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To: bkorb@pacbell.net, dewar@gnat.com
Subject: Re: module level flags
Cc: gcc@gcc.gnu.org, zack@codesourcery.com
Message-Id: <20020929171646.0E8E2F2CB6@nile.gnat.com>
Date: Sun, 29 Sep 2002 10:31:00 -0000
From: dewar@gnat.com (Robert Dewar)
X-SW-Source: 2002-09/txt/msg01194.txt.bz2

<<where 'stumble' is not of type 'mumble' must be deemed a
hard error.  If it is both not a hard error and the compiler
is reserving the "right" (??) to render the resulting pointer
ineffective, then GCC is reserving the right to destroy
the workings of a program.  This is wrong.  I don't care
if the standard says otherwise.
>>


Surely if you take this attitude you should just turn off aliasing analysis.
Really we expect gcc to implement C by default, not C + "fixes" to the
standard that Bruce Korb thinks are obviously correct.

GCC is not "reserving the right to destroy the workings of a program", 
since this program simply does not meet the semantics of C. Just because
you expect some program whose semantics is not defined by the standard
to do something, does not mean that a C compiler wlil agree with your
analysis. 

There are lots of respects in which people write non-standard C and expect 
it to work. This particular case seems to me to be one that should never
have been expected to work (i.e. I don't see any formal definition of C
that guarantees this program will work -- if I am wrong on this, please point out the document,
but do not expect me to be impressed by what some individual *thinks* the 
language should be. That's not decisive :-)

Robert Dewar