Florian Weimer wrote:
>
> Levente Farkas <[EMAIL PROTECTED]> writes:
>
> > the followning simple code can prodcuce non-gnu both on red hat 6.2 and
> > 7.0 (with the default gcc) at the same time with the latest cvs gcc
> > it's print gnu. what is the difference and how can I force gcc to
> > define _GNU_SOURCE (-D_GNU_SOURCE seems to be a solution but I don't
> > know whether is there any reason that it's not defined by default or not)?
>
> When you use the GNU C Library, you have to define _GNU_SOURCE if you
> want to use certain extensions. These extensions are not available on
> some non-GNU systems; the idea is that this prevents you from
> accidently using them and making your software less portable.
>
> It's even documented in the GNU C Library manual ("Feature Test
> Macros"):
>
> | - Macro: _GNU_SOURCE
> | If you define this macro, everything is included: ISO C89,
> | ISO C99, POSIX.1, POSIX.2, BSD, SVID, X/Open, LFS, and GNU
> | extensions. In the cases where POSIX.1 conflicts with BSD, the
> | POSIX definitions take precedence.
>
> BTW: This hasn't much to do with GCC (the compiler itself), so
> [EMAIL PROTECTED] is not appropriate for this kind of discussion.
this's not that simple since if I try the current gcc
(http://www.codesourcery.com/gcc-snapshots/) with the following configure
options (and I assume there is not any sepcial in this):
----------------------
configure --prefix=/tmp/gcc-20001124-root/usr/local --enable-shared
--enable-threads --disable-checking i386-pc-linux-gnu
----------------------
than it's produce a gcc/g++ which DO define _GNU_SOURCE! why ? or why
redhat's gcc doesn't define it ??? what other macros defined by the
default and rh's gcc ?
what's more if redhat use their gcc (which doesn't define _GNU_SOURCE)
to compile other packages like glibc than it can cause further problems
eg. I can't use those "extended" features even if I define _GNU_SOURCE
in my source (but not defined is compiled libs). am I wrong ?
-- Levente http://petition.eurolinux.org/index_html
"The only thing worse than not knowing the truth is
ruining the bliss of ignorance."
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