From mboxrd@z Thu Jan  1 00:00:00 1970
From: lars@metafoo.de (Lars-Peter Clausen)
Date: Mon, 20 May 2013 21:13:34 +0200
Subject: [Cocci] isomorphism with unlikely
In-Reply-To: <alpine.DEB.2.02.1305202051210.2036@localhost6.localdomain6>
References: <20130520173406.GB5890@katana> <519A61A8.7010402@metafoo.de>
 <20130520182415.GA6975@katana> <519A6ABC.1090004@metafoo.de>
 <alpine.DEB.2.02.1305202051210.2036@localhost6.localdomain6>
Message-ID: <519A75DE.1040604@metafoo.de>
To: cocci@systeme.lip6.fr
List-Id: cocci@systeme.lip6.fr

On 05/20/2013 08:51 PM, Julia Lawall wrote:
> On Mon, 20 May 2013, Lars-Peter Clausen wrote:
> 
>> On 05/20/2013 08:24 PM, Wolfram Sang wrote:
>>>
>>>> There is already an isomorphism for unlikely. But it is in one direction
>>>> only, so 'unlikely(E)' in your cocci script will also match 'E', but 'E'
>>>> wont match 'unlikely(E)'.
>>>
>>> Okay, but I would then still need 'unlikely(!r)' and 'unlikely(r ==
>>> NULL)' because the !r isomorphisms won't apply. I'd like to have both :)
>>
>> No, just unlikley(r == NULL) also matches !r (and unlikely(!r)). This should
>> also work for unlikely(!r) matching unlikely(r == NULL) but for some reason
>> it doesn't. I just did a quick test and it looks as if even 'if(!r) ..."
>> doesn't match 'if(r == NULL) ...' either.
> 
> It should work if r has pointer type.  Otherwise, if r is not a pointer, 
> then !r should become r == 0.

But for some reason it does not. With --verbose-match I can see that it
generates the correct isomorphisms (both for the case that r is a pointer or
that r is an integer), but for some reason they don't seem to match.

The testcase is simple:

cocci file:

@@
expression *r;
statement S;
@@
*if(!r) S

c file:

int foo(struct resource *r)
{
	if (r == NULL)
		return 0;
	return 1;
}

- Lars