http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59935
--- Comment #1 from Markus Trippelsdorf <trippels at gcc dot gnu.org> --- markus@x4 /tmp % cat foo.c #define _GNU_SOURCE markus@x4 /tmp % gcc -D_GNU_SOURCE -c foo.c foo.c:1:0: warning: "_GNU_SOURCE" redefined [enabled by default] #define _GNU_SOURCE ^ <command-line>:0:0: note: this is the location of the previous definition foo.c:1:0: internal compiler error: Segmentation fault