Subject: bug#79222: [PATCH] Fix fringe test in 'diff--font-lock-prettify'

From: john muhl <[email-masked]>
Date: Tue, 12 Aug 2025 00:03:35 -0500

Tags: patch

With diff-font-lock-prettify enabled opening a diff (or having Gnus try
to render one, &c) in a tty frame causes an error since 'left-fringe is
nil in that case.

  emacs -Q -nw -eval "(setopt diff-font-lock-prettify t)" some.diff

>From 50314aaae7287b03754315a5ad7aa922c417cdb2 Mon Sep 17 00:00:00 2001
From: john muhl <[email-masked]>
Date: Mon, 11 Aug 2025 17:43:20 -0500
Subject: [PATCH] Fix fringe width test in 'diff--font-lock-prettify'

* lisp/vc/diff-mode.el (diff--font-lock-prettify):
Use 'window-fringes' instead of the 'left-fringe' frame parameter
since the former returns an integer on both GUI and TTY frames.
---
 lisp/vc/diff-mode.el | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lisp/vc/diff-mode.el b/lisp/vc/diff-mode.el
index 31a505f19be..df72cecb749 100644
--- a/lisp/vc/diff-mode.el
+++ b/lisp/vc/diff-mode.el
@@ -2949,7 +2949,7 @@ 'diff-fringe-nul
 
 (defun diff--font-lock-prettify (limit)
   (when diff-font-lock-prettify
-    (when (> (frame-parameter nil 'left-fringe) 0)
+    (when (> (car (window-fringes)) 0)
       (save-excursion
         ;; FIXME: Include the first space for context-style hunks!
         (while (re-search-forward "^[-+! ]" limit t)
-- 
2.50.1