master c601211 2/3: Unbreak dired-do-find-regexp in Emacs 26

[Dmitry Gutov]

branch: master
commit c601211e0d2f5174b5e748115a785d583235fe6e
Author: Dmitry Gutov <dgutov@yandex.ru>
Commit: Dmitry Gutov <dgutov@yandex.ru>

    Unbreak dired-do-find-regexp in Emacs 26
    
    * lisp/progmodes/xref.el (xref--show-xrefs):
    Support the old convention (bug#42967).
---
 lisp/progmodes/xref.el | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/lisp/progmodes/xref.el b/lisp/progmodes/xref.el
index 4da7b4e..264c750 100644
--- a/lisp/progmodes/xref.el
+++ b/lisp/progmodes/xref.el
@@ -963,6 +963,16 @@ Accepts the same arguments as `xref-show-xrefs-function'."
 
 (defun xref--show-xrefs (fetcher display-action)
   (xref--push-markers)
+  (unless (functionp fetcher)
+    ;; Old convention.
+    (let ((xrefs fetcher))
+      (setq fetcher
+            (lambda ()
+              (if (eq xrefs 'called-already)
+                  (user-error "Refresh is not supported")
+                (prog1
+                    xrefs
+                  (setq xrefs 'called-already)))))))
   (funcall xref-show-xrefs-function fetcher
            `((window . ,(selected-window))
              (display-action . ,display-action))))