宏__CC_ARM 是MDK自带的, 在AC5中是__CC_ARM ,AC6中是__clang__。如下
AC5:
#if defined ( __ICCARM__ )
#elif defined ( __CC_ARM )
#endif
AC6 :
#if defined ( __ICCARM__ )
#pragma system_include /* treat file as system include file for MISRA check */
#elif defined (__clang__)
#pragma clang system_header /* treat file as system include file */
#endif