Date: Tue, 04 Aug 1998 14:43:21 -0700 From: Ted Faber <faber@ISI.EDU> To: Warner Losh <imp@village.org> Cc: Nicolas Souchu <Nicolas.Souchu@prism.uvsq.fr>, FreeBSD Hackers <freebsd-hackers@FreeBSD.ORG> Subject: Re: C and static initialization with unions Message-ID: <199808042143.OAA15441@tnt.isi.edu> In-Reply-To: Your message of "Tue, 04 Aug 1998 13:50:49 MDT." <199808041950.NAA18579@harmony.village.org>
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Warner Losh wrote:
>In message <19980804185938.36803@breizh.prism.uvsq.fr> Nicolas Souchu writes:
>: static union foo_t bar = { (void *)&anyvar };
>:
>: The compiler says "warning, making integer from pointer without a cast"...
>: Which is true and could lead to bad asm code.
>
>static union foo_t bar = { (int)(void *)&anyvar };
>
>But it is unwise to assume that sizeof(int) == sizeof(void *).
The comp.lang.c FAQ (http://www.eskimo.com/~scs/C-faq/top.html)
suggests putting the member he wants to initialize first in the union,
where a conformant ANSI C compiler will initialize it correctly.
(http://www.eskimo.com/~scs/C-faq/q2.20.html)
Initializing with that cast defeats the point of using a union at all.
Not that this belongs in hackers...
- ----------------------------------------------------------------------
Ted Faber faber@isi.edu
USC/ISI Computer Scientist http://www.isi.edu/~faber
(310) 822-1511 x190 PGP Key: http://www.isi.edu/~faber/pubkey.asc
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