conftest.c

   1 #include <stdio.h>
   2
   3 int main(int argc, char *argv[])
   4 {
   5     switch(argc == 2 ? argv[1][0] : 0) {
   6 #ifdef __GNUC__
   7         case 'v':
   8             printf("%d\n", __GNUC__);
   9             break;
  10         case 'm':
  11             printf("%d\n", __GNUC_MINOR__);
  12             break;
  13 #else
  14         case 'v':
  15         case 'm':
  16             puts("0");
  17             break;
  18 #endif
  19         case 'b':
  20         {
  21             volatile unsigned foo = 0x01234567;
  22             puts(*(unsigned char*)&foo == 0x67 ? "no" : "yes");
  23             break;
  24         }
  25         case -1:
  26             /* to test -Wno-unused-result */
  27             fread(NULL, 1, 1, NULL);
  28             break;
  29     }
  30     return 0;
  31 }