From: Juanma Barranquero <lekktu@gmail.com>
To: Alan Mackenzie <acm@muc.de>
Cc: Dan Nicolaescu <dann@gnu.org>, 6740@debbugs.gnu.org
Subject: bug#6740: Spurious byte compiler warnings
Date: Wed, 28 Jul 2010 21:54:04 +0200 [thread overview]
Message-ID: <AANLkTinPrue70-0fO0Z+S=594dok0CmzZfo5WKgf22xg@mail.gmail.com> (raw)
In-Reply-To: <20100728194511.GD2999@muc.de>
On Wed, Jul 28, 2010 at 21:45, Alan Mackenzie <acm@muc.de> wrote:
> I'm doubting
> its adequacy. Without understanding that (featurep 'xemacs) has been
> optimised to nil, it's impossible to understand the current message
I think the message is a good hint that something is being statically
determined to be nil inside an `and'.
> (either of them).
Yes, that's a bug :-)
> If only there were a warning about 'xemacs, it would be plain
> and obvious.
But, as I've explained, there cannot (easily) be a waning about
`xemacs'; it would have to be about any code that statically evaluates
to nil in such a context. I'm not sure how clean that would be to
implement, and anyway no one has been bothered enough to try it.
> Does anybody care about
> it enough to want that message in this particular case?
Yes. You don't know whether a warning is relevant or not unless you
get it. In *this* particular case, all you need to quiet the
byte-compiler is
@@ -1,5 +1,5 @@
(eval-when-compile
- (if (and (not (featurep 'cc-fix))
- (featurep 'xemacs)
+ (if (and (featurep 'xemacs)
+ (not (featurep 'cc-fix))
(progn
(require 'font-lock)
> Couldn't the
> optimisation just be done quietly in the background, with no warning?
Why? The optimization is detecting something suspicious, and acting
accordingly.
> Or couldn't there be a warning like
>
> "`(featurep 'xemacs)' has been translated to nil"
????
That's worse that what you're complaining now; every use of (featurep
'xemacs) in the sources would produce warnings!
Juanma
next prev parent reply other threads:[~2010-07-28 19:54 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-27 20:06 bug#6740: Spurious byte compiler warnings Alan Mackenzie
2010-07-27 20:26 ` Dan Nicolaescu
2010-07-27 21:23 ` Alan Mackenzie
2010-07-27 22:57 ` Juanma Barranquero
2010-07-28 17:49 ` Alan Mackenzie
2010-07-28 17:56 ` Juanma Barranquero
2010-07-28 19:45 ` Alan Mackenzie
2010-07-28 19:54 ` Juanma Barranquero [this message]
2010-07-28 23:00 ` Dan Nicolaescu
2010-07-29 20:24 ` Alan Mackenzie
2010-07-29 20:36 ` Juanma Barranquero
2010-07-27 21:40 ` Stefan Monnier
2020-11-19 4:25 ` Stefan Kangas
2020-11-24 6:40 ` Lars Ingebrigtsen
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