20 Strings library [strings]

20.3 String classes [string.classes]

20.3.5 Hash support [basic.string.hash]

template<> struct hash<string>; template<> struct hash<u8string>; template<> struct hash<u16string>; template<> struct hash<u32string>; template<> struct hash<wstring>; template<> struct hash<pmr::string>; template<> struct hash<pmr::u8string>; template<> struct hash<pmr::u16string>; template<> struct hash<pmr::u32string>; template<> struct hash<pmr::wstring>;
If S is one of these string types, SV is the corresponding string view type, and s is an object of type S, then hash<S>()(s) == hash<SV>()(SV(s)).