[Yaffs] opaque

Hi,
1) what is the purpose of the line "typedef struct __opaque yaffs_DIR"
- more specifically what does the opaque keyword do? I'm not trying
to turn this mailing list into a tutorial for C, but in my 7 years or
so of C programming I've never encountered the __opaque keyword.
I cannot find much info on it on the web or in C/C++ books.

2) I get the following warning at the end of this typedef:
"yaffsfs.h:153: warning: useless keyword or type name in empty
declaration"
typedef struct yaffs_dirent
{
    long d_ino;                 /* inode number */
    off_t d_off;                /* offset to this dirent */
    unsigned short d_reclen;    /* length of this d_name */
    char d_name [NAME_MAX+1];   /* file name (null-terminated) */
};

I cannot recall that I got this warning before but now I also cannot
see what is causing it.

regards
Johann Kok

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