Re: [patch, wrong-code, 4.2/4.3/4.4 regression] Patch for PR38615

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

On Wed, 21 Jan 2009, Richard Guenther wrote:

> If it has automatic storage duration, do C or C++ require that automatic
> variables have distinct locations?  Thus, is this bug invalid?  (Of course
> both automatic variables have overlapping lifetime)
> 
> So, can a compiler assign the same memory to i and j in
> 
>   int i, j;
>   i = 0;
>   j = 0;
>   return i + j;

i and j are distinct objects so must have addresses that do not compare 
equal (if the addresses are taken so pointers to both objects are compared 
at a time when both pointers are valid).  This applies to any two 
automatic variables with overlapping lifetimes (but once an object's 
lifetime has ended, any further use of a pointer to it is undefined 
behavior).

-- 
Joseph S. Myers
joseph@codesourcery.com