A12-4-2 - Unofficial Autosar C++ Guidelines Reference

Rule A12-4-2 (advisory, implementation, automated)

If a public destructor of a class is non-virtual, then the class should be declared final.

Rationale

If a public destructor of a class is non-virtual (i.e. no virtual, override or final keyword), then the class is not supposed to be used as a base class in inheritance hierarchy.

Note that a destructor needs to be virtual in a base class in order to correctly destroy an instance of a derived class through a pointer to the base class.

Example

// $Id: A12-4-2.cpp 289436 2017-10-04 10:45:23Z michal.szczepankiewicz $
class A // Non-compliant - class A should not be used as a base class because
// its destructor is not virtual, but it is
// not declared final
{
public:
A() = default;
A(A const&) = default;
A(A&&) = default;
A& operator=(A const&) = default;
A& operator=(A&&) = default;
~A() = default; // Public non-virtual destructor
};
class B final // Compliant - class B can not be used as a base class, because
// it is declared final, and
it should not be derived
// because its destructor is
not virtual
{
public:
B() = default;
B(B const&) = default;
B(B&&) = default;
B& operator=(B const&) = default;
B& operator=(B&&) = default;
~B() = default; // Public non-virtual destructor
};
class C // Compliant - class C is not final, and its destructor is virtual. It
// can be used as a base class
{
public:
C() = default;
C(C const&) = default;
C(C&&) = default;
C& operator=(C const&) = default;
C& operator=(C&&) = default;

virtual ~C() = default; // Public virtual destructor
};
class AA : public A
{
};
// class BA : public B // Compilation error - can not derive from final base
// class B
//{
//};
class CA : public C
{
};
void Fn() noexcept
{
AA obj1;
CA obj2;
A& ref1 = obj1;
C& ref2 = obj2;

ref1.~A(); // Calls A::~A() only
ref2.~C(); // Calls both CA::~CA() and C::~C()

}

Unofficial Autosar C++ Guidelines Reference

Rationale

Example

See also