bug#53749: 29.0.50; [PATCH] Xref backend for TeX buffers

[David Fussner]

Hi Arash,

Thanks for the nudge. I am in fact in the final stages of preparing a
new patch to get xref working in TeX buffers. As usual, the main
complexities are in xref-find-references, and while I have you here I
wonder whether I could ask your thoughts about addressing one part of
this complexity.

The semantic/symref backend used by xref-find-references greps in
files matching the major-mode of the buffer where the user calls the
command. It looks in semantic-symref-filepattern-alist for
file-extensions matching the major-mode, and if that fails it looks in
auto-mode-alist. When both fail to produce any file extensions it
tells the user to customize semantic-symref-filepattern-alist. Also,
if it finds things in s-s-f-a, it doesn't go on to auto-mode-alist, so
s-s-f-a has to be complete in order to be useful. In effect, we need
s-s-f-a to hold all the extensions for all the modes that can appear
as values of major-mode, and I notice that AUCTeX has started to
populate that alist, though incompletely. I'm also aware that many
packages add their own extensions to files which are basically TeX or
LaTeX files, and I wonder whether we can really keep up with the whole
of CTAN in terms of providing complete lists of extensions for
s-s-f-a.

As an example of where we are, if you open a plain-tex-mode (or
plain-TeX-mode) file and M-? with point on some standard word you'll
currently get the message to customize s-s-f-a, because
auto-mode-alist has only tex-mode and s-s-f-a doesn't cover them,
either.

I ask you Arash, therefore, as an AUCTeX and emacs developer, and I
ask any other developers also, whether you'd prefer me just to put
together as complete a list as possible for addition to s-s-f-a --
with patches for AUCTeX for all the new modes there -- or, and this is
what I'm finishing up now, whether you'd consider it overkill to have
code that constructs (or modifies) entries in s-s-f-a by searching in
auto-mode-alist and in the buffer-list for all the file extensions
emacs knows about that relate to the current major-mode. Changes in
s-s-f-a wouldn't be persistent across sessions, but they would allow a
user to open a file with any file extension, run latex-mode, and M-?
would work in that buffer, and search that buffer from another buffer
with a related major-mode, all without needing any user intervention.
It would also allow customizations in auto-mode-alist to appear in
s-s-f-a automatically, which seems convenient to me.

If your answer is "show me the code", I'll do that shortly, but I
wondered whether anyone had any preliminary thoughts on the matter.

Best, and sorry for the long question,

David.

On Mon, 22 Apr 2024 at 14:06, Arash Esbati <arash@gnu.org> wrote:
>
> David Fussner <dfussner@googlemail.com> writes:
>
> > Thanks for the clarifications. If you look at the current patch to
> > tex-mode.el, there's one function call added to TeX-mode-hook, mainly
> > for my own testing purposes, but no matter what the final patch looks
> > like it should only similarly require a single function call in an
> > AUCTeX hook to activate the new xref code there, along with one in
> > tex-common-initialization for the in-tree modes. If and when all
> > parties are satisfied by the patch I'll certainly be in touch with you
> > to find out how you'd prefer to handle activating it (or not) in
> > AUCTeX. The current state of affairs is a convenience for me and for
> > anyone else who cares to test the code.
>
> Hi David,
>
> I justed wanted to come back on this report and ask if there is any
> progress?  It would be nice to get Xref working within TeX buffers.
>
> TIA.  Best, Arash