gcc struct 赋值警告初始化器周围缺少大括号

Question

以下

#include <net/route.h>
#include <netinet/in.h>
int main(){
  struct rtentry e={};
  *((struct sockaddr_in*)(&(e.rt_genmask)))=(struct sockaddr_in){.sin_family=AF_INET,.sin_port=0,.sin_addr=INADDR_ANY};
  return 0;
}

发出警告 (gcc -std=c11 -Wall test.c)

test.c:5:45: warning: missing braces around initializer [-Wmissing-braces]
    5 |   *((struct sockaddr_in*)(&(e.rt_genmask)))=(struct sockaddr_in){.sin_family=AF_INET,.sin_port=0,.sin_addr=INADDR_ANY};
      |                                             ^
                                         ^

为什么？我该如何修复代码？

Answer 1

INADDR_ANY is macro defined.
in_addr 是一个包装值的结构。您需要使用 .sin_addr={INADDR_ANY} 来确保它由值 INADDR_ANY.

           struct sockaddr_in {
               sa_family_t    sin_family; /* address family: AF_INET */
               in_port_t      sin_port;   /* port in network byte order */
               struct in_addr sin_addr;   /* internet address */
           };

           /* Internet address. */
           struct in_addr {
               uint32_t       s_addr;     /* address in network byte order */
           };

固定：https://godbolt.org/z/xM8r1E

#include <net/route.h>

int main(void) {
    struct rtentry e={};
    *(struct sockaddr_in*)(&(e.rt_dst))=(struct sockaddr_in){
    .sin_family=AF_INET,
    .sin_port=0,
    .sin_addr={INADDR_ANY}
    };
    return 0;
}

gcc struct 赋值警告初始化器周围缺少大括号

gcc struct assignment warning missing braces around initializer

c

gcc

struct

gcc-warning