Hi!

I've currently some trouble with a 3rd party application (Python 2.3/CVS)
which sets:
_POSIX_C_SOURCE 200112L
_XOPEN_SOURCE 600
_XOPEN_SOURCE_EXTENDED 1
by default. But, it still uses eg. rpc, which won't compile, because u_int
isn't defined in the POSIX case. Solaris solves such issues by letting the
user define __EXTENSIONS__ to get the extended system interfaces.
Eg. (Solaris 8 sys/types.h):
#if defined(__EXTENSIONS__) || \
        (!defined(_POSIX_C_SOURCE) && !defined(_XOPEN_SOURCE))
[...]

Linux has _GNU_SOURCE for such cases. I didn't find something like that on
my 1.6R system.
IMHO is important to set something like a "POSIX++" environment, because
it's _a lot_ easier to setup a CFLAGS with  __EXTENSIONS__=1 in the
environment and run "configure" than changing 3rd party code.

A quick glance at
http://www.opengroup.org/onlinepubs/007904975/basedefs/xbd_chap02.html
showed nothing that would speak against such a define.

Regards,
Marc

mundus es fabula