c - 宏返回编译警告中args的定义

Question

我有以下代码:

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

#define ARGS \
    struct kk *k, \
    struct kk1 *k1 \


struct kk {
    int a;
    int b;
    int (*f)(ARGS);
};

struct kk1 {
    char a;
    char b;
};


int main(int argc, char *argv[]) {
    struct kk pp = {.a = 1};
    printf("ddmsgstsssssssr ___(%d)__\n", pp.a);
    return 0;
}

当我使用 gcc -o test test.c 构建它时，我收到了以下警告:

test.c:6:9: warning: ‘struct kk1’ declared inside parameter list [enabled by default]
  struct kk1 *k1 \
         ^
test.c:12:11: note: in expansion of macro ‘ARGS’
  int (*f)(ARGS);
           ^
test.c:6:9: warning: its scope is only this definition or declaration, which is probably not what you want [enabled by default]
  struct kk1 *k1 \
         ^
test.c:12:11: note: in expansion of macro ‘ARGS’
  int (*f)(ARGS);
           ^

如何解决这个问题？

Answer 1

要么将 struct kk1 移动到 struct kk 之前，要么向前声明 struct kk1。如果您不想定义结构，则后者更优雅。

#define ARGS \
    struct kk *k, \
    struct kk1 *k1 \

struct kk1; /* this changed */
struct kk {
    int a;
    int b;
    int (*f)(ARGS);
};

struct kk1 {
    char a;
    char b;
};