1  #include <stdio.h>
       2  #include <stdlib.h>
       3  #include <libc-diag.h>
       4  
       5  int
       6  main(int arc, char *argv[])
       7  {
       8    int res;
       9    unsigned int val;
      10  
      11    FILE *fp = fopen ("/dev/null", "r");
      12  
      13    val = 0;
      14    res = fscanf(fp, "%n", &val);
      15  
      16    printf("Result of fscanf %%n = %d\n", res);
      17    printf("Scanned format = %d\n", val);
      18  
      19    /* We're testing exactly the case the warning is for.  */
      20    DIAG_PUSH_NEEDS_COMMENT;
      21    DIAG_IGNORE_NEEDS_COMMENT (4.9, "-Wformat-zero-length");
      22  
      23    res = fscanf(fp, "");
      24  
      25    DIAG_POP_NEEDS_COMMENT;
      26  
      27    printf("Result of fscanf \"\" = %d\n", res);
      28    if (res != 0)
      29      abort ();
      30  
      31    res = fscanf(fp, "BLURB");
      32    printf("Result of fscanf \"BLURB\" = %d\n", res);
      33    if (res >= 0)
      34      abort ();
      35  
      36    fclose (fp);
      37  
      38    return 0;
      39    return 0;
      40  }