Explore relationship between grammar::string_view_base and std::string_view #881
Description
Can someone derive from std::string_view as an alternative to deriving from boost::urls::grammar::string_view_base?
string_view_base stores a core::string_view and is a proxy for its member functions. In principle and semantically, it's guaranteed that string_view_base is OK to use as a base class while std::string_view or core::string_view are not. In practice, string_view_base has no virtual functions and doesn't have a virtual destructor.
The only class that refers to and derives from it is pct_string_view, making it inherit the usual member functions of a string_view.