bug#71499: [PATCH] Make whitespace.el cleanup add missing final newline

["Björn Lindström" <bkhl@elektrubadur.se>]

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On Tue, Jun 11, 2024, at 20:16, Björn Lindström wrote:
> Hello,
>
> attaching patch to make the whitespace-cleanup and 
> whitespace-cleanup-region functions add a final newline to a file if 
> whitespace-style contains `missing-newline-at-eof
>
> I'm aware this somewhat replicates what setting `require-final-newline 
> would do, but I think since whitespace.el with this configuration 
> highlights this as an error, it should also clean it up when asked.
>
> Best wishes,
> Björn
> Attachments:
> * 0001-Make-whitespace.el-cleanup-add-missing-final-newline.patch

Sorry, somehow messed up the first patch I sent, now attaching a corrected one. Attaching the correct one here.

Best wishes,
Björn

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From 3e180674604f41de70198c3aaa3b0bc5cddf0a68 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Lindstr=C3=B6m?= <bkhl@elektrubadur.se>
Date: Tue, 11 Jun 2024 19:49:55 +0200
Subject: [PATCH] Make whitespace.el cleanup add missing final newline

* lisp/whitespace.el (whitespace-cleanup-region): if cleaning up at end
of file, add missing newline if indicated by whitespace-style.
---
 lisp/whitespace.el | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/lisp/whitespace.el b/lisp/whitespace.el
index bc23a8794eb..6f8bd0b8585 100644
--- a/lisp/whitespace.el
+++ b/lisp/whitespace.el
@@ -1465,6 +1465,11 @@ defun whitespace-cleanup-region
    If `whitespace-style' includes the value
    `space-after-tab::space', replace TABs by SPACEs.
 
+5. missing newline at end of file.
+   If `whitespace-style' includes the value `missing-newline-at-eof',
+   and the cleanup region includes the end of file, add a final newline
+   if it is not there already.
+
 See `whitespace-style', `indent-tabs-mode' and `tab-width' for
 documentation."
   (interactive "@r")
@@ -1545,7 +1550,14 @@ defun whitespace-cleanup-region
          ((memq 'space-before-tab::space whitespace-style)
           (whitespace-replace-action
            'untabify rstart rend
-           whitespace-space-before-tab-regexp 2))))
+           whitespace-space-before-tab-regexp 2)))
+        ;; PROBLEM 5: missing newline at end of file
+        (when (and (memq 'missing-newline-at-eof whitespace-style)
+                   (= (point-max) (without-restriction (point-max))))
+          (goto-char (point-max))
+          (when (re-search-backward ".\\'" nil t)
+            (goto-char (point-max))
+            (insert "\n"))))
       (set-marker rend nil))))		; point marker to nowhere
 
 
-- 
2.45.2