http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59648
--- Comment #4 from Markus Trippelsdorf <trippels at gcc dot gnu.org> --- Xext/panoramiX.c sets: int PanoramiXNumScreens = 0; and events.i has: extern __attribute__((visibility("default"))) int PanoramiXNumScreens; ... typedef struct { int screens[16]; int numScreens; } ScreenInfo; ScreenInfo screenInfo; int fn1() { if (noPanoramiXExtension) { int i; i = PanoramiXNumScreens - 1; while (i--) CheckVirtualMotion_x = (long)screenInfo.screens[i]; } return 0; } Which is clearly invalid. Setting PanoramiXNumScreens = 1 in Xext/panoramiX.c fixes the issue.