bug#342: kill-line sometimes unexpectedly kills invisible text

[martin rudalics]

> current line is visible,
> next line is invisible,
> I move to end of visible line,
> then type ctrl-k.
> I expect it to kill just the visible newline,
> and sometimes it does that,
> but sometimes it kills the invisible line too.
>
> what's annoying is, it's inconsistent in an unobvious way.
> the behavior depends on what's in the invisible text.
>
> the underlying problem:
> kill-line in that case uses forward-visible-line
> to find the end of the kill region.

FWIW, your problem is caused by the

              (unless (bolp)
                (goto-char opoint))))

checks in `forward-visible-line' which get you back to the position
before the invisible text if that text does not end in a newline as with
the t2 part of your code.  Hence the invisible text won't be killed for
t2.  In the t1 part the invisible region ends in a newline and kill-line
will kill it along with the visible text.

I think the behavior of Emacs is consistent here but maybe not very
intuitive.  On the other hand I'm quite confident that changing that
behavior will break something else :-(