # define QT_WARNING_DISABLE_DEPRECATED
    #endif

## 6、arch processor ##

下面是Qt支持的处理器类型（ARCH\_PROCESSOR），如常见的`i386`、`x86_64`等。

// archdetect.cpp
    // main part: processor type
    #if defined(Q_PROCESSOR_ALPHA)
    # define ARCH_PROCESSOR "alpha"
    #elif defined(Q_PROCESSOR_ARM_32)
    # define ARCH_PROCESSOR "arm"
    #elif defined(Q_PROCESSOR_ARM_64)
    # define ARCH_PROCESSOR "arm64"
    #elif defined(Q_PROCESSOR_AVR32)
    # define ARCH_PROCESSOR "avr32"
    #elif defined(Q_PROCESSOR_BLACKFIN)
    # define ARCH_PROCESSOR "bfin"
    #elif defined(Q_PROCESSOR_X86_32)
    # define ARCH_PROCESSOR "i386"
    #elif defined(Q_PROCESSOR_X86_64)
    # define ARCH_PROCESSOR "x86_64"
    #elif defined(Q_PROCESSOR_IA64)
    # define ARCH_PROCESSOR "ia64"
    #elif defined(Q_PROCESSOR_MIPS_64)
    # define ARCH_PROCESSOR "mips64"
    #elif defined(Q_PROCESSOR_MIPS)
    # define ARCH_PROCESSOR "mips"
    #elif defined(Q_PROCESSOR_POWER_32)
    # define ARCH_PROCESSOR "power"
    #elif defined(Q_PROCESSOR_POWER_64)
    # define ARCH_PROCESSOR "power64"
    #elif defined(Q_PROCESSOR_S390_X)
    # define ARCH_PROCESSOR "s390x"
    #elif defined(Q_PROCESSOR_S390)
    # define ARCH_PROCESSOR "s390"
    #elif defined(Q_PROCESSOR_SH)
    # define ARCH_PROCESSOR "sh"
    #elif defined(Q_PROCESSORS_SPARC_64)
    # define ARCH_PROCESSOR "sparc64"
    #elif defined(Q_PROCESSOR_SPARC_V9)
    # define ARCH_PROCESSOR "sparcv9"
    #elif defined(Q_PROCESSOR_SPARC)
    # define ARCH_PROCESSOR "sparc"
    #else
    # define ARCH_PROCESSOR "unknown"
    #endif

处理器对应的宏有固定的格式，如下所示。

// qprocessordetection.h    
        Q_PROCESSOR_{FAMILY}
        Q_PROCESSOR_{FAMILY}_{VARIANT}
        Q_PROCESSOR_{FAMILY}_{REVISION}
    
    // qprocessordetection.h    
    // ... other arches
    /*
    ARM family, known revisions: V5, V6, V7, V8
    ARM is bi-endian, detect using __ARMEL__ or __ARMEB__
    
    X86 family, known variants: 32- and 64-bit
    X86 is little-endian
    /*
    #elif defined(__i386) || defined(__i386__) || defined(_M_IX86)
    # define Q_PROCESSOR_X86_32
    # define Q_BYTE_ORDER Q_LITTLE_ENDIAN
    # define Q_PROCESSOR_WORDSIZE 4
    # if defined(_M_IX86)
    # define Q_PROCESSOR_X86 (_M_IX86/100)
    # elif defined(__i686__) || defined(__athlon__) || defined(__SSE__) || defined(__pentiumpro__)
    # define Q_PROCESSOR_X86 6
    # elif defined(__i586__) || defined(__k6__) || defined(__pentium__)
    # define Q_PROCESSOR_X86 5
    # elif defined(__i486__) || defined(__80486__)
    # define Q_PROCESSOR_X86 4
    # else
    # define Q_PROCESSOR_X86 3
    # endif
    #elif defined(__x86_64) || defined(__x86_64__) || defined(__amd64) || defined(_M_X64)
    # define Q_PROCESSOR_X86 6
    # define Q_PROCESSOR_X86_64
    # define Q_BYTE_ORDER Q_LITTLE_ENDIAN
    # define Q_PROCESSOR_WORDSIZE 8
    // ... other arches

## 7、arch endian ##

大小端字节序（ARCH\_ENDIANNESS）定义如下所示。

// archdetect.cpp
    // endianness
    #if Q_BYTE_ORDER == Q_LITTLE_ENDIAN
    # define ARCH_ENDIANNESS "little_endian"
    #elif Q_BYTE_ORDER == Q_BIG_ENDIAN
    # define ARCH_ENDIANNESS "big_endian"
    #endif
    
    // qprocessordetection.h 
    /* Machine byte-order, reuse preprocessor provided macros when available */
    #if defined(__ORDER_BIG_ENDIAN__)
    # define Q_BIG_ENDIAN __ORDER_BIG_ENDIAN__
    #else
    # define Q_BIG_ENDIAN 4321
    #endif
    #if defined(__ORDER_LITTLE_ENDIAN__)
    # define Q_LITTLE_ENDIAN __ORDER_LITTLE_ENDIAN__
    #else
    # define Q_LITTLE_ENDIAN 1234
    #endif
    
