Is it enough to delete operator=(Type type)?

Question

Is the following enough (from a best-practice perspective) for a nonmovable type?

class A
{
   A(const A&) = delete;
   A(A&&) = delete;
   A& operator=(A) = delete;
public:
   A();
};

Or do I have to delete the copy/move assignment operators separately? Also is a destructor required here?

Answer 1

Yes, declaring the copy constructor and copy assignment operators as deleted is enough. Since you are declaring a copy constructor and copy assignment operator the move constructor and move assignment operator will not be automatically generated. You do not need to explicitly declare them deleted.

From §12.8/9 (Emphasis added)

If the definition of a class X does not explicitly declare a move constructor, one will be implicitly declared as defaulted if and only if
— X does not have a user-declared copy constructor,
— X does not have a user-declared copy assignment operator,
— X does not have a user-declared move assignment operator,
— X does not have a user-declared destructor, and
— the move constructor would not be implicitly defined as deleted.

From §12.8/20 (Emphasis added)

If the definition of a class X does not explicitly declare a move assignment operator, one will be implicitly declared as defaulted if and only if
— X does not have a user-declared copy constructor,
— X does not have a user-declared move constructor,
— X does not have a user-declared copy assignment operator,
— X does not have a user-declared destructor, and
— the move assignment operator would not be implicitly defined as deleted.