Fix bidi paragraph direction when inserting text at newline

* src/insdel.c (invalidate_buffer_caches): Invalidate the bidi
paragraph cache when inserting immediately after a newline.
(Bug#26083)

1 files changed, 7 insertions, 4 deletions

diff --git a/src/insdel.c b/src/insdel.c
index e4ad9a2dec3..0a2e07a343f 100644
--- a/src/insdel.c
+++ b/src/insdel.c
@@ -2001,18 +2001,21 @@ invalidate_buffer_caches (struct buffer *buf, ptrdiff_t start, ptrdiff_t end)
      see below).  */
   if (buf->bidi_paragraph_cache)
     {
-      if (start != end
-          && start > BUF_BEG (buf))
+      if (start > BUF_BEG (buf))
         {
           /* If we are deleting or replacing characters, we could
              create a paragraph start, because all of the characters
              from START to the beginning of START's line are
              whitespace.  Therefore, we must extend the region to be
-             invalidated up to the newline before START.  */
+             invalidated up to the newline before START.  Similarly,
+             if we are inserting characters immediately after a
+             newline, we could create a paragraph start if the
+             inserted characters start with a newline.  */
           ptrdiff_t line_beg = start;
           ptrdiff_t start_byte = buf_charpos_to_bytepos (buf, start);
+          int prev_char = BUF_FETCH_BYTE (buf, start_byte - 1);
 
-          if (BUF_FETCH_BYTE (buf, start_byte - 1) != '\n')
+          if ((start == end) == (prev_char == '\n'))
             {
               struct buffer *old = current_buffer;