Re: [PATCH] Fix PR gdb/23835: Don't redefine _FORTIFY_SOURCE if it's already defined

[Joel Brobecker <brobecker@adacore.com>]

> > Gentoo has a local GCC patch which always defines _FORTIFY_SOURCE=2.
> > This causes a build problem when building GDB there, because
> > "common/common-defs.h" also defines _FORTIFY_SOURCE=2:
> > 
> >     CXX    gdb.o
> >   In file included from ../../gdb/defs.h:28:0,
> > 		   from ../../gdb/gdb.c:19:
> >   ../../gdb/common/common-defs.h:71:0: error: "_FORTIFY_SOURCE"
> > redefined [-Werror]
> >    #define _FORTIFY_SOURCE 2
> > 
> >   <built-in>: note: this is the location of the previous definition
> >   cc1plus: all warnings being treated as errors
> >   make[2]: *** [Makefile:1619: gdb.o] Error 1
> > 
> > Even though it is questionable whether Gentoo's approach is the
> > correct one:
> > 
> >   https://jira.mongodb.org/browse/SERVER-29982
> >   https://bugs.gentoo.org/621036
> > 
> > it is still possible for GDB to be a bit more robust here and make
> > sure it just defines _FORTIFY_SOURCE if it hasn't been defined
> > already.  This patch does that.
> > 
> > Tested by rebuilding and making sure the macro was defined.
> 
> I think it makes sense, it also gives the user the possibility to override
> it, if they don't like our value.  Give it a few days to give others a
> change to respond.  If you don't hear anything in ~1 week, please go ahead
> and push.

Good point about allowing the user to override it.

The patch looks OK to me too.

-- 
Joel