Re: display bug for empty lines in recent git snapshot

[Eli Zaretskii <eliz@gnu.org>]

> From: Giorgos Keramidas <keramida@ceid.upatras.gr>
> Cc: tassilo@member.fsf.org, emacs-devel@gnu.org
> Date: Wed, 17 Nov 2010 14:14:54 +0100
> 
> > The problem is that I installed a fix for displaying glyphless
> > characters using the zero-width method (see the change in
> > set_cursor_from_row in the changeset), and that fix inadvertently
> > introduced this bug.
> >
> > I will try to fix this as soon as possible.
> 
> That's ok.  I daily build new snapshots, and this is a very minor detail
> that doesn't have any serious consequences to the actual *data* of the
> buffer.  When you have a fix in the works, please feel free to forward
> me the patch for testing.

I think I fixed this now, patch below.

=== modified file 'src/ChangeLog'
--- src/ChangeLog	2010-11-17 15:12:02 +0000
+++ src/ChangeLog	2010-11-17 19:15:24 +0000
@@ -1,3 +1,8 @@
+2010-11-17  Eli Zaretskii  <eliz@gnu.org>
+
+	* xdisp.c (set_cursor_from_row): Fix cursor positioning in empty
+	lines on text-mode terminals.  (bug#7417)
+
 2010-11-17  Stefan Monnier  <monnier@iro.umontreal.ca>
 
 	* xterm.c (get_current_wm_state): Rename from get_current_vm_state.

=== modified file 'src/xdisp.c'
--- src/xdisp.c	2010-11-17 02:37:45 +0000
+++ src/xdisp.c	2010-11-17 19:15:24 +0000
@@ -12839,6 +12839,15 @@ set_cursor_from_row (struct window *w, s
 	&& BUFFERP (glyph->object) && glyph->charpos == pt_old)
       && bpos_covered < pt_old)
     {
+      /* An empty line has a single glyph whose OBJECT is zero and
+	 whose CHARPOS is the position of a newline on that line.
+	 Note that on a TTY, there are more glyphs after that, which
+	 were produced by extend_face_to_end_of_line, but their
+	 CHARPOS is zero or negative.  */
+      int empty_line_p =
+	(row->reversed_p ? glyph > glyphs_end : glyph < glyphs_end)
+	&& INTEGERP (glyph->object) && glyph->charpos > 0;
+
       if (row->ends_in_ellipsis_p && pos_after == last_pos)
 	{
 	  EMACS_INT ellipsis_pos;
@@ -12875,6 +12884,7 @@ set_cursor_from_row (struct window *w, s
 	       || (row->truncated_on_right_p && pt_old > bpos_max)
 	       /* Zero-width characters produce no glyphs.  */
 	       || (!string_seen
+		   && !empty_line_p
 		   && (row->reversed_p
 		       ? glyph_after > glyphs_end
 		       : glyph_after < glyphs_end)))