On Tue, Dec 25, 2001 at 11:51:13PM -0800, Johnny C. Lam wrote:

 > In looking through the source files in /usr/xsrc/xfree (XFree86-4.1.0 sources),
 > I saw something like the following in many files:
 > 
 > 	#define _POSIX_SOURCE
 > 	#include <signal.h>	/* includes <sys/featuretest.h> */
 > 	#undef _POSIX_SOURCE
 > 
 > Currently, after the indirect inclusion of <sys/featuretest.h> through
 > <signal.h>, the CPP macro _POSIX_C_SOURCE is always defined, whereas before,
 > it may have been defined depending what other headers were included before
 > the inclusion of <signal.h> that also included <sys/featuretest.h>.  In
 > particular, this causes xsrc/xfree/xc/programs/xdm/session.c to not build
 > on a 1.5ZA system from the latest i386 snapshot (20011222); session.c includes
 > dm.h which includes <setjmp.h> in exactly the way described above.  Should I
 > now be changing the lines to look like:
 > 
 > 	#define _POSIX_SOURCE
 > 	#include <signal.h>	/* includes <sys/featuretest.h> */
 > 	#undef _POSIX_SOURCE
 > 	#ifdef _POSIX_C_SOURCE
 > 	#undef _POSIX_C_SOURCE
 > 	#endif
 > 
 > or is some other solution recommended?

I think the real problem is <sys/featuretest.h> trying to be too clever.
<sys/featuretest.h> probably should not be defining _POSIX_C_SOURCE.  The
fact that our header files test for _POSIX_SOURCE in some places and
_POSIX_C_SOURCE in others is what caused me to make the change in the first
place; building of one of our toolchain components was failing because it
was including some header file which included <sys/featuretest.h>, then
#define'd _POSIX_SOURCE and included some other files.  The problem was:

	* _POSIX_SOURCE was defined when <sys/types.h> was pulled in,
	  so u_long was not typedef'd.

	* _POSIX_C_SOURCE was not defined when <unistd.h> was pulled
	  in (because <sys/featuretest.h> had already been included
	  indirectly earlier when _POSIX_SOURCE was not defined), so
	  the profil() prototype was provided, which used u_long,
	  which was not typedef'd.

The whole thing is kind of a mess.  But, looking at what xfree is doing,
I'd say it's also wrong, playing the _POSIX_SOURCE game its playing.

-- 
        -- Jason R. Thorpe <thorpej@wasabisystems.com>