no_case is a type in some make_primitives specializations, and a bool in others. #748
Description
make_primitives<...>::no_case is a type in some make_primitives specializations, and a bool in others. This seems inconsistent, and I wonder if this is a bug:
boost/spirit/home/qi/string/lit.hpp:263:77: boost::spirit::qi::make_primitive::no_case is a type
boost/spirit/home/qi/char/char_class.hpp:98:27: boost::spirit::qi::make_primitive::no_case is a value
boost/spirit/home/qi/string/symbols.hpp:395:77: boost::spirit::qi::make_primitive::no_case is a type
The reason I'm asking is that I wrote a proposal P2669 to disallow such differences. When I presented it at the C++ standardization meeting some were worried that a lot of code would break, and that those breakages would not be bugs. To check the situation I made a Clang plugin which detects such differences. I then compiled quite a few repos (using vcpkg) and in Boost I encountered this only case where code would break if P2669 was standardized.
So I would be very interested in if this is indeed a bug or if you have good usage for the different kinds of the no_code name in different specializations. In the latter case it would be very interesting to get a statement regarding the complexities involved in fixing this if P2669 was standardized.