19 Diagnostics library [diagnostics]

19.6 Stacktrace [stacktrace]

19.6.4 Class template basic_­stacktrace [stacktrace.basic]

19.6.4.7 Hash support [stacktrace.basic.hash]

template<> struct hash<stacktrace_entry>; template<class Allocator> struct hash<basic_stacktrace<Allocator>>;
The specializations are enabled ([unord.hash]).