From d02b15f2f9bf9b83641eac4e169ba79ac5026df8 Mon Sep 17 00:00:00 2001
From: Alexander Adolf <alexander.adolf@condition-alpha.com>
Date: Fri, 9 Dec 2022 22:15:42 +0100
Subject: [PATCH] Fix bug#59314

* lisp/net/eudc-capf.el (eudc-capf-complete): set completion-styles
buffer locally to a more generous value, so that more candidates can
pass the filtering
(eudc-capf-message-expand-name): renamed to
eudc-capf--message-expand-name to mark it as an internal use function,
and improved the doc string
---
 lisp/net/eudc-capf.el | 48 ++++++++++++++++++++-----------------------
 1 file changed, 22 insertions(+), 26 deletions(-)

diff --git a/lisp/net/eudc-capf.el b/lisp/net/eudc-capf.el
index e2bbd5b28b..c655c14df6 100644
--- a/lisp/net/eudc-capf.el
+++ b/lisp/net/eudc-capf.el
@@ -101,34 +101,30 @@ eudc-capf-complete
 The return value is either nil when no match is found, or a
 completion table as required for functions listed in
 `completion-at-point-functions'."
-  (if (and (seq-some #'derived-mode-p eudc-capf-modes)
-           (let ((mail-abbrev-mode-regexp message-email-recipient-header-regexp))
-             (mail-abbrev-in-expansion-header-p)))
-      (eudc-capf-message-expand-name)))
+  (when (and (or eudc-server eudc-server-hotlist)
+             (seq-some #'derived-mode-p eudc-capf-modes)
+             (let ((mail-abbrev-mode-regexp message-email-recipient-header-regexp))
+               (mail-abbrev-in-expansion-header-p)))
+    (setq-local completion-styles '(substring partial-completion))
+    (eudc-capf--message-expand-name)))
 
 ;;;###autoload
-(defun eudc-capf-message-expand-name ()
-  "Email address completion function for `message-completion-alist'.
-
-When this function is added to `message-completion-alist',
-replacing any existing entry for `message-expand-name' there,
-with an appropriate regular expression such as for example
-`message-email-recipient-header-regexp', then EUDC will be
-queried for email addresses, and the results delivered to
-`completion-at-point'."
-  (if (or eudc-server eudc-server-hotlist)
-      (progn
-        (let* ((beg (save-excursion
-                      (re-search-backward "\\([:,]\\|^\\)[ \t]*")
-                      (match-end 0)))
-               (end (point))
-               (prefix (save-excursion (buffer-substring-no-properties beg end))))
-          (let ((result
-                 (eudc-query-with-words (split-string prefix "[ \t]+") t)))
-            (when result
-              (list beg end
-                    (completion-table-with-cache
-                     (lambda (_) result) t))))))))
+(defun eudc-capf--message-expand-name ()
+  "Helper for `eudc-capf-complete'.
+
+Computes a completion table as required for functions listed in
+`completion-at-point-functions'."
+  (let* ((beg (save-excursion
+                (re-search-backward "\\([:,]\\|^\\)[ \t]*")
+                (match-end 0)))
+         (end (point))
+         (prefix (save-excursion (buffer-substring-no-properties beg end))))
+    (let ((result
+           (eudc-query-with-words (split-string prefix "[ \t]+") t)))
+      (when result
+        (list beg end
+              (completion-table-with-cache
+               (lambda (_) result) t))))))
 
 (provide 'eudc-capf)
 ;;; eudc-capf.el ends here
-- 
2.38.1