expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘struct’

这篇准备长期更新…

1.在编译时遇到错误

错误： expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘struct’
src/cli_socket_handle.c: 在函数‘client_login’中:
...

• 这种错误第一次遇到肯定很懵逼，根据多年的调试经验，很大可能是某个头文件不小心多打了某些没有意义的字符串，比如（倒数第二行多了个send）：

  #ifndef CLI_SOCKET_HANDLE_H
  #define CLI_SOCKET_HANDLE_H
  #include "format.h"
  
  int send_file_head(int sockfd);
  send
  #endif //!CLI_SOCKET_HANDLE_H
  

2.下面这个错误

/usr/include/fcntl.h:211:12: 错误： 为形参‘posix_fadvise’指定了存储类
/usr/include/fcntl.h:233:12: 错误： 为形参‘posix_fallocate’指定了存储类
In file included from src/cli_socket_handle.c:15:0:
./libs/md5_sha2/include/sha2.h:22:2: 错误： 为形参‘Sha256State’指定了存储类
./libs/md5_sha2/include/sha2.h:25:17: 错误： expected declaration specifiers or ‘...’ before ‘Sha256State’
./libs/md5_sha2/include/sha2.h:26:18: 错误： expected declaration specifiers or ‘...’ before ‘Sha256State’
./libs/md5_sha2/include/sha2.h:27:17: 错误： expected declaration specifiers or ‘...’ before ‘Sha256State’
./libs/md5_sha2/include/sha2.h:28:19: 错误： expected declaration specifiers or ‘...’ before ‘Sha256State’
./libs/md5_sha2/include/sha2.h:32:15: 错误： 为形参‘Sha256Callback’指定了存储类
./libs/md5_sha2/include/sha2.h:33:22: 错误： expected declaration specifiers or ‘...’ before ‘Sha256Callback’
./libs/md5_sha2/include/sha2.h:37:21: 错误： expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘Sha224State’
./libs/md5_sha2/include/sha2.h:39:17: 错误： expected declaration specifiers or ‘...’ before ‘Sha256State’
./libs/md5_sha2/include/sha2.h:42:19: 错误： 未知的类型名‘Sha224State’
。。。

• 别着急，这种大部分是因为头文件某个函数后面忘记加分号了，比如（倒数第二行函数声明后少了分号发现没）：

  #ifndef CLI_SOCKET_HANDLE_H
  #define CLI_SOCKET_HANDLE_H
  #include "format.h"
  
  int send_file_head(int sockfd)
  #endif //!CLI_SOCKET_HANDLE_H