c++20 moves a lot of things to constexpr, why not boost::spirit?

[piotr5]

for now the workaround is to manually copy boost::spirit::unicode::detail::category_lookup() into a constexpr function if I wish to make use of the table, and then maybe reimplement the query.hpp file's inline functions (i.e. boost::spirit::ucd namespace of functions identifying what each character does do) as constexpr too. then I can at least get that tiny part of the functionality in boost::spirit to work at compiletime. any reason why utf shouldn't be parsed at compile-time too?

i.e. my proposal is to put constexpr in front of all inline functions in include/spirit/home/support/char_encoding/unicode/*.hpp
to make those tables more accessible at compile-time!
after that look through the basic functionality code of boodt::spirit and add constexpr everywhere in the headers' inline functions where the compile-option -Winvalid-constexpr remains silent. c++20 allows for using vectors and strings at compile-time now! so please do some compile-time parsing with those constexpr strings! but that's optional and an ongoing effort. I'd be happy if boost::spirit could at least tell me what kind of characters the programmers have put into their source-code's text-constants to at least do some Concepts...