Re: [jamboost] Patch for jam bug on Cray

From: Matthias Troyer (troyer_at_[hidden])
Date: 2003-01-23 17:40:31

On Wednesday, January 22, 2003, at 07:56 PM, Matthias Troyer wrote:

> Dear Boost Jamers,
>
> Our local Cray adminstrators (Bruno Loepfe from ETH and Olivier Byrde
> from Cray) found a bug in the boost jam sources. it is in the file
> hash.c:
>
>
> keyval = keyval * 2147059363 + *b++;

Besides the bug fix I posted before, our Cray system administrator 
warned me that there are (were) machines which trap integer overflow, 
and where above code would not work. He proposed to use a hash function 
employing exclusive or operations instead. In contrast to fixing the 
bug for which I sent the patch, this is s however definitively not an 
urgent problem. It should be kept in mind however in case that we ever 
encounter a modern machine trapping integer overflows.

Matthias