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Date: Wed, 18 Dec 2002 15:17:00 -0000
Message-ID: <20021218231703.32019.qmail@sources.redhat.com>
To: gcc-bugs@gcc.gnu.org, gcc-prs@gcc.gnu.org, hakonrk@fys.uio.no,
  nobody@gcc.gnu.org
From: reichelt@igpm.rwth-aachen.de
Reply-To: reichelt@igpm.rwth-aachen.de, gcc-bugs@gcc.gnu.org,
  gcc-prs@gcc.gnu.org, hakonrk@fys.uio.no, nobody@gcc.gnu.org,
  gcc-gnats@gcc.gnu.org
Subject: Re: c/8996: Unreliable bitfields
X-SW-Source: 2002-12/txt/msg00983.txt.bz2
List-Id: <gcc-prs.sourceware.org>

Synopsis: Unreliable bitfields

State-Changed-From-To: open->closed
State-Changed-By: reichelt
State-Changed-When: Wed Dec 18 15:17:02 2002
State-Changed-Why:
    Not a bug.
    
    Your program does not obey aliasing rules.
    You can use the option "-fno-strict-aliasing" as a workaround
    or you can correct your code:
    
    int main(void)
    {
            union {
                struct {
                        unsigned a :  8;
                        unsigned b : 23;
                        unsigned c :  1;
                } x;
                unsigned i;
            } u;
    
            u.i = -1;
            u.x.c = 1;
            u.x.b = 1;
            u.x.a = 0;
            printf("%08X\n", u.i);
    
            return 0;
    }

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=8996