错误：‘；的类型冲突；wstat&x2019；在gcc中

我从以下文档中复制了此程序：

---

据我所知，

wstat

定义了两次。这是否意味着文档不正确？以及如何修复它？

是的，代码刚刚被破坏。我不知道

union wait wstat的意图是什么。可能是文档作者的复制粘贴错误。谁知道呢。依我看，代码一般写得很差

无论如何，下面是代码实际要做的：

int wstat;
pid_t pid;

while (1) {
    pid = wait3(&wstat, WNOHANG, NULL);
    if (pid == 0 || pid == -1)
        return;
    printf("Return code: %d\n", wstat);
}

main.c: In function ‘proc_exit’:
main.c:9:13: error: conflicting types for ‘wstat’
  union wait wstat;
             ^~~~~
main.c:8:6: note: previous declaration of ‘wstat’ was here
  int wstat;
      ^~~~~
main.c:9:13: error: storage size of ‘wstat’ isn’t known
  union wait wstat;
             ^~~~~
main.c:12:9: error: ‘TRUE’ undeclared (first use in this function)
  while (TRUE) {

int wstat;
pid_t pid;

while (1) {
    pid = wait3(&wstat, WNOHANG, NULL);
    if (pid == 0 || pid == -1)
        return;
    printf("Return code: %d\n", wstat);
}