[kmiroslav]

Interesting, I didn't know about `delete`.

Come to think of it, the trick to make something private in order to "remove" it is one of these very few areas where C++ makes you pay for something you don't use, so I'm not surprised that there is now a special keyword (well, a repurposed keyword) to address that.

[Rusky]

A declared-private but unimplemented method shouldn't have any runtime cost. =delete is just a syntactic convenience.