bug#43086: [PATCH] Allow tags backend to not query for TAGS file

[Eli Zaretskii <eliz@gnu.org>]

> Cc: 43086@debbugs.gnu.org
> Date: Sat, 7 Sep 2024 01:16:46 +0300
> From: Dmitry Gutov <dgutov@yandex.ru>
> 
> On 03/09/2024 19:39, Philip Kaludercic wrote:
> >>> I could imagine this might be extended to allow an auto-generate option,
> >>> but that feature seems out of scope of this patch, and probably would
> >>> require some interoperation with project.el.
> >> Indeed. Actually, I have an old, WIP patch for tag file
> >> auto-generation which, yes, uses project.el. I can post it again if
> >> you're curious.
> > Hasn't this issue been resolved by `etags-regen-mode'?
> 
> The part quoted above was, I think.
> 
> What might still be missing, is functioning better without having a tags 
> table generated - after all etags-regen-mode is off by default, and it 
> might not work for certain projects anyway.
> 
> Maybe just like this? This makes Xref identifier completion not query 
> for TAGS unless already loaded. In many cases that would be TRT, 
> although `C-u M-.` seems to regress (seems like we *would* want to query 
> eagerly there).

I don't understand why the obvious way of asking the user whether they
would like to generate the tags table is not the solution here.  What
did I miss?