bug#6205: 23.1; align.el error deleting a lot of whitespace

[Stefan Monnier]

John, what's your opinion?
The patch looks OK to me, but at the same time, the code is pretty
impenetrable from here,


        Stefan


>>>>> "Kevin" == Kevin Ryde <user42@zip.com.au> writes:

> If M-x align deletes a lot of whitespace doing its alignment it can get
> an "Invalid search bound" error.  Eg. with foo.el below

>     emacs -Q foo.el
>     M-x end-of-buffer
>     M-x align
>     => Invalid search bound (wrong side of point)

> In `align-region' it seems `last-point' is established from `b' which is
> an integer buffer position but that position is invalidated by
> whitespace deletes before that point (done by `align-regions').

> I get some joy from making the marker before changing the buffer, per
> below.  Alternately (untested!) perhaps `b' could be a marker to start
> with, ready to be the new value of `last-point'.

> 2010-05-17  Kevin Ryde  <user42@zip.com.au>

>       * align.el (align-region): For `last-point' take marker of b
>       position before align-regions because that function inserts or
>       deletes text before there.  In particular fixes "Invalid search
>       bound" when there's two sections in the region and alignment in
>       the first deletes a lot of whitespace.

> (ab        .    c)
> (def  .                                                                ghi)

> (ab        .    c)

> (foo . bar)
> (foo . bar)

> --- align.el.~1.35.~  2009-03-28 09:41:43.000000000 +1100
> +++ align.el  2010-05-16 19:03:40.000000000 +1000
> @@ -1502,10 +1502,10 @@
>                                  (align-new-section-p last-point b
>                                                       thissep))
>                             (progn
> +                             (setq last-point (copy-marker b t))
>                               (align-regions regions align-props
>                                              rule func)
> -                             (setq last-point (copy-marker b t)
> -                                   regions nil
> +                             (setq regions nil
>                                     align-props nil))
>                           (setq last-point (copy-marker b t)))
 





> In GNU Emacs 23.1.1 (i486-pc-linux-gnu, GTK+ Version 2.16.5)
>  of 2009-09-14 on raven, modified by Debian
> configured using `configure  '--build=i486-linux-gnu' '--host=i486-linux-gnu' 
> '--prefix=/usr' '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib' 
> '--localstatedir=/var/lib' '--infodir=/usr/share/info' 
> '--mandir=/usr/share/man' '--with-pop=yes' 
> '--enable-locallisppath=/etc/emacs23:/etc/emacs:/usr/local/share/emacs/23.1/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/23.1/site-lisp:/usr/share/emacs/site-lisp:/usr/share/emacs/23.1/leim'
>  '--with-x=yes' '--with-x-toolkit=gtk' '--with-toolkit-scroll-bars' 
> 'build_alias=i486-linux-gnu' 'host_alias=i486-linux-gnu' 'CFLAGS=-DDEBIAN -g 
> -O2' 'LDFLAGS=-g' 'CPPFLAGS=''

> Important settings:
>   value of $LC_ALL: nil
>   value of $LC_COLLATE: nil
>   value of $LC_CTYPE: nil
>   value of $LC_MESSAGES: nil
>   value of $LC_MONETARY: nil
>   value of $LC_NUMERIC: nil
>   value of $LC_TIME: nil
>   value of $LANG: en_AU
>   value of $XMODIFIERS: nil
>   locale-coding-system: iso-latin-1-unix
>   default-enable-multibyte-characters: t