* lisp/vc/log-edit.el (log-edit-diff-function): Document.

(cherry picked from commit c7a1fafa992b217014430fb30fd09c8e037227e0)

diff --git a/lisp/vc/log-edit.el b/lisp/vc/log-edit.el
index 58f4cc2c2b6477ff85d51c78ea343b70faf837d4..6176cf3589dc4c2df9a9c2b7ff9608bfb822b429 100644 (file)
--- a/lisp/vc/log-edit.el
+++ b/lisp/vc/log-edit.el
@@ -246,7 +246,11 @@ when this variable is set to nil.")
 (defvar log-edit-initial-files nil)
 (defvar log-edit-callback nil)
 (defvar log-edit-diff-function
-  (lambda () (error "Diff functionality has not been set up")))
+  (lambda () (error "Diff functionality has not been set up"))
+  "Function to display an appropriate Diff Mode buffer for the change.
+Called by the `log-edit-show-diff' command.
+Should not leave the Diff Mode buffer's window selected; that is, the
+Log Edit buffer's window should be selected when the function returns.")
 (defvar log-edit-listfun nil)
 
 (defvar log-edit-parent-buffer nil)