From: Geoff Keating <geoffk@geoffk.org>
To: xinant@cognigine.com
Cc: ian@zembu.com, binutils@sources.redhat.com
Subject: Re: "lang_statement_union_type and its usage?"
Date: Thu, 31 May 2001 13:56:00 -0000 [thread overview]
Message-ID: <200105312055.NAA19463@geoffk.org> (raw)
In-Reply-To: <3B16ADDC.80700@cognigine.com>
> Date: Thu, 31 May 2001 13:47:24 -0700
> From: xinant@cognigine.com (Xinan Tang)
> >
> > All elements of lang_statement_union start with
> > lang_statement_header_type header;
> > The first field in lang_statement_header_type is
> > union lang_statement_union *next;
> >
> > Therefore, in all cases, the first field in any instance of
> > lang_statement_union will be the next pointer.
> >
> > This is a pretty common hack when implementing derived classes in C.
> >
> > Ian
>
> I see. However, this may not work if some optimizing compilers
> would change the relative order of the `next' field. I.e., this scheme
> is compiler-dependent.
I believe that the C standard promises that this works.
--
- Geoffrey Keating <geoffk@geoffk.org>
next prev parent reply other threads:[~2001-05-31 13:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-05-31 11:57 Xinan Tang
2001-05-31 12:11 ` Ian Lance Taylor
2001-05-31 13:47 ` Xinan Tang
2001-05-31 13:56 ` Geoff Keating [this message]
2001-05-31 14:10 ` Ian Lance Taylor
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