Fix fill-flowed for large or nil values of fill-flowed-display-column

[Matthias Schmitt]

Hi,

`fill-flowed` currently does not work correctly when the variable 
`fill-flowed-display-column` is large or nil (no hard line breaks 
e.g. when using `visual-fill-column-mode`).
The origin of this behavior is that if `fill-region` does not 
break the current line but the current line should be merged with 
the next line moving a line forward is an error.

This patch is a rather dirty fix that checks if the current line 
should be merged with the following line (ending in SPC CRLF) 
before moving over it.


This is my first contribution to Emacs and the mailing list and I 
am happy to be a small part of the development of Emacs :)

Cheers,
Matthias


diff -u --label \#\<buffer\ flow-fill.el.gz\> --label \#\<buffer\ 
flow-fill.buffer\> /tmp/buffer-content-nY7QFh 
/tmp/buffer-content-zqOgJ3
--- #<buffer flow-fill.el.gz>
+++ #<buffer flow-fill.buffer>
@@ -157,11 +157,12 @@
              (delete-char -1))
            (delete-char 1)
            (ignore-errors
-               (let ((fill-prefix ""))
-                 (fill-region (line-beginning-position)
-                               (line-end-position)
-                              'left 'nosqueeze))))))
-        (forward-line 1)))))
+              (let ((fill-prefix ""))
+                (fill-region (line-beginning-position)
+                             (line-end-position)
+                             'left 'nosqueeze))))))
+        (unless (eq (char-before (line-end-position)) ?\s)
+          (forward-line 1))))))

(make-obsolete-variable 'fill-flowed-encode-tests nil "27.1")
(defvar fill-flowed-encode-tests)

Diff finished.  Thu Jan 27 13:06:47 2022