Comment 27 for bug 1047306

we've bisected a bug in i915_dri.so which was caused by this commit:

commit c8a86f717f8e30204c615d06bcec159410ac06c5
Author: Brian Paul <email address hidden>
Date: Fri Aug 31 08:33:31 2012 -0600

    mesa: move IS_NEGATIVE() and DIFFERENT_SIGNS() to macros.h

and it was discussed briefly on #intel-gfx:

< ickle> let me guess: GLboolean is a char
< ickle> yup.
< ickle> DIFFERENT_SIGNS() always return 0 as (unsigned char)(1<<31) == 0
< ickle> also note that fi_type isn't well defined when sizeof(int)!=4

the downstream bug is

https://bugs.launchpad.net/ubuntu/quantal/+source/mesa/+bug/1047306

causing unity/compiz segfaults with hw using the dri driver. Reverting just that commit was verified to work.