    // qprocessordetection.h 
    /* NOTE: GCC 4.6 added __BYTE_ORDER__, __ORDER_BIG_ENDIAN__, __ORDER_LITTLE_ENDIAN__ and __ORDER_PDP_ENDIAN__ in SVN r165881. If you are using GCC 4.6 or newer, this code will properly detect your target byte order; if you are not, and the __LITTLE_ENDIAN__ or __BIG_ENDIAN__ macros are not defined, then this code will fail to detect the target byte order. */
    // Some processors support either endian format, try to detect which we are using.
    #if !defined(Q_BYTE_ORDER)
    # if defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == Q_BIG_ENDIAN || __BYTE_ORDER__ == Q_LITTLE_ENDIAN)
    // Reuse __BYTE_ORDER__ as-is, since our Q_*_ENDIAN #defines match the preprocessor defaults
    # define Q_BYTE_ORDER __BYTE_ORDER__
    # elif defined(__BIG_ENDIAN__) || defined(_big_endian__) || defined(_BIG_ENDIAN)
    # define Q_BYTE_ORDER Q_BIG_ENDIAN
    # elif defined(__LITTLE_ENDIAN__) || defined(_little_endian__) || defined(_LITTLE_ENDIAN) \
            || defined(WINAPI_FAMILY) // WinRT is always little-endian according to MSDN.
    # define Q_BYTE_ORDER Q_LITTLE_ENDIAN
    # else
    # error "Unable to determine byte order!"
    # endif
    #endif

## 8、arch pointer ##

指针大小（ARCH\_POINTER）定义如下所示。

// archdetect.cpp
    // pointer type
    #if defined(Q_OS_WIN64) || (defined(Q_OS_WINRT) && defined(_M_X64))
    # define ARCH_POINTER "llp64"
    #elif defined(__LP64__) || QT_POINTER_SIZE - 0 == 8
    # define ARCH_POINTER "lp64"
    #else
    # define ARCH_POINTER "ilp32"
    #endif
    
    // qprocessordetection.h 
    /* Size of a pointer and the machine register size. We detect a 64-bit system by: * GCC and compatible compilers (Clang, ICC on OS X and Windows) always define __SIZEOF_POINTER__. This catches all known cases of ILP32 builds on 64-bit processors. * Most other Unix compilers define __LP64__ or _LP64 on 64-bit mode (Long and Pointer 64-bit) * If Q_PROCESSOR_WORDSIZE was defined above, it's assumed to match the pointer size. Otherwise, we assume to be 32-bit and then check in qglobal.cpp that it is right. */
    
    #if defined __SIZEOF_POINTER__
    # define QT_POINTER_SIZE __SIZEOF_POINTER__
    #elif defined(__LP64__) || defined(_LP64)
    # define QT_POINTER_SIZE 8
    #elif defined(Q_PROCESSOR_WORDSIZE)
    # define QT_POINTER_SIZE Q_PROCESSOR_WORDSIZE
    #else
    # define QT_POINTER_SIZE 4
    #endif

## 9、arch coordinate ##

浮点数精度（ARCH\_COORD\_TYPE）定义如下所示。

// archdetect.cpp
    // qreal type, if not double (includes the dash)
    #ifdef QT_COORD_TYPE_STRING
    # define ARCH_COORD_TYPE "-qreal_" QT_COORD_TYPE_STRING
    #else
    # define ARCH_COORD_TYPE ""
    #endif

## 10、arch abi ##

程序二进制接口相关的软、硬浮点（ARCH\_ABI）定义如下所示。

// archdetect.cpp
    // secondary: ABI string (includes the dash)
    #if defined(__ARM_EABI__) || defined(__mips_eabi)
    # define ARCH_ABI1 "-eabi"
    #elif defined(_MIPS_SIM)
    # if _MIPS_SIM == _ABIO32
    # define ARCH_ABI1 "-o32"
    # elif _MIPS_SIM == _ABIN32
    # define ARCH_ABI1 "-n32"
    # elif _MIPS_SIM == _ABI64
    # define ARCH_ABI1 "-n64"
    # elif _MIPS_SIM == _ABIO64
    # define ARCH_ABI1 "-o64"
    # endif
    #else
    # define ARCH_ABI1 ""
    #endif
    #if defined(__ARM_PCS_VFP) || defined(__mips_hard_float)
    // Use "-hardfloat" for platforms that usually have no FPUs
    // (and for the platforms which had "-hardfloat" before we established the rule)
    # define ARCH_ABI2 "-hardfloat"
    #elif defined(_SOFT_FLOAT)
    // Use "-softfloat" for architectures that usually have FPUs
    # define ARCH_ABI2 "-softfloat"
    #else
    # define ARCH_ABI2 ""
    #endif
    
    #define ARCH_ABI ARCH_ABI1 ARCH_ABI2

[https_isocpp.org_std_standing-documents_sd-6-sg10-feature-test-recommendations]: https://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations