使用宏检测gcc而不是msvc / clang [英] Detect gcc as opposed to msvc / clang with macro

问题描述

我正在研究一个已经用gcc和msvc构建的项目。我们最近也开始使用clang进行构建。

代码中有一些部分，其中包含特定于平台的事情：

  #ifndef _WIN32 
 //在msvc中忽略
 #endif 
  

由于gcc以前是唯一的非Windows版本，这相当于说只为gcc做这个。但现在它的意思是这样做只适用于gcc和clang。

然而，仍然存在一些情况，我想专门为gcc处理某些事情， 。是否有一种简单而强大的方法来检测gcc，即：

  #ifdef ??? 
 //这样做*仅*用于gcc 
 #endif 
  

解决方案

  __ GNUC__ 
 __GNUC_MINOR__ 
 __GNUC_PATCHLEVEL__ 
  

这些宏由所有使用C预处理器的GNU编译器定义：C，C ++，Objective-C和Fortran。它们的值是编译器的主版本，次版本和补丁级别，作为整数常量。例如，GCC 3.2.1将把__GNUC__定义为3，__GNUC_MINOR__定义为2，__GNUC_PATCHLEVEL__定义为1.如果直接调用预处理器，也会定义这些宏。

另外：

  __ GNUG__ 
  

GNU C ++编译器对此进行了定义。测试它相当于测试（__GNUC__&& __cplusplus）。

来源

显然， clang 也使用它们。不过它也定义了：

$ pre code $ __ clang__
__clang_major__
__clang_minor__
__clang_patchlevel__

您可以这样做：

  #ifdef __GNUC__ 
 #ifndef __clang__ 
 ... 
  

或甚至更好（注意订单）：

  #if defined（__ clang__）
 .... 
 #elif defined（__ GNUC__）||定义（__ GNUG__）
 .... 
 #elif defined（_MSC_VER）
 .... 
  

I am working on a project that has been built with both gcc and msvc so far. We recently started building with clang as well.

There are some parts in the code, where platform-specific things are done:

#ifndef _WIN32
// ignore this in msvc
#endif

Since gcc has previously been the only non-windows build, this was equivalent to saying "do this only for gcc". But now it means "do this only for gcc and clang".

However there are still situations, where I would like to handle something specifically for gcc, and not for clang. Is there a simple and robust way to detect gcc, i.e.

#ifdef ???
// do this *only* for gcc
#endif

解决方案

__GNUC__
__GNUC_MINOR__
__GNUC_PATCHLEVEL__

These macros are defined by all GNU compilers that use the C preprocessor: C, C++, Objective-C and Fortran. Their values are the major version, minor version, and patch level of the compiler, as integer constants. For example, GCC 3.2.1 will define __GNUC__ to 3, __GNUC_MINOR__ to 2, and __GNUC_PATCHLEVEL__ to 1. These macros are also defined if you invoke the preprocessor directly.

Also:

__GNUG__

The GNU C++ compiler defines this. Testing it is equivalent to testing (__GNUC__ && __cplusplus).

Source

Apparently, clang uses them too. However it also defines:

__clang__
__clang_major__
__clang_minor__
__clang_patchlevel__

So you can do:

#ifdef __GNUC__
    #ifndef __clang__
...

Or even better (note the order):

#if defined(__clang__)
....
#elif defined(__GNUC__) || defined(__GNUG__)
....
#elif defined(_MSC_VER)
....

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