bug#54025: 27.2; dired-do-find-regexp skips occurences

[Dmitry Gutov]

Hi!

On 16.02.2022 13:40, Петров Андрей wrote:
> 5. Go back to dired buffer and try searching for "aaa" again.
>
>    Now*xref*  does not contain 3.txt file although it has an occurence of
>    "aaa".
>      
>      /home/andrey/3/1.txt
>      1: aaa
>      /home/andrey/3/2.txt
>      1: aaa
>      
>    After saving 3.txt and repeating the search*xref*  buffers shows all 3
>    entries as expected.
>
> Please take a look into `xref-revert-buffer' (g) inside*xref*  buffer
> also. It seems that it shows only occurences of the first file.

The reason this happens is because xref-matches-in-files uses the 
contents of open buffers to verify the regexp matches, and to show the 
(possibly syntax-highlighted) text in matches. The fact that such 
buffers can be modified and unsaved is obviously a problem.

I suggest we simply add a check before doing a search, which will remind 
you to save any such buffers. It will need to be added to 
project-find-regexp as well, naturally. Something like the patch below.

What do you think?

diff --git a/lisp/dired-aux.el b/lisp/dired-aux.el
index 41c45b4e51..c3b1b620bb 100644
--- a/lisp/dired-aux.el
+++ b/lisp/dired-aux.el
@@ -3266,6 +3266,12 @@ dired-do-find-regexp
   (require 'xref)
   (defvar grep-find-ignored-files)
   (declare-function rgrep-find-ignored-directories "grep" (dir))
+  (save-some-buffers)
+  (or (not (memq t (mapcar (lambda (buf)
+                             (and (buffer-file-name buf)
+                                  (buffer-modified-p buf)))
+                           (buffer-list))))
+      (user-error "Modified buffers exist; aborting"))
   (let* ((marks (dired-get-marked-files nil nil nil nil t))
          (ignores (nconc (mapcar
                           #'file-name-as-directory