1  #if __has_include (<alloca.h>)
       2  #  include <alloca.h>
       3  #endif
       4  
       5  #ifndef alloca
       6     /* Simulate a definition in a system header. */
       7  #  pragma GCC system_header
       8  #  define alloca(n) __builtin_alloca (n)
       9  #endif