I see here that the C standard library now has typedefs of std::basic_string like u8string and u16string, but I don't see any member functions or algorithms that know much of anything about Unicode.

Let's say I want to iterate over the "grapheme clusters" in a string stored as UTF-8. These are the things that humans view as "characters", even though they may be multiple bytes or even multiple 32bit code units (like emoji flags