Date: Thu, 06 Aug 1998 09:22:37 -0700 From: John Polstra <jdp@polstra.com> To: Nicolas.Souchu@prism.uvsq.fr Cc: hackers@FreeBSD.ORG Subject: Re: C and static initialization with unions Message-ID: <199808061622.JAA26353@austin.polstra.com> In-Reply-To: <19980806113159.49110@breizh.prism.uvsq.fr> References: <199808050103.SAA27705@usr02.primenet.com> <199808050149.SAA01073@dingo.cdrom.com> <19980806113159.49110@breizh.prism.uvsq.fr>
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In article <19980806113159.49110@breizh.prism.uvsq.fr>,
Nicolas Souchu <Nicolas.Souchu@prism.uvsq.fr> wrote:
> Archie said:
>
> >>>
> One non-portable nicety of gcc is that you can do this:
>
> union foo {
> int iarg;
> char carg;
> };
>
> static union foo x = { carg: 12 };
>
> -Archie
> <<<
>
> Is it allowed in FreeBSD?
You can do anything you want in the privacy of your own home. But
I would strongly oppose the use of this extension in any code being
committed into FreeBSD itself. I suspect Bruce would make some noise
about it too. Surely you can find a portable way to accomplish what
you want to do, even if it means executing a few lines of code at run
time.
> Is all FreeBSD C source code portable?
GCC extensions are occasionally used in FreeBSD. However, they
are virtually always optional and for the purpose of (a) better
efficiency, or (b) better compiler warnings. When GCC extensions are
used, they are protected by "#ifdef __GNUC__", and an alternative
portable implementation is provided in the "#else" clause. For case
(a) the alternative implementation is less efficient; for case (b),
it's a no-op. See <sys/cdefs.h> for some examples of (b).
--
John Polstra jdp@polstra.com
John D. Polstra & Co., Inc. Seattle, Washington USA
"Self-knowledge is always bad news." -- John Barth
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