x11-proto/xf86vidmodeproto is needed in order to compile nvidia-drivers. Reproducible: Always Steps to Reproduce: 1. emerge xorg from binary packages, doesn't pull in x11-proto/* 2. try to emerge nvidia-drivers from source 3. Works after manually installing x11-proto/xf86vidmodeproto
It would have been good to include the exact compile error and be specific about which version of the driver you used.
Hmm, sorry, couldn't reproduce it. Guess it's invalid.