我如何在编译时测试GCC的当前版本？ [英] How do I test at compile time the current version of GCC?

问题描述

我想包括根据GCC的版本不同的文件。更多precisely我想写：

I would like to include a different file depending on the version of GCC. More precisely I want to write:

#if GCC_VERSION >= 4.2
#  include <unordered_map>
#  define EXT std
#elif GCC_VERSION >= 4
#  include <tr1/unordered_map>
#  define EXT std
#else
#  include <ext/hash_map>
#  define unordered_map __gnu_cxx::hash_map
#  define EXT __gnu_cxx
#endif

我不前3.2不在乎GCC。

I don't care about gcc before 3.2.

注意：我是pretty请务必在preprocessing时间为定义的变量，我无法再找到它。

Note: I am pretty sure there is a variable defined at preprocessing time for that, I just can't find it again.

推荐答案

好吧，经过搜索，它一个人这么做它使用 __ GNUC_ preREQ可能的方式在 features.h 定义。

Ok, after more searches, it one possible way of doing it is using __GNUC_PREREQ defined in features.h.

#ifdef __GNUC__
#  include <features.h>
#  if __GNUC_PREREQ(4,0)
//      If  gcc_version >= 4.0
#  elif __GNUC_PREREQ(3,2)
//       If gcc_version >= 3.2
#  else
//       Else
#  endif
#else
//    If not gcc
#endif

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