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

[Simon Marchi <simon.marchi@polymtl.ca>]

On 2018-10-30 17:42, Sergio Durigan Junior wrote:
> 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.

> gdb/ChangeLog:
> 2018-10-30  Sergio Durigan Junior  <sergiodj@redhat.com>
> 
> 	PR gdb/23835
> 	* common/common-defs.h: Don't redefine _FORTIFY_SOURCE is it's
> 	already defined.
> ---
>  gdb/ChangeLog            | 6 ++++++
>  gdb/common/common-defs.h | 5 +++--
>  2 files changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/gdb/ChangeLog b/gdb/ChangeLog
> index 940300f95a..239d7e16c2 100644
> --- a/gdb/ChangeLog
> +++ b/gdb/ChangeLog
> @@ -1,3 +1,9 @@
> +2018-10-30  Sergio Durigan Junior  <sergiodj@redhat.com>
> +
> +	PR gdb/23835
> +	* common/common-defs.h: Don't redefine _FORTIFY_SOURCE is it's

is -> if.

Simon