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警告:“…”的声明在此函数外不可见[-Wvisibility]

criw · 技术社区 · 6 年前

首先,我在谷歌上搜索了错误并阅读了以下答案:

问题就在这两个结构之间, prx_data_s 存储通用数据和 prx_ops_s 它定义指向将使用该数据的函数的指针。

prx_数据.h

#ifndef PRX_EXAMPLE_DATA_H
#define PRX_EXAMPLE_DATA_H

#include "prx_ops.h"

struct prx_data_s {
    enum  prx_op_t op;
    char *keyquery;
};

char *get_query(struct prx_data_s *dt);

#endif

prx_数据.c

#include "prx_data.h"

char *get_query(struct prx_data_s *dt)
{
    return dt->keyquery;
}

prx_ops.h公司

#ifndef PRX_EXAMPLE_OPS_H
#define PRX_EXAMPLE_OPS_H

#include "prx_data.h"

enum prx_op_t {
    PRX_EXAMPLE_OP = 2
};

struct prx_ops_s {
    int (*dec) (struct prx_data_s *);
};

#endif

我试图用以下方法编译上面示例中的对象:

clang -c prx_data.c -o prx_data.o -std=c11 -g -Wall

这是输出错误:

In file included from prx_data.c:1:
In file included from ./prx_data.h:4:
./prx_ops.h:11:24: warning: declaration of 'struct prx_data_s' will not be visible outside of this function [-Wvisibility]
int (*dec) (struct prx_data_s *);
                   ^

欢迎所有帮助,谢谢:)

2 回复 | 直到 6 年前

Gerhardh 6 年前

头部中的循环依赖项有问题:

prx_data.h:

#include "prx_ops.h" <<< Here we do not yet see the struct definition

    prx_ops.h:

    #include "prx_data.h"  <<<< Nothing will be included due to inclusion guards.

    struct prx_ops_s {
       int (*dec) (struct prx_data_s *);  <<<< Here a new struct type is declared.
    };

later back in prx_data.h:

struct prx_data_s {
  enum  prx_op_t op;
  char *keyquery;
};