Re: master d423017cae1: * lisp/vc/vc-dir.el (vc-dir-headers): Try a hints separator line.

Eli Zaretskii [28/Aug  9:03am +03] wrote:
> I apologize for not catching this discussion in time, but IMO this
> change is more backward-incompatible than it should be.  It's okay to
> add strike-through on terminals which support that, but why break
> those which don't and only have underline?  The argument that
> strike-through "seems about as common as underline" is the proverbial
> famous last words; we don't really need to have even a slightest risk
> here, because "we have the technology" to support both cases.
>
> So please let's fix the defface so that it uses strike-through when
> supported, otherwise uses underline, and let's augment the change in
> make-separator-line so that it also supports terminals without support
> for strike-through but which support underline.  Okay?

Yes, sure, let's support both.  I think like this?

diff --git a/lisp/simple.el b/lisp/simple.el
index 52cdfb1b946..34e49112998 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -748,8 +748,10 @@ separator-line
      :height 0.1 :background "#505050")
     (((type graphic) (background light))
      :height 0.1 :background "#a0a0a0")
+    (((supports :strike-through t))
+     :foreground "ForestGreen" :strike-through t)
     (t
-     :foreground "ForestGreen" :strike-through t))
+     :foreground "ForestGreen" :underline t))
   "Face for separator lines."
   :version "29.1"
   :group 'text)
@@ -760,12 +762,14 @@ make-separator-line
 
 If LENGTH is nil, use the window width."
   (if (or (display-graphic-p)
-          (display-supports-face-attributes-p '(:strike-through t)))
+          (display-supports-face-attributes-p '(:strike-through t))
+          (display-supports-face-attributes-p '(:underline t)))
       (if length
           (concat (propertize (make-string length ?\s) 'face 'separator-line)
                   "\n")
         (propertize "\n" 'face '(:inherit separator-line :extend t)))
-    ;; In terminals that don't support strike-through, use a line of dashes.
+    ;; In terminals that don't support underline or strike-through, use
+    ;; a line of dashes.
     (concat (propertize (make-string (or length (1- (window-width))) ?-)
                         'face 'separator-line)
             "\n")))
-- 
Sean Whitton