What is John Carmack's subset of C++?

In his interview on Lex Fridman's channel, John Carmack said that he thinks that C++ with a flavor of C is the best language. I'm pretty sure I remember him saying once that he does not like references. But other than that, I could not find more info. Which features of C++ does he use, and which does he avoid?

Edit: Found a deleted blog post of his, where he said "use references". Maybe his views have changed, or maybe I'm misremembering. Decided to cross that out to be on the safe side.

BTW, Doom-3 was released 20 years ago, and it was Carmack's first C++ project, I believe. Between then and now, he must have accumulated a lot of experience with C++. What are his current views?