Gentoo's Bugzilla –
Attachment 351876 Details for
Bug 474686x11-apps/xdm with sys-devel/gcc-4.8 when dev-libs/libbsd is present - .../work/xdm-1.1.11/xdm/genauth.c:350:5: error: implicit declaration of function ‘arc4random’ [-Werror=implicit-function-declaration]