xref-find-references returns duplicates

xref-find-references returns duplicates

[Petteri Hintsanen]

Hello list,

I discovered a somewhat peculiar case where xref-find-references returns 
duplicate references for elisp symbols.

Here is a toy example:

1. Create a file ~/foo/bar/bar.el with contents:

   (defun bar-f ())

   (defun bar-g ()
     (bar-f))

   (provide 'bar)

2. Create a git repo in ~/foo/bar and commit bar.el.  This is just to 
set up a project that Emacs can recognize.

3. Start emacs -Q and eval

   (add-to-list 'load-path "~/foo")
   (add-to-list 'load-path "~/foo/bar")
   (require 'bar)

4. Visit ~/foo/bar/bar.el and do xref-find-references for bar-f

On my machine I get

   bar.el
   1: (defun bar-f ())
   4:   (bar-f))
   1: (defun bar-f ())
   4:   (bar-f))

i.e. references are duplicated.  The issue seems to be in load-path: if 
I remove ~/foo from step (3) above, then I don't see any duplicates.

Am I abusing load-path somehow, or is this a bug, or something else?
Emacs version is 28.2, running on Debian.


(The real use case is elisp directory hierarchy like this

   ~/elisp/
   ~/elisp/package-a/
   ~/elisp/package-b/
   ~/elisp/package-c/
   ...

where package dirs are checkouts from various repositories, and all 
directories are added to load-path.  ~/elisp/ has miscellaneous files 
which do not belong to any package.  I guess I could work around this 
just by putting them to ~/elisp/etc/ or something, but I'd like to know 
why xref works here like it does.)



Thanks,
Petteri

Re: xref-find-references returns duplicates

[Dmitry Gutov]

On 19/12/2022 02:25, Petteri Hintsanen wrote:
> Hello list,
> 
> I discovered a somewhat peculiar case where xref-find-references returns 
> duplicate references for elisp symbols.
> 
> Here is a toy example:
> 
> 1. Create a file ~/foo/bar/bar.el with contents:
> 
>    (defun bar-f ())
> 
>    (defun bar-g ()
>      (bar-f))
> 
>    (provide 'bar)
> 
> 2. Create a git repo in ~/foo/bar and commit bar.el.  This is just to 
> set up a project that Emacs can recognize.
> 
> 3. Start emacs -Q and eval
> 
>    (add-to-list 'load-path "~/foo")
>    (add-to-list 'load-path "~/foo/bar")
>    (require 'bar)
> 
> 4. Visit ~/foo/bar/bar.el and do xref-find-references for bar-f
> 
> On my machine I get
> 
>    bar.el
>    1: (defun bar-f ())
>    4:   (bar-f))
>    1: (defun bar-f ())
>    4:   (bar-f))
> 
> i.e. references are duplicated.  The issue seems to be in load-path: if 
> I remove ~/foo from step (3) above, then I don't see any duplicates.
> 
> Am I abusing load-path somehow, or is this a bug, or something else?

I suppose it's a bug, or a limitation of the algorithm anyway.

The default "find references" implementation currently delegates to 
xref-references-in-directory, which uses the semantic-symref-tool 
facility to search for a simple notion of "references" inside a 
directory tree. It doesn't have a mechanism to exclude certain 
directories, such as the current project root (from being searched twice 
over).

You can file a bug report with 'M-x report-emacs-bug', different ways to 
solve this exist, more or less adequately.

Re: xref-find-references returns duplicates

[Petteri Hintsanen]

Dmitry Gutov <dgutov@yandex.ru> writes:

> I suppose it's a bug, or a limitation of the algorithm anyway.

Ok, thanks for explanation.  As a workaround, I moved files from the
parent directory into their own subdirectory, and added that to
load-path instead of the parent dir.  I can easily live with this.

> You can file a bug report with 'M-x report-emacs-bug', different ways
> to solve this exist, more or less adequately.

Very well, I'll file a bug soon-ish.

Thanks,
Petteri