Turn expiry on for nnselect groups

Articles in (persistent) groups from the gnus/nnselect backend will
now be run through the expiry process upon exit, like other persistent
groups. Expiry is not on by default for ephemeral nnselect groups but
may be turned on with nnselect-allow-ephemeral-expiry set to t.

* lisp/gnus/nnselect.el (nnselect-request-expire-articles): Make
article expiry work.
(nnselect-allow-ephemeral-expiry): New variable.
* doc/misc/gnus.texi (Creating Search Groups): Document
nnselect-allow-ephemeral-expiry.

2 files changed, 32 insertions, 18 deletions

diff --git a/doc/misc/gnus.texi b/doc/misc/gnus.texi
index a3def495c44..20a2d920841 100644
--- a/doc/misc/gnus.texi
+++ b/doc/misc/gnus.texi
@@ -21735,6 +21735,12 @@ articles are drawn.  If you want to create a @emph{persistent} group
 that sticks around after exit from the summary buffer, you can call
 @code{gnus-group-make-search-group} (bound to @kbd{G g}).
 
+Unlike persistent groups, ephemeral groups by default do not run
+articles through the expiry process on exiting. If you want expiry to
+happen in ephemeral search groups you can customize the variable
+@code{nnselect-allow-ephemeral-expiry}. In all cases the expiry
+process uses the underlying group's expiry parameters.
+
 So you just performed a search whose results are so fabulous you
 wished you had done a persistent search rather than an ephemeral one?
 No problem; you can create such a group by calling
diff --git a/lisp/gnus/nnselect.el b/lisp/gnus/nnselect.el
index b9072d4cb39..9193b38e315 100644
--- a/lisp/gnus/nnselect.el
+++ b/lisp/gnus/nnselect.el
@@ -256,6 +256,12 @@ as `(keyfunc member)' and the corresponding element is just
 (define-obsolete-variable-alias 'nnir-retrieve-headers-override-function
   'nnselect-retrieve-headers-override-function "28.1")
 
+(defcustom nnselect-allow-ephemeral-expiry nil
+  "If non-nil, articles in an ephemeral nnselect group will be put
+through the expiry process."
+  :version "29.1"
+  :type 'boolean)
+
 (defcustom nnselect-retrieve-headers-override-function nil
   "A function that retrieves article headers for ARTICLES from GROUP.
 The retrieved headers should populate the `nntp-server-buffer'.
@@ -457,24 +463,26 @@ If this variable is nil, or if the provided function returns nil,
                         :test #'equal :count 1)))))
 
 (deffoo nnselect-request-expire-articles
-    (articles _group &optional _server force)
-  (if force
-      (let (not-expired)
-        (pcase-dolist (`(,artgroup . ,artids) (ids-by-group articles))
-          (let ((artlist (sort (mapcar #'cdr artids) #'<)))
-            (unless (gnus-check-backend-function 'request-expire-articles
-                                                 artgroup)
-              (error "Group %s does not support article expiration" artgroup))
-            (unless (gnus-check-server (gnus-find-method-for-group artgroup))
-              (error "Couldn't open server for group %s" artgroup))
-            (push (mapcar (lambda (art)
-                            (car (rassq art artids)))
-                          (let ((nnimap-expunge 'immediately))
-                            (gnus-request-expire-articles
-                             artlist artgroup force)))
-                  not-expired)))
-        (sort (delq nil not-expired) #'<))
-    articles))
+    (articles group &optional _server force)
+  (let ((nnimap-expunge 'immediately) not-deleted)
+    (if (and (not force)
+             (not nnselect-allow-ephemeral-expiry)
+             (gnus-ephemeral-group-p (nnselect-add-prefix group)))
+        articles
+      (pcase-dolist (`(,artgroup . ,artids) (ids-by-group articles))
+        (let ((artlist (sort (mapcar #'cdr artids) #'<)))
+          (unless
+              (gnus-check-backend-function 'request-expire-articles artgroup)
+            (error "Group %s does not support article expiration" artgroup))
+          (unless (gnus-check-server (gnus-find-method-for-group artgroup))
+            (error "Couldn't open server for group %s" artgroup))
+          (setq not-deleted
+                (append
+                 (mapcar (lambda (art) (car (rassq art artids)))
+                         (gnus-request-expire-articles artlist artgroup
+                                                       force))
+                 not-deleted))))
+      (sort (delq nil not-deleted) #'<))))
 
 
 (deffoo nnselect-warp-to-article ()