[sane-devel] C undefined operations in sane-backends-1.0.7-beta1

[Tim Waugh]

On Fri, Jan 25, 2002 at 12:27:03PM +0100, Jaeger, Gerhard wrote:

> Hi there, 
> 
> let's have a look at the warnings from the Plustek backend.
> The lines that produce the problem include the following statement:
> 
> _SWAP(x,y)	(x)^=(y)^=(x)^=(y)
> 
> So what? Where's the problem here?

I think the problem is that there are two assignments to x with no
intervening sequence point.  Although the expression (x)^=(y) is
_evaluated_ first, it doesn't mean that the resulting value is then
assigned to x before the result of the expression (y)^=(x)^=(y) is;
the compiler is free to do it the other way around.

Tim.
*/
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 232 bytes
Desc: not available
URL: <http://alioth-lists.debian.net/pipermail/sane-devel/attachments/20020125/d8ae4326/attachment.sig>