bug#30397: Random numbers in grep mode-line

[Juri Linkov]

>> What was the goal of this feature and where it is documented?
>
> `(emacs) Compilation' (and similar in etc/NEWS):
>
>       While compilation proceeds, the mode line is updated to show the
>     number of errors, warnings, and informational messages that have been
>     seen so far.
>
> Perhaps it needs some adjustment for grep.
>
> Original report: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=25354

Yes, some adjustment is needed for grep.  That reminded me
about two unclosed feature requests: bug#13417 and bug#14017
that proposed to display these numbers also at the bottom of
output buffers.  But the showstopper was to decide on the
final format of such messages.  Although this looks good:

  Grep finished with 42 matches in 5 lines at Thu Jul 21 15:02:15

Than the mode-line will display two numbers: the number of matches
and the number of matching lines (in green).