From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Dan Nicolaescu <dann@gnu.org>
Cc: 6740@debbugs.gnu.org
Subject: bug#6740: Spurious byte compiler warnings
Date: Tue, 27 Jul 2010 23:40:50 +0200 [thread overview]
Message-ID: <jwvvd80iozu.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <yxqmxtcwu1w.fsf@fencepost.gnu.org> (Dan Nicolaescu's message of "Tue, 27 Jul 2010 16:26:03 -0400")
>> 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.
Stefan
next prev parent reply other threads:[~2010-07-27 21:40 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 [this message]
2020-11-19 4:25 ` Stefan Kangas
2020-11-24 6:40 ` Lars Ingebrigtsen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=jwvvd80iozu.fsf-monnier+emacs@gnu.org \
--to=monnier@iro.umontreal.ca \
--cc=6740@debbugs.gnu.org \
--cc=dann@gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this external index
https://git.savannah.gnu.org/cgit/emacs.git
https://git.savannah.gnu.org/cgit/emacs/org-mode.git
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.