Rewrite gnus-search-query-expand-key

* lisp/gnus/gnus-search.el (gnus-search-query-expand-key): There was a
misunderstanding about how completion-all-completion works (if the
test string can't be completed, the whole table is returned). Simplify
to use try-completion.
* test/lisp/gnus/gnus-search-tests.el (gnus-s-expand-keyword): Ensure
that an unknown/uncompletable keyword is returned unmolested.

2 files changed, 13 insertions, 13 deletions

diff --git a/lisp/gnus/gnus-search.el b/lisp/gnus/gnus-search.el
index 898b57bcef8..56675eb8651 100644
--- a/lisp/gnus/gnus-search.el
+++ b/lisp/gnus/gnus-search.el
@@ -629,18 +629,16 @@ gnus-*-mark marks, and return an appropriate string."
     mark))
 
 (defun gnus-search-query-expand-key (key)
-  (cond ((test-completion key gnus-search-expandable-keys)
-         ;; We're done!
-         key)
-        ;; There is more than one possible completion.
-        ((consp (cdr (completion-all-completions
-                      key gnus-search-expandable-keys #'stringp 0)))
-         (signal 'gnus-search-parse-error
-                 (list (format "Ambiguous keyword: %s" key))))
-        ;; Return KEY, either completed or untouched.
-        ((car-safe (completion-try-completion
-                    key gnus-search-expandable-keys
-                    #'stringp 0)))))
+  (let ((comp (try-completion key gnus-search-expandable-keys)))
+    (if (or (eql comp 't)               ; Already a key.
+            (null comp))                ; An unknown key.
+        key
+      (if (string= comp key)
+          ;; KEY matches multiple possible keys.
+          (signal 'gnus-search-parse-error
+                  (list (format "Ambiguous keyword: %s" key)))
+        ;; We completed to a unique known key.
+        comp))))
 
 (defun gnus-search-query-return-string (&optional delimited trim)
   "Return a string from the current buffer.
diff --git a/test/lisp/gnus/gnus-search-tests.el b/test/lisp/gnus/gnus-search-tests.el
index e30ed9a80a7..6148da65621 100644
--- a/test/lisp/gnus/gnus-search-tests.el
+++ b/test/lisp/gnus/gnus-search-tests.el
@@ -49,7 +49,9 @@
          (default-value 'gnus-search-expandable-keys))
         (pairs
          '(("su" . "subject")
-           ("sin" . "since"))))
+           ("sin" . "since")
+           ("body" . "body")
+           ("list-id" . "list-id"))))
     (dolist (p pairs)
       (should (equal (gnus-search-query-expand-key (car p))
                      (cdr p))))