Re: parentheses matching failure on valid sexp

[martin rudalics]

> This bug is sensitive to the size of the input.  If you delete much of
> the input, then the bug goes away.

Emacs reports a bug because the matching left paren is more than
`blink-matching-paren-distance' characters before the right one.  The
message will go away if you customize that variable accordingly.

It might be worth looking at the syntax-ppss cache for paren matching.
I know, the paren matching algorithms usually find a matching paren
within a few characters distance and there's no profound reason to do
that.  But when font-locking is on, the cache contains the position of
all open parens for some line-beginning before point anyway.  Hence, we
could look for an opening paren within one or two lines and consult the
cache if we didn't find anything useful there.  In this case we could
ignore `blink-matching-paren-distance'.  Stefan what do you think?