https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96088
--- Comment #3 from Marc Glisse <glisse at gcc dot gnu.org> --- (In reply to Jonathan Wakely from comment #2) > Or use unordered_map<string, int, hash<string_view>, equal_to<>> which > should perform better. Good idea. > We haven't implemented http://wg21.link/p0919r3 and http://wg21.link/p1690r1 > yet, I wonder if those would help, especially if we make the internal > helpers available pre-C++20. That could allow the range insertion to use the > heteregenous lookup, to avoid creating temporaries. I'm not sure if that > would be conforming though. Heterogeneous lookup is observably different, > and not conforming in C++17. Restricting it to a few standard types like string should not be observable. > Adding hash<string>::operator()(string_view) is an interesting idea for the > standard though. Indeed. If we want to, I think it is possible to add some overloads for when the argument is exactly const char* or string_view, which should remain conforming and provide a significant part of the benefits.
