GCC 4.5 used to ignore ‘-R’, but GCC 4.6 rejects it:

--8<---------------cut here---------------start------------->8---
$ echo "int main () { return 0; }" > t.c

$ ./result/bin/gcc t.c -R/foo
gcc: unrecognized option '-R/foo'
$ echo $?
0
$ ./result/bin/gcc --version | head -1
gcc (GCC) 4.5.3

$ gcc t.c -R/foo
gcc: error: unrecognized option ‘-R’
$ echo $?
1
$ gcc --version | head -1
gcc (GCC) 4.6.2
--8<---------------cut here---------------end--------------->8---

(This is why the ‘build’ job at <http://hydra.nixos.org/eval/605870> has
been failing since the standard build environment switched from GCC 4.5
to 4.6 last month.)

In fact, the above should be applied to all GNU variants, so *gnu* may
be more appropriate than gnu-linux.

Thanks,
Ludo’.