auto first(auto... params) { return params...[0]; }
Unless I'm missing something - but the post is showing off the fact that you can index into the list of types of the parameters, as well as the parameters themselves (in which case you need full template syntax).
Also COP2 instructions were not allowed in branch delay slots (presumably for similar reasons), however some games (from memory Tekken3) do actually do this. I always wondered if it was a sneaky anti-emulation thing :) (because many emulators had issues with this, or needed special handling).