From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Alan Mackenzie <acm@muc.de>
Cc: emacs-pretest-bug@gnu.org, Chong Yidong <cyd@stupidchicken.com>,
3269@emacsbugs.donarmstrong.com,
Thomas Christensen <thomasc@thomaschristensen.org>,
emacs-devel@gnu.org
Subject: Re: bug#3269: 23.0.93; C-mode text highlighting
Date: Mon, 18 May 2009 22:24:02 -0400 [thread overview]
Message-ID: <jwvk54d262g.fsf-monnier+emacsbugreports@gnu.org> (raw)
In-Reply-To: <20090518213030.GD12920@muc.de> (Alan Mackenzie's message of "Mon, 18 May 2009 21:30:30 +0000")
>> > OK, here is a patch for half of the problem - it now fontifies a broken
>> > string in a #define properly
>> For some definition of "properly".
> The opening string quote (?\" or ?\') gets f-l-warning-face. The rest of
> the unclosed string (up to the first EOL which isn't escaped) gets
> f-l-string-face.
> Actually, that's not _quite_ "proper". A string with an even number of
> backslashes at an EOL is broken at that point, but the font locking
> doesn't show this (yet). I don't suppose that will bother you all that
> much. ;-)
I won't oppose the change, but just to be clear: I think that the
increased code complexity introduced by your patch is a worse problem
than the "improper" highlighting it tries to fix.
When code is syntactically incorrect, it's common/normal/expected for
the highlighting to be "incorrect". This "incorrect" behavior is
actually a good way for the user to notice that his code has problems.
So, from this point of view, there's no need to highlight the opening
string quote with f-l-warning-face: just looking back in the buffer
until you find the first char that is not font-locked as expected will
find the culprit without any need for any extra elisp code, and moreover
this method will work in many more cases.
In other words, messed-up highlighting for incorrect code is just as
good if not better than explicitly recognizing the incorrect code and
highlighting it with f-l-warning-face.
When I introduced the use of f-l-warning-face in C strings, it was not
to avoid messed-up highlighting, but rather to avoid apparently correct
highlighting for code that was actually incorrect/unportable (and even
accepted by GCC at that time).
>> I think this part is more important. I don't care much (if at all)
>> about how invalid code is highlighted.
> I agree it's important. I've got it working; what's more, the code
> doesn't advise any of the font lock functions for (>= emacs-major-version
> 22). I'll commit it tomorrow sometime.
Thanks,
Stefan
next prev parent reply other threads:[~2009-05-19 2:24 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <878wl1h5fw.fsf@ancient.thomaschristensen.org>
[not found] ` <20090514213924.GB2413@muc.de>
2009-05-18 15:06 ` bug#3269: 23.0.93; C-mode text highlighting Alan Mackenzie
2009-05-18 16:41 ` Chong Yidong
2009-05-18 21:16 ` Alan Mackenzie
2009-05-18 19:53 ` Stefan Monnier
2009-05-18 21:30 ` Alan Mackenzie
2009-05-19 2:24 ` Stefan Monnier [this message]
2009-05-19 10:26 ` Alan Mackenzie
2009-05-19 14:36 ` Stefan Monnier
2009-05-19 22:40 ` Alan Mackenzie
2009-05-20 10:31 ` Jim Meyering
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