Re: xdisp.c's struct it questions.

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sun, 4 Oct 2015 13:44:31 +0000
> Cc: emacs-devel@gnu.org
> From: Alan Mackenzie <acm@muc.de>
> 
> The biggest time sink for me at the moment is the vagueness in xdisp.c's
> use of the word "line".  Sometimes it means a screen line, sometimes it
> means a text line.

Yes, that's true.  The reason is the desire to keep identifier names
shorter, I guess.

> An example is `forward_to_next_line_start'.  It sounds like just what I
> need, but is it?  If it were called `forward_to_next_screen_line_start',
> or `forward_to_next_text_line_start', I could save myself an awful lot
> of poring through source code.

All the forward_to_*_line and back_to_*_line functions mean physical
lines.

If you need to move to the next screen line, you need to call
move_it_to instead.

> Even the comments preceding these routines tend to be vague about
> this.

The comments mention a newline, which is a clear sign they mean a
physical line.