In article <20061030074656.GJ1205@snowdrop.l8s.co.uk>,
David Laight  <david@l8s.co.uk> wrote:
>On Mon, Oct 30, 2006 at 07:03:34AM +0000, Havard Eidnes wrote:
>> 
>> Module Name:	src
>> Committed By:	he
>> Date:		Mon Oct 30 07:03:34 UTC 2006
>> 
>> Modified Files:
>> 	src/usr.sbin/installboot: ffs.c
>> 
>> Log Message:
>> In order to avoid warnings (which is converted to error with -Werror)
>> about empty bodies in an if-statement, we need to make add some proprocessor
>> conditionals around these if statements.  FFS byte-swapping is sometimes
>> compiled out of install-media versions of this program.
>
>Having to do that is just plain stupid....
>
>I've also deliberatly used:
>
>#define x(y)   if (y); else {...}
>
>To avoid having to wrap the expansion inside do ... while (0);

How is one supposed to use this macro? As 

	a = 3;
	x(y)
	b = 4;
or
	a = 3;
	x(y);
	b = 4;

And then doesn't this completely screw up:

	if (z)
		x(y);
	else
		a = 4;


This is why such macros are not the best thing :-)

christos