Less commas

[Patrick Kreft]

On Sun, 02 Jan 2011 21:04:07 +0100, Walter Bright  
<newshound2 at digitalmars.com> wrote:

> bearophile wrote:
>> A common bug in Linux kernel:
>>  if(!state->card->
>>   ac97_status&CENTER_LFE_ON)
>>      val&=~DSP_BIND_CENTER_LFE;
>>  The fix is to replace (!E & C) with (!(E & C)).
>>  Currently D acts like C:
>>  void main() {
>>     uint x, y;
>>     if (!x & y) {}
>> }
>>  - 96 instances of this bug in Linux from 2.6.13 (August 2005) to  
>> v2.6.28 (December 2008).
>> - 58 instances of this bug in 2.6.20 (February 2007)
>> - 2 in Linux-next (October 10, 2009)
>>  They have faced and reduced the number of such bugs using Coccinelle,  
>> see pages 8-9 here:
>> http://coccinelle.lip6.fr/papers/fosdem10.pdf
>
> This is great stuff, bearophile. Thanks for finding that. Please add  
> this as an enhancement request to bugzilla (disallowing (!x&y)  
> expressions).


The false-positive are shown in the presentation ... okey it's was irony,  
or not? Better is that:


   let is = func[T](state: ref const T, of: val T -> bool):
     return !(state & of)


   if(is(state=obj.flag, of=MAYBE_THIS_STATE)):
     ...