Re: [PATCH liburing 0/5] multishot recvmsg docs and example

[Ammar Faizi <ammarfaizi2@gnuweeb.org>]

On 7/27/22 5:11 PM, Ammar Faizi wrote:
> So -D_GNU_SOURCE is the culprit. It seems to be unavoidable as
> the warn seems to be compiler specific or something. Maybe that
> _GNU_SOURCE patches the definition of bind().

I did:

   gcc -E -D_GNU_SOURCE test.c -o xtest.c

and examined the xtest.c output.

So basically when we use _GNU_SOURCE, sometimes the declaration of
bind() is like this:

extern int bind (int __fd, __CONST_SOCKADDR_ARG __addr, socklen_t __len)
      __attribute__ ((__nothrow__ , __leaf__));

With __CONST_SOCKADDR_ARG being a union:

typedef union {
     const struct sockaddr *__restrict __sockaddr__;
     const struct sockaddr_at *__restrict __sockaddr_at__;
     const struct sockaddr_ax25 *__restrict __sockaddr_ax25__;
     const struct sockaddr_dl *__restrict __sockaddr_dl__;
     const struct sockaddr_eon *__restrict __sockaddr_eon__;
     const struct sockaddr_in *__restrict __sockaddr_in__;
     const struct sockaddr_in6 *__restrict __sockaddr_in6__;
     const struct sockaddr_inarp *__restrict __sockaddr_inarp__;
     const struct sockaddr_ipx *__restrict __sockaddr_ipx__;
     const struct sockaddr_iso *__restrict __sockaddr_iso__;
     const struct sockaddr_ns *__restrict __sockaddr_ns__;
     const struct sockaddr_un *__restrict __sockaddr_un__;
     const struct sockaddr_x25 *__restrict __sockaddr_x25__;
} __CONST_SOCKADDR_ARG __attribute__ ((__transparent_union__));

But not all header file included by the compiler has this union stuff.
When it doesn't, it will throw a warning like that.

-- 
Ammar Faizi