From: Jonathan Wakely <jwakely.gcc@gmail.com>
To: "Andy Falanga (afalanga)" <afalanga@micron.com>
Cc: "gcc-help@gcc.gnu.org" <gcc-help@gcc.gnu.org>
Subject: Re: Possible bug in gcc 4.4.7
Date: Wed, 17 Sep 2014 23:57:00 -0000 [thread overview]
Message-ID: <CAH6eHdTv3DsVCtpB3nap=3LHUGCYFoQ1DuSvz_zuuxN=Fh_cpw@mail.gmail.com> (raw)
In-Reply-To: <60F6FAE47D1BCE4380CC06D18F49789B93F81CD4@NTXBOIMBX02.micron.com>
On 17 September 2014 18:15, Andy Falanga (afalanga) wrote:
>> That reinterpret_cast looks dodgy to me, accessing the object through a
>> different type is undefined behaviour. What's wrong with doing it
>> safely?
>>
>> Flag operator &=(Flag& f1, Flag f2) {
>> unsigned int i = f1;
>> i &= static_cast<unsigned int>(f2);
>> return f1 = static_cast<Flag>(i);
>> }
>
> Ha, nothing except my thinking that, because I was casting a reference, I had to use reinterpret_cast<>.
Well yes, if you want to cast T& to X& and T and X are not related by
inheritance then you do need to use reinterpret_cast, but that should
make you think "maybe this is not a valid cast, maybe I shouldn't do
it" rather than "if I use reinterpret_cast the compiler doesn't
complain so it must be the way to go".
prev parent reply other threads:[~2014-09-17 23:57 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-17 16:17 Andy Falanga (afalanga)
2014-09-17 17:00 ` Jonathan Wakely
2014-09-17 17:15 ` Andy Falanga (afalanga)
2014-09-17 18:05 ` Andrew Haley
2014-09-17 20:34 ` Andy Falanga (afalanga)
2014-09-18 0:12 ` Jonathan Wakely
2014-09-18 14:25 ` Andy Falanga (afalanga)
2014-09-18 17:42 ` Jonathan Wakely
2014-09-18 20:40 ` Andy Falanga (afalanga)
2014-09-17 23:57 ` Jonathan Wakely [this message]
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='CAH6eHdTv3DsVCtpB3nap=3LHUGCYFoQ1DuSvz_zuuxN=Fh_cpw@mail.gmail.com' \
--to=jwakely.gcc@gmail.com \
--cc=afalanga@micron.com \
--cc=gcc-help@gcc.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.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).