It would actually be pretty interesting to see how you use Bison and Flex with utf-8.
Most resources say to not bother due to lack of support for Unicode, but they're so ubiquitous
Do they need special support for UTF-8? One of the nice things about UTF-8 is that you can treat it as an 8-bit encoding in many cases if you only care about substrings and don't need to decode individual non-ASCII characters.