Make application configurable in 'with-connection-local-variables'

* doc/lispref/variables.texi (Connection Local Variables):
Explain 'connection-local-default-application'.

* etc/NEWS: Mention 'connection-local-default-application'.

* lisp/files-x.el (connection-local-default-application): New variable.
(connection-local-criteria-for-default-directory): Use it.  (Bug#54405)

* test/lisp/files-x-tests.el
(files-x-test-with-connection-local-variables): Extend test.

1 files changed, 9 insertions, 5 deletions

diff --git a/lisp/files-x.el b/lisp/files-x.el
index 319bfe05655..0ae9fb076eb 100644
--- a/lisp/files-x.el
+++ b/lisp/files-x.el
@@ -722,14 +722,18 @@ will not be changed."
         (copy-tree connection-local-variables-alist)))
    (hack-local-variables-apply)))
 
+(defvar connection-local-default-application 'tramp
+  "Default application in connection-local functions, a symbol.
+This variable must not be changed globally.")
+
 (defsubst connection-local-criteria-for-default-directory (&optional application)
   "Return a connection-local criteria, which represents `default-directory'.
-If APPLICATION is nil, the symbol `tramp' is used."
+If APPLICATION is nil, `connection-local-default-application' is used."
   (when (file-remote-p default-directory)
-    `(:application ,(or application 'tramp)
-       :protocol   ,(file-remote-p default-directory 'method)
-       :user       ,(file-remote-p default-directory 'user)
-       :machine    ,(file-remote-p default-directory 'host))))
+    `(:application ,(or application connection-local-default-application)
+      :protocol    ,(file-remote-p default-directory 'method)
+      :user        ,(file-remote-p default-directory 'user)
+      :machine     ,(file-remote-p default-directory 'host))))
 
 ;;;###autoload
 (defmacro with-connection-local-variables (&rest body)