Having someone who wrote the compiler to answer the question is very lucky, especially when port the code to new version.
He does come on HN and posts in comments quite often when D is brought up so it wouldn't be too unlikely to see, also he's coded his own games as well.
WalterBright is unusually active in pretty much all D-related communities I've visited. I've had him answer my nooby questions on IRC on multiple occasions.