In file included from /usr/include/xorg/xf86DDC.h:15:0, from /usr/include/xorg/vgaHW.h:24, from /usr/src/RPM/BUILD/VirtualBox-5.2.8_OSE/src/VBox/Additions/x11/vboxvideo/vboxvideo.c:64: /usr/include/xorg/edid.h:618:6: warning: ISO C99 doesn't support unnamed structs/unions [-Wpedantic] }; Там действительно unnamed union.