bug#67687: Feature request: automatic tags management

[Eli Zaretskii]

> Date: Sun, 31 Dec 2023 17:25:35 +0200
> Cc: eskinjp@gmail.com, 67687@debbugs.gnu.org, michael.albinus@gmx.de
> From: Dmitry Gutov <dmitry@gutov.dev>
> 
> On 31/12/2023 08:34, Eli Zaretskii wrote:
> >> +Note that this feature disables itself if you have already manually
> >> +visited a tags table (with @kbd{M-x visit-tags-table}, or through an
> >> +explicit prompt triggered by some feature that requires tags).
> > This aspect is IMO somewhat problematic.  I wasn't aware of it, and
> > now that I read this, I'm not sure it is correct and will meet user
> > expectations.
> 
> I'm pretty sure you asked for it: that even when this mode is on, it 
> shouldn't interfere with completion tables explicitly visited by the user.

"Interfere" and "prevent automatic regeneration" is not the same.

I think this probably warrants a separate defcustom: some people might
want such regeneration, even if the tags table was loaded manually,
others won't.  And I think the default should be to regenerate them
regardless.

> And either way it seems like a prerequisite for enabling 
> etags-regen-mode by default sometimes in the future.

How so?  The fact that I loaded TAGS doesn't necessarily mean I don't
want it updated when the sources change.  Or what am I missing?