"Something I implemented today: “is void”" by Herb Sutter
https://herbsutter.com/2022/09/25/something-i-implemented-today-is-void/
"As I presented at CppCon 2021 starting at 11:15, I’m proposing is (a
general type or value query) and as (a general cast, for only the safe
casts) for C++ evolution. The talk, and the ISO C++ evolution paper
P2392 it’s based on, explained why I hope that is and as can provide a
general mechanism to power pattern matching with inspect, while
conversely also liberating the power of pattern matching beyond just
inspect for use generally in the language (e.g., in requires clauses, in
general code)."
Lynn