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From: Eric Botcazou <ebotcazou@libertysurf.fr>
To: Matt Austern <austern@apple.com>
Subject: Re: generalized lvalues -- patch outline
Date: Tue, 23 Nov 2004 21:10:00 -0000
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Cc: gcc@gcc.gnu.org,
 Nathan Sidwell <nathan@codesourcery.com>,
 Steve Naroff <snaroff@apple.com>,
 Michael Matz <matz@suse.de>,
 Ziemowit Laski <zlaski@apple.com>,
 Joe Buck <Joe.Buck@synopsys.com>,
 Andrew Pinski <pinskia@physics.uc.edu>,
 Mike Stump <mrs@apple.com>
References: <4D2CF60C-3919-11D9-8BD2-000A95BCF344@apple.com> <41A342FF.2080600@codesourcery.com> <8E7AE4A7-3D81-11D9-BE41-000A95AA5E5E@apple.com>
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> I haven't looked at that list, but one data point: CW restricts this
> cast to pointers, so that's good enough for CW compatibility.  I guess
> we learned just today (thanks, Eric!) that Solaris supports some
> version of this extension, at least for C.  We don't yet know the
> boundaries of Sun's version of the extension.

Since you so kindly asked... :-)

Sun seems to restrict it to pointers too, i.e. it rejects (short)v = 1 as well 
as:

void bar(unsigned long addr)
{
  *((int *)addr)++ = 1;
}

with:
"ext.c", line 8: a cast does not yield an lvalue
cc: acomp failed for ext.c


Here's the reaction of the C++ compiler:
poog% cat ext.C
void foo(char *p)
{
  *((long *) p)++ = 1;
}
poog% CC -S ext.C
"ext.C", line 3: Error: Operand for operator "++" must be an lvalue.
1 Error(s) detected.

-- 
Eric Botcazou