bug#67062: 30.0.50; [PATCH] Abbreviate the revision in 'vc-annotate' (for Git)

[Jim Porter <jporterbugs@gmail.com>]

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On 11/12/2023 11:11 AM, Eli Zaretskii wrote:
>> Date: Sun, 12 Nov 2023 11:07:38 -0800
>> Cc: 67062@debbugs.gnu.org
>> From: Jim Porter <jporterbugs@gmail.com>
>>
>> In any case, we don't necessarily need to provide a default
>> implementation for the 'short-revision' function. What about something
>> like this? I'm not sure it's better, but it does let us avoid defining a
>> no-op implementation for the "default backend".
> 
> Fine by me, except that I think this should be optional behavior.

Ok, how about this? If you think I should add a bit about this to the 
manual, let me know. However, it seems like a fairly minor thing to me, 
and I don't want to distract the manual reader from the more-useful parts.

(I also welcome a suggestion on a shorter name than 
'vc-annotate-abbreviate-revision-in-buffer-name', but I wanted to be 
careful not to give the impression that this would apply to the revision 
IDs that you see in the VC-Annotate buffer's *contents*. I guess I could 
abbreviate some of the existing words though, like "revision" -> "rev".)

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From 9726e1acb70d7d02648665cc259e174670ca839f Mon Sep 17 00:00:00 2001
From: Jim Porter <jporterbugs@gmail.com>
Date: Fri, 10 Nov 2023 18:42:29 -0800
Subject: [PATCH] Abbreviate the VC revision in vc-annotate's buffer name

* lisp/vc/vc-annotate.el
(vc-annotate-abbreviate-revision-in-buffer-name): New option...
(vc-annotate): ... use it, and try to call 'short-revision' when
requested.

* lisp/vc/vc-git.el (vc-git-short-revision): New function.
(vc-git--rev-parse): New optional argument SHORT.

* etc/NEWS: Announce this change (bug#67062).
---
 etc/NEWS               |  7 +++++++
 lisp/vc/vc-annotate.el | 13 ++++++++++++-
 lisp/vc/vc-git.el      | 14 +++++++++++---
 3 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index 767e4c27b43..df11757e18d 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -396,6 +396,13 @@ switches for shortlogs, such as the one produced by 'C-x v L'.
 *** Obsolete command 'vc-switch-backend' re-added as 'vc-change-backend'.
 The command was previously obsoleted and unbound in Emacs 28.
 
+---
+*** 'vc-annotate' can now abbreviate the revision in the buffer name.
+When the option 'vc-annotate-abbreviate-revision-in-buffer-name' is
+non-nil (the default), 'vc-annotate' will use an abbreviated revision
+in its buffer name if the VC backend has a 'vc-BACKEND-short-revision'
+function.
+
 ** Diff mode
 
 +++
diff --git a/lisp/vc/vc-annotate.el b/lisp/vc/vc-annotate.el
index de6c3adbbdb..cacf05db6d9 100644
--- a/lisp/vc/vc-annotate.el
+++ b/lisp/vc/vc-annotate.el
@@ -162,6 +162,11 @@ vc-annotate-menu-elements
   :type '(repeat number)
   :group 'vc)
 
+(defcustom vc-annotate-abbreviate-revision-in-buffer-name t
+  "If non-nil, \\[vc-annotate] will use short revisions in its buffer name."
+  :type 'boolean
+  :group 'vc)
+
 (defvar-keymap vc-annotate-mode-map
   :doc "Local keymap used for VC-Annotate mode."
   "a"   #'vc-annotate-revision-previous-to-line
@@ -409,7 +414,13 @@ vc-annotate
 				  nil nil "20")))))))
   (vc-ensure-vc-buffer)
   (setq vc-annotate-display-mode display-mode) ;Not sure why.  --Stef
-  (let* ((temp-buffer-name (format "*Annotate %s (rev %s)*" (buffer-name) rev))
+  (let* ((displayed-rev
+          (or (and vc-annotate-abbreviate-revision-in-buffer-name
+                   (ignore-errors (vc-call-backend (vc-backend file)
+                                                   'short-revision rev)))
+              rev))
+         (temp-buffer-name (format "*Annotate %s (rev %s)*" (buffer-name)
+                                   displayed-rev))
          (temp-buffer-show-function 'vc-annotate-display-select)
          ;; If BUF is specified, we presume the caller maintains current line,
          ;; so we don't need to do it here.  This implementation may give
diff --git a/lisp/vc/vc-git.el b/lisp/vc/vc-git.el
index 707fc7cfc07..05216701fa9 100644
--- a/lisp/vc/vc-git.el
+++ b/lisp/vc/vc-git.el
@@ -403,6 +403,11 @@ vc-git-working-revision
   (let (process-file-side-effects)
     (vc-git--rev-parse "HEAD")))
 
+(defun vc-git-short-revision (rev)
+  "Return an abbreviated version of the revision REV."
+  (let (process-file-side-effects)
+    (vc-git--rev-parse rev 'short)))
+
 (defun vc-git--symbolic-ref (file)
   (or
    (vc-file-getprop file 'vc-git-symbolic-ref)
@@ -1830,11 +1835,14 @@ vc-git-previous-revision
     ;; does not (and cannot) quote.
     (vc-git--rev-parse (concat rev "~1"))))
 
-(defun vc-git--rev-parse (rev)
+(defun vc-git--rev-parse (rev &optional short)
   (with-temp-buffer
     (and
-     (vc-git--out-ok "rev-parse" rev)
-     (buffer-substring-no-properties (point-min) (+ (point-min) 40)))))
+     (apply #'vc-git--out-ok "rev-parse"
+            (append (when short '("--short"))
+                    (list rev)))
+     (goto-char (point-min))
+     (buffer-substring-no-properties (point) (pos-eol)))))
 
 (defun vc-git-next-revision (file rev)
   "Git-specific version of `vc-next-revision'."
-- 
2.25.1