#include <stdio.h>
#define COMPAT_P __builtin_types_compatible_p
#define COMPAT_S(a,b) ((char*[]){"false","true"}[COMPAT_P(a,b)])
#define COMPAT_PP(a,b) {printf("%s\n",COMPAT_S(a,b));}

int main(void)
{
  typedef int a_t[3];

  COMPAT_PP(a_t[4],int[4][3]);
  COMPAT_PP(a_t[4],int[3][4]);

  return 0;
}

#if 0
[m@monire m]$ ./types_compat_p
true
false
#endif