From: Alan Mackenzie <acm@muc.de>
To: Chong Yidong <cyd@gnu.org>
Cc: emacs-devel@gnu.org
Subject: Another bug in CC Mode's state cache.
Date: Fri, 20 Apr 2012 20:04:50 +0000 [thread overview]
Message-ID: <20120420200450.GA3541@acm.acm> (raw)
Hi, Yidong.
I've found and corrected another CC Mode state cache bug. It occurred in
situations like this:
{ } ( { }
a b c e f
Insert a closing paren after c:
{ } ( ) { }
a b c d e f
Previously, the backward search from e for a brace pair was bounded by
the paren at c. After the insertion of d, the the paren pair c-d is
invisible to backward searching, hence the brace pair a-b is spuriously
found, leading to a cache corruption.
The solution is to use the cache's memory of c rather than the paren in
the buffer to bound the search. This works. I have tested it on 100,000
random points in xdisp.c and 20,000 points in lisp.h. The results with
the new bugfix are identical to those without.
This clearly isn't a "regression". Would it nevertheless be OK to
install this fix in the Emacs 24 branch?
--
Alan Mackenzie (Nuremberg, Germany).
next reply other threads:[~2012-04-20 20:04 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-20 20:04 Alan Mackenzie [this message]
2012-04-20 6:19 ` Another bug in CC Mode's state cache Leo
2012-04-21 7:22 ` Alan Mackenzie
2012-04-21 2:30 ` Stefan Monnier
2012-04-21 7:19 ` Alan Mackenzie
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