On 08/23/2010 11:28 AM, John Calcote wrote:
Hi all,
I ran into an interesting issue today. Hoping some of you have some
insight for me. I needed to use a later addition to the pthreads spec -
pthread_mutexaddr_settype (in order to initialize a recursive mutex). To
use this function, you need to define __USE_UNIX98 before including
pthread.h - at least on my platform (opensuse 11.3 64-bit).
Are you using the AC_USE_SYSTEM_EXTENSIONS macro, prior to anything else
that probes the C compiler? If so, then that should be defining all
macros necessary to make the headers declare extensions such as
pthread_mutexaddr_settype (and if it isn't, then that's a bug in
AC_USE_SYSTEM_EXTENSIONS that we need to fix).
What is the correct approach for this situation? Should I simply define
__USE_UNIX98 in my source code because I need the associated
functionality? Is __USE_UNIX98 a widely used and understood macro?
(Google searches didn't really help me understand the proper use of this
macro.)
Generally, using AC_USE_SYSTEM_EXTENSIONS, then ensuring that your files
include <config.h> before any system headers, should be adequate without
you having to know whether the system spelled their extension guard as
__USE_UNIX98, _GNU_SOURCE, __EXTENSIONS__, or some other spelling.
--
Eric Blake ebl...@redhat.com +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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