UTF-8 in C++, followup

As a follow-up on the post “Wait What… (UTF-8 in gcc)”, it turns out that since P1949R7 “C++ Identifier Syntax using Unicode Standard Annex 31” the snipped I showed is not allowed anymore in C++, retroactively, since it is a

Defect Report against C++ 20 and earlier

Clang already refused the use of these characters since version 14. Gcc, since version 12, although it seems to complain only when -Wpedantic is used.