bug#14476: 24.3; mapping newline in buffer-display-table confuses posn-at-point

[Eli Zaretskii]

> From: Jonas Hörsch <coroa@online.de>
> Date: Sun, 26 May 2013 16:44:17 +0200
> 
> this bug ultimately leads to hard to understand column jumping in
> buffers where whitespace.el is active (and whitespace-style includes
> newline-mark). 
> 
> a small show case is provided by the following three expressions. the
> first two set it up. the third is to demonstrate the bug. tested in
> emacs 24.3.1 started with emacs -Q.
> 
> 
> (setq buffer-display-table (make-display-table))
> (aset buffer-display-table ?\n [?$ ?\n])
> (car (posn-x-y (posn-at-point)))
> 
> 
> ;; C-x C-e with point on the empty line right above this comment will
> ;; return the column 8 instead of the expected column 0. this leads to
> ;; seemingly erratic behaviour in some use-cases:
> ;; entering C-a (beginning-of-line) followed by C-n (next-line) will
> ;; leave point in column 1 instead of column 0

Fixed in revision 112745 on the trunk.

Thanks.