“Mapping from source file (other than a UTF-8 source file)(since C++23) characters to the basic character set(until C++23)translation character set(since C++23) during translation phase 1 is implementation-defined, so an implementation is required to document how the basic source characters are represented in source files.”*
“Mapping from source file (other than a UTF-8 source file)(since C++23) characters to the basic character set(until C++23)translation character set(since C++23) during translation phase 1 is implementation-defined, so an implementation is required to document how the basic source characters are represented in source files.”*
⇒ pre C++23, you could have a C++ compiler that used an Unicode “Pile of poo” (https://www.unicode.org/L2/L2017/17407-frowning-poo.pdf) instead of the letter F.