Question

Is there any way to prevent deleting a pointer in C++ by its declaration?

I’ve tried following code without luck.

const int* const foo()
{
    static int a;
    return &a;
}

int main()
{
    const int* const a = foo();

    *a = 1;   //compiler error, const int*
    a++;      //compiler error, int* const
    delete a; //no compiler error, I want to have compiler error here

    return 0;
}

Answer 1

You cannot declare a pointer to an arbitrary type in a way which prevents calling delete on the pointer. Deleting a pointer to const (T const*) explains why that is.

If it was a pointer to a custom class you could make the delete operator private:

class C {
    void operator delete( void * ) {}
};

int main() {
    C *c;
    delete c; // Compile error here - C::operator delete is private!
}

You certainly shouldn’t make the destructor private (as suggested by others) since it would avoid creating objects on the stack, too:

class C {
    ~C() {}
};

int main() {
    C c; // Compile error here - C::~C is private!
}