gcc使用c11取消引用指向不完整类型的指针

Question

I am noob with c. I have error during compilation with --std=c11 and

#define _XOPEN_SOURCE 600

that is

dereferencing pointer to incomplete type

It does not appear with not --std=c11 and define. My code is like:

struct icmp* icmp;
char send_buffer[BSIZE];
...
icmp = (struct icmp *) send_buffer;
icmp->icmp_type = ICMP_ECHO;

and the error is:

icmp.c: In function ‘prepare_send_icmp’:
icmp.c:41:6: error: dereferencing pointer to incomplete type
  icmp->icmp_type = ICMP_ECHO;

It does not appear with no gcc flag --std=c11 how to repair it?

Answer 1

您的问题的答案是#define _GNU_SOURCE。