[Cocci] Strange behavior with replacing multiple typedefs

Julia Lawall julia.lawall at lip6.fr
Sun Sep 16 17:07:20 CEST 2018



On Sun, 16 Sep 2018, Moustafa Mahmoud wrote:

> Hello all,
> I am facing this problem with typedefs, what I am trying to achieve is convering multiple typedefs into single ones. 
>
>
> typedef int x,y;
> into :
>
> typedef  int x;
> typedef int y;
>
>
> when I try to replace them inside functions, everything works as expected\
>
> My Rule :
> @rule1@
> identifier fn;
> type t;
> metavariable mm;
> @@
>
> ++ typedef t mm;
> fn(...){
> <+...
> - typedef t mm;
> ...+>
> }
>
> The C Code 
>
> typedef int;
> typedef int mr,e4;
>
> int main()
> {
>     typedef int sss, ssd;
> }
>
> The Diff :
> diff =
> --- typedef.c
> +++ /tmp/cocci-output-91048-e42770-typedef.c
> @@ -3,7 +3,8 @@
>  typedef int;
>  typedef int mr,e4;
>
> +typedef int ssd;
> +typedef int sss;
>  int main()
>  {
> -    typedef int sss, ssd;
>  }
> \ No newline at end of file
>
>
> However if I try to generalize it 
>
> @rule1@
> type t;
> metavariable mm;
> @@
>
> ++ typedef t mm;
> - typedef t mm;
>
>
>
> The C Code:
>
> typedef int;
> typedef int mr,e4;
>
> int main()
> {
>     typedef int sss, ssd;
> }
>
> What I get is this :
>
>  typedef int;
> -typedef int mr,e4;
> +typedef int e4;
> +typedef int mr;
> +typedef int;
>
>  int main()
>  {
> -    typedef int sss, ssd;
> +    typedef int ssd;
> +    typedef int sss;
> +    typedef int;
>  }
> \ No newline at end of file
>
>
> You can notice the extra  "+  typedef int;" , why are those produced ? is there a way to achieve what  want without them ?

Wow, I'm thrilled that it worked at all :)  I knew that that would work
for eg int x,y,z;, but I didn't realize that it would work for typedefs
too.

I have the impression that it is pulling out the individual typedefs like
you asked, but then it is not actually deleting the typedef t ; part.
That is, it is not adding typedef int; it is just not removing the
original typedef after pulling out eg mr and e4.  I will see if I can fix
it.  In the short term , I don't see any workaround, unfortunately.

julia


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