Re: Highlight current line when using gud

[Condy Chen <condy0919@gmail.com>]

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What it looks like in emacs -Q.

Before this patch, dark theme users cannot distinguish the line from the
background even though hl-line-mode is enabled. Personally I can't.
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Furthermore,  users must set hl-line-sticky-flag to t to enable highlight
in all windows or move the point to the source file buffer, otherwise only
the arrow in fringe is helpful for which line program run to. It's too
restricted in such a situation.

So I propose to add a new overlay of current line to make gud more friendly
and deprecate the old one.

Here is my patch. :-)

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From 1b896f5e7f351cabbc43c7ce730e17d43e4dfc7f Mon Sep 17 00:00:00 2001
From: condy <condy0919@gmail.com>
Date: Wed, 30 Jun 2021 03:57:09 +0800
Subject: [PATCH] * lisp/progmodes/gud.el: Highlight current line

---
 lisp/progmodes/gud.el | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/lisp/progmodes/gud.el b/lisp/progmodes/gud.el
index 740a6e2581..7f1ec20e47 100644
--- a/lisp/progmodes/gud.el
+++ b/lisp/progmodes/gud.el
@@ -85,6 +85,9 @@ gud
   :group 'processes
   :group 'tools)
 
+(defface gud-highlight-face '((t (:inherit secondary-selection)))
+  "Face to use to highlight current line."
+  :group 'gud)
 
 (defcustom gud-key-prefix "\C-x\C-a"
   "Prefix of all GUD commands valid in C buffers."
@@ -2768,6 +2771,7 @@ gud-filter
 	      (gud-filter proc ""))))))
 
 (defvar gud-minor-mode-type nil)
+(defvar gud-overlay-line nil)
 (defvar gud-overlay-arrow-position nil)
 (add-to-list 'overlay-arrow-variable-list 'gud-overlay-arrow-position)
 
@@ -2791,6 +2795,9 @@ gud-sentinel
 	((memq (process-status proc) '(signal exit))
 	 ;; Stop displaying an arrow in a source file.
 	 (setq gud-overlay-arrow-position nil)
+         ;; Stop displaying the `gud-overlay-line'.
+         (delete-overlay gud-overlay-line)
+         (setq gud-overlay-line nil)
 	 (if (eq (buffer-local-value 'gud-minor-mode gud-comint-buffer)
 		   'gdbmi)
 	     (gdb-reset)
@@ -2886,6 +2893,11 @@ gud-display-line
 	  (or gud-overlay-arrow-position
 	      (setq gud-overlay-arrow-position (make-marker)))
 	  (set-marker gud-overlay-arrow-position (point) (current-buffer))
+          ;; Update the position of `gud-overlay-line'
+          (unless gud-overlay-line
+            (setq gud-overlay-line (make-overlay (point) (point)))
+            (overlay-put gud-overlay-line 'face 'gud-highlight-face))
+          (move-overlay gud-overlay-line (line-beginning-position) (line-end-position) (current-buffer))
 	  ;; If they turned on hl-line, move the hl-line highlight to
 	  ;; the arrow's line.
 	  (when (featurep 'hl-line)
-- 
2.32.0