[avr-gcc-list] Problems with abstract classes / pure virtual functions:

[Thomas . Schulze]

Hi!
I got a somehow mysterious (hopefully not to silly) problem involving abstract classes.
Here a test:

class abstract_base
{
public:
virtual void testfunction(void)=0;
virtual ~abstract_base(){} *
};

class concrete_class : public abstract_base
{
public:
void testfunction(void){}
~concrete_class(){}
};

Now I do the following:

int main(void)
{
concrete_class testobject;
}

And the Compiler warns me about:

warning: alignment of 'concrete_class::_ZTV14concrete_class' is greater than maximum object file alignment. Using 1
warning: alignment of 'abstract_base::_ZTV13abstract_base' is greater than maximum object file alignment. Using 1

And the Linker finally generates an error:
....h:8: undefined reference to `__cxa_pure_virtual' ( which is actually the line marked by *)

If You have any clues, why that problem shows up, please give me a hint.
Thancs a lot
Thomas