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Bug#108663: funky bug



On Wed, Sep 26, 2001 at 01:20:05PM -0400, Matt Zimmerman wrote:
> > If I do
> > 
> > g++ -E -c -D_BSD_SOURCE /usr/include/netinet/udp.h
> > 
> > then I can see the BSD definitions (uh_sport etc), both on i386 and hppa.
> > But if I do
> > 
> > g++-3.0 -E -c udphdrtest.c
> > 
> > then I see the non-BSD definition on both. Works ok with g++ 2.95.4 on
> > i386, but hppa doesn't have g* 2.x.
> > 
> > Looking at the output of g++{,-3.0} -c -E -dM, version 3 fails
> > to define __FAVOR_BSD, which the header file uses to choose the
> > definition. <features.h> only #defines __FAVOR_BSD if _GNU_SOURCE
> > is undefined; on g++ 3.0, _GNU_SOURCE is defined.
> > 
> > touch blah.c
> > g++ -c -E -dM blah.c       shows no _GNU_SOURCE;
> > g++-3.0 -c -E -dM blash.c  shows _GNU_SOURCE, hence no __FAVOR_BSD
> > 
> > I'm not sure if there is a bug in the library or not (I can't work out
> > where _GNU_SOURCE is being defined; it's only with g++-3.0, not with
> > gcc-3.0, too). You could #undef _GNU_SOURCE in your source though;
> > that might be a hack.
> 
> Thanks for the analysis.  I can't find anyplace where _GNU_SOURCE is
> defined, even conditionally, in /usr/include or /usr/lib/gcc-lib.  It isn't
> defined by cpp (cpp -dM /dev/null doesn't show it).  Hopefully the GCC
> maintainers will have some ideas.

-D_GNU_SOURCE is absolutely necessary to use libstdc++ v3.0.  Thus, G++
3.0 automatically defines it.

You're not going to be able to do anything about that :)  I recommend
you tweak the use of your structure to not rely on __FAVOR_BSD.

-- 
Daniel Jacobowitz                           Carnegie Mellon University
MontaVista Software                         Debian GNU/Linux Developer



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