Subj : Re: double-checked locking in C
To   : comp.programming.threads
From : David Hopwood
Date : Fri Jul 08 2005 08:34 pm

Alexander Terekhov wrote:
> Laurent Deniau wrote:
> [...]
> 
>>observable behavior 
> 
> Volatiles objects with standard storage duration don't have any 
> "observable behavior". 
> 
> Debuggers (and things like that... beyond the scope of the standard) 
> aside for a moment, how are you going to establish nonconformance of 
> transformation 
> 
>   int main() { 
>     volatile int foo = 1; 
>     return --foo; 
>   } 
> 
> to 
> 
>   int main() { 
>   } 
> 
> <?>

Indeed. The whole idea of 'volatile' in C is incoherent; the language
definition specifies by fiat that accesses to volatile objects are
always observable side effects, when in many cases they manifestly
are not.

-- 
David Hopwood <david.nospam.hopwood@blueyonder.co.uk>

.