[Drawkit] compiling b6

[Graham Cox]

On 28/08/2009, at 3:08 AM, James Maxwell wrote:

> Just curious. I'm finally getting around to building beta 6, and I'm  
> getting all sorts of warning about "_a" shadowing a previous local,  
> when I try to build beta 6.
> Is this anything to worry about? Does it point to some other problem  
> in my build directory, perhaps?


Hi James,

This is a nuisance - but no more than that. It's caused by the  
implementation of the MIN and MAX macros. It's not unusual to nest  
these to clip a value between an upper and a lower limit:


val = MAX(MIN(val, upper), lower)

unfortunately when you do this you end up with two local variables  
called _a in the expansion of the macros (both MIN and MAX chose '-a'  
whereas they could easily have used something different). It doesn't  
stop them working properly when nested but it throws up this warning.  
I should probably get around to filing a bug on this with Apple.

If it bugs you there is DK's own LIMIT macro which clips a value  
between two limits without this warning. I've been gradually replacing  
nested MIN/MAX calls with this.

--Graham