[Bug c++/107022] error: use of deleted function 'std::unordered_map

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107022

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Yes, and the standard says that instantiating std::unordered_map with
incomplete types is undefined.