Stateful compile-time functions

In section 9.1.2 of this book[1] it mentions that C++23 allows for stateful constexpr functions, and even shows an example. I can't seem to get it to compile on godbolt. Is the book completely wrong about something so fundamental, or am I doing something wrong?

[1] https://simplifycpp.org/books/cpp/Mastering_Modern_C++23_A_Complete_Guide_to_the_Latest_Standard.pdf

Edit: Godbolt link with code from that section -> https://godbolt.org/z/94j9EK87b

https://redd.it/1wn70fq
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