Re: type-punned pointers!?

From:
"Victor Bazarov" <v.Abazarov@comAcast.net>
Newsgroups:
comp.lang.c++
Date:
Wed, 7 Jun 2006 16:04:28 -0400
Message-ID:
<e67bge$tgl$1@news.datemas.de>
Henrik Goldman wrote:

I'm seeing a weird problem on hp-ux (ia64) using g++ 4.1.1.


Have you tried news:gnu.g++.help ? If not, why not? If you have, what
did you find out?

Here below is a tiny bit of code which sets up the nessecary code for
doing a select():

fd_set fdread, fdwrite;


Are we supposed to know what 'fd_set' is?

FD_ZERO(&fdread);

FD_ZERO(&fdwrite);

FD_SET(m_IncomingSocket.GetSocket(), &fdread);

FD_SET(m_IncomingSocket.GetSocket(), &fdwrite);


Those 'FD_' things look like macros. How are they defined?

For the last two lines I get the following warning:

warning: dereferencing type-punned pointer will break strict-aliasing
rules warning: dereferencing type-punned pointer will break
strict-aliasing rules
I don't really understand why 'clean' code


What makes you believe the code is "'clean'"? What does it mean,
exactly?

would give such a warning
since it's structures which are defined by the system.
However perhaps someone could tell me what it actually means and
eventually how to solve it? My g++ optimization is O2.


If you haven't tried news:gnu.g++.help yet, go try it. Also, they
have an online forum (on their web site), IIRC. Don't discount it.
It's much more suitable for questions on a particular compiler's
behaviour than c.l.c++.

V
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