Re: [boost] Re: basic guarantees in variant

From: Brian McNamara (lorgon_at_[hidden])
Date: 2003-10-09 15:28:59

On Thu, Oct 09, 2003 at 01:00:35PM -0700, E. Gladyshev wrote:
> --- Brian McNamara <lorgon_at_[hidden]> wrote:
> > This is clever.  Is it legal?  I know it's legal for POD types.  I can't
> > find text in the standard which makes it legal for non-POD types.  But
> > at the same time, offhand I can't imagine an implementation where it
> > wouldn't work.
> 
> Brian, where in my code do you see non-POD copying?
> All it does, it copies one char[] to another char[] 
> (both are POD types).
> The char arrays where allocated as char arrays 
> originally, there is not any casting going on.
> What are you concerns exactly?

My concern is that it is undefined behavior.  As others have pointed
you (and me!) to, read

   http://aspn.activestate.com/ASPN/Mail/Message/boost/1311813

Whether or not this _ought_ to be undefined behavior is perhaps up for
debate.  But the consensus among the language lawyers is that you are
simply not allowed to do this in C++ as it stands today, and I believe
them.  You should too.

-- 
-Brian McNamara (lorgon_at_[hidden])