>>>> grep-mode shows the number of matches on the mode-line.
>>>> Could xref do the same?
>>> Certainly.
>>>
>>> This should be especially useful later, when we make it update
>>> asynchronously.
>> Should I look into the implementation, or you already know how it could work?
>
> I might not get around to this until after the next few weeks, so you're
> welcome to take initiative.

Ok, here is the initial version based on grep/compilation variables: