Re: adaptive-fill bug?

[Stefan Monnier]

> Could you explain the overall idea of this patch?

The patch makes two changes:

1. it removes the (looking-at paragraph-start) check on the second line of
   a paragraph.

2. it rejects fill-prefixes guessed by adaptive-fill-mode if they are longer
   than a line of text (longer than the difference between fill-column and
   left-margin).

The second part is the crucial one and should be 100% uncontroversial.
Such long prefixes don't make any sense anyway and are (in my experience)
always the result of matching a long line of dashes.  Also such a long
prefix makes the subsequent paragraph-fill fail miserably because it can
never find a place the cut the line(s) to stay within the fill-column.

The first part should be harmless as well: such a check used to be done on
both the first and the second line of a paragraph.  I removed the check on
the first line several years ago because it introduced a bug, and moved the
paragraph-start check further down, just before returning.  This late-check
also makes the second check unnecessary.

> Changes in the heuristics of adaptive-fill-mode are very risky.

I should know.  I'm the one who made each and every change in that area in
the last 3 years.

> Please don't go ahead and install it before we have this discussion.

Of course,


        Stefan