bug#71370: 30.0.50; Please un-obsolete buffer-substring as a generalized variable

[Andrea Corallo]

Ihor Radchenko <yantar92@posteo.net> writes:

> Michael Heerdegen via "Bug reports for GNU Emacs, the Swiss army knife
> of text editors" <bug-gnu-emacs@gnu.org> writes:
>
>> Any arguments why this gv is different from the others that had been
>> deprecated?
>
> It is one of the commonly used gvs.
> https://github.com/search?q=%22%28setf+%28buffer-substring%22&type=code
> gives 500+ hits (and it is not all forks of one or two popular packages)

Interesting, I took the time to apply your methodology to all GV
obsoleted by the same commit and this is the result:

| GV                           | file occurrences |
|                              |        in github |
|------------------------------+------------------|
| buffer-file-name             |                5 |
| buffer-modified-p            |                7 |
| buffer-name                  |               48 |
| buffer-string                |              142 |
| buffer-substring             |              512 |
| current-buffer               |              234 |
| current-column               |                3 |
| current-global-map           |                0 |
| current-input-mode           |                0 |
| current-local-map            |                0 |
| current-window-configuration |                0 |
| default-file-modes           |                0 |
| current-window-configuration |                0 |
| default-file-modes           |                0 |
| documentation-property       |                8 |
| frame-height                 |               38 |
| frame-visible-p              |                0 |
| global-key-binding           |                3 |
| local-key-binding            |                0 |
| mark                         |                4 |
| mark-marker                  |                0 |
| marker-position              |               16 |
| mouse-position               |                7 |
| point                        |               32 |
| point-marker                 |                0 |
| point-max                    |                0 |
| point-min                    |               40 |
| read-mouse-position          |                0 |
| screen-height                |                4 |
| screen-width                 |               15 |
| selected-window              |                4 |
| selected-screen              |                0 |
| selected-frame               |                0 |
| standard-case-table          |                0 |
| syntax-table                 |                0 |
| visited-file-modtime         |                0 |
| window-height                |               13 |
| window-width                 |                9 |
| x-get-secondary-selection    |                0 |

While some of them are rarely/not used some others looks quite popular.
This is an indication that the popular ones are probably a good
abstraction or they are just convenient.

I don't know what would be the risk of un-obsoleting the popular ones
now, but if is not possible I think we should consider doing it for the
next release cycle.

  Andrea