bug#28407: 26.0.50; xref should use imenu

[Visuwesh]

[ஞாயிறு மே 15, 2022] Visuwesh wrote:

> [திங்கள் செப்டம்பர் 11, 2017] Dmitry Gutov wrote:
>
>> On 9/10/17 7:23 PM, Tom Tromey wrote:
>>> It would be nice if imenu were a back end for xref.
>>> Then M-. could also use symbols found by imenu.
>>> A further wrinkle on this would be if xref, project, and imenu
>>> worked
>>> together, so that M-. would automatically know to look at imenu results
>>> for other buffers in the same project.
>>
>> Agreed. It could be a nice default for when no tags table is currently
>> visited.
>
> I tried to write a general imenu backend in attached file (extracted
> from my init.el) but I hit quite a few roadblocks,
>
>   1. I activate the imenu backend iff there are no tags table defined
>      for the buffer but this means that one cannot use the imenu
>      backend to jump to definitions for symbols that TAGS do not know
>      of currently.  I can think of two ways to solve this problem,
>
>      (a) Check if the symbol is in TAGS table.
>      (b) Modify the etags backend so that the user can say "I have no
>      TAGS table for this file/project/whatever."
>
>      (a) is definitely not clean, and (b) sounds feasible but similar
>      situation can also exist with other backends (like elisp).
>
>      I'm lost on how to solve this problem.
>
>   2. I have not defined all the methods and the completion-table does
>      not handle the nested case of the index alist.  AFAIU from `(elisp)
>      Programmed Completion', completion "ends" when `try-completion'
>      returns t but I seem to be mistaken.  I have to rewrite
>      completion-table to be like `imenu--completion-buffer' but I don't
>      know how to pull that off.
>
>   3. `imenu-xref--in-alist' is mostly a 1-1 copy of `imenu--in-alist'
>      with the only difference being my function returns all matches of
>      the symbol instead of just the first one.  This should be easy
>      enough to fix by adding an optional argument INCLUDE-ALL to
>      `imenu--in-alist'.
>
> I'm testing in python-mode with the following settings,
>
>     (setq imenu-name-lookup-function (lambda (symbol item) (string-prefix-p 
> symbol item))
>           python-imenu-format-parent-item-jump-label-function (lambda (_ 
> name) name))

I solved (2) by using an affixation function.  I did (3) as well, and
I'm attaching my work as a patch against imenu.el.

imenu-xref.patch
Description: Text Data