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Date: Fri, 04 Apr 2003 03:06:00 -0000
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From: Nigel Stewart <nigels@nigels.com>
Subject: Re: c++/1833
Reply-To: Nigel Stewart <nigels@nigels.com>
X-SW-Source: 2003-04/txt/msg00128.txt.bz2
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The following reply was made to PR c++/1833; it has been noted by GNATS.

From: Nigel Stewart <nigels@nigels.com>
To: Wolfgang Bangerth <bangerth@ices.utexas.edu>
Cc: gcc-gnats@gcc.gnu.org
Subject: Re: c++/1833
Date: Fri, 04 Apr 2003 12:58:54 +1000

 Wolfgang,
 
 Heeding your advice about aliasing rules, I've replaced
 the cast with a union.  Problem is solved.  However, I
 would suggest that gcc should provide warnings or errors
 in the case of being fed illegal code.
 
 float foo()
 {
 	assert(sizeof(unsigned int)==sizeof(float));
 	union { float f; unsigned int i; } tmp;
 	tmp.i = (127<<23) | (1<<22);
 	return tmp.f;
 }
 
 Thanks for your response, and my apologies for cluttering
 the bug database...
 
 N Stewart
 
 > Nigel,
 > the problem you sent has nothing to do with the problem described in PR 
 > 1833. You are violating aliasing rules. The code in the report is legal, 
 > yours is not.
 > 
 > W.