collect2 / ld giving strange errors with undefined virtual functions

[Martin v. Loewis]

> But you could get a better warning to the user with less effort: all
> the linker needs to know is that a particular name is that of a
> virtual table.
[...]
> [Hint: try checking whether the first non-inlined, non-pure virtual
> function of class A is defined]

I'd argue that it is better to be explicitly told what the first
non-inlined non-pure virtual function is, instead of figuring out
yourself. Whenever I got that CC message, it took me quite a while to
detect what I forgot to implement.

Regards,
Martin