[einpoklum]

Sorry to be the nitpicker here, but - the best incremental improvement would probably have seen move-destruction instead of just moves, which keep the source object alive and force the allowance for a valid 'empty' or 'dummy' state.

See also:

* https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2002/n13... move designs

* https://www.foonathan.net/2017/09/destructive-move/