From owner-freebsd-current  Wed Feb 27  0:15:29 2002
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Date: Wed, 27 Feb 2002 19:09:52 +1100 (EST)
From: Bruce Evans <bde@zeta.org.au>
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To: Peter Wemm <peter@wemm.org>
Cc: Peter Dufault <dufault@hda.hda.com>,
	"M. Warner Losh" <imp@village.org>, <mike_makonnen@yahoo.com>,
	<current@FreeBSD.ORG>
Subject: Re: HEADS UP: cvs commit: src/sys/conf kern.pre.mk (fwd) 
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On Tue, 26 Feb 2002, Peter Wemm wrote:

> Peter Dufault wrote:
> > When it is too twisty to fix at the moment I use macros such as:
> >
> > #define BOGUSLY_CAST_AWAY_VOLATILITY(T,P) ((T)(unsigned int)(P))
> >
> > ...
> >
> > volatile int conspeed; int *foo =
> > 	BOGUSLY_CAST_AWAY_VOLATILITY(int *, &conspeed);
> >
> > to surpress the warnings.  You can easily redefine the macro to get
> > them back so together with the discouraging name you're not sweeping
> > things under the rug.
>
> In sys/cdefs.h, we have:
>
> #define     __DECONST(type, var)    ((type)(uintptr_t)(const void *)(var))
>
> .. but bde threatened bodily harm for using it if I recall correctly.

Sort of.  __DECONST() is not ugly enough, and even its implementations are
not ugly enough to be as correct as possible (spot the missing cast).

I was recently forced to "fix" a warning that was "fixed" using the
uintptr_t hack (missing a cast of course) in -current but not in my
version (pending a better fix).

Index: link_elf.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/link_elf.c,v
retrieving revision 1.51
diff -u -2 -r1.51 link_elf.c
--- link_elf.c	16 Nov 2001 21:08:37 -0000	1.51
+++ link_elf.c	27 Feb 2002 06:34:38 -0000
@@ -839,8 +840,9 @@
     elf_file_t ef = (elf_file_t) file;

-#ifdef DDB
+#if defined(DDB) && defined(__ELF__)
     if (ef->gdb.l_ld) {
 	GDB_STATE(RT_DELETE);
-	free((void *)(uintptr_t)ef->gdb.l_name, M_LINKER);
+	/* XXX extreme ugliness to avoid a cast-qual warning: */
+	free((void *)(uintptr_t)(const void *)ef->gdb.l_name, M_LINKER);
 	link_elf_delete_gdb(&ef->gdb);
 	GDB_STATE(RT_CONSISTENT);

Is this ugly enough?

Bruce


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