From: Alan Mackenzie <acm@muc.de>
To: Stefan Monnier <monnier@iro.umontreal.ca>
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: Tue, 19 May 2009 10:26:19 +0000 [thread overview]
Message-ID: <20090519102619.GA1317@muc.de> (raw)
In-Reply-To: <jwvk54d262g.fsf-monnier+emacsbugreports@gnu.org>
Hi, Stefan,
On Mon, May 18, 2009 at 10:24:02PM -0400, Stefan Monnier wrote:
> > 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. ;-)
Whoops! I was utterly wrong there. When a string inside a #define has
an even number of backslashes at an EOL, this is perfectly legal; the
last \ escapes the EOL, concatenating the lines, and the second last \
escapes the first character on the next line. Nice simple language, C.
;-)
> 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.
Well, I don't agree with that, but I'm beginning to think that the
current fontification (ommitting f-l-string-face until the closing " is
there) wasn't perhaps quite so bad after all.
> When code is syntactically incorrect, it's common/normal/expected for
> the highlighting to be "incorrect".
Where "incorrect" here means "different from what it would be if the code
were correct".
> This "incorrect" behavior is actually a good way for the user to notice
> that his code has problems.
Agreed, totally.
> 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.
I was thinking of "compatibility" with unterminated strings in normal
code. But they're not the same thing. An open string in a #define is
perfectly valid code, if somewhat unusual outside of the Obfuscated C
competition.
You've persuaded me that the existing fontification is actually better.
So I won't be committing yesterday's patch. Thanks!
I'll just finish the other patch and commit that.
> Stefan
--
Alan Mackenzie (Nuremberg, Germany).
next prev parent reply other threads:[~2009-05-19 10:26 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
2009-05-19 10:26 ` Alan Mackenzie [this message]
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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