Add tramp-cleanup-bufferless-connections (bug#76417)

* doc/misc/tramp.texi (Cleanup remote connections): Add
'tramp-cleanup-bufferless-connections'.

* etc/NEWS: Announce 'tramp-cleanup-bufferless-connections'.

* lisp/net/tramp-cmds.el:
(tramp-list-remote-buffer-connections): New function.
(tramp-cleanup-bufferless-connections): New command.
(tramp-list-remote-buffers): Account for 'buffer-file-name'.

doc/misc/tramp.texi

@@ -4783,13 +4783,13 @@ proxy definitions (@pxref{Ad-hoc multi-hops}).
 
 @deffn Command tramp-cleanup-all-buffers
 Just as for @code{tramp-cleanup-all-connections}, all remote
-connections and ad-hoc proxy definition are cleaned up in addition to
+connections and ad-hoc proxy definitions are cleaned up in addition to
 killing all buffers related to remote connections.
 @end deffn
 
 @deffn Command tramp-cleanup-some-buffers
 Similar to @code{tramp-cleanup-all-buffers}, where all remote
-connections and ad-hoc proxy definition are cleaned up.  However,
+connections and ad-hoc proxy definitions are cleaned up.  However,
 additional buffers are killed only if one of the functions in
 @code{tramp-cleanup-some-buffers-hook} returns @code{t}.
 @end deffn
@@ -4801,6 +4801,19 @@ remote buffers which are linked to a remote file, remote @code{dired}
 buffers, and buffers related to a remote process are cleaned up.
 @end defopt
 
+@deffn Command tramp-cleanup-bufferless-connections
+
+Similar to @code{tramp-cleanup-all-connections}, remote connections and
+ad-hoc proxy definitions are flushed, but limited to those connections
+for which no associated buffers exist (except for Tramp internal
+buffers).
+
+This command is helpful to prune connections after you close remote-file
+buffers without having to either cherry pick via
+@code{tramp-cleanup-connection} or clear them all via
+@code{tramp-cleanup-all-connections}.
+@end deffn
+
 
 @node Renaming remote files
 @section Renaming remote files

etc/NEWS

@@ -950,6 +950,14 @@ we invite Flyspell users to enable this new option and report issues.
 
 ** Tramp
 
++++
+*** New command 'tramp-cleanup-bufferless-connections'.
+Connection-related objects for which no associated buffers exist, except
+for Tramp internal buffers, are flushed.  This is helpful to prune
+connections after you close remote-file buffers without having to either
+cherry pick via 'tramp-cleanup-connection' or clear them all via
+'tramp-cleanup-all-connections'.
+
 +++
 *** Connection method "kubernetes" supports now optional namespace.
 The host name for Kubernetes connections can be of kind

lisp/net/tramp-cmds.el

@@ -101,12 +101,35 @@ SYNTAX can be one of the symbols `default' (default),
 ;; Use `match-buffers' starting with Emacs 29.1.
 ;;;###tramp-autoload
 (defun tramp-list-remote-buffers ()
-  "Return a list of all buffers with remote `default-directory'."
+  "Return a list of remote buffers, excluding internal tramp buffers.
+A buffer is considered remote if either its `default-directory' or its
+buffer file name is a remote file name."
   (tramp-compat-seq-keep
-   (lambda (x)
-     (when (tramp-tramp-file-p (tramp-get-default-directory x)) x))
+   (lambda (buffer)
+     (when (tramp-tramp-file-p
+            (or (buffer-file-name buffer)
+                (tramp-get-default-directory buffer)))
+       buffer))
    (buffer-list)))
 
+;;;###tramp-autoload
+(defun tramp-list-remote-buffer-connections ()
+  "Return a list of all remote buffer connections.
+A buffer is considered remote if either its `default-directory' or the
+function `buffer-file-name' is a remote file name."
+  (seq-uniq
+   (mapcar (lambda (buffer)
+             (or
+              (when (buffer-file-name buffer)
+                (file-remote-p (buffer-file-name buffer)))
+              (when (tramp-get-default-directory buffer)
+                (file-remote-p (tramp-get-default-directory buffer)))))
+           ;; Eliminate false positives from internal tramp buffers
+           (seq-remove
+            (lambda (buffer)
+              (member (buffer-name buffer) (tramp-list-tramp-buffers)))
+            (tramp-list-remote-buffers)))))
+
 ;;; Cleanup
 
 ;;;###tramp-autoload
@@ -321,6 +344,22 @@ non-nil."
   (let ((tramp-cleanup-some-buffers-hook '(always)))
     (tramp-cleanup-some-buffers)))
 
+;;;###tramp-autoload
+(defun tramp-cleanup-bufferless-connections ()
+  "Flush connection-related objects for which no buffer exists.
+A bufferless connection is one for which no live buffer's
+`buffer-file-name' or `default-directory' is associated with that
+connection, except for Tramp internal buffers.
+Display a message of cleaned-up connections."
+  (interactive)
+  (when-let* ((bufferless-connections
+               (seq-difference
+                (mapcar #'tramp-make-tramp-file-name (tramp-list-connections))
+                (tramp-list-remote-buffer-connections))))
+    (message "Cleaning up %s" (mapconcat #'identity bufferless-connections ", "))
+    (dolist (connection bufferless-connections)
+      (tramp-cleanup-connection (tramp-dissect-file-name connection 'noexpand)))))
+
 ;;; Rename
 
 (defcustom tramp-default-rename-alist nil