I am questioning how this code compiled even though struct iwreq does not have ifr_name as a member

I wrote very simple code using struct iwreq. Also, I expected this will be error. But it is compiled and works.

I looked inside linux/wireless.h which has the definition of struct iwreq. And the iwreq does not ifr_name as a member.

Would someone can give me an idea? Here is the simple code.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <linux/wireless.h>

int main(void)
{
   char *intf = "eth0";
   struct iwreq iwr;

   strncpy(iwr.ifr_name, intf, sizeof(iwr.ifr_name));

   printf("main : intf = %s, iwr.ifr_name = %s\n", intf, iwr.ifr_name);
   return 0;
}