[vox-tech] compiler error causing me great sadness

[Ken Herron]

--On Wednesday, September 29, 2004 11:06:50 PM -0400 Peter Jay Salzman 
<p at 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