Prototype __P

[uri <urishe@mail.inter.net.il>]

Can somebody explain me exactly,why  defined  "__P(argc) " ( at
<sys/cdefs.h>) ?
I was thinking it something to do with variable number of arguments ,
but the following doesn't match my previous thougths :

extern int readdir_r __P ((DIR *__dirp, struct dirent *__entry,
                           struct dirent **__result));

So , what __P(argc) supposed to do ?


Thanks a lot,
Uri