[Bug libstdc++/109947] std::expected monadic operations do not support move-only error types yet

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109947

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
To be clear, a move-only value type is OK. A move-only error type is not.