Pure virtual destructor in C++

Question

Is it wrong to write:

class A {
public:
    virtual ~A() = 0;
};

for an abstract base class?

At least that compiles in MSVC... Will

Answer 1

Private destructors: they will give you an error when you create an object of a derived class -- not otherwise. A diagnostic may appear though.

12.4 Destructors

6 A destructor can be declared virtual (10.3) or pure virtual (10.4); if any objects of that class or any derived class are created in the program, the destructor shall be defined.

A class with a pure virtual destructor is an abstract class. Note well:

10.4 Abstract classes

2 A pure virtual function need be defined only if called with, or as if with (12.4), the qualified-id syntax (5.1).

[Note:a function declaration cannot provide both a pure-specifier and a definition —end note ]

Taken straight from the draft:

struct C {
   virtual void f() = 0 { }; // ill-formed
};