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Re: [vox-tech] compiler error causing me great sadness
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Re: [vox-tech] compiler error causing me great sadness



--On Wednesday, September 29, 2004 11:06:50 PM -0400 Peter Jay Salzman <p@dirac.org> wrote:

   #ifndef _FSIGNAL_H_
   #define _FSIGNAL_H_

   #define __GNU_SOURCE
   #include <signal.h>
   #include <stdio.h>
I think you want _GNU_SOURCE there, not __GNU_SOURCE. Though "#define _POSIX_C_SOURCE 199309L" should be adequate.


It's kind of a mess, but when I include __USE_POSIX and
__USE_POSIX199309, I get "constant redefinition" errors.  So instead, I
add:
You aren't supposed to define the __USE_* macros yourself. See <features.h>. Actually, when I ran your fsignal.h through "gcc -E" the postprocessed C contained the siginfo_t definition. If you're not getting it, then perhaps you've set one of the standard-selection macros to an old standard such that __USE_POSIX199309 isn't supposed to be defined.


How am I supposed to figure out how to get a definition for siginfo_t?
Am I really supposed to grub around in the libc header files???
No, of course not. There are standards for this stuff, though programming books don't always do a good job of explaining them. For example, on a modern system running:

echo '#include <signal.h>' | gcc -E -

should get you a copy of the siginfo_t definition, but:

echo '#include <signal.h>' | gcc -E -D_POSIX_SOURCE -

because _POSIX_SOURCE implies a specific revision of the POSIX standard that predates the siginfo_t type.


--
Ken Herron
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