bug#55879: 29.0.50; Missing ALL argument in find-sibling-file

[Eli Zaretskii]

> Resent-From: Daniel Martín <mardani29@yahoo.es>
> Original-Sender: "Debbugs-submit" <debbugs-submit-bounces@debbugs.gnu.org>
> Resent-CC: bug-gnu-emacs@gnu.org
> Resent-Sender: help-debbugs@gnu.org
> Date: Thu, 09 Jun 2022 23:27:46 +0200
> From:  Daniel Martín via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> 
> C-h f find-sibling-file RET
> 
> The documentation says "By default, return only files that exist, but if
> ALL is non-nil, return all matches.", but there is no ALL argument you
> can pass to the command.
> 
> Also, the Info documentation could reference ff-find-related-file when
> it gives the example of going from the source file to the header file in
> C files.

I still think we should have extended ff-find-related-file instead of
introducing a completely new facility with an incompatible UI.