From: Stefan Kangas <stefan@marxist.se>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: Dan Nicolaescu <dann@gnu.org>, Alan Mackenzie <acm@muc.de>,
6740@debbugs.gnu.org
Subject: bug#6740: Spurious byte compiler warnings
Date: Wed, 18 Nov 2020 20:25:56 -0800 [thread overview]
Message-ID: <CADwFkmkFAAo9HDhi+Po_0VoyXNdZyFPi3-w2BZwCGZE8cvV1sA@mail.gmail.com> (raw)
In-Reply-To: <jwvvd80iozu.fsf-monnier+emacs@gnu.org> (Stefan Monnier's message of "Tue, 27 Jul 2010 23:40:50 +0200")
Stefan Monnier <monnier@iro.umontreal.ca> writes:
>>> Warning: value returned from (featurep (quote cc-fix)) is unused
>>> Warning: value returned from (featurep (quote cc-fix)) is unused
>>>
>>> It is obvious that that value is indeed used. This is a bug.
>
>> The byte compiler knows that (featurep 'xemacs) is false, so
>> (and (not (featurep 'cc-fix)) ... )
>> will be false, so the featurep result is indeed unused.
>
>> If you use (and (featurep 'xemacs) (not (featurep 'cc-fix) ...
>> the warning will go away.
>
> It's one of those cases where the warning is the result of a check done
> "too late" (i.e. after some optimization), which means the check is not
> performed on the code the user sees, but on some massaged version of it.
> It's difficult to avoid them, short of removing all "code
> improvement" warnings.
(That was 10 years ago.)
I think this is a very minor issue that is likely not worth spending any
time on. In any case, it's not even clear what the fix would be or if
a different behavior would improve the situation.
Does anyone object to closing this as wontfix?
next prev parent reply other threads:[~2020-11-19 4:25 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
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 [this message]
2020-11-24 6:40 ` Lars Ingebrigtsen
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