[Bug c++/30340] New: pure virtual function called on const & declared with previous declaration without a definition, const & assigned by temporary

[mjtruog at fastmail dot ca]

I have an example that illustrates the problem since it is rather hard to
describe in an easy to understand way.  Notice how the alternative constructor
for C gives an unrelated compile time error (that may be a separate or related
problem).  This could be understood and accepted behavior but it really does
seem quite strange... please tell me if this is the way things should work (C++
standard does not endorse this behavior, does it?).

class A;

class C
{
    public:
        C(int i, A const &test) : m_test(test) { i = 0;}
        C(A const &test) : m_test(test) {}
        void a() const;
    private:
        A const & m_test;
};

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

void C::a() const { m_test.a(); }

class B : public A
{
    public:
        void a() const { int i = 1; i *= 1; }
};

int main()
{
    // using this constructor causes "error: request for member 'a' in 'c',
which is of non-class type 'C ()(B (*)())'"
    //C c(B());

    // this constructor allows the example to compile
    C c(1, B());
    c.a();
}


-- 
           Summary: pure virtual function called on const & declared with
                    previous declaration without a definition, const &
                    assigned by temporary
           Product: gcc
           Version: 4.1.1
            Status: UNCONFIRMED
          Severity: critical
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: mjtruog at fastmail dot ca


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30340