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bug#21200: 25.0.50; xdisp.c: infinite loop when using invisibility specs
From: |
Eli Zaretskii |
Subject: |
bug#21200: 25.0.50; xdisp.c: infinite loop when using invisibility specs |
Date: |
Thu, 06 Aug 2015 22:36:13 +0300 |
> Date: Thu, 6 Aug 2015 18:26:05 +0000
> From: Pip Cet <pipcet@gmail.com>
>
> with the current git tree (revision 0aec2aac), I'm running into
> problems with an infinite loop in xdisp.c which I believe to be fixed
> by this patch, which is reasonably obvious:
>
> diff --git a/src/xdisp.c b/src/xdisp.c
> index e45cb87..7b221d4 100644
> --- a/src/xdisp.c
> +++ b/src/xdisp.c
> @@ -4221,6 +4221,8 @@ handle_invisible_prop (struct it *it)
> if (invis == 2)
> display_ellipsis_p = true;
> }
> +
> + charpos = end_charpos;
> }
> while (invis != 0 && endpos < len);
>
> in this loop:
>
> do
> {
> end_charpos = Fnext_single_property_change (charpos, Qinvisible,
> it->string, limit);
> if (INTEGERP (end_charpos))
> {
> endpos = XFASTINT (end_charpos);
> charpos = end_charpos;
> prop = Fget_text_property (end_charpos, Qinvisible, it->string);
> invis = TEXT_PROP_MEANS_INVISIBLE (prop);
> if (invis == 2)
> display_ellipsis_p = true;
> }
> }
> while (invis != 0 && endpos < len);
>
> Without the patch, we keep calling Fnext_property_change with the same
> arguments and expecting a different result, which obviously never
> happens. In fact it seems to me we only need one of charpos and
> end_charpos as the code currently stands, anyway. However, charpos =
> f(..., charpos, ...) might cause confusion.
>
> I can provide more detail if necessary, but as I said, it's a fairly
> obvious bug.
Yes, please provide the details, and preferably also a recipe where
you see the loop.
Thanks.