CMake 获取clang 版本

通过cmake set设置CMAKE_C_COMPILER/CMAKE_ASM_COMPILER/CMAKE_CXX_COMPILER，

  SET(CMAKE_C_COMPILER "xxx/clang")
  SET(CMAKE_ASM_COMPILER "xxx/clang")
  SET(CMAKE_CXX_COMPILER "xxx/clang++")

CMake 中与 clang相关的变量如下，但都是系统clang相关的，与前面设置clang无关:

• CLANG_VERSION_MAJOR,
• CLANG_VERSION_MINOR,
• CLANG_VERSION_PATCHLEVEL,
• and the combination of the above: CLANG_VERSION_STRING

可以通过下面的命令获取自定义的clang的版本

EXECUTE_PROCESS( COMMAND ${CMAKE_CXX_COMPILER} --version OUTPUT_VARIABLE clang_full_version_string )
string (REGEX REPLACE ".*clang version ([0-9]+\.[0-9]+).*" "\1" CLANG_VERSION_STRING ${clang_full_version_string})
if (CLANG_VERSION_STRING VERSION_GREATER 3.1)
  ...
endif ()

[1] https://stackoverflow.com/questions/16150888/cmake-branch-on-clang-version