bug#73484: 31.0.50; Abolishing etags-regen-file-extensions

[Eli Zaretskii <eliz@gnu.org>]

> Date: Tue, 1 Oct 2024 02:19:17 +0300
> Cc: spwhitton@spwhitton.name, 73484@debbugs.gnu.org
> From: Dmitry Gutov <dmitry@gutov.dev>
> 
> On 29/09/2024 11:25, Eli Zaretskii wrote:
> > I understand that we need to disable the Fortran and C fallbacks to
> > avoid false positives, but what do we want to do if the fallbacks are
> > disabled and no suitable language parser is found using the file name?
> > Just skip the file and do nothing? emit a warning? something else?
> 
> Just do nothing.

Doing nothing means the file's name will not appear at all in TAGS.  I
don't think that's TRT, since every file submitted to etags should be
mentioned in TAGS for the benefit of tags-search and similar features.

So I currently tend to modify etags such that if no language was
detected by the file's name/extension, and this new no-fallbacks
option was specified, etags will behave as if given --language=none
(which also means that if any regexps were specified, they will be
processed correctly for such files).  If no regexps were specified or
none matched, this means only the file's name will appear in TAGS, and
that's all.

If the above is not a good plan for some reason, feel free to holler.