Re: [cocci] match arbitrary argument position

[Jakob Koschel <jkl820.git@gmail.com>]

Hey,

> On 16. Aug 2022, at 19:55, Markus Elfring <Markus.Elfring@web.de> wrote:
> 
>> looking at the following code snippet:
>> 
>> test.c:
> …
>>      func3(argc, argv);
>> 
>>      func3(argv);
> 
> 
> Would you like to handle function overloading here?

I'm not exactly sure I understand what you mean here.

Finally I would like to archive something like this:

void func(void) {

    int x = 0;
    int y = 0;

    func1(x, 0);
    func2(0, y);
}

void func1(int arg1, int arg2) {
    interesting_func(arg1);
}

void func2(int arg1, int arg2) {
    interesting_func(arg2);
}

In the end I want to, for example, turn it into:

void func(void) {

    int x = 0;
    // 'x' was used as first argument to interesting_func
    int y = 0;
    // 'y' was used as first argument to interesting_func

    func1(x, 0);
    func2(0, y);
}

void func1(int arg1, int arg2) {
    interesting_func(arg1);
}

void func2(int arg1, int arg2) {
    interesting_func(arg2);
}

Basically I want to flag create the matching from 'x'/'y' to the argument to interesting_func.

I was imagining if I could match the parameter list of any function calling 'interesting_func'
then I can also create a matching from x to that function call and do the rest of the correlation
in python somehow.

However I'm still failing to detect if any argument (arg1 or arg2 in this case) is used as
any argument in 'interesting_func'.

I hope this makes more sense?

> 
> 
> 
>> what doesn't work (matching on the expression list from the parameter list):
>> 
>>   @main4@
>>   expression list Es;
>>   @@
>> 
>>   int func1(Ps@Es) {
>>   ...
>>   }
> 
> 
> Which type would belong to the metavariable “Ps”?

Ps should be an arbitrary length parameter list with arbitrary types.

> 
> 
> 
>> I also tried this:
>> 
>>   @main4@
>>   parameter P;
>>   expression E;
>>   @@
>> 
>>   int func1(..., P@E, ...) {
>>   ...
>>   }
> 
> 
> Does such SmPL code represent a contradiction?
> 
> 
> Can any other descriptions indicate your data processing imaginations better?

hopefully the example above makes it a bit more clear.

> 
> 
>>   @main5@
>>   expression main4.E;
>>   identifier func;
>>   @@
>> 
>>     func(..., E, ...);
>>   + // add comment
>> 
>> 
>> But it throws: 'rule starting on line 41 contains unattached metavariables: main4.E'.
> 
> Which software version did you try out here?

I'm guessing this will give you all the information you want:
spatch version 1.1.1-00124-ge93f5513 compiled with OCaml version 4.13.1


> 
> I am curious how corresponding considerations will evolve further.
> 
> 
> Regards,
> Markus
> 

Thanks!
Jakob