bug#25181: 25.1.90; move-beginning-of-line doesn't move point

[Andreas Röhler]

On 12.12.2016 17:53, Eli Zaretskii wrote:
> > From: Andreas Röhler <andreas.roehler@easy-emacs.de>
> > Date: Mon, 12 Dec 2016 12:49:05 +0100
> >
> > Bug does not appear with Emacs -Q, as some fontification in buffer seems
> > to trigger it.
> >
> > Text in buffer:
> >
> > git reset HEAD test/2.sh
> >
> > Cursor at pos 16. i.e. beginning of word "test".
> >
> > C-a doesn't move point.
> Please show a complete recipe, starting from "emacs -Q" (and loading
> any optional packages/customizations as needed).  It's hard to discuss
> an issue without being able to test-drive it.
>
> > Watching move-beginning-of-line edebug, at line 6415
> >
> >       (skip-chars-backward "^\n")
> >
> > jumps correctly to BOL.
> >
> > Error results from following later on:
> >
> >       (setq first-vis-field-value
> >         (constrain-to-field first-vis orig (/= arg 1) t nil))
> >
> > Here first-vis-field-value is set to orig, i.e. pos 16, where it jumps
> > back-to, not leaving point at BOL.
> I'm not sure I understood, but if I did, this is a feature: functions
> such as beginning-of-line stop moving at field boundaries.

Hmm, is this reasonable? BOL is a very basic concept. Don't think it 
should be permitted to be interfered with fields.