Support "reverting" Xref buffers (bug#35702)

* lisp/progmodes/xref.el (xref--fetcher): New variable.
(xref--xref-buffer-mode-map): Add binding for 'g'.
(xref--revert-xref-buffer): New command.
(xref--show-xref-buffer): Accept a function as the first argument.
(xref--show-xrefs): Same.
(xref--find-xrefs): Pass the above a fetcher function.

* lisp/progmodes/project.el (project-find-regexp)
(project-or-external-find-regexp): Same.

* lisp/dired-aux.el (dired-do-find-regexp): Same.

1 files changed, 7 insertions, 3 deletions

diff --git a/lisp/progmodes/project.el b/lisp/progmodes/project.el
index e44cee2133f..d494efa493a 100644
--- a/lisp/progmodes/project.el
+++ b/lisp/progmodes/project.el
@@ -351,7 +351,9 @@ requires quoting, e.g. `\\[quoted-insert]<space>'."
               (project--files-in-directory dir
                                            nil
                                            (grep-read-files regexp))))))
-    (project--find-regexp-in-files regexp files)))
+    (xref--show-xrefs
+     (apply-partially #'project--find-regexp-in-files regexp files)
+     nil)))
 
 (defun project--dir-ignores (project dir)
   (let* ((roots (project-roots project))
@@ -376,7 +378,9 @@ pattern to search for."
           (project-files pr (append
                              (project-roots pr)
                              (project-external-roots pr)))))
-    (project--find-regexp-in-files regexp files)))
+    (xref--show-xrefs
+     (apply-partially #'project--find-regexp-in-files regexp files)
+     nil)))
 
 (defun project--find-regexp-in-files (regexp files)
   (pcase-let*
@@ -418,7 +422,7 @@ pattern to search for."
     (setq xrefs (xref--convert-hits (nreverse hits) regexp))
     (unless xrefs
       (user-error "No matches for: %s" regexp))
-    (xref--show-xrefs xrefs nil)))
+    xrefs))
 
 (defun project--process-file-region (start end program
                                      &optional buffer display