[nomenclature] What is a bug?

[Lutger]

Justin Johansson wrote:

> Perhaps this topic could be posted as
> "[challenge] Define just exactly what a bug is".
> 
> I trust this topic will yield some interesting conversation.
> 
> Cheers
> Justin Johansson

Behavior that is not according to spec.

The problem with that is that the spec may be unclear or not even exist. If 
in that case, some behavior is unwanted, I would call it a bug in the spec 
or requirements.

Note that bugs may actually be wanted behavior. One such case is uniform 
function call syntax on arrays, which started life as a compiler bug. 
Afterwards, the spec was changed and thus the bug was solved.