bug#22947: 25.0.92; xref-find-definitions fails for Perl & etags

[Dmitry Gutov]

On 03/11/2016 09:05 PM, Bob Rogers wrote:

>    > The new etags builds the table without package qualifications, but
>    > after "emacs -Q" and "M-x visit-tags-table", "M-." still doesn't
>    > find either the parse_recipes or add_ingredient definitions.
>
>    Probably because you were not visiting a Perl file.  Because otherwise
>    it worked for me.

It works fine for me either way.

> Yes, I see that now.  But shouldn't it also work from other files?

One reason why it might not work, is if the same method name is not 
recognized by the other file's syntax table as the symbol at point. For 
etags, we're basically calling (thing-at-point 'symbol). You can 
evaluate this form in any context, and see if it returns the method name 
you were trying to look up.

If not, though, you can still press `C-u M-.' and type out the name of 
the method to look for (or even press M-n, see the default value 
inserted, and edit it), and press RET.

This is not too different from the find-tag workflow.

> I
> find it very useful to type M-. on a Perl method name that appears in
> documentation or in my notes, or to find a Perl definition mentioned in
> a Javascript file comment (and vice versa).

In general, it should work. Could you describe exactly what it is you 
tried (which file did you open, and where did you navigate before 
pressing `M-.'? did you press C-u?), so that we can reproduce it?

>    And many Perl programs have substantial C components.  Am I to
> understand that M-. between C and Elisp no longer works for Emacs?

You can just from C to Elisp just like before. From Elisp to C - a bit 
tricker, since emacs-lisp-mode sets up an xref backend using find-func 
by default, not etags. But you can

(add-hook 'emacs-lisp-mode-hook 'xref-etags-mode)

to make it use etags as well.