bug#46611: Variables grep-window-height grep-scroll-output unused since Emacs 22.1?

[Stefan Kangas <stefan@marxist.se>]

Severity: minor

The new variables `grep-window-height' and `grep-scroll-output' were
announced in NEWS.22:

    *** The new variables `grep-window-height' and `grep-scroll-output' override
    the corresponding compilation mode settings, for grep commands only.

But if I'm not missing something, they were never actually part of Emacs
22.1, due to this commit:

    commit ab55f76f9ca670e3f41e4cfabeb35426f6b24fb6
    Author: Stefan Monnier <monnier@iro.umontreal.ca>
    Date:   Thu Mar 11 22:56:19 2004 +0000

        (kill-grep): Move here from compile.el
        (grep-error, grep-hit-face, grep-error-face)
        (grep-mode-font-lock-keywords): New variables.
        (grep-regexp-alist): Simplify regexp and add `binary' case.
        (grep-mode): New mode.
        (grep-process-setup): Simplify.
    [...]
    -  (if grep-window-height
    -      (set (make-local-variable 'compilation-window-height)
    -      grep-window-height))
    -  (set (make-local-variable 'compile-auto-highlight)
    -       grep-auto-highlight)
    -  (set (make-local-variable 'compilation-scroll-output)
    -       grep-scroll-output)

Stefan, do you remember any of this?  Were they removed intentionally?

Should we re-add the above lines?  Or, given that no one seems to have
noticed their absence in 16 years, perhaps it is better to just declare
them obsolete?

Or better yet, maybe we should:

1) Declare `grep-window-height' obsolete (as I'm not sure how useful it
   is).

2) Keep `grep-scroll-output' (it seems more useful) but change it from a
   boolean, and set it to the symbol 'default', which is taken to mean
   to just use whatever value 'compilation-scroll-output is set to. That
   way, we don't break existing configuration and behavior, plus we also
   allow for configuring this specifically, as was probably originally
   intended.  (I don't necessarily see the use for configuring it
   separately for grep, but at least the existence of an option
   documents that the behavior can be changed and how.)

Any opinions or comments here?