Rule A5-10-1 (required, implementation, automated)
A pointer to member virtual function shall only be tested for equality with null-pointer-constant.
Rationale
The result of equality comparison between pointer to member virtual function and anything other than null-pointer-constant (i.e. nullptr, see: A4-10-1) is unspecified.
Example
// $Id: A5-10-1.cpp 289436 2017-10-04 10:45:23Z michal.szczepankiewicz $
class A
{
public:
virtual ~A() = default;
void F1() noexcept {}
void F2() noexcept {}
virtual void F3() noexcept {}
};
void Fn()
{
bool b1 = (&A::F1 == &A::F2);
// Compliant
bool b2 = (&A::F1 == nullptr); // Compliant
bool b3 = (&A::F3 == nullptr); // Compliant
bool b4 = (&A::F3 != nullptr); // Compliant
bool b5 = (&A::F3 == &A::F1);
// Non-compliant
}
See also
HIC++ v4.0 [9]: 5.7.2 Ensure that a pointer to member that is a virtual function is only compared (==) with nullptr.
JSF December 2005 [8]: AV Rule 97.1 Neither operand of an equality operator (== or !=) shall be a pointer to a virtual member function.