bug#14303: 24.3; Bug in comment-search-backward

[Stefan Monnier]

>> I don't understand when that can happen (when inside a string (nth
>> 8 ppss) is also non-nil).
> I have
> (defvar octave-comment-start-skip "\\(^\\|\\S<\\)\\(?:%!\\|\\s<+\\)\\s-*"
>   "Octave-specific `comment-start-skip' (which see).")
> and this could find "#abc" as comment start where BEG is outside of
> strings and comments but END is in a string.

Ah, I see.  That's easy to fix: just check the syntax-ppss state at the
position about which you care, i.e. (or (match-end 1) (match-beginning 0)),
rather than at the position at which re-search-backward puts you.

> Maybe this is due to setting octave-comment-start-skip incorrectly.

> I looked at comment-normalize-vars and see it uses:
>   \\(\\(^\\|[^\\\n]\\)\\(\\\\\\\\\\)*\\)
> as anchor but I don't understand fully.

No, this is to try and avoid mis-recognizing \# (and \\\#, but not \\#)
as a comment starter when \ is an escape character.


        Stefan