bug#49261: 28.0.50; File Locking Breaks Presumptuous Toolchains

[Eli Zaretskii <eliz@gnu.org>]

> From: Michael Albinus <michael.albinus@gmx.de>
> Cc: larsi@gnus.org,  ncaprisunfan@gmail.com,  49261@debbugs.gnu.org
> Date: Fri, 09 Jul 2021 10:28:29 +0200
> 
> > What other degrees besides "all" and "nothing" would you like to have?
> > And why?
> 
> Remote files (all files which match tramp-file-name-regexp). For
> backward compatibility, and possibly due to performance reasons.
> 
> Mounted files (all files which match `mounted-file-systems'). Possibly
> due to performance reasons.

You want a capability to exempt different kinds of files from locking?
Why would that be a good idea?  Performance doesn't cut it, IMO,
because if one wants to be protected from clobbering, one doesn't care
about performance.  And if one cares about performance for those
special kinds of files, it most probably means one doesn't care about
file locking at all.

So I submit that a binary switch is good enough.

> These are just examples. One could imagine more fine-grained choices
> (for example, only files located on a given host), or completely other
> selections.

I suggest not to imagine potential features.  We already have too many
features, so we should only add new ones if they are really required.
just because someone could use a finer-grained setting doesn't yet
mean we need to cater to that in core.

In any case, now that make-lock-file-name is exposed to Lisp, they can
override or advise it to do whatever they like, right?