Re: [ANNOUNCEMENT] NEW: {libtirpc/libtirpc1/libtirpc-devel}-0.2.1-1

[Corinna Vinschen <corinna-cygwin at cygwin dot com>]

On Aug 20 21:07, Charles Wilson wrote:
> On 8/20/2010 8:35 PM, Eric Blake wrote:
> > In file included from ././remote/qemu_protocol.h:9,
> >                  from remote/qemu_protocol.c:7:
> > /usr/include/tirpc/rpc/rpc.h:84: warning: redundant redeclaration of
> > 'bindresvport' [-Wredundant-decls]
> > /usr/include/netinet/in.h:21: warning: previous declaration of
> > 'bindresvport' was here
> > /usr/include/tirpc/rpc/rpc.h:95: warning: redundant redeclaration of
> > 'bindresvport_sa' [-Wredundant-decls]
> > /usr/include/netinet/in.h:22: warning: previous declaration of
> > 'bindresvport_sa' was here
> 
> Well, looking at linux, the declarations in netinet/in.h are guarded by
> #if defined __USE_MISC || defined __USE_GNU
> 
> These symbols are activated in (linux's) features.h by:
> #if defined _BSD_SOURCE || defined _SVID_SOURCE
> # define __USE_MISC     1
> #endif
> 
> #ifdef  _GNU_SOURCE
> # define __USE_GNU      1
> #endif
> 
> Given that the only *SOURCE flags supported by cygwin's headers are:
>      _BSD_SOURCE
>      _POSIX_SOURCE
>      _XOPEN_SOURCE
>      _GNU_SOURCE
> (and, the newlib headers don't employ the __USE_* indirection), I think
> the correct fix is to modify cygwin's netinet/in.h to add the following
> guard around the declaration of bindresvport and bindresvport_sa:
> 
> #if defined(_BSD_SOURCE) || defined(_GNU_SOURCE)
> 
> If you concur, I'll post a patch to that effect to cygwin-patches (we
> use our own header, not newlib's, for netinet/in.h).

This is not the right solution.

First, we don't support _BSD_SOURCE and _GNU_SOURCE, yet, since, as you
can see in the comment in /usr/include/features.h, the groundwork is
entirely missing.  The _POSIX_SOURCE is used in newlib in the first
place and we can and do use it as well.  _XOPEN_SOURCE is only barely
available for a few months now, but it's not actually used anywhere.

However bindresvport and bindresvport_sa are guarded, they are part of
the official system header netinet/in.h, and they exist in Cygwin.

On Linux, bindresvport and bindresvport6 are available by default,
*unless* you define something like _POSIX_SOURCE.  Since newlib/Cygwin
is missing the groundwork for a full-fledged features.h, your above
suggestion would result in declaring bindresvport/bindresvport_sa *only
if*  the user explicitely defines _BSD_SOURCE or _GNU_SOURCE on the
command line.  That's not feasible.

The question is, why does libtirpc declare the functions at all?  Does
it come with its own implementation?  Whether or not, I think the
problem are the libtirpc headers in the first place.

There's a similar case with krb5 headers, where gssrpc/rpc.h declares
bindresvport as well, but that's fixed by the gssrpc/rename.h header,
which is included automatically by gssrpc/rpc.h via gssrpc/types.h:

  #define bindresvport gssrpc_bindresvport

However, given that on Linux the declarations are available by default,
you will see the same warnings when using libtirpc's rpc/rpc.h header in
conjunction with netinet/in.h.  I just tested it on Fedora 13:

  $ gcc -c -I/usr/include/tirpc -Wredundant-decls x.c
  In file included from x.c:3:
  /usr/include/tirpc/rpc/rpc.h:84: warning: redundant redeclaration of âbindresvportâ
  /usr/include/netinet/in.h:440: note: previous declaration of âbindresvportâ was here

But note that this only occurs with -Wredundant-decls, which is not one
of the default warnings.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple