Re: basic VRP min/max range overflow question

["Joseph S. Myers" <joseph at codesourcery dot com>]

On Sat, 18 Jun 2005, Paul Schlie wrote:

>        [#1] Behavior,  upon  use  of  a  nonportable  or  erroneous
>        program  construct, of erroneous data, or of indeterminately
>        valued  objects,  for  which  this  International   Standard
>        imposes  no  requirements.   Permissible  undefined behavior
>        ranges  from  ignoring   the   situation   completely   with
>        unpredictable  results,  to  behaving  during translation or
>        program execution in a documented manner  characteristic  of
>        the   environment   (with  or  without  the  issuance  of  a
>        diagnostic  message),  to  terminating  a   translation   or
>        execution (with the issuance of a diagnostic message).

You appear to have chosen to misquote again.  In this case, you've taken 
the C90 version of the wording but with a paragraph number from C99 (C90 
did not have paragraph numbers).  Perhaps you cannot grasp the generality 
of "no requirements"?  A few examples are given, but "no requirements" 
means that the program can behave completely inconsistently if it involves 
undefined behavior.

>        [#3] The implementation must successfully translate a  given
>        program  unless  a syntax error is detected, a constraint is
>        violated, or it can determine that every possible  execution
>        of that program would result in undefined behavior.

This looks like a completely fabricated quote to me.  If it comes from 
C99, state the subclause and paragraph numbers (in C99 as amended by TC1 
and TC2).  It certainly doesn't seem to be in the plain text version of 
C99+TC1.  In general, state where you are quoting rather than just 
claiming particular text you've just written is relevant.

> Which again is specific to that which is defined, as it requires the
> successful (and presumably conformant) translation of the program unless
> the implementation can prove the whole program is itself would have an
> undefined behavior (reinforcing the notion that the language's semantics
> remain in force even in the presence of a expression with undefined
> semantics).

"no requirements" means that *any* translation conforms in the case of 
undefined behavior.  Only those executions not involving undefined 
behavior have any requirements.

-- 
Joseph S. Myers               http://www.srcf.ucam.org/~jsm28/gcc/
    jsm@polyomino.org.uk (personal mail)
    joseph@codesourcery.com (CodeSourcery mail)
    jsm28@gcc.gnu.org (Bugzilla assignments and CCs)