bug#50226: 27.1; Fix uncomment-region with space-only comment-continue

[Christophe Troestler]

In the Emacs development branch, `comment-region-default-1' has been fixed to 
handle the case 'comment-continue' is entirely made of whitespace (commit 
5c93063129).  However, `uncomment-region-default-1' did not receive an 
appropriate fix as the following test shows: 

--8<---------------cut here---------------start------------->8---
(let ((comment-style 'multi-line)
      (comment-continue "   ")
      (text "  a\n  b"))
  (equal text
         (with-temp-buffer
           (c-mode)
           (insert text)
           (comment-region (point-min) (point-max))
           (uncomment-region (point-min) (point-max))
           (buffer-string))))
--8<---------------cut here---------------end--------------->8---

The attached patch fixes that.

Best,
C.



In GNU Emacs 27.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.24, cairo 
version 1.16.0)
 of 2021-03-28, modified by Debian built on x86-conova-01
Windowing system distributor 'The X.Org Foundation', version 11.0.12011000
System Description: Debian GNU/Linux 11 (bullseye)

Recent messages:
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Checking 180 files in /usr/share/emacs/27.1/lisp/emacs-lisp...
Checking 24 files in /usr/share/emacs/27.1/lisp/cedet...
Checking 59 files in /usr/share/emacs/27.1/lisp/calendar...
Checking 87 files in /usr/share/emacs/27.1/lisp/calc...
Checking 113 files in /usr/share/emacs/27.1/lisp/obsolete...
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Memory information:
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>From c0d9a34a7f0a5955002429da0480aaf3913cd061 Mon Sep 17 00:00:00 2001
From: Christophe Troestler <Christophe.Troestler@umons.ac.be>
Date: Fri, 27 Aug 2021 16:14:08 +0200
Subject: [PATCH] lisp/newcomment.el: Uncommenting with whitespace
 `comment-continue'
Content-Type: text/plain; charset="utf-8"

---
 lisp/newcomment.el | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lisp/newcomment.el b/lisp/newcomment.el
index 57a52effd1..b458f0356d 100644
--- a/lisp/newcomment.el
+++ b/lisp/newcomment.el
@@ -932,7 +932,8 @@ uncomment-region-default-1
   (setq end (copy-marker end))
   (let* ((numarg (prefix-numeric-value arg))
         (ccs comment-continue)
-        (srei (comment-padright ccs 're))
+        (srei (or (comment-padright ccs 're)
+                  (and (stringp comment-continue) comment-continue)))
         (csre (comment-padright comment-start 're))
         (sre (and srei (concat "^\\s-*?\\(" srei "\\)")))
         spt)
-- 
2.32.0