From: Mikael Pettersson <mikpe@csd.uu.se>
To: filia@softhome.net
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH][2.6.6-rc3] gcc-3.4.0 fixes
Date: Thu, 29 Apr 2004 23:46:41 +0200 (MEST) [thread overview]
Message-ID: <200404292146.i3TLkfI0019612@harpo.it.uu.se> (raw)
On Thu, 29 Apr 2004 11:30:25 +0200, Ihar 'Philips' Filipau wrote:
>Mikael Pettersson wrote:
>> This patch fixes three warnings from gcc-3.4.0 in 2.6.6-rc3:
>> - drivers/char/ftape/: use of cast-as-lvalue
>> if (get_unaligned((__u32*)ptr)) {
>> - ++(__u32*)ptr;
>> + ptr += sizeof(__u32);
>> } else {
>
> Can anyone explain what is the problem with this?
> To me it seems pretty ligitimate code - why it was outlawed in gcc 3.4?
>
> Previous code was agnostic to type of ptr, but you code presume ptr
>being char pointer (to effectively increment by 4 bytes).
'ptr' _is_ a char pointer, and the code (visible in the part of
the patch you didn't include) already performed pointer arithmetic
on it relying on it being a char pointer. The old code had no
sane reason at all for updating 'ptr' via a cast-as-lvalue.
cast-as-lvalue is not proper C, has dodgey semantics, and can
always be replaced by proper C.
next reply other threads:[~2004-04-29 21:57 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-04-29 21:46 Mikael Pettersson [this message]
2004-05-17 0:58 ` H. Peter Anvin
2004-06-01 14:52 ` Mikael Pettersson
2004-06-01 15:09 ` William Lee Irwin III
2004-06-01 15:35 ` Mikael Pettersson
2004-06-01 15:38 ` Andreas Schwab
2004-06-01 17:09 ` H. Peter Anvin
2004-06-01 17:14 ` H. Peter Anvin
2004-06-01 21:47 ` Mikael Pettersson
2004-06-01 17:27 ` Linus Torvalds
2004-06-01 19:34 ` Chris Wedgwood
2004-07-16 4:28 ` H. Peter Anvin
[not found] <1PX8S-5z2-23@gated-at.bofh.it>
2004-04-29 9:30 ` Ihar 'Philips' Filipau
2004-04-29 20:46 ` Paul Wagland
2004-04-29 20:54 ` Denis Vlasenko
2004-04-29 21:35 ` Ihar 'Philips' Filipau
-- strict thread matches above, loose matches on Subject: below --
2004-04-28 13:07 Mikael Pettersson
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=200404292146.i3TLkfI0019612@harpo.it.uu.se \
--to=mikpe@csd.uu.se \
--cc=filia@softhome.net \
--cc=linux-kernel@vger.kernel.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.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®