Deletion of copy-ctor & copy-assignment - public, private or protected?

Question

In order to make an object non-copiable we can explicitly delete both its copy-constructor and copy-assignment operator.

My question is: What is the right place to

Answer 1

From Scott Meyers's book, Effective Modern C++ (Item 10), it seems that it is better to define them as public:

By convention, deleted functions are declared public, not private. There’s a reason for that. When client code tries to use a member function, C++ checks accessibility before deleted status. When client code tries to use a deleted private function, some compilers complain only about the function being private, even though the function’s accessibility doesn’t really affect whether it can be used. It’s worth bearing this in mind when revising legacy code to replace private-and-not-defined member functions with deleted ones, because making the new functions public will generally result in better error messages.

In addition, I believe that a deleted copy constructor/assignment, should be part of the class interface to be shared with ALL of the class users. Such kind of information should not be kept as secret by making them private.