master b3d57d43979: * lisp/vc/vc-hooks.el (vc-display-status): New value 'no-backend' (bug#66464).

[Juri Linkov]

branch: master
commit b3d57d4397945e16edffe78d71fd1ce040f86967
Author: Juri Linkov <juri@linkov.net>
Commit: Juri Linkov <juri@linkov.net>

    * lisp/vc/vc-hooks.el (vc-display-status): New value 'no-backend' 
(bug#66464).
    
    * lisp/vc/vc-hooks.el (vc-default-mode-line-string): Use it.
    * lisp/vc/vc-git.el (vc-git-mode-line-string): Use it.
    * lisp/vc/vc-hg.el (vc-hg-mode-line-string): Use it.
---
 etc/NEWS            |  4 ++++
 lisp/vc/vc-git.el   |  4 +++-
 lisp/vc/vc-hg.el    |  4 +++-
 lisp/vc/vc-hooks.el | 12 +++++++++---
 4 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index 8324eb7da1e..58bb1c052f1 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -392,6 +392,10 @@ This is a string or a list of strings that specifies the 
Git log
 switches for shortlogs, such as the one produced by 'C-x v L'.
 'vc-git-log-switches' is no longer used for shortlogs.
 
+---
+*** New value 'no-backend' for user option 'vc-display-status'.
+With this value only the revision number is displayed on the mode-line.
+
 ---
 *** Obsolete command 'vc-switch-backend' re-added as 'vc-change-backend'.
 The command was previously obsoleted and unbound in Emacs 28.
diff --git a/lisp/vc/vc-git.el b/lisp/vc/vc-git.el
index 707fc7cfc07..2e057ecfaa7 100644
--- a/lisp/vc/vc-git.el
+++ b/lisp/vc/vc-git.el
@@ -423,7 +423,9 @@ in the order given by `git status'."
                (rev (vc-working-revision file 'Git))
                (disp-rev (or (vc-git--symbolic-ref file)
                              (and rev (substring rev 0 7))))
-               (state-string (concat backend-name indicator disp-rev)))
+               (state-string (concat (unless (eq vc-display-status 'no-backend)
+                                       backend-name)
+                                     indicator disp-rev)))
     (propertize state-string 'face face 'help-echo
                 (concat state-echo " under the " backend-name
                         " version control system"
diff --git a/lisp/vc/vc-hg.el b/lisp/vc/vc-hg.el
index 89b2814a0a3..9df517ea847 100644
--- a/lisp/vc/vc-hg.el
+++ b/lisp/vc/vc-hg.el
@@ -365,7 +365,9 @@ specific file to query."
                             (and vc-hg-use-file-version-for-mode-line-version
                                  truename)))))
                (rev (or rev "???"))
-               (state-string (concat backend-name indicator rev)))
+               (state-string (concat (unless (eq vc-display-status 'no-backend)
+                                       backend-name)
+                                     indicator rev)))
     (propertize state-string 'face face 'help-echo
                 (concat state-echo " under the " backend-name
                         " version control system"))))
diff --git a/lisp/vc/vc-hooks.el b/lisp/vc/vc-hooks.el
index c16fb63b2ff..8451128286b 100644
--- a/lisp/vc/vc-hooks.el
+++ b/lisp/vc/vc-hooks.el
@@ -152,8 +152,12 @@ visited and a warning displayed."
 
 (defcustom vc-display-status t
   "If non-nil, display revision number and lock status in mode line.
-Otherwise, not displayed."
-  :type 'boolean
+If nil, only the backend name is displayed.  When the value
+is `no-backend', then no backend name is displayed before the
+revision number and lock status."
+  :type '(choice (const :tag "Show only revision/status" no-backend)
+                 (const :tag "Show backend and revision/status" t)
+                 (const :tag "Show only backend name" nil))
   :group 'vc)
 
 
@@ -766,7 +770,9 @@ This function assumes that the file is registered."
                (rev (vc-working-revision file backend))
                (`(,state-echo ,face ,indicator)
                 (vc-mode-line-state state))
-               (state-string (concat backend-name indicator rev)))
+               (state-string (concat (unless (eq vc-display-status 'no-backend)
+                                       backend-name)
+                                     indicator rev)))
     (propertize state-string 'face face 'help-echo
                 (concat state-echo " under the " backend-name
                         " version control system"))